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Gérard, Odile, Craig Carthel, and Stefano Coraluppi. "Détection et classification automatique de signaux acoustiques de baleines à bec." Traitement du signal 33, no. 1 (October 28, 2016): 73–94. http://dx.doi.org/10.3166/ts.33.73-94.
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Kun, E., Z. Keresztes, and L. Á. Gergely. "Slowly rotating Bose–Einstein condensate compared with the rotation curves of 12 dwarf galaxies." Astronomy & Astrophysics 633 (January 2020): A75. http://dx.doi.org/10.1051/0004-6361/201936504.
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Context. The high plateaus of the rotation curves of spiral galaxies suggest either that there is a dark component or that the Newtonian gravity requires modifications on galactic scales to explain the observations. We assemble a database of 12 dwarf galaxies, for which optical (R-band) and near-infrared (3.6 μm) surface brightness density together with spectroscopic rotation curve data are available, in order to test the slowly rotating Bose–Einstein condensate (BEC) dark matter model. Aims. We aim to establish the angular velocity range compatible with observations, bounded from above by the requirement of finite-size halos, to check the model fits with the dataset, and the universality of the BEC halo parameter ℛ. Methods. We constructed the spatial luminosity density of the stellar component of the dwarf galaxies based on their 3.6 μm and R-band surface brightness profiles, assuming an axisymmetric baryonic mass distribution with arbitrary axis ratio. We built up the gaseous component of the mass by employing an inside-truncated disk model. We fitted a baryonic plus dark matter combined model, parametrized by the M/L ratios of the baryonic components and parameters of the slowly rotating BEC (the central density ρc, size of the BEC halo ℛ in the static limit, angular velocity ω) to the rotation curve data. Results. The 3.6 μm surface brightness of six galaxies indicates the presence of a bulge and a disk component. The shape of the 3.6 μm and R-band spatial mass density profiles being similar is consistent with the stellar mass of the galaxies emerging wavelength-independent. The slowly rotating BEC model fits the rotation curve of 11 galaxies out of 12 within the 1σ significance level, with the average of ℛ as 7.51 kpc and standard deviation of 2.96 kpc. This represents an improvement over the static BEC model fits, also discussed. For the 11 best-fitting galaxies the angular velocities allowing for a finite-size slowly rotating BEC halo are less then 2.2 × 10−16 s−1.For a scattering length of the BEC particle of a ≈ 106 fm, as allowed by terrestrial laboratory experiments, the mass of the BEC particle is slightly better constrained than in the static case as m ∈ [1.26 × 10−17 ÷ 3.08 × 10−17] (eV c−2).
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Morawska, Alina, Michelle Adamson, and Joanne Ferriol Especkerman. "Mealtime Observations and Parent-Report: Correspondence Across Measurement and Implications for Intervention." Behaviour Change 32, no. 3 (July 27, 2015): 175–89. http://dx.doi.org/10.1017/bec.2015.9.
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This study explored the relationship between self-reported and observed mealtime behaviour and examined concurrent predictors of observed child and parent mealtime behaviour. The sample consisted of 67 parents of 1.5- to 6-year-old children experiencing difficulties with their child's mealtime, and 33 parents who were not concerned with their child's mealtime behaviour. Parent-reported and observed mealtime data, and parent-reported mealtime cognitions were collected. Regression analyses indicated that consistent with hypotheses, observed and parent-reported mealtime behaviour were related. Observed child behaviour was predicted by self-reported parenting behaviour and observed positive parent behaviour, as well as parental cognitions. Observed parent behaviour was predicted only by self-reported parenting mealtime behaviour.
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Davis, Benjamin, Xuguang Wang, and Xu Lu. "A Comparison of HWRF Six-Hourly 4DEnVar and Hourly 3DEnVar Assimilation of Inner Core Tail Dopper Radar Observations for the Prediction of Hurricane Edouard (2014)." Atmosphere 12, no. 8 (July 22, 2021): 942. http://dx.doi.org/10.3390/atmos12080942.
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Six-hourly three-dimensional ensemble variational (3DEnVar) (6H-3DEnVar) data assimilation (DA) assumes constant background error covariance (BEC) during a six-hour DA window and is, therefore, unable to account for temporal evolution of the BEC. This study evaluates the one-hourly 3DEnVar (1H-3DEnVar) and six-hourly 4DEnVar (6H-4DEnVar) DA methods for the analyses and forecasts of hurricanes with rapidly evolving BEC. Both methods account for evolving BEC in a hybrid EnVar DA system. In order to compare these methods, experiments are conducted by assimilating inner core Tail Doppler Radar (TDR) wind for Hurricane Edouard (2014) and by running the Hurricane Weather Research and Forecasting (HWRF) model. In most metrics, 1H-3DEnVar and 6H-4DEnVar analyses and forecasts verify better than 6H-3DEnVar. 6H-4DEnVar produces better thermodynamic analyses than 1H-3DEnVar. Radar reflectivity shows that 1H-3DEnVar produces better structure forecasts. For the first 24–48 h of the intensity forecast, 6H-4DEnVar forecast performs better than 1H-3DEnVar verified against the best track. Degraded 1H-3DEnVar forecasts are found to be associated with background storm center location error as a result of underdispersive ensemble storm center spread. Removing location error in the background improves intensity forecasts of 1H-3DEnVar.
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Kim, Sung-Min, and Hyun Mee Kim. "Forecast Sensitivity Observation Impact in the 4DVAR and Hybrid-4DVAR Data Assimilation Systems." Journal of Atmospheric and Oceanic Technology 36, no. 8 (August 2019): 1563–75. http://dx.doi.org/10.1175/jtech-d-18-0240.1.
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AbstractIn this study, the observation impacts on 24-h forecast error reduction (FER), based on the adjoint method in the four-dimensional variational (4DVAR) data assimilation (DA) and hybrid-4DVAR DA systems coupled with the Unified Model, were evaluated from 0000 UTC 5 August to 1800 UTC 26 August 2014. The nonlinear FER in hybrid-4DVAR was 12.2% greater than that in 4DVAR due to the use of flow-dependent background error covariance (BEC), which was a weighted combination of the static BEC and the ensemble BEC based on ensemble forecasts. In hybrid-4DVAR, the observation impacts (i.e., the approximated nonlinear FER) for most observation types increase compared to those in 4DVAR. The increased observation impact from using hybrid-4DVAR instead of 4DVAR changes depending on the analysis time and regions. To calculate the ensemble BEC in hybrid-4DVAR, analyses at 0600 and 1800 UTC (0000 and 1200 UTC) used 3-h (9-h) ensemble forecasts. Greater observation impact was obtained when 3-h ensemble forecasts were used for the ensemble BEC at 0600 and 1800 UTC, than with 9-h ensemble forecasts at 0000 and 1200 UTC. Different from other observations, the atmospheric motion vectors (AMVs) deduced from geostationary satellite are more frequently observed in the same area. When the ensemble forecasts with longer integration times were used for the ensemble BEC in hybrid-4DVAR, the observation impact of the AMVs decreased the most in East Asia. This implies that the observation impact of AMVs in East Asia shows the highest sensitivity to the integration time of the ensemble members used for deducing the flow-dependent BEC in hybrid-4DVAR.
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Barthelemy, Dominique. "Une crise de l’écrit ? Observations sur des actes de Saint-Aubin d’Angers (XIe siècle)." Bibliothèque de l'école des chartes 155, no. 1 (1997): 95–117. http://dx.doi.org/10.3406/bec.1997.450860.
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Castellanos, Elías, Celia Escamilla-Rivera, and Jorge Mastache. "Is a Bose–Einstein condensate a good candidate for dark matter? A test with galaxy rotation curves." International Journal of Modern Physics D 29, no. 09 (July 2020): 2050063. http://dx.doi.org/10.1142/s0218271820500637.
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We analyze the rotation curves that correspond to a Bose–Einstein Condensate (BEC)-type halo surrounding a Schwarzschild-type black hole to confront predictions of the model upon observations of galaxy rotation curves. We model the halo as a BEC in terms of a massive scalar field that satisfies a Klein–Gordon equation with a self-interaction term. We also assume that the bosonic cloud is not self-gravitating. To model the halo, we apply a simple form of the Thomas–Fermi approximation that allows us to extract relevant results with a simple and concise procedure. Using galaxy data from a subsample of SPARC data base, we find the best fits of the BEC model by using the Thomas–Fermi approximation and perform a Bayesian statistics analysis to compare the obtained BEC’s scenarios with the Navarro–Frenk–White (NFW) model as pivot model. We find that in the centre of galaxies, we must have a supermassive compact central object, i.e. supermassive black hole, in the range of [Formula: see text] which condensate a boson cloud with average particle mass [Formula: see text] eV and a self-interaction coupling constant [Formula: see text], i.e. the system behaves as a weakly interacting BEC. We compare the BEC model with NFW concluding that in general the BEC model using the Thomas–Fermi approximation is strong enough compared with the NFW fittings. Moreover, we show that BECs still well-fit the galaxy rotation curves and, more importantly, could lead to an understanding of the dark matter nature from first principles.
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Kay, Junkyung, and Xuguang Wang. "A Multiresolution Ensemble Hybrid 4DEnVar for Global Numerical Prediction." Monthly Weather Review 148, no. 2 (February 1, 2020): 825–47. http://dx.doi.org/10.1175/mwr-d-19-0002.1.
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Abstract A multiresolution ensemble (MR-ENS) method is developed to resolve a wider range of scales of the background error covariance (BEC) in the hybrid four-dimensional ensemble–variational (4DEnVar) while saving computational costs. MR-ENS is implemented in the NCEP Global Forecast System (GFS) gridpoint statistical interpolation (GSI) hybrid 4DEnVar. MR-ENS generates analysis increment by incorporating high-resolution static BEC and flow-dependent ensemble BECs from both high and low resolutions. MR-ENS is compared with three 4DEnVar update approaches: 1) the single-resolution (SR)-Low approach where the analysis increments are generated from the ensemble BEC and the static BEC at the same low resolution; 2) the dual-resolution (DR) approach where the analysis increment is generated using the high-resolution static BEC and low-resolution ensemble BEC; and 3) the SR-High approach, which is the same as 1) except that all covariances are at high-resolution. Experiments show that MR-ENS improves global and tropical cyclone track forecasts compared to SR-Low and DR. Inclusion of the high-resolution ensemble leads to increased background ensemble spread, better fitting of the background to observations, increased effective ranks, more accurate ensemble error correlation, and increased power of analysis increment at small scales. The majority of the improvement of MR-ENS relative to SR-Low is due to the partial use of high-resolution background ensemble. Compared to SR-High, MR-ENS decreases the overall cost by about 40% and shows comparable global and tropical cyclone track forecast performances. Diagnostics show that particularly in the tropics, MR-ENS improves the analysis increment over a wide range of scales and increases the effective rank of the ensemble BEC to the degree comparable to SR-High.
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Horne, David James de Lancy. "The Emergence and Development of Cognitive Behaviour Therapy in Australia: Observations from an Early Player." Behaviour Change 36, no. 4 (November 29, 2019): 192–99. http://dx.doi.org/10.1017/bec.2019.18.
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Xie, Jiping, Roshin P. Raj, Laurent Bertino, Annette Samuelsen, and Tsuyoshi Wakamatsu. "Evaluation of Arctic Ocean surface salinities from the Soil Moisture and Ocean Salinity (SMOS) mission against a regional reanalysis and in situ data." Ocean Science 15, no. 5 (September 6, 2019): 1191–206. http://dx.doi.org/10.5194/os-15-1191-2019.
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Abstract. Recently two gridded sea surface salinity (SSS) products that cover the Arctic Ocean have been derived from the European Space Agency (ESA)'s Soil Moisture and Ocean Salinity (SMOS) mission: one developed by the Barcelona Expert Centre (BEC) and the other developed by the Ocean Salinity Expertise Center of the Centre Aval de Traitement des Données SMOS at IFREMER (The French Research Institute for Exploitation of the Sea) (CEC). The uncertainties of these two SSS products are quantified during the period of 2011–2013 against other SSS products: one data assimilative regional reanalysis; one data-driven reprocessing in the framework of the Copernicus Marine Environment Monitoring Services (CMEMS); two climatologies – the 2013 World Ocean Atlas (WOA) and the Polar science center Hydrographic Climatology (PHC); and in situ datasets, both assimilated and independent. The CMEMS reanalysis comes from the TOPAZ4 system, which assimilates a large set of ocean and sea-ice observations using an ensemble Kalman filter (EnKF). Another CMEMS product is the Multi-OBservations reprocessing (MOB), a multivariate objective analysis combining in situ data with satellite SSS. The monthly root mean squared deviations (RMSD) of both SMOS products, compared to the TOPAZ4 reanalysis, reach 1.5 psu in the Arctic summer, while in the winter months the BEC SSS is closer to TOPAZ4 with a deviation of 0.5 psu. The comparison of CEC satellite SSS against in situ data shows Atlantic Water that is too fresh in the Barents Sea, the Nordic Seas, and in the northern North Atlantic Ocean, consistent with the abnormally fresh deviations from TOPAZ4. When compared to independent in situ data in the Beaufort Sea, the BEC product shows the smallest bias (< 0.1 psu) in summer and the smallest RMSD (1.8 psu). The results also show that all six SSS products share a common challenge: representing freshwater masses (< 24 psu) in the central Arctic. Along the Norwegian coast and at the southwestern coast of Greenland, the BEC SSS shows smaller errors than TOPAZ4 and indicates the potential value of assimilating the satellite-derived salinity in this system.
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Zinner, N. T. "Vortex Structures in a Rotating BEC Dark Matter Component." Physics Research International 2011 (October 13, 2011): 1–12. http://dx.doi.org/10.1155/2011/734543.
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We study the effects of a dark matter component that consists of bosonic particles with ultralight masses in the condensed state. We compare previous studies for both noninteracting condensates and with repulsive two-body terms and show consistency between the proposals. Furthermore, we explore the effects of rotation on a superfluid dark matter condensate, assuming that a vortex lattice is formed as seen in ultracold atomic gas experiments. The influence of such a lattice in virialization of gravitationally bound structures and on galactic rotation velocity curves is explored. With fine-tuning of the bosonic particle mass and the two-body repulsive interaction strength, we find that one can have substructure on rotation curves that resembles some observations in spiral galaxies. This occurs when the dark matter halo has an array of hollow cylinders. This can cause oscillatory behavior in the galactic rotation curves in similar fashion to the well-known effect of the spiral arms. We also consider how future experiments and numerical simulations with ultracold atomic gases could tell us more about such exotic dark matter proposals.
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Morikawa, Masahiro. "Supermassive Black Holes from Bose-Einstein Condensed Dark Matter—Or Black and Dark Separation by Angular Momentum." Universe 7, no. 8 (July 26, 2021): 265. http://dx.doi.org/10.3390/universe7080265.
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Many supermassive black holes (SMBH) of mass 106∼9M⊙ are observed at the center of each galaxy even in the high redshift (z≈7) Universe. To explain the early formation and the common existence of SMBH, we previously proposed the SMBH formation scenario by the gravitational collapse of the coherent dark matter (DM) composed from the Bose-Einstein Condensed (BEC) objects. A difficult problem in this scenario is the inevitable angular momentum which prevents the collapse of BEC. To overcome this difficulty, in this paper, we consider the very early Universe when the BEC-DM acquires its proper angular momentum by the tidal torque mechanism. The balance of the density evolution and the acquisition of the angular momentum determines the mass of the SMBH as well as the mass ratio of BH and the surrounding dark halo (DH). This ratio is calculated as MBH/MDH≈10−3∼−5(Mtot/1012M⊙)−1/2 assuming simple density profiles of the initial DM cloud. This result turns out to be consistent with the observations at z≈0 and z≈6, although the data scatter is large. Thus, the angular momentum determines the separation of black and dark, i.e., SMBH and DH, in the original DM cloud.
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Bec-Borsenberger, A. "Solar System Objects in the HIPPARCOS Programme." Highlights of Astronomy 9 (1992): 398. http://dx.doi.org/10.1017/s153929960000928x.
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AbstractForty eight minor planets and two planetary satellites have been retained in the Hipparcos programme. The observations of minor planets will be used to try to determine the dynamical equinox and the rotation of the Hipparcos reference system (S. Söderhjelm and Lindegren, 1982); they can be also used to determine some physical properties of minor planets. As for the observations of planetary satellites, they will allow to obtain accurate ephemendes of these objects and to improve those of the primary planets. The inclusion of minor planets and satellites in the observing programme raises very specific problems: owing to their motion, positions of these objects are given in the Input Catalogue using ephemerides; preparatory astrometric work needed for improving these ephemerides (ground-based observations and improvement of orbital elements) has been described in Bec-Borsenberger (1989, 1991a). To be sure that the ephemerides are sufficient to get the 1 arcsecond predictability needed for Hipparcos, a reduced programme of ground-based observations will last all along the Hipparcos campaign (with the automatic meridian circles of Bordeaux and La Palma observatories). Presently, an annual update is adequate in order to ensure this precision. The improved orbital elements and predicted ephemerides for years 1991 and 1992 are published (Bec-Borsenberger, 1990, 1991b): the residuals obtained from the last set of improved elements with the meridian observations made for the Hipparcos programme givermsin right ascension and declination between 0.19 and 0.38 arcsecond for all Hipparcos minor planets. Since the launch of Hipparcos, the two satellites have been observed and about a third of the minor planets of the programme have been found; the previsions allow to hope to observe this year about ten more minor planets.
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Zang, Z., Z. Hao, Y. Li, X. Pan, W. You, Z. Li, and D. Chen. "Background error covariance with balance constraints for aerosol species and applications in data assimilation." Geoscientific Model Development Discussions 8, no. 11 (November 16, 2015): 10053–88. http://dx.doi.org/10.5194/gmdd-8-10053-2015.
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Abstract. Balance constraints are important for a background error covariance (BEC) in data assimilation to spread information between different variables and produce balance analysis fields. Using statistical regression, we develop the balance constraint for the BEC of aerosol variables and apply it to a data assimilation and forecasting system for the WRF/Chem model. One-month products from the WRF/Chem model are employed for BEC statistics with the NMC method. The cross-correlations among the original variables are generally high. The highest correlation between elemental carbon and organic carbon without balance constraints is approximately 0.9. However, the correlations for the unbalanced variables are less than 0.2 with the balance constraints. Data assimilation and forecasting experiments for evaluating the impact of balance constraints are performed with the observations of the surface PM2.5 concentrations and speciated concentrations along an aircraft flight track. The speciated increments of the experiment with balance constraints are more coincident than the speciated increments of the experiment without balance constraints, for the observation information can spread across variables by balance constraints in the former experiment. The forecast results of the experiment with balance constraints show significant and durable improvements from the 3rd hour to the 18th hour compared with the forecast results of the experiment without the balance constraints. However, the forecasts of these two experiments are similar during the first 3 h. The results suggest that the balance constraint is significantly positive for the aerosol assimilation and forecasting.
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Banos, Ivette H., Will D. Mayfield, Guoqing Ge, Luiz F. Sapucci, Jacob R. Carley, and Louisa Nance. "Assessment of the data assimilation framework for the Rapid Refresh Forecast System v0.1 and impacts on forecasts of a convective storm case study." Geoscientific Model Development 15, no. 17 (September 12, 2022): 6891–917. http://dx.doi.org/10.5194/gmd-15-6891-2022.
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Abstract. The Rapid Refresh Forecast System (RRFS) is currently under development and aims to replace the National Centers for Environmental Prediction (NCEP) operational suite of regional- and convective-scale modeling systems in the next upgrade. In order to achieve skillful forecasts comparable to the current operational suite, each component of the RRFS needs to be configured through exhaustive testing and evaluation. The current data assimilation component uses the hybrid three-dimensional ensemble–variational data assimilation (3DEnVar) algorithm in the Gridpoint Statistical Interpolation (GSI) system. In this study, various data assimilation algorithms and configurations in GSI are assessed for their impacts on RRFS analyses and forecasts of a squall line over Oklahoma on 4 May 2020. A domain of 3 km horizontal grid spacing is configured, and hourly update cycles are performed using initial and lateral boundary conditions from the 3 km grid High-Resolution Rapid Refresh (HRRR). Results show that a baseline RRFS run is able to represent the observed convection, although with stronger cells and large location errors. With data assimilation, these errors are reduced, especially in the 4 and 6 h forecasts using 75 % of the ensemble background error covariance (BEC) and 25 % of the static BEC with the supersaturation removal function activated in GSI. Decreasing the vertical ensemble localization radius from 3 layers to 1 layer in the first 10 layers of the hybrid analysis results in overall less skillful forecasts. Convection is greatly improved when using planetary boundary layer pseudo-observations, especially at 4 h forecast, and the bias of the 2 h forecast of temperature is reduced below 800 hPa. Lighter hourly accumulated precipitation is predicted better when using 100 % ensemble BEC in the first 4 h forecast, but heavier hourly accumulated precipitation is better predicted with 75 % ensemble BEC. Our results provide insight into the current capabilities of the RRFS data assimilation system and identify configurations that should be considered as candidates for the first version of RRFS.
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Mlodinow, Steven G., and Robert L. Norton. "First record of Red-billed Tropicbird (<em>Phaethon aethereus</em>) for Aruba." Journal of Caribbean Ornithology 30, no. 2 (May 13, 2018): 143–44. http://dx.doi.org/10.55431/jco.2017.30.143-144.
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Abstract: Robert L. Norton encountered a Red-billed Tropicbird (Phaethon aethereus) approximately 60 km NNW of Aruba, providing Aruba’s first record of this species. Given the pelagic distribution of this species during the non-breeding season, and nine antecedent records from Bonaire and Curaçao, additional records seem likely for Aruba, especially given an increase in reports of seabirds from cruise ships off Aruba.
Keywords: Aruba, first record, non-breeding range, Phaethon aethereus, Red-billed Tropicbird
Resumen: Primer registro de Phaethon aethereus para Aruba—Robert L. Norton encontró un individuo de Phaethon aethereus aproximadamente a 60 km NNO de Aruba, lo que constituye el primer registro de esta especie para la isla. Dada la distribución pelágica de esta especie durante la época no reproductiva y los nueve registros anteriores en Bonaire y Curazao, es probable que Aruba tenga registros adicionales, especialmente dado el aumento de avistamientos de aves marinas desde cruceros en la isla.
Palabras clave: Aruba, Phaethon aethereus, primer registro, rango no reproductivo
Résumé: Première mention du Phaéton à bec rouge (Phaethon aethereus) à Aruba—Robert L. Norton a observé un Phaéton à bec rouge (Phaethon aethereus) environ 60 km au nord-nord-ouest d’Aruba, ce qui constitue la première mention de cette espèce pour Aruba. Compte tenu de la répartition pélagique de l’espèce en dehors de la saison de reproduction et des neuf observations antérieures à Bonaire et Curaçao, des mentions supplémentaires semblent probables pour Aruba, en particulier en raison de l’augmentation des signalements d’oiseaux marins depuis des navires de croisière au large d’Aruba.
Mots clés: Aruba, Phaethon aethereus, Phaéton à bec rouge, première mention, zone fréquentée en dehors de la période de reproduction
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RINDLER-DALLER, TANJA, and PAUL R. SHAPIRO. "COMPLEX SCALAR FIELD DARK MATTER ON GALACTIC SCALES." Modern Physics Letters A 29, no. 02 (January 20, 2014): 1430002. http://dx.doi.org/10.1142/s021773231430002x.
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The nature of the cosmological dark matter (DM) remains elusive. Recent studies have advocated the possibility that DM could be composed of ultra-light, self-interacting bosons, forming a Bose–Einstein condensate (BEC) in the very early Universe. We consider models which are charged under a global U(1)-symmetry such that the DM number is conserved. It can then be described as a classical complex scalar field which evolves in an expanding Universe. We present a brief review on the bounds on the model parameters from cosmological and galactic observations, along with the properties of galactic halos which result from such a DM candidate.
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Li, Xichen, Jiang Zhu, Yiguo Xiao, and Ruiwen Wang. "A Model-Based Observation-Thinning Scheme for the Assimilation of High-Resolution SST in the Shelf and Coastal Seas around China." Journal of Atmospheric and Oceanic Technology 27, no. 6 (June 1, 2010): 1044–58. http://dx.doi.org/10.1175/2010jtecho709.1.
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Abstract The use of high-density remote sensing buoys and ship-based observations play an increasingly crucial role in the operational assimilation and forecast of oceans. With the recent release of several high-resolution observation datasets, such as the Global Ocean Data Assimilation Experiment (GODAE) high-resolution SST (GHRSST) datasets, the development of observation-thinning schemes becomes important in the process of data assimilation because the huge quantity and dense spatial–temporal distributions of these datasets might make it expensive to assimilate the full dataset into ocean models or even decay the assimilation result. In this paper, an objective model simulation ensemble-based observation-thinning scheme is proposed and applied to a Chinese shelf–coastal seas eddy-resolving model. A successful thinning scheme should select a subset of observations yielding a small analysis error variance (AEV) while keeping the number of observations to as few as possible. In this study, the background error covariance (BEC) is estimated using the historical ensemble and then the subset of observations to minimize the AEV is selected, which is estimated from the Kalman theory. The authors used this method in the GHRSST product to cover the shelf and coastal seas around China and then verified the result with an estimation function and assimilation–forecast systems.
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Ardila, Luis A. Peña. "Ultra-Dilute Gas of Polarons in a Bose–Einstein Condensate." Atoms 10, no. 1 (March 2, 2022): 29. http://dx.doi.org/10.3390/atoms10010029.
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We investigate the properties of a dilute gas of impurities embedded in an ultracold gas of bosons that forms a Bose–Einstein condensate (BEC). This work focuses mainly on the equation of state (EoS) of the impurity gas at zero temperature and the induced interaction between impurities mediated by the host bath. We use perturbative field-theory approaches, such as Hugenholtz–Pines formalism, in the weakly interacting regime. In turn, for strong interactions, we aim at non-perturbative techniques such as quantum–Monte Carlo (QMC) methods. Our findings agree with experimental observations for an ultra dilute gas of impurities, modeled in the framework of the single impurity problem; however, as the density of impurities increases, systematic deviations are displayed with respect to the one-body Bose polaron problem.
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Agrawal, Poojan, Jarrod Hurley, Simon Stevenson, Dorottya Szécsi, and Chris Flynn. "The fates of massive stars: exploring uncertainties in stellar evolution with metisse." Monthly Notices of the Royal Astronomical Society 497, no. 4 (August 6, 2020): 4549–64. http://dx.doi.org/10.1093/mnras/staa2264.
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ABSTRACT In the era of advanced electromagnetic and gravitational wave detectors, it has become increasingly important to effectively combine and study the impact of stellar evolution on binaries and dynamical systems of stars. Systematic studies dedicated to exploring uncertain parameters in stellar evolution are required to account for the recent observations of the stellar populations. We present a new approach to the commonly used single-star evolution (sse) fitting formulae, one that is more adaptable: method of interpolation for single star evolution (metisse). It makes use of interpolation between sets of pre-computed stellar tracks to approximate evolution parameters for a population of stars. We have used metisse with detailed stellar tracks computed by the modules for experiments in stellar astrophysics (mesa), the bonn evolutionary code (bec), and the Cambridge stars code. metisse better reproduces stellar tracks computed using the stars code compared to sse, and is on average three times faster. Using stellar tracks computed with mesa and bec, we apply metisse to explore the differences in the remnant masses, the maximum radial expansion, and the main-sequence lifetime of massive stars. We find that different physical ingredients used in the evolution of stars, such as the treatment of radiation-dominated envelopes, can impact their evolutionary outcome. For stars in the mass range 9–100 M⊙, the predictions of remnant masses can vary by up to 20 M⊙, while the maximum radial expansion achieved by a star can differ by an order of magnitude between different stellar models.
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Castelao, Renato M., and Patricia M. Medeiros. "Coastal Summer Freshening and Meltwater Input off West Greenland from Satellite Observations." Remote Sensing 14, no. 23 (November 30, 2022): 6069. http://dx.doi.org/10.3390/rs14236069.
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Coastal waters off west Greenland are strongly influenced by the input of low salinity water from the Arctic and from meltwater from the Greenland Ice Sheet. Changes in freshwater content in the region can play an important role in stratification, circulation, and primary production; however, investigating salinity variability in the region is challenging because in situ observations are sparse. Here, we used satellite observations of sea surface salinity (SSS) from the Soil Moisture and Ocean Salinity mission produced by LOCEAN and by the Barcelona Expert Center (SMOS LOCEAN and SMOS BEC) and from the Soil Moisture Active Passive mission produced by the Jet Propulsion Laboratory (SMAP JPL) as well as by Remote Sensing Systems (SMAP RSS) to investigate how variability in a narrow coastal band off west Greenland is captured by these different products. Our analyses revealed that the various satellite SSS products capture the seasonal freshening off west Greenland from late spring to early fall. The magnitudes of the freshening and of coastal salinity gradients vary between the products however, being attenuated compared to historical in situ observations in most cases. The seasonal freshening off southwest Greenland is intensified in SMAP JPL and SMOS LOCEAN near the mouth of fjords characterized by large inputs of meltwater near the surface, which suggests an influence of meltwater from the Greenland Ice Sheet. Synoptic observations from 2012 following large ice sheet melting revealed good agreement with the spatial scale of freshening observed with in situ and SMOS LOCEAN data. Our analyses indicate that satellite SSS can capture the influence of meltwater input and associated freshwater plumes off coastal west Greenland, but those representations differ between products.
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Letscher, R. T., J. K. Moore, Y. C. Teng, and F. Primeau. "Variable C : N : P stoichiometry of dissolved organic matter cycling in the Community Earth System Model." Biogeosciences 12, no. 1 (January 12, 2015): 209–21. http://dx.doi.org/10.5194/bg-12-209-2015.
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Abstract. Dissolved organic matter (DOM) plays an important role in the ocean's biological carbon pump by providing an advective/mixing pathway for ~ 20% of export production. DOM is known to have a stoichiometry depleted in nitrogen (N) and phosphorus (P) compared to the particulate organic matter pool, a fact that is often omitted from biogeochemical ocean general circulation models. However the variable C : N : P stoichiometry of DOM becomes important when quantifying carbon export from the upper ocean and linking the nutrient cycles of N and P with that of carbon. Here we utilize recent advances in DOM observational data coverage and offline tracer-modeling techniques to objectively constrain the variable production and remineralization rates of the DOM C : N : P pools in a simple biogeochemical-ocean model of DOM cycling. The optimized DOM cycling parameters are then incorporated within the Biogeochemical Elemental Cycling (BEC) component of the Community Earth System Model (CESM) and validated against the compilation of marine DOM observations. The optimized BEC simulation including variable DOM C : N : P cycling was found to better reproduce the observed DOM spatial gradients than simulations that used the canonical Redfield ratio. Global annual average export of dissolved organic C, N, and P below 100 m was found to be 2.28 Pg C yr−1 (143 Tmol C yr−1, 16.4 Tmol N yr−1, and 1 Tmol P yr−1, respectively, with an average export C : N : P stoichiometry of 225 : 19 : 1 for the semilabile (degradable) DOM pool. Dissolved organic carbon (DOC) export contributed ~ 25% of the combined organic C export to depths greater than 100 m.
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Letscher, R. T., J. K. Moore, Y. C. Teng, and F. Primeau. "Variable C : N : P stoichiometry of dissolved organic matter cycling in the Community Earth System Model." Biogeosciences Discussions 11, no. 6 (June 16, 2014): 9071–101. http://dx.doi.org/10.5194/bgd-11-9071-2014.
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Abstract. Dissolved organic matter (DOM) plays an important role in the ocean's biological carbon pump by providing an advective/mixing pathway for ~ 20% of export production. DOM is known to have a stoichiometry depleted in nitrogen (N) and phosphorus (P) compared to the particulate organic matter pool, a~fact that is often omitted from biogeochemical-ocean general circulation models. However the variable C : N : P stoichiometry of DOM becomes important when quantifying carbon export from the upper ocean and linking the nutrient cycles of N and P with that of carbon. Here we utilize recent advances in DOM observational data coverage and offline tracer-modeling techniques to objectively constrain the variable production and remineralization rates of the DOM C / N / P pools in a simple biogeochemical-ocean model of DOM cycling. The optimized DOM cycling parameters are then incorporated within the Biogeochemical Elemental Cycling (BEC) component of the Community Earth System Model and validated against the compilation of marine DOM observations. The optimized BEC simulation including variable DOM C : N : P cycling was found to better reproduce the observed DOM spatial gradients than simulations that used the canonical Redfield ratio. Global annual average export of dissolved organic C, N, and P below 100 m was found to be 2.28 Pg C yr−1 (143 Tmol C yr−1), 16.4 Tmol N yr−1, and 1 Tmol P yr−1, respectively with an average export C : N : P stoichiometry of 225 : 19 : 1 for the semilabile (degradable) DOM pool. DOC export contributed ~ 25% of the combined organic C export to depths greater than 100 m.
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Cheng, Xinghong, Zilong Hao, Zengliang Zang, Zhiquan Liu, Xiangde Xu, Shuisheng Wang, Yuelin Liu, Yiwen Hu, and Xiaodan Ma. "A new inverse modeling approach for emission sources based on the DDM-3D and 3DVAR techniques: an application to air quality forecasts in the Beijing–Tianjin–Hebei region." Atmospheric Chemistry and Physics 21, no. 18 (September 16, 2021): 13747–61. http://dx.doi.org/10.5194/acp-21-13747-2021.
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Abstract. We develop a new inversion method which is suitable for linear and nonlinear emission source (ES) modeling, based on the three-dimensional decoupled direct (DDM-3D) sensitivity analysis module in the Community Multiscale Air Quality (CMAQ) model and the three-dimensional variational (3DVAR) data assimilation technique. We established the explicit observation operator matrix between the ES and receptor concentrations and the background error covariance (BEC) matrix of the ES, which can reflect the impacts of uncertainties of the ES on assimilation. Then we constructed the inversion model of the ES by combining the sensitivity analysis with 3DVAR techniques. We performed the simulation experiment using the inversion model for a heavy haze case study in the Beijing–Tianjin–Hebei (BTH) region during 27–30 December 2016. Results show that the spatial distribution of sensitivities of SO2 and NOx ESs to their concentrations, as well as the BEC matrix of ES, is reasonable. Using an a posteriori inversed ES, underestimations of SO2 and NO2 during the heavy haze period are remarkably improved, especially for NO2. Spatial distributions of SO2 and NO2 concentrations simulated by the constrained ES were more accurate compared with an a priori ES in the BTH region. The temporal variations in regionally averaged SO2, NO2, and O3 modeled concentrations using an a posteriori inversed ES are consistent with in situ observations at 45 stations over the BTH region, and simulation errors decrease significantly. These results are of great significance for studies on the formation mechanism of heavy haze, the reduction of uncertainties of the ES and its dynamic updating, and the provision of accurate “virtual” emission inventories for air-quality forecasts and decision-making services for optimization control of air pollution.
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Moore, J. K., and O. Braucher. "Sedimentary and mineral dust sources of dissolved iron to the world ocean." Biogeosciences 5, no. 3 (May 5, 2008): 631–56. http://dx.doi.org/10.5194/bg-5-631-2008.
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Abstract. Analysis of a global compilation of dissolved-iron observations provides insights into the processes controlling iron distributions and some constraints for ocean biogeochemical models. The distribution of dissolved iron appears consistent with the conceptual model developed for Th isotopes, whereby particle scavenging is a two-step process of scavenging mainly by colloidal and small particulates, followed by aggregation and removal on larger sinking particles. Much of the dissolved iron (<0.4 μm) is present as small colloids (>~0.02 μm) and, thus, is subject to aggregation and scavenging removal. This implies distinct scavenging regimes for dissolved iron consistent with the observations: 1) a high scavenging regime – where dissolved-iron concentrations exceed the concentrations of strongly binding organic ligands; and 2) a moderate scavenging regime – where dissolved iron is bound to both colloidal and soluble ligands. Within the moderate scavenging regime, biological uptake and particle scavenging decrease surface iron concentrations to low levels (<0.2 nM) over a wide range of low to moderate iron input levels. Removal rates are also highly nonlinear in areas with higher iron inputs. Thus, observed surface-iron concentrations exhibit a bi-modal distribution and are a poor proxy for iron input rates. Our results suggest that there is substantial removal of dissolved iron from subsurface waters (where iron concentrations are often well below 0.6 nM), most likely due to aggregation and removal on sinking particles of Fe bound to organic colloids. We use the observational database to improve simulation of the iron cycle within a global-scale, Biogeochemical Elemental Cycling (BEC) ocean model. Modifications to the model include: 1) an improved particle scavenging parameterization, based on the sinking mass flux of particulate organic material, biogenic silica, calcium carbonate, and mineral dust particles; 2) desorption of dissolved iron from sinking particles; and 3) an improved sedimentary source for dissolved iron. Most scavenged iron (90%) is put on sinking particles to remineralize deeper in the water column. The model-observation differences are reduced with these modifications. The improved BEC model is used to examine the relative contributions of mineral dust and marine sediments in driving dissolved-iron distributions and marine biogeochemistry. Mineral dust and sedimentary sources of iron contribute roughly equally, on average, to dissolved iron concentrations. The sedimentary source from the continental margins has a strong impact on open-ocean iron concentrations, particularly in the North Pacific. Plumes of elevated dissolved-iron concentrations develop at depth in the Southern Ocean, extending from source regions in the SW Atlantic and around New Zealand. The lower particle flux and weaker scavenging in the Southern Ocean allows the continental iron source to be advected far from sources. Both the margin sediment and mineral dust Fe sources substantially influence global-scale primary production, export production, and nitrogen fixation, with a stronger role for the dust source. Ocean biogeochemical models that do not include the sedimentary source for dissolved iron, will overestimate the impact of dust deposition variations on the marine carbon cycle. Available iron observations place some strong constraints on ocean biogeochemical models. Model results should be evaluated against both surface and subsurface Fe observations in the waters that supply dissolved iron to the euphotic zone.
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Li, Chuang, Nick Houston, Tianjun Li, Qiaoli Yang, and Xin Zhang. "A detailed exploration of the EDGES 21cm absorption anomaly and axion-induced cooling." International Journal of Modern Physics D 30, no. 06 (March 22, 2021): 2150041. http://dx.doi.org/10.1142/s0218271821500413.
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The EDGES collaboration’s observation of an anomalously strong 21 cm absorption feature around the cosmic dawn era has energised the cosmological community by suggesting a novel signature of dark matter in the cooling of cosmic hydrogen. In a recent paper, we have argued that by virtue of the ability to mediate cooling processes whilst in the condensed phase, a small amount of axion dark matter can explain these observations within the context of Standard Models of axions and axion-like particles. These axions and axion-like particles (ALPs) can thermalise through gravitational self-interactions and so eventually form a Bose–Einstein condensate (BEC), whereupon large-scale long-range correlation can produce experimentally observable signals such as these. In this context, the EDGES best-fit result favours an ALP mass in the (6, 400) meV range. Future experiments and galaxy surveys, particularly the International Axion Observatory (IAXO) and EUCLID, should have the capability to directly test this scenario. In this paper, we will explore this mechanism in detail and give more thorough computational details of certain key points.
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Biguino, Beatriz, Estrella Olmedo, Afonso Ferreira, Nuno Zacarias, Luísa Lamas, Luciane Favareto, Carla Palma, et al. "Evaluation of SMOS L4 Sea Surface Salinity Product in the Western Iberian Coast." Remote Sensing 14, no. 2 (January 17, 2022): 423. http://dx.doi.org/10.3390/rs14020423.
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Salinity is one of the oldest parameters being measured in oceanography and one of the most important to study in the context of climate change. However, its quantification by satellite remote sensing has been a relatively recent achievement. Currently, after over ten years of data gathering, there are still many challenges in quantifying salinity from space, especially when it is intended for coastal environments study. That is mainly due to the spatial resolution of the available products. Recently, a new higher resolution (5 km) L4 SMOS sea surface salinity (SSS) product was developed by the Barcelona Expert Center (BEC). In this study, the quality of this product was tested along the Western Iberian Coast through its comparison with in situ observations and modelled salinity estimates (CMEMS IBI Ocean Reanalysis system). Moreover, several parameters such as the temperature and depth of in situ measurements were tested to identify the variables or processes that induced higher errors in the product or influenced its performance. Lastly, a seasonal and interannual analysis was conducted considering data between 2011 to 2019 to test the product as a potential tool for long-term studies. The results obtained in the present analysis showed a high potential of using the L4 BEC SSS SMOS product in extended temporal and spatial analyses along the Portuguese coast. A good correlation between the satellite and the in situ datasets was observed, and the satellite dataset showed lower errors in retrieving coastal salinities than the oceanic model. Overall, the distance to the coast and the closest rivers were the factors that most influenced the quality of the product. The present analysis showed that great progress has been made in deriving coastal salinity over the years and that the SMOS SSS product is a valuable contribution to worldwide climatological studies. In addition, these results reinforce the need to continue developing satellite remote sensing products as a global and cost-effective methodology for long-term studies.
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Moore, J. K., and O. Braucher. "Sedimentary and mineral dust sources of dissolved iron to the World Ocean." Biogeosciences Discussions 4, no. 2 (April 25, 2007): 1279–327. http://dx.doi.org/10.5194/bgd-4-1279-2007.
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Abstract. A worldwide database of dissolved iron observations is used to improve simulations of the marine iron cycle within a global-scale, Biogeochemical Elemental Cycling (BEC) ocean model. Modifications to the model include: 1) an improved particle scavenging parameterization based on the sinking mass flux of particulate organic material, biogenic silica, calcium carbonate, and mineral dust particles; 2) desorption of dissolved iron from sinking particles; and 3) an improved sedimentary source for dissolved iron. Most scavenged iron (90%) is put on sinking particles to remineralize deeper in the water column. The model-observation mismatches are greatly reduced both in surface waters and in the deeper ocean. Inclusion of desorption has little effect on surface water iron concentrations where adsorption/scavenging is strongly dominant, but significantly increases simulated iron concentrations in the deep ocean. Our results suggest that there must be substantial removal of dissolved iron from subsurface waters (where iron concentrations are <0.6 nM in most regions) to match observed distributions. Aggregation and removal on sinking particles of Fe bound to organic colloids is a likely mechanism. The improved BEC model is used to address the relative contributions of mineral dust and marine sediments in driving ocean productivity and observed dissolved iron distributions. The sedimentary iron source from the continental margins has a strong impact on open ocean iron concentrations, particularly in the North Pacific. Plumes of elevated dissolved iron concentrations develop at depth in the Southern Ocean, extending from source regions in the SW Atlantic and around New Zealand. The lower particle flux and weaker scavenging in this region allows the continental iron source to be advected far from source areas. Both the margin sediment and mineral dust Fe sources significantly impact global scale primary production, export production, and nitrogen fixation, with inputs from dust deposition having a modestly stronger impact. Ocean biogeochemical models need to include the sedimentary source for dissolved iron, or they will overestimate the impact of dust deposition variations on the marine carbon cycle.
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Sivakumar, Ramu, Neelam Sharma-Walia, Hari Raghu, Mohanan Valiya Veettil, Sathish Sadagopan, Virginie Bottero, Laszlo Varga, Rita Levine, and Bala Chandran. "Kaposi's Sarcoma-Associated Herpesvirus Induces Sustained Levels of Vascular Endothelial Growth Factors A and C Early during In Vitro Infection of Human Microvascular Dermal Endothelial Cells: Biological Implications." Journal of Virology 82, no. 4 (December 5, 2007): 1759–76. http://dx.doi.org/10.1128/jvi.00873-07.
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ABSTRACT Kaposi's sarcoma (KS), a vascular tumor associated with human immunodeficiency virus type 1 infection, is characterized by spindle-shaped endothelial cells, inflammatory cells, cytokines, growth and angiogenic factors, and angiogenesis. KS spindle cells are believed to be of the lymphatic endothelial cell (LEC) type. Kaposi's sarcoma-associated herpesvirus (KSHV, or human herpesvirus 8) is etiologically linked to KS, and in vitro KSHV infection of primary human dermal microvascular endothelial cells (HMVEC-d) is characterized by the induction of preexisting host signal cascades, sustained expression of latency-associated genes, transient expression of a limited number of lytic genes, sustained induction of NF-κB and several cytokines, and growth and angiogenic factors. KSHV induced robust vascular endothelial growth factor A (VEGF-A) and VEGF-C gene expression as early as 30 min postinfection (p.i.) in serum-starved HMVEC-d, which was sustained throughout the observation period of 72 h p.i. Significant amounts of VEGF-A and -C were also detected in the culture supernatant of infected cells. VEGF-A and -C were also induced by UV-inactivated KSHV and envelope glycoprotein gpK8.1A, thus suggesting a role for virus entry stages in the early induction of VEGF and requirement of KSHV viral gene expression for sustained induction. Exogenous addition of VEGF-A and -C increased KSHV DNA entry into target cells and moderately increased latent ORF73 and lytic ORF50 promoter activation and gene expression. KSHV infection also induced the expression of lymphatic markers Prox-1 and podoplanin as early as 8 h p.i., and a paracrine effect was seen in the neighboring uninfected cells. Similar observations were also made in the pure blood endothelial cell (BEC)-TIME cells, thus suggesting that commitment to the LEC phenotype is induced early during KSHV infection of blood endothelial cells. Treatment with VEGF-C alone also induced Prox-1 expression in the BEC-TIME cells. Collectively, these studies show that the in vitro microenvironments of KSHV-infected endothelial cells are enriched, with VEGF-A and -C molecules playing key roles in KSHV biology, such as increased infection and gene expression, as well as in angiogenesis and lymphangiogenesis, thus recapitulating the microenvironment of early KS lesions.
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Aulicino, Giuseppe, Yuri Cotroneo, Estrella Olmedo, Cinzia Cesarano, Giannetta Fusco, and Giorgio Budillon. "In Situ and Satellite Sea Surface Salinity in the Algerian Basin Observed through ABACUS Glider Measurements and BEC SMOS Regional Products." Remote Sensing 11, no. 11 (June 6, 2019): 1361. http://dx.doi.org/10.3390/rs11111361.
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The Algerian Basin is a key area for the general circulation in the western Mediterranean Sea. The basin has an intense inflow/outflow regime with complex circulation patterns, involving both fresh Atlantic water and more saline Mediterranean water. Several studies have demonstrated the advantages of the combined use of autonomous underwater vehicles, such as gliders, with remotely sensed products (e.g., altimetry, MUR SST) to observe meso- and submesoscale structures and their properties. An important contribution could come from a new generation of enhanced satellite sea surface salinity (SSS) products, e.g., those provided by the Soil Moisture and Ocean Salinity (SMOS) mission. In this paper, we assess the advantages of using Barcelona Expert Center (BEC) SMOS SSS products, obtained through a combination of debiased non-Bayesian retrieval, DINEOF (data interpolating empirical orthogonal functions) and multifractal fusion with high resolution sea surface temperature (OSTIA SST) maps. Such an aim was reached by comparing SMOS Level-3 (L3) and Level-4 (L4) SSS products with in situ high resolution glider measurements collected in the framework of the Algerian Basin Circulation Unmanned Survey (ABACUS) observational program conducted in the Algerian Basin during falls 2014–2016. Results show that different levels of confidence between in situ and satellite measurements can be achieved according to the spatial scales of variability. Although SMOS values slightly underestimate in situ observations (mean difference is −0.14 (−0.11)), with a standard deviation of 0.25 (0.26) for L3 (L4) products), at basin scale, the enhanced SMOS products well represent the salinity patterns described by the ABACUS data.
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Moore, J. K., and O. Braucher. "Observations of dissolved iron concentrations in the World Ocean: implications and constraints for ocean biogeochemical models." Biogeosciences Discussions 4, no. 2 (April 25, 2007): 1241–77. http://dx.doi.org/10.5194/bgd-4-1241-2007.
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Abstract. Analysis of a global compilation of dissolved iron observations provides insights into the controlling processes for iron distributions and some constraints for ocean biogeochemical models. The distribution of dissolved iron is consistent with the conceptual model developed for the scavenging of Th isotopes, whereby particle scavenging is a two-step process of scavenging mainly by colloidal and small particulates followed by aggregation and removal on larger sinking particles. Much of the dissolved iron (<0.4 μm) is present as small colloids (>~0.02 μm) and, thus, likely subject to aggregation and scavenging removal. Only the iron bound to soluble ligands (<~0.02 μm) is likely protected from scavenging removal. This implies distinct scavenging regimes for dissolved iron that appear consistent with the observational data: 1) high scavenging regime – where dissolved iron concentrations exceed the concentrations of strongly binding organic ligands; and 2) moderate scavenging regime – where dissolved iron is bound to both colloidal and soluble ligands. The removal rates for dissolved iron will be a function of biological uptake, number and size distributions of the colloidal and small particulate material, ligand dynamics, and the aggregation processes that lead to removal on larger particles. Inputs from dust deposition and continental sediments are key drivers of dissolved iron distributions. The observations provide several strong constraints for ocean biogeochemical models: 1) similar deep ocean concentrations in the North Atlantic and North Pacific (~0.6–0.8 nM), and much lower deep ocean dissolved iron concentrations in the Southern Ocean (~0.3–0.4 nM); 2) strong depletion of iron in the upper ocean away from the high dust deposition regions, with significant scavenging removal of dissolved iron below the euphotic zone; and 3) a bimodal distribution in surface waters with peaks less than 0.2 nM and between 0.6–0.8 nM. We compare the dissolved iron observations with output from the Biogeochemical Elemental Cycling (BEC) ocean model. The model output was in general agreement with the field data (r=0.76, for depths 103–502 m), but at lower iron concentrations (<0.3 nM) the model is consistently biased high relative to the observations.
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Lima, I. D., P. J. Lam, and S. C. Doney. "Dynamics of particulate organic carbon flux in a global ocean model." Biogeosciences 11, no. 4 (February 27, 2014): 1177–98. http://dx.doi.org/10.5194/bg-11-1177-2014.
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Abstract. The sinking of particulate organic carbon (POC) is a key component of the ocean carbon cycle and plays an important role in the global climate system. However, the processes controlling the fraction of primary production that is exported from the euphotic zone (export ratio) and how much of it survives respiration in the mesopelagic to be sequestered in the deep ocean (transfer efficiency) are not well understood. In this study, we use a three-dimensional, coupled physical–biogeochemical model (CCSM–BEC; Community Climate System Model–ocean Biogeochemical Elemental Cycle) to investigate the processes controlling the export of particulate organic matter from the euphotic zone and its flux to depth. We also compare model results with sediment trap data and other parameterizations of POC flux to depth to evaluate model skill and gain further insight into the causes of error and uncertainty in POC flux estimates. In the model, export ratios are mainly a function of diatom relative abundance and temperature while absolute fluxes and transfer efficiency are driven by mineral ballast composition of sinking material. The temperature dependence of the POC remineralization length scale is modulated by denitrification under low O2 concentrations and lithogenic (dust) fluxes. Lithogenic material is an important control of transfer efficiency in the model, but its effect is restricted to regions of strong atmospheric dust deposition. In the remaining regions, CaCO3 content of exported material is the main factor affecting transfer efficiency. The fact that mineral ballast composition is inextricably linked to plankton community structure results in correlations between export ratios and ballast minerals fluxes (opal and CaCO3), and transfer efficiency and diatom relative abundance that do not necessarily reflect ballast or direct ecosystem effects, respectively. This suggests that it might be difficult to differentiate between ecosystem and ballast effects in observations. The model's skill in reproducing sediment trap observations is equal to or better than that of other parameterizations. However, the sparseness and relatively large uncertainties of sediment trap data makes it difficult to accurately evaluate the skill of the model and other parameterizations. More POC flux observations, over a wider range of ecological regimes, are necessary to thoroughly evaluate and test model results and better understand the processes controlling POC flux to depth in the ocean.
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Lima, I. D., P. J. Lam, and S. C. Doney. "Dynamics of particulate organic carbon flux in a global ocean model." Biogeosciences Discussions 10, no. 9 (September 6, 2013): 14715–67. http://dx.doi.org/10.5194/bgd-10-14715-2013.
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Abstract. The sinking of particulate organic carbon (POC) is a key component of the ocean carbon cycle and plays an important role in the global climate system. However, the processes controlling the fraction of primary production that is exported from the euphotic zone (export ratio) and how much of it survives respiration in the mesopelagic to be sequestered in the deep ocean (transfer efficiency) are not well understood. In this study, we use a three-dimensional, coupled physical-biogeochemical model (CCSM-BEC) to investigate the processes controlling the export of particulate organic matter from the euphotic zone and its flux to depth. We also compare model results with sediment trap data and other parameterizations of POC flux to depth to evaluate model skill and gain further insight into the causes of error and uncertainty in POC flux estimates. In the model, export ratios are mainly a function of diatom relative abundance and temperature while absolute fluxes and transfer efficiency are driven by mineral ballast composition of sinking material. The temperature dependence of the POC remineralization length scale is modulated by denitrification under low O2 concentrations and lithogenic (dust) fluxes. Lithogenic material is an important control of transfer efficiency in the model, but its effect is restricted to regions of strong atmospheric dust deposition. In the remaining regions, CaCO3 content of exported material is the main factor affecting transfer efficiency. The fact that mineral ballast composition is inextricably linked to plankton community structure results in correlations between export ratios and ballast minerals fluxes (opal and CaCO3), and transfer efficiency and diatom relative abundance that do not necessarily reflect ballast or direct ecosystem effects, respectively. This suggests that it might be difficult to differentiate between ecosystem and ballast effects in observations. The model's skill at reproducing sediment trap observations is equal to or better than that of other parameterizations. However, the sparseness and relatively large uncertainties of sediment trap data makes it difficult to accurately evaluate the skill of the model and other parameterizations. More POC flux observations, over a wider range of ecological regimes, are necessary to thoroughly evaluate and test model results and better understand the processes controlling POC flux to depth in the ocean.
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Keats, Jonathan, Mike Chapman, John Carpten, Wee-Joo Chng, Angela Baker, Gregory Ahmann, Suzanne Trudel, et al. "Genomc-Wide Profiling of Gene Expression and DNA Copy Number Alterations in Multiple Myeloma." Blood 110, no. 11 (November 16, 2007): 396. http://dx.doi.org/10.1182/blood.v110.11.396.396.
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Abstract In an effort to identify novel genetic abnormalities in multiple myeloma (MM) we analyzed an initial set, as part of the Multiple Myeloma Research Consortium (MMRC) Genomics Initiative, of 94 MM patient samples on high-resolution array-based comparative genomic hybridization (aCGH) and gene expression profiling (GEP) technologies. The MMRC Genomics Initiative is a three-year research program spanning a full-spectrum of genomic technologies with the goal of analyzing 250 MM patient samples by 2009. Raw data from the Initiative are released in near real time through the MMRC Multiple Myeloma Genomics Portal. This initial aCGH dataset from the Agilent 244K platform represents the highest resolution gene copy number analysis with corresponding GEP released to date in MM. It has confirmed the cytogenetic definitions of MM with the data set being split between patients with hyperdiploid and non-hyperdiploid MM. Furthermore, the 244K platform has helped to refine minimal regions of change present on 1p, 1q, 6q, 8p, 13q, 14q, and 16q. A comprehensive screen of the dataset for genes residing in regions of homozygous deletion identified 105 genes. The most commonly affected gene was CDKN2C(p18) (8.3%) while 12 other regions were recurrently targeted. Several of these regions were recently implicated in the pathogenesis of MM but the large majority represents novel observations. The aCGH and GEP data were integrated using two different programs developed by the core institutions (The Broad Institute of Harvard & MIT and Translational Genomics Research Institute). First, Genomic Identification of Significant Targets in Cancer (GISTIC), which identifies highly significant regions of change and a limited set of candidate genes within these regions, was used to identify 285 genes associated with DNA content alterations. Second, Breakpoint Expression Correlation (BEC), which identifies dysregulated genes on either side of a copy number alteration, was used to identify 194 genes with expression changes associated with a breakpoint. This latter gene list includes all known IgH translocation target genes identified to date in myeloma. Overlapping the gene lists generated by GISTIC, BEC, and the homozygous deletion screen identified a number of genes previously implicated in MM such as CDKN2C(p18), CYLD, BIRC2/BIRC3, and two novel genes, FAM46C and RNF6. Ongoing data integration with RNAi and high content sequencing projects of the current Initiative holds great promise in furthering our understanding of MM. The MMRC Genomics Initiative and resulting efforts from the myeloma research community will increase our understanding of MM at the molecular level, help to identify new targets, and ultimately lead to the development of better, more effective therapies for myeloma.
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Hudon, G., R. Laprise, and L. Guindon. "46. Did the CME/CPD train leave with half the passengers? A needs assessment of Québec specialist associations' CPD units." Clinical & Investigative Medicine 30, no. 4 (August 1, 2007): 52. http://dx.doi.org/10.25011/cim.v30i4.2806.
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This presentation reports on the results of a needs assessment conducted amongst the 34 Quebec specialist associations, which are accredited as CME/CPD providers by Quebec’s College of Physicians, in accordance with the Canadian Association of Continuing Medical Education’s criteria.
In 2006, a mix of methods (survey, semi-structured interviews and program documentation review) were used to assess CPD units’ learning needs in the areas of CME and CPD, the extent to which they carried out a list of specific tasks associated to providers’ responsibilities, barriers encountered in meeting standards, and the kind of help needed to improve performance.
Although CME/CPD fields have evolved considerably in the past 20 years, results indicate that few of the advances have made their way down to the associations. The majority still provides education in the form of traditional CME, where speakers talk about new developments in medicine. Whereas the systematic approach of CME is well integrated in most units, few go beyond perceptions in their needs assessments, use problem-based learning methods, enablers, reinforcement and outcome evaluations, or help specialists self-evaluate and reflect on their practice. These methods and approaches are believed to increase CME effectiveness.
Most Canadian specialists get a large proportion of their CE from non academic medical organizations such as professional associations and learned societies. However, information available in the literature does not allow generalization of our observations to other organizations of this nature. Since non academic organizations are important CME/CPD providers, we propose that more attention be given on the way trainers are trained and innovations are shared in our CE system. What minimal knowledge and skills should be required of a CME/CPD professional today? Together with its affiliated associations and academic partners, the Federation of Medical Specialists of Quebec (FMSQ) has decided to tackle this important issue in the coming years.
Olson CA, Tooman TR, Leist JC. Contents of a core library in continuing medical education: a delphi study. JCEHP 2005; 25:278-88.
Davis DA, Thomson MA, Oxman AD, Haynes RB. Changing physician performance: a systematic review of the effect of continuing medical education strategies. JAMA 1995; 274:700-5.
Grol R, Grimshaw J. From best evidence to best practice: effective implementation of change in patients' care. Lancet 2003; 362:1225-30.
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Crête, Michel, Louis-Paul Rivest, Didier Le Hénaff, and Stuart N. Luttich. "Adapting sampling plans to caribou distribution on calving grounds." Rangifer 11, no. 4 (October 1, 1991): 137. http://dx.doi.org/10.7557/2.11.4.1004.
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Between 1984 and 1988, the size of the two caribou herds in northern Québec was derived by combining estimates of female numbers on calving grounds in June and composition counts during rut in autumn. Sampling with aerial photos was conducted on calving grounds to determine the number of animals per km2, telemetry served to estimate the proportion of females in the census area at the time of photography in addition to summer survival rate, and helicopter or ground observations were used for composition counts. Observers were able to detect on black and white negatives over 95 percent of caribou counted from a helicopter flying at low altitude over the same area; photo scale varied between = 1:3 600 and 1:6 000. Sampling units covering less than 15-20 ha were the best for sampling caribou distribution on calving grounds, where density generally averaged » 10 individuals-km"2. Around 90 percent of caribou on calving grounds were females; others were mostly yearling males. During the 1-2 day photographic census, 64 to 77 percent of the females were present on the calving areas. Summer survival exceeded 95 percent in three summers. In autumn, females composed between 45 and 54 percent of each herd. The Rivière George herd was estimated at 682 000 individuals (± 36%; alpha = 0.10) in 1988. This estimate was imprecise due to insufficiens sample size for measuring animal density on the calving ground and for determining proportion of females on the calving ground at the time of the photo census. To improve precision and reduce cost, it is proposed to estimate herd size of tundra caribou in one step, using only aerial photos in early June without telemetry.
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Herbert, Christoph, Miriam Pablos, Mercè Vall-llossera, Adriano Camps, and José Martínez-Fernández. "Analyzing Spatio-Temporal Factors to Estimate the Response Time between SMOS and In-Situ Soil Moisture at Different Depths." Remote Sensing 12, no. 16 (August 13, 2020): 2614. http://dx.doi.org/10.3390/rs12162614.
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A comprehensive understanding of temporal variability of subsurface soil moisture (SM) is paramount in hydrological and agricultural applications such as rainfed farming and irrigation. Since the SMOS (Soil Moisture and Ocean Salinity) mission was launched in 2009, globally available satellite SM retrievals have been used to investigate SM dynamics, based on the fact that useful information about subsurface SM is contained in their time series. SM along the depth profile is influenced by atmospheric forcing and local SM properties. Until now, subsurface SM was estimated by weighting preceding information of remotely sensed surface SM time series according to an optimized depth-specific characteristic time length. However, especially in regions with extreme SM conditions, the response time is supposed to be seasonally variable and depends on related processes occurring at different timescales. Aim of this study was to quantify the response time by means of the time lag between the trend series of satellite and in-situ SM observations using a Dynamic Time Warping (DTW) technique. DTW was applied to the SMOS satellite SM L4 product at 1 km resolution developed by the Barcelona Expert Center (BEC), and in-situ near-surface and root-zone SM of four representative stations at multiple depths, located in the Soil Moisture Measurements Station Network of the University of Salamanca (REMEDHUS) in Western Spain. DTW was customized to control the rate of accumulation and reduction of time lag during wetting and drying conditions and to consider the onset dates of pronounced precipitation events to increase sensitivity to prominent features of the input series. The temporal variability of climate factors in combination with crop growing seasons were used to indicate prevailing SM-related processes. Hereby, a comparison of long-term precipitation recordings and estimations of potential evapotranspiration (PET) allowed us to estimate SM seasons. The spatial heterogeneity of land use was analyzed by means of high-resolution images of Normalized Difference Vegetation Index (NDVI) from Sentinel-2 to provide information about the level of spatial representativeness of SMOS observations to each in-situ station. Results of the spatio-temporal analysis of the study were then evaluated to understand seasonally and spatially changing patterns in time lag. The time lag evolution describes a variable characteristic time length by considering the relevant processes which link SMOS and in-situ SM observation, which is an important step to accurately infer subsurface SM from satellite time series. At a further stage, the approach needs to be applied to different SM networks to understand the seasonal, climate- and site-specific characteristic behaviour of time lag and to decide, whether general conclusions can be drawn.
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Wang, S., D. Bailey, K. Lindsay, K. Moore, and M. Holland. "Impacts of sea ice on the marine iron cycle and phytoplankton productivity." Biogeosciences Discussions 11, no. 2 (February 11, 2014): 2383–418. http://dx.doi.org/10.5194/bgd-11-2383-2014.
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Abstract. Iron is a key nutrient for phytoplankton growth in the surface ocean. At high latitudes, the iron cycle is closely related to sea ice. In recent decades, Arctic sea ice cover has been declining rapidly and Antarctic sea ice has exhibited large regional trends. A significant reduction of sea ice in both hemispheres is projected in future climate scenarios. To study impacts of sea ice on the iron cycle, iron sequestration in ice is incorporated to the Biogeochemical Elemental Cycling (BEC) model. Sea ice acts as a reservoir of iron during winter and releases iron to the surface ocean in spring and summer. Simulated iron concentrations in sea ice generally agree with observations, in regions where iron concentrations are lower. The maximum iron concentrations simulated in the Arctic sea ice and the Antarctic sea ice are 192 nM and 134 nM, respectively. These values are much lower than observed, which is likely due to missing biological processes in sea ice. The largest iron source to sea ice is suspended sediments, contributing fluxes of iron of 2.2 × 108 mol Fe month−1 to the Arctic and 4.1 × 106 mol Fe month−1 to the Southern Ocean during summer. As a result of the iron flux from ice, iron concentrations increase significantly in the Arctic. Iron released from melting ice increases phytoplankton production in spring and summer and shifts phytoplankton community composition in the Southern Ocean. Simulation results for the period of 1998 to 2007 indicate that a reduction of sea ice in the Southern Ocean will have a negative influence on phytoplankton production. Iron transport by sea ice appears to be an important process bringing iron to the central Arctic. Impacts of iron fluxes from ice to ocean on marine ecosystems are negligible in the current Arctic Ocean, as iron is not typically the growth-limiting nutrient. However, it may become a more important factor in the future, particularly in the central Arctic, as iron concentrations will decrease with declining sea ice cover and transport.
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Michael E. Akresh, Steven Lamonde, Lillian Stokes, Cody M. Kent, Frank Kahoun, and Janet M. Clarke Storr. "A review of wood warbler (Parulidae) predation of vertebrates and descriptions of three new observations." Journal of Caribbean Ornithology 35 (May 10, 2022): 29–39. http://dx.doi.org/10.55431/jco.2022.35.29-39.
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Abstract Wood warblers (Parulidae) eat insects, spiders and other small arthropods, fruit, and nectar, but have also been documented preying on vertebrates. We conducted a literature review to determine which species of Parulidae have been observed capturing or consuming vertebrate species, such as small lizards, amphibians, and fish. We also include information and discussion of three previously unpublished observations: 1) a Black-and-white Warbler (Mniotilta varia) photographed with a bark anole (Anolis distichus) in its mouth on San Salvador Island, The Bahamas, 2) a Black-and-white Warbler that had small lizard bones (Anolis spp.) in its stomach contents in Jamaica, and 3) a Yellow-throated Warbler (Setophaga dominica) photographed preying on a brown anole (Anolis sagrei) in Florida, USA. The latter observation was particularly interesting as the brown anole shed its tail and briefly escaped before being recaptured by the warbler. Including these three unpublished events, our literature review found 24 separate records of 12 Parulidae species preying on vertebrates. The majority of predation records were of lizards (58%), with an additional 25% predation records of amphibians and 17% of fish. We hypothesize that vertebrate predation by wood warblers is opportunistic and potentially limited by the difficulty in capturing, handling, and consuming larger vertebrate prey. There is also non-mutually exclusive evidence to suggest birds exhibit plasticity in prey items, partially switching to larger, more difficult-to-handle vertebrate prey during taxing periods when invertebrate prey are less available. Our study synthesizes previous work and can assist future research in better understanding trophic interactions, foraging efficiency and prey size, evolution, and the natural history of both warblers and their vertebrate prey.
Keywords bird diet, caudal autotomy, foraging efficiency, non-breeding, predatory behavior, Squamata
Resumen Revisión de la depredación de vertebrados por parte de parúlidos (Parulidae) y descripción de tres nuevas observaciones • Los parúlidos (Parulidae) se alimentan de insectos, arañas y otros pequeños artrópodos, frutas y néctar; pero también se ha documentado que depredan vertebrados. Realizamos una revisión bibliográfica para determinar qué especies de Parulidae han sido observadas capturando o consumiendo especies de vertebrados, como pequeños lagartos, anfibios y peces. También incluimos información y discutimos tres observaciones inéditas: 1) un individuo de Mniotilta varia fotografiado con un lagarto de la especie Anolis distichus en el pico en la isla de San Salvador, Bahamas, 2) otro individuo de Mniotilta varia que tenía pequeños huesos de Anolis spp. en su contenido estomacal en Jamaica, y 3) un indidividuo de Setophaga dominica fotografiado mientras depredaba a otro de Anolis sagrei en Florida, Estados Unidos. Esta última observación fue especialmente interesante, ya que el lagarto soltó la cola y escapó brevemente antes de ser recapturado por el ave. Incluyendo estos tres eventos no publicados, en nuestra revisión de la literatura encontramos 24 registros separados de 12 especies de Parulidae que cazan vertebrados. La mayoría de los registros de depredación fueron de lagartos (58%), mientras que otro 25% se correspondió con anfibios y un 17% con peces. Nuestra hipótesis es que la depredación de vertebrados por parte de parúlidos es oportunista y potencialmente limitada por la dificultad de capturar, manipular y consumir presas vertebradas de mayor tamaño. También existen evidencias no excluyentes que sugieren que las aves muestran plasticidad en sus presas y pueden cambiar parcialmente a presas vertebradas de mayor tamaño y más difíciles de manejar durante los periodos más exigentes, en los que las presas invertebradas están menos disponibles. Nuestro estudio resume trabajos anteriores y puede ayudar en futuras investigaciones a comprender mejor las interacciones tróficas, la eficiencia de forrajeo y el tamaño de las presas, la evolución y la historia natural tanto de los parúlidos como de sus presas vertebradas.
Palabras clave autotomía caudal, conducta depredadora, dieta de las aves, eficiencia de forrajeo, no reproductivo, Squamata
Résumé Examen de la prédation des vertébrés par les parulines (Parulidae) et description de trois nouvelles observations • Les parulines (Parulidae) se nourrissent d’insectes, d’araignées et d’autres petits arthropodes ainsi que de fruits et de nectar, mais il a aussi été constaté qu’elles peuvent s’attaquer aux vertébrés. Nous avons réalisé une étude bibliographique pour déterminer quelles espèces de Parulidae ont été observées capturant ou consommant des vertébrés, tels que des lézards, des amphibiens et des poissons de petite taille. Nous incluons également des informations et une discussion sur trois observations inédites : 1) une Paruline noir et blanc (Mniotilta varia) photographiée avec dans le bec un anolis (Anolis distichus), sur l’île de San Salvador, aux Bahamas ; 2) une Paruline noir et blanc dont l’estomac contenait des os de petits anolis (Anolis spp.), en Jamaïque ; et 3) une Paruline à gorge jaune (Setophaga dominica) photographiée en train de capturer un anolis brun (Anolis sagrei) en Floride, aux États-Unis. Cette dernière observation était particulièrement intéressante, car l’anolis brun a perdu sa queue et s’est brièvement échappé avant d’être repris par la paruline. En incluant ces trois observations non publiées, notre étude bibliographique fait état de 24 enregistrements distincts de 12 espèces de Parulidae capturant des vertébrés. Les mentions de prédation concernaient majoritairement des lézards (58 %), mais aussi des amphibiens (25 %) et des poissons (17 %). Nous supposons que la prédation des vertébrés par les parulines est opportuniste et potentiellement limitée par la difficulté à capturer, manipuler et consommer des proies vertébrées plus grandes. Il existe également des éléments non mutuellement exclusifs qui indiquent que les oiseaux font preuve de plasticité dans le choix de leurs proies, se tournant partiellement vers des proies vertébrées plus grandes et plus difficiles à manipuler lors des périodes où les proies invertébrées sont moins disponibles. Notre étude synthétise les travaux antérieurs et pourra aider les recherches futures à mieux comprendre les interactions trophiques, l’efficacité de la recherche de nourriture et la taille des proies, l’évolution et le cycle de vie des parulines et de leurs proies vertébrées.
Mots clés
autotomie caudale, comportement de prédation, efficacité de la recherche de nourriture, espèce non nicheuse, régime alimentaire des oiseaux, Squamata
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Bhattacherjee, Aranya, and Monika Pietrzyk. "Transport behaviour of a Bose Einstein condensate in a bichromatic optical lattice." Open Physics 6, no. 1 (January 1, 2008). http://dx.doi.org/10.2478/s11534-008-0036-y.
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AbstractWe investigate the Bloch and dipole oscillations of a Bose Einstein condensate (BEC) in an optical superlattice. We show that, as the effective mass increases in an optical superlattice, the BEC is localized in accordance with recent experimental observations [J.E. Lye et. al. Phys. Rev. A 75, 061603 (2007)]. In addition, we find that the secondary optical lattice is a useful additional tool to manipulate the dynamics of the atoms.
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Sun, Tao, Juanzhen Sun, Yaodeng Chen, Ying Zhang, Zhuming Ying, and Haiqin Chen. "Improving Short-term Precipitation Forecasting with Radar Data Assimilation and a Multiscale Hybrid Ensemble-Variational Strategy." Monthly Weather Review, June 7, 2022. http://dx.doi.org/10.1175/mwr-d-21-0325.1.
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Abstract This paper presents a multiscale hybrid ensemble-variational (EnVar) data assimilation strategy with an hourly rapid update aiming to improve analysis of convection via radar observations and of convective environment via conventional observations. In this multiscale hybrid EnVar strategy, the ensemble members are updated by assimilating conventional data using an EnKF to provide the hybrid EnVar with flow-dependent background error covariance (BEC). A two-step approach is employed in the hybrid EnVar to achieve improved multiscale analysis by assimilating radar data and conventional data, respectively, in two successive steps. This two-step procedure enables the applications of different BEC tuning factors and different hybrid weights for radar and conventional observations. In addition, this study also examines the impacts of the flow-dependent BEC generated with/without radar data assimilation in EnKF on the performance of hybrid EnVar analysis and ensuing convective forecasting. The multiscale hybrid EnVar strategy was first evaluated through a comparison with 3DVar and EnKF using a convective rainfall case. Quantitative verifications for both precipitation and environmental variables demonstrated that the hybrid EnVar system with an optimal multiscale configuration outperformed both the 3DVar and EnKF. The multiscale hybrid EnVar strategy was then evaluated through a series of sensitivity experiments. It was shown that the two-step assimilation strategy outperformed the one-step for both the precipitation and environmental variables, and the ensemble BEC generated without radar data assimilation led to improved hybrid EnVar analysis over that with radar data assimilation by better representing uncertainties in convective environment and reducing spurious spatial and multivariate correlations.
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Jeong, Donghyun Paul, Eva Hall, Erin Neu, and Donny Hanjaya-Putra. "Podoplanin is Responsible for the Distinct Blood and Lymphatic Capillaries." Cellular and Molecular Bioengineering, August 6, 2022. http://dx.doi.org/10.1007/s12195-022-00730-2.
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Abstract Introduction Controlling the formation of blood and lymphatic vasculatures is crucial for engineered tissues. Although the lymphatic vessels originate from embryonic blood vessels, the two retain functional and physiological differences even as they develop in the vicinity of each other. This suggests that there is a previously unknown molecular mechanism by which blood (BECs) and lymphatic endothelial cells (LECs) recognize each other and coordinate to generate distinct capillary networks. Methods We utilized Matrigel and fibrin assays to determine how cord-like structures (CLS) can be controlled by altering LEC and BEC identity through podoplanin (PDPN) and folliculin (FLCN) expressions. We generated BECΔFLCN and LECΔPDPN, and observed cell migration to characterize loss lymphatic and blood characteristics due to respective knockouts. Results We observed that LECs and BECs form distinct CLS in Matrigel and fibrin gels despite being cultured in close proximity with each other. We confirmed that the LECs and BECs do not recognize each other through paracrine signaling, as proliferation and migration of both cells were unaffected by paracrine signals. On the other hand, we found PDPN to be the key surface protein that is responsible for LEC-BEC recognition, and LECs lacking PDPN became pseudo-BECs and vice versa. We also found that FLCN maintains BEC identity through downregulation of PDPN. Conclusions Overall, these observations reveal a new molecular pathway through which LECs and BECs form distinct CLS through physical contact by PDPN which in turn is regulated by FLCN, which has important implications toward designing functional engineered tissues.
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Ferreira, Elisa G. M. "Ultra-light dark matter." Astronomy and Astrophysics Review 29, no. 1 (September 9, 2021). http://dx.doi.org/10.1007/s00159-021-00135-6.
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AbstractUltra-light dark matter is a class of dark matter models (DM), where DM is composed by bosons with masses ranging from $$10^{-24}\, \mathrm {eV}< m < \mathrm {eV}$$ 10 - 24 eV < m < eV . These models have been receiving a lot of attention in the past few years given their interesting property of forming a Bose–Einstein condensate (BEC) or a superfluid on galactic scales. BEC and superfluidity are some of the most striking quantum mechanical phenomena that manifest on macroscopic scales, and upon condensation, the particles behave as a single coherent state, described by the wavefunction of the condensate. The idea is that condensation takes place inside galaxies while outside, on large scales, it recovers the successes of $$\varLambda $$ Λ CDM. This wave nature of DM on galactic scales that arise upon condensation can address some of the curiosities of the behaviour of DM on small-scales. There are many models in the literature that describe a DM component that condenses in galaxies. In this review, we are going to describe those models, and classify them into three classes, according to the different non-linear evolution and structures they form in galaxies: the fuzzy dark matter (FDM), the self-interacting fuzzy dark matter (SIFDM), and the DM superfluid. Each of these classes comprises many models, each presenting a similar phenomenology in galaxies. They also include some microscopic models like the axions and axion-like particles. To understand and describe this phenomenology in galaxies, we are going to review the phenomena of BEC and superfluidity that arise in condensed matter physics, and apply this knowledge to DM. We describe how ULDM can potentially reconcile the cold DM picture with the small-scale behaviour. These models present a rich phenomenology that is manifest in different astrophysical consequences. We review here the astrophysical and cosmological tests used to constrain those models, together with new and future observations that promise to test these models in different regimes. For the case of the FDM class, the mass where this model has an interesting phenomenology on small-scales $$ \sim 10^{-22}\, \mathrm {eV}$$ ∼ 10 - 22 eV , is strongly challenged by current observations. The parameter space for the other two classes remains weakly constrained. We finalize by showing some predictions that are a consequence of the wave nature of this component, like the creation of vortices and interference patterns, that could represent a smoking gun in the search of these rich and interesting alternative class of DM models.
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Guell, Kathleen, Emmanuel Pinteaux, and Gregory Bix. "Abstract 164: IL-1a Enhances Angiogenic Neurorepair After Experimental Ischemic Stroke." Stroke 46, suppl_1 (February 2015). http://dx.doi.org/10.1161/str.46.suppl_1.164.
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Stroke is a major cause of death and disability worldwide. Unfortunately, all clinical trials that have targeted the primary cerebral ischemia (CI) injury mechanisms of oxidative stress and excitotoxicity have failed. However, CI also induces a potent local inflammatory response that leads to damage in the ischemic penumbra but may also, less acutely, initiate and sustain post-stroke repair processes such as angiogenesis. We hypothesize that the pro-inflammatory cytokine IL-1α promotes angiogenesis after stroke via generation of pro-angiogenic perlecan laminin globular domain 3 (LG3) protein fragments from the brain extracellular matrix. This is based on our previous observations that LG3 is rapidly and persistently generated after CI in vivo, and that IL-1α causes cells of the neurovascular unit to generate LG3 in vitro . Importantly, the potential role of IL-1α in brain angiogenesis has not been previously studied. We now report that IL-1α activates primary brain endothelial cells (BECs) in vitro and significantly enhances several stages of BEC angiogenesis including proliferation and capillary tube-like structure morphogenesis. Furthermore, after experimental stroke (distal transient middle cerebral artery occlusion) in adult C57Bl6 mice, IL-1α levels are chronically (21 days) elevated (measured by qPCR and ELISA) suggesting that IL-1α is persists beyond the acute stroke phase to affect post-stroke angiogenic repair. Finally, IL-1α deficient mice have diminished post-stroke penumbral angiogenesis. Our results collectively suggest that inflammatory mediators such as IL-1α, in addition to their acute deleterious effects, may play an important and previously unrecognized role in post-stroke neurorepair that could be therapeutically exploited.
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Abdullahi Ibrahim, Aisha. "RESTRUCTURING NATIONAL LANGUAGE POLICY IN NIGERIA: A NEW DIRECTION TO EDUCATIONAL DEVELOPMENT." European Journal of Foreign Language Teaching 5, no. 6 (January 20, 2022). http://dx.doi.org/10.46827/ejfl.v5i6.4127.
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The emergence of the Universal Basic Education (UBE) Programme in Nigeria was in September 1999. The Programme was amended in 2008 by the Federal Government of Nigeria, through the Nigerian Educational Research and Development Council (NERDC). This yielded a great landmark for introducing and developing the 9-Year Basic Education Curriculum (BEC) which was aimed enabling every Nigerian citizen access to equivalent education comprehensively and coeducationally. Similarly, Nigeria's national language policy which focused on the official structure of the English language as an official medium of instruction from primary four to subsequent levels of education, while the mother tongue or the language of the immediate community to be the medium of instruction at pre-primary and early primary levels has left a wide gap which may serve as one of the factors or reasons that may affect the communicative competence of pupils or learners in handling English as a subject or medium of instruction. Especially, considering the designed objectives of inculcating in the school childrens’ permanent literacy, numeracy and the ability to communicate effectively which lays the concrete educational foundation of pupils in terms of language development. The common criticisms or observations that this paper may raise on the issue of language policy and that of UBE is lack of a well-articulated transition from the mother tongue to English, or lack of proper implementation of the policy, as language cannot be properly taught using another language. Therefore, the paper draws the attention of policymakers and curriculum designers in revising and restructuring the language policy in order to ascertain the objectives designed by UBE and the educational policy in general.<p> </p><p><strong> Article visualizations:</strong></p><p><img src="/-counters-/edu_01/0940/a.php" alt="Hit counter" /></p>