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Renbi, Abdelghani, Arash Risseh, Rikard Qvarnström y Jerker Delsing. "Impact of etch factor on characteristic impedance, crosstalk and board density". International Symposium on Microelectronics 2012, n.º 1 (1 de enero de 2012): 000312–17. http://dx.doi.org/10.4071/isom-2012-tp24.
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Signal integrity becomes more important when the length of the Printed Wiring Board (PWB) traces surpasses where λ denotes the wavelength. For fast digital communication purpose and low energy consumption in CMOS technology, faster rise time of the clock which means higher harmonic frequency, has always been preferable. In this case, the importance of considering signal integrity gets a higher priority as issues such reections and crosstalk between adjacent traces cannot be omitted, especially in dense High Density Interconnect (HDI) boards. Several factors control the effect of reections and the crosstalk such as the shape and dimension of the traces, the isolator characteristics which is inserted between the trace and the ground plane, the nearness and the geometry of the nearby conductors. In other words, these factors control the characteristic impedance of the traces and the mutual inductances and capacitances between the adjacent traces. Although these factors have been taken into account during the design phase for good signal integrity, the manufacturing process, which differs from vendor to vendor, has a great impact on the above factors. PWB manufacturing process may result in many different variations, which involve the dielectric constant, the thickness of the insulator, the trace width and the copper foil thickness. In addition to these variations, the etching quality that falls mainly in three different categories of trapezoidal trace form. In this paper we present the effect of three different etching shapes on the characteristic impedance. Moreover, it is concluded that one could gain space which can be used for shrinking the electronics and/or saving the raw material when trading the characteristic impedance error for space. Similar method is followed to investigate the crosstalk reduction between two adjacent microstriplines when tolerating the error in the characteristic impedance. This procedure can only be applied when a 90° etch angle process is feasible.
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Wang, Jiang Feng, Shuo Nie, Xue Dong Yan y Wang Xiang. "Multi-Scenarios Vehicle Traces Modeling in Co-Simulation of Vehicular Ad-Hoc Networks". Applied Mechanics and Materials 178-181 (mayo de 2012): 2694–98. http://dx.doi.org/10.4028/www.scientific.net/amm.178-181.2694.
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Vehicular ad hoc networks (VANETs) form when vehicles are equipped with devices capable of short-range wireless communication. Realistic vehicle trace modeling for VANETs simulations is a challenging task, which requires the reliable characterization of vehicular mobility. In this study, three different vehicle scenarios are proposed to analyze the difference between vehicle traces in multi-scenarios: city road, expressway and highway. Common trace modeling tools and characters of the scenarios are explored. Furthermore, three experimental scenarios are established using VanetMobiSim to produce vehicle traces. The experimental results show that the trend of the average speed versus the number of vehicles is different, and the vehicular density distribution demonstrates the realism of vehicle trace under multi-scenarios.
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Ourabah, Amine y Allan Chatenay. "Unlocking ultra-high-density seismic for CCUS applications by combining nimble nodes and agile source technologies". Leading Edge 41, n.º 1 (enero de 2022): 27–33. http://dx.doi.org/10.1190/tle41010027.1.
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In the quest for denser, nimbler, and lower-cost seismic surveys, the industry is seeing a revolution in the miniaturization of seismic equipment, with autonomous nodes approaching the size of a geophone and sources becoming portable by crews on foot. This has created a paradigm shift in the way seismic is acquired in difficult terrains, making zero-environmental-footprint surveys a reality while reducing cost and health, safety, and environmental risk. The simplification of survey operation and the new entry price of seismic surveys unlocked by these technologies are already benefiting industries beyond oil and gas exploration. High trace density seismic has become accessible to industries playing a key role in the net-zero era, such as geothermal and carbon capture, utilization, and storage (CCUS), to which a good understanding of the subsurface geology is crucial to their success. We describe these benefits as observed during an ultra-high-density seismic survey acquired in June 2020 through a partnership between STRYDE, Explor, and Carbon Management Canada over the Containment and Monitoring Institute site. The smallest and lightest source and receiver equipment in the industry were used to achieve a trace density of 257 million traces/km2 over this test site dedicated to CCUS studies. We discuss the operational efficiency of the seismic acquisition, innovative techniques for data transfer and surveying, and preliminary results of the seismic data processing with a focus on the near-surface model and fast-track time migration.
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O'NEIL, GRETCHEN R., LYDIA S. TACKETT y MICHAEL B. MEYER. "THE ROLE OF SURFICIAL BIOTURBATION IN THE LATEST EDIACARAN: A QUANTITATIVE ANALYSIS OF TRACE FOSSIL INTENSITY IN THE TERMINAL EDIACARAN–LOWER CAMBRIAN OF CALIFORNIA". PALAIOS 37, n.º 12 (29 de diciembre de 2022): 703–17. http://dx.doi.org/10.2110/palo.2021.050.
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ABSTRACT Bioturbating activities have played a vital role in shaping the marine ecosystem throughout metazoan history, influencing the abundance and preservation potential of body fossil-producing taxa and driving major environmental and geochemical changes. The earliest trace making behaviors arose during the late Ediacaran Period (∼ 560–541 Ma), disrupting the substrate previously occupied by dominantly sessile organisms. Simple dwelling and grazing behaviors exploited the organic-rich matgrounds, expanding into the underutilized microbial mat ecosystem. In the western United States, trace assemblages from Ediacaran–Cambrian boundary-spanning deposits document a thriving trace-maker ecosystem. One boundary-spanning deposit in this region, the lower member of the Wood Canyon Formation, crops out along the California-Nevada boundary and contains both trace and body fossil assemblages. The Chicago Pass section of the lower Wood Canyon Formation contains a suite of dominantly simple Ediacaran traces, which become commonplace in the upper part of the stratigraphic section, documenting the onset of prevalent trace-making behaviors in this region. While traces have been previously described from this locality, the addition of the complex trace Lamonte trevallis and quantification of trace fossil density of simple Ediacaran traces provides a more comprehensive ichnological view of the Chicago Pass section. Although Chicago Pass does not yield abundant tubicolous body fossils, as are found elsewhere in the region, the low diversity ichnoassemblages document both burgeoning surficial trace making groups and mat-targeted mining in the latest Ediacaran. The behaviors present at Chicago Pass are similar to those of the Dengying Formation in South China, and highlight the need for petrographic-based trace fossil studies. Additionally, studies of Nama Group trace fossils of the same age from Namibia report higher diversity and complexity in trace-making activities than what has been observed at Chicago Pass, but with similar, low Ediacara biota body fossil diversity. If Ediacara biota diversity is anticorrelated with trace-making behaviors, Chicago Pass represents a low-complexity end-member of the same phenomenon observed in Namibia. The effect of surface sediment disruption on the sessile Ediacaran communities may have been decoupled from complexity of the traces, more so influenced by the presence of general trace-making behaviors in aggregate, including simple traces.
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Wooden, Mark. "Union Amalgamations and the Decline in Union Density". Journal of Industrial Relations 41, n.º 1 (marzo de 1999): 35–52. http://dx.doi.org/10.1177/002218569904100102.
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Confronted by a marked decline in trade union density, the union movement in Australia bas responded by promoting the restructuring and amolgamation of trade unions. As a result, the number of active trade unions in Australia has fallen markedly since 1990. Despite tbis, the decline in trade union density accelerated during the 1990s, leading some analysts to suggest that the union amalgamation process may actually have been counterproductive in terms of overall trade union membership. This article tests this hypothesis using panel data collected as part of the Australian Workplace Industrial Relations Survey. A regression model of changes in union density in the period 1989/90 to 1995 is developed and estimated. The results indicate that while declining union numbers have been associated with the decline in union density, none of the blame for the fall can be traced to the amalgamation process.
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Chamoux, Marie-Noëlle. "¿Hacia el indio nuevo? De lo global a lo local y a la inversa en pueblos nahuas del norte de Puebla". Revista Trace, n.º 50 (10 de julio de 2018): 34. http://dx.doi.org/10.22134/trace.50.2006.423.
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La vida cotidiana en las comunidades indígenas ha sufrido muchos cambios desde los años cuarenta del siglo XX. El espacio, tal como los indígenas se lo apropian prácticamente, revela estos cambios. Se usa los conceptos de “mundo rural”, dominado por lo agropecuario, y de “lugares”, espacios con alta densidad de relaciones sociales. Se examina el caso de los nahuas del norte de Puebla (municipio de Huauchinango), señalando el ocaso del etos rural y la dominación ya instalada de valores urbanos. Se constata sin embargo, la permanencia de fuertes solidaridades familiares y el arraigo al pueblo. Pero en cambio se observa la pérdida de sentido del territorio del pueblo, tanto en su uso económico como en su apropiación simbólica y ritual. Casa, pueblo, comarca y “mundo exterior” son los espacios considerados para evaluar los cambios sufridos e imaginar un porvenir ya fuertemente amarrado a la modernidad.Abstract: Daily life in indigenous communities has suffered many changes since the nineteen forties. Space reveals these changes through the manner in which indigenous populations appropriate it. Concepts are employed such as “the rural world”, dominated by agricultural and livestock activity and “places”, spaces containing a high density of social relations. We examine the case of Nahuas in the north of Puebla (municipality of Huauchinango), pointing out a decline in rural ethos and the establishing of a domination of urban values. Nevertheless we verify the permanence of strong family solidarities and attachment to the village. On the other hand we observe the loss of a sense of territory, both in terms of economic use as in symbolic and ritual appropriation. House, village, region and “outside world” are the space taken into consideration to evaluate the changes suffered and to imagine a future firmly tied to modernity.Résumé : La vie quotidienne dans les communautés indigènes a subi de nombreux changements depuis les années quarante du XXe siècle. L’espace, tel que les Indiens se l’approprient dans la pratique, en porte la trace. On utilise les concepts de “milieu rural”, dominé par l’agriculture, et de “lieux”, espaces de haute densité de relations sociales. On examine le cas des Nahuas du nord de Puebla (municipe de Huauchinango), en signalant le déclin d’un etos rural et la domination déjà installée des valeurs urbaines. On constate cependant la permanence de fortes solidarités familiales et l’attachement au village. En revanche on observe la perte de sens du territoire, tant dans ses usages économiques que dans son appropriation symbolique et rituelle. L’habitat, le village, la contrée et le “monde extérieur” sont considérés pour évaluer les changements subis et imaginer un avenir déjà fortement amarré à la modernité.
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Jiang, Chunhua, Cong Zhao, Xuhui Zhang, Tongxin Liu, Ziwei Chen, Guobin Yang y Zhengyu Zhao. "A Method for Automatic Inversion of Oblique Ionograms". Remote Sensing 14, n.º 7 (30 de marzo de 2022): 1671. http://dx.doi.org/10.3390/rs14071671.
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In this study, a method is proposed to carry out automatic inversion of oblique ionograms to extract the parameters and electron density profile of the ionosphere. The proposed method adopts the quasi-parabolic segments (QPS) model to represent the ionosphere. Firstly, numerous candidate electron density profiles and corresponding vertical traces were, respectively, calculated and synthesized by adjusting the parameters of the QPS model. Then, the candidate vertical traces were transformed to oblique traces by the secant theorem and Martyn’s equivalent path theorem. On the other hand, image processing technology and characteristics of oblique echoes were adopted to automatically scale the key parameters (the maximum observable frequency and minimum group path, etc.) from oblique ionograms. The synthesized oblique traces, whose parameters were close to autoscaled parameters, were selected as the candidate traces to produce a correlation with measured oblique ionograms. Lastly, the proposed algorithm searched the best-fit synthesized oblique trace by comparing the synthesized traces with oblique ionograms. To test its feasibility, oblique ionograms were automatically scaled by the proposed method and these autoscaled parameters were compared with manual scaling results. The preliminary results show that the accuracy of autoscaled maximum observable frequency and minimum group path of the ordinary trace of the F2 layer is, respectively, about 91.98% and 86.41%, which might be accurate enough for space weather specifications. It inspires us to improve the proposed method in future studies.
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Wei Huaikun, 韦怀坤, 宦述虎 Huan Shuhu, 刘颖 Liu Ying, 陈火耀 Chen Huoyao, 邱克强 Qiu Keqiang, 刘正坤 Liu Zhengkun y 洪义麟 Hong Yilin. "用长程面形仪对变线距光栅的线密度进行拼接测量". Acta Optica Sinica 43, n.º 3 (2023): 0312007. http://dx.doi.org/10.3788/aos221409.
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Scotto, Carlo. "Triple splitting and z-rays in polar ionograms". Antarctic Science 27, n.º 4 (29 de enero de 2015): 383–87. http://dx.doi.org/10.1017/s095410201400090x.
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AbstractThe theory of propagation in a direction almost parallel to the Earth’s magnetic field is reviewed, calculating the group refractive index of the ordinary ray in the presence of electron-neutral collisions. An electron density profile is estimated from the ordinary trace and is used to compute the z-ray trace. It is shown that this reconstruction can help to identify the rare cases of z-rays from among the numerous cases of duplicate ordinary traces, due to reflection from two different directions.
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Kakuwa, Yoshitaka y James D. Floyd. "Trace fossils in Ordovician radiolarian chert successions in the Southern Uplands, Scotland". Earth and Environmental Science Transactions of the Royal Society of Edinburgh 107, n.º 1 (marzo de 2016): 13–22. http://dx.doi.org/10.1017/s1755691017000044.
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ABSTRACTRadiolarian chert and associated siliceous claystone in the Southern Uplands of Scotland are examined, in order to study the Great Ordovician Biodiversification Event of benthic animals on the pelagic ocean bottom. Trace fossils which are uncommon, but convincing, are found in the grey chert and siliceous claystone of Gripps Cleuch. These observations constitute firm evidence that large benthic animals which could leave visible trace fossils had colonised the Iapetan Ocean by the late Middle Ordovician, confirming previous studies from Australia for Panthalassa, the other huge ocean. Red chert is, however, a poor recorder of trace fossils, probably because the highly oxidising environment breaks down organic matter, both inhibiting high-density activity of large benthic animals and removing clear traces of benthic animal life.
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Archer, John, Milos Delic y Frank Nicholson. "Innovative high trace density design with broadband seismic data acquisition in the Cooper–Eromanga Basins, Australia". APPEA Journal 58, n.º 2 (2018): 773. http://dx.doi.org/10.1071/aj17111.
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Through a combination of innovative survey design, new technology and the introduction of novel operational techniques, the trace density of a 3D seismic survey in the Cooper Basin was increased from a baseline of 140 000 to 1 600 000 traces km–2, the bandwidth of the data was extended from four to six octaves, and the dataset was acquired in substantially the same time-frame and for the same cost as the baseline survey.
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Radzki, Wiktor. "Contractions of Product Density Operators of Systems of Identical Fermions and Bosons". International Journal of Mathematics and Mathematical Sciences 2010 (2010): 1–26. http://dx.doi.org/10.1155/2010/890523.
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Recurrence and explicit formulae for contractions (partial traces) of antisymmetric and symmetric products of identical trace class operators are derived. Contractions of product density operators of systems of identical fermions and bosons are proved to be asymptotically equivalent to, respectively, antisymmetric and symmetric products of density operators of a single particle, multiplied by a normalization integer. The asymptotic equivalence relation is defined in terms of the thermodynamic limit of expectation values of observables in the states represented by given density operators. For some weaker relation of asymptotic equivalence, concerning the thermodynamic limit of expectation values of product observables, normalized antisymmetric and symmetric products of density operators of a single particle are shown to be equivalent to tensor products of density operators of a single particle.
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Wang, Zhikai, Satish C. Singh y Mark Noble. "True-amplitude versus trace-normalized full waveform inversion". Geophysical Journal International 220, n.º 2 (26 de noviembre de 2019): 1421–35. http://dx.doi.org/10.1093/gji/ggz532.
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SUMMARY Full waveform inversion (FWI) is a powerful method to estimate high-resolution physical parameters of the subsurface by iteratively minimizing the misfit between the observed and synthetic seismic data. Standard FWI algorithms measure seismic misfit between amplitude-preserved seismic data (true-amplitude FWI). However, in order to mitigate the variations in sources and recording systems acquired on complex geological structures and the physics that cannot be modelled using an approximation of the seismic wave equation, the observed and synthetic seismic data are normalized trace-by-trace and then used to perform FWI. Trace-by-trace normalization removes the amplitude effects related to offset variations and only keeps the phase information. Furthermore, trace-by-trace normalization changes the true amplitude difference because of different normalization factors used for the corresponding synthetic and observed traces. In this paper, we study the performance of true-amplitude FWI and trace-normalized-residual-based FWI in the time domain. The misfit function of trace-normalized-residual-based FWI is defined such that the adjoint source used in gradient calculation is the trace-normalized seismic residual. We compare the two inversion schemes with synthetic seismic data simulated on laterally invariant models and the more complex 2-D Marmousi model. In order to simulate realistic scenarios, we perform the elastic FWI ignoring attenuation to noisy seismic data and to the synthetic data modelled using a viscoelastic modelling scheme. Comparisons of seismic data and adjoint sources show that trace-by-trace normalization increases the magnitude of seismic data at far offsets, which are usually more cycle-skipped than those at near offsets. The inverted results on linear-gradient models demonstrate that trace-by-trace normalization increases the non-linearity of FWI, so an initial model with sufficient accuracy is required to guarantee the convergence to the global minimum. The inverted results and the final seismic residuals computed using seismic data without trace-by-trace normalization demonstrate that true-amplitude FWI provides inverted models with higher accuracy than trace-normalized-residual-based FWI, even when the unknown density is updated using density–velocity relationship in inversion or in the presence of noise and complex physics, such as attenuation.
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Teague, Richard, Jaehan Bae, Sean M. Andrews, Myriam Benisty, Edwin A. Bergin, Stefano Facchini, Jane Huang, Cristiano Longarini y David Wilner. "Mapping the Complex Kinematic Substructure in the TW Hya Disk". Astrophysical Journal 936, n.º 2 (1 de septiembre de 2022): 163. http://dx.doi.org/10.3847/1538-4357/ac88ca.
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Abstract We present ALMA observations of CO J = 2 − 1 and CS J = 5 − 4 emission from the disk around TW Hydrae. Both molecules trace a predominantly Keplerian velocity structure, although a slowing of the rotation velocity is detected at the outer edge of the disk beyond ≈140 au in CO emission. This was attributed to the enhanced pressure support from the gas density taper near the outer edge of the disk. Subtraction of an azimuthally symmetric background velocity structure reveals localized deviations in the gas kinematics traced by each of the molecules. Both CO and CS exhibit a “Doppler flip” feature, centered nearly along the minor axis of the disk (PA ∼ 60°) at a radius of 1.″35, coinciding with the large gap observed in scattered light and mm continuum. In addition, the CO emission, both through changes in intensity and its kinematics, traces a tightly wound spiral, previously seen with higher-frequency CO J = 3 − 2 observations. Through comparison with linear models of the spiral wakes generated by embedded planets, we interpret these features in the context of interactions with a Saturn-mass planet within the gap at a position angle of PA = 60°, consistent with the theoretical predictions of Mentiplay et al. The lack of a corresponding spiral in the CS emission is attributed to the strong vertical dependence on the buoyancy spirals, which are believed to only grow in the atmospheric of the disk, rather than those traced by CS emission.
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Cabrera, M. A., M. Pezzopane, E. Zuccheretti y R. G. Ezquer. "Satellite traces, range spread-F occurrence, and gravity wave propagation at the southern anomaly crest". Annales Geophysicae 28, n.º 5 (18 de mayo de 2010): 1133–40. http://dx.doi.org/10.5194/angeo-28-1133-2010.
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Abstract. Range spread-F (RSF) and occurrence of "satellite" traces prior to RSF onset were studied at the southern peak of the ionospheric equatorial anomaly (EA). Ionograms recorded in September 2007 at the new ionospheric station of Tucumán, Argentina (26.9° S, 294.6° E, dip latitude 15.5° S), by the Advanced Ionospheric Sounder (AIS) developed at the Istituto Nazionale di Geofisica e Vulcanologia (INGV), were considered. Satellite traces (STs) are confirmed to be a necessary precursor to the appearance of an RSF trace on the ionograms. Moreover, an analysis of isoheight contours of electron density seems to suggest a relationship between RSF occurrence and gravity wave (GW) propagation.
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Dong, Fuyu, Pengjie Zhang, Le Zhang, Ji Yao, Zeyang Sun, Changbom Park y Xiaohu Yang. "Detection of a Cross-correlation between Cosmic Microwave Background Lensing and Low-density Points". Astrophysical Journal 923, n.º 2 (1 de diciembre de 2021): 153. http://dx.doi.org/10.3847/1538-4357/ac2d31.
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Abstract Low-density points (LDPs), obtained by removing high-density regions of observed galaxies, can trace the large-scale structures (LSSs) of the universe. In particular, it offers an intriguing opportunity to detect weak gravitational lensing from low-density regions. In this work, we investigate the tomographic cross-correlation between Planck cosmic microwave background (CMB) lensing maps and LDP-traced LSSs, where LDPs are constructed from the DR8 data release of the DESI legacy imaging survey, with about 106–107 galaxies. We find that, due to the large sky coverage (20,000 deg2) and large redshift depth (z ≤ 1.2), a significant detection (10σ–30σ) of the CMB lensing–LDP cross-correlation in all six redshift bins can be achieved, with a total significance of ∼53σ over ℓ ≤ 1024. Moreover, the measurements are in good agreement with a theoretical template constructed from our numerical simulation in the WMAP 9 yr ΛCDM cosmology. A scaling factor for the lensing amplitude A lens is constrained to A lens = 1 ± 0.12 for z < 0.2, A lens = 1.07 ± 0.07 for 0.2 < z < 0.4, and A lens = 1.07 ± 0.05 for 0.4 < z < 0.6, with the r-band absolute magnitude cut of −21.5 for LDP selection. A variety of tests have been performed to check the detection reliability against variations in LDP samples and galaxy magnitude cuts, masks, CMB lensing maps, multipole ℓ cuts, sky regions, and photo-z bias. We also perform a cross-correlation measurement between CMB lensing and galaxy number density, which is consistent with the CMB lensing–LDP cross-correlation. This work therefore further convincingly demonstrates that LDP is a competitive tracer of LSS.
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Liang, Shuang, Yun Zhu y Hao Li. "Evolutionary Optimization Based Set Joint Integrated Probabilistic Data Association Filter". Electronics 11, n.º 4 (15 de febrero de 2022): 582. http://dx.doi.org/10.3390/electronics11040582.
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The joint integrated probabilistic data association (JIPDA) algorithm is widely used for the automatic tracking of multiple targets, but it has the well-known problem of track coalescence. By optimizing the posterior density, the accuracy of the target state estimation can be improved. Motivated by this idea, we developed a novel evolutionary optimization based joint integrated probabilistic data association (EOJIPDA) filter to overcome the coalescence problem of the JIPDA filter. The trace for the covariance matrix of the posterior density is used as the objective function for the above optimization problem. It is shown that the accuracy of the target state estimation can be improved by reducing the trace. Evolutionary optimization was employed to minimize the trace and optimize the posterior density. More specifically, we enumerated all the possible permutations of the targets and assign a unique index to each permutation. The resulting indices were randomly assigned to all possible association hypothesis events. Each assignment indicated one possible gene in the evolutionary algorithm. This process was repeated several times to arrive at the initial population. An illustrative example shows that the EOJIPDA filter can effectively improve the accuracy of state estimation. Numerical studies are presented for two challenging multi-target tracking scenarios with clutter and missed detections. The experimental results demonstrate that the EOJIPDA filter provides better tracking accuracy than traditional coalescence-avoiding methods.
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Sheldrick, George M. "Experimental phasing withSHELXC/D/E: combining chain tracing with density modification". Acta Crystallographica Section D Biological Crystallography 66, n.º 4 (24 de marzo de 2010): 479–85. http://dx.doi.org/10.1107/s0907444909038360.
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The programsSHELXC, SHELXDandSHELXEare designed to provide simple, robust and efficient experimental phasing of macromolecules by the SAD, MAD, SIR, SIRAS and RIP methods and are particularly suitable for use in automated structure-solution pipelines. This paper gives a general account of experimental phasing using these programs and describes the extension of iterative density modification in SHELXEby the inclusion of automated protein main-chain tracing. This gives a good indication as to whether the structure has been solved and enables interpretable maps to be obtained from poorer starting phases. The autotracing algorithm starts with the location of possible seven-residue α-helices and common tripeptides. After extension of these fragments in both directions, various criteria are used to decide whether to accept or reject the resulting poly-Ala traces. Noncrystallographic symmetry (NCS) is applied to the traced fragments, not to the density. Further features are the use of a `no-go' map to prevent the traces from passing through heavy atoms or symmetry elements and a splicing technique to combine the best parts of traces (including those generated by NCS) that partly overlap.
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Bouvier, Guillaume, Benjamin Bardiaux, Riccardo Pellarin, Chiara Rapisarda y Michael Nilges. "Building Protein Atomic Models from Cryo-EM Density Maps and Residue Co-Evolution". Biomolecules 12, n.º 9 (13 de septiembre de 2022): 1290. http://dx.doi.org/10.3390/biom12091290.
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Electron cryo-microscopy (cryo-EM) has emerged as a powerful method by which to obtain three-dimensional (3D) structures of macromolecular complexes at atomic or near-atomic resolution. However, de novo building of atomic models from near-atomic resolution (3–5 Å) cryo-EM density maps is a challenging task, in particular because poorly resolved side-chain densities hamper sequence assignment by automatic procedures at a lower resolution. Furthermore, segmentation of EM density maps into individual subunits remains a difficult problem when the structure of the subunits is not known, or when significant conformational rearrangement occurs between the isolated and associated form of the subunits. To tackle these issues, we have developed a graph-based method to thread most of the C-α trace of the protein backbone into the EM density map. The EM density is described as a weighted graph such that the resulting minimum spanning tree encompasses the high-density regions of the map. A pruning algorithm cleans the tree and finds the most probable positions of the C-α atoms, by using side-chain density when available, as a collection of C-α trace fragments. By complementing experimental EM maps with contact predictions from sequence co-evolutionary information, we demonstrate that this approach can correctly segment EM maps into individual subunits and assign amino acid sequences to backbone traces to generate atomic models.
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Yerimbetova, Dana S., Artem L. Kozlovskiy, Umitali N. Tuichiyev y Kassym S. Zhumadilov. "Study of the Sensitivity Limit of Detection of α-Particles by Polymer Film Detectors LR-115 Type 2 Using X-ray Diffraction and UV-Vis Spectroscopic Methods". Polymers 15, n.º 11 (29 de mayo de 2023): 2500. http://dx.doi.org/10.3390/polym15112500.
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This work is devoted to the applicability assessment of optical spectroscopy and X-ray diffraction methods to establish the lower detection limit for the density of latent tracks from α-particles in polymer nuclear-track detectors, in the case of simulation of the formation of radon decay daughter products using Am-241 sources. During the studies, the detection limit for the density of latent tracks—traces of the interaction of α-particles with the molecular structure of film detectors—was established using optical UV spectroscopy (104 track/cm2) and X-ray diffraction (104 track/cm2). At the same time, analysis of the connection between structural and optical changes in polymer films indicates that a growth in the density of latent tracks above 106–107 results into the formation of an anisotropic change in the electron density associated with distortions in the molecular structure of the polymer. An analysis of the parameters of diffraction reflections (the position and width of the diffraction maximum) showed that in the range of latent track densities of 104–108 track/cm2, the main changes in these values are associated with deformation distortions and stresses caused by ionization processes during the interaction of incident particles with the molecular structure of the polymer. The increase in optical density, in turn, is caused by the accumulation of structurally changed regions (latent tracks) in the polymer as the irradiation density increases. A general analysis of the obtained data showed good agreement between the optical and structural characteristics of the films depending on the irradiation density.
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Esraa, Sh y I. Ahmed. "The Etching Effect Methods in Registration Properties on CR-39 Nuclear Track Detector". IOP Conference Series: Earth and Environmental Science 1325, n.º 1 (1 de abril de 2024): 012028. http://dx.doi.org/10.1088/1755-1315/1325/1/012028.
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Abstract In this work, we use three different etching techniques—water bath, microwaves, and hotplate stirrer devices—in an effort to confirm the optimal etching time and conditions for tracks in the CR-39 solid-state nuclear track detector following irradiation to an alpha particle source (241Am). The research shows that the water bath’s maximum track density is 57596 tracks/cm2, appearing at 90 and 150 minutes. On the other hand, the hotplate stirrer’s maximum track density is 28050 tracks/cm2, appearing at 90 and 150 minutes. The microwave is the best etching method since it generated the tracks (65076 tracks/cm2) in a relatively short amount of time (10 min). The computation of the etching parameters, which are the bulk etch rates (VB), track etch rate (VT) and track etch ratio (V), was investigate in the etching properties. The time for the appearance of all traces of the microwave device is at a time of 10 minutes, followed by a hotplate stirrer at a time of 90 minutes, then a water bath at a time of 120 minutes.
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Rojas, Alexis, Gregory P. Dietl, Michał Kowalewski, Roger W. Portell, Austin Hendy y Jason K. Blackburn. "Spatial point pattern analysis of traces (SPPAT): An approach for visualizing and quantifying site-selectivity patterns of drilling predators". Paleobiology 46, n.º 2 (mayo de 2020): 259–71. http://dx.doi.org/10.1017/pab.2020.15.
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AbstractSite-selectivity analysis of drilling predation traces may provide useful behavioral information concerning a predator interacting with its prey. However, traditional approaches exclude some spatial information (i.e., oversimplified trace position) and are dependent on the scale of analysis (e.g., arbitrary grid system used to divide the prey skeleton into sectors). Here we introduce the spatial point pattern analysis of traces (SPPAT), an approach for visualizing and quantifying the distribution of traces on shelled invertebrate prey, which includes improved collection of spatial information inherent to drillhole location (morphometric-based estimation), improved visualization of spatial trends (kernel density and hotspot mapping), and distance-based statistics for hypothesis testing (K-, L-, and pair correlation functions). We illustrate the SPPAT approach through case studies of fossil samples, modern beach-collected samples, and laboratory feeding trials of naticid gastropod predation on bivalve prey. Overall results show that kernel density and hotspot maps enable visualization of subtle variations in regions of the shell with higher density of predation traces, which can be combined with the maximum clustering distance metric to generate hypotheses on predatory behavior and anti-predatory responses of prey across time and geographic space. Distance-based statistics also capture the major features in the distribution of traces across the prey skeleton, including aggregated and segregated clusters, likely associated with different combinations of two modes of drilling predation, edge and wall drilling. The SPPAT approach is transferable to other paleoecologic and taphonomic data such as encrustation and bioerosion, allowing for standardized investigation of a wide range of biotic interactions.
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Murillo, N. M., E. F. van Dishoeck, J. J. Tobin, J. C. Mottram y A. Karska. "Role of environment and gas temperature in the formation of multiple protostellar systems: molecular tracers". Astronomy & Astrophysics 620 (23 de noviembre de 2018): A30. http://dx.doi.org/10.1051/0004-6361/201832954.
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Context. Simulations suggest that gas heating due to radiative feedback is a key factor in whether or not multiple protostellar systems will form. Chemistry is a good tracer of the physical structure of a protostellar system, since it depends on the temperature structure. Aims. We aim to study the relationship between envelope gas temperature and protostellar multiplicity. Methods. Single dish observations of various molecules that trace the cold, warm, and UV-irradiated gas were used to probe the temperature structure of multiple and single protostellar systems on 7000 AU scales. Results. Single, close binary, and wide multiples present similar current envelope gas temperatures, as estimated from H2CO and DCO+ line ratios. The temperature of the outflow cavity, traced by c-C3H2, on the other hand, shows a relation with bolometric luminosity and an anticorrelation with envelope mass. Although the envelope gas temperatures are similar for all objects surveyed, wide multiples tend to exhibit a more massive reservoir of cold gas compared to close binary and single protostars. Conclusions. Although the sample of protostellar systems is small, the results suggest that gas temperature may not have a strong impact on fragmentation. We propose that mass, and density, may instead be key factors in fragmentation.
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Friedland, Shmuel, Jingtong Ge y Lihong Zhi. "Quantum Strassen’s theorem". Infinite Dimensional Analysis, Quantum Probability and Related Topics 23, n.º 03 (septiembre de 2020): 2050020. http://dx.doi.org/10.1142/s0219025720500204.
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Strassen’s theorem circa 1965 gives necessary and sufficient conditions on the existence of a probability measure on two product spaces with given support and two marginals. In the case where each product space is finite, Strassen’s theorem is reduced to a linear programming problem which can be solved using flow theory. A density matrix of bipartite quantum system is a quantum analog of a probability matrix on two finite product spaces. Partial traces of the density matrix are analogs of marginals. The support of the density matrix is its range. The analog of Strassen’s theorem in this case can be stated and solved using semidefinite programming. The aim of this paper is to give analogs of Strassen’s theorem to density trace class operators on a product of two separable Hilbert spaces, where at least one of the Hilbert spaces is infinite-dimensional.
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Mángano, M. Gabriela, Christopher David Hawkes y Jean-Bernard Caron. "Trace fossils associated with Burgess Shale non-biomineralized carapaces: bringing taphonomic and ecological controls into focus". Royal Society Open Science 6, n.º 1 (enero de 2019): 172074. http://dx.doi.org/10.1098/rsos.172074.
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The association of trace fossils and non-biomineralized carapaces has been reported from Cambrian Lagerstätten worldwide, but the abundance, ichnodiversity, taphonomy and ecological significance of such associations have yet to be fully investigated. Two main end-member hypotheses are explored based on the study of a relatively wide variety of trace fossils preserved associated to Tuzoia carapaces from the middle Cambrian Burgess Shale in British Columbia. In the ecological Tuzoia garden hypothesis, the bacterially enriched surface of carapaces provides opportunities for intricate ecologic interactions among trophic levels. In the taphonomic shielding hypothesis, the trace fossil–carapace association results from preferential preservation of traces as controlled by compaction independent of any association in life. In an attempt to better understand the role of the carapace as a medium for preservation of trace fossils and to evaluate the effects of mechanical stress related to burial, a numerical model was developed. Results indicate that the carapace can shield underlying sediment from mechanical stress for a finite time, differentially protecting trace fossils during the initial phase of burial and compaction. However, this taphonomic model alone fails to fully explain relatively high-density assemblages displaying a diversity of structures spatially confined within the perimeter of carapaces or branching patterns recording re-visitation.
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Carpenter, Burton, Betty Yeung y Yuan Yuan. "Effects of Copper Pattern Density and Orientation on the Modulus of BGA Substrates". International Symposium on Microelectronics 2013, n.º 1 (1 de enero de 2013): 000486–91. http://dx.doi.org/10.4071/isom-2013-wa31.
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Substrate material properties directly impact package mechanical performance. Estimation of substrate mechanical properties based on each component layer provides maximum flexibility and better accuracy. The component materials of a BGA substrate are the fiberglass-reinforced epoxy layers, copper and soldermask. Even when the material properties (modulus and CTE) of each component are known, the behavior of the final substrate is not easily determined because factors such as copper density and pattern have significant effects. For example, the copper pattern may be oriented such that conductor traces run in one direction for a considerable length. The modulus in the direction parallel to the traces will be different from the modulus in the direction perpendicular to the traces. Package mechanical simulations typically do not mesh the details of the copper patterns, but rather average within each layer, thus neglecting the orientation effects. Therefore FEM (Finite Element Model) simulations may yield inaccurate stress and warpage results. This study utilized a test vehicle (TV) to study the copper pattern density and orientation effect on substrate modulus. Each TV sample was a two-metal-layer copper-clad laminate designed with one of eight simple geometric patterns. One set of patterns had Cu traces running parallel in one direction, with varied metal densities of 0%, 25%, 50%, 75% and 100% respectively. Measurements were made both parallel and perpendicular to the trace orientation. Also studied were a pattern of holes (continuous metal plane with unconnected holes) and a dot pattern (unconnected circular metal pads). Substrate flexural modulus measurements were made using two types of instruments: DMA and Instron. Data was collected from −65 to 260°C. FEM simulations which meshed the details of copper patterns were used to calculate the overall substrate modulus. These correlated better with the empirical data than simulations utilizing traditional layer averaging. The copper pattern had significant effects; the substrate modulus was always much lower in the direction perpendicular to the traces than the modulus in the direction parallel to the traces. The amount varied depending on temperature, but could be as high as 35%. When measured parallel to the copper traces, the substrate modulus was observed to increase with copper pattern density as predicted by theoretical mixture rules. However, the substrate modulus in the direction perpendicular to the traces was not easily predicted theoretically. Therefore, more sophisticated averaging techniques and simulations are needed.
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Tang, X. D., C. Henkel, F. Wyrowski, A. Giannetti, K. M. Menten, T. Csengeri, S. Leurini et al. "ATLASGAL-selected massive clumps in the inner Galaxy". Astronomy & Astrophysics 611 (marzo de 2018): A6. http://dx.doi.org/10.1051/0004-6361/201732168.
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Context. Formaldehyde (H2CO) is a reliable tracer to accurately measure the physical parameters of dense gas in star-forming regions. Aim. We aim to determine directly the kinetic temperature and spatial density with formaldehyde for the ~100 brightest ATLASGAL-selected clumps (the TOP100 sample) at 870 μm representing various evolutionary stages of high-mass star formation. Methods. Ten transitions (J = 3–2 and 4–3) of ortho- and para-H2CO near 211, 218, 225, and 291 GHz were observed with the Atacama Pathfinder EXperiment (APEX) 12 m telescope. Results. Using non-LTE models with RADEX, we derived the gas kinetic temperature and spatial density with the measured para-H2CO 321–220/303–202, 422–321/404–303, and 404–303/303–202 ratios. The gas kinetic temperatures derived from the para-H2CO 321–220/303–202 and 422–321/404–303 line ratios are high, ranging from 43 to >300 K with an unweighted average of 91 ± 4 K. Deduced Tkin values from the J = 3–2 and 4–3 transitions are similar. Spatial densities of the gas derived from the para-H2CO 404–303/303–202 line ratios yield 0.6–8.3 × 106 cm−3 with an unweighted average of 1.5 (±0.1) × 106 cm−3. A comparison of kinetic temperatures derived from para-H2CO, NH3, and dust emission indicates that para-H2CO traces a distinctly higher temperature than the NH3 (2, 2)/(1, 1) transitions and the dust, tracing heated gas more directly associated with the star formation process. The H2CO line widths are found to be correlated with bolometric luminosity and increase with the evolutionary stage of the clumps, which suggests that higher luminosities tend to be associated with a more turbulent molecular medium. It seems that the spatial densities measured with H2CO do not vary significantly with the evolutionary stage of the clumps. However, averaged gas kinetic temperatures derived from H2CO increase with time through the evolution of the clumps. The high temperature of the gas traced by H2CO may be mainly caused by radiation from embedded young massive stars and the interaction of outflows with the ambient medium. For Lbol/Mclump ≳ 10 L⊙/M⊙, we find a rough correlation between gas kinetic temperature and this ratio, which is indicative of the evolutionary stage of the individual clumps. The strong relationship between H2CO line luminosities and clump masses is apparently linear during the late evolutionary stages of the clumps, indicating that LH_2CO does reliably trace the mass of warm dense molecular gas. In our massive clumps H2CO line luminosities are approximately linearly correlated with bolometric luminosities over about four orders of magnitude in Lbol, which suggests that the mass of dense molecular gas traced by the H2CO line luminosity is well correlated with star formation.
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Ming, Ma, Hong Jie Li y He Lei. "3D Fracture Network and Block Analysis of the South End-Slope of Antaibao Coal Mine". Applied Mechanics and Materials 353-356 (agosto de 2013): 1165–70. http://dx.doi.org/10.4028/www.scientific.net/amm.353-356.1165.
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Based on actual measurement of fractures in south end-slope of Antaibao Coal Mine which adopted open-pit and underground mining, the fractures were grouped by directions, and for each group, distribution functions of direction, length and other geometric parameters and density on the observation window were calculated respectively. The statistic results showed that the fracture orientation followed Fisher distribution and the trace length followed lognormal distribution. According to the fractures number, the mean traces length and standard deviation, as well as one-dimensional density of each group, 3D fracture network was simulated with Monte-Carlo method. Then the block theoretical model was built according to the fracture model, and the block distribution of the south end-slope was analyzed and forecast.
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Rindsberg, Andrew K. y Jack C. Pashin. "Ichnology of a reworked strandplain complex: Mississippian Hartselle Sandstone of Alabama". Paleontological Society Special Publications 6 (1992): 247. http://dx.doi.org/10.1017/s2475262200008078.
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The Hartselle Sandstone of northern Alabama represents a mesotidal strandplain complex of Hombergian (middle Chesterian) age that was reworked by a transgressing sea. Transgressive reworking resulted in complex facies patterns that can best be deciphered by ichnology. Thickly bedded, unbioturbated beach to shoreface sandstone is widespread at the base of the formation. Wavy-bedded back-barrier to shelf sandstone and shale predominate in the middle and upper parts of the formation and contain distinctive assemblages of trace fossils, invertebrates, and plants.Barriers with a broad, gently sloping beach face and muddy coastal swamps typified the Hartselle strandplain which extended across northern Alabama. Barrier and coastal-swamp deposits lack trace fossils but locally contain an indigenous lycopod flora including stumps and Stigmaria root systems.Back-barrier tidal flats and lagoon deposits have trace-fossil assemblages dominated by bivalve traces that probably represent brackish environments. Marginal-marine sandstone contains chiefly monospecific assemblages and is reworked by bivalves and unknown organisms; Lockeia, Uchirites, and Rosselia are dominant at different sites. The Lockeia assemblage includes bedding surfaces with crowded bivalve resting traces. The abundance, density, and small size of monospecific burrows suggests estuarine conditions with high food supply and rapid larval colonization. The Uchirites assemblage is characterized by bivalve trails, representing probably brackish substrates with a high sedimentation rate.Shelf sandstone and shale include bivalve resting traces and trails (Lockeia ispp., Uchirites isp. aff. U. triangularis, Walcottia rugosa, and W. imbricata), asteroid and ophiuroid resting traces (Asteriacites stelliforme and Pentichnus pratti), trilobite resting traces and trackways (Rusophycus ispp. and Petalichnus isp.), and dwelling burrows, feeding burrows, trails, and trackways of unknown organisms (Chondrites-like burrows, Phycodes isp., Haplotichnus isp., Rosselia isp., Planolites montanus, Nereites missouriensis, Tasmanadia twelvetreesi, imbricate burrows, and wavelike burrows). Some shelf areas even supported diverse calcified faunas containing crinoids, fenestrate bryozoans, and articulate brachiopods.The Hartselle Sandstone is a facies mosaic that records indundation of an extensive strandplain complex and a distinctive stratigraphic succession of lithofacies and biofacies. Hartselle ichnofacies have unique aspects, but are similar to those of other marginal-marine Carboniferous strata in eastern North America. The paleoecologic complexity of the Hartselle Sandstone helps to establish the dynamic range of Carboniferous ecosystems, which have yet to be fully explored.
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Xie, Jinjin, Juan Li, Junzhi Wang, Shu Liu, Kai Yang, Donghui Quan, Siqi Zheng et al. "Imaging Molecular Outflow in Massive Star-forming Regions with HNCO Lines". Astrophysical Journal 949, n.º 2 (1 de junio de 2023): 89. http://dx.doi.org/10.3847/1538-4357/acc83f.
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Abstract Protostellar outflows are considered a signpost of star formation. These outflows can cause shocks in the molecular gas and are typically traced by the line wings of certain molecules. HNCO (4–3) has been regarded as a shock tracer because of the high abundance in shocked regions. Here we present the first imaging results of HNCO (4–3) line wings toward nine sources in a sample of 23 massive star-forming regions using the Instituto de Radioastronomía Milimétrica 30 m Telescope. We adopt the velocity range of the full width of HC3N (10–9) and H13CO+ (1–0) emissions as the central emission values, beyond which the emission from HNCO (4–3) is considered to be from line wings. The spatial distributions of the red and/or blue lobes of HNCO (4–3) emission nicely associate with those lobes of HCO+ (1–0) in most of the sources. High-intensity ratios of HNCO (4–3) to HCO+ (1–0) are obtained in the line wings. The derived column density ratios of HNCO to HCO+ are consistent with those previously observed toward massive star-forming regions. These results provide direct evidence that HNCO could trace outflow in massive star-forming regions. This work also implies that the formation of some HNCO molecules is related to shock, either on the grain surface or within the shocked gas.
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Gregorio, Glenn B., Dharmawansa Senadhira, H. Htut y Robin D. Graham. "Breeding for Trace Mineral Density in Rice". Food and Nutrition Bulletin 21, n.º 4 (enero de 2000): 382–86. http://dx.doi.org/10.1177/156482650002100407.
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Schlüter, Henrik, Florian Gayk, Heinz-Jürgen Schmidt, Andreas Honecker y Jürgen Schnack. "Accuracy of the typicality approach using Chebyshev polynomials". Zeitschrift für Naturforschung A 76, n.º 9 (21 de junio de 2021): 823–34. http://dx.doi.org/10.1515/zna-2021-0116.
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Abstract Trace estimators allow us to approximate thermodynamic equilibrium observables with astonishing accuracy. A prominent representative is the finite-temperature Lanczos method (FTLM) which relies on a Krylov space expansion of the exponential describing the Boltzmann weights. Here we report investigations of an alternative approach which employs Chebyshev polynomials. This method turns out to be also very accurate in general, but shows systematic inaccuracies at low temperatures that can be traced back to an improper behavior of the approximated density of states with and without smoothing kernel. Applications to archetypical quantum spin systems are discussed as examples.
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ARYANTA, DWI y BAYU AGUNG PRANATA. "Perancangan dan Analisis Redistribution Routing Protocol OSPF dan EIGRP". ELKOMIKA: Jurnal Teknik Energi Elektrik, Teknik Telekomunikasi, & Teknik Elektronika 2, n.º 2 (1 de julio de 2014): 85. http://dx.doi.org/10.26760/elkomika.v2i2.85.
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ABSTRAKOSPF (Open Shortest Path First) dan EIGRP (Enhanced Interior Gateway Routing Protocol) adalah dua routing protokol yang banyak digunakan dalam jaringan komputer. Perbedaan karakteristik antar routing protokol menimbulkan masalah dalam pengiriman paket data. Teknik redistribution adalah solusi untuk melakukan komunikasi antar routing protokol. Dengan menggunakan software Cisco Packet Tracer 5.3 pada penelitian ini dibuat simulasi OSPF dan EIGRP yang dihubungkan oleh teknik redistribution, kemudian dibandingkan kualitasnya dengan single routing protokol EIGRP dan OSPF. Parameter pengujian dalam penelitian ini adalah nilai time delay dan trace route. Nilai trace route berdasarkan perhitungan langsung cost dan metric dibandingkan dengan hasil simulasi. Hasilnya dapat dilakukan proses redistribution OSPF dan EIGRP. Nilai delay redistribution lebih baik 1% dibanding OSPF dan 2-3% di bawah EIGRP tergantung kepadatan traffic. Dalam perhitungan trace route redistribution dilakukan 2 perhitungan, yaitu cost untuk area OSPF dan metric pada area EIGRP. Pengambilan jalur utama dan alternatif pengiriman paket berdasarkan nilai cost dan metric yang terkecil, hal ini terbukti berdasarkan perhitungan dan simulasi.Kata kunci: OSPF, EIGRP, Redistribution, Delay, Cost, Metric.ABSTRACTOSPF (Open Shortest Path First) and EIGRP (Enhanced Interior Gateway Routing Protocol) are two routing protocols are widely used in computer networks. Differences between the characteristics of routing protocols pose a problem in the delivery of data packets. Redistribution technique is the solution for communication between routing protocols. By using the software Cisco Packet Tracer 5.3 in this study were made simulating OSPF and EIGRP redistribution linked by technique, then compared its quality with a single EIGRP and OSPF routing protocols. Testing parameters in this study is the value of the time delay and trace route. Value trace route based on direct calculation of cost and metric compared with the simulation results. The result can be OSPF and EIGRP redistribution process. Value delay redistribution 1% better than OSPF and EIGRP 2-3% under traffic density dependent. In calculating the trace route redistribution is done 2 calculations, the cost for OSPF area and the area of the EIGRP metric. Making primary and alternate paths based on the packet delivery rate and the cost of the smallest metric, it is proved by calculation and simulation.Keywords: OSPF, EIGRP, Redistribution, Delay, Cost, Metric.
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Li, Zhihao, Mike Schaff, Rolf Munson, Mark Jurisch, Ted Noonon, Shaoping Li y Yuming Zhou. "Adjacent track encroachment analysis at high track density". Journal of Applied Physics 93, n.º 10 (15 de mayo de 2003): 6456–58. http://dx.doi.org/10.1063/1.1557651.
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Habing, H. J. "AGB maser stars as tracers of stellar populations". International Astronomical Union Colloquium 193 (2004): 138–43. http://dx.doi.org/10.1017/s0252921100010496.
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AbstractMasers are known to occur in circumstellar envelopes of AGB stars that are long-period variables and have entered the TP-AGB phase. The maser radiation is intrinsically weak and detection limits prevent us from seeing maser stars much beyond the Galactic Center. Very deep searches have led to the detection of a handful of maser stars in the Large Magellanic Cloud. Some 1000 stellar masers are known. They trace a population of stars with main sequence masses between 1 and 6 M⊙ and ages between 2 and 8 Gyr, the same population that is traced by Cepheids. Their distribution in our Galaxy is the same as that of the red giants, and therefore the stars trace the galactic bar. An outstanding feature is a small disk of radius 150 pc around the galactic center. The disk is in rapid, solid body rotation and leads to a good measurement of the mass density within that distance for Sgr A.
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Ali Muttaqi Shah, Syed Hyder, François W. Primeau, Eric Deleersnijder y Arnold W. Heemink. "Tracing the Ventilation Pathways of the Deep North Pacific Ocean Using Lagrangian Particles and Eulerian Tracers". Journal of Physical Oceanography 47, n.º 6 (junio de 2017): 1261–80. http://dx.doi.org/10.1175/jpo-d-16-0098.1.
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AbstractLagrangian forward and backward models are introduced into a coarse-grid ocean global circulation model to trace the ventilation routes of the deep North Pacific Ocean. The random walk aspect in the Lagrangian model is dictated by a rotated isopycnal diffusivity tensor in the circulation model, and the effect of diffusion is explicitly resolved by means of stochastic terms in the Lagrangian model. The analogy between the probability distribution of a Lagrangian model with Green’s function of an Eulerian tracer transport equation is established. The estimated first- and last-passage time density of the deep North Pacific using both the Eulerian and the Lagrangian models ensured that the Lagrangian pathways and their ensemble statistics are consistent with the Eulerian tracer transport and its adjoint model. Moreover, the sample pathways of the ventilated mass fractions of the deep North Pacific particles to and from the ocean surface are studied.
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Saito, Y., D. Ito, N. Odaira, K. Kurita y H. Iikura. "Development of Tracer Particles for Thermal Hydraulic Experiment by Neutron Imaging". Journal of Physics: Conference Series 2605, n.º 1 (1 de septiembre de 2023): 012028. http://dx.doi.org/10.1088/1742-6596/2605/1/012028.
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Abstract To observe flow velocity distributions by Neutron Imaging, suitable tracers are necessary. Their performance is highly dependent on their density, visibility, and wettability (if applied to liquid metal). Gold cadmium tracers have been developed for the Pb-Bi two-phase flow, however the visibility have not been verified depending on the particle size and the measurement system. As the candidates of tracer particles, Ag, Cd, Au-Cd, and Ag-Cd have been tested by varying its compositions and their diameters. Results show enough visibility if the particles size is larger than 1mm. In addition, Cd tracer particles were applied to the fluidized bed, where the bed materials are metallic particle made of stainless steel, with 1mm diameter. The diameter of Cd trace is about 1.5 mm. From the neutron imaging, the visibility of the tracers is enough to measure the velocity distributions in the fluidized bed.
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Kondratenkov, I. A., M. L. Oparin y O. S. Oparina. "Estimation of the ecological density of some species of hunting animals according to winter route censuses". Povolzhskiy Journal of Ecology, n.º 1 (18 de junio de 2023): 58–76. http://dx.doi.org/10.35885/1684-7318-2023-1-58-76.
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This article is devoted to the study of the possibility of determining the ecological density of game animals according to winter route censuses. Determining the density of game animals is a prerequisite for determining their prey quotas. The most valuable parameter characterizing population estimation of specific species of game animals is ecological density. She calculated for the area actually inhabited by a particular animal species. The population density, calculated on the area suitable for the type of land, is widely used in the practice of domestic hunting. Territories with feeding and protective properties for this species are considered suitable sites. The materials of winter route counts confirm that the territories suitable for any animal species are not always completely populated by it, and the territories recognized as unsuitable are visited by these animals. Tracking activity of game animals is recorded both in areas that are considered suitable for the species, and in areas that are not typical for it. The territory of the animal during the day is the area lying inside the minimum convex contour drawn around the daily track of this animal. In this case, as the territory occupied by some animal, we can consider the territory obtained by combining all the minimum convex contours drawn around all daily traces left by this animal for a certain time. The union of the minimum convex contours drawn around all daily traces left by all animals of a given species during the period of accounting work can be considered as the territory inhabited by them at this time of the year. The crossing of a track by a route is a random event. Therefore, to determine the ecological density of a species according to the winter route censuses data, it is necessary to apply the probability theory.
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Balazs, P. y N. Teofanov. "Continuous frames in tensor product Hilbert spaces, localization operators and density operators". Journal of Physics A: Mathematical and Theoretical 55, n.º 14 (8 de marzo de 2022): 145201. http://dx.doi.org/10.1088/1751-8121/ac55eb.
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Abstract Continuous frames and tensor products are important topics in theoretical physics. This paper combines those concepts. We derive fundamental properties of continuous frames for tensor product of Hilbert spaces. This includes, for example, the consistency property, i.e. preservation of the frame property under the tensor product, and the description of the canonical dual tensors by those on the Hilbert space level. We show the full characterization of all dual systems for a given continuous frame, a result interesting by itself, and apply this to dual tensor frames. Furthermore, we discuss the existence on non-simple tensor product (dual) frames. Continuous frame multipliers and their Schatten class properties are considered in the context of tensor products. In particular, we give sufficient conditions for obtaining partial trace multipliers of the same form, which is illustrated with examples related to short-time Fourier transform and wavelet localization operators. As an application, we offer an interpretation of a class of tensor product continuous frame multipliers as density operators for bipartite quantum states, and show how their structure can be restricted to the corresponding partial traces.
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Vadas, S. L. y D. C. Fritts. "Reconstruction of the gravity wave field from convective plumes via ray tracing". Annales Geophysicae 27, n.º 1 (9 de enero de 2009): 147–77. http://dx.doi.org/10.5194/angeo-27-147-2009.
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Abstract. We implement gravity wave (GW) phases into our convective plume and anelastic ray trace models. This allows us to successfully reconstruct the GW velocity, temperature, and density perturbation amplitudes and phases in the Mesosphere-Lower-Thermosphere (MLT) via ray tracing (in real space) those GWs that are excited from a deep convective plume. We find that the ray trace solutions agree very well with the exact, isothermal, zero-wind, Fourier-Laplace solutions in the Boussinesq limit. This comparison also allows us to determine the normalization factor which converts the GW spectral amplitudes to real-space amplitudes in the ray trace model. This normalization factor can then be used for ray tracing GWs through varying temperature and wind profiles. We show that by adding GW reflection off the Earth's surface, the resulting GW spectrum has more power at larger vertical and horizontal wavelengths. We determine the form of the momentum flux and velocity spectra which allows for easy calculation of GW amplitudes in the MLT and thermosphere. Finally, we find that the reconstructed (ray traced) solution for a deep, convective plume with a duration much shorter than the buoyancy period does not equal the Fourier-Laplace Boussinesq solution; this is likely due to errors in the Boussinesq dispersion relation for very high frequency GWs.
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NAKAYAMA, YU. "SURPRISING TRACE ANOMALY FROM FREAKOLOGRAPHY". International Journal of Modern Physics: Conference Series 21 (enero de 2013): 63–76. http://dx.doi.org/10.1142/s2010194513009410.
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I will discuss how an unexpected form of trace anomaly can be obtained from holographic models with no simple string interpretation. In addition to the usual trace anomaly, Euler density and Weyl tensor squared, we pursue the possibility that it is given by Ricci scalar and Hirzebruch-Pontryagin density. It has a deep connection with scale but non-conformal field theories and their holographic dual. I would like to urge you to judge whether such holographic theories are consistent or pathological.
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Eskes, H. J. y K. F. Boersma. "Averaging kernels for DOAS total-column satellite retrievals". Atmospheric Chemistry and Physics Discussions 3, n.º 1 (18 de febrero de 2003): 895–910. http://dx.doi.org/10.5194/acpd-3-895-2003.
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Abstract. The Differential Optical Absorption Spectroscopy (DOAS) method is used extensively to retrieve total column amounts of trace gases based on UV-visible measurements of satellite spectrometers, such as ERS-2 GOME. In practice the sensitivity of the instrument to the tracer density is strongly height dependent, especially in the troposphere. The resulting tracer profile dependence may introduce large systematic errors in the retrieved columns that are difficult to quantify without proper additional information, as provided by the averaging kernel (AK). In this paper we generalise the AK concept to total column retrievals, and derive an explicit expression for the DOAS AK. It is shown that the additional AK information corrects for the a priori dependence of the retrieval. The availability of averaging kernel information as part of the total column retrieval product is essential for the interpretation of the observations, and for applications like chemical data assimilation and detailed satellite validation studies.
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McKay, Larry, Johnny Fredericia, Melissa Lenczewski, Jørn Morthorst y Knud Erik S. Klint. "Spatial Variability of Contaminant Transport in a Fractured Till, Avedøre Denmark". Hydrology Research 30, n.º 4-5 (1 de agosto de 1999): 333–60. http://dx.doi.org/10.2166/nh.1999.0019.
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A field experiment shows that rapid downward migration of solutes and microorganisms can occur in a fractured till. A solute tracer, chloride, and a bacteriophage tracer, PRD-1, were added to groundwater and allowed to infiltrate downwards over a 4 × 4 m area. Chloride was detected in horizontal filters at 2.0 m depth within 3-40 days of the start of the tracer test, and PRD-1 was detected in the same filters within 0.27 - 27 days. At 2.8 m depth chloride appeared in all the filters, but PRD-1 appeared in only about one-third of the filters. At 4.0 m depth chloride appeared in about one-third of the filters and trace amounts of PRD-1 were detected in only 2 of the 36 filters. Transport rates and peak tracer concentrations decreased with depth, but at each depth there was a high degree of variability. The transport data is generally consistent with expectations based on hydraulic conductivity measurements and on the observed density of fractures and biopores, both of which decrease with depth. Transport of chloride was apparently retarded by diffusion into the fine-grained matrix between fractures, but the rapid transport of PRD-1, with little dispersion, indicates that it was transported mainly through the fractures.
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Sire, Yannick y Enrico Valdinoci. "Density estimates for phase transitions with a trace". Interfaces and Free Boundaries 14, n.º 2 (2012): 153–65. http://dx.doi.org/10.4171/ifb/277.
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Hintze, Jerry L. y Ray D. Nelson. "Violin Plots: A Box Plot-Density Trace Synergism". American Statistician 52, n.º 2 (mayo de 1998): 181. http://dx.doi.org/10.2307/2685478.
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Hintze, Jerry L. y Ray D. Nelson. "Violin Plots: A Box Plot-Density Trace Synergism". American Statistician 52, n.º 2 (mayo de 1998): 181–84. http://dx.doi.org/10.1080/00031305.1998.10480559.
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Nicaise, Serge y Adrien Semin. "Density and trace results in generalized fractal networks". ESAIM: Mathematical Modelling and Numerical Analysis 52, n.º 3 (mayo de 2018): 1023–49. http://dx.doi.org/10.1051/m2an/2018021.
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The first aim of this paper is to give different necessary and sufficient conditions that guarantee the density of the set of compactly supported functions into the Sobolev space of order one in infinite p-adic weighted trees. The second goal is to define properly a trace operator in this Sobolev space if it makes sense.
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Matthews, G. F., K. D. Zastrow, P. Andrew, B. Balet, N. P. Basse, J. Ehrenberg, S. K. Erents et al. "Trace tritium and the H-mode density limit". Journal of Nuclear Materials 266-269 (marzo de 1999): 1134–38. http://dx.doi.org/10.1016/s0022-3115(98)00858-7.
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Gao, Yu. "Luminous IR Galaxies: Evolution and Molecular Gas". International Astronomical Union Colloquium 159 (1997): 439–40. http://dx.doi.org/10.1017/s0252921100040690.
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Luminous infrared galaxies (LIRGs), denned by the criterion LIR ≳ 2 × 1011L⊙ (for H0=75 kms−1 Mpc−1), are the most powerful IR sources in the Universe, with most of their emission (~ 90%) in the far-IR. Most LIRGs are interacting/merging galaxies with large amounts of molecular gas as revealed by CO surveys (Sanders et al. 1991; Solomon et al. 1996). However, whether starbursts or dust-enshrouded AGNs/QSOs dominate the IR luminosity is not resolved.CO may not trace the active star-forming regions where gas density is more than one order of magnitude higher than the average. Dense molecular gas is better traced by high dipole-moment molecules like HCN and CS (e.g., Nguyen-Q-Rieu et al. 1992; Gao & Solomon 1996). Therefore, it is essential to survey HCN emission in a large sample of LIRGs to better reveal the nature of LIRGs. We here study IR and molecular gas properties vs. galaxy-galaxy interactions in LIRGs over various merging phases to trace their evolution and explore some links among interactions, starbursts, and AGN phenomena.
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Kirste, Lutz, Karolina Grabianska, Robert Kucharski, Tomasz Sochacki, Boleslaw Lucznik y Michal Bockowski. "Structural Analysis of Low Defect Ammonothermally Grown GaN Wafers by Borrmann Effect X-ray Topography". Materials 14, n.º 19 (22 de septiembre de 2021): 5472. http://dx.doi.org/10.3390/ma14195472.
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X-ray topography defect analysis of entire 1.8-inch GaN substrates, using the Borrmann effect, is presented in this paper. The GaN wafers were grown by the ammonothermal method. Borrmann effect topography of anomalous transmission could be applied due to the low defect density of the substrates. It was possible to trace the process and growth history of the GaN crystals in detail from their defect pattern imaged. Microscopic defects such as threading dislocations, but also macroscopic defects, for example dislocation clusters due to preparation insufficiency, traces of facet formation, growth bands, dislocation walls and dislocation bundles, were detected. Influences of seed crystal preparation and process parameters of crystal growth on the formation of the defects are discussed.