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1
Domènech, Guillem, Roya Mohayaee, Subodh P. Patil et Subir Sarkar. « Galaxy number-count dipole and superhorizon fluctuations ». Journal of Cosmology and Astroparticle Physics 2022, no 10 (1 octobre 2022) : 019. http://dx.doi.org/10.1088/1475-7516/2022/10/019.
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Abstract In view of the growing tension between the dipole anisotropy of number counts of cosmologically distant sources and of the cosmic microwave background (CMB), we investigate the number count dipole induced by primordial perturbations with wavelength comparable to or exceeding the Hubble radius today. First, we find that neither adiabatic nor isocurvature superhorizon modes can generate an intrinsic number count dipole. However a superhorizon isocurvature mode does induce a relative velocity between the CMB and the (dark) matter rest frames and thereby affects the CMB dipole. We revisit the possibility that it has an intrinsic component due to such a mode, thus enabling consistency with the galaxy number count dipole if the latter is actually kinematic in origin. Although this scenario is not particularly natural, there are possible links with other anomalies and it predicts a concommitant galaxy number count quadrupole which may be measurable in future surveys. We also investigate the number count dipole induced by modes smaller than the Hubble radius, finding that subject to CMB constraints this is too small to reconcile the dipole tension.
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Mennucci, Andrea C. G. « On Asymmetric Distances ». Analysis and Geometry in Metric Spaces 1 (11 juin 2013) : 200–231. http://dx.doi.org/10.2478/agms-2013-0004.
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Abstract In this paper we discuss asymmetric length structures and asymmetric metric spaces. A length structure induces a (semi)distance function; by using the total variation formula, a (semi)distance function induces a length. In the first part we identify a topology in the set of paths that best describes when the above operations are idempotent. As a typical application, we consider the length of paths defined by a Finslerian functional in Calculus of Variations. In the second part we generalize the setting of General metric spaces of Busemann, and discuss the newly found aspects of the theory: we identify three interesting classes of paths, and compare them; we note that a geodesic segment (as defined by Busemann) is not necessarily continuous in our setting; hence we present three different notions of intrinsic metric space.
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Valenzuela, Carmen, Eva Delpon, Laura Franqueza, Pilar Gay, Dirk J. Snyders et Juan Tamargo. « Effects of Ropivacaine on a Potassium Channel (hKv1.5) Cloned from Human Ventricle ». Anesthesiology 86, no 3 (1 mars 1997) : 718–28. http://dx.doi.org/10.1097/00000542-199703000-00025.
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Background Ropivacaine, a new amide local anesthetic agent chemically related to bupivacaine, is able to induce early after depolarizations in isolated cardiac preparations. The underlying mechanism by which ropivacaine induces this effect has not been explored, but it is likely to involve K+ channel block. Methods Cloned human cardiac K+ channels (hKv1.5) were stably transfected in Ltk cells, and the effects of ropivacaine on the expressed hKv1.5 currents were assessed using the whole-cell configuration of the patch-clamp technique. Results Ropivacaine (100 microM) did not modify the initial activation time course of the current, but induced a fast subsequent decline to a lower steady-state current level with a time constant of 12.2 +/- 0.6 ms. Ropivacaine inhibited hKv1.5 with an apparent KD of 80 +/- 4 microM. Block displayed an intrinsic voltage-dependent, consistent with an electrical distance for the binding site of 0.153 +/- 0.007 (n = 6) (from the cytoplasmic side). Ropivacaine reduced the tail current amplitude recorded at -40 mV, and slowed the deactivation time course, resulting in a "crossover" phenomenon when control and ropivacaine tail currents were superimposed. Conclusions These results indicate that: (1) ropivacaine is an open channel blocker of hKv1.5; (2) binding occurs in the internal mouth of the ion pore; and (3) unbinding is required before the channel can close. These effects explain the ropivacaine availability of induction early after depolarizations and could be clinically relevant.
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Ritte, Clemens, Robert Cywinski et Sue H. Kilcoyne. « The Nature of the Mn Moment in Laves Phase Compounds : Evolution of the Magnetic Order in Ho1–xYxMn2 ». Zeitschrift für Naturforschung A 50, no 2-3 (1 mars 1995) : 191–98. http://dx.doi.org/10.1515/zna-1995-2-311.
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Abstract Neutron powder diffraction has been used to study the evolution of long range magnetic order in the pseudobinary CI 5 Laves phase system Ho1-xYxMn2. Particular attention has been paid to the nature of the Mn moment. At Y-rich compositions (x > 0.9) an incommensurate antiferromagnetic structure, similar to that of YMn2 is observed. Transition to the ordered state, as in YMn2, is accompanied by a 5% expansion of the unit cell, identifying the Mn moments, of 2.7 μB, as intrinsic. The magnetic structure of compositions with x<0.7 resembles that of HoMn2 and DyMn2, with only one quarter of the chemically equivalent Mn sites possessing a moment of 0.6 μB induced by the local symmetry of the antiferromagnetically ordered Ho sublattice. Transition to the ordered state is not accompanied by a cell expansion. Between x = 0.7 and x = 0.9 there is no longe range magnetic order, nor is there an expansion of the unit cell, suggesting the total absence of either induced or intrinsic Mn moments. The results indicate that a critical Mn-Mn near neighbour distance of 2.663 Å is necessary to sustain an intrinsic Mn moment in these compounds.
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Li, Yuanyuan, Lu Zhang, Tianjie Wang, Jiaxin Xie, Min Wang, Zeming Qi, Qiannan Cui et Jianhua Chang. « All-optically generating and monitoring interlayer expansion of layered GaSe via in situ second harmonic generation ». Applied Physics Letters 122, no 4 (23 janvier 2023) : 043102. http://dx.doi.org/10.1063/5.0135063.
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Interlayer-distance engineering can provide a degree of freedom to tailor the intrinsic physical properties of 2D layered semiconductors and van der Waals heterostructures. In this Letter, we report an all-optical technique to simultaneously generate and monitor interlayer expansions of multilayer GaSe lattice via optical second harmonic generation (SHG). Heat induced by the absorption of fundamental laser can trigger interlayer expansion, while intensity change of SHG caused by mediated superposition of SHG field in expanded layers can monitor the level of interlayer expansion. Our results open an avenue to all-optically engineer interlayer distance of 2D layered semiconductors.
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Kim, Ju Young, Young Taek Oh, Su Eon Lee, Jun Hyun Park, Shin Park, Young Chun Ko, Jun Pyo Hwang et al. « Collapse-Induced Multimer Formation of Self-Assembled Nanoparticles for Surface Enhanced Raman Scattering ». Coatings 11, no 1 (11 janvier 2021) : 76. http://dx.doi.org/10.3390/coatings11010076.
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Metallic nanoparticle ensemble, with narrow inter-particle distance, is a useful element for diverse optical devices due to highly enhanced electric field intensity at the gap. Self-assembly of block copolymer (BCP) can provide the versatile solution to fabricate precise nanostructures, but this methodology has the intrinsic limitation to realize optically coupled metallic multimer geometry with narrow inter-particle distance. This is because BCP-based nanotemplate possesses a minimum size limit for interparticle distance imposed by its thermodynamic restriction. Herein, we investigate the facile formation of metallic multimer with scalability and area-selectivity through the collapse of self-assembled BCP nanopattern. The capillary-force-induced collapse phenomenon enables a spatial transformation of lateral regular ordering in metallic nanoparticle array and enhances electric field intensity. The fabrication of this metallic nanoparticle ensemble from BCP lithography is successfully utilized for surface enhanced Raman scattering (SERS). The enhancement factor of metal nanoparticle multimer is calculated as ~6.74 × 105 at 1000 cm−1, 2.04 × 106 at 1022 cm−1, and 6.11 × 106 at 1580 cm−1, respectively.
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Kim, Ju Young, Young Taek Oh, Su Eon Lee, Jun Hyun Park, Shin Park, Young Chun Ko, Jun Pyo Hwang et al. « Collapse-Induced Multimer Formation of Self-Assembled Nanoparticles for Surface Enhanced Raman Scattering ». Coatings 11, no 1 (11 janvier 2021) : 76. http://dx.doi.org/10.3390/coatings11010076.
Texte intégralRésumé :
Metallic nanoparticle ensemble, with narrow inter-particle distance, is a useful element for diverse optical devices due to highly enhanced electric field intensity at the gap. Self-assembly of block copolymer (BCP) can provide the versatile solution to fabricate precise nanostructures, but this methodology has the intrinsic limitation to realize optically coupled metallic multimer geometry with narrow inter-particle distance. This is because BCP-based nanotemplate possesses a minimum size limit for interparticle distance imposed by its thermodynamic restriction. Herein, we investigate the facile formation of metallic multimer with scalability and area-selectivity through the collapse of self-assembled BCP nanopattern. The capillary-force-induced collapse phenomenon enables a spatial transformation of lateral regular ordering in metallic nanoparticle array and enhances electric field intensity. The fabrication of this metallic nanoparticle ensemble from BCP lithography is successfully utilized for surface enhanced Raman scattering (SERS). The enhancement factor of metal nanoparticle multimer is calculated as ~6.74 × 105 at 1000 cm−1, 2.04 × 106 at 1022 cm−1, and 6.11 × 106 at 1580 cm−1, respectively.
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Wieser, Martin, et Florian H. Müller. « Motivation in Instrumental Music Instruction Before and During the Remote Learning Phase Due to COVID-19 Crisis ». Music & ; Science 5 (janvier 2022) : 205920432211329. http://dx.doi.org/10.1177/20592043221132938.
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This study, which is based on self-determination theory, compares the motivation and satisfaction of basic psychological needs of music students in instrumental lessons before and after the COVID-19-induced transition to online teaching and learning. We investigated whether, in addition to the satisfaction of students’ basic needs, teachers’ enthusiasm, experience with online teaching, and age can explain motivation in online lessons. Two independent groups of music students were surveyed: one group before (n = 856; Mage = 16.4, SD = 14.1) and the other group after the shift to enforced distance learning (n = 640; Mage = 16.7, SD = 13.8). The main findings are that intrinsic motivation in online learning was significantly lower, and controlled forms of motivation higher than before enforced distance learning. Furthermore, satisfaction of basic needs for autonomy, competence, and relatedness, which are essential for autonomous motivation, were lower in online learning. Regression analyses showed that 39% of the variance of intrinsic motivation for online learning could be explained by social relatedness, perceived teacher’s enthusiasm for teaching, and age.
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Zonoozi, Akram Hasani, Hosein Haghi et Pavel Kroupa. « IMF-induced intrinsic uncertainties on measuring galaxy distances based on the number of giant stars : the case of the ultradiffuse galaxy NGC 1052-DF2 ». Monthly Notices of the Royal Astronomical Society 504, no 2 (18 mars 2021) : 1668–75. http://dx.doi.org/10.1093/mnras/stab789.
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ABSTRACT The surface brightness fluctuation (SBF) technique is one of the distance measurement methods that has been applied on the low surface brightness (LSB) galaxy NGC 1052-DF2 yielding a distance of about 20 Mpc implying it to be a dark matter deficient galaxy. We assume the number of giant stars above a given luminosity threshold to represent the SBF magnitude. The SBF magnitude depends on the distance, but this is degenerate with the star formation history (SFH). Using a stellar population synthesis model, we calculate the number of giant stars for stellar populations with different galaxy-wide stellar initial mass functions (gwIMFs), ages, metallicities, and SFHs. If the gwIMF is the invariant canonical IMF, the 1σ (3σ) uncertainty in colour allows a distance as low as 12 Mpc (8 Mpc). If instead the true underlying gwIMF is the integrated galaxy-wide IMF (IGIMF) then overestimating distances for low-mass galaxies would be a natural result, allowing NGC 1052-DF2 to have a distance of 11 Mpc within the 1σ colour uncertainty. Finally, we show that our main conclusion on the existence of a bias in the SBF distance estimation is not much affected by changing the luminosity lower limit for counting giant stars.
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Doroshenko, V., S. Tsygankov et A. Santangelo. « Orbit and intrinsic spin-up of the newly discovered transient X-ray pulsar Swift J0243.6+6124 ». Astronomy & ; Astrophysics 613 (mai 2018) : A19. http://dx.doi.org/10.1051/0004-6361/201732208.
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We present the orbital solution for the newly discovered transient Be X-ray binary Swift J0243.6+6124 based on the data from the gamma-ray burst monitor on board Fermi obtained during the October 2017 outburst. We model the Doppler induced and intrinsic spin variations of the neutron star assuming that the latter is driven by accretion torque, and we discuss the implications of the observed spin variations for the parameters of the neutron star and the binary. In particular, we conclude that the neutron star must be strongly magnetized, and estimate the distance to the source at ~5 kpc.
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Bottinelli, L., L. Gouguenheim, G. Paturel et P. Teerikorpi. « Challenges of Using Planetary Nebulae for Extragalactic Distances ». Highlights of Astronomy 10 (1995) : 504–6. http://dx.doi.org/10.1017/s1539299600011898.
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The planetary nebulae (hereafter PN) distance criterion (Ciardullo et al. 1989a) relies on the shape adopted for the luminosity function (hereafter LF) and its adequate fit to the observed data. Crucial hypothesis concerning the LF are its universal shape with an universal value of the absolute magnitude cut-off and concerning the sample, its completeness and the selection of the rejected data.Because the completeness is achieved only in the bright part of the LF, the brighest PN play a crucial role in the distance determination and it is well known that the brightest objects (with intrinsic scatter) in a giant galaxy are brighter than in a dwarf galaxy. Thus more luminous galaxies are given smaller distances. Because giant galaxies are rare they are not seen at small distances; on the contrary, they are typically observed at large distances. This effect induces a progressive compression of the distance scale.
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Jalalirad, Mohammad, Tufia C. Haddad, Jeffrey L. Salisbury, Derek Radisky, Minzhi Zhang, Mark Schroeder, Ann Tuma et al. « Aurora-A kinase oncogenic signaling mediates TGF-β-induced triple-negative breast cancer plasticity and chemoresistance ». Oncogene 40, no 14 (5 mars 2021) : 2509–23. http://dx.doi.org/10.1038/s41388-021-01711-x.
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AbstractTriple-negative breast cancer (TNBCs) account for 15–20% of all breast cancers and represent the most aggressive subtype of this malignancy. Early tumor relapse and progression are linked to the enrichment of a sub-fraction of cancer cells, termed breast tumor-initiating cells (BTICs), that undergo epithelial to mesenchymal transition (EMT) and typically exhibit a basal-like CD44high/CD24low and/or ALDH1high phenotype with critical cancer stem-like features such as high self-renewal capacity and intrinsic (de novo) resistance to standard of care chemotherapy. One of the major mechanisms responsible for the intrinsic drug resistance of BTICs is their high ALDH1 activity leading to inhibition of chemotherapy-induced apoptosis. In this study, we demonstrated that aurora-A kinase (AURKA) is required to mediate TGF-β-induced expression of the SNAI1 gene, enrichment of ALDH1high BTICs, self-renewal capacity, and chemoresistance in TNBC experimental models. Significantly, the combination of docetaxel (DTX) with dual TGF-β and AURKA pharmacologic targeting impaired tumor relapse and the emergence of distant metastasis. We also showed in unique chemoresistant TNBC cells isolated from patient-derived TNBC brain metastasis that dual TGF-β and AURKA pharmacologic targeting reversed cancer plasticity and enhanced the sensitivity of TNBC cells to DTX-based-chemotherapy. Taken together, these findings reveal for the first time the critical role of AURKA oncogenic signaling in mediating TGF-β-induced TNBC plasticity, chemoresistance, and tumor progression.
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Saar, Drorit, Yoram Grossman et Edi Barkai. « Learning-Induced Enhancement of Postsynaptic Potentials in Pyramidal Neurons ». Journal of Neurophysiology 87, no 5 (1 mai 2002) : 2358–63. http://dx.doi.org/10.1152/jn.2002.87.5.2358.
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We studied the effect of olfactory learning-induced modifications in piriform (olfactory) cortex pyramidal neurons on the propagation of postsynaptic potentials (PSPs). Rats were trained to distinguish between odors in pairs, in an olfactory discrimination task. Three days after training completion, PSPs were evoked in layer II pyramidal cells in piriform cortex brain slices by electrical stimulation of two pathways. Stimulation of layer Ib activated the intra-cortical fibers that terminate on the proximal region of the apical and basal dendrites. Stimulation of layer Ia activated the afferent axons that originate from the olfactory bulb and terminate on the distal apical dendrites. We have previously shown that olfactory training is accompanied by enhanced synaptic transmission in the intrinsic pathway, but not in the afferent pathway at 3 days after training. Here we show that at this stage, in both pathways PSPs evoked in neurons from trained rats had significantly faster rise time measured at the soma compared with PSPs in neurons from pseudo-trained and naive rats. Activation of the slow afterhyperpolarization (AHP), which is generated by potassium channels probably located at the proximal region of both apical and basal dendrites, reduced the amplitude measured at the soma of the proximal intrinsic pathway PSPs more effectively than PSPs that were generated distally by the afferent fibers. Thus the amount of reduction by AHP was used as a measure for the relative distance of PSP-generating sites from the soma. In neurons from trained rats, despite the previously reported reduction in AHP amplitude, AHP conductance shunted the PSPs from both synaptic pathways more efficiently compared with neurons from the control rats. We suggest that in neurons from trained rats PSPs are electrotonicly closer to the soma.
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Stroo, Ingrid, Chao Ding, Andreja Novak, Jack Yang, Joris J. T. H. Roelofs, Joost C. M. Meijers, Alexey S. Revenko et al. « Inhibition of the extrinsic or intrinsic coagulation pathway during pneumonia-derived sepsis ». American Journal of Physiology-Lung Cellular and Molecular Physiology 315, no 5 (1 novembre 2018) : L799—L809. http://dx.doi.org/10.1152/ajplung.00014.2018.
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Pneumonia is the most frequent cause of sepsis, and Klebsiella pneumoniae is a common pathogen in pneumonia and sepsis. Infection is associated with activation of the coagulation system. Coagulation can be activated by the extrinsic and intrinsic routes, mediated by factor VII (FVII) and factor XII (FXII), respectively. To determine the role of FVII and FXII in the host response during pneumonia-derived sepsis, mice were treated with specific antisense oligonucleotide (ASO) directed at FVII or FXII for 3 wk before infection with K. pneumoniae via the airways. FVII ASO treatment strongly inhibited hepatic FVII mRNA expression, reduced plasma FVII to ~25% of control, and selectively prolonged the prothrombin time. FXII ASO treatment strongly suppressed hepatic FXII mRNA expression, reduced plasma FXII to ~20% of control, and selectively prolonged the activated partial thromboplastin time. Lungs also expressed FVII mRNA, which was not altered by FVII ASO administration. Very low FXII mRNA levels were detected in lungs, which were not modified by FXII ASO treatment. FVII ASO attenuated systemic activation of coagulation but did not influence fibrin deposition in lung tissue. FVII ASO enhanced bacterial loads in lungs and mitigated sepsis-induced distant organ injury. FXII inhibition did not affect any of the host response parameters measured. These results suggest that partial inhibition of FVII, but not of FXII, modifies the host response to gram-negative pneumonia-derived sepsis.
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Jiang, Shang, Jianguo Jiang, Siye Wang, Yanfang Zhang, Yue Feng, Ziwen Cao et Yi Liu. « RF-Gait : Gait-Based Person Identification with COTS RFID ». Wireless Communications and Mobile Computing 2022 (4 juin 2022) : 1–14. http://dx.doi.org/10.1155/2022/3638436.
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Recently, person identification has been a prerequisite in many applications of the Internet of Things. As a new biometric identification technology, gait recognition has a wide application prospect with the advantages of long-distance recognition and difficulty to forge. However, the existing gait recognition methods have some problems, such as complex algorithm calculation, high user participation, and large equipment overhead. In this paper, we propose RF-Gait, a method that identifies a person through unobtrusive gait perception with COTS RFID. The key insight is that wireless signal fluctuation can be exploited to distinguish each person’s unique gait behavior. To this end, we first collect and preprocess the gait-induced data composed of multiple RFID tags. Furthermore, multivariate variational mode decomposition is utilized to extract the intrinsic features in the spatial multichannels cooperatively. By developing a support vector machine model, we identify a person via the intrinsic walking pattern. Finally, extensive experiments show that our method can identify a person with an average accuracy of 96.3% from a group of twenty persons in a complex indoor environment.
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Egan, Hilary, Riku Jarvinen, Yingjuan Ma et David Brain. « Planetary magnetic field control of ion escape from weakly magnetized planets ». Monthly Notices of the Royal Astronomical Society 488, no 2 (3 juillet 2019) : 2108–20. http://dx.doi.org/10.1093/mnras/stz1819.
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ABSTRACT Intrinsic magnetic fields have long been thought to shield planets from atmospheric erosion via stellar winds; however, the influence of the plasma environment on atmospheric escape is complex. Here we study the influence of a weak intrinsic dipolar planetary magnetic field on the plasma environment and subsequent ion escape from a Mars-sized planet in a global three-dimensional hybrid simulation. We find that increasing the strength of a planet’s magnetic field enhances ion escape until the magnetic dipole’s standoff distance reaches the induced magnetosphere boundary. After this point increasing the planetary magnetic field begins to inhibit ion escape. This reflects a balance between shielding of the Southern hemisphere from ‘misaligned’ ion pickup forces and trapping of escaping ions by an equatorial plasmasphere. Thus, the planetary magnetic field associated with the peak ion escape rate is critically dependent on the stellar wind pressure. Where possible we have fit power laws for the variation of fundamental parameters (escape rate, escape power, polar cap opening angle, and effective interaction area) with magnetic field, and assessed upper and lower limits for the relationships.
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Tiwari, Prince. « Fluorescence-based Techniques to Study the Structure and Dynamics of Mass-selected Biomolecular Ions ». CHIMIA International Journal for Chemistry 75, no 4 (28 avril 2021) : 252–56. http://dx.doi.org/10.2533/chimia.2021.252.
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Laser-induced fluorescence studies on mass-selected biomolecules are a promising route to understand their properties in the gas phase and probe their intrinsic properties in a solvent-free environment. Fluorescence has been used to investigate the conformation and dynamics of gaseous biomolecular ions. With Förster Resonance Energy Transfer (FRET), it is now possible to obtain sensitive intramolecular distance information from large biomolecules, like proteins, with high chemical specificity. With growing interest and applications, gas-phase fluorescence measurements can shed greater light on the characteristics of proteins in the gas phase. Compared to the solution phase measurements, gas-phase fluorescence can also help understand the influence of solvent interactions on the protein structure and function.
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Segal, S. S., D. N. Damon et B. R. Duling. « Propagation of vasomotor responses coordinates arteriolar resistances ». American Journal of Physiology-Heart and Circulatory Physiology 256, no 3 (1 mars 1989) : H832—H837. http://dx.doi.org/10.1152/ajpheart.1989.256.3.h832.
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We tested the hypothesis that a conduction pathway intrinsic to the arteriolar wall possesses the properties necessary to coordinate vasomotor responses in the microcirculation. Acetylcholine (ACh) or norepinephrine (NE) was iontophoresed onto cheek pouch arterioles (15-35 microns diam) of pentobarbital-anesthetized hamsters, and diameter responses were observed using intravital video microscopy. ACh and NE induced vasodilation and vasoconstriction, respectively, that propagated both upstream and downstream from the site of application. Propagated vasomotor responses decayed with distance along the arterioles; this decay was characterized by mechanical length constants of 1.9 and 1.8 mm for ACh and NE, respectively. Vasodilations and vasoconstrictions initiated on daughter vessels of a branch propagated into parent arterioles that were approximately twice the diameter of the daughter vessels. Iontophoretic stimuli applied simultaneously to paired daughter vessels induced propagated responses that summed linearly in the parent vessel. We conclude that the arteriolar network functions as a highly coordinated syncytium and that diverse vasomotor stimuli can be summed and integrated within the peripheral microvasculature.
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Stiperski, Ivana, et Vanda Grubišić. « Trapped Lee Wave Interference in the Presence of Surface Friction ». Journal of the Atmospheric Sciences 68, no 4 (1 avril 2011) : 918–36. http://dx.doi.org/10.1175/2010jas3495.1.
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Abstract Trapped lee wave interference over double bell-shaped obstacles in the presence of surface friction is examined. Idealized high-resolution numerical experiments with the nonhydrostatic Coupled Ocean–Atmosphere Mesoscale Prediction System (COAMPS) are performed to examine the influence of a frictional boundary layer and nonlinearity on wave interference and the impact of interference on wave-induced boundary layer separation and the formation of rotors. The appearance of constructive and destructive interference, controlled by the ratio of the ridge separation distance to the intrinsic horizontal wavelength of lee waves, is found to be predicted well by linear interference theory with orographic adjustment. The friction-induced shortening of intrinsic wavelength displays a strong indirect effect on wave interference. For twin peak orography, the interference-induced variation of wave amplitude is smaller than that predicted by linear theory. The interference is found to affect the formation and strength of rotors most significantly in the lee of the downstream peak; destructive interference suppresses the formation and strength of rotors there, whereas results for constructive interference closely parallel those for a single mountain. Over the valley, under both constructive and destructive interference, rotors are weaker compared to those in the lee of a single ridge while their strength saturates in the finite-amplitude flow regime. Destructive interference is found to be more susceptible to nonlinear effects, with both the orographic adjustment and surface friction displaying a stronger effect on the flow in this state. “Complete” destructive interference, in which waves almost completely cancel out in the lee of the downstream ridge, develops for certain ridge separation distances but only for a downstream ridge smaller than the upstream one.
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Zhang, Yan Hui, et Wen Yu Yang. « A FBG-Based Robust Damage Identification Approach Considering Environmental and Operational Conditions Effects ». Applied Mechanics and Materials 556-562 (mai 2014) : 3255–58. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.3255.
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This paper researches a robust damage identification system considering the effects of the environmental and operational conditions based on distributed fiber Bragg grating system. Initially a well-verified method is used to identify damage, but the failure result is obtained. The environmental and operational variations causing the false-positive indication are analyzed, such as the temperature, the change of the excitation and the relaxation phenomenon of the sensors. The Hilbert-Huang Transform method is used to decompose the dynamic strain signal into several intrinsic mode function components, the physical meanings of which are discussed. Then the second level component is used as the damage-induced signal component. Lastly the damage index based on the autoregressive model and Mahalanobis distance is constructed to detect and locate damage.
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Zhou, Qi-Qi, Shuang-Xi Yi, Jun-Jie Wei et Xue-Feng Wu. « Constraints on Lorentz Invariance Violation with Multiwavelength Polarized Astrophysical Sources ». Galaxies 9, no 2 (20 juin 2021) : 44. http://dx.doi.org/10.3390/galaxies9020044.
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Possible violations of Lorentz invariance (LIV) can produce vacuum birefringence, which results in a frequency-dependent rotation of the polarization plane of linearly polarized light from distant sources. In this paper, we try to search for a frequency-dependent change of the linear polarization angle arising from vacuum birefringence in the spectropolarimetric data of astrophysical sources. We collect five blazars with multiwavelength polarization measurements in different optical bands (UBVRI). Taking into account the observed polarization angle contributions from both the intrinsic polarization angle and the rotation angle induced by LIV, and assuming that the intrinsic polarization angle is an unknown constant, we obtain new constraints on LIV by directly fitting the multiwavelength polarimetric data of the five blazars. Here, we show that the birefringence parameter η quantifying the broken degree of Lorentz invariance is limited to be in the range of −9.63×10−8<η<6.55×10−6 at the 2σ confidence level, which is as good as or represents one order of magnitude improvement over the results previously obtained from ultraviolet/optical polarization observations. Much stronger limits can be obtained by future multiwavelength observations in the gamma-ray energy band.
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Kotál, Jan, Stéphanie G. I. Polderdijk, Helena Langhansová, Monika Ederová, Larissa A. Martins, Zuzana Beránková, Adéla Chlastáková et al. « Ixodes ricinus Salivary Serpin Iripin-8 Inhibits the Intrinsic Pathway of Coagulation and Complement ». International Journal of Molecular Sciences 22, no 17 (31 août 2021) : 9480. http://dx.doi.org/10.3390/ijms22179480.
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Tick saliva is a rich source of antihemostatic, anti-inflammatory, and immunomodulatory molecules that actively help the tick to finish its blood meal. Moreover, these molecules facilitate the transmission of tick-borne pathogens. Here we present the functional and structural characterization of Iripin-8, a salivary serpin from the tick Ixodes ricinus, a European vector of tick-borne encephalitis and Lyme disease. Iripin-8 displayed blood-meal-induced mRNA expression that peaked in nymphs and the salivary glands of adult females. Iripin-8 inhibited multiple proteases involved in blood coagulation and blocked the intrinsic and common pathways of the coagulation cascade in vitro. Moreover, Iripin-8 inhibited erythrocyte lysis by complement, and Iripin-8 knockdown by RNA interference in tick nymphs delayed the feeding time. Finally, we resolved the crystal structure of Iripin-8 at 1.89 Å resolution to reveal an unusually long and rigid reactive center loop that is conserved in several tick species. The P1 Arg residue is held in place distant from the serpin body by a conserved poly-Pro element on the P′ side. Several PEG molecules bind to Iripin-8, including one in a deep cavity, perhaps indicating the presence of a small-molecule binding site. This is the first crystal structure of a tick serpin in the native state, and Iripin-8 is a tick serpin with a conserved reactive center loop that possesses antihemostatic activity that may mediate interference with host innate immunity.
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Tsai, Shih-Chang, San-Lein Wu, Jone-Fang Chen, Bo-Chin Wang, Po Chin Huang, Kai-Shiang Tsai, Tsung-Hsien Kao et al. « Investigation of Low-Frequency Noise Characterization of 28-nm High-k pMOSFET with Embedded SiGe Source/Drain ». Journal of Nanomaterials 2014 (2014) : 1–6. http://dx.doi.org/10.1155/2014/787132.
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We have studied the low-frequency noise characterizations in 28-nm high-k (HK) pMOSFET with embedded SiGe source/drain (S/D) through1/f noise and random telegraph noise measurements simultaneously. It is found that uniaxial compressive strain really existed in HK pMOSFET with embedded SiGe S/D. The compressive strain induced the decrease in the tunneling attenuation length reflecting in the oxide trap depth from Si/SiO2interface to the HK layer, so that the oxide traps at a distance from insulator/semiconductor interface cannot capture carrier in the channel. Consequently, lower1/f noise level in HK pMOSFET with embedded SiGe S/D is observed, thanks to the less carrier fluctuations from trapping/detrapping behaviors. This result represents an intrinsic benefit of HK pMOSFET using embedded SiGe S/D in low-frequency noise characteristics.
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Aqbi, Hussein F., Timothy Smith, Savannah Butler, Michael Idowu, Kyle K. Payne et Masoud H. Manjili. « Autophagy-deficient breast cancer shows early escape from dormancy and recurrence following chemotherapy ». Journal of Immunology 200, no 1_Supplement (1 mai 2018) : 122.23. http://dx.doi.org/10.4049/jimmunol.200.supp.122.23.
Texte intégralRésumé :
Abstract Breast cancer patients who respond to cancer therapies often end up with a distant recurrence of the disease. It is not clear why people with the same type of breast cancer respond to treatments differently, some escape from dormancy and relapse earlier than others. In addition, some tumor clones respond to immunotherapy while others do not. Here, we investigated the role of autophagy in expediting or delaying recurrence of neu overexpressing mammary carcinoma (MMC) following adriamycin (ADR) chemotherapy, and in affecting response to immunotherapy. We took two strategies, including a transient blockade of autophagy with chloroquine (CQ) which transiently blocks fusion of autophagosome and lysosome, and a stable knockdown of autophagy, which inhibits the formation of autophagosome in MMC. We found that while CQ prolonged tumor dormancy, a stable knockdown of autophagy resulted in early escape from dormancy and recurrence. Interestingly, MMC with a stable knockdown of autophagy contained an increased frequency of ADR-induced polyploidy cells which rendered MMC resistant to immunotherapy. On the other hand, a transient blockade of autophagy did not affect the sensitivity of MMC to immunotherapy. Our observations suggest that while chemotherapy-induced autophagy may facilitate tumor relapse, cell intrinsic autophagy delays tumor relapse by inhibiting the formation of polyploidy tumor cells. Our findings are consistent with other reports showing that autophagy-deficient cells contain polyploid nuclei because of increased levels of reactive oxygen species. Our results also suggest that responsiveness of breast cancer patients to neoadjuvant therapies might be determined by tumor intrinsic autophagy.
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Li, Yun, Haoyu Lu, Jinbin Cao, Shibang Li, Christian Mazelle et Guokan Li. « Three-dimensional Multispecies Simulation of the Solar Wind Interaction with Mars Under Different Interplanetary Magnetic Field Orientations ». Astrophysical Journal 921, no 2 (1 novembre 2021) : 139. http://dx.doi.org/10.3847/1538-4357/ac1ce5.
Texte intégralRésumé :
Abstract Without the intrinsic magnetic field, the solar wind interaction with Mars can be significantly different from the interaction with Earth and other magnetized planets. In this paper, we investigate how a global configuration of the magnetic structures, consisting of the bow shock, the induced magnetosphere, and the magnetotail, is modulated by the interplanetary magnetic field (IMF) orientation. A 3D multispecies numerical model is established to simulate the interaction of solar wind with Mars under different IMF directions. The results show that the shock size including the subsolar distance and the terminator radius increases with Parker spiral angle, as is the same case with the magnetotail radius. The location and shape of the polarity reversal layer and inverse polarity reversal layer in the induced magnetotail are displaced to the y < 0 sector for a nonzero flow-aligned IMF component, consistent with previous analytical solutions and observations. The responses of the Martian global magnetic configuration to the different IMF directions suggest that the external magnetic field plays an important role in the solar wind interaction with unmagnetized planets.
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Wong, Laura Elisabeth, Molly E. Gibson, H. Moore Arnold, Blake Pepinsky et Eric Frank. « Artemin promotes functional long-distance axonal regeneration to the brainstem after dorsal root crush ». Proceedings of the National Academy of Sciences 112, no 19 (27 avril 2015) : 6170–75. http://dx.doi.org/10.1073/pnas.1502057112.
Texte intégralRésumé :
Recovery after a spinal cord injury often requires that axons restore synaptic connectivity with denervated targets several centimeters from the site of injury. Here we report that systemic artemin (ARTN) treatment promotes the regeneration of sensory axons to the brainstem after brachial dorsal root crush in adult rats. ARTN not only stimulates robust regeneration of large, myelinated sensory axons to the brainstem, but also promotes functional reinnervation of the appropriate target region, the cuneate nucleus. ARTN signals primarily through the RET tyrosine kinase, an interaction that requires the nonsignaling coreceptor GDNF family receptor (GFRα3). Previous studies reported limited GFRα3 expression on large sensory neurons, but our findings demonstrate that ARTN promotes robust regeneration of large, myelinated sensory afferents. Using a cell sorting technique, we demonstrate that GFRα3 expression is similar in myelinated and unmyelinated adult sensory neurons, suggesting that ARTN likely induces long-distance regeneration by binding GFRα3 and RET. Although ARTN is delivered for just 2 wk, regeneration to the brainstem requires more than 3 mo, suggesting that brief trophic support may initiate intrinsic growth programs that remain active until targets are reached. Given its ability to promote targeted functional regeneration to the brainstem, ARTN may represent a promising therapy for restoring sensory function after spinal cord injury.
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McMullen, T., P. Jena et S. N. Khanna. « Screening of a Positive Muon by a Semion Gas ». International Journal of Modern Physics B 05, no 10 (juin 1991) : 1579–88. http://dx.doi.org/10.1142/s0217979291001486.
Texte intégralRésumé :
μSR is one of the experimental techniques used to search for manifestations of the broken [Formula: see text] and [Formula: see text] symmetries predicted by some theories of highly correlated electron systems. When [Formula: see text] and [Formula: see text] are broken, the screening of the positively charged muon by the electron system generates a magnetic field in addition to any intrinsic magnetic field that may be present. We estimate the magnetic field that is induced at a muon site when the muon is screened by the fractional statistics gas. The value depends on the distance between the muon and the anyon plane, and a simple theoretical approach to the calculation of the minimum energy muon sites is outlined and some results for Bi 2 Sr 2 CaCu 2 O 8 and YBa 2 Cu 3 O 7 are presented.
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Jia, Baohui, Zhishun Liu, Baoquan Min, Zhenchang Wang, Aihong Zhou, Yong Li, Haifa Qiao et Jianping Jia. « The Effects of Acupuncture at Real or Sham Acupoints on the Intrinsic Brain Activity in Mild Cognitive Impairment Patients ». Evidence-Based Complementary and Alternative Medicine 2015 (2015) : 1–9. http://dx.doi.org/10.1155/2015/529675.
Texte intégralRésumé :
Accumulating neuroimaging studies in humans have shown that acupuncture can modulate a widely distributed brain network in mild cognitive impairment (MCI) and Alzheimer’s disease (AD) patients. Acupuncture at different acupoints could exert different modulatory effects on the brain network. However, whether acupuncture at real or sham acupoints can produce different effects on the brain network in MCI or AD patients remains unclear. Using resting-state fMRI, we reported that acupuncture at Taixi (KI3) induced amplitude of low-frequency fluctuation (ALFF) change of different brain regions in MCI patients from those shown in the healthy controls. In MCI patients, acupuncture at KI3 increased or decreased ALFF in the different regions from those activated by acupuncture in the healthy controls. Acupuncture at the sham acupoint in MCI patients activated the different brain regions from those in healthy controls. Therefore, we concluded that acupuncture displays more significant effect on neuronal activities of the above brain regions in MCI patients than that in healthy controls. Acupuncture at KI3 exhibits different effects on the neuronal activities of the brain regions from acupuncture at sham acupoint, although the difference is only shown at several regions due to the close distance between the above points.
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Choudhury, Feroza K. « Mitochondrial Redox Metabolism : The Epicenter of Metabolism during Cancer Progression ». Antioxidants 10, no 11 (19 novembre 2021) : 1838. http://dx.doi.org/10.3390/antiox10111838.
Texte intégralRésumé :
Mitochondrial redox metabolism is the central component in the cellular metabolic landscape, where anabolic and catabolic pathways are reprogrammed to maintain optimum redox homeostasis. During different stages of cancer, the mitochondrial redox status plays an active role in navigating cancer cells’ progression and regulating metabolic adaptation according to the constraints of each stage. Mitochondrial reactive oxygen species (ROS) accumulation induces malignant transformation. Once vigorous cell proliferation renders the core of the solid tumor hypoxic, the mitochondrial electron transport chain mediates ROS signaling for bringing about cellular adaptation to hypoxia. Highly aggressive cells are selected in this process, which are capable of progressing through the enhanced oxidative stress encountered during different stages of metastasis for distant colonization. Mitochondrial oxidative metabolism is suppressed to lower ROS generation, and the overall cellular metabolism is reprogrammed to maintain the optimum NADPH level in the mitochondria required for redox homeostasis. After reaching the distant organ, the intrinsic metabolic limitations of that organ dictate the success of colonization and flexibility of the mitochondrial metabolism of cancer cells plays a pivotal role in their adaptation to the new environment.
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Zhang, Deng, Xingjian Yan, Liang She, Yunqing Wen et Mu-ming Poo. « Global enhancement of cortical excitability following coactivation of large neuronal populations ». Proceedings of the National Academy of Sciences 117, no 33 (3 août 2020) : 20254–64. http://dx.doi.org/10.1073/pnas.1914869117.
Texte intégralRésumé :
Correlated activation of cortical neurons often occurs in the brain and repetitive correlated neuronal firing could cause long-term modifications of synaptic efficacy and intrinsic excitability. We found that repetitive optogenetic activation of neuronal populations in the mouse cortex caused enhancement of optogenetically evoked firing of local coactivated neurons as well as distant cortical neurons in both ipsilateral and contralateral hemispheres. This global enhancement of evoked responses required coactivation of a sufficiently large population of neurons either within one cortical area or distributed in several areas. Enhancement of neuronal firing was saturable after repeated episodes of coactivation, diminished by inhibition ofN-methyl-d-aspartic acid receptors, and accompanied by elevated excitatory postsynaptic potentials, all consistent with activity-induced synaptic potentiation. Chemogenetic inhibition of neuronal activity of the thalamus decreased the enhancement effect, suggesting thalamic involvement. Thus, correlated excitation of large neuronal populations leads to global enhancement of neuronal excitability.
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Cao, Xiang Yu, Jian Li Liu, Xiu Li Lu, Tie Min Li, Wei Wang et Qi Jiu Li. « Study on the Interaction between 3, 5-Dinitrobenzoic Acid and Bovine Serum Albumin by Fluorescence Spectroscopic Method ». Advanced Materials Research 233-235 (mai 2011) : 113–16. http://dx.doi.org/10.4028/www.scientific.net/amr.233-235.113.
Texte intégralRésumé :
The interaction between 3, 5-dinitrobenzoic acid and bovine serum albumin (BSA) was studied by the method of fluorescence spectroscopy. By the analysis of fluorescence spectra and fluorescence intensity, it was observed that the 3, 5-dinitrobenzoic acid had a strong ability to quench the intrinsic fluorescence of BSA through static quenching process. Based on fluorescence quenching results, the apparent binding constant (K) between 3, 5-dinitrobenzoic acid and BSA was 7.08×106 and the number of binding sites (n) was 1.5 at 298 K. The distance (r) between donor (BSA) and acceptor (3, 5-dinitrobenzoic) was 4.17 nm according to the Förster’s theory of non-radiation energy transfer. The negative △H and △Sin case of 3,5-dinitrobenzoic acid-BSA complex showed that hydrogen bonds and van der Waals force played a significant role in the binding of 3,5-dinitrobenzoic acid to BSA. The synchronous fluorescence spectra revealed that 3, 5-dinitrobenzoic acid induced conformational change of BSA.
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Lin, Huey-Jiuan, et Hsuan-Chung Wu. « Electronic Structure and Optical Properties of N/Si-Codoped Anatase TiO2Evaluated Using First Principles Calculations ». International Journal of Photoenergy 2014 (2014) : 1–7. http://dx.doi.org/10.1155/2014/342132.
Texte intégralRésumé :
First principles calculations were used to evaluate the electronic structure and optical properties of N/Si-monodoped and N/Si-codoped TiO2to further understand their photocatalytic mechanisms. In accordance with the atomic distance between N and Si dopants, this study considered three N/Si codoping configurations, in which the N dopant had a tendency to bond with the Si dopant. The calculations showed that the bandgaps of the N/Si codoping models were narrow, in the range 3.01–3.05 eV, redshifting the intrinsic absorption edge. The Si 3porbital of N/Si-codoped TiO2plays a key role in widening the valence band (VB), thereby increasing carrier mobility. In addition, the N-induced impurity energy level in the forbidden band appears in all three N/Si codoping models, strengthening absorption in the visible region. The bandgap narrowing, VB widening, and impurity energy levels in the forbidden band are beneficial for improving the photocatalytic activity of N/Si-codoped TiO2.
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Brainerd, Tereasa G., Roger D. Blandford et Ian Smail. « Weak Lensing By Individual Galaxies ». Symposium - International Astronomical Union 173 (1996) : 183–88. http://dx.doi.org/10.1017/s0074180900231252.
Texte intégralRésumé :
In this paper we report on an investigation of statistical weak gravitational lensing of cosmologically distant faint galaxies by foreground galaxies. The signal we seek is a distortion of the images of faint galaxies resulting in a weakly preferred tangential alignment of faint galaxies around brighter galaxies. That is, if the faint galaxies have been gravitationally lensed by the brighter systems, the major axes of their images will tend to lie perpendicular to the radius vectors joining the centroids of the faint and bright galaxies (Fig. 1). Modeling a lens galaxy as a singular isothermal sphere with circular velocity Vc, an ellipticity of ∼ 2πVc2 /c2θ is induced in the image of a source galaxy at an angular separation θ from the lens. This is of order a few percent for faint–bright galaxy pairs with separations θ ∼ 30″ where the lens is a typical bright spiral. Over 1000 pairs must be measured in order to detect such a signal in the presence of the noise associated with the intrinsic galaxy shapes. Given a sufficiently large number of pairs, it may be possible to use the variation of the induced ellipticity with θ to study the angular extent of the halos of the lens galaxies.
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Ren, Qihao, Weng Hua Khoo, Jiayu Ye, Douglas V. Faget, Peter I. Croucher et Sheila A. Stewart. « Abstract 2450 : Investigating the intrinsic and extrinsic factors regulating breast cancer dormancy ». Cancer Research 82, no 12_Supplement (15 juin 2022) : 2450. http://dx.doi.org/10.1158/1538-7445.am2022-2450.
Texte intégralRésumé :
Abstract Unfortunately, breast cancer can recur in patients upwards of 25 years after an initial diagnosis and “cure”. It was once thought that recurrence occurred within patients that harbored dormant breast disseminated tumor cells (DTCs) in distant organs that were not present in patients that did not recur. Interestingly, a significant percent of patients harbor DTCs, yet many do not recur, raising the critical question, what differentiates patients that experience a recurrence versus those who live with dormant DTCs for the rest of their lives? It is likely the answer lies in both cell intrinsic as well as extrinsic factors. Nevertheless, the extreme rarity of dormant DTCs has been the major obstacle to their study. To overcome this challenge, we developed an efficient system to isolate and study rare dormant tumor cells from metastatic organs. Using this system and single cell RNA-sequencing (scRNA-seq), we identified a group of genes differentially expressed in dormant breast cancer cells present in both bone and lung. While modulation of these genes individually had no impact on the metastatic behavior of breast cancer cells, we found that as a group, these genes predicted the dormancy phenotype in murine breast cancer models. Importantly, expression of these genes in primary human breast cancer tumors correlated with disease-free survival, suggesting these genes have predictive value in determining which patients are likely to recur. Moreover, we explored extrinsic mechanisms that impact dormancy and found that the chemotherapy reagent doxorubicin (Doxo) drastically changed the microenvironment in vivo, which allowed dormant breast cancer cells to grow robustly within the visceral fat and this was further exacerbated by a high fat diet. Further, we found that Doxo treatment induces significant adipose tissue dystrophy and macrophage infiltration, which may contribute to dormant metastatic outgrowth. Our study provides novel insight into breast cancer dormancy, and also reveals microenvironmental changes that impact dormant breast cancer cell outgrowth. Citation Format: Qihao Ren, Weng Hua Khoo, Jiayu Ye, Douglas V. Faget, Peter I. Croucher, Sheila A. Stewart. Investigating the intrinsic and extrinsic factors regulating breast cancer dormancy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2450.
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Feuillebois, François, Maria L. Ekiel-Jeżewska, Eligiusz Wajnryb, Antoine Sellier et Jerzy Bławzdziewicz. « High-frequency viscosity of a dilute suspension of elongated particles in a linear shear flow between two walls ». Journal of Fluid Mechanics 764 (23 décembre 2014) : 133–47. http://dx.doi.org/10.1017/jfm.2014.690.
Texte intégralRésumé :
AbstractA general expression for the effective viscosity of a dilute suspension of arbitrary-shaped particles in linear shear flow between two parallel walls is derived in terms of the induced stresslets on particles. This formula is applied to $N$-bead rods and to prolate spheroids with the same length, aspect ratio and volume. The effective viscosity of non-Brownian particles in a periodic shear flow is considered here. The oscillating frequency is high enough for the particle orientation and centre-of-mass distribution to be practically frozen, yet small enough for the flow to be quasi-steady. It is known that for spheres, the intrinsic viscosity $[{\it\mu}]$ increases monotonically when the distance $H$ between the walls is decreased. The dependence is more complex for both types of elongated particles. Three regimes are theoretically predicted here: (i) a ‘weakly confined’ regime (for $H>l$, where $l$ is the particle length), where $[{\it\mu}]$ is slightly larger for smaller $H$; (ii) a ‘semi-confined’ regime, when $H$ becomes smaller than $l$, where $[{\it\mu}]$ rapidly decreases since the geometric constraints eliminate particle orientations corresponding to the largest stresslets; (iii) a ‘strongly confined’ regime when $H$ becomes smaller than 2–3 particle widths $d$, where $[{\it\mu}]$ rapidly increases owing to the strong hydrodynamic coupling with the walls. In addition, for sufficiently slender particles (with aspect ratio larger than 5–6) there is a domain of narrow gaps for which the intrinsic viscosity is smaller than that in unbounded fluid.
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Suyono, Handi, Kristian Sanjaya et Deby Susanti. « The Role of Antiapoptotic Erythropoietin on Ultraviolet B-Induced Photodamaged Skin Through Inhibition of Sunburn Cells ». Folia Medica Indonesiana 56, no 2 (6 août 2020) : 114. http://dx.doi.org/10.20473/fmi.v56i2.21229.
Texte intégralRésumé :
Ultraviolet light causes photodamaged skin leading to photoaging skin. Ultraviolet-B (UV-B) causes epidermal keratinocyte apoptosis, namely sunburn cell, through apoptotic intrinsic pathway. Erythropoietin (EPO) has a role in cytoprotection in various tissues but its role to epidermal skin is not clear yet. This study was designed pretest-posttest control group design. Thirty two male mice Mus musculus, strain Balbc, were divided into control and treatment group, 16 mice each group. All mice were exposured by UV-B light 16mJ/cm2, distance 30 cm, duration 90 seconds, for 3 consecutive days. Four mice each group were randomly sacrificed as pretest data. The control mice were given aquadest subcutaneous injection 0.1 mL, and treatment mice were given EPO subcutaneous injection 0.1 mL (100 IU/kg BW). UVB were given everyday with same protocol above. Treatments were given 4 times, interval 3 days. All mice were sacrificed to examine sunburn cells. Data were performed as mean ± SD and analyzed by t-test using SPSS 17.0 with significant value p<0.05. Sunburn cells of pretest control were 25.00 ± 4.85% and treatment group were 24.83 ± 5.15%. Sunburn cells significantly decreased (p=0.002) in treatment group (31.5 ± 9.39%) than control (50.83 ± 6.70%). UV-B causes sunburn cells formation. EPO inhibits apoptosis through increasing NO production and eNOS expression, inhibiting caspase and proinflammatory cytokines, and increasing antiapoptotic protein. EPO has a role in skin apoptosis inhibition which is shown by decreased sunburn cells
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Biella, Gerardo, Laura Uva, Ulrich G. Hofmann et Marco De Curtis. « Associative Interactions Within the Superficial Layers of the Entorhinal Cortex of the Guinea Pig ». Journal of Neurophysiology 88, no 3 (1 septembre 2002) : 1159–65. http://dx.doi.org/10.1152/jn.2002.88.3.1159.
Texte intégralRésumé :
Associative fiber systems in the entorhinal cortex (EC) have been extensively studied in different mammals with tracing techniques. The largest contingent of intra-EC cortico-cortical fibers runs in the superficial layers and is distributed predominantly within longitudinal cortical bands. We studied the patterns of intrinsic EC connectivity in the in vitro isolated guinea pig brain preparation by performing current-source density analysis of field potential laminar profiles recorded with multi-channel silicon probes. The response pattern evoked by stimulation of the lateral olfactory tract was utilized to identify the lateral (l-EC) and medial (m-EC) entorhinal cortex. Stimulation of the deep layers did not evoke consistent responses. Local stimulation of the superficial layers in different portions of the EC induced an early, possibly direct response restricted to layer II–III in the close proximity to the stimulating electrode, followed by a late potential in the superficial layer I, that propagated at distance with a progressively increasing latency. The monosynaptic nature of the delayed response was verified by applying a pairing test. The results demonstrated that stimulation in the rostral-medial part of the EC generated activity restricted to the rostral pole of the l-EC, stimulation of the m-EC induced an associative activation that propagated rostrocaudally within the m-EC, stimulation of the caudal pole of the m-EC induced an additional response directed laterally, and stimulation of the lateral band of the EC determined a prominent longitudinal propagation of neuronal activity, but also induced associative potentials that propagated medially. The results are in partial agreement with the general picture derived from the anatomical studies performed in different species. Even though the largest associative interactions between superficial layers are restricted within either the m-EC or the l-EC, both rostral and caudal stimuli in the EC region close to the rhinal sulcus induced activity that propagated across the border between l- and m-EC.
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Hilla, Alexander M., Annemarie Baehr, Marco Leibinger, Anastasia Andreadaki et Dietmar Fischer. « CXCR4/CXCL12-mediated entrapment of axons at the injury site compromises optic nerve regeneration ». Proceedings of the National Academy of Sciences 118, no 21 (19 mai 2021) : e2016409118. http://dx.doi.org/10.1073/pnas.2016409118.
Texte intégralRésumé :
Regenerative failure in the mammalian optic nerve is generally attributed to axotomy-induced retinal ganglion cell (RGC) death, an insufficient intrinsic regenerative capacity, and an extrinsic inhibitory environment. Here, we show that a chemoattractive CXCL12/CXCR4-dependent mechanism prevents the extension of growth-stimulated axons into the distal nerve. The chemokine CXCL12 is chemoattractive toward axonal growth cones in an inhibitory environment, and these effects are entirely abolished by the specific knockout of its receptor, CXCR4 (CXCR4−/−), in cultured regenerating RGCs. Notably, 8% of naïve RGCs express CXCL12 and transport the chemokine along their axons in the nerve. Thus, axotomy causes its release at the injury site. However, most osteopontin-positive α-RGCs, the main neuronal population that survives optic nerve injury, express CXCR4 instead. Thus, CXCL12-mediated attraction prevents growth-stimulated axons from regenerating distally in the nerve, indicated by axons returning to the lesion site. Accordingly, specific depletion of CXCR4 in RGC reduces aberrant axonal growth and enables long-distance regeneration. Likewise, CXCL12 knockout in RGCs fully mimics these CXCR4−/− effects. Thus, active CXCL12/CXCR4-mediated entrapment of regenerating axons to the injury site contributes to regenerative failure in the optic nerve.
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Reynolds, Andy M., Don R. Reynolds, Sanjay P. Sane, Gao Hu et Jason W. Chapman. « Orientation in high-flying migrant insects in relation to flows : mechanisms and strategies ». Philosophical Transactions of the Royal Society B : Biological Sciences 371, no 1704 (26 septembre 2016) : 20150392. http://dx.doi.org/10.1098/rstb.2015.0392.
Texte intégralRésumé :
High-flying insect migrants have been shown to display sophisticated flight orientations that can, for example, maximize distance travelled by exploiting tailwinds, and reduce drift from seasonally optimal directions. Here, we provide a comprehensive overview of the theoretical and empirical evidence for the mechanisms underlying the selection and maintenance of the observed flight headings, and the detection of wind direction and speed, for insects flying hundreds of metres above the ground. Different mechanisms may be used—visual perception of the apparent ground movement or mechanosensory cues maintained by intrinsic features of the wind—depending on circumstances (e.g. day or night migrations). In addition to putative turbulence-induced velocity, acceleration and temperature cues, we present a new mathematical analysis which shows that ‘jerks’ (the time-derivative of accelerations) can provide indicators of wind direction at altitude. The adaptive benefits of the different orientation strategies are briefly discussed, and we place these new findings for insects within a wider context by comparisons with the latest research on other flying and swimming organisms. This article is part of the themed issue ‘Moving in a moving medium: new perspectives on flight’.
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Min, Jiyoung, Ryulri Kim et Haemin Jeon. « Performance Evaluation of Displacement Measurement System with Marker and Fixed Vision Sensor on Port Structures ». Korea Society of Coastal Disaster Prevention 10, no 1 (30 janvier 2023) : 13–23. http://dx.doi.org/10.20481/kscdp.2023.10.1.13.
Texte intégralRésumé :
This study focused on the measurement of displacement on port structures with the combination of a marker and a vision sensor installed on the fixed location. The proposed algorithm optimizes the intrinsic parameters of the vision sensor using genetic algorithm and then measures the 6-DOF displacement automatically tracking feature points on the marker extracted through the image process. Experimental studies were carried out by using a general IP camera and a marker including 12 feature points. The distance between the camera and the marker was 10 m. Several types of displacements were induced with the precise motion stage, and the results showed that the measurement errors might be reasonable less than 3.5% in rotation and 4.0% in translation. This system was applied on the lock gate located in Incheon port, which corresponds to Type 1 facilities in Korea. The same camera was fixed at 24 m from the marker and the marker was moved by controlling the precise motion stage. The errors of measurements were less than 1 mm and 0.5 degrees, which were precise and accurate enough to evaluate the displacement in the field considering the present evaluation standard for drift, settlement, and slope on port facilities.
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Middleton, Justin, Daniel Stover et Tsonwin Hai. « Chemotherapy-Exacerbated Breast Cancer Metastasis : A Paradox Explainable by Dysregulated Adaptive-Response ». International Journal of Molecular Sciences 19, no 11 (26 octobre 2018) : 3333. http://dx.doi.org/10.3390/ijms19113333.
Texte intégralRésumé :
An emerging picture in cancer biology is that, paradoxically, chemotherapy can actively induce changes that favor cancer progression. These pro-cancer changes can be either inside (intrinsic) or outside (extrinsic) the cancer cells. In this review, we will discuss the extrinsic pro-cancer effect of chemotherapy; that is, the effect of chemotherapy on the non-cancer host cells to promote cancer progression. We will focus on metastasis, and will first discuss recent data from mouse models of breast cancer. Despite reducing the size of primary tumors, chemotherapy changes the tumor microenvironment, resulting in an increased escape of cancer cells into the blood stream. Furthermore, chemotherapry changes the tissue microenvironment at the distant sites, making it more hospitable to cancer cells upon their arrival. We will then discuss the idea and evidence that these devastating pro-metastatic effects of chemotherapy can be explained in the context of adaptive-response. At the end, we will discuss the potential relevance of these mouse data to human breast cancer and their implication on chemotherapy in the clinic.
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Ganti, Vamsi, Michael P. Lamb et Austin J. Chadwick. « Autogenic Erosional Surfaces in Fluvio-deltaic Stratigraphy from Floods, Avulsions, and Backwater Hydrodynamics ». Journal of Sedimentary Research 89, no 8 (27 août 2019) : 815–32. http://dx.doi.org/10.2110/jsr.2019.40.
Texte intégralRésumé :
Abstract Erosional surfaces set the architecture of fluvio-deltaic stratigraphy, and they have classically been interpreted in terms of changes in boundary conditions such as climate, tectonics, and base level (allogenic forces). Intrinsic dynamics of sedimentary systems (autogenic dynamics) can also create a rich stratigraphic architecture, and a major knowledge gap exists in parsing the relative roles of autogenic versus allogenic processes. Emerging theoretical and experimental work suggests that backwater hydrodynamics play an important role in driving transient channel incision in river deltas, even those experiencing net aggradation. Here, we identify and quantify two autogenic mechanisms that produce broad erosional surfaces in fluvio-deltaic stratigraphy, namely, floods and avulsions. Using a simple mass-balance model for single-threaded delta channel systems, we show that flood-induced scours begin near the shoreline, and avulsion-induced scours begin at the avulsion site, and both propagate upstream over a distance that scales with the backwater length, bed slope, and bed grain size. We also develop scaling relationships for the maximum scour depths arising from these mechanisms, which are functions of characteristic flow depth and formative flood variability. We test our theoretical predictions using a flume experiment of river delta evolution governed by persistent backwater hydrodynamics under constant relative sea level. Results indicate that autogenic dynamics of backwater-mediated deltas under conditions of constant base level can result in stratigraphic surfaces and shoreline trajectories similar to those often interpreted to represent multiple sea-level cycles. Our work provides a quantitative framework to decouple autogenic and allogenic controls on erosional surfaces preserved in fluvio-deltaic stratigraphy.
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Liu, Haibo, Jiaqian Wang, Yonglin He, Wenwen Zhang, Lei Lei, Long Chen, Yalan Chen, Jing Zhu, Juncai Tu et Kun Li. « Investigation of the binding properties of 3,4-dihydroxybenzaldehyde from Salvia miltiorrhiza (Bunge) with human serum albumin via multi-spectroscopic and molecular docking techniques ». BioResources 17, no 2 (25 mars 2022) : 2680–95. http://dx.doi.org/10.15376/biores.17.2.2680-2695.
Texte intégralRésumé :
To investigate the binding properties of 3,4-dihydroxybenzaldehyde with human serum albumin, as well as the structural changes of human serum albumin under a simulated physiological pH value (a pH of 7.4) and a high 3,4-dihydroxybenzaldehyde concentration, a series of techniques, i.e., fluorescence, synchronous fluorescence, ultraviolet-visible absorption, Fourier-transform infrared spectroscopy, and molecular docking simulation, were employed. Steady state fluorescence showed that 3,4-dihydroxybenzaldehyde quenched the intrinsic fluorescence of human serum albumin via a static mechanism. The 3,4-dihydroxybenzaldehyde-human serum albumin complex had a strong affinity (Kb = 105 M-1) at various temperatures. It was shown that 3,4-dihydroxybenzaldehyde was bound to the IB subdomain of human serum albumin primarily via hydrogen bonding and van der Waals forces at high 3,4-dihydroxybenzaldehyde concentrations, based on the results of the thermodynamic and molecular docking. Furthermore, the fluorescence emission spectrum and Fourier-transform infrared spectroscopy results indicated that the binding distance between 3,4-dihydroxybenzaldehyde and human serum albumin was 4.42 nm. In addition, 3,4-dihydroxybenzaldehyde induced conformational changes of human serum albumin. These findings provide reasonable evidence for further understanding the distribution of 3,4-dihydroxybenzaldehyde when it spreads into human blood serum, which may be helpful in food and medicine research.
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Gu, Jiajia, Li Yin, Jing Wu, Nan Zhang, Teng Huang, Kai Ding, Haixia Cao, Lin Xu et Xia He. « Cetuximab and Cisplatin Show Different Combination Effect in Nasopharyngeal Carcinoma Cells Lines via Inactivation of EGFR/AKT Signaling Pathway ». Biochemistry Research International 2016 (2016) : 1–10. http://dx.doi.org/10.1155/2016/7016907.
Texte intégralRésumé :
Nasopharyngeal carcinoma (NPC) is a common malignant cancer in South China. Cisplatin is a classical chemotherapeutic employed for NPC treatment. Despite the use of cisplatin-based concurrent chemoradiotherapy, distant failure still confuses clinicians and the outcome of metastatic NPC remains disappointing. Hence, a potent systemic therapy is needed for this cancer. Epidermal growth factor receptor (EGFR) represents a promising new therapeutic target in cancer. We predicted that combining the conventional cytotoxic drug cisplatin with the novel molecular-targeted agent cetuximab demonstrates a strong antitumor effect on NPC cells. In this study, we selected HNE1 and CNE2 cells, which have been proved to possess different EGFR expression levels, to validate our conjecture. The two-drug regimen showed a significant synergistic effect in HNE1 cells but an additive effect in CNE2 cells. Our results showed that cisplatin-induced apoptosis was significantly enhanced by cetuximab in the high EGFR-expressing HNE1 cells but not in CNE2 cells. Further molecular mechanism study indicated that the EGFR/AKT pathway may play an important role in cell apoptosis via the mitochondrial-mediated intrinsic pathway and lead to the different antitumor effects of this two-drug regimen between HNE1 and CNE2 cells. Thus, the regimen may be applied in personalized NPC treatments.
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Henry, L. A., J. Moreno Navas et J. M. Roberts. « Multi-scale interactions between local hydrography, seabed topography, and community assembly on cold-water coral reefs ». Biogeosciences Discussions 9, no 12 (12 décembre 2012) : 17885–912. http://dx.doi.org/10.5194/bgd-9-17885-2012.
Texte intégralRésumé :
Abstract. We investigated how the interactive effects of hydrography, topography and intrinsic community dynamics influence the assembly of species and functional traits across multiple spatial scales of a cold-water coral reef seascape. In a novel approach for these ecosystems, we use a spatially resolved complex three-dimensional flow model of hydrography to help explain assembly patterns. Forward selection of distance-based Moran's eigenvector mapping (dbMEM) variables identified two submodels of spatial scales at which communities are structured: broad-scale (across reef) and fine-scale (within reef). Canonical variance partitioning revealed broad-scale structures created mainly by variability in bathymetry and hydrography across reefs, which manifest as relatively narrow environmental niches for predators and scavenging detritivores. Fine-scale assembly was related more to processes that create spatially autocorrelated patches of fauna within a reef due to restricted dispersal in sessile fauna but social mating interactions and food supply in more mobile organisms. Our study implies that perturbations such as habitat fragmentation and altered hydrodynamic regimes have the potential to induce significant changes in the structure and function of cold-water coral reef ecosystems at spatial scales that span the entire seascape.
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Zhou, Zitao, Jino Son, Bryan Harper, Zheng Zhou et Stacey Harper. « Influence of surface chemical properties on the toxicity of engineered zinc oxide nanoparticles to embryonic zebrafish ». Beilstein Journal of Nanotechnology 6 (20 juillet 2015) : 1568–79. http://dx.doi.org/10.3762/bjnano.6.160.
Texte intégralRésumé :
Zinc oxide nanoparticles (ZnO NPs) are widely used in a variety of products, thus understanding their health and environmental impacts is necessary to appropriately manage their risks. To keep pace with the rapid increase in products utilizing engineered ZnO NPs, rapid in silico toxicity test methods based on knowledge of comprehensive in vivo and in vitro toxic responses are beneficial in determining potential nanoparticle impacts. To achieve or enhance their desired function, chemical modifications are often performed on the NPs surface; however, the roles of these alterations play in determining the toxicity of ZnO NPs are still not well understood. As such, we investigated the toxicity of 17 diverse ZnO NPs varying in both size and surface chemistry to developing zebrafish (exposure concentrations ranging from 0.016 to 250 mg/L). Despite assessing a suite of 19 different developmental, behavioural and morphological endpoints in addition to mortality in this study, mortality was the most common endpoint observed for all of the ZnO NP types tested. ZnO NPs with surface chemical modification, regardless of the type, resulted in mortality at 24 hours post-fertilization (hpf) while uncoated particles did not induce significant mortality until 120 hpf. Using eight intrinsic chemical properties that relate to the outermost surface chemistry of the engineered ZnO nanoparticles, the highly dimensional toxicity data were converted to a 2-dimensional data set through principal component analysis (PCA). Euclidean distance was used to partition different NPs into several groups based on converted data (score) which were directly related to changes in the outermost surface chemistry. Kriging estimations were then used to develop a contour map based on mortality data as a response. This study illustrates how the intrinsic properties of NPs, including surface chemical modifications and capping agents, are useful to separate and identify ZnO NP toxicity to zebrafish (Danio rerio).
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Tolaney, Sara M., Hao Guo, Sonia Pernas, William T. Barry, Deborah A. Dillon, Lauren Ritterhouse, Bryan P. Schneider et al. « Seven-Year Follow-Up Analysis of Adjuvant Paclitaxel and Trastuzumab Trial for Node-Negative, Human Epidermal Growth Factor Receptor 2–Positive Breast Cancer ». Journal of Clinical Oncology 37, no 22 (1 août 2019) : 1868–75. http://dx.doi.org/10.1200/jco.19.00066.
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PURPOSE The Adjuvant Paclitaxel and Trastuzumab trial was designed to address treatment of patients with small human epidermal growth factor receptor 2 (HER2)–positive breast cancer. The primary analysis of the Adjuvant Paclitaxel and Trastuzumab trial demonstrated a 3-year disease-free survival (DFS) of 98.7%. In this planned secondary analysis, we report longer-term outcomes and exploratory results to characterize the biology of small HER2-positive tumors and genetic factors that may predispose to paclitaxel-induced peripheral neuropathy (TIPN). PATIENTS AND METHODS In this phase II study, patients with HER2-positive breast cancer with tumors 3 cm or smaller and negative nodes received paclitaxel (80 mg/m2) with trastuzumab for 12 weeks, followed by trastuzumab for 9 months. The primary end point was DFS. Recurrence-free interval (RFI), breast cancer–specific survival, and overall survival (OS) were also analyzed. In an exploratory analysis, intrinsic subtyping by PAM50 (Prosigna) and calculation of the risk of recurrence score were performed on the nCounter analysis system on archival tissue. Genotyping was performed to investigate TIPN. RESULTS A total of 410 patients were enrolled from October 2007 to September 2010. After a median follow-up of 6.5 years, there were 23 DFS events. The 7-year DFS was 93% (95% CI, 90.4 to 96.2) with four (1.0%) distant recurrences, 7-year OS was 95% (95% CI, 92.4 to 97.7), and 7-year RFI was 97.5% (95% CI, 95.9 to 99.1). PAM50 analyses (n = 278) showed that most tumors were HER2-enriched (66%), followed by luminal B (14%), luminal A (13%), and basal-like (8%). Genotyping (n = 230) identified one single-nucleotide polymorphism, rs3012437, associated with an increased risk of TIPN in patients with grade 2 or greater TIPN (10.4%). CONCLUSION With longer follow-up, adjuvant paclitaxel and trastuzumab is associated with excellent long-term outcomes. Distribution of PAM50 intrinsic subtypes in small HER2-positive tumors is similar to that previously reported for larger tumors.
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Boettcher, Shannon W. « (Invited) Cooperative Fe Sites on Transition Metal (Oxy)Hydroxides for High Oxygen Evolution Activity ». ECS Meeting Abstracts MA2022-01, no 23 (7 juillet 2022) : 1167. http://dx.doi.org/10.1149/ma2022-01231167mtgabs.
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Heterogeneous electrocatalysts for the oxygen evolution reaction (OER) are complicated materials with dynamic structures. They exhibit potential-induced phase transitions, potential-dependent electronic properties, variable oxidation and protonation states, and disordered local/surface phases. These properties make understanding the OER, and ultimately designing higher-efficiency catalysts, challenging. Measurements of intrinsic activity show that, by far, the most-active phases for OER under alkaline conditions are Fe-containing mixed-metal oxyhydroxides, but exactly how they function remains controversial. I will discuss our work to understand the key properties of these catalysts, including morphology, composition, and molecular/electronic structure, and how they evolve and are dynamic under active catalytic conditions. Specifically, I will highlight new work where we have been able to systematically control the concentration of surface Fe species on NiOOH and CoOOH host structures. We discover that the per-Fe turn-over frequency (TOFFe) for the OER increases nearly linearly with the Fe concentration, providing clear evidence for cooperative effects between Fe atoms and suggestive of a mechanism involving multiple Fe sites that is supported by density functional theory calculations. In sum, these concepts inform design strategies for higher-performance catalyst architectures and for their incorporation into practical electrolyzer devices to make clean hydrogen fuel from inexpensive renewable electricity for green long-distance transportation and long-duration energy storage.
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Roman-Lopes, A. « A New Galactic Wolf-Rayet Star in Centaurus ». ISRN Astronomy and Astrophysics 2011 (14 septembre 2011) : 1–6. http://dx.doi.org/10.5402/2011/632850.
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I communicate the detection of a new Galactic Wolf-Rayet star (WR60a) in Centaurus. The H- and K-band spectra of WR60a show strong carbon near-infrared emission lines, characteristic of Wolf-Rayet stars of the WC5-7 subtype. Adopting mean absolute magnitude MK and mean intrinsic (J-KS) and (H-KS) colours, it was found that WR60a suffers a mean visual extinction of 3.8±1.3 magnitudes, being located at a probable heliocentric distance of 5.2±0.8 Kpc, which for the related Galactic longitude (l=312) puts this star probably in the Carina-Sagittarius arm at about 5.9 kpc from the Galactic center. I searched for clusters in the vicinity of WR60a and in principle found no previously known clusters in a search radius region of several tens arcminutes. The detection of a well-isolated WR star induced us to seek for some still unknown cluster, somewhere in the vicinity of WR60a. From inspection of 5.8 μm and 8.0 μm Spitzer/IRAC GLIMPSE images of the region around the new WR star, strong mid-infrared extended emission at about 13.5 arcmin south-west of WR60a was found. The study of the H-KS colour distribution of point sources associated with the extended emission reveals the presence of a new Galactic cluster candidate probably formed by at least 85 stars.
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Lee, Cheng-Sheng, Ruoxi W. Wang, Hsiao-Han Chang, Daniel Capurso, Mark R. Segal et James E. Haber. « Chromosome position determines the success of double-strand break repair ». Proceedings of the National Academy of Sciences 113, no 2 (29 décembre 2015) : E146—E154. http://dx.doi.org/10.1073/pnas.1523660113.
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Repair of a chromosomal double-strand break (DSB) by gene conversion depends on the ability of the broken ends to encounter a donor sequence. To understand how chromosomal location of a target sequence affects DSB repair, we took advantage of genome-wide Hi-C analysis of yeast chromosomes to create a series of strains in which an induced site-specific DSB in budding yeast is repaired by a 2-kb donor sequence inserted at different locations. The efficiency of repair, measured by cell viability or competition between each donor and a reference site, showed a strong correlation (r = 0.85 and 0.79) with the contact frequencies of each donor with the DSB repair site. Repair efficiency depends on the distance between donor and recipient rather than any intrinsic limitation of a particular donor site. These results further demonstrate that the search for homology is the rate-limiting step in DSB repair and suggest that cells often fail to repair a DSB because they cannot locate a donor before other, apparently lethal, processes arise. The repair efficiency of a donor locus can be improved by four factors: slower 5′ to 3′ resection of the DSB ends, increased abundance of replication protein factor A (RPA), longer shared homology, or presence of a recombination enhancer element adjacent to a donor.