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On the signs of Fourier coefficients of Hilbert cusp forms
No full textWe prove that given any ϵ> 0 and a primitive adelic Hilbert cusp form f of weight k= (k1, k2, � , kn) � (2 Z) n and full level, there exists an integral ideal m with N(m)�ϵQf9/20+ϵ such that the m-th Fourier coefficient of Cf(m) of f is negative. Here n is the degree of the associated number field, N(m) is the norm of integral ideal m and Qf is the analytic conductor of f. In the case of arbitrary weights, we show that there is an integral ideal m with N(m)�ϵQf1/2+ϵ such that Cf(m) < 0. We also prove that when k= (k1, k2, � , kn) � (2 Z) n, asymptotically half of the Fourier coefficients are positive while half are negative
Emergence of social inequality in the spatial harvesting of renewable public goods
No full textSpatially extended ecological public goods, such as forests, grasslands, and fish stocks, are at risk of being overexploited by selfish consumers-a phenomenon widely recognized as the 'tragedy of the commons.' The interplay of spatial and ecological dimensions introduces new features absent in non-spatial ecological contexts, such as consumer mobility, local information availability, and strategy evolution through social learning in neighborhoods. It is unclear how these features interact to influence the harvesting and dispersal strategies of consumers. To answer these questions, we develop and analyze an individual-based, spatially structured, eco-evolutionary model with explicit resource dynamics. We report the following findings. (1) When harvesting efficiency is low, consumers evolve a sedentary consumption strategy, through which the resource is harvested sustainably, but with harvesting rates far below their maximum sustainable value. (2) As harvesting efficiency increases, consumers adopt a mobile 'consume-and-disperse' strategy, which is sustainable, equitable, and gives maximum sustainable yield. (3) A further increase in harvesting efficiency leads to large-scale overexploitation. (4) If costs of dispersal are significant, increased harvesting efficiency also leads to social inequality between frugal sedentary consumers and overexploitative mobile consumers. Whereas overexploitation can occur without social inequality, social inequality always leads to overexploitation. Thus, we identify four conditions that-while being characteristic of technological progress in modern societies-risk social inequality and overexploitation: high harvesting efficiency, moderately low costs of dispersal, high consumer density, and the tendency of consumers to adopt new strategies rapidly. We also show how access to global information-another feature widespread in modern societies-helps mitigate these risks
Intravenous immunoglobulin mediates anti-inflammatory effects in peripheral blood mononuclear cells by inducing autophagy
No full textAutophagy plays an important role in the regulation of autoimmune and autoinflammatory responses of the immune cells. Defective autophagy process is associated with various autoimmune and inflammatory diseases. Moreover, in many of these diseases, the therapeutic use of normal immunoglobulin G or intravenous immunoglobulin (IVIG), a pooled normal IgG preparation, is well documented. Therefore, we explored if IVIG immunotherapy exerts therapeutic benefits via induction of autophagy in the immune cells. Here we show that IVIG induces autophagy in peripheral blood mononuclear cells (PBMCs). Further dissection of this process revealed that IVIG-induced autophagy is restricted to inflammatory cells like monocytes, dendritic cells, and M1 macrophages but not in cells associated with Th2 immune response like M2 macrophages. IVIG induces autophagy by activating AMP-dependent protein kinase, beclin-1, class III phosphoinositide 3-kinase and p38 mitogen-activated protein kinase and by inhibiting mammalian target of rapamycin. Mechanistically, IVIG-induced autophagy is F(ab�)2-dependent but sialylation independent, and requires endocytosis of IgG by innate cells. Inhibition of autophagy compromised the ability of IVIG to suppress the inflammatory cytokines in innate immune cells. Moreover, IVIG therapy in inflammatory myopathies such as dermatomyositis, antisynthetase syndrome and immune-mediated necrotizing myopathy induced autophagy in PBMCs and reduced inflammatory cytokines in the circulation, thus validating the translational importance of these results. Our data provide insight on how circulating normal immunoglobulins maintain immune homeostasis and explain in part the mechanism by which IVIG therapy benefits patients with autoimmune and inflammatory diseases. © 2020, The Author(s)
Lower bound limit analysis of unsupported vertical circular excavations in rocks using Hoek-Brown failure criterion
No full textThe stability of vertical unsupported circular excavations in rock media, obeying generalized Hoek-Brown yield criterion, has been investigated by using the lower bound finite elements limit analysis. An axisymmetric analysis, composed of a planar domain with a mesh of three-noded triangular elements, has been carried out. The optimization problem is dealt with by using the semidefinite programming technique avoiding the need of either smoothing the yield surface or making any assumption associated with the circumferential stress (�θ). A detailed parametric study has been executed, and the effects of different input material parameters, namely, geological strength index (GSI), yield parameter (mi), and the disturbance factor (D) on the results have been studied. For different height to radius ratios of the excavation, the computed results are presented in the form of nondimensional stability numbers. Failure mechanisms have also been investigated for a few typical cases. The results from the analysis have been compared with that evaluated separately with the application of the software OptumG2
Review on ultra-high temperature boride ceramics
No full textCeramic materials having melting points higher than 3000 °C and suitable for structural applications at above 2000 °C are commonly known as Ultra-High Temperature Ceramics (UHTCs). Several transition metal di-borides, possessing the desired combinations of thermo-mechanical, physical and chemical properties, form an important sub-class of the UHTCs. Over the last couple of decades, there has been a growing interest for UHTCs in general, and for the transition metal di-borides in particular, due to the increasing demands in hypersonic aerospace vehicles, atmospheric re-entry vehicles and energy applications. However, problems pertaining to sintering, moderate fracture toughness and experimental challenges associated with reliably measuring the elevated temperature properties, as well as the properties that determine the performances at the actual service conditions, have limited their widespread applications. This paper comprehensively reviews the various routes/techniques, including the advanced ones, as adopted for the synthesis and densification of the di-borides. The effects of sinter-additives and reinforcements on the densification, microstructure and various properties, including elevated temperature properties have been discussed in critical terms. Due attention has been paid towards understanding the challenges associated with the experimental measurements of the high temperature properties under extreme environmental conditions and the very recently developed techniques for the same. Some of the existing and futuristic applications of transition metal di-borides have also been discussed. Finally, the review concludes with an outlook towards some of the outstanding issues
Time-frequency analysis for two cases of boundary-layer transition induced by random distributed roughness
No full textAbstract: The boundary layer transition induced by distributed surface roughness has great practical relevance, but remains poorly understood. In this experimental work, we investigate the transition in a flat-plate boundary layer downstream of a localized strip of random distributed roughness. The boundary layer exhibits different temporal and spectral behaviour in two (roughness-) Reynolds-number regimes separated by a critical value. In the �sub-critical� regime, the velocity signals show presence of �turbulent spots�, whereas in the �super-critical� regime, no distinct turbulent spots are observed. Two boundary-layer profiles, one each from the sub-critical and super-critical regimes, are chosen for comparison. The sub-critical case exhibits a bi-modal power spectrum having two humps in frequency ranges differing by an order of magnitude, whereas the super-critical case has a uni-modal spectrum with a single hump in the high-frequency range. The wavelet analysis shows that the energy distribution is intermittent in time for both the cases at all frequencies. However, for the sub-critical case, the energy in the high-frequency range appears as clusters, which are seen as turbulent spots in the velocity signal. On the other hand, for the super-critical case there is no such clustering, consistent with the absence of spots in the velocity signal. We conjecture that, for the sub-critical case, the motions corresponding to the low-frequency spectral hump (possibly the streamwise streaks) could be responsible for imparting organization to the high-frequency motions in the form of turbulent spots. We also detect �events� in the wavelet-energy time series. For the sub-critical case, the events in the high-frequency range have a higher degree of time-localization, which increases with frequency. For the super-critical case, however, the time-localization is independent of frequency over nearly the entire frequency range. These findings present two different scenarios for the late stages of transition, having distinct time-frequency behaviour. This could have implications towards modelling roughness-induced transition.
Influence of low energy Ag ion irradiation for formation of Bi2Se3 phase from Bi/GeSe2 heterostructure thin films
No full textThe manuscript reports on the influence of 40 keV Ag �ve ion bombardment with different fluences on the microstructural and optical properties of thermally evaporated Bi/GeSe2 bilayer thin films. Two different fluences (5 � 1014 ions cm�2 and 1 � 1015 ions cm�2) of Ag �ve ions were used to irradiate the thin films that changed the microstructure and optical properties as studied by different spectroscopic methods like X-ray diffraction method (XRD), Energy dispersive X-ray spectroscopy (EDS), Field emission scanning electron microscopy (FESEM), Atomic force microscopy (AFM), Raman spectroscopy, and UV�Vis spectroscopy. The evolution of topological Bi2Se3 phase occurs after ion irradiated diffusion of Bi into GeSe2 matrix. The optical parameters as calculated from the transmission spectra infers the indirect allowed transition with reduction of Eg on ion irradiation. The various optical parameters like absorption coefficient (α), optical energy gap (Eg), Tauc parameter (B1/2), Urbach energy (Ee), extinction coefficient (k), refractive index (n) were modified with ion irradiation. The surface morphology is being changed after irradiation as probed by AFM and FESEM. The Raman spectra support the formation of Bi2Se3 phase with irradiation. The obtained results have been explained on the basis of increase in band tailing of valence band due to defect states caused by the irradiation. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature
Degeneracy in the emergence of spike-triggered average of hippocampal pyramidal neurons
No full textHippocampal pyramidal neurons are endowed with signature excitability characteristics, exhibit theta-frequency selectivity � manifesting as impedance resonance and as a band-pass structure in the spike-triggered average (STA) � and coincidence detection tuned for gamma-frequency inputs. Are there specific constraints on molecular-scale (ion channel) properties in the concomitant emergence of cellular-scale encoding (feature detection and selectivity) and excitability characteristics? Here, we employed a biophysically-constrained unbiased stochastic search strategy involving thousands of conductance-based models, spanning 11 active ion channels, to assess the concomitant emergence of 14 different electrophysiological measurements. Despite the strong biophysical and physiological constraints, we found models that were similar in terms of their spectral selectivity, operating mode along the integrator-coincidence detection continuum and intrinsic excitability characteristics. The parametric combinations that resulted in these functionally similar models were non-unique with weak pair-wise correlations. Employing virtual knockout of individual ion channels in these functionally similar models, we found a many-to-many relationship between channels and physiological characteristics to mediate this degeneracy, and predicted a dominant role for HCN and transient potassium channels in regulating hippocampal neuronal STA. Our analyses reveals the expression of degeneracy, that results from synergistic interactions among disparate channel components, in the concomitant emergence of neuronal excitability and encoding characteristics
A simple method to extract zeros of certain Eisenstein series of small level
No full textThis paper provides a simple method to extract the zeros of some weight two Eisenstein series of level N where N= 2 , 3 , 5 and 7. The method is based on the observation that these Eisenstein series are integral over the graded algebra of modular forms on SL(2, Z) and their zeros are �controlled� by those of E4 and E6 in the fundamental domain of � (N)
A non-enzymatic urea sensor based on the nickel sulfide / graphene oxide modified glassy carbon electrode
No full textHere, a non-enzymatic graphene stabilized nickel sulphide is used for electrochemical based device for detecting urea is carried out. NiS was used as electron distribution on the compound helps in selective interaction with analytes. However, since neat NiS is unstable during the interaction, stabilization of the compound is very critical. Hence, nickel sulfide/graphene oxide (NiS/GO) was synthesized via the superficial hydrothermal method. The synthesized functionalized GO nanoparticles were characterized for size, surface area, and morphology for tuning to the specific application. This compound nickel sulfide/graphene oxide was used to modify glassy carbon electrode (NiS/GO/MGCE). Detection capabilities of this modified electrode to urea in water was evaluated in both electrochemical and electrochemical impedance spectroscopy (EIS) modes. Results suggests that the NiS/GO nanocomposite modified electrode exhibited a very low limit of detection and the electrode process was identified to be diffusion-controlled. In addition, selectivity, interference, long-term stability and practical applicability of the developed sensor were evaluated. Hence, the developed NiS/GO/MGCE displayed excellent electrocatalytic behaviour towards the sensing of urea with good sensitivity, selectivity, and reproducibility