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Lower levels of glucocorticoids in crop-raiders: diet quality as a potential `pacifier' against stress in free-ranging Asian elephants in a human-production habitat
No full textOverlapping habitats and sharing of resources between elephants and people has led to intense elephant-human conflicts, especially crop depredation by elephants, across elephant-range countries. While raiding agricultural crops, elephants face numerous threats from people through chase, injury and the risk of death which could enhance the associated energetic costs, ultimately elevating their stress levels. We hypothesized that crop-raiders (in the human-production habitat) would show higher faecal glucocorticoid metabolite (fGCM) levels, a proxy of stress-response, as compared to nonraiders (in protected forests). To study this, 208 faecal samples were collected from crop-raiding elephants in a human-production habitat and 394 samples from nonraiding elephants in protected forests during 2013 and 2015. Contrary to our expectation, fGCM levels were significantly higher in nonraiding than in crop-raiding elephants of both sexes. As one of the possible factors for lower fGCM in elephants inhabiting the human-production habitat, the influence of benefits obtained from foraging here was assessed. For this, the difference in vegetation greenness (standing biomass) between the human-production habitat and the protected forests was analysed from remotely-sensed Normalized Differential Vegetation Index (NDVI), and further confirmed by measuring dietary quality (faecal nitrogen (N) content and C:N ratio as proxies for crude protein). Interestingly, higher NDVI values (greater biomass availability), higher N content and lower faecal C:N ratio (indicating higher protein content in the diet) of elephants in the human-production habitat suggested enhanced nutritional levels here as compared to protected forests. Further, there were significant correlations between faecal C:N ratio (positive) or N content (negative) and fGCM levels. These findings suggest that crop-raiding comes with the benefits of a superior quality diet which may help in reducing human-induced stress-response in elephants inhabiting or foraging within human-production habitats
Performance and Reliability Insights of Drain Extended FinFET Devices for High Voltage SoC Applications
No full textIn this paper1, Drain extended FinFET device design and the challenges associated with the performance and reliability are discussed. Physical insights into the performance vs. reliability trade-off for the Fin enabled high voltage designs is elaborated and compared with their planar counterpart (DeMOS). Effect of Fin width discretization over ESD reliability, Safe Operating Area and HCI reliability are discussed
Modified Interface Properties of Au/n-type GaN Schottky Junction with a High-k Ba0.6Sr0.4TiO3 Insulating Layer
No full textThe interface properties of a Au/n-GaN Schottky junction (SJ) were modified by placing a high-k barium strontium titanate (Ba0.6Sr0.4TiO3) insulating layer between the Au and n-GaN semiconductor. The surface morphology, chemical composition, and electrical properties of Au/Ba0.6Sr0.4TiO3 (BST)/n-GaN metal/insulator/semiconductor (MIS) junctions were explored by atomic force microscopy, energy-dispersive x-ray spectroscopy, current-voltage (I-V) and capacitance-voltage (C-V) techniques. The electrical results of the MIS junction are correlated with the SJ and discussed further. The MIS junction exhibited an exquisite rectifying nature compared to the SJ. An average barrier height (BH) and ideality factors were extracted to be 0.77eV, 1.62eV and 0.92eV, 1.95 for the SJ and MIS junction, respectively. The barrier was raised by 150meV for the MIS junction compared to the MS junction, implying that the BH was effectively altered by the BST insulating layer. The BH values extracted by I-V, Cheung's and Norde functions were nearly equal to one another, indicating that the techniques applied here were dependable and suitable. The frequency-dependent properties of the SJ and MIS junction were explored and discussed. It was found that the interface state density of the MIS junction was smaller than the SJ. This implies that the BST layer plays an imperative role in the decreased N-SS. Poole-Frenkel emission was the prevailed current conduction mechanism in the reverse-bias of both the SJ and MIS junction
Toward a Universal Structural and Energetic Model for Prokaryotic Promoters
No full textWith almost no consensus promoter sequence in prokaryotes, recruitment of RNA polymerase (RNAP) to precise transcriptional start sites (TSSs) has remained an unsolved puzzle. Uncovering the underlying mechanism is critical for understanding the principle of gene regulation. We attempted to search the hidden code in -16,500 promoters of 12 prokaryotes representing two kingdoms in their structure and energetics. Twenty-eight fundamental parameters of DNA structure including backbone angles, basepair axis, and interbasepair and intrabasepair parameters were used, and information was extracted from x-ray crystallography data. Three parameters (solvation energy, hydrogen-bond energy, and stacking energy) were selected for creating energetics profiles using in-house programs. DNA of promoter regions was found to be inherently designed to undergo a change in every parameter undertaken for the study, in all prokaryotes. The change starts from some distance upstream of TSSs and continues past some distance from TSS, hence giving a signature state to promoter regions. These signature states might be the universal hidden codes recognized by RNAP. This observation was reiterated when randomly selected promoter sequences (with little sequence conservation) were subjected to structure generation; all developed into very similar three-dimensional structures quite distinct from those of conventional B-DNA and coding sequences. Fine structural details at important motifs (viz. -11, -35, and -75 positions relative to TSS) of promoters reveal novel to our knowledge and pointed insights for RNAP interaction at these locations; it could be correlated with how some particular structural changes at the -11 region may allow insertion of RNAP amino acids in interbasepair space as well as facilitate the flipping out of bases from the DNA duplex
Manufacturing of high strength aluminium composites reinforced with nano tungsten particles for electrical application and investigation on in-situ reaction during processing
No full textThe improvement of strength without compromising the conductivity remains a major issue in developing superior aluminium conductors. This could be addressed by dispersion of nano-sized high melting point elements such as tungsten which has limited solid-solubility in the aluminium matrix. The composites fabricated in this study shows 1.3 times improvement in yield strength, and 2 times increase in UTS. The composites also exhibit superior electrical conductivity compared to other aluminium alloys. Solid-state processing technique was adopted for composite fabrication to avoid thermally activated reaction, between matrix and particles. An unexpected result was the observation of mechanical energy induced interface reaction between aluminum and tungsten during the processing which was not expected at the low processing temperatures. This was confirmed by detailed TEM examination that probed the formation and structure of this new phase. These findings open up newer possibilities toward efficient and scalable manufacturing of high conductive composites with improved strength. (C) 2018 Published by Elsevier B.V
WASPnest: a worldwide assessment of social Polistine nesting behavior
No full textCooperative breeding decreases the direct reproductive output of subordinate individuals, but cooperation can be evolutionarily favored when there are challenges or constraints to breeding independently. Environmental factors, including temperature, precipitation, latitude, high seasonality, and environmental harshness have been hypothesized to correlate with the presence of cooperative breeding. However, to test the relationship between cooperation and ecological constraints requires comparative data on the frequency and variation of cooperative breeding across differing environments, ideally replicated across multiple species. Paper wasps are primitively social species, forming colonies composed of reproductively active dominants and foraging subordinates. Adult female wasps, referred to as foundresses, initiate new colonies. Nests can be formed by a single solitary foundress (noncooperative) or by multiple foundress associations (cooperative). Cooperative behavior varies within and among species, making paper wasps species well suited to disentangling ecological correlates of variation in cooperative behavior. This data set reports the frequency and extent of cooperative nest founding for 87 paper wasp species. Data were assembled from more than 170 published sources, previously unpublished field observations, and photographs contributed by citizen scientists to online natural history repositories. The data set includes 25,872 nest observations and reports the cooperative behavioral decisions for 45,297 foundresses. Species names were updated to reflect modern taxonomic revisions. The type of substrate on which the nest was built is also included, when available. A smaller population-level version of this data set found that the presence or absence of cooperative nesting in paper wasps was correlated with temperature stability and environmental harshness, but these variables did not predict the extent of cooperation within species. This expanded data set contains details about individual nests and further increases the power to address the relationship between the environment and the presence and extent of cooperative breeding. Beyond the ecological drivers of cooperation, these high-resolution data will be useful for future studies examining the evolutionary consequences of variation in social behavior. This data set may be used for research or educational purposes provided that this data paper is cited
Detection of the Galactic warm neutral medium in HI 21-cm absorption
No full textWe report a deep Giant Metrewave Radio Telescope search for Galactic HI 21-cm absorption towards the quasar B0438-436, yielding the detection of wide, weak HI21-cm absorption, with a velocity-integrated HI 21-cm optical depth of 0.0188 +/- 0.0036 km s(-1). Comparing this with the HI column density measured in the Parkes Galactic All-Sky Survey gives a column density weighted harmonic mean spin temperature of 3760 +/- 365 K, one of the highest measured in the Galaxy. This is consistent with most of the HI along the sightline arising in the stable warm neutral medium. The low-peak HI 21-cm optical depth towards B0438-436 implies negligible self-absorption, allowing a multi-Gaussian joint decomposition of the HI 21-cm absorption and emission spectra. This yields a gas kinetic temperature of T-k <= (4910 +/- < t > 1900) K, and a spin temperature of T-s = (1000 +/- 345) K for the gas that gives rise to the HI21-cm absorption. Our data are consistent with the HI 21-cm absorption arising from either the stable WNM, with T-s << T-K, T-k approximate to 5000 K, and little penetration of the background Lyman-alpha radiation field into the neutral hydrogen, or the unstable neutral medium, with T-s approximate to T-k approximate to 1000 K
SPEECH ENHANCEMENT USING MULTIPLE DEEP NEURAL NETWORKS
No full textIn this work, we present a variant of multiple deep neural network (DNN) based speech enhancement method. We directly estimate clean speech spectrum as a weighted average of outputs from multiple DNNs. The weights are provided by a gating network. The multiple DNNs and the gating network are trained jointly. The objective function is set as the mean square logarithmic error between the target clean spectrum and the estimated spectrum. We conduct experiments using two and four DNNs using the TIMIT corpus with nine noise types (four seen noises and five unseen noises) taken from the AURORA database at four different signal-to-noise ratios (SNRs). We also compare the proposed method with a single DNN based speech enhancement scheme and existing multiple DNN schemes using segmental SNR, perceptual evaluation of speech quality (PESQ) and short-term objective intelligibility (STOI) as the evaluation metrics. These comparisons show the superiority of proposed method over baseline schemes in both seen and unseen noises. Specifically, we observe an absolute improvement of 0.07 and 0.04 in PESQ measure compared to single DNN when averaged over all noises and SNRs for seen and unseen noise cases respectively
Spatially varying electronic dephasing in three-dimensional topological insulators
No full textInformation processing devices operating in the quantum mechanical regime strongly rely on the quantum coherence of charge carriers. Studies of electronic dephasing in conventionalmetallic and semiconductor systems have not only paved the way toward high coherence quantum electronics, but also led to fundamental new insights in condensed matter physics. In this paper, we perform a spatially resolved study of electronic dephasing in three-dimensional topological insulators by exploiting an edge-versus surface-contacted measurement scheme. Unlike conventional two-dimensional systems that are characterized by a single dephasing mechanism, we find that dephasing in our samples evolves from a variable-range-hopping-type mechanism on the sample surface to a Nyquist-type electron-electron interaction mechanism in the subsurface layers. This is confirmed independently by the temperature and chemical potential dependence of the dephasing length, and gate-dependent suppression/enhancement of the weak antilocalization effect. Our devices are fabricated using bulk insulating topological insulator BiSbTe1.25Se1.75 capped with hexagonal-boron nitride in an inert environment, ruling out any extrinsic effects and confirming the topological surface state origin of our results. Our work addresses the idea of spatially resolved electronic dephasing and coherent transport in perhaps the most important topological insulator discovered so far. Our edge-versus-surface scheme may be applied to dephasing studies in a wide class of 2D materials
The second messenger cyclic di-AMP negatively regulates the expression of Mycobacterium smegmatis recA and attenuates DNA strand exchange through binding to the C-terminal motif of mycobacterial RecA proteins
No full textCyclic di-GMP and cyclic di-AMP are second messengers produced by a wide variety of bacteria. They influence bacterial cell survival, biofilm formation, virulence and bacteria-host interactions. However, many of their cellular targets and biological effects are yet to be determined. A chemical proteomics approach revealed that Mycobacterium smegmatis RecA (MsRecA) possesses a high-affinity cyclic di-AMP binding activity. We further demonstrate that both cyclic di-AMP and cyclic di-GMP bind specifically to the C-terminal motif of MsRecA and Mycobacterium tuberculosis RecA (MtRecA). Escherichia coli RecA (EcRecA) was devoid of cyclic di-AMP binding but have cyclic di-GMP binding activity. Notably, cyclic di-AMP attenuates the DNA strand exchange promoted by MsRecA as well as MtRecA through the disassembly of RecA nucleoprotein filaments. However, the structure and DNA strand exchange activity of EcRecA nucleoprotein filaments remain largely unaffected. Furthermore, M. smegmatis disA cells were found to have undetectable RecA levels due to the translational repression of recA mRNA. Consequently, the Delta disA mutant exhibited enhanced sensitivity to DNA-damaging agents. Altogether, this study points out the importance of sequence diversity among recA genes, the role(s) of cyclic di-AMP and reveals a new mode of negative regulation of recA gene expression, DNA repair and homologous recombination in mycobacteria