50175 research outputs found
Sort by
Biophysical quantification of biodiversity and ecosystems services of forest ecosystems in the Western Ghats: a case study of Uttara Kannada District, India
No full textBiodiversity and ecosystem services play key roles in future economic strategies seeking to promote development and prosperity. This study assesses the status of biodiversity and flow of ecosystem services from selected forest types in the Western Ghats. At the sampling sites, the number of tree species ranged from 16 to 79 per hectare depending on the forest type. The estimates for Shannon-Wiener index for trees in the evergreen, moist deciduous and dry deciduous forest plots were 3.02, 2.9 and 1.54, respectively. The total biomass carbon stocks in evergreen, moist deciduous and dry deciduous forests in the study area was 229, 221 and 189 t C/ha, respectively. Analysis of dependency patterns of local communities on forest resources indicated a high dependency on provisional services such as fuelwood, manure and fodder. The study records the highest dependency rates for fuelwood, ranging between 72 and 100% for the three forest types and indicates that forest ecosystems underpin the well-being of the population dependent directly and indirectly on them
Factors influencing the coupling between non-180 degrees domain switching and lattice strain in perovskite piezoceramics
No full textDomain switching and lattice strain are known to be important processes contributing to the large electromechanical response observed in perovskite-based piezoelectrics. However, there is a lack of clarity regarding the coupling between the two phenomena, and the factors which influence this coupling. Here, we report a systematic investigation to understand the factors influencing the coupling between domain switching and lattice strain in perovskite piezoelectrics by x-ray diffraction in situ with electric field. In a slight departure from the conventional approach, we employ a strategy which enables x-ray diffraction study in situ with electric field on randomly oriented piezoelectric grains in their unclamped (free) state. Experiments were carried out on two different systems (1-x)PbTiO3-(x)BiScO3 and (1-x)PbTiO3-(x)PbZrO3 in their rhombohedral phase. We found that lattice strain along the nonpolar < 100 >(R) rhombohedral direction varies linearly with the non-180 degrees domain switching fraction (eta(111)). We introduce a parameter beta to characterize the strength of coupling between the two phenomena and show that the coupling is enhanced when the system approaches the morphotropic phase boundary. We also demonstrate that the grain-to-grain interaction nearly doubles this coupling in a dense piezoelectric ceramic
Mitochondria-localizing BODIPY-copper(II) conjugates for cellular imaging and photo-activated cytotoxicity forming singlet oxygen
No full textCopper(ii) acetylacetonates of N,N,N-donor dipicolylamine (dpa) ligands, viz. Cu(L-1)(acac)]ClO4 (1), Cu(L-2)(acac)]ClO4 (2) and Cu(L-3)(acac)]ClO4 (3), where L-1 is benzyldipicolylamine (bzdpa), L-2 and L-3 are non-iodinated and diiodinated BODIPY (borondipyrromethene) ligands and Hacac is acetylacetone, were synthesized and characterized and their photocytotoxicity was studied. The BODIPY complex 2, structurally characterized by X-ray crystallography, has copper(ii) in a distorted square-pyramidal geometry (degree of trigonality, (5) = 0.28). The one-electron paramagnetic and redox active copper(ii) complexes displayed 1:1 electrolytic behaviour in polar organic solvents. The BODIPY complexes 2 and 3 showed respective visible bands at 498 and 539 nm in 5% DMSO-phosphate buffered saline (PBS). Complex 2 displayed an emission band at 511 nm in 5% DMSO-PBS ((ex) = 465 nm) with a fluorescence quantum yield (phi(F)) value of 0.15. Cellular imaging using this complex showed significant mitochondrial localization in HeLa and MCF-7 cancer cells. Complex 3 with a diiodo-BODIPY moiety was non-emissive (phi(F) = 0.01) but acted as an efficient photosensitizer with a singlet oxygen quantum yield value of 0.59 (phi). Complex 3 showed a remarkable PDT effect with apoptotic cell death due to singlet oxygen giving IC50 values within 0.04-0.06 M in HeLa and MCF-7 cells using visible light (400-700 nm), while being less toxic in the dark
SARAS 2: a spectral radiometer for probing cosmic dawn and the epoch of reionization through detection of the global 21-cm signal
No full textThe global 21-cm signal from Cosmic Dawn (CD) and the Epoch of Reionization (EoR), at redshifts , probes the nature of first sources of radiation as well as physics of the Inter-Galactic Medium (IGM). Given that the signal is predicted to be extremely weak, of wide fractional bandwidth, and lies in a frequency range that is dominated by Galactic and Extragalactic foregrounds as well as Radio Frequency Interference, detection of the signal is a daunting task. Critical to the experiment is the manner in which the sky signal is represented through the instrument. It is of utmost importance to design a system whose spectral bandpass and additive spurious signals can be well calibrated and any calibration residual does not mimic the signal. Shaped Antenna measurement of the background RAdio Spectrum (SARAS) is an ongoing experiment that aims to detect the global 21-cm signal. Here we present the design philosophy of the SARAS 2 system and discuss its performance and limitations based on laboratory and field measurements. Laboratory tests with the antenna replaced with a variety of terminations, including a network model for the antenna impedance, show that the gain calibration and modeling of internal additive signals leave no residuals with Fourier amplitudes exceeding 2 mK, or residual Gaussians of 25 MHz width with amplitudes exceeding 2 mK. Thus, even accounting for reflection and radiation efficiency losses in the antenna, the SARAS 2 system is capable of detection of complex 21-cm profiles at the level predicted by currently favoured models for thermal baryon evolution
Neutrophils at the Biological-Material Interface
No full textIntegral to the development of new biomaterials is the characterization of immune responses to biomaterial implants, and formulating methods to overcome or utilize these actions for therapeutic benefit. Neutrophils are an essential component of the immune response against biomaterials, but studies on the neutrophil biomaterial interaction have been largely limited to characterizing their role in establishing an inflammatory microenvironment and antimicrobial activity at implant surfaces. Recent advances in neutrophil biology, especially recognition of their cellular heterogeneity, ability to suppress immune responses, the identification of a new process of cell death, and crosstalk with other immune cell types, have brought about a fundamental change in our perception regarding the activities of neutrophils. Herein, in the context of the progress in our comprehension of neutrophil function, potential avenues for effectively employing neutrophil activity to develop the next generation of regenerative biomaterials are discussed
Detection of Load-Modulated Multiuser MIMO Signals
No full textA load modulated multiple-input multiple-output (MIMO) transmitter uses a single central power amplifier and tunes the antenna loads according to the information signal, eliminating the need for traditional radio frequency (RF) chains (consisting of DACs, mixers, and filters) at the transmitter. In this letter, we consider the use of load modulation (LM) in multiuser MIMO communication on the uplink. Multiple user terminals, each using an LM array (e.g., with 2 or 4 antenna elements), communicate with a base station with multiple receive antennas. First, considering small systems using maximum-likelihood detection, we show that multiuser LM outperforms single-RF chain multiuser systems that employ conventional modulation and spatial modulation. Next, in order to scale multiuser LM to large systems, a low-complexity detection algorithm based on message passing is proposed. The performance of large-scale multiuser LM systems achieved using the proposed algorithm is shown to be better than that achieved in large-scale multiuser systems that employ conventional and spatial modulation
On the Optimality of Secret Key Agreement via Omniscience
No full textFor the multiterminal secret key agreement problem under a private source model, it is known that the maximum key rate, i.e., the secrecy capacity, can be achieved through communication for omniscience, but the omniscience strategy can be strictly suboptimal in terms of minimizing the public discussion rate. While a single-letter characterization is not known for the minimum discussion rate needed for achieving the secrecy capacity, we derive single-letter lower bounds that yield some simple conditions for omniscience to be discussion-rate optimal. These conditions turn out to be enough to deduce the optimality of omniscience for a large class of sources, including the hypergraphical sources. We also extend our results to more general class of multiterminal sources with helpers and silent users
Role of genetic heterogeneity in determining the epidemiological severity of H1 N1 influenza
No full textGenetic differences contribute to variations in the immune response mounted by different individuals to a pathogen. Such differential response can influence the spread of infectious disease, indicating why such diseases impact some populations more than others. Here, we study the impact of population-level genetic heterogeneity on the epidemic spread of different strains of H1 N1 influenza. For a population with known HLA class-I allele frequency and for a given H1 N1 viral strain, we classify individuals into sub-populations according to their level of susceptibility to infection. Our core hypothesis is that the susceptibility of a given individual to a disease such as H1 N1 influenza is inversely proportional to the number of high affinity viral epitopes the individual can present. This number can be extracted from the HLA genetic profile of the individual. We use ethnicity-specific HLA class-I allele frequency data, together with genome sequences of various H1 N1 viral strains, to obtain susceptibility sub-populations for 61 ethnicities and 81 viral strains isolated in 2009, as well as 85 strains isolated in other years. We incorporate these data into a multi-compartment SIR model to analyse the epidemic dynamics for these (ethnicity, viral strain) epidemic pairs. Our results show that HLA allele profiles which lead to a large spread in individual susceptibility values can act as a protective barrier against the spread of influenza. We predict that populations skewed such that a small number of highly susceptible individuals coexist with a large number of less susceptible ones, should exhibit smaller outbreaks than populations with the same average susceptibility but distributed more uniformly across individuals. Our model tracks some well-known qualitative trends of influenza spread worldwide, suggesting that HLA genetic diversity plays a crucial role in determining the spreading potential of different influenza viral strains across populations
On Boolean intervals of finite groups
No full textWe prove a dual version of circle divide ystein Ore's theorem on distributive intervals in the subgroup lattice of finite groups, having a nonzero dual Euler totient phi. For any Boolean group-complemented interval, we observe that phi = phi not equal 0 by the original Ore's theorem. We also discuss some applications in representation theory. We conjecture that cp is always nonzero for Boolean intervals. In order to investigate it, we prove that for any Boolean group-complemented interval H, G], the graded coset poset P=C (H,G) is Cohen Macaulay and the nontrivial reduced Betti number of the order complex Delta(P) is phi, so nonzero. We deduce that these results are true beyond the group-complemented case with vertical bar G : H vertical bar < 32. One observes that they are also true when H is a Borel subgroup of G. (C) 2018 Elsevier Inc. All rights reserved
Absence of Receptor Guanylyl Cyclase C Enhances Ileal Damage and Reduces Cytokine and Antimicrobial Peptide Production during Oral Salmonella enterica Serovar Typhimurium Infection
No full textNontyphoidal Salmonella disease contributes toward significant morbidity and mortality across the world. Host factors, including gamma interferon, tumor necrosis factor alpha, and gut microbiota, significantly influence the outcome of Salmonella pathogenesis. However, the entire repertoire of host protective mechanisms contributing to Salmonella pathogenicity is not completely appreciated. Here, we investigated the roles of receptor guanylyl cyclase C (GC-C), which is predominantly expressed in the intestine and regulates intestinal cell proliferation and fluid-ion homeostasis. Mice deficient in GC-C (Gucy2c(-/-)) displayed accelerated mortality compared with that for wild-type mice following infection via the oral route, even though both groups possessed comparable systemic Salmonella infection burdens. Survival following intraperitoneal infection remained similar in both groups, indicating that GC-C offered protection via a gut-mediated response. The serum cortisol level was higher in Gucy2c(-/-) mice than wild-type (Gucy2c(-/-)) mice, and an increase in infection-induced thymic atrophy with a loss of immature CD4(+) CD8(+) double-positive thymocytes was observed. Accelerated and enhanced damage in the ileum, including submucosal edema, epithelial cell damage, focal tufting, and distortion of the villus architecture, was seen in Gucy2c(-/-) mice concomitantly with a larger number of ileal tissue-associated bacteria. Transcription of key mediators of Salmonella-induced inflammation (interleukin-22/Reg3 beta) was altered in Gucy2c(-/-) mice in comparison to that in Gucy2c(-/-) mice. A reduction in fecal lactobacilli, which are protective against Salmonella infection, was observed in Gucy2c(-/-) mice. Gucy2c(-/-) mice cohoused with wild-type mice continued to show reduced amounts of lactobacilli and increased susceptibility to infection. Our study, therefore, suggests that the receptor GC-C confers a survival advantage during gut-mediated Salmonella enterica serovar Typhimurium pathogenesis, presumably by regulating Salmonella effector mechanisms and maintaining a beneficial microbiome