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Glacier-Surface Velocity Derived Ice Volume and Retreat Assessment in the Dhauliganga Basin, Central Himalaya - A Remote Sensing and Modeling Based Approach
No full textHimalayan glaciers are a storehouse of fresh water and play a significant role in influencing the runoff through numerous perennial rivers flowing over the Indo-Gangetic plains, providing freshwater to the second largest populated country in the world. For suitable management of this water resource, measurement of glacier-ice volume is extremely important in the current scenario of climate change and water scarcity. To address this concern, the present study endeavors to find a suitable methodology to quantify glacier volume and retreat in the Central Himalaya. Herein, two methods were implemented to estimate the total glacier ice volume - conventional area-based scaling method and glacier-surface velocity based modeling technique. The availability of field data allowed a validation assessment to be carried out on two Himalayan glaciers (Chhota Shigri and Satopanth). Here, we propose a volume-area power law, appropriate for the application in the context of Himalayan glaciers. The ice volume of 15 glaciers larger than 1 km(2) calculated using a spatially distributed ice thickness model is 3.78 x 10(9) m(3) (f = 0.8), with an overall uncertainty of 18.4%. The total volume of the remaining glaciers in the basin, calculated using a tuned volume-area scaling relation is 2.71 x 10(9) m(3). A sensitivity analysis is performed to evaluate the influence of input parameters on the model and volume-area scaling performance. The study also incorporates investigation of the glacier bed topography for discrete identification of the overdeepening sites in the glacier valley which are potential lake formation sites in the future. A total of 54 overdeepening sites covering an area of 2.85 km(2) have been identified. In addition, the relative glacier area loss of the glaciers is investigated using historical CORONA and Landsat satellite imageries. Glaciers with a smaller area and those with lower mean ice thickness near the terminus shrank significantly more, as compared to the larger ones. The total area of the selected larger glaciers is estimated to be 68 km(2) in 2015 and deglaciation of 4.7 km(2) is observed over the period of 48 years that accounts for 6.9% of the total area in 1968
Measurement of inclusive very forward jet cross sections in proton-lead collisions at p sNN=5:02 TeV
No full textMeasurements of differential cross sections for inclusive very forward jet production in proton-lead collisions as a function of jet energy are presented. The data were collected with the CMS experiment at the LHC in the laboratory pseudorapidity range 6 : 6 < < 5 : 2. Asymmetric beam energies of 4TeV for protons and 1.58TeV per nucleon for Pb nuclei were used, corresponding to a center-of-mass energy per nucleon pair of p sNN = 5 : 02TeV. Collisions with either the proton (p+ Pb) or the ion (Pb+ p) traveling towards the negative hemisphere are studied. The jet cross sections are unfolded to stable-particle level cross sections with pT & 3 GeV, and compared to predictions from various Monte Carlo event generators. In addition, the cross section ratio of p+ Pb and Pb+ p data is presented. The results are discussed in terms of the saturation of gluon densities at low fractional parton momenta. None of the models under consideration describes all the data over the full jet-energy range and for all beam con fi gurations. Discrepancies between the di ff erential cross sections in data and model predictions of more than two orders of magnitude are observed
Molecular-Level Insights into the Microstructure of a Hydrated and Nanoconfined Deep Eutectic Solvent
No full textDespite the recent advancements in the field of deep eutectic solvents (DESs), their high viscosity often prevents practical applications. A versatile strategy to overcome this problem is either to add a co-solvent or to confine the DES inside a nanoscaled self-organized system. This work assesses the microstructures of a hydrated and nanoconfined DES comprising benzyltripropylammonium chloride BTPA]CI and ethylene glycol (EG). They act as a hydrogen-bond acceptor and a donor, respectively. The hydrogen bonding between BTPA]CI and EG in the DES (i.e., BTEG) and the molecular states of water in the hydrated BTEG were studied by Raman spectroscopy. The results show different hydrogen-bonding associations between water- water and water -BTEG or EG molecules. In addition, we investigated the confinement effects of BTEG in a Polysorbate 80 (Tween-80)/cyclohexane reverse micellar (RM) system. The results are compared with those of an ionic liquid-encapsulated RM system. The formation, bonding characteristics, and thermal stability of the RM droplets were studied by solubilization, dynamic light scattering, rheology, and Raman spectroscopy experiments. Furthermore, it is shown that hydrogen bonding between the DES and the surfactant leads to a stable RM system. Interestingly, the viscosity of the RM system is significantly lower than that of the neat DES suggesting that DESs have a much wider practical applicability in the form of RMs
Understanding and Improving the Performance of Constructive Interference Using Destructive Interference in WSNs
No full textThe constructive interference (CI) phenomenon has been exploited by a number of protocols for providing energy-efficient, low-latency, and reliable data collection and dissemination services in wireless sensor networks. These protocols consider CI to provide highly reliable packet delivery. This has attracted attention to understand the working of CI; however, the existing works present inconsistent views. Furthermore, these works do not study in the real-world settings where the physical conditions of deployment and unreliable wireless channels also impact the performance of CI. Therefore, we study the phenomenon of CI, considering a receiver's viewpoint and analyze the parameters that affect CI. We validate our arguments with results from extensive and rigorous experimentation in real-world settings. This paper presents comprehensive insights into the CI phenomenon. With the understanding, we develop the destructive interference-based power adaptation (DIPA), an energy-efficient and distributed algorithm, that adapts transmission power to improve the performance of CI. Since CI-based protocols cannot have an explicit acknowledgment packet, we make use of destructive interference on a designated byte to provide a feedback. We leverage this feedback to adapt transmission powers. We compared CI with and without DIPA in two real-life testbeds. On one testbed, we achieve around 25% lower packet losses while using only half of its transmission power for 64-B packets. On the other testbed, we achieve 25% lower packet losses while consuming only 47% of its transmission power for 128-B packets. Existing CI-based protocols can easily incorporate DIPA into them to achieve lower packet losses and higher energy efficiencies
Effect of methylamine vapor exposure and ambient ageing on Cs(x)MA(1-x)PbI(3-x)Br(x) perovskites for improved carrier collection
No full textCaesium-methylammonium lead iodide-bromide perovskites (Cs(x)MA(1-x)PbI(3-x)Br(x)) is interesting for stable and high-voltage tandem solar cells. Here, we report a systematic material and device study of Cs(x)MA(1-x)PbI(3-x)Br(x) (x = 0, 5, 10 and 15%) perovskite films. Cs-Br incorporation reduces carrier lifetime of as-deposited films, from 21.5 mu s for x = 0% to 5.8 mu s for x = 15%. Unlike pure MA films, Cs-Br incorporated films were not only more resilient to degradation, their carrier lifetime increased by 50%-300% when exposed to ambient due to the humidity-assisted healing. The morphology of asdeposited films was poor. Methylamine vapor exposure (MVE) was used to improve the morphology and crystallinity, which further improved carrier lifetime up to 50 ps. Devices with efficiency >17% were fabricated on MVE treated Cs(0.10)MA(0.90)PbI(2.90)Br(0.10) films. The short circuit current density was further increased by fabricating devices on `aged' films which have higher lifetime due to humidity healing. Best Cs(0.10)MA(0.90)PbI(2.90)Br(0.10) devices show good ambient stability with V-OC and FF unchanged even after 5 days of ambient exposure
Flexible silicon nitride photonic integrated circuit embedded in polymer handle
No full textIn this paper, we present a hybrid process to make a flexible photonic circuit. The photonic circuit is fabricated on a Silicon substrate with PECVD Silicon Nitride (SiN) as a waveguide layer on an oxide layer. The SiN waveguide circuit is fabricated using conventional lithography and dry etching followed by Si substrate thinned down to 10micrometer. The thin-film photonic circuit integrity after wafer-thinning and layer transfer is characterized by the waveguide performance, grating coupler efficiency and ring resonator performance. We observe no degradation in device and circuit performance. We present detailed process flow, SiN-to-PDMS embedding process and detailed device characterization
Revisiting Censoring in Energy Harvesting Wireless Sensor Networks
No full textCensoring improves the lifetime of conventional wireless sensor networks (WSNs) by reducing the number of sensor node transmissions. However, this comes at the expense of performance since measurements from fewer nodes are available. We show that in energy harvesting (EH) WSNs, in which the sensor nodes harvest energy from the environment, this trade-off is fundamentally different. For a general model in which the nodes experience independent and non-identical fading and the EH process at a node is stationary and ergodic, we derive a lower bound on the mean squared error (MSE). It leads to an insightful and explicit characterization of the optimum censoring threshold for each node. We show that it is the point at which the probability that an EH node has sufficient energy to transmit becomes 1. We also analyze the MSE outage probability, which is an alternate and widely used performance measure, which characterizes the impact of channel fading
Optimal Scalar Linear Index Codes for Some Two-Sender Unicast Index Coding Problems
No full textIn this paper, two-sender unicast index coding problem (TUICP) is studied, where the senders possibly have some messages in common, and each receiver requests a unique message. It is analyzed using three independent subproblems (which are single-sender unicast index coding problems (SUICPs)) and the interactions among them. These sub-problems are described by three disjoint vertex-induced subgraphs of the side-information graph of the TUICP respectively, based on the availability of messages at the senders. The TUICP is classified based on the type of interactions among the sub-problems. Optimal scalar linear index codes for a class of TUICP are obtained using those of the sub-problems. For two classes, we identify a sub-class for which scalar linear codes are obtained using the notion of joint extensions of SUICPs. An SUICP I-E is said to be a joint extension of l SUICPs if the fitting matrices of all the l SUICPs are disjoint submatrices of that of I-E. Joint extensions generalize the notion of rank-invariant extensions. Scalar linear codes and a condition for optimality of the codes are given for a class of joint extensions. Using this result, scalar linear codes and the conditions for their optimality are obtained for two classes of the TUICP
Conversion of random X-inactivation to imprinted X-inactivation by maternal PRC2
No full textImprinted X-inactivation silences genes exclusively on the paternally-inherited X-chromosome and is a paradigm of transgenerational epigenetic inheritance in mammals. Here, we test the role of maternal vs. zygotic Polycomb repressive complex 2 (PRC2) protein EED in orchestrating imprinted X-inactivation in mouse embryos. In maternal-null (Eed(m-/-)) but not zygotic null (Eed(-/-)) early embryos, the maternal X-chromosome ectopically induced Xist and underwent inactivation. Eed(m-/-) females subsequently stochastically silenced Xist from one of the two X-chromosomes and displayed random X-inactivation. This effect was exacerbated in embryos lacking both maternal and zygotic EED (Eed(mz-/-)), suggesting that zygotic EED can also contribute to the onset of imprinted X-inactivation. Xist expression dynamics in Eed(m-/-) embryos resemble that of early human embryos, which lack oocyte-derived maternal PRC2 and only undergo random X-inactivation. Thus, expression of PRC2 in the oocyte and transmission of the gene products to the embryo may dictate the occurrence of imprinted X-inactivation in mammals
Catalytic enantioselective Michael addition of deconjugated butyrolactams to maleimides
No full textThe first catalytic enantioselective Michael addition of deconjugated butyrolactams to N-arylmaleimides is developed with the help of a bifunctional tertiary aminosquaramide catalyst. Unlike the widely explored and structurally related vinylogous nucleophile - deconjugated butenolides, deconjugated butyrolactams are found to be exclusively alpha-selective. The resulting highly substituted and densely functionalized products, bearing contiguous all-carbon quaternary and tertiary stereocenters, are formed in good yields with moderate diastereoselectivity and good to excellent enantioselectivity (up to 99:1 er)