522 research outputs found
Wet and Dry Spells over Southeast Peninsular India
The southeast peninsular India contains, to name a few, several important cities crucial for trade and economic growth of the country, rice bowls, institutes for science and technology, space port, etc. Despite its importance, not many reports exist on rainfall and its variation on different temporal scales over this region during southwest monsoon, partly because the rainfall in this region is relatively less and it forms only a minor part of all India rainfall. Here, an attempt has been made to understand differences in thermal and dynamical characteristics and energetics of the atmosphere between wet and dry spells of the Indian summer monsoon over the southeast India by utilizing various observations and reanalysis products. Observations demonstrate that the difference in the thermal structure between wet and dry spells is significant only in the lower troposphere (< 2-3 km) with mean CAPE values are reaching as much as 1000 Jkg-1during wet spell. Vertical buoyancy profiles indicate the bi-modal distribution during dry spells with peaks in 700 and 500 hPa levels. The observed thermal features are not confined to Gadanki but seen over entire southeast peninsular India. Associated dynamical variations also exhibit obvious differences during wet and dry spell. The diurnal variation of winds exhibits difference in amplitude and phase are remarkably large during dry spell than in wet spell. Synthesis are all the measurements indicates that the thermal and dynamical differences observed in wet and dry spells are pronounced in the boundary layer
Efficient replica-exchange across distributed production infrastructure
Replica-Exchange (RE) methods represent a class of algorithms that involve a large number of loosely-coupled ensembles and are used to understand physical phenomena -- ranging from protein folding dynamics to binding affinity calculations. We develop a framework for RE that supports different replica pairing and coordination mechanisms, that can use a wide range of production cyberinfrastructure concurrently. Additionally, our framework uses a flexible pilot-job implementation, which enables effective resource allocation for multiple replicas. We characterize the performance of two different RE algorithms - synchronous and asynchronous - at unprecedented scales on production distributed infrastructure (Teragrid and LONI). The synchronous RE algorithm is implemented with a centralized master, while the asynchronous RE algorithm is implemented with both centralized and decentralized replica management schemes. We evaluate the performance of the different algorithms and implementations when we scale-up the number of replicas (up to 256) on a single machine and when we scale-out across 2 and 4 machines. Both the synchronous and asynchronous algorithms perform similarly when the number of replicas is small. But as the number of replicas increase, in the synchronous RE, the synchronization cost increases the total time to completion. In the centralized asynchronous RE, the cost of managing many replicas in a centralized manner increases the time to completion but not as much as in the synchronous RE. The decentralized asynchronous RE scales much better with increasing number of replicas. When scaled-out across many machines, the performance of synchronous RE depends on whether the machines are homogeneous or heterogeneous. A heterogeneous infrastructure means increased synchronization costs. We also run tests to see if one of the algorithms is better suited to achieve more crosswalks and temperature mixing -- better sampling
Magnetocaloric effect and improved relative cooling power in (La0.7Sr0.3MnO3/SrRuO3) superlattices
Magnetic properties of a series of (La0.7Sr0.3MnO3/SrRuO3) superlattices,
where the SrRuO3 layer thickness is varying, are examined. A room-temperature
magnetocaloric effect is obtained owing to the finite size effect which reduces
the TC of La0.7Sr0.3MnO3 layers. While the working temperature ranges are
enlarged,, -DeltaSmax values remains similar to the values in polycrystalline
La0.7Sr0.3MnO3. Consequently, the relative cooling powers are significantly
improved, the microscopic mechanism of which is related to the effect of the
interfaces at La0.7Sr0.3MnO3/SrRuO3 and higher nanostructural disorder. This
study indicates that artificial oxide superlattices/multilayers might provide
an alternative pathway in searching for efficient room-temperature magnetic
refrigerators for (nano)microscale systems.Comment: 14^pages, 3 figures, Submitted to J. Phys. Cond. Ma
Optimized Analysis of the AC Magnetic Susceptibility Data in Several Spin-Glass Systems using the Vogel-Fulcher and Power Laws
In spin-glasses (SG), the relaxation time () vs.
data at the peak position in the temperature variation of the ac magnetic
susceptibilities at different frequencies f is often fit to the Vogel-Fulcher
Law (VFL): and to the Power Law (PL): . Both these laws have three fitting
parameters each, leaving a degree of uncertainty since the magnitudes of the
evaluated parameters , , and depend
strongly on the choice of and . Here we report an optimized
procedure for the analysis of vs. data on several SG systems for
which we could extract such data from published sources. In this optimized
method, the data of vs. are fit by varying in the linear
plots of vs for the VFL and by varying in
the linear plot of vs. for the PL till
optimum fits are obtained. The analysis of the associated magnitudes of
, , and for these optimum values of
and shows that magnitudes of , and fail to
provide a clear distinction between canonical and cluster SG. However, new
results emerge showing in canonical SG whereas for cluster SG systems and the optimized optimized in all
cases. Although some interpretation of these new results is presented, a more
rigorous theoretical justification of the boundary near
is desired along with testing of these criteria in other SG systems.Comment: 33 pages, 4 main figures, 15 figures in the supplementary document.
The following article has been submitted to AIP Advance
Dendronylation: Residue-specific chemoselective attachment of oligoglycerol dendrimers on proteins with noncanonical amino acids
Polyglycerol dendrimers as an important class of polymeric materials especially attractive for covalent attachment to therapeutic proteins as a useful alternative to traditional PEGylation procedures. Herein, we combine in vivo noncanonical amino acid (ncAA) incorporation and chemoselective conjugation in vitro to produce novel hybrid protein–dendrimer conjugates with the defined architectures. We incorporated Azidohomoalanine (Aha) as methionine substitute in vivo into various protein scaffolds to allow non-invasive dendrimer conjugations (dendronylation). Our approach makes recombinant proteins accessible for the design of multivalent dendrimer conjugates since it enables the preparation of many sequences with various positions for regioselective dendronylation
Application of bifurcation methods for the prediction of low-speed aircraft ground performance
The design of aircraft for ground maneuvers is an essential part in satisfying the demanding requirements of the aircraft operators. Extensive analysis is done to ensure that a new civil aircraft type will adhere to these requirements, for which the nonlinear nature of the problem generally adds to the complexity of such calculations. Small perturbations in velocity, steering angle, or brake application may lead to significant differences in the final turn widths that can be achieved. Here, the U-turn maneuver is analyzed in detail, with a comparison between the two ways in which this maneuver is conducted. A comparison is also made between existing turn-width prediction methods that consist mainly of geometric methods and simulations and a proposed new method that uses dynamical systems theory. Some assumptions are made with regard to the transient behavior, for which it is shown that these assumptions are conservative when an upper bound is chosen for the transient distance. Furthermore, we demonstrate that the results from the dynamical systems analysis are sufficiently close to the results from simulations to be used as a valuable design tool. Overall, dynamical systems methods provide an order-of-magnitude increase in analysis speed and capability for the prediction of turn widths on the ground when compared with simulations. Nomenclature co = oleo damping coefficient, N s2 =m2 cz = tire vertical damping coefficient Fco = damping force in oleo due to the orifice,
Towards engineering of self-assembled nanostructures using non-ionic dendritic amphiphiles
Engineering nanostructures of defined size and morphology is a great challenge
in the field of self-assembly. Herein we report on the formation of
supramolecular nanostructures of defined morphologies with subtle structural
changes for a new series of dendritic amphiphiles. Subsequently, we studied
their application as nanocarriers for guest molecules
Institutional experience of tuberculosis of craniovertebral junction
Background: Craniovertebral junction tuberculosis (CVJ-TB) is a rare entity occurring in only 0.3 to 1% of tuberculous spondylitis. It causes severe instability and neurological deficits. Present study includes 16 cases of CVJ tuberculosis with neck pain and progressive quadriparesis. Radiological evaluation showed wide spread disease around clivus, C1, C2, C3 with extensive bony destruction, cord compression, basilar invagination and atlantoaxial dislocation.Methods: The study included all the cases admitted with cv junction tuberculosis in neurosurgery ward in King George hospital, Visakhapatnam during a period of three years from 2014 to 2016. Four cases were managed conservatively and four cases were treated by only posterior occipitocervical fusion. We performed two stage operation in single sitting i.e. transoral decompression and posterior occipitocervical fusion in 12 cases. The pathological findings confirmed tuberculosis.Results: Postoperatively all the patients had decreased neck pain and two third of the patients (10 of 16 patients) had improvement in motor power.Conclusions: In the available literature, the treatment options offered for cvj-tb have ranged from a purely conservative approach to radical surgery without well-defined guidelines. In this study, we followed a radical approach as the patients included in our study presented with extensive TB cv junction. So, we recommend radical surgery for extensive TB of cv junction
Insuring Smiles: Predicting routine dental coverage using Spark ML
Finding suitable health insurance coverage can be challenging for individuals
and small enterprises in the USA. The Health Insurance Exchange Public Use
Files (Exchange PUFs) dataset provided by CMS offers valuable information on
health and dental policies [1]. In this paper, we leverage machine learning
algorithms to predict if a health insurance plan covers routine dental services
for adults. By analyzing plan type, region, deductibles, out-of-pocket
maximums, and copayments, we employ Logistic Regression, Decision Tree, Random
Forest, Gradient Boost, Factorization Model and Support Vector Machine
algorithms. Our goal is to provide a clinical strategy for individuals and
families to select the most suitable insurance plan based on income and
expenses.Comment: 4 pages, 13 figures, 5 table
Controlled self-assembly of stomatosomes by use of single-component fluorinated dendritic amphiphiles
A series of novel non-ionic amphiphiles with dendritic oligoglycerol head groups of different generations ([G1]–[G3]) and lipophilic/fluorophilic tail segments, comprising single or double tail alkyl chains, C8F17-perfluoro rod segments as well as flexible spacer groups of different lengths were designed and synthesized. We expected that the differences in the size of the dendritic head groups in combination with perfluorinated segments would have an impact on the supramolecular structures formed in aqueous solution if compared with the hydrogenated analogues. Investigating the self-assembly behavior mainly by cryogenic transmission electron microscopy (cryo-TEM) and cryo-electron tomography (cryo-ET) we found as a new result the formation of perforated bilayer vesicles (stomatosomes) and bicontinuous network structures. Surprisingly, we have observed stomatosome formation by self-assembly of single component fluorinated dendritic amphiphiles. These assembly structures turned out to be extremely robust against harsh conditions, although there are strong indications that they represent non-equilibrium structures, which eventually transform into a bicontinuous cubic network structure of double diamond symmetry. In general, the molecular asymmetry of amphiphiles tuned by chemical design induced the expected trend from spherical micelles through worm-like micelles to perforated bilayers and three-dimensional network structures
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