The Orbital Structure of Dark Matter Halos with Gas

With the success of the Chandra and XMM missions and the maturation of gravitational lensing techniques, powerful constraints on the orbital structure of cluster dark matter halos are possible. I show that the X-ray emissivity and mass of a galaxy cluster uniquely specify the anisotropy and velocity dispersion profiles of its dark matter halo. I consider hydrostatic as well as cooling flow scenarios, and apply the formalism to the lensing cluster CL0024+16 and the cooling flow cluster Abell 2199. In both cases, the model predicts a parameter-free velocity dispersion profile that is consistent with independent optical redshift surveys of the clusters.Comment: 17 pages, 12 figures; to appear in the Astrophysical Journa

A Multiband OFDMA Heterogeneous Network for Millimeter Wave 5G Wireless Applications

Citation: Niknam, S., Nasir, A. A., Mehrpouyan, H., & Natarajan, B. (2016). A Multiband OFDMA Heterogeneous Network for Millimeter Wave 5G Wireless Applications. Ieee Access, 4, 5640-5648. doi:10.1109/access.2016.2604364Emerging fifth generation (5G) wireless networks require massive bandwidth in higher frequency bands, extreme network densities, and flexibility of supporting multiple wireless technologies in order to provide higher data rates and seamless coverage. It is expected that the utilization of the large bandwidth in the millimeter-wave (mmWave) band and deployment of heterogeneous networks (HetNets) will help address the data rate requirements of 5G networks. However, high pathloss and shadowing in the mmWave frequency band, strong interference in the HetNets due to massive network densification, and coordination of various air interfaces are challenges that must be addressed. In this paper, we consider a relay based multiband orthogonal frequency division multiple access HetNet in which mmWave small cells are deployed within the service area of macro cells. In particular, we attempt to exploit the distinct propagation characteristics of mmWave bands (i.e., 60 GHz-the V-band and 70-80 GHz the E-band) and the long term evolution band to maximize overall data rate of the network via efficient resource allocation. The problem is solved using a modified dual decomposition approach and then a low complexity greedy solution based on the iterative activity selection algorithm is presented. Simulation results show that the proposed approach outperforms conventional schemes

Evaluation of the feasibility and acceptability of the 'Care for Stroke' intervention in India, a smartphone-enabled, carer-supported, educational intervention for management of disability following stroke.

OBJECTIVES: (1) To identify operational issues encountered by study participants in using the 'Care for Stroke' intervention; (2) to evaluate the feasibility and acceptability of the intervention. DESIGN: Mixed-methods research design. SETTING: Participant's home. Participants were selected from a tertiary hospital in Chennai, South India. PARTICIPANTS: Sixty stroke survivors treated and discharged from the hospital, and their caregivers. INTERVENTION: 'Care for Stroke' is a smartphone-enabled, educational intervention for management of physical disabilities following stroke. It is delivered through a web-based, smartphone-enabled application. It includes inputs from stroke rehabilitation experts in a digitised format. METHODS: Evaluation of the intervention was completed in two phases. In the first phase, the preliminary intervention was field-tested with 30 stroke survivors for 2 weeks. In the second phase, the finalised intervention was provided to a further 30 stroke survivors to be used in their homes with support from their carers for 4 weeks. PRIMARY AND SECONDARY OUTCOME MEASURES: PRIMARY OUTCOMES: (1) operational difficulties in using the intervention; (2) feasibility and acceptability of the intervention in an Indian setting. Disability and dependency were assessed as secondary outcomes. RESULTS: Field-testing identified operational difficulties related to connectivity, video-streaming, picture clarity, quality of videos, and functionality of the application. The intervention was reviewed, revised and finalised before pilot-testing. Findings from the pilot-testing showed that the 'Care for Stroke' intervention was feasible and acceptable. Over 90% (n=27) of the study participants felt that the intervention was relevant, comprehensible and useful. Over 96% (n=29) of the stroke survivors and all the caregivers (100%, n=30) rated the intervention as excellent and very useful. These findings were supported by qualitative interviews. CONCLUSIONS: Evaluation indicated that the 'Care for Stroke' intervention was feasible and acceptable in an Indian context. An assessment of effectiveness is now warranted

The statistics of particle velocities in dense granular flows

We present measurements of the particle velocity distribution in the flow of granular material through vertical channels. Our study is confined to dense, slow flows where the material shears like a fluid only in thin layers adjacent to the walls, while a large core moves without continuous deformation, like a solid. We find the velocity distribution to be non-Gaussian, anisotropic, and to follow a power law at large velocities. Remarkably, the distribution is identical in the fluid-like and solid-like regions. The velocity variance is maximum at the core, defying predictions of hydrodynamic theories. We show evidence of spatially correlated motion, and propose a mechanism for the generation of fluctuational motion in the absence of shear.Comment: Submitted to Phys. Rev. Let

Calibrations of hydro-acoustic instruments onboard FORV Sagar Sampada

Calibration is carried out to keep up the precision of the instruments by determining their calibre. CaUbration of hydro acoustic equipments onboard FORV Sagar Sampada was carried out periodically and the performance records were maintained. Deviation and the deficiencies were noted down for applying the correction while interpreting the output of the instruments

Nonlinear Modes of Liquid Drops as Solitary Waves

The nolinear hydrodynamic equations of the surface of a liquid drop are shown to be directly connected to Korteweg de Vries (KdV, MKdV) systems, giving traveling solutions that are cnoidal waves. They generate multiscale patterns ranging from small harmonic oscillations (linearized model), to nonlinear oscillations, up through solitary waves. These non-axis-symmetric localized shapes are also described by a KdV Hamiltonian system. Recently such ``rotons'' were observed experimentally when the shape oscillations of a droplet became nonlinear. The results apply to drop-like systems from cluster formation to stellar models, including hyperdeformed nuclei and fission.Comment: 11 pages RevTex, 1 figure p

A Preliminary Investigation towards the Risk Stratification of Allogeneic Stem Cell Recipients with Respect to the Potential for Development of GVHD via Their Pre-Transplant Plasma Lipid and Metabolic Signature

The clinical outcome of allogeneic hematopoietic stem cell transplantation (SCT) may be influenced by the metabolic status of the recipient following conditioning, which in turn may enable risk stratification with respect to the development of transplant-associated complications such as graft vs. host disease (GVHD). To better understand the impact of the metabolic profile of transplant recipients on post-transplant alloreactivity, we investigated the metabolic signature of 14 patients undergoing myeloablative conditioning followed by either human leukocyte antigen (HLA)-matched related or unrelated donor SCT, or autologous SCT. Blood samples were taken following conditioning and prior to transplant on day 0 and the plasma was comprehensively characterized with respect to its lipidome and metabolome via liquid chromatography/mass spectrometry (LCMS) and gas chromatography/mass spectrometry (GCMS). A pro-inflammatory metabolic profile was observed in patients who eventually developed GVHD. Five potential pre-transplant biomarkers, 2-aminobutyric acid, 1-monopalmitin, diacylglycerols (DG 38:5, DG 38:6), and fatty acid FA 20:1 demonstrated high sensitivity and specificity towards predicting post-transplant GVHD. The resulting predictive model demonstrated an estimated predictive accuracy of risk stratification of 100%, with area under the curve of the ROC of 0.995. The likelihood ratio of 1-monopalmitin (infinity), DG 38:5 (6.0), and DG 38:6 (6.0) also demonstrated that a patient with a positive test result for these biomarkers following conditioning and prior to transplant will be at risk of developing GVHD. Collectively, the data suggest the possibility that pre-transplant metabolic signature may be used for risk stratification of SCT recipients with respect to development of alloreactivity

Measuring the dark matter velocity anisotropy in galaxy clusters

The Universe contains approximately 6 times more dark matter than normal baryonic matter, and a directly observed fundamental difference between dark matter and baryons would both be significant for our understanding of dark matter structures and provide us with information about the basic characteristics of the dark matter particle. We discuss one distinctive feature of dark matter structures in equilibrium, namely the property that a local dark matter temperature may depend on direction. This is in stark contrast to baryonic gases. We used X-ray observations of two nearby, relaxed galaxy clusters, under the assumptions of hydrostatic equilibrium and identical dark matter and gas temperatures in the outer cluster region, to measure this dark matter temperature anisotropy beta_dm, with non-parametric Monte Carlo methods. We find that beta_dm is greater than the value predicted for baryonic gases, beta_gas=0, at more than 3 sigma confidence. The observed value of the temperature anisotropy is in fair agreement with the results of cosmological N-body simulations and shows that the equilibration of the dark matter particles is not governed by local point-like interactions in contrast to baryonic gases.Comment: 5 pages, 3 figures, extended discussions, matches accepted versio

Analytic models of plausible gravitational lens potentials

Gravitational lenses on galaxy scales are plausibly modelled as having ellipsoidal symmetry and a universal dark matter density profile, with a Sersic profile to describe the distribution of baryonic matter. Predicting all lensing effects requires knowledge of the total lens potential: in this work we give analytic forms for that of the above hybrid model. Emphasising that complex lens potentials can be constructed from simpler components in linear combination, we provide a recipe for attaining elliptical symmetry in either projected mass or lens potential. We also provide analytic formulae for the lens potentials of Sersic profiles for integer and half-integer index. We then present formulae describing the gravitational lensing effects due to smoothly-truncated universal density profiles in cold dark matter model. For our isolated haloes the density profile falls off as radius to the minus fifth or seventh power beyond the tidal radius, functional forms that allow all orders of lens potential derivatives to be calculated analytically, while ensuring a non-divergent total mass. We show how the observables predicted by this profile differ from that of the original infinite-mass NFW profile. Expressions for the gravitational flexion are highlighted. We show how decreasing the tidal radius allows stripped haloes to be modelled, providing a framework for a fuller investigation of dark matter substructure in galaxies and clusters. Finally we remark on the need for finite mass halo profiles when doing cosmological ray-tracing simulations, and the need for readily-calculable higher order derivatives of the lens potential when studying catastrophes in strong lenses.Comment: 24 pages, 10 figures, matches published versio