Sterile Neutrino Hot, Warm, and Cold Dark Matter

We calculate the incoherent resonant and non-resonant scattering production of sterile neutrinos in the early universe. We find ranges of sterile neutrino masses, vacuum mixing angles, and initial lepton numbers which allow these species to constitute viable hot, warm, and cold dark matter (HDM, WDM, CDM) candidates which meet observational constraints. The constraints considered here include energy loss in core collapse supernovae, energy density limits at big bang nucleosynthesis, and those stemming from sterile neutrino decay: limits from observed cosmic microwave background anisotropies, diffuse extragalactic background radiation, and Li-6/D overproduction. Our calculations explicitly include matter effects, both effective mixing angle suppression and enhancement (MSW resonance), as well as quantum damping. We for the first time properly include all finite temperature effects, dilution resulting from the annihilation or disappearance of relativistic degrees of freedom, and the scattering-rate-enhancing effects of particle-antiparticle pairs (muons, tauons, quarks) at high temperature in the early universe.Comment: 24 pages, including 8 figures. v3: to match version in PRD, added references and numerous minor changes. High resolution color figures available at http://superbeast.ucsd.edu/~kev/nucd

An experimental and theoretical study of the flow phenomena within a vortex sink rate sensor

Tests were conducted to obtain a description of the flow field within a vortex sink rate sensor and to observe the influence of viscous effects on its performance. The characteristics of the sensor are described. The method for conducting the test is reported. It was determined that for a specific mass flow rate and the geometry of the vortex chamber, the flow in the vortex chamber was only affected, locally, by the size of the sink tube diameter. Within the sink tube, all three velocity components were found to be higher for the small sink tube diameters. As the speed of rotation of the sensor was increased, the tangential velocities within the vortex chamber, as well as in the sink tube, increased in proportion to the speed of rotation

Search on a Hypercubic Lattice through a Quantum Random Walk: II. d=2

We investigate the spatial search problem on the two-dimensional square lattice, using the Dirac evolution operator discretised according to the staggered lattice fermion formalism. $d=2$ is the critical dimension for the spatial search problem, where infrared divergence of the evolution operator leads to logarithmic factors in the scaling behaviour. As a result, the construction used in our accompanying article \cite{dgt2search} provides an $O(\sqrt{N}\log N)$ algorithm, which is not optimal. The scaling behaviour can be improved to $O(\sqrt{N\log N})$ by cleverly controlling the massless Dirac evolution operator by an ancilla qubit, as proposed by Tulsi \cite{tulsi}. We reinterpret the ancilla control as introduction of an effective mass at the marked vertex, and optimise the proportionality constants of the scaling behaviour of the algorithm by numerically tuning the parameters.Comment: Revtex4, 5 pages (v2) Introduction and references expanded. Published versio

Search on a Hypercubic Lattice using a Quantum Random Walk: I. d>2

Random walks describe diffusion processes, where movement at every time step is restricted to only the neighbouring locations. We construct a quantum random walk algorithm, based on discretisation of the Dirac evolution operator inspired by staggered lattice fermions. We use it to investigate the spatial search problem, i.e. finding a marked vertex on a $d$-dimensional hypercubic lattice. The restriction on movement hardly matters for $d>2$, and scaling behaviour close to Grover's optimal algorithm (which has no restriction on movement) can be achieved. Using numerical simulations, we optimise the proportionality constants of the scaling behaviour, and demonstrate the approach to that for Grover's algorithm (equivalent to the mean field theory or the $d\to\infty$ limit). In particular, the scaling behaviour for $d=3$ is only about 25% higher than the optimal $d\to\infty$ value.Comment: 11 pages, Revtex (v2) Introduction and references expanded. Published versio

Singularity Free Inhomogeneous Models with Heat Flow

We present a class of singularity free exact cosmological solutions of Einstein's equations describing a perfect fluid with heat flow. It is obtained as generalization of the Senovilla class [1] corresponding to incoherent radiation field. The spacetime is cylindrically symmetric and globally regular.Comment: 6 pages, TeX, to appear in Class.Quant.Gra

Diabetic foot resulting in amputation: our experience

Background: The aim of our study was to early diagnosis of diabetic foot so that the complications can be prevented, to control the systemic infection and prevent the complications, to study the effectiveness of regular dressing in diabetic foot so as to prevent the local spread of infection and the ulcer and to conclude that early diagnosis, care and proper meticulous treatment of diabetic foot can prevent amputation. Methods: The present study was prospective, observational and longitudinal. Protocol of the procedure was formed along with Performa, Patient Information Sheet, Informed Consent Form and approval from Ethical Committee. The present study was carried out in surgery department of C.U Shah medical college, Surendranagar; Gujarat state. The study was carried out from 1st August 2011 to 30th September 2013. A total of one hundred patients admitted in surgery ward with diabetes type 1 or 2 with ulcer on foot having grade 1 or 2 of Wagner’s classification without any other co morbid condition. These patients undergo daily dressing with various dressing solutions according to their ulcer characteristics. All the patients given diet/oral hypoglycaemic drug/insulin for control of diabetes. Antibiotics given according to the infective status of the patients. Patients were either completely treated, went under skin grafting or ended up with amputation were recorded.Results: Of 100 cases studied, youngest patient was 32 years and oldest was 80 years of age. Highest number of cases was found in the age group 61-70 years (30%). Of the 100 cases studied in this series 36 (36%) patient were having Wagner’s class 1 ulcer and 64 (64%) patient having class 2 ulcers. Of 100 cases, various surgical treatment given to the patients according to the ulcer. In that 65(65%) debridement, 20 (20%) Incision & drainage, 10 (10%) STG, 5 (5%) fasciotomy. Most of the patients were undergone basic surgical procedure which is debridement on the 7th day follow up, out of 100 cases 70 patients came for follow up. Out of 70, all patients having healing ulcer. Out of 70 patients, 15(21.43%) patients were underwent STG on 15th day and other 55 (71.57%) patients having healing ulcer advised daily dressing with follow up after 1 week. Out of 30 patients, 3 (10%) patients underwent amputation on 7th day of follow up. On the 15th day new 5 (16.67%) patients underwent amputations, so total number of amputation done till date was 8 (26.67%). On 21st day, new 7 (23.34%) patients were underwent amputations and total number of amputations till date were 15 (50%). On 30th day, new 15 (50%) patients underwent amputations.Conclusions: Foot ulceration in diabetic patients is a resource consuming, disabling morbidity that often is the first step towards lower extremity amputation. Prevention is the best treatment.

Flux Tube Model Signals for Baryon Correlations in Heavy Ion Collisions

The flux tube model offers a pictorial description of what happens during the deconfinement phase transition in QCD. The 3-point vertices of a flux tube network lead to formation of baryons upon hadronisation. Therefore, correlations in the baryon number distribution at the last scattering surface are related to the preceding pattern of the flux tube vertices, and provide a signature of the nearby deconfinement phase transition. I discuss the nature of the expected signal, which should be observable in heavy ion collisions at RHIC and LHC.Comment: LaTeX, 9 pages, 5 figures, (v2) Several arguments expanded for clarity, (v3) Minor typesetting changes, published versio