Muon spin rotation study of the topological superconductor SrxBi2Se3

We report transverse-field (TF) muon spin rotation experiments on single crystals of the topological superconductor Sr$_x$Bi$_2$Se$_3$ with nominal concentrations $x=0.15$ and $0.18$ ($T_c \sim 3$ K). The TF spectra ($B= 10$ mT), measured after cooling to below $T_c$ in field, did not show any additional damping of the muon precession signal due to the flux line lattice within the experimental uncertainty. This puts a lower bound on the magnetic penetration depth $\lambda \geq 2.3 ~\mu$m. However, when we induce disorder in the vortex lattice by changing the magnetic field below $T_c$ a sizeable damping rate is obtained for $T \rightarrow 0$. The data provide microscopic evidence for a superconducting volume fraction of $\sim 70~ \%$ in the $x=0.18$ crystal and thus bulk superconductivity.Comment: 6 pages, includes 4 figure

Instability of an idealized tidal mixing front : symmetric instabilities and frictional effects

Author Posting. © Sears Foundation for Marine Research, 2013. This article is posted here by permission of Sears Foundation for Marine Research for personal use, not for redistribution. The definitive version was published in Journal of Marine Research 71 (2013): 425-450, doi:10.1357/002224013812587582.Finite amplitude instability of an idealized tidal mixing front is considered for cases where there is an active symmetric instability during the early stages of evolution. This can happen either when the initial front is sharp, or when a bottom stress leads to a well-mixed bottom boundary layer under the front. In either case, there is an initial phase, several days long, of slantwise convection, after which a much more energetic and spatially distributed baroclinic or barotropic instability dominates. The presence of an initial symmetrically unstable phase has no obvious effect on the subsequent eddy evolution. Bottom friction does lead to a slower growth rate for baroclinic instabilities, a lower eddy kinetic energy level, and (through stratified spindown) a tendency for flows to be more nearly surface intensified. The surface intensification means that the evolving eddy field cannot proceed toward a barotropic state, and so the horizontal eddy scale is also constrained. Thus, the finite-amplitude inverse cascade is strongly affected by the presence of a bottom stress. Scalings are derived for the frictionally corrected eddy kinetic energy and lateral mixing coefficient. The results, in terms of frictional effects on eddy structure and energy, appear to be valid beyond just the tidal mixing frontal problem.Support from the National Science Foundation, Physical Oceanography program, is gratefully acknowledged (Grant OCE-1059632)

Anatomy and physiology of cisternostomy

Cisternostomy is defined as opening the basal cisterns to atmospheric pressure. This technique helps to reduce the intracranial pressure in severe head trauma as well as other conditions when the so-called sudden "brain swelling" troubles the surgeon. We elaborated the surgical anatomy of this procedure as well as the proposed physiology of how cisternostomy works. This novel technique may change the current trends in neurosurgery

The effect of distance on observed mortality, childhood pneumonia and vaccine efficacy in rural Gambia.

We investigated whether straight-line distance from residential compounds to healthcare facilities influenced mortality, the incidence of pneumonia and vaccine efficacy against pneumonia in rural Gambia. Clinical surveillance for pneumonia was conducted on 6938 children living in the catchment areas of the two largest healthcare facilities. Deaths were monitored by three-monthly home visits. Children living >5 km from the two largest healthcare facilities had a 2·78 [95% confidence interval (CI) 1·74-4·43] times higher risk of all-cause mortality compared to children living within 2 km of these facilities. The observed rate of clinical and radiological pneumonia was lower in children living >5 km from these facilities compared to those living within 2 km [rate ratios 0·65 (95% CI 0·57-0·73) and 0·74 (95% CI 0·55-0·98), respectively]. There was no association between distance and estimated pneumococcal vaccine efficacy. Geographical access to healthcare services is an important determinant of survival and pneumonia in children in rural Gambia

Current understanding on venous leg ulcer

Venous leg ulcer (VLU) or stasis ulcer is a relatively common, chronic and recurring problem. Besides being costly to the health-care system, it significantly impairs the quality of life of the patients. Nearly 1% of adults and 3.6% of older patients are reported to suffer from this chronic condition. Chronic venous insufficiency is considered to be the predominant cause of VLU. The most recent theories associate the pathogenesis of venous ulcer with microcirculatory abnormalities and generation of an inflammatory response. The pharmacological treatment for VLU is based on the pathogenesis and often includes diosmin, pentoxifylline, diuretics as well as antibiotics and the non-pharmacological treatment like compression and skin grafting. VLU has a high rate of recurrence and requires self-care to avoid relapse. Treatment of VLU should always focus for complete treatment, and improve quality of life for patients along with minimum relapse. In recent years novel therapeutic approaches for venous ulcers have offered valuable tools for the management of patients with this disorder

Inducible nitric oxide synthase mediates DNA double strand breaks in Human T-Cell Leukemia Virus Type 1-induced leukemia/lymphoma

BACKGROUND: Adult T-cell leukemia/lymphoma (ATLL) is an aggressive and fatal malignancy of CD4(+) T-lymphocytes infected by the Human T-Cell Virus Type 1 (HTLV-1). The molecular mechanisms of transformation in ATLL have not been fully elucidated. However, genomic instability and cumulative DNA damage during the long period of latency is believed to be essential for HTLV-1 induced leukemogenesis. In addition, constitutive activation of the NF-κB pathway was found to be a critical determinant for transformation. Whether a connection exists between NF-κB activation and accumulation of DNA damage is not clear. We recently found that the HTLV-1 viral oncoprotein, Tax, the activator of the NF-κB pathway, induces DNA double strand breaks (DSBs). RESULTS: Here, we investigated whether any of the NF-κB target genes are critical in inducing DSBs. Of note, we found that inducible nitric oxide synthase (iNOS) that catalyzes the production of nitric oxide (NO) in macrophages, neutrophils and T-cells is over expressed in HTLV-1 infected and Tax-expressing cells. Interestingly, we show that in HTLV-1 infected cells, iNOS expression is Tax-dependent and specifically requires the activation of the classical NF-κB and JAK/STAT pathways. A dramatic reduction of DSBs was observed when NO production was inhibited, indicating that Tax induces DSBs through the activation of NO synthesis. CONCLUSIONS: Determination of the impact of NO on HTLV-1-induced leukemogenesis opens a new area for treatment or prevention of ATLL and perhaps other cancers in which NO is produced

Disorder-driven electronic localization and phase separation in superconducting Fe1+yTe0.5Se0.5 single crystals

We have investigated the influence of Fe-excess on the electrical transport and magnetism of Fe1+yTe0.5Se0.5 (y=0.04 and 0.09) single crystals. Both compositions exhibit resistively determined superconducting transitions (Tc) with an onset temperature of about 15 K. From the width of the superconducting transition and the magnitude of the lower critical field Hc1, it is inferred that excess of Fe suppresses superconductivity. The linear and non-linear responses of the ac-susceptibility show that the superconducting state for these compositions is inhomogeneous. A possible origin of this phase separation is a magnetic coupling between Fe-excess occupying interstitial sites in the chalcogen planes and those in the Fe-square lattice. The temperature derivative of the resistivity drho/dT in the temperature range Tc < T < Ta with Ta being the temperature of a magnetic anomaly, changes from positive to negative with increasing Fe. A log 1/T divergence of the resistivity above Tc in the sample with higher amount of Fe suggests a disorder driven electronic localization.Comment: 7 page

Recognition of Everyday Activities through Wearable Sensors and Machine Learning

Over the past several years, the use of wearable devices has increased dramatically, primarily for fitness monitoring, largely due to their greater sensor reliability, increased functionality, smaller size, increased ease of use, and greater affordability. These devices have helped many people of all ages live healthier lives and achieve their personal fitness goals, as they are able to see quantifiable and graphical results of their efforts every step of the way (i.e. in real-time). Yet, while these device systems work well within the fitness domain, they have yet to achieve a convincing level of functionality in the larger domain of healthcare. As an example, according to the Alzheimer’s Association, there are currently approximately 5.5 million Americans with Alzheimer’s Disease and approximately 5.3 million of them are over the age of 65, comprising 10% of this age group in the U.S. The economic toll of this disease is estimated to be around $259 billion. By 2050 the number of Americans with Alzheimer’s disease is predicted to reach around 16 million with an economic toll of over$1 trillion. There are other prevalent and chronic health conditions that are critically important to monitor, such as diabetes, complications from obesity, congestive heart failure, and chronic obstructive pulmonary disease (COPD) among others. The goal of this research is to explore and develop accurate and quantifiable sensing and machine learning techniques for eventual real-time health monitoring by wearable device systems. To that end, a two-tier recognition system is presented that is designed to identify health activities in a naturalistic setting based on accelerometer data of common activities. In Tier I a traditional activity recognition approach is employed to classify short windows of data, while in Tier II these classified windows are grouped to identify instances of a specific activity. Everyday activities that were explored in this research include brushing one’s teeth, combing one’s hair, scratching one’s chin, washing one’s hands, taking medication, and drinking. Results show that an F-measure of 0.83 is achievable when identifying these activities from each other and an F-measure of 0.82 is achievable when identifying instances of brushing teeth over the course of a day