Continuous phase amplification with a Sagnac interferometer

We describe a weak value inspired phase amplification technique in a Sagnac interferometer. We monitor the relative phase between two paths of a slightly misaligned interferometer by measuring the average position of a split-Gaussian mode in the dark port. Although we monitor only the dark port, we show that the signal varies linearly with phase and that we can obtain similar sensitivity to balanced homodyne detection. We derive the source of the amplification both with classical wave optics and as an inverse weak value.Comment: 5 pages, 4 figures, previously submitted for publicatio

A LOFAR mini-survey for low-frequency radio emission from the nearest brown dwarfs

We have conducted a mini-survey for low-frequency radio emission from some of the closest brown dwarfs to the Sun with rapid rotation rates: SIMP J013656.5 +093347, WISEPC 150649.97+702736.0, and WISEPA J174124.26+255319.5.We have placed robust 3s upper limits on the flux density in the 111 – 169 MHz frequency range for these targets: WISE 1506: < 0:72 mJy; WISE 1741: < 0:87 mJy; SIMP 0136: < 0:66 mJy. At 8 hours of integration per target to achieve these limits, we find that systematic and detailed study of this class of object at LOFAR frequencies will require a substantial dedication of resources

Atom loss from Bose-Einstein condensates due to Feshbach resonance

In recent experiments on Na Bose-Einstein condensates [S. Inouye et al, Nature 392, 151 (1998); J. Stenger et al, Phys. Rev. Lett. 82, 2422 (1999)], large loss rates were observed when a time-varying magnetic field was used to tune a molecular Feshbach resonance state near the state of pairs of atoms belonging to the condensate many-body wavefunction. A mechanism is offered here to account for the observed losses, based on the deactivation of the resonant molecular state by interaction with a third condensate atom.Comment: LaTeX, 4 pages, 4 PostScript figures, uses REVTeX and psfig, submitted to Physical Review A, Rapid Communication

Solution of the Unanimity Rule on exponential, uniform and scalefree networks: A simple model for biodiversity collapse in foodwebs

We solve the Unanimity Rule on networks with exponential, uniform and scalefree degree distributions. In particular we arrive at equations relating the asymptotic number of nodes in one of two states to the initial fraction of nodes in this state. The solutions for exponential and uniform networks are exact, the approximation for the scalefree case is in perfect agreement with simulation results. We use these solutions to provide a theoretical understanding for experimental data on biodiversity loss in foodwebs, which is available for the three network types discussed. The model allows in principle to estimate the critical value of species that have to be removed from the system to induce its complete collapse.Comment: 4 pages, 3 fig

Statistical Analysis of Airport Network of China

Through the study of airport network of China (ANC), composed of 128 airports (nodes) and 1165 flights (edges), we show the topological structure of ANC conveys two characteristics of small worlds, a short average path length (2.067) and a high degree of clustering (0.733). The cumulative degree distributions of both directed and undirected ANC obey two-regime power laws with different exponents, i.e., the so-called Double Pareto Law. In-degrees and out-degrees of each airport have positive correlations, whereas the undirected degrees of adjacent airports have significant linear anticorrelations. It is demonstrated both weekly and daily cumulative distributions of flight weights (frequencies) of ANC have power-law tails. Besides, the weight of any given flight is proportional to the degrees of both airports at the two ends of that flight. It is also shown the diameter of each sub-cluster (consisting of an airport and all those airports to which it is linked) is inversely proportional to its density of connectivity. Efficiency of ANC and of its sub-clusters are measured through a simple definition. In terms of that, the efficiency of ANC's sub-clusters increases as the density of connectivity does. ANC is found to have an efficiency of 0.484.Comment: 6 Pages, 5 figure

Diabetes Related Distress and Co-Occurrence with Depressive Symptoms in Urban Low-Income African American and Hispanic/Latinx Adults with Type 2 Diabetes

Introduction. Burden of diabetes in the U.S. is greater in racial-ethnic minority populations than non-Hispanic Whites. Depression and diabetes-related distress (DRD) are recognized as relatively common and important psychosocial areas to address in people living with diabetes. Limited research in the U.S. has focused on DRD in racial-ethnic minority populations. The purpose of this study is to describe patterns of DRD and co-occurrence with depressive symptoms in urban low-income African American and Hispanic/Latinx adults with type 2 Diabetes Mellitus (T2DM). Method. We examined the baseline data collected for a randomized clinical trial (RCT) studying the impact of a culturally tailored diabetes self-care intervention. Individuals with T2DM who self-identified as African American or Hispanic/Latinx were recruited from Federally Qualified Health Centers (FQHCs). Measurement scales included the Patient Health Questionnaire (PHQ-9) and Diabetes Distress Scale (DDS). Participants were categorized into four groups based on the PHQ-9 and DDS: high distress (without probable clinical depression), probable clinical depression (without high distress), both high distress and probable depression, or neither high distress nor probable depression. Baseline variables were summarized by sex, age and racial-ethnic group. Analyses included independent sample t-tests, Chi-square tests, and one-way Analysis of Variance (ANOVA). Results. The study sample included 247 participants with 118 (47.8%) Hispanic/Latinx and 129 (52.2%) African American adults with T2DM. The mean age was 52.9 years (SD=12.2) and 68.0% were female. Based on PHQ-9 scores, 51.4% had none to minimal, 23.5% mild, and 25.1% moderate-severe depressive symptomatology. Based on the DDS, 37.7% had little to no DRD, 27.1% moderate, and 35.2% high DRD. There was not a statistically significant relationship between sex and depression or DRD levels. There was not a statistically significant difference between age and depression; however, there was a statistically significant difference between age and DRD (p=.002). When examining the co-occurrence of DRD and depression, over half of the participants did not experience high distress nor probable clinical depression (57.5%), 17.8% experienced both high distress and depression, 17.4% experienced high distress without depression, and 7.3% experienced depression without distress. There was no statistically significant relationship found between sex and co-occurrence groups; however, there was a statistically significant difference for age (p=.003). Discussion. A substantial proportion of individuals from both racial-ethnic groups experienced high DRD and/or probable clinical depression with some differences for age. Patterns found for specific DRD areas and co-occurrence of DRD and depressive symptoms can help clinicians better understand and address these challenges

Continuous Phase Amplification with a Sagnac Interferometer

We describe a phase-amplification technique using a Sagnac interferometer. We monitor the relative phase between two paths of a precisely misaligned interferometer by measuring the average position of a split-Gaussian mode in the dark port. Although we monitor only the dark port, we show that the signal varies linearly with phase and that we can obtain similar sensitivity to balanced homodyne detection. We derive the source of the amplification using classical wave optics

Spectropolarimetry of SN 2011dh in M51: geometric insights on a Type IIb supernova progenitor and explosion

We present seven epochs of spectropolarimetry of the Type IIb supernova (SN) 2011dh in M51, spanning 86 days of its evolution. The first epoch was obtained 9 days after the explosion, when the photosphere was still in the depleted hydrogen layer of the stripped-envelope progenitor. Continuum polarization is securely detected at the level of P~0.5% through day 14 and appears to diminish by day 30, which is different from the prevailing trends suggested by studies of other core-collapse SNe. Time-variable modulations in P and position angle are detected across P-Cygni line features. H-alpha and HeI polarization peak after 30 days and exhibit position angles roughly aligned with the earlier continuum, while OI and CaII appear to be geometrically distinct. We discuss several possibilities to explain the evolution of the continuum and line polarization, including the potential effects of a tidally deformed progenitor star, aspherical radioactive heating by fast-rising plumes of Ni-56 from the core, oblique shock breakout, or scattering by circumstellar material. While these possibilities are plausible and guided by theoretical expectations, they are not unique solutions to the data. The construction of more detailed hydrodynamic and radiative-transfer models that incorporate complex aspherical geometries will be required to further elucidate the nature of the polarized radiation from SN 2011dh and other Type IIb supernovae.Comment: Post-proof edit. Accepted to MNRAS 2015 Aug 1