Bioluminescent signals spatially amplified by wavelength-specific diffusion through the shell of a marine snail

Some living organisms produce visible light (bioluminescence) for intra- or interspecific visual communication. Here, we describe a remarkable bioluminescent adaptation in the marine snail Hinea brasiliana. This species produces a luminous display in response to mechanical stimulation caused by encounters with other motile organisms. The light is produced from discrete areas on the snail's body beneath the snail's shell, and must thus overcome this structural barrier to be viewed by an external receiver. The diffusion and transmission efficiency of the shell is greater than a commercial diffuser reference material. Most strikingly, the shell, although opaque and pigmented, selectively diffuses the blue-green wavelength of the species bioluminescence. This diffusion generates a luminous display that is enlarged relative to the original light source. This unusual shell thus allows spatially amplified outward transmission of light communication signals from the snail, while allowing the animal to remain safely inside its hard protective shell

Effects of irradiation on the cowpea weevil (Callosobruchus maculates F.) and moisture sorption isotherm of cowpea seed (Vigna unguiculata L. Walp)

Cowpeas during storage may be attacked by a number of biological agents (microorganisms, rodents, and insects) which results in losses in the quality and quantity of the stored seeds. One of the means of reducing these losses is through the application of radiation processing. The aim of this study was to determine the effects of gamma irradiation on a major storage insect pest, Callosobruchus maculatus F. and on moisture sorption isotherms of cowpea seeds in storage. The cowpeas were infested with adults C. maculatus and then irradiated at doses of 0.0, 0.25, 0.5, 0.75, 1.0 and 1.5 (kGy) at a dose rate of 1.074 kGyhr-1. Samples were stored for 1 month under controlled temperature (27.3-30 oC) and humidity (70-85 %) during which counting of the insects was done every 48 hours and those alive or dead noted. Moisture sorption isotherms of the cowpea samples were equally determined by establishing equilibrium relative humidity (ERH) of 55, 65, 75, 85 and 95 % using a formulation of glycerol-water mixture at temperature of 30+-1 and the weight (loss or gain) of the samples was determined every 2 days. Irradiation at a dose of 0.25 kGy killed the C. maculatus within eight days and therefore 0.25 kGy would be economically beneficial as a control dose. There was significant difference (p is less than 0.05) in the percent mortality between the irradiated and the non-irradiated weevils, and the percent mortality increased with increase in the radiation dose. At moisture content of 14 % the irradiated cowpea samples were safely stored for one month at an equilibrium relative humidity of 60-75 % at a temperature of 29+-2 oC

X-ray photoemission study of NiS_{2-x}Se_x (x = 0.0 - 1.2)

Electronic structure of NiS_{2-x}Se_x system has been investigated for various compositions (x) using x-ray photoemission spectroscopy. An analysis of the core level as well as the valence band spectra of NiS_2 in conjunction with many-body cluster calculations provides a quantitative description of the electronic structure of this compound. With increasing Se content, the on-site Coulomb correlation strength (U) does not change, while the band width W of the system increases, driving the system from a covalent insulating state to a pd-metallic state.Comment: 19 pages, 6 figures, To appear in Phys. Rev. B, 200

Tackling antimicrobial resistance in lower urinary tract infections : treatment options

Urinary tract infections (UTIs) are among the most common infectious diseases occurring in either the community or healthcare settings. A wide variety of bacteria are responsible for causing UTIs, however extra-intestinal pathogenic E. coli or ExPEC) remains the most common etiological agent. Since 2000, resistance to antibiotics emerged globally among ExPEC and is causing delays in appropriate therapy with subsequent increased morbidity and mortality. For patients with acute uncomplicated lower UTIs, nitrofurantoin, trimethoprim-sulfamethoxazole, fosfomycin or pivmecillinam should be prescribed for a 1-5 day course depending on the agent used. Single-dose fosfomycin is an excellent option for uncomplicated lower UTIs and has had similar clinical and/or bacteriological efficacy for 3- or 7-day regimens for alternate agents (i.e., ciprofloxacin, norfloxacin, cotrimoxazole or nitrofurantoin). The aim of this review article is to provide an overview on the definitions, etiology, treatment guidelines (including agents for infections due to antimicrobial resistant bacteria) of lower UTIs and to highlight recent aspects on antimicrobial resistance of ExPEC.In part by a research grant from Calgary Laboratory Services (#10009392).http://www.tandfonline.com/loi/ierz202017-07-30hb2016Medical Microbiolog

A Multi-US City Assessment of Awareness and Uptake of Pre-exposure Prophylaxis (PrEP) for HIV Prevention Among Black Men and Transgender Women Who Have Sex with Men

The HIV epidemic among Black men and transgender women who have sex with men (BMTW) demands an urgent public health response. HIV point prevalence among this population ranges from 25 to 43%—a rate far exceeding any other group. Pre-exposure prophylaxis (PrEP) for HIV prevention is a very promising prevention tool; however, its full potential to slow the epidemic has yet to be realized. For the current study, random time-location sampling at Black Gay Pride Events was used to collect data from N = 1274 BMTW, from five US cities, reporting HIV-negative/unknown status. In-field HIV testing was also provided to participants. Participants were assessed on awareness and use of PrEP, health care factors, HIV testing history, psychosocial variables, and sex behaviors. About one third of participants were aware of PrEP (39%), and a small percentage of participants were users of PrEP (4.6%). In multivariable analyses, being in a relationship, testing for HIV in the past 6 months, and others being aware of one’s sexuality were positively associated with PrEP awareness. Higher levels of internalized homophobia and greater numbers of female sex partners were positively associated with PrEP use, while education and condom use were negatively associated. Based on study findings, messaging and uptake of PrEP needs greater expansion and requires novel approaches for scale-up. Improving linkage to HIV testing services is likely critical for engaging BMTW with PrEP. The potential for PrEP to slow the HIV epidemic is high; however, we must strengthen efforts to ensure universal availability and uptake

Constraining the Kahler Moduli in the Heterotic Standard Model

Phenomenological implications of the volume of the Calabi-Yau threefolds on the hidden and observable M-theory boundaries, together with slope stability of their corresponding vector bundles, constrain the set of Kaehler moduli which give rise to realistic compactifications of the strongly coupled heterotic string. When vector bundles are constructed using extensions, we provide simple rules to determine lower and upper bounds to the region of the Kaehler moduli space where such compactifications can exist. We show how small these regions can be, working out in full detail the case of the recently proposed Heterotic Standard Model. More explicitely, we exhibit Kaehler classes in these regions for which the visible vector bundle is stable. On the other hand, there is no polarization for which the hidden bundle is stable.Comment: 28 pages, harvmac. Exposition improved, references and one figure added, minor correction

Simultaneous interval regression for K-nearest neighbor

International audienceIn some regression problems, it may be more reasonable to predict intervals rather than precise values. We are interested in finding intervals which simultaneously for all input instances x ∈X contain a β proportion of the response values. We name this problem simultaneous interval regression. This is similar to simultaneous tolerance intervals for regression with a high confidence level γ ≈ 1 and several authors have already treated this problem for linear regression. Such intervals could be seen as a form of confidence envelop for the prediction variable given any value of predictor variables in their domain. Tolerance intervals and simultaneous tolerance intervals have not yet been treated for the K-nearest neighbor (KNN) regression method. The goal of this paper is to consider the simultaneous interval regression problem for KNN and this is done without the homoscedasticity assumption. In this scope, we propose a new interval regression method based on KNN which takes advantage of tolerance intervals in order to choose, for each instance, the value of the hyper-parameter K which will be a good trade-off between the precision and the uncertainty due to the limited sample size of the neighborhood around each instance. In the experiment part, our proposed interval construction method is compared with a more conventional interval approximation method on six benchmark regression data sets

Crossover in the nature of the metallic phases in the perovskite-type RNiO_3

We have measured the photoemission spectra of Nd$_{1-x}$Sm$_{x}$NiO$_{3}$, where the metal-insulator transition and the N\'{e}el ordering occur at the same temperature for $x \lesssim 0.4$ and the metal-insulator transition temperature ($T_{MI}$) is higher than the N\'{e}el temperature for $x \gtrsim 0.4$. For $x \le 0.4$, the spectral intensity at the Fermi level is high in the metallic phase above $T_{MI}$ and gradually decreases with cooling in the insulating phase below $T_{MI}$ while for $x > 0.4$ it shows a pseudogap-like behavior above $T_{MI}$ and further diminishes below $T_{MI}$. The results clearly establish that there is a sharp change in the nature of the electronic correlations in the middle ($x \sim 0.4$) of the metallic phase of the $R$NiO$_3$ system.Comment: 4 pages, 4 figure, submitted to Phys. Rev.

Running Backwards: Consequences of Current HIV Incidence Rates for the Next Generation of Black MSM in the United States

Black men who have sex with men (MSM) in the United States are disproportionately impacted by HIV. To better understand this public health problem, we reviewed the literature to calculate an estimate of HIV incidence among Black MSM. We used this rate to model HIV prevalence over time within a simulated cohort, which we subsequently compared to prevalence from community-based samples. We searched all databases accessible through PubMed, and Conference on Retroviruses and Opportunistic Infections abstracts for HIV incidence estimates among Black MSM. Summary HIV incidence rates and 95 % confidence intervals (CIs) were calculated using random effects models. Using the average incidence rate, we modeled HIV prevalence within a simulated cohort of Black MSM (who were all HIV-negative at the start) from ages 18 through 40. Based on five incidence rates totaling 2898 Black MSM, the weighted mean incidence was 4.16 % per year (95 % CI 2.76–5.56). Using this annual incidence rate, our model predicted that 39.94 % of Black MSM within the simulated cohort would be HIV-positive by age 30, and 60.73 % by 40. Projections were similar to HIV prevalence found in community-based samples of Black MSM. High HIV prevalence will persist across the life-course among Black MSM, unless effective prevention and treatment efforts are increased to substantially reduce HIV transmission among this underserved and marginalized population