Modeling Tick-Borne Diseases in the Virginia and Middle Peninsula

Tick-borne diseases are on the rise, causing concern for human health as ticks continue to expand both in range and numbers. This study sought to assess the prevalence of two tick-borne diseases on the Virginia and Middle Peninsula and to identify the variables that explain their distributions. The two disease-causing bacteria, Ehrlichia chaffeensis and Rickettsia parkeri, are both transmitted by the lone star tick, the most common human-biting tick in the study area and in the southeastern United States. Nymph ticks were collected at 122 random sites in southeastern Virginia and DNA was extracted from the pooled ticks from each site. Bacterial DNA was detected using both endpoint PCR and Taqman qPCR to compare sensitivities of the assays. The two methods detected E. chaffeensis at 48.4% and 52.3% of sites, respectively, while R. parkeri was not detected at any sites based on Taqman PCR. We developed two logistic regressions models, based on each PCR method, which were spatially applied to develop spatial models of probability of E. chaffeensis presence, to determine biotic and abiotic variables explaining heterogeneity in disease occurrence. We selected candidate sets of models based on the information-theoretic approach. The variables identified for both sets of models were linked to white-tailed deer browsing and space use, while tick counts and time of year were not included in the final candidate models. These results suggest that the white-tailed deer, the primary host of lone star ticks and the only known reservoir host of E. chaffeensis, is the most important predictor of E. chaffeensis distribution

Submerged culture production of 5\u27-phosphodiesterase by streptomyces albus

The flavor enhancing properties of certain 5\u27-ribonucleotides have been known for some time. In 1913, Kodama (20)* reported on the seasoning effect of inosine-5-phosphate (5’-IMP). This compound was also identified as one of the important beef flavor precursors by Batzer and LandMann (3). Kuninaka (21) found that guanosine-5-phosphate (5\u27-GMP) and xanthine-5-phosphate (5\u27-XMP) also had a flavoring effect similar to 5’-IMP. Snake venom (16) and intestional mucosa (6) were known as sources of 5\u27-phosphodiesterase capable of hydrolyzing the phosphate ester link-ages of ribonucleic acid (RNA) to produce 5\u27-ribonucleotides. Recently, it has been discovered that many microorganisms (22,23,25,26,27) produce 5\u27-phosphodiesterase. Therefore, it has become possible to use certain microorganisms as sources of 5\u27-phosphodiesterase for use in production of 5\u27-ribonucleotides from RNA. With this in mind, a strain of Strep-tomyces albus, known to produce 5\u27-phosphodiesterase in submerged cul-ture (23), was studied to determine the effects of various factors (pH, temperature, and nutrients) on growth and enzyme production and to scale up production from laboratory to pilot-plant quantity

Observation of vortices and hidden pseudogap from scanning tunneling spectroscopic studies of electron-doped cuprate superconductor Sr0.9La0.1CuO2Sr_{0.9}La_{0.1}CuO_2

We present the first demonstration of vortices in an electron-type cuprate superconductor, the highest $T_c$ (= 43 K) electron-type cuprate $Sr_{0.9}La_{0.1}CuO_2$. Our spatially resolved quasiparticle tunneling spectra reveal a hidden low-energy pseudogap inside the vortex core and unconventional spectral evolution with temperature and magnetic field. These results cannot be easily explained by the scenario of pure superconductivity in the ground state of high-$T_c$ superconductivity.Comment: 6 pages, 4 figures. Two new graphs have been added into Figure 2. Accepted for publication in Europhysics Letters. Corresponding author: Nai-Chang Yeh (E-mail: [email protected]

On the methanol emission detection in the TW Hya disc: the role of grain surface chemistry and non-LTE excitation

The recent detection of gas-phase methanol (CH$_3$OH) lines in the disc of TW Hya by Walsh et al. provided the first observational constraints on the complex O-bearing organic content in protoplanetary discs. The emission has a ring-like morphology, with a peak at $\sim 30-50$ au and an inferred column density of $\sim 3-6\times10^{12}$ cm$^{-2}$. A low CH$_3$OH fractional abundance of $\sim 0.3-4\times 10^{-11}$ (with respect to H$_2$) is derived, depending on the assumed vertical location of the CH$_3$OH molecular layer. In this study, we use a thermo-chemical model of the TW Hya disc, coupled with the ALCHEMIC gas-grain chemical model, assuming laboratory-motivated, fast diffusivities of the surface molecules to interpret the CH$_3$OH detection. Based on this disc model, we performed radiative transfer calculations with the LIME code and simulations of the observations with the CASA simulator. We found that our model allows to reproduce the observations well. The CH$_3$OH emission in our model appears as a ring with radius of $\sim60$ au. Synthetic and observed line flux densities are equal within the rms noise level of observations. The synthetic CH$_3$OH spectra calculated assuming local thermodynamic equilibrium (LTE) can differ by up to a factor of 3.5 from the non-LTE spectra. For the strongest lines, the differences between LTE and non-LTE flux densities are very small and practically negligible. Variations in the diffusivity of the surface molecules can lead to variations of the CH$_3$OH abundance and, therefore, line flux densities by an order of magnitude.Comment: Accepted for publication in MNRAS, 8 pages, 8 figure