An investigation of thundersnow environment differences between the Phoenix metropolitan area and Columbia, MO from an analytical and modeling perspective

Thundersnow (TSSN) is linked to increased snowfall intensity and accumulation totals within cyclones. Although rare, TSSN has been observed and studied across various regions of the U.S., although most attention has been given to the Midwest, Great Salt Lake and Great Lakes regions. On 20 February 2013 an upper level low with 500- hPa temperatures below 243 K tracked slowly eastward across the Southwestern U.S. and brought with it a wide swath of precipitation mostly in the form of rain over the low deserts. In the late afternoon, localized snow and graupel accumulations occurred in the Phoenix Metropolitan Area (PMA), with coincident reports of thunder. The Earth Network Total Lightning Network (ENTLN) confirmed lightning strikes in the area. This is an unusual event in that convective snowfall and snow accumulation at lower elevations of the PMA are extremely rare. Initial analysis of 3-km High Resolution Rapid Refresh (HRRR) output showed an isolated region of instability over the PMA (e.g., surface CAPE greater than 500 J kg-1 per the HRRR simulations) along with warm temperatures at the lower levels and the surface. This suggests that enough of an updraft was present to initiate charge separation, and that the event was likely surface based in nature. Temperatures likely cooled due to cooling effects of melting, evaporation and sublimation as precipitation fell, and allowed for a deepening of the 0[degrees]C isotherm and for frozen precipitation to reach the surface. This upper level storm continued eastward towards the central Great Plains on 21 February 2013, and produced more TSSN across the panhandles of Texas and Oklahoma, Kansas and Missouri, including Columbia, MO

The Multitude of Molecular Hydrogen Knots in the Helix Nebula

We present HST/NICMOS imaging of the H_2 2.12 \mu m emission in 5 fields in the Helix Nebula ranging in radial distance from 250-450" from the central star. The images reveal arcuate structures with their apexes pointing towards the central star. Comparison of these images with comparable resolution ground based images reveals that the molecular gas is more highly clumped than the ionized gas line tracers. From our images, we determine an average number density of knots in the molecular gas ranging from 162 knots/arcmin^2 in the denser regions to 18 knots/arcmin^2 in the lower density outer regions. Using this new number density, we estimate that the total number of knots in the Helix to be ~23,000 which is a factor of 6.5 larger than previous estimates. The total neutral gas mass in the Helix is 0.35 M_\odot assuming a mass of \~1.5x10^{-5} M_\odot for the individual knots. The H_2 intensity, 5-9x10^{-5} erg s^{-1} cm^{-2} sr^{-1}, remains relatively constant with projected distance from the central star suggesting a heating mechanism for the molecular gas that is distributed almost uniformly in the knots throughout the nebula. The temperature and H_2 2.12 \mu m intensity of the knots can be approximately explained by photodissociation regions (PDRs) in the individual knots; however, theoretical PDR models of PN under-predict the intensities of some knots by a factor of 10.Comment: 26 pages, 3 tables, 10 figures; AJ accepte

Signal Transduction and Pathogenic Modifications at the Melanocortin-4 Receptor: A Structural Perspective

The melanocortin-4 receptor (MC4R) can be endogenously activated by binding of melanocyte-stimulating hormones (MSH), which mediates anorexigenic effects. In contrast, the agouti-related peptide (AgRP) acts as an endogenous inverse agonist and suppresses ligand-independent basal signaling activity (orexigenic effects). Binding of ligands to MC4R leads to the activation of different G-protein subtypes or arrestin and concomitant signaling pathways. This receptor is a key protein in the hypothalamic regulation of food intake and energy expenditure and naturally-occurring inactivating MC4R variants are the most frequent cause of monogenic obesity. In general, obesity is a growing problem on a global scale and is of social, medical, and economic relevance. A significant goal is to develop optimized pharmacological tools targeting MC4R without adverse effects. To date, this has not been achieved because of inter alia non-selective ligands across the five functionally different MCR subtypes (MC1-5R). This motivates further investigation of (i) the three-dimensional MC4R structure, (ii) binding mechanisms of various ligands, and (iii) the molecular transfer process of signal transduction, with the aim of understanding how structural features are linked with functional-physiological aspects. Unfortunately, experimentally elucidated structural information is not yet available for theMC receptors, a group of class A G-protein coupled receptors (GPCRs). We, therefore, generated MC4R homology models and complexes with interacting partners to describe approximate structural properties associated with signaling mechanisms. In addition, molecular insights from pathogenic mutations were incorporated to discriminate more precisely their individual malfunction of the signal transfer mechanism

The Nature and Origin of Molecular Knots in Planetary Nebulae

doi:10.1063/1.2146252Planetary Nebulae (PNe) are major contributors to the enrichment of the interstellar medium (ISM). Knots and filaments in the ionized gas images of PNe are common, if not ubiquitous. Additionally, it has been shown that molecular gas exists inside dense condensations within the ionized regions. The origins of these clumps are not known, though the suggested formation mechanisms fall into two main scenarios: (1) they form during the AGB phase; (2) they form as a result of the onset of the PN phase as the fast wind ploughs into the slower moving AGB wind. The currently favored model is that the knots are formed by the onset of the PN phase and then sculpted as the ionizing radiation penetrates deeper into the circumstellar envelope. We present preliminary results of a study which compares the morphologies of molecular and ionized gas emission in several PNe, covering a range of ages.This work was supported by several funding agencies: SE and AS were supported by HST-AR- 10686, and by the Research Council of University of Missouri - Columbia. MM and PM were supported in part by HST-GO-01041 and by the internal STScI funds, DDRFD0001.82319. Support for Program numbers HST-AR-10686 and HST-GO-01041 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555

Broad-Range 16S rRNA Gene Polymerase Chain Reaction for Diagnosis of Culture-Negative Bacterial Infections

This study defines the role of 16S ribosomal RNA (rRNA) gene polymerase chain reaction (PCR) for diagnosis of culture-negative bacterial infections. Our data show that 16S rRNA PCR is particularly valuable for identification of pathogens in patients pretreated with antibiotic

Long-Term Safety of Topical Bacteriophage Application to the Frontal Sinus Region

Copyright © 2017 Drilling, Ooi, Miljkovic, James, Speck, Vreugde, Clark and Wormald. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.Background: Staphylococcus aureus biofilms contribute negatively to a number of chronic conditions, including chronic rhinosinusitis (CRS). With the inherent tolerance of biofilm-bound bacteria to antibiotics and the global problem of bacterial antibiotic resistance, the need to develop novel therapeutics is paramount. Phage therapy has previously shown promise in treating sinonasal S. aureus biofilms. Methods: This study investigates the long term (20 days) safety of topical sinonasal flushes with bacteriophage suspensions. The bacteriophage cocktail NOV012 against S. aureus selected for this work contains two highly characterized and different phages, P68 and K710. Host range was assessed against S. aureus strains isolated from CRS patients using agar spot tests. NOV012 was applied topically to the frontal sinus region of sheep, twice daily for 20 days. General sheep wellbeing, mucosal structural changes and inflammatory load were assessed to determine safety of NOV012 application. Results: NOV012 could lyse 52/61 (85%) of a panel of locally derived CRS clinical isolates. Application of NOV012 to the frontal sinuses of sheep for 20 days was found to be safe, with no observed inflammatory infiltration or tissue damage within the sinus mucosa. Conclusion: NOV012 cocktail appears safe to apply for extended periods to sheep sinuses and it could infect and lyse a wide range of S. aureus CRS clinical isolates. This indicates that phage therapy has strong potential as a treatment for chronic bacterial rhinosinusitis

Energy Efficient Frequency Scaling and Scheduling for Malleable Tasks

We give an efficient algorithm for solving the following scheduling problem to optimality: Assign n jobs to m processors such that they all meet a common deadline T and energy consumption is minimized by appropriately controlling the clock frequencies of the processors. Jobs are malleable, i.e., their amount of parallelism can be flexibly adapted. In contrast to previous work on energy efficient scheduling we allow more realistic energy consumption functions including a minimum and maximum clock frequency and a linear term in energy consumption. We need certain assumptions on the speedup function of the jobs that we show to apply for a large class of practically occurring functions