The lifecycle of the North Atlantic storm track

The North Atlantic eddy-driven jet exhibits latitudinal variability, with evidence of three preferred latitudinal locations: south, middle and north. Here we examine the drivers of this variability and the variability of the associated storm track. We investigate the changes in the storm track characteristics for the three jet locations, and propose a mechanism by which enhanced storm track activity, as measured by upstream heat flux, is responsible for cyclical downstream latitudinal shifts in the jet. This mechanism is based on a nonlinear oscillator relationship between the enhanced meridional temperature gradient (and thus baroclinicity) and the meridional high-frequency (periods of shorter than 10 days) eddy heat flux. Such oscillations in baroclinicity and heat flux induce variability in eddy anisotropy which is associated with the changes in the dominant type of wave breaking and a different latitudinal deflection of the jet. Our results suggest that high heat flux is conducive to a northward deflection of the jet, whereas low heat flux is conducive to a more zonal jet. This jet deflecting effect was found to operate most prominently downstream of the storm track maximum, while the storm track and the jet remain anchored at a fixed latitudinal location at the beginning of the storm track. These cyclical changes in storm track characteristics can be viewed as different stages of the storm track’s spatio-temporal lifecycle

Qualitative Analysis of Maternal Barriers and Perceptions to Participation in a Federal Supplemental Nutrition Program in Rural Appalachian North Carolina

Background: Little is known about barriers to and perceptions of participation in the in Women, Infants, and Children (WIC) program in rural Appalachia. Purpose: To gain a deeper understanding of maternal barriers and perceptions related to WIC participation in rural Appalachia Methods: Pregnant women and mothers were recruited in-person and via flyers from WIC offices in three counties in Appalachian North Carolina. Four semi-structured focus groups were conducted between May to July 2018. Each focus group was approximately 60 minutes long and included open-ended questions about the overall WIC experience in rural Appalachia. Focus groups were audio-recorded, transcribed verbatim, and content analysis of transcripts was performed by two trained researchers. Identified themes were discussed and consensus was reached by the researchers to generate final themes for four areas of interest: (1) most valued aspects of WIC program, (2) barriers to program participation and benefit redemption, (3) experiences during appointments, and (4) suggestions for improving experiences in program. Results: The most valued aspects of participation were financial benefits and support/resources provided by WIC staff. In contrast, lack of variety of WIC-approved foods and social stigma were perceived as major barriers to participation and redeeming benefits. Implications: This study contributes to a better understanding of the barriers and perceptions related to WIC participation in this geographically and culturally unique area of rural Appalachia. Findings are valuable for informing WIC state-agencies and policymakers whose efforts focus on the identification and development of effective recruitment and retention strategies for WIC-eligible families in rural Appalachia

Baroclinic adjustment and dissipative control of storm tracks

The steady-state response of a mid-latitude storm track to large-scale extratropical thermal forcing and eddy friction is investigated in a dry general circulation model with a zonally symmetric forcing. A two-way equilibration is found between the relative responses of the mean baroclinicity and baroclinic eddy intensity, whereby mean baroclinicity responds more strongly to eddy friction whereas eddy intensity responds more strongly to the thermal forcing of baroclinicity. These seemingly counter-intuitive responses are reconciled using the steady state of a predator-prey relationship between baroclinicity and eddy intensity. This relationship provides additional support for the well studied mechanism of baroclinic adjustment in the Earth’s atmosphere, as well as providing a new mechanism whereby eddy dissipation controls the large-scale thermal structure of a baroclinically unstable atmosphere. It is argued that these two mechanisms of baroclinic adjustment and dissipative control should be used in tandem when considering storm track equilibration

Melvin universe as a limit of the C-metric

It is demonstrated that the Melvin universe representing the spacetime with a strong 'homogeneous' electric field can by obtained from the spacetime of two accelerated charged black holes by a suitable limiting procedure. The behavior of various invariantly defined geometrical quantities in this limit is also studied.Comment: 5 pages, no figures [v2: two references added

Low-temperature UV photoluminescence of ion beam synthesized Si nanoclusters embedded in Si

Ultraviolet (UV) photoluminescence (PL) data taken on a double Au implanted Si matrix are reported. This has been studied over a wide temperature range of 28-220 K. At low temperature, the spectrum shows four peaks corresponding to a zero-phonon line (ZP

Exhaustive enumeration unveils clustering and freezing in random 3-SAT

We study geometrical properties of the complete set of solutions of the random 3-satisfiability problem. We show that even for moderate system sizes the number of clusters corresponds surprisingly well with the theoretic asymptotic prediction. We locate the freezing transition in the space of solutions which has been conjectured to be relevant in explaining the onset of computational hardness in random constraint satisfaction problems.Comment: 4 pages, 3 figure

No spin glass phase in ferromagnetic random-field random-temperature scalar Ginzburg-Landau model

Krzakala, Ricci-Tersenghi and Zdeborova have shown recently that the random field Ising model with non-negative interactions and arbitrary external magnetic field on an arbitrary lattice does not have a static spin glass phase. In this paper we generalize the proof to a soft scalar spin version of the Ising model: the Ginzburg-Landau model with random magnetic field and random temperature-parameter. We do so by proving that the spin glass susceptibility cannot diverge unless the ferromagnetic susceptibility does.Comment: 9 page

Associations of actigraphy‐assessed sleep variables with adiposity and serum cardiometabolic outcomes in emerging adults

SummaryThis study assessed associations of actigraphy‐assessed sleep with adiposity and serum cardiometabolic outcomes in emerging adults, and whether sex and race modified these associations. Data on 147 emerging adults (age = 19.4 ± 1.3 years; body mass index = 26.4 ± 7.0 kg m$^{−2}$; 59% female; 65% White) from RIGHT Track Health were used. Actigraphy‐based sleep measures included sleep duration, sleep efficiency, sleep timing midpoint, day‐to‐day sleep duration and sleep timing midpoint variability. Combined sleep duration and sleep timing behaviours were also derived (early‐bed/late‐rise, early‐bed/early‐rise, late‐bed/late‐rise, late‐bed/early‐rise). Outcomes included body mass index and BodPod‐assessed fat mass index, fasting serum leptin, C‐reactive protein, and homeostatic model assessment‐insulin resistance. Sleep duration was 5.4 h per night. We noted an inverse association between sleep duration and homeostatic model assessment‐insulin resistance. The early‐bed/early‐rise group had greater body mass index, C‐reactive protein and homeostatic model assessment‐insulin resistance compared with the early‐bed/late‐rise group (referent). Sex modified associations of sleep efficiency with C‐reactive protein; stratified results revealed positive association between sleep efficiency and C‐reactive protein in males, but not females. Race modified associations of sleep duration with body mass index and leptin, and of sleep duration variability with C‐reactive protein. Stratified analyses revealed inverse associations between sleep duration with body mass index and leptin in Black, multiracial/other race individuals only. Positive association between sleep duration variability and C‐reactive protein was noted in White individuals only. Shorter sleep duration, particularly when combined with earlier sleep timing, is associated with greater adiposity and serum cardiometabolic outcomes. Additional studies are needed to assess individual‐ and contextual‐level factors that may contribute to sex and race differences in sleep health and cardiometabolic risk in emerging adults

Shape Shifting Leads to Small-Molecule Allosteric Drug Discovery

SummaryEnzymes that regulate their activity by modulating an equilibrium of alternate, nonadditive, functionally distinct oligomeric assemblies (morpheeins) constitute a recently described mode of allostery. The oligomeric equilibrium for porphobilinogen synthase (PBGS) consists of high-activity octamers, low-activity hexamers, and two dimer conformations. A phylogenetically diverse allosteric site specific to hexamers is proposed as an inhibitor binding site. Inhibitor binding is predicted to draw the oligomeric equilibrium toward the low-activity hexamer. In silico docking enriched a selection from a small-molecule library for compounds predicted to bind to this allosteric site. In vitro testing of selected compounds identified one compound whose inhibition mechanism is species-specific conversion of PBGS octamers to hexamers. We propose that this strategy for inhibitor discovery can be applied to other proteins that use the morpheein model for allosteric regulation