685 research outputs found
How Did Participating In a Prenatal Nutrition and Exercise Program Influence Postpartum Experiences During COVID-19?
International Journal of Exercise Science 16(3): 1-11, 2023. Lifestyle interventions focusing on prenatal physical activity (PA) and healthy nutritional habits can carry forward into the postpartum period. As many health resources, like PA facilities and postpartum support groups, were inaccessible due to the Coronavirus-19 (COVID-19) pandemic restrictions, it may be plausible that individuals who participated in a prenatal lifestyle intervention continued engaging in positive health behaviours on their own. This study explored experiences of postpartum individuals during the pandemic who had engaged in a prenatal PA and nutrition program prior to COVID-19. Semi-structured interviews were completed with postpartum individuals following a qualitative description approach. The study objectives were to identify and summarize the impact of the COVID-19 pandemic on PA and nutritional behaviours postpartum, and the role of previous participation in a prenatal lifestyle intervention, pre-pandemic, on PA and nutritional habits during postpartum quarantine restrictions. Thirteen participants completed interviews and reported that overall, PA levels stayed the same however, there was a change in PA type, as walking became the prominent choice of PA. Diet became more limited and involved a great deal of meal planning. Participation in a prenatal lifestyle intervention prior to the pandemic positively impacted PA and nutritional habits postpartum during COVID-19 restrictions. Specifically, it enabled individuals to implement walking as a daily PA habit and encouraged important concepts such as mindful eating and meal planning. Prenatal lifestyle interventions can be beneficial in establishing healthy postpartum habits, even during pandemic restrictions
Robustness and epistasis in mutation-selection models
We investigate the fitness advantage associated with the robustness of a
phenotype against deleterious mutations using deterministic mutation-selection
models of quasispecies type equipped with a mesa shaped fitness landscape. We
obtain analytic results for the robustness effect which become exact in the
limit of infinite sequence length. Thereby, we are able to clarify a seeming
contradiction between recent rigorous work and an earlier heuristic treatment
based on a mapping to a Schr\"odinger equation. We exploit the quantum
mechanical analogy to calculate a correction term for finite sequence lengths
and verify our analytic results by numerical studies. In addition, we
investigate the occurrence of an error threshold for a general class of
epistatic landscape and show that diminishing epistasis is a necessary but not
sufficient condition for error threshold behavior.Comment: 20 pages, 14 figure
In the light of directed evolution: Pathways of adaptive protein evolution
Directed evolution is a widely-used engineering strategy for improving the stabilities or biochemical functions of proteins by repeated rounds of mutation and selection. These experiments offer empirical lessons about how proteins evolve in the face of clearly-defined laboratory selection pressures. Directed evolution has revealed that single amino acid mutations can enhance properties such as catalytic activity or stability and that adaptation can often occur through pathways consisting of sequential beneficial mutations. When there are no single mutations that improve a particular protein property experiments always find a wealth of mutations that are neutral with respect to the laboratory-defined measure of fitness. These neutral mutations can open new adaptive pathways by at least 2 different mechanisms. Functionally-neutral mutations can enhance a protein's stability, thereby increasing its tolerance for subsequent functionally beneficial but destabilizing mutations. They can also lead to changes in “promiscuous” functions that are not currently under selective pressure, but can subsequently become the starting points for the adaptive evolution of new functions. These lessons about the coupling between adaptive and neutral protein evolution in the laboratory offer insight into the evolution of proteins in nature
Canalization of the evolutionary trajectory of the human influenza virus
Since its emergence in 1968, influenza A (H3N2) has evolved extensively in
genotype and antigenic phenotype. Antigenic evolution occurs in the context of
a two-dimensional 'antigenic map', while genetic evolution shows a
characteristic ladder-like genealogical tree. Here, we use a large-scale
individual-based model to show that evolution in a Euclidean antigenic space
provides a remarkable correspondence between model behavior and the
epidemiological, antigenic, genealogical and geographic patterns observed in
influenza virus. We find that evolution away from existing human immunity
results in rapid population turnover in the influenza virus and that this
population turnover occurs primarily along a single antigenic axis. Thus,
selective dynamics induce a canalized evolutionary trajectory, in which the
evolutionary fate of the influenza population is surprisingly repeatable and
hence, in theory, predictable.Comment: 29 pages, 5 figures, 10 supporting figure
A New Precision Measurement of the 7Be(p,gamma)8B Cross section with an Implanted 7Be Target
The 7Be(p,gamma)8B reaction plays a central role in the evaluation of solar
neutrino fluxes. We report on a new precision measurement of the cross section
of this reaction, following our previous experiment with an implanted 7Be
target, a raster scanned beam and the elimination of the backscattering loss.
The new measurement incorporates a more abundant 7Be target and a number of
improvements in design and procedure. The point at Elab=991 keV was measured
several times under varying conditions, yielding a value of S17(Ec.m. =850 keV)
= 24.0(5) eV b. Measurements were carried out at lower energies as well. Due to
the precise knowledge of the implanted 7Be density profile it was possible to
reconstitute both the off- and on resonance parts of the cross section and to
obtain from the entire set of measurements an extrapolated value of
S17(0)=21.2(7) eV b.Comment: 4 Pages, 3 Figure
Revising the Language Map of Korea
As linguists develop a deeper understanding of the properties of individual varieties of speech, they often find it necessary to reclassify dialects as independent languages, based on the criterion of intelligibility. This criterion is applied here to Jejueo, the traditional variety of speech used on Jeju Island, a province of the Republic of Korea. Although Jejueo has long been classified as a nonstandard dialect of Korean, evidence from an intelligibility experiment shows that it is not comprehensible to monolingual speakers of Korean and therefore should be treated as a separate language, in accordance with the usual practice within linguistics. This finding calls for a revision to the standard language map of Kore
Maximally-localized generalized Wannier functions for composite energy bands
We discuss a method for determining the optimally-localized set of
generalized Wannier functions associated with a set of Bloch bands in a
crystalline solid. By ``generalized Wannier functions'' we mean a set of
localized orthonormal orbitals spanning the same space as the specified set of
Bloch bands. Although we minimize a functional that represents the total spread
sum_n [ _n - _n^2 ] of the Wannier functions in real space, our method
proceeds directly from the Bloch functions as represented on a mesh of
k-points, and carries out the minimization in a space of unitary matrices
U_mn^k describing the rotation among the Bloch bands at each k-point. The
method is thus suitable for use in connection with conventional
electronic-structure codes. The procedure also returns the total electric
polarization as well as the location of each Wannier center. Sample results for
Si, GaAs, molecular C2H4, and LiCl will be presented.Comment: 22 pages, two-column style with 4 postscript figures embedded. Uses
REVTEX and epsf macros. Also available at
http://www.physics.rutgers.edu/~dhv/preprints/index.html#nm_wan
Sympathetic Background in Tolkien’s Prose
Considering Tolkien’s poetic sensitivity and love of nature, it is no wonder that his fiction abounds with natural images and landscape descriptions. More often than not, these references to the environment seem to be in harmony with the events or the structure of the story. In other words, Tolkien seems to resort to this old universal literary device usually referred to as “sympathetic background” whereby nature mirrors, mimics or reacts to the characters’ deeds, emotions or state of mind. As a contribution to previous and current studies on nature in Middle-earth, this paper examines Tolkien’s art in portraying nature — whether it be the immediate environment (geography, plants, animals …) , or the workings of the elements (the forces constituting the weather) — in an attempt to unveil a subtext under the prism of “sympathetic background”.
Altered thymic differentiation and modulation of arthritis by invariant NKT cells expressing mutant ZAP70
Various subsets of invariant natural killer T (iNKT) cells with different cytokine productions develop in the mouse thymus, but the factors driving their differentiation remain unclear. Here we show that hypomorphic alleles of Zap70 or chemical inhibition of Zap70 catalysis leads to an increase of IFN-gamma-producing iNKT cells (NKT1 cells), suggesting that NKT1 cells may require a lower TCR signal threshold. Zap70 mutant mice develop IL-17-dependent arthritis. In a mouse experimental arthritis model, NKT17 cells are increased as the disease progresses, while NKT1 numbers negatively correlates with disease severity, with this protective effect of NKT1 linked to their IFN-gamma expression. NKT1 cells are also present in the synovial fluid of arthritis patients. Our data therefore suggest that TCR signal strength during thymic differentiation may influence not only IFN-gamma production, but also the protective function of iNKT cells in arthritis
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