2,127 research outputs found
Impaired pre-competition wellbeing measures can negatively impact running performance in developmental youth female soccer players
This study aimed to determine the association between pre-competition perceived player wellbeing measures and subsequent relative and peak running performance of developmental youth female soccer players (n = 15, age: 16 ± 1 years). Total distance (TD), high-speed (> 3.5 m/s) (HSRD) and very high-speed (> 5.3 m/s) running (VHSRD) were expressed using 1-, 2- and 5-minute epochs and relative (per minute) calculations. Fatigue, sleep quality, upper and lower-body muscle soreness, stress, and mood wellbeing measures were collected via a self-reported questionnaire (1-5 Likert scale). Menstrual cycle phase was collected via a calendar-based countback method. Results demonstrated that reductions in stress was associated with decreased relative and peak TD in all epochs ( p = 0.008-0.040), relative and peak HSRD ( p = 0.006-0.039) in 2- and 5-minute epochs as well as VHSRD in 2-minute epochs ( p = 0.026). For example, a one-point reduction of 'normal' to 'relaxed' is associated with a decrease of 7 m/min in peak TD for 1-minute epochs. One-point increase in fatigue (e.g., 'normal' to 'more tired than normal') displayed a decrease of 7 m/min peak TD for 2-minute ( p = 0.048) and 9 m/min for 5-minute ( p = 0.007) rolling epochs. Likewise, one-point increase in lower-body muscle-soreness (e.g., 'normal' to 'increase in soreness/tightness') was associated with a reduction of 6 m/min peak VHSRD for 1-minute epochs ( p = 0.034). Results suggest that perceived player wellbeing can influence running performance. However, the magnitude of the change in player wellbeing should be considered in a practical sense. </p
Biochemical Systematics of Notothenioid Fishes from Antarctica
Genetic variation at 30 protein-coding loci was examined in seven forms of notothenioid fishes from Antarctica. Multilocus heterozygosity varied from 0.018 to 0.078 across taxa. An analysis of the allozyme data revealed the probable existence of an unrecognized cryptic species within Trematomu5 bemacchii. Pagothenia borchgrevinki is as closely related to some species of Trematomus as are some species of Trematomus to each other. Speciation among the species of Trematomus and Pagothenia appears to have taken place primarily after the separation of Antarctica from Australia
Shadow of a Colossus: A z=2.45 Galaxy Protocluster Detected in 3D Ly-a Forest Tomographic Mapping of the COSMOS Field
Using moderate-resolution optical spectra from 58 background Lyman-break
galaxies and quasars at within a area of the
COSMOS field ( projected area density or mean transverse separation), we reconstruct a 3D
tomographic map of the foreground Ly forest absorption at
with an effective smoothing scale of
comoving. Comparing with 61
coeval galaxies with spectroscopic redshifts in the same volume, we find that
the galaxy positions are clearly biased towards regions with enhanced IGM
absorption in the tomographic map. We find an extended IGM overdensity with
deep absorption troughs at associated with a recently-discovered
galaxy protocluster at the same redshift. Based on simulations matched to our
data, we estimate the enclosed dark matter mass within this IGM overdensity to
be , and
argue based on this mass and absorption strength that it will form at least one
galaxy cluster with , although its elongated nature suggests that
it will likely collapse into two separate clusters. We also point out a compact
overdensity of six MOSDEF galaxies at within a radius and , which does not appear
to have a large associated IGM overdensity. These results demonstrate the
potential of Ly forest tomography on larger volumes to study galaxy
properties as a function of environment, as well as revealing the large-scale
IGM overdensities associated with protoclusters and other features of
large-scale structure.Comment: To be submitted to ApJ. Figure 3 can be viewed on Youtube:
https://youtu.be/KeW1UJOPMY
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Selective nitrogen adsorption via backbonding in a metal-organic framework with exposed vanadium sites.
Industrial processes prominently feature Ï-acidic gases, and an adsorbent capable of selectively interacting with these molecules could enable important chemical separations1-4. Biological systems use accessible, reducing metal centres to bind and activate weakly Ï-acidic species, such as N2, through backbonding interactions5-7, and incorporating analogous moieties into a porous material should give rise to a similar adsorption mechanism for these gaseous substrates8. Here, we report a metal-organic framework featuring exposed vanadium(II) centres capable of back-donating electron density to weak Ï acids to successfully target Ï acidity for separation applications. This adsorption mechanism, together with a high concentration of available adsorption sites, results in record N2 capacities and selectivities for the removal of N2 from mixtures with CH4, while further enabling olefin/paraffin separations at elevated temperatures. Ultimately, incorporating such Ï-basic metal centres into porous materials offers a handle for capturing and activating key molecular species within next-generation adsorbents
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X-ray Spectroscopic Study of the Electronic Structure of a Trigonal High-Spin Fe(IV)âO Complex Modeling Non-Heme Enzyme Intermediates and Their Reactivity
Fe K-edge X-ray absorption spectroscopy (XAS) has long been used for the study of high-valent iron intermediates in biological and artificial catalysts. 4p-mixing into the 3d orbitals complicates the pre-edge analysis but when correctly understood via 1s2p resonant inelastic X-ray scattering and Fe L-edge XAS, it enables deeper insight into the geometric structure and correlates with the electronic structure and reactivity. This study shows that in addition to the 4p-mixing into the 3dz2 orbital due to the short iron-oxo bond, the loss of inversion in the equatorial plane leads to 4p mixing into the 3dx2-y2,xy, providing structural insight and allowing the distinction of 6- vs 5-coordinate active sites as shown through application to the Fe(IV)âO intermediate of taurine dioxygenase. Combined with O K-edge XAS, this study gives an unprecedented experimental insight into the electronic structure of Fe(IV)âO active sites and their selectivity for reactivity enabled by the Ï-pathway involving the 3dxz/yz orbitals. Finally, the large effect of spin polarization is experimentally assigned in the pre-edge (i.e., the α/ÎČ splitting) and found to be better modeled by multiplet simulations rather than by commonly used time-dependent density functional theory
Effect of d-cycloserine on fear extinction training in adults with social anxiety disorder
© 2019 Hofmann et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Preclinical and clinical data have shown that D-cycloserine (DCS), a partial agonist at the N-methyl-d-aspartate receptor complex, augments the retention of fear extinction in animals and the therapeutic learning from exposure therapy in humans. However, studies with nonclinical human samples in de novo fear conditioning paradigms have demonstrated minimal to no benefit of DCS. The aim of this study was to evaluate the effects of DCS on the retention of extinction learning following de novo fear conditioning in a clinical sample. Eighty-one patients with social anxiety disorder were recruited and underwent a previously validated de novo fear conditioning and extinction paradigm over the course of three days. Of those, only 43 (53%) provided analyzable data. During conditioning on Day 1, participants viewed images of differently colored lamps, two of which were followed by with electric shock (CS+) and a third which was not (CS-). On Day 2, participants were randomly assigned to receive either 50 mg DCS or placebo, administered in a double-blind manner 1 hour prior to extinction training with a single CS+ in a distinct context. Day 3 consisted of tests of extinction recall and renewal. The primary outcome was skin conductance response to conditioned stimuli, and shock expectancy ratings were examined as a secondary outcome. Results showed greater skin conductance and expectancy ratings in response to the CS+ compared to CS- at the end of conditioning. As expected, this difference was no longer present at the end of extinction training, but returned at early recall and renewal phases on Day 3, showing evidence of return of fear. In contrast to hypotheses, DCS had no moderating influence on skin conductance response or expectancy of shock during recall or renewal phases. We did not find evidence of an effect of DCS on the retention of extinction learning in humans in this fear conditioning and extinction paradigm
Imaging ultrafast excited state pathways in transition metal complexes by X-ray transient absorption and scattering using X-ray free electron laser source
This report will describe our recent studies of transition metal complex structural dynamics on the fs and ps time scales using an X-ray free electron laser source, Linac Coherent Light Source (LCLS). Ultrafast XANES spectra at the Ni K-edge of nickel(II) tetramesitylporphyrin (NiTMP) were successfully measured for optically excited state at a timescale from 100 fs to 50 ps, providing insight into its sub-ps electronic and structural relaxation processes. Importantly, a transient reduced state Ni(I) (Ï, 3d(x2ây2)) electronic state is captured through the interpretation of a short-lived excited state absorption on the low-energy shoulder of the edge, which is aided by the computation of X-ray transitions for postulated excited electronic states. The observed and computed inner shell to valence orbital transition energies demonstrate and quantify the influence of electronic configuration on specific metal orbital energies. A strong influence of the valence orbital occupation on the inner shell orbital energies indicates that one should not use the transition energy from 1s to other orbitals to draw conclusions about the d-orbital energies. For photocatalysis, a transient electronic configuration could influence d-orbital energies up to a few eV and any attempt to steer the reaction pathway should account for this to ensure that external energies can be used optimally in driving desirable processes. NiTMP structural evolution and the influence of the porphyrin macrocycle conformation on relaxation kinetics can be likewise inferred from this study
Metalloprotein entatic control of ligand-metal bonds quantified by ultrafast x-ray spectroscopy
The multifunctional protein cytochrome c (cyt c) plays key roles in electron transport and apoptosis, switching function by modulating bonding between a heme iron and the sulfur in a methionine residue. This Fe-S(Met) bond is too weak to persist in the absence of protein constraints. We ruptured the bond in ferrous cyt c using an optical laser pulse and monitored the bond reformation within the protein active site using ultrafast x-ray pulses from an x-ray free-electron laser, determining that the Fe-S(Met) bond enthalpy is ~4 kcal/mol stronger than in the absence of protein constraints. The 4 kcal/mol is comparable with calculations of stabilization effects in other systems, demonstrating how biological systems use an entatic state for modest yet accessible energetics to modulate chemical function
Chemokine CCL9 Is Upregulated Early in Chronic Kidney Disease and Counteracts Kidney Inflammation and Fibrosis
Inflammation and fibrosis play an important pathophysiological role in chronic kidney
disease (CKD), with pro-inflammatory mediators and leukocytes promoting organ damage with
subsequent fibrosis. Since chemokines are the main regulators of leukocyte chemotaxis and tissue
inflammation, we performed systemic chemokine profiling in early CKD in mice. This revealed
(C-C motif) ligands 6 and 9 (CCL6 and CCL9) as the most upregulated chemokines, with significantly higher levels of both chemokines in blood (CCL6: 3â4 fold; CCL9: 3â5 fold) as well as kidney
as confirmed by Enzyme-linked Immunosorbent Assay (ELISA) in two additional CKD models.
Chemokine treatment in a mouse model of early adenine-induced CKD almost completely abolished
the CKD-induced infiltration of macrophages and myeloid cells in the kidney without impact on circulating leukocyte numbers. The other way around, especially CCL9-blockade aggravated monocyte
and macrophage accumulation in kidney during CKD development, without impact on the ratio
of M1-to-M2 macrophages. In parallel, CCL9-blockade raised serum creatinine and urea levels as
readouts of kidney dysfunction. It also exacerbated CKD-induced expression of collagen (3.2-fold)
and the pro-inflammatory chemokines CCL2 (1.8-fold) and CCL3 (2.1-fold) in kidney. Altogether, this
study reveals for the first time that chemokines CCL6 and CCL9 are upregulated early in experimental
CKD, with CCL9-blockade during CKD initiation enhancing kidney inflammation and fibrosis
STAT1 Pathway Mediates Amplification of Metastatic Potential and Resistance to Therapy
BACKGROUND: Traditionally IFN/STAT1 signaling is connected with an anti-viral response and pro-apoptotic tumor-suppressor functions. Emerging functions of a constitutively activated IFN/STAT1 pathway suggest an association with an aggressive tumor phenotype. We hypothesized that tumor clones that constitutively overexpress this pathway are preferentially selected by the host microenvironment due to a resistance to STAT1-dependent cytotoxicity and demonstrate increased metastatic ability combined with increased resistance to genotoxic stress. METHODOLOGY/PRINCIPAL FINDINGS: Here we report that clones of B16F1 tumors grown in the lungs of syngeneic C57BL/6 mice demonstrate variable transcriptional levels of IFN/STAT1 pathway expression. Tumor cells that constitutively overexpress the IFN/STAT1 pathway (STAT1(H) genotype) are selected by the lung microenvironment. STAT1(H) tumor cells also demonstrate resistance to IFN-gamma (IFNgamma), ionizing radiation (IR), and doxorubicin relative to parental B16F1 and low expressors of the IFN/STAT1 pathway (STAT1(L) genotype). Stable knockdown of STAT1 reversed the aggressive phenotype and decreased both lung colonization and resistance to genotoxic stress. CONCLUSIONS: Our results identify a pathway activated by tumor-stromal interactions thereby selecting for pro-metastatic and therapy-resistant tumor clones. New therapies targeted against the IFN/STAT1 signaling pathway may provide an effective strategy to treat or sensitize aggressive tumor clones to conventional cancer therapies and potentially prevent distant organ colonization
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