OT on College Campuses: Emerging Models Faciltitating Student Success Through Occupation

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A Spectroscopic Survey of a Sample of Active M Dwarfs

A moderate resolution spectroscopic survey of Fleming's sample of 54 X-ray selected M dwarfs with photometric distances less than 25 pc is presented. Radial and rotation velocities have been measured by fits to the H-alpha profiles. Radial velocities have been measured by cross correlation. Artificial broadening of an observed spectrum has produced a relationship between H-alpha FWHM and rotation speed, which we use to infer rotation speeds for the entire sample by measurement of the H-alpha emission line. We find 3 ultra-fast rotators (UFRs, vsini > 100km/s), and 8 stars with 30 < vsini < 100 km/s. The UFRs have variable emission. Cross-correlation velocities measured for ultra-fast rotators (UFRs) are shown to depend on rotation speed and the filtering used. The radial velocity dispersion of the sample is 17 km/s. A new double emission line spectroscopic binary with a period of 3.55 days has been discovered, and another known one is in the sample. Three other objects are suspected spectroscopic binaries, and at least six are visual doubles. The only star in the sample observed to have significant lithium is a known TW Hya Association member, TWA 8A. These results show that there are a number of young (< 10^8 yr) and very young (< 10^7 yr) low mass stars in the immediate solar neighbourhood. The H-alpha activity strength does not depend on rotation speed. Our fast rotators are less luminous than similarly fast rotators in the Pleiades. They are either younger than the Pleiades, or gained angular momentum in a different way.Comment: 38 pages incl. 14 figures and 4 tables, plus 12 pages of table for electronic journal only; LaTeX, aastex.cls. Accepted 07/18/02 for publication in The Astronomical Journa

Mechanisms of goethite dissolution in the presence of desferrioxamine B and Suwannee River fulvic acid at pH 6.5

Siderophores are Fe3+ specific low MW chelating ligands secreted by microorganisms in response to Fe stress. Low MW organic acids such as oxalate have been shown to enhance siderophore mediated dissolution of Fe3+ oxides. However, the effect of fulvic acid presence on siderophore function remains unknown. We used batch dissolution experiments to investigate Fe release from goethite in the goethite-fulvic acid desferrioxamine B (goethite-SRFA-DFOB) ternary system. Experiments were conducted at pH 6.5 while varying reagent addition sequence. FTIR and UV-Vis spectroscopy were employed to characterise the Fe-DFOB, Fe-SRFA and DFOB–SRFA complexes. Iron released from goethite in the presence of SRFA alone was below detection limit. In the presence of both SRFA and DFOB, dissolved Fe increased with reaction time, presence of the DFOB-SRFA complex, and where SRFA was introduced prior to DFOB. FTIR data show that in the ternary system, Fe3+ is complexed primarily to oxygen of the DFOB hydroxamate group, whilst the carboxylate C=O of SRFA forms an electrostatic association with the terminal NH3+ of DFOB. We propose that SRFA sorbed to goethite lowers the net positive charge of the oxide surface, thus facilitating adsorption of cationic DFOB and subsequent Fe3+ chelation and release. Furthermore, the sorbed SRFA weakens Fe-O bonds at the goethite surface, increasing the population of kinetically labile Fe. This work demonstrates the positive, though indirect role of SRFA in increasing the bioavailability of Fe3+

Investigation of potential gender bias in the peer review system at Reproduction

This study examined whether publication outcome was affected by the gender of author, handling associate editor (AE), or reviewer, and whether there was gender bias in reviewer selection, in the journal Reproduction. Analyses were carried out on 4289 original research manuscripts submitted to the journal between 2007 and 2019. Both female and male AEs appointed more male reviewers than female reviewers, but female AEs were significantly more likely to appoint female reviewers than male AEs were (p < 0.001). When examining the gender of either first or last author manuscripts, those with female authors that were reviewed by female reviewers received better scores than those with male authors that were reviewed by female reviewers (p < 0.05): where the reviewer was male, no such effect was observed. Acceptance rates of manuscripts were similar for both female and male authors, whether first or last, regardless of AE gender. Overall, there was no significant correlation between gender of first or last author, or of AE, on the likelihood of acceptance of a research paper. These data suggest no bias against female authors during the peer review process in this reproductive biology journal

Physicochemical behaviour of a dinuclear uranyl complex formed with an octaphosphinoylated para-tert-butylcalix[8]arene. Spectroscopic studies in solution and in the solid state

Spectrophotometric titrations of an octaphosphinoylated para-tert-butylcalix[8]arene (B8bL8) by uranyl nitrate and vice versa in anhydrous ethanol indicate that the species with 2:1 (uranyl:calixarene) stoichiometry is the major complex in solution. Based on these results, a synthesis route was designed to isolate this complex. The latter is an orange, non-hygroscopic polycrystalline powder, with chemical formula [(UO2)2(NO3)4(B8bL8) 2H2O]2(H2O). (Compd. 1), as ascertained by elemental analysis. Spectroscopic characterization of Compd. 1 in the solid and liquid states suggests that a neutral dinuclear uranyl calixarene complex was formed. MIR and FIR spectra indicate that, four phosphinoyl arms of the calixarene and two monodentate nitrates are bound to each 6-coordinate uranyl ion in the complex because no vibrational frequencies from un-coordinated O@P groups or from ionic nitrates are present; in addition the spectra reveal that water molecules form intramolecular hydrogen bonding with monodentate nitrates. The de-convoluted luminescence and XPS spectra obtained in the solid state point to a similar chemical environment around each uranyl ion, as confirmed by the mono-exponential decay of the luminescence. The more rigid conformation acquired by the calixarene in the complex and the non-symmetrical arrangement of the coordinated nitrates result in a particular feature of the emission spectra at 77 K. No evidence of cation-cation interaction was found. A rough approach to the molecular structure of the complex by molecular modelling based on the experimental findings yielded a molecule that was useful for understanding the physicochemical behaviour of Compd. 1.This work was supported by CONACYT [grant Nr. 36689-E], Mexico; and the Swiss National Science Foundation [grant SCOPES 2000–2002: No. 7BUPJ062293.00/1], Switzerland

The Huqoq Excavation Project : 2014-2017 interim report

Excavations at Huqoq in Israel’s eastern Lower Galilee are bringing to light a Late Roman synagogue, a medieval public building, and the remains of ancient and modern (pre-1948) villages. In this interim report, we describe the major discoveries of the 2014–2017 seasons, including the extraordinary figural mosaics decorating the synagogue floor. Our discoveries provide evidence of a Galilean Jewish community that flourished through the 5th and 6th centuries c.e.—a picture contrasting with recent claims of a decline in Jewish settlement under Byzantine Christian rule. The possibility that the medieval public building might also be a synagogue has important implications for understanding Galilean Jewish settlement in the Middle Ages, about which almost nothing is known. The excavations also shed light on the last phase of the settlement’s long history: the development of the modern village of Yakuk in the 19th through 20th centuries.peer-reviewe

The Critical Role of Notch Ligand Delta-like 1 in the Pathogenesis of Influenza A Virus (H1N1) Infection

Influenza A viral infections have been identified as the etiologic agents for historic pandemics, and contribute to the annual mortality associated with acute viral pneumonia. While both innate and acquired immunity are important in combating influenza virus infection, the mechanism connecting these arms of the immune system remains unknown. Recent data have indicated that the Notch system is an important bridge between antigen-presenting cells (APCs) and T cell communication circuits and plays a central role in driving the immune system to overcome disease. In the present study, we examine the role of Notch signaling during influenza H1N1 virus infection, focusing on APCs. We demonstrate here that macrophages, but not dendritic cells (DCs), increased Notch ligand Delta-like 1 (Dll1) expression following influenza virus challenge. Dll1 expression on macrophages was dependent on retinoic acid-inducible gene-I (RIG-I) induced type-I IFN pathway, and not on the TLR3-TRIF pathway. We also found that IFNα-Receptor knockout mice failed to induce Dll1 expression on lung macrophages and had enhanced mortality during influenza virus infection. Our results further showed that specific neutralization of Dll1 during influenza virus challenge induced higher mortality, impaired viral clearance, and decreased levels of IFN-γ. In addition, we blocked Notch signaling by using γ-secretase inhibitor (GSI), a Notch signaling inhibitor. Intranasal administration of GSI during influenza infection also led to higher mortality, and higher virus load with excessive inflammation and an impaired production of IFN-γ in lungs. Moreover, Dll1 expression on macrophages specifically regulates IFN-γ levels from CD4+and CD8+T cells, which are important for anti-viral immunity. Together, the results of this study show that Dll1 positively influences the development of anti-viral immunity, and may provide mechanistic approaches for modifying and controlling the immune response against influenza H1N1 virus infection

Ramipril mitigates radiation-induced impairment of neurogenesis in the rat dentate gyrus

<p>Abstract</p> <p>Background</p> <p>Sublethal doses of whole brain irradiation (WBI) are commonly administered therapeutically and frequently result in late delayed radiation injuries, manifesting as severe and irreversible cognitive impairment. Neural progenitors within the subgranular zone (SGZ) of the dentate gyrus are among the most radiosensitive cell types in the adult brain and are known to participate in hippocampal plasticity and normal cognitive function. These progenitors and the specialized SZG microenvironment required for neuronal differentiation are the source of neurogenic potential in the adult dentate gyrus, and provide a continuous supply of immature neurons which may then migrate into the adjacent granule cell layer to become mature granule cell neurons. The extreme radiosensitivity of these progenitors and the SGZ microenvironment suggests the hippocampus as a prime target for radiation-induced cognitive impairment. The brain renin-angiotensin system (RAS) has previously been implicated as a potent modulator of neurogenesis within the SGZ and selective RAS inhibitors have been implicated as mitigators of radiation brain injury. Here we investigate the angiotensin converting enzyme (ACE) inhibitor, ramipril, as a mitigator of radiation injury in this context.</p> <p>Methods</p> <p>Adult male Fisher 344 rats received WBI at doses of 10 Gy and 15 Gy. Ramipril was administered beginning 24 hours post-WBI and maintained continuously for 12 weeks.</p> <p>Results</p> <p>Ramipril produced small but significant reductions in the deleterious effects of radiation on progenitor proliferation and neuronal differentiation in the rat dentate gyrus following 10 Gy-WBI, but was not effective following 15 Gy-WBI. Ramipril also reduced the basal rate of neurogenesis within the SGZ in unirradiated control rats.</p> <p>Conclusions</p> <p>Our results indicate that chronic ACE inhibition with ramipril, initiated 24 hours post-irradiation, may reduce apoptosis among SGZ progenitors and/or inflammatory disruption of neurogenic signaling within SGZ microenvironment, and suggest that angiotensin II may participate in maintaining the basal rate of granule cell neurogenesis.</p

Як уникнути підйому рівня води?

East Africa’s Lake Victoria provides resources and services to millions of people on the lake’s shores and abroad. In particular, the lake’s fisheries are an important source of protein, employment, and international economic connections for the whole region. Nonetheless, stock dynamics are poorly understood and currently unpredictable. Furthermore, fishery dynamics are intricately connected to other supporting services of the lake as well as to lakeshore societies and economies. Much research has been carried out piecemeal on different aspects of Lake Victoria’s system; e.g., societies, biodiversity, fisheries, and eutrophication. However, to disentangle drivers and dynamics of change in this complex system, we need to put these pieces together and analyze the system as a whole. We did so by first building a qualitative model of the lake’s social-ecological system. We then investigated the model system through a qualitative loop analysis, and finally examined effects of changes on the system state and structure. The model and its contextual analysis allowed us to investigate system-wide chain reactions resulting from disturbances. Importantly, we built a tool that can be used to analyze the cascading effects of management options and establish the requirements for their success. We found that high connectedness of the system at the exploitation level, through fisheries having multiple target stocks, can increase the stocks’ vulnerability to exploitation but reduce society’s vulnerability to variability in individual stocks. We describe how there are multiple pathways to any change in the system, which makes it difficult to identify the root cause of changes but also broadens the management toolkit. Also, we illustrate how nutrient enrichment is not a self-regulating process, and that explicit management is necessary to halt or reverse eutrophication. This model is simple and usable to assess system-wide effects of management policies, and can serve as a paving stone for future quantitative analyses of system dynamics at local scales