463 research outputs found

    Synthesis of Cycloheptatriene-Containing Azetidine Lactones

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    This document is the Accepted Manuscript version of a Published Work that appeared in final form in The Journal of Organic Chemistry, copyright © 2022 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.joc.2c00367.We prepared a collection of complex cycloheptatriene-containing azetidine lactones by applying two key photochemical reactions: “aza-Yang” cyclization and Buchner carbene insertion into aromatic rings. While photolysis of phenacyl amines leads to a rapid charge transfer and elimination, we found that a simple protonation of the amine enables the formation of azetidinols as single diastereomers. We provide evidence, through ultrafast spectroscopy, for the electron transfer from free amines in the excited state. Further, we characterize the aza-Yang reaction by establishing the dependence of the initial reaction rates on the rates of photon absorption. An unanticipated change in reactivity in morpholine analogues is explained through interactions with the tosylate anion. The Buchner reaction proceeds with a slight preference for one diastereomer over the other, and successful reaction requires electron-donating carbene-stabilizing substituents. Overall, 16 compounds were prepared over seven steps. Guided by an increase in structural complexity, efforts such as this one extend the reach of chemists into unexplored chemical space and provide useful quantities of new compounds for studies focused on their properties

    Dark Matter Sub-Halo Counts via Star Stream Crossings

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    Dark matter sub-halos create gaps in the stellar streams orbiting in the halos of galaxies. We evaluate the sub-halo stream crossing integral with the guidance of simulations to find that the linear rate of gap creation, R_gap, in a typical Cold Dark Matter (CDM) galactic halo at 100 kpc is R_gap = 0.0066 M_8^-0.35 kpc^-1 Gyr^-1$, where M_8 = M/10^8 M_sun, is the minimum mass halo that creates a visible gap. The relation can be recast entirely in terms of observables, as R_gap= 0.059 w^-0.85 kpc^-1 Gyr^-1, for w in kpc, normalized at 100 kpc. Using published data, the density of gaps is estimated for M31's NW stream and the Milky Way Pal 5 stream, Orphan stream, and Eastern Banded Structure. The estimated rates of gap creation all have errors of 50% or more due to uncertain dynamical ages and the relatively noisy stream density measurements. The gap rate-width data are in good agreement with the CDM predicted relation. The high density of gaps in the narrow streams require a total halo population of 10^5 sub-halos above a minimum mass of 10^5 M_sun.Comment: ApJ accepted and copy-edite

    Club Sport Legal Liability Practices at NIRSA Institutions

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    Current legal practices in collegiate club sport programs were studied. A 23-item questionnaire consisting primarily of close-ended questions was mailed to 563 campus recreation directors representing all six National Intramural-Recreational Sports Association (NIRSA) regions. Data obtained showed that mean club sport budgets ranged from 51,657inRegion4to51,657 in Region 4 to 135,657 in Region 6, with an overall mean of $69,138 across all regions. Signing a waiver before participating was required by 91 % of the directors. Lack of consistency in waiver language and font size was reported. Only 9% of campus recreation directors always require that an institutional employee travel with a club sport team. The most frequent modes of approved travel for club sport participants were students driving personal cars (94%), renting vans from outside vendors (95%), and the use of private transportation such as a chartered bus (70%). Paid coaches were used by 15% of the directors

    Selected Risk Management Policies, Practices, and Procedures for Intramural Activities at NIRSA Institutions

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    A survey of all National Intramural-Recreational Sports Association (NIRSA) campus recreation directors was conducted to determine the risk management policies, practices, and procedures relating to intramural activities and recreational sports at colleges and universities throughout North America. The survey instrument, in its final form, addressed practices, policies, and procedures of campus recreation directors through 44 questions relating to the following areas: (a) documentation, (b) medical factors, (c) rules and regulations, (d) physical supervision, (e) sportsmanship rating systems, (f) restrictive policies, (g) safety devices, (h) officials-tests-qualifications, and (i) background experiences and training of the respondents. Selected data are presented in terms of (a) the size of institutions (small, medium, and large), (b) location of the institution (rural, urban, and suburban), and (c) whether public or privately supported

    Factors Affecting Risk Management of Indoor Campus Recreation Facilities

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    Factors affecting risk management of indoor campus recreation facilities were studied. Campus recreation directors of 4-year colleges/universities in North America who held memberships in the National Intramural-Recreational Sports Association (NIRSA) responded to a paper survey consisting of 32 dichotomous yes/no and closeended multiple-choice questions. Questions addressed staff certification requirements, use of waivers, number of automatic external defibrillators (AEDs) in the facility, communication and security devices, health screening of participants, and in-person supervision of the facility. Results showed that facilities are open to participants extensively throughout the 7-day week, thus requiring directors to ensure their risk management procedures are up to date—most notably staff members’ CPR and first aid certification, as well as AED training

    Experiences of disabled women during pregnancy, childbirth and early parenting services: implications for occupational therapy

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    The aim of this study was to understand the experiences of women with physical and sensory disability during their interaction with maternity services. The study was funded by a national charity whose previous research identified that disabled women had more negative experiences than non-disabled women (Birthrights, 2013). This paper specifically discusses implications for occupational therapy. Two-phase, inter-professional mixed methods research was used involving online surveys in phase 1 and narrative interviews in phase 2. Recruitment was through disability and parenting networks and social media. Survey data were analysed descriptively and open questions were themed. Phase 2 telephone interviews were audio recorded, transcribed verbatim and analysed thematically. Although overall satisfaction with care was scored highly in phase 1, negative experiences were described. Key challenges included a lack of continuity of carer; women feeling that they were not being listened to; feeling they were treated less favourably because of disability; and 56% feeling that maternity care providers did not have appropriate attitudes to disability. Interview themes echoed these, when women described implications of not being listened to, including that their judgement about their own bodies was ignored or undermined. The research revealed that occupational therapists did little to support women during this time. While some occupational therapy input was described, this focused on equipment provision. Minimal support with the occupations of parenting was described. The results suggest a clear need for interprofessional working and the need for occupational therapists to liaise between midwifery staff and disabled women

    The Vaginal and Urinary Microbiomes in Premenopausal Women With Interstitial Cystitis/Bladder Pain Syndrome as Compared to Unaffected Controls: A Pilot Cross-Sectional Study

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    Interstitial cystitis/bladder pain syndrome (ICBPS) may be related to an altered genitourinary microbiome. Our aim was to compare the vaginal and urinary microbiomes between premenopausal women with ICBPS and unaffected controls. This cross-sectional study screened premenopausal women with an O'Leary-Sant questionnaire (ICBPS if score ≥6 on either index; controls <6 on both). Women completed questionnaires on health characteristics, pelvic floor symptoms (OABq, PFDI-20), body image (mBIS), and sexual function (PISQ-IR). Bacterial genomic DNA was isolated from vaginal and clean-catch urinary specimens; the bacterial 16 rRNA gene was sequenced and analyzed using the QIIME pipeline. We performed UniFrac analysis (β-diversity) and generated Chao1 estimator (richness) and Simpson index (richness and evenness) values. We analyzed 23 ICBPS and 18 non-ICBPS patients. ICBPS patients had increased vaginal deliveries, BMI, and public insurance as well as worsened OAB-q, PFDI-20, mBIS, and PISQ-IR domain scores. Lactobacilli was the most abundant genus in both cohorts, and anaerobic or fastidious predominance was similar between groups (p = 0.99). For both the urine and vagina specimens, Chao1 and Simpson indices were similar between ICBPS and unaffected women. Weighted and unweighted UniFrac analyses showed no differences between groups. A significant correlation existed between the urinary and vaginal Simpson indices in ICBPS women, but not in unaffected women. Premenopausal women with ICBPS, despite worsened socioeconomic indicators and pelvic floor function, were not found to have significantly different urinary and vaginal microbiomes compared to women without ICBPS

    A New Approach to Searching for Dark Matter Signals in Fermi-LAT Gamma Rays

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    Several cosmic ray experiments have measured excesses in electrons and positrons, relative to standard backgrounds, for energies from ~ 10 GeV - 1 TeV. These excesses could be due to new astrophysical sources, but an explanation in which the electrons and positrons are dark matter annihilation or decay products is also consistent. Fortunately, the Fermi-LAT diffuse gamma ray measurements can further test these models, since the electrons and positrons produce gamma rays in their interactions in the interstellar medium. Although the dark matter gamma ray signal consistent with the local electron and positron measurements should be quite large, as we review, there are substantial uncertainties in the modeling of diffuse backgrounds and, additionally, experimental uncertainties that make it difficult to claim a dark matter discovery. In this paper, we introduce an alternative method for understanding the diffuse gamma ray spectrum in which we take the intensity ratio in each energy bin of two different regions of the sky, thereby canceling common systematic uncertainties. For many spectra, this ratio fits well to a power law with a single break in energy. The two measured exponent indices are a robust discriminant between candidate models, and we demonstrate that dark matter annihilation scenarios can predict index values that require "extreme" parameters for background-only explanations.Comment: v1: 11 pages, 7 figures, 1 table, revtex4; v2: 13 pages, 8 figures, 1 table, revtex4, Figure 4 added, minor additions made to text, references added, conclusions unchanged, published versio

    Dark Matter Annihilation around Intermediate Mass Black Holes: an update

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    The formation and evolution of Black Holes inevitably affects the distribution of dark and baryonic matter in the neighborhood of the Black Hole. These effects may be particularly relevant around Supermassive and Intermediate Mass Black Holes (IMBHs), the formation of which can lead to large Dark Matter overdensities, called {\em spikes} and {\em mini-spikes} respectively. Despite being larger and more dense, spikes evolve at the very centers of galactic halos, in regions where numerous dynamical effects tend to destroy them. Mini-spikes may be more likely to survive, and they have been proposed as worthwhile targets for indirect Dark Matter searches. We review here the formation scenarios and the prospects for detection of mini-spikes, and we present new estimates for the abundances of mini-spikes to illustrate the sensitivity of such predictions to cosmological parameters and uncertainties regarding the astrophysics of Black Hole formation at high redshift. We also connect the IMBHs scenario to the recent measurements of cosmic-ray electron and positron spectra by the PAMELA, ATIC, H.E.S.S., and Fermi collaborations.Comment: 12 pages, 7 figures. Invited contribution to NJP Focus Issue on "Dark Matter and Particle Physics

    Annihilation vs. Decay: Constraining dark matter properties from a gamma-ray detection

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    Most proposed dark matter candidates are stable and are produced thermally in the early Universe. However, there is also the possibility of unstable (but long-lived) dark matter, produced thermally or otherwise. We propose a strategy to distinguish between dark matter annihilation and/or decay in the case that a clear signal is detected in gamma-ray observations of Milky Way dwarf spheroidal galaxies with gamma-ray experiments. The sole measurement of the energy spectrum of an indirect signal would render the discrimination between these cases impossible. We show that by examining the dependence of the intensity and energy spectrum on the angular distribution of the emission, the origin could be identified as decay, annihilation, or both. In addition, once the type of signal is established, we show how these measurements could help to extract information about the dark matter properties, including mass, annihilation cross section, lifetime, dominant annihilation and decay channels, and the presence of substructure. Although an application of the approach presented here would likely be feasible with current experiments only for very optimistic dark matter scenarios, the improved sensitivity of upcoming experiments could enable this technique to be used to study a wider range of dark matter models.Comment: 29 pp, 8 figs; replaced to match published version (minor changes and some new references
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