275 research outputs found

    A comparison of equitable per diem policies for units deployed to U.S. bases

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    This thesis addresses the per diem funding requirements for units deployed to U.S. bases, Three alternative programs are compared: (1) the current Lodgings Plus policy, (2) AIRPAC's Smart TAD test, and (3) the DoD Task Force to Reengineer Travel recommendation to provide rations in kind. The impacts of these three alternatives on the Type Commanders, travelers, messing facilities, and MWR activities are examined to ensure that the missions can be accomplished while maintaining a high quality of life for the travelers. The primary areas evaluated are galley operations, missed meal reimbursement, and MWR compensation. Findings include that savings can be achieved by adopting the Rations In Kind policy, while still maintaining a high quality of life for the travelers. With the reduction in the DoN budget, some action is required to bridge the predicted shortfall between available fluiding and the budget needed to fully support the travel requirements. This study recommends that AIRPAC's Smart TAD test be modified and expanded to ensure that travel funds are available to support future operational commitments and readiness.http://archive.org/details/acomparisonofequ109457467U.S. Navy (U.S.N.) author

    Unravelling the Role of the Pentafluoroorthotellurate Group as a Ligand in Nickel Chemistry

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    The pentafluoroorthotellurate group (teflate, OTeF5) is able to form species, for which only the fluoride analogues are known. Despite nickel fluorides being widely investigated, nickel teflates have remained elusive for decades. By reaction of [NiCl4]2− and neat ClOTeF5, we have synthesized the homoleptic [Ni(OTeF5)4]2− anion, which presents a distorted tetrahedral structure, unlike the polymeric [NiF4]2−. This high‐spin complex has allowed the study of the electronic properties of the teflate group, which can be classified as a weak/medium‐field ligand, and therefore behaves as the fluoride analogue also in ligand‐field terms. The teflate ligands in [NEt4]2[Ni(OTeF5)4] are easily substituted, as shown by the formation of [Ni(NCMe)6][OTeF5]2 by dissolving it in acetonitrile. Nevertheless, careful reactions with other conventional ligands have enabled the crystallization of nickel teflate complexes with different coordination geometries, i.e. [NEt4]2[trans‐Ni(OEt2)2(OTeF5)4] or [NEt4][Ni(bpyMe2)(OTeF5)3]

    Pharmacological assessment of the contribution of the arterial baroreflex to sympathetic discharge patterns in healthy humans

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    To study how changes in baroreceptor afferent activity affect patterns of sympathetic neural activation, we manipulated arterial blood pressure with intravenous nitroprusside (NTP) and phenylephrine (PE) and measured action potential (AP) patterns with wavelet-based methodology. We hypothesized that 1) baroreflex unloading (NTP) would increase firing of low-threshold axons and recruitment of latent axons and 2) baroreflex loading (PE) would decrease firing of low-threshold axons. Heart rate (HR, ECG), arterial blood pressure (BP, brachial catheter), and muscle sympathetic nerve activity (MSNA, microneurography of peroneal nerve) were measured at baseline and during steady-state systemic, intravenous NTP (0.5-1.2 ”g·kg -1 ·min -1 , n = 13) or PE (0.2-1.0 ”g·kg -1 ·min -1 , n = 9) infusion. BP decreased and HR and integrated MSNA increased with NTP (P \u3c 0.01). AP incidence (326 ± 66 to 579 ± 129 APs/100 heartbeats) and AP content per integrated burst (8 ± 1 to 11 ± 2 APs/burst) increased with NTP (P \u3c 0.05). The firing probability of low-threshold axons increased with NTP, and recruitment of high-threshold axons was observed (22 ± 3 to 24 ± 3 max cluster number, 9 ± 1 to 11 ± 1 clusters/burst; P \u3c 0.05). BP increased and HR and integrated MSNA decreased with PE (P \u3c 0.05). PE decreased AP incidence (406 ± 128 to 166 ± 42 APs/100 heartbeats) and resulted in fewer unique clusters (15 ± 2 to 9 ± 1 max cluster number, P \u3c 0.05); components of an integrated burst (APs or clusters per burst) were not altered (P \u3e 0.05). These data support a hierarchical pattern of sympathetic neural activation during manipulation of baroreceptor afferent activity, with rate coding of active neurons playing the predominant role and recruitment/derecruitment of higher-threshold units occurring with steady-state hypotensive stress. NEW & NOTEWORTHY To study how changes in baroreceptor afferent activity affect patterns of sympathetic neural activation, we manipulated arterial blood pressure with intravenous nitroprusside and phenylephrine and measured sympathetic outflow with wavelet-based methodology. Baroreflex unloading increased sympathetic activity by increasing firing probability of low-threshold axons (rate coding) and recruiting new populations of high-threshold axons. Baroreflex loading decreased sympathetic activity by decreasing the firing probability of larger axons (derecruitment); however, the components of an integrated burst were unaffected

    A dark siren measurement of the Hubble constant using gravitational wave events from the first three LIGO/Virgo observing runs and DELVE

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    The current and next observation seasons will detect hundreds of gravitational waves (GWs) from compact binary systems coalescence at cosmological distances. When combined with independent electromagnetic measurements, the source redshift will be known, and we will be able to obtain precise measurements of the Hubble constant H0 via the distance–redshift relation. However, most observed mergers are not expected to have electromagnetic counterparts, which prevents a direct redshift measurement. In this scenario, one possibility is to use the dark sirens method that statistically marginalizes over all the potential host galaxies within the GW location volume to provide a probabilistic source redshift. Here we presented H0 measurements using two new dark sirens compared to previous analyses using DECam data: GW190924 021846 and GW200202 154313. The photometric redshifts of the possible host galaxies of these two events are acquired from the DECam Local Volume Exploration Survey (DELVE) carried out on the Blanco telescope at Cerro Tololo. The combination of the H0 posterior from GW190924 021846 and GW200202 154313 together with the brightsiren GW170817 leadsto H0 = 68.84+15.51 −7.74 km s−1 Mpc−1. Including these two dark sirens improves the 68 per cent confidence interval (CI) by 7 per cent over GW170817 alone. This demonstrates that the addition of well-localized dark sirens in such analysis improves the precision of cosmological measurements. Using a sample containing 10 well-localized dark sirens observed during the third LIGO/Virgo observation run, without the inclusion of GW170817, we determine a measurement of H0 = 76.00+17.64 −13.45 km s−1 Mpc−1

    First Observation of Self-Amplified Spontaneous Emission in a Free-Electron Laser at 109 nm Wavelength

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    We present the first observation of Self-Amplified Spontaneous Emission (SASE) in a free-electron laser (FEL) in the Vacuum Ultraviolet regime at 109 nm wavelength (11 eV). The observed free-electron laser gain (approx. 3000) and the radiation characteristics, such as dependency on bunch charge, angular distribution, spectral width and intensity fluctuations all corroborate the existing models for SASE FELs.Comment: 6 pages including 6 figures; e-mail: [email protected]

    Spektroskopische Eigenschaften eines biologisch‐relevanten [Fe2(Ό‐O)2] Diamond‐Core‐Motivs mit einem kurzen Eisen‐Eisen‐Abstand

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    Dieisen-Kofaktoren in Enzymen vollziehen diverse anspruchsvolle Transformationen. Die Strukturen hoch-valenter Intermediate (Q in der löslichen Methanmonooxygenase und X in der Ribonukleotidreduktase) sind Gegenstand aktueller Diskussionen, seit Fe-Fe-AbstĂ€nde von 2.1–3.4 Å eine Zuordnung zu geöffneten und geschlossen Kernen mit verbrĂŒckenden oder terminalen Oxido-Gruppen in den aktiven Zentren ermöglichen. In dieser Studie berichten wir die kristallografische und spektroskopische Charakterisierung eines FeIII2(ÎŒ-O)2-Komplexes (2) mit tetraedrischen (4C) Zentren sowie einem geringen Fe-Fe-Abstand (2.52 Å), der in Lösungsmitteln bestĂ€ndig ist. 2 zeigt eine große Fe-K-Vorkanten-IntensitĂ€t. Diese resultiert aus der starken Asymmetrie an den TD-FeIII-Zentren bedingt durch die kurzen Fe-ÎŒ-O-Bindungen. WĂ€hrend ein Fe-Fe-Abstand von ≈2.5 Å fĂŒr sechsfach-koordinierte Zentren in Q und X unwahrscheinlich ist, könnte ein Fe2(ÎŒ-O)2-Kern mit vierfacher (oder möglicherweise auch fĂŒnffacher) Koordination flexibel genug sein, um eine kurze Fe-Fe-Separierung mit großer Vorkanten-IntensitĂ€t zu ermöglichen. Diese Erkenntnis kann dazu beitragen, dass weitere Modelle fĂŒr die Strukturen der hoch-valenten Dieisen-Intermediate, die sich im Zuge der biologischen O2-Aktivierung bilden, in Betracht gezogen werden

    Uranyl oxo activation and functionalization by metal cation coordination

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    International audienceThe oxo groups in the uranyl ion [UO2_2]2+^{2+} , one of many oxo cations formed by metals from across the periodic table—are particularly inert, which explains the dominance of this ion in the laboratory and its persistence as an environmental contaminant. In contrast, transition metal oxo (M=O) compounds can be highly reactive and carry out difficult reactions such as the oxygenation of hydrocarbons. Here we show how the sequential addition of a lithium metal base to the uranyl ion constrained in a ‘Pacman’ environment results in lithium coordination to the U=O bonds and single-electron reduction. This reaction depends on the nature and stoichiometry of the lithium reagent and suggests that competing reduction and C–H bond activation reactions are occurring
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