1,472 research outputs found

    Towards reduction of type II theories on SU(3) structure manifolds

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    We revisit the reduction of type II supergravity on SU(3) structure manifolds, conjectured to lead to gauged N=2 supergravity in 4 dimensions. The reduction proceeds by expanding the invariant 2- and 3-forms of the SU(3) structure as well as the gauge potentials of the type II theory in the same set of forms, the analogues of harmonic forms in the case of Calabi-Yau reductions. By focussing on the metric sector, we arrive at a list of constraints these expansion forms should satisfy to yield a base point independent reduction. Identifying these constraints is a first step towards a first-principles reduction of type II on SU(3) structure manifolds.Comment: 20 pages; v2: condition (2.13old) on expansion forms weakened, replaced by (2.13new), (2.14new

    Characterization of Physical and Cognitive Performance and Hydration in Older Adults

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    In younger adults, dehydration has been shown to impair physical and cognitive performance. Older adults are habitually hypohydrated alongside experiencing physical and cognitive performance deficits. Despite these deficits, the link between these factors remains unexplored. Purpose: To examine the effect of hydration status on physical and cognitive performance in older adults. Methods: Sixteen (5 men and 11 women) community-dwelling adults (74±7yr; 78.2±15.0kg; 161±11cm) completed measurements of hydration status (urine specific gravity [USG], urine color), bioelectrical impedance analysis (lean mass, fat mass, total body fluid, intracellular to extracellular fluid ratio [ICF: ECF]), blood pressure, physical performance (handgrip strength test, sit-to-stand test, and a timed-up-and-go test), and reaction time (Flanker task). Hierarchical cluster analysis was performed on the distance matrix of USG and urine color to group participants. One-way ANOVAs were performed to determine differences among groups. Results: Hierarchical cluster analysis assigned participants to 4 groups (group1, n=3; group2, n=4; group3, n=5; group4,n=4). Consistent with the cluster analysis, each group had significantly (p1: 1.0±0.0, group2: 2.3±0.3, group3: 4.2±0.4, group4, 6.0±0.0). In addition, the reaction time was significantly different among groups. For group1, compatible and incompatible tasks (compatible: 1116±71.7s, p=0.049; incompatible: 1205±13.4ms, p=0.042) had a longer response time compared to group2(compatible: 640±67.5ms; incompatible: 688±74.0ms), group3 (compatible: 725±67.4ms; incompatible: 796±174.2ms), and group4 (compatible: 731±139.8ms; incompatible: 782±122.7ms). No significant differences were observed for lean mass, fat mass, total body fluid, ICF:ECF, blood pressure, handgrip strength, sit-to-stand test, and time-up-and-go test. Conclusion: Despite grouping by USG and urine color, no relationship was observed between body composition and physical performance. Surprisingly, hydrated individuals performed poorly cognitively compared to less hydrated individuals. We suggest these differences may reflect varying individual cognitive functions, not hydration status, among free-living older adults

    Comparative evaluation of a novel, moderately hypofractionated radiation protocol in 56 dogs with symptomatic intracranial neoplasia

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    BACKGROUND: Use of strongly hypofractionated radiation treatments in dogs with intracranial neoplasia did not improve outcomes and yielded increased rates of toxicosis. OBJECTIVES: To evaluate safety and efficacy of a new, moderately hypofractionated radiation protocol of 10 × 4 Gy compared to a standard protocol. ANIMALS: Convenience sample of 56 client-owned dogs with primary symptomatic brain tumors. METHODS: Retrospective observational study. Twenty-six dogs were assigned to the control standard protocol of 20 × 2.5 Gy (group A) and 30 dogs to the new protocol of 10 × 4 Gy (group B), assigned on owners' informed consent. Statistical analysis was conducted under the "as treated" regime, using Kaplan-Meier and Cox-regression analysis. Treatment was delivered with technically advanced image-guided radiation therapy. The 2 treatment groups were compared in terms of outcome and signs of toxicosis. RESULTS: Overall progression-free interval (PFI) and overall survival (OS) time were favorable, with 663 (95%CI: 497;828) and 637 (95%CI: 403;870) days, respectively. We found no significant difference between the two groups: PFI for dogs in group A vs B was 608 (95%CI: 437;779) days and mean (median not reached) 863 (95%CI: 644;1083) days, respectively (P = .89), and OS for dogs in group A vs B 610 (95%CI: 404;816) and mean (median not reached) 796 (95%CI: 586;1007) days (P = .83). CONCLUSION AND CLINICAL IMPORTANCE: In conclusion, 10 × 4 Gy is a safe and efficient protocol for treatment of primary intracranial neoplasia and future dose escalation can be considered

    Reactor physics project progress report

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    Statement of responsibility on title page reads: Editors: M.J. Driscoll and T.J. Thompson; Contributors: F.M. Clikeman, J.N. Donohew, M.J. Driscoll, J.D. Eckard, T.L. Harper, Y. Hukai, I. Kaplan, C.H. Kim, Y.-M. Lefevre, T.C. Leung, N.R. Ortiz, N.C. Rasmussen, C.S. Rim, S.S. Seth, A.T. Supple C. Takahata, and T.J. Thompson"MIT-3944-1."Progress report; September 30, 1968U.S. Atomic Energy Commission contract AT(30-1)-394

    A comparison of vestibular and auditory phenotypes in inbred mouse strains

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    The purposes of this research were to quantify gravity receptor function in inbred mouse strains and compare vestibular and auditory function for strain- and age-matched animals. Vestibular evoked potentials (VsEPs) were collected for 19 inbred strains at ages from 35 to 389 days old. On average, C57BL/6J (35 to 190 days), BALB/cByJ, C3H/HeSnJ, CBA/J, and young LP/J mice had VsEP thresholds comparable to normal. Elevated VsEP thresholds were found for elderly C57BL/ 6J, NOD.NONH2kb, BUB/BnJ, A/J, DBA/2J, NOD/LtJ, A/WySnJ, MRL/MpJ, A/HeJ, CAST/Ei, SJL/J, elderly LP/J, and CE/J. These results suggest that otolithic function varies among inbred strains and several strains displayed gravity receptor deficits by 90 days old. Auditory brainstem response (ABR) thresholds were compared to VsEP thresholds for 14 age-matched strains. C57BL/6J mice (up to 190 days) showed normal VsEPs with normal to mildly elevated ABR thresholds. Four strains (BUB/BnJ, NOD/LtJ, A/J, elderly LP/J) had significant hearing loss and elevated VsEP thresholds. Four strains (DBA/2J, A/WySnJ, NOD. NONH2kb, A/HeJ) had elevated VsEP thresholds (including absent VsEPs) with mild to moderate elevations in ABR thresholds. Three strains (MRL/MpJ, Ce/J, SJL/J) had significant vestibular loss with no concomitant hearing loss. These results suggest that functional change in one sensory system does not obligate change in the other. We hypothesize that genes responsible for early onset hearing loss may affect otolithic function, yet the time course of functional change may vary. In addition, some genetic mutations may produce primarily gravity receptor deficits. Potential genes responsible for selective gravity receptor impairment demonstrated herein remain to be identified. Originally published in Brain Research 1091(1), 2006

    GHOST Commissioning Science Results II: a very metal-poor star witnessing the early Galactic assembly

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    This study focuses on Pristine_180956.78\_180956.78−-294759.8294759.8 (hereafter P180956, [Fe/H] =−1.95±0.02=-1.95\pm0.02), a star selected from the Pristine Inner Galaxy Survey (PIGS), and followed-up with the recently commissioned Gemini High-resolution Optical SpecTrograph (GHOST) at the Gemini South telescope. The GHOST spectrograph's high efficiency in the blue spectral region (3700−48003700-4800~\AA) enables the detection of elemental tracers of early supernovae (e.g. Al, Mn, Sr, Eu), which were not accessible in the previous analysis of P180956. The star exhibits chemical signatures resembling those found in ultra-faint dwarf systems, characterised by very low abundances of neutron-capture elements (Sr, Ba, Eu), which are uncommon among stars of comparable metallicity in the Milky Way. Our analysis suggests that P180956 bears the chemical imprints of a small number (2 or 4) of low-mass hypernovae (\sim10-15\msun), which are needed to reproduce the abundance pattern of the light-elements (e.g. [Si, Ti/Mg, Ca] ∌0.6\sim0.6), and one fast-rotating intermediate-mass supernova (\sim300\kms, \sim80-120\msun). Both types of supernovae explain the high [Sr/Ba] of P180956 (∌1.2\sim1.2). The small pericentric (\sim0.7\kpc) and apocentric (\sim13\kpc) distances and its orbit confined to the plane (\lesssim 2\kpc), indicate that this star was likely accreted during the early Galactic assembly phase. Its chemo-dynamical properties suggest that P180956 formed in a system similar to an ultra-faint dwarf galaxy accreted either alone, as one of the low-mass building blocks of the proto-Galaxy, or as a satellite of Gaia-Sausage-Enceladus. The combination of Gemini's large aperture with GHOST's high efficiency and broad spectral coverage makes this new spectrograph one of the leading instruments for near-field cosmology investigations.Comment: Submitted to MNRAS. 8 figures, 15page

    Measurement of the cosmic ray spectrum above 4×10184{\times}10^{18} eV using inclined events detected with the Pierre Auger Observatory

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    A measurement of the cosmic-ray spectrum for energies exceeding 4×10184{\times}10^{18} eV is presented, which is based on the analysis of showers with zenith angles greater than 60∘60^{\circ} detected with the Pierre Auger Observatory between 1 January 2004 and 31 December 2013. The measured spectrum confirms a flux suppression at the highest energies. Above 5.3×10185.3{\times}10^{18} eV, the "ankle", the flux can be described by a power law E−γE^{-\gamma} with index Îł=2.70±0.02 (stat)±0.1 (sys)\gamma=2.70 \pm 0.02 \,\text{(stat)} \pm 0.1\,\text{(sys)} followed by a smooth suppression region. For the energy (EsE_\text{s}) at which the spectral flux has fallen to one-half of its extrapolated value in the absence of suppression, we find Es=(5.12±0.25 (stat)−1.2+1.0 (sys))×1019E_\text{s}=(5.12\pm0.25\,\text{(stat)}^{+1.0}_{-1.2}\,\text{(sys)}){\times}10^{19} eV.Comment: Replaced with published version. Added journal reference and DO
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