11,410 research outputs found
A New Look at the Schouten-Nijenhuis, Fr\"olicher-Nijenhuis and Nijenhuis-Richardson Brackets for Symplectic Spaces
In this paper we re-express the Schouten-Nijenhuis, the Fr\"olicher-Nijenhuis
and the Nijenhuis-Richardson brackets on a symplectic space using the extended
Poisson brackets structure present in the path-integral formulation of
classical mechanics.Comment: 27+1 pages, Latex, no figure
Saturated Critical Heat Flux in a Multi-Microchannel Heat Sink Fed by a Split Flow System
An extensive experimental campaign has been carried out for the measurement of saturated critical heat flux in a multi-microchannel copper heat sink. The heat sink was formed by 29 parallel channels that were 199 ÎŒm wide and 756 ÎŒm deep. In order to increase the critical heat flux and reduce the two-phase pressure drop, a split flow system was implemented with one central inlet at the middle of the channels and two outlets at either end. The base critical heat flux was measured using three HFC Refrigerants (R134a, R236fa and R245fa) for mass fluxes ranging from 250 to 1500 kg/m2 s, inlet subcoolings from â25 to â5 K and saturation temperatures from 20 to 50 °C. The parametric effects of mass velocity, saturation temperature and inlet subcooling were investigated. The analysis showed that significantly higher CHF was obtainable with the split flow system (one inletâtwo outlets) compared to the single inletâsingle outlet system, providing also a much lower pressure drop. Notably several existing predictive methods matched the experimental data quite well and quantitatively predicted the benefit of higher CHF of the split flow
Entanglement detection in hybrid optomechanical systems
We study a device formed by a Bose Einstein condensate (BEC) coupled to the
field of a cavity with a moving end-mirror and find a working point such that
the mirror-light entanglement is reproduced by the BEC-light quantum
correlations. This provides an experimentally viable tool for inferring
mirror-light entanglement with only a limited set of assumptions. We prove the
existence of tripartite entanglement in the hybrid device, persisting up to
temperatures of a few milli-Kelvin, and discuss a scheme to detect it.Comment: 6 pages, 7 figures, published versio
Dark Energy Dominance and Cosmic Acceleration in First Order Formalism
The current accelerated universe could be produced by modified gravitational
dynamics as it can be seen in particular in its Palatini formulation. We
analyze here a specific non-linear gravity-scalar system in the first order
Palatini formalism which leads to a FRW cosmology different from the purely
metric one. It is shown that the emerging FRW cosmology may lead either to an
effective quintessence phase (cosmic speed-up) or to an effective phantom
phase. Moreover, the already known gravity assisted dark energy dominance
occurs also in the first order formalism. Finally, it is shown that a dynamical
theory able to resolve the cosmological constant problem exists also in this
formalism, in close parallel with the standard metric formulation.Comment: 21 pages, LaTeX file, no figures. Replaced version to be published on
Phys. Rev.
First observation of Cherenkov rings with a large area CsI-TGEM-based RICH prototype
We have built a RICH detector prototype consisting of a liquid C6F14 radiator
and six triple Thick Gaseous Electron Multipliers (TGEMs), each of them having
an active area of 10x10 cm2. One triple TGEM has been placed behind the liquid
radiator in order to detect the beam particles, whereas the other five have
been positioned around the central one at a distance to collect the Cherenkov
photons. The upstream electrode of each of the TGEM stacks has been coated with
a 0.4 micron thick CsI layer.
In this paper, we will present the results from a series of laboratory tests
with this prototype carried out using UV light, 6 keV photons from 55Fe and
electrons from 90Sr as well as recent results of tests with a beam of charged
pions where for the first time Cherenkov Ring images have been successfully
recorded with TGEM photodetectors. The achieved results prove the feasibility
of building a large area Cherenkov detector consisting of a matrix of TGEMs.Comment: Presented at the International Conference NDIP-11, Lyon,July201
Studio RIFRA: il rischio fratturativo in Italia
L'osteoporosi \ue8 un disordine scheletrico cronico-evolutivo, caratferizzato dalla perdita dell'equilibrio
del metabolismo osseo con conseguente degenerazione quantitativa e qualitativa che compromette la
resistenza dell'osso e predispone ad un aumentato rischio di fratture. Colpisce soprattutto il sesso
femminile,conunaprevalenza del33%nelrange tra60eT0aacheaumentaconl'avanzaredell'et\ue0.
Pu\uf2 rimanere clinicamente silente e successivamente manifestarsi con fratture (vertebrali 100.000
casi/anno, di polso 85.000 casi/anno e femorali 80.000 casi/anno). Le fratture da fragilit\ue0 comportano
gravi conse gse\ueeze, sia a livello clinico individuale che sociale ed economico; rappresenrano pertanto
una fonte di disabilit\ue0 complessa, che in quanto tale necessita di una presa in carico globale.
Lo studio RIFRA nasce da un'idea del GISMO per rispondere alla necessit\ue0 primaria di quantificare il
reale rischio fratturativo in Italia attraverso una specifica scheda e di valutare l'influenza delle
comorbilit\ue0 e delle terapie corelate al rischio di frattura. L'obiettivo secondario analizzare \a
percentuale di pazienti sottoposti a trattamento farmacologico in relazione ai valori densitometrici e
alle pregresse fratture, nonch\ue9 valutare la prevalenza di fratture da fragilit\ue0 nella popol azione in studio
The effectiveness of intra-articular injectionc of Hyalubrix combined with exercise therapy in the tratment of hip osteoarthritis
Purpose. Osteoarthritis (OA) is the most common joint
disorder in the elderly, causing significant pain which
negatively affects mobility and quality ol liie. The aim of
the study was to assess the effectiveness of ultrasound
\ucdmage-guided intra-articular injections of Hyalubrix@ combined
with exercise therapy in the treatment of hip osteoarthritis.
Methods. This was a single site, prosp\ue8ctive, open-fabel,
Investigator-initiated study. Forty patients rilere enrolled
and received three ultrasound image.guided injections
of Hyalubrix@, 45 days apart, combined with three sessions
a week of phys\uedcal therapy (proprioceptive rehabilitation
of the lower limbs; gait training; balance training)
up to a total of 30 sessions (10 weeks), starting from one
week after the first injection.
Results. The primary obiective was to achieve a lasting
reduction in OA symptoms related to pain during activity.
During the course of the study the pain perceived by
the patient during activity dropped from a mean value of
6.94 cm to a mean value of 1.46 cm and showed a statistically
significant decrease from visit 1 compared to
baseline (p < 0.05) which was confirmed at all the subsequent
time points. Significant improvements were also
observed in the evaluation of the secondary objectives:
hip disability; OA-related pain at rest; daily functioning
and NSAIDs intake.
Conclusions. Results from this study including 40 patients
for a total of 65 treated hips demonstrate a significant improvement in OA-related pain, hip disability, and
patient's daily functioning as well as a reduction in
NSAIDS intake. Patients suffering from hip OA s\ue8em to
benefil from the treatment wiih Hyalubrix@ injections
plus exercise therapy
Quorum of observables for universal quantum estimation
Any method for estimating the ensemble average of arbitrary operator
(observables or not, including the density matrix) relates the quantity of
interest to a complete set of observables, i.e. a quorum}. This corresponds to
an expansion on an irreducible set of operators in the Liouville space. We give
two general characterizations of these sets. All the known unbiased
reconstruction techniques, i.e. ``quantum tomographies'', can be described in
this framework. New operatorial resolutions are given that can be used to
implement novel reconstruction schemes.Comment: Latex, no figure
YF-12 cooperative airframe/propulsion control system program, volume 1
Several YF-12C airplane analog control systems were converted to a digital system. Included were the air data computer, autopilot, inlet control system, and autothrottle systems. This conversion was performed to allow assessment of digital technology applications to supersonic cruise aircraft. The digital system was composed of a digital computer and specialized interface unit. A large scale mathematical simulation of the airplane was used for integration testing and software checkout
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