1,382 research outputs found
The production of matter from curvature in a particular linearized high order theory of gravity and the longitudinal response function of interferometers
The strict analogy between scalar-tensor theories of gravity and high order
gravity is well known in literature. In this paper it is shown that, from a
particular high order gravity theory known in literature, it is possible to
produce, in the linearized approch, particles which can be seen like massive
scalar modes of gravitational waves and the response of interferometers to this
type of particles is analyzed. The presence of the mass generates a
longitudinal force in addition of the transverse one which is proper of the
massless gravitational waves and the response of an arm of an interferometer to
this longitudinal effect in the frame of a local observer is computed. This
longitudinal response function is directly connected with the function of the
Ricci scalar in the particular action of this high order theory. Important
conseguences from a theoretical point of view could arise from this approach,
because it opens to the possibility of using the signals seen from
interferometers to understand which is the correct theory of gravitation.Comment: Accepted for Journal of Cosmology and Astroparticle Physic
Deceptive jugular manometry, blood colour and Po2 in the presence of an ipsilateral upper extremity arteriovenous fistula: a report of two cases
Manometry, blood gas analysis and colour of blood are often used as adjuncts to verify central venous access and rule out inadvertent arterial puncture. Several clinical scenarios may make these techniques unreliable. Two cases are presented involving patients with mature upper arm arteriovenous fistulas in which techniques to confirm correct central venous access contradicted ultrasound imaging findings.Keywords: arteriovenous fistula, central venous catheter, manometry, ultrasoun
Interferometer Response to Scalar Gravitational Waves
It was recently suggested that the magnetic component of Gravitational Waves
(GWs) is relevant in the evaluation of frequency response functions of
gravitational interferometers. In this paper we extend the analysis to the
magnetic component of the scalar mode of GWs which arise from scalar-tensor
gravity theory. In the low-frequency approximation, the response function of
ground-based interferometers is calculated. The angular dependence of the
electric and magnetic contributions to the response function is discussed.
Finally, for an arbitrary frequency range, the proper distance between two test
masses is calculated and its usefulness in the high-frequency limit for
space-based interferometers is briefly considered.Comment: Accepted for publication by Int. Journ. Mod. Phys. D. Final versio
Should Physical Activity Be Included in Nutrition Education? A Comparison of Nutrition Outcomes With and Without In-Class Activities
Limited-resource adults\u27 dietary intakes and nutrition behaviors improve as a result of Expanded Food and Nutrition Education Program (EFNEP)/Supplemental Nutrition Assistance Program Education (SNAP-Ed) participation; however, physical activity education is needed for improved health. The experimental study reported here assessed if spending time doing physical activity education affected dietary impact results and activity among participants. Standard dietary assessments showed no significant differences between groups, and interviews showed greater physical activity improvements/intentions by the experimental group, which suggests that nutrition education can be shortened 15-20 minutes for physical activity demonstrations to improve activity behaviors without adversely affecting nutrition-related behavioral improvements outcomes
Alcune note sulla geografia umana della Provincia Sardinia
Abstract - The recent discovery of some epigraphic artefacts in the countryside of Barumini and Siddi (Sardinia, Italy) is an opportunity to reflect on the Romanization of Sardinia. The new interpretation of CIL X, 7840 from Vallermosa, where the Fifenses are mentioned, and the identification of a new populus, the Barsanes (vel Barsani), allow us to put forward the proposal of a new cartography of Roman Sardinia. The epitaph of a colonus suggests an opportunity of going deeply into the question of Marmilla agrarian organization in the Roman age
---- [ITALIANO] Sommario - Il recente rinvenimento di alcuni manufatti epigrafici in agro di Siddi e Barumini sono l’occasione per una riflessione sulla romanizzazione della Sardegna. La rilettura di CIL X, 7840 da Vallermosa in cui vengono menzionati i Fifenses e l’individuazione di un nuovo populus, i Barsanes (vel Barsani) consentono di poter avanzare la proposta di una nuova cartografia su cui discutere. L’iscrizione di un colonus suggerisce lo spunto per un approfondimento dell’organizzazione agraria della Marmilla in età romana
Probe Without Moving Parts Measures Flow Angle
The measurement of local flow angle is critical in many fluid-dynamic applications, including the aerodynamic flight testing of new aircraft and flight systems. Flight researchers at NASA Dryden Flight Research Center have recently developed, flight-tested, and patented the force-based flow-angle probe (FLAP), a novel, force-based instrument for the measurement of local flow direction. Containing no moving parts, the FLAP may provide greater simplicity, improved accuracy, and increased measurement access, relative to conventional moving vane-type flow-angle probes. Forces in the FLAP can be measured by various techniques, including those that involve conventional strain gauges (based on electrical resistance) and those that involve more advanced strain gauges (based on optical fibers). A correlation is used to convert force-measurement data to the local flow angle. The use of fiber optics will enable the construction of a miniature FLAP, leading to the possibility of flow measurement in very small or confined regions. This may also enable the tufting of a surface with miniature FLAPs, capable of quantitative flow-angle measurements, similar to attaching yarn tufts for qualitative measurements. The prototype FLAP was a small, aerodynamically shaped, low-aspect-ratio fin about 2 in. (approximately equal to 5 cm) long, 1 in. (approximately equal to 2.5 cm) wide, and 0.125 in. (approximately equal to 0.3 cm) thick (see Figure 1). The prototype FLAP included simple electrical-resistance strain gauges for measuring forces. Four strain gauges were mounted on the FLAP; two on the upper surface and two on the lower surface. The gauges were connected to form a full Wheatstone bridge, configured as a bending bridge. In preparation for a flight test, the prototype FLAP was mounted on the airdata boom of a flight-test fixture (FTF) on the NASA Dryden F-15B flight research airplane
Stochastic background of relic scalar gravitational waves from scalar-tensor gravity
A stochastic background of relic gravitational waves is achieved by the so
called adiabatically-amplified zero-point fluctuations process derived from
early inflation. In principle, it provides a distinctive spectrum of relic
gravitational waves. In the framework of scalar-tensor gravity, we discuss the
scalar modes of gravitational waves and the primordial production of this
scalar component which is generated beside tensorial one. We discuss also the
upper limit for such a relic scalar component with respect to the WMAP
constraints.Comment: 7 pages, 1 figur
Some exact solutions of F(R) gravity with charged (a)dS black hole interpretation
In this paper we obtain topological static solutions of some kind of pure
gravity. The present solutions are two kind: first type is uncharged
solution which corresponds with the topological (a)dS Schwarzschild solution
and second type has electric charge and is equivalent to the
Einstein--conformally invariant Maxwell solution. In other word,
starting from pure gravity leads to (charged) Einstein- solutions
which we interpreted them as (charged) (a)dS black hole solutions of pure
gravity. Calculating the Ricci and Kreschmann scalars show that there is
a curvature singularity at . We should note that the Kreschmann scalar of
charged solutions goes to infinity as , but with a rate slower
than that of uncharged solutions.Comment: 21 pages, 4 figures, generalization to higher dimensions, references
adde
A precise response function for the magnetic component of Gravitational Waves in Scalar-Tensor Gravity
The important issue of the magnetic component of gravitational waves (GWs)
has been considered in various papers in the literature. From such analyses, it
resulted that such a magnetic component becomes particularly important in the
high frequency portion of the frequency range of ground based interferometers
for GWs which arises from standard General Theory of Relativity (GTR).
Recently, such a magnetic component has been extended to GWs arising from
Scalar-Tensor Gravity (STG) too. After a review of some important issues on GWs
in STG, in this paper we re-analyse the magnetic component in the framework of
STG from a different point of view, by correcting an error in a previous paper
and by releasing a more precise response function. In this way, we also show
that if one neglects the magnetic contribution considering only the
low-frequency approximation of the electric contribution, an important part of
the signal could be, in principle, lost. The determination of a more precise
response function for the magnetic contribution is important also in the
framework of the possibility to distinguish other gravitational theories from
GTR. At the end of the paper an expansion of the main results is also shown in
order to recall the presence of the magnetic component in GRT too.Comment: Accepted for publication in Physical Review D, to be published during
2011. 36 pages, in this second version typos have been corrected and
references have been update
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