7,343 research outputs found
Impact of temperature dependence of the energy loss on jet quenching observables
The quenching of jets (particles with ) in
ultra-relativistic heavy-ion collisions has been one of the main prediction and
discovery at RHIC. We have studied, by a simple jet quenching modeling, the
correlation between different observables like the nuclear modification factor
\Rapt, the elliptic flow and the ratio of quark to gluon suppression
. We show that the relation among these
observables is strongly affected by the temperature dependence of the energy
loss. In particular the large and and the nearly equal \Rapt of quarks
and gluons can be accounted for only if the energy loss occurs mainly around
the temperature and the flavour conversion is significant.Finally we
point out that the efficency in the conversion of the space eccentricity into
the momentum one () results to be quite smaller respect to the one coming
from elastic scatterings in a fluid with a viscosity to entropy density ratio
.Comment: 7 pages, 8 figures, Workshop WISH 201
Ultrasound Guidance in Paravertebral Injections of Oxygen-Ozone: Treatment of Low Back Pain
Background: Paravertebral injection of ozone is an established clinical practice for the treatment of Low Back Pain (LBP). The role of Ultrasound Guidance (USG) in mini invasive procedures has become important in many clinical practice thanks to the greater precision this technique can add. As matter of fact, a large volume of ozone in a single administration may have some adverse or side effects. In this study we wanted to verify if the use of USG in Oxygen/ Ozone (O2/O3) infiltrations could allow the administration of a smaller volume of gas mixture, increasing the safety and the comfort of the procedure itself, obtaining however similar or better results in pain decrease.
Methods: We compared two groups of 25 patients affected by LBP, undergoing 10 infiltrations of O2/O3, by using USG (group U) or only anatomical landmarks (group AL). Pain intensity, by calculating Visual Analogical Scale (VAS) difference before and after the treatment, and the discomfort were evaluated in both groups.
Results: The mean of the VAS before the treatment was 6.44 in group U and 6.48 in group AL. The mean of the VAS after the treatment was 2.22 in group U and 3.04 in group AL. The mean of discomfort rate was 2.84 in group U and 5.44 in group AL. The number of patients with unbearable discomfort was 0 in group U and 7 in group AL.
Conclusions: As many other treatment, also paravertebral injections of O2/O3 benefits of the advantages of the US device which makes this treatment safer and more accurate
Fast inactivation in Shaker K+ channels. Properties of ionic and gating currents.
Fast inactivating Shaker H4 potassium channels and nonconducting pore mutant Shaker H4 W434F channels have been used to correlate the installation and recovery of the fast inactivation of ionic current with changes in the kinetics of gating current known as "charge immobilization" (Armstrong, C.M., and F. Bezanilla. 1977. J. Gen. Physiol. 70:567-590.). Shaker H4 W434F gating currents are very similar to those of the conducting clone recorded in potassium-free solutions. This mutant channel allows the recording of the total gating charge return, even when returning from potentials that would largely inactivate conducting channels. As the depolarizing potential increased, the OFF gating currents decay phase at -90 mV return potential changed from a single fast component to at least two components, the slower requiring approximately 200 ms for a full charge return. The charge immobilization onset and the ionic current decay have an identical time course. The recoveries of gating current (Shaker H4 W434F) and ionic current (Shaker H4) in 2 mM external potassium have at least two components. Both recoveries are similar at -120 and -90 mV. In contrast, at higher potentials (-70 and -50 mV), the gating charge recovers significantly more slowly than the ionic current. A model with a single inactivated state cannot account for all our data, which strongly support the existence of "parallel" inactivated states. In this model, a fraction of the charge can be recovered upon repolarization while the channel pore is occupied by the NH2-terminus region
A model for assembly sequence planning in a multirobot environment
2002 IFAC15th Triennial World Congress, Barcelona, SpainThis paper presents a model for the selection of optimal assembly sequences for a product in multirobot systems. The objective of the plan is the minimization of the total assembly time (makespan). To meet this objective, the model takes into account, in addition to the assembly times and resources for each task, the times needed to change tools in the robots, and the delays due to the transportation of intermediate subassemblies between different machines. An A* algorithm that solves the problem is also presented, which starts from the And/Or graph for the product (compressed representation of all feasible assembly plans)
On Fabry P\'erot Etalon based Instruments. I. The Isotropic Case
Here we assess the spectral and imaging properties of Fabry P\'erot etalons
when located in solar magnetographs. We discuss the chosen configuration
(collimated or telecentric) for both ideal and real cases. For the real cases,
we focus on the effects caused by the polychromatic illumination of the filter
by the irregularities in the optical thickness of the etalon and by deviations
from the ideal illumination in both setups. We first review the general
properties of Fabry P\'erots and we then address the different sources of
degradation of the spectral transmission profile. We review and extend the
general treatment of defects followed by different authors. We discuss the
differences between the point spread functions (PSFs) of the collimated and
telecentric configurations for both monochromatic and (real)
quasi-monochromatic illumination of the etalon. The PSF corresponding to
collimated mounts is shown to have a better performance, although it varies
from point to point due to an apodization of the image inherent to this
configuration. This is in contrast to the (perfect) telecentric case, where the
PSF remains constant but produces artificial velocities and magnetic field
signals because of its strong spectral dependence. We find that the unavoidable
presence of imperfections in the telecentrism produces a decrease of flux of
photons and a shift, a broadening and a loss of symmetrization of both the
spectral and PSF profiles over the field of view, thus compromising their
advantages over the collimated configuration. We evaluate these effects for
different apertures of the incident beam.Comment: 20 pages 22 figures 2 Appendice
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