1,003 research outputs found
The Effects of Boxy/Peanut Bulges on Galaxy Models
We examine the effects that the modelling of a Boxy/Peanut (B/P) bulge will
have on the estimates of the stellar gravitational potential, forces, orbital
structure and bar strength of barred galaxies. We present a method for
obtaining the potential of disc galaxies from surface density images, assuming
a vertical density distribution (height function), which is let to vary with
position, thus enabling it to represent the geometry of a B/P. We construct a
B/P height function after the results from a high-resolution, N-body+SPH
simulation of an isolated galaxy and compare the resulting dynamical model to
those obtained with the commonly used, position-independent "flat" height
functions. We show that methods that do not allow for a B/P can induce errors
in the forces in the bar region of up to 40% and demonstrate that this has a
significant impact on the orbital structure of the model, which in turn
determines its kinematics and morphology. Furthermore, we show that the bar
strength is reduced in the presence of a B/P. We conclude that neglecting the
vertical extent of a B/P can introduce considerable errors in the dynamical
modelling. We also examine the errors introduced in the model due to
uncertainties in the parameters of the B/P and show that even for generous but
realistic values of the uncertainties, the error will be noticeably less than
that of not modelling a B/P bulge at all.Comment: Accepted for publication in MNRA
Progress towards Bell-type polarization experiment with thermal neutrons
Experimental tests of Bell-type inequalities distinguishing between quantum
mechanics and local realistic theories remain of considerable interest if
performed on massive particles, for which no conclusive result has yet been
obtained. Only two-particle experiments may specifically test the concept of
spatial nonlocality in quantum theory, whereas single-particle experiments may
generally test the concept of quantum noncontextuality. Here we have performed
the first Bell-type experiment with a beam of thermal-neutron pairs in the
singlet state of spin, as originally suggested by J. S. Bell. These
measurements confirm the quantum-theoretical predictions, in agreement with the
results of the well-known polarization experiments carried out on optical
photons years ago
Quantum electrodynamical torques in the presence of Brownian motion
Quantum fluctuations of the electromagnetic field give rise to a zero-point energy that persists even in the absence of electromagnetic sources. One striking consequence of the zero-point energy is manifested in the Casimir force, which causes two electrically neutral metallic plates to attract in order to reduce the zero-point energy. A second, less well-known, effect is a torque that arises between two birefringent materials with in-plane optical anisotropy as a result of the zero-point energy. In this paper, we discuss the influence of Brownian motion on two birefringent plates undergoing quantum electrodynamical (QED) rotation as a result of the system's zero-point energy. Direct calculations for the torque are presented, and preliminary experiments are discussed. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft
STUDIO SULL'EFFICACIA DELLA TERAPIA ANTICOAGULANTE NEI PAZIENTI CON TROMBOSI PORTALE AFFETTI DA CIRROSI EPATICA
Background & Aims:
Portal Vein thrombosis defines the presence of a thrombus, blocking completely or partially the vein in the trunck of the portal vein or in its intrahepatic collaterals .
For patients whit cirrhosis, it means a preexisting HYPERLINK "http://www.ncbi.nlm.nih.gov/pubmed?term=hypertension%20portal&cmd=correctspelling" portal hypertension getting worth adding a presinusoidal part to it. The TP, if complete, can block the liver transplantation.
The aim of this study is to check the efficiency of the anticoagulant oral therapy with heparina in a group of patients affected with epathic cyrrhosis or TP, to value the symptoms of occurances of the TP and the variations of the Child-Pugh score according to the appearance of the resolution or the eventual extension of the TP.
Methods:
This study has been established in a consecutive range of 66 patients enroled retrospectively, affected with CE and trombose of the Portal system, referred to our unit from January 1996 and April 2010. These patients were followed whit blood exams, abdomen ultrasound computerized axial tomogrphy,endoscopy.
Results:
At the time of the TP diagnosis, 17% of the patients belonged to the Child-Pugh A class, 68% to the Child-Pugh B class and 6% to the Child-Pugh C class.
44 Patients (66,7%) has done anticoagulant oral therapy, 17(39%) patients were following the terapia con eparina a basso peso molecolare, 23(52%) patients were following a therapy with Coumadin and 4(9%) were following both therapy alternatively.
Average time of treatment was 38 \ub1 4 months for the group taking Coumadin, 23 \ub1 3 months for the group taking Eparina a basso peso molecolare. 2 patients were taking eparina for 8 \ub1 1 months and then 39 \ub1 15 months. 2 patients were taking Coumadin for 5 \ub1 2 months and then eparina for 13 \ub1 5 mesi.
During the follow-up, 24 patients out of 66 (36%) have obtained a complete resolution( 4 patients without therapy and 20 taking an anticoagulant treatment : 4 patients in therapy with heparin, 12 patients with Coumadin, 4 patients with both simultaneously.)
The partial recanalization was obtained for 28 patients (42%) (4 patients without therapy, 24 patients under an anticoagulant therapy : 8 patients following a therapy with heparin, 14 following a therapy with Coumadin and 2 following both at the same time.
We can observe an extansion for the trombose for 31 patients out of 66 (47%) from which 25 outside of the anticoagulant therapy and 6 during it (2 patients following the heparin therapy, 3 patients with Coumadin and 1 patient following both simultaneously.
20 patients had portal cavernous (for 7 patients it was already diagnosed, for 13 patients it appeared during the follow-up from which 4 patients were not following any therapy, 5 an heparin therapy, 3 an Coumadin therapy and 1 both simultaneously.
Conclusions:
The anticoagulant therapy were proved efficient in the recanalization of the TP during the follow-up (p=0,032).
The anticoagulant therapy were proved efficient in the partial recanalization of the portal vein thrombosis (p=0,018).
Undertaking the anticoagulant therapy did not have a significative impact on the progression of portal vein thrombosis (p=0,168) at the follow-up.
The anticoagulant therapy did not prevent the develop of caverous (p=0,741)
Further evidence of antibunching of two coherent beams of fermions
We describe an experiment confirming the evidence of the antibunching effect
on a beam of non interacting thermal neutrons. The comparison between the
results recorded with a high energy-resolution source of neutrons and those
recorded with a broad energy-resolution source enables us to clarify the role
played by the beam coherence in the occurrence of the antibunching effect.Comment: 4 pages, 3 figure
Direct experimental evidence of free fermion antibunching
Fermion antibunching was observed on a beam of free noninteracting neutrons.
A monochromatic beam of thermal neutrons was first split by a graphite single
crystal, then fed to two detectors, displaying a reduced coincidence rate. The
result is a fermionic complement to the Hanbury Brown and Twiss effect for
photons.Comment: 4 pages, 2 figure
Isolated Pulmonary Valve Endocarditis.
Infective endocarditis involving the right side of the heart is typically associated with IV drug abuse and chronic indwelling catheters which commonly involve the tricuspid valve. Isolated pulmonary valve endocarditis (PVE) is a rare clinical entity. We report a rare case of a young woman with a history of end-stage renal disease (ESRD) on hemodialysis through tunneled catheter presenting with persistent coagulase-negative staphylococcus (CoNS) epidermidis bacteremia despite being on appropriate treatment with IV vancomycin for two weeks. Because of the persistent bacteremia, a transesophageal echocardiogram was performed and it revealed a thickened pulmonary valve with 1.8 cm vegetation in the left posterior cusp. She was successfully treated with IV daptomycin course for a total of six weeks. The recommended management for PVE is usually medical treatment with IV antibiotics gauged according to sensitivities of the cultures. Our article highlights the fact that the decision to manage it medically versus surgically can propose a challenge as the guidelines are not very robust
A paraoxonase gene polymorphism, PON 1 (55), as an independent risk factor for increased carotid intima-media tickness in middle-aged women.
The role of somatic maturation on bioimpedance patterns and body composition in male elite youth soccer players
The purpose of this study was to examine the influence of chronological age (CA) and somatic maturation on body composition (BC) and bioimpedance parameters in male elite soccer players. BC and bioimpedance variables were measured in a sample of 249 players aged 9 1218 years of age and registered in two professional Italian soccer teams. Results from segmental analysis showed transition time points where the influence of CA and somatic maturation on bioimpedance patterns and BC characteristics increased or subsided. The accelerated phases were assessed for fat free mass, total body water, and upper muscle area, with a starting time point at approximately 122.00 years from peak at velocity (YPHV), and for body cell mass, whose developmental tempo sped up around 121.00 YPHV. An increase in the rate of development was also observed close to 122.00 YPHV for phase angle (PA), although without accelerated phases. From a CA point of view, significant slope changes were found for all BC and bioimpendance variables, except for the calf muscle area. Although the starting points and the span of the accelerated phases were different, they subsided or disappeared at ~15 years, except for PA, whose growth waned at ~17 years
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