3,846 research outputs found
Electrostatic Patch Effect in Cylindrical Geometry. III. Torques
We continue to study the effect of uneven voltage distribution on two close
cylindrical conductors with parallel axes started in our papers [1] and [2],
now to find the electrostatic torques. We calculate the electrostatic potential
and energy to lowest order in the gap to cylinder radius ratio for an arbitrary
relative rotation of the cylinders about their symmetry axis. By energy
conservation, the axial torque, independent of the uniform voltage difference,
is found as a derivative of the energy in the rotation angle. We also derive
both the axial and slanting torques by the surface integration method: the
torque vector is the integral over the cylinder surface of the cross product of
the electrostatic force on a surface element and its position vector. The
slanting torque consists of two parts: one coming from the interaction between
the patch and the uniform voltages, and the other due to the patch interaction.
General properties of the torques are described. A convenient model of a
localized patch suggested in [2] is used to calculate the torques explicitly in
terms of elementary functions. Based on this, we analyze in detail patch
interaction for one pair of patches, namely, the torque dependence on the patch
parameters (width and strength) and their mutual positions. The effect of the
axial torque is then studied for the experimental conditions of the STEP
mission.Comment: 28 pages, 6 Figures. Submitted to Classical Quantum Gravit
Study of the crossover transition of a gas of extended hadrons
We formulate a simple model for a gas of extended hadrons at zero chemical
potential by taking inspiration from the compressible bag model. We show that a
crossover transition qualitatively similar to lattice QCD can be reproduced by
such a system by including some appropriate additional dynamics. Under certain
conditions, at high temperature, the system consists of a finite number of
infinitely extended bags, which occupy the entire space. In this situation the
system behaves as an ideal gas of quarks and gluons.Comment: 2 pages, 1 figure - To appear in the conference proceedings for Quark
Matter 2009, March 30 - April 4, Knoxville, Tennesse
Crossover transition in bag-like models
We formulate a simple model for a gas of extended hadrons at zero chemical
potential by taking inspiration from the compressible bag model. We show that a
crossover transition qualitatively similar to lattice QCD can be reproduced by
such a system by including some appropriate additional dynamics. Under certain
conditions, at high temperature, the system consist of a finite number of
infinitely extended bags, which occupy the entire space. In this situation the
system behaves as an ideal gas of quarks and gluons.Comment: Corresponds to the published version. Added few references and
changed the titl
Particle Number Fluctuations in Statistical Model with Exact Charge Conservation Laws
Even though the first momenta i.e. the ensemble average quantities in
canonical ensemble (CE) give the grand canonical (GC) results in large
multiplicity limit, the fluctuations involving second moments do not respect
this asymptotic behaviour. Instead, the asymptotics are strikingly different,
giving a new handle in study of statistical particle number fluctuations in
relativistic nuclear reactions. Here we study the analytical large volume
asymptotics to general case of multispecies hadron gas carrying fixed baryon
number, strangeness and electric charge. By means of Monte Carlo simulations we
have also studied the general multiplicity probability distributions taking
into account the decay chains of resonance states.Comment: 4 pages, 2 figures. The report of the talk given in Strangeness in
Quark Matter 2004, Cape Town. Submitted to J. Phys. G: Nucl. Part. Phy
Thromboembolic events in patients treated with anti-angiogenic drugs
Induction of neo-angiogenesis is a fundamental step in many pathological conditions. The therapeutic value of inhibiting angiogenesis is an interesting area of research in oncology, with vascular endothelial growth factor (VEGF) being the most suitable anti-angiogenic target. In the last decade a number of anti-VEGF drugs have demonstrated, especially in combination with standard chemotherapy, clinical efficacy in the treatment of different solid tumor types. As data from clinical trials on anti-VEGF drugs are becoming available, it is increasingly recognized that VEGF, in addition to being a permeability, proliferation, and migration factor, is also a maintenance and protection factor for endothelial cells, being capable of regulating multiple biological functions, i.e. the production of vasoactive mediators and the expression of components of the thrombolytic and coagulation pathways. Consequently, the disturbance of vascular homeostasis by blocking VEGF may lead to endothelial dysfunction and adverse vascular effects, such as venous and arterial thromboembolic events. In preclinical models angiogenesis and the increased expression of VEGF has been associated to altered expression of proinflammatory genes. These genes may be regulated in a biphasic manner, and it is possible that anti-VEGF therapy may disrupt a negative feedback loop that leads to potential in situ thrombus formation. Accordingly, combination treatment with bevacizumab and chemotherapy, compared with chemotherapy alone, was recently associated with an increased risk of thromboembolism. The present review considers the biological mechanisms and clinical impact of thromboembolic complications during anti-angiogenic treatments in cancer patients
Pion Number Fluctuations and Correlations in the Statistical System with Fixed Isospin
The statistical system of pions with zero total isospin is studied. The
suppression effects for the average yields due to isospin conservation are the
same for , and . However, a behavior of the corresponding
particle number fluctuations are different. For neutral pions there is the
enhancement of the fluctuations, whereas for charged pions the isospin
conservation suppresses fluctuations. The correlations between the numbers of
charged and neutral pions are observed for finite systems. This causes a
maximum of the total pion number fluctuations for small systems. The
thermodynamic limit values for the scaled variances of neutral and charged
pions are calculated. The enhancements of the fluctuations due to Bose
statistics are found and discussed
Non-steroidal anti-inflammatory drugs in cancer prevention and therapy
Long-term use of non-steroidal anti-inflammatory drugs (NSAIDs) can be regarded as an effective approach for cancer chemoprevention, as demonstrated by a bulk of clinical and experimental evidence. However, the clinical use of these drugs as chemopreventive agents is limited by many open questions about the optimal drug, dose, duration of therapy and knowledge about the mechanism(s) by which these drugs act. In particular, the recent data on cardiovascular toxicity of coxibs has posed some limitations on the use of NSAIDs for cancer chemoprevention in the general population. The situation is different in certain genetically susceptible subgroups, such as in individuals with genetic mutations associated with hereditary nonpolyposis colon cancer (HNPCC) or familiar adenomatous polyps (FAP) in whom lifetime risk increases up to 70-90% and in whom the benefit of a chemopreventive drug might justify its use even in the presence of adverse effects
Non-steroidal anti-inflammatory drugs in cancer prevention and therapy
Long-term use of non-steroidal anti-inflammatory drugs (NSAIDs) can be regarded as an effective approach for cancer chemoprevention, as demonstrated by a bulk of clinical and experimental evidence. However, the clinical use of these drugs as chemopreventive agents is limited by many open questions about the optimal drug, dose, duration of therapy and knowledge about the mechanism(s) by which these drugs act. In particular, the recent data on cardiovascular toxicity of coxibs has posed some limitations on the use of NSAIDs for cancer chemoprevention in the general population. The situation is different in certain genetically susceptible subgroups, such as in individuals with genetic mutations associated with hereditary nonpolyposis colon cancer (HNPCC) or familiar adenomatous polyps (FAP) in whom lifetime risk increases up to 70-90% and in whom the benefit of a chemopreventive drug might justify its use even in the presence of adverse effects
Protective effects of exosomes derived from lyophilized porcine liver against acetaminophen damage on HepG2 cells
Background: Recently, extracellular vesicles have come to the fore following their emerging role in cell communication, thanks to their ability to reach cells into the human body without dissipating their cargo, transferring biological active molecules, such as proteins, nucleic acids, lipids, etc. They appear as a promising tool in medicine, because of their capability to modulate cellular response in recipient cells. Moreover, a considerable number of publications suggests that exosome uptake is selective but not specific, and it can cross species and cell-type boundaries. This study aims to explore the potential role of porcine liver derived extracellular vesicles, exosomes in particular, to protect human cells from acute damage induced by acetaminophen. Methods: Extracellular vesicles were isolated from porcine lyophilized liver using polymer-based precipitation and a further enrichment was performed using affinity beads. The effects of obtained fractions, total extracellular vesicles and enriched extracellular vesicles, were assessed on human liver derived HepG2 cells. Cell growth and survival were tested, with MTT and area coverage analysis designed by us, as well as protein expression, with immunofluorescence and Western blot. Oxidative stress in live cells was also measured with fluorogenic probes. Results: After proving that porcine extracellular vesicles did not have a toxic effect on HepG2, quite the contrary total extracellular vesicle fraction improved cell growth, we investigated their protective capability with a preconditioning strategy in APAP-induced damage. EVs displayed not only the ability to strongly modulate cell survival responses, but they also were able to boost cell cycle progression. Conclusions: Extracellular vesicles derived from farm animal food derivatives are able to modulate human hepatic cell metabolism, also improving cell survival in a damaged context
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