117 research outputs found
Testing Non-commutative QED, Constructing Non-commutative MHD
The effect of non-commutativity on electromagnetic waves violates Lorentz
invariance: in the presence of a background magnetic induction field b, the
velocity for propagation transverse to b differs from c, while propagation
along b is unchanged. In principle, this allows a test by the Michelson-Morley
interference method. We also study non-commutativity in another context, by
constructing the theory describing a charged fluid in a strong magnetic field,
which forces the fluid particles into their lowest Landau level and renders the
fluid dynamics non-commutative, with a Moyal product determined by the
background magnetic field.Comment: 14 pages, LaTeX; minor corrections, references adde
mTOR and Tumor Cachexia.
Cancer cachexia affects most patients with advanced forms of cancers. It is mainly characterized by weight loss, due to muscle and adipose mass depletion. As cachexia is associated with increased morbidity and mortality in cancer patients, identifying the underlying mechanisms leading to cachexia is essential in order to design novel therapeutic strategies. The mechanistic target of rapamycin (mTOR) is a major intracellular signalling intermediary that participates in cell growth by upregulating anabolic processes such as protein and lipid synthesis. Accordingly, emerging evidence suggests that mTOR and mTOR inhibitors influence cancer cachexia. Here, we review the role of mTOR in cellular processes involved in cancer cachexia and highlight the studies supporting the contribution of mTOR in cancer cachexia
Spectrum of Schroedinger field in a noncommutative magnetic monopole
The energy spectrum of a nonrelativistic particle on a noncommutative sphere
in the presence of a magnetic monopole field is calculated. The system is
treated in the field theory language, in which the one-particle sector of a
charged Schroedinger field coupled to a noncommutative U(1) gauge field is
identified. It is shown that the Hamiltonian is essentially the angular
momentum squared of the particle, but with a nontrivial scaling factor
appearing, in agreement with the first-quantized canonical treatment of the
problem. Monopole quantization is recovered and identified as the quantization
of a commutative Seiberg-Witten mapped monopole field.Comment: 16 pages; references adde
Acidic tumor microenvironment abrogates the efficacy of mTORC1 inhibitors.
Blocking the mechanistic target of rapamycin complex-1 (mTORC1) with chemical inhibitors such as rapamycin has shown limited clinical efficacy in cancer. The tumor microenvironment is characterized by an acidic pH which interferes with cancer therapies. The consequences of acidity on the anti-cancer efficacy of mTORC1 inhibitors have not been characterized and are thus the focus of our study.
Cancer cell lines were treated with rapamycin in acidic or physiological conditions and cell proliferation was investigated. The effect of acidity on mTORC1 activity was determined by Western blot. The anticancer efficacy of rapamycin in combination with sodium bicarbonate to increase the intratumoral pH was tested in two different mouse models and compared to rapamycin treatment alone. Histological analysis was performed on tumor samples to evaluate proliferation, apoptosis and necrosis.
Exposing cancer cells to acidic pH in vitro significantly reduced the anti-proliferative effect of rapamycin. At the molecular level, acidity significantly decreased mTORC1 activity, suggesting that cancer cell proliferation is independent of mTORC1 in acidic conditions. In contrast, the activation of mitogen-activated protein kinase (MAPK) or AKT were not affected by acidity, and blocking MAPK or AKT with a chemical inhibitor maintained an anti-proliferative effect at low pH. In tumor mouse models, the use of sodium bicarbonate increased mTORC1 activity in cancer cells and potentiated the anti-cancer efficacy of rapamycin. Combining sodium bicarbonate with rapamycin resulted in increased tumor necrosis, increased cancer cell apoptosis and decreased cancer cell proliferation as compared to single treatment.
Taken together, these results emphasize the inefficacy of mTORC1 inhibitors in acidic conditions. They further highlight the potential of combining sodium bicarbonate with mTORC1 inhibitors to improve their anti-tumoral efficacy
Frequency behavior of Raman coupling coefficient in glasses
Low-frequency Raman coupling coefficient of 11 different glasses is
evaluated. It is found that the coupling coefficient demonstrates a universal
linear frequency behavior near the boson peak maximum and a superlinear
behavior at very low frequencies. The last observation suggests vanishing of
the coupling coefficient when frequency tends to zero. The results are
discussed in terms of the vibration wavefunction that combines features of
localized and extended modes.Comment: 8 pages, 9 figure
Testing spatial noncommutativiy via the Aharonov-Bohm effect
The possibility of detecting noncommutative space relics is analyzed using
the Aharonov-Bohm effect. We show that, if space is noncommutative, the
holonomy receives non-trivial kinematical corrections that will produce a
diffraction pattern even when the magnetic flux is quantized. The scattering
problem is also formulated, and the differential cross section is calculated.
Our results can be extrapolated to high energy physics and the bound is found. If this bound holds, then noncommutative
effects could be explored in scattering experiments measuring differential
cross sections for small angles. The bound state Aharonov- Bohm effect is also
discussed.Comment: 16 pp, Revtex 4, 2 fig, new references added. To appear in PR
Noncommutative Fluids
We review the connection between noncommutative gauge theory, matrix models
and fluid mechanical systems. The noncommutative Chern-Simons description of
the quantum Hall effect and bosonization of collective fermion states are used
as specific examples.Comment: To appear in "Seminaire Poincare X", Institut Henri Poincare, Paris;
references adde
The definition of the European Almond Core collection
The European project 068 AGRI GEN RES 870/2004 has as an aim the definition of the European almond core collection. The methodology for creation of any core collection has to define how best to select entries using complex and incomplete accession data, as well as how and when to revise these decisions over time. The acquisition of data has been based on specific varietal descriptors, including morphological, physiological, phytopathological, genetic and chemical traits, following the descriptors defined by IBPGR/Bioversity, UPOV and the ECP/GR Prunus Working Group. Newly defined traits, not included in these descriptors, have also been considered because they are very important in defining the range of variability of the species. These traits include chilling and heat requirements for blooming, the molecular markers for genotype identification and the different chemical components of the kernel, as possible parameters for defining almond quality. As a result, a strategy to define the almond core collection was identified by highlighting the main steps to achieve in the near future.Peer ReviewedPrunus amygdalus Batschcore collectiongenetic resourcesgermplasmPublishe
Proyecto europeo para la valorización de recursos genéticos autóctonos de almendro y avellano. Trabajos realizados en España
Publishe
As múltiplas funções da agricultura familiar: um estudo no assentamento Monte Alegre, região de Araraquara (SP).
A partir da emergência da ideia de sustentabilidade, a agricultura adquiriu novas conotações, associadas não apenas ao aspecto produtivo, mas também à conservação dos recursos naturais e dos territórios rurais, em um reconhecimento de sua multifuncionalidade. Com base nesta noção, que valoriza as funções socioambientais desempenhadas pelas famílias rurais e pelas agriculturas praticadas, o presente artigo analisa um assentamento rural no estado de São Paulo, buscando identificar quais são e de que forma se expressam as funções para além da produção neste território particular. Por meio de uma metodologia de cunho quali-quantitativo, observou-se que, no assentamento em foco, a agricultura encerra em si questões de coesão territorial, manutenção da segurança alimentar, conservação da agrobiodiversidade e de fomento a outras atividades produtivas, sendo o elemento central da reconstrução de um modo de vida rural neste ambiente
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