455 research outputs found
Absence of Metal-Insulator-Transition and Coherent Interlayer Transport in oriented graphite in parallel magnetic fields
Measurements of the magnetoresistivity of graphite with a high degree of
control of the angle between the sample and magnetic field indicate that the
metal-insulator transition (MIT), shown to be induced by a magnetic field
applied perpendicular to the layers, does not appear in parallel field
orientation. Furthermore, we show that interlayer transport is coherent in less
ordered samples and high magnetic fields, whereas appears to be incoherent in
less disordered samples. Our results demonstrate the two-dimensionality of the
electron system in ideal graphite samples.Comment: 4 figures, details adde
Disminución en los parámetros espermáticos de ratones tratados con el extracto hidroalcohólico de Tropaeolum tuberosum “mashua”
In this work, we provided a Tropaeolum tuberosum hydroalcoholic extract to male mice (780 mg kg-1) for 7, 14 and 21 days treatment, there was no significant difference in body weight gain, testes, epididymides and prostate weight (p> 0.05), nevertheless progressive motility decreased and immobile sperm count increased significantly after 21 days treatment (p <0.05). The sperm count in the epididymis cauda decreased in the 3 three assessments, concentration on 21 days treatment was significantly lower than those of 7 and 14 days treatments (p <0.05). Our results suggest, that T. tuberosum has a direct action on the male reproductive system decreasing spermatic parameters without exerting toxic effects on mice.Se proporcionó extracto hidroalcohólico de Tropaeolum tuberosum a ratones machos (780 mg kg-1) durante 7, 14 y 21 días. Los tratamientos no produjeron diferencias significativas en la ganancia de peso corporal, y en el peso de los testículos, epidídimos y la próstata. Sin embargo, la movilidad progresiva espermática disminuyó y el recuento de espermatozoides inmóviles aumentó, ambos significativamente, después de 21 días de tratamiento (p <0.05). La concentración de espermatozoides en la cola del epidídimo disminuyó en las tres evaluaciones, la concentración espermática después de 21 días de tratamiento fue significativamente menor en comparación a 7 y 14 días de tratamiento (p <0.05). Nuestros resultados sugieren que T. tuberosum tiene una acción directa sobre el sistema reproductor masculino disminuyendo los parámetros espermáticos, sin ejercer efectos tóxicos en los ratones
First observational evidence of a North Madagascar Undercurrent
<i>In situ</i> observations reveal a southeastward-directed North Madagascar Undercurrent (NMUC) below and opposite to the equatorward-directed North Madagascar Current (NMC) off Cape Amber, at the northern tip of Madagascar. Results show an undercurrent hugging the continental slope with its core at 460 m depth and velocities over 0.7 m s-1. Its volume transport is estimated to be 3.1–3.8 Sv, depending on the velocity extrapolation methods used to fill in the data gaps near the slope (no-slip and full-slip, respectively). The thermohaline characteristics show a saltier and warmer NMUC, compared to the surrounding offshore waters, transporting mainly South Indian Central Water. Also, strong horizontal gradients of density are found in the NMUC domain. An inshore cell of coastal downwelling due to Ekman Transport toward the coast is identified, which can explain, at least in part, the strong baroclinic pressure gradients as well as the NMUC development and possible persistence
A new Tithonian (Upper Jurassic) marine vertebrate concentration Lagerstätte in north-eastern Mexico
Suppression subtractive hybridization analysis of genes regulated by magnaporthe oryzae infection in wheat adult plants.
Blast (also known as brusone), caused by the fungus Magnaporthe oryzae, is a serious disease of wheat (Triticum aestivum) across central and southern Brazil. The pathogen is a hemibiotrophic ascomycete that attacks several grass species. The disease was first described in rice in 1600 in China and it was reported infecting wheat ears in 1985 in Paraná state, Brazil, and since spread to all growing-regions in the country. Currently has been also reported on wheat fields in Bolivia, Paraguay and Argentina. The rice blast disease has emerged as a model for the study of phytopathogenic fungi showing that this pathogen initially colonizes host tissues as a biotroph, without causing detectable symptoms. Approximately 72?96 h after infection, lesions become apparent in the plant, characterizing the necrotrophic growth of M. oryzae. In wheat plants, depending on the developmental stage at which infection occurs blast can be devastating. Infected heads produce small and wrinkled grains with low specific weight. Few cultivars are described as resistant to wheat blast and fungicides have low control efficiency of the disease. Little is known about the molecular mechanism of wheat resistance to the pathogen. Here, we investigated the responses of wheat to M. oryzae infection in reproductive stage at 40 h after inoculation. The aim of this study was to identify genes that are differentially up- or downregulated in adults plants of Triticum aestivum infected with Magnaporthe oryzae. For this, we used a suppression subtractive hybridization (SSH) approach. A total of 420 high-quality contigs were isolated, 415 of them were mapped in Triticum aestivum genome. The 420 contigs were searched against the non-redundant nucleotide and protein databases in GenBank to predict the function for the corresponding genes. Fifty-five contigs corresponded to defense-related genes. We used the quantitative RT-PCR analysis to validate the differential expression patterns for 16 Triticum aestivum genes between control and inoculated spikes. Nine genes presented higher transcript levels under inoculation, including one gene previously described as responsive to Magnaporthe infection on wheat seedlings. This gene coding one protein membrane-associated that may increase the adhesion of the plasma membrane to the cell wall during pathogen infection. In contrast, the other 7 genes presented higher expression in mock-inoculated spikes. The study of these genes and the associated defense mechanisms can provide a significant advance in our understanding of the putative determinants of the resistance mechanisms of this wheat resistant genotype
Comment on "On the uncertainty relations and squeezed states for the quantum mechanics on a circle"
It is shown by examples that the position uncertainty on a circle, proposed
recently by Kowalski and Rembieli\'nski [J. Phys. A 35 (2002) 1405] is not
consistent with the state localization. We argue that the relevant
uncertainties and uncertainty relations (UR's) on a circle are that based on
the Gram-Robertson matrix. Several of these generalized UR's are displayed and
related criterions for squeezed states are discussed.Comment: 5 pages, LaTex2e, 3 figures.ep
Quantum mechanics on a circle: Husimi phase space distributions and semiclassical coherent state propagators
We discuss some basic tools for an analysis of one-dimensionalquantum systems
defined on a cyclic coordinate space. The basic features of the generalized
coherent states, the complexifier coherent states are reviewed. These states
are then used to define the corresponding (quasi)densities in phase space. The
properties of these generalized Husimi distributions are discussed, in
particular their zeros.Furthermore, the use of the complexifier coherent states
for a semiclassical analysis is demonstrated by deriving a semiclassical
coherent state propagator in phase space.Comment: 29 page
Las negociaciones y el concepto de valor
Abstract. In this paper the notions and the concepts related to value are laid out. The paper starts with an introduction and emphasizes the negotiations as the institutions of agreements. It stresses the social drive for the negotiation and particularly focuses on the human as a negotiator by nature. The article points out that value circles are in fact agreement circles.Key words: Negotiation, ValueResumen. En este trabajo se trata de dilucidar las nociones y conceptos relacionados con el aspecto de valor. La obra comienza con una introducción, y enfatiza la negociación como institución de acuerdos. También destaca la visión social de la negociación y acentúa el ser negociador por la naturaleza. Denota que las redes de valor son en realidad redes de acuerdos.Palabras Claves: Negociación, valo
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