Statistics of Core Lifetimes in Numerical Simulations of Turbulent, Magnetically Supercritical Molecular Clouds

We present measurements of the mean dense core lifetimes in numerical simulations of magnetically supercritical, turbulent, isothermal molecular clouds, in order to compare with observational determinations. "Prestellar" lifetimes (given as a function of the mean density within the cores, which in turn is determined by the density threshold n_thr used to define them) are consistent with observationally reported values, ranging from a few to several free-fall times. We also present estimates of the fraction of cores in the "prestellar", "stellar'', and "failed" (those cores that redisperse back into the environment) stages as a function of n_thr. The number ratios are measured indirectly in the simulations due to their resolution limitations. Our approach contains one free parameter, the lifetime of a protostellar object t_yso (Class 0 + Class I stages), which is outside the realm of the simulations. Assuming a value t_yso = 0.46 Myr, we obtain number ratios of starless to stellar cores ranging from 4-5 at n_thr = 1.5 x 10^4 cm^-3 to 1 at n_thr = 1.2 x 10^5 cm^-3, again in good agreement with observational determinations. We also find that the mass in the failed cores is comparable to that in stellar cores at n_thr = 1.5 x 10^4 cm^-3, but becomes negligible at n_thr = 1.2 x 10^5 cm^-3, in agreement with recent observational suggestions that at the latter densities the cores are in general gravitationally dominated. We conclude by noting that the timescale for core contraction and collapse is virtually the same in the subcritical, ambipolar diffusion-mediated model of star formation, in the model of star formation in turbulent supercritical clouds, and in a model intermediate between the previous two, for currently accepted values of the clouds' magnetic criticality.Comment: 25 pages, 8 figures, ApJ accepted. Fig.1 animation is at http://www.astrosmo.unam.mx/~e.vazquez/turbulence/movies/Galvan_etal07/Galvan_etal07.htm

Plan de desarrollo turístico comunitario para la parroquia El Sucre, cantón Patate, provincia de Tungurahua

La parroquia El Sucre ubicada en el cantón Patate, Provincia de Tungurahua, cuenta con potenciales turísticos lo cuales no han sido vistos como una oportunidad para lograr el desarrollo de la localidad, tampoco han sido promocionados ni mucho menos considerados para que se efectúe la actividad turística. Al ser considerado el Turismo Comunitario como una forma de dar a conocer los recursos naturales y culturales existentes en la parroquia, y ser una fuente generadora de ingresos que permite mejorar las condiciones de vida de la población se ha determinado la elaboración de la tesis que lleva por título de “PLAN DE DESARROLLO TURÍSTICO COMUNITARIO PARA LA PARROQUIA EL SUCRE, CANTON PATATE, PROVINCIA DE TUNGURAHUA”, con la finalidad de proponer una alternativa de desarrollo para las autoridades, así como para los habitantes de la localidad.The Sucre parish is located in Patate, in the Tungurahua Province, has the tourist potential which have not been seen as an opportunity for development of the town, have not been promoted much less considered to effect the tourism. Being considered the Community Tourism like a way to people know the natural and cultural resources that exist in the parish, and be a source of income that can improve the living conditions of the population has been determined that this thesis has the title of "TOURISM DEVELOPMENT PLAN FOR EL SUCRE PARISH COMMUNITY, IN PATATE, IN THE TUNGURAHUA PROVINCE", in order to propose an alternative development for authorities and for the locals

Elaborations on the String Dual to N=1 SQCD

In this paper we make further refinements to the duality proposed between N=1 SQCD and certain string (supergravity plus branes) backgrounds, working in the regime of comparable large number of colors and flavors. Using the string theory solutions, we predict different field theory observables and phenomena like Seiberg duality, gauge coupling and its running, the behavior of Wilson and 't Hooft loops, anomalous dimensions of the quark superfields, quartic superpotential coupling and its running, continuous and discrete anomaly matching. We also give evidence for the smooth interpolation between higgsed and confining vacua. We provide several matchings between field theory and string theory computations.Comment: 44 pages, 6 figures. References added, minor rewritings, published versio

Intraoperative coronary grafts flow measurement using the TTFM flowmeter: results from a domestic sample

OBJECTIVE: To evaluate intraoperative graft patency and identify grafts under risk of early occlusion. METHODS: Fifty four patients were submitted to coronary artery bypass surgery and the graft flow was assessed by the Flowmeter (Medtronic Medistim), which utilizes the TTFM method. Three patients had left main disease and 48 had normal or mildly reduced left ventricular function. RESULTS: In hospital mortality was 3.7% (two patients), one for mesenteric thrombosis and one due to cardiogenic chock. Seventeen patients (34%) were submitted to off pump CABG. Arterial Graft flow measures ranged from 8 to 106 ml/min (average 31.14 ml/min), and venous grafts flow ranged from 9 to 149 ml/min (average 50.42 ml/min). CONCLUSION: Flowmeter use represents higher safety both for patients and surgeons. Even under legal aspects, the documentation provided by the device can avoid future questionings.OBJETIVO: Avaliar a perviedade dos enxertos no intraoperatório e identificar enxertos com risco de oclusão precoce. MÉTODOS: Cinquenta e quatro pacientes foram submetidos à revascularização do miocárdio e foi utilizado o fluxômetro (Medtronic Medi-Stim) que utiliza o método de tempo de trânsito (TTFM) para avaliação do fluxo nos enxertos. Três pacientes tinham lesão de tronco de artéria coronária esquerda e 48 apresentavam função ventricular normal ou pouco comprometida. RESULTADOS: A mortalidade hospitalar foi de dois (3,7%) pacientes, um por trombose mesentérica e outro por choque cardiogênico. Dezessete (31,4%) pacientes foram operados sem circulação extracorpórea (CEC). O fluxo no enxerto arterial variou de 8 a 106 ml/min, com média de 31,14 ml/min, e nos enxertos venosos de 9 a 149 ml/min, com média de 50,42 ml/min. CONCLUSÃO: O fluxômetro representa maior segurança para o cirurgião e para o paciente. Até mesmo sob o aspecto legal essa documentação dos enxertos pérvios evitará questionamentos futuros.UNIFESP Hospital BandeirantesHospital BandeirantesUNIFESPInstituto de Cardiologia Dante PazzaneseUNIFESP, Hospital BandeirantesUNIFESPSciEL

Groundwater protection using vulnerability maps and wellhead protection area (WHPA). A case study in México

The need to protect groundwater resources against quality deterioration due to anthropogenic activities is unquestionable. The concept of aquifer pollution vulnerability maps and of wellhead protection areas (WHPA) as protection toolsis not new; however, in spite of the elapsed time, their use has been increased as a result of the increase in economic development—and everything that this entails—and the increase in prohibitive costs of treating contaminated water or of the decontamination of aquifers. The study’s objective was to establish an integrated method that defines, first of all, the areas of highest vulnerability in the aquifer, and second, within these areas, the wells that most urgently need protection. To identify these wells, additional criteria were taken, such as well constructive data, pumped volume, and the region’s socioeconomic characteristics (social exclusión index). Once the wells were ranked, several of them were chosen as a pilot study to compare different methods for the delineation of WHPA based on calculated fixed radius and analytical methods and, this way, identify which method or methods best adapt to the characteristics of the study area. The Minkin analytical method proved to offer the best results since it protects well on both sides and achieves a balance in the well’s upgradient distances. It is also worth mentioning that the delimitation of the WHPAs in the study area was limited in respect to hydrogeologic and technical data

Explotación intensiva del acuífero del Valle de Toluca: Análisis de algunos efectos económicos-ambientales

La indiscutible importancia de las aguas subterráneas en México está reflejada en el hecho de que el 50% del total del agua utilizada en la industria y el 70% del abastecimiento humano provienen de los acuíferos. Además, el mayor porcentaje (80%) de las extracciones de agua subterránea se destina a la agricultura. La necesidad de cubrir toda esta demanda ha dado lugar a una intensa explotación de los acuíferos con sus consiguientes impactos. En el presente trabajo se exponen algunos de estos impactos en uno de los acuíferos del Altiplano Mexicano, el correspondiente al Valle de Toluca. En particular, se estudiaron el efecto económico ocasionado por un mayor consumo de energía al tener que bombear agua a mayores profundidades a causa del descenso del nivel piezométrico y el impacto provocado por la aparición de agrietamientos originados por subsidencia de terreno. El impacto de los agrietamientos en el acuífero se valoró a través del estudio de la vulnerabilidad del acuífero a la contaminación. La vulnerabilidad determinada con el método SINTACS, con ayuda de un Sistema de Información Geográfica (SIG) desarrollado en ArcSIG ha mostrado el aumento del grado de vulnerabilidad (de Bajo a Alto) en áreas donde se identificaron los agrietamientos. Para dimensionar el impacto económico por abatimiento del nivel piezométrico se elaboraron mapas de curvas de isocostes, esta vez con el paquete informático IDRISI, que permitieron apreciar que la región más susceptible a incrementar los costes por bombeo es la zona centro (donde se localiza la ciudad de Toluca) mientras que en la zona poniente del acuífero se tiene la mayor tendencia a ahorros energéticos y por tanto de costes

Chiral symmetry breaking as open string tachyon condensation

We consider a general framework to study holographically the dynamics of fundamental quarks in a confining gauge theory. Flavors are introduced by placing a set of (coincident) branes and antibranes on a background dual to a confining color theory. The spectrum contains an open string tachyon and its condensation describes the U(N_f)_L x U(N_f)_R -> U(N_f)_V symmetry breaking. By studying worldvolume gauge transformations of the flavor brane action, we obtain the QCD global anomalies and an IR condition that allows to fix the quark condensate in terms of the quark mass. We find the expected N_f^2 Goldstone bosons (for m_q=0), the Gell-Mann-Oakes-Renner relation (for m_q small) and the \eta' mass. Remarkably, the linear confinement behavior for the masses of highly excited spin-1 mesons, m_n^2 ~ n is naturally reproduced.Comment: 30 pages + 5 appendices, 2 figure