An optimal gap theorem

By solving the Cauchy problem for the Hodge-Laplace heat equation for $d$-closed, positive $(1, 1)$-forms, we prove an optimal gap theorem for K\"ahler manifolds with nonnegative bisectional curvature which asserts that the manifold is flat if the average of the scalar curvature over balls of radius $r$ centered at any fixed point $o$ is a function of $o(r^{-2})$. Furthermore via a relative monotonicity estimate we obtain a stronger statement, namely a `positive mass' type result, asserting that if $(M, g)$ is not flat, then $\liminf_{r\to \infty} \frac{r^2}{V_o(r)}\int_{B_o(r)}\mathcal{S}(y)\, d\mu(y)>0$ for any $o\in M$

Three-dimensional turbopump flowfield analysis

A program was conducted to develop a flow prediction method applicable to rocket turbopumps. The complex nature of a flowfield in turbopumps is described and examples of flowfields are discussed to illustrate that physics based models and analytical calculation procedures based on computational fluid dynamics (CFD) are needed to develop reliable design procedures for turbopumps. A CFD code developed at NASA ARC was used as the base code. The turbulence model and boundary conditions in the base code were modified, respectively, to: (1) compute transitional flows and account for extra rates of strain, e.g., rotation; and (2) compute surface heat transfer coefficients and allow computation through multistage turbomachines. Benchmark quality data from two and three-dimensional cascades were used to verify the code. The predictive capabilities of the present CFD code were demonstrated by computing the flow through a radial impeller and a multistage axial flow turbine. Results of the program indicate that the present code operated in a two-dimensional mode is a cost effective alternative to full three-dimensional calculations, and that it permits realistic predictions of unsteady loadings and losses for multistage machines

An?lisis comparativo de los dise?os curriculares de los programas en dise?o gr?fico en cuatro instituciones de educaci?n superior en colombia, para el a?o 2012

90 P?ginasEl problema de investigaci?n se plantea como un estudio comparativo entre varias propuestas curriculares, una primera delimitaci?n est? en los curr?culos a comparar. Sobrepasa a las capacidades log?sticas y de dedicaci?n en tiempo poder asumir la contrastaci?n curricular de los m?s de 40 programas de Dise?o Gr?fico que actualmente se ofertan en el pa?s, por esta raz?n se delimit? el estudio sobre algunas caracter?sticas b?sicas: tener en cuenta tanto universidades p?blicas como privadas, pensar en programas antiguos, de mediana constituci?n y de reciente constituci?n; se escogieron 4 universidades con las caracter?sticas anteriormente mencionadas. La conclusi?n es que el programa acad?mico de la CUN tiene una ventaja comparativa porque est? planteado en ciclos proped?uticos, lo que le brinda flexibilidad y pertinencia.ABSTRACT The research problem is presented as a comparative study of several proposed curricula, a first delimitation is to compare curricula. Surpasses logistics capabilities and dedication in time to take the matching curriculum of over 40 graphic design programs that are currently offered in the country, which is why the study was delimited on some basic characteristics: consider both public universities and private, think of old programs, middle and newly formed constitution, four universities were chosen with the above features. The conclusion is that the academic program of the CUN has a comparative advantage because it is raised in propaedeutic cycles, giving you flexibility and relevanceINTRODUCCION 12 1. PLANTEAMIENTO DEL PROBLEMA 14 1.1 DESCRIPCI?N DEL PROBLEMA 14 1.2 DELIMITACI?N DEL PROBLEMA DE INVESTIGACI?N. 14 1.3 PREGUNTAS DE INVESTIGACI?N 15 2. JUSTIFICACI?N 16 3. OBJETIVOS 18 3.1 OBJETIVO GENERAL 18 3.2 OBJETIVOS ESPEC?FICOS 18 4. ANTECEDENTES 19 4.1 HISTORIA DEL DISE?O GRAFICO EN COLOMBIA 19 5. MARCO DE REFERENCIA 37 5.1 DISE?O GR?FICO 37 5.1.1. Or?genes 37 5.1.2 El Dise?o Gr?fico Audiovisual Siglo XX 41 5.1.3 Dise?o Gr?fico Latinoamericano 42 5.2 LAS ARTES GR?FICAS EN EL SIGLO XX 44 5.3 NATURALEZA DEL CURR?CULO 45 5.3.1 Definici?n 45 5.3.2 Tendencias Curriculares 47 5.4 MARCO LEGAL. 51 6. DISE?O METODOL?GICO 53 6.1 TIPO DE INVESTIGACI?N 53 6.2 PARTICIPANTES 53 6.3 INSTRUMENTOS DE RECOLECCI?N DE INFORMACI?N 53 6.4 CRONOGRAMA 54 7. AN?LISIS COMPARATIVO DE LOS DISE?OS CURRICULARES DE LOS PROGRAMAS EN DISE?O GR?FICO EN CUATRO INSTITUCIONES DE EDUCACI?N SUPERIOR EN COLOMBIA, PARA EL A?O 2012 55 7.1 PERFILES DE LOS ACADEMICOS ENCARGADOS DE EJECUTAR EL CURRICULO. 55 7.2 DESARROLLO HIST?RICO DEL DISE?O GRAFICO EN COLOMBIA DESDE UNA PERSPECTIVA CURRICULAR. 56 10 7.3 PROYECCIONES DEL DISE?O GR?FICO EN COLOMBIA 58 7.4 APUESTA CURRICULAR 59 7.4.1 Perfiles Ocupaciones y Profesionales de los Egresados 59 7.4.2 Flexibilidad Curricular 61 7.4.3 Cr?ditos Acad?micos 71 8.4.4 Ciclos Proped?uticos 74 8.4.5. Procesos de Evaluaci?n 81 9. CONCLUSIONES 85 10. RECOMENDACIONES 86 REFERENCIAS 8

Preparation of Neutron-activated Xenon for Liquid Xenon Detector Calibration

We report the preparation of neutron-activated xenon for the calibration of liquid xenon (LXe) detectors. Gamma rays from the decay of xenon metastable states, produced by fast neutron activation, were detected and their activities measured in a LXe scintillation detector. Following a five-day activation of natural xenon gas with a Cf-252 (4 x 10^5 n/s) source, the activities of two gamma ray lines at 164 keV and 236 keV, from Xe-131m and Xe-129m metastable states, were measured at about 95 and 130 Bq/kg, respectively. We also observed three additional lines at 35 keV, 100 keV and 275 keV, which decay away within a few days. No long-lifetime activity was observed after the neutron activation.Comment: to be published in NIM A, corrected typos in Table 1 and Fig.6 of the previous versio

Non-minimal coupling of photons and axions

We establish a new self-consistent system of equations accounting for a non-minimal interaction of gravitational, electromagnetic and axion fields. The procedure is based on a non-minimal extension of the standard Einstein-Maxwell-axion action. The general properties of a ten-parameter family of non-minimal linear models are discussed. We apply this theory to the models with pp-wave symmetry and consider propagation of electromagnetic waves non-minimally coupled to the gravitational and axion fields. We focus on exact solutions of electrodynamic equations, which describe quasi-minimal and non-minimal optical activity induced by the axion field. We also discuss empirical constraints on coupling parameters from astrophysical birefringence and polarization rotation observations.Comment: 31 pages, 2 Tables; replaced with the final version published in Classical and Quantum Gravit