Catching the phantom: the MSSM on the Z6-orientifold

These lecture notes give a short introduction of the derivation of the supersymmetric standard model on the Z6-orientifold as published in hep-th/0404055. Untwisted and twisted cycles are constructed and one specific model is discussed in more detail.Comment: To appear in the proceedings of RTN Workshop on the Quantum Structure of Space-time and the Geometric Nature of Fundamental Interactions and EXT Workshop on Fundamental Interactions and the Structure of Spacetime, Kolymbari, Crete, Greece, 5-10 Sep 200

Tomographic Studies of the sQGP

Azimuthal correlation functions are used to study jet- and di-jet properties as a function of centrality in Au+Au collisions at $\sqrt{s_{_{\rm NN}}}$=200 GeV. Utilizing a novel technique to decompose the correlation function into a (di-)jet and an underlying event, the jet-pair distribution is extracted and compared to similar results for d+Au collisions obtained at the same collision energy. A striking similarity is observed between the widths and associated yields of the (di-)jet distributions for d+Au and peripheral Au+Au collisions. By contrast, the distributions for mid-central Au+Au collisions indicate an increase in the di-jet yield with centrality, and a very broad away-side jet having a possible minimum at $\Delta\phi \approx \pi$. These features point to significant medium induced modification to the away-side jet and are compatible with recent predictions of jet-induced "conical flow".Comment: Proc. 21st. Winter Workshop on Nuclear Dynamic

Parametric Analysis of the Selective Laser Sintering Process

Qualitative and quantitative analyses are required to develop Selective Laser Sintering into a viable Manufacturing process. A simplified mathematical model for sintering incorporating the heat tJ;ansfer equation. and the sintering rate equation, but using temperature independent thermal properties, is presented in this paper. A practical result is the calculation of sintering depthdeftned as the depth of powder where the void fraction is less than 0.1 as a function of control parameters, such as the laser power intensity, the laser scanning velocity, and the initial bedtemperature. We derive the general behavior of laser sintering. A comparison of model predictions with laser sinterlng tests is provided.Mechanical Engineerin

Decomposition of Harmonic and Jet Contributions to Particle-pair Correlations at Ultra-relativistic Energies

Methodology is presented for analysis of two-particle azimuthal angle correlation functions obtained in collisions at ultra-relativistic energies. We show that harmonic and di-jet contributions to these correlation functions can be reliably decomposed by two techniques to give an accurate measurement of the jet-pair distribution. Results from detailed Monte Carlo simulations are used to demonstrate the efficacy of these techniques in the study of possible modifications to jet topologies in heavy ion reactions.Comment: Updated version to be published in PRC Rapid Com

Escalas y medición de magnitudes no-métricas

La práctica de la medición mediante el uso de instrumentos alcanza en primera instancia a diversos aspectos del dominio físico y tardíamente se extiende al área de la investigación social, como secuela del interés por medir magnitudes no métricas del tipo de la inteligencia, las sensaciones, las actitudes, las opiniones En la presente contribución planeo discutir el sentido y alcance de la medición derivada del uso de escalas en la teorización psicosocial, recurriendo para ello a un análisis centrado en las escalas Likert

Plano oclusal en prótesis completa

Partiendo del concepto de plano ocIusal de la dentición natural, se define el de la prótesis completa, siendo el ideal el que se identifica con el que forman los dientes naturales. Con el fin de resaltar la importancia que tiene la correcta determinación del plano ocIusal en la boca edéntula, se expone la acción que desarrolla dentro del sistema estomatognático, en la fase de desarrollo y en la de adulto. El plano ocIusal aporta a la prótesis completa máxima eficacia masticatoria, estabilidad y confort. Se describe las referencias anatómicas para orientar y situar el plano ocIusal dentro de la boca desdentada

Estimating parameters of fluctuations in the cosmic microwave background

We address questions that arise in statistical analyses of recently detected fluctuations in the Cosmic Microwave Background (CMB). Estimators of the quadrupole amplitude, Q, and spectral index, n, of the CMB angular fluctuation power spectrum are considered. Families of unbiased estimators of Q2 and existence conditions for minimum variance estimators of n are given. We find that the common practice of excluding the quadrupole is not recommended if one is interested in unbiased estimators. We explain previousiy reported correlations of the estimators and show how they depend on the multiple used to normalize the spectrum. We show that a finite beam resolution does not justify the use of truncated least-squares to estimate harmonic coefficients of CMB data

Strategic behavior and efficiency in a groundwater pumping differential game

In this paper socially optimal and private exploitation of a common property aquifer are compared. Open-loop and feedback equilibria in nonlinear strategies have been computed to characterize the private solution. The use of these two equilibrium concepts aIlows us to distinguish between cost and strategic externalities. The open-Loop solution captures only the cost externality, whereas the feedback solution captures both externalities. The results show that strategic behavior increases the overexploitation of the aquifer compared to the open-loop solution. However, if the groundwater storage capacity is large, the difference between the socIally optImal and private exploitation, characterized by a feedback equilibrium, is negligible and can be ignored for practical purposes. En este trabajo se comparan la explotación privada y socialmente óptima de un acuífero de propiedad común. Para caracterizar la solución privada se han calculado los equilibrios' openloop' y 'feedback' en estrategias no lineales. El uso de estos dos conceptos de equilibrio nos ha permitido distinguir entre efectos externos estratégicos y de coste. La solución 'open-loop' captura solamente el efecto externo de los costes mientras que la SolucIón 'feedback' captura ambos efectos externos. Los resultados muestran que el comportamiento estratégico aumenta la sobreexplotación del acuífero comparado con la solución 'open-loop' o Sin embargo, si la capacidad de almacenamiento del acuífero es grande, la diferencia entre la explotación privada y la socialmente óptima, caracterizada por un equilibrio 'feedback', es despreciable y puede Ignorarse para propósitos prácticos.Explotación de aguas subterráneas, recursos de propiedad común, efecto externo estratégico, juegos diferenciales, solución 'feedback', estrategias no lineales Groundwater exploitation, common property resources, strategic externality, differential games, feedback solution, nonlinear strategies

Optimal growth and land preservation

A model of optimal economic growth with a constant population subject to a constraint on the availability of land is presented. It takes account of the dual character of land as a production factor and as a consumption good (environmental amenities) by determining the optimal intertemporal allocation of land between productive and recreational uses. An extension of the analysis for the case of a growing population with endogenous growth based on human capital accumulation shows that if the rate of discount is not very low then there exists a set of balanced growth paths compatible with a constant allocation of land. En este trabajo se presenta un modelo de crecimiento económico óptimo con una población constante sujeto a una restricción sobre la disponibilidad de tierra. En el modelo se tiene en cuenta el carácter dual de la tierra como factor productivo y como bien de consumo para usos recreacionales y se determina cual es la asignación intertemporal óptima de la tierra entre estos dos usos. En la segunda parte del trabajo, se presenta una extensión del análisis para el caso de una población creciente con crecimiento endógeno basado en la acumulación de capital humano y se demuestra que si la tasa de descuento no es muy pequeña existe un conjunto de sendas de crecimiento equilibrado compatibles con una asignación constante de la tierra.Crecimiento óptimo, asignación intertemporal de la tierra, preservación medioambiental, crecimiento de la población, crecimiento endógeno, capital humano Optimal growth, intertemporal land allocation, environmental preservation, population growth, endogenous growth, human capital

The self organizing map of neighbour stars and its kinematical interpretation

The Self-Organizing Map (SOM) is a neural network algorithm that has the special property ofcreating spatially organized tepresetüatioes of various features of input signals. The resulting maps resemble realneural structures found in the cortices of developed animal brains.: Also, the SOM. has been successful in various pattern recognition tasks involving noisy signals, as for instance, speech recognition and for this reason we are studying its application to some astronomical problems. In this paper w~ present the 2-D mapping and subsequerít study of one local sample of 12000 stars using SOM. The available attributes are 14: 3-D position and velocitiesvphotometric indexes, spectral type and luminosity class. The possible location of halo, thick disk and thin disk stars is discussed. Their kinematical properties are also compared using the velocity distribution moments up to order four.Peer ReviewedPostprint (published version