Library of medium-resolution fiber optic echelle spectra of F, G, K, and M field dwarfs to giants stars

We present a library of Penn State Fiber Optic Echelle (FOE) observations of a sample of field stars with spectral types F to M and luminosity classes V to I. The spectral coverage is from 3800 AA to 10000 AA with nominal a resolving power 12000. These spectra include many of the spectral lines most widely used as optical and near-infrared indicators of chromospheric activity such as the Balmer lines (H_alpha, H_beta), Ca II H & K, Mg I b triplet, Na I D_{1} and D_{2}, He I D_{3}, and Ca II IRT lines. There are also a large number of photospheric lines, which can also be affected by chromospheric activity, and temperature sensitive photospheric features such as TiO bands. The spectra have been compiled with the goal of providing a set of standards observed at medium resolution. We have extensively used such data for the study of active chromosphere stars by applying a spectral subtraction technique. However, the data set presented here can also be utilized in a wide variety of ways ranging from radial velocity templates to study of variable stars and stellar population synthesis. This library can also be used for spectral classification purposes and determination of atmospheric parameters (T_eff, log{g}, [Fe/H]). A digital version of all the fully reduced spectra is available via ftp and the World Wide Web (WWW) in FITS format.Comment: Latex file with 17 pages, 4 figures. Full postscript (text and figures) available at http://www.ucm.es/info/Astrof/fgkmsl/FOEfgkmsl.html To be published in ApJ

Pezoa Véliz, poeta social

Indexación: Revista UNABEl artículo podría titularse también Pezoa Véliz modernista, Pezoa Véliz poeta popular, Pezoa Véliz, poeta nacional, etc. porque el autor poseía múltiples facetas temáticas, de tono y de estilo. Se prefirió calificarlo como poeta social en atención a la índole de sus poemas más representativos. Pezoa Véliz vivió menos de 30 años a principios del siglo XX y no pudo alcanzar, por condiciones socio-económicas, una educación sistemática superior. Su gran modelo poético es Rubén Darío y sus logros son muy irregulares. Es poeta más de antología breve que de obras completas. En el grupo más escogido de sus poemas hay algunos como "Tarde en el hospital" que pueden parangonarse con los más logrados de la poesía chilena. Abstract: This article could be also called Pezoa Veliz modemist, popular poet Pezoa Veliz, national poet Pezoa Veliz, etc. cause the author had multiple topics, from tone and style. It rather called him as a social poet ín attention to the nature ofhis most representative poems. Pezoa Veliz Iived less than 30 year at the begínníng of the XXth century and he couldn't continue, for his socio economic conditions, to a superior sistematic education. His great poetic role is Ruben Dario and his achivements are pretty irregular. He's a poet more like anthology than complete pieces ofwork. In the selected group ofhis poems there are some as "Aftemoon ín the hospital" ("Tarde en el hospital") that can be compared with some ofthe best achievements ofthe chilean poetry

Cost recovery and pricing of payment services

A modern payment system is essential for promoting domestic and international trade and exchange as well as developing financial markets. Payment users will be directed toward the most efficient payment methods when the costs of producing those services are reflected in the prices paid. Resources are being wasted in the United States because consumers see no important difference in transaction prices or bank costs between using a check or using electronic direct debit in paying a bill, even though the social costs of these two instruments are different. Electronic payments cost only a third to half as much as paper-based payments. An estimated $100 billion (or 1.5 percent of GDP) is being lost by the continued use of paper-based checks. When payment instruments are not appropriately priced, the costs must be covered elsewhere. One common solution is to let loan revenues cover part of payment expenses (keeping loan rates higher to compensate). When prices reflect the full cost of producing the service, users demand the services that use the fewest real resources. The authors give examples of payment prices and price schedules and show how underlying cost data are used to"build up"to a price. They outline how payment services may best be structured to: a) Appropriately reflect economies of scale or scope in the production of payment services; b) Adjust cost recovery percentages to accommodate how much demand conditions associated with start-up differ from those associated with mature operation. (During a new system's early years of operation, the transaction volume may be low and some form of underrecovery of costs may be required to encourage use of the system. But any such underrecovery must be built into future pricing arrangements oncethe systems are established and traffic volumes are at a level where full cost recovery is practical. To ensure fairness, the pricing structure must also guarantee that latecomers to the system not get more favorable treatment than the initial user group.); and c) Induce efficient use of scarce resources. They note the economic principles that recommend certain pricing methods over others and apply equally to payment services provided by the private sector or through a government agency. They show why costs should be recovered through user transaction fees.Banks&Banking Reform,Payment Systems&Infrastructure,Economic Theory&Research,Markets and Market Access,Decentralization,Payment Systems&Infrastructure,Economic Theory&Research,Banks&Banking Reform,Environmental Economics&Policies,Markets and Market Access

On the collapse in fourth order gravities

The gravitational collapse in fourth order theories of gravity defined by an arbitrary action of the scalar curvature shows significant deviations with General Relativity. The presence of a new scalar mode produces a higher initial contraction that favors the reduction of the collapsing time. However, depending on the particular model, there are fundamental differences when the modifications to the General Relativity collapse leave the linear regime. These analyses can be used to exclude an important region of the parameter space associated with alternative gravitational models.Comment: 4 pages, 2 figures, Contribution to the Proceedings of Spanish Relativity Meeting ERE2011, Madrid 201

Chromospheric activity and rotation of FGK stars in the solar vicinity. An estimation of the radial velocity jitter

Context: Chromospheric activity produces both photometric and spectroscopic variations that can be mistaken as planets. Large spots crossing the stellar disc can produce planet-like periodic variations in the light curve of a star. These spots clearly affect the spectral line profiles and their perturbations alter the line centroids creating a radial velocity jitter that might contaminate" the variations induced by a planet. Precise chromospheric activity measurements are needed to estimate the activity-induced noise that should be expected for a given star. Aims: We obtain precise chromospheric activity measurements and projected rotational velocities for nearby (d < 25 pc) cool (spectral types F to K) stars, to estimate their expected activity-related jitter. As a complementary objective, we attempt to obtain relationships between fluxes in different activity indicator lines, that permit a transformation of traditional activity indicators, i.e, CaII H & K lines, to others that hold noteworthy advantages. Methods: We used high resolution (~50000) echelle optical spectra. To determine the chromospheric emission of the stars in the sample, we used the spectral subtraction technique. Rotational velocities were determined using the cross-correlation technique. To infer activity-related radial velocity (RV) jitter, we used empirical relationships between this jitter and the R'_HK index. Results: We measured chromospheric activity, as given by different indicators throughout the optical spectra, and projected rotational velocities for 371 nearby cool stars. We have built empirical relationships among the most important chromospheric emission lines. Finally, we used the measured chromospheric activity to estimate the expected RV jitter for the active stars in the sample.Comment: Accepted for publication in Astronomy & Astrophysic

Quantization of massive scalar fields over static black string backgrounds

The renormalized mean value of the corresponding components of the Energy-Momentum tensor for massive scalar fields coupled to an arbitrary gravitational field configuration having cylindrical symmetry are analytically evaluated using the Schwinger-DeWitt approximation, up to second order in the inverse mass value. The general results are employed to explicitly derive compact analytical expressions for the Energy-Momentum tensor in the particular background of the Black-String spacetime. In the case of the Black String considered in this work, we proof that a violation of the weak energy condition occur at the horizon of the space-time for values of the coupling constant, that include as particular cases the most interesting of minimal and conformal coupling.Comment: 4 page

Lagged and instantaneous dynamical influences related to brain structural connectivity

Contemporary neuroimaging methods can shed light on the basis of human neural and cognitive specializations, with important implications for neuroscience and medicine. Different MRI acquisitions provide different brain networks at the macroscale; whilst diffusion-weighted MRI (dMRI) provides a structural connectivity (SC) coincident with the bundles of parallel fibers between brain areas, functional MRI (fMRI) accounts for the variations in the blood-oxygenation-level-dependent T2* signal, providing functional connectivity (FC).Understanding the precise relation between FC and SC, that is, between brain dynamics and structure, is still a challenge for neuroscience. To investigate this problem, we acquired data at rest and built the corresponding SC (with matrix elements corresponding to the fiber number between brain areas) to be compared with FC connectivity matrices obtained by 3 different methods: directed dependencies by an exploratory version of structural equation modeling (eSEM), linear correlations (C) and partial correlations (PC). We also considered the possibility of using lagged correlations in time series; so, we compared a lagged version of eSEM and Granger causality (GC). Our results were two-fold: firstly, eSEM performance in correlating with SC was comparable to those obtained from C and PC, but eSEM (not C nor PC) provides information about directionality of the functional interactions. Second, interactions on a time scale much smaller than the sampling time, captured by instantaneous connectivity methods, are much more related to SC than slow directed influences captured by the lagged analysis. Indeed the performance in correlating with SC was much worse for GC and for the lagged version of eSEM. We expect these results to supply further insights to the interplay between SC and functional patterns, an important issue in the study of brain physiology and function.Comment: Accepted and published in Frontiers in Psychology in its current form. 27 pages, 1 table, 5 figures, 2 suppl. figure