Rational divisors in rational divisor classes

We discuss the situation where a curve C, defined over a number field K, has a known K-rational divisor class of degree 1, and consider whether this class contains an actual K-rational divisor. When C has points everywhere locally, the local to global principle of the Brauer group gives the existence of such a divisor. In this situation, we give an alternative, more down to earth, approach, which indicates how to compute this divisor in certain situations. We also discuss examples where C does not have points everywhere locally, and where no such K-rational divisor is contained in the K-rational divisor class

Short-term administration of isotretinoin elevates plasma triglyceride concentrations without affecting insulin sensitivity in healthy humans

Résumé: Les mécanismes responsables de la résistance à l'insuline associée à l'hypertriglycéridémie chez l'homme sont mal connus. Il a été proposé que l'hypertriglycéridémie n'engendrait une résistance à l'insuline que lorsqu'elle est associée à une augmentation du transfert de lipides dans le muscle. Selon cette hypothèse, une hypertriglycéridémie secondaire à la diminution de l'élimination de particules riches en triglycérides ne devrait pas engendrer de résistance à l'insuline. Afin de vérifier cette hypothèse, nous avons étudié la sensibilité à l'insuline (au niveau du corps entier et du tissu adipeux) chez 15 sujets volontaires masculins avant et après 5 jours d'un traitement par l'acide 13-cis rétinoïque (1 mg/kg/j), un dérivé de la vitamine A qui diminue l'élimination des particules riches en triglycérides. Au cours d'un clamp hyperinsulinémique euglycémique à 3 paliers, nous avons mesuré le métabolisme global du glucose dépendant de l'insuline (6,6 2 H2 glucose), l'oxydation du glucose (calorimétrie indirecte), la lipolyse (2 H5 glycérol) et la lipolyse du tissu adipeux sous-cutané (microdialyse). L'acide 13-cis rétinoïque a augmenté le taux plasmatique de triglycérides de 0.97 ±0.15 à 1.30 ± 0.22 mmol/l (p <0.02) mais n'a pas eu d'effet sur le métabolisme global du glucose et la lipolyse. Ces observations sont compatibles avec une diminution de l'élimination des particules riches en triglycérides induite par l'acide 13-cis rétinoïque. L'inhibition de la production endogène du glucose et la diminution du glycérol sous-çutané induites par l'insuline n'ont pas été affectées par l'administration d'acide 13-cis rétinoïque. Nous concluons que la diminution de l'élimination des particules riches en triglycérides induite par 5 jours d'acide 13-cis rétinoïque n'a pas d'influence sur les mécanismes antilipolytiques ou sur le métabolisme du glucose dépendant de l'insuline. Ces résultats soutiennent le concept que la résistance à l'insuline associée à l'hypertriglycéridémie se développe principalement quand la production de triglycérides est augmentée. Abstact: The mechanism underlying hypertriglyceridemia-associated insulin resistance in humans remains poorly understood. It has been proposed that hypertriglyceridemia only produces insulin resistance when associated with an increased lipid delivery to muscle. Accordingly, hypertriglyceridemia secondary to a decreased clearance of triglyceride-rich particles should not cause insulin resistance. To verify this hypothesis, we assessed whole body and adipose tissue insulin sensitivity in 15 healthy male volunteers before and after a 5-day administration of isotretinoin (1 mg/kg/d), a vitamin A derivative that decreases the clearance of triglyceride-rich particles. Whole body insulin-mediated glucose disposal (6,6 2 H2glucose), glucose oxidation (indirect calorimetry), lipolysis (2H5 glycerol), and subcutaneous adipose lipolysis (microdialysis) were evaluated during a 3-step hyperinsulinemic euglycemic clamp. Isotretinoin increased plasma triglyceride from 0.97 ± 0.15 to 1.30 ± 0.22 mmol/L (P < .02), but did not change whole body insulin-mediated glucose disposal and lipolysis. These observations are consistent with an isotretinoin-induced inhibition of very-low-density lipoprotein (VLDL)-triglyceride clearance. The suppression of endogenous glucose production and the reduction in subcutaneous adipose glycerol concentrations by insulin remained equally unaffected after isotretinoin administration. We conclude that the impaired clearance of triglyceride-rich particles secondary to a 5-day isotretinoin administration does not impair insulin-mediated antilipolysis or glucose disposal. The data support the concept that hypertriglyceridemia-associated insulin resistance develops primarily when triglyceride production is increased

Programmed Instruction from the Instructor\u27s Viewpoint

The role of the instructor is, and always will be, a critical one. Until now, though, mediating a course to a self-paced, programmed learning environment frequently has neglected the fact that the instructor will have to alter teaching methods to a great extent in order to cope with the new situation. Further, without a thorough understanding of the role to be played out, the instructor could actually destroy even the best of courses. This report studies the changeover of United States Air Force technical training course 3ABR25130 Weather Specialist from group-lock step to self-paced programmed learning. A background of both military technical training and the specific course are given as well as a thorough discussion of attitudes expressed by instructors through the use of a seventy-three item open-ended questionnaire. The effort focuses on attitudes that curriculum designers and administrators must be cognizant of in order to design courses and materials that both student and instructors can live with

Programmed Instruction from the Instructor\u27s Viewpoint

The role of the instructor is, and always will be, a critical one. Until now, though, mediating a course to a self-paced, programmed learning environment frequently has neglected the fact that the instructor will have to alter teaching methods to a great extent in order to cope with the new situation. Further, without a thorough understanding of the role to be played out, the instructor could actually destroy even the best of courses. This report studies the changeover of United States Air Force technical training course 3ABR25130 Weather Specialist from group-lock step to self-paced programmed learning. A background of both military technical training and the specific course are given as well as a thorough discussion of attitudes expressed by instructors through the use of a seventy-three item open-ended questionnaire. The effort focuses on attitudes that curriculum designers and administrators must be cognizant of in order to design courses and materials that both student and instructors can live with

The Properties of the Heterogeneous Shakhbazyan Groups of Galaxies in the SDSS

We present a systematic study of the sub-sample of Shakhbazyan groups (SHKs) covered by the Sloan Digital Sky Survey Data Release--5 (SDSS-5). SHKs probe an environment with characteristics which are intermediate between those of loose and very compact groups. Surprisingly, we found that several groups identifying algorithms (e.g. Berlind et al. 2006, Tago et al. 2008) miss this type of structures. Using the SDSS-5 spectroscopic data and the photometric redshifts derived in D'Abrusco et al. 2007, we identified possible group members in photometric redshift space and derived, for each group, several individual properties. We also combined pointed and stacked Rosat All Sky Survey data to investigate the X-ray luminosities of these systems. Our study confirms that the majority of groups are physical entities with richness in the range 3--13 galaxies, and properties ranging between those of loose and compact groups. We confirm that SHK groups are richer in early-type galaxies than the surrounding environment and the field, as expected from the morphology-density relation and from the selection of groups of red galaxies. Furthermore, our work supports the existence of two sub-classes of structures, the first one being formed by compact and isolated groups and the second formed by extended structures. We suggest that while the first class of objects dwells in less dense regions like the outer parts of clusters or the field, possibly sharing the properties of Hickson Compact Groups, the more extended structures represent a mixture of [core+halo] configurations and cores of rich clusters. X-ray luminosities for SHKs are generally consistent with these results and with the expectations for the L_X-sigma_v relation, but also suggest the velocity dispersions reported in literature are underestimated for some of the richest systems.Comment: 20 pages, 14 figures, 4 tables. Accepted for publication by MNRA

Properties of short-range and long-range correlation energy density functionals from electron-electron coalescence

The combination of density functional theory with other approaches to the many-electron problem through the separation of the electron-electron interaction into a short-range and a long-range contribution is a promising method, which is raising more and more interest in recent years. In this work some properties of the corresponding correlation energy functionals are derived by studying the electron-electron coalescence condition for a modified (long-range-only) interaction. A general relation for the on-top (zero electron-electron distance) pair density is derived, and its usefulness is discussed with some examples. For the special case of the uniform electron gas, a simple parameterization of the on-top pair density for a long-range only interaction is presented and supported by calculations within the ``extended Overhauser model''. The results of this work can be used to build self-interaction corrected short-range correlation energy functionals.Comment: revised version, to appear in Phys. Rev.

Local-spin-density functional for multideterminant density functional theory

Based on exact limits and quantum Monte Carlo simulations, we obtain, at any density and spin polarization, an accurate estimate for the energy of a modified homogeneous electron gas where electrons repel each other only with a long-range coulombic tail. This allows us to construct an analytic local-spin-density exchange-correlation functional appropriate to new, multideterminantal versions of the density functional theory, where quantum chemistry and approximate exchange-correlation functionals are combined to optimally describe both long- and short-range electron correlations.Comment: revised version, ti appear in PR

SLICC/ACR DAMAGE INDEX IS VALID, AND RENAL AND PULMONARY ORGAN SCORES ARE PREDICTORS OF SEVERE OUTCOME IN PATIENTS WITH SYSTEMIC LUPUS ERYTHEMATOSUS

We investigated the Systemic Lupus International Collaborative Clinics/American College of Rheumatology (SLICC/ACR) Damage Index as a predictor of severe outcome and an indicator of morbidity in different ethnic groups, and in regard to its validity. We retrospectively studied disease course within 10 yr of diagnosis in an inception cohort of 80 patients with systemic lupus erythematosus (SLE). The mean renal damage score (DS) at 1 yr after diagnosis was a significant predictor of endstage renal failure and the mean pulmonary DS at 1 yr significantly predicted death within 10 yr of diagnosis. Compared to Caucasians, Afro-Caribbeans and Asians had significantly higher mean total DS at 5 and 10 yr, and higher mean renal DS at 10 yr. At 5 yr, the mean renal DS in Afro-Caribbeans and the mean neuropsychiatric DS in Asians were significantly higher than in Caucasians. The rate of endstage renal failure in Caucasians was significantly lower than in the other ethnic groups. Our results confirm the validity of the SLICC/ACR Damage Inde