The Fate of the First Galaxies. I. Self-Consistent Cosmological Simulations with Radiative Transfer

In cold dark matter (CDM) cosmogonies, low-mass objects play an important role in the evolution of the universe. Not only are they the first luminous objects to shed light in a previously dark universe, but, if their formation is not inhibited by their own feedback, they dominate the galaxy mass function until redshift z \sim 5. In this paper we present and discuss the implementation of a 3D cosmological code that includes most of the needed physics to simulate the formation and evolution of the first galaxies with a self-consistent treatment of radiative feedback. The simulation includes continuum radiative transfer using the ``Optically Thin Variable Eddington Tensor'' (OTVET) approximation and line-radiative transfer in the H_2 Lyman-Werner bands of the background radiation. We include detailed chemistry for H_2 formation/destruction, molecular and atomic cooling/heating processes, ionization by secondary electrons, and heating by Ly\alpha resonant scattering. We find that the first galaxies ("small-halos") are characterized by a bursting star formation, self-regulated by a feedback process that acts on cosmological scales. Their formation is not suppressed by feedback processes; therefore, their impact on cosmic evolution cannot be neglected. The main focus of this paper is on the methodology of the simulations, and we only briefly introduce some of the results. An extensive discussion of the results and the nature of the feedback mechanism are the focus of a companion paper.Comment: Accepted for publication on ApJ, 33 pages, including 14 figures and 2 tables. Movies and a higher quality version of the paper (figures) are available at: http://casa.colorado.edu/~ricotti/MOVIES.htm

The sutures in dentistry

In oral surgery, the last phase of a surgical operation is represented by the tissues suture, that allows the wound lips edges approximation and their stabilization, to promote haemostasis, to avoid the alimentary residues accumulation on the incision line and allow the first intention healing. A good suture avoids that the displacing forces generated by the muscular insertions, functional movements and by the external agents destabilize or cause the surgical wound deiscence. The purpose of this study was to re-examine the suture threads characteristics, properties and biological interactions evaluating the different studies published in literature results and conclusions. In conclusion, the authors recommended the use of the different suture threads on the dependence of the oral surgery operation type that must be performed, of the patient compliance and of the various suture materials physical and biocompatibility characteristics

A demonstrator for bolometric interferometry

Bolometric Interferometry (BI) is one of the most promising techniques for precise measurements of the Cosmic Microwave Background polarization. In this paper, we present the results of DIBO (Demonstrateur d'Interferometrie Bolometrique), a single-baseline demonstrator operating at 90 GHz, built to proof the validity of the BI concept applied to a millimeter-wave interferometer. This instrument has been characterized in the laboratory with a detector at room temperature and with a 4 K bolometer. This allowed us to measure interference patterns in a clean way, both (1) rotating the source and (2) varying with time the phase shift among the two interferometer's arms. Detailed modelisation has also been performed and validated with measurements.Comment: 15 pages, 14 figure

Clinical, epidemiological and virological features of acute hepatitis B in Italy

Purpose To evaluate the association of hepatitis B virus (HBV) genotypes, basal core promoter (BCP)/precore (PC) and S gene mutations with the clinical-epidemiological characteristics of acute hepatitis B (AHB) in Italy. Methods During July 2005–January 2007, 103 symptomatic AHB patients were enrolled and prospectively followed up at 15 national hospitals. HBV genotypes, BCP/ PC and S gene variants were determined by nested-PCR and direct sequence analysis. Results Genotype D, A and F were detected in 49, 45 and 6 % of patients, respectively. BCP, PC, and BCP plus PC variants were found in 3.1, 11.3 and 7.2 % of patients, respectively. At enrollment, 68.3 % of patients were hepatitis B e antigen (HBeAg)-positive and 31.7 % HBeAg-negative. BCP/PC mutations were more common in HBeAg-negative than in HBeAg-positive patients (p < 0.0001). Compared to genotype D patients, those harboring non-D genotypes were more frequently males (p = 0.023), HBeAg-positive (p < 0.001), had higher bilirubin (p = 0.014) and viremia (p = 0.034) levels and less frequently carried BCP/PC mutations (p < 0.001). Non-D genotype patients more often were from Central Italy (p = 0.001) and reported risky sexual exposure (p = 0.021). Two patients had received vaccination before AHB: one harbored genotype F; the other showed a S gene mutation. Four patients developed fulminant AHB; mutations were found in 2 of 3 patients who underwent BCP/ PC sequencing. After a 6-month follow-up, only 2 (2.8 %) patients developed persistent infection. Conclusion AHB by non-D genotypes is increasing in Italy and is associated with risky sexual exposure. The ability of some genotypes to cause persistent and/or severe infection in Italy warrants larger studies for clarificatio

Tectosedimentary evolution of the Payogastilla Group and and its relation to Cenozoic volcanic arc, in the Calchaquí, Tonco and Amblayo valleys, Salta province, Argentina

Las características estratigráficas y sedimentológicas de los depósitos del Grupo Payogastilla son aspectos muy importantes a tener en cuenta para investigar la evolución tecto-sedimentaria de la cuenca de antepaís andino en el noroeste de la Argentina. El límite estratigráfico inferior del Grupo Payogastilla está marcado por una paraconcordancia con los depósitos de post-rift de la Formación Lumbrera (Subgrupo Santa Bárbara, Grupo Salta). El límite estratigrá- fico superior de la Formación Los Colorados, es paraconcordante y discordante; la subsidencia de la cuenca fue pareja entre ~35 a 21 Ma. En el Mioceno medio a superior, los depósitos de la Formación Angastaco, con espesores de 4550 m (río Calchaquí) y 1500 m (Tonco) reflejan una importante influencia tectónica, la que delimitó el depocentro de la cuenca de Angastaco, con un inicio en el valle El Tonco (>13,7 Ma) y posteriormente en el valle Calchaquí (~13 Ma). Con posterioridad a los ~13 Ma se habrían desarrollado incipientes barreras orográficas en el este (sierras Los Colorados y León Muerto), que durante el Mioceno superior (10 a 5 Ma) se habrían reactivado para formar cadenas orográficas importantes. Durante el Plioceno se habrían reactivado nuevamente los alzamientos tectónicos, generando sistemas fluviales entrelazados gravosos, con una marcada proveniencia desde el este. Los niveles de tobas intercalados en los depósitos de las formaciones Angastaco y Palo Pintado, muestran una clara signatura de arco indicando su proveniencia del arco activo a esos tiempos, con características que indican una componente cortical participante en sus magmas. Mientras que, los niveles piroclásticos intercalados en la Formación San Felipe, por su mayor carácter peraluminoso y sus menores contenidos en Na20 respecto a K20, que las ubican en el campo de los granitos tipo S, dando idea de componentes corticales distintas.The stratigraphic and sedimentological characteristics of Payogastilla Group deposits are very important to study tecto-sedimentary evolution of the Andean foreland basin in northwestern Argentina. The lower stratigraphic boundary of Payogastilla Group with the Lumbrera Formation (Santa Barbara Subgroup, Salta Group) deposits is a paraconformity. The upper stratigraphic boundary, the Colorados Formations is a paraconformity and a unconformity, the subsidence of the basin was uniform and the duration of the initial deposit was about ~35 to 21 Ma. During the middle to upper Miocene, represented by Angastaco Formation deposits, with a thickness of 4550 m (in Calchaquí river) and 1500 m (in Tonco) it took place a major tectonic influence, which delimited the basin depocenter in Angastaco basin. This event started in Tonco valley (>13.7 Ma) and later continued in Calchaquí valley (~13 Ma). Also in the ~13 Ma it have developed two orographic barriers (Los Colorados and León Muerto ranges), in the eastern, that during the Late Miocene (10-5 Ma) would have been reactivated to an important orographic chains form. During the Pliocene the tectonic uplifts would have reactivated, being registered as alluvial fans with a strong provenance from the east. Levels tuff deposits intercalated in Angastaco and Palo Pintado formations, show a clear signature of the arc indicating their origin of the arc active to those times with features that indicate a crustal component in their magmas participant. While pyroclastic levels intercalated in San Felipe Formation, with higher peraluminous character and lower Na20 K20 content regarding, which lie in the area of the type S granites, giving different cortical components idea.Fil: Galli, Claudia. Universidad Nacional de Salta; ArgentinaFil: Coira, Beatriz Lidia Luisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta; ArgentinaFil: Alonso, Ricardo Narciso. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta; Argentina. Universidad Nacional de Salta; ArgentinaFil: Matteini, Massimo. Universidade Do Brasilia; BrasilFil: Hauser, Natalia. Universidade Do Brasilia; Brasi

The effects of surgical preparation techniques and implant macro-geometry on primary stability : an in vitro study

The attainment of a good primary stability is a necessary condition to ensure the success of osseointegration in implantology. In type IV cancellous bone, however, it is possible that a reduced primary stability can lead to an increased rate of failure. The aim of this study was therefore to determine, with the help of the resonance frequency (Osstell mentor), which technique of implant site preparation (piezo surgery, conventional, under-preparation, bone compaction, osteodistraction) and macro-geometry is able to improve implant stability in type IV cancellous bone. 10 pig ribs were prepared with a surgical pre-drilled guide, calibrated for a correct implant positioning. On each rib, 5 implant sites (one for each technique) were prepared. Successively, 50 conical implants (Tekka Global D) were inserted and measured with the resonance frequency to evaluate the primary stability. Data collected were analyzed by analysis of variance (ANOVA) to test whether the Implant Stability Quotient (ISQ) values of the five techniques were significantly different. The results showed that no significant differences among the ISQ values of the five techniques used were found. Also, no significant differences in the macro-geometry of the two types of compared implants were observed. However, the macro-geometry of Tekka implants, characterized by a double condensing thread, seems to provide greater ISQ values than those of single thread implants when using the same technique. In light of these preliminary data, it is conceivable that in cases of reduced stability, such as those occurring with a type IV bone, all means ameliorating the primary stability and accelerating the osseointegration can be utilized

Phylogeographical and evolutionary history of variola major virus; a question of timescales?

Aim of this study was to reconstruct the phylogeography of variola virus (VARV) in the XX century, using 47 VARV whole genome sequences available in public databases, through two different methods for ancestral character reconstruction: a frequently used Bayesian framework and a fast maximum-likelihood (ML) based method. The substitution rate of the whole VARV genome was estimated to be between 6.7×10-6 and 1.1×10-5 substitutions/site/year. Both ML and Bayesian methods gave similar trees topology, showing two distinct monophyletic groups: one (known as P1) including the great part of variola major and the second (P2) including West African and American (variola minor) isolates and close evolutionary rate estimations, between 6.73×10-6 and 1.1×10-5 for the whole genome. The phylogeographical reconstruction of P1 suggested that the common ancestor of the variola major circulating in the Old World between the 1940s and the 1970s most probably originated in the Far East in the first decades of the XX century, and then spread to Indian subcontinent in the 1920s. India represented a center of further spread of VARV to eastern Africa in the 1940s and to the Middle East in the 1960s. The phylogeographic scenario obtained by the maximum-likelihood based method was congruent with that obtained by Bayesian framework, but the analysis was faster indicating the usefulness of this method in the analyses of large viral genomes. Our results may help to explain the controversial reconstructions of the history of VARV obtained using long or short timescale for calibration