The Positive Feedback of Pop III Objects on Galaxy Formation

We study the formation of molecular hydrogen in cooling gas behind shocks produced during the blow-away process thought to occur in the first collapsed, luminous (Pop III) objects in the early universe. We find that for a wide range of physical parameters the $H_2$ fraction is $f \approx 6 \times 10^{-3}$. The $H_2$ mass produced in such explosions can exceed the amount of relic $H_2$ destroyed inside the photodissociation region surrounding a given Pop III. We conclude that these first objects, differently from the suggestion of Haiman et al 1997, might have a net positive feedback on subsequent galactic formation. We discuss the effects of radiation and the implications of our results for the soft-UV background.Comment: 16 pages, aasms4.sty, LaTeX, 2 figures. submitted to ApJ Letter

The O VI Absorbers Toward PG0953+415: High Metallicity, Cosmic-Web Gas Far From Luminous Galaxies

The spectrum of the low-redshift QSO PG0953+415 shows two strong, intervening O VI absorption systems. To study the nature of these absorbers, we have used the Gemini Multiobject Spectrograph to conduct a deep spectroscopic galaxy redshift survey in the 5' x 5' field centered on the QSO. This survey is fully complete for r' < 19.7 and is 73% complete for r' < 21.0. We find three galaxies at the redshift of the higher-z O VI system (z = 0.14232) including a galaxy at projected distance rho = 155 kpc. We find no galaxies in the Gemini field at the redshift of the lower-z O VI absorber (z = 0.06807), which indicates that the nearest galaxy is more than 195 kpc away or has L < 0.04 L*. Previous shallower surveys covering a larger field have shown that the z = 0.06807 O VI absorber is affiliated with a group/filament of galaxies, but the nearest known galaxy has rho = 736 kpc. The z = 0.06807 absorber is notable for several reasons. The absorption profiles reveal simple kinematics indicative of quiescent material. The H I line widths and good alignment of the H I and metal lines favor photoionization and, moreover, the column density ratios imply a high metallicity: [M/H] = -0.3 +/- 0.12. The z = 0.14232 O VI system is more complex and less constrained but also indicates a relatively high metallicity. Using galaxy redshifts from SDSS, we show that both of the PG0953+415 O VI absorbers are located in large-scale filaments of the cosmic web. Evidently, some regions of the web filaments are highly metal enriched. We discuss the origin of the high-metallicity gas and suggest that the enrichment might have occurred long ago (at high z).Comment: Submitted for publication in the Astrophysical Journal Letters. Figs. 1 and 2 compressed for astro-ph. High-resolution version available at http://www.astro.umass.edu/~tripp/astro/qualitypreps/pg0953tripp.pd

Surprisingly Little O VI Emission Arises in the Local Bubble

This paper reports the first study of the O VI resonance line emission (1032, 1038 Angstroms) originating in the Local Bubble (or Local Hot Bubble) surrounding the solar neighborhood. In spite of the fact that O VI absorption within the Local Bubble has been observed, no resonance line emission was detected during our 230 ksec Far Ultraviolet Spectroscopic Explorer observation toward a ``shadowing'' filament in the southern Galactic hemisphere. As a result, tight 2 sigma upper limits are set on the intensities in the 1032 and 1038 Angstrom emission lines: 500 and 530 photons cm^{-2} s^{-1} sr^{-1}, respectively. These values place strict constraints on models and simulations. They suggest that the O VI-bearing plasma and the X-ray emissive plasma reside in distinct regions of the Local Bubble and are not mixed in a single plasma, whether in equilibrium with T ~ 10^6 K or highly overionized with T ~ 4 to 6 x 10^4 K. If the line of sight intersects multiple cool clouds within the Local Bubble, then the results also suggest that hot/cool transition zones differ from those in current simulations. With these intensity upper limits, we establish limits on the electron density, thermal pressure, pathlength, and cooling timescale of the O VI-bearing plasma in the Local Bubble. Furthermore, the intensity of O VI resonance line doublet photons originating in the Galactic thick disk and halo is determined (3500 to 4300 photons cm^{-2} s^{-1} sr^{-1}), and the electron density, thermal pressure, pathlength, and cooling timescale of its O VI-bearing plasma are calculated. The pressure in the Galactic halo's O VI-bearing plasma (3100 to 3800 K cm^{-3}) agrees with model predictions for the total pressure in the thick disk/lower halo. We also report the results of searches for other emission lines.Comment: accepted by ApJ, scheduled for May 2003, replacement astro-ph submission corrects typos and grammatical errors in original versio

Low-temperature photocarrier dynamics in monolayer MoS2

The band structure of MoS$_2$ strongly depends on the number of layers, and a transition from indirect to direct-gap semiconductor has been observed recently for a single layer of MoS$_2$. Single-layer MoS$_2$ therefore becomes an efficient emitter of photoluminescence even at room temperature. Here, we report on scanning Raman and on temperature-dependent, as well as time-resolved photoluminescence measurements on single-layer MoS$_2$ flakes prepared by exfoliation. We observe the emergence of two distinct photoluminescence peaks at low temperatures. The photocarrier recombination at low temperatures occurs on the few-picosecond timescale, but with increasing temperatures, a biexponential photoluminescence decay with a longer-lived component is observed.Comment: 3 pages, 4 figure

Quality Of Life And Epilepsy Surgery In Childhood And Adolescence.

Epilepsy can affect the quality of life (QOL) of patients. The temporal lobe epilepsy (TLE) is often refractory to medication, which has an adverse impact on QOL. The surgery can be a form to control the seizures and to improve the QOL of the patients. The aim of this study was to verify the QOL of children and adolescents with TLE who underwent surgery for epilepsy, comparing QOL before and after surgery and investigating which parameters showed improvement. We used semi-structured questionnaire in the pre-and post-surgery in 13 patients. The data were analyzed using the Wilcoxon test. The analysis showed that there was general improvement in the QOL postoperatively. There was improvement in general health issues, adverse effects of antiepileptic drugs and the relationship with parents. When properly indicated, epilepsy surgery improves quality of life of patients with TLE.6923-

Dor abdominal recorrente: quando suspeitar de crise epiléptica?

Recurrent episodes of abdominal pain are common in childhood. Among the diagnostic possibilities are migraine and abdominal epilepsy (AE). AE is an infrequent syndrome with paroxystic episodes of abdominal pain, awareness disturbance, EEG abnormalities and positive results with the introduction of antiepileptic drugs. We present one 6 year-old girl who had short episodes of abdominal pain since the age of 4. The pain was followed by cry, fear and occasionally secondary generalization. MRI showed tumor in the left temporal region. As a differential diagnosis, we report a 10 year-old boy who had long episodes of abdominal pain accompanied by blurring of vision, vertigo, gait ataxia, dysarthria, acroparesthesias and vomiting. He received the diagnosis of basilar migraine. In our opinion, AE is part of a large group (partial epilepsies) and does not require a special classification. Pediatric neurologists must be aware of these two entities that may cause abdominal pain.Episódios recorrentes de dor abdominal são freqüentes na infância e entre as causas neurológicas há migrânea e epilepsia abdominal (EA). EA é uma síndrome que consiste de episódios paroxísticos de dor abdominal associada à alteração de consciência, anormalidades eletrencefalográficas e boa resposta à terapia anticonvulsivante. Apresentamos uma menina de 6 anos que tinha desde os 4 anos episódios de curta duração de dor abdominal, seguidos por choro, medo e ocasional generalização secundária. A RM mostrou a presença de um tumor em região temporal esquerda. Como diagnóstico diferencial, apresentamos um menino de 10 anos que há 12 meses referia episódios de dor abdominal de longa duração acompanhados por turvação visual, vertigem, marcha atáxica, disartria, acroparestesia e vômito, recebendo posteriormente o diagnóstico de migrânia basilar. Em nossa opinião, EA faz parte de um grande grupo (epilepsias parciais) e não requer uma classificação especial. O neuropediatra deve estar alerta para essas duas entidades que podem cursar com dor abdominal.62863

The Heavy Element Enrichment of Lyman alpha Clouds in the Virgo Supercluster

Using high S/N STIS echelle spectra (FWHM=7 km/s) of 3C 273, we constrain the metallicities of two Lya clouds in the vicinity of the Virgo cluster. We detect C II, Si II, and Si III absorption lines in the Lya absorber at z = 0.00530. Previous observations with FUSE have revealed Ly beta - Ly theta lines at this redshift, thereby accurately constraining N(H I). We model the ionization of the gas and derive [C/H] = -1.2^{+0.3}_{-0.2}, [Si/C] = 0.2+/-0.1, and log n_{H} = -2.8+/-0.3. The model implies a small absorber thickness, ~70 pc, and thermal pressure p/k ~ 40 cm^{-3} K. It is most likely that the absorber is pressure confined by an external medium because gravitational confinement would require a very high ratio of dark matter to baryonic matter. Based on Milky Way sight lines in which carbon and silicon abundances have been reliably measured in the same interstellar cloud (including new measurements presented herein), we argue that the overabundance of Si relative to C is not due to dust depletion. Instead, this probably indicates that the gas has been predominately enriched by Type II supernovae. Such enrichment is most plausibly provided by an unbound galactic wind, given the absence of galaxies within a projected distance of 100 kpc and the presence of galaxies capable of driving a wind at larger distances. We also constrain the metallicity and physical conditions of the Virgo absorber at z = 0.00337 based on detections of O VI and H I and an upper limit on C IV. If this absorber is collisionally ionized, the O VI/C IV limit requires T > 10^{5.3} K. For either collisional ionization or photoionization, we find that [O/H] > -2.0 at z = 0.00337.Comment: Final Ap.J. versio

Risk-Adjusted Cancer Screening and Prevention (RiskAP): Complementing Screening for Early Disease Detection by a Learning Screening Based on Risk Factors

Breast cancer; Evidence-generating care; Risk-adjusted preventionCáncer de mama; Atención generadora de evidencia; Prevención ajustada al riesgoCàncer de mama; Atenció generadora d'evidències; Prevenció ajustada al riscBackground: Risk-adjusted cancer screening and prevention is a promising and continuously emerging option for improving cancer prevention. It is driven by increasing knowledge of risk factors and the ability to determine them for individual risk prediction. However, there is a knowledge gap between evidence of increased risk and evidence of the effectiveness and efficiency of clinical preventive interventions based on increased risk. This gap is, in particular, aggravated by the extensive availability of genetic risk factor diagnostics, since the question of appropriate preventive measures immediately arises when an increased risk is identified. However, collecting proof of effective preventive measures, ideally by prospective randomized preventive studies, typically requires very long periods of time, while the knowledge about an increased risk immediately creates a high demand for action. Summary: Therefore, we propose a risk-adjusted prevention concept that is based on the best current evidence making needed and appropriate preventive measures available, and which is constantly evaluated through outcome evaluation, and continuously improved based on these results. We further discuss the structural and procedural requirements as well as legal and socioeconomical aspects relevant for the implementation of this concept.The project was funded by the German Federal Ministry of Health (grant No. 2515FSB401 to Rita Schmutzler and Christiane Woopen) for supporting the international expert meetings, and a grant of the EU Horizon 2020 program, BRIDGES (grant No. 634935, PI Peter Devilee, WP5-PI Rita Schmutzler), for the compilation of the most recent findings of genetic risk prediction

Infrared Spectroscopy of Molecular Supernova Remnants

We present Infrared Space Observatory spectroscopy of sites in the supernova remnants W28, W44, and 3C391, where blast waves are impacting molecular clouds. Atomic fine-structure lines were detected from C, N, O, Si, P, and Fe. The S(3) and S(9) lines of H2 were detected for all three remnants. The observations require both shocks into gas with moderate (~ 100 /cm3) and high (~10,000 /cm3) pre-shock densities, with the moderate density shocks producing the ionic lines and the high density shock producing the molecular lines. No single shock model can account for all of the observed lines, even at the order of magnitude level. We find that the principal coolants of radiative supernova shocks in moderate-density gas are the far-infrared continuum from dust grains surviving the shock, followed by collisionally-excited [O I] 63.2 and [Si II] 34.8 micron lines. The principal coolant of the high-density shocks is collisionally-excited H2 rotational and ro-vibrational line emission. We systematically examine the ground-state fine structure of all cosmically abundant elements, to explain the presence or lack of all atomic fine lines in our spectra in terms of the atomic structure, interstellar abundances, and a moderate-density, partially-ionized plasma. The [P II] line at 60.6 microns is the first known astronomical detection. There is one bright unidentified line in our spectra, at 74.26 microns. The presence of bright [Si II] and [Fe II] lines requires partial destruction of the dust. The required gas-phase abundance of Fe suggests 15-30% of the Fe-bearing grains were destroyed. The infrared continuum brightness requires ~1 Msun of dust survives the shock, suggesting about 1/3 of the dust mass was destroyed, in agreement with the depletion estimate and with theoretical models for dust destruction.Comment: 40 pages; 10 figures; accepted by ApJ July 11, 200