The Evolution of the Lyman-Alpha Luminosity Function During Reionization

The time frame in which hydrogen reionization occurred is highly uncertain, but can be constrained by observations of Lyman-alpha (Ly$\alpha$) emission from distant sources. Neutral hydrogen in the intergalactic medium (IGM) attenuates Ly$\alpha$~photons emitted by galaxies. As reionization progressed the IGM opacity decreased, increasing Ly$\alpha$~visibility. The galaxy Ly$\alpha$~luminosity function (LF) is thus a useful tool to constrain the timeline of reionization. In this work, we model the Ly$\alpha$~LF as a function of redshift, $z=5-10$, and average IGM neutral hydrogen fraction, \overline{x}_\textsc{hi}. We combine the Ly$\alpha$~luminosity probability distribution obtained from inhomogeneous reionization simulations with a model for the UV LF to model the Ly$\alpha$~LF. As the neutral fraction increases, the average number density of Ly$\alpha$~emitting galaxies decreases, and are less luminous, though for \overline{x}_\textsc{hi} \lesssim 0.4 there is only a small decrease of the Ly$\alpha$~LF. We use our model to infer the IGM neutral fraction at $z=6.6, 7.0, 7.3$ from observed Ly$\alpha$~LFs. We conclude that there is a significant increase in the neutral fraction with increasing redshift: \overline{x}_\textsc{hi}(z=6.6)=0.08^{+ 0.08}_{- 0.05}, \, \overline{x}_\textsc{hi}(z=7.0)=0.28 \pm 0.05 and \overline{x}_\textsc{hi}(z=7.3)=0.83^{+ 0.06}_{- 0.07}. We predict trends in the Ly$\alpha$~luminosity density and Schechter parameters as a function of redshift and the neutral fraction. We find that the Ly$\alpha$~luminosity density decreases as the universe becomes more neutral. Furthermore, as the neutral fraction increases, the faint-end slope of the Ly$\alpha$~LF steepens, and the characteristic Ly$\alpha$~luminosity shifts to lower values, concluding that the evolving shape of the Ly$\alpha$~LF -- not just its integral -- is an important tool to study reionization.Comment: 20 pages, 10 figures, submitted to Ap

Does mild COPD affect prognosis in the elderly?

<p>Abstract</p> <p>Background</p> <p>Chronic obstructive pulmonary disease (COPD) affects independence and survival in the general population, but it is unknown to which extent this conclusion applies to elderly people with mild disease. The aim of this study was to verify whether mild COPD, defined according to different classification systems (ATS/ERS, BTS, GOLD) impacts independence and survival in elderly (aged 65 to 74 years) or very elderly (aged 75 years or older) patients.</p> <p>Methods</p> <p>We used data coming from the Respiratory Health in the Elderly (Salute Respiratoria nell'Anziano, SaRA) study and compared the differences between the classification systems with regards to personal capabilities and 5-years survival, focusing on the mild stage of COPD.</p> <p>Results</p> <p>We analyzed data from 1,159 patients (49% women) with a mean age of 73.2 years (SD: 6.1). One third of participants were 75 years or older. Mild COPD, whichever was its definition, was not associated with worse personal capabilities or increased mortality after adjustment for potential confounders in both age groups.</p> <p>Conclusions</p> <p>Mild COPD may not affect survival or personal independence of patients over 65 years of age if the reference group consists of patients with a comparable burden of non respiratory diseases. Comorbidity and age itself likely are main determinants of both outcomes.</p

Treatment of human brucellosis with rifampin plus minocycline

In order to evaluate the efficacy and tolerability of a high intravenous dose of rifampin plus oral minocycline (administered daily for 3 weeks) for the treatment of acute brucellosis, we retrospectively reviewed the outcome of 239 consecutive patients (135 adults and 104 children) diagnosed and treated over a 17-year period in Italy. The combination used resulted in 100% response and a relapse rate lower than 2%. Fifty-two (30 adults and 22 children) (29.8%) complained of mild adverse effects including an increase in aspartate aminotransferase (>250 IU) observed in 12 cases and considered related to rifampin and in 11 cases a reversible hyperpigmentation of the tongue attributed to minocycline. A randomized prospective comparative study should be performed to confirm our encouraging result

The Evolution of the Lyman-alpha Luminosity Function during Reionization

The time frame in which hydrogen reionization occurred is highly uncertain, but can be constrained by observations of Lyman-alpha (Lya) emission from distant sources. Neutral hydrogen in the intergalactic medium (IGM) attenuates Lya photons emitted by galaxies. As reionization progressed the IGM opacity decreased, increasing Lya visibility. The galaxy Lya luminosity function (LF) is thus a useful tool to constrain the timeline of reionization. In this work, we model the Lya LF as a function of redshift, z = 5 10, and average IGM neutral hydrogen fraction, xH?. We combine the Lya luminosity probability distribution obtained from inhomogeneous reionization simulations with a model for the UV LF to model the Lya LF. As the neutral fraction increases, the average number density of Lya emitting galaxies decreases, and are less luminous, though for xH? ? 0.4 there is only a small decrease in the Lya LF. We use our model to infer the IGM neutral fraction at z = 6.6, 7.0, and 7.3 from observed Lya LFs. We conclude that there is a significant increase in the neutral fraction with increasing redshift: = = - = = ? x z 6.6 0.08+ , x z 7.0 0.28 0.05 H 0.05 0.08 ? ( ) H? ( ) and = = - x z 7.3 0.83+ H 0.07 0.06 ? ( ) . We predict trends in the Lya luminosity density and Schechter parameters as a function of redshift and the neutral fraction. We find that the Lya luminosity density decreases as the universe becomes more neutral. Furthermore, as the neutral fraction increases, the faint-end slope of the Lya LF steepens, and the characteristic Lya luminosity shifts to lower values; hence, we conclude that the evolving shape of the Lya LF not just its integral is an important tool to study reionization

Human toxocariasis: a report of nine cases

Aim: Human toxocariasis is caused by infection with the larval stage of nematode parasites of dogs and cats, Toxocara canis or Toxocara cati. These helminths are not able to complete their life cycle in undefinitive hosts and so undergo aberrant migrations in the tissues causing a wide spectrum of signs and symptoms. Eosinophilia is often severe and sometimes represents the only sign of infection, except in ocular and neurological forms. Methods: We describe the clinical features of nine children affected by toxocariasis admitted to our Infectious Diseases department from 2004 to 2006. Results: Fever and hepatomegaly were the most common clinical findings. In two cases eosinophilia was not present. Diagnosis was performed by enzyme-linked immunosorbent assay employing excretory–secretory antigens of Toxocara. canis larvae. All patients were successfully treated with oral albendazole with no side effects

The Impact of Cosmic Variance on Inferences of Global Neutral Fraction Derived from Lyα\alpha Luminosity Functions During Reionization

We investigate the impact of field-to-field variation, deriving from cosmic variance, in measured Lyman-$\alpha$ emitter (LAE) luminosity functions (LFs) and this variation's impact on inferences of the neutral fraction of the intergalactic medium (IGM) during reionization. We post-process a z=7 IGM simulation to populate the dark matter halos with LAEs. These LAEs have realistic UV magnitudes, Ly$\alpha$ fluxes, and Ly$\alpha$ line profiles. We calculate the attenuation of Ly$\alpha$ emission in universes with varying IGM neutral fraction, $\bar{\rm{x}}_{\rm{HI}}$. In a $\bar{\rm{x}}_{\rm{HI}}=0.3$ simulation, we perform 100 realizations of a mock 2 square degree survey with a redshift window $\Delta z = 0.5$ and flux limit $\rm{f}_{Ly\alpha}>1\times10^{-17}\:\rm{ergs}\:\: \rm{s}^{-1} \: \rm{cm}^{-2}$; such a survey is typical in depth and volume of the largest LAE surveys conducted today. For each realization, we compute the LAE LF and use it to recover the input $\bar{\rm{x}}_{\rm{HI}}$. Comparing the inferred values of $\bar{\rm{x}}_{\rm{HI}}$ across the ensemble of the surveys, we find that cosmic variance, deriving from large-scale structure and variation in the neutral gas along the sightline, imposes a floor in the uncertainty of $\Delta \bar{\rm{x}}_{\rm{HI}} \sim 0.2$ when $\bar{\rm{x}}_{\rm{HI}}$ $=0.3$. We explore mitigation strategies to decrease this uncertainty, such as increasing the volume, decreasing the flux limit, or probing the volume with many independent fields. Increasing the area and/or depth of the survey does not mitigate the uncertainty, but composing a survey with many independent fields is effective. This finding highlights the best strategy for LAE surveys aiming at constraining $\bar{\rm{x}}_{\rm{HI}}$ of the universe during reionization.Comment: 17 pages, 13 figure

Visceral leishmaniasis, hypertriglyceridemia and secondary hemophagocytic lymphohistiocytosis

Visceral leishmaniasis (VL), a protozoan disease, is 100 % fatal if left untreated. Anemia is common in VL which plays a role in expression of clinically overt VL disease. Laboratory clues are scarce for strengthening clinical suspicion for severity in VL. Hypertriglyceridemia has emerged as a new concept for the diagnosis and prognosis in VL. The present study is aimed at correlating the magnitude of hypertriglyceridemia with the severity in VL. Materials and methods: A retrospective case–control study was conducted between January 2012 to December 2013 among 124 patients coming for treatment from VL endemic areas, who had fever of more than 15 days and did not respond to antimalarials and antibiotics. The parasitologically confirmed VL cases (n = 87) were categorized as mild/moderate (n = 60) and severe (n = 27) groups according to WHO classification for anemia and parasite burden. Serum triglycerides were assayed in VL groups along with controls (n = 37). Results: Serum triglyceride level was significantly higher in VL than controls [mean values were 173.50 ± 47.67 versus 127.1 ± 53.79 mg/dl, respectively (p 161.7 mg/dl) was noted in all severe VL patients, compared to 31.66 % of mild or moderate group (p < 0.0001). There was no significant difference between mild/moderate VL and controls. Conclusions: It is hypothesized that hypertriglyceridemia could be of additional diagnostic benefit to assess the probability and severity of VL in endemic areas. © 2015, Springer-Verlag Berlin Heidelberg

Fourth case of louse-borne relapsing fever in Young Migrant, Sicily, Italy, December 2015. Mini Review Article

Objectives Currently louse-borne relapsing fever (LBRF) is primarily found in limited endemic foci in Ethiopia, Somalia and Sudan; no case of imported LBRF has been reported in Europe in the 9 years prior to 2015. The aim of our paper is to describe a new case of imported LBRF detected in Sicily, Italy, and to review all cases reported in migrants arrived in Europe in the last 10 years. Study design Mini review of all published cases of louse-borne relapsing fever in Europe in the last 10 years. Methods A computerized search without language restriction was conducted using PubMed combining the terms ‘(louse-borne relapsing fever or LBRF or recurrentis) and (refugee or Europe or migrant)’ without limits. Furthermore, the ‘Ahead-of-Print Articles’ of the top 10 journals (ranked by Impact factor – Web of Science) of Infectious diseases and of Epidemiology were checked. Results Our search identified 26 cases of LBRF between July and October 2015 in migrants recently arrived in Europe: 8 had been described in Italy; 1 in Switzerland; 2 in the Netherlands; 15 in Germany. We describe data regarding the clinical characteristics, diagnostic methods, therapy and outcome of these patients and of the new case. Conclusions LBRF by Borrelia recurrentis should be considered among the clinical hypotheses in migrants presenting with fever, headache, chills, sweating, arthralgia, myalgia, dizziness, nausea and vomiting

A case of Brucella endocarditis in association with subclavian artery thrombosis

Brucellosis is a common zoonosis, endemic in Mediterranean countries, and caused by bacteria of Brucella genus. Brucellosis is a systemic infection and the clinical presentation varies widely from asymptomatic and mild to severe disease. Cardiovascular complications are extremely rare. We present a case of arterial thrombosis in a previously healthy young patient with Brucella endocarditis. Careful attention must be paid to any sign or symptom of thrombosis in patients affected by brucellosis, regardless of the presence of endocarditis and cardiovascular risk factors. PMID:22844622[PubMed] PMCID:PMC3400327Free PMC Articl