Strong Clustering of Lyman Break Galaxies around Luminous Quasars at z~4

In the standard picture of structure formation, the first massive galaxies are expected to form at the highest peaks of the density field, which constitute the cores of massive proto-clusters. Luminous quasars (QSOs) at z~4 are the most strongly clustered population known, and should thus reside in massive dark matter halos surrounded by large overdensities of galaxies, implying a strong QSO-galaxy cross-correlation function. We observed six z~4 QSO fields with VLT/FORS exploiting a novel set of narrow band filters custom designed to select Lyman Break Galaxies (LBGs) in a thin redshift slice of Delta_z~0.3, mitigating the projection effects that have limited the sensitivity of previous searches for galaxies around z>~4 QSOs. We find that LBGs are strongly clustered around QSOs, and present the first measurement of the QSO-LBG cross-correlation function at z~4, on scales of 0.1<~R<~9 Mpc/h (comoving). Assuming a power law form for the cross-correlation function xi=(r/r0_QG)^gamma, we measure r0_QG=8.83^{+1.39}_{-1.51} Mpc/h for a fixed slope of gamma=2.0. This result is in agreement with the expected cross-correlation length deduced from measurements of the QSO and LBG auto-correlation function, and assuming a linear bias model. We also measure a strong auto-correlation of LBGs in our QSO fields finding r0_GG=21.59^{+1.72}_{-1.69} Mpc/h for a fixed slope of gamma=1.5, which is ~4 times larger than the LBG auto-correlation length in random fields, providing further evidence that QSOs reside in overdensities of LBGs. Our results qualitatively support a picture where luminous QSOs inhabit exceptionally massive (M_halo>10^12 M_sun) dark matter halos at z~4.Comment: 25 pages, 22 figures, submitted to the Ap

Clustering of Lyman-alpha Emitters Around Quasars at z∼4z\sim4

The strong observed clustering of $z>3.5$ quasars indicates they are hosted by massive ($M_{\rm{halo}}\gtrsim10^{12}\,h^{-1}\,\rm{M_{\odot}}$) dark matter halos. Assuming quasars and galaxies trace the same large-scale structures, this should also manifest as strong clustering of galaxies around quasars. Previous work on high-redshift quasar environments, mostly focused at $z>5$, have failed to find convincing evidence for these overdensities. Here we conduct a survey for Lyman alpha emitters (LAEs) in the environs of 17 quasars at $z\sim4$ probing scales of $R\lesssim7\,h^{-1}\,{\rm{Mpc}}$. We measure an average LAE overdensity around quasars of 1.4 for our full sample, which we quantify by fitting the quasar-LAE cross-correlation function. We find consistency with a power-law shape with correlation length of $r^{QG}_{0}=2.78^{+1.16}_{-1.05}\,h^{-1}\,{\rm{cMpc}}$ for a fixed slope of $\gamma=1.8$. We also measure the LAE auto-correlation length and find $r^{GG}_{0}=9.12^{+1.32}_{-1.31}\,h^{-1}$\,cMpc ($\gamma=1.8$), which is $3.3$ times higher than the value measured in blank fields. Taken together our results clearly indicate that LAEs are significantly clustered around $z\sim4$ quasars. We compare the observed clustering with the expectation from a deterministic bias model, whereby LAEs and quasars probe the same underlying dark matter overdensities, and find that our measurements fall short of the predicted overdensities by a factor of 2.1. We discuss possible explanations for this discrepancy including large-scale quenching or the presence of excess dust in galaxies near quasars. Finally, the large cosmic variance from field-to-field observed in our sample (10/17 fields are actually underdense) cautions one from over-interpreting studies of $z\sim6$ quasar environments based on a single or handful of quasar fields.Comment: 19 pages, 12 figures, submitted to the Ap

Quasar Environments at z ~ 4

In the standard picture of structure formation, the first massive galaxies form in the highest peaks of the density field, which are the cores of massive proto-clusters. Such structures must be exceedingly rare, and thus hard to find. Luminous quasars (QSOs) at z ~ 4 are the most strongly clustered population in the Universe and this large auto-correlation demands that they reside in massive dark matter halos, associated with large overdensities of galaxies. This imply a strong QSO-galaxy cross-correlation for luminous QSOs at z ~ 4. In order to put the first observational constrain on the QSO-galaxy clustering properties, I present the measurement of the cross-correlation function between QSOs and both Lyman break galaxies (LBGs) and Lyman alpha emitters (LAEs) at z ~ 4. I present VLT/FORS1 observations of 6 luminous QSOs fields. Using a novel narrow band filter technique I select LBGs associated with each quasar in a narrow redshift range of Δz ~ 0.2. I measure the QSO-LBG cross correlation function on scales of 0.1 < R < 10 h-1 Mpc (comoving), which is well fitted by a power law form with a correlation length r0 = 9.91+3.28-1.79 h-1 Mpc and a slope gamma = 2.05+0.20-0.46. This is in agreement with the theoretical expected clustering computed from the individual QSO and LBGs auto-correlation, assuming a linear bias model. I also measure the auto-correlation of LBGs in the QSO fields, which shows a stronger clustering in comparison with LBGs in random fields. The new technique used for the detection of LBGs is efficient in selecting them in a thin redshift slice, but this shows important shortcomings whereby this result should be carefully considered. Additionally, I present VLT/FORS2 observations of 14 luminous QSO fields, designed to search for LAEs in their environments. I find that QSOs and LAEs are not correlated at z ~ 4, and the mean LAEs number density in our fields is consistent with the expected number density in random fields. This could mean either that the QSO auto-correlation length at z ~ 4 is overestimated, or that LAEs preferentially avoid QSO environments on ≲10 Mpc h-1 scales

The clustering of submillimeter galaxies detected with ALMA

Previous studies measuring the clustering of submillimeter galaxies (SMGs) have based their measurements on single-dish detected sources, finding evidence for strong clustering. However, ALMA has revealed that, due to the coarse angular resolution of these instruments, single-dish sources can be comprised of multiple sources. This implies that the clustering inferred from single-dish surveys may be overestimated. Here, we measure the clustering of SMGs based on the ALESS survey, an ALMA follow-up of sources previously identified in the LABOCA ECDFS Submillimeter Survey (LESS). We present a method to measure the clustering of ALMA sources that have been previously identified using single-dish telescopes, based on forward modeling both the single-dish and the ALMA observations. We constrain upper limits for the median mass of halos hosting SMGs at $

Spectroscopic Characterization of Galaxy Clusters in RCS-1: Spectroscopic Confirmation, Redshift Accuracy, and Dynamical Mass–Richness Relation

We present follow-up spectroscopic observations of galaxy clusters from the first Red-sequence Cluster Survey (RCS-1). This work focuses on two samples, a lower redshift sample of ∼30 clusters ranging in redshift from z ∼ 0.2–0.6 observed with multiobject spectroscopy (MOS) on 4–6.5-m class telescopes and a z ∼ 1 sample of ∼10 clusters 8-m class telescope observations. We examine the detection efficiency and redshift accuracy of the now widely used red-sequence technique for selecting clusters via overdensities of red-sequence galaxies. Using both these data and extended samples including previously published RCS-1 spectroscopy and spectroscopic redshifts from SDSS, we find that the red-sequence redshift using simple two-filter cluster photometric redshifts is accurate to σz ≈ 0.035(1 + z) in RCS-1. This accuracy can potentially be improved with better survey photometric calibration. For the lower redshift sample, ∼5 per cent of clusters show some (minor) contamination from secondary systems with the same red-sequence intruding into the measurement aperture of the original cluster. At z ∼ 1, the rate rises to ∼20 per cent. Approximately ten  per cent of projections are expected to be serious, where the two components contribute significant numbers of their red-sequence galaxies to another cluster. Finally, we present a preliminary study of the mass–richness calibration using velocity dispersions to probe the dynamical masses of the clusters. We find a relation broadly consistent with that seen in the local universe from the WINGS sample at z ∼ 0.05

Factors Associated With Short-Term Eradication of Rectal Colonization by KPC-2 Producing Klebsiella pneumoniae in an Outbreak Setting

Background: KPC-producing Klebsiella pneumoniae (KPCKP) is a threat for patients admitted to healthcare institutions. Objectives: To assess the efficacy of several decolonization strategies for KPCKP rectal carriage. Methods: Observational study performed in a 750-bed university center from July to October 2018 on the efficacy of a 10-day non-absorbable oral antibiotic (NAA) regimen (colistin 10 mg/ml, amikacin 8 mg/ml, and nystatin 30 mg/ml, 10 ml/6 h) vs. the same regimen followed by a probiotic (Vivomixx®) for 20 days in adult patients with KPCKP rectal colonization acquired during an outbreak. Results: Seventy-three patients colonized by KPCKP were included, of which 21 (29%) did not receive any treatment and 52 (71.2%) received NAA either alone (n = 26, 35.6%) or followed by a probiotic (n = 26, 35.6%). Eradication was observed in 56 (76.7%) patients and the only variable significantly associated with it was not receiving systemic antibiotics after diagnosis of rectal carriage [22/24 (91.6%) vs. 34/49 (69.3%), p = 0.04]. Eradication in patients receiving NAA plus probiotic was numerically but not significantly higher than that of controls [23/26 (88.4%) vs. 15/21 (71.4%), p = 0.14] and of those receiving only NAA (OR = 3.4, 95% CI = 0.78-14.7, p = 0.09). Conclusion: In an outbreak setting, rectal carriage of KPCKP persisted after a mean of 36 days in about one quarter of patients. The only factor associated with eradication was not receiving systemic antibiotic after diagnosis. A 10-day course of NAA had no impact on eradication. Probiotics after NAA may increase the decolonization rate, hence deserving further study

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

Perfil de los pacientes que acuden al médico internista para valoración de osteoporosis: registro OSTEOMED

Producción CientíficaAntecedentes y objetivo: La osteoporosis se considera un trastorno generalizado del esqueleto en el que existe una alteración de la resistencia ósea que predispone a la persona a un mayor riesgo de fractura. Este estudio transversal pretende recoger y presentar las principales características clínicas de los pacientes que acuden a la consulta de los médicos internistas en Espa˜na. Conocer estas características podría facilitar la puesta en marcha de planes de actuación para mejorar la atención de estos pacientes de manera más eficaz y eficiente. Material y métodos: A través del análisis del registro OSTEOMED (Osteoporosis en Medicina Interna), este trabajo presenta las principales características clínicas de los pacientes con osteoporosis que acudieron a las consultas de Medicina Interna en 23 centros hospitalarios espa˜noles entre 2012 y 2017. Se han analizado los motivos de consulta, los valores densitométricos, la presencia de comorbilidades, el tratamiento prescrito y otros factores relacionados con el estilo de vida. Resultados: En total se evaluó a 2.024 pacientes con osteoporosis (89,87% mujeres, 10,13% hombres). La edad media de los pacientes fue de 64,1 ± 12,1 a˜nos (mujeres, 64,7 ± 11,5 a˜nos; hombres, 61,2 ± 14,2 a˜nos). No hubo diferencia entre sexos en la historia de caídas recientes (9,1-6,7%), mientras que sí se apreció en la ingesta diaria de calcio de lácteos (553,8 ± 332,6 mg en mujeres vs. 450,2 ± 303,3 mg en hombres; p < 0,001) y en causas secundarias de osteoporosis(13% de hombres vs. 6,5% de mujeres; p < 0,001). En la muestra se observaron un total de 404fracturas (20%), destacando el número de fracturas vertebrales confirmadas (17,2%, 35,6% enhombres vs. 15,2% de las mujeres; p < 0,001). Una gran parte de los pacientes no recibía eltratamiento indicado y presentaba bajos niveles de actividad física y exposición solar. Un por-centaje importante de pacientes presentó comorbilidades asociadas, siendo las más frecuentesla hipertensión (32%) y la dislipidemia (28%).Conclusiones: Estos resultados definen el perfil del paciente con osteoporosis que acude a laconsulta de Medicina Interna en Espa˜na. Además, ponen de manifiesto el carácter multisistémicode esta entidad que junto con su elevada prevalencia determinan que las consultas específicasde Medicina Interna dedicadas a su manejo son el lugar adecuado para la atención de estos pacientes