196 research outputs found

    Probing the Inner Jet of the Quasar PKS 1510-089 with Multi-waveband Monitoring during Strong Gamma-ray Activity

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    We present results from monitoring the multi-waveband flux, linear polarization, and parsec-scale structure of the quasar PKS 1510-089, concentrating on eight major gamma-ray flares that occurred during the interval 2009.0-2009.5. The gamma-ray peaks were essentially simultaneous with maxima at optical wavelengths, although the flux ratio of the two wavebands varied by an order of magnitude. The optical polarization vector rotated by 720 degrees during a 5-day period encompassing six of these flares. This culminated in a very bright, roughly 1 day, optical and gamma-ray flare as a bright knot of emission passed through the highest-intensity, stationary feature (the "core") seen in 43 GHz Very Long Baseline Array images. The knot continued to propagate down the jet at an apparent speed of 22c and emit strongly at gamma-ray energies as a months-long X-ray/radio outburst intensified. We interpret these events as the result of the knot following a spiral path through a mainly toroidal magnetic field pattern in the acceleration and collimation zone of the jet, after which it passes through a standing shock in the 43 GHz core and then continues downstream. In this picture, the rapid gamma-ray flares result from scattering of infrared seed photons from a relatively slow sheath of the jet as well as from optical synchrotron radiation in the faster spine. The 2006-2009.7 radio and X-ray flux variations are correlated at very high significance; we conclude that the X-rays are mainly from inverse Compton scattering of infrared seed photons by 20-40 MeV electrons.Comment: 10 pages of text + 5 figures, to be published in Astrophysical Journal Letters in 201

    Plasma proteomic patterns show sex differences in early concentric left ventricular remodeling

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    BACKGROUND: Concentric remodeling (cRM) can precede heart failure with preserved ejection fraction (HFpEF), a condition prevalent in women. METHODS: Patients (n=60 593, 54.2% women) visiting outpatient clinics of Cardiology Centers of the Netherlands were analyzed for cRM, HFpEF development, and mortality risk. We studied risk factors for relative wall thickness both sex-stratified and in women and men combined. Biomarker profiling was performed (4534 plasma proteins) in a substudy involving 557 patients (65.4% women) to identify pathways involved in cRM. RESULTS: cRM was present in 23.5% of women and 27.6% of men and associated with developing HFpEF (HR, 2.15 [95% CI, 1.51-2.99]) and mortality risk (HR, 1.09 [95% CI, 1.00-1.19]) in both sexes. Age, heart rate, and hypertension were statistically significantly stronger risk factors for relative wall thickness in women than men. Higher circulating levels of IFNA5 (interferon alpha-5) were associated with higher relative wall thickness in women only. Pathway analysis revealed differential pathway activation by sex and increased expression of inflammatory pathways in women. CONCLUSIONS: cRM is prevalent in approximately 1 in 4 women and men visiting outpatient cardiology clinics and associated with HFpEF development and mortality risk in both sexes. Known risk factors for cRM were more strongly associated in women than men. Proteomic analysis revealed inflammatory pathway activation in women, with a central role for IFNA5. Differential biologic pathway activation by sex in cRM may contribute to the female predominance of HFpEF and holds promise for identification of new therapeutic avenues for prevention and treatment of HFpEF. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT001747

    On the Location of the Gamma-ray Emission in the 2008 Outburst in the BL Lacertae Object AO 0235+164 through Observations across the Electromagnetic Spectrum

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    We present observations of a major outburst at centimeter, millimeter, optical, X-ray, and gamma-ray wavelengths of the BL Lacertae object AO 0235+164. We analyze the timing of multi-waveband variations in the flux and linear polarization, as well as changes in Very Long Baseline Array (VLBA) images at 7mm with 0.15 milliarcsecond resolution. The association of the events at different wavebands is confirmed at high statistical significance by probability arguments and Monte-Carlo simulations. A series of sharp peaks in optical linear polarization, as well as a pronounced maximum in the 7 mm polarization of a superluminal jet knot, indicate rapid fluctuations in the degree of ordering of the magnetic field. These results lead us to conclude that the outburst occurred in the jet both in the quasi-stationary "core" and in the superluminal knot, both parsecs downstream of the supermassive black hole. We interpret the outburst as a consequence of the propagation of a disturbance, elongated along the line of sight by light-travel time delays, that passes through a standing recollimation shock in the core and propagates down the jet to create the superluminal knot. The multi-wavelength light curves vary together on long time-scales (months/years), but the correspondence is poorer on shorter time-scales. This, as well as the variability of the polarization and the dual location of the outburst, agrees with the expectations of a multi-zone emission model in which turbulence plays a major role in modulating the synchrotron and inverse Compton fluxes.Comment: Accepted for Publication in the Astrophysical Journal Letters. 7 pages (including 5 figures). Minor corrections with regard to previous version, as proposed by the refere

    Flaring Behavior of the Quasar 3C~454.3 across the Electromagnetic Spectrum

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    We analyze the behavior of the parsec-scale jet of the quasar 3C~454.3 during pronounced flaring activity in 2005-2008. Three major disturbances propagated down the jet along different trajectories with Lorentz factors Γ>\Gamma>10. The disturbances show a clear connection with millimeter-wave outbursts, in 2005 May/June, 2007 July, and 2007 December. High-amplitude optical events in the RR-band light curve precede peaks of the millimeter-wave outbursts by 15-50 days. Each optical outburst is accompanied by an increase in X-ray activity. We associate the optical outbursts with propagation of the superluminal knots and derive the location of sites of energy dissipation in the form of radiation. The most prominent and long-lasting of these, in 2005 May, occurred closer to the black hole, while the outbursts with a shorter duration in 2005 Autumn and in 2007 might be connected with the passage of a disturbance through the millimeter-wave core of the jet. The optical outbursts, which coincide with the passage of superluminal radio knots through the core, are accompanied by systematic rotation of the position angle of optical linear polarization. Such rotation appears to be a common feature during the early stages of flares in blazars. We find correlations between optical variations and those at X-ray and γ\gamma-ray energies. We conclude that the emergence of a superluminal knot from the core yields a series of optical and high-energy outbursts, and that the mm-wave core lies at the end of the jet's acceleration and collimation zone.Comment: 57 pages, 23 figures, 8 tables (submitted to ApJ

    The prevalence, incidence and risk factors of herpes simplex virus type 2 infection among pregnant Zimbabwean women followed up nine months after childbirth

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    Background Herpes simplex virus type 2 (HSV-2) is the leading cause of genital ulcer disease worldwide. The virus can be transmitted to neonates and there are scarce data regarding incidence of HSV-2 among women in pregnancy and after childbirth. The aim of this study is to measure the incidence and risk factors for HSV-2 infection in women followed for 9 months after childbirth. Methods Pregnant women were consecutively enrolled late in pregnancy and followed at six weeks, four and nine months after childbirth. Stored samples were tested for HSV-2 at baseline and again at nine months after childbirth and HSV-2 seropositive samples at nine months after childbirth (seroconverters) were tested retrospectively to identify the seroconversion point. Results One hundred and seventy-three (50.9%) of the 340 consecutively enrolled pregnant women were HSV-2 seronegative at baseline. HSV-2 incidence rate during the 10 months follow up was 9.7 (95% CI 5.4-14.4)/100 and 18.8 (95% CI 13.9-26.1)/100 person years at risk (PYAR) at four months and nine months after childbirth respectively. Analysis restricted to women reporting sexual activity yielded higher incidence rates. The prevalence of HSV-2 amongst the HIV-1 seropositive was 89.3%. Risk factors associated with HSV-2 seropositivity were having other sexual partners in past 12 months (Prevalence Risk Ratio (PRR) 1.8 (95% CI 1.4-2.4) and presence of Trichomonas vaginalis (PRR 1.7 95% CI 1.4-2.1). Polygamy (Incidence Rate Ratio (IRR) 4.4, 95% CI 1.9-10.6) and young age at sexual debut (IRR 3.6, 95% CI 1.6-8.3) were associated with primary HSV-2 infection during the 10 months follow up. Conclusions Incidence of HSV-2 after childbirth is high and the period between late pregnancy and six weeks after childbirth needs to be targeted for prevention of primary HSV-2 infection to avert possible neonatal infections

    Implementing evidence-based medicine in general practice: a focus group based study

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    BACKGROUND: Over the past years concerns are rising about the use of Evidence-Based Medicine (EBM) in health care. The calls for an increase in the practice of EBM, seem to be obstructed by many barriers preventing the implementation of evidence-based thinking and acting in general practice. This study aims to explore the barriers of Flemish GPs (General Practitioners) to the implementation of EBM in routine clinical work and to identify possible strategies for integrating EBM in daily work. METHODS: We used a qualitative research strategy to gather and analyse data. We organised focus groups between September 2002 and April 2003. The focus group data were analysed using a combined strategy of 'between-case' analysis and 'grounded theory approach'. Thirty-one general practitioners participated in four focus groups. Purposeful sampling was used to recruit participants. RESULTS: A basic classification model documents the influencing factors and actors on a micro-, meso- as well as macro-level. Patients, colleagues, competences, logistics and time were identified on the micro-level (the GPs' individual practice), commercial and consumer organisations on the meso-level (institutions, organisations) and health care policy, media and specific characteristics of evidence on the macro-level (policy level and international scientific community). Existing barriers and possible strategies to overcome these barriers were described. CONCLUSION: In order to implement EBM in routine general practice, an integrated approach on different levels needs to be developed

    Epilepsy, hippocampal sclerosis and febrile seizures linked by common genetic variation around SCN1A

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    Epilepsy comprises several syndromes, amongst the most common being mesial temporal lobe epilepsy with hippocampal sclerosis. Seizures in mesial temporal lobe epilepsy with hippocampal sclerosis are typically drug-resistant, and mesial temporal lobe epilepsy with hippocampal sclerosis is frequently associated with important co-morbidities, mandating the search for better understanding and treatment. The cause of mesial temporal lobe epilepsy with hippocampal sclerosis is unknown, but there is an association with childhood febrile seizures. Several rarer epilepsies featuring febrile seizures are caused by mutations in SCN1A, which encodes a brain-expressed sodium channel subunit targeted by many anti-epileptic drugs. We undertook a genome-wide association study in 1018 people with mesial temporal lobe epilepsy with hippocampal sclerosis and 7552 control subjects, with validation in an independent sample set comprising 959 people with mesial temporal lobe epilepsy with hippocampal sclerosis and 3591 control subjects. To dissect out variants related to a history of febrile seizures, we tested cases with mesial temporal lobe epilepsy with hippocampal sclerosis with (overall n = 757) and without (overall n = 803) a history of febrile seizures. Meta-analysis revealed a genome-wide significant association for mesial temporal lobe epilepsy with hippocampal sclerosis with febrile seizures at the sodium channel gene cluster on chromosome 2q24.3 [rs7587026, within an intron of the SCN1A gene, P = 3.36 × 10−9, odds ratio (A) = 1.42, 95% confidence interval: 1.26-1.59]. In a cohort of 172 individuals with febrile seizures, who did not develop epilepsy during prospective follow-up to age 13 years, and 6456 controls, no association was found for rs7587026 and febrile seizures. These findings suggest SCN1A involvement in a common epilepsy syndrome, give new direction to biological understanding of mesial temporal lobe epilepsy with hippocampal sclerosis with febrile seizures, and open avenues for investigation of prognostic factors and possible prevention of epilepsy in some children with febrile seizure

    Suitability of external controls for drug evaluation in Duchenne muscular dystrophy

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    OBJECTIVE: To evaluate the suitability of real-world data (RWD) and natural history data (NHD) for use as external controls in drug evaluations for ambulatory Duchenne muscular dystrophy (DMD). METHODS: The consistency of changes in the 6-minute walk distance (Δ6MWD) was assessed across multiple clinical trial placebo arms and sources of NHD/RWD. Six placebo arms reporting 48-week Δ6MWD were identified via literature review and represented 4 sets of inclusion/exclusion criteria (n = 383 patients in total). Five sources of RWD/NHD were contributed by Universitaire Ziekenhuizen Leuven, DMD Italian Group, The Cooperative International Neuromuscular Research Group, ImagingDMD, and the PRO-DMD-01 study (n = 430 patients, in total). Mean Δ6MWD was compared between each placebo arm and RWD/NHD source after subjecting the latter to the inclusion/exclusion criteria of the trial for baseline age, ambulatory function, and steroid use. Baseline covariate adjustment was investigated in a subset of patients with available data. RESULTS: Analyses included ∼1,200 patient-years of follow-up. Differences in mean Δ6MWD between trial placebo arms and RWD/NHD cohorts ranged from -19.4 m (i.e., better outcomes in RWD/NHD) to 19.5 m (i.e., worse outcomes in RWD/NHD) and were not statistically significant before or after covariate adjustment. CONCLUSIONS: We found that Δ6MWD was consistent between placebo arms and RWD/NHD subjected to equivalent inclusion/exclusion criteria. No evidence for systematic bias was detected. These findings are encouraging for the use of RWD/NHD to augment, or possibly replace, placebo controls in DMD trials. Multi-institution collaboration through the Collaborative Trajectory Analysis Project rendered this study feasible

    New genetic loci link adipose and insulin biology to body fat distribution.

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    Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms
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