577 research outputs found
Observations of one young and three middle-aged -ray pulsars with the Gran Telescopio Canarias
We used the 10.4m Gran Telescopio Canarias to search for the optical
counterparts to four isolated -ray pulsars, all detected in the X-rays
by either \xmm\ or \chan\ but not yet in the optical. Three of them are
middle-aged pulsars -- PSR\, J1846+0919 (0.36 Myr), PSR\, J2055+2539 (1.2 Myr),
PSR\, J2043+2740 (1.2 Myr) -- and one, PSR\, J1907+0602, is a young pulsar
(19.5 kyr). For both PSR\, J1907+0602 and PSR\, J2055+2539 we found one object
close to the pulsar position. However, in both cases such an object cannot be a
viable candidate counterpart to the pulsar. For PSR\, J1907+0602, because it
would imply an anomalously red spectrum for the pulsar and for PSR\, J2055+2539
because the pulsar would be unrealistically bright () for the
assumed distance and interstellar extinction. For PSR\, J1846+0919, we found no
object sufficiently close to the expected position to claim a possible
association, whereas for PSR\, J2043+2740 we confirm our previous findings that
the object nearest to the pulsar position is an unrelated field star. We used
our brightness limits (), the first obtained with a
large-aperture telescope for both PSR\, J1846+0919 and PSR\, J2055+2539, to
constrain the optical emission properties of these pulsars and investigate the
presence of spectral turnovers at low energies in their multi-wavelength
spectra.Comment: 10 pages, 11 figures, accpted for publication in MNRA
Observations of three young gamma-ray pulsars with the Gran Telescopio Canarias
We report the analysis of the first deep optical observations of three
isolated -ray pulsars detected by the {\em Fermi Gamma-ray Space
Telescope}: the radio-loud PSR\, J0248+6021 and PSR\, J0631+1036, and the
radio-quiet PSR\, J0633+0632. The latter has also been detected in the X rays.
The pulsars are very similar in their spin-down age (40--60 kyrs),
spin-down energy ( erg s), and dipolar surface
magnetic field (-- G). These pulsars are promising
targets for multi-wavelength observations, since they have been already
detected in rays and in radio or X-rays. None of them has been
detected yet in the optical band. We observed the three pulsar fields in 2014
with the Spanish 10.4m Gran Telescopio Canarias (GTC). We could not find any
candidate optical counterpart to the three pulsars close to their most recent
radio or {\em Chandra} positions down to limits of ,
, for PSR\, J0248+6021, J0631+1036, and J0633+0632,
respectively. From the inferred optical upper limits and estimated distance and
interstellar extinction, we derived limits on the pulsar optical luminosity. We
also searched for the X-ray counterpart to PSR\, J0248+6021 with \chan\ but we
did not detect the pulsar down to a 3 flux limit of
erg cm s (0.3--10 keV). For all these pulsars, we compared the
optical flux upper limits with the extrapolations in the optical domain of the
-ray spectra and compared their multi-wavelength properties with those
of other -ray pulsars of comparable age.Comment: 12 pages, 5 figures, accepted for publication in MNRA
Interaction of Metallic Iron with Solutions Containing Humic Acids and Cu(II)
Humic acids are responsible for the heavy metal movement in the environment. In order to diminish soil pollution with heavy metals the treatment of groundwater with metallic iron has been proposed. Investigations with model solutions containing humic acids and Cu(II) have shown that metallic iron is an effective decontaminant for humic acids containing solutions. The application of the mechanical brush-up of the passive layers from surface using rotating systems loaded with iron pieces gives satisfactory results. The decontamination rate depends mainly on solution pH and the iron surface renewal rate. The presence of Cu(II) ions in the solution or metallic copper in the load increase the decontamination rate
Texting Sexual Health Pilot - Interview Guide
A semi-structured topic guide used to discover participants’ views, experiences, and recommendations for improvements to behavioral intervention on sexual health. Questions cover tone and frequency of text messages, views regarding the message content, any concerns about others viewing texts, what (if anything) they had learned from text messages, sexual behavior since enrolment (such as condom use and partner notification), and suggested improvements to the intervention
NuSTAR Hard X-ray Observation of the Gamma-ray Binary Candidate HESS J1832-093
We present a hard X-ray observation of the TeV gamma-ray binary candidate
HESS J1832-093 coincident with supernova remnant (SNR) G22.7-0.2 using the
Nuclear Spectroscopic Telescope Array (NuSTAR). Non-thermal X-ray emission from
XMMU J183245-0921539, the X-ray source associated with HESS J1832-093, is
detected up to ~30 keV and is well-described by an absorbed power-law model
with the best-fit photon index . A re-analysis of archival
Chandra and XMM-Newton data finds that the long-term X-ray flux increase of
XMMU J183245-0921539 is % (90% C.L.), much less than previously
reported. A search for a pulsar spin period or binary orbit modulation yields
no significant signal to a pulse fraction limit of fp < 19% in the range 4 ms <
P < 40 ks. No red noise is detected in the FFT power spectrum to suggest active
accretion from a binary system. While further evidence is required, we argue
that the X-ray and gamma-ray properties of XMMU J183245-0921539 are most
consistent with a non-accreting binary generating synchrotron X- rays from
particle acceleration in the shock formed as a result of the pulsar and stellar
wind collision. We also report on three nearby hard X-ray sources, one of which
may be associated with diffuse emission from a fast-moving supernova fragment
interacting with a dense molecular cloud.Comment: ApJ in press. 9 page
Safety and clinical activity of atacicept in the long-term extension of the Phase IIb ADDRESS II study in systemic lupus erythematosus
Objectives:
Atacicept reduced SLE disease activity in the Phase IIb ADDRESS II study, particularly in patients with high disease activity (HDA; SLEDAI-2K ≥10) at screening. We assessed long-term safety and efficacy of atacicept in the long-term extension (LTE) of ADDRESS II.
Methods:
In the 24-week, randomised, double-blind, placebo-controlled ADDRESS II study, patients received weekly atacicept (75 or 150 mg) or placebo. Atacicept was continued at the same dose in atacicept-treated patients in the LTE; placebo-treated patients switched to atacicept 150 mg. Long-term safety was the primary end point. Secondary endpoints included SLE responder index (SRI)-4 and SRI-6 response rates and flares.
Results:
253 patients entered the ADDRESS II LTE; 88 received atacicept 150 mg, 82 atacicept 75 mg and 83 placebo/atacicept 150 mg. Median active treatment duration in the LTE was 83.8 weeks. Frequencies of treatment-emergent adverse events (TEAEs) were similar across groups (90.4–93.2%). 12.5%, 14.6% and 21.7% of patients in the atacicept 150 mg, atacicept 75 mg and placebo/atacicept 150 mg groups reported serious TEAEs during the treatment period. The proportions of patients with TEAEs leading to discontinuation were 5.7%, 4.9% and 10.8%, respectively. SRI-4 and SRI-6 response rates were maintained with atacicept in the modified intent-to-treat and HDA populations and those on continuous 150 mg had a reduced risk of first severe flare and longer time to first severe flare vs those who initially received placebo.
Conclusion:
Long-term treatment with atacicept 150 mg in SLE patients had an acceptable safety profile, with durable efficacy
Safetxt: a pilot randomised controlled trial of an intervention delivered by mobile phone to increase safer sex behaviours in young people.
OBJECTIVE: To test the procedures proposed for a main trial of a safer sex intervention for young people delivered by mobile phone text message ('safetxt'). DESIGN AND SETTING: Pilot randomised controlled trial. Participants were recruited through sexual health services in the UK. An independent online randomisation system allocated participants to receive the safetxt intervention or to receive the control text messages (monthly messages about participation in the study). Texting software delivered the messages in accordance with a predetermined schedule. PARTICIPANTS: Residents of England aged 16-24 who had received either a positive chlamydia test result or reported unsafe sex in the last year (defined as more than 1 partner and at least 1 occasion of sex without a condom). INTERVENTION: The safetxt intervention is designed to reduce sexually transmitted infection in young people by supporting them in using condoms, telling a partner about an infection and testing before unprotected sex with a new partner. Safetxt was developed drawing on: behavioural science; face-to-face interventions; the factors known to influence safer sex behaviours and the views of young people. OUTCOMES: The coprimary outcomes of the pilot trial were the recruitment rate and completeness of follow-up. RESULTS: We recruited 200 participants within our target of 3 months and we achieved 81% (162/200) follow-up response for the proposed primary outcome of the main trial, cumulative incidence of chlamydia at 12 months. CONCLUSIONS: Recruitment, randomisation, intervention delivery and follow-up were successful and a randomised controlled trial of the safetxt intervention is feasible. TRIAL REGISTRATION NUMBER: ISRCTN02304709; Results
Young People's Views and Experiences of a Mobile Phone Texting Intervention to Promote Safer Sex Behavior.
BACKGROUND: The risk of poor sexual health, including unplanned pregnancy and sexually transmitted infections (STIs), is greatest amongst young people. Innovative and acceptable interventions to improve sexual health are required. Mobile phone text messaging (short message service, SMS) interventions have the potential to reach large numbers of people at relatively low cost, but greater understanding is needed on how these interventions should be developed and how they work. OBJECTIVES: The aim of this paper is to explore young people's views of and experiences with a mobile phone text messaging intervention to promote safer sex behavior. METHODS: We undertook qualitative interviews with young people aged 16 to 24 years as part of a pilot trial of a sexual health intervention delivered by text message in the United Kingdom. Study participants received sexual health promotion text messages based on behavior-change techniques. The message content, tailored by gender and STI status, included support for correct STI treatment and promotion of safer sex behaviors. Young people were eligible if they had received a positive chlamydia test or had more than one partner and at least one episode of unprotected sex in the last year. Telephone interviews were conducted 2 to 3 weeks after initiation of the intervention. A semi-structured topic guide was followed to explore participant experiences and a thematic analysis was conducted. RESULTS: We conducted 16 telephone interviews with participants who had received the text intervention and an additional four interviews with those in the control group (13 women and 7 men). Intervention participants found text messages easy to understand and appearing to come from a friendly and trustworthy source. They considered the frequency and timing of messages to be appropriate, and delivery via mobile phones convenient. Receipt of support by text message allowed recipients to assimilate information at their own pace, and prompted reflection on and sharing of messages with friends, family members, and partners, thus providing opportunities for education and discussion. For some recipients, the messages had increased their knowledge of how to correctly use condoms. Some described how the messages had increased their confidence and reduced stigma, enabling them to disclose infection to a partner and/or to do so sooner and more calmly. Discussing the messages with a partner reportedly enabled some women to negotiate condom use. CONCLUSION: From the perspective of the recipients, the tone, frequency, and content of the text messaging-based sexual health intervention was acceptable and appropriate. Their accounts indicated that the intervention increased knowledge, confidence, and safer sex behaviors. A large-scale randomized controlled trial (RCT) is needed to assess effectiveness
Is the giant radio galaxy M 87 a TeV gamma-ray emitter?
For the first time an excess of photons above an energy threshold of 730 GeV from the giant radio galaxy M 87 has been measured at a significance level above 4 σ. The data have been taken during the years 1998 and 1999 with the HEGRA stereoscopic system of 5 imaging atmospheric Cherenkov telescopes. The excess of 107.4 ± 26.8 events above 730 GeV corresponds to an integral flux of 3.3% of the Crab flux or Nγ (E > 730 GeV) = (0.96 ± 0.23) × 10-12 phot cm-2 s-1. M 87 is located at the center of the Virgo cluster of galaxies at a relatively small redshift of z = 0.00436 and is a promising candidate among the class of giant radio galaxies for the emission of TeV γ-radiation. The detection of TeV γ-rays from M 87 - if confirmed - would establish a new class of extragalactic source in this energy regime since all other AGN detected to date at TeV energies are BL Lac type objects.F. A. Aharonian ...G. P. Rowell...et al
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