587 research outputs found
Multifrequency Strategies for the Identification of Gamma-Ray Sources
More than half the sources in the Third EGRET (3EG) catalog have no firmly
established counterparts at other wavelengths and are unidentified. Some of
these unidentified sources have remained a mystery since the first surveys of
the gamma-ray sky with the COS-B satellite. The unidentified sources generally
have large error circles, and finding counterparts has often been a challenging
job. A multiwavelength approach, using X-ray, optical, and radio data, is often
needed to understand the nature of these sources. This chapter reviews the
technique of identification of EGRET sources using multiwavelength studies of
the gamma-ray fields.Comment: 35 pages, 22 figures. Chapter prepared for the book "Cosmic Gamma-ray
Sources", edited by K.S. Cheng and G.E. Romero, to be published by Kluwer
Academic Press, 2004. For complete article and higher resolution figures, go
to: http://www.astro.columbia.edu/~muk/mukherjee_multiwave.pd
ERP evidence suggests executive dysfunction in ecstasy polydrug users
Background: Deficits in executive functions such as access to semantic/long-term memory have been shown in ecstasy users in previous research. Equally, there have been many reports of equivocal findings in this area. The current study sought to further investigate behavioural and electro-physiological measures of this executive function in ecstasy users.
Method: Twenty ecstasy–polydrug users, 20 non-ecstasy–polydrug users and 20 drug-naïve controls were recruited. Participants completed background questionnaires about their drug use, sleep quality, fluid intelligence and mood state. Each individual also completed a semantic retrieval task whilst 64 channel Electroencephalography (EEG) measures were recorded.
Results: Analysis of Variance (ANOVA) revealed no between-group differences in behavioural performance on the task. Mixed ANOVA on event-related potential (ERP) components P2, N2 and P3 revealed significant between-group differences in the N2 component. Subsequent exploratory univariate ANOVAs on the N2 component revealed marginally significant between-group differences, generally showing greater negativity at occipito-parietal electrodes in ecstasy users compared to drug-naïve controls. Despite absence of behavioural differences, differences in N2 magnitude are evidence of abnormal executive functioning in ecstasy–polydrug users
On-shell Recursion in String Theory
We prove that all open string theory disc amplitudes in a flat background
obey Britto-Cachazo-Feng-Witten (BCFW) on-shell recursion relations, up to a
possible reality condition on a kinematic invariant. Arguments that the same
holds for tree level closed string amplitudes are given as well. Non-adjacent
BCFW-shifts are related to adjacent shifts through monodromy relations for
which we provide a novel CFT based derivation. All possible recursion relations
are related by old-fashioned string duality. The field theory limit of the
analysis for amplitudes involving gluons is explicitly shown to be smooth for
both the bosonic string as well as the superstring. In addition to a proof a
less rigorous but more powerful argument based on the underlying CFT is
presented which suggests that the technique may extend to a much more general
setting in string theory. This is illustrated by a discussion of the open
string in a constant B-field background and the closed string on the level of
the sphere.Comment: 36 + 9 pages text, one figure, v3: added discussion on relation to
old-fashioned factorization, typos corrected, published versio
Changing treatment patterns for coronary artery revascularization in Canada: the projected impact of drug eluting stents
BACKGROUND: To evaluate current treatment patterns for coronary artery revascularization in Canada and explore the potential impact of drug eluting stents (DES) on these treatment patterns. METHODS: Eleven cardiologists at multiple Canadian academic centers completed a questionnaire on coronary artery revascularization rates and treatment patterns. RESULTS: Participating physicians indicated slightly higher rates of PTCA, CABG, and stent implantation than reported in CCN publications. Participants estimated that 24% of all patients currently receiving bare metal stents (BMS) would receive DES in the first year following DES approval in Canada, although there was a large range of estimates around this value (5% to 65%). By the fifth year following DES approval, it was estimated that 85% of BMS patients would instead receive DES. Among diabetic patients, estimates ranged from 43% in the first year following approval to 91% in the fifth year. For all patients currently receiving CABG, mean use of DES instead was estimated at 12% in the first year to 42% at five years; rates among diabetic patients currently undergoing CABG were 17% in the first year to 49% in the fifth year. CONCLUSIONS: These results suggest a continued increase in revascularization procedures in Canada. Based on the panel's responses, it is likely that a trend away from CABG towards PTCA will continue in Canada, and will be augmented by the availability of DES as a treatment option. The availability of DES as a treatment option in Canada may change the threshold at which revascularization procedures are considered
Caregiver delivered sensory electrical stimulation for post stroke upper limb spasticity: A single blind crossover randomized feasibility study
We developed a 64 channel sensory electrical stimulator which delivers a dynamic and variable ‘Sensory Barrage’ Stimulation (SBS). Our aim was to assess the feasibility of caregivers delivering the stimulation in the community for a clinical trial comparing single channel Transcutaneous Electrical Nerve Stimulation (TENS) with SBS for post stroke upper limb spasticity. We trained caregivers of 16 participants with post stroke upper limb spasticity to sequentially administer SBS and TENS for 60 min daily for four weeks each, with a washout period of two weeks in between. Outcome measures tested were recruitment and retention rates, compliance with interventions and daily recording of Participant -reported Numerical Rating Scale (NRS). We also collected results of Action Research Arm Test (ARAT), Leeds Arm Spasticity Impact Scale (LASIS) and Modified Ashworth Scale (MAS) for spasticity. Out of 21 potential participants, 16 consented and 15 completed the protocol. Ten participants received TENS for 80% (23/28) of the intended hours. Eleven participants completed NRS for at 80% (45/56) of the study days. All participants attended all visits. The MAS reduced by at least one in five participants after SBS and in three after TENS. Minimal Clinically Important Difference (MCID) of four points increase in ARAT was seen in five participants following TENS, and in four following SBS. A MCID of 18% decrease in NRS was reported by eight participants after TENS and three after SBS. This study demonstrated the feasibility of undertaking a trial of sensory electrical stimulation for post-stroke spasticity with caregivers delivering intervention in community. The study was not powered to detect efficacy of the interventions. Trial registration number: NCT02907775.Date 20-9-2016
Cognitive Profiles and Education of Female Cyber Defence Operators
acceptedVersionpublishedVersio
Point-of-View: Arguments for conventional fisheries management and against no-take marine protected areas: only half of the story?
X-ray Absorption and Reflection in Active Galactic Nuclei
X-ray spectroscopy offers an opportunity to study the complex mixture of
emitting and absorbing components in the circumnuclear regions of active
galactic nuclei, and to learn about the accretion process that fuels AGN and
the feedback of material to their host galaxies. We describe the spectral
signatures that may be studied and review the X-ray spectra and spectral
variability of active galaxies, concentrating on progress from recent Chandra,
XMM-Newton and Suzaku data for local type 1 AGN. We describe the evidence for
absorption covering a wide range of column densities, ionization and dynamics,
and discuss the growing evidence for partial-covering absorption from data at
energies > 10 keV. Such absorption can also explain the observed X-ray spectral
curvature and variability in AGN at lower energies and is likely an important
factor in shaping the observed properties of this class of source.
Consideration of self-consistent models for local AGN indicates that X-ray
spectra likely comprise a combination of absorption and reflection effects from
material originating within a few light days of the black hole as well as on
larger scales. It is likely that AGN X-ray spectra may be strongly affected by
the presence of disk-wind outflows that are expected in systems with high
accretion rates, and we describe models that attempt to predict the effects of
radiative transfer through such winds, and discuss the prospects for new data
to test and address these ideas.Comment: Accepted for publication in the Astronomy and Astrophysics Review. 58
pages, 9 figures. V2 has fixed an error in footnote
Internal gallbladder drainage prevents development of acute cholecystitis in a pig model: a randomized study
A Molecular Study on the Prevalence and Virulence Potential of Aeromonas spp. Recovered from Patients Suffering from Diarrhea in Israel
Background: Species of the genus Aeromonas are native inhabitants of aquatic environments and have recently been considered emerging human pathogens. Although the gastrointestinal tract is by far the most common anatomic site from which aeromonads are recovered, their role as etiologic agents of bacterial diarrhea is still disputed. Aeromonas-associated diarrhea is a phenomenon occurring worldwide; however, the exact prevalence of Aeromonas infections on a global scale is unknown. Methodology/Principal Findings: The prevalence and virulence potential of Aeromonas in patients suffering from diarrhea in Israel was studied using molecular methods. 1,033 diarrheal stools were sampled between April and September 2010 and Aeromonas species were identified in 17 (,2%) patients by sequencing the rpoD gene. Aeromonas species identity and abundance was: A. caviae (65%), A. veronii (29%) and Aeromonas taiwanensis (6%). This is the first clinical record of A. taiwanensis as a diarrheal causative since its recent discovery from a wound infection in a patient in Taiwan. Most of the patients (77%) from which Aeromonas species were isolated were negative for any other pathogens. The patients ranged from 1 to 92 years in age. Aeromonas isolates were found to possess different virulence-associated genes: ahpB (88%), pla/ lip/lipH3/apl-1 (71%), act/hlyA/aerA (35%), alt (18%), ast (6%), fla (65%), lafA (41%), TTSS ascV (12%), TTSS ascF-ascG (12%), TTSS-dependent ADP-ribosylating toxins aexU (41%) and aexT (6%) in various combinations. Most of the identified strain
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