126 research outputs found
A variable near-infrared counterpart to the neutron-star low-mass X-ray binary 4U 1705-440
We report the discovery of a near-infrared (nIR) counterpart to the
persistent neutron-star low-mass X-ray binary 4U 1705-440, at a location
consistent with its recently determined Chandra X-ray position. The nIR source
is highly variable, with K_s-band magnitudes varying between 15.2 and 17.3 and
additional J- and H-band observations revealing color variations. A comparison
with contemporaneous X-ray monitoring observations shows that the nIR
brightness correlates well with X-ray flux and X-ray spectral state. We also
find possible indications for a change in the slope of the nIR/X-ray flux
relation between different X-ray states. We discuss and test various proposed
mechanisms for the nIR emission from neutron-star low-mass X-ray binaries and
conclude that the nIR emission in 4U 1705-440 is most likely dominated by X-ray
heating of the outer accretion disk and the secondary star.Comment: Accepted for publication in Ap
Diffusive and ballistic current spin-polarization in magnetron-sputtered L1o-ordered epitaxial FePt
We report on the structural, magnetic, and electron transport properties of a
L1o-ordered epitaxial iron-platinum alloy layer fabricated by
magnetron-sputtering on a MgO(001) substrate. The film studied displayed a long
range chemical order parameter of S~0.90, and hence has a very strong
perpendicular magnetic anisotropy. In the diffusive electron transport regime,
for temperatures ranging from 2 K to 258 K, we found hysteresis in the
magnetoresistance mainly due to electron scattering from magnetic domain walls.
At 2 K, we observed an overall domain wall magnetoresistance of about 0.5 %. By
evaluating the spin current asymmetry alpha = sigma_up / sigma_down, we were
able to estimate the diffusive spin current polarization. At all temperatures
ranging from 2 K to 258 K, we found a diffusive spin current polarization of >
80%. To study the ballistic transport regime, we have performed point-contact
Andreev-reflection measurements at 4.2 K. We obtained a value for the ballistic
current spin polarization of ~42% (which compares very well with that of a
polycrystalline thin film of elemental Fe). We attribute the discrepancy to a
difference in the characteristic scattering times for oppositely spin-polarized
electrons, such scattering times influencing the diffusive but not the
ballistic current spin polarization.Comment: 22 pages, 13 figure
Feasibility study to assess the impact of a lifestyle intervention (‘LivingWELL’) in people having an assessment of their family history of colorectal or breast cancer
Objectives To assess the feasibility of delivering and evaluating a weight management (WM) programme for overweight patients with a family history (FH) of breast cancer (BC) or colorectal cancer (CRC). Study design A two-arm (intervention vs usual care) randomised controlled trial. Setting National Health Service (NHS) Tayside and NHS Grampian. Participants People with a FH of BC or CRC aged≥18 years and body mass index of ≥25 kg/m2 referred to NHS genetic services. Intervention Participants were randomised to a control (lifestyle booklet) or 12-week intervention arm where they were given one face-to-face counselling session, four telephone consultations and web-based support. A goal of 5% reduction in body weight was set, and a personalised diet and physical activity (PA) programme was provided. Behavioural change techniques (motivational interviewing, action and coping plans and implementation intentions) were used. Primary outcome Feasibility measures: recruitment, programme implementation, fidelity measures, achieved measurements and retention, participant satisfaction assessed by questionnaire and qualitative interviews. Secondary outcomes Measured changes in weight and PA and reported diet and psychosocial measures between baseline and 12-week follow-up. Results Of 480 patients approached, 196 (41%) expressed interest in the study, and of those, 78 (40%) patients were randomised. Implementation of the programme was challenging within the time allotted and fidelity to the intervention modest (62%). Qualitative findings indicated the programme was well received. Questionnaires and anthropometric data were completed by >98%. Accelerometer data were attained by 84% and 54% at baseline and follow-up, respectively. Retention at 12 weeks was 76%. Overall, 36% of the intervention group (vs 0% in control) achieved 5% weight loss. Favourable increases in PA and reduction in dietary fat were also reported. Conclusions A lifestyle programme for people with a family history of cancer is feasible to conduct and acceptable to participants, and indicative results suggest favourable outcomes. Trial registration number ISRCTN13123470; Pre-results
Dose-Dependent Effect of Platinum-Based Chemotherapy on the Risk of Metachronous Contralateral Testicular Cancer
PURPOSE: Patients with testicular germ cell tumor (TGCT) are at increased risk of developing a contralateral TGCT (CTGCT). Although some studies suggest that prior treatment with platinum-based chemotherapy affects CTGCT risk, a relationship between CTGCT risk and platinum dose has not previously been assessed. We analyzed the association between the number of platinum-based chemotherapy cycles and CTGCT risk. PATIENTS AND METHODS: The risk of developing a metachronous CTGCT was evaluated in a nationwide cohort of 4,755 patients diagnosed with primary TGCT in the Netherlands between 1989 and 2007. Standardized incidence ratios were computed to compare CTGCT incidence with expected TGCT on the basis of TGCT incidence in the general population. The cumulative incidence of CTGCT was estimated in the presence of death as competing risk. The effect of treatment with platinum-based chemotherapy on CTGCT risk was assessed using multivariable Cox proportional hazards regression models. RESULTS: CTGCT was diagnosed in 136 patients (standardized incidence ratio, 14.6; 95% CI, 12.2 to 17.2). The cumulative incidence increased up to 20 years after primary diagnosis, reaching 3.4% (95% CI, 2.8% to 4.0%) after 20 years of follow up. The risk of developing a CTGCT decreased with age (hazard ratio [HR], 0.93; 95% CI, 0.90 to 0.96), was lower after nonseminomatous germ cell tumor (HR, 0.58; 95% CI, 0.35 to 0.96) and decreased with every additional cycle of chemotherapy (HRper cycle, 0.74; 95% CI, 0.64 to 0.85). CONCLUSION: Approximately one in every 30 survivors of TGCT will develop a CTGCT, with CTGCT incidence increasing up to 20 years after a primary TGCT. Treatment with platinum-based chemotherapy shows a dose-dependent inverse association with CTGCT risk
Pretransplant sequential hypo- and normothermic machine perfusion of suboptimal livers donated after circulatory death using a hemoglobin-based oxygen carrier perfusion solution
Ex situ dual hypothermic oxygenated machine perfusion (DHOPE) and normothermic machine perfusion (NMP) of donor livers may have a complementary effect when applied sequentially. While DHOPE resuscitates the mitochondria and increases hepatic adenosine triphosphate (ATP) content, NMP enables hepatobiliary viability assessment prior to transplantation. In contrast to DHOPE, NMP requires a perfusion solution with an oxygen carrier, for which red blood cells (RBC) have been used in most series. RBC, however, have limitations and cannot be used cold. We, therefore, established a protocol of sequential DHOPE, controlled oxygenated rewarming (COR), and NMP using a new hemoglobin-based oxygen carrier (HBOC)-based perfusion fluid (DHOPE-COR-NMP trial, NTR5972). Seven livers from donation after circulatory death (DCD) donors, which were initially declined for transplantation nationwide, underwent DHOPE-COR-NMP. Livers were considered transplantable if perfusate pH and lactate normalized, bile production was >= 10 mL and biliary pH > 7.45 within 150 minutes of NMP. Based on these criteria five livers were transplanted. The primary endpoint, 3-month graft survival, was a 100%. In conclusion, sequential DHOPE-COR-NMP using an HBOC-based perfusion fluid offers a novel method of liver machine perfusion for combined resuscitation and viability testing of suboptimal livers prior to transplantation
Investigating ChaMPlane X-ray sources in the Galactic Bulge with Magellan LDSS2 spectra
We have carried out optical and X-ray spectral analyses on a sample of 136
candidate optical counterparts of X-ray sources found in five Galactic-bulge
fields included in our Chandra Multi-wavelength Plane Survey. We use a
combination of optical spectral fitting and quantile X-ray analysis to obtain
the hydrogen column density towards each object, and a three-dimensional dust
model of the Galaxy to estimate the most probable distance in each case. We
present the discovery of a population of stellar coronal emission sources,
likely consisting of pre-main sequence, young main sequence and main sequence
stars, as well as a component of active binaries of RS CVn or BY Dra type. We
identify one candidate quiescent low-mass X-ray binary with a sub-giant
companion; we note that this object may also be an RS CVn system. We report the
discovery of three new X-ray detected cataclysmic variables (CVs) in the
direction of the Galactic Center (at distances ~2kpc). This number is in excess
of predictions made with a simple CV model based on a local CV space density of
<~ 10^-5 pc^-3, and a scale height ~200pc. We discuss several possible reasons
for this observed excess.Comment: 41 pages, 11 figures. Accepted for publication in Astrophysical
Journal, September 10 editio
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Changes in the distribution of red foxes (Vulpes vulpes) in urban areas in Great Britain: findings and limitations of a media-driven nationwide survey
Urbanization is one of the major forms of habitat alteration occurring at the present time. Although this is typically deleterious to biodiversity, some species flourish within these human-modified landscapes, potentially leading to negative and/or positive interactions between people and wildlife. Hence, up-to-date assessment of urban wildlife populations is important for developing appropriate management strategies. Surveying urban wildlife is limited by land partition and private ownership, rendering many common survey techniques difficult. Garnering public involvement is one solution, but this method is constrained by the inherent biases of non-standardised survey effort associated with voluntary participation. We used a television-led media approach to solicit national participation in an online sightings survey to investigate changes in the distribution of urban foxes in Great Britain and to explore relationships between urban features and fox occurrence and sightings density. Our results show that media-based approaches can generate a large national database on the current distribution of a recognisable species. Fox distribution in England and Wales has changed markedly within the last 25 years, with sightings submitted from 91% of urban areas previously predicted to support few or no foxes. Data were highly skewed with 90% of urban areas having <30 fox sightings per 1000 people km-2. The extent of total urban area was the only variable with a significant impact on both fox occurrence and sightings density in urban areas; longitude and percentage of public green urban space were respectively, significantly positively and negatively associated with sightings density only. Latitude, and distance to nearest neighbouring conurbation had no impact on either occurrence or sightings density. Given the limitations associated with this method, further investigations are needed to determine the association between sightings density and actual fox density, and variability of fox density within and between urban areas in Britain
Health behaviors and their relationship with disease control in people attending genetic clinics with a family history of breast or colorectal cancer
The current work aimed to assess health behaviors, perceived risk and control over breast/colorectal cancer risk and views on lifestyle advice amongst attendees at cancer family history clinics. Participants attending the East of Scotland Genetics Service were invited to complete a questionnaire (demographic data, weight and height, health behaviors and psycho-social measures of risk and perceived control) and to participate in an in-depth interview. The questionnaire was completed by 237 (49%) of attendees, ranging from 18 to 77years (mean age 46 (±10) years). Reported smoking rates (11%) were modest, most (54%) had a BMI>25kg/m2, 55% had low levels of physical activity, 58% reported inappropriate alcohol intakes and 90% had fiber intakes indicative of a low plant diet. Regression analysis indicated that belief in health professional control was associated with higher, and belief in fatalism with poorer health behavior. Qualitative findings highlighted doubts about the link between lifestyle and cancer, and few were familiar with the current evidence. Whilst lifestyle advice was considered interesting in general there was little appetite for non-tailored guidance. In conclusion, current health behaviors are incongruent with cancer risk reduction guidance amongst patients who have actively sought advice on disease risk. There are some indications that lifestyle advice would be welcomed but endorsement requires a sensitive and flexible approach, and the acceptability of lifestyle interventions remains to be explored
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