863 research outputs found
Short-term H{\alpha} line variations in Classical Be stars: 59 Cyg and OT Gem
We present the optical spectroscopic study of two Classical Be stars, 59 Cyg
and OT Gem obtained over a period of few months in 2009. We detected a rare
triple-peak H emission phase in 59 Cyg and a rapid decrease in the
emission strength of H in OT Gem, which are used to understand their
circumstellar disks. We find that 59 Cyg is likely to be rapid rotator,
rotating at a fractional critical rotation of 0.80. The radius of the
H emission region for 59 Cyg is estimated to be 10.0,
assuming a Keplerian disk, suggesting that it has a large disk. We classify
stars which have shown triple-peaks into two groups and find that the
triple-peak emission in 59 Cyg is similar to Tau. OT Gem is found to
have a fractional critical rotation of 0.30, suggesting that it is
either a slow rotator or viewed in low inclination. In OT Gem, we observed a
large reduction in the radius of the H emission region from 6.9
to 1.7 in a period of three months, along with the reduction in the
emission strength. Our observations suggest that the disk is lost from outside
to inside during this disk loss phase in OT Gem.Comment: 12 pages, 3 figures, Accepted for publication in Journal of
Astrophysics and Astronomy. arXiv admin note: text overlap with
arXiv:1602.0293
Coronal Elemental Abundances during A-class Solar Flares Observed by Chandrayaan-2 XSM
The abundances of low First Ionisation Potential (FIP) elements are three to
four times higher (FIP bias) in the closed loop active corona than in the
photosphere, known as the FIP effect. Observations suggest that the abundances
vary in different coronal structures. Here, we use the soft X-ray spectroscopic
measurements from the Solar X-ray Monitor (XSM) on board the Chandrayaan-2
orbiter to study the FIP effect in multiple A-class flares observed during the
minimum of solar cycle 24. Using time-integrated spectral analysis, we derive
the average temperature, emission measure, and the abundances of four elements
- Mg, Al, Si, and S. We find that the temperature and emission measure scales
with the flares sub-class while the measured abundances show an intermediate
FIP bias for the lower A-flares (e.g., A1), while for the higher A-flares, the
FIP bias is near unity. To investigate it further, we perform a time-resolved
spectral analysis for a sample of the A-class flares and examine the evolution
of temperature, emission measure, and abundances. We find that the abundances
drop from the coronal values towards their photospheric values in the impulsive
phase of the flares, and after the impulsive phase, they quickly return to the
usual coronal values. The transition of the abundances from the coronal to
photospheric values in the impulsive phase of the flares indicates the
injection of fresh unfractionated material from the lower solar atmosphere to
the corona due to chromospheric evaporation. However, explaining the quick
recovery of the abundances from the photospheric to coronal values in the decay
phase of the flare is challenging.Comment: Accepted for publication in 'Solar Physics
Protoplanetary disks around young stellar and substellar objects in the Orionis cluster
Understanding the evolution and dissipation of protoplanetary disks are
crucial in star and planet formation studies. We report the protoplanetary disk
population in the nearby young Orionis cluster (d408 pc;
age1.8 Myr) and analyse the disk properties such as dependence on stellar
mass and disk evolution. We utilise the comprehensive census of 170
spectroscopic members of the region refined using astrometry from Gaia DR3 for
a wide mass range of 19-0.004 M. Using the near infrared (2MASS)
and mid infrared (WISE) photometry we classify the sources based on the
spectral index into class I, class II, flat spectrum and class III young
stellar objects. The frequency of sources hosting a disk with stellar mass 2
M in this region is 417% which is consistent with the disk
fraction estimated in previous studies. We see that there is no significant
dependence of disk fraction on stellar mass among T Tauri stars (2
M), but we propose rapid disk depletion around higher mass stars (2
M). Furthermore we find the lowest mass of a disk bearing object to be
20 M and the pronounced disk fraction among the brown
dwarf population hints at the formation scenario that brown dwarfs form similar
to low-mass stars.Comment: Accepted for publication in The Journal of Astrophysics and
Astronomy. 17 pages, 6 figures, 2 table
Maintained physical activity and physiotherapy in the management of distal upper limb pain – a protocol for a randomised controlled trial (the arm pain trial)
<b>Background</b><p></p>
Distal upper limb pain (pain affecting the elbow, forearm, wrist, or hand) can be non-specific, or can arise from specific musculoskeletal disorders. It is clinically important and costly, the best approach to clinical management is unclear. Physiotherapy is the standard treatment and, while awaiting treatment, advice is often given to rest and avoid strenuous activities, but there is no evidence base to support these strategies. This paper describes the protocol of a randomised controlled trial to determine, among patients awaiting physiotherapy for distal arm pain, (a) whether advice to remain active and maintain usual activities results in a long-term reduction in arm pain and disability, compared with advice to rest; and (b) whether immediate physiotherapy results in a long-term reduction in arm pain and disability, compared with physiotherapy delivered after a seven week waiting list period.<p></p>
<b>Methods/Design</b><p></p>
Between January 2012 and January 2014, new referrals to 14 out-patient physiotherapy departments were screened for potential eligibility. Eligible and consenting patients were randomly allocated to one of the following three groups in equal numbers: 1) advice to remain active, 2) advice to rest, 3) immediate physiotherapy. Patients were and followed up at 6, 13, and 26 weeks post-randomisation by self-complete postal questionnaire and, at six weeks, patients who had not received physiotherapy were offered it at this time. The primary outcome is the proportion of patients free of disability at 26 weeks, as determined by the modified DASH (Disabilities of the Arm, Shoulder and Hand) questionnaire.<p></p>
We hypothesise (a) that advice to maintain usual activities while awaiting physiotherapy will be superior than advice to rest the arm; and (b) that fast-track physiotherapy will be superior to normal (waiting list) physiotherapy. These hypotheses will be examined using an intention-to-treat analysis.<p></p>
<b>Discussion</b><p></p>
Results from this trial will contribute to the evidence base underpinning the clinical management of patients with distal upper limb pain, and in particular, will provide guidance on whether they should be advised to rest the arm or remain active within the limits imposed by their symptoms
Paget's disease of the skull causing hyperprolactinemia and erectile dysfunction: a case report
<p>Abstract</p> <p>Introduction</p> <p>Hyperprolactinemia is an uncommon cause of erectile dysfunction in men. Paget's disease of the skull is a relatively common disease. This case proposes a rare example of a causative link between the two and how treatment of the Paget's disease with bisphosphonates helped the patient regain erectile function.</p> <p>Case presentation</p> <p>A 67-year-old man with Paget's disease of the skull presented with prostatitis, erectile dysfunction, and hyperprolactinemia. Radio-isotope scanning showed increased vascularity around the sphenoid bone. Treatment with intravenous bisphosphonates improved the active Paget's disease as indicated by declining alkaline phosphatase levels and the patient's erectile function while serum prolactin levels became normal and serum testosterone levels remained unchanged.</p> <p>Conclusion</p> <p>It is possible that hyperprolactinemia is unrecognised in other patients with Paget's disease of the skull. Normalizing elevated prolactin levels by using bisphosphonates in treating Paget's disease appears to be more appropriate than traditional treatment for hyperprolactinemia.</p
Generalized Ricci Curvature Bounds for Three Dimensional Contact Subriemannian manifolds
Measure contraction property is one of the possible generalizations of Ricci
curvature bound to more general metric measure spaces. In this paper, we
discover sufficient conditions for a three dimensional contact subriemannian
manifold to satisfy this property.Comment: 49 page
Do acute elevations of serum creatinine in primary care engender an increased mortality risk?
Background: The significant impact Acute Kidney Injury (AKI) has on patient morbidity and mortality emphasizes the need for early recognition and effective treatment. AKI presenting to or occurring during hospitalisation has been widely studied but little is known about the incidence and outcomes of patients experiencing acute elevations in serum creatinine in the primary care setting where people are not subsequently admitted to hospital. The aim of this study was to define this incidence and explore its impact on mortality. Methods: The study cohort was identified by using hospital data bases over a six month period. Inclusion criteria: People with a serum creatinine request during the study period, 18 or over and not on renal replacement therapy. The patients were stratified by a rise in serum creatinine corresponding to the Acute Kidney Injury Network (AKIN) criteria for comparison purposes. Descriptive and survival data were then analysed. Ethical approval was granted from National Research Ethics Service (NRES) Committee South East Coast and from the National Information Governance Board. Results: The total study population was 61,432. 57,300 subjects with ‘no AKI’, mean age 64.The number (mean age) of acute serum creatinine rises overall were, ‘AKI 1’ 3,798 (72), ‘AKI 2’ 232 (73), and ‘AKI 3’ 102 (68) which equates to an overall incidence of 14,192 pmp/year (adult). Unadjusted 30 day survival was 99.9% in subjects with ‘no AKI’, compared to 98.6%, 90.1% and 82.3% in those with ‘AKI 1’, ‘AKI 2’ and ‘AKI 3’ respectively. After multivariable analysis adjusting for age, gender, baseline kidney function and co-morbidity the odds ratio of 30 day mortality was 5.3 (95% CI 3.6, 7.7), 36.8 (95% CI 21.6, 62.7) and 123 (95% CI 64.8, 235) respectively, compared to those without acute serum creatinine rises as defined. Conclusions: People who develop acute elevations of serum creatinine in primary care without being admitted to hospital have significantly worse outcomes than those with stable kidney function
What is the real impact of acute kidney injury?
Background: Acute kidney injury (AKI) is a common clinical problem. Studies have documented the incidence of AKI in a variety of populations but to date we do not believe the real incidence of AKI has been accurately documented in a district general hospital setting. The aim here was to describe the detected incidence of AKI in a typical general hospital setting in an unselected population, and describe associated short and long-term outcomes. Methods: A retrospective observational database study from secondary care in East Kent (adult catchment population of 582,300). All adult patients (18 years or over) admitted between 1st February 2009 and 31st July 2009, were included. Patients receiving chronic renal replacement therapy (RRT), maternity and day case admissions were excluded. AKI was defined by the acute kidney injury network (AKIN) criteria. A time dependent risk analysis with logistic regression and Cox regression was used for the analysis of in-hospital mortality and survival. Results: The incidence of AKI in the 6 month period was 15,325 pmp/yr (adults) (69% AKIN1, 18% AKIN2 and 13% AKIN3). In-hospital mortality, length of stay and ITU utilisation all increased with severity of AKI. Patients with AKI had an increase in care on discharge and an increase in hospital readmission within 30 days. Conclusions: This data comes closer to the real incidence and outcomes of AKI managed in-hospital than any study published in the literature to date. Fifteen percent of all admissions sustained an episode of AKI with increased subsequent short and long term morbidity and mortality, even in those with AKIN1. This confers an increased burden and cost to the healthcare economy, which can now be quantified. These results will furnish a baseline for quality improvement projects aimed at early identification, improved management, and where possible prevention, of AKI
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