3,072 research outputs found
Discovery of disc precession in the M31 dipping X-ray binary Bo 158
We present results from three XMM-Newton observations of the M31 low mass
X-ray binary XMMU J004314.4+410726.3 (Bo 158), spaced over 3 days in 2004,
July. Bo 158 was the first dipping LMXB to be discovered in M31. Periodic
intensity dips were previously seen to occur on a 2.78-hr period, due to
absorption in material that is raised out of the plane of the accretion disc.
The report of these observations stated that the dip depth was anti-correlated
with source intensity. However, our new observations do not favour a strict
intensity dependance, but rather suggest that the dip variation is due to
precession of the accretion disc. This is to be expected in LMXBs with a mass
ratio <~ 0.3 (period <~ 4 hr), as the disc reaches the 3:1 resonance with the
binary companion, causing elongation and precession of the disc. A smoothed
particle hydrodynamics simulation of the disc in this system shows retrograde
rotation of a disc warp on a period of ~11 P_orb, and prograde disc precession
on a period of ~29 P_orb. This is consistent with the observed variation in the
depth of the dips. We find that the dipping behaviour is most likely to be
modified by the disc precession, hence we predict that the dipping behaviour
repeats on a 81+/-3 hr cycle.Comment: 9 pages, 6 figures, accepted for publication by MNRAS, changed
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'But what is the reason why you know such things?' Question and response patterns in the LADO interview
This study uses the tools of Conversation Analysis (CA) to investigate problems that occur in LADO (Language Analysis for the Determination of Origin) interviews. We analysed five recorded interviews with female asylum seekers, focussing on question and response pairs. Several problems were identified, associated with directives, echo questions, and challenges. The study also looked at how repair is initiated and carried out. Directives were frequently issued as part of multiple questions from the interviewer, alongside additional questions or modifiers. Interviewees typically provided an answer to the most specific and/or most recent question rather than fulfilling the directive itself. Directives were also used to elicit language samples, and it was found that including a clear topic for talk was the most effective way of accomplishing this goal. Echo questions were predominantly used for requesting confirmation, and were occasionally interpreted as performing this function even where there was evidence that interviewers were using echo questions to prompt for more information or to initiate repair. Challenges contributed to a hostile atmosphere in interviews. Similarly, repair prefaced by initial but was found to be potentially hostile in some instances. Various modes of accomplishing repair were also investigated, but their effectiveness was variable. In assessing the set of question and response pairs in the recordings, we make a number of practical recommendations for improving interview practice in LADO
Duct Excision is Still Necessary to Rule out Breast Cancer in Patients Presenting with Spontaneous Bloodstained Nipple Discharge
Introduction. Spontaneous nipple discharge is the third most common reason for presentation to a symptomatic breast clinic. Benign and malignant causes of spontaneous nipple discharge continue to be difficult to distinguish. We analyse our experience of duct excisions for spontaneous nipple discharge to try to identify features that raise suspicion of breast cancer and to identify features indicative of benign disease that would be suitable for nonoperative management. Methods. Details of one hundred and ninety-four patients who underwent duct excision for spontaneous nipple discharge between 1995 and 2005 were analysed. Results. Malignant disease was identified in 11 (5.7%) patients, 4 invasive and 7 insitu, which was 10.2% of those presenting with bloodstained discharge. All patients with malignant disease had bloodstained discharge. Discharge due to malignant disease was more likely to be bloodstained than that due to benign causes (Fisher's exact test, 2-tailed P value = 0.00134). Conclusion. Our findings do not support a policy of conservative management of spontaneous bloodstained nipple discharge. Cases of demonstrable spontaneous bloodstained nipple discharge should undergo duct excision to prevent malignant lesions being missed
The Stroke Data Bank: Design, Methods, and Baseline Characteristics
The National Institute of Neurological and Communicative Disorders and Stroke Initiated the Stroke Data Bank, which is a Multicenter Project to Prospectively Collect Data on the Clinical Course and Sequelae of Stroke. Additional Objectives Were to Provide Information that Would Enable a Standard Diagnostic Clinical Evaluation, to Identify Prognostic Factors, and to Provide Planning Data for Future Studies. a Brief Description of the Structure and Methods Precede the Baseline Characterization of 1,805 Patients Enrolled in the Stroke Data Bank between July 1983 and June 1986. Two Thirds of These Patients Were Admitted within 24 Hours after Stroke Onset. Medical History, Neurologic History, and Hospitalization Summaries Are Presented Separately for the Following Stroke Subtypes: Infarction, Unknown Cause; Embolism from Cardiac Source; Infarction Due to Atherosclerosis; Lacune; Parenchy-Matous or Intracerebral Hemorrhage; Subarachnoid Hemorrhage; and Other. the Utility and Limitations of These Data Are Discussed. © 1988 American Heart Association, Inc
Determinants of Early Recurrence of Cerebral Infarction: The Stroke Data Bank
We Studied 1,273 Patients with Ischemic Cerebral Infarction Who Were Entered into the Stroke Data Bank, a Prospective, Observational Study Involving Four University Hospitals and the Biometry and Field Studies Branch of the National Institute of Neurological Disorders and Stroke. Forty Patients Had Non-Iatrogenic Recurrent Stroke within 30 Days after the Index Cerebral Infarction. using Life Tables, the 30-Day Cumulative± SE Risk of Early Recurrence for All Infarctions Was 3.3±0.4%. the Risk of Early Recurrence Was Greatest for Atherothrombotic Infarction (7.9±2.2%, Eight of 113 Patients) and Least for Lacunar Infarction (2.2±1.2%, Eight of 337 Patients). Both Cardioembolic Infarction (4.3±0.9%, 10 of 246 Patients) and Infarction of Undetermined Cause (3.0±0.5%, 14 of 508 Patients) Had Intermediate Risks. History of Hypertension and Diabetes Mellitus, as Well as Diastolic Hypertension and Elevated Blood Sugar Concentration at Admission, Were Associated with Early Recurrence. Logistic Regression Analysis Estimated the Risk of Early Recurrence to Be 8.56% in Those with Coexisting Hypertension and a Glucose Concentration of 300 Mg/dl Versus 0.77% in the Absence of These Two Abnormalities. Early Recurrence Was Associated with Longer Median Duration of Initial Hospital Stay (27 vs.. 14 Days) and a Higher 30-Day Case—fatality Rate (20% vs.. 7.4%). Increased Weakness Scores Were Associated with Early Recurrent Stroke. Identification of the Determinants of Early Recurrent Stroke May Lead to Better Secondary Prevention and May Help Select High-Risk Patients for Further Study. © 1989 American Heart Association, Inc
A new multi-center approach to the exchange-correlation interactions in ab initio tight-binding methods
A new approximate method to calculate exchange-correlation contributions in
the framework of first-principles tight-binding molecular dynamics methods has
been developed. In the proposed scheme on-site (off-site) exchange-correlation
matrix elements are expressed as a one-center (two-center) term plus a {\it
correction} due to the rest of the atoms. The one-center (two-center) term is
evaluated directly, while the {\it correction} is calculated using a variation
of the Sankey-Niklewski \cite{Sankey89} approach generalized for arbitrary
atomic-like basis sets. The proposed scheme for exchange-correlation part
permits the accurate and computationally efficient calculation of corresponding
tight-binding matrices and atomic forces for complex systems. We calculate bulk
properties of selected transition (W,Pd), noble (Au) or simple (Al) metals, a
semiconductor (Si) and the transition metal oxide Ti with the new method
to demonstrate its flexibility and good accuracy.Comment: 17 pages, 5 figure
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