Second magnetization peak, rhombic-to-square Bragg vortex glass transition, and intersecting magnetic hysteresis curves in overdoped BaFe2(As1-xPx)2 single crystals.

The second magnetization peak (SMP) in the fourfold symmetric superconducting single crystals (such as iron pnictides and tetragonal cuprates) has been attributed to the rhombic-to-square transition (RST) of the quasi-ordered vortex solid (the Bragg vortex glass, BVG). This represents an alternative to the pinning-induced BVG disordering as the actual SMP mechanism. The analysis of the magnetic response of BaFe2(As1-xPx)2 specimens presented here shows that the SMP is not generated by the RST. However, the latter can affect the pinning-dependent SMP onset field if this is close to the (intrinsic) RST line, through the occurrence of a "shoulder" on the magnetic hysteresis curves m(H), and a maximum in the temperature variation of the DC critical current density. These features disappear in AC conditions, where the vortex system is dynamically ordered in the RST domain, emphasizing the essential role of vortex dislocations for an efficient accommodation of the vortex system to the pinning landscape and the SMP development. The m(H) shoulder is associated with a precipitous pinning-induced proliferation of dislocations at the RST, where the BVG elastic "squash" modulus softens. The DC magnetization relaxation indicates that the pinning-induced vortex system disordering continues above the RST domain, as the basic SMP mechanism.

Pain and disability in a group of Chinese elderly out-patients in Hong Kong.

OBJECTIVE: To investigate the relationship between musculoskeletal pain and disability among a group of geriatric out-patients. DESIGN: Consecutive case series. SETTING: Regional hospital, Hong Kong. PARTICIPANTS: Attendees at a geriatric specialist out-patient clinic from October 2002 to February 2003. MAIN OUTCOME MEASURES: Pain duration, location, intensity, and frequency; use of analgesics; ability to identify the cause of pain; disability (Barthel index) and Lawton Instrumental Activities of Daily Living scale score; depressive symptoms (Geriatric Depression Scale score); and self-reported sleep quality. RESULTS: Of the 749 respondents, 461 (61.5%) had experienced pain in the previous 2 weeks. Among these patients, 51.3% had received a pain-relieving drug. Compared with men, women reported a higher pain intensity (5.87 versus 5.26; P=0.001), had a lower Barthel index (96.0 versus 97.9; P=0.005), and had a lower score on the Lawton Instrumental Activities of Daily Living scale (42.19 versus 44.52; P=0.008). Multivariate logistic regression showed that the presence of pain was associated with female sex (odds ratio=2.25), poor self-rated health (0.69), and depression (1.54). CONCLUSION: Pain is a common problem among the elderly population, but it is not associated with physical disability, and only half of the patients received analgesics. The study provides information for health care workers to develop strategies to better assess and manage pain problems among elderly people.

A study of postural hypotension in a Chinese elderly outpatient population: are there really associated risk factors?

Postural hypotension is reported to be a common finding in elderly patients with prevalence rates from 10% to 30% having been reported. Proposed risk factors for the development of postural hypotension in the elderly include a number of medical conditions and medications. However, little is known about Chinses populations. From July 1995 through November 1995, we conducted a cross-sectional study on a group of 400 elderly patients (>65 years) in a geriatric outpatient department. Nearly 23% experienced a drop of 20 mmHg or more in systolic blood pressure on going from a supine to standing position. The fall did not correlate well with known risk factors such as use of anti-hypertensive drugs, hypnotics, diabetics mellitus, parkinsonism, and history of a fall. No significant factors were found to be associated with postural hypotension. Our data suggest that the change is idiopathic and does not result in any significant clinical outcome such as falls, syncope, and dizziness.