Conversion of a glassy antiferromagnetic-insulating phase to an equilibrium ferromagnetic-metallic phase by devitrification and recrystallization in Al substituted Pr(0.5)Ca(0.5)MnO(3)

We show that Pr(0.5)Ca(0.5)MnO(3) with 2.5% Al substitution and La(0.5)Ca(0.5)MnO(3) (LCMO) exhibit qualitatively similar and visibly anomalous M-H curves at low temperature. Magnetic field causes a broad first order but irreversible antiferromagnetic (AF)-insulating (I) to ferromagnetic (FM)-metallic (M) transition in both and gives rise to a soft FM state. However, the low temperature equilibrium state of Pr(0.5)Ca(0.5)Mn(0.975)Al(0.025)O(3) (PCMAO) is FM-M whereas that of LCMO is AF-I. In both systems the respective equilibrium phase coexists with the other phase with contrasting order, which is not in equilibrium, and the cooling field can tune the fractions of the coexisting phases. It is shown earlier that the coexisting FM-M phase behaves like 'magnetic glass' in LCMO. Here we show from specially designed measurement protocols that the AF-I phase of PCMAO has all the characteristics of magnetic glassy states. It devitrifies on heating and also recrystallizes to an equilibrium FM-M phase after annealing. This glass-like AF-I phase also shows a similar intriguing feature observed in FM-M magnetic glassy state of LCMO, that when the starting coexisting fraction of glass is larger, successive annealing results in a larger fraction of the equilibrium phase. This similarity between two manganite systems with contrasting magnetic orders of respective glassy and equilibrium phases points to a possible universality.

Probability, clinical decision making and hypothesis testing

Few clinicians grasp the true concept of probability expressed in the 'P value.' For most, a statistically significant P value is the end of the search for truth. In fact, the opposite is the case. The present paper attempts to put the P value in proper perspective by explaining different types of probabilities, their role in clinical decision making, medical research and hypothesis testing.

An In-vitro Investigation of the Effects of Variable Operating Parameters on Alumina Air-abrasion Cutting Characteristics

Changing air-abrasion operating parameters has an effect on the cutting rate and, ultimately, the depth and shape of cavities produced in Macor (an enamel analogue).

Feasibility of screening for Chlamydia trachomatis in young men attending an emergency department

OBJECTIVE

To determine the feasibility of screening asymptomatic young men for genital Chlamydia trachomatis infection in a suburban emergency department setting.

DESIGN

Prospective observational study.

SETTING

Chase Farm Hospital Emergency Department in Enfield, North London.

PARTICIPANTS

Asymptomatic sexually active men aged 16-24 years.

METHODS

A convenience sample of men aged 16-24 years attending the emergency department was offered urine-based screening for Chlamydia at triage. Verbal consent was obtained and first pass urine specimens were tested using the strand displacement amplification technique. Participants were traced by their preferred method of contact in order to be offered treatment within 2 weeks of attendance at the emergency department.

RESULTS

67 men participated, 64 of whom were tested, 3 returning positive tests. The prevalence of Chlamydia in asymptomatic men attending the emergency department was 4.7%.

CONCLUSION

Urine testing for genital C trachomatis in the emergency department can identify asymptomatic men in the community who may otherwise remain undetected. It is suggested that this is a worthwhile screening test to offer in the emergency department, providing follow-up for treatment can be arranged locally. There is no requirement for increased emergency department input into these patients over and above introducing them to the screening programme.

Depositing graphene films on solid and perforated substrates

Graphene-a monolayer of graphite-has attracted vast interest recently owing to its perfect two-dimensional crystallographic nature and its potential use in a new generation of microelectronic devices. Yet, a deposition method, which results in a large coverage of monolayer thick graphite, is still lacking. By using a chemical mechanical polishing (CMP) method we were able to deposit stress-free graphene on solid and perforated substrates alike, achieving area coverage of hundreds of microns squared.

Phase separation and the effect of quenched disorder in Pr(0.5)Sr(0.5)MnO(3)

The nature of phase separation in Pr(0.5)Sr(0.5)MnO(3) has been probed by linear, as well as nonlinear, magnetic susceptibilities and resistivity measurements across the second order paramagnetic to ferromagnetic transition (T(C)) and first order ferromagnetic to antiferromagnetic transition (T(N)). We found that the ferromagnetic (metallic) clusters, which form at T(C), continuously decrease their size with a decrease in temperature and coexist with non-ferromagnetic (insulating) clusters. These non-ferromagnetic clusters are identified to be antiferromagnetic. It is shown that they do not arise because of the superheating effect of the lower temperature first order transition. This reveals phase coexistence in manganite, around half-doping, encompassing two long-range order transitions. Substitution of quenched disorder (Ga) at Mn-sites promotes antiferromagnetism at the cost of ferromagnetism without adding any magnetic interaction or introducing any significant lattice distortion. Moreover, an increase in disorder decreases the ferromagnetic cluster size and with 7.5% Ga substitution cluster size reduces to the single-domain limit. Resistivity measurements also reveal the phase coexistence identified from the magnetic measurements. It is significant that, an increase in disorder up to 7.5% increases the resistivity of the low temperature antiferromagnetic phase by about four orders.

Role of Ultrasound Therapy in the Healing of Tibial Stress Fractures

BACKGROUND

Stress fracture is the single most common cause for the lost number of manpower days during training. The conventional treatment options begin with rest and cessation of precipitating activity. However the demands of military training provide little tolerance for prolonged periods of rest. In the recent past ultrasound therapy (UST) has been reported to speed up healing of stress fractures.

METHODS

In the present study, a total of 67 cases of stress fracture were studied for the effect of ultrasound therapy on healing time. Study protocol used was double blind placebo controlled.

RESULT

Study results showed that the mean number of days of incapacitation was 25.46 days in the ultrasound treatment group as compared to 39.92 in the placebo group, a difference of 14 days, which was statistically highly significant.

CONCLUSION

The results of the study convincingly prove that ultrasound treatment is effective in cases of stress fracture.

Vitamin D and glucocorticoids differentially modulate chemokine expression in human airway smooth muscle cells

BACKGROUND AND PURPOSE

Chemokines play a critical role in the pathogenesis of asthma and facilitate the recruitment of inflammatory cells in the airways. Evidence now suggests that airway smooth muscle (ASM) may serve as a source of chemokines in inflamed airways. Although vitamin D has potent anti-inflammatory properties in vitro in some cell types, its effects on ASM cells remain unclear. Here, we investigated whether 1alpha, 25-dihydroxy vitamin D3 (calcitriol) modulated chemokine production in ASM.

EXPERIMENTAL APPROACH

Human ASM cell cultures were derived from tracheal samples taken during surgery. ASM cells were treated with tumour necrosis factor alpha (TNFalpha) and/or interferon gamma (IFNgamma) for 24 h in the presence of calcitriol and/or the glucocorticoid fluticasone added 2 h before. RANTES (regulated upon activation, normal T-cell expressed and secreted), interferon-inducible protein 10 (IP-10) and fractalkine (FKN) levels in cell supernatants were measured by ELISA.

KEY RESULTS

In TNFalpha-treated cells, calcitriol inhibited RANTES and IP-10 secretion in a concentration-dependent manner. FKN levels were negligible. In TNFalpha/IFNgamma-treated cells, whereas fluticasone or calcitriol alone partially inhibited RANTES secretion (by 38 and 20%, respectively), the combination of both drugs additively inhibited RANTES secretion (by 60%). No effect was observed on IP-10 secretion. Whereas fluticasone enhanced FKN secretion (by 50%), calcitriol significantly decreased FKN levels (by 50%). Interestingly, calcitriol blocked the stimulatory effect of fluticasone on FKN secretion, which was inhibited by 60% with the combination of calcitriol and fluticasone.

CONCLUSIONS AND IMPLICATIONS

These findings suggest that vitamin D uniquely modulates human ASM expression of chemokines and may exert some beneficial effects in the treatment of steroid-resistant patients with asthma.

Analysis of T-cell proliferation and cytokine secretion in the individuals exposed to arsenic

Over six million people in nine districts of West Bengal, India are exposed to very high levels of arsenic primarily through their drinking water. More than 300,000 people showed arsenic-induced skin lesions in these districts. This is regarded as the greatest arsenic calamity in the world. Chronic arsenicosis causes varied dermatological signs ranging from pigmentation changes, hyperkeratosis to non-melanocytic cancer of skin, and also malignancies in different internal organs. Higher incidences of opportunistic infections are found in the arsenic-exposed individuals, indicating that their immune systems may be impaired somehow. We have thus investigated the effect of arsenic on T-cell proliferation and cytokine secretion in 20 individuals with arsenic-induced skin lesions and compared the results with 18 arsenic-unexposed individuals. A marked dose-dependent suppression of Concanavalin A (Con A) induced T-cell proliferation was observed in the arsenic-exposed individuals compared with the unexposed ( P < 0.001) individuals. This correlated with a significant decrease in the levels of secreted cytokines by the T cells (TNF-α, IFN-γ, IL2, IL10, IL5, and IL4) in the exposed individuals ( P < 0.001). Thus it can be inferred that arsenic exposure can cause immunosuppression in humans.

Adrenalectomy potentiates the anti-inflammatory activity of a calcium channel blocker

Calcium movement is important in the activation of inflammatory cells. Prior studies have shown that calcium channel blockers (CCBs) inhibit carrageenan-induced paw edema in rats by acting at pituitary and hypothalamic levels. Here we evaluated the role of calcium channel blockers and their regulation via the hypothalamus-pituitary-adrenal (HPA) axis in acute and chronic models of rat paw inflammation, using both carrageenan (acute) and formalin (chronic) as inflammation inducers. Adrenalectomized (ADX) and intact Sprague Dawley rats (n = 4 per group) weighing 150-250 each were treated with an intraperitoneal injection of nifedipine (400 microg/kg) or vehicle. Edema was assessed plethysmometrically by evaluating paw volume changes. The results show a significant contradiction between acute and chronic inflammation data. In intact animals, nifedipine demonstrated a significant anti-inflammatory effect in the acute inflammatory model but not in the chronic model. In adrenal-ectomized animals, the anti-inflammatory effect of nifedipine was significantly enhanced both in acute and chronic models. We conclude that adrenalectomy plays a significant role in modulating the inflammatory pathway in the presence of calcium channel blockers.

Hydatid cyst of mediastinum

We report a case of hydatid cyst of the mediastinum in a 32-year-old female patient who was admitted with chest pain. CT scan reported posterior mediastinal mass towards the right side. Surgical exploration revealed a loculated cyst in posterior mediastinum on the right side, adherent to the overlying lung and underlying bone. Posterolateral thoracotomy was performed for cyst aspiration and excision. The patient was discharged on albendazole.