Observing emergent hydrodynamics in a long-range quantum magnet.

Identifying universal properties of nonequilibrium quantum states is a major challenge in modern physics. A fascinating prediction is that classical hydrodynamics emerges universally in the evolution of any interacting quantum system. We experimentally probed the quantum dynamics of 51 individually controlled ions, realizing a long-range interacting spin chain. By measuring space-time-resolved correlation functions in an infinite temperature state, we observed a whole family of hydrodynamic universality classes, ranging from normal diffusion to anomalous superdiffusion, that are described by Lévy flights. We extracted the transport coefficients of the hydrodynamic theory, reflecting the microscopic properties of the system. Our observations demonstrate the potential for engineered quantum systems to provide key insights into universal properties of nonequilibrium states of quantum matter.

Author Correction: Self-verifying variational quantum simulation of lattice models.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Self-verifying variational quantum simulation of lattice models.

Hybrid classical-quantum algorithms aim to variationally solve optimization problems using a feedback loop between a classical computer and a quantum co-processor, while benefiting from quantum resources. Here we present experiments that demonstrate self-verifying, hybrid, variational quantum simulation of lattice models in condensed matter and high-energy physics. In contrast to analogue quantum simulation, this approach forgoes the requirement of realizing the targeted Hamiltonian directly in the laboratory, thus enabling the study of a wide variety of previously intractable target models. We focus on the lattice Schwinger model, a gauge theory of one-dimensional quantum electrodynamics. Our quantum co-processor is a programmable, trapped-ion analogue quantum simulator with up to 20 qubits, capable of generating families of entangled trial states respecting the symmetries of the target Hamiltonian. We determine ground states, energy gaps and additionally, by measuring variances of the Schwinger Hamiltonian, we provide algorithmic errors for the energies, thus taking a step towards verifying quantum simulation.

OSCE as a Summative Assessment Tool for Undergraduate Students of Surgery-Our Experience.

Traditional examination has inherent deficiencies. Objective Structured Clinical Examination (OSCE) is considered as a method of assessment that may overcome many such deficits. OSCE is being increasingly used worldwide in various medical specialities for formative and summative assessment. Although it is being used in various disciplines in our country as well, its use in the stream of general surgery is scarce. We report our experience of assessment of undergraduate students appearing in their pre-professional examination in the subject of general surgery by conducting OSCE. In our experience, OSCE was considered a better assessment tool as compared to the traditional method of examination by both faculty and students and is acceptable to students and faculty alike. Conducting OSCE is feasible for assessment of students of general surgery.

Acceptability and feasibility of mini-clinical evaluation exercise as a formative assessment tool for workplace-based assessment for surgical postgraduate students.

BACKGROUND: Despite an increasing emphasis on workplace-based assessment (WPBA) during medical training, the existing assessment system largely relies on summative assessment while formative assessment is less valued. Various tools have been described for WPBA, mini-clinical evaluation exercise (mini-CEX) being one of them. Mini-CEX is well accepted in Western countries, however, reports of its use in India are scarce. We conducted this study to assess acceptability and feasibility of mini-CEX as a formative assessment tool for WPBA of surgical postgraduate students in an Indian setting. METHODS: Faculty members and 2nd year surgical residents were sensitized toward mini-CEX and requisite numbers of exercises were conducted. The difficulties during conduction of these exercises were identified, recorded, and appropriate measures were taken to address them. At the conclusion, the opinion of residents and faculty members regarding their experience with mini-CEX was taken using a questionnaire. The results were analyzed using simple statistical tools. RESULTS: Nine faculty members out of 11 approached participated in the study (81.8%). All 16 2nd year postgraduate surgical residents participated (100%). Sixty mini-CEX were conducted over 7 months. Each resident underwent 3-5 encounters. The mean time taken by the assessor for observation was 12.3 min (8-30 min) while the mean feedback time was 4.2 min (3-10 min). The faculty reported good overall satisfaction with mini-CEX and found it acceptable as a formative assessment tool. Three faculty members (33.3%) reported mini-CEX as more time-consuming while 2 (22.2%) found it difficult to carry the exercises often. All residents accepted mini-CEX and most of them reported good to high satisfaction with the exercises conducted. CONCLUSIONS: Mini-CEX is well accepted by residents and faculty as a formative assessment tool. It is feasible to utilize mini-CEX for WPBA of postgraduate students of surgery.

Brahmi for the better? New findings challenging cognition and anti-anxiety effects of Brahmi (Bacopa monniera) in healthy adults.

RATIONALE: A number of studies have indicated positive effects of long-term administration (3 months) of Bacopa monniera (Brahmi) on various cognitive functions especially memory and anxiety. However, inconsistent results in literature may be linked to various methodological issues. OBJECTIVE: The present study aimed to test the chronic effects (12 weeks) of 450 mg of a B. monniera (Brahmi) extract on learning and memory, information processing and anxiety in healthy adult Indian population. METHODS: The study design was a randomised, double-blind, placebo-controlled parallel design. Participants comprised of 72 healthy urban adults, both men and women, in the age range of 35-60 years who were educated and English speaking with basic knowledge of computers from Bangalore. The outcome measures included verbal learning and memory, inspection time, attention and interference. State and trait anxiety were additional outcome variables. RESULTS: In the present study, there were no significant differences between the two groups on any of the cognitive measures. However, there was a trend for lower state anxiety in the B. monniera (Brahmi) group as compared to placebo group. CONCLUSIONS: The current study attempted to determine the chronic effects of single daily dose of 450 mg of Brahmi extract on cognitive performance and anxiety in healthy adults. The results of the current study are not in agreement with findings of some of the earlier studies which have found improvement both on cognitive parameters and a reduction of anxiety scores.

Acute rhabdomyolysis and renal failure in HIV-infected patients: risk factors, presentation, and pathophysiology.

Rhabdomyolysis is a common cause of acute renal failure and may be related to a variety of predisposing factors. This entity has been increasingly recognized in HIV-infected individuals and is an important cause of morbidity and mortality. We present a series of seven HIV-positive patients admitted with rhabdomyolysis over a 5-year period; three developed acute renal failure. Infections and substance abuse were the most common risk factors identified; an average of three predisposing factors was present in each case. All patients showed resolution of creatinine phosphokinase (CPK) elevation and serum creatinine returned to the normal range in the three patients who developed renal insufficiency; however, all patients required prolonged hospitalization and one patient died of sepsis. The pathophysiological mechanisms of muscle injury in our patients are reviewed and their bearing on prognosis discussed. It is concluded that clinicians should have a high index of suspicion for the development of rhabdomyolysis in HIV-infected patients with a combination of noncompliance with medical therapy and/or substance abuse and acute infection. With comprehensive supportive care, the prognosis of acute rhabdomyolysis in this population may be reasonably good.

On the kinetics of voltage formation in purple membranes of Halobacterium salinarium.

The kinetics of the bacteriorhodopsin photocycle, measured by voltage changes in a closed membrane system using the direct electrometrical method (DEM) of Drachev, L.A., Jasaitus, A.A., Kaulen, A.D., Kondrashin, A.A., Liberman, E.A., Nemecek, I.B., Ostroumov, S.A., Semenov, Yu, A. & Skulachev, V.P. (1974) Nature 249, 321-324 are sixfold slower than the kinetics obtained in optical studies with suspensions of purple membrane patches. In this study, we have investigated the reasons for this discrepancy. In the presence of the uncouplers carbonyl cyanide m-chlorophenylhydrazone or valinomycin, the rates in the DEM system are similar to the rates in suspensions of purple membrane. Two alternative explanations for the effects of uncouplers were evaluated: (a) the 'back-pressure' of the Deltamicro;H+ slows the kinetic steps leading to its formation, and (b) the apparent difference between the two systems is due to slow major electrogenic events that produce little or no change in optical absorbance. In the latter case, the uncouplers would decrease the RC time constant for membrane capacitance leading to a quicker discharge of voltage and concomitant decrease in photocycle turnover time. The experimental results show that the primary cause for the slower kinetics of voltage changes in the DEM system is thermodynamic back-pressure as described by Westerhoff, H.V. & Dancshazy, Z. (1984) Trends Biochem. Sci. 9, 112-117.

Regulation of the bacteriorhodopsin photocycle and proton pumping in whole cells of Halobacterium salinarium.

Single-turnover kinetics of the bacteriorhodopsin photocycle and proton-pumping capabilities of whole cells were studied. It was found that the Delta mu (tilde)H+ of the cell had a profound influence on the kinetics and components of the cycle. For example, comparing the photocycle in whole cells to that seen in PM preparations, we found that (1) the single-turnover time of the cycle was increased approximately 10-fold, (2) the mole fraction of M-fast (at high actinic light) decreased from 50 to 20%, and (3) the time constant for M-slow increased significantly. The level of Delta mu(tilde)H+ was dependent on respiration, ATP formation and breakdown, and the magnitude of a pre-existing K+ diffusion gradient. The size of the Delta mu(tilde)H+ could be manipulated by additions of HCN, nigericin, and DCCD (N,N'-dicyclohexylcarbodamide). At higher levels of Delta mu(tilde)H+, further changes in the photocycle were seen. (4) Two slower components of M-decay appeared as major components. (5) The apparent conversion of the M-fast to the O intermediate disappeared. (6) A partial reversal of an early photocycle step occurred. The photocycle of intact cells could be changed to that seen in purple membrane suspensions by the energy-uncoupler CCCP or by lysis of the cells. In fresh whole cells, light-induced proton pumping was not seen until the K+ diffusion potential was dissipated and proton accumulation facilitated by use of a K+-H+ exchanger (nigericin), respiration was inhibited by HCN, and ATP synthesis and breakdown were inhibited by DCCD. In stored cells, the pre-existing K+ diffusion gradient was diminished through slow diffusion, and only DCCD and HCN were required to elicit proton extrusion.

Importance of specific native lipids in controlling the photocycle of bacteriorhodopsin.

Brief treatment of purple membrane (PM) with dilute detergent can cause major disruption of the BR photocycle without disrupting the trimer structure of BR [Mukhopadhyay et al. (1996) Biochemistry 35, 9245-9252]. Normal photocyle behavior can be recovered by incubating the damaged membranes with a total extract of the five types of native lipids present in PM. It is shown here that full restoration can also be obtained with combinations of squalene (SQ) and phosphatidyl glycerophosphate (PGP) which act synergistically. The addition of SQ to suboptimal levels of PGP induces complete reconstitution, principally by restoring the characteristics of the fast M intermediate, Mf (as defined in Mukhopadhyay et al. (1996) Biochemistry 35, 9245-9252). The addition of small amounts of PGP to SQ, which alone is ineffective, also induces full reconstituion. At very high levels, full reconstitution can be obtained with PGP alone. These results, in combination with earlier studies which implicate an acidic amino acid residue [Bose et al. (1997) J. Phys. Chem. B 101, 10584-10587], suggest that a crucial interaction between a particular amino acid residue and a SQ-PGP lipid complex may be essential for normal BR photocycle activity.

Lipoprotein lipase deficiency.

A rare case of a 3 month old child with lipoprotein lipase deficiency who presented with bronchopneumonia is reported. After noticing lipaemic serum and lipaemia retinalis, a diagnosis of hyperlipoproteinaemia was considered. Lipoprotein lipase deficiency was confirmed with post heparin lipoprotein lipase enzyme activity estimation.

Pattern of sexually transmitted diseases in Allahabad.

PIP: The distribution of sexually transmitted diseases (STDs) in 1922 consecutive patients of the PG Department of Medicine, MLN Medical College, Allahabad, India, from 1978-1988 is reviewed. 95.3% were male; ages ranged from 4 months-72 years; most were aged 20-29 years old. The STDs found in descending order were chancroid in 33.1%, gonorrhea 21.3%, syphilis 16.7%, genital herpes 13.9%, venereal warts 5.41%, balanoposthitis 3.6%, Donovanosis 3.02%, condyloma accuminata 2.5%, lymphogranuloma venereum 1.46%, and molluscum contagiosum 0.62%. 1.14% were mixed infections. In women secondary syphilis was the most common infection. Men almost always reported prostitutes as the source of their illness, while women always cited spouses: 86% of husbands of infected married women had evidence of STDs.^ieng

Polymorphonuclear leukocyte functions in patients with acute rheumatic fever and rheumatic heart disease.

Polymorphonuclear (PMN) cell function was assessed in 30 children with active rheumatic fever (ARF) (Group I), 30 cases with active rheumatic heart disease (RHD) (Group II), 28 cases of ARF and RHD in remission (Group III) and 34 adults with quiescent RHD along with their age matched controls. All the groups showed normal spontaneous and chemotactic movement. Phagocytosis of yeast particles was significantly reduced in groups II (P less than 0.0005), III (P less than 0.025) and IV (P less than 0.005). The opsonic activity of disease sera was low in all 4 groups (P less than 0.0005). The intracellular metabolic activity was moderately elevated in Group III. Phagocytosis and opsonic activity were thus persistently low in all the groups including the remission and quiescent group.