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Biomedical subjects

Sriram Ramaswamy

Publications and source records attributed to Sriram Ramaswamy.

At least 19 recordsLinked to original sources
PubMed2006

Active nematics are intrinsically phase separated.

Two-dimensional nonequilibrium nematic steady states, as found in agitated granular-rod monolayers or films of orientable amoeboid cells, were predicted [Europhys. Lett. 62, 196 (2003)10.1209/epl/i2003-00346-7] to have giant number fluctuations, with the standard deviation proportional to the mean. We show numerically that the steady state of such systems is macroscopically phase separated, yet dominated by fluctuations, as in the Das-Barma model [Phys. Rev. Lett. 85, 1602 (2000)10.1103/PhysRevLett.85.1602]. We suggest experimental tests of our findings in granular and living-cell systems.

Journal Article↗
PubMed2006

Brownian-drag induced particle current in a model colloidal system.

We numerically study the behavior of a collection of overdamped Brownian particles in a channel, in the presence of a flow field applied on similar but slower particles in a wide chamber in contact with the channel. For a suitable range of shear rates, we find that the flow field induces a unidirectional drift in the confined particles, and is stronger for narrower channels. The average drift velocity initially rises with increasing shear rate, then shows saturation for a while, thereafter starts decreasing, in qualitative agreement with recent theoretical studies [Phys. Rev. B 70, 205423 (2004)] based on Brownian drag and "loss of grip." Interestingly, if the sign of the interspecies interaction is reversed, the direction of the induced drift remains the same, but the flow rate at which loss of grip occurs is lower, and the level of fluctuations is higher.

Journal Article↗
PubMed2006

Do current-density nonlinearities cut off the glass transition?

Extended mode-coupling theories for dense fluids predict that nonlinear current-density couplings cut off the singular "ideal glass transition" present in the standard mode-coupling theory where such couplings are ignored. We suggest here that, rather than allowing for activated processes as sometimes supposed, contributions from current-density couplings are always negligible close to a glass transition. We discuss in schematic terms how activated processes can nonetheless cut off the transition by causing the memory function to become linear in correlators at late times.

Journal Article↗
PubMed2006

Risperidone monotherapy for post-traumatic stress disorder related to sexual assault and domestic abuse in women.

Post-traumatic stress disorder is a common, chronic, and often disabling mental illness. Selective serotonin reuptake inhibitors are the usual first-line treatment for post-traumatic stress disorder, but many patients fail to respond adequately. Thus, other treatment options, including the atypical antipsychotics such as risperidone, need to be tested. Women between the ages of 19 and 64 years with post-traumatic stress disorder were enrolled. Symptom severity was rated at baseline using the Treatment Outcomes Post-traumatic Stress Disorder Scale-8, Hamilton Rating Scale for Anxiety, Hamilton Rating Scale for Depression, and Clinician Administered Post-traumatic Stress Disorder Scale. After washout from other psychotropic medications, 20 participants were randomized to either risperidone or placebo. Total score on the Treatment Outcomes Post-traumatic Stress Disorder Scale-8 served as the primary outcome measure. Repeated-measures analysis of variance was followed by Newman-Keuls tests. A significant main effect exists for visits using the Treatment Outcomes Post-traumatic Stress Disorder Scale-8 raw score. For the treatment group, the difference between baseline Treatment Outcomes Post-traumatic Stress Disorder Scale-8 scores and treatment visit scores was significant beginning at visit 6 and continued through visit 11. No significant difference observed between baseline and any treatment visit for the placebo group. The Clinician Administered Post-traumatic Stress Disorder Scale, Hamilton Rating Scale for Anxiety, and Hamilton Rating Scale for Depression data revealed a similar pattern. In this small pilot study, risperidone monotherapy was more effective than placebo in the treatment of post-traumatic stress disorder.

Adult↗
PubMed2006

Behavioral manifestations of sturge-weber syndrome: a case report.

Sturge-Weber syndrome is a neurocutaneous syndrome that manifests with vascular malformations involving the brain, eye, and skin. We report the case of an elderly patient suffering from Sturge-Weber syndrome who presented with episodic "angry" slapping symptoms to a psychiatric facility. A detailed history, physical and mental-state examination, and elaborate neuropsychological, neuroimaging, and laboratory assessment were undertaken. Clinically, the "angry" slapping episodes were diagnosed as complex partial seizures that improved in frequency with an increase in the dose of the antiepileptic medication. We also have attempted to identify the pathophysiology of such behavioral episodes in Sturge-Weber syndrome. This case report underlines the need for detailed laboratory and neuroimaging work-up in the elderly presenting with atypical symptoms. It also emphasizes the need for identification of and differentiation between similar atypical presentations and appropriate management of resources by the medical staff.

Journal Article↗
PubMed2005

Routes to spatiotemporal chaos in the rheology of nematogenic fluids.

With a view to understanding the "rheochaos" observed in recent experiments in a variety of orientable fluids, we study numerically the equations of motion of the spatiotemporal evolution of the traceless symmetric order parameter of a sheared nematogenic fluid. In particular we establish, by decisive numerical tests, that the irregular oscillatory behavior seen in a region of parameter space where the nematic is not stably flow-aligning is in fact spatiotemporal chaos. We outline the dynamical phase diagram of the model and study the route to the chaotic state. We find that spatiotemporal chaos in this system sets in via a regime of spatiotemporal intermittency, with a power-law distribution of the widths of laminar regions, as in H. Chaté and P. Manneville, Phys. Rev. Lett. 58, 112 (1987). Further, the evolution of the histogram of band sizes shows a growing length scale as one moves from the chaotic towards the flow-aligned phase. Finally we suggest possible experiments in which one can observe the intriguing behaviors discussed here.

Journal Article↗
PubMed2005

Electroconvulsive therapy after repair of cerebral aneurysm.

There are cases in the literature describing the use of electroconvulsive therapy (ECT) in patients with intracerebral aneurysms. We report the clinical course of a 60-year-old woman with a history of a recently ruptured intracerebral aneurysm and placement of a ventriculoperitoneal shunt that was successfully treated with ECT for major depressive disorder. Beta blockade with esmolol 20-50 mg was used to maintain her blood pressure, which ranged from 100/63 to 170/94 mm Hg. Propofol was used for anesthesia. There were no vascular complications secondary to the ECT procedure.

Aneurysm, Ruptured↗
PubMed2005

A primary care perspective of posttraumatic stress disorder for the Department of Veterans Affairs.

Posttraumatic stress disorder (PTSD) is a major mental disorder associated with significant morbidity, psychosocial impairment, and disability. The diagnosis of PTSD can be missed in a primary care setting, as patients frequently present with somatic complaints or depression and are often reluctant to discuss their traumatic experiences. As recent studies of veterans returning from the Gulf War and the Iraqi War suggest high rates of PTSD, the U.S. Department of Veterans Affairs (VA) Hospitals are gearing up to face this challenge. It is important to screen these veterans for symptoms of PTSD and make an appropriate referral if required. In this article, we attempt to review PTSD with a special focus on the VA population. In addition to discussing the epidemiology, diagnosis, and treatment options for PTSD, we also suggest screening questions for both combat-related and military sexual trauma-related PTSD.

Journal Article↗
PubMed2005

Ziprasidone therapy for post-traumatic stress disorder.

We describe the cases of 2 men with chronic combat-induced post-traumatic stress disorder (PTSD) who benefited from therapy with ziprasidone. They did not have active psychotic symptoms. Both the patients had a history of inadequate response to previous trials of different psychotropic agents. Ziprasidone was considered because of its broad-spectrum actions on various neurotransmitters. To our knowledge, this is the first published report of the usefulness of ziprasidone in the pharmacotherapy of PTSD, although atypical antipsychotic agents (e.g., olanzapine, quetiapine and risperidone) have been reported to be beneficial in the treatment of this condition.

Antipsychotic Agents↗
PubMed2004

Patient and physician attitudes to using medications with religiously forbidden ingredients.

BACKGROUND: Over 1000 medications contain pork- and/or beef-derived gelatin and stearic acid as inert ingredients. Use of these medications in patients with religious beliefs against consumption of these ingredients might constitute an ethical conflict. OBJECTIVE: To assess patients' and physicians' attitudes about using medications with religiously prohibited ingredients derived from pork and/or beef. METHODS: In this pilot study, 100 patients and 100 physicians completed a survey designed to assess their knowledge and opinion on using medications that might contain inert ingredients derived from animals whose consumption offends followers of certain religions. RESULTS: Of the 100 patients surveyed, most (84%) reported that they were not aware that several medications contained ingredients derived from pork and/or beef. About 63% of the patients wanted their physicians, and 35% of the patients wanted their non-physician healthcare providers (pharmacists, nurses), to inform them when using such medications. Thirteen percent of the patients shared religious reasons for not consuming pork and/or beef products. Approximately 70% of physicians were unaware that several medications contain ingredients that might be against their patients' religion, and most (70%) thought that it was important to inform their patients if such drugs were prescribed. CONCLUSIONS: This pilot study suggests that both patients and physicians think that patients should be informed whenever medications that contain pork- and/or beef-derived products are prescribed. The use of medications with these ingredients is an ethical issue. Informing patients about this issue promotes respect for their religious beliefs and may promote therapeutic alliance; therefore, this might have public health implications and needs further research.

Adult↗
PubMed2004

Rheology of active-particle suspensions.

We study the interplay of activity, order, and flow through a set of coarse-grained equations governing the hydrodynamic velocity, concentration, and stress fields in a suspension of active, energy-dissipating particles. We make several predictions for the rheology of such systems, which can be tested on bacterial suspensions, cell extracts with motors and filaments, or artificial machines in a fluid. The phenomena of cytoplasmic streaming, elastotaxis, and active mechanosensing find natural explanations within our model.

Cytoplasmic Streaming↗
PubMed2004

Spatiotemporal rheochaos in nematic hydrodynamics.

Motivated by recent observations of rheochaos in sheared wormlike micelles, we study the coupled nonlinear partial differential equations for the hydrodynamic velocity and order-parameter fields in a sheared nematogenic fluid. In a suitable parameter range, we find irregular, dynamic shear banding and establish by decisive numerical tests that the chaos we observe in the model is spatiotemporal in nature.

Journal Article↗