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Biomedical subjects

Mark Ratner

Publications and source records attributed to Mark Ratner.

18 recordsLinked to original sources
PubMed2006

Stress-biased rearrangements and preyield behavior in glasses.

On the basis of a physical picture of a glass as a mosaic of mesoscopic clusters differing in their yield characteristics, we propose a model for the preyield behavior in glassy materials; the model describes the stress-strain relationship at different strain rates in terms of one reduced variable. A test using experimental data for polycarbonate materials at different rates and temperatures appears favorable for the model. The model may be used to interpolate and extrapolate limited experimental data, and also provides a practical means to assess dynamic heterogeneities within polymeric glasses. When applied at different temperatures, the model gives insight into the dependence of the excitation energies on temperature (glassformer fragility) in the glassy state.

Journal Article↗
PubMed2005

Neuroimaging heats up.

Explore the source record for details and available documents.

Clinical Trials, Phase I as Topic↗
PubMed2003

Interstitial laser coagulation versus transurethral prostate resection for treating benign prostatic obstruction: a randomized trial with 2-year follow-up.

OBJECTIVES: To investigate whether interstitial laser coagulation (ILC) is as effective and as safe as transurethral resection of the prostate (TURP). The treatment of choice for bladder outflow obstruction secondary to benign prostatic hyperplasia is TURP. However, ILC is a less invasive outpatient procedure that may be as effective and safe as TURP. METHODS: In a multicenter randomized trial at six U.S. tertiary care hospitals, we treated 72 men with bladder outflow obstruction secondary to benign prostatic hyperplasia with either TURP (n = 35) or ILC (n = 37). The outcome measures were peak flow rate, postvoid residual urine volume, prostate volume, prostate-specific antigen levels, symptom and quality-of-life indexes, sexual function, and adverse event rates. Measurements were taken at baseline and at 3, 6, 12, and 24 months. RESULTS: At 2 years, the TURP patients had better median peak flow rates, but not significantly so (range 16.5 to 13.9 mL/s, 95% confidence interval for the 2.6 mL/s difference of -0.4 to 7.6). The median scores on the symptom indexes and quality-of-life measures were similarly improved in both groups. Of 37 ILC patients, 6 (16%) were retreated with TURP in the first year. Sexual function declined in the TURP group but remained stable in the ILC group. The adverse event rates were similar, although the events were more serious in the TURP group. CONCLUSIONS: ILC compares respectably with TURP. Given the advantages of an outpatient procedure, similar results in symptom reduction and quality-of-life measures, and less severe adverse effects, ILC can be an acceptable alternative to TURP.

Ambulatory Surgical Procedures↗