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Biomedical subjects

M Greenblatt

Publications and source records attributed to M Greenblatt.

At least 19 recordsLinked to original sources
PubMed2006

Onset of motion and dynamic reordering of a vortex lattice.

Time resolved transport measurements on a driven vortex lattice in an undoped 2H-NbSe2 crystal show that the response to a current pulse is governed by healing of defects as the lattice evolves from a stationary to a moving steady state and that the response time reflects the degree of order in the initial vortex state. We find that stationary field cooled vortex lattices become more ordered with decreasing temperature and identify a temperature below which a qualitative change in the response signals the disappearance of topological defects.

Journal Article↗
PubMed2004

Observation of the vortex lattice spinodal in NbSe2.

Metastable superheated and supercooled vortex states in NbSe2 crystals were probed with fast transport measurements over a wide range of field and temperature. The limit of metastability of the superheated vortex lattice defines a line in the phase diagram that lies below the superconducting transition and is clearly separated from it. This line is identified as the vortex lattice spinodal, and is in good agreement with recent theoretical predictions by Li and Rosenstein [Phys. Rev. B 65, 220504 (2002)]; cond-mat/0305258]. By contrast, no limit of metastability is observed for the supercooled disordered state.

Journal Article↗
PubMed2001

Depinning of a metastable disordered vortex lattice.

We report on experiments investigating the depinning dynamics of a strongly pinned vortex lattice in 2H-NbSe2. We find that the depinning process starts at currents that are well below the critical current of the entire lattice and that it is governed by the formation of contiguous channels of mobile vortices connecting the sample edges. We obtain the formation time of the first channel by monitoring the delayed voltage response to a driving current step and by measuring the ramping rate dependence of the critical current. The subsequent increase in the number of moving vortices is determined from the temporal evolution of the voltage response and the critical current.

Journal Article↗
PubMed2000

Smith et al. reply

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Journal Article↗
PubMed2000

Equilibration and dynamic phase transitions of a driven vortex lattice.

We report on the observation of two types of current driven transitions in metastable vortex lattices. The metastable states, which are missed in usual slow transport measurements, are detected with a fast transport technique in the vortex lattice of undoped 2H-NbSe2. The transitions are seen by following the evolution of these states when driven by a current. At low currents we observe an equilibration transition from a metastable to a stable state, followed by a dynamic crystallization transition at high currents.

Journal Article↗
PubMed1997

Database of p53 gene somatic mutations in human tumors and cell lines: updated compilation and future prospects.

In recent years, there has been an exponential increase in the number of p53 mutations identified in human cancers. The p53 mutation database consists of a list of point mutations in thep53 gene of human tumors and cell lines, compiled from the published literature and made available through electronic media. The database is now maintained at the International Agency for Research on Cancer (IARC) and is updated twice a year. The current version contains records on 5091 published mutations and is expected to surpass the 6000 mark in the January 1997 release. The database is available in various formats through the European Bioinformatics Institute (EBI) ftp server at: ftp://ftp.ebi.ac.uk/pub/databases/p53/ or by request from IARC (p53database@iarc.fr) and will be searchable through the SRS system in the near future. This report provides a description of the criteria for inclusion of data and of the current formats, a summary of the relevance ofp53 mutation analysis to clinical and biological questions, and a brief discussion of the prospects for future developments.

Databases, Factual↗
PubMed1996

Somatic point mutations in the p53 gene of human tumors and cell lines: updated compilation.

In 1994 we described a list of approximately 2500 point mutations in the p53 gene of human tumors and cell lines which we had compiled from the published literature and made available electronically through the file server at the EMBL Data Library. This database, updated twice a year, now contains records on 4496 published mutations (July 1995 release) and can be obtained from the EMBL Outstation-the European Bioinformatics Institute (EBI) through the network or on CD-ROM. This report describes the criteria for inclusion of data in this database, a description of the current format and a brief discussion of the current relevance of p53 mutation analysis to clinical and biological questions.

CD-ROM↗
PubMed1993

Life-styles, adaptive strategies, and sexual behaviors of homeless adolescents.

OBJECTIVES: The purpose of this study was to gather information about homeless adolescents, a largely invisible and understudied population. METHODS: Highly trained interviewers conducted structured face-to-face field interviews with 93 homeless adolescents between the ages of 13 and 17 in the Hollywood area of Los Angeles. RESULTS: Seventy-nine percent of the sample had experienced more than one homeless episode in their lifetime, and almost a fourth reported more than ten episodes. Mean length of time homeless was 440 days (median of 201 days). Aggressive and violent behaviors, including stealing, destruction of property, and physical fights, were common. The sample had a high prevalence of several mental disorders, including conduct disorder with aggression, major depression, and alcohol and drug abuse. Almost half had attempted suicide. Nearly all the adolescents were sexually active; about a third had more than ten partners in the previous year. About a third reported trading sex for money, food, or drugs. Although most had basic knowledge of HIV transmission and used some form of birth control, little more than half had used a condom in the most recent sexual encounter, and 18 percent reported sex with intravenous drug users. CONCLUSIONS: Further research on this population is needed, and follow-up contacts in particular are essential in developing appropriate and successful service programs for them.

Adaptation, Psychological↗
PubMed1992

Radioprotection of mice by recombinant rat stem cell factor.

Treatment with recombinant rat stem cell factor (rSCF) protects mice from the lethal effects of irradiation. Mice treated with a single dose of rSCF prior to irradiation of up to 1150 rads [given as a split dose (1 rad = 0.01 Gy)] resulted in > 80% long-term survival, whereas a single injection given after the last dose of irradiation was not radioprotective. The combination of pre- and posttreatment (-20 h, -2 h, and +4 h) with rSCF resulted in 100% survival of otherwise lethally irradiated mice. Using this optimum schedule of rSCF administration, a radioprotective factor of 1.3-1.35 was achieved. The major cause of death in the control animals was massive bacteremia consisting of enteric organisms. The rSCF-treated animals had a much lower frequency of septicemia, due primarily to a rapid hematopoietic recovery of bone marrow function not evident in control animals.

Animals↗