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Biomedical subjects

D Fay

Publications and source records attributed to D Fay.

At least 19 recordsLinked to original sources
PubMed2002

Specific heat and thermal conductivity in the mixed state of MgB2.

The specific heat C and the electronic and phononic thermal conductivities kappa(e) and kappa(ph) are calculated in the mixed state for magnetic fields H near H(c2), including the effects of supercurrent flow and Andreev scattering. The resulting function C(H) is nearly linear while kappa(e)(H) exhibits an upward curvature near H(c2). The slopes decrease with impurity scattering which improves the agreement with the data on MgB2. The ratio of phonon relaxation times tau(n)/tau(s)=g(omega(0),H) for phonon energy omega(0) is smeared out around omega(0)=2Delta and tends to one for increasing H. This leads to a rapid reduction of kappa(ph)(H) in MgB2 for relatively small fields due to the rapid suppression of the smaller energy gap.

Journal Article↗
PubMed2002

Effect of spin-orbit scattering on the magnetic and superconducting properties of nearly ferromagnetic metals: application to granular Pt.

We calculate the effect of scattering on the static, exchange enhanced, spin susceptibility and show that, in particular, spin-orbit scattering leads to a reduction of the giant moments and spin glass freezing temperature due to dilute magnetic impurities. The harmful spin fluctuation contribution to the intragrain pairing interaction is strongly reduced opening the way for BCS superconductivity. We are thus able to explain the superconducting and magnetic properties recently observed in granular Pt as being due to scattering effects in single small grains.

Journal Article↗
PubMed1996

Potential costs of flexible sigmoidoscopy-based colorectal cancer screening.

BACKGROUND & AIMS: Increasing evidence shows that periodic screening by flexible sigmoidoscopy with appropriate referral of patients with adenomas to colonoscopy could substantially decrease colorectal cancer mortality rates. Estimates of the complete cost of such screening are needed. The aim of this study was to estimate the annual costs of periodic screening of Americans 50 years and older by flexible sigmoidoscopy with referral of subjects with adenomas to colonoscopy. METHODS: Cost analysis of flexible sigmoidoscopy, followed by colonoscopy as warranted, in U.S. population cohorts reaching age 50 each year from 1995 to 2010 was performed. Total yearly costs of repeat screening and surveillance examinations at American Cancer Society-recommended and other intervals were determined. RESULTS: With screening and surveillance intervals of 3 years, annual costs for the cohort of individuals turning 50 in 1995 would increase to $553 million by 2010. Annual costs for the entire population 50 years of age and older could increase by 2010 to nearly $20 billion. CONCLUSIONS: The cost of flexible sigmoidoscopy-based screening for colorectal cancer could vary as much as threefold depending on the protocol chosen.

Colorectal Neoplasms↗
PubMed1993

Overproduction of Rb protein after the G1/S boundary causes G2 arrest.

The Rb protein is known to exert its activity at decision points in the G1 phase of the cell cycle. To investigate whether it may also play some role(s) at later points in the cell cycle, we used a system of rapid inducible gene amplification to conditionally overexpress Rb protein during G2 phase. A cell line expressing a temperature-sensitive simian virus 40 large T antigen (T-Ag) was stably transfected with plasmids containing the Rb cDNA linked to the simian virus 40 origin of replication: pRB-wt, pRB-fs, and pRB-Dra, carrying wild-type murine Rb cDNA, a frameshift mutation close to the beginning of the Rb coding region, and a single-amino-acid deletion in the E1A/T-Ag binding pocket, respectively. Numerous independent cell lines were isolated at the nonpermissive temperature; cell lines displaying a high level of episomal amplification of an intact Rb expression cassette following shiftdown to the permissive temperature were chosen for further analysis. Plasmid pRB-fs did not express detectable Rb antigen, while pRB-Dra expressed full-length Rb protein. The Dra mutation has previously been shown to abrogate phosphorylation as well as T-Ag binding. Fluorescence-activated cell sorting (FACS) analysis revealed that cultures induced to overexpress either wild-type or Dra mutant Rb proteins were significantly enriched for cells with a G2 DNA content. Cultures that amplified pRB-fs or rearranged pRB-wt and did not express Rb protein had normal cell cycle profiles. Double-label FACS analysis showed that cells overexpressing Rb or Rb-Dra proteins were uniformly accumulating in G2, whereas cells expressing endogenous levels of Rb were found throughout the cell cycle. These results indicate that Rb protein is interacting with some component(s) of the cell cycle-regulatory machinery during G2 phase.

Animals↗
PubMed1992

Mobilization of cognitive resources and the generation effect.

The generation effect refers to the memory advantage of words that have been generated rather than read. Such a read-generate comparison confounds qualitative task differences and raises methodological problems. A revised methodology is proposed circumventing these problems in that the encoding task is held constant and all stimuli have to be generated, but the degree of generativeness (i.e. the amount of cueing) is varied. In Experiment 1, 1, the (refined version of the) generation effect is demonstrated in a within-subjects design; with increasing generation activity left to the subject, free recall performance increases. No effect is obtained for degree of target masking. The same finding is replicated and shown to be independent of self-paced study time when generative activity is manipulated between subjects (Experiment 2) or within subjects (Experiment 3). As all learning trials involve generation, encoding time is controlled statistically, and free recall is used as a measure of memory, this refined generation effect cannot be explained as an artifact of selective attention or elaboration. Rather, generative activity seems to increase the mobilization of cognitive resources. This motivational account is supported by Experiment 4 showing an enhanced generation effect for positive mood.

Adult↗
PubMed1991

Palatability of colonic lavage solution is improved by the addition of artificially sweetened flavored drink mixes.

A frequent complaint of patients asked to drink polyethylene glycol (PEG) colonic lavage solution is the salty flavor. This often results in failure to ingest the entire 4 liters of the solution and compromises bowel cleansing. The purpose of this study was to determine systematically whether the addition of a flavored drink mix sweetened with aspartame to the PEG lavage solution would improve palatability without significantly altering the osmolality of the solution. Eighty-seven (87) staff volunteers participated in a taste test of PEG lavage solutions containing varying amounts of commercially available drink mixes. The solution containing two packages of lemon-flavored KoolAid drink mix sweetened with aspartame was significantly more palatable than the others (p less than 0.005), while osmolality remained within the range specified by the manufacturer of Colyte.

Colon↗
PubMed1990

[Proposal for a polyvalent Simplified Acute Physiology Score of severity in biliary tract surgery].

The SAPS score proposed by Le Gall, was used in 128 patients undergoing biliary surgery between January 1987 and April 1988. The score is based on the laboratory data for the first day. The cumulative post-operative complication rate was established during hospital stay and at one month after discharge. There is a highly significant correlation between the SAPS score, the morbidity and the mean hospital stay. From this study it seems valuable to use this score in surgery reports.

Adult↗
PubMed1986

[Fulminant meningococcemia with intracranial hypertension. External lumbar drainage of cerebrospinal fluid].

An 18-year old girl developed acute fulminating meningococcaemia with meningitis, coma, shock, coagulation disorders and extensive purpura. Measurement of intracranial pressure showed severe intracranial hypertension. After medical treatment of shock and intracranial hypertension had failed, external drainage of the cerebrospinal fluid was performed in the lumbar region, using a 16 G silicone catheter. This controlled the intracranial hypertension; also the state of shock regressed and the patient became fully conscious. The lumbar drainage was maintained for 12 days during which 3180 ml of blood-stained cerebrospinal fluid were evacuated. The fluid was sterilized by antibiotics as early as the 1st day of the disease, but it remained positive for bacterial antigen up to the 9th day. Cure was obtained without neurological sequelae, thanks to the lumber drainage which controlled intracranial hypertension and removed large amounts of microbial toxins.

Acute Disease↗