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Biomedical subjects

G Crawford

Publications and source records attributed to G Crawford.

At least 19 recordsLinked to original sources

Direct measurements of Ab and Ac using vertex and kaon charge tags at the SLAC detector.

Exploiting the manipulation of the SLAC Linear Collider electron-beam polarization, we present precise direct measurements of the parity-violation parameters A(c) and A(b) in the Z-boson-c-quark and Z-boson-b-quark coupling. Quark-antiquark discrimination is accomplished via a unique algorithm that takes advantage of the precise SLAC Large Detector charge coupled device vertex detector, employing the net charge of displaced vertices as well as the charge of kaons that emanate from those vertices. From the 1996-1998 sample of 400 000 Z decays, produced with an average beam polarization of 73.4%, we find A(c)=0.673+/-0.029(stat)+/-0.023(syst) and A(b)=0.919+/-0.018(stat)+/-0.017(syst).

Journal Article↗

Improved direct measurement of the parity-violation parameter Ab using a mass tag and momentum-weighted track charge.

We present an improved direct measurement of the parity-violation parameter A(b) in the Z boson-b-quark coupling using a self-calibrating track-charge technique applied to a sample enriched in Z-->bb events via the topological reconstruction of the B hadron mass. Manipulation of the Stanford Linear Collider electron-beam polarization permits the measurement of A(b) to be made independently of other Z-pole coupling parameters. From the 1996-1998 sample of 400,000 hadronic Z decays, produced with an average beam polarization of 73.4%, we find A(b)=0.906+/-0.022(stat)+/-0.023(syst).

Journal Article↗

Improved direct measurement of A(b) and A(c) at the Z(0) pole using a lepton tag.

The parity violation parameters A(b) and A(c) of the Zb(b) and Zc(c) couplings have been measured directly, using the polar angle dependence of the polarized cross sections at the Z(0) pole. Bottom and charmed hadrons were tagged via their semileptonic decays. Both the electron and muon analyses take advantage of new multivariate techniques to increase the analyzing power. Based on the 1993-1998 SLD sample of 550,000 Z(0) decays produced with highly polarized electron beams, we measure A(b) = 0.919+/-0.030(stat)+/-0.024(syst), and A(c) = 0.583+/-0.055(stat)+/-0.055(syst).

Journal Article↗

Long-term efficacy and tolerability of rizatriptan wafers in migraine.

CONTEXT: Rizatriptan is a selective 5-HT1B/1D receptor agonist for the acute treatment of migraine. It is available in a unique wafer formulation that dissolves rapidly in the mouth and can be taken without liquids, thereby offering patients a very convenient way to take treatment. OBJECTIVE: To investigate the long-term efficacy of rizatriptan 10-mg and 5-mg wafers in migraineurs. SETTING: 19 headache clinics in 5 countries. PATIENTS: 458 patients diagnosed with migraine according to International Headache Society criteria. DESIGN: 6-month, open-label, extension, which followed a double-blind, placebo-controlled study. INTERVENTIONS: Patients were randomly assigned to 1 of 3 treatments for moderate or severe migraines: rizatriptan 10-mg wafer, rizatriptan 5-mg wafer, or "standard care" (usual migraine treatment -- eg, nonsteroidal anti-inflammatory drugs [NSAIDs], analgesics, other triptans). Patients randomized to rizatriptan were blinded to the dose. MAIN OUTCOME MEASURES: Headache severity (none, mild, moderate, severe) and adverse events were recorded on a diary card. RESULTS: 181 patients treated 3393 attacks with rizatriptan 10-mg wafer, 191 treated 3254 attacks with rizatriptan 5-mg wafer, and 86 treated 1582 attacks with standard care. The median number of treated attacks per patient was 16 for rizatriptan 10-mg wafer, 13 for rizatriptan 5-mg wafer, and 14 for standard care. The median patient on rizatriptan 10-mg wafer reported pain relief at 2 hours (reduction of headache from moderate or severe at baseline to mild or none) in 82% of attacks, vs 73% of attacks for standard care (odds ratio [95% confidence interval] = 1.63 [1.14, 2.34], P <.01) and 72% of attacks for rizatriptan 5-mg wafer (OR [95% CI] = 1.60 [1.23, 2.08], P <.001). The median patient on rizatriptan 10-mg wafer was pain free at 2 hours in 46% of attacks, vs 30% of attacks for standard care (OR [95% CI] = 1.50 [1.06, 2.12], P <.05) and 25% of attacks for rizatriptan 5-mg wafer (OR [95% CI] = 1.93 [1.50, 2.49], P <.001). All treatments were generally well tolerated. Compared with standard care, rizatriptan 5-mg wafer was associated with fewer specific adverse events of asthenia/fatigue, back pain, nausea, pharyngeal discomfort, upper respiratory infection, and vomiting (P values <.05), and, compared with rizatriptan 10-mg wafer, fewer overall drug-related adverse events (P <.05). CONCLUSIONS: Rizatriptan 10-mg wafer was more effective than standard care and rizatriptan 5-mg wafer for treating intermittent moderate or severe migraine attacks occurring over periods of up to 6 months. Rizatriptan wafers were well tolerated.

Adult↗

Improved direct measurement of leptonic coupling asymmetries with polarized Z bosons.

We present final measurements of the Z boson-lepton coupling asymmetry parameters A(e), A(mu), and A(tau) with the complete sample of polarized Z bosons collected by the SLD detector at the SLAC Linear Collider. From the left-right production and decay polar angle asymmetries in leptonic Z decays we measure A(e) = 0.1544+/-0.0060, A(mu) = 0.142+/-0.015, and A(tau) = 0.136+/-0.015. Combined with our left-right asymmetry measured from hadronic decays, we find A(e) = 0.1516+/-0.0021. Assuming lepton universality, we obtain a combined effective weak mixing angle of sin (2)theta(eff)(W) = 0.230 98+/-0.000 26.

Journal Article↗

First symmetry tests in polarized Z0 decays to bbg.

We have made the first direct symmetry tests in the decays of polarized Z0 bosons into fully identified bbg states, collected in the SLD experiment at SLAC. We searched for evidence of parity violation at the bbg vertex by studying the asymmetries in the b-quark polar- and azimuthal-angle distributions, and for evidence of T-odd, CP-even or CP-odd, final-state interactions by measuring angular correlations between the three-jet plane and the Z0 polarization. We found results consistent with standard model expectations and set 95% C. limits on anomalous contributions.

Journal Article↗

Measuring the elastic properties of fine wire.

The elastic moduli of fine wires made from MP35N and 304SS used in implantable biomedical devices are assumed to be the same as those published in the literature. However, the cold working required to manufacture the wire significantly alters the elastic moduli of the material. We describe three experiments performed on fine wire made from MP35N and 304SS. The experimentally determined Young's and shear modulus of both wire types were significantly less than the moduli reported in the literature. Young's modulus differed by as much as 26%, and the shear modulus differed by as much as 14% from reported values.

Alloys↗

High-precision measurement of the left-right Z Boson cross-section asymmetry.

We present a measurement of the left-right cross-section asymmetry ( A(LR)) for Z boson production by e(+)e(-) collisions. The measurement includes the final data taken with the SLD detector at the SLAC Linear Collider during the period 1996-1998. Using a sample of 383 487 Z decays collected during the 1996-1998 runs we measure the pole value of the asymmetry, A(0)(LR), to be 0.150 56+/-0.002 39 which is equivalent to an effective weak mixing angle of sin (2)straight theta(eff)(W) = 0.231 07+/-0.000 30. Our result for the complete 1992-1998 data set comprising approximately 537 000 Z decays is sin (2)straight theta(eff)(W) = 0.230 97+/-0.000 27.

Journal Article↗

Development and clinical assessment of an artificial cornea.

Keratoprosthesis research has been a gradual, rather fragmentary process with advances being made by isolated groups of researchers. This has arisen partly because of poor funding in the area; research groups which have achieved commercial support have often had constraints upon the full disclosure of their findings. Despite these difficulties there has been real progress over the last decade by several independent groups. This article concentrates upon our own development of a hydrogel core-and-skirt keratoprosthesis, the Chirila KPro, in order to illustrate the scientific and clinical problems common to keratoprosthesis research. Pilot data from a clinical trial is presented and the priorities for future research are discussed.

Animals↗

Corneal biopsy with tissue micro-homogenisation for isolation of organisms in bacterial keratitis.

PURPOSE: To evaluate a novel two-stage technique to increase yield of bacteria isolated from infected corneal ulcers. METHODS: A new blade was designed to remove friable material from infected corneal ulcers. The new blade was used in combination with standard tissue micro-homogenisation equipment in a two-stage technique intended to distribute biopsy samples evenly between relevant agar plates. Patients with presumed-bacterial corneal ulcers underwent sequential corneal sampling using the new two-stage technique and a scalpel blade, used without micro-homogenisation (the order of sampling was varied between two groups). Bacterial isolation rates were compared using the chi-squared test. RESULTS: Twenty-four patients with presumed-bacterial corneal ulcers were studied. The overall positive bacterial isolation rate was 88%, with identical bacterial isolation rates for the new two-stage technique and the scalpel blade (71%). The new technique isolated bacteria from three ulcers that had initially been 'sterile' when sampled with a scalpel blade. Polymicrobial infections were identified in two ulcers with the new blade where only a single organism had been identified using the scalpel blade (not significantly different). CONCLUSIONS: The new two-stage technique shows promise for improving bacterial isolation rates from presumed-bacterial corneal ulcers.

Bacteria↗

Behavioral and electrophysiologic predictors of treatment response to stimulants in children with attention disorders.

Behavioral and quantitative electroencephalography (EEG) techniques were used to evaluate treatment response to stimulant therapy in children with attention disorders. A sample of 130 children with attention disorders were evaluated with Conners and Diagnostic and Statistical Manual of Mental Disorders--III rating scales, and with neurometric quantitative EEG before and 6 to 14 months after treatment with stimulants. Significant quantitative EEG differences were found between the normal control population (N = 31) and the children with attention problems. Quantitative EEG abnormalities involved increased theta or alpha power, greatest in frontal regions, frontal theta/alpha hypercoherence, and posterior interhemispheric power asymmetry. Behavioral improvement after stimulant treatment was seen in 81.5% of the children with attention-deficit hyperactivity disorder and 44.7% of the children with attention-deficit disorder, with the degree of correspondence between behavioral and quantitative EEG changes at 78.5%. Pretreatment clinical and quantitative EEG features could predict treatment response with a sensitivity of 83.1% and a specificity of 88.2%. A combined behavioral and quantitative EEG approach can be useful for following and predicting treatment response to stimulants in children with attention disorders.

Adolescent↗

Recycling steel. Conducting a waste audit.

This is the second in a series of three articles regarding steel can recycling from foodservice operations of healthcare facilities. This article highlights the basic methods of recycling steel cans, and includes information on conducting a waste audit and negotiating with a hauler regarding the benefits of recycling. The previous article discussed how steel is recycled across the country. The next article will convey a case history of actual foodservice recycling practice from a healthcare facility.

Conservation of Natural Resources↗