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B Cox

Publications and source records attributed to B Cox.

At least 37 records · Page 2Linked to original sources
PubMed2001

First measurement of form factors of the decay Xi(0) --> Sigma(+)e(-)nu macro(e).

We present the first measurement of the form factor ratios g(1)/f(1) (direct axial vector to vector), g(2)/f(1) (second class current), and f(2)/f(1) (weak magnetism) for the decay Xi(0)-->Sigma(+)e(-)nu macro(e) using the KTeV (E799) beam line and detector at Fermilab. From the Sigma(+) polarization measured with the decay Sigma(+)-->p pi(0) and the e(-)-nu; correlation, we measure g(1)/f(1) to be 1.32+/-(0.21)(0.17)(stat)+/-0.05(syst), assuming the SU(3)(f) (flavor) values for g(2)/f(1) and f(2)/f(1). Our results are all consistent with exact SU(3)(f) symmetry.

Journal Article↗
PubMed2001

Branching ratio measurement of the decay K(L) --> e(+)e(-)mu(+)mu(-).

We have collected a 43 event sample of the decay K(L)-->e(+)e(-)mu(+)mu(-) with negligible backgrounds and measured its branching ratio to be (2.62+/-0.40+/-0.17)x10(-9). We see no evidence for CP violation in this decay. In addition, we set the 90% confidence upper limit on the combined branching ratios for the lepton flavor violating decays K(L)-->e(+/-)e(+/-)mu(-/+)mu(-/+) at B(K(L)-->e(+/-)e(+/-)mu(-/+)mu(-/+))< or =1.23x10(-10), assuming a uniform phase space distribution.

Journal Article↗
PubMed2001

Measurement of the branching ratio and form factor of K(L)-->mu(+)mu(-)gamma.

We report on the analysis of the rare decay K(L)-->mu(+)mu(-)gamma the 1997 data from the KTeV experiment at Fermilab. A total of 9327 candidate events are observed with 2.4% background, representing a factor of 40 increase in statistics over the current world sample. We find that B(K(L)-->mu(+)mu(-)gamma) = (3.62 +/- 0.04(stat) +/- 0.08(syst)) x 10(-7). The form factor parameter alpha(K*) is measured to be alpha(K*) = -0.160(+0.026)(-0.028). In addition, we make the first measurement of the parameter alpha from the D'Ambrosio-Isidori-Portolés form factor, finding alpha = -1.54 +/- 0.10. In that model, this alpha measurement limits the Cabibbo-Kobayashi-Maskawa parameter rho>-0.2.

Journal Article↗
PubMed2001

Measurements of the rare decay K(L) --> e(+)e(-)e(+)e(-).

We observe 441 K(L)-->e(+)e(-)e(+)e(-) candidate events with a background of 4.2 events and measure B(K(L)-->e(+)e(-)e(+)e(-)) = [3.72+/-0.18(stat)+/-0.23(syst)]x10(-8) in the KTeV/E799II experiment at Fermilab. Using the distribution of the angle between the planes of the e(+)e(-) pairs, we measure the CP parameters beta(CP) = -0.23+/-0.09(stat)+/-0.02(syst) and gamma(CP) = -0.09+/-0.09(stat)+/-0.02(syst). We also present the first detailed study of the e(+)e(-) invariant mass spectrum in this decay mode.

Journal Article↗
PubMed2001

Measurement of the branching ratio and asymmetry of the decay Xi degrees -->Sigma degrees gamma.

We have studied the rare weak radiative hyperon decay Xi degrees -->Sigma degrees gamma in the KTeV experiment at Fermilab. We have identified 4045 signal events over a background of 804 events. The dominant Xi degrees -->Lambdapi degrees decay, which was used for normalization, is the only important background source. An analysis of the acceptance of both modes yields a branching ratio of B(Xi degrees -->Sigma degrees gamma)/B(Xi degrees -->Lambdapi degrees ) = (3.34+/-0.05+/-0.09)x10(-3). By analyzing the final state decay distributions, we have also determined that the Sigma degrees emission asymmetry parameter for this decay is alpha(XiSigma) = -0.63+/-0.09.

Journal Article↗
PubMed2001

Study of the K(0)(L) --> pi(+)pi(-)gamma Direct Emission Vertex.

We have performed studies of the K(0)(L)-->pi(+)pi(-)gamma direct emission ( DE) and inner Bremsstrahlung ( IB) vertices, based on data collected by KTeV during the 1996 Fermilab fixed target run. We find a(1)/a(2) = -0.737+/-0.034 GeV2 for the DE form-factor parameter in the rho-propagator parametrization, and report on fits of the form factor to linear and quadratic functions as well. We concurrently measure gamma(K(0)(L)-->pi(+)pi(-)gamma,E(*)(gamma)>20 MeV)/gamma(K(0)(L)-->pi(+)pi(-)) = (20.8+/-0.3)x10(-3), and a K(0)(L)-->pi(+)pi(-)gamma DE/(DE+IB) branching ratio of 0.683+/-0.011.

Journal Article↗
PubMed2001

Search for the decay KL --> pi(0)e+e-.

We report on a search for the decay KL-->pi(0)e+e- carried out by the KTeV/E799 experiment at Fermilab. This decay is expected to have a significant CP violating contribution and the measurement of its branching ratio could support the Cabibbo-Kobayashi-Maskawa mechanism for CP violation or could point to new physics. Two events were observed in the 1997 data with an expected background of 1.06+/-0.41 events, and we set an upper limit B(KL-->pi(0)e+e-)<5.1 x 10(-10) at the 90% confidence level.

Journal Article↗
PubMed2001

High prevalence of vasectomy in New Zealand.

The aim of this study was to examine the prevalence of vasectomy and associated factors in New Zealand, based on interviews with men. Participants were randomly selected from European men, aged between 40 and 74 years, on the general electoral roll. Telephone interviews were completed with 1225 men between 1997 and 1999. Overall, the prevalence of vasectomy was 44% (95% CI, 37-52%), adjusted to the age distribution of all New Zealand men aged 40-74 years. The prevalence ranged from 57% of men aged 40-49 years to 15% of those aged 70-74 years. Catholic men had a significantly lower odds of vasectomy, and there was a trend in increasing odds of vasectomy with increasing number of marriages and level of education of the wife. The results confirm a very high prevalence of vasectomy among New Zealand men. Comparison with earlier surveys based on interviews of women showed an increasing prevalence of vasectomy in each birth cohort from the 1920s to the 1950s. Vasectomy has been popular with men across all socioeconomic groups. New Zealand is an ideal country in which to study consequences of vasectomy.

Adult↗
PubMed2001

Positional cloning of a novel Fanconi anemia gene, FANCD2.

Fanconi anemia (FA) is a genetic disease with birth defects, bone marrow failure, and cancer susceptibility. To date, genes for five of the seven known complementation groups have been cloned. Complementation group D is heterogeneous, consisting of two distinct genes, FANCD1 and FANCD2. Here we report the positional cloning of FANCD2. The gene consists of 44 exons, encodes a novel 1451 amino acid nuclear protein, and has two protein isoforms. Similar to other FA proteins, the FANCD2 protein has no known functional domains, but unlike other known FA genes, FANCD2 is highly conserved in A. thaliana, C. elegans, and Drosophila. Retroviral transduction of the cloned FANCD2 cDNA into FA-D2 cells resulted in functional complementation of MMC sensitivity.

Alleles↗
PubMed2001

Validation of the saliva-based H. pylori test, heliSAL, and its use in prevalence surveys.

The saliva-based H. pylori test, HeliSAL, is insufficiently accurate for use in the clinical setting. However, its ease of use and non-invasiveness make it attractive for population-based studies of the epidemiology of H. pylori. We validated HeliSAL, and comment here on its usefulness in prevalence surveys. One hundred and ninety-six patients receiving endoscopy at a clinic in New Zealand provided saliva samples for H. pylori assessment, which were compared to CLOtest (Delta West Pty Ltd, Western Australia) as a gold standard measure. Nineteen percent were truly H. pylori positive, 41% were positive according to HeliSAL. Test sensitivity was 74% and specificity was 67%. While HeliSAL is not well suited for the clinical diagnosis of H. pylori infection, it may be useful for large-scale prevalence surveys because, provided it is validated locally, mathematical adjustment can be made for misclassification. Being inexpensive, non-invasive, and easily stored and handled, HeliSAL may be a valuable tool for studies of the epidemiology of H. pylori.

Adult↗
PubMed2001

Oxidative stress in the aging rat heart is reversed by dietary supplementation with (R)-(alpha)-lipoic acid.

Oxidative stress has been implicated as a causal factor in the aging process of the heart and other tissues. To determine the extent of age-related myocardial oxidative stress, oxidant production, antioxidant status, and oxidative DNA damage were measured in hearts of young (2 months) and old (28 months) male Fischer 344 rats. Cardiac myocytes isolated from old rats showed a nearly threefold increase in the rate of oxidant production compared to young rats, as measured by the rates of 2,7-dichlorofluorescin diacetate oxidation. Determination of myocardial antioxidant status revealed a significant twofold decline in the levels of ascorbic acid (P = 0.03), but not alpha-tocopherol. A significant age-related increase (P = 0.05) in steady-state levels of oxidative DNA damage was observed, as monitored by 8-oxo-2'-deoxyguanosine levels. To investigate whether dietary supplementation with (R)-alpha-lipoic acid (LA) was effective at reducing oxidative stress, young and old rats were fed an AIN-93M diet with or without 0.2% (w/w) LA for 2 wk before death. Cardiac myocytes from old, LA-supplemented rats exhibited a markedly lower rate of oxidant production that was no longer significantly different from that in cells from unsupplemented, young rats. Lipoic acid supplementation also restored myocardial ascorbic acid levels and reduced oxidative DNA damage. Our data indicate that the aging rat heart is under increased mitochondrial-induced oxidative stress, which is significantly attenuated by lipoic acid supplementation.

Aging↗
PubMed2001

Indirect institutional revenue generated from an academic primary care clinical network.

BACKGROUND AND OBJECTIVES: As the financial performances of US academic health centers have faltered under managed care and the Balanced Budget Act of 1997, increasing attention has been paid to the costs and benefits of operating primary care networks. This study examines the indirect revenues to a university hospital and faculty group practice that result from such a primary care network using a method of abstracting billing data. METHODS: A primary care patient cohort was identified by selecting all patients who generated at least one charge in any of the 10 primary care clinics in the network over a 15-month period. All charges from the hospital and the faculty practice group for this cohort were then examined during a 6-month period, and the total charges generated in the primary care setting were compared with charges generated elsewhere in the health system. RESULTS: The primary care patient cohort included 56,459 patients and generated a total of $7,243,312 in charges for primary care services, $43,559,741 of charges in the hospital billing system for non-primary care services, and $8,825,611 of charges for services from specialty faculty. This cohort accounted for 18.5% of the gross charges for hospital care and 17.6% of charges generated by the specialty physicians. CONCLUSIONS: Using a simple and replicable methodology, this study estimates a substantial financial benefit to the hospital and specialty practices from a primary care network.

Academic Medical Centers↗
PubMed2000

Search for the decay K(L) --> pi(0)&mgr;(+)&mgr;(-)

We report on a search for the decay K(L)-->pi(0)&mgr;(+)&mgr;(-) carried out as a part of the KTeV experiment at Fermilab. This decay is expected to have a significant CP violating contribution and a direct measurement will either support the Cabibbo-Kobayashi-Maskawa mechanism for CP violation or point to new physics. Two events were observed in the 1997 data with an expected background of 0.87+/-0.15 events, and we set an upper limit B(K(L)-->pi(0)&mgr;(+)&mgr;(-))<3. 8x10(-10) at the 90% confidence level.

Journal Article↗
PubMed2000

Guidelines for the management of women with abnormal cervical smears 1998.

Four important changes have been introduced in the revised guidelines for the management of women with abnormal cervical smears, 1998. 1. For the purposes of management, atypical squamous cells of undetermined significance (ASCUS) and atypical glandular cells of undetermined significance (AGUS) have been included with low grade squamous intraepithelial lesions (LSIL/CIN1/HPV) except where the smear raises the possibility of a high grade squamous intraepthelial lesion (HSIL) or favours glandular dysplasia. 2. Women with low grade cytological and histological intraepithelial abnormalities will, after initial follow-up, revert to three yearly screening. 3. Requirements for those practising colposcopy have been defined. 4. A formal review of all cases of invasive cervical cancer is advocated.

Adenocarcinoma↗
PubMed2000

Search for the weak decay of a lightly bound H0 dibaryon

We present results of a search for a new form of hadronic matter, a six-quark, dibaryon state called the H0, a state predicted to exist in several theoretical models. Analyzing data collected by experiment E799-II at Fermilab, we searched for the decay H0-->Lambdappi(-) and found no candidate events. We place an upper limit on [B(H0-->Lambdappi(-))dsigma(H)/dOmega]/(dsigma(Xi)/dOmega) and, in the context of published models, exclude the region of lightly bound mass states just below the LambdaLambda mass threshold, 2.194<M(H)<2.231 GeV/c(2), with lifetimes from approximately 5x10(-10) sec to approximately 1x10(-3) sec.

Journal Article↗
PubMed2000

An evaluation of the National Cervical Screening Programme Otago site.

AIM: To evaluate progress of the Otago Cervical Screening Programme towards achieving its goal of reducing cervical cancer incidence and mortality using data routinely collected by the National Cervical Screening Register (NCSR), and to investigate whether all data required for this task are available from the NCSR. METHOD: Non-identifying data for Otago women aged 20-69 years were obtained from the New Zealand National Cervical Screening Register for the period 1 July 1993 to 30 June 1996. For each five-year age group, proportion screened in three years, short interval re-screening estimates and age-specific reporting rates for squamous atypia of uncertain significance (ASCUS), low-grade intraepithelial lesions (LGIL) and high-grade intraepithelial lesions (HGIL) were calculated. Age-specific reporting rates were also calculated for 20-69 year-old New Zealand women for the same period and compared to the Otago rates. RESULTS: The proportion of eligible women screened was 82.5%, slightly less than the target 85%. Women aged 55 years or more were underscreened, short interval rescreening was more common among younger women, age-specific reporting rates for ASCUS, LGIL and HGIL had increased since 1991/92, and the rate of HGIL was higher than expected in the 20-34 year age group. CONCLUSIONS: In order to maximise the effectiveness and efficiency of the Otago Cervical Screening Programme, it is recommended that participation amongst older women be increased and frequent screening be reduced in the younger age groups. Unexpected elevated rates of HGIL amongst 20-34 year-old women were not adequately explained and require further investigation. Not all data required for an outcome evaluation were available through the NCSR.

Adult↗
PubMed2000

Observation of CP violation in K(L)-->pi(+)pi(-)e(+)e(-) decays

We report the first observation of a manifestly CP violating effect in the K(L)-->pi(+)pi(-)e(+)e(-) decay mode. A large asymmetry was observed in the distribution of these decays in the CP-odd and T-odd angle straight phi between the decay planes of the e(+)e(-) and pi(+)pi(-) pairs in the K(L) center of mass system. After acceptance corrections, the overall asymmetry is found to be [13.6+/-2. 5(stat)+/-1.2(syst)]%. This is the largest CP-violating effect yet observed when integrating over the entire phase space of a mode and the first such effect observed in an angular variable.

Journal Article↗