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S Barrow

Publications and source records attributed to S Barrow.

At least 19 recordsLinked to original sources
PubMed2004

Observation of an exotic baryon with S=+1 in photoproduction from the proton.

The reaction gamma p-->pi(+)K(-)K(+)n was studied at Jefferson Laboratory using a tagged photon beam with an energy range of 3-5.47 GeV. A narrow baryon state with strangeness S=+1 and mass M=1555+/-10 MeV/c(2) was observed in the nK(+) invariant mass spectrum. The peak's width is consistent with the CLAS resolution (FWHM=26 MeV/c(2)), and its statistical significance is (7.8+/-1.0)sigma. A baryon with positive strangeness has exotic structure and cannot be described in the framework of the naive constituent quark model. The mass of the observed state is consistent with the mass predicted by the chiral soliton model for the Theta(+) baryon. In addition, the pK(+) invariant mass distribution was analyzed in the reaction gamma p-->K(-)K(+)p with high statistics in search of doubly charged exotic baryon states. No resonance structures were found in this spectrum.

Journal Article↗
PubMed2003

Measurement of the proton spin structure function g1(x,Q2) for Q2 from 0.15 to 1.6 GeV2 with CLAS.

Double-polarization asymmetries for inclusive ep scattering were measured at Jefferson Lab using 2.6 and 4.3 GeV longitudinally polarized electrons incident on a longitudinally polarized NH3 target in the CLAS detector. The polarized structure function g(1)(x,Q2) was extracted throughout the nucleon resonance region and into the deep inelastic regime, for Q(2)=0.15-1.64 GeV2. The contributions to the first moment Gamma(1)(Q2)= integral g(1)(x,Q2) dx were determined up to Q(2)=1.2 GeV2. Using a parametrization for g(1) in the unmeasured low x regions, the complete first moment was estimated over this Q2 region. A rapid change in Gamma(1) is observed for Q2<1 GeV2, with a sign change near Q(2)=0.3 GeV2, indicating dominant contributions from the resonance region. At Q(2)=1.2 GeV2 our data are below the perturbative QCD evolved scaling value.

Journal Article↗
PubMed2003

Measurement of ep-->e' ppi+ pi- and baryon resonance analysis.

The cross section for the reaction ep-->e(')ppi(+)pi(-) was measured in the resonance region for 1.4<W<2.1 GeV and 0.5<Q2<1.5 GeV(2)/c(2) using the CLAS detector at Jefferson Laboratory. The data show resonant structures not visible in previous experiments. The comparison of our data to a phenomenological prediction using available information on N(*) and Delta states shows an evident discrepancy. A better description of the data is obtained either by a sizable change of the properties of the P13(1720) resonance or by introducing a new baryon state, not reported in published analyses.

Journal Article↗
PubMed2003

Photoproduction of the omega meson on the proton at large momentum transfer.

The differential cross section, dsigma/dt, for omega meson exclusive photoproduction on the proton above the resonance region (2.6<W<2.9 GeV) was measured up to a momentum transfer -t=5 GeV2 using the CLAS detector at Jefferson Laboratory. The omega channel was identified by detecting a proton and pi(+) in the final state and using the missing mass technique. While the low momentum transfer region shows the typical diffractive pattern expected from Pomeron and Reggeon exchange, at large -t the differential cross section has a flat behavior. This feature can be explained by introducing quark interchange processes in addition to the QCD-inspired two-gluon exchange.

Journal Article↗
PubMed2002

Eta photoproduction on the proton for photon energies from 0.75 to 1.95 GeV.

Differential cross sections for gammap-->etap have been measured with tagged real photons for incident photon energies from 0.75 to 1.95 GeV. Mesons were identified by missing mass reconstruction using kinematical information for protons scattered in the production process. The data provide the first extensive angular distribution measurements for the process above W=1.75 GeV. Comparison with preliminary results from a constituent quark model support the suggestion that a third S11 resonance with mass approximately 1.8 GeV couples to the etaN channel.

Journal Article↗
PubMed2002

Q2 Dependence of quadrupole strength in the gamma*p --> Delta(+)(1232) --> p pi(0) transition.

Models of baryon structure predict a small quadrupole deformation of the nucleon due to residual tensor forces between quarks or distortions from the pion cloud. Sensitivity to quark versus pion degrees of freedom occurs through the Q2 dependence of the magnetic (M1+), electric (E1+), and scalar (S1+) multipoles in the gamma*p-->Delta(+)-->p pi(0) transition. We report new experimental values for the ratios E(1+)/M(1+) and S(1+)/M(1+) over the range Q2 = 0.4-1.8 GeV2, extracted from precision p(e,e(')p)pi(0) data using a truncated multipole expansion. Results are best described by recent unitary models in which the pion cloud plays a dominant role.

Journal Article↗
PubMed2002

First measurement of the double spin asymmetry in (-->)e(-->)p-->e(prime)pi(+)n in the resonance region.

The double spin asymmetry in the (-->)e(-->)p --> e(prime)pi(+)n reaction has been measured for the first time in the resonance region for four-momentum transfer Q2 = 0.35-1.5 GeV(2). Data were taken at Jefferson Lab with the CLAS detector using a 2.6 GeV polarized electron beam incident on a polarized solid NH3 target. Comparison with predictions of phenomenological models shows strong sensitivity to resonance contributions. Helicity-1/2 transitions are found to be dominant in the second and third resonance regions. The measured asymmetry is consistent with a faster rise with Q(2) of the helicity asymmetry A1 for the F(15)(1680) resonance than expected from the analysis of the unpolarized data.

Journal Article↗
PubMed2002

A visual motor psychological test as a predictor to treatment in nocturnal enuresis.

BACKGROUND AND AIMS: The neurological control of bladder function and the ability to be dry at night involves not only the acquisition of normal daytime control, but also the establishment of a circadian rhythm in vasopressin release and the ability to arouse to a full bladder during sleep. We postulated that in some children there might be a delay in maturation of the normal neurological pathways involved in establishment of nocturnal continence and examined this by using a specific neuropsychological test. METHODS: Children attending an established nocturnal enuresis clinic were examined using the Rey-Osterrieth test to assess the presence or absence of boundary errors in both copy and memory reproductions. The results of the test were scored independently and blind to the response to treatment with the vasopressin analogue DDAVP. RESULTS: A significant association was found between boundary type errors and response to DDAVP, with non-responders making significantly more errors. No child with three or more errors responded to DDAVP. Using this test, the ability to predict response to treatment was 70%. CONCLUSIONS: It is postulated that the Rey-Osterrieth test, through the presence or absence of boundary errors, reflects a delay in maturation and/or a disorganisation of the retinal-hypothalamic-cortical pathways in the brain. The association previously described with growth hormone neurosecretory dysfunction syndrome would be compatible with this.

Child↗
PubMed2001

Photoproduction of the rho(0) meson on the proton at large momentum transfer.

The differential cross section, d sigma/dt, for rho(0) meson photoproduction on the proton above the resonance region was measured up to a momentum transfer -t = 5 GeV2 using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The rho(0) channel was extracted from the measured two charged-pion cross sections by fitting the pi(+)pi(-) and p pi(+) invariant masses. The low momentum transfer region shows the typical diffractive pattern expected from Reggeon exchange. The flatter behavior at large -t cannot be explained solely in terms of QCD-inspired two-gluon exchange models. The data indicate that other processes, like quark interchange, are important to fully describe rho photoproduction.

Journal Article↗
PubMed2001

The ep -->e'p eta reaction at and above the S11(1535) baryon resonance.

New cross sections for the reaction e p-->e p eta are reported for total center of mass energy W = 1.5--1.86 GeV and invariant momentum transfer Q2 = 0.25--1.5 (GeV/c)(2). This large kinematic range allows extraction of important new information about response functions, photocouplings, and eta N coupling strengths of baryon resonances. Newly observed structure at W approximately 1.65 GeV is shown to come from interference between S and P waves and can be interpreted with known resonances. Improved values are derived for the photon coupling amplitude for the S11(1535) resonance.

Journal Article↗
PubMed2001

Unpacking the black box of nursing and therapy practice for post-stroke shoulder pain: a precursor to evaluation.

OBJECTIVES: To describe current nursing and therapy interventions for the prevention and treatment of post-stroke shoulder pain and to explore the extent of their reported use in England. DESIGN: Semi-structured, the med interviews followed by a postal questionnaire. PARTICIPANTS: Six nurses, five occupational therapists (OTs) and six physiotherapists (PTs) were interviewed. Twelve nurses, 12 OTs and 12 PTs were sent the pilot questionnaire and the main questionnaire was posted to 332 nurses, 332 OTs and 332 PTs. SETTING: NHS Trusts in England which provide acute stroke care/rehabilitation. PROCEDURE: Two researchers independently condensed the transcripts of the interviews into a list of interventions which were then transformed into a pilot postal questionnaire. Following the pilot small changes were made. Participants sent the main questionnaire were given three weeks to return it before being posted a reminder. After a further two weeks a researcher gave a telephone reminder. RESULTS: One hundred and seventy-five different types of interventions were identified. The main questionnaire (57.8% response rate) found that all of the interventions were used by at least one respondent and that only 22.9% of the interventions were used to the same extent by nurses, OTs and PTs. The data also suggest variation in reported use within professions. CONCLUSIONS: This study has found a large number of interventions for post-stroke shoulder pain which are reported to be used. This might reflect different causes of shoulder pain or variation between clinicians. Answers to these questions are expected to guide future evaluative research.

Health Care Surveys↗
PubMed2000

Recruitment strategies in the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial: the first six years.

The Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial has a total enrollment goal of almost 150,000 participants. These participants are being recruited at ten screening centers across the United States. All screening centers tested recruitment methodologies during a 1-year pilot phase. The main phase of recruitment was planned to take place over a 3-year period. The majority of participants are being recruited during the main phase of the study. Each of the screening centers tailors recruitment to its individual catchment area. Recruitment strategies in the PLCO trial are described. As the trial began, several protocol changes were made to help to increase enrollment. The National Cancer Institute (NCI) initiated recruitment efforts at the national level. The individual screening centers describe some of the specific recruitment experiences encountered. As the study progressed, the NCI implemented special initiatives to increase the enrollment of minority participants.

Aged↗
PubMed1999

Social determinants of GHQ score by postal survey.

BACKGROUND: To develop interventions to reduce the morbidity associated with depression and anxiety, more information is needed about the social and demographic determinants of these disorders and the relative contributions of different potential predictors. METHODS: Using stratified sampling from the Family Health Services Authority (FHSA) register, postal surveys were sent to 61,000 adults across the North Western Regional Health Authority. Psychological morbidity was assessed using the 12-item General Health Questionnaire (GHQ). Nine potential predictors of morbidity were rated, including socio-demographic details and the presence of longstanding limiting physical illness and of a confidante. Logistic regression analyses were used to consider each of the nine potential predictors separately and in combination. RESULTS: A total of 38,014 questionnaires were returned (63 per cent). After adjustment for all other variables the strongest predictors of a high GHQ score were the absence of a confidante (odds ratio (OR) 3.64), longstanding limiting physical illness (OR 2.93), unemployment (OR 1.91), being a student (OR 1.78), being female (OR 1.64), single parenthood (OR 1.55) and living alone (OR 1.32). GHQ scores were highest in the 18-34 age range. Ethnicity exerted no significant effect after adjustment for other variables. CONCLUSION: In keeping with other research the data suggest that sociodemographic factors are strong predictors of depression and anxiety. The most vulnerable population groups are those with longstanding limiting physical illness and no-one to talk to. This should help in identifying high-risk individuals and informing preventive strategies.

Adolescent↗
PubMed1998

Mental health in the north west region of England: associations with deprivation.

Minor psychiatric morbidity is known to be associated with social disadvantage, but few studies have explored this association at the population level. This study reports data from a postal survey across 19 health districts in one region, with a total sample of 38,000 respondents. The percentage scoring above the General Health Questionnaire (GHQ) threshold for each health district was correlated with measures of deprivation derived from the 1991 census and standardised mortality ratios. Highly significant correlations were seen between the percentage above the GHQ threshold and the Underprivileged Area (UPA) score (r = 0.84), under 65 Standardised Mortality Ratio (SMR; r = 0.80), lack of amenities (r = 0.56), overcrowding (r = 0.54), lone-parent families (r = 0.84), unemployment (r = 0.87), unskilled workers (r = 0.77), ethnic minority composition (r = 0.58) and social mobility (r = 0.85). However, the three most deprived districts had the lowest response rates and when these were excluded from the analysis, only the correlations with under 65 SMR (r = 0.57, P < 0.05), UPA score (r = 0.52, P < 0.05) and unskilled workers (r = 0.60, P < 0.05) remained significant. There may be a threshold effect for the impact of social disadvantage on mental health, with much higher rates of psychological morbidity among markedly disadvantaged populations.

Adult↗
PubMed1998

Informal care and psychiatric morbidity.

BACKGROUND: We aimed to examine and quantify the relationship between psychiatric morbidity and the provision of informal care in the community. METHODS: The study involved a comparison of carers and non-carers in a mixed urban and rural community (Morecambe Bay Health Authority). Data were collected by postal survey for 4550 adults; 10.9 per cent of respondents were identified as carers. Subjects were selected by quasi-random methods from the Family Health Services Authority (FHSA) registers. Potential psychiatric morbidity was defined as three or more symptoms on a standardized measure, the General Health Questionnaire (12-item version). RESULTS: The prevalence of morbidity was significantly higher in people who care for others in their own homes, even after adjustment for other known risk factors for psychiatric morbidity (odds ratio 1.51, 95 per cent confidence interval 1.11-2.05). In contrast, there was no significant relationship between morbidity and care outside the home in these data. CONCLUSION: Health Authorities need to review support for carers and to consider ways to improve monitoring.

Adult↗