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Biomedical subjects

C Gould

Publications and source records attributed to C Gould.

At least 19 recordsLinked to original sources
PubMed2006

Magnetization-switched metal-insulator transition in a (Ga,Mn)as tunnel device.

We observe the occurrence of an Efros-Shklovskii gap in (Ga,Mn)As based tunnel junctions. The occurrence of the gap is controlled by the extent of the hole wave function on the Mn acceptor atoms. Using k.p-type calculations we show that this extent depends crucially on the direction of the magnetization in the (Ga,Mn)As (which has two almost equivalent easy axes). This implies one can reversibly tune the system into the insulating or metallic state by changing the magnetization.

Journal Article↗
PubMed2006

Remanent zero field spin splitting of self-assembled quantum dots in a paramagnetic host.

We report on the observation of a finite spin splitting at zero magnetic field in resonant tunneling experiments on CdSe self-assembled quantum dots in a (Zn,Be,Mn)Se barrier. This is remarkable since bulk II-VI dilute magnetic semiconductors are paramagnets. Our experiment may be viewed as tunneling through a single magnetic polaron, where the carriers contained inside the dot act to mediate an effective ferromagnetic interaction between Mn ions in their vicinity. The effect is observable up to relatively high temperatures, which we tentatively ascribe to a feedback mechanism with the electrical current, previously predicted theoretically.

Journal Article↗
PubMed2005

Very large tunneling anisotropic magnetoresistance of a (Ga,Mn)As/GaAs/(Ga,Mn)As stack.

We report the discovery of a very large tunneling anisotropic magnetoresistance in an epitaxially grown (Ga,Mn)As/GaAs/(Ga,Mn)As structure. The key novel spintronics features of this effect are as follows: (i) both normal and inverted spin-valve-like signals; (ii) a large nonhysteretic magnetoresistance for magnetic fields perpendicular to the interfaces; (iii) magnetization orientations for extremal resistance are, in general, not aligned with the magnetic easy and hard axis; (iv) enormous amplification of the effect at low bias and temperatures.

Journal Article↗
PubMed2005

General practice critical incident reviews of patient suicides: benefits, barriers, costs, and family participation.

AIM: To explore the feasibility of holding critical incident reviews (CIRs) after patient suicides in general practice and their ability to change practice. METHODS: Thirteen practices were invited to conduct a facilitated CIR on 18 current patient suicides. Next of kin views were sought. All staff attending a CIR were interviewed after the review. RESULTS: Ten practices reviewed 12 deaths. Twenty six staff attended reviews; all were interviewed. Next of kin contributed to six reviews; only one criticised care. Changes following the reviews included steps to improve internal communication and bereavement support to set up internal CIRs and review prescribing policies. Communications between practices and other agencies were clarified. CONCLUSION: Practices were willing to hold CIRs and appreciated the potential positive value but need reassurance that they will not be blamed for suicides, and that the cost in time and resources will be recognised.

Family↗
PubMed2004

Tunneling anisotropic magnetoresistance: a spin-valve-like tunnel magnetoresistance using a single magnetic layer.

We introduce a new class of spintronic devices in which a spin-valve-like effect results from strong spin-orbit coupling in a single ferromagnetic layer rather than from injection and detection of a spin-polarized current by two coupled ferromagnets. The effect is observed in a normal-metal-insulator-ferromagnetic-semiconductor tunneling device. This behavior is caused by the interplay of the anisotropic density of states in (Ga,Mn)As with respect to the magnetization direction and the two-step magnetization reversal process in this material.

Journal Article↗
PubMed2004

Spin injection in the nonlinear regime: band bending effects.

We report on electrical spin-injection measurements into a nonmagnetic semiconductor in the nonlinear regime. For voltage drops across the interface larger than a few mV the spin-injection efficiency decreases strongly. The effect is caused by repopulation of the minority spin level in the magnetic semiconductor due to band bending at the interface.

Journal Article↗
PubMed2003

Very large magnetoresistance in lateral ferromagnetic (Ga,Mn)as wires with nanoconstrictions.

We have fabricated (Ga,Mn)As nanostructures in which domain walls can be pinned by sub-10 nm constrictions. Controlled by shape anisotropy, we can switch the regions on either side of the constriction to either parallel or antiparallel magnetization. All samples exhibit a positive magnetoresistance, consistent with domain-wall trapping. For metallic samples, we find a magnetoresistance up to 8%, which can be understood from spin accumulation. In samples where, due to depletion at the constriction, a tunnel barrier is formed, we observe a magnetoresistance of up to 2000%.

Journal Article↗
PubMed2003

Voltage-controlled spin selection in a magnetic resonant tunneling diode.

We have fabricated all II-VI semiconductor resonant tunneling diodes based on the (Zn,Mn,Be)Se material system, containing dilute magnetic material in the quantum well, and studied their current-voltage characteristics. When subjected to an external magnetic field the resulting spin splitting of the levels in the quantum well leads to a splitting of the transmission resonance into two separate peaks. This is interpreted as evidence of tunneling transport through spin polarized levels, and could be the first step towards a voltage controlled spin filter.

Journal Article↗
PubMed2001

Large magnetoresistance effect due to spin injection into a nonmagnetic semiconductor.

A novel magnetoresistance effect, due to the injection of a spin-polarized electron current from a dilute magnetic into a nonmagnetic semiconductor, is presented. The effect results from the suppression of a spin channel in the nonmagnetic semiconductor and can theoretically yield a positive magnetoresistance of 100%, when the spin flip length in the nonmagnetic semiconductor is sufficiently large. Experimentally, our devices exhibit up to 25% magnetoresistance.

Journal Article↗
PubMed2001

Observational study of effect of patient centredness and positive approach on outcomes of general practice consultations.

OBJECTIVE: To measure patients' perceptions of patient centredness and the relation of these perceptions to outcomes. DESIGN: Observational study using questionnaires. SETTING: Three general practices. PARTICIPANTS: 865 consecutive patients attending the practices. MAIN OUTCOME MEASURES: Patients' enablement, satisfaction, and burden of symptoms. RESULTS: Factor analysis identified five components. These were communication and partnership (a sympathetic doctor interested in patients' worries and expectations and who discusses and agrees the problem and treatment, Cronbach's alpha=0.96); personal relationship (a doctor who knows the patient and their emotional needs, alpha=0.89); health promotion (alpha=0.87); positive approach (being definite about the problem and when it would settle, alpha=0.84); and interest in effect on patient's life (alpha=0.89). Satisfaction was related to communication and partnership (adjusted beta=19.1; 95% confidence interval 17.7 to 20.7) and a positive approach (4.28; 2.96 to 5.60). Enablement was greater with interest in the effect on life (0.55; 0.25 to 0.86), health promotion (0.57; 0.30 to 0.85), and a positive approach (0.82; 0.52 to 1.11). A positive approach was also associated with reduced symptom burden at one month (beta=-0.25; -0.41 to -0.10). Referrals were fewer if patients felt they had a personal relationship with their doctor (odds ratio 0.70; 0.54 to 0.90). CONCLUSIONS: Components of patients' perceptions can be measured reliably and predict different outcomes. If doctors don't provide a positive, patient centred approach patients will be less satisfied, less enabled, and may have greater symptom burden and higher rates of referral.

Communication↗
PubMed2001

Preferences of patients for patient centred approach to consultation in primary care: observational study.

OBJECTIVE: To identify patient's preferences for patient centred consultation in general practice. DESIGN: Questionnaire study. SETTING: Consecutive patients in the waiting room of three doctors' surgeries. MAIN OUTCOME MEASURES: Key domains of patient centredness from the patient perspective. Predictors of preferences for patient centredness, a prescription, and examination. RESULTS: 865 patients participated: 824 (95%) returned the pre-consultation questionnaire and were similar in demographic characteristic to national samples. Factor analysis identified three domains of patient preferences: communication (agreed with by 88-99%), partnership (77-87%), and health promotion (85-89%). Fewer wanted an examination (63%), and only a quarter wanted a prescription. As desire for a prescription was modestly associated with desire for good communication (odds ratio 1.20; 95% confidence interval 0.85 to 1.69), partnership (1.46; 1.01 to 2.09), and health promotion (1.61; 1.12 to 2.31) this study may have underestimated preferences for patient centredness compared with populations with stronger preferences for a prescription. Patients who strongly wanted good communication were more likely to feel unwell (very, moderately, and slightly unwell; odds ratios 1, 0.56, 0.39 respectively, z trend P<0.001), be high attenders (1.70; 1.18 to 2.44), and have no paid work (1.84; 1.21 to 2.79). Strongly wanting partnership was also related to feeling unwell, worrying about the problem, high attendance, and no paid work; and health promotion to high attendance and worry. CONCLUSION: Patients in primary care strongly want a patient centred approach, with communication, partnership, and health promotion. Doctors should be sensitive to patients who have a strong preference for patient centredness-those vulnerable either psychosocially or because they are feeling unwell.

Adolescent↗
PubMed2001

Pragmatic randomised controlled trial of two prescribing strategies for childhood acute otitis media.

OBJECTIVE: To compare immediate with delayed prescribing of antibiotics for acute otitis media. DESIGN: Open randomised controlled trial. SETTING: General practices in south west England. PARTICIPANTS: 315 children aged between 6 months and 10 years presenting with acute otitis media. INTERVENTIONS: Two treatment strategies, supported by standardised advice sheets-immediate antibiotics or delayed antibiotics (antibiotic prescription to be collected at parents' discretion after 72 hours if child still not improving). MAIN OUTCOME MEASURES: Symptom resolution, absence from school or nursery, paracetamol consumption. RESULTS: On average, symptoms resolved after 3 days. Children prescribed antibiotics immediately had shorter illness (-1.1 days (95% confidence interval -0.54 to -1.48)), fewer nights disturbed (-0.72 (-0.30 to -1.13)), and slightly less paracetamol consumption (-0.52 spoons/day (-0.26 to -0.79)). There was no difference in school absence or pain or distress scores since benefits of antibiotics occurred mainly after the first 24 hours-when distress was less severe. Parents of 36/150 of the children given delayed prescriptions used antibiotics, and 77% were very satisfied. Fewer children in the delayed group had diarrhoea (14/150 (9%) v 25/135 (19%), chi(2)=5.2, P=0.02). Fewer parents in the delayed group believed in the effectiveness of antibiotics and in the need to see the doctor with future episodes. CONCLUSION: Immediate antibiotic prescription provided symptomatic benefit mainly after first 24 hours, when symptoms were already resolving. For children who are not very unwell systemically, a wait and see approach seems feasible and acceptable to parents and should substantially reduce the use of antibiotics for acute otitis media.

Acetaminophen↗
PubMed1999

UK neonatal intensive care services in 1996. On behalf of the UK Neonatal Staffing Study Collaborative Group.

A census of activity and staff levels in 1996 was conducted in UK neonatal units and achieved a 100% response from 246 units. Among the 186 neonatal intensive care units, the median (interquartile range) number of total cots was 18(14-22); level 1 intensive care cots 4(2-6); total admissions 318(262-405); very low birthweight admissions 40(28-68); and the number ventilated or given CPAP by endotracheal tube 52(32-83). Forty six (25%) intensive care units lacked the recommended minimum of one consultant with prime responsibility for neonatal medicine. As a conservative estimate 79% of intensive care units had a lower nursing provision than that recommended in previously published guidelines. There was substantial variation in activity and staffing levels among units.

Hospital Bed Capacity↗
PubMed1998

Risk-factor assessment for falls: from a written checklist to the penless clinic.

OBJECTIVE: to audit risk-factor identification of fallers before and after an education programme and the insertion of a written checklist in medical notes. Risk-factor identification in a dedicated, computerized falls clinic was then examined. METHODS: documentation of risk factors for falls was studied on wards and a self-auditing 'penless' clinic for fallers subsequently set up to generate reports for medical notes and letters for general practitioners. RESULTS: risk-factor identification improved after the insertion of the checklist but remained relatively poor. A dedicated clinic allowed almost complete identification of risk factors. Of the first 112 patients (median age 82) seen in the clinic, 75 (67%) were housebound. Remediable risk factors--e.g. inappropriate medication (67%), unsatisfactory footwear (59%) and postural hypotension (17%)--were found in most. Thirty-three patients (29%) had difficulty with alarm raising. CONCLUSION: ward-based intervention showed limited capacity to identify risk factors for falls: a dedicated clinic was more successful. The use of a portable computer with a programme to screen fallers for risk factors is worthy of consideration.

Accidental Falls↗
PubMed1997

Reattendance and complications in a randomised trial of prescribing strategies for sore throat: the medicalising effect of prescribing antibiotics.

OBJECTIVE: To assess the medicalising effect of prescribing antibiotics for sore throat. SETTING: 11 general practices in England. DESIGN: Randomised trial of three approaches to sore throat: a 10 day prescription of antibiotics, no antibiotics, or a delayed prescription if the sore throat had not started to settle after three days. PATIENTS: 716 patients aged 4 and over with sore throat and an abnormal physical sign: 84% had tonsillitis or pharyngitis. OUTCOME MEASURES: Number and rate of patients making a first return with sore throat, pharyngitis, or tonsillitis. Early returns (within two weeks) and complications (otitis media, sinusitis, quinsy). Outcomes were documented in 675 subjects (94%). RESULTS: Mean follow up time was similar (antibiotic group 1.07 years, other two groups 1.03 years). More of those initially prescribed antibiotics initially returned to the surgery with sore throat (38% v 27%, adjusted hazard ratio for return 1.39%, 95% confidence interval 1.03 to 1.89). Antibiotics prescribed for sore throat during the previous year had an additional effect (hazard ratio 1.69, 1.20 to 2.37). Longer duration of illness (> 5 days) was associated with increased return within six weeks (hazard ratio 2.90, 1.70 to 4.92). Prior attendance with upper respiratory conditions was also associated with increased reattendance. There was no difference between groups in early return (13/238 (5.5%) v 27/437 (6%)), or complications (2/236 (0.8%) v 3/434 (0.7%)). CONCLUSIONS: Complications and early return resulting from no or delayed prescribing of antibiotics for sore throat are rare. Both current and previous prescribing for sore throat increase reattendance. To avoid medicalising a self limiting illness doctors should avoid antibiotics or offer a delayed prescription for most patients with sore throat.

Adolescent↗
PubMed1997

Open randomised trial of prescribing strategies in managing sore throat.

OBJECTIVE: To assess three prescribing strategies for sore throat. DESIGN: Randomised follow up study. SETTING: 11 general practices in the South and West region. SUBJECTS: 716 patients aged 4 years and over with sore throat and an abnormal physical sign in the throat; 84% had tonsillitis or pharyngitis. Patients were randomised to three groups: prescription for antibiotics for 10 days (group 1,246 patients); no prescription (group 2,230 patients); or prescription for antibiotics if symptoms were not starting to settle after three days (group 3; 238 patients). MAIN OUTCOME MEASURES: Duration of symptoms; satisfaction and compliance with and perceived efficacy of antibiotics; time off school or work. Outcomes were documented in 582 subjects (81%). RESULTS: Median duration of antibiotic use differed significantly in the three groups (10 v 0 v 0 days, P < 0.001); 69% of patients in group 3 did not use their prescription. The proportion of patients better by day 3 did not differ significantly (37% v 35% v 30%, P = 0.28), nor did the duration of illness (median 4 v 5 v 5 days, P = 0.39), days off work or school (median 2 v 2 v 1, P = 0.13), or proportion of patients satisfied (96% v 90% v 93%, P = 0.09), although group 1 had fewer days of fever (median 1 v 2 v 2 days, P = 0.04). More patients in group 1 thought the antibiotics were effective (87% v 55% v 60%, P < 0.001) and intended coming to the doctor in future attacks (79% v 54% v 57%, P < 0.001). "Legitimation" of illness-to explain to work or school (60%) or family or friends (37%)-was an important reason for consultation. Patients who were more satisfied got better more quickly, and satisfaction related strongly to how well the doctor dealt with patient's concerns. CONCLUSION: Prescribing antibiotics for sore throat only marginally affects the resolution of symptoms but enhances belief in antibiotics and intention to consult in future when compared with the acceptable strategies of no prescription or delayed prescription. Psychosocial factors are important in the decision to see a general practitioner and in predicting the duration of illness.

Adolescent↗