Biomedical subjects

R West

Publications and source records attributed to R West.

At least 19 recordsLinked to original sources

PubMed2007

The lakes of Titan.

The surface of Saturn's haze-shrouded moon Titan has long been proposed to have oceans or lakes, on the basis of the stability of liquid methane at the surface. Initial visible and radar imaging failed to find any evidence of an ocean, although abundant evidence was found that flowing liquids have existed on the surface. Here we provide definitive evidence for the presence of lakes on the surface of Titan, obtained during the Cassini Radar flyby of Titan on 22 July 2006 (T16). The radar imaging polewards of 70 degrees north shows more than 75 circular to irregular radar-dark patches, in a region where liquid methane and ethane are expected to be abundant and stable on the surface. The radar-dark patches are interpreted as lakes on the basis of their very low radar reflectivity and morphological similarities to lakes, including associated channels and location in topographic depressions. Some of the lakes do not completely fill the depressions in which they lie, and apparently dry depressions are present. We interpret this to indicate that lakes are present in a number of states, including partly dry and liquid-filled. These northern-hemisphere lakes constitute the strongest evidence yet that a condensable-liquid hydrological cycle is active in Titan's surface and atmosphere, in which the lakes are filled through rainfall and/or intersection with the subsurface 'liquid methane' table.

Journal Article↗

PubMed2006

Prevalence, diagnosis and relation to tobacco dependence of chronic obstructive pulmonary disease in a nationally representative population sample.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is the fourth most common cause of death worldwide. It is caused primarily by cigarette smoking. Given its importance, it is remarkable that reliable national prevalence data are lacking for most countries. This study provides estimates of the national prevalence of COPD in England, the extent of under-detection of the disorder, and patterns of cigarette smoking, dependence, and motivation to stop smoking in those with the disease. METHODS: Data from 8215 adults over the age of 35 who participated in the Health Survey for England were analysed. Information was obtained on self-reported and cotinine validated smoking status, cigarette dependence, motivation to stop smoking, COPD defined by spirometry using joint American Thoracic Society and European Respiratory Society criteria, and self-reports of diagnosis with respiratory disorders. RESULTS: Spirometry-defined COPD was present in 13.3% (95% CI 12.6 to 14.0) of participants, over 80% of whom reported no respiratory diagnosis. Even among people with severe or very severe COPD by spirometric assessment, only 46.8% (95% CI 39.1 to 54.6) reported any diagnosed respiratory disease. A total of 34.9% (95% CI 32.1 to 37.8) of people with spirometry-defined COPD were smokers compared with 22.4% (95% CI 21.4 to 23.4) of those without, and smoking prevalence increased with disease severity. Smokers with spirometry-defined COPD were more cigarette dependent but had no greater desire to quit than other smokers. CONCLUSION: COPD is common among adults in England and is predominantly undiagnosed. In smokers it is associated with higher degrees of cigarette dependence but not with a greater motivation to stop smoking.

Adult↗

PubMed2006

Titan Radar Mapper observations from Cassini's T3 fly-by.

Cassini's Titan Radar Mapper imaged the surface of Saturn's moon Titan on its February 2005 fly-by (denoted T3), collecting high-resolution synthetic-aperture radar and larger-scale radiometry and scatterometry data. These data provide the first definitive identification of impact craters on the surface of Titan, networks of fluvial channels and surficial dark streaks that may be longitudinal dunes. Here we describe this great diversity of landforms. We conclude that much of the surface thus far imaged by radar of the haze-shrouded Titan is very young, with persistent geologic activity.

Journal Article↗

PubMed2006

The sand seas of Titan: Cassini RADAR observations of longitudinal dunes.

The most recent Cassini RADAR images of Titan show widespread regions (up to 1500 kilometers by 200 kilometers) of near-parallel radar-dark linear features that appear to be seas of longitudinal dunes similar to those seen in the Namib desert on Earth. The Ku-band (2.17-centimeter wavelength) images show approximately 100-meter ridges consistent with duneforms and reveal flow interactions with underlying hills. The distribution and orientation of the dunes support a model of fluctuating surface winds of approximately 0.5 meter per second resulting from the combination of an eastward flow with a variable tidal wind. The existence of dunes also requires geological processes that create sand-sized (100- to 300-micrometer) particulates and a lack of persistent equatorial surface liquids to act as sand traps.

Extraterrestrial Environment↗

PubMed2006

Enceladus' water vapor plume.

The Cassini spacecraft flew close to Saturn's small moon Enceladus three times in 2005. Cassini's UltraViolet Imaging Spectrograph observed stellar occultations on two flybys and confirmed the existence, composition, and regionally confined nature of a water vapor plume in the south polar region of Enceladus. This plume provides an adequate amount of water to resupply losses from Saturn's E ring and to be the dominant source of the neutral OH and atomic oxygen that fill the Saturnian system.

Atmosphere↗

PubMed2006

Cassini observes the active south pole of Enceladus.

Cassini has identified a geologically active province at the south pole of Saturn's moon Enceladus. In images acquired by the Imaging Science Subsystem (ISS), this region is circumscribed by a chain of folded ridges and troughs at approximately 55 degrees S latitude. The terrain southward of this boundary is distinguished by its albedo and color contrasts, elevated temperatures, extreme geologic youth, and narrow tectonic rifts that exhibit coarse-grained ice and coincide with the hottest temperatures measured in the region. Jets of fine icy particles that supply Saturn's E ring emanate from this province, carried aloft by water vapor probably venting from subsurface reservoirs of liquid water. The shape of Enceladus suggests a possible intense heating epoch in the past by capture into a 1:4 secondary spin/orbit resonance.

Extraterrestrial Environment↗

PubMed2006

Awareness of mouth cancer in Great Britain.

OBJECTIVE: There are more than 2,000 new cases of mouth cancer each year in Britain. Early detection is important yet little is known about population awareness of this disease and ability to recognise early signs, particularly among high risk groups. This study aimed to address this issue. METHODS: Data were collected by means of household survey. A total of 3,384 adults were questioned using a national probability sample. Respondents provided information on demographic characteristics, smoking status, and frequency of alcohol use. They were asked whether they had heard of mouth cancer. Their knowledge of early signs and risk factors was assessed. RESULTS: Whereas 95.6% of respondents said they had heard of mouth cancer, their awareness of early signs was low; for example, only 33.8% recognised that white patches in the mouth were a sign. The large majority understood that smoking and chewing tobacco were risk factors (84.7% and 80.1% respectively) but only 19.4% recognised alcohol use as a risk factor. In multiple logistic regression analyses controlling for relevant demographic factors, smokers and those with more frequent alcohol consumption were less likely to recognise early signs. CONCLUSIONS: Awareness of early signs of mouth cancer is low and lower in people who as a result of their behaviour are at higher risk. There is a need to raise awareness in those at most risk.

Adult↗

PubMed2006

Levels of toxins in oral tobacco products in the UK.

OBJECTIVE: This study examined the constituents of smokeless tobacco products available in the UK and compared them with products available in India, Sweden, and the USA. METHODS: Seven UK brands of smokeless tobacco, including a tooth cleaning powder, and four international brands of smokeless tobacco were tested for a range of toxins and known carcinogens, such as tobacco specific N-nitrosamines (TSNA), as well as nicotine availability. RESULTS: Ten of the 11 brands tested had detectable levels of tobacco specific nitrosamines, which are proven carcinogens, and levels varied 130-fold. All had detectable levels of benzo(a)pyrene, another proven carcinogen (with around 175-fold variation) and several toxic metals (with nearly 150-fold variation). Nicotine availability varied in the UK products from 0.1 mg/g to 63.2 mg/g. All the tobacco products tested are likely to be hazardous to users' health, but the data indicate that it should be possible to reduce key toxins to non-detectable levels. CONCLUSIONS: Smokeless tobacco products should be regulated and standards set for maximum levels of toxins and carcinogens.

Asia↗

PubMed2006

Vulnerability to smoking after trying a single cigarette can lie dormant for three years or more.

OBJECTIVE: To examine the development of smoking behaviour among adolescents who, at age 11, had tried cigarettes just once. DESIGN: A five-year prospective study. SETTING: 36 schools in South London, England. SUBJECTS: A socioeconomically and ethnically diverse sample of students completed questionnaires annually from age 11-16. A total of 5863 students took part, with an annual response rate ranging from 74-85%. 2041 (35%) provided smoking status data every year. MAIN OUTCOME MEASURES: Current smoking (smoking sometimes or more often) for the first time. Cotinine assays provided biochemical verification of smoking status. RESULTS: Students who at age 11 reported having tried smoking cigarettes just once (n = 260), but were not smoking at the time, were more likely to take-up smoking at a later age than those that had not tried smoking (n = 1719), even after a gap of up to three years of not smoking. The odds of starting to smoke at age 14 were 2.1 times greater (95% confidence interval 1.2 to 3.5) in the age 11 "one time triers" than the "non-triers", even once sex, ethnicity, deprivation, parental smoking and conduct disorder were adjusted for. CONCLUSIONS: This is the first clear demonstration of a "sleeper effect" or period of dormant vulnerability. Our findings have implications for understanding the development of cigarette use and for policies to reduce smoking in young people. Preventing children from trying even one cigarette may be important, and the design of interventions should recognise adolescents who have smoked just once, several years previously, as potentially vulnerable to later smoking uptake.

Adolescent↗

PubMed2005

Rain, winds and haze during the Huygens probe's descent to Titan's surface.

The irreversible conversion of methane into higher hydrocarbons in Titan's stratosphere implies a surface or subsurface methane reservoir. Recent measurements from the cameras aboard the Cassini orbiter fail to see a global reservoir, but the methane and smog in Titan's atmosphere impedes the search for hydrocarbons on the surface. Here we report spectra and high-resolution images obtained by the Huygens Probe Descent Imager/Spectral Radiometer instrument in Titan's atmosphere. Although these images do not show liquid hydrocarbon pools on the surface, they do reveal the traces of once flowing liquid. Surprisingly like Earth, the brighter highland regions show complex systems draining into flat, dark lowlands. Images taken after landing are of a dry riverbed. The infrared reflectance spectrum measured for the surface is unlike any other in the Solar System; there is a red slope in the optical range that is consistent with an organic material such as tholins, and absorption from water ice is seen. However, a blue slope in the near-infrared suggests another, unknown constituent. The number density of haze particles increases by a factor of just a few from an altitude of 150 km to the surface, with no clear space below the tropopause. The methane relative humidity near the surface is 50 per cent.

Atmosphere↗

PubMed2005

Complications of diagnostic cardiac catheterisation: results from a confidential inquiry into cardiac catheter complications.

OBJECTIVES: To estimate the frequency and nature of complications in patients undergoing diagnostic cardiac catheterisation and to assess time trends in complications since the introduction of a voluntary cooperative audit. METHODS: Cardiac centres undertaking diagnostic cardiac catheterisation in England and Wales during the 10 years 1990-9 were invited to join the study. Each participating centre reported numbers of patients catheterised each month and details of complications and deaths as they occurred. Complication rates were calculated for the main diagnostic procedures and for each participating hospital and time trends in complications were examined. RESULTS: 41 cardiac centres contributed. 211 645 diagnostic procedures in adults and 7582 paediatric procedures were registered. The majority (87%) of diagnostic catheter studies in adults were left heart studies with coronary arteriography. The overall complication rate for adult procedures was 7.4/1000, with mortality at 0.7/1000; for paediatric procedures the complication rate was similar but mortality rather higher. Complication rates varied between centres but there was little association with caseload. Time trends across the decade showed both complication and mortality decreasing; from 9.5 to 5.8/1000 and from 1.4 to 0.4/1000, respectively. CONCLUSION: Complication rates of diagnostic catheterisation are low but neither negligible nor irreducible. While voluntary audit of cardiac catheter complications is useful and inexpensive, there is a clear need to establish a formal reporting system in all cardiac catheter laboratories, with clear definitions of reportable complications.

Adult↗

PubMed2005

Cassini radar views the surface of Titan.

The Cassini Titan Radar Mapper imaged about 1% of Titan's surface at a resolution of approximately 0.5 kilometer, and larger areas of the globe in lower resolution modes. The images reveal a complex surface, with areas of low relief and a variety of geologic features suggestive of dome-like volcanic constructs, flows, and sinuous channels. The surface appears to be young, with few impact craters. Scattering and dielectric properties are consistent with porous ice or organics. Dark patches in the radar images show high brightness temperatures and high emissivity and are consistent with frozen hydrocarbons.

Atmosphere↗

PubMed2005

Cassini Imaging Science: initial results on Saturn's atmosphere.

The Cassini Imaging Science Subsystem (ISS) began observing Saturn in early February 2004. From analysis of cloud motions through early October 2004, we report vertical wind shear in Saturn's equatorial jet and a maximum wind speed of approximately 375 meters per second, a value that differs from both Hubble Space Telescope and Voyager values. We also report a particularly active narrow southern mid-latitude region in which dark ovals are observed both to merge with each other and to arise from the eruptions of large, bright storms. Bright storm eruptions are correlated with Saturn's electrostatic discharges, which are thought to originate from lightning.

Atmosphere↗

PubMed2005

Cassini Imaging Science: initial results on Phoebe and Iapetus.

The Cassini Imaging Science Subsystem acquired high-resolution imaging data on the outer Saturnian moon, Phoebe, during Cassini's close flyby on 11 June 2004 and on Iapetus during a flyby on 31 December 2004. Phoebe has a heavily cratered and ancient surface, shows evidence of ice near the surface, has distinct layering of different materials, and has a mean density that is indicative of an ice-rock mixture. Iapetus's dark leading side (Cassini Regio) is ancient, heavily cratered terrain bisected by an equatorial ridge system that reaches 20 kilometers relief. Local albedo variations within and bordering Cassini Regio suggest mass wasting of ballistically deposited material, the origin of which remains unknown.

Extraterrestrial Environment↗

PubMed2005

Cassini Imaging Science: initial results on Saturn's rings and small satellites.

Images acquired of Saturn's rings and small moons by the Cassini Imaging Science Subsystem (ISS) during the first 9 months of Cassini operations at Saturn have produced many new findings. These include new saturnian moons; refined orbits of new and previously known moons; narrow diffuse rings in the F-ring region and embedded in gaps within the main rings; exceptionally fine-scale ring structure in moderate- to high-optical depth regions; new estimates for the masses of ring-region moons, as well as ring particle properties in the Cassini division, derived from the analysis of linear density waves; ring particle albedos in select ring regions; and never-before-seen phenomena within the rings.

Journal Article↗

PubMed2005

Relapse prevention interventions for smoking cessation.

BACKGROUND: Several treatments can help smokers make a successful quit attempt, but many initially successful quitters relapse over time. There are interventions designed to help prevent relapse. OBJECTIVES: To assess whether specific interventions for relapse prevention reduce the proportion of recent quitters who return to smoking. SEARCH STRATEGY: We searched the Cochrane Tobacco Addiction group trials register in September 2004 for studies mentioning relapse prevention or maintenance in title, abstracts or keywords. SELECTION CRITERIA: Randomized or quasi-randomized controlled trials of relapse prevention interventions with a minimum follow up of six months. We included smokers who quit on their own, or were undergoing enforced abstinence, or who were participating in treatment programmes. We included trials that compared relapse prevention interventions to a no intervention control, or that compared a cessation programme with additional relapse prevention components to a cessation programme alone. DATA COLLECTION AND ANALYSIS: Studies were screened and data extracted by one author and checked by a second. Disagreements were resolved by discussion or referral to a third author. MAIN RESULTS: Forty studies met inclusion criteria, but were heterogeneous in terms of populations and interventions. We considered studies that randomized abstainers separately from studies that randomized participants prior to their quit date. We detected no benefit of brief and 'skills-based' relapse prevention interventions for women who had quit smoking due to pregnancy, or for smokers undergoing a period of enforced abstinence. We also failed to detect significant effects in trials in other smokers who had quit on their own or with a formal programme. Amongst trials recruiting smokers and evaluating the effect of additional relapse prevention components we also found no evidence of benefit in any subgroup. We did not find that providing training in skills thought to be needed for relapse avoidance reduced relapse, but most studies did not use experimental designs best suited to the task, and had limited power to detect expected small differences between interventions. AUTHORS' CONCLUSIONS: At the moment there is insufficient evidence to support the use of any specific intervention for helping smokers who have successfully quit for a short time to avoid relapse. The verdict is strongest for interventions focusing on identifying and resolving tempting situations, as most studies were concerned with these. There is very little research available regarding other approaches. Until more evidence becomes available it may be more efficient to focus resources on supporting the initial cessation attempt rather than on additional relapse prevention efforts.

Behavior Therapy↗

PubMed2005

General practitioners' views on and referral to NHS smoking cessation services.

OBJECTIVES: Increasing the rate of smoking cessation remains a major public health goal. To help achieve this in the UK, National Health Service (NHS) smoking cessation services have been established to provide treatment for smokers wanting help with stopping. Referrals from general practitioners (GPs) are crucial to the success of these clinics. This study aimed to assess English GPs' self-reported interactions with, and attitudes towards, their local smoking cessation services. STUDY DESIGN: Postal survey assessing the attitudes of GPs in England towards, and formal interactions with, NHS smoking cessation services. METHODS: A questionnaire was posted to a random sample of 544 GPs in England (response rate 63%). GPs' self-reported interactions with smoking cessation services and their attitudes towards these clinics were assessed. GPs were also asked what factors determined whether they prescribed nicotine-replacement therapy (NRT) and Buproprion (Zyban), and what was the extent and nature of their smoking cessation interventions with their patients. RESULTS: Most GPs (94%) reported that they were aware of the specialist smoking cessation service in their area. Seventy percent of GPs supported the continuation of current funding for specialist smoking cessation services. Seventy percent reported that they referred patients to these services, and 55% had staff within their practices trained as community smoking cessation advisors. Most GPs (79%) reported 'clinical need' as a determinant of whether they prescribed NRT/Zyban, and a few GPs cited 'budgetary constraints' as a factor (15%). Ninety-eight percent of GPs reported that they record smoking status when new patients join their practice, and they advise smokers to stop 'at least every now and then'. CONCLUSIONS: GPs support the existence and continuation of specialist smoking cessation services, and most reported that they refer patients to them. Virtually every GP reported that they record smoking status when new patients join their practice, and they advise smokers to stop 'at least every now and then'.

Adult↗

PubMed2005

Do clinical trials improve quality of care? A comparison of clinical processes and outcomes in patients in a clinical trial and similar patients outside a trial where both groups are managed according to a strict protocol.

BACKGROUND: The conventional view that participants in randomised controlled trials sacrifice themselves for the good of future patients is challenged by increasing evidence to suggest that individual patients benefit from participation in trials. OBJECTIVE: To test the hypothesis that trial participants receive higher quality care and, as a consequence, have better outcomes than patients receiving guideline driven routine care. METHODS: Retrospective comparative study of 408 women with pre-eclampsia all managed according to a strict protocol. Trial participants were 86 women who participated in a multicentre randomised controlled trial of magnesium sulphate for the treatment of pre-eclampsia (Magpie Trial); 322 non-participants formed the control group. Indicators of the process of care and clinical outcomes were compared between the two groups. RESULTS: Trial participants were significantly more likely to have received daily blood tests (odds ratio (OR) 6.82, 95% CI 1.62 to 28.72) and had their respiration rate measured hourly (OR 3.42, 95% CI 1.69 to 6.92) than control patients. There were no significant differences in other markers of clinical process and no significant difference in clinical outcomes. CONCLUSION: This study shows minor differences in process markers and no difference in clinical outcomes between patients in a clinical trial and patients receiving protocol driven care. The benefits of improved clinical care that have previously been associated with being in a trial may be explained by the use of clear clinical protocols. In routine practice, patients may be well advised to insist on treatment as part of a protocol.

Clinical Protocols↗