1,957 research outputs found
Estimates of body sizes at maturation and at sex change, and the spawning seasonality and sex ratio of the endemic Hawaiian grouper (Hyporthodus quernus, F. Epinephelidae)
A case study of the reproductive biology of the endemic Hawaiian grouper or hapuâupuâu (Hyporthodus quernus) is presented as a model for comprehensive future studies of
economically important epinephelid groupers. Specimens were collected throughout multiple years (1978â81, 1992â93, and 2005â08) from most reefs and banks of the Northwestern
Hawaiian Islands. The absence of small males, presence of atretic oocytes and brown bodies in testes of mature males, and both developed ovarian and testicular tissues in the gonads of five transitional fish provided evidence of protogynous hermaphroditism. No small mature males were collected, indicating that Hawaiian grouper are monandrous
(all males are sex-changed females). Complementary microscopic criteria also were used to assign reproductive
stage and estimate median body sizes (L50) at female sexual maturity and at adult sex change from female to male. The L50 at maturation and at sex change was 580 ±8 (95% confidence interval [CI]) mm total length (TL) and 895 ±20 mm TL, respectively. The adult sex ratio was strongly female
biased (6:1). Spawning seasonality was described by using gonadosomatic indices. Females began ripening in the fall and remained ripe through April. A FebruaryâJune main spawning period that followed peak ripening was deduced from the proportion of females whose ovaries contained hydrated oocytes, postovulatory follicles, or both. Testes
weights were not affected by season; average testes weight was only about 0.2% of body weightâan order of magnitude smaller than that for ovaries that peaked at 1â3% of body
weight. The speciesâ reproductive life history is discussed in relation to its management
A qualitative perspective on multiple health behaviour change: views of smoking cessation advisors who promote physical activity
There are mixed views on whether smoking cessation advisors should focus only on quitting smoking or also promote simultaneous health behaviour changes (e.g. diet, physical activity), but no studies have qualitatively examined the views and vicarious experiences of such health professionals. Semi-structured interviews were conducted with 11 trained smoking cessation advisors who promote physical activity to their clients. The data were categorised into themes using thematic analysis supported by qualitative data analysis software. We report themes that were related to why advisors promote multiple health behaviour change and issues in timing. Physical activity could be promoted as a cessation aid and also as part of a holistic lifestyle change consistent with a non-smoker identity, thereby increasing feelings of control and addressing fear of weight gain. Multiple changes were promoted pre-quit, simultaneously and post-quit, and advisors asserted that it is important to focus on the needs and capabilities of individual clients when deciding how to time multiple changes. Also, suggesting that PA was a useful and easily performed cessation aid rather than a new behaviour (i.e. structured exercise that may seem irrelevant) may help some clients to avoid a sense of overload
Factors relating to the uptake of interventions for smoking cessation amongst pregnant women: a systematic review and qualitative synthesis
Introduction
The review had the aim of investigating factors enabling or discouraging the uptake of smoking cessation services by pregnant women smokers.
Methods
The literature was searched for papers relating to the delivery of services to pregnant or recently pregnant women who smoke. No restrictions were placed on study design. A qualitative synthesis strategy was adopted to analyse the included papers.
Results
Analysis and synthesis of the 23 included papers suggested ten aspects of service delivery that may have an influence on the uptake of interventions. These were: whether or not the subject of smoking is broached by a health professional; the content of advice and information provided; the manner of communication; having service protocols; follow-up discussion; staff confidence in their skills; the impact of time and resource constraints; staff perceptions of ineffectiveness; differences between professionals; and obstacles to accessing interventions.
Discussion
The findings suggest variation in practice between services and different professional groups, in particular regarding the recommendation of quitting smoking versus cutting down, but also in regard to procedural aspects such as recording status and repeat advice giving. These differences offer the potential for a pregnant woman to receive contradicting advice. The review suggests a need for greater training in this area and the greater use of protocols, with evidence of a perception of ineffectiveness/pessimism towards intervention amongst some service providers
A Robust Classification of Galaxy Spectra: Dealing with Noisy and Incomplete Data
Over the next few years new spectroscopic surveys (from the optical surveys
of the Sloan Digital Sky Survey and the 2 degree Field survey through to
space-based ultraviolet satellites such as GALEX) will provide the opportunity
and challenge of understanding how galaxies of different spectral type evolve
with redshift. Techniques have been developed to classify galaxies based on
their continuum and line spectra. Some of the most promising of these have used
the Karhunen and Loeve transform (or Principal Component Analysis) to separate
galaxies into distinct classes. Their limitation has been that they assume that
the spectral coverage and quality of the spectra are constant for all galaxies
within a given sample. In this paper we develop a general formalism that
accounts for the missing data within the observed spectra (such as the removal
of sky lines or the effect of sampling different intrinsic rest wavelength
ranges due to the redshift of a galaxy). We demonstrate that by correcting for
these gaps we can recover an almost redshift independent classification scheme.
From this classification we can derive an optimal interpolation that
reconstructs the underlying galaxy spectral energy distributions in the regions
of missing data. This provides a simple and effective mechanism for building
galaxy spectral energy distributions directly from data that may be noisy,
incomplete or drawn from a number of different sources.Comment: 20 pages, 8 figures. Accepted for publication in A
Bio-Creep in Non-Inferiority Clinical Trials
After a non-inferiority clinical trial, a new therapy may be accepted as effective, even if its treatment effect is slightly smaller than the current standard. It is therefore possible that, after a series of trials where the new therapy is slightly worse than the preceding drugs, an ineffective or harmful therapy might be incorrectly declared efficacious; this is known as âbio-creep.â Several factors may influence the rate at which bio-creep occurs, including the distribution of the effects of the new agents being tested and how that changes over time, the choice of active comparator, the method used to model the variability of the estimate of the effect of the active comparator, and changes in the effect of the active comparator from one trial to the next (violations of the constancy assumption). We performed a simulation study to examine which of these factors might lead to bio-creep and found that bio-creep was rare, except when the constancy assumption was violated
Modeling of Transitional Channel Flow Using Balanced Proper Orthogonal Decomposition
We study reduced-order models of three-dimensional perturbations in
linearized channel flow using balanced proper orthogonal decomposition (BPOD).
The models are obtained from three-dimensional simulations in physical space as
opposed to the traditional single-wavenumber approach, and are therefore better
able to capture the effects of localized disturbances or localized actuators.
In order to assess the performance of the models, we consider the impulse
response and frequency response, and variation of the Reynolds number as a
model parameter. We show that the BPOD procedure yields models that capture the
transient growth well at a low order, whereas standard POD does not capture the
growth unless a considerably larger number of modes is included, and even then
can be inaccurate. In the case of a localized actuator, we show that POD modes
which are not energetically significant can be very important for capturing the
energy growth. In addition, a comparison of the subspaces resulting from the
two methods suggests that the use of a non-orthogonal projection with adjoint
modes is most likely the main reason for the superior performance of BPOD. We
also demonstrate that for single-wavenumber perturbations, low-order BPOD
models reproduce the dominant eigenvalues of the full system better than POD
models of the same order. These features indicate that the simple, yet accurate
BPOD models are a good candidate for developing model-based controllers for
channel flow.Comment: 35 pages, 20 figure
Determinants of physical activity promotion by smoking cessation advisors as an aid for quitting: Support for the Transtheoretical Model
Objectives: Physical activity (PA) can reduce cigarette cravings and aid quitting but little is known about its promotion by smoking cessation advisors. This study aimed to: (1) determine the extent to which smoking cessation advisors promote PA; and (2) examine the relationship between PA promotion as a cessation aid and advisor characteristics and cognitions, within the Transtheoretical
Model (TM) framework.
Methods: Self-report surveys assessing PA promotion, TM variables, advisorsâ own PA levels and demographics were completed by 170 advisors in England and Scotland.
Results: Advisors reported spending 29 minutes promoting PA over a 6/7-week clinic. Those in later stages of readiness for promoting PA as a cessation aid and those spending more time promoting PA held more positive beliefs regarding pros and cons, self-efficacy, outcome efficacy and importance
of PA within smoking cessation. Time spent promoting PA and stage of readiness were strongly associated. There was a trend for the more physically active advisors to promote PA more often.
Conclusions: About half the advisors promoted PA and TM variables predicted this variability.
Practice Implications: PA promotion among smoking cessation advisors may be facilitated by enhancing self-efficacy, outcome efficacy and pro and con-beliefs related to PA promotion
Definition of valid proteomic biomarkers: a bayesian solution
Clinical proteomics is suffering from high hopes generated by reports on apparent biomarkers, most of which could not be later substantiated via validation. This has brought into focus the need for improved methods of finding a panel of clearly defined biomarkers. To examine this problem, urinary proteome data was collected from healthy adult males and females, and analysed to find biomarkers that differentiated between genders. We believe that models that incorporate sparsity in terms of variables are desirable for biomarker selection, as proteomics data typically contains a huge number of variables (peptides) and few samples making the selection process potentially unstable. This suggests the application of a two-level hierarchical Bayesian probit regression model for variable selection which assumes a prior that favours sparseness. The classification performance of this method is shown to improve that of the Probabilistic K-Nearest Neighbour model
Readiness to use physical activity as a smoking cessation aid: a multiple behaviour change application of the Transtheoretical Model among quitters attending Stop Smoking Clinics
Objective: Physical activity (PA) reduces cigarette cravings during smoking abstinence. However, little is known about quittersâ use of PA. This study aimed to: (1) determine the extent of quittersâ past and current use of PA as a cessation aid, while attempting to quit; (2) examine the relationship between use of PA and quitter characteristics and cognitions, within the Transtheoretical Model framework.
Methods: Self-report surveys were completed by 181 smokers attending Stop Smoking Services in England and Scotland.
Results: Twenty-two percent of quitters reported currently using PA to control their smoking, and 35% had used it during a previous quit attempt. Those in a more advanced stage of readiness for using PA as a cessation aid, held more positive beliefs regarding self-efficacy and outcome efficacy.
Conclusion: Quitters were more likely to use PA to help them quit when they had greater belief in their own ability to use PA and in the efficacy of PA to help them to quit, and were also meeting weekly PA targets for health.
Practice implications: Strategies by stop smoking advisors that aim to enhance client self-efficacy and outcome efficacy beliefs regarding PA as a cessation aid may help to increase the use of this behavioural strategy, since it seems that most quitters do not use PA
Water-use dynamics of an alien-invaded riparian forest within the summer rainfall zone of South Africa
In South Africa the invasion of riparian forests by alien trees has the potential to
affect the country's limited water resources. Tree water-use measurements
have therefore become an important component of recent hydrological studies.
It is difficult for South African government initiatives, such as the Working
for Water (WfW) alien clearing programme, to justify alien tree removal and
implement rehabilitation unless hydrological benefits are known.
The objective of this study was to investigate the water use (transpiration
rates) of a selection of introduced and indigenous tree species and quantify
the hydrological benefit that could be achieved through a suitable
rehabilitation programme. Consequently water use within a riparian forest in
the upper Mgeni catchment of KwaZulu-Natal in South Africa was monitored over
a 2-year period. The site consisted of an indigenous stand of eastern
mistbelt forest that had been invaded by Acacia mearnsii,
Eucalyptus nitens and Solanum mauritianum. The heat ratio
method of the heat pulse velocity (HPV) sap flow technique and the stem steady
state (SSS) techniques were used to measure the sap flow of a selection of
indigenous and introduced species. The indigenous trees at New Forest, South Africa, showed
clear seasonal trends in the daily sap flow rates varying from 8 to
25 L dayâ1 in summer (sap flow being directly proportional to tree
size). In the winter periods this was reduced to between 3 and
6 L dayâ1 when limited energy flux was available to drive the
transpiration process. The water use in the A. mearnsii and
E. grandis trees showed a slight seasonal trend, with a high flow
during the winter months in contrast to the indigenous species. The water use
in the understorey indicated that multi-stemmed species used up to
12 L dayâ1. Small alien trees (< 30 mm) A. mearnsii and S. mauritianum used up to 4 L dayâ1 each. The
total accumulated sap flow per year for the three individual A. mearnsii and E. grandis trees was 6548 and 7405 L aâ1
respectively. In contrast, the indigenous species averaged 2934 L aâ1, clearly demonstrating the higher water use of the
introduced species. After spatial upscaling, it was concluded that, at the
current state of invasion (21 % of the stand being alien species), the
stand used 40 % more water per unit area than if the stand were in a
pristine state. If the stand were to be heavily invaded at the same stem
density of the indigenous forest, a 100 % increase in water use would
occur over an average rainfall year.</p
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