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PubMed2003

Gender and educational differences in smoking initiation rates in Spain from 1948 to 1992.

BACKGROUND: The pattern of smoking initiation is of importance in understanding the prevalence of smoking and future trends in tobacco-related diseases. OBJECTIVE: To analyse trends of cigarette smoking initiation rates by sex and educational level in Spain. METHODS: Pooled data from the 1993, 1995 and 1997 Spanish National Health Interview Surveys were used (16,365 males and 17,478 females aged >15 years). The age and smoking status of each subject were reconstructed for five calendar periods (1948-1952, 1958-1962, 1968-1972, 1978-1982, 1988-1992). Age-specific (10 to 24 years old) smoking initiation rates were calculated for males and females, and according to level of education (high education: university and secondary school; low education: primary and less than primary). RESULTS: Among males, there was a trend towards earlier age at start of smoking and higher initiation rates between 1958 and 1982, and a subsequent decline in initiation rates, more apparent in males with a higher level of education. Smoking initiation among females was rare until the 1960s, and from the period 1968-1972 onwards a converging pattern with that of males was observed. Women with a higher level of education started smoking before women with low education, but this pattern changed over the period 1978-1982, with higher initiation rates among less educated women during the last period studied. CONCLUSIONS: These results help to characterize the tobacco epidemic in Spain, now at the end of stage 3. The observations are in agreement with diffusion-of-innovations theory and the social and economic changes from the 1960s onwards in Spain.

Adolescent↗
PubMed2003

Using patient-driven computers to provide cost-effective prevention in primary care: a conceptual framework.

This paper initially presents a rationale for the cost-effectiveness of using patient-driven computers in primary care services. It specifically defines the concepts of prevention and primary care, prior to outlining the advantages of promoting the implementation of prevention practices in primary care. It argues that greater use of computer technology represents one means of cost-effectively optimizing the integration of prevention into routine primary care, and identifies an apparent disjuncture between the potential of computers and the limited success with which attempts to integrate them into routine primary care services have been met, as evidenced in the published international literature. Among several possible explanations for this disjuncture, such as a possible lack of precision with which computers identify at-risk patients, perceived high costs associated with computers and physicians' concerns about the inflexibility and the more impersonal nature of computer interactions, is the apparent failure of researchers to utilize well designed and empirically tested models in the planning, implementation and evaluation of computerized care. An outline for such an approach, utilizing the Precede-Proceed model of health promotion planning and the Diffusion of Innovations theory, is presented.

British Columbia↗
PubMed2004

Improving tuberculosis therapy completion after jail: translation of research to practice.

Inmates have high rates of latent tuberculosis infection (LTBI), but inmates are often released early and do not complete therapy in the community. This study evaluated the translation of results from a randomized trial to improve therapy completion to usual care in a county jail using Rogers' Diffusion of Innovation theory. Inmates who received a single education in the randomized trial in 1998-1999 (study group) were compared to inmates educated by Jail Discharge Planners in 2002-2003 (usual care group). Outcomes were rates of completion of a visit to the TB clinic and completion of therapy. Subjects in the usual care group were significantly less likely to go to clinic in the 30-day period after release (relative risk 0.84, 95% confidence interval 0.75-0.95). The transfer of an educational protocol did not achieve results seen under study conditions, mostly because of implementation fidelity. The educational session in the usual care period for 81.0% of inmates took 5 min, as compared to 10-15 min during the randomized trial. Differences in personnel administering the protocol, training, high turnover and time available may also account for lower rates seen. Practical clinical trials should focus on the context of care as well as the intervention and should have participation by those who will be implementing results.

Adult↗
PubMed2006

A description of the social-ecological framework used in the trial of activity for adolescent girls (TAAG).

Social-ecological (SE) models are becoming more widely used in health behavior research. Applying SE models to the design of interventions is challenging because models must be tailor-made for each behavior and population, other theories need to be integrated into multi-level frameworks, and empirical research to guide model development is limited. The purpose of the present paper is to describe a SE framework that guided the intervention and measurement plans for a specific study. The trial of activity for adolescent girls (TAAG) is a multi-center study of interventions to reduce the decline of physical activity in adolescent girls. The TAAG framework incorporates operant learning theory, social cognitive theory, organizational change theory and the diffusion of innovation model in a multi-level model. The explicit and practical model developed for TAAG has already benefited the study and may have elements that can generalize to other health promotion studies.

Adolescent↗
PubMed2003

Do peer chart audits improve residents' performance in providing preventive care?

PURPOSE: One recommended method to evaluate residents' competence in practice-based learning and improvement is chart audit. This study determined whether residents improved in providing preventive care after a peer chart audit program was initiated. METHOD: Residents audited 1,005 charts and scored their peers on 12 clinical preventive services. The mean total chart audit scores were compared across five time blocks of the 45-month study. RESULTS: Residents' performance in providing preventive care initially improved significantly but declined in the last ten months. However, their performance remained significantly higher than at the beginning. CONCLUSIONS: By auditing their peers' charts, residents improved their own performance in providing preventive care. The diffusion of innovations theory may explain the prolonged implementation phase and problems in maintaining a chart audit program.

Analysis of Variance↗
PubMed2000

Burgers' turbulence with self-consistently evolved pressure

The Burgers' model of compressible fluid dynamics in one dimension is extended to include the effects of pressure back-reaction. The system consists of two coupled equations: Burgers' equation with a pressure gradient (essentially the one-dimensional Navier-Stokes equation) and an advection-diffusion equation for the pressure field. It presents a minimal model of both adiabatic gas dynamics and compressible magnetohydrodynamics. From the magnetic perspective, it is the simplest possible system which allows for "Alfvenization," i. e., energy transfer between the fluid and magnetic field excitations. For the special case of equal fluid viscosity and (magnetic) diffusivity, the system is completely integrable, reducing to two decoupled Burgers' equations in the characteristic variables v+/-v(sound) (v+/-v(Alfven)). For arbitrary diffusivities, renormalized perturbation theory is used to calculate the effective transport coefficients for forced "Burgerlence." It is shown that energy equidissipation, not equipartition, is fundamental to the turbulent state. Both energy and dissipation are localized to shocklike structures, in which wave steepening is inhibited by small-scale forcing and by pressure back reaction. The spectral forms predicted by theory are confirmed by numerical simulations.

Journal Article↗
PubMed2000

Long-time tracer diffusion of nonspherical brownian particles

The long-time tracer-diffusion properties of a nonspherical Brownian particle that interacts with a suspension of spherical particles are studied in terms of an idealized but nontrivial two-dimensional model system. For this system, the predictions of the generalized Langevin equation approach to tracer diffusion can be calculated, and compared with the (extrapolated) results of a computer simulation experiment. In the model, the nonspherical particle is represented by a rigid linear array of N(T) (=2 or 3) spherical particles with nearest-neighbor separation DeltaL. We calculate the long-time rotational and (transverse and longitudinal) translational diffusion coefficients. The theory is found to reproduce qualitatively and quantitatively the main features of the extrapolated results. Finally, we also present theoretical results that derive from still simpler approximate theoretical schemes.

Journal Article↗
PubMed2006

Application of the Hilbert space average method on heat conduction models.

We analyze closed one-dimensional chains of weakly coupled many level systems, by means of the so-called Hilbert space average method (HAM). Subject to some concrete conditions on the Hamiltonian of the system, our theory predicts energy diffusion with respect to a coarse-grained description for almost all initial states. Close to the respective equilibrium, we investigate this behavior in terms of heat transport and derive the heat conduction coefficient. Thus, we are able to show that both heat (energy) diffusive behavior as well as Fourier's law follows from and is compatible with a reversible Schrödinger dynamics on the complete level of description.

Journal Article↗
PubMed1987

Quality assurance: is it professional insurance?

Quality assurance (QA) is being hailed as a 'new frontier' of nursing. Its diffusion into nursing theory and practice in the United Kingdom is outlined. QA is not an alien import; favourable preconditions already existed. The systems-reasoning of the nursing process, which sprawned a plethora of models, each geared to the 'orderly' progression of stages, objectives and process, is resonant with the values and measurement techniques of QA. A major limitation of QA is that it downplays the organizational complexity of hospitals. Although QA is projected as being in the service of clients, its major impetus is concerned with professional self-defence, as regards other professions, the state and litigious clients. Further, QA enlisted by nursing strongly reproduces the ethos and logic of the dominant medical model; patients are 'objectified' as the technical products of production. The 'medical gaze' is now being joined with the 'nursing gaze'.

Consumer Behavior↗
PubMed2004

Nurses' use of online clinical evidence.

BACKGROUND: The 'information explosion' presents a significant challenge to the nursing profession. One way to assist access to information is to provide electronic information resources at the point of care. A large-scale survey of nurses working in the public health system in New South Wales, Australia, was undertaken as part of a 2-year evaluation of the Clinical Information Access Program (CIAP). This is a website which provides 24 hour, online access to a range of evidence sources at the point of care. AIM: This paper reports a study to investigate factors influencing nurses' use of online evidence available at the point of care and to examine differences between nurses in different roles. METHOD: Nurses from 65 randomly selected hospitals were surveyed. A convenience sample representing 25% of nursing staff at these hospitals was sought. Eighty-four per cent of the survey quota was met and 3128 questionnaires were completed and returned. RESULTS: The results showed that 58% of nurses had heard of the CIAP and, of those, 70% had used the website's resources. Senior nurses had greater awareness and use than others. The most frequent reasons for use were to fill a knowledge gap and for personal education. Lack of training was the most frequently cited reason for not using the website. Use of online evidence, particularly amongst senior staff, was higher than reported in previous studies. CONCLUSION: Use of online evidence was associated with nursing role, and with managerial and organizational support. Diffusion of innovation theory can help to explain some of the patterns observed. The use and impact of online evidence should be interpreted in the context of nursing practice and culture.

Adult↗
PubMed1982

Binding and screening by cations and the effect on exogenous NAD(P)H oxidation in Neurospora crassa mitochondria.

1. The uncoupled oxidation of exogenous NADH by mitochondria from Neurospora crassa has a pH optimum at 7.0. In the presence of EDTA (1 mM) the optimum is at pH 6.5; maximal inhibition (65%) occurs at pH 7.2. This is comparable to the results with higher plant mitochondria. 2. The corresponding pH optima for NADPH oxidation are 7.75 (control), 7.0 (+ EDTA) and 8.0 (effect of EDTA), respectively. NADPH oxidation is completely inhibited by EDTA at pH 8.0. These pH optima are all about 1 higher than observed in mitochondria from higher plants. 3. The inhibition of NADH oxidation by EDTA is shown to be due to the removal of Mg2+ bound to the mitochondrial membranes. 4. It is shown that 9-aminoacridine can be used to monitor the surface potential of the membranes of Neurospora mitochondria. 5. Cations stimulate NADH oxidation by Neurospora mitochondria in a manner consistent with the theory of the diffuse layer. Quantitatively, the results suggest that Neurospora mitochondria contain fewer charges per mass of protein than Jerusalem artichoke (Helianthus tuberosus) mitochondria but more than mitochondria from Arum maculatum spadices. 6. A good correlation is found between the effect of La3+ on the fluorescence of 9-aminoacridine in the presence of mitochondria and on the oxidation of NADH by the mitochondria. La3+ has different effects on mitochondria from Neurospora, Jerusalem artichoke tubers and Arum spadices. THe results indicate that the fluorescence of 9-aminoacridine can be used to monitor binding sites on biological membranes.

Aminacrine↗
PubMed1989

Transcutaneous oxygen potentials in venous disease.

Abnormal levels of transcutaneous tissue oxygen tension (TcPO2) have been reported in venous disease but the most appropriate application of the technique to the study of venous disease is not clear. Patients with mild (superficial varicosities) and severe venous disease (ulcers and/or skin changes) and normal controls were studied. Four variables derived by measurement of TcPO2 were used for comparison between groups. The peak postischaemic response was reduced markedly in patients with severe venous disease and may be the most appropriate way of applying TcPO2 measurements to investigation of venous disease. The findings support the theory that a diffusion block to oxygen exists in severe venous disease.

Blood Gas Monitoring, Transcutaneous↗
PubMed1987

Fluid and protein fluxes across small and large pores in the microvasculature. Application of two-pore equations.

Treating the blood-tissue barrier as a two-pore membrane the separate fluid and solute fluxes occurring across 'small pores' and 'large pores' were modelled in continuous capillaries employing two-pore equations for the calculations together with the non-linear flux equation and theories for restricted diffusion and for the reflection coefficient (sigma). The two-pore equations derived proved useful for analyses of transvascular protein flux data obtained at low as well as at high filtration rates. These equations were applied to lymphatic protein flux data from dog paw (Renkin et al. 1977a, b) and to tracer albumin uptake data from rat skeletal muscle (Rippe et al. 1979). For both sets of data the small- and large-pore radii became closely similar, 44 vs. 45 A and 240 vs. 225 A, which also holds for the large-pore fractions of hydraulic conductivity (0.097 vs. 0.056). The main result of this analysis is that the passage of macromolecules normally occurring across the microvascular walls is almost entirely convective, and hence, dependent on the transmural hydrostatic and oncotic pressure gradients and on the hydraulic conductivity. For example, 75-90% of the transvascular passage of albumin was found to be due to convection through large pores at normal lymph flows, the remaining portion being mainly due to diffusion across small pores. Solutes larger than albumin were almost exclusively transported by convection across large pores. Two-pore heterogeneity was found to explain the previously observed variations of the apparent overall large solute diffusion capacity (PSapp) and the overall reflection coefficient (sigma f) with filtration rate and also previous overestimations of PS. Furthermore, the present results were not compatible with protein transport across any 'non-hydraulically conductive capillary pathways' as previously postulated from the lymphatic protein flux data analysed here (Renkin 1985).

Albumins↗
PubMed1991

Upper and lower bounds on capillary permeability ratios of Cr-EDTA to cyanocobalamin in rat hindquarters.

The single injection indicator dilution technique, often used for assessing capillary permeability, was employed for estimations of the equivalent pore radius of skeletal muscle microvessels according to the theory of restricted diffusion. There are, however, certain important sources of error that must be considered in order to allow conclusions regarding the degree of restricted diffusion. In this study, we have recalculated previously published data in order to minimize the effect of heterogeneity of the second kind, i.e. a transit-time dependence of the fractional extraction values. The method used makes it possible to calculate reliable intervals of confidence for the permeability surface area products, and hence for the permeability surface area product-ratios (and equivalent pore radius), taking into account the maximal theoretical impact of back diffusion on measured extraction data. After correction for transit-time dependent effects of heterogeneity, the permeability surface area product-ratio of Cr-EDTA to cyanocobalamin (vit. B12) from 48 measurements in eight rats was found to have a theoretical 'upper bound' of 2.63 +/- 0.06 and a lower bound of 2.10 +/- 0.07, corresponding to an equivalent pore radius of 60 to 109 A. This minimum pore radius estimate was even further reduced by corrections for plasma flow dependent reductions in overall extraction fraction (heterogeneity of the first kind) to 45 A, whereas the upper bound on pore radius was reduced to 60 A. These data strongly support the presence of marked restricted diffusion of small solutes in the maximally vasodilated rat hindquarter microvasculature.

Animals↗
PubMed1976

Two components of the calcium current in the egg cell membrane of the tunicate.

The Ca current of the egg cell membrane of a certain tunicate, Halocynthia roretzi Drasche, was studied by the voltage-clamp technique. 2. The Ca current in the standard artificial sea water (ASW) was produced at the critical membrane potential of -10 mV after inactivating the Na current by conditioning depolarization, -30 to -15 mV. The Ca current was abolished by replacing Ca in ASW with Mg2+ or Mn2+. The Ca current was not significantly influenced by replacing Na in ASW with choline or Cs. 3. The relation of Ca current to the external Ca concentration was a monotonously increasing function, but was not linear. The current tended to saturate above 50 mM-Ca. In 100 mM-Ca ASW, the maximum peak inward current of Ca ranged from 1 to 7 X 10(-9) A. 4. The kinetics of Ca current was accurately analysed because of the small contribution of K outward current and was found to be relatively slow in comparison with the Na current. The peak time and the half-decay time of the maximum Ca current at about 25 mV were about 25 and 100 msec respectively in 100 mM-Ca ASW at 15 degrees C. 5. Addition of 20 mM-Co2+ to 100 mM-Ca ASW reduced Ca current to one fourth and 1 mM-La3+ to 100 mM-Ca ASW abolished the current. 6. Sr and Ba could substitute for Ca in Ca channels. The selectivity ratios for the 'Ca channels's were Ca (1-00):Sr(1-17):Ba(0-71) at a potential level of +40 mV. The Ca current in the egg cell membrane appeared to be essentially the same as the Ca current in the common excitable membranes, such as the crustacean muscle fibre. 7. The polyvalent cations including Ca ion and monovalent H+ ion showed the stabilizing effect upon both Na and Ca currents, by shifting V-I relations along the voltage axis. From the prediction of a theory of the diffuse double layer, the shift in the V-I relation induced by those cations should be directly related to their binding powers to the membrane. Thus, the sequence of the binding powers was inferred as H+ greater than La3+ greater than Co2+ greater than Mn2+ greater than Ca2+ greater than Sr2+ larger than or equal to Ba2+ greater than Mg2+. 9. In Na-free ASW, such as isotonic Ca ASW, Ca current was composed of two components. The one component was the Ca current described in 1 to 6. The other was also dependent upon the external Ca concentration, but showed the more negative critical membrane potential and the faster kinetics. It was concluded that this component should be the Ca current through Na channels. 10. The selectivity among Ca, Sr and Ba for 'Ca' current through 'Na channels' was significantly different from that of 'Ca' current through 'Ca channels', being Ca greater than Sr larger than or equal to Ba = 0.

Animals↗
PubMed1975

Effect of histamine on microvasculature of isolated dog gracilis muscle.

Isogravimetric capillary pressure (Pci), capillary filtration coefficient (CFC), and plasma protein concentration were measured before and during adminisistration of histamine in an isolated, independently perfused canine gracilis muscle. Histamine produced an average decrease in Pci of 14.1 mmHg, an increase in CFC of 36-fold, and an increased rate of plasma protein escape of at least 24-fold. These results suggest that histamine reduces the reflection coefficient for protein at the capillary wall and are consistent with predictions of the theory of restricted diffusion assuming that 1-2.5% of available pores increase in radious from 40 to 240 A.

Animals↗
PubMed1990

Chemical events during tooth dissolution.

Information on chemical changes during enamel dissolution has been collected from investigations on hydroxyapatite solubility, enamel solubility, artificial lesion formation, and natural caries. Although hydroxyapatite and enamel will ultimately dissolve in acid or during caries, compositional changes also occur. Most notably, there is a preferential dissolution of calcium, both from hydroxyapatite and from enamel, and of carbonate and magnesium from enamel. Root dentin yields substantial amounts of magnesium on acid attack. Fluoride may be involved in surface zone formation during attack, but an additional theory of coupled diffusion is described. Calcium-deficient mineral is produced during an acid attack, and this has lattice parameters and solubility behavior different from those of stoichiometric material. The interaction of fluoride produces a more stable lattice, resisting dissolution and favoring accretion, and tending to counteract the effects of carbonate and magnesium in forming mineral. The provision of fluoride, albeit at low levels, in plaque fluid is seen as being important in maintaining the net integrity of the tooth. More information is also needed on the role of the organic phase in tooth structures during caries and acid attack.

Dental Caries↗
PubMed2005

Randomized trial testing a worksite sun protection program in an outdoor recreation industry.

Health communication campaigns intended to reduce chronic and severe exposure to ultraviolet radiation in sunlight and prevent skin cancer are a national priority. Outdoor workers represent an unaddressed, high-risk population. Go Sun Smart (GSS), a worksite sun safety program largely based on the diffusion-of-innovations theory, was evaluated in a pair-matched, group-randomized, pretest-posttest controlled design enrolling employees at 26 ski areas in Western North America. Employees at the intervention ski areas were more aware of GSS (odds ratio [OR] = 8.27, p < .05) and reported less sunburning (adjusted OR = 1.63, p < .05) at posttest than employees at the control areas. A dose response was evident (OR = 1.46, p < .05) with greater observed program implementation associated with fewer sunburns among employees. Program awareness per se was not predictive (p > .05) of reduced sunburning in a mediational analysis. Analyses of nonrespondents, including intent-to-treat analyses, further supported the success of GSS.

Adolescent↗