475 research outputs found
A meta-analysis of economic diplomacy and its effect on international economic flows
This meta-analysis deals with 29 empirical studies on the trade and investment impact of economic diplomacy (embassies, consulates and other diplomatic facilities, investment and export promotion offices, trade and state visits). The meta-regression results suggest that the significance of the coefficient of economic diplomacy is more pronounced when studies use embassies as an explanatory variable as compared to studies using consulates, trade missions, state visits and export promotion agencies. If the primary dependant variable under investigation is exports one may also expect to find more significant coefficients then in an otherwise similar regression explaining the relation between economic diplomacy and imports, total trade or foreign direct investment. Furthermore empirical design factors play a role in the reported results of the studies we reviewed. Studies based on a single country will in general show lower significance
Regional variation in angioplasty practice in the United States: A report from the Hirulog angioplasty study
Pla general de la font anomenada Homenatge
al poble, ubicada a la plaça Molina. A la part
superior de la font, a cada costat, hi ha un escut cisellat. Sota un d'aquests es troba la frase Gratitud al Ayuntamiento.Realitzada en pedra abans de 1874
Regional myocardial perfusion : experimental and clinical studies in patients with coronary artery disease
Coronary artery disease has become a world wide medical problem. There is an overwhelming association between coronary atherosclerosis, angina pectoris, acute myocardial infarction and sudden death. The narrowing of coronary arteries is thought to damage the heart by limiting appropriate changes in coronary blood flow and by causing myocardial ischemia. This thesis attempts to examine the coronary circulation in patients who present with chest pain with and without coronary artery disease. One of the aims of this thesis is to validate the use of a short-lived radionuclide to study changes in regional myocardial perfusion. This technique has been applied in clinical medicine in an attempt to describe the disturbances of regional myocardial perfusion that occur in patients with coronary artery disease. These disturbances of perfusion have been related to the patients' symptoms, the electrocardiogram and the stenosed arteries seen in the arteriogram. Krypton-81m in solution is an inert freely diffusible gas (half-life 13 seconds) which emits a single 190 kev gamma ray. This tracer, a special catheter and a gamma camera have been developed in experiments to measure changes in regional myocardial perfusion. The systematic and rand-Om errors of the method have been defined in experiments. The results show that the mixing and delivered arterial concentration of krypton-81m are stable within a useful physiological range of changes in heart rate, blood pressure and coronary blood flow. Correlations with a reference technique have shown that the method can measure changes in regional myocardial perfusion between O and 3 ml/ml/min. The invasive method, the planar imaging and the need for calibration with washout at high levels of perfusion are investigated and described as limitations that must be considered. Eighty patients presenting with chest pain have been investigated by routine clinical methods, precordial mapping of the electrocardiogram during exercise and coronary arteriography. Changes in regional myocardial perfusion at rest and during atrial pacing has been measured using krypton-81m. The results have shown that stable mixing and delivered arterial concentration of krypton-81m can be achieved in the patients. Fifteen patients with negative exercise tests all demonstrated uniform increases in regional myocardial perfusion with pacing. The remaining 65 patients with positive exercise tests and significant coronary artery disease all showed both regional increases and decreases in myocardial perfusion during atrial pacing. In 16 of the 65 patients the jeopardized segment of ventricular myocardium showed significant increases in perfusion during the first 4 to 7 minutes of pacing. Th e increase stopped and regional perfusion in the affected segment then decreased progressively until the pacing was stopped. In 23 of the 65 patients the affected segment showed no changes in perfusion for 5 to 7 minutes of atrial pacing and then showed progressive decreases in regional myocardial perfusion until the pacing was stopped. Finally, in 26 of the 65 patients the affected segment showed immediate and progressive decreases of regional myocardial perfusion starting with the commencement of atrial pacing. In all the patients with disturbed perfusion ST segment depression in the electrocardiogram appeared after (140 ± 14 sec) the regional decrease of myocardial perfusion in the affected segment. Chest pain always appeared later at 220 ± 19 sec after the appearance of disturbed myocardial perfusion. Regional myocardial perfusion returned to normal in all the patients after the atrial pacing was stopped. There was a spatial relationship between the region of the ventricles affected by disturbed perfusion and the region of the precordium showing abnormal electrocardiographic signs during the exercise test. In conclusion, this clinical study has shown that patients with chest pain who have coronary artery disease suffer decreases of regional myocardial perfusion in affected segments of the ventricles during episodes of angina pectoris induced by atrial pacing. Regional perfusion may increase, remain stable or decrease in the affected segment following the onset of a stress test such as atrial pacing. This probably represents the amount of reserve function and adaptation left in the diseased coronary circulation and may be a useful physiological indicator of the severity of coronary disease and of patients at high risk. ST segment depression and pain have a close temporal relationship to the decreases of regional myocardial perfusion that occur in these patients. These studies suggest that there is a close relationship between myocardial perfusion and metabolism in health and disease. Both myocardial perfusion and metabolism will have to be affected by any rational therapy for angina pectoris and ischemic heart disease
An evaluation of the Defensive Driving Course in New Zealand
The driving records of a sample of drivers ordered to complete - the Defensive Driving Course (New Zealand) by the Courts were compared with those of a sample of offending drivers, matched on age, sex
and prior driving record, who did not attend the course. Twelve
months before and after completion of the course, or for the comparison group, before and after the equivalent date, was the study period.
Attendance at the course appeared to make, at best, no difference to the accident rate, whereas the post-treatment conviction rate was comparatively lower following the course than following the standard treatment. This finding lends support to other research in the field which shows that driver education, while having no effect on accidents, does decrease the number of post-course convictions
Systematic techniques for assisting recruitment to trials (START): study protocol for embedded, randomized controlled trials
BACKGROUND: Randomized controlled trials play a central role in evidence-based practice, but recruitment of participants, and retention of them once in the trial, is challenging. Moreover, there is a dearth of evidence that research teams can use to inform the development of their recruitment and retention strategies. As with other healthcare initiatives, the fairest test of the effectiveness of a recruitment strategy is a trial comparing alternatives, which for recruitment would mean embedding a recruitment trial within an ongoing host trial. Systematic reviews indicate that such studies are rare. Embedded trials are largely delivered in an ad hoc way, with interventions almost always developed in isolation and tested in the context of a single host trial, limiting their ability to contribute to a body of evidence with regard to a single recruitment intervention and to researchers working in different contexts. METHODS/DESIGN: The Systematic Techniques for Assisting Recruitment to Trials (START) program is funded by the United Kingdom Medical Research Council (MRC) Methodology Research Programme to support the routine adoption of embedded trials to test standardized recruitment interventions across ongoing host trials. To achieve this aim, the program involves three interrelated work packages: (1) methodology - to develop guidelines for the design, analysis and reporting of embedded recruitment studies; (2) interventions - to develop effective and useful recruitment interventions; and (3) implementation - to recruit host trials and test interventions through embedded studies. DISCUSSION: Successful completion of the START program will provide a model for a platform for the wider trials community to use to evaluate recruitment interventions or, potentially, other types of intervention linked to trial conduct. It will also increase the evidence base for two types of recruitment intervention. TRIAL REGISTRATION: The START protocol covers the methodology for embedded trials. Each embedded trial is registered separately or as a substudy of the host trial
A meta-analysis of economic diplomacy and its effect on international economic flows
This meta-analysis deals with 29 empirical studies on the trade and investment impact of economic diplomacy (embassies, consulates and other diplomatic facilities, investment and export promotion offices, trade and state visits). The meta-regression results suggest that the significance of the coefficient of economic diplomacy is more pronounced when studies use embassies as an explanatory variable as compared to studies using consulates, trade missions, state visits and export promotion agencies. If the primary dependant variable under investigation is exports one may also expect to find more significant coefficients then in an otherwise similar regression explaining the relation between economic diplomacy and imports, total trade or foreign direct investment. Furthermore empirical design factors play a role in the reported results of the studies we reviewed. Studies based on a single country will in general show lower significance
De effectiviteit van economische diplomatie
Uit een meta-analyse van empirische studies naar de effecten van economische diplomatie blijkt dat deze een significante bijdrage levert aan de handels- en investeringsstromen. Economische diplomatie is een probaat middel tegen diverse vormen van internationaal marktfalen. Niet alle vormen van economische diplomatie sorteren echter eenzelfde effect
Imagining technology-enhanced learning with heritage artefacts: teacher-perceived potential of 2D and 3D heritage site visualisations
Background: There is much to be realised in the educational potential of national and world heritage sites. Such sites need to be supported in sharing their resources with a wide and international public, especially within formal education. Two-dimensional (2D) and three-dimensional (3D) heritage site visualisations could serve this need. Our study focuses on the teacher-perceived possibilities and benefits for education around such visualisations.
Purpose: We describe how a group of UK teachers perceive the potential of cross-curricular learning that could arise from an Italian world heritage site. The teachers commented on 2D visualisations of artefacts from this site, as well as the design of a 3D immersive environment to serve educational purposes. We consider as follows: (1) how the cross-curricular teaching potential of such resources is perceived, and (2) what design features of a 3D immersive environment teachers suggest are needed for educational explorations.
Sample: We recruited 10 teachers from the Midlands region of the UK and carried out semi-structured interviews.
Methods: Interviews were transcribed and a thematic analysis applied to the conversations. Questioning was grounded in the examination of 2D and 3D visual resources. This provoked cross-curricular and educational design thinking.
Results: Teacher responses highlighted a wide range of cross-curricular possibilities. However, they expressed a more ‘assimilative’ than ‘accommodative’ approach when relating resources to the curriculum. Such ‘assimilation’ involved seeing the site artefacts as raw material for more instrumental ‘curriculum activities’ (e.g. within art and design, geography, maths or literacy) rather than a more accommodative approach whereby curricular disciplines were exercised to make new meaning from the artefacts. In relation to 3D technology design, most teachers highlighted three technology features that would render it well matched to educational practice and three educational benefits over non-3D immersive environments.
Conclusions: Teachers can easily imagine a rich range of opportunities to utilise 2D and 3D heritage site artefacts within the curriculum. However, the largely assimilative nature of this cross-curricular appropriation suggests the value of providing more guidance and support to teachers in the interpretation and application of artefacts. Their design suggestions can usefully inform construction of educational features within 3D immersive technologies that support heritage site experiences
Dinoflagellate blooms and physical systems in the Gulf of Maine
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution May 1990Numerous studies have shown dinoflagellate blooms to be
closely related to density discontinuities and fronts in the ocean. The
spatial and temporal patterns of the dinoflagellate population
depend on the predominant mode of physical forcing, and its scales
of variability. The present study combined field sampling of
hydrographic and biological variables to examine the relationship of
dinoflagellate population distributions to physical factors along the
southwestern cost of the Gulf of Maine.
A bloom of Ceratium longipes occurred along this coast during
the month of June, 1987. A simple model which coupled along-isopycnal
diffusion with the logistic growth equation suggested that
the cells had a growth rate of about 0.1 d-1 , and had reached a
steady horizontal across-shelf distribution within about 10 d.
Fur~her variations in population density appeared to be related to
fluctuations of light with periods of -10 d. To our knowledge, this
was the first use of this simple diffusion model as a diagnostic tool
for quantifying parameters describing the growth and movement of
a specific phytoplankton population.
Blooms of the toxic dinoflagellate, Alexandrium tamarense
have been nearly annual features along the coasts of southern
Maine, New Hampshire and Massachusetts since 1972; however the
mechanisms controlling the distribution of cells and concomitant
shellfish toxicity are relatively poorly understood. Analysis of field
data gathered from April to September, 1987-1989, showed that in
two years when toxicity was detected in the southern part of this
region, A. tamarense cells were apparently transported into the
study area between Portsmouth and Cape Ann, Massachusetts, in a
coastally trapped buoyant plume. This plume appears to have been
formed off Maine by the outflow from the Androscoggin and Kennebec Rivers. Flow rates of these rivers, hydrographic sections,
and satellite images suggest that the plume had a duration of about
a month, and extended alongshore for several hundred kilometers.
The distribution of cells followed the position of the plume as it was
influenced by wind and topography. Thus when winds were
downwelling-favourable, cells were moved alongshore to the south,
and were held to the coast; when winds were upwelling-favourable,
the plume sometimes separated from the coast, advecting the cells
offshore.
The alongshore advection of toxic cells within a coastally
trapped buoyant plume can explain the temporal and spatial
patterns of shellfish toxicity along the coast. The general observation
of a north-to-south temporal trend of toxicity is consistent with the
southward advection of the plume. In 1987 when no plume was
present, Alexandrium tamarense cells were scarce, and no toxicity
was recorded at the southern stations. A hypothesis was formulated
explaining the development and spread of toxic dinoflagellate
blooms in this region. This plume-advection hypothesis included:
source A. tamarense populations in the north, possibly associated
with the Androscoggin and Kennebec estuaries; a relationship
between toxicity patterns and river flow volume and timing of flow
peaks; and a relationship between wind stresses and the distribution
of low salinity water and cells. Predictions of the plume-advection hypothesis were tested
with historical records of shellfish toxicity, wind speed and direction,
and river flow. The predictions tested included the north-south
progression of toxic outbreaks, the occurrence of a peak in river flow
prior to the PSP events, the relationship of transit time of PSP
toxicity along the coast with river flow volume, and the influence of
surface wind stress on the timing and location of shellfish toxicity.
All the predictions tested were supported by the historical records.
In addition it was found that the plume-advection hypothesis
explains many details of the timing and spread of shellfish toxicity,
including the sporadic nature of toxic outbreaks south of
Massachusetts Bay, and the apparently rare occurrence of toxicity
well offshore on Nantucket Shoals and Georges Bank.This research was supported by
ONR contract N00014-87-K-0007 and ONR grant N00014-89-J-111
to Donald M. Anderson, and NOAA Office of Sea Grant contract
NA86AA-D-SG090
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