The promises of educational technology: a reassessment

The claims made for educational technology have not always been realized. Many programmes in education based on media and technology have produced useful documentation and supportive research; others have failed. The current, comprehensive definition of educational technology is a helpful key to understanding how a problem-solving orientation is necessary to approach teaching/learning designs. The process of educational technology begins with an analysis of the problem, rather than with the medium as a solution. Examples of appropriate applications come from open universities and primary schools where distance, time, insufficient personnel, and inadequate facilities have led to a search for alternative means for teaching and learning. Less successful programmes tended to have confused goals and an emphasis on one medium. They also lacked: support services, staff training, quality software and a system focus. The threads which run through the more successful programmes are described. The lessons learned from fifty years of media and technology development in education and training are discussed with an eye toward the future. It is clear that educational technology as a problem-solving process will lead the field into the twenty-first century

Risk of death and cardiovascular outcomes with thiazolidinediones: a study with the general practice research database and secondary care data.

OBJECTIVE: To describe the likely extent of confounding in evaluating the risks of cardiovascular (CV) events and mortality in patients using diabetes medication. METHODS: The General Practice Research Database was used to identify inception cohorts of insulin and different oral antidiabetics. An analysis of bias and incidence of mortality, acute coronary syndrome, stroke and heart failure were analysed in GPRD, Hospital Episode Statistics and death certificates. RESULTS: 206,940 patients were identified. The bias analysis showed that past thiazolidinedione users had a lower mortality risk compared to past metformin users. There were no differences between past users of rosiglitazone and pioglitazone (adjusted RR of 1.04; 95% CI 0.93-1.18). Current rosiglitazone users had an increased risk of death (adjusted RR 1.20; 95% CI 1.08-1.34) and of hospitalisation for heart failure (adjusted RR of 1.73; 95% CI 1.19-2.51) compared to current pioglitazone users. Risk of mortality was increased two-fold shortly after starting rosiglitazone. Excess risk of death over 3 years with rosiglitazone was 0.3 per 100 in those aged 50-64 years, 2.0 aged 65-74, 3.0 aged 75-84, and 7.0 aged 85+. The cause of death with rosiglitazone was more likely to be due to a disease of the circulatory system. CONCLUSIONS: Higher risks for death (overall and due to cardiovascular disease) and heart failure were found for rosiglitazone compared to pioglitazone. These excess risks were largest in patients aged 65 years or older. The European regulatory decision to suspend rosiglitazone is supported by this study

Patterns of risk of cancer in patients with metal-on-metal hip replacements versus other bearing surface types: a record linkage study between a prospective joint registry and general practice electronic health records in England.

BACKGROUND: There are concerns that metal-on-metal hip implants may cause cancer. The objective of this study was to evaluate patterns and timing of risk of cancer in patients with metal-on-metal total hip replacements (THR). METHODS: In a linkage study between the English National Joint Registry (NJR) and the Clinical Practice Research Datalink (CPRD), we selected all THR surgeries (NJR) between 2003 and 2010 (n = 11,540). THR patients were stratified by type of bearing surface. Patients were followed up for cancer and Poisson regression was used to derive adjusted relative rates (RR). RESULTS: The risk of cancer was similar in patients with hip resurfacing (RR 0.69; 95% Confidence Interval [CI] 0.39–1.22) or other types of bearing surfaces (RR 0.96; 95% CI 0.64–1.43) compared to individuals with stemmed metal-on-metal THR. The pattern of cancer risk over time did not support a detrimental effect of metal hip implants. There was substantial confounding: patients with metal-on-metal THRs used fewer drugs and had less comorbidity. CONCLUSIONS: Metal-on-metal THRs were not associated with an increased risk of cancer. There were substantial baseline differences between the different hip implants, indicating possibility of confounding in the comparisons between different types of THR implants

Why didn't the Global Financial Crisis hit Latin America?

Latin America has a rich history of financial crises. However, it was relatively unharmed by the 2007-2009 Global Financial Crisis (GFC). This paper investigates why, and in particular the role of commodity prices and its institutional framework - in line with the fourth generation financial crisis model. We set up Early Warning Systems (EWS) for Argentina, Brazil and Mexico. These consist of an ordered logit model for currency crises for the period 1990-2007 with a dynamic factor model to deal with the large number of explanatory variables. We present forecasts for the period 2008-2009. We find that international indicators play an important role in explaining currency crises in Mexico, while banking indicators and commodities explain the currency crisis in Argentina and Brazil. Furthermore, debt and domestic economy indicators are relevant for Argentina and Mexico. Finally, we observe that currency crises in all three countries are related to institutional indicators. For none of the countries the Early Warning System would have issued an early warning for the GFC.Financial crises, Early Warning Systems, Latin America, dynamic factor models, ordered logit model,

Risk of Mortality (including Sudden Cardiac Death) and Major Cardiovascular Events in Users of Olanzapine and Other Antipsychotics: A Study with the General Practice Research Database.

Objective. Assess risk of cardiac events and mortality among users of olanzapine and other antipsychotics relative to nonusers. Methods. The General Practice Research Database was used to identify cohorts of antipsychotic users and nonusers with psychiatric illness. Outcomes included cardiac mortality, sudden cardiac death (SCD), all-cause mortality (excluding suicide), coronary heart disease (CHD), and ventricular arrhythmias (VA). Results. 183,392 antipsychotic users (including 20,954 olanzapine users) and 193,920 psychiatric nonusers were identified. There was a significantly higher rate of cardiac mortality (adjusted RR [aRR]: 1.53, CI, 1.12-2.09) in olanzapine users relative to psychiatric nonusers, consistent with findings for both atypical and typical antipsychotics. Relative to psychiatric nonusers, no increased risk of all-cause mortality was observed among olanzapine users (aRR: 1.04, CI, 0.93-1.17), but elevated all-cause mortality risk was observed when compared to all antipsychotic users (aRR: 1.75, CI, 1.64-1.87). There was no increased risk of CHD or VA among olanzapine users relative to psychiatric nonusers, consistent with findings for atypical but not typical antipsychotics. SCD cases were uncommon. Conclusions. Use of antipsychotic agents was associated with increased risk of all-cause and cardiac mortality. Patients treated with olanzapine were found to be at increased risk of cardiac mortality versus psychiatric nonusers

Interaction between hydrodynamics and seagrass canopy structure: Spatially explicit effects on ammonium uptake rates

The hypotheses that (1) different seagrass morphologies may facilitate different nutrient uptake rates under similar hydrodynamic forcing and (2) this effect on nutrient uptake rates is spatially explicit, with the highest uptake rates at edges of patches, where currents and turbulence are highest, were examined under unidirectional flow conditions.We thank Jos van Soelen, Bas Koutstaal, and Louie Haazen for invaluable technical assistance. In addition, we are grateful to Britta Gribsholt, Bart Veuger, Miguel Bernal, Juan Jose Vergara, and Alfredo Izquirdo for helpful discussion. In addition, we thank Josef D. Ackerman and the anonymous reviewers for comments that greatly improved the manuscript. This work and the first author were supported by an EU Marie Curie host fellowship for transfer of knowledge, MTKD-CT-2004-509254, and the Spanish national project EVAMARIA, CTM2005-00395/MAR. F.G.B. holds an EU Marie Curie individual fellowship, MEIF-CT-2005-515071. This is publication 4251 of the Netherlands Institute of Ecology (NIOO-KNAW)

Коректність задачі Коші для нескінченної системи нелінійних осциляторів, розміщених на двовимірній решітці

Стаття присвячена вивченню нескінченної системи диференціальних рівнянь, яка описує нескінченний ланцюг лінійно зв’язаних нелінійних осциляторів. Отримано результати про існування та єдиність локального та глобального розв’язків задачі Коші.The article deals with infinite systems of differential equations that describe infinite system of nonlinear oscillators on 2D–lattice. It is obtained results on existence and uniqueness of local and global solutions to the Cauchy problem

The Imperfective Past

The objective of our study was to investigate whether use of antipsychotics is associated with hip/femur fractures and whether pharmacological differences between antipsychotics are related to the occurrence of fractures.A case-control study was conducted, in which cases were defined as patients with a hip/femur fracture. Each patient was matched to one control patient. The association between use of antipsychotics and the occurrence of hip/femur fractures was evaluated using conditional logistic regression.The study included 44,500 patients from 683 general practices from different geographical areas in the UK, registered within the General Practice Research Database (GPRD). Exposure to antipsychotics was categorized as “no use”, “current use” and “prior use”.Both current and prior use of antipsychotics were associated with an approximately two-fold increased risk of fractures. After adjustment for possible confounders, a small significant effect remained (Odds Ratios (OR) of 1.3). We did not find an association between dose of antipsychotics, or between the degree of blockade of the alpha-1 adrenoceptor or histamine-1 receptor and risk of fractures. The total number of days of antipsychotic use was significantly associated with an increased risk of hip/femur fractures.We conclude that there is a small increased risk of hip/femur fractures associated with the use of antipsychotics. This risk increases with long-term use

Potential uptake of dissolved organic matter by seagrasses and macroalgae

Dissolved organic nitrogen (DON) acts as a large reservoir of fixed nitrogen. Whereas DON utilization is common in the microbial community, little is known about utilization by macrophytes. We investigated the ability of the coexisting temperate marine macrophytes Zostera noltii, Cymodocea nodosa, and Caulerpa prolifera to take up nitrogen and carbon from small organic substrates of different molecular complexities (urea, glycine, L-leucine, and L-phenylalanine) and from dissolved organic matter (DOM) derived from algal and bacterial cultures (substrates with a complex composition). In addition to inorganic nitrogen, nitrogen from small organic substrates could be taken up in significant amounts by all macrophytes. Substrate uptake by the aboveground tissue differed from that of the belowground tissue. No relationships between carbon and nitrogen uptake of small organics were found. The preference for individual organic substrates was related to their structural complexity and C:N ratio. Uptake of algae-derived organic nitrogen was of similar magnitude as inorganic nitrogen, and was preferred over bacteria-derived nitrogen. These results add to the growing evidence that direct or quick indirect DON utilization may be more widespread among aquatic macrophytes than traditionally thought.This research was supported by the regional government of Andalusia project FUNDIV (P07-RNM-2516), the Spanish Project CTM2008-00012/MAR, a European Reintegration Grant (MERG-CT-2007-205675), a travel grant from Schure-Beijerinck-Popping Fund (SBP/JK/2007-32) and the Netherlands Organization for Scientific Research. Thanks to Fidel Echevarrìa Navas (Director of CACYTMAR) for granting us access to facilities, and to Bas Koutstaal for helping with sample processing. We also thank the anonymous reviewers for their valuable comments which significantly improved this manuscript

Terahertz optically pumped silicon lasers

Stimulated terahertz (THz) emission from silicon single crystals doped by group-V donors has been obtained by optical excitation with pulsed infrared lasers. Pumping by a conventional TEA CO2 laser results in lasing on discrete lines between 1.3 and 7 THz (see figure). Laser thresholds can be as low as 10 kW/cm2. They depend on the donors species and the laser mechanism. Intracentre population inversion is realized between particular excited states which are large-spaced due to the chemical shift of the donor binding energy. The lifetime of an electron in an excited state (up to ~70 ps) is determined by the efficiency of phonon-assisted nonradiative relaxation. Optical excitation by the emission of a frequency-tunable free electron laser results in two different types of lasing. At relatively low pump intensities (~1 kW/cm2) the intracentre mechanism of lasing is dominating. At pump intensities above ~100 kW/cm2 stimulated scattering of pump photons on transverse acoustic intervalley phonons can occur in the vicinity of an impurity atom. This results in laser emission in the frequency range from 4.6 to 5.8 THz. In this case the laser frequency can be tuned proportionally to the pump frequency