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1.
Nature ; 464(7287): 384-7, 2010 Mar 18.
Artículo en Inglés | MEDLINE | ID: mdl-20237564

RESUMEN

Of the over 400 known exoplanets, there are about 70 planets that transit their central star, a situation that permits the derivation of their basic parameters and facilitates investigations of their atmospheres. Some short-period planets, including the first terrestrial exoplanet (CoRoT-7b), have been discovered using a space mission designed to find smaller and more distant planets than can be seen from the ground. Here we report transit observations of CoRoT-9b, which orbits with a period of 95.274 days on a low eccentricity of 0.11 +/- 0.04 around a solar-like star. Its periastron distance of 0.36 astronomical units is by far the largest of all transiting planets, yielding a 'temperate' photospheric temperature estimated to be between 250 and 430 K. Unlike previously known transiting planets, the present size of CoRoT-9b should not have been affected by tidal heat dissipation processes. Indeed, the planet is found to be well described by standard evolution models with an inferred interior composition consistent with that of Jupiter and Saturn.

2.
Rev Sci Instrum ; 92(3): 033103, 2021 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-33820098

RESUMEN

In the frequency-domain multiplexing (FDM) scheme, transition-edge sensors (TESs) are individually coupled to superconducting LC filters and AC biased at MHz frequencies through a common readout line. To make efficient use of the available readout bandwidth and to minimize the effect of non-linearities, the LC resonators are usually designed to be on a regular grid. The lithographic processes, however, pose a limit on the accuracy of the effective filter resonance frequencies. Off-resonance bias carriers could be used to suppress the impact of intermodulation distortions, which, nonetheless, would significantly affect the effective bias circuit and the detector spectral performance. In this paper, we present a frequency shift algorithm (FSA) to allow off-resonance readout of TESs, while preserving the on-resonance bias circuit and spectral performance, demonstrating its application to the FDM readout of an x-ray TES microcalorimeter array. We discuss the benefits in terms of mitigation of the impact of intermodulation distortions at the cost of increased bias voltage and the scalability of the algorithm to multi-pixel FDM readout. We show that with FSA, in the multi-pixel and frequencies shifted on-grid, the line noises due to intermodulation distortion are placed away from the sensitive region in the TES response and the x-ray performance is consistent with the single-pixel, on-resonance level.

3.
Trends Biotechnol ; 25(1): 16-23, 2007 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-17113174

RESUMEN

The combination of web technology, knowledge of bioprocess engineering, and theories on learning and instruction might yield innovative learning material for bioprocess engineering. In this article, an overview of the characteristics of web-based learning material is given, as well as guidelines for the design of learning material from theories of learning and instruction and from the bioprocess engineering domain. A diverse body of learning material is presented, which illustrates the application of these guidelines; this material has been developed during the past six years for different courses, mostly at undergraduate level, and it illustrates how web-based learning material can enable various different approaches to learning objectives that might improve overall learning. Such learning material has been used for several years in education, it has been evaluated with positive results, and is now part of the regular learning material for bioprocess engineering at Wageningen University.


Asunto(s)
Ingeniería Biomédica/educación , Redes de Comunicación de Computadores , Educación a Distancia/métodos , Educación a Distancia/normas
4.
Int J Epidemiol ; 23(2): 386-92, 1994 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-8082967

RESUMEN

Neonatal tetanus (NNT) is a leading cause of neonatal mortality in developing countries and is frequently called 'the silent epidemic'. It is endemic in over 90 countries throughout the world. Incidence is often not known, obstructing cost-effective resource management for control measures. In many developing countries NNT is responsible for one-half of the neonatal mortality and up to one-quarter of infant mortality. Case-fatality rates (CFR) can, even with treatment, reach 80-90%. Operational tools for the rapid identification of NNT risk areas need to be developed for WHO's programme which calls for the elimination of NNT by 1995. Results of a rapid assessment technique, carried out in 1990, were compared with those found in a household survey, which was independently carried out in Jalisco, Mexico, in 1988. One approach used random sample survey techniques in rural communities, which in previous years had reported NNT. Of 40 neonatal deaths, 8 (20%) were attributable to NNT. The annual incidence rate was 4.6/1000 livebirths. Using this as the 'gold standard', a rapid assessment technique was evaluated. The NNT cases seen at health services were randomly matched with other neonatal illnesses obtained from health records and then mapped. Age-specific catchment areas for hospitals under investigation and risk areas for NNT were obtained. Areas without NNT cases but with other neonatal illnesses have been operationally considered to be at low risk for NNT. The use of health services by neonates with other pathologies supports the hypothesis that an NNT case, if it occurred within the same time period and area under investigation, would most probably have been admitted.(ABSTRACT TRUNCATED AT 250 WORDS)


Asunto(s)
Países en Desarrollo , Tétanos/prevención & control , Antisepsia , Causas de Muerte , Control de Enfermedades Transmisibles/tendencias , Estudios Transversales , Femenino , Encuestas Epidemiológicas , Humanos , Incidencia , Lactante , Recién Nacido , Masculino , México/epidemiología , Partería , Embarazo , Factores de Riesgo , Tétanos/mortalidad , Tétanos/transmisión
5.
J Am Geriatr Soc ; 41(1): 53-6, 1993 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-8418124

RESUMEN

OBJECTIVE: To compare hand-held isometric muscle strength measurement to an isokinetic muscle strength measurement in a healthy elderly population. DESIGN: Cross-sectional survey. SETTING: Retirement community in Southeastern Arizona. PARTICIPANTS: Thirty-two volunteers (16 men and 16 women) age 60 and over (mean age 70.3 years) who were free of musculoskeletal problems and did not have significant health problems. INTERVENTIONS: None. MEASUREMENTS: Isometric muscle strength was determined using a hand-held isometric strength device (Penny and Giles) for elbow flexion and extension and knee flexion and extension. Isokinetic muscle strength (average peak torque and average work per repetition) was measured on the same individuals using a Lido isokinetic dynamometer. RESULTS: Correlations between the strength measurement techniques were generally favorable with the lowest correlation being .72, (95 percent confidence interval .50-.86) and the highest being .85, (95 percent confidence interval .72-.93). However, there was substantial variability of hand-held strength reading at some levels of isokinetic strength. CONCLUSIONS: Hand-held dynamometry for strength measurement correlates strongly with measurement of strength using isokinetic dynamometry. Despite these high correlations, there is remaining variability of hand-held muscle strength readings when compared with isokinetic strength measurement at some levels of isokinetic muscle strength. Modification of the testing methodology or instrumentation used in this study is needed to improve the consistency of these measurements.


Asunto(s)
Evaluación Geriátrica , Contracción Isométrica/fisiología , Contracción Isotónica/fisiología , Anciano , Arizona , Estudios Transversales , Codo/fisiología , Diseño de Equipo/normas , Femenino , Humanos , Rodilla/fisiología , Masculino , Persona de Mediana Edad , Reproducibilidad de los Resultados
6.
Soc Sci Med ; 37(7): 897-904, 1993 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-8211308

RESUMEN

This study estimates the proportion of essential drugs out of all drugs offered for sale in six regions of the developing world by the 20 largest European pharmaceutical companies. The total number of drugs offered for sale by the 20 companies is estimated from citations in the most important drug compendia in each region for 1988 and 1989. Essential drugs are defined as drugs listed on the 1988 version of the World Health Organization's (WHO) essential drugs list or equivalent to WHO essential drugs. Only 482, or 16% of a total of 3021 cited drugs were essential drugs or equivalent to an essential drug. The proportion for each company ranged from a low of 5.4% to a maximum of 39.0%. A high proportion, 41.7%, of the 2539 non-essential drugs cited in the compendia contained two or more active ingredients, compared to only 9.5% of the essential drugs. The results indicate that European pharmaceutical companies have yet to focus their drug marketing efforts in developing countries on the essential drugs recommended by the WHO. The ethical responsibility of the pharmaceutical companies is discussed, particularly in respect to their sales on the private market.


Asunto(s)
Países en Desarrollo , Industria Farmacéutica , Preparaciones Farmacéuticas , África , Brasil , Ética Profesional , Europa (Continente) , India , México , Medio Oriente
7.
J Low Temp Phys ; 167(3-4): 214-219, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-26069348

RESUMEN

At SRON we are studying the performance of a Goddard Space Flight Center single pixel TES microcalorimeter operated in an AC bias configuration. For x-ray photons at 6 keV the pixel shows an x-ray energy resolution ΔEFWHM =3.7 eV, which is about a factor 2 worse than the energy resolution observed in an identical DC-biased pixel. In order to better understand the reasons for this discrepancy we characterised the detector as a function of temperature, bias working point and applied perpendicular magnetic field. A strong periodic dependency of the detector noise on the TES AC bias voltage is measured. We discuss the results in the framework of the recently observed weak-link behaviour of a TES microcalorimeter.

11.
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