The time-resolved luminescence characteristics of Ce and Ce/Pr doped YAG ceramics obtained by high pressure technique

Transparent Ce and Ce/Pr doped YAG ceramics were prepared under high pressures (up to 8 GPa) and relative low temperature (450 °C). Grain size of the ceramics is less than 50 nm. However unknown defects or disorders strains on grain boundaries caused the additional absorption in these ceramics. The luminescence intensity, spectra and the decay time dependence on pressure applied during ceramic preparation were studied. Concentration of some intrinsic point defect was reduced under the high pressure applied for sintering process.It is shown that formation time of the excited state of Ce luminescence depends on the pressure applied during ceramic sintering.     

Excitonic luminescence in ZnO nanopowders and ceramics

Fast photoluminescence spectra in the spectral region of 3.1–3.45 eV in ZnO and ZnO:Al ceramics were studied at 14 and 300 K. Ceramics with grains smaller than 100 nm were sintered from nanopowders by high pressure (8 GPa) and low temperature (350 °C). Ceramics with grain sizes 1–5 μm were sintered at 1400 °C. It is shown that excitonic luminescence spectra depend on the ceramics grain size, post preparing annealing and doping. The excitonic luminescence decay time was faster than 2 ns and the afterglow at 30 ns was 0.05%.     

Localisation of a gene for non-specific X linked mental retardation (MRX46) to Xq25-q26

Feeding difficulty and malnutrition are common in disabled children. Intake may be reduced because of anorexia, chewing and swallowing difficulties, or vomiting. Feeding is often time consuming, unpleasant, and may result in aspiration. Malnutrition may result in impaired growth and neurodevelopment, and impaired cardiorespiratory, gastrointestinal, and immune functions. Multidisciplinary assessment is recommended and should include a feeding history, oral-motor examination, and nutritional assessment. The energy requirements of most disabled children are less than those for a normal child of the same age but may be increased by spasticity, athetosis, convulsions, and recurrent infections. Micronutrient deficiencies may occur even in children receiving nutritionally complete feeds if the volume is reduced because of low energy requirements. Oral intake may be improved by a change of posture, special seating, feeding equipment, oral desensitization, mashing or pureeing of lumpy food, thickening of liquids, use of calorie supplements, and treatment of reflux/esophagitis. Non-oral feeding should be considered when oral feeding is unsafe, not enjoyable, inadequate, or very time consuming. Long-term support requires a gastrostomy. This is less obtrusive than a nasogastric tube, less likely to become displaced, less traumatic, and is associated with improved quality of life, but is also associated with significant morbidity. If there is symptomatic reflux a fundoplication may be required, but this is associated with significant mortality and substantial morbidity.     

Cardioprotective effects of the novel adenosine A1/A2 receptor agonist AMP 579 in a porcine model of myocardial infarction

This study examined the cardioprotective effects and pharmacology of the novel adenosine A1/A2 receptor agonist ([1S-[1a,2b,3b, 4a(S*)]]-4-[7-[[2-(3-chloro-2-thienyl)-1-methylpropyl]amino]-3H-imida zo[4,5-b] pyridyl-3-yl] cyclopentane carboxamide) (AMP 579), in a model of myocardial infarction. Experiments were performed in pentobarbital-anesthetized pigs in which myocardial infarction was induced by a 40-min occlusion of the left anterior descending coronary artery, followed by 3 hr of reperfusion. This procedure resulted in approximately 20% of the left ventricle being made ischemic in all test groups. In untreated animals, an infarct size equal to 56 +/- 5% of the ischemic area was observed. Preconditioning, with two cycles of 5 min of ischemia followed by 10-min reperfusion, resulted in a 70% reduction in infarct size (17 +/- 5%) relative to risk area. Administration of AMP 579 30 min before ischemia (3 microg/kg i.v. followed by 0.3 microg/kg/min i.v. through 1 hr of reperfusion) did not change blood pressure, HR or coronary blood flow but resulted in marked cardioprotection: a 98% reduction in infarct size (1 +/- 1%) relative to risk area. Moreover, whereas approximately 90% of control pigs suffered ventricular fibrillation during ischemia, no fibrillation was observed in animals treated with AMP 579. Further experiments determined the effects of AMP 579 when administered 30 min after the onset of myocardial ischemia, 10 min before reperfusion. Two doses were studied: a low hemodynamically silent dose (3 microg/kg + 0.3 microg/kg/min through 1 hr of reperfusion) and a 10-fold higher dose that did cause reductions in blood pressure and HR. Both doses of AMP 579 produced a comparable cardioprotective effect, reducing infarct size to approximately 50% of that observed in control animals. The cardioprotective effect of AMP 579 was a consequence of adenosine receptor stimulation, because it was completely inhibited by pretreatment with the specific adenosine receptor antagonist CGS 15943 (1 mg/kg i.v.). However, the selective A1 receptor agonist GR 79236 (3 microg/kg + 0.3 microg/kg/min i.v.) did not reduce infarct size, which suggests that under these experimental conditions, stimulation of adenosine A2 receptors is important for the cardioprotective effect of AMP 579. The adenosine-regulating agent acadesine (5 mg/kg + 0.5 mg/kg/min i.v.) also failed to reduce infarct size. In conclusion, the novel adenosine A1/A2 receptor agonist AMP 579 produces marked cardioprotection whether administered before myocardial ischemia or reperfusion. Cardioprotection is not dependent on changes in afterload or myocardial oxygen demand and is a consequence of adenosine receptor stimulation. The pharmacological profile of AMP 579 in this model is consistent with its potential utility in the treatment of acute myocardial infarction.     

Is fecundability associated with month of birth? An analysis of 19th and early 20th century family reconstitution data from The Netherlands

The relationship between fecundability and month of birth was investigated in a cohort of 1526 women who married between 1802 and 1929, using only women whose first marriage occurred before the age of 35 years. On the basis of their time to pregnancy (TTP, calculated as time between wedding and first birth minus gestational length), women were categorized into two groups: fecunds (TTP up to 12 months or prenuptial conceptions, n = 1348) and subfecunds (TTP >18 months, n = 118). By use of logistic regression, cosinor functions with a period of 1 year or 6 months and variable shift and amplitude were fitted through the monthly odds of subfecunds versus fecunds. The best fitting curve was unimodal, with a zenith in September (P = 0.13 for H0: no differences). Exclusion of childless women (n = 36, minimum follow-up 5 years) from the subfecunds led to a similar curve (P < 0.01), while childless women, as compared with fecunds, showed a birth distribution that was best represented with a bimodal curve with zeniths in January and July (P = 0.06). This study provides evidence for the existence of differences in fecundability by month of birth. The cause of this relationship is unclear, but may lie in a melatonin-dependent circannual variability of the quality of the oocyte.     

Taming monsters: The cultural domestication of new technology

Central to public discomfort about new technologies is the notion that they are unnatural. Experts often suppose that better knowledge of technology and risks would help overcome public aversion. This assumption turns out to be fairly fruitless, often even increasing social polarization. The pattern of diverging risk assessments about technology might be improved by a better understanding of the moral gut feelings at stake. However, current technology ethics does not seem to be equipped for elaborating theories to explain public discomfort. Either public fear is not taken seriously, or ethical–theoretical rationalizations of moral intuitions lead to unsatisfactory, naturalist constructions, such as the intrinsic value of nature.For a better understanding of current risk controversies, a detour is made to the cultural anthropology of Mary Douglas on pre-modern ideas regarding danger. This offers some clarifying insights into modern perceptions of technological risks. Departing from anthropological observations, a so-called monster theory is sketched, which gives an explanation for the fascination with and aversion towards new technology, leaving aside ‘naturalist’ and ‘nature-skeptic’ explanations of technology ethics. Monster theory offers a point of departure for a new, pragmatic approach to controversies about new technology, the approach being named a pragmatist monster-ethics. It tells us we have to reflect on and shift cultural categories as well as to adapt technologies in order to domesticate our technological ‘monsters’.     

Supervised and unsupervised learning of multidimensional acoustic categories.

Learning to recognize the contrasts of a language-specific phonemic repertoire can be viewed as forming categories in a multidimensional psychophysical space. Research on the learning of distributionally defined visual categories has shown that categories defined over 1 dimension are easy to learn and that learning multidimensional categories is more difficult but tractable under specific task conditions. In 2 experiments, adult participants learned either a unidimensional or a multidimensional category distinction with or without supervision (feedback) during learning. The unidimensional distinctions were readily learned and supervision proved beneficial, especially in maintaining category learning beyond the learning phase. Learning the multidimensional category distinction proved to be much more difficult and supervision was not nearly as beneficial as with unidimensionally defined categories. Maintaining a learned multidimensional category distinction was only possible when the distributional information that identified the categories remained present throughout the testing phase. We conclude that listeners are sensitive to both trial-by-trial feedback and the distributional information in the stimuli. Even given limited exposure, listeners learned to use 2 relevant dimensions, albeit with considerable difficulty. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Control and regulation of metabolic fluxes in microbes by substrates and enzymes

The control of enzymes and substrates on the flux through microbial metabolic pathways can be quantified in terms of flux control coefficients. In pathways involving group transfer, the summation theorem for flux control by the enzymes has to be modified: the sum of control by all enzymes is between 1 and 2. The phosphoenolpyruvate:glucose phosphotransferase system is such a pathway. Experimental determination of the control by the enzymes in this pathway is under way. The control of the enzymes on the glycolytic flux in yeast is low, with the possible exception of the uptake step. In Klebsiella pneumoniae potassium and ammonium ions can simultaneously be 'limiting', (i.e. have significant control on growth) at pH6, but not at pH8. This may be due to the fact that at pH8 the high-affinity potassium uptake system is absent.     

The cardiovascular interaction between caffeine and nicotine in humans

In a placebo-controlled, double-blind randomized design, we investigated the cardiovascular interaction between caffeine (250 mg intravenously) and nicotine (4 mg chewing gum) in 10 healthy volunteers, both under baseline conditions and during physical and mental stress (standing up and mental arithmetic). Caffeine alone induced a significant increase in blood pressure associated with a decrease in heart rate, whereas nicotine alone increased both blood pressure and heart rate. The combination of caffeine and nicotine increased systolic and diastolic blood pressure by 10.8 +/- 2.0 and 12.4 +/- 1.9 mm Hg, respectively. This pressor response did not differ significantly from the calculated additive effects of caffeine and nicotine on blood pressure, measuring 12.9 +/- 2.0 and 14.2 +/- 2.1 mm Hg, respectively. Heart rate and forearm blood flow also showed a similar response when the combination of caffeine and nicotine was compared with the calculated sum. During physical stress (standing up), blood pressure, heart rate, and plasma catecholamines increased in the placebo test. The pressor response to standing up was less pronounced after the combination of caffeine and nicotine compared with the sum of the separate effects (combination versus sum: delta diastolic blood pressure, 24.7 +/- 1.9 versus 35.2 +/- 2.6 mm Hg [p < 0.01]; delta mean arterial pressure, 22.1 +/- 2.0 mm Hg versus 28.6 +/- 1.6 mm Hg [p < 0.05]). The plasma catecholamine response did not differ between the combination and the sum of both drugs. During mental arithmetic, blood pressure, heart rate, and forearm blood flow increased in the placebo test. The forearm vasodilator response to mental stress was attenuated by the combination of caffeine and nicotine compared with the sum of both drugs (combination versus sum: delta forearm blood flow, -0.1 +/- 0.3 versus 1.4 +/- 0.5 ml/100 ml/min [p < 0.05]). We conclude that the combined administration of caffeine and nicotine shows additive effects on cardiovascular parameters during baseline conditions but less than additive effects during sympathoadrenal stimulation.