Ideal Conditions (ideal + condition)

Distribution by Scientific Domains

Selected Abstracts

Fronto-striatal dysfunction and potential compensatory mechanisms in male adolescents with fragile X syndrome

Fumiko Hoeft
Abstract Response inhibition is an important facet of executive function. Fragile X syndrome (FraX), with a known genetic etiology (fragile X mental retardation-1 (FMR1) mutation) and deficits in response inhibition, may be an ideal condition for elucidating interactions among gene-brain-behavior relationships. Functional magnetic resonance imaging (fMRI) studies have shown evidence of aberrant neural activity when individuals with FraX perform executive function tasks, though the specific nature of this altered activity or possible compensatory processes has yet to be elucidated. To address this question, we examined brain activation patterns using fMRI during a go/nogo task in adolescent males with FraX and in controls. The critical comparison was made between FraX individuals and age, gender, and intelligent quotient (IQ)-matched developmentally delayed controls; in addition to a control group of age and gender-matched typically developing individuals. The FraX group showed reduced activation in the right ventrolateral prefrontal cortex (VLPFC) and right caudate head, and increased contralateral (left) VLPFC activation compared with both control groups. Individuals with FraX, but not controls, showed a significant positive correlation between task performance and activation in the left VLPFC. This potential compensatory activation was predicted by the interaction between FMR1 protein (FMRP) levels and right striatal dysfunction. These results suggest that right fronto-striatal dysfunction is likely an identifiable neuro-phenotypic feature of FraX and that activation of the left VLPFC during successful response inhibition may reflect compensatory processes. We further show that these putative compensatory processes can be predicted by a complex interaction between genetic risk and neural function. Hum Brain Mapp, 2007. © 2007 Wiley-Liss, Inc. [source]

Effects of carbaryl on green frog (Rana clamitans) tadpoles: Timing of exposure versus multiple exposures

Michelle D. Boone
Abstract The majority of studies on pesticide impacts have evaluated the effects of single exposures. However, multiple exposures to a pesticide may be more prevalent. The objective of our study was to determine how multiple exposures versus single exposure at different times during development affected survival to metamorphosis, tadpole survival, tadpole mass, and tadpole developmental stage of green frog (Rana clamitans) tadpoles reared at low and high density in outdoor cattle tank ponds. Tadpoles were exposed to carbaryl zero, one, two, or three times at 14-d intervals. We applied single doses of carbaryl at one of three times, specifically during early, mid, or late development. Overall, we found that multiple exposures had a greater impact than single exposures during development. More individuals reached metamorphosis in ponds exposed to multiple doses of carbaryl compared with controls, indicating that the presence of carbaryl stimulated metamorphosis. The presence of carbaryl in the aquatic environment also resulted in more developed tadpoles compared with controls. Tadpoles in control ponds did not reach metamorphosis and were less developed than individuals exposed to carbaryl; this effect indicates that, under ideal conditions, green frogs could overwinter in ponds so that greater size could be attained before metamorphosis in the following spring or summer. Our study demonstrated the importance of including realistic application procedures when evaluating the effects of a pesticide and that multiple exposures to a short-lived pesticide are more likely to affect an amphibian population. [source]

The potential for estradiol and ethinylestradiol degradation in english rivers

Monika D. Jürgens
Abstract Water samples were collected in spring, summer, and winter from English rivers in urban/industrial (River Aire and River Calder, Yorkshire, UK) and rural environments (River Thames, Oxfordshire, UK) to study the biodegradation potential of the key steroid estrogen 17,-estradiol (E2) and its synthetic derivate ethinylestradiol (EE2). Microorganisms in the river water samples were capable of transforming E2 to estrone (E1) with half-lives of 0.2 to 9 d when incubated at 20°C. The E1 was then further degraded at similar rates. The most rapid biodegradation rates were associated with the downstream summer samples of the River Aire and River Calder. E2 degradation rates were similar for spiking concentrations throughout the range of 20 ng/L to 500 ,g/L. Microbial cleavage of the steroid ring system was demonstrated by release of radiolabeled CO2 from the aromatic ring of E2 (position 4). When E2 was degraded, the loss of estrogenicity, measured by the yeast estrogen screen (YES) assay, closely followed the loss of the parent molecule. Thus, apart from the transient formation of E1, the degradation of E2 does not form other significantly estrogenic intermediates. The E2 could also be degraded when incubated with anaerobic bed sediments. Compared to E2, EE2 was much more resistant to biodegradation, but both E2 and EE2 were susceptible to photodegradation, with half-lives in the order of 10 d under ideal conditions. [source]

Typing of the immunological system in human embryos by coelocentesis

Maria Concetta Renda
Abstract Coelocentesis offers a new opportunity for gaining access to the human embryos from 28 d postfertilization. However, while some studies about its biochemical composition have been reported, our knowledge about immunological pattern of this compartment is still limited. For this reason, we studied the human coelomic fluids sampled from 6.6 to 10 wk of gestation. The majority of cellular population consisted in mesenchymal/epithelial cells. In fluids sampled before 10 wk we found only a preT Cell Receptor expression and an absence or a very low frequency of B lymphocytes, T lymphocytes and NK (natural killer) antigens. These preliminary data suggest that the immunological system in human embryos could be in the ideal conditions to start a process of tolerance induction. [source]

Perceptual error and the culture of open disclosure in Australian radiology

AG Pitman
Summary The work of diagnostic radiology consists of the complete detection of all abnormalities in an imaging examination and their accurate diagnosis. Errors in diagnostic radiology comprise perceptual errors, which are a failure of detection, and interpretation errors, which are errors of diagnosis. Perceptual errors are subject to rules of human perception and can be expected in a proportion of observations by any human observer including a trained professional under ideal conditions. Current legal standards of medical negligence make no allowance for perceptual errors, comparing human performance to an ideal standard. Diagnostic radiology in Australia has a culture of open disclosure, where full unbiased evidence from an examination is provided to the patient together with the report. This practice benefits the public by allowing genuine differences of opinion and also by allowing a second chance of correct diagnosis in cases of perceptual error. The culture of open disclosure, which is unique to diagnostic radiology, places radiologists at distinct medicolegal disadvantage compared with other specialties. (i) Perceptual error should be acknowledged as an integral inevitable part of diagnostic radiology; (ii) culture of open disclosure should be encouraged by the profession; and (iii) a pragmatic definition of medical negligence should reflect the imperfect performance of human observers. [source]

Thin-film intermediate band photovoltaics: advanced concepts for chalcopyrite solar cells

David Fuertes Marrón
Abstract We have studied the potential of thin-film photovoltaic devices provided with an intermediate band (IB). Cu-containing chalcopyrites appear as promising candidates, with maximum theoretical efficiencies above 45% under ideal conditions. This figure has been re-evaluated by considering a number of non-idealities, like optical and current losses and nonradiative recombination that affect current chalcopyrite-based devices. Strategies for the practical implementation of IBs in chalcopyrite hosts will be discussed, including the incorporation of foreign impurities in the chalcopyrite structure at substitutional sites of the cation sublattice and the realisation of nanostructured devices. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

The Use of a Population Balance Model in the Study of Inoculation of Soybean Seeds in a Spouted Bed

Claudio R. Duarte
Abstract The coating of soybean seeds with bacteria and micronutrients favours the vigorous growth of the plant, dispensing with the use of ammoniacal fertilizers. The optimum thickness of the coating should allow the fundamental gaseous interchanges for the germination and the ideal conditions for the activity of the bacteria. The objective of this work was to simulate dynamic mass distribution of soybean seeds covered with bacteria and macronutrients in spouted bed through a specific program developed in Maple V®. The validation of the model is done through 16 experiments carried out in a spouted bed with spray at the top. L'enduction de graines de soja par des bactéries et des micronutriments favorise une croissance vigoureuse des plantes, ce qui dispense de recourir à des fertilisants ammoniaqués. Une épaisseur optimale de l'enduit devrait permettre les échanges gazeux de base nécessaires à la germination et correspondre aux conditions idéales pour l'activité des bactéries. L'objectif de ce travail est de simuler la distribution en masse dynamique des graines de soja recouvertes de bactéries et micronutriments dans un lit jaillissant par un logiciel spécifique mis au point dans Maple V®. La validation du modèle est réalisée par seize expériences menées en lit fluidisé avec atomisation par le sommet. [source]

Recruitment dynamics of invasive species in rainforest habitats following Cyclone Larry

Abstract In tropical forests, natural disturbance creates opportunities for species to claim previously utilized space and resources and is considered an important mechanism in the maintenance of species diversity. However, ecologists have long recognized that disturbance also promotes exotic plant invasions. Cyclones cause extensive defoliation, loss of major branches and multiple tree falls, resulting in a significantly more open canopy and increased light and heat levels in the understorey. The widespread and massive disturbance caused by cyclones provides ideal conditions for rapid recruitment and spread of invasive species. The ecological roles of invasive species in rainforest habitats following such a severe disturbance are poorly understood. Severe category 4 Cyclone Larry crossed the North Queensland coast in March 2006 causing massive disturbance to rainforest habitats from Tully to Cairns and west to the Atherton Tablelands. We established 10 plots in an area extensively damaged by this cyclone near El Arish in North Queensland. On each plot nine 2 × 2 m quadrats were established with three quadrats per plot in each of the following treatments: (i) complete debris removal down to the soil layer, (ii) removal of coarse woody debris only, and (iii) uncleared. We monitored recruitment, growth and mortality of all native and invasive species in the 90 quadrats every 3 months since the cyclone. Here we present the recruitment dynamics of invasive species across the study area in relation to the level of disturbance, the type of quadrat treatment, and the diversity and abundance of the native recruiting flora over the first 12 months post-cyclone. Our results suggest that invasive species will mostly comprise a transient component of the flora in the early stages of the successional response. However, some species may have longer-term effects on the successional trajectory of the rainforest and future forest composition and structure. [source]