326 research outputs found
Relaxation and derelaxation of pure and hydrogenated amorphous silicon during thermal annealing experiments
The structural relaxation of pure amorphous silicon (a-Si) and hydrogenated
amorphous silicon (a-Si:H) materials, that occurs during thermal annealing
experiments, has been analysed by Raman spectroscopy and differential scanning
calorimetry. Unlike a-Si, the heat evolved from a-Si:H cannot be explained by
relaxation of the Si-Si network strain, but it reveals a derelaxation of the
bond angle strain. Since the state of relaxation after annealing is very
similar for pure and hydrogenated materials, our results give strong
experimental support to the predicted configurational gap between a-Si and
crystalline silicon.Comment: 15 pages, 3 figures, 1 table to be published in Applied Physics
Letter
Bacterial Respiration of Arsenate and Its Significance in the Environment
Although arsenic is a trace element in terms of its natural abundance, it nonetheless
has a common presence within the earth's crust. Because it is classified as a
group VB element in the periodic table, it shares many chemical and biochemical
properties in common with its neighbors phosphorus and nitrogen. Indeed, in the
case of this element's most oxidized (+5) oxidation state, arsenate [HAsO_4^(2-) or
As (V)], its toxicity is based on its action as an analog of phosphate. Hence,
arsenate ions uncouple the oxidative phosphorylation normally associated with
the enzyme glyceraldehyde 3-phosphate dehydrogenase, thereby preventing the
formation ofphosphoglyceroyl phosphate, a key high-energy intermediate in glycolysis.
To guard against this, a number of bacteria possess a detoxifying arsenate
reductase pathway (the arsC system) whereby cytoplasmic enzymes remove internal
pools of arsenate by achieving its reduction to arsenite [H_2AsO_3- or As
(III)]. However, because the arsenite product binds with internal sulfhydryl
groups that render it even more toxic than the original arsenate, efficient arsenite
efflux from the cell is also required and is achieved by an active ion ''pumping'' system (1). The details of this bacterial arsenic detoxification phenomenon have
been well established in the literature, and Chapter 10 in this volume provided
a thorough review. Here, we discuss bacterial respiration of arsenate and its significance
in the environment. As a biological phenomenon, respiratory growth
on arsenate is quite remarkable, given the toxicity of the element. Moreover, the
consequences of microbial arsenate respiration may, at times, have a significant
impact on environmental chemistry
The configurational energy gap between amorphous and crystalline silicon
The crystallization enthalpy of pure amorphous silicon (a-Si) and hydrogenated a-Si was measured by differential scanning calorimetry (DSC) for a large set of materials deposited from the vapour phase by different techniques. Although the values cover a wide range (200-480 J/g), the minimum value is common to all the deposition techniques used and close to the predicted minimum strain energy of relaxed a-Si (240 ± 25 J/g). This result gives a reliable value for the configurational energy gap between a-Si and crystalline silicon. An excess of enthalpy above this minimum value can be ascribed to coordination defects
Analyzing false memories in children with associative lists specific for their age
Two experiments attempted to resolve previous contradictory findings concerning developmental trends in false memories within the Deese-Roediger-McDermott (DRM) paradigm by using an improved methodology-constructing age-appropriate associative lists. The research also extended the DRM paradigm to preschoolers. Experiment 1 (N = 320) included children in three age groups (preschoolers of 3-4 years, second-graders of 7-8 years, and preadolescents of 11-12 years) and adults, and Experiment 2 (N = 64) examined preschoolers and preadolescents. Age-appropriate lists increased false recall. Although preschoolers had fewer false memories than the other age groups, they showed considerable levels of false recall when tested with age-appropriate materials. Results were discussed in terms of fuzzy-trace, source-monitoring, and activation frameworks
Can the crystallization rate be independent from the crystallization enthalpy? The case of amorphous silicon
The crystallization enthalpy measured in a large series of amorphous silicon (a-Si) materials
varies within a factor of 2 from sample to sample (Kail et al 2011 Phys. Status Solidi RRL 5
361). According to the classical theory of nucleation, this variation should produce large
differences in the crystallization kinetics leading to crystallization temperatures and activation
energies exceeding 550 C and 1.7 eV, respectively, the âstandardâ values measured for a-Si
obtained by self-implantation. In contrast, the observed crystallization kinetics is very similar
for all the samples studied and has no correlation with the crystallization enthalpy. This
discrepancy has led us to propose that crystallization in a-Si begins in microscopic domains
that are almost identical in all samples, independently of their crystallization enthalpy.
Probably the existence of microscopic inhomogeneities also plays a crucial role in the
crystallization kinetics of other amorphous materials and glasses
Development of intuitive rules: Evaluating the application of the dual-system framework to understanding children's intuitive reasoning
This is an author-created version of this article. The original source of publication is Psychon Bull Rev. 2006 Dec;13(6):935-53
The final publication is available at www.springerlink.com
Published version: http://dx.doi.org/10.3758/BF0321390
Female-Oriented Male-Male Erotica: Comparison of the Engaged Anglophone Demographic and That of the Greater China Area
Our aim is to compare comprehensive data on the engaged demographics of female-oriented male-male erotica in Anglophone regions and that of the greater China area. Our study constitutes the largest such data set in each region (Anglophone N = 1707; Chinese N = 1498). Data were analysed from our online Boysâ Love (BL) fandom survey: one version in English and an almost identical version in Chinese. We confirm that the engaged Anglophone demographic includes more men, people with a wider range of sexual orientations, lower proportion of heterosexual identification, and a wider and older age range. We provide greater detail than ever before and demonstrate engagement with BL by young straight men and questioning of sexual identity by female fans, at least in the Anglophone West. Finally, we provide novel evidence that a broad demographic of young people in the greater China area is familiar with BL as a casual interest in contrast to Anglophone regions where it is more of an intense and niche pass-time. We offer important insights into a global erotic entertainment by-and-for women which is influencing the mainstream but under increasing legislative scrutiny
Treatment of rising damp in historical buildings: wall base ventilation
Intervention in older buildings increasingly requires extensive and objective knowledge of what one will be working with. The multifaceted aspect of work carried out on buildings tends to encompass a growing number of specialities, with marked emphasis on learning the causes of many of the problems that affect these buildings and the possible treatments that can solve them. Moisture transfer in walls of old buildings, which are in direct contact with the ground, leads to a migration of soluble salts responsible for many building pathologies.http://www.sciencedirect.com/science/article/B6V23-4H7T0H7-1/1/f5e8a4ec173c5dadf120770678facf4
Crossâcultural assessment of HIVâassociated cognitive impairment using the Kaufman assessment battery for children: a systematic review
Introduction: Despite improved efficacy of, and access to, combination antiretroviral therapy (cART), HIVâassociated cognitive impairments remain prevalent in both children and adults. Neuropsychological tests that detect such impairment can help clinicians formulate effective treatment plans. The Kaufman Assessment Battery for Children (KABC), although developed and standardized in the United States, is used frequently in many different countries and cultural contexts to assess paediatric performance across various cognitive domains. This systematic review investigated the crossâcultural utility of the original KABC, and its 2nd edition (KABCâII), in detecting HIVâassociated cognitive impairment in children and adolescents.Methods: We entered relevant keywords and MeSH terms into the PubMed, PsycInfo, EBSCOHost, ProQuest, and Scopus databases, with search limits set from 1983â2017. Two independent reviewers evaluated the retrieved abstracts and manuscripts. Studies eligible for inclusion in the review were those that (a) used the KABC/KABCâII to assess cognitive function in children/adolescents aged 2â18Â years, (b) featured a definition of cognitive impairment (e.g. >2 SD below the mean) or compared the performance of HIVâinfected and uninfected control groups, and (c) used a sample excluded from population on which the instruments were normed.Results and discussion: We identified nine studies (eight conducted in African countries, and one in the United Kingdom) to comprise the reviewâs sample. All studies detected cognitive impairment in HIVâinfected children, including those who were cARTânaĂŻve or who were cART treated and clinically stable. KABC/KABCâII subtests assessing simultaneous processing appeared most sensitive. Evaluation of the methodological quality of the selected studies by two independent reviews suggested that shortcomings included reporting and selection biases.Conclusions: This systematic review provides evidence for the crossâcultural utility of the KABC/KABCâII, particularly the simultaneous processing subtests, in detecting cognitive impairment in HIVâinfected children (including those who are clinically stable). Although the current results suggest there is justification for using the KABC/KABCâII primarily in East Africa, further investigation is required to explore the instrumentâs utility in other HIVâprevalent regions of the globe.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138351/1/jia21412.pd
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