On the segmentation and classification of hand radiographs

This research is part of a wider project to build predictive models of bone age using hand radiograph images. We examine ways of finding the outline of a hand from an X-ray as the first stage in segmenting the image into constituent bones. We assess a variety of algorithms including contouring, which has not previously been used in this context. We introduce a novel ensemble algorithm for combining outlines using two voting schemes, a likelihood ratio test and dynamic time warping (DTW). Our goal is to minimize the human intervention required, hence we investigate alternative ways of training a classifier to determine whether an outline is in fact correct or not. We evaluate outlining and classification on a set of 1370 images. We conclude that ensembling with DTW improves performance of all outlining algorithms, that the contouring algorithm used with the DTW ensemble performs the best of those assessed, and that the most effective classifier of hand outlines assessed is a random forest applied to outlines transformed into principal components

Structure of the silicon vacancy in 6H-SiC after annealing identified as the carbon vacancy–carbon antisite pair

We investigated radiation-induced defects in neutron-irradiated and subsequently annealed 6H-silicon carbide (SiC) with electron paramagnetic resonance (EPR), the magnetic circular dichroism of the absorption (MCDA), and MCDA-detected EPR (MCDA-EPR). In samples annealed beyond the annealing temperature of the isolated silicon vacancy we observed photoinduced EPR spectra of spin S=1 centers that occur in orientations expected for nearest neighbor pair defects. EPR spectra of the defect on the three inequivalent lattice sites were resolved and attributed to optical transitions between photon energies of 999 and 1075 meV by MCDA-EPR. The resolved hyperfine structure indicates the presence of one single carbon nucleus and several silicon ligand nuclei. These experimental findings are interpreted with help of total energy and spin density data obtained from the standard local-spin density approximation of the density-functional theory, using relaxed defect geometries obtained from the self-consistent charge density-functional theory based tight binding scheme. We have checked several defect models of which only the photoexcited spin triplet state of the carbon antisite–carbon vacancy pair (CSi-VC) in the doubly positive charge state can explain all experimental findings. We propose that the (CSi-VC) defect is formed from the isolated silicon vacancy as an annealing product by the movement of a carbon neighbor into the vacancy

Determination of sub-ppb epichlorohydrin levels in water by on-line solid-phase extraction liquid chromatography/tandem mass spectrometry

A new sensitive and selective method based on on-line solid-phase extraction (SPE) coupled to liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) using a triple quadrupole mass spectrometer has been developed for the determination of epichlorohydrin (ECH) in different types of water samples. ECH is not easily determined directly by ESI-MS as it is not readily ionized, and it has a low molecular mass and high polarity. Thus, prior derivatization of ECH was necessary, employing 3,5-difluorobenzylamine as a derivatizing agent with Fe(III) as a catalyst. In order to achieve accurate quantification, correcting for matrix effects, losses in the derivatization process and instrumental deviations, isotope labelled ECH (ECH-d(5)) was added as an internal standard (IS) to the water samples. The method was validated based on European SANCO guidelines using drinking and other types of treated water spiked at two concentration levels (0.1 and 1.0 microg/L), the lower level having been established as the limit of quantification (LOQ) of the method. Satisfactory accuracy (recoveries between 70 and 103%), precision (RSD 0.99) were obtained. The limit of detection (LOD) was set up at 0.03 microg/L. The method was applied to different water samples (drinking water and water samples collected from a municipal treatment water plant). In order to enhance confidence, five selected reaction monitoring (SRM) transitions were acquired, thus obtaining a simultaneous reliable quantification and identification of ECH in water, even at sub-ppb level

Chromosomes are predominantly located randomly with respect to each other in interphase human cells

To test quantitatively whether there are systematic chromosome–chromosome associations within human interphase nuclei, interchanges between all possible heterologous pairs of chromosomes were measured with 24-color whole-chromosome painting (multiplex FISH), after damage to interphase lymphocytes by sparsely ionizing radiation in vitro. An excess of interchanges for a specific chromosome pair would indicate spatial proximity between the chromosomes comprising that pair. The experimental design was such that quite small deviations from randomness (extra pairwise interchanges within a group of chromosomes) would be detectable. The only statistically significant chromosome cluster was a group of five chromosomes previously observed to be preferentially located near the center of the nucleus. However, quantitatively, the overall deviation from randomness within the whole genome was small. Thus, whereas some chromosome–chromosome associations are clearly present, at the whole-chromosomal level, the predominant overall pattern appears to be spatially random

The role of gender constancy in early gender development.

Kohlberg's (1966) hypothesis that the attainment of gender constancy motivates children to attend to gender norms was reevaluated by examining these links in relation to age. Ninety-four 3-to 7-year-old children were interviewed to assess whether and how constancy mediates age-related changes in gender-related beliefs. As expected, results indicated a general pattern of an increase in stereotype knowledge, the importance and positive evaluation of one's own gender category, and rigidity of beliefs between the ages of 3 and 5. Moreover, the stability phase, rather than full constancy, mediated some of these relations. After age 5, rigidity generally decreased with age, with relations primarily mediated by consistency. One of the most compelling yet controversial ideas in the gender literature is ''gender constancy.'' As proposed by Indeed, as reviewed recently Inconsistencies across studies may occur for various reasons. First, relations in very young children may sometimes be misleading because many young children appear to show a phase of ''pseudoconstancy'' (Emmerich, Goldman, Kirsh, & Sharabany, 1977; A second problem is that it remains unclear which stage of gender constancy drives children's reactions. In a recent review of the literature on relations between stage of gender constancy and responsiveness to gender-related information, gender consistency did not emerge as the crucial component A third problem is that gender development does not change in a linear fashion. For example, children's gender stereotypes appear to be held rigidly at approximately 5 years and then become more flexible Indeed, there has been theoretical debate about whether full constancy understanding should be associated with relatively high or low levels of rigidity. These alternative predictions are interesting in light of the literature on essentialistic thought (e.g., Gelman, 2003). Children's attempts to understand the implications of different essences are particularly important for social categories because individuals can belong to the categories and identify with them, and thus they have implications for ingroup and outgroup attitudes and behaviors. That is, it matters which features of categories are critically linked to such essences. For example, if children think that wearing pink, frilly dresses result from ''girlness,'' boys should avoid them and girls should love them. Once children learn that such features are not fundamental to being a boy or a girl (i.e., the gender consistency stage), however, adherence to these more superficial aspects of the category can be relinquished. Bem (1989) made this argument for why it makes sense to teach young children that genitals, not appearance or activities, are the critical distinctions between males and females. If this is true, higher levels of consistency understanding should be associated with less rigidity, supporting These observations suggest that a closer look at the effects of gender constancy is needed. This is important not only because of inconsistencies in prior research. Recent analyses of gender development have described a close connection between cognitive-developmental theory and other theories that emphasize the importance of children's emerging understanding of gender categories, namely, gender schema theories (e.g., The present study also examined whether different levels of gender constancy understanding might be related to different kinds of beliefs. To this end, multiple measures of stability, consistency, and gender-related beliefs were included. Children as young as 3 years of age were interviewed to provide us with the opportunity to capture the processes that occur at an early stage of gender constancy. Moreover, children representing a full span of 4 years, from early 3-yearolds to early 7-year-olds, were included in the sample so that possible curvilinear patterns of gender-related beliefs, posited earlier, could be examined. This age range was of particular interest because it has been identified as a period of rapid change in gender beliefs. The gender-belief measures used in this study examined knowledge of gender stereotypes and several types of attitudes about norm adherence, specifically, the degree of belief that violations are wrong, feelings about interacting with norm violators, degree of fear of turning into the other sex if one violates gender norms, and expectations about parents' and peers' attitudes toward norm violations. In addition, based on the recent convergence of categorization theories discussed earlier, an additional type of belief was examined. Many studies have documented how identification with a particular social category can promote a sense of belonging, connectedness, and increased positive evaluation of the group (see It was expected that children would show agerelated increases in knowledge of gender stereotypes and gender category identification (centrality and evaluation), as well as increasingly rigid attitudes about adhering to gender norms, at least until 5 years of age. It was further expected that increasing understanding of some aspects of gender constancy would mediate these beliefs (see Method Participants Participants were recruited from public and private schools in a large eastern city, as well as through university faculty and staff willing to have their children participate. More than 90% of the children were White, with a small number of Asian, Latino, and African American children participating as well. Based on the demographic characteristics of the schools from which most of the children in this study were recruited, the majority of children were from middle-to upper-middle-class backgrounds. Ninetyfour children ranging in age from 3.13 to 7.30 years (M 5 5.14) were interviewed (48 girls, 46 boys). For most of the analyses, children were split into a younger (22 boys, 20 girls; M 5 4.08) and older (24 boys, 28 girls; M 5 6.00) cohort. Procedures Children were interviewed in two sessions at the university or in their schools, depending on the arrangements of the individual teachers and parents. Questionnaires were administered to participants in a set order designed to minimize possible effects of reactivity across measures. Interviewers-five female and one male-were all trained in the standardized administration of all measures (see Gender-Constancy Measures An interview derived from previously validated measures was the primary way we assessed level of gender constancy attainment Stability. Children's attainment of the stability stage was evaluated using two methods. The first part of the measure consisted of seven forced-choice questions based on prior gender constancy measures, as described previously. Of the seven forced-choice questions, three referred to the participant (e.g., ''When you grow up, will you be a man or a woman?'') and four referred to a male or female target (e.g., ''When this grown-up was little, was this grown-up really a girl or really a boy?''). The second part of this measure was based on a procedure originally developed by Children's responses to the open-ended consistency probes were recorded verbatim. Correct responses were then scored according to the coding scheme developed by The coding of open-ended rationales was completed by two judges who were blind to the age of the child, and interjudge reliability was high (average kappa 5 .96 for five questions collapsed, omitting the ''no response/unscorable'' code). Items were scored as correct only if the initial forced-choice question was answered correctly and the open-ended response was scored as indicating true constancy. In addition to these five items, a supplementary set of six forced-choice consistency questions was administered to all children. These questions were worded differently from those included in the standard interview measure, focusing explicitly on the act of transformation. Specifically, these questions focused on transformations involving the following: others' and personal appearance (e.g., ''If a boy wore nail polish, would he become a girl?''), and others' and personal activity choice (e.g., ''If you played with baby dolls right now, would you be a boy or girl?''). To score these items, 1 point was awarded for each correct answer. Preliminary analyses indicated that this subscale did not demonstrate the problematic relationship with age found with the standard forced-choice interview method scale, suggesting that an explicit emphasis on gender transformation is another way to avoid the effects of pseudoconstancy. In addition, this scale correlated significantly with the standard interview scale when the open-ended responses were taken into account (r 5 .35. p , .01). Therefore, the 11 total questions were combined into a single scale with a possible range of scores from 0 to 11 (alpha 5 .85, M 5 4.53, SD 5 2.88). Belief Variables Children were asked a series of questions assessing their knowledge and feelings about gender, as well as how important it was that they and others adhere to Gender Constancy 1125 gender norms. Several of these were part of a series of related questions based on the prior literature (e.g., Knowledge: Who usually wears nail polish, boys or girls? Rule-based rigidity: Is it wrong for boys to wear nail polish?; Would it be OK for a boy to wear nail polish if he didn't get into trouble and nobody laughed? Self-rigidity: Would you like to be friends with a boy who wears nail polish?; Would you like to go to a school where boys were allowed to wear nail polish? Fear of changing sex: [lead-in question: Do you wear nail polish?] Are you afraid you would become a girl if you wore nail polish? (for boys only) Knowledge. Children were asked which sex usually participates in each of five highly gender-typed behaviors: wears barrettes, wears nail polish, is strong, plays with dolls, and plays with trucks. Although more items about stereotyped knowledge were originally included in the interview, some had to be dropped because virtually all the children already knew them (e.g., shaves head) or they were not stereotyped as male or female typical (e.g., cooks). Responses to the five items were scored as number correct and converted to proportions. This was done to compare results across dependent variables, which were all transformed to a 0 to 1 scale. Thus, knowledge had a possible range of 0 to 1, indicating the proportion of the five items correct (alpha 5 .53). Centrality/evaluation. A measure of identification with one's gender group was developed based on prior research with adults (e.g., Rule-based rigidity. This scale, adapted from prior research (e.g., Self-rigidity. Children's attitudes about others who participate in or condone gender-atypical behavior were measured by their responses to eight questions. Two questions were asked in reference to the four target behaviors described earlier: Would the child want to be friends with someone who performed the particular cross-sex transgression? Would the child want to go to a school where the particular cross-sex transgression was allowed?'' Each response indicating a rigid approach to gender norms was given 1 point, and each response indicating a flexible approach was given 0 points. Scores across all questions were then averaged and transformed to a scale ranging from 0 to 1 (alpha 5 .89, M 5 .65, SD 5 .36). Fear of changing sex. Fear of physical repercussions for cross-sex transgressions was assessed with two forced-choice questions regarding children's fear of turning into the other sex if they were to engage in a sex-atypical behavior. Children were asked one 1126 Ruble et al. question for each of two other-sex stimuli (wearing nail polish and playing with baby dolls for boys; shaving one's head and playing with trucks for girls). The total score for each child was an average of the scores for their two responses, transformed to a scale from 0 to 1 (M 5 .42, SD 5 .42). As boys and girls were asked about different sets of stimuli, separate alphas were calculated (boys: alpha 5 .61; girls: alpha 5 .59). Peer and parent rigidity. These measures were based on prior research on children's fear of being sanctioned for norm violations (e.g., Children were shown each pair of toys and asked what would happen if they chose one of the crossgender toys placed in front of them and what their parents and friends might say in response. Two forced-choice questions were asked next, and they constitute the measures used in the present study: ''Would your friends (parents) be angry? Would they make fun of you?'' These questions were asked about two toys [dolls and tea sets for boys; trucks and dinosaurs for girls]. Thus, there were four scores for each participant, which were averaged, resulting in a score from 0 to 1 that represented the overall percentage of rigid responses, with a higher score indicating higher rigidity (peer measure: M 5 .35, SD 5 .35; parent measure: M 5 .15, SD 5 .28). Alphas for girls were: peers 5 .82 and parents 5 .73. Alphas for boys were: peers 5 .60 and parents 5 .74. Results The major purpose of this study was to examine agerelated changes in gender-related beliefs and their relations to the stages of gender constancy in children. First, we investigated how each variable related to age, both graphically and in zero-order correlations. Next, we focused on mediation and moderation analyses of the effects of constancy on gender beliefs using regression analyses

Paramagnetic signature of microcrystalline silicon carbide

Abstract. The most important challenge on the way to optimized solar cells is to make the thickness of the individual layers smaller than the diffusion length of the charge carriers, in order to keep the collection efficiency close to unity. Here, we propose ß-SiC microcrystals grown by a sol-gel based process as a promising acceptor material. The samples are characterized by optical spectroscopy and electron paramagnetic resonance (EPR). With the help of band structures for selected surface states calculated in the framework of density functional theory (DFT) a possible scenario for the observed acceptor process is discussed

Colloidal suspensions in modulated light fields

Periodically-modulated potentials in the form of light fields have previously been applied to induce reversible phase transitions in dilute colloidal systems with long-range interactions. Here we investigate whether similar transitions can be induced in very dense systems, where inter-particle contacts are important. Using microscopy we show that particles in such systems are indeed strongly affected by modulated potentials. We discuss technical aspects relevant to generating the light-induced potentials and to imaging simultaneously the particles. We also consider what happens when the particle size is comparable with the modulation wavelength. The effects of selected modulation wavelengths as well as pure radiation pressure are illustrated.Comment: Accepted by J. Phys.: Condens. Matter, CODEF II Special Issue. 23 pages, 12 figure