Factorial structure and reliability of a perceived influence on selection of a specialized plan of studies, IPEP, in secondary school students of Chillan, Chile

To evaluate these factors, the scale of perceived influences on the election of a specialized plan of studies, IPEP, was built and in this study its factorial structure and reliability were evaluated. The instrument was applied to 115 students, chosen by quote sampling. They were students of a subsidized private secondary school from the city of Chillan, Chile. An exploratory factorial analysis identified eight factors in the scale IPEP: Academic projection, Personal development, Maintenance of the social environment, Academic requirements, Satisfaction of others' expectations, Vocational information, Image of the plan and Family pressure. The results present an initial factorial structure, that empirically and theoretically adequate, whose factors were reliable and conceptually useful. These factors distinguish psychogenic and sociogenic aspects of the vocational process, and allow to initiate diagnostic and investigative actions in relation to this early vocational election that is established in secondary schools of the Chilean educational system

Factorial structure and reliability of a perceived influence on selection of a specialized plan of studies, IPEP, in secondary school students of Chillan, Chile

To evaluate these factors, the scale of perceived influences on the election of a specialized plan of studies, IPEP, was built and in this study its factorial structure and reliability were evaluated. The instrument was applied to 115 students, chosen by quote sampling. They were students of a subsidized private secondary school from the city of Chillan, Chile. An exploratory factorial analysis identified eight factors in the scale IPEP: Academic projection, Personal development, Maintenance of the social environment, Academic requirements, Satisfaction of others' expectations, Vocational information, Image of the plan and Family pressure. The results present an initial factorial structure, that empirically and theoretically adequate, whose factors were reliable and conceptually useful. These factors distinguish psychogenic and sociogenic aspects of the vocational process, and allow to initiate diagnostic and investigative actions in relation to this early vocational election that is established in secondary schools of the Chilean educational system

Factorial structure and reliability of a perceived influence on selection of a specialized plan of studies, IPEP, in secondary school students of Chillan, Chile

To evaluate these factors, the scale of perceived influences on the election of a specialized plan of studies, IPEP, was built and in this study its factorial structure and reliability were evaluated. The instrument was applied to 115 students, chosen by quote sampling. They were students of a subsidized private secondary school from the city of Chillan, Chile. An exploratory factorial analysis identified eight factors in the scale IPEP: Academic projection, Personal development, Maintenance of the social environment, Academic requirements, Satisfaction of others' expectations, Vocational information, Image of the plan and Family pressure. The results present an initial factorial structure, that empirically and theoretically adequate, whose factors were reliable and conceptually useful. These factors distinguish psychogenic and sociogenic aspects of the vocational process, and allow to initiate diagnostic and investigative actions in relation to this early vocational election that is established in secondary schools of the Chilean educational system

Social cleavages and electoral support in Turkey -- toward convergence?

Studies on Western democracies have shown that deep-seated social cleavages stabilize the electoral behavior and thus reduce electoral volatility. But how do social cleavages affect a party system that is undergoing democratic consolidation, such as in Turkey? In this study, investigations were carried out on long- and short-term relationships between social cleavages (religiosity, ethnicity, and sectarism) and electoral volatility in Turkey during the 1961-2002 period. Cross-sectional multiple regressions were applied to electoral and demographic data at the provincial level. The results showed that in the long-term, social cleavages on the whole have increased volatility rather than reduced it. The cleavage-volatility relationship, however, has changed over time. Repeated elections have mitigated the volatile effect of social cleavages on the voting behavior, as political parties have become more representative of the existent social cleavages.

The anatomy of urban social networks and its implications in the searchability problem

The appearance of large geolocated communication datasets has recently increased our understanding of how social networks relate to their physical space. However, many recurrently reported properties, such as the spatial clustering of network communities, have not yet been systematically tested at different scales. In this work we analyze the social network structure of over 25 million phone users from three countries at three different scales: country, provinces and cities. We consistently find that this last urban scenario presents significant differences to common knowledge about social networks. First, the emergence of a giant component in the network seems to be controlled by whether or not the network spans over the entire urban border, almost independently of the population or geographic extension of the city. Second, urban communities are much less geographically clustered than expected. These two findings shed new light on the widely-studied searchability in self-organized networks. By exhaustive simulation of decentralized search strategies we conclude that urban networks are searchable not through geographical proximity as their country-wide counterparts, but through an homophily-driven community structure.

Structure and function in rhodopsin: Rhodopsin mutants with a neutral amino acid at E134 have a partially activated conformation in the dark state*

The Glu-134–Arg-135 residues in rhodopsin, located near the cytoplasmic end of the C helix, are involved in G protein binding, or activation, or both. Furthermore, the charge-neutralizing mutation Glu-134 to Gln-134 produces hyperactivity in the activated state and produces constitutive activity in opsin. The Glu/Asp-Arg charge pair is highly conserved in equivalent positions in other G protein-coupled receptors. To investigate the structural consequences of charge-neutralizing mutations at Glu-134 and Arg-135 in rhodopsin, single spin-labeled side chains were introduced at sites in the cytoplasmic domains of helices C (140), E (227), F (250), or G (316) to serve as “molecular sensors” of the local helix bundle conformation. In each of the spin-labeled rhodopsins, a Gln substitution was introduced at either Glu-134 or Arg-135, and the electron paramagnetic resonance spectrum of the spin label was used to monitor the structural response of the helix bundle. The results indicate that a Gln substitution at Glu-134 induces a photoactivated conformation around helices C and G even in the dark state, an observation of potential relevance to the hyperactivity and constitutive activity of the mutant. In contrast, little change is induced in helix F, which has been shown to undergo a dominant motion upon photoactivation. This result implies that the multiple helix motions accompanying photoactivation are not strongly coupled and can be induced to take place independently. Gln substitution at Arg-135 produces only minor structural changes in the dark- or light-activated conformation, suggesting that this residue is not a determinant of structure in the regions investigated, although it may be functionally important.

ARF Is Required for Maintenance of Yeast Golgi and Endosome Structure and Function

ADP ribosylation factor (ARF) is thought to play a critical role in recruiting coatomer (COPI) to Golgi membranes to drive transport vesicle budding. Yeast strains harboring mutant COPI proteins exhibit defects in retrograde Golgi to endoplasmic reticulum protein transport and striking cargo-selective defects in anterograde endoplasmic reticulum to Golgi protein transport. To determine whether arf mutants exhibit similar phenotypes, the anterograde transport kinetics of multiple cargo proteins were examined in arf mutant cells, and, surprisingly, both COPI-dependent and COPI-independent cargo proteins exhibited comparable defects. Retrograde dilysine-mediated transport also appeared to be inefficient in the arf mutants, and coatomer mutants with no detectable anterograde transport defect exhibited a synthetic growth defect when combined with arf1Δ, supporting a role for ARF in retrograde transport. Remarkably, we found that early and medial Golgi glycosyltransferases localized to abnormally large ring-shaped structures. The endocytic marker FM4–64 also stained similar, but generally larger ring-shaped structures en route from the plasma membrane to the vacuole in arf mutants. Brefeldin A similarly perturbed endosome morphology and also inhibited transport of FM4–64 from endosomal structures to the vacuole. Electron microscopy of arf mutant cells revealed the presence of what appear to be hollow spheres of interconnected membrane tubules which likely correspond to the fluorescent ring structures. Together, these observations indicate that organelle morphology is significantly more affected than transport in the arf mutants, suggesting a fundamental role for ARF in regulating membrane dynamics. Possible mechanisms for producing this dramatic morphological change in intracellular organelles and its relation to the function of ARF in coat assembly are discussed.

Domain structure and dynamics in the helical filaments formed by RecA and Rad51 on DNA

Both the bacterial RecA protein and the eukaryotic Rad51 protein form helical nucleoprotein filaments on DNA that catalyze strand transfer between two homologous DNA molecules. However, only the ATP-binding cores of these proteins have been conserved, and this same core is also found within helicases and the F1-ATPase. The C-terminal domain of the RecA protein forms lobes within the helical RecA filament. However, the Rad51 proteins do not have the C-terminal domain found in RecA, but have an N-terminal extension that is absent in the RecA protein. Both the RecA C-terminal domain and the Rad51 N-terminal domain bind DNA. We have used electron microscopy to show that the lobes of the yeast and human Rad51 filaments appear to be formed by N-terminal domains. These lobes are conformationally flexible in both RecA and Rad51. Within RecA filaments, the change between the “active” and “inactive” states appears to mainly involve a large movement of the C-terminal lobe. The N-terminal domain of Rad51 and the C-terminal domain of RecA may have arisen from convergent evolution to play similar roles in the filaments.

Structure and conformational changes of DNA topoisomerase II visualized by electron microscopy.

Type II DNA topoisomerases, which create a transient gate in duplex DNA and transfer a second duplex DNA through this gate, are essential for topological transformations of DNA in prokaryotic and eukaryotic cells and are of interest not only from a mechanistic perspective but also because they are targets of agents for anticancer and antimicrobial chemotherapy. Here we describe the structure of the molecule of human topoisomerase II [DNA topoisomerase (ATP-hydrolyzing), EC 5.99.1.3] as seen by scanning transmission electron microscopy. A globular approximately 90-angstrom diameter core is connected by linkers to two approximately 50-angstrom domains, which were shown by comparison with genetically truncated Saccharomyces cerevisiae topoisomerase II to contain the N-terminal region of the approximately 170-kDa subunits and that are seen in different orientations. When the ATP-binding site is occupied by a nonhydrolyzable ATP analog, a quite different structure is seen that results from a major conformational change and consists of two domains approximately 90 angstrom and approximately 60 angstrom in diameter connected by a linker, and in which the N-terminal domains have interacted. About two-thirds of the molecules show an approximately 25 A tunnel in the apical part of the large domain, and the remainder contain an internal cavity approximately 30 A wide in the large domain close to the linker region. We propose that structural rearrangements lead to this displacement of an internal tunnel. The tunnel is likely to represent the channel through which one DNA duplex, after capture in the clamp formed by the N-terminal domains, is transferred across the interface between the enzyme's subunits. These images are consistent with biochemical observations and provide a structural basis for understanding the reaction of topoisomerase II.

Perceived social support in a large community sample - Age and sex differences

Background. The positive health and wellbeing effects of social support have been consistently demonstrated in the literature since the late 1970s. However, a better understanding of the effects of age and sex is required. Method. We examined the factor structure and reliability of Kessler's Perceived Social Support (KPSS) measure in a community-based sample that comprised younger and older adult cohorts from the Australian Twin Registry (ATR), totalling 11,389 males and females aged 18-95, of whom 887 were retested 25 months later. Results. Factor analysis consistently identified seven factors: support from spouse, twin, children, parents, relatives, friends and helping support. Internal reliability for the seven dimensions ranged from 0.87 to 0.71 and test-retest reliability ranged from 0.75 to 0.48. Perceived support was only marginally higher in females. Age dependencies were explored. Across the age range, there was a slight decline (more marked in females) in the perceived support from spouse, parent and friend, a slight increase in perceived relative and helping support for males but none for females, a substantial increase in the perceived support from children for males and females and a negligible decline in total KPSS for females against a negligible increase for males. The perceived support from twin remained constant. Females were more likely to have a confidant, although this declined with age whilst increasing with age for males. Conclusions. Total scores for perceived social support conflate heterogeneous patterns on sub-scales that differ markedly by age and sex. Our paper describes these relationships in detail in a very large Australian sample.

Perceptions of the intergroup structure and anti-Asian prejudice among white Australians

Subjective intergroup beliefs and authoritarianism were assessed in a field study (N=255) of White Australians' anti-Asian stereotyping and prejudice. A social identity analysis of intergroup prejudice was adopted, such that perceptions of the intergroup structure (instability, permeability, legitimacy and higher ingroup status) were proposed as predictors of higher prejudice (blatant and covert) and less favorable stereotyping. Consistent with the social identity approach, both independent and interacting roles for sociostructural predictors of Anti-Asian bias were observed, even after demographic and personality variables were controlled. For example, perceived legitimacy was associated with higher prejudice when White Australians' status position relative to Asian Australians was valued. Moreover, when participants evaluated Whites' position as unstable and high status or legitimate, perceptions of permeable intergroup boundaries were associated with anti-Asian bias. The present findings demonstrate status protection responses in advantaged group members in a field setting, lending weight to the contention that perceptions of sociostructural threat interact to predict outgroup derogation. Implications for theories of intergroup relations are discussed.