841 research outputs found

    Modeling the role of voyaging in the coastal spread of the Early Neolithic in the West Mediterranean

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    The earliest dates for the West Mediterranean Neolithic indicate that it expanded across 2,500 km in about 300 y. Such a fast spread is held to be mainly due to a demic process driven by dispersal along coastal routes. Here, we model the Neolithic spread in the region by focusing on the role of voyaging to understand better the core elements that produced the observed pattern of dates. We also explore the effect of cultural interaction with Mesolithic populations living along the coast. The simulation study shows that (i) sea travel is required to obtain reasonable predictions, with a minimum sea-travel range of 300 km per generation; (ii) leapfrog coastal dispersals yield the best results (quantitatively and qualitatively); and (iii) interaction with Mesolithic people can assist the spread, but long-range voyaging is still needed to explain the archaeological pattern.info:eu-repo/semantics/publishedVersio

    Contracting externalities and multiple equilibria in sectors: Theory and evidence

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    We consider an economy where the production technology has constant returns to scale but where in the descentralized equilibrium there are aggregate increasing returns to scale. The result follows from a positive contracting externality among firms. If a firms is surrounded by more firms, employees have more opportunities outside their own firm. This improves employees' incentives to invest in the presence of ex post renegotiation at the firm level, at not cost. Our leading result is that if a region is sparsely populated or if the degree of development in the region is low enough, there are multiple equilibria in the level of sectorial employment. From the theoretical model we derive a non-linear first-order censored difference equation for sectoral employment. Our results are strongly consistent with the multiple equilibria hypothesis and the existence of a sectoral critical scale (below wich the sector follows a delocation process). The scale of the regions' population and the degree of development reduce the critical scale of the sector.Incomplete contracts, development, multiple equilibria, delocation trap

    Psychological Pathways to Paranoia and Psychotic-Like Experiences in Daily-Life : The Mediating Role of Distinct Affective Disturbances

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    Influential models of psychosis indicate that the impact of putative causal factors on positive symptoms might be explained partly through affective disturbances. We aimed to investigate whether pathways from stress and self-esteem to positive symptoms, as well as reversal pathways from symptoms to stress and self-esteem, were mediated through specific affective disturbances across the extended psychosis phenotype. Using experience sampling methodology, 178 participants (65 high-schizotypy, 74 at-risk mental state, and 39 first-episode psychosis) were assessed on levels of momentary stress, self-esteem, anxiety, sadness, psychotic-like experiences (PLE), and paranoia. Multilevel mediation models were fit to examine indirect effects of each of these pathways. Considering evidence of mediation, each indirect pathway will be combined in a single model to explore their relative contributions. Anxiety, sadness, and self-esteem mediated the pathways from stress to PLE and paranoia in daily-life. In the pathway to paranoia, sadness, and self-esteem showed larger contributions than anxiety. Pathways from self-esteem to PLE and paranoia were mediated by anxiety and sadness, the later showing a larger contribution. Pathways from symptoms to stress, but not from symptoms to self-esteem, were differently explained by emotional states; sadness lost its mediating effect and anxiety was the most important mediator. Few differences across groups were found. This study lends support to psychological models of psychosis that highlight the relevance of affective disturbances in the risk and expression of psychosis. Furthermore, specific influences of different negative emotional states were identified, which could enhance psychological treatments

    A brief questionnaire measure of multidimensional schizotypy predicts interview-rated symptoms and impairment

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    The present study employed structured diagnostic interviews to assess the construct validity of the brief version of the Multidimensional Schizotypy Scale (MSS-B), which was developed to assess positive, negative, and disorganized dimensions of schizotypy. It was hypothesized that the MSS-B subscales would be associated with differential patterns of symptoms and impairment, comparable to findings for the full-length MSS. A total of 177 young adults completed structured diagnostic interviews assessing symptoms and impairment. As hypothesized, MSS-B positive schizotypy was significantly associated with interview ratings of positive (psychotic-like) symptoms, as well as schizotypal and paranoid personality disorder traits. MSS-B negative schizotypy was associated with interview ratings of negative symptoms, as well as schizoid, paranoid, and schizotypal traits. Furthermore, negative schizotypy predicted Cluster A personality disorder diagnoses. MSS-B disorganized schizotypy was associated with interview ratings of disorganized symptoms. All three schizotypy dimensions were associated with impaired functioning. This was the first study to evaluate the validity of the MSS-B using interview measures, and the pattern of findings for each MSS-B subscale was closely comparable to the findings for the full-length MSS. Contrary to our hypothesis, cannabis use was largely unassociated with psychotic-like symptoms and did not moderate the expression of the schizotypy dimensions. The MSS-B has good psychometric properties, high concordance with the full-length MSS, and good construct validity. Thus, it appears to be a promising brief alternative to traditional schizotypy measures

    Study of the heat transfer during the alkaline treatment in the processing of Spanish Style green table olives

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    En este artículo se describe por primera vez a nivel industrial el aumento de temperatura que se produce en el interior de los tanques de elaboración durante la etapa de cocido. A partir del estudio de las características térmicas de la etapa de cocido se han podido determinar relaciones entre las variables que definen el proceso. Se ha demostrado que la temperatura al inicio del tratamiento de cocido influye en otras de las características del proceso como la duración de éste o la pendiente del aumento lineal de temperatura durante la etapa. El estudio establece que esta generación de calor puede provenir principalmente de las reacciones de hidrólisis alcalina que ocurren en el interior del fruto y, en menor proporción, de la dilución de la solución de hidróxido de sodio con el agua presente en la pulpa de las aceitunas

    Muscle protein waste in tumor-bearing rats is effectively antagonized by a beta 2-adrenergic agonist (clenbuterol). Role of the ATP-ubiquitin-dependent proteolytic pathway.

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    Tissue protein hypercatabolism (TPH) is a most important feature in cancer cachexia, particularly with regard to the skeletal muscle. The rat ascites hepatoma Yoshida AH-130 is a very suitable model system for studying the mechanisms involved in the processes that lead to tissue depletion, since it induces in the host a rapid and progressive muscle waste mainly due to TPH (Tessitore, L., G. Bonelli, and F. M. Baccino. 1987. Biochem. J. 241:153-159). Detectable plasma levels of tumor necrosis factor-alpha associated with marked perturbations in the hormonal homeostasis have been shown to concur in forcing metabolism into a catabolic setting (Tessitore, L., P. Costelli, and F. M. Baccino. 1993. Br. J. Cancer. 67:15-23). The present study was directed to investigate if beta 2-adrenergic agonists, which are known to favor skeletal muscle hypertrophy, could effectively antagonize the enhanced muscle protein breakdown in this cancer cachexia model. One such agent, i.e., clenbuterol, indeed largely prevented skeletal muscle waste in AH-130-bearing rats by restoring protein degradative rates close to control values. This normalization of protein breakdown rates was achieved through a decrease of the hyperactivation of the ATP-ubiquitin-dependent proteolytic pathway, as previously demonstrated in our laboratory (Llovera, M., C. García-Martínez, N. Agell, M. Marzábal, F. J. López-Soriano, and J. M. Argilés. 1994. FEBS (Fed. Eur. Biochem. Soc.) Lett. 338:311-318). By contrast, the drug did not exert any measurable effect on various parenchymal organs, nor did it modify the plasma level of corticosterone and insulin, which were increased and decreased, respectively, in the tumor hosts. The present data give new insights into the mechanisms by which clenbuterol exerts its preventive effect on muscle protein waste and seem to warrant the implementation of experimental protocols involving the use of clenbuterol or alike drugs in the treatment of pathological states involving TPH, particularly in skeletal muscle and heart, such as in the present model of cancer cachexia

    Suppression of glycogen synthesis as a treatment for Lafora disease: Establishing the window of opportunity

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    Lafora disease (LD) is a fatal adolescence-onset neurodegenerative condition. The hallmark of LD is the accumulation of aberrant glycogen aggregates called Lafora bodies (LBs) in the brain and other tissues. Impeding glycogen synthesis from early embryonic stages by genetic suppression of glycogen synthase (MGS) in an animal model of LD prevents LB formation and ultimately the pathological manifestations of LD thereby indicating that LBs are responsible for the pathophysiology of the disease. However, it is not clear whether eliminating glycogen synthesis in an adult animal after LBs have already formed would halt or reverse the progression of LD. Herein we generated a mouse model of LD with inducible MGS suppression. We evaluated the effect of MGS suppression at different time points on LB accumulation as well as on the appearance of neuroinflammation, a pathologic trait of LD models. In the skeletal muscle, MGS suppression in adult LD mice blocked the formation of new LBs and reduced the number of glycogen aggregates. In the brain, early but not late MGS suppression halted the accumulation of LBs. However, the neuroinflammatory response was still present, as shown by the levels of reactive astrocytes, microglia and inflammatory cytokines. Our results confirm that MGS as a promising therapeutic target for LD and highlight the importance of an early diagnosis for effective treatment of the disease

    Differential Test Performance in the American Educational System: The Impact of Race and Gender

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    Contrary to Herrnstein and Murray (1994) who claim that racial groups have different cognitive endowments and that these best explain differential test score achievements, our regression analyses document that there is less improvement in test scores per year of education for African-Americans and women. That is, the observed group test score differences do not appear to be due to racial cognitive differences but rather to other factors associated with group-linked experiences in the educational system. We found that 666 of the subjects in the Herrnstein-Murray database had actual IQ scores derived from school records. Using these as independent controls for IQ, we document that each of the test components that were the basis of the Herrnstein-Murray IQ scores was significantly associated with education level (p\u3c .001). Consequently, their IQ score appears to be an education-related measure rather than an IQ test, and thus challenges the validity of their analysis
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