3,583 research outputs found

    Insights on the changing dynamics of cemetery use in the neolithic and chalcolithic of southern Portugal. Radiocarbon dating of Lugar do Canto Cave (Santarém)

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    Lugar do Canto Cave is one of the most relevant Neolithic burial caves in Portugal given not only its extraordinary preservation conditions at the time of discovery but also the quality of the field record obtained during excavation. Its material culture immediately pointed to a Middle Neolithic cemetery but recent radiocarbon determinations also allowed the recognition of an apparent two step phasing of its use within the period (ca. 4000-3400 cal BC): an older one characterized by a single burial and a later reoccupation as a collective necropolis. Comparisons with other well-dated cave cemeteries in Southern Portugal permitted the recognition of changing funerary practices and strategies of cemetery use during the later stages of the Neolithic and the Chalcolithic: 1) ca. 3800 cal BC as the possible turning point from the practice of individual to collective burials; 2) alternating periods of intensive use and deliberate abandonment of cemeteries (evidenced by their intentional closure). Research avenues to investigate the social organization and ideological context underlying these aspects of the Neolithic communities in greater depth are tentatively pointed out in this paper.FEDER funds through the Programa Operacional Factores de Competividade (COMPETE

    Topological Equivalence and Similarity in Multi-Representation Geographic Databases

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    Geographic databases contain collections of spatial data representing the variety of views for the real world at a specific time. Depending on the resolution or scale of the spatial data, spatial objects may have different spatial dimensions, and they may be represented by point, linear, or polygonal features, or combination of them. The diversity of data that are collected over the same area, often from different sources, imposes a question of how to integrate and to keep them consistent in order to provide correct answers for spatial queries. This thesis is concerned with the development of a tool to check topological equivalence and similarity for spatial objects in multi-representation databases. The main question is what are the components of a model to identify topological consistency, based on a set of possible transitions for the different types of spatial representations. This work develops a new formalism to model consistently spatial objects and spatial relations between several objects, each represented at multiple levels of detail. It focuses on the topological consistency constraints that must hold among the different representation of objects, but it is not concerned about generalization operations of how to derive one representation level from another. The result of this thesis is a?computational tool to evaluate topological equivalence and similarity across multiple representations. This thesis proposes to organize a spatial scene -a set of spatial objects and their embeddings in space- directly as a relation-based model that uses a hierarchical graph representation. The focus of the relation-based model is on relevant object representations. Only the highest-dimensional object representations are explicitly stored, while their parts are not represented in the graph

    TMS application in both health and disease

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    Transcranial magnetic stimulation (TMS) can be useful for therapeutic purposes for a variety of clinical conditions. Numerous studies have indicated the potential of this noninvasive brain stimulation technique to recover brain function and to study physiological mechanisms. Following this line, the articles contemplated in this Research Topic show that this field of knowledge is rapidly expanding and considerable advances have been made in the last few years. There are clinical protocols already approved for Depression (and anxiety comorbid with major depressive disorder), Obsessive compulsive Disorder (OCD), migraine headache with aura, and smoking cessation treatment but many studies are concentrating their efforts on extending its application to other diseases, e.g., as a treatment adjuvant. In this Research Topic we have the example of using TMS for pain, post-stroke depression, or smoking cessation, but other diseases/injuries of the central nervous system need attention (e.g., tinnitus or the surprising epilepsy). Further, the potential of TMS in health is being explored, in particular regarding memory enhancement or the mapping of motor control regions, which might also have implications for several diseases. TMS is a non-invasive brain stimulation technique that can be used for modulating brain activation or to study connectivity between brain regions. It has proven efficacy against neurological and neuropsychiatric illnesses but the response to this stimulation is still highly variable. Research works devoted to studying the response variability to TMS, as well as large-scale studies demonstrating its efficacy in different sub-populations, are therefore of utmost importance. In this editorial, we summarize the main findings and viewpoints detailed within each of the 12 contributing articles using TMS for health and/or disease applications.publishe

    Clarifying the Role of Social Support in the Relationship between Stressors and Strains at Work: The Effect of Self-Construals

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    Practitioners and researchers often focus on social support to allay occupational stress, despite inconsistent results from empirical studies. This longitudinal study examined the impact of nurses’ self-construals on the effect of social support on the relationship between stressors and outcomes, based on research showing that people in individualistic and collectivistic cultures perceive supervisor and coworker support differently and research showing culture is internalized as self-construals. The aim of the study was to identify circumstances in which social support mitigates stress. Survey data were collected at two points in time (about four weeks apart), from 139 nurses in two northern California hospitals, and subjected to hierarchical multiple regression and correlation analyses. Results showed that most models for direct effects of social support on outcomes were supported and none of the models for two-way interactions of support and stressors on outcomes were supported. However, self-construal did interact with social support and stressors but in the opposite direction of what was hypothesized. Coworker support aggravated the effect of role overload on anxiety for interdependents (reverse buffering) but not independents. Supervisor support aggravated the effect of role ambiguity on health and burnout for independents but mitigated it for interdependents (buffering). These findings, while opposing the hypotheses, still showed the importance of context in the role of social support on occupational stress and this role’s complexity

    Venture Capital as Human Resource Management

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    Venture capitalists add value to portfolio firms by obtaining and transferring information about senior managers across firms over time. Information transfer occurs on a significant scale and takes place both among a single venture capitalist%u2019s portfolio firms and between different venture capitalists%u2019 firms via a network of venture capitalists, which venture capitalists use to locate and relocate managers. Cross-sectional differences are associated with differences in the intensity with which venture capitalists network. The observable factors relevant in explaining the intensity with which venture capitalists network include: 1) the value of the information transmitted through the network, 2) the riskiness of the activities of portfolio firms, 3) the size of the venture capital fund, 4) the degree of difficulty in enticing executives to manage portfolio firms, and 5) the reputation of the venture capitalist for successfully recycling managers. These factors reflect costs and benefits to venture capitalists of participating in the network.
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