1,721,132 research outputs found
Browsing in geographic databases: an object-oriented approach
No full textAn interaction model for object-oriented geographic databases is presented. A browsing technique based on the model is outlined. The approach is uniform for navigating both the intensional and extensional part of the database. The proposed interaction model is flexible and is suitable for satisfying many purposes. It is able to satisfy users interested in getting a general idea about the contents of the database, as well as those with more specific tasks to accomplish. Depending on their requirements, users may control the degree of complexity of the information presented on the screen. Two basic criteria are adopted for browsing the database: logic adjacency and spatial adjacency between objects. Logic adjacency is determined by four conceptual links, while spatial adjacency is related to the two-dimensional (map-based) view of geographic entitie
An Object-Oriented Conceptual Model for the Representation of Geographic Information
No full textThe interest of the DP community towards geographic databases is large. The drawbacks of traditional database systems when used for handling unstructured data have been largely pointed out in the literature. At present, research efforts are concentrated on the investigation of the usability of the object-oriented approach for developing a new generation of powerful geographic database systems. The complexity of geographic systems, in terms of relationships to be modelled and operations to be performed on data, is well-known; therefore a conceptual analysis of the specific situation is a good strategy for handling the complexity of the implementation. The authors propose an object-oriented conceptual model tailored for organizing and representing basic map elements and their relationships, as well as operations of interest for the management of geographic data. The aim is to provide designers with a conceptual tool useful for organizing their knowledge about a geographic application in terms of basic concepts of the object-oriented paradigm, namely classes, instances, and method
A Spatial Data Model Underlying Human Interaction with Object-Oriented Spatial Databases
No full textIn geographic maps, objects are represented in a context extremely rich of relationships among them, either one-to-one or many-to-many. Unfortunately, all these relationships can not be directly represented in the database scheme. Nevertheless, it should be possible to show them to the user during the interaction. To manage this problem, the authors refer to a two-level database architecture with an object-oriented data model at the bottom level (the logic level), and an interaction model at the top level. The spatial data model given is an essential part of the interaction model. The spatial data model is a conceptual tool that enhances the object-oriented model with spatial relationships between objects. The basic objectives of the spatial data model are outlined: to point out the relationships among objects to be shown in the views, to define data structures suitable for navigating among database objects, and to provide a simple and powerful calculus for posing spatial queries against the databas
Sleep Quality, Insomnia Symptoms, and Depressive Symptomatology among Italian University Students before and during the Covid-19 Lockdown
Full text linkThe COVID-19 pandemic led world authorities to adopt extraordinary measures to coun-teract the spread of the virus. The Italian government established a national lockdown from 9 March to 3 May 2020, forcing people in their homes and imposing social distancing. During the pandemic emergency, university students emerged as a vulnerable category. Indeed, higher rates of sleep problems and mental disorders were reported in this population. However, these outcomes were derived from cross-sectional investigations adopting retrospective assessments. Retrospective evaluations suffer from different biases, putatively leading to erroneous outcomes. To overcome this limitation, we adopted a between-subject approach comparing a sample of 240 Italian undergraduate university students assessed in 2016 (mean age ± standard deviation, 20.39 ± 1.42, range 18–25; 80.42% females), with an age/gender-matched sample of university students assessed during the third week of lockdown in Spring 2020. We evaluated sleep quality, insomnia symptoms, and depressive symptomatology using validated questionnaires. We found worse sleep quality, a delayed bedtime, and more severe insomnia and depression symptoms in the students sampled under COVID-19 restrictive measures. We suggest paying special attention to this at-risk population during the current pandemic emergency and applying preventive and supportive interventions to limit the exacerbation of sleep and psychological problems
Sleeping under the waves: A longitudinal study across the contagion peaks of the COVID-19 pandemic in Italy
Full text linkAfter the March–April 2020 coronavirus disease 2019 (COVID-19) outbreak, a second contagion wave afflicted Europe in the autumn. The present study aimed to evaluate sleep health/patterns of Italians during this further challenging situation. A total of 2,013 Italians longitudinally participated in a web-based survey during the two contagion peaks of the COVID-19 outbreak. We investigated the risk factors for sleep disturbances during the second wave, and we compared sleep quality and psychological well-being between the two assessments (March–April and November–December 2020). Female gender, low education, evening chronotype, being a high-risk person for COVID-19 infection, reporting negative social or economic impact, and evening smartphone overuse predicted a higher risk of poor sleep and insomnia symptoms during the second wave. Advanced age, living with a high-risk person for COVID-19 infection, and having a relative/friend infected with COVID-19 before the prior 2 weeks were risk categories for poor sleep quality. Living with children, having contracted COVID-19 before the prior 2 weeks, being pessimistic about the vaccine and working in healthcare, were risk factors for insomnia symptoms. The follow-up assessment highlighted reduced insomnia symptoms and anxiety. Nevertheless, we found reduced sleep duration, higher daytime dysfunction, advanced bedtime and wake-up time, and a shift to morningness, confirming the alarming prevalence of poor sleepers (~60%) and severe depression (~20%) in a context of increased perceived stress. The present study showed a persistent impact of the COVID-19 pandemic on sleep and mental health. Large-scale interventions to counteract the chronicity and exacerbation of sleep and psychological disturbances are necessary, especially for the at-risk categories
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