1,060 research outputs found

    Better in the dark: two Mediterranean amphibians synchronize reproduction with moonlit nights

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    In Amphibians, both positive and negative correlations between activity and full moon phase have been observed. In this study, we present data for two anuran species (<i>Hyla intermedia</i> and <i>Rana dalmatina</i>) studied in a hilly Mediterranean area of central Italy. We analysed, in a two-year survey, the relationships between the number of egg clutches laid each night and the moon phases by means of circular statistics. Moreover, the studied species exhibited clear oviposition site selection behaviour influenced, at least in <i>H. intermedia</i>, by moon phases. We observed the occurrence of an avoidance effect by amphibians for oviposition and specific egg-laying behaviour during moon phases around the full moon. This apparent lunar phobia was evident in both species when yearly data were pooled. On the other hand, while this pattern continued to be also evident in <i>H. intermedia</i> when single years were considered, in <i>R. dalmatina</i> it stood just in one year of study. Nonetheless, during cloudy nights, when moonlight arriving on the ground was low, the frogs' behaviour was similar to that observed in new moon phases. We interpreted the observed pattern as an anti-predatory strategy. Overall, comparisons between our own study and previous research suggest that there was insufficient evidence to establish any unequivocal patterns and that further research in this regard is needed

    Focusing inversion technique applied to radar tomographic data

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    Traveltime tomography is a very effective tool to reconstruct acoustic, seismic or electromagnetic wave speed distribution. To infer the velocity image of the medium from the measurements of first arrivals is a typical example of ill-posed problem. In the framework of Tikhonov regularization theory, in order to replace an ill-posed problem by a well-posed one and to get a unique and stable solution, a stabilizing functional (stabilizer) has to be introduced. The stabilizer selects the desired solution from a class of solutions with a specific physical and/or geometrical property; e.g., the existence of sharp boundaries separating media with different petrophysical parameters. Usually stabilizers based on maximum smoothness criteria are used during the inversion process; in these cases the solutions provide smooth images which, in many situations, do not describe the examined objects properly. Recently a new algorithm of direct minimization of the Tikhonov parametric functional with minimum support stabilizer has been introduced; it produces clear and focused images of targets with sharp boundaries. In this research we apply this new technique to real radar tomographic data and we compare the obtained result with the solution generated by the more traditional minimum norm stabilizer.Comment: 4 pages, 1 figur

    Spread-ing Uncertainty, Shrinking Birth Rates: A Natural Experiment for Italy

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    Many previous studies have documented the procyclicality of fertility to business cycles or labour market indicators in Western countries. However, part of the recent fertility decline witnessed since the Great Recession has been left unexplained by traditional measures. The present study advances the notion that birth postponement might have accelerated in response to rising uncertainty, which fuelled negative expectations and declining levels of confidence about the future. To provide empirical support for the causal effect of perceived uncertainty on birth rates, we focus on Italy’s sovereign debt crisis of 2011–2012 as a natural experiment. Perceived uncertainty is measured using Google trends for the term ‘spread’—which acted as somewhat of a barometer for the crisis both in the media and everyday conversations—to capture the general public’s degree of concern about the stability of Italian public finances. A regression discontinuity in time identifies the effect of perceived uncertainty on birth rates in Italy as a drop between 1.5% and 5%, depending on model specification

    Multiple-point statistical simulation for hydrogeological models: 3D training image development and conditioning strategies

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    Most studies about the application of geostatistical simulations based on multiple-point statistics (MPS) to hydrogeological modelling focus on relatively fine-scale models and concentrate on the estimation of facies-level, structural uncertainty. Much less attention is paid to the use of input data and optimal construction of training images. For instance, even though the training image should capture a set of spatial geological characteristics to guide the simulations, the majority of the research still relies on 2D or quasi-3D training images. In the present study, we demonstrate a novel strategy for 3D MPS modelling characterized by: (i) realistic 3D training images, and (ii) an effective workflow for incorporating a diverse group of geological and geophysical data sets. The study covers an area of 2810 km2 in the southern part of Denmark. MPS simulations are performed on a subset of the geological succession (the lower to middle Miocene sediments) which is characterized by relatively uniform structures and dominated by sand and clay. The simulated domain is large and each of the geostatistical realizations contains approximately 45 million voxels with size 100 m × 100 m × 5 m. Data used for the modelling include water well logs, high-resolution seismic data, and a previously published 3D geological model. We apply a series of different strategies for the simulations based on data quality, and develop a novel method to effectively create observed sand/clay spatial trends. The training image is constructed as a small 3D voxel model covering an area of 90 km2. We use an iterative training image development strategy and find that even slight modifications in the training image create significant changes in simulations. Thus, the study underlines that it is important to consider both the geological environment, and the type and quality of input information in order to achieve optimal results from MPS modelling. In this study we present a possible workflow to build the training image and effectively handle different types of input information to perform large-scale geostatistical modellin

    Unravelling work drive: A comparison between workaholism and overcommitment

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    Workaholism and overcommitment are often used as interchangeable constructs describing an individual’s over-involvement toward their own job. Employees with high levels in both constructs are characterized by an excessive effort and attachment to their job, with the incapability to detach from it and negative consequences in terms of poor health and job burnout. However, few studies have simultaneously measured both constructs, and their relationships are still not clear. In this study, we try to disentangle workaholism and overcommitment by comparing them with theoretically related contextual and personal antecedents, as well as their health consequences. We conducted a nonprobability mixed mode research design on 133 employees from different organizations in Italy using both self-and other-reported measures. To test our hypothesis that workaholism and overcommitment are related yet different constructs, we used partial correlations and regression analyses. The results confirm that these two constructs are related to each other, but also outline that overcommitment (and not workaholism) is uniquely related to job burnout, so that overcommitment rather than workaholism could represent the true negative aspect of work drive. Additionally, workaholism is more related to conscientiousness than overcommitment, while overcommitment shows a stronger relationship with neuroticism than workaholism. The theoretical implications are discussed

    Serum or Plasma (and Which Plasma), That Is the Question

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    Serum or Plasma (and Which Plasma), That Is the Question

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    Blood derivatives are the biofluids of choice formetabolomic clinical studies since blood can be collected with lowinvasiveness and is rich in biological information. However, the choiceof the blood collection tubes has an undeniable impact on the plasmaand serum metabolic content. Here, we compared the metabolomicand lipoprotein profiles of blood samples collected at the same timeand place from six healthy volunteers but using different collectiontubes (each enrolled volunteer provided multiple blood samples at adistance of a few weeks/months): citrate plasma, EDTA plasma, andserum tubes. All samples were analyzed via nuclear magnetic resonancespectroscopy. Several metabolites showed statistically significantalterations among the three blood matrices, and also metabolites'correlations were shown to be affected. The effects of blood collectiontubes on the lipoproteins'profiles are relevant too, but less marked. Overcoming the issue associated with different blood collectiontubes is pivotal to scale metabolomics and lipoprotein analysis at the level of epidemiological studies based on samples frommulticenter cohorts. We propose a statistical solution, based on regression, that is shown to be efficient in reducing the alterationsinduced by the different collection tubes for both the metabolomic and lipoprotein profile

    Imaging of mandibular fractures: a pictorial review

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    Mandibular fractures are among the most common maxillofacial fractures observed in emergency rooms and are mainly caused by road accidents. The clinical features of mandibular fractures include malocclusion and loss of mandibular function. Panoramic radiography is usually limited to isolated lesions, whereas computed tomography is the tool of choice for all other facial traumatic events. No reference standard classification system for the different types of mandibular fractures is defined. Therapeutic options include a conservative approach or surgical treatment based on the anatomic area and the severity of fracture. The main purpose of this pictorial review is to illustrate a practical description of the pathophysiology of mandibular fractures and describe both the imaging techniques to recognise them and the therapeutic indications
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