4,713 research outputs found

    Health Data and Privacy in the Digital Era

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    In 2010, the social networking site Facebook launched a platform allowing private companies to request users’ permission to access personal data. Few users were aware of the platform, which was integrated into Facebook’s terms of service. In 2014, Cambridge Analytica, a UK-based political consulting firm, developed a data-harvesting app. That app prompted Facebook users to provide psychological profiles, including responses such as “I get upset easily” and “I have frequent mood-swings” as part of a “research project.” The Facebook platform allowed users to share their friends’ data as well, enabling Cambridge Analytica to access tens of millions of personal profiles, identifying voters’ political preferences. The controversy revealed risks to identifiable health data posed by social media and web services companies’ practices. After the Cambridge Analytica controversy, Facebook suspended a project that aimed to link data about users’ medical conditions with information about their social networks. Individuals often reveal detailed, sensitive health information online. Through wearable devices, social media posts, traceable web searches, and online patient communities, users generate large volumes of health data. Although some individuals participate in online patient forums and wellness information sharing apps under their own names, others participate via pseudonyms, assuming their privacy is preserved. Many users believe their data will be shared only with those they designate

    Interaction induced dimerization in zigzag single wall carbon nanotubes

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    We derive a low-energy effective model of metallic zigzag carbon nanotubes at half filling. We show that there are three important features characterizing the low-energy properties of these systems: the long-range Coulomb interaction, umklapp scattering and an explicit dimerization generated by interactions. The ratio of the dimerization induced gap and the Mott gap induced by the umklapp interactions is dependent on the radius of the nanotube and can drive the system through a quantum phase transition with SU(2)_1 quantum symmetry. We consider the physical properties of the phases on either side of this transition which should be relevant for realistic nanotubes.Comment: 8 pages, 5 figure

    Customer mobility and congestion in supermarkets

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    The analysis and characterization of human mobility using population-level mobility models is important for numerous applications, ranging from the estimation of commuter flows in cities to modeling trade flows between countries. However, almost all of these applications have focused on large spatial scales, which typically range between intra-city scales to inter-country scales. In this paper, we investigate population-level human mobility models on a much smaller spatial scale by using them to estimate customer mobility flow between supermarket zones. We use anonymized, ordered customer-basket data to infer empirical mobility flow in supermarkets, and we apply variants of the gravity and intervening-opportunities models to fit this mobility flow and estimate the flow on unseen data. We find that a doubly-constrained gravity model and an extended radiation model (which is a type of intervening-opportunities model) can successfully estimate 65--70\% of the flow inside supermarkets. Using a gravity model as a case study, we then investigate how to reduce congestion in supermarkets using mobility models. We model each supermarket zone as a queue, and we use a gravity model to identify store layouts with low congestion, which we measure either by the maximum number of visits to a zone or by the total mean queue size. We then use a simulated-annealing algorithm to find store layouts with lower congestion than a supermarket's original layout. In these optimized store layouts, we find that popular zones are often in the perimeter of a store. Our research gives insight both into how customers move in supermarkets and into how retailers can arrange stores to reduce congestion. It also provides a case study of human mobility on small spatial scales

    The effect of a local perturbation in a fermionic ladder

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    We study the effect of a local external potential on a system of two parallel spin-polarized nanowires placed close to each other. For single channel nanowires with repulsive interaction we find that transport properties of the system are highly sensitive to the transverse gradient of the perturbation: the asymmetric part completely reflects the electrons leading to vanishing conductance at zero temperature, while the flat potential remains transparent. We envisage a possible application of this unusual property in the sensitive measurement of local potential field gradients.Comment: 4+ pages, 2 figures, typos correcte

    Fluoroquinolone-mediated inhibition of cell growth, S-G2/M cell cycle arrest, and apoptosis in canine osteosarcoma cell lines.

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    Despite significant advancements in osteosarcoma research, the overall survival of canine and human osteosarcoma patients has remained essentially static over the past 2 decades. Post-operative limb-spare infection has been associated with improved survival in both species, yet a mechanism for improved survival has not been clearly established. Given that the majority of canine osteosarcoma patients experiencing post-operative infections were treated with fluoroquinolone antibiotics, we hypothesized that fluoroquinolone antibiotics might directly inhibit the survival and proliferation of canine osteosarcoma cells. Ciprofloxacin or enrofloxacin were found to inhibit p21(WAF1) expression resulting in decreased proliferation and increased S-G(2)/M accumulation. Furthermore, fluoroquinolone exposure induced apoptosis of canine osteosarcoma cells as demonstrated by cleavage of caspase-3 and PARP, and activation of caspase-3/7. These results support further studies examining the potential impact of quinolones on survival and proliferation of osteosarcoma

    GT strengths and electron-capture rates for pf-shell nuclei of relevance for late stellar evolution

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    This paper presents a systematic evaluation of the ability of theoretical models to reproduce experimental Gamow-Teller transition strength distributions measured via (n,p)-type charge-exchange reactions at intermediate beam energies. The focus is on transitions from stable nuclei in the pf shell (45<A<64). The impact of deviations between experimental and theoretical Gamow-Teller strength distributions on derived stellar electron-capture rates at densities and temperatures of relevance for Type Ia and Type II supernovae is investigated. The theoretical models included in the study are based on the shell-model, using the KB3G and GXPF1a interactions, and quasiparticle random-phase approximation (QRPA) using ground-state deformation parameters and masses from the finite-range droplet model.Comment: 25 pages, 27 figure

    Strong correlation effects in single-wall carbon nanotubes

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    We present an overview of strong correlations in single-wall carbon nanotubes, and an introduction to the techniques used to study them theoretically. We concentrate on zigzag nanotubes, although universality dictates that much ofthe theory can also be applied to armchair or chiral nanotubes. We show how interaction effects lead to exotic low energy properties and discuss future directions for studies on correlation effects in nanotubes

    Should Species Distribution Models Account for Spatial Autocorrelation? A Test of Model Projections Across Eight Millennia of Climate Change

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    Aim: The distributions of many organisms are spatially autocorrelated, but it is unclear whether including spatial terms in species distribution models (SDMs) improves projections of species distributions under climate change. We provide one of the first comparative evaluations of the ability of a purely spatial SDM, a purely non-spatial SDM and a SDM that combines spatial and environmental information to project species distributions across eight millennia of climate change. Location: Eastern North America. Methods: To distinguish between the importance of climatic versus spatial explanatory variables we fit three Bayesian SDMs to modern occurrence data for Fagus and Tsuga, two tree genera whose distributions can be reliably inferred from fossil pollen: a spatially varying intercept model, a non-spatial model with climatic variables and a spatially varying intercept plus climate model. Using palaeoclimate data with a high temporal resolution, we hindcasted the SDMs in 1000-year time steps for 8000 years, and compared model projections with palynological data for the same periods. Results: For both genera, spatial SDMs provided better fits to the calibration data, more accurate predictions of a hold-out validation dataset of modern trees and higher variance in current predictions and hindcasted projections than non-spatial SDMs. Performance of non-spatial and spatial SDMs according to the area under the receiver operating curve varied by genus. For both genera, false negative rates between non-spatial and spatial models were similar, but spatial models had lower false positive rates than non-spatial models. Main conclusions: The inclusion of computationally demanding spatial random effects in SDMs may be warranted when ecological or evolutionary processes prevent taxa from shifting their distributions or when the cost of false positives is high.Organismic and Evolutionary Biolog

    Proposal to inform European institutions regarding the regulation of conscientious objection to abortion.

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    The aim of this paper is to define a set of proposals to inform European institutions in the regulation of Conscientious Objection to abortion. The board of the European Society of Contraception and Reproductive Health Care (ESC) was informed on the elements that should in the opinion of the authors be included in a future regulation of Conscientious Objection to abortion in Europe. These elements are outlined in this paper and the debate about them could form the basis for recommendations to the international scientific community and the European institutions. As current measures governing the principle of conscientious objection result in negative consequences regarding women's access to sexual and reproductive health services, they should be changed. Healthcare services should adopt measures to guarantee that a woman's right to voluntary abortion is not limited by the practitioner's stance on the principle of conscientious objection. In the countries where conscientious objection is allowed, the regulation must clearly delineate the extent of the duties and the exemptions of professionals based on the principles of established social consensus. The recommendations included in this document specify measures on the rights of women, the rights and duties of the practitioner, the role of institutions and the role of professional associations
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