5,644 research outputs found

    Photoemission Spectra from Reduced Density Matrices: the Band Gap in Strongly Correlated Systems

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    We present a method for the calculation of photoemission spectra in terms of reduced density matrices. We start from the spectral representation of the one-body Green's function G, whose imaginary part is related to photoemission spectra, and we introduce a frequency-dependent effective energy that accounts for all the poles of G. Simple approximations to this effective energy give accurate spectra in model systems in the weak as well as strong correlation regime. In real systems reduced density matrices can be obtained from reduced density-matrix functional theory. Here we use this approach to calculate the photoemission spectrum of bulk NiO: our method yields a qualitatively correct picture both in the antiferromagnetic and paramagnetic phases, contrary to mean-field methods, in which the paramagnet is a metal

    E-ABR in patients with cochlear implant: A comparison between patients with malformed cochlea and normal cochlea

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    OBJECTIVES: This study aims to compare the electrical auditory brainstem response (EABR) following cochlear implant (CI) surgery in pediatric subjects with cochlear malformation and a normal cochlea, in order to assess the sensitivity of EABR and to evaluate the surgery outcome. MATERIALS and METHODS: A total of 26 pediatric subjects who were deaf and scheduled for CI surgery were enrolled into this case control study. Group A (n=20) included subjects with a normo-conformed cochlea. Group B (n=6) included subjects with cochlear malformation. Subjects were evaluated with EABR immediately (T0) and 6 months (T1) post-CI surgery. The EABR Waves III and V average amplitude and latency were compared across time, separately for each group, and across groups, separately for each time. RESULTS: Auditory brainstem response (ABR) could only be recorded in Group A. We were able to record EABR from all subjects at T0 and T1, and waves III and V were present in all the recorded signals. There were no statistically significant differences between T0 and T1 in EABR Waves III and V in terms of average amplitude and latency in neither group. When comparing Groups A and B, the only statistically significant difference was the average amplitude of wave V, both at T0 and T1. CONCLUSION: EABR is a valid tool to measure the auditory nerve integrity after CI surgery in patients with a normal and malformed cochlea, as shown by its ability to measure waves III and V when ABR is absent. The EABR testing should be performed before and after CI surgery, and EABR should be used as a measure of outcome, especially in patients with a malformed cochlea

    Kaon physics with the KLOE detector

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    In this paper we discuss the recent finalized analyses by the KLOE experiment at DAΦ\PhiNE: the CPT and Lorentz invariance test with entangled K0Kˉ0K^0 \bar{K}^0 pairs, and the precision measurement of the branching fraction of the decay K+→π+π−π+(γ){ K^+} \rightarrow \pi^+\pi^-\pi^+(\gamma). We also present the status of an ongoing analysis aiming to precisely measure the K±K^{\pm} mass

    Improving Multi-Objective Test Case Selection by Injecting Diversity in Genetic Algorithms

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    A way to reduce the cost of regression testing consists of selecting or prioritizing subsets of test cases from a test suite according to some criteria. Besides greedy algorithms, cost cognizant additional greedy algorithms, multi-objective optimization algorithms, and Multi-Objective Genetic Algorithms (MOGAs), have also been proposed to tackle this problem. However, previous studies have shown that there is no clear winner between greedy and MOGAs, and that their combination does not necessarily produce better results. In this paper we show that the optimality of MOGAs can be significantly improved by diversifying the solutions (sub-sets of the test suite) generated during the search process. Specifically, we introduce a new MOGA, coined as DIV-GA (DIversity based Genetic Algorithm), based on the mechanisms of orthogonal design and orthogonal evolution that increase diversity by injecting new orthogonal individuals during the search process. Results of an empirical study conducted on eleven programs show that DIV-GA outperforms both greedy algorithms and the traditional MOGAs from the optimality point of view. Moreover, the solutions (sub-sets of the test suite) provided by DIV-GA are able to detect more faults than the other algorithms, while keeping the same test execution cost

    Optical coherence tomography in Alzheimer's disease. A meta-analysis

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    BACKGROUND: Alzheimer's disease (AD) is a neurodegenerative disorder, which is likely to start as mild cognitive impairment (MCI) several years before the its full-blown clinical manifestation. Optical coherence tomography (OCT) has been used to detect a loss in peripapillary retina nerve fiber layer (RNFL) and a reduction in macular thickness and volume of people affected by MCI or AD. Here, we performed an aggregate meta-analysis combining results from different studies. METHODS AND FINDINGS: Data sources were case-control studies published between January 2001 and August 2014 (identified through PubMed and Google Scholar databases) that examined the RNFL thickness by means of OCT in AD and MCI patients compared with cognitively healthy controls. RESULTS: 11 studies were identified, including 380 patients with AD, 68 with MCI and 293 healthy controls (HC). The studies suggest that the mean RNFL thickness is reduced in MCI (weighted mean differences in μm, WMD = -13.39, 95% CI: -17.34 to -9.45, p = 0.031) and, even more so, in AD (WMD = -15.95, 95% CI: -21.65 to -10.21, p<0.0001) patients compared to HC. RNFL in the 4 quadrants were all significantly thinner in AD superior (superior WMD = -24.0, 95% CI: -34.9 to -13.1, p<0.0001; inferior WMD = -20.8, 95% CI: -32.0 to -9.7, p<0.0001; nasal WMD = -14.7, 95% CI: -23.9 to -5.5, p<0.0001; and temporal WMD = -10.7, 95% CI: -19.9 to -1.4, p<0.0001); the same significant reduction in quadrant RNFL was observed in MCI patients compared with HC (Inferior WMD = -20.22, 95% CI: -30.41 to -10.03, p = 0.0001; nasal WMD = -7.4, 95% CI: -10.08 to -4.7, p = 0.0000; and temporal WMD = -6.88, 95% CI: -12.62 to -1.13, p = 0.01), with the exception of superior quadrant (WMD = -19.45, 95% CI: -40.23 to 1.32, p = 0.06). CONCLUSION: Results from the meta-analysis support the important role of OCT for RNFL analysis in monitoring the progression of AD and in assessing the effectiveness of purported AD treatments

    Comparison of cheeses from goats fed 7 forages based on a new health index.

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    This study proposed the General Health Index of Cheese (GHIC) as an indicator for the presence of health-promoting compounds in cheese and compared the antioxidant capacity and phenolic and fatty acid contents of cheeses from goats consuming 7 forage species. Ninety-one homogeneous Red Syrian goats were randomly assigned to 1 of 7 feeding treatments (Festuca arundinacea, Hordeum vulgare, Triticosecale, Pisum sativum, Trifolium alexandrinum, Vicia sativa, and Vicia faba minor). The housed goat groups received the scheduled forage ad libitum. Forage species affected the antioxidant capacity, the phenolic and fatty acid contents, the Health Promoting Index, and the GHIC. Trifolium alexandrinum, Triticosecale, and Hordeum vulgare showed a clear advantage in terms of beneficial fatty acids content in goat cheese. Cheese from the Triticosecale group also showed a high antioxidant capacity value even if its polyphenol content was intermediate compared with others. Trifolium alexandrinum and Triticosecale had the highest value of the new index GHIC. This comparison suggests that there are important differences in fatty acid profile and polyphenol content among cheeses from goats fed grasses and legumes commonly used in the Mediterranean area. In this first approach, GHIC index, which combines the positive components found in cheese, seems to be a useful tool to provide an indication concerning the general health value of the product

    Validation of the Italian version of the Burn Specific Health Scale-Brief

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    Introduction A growing awareness of psychological and functional impairment due to burns have led to the development of specific instruments to evaluate Quality of Life in this population, such as the Burn Specific Health Scale - Brief (BSHS-B), whose psychometric properties have been consistently verified. The aim of this study was to translate the BSHS-B into Italian and to investigate its reliability and validity. Methods Translation procedures were carried out according to accepted standards. Internal reliability was assessed using Cronbach's alpha coefficient. Concurrent validity was evaluated through correlations between the BSHS-B and the Short-Form 36 Health Survey (SF-36), the Self-report Clinical Inventory (SCL-90), and the Body Uneasiness Test (BUT). Results The overall Cronbach's alpha value for the scale was 0.887. Significant correlations were found between the Italian BSHS-B domains, the SF-36 subscales (Spearman's rho: 0.184-0.414), and several SCL-90 subscales (Spearman's rho: -0.173 to -0.477). Furthermore, the affect and relationship domain and the skin domain of the BSHS-B negatively correlated with the compulsive self-monitoring and depersonalization subscales of the BUT. Conclusion The Italian translation of BSHS-B has shown satisfactory internal consistency, criterion validity, and convergent validity, supporting its application in routine clinical practice as well as in international studies. © 2013 Elsevier Ltd and ISBI

    Luminescent Oil-Soluble Carbon Dots toward White Light Emission: A Spectroscopic Study

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    Carbon dots (C-dots) are emerging as new emitting nanomaterials for optoelectronics, bioimaging, and biosensing thanks to their high quantum yield (QY), biocompatibility, low toxicity, and cost-effective sources. Although the origin of their photoluminescence (PL) mechanism (i.e., their strong blue-green emission and excitation dependent fluorescence) is still controversial, it has been demonstrated to depend on the synthetic protocols and experimental conditions, able to modify the surface properties. Here oil-dispersible C-dots, synthesized by carbonization of citric acid in the presence of hexadecylamine in high boiling organic solvent, are thoroughly investigated by systematically controlling the synthetic reaction parameters. Similarly to what was found for water-soluble C-dots, citric acid in the presence of amine-containing passivating agents improves the PL emission of C-dots via the formation of molecular fluorescent derivatives alongside the carbonization process. We demonstrate that at growth temperature of 200 °C such C-dots exhibit an interesting and intense white emission, when excited in the blue region, thus resulting in a biocompatible colloidal white emitting single nano-objects. The incorporation of the nanoparticles in a poly(methyl methacrylate) (PMMA) host matrix, to obtain free-standing nanocomposite films, is demonstrated not to affect the color point, which still falls in the white color region of the 1931 CIE diagram. Remarkably, the emission properties are retained even after several months of films exposure to air and sunlight, thus confirming the color stability of the nanoparticles against aging

    Analysis of the impact of COVID-19 pandemic on functional gastrointestinal disorders among paediatric population

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    Functional gastrointestinal disorders are common gastrointestinal diseases. The pathophysiology is multifactorial and psychosocial distress worsens symptoms severity. Since the end of 2019 the world has been facing COVID-19 pandemic. The associated control measures have affected the psychological health of people. The aim of the present study is to evaluate the impact of the COVID-19 pandemic on the prevalence of functional gastrointestinal disorders among Italian children and adolescents
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