284 research outputs found
The Dimer Model for k-phase Organic Superconductors
We prove that the upper electronic bands of k-phase BEDT-TTF salts are
adequately modeled by an half-filled tight-binding lattice with one site per
cell. The band parameters are derived from recent ab-initio calculations,
getting a very simple but extremely accurate one-electron picture. This picture
allows us to solve the BCS gap equation adopting a real-space pairing
potential. Comparison of the calculated superconducting properties with the
experimental data points to isotropic s_0-pairing. Residual many-body or
phonon-mediated interactions offer a plausible explanation of the large variety
of physical properties observed in k-phase BEDT-TTF salts.Comment: 8 pages, 6 PostScript figures, uses RevTe
Option generation in decision making: Ideation beyond memory retrieval.
According to prescriptive decision theories, the generation of options for choice is a central aspect of decision making. A too narrow representation of the problem may indeed limit the opportunity to evaluate promising options. However, despite the theoretical and applied significance of this topic, the cognitive processes underlying option generation are still unclear. In particular, while a cued recall account of option generation emphasizes the role of memory and executive control, other theoretical proposals stress the importance of ideation processes based on various search and thinking processes. Unfortunately, relevant behavioral evidence on the cognitive processes underlying option generation is scattered and inconclusive. In order to reach a better understanding, we carried out an individual-differences study employing a wide array of cognitive predictors, including measures of episodic memory, semantic memory, cognitive control, and ideation fluency. The criterion tasks consisted of three different poorly-structured decision-making scenarios, and the participants were asked to generate options to solve these problems. The main criterion variable of the study was the number of valid options generated, but also the diversity and the quality of generated options were examined. The results showed that option generation fluency and diversity in the context of ill-structured decision making are supported by ideation ability even after taking into account the effects of individual differences in several other aspects of cognitive functioning. Thus, ideation processes, possibly supported by search and thinking processes, seem to contribute to option generation beyond basic associative memory retrieval. The findings of the study also indicate that generating more options may have multifaceted consequences for choice, increasing the quality of the best option generated but decreasing the mean quality of the options in the generated set
Feature-based multi-class classification and novelty detection for fault diagnosis of industrial machinery
Given the strategic role that maintenance assumes in achieving profitability and competitiveness, many industries are dedicating many efforts and resources to improve their maintenance approaches. The concept of the Smart Factory and the possibility of highly connected plants enable the collection of massive data that allow equipment to be monitored continuously and real-time feedback on their health status. The main issue met by industries is the lack of data corresponding to faulty conditions, due to environmental and safety issues that failed machinery might cause, besides the production loss and product quality issues. In this paper, a complete and easy-to-implement procedure for streaming fault diagnosis and novelty detection, using different Machine Learning techniques, is applied to an industrial machinery sub-system. The paper aims to offer useful guidelines to practitioners to choose the best solution for their systems, including a model hyperparameter optimization technique that supports the choice of the best model. Results indicate that the methodology is easy, fast, and accurate. Few training data guarantee a high accuracy and a high generalization ability of the classification models, while the integration of a classifier and an anomaly detector reduces the number of false alarms and the computational time
Symmetrized mean-field description of magnetic instabilities in k-(BEDT-TTF)_2Cu[N(CN)]_2 Y salts
We present a novel and convenient mean-field method, and apply it to study
the metallic/antiferromagnetic interface of k-(BEDT-TTF)_2Cu[N(CN)]_2 Y organic
superconductors (BEDT_TTF is bis-ethylen-dithio-tetrathiafulvalene, Y=Cl, Br).
The method, which fully exploits the crystal symmetry, allows one to obtain the
mean-field solution of the 2D Hubbard model for very large lattices, up to
6x10^5 sites, yielding a reliable description of the phase boundary in a wide
region of the parameter space. The metal/antiferromagnet transtion appears to
be second order, except for a narrow region of the parameter space, where the
transition is very sharp and possibly first order. The cohexistence of metallic
and antiferromagnetic properties is only observed for the transient state in
the case of smooth second order transitions. The relevance of the present
resaults to the complex experimental behavior of centrosymmetric k-phase
BEDT-TTF salts is discussed.Comment: 9 pages in PS format, 7 figures (included in PS), 1 tabl
Stability and test-retest reliability of different hormonal stress markers upon exposure to psychosocial stress at a 4-month interval
The Trier Social Stress Test (TSST) has been shown to reliably induce physiological stress responses in the hypothalamus-pituitary-adrenal (HPA) and in the sympathetic-adrenal-medullary (SAM) axis in cross-sectional studies. However, it was also reported that repeated exposure to the TSST might be associated with habituation, mainly of the HPA axis responsivity. Thus, in all longitudinal stress studies involving repeated TSST administration, potential habituation of the HPA axis response complicates the interpretation of results. The goal
of the present study was therefore to assess stability and test-retest reliability of a number of different endocrinological stress markers as well as subjective stress responses after two exposures to the TSST four months apart. We assessed salivary and plasma cortisol profiles, plasma ACTH and noradrenaline profiles, as well as
subjective stress ratings in healthy volunteers before, during, and after the TSST at six time-points both at testday
1 (TSST_1, n = 42) and test-day 2 (TSST_2, n = 34) 4-months later. Half of the participants received the TSST
in the early, the other half in the late afternoon. Discontinuous growth models were applied to model three
phases of the stress response (preTSST, reactivity, recovery) for each marker. Subsequently, the stability of these
phases was analyzed. Stability and test-retest reliability of standard physiological stress markers such as Areaunder-
the-Curve (AUCG, AUCI), Absolute Peak Change, and Relative Peak Change (RPC) were analyzed as
well. We did not observe strong test-retest effects in any of the endocrinological measures. In contrast, test-retest
effects in subjective stress were characterized by a faster drop directly after the second TSST, whereas the initial
increase before the test period was the same for both test-days. Regarding test-retest-reliability, AUCG was the
most reliable measure across all endocrinological and subjective stress markers (range: r = .606 to .858), while
AUCI and RPC (range: r
Hepatitis B virus-infection related cryoglobulinemic vasculitis. Clinical manifestations and the effect of antiviral therapy: A review of the literature
Objective: Hepatitis B virus (HBV) infection causes chronic hepatitis, cirrhosis, and hepatocellular carcinoma. Furthermore, about 20% of the patients develop extrahepatic manifestations such as cryoglobulinemic vasculitis (CV), polyarteritis nodosa, non-rheumatoid arthritis, glomerulonephritis and non-Hodgkin lymphoma. This review analyzed literature data on clinical manifestations of HBV-related CV and the impact of antiviral therapy with analoques nucleotide. Methods: A PubMed search was performed to select eligible studies in the literature, up to July 2022. Results: Some studies have analyzed clinical manifestations in HBV-related CV and have investigated the role of antiviral therapy with nucleotides analogues (NAs). Clinical manifestations of CV vary from mild to moderate (purpura, asthenia and arthralgias) to severe (leg ulcers, peripheral neuropathy, glomerulonephritis, and non-Hodking lymphoma). NAs therapy leads to suppression of HBV-DNA; therefore, it is capable of producing clinical response in the majority of patients with mild to moderate symptoms. Conclusion: Antiviral therapy with NAs is the first choice for HBV suppression and control of mild to moderate disease. In severe vasculitis (glomerulonephritis, progressive peripheral neuropathy and leg ulcers), rituximab alone or with plasma-exchange is always indicated in combination with antiviral therapy
The largest prehistoric mound in Europe is the Bronze-Age Hill of Udine (Italy) and legend linked its origin to Attila the Hun
Prehistoric monuments often constitute evident landmarks and sometimes, after falling into disuse, fascinated local people enough to stimulate speculations about their origin over time. According to legend, the Hill of Udine (NE Italy) was built by Attila the Hun's soldiers, but its origin (natural or anthropogenic) has been debated until now. Our research analyzed five new 40-m long stratigraphic cores, investigating for the first time the total thickness of the hill and compared the data with the available archaeological information. Moreover, we considered other hills and mounds in northern Italy and other European regions where folklore traditions relate their origin to Attila. The geoarchaeological and ethnographic data prove that the Hill of Udine is a Bronze Age anthropogenic mound erected between 1400 and 1150 BCE and that, later, folklore has transformed the ancestral memory of its origin into legend. By measuring 30 m in height and over 400,000 m(3) in volume, the flat-topped hill is the largest prehistoric mound in Europe. This discovery reveals unprecedented skills in earth construction and confirms significant anthropogenic modifications of the environment during Bronze Age
Densidade de pragas e inimigos naturais em resposta ao tratamento de sementes de soja com inseticidas.
Objetivo: avaliar o efeito do tratamento de sementes de soja com inseticidas químicos sobre a frequência densidade populacional diária acumulada de insetos-praga e artrópodes predadores da parte aérea da soja ao longo do desenvolvimento da cultura
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