3,115 research outputs found
Dimerisation of Fe bisdithiolene complexes; An electrochemical study
ArticleAn electrochemical study of the dimerisation of the [Fe(qdt)2]22− and [Fe(mnt)2]22− iron complexes in dichloromethane, dimethylformamide and acetonitrile, by cyclic voltammetry and ionic conductivity is reported. Ionic conductivity measurements indicate an increased dissociation of the dimers in dimethylformamide and acetonitrile compared to dichloromethane. In [Fe(mnt)2] in dichloromethane, only dimer oxidation processes are observed in cyclic voltammetry, while in [Fe(qdt)2] both dimeric and monomeric species are involved in redox processes. In acetonitrile and DMF the observed processes correspond to the dissociated monomeric species only. This study demonstrates the major role of the nature of the solvent in the monomer/dimer equilibrium in solution, which appears more easily shifted towards dissociation in the complex with qdt ligands than with mnt and is favoured by N- and O-containing solvents.This work was partially supported FCT (Portugal) through contracts PTDC/QUI/101788/2008 and PTDC/QEQ-SUP/1413/2012
Model specification and the reliability of fMRI results: Implications for longitudinal neuroimaging studies in psychiatry
Functional Magnetic Resonance Imagine (fMRI) is an important assessment tool in longitudinal studies of mental illness and its treatment. Understanding the psychometric properties of fMRI-based metrics, and the factors that influence them, will be critical for properly interpreting the results of these efforts. The current study examined whether the choice among alternative model specifications affects estimates of test-retest reliability in key emotion processing regions across a 6-month interval. Subjects (N = 46) performed an emotional-faces paradigm during fMRI in which neutral faces dynamically morphed into one of four emotional faces. Median voxelwise intraclass correlation coefficients (mvICCs) were calculated to examine stability over time in regions showing task-related activity as well as in bilateral amygdala. Four modeling choices were evaluated: a default model that used the canonical hemodynamic response function (HRF), a flexible HRF model that included additional basis functions, a modified CompCor (mCompCor) model that added corrections for physiological noise in the global signal, and a final model that combined the flexible HRF and mCompCor models. Model residuals were examined to determine the degree to which each pipeline met modeling assumptions. Results indicated that the choice of modeling approaches impacts both the degree to which model assumptions are met and estimates of test-retest reliability. ICC estimates in the visual cortex increased from poor (mvICC = 0.31) in the default pipeline to fair (mvICC = 0.45) in the full alternative pipeline - an increase of 45%. In nearly all tests, the models with the fewest assumption violations generated the highest ICC estimates. Implications for longitudinal treatment studies that utilize fMRI are discussed. © 2014 Fournier et al
Factor V Leiden and Prothrombin G20210A in Portuguese Women with Recurrent Miscarriage: Is it Worthwhile to Investigate?
OBJECTIVE: To compare the prevalence of factor V Leiden (FVL) and prothrombin (PT) G20210A mutations in Portuguese women with unexplained recurrent miscarriage (RM) and a control group of parous women.
MATERIALS AND METHODS: FVL and PT G20210A analysis were carried out in 100 women with three or more consecutive miscarriages and 100 controls with no history of pregnancy losses. Secondary analysis was made regarding gestational age at miscarriage (embryonic and fetal losses).
RESULTS: Overall, the prevalence of FVL and PT G20210A was similar in women with RM (5 and 3%) compared with controls (5 and 1%) OR 1.36 (CI 95% 0.45-4.08). In RM embryonic subgroup, PT G20210A was observed in 1.3% of women and FVL prevalence (2.6%) was inclusively lesser than that of controls. Both polymorphisms were more prevalent in women with fetal losses than in controls, although statistical significance was not reached due to the small size of the >10 weeks' subgroup.
CONCLUSION: These data indicate that neither FVL nor PT G20210A is associated with RM prior to 10 weeks of gestation. Therefore, its screening is not indicated as an initial approach in Portuguese women with embryonic RM and negative personal thromboembolic history
Quantum networks reveal quantum nonlocality
The results of local measurements on some composite quantum systems cannot be
reproduced classically. This impossibility, known as quantum nonlocality,
represents a milestone in the foundations of quantum theory. Quantum
nonlocality is also a valuable resource for information processing tasks, e.g.
quantum communication, quantum key distribution, quantum state estimation, or
randomness extraction. Still, deciding if a quantum state is nonlocal remains a
challenging problem. Here we introduce a novel approach to this question: we
study the nonlocal properties of quantum states when distributed and measured
in networks. Using our framework, we show how any one-way entanglement
distillable state leads to nonlocal correlations. Then, we prove that
nonlocality is a non-additive resource, which can be activated. There exist
states, local at the single-copy level, that become nonlocal when taking
several copies of it. Our results imply that the nonlocality of quantum states
strongly depends on the measurement context.Comment: 4 + 3 pages, 4 figure
Social norms information for alcohol misuse in university and college students
Drinking is influenced by youth perceptions of how their peers drink. These perceptions are often incorrect, overestimating peer drinking norms. If inaccurate perceptions can be corrected, young people may drink less.info:eu-repo/semantics/publishedVersio
Delays in access to care for abortion-related complications: the experience of women in Northeast Brazil.
Around 18 million unsafe abortions occur in low and middle-income countries and are associated with numerous adverse consequences to women's health. The time taken by women with complications to reach facilities where they can receive appropriate post-abortion care can influence the risk of death and the extent of further complications. All women aged 18+ admitted for abortion complications to public-sector hospitals in three capital cities in the Northeastern Brazil between August-December 2010 were interviewed; medical records were extracted (N = 2,804). Nearly all women (94%) went straight to a health facility, mainly to a hospital (76.6%); the rest had various care-seeking paths, with a quarter visiting 3+ hospitals. Women waited 10 hours on average before deciding to seek care. 29% reported difficulties in starting to seek care, including facing challenges in organizing childcare, a companion or transport (17%) and fear/stigma (11%); a few did not initially recognize they needed care (0.4%). The median time taken to arrive at the ultimate facility was 36 hours. Over a quarter of women reported experiencing difficulties being admitted to a hospital, including long waits (15%), only being attended after pregnant women (8.9%) and waiting for a bed (7.4%). Almost all women (90%) arrived in good condition, but those with longer delays were more likely to have (mild or severe) complications. In Brazil, where access to induced abortion is restricted, women face numerous difficulties receiving post-abortion care, which contribute to delay and influence the severity of post-abortion complications
Do critical thinkers drink too much alcohol, forget to do class assignments, or cheat on exams? Using a critical thinking measure to predict college students’ real-world outcomes
Critical thinking is a higher-order way of reasoning composed of the skill and will to use cognitive abilities and knowledge on a daily basis. It is identified as essential by higher education institutions, corporations, and society in general. To analyze whether college students are critical thinkers in their daily lives, the Halpern Critical Thinking Assessment (HCTA; Halpern in Halpern Critical Thinking Assessment (Measurement instrument), Schuhfried, Mödling, 2012) and the real-world outcomes inventory (RWO; Butler in Appl Cogn Psychol 26(5):721–729, 2012) were administered to 238 students. We performed a cluster analysis (K-means-constrained clustering method), and ANOVAs for each cluster solution tested to identify the most suitable clustering solution, taking the RWO inventory dimensions as dependent variables and cluster membership as an independent variable. Four separate clusters emerged, each representing a different profile related to students’ everyday negative outcomes resulting from a lack of critical thinking. We performed multinomial logistic regression to examine which dimensions of the HCTA test, as well as gender, age, and disciplinary area, predicted the four singular groups of students that emerged: “Mature,” “Risk-taking,” “Lost in translation,” and “Reflective.” Results indicate that: (1) age is a relevant predictor of slackness, rashness, and health neglect, all characteristics of “Mature” students; (2) students who are particularly skilled in hypothesis testing tend to be “Risk-taking,” while it is less likely that students who are specifically competent in argument analysis will be in this group; (3) gender is relevant to predict “Lost in translation” students, while argument analysis is negatively related to the chances of being in this group. Our study supports the relevance of critical thinking in daily decisions and everyday outcomes.FCT -Fundação para a Ciência e a Tecnologia(Advanced Training)info:eu-repo/semantics/publishedVersio
Severe hereditary spherocytosis and distal renal tubular acidosis associated with the total absence of band 3
Absence of band 3, associated with the mutation Coimbra (V488M) in the homozygous state, caused severe hereditary spherocytosis in a young child. Although prenatal testing was made available to the parents, it was declined. Because the fetus stopped moving near term, an emergency cesarean section was performed and a severely anemic, hydropic female baby was delivered. She was resuscitated and initially kept alive with respiratory assistance and hypertransfusion therapy. Cord blood smears revealed erythroblastosis, poikilocytosis, and red cells with stalk-like elongations. Band 3 and protein 4.2 were absent; spectrin, ankyrin, and glycophorin A were significantly reduced. Renal tubular acidosis was detected by the age of 3 months. Nephrocalcinosis appeared soon thereafter. After 3 years of follow-up the child is doing reasonably well on a regimen that includes regular blood transfusions and daily bicarbonate supplements. The long-term prognosis remains uncertain given the potential for hematologic and renal complications
Fungal iron availability during deep seated candidiasis is defined by a complex interplay involving systemic and local events
Peer reviewedPublisher PD
RG-improved single-particle inclusive cross sections and forward-backward asymmetry in production at hadron colliders
We use techniques from soft-collinear effective theory (SCET) to derive
renormalization-group improved predictions for single-particle inclusive (1PI)
observables in top-quark pair production at hadron colliders. In particular, we
study the top-quark transverse-momentum and rapidity distributions, the
forward-backward asymmetry at the Tevatron, and the total cross section at
NLO+NNLL order in resummed perturbation theory and at approximate NNLO in fixed
order. We also perform a detailed analysis of power corrections to the leading
terms in the threshold expansion of the partonic hard-scattering kernels. We
conclude that, although the threshold expansion in 1PI kinematics is
susceptible to numerically significant power corrections, its predictions for
the total cross section are in good agreement with those obtained by
integrating the top-pair invariant-mass distribution in pair invariant-mass
kinematics, as long as a certain set of subleading terms appearing naturally
within the SCET formalism is included.Comment: 55 pages, 14 figures, 6 table
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