272 research outputs found

    Ferromagnetic Quantum Critical Point in CePd2_2P2_2 with Pd \rightarrow Ni Substitution

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    An investigation of the structural, thermodynamic, and electronic transport properties of the isoelectronic chemical substitution series Ce(Pd1x_{1-x}Nix_x)2_2P2_2 is reported, where a possible ferromagnetic quantum critical point is uncovered in the temperature - concentration (TxT-x) phase diagram. This behavior results from the simultaneous contraction of the unit cell volume, which tunes the relative strengths of the Kondo and RKKY interactions, and the introduction of disorder through alloying. Near the critical region at xcrx_{\rm{cr}} \approx 0.7, the rate of contraction of the unit cell volume strengthens, indicating that the cerium ff-valence crosses over from trivalent to a non-integer value. Consistent with this picture, x-ray absorption spectroscopy measurements reveal that while CePd2_2P2_2 has a purely trivalent cerium ff-state, CeNi2_2P2_2 has a small (<< 10 \%) tetravalent contribution. In a broad region around xcrx_{\rm{cr}}, there is a breakdown of Fermi liquid temperature dependences, signaling the influence of quantum critical fluctuations and disorder effects. Measurements of clean CePd2_2P2_2 furthermore show that applied pressure has a similar initial effect to alloying on the ferromagnetic order. From these results, CePd2_2P2_2 emerges as a keystone system to test theories such as the Belitz-Kirkpatrick-Vojta model for ferromagnetic quantum criticality, where distinct behaviors are expected in the dirty and clean limits.Comment: 9 pages, 8 figure

    The spectral, spatial and contrast sensitivity of human polarization pattern perception

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    It is generally believed that humans perceive linear polarized light following its conversion into a luminance signal by diattenuating macular structures. Measures of polarization sensitivity may therefore allow a targeted assessment of macular function. Our aim here was to quantify psychophysical characteristics of human polarization perception using grating and optotype stimuli defined solely by their state of linear polarization. We show: (i) sensitivity to polarization patterns follows the spectral sensitivity of macular pigment; (ii) the change in sensitivity across the central field follows macular pigment density; (iii) polarization patterns are identifiable across a range of contrasts and scales, and can be resolved with an acuity of 15.4 cycles/degree (0.29 logMAR); and (iv) the human eye can discriminate between areas of linear polarization differing in electric field vector orientation by as little as 4.4°. These findings, which support the macular diattenuator model of polarization sensitivity, are unique for vertebrates and approach those of some invertebrates with a well-developed polarization sense. We conclude that this sensory modality extends beyond Haidinger's brushes to the recognition of quantifiable spatial polarization-modulated patterns. Furthermore, the macular origin and sensitivity of human polarization pattern perception makes it potentially suitable for the detection and quantification of macular dysfunction

    Emotional distraction in the context of memory-based orienting of attention

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    Attention can be guided by expectations stemming from long-term memories. In addition to such endogenous cues, exogenous salient stimuli capture attention, such as those conveying threat. This study examined the extent to which threatening distractors affect the employment of memories in guiding attention, and whether this is affected by trait anxiety. Emotional distractors were incorporated into a speeded target detection task, in which memory cues were presented simultaneously with task irrelevant emotional faces. Fearful face distractors disrupted target detection significantly more than neutral faces and the additional disruption to task performance from fearful compared with neutral faces was positively correlated with trait anxiety scores. The current findings of attentional capture by threat in the context of a second, powerful endogenous driver of attention underscore the magnitude of anxiety-related attention to threat. That is, threatening stimuli are sufficiently salient to induce prolonged disruption to goal directed behavior in anxious individuals. (PsycINFO Database Record (c) 2019 APA, all rights reserved)

    Does consultation improve decision-making?

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    This paper reports an experiment designed to test whether prior consultation within a group affects subsequent individual decision-making in tasks where demonstrability of correct solutions is low. In our experiment, subjects considered two paintings created by two different artists and were asked to guess which artist made each painting. We observed answers given by individuals under two treatments: In one, subjects were allowed the opportunity to consult with other participants before making their private decisions; in the other, there was no such opportunity. Our primary findings are that subjects in the first treatment evaluate the opportunity to consult positively, but they perform significantly worse and earn significantly less

    Plasma Gelsolin Depletion and Circulating Actin in Sepsis—A Pilot Study

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    Background: Depletion of the circulating actin-binding protein, plasma gelsolin (pGSN) has been described in septic patients and animals. We hypothesized that the extent of pGSN reduction correlates with outcomes of septic patients and that circulating actin is a manifestation of sepsis. Methodology/Principal Findings: We assayed pGSN in plasma samples from non-surgical septic patients identified from a pre-existing database which prospectively enrolled patients admitted to adult intensive care units at an academic hospital. We identified 21 non-surgical septic patients for the study. Actinemia was detected in 17 of the 21 patients, suggesting actin released into circulation from injured tissues is a manifestation of sepsis. Furthermore, we documented the depletion of pGSN in human clinical sepsis, and that the survivors had significantly higher pGSN levels than the non-survivors (163647 mg/L vs. 89648 mg/L, p = 0.01). pGSN levels were more strongly predictive of 28-day mortality than APACHE III scores. For every quartile reduction in pGSN, the odds of death increased 3.4-fold. Conclusion: We conclude that circulating actin and pGSN deficiency are associated with early sepsis. The degree of pGS

    What are the important components of the clinical assessment of hand problems in older adults in primary care? Results of a Delphi study

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    <p>Abstract</p> <p>Background</p> <p>To identify clinical questions and assessments regarded by health care practitioners as important when assessing undifferentiated hand pain or problems in adults aged 50 years and over presenting to primary care.</p> <p>Methods</p> <p>A purposively selected panel of 26 UK-based Health Care Practitioners comprising occupational therapists, physiotherapists, rheumatologists and general practitioners, were invited to take part in a consensus study involving three postal rounds of a Delphi questionnaire with accompanying case scenarios. Participants were asked to generate questions and assessments (round 1), rate their importance (round 2), and vote on which items were most important (round 3).</p> <p>Results</p> <p>Sixteen Health Care Practitioners agreed to participate with 11 completing all three rounds. The first round of the Delphi study generated 156 questions and 143 assessments. After three rounds agreement was reached on the importance of 25 questions and 19 assessments. Questions were weighted towards current symptoms, but also included the history of previous hand problems, self-reported hand function, co-morbidity and general health. Observation and palpation of features predominated in the choice of assessment, but specific tests, grip strength, evaluation of sensation and hand function were also included.</p> <p>Conclusions</p> <p>A pool of clinical questions and assessments were generated by Health Care Practitioners, and those considered most important for assessing older adults presenting with undifferentiated hand pain and hand problems in primary care were identified. Further evaluation is required to establish the reliability and feasibility of using these questions and assessments in primary care. In particular, the relative contribution of these questions and assessments in evaluating the nature and severity of hand problems, assisting diagnosis, indicating appropriate management, and predicting future course requires further investigation.</p

    Depression and sickness behavior are Janus-faced responses to shared inflammatory pathways

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    It is of considerable translational importance whether depression is a form or a consequence of sickness behavior. Sickness behavior is a behavioral complex induced by infections and immune trauma and mediated by pro-inflammatory cytokines. It is an adaptive response that enhances recovery by conserving energy to combat acute inflammation. There are considerable phenomenological similarities between sickness behavior and depression, for example, behavioral inhibition, anorexia and weight loss, and melancholic (anhedonia), physio-somatic (fatigue, hyperalgesia, malaise), anxiety and neurocognitive symptoms. In clinical depression, however, a transition occurs to sensitization of immuno-inflammatory pathways, progressive damage by oxidative and nitrosative stress to lipids, proteins, and DNA, and autoimmune responses directed against self-epitopes. The latter mechanisms are the substrate of a neuroprogressive process, whereby multiple depressive episodes cause neural tissue damage and consequent functional and cognitive sequelae. Thus, shared immuno-inflammatory pathways underpin the physiology of sickness behavior and the pathophysiology of clinical depression explaining their partially overlapping phenomenology. Inflammation may provoke a Janus-faced response with a good, acute side, generating protective inflammation through sickness behavior and a bad, chronic side, for example, clinical depression, a lifelong disorder with positive feedback loops between (neuro)inflammation and (neuro)degenerative processes following less well defined triggers

    Reduction of Plasma Gelsolin Levels Correlates with Development of Multiple Organ Dysfunction Syndrome and Fatal Outcome in Burn Patients

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    BACKGROUND: Depletion of the circulating actin-binding protein, plasma gelsolin (pGSN) has been described in critically ill surgical patients. We hypothesized that the extent of pGSN reduction might correlate with different outcome of burn patients. The study was performed to evaluate the prognostic implications of pGSN levels on the development of multiple organ dysfunction syndrome (MODS) and fatal outcome in a group of severely burn patients. METHODS AND FINDINGS: 95 patients were included, and they were divided into three groups with different burn area: group I (n = 33), group II (n = 32) and group III (n = 30). According to whether there was development of MODS or not, patients were divided into MODS group (n = 28) and none-MODS group (n = 67); then the patients with MODS were further divided into non-survivor group (n = 17) and survivor group (n = 11). The peripheral blood samples were collected on postburn days (PBD) 1, 3, 7, 14, and 21. The levels of pGSN were determined and T cells were procured from the blood. The contents of cytokines (IL-2, IL-4 and IFN-γ) released by T cells were also measured. The related factors of prognosis were analyzed by using multivariate logistic regression analysis. The results showed that pGSN concentrations, as well as the levels of IL-2 and IFN-γ, decreased markedly on PBD 1-21, whereas, the levels of IL-4 increased markedly in all burn groups as compared with normal controls (P<0.05 or P<0.01), and there were obviously differences between group I and group III (P<0.05 or P<0.01). The similar results were found in MODS patients and the non-survivor group as compared with those without MODS and the survival group on days 3-21 postburn (P<0.05 or P<0.01). Moreover, as the pGSN levels decreased, the incidence of septic complication as well as MODS remarkably increased. CONCLUSIONS: pGSN levels appear to be an early prognostic marker in patients suffering from major burns

    A pilot study using Tissue Velocity Ultrasound Imaging (TVI) to assess muscle activity pattern in patients with chronic trapezius myalgia

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    <p>Abstract</p> <p>Background</p> <p>Different research techniques indicate alterations in muscle tissue and in neuromuscular control of aching muscles in patients with chronic localized pain. Ultrasound can be used for analysis of muscle tissue dynamics in clinical practice.</p> <p>Aim</p> <p>This study introduces a new muscle tissue sensitive ultrasound technique in order to provide a new methodology for providing a description of local muscle changes. This method is applied to investigate trapezius muscle tissue response – especially with respect to specific regional deformation and deformation rates – during concentric shoulder elevation in patients with chronic trapezius myalgia and healthy controls before and after pain provocation.</p> <p>Methods</p> <p>Patients with trapezius myalgia and healthy controls were analyzed using an ultrasound system equipped with tissue velocity imaging (TVI). The patients performed a standardized 3-cm concentric shoulder elevation before and after pain provocation/exercise at a standardized elevation tempo (30 bpm). A standardized region of interest (ROI), an ellipsis with a size that captures the upper and lower fascia of the trapezius muscle (4 cm width) at rest, was placed in the first frame of the loop registration of the elevation. The ROI was re-anchored frame by frame following the same anatomical landmark in the basal fascia during all frames of the concentric phase. In cardiac measurement, tissue velocities are measured in the axial projection towards and against the probe where red colour represents shortening and red lengthening. In the case of measuring the trapezius muscle, tissue deformation measurements are made orthogonally, thus, indirectly. Based on the assumption of muscle volume incompressibility, blue represents tissue contraction and red relaxation. Within the ROI, two variables were calculated as a function of time: <it>deformation </it>and <it>deformation rate</it>. Hereafter, max, mean, and quadratic mean values (RMS) of each variable were calculated and compared before and after pain provocation/exercise.</p> <p>Results</p> <p>This new methodology seems valuable when looking at local muscle changes and studying the mechanism behind chronic muscle pain. The univariate analyses indicate that patients with chronic trapezius myalgia after pain provocation due to exercise at group level showed decreased strain and unchanged strain rate while healthy controls had unchanged strain and increased strain rate. However, the multivariate analysis indicates that most patients showed lower levels according to both strain and strain rate after exercise compared to most controls.</p> <p>Conclusion</p> <p>Tissue velocity imaging can help describe musculoskeletal tissue activity and dynamics in patients with chronic pain conditions. An altered muscle tissue dynamic after pain provocation/exercise among the majority of trapezius myalgia patients compared with the healthy controls was found.</p
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