989 research outputs found

    Phonon relaxation of subgap levels in superconducting quantum point contacts

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    Superconducting quantum point contacts are known to possess two subgap states per each propagating mode. In this note we compute the low-temperature relaxation rate of the upper subgap state into the lower one with the emission of an acoustic phonon. If the reflection in the contact is small, the relaxation time may become much longer than the characteristic lifetime of a bulk quasiparticle.Comment: REVTeX, 4 page

    The potential impact of CT-MRI matching on tumor volume delineation in advanced head and neck cancer

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    To study the potential impact of the combined use of CT and MRI scans on the Gross Tumor Volume (GTV) estimation and interobserver variation. Four observers outlined the GTV in six patients with advanced head and neck cancer on CT, axial MRI, and coronal or sagittal MRI. The MRI scans were subsequently matched to the CT scan. The interobserver and interscan set variation were assessed in three dimensions. The mean CT derived volume was a factor of 1.3 larger than the mean axial MRI volume. The range in volumes was larger for the CT than for the axial MRI volumes in five of the six cases. The ratio of the scan set common (i.e., the volume common to all GTVs) and the scan set encompassing volume (i.e., the smallest volume encompassing all GTVs) was closer to one in MRI (0.3-0.6) than in CT (0.1-0.5). The rest volumes (i.e., the volume defined by one observer as GTV in one data set but not in the other data set) were never zero for CT vs. MRI nor for MRI vs. CT. In two cases the craniocaudal border was poorly recognized on the axial MRI but could be delineated with a good agreement between the observers in the coronal/sagittal MRI. MRI-derived GTVs are smaller and have less interobserver variation than CT-derived GTVs. CT and MRI are complementary in delineating the GTV. A coronal or sagittal MRI adds to a better GTV definition in the craniocaudal directio

    The evolutionary drivers of primate scleral coloration

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    The drivers of divergent scleral morphologies in primates are currently unclear, though white sclerae are often assumed to underlie human hyper-cooperative behaviours. Humans are unusual in possessing depigmented sclerae whereas many other extant primates, including the closely-related chimpanzee, possess dark scleral pigment. Here, we use phylogenetic generalized least squares (PGLS) analyses with previously generated species-level scores of proactive prosociality, social tolerance (both n = 15 primate species), and conspecific lethal aggression (n = 108 primate species) to provide the first quantitative, comparative test of three existing hypotheses. The ‘self-domestication’ and ‘cooperative eye’ explanations predict white sclerae to be associated with cooperative, rather than competitive, environments. The ‘gaze camouflage’ hypothesis predicts that dark scleral pigment functions as gaze direction camouflage in competitive social environments. Notably, the experimental evidence that non-human primates draw social information from conspecific eye movements is unclear, with the latter two hypotheses having recently been challenged. Here, we show that white sclerae in primates are associated with increased cooperative behaviours whereas dark sclerae are associated with reduced cooperative behaviours and increased conspecific lethal violence. These results are consistent with all three hypotheses of scleral evolution, suggesting that primate scleral morphologies evolve in relation to variation in social environment

    Resistively-shunted superconducting quantum point contacts

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    We have studied the Josephson dynamics of resistively-shunted ballistic superconducting quantum point contacts at finite temperatures and arbitrary number of conducting modes. Compared to the classical Josephson dynamics of tunnel junctions, dynamics of quantum point contacts exhibits several new features associated with temporal fluctuations of the Josephson potential caused by fluctuations in the occupation of the current-carrying Andreev levels.Comment: 5 pages, RevTex, 3 postscript figures include

    Cerebellar Gray Matter Volume in Tinnitus

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    Tinnitus is the perception of sound without an external source. The flocculus (FL) and paraflocculus (PFL), which are small lobules of the cerebellum, have recently been implicated in its pathophysiology. In a previous study, the volume of the (P)FL-complex correlated with tinnitus severity in patients that had undergone cerebellopontine angle (CPA) tumor removal. In this study, the relation between tinnitus and gray matter volume (GMV) of the (P)FL-complex, GMV of the other cerebellar lobules and GMV of the cerebellar nuclei is investigated in otherwise healthy participants. Data was processed using the SUIT toolbox, which is dedicated to analysis of imaging data of the human cerebellum. GMV of all cerebellar lobules and nuclei were similar between tinnitus and non-tinnitus participants. Moreover, no relation was present between tinnitus severity, as measured by the Tinnitus Handicap Inventory, and (P)FL-complex GMV, tonsil GMV, or total cerebellar cortical GMV. These results suggest that in otherwise healthy participants, in contrast to participants after CPA tumor removal, no relation between the GMV of neither the (P)FL-complex nor other cerebellar lobules and tinnitus presence and severity exists. These findings indicate that a relation only exists when the (P)FL-complex is damaged, for instance by a CPA tumor. Alternatively, it is possible that differences in (P)FL-complex GMVs are too small to detect with a voxel-based morphometry study. Therefore, the role of the (P)FL-complex in tinnitus remains to be further studied

    Spontaneous brain activity underlying auditory hallucinations in the hearing-impaired

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    Auditory hallucinations, the perception of a sound without a corresponding source, are common in people with hearing impairment. Two forms can be distinguished: simple (i.e., tinnitus) and complex hallucinations (speech and music). Little is known about the precise mechanisms underlying these types of hallucinations. Here we tested the assumption that spontaneous activity in the auditory pathways, following deafferentation, underlies these hallucinations and is related to their phenomenology. By extracting (fractional) Amplitude of Low Frequency Fluctuation [(f)ALFF] scores from resting state fMRI of 18 hearing impaired patients with complex hallucinations (voices or music), 18 hearing impaired patients with simple hallucinations (tinnitus or murmuring), and 20 controls with normal hearing, we investigated differences in spontaneous brain activity between these groups. Spontaneous activity in the anterior and posterior cingulate cortex of hearing-impaired groups was significantly higher than in the controls. The group with complex hallucinations showed elevated activity in the bilateral temporal cortex including Wernicke's area, while spontaneous activity of the group with simple hallucinations was mainly located in the cerebellum. These results suggest a decrease in error monitoring in both hearing-impaired groups. Spontaneous activity of language-related areas only in complex hallucinations suggests that the manifestation of the spontaneous activity represents the phenomenology of the hallucination. The link between cerebellar activity and simple hallucinations, such as tinnitus, is new and may have consequences for treatment. (C) 2020 The Author(s). Published by Elsevier Ltd

    Subharmonic Shapiro steps and assisted tunneling in superconducting point contacts

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    We analyze the current in a superconducting point contact of arbitrary transmission in the presence of a microwave radiation. The interplay between the ac Josephson current and the microwave signal gives rise to Shapiro steps at voltages V = (m/n) \hbar \omega_r/2e, where n,m are integer numbers and \omega_r is the radiation frequency. The subharmonic steps (n different from 1) are a consequence of the ocurrence of multiple Andreev reflections (MAR) and provide an unambiguous signature of the peculiar ac Josephson effect at high transmission. Moreover, the dc current exhibits a rich subgap structure due to photon-assisted MARs.Comment: Revtex, 4 pages, 4 figure

    Health effects of holistic housing renovation in a disadvantaged neighbourhood in the Netherlands:a qualitative exploration among residents and professionals

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    Background: Holistic housing renovations combine physical housing improvements with social and socioeconomic interventions (e.g. referral to social services, debt counselling, involvement in decision-making, promoting social cohesion). In a deprived neighbourhood in Utrecht, the Netherlands, this paper examined residents’ and professionals’ experiences, ideas, and perceptions regarding holistic housing renovation, its health effects, and underlying mechanisms explaining those effects. Methods: Semi-structured in-depth interviews were conducted with 21 social housing residents exposed to holistic housing renovation, and 12 professionals involved in either the physical renovation or social interventions implemented. Residents were interviewed in various renovation stages (before, during, after renovation). Transcripts were deductively and inductively coded using qualitative software. Results: Residents experienced and professionals acknowledged renovation stress caused by nuisance from construction work (noise, dust), having to move stuff around, and temporary moving; lack of information and control; and perceived violation of privacy. Involvement in design choices was appreciated, and mental health improvement was expected on the long term due to improved housing quality and visual amenity benefits. Social contact between residents increased as the renovation became topic for small talk. Few comments were made regarding physical health effects. The interviews revealed a certain amount of distrust in and dissatisfaction with the housing corporation, construction company, and other authorities. Conclusions: Renovation stress, aggravated by lack of information and poor accessibility of housing corporation and construction company, negatively affects mental health and sense of control. Potential stress relievers are practical help with packing and moving furniture, and increased predictability by good and targeted communication. Social interventions can best be offered after renovation, when residents live in their renovated apartment and the nuisance and stress from the renovation is behind them. Social partners can use the period leading up to the renovation to show their faces, offer practical help to reduce renovation stress, and increase residents’ trust in their organization and authorities in general. This might also contribute to residents’ willingness to accept help with problems in the social domain after renovation.</p

    Long-term Anatomical and Functional Results of Robot-Assisted Pelvic Floor Surgery for the Management of Multicompartment Prolapse:A Prospective Study

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    BACKGROUND: Long-term data on robot-assisted sacrocolporectopexy for the treatment of multicompartment pelvic organ prolapse are scarce. With the rising prevalence of prolapse and increasing surgical repair, it is essential to evaluate long-term results. OBJECTIVE: This study aimed to evaluate long-term functional and anatomic outcomes after sacrocolporectopexy. DESIGN: This is a prospective, observational cohort study. SETTINGS: This study was conducted at a teaching hospital with tertiary referral function for patients with gynecological/rectal prolapse. PATIENTS: All patients undergoing robot-assisted sacrocolporectopexy from 2011 to 2012 were included. INTERVENTION: Robot-assisted sacrocolporectopexy was performed. MAIN OUTCOME MEASURES: The primary outcome was the anatomic cure rate after 1 and 4 years, defined as simplified pelvic organ prolapse quantification stage 1 vaginal apical prolapse and no external rectal prolapse or internal rectal prolapse present. Kaplan-Meier curves were used for determination of recurrence-free intervals. Secondary outcomes were functional pelvic floor symptoms (symptoms of bulge, obstructed defecation, fecal incontinence, urogenital distress inventory) and quality of life (Pelvic Floor Impact Questionnaire). RESULTS: Fifty-three patients were included. After 12 and 48 months, the recurrence-free intervals based on Kaplan-Meier estimates were 100% and 90%. In total, there were 10 recurrences: 2 apical and 8 internal rectal prolapses. Symptoms of bulge (94%-12%; p < 0.0005), fecal incontinence (62%-32%; p < 0.0005), obstructed defecation (59%-24%; p = 0.008), and median Pelvic Floor Impact Questionnaire scores (124-5; p = 0.022) improved significantly at final follow-up. Median urogenital distress inventory scores showed improvement after 1 year (30-13; p = 0.021). LIMITATIONS: This was an observational, single-center study with selective postoperative imaging. CONCLUSIONS: Ninety percent of patients were recurrence free 48 months after robot-assisted sacrocolporectopexy. Symptoms of vaginal bulge, quality of life, constipation, and fecal incontinence improved significantly. However, a subgroup of patients showed persistent bowel complaints that underlie the complexity of multicompartment prolapse. See Video Abstract at http://links.lww.com/DCR/B265
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