670 research outputs found
Single mode terahertz quantum cascade amplifier
A terahertz (THz) optical amplifier based on a 2.9 THz quantum cascade laser (QCL) structure has been demonstrated. By depositing an antireflective coating on the QCL facet, the laser mirror losses are enhanced to fully suppress the lasing action, creating a THz quantum cascade (QC) amplifier. Terahertz radiation amplification has been obtained, by coupling a separate multi-mode THz QCL of the same active region design to the QC amplifier. A bare cavity gain is achieved and shows excellent agreement with the lasing spectrum from the original QCL without the antireflective coating. Furthermore, a maximum optical gain of âŒ30âdB with single-mode radiation output is demonstrated
Single mode terahertz quantum cascade amplifier
A terahertz (THz) optical amplifier based on a 2.9 THz quantum cascade laser (QCL) structure has been demonstrated. By depositing an antireflective coating on the QCL facet, the laser mirror losses are enhanced to fully suppress the lasing action, creating a THz quantum cascade (QC) amplifier. Terahertz radiation amplification has been obtained, by coupling a separate multi-mode THz QCL of the same active region design to the QC amplifier. A bare cavity gain is achieved and shows excellent agreement with the lasing spectrum from the original QCL without the antireflective coating. Furthermore, a maximum optical gain of âŒ30âdB with single-mode radiation output is demonstrated
Bowel and Bladder-Control Anxiety: A Preliminary Description of a Viscerally-Centred Phobic Syndrome
Background: People with anxiety disorders occasionally report fears about losing control of basic bodily functions in public. These anxieties often occur in the absence of physical disorder and have previously been recognized as âobsessiveâ anxieties reflecting a preoccupation with loss of bowel/bladder control. Motivated by our observations of the non-trivial occurrence of such anxieties in our clinical practice we sought to fill a gap in the current understanding of âbowel/bladder-control anxietiesâ. Method: Eligible participants completed an internet survey. Results: Bowel/bladder-control anxieties (n=140) tended to emerge in the mid to late 20s and were associated with high levels of avoidance and functional impairment. There was a high prevalence of panic attacks (78%); these were especially prevalent among those with bowel-control anxiety. Of those with panic attacks, 62% indicated that their main concern was being incontinent during a panic attack. Significantly, a proportion of respondents (~16%) reported actually being incontinent during a panic attack. Seventy percent of participants reported intrusive imagery related to loss of bowel/bladder control. Intrusion-related distress was correlated with agoraphobic avoidance and general role impairment. Some differences were noted between those with predominantly bowel-, predominantly bladder- and those with both bowel and bladder-control anxieties. Conclusion: This preliminary characterization indicates that even in a non-treatment seeking community sample, bowel/bladder-control anxieties are associated with high levels of distress and impairment. Further careful characterization of these anxieties will clarify their phenomenology and help us develop or modify treatment protocols in a way that takes account of any special characteristics of such viscerally-centred phobic syndromes
Pathogenicity locus, core genome, and accessory gene contributions to Clostridium difficile virulence
Clostridium difficile is a spore-forming anaerobic bacterium that causes colitis in patients with disrupted colonic microbiota. While some individuals are asymptomatic C. difficile carriers, symptomatic disease ranges from mild diarrhea to potentially lethal toxic megacolon. The wide disease spectrum has been attributed to the infected hostâs age, underlying diseases, immune status, and microbiome composition. However, strain-specific differences in C. difficile virulence have also been implicated in determining colitis severity. Because patients infected with C. difficile are unique in terms of medical history, microbiome composition, and immune competence, determining the relative contribution of C. difficile virulence to disease severity has been challenging, and conclusions regarding the virulence of specific strains have been inconsistent. To address this, we used a mouse model to test 33 clinical C. difficile strains isolated from patients with disease severities ranging from asymptomatic carriage to severe colitis, and we determined their relative in vivo virulence in genetically identical, antibiotic-pretreated mice. We found that murine infections with C. difficile clade 2 strains (including multilocus sequence type 1/ribotype 027) were associated with higher lethality and that C. difficile strains associated with greater human disease severity caused more severe disease in mice. While toxin production was not strongly correlated with in vivo colonic pathology, the ability of C. difficile strains to grow in the presence of secondary bile acids was associated with greater disease severity. Whole-genome sequencing and identification of core and accessory genes identified a subset of accessory genes that distinguish high-virulence from lower-virulence C. difficile strains
Identification of heterotic cross combinations for various agromorphological and some quality traits in bread wheat (Triticum aestivum L.)
A study was conducted to identify the best heterotic cross for various agromorphological and some quality traits involving 10 parents and their 45 F1s excluding reciprocals during 2012-13 and 2013-14. The higher magnitude of heterosis for all the agromorphological and quality traits was not expressed in a single cross combination. It varied from cross to cross due to diverse genetic background of their parents. The highest heterobeltiosis (35.68%, 11.11%, 11.44%), average heterosis (38.97%, 9.13%, 10.26%) and standard heterosis (31.09%, 7.84%, 10.41%) for grain yield, spikelets per spike and grains per spike respectively, was showed by HD 3095 x RAJ 4246 and this cross also showed highly significant (at <1% level of significant) heterosis for biological yield, flag leaf area, spike length and productive tillers. Whereas PBW 435 x RAJ 4246 were common for gluten content (8.52% and 7.72%), grain yield (33.11% and 33.64%), productive tillers (16.15% and 13.53%) and biological yield (36.27% and 21.98%) which showed superior average heterosis and heterobeltiosis respectively, therefore, these crosses may be exploit-ed in a national hybrid wheat breeding programme may offer genetic improvement in breeding for higher grain yield, agromorphological and quality traits in bread wheat. The presence of high heterosis for yield contributing compo-nents is not only for developing hybrids through exploitation of heterosis but also helps to produce transgressive segregants for developing of superior homozygous lines
The COVID-19 Wellbeing Study: Examining perceived coercion and psychological wellbeing during the COVID-19 pandemic by means of an online survey, asynchronous virtual focus groups and individual interviews â a protocol
Introduction: The COVID-19 pandemic has resulted in
many countries applying restrictive measures, such as
lockdown, to contain and prevent further spread. The
psychological impact of lockdown and working as a
healthcare worker on the frontline has been chronicled
in studies pertaining to previous infectious disease
pandemics that have reported the presence of depressive
symptoms, anxiety, insomnia, and post-traumatic stress
symptoms. Potentially linked to psychological well-being
and not yet studied is the possibility that lockdown and
working on the frontline of the pandemic are associated
with perceptions of coercion.
Methods and analysis: The present study aimed
to examine perceived coercion in those who have
experienced COVID-19-related lockdown and/or worked
as a frontline healthcare worker across three European
countries. It aimed to describe how such perceptions may
impact on psychological well-being, coping and posttraumatic growth. It will employ an explanatory mixedmethods research methodology consisting of an online
survey and online asynchronous virtual focus groups
(AVFGs) and individual interviews. Ï2
tests and analyses
of variance will be used to examine whether participants
from different countries differ according to demographic
factors, whether there are differences between cohorts on
perceived coercion, depression, anxiety and post-traumatic
growth scores. The relationship between coercion and
symptoms of distress will be assessed using multiple
regression. Both the AVFGs and the narrative interviews
will be analysed using thematic narrative analysis.
Ethics and dissemination: The study has been approved
by University College Londonâs Research Ethics Committee
under Project ID Number 7335/004. Results will be
disseminated by means of peer-reviewed publications and
at national and/or international conferences
Processing of alcohol-related health threat in at-risk drinkers: an online study of gender-related self-affirmation effects
Aims: Defensiveness in response to threatening health information related to excessive alcohol consumption prevents appropriate behaviour change. Alternatively, self-affirmation may improve cognitive-affective processing of threatening information, thus contributing to successful self-regulation.
Methods: Effects of an online self-affirmation procedure were examined in at-risk university student drinkers. Participants were randomly assigned to a self-affirmation (writing about personally relevant values) or control task (writing about values relevant to another person) prior to presentation of alcohol-related threatening information. Assessment of prosocial feelings (e.g. âloveâ) after the task served as a manipulation check. Generic and personalized information regarding the link between alcohol use and cancer was presented, followed by assessment of perceived threat, message avoidance and derogation. Page dwell-times served as indirect indices of message engagement. Alcohol consumption and intention to drink less were assessed during the first online session and at 1-week and 1-month follow-up.
Results: Although self-affirmation resulted in higher levels of prosocial feelings immediately after the task, there was no effect on behaviour in the self-affirmation group. Effects on intention were moderated by gender, such that men showed lower intention immediately after self-affirmation, but this increased at 1-week follow-up. Women's intention to reduce consumption in the self-affirmation group reduced over time. Trend-level effects on indices of derogation and message acceptance were in the predicted direction only in men.
Conclusion: It is feasible to perform self-affirmation procedures in an online environment with at-risk drinkers. However, use of internet-based procedures with this population may give rise to (gender-dependent) effects that are substantially diluted compared with lab-based experiments
The expert's knowledge combined with AI outperforms AI alone in seizure onset zone localization using resting state fMRI
We evaluated whether integration of expert guidance on seizure onset zone (SOZ) identification from resting state functional MRI (rs-fMRI) connectomics combined with deep learning (DL) techniques enhances the SOZ delineation in patients with refractory epilepsy (RE), compared to utilizing DL alone. Rs-fMRI was collected from 52 children with RE who had subsequently undergone ic-EEG and then, if indicated, surgery for seizure control (n = 25). The resting state functional connectomics data were previously independently classified by two expert epileptologists, as indicative of measurement noise, typical resting state network connectivity, or SOZ. An expert knowledge integrated deep network was trained on functional connectomics data to identify SOZ. Expert knowledge integrated with DL showed a SOZ localization accuracy of 84.8 ± 4.5% and F1 score, harmonic mean of positive predictive value and sensitivity, of 91.7 ± 2.6%. Conversely, a DL only model yielded an accuracy of <50% (F1 score 63%). Activations that initiate in gray matter, extend through white matter, and end in vascular regions are seen as the most discriminative expert-identified SOZ characteristics. Integration of expert knowledge of functional connectomics can not only enhance the performance of DL in localizing SOZ in RE but also lead toward potentially useful explanations of prevalent co-activation patterns in SOZ. RE with surgical outcomes and preoperative rs-fMRI studies can yield expert knowledge most salient for SOZ identification
Compassionate faces: Evidence for distinctive facial expressions associated with specific prosocial motivations
Compassion is a complex cognitive, emotional and behavioural process that has important real-world consequences for the self and others. Considering this, it is important to understand how compassion is communicated. The current research investigated the expression and perception of compassion via the face. We generated exemplar images of two compassionate facial expressions induced from two mental imagery tasks with different compassionate motivations (Study 1). Our kind- and empathic compassion faces were perceived differently and the empathic-compassion expression was perceived as best depicting the general definition of compassion (Study 2). Our two composite faces differed in their perceived happiness, kindness, sadness, fear and concern, which speak to their underling motivation and emotional resonance. Finally, both faces were accurately discriminated when presented along a compassion continuum (Study 3). Our results demonstrate two perceptually and functionally distinct facial expressions of compassion, with potentially different consequences for the suffering of others.CRB, PG, JAK and CJF were supported (MR/J009210/1) by the UK Medical Research Council (https://mrc.ukri.org/). JSL was supported by a grant (PP00P1_163758/1) from the Swiss National Science Foundation (www.snf.ch). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
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