This work presents results from detailed chemical kinetics calculations of electronically excited OH (A
2
Σ, denoted as OH
∗) and CH (A
2
Δ, denoted as CH
∗) chemiluminescent species in laminar ...premixed and non-premixed counterflow methane–air flames, at atmospheric pressure. Eight different detailed chemistry mechanisms, with added elementary reactions that account for the formation and destruction of the chemiluminescent species OH
∗ and CH
∗, are studied. The effects of flow strain rate and equivalence ratio on the chemiluminescent intensities of OH
∗, CH
∗ and their ratio are studied and the results are compared to chemiluminescent intensity ratio measurements from premixed laminar counterflow natural gas–air flames. This is done in order to numerically evaluate the measurement of equivalence ratio using OH
∗ and CH
∗ chemiluminescence, an experimental practise that is used in the literature. The calculations reproduced the experimental observation that there is no effect of strain rate on the chemiluminescent intensity ratio of OH
∗ to CH
∗, and that the ratio is a monotonic function of equivalence ratio. In contrast, the strain rate was found to have an effect on both the OH
∗ and CH
∗ intensities, in agreement with experiment. The calculated OH
∗/CH
∗ values showed that only five out of the eight mechanisms studied were within the same order of magnitude with the experimental data. A new mechanism, proposed in this work, gave results that agreed with experiment within 30%. It was found that the location of maximum emitted intensity from the excited species OH
∗ and CH
∗ was displaced by less than 65 and 115 μm, respectively, away from the maximum of the heat release rate, in agreement with experiments, which is small relative to the spatial resolution of experimental methods applied to combustion applications, and, therefore, it is expected that intensity from the OH
∗ and CH
∗ excited radicals can be used to identify the location of the reaction zone. Calculations of the OH
∗/CH
∗ intensity ratio for strained non-premixed counterflow methane–air flames showed that the intensity ratio takes different values from those for premixed flames, and therefore has the potential to be used as a criterion to distinguish between premixed and non-premixed reaction in turbulent flames.
Evidence suggests that the negative consequences of COVID-19 may extend far beyond its considerable death toll, having a significant impact on psychological well-being. Despite work highlighting the ...link between previous epidemics and elevated suicide rates, there is limited research on the relationship between the COVID-19 pandemic and suicidal thoughts and behaviors. Utilizing an online survey, the current study aimed to better understand the presence, and extent, of the association between COVID-19-related experiences and past-month suicidal thoughts and behaviors among adults in the United States recruited via Amazon Mechanical Turk (n = 907). Results support an association between several COVID-19-related experiences (i.e., general distress, fear of physical harm, effects of social distancing policies) and past-month suicidal ideation and suicide attempts. Further, a significant proportion of those with recent suicidal ideation explicitly link their suicidal thoughts to COVID-19. Exploratory analyses highlight a potential additional link between COVID-19 and suicidal behavior, suggesting that a portion of individuals may be intentionally exposing themselves to the virus with intent to kill themselves. These findings underscore the need for suicide risk screening and access to mental health services during the current pandemic. Particular attention should be paid to employing public health campaigns to disseminate information on such services to reduce the enormity of distress and emotional impairment associated with COVID-19 in the United States.
The Strategic Underreporting of Bank Risk Begley, Taylor A.; Purnanandam, Amiyatosh; Zheng, Kuncheng
The Review of financial studies,
10/2017, Letnik:
30, Številka:
10
Journal Article
Recenzirano
Odprti dostop
We show that banks significantly underreport the risk in their trading book when they have lower equity capital. Specifically, a decrease in a bank’s equity capital results in substantially more ...violations of its self-reported risk levels in the following quarter. Underreporting is especially frequent during the critical periods of high systemic risk and for banks with larger trading operations. We exploit a discontinuity in the expected benefit of underreporting present in Basel regulations to provide further support for a causal link between capitalsaving incentives and underreporting. Overall, we show that banks’ self-reported risk measures become least informative precisely when they matter the most.
•Conducted systematic review to examine use of machine learning (ML) in SITB research.•Thirty-five articles met criteria to be included in the review.•ML has resulted in improved SITB prediction ...accuracy.•ML has promise in identifying novel risk factors and interactions.
Machine learning techniques offer promise to improve suicide risk prediction. In the current systematic review, we aimed to review the existing literature on the application of machine learning techniques to predict self-injurious thoughts and behaviors (SITBs).
We systematically searched PsycINFO, PsycARTICLES, ERIC, CINAHL, and MEDLINE for articles published through February 2018.
Thirty-five articles met criteria to be included in the review. Included articles were reviewed by outcome: suicide death, suicide attempt, suicide plan, suicidal ideation, suicide risk, and non-suicidal self-injury. We observed three general aims in the use of SITB-focused machine learning analyses: (1) improving prediction accuracy, (2) identifying important model indicators (i.e., variable selection) and indicator interactions, and (3) modeling underlying subgroups. For studies with the aim of boosting predictive accuracy, we observed greater prediction accuracy of SITBs than in previous studies using traditional statistical methods. Studies using machine learning for variable selection purposes have both replicated findings of well-known SITB risk factors and identified novel variables that may augment model performance. Finally, some of these studies have allowed for subgroup identification, which in turn has helped to inform clinical cutoffs.
Limitations of the current review include relatively low paper sample size, inconsistent reporting procedures resulting in an inability to compare model accuracy across studies, and lack of model validation on external samples.
We concluded that leveraging machine learning techniques to further predictive accuracy and identify novel indicators will aid in the prediction and prevention of suicide.
The original European League Against Rheumatism recommendations for managing fibromyalgia assessed evidence up to 2005. The paucity of studies meant that most recommendations were 'expert opinion'.
A ...multidisciplinary group from 12 countries assessed evidence with a focus on systematic reviews and meta-analyses concerned with pharmacological/non-pharmacological management for fibromyalgia. A review, in May 2015, identified eligible publications and key outcomes assessed were pain, fatigue, sleep and daily functioning. The Grading of Recommendations Assessment, Development and Evaluation system was used for making recommendations.
2979 titles were identified: from these 275 full papers were selected for review and 107 reviews (and/or meta-analyses) evaluated as eligible. Based on meta-analyses, the only 'strong for' therapy-based recommendation in the guidelines was exercise. Based on expert opinion, a graduated approach, the following four main stages are suggested underpinned by shared decision-making with patients. Initial management should involve patient education and focus on non-pharmacological therapies. In case of non-response, further therapies (all of which were evaluated as 'weak for' based on meta-analyses) should be tailored to the specific needs of the individual and may involve psychological therapies (for mood disorders and unhelpful coping strategies), pharmacotherapy (for severe pain or sleep disturbance) and/or a multimodal rehabilitation programme (for severe disability).
These recommendations are underpinned by high-quality reviews and meta-analyses. The size of effect for most treatments is relatively modest. We propose research priorities clarifying who will benefit from specific interventions, their effect in combination and organisation of healthcare systems to optimise outcome.
A popular model of human sensorimotor learning suggests that a fast process and a slow process work in parallel to produce the canonical learning curve (Smith et al., 2006). Recent evidence supports ...the subdivision of sensorimotor learning into explicit and implicit processes that simultaneously subserve task performance (Taylor et al., 2014). We set out to test whether these two accounts of learning processes are homologous. Using a recently developed method to assay explicit and implicit learning directly in a sensorimotor task, along with a computational modeling analysis, we show that the fast process closely resembles explicit learning and the slow process approximates implicit learning. In addition, we provide evidence for a subdivision of the slow/implicit process into distinct manifestations of motor memory. We conclude that the two-state model of motor learning is a close approximation of sensorimotor learning, but it is unable to describe adequately the various implicit learning operations that forge the learning curve. Our results suggest that a wider net be cast in the search for the putative psychological mechanisms and neural substrates underlying the multiplicity of processes involved in motor learning.
Cold biopsy forceps polypectomy (CBP) is often used for the removal of diminutive polyps. The efficacy of the technique has not been thoroughly assessed. The aim of this study was to prospectively ...assess the efficacy of CBP for removing diminutive polyps.
This was a prospective study from St Vincent's Hospital, a tertiary referral hospital in Melbourne, Australia. A total of 143 patients were screened and 52 patients with ≥ 1 diminutive polyps were enrolled. CBP was used to resect diminutive polyps until no polyp tissue was visible. The polyp base was then resected using endoscopic mucosal resection (EMR) with a 1 - 2-mm margin. The CBP and EMR samples were compared to assess completeness of the resection.
Overall 39 % (21 / 54) of diminutive polyps were completely resected using CBP. After binary logistic regression analysis, polyp histology was found to be predictive of resection, with complete resection of 62 % (13 / 21) for adenomas and 24 % (8 / 33) for hyperplastic polyps (odds ratio 5.1; P = 0.008). The size and number of bites taken with the forceps were not predictive of complete response.
Within the limitations of a modest sample size, CBP appears to be inadequate treatment for the removal of diminutive polyps.
We study the key drivers of security design in the residential mortgage-backed security (RMBS) market during the run-up to the subprime mortgage crisis. We show that deals with a higher level of ...equity tranche have a significantly lower delinquency rate conditional on observable loan characteristics. The effect is concentrated within pools with a higher likelihood of asymmetric information between deal sponsors and potential buyers of the securities. Further, securities sold from high-equity-tranche deals command higher prices conditional on their credit ratings. Overall, our results show that the goal of security design in this market was not only to exploit regulatory arbitrage, but also to mitigate information frictions that were pervasive in this market.
We present a study of the distribution of radio jet position angles of radio galaxies over an area of 1 square degree in the ELAIS N1 field. ELAIS N1 was observed with the Giant Metrewave Radio ...Telescope at 612 MHz to an rms noise level of 10 μJy and angular resolution of 6 arcsec × 5 arcsec. The image contains 65 resolved radio galaxy jets. The spatial distribution reveals a prominent alignment of jet position angles along a ‘filament’ of about 1°. We examine the possibility that the apparent alignment arises from an underlying random distribution and find that the probability of chance alignment is less than 0.1 per cent. An angular covariance analysis of the data indicates the presence of spatially coherence in position angles on scales >0
$_{.}^{\circ}$
5. This angular scales translates to a comoving scale of >20 Mpc at a redshift of 1. The implied alignment of the spin axes of massive black holes that give rise to the radio jets suggest the presence of large-scale spatial coherence in angular momentum. Our results reinforce prior evidence for large-scale spatial alignments of quasar optical polarization position angles.