3,262 research outputs found
Varactor diode assembly with low parasitic reactances
Development of varactor diode assembly overcomes parasitic reactances of conventional varactor packages. In specially constructed assembly very high idler-frequency to signal-frequency ratios are used to obtain low-noise operation over maximum bandwidth
Integrated-circuit balanced parametric amplifier
Amplifier, fabricated on single dielectric substrate, has pair of Schottky barrier varactor diodes mounted on single semiconductor chip. Circuit includes microstrip transmission line and slot line section to conduct signals. Main features of amplifier are reduced noise output and low production cost
The HCR-20 as a measure of reliable and clinically significant change in violence risk among secure psychiatric inpatients
Objective Periodic structured violence risk assessment is the principle method underlying treatment planning for mentally disordered offenders but little is known about how risk changes over time. We aimed to determine whether hospitalised patients underwent reliable clinical change in assessed risk. Method We used a pseudo-prospective longitudinal study design. Demographic, clinical and risk assessment data of adult inpatients (N=480) who had been routinely assessed with the HCR-20 on two to four occasions over a mean period of 17 months (SD=2) were collated. Linear mixed models regression was conducted to determine change over time on total, subscale, and individual item scores, and relative change between clinical and demographic groups. The Reliable Change Index was calculated to examine whether change was greater than that expected by measurement error; clinically significant change was defined as the extent to which HCR-20 scores reduced below previously reported scores for patients not requiring hospitalisation. Results HCR-20 total score (Estimate −0.42, 95% CI=−0.84, −0.01, p<.05; d=.20) and clinical score (Estimate=−0.42, 95% CI=−0.64, −0.20, p<.001; d=.36) reduced over assessments. Significant differences in change were evident between clinically and demographically defined groups. A maximum of 3% of individuals showed clinically significant reliable reductions in HCR-20 total scores. The scores of patients whose overall level of risk was judged to have decreased did not reduce between assessments. Conclusion Violence risk changes very little over the course of treatment although there is some variation between groups. Most change cannot be demonstrated to be reliable or clinically significant. Important clinical management decisions should not depend solely on evidence from changes in HCR-20 risk assessment
On the scaling spectrum of the Anderson impurity model
We consider the universal scaling behaviour of the Kondo resonance in the
strong coupling limit of the symmetric Anderson impurity model, using a
recently developed local moment approach. The resultant scaling spectrum is
obtained in closed form, and is dominated by long tails that in contrast to
previous work are found to exhibit a slow logarithmic decay rather than
power-law form, crossing over to characteristic Fermi liquid behaviour on the
lowest energy scales. The resultant theory, while naturally approximate, is
found to give very good agreement for essentially all frequencies with
numerical renormalization group calculations of both the single-particle
scaling spectrum and the self-energy.Comment: 16 pages, 4 embedded figure
Predictive validity of the short-term assessment of risk and treatability (START) for aggression and self-harm in a secure mental health service:gender differences
The START predicts aggressive outcomes and to some extent self-harm. However, it is not known whether gender moderates its performance. This study used routinely collected data to investigate the predictive ability of the START for aggression and self-harm in secure psychiatric patients. Utility of the START was examined separately for men and women. The START was a stronger predictor of aggression and self-harm in women than men. The specific risk estimates produced large effect sizes for the prediction of aggression and self-harm in women; none of the AUC values reached the threshold for a large effect size in the male sample
Predictive validity of the START for unauthorised leave and substance abuse in a secure mental health setting:a pseudo-prospective cohort study
Background Risk assessment and management is central to the nursing role in forensic mental health settings. The Short Term Assessment of Risk and Treatability (START) aims to support assessment through identification of risk and protective factors. It has demonstrated predictive validity for aggression; it also aims to aid risk assessment for unauthorised leave and substance abuse where its performance is relatively untested. Objectives To test the predictive validity of the START for unauthorised leave and substance abuse. Design A naturalistic, pseudo-prospective cohort study. Settings Four centres of a large UK provider of secure inpatient mental health services. Participants Inpatients resident between May 2011 and October 2013 who remained in the service for 3-months following assessment with the START by their clinical team. Exclusion criteria were missing assessment data in excess of prorating guidelines. Of 900 eligible patients 73 were excluded leaving a final sample size of n = 827 (response rate 91.9%). Mean age was 38.5 years (SD = 16.7); most participants (72.2%) were male; common diagnoses were schizophrenia-type disorders, personality disorders, organic disorders, developmental disorders and intellectual disability. Methods Routinely conducted START assessments were gathered. Subsequent incidents of substance abuse and unauthorised leave were coded independently. Positive and negative predictive values of low and elevated risk were calculated. Receiver Operating Characteristic analysis was conducted to ascertain the predictive accuracy of the assessments based on their sensitivity and specificity. Results Patient-based rates of unauthorised leave (2.4%) and substance abuse (1.6%) were low. The positive and negative predictive values for unauthorised leave were 5.9% and 98.4%; and for substance abuse 8.1% and 99.0%. The START specific risk estimate for unauthorised leave predicted its associated outcome (Area under the curve = .659, p < .05, 95% CI .531, .786); the substance abuse risk estimate predicted its outcome with a large effect size (Area under the curve = .723, p < .01, 95% CI .568, .879). Conclusions The study provides limited support for the START by demonstrating the predictive validity of its specific risk estimates for substance abuse and unauthorised leave. High negative predictive values suggest the tool may be of most utility in screening out low risk individuals from unnecessary restrictive interventions; very low positive predictive values suggest caution before implementing restrictive interventions in those rated at elevated risk. Researchers should investigate how multidisciplinary teams formulate risk assessments for these outcomes since they outperform the quantitative element of this tool
Role of assessment components and recent adverse outcomes in risk estimation and prediction:use of the Short Term Assessment of Risk and Treatability (START) in an adult secure inpatient mental health service
The Short Term Assessment of Risk and Treatability is a structured judgement tool used to inform risk estimation for multiple adverse outcomes. In research, risk estimates outperform the tool's strength and vulnerability scales for violence prediction. Little is known about what its’component parts contribute to the assignment of risk estimates and how those estimates fare in prediction of non-violent adverse outcomes compared with the structured components. START assessment and outcomes data from a secure mental health service (N=84) was collected. Binomial and multinomial regression analyses determined the contribution of selected elements of the START structured domain and recent adverse risk events to risk estimates and outcomes prediction for violence, self-harm/suicidality, victimisation, and self-neglect. START vulnerabilities and lifetime history of violence, predicted the violence risk estimate; self-harm and victimisation estimates were predicted only by corresponding recent adverse events. Recent adverse events uniquely predicted all corresponding outcomes, with the exception of self-neglect which was predicted by the strength scale. Only for victimisation did the risk estimate outperform prediction based on the START components and recent adverse events. In the absence of recent corresponding risk behaviour, restrictions imposed on the basis of START-informed risk estimates could be unwarranted and may be unethical
Use of the HCR-20 for violence risk assessment:views of clinicians working in a secure inpatient mental health setting
Purpose: To explore how raters combine constituent components of HCR-20 risk assessment for inpatient aggression, and how relevant they rate the tool for different diagnostic and demographic groups.Design/methodology/approach: A cross-sectional survey design was used. N=45 mental health clinicians working in a secure hospital responded to an online survey about their risk assessment practice.Findings: HCR-20 Historical and Clinical sub-scales were rated the most relevant to violence prediction but four of the five items rated most relevant were Historical items. A recent history of violence was rated more important for risk formulation than Historical and Risk management items, but not more important than Clinical items. While almost all respondents believed predictive accuracy would differ by gender, the tool was rated similarly in terms of its relevance for their client group by people working with men and women respectively.Research limitations/ implications: This was an exploratory survey and results should be verified using larger samples.Practical implications: Clinicians judge recent violence and Clinical items most important in inpatient violence risk assessment but may over-value historical factors. They believe that recent violent behaviour is important in risk formulation; however, while recent violence is an important predictor of future violence, the role it should play in SPJ schemes is poorly codified.Social implications: It is important that risk assessment is accurate in order to both protect the public and to protect patients from overly lengthy and restrictive detention.Originality/ value: Despite the vast number of studies examining the predictive validity of tools like HCR-20 very little research has examined the actual processes and decision-making behind formulation in clinical practice
A Fuzzy Logic Based Controller for the Automated Alignment of a Laser-beam-smoothing Spatial Filter
A fuzzy logic based controller for a laser-beam-smoothing spatial filter is described. It is demonstrated that a human operator's alignment actions can easily be described by a system of fuzzy rules of inference. The final configuration uses inexpensive, off-the-shelf hardware and allows for a compact, readily implemented embedded control system
High-performance Schottky diodes endure high temperatures
Fabrication process and aluminum/GaAs (gallium arsenide) coupling are used to produce Schottky diodes that have high cutoff frequencies and can withstand operating temperatures in excess of 500 C
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