Mechanically induced current and quantum evaporation from Luttinger liquids

We investigate transport through a tunnelling junction between an uncorrelated metallic lead and a Luttinger liquid when the latter is subjected to a time dependent perturbation. The tunnelling current as well as the electron energy distribution function are found to be strongly affected by the perturbation due to generation of harmonics in the density oscillations. Using a semiconducting lead instead of a metallic one results in electrons being injected into the lead even without applied voltage. Some applications to carbon nanotubes are discussed.Comment: 7 pages, 2 figures (eps files

Con: Most clinical risk scores are useless

While developing prediction models has become quite popular both in nephrology and in medicine in general, most models have not been implemented in clinical practice on a larger scale. This should be no surprise, as the majority of published models has been shown to be poorly reported and often developed using inappropriate methods. The main problems identified relate to either using too few candidate predictors (based on univariable P </p

Towards the best kidney failure prediction tool: a systematic review and selection aid

Background. Prediction tools that identify chronic kidney disease (CKD) patients at a high risk of developing kidney failure have the potential for great clinical value, but limited uptake. The aim of the current study is to systematically review all available models predicting kidney failure in CKD patients, organize empirical evidence on their validity and ultimately provide guidance in the interpretation and uptake of these tools.Methods. PubMed and EMBASE were searched for relevant articles. Titles, abstracts and full-text articles were sequentially screened for inclusion by two independent researchers. Data on study design, model development and performance were extracted. The risk of bias and clinical usefulness were accessed and combined in order to provide recommendations on which models to use.Results. Of 2183 screened studies, a total of 42 studies were included in the current review. Most studies showed high discriminatory capacity and the included predictors had large overlap. Overall, the risk of bias was high. Slightly less than half the studies (48%) presented enough detail for the use of their prediction tool in practice and few models were externally validated.Conclusions. The current systematic review may be used as a tool to select the most appropriate and robust prognostic model for various settings. Although some models showed great potential, many lacked clinical relevance due to being developed in a prevalent patient population with a wide range of disease severity. Future research efforts should focus on external validation and impact assessment in clinically relevant patient populations.Clinical epidemiolog

Spin-dependent transport in a Luttinger liquid

We develop a detailed theory for spin transport in a one-dimensional quantum wire described by Luttinger liquid theory. A hydrodynamic description for the quantum wire is supplemented by boundary conditions taking into account the exchange coupling between the magnetization of ferromagnetic reservoirs and the boundary magnetization in the wire. Spin-charge separation is shown to imply drastic and qualitative consequences for spin-dependent transport. In particular, the spin accumulation effect is quenched except for fine-tuned parameter regimes. We propose several feasible setups involving an external magnetic field to detect this phenomenon in transport experiments on single-wall carbon nanotubes. In addition, electron-electron backscattering processes, which do not have an important effect on thermodynamic properties or charge transport, are shown to modify spin-dependent transport through long quantum wires in a crucial way.Comment: 23 pages, 4 figure

The association between pain perception and care dependency in older nursing home residents: a prospective cohort study

Objectives: Maintenance of independence is a challenge for nursing home residents whose pain is often substantial. The objective of this study was to explore the relationship between pain perception and care dependency in a population of Dutch nursing home residents.Design: Prospective cohort study. Setting and participants: Dutch nursing home residents aged 65 or older, excluding residents with a severe cognitive impairment.Methods: The Numeric Rating Scale (NRS) was used to rate pain perception from 0 to 10 in half-point increments and the Care Dependency Scale (CDS) to measure care dependency, with scores ranging from 15 (completely care dependent) to 75 (fully independent). Both measurements were repeated after a 2-month follow-up. Multiple linear regression analysis was used to adjust for potential confounders. Missing data were dealt with by performing tenfold multiple imputation.Results: A total of 1256 residents (65% women, mean age 83 years) were included. At baseline, the median NRS pain score was 3.0 (interquartile range 0.0-6.0) and the mean CDS score was 55.9 (SD 11.5). Cross-sectionally, for 1-point increase in pain score, care dependency increased 0.65 points [95% confidence interval (CI) 0.46-0.83]. More pain at baseline was associated with slightly lower care dependency after 2 months (beta 0.20, 95% CI 0.01-0.39). Compared with residents whose pain decreased over 2 months, residents with stable pain or increased pain had a 2.27-point (95% CI 0.83-3.70) and 2.39 point (95% CI 0.87-3.90) greater increase in care dependency, respectively.Conclusions and implications: Pain perception and care dependency are associated in a population of older nursing home residents, and stable or increased pain is associated with increased care dependency progression. The findings of this study emphasize that pain and care dependency should not be assessed nor treated independently. (C) 2020 The Author(s). Published by Elsevier Inc. on behalf of AMDA - The Society for Post-Acute and Long-Term Care Medicine. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).Clinical epidemiolog

Charge Screening Effect in Metallic Carbon Nanotubes

Charge screening effect in metallic carbon nanotubes is investigated in a model including the one-dimensional long-range Coulomb interaction. It is pointed out that an external charge which is being fixed spatially is screened by internal electrons so that the resulting object becomes electrically neutral. We found that the screening length is given by about the diameter of a nanotube.Comment: 11 pages, 6 figure

Appraising prediction research: a guide and meta-review on bias and applicability assessment using the Prediction model Risk Of Bias ASsessment Tool (PROBAST)

Over the past few years, a large number of prediction models have been published, often of poor methodological quality. Seemingly objective and straightforward, prediction models provide a risk estimate for the outcome of interest, usually based on readily available clinical information. Yet, using models of substandard methodological rigour, especially without external validation, may result in incorrect risk estimates and consequently misclassification. To assess and combat bias in prediction research the prediction model risk of bias assessment tool (PROBAST) was published in 2019. This risk of bias (ROB) tool includes four domains and 20 signalling questions highlighting methodological flaws, and provides guidance in assessing the applicability of the model. In this paper, the PROBAST will be discussed, along with an in-depth review of two commonly encountered pitfalls in prediction modelling that may induce bias: overfitting and composite endpoints. We illustrate the prevalence of potential bias in prediction models with a meta-review of 50 systematic reviews that used the PROBAST to appraise their included studies, thus including 1510 different studies on 2104 prediction models. All domains showed an unclear or high ROB; these results were markedly stable over time, highlighting the urgent need for attention on bias in prediction research. This article aims to do just that by providing (1) the clinician with tools to evaluate the (methodological) quality of a clinical prediction model, (2) the researcher working on a review with methods to appraise the included models, and (3) the researcher developing a model with suggestions to improve model quality.Clinical epidemiolog

Predicting mortality risk on dialysis and conservative care: development and internal validation of a prediction tool for older patients with advanced chronic kidney disease

Background. Conservative care (CC) may be a valid alternative to dialysis for certain older patients with advanced chronic kidney disease (CKD). A model that predicts patient prognosis on both treatment pathways could be of value in shared decision-making. Therefore, the aim is to develop a prediction tool that predicts the mortality risk for the same patient for both dialysis and CC from the time of treatment decision.Methods. CKD Stage 4/5 patients aged >= 70 years, treated at a single centre in the Netherlands, were included between 2004 and 2016. Predictors were collected at treatment decision and selected based on literature and an expert panel. Outcome was 2-year mortality. Basic and extended logistic regression models were developed for both the dialysis and CC groups. These models were internally validated with bootstrapping. Model performance was assessed with discrimination and calibration.Results. In total, 366 patients were included, of which 126 chose CC. Pre-selected predictors for the basic model were age, estimated glomerular filtration rate, malignancy and cardiovascular disease. Discrimination was moderate, with optimism-corrected C-statistics ranging from 0.675 to 0.750. Calibration plots showed good calibration.Conclusions. A prediction tool that predicts 2-year mortality was developed to provide older advanced CKD patients with individualized prognosis estimates for both dialysis and CC. Future studies are needed to test whether our findings hold in other CKD populations. Following external validation, this prediction tool could be used to compare a patient's prognosis on both dialysis and CC, and help to inform treatment decision-making.Clinical epidemiolog

The Amsterdam studies of acute psychiatry I (ASAP-I); A prospective cohort study of determinants and outcome of coercive versus voluntary treatment interventions in a metropolitan area

Background: The overall number of involuntary admissions is increasing in many European countries. Patients with severe mental illnesses more often progress to stages in which acute, coercive treatment is warranted. The number of studies that have examined this development and possible consequences in terms of optimizing health care delivery in emergency psychiatry is small and have a number of methodological shortcomings. The current study seeks to examine factors associated with compulsory admissions in the Amsterdam region, taking into account a comprehensive model with four groups of predictors: patient vulnerability, social support, responsiveness of the health care system and treatment adherence. Methods/Design: This paper describes the design of the Amsterdam Study of Acute Psychiatry-I (ASAP-I). The study is a prospective cohort study, with one and two-year follow-up, comparing patients with and without forced admission by means of a selected nested case-control design. An estimated total number of 4,600 patients, aged 18 years and over, consecutively coming into contact with the Psychiatric Emergency Service Amsterdam (PESA) are included in the study. From this cohort, a randomly selected group of 125 involuntary admitted subjects and 125 subjects receiving non-coercive treatment are selected for further evaluation and comparison. First, socio-demographic, psychopathological and network characteristics, and prior use of health services will be described for all patients who come into contact with PESA. Second, the in-depth study of compulsory versus voluntary patients will examine which patient characteristics are associated with acute compulsory admission, also taking into account social network and healthcare variables. The third focus of the study is on the associations between patient vulnerability, social support, healthcare characteristics and treatment adherence in a two-year follow-up for patients with or without involuntarily admittance at the index consultation. Discussion: The current study seeks to establish a picture of the determinants of acute compulsory admissions in the Netherlands and tries to gain a better understanding of the association with the course of illness and patient's perception of services and treatment adherence. The final aim is to find specific patient and health care factors that can be influenced by adjusting treatment programs in order to reduce the number of involuntary admissions

Suicide risk, personality disorder and hospital admission after assessment by psychiatric emergency services

Background: The main objectives of the mobile Psychiatric Emergency Services (PES) in the Netherlands are to assess the presence of a mental disorder, to estimate risk to self or others, and to initiate continuity of care, including psychiatric hospital admission. The aim of this study was to assess the associations between the level of suicidality and risk of voluntary or involuntary admission in patients with and without a personality disorder who were presented to mobile PES. Methods: Observational data were obtained in three areas of the Netherlands from 2007 to 2016. In total, we included 71,707 contacts of patients aged 18 to 65 years. The outcome variable was voluntary or involuntary psychiatric admission. Suicide risk and personality disorder were assessed by PES-clinicians. Multivariable regression analysis was used to explore associations between suicide risk, personality disorder, and voluntary or involuntary admission. Results: Independently of the level of suicide risk, suicidal patients diagnosed with personality disorder were less likely to be admitted voluntarily than those without such a diagnosis (admission rate .37 versus .46 respectively). However, when the level of suicide risk was moderate or high, those with a personality disorder who were admitted involuntarily had the same probability of involuntary admission as those without such a disorder. Conclusions: While the probability of voluntary admission was lower in those diagnosed with a personality disorder, independent of the level of suicidality, the probability of involuntary admission was only lower in those whose risk of suicide was low. Future longitudinal studies should investigate the associations between (involuntary) admission and course of suicidality in personality disorder