PT-symmetric, non-Hermitian quantum many-body physics-a methodological perspective.

We review the methodology to theoretically treat parity-time- (PT-) symmetric, non-Hermitian quantum many-body systems. They are realized as open quantum systems withPTsymmetry and couplings to the environment which are compatible.PT-symmetric non-Hermitian quantum systems show a variety of fascinating properties which single them out among generic open systems. The study of the latter has a long history in quantum theory. These studies are based on the Hermiticity of the combined system-reservoir setup and were developed by the atomic, molecular, and optical physics as well as the condensed matter physics communities. The interest of the mathematical physics community inPT-symmetric, non-Hermitian systems led to a new perspective and the development of the elegant mathematical formalisms ofPT-symmetric and biorthogonal quantum mechanics, which do not make any reference to the environment. In the mathematical physics research, the focus is mainly on the remarkable spectral properties of the Hamiltonians and the characteristics of the corresponding single-particle eigenstates. Despite being non-Hermitian, the Hamiltonians can show parameter regimes, in which all eigenvalues are real. To investigate emergent quantum many-body phenomena in condensed matter physics and to make contact to experiments one, however, needs to study expectation values of observables and correlation functions. One furthermore, has to investigate statistical ensembles and not only eigenstates. The adoption of the concepts ofPT-symmetric and biorthogonal quantum mechanics by parts of the condensed matter community led to a controversial status of the methodology. There is no consensus on fundamental issues, such as, what a proper observable is, how expectation values are supposed to be computed, and what adequate equilibrium statistical ensembles and their corresponding density matrices are. With the technological progress in engineering and controlling open quantum many-body systems it is high time to reconcile the Hermitian with thePT-symmetric and biorthogonal perspectives. We comprehensively review the different approaches, including the overreaching idea of pseudo-Hermiticity. To motivate the Hermitian perspective, which we propagate here, we mainly focus on the ancilla approach. It allows to embed a non-Hermitian system into a larger, Hermitian one. In contrast to other techniques, e.g. master equations, it does not rely on any approximations. We discuss the peculiarities ofPT-symmetric and biorthogonal quantum mechanics. In these, what is considered to be an observable depends on the Hamiltonian or the selected (biorthonormal) basis. Crucially in addition, what is denoted as an 'expectation value' lacks a direct probabilistic interpretation, and what is viewed as the canonical density matrix is non-stationary and non-Hermitian. Furthermore, the non-unitarity of the time evolution is hidden within the formalism. We pick up several model Hamiltonians, which so far were either investigated from the Hermitian perspective or from thePT-symmetric and biorthogonal one, and study them within the respective alternative framework. This includes a simple two-level, single-particle problem but also a many-body lattice model showing quantum critical behavior. Comparing the outcome of the two types of computations shows that the Hermitian approach, which, admittedly, is in parts clumsy, always leads to results which are physically sensible. In the rare cases, in which a comparison to experimental data is possible, they furthermore agree to these. In contrast, the mathematically elegantPT-symmetric and biorthogonal approaches lead to results which, are partly difficult to interpret physically. We thus conclude that the Hermitian methodology should be employed. However, to fully appreciate the physics ofPT-symmetric, non-Hermitian quantum many-body systems, it is also important to be aware of the main concepts ofPT-symmetric and biorthogonal quantum mechanics. Our conclusion has far reaching consequences for the application of Green function methods, functional integrals, and generating functionals, which are at the heart of a large number of many-body methods. They cannot be transferred in their established forms to treatPT-symmetric, non-Hermitian quantum systems. It can be considered as an irony of fate that these methods are available only within the mathematical formalisms ofPT-symmetric and biorthogonal quantum mechanics.

The role of trust and hope in antipsychotic medication reviews between GPs and service users a realist review.

BACKGROUND: Increasing number of service users diagnosed with schizophrenia and psychosis are being discharged from specialist secondary care services to primary care, many of whom are prescribed long-term antipsychotics. It is unclear if General Practitioners (GPs) have the confidence and experience to appropriately review and adjust doses of antipsychotic medication without secondary care support. AIM: To explore barriers and facilitators of conducting antipsychotic medication reviews in primary care for individuals with no specialist mental health input. DESIGN & SETTING: Realist review in general practice settings. METHOD: A realist review has been conducted to synthesise evidence on antipsychotic medication reviews conducted in primary care with service users diagnosed with schizophrenia or psychosis. Following initial scoping searches and discussions with stakeholders, a systematic search and iterative secondary searches were conducted. Articles were systematically screened and analysed to develop a realist programme theory explaining the contexts (C) and mechanisms (M) which facilitate or prevent antipsychotic medication reviews (O) in primary care settings, and the potential outcomes of medication reviews. RESULTS: Meaningful Antipsychotic medication reviews may not occur for individuals with only primary care medical input. Several, often mutually reinforcing, mechanisms have been identified as potential barriers to conducting such reviews, including low expectations of recovery for people with severe mental illness, a perceived lack of capability to understand and participate in medication reviews, linked with a lack of information shared in appointments between GPs and Service Users, perceived risk and uncertainty regarding antipsychotic medication and illness trajectory. CONCLUSIONS: The review identified reciprocal and reinforcing stereotypes affecting both GPs and service users. Possible mechanisms to counteract these barriers are discussed, including realistic expectations of medication, and the need for increased information sharing and trust between GPs and service users.

Corrective osteotomies of femur and tibia: which factors influence bone healing?

INTRODUCTION: Corrective osteotomies of the lower limb are standard procedures in orthopedic surgery. Still, there is only limited research on factors affecting bone healing after osteotomies. We hypothesize that especially the location of the osteotomy, smoking status and BMI affect bone healing. MATERIAL AND METHODS: The healing process of 547 patients who underwent osteotomies of the lower limb (259 female, 288 male; average 40.6 years, range 14-77) was evaluated. To assess bone healing, participants were divided into three groups by bone healing duration ( < 5/5-8/ > 8 months). Differences in healing duration related to the anatomic level of the osteotomy (diaphysis vs. metaphysis), age, gender, smoking status, BMI, and modus of the osteotomy (open vs. closed wedge) were tested for significance using an ordinal regression analysis. RESULTS: A significant correlation between bone healing and the anatomical level of the osteotomy on femur and tibia and the patients' smoking status was found. The odds of the diaphysis considering bone healing was 0.187 (95% CI, 0.08-0.44) times that of the metaphysis (Wald χ2(1) = 14.597, p < 0.000). The odds ratio of smokers considering bone healing was 0.192 (95% CI, 0.11-0.33) times that of non-smokers (Wald χ2(1) = 35.420, p < 0.000). All other analyzed factors did not show a significant correlation with bone healing. CONCLUSIONS: Smoking status and the localization of the osteotomy on femur and tibia (diaphysis vs. metaphysis) are significantly correlated with bone healing duration. In line with current literature emphasizing the detrimental effect of smoking on bone healing, our findings should encourage surgeons to think twice about the indication to perform osteotomies on smokers. Furthermore, if applicable, osteotomies should be performed in the metaphyseal areas of femur and tibia.

No change in patellar height following open wedge high tibial osteotomy using a novel femur-referenced measurement method.

BACKGROUND: Open wedge high tibial osteotomy (HTO) can influence the tibial slope and thereby the landmarks of currently used patellar height indices. The purpose of this retrospective study was to compare and validate a new femur-referenced patella height measurement method to currently used patellar height indices in a cohort of HTO patients. METHODS: Patellar height (Caton-Deschamps, Blackburne-Peel and Insall-Salvati Indices and our newly developed Femoral Patellar Height Index) as well as tibial slope were analysed. Full-weight-bearing long-leg anteroposterior radiographs as well as anteroposterior and lateral radiographs of the knee in 0° of extension were used. Radiographs were performed preoperatively, and at six weeks, three, six, 12 and 18months postoperatively. Measurements were recorded twice by two observers. The second observation was performed after a delay of three months. RESULTS: A total of 99 patients with a mean age of 46.2±8years were included. A statistically significant pre- to postoperative increase in tibial slope was found in all methods. Patellar height decreased according to Caton-Deschamps and Blackburne-Peel Indices. The Insall-Salvati Index as well as the novel Femoral Patellar Height Index remained unchanged. Intra-rater (interclass correlation coefficient (ICC) 0.914-0.998) and inter-rater (ICC 0.955-0.989) reliability were highest in the new index. CONCLUSION: Detected changes of patellar height following open wedge HTO depend on the method used. Tibial slope increases following surgery. Our new index with a femoral reference for measuring patellar height was validated and good to excellent intra- and inter-rater reliability were demonstrated. Following HTO, the Femoral Patellar Height Index can be recommended as a standardized method to measure patellar height.

[Malnutrition in Elderly Trauma Patients - Comparison of Two Assessment Tools]. / Die Erfassung des Ernährungsstatus alterstraumatologischer Patienten ­ ein Vergleich zweier etablierter Screeningmethoden.

Background: The prevalence of malnutrition in hospitalised patients is reported to be between 16 and 55 % across disciplines. Within hospital care, screening for malnutrition is required. However, in orthopaedics and trauma surgery, there is still no generally accepted recommendation for the methods for such a data survey. In the present study, the following aspects are to be investigated with the help of two established scores: (1) the prevalence of malnutrition in the patient population of geriatric trauma care, and (2) the correlation between methods of data survey. Material and Methods: Between June 2014 and June 2015, a consecutive series of hospitalised trauma patients were studied prospectively with two validated screening instruments to record nutritional status. The study was carried out at a municipal trauma surgery hospital, which is a first level interregional trauma centre as well as a university hospital. The Nutritional Risk Screening (NRS) and the Mini Nutritional Assessment (MNA Short and Long Form) were used. All patients were divided into three age groups: < 65 years, 65-80 years, and > 80 years. The prevalence of malnutrition in geriatric trauma patients and the correlation between the screening instruments were determined. For a better comparison, prescreening and main assessment were applied to all patients. For statistical evaluation, both quantitative and semi-quantitative parameters were used. Furthermore, the Kolmogorov-Smirnov test, Spearman's correlation analysis and the chi-square test were applied. These tests were two-sided and had a level of significance of 5 %. The present study was partially funded by the Oskar-Helene-Heim Foundation. Results: 521 patients (43.8 % women, 56.2 % men), with a mean age of 53.96 ± 18.13 years, were statistically evaluated within the present study. Depending on the method of the data survey, malnutrition (NRS≥3) in geriatric trauma patients varied from 31.3 % (65-80 years) to 60 % (> 80 years). With MNA, 28.8 and 54.3 % of patients were at risk of malnutrition (MNA 17-23.5), while the fractions of patients already suffering from malnutrition (MNA < 17) were 5.4 and 8.6 %, respectively. The correlation between the NRS and MNA total scores increases with the age of the patients. The correlation coefficient for patients under 65 years is r = - 0.380, while among patients aged between 65 and 80, it is r = - 0.481, and for patients over 80 years, there is a medium to strong correlation of r = - 0.638 (each with a Spearman correlation of p < 0.001). For the total population as well as the different age groups, statistically significant correlations were recorded between the categorised scores (chi-square test for linear trend, p < 0.001). Summary: The present study demonstrates high prevalence of malnutrition among the geriatric trauma patients. Because of its easy and rapid application, the NRS has an advantage in clinical use. It was shown that the two methods of data survey were highly correlated.

[Return to sport after surgical treatment of a posterior cruciate ligament injury : A retrospective study of 60 patients]. / Rückkehr in den Sport nach operativer Versorgung einer hinteren Kreuzbandverletzung : Eine retrospektive Untersuchung von 60 Patienten.

BACKGROUND: Injuries of the posterior cruciate ligament (PCL) lead to an initial reduction of sporting activity. However, in previous studies, return to sport after operative treatment of PCL injuries has been analysed insufficiently. The aim of this study was (1) to determine the rate of return to sport in physically active patients, (2) to analyse possible changes in sporting activities and (3) to examine the influence of the severity of the initial injury. PATIENTS AND METHODS: Within a retrospective clinical and radiological follow-up at least 24 months after surgery (80.3 ± 28.2 months), 60 patients (44.8 ± 12.1 years) with surgically treated isolated or combined PCL injuries were included in the study. Pre-accidental and post-operative sporting activities were queried and compared in a standardised questionnaire. Possible differences with respect to the initial injury severity (Cooper classification) were examined. RESULTS: The return-to-sport rate of the physically active patients was 87.0 %. 17.6 % of patients with a combined PCL injury and 4.8 % of patients with isolated PCL injury were not able to return to sport. Significant reductions in the frequency of exercise (p = 0.0087), the duration of exercise (p = 0.0003) and the amount of regularly performed sports (p < 0.0001) were found. A change from high-impact sports to low-impact sports was noted. CONCLUSION: Patients with operatively treated PCL injuries can return to sport. However, for competitive athletes an injury to the PCL can lead to the end of their career. A reduction of sporting activities and a change from high-impact sports to low-impact sports can be expected. A persisting inability to return to sporting activities in patients with isolated PCL injuries cannot be assumed.

[The Meaning of Neurological and Psychiatric Disease and Addiction for Pregnancy Outcome: A Case-control Study of the Birth Cohort 2010-2012]. / Die Bedeutung neurologischer, psychiatrischer und Suchterkrankungen für den Schwangerschaftsausgang: Fall-Kontroll-Studie der Geburtsjahrgänge 2010-2012.

BACKGROUND AND AIMS: The worldwide prevalence of neurological and psychiatric illnesses is steadily increasing. Consequently women of childbearing age are concerned as well. This survey examines the question of what kind of effects these illnesses have prenatally on mother and child. METHODS: In a case-control study, differences in pregnancy, birth process, and birth outcome were associated with a neurological or psychiatric illness of the expectant mother. 325 pregnant women with 331 born children were identified as cases, which were compared to 5 103 non diseased pregnant women with 5 195 born children. RESULTS: The age of the mother for admission was significantly lower in the case group than in the control group. The number of previous gestations and the number of previous induced abortion were significantly higher in the case group. Also the BMI before pregnancy and the length of stationary stay showed significantly higher values in the case group. Children belonging to the case group were born significantly earlier, had a lower birth weight, height, and head circumference. Furthermore Apgar scores were significantly lower in the case group. The frequency of postpartum stationary stay in a children's clinic as well as the length of stationary stay were also significantly higher when the mother suffered from a neurological or a psychiatric illness. CONCLUSION: The present results point out the correlation between most of the tested parameters and a neuropsychiatric illness of the newborn's mother. The interdisciplinary collaboration between gynecologists and pediatricians, as well as neurologists and psychiatrists should be strengthened to guarantee the best possible medical care.

[Patella dislocation: an algorithm for diagnostic and treatment considering the rotation]. / Patellaluxation: Diagnostik- und Behandlungsalgorithmus unter Berücksichtigung der Torsion.

BACKGROUND: Patella dislocation and re-dislocation are common diseases. Although patella dislocation is frequent, it always poses a challenge concerning diagnostics and therapy. Mixed forms of pathological disorder in the patellofemoral joint make the analysis of the malalignment and the choice of the correct treatment more difficult. MATERIAL AND METHODS: By reviewing the available literature of the last few years and taking into account considerations concerning the malalignment, an overview of the necessary diagnostics can be given. Radiographs and MRI are essential parts of the diagnostics after a traumatic patella dislocation. After re-dislocation, more extensive diagnostics are required to determine all pathological aspects of the malalignment. In this situation, a CT scan for measuring the torsion of the femur and the tibia as well as the TT-TG distance (tibial tubercle - trochlea groove), and the full weight-bearing long leg standing radiograph are part of the fundamental diagnostics. RESULTS: The results that are presented in the literature provide some indications for a successful treatment. In consideration of the thorough analysis of the malalignment, the torsional correction of the femur and/or the tibia gains a new importance in the patellofemoral joint. The presented algorithm for diagnostics and treatment should make the decision for the best treatment easier. CONCLUSION: The proposed algorithm for diagnostics and treatment is only partially founded on evidence-based results. Moreover, it takes into consideration reflections concerning the biomechanics of the patellofemoral joint and the realignment of this joint.

Assessment of the nature of residual masses at end of treatment in lymphoma patients using volume perfusion computed tomography.

OBJECTIVES: To determine the diagnostic benefit of volume perfusion computed tomography (VPCT) at end of treatment for response assessment in lymphoma patients. METHODS: Seventy-five patients with different lymphoma subtypes were included: 50/75 patients had residual masses at end of treatment, 26/50 patients underwent VPCT at baseline and at end of treatment, and 24/50 patients only had end-of-treatment VPCTs. We evaluated the size of the main lymphoma mass, its blood flow (BF), blood volume (BV) and k-trans, calculated ratios (baseline and end of treatment) as well as sensitivity/specificity/negative (NPV)/positive predictive values (PPV). For VPCT at end of treatment, a cutoff threshold between responders and non-responders was calculated. RESULTS: For patients undergoing VPCT at baseline and end of treatment, reduction in size, BF, BV and k-trans was significant (P < 0.001). Identification of non-response was reached at: <53% reduction in size (sensitivity/specificity/accuracy/PPV/NPV of 88.89%/62.5%/80.77%/84.21%/71.43%), <15% reduction of BF (sensitivity/specificity/accuracy/PPV/NPV of 100%/37.5%/80.77%/0.26%/100%), or <45% reduction of k-trans (sensitivity/specificity/accuracy/PPV/NPV of 88.89%/75%/84.62%/88.89%/75%). In the subgroup undergoing VPCT at end of treatment, BF >18.51 ml/100 ml indicated non-responsiveness (sensitivity 92.86%, specificity 72.73%, accuracy 84%, PPV 81.25%, NPV 88.89%). CONCLUSIONS: VPCT seems adequate for assessment of lymphoma response at end of treatment. The degree of residual lymphoma perfusion at end of treatment helps to identify patients likely to remain in remission 1 year after completion of therapy. KEY POINTS: • Volume perfusion computed tomography (VPCT) offers measurements for assessing tumour response. • Perfusion parameter changes measured by VPCT correlate with antitumour therapy response. • In lymphoma, baseline and end-of-treatment perfusion parameter ratios can predict response. • Perfusion measurements after treatment identify patients likely to remain in remission.

Predictors of first discharge and subsequent survival in patients with automatic implantable cardioverter-defibrillators.

BACKGROUND: Two hundred eighteen patients were evaluated in a two-phase approach (time to first appropriate discharge, survival after discharge) to identify factors that may be related to maximal benefit derived from use of an automatic implantable cardioverter-defibrillator (AICD). METHODS AND RESULTS: One hundred ninety-seven patients survived implantation of AICD, with or without concomitant cardiac surgery. One hundred five patients had an AICD discharge associated with syncope, presyncope, documented sustained ventricular tachycardia or fibrillation, or sleep at 9.1 +/- 11.1 months after implantation. Patients survived 23.8 +/- 18.0 months after AICD discharge. Left ventricular dysfunction (p = 0.008 for ejection fraction less than 25%) was associated with earlier AICD discharge and shortened survival after AICD discharge (p = 0.008 for ejection fraction less than 25%; p = 0.01 for New York Heart Association functional class III and IV). beta-Blocker administration (p = 0.006) and coronary bypass surgery (p = 0.06) were associated with later AICD discharge. Coronary bypass surgery (p = 0.035) but not beta-blockers was associated with more prolonged survival after AICD discharge. CONCLUSIONS: These data suggest that a relatively easy algorithm can be applied to predict which patient will benefit most from AICD implantation.

Impending sudden cardiac death: treatment with myocardial revascularization and the automatic implantable cardioverter defibrillator.

Myocardial revascularization and implantation of the automatic implantable cardioverter defibrillator (AICD) have individually been shown to improve survival in patients after sudden cardiac death. Their combined role has not been well defined. Twenty-three survivors of sudden death underwent revascularization and AICD implantation at an average age of 59 years. The initial arrest was caused by ventricular fibrillation in 15 and ventricular tachycardia in 8. Exercise stress tests, ambulatory ECGs, and electrophysiological monitoring with programmed electrical stimulation were done preoperatively and postoperatively. Follow-up averaged 24 months with a two-year survival of 91%. Eight patients (35%) required AICD resuscitation an average of 8 months postoperatively, and electrophysiological testing did not accurately predict arrhythmia recurrence. The addition of AICD implantation to revascularization substantially improves survival of patients with sudden cardiac death.

Electrocardiographic localization of coronary artery narrowings: studies during myocardial ischemia and infarction in patients with one-vessel disease.

To investigate the accuracy of the 12-lead ECG in localizing the site of coronary artery narrowings, we reviewed abnormal ECGs obtained during myocardial infarction, spontaneous angina or exercise stress testing in 134 patients with angiographically documented one-vessel disease. The presence of Q waves, ST-segment elevation and T-wave inversion in leads I, aVL and V1--V4 were all highly correlated with the presence of left anterior descending coronary artery disease (p less than 0.001), and the same ECG findings in leads II, III and aVF were associated with right (RCA) or circumflex coronary artery (LCx) narrowings (p less than 0.001). In contrast, ST depression alone was not useful in predicting the site of coronary artery narrowing. Q waves correctly identified the location of the coronary disease in 98% of cases, ST elevation in 91%, T-wave inversion in 84%, and ST depression in 60%. No electrocardiographic criteria distinguished RCA from LCx disease, even in patients with a right-dominant circulation. These findings should lead to a better understanding of the value and limitations of the 12-lead ECG in localizing coronary artery disease.

Clinical and arteriographic variables predictive of survival in coronary artery disease.

Survival, subsequent myocardial infarction and current anginal status were determined for 90 nearly consecutive patients who underwent coronary arteriography at the Johns Hopkins Hospital between 1960 and 1967. All patients had at least one coronary arterial narrowing equal to or greater than 70 percent; 78 of 90 patients would be candidates for coronary bypass surgery by present criteria. Twenty-nine of the 78 surgically "suitable" patients died of cardiac causes; 7 of 49 survivors sustained an acute myocardial infarction (mean follow-up period 9.9 years). Patients with a 70 percent or greater narrowing proximal to the first septal branch of the left anterior descending coronary artery had a significantly greater mortality compared with patients with equivalent narrowing distal to the first septal branch or with patients without 70 percent or greater narrowing of the left anterior descending artery. The patients with a 70 percent or greater narrowing of the left anterior descending artery who died were those with a significant narrowing in at least one other major coronary artery. Multivariate stepwise discriminate function analysis of all clinical, electrocardiographic (except stress electrocardiographic) and arteriographic variables identified three independent predictors of mortality: (1) the simultaneous occurrence of a narrowing in left anterior descending and right coronary arteries, (2) prior myocardial infarction; and (3) 70 percent or greater narrowing proximal to the first anterior descending septal branch. When stress electrocardiographic findings were included, a "positive" stress electrocardiographic test was also an independent predictor of mortality.