Ballistic InSb Nanowires and Networks via Metal-Sown Selective Area Growth

Selective area growth is a promising technique to realize semiconductor-superconductor hybrid nanowire networks, potentially hosting topologically protected Majorana-based qubits. In some cases, however, such as the molecular beam epitaxy of InSb on InP or GaAs substrates, nucleation and selective growth conditions do not necessarily overlap. To overcome this challenge, we propose a metal-sown selective area growth (MS SAG) technique, which allows decoupling selective deposition and nucleation growth conditions by temporarily isolating these stages. It consists of three steps: (i) selective deposition of In droplets only inside the mask openings at relatively high temperatures favoring selectivity, (ii) nucleation of InSb under Sb flux from In droplets, which act as a reservoir of group III adatoms, done at relatively low temperatures, favoring nucleation of InSb, and (iii) homoepitaxy of InSb on top of the formed nucleation layer under a simultaneous supply of In and Sb fluxes at conditions favoring selectivity and high crystal quality. We demonstrate that complex InSb nanowire networks of high crystal and electrical quality can be achieved this way. We extract mobility values of 10※000-25※000 cm V s consistently from field-effect and Hall mobility measurements across single nanowire segments as well as wires with junctions. Moreover, we demonstrate ballistic transport in a 440 nm long channel in a single nanowire under a magnetic field below 1 T. We also extract a phase-coherent length of ∼8 μm at 50 mK in mesoscopic rings

Mortality and Its Determinants in Late-Life Schizophrenia: A 5-Year Prospective Study in a Dutch Catchment Area

It is uncertain if the raised mortality in schizophrenia persists in later life. Register-based studies suggest that excess mortality continues, although at a lower level than in younger age groups. However, prospective follow-up studies of older schizophrenia samples are lacking. A cohort of 157 older patients (mean age at study entry: 68 years) diagnosed with schizophrenia or schizoaffective disorder in a psychiatric catchment area in Amsterdam, the Netherlands was studied. Standardized mortality rate (SMR) was estimated at a 5-year follow-up, in referral to the same age group in the general catchment area population. The impact on survival time of a range of independent demographic and clinical predictors was evaluated. The cohort had an all-cause SMR of 1.89 (95% CI: 1.28-2.70). SMR was higher in men (2.60; 95% CI: 1.42-4.37) than in women (1.78; 95% CI: 1.02-2.90). All deaths were from natural causes. Reduced survival was associated with higher age (HR: 1.10; 95% CI: 1.05-1.16), male gender (HR: 3.94; 95% CI: 1.87-8.31), and having had one or more compulsory admissions in the past (HR: 2.61; 95% CI: 1.46-4.68). In contrast, no mortality associations were found with diagnosis (schizophrenia versus schizoaffective disorder), age at onset of the disorder, or current prescription of antipsychotics. The excess mortality in schizophrenia continues into late life, affecting men more often than women. Given the poor insight into the underlying mechanisms of this disquieting finding, there is a need to identify modifiable clinical and social risk factor

Social Functioning Among Older Community-Dwelling Patients With Schizophrenia: A Review

Social dysfunction is a hallmark of schizophrenia and a major constituent of its burden of disease. There is a need for more data on social functioning of older schizophrenic patients, because their numbers are rapidly growing and most are residing within the community. This article reviews existing evidence on social functioning in community-dwelling schizophrenic patients older than 55 years, focusing on social roles, social support, and social skills. Thirty-six publications proved fit for inclusion in the review. Studies from outside the United States were underrepresented. The available data suggest that the majority of older schizophrenic patients are well behind their healthy age-peers with respect to various aspects of social functioning. At the same time, a considerable heterogeneity among patients can be found. Cognitive abilities feature as a factor of major impact on social functioning, outweighing clinical symptoms. When evaluating social functioning both objective and subjective appraisals should be taken into account, because they may highlight different aspects of social functioning. Social support, impact of gender, and specific characteristics of older-old patients figure among areas that should be given priority in future research of social functioning in late life schizophrenia. (Am J Geriatr Psychiatry 2010; 18: 862-878

Schizophrenia Spectrum Disorders in Later Life: Prevalence and Distribution of Age at Onset and Sex in a Dutch Catchment Area

Objectives: The prevalence of schizophrenia in later life is affected by both outflow of early onset patients, due to recovery and excess mortality, and inflow of patients with a later age at onset, making it likely that characteristics of older patients differ markedly from younger patients. We assessed the prevalence of schizophrenia and spectrum disorders and their distribution according to age at onset and sex in an elderly population. Design: Case register study. Setting and Participants: All patients age 60 years and older, in contact with the Mental Health Organization in a psychiatric catchment area in Amsterdam (the Netherlands), diagnosed with schizophrenia, schizoaffective disorder, or delusional disorder. Measurements: One-year prevalence estimates, including rates according to age group, age at onset, and sex. In addition, we determined the effect of using different criteria for age at onset. Results: The one-year prevalence of all disorders was 0.71%, subdivided in 0.55% for schizophrenia, 0.14% for schizoaffective disorder, and 0.03% for delusional disorder. The one-year prevalence of early-onset schizophrenia was 0.35%, of late-onset schizophrenia 0.14%, and of very-late-onset schizophrenia-like psychosis 0.05%. Variation of onset criterion affected the proportion of early-onset versus late-onset schizophrenia patients stronger in women than in men. Women outnumbered men markedly in the prevalence estimates for most diagnostic subgroups, including early-onset schizophrenia. Conclusions: We found the prevalence of schizophrenia among older persons to be well within the range reported for younger populations. The considerable proportion with a later age at onset and the strong female preponderance are distinguishing characteristics of older patients with clinical implications. (Am J Geriatr Psychiatry 2012; 20: 18-28

A comparison of depressive symptom profiles between current major depressive disorder and schizophrenia spectrum disorder

Introduction: Depressive symptoms are highly prevalent and clinically relevant in schizophrenia spectrum disorder (SSD) patients. So far, little is known about to what extent the depressive symptom profile in SSD is comparable to that seen in major depressive disorder (MDD). Methods: Data were derived from the Genetic Risk and Outcome of Psychosis study (GROUP) and the Netherlands Study of Depression and Anxiety (NESDA). We examined differences in severity of depressive symptom profiles and distribution of mood/cognition and somatic/vegetative depressive symptoms using the Quick Inventory of Depressive Symptomatology - Self Report (QIDS-SR) within SSD patients (n = 449), MDD patients (n = 816) and healthy controls (n = 417), aged 18 to 50. Within SSD, associations between depression severity and clinical and demographic data were examined. Results: 60.4% of SSD patients showed substantial depressive symptomatology (QIDS-SR >= 6). The difference in mood/cognition symptoms between SSD and MDD was larger (higher symptoms in MDD, effect size = 1.13), than the differences in somatic/vegetative symptoms (effect size 0.74). In patients with SSD, multivariable regression analyses showed that lower social functioning, male gender, use of benzodiazepine and more severe positive symptoms were associated with higher overall depressive symptomatology. The use of antipsychotics or anti-depressants was associated with more somatic/vegetative symptoms. Conclusion: More than half of SSD patients have considerable depressive symptomatology, with a relative preponderance of somatic/vegetative symptoms compared to the profile seen in MDD. Future research could explore whether depressive symptom profile in SSD may also be associated with biological dysregulations like in MDD

Ballistic InSb Nanowires and Networks via Metal-Sown Selective Area Growth

Selective area growth is a promising technique to realize semiconductor-superconductor hybrid nanowire networks, potentially hosting topologically protected Majorana-based qubits. In some cases, however, such as the molecular beam epitaxy of InSb on InP or GaAs substrates, nucleation and selective growth conditions do not necessarily overlap. To overcome this challenge, we propose a metal-sown selective area growth (MS SAG) technique, which allows decoupling selective deposition and nucleation growth conditions by temporarily isolating these stages. It consists of three steps: (i) selective deposition of In droplets only inside the mask openings at relatively high temperatures favoring selectivity, (ii) nucleation of InSb under Sb flux from In droplets, which act as a reservoir of group III adatoms, done at relatively low temperatures, favoring nucleation of InSb, and (iii) homoepitaxy of InSb on top of the formed nucleation layer under a simultaneous supply of In and Sb fluxes at conditions favoring selectivity and high crystal quality. We demonstrate that complex InSb nanowire networks of high crystal and electrical quality can be achieved this way. We extract mobility values of 10※000-25※000 cm V s consistently from field-effect and Hall mobility measurements across single nanowire segments as well as wires with junctions. Moreover, we demonstrate ballistic transport in a 440 nm long channel in a single nanowire under a magnetic field below 1 T. We also extract a phase-coherent length of ∼8 μm at 50 mK in mesoscopic rings

InAs-Al Hybrid Devices Passing the Topological Gap Protocol

We present measurements and simulations of semiconductor-superconductor heterostructure devices that are consistent with the observation of topological superconductivity and Majorana zero modes. The devices are fabricated from high-mobility two-dimensional electron gases in which quasi-one-dimensional wires are defined by electrostatic gates. These devices enable measurements of local and non-local transport properties and have been optimized via extensive simulations for robustness against non-uniformity and disorder. Our main result is that several devices, fabricated according to the design's engineering specifications, have passed the topological gap protocol defined in Pikulin {\it et al.}\ [arXiv:2103.12217]. This protocol is a stringent test composed of a sequence of three-terminal local and non-local transport measurements performed while varying the magnetic field, semiconductor electron density, and junction transparencies. Passing the protocol indicates a high probability of detection of a topological phase hosting Majorana zero modes. Our experimental results are consistent with a quantum phase transition into a topological superconducting phase that extends over several hundred millitesla in magnetic field and several millivolts in gate voltage, corresponding to approximately one hundred micro-electron-volts in Zeeman energy and chemical potential in the semiconducting wire. These regions feature a closing and re-opening of the bulk gap, with simultaneous zero-bias conductance peaks at {\it both} ends of the devices that withstand changes in the junction transparencies. The measured maximum topological gaps in our devices are 20-$30\,\mu$eV. This demonstration is a prerequisite for experiments involving fusion and braiding of Majorana zero modes.Comment: Fixed typos. Fig. 3 is now readable by Adobe Reade