Abstract
Monolayer transition metal dichalcogenides (TMD) have numerous potential applications in ultrathin electronics and photonics. The exposure of TMD-based devices to light generates ...photo-carriers resulting in an enhanced conductivity, which can be effectively used, e.g., in photodetectors. If the photo-enhanced conductivity persists after removal of the irradiation, the effect is known as persistent photoconductivity (PPC). Here we show that ultraviolet light (λ = 365 nm) exposure induces an extremely long-living giant PPC (GPPC) in monolayer MoS
2
(ML-MoS
2
) field-effect transistors (FET) with a time constant of ~30 days. Furthermore, this effect leads to a large enhancement of the conductivity up to a factor of 10
7
. In contrast to previous studies in which the origin of the PPC was attributed to extrinsic reasons such as trapped charges in the substrate or adsorbates, we show that the GPPC arises mainly from the intrinsic properties of ML-MoS
2
such as lattice defects that induce a large number of localized states in the forbidden gap. This finding is supported by a detailed experimental and theoretical study of the electric transport in TMD based FETs as well as by characterization of ML-MoS
2
with scanning tunneling spectroscopy, high-resolution transmission electron microscopy, and photoluminescence measurements. The obtained results provide a basis for the defect-based engineering of the electronic and optical properties of TMDs for device applications.
•We have applied the incoherent summation approach, the transmission cross-coefficient (TCC) model and the quasi-coherent model in HRTEM image simulations for aberration-corrected low-voltage ...microscopes operating in the range between 40–80 kV.•The quasi-coherent model provides a sufficient approximation not only for simulating the images of weak phase objects, but also for modelling the imaging of high-Z samples in a Cc/Cs-corrected microscope, as long as the samples contain only several atomic layers.•The quasi-coherent model introduces appreciable errors for modelling the imaging of high-Z samples in a Cs-corrected microscope, and the errors become larger when the atomic number or the sample thickness increases, as well as when the accelerating voltage decreases.
Partial coherence of the electron waves leaving the specimen is taken into account in the high-resolution transmission electron microscopy (HRTEM) image simulation by mainly three methods - the incoherent summation approach, the transmission cross-coefficient (TCC) model, and the quasi-coherent model. In the incoherent summation approach, coherent images are calculated for each point in the effective source and summed up incoherently. The TCC is the transfer function of the microscope obtained based on the incoherent summation approach. An analytical form of the TCC can be derived by assuming a Gaussian distribution for the source radiation and for the variation of the focal length caused by the energy spread of the effective source. In the quasi-coherent model, the partial coherence effect is simplified by multiplying the wave function at the diffraction plane with the envelope functions. Envelope functions suppress the contributions to the image contrast from waves which do not propagate along the optical axis. The quasi-coherent model is usually sufficient for the image simulation of weak phase objects. This model is more computationally efficient than both the incoherent summation approach and the TCC model. For the Cs−corrected and Cc/Cs−corrected microscopes operating at 80 kV, we have compared images simulated by using the three models with the experimental images. The comparison shows that the quasi-coherent model also provides a sufficient approximation for the image simulation of high-Z materials if chromatic aberration is corrected and the samples comprise only several atomic layers. In the case of only Cs-correction, the incoherent summation approach or the TCC model needs to be employed for modelling the imaging of high-Z samples even though it is more computationally consuming.
Summary
Background
Child obesity is a growing public health concern. Excess weight in childhood is known to be associated with a high risk of obesity and obesity‐related comorbidities in adulthood.
...Objectives
This study quantifies lifetime excess costs of overweight and obese adults in Germany taking the history of obesity in childhood into account.
Methods
A two‐stage Markov cohort state transition model was developed. At stage 1, the distribution of body mass index (BMI) categories was tracked from childhood (ages 3–17) to adulthood (age 17 and up). Based on these results, it was distinguished whether adults had been normal in weight or overweight/obese as child. At stage 2, age‐specific and lifetime costs from age 18 onwards were simulated in two further Markov cohort models, one for each of the two BMI groups. Model parameter values were obtained from the German Interview and Examination Survey for Children and Adolescents (KiGGS), the German Microcensus 2009 and published literature.
Results
When compared with normal weight adults, lifetime excess costs are higher among adults who had been overweight or obese at any point during childhood. For 18‐year‐old women (men), who have been overweight/obese during their childhood (ages 3–17), undiscounted lifetime excess costs are estimated at €19 479 (€14 524), with 60% (67%) occurring beyond age 60. Discounted (3%) lifetime excess costs are considerably lower, amounting to €4262 for men and €7028 for women.
Conclusions
Because childhood obesity determines healthcare costs occurring in adulthood, interventions preventing the persistence of child obesity and obesity‐related comorbidities during adulthood could have a substantial impact on reducing the burden of the obesity epidemic.
As a result of population aging, the number of persons dependent on long-term care (LTC) is expected to increase considerably in Germany. Information about LTC preferences is important to ...decision-makers in future reforms. Taking into account the preferences of people can lead to a better congruence between desired and utilized LTC services. The aim of this study was to evaluate LTC preferences, their underlying reasons, and the potential to satisfy individual preferences within the German LTC insurance system.
Interviews with 20 LTC (insurance) experts in Germany between July and September 2014 were analyzed using qualitative content analysis methods.
Irrespective of the care setting, people prefer flexible LTC (services), which allow for as much autonomy and independence as possible. Ideally, care is provided by close relatives at the dependent's home. Besides informal homecare, professional care at home is also (becoming increasingly) important, whereas inpatient LTC (nursing home) is rarely preferred over homecare arrangements. To most LTC dependents, interpersonal needs are more important than bodily and professional aspects of care.
While the flexible choices and manifold options to combine services (high degree of person-centeredness) within the German LTC insurance constitute an important basis for the satisfaction of individual preferences, the widespread lack of information about entitlements, costs of services, and corresponding LTC options in the general population (future dependents) substantially hampers long-term care that is in line with preferences.
Background: This study aimed to determine the prevalence of psychiatric morbidity and distress among 189 consecutively recruited cancer patients upon admission to surgical oncology wards, and to ...investigate the recognition of distressed patients by medical staff. Patients and methods: Assessment consisted of a diagnostic psychiatric interview (SCID, DSM-IV), patient-reported distress using a standardised questionnaire (Hospital Anxiety and Depression Scale), and physicians' and nurses' estimates of patients' distress. Twenty-eight per cent of patients were assigned a psychiatric diagnosis, with adjustment disorder predominating. Results: Surgeons accurately recognised marked distress in 77% of patients with a psychiatric disorder and nurses did so in 75%. Because of low specificity, the positive predictive value was only 39% in surgeons and 40% in nurses. However, recognition of distress translated into referral to the psychosocial liaison service for only a minor proportion of distressed patients. Conclusions: Since a remarkable proportion of distressed patients remained unrecognised by the medical staff, only systematic screening of patients upon admission allows timely support to those who are most in need.
Dose-saving techniques in neck CT cause increased image noise that can be counteracted by iterative reconstruction. Our aim was to evaluate the image quality of advanced modeled iterative ...reconstruction (ADMIRE) in contrast-enhanced low-tube-voltage neck CT.
Sixty-one patients underwent 90-kV(peak) neck CT by using third-generation 192-section dual-source CT. Image series were reconstructed with standard filtered back-projection and ADMIRE strength levels 1, 3, and 5. Attenuation and noise of the sternocleidomastoid muscle, internal jugular vein, submandibular gland, tongue, subscapularis muscle, and cervical fat were measured. Signal-to-noise and contrast-to-noise ratios were calculated. Two radiologists assessed image noise, image contrast, delineation of smaller structures, and overall diagnostic acceptability. Interobserver agreement was calculated.
Image noise was significantly reduced by using ADMIRE compared with filtered back-projection with the lowest noise observed in ADMIRE 5 (filtered back-projection, 9.4 ± 2.4 Hounsfield units HU; ADMIRE 1, 8.3 ± 2.8 HU; ADMIRE 3, 6.7 ± 2.0 HU; ADMIRE 5, 5.4 ± 1.7 HU; all, P < .001). Sternocleidomastoid SNR and internal jugular vein-sternocleidomastoid contrast-to-noise ratios were significantly higher for ADMIRE with the best results in ADMIRE 5 (all, P < .001). Subjective image quality and image contrast of ADMIRE 3 and 5 were consistently rated better than those for filtered back-projection and ADMIRE 1 (all, P < .001). Image noise was rated highest for ADMIRE 5 (all, P < .005). Delineation of smaller structures was voted higher in all ADMIRE strength levels compared with filtered back-projection (P < .001). Global interobserver agreement was good (0.75).
Contrast-enhanced 90-kVp neck CT is feasible, and ADMIRE 5 shows superior objective image quality compared with filtered back-projection. ADMIRE 3 and 5 show the best subjective image quality.
Abstract Aim To evaluate local control for long-term prognosis in retroperitoneal soft-tissue sarcoma (primary tumors (PT) and local recurrence (LR)). Methods A total of 110 patients underwent ...surgery between 1988 and 2002. Prospectively gathered clinicopathological data were analyzed. Kaplan–Meier estimations and Cox regression analyses were performed. Results Resectability was 90%, being comparable for PT ( n = 71) and LR ( n = 39). Morbidity, mortality, blood loss, and operation time did not differ for PT or LR (24% vs. 31%, p = 0.41; 7.0% vs. 5.1%, p = 1.0; 1000 ml vs. 1500 ml, p = 0.17; 240 min vs. 255 min, p = 0.13). Hospitalization was comparable in both groups (median, 12 days (PT) and 13 days (LR)). Follow-up was 89 months (median, IQR 37–112 months). Local 3- and 5-year control rates after complete resection of PT were 66% and 59% (19% and 9% for LR, p < 0.001). The mean number of operations were 1.4 for PT and 2.4 for LR ( p = 0.0047). The 5-year survival rates after complete resection were 51% for PT and 43% for LR ( p = 0.39 ) . The 5-year survival rates were 65%, 4%, and 0% for complete resection, incomplete resection, and exploration, respectively ( p < 0.001). Multivariate analysis showed high-grade and blood loss with a poor prognosis. Conclusions Comparable resectability rates and perioperative outcome were observed for surgery of PT and LR. Consequent reoperation leads to respectable long-term survival rates after resection of LR. The prognosis in retroperitoneal sarcomas varies significantly according to resectability, grade and blood loss.
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