Absence of Quantum-Confined Stark Effect in GaN Quantum Disks Embedded in (Al,Ga)N Nanowires Grown by Molecular Beam Epitaxy.

Several of the key issues of planar (Al,Ga)N-based deep-ultraviolet light-emitting diodes could potentially be overcome by utilizing nanowire heterostructures, exhibiting high structural perfection, and improved light extraction. Here, we study the spontaneous emission of GaN/(Al,Ga)N nanowire ensembles grown on Si(111) by plasma-assisted molecular beam epitaxy. The nanowires contain single GaN quantum disks embedded in long (Al,Ga)N nanowire segments essential for efficient light extraction. These quantum disks are found to exhibit intense light emission at unexpectedly high energies, namely, significantly above the GaN bandgap, and almost independent of the disk thickness. An in-depth investigation of the actual structure and composition of the nanowires reveals a spontaneously formed Al gradient both along and across the nanowire, resulting in a complex core/shell structure with an Al-deficient core and an Al-rich shell with continuously varying Al content along the entire length of the (Al,Ga)N segment. This compositional change along the nanowire growth axis induces a polarization doping of the shell that results in a degenerate electron gas in the disk, thus screening the built-in electric fields. The high carrier density not only results in the unexpectedly high transition energies but also in radiative lifetimes depending only weakly on temperature, leading to a comparatively high internal quantum efficiency of the GaN quantum disks up to room temperature.

[Screening for cancer]. / Screening für Krebserkrankungen.

A low birth rate in addition to an increasing life expectancy within the context of an aging population characterize the current demographic situation in Germany. Cancer is primarily a disease of old age and the frequency increases with an expanding older population. In 2013, cancer was the second most common cause of death in Germany. With the aid of screening examinations cancer should be detected in the early stages so that suitable therapeutic measures can be initiated. In Germany, screening is currently offered for breast, cervical, colorectal, skin and prostate cancer and is covered by the statutory health insurance. Mammography screening is the only organized screening program in Germany. Eligible women are regularly invited to attend this program, which is not the case for the other types of cancer screening. In accordance with the Cancer Screening and Registry Act (KFRG) of 2013, colorectal and cervical cancer screening will also be implemented as organized screening programs in the future. As is the case in the mammography screening program, those eligible to participate will receive an invitation letter and the new programs are to be continually monitored, documented and evaluated.

Multiple state transport deduced by weak antilocalization and electron-electron interaction effects in Sb(x)Te(1-x) layers.

Quantum corrections to the conductivity due to the weak antilocalization (WAL) and electron-electron interaction (EEI) effects are investigated in Sb-Te layers to evaluate the number of independent conduction channels in the topological insulator system. We separate the two contributions in the logarithmic temperature dependence of conductivity relying on their distinct response to a magnetic field. For the WAL effect, the amplitude parameter α being -1 observed in magnetoconductivity is confirmed. The magnitude of the EEI contribution is too large to be produced by one transport channel. The mixing between the surface and bulk states is thus indicated to be weak in the Sb-Te system. In addition, the disorder scattering appears to be less influential for the EEI effect than for the WAL effect.

Concurrent hyperfractionated accelerated radiotherapy with 5-FU and once weekly cisplatin in locally advanced head and neck cancer. The 10-year results of a prospective phase II trial.

PURPOSE: In this study, the acute toxicity and long-term outcome of a hyperfractionated accelerated chemoradiation regimen with cisplatin/5-fluorouracil (5-FU) in patients with locally advanced squamous cell carcinomas of head and neck were evaluated. PATIENTS AND METHODS: From 2000-2002, 38 patients with stage III (5.3 %) and stage IV (94.7 %) head and neck cancer were enrolled in a phase II study. Patients received hyperfractionated-accelerated radiotherapy with 72 Gy in 15 fractions of 2 Gy followed by 1.4 Gy twice daily with concurrent, continuous infusion 5-FU of 600 mg/m(2) on days 1-5 and 6 cycles of weekly cisplatin (30 mg/m(2)). Acute toxicities (CTCAEv2.0), locoregional control (LRC), metastases-free (MFS), and overall survival (OS) were analyzed and exploratively compared with the ARO 95-06 trial. RESULTS: Median follow-up was 11.4 years (95 % CI 8.6-14.2) and mean dose 71.6 Gy. Of the patients, 82 % had 6 (n = 15) or 5 (n = 16) cycles of cisplatin, 5 and 2 patients received 4 and 3 cycles, respectively. Grade 3 anemia, leukopenia, and thrombocytopenia were observed in 15.8, 15.8, and 2.6 %, respectively. Grade 3 mucositis in 50 %, grade 3 and 4 dysphagia in 55 and 13 %. The 2-, 5-, and 10-year LRC was 65, 53.6, and 48.2 %, the MFS was 77.5, 66.7, and 57.2 % and the OS 59.6, 29.2, and 15 %, respectively. CONCLUSION: Chemoradiation with 5-FU and cisplatin seems feasible and superior in terms of LRC and OS to the ARO 95-06C-HART arm at 2 years. However, this did not persist at the 5- and 10-year follow-ups.

Transport properties in a Sb-Te binary topological-insulator system.

Sb-Te layers having various compositions between Sb2Te3 and Sb2Te are grown using molecular beam epitaxy. The structural and electrical properties of the layers change gradually with composition but exhibit a discontinuity involving a bistability. The holes in the layers are generated by Sb bilayers intercalated between Sb2Te3 quintuple layers and their mobility is governed by the scattering from the parent acceptors. Magnetoresistance for compositions around SbTe is linear, for which the reduction of the parabolic component due to low mobility is crucial. Density functional calculations predict Sb2Te3 and SbTe to be topological insulators (TIs) resembling Bi2Se3 and Bi2Te3, respectively. The prefactor of the weak antilocalization effect is α =- 1 regardless of the composition. The Sb-Te system is thus a family of TIs possessing undisturbed surface states for which the location of the Dirac point with respect to the bulk band gap is adjustable.

[Bariatric surgery - significance, risks, long term consequences]. / Adipositaschirurgie- Stellenwert, Risiken und Folgen.

In recent years the number of bariatric surgery has markedly increased in industrial nations. Surgery provides a more rapid decrease of body weight than conservative approach. However a long term conservative follow up therapy is mandatory to stabilize reduced weight. Due to increasing knowledge from long term follow up of surgically treated obese patients there is a growing body of evidence that frequently there is necessity of reoperations and of substitution both of trace elementsand of minerals or vitamins due to their hampered enteral resorption. Additionally therapy of surgery induced endocrine alterations not seldom is necessary.These insights are of outstanding importance because meanwhile an enlargement of the indications for bariatric surgery as a therapeutic option for metabolic disorders is being discussed. This review refers to the recent internationally published papers concerning consequences of bariatric surgery.

[Therapy for obesity--conservative and/or surgical?]. / Adipositastherapie--konservativ und/oder chirurgisch?

On comparing surgical and conservative approaches in therapy for obesity it is accepted that there is a more rapid decline in body weight after surgery than by conservative measures. In contrast to widespread convictions, it has been shown that even in extreme obesity (BMI>60 kg/m²) both a meaningful and a long-lasting reduction of body weight is possible by conservative approach. There is an increasing body of evidence that bariatric surgery, especially malabsorptive and combined forms, causes endocrine disturbances and both vitamin and micronutrient deficiencies. Furthermore, alterations in drug pharmacokinetics are possible. Even bariatric surgeons have stated that surgery neither removes the chronic disease obesity nor is its final therapy.

Current path in light emitting diodes based on nanowire ensembles.

Light emitting diodes (LEDs) have been fabricated using ensembles of free-standing (In, Ga)N/GaN nanowires (NWs) grown on Si substrates in the self-induced growth mode by molecular beam epitaxy. Electron-beam-induced current analysis, cathodoluminescence as well as biased µ-photoluminescence spectroscopy, transmission electron microscopy, and electrical measurements indicate that the electroluminescence of such LEDs is governed by the differences in the individual current densities of the single-NW LEDs operated in parallel, i.e. by the inhomogeneity of the current path in the ensemble LED. In addition, the optoelectronic characterization leads to the conclusion that these NWs exhibit N-polarity and that the (In, Ga)N quantum well states in the NWs are subject to a non-vanishing quantum confined Stark effect.

[Are there social inequalities in the utilisation of oncological rehabilitation by breast cancer patients?]. / Gibt es soziale Ungleichheiten in der Inanspruchnahme der onkologischen Rehabilitation bei Mammakarzinompatientinnen?

GOAL: Using data from a sample of breast cancer patients it was examined whether the utilisation of inpatient rehabilitation after breast cancer surgery within one year of primary therapy is unequally distributed. Furthermore, it was considered which reasons are associated with the omission of rehabilitation. MATERIAL AND METHODS: Subjects were women after primary manifestation of breast cancer (stages: T(1)-T(3); N(0)-N(2); M(0)) aged 25-70 years. The data were collected as part of an ongoing prospective study on the role of social factors in the long-term course of breast cancer. Patients were interviewed immediately after primary surgery and a second time 1 year later. Interviews were performed by specially trained interviewers using semi-structured schedules. 3 gynaecological clinics in Hannover were involved. Logistic regression models were used for performing the main analyses. RESULTS: The data of 238 patients were used; 150 (63.3%) of them went to inpatient rehabilitation. Women with 12/13 years of school education were less likely to go to a rehabilitation clinic than women with lower qualifications; no social gradients in terms of occupational position emerged. A strong predictor for rehabilitation was chemotherapy, and in employed women radiotherapy was associated with lower utilisation. The reasons for not going to rehabilitation appear to be rather personal. They were motivated by patients' avoidance of being faced with cancer, and by the desire to take up the every day life that was interrupted by disease. These reasons are not socially patterned. CONCLUSION: We found no evidence for social barriers for utilising inpatient rehabilitation, but rather that medical and particularly individual reasons apply.

Influence of hepatocyte growth factor on autologous osteochondral transplants in an animal model.

PURPOSE: Several studies have investigated the influence of different growth factors on hyaline cartilage regeneration. In a rabbit model, hepatocyte growth factor (HGF) was proven to increase the amount of hyaline-like chondrocytes in a mixed fibro-cartilaginous regenerate of small defects. The aim of the current study was to evaluate whether intra-articular administration of HGF influences the ingrowth of osteochondral grafts in a sheep model. TYPE OF STUDY: Animal experiment. METHODS: Both knee joints of eight sheep were opened surgically and osteochondral grafts were harvested and simultaneously transplanted to the opposite condyle of the same joint. The sheep were divided into two groups of four sheep, resulting in 16 grafts per group. In one group, HGF was administered by bilateral intra-articular injections given three times a week for 4 weeks. The control group received isotonic sodium chloride injections. The animals were killed after 3 months. RESULTS: Histological evaluation showed a complete ingrowth of the osseous part of the osteochondral grafts. A healing or ingrowth at the level of the cartilage could not be observed. Histological evaluation of the transplanted grafts according to the modified Mankin score revealed less degeneration in the cartilage of the HGF group, as compared to the control group. In the HGF group, less cloning of chondrocytes and less irregularities of the articular surface were observed. Importantly, no deleterious effects, such as osteophyte formation, cartilage thickening or synovial proliferation, were found. CONCLUSION: HGF positively influenced the cellularity of the transplanted osteochondral graft, but could not diminish the fissures in the marginal zone of the grafts. CLINICAL RELEVANCE: Marginal zone fissures and degeneration in the absence of HGF may undermine long-term results of autologous osteochondral grafts.

[Synchronising school entry health examinations in Lower-Saxony, Germany]. / Synchronisierung von Schuleingangsuntersuchungen in Niedersachsen.

BACKGROUND: In the German federal state of Lower-Saxony the districts are responsible for conducting school entry health examinations. There exist two different standard protocols for diagnosis and documentation, denoted as Weser-Ems (WE) and SOPHIA. In order to analyse and improve the comparability between these two protocols, a working group was established in 2006. One of the objectives was to adjust the protocols in such a way that in the future the collected data will allow for joint health reporting. METHODS: Each variable was discussed individually by the working group, and if diagnosis or documentation differed between the two protocols, specific modifications were proposed. For certain variables external expert opinions were obtained. For those variables that had to be revised quite generally, specific sub-working groups were established. As prerequisite for implementation, the recommendations of the working group had to be accepted by the user groups through majority votes. RESULTS: Of 88 (WE) or, respectively, 66 (SOPHIA) variables, 39 (WE) or, respectively, 34 variables initially fulfilled the requirements for a joint analysis. As a result of the working group, for more than 20 other variables the requirements for a joint analysis could be achieved. As soon as the sub-working groups have completed their work, also the issues of physical coordination, cognitive abilities and psychological health will be available for joint analysis. DISCUSSION: The synchronisation of school entry health examinations in Lower-Saxony is an example of how different protocols of diagnosis and documentation can be adapted to each other to enable joint data analysis without loosing their individual characteristics.

[How often is bronchopneumonia overlooked as the cause of death in intensive care unit patients?]. / Wie häufig wird die Bronchopneumonie als Todesursache bei Intensivpatienten übersehen?

BACKGROUND: This study addresses the issue of analyzing the relationship between pre-mortem diagnoses and post-mortem findings in an intensive care unit (ICU). MATERIALS AND METHODS: Investigating a total of 1,205 autopsy cases, pre-mortem and post-mortem diagnoses were retrospectively evaluated and compared statistically by means of established categories (i.e."complete, partial, or lacking concordance" and"clinically suspected diagnosis"). RESULTS: When comparing clinical diagnoses and autopsy findings in terms of bronchopneumonia, concordance was recorded in only 21.15% of the cases investigated. CONCLUSION: In multimorbid ICU patients, bronchopneumonia frequently fails to be clinically recognized since clinical parameters commonly used for monitoring appear to be modified due to therapeutical interventions, and thus are inappropriate to reflect the complete histomorphological equivalent of the disease. This study also emphasizes the importance of autopsy which represents a sensitive means for professional medical quality assurance, and again establishes the necessity for strengthening the request for autopsy, which is currently characterized by an unfavourable decline.

Al compositional inhomogeneity of AlGaN epilayer with a high Al composition grown by metal-organic chemical vapour deposition.

The Al compositional distribution of AlGaN is investigated by cathodoluminescence (CL). Monochromatic CL images and CL spectra reveal a lateral Al compositional inhomogeneity, which corresponds to surface hexagonal patterns. Cross-sectional CL images show a relatively uniform Al compositional distribution in the growth direction, indicating columnar growth mode of AlGaN films. In addition, a thin AlGaN layer with lower Al composition is grown on top of the buffer AlN layer near the bottom of the AlGaN epilayer because of the larger lateral mobility of Ga adatoms on the growth surface and their accumulation at the grain boundaries.

[Contributions of the epidemiological cancer registries to the evaluation of mammography screening in Germany]. / Beiträge bevölkerungsbezogener Krebsregister zur Evaluation des bundesweiten Mammographie-Screenings. Erste Ergebnisse zu Brustkrebsinzidenz und T-Stadienverteilung von Teilnehmerinnen des Mammographie-Screenings Weser-Ems (MSWE) im bevölkerungsbezogenen Vergleich.

INTRODUCTION: Before the country-wide introduction of mammography screening, testing of the organised screening took place in Weser-Ems, Bremen and Wiesbaden. Important quality assurance parameters (carcinomas detected during checkup intervals, tumour stage distribution, breast cancer incidence rate, breast cancer mortality rate) are to be evaluated via epidemiological cancer registries. For the model region Weser-Ems (MSWE) the record linkage with the epidemiological cancer registry Lower Saxony (EKN) was successfully accomplished. The technical realisation and first comparison analyses for the development of breast cancer incidence and of tumour size are reported. MATERIAL AND METHODS: The target population of the MSWE was 22,600 women aged 50-69 years. They were invited since May 2002 to mammography screening with a screening interval of two years. The record linkage of 12,913 women who participated until February 2004 in the MSWE, was realised by the use of the control number system of the epidemiological cancer registries. The observation time was between 6 and 25 month (median: 15 month). Reference population for comparison analyses were all women between 50 and 69 years of the remaining governmental district Weser-Ems (255,000 women). RESULTS: In the first record linkage 96 screening-cases (ICD-10 C50 + D05) could be identified. Additionally six interval cancers were determined (time between screening and diagnosis in months: median 5.5; mean 7.7). The breast cancer incidence increased in the MSWE area and in the control-area, the rise in the MSWE area being higher. The increase was especially observed with the small tumours. Women with breast cancer diagnosed by screening: 19.8% in-situ-cancer and 18.8% very small tumours < = 10 mm. In the control area Weser-Ems this rate with 5.6% in-situ-cancer and 14.5% very small tumours, was relatively high, indicating the spread of opportunistic mammographies in absence of organised screening. CONCLUSION: First effects of mammography screening can be evaluated early by comparison between screening data and the data of population-based cancer registries. Using the control number system of the epidemiological cancer registries and comparison by pseudonyms the evaluation of quality assurance parameters of the MSWE can be realised in compliance with the data security law. The feedback of cancers, detected during checkup intervals is not covered by the cancer registry law. For the implementation of the guidelines for early recognition cancer legal adjustments will be necessary. This concept can be easily adapted to other screening programme.

Hyaline cartilage degenerates after autologous osteochondral transplantation.

OBJECTIVES: Autologous osteochondral grafting is a well-established clinical procedure to treat focal cartilage defects in patients, although basic research on this topic remains sparse. The aim of the current study was to evaluate (1) histological changes of transplanted hyaline cartilage of osteochondral grafts and (2) the tissue that connects the transplanted cartilage with the adjacent cartilage in a sheep model. METHOD: Both knee joints of four sheep were opened surgically and osteochondral grafts were harvested and simultaneously transplanted to the contralateral femoral condyle. The animals were sacrificed after three months and the received knee joints were evaluated histologically. RESULTS: Histological evaluation showed a complete ingrowth of the osseous part of the osteochondral grafts. A healing or ingrowth at the level of the cartilage could not be observed. Histological evaluation of the transplanted grafts according to Mankin revealed significantly more and more severe signs of degeneration than the adjacent cartilage, such as cloning of chondrocytes and irregularities of the articular surface. CONCLUSION: We found no connecting tissue between the transplanted and the adjacent cartilage and histological signs of degeneration of the transplanted hyaline cartilage. In the light of these findings, long-term results of autologous osteochondral grafts in human beings have to be followed critically.

Vascular anastomosing by gluing--an experimental study.

BACKGROUND: Performing anastomoses by stitching is very time-consuming. We therefore looked for an alternative technique and used a relatively new surgical adhesive. METHODS: Ten anastomoses between the aorta and a prosthesis were performed on five pigs (Deutsche Landrasse) using surgical glue (BioGlue). The proximal anastomoses between the abdominal aorta and the prostheses were performed end-to-side just below the renal arteries, the distal anastomoses in an end-to-end fashion just above the iliac bifurcation. The aorta between the anastomoses was ligated and resected. The animals were sacrificed between one week and up to four months after operation and anastomoses were analysed by angiography, CT angiography, angioscopy, and histology. RESULTS: Angiography and CT angiography revealed that all anastomoses were patent. No aneurysms were found at the site of anastomoses. No haematomas were detected. Angioscopy revealed well-healed connections between the original aorta and the prosthesis. CONCLUSIONS: We could demonstrate that anastomoses between the aorta and a prosthesis can be performed safely using a surgical adhesive. Further investigations of these anastomoses, especially over the long term, using calcified aortas, are necessary.