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Multiple-choice questions (MCQs) provide useful information about correct and incorrect answers, but they do not offer information about students' confidence.Ninety and another 81 medical students participated each in a curricular neurology multiple-choice exam and indicated their confidence for every single MCQ. Each MCQ had a defined level of potential clinical impact on patient safety (uncritical, risky, harmful). Our first objective was to detect informed (IF), guessed (GU), misinformed (MI), and uninformed (UI) answers. Further, we evaluated whether there were significant differences for confidence at correct and incorrect answers. Then, we explored if clinical impact had a significant influence on students' confidence.There were 1818 IF, 635 GU, 71 MI, and 176 UI answers in exam I and 1453 IF, 613 GU, 92 MI, and 191 UI answers in exam II. Students' confidence was significantly higher for correct than for incorrect answers at both exams (p 0.001). For exam I, students' confidence was significantly higher for incorrect harmful than for incorrect risky classified MCQs (p = 0.01). At exam II, students' confidence was significantly higher for incorrect harmful than for incorrect benign (p 0.01) and significantly higher for correct benign than for correct harmful categorized MCQs (p = 0.01).We were pleased to see that there were more informed than guessed, more uninformed than misinformed answers and higher students' confidence for correct than for incorrect answers. Our expectation that students state higher confidence in correct and harmful and lower confidence in incorrect and harmful MCQs could not be confirmed.

Hintergrund Medikamentöse Therapiestrategien zur Behandlung der rheumatoiden Arthritis sind entscheidend für den Langzeitverlauf. Sie dienen dem Ziel, durch frühe und konsequente Unterdrückung der Entzündung Gelenkzerstörung zu verhindern und damit die Funktion zu erhalten. Ziel der Arbeit Erarbeitung eines Konsenses für evidenzbasierte Empfehlungen zur Behandlung der rheumatoiden Arthritis mit krankheitsmodifizierenden Medikamenten in Deutschland. Methoden Nach einer systematischen Literatursuche wurde ein strukturierter Konsensprozess durchgeführt. Ergebnisse Sechs übergeordnete Prinzipien und 10 Empfehlungen fassen die Ergebnisse des Konsensprozesses zusammen. Verschiedene Punkte sind gegenüber der Fassung von 2012 neu, so die differenzierte Anpassung des Therapieregimes nach Zeitpunkt und Ausmaß des Ansprechens, das Therapieziel Remission gemessen mithilfe des simplified disease activity index (SDAI) wie auch der potentielle Einsatz zielgerichteter synthetischer DMARDs (tsDMARDs), der JAK-Inhibitoren sowie Empfehlungen zur Deeskalation nach dem Erreichen einer anhaltenden Remission. Wie bisher steht Methotrexat (MTX) im Mittelpunkt der Therapie zu Beginn und als Kombinationspartner im weiteren Verlauf. Die Kombination mehrerer konventioneller synthetischer DMARDs, oder, bei ungünstigen prognostischen Faktoren, der Einsatz von biologischen oder tsDMARDs kommen nach dem Algorithmus bei nicht ausreichendem Ansprechen auf Methotrexat zur Anwendung. Empfehlungen für die Deeskalation der Therapie mit Glukokortikoiden und konsekutiv gegebenenfalls auch DMARDs geben Hilfe für den Umgang mit Patienten, die eine anhaltende Remission erreicht haben. Zusammenfassung Die neue S2-Leitlinie gibt Empfehlungen für die Therapie der RA nach dem Prinzip des ""Treat-to-Target"" (T2T) mit etablierten und neuen krankheitsmodifizierenden Medikamenten (DMARDs), einschließlich der Biologika und JAK-Inhibitoren und macht Vorschläge zur Deeskalation nach Erreichen einer anhaltenden Remission.

All mechanically ventilated patients must be weaned from the ventilator at some stage. According to an International Consensus Conference the criteria for “prolonged weaning” are fulfilled if patients fail at least 3 weaning attempts (i. e. spontaneous breathing trial, SBT) or require more than 7 days of weaning after the first SBT. This occurs in about 15 – 20 % of patients. Because of the growing number of patients requiring prolonged weaning a German guideline on prolonged weaning has been developed. It is an initiative of the German Respiratory Society (Deutsche Gesellschaft fur Pneumologie und Beatmungsmedizin e. V., DGP) in cooperation with other societies (see acknowledgement) engaged in the field chaired by the Association of Scientific and Medical Societies in Germany (Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften, AWMF). This guideline deals with the definition, epidemiology, weaning categories, underlying pathophysiology, therapeutic strategies, the weaning unit, transition to out-of-hospital ventilation and therapeutic recommendations for end of life care. This short version summarises recommendations on prolonged weaning from the German guideline.

Drug hypersensitivity reactions are unpredictable adverse drug reactions. They manifest either within 1–6 h following drug intake (immediate reactions) with mild to life-threatening symptoms of anaphylaxis, or several hours to days later (delayed reactions), primarily as exanthematous eruptions. It is not always possible to detect involvement of the immune system (allergy). Waiving diagnostic tests can result in severe reactions on renewed exposure on the one hand, and to unjustified treatment restrictions on the other. With this guideline, experts from various specialist societies and institutions have formulated recommendations and an algorithm for the diagnosis of allergies. The key principles of diagnosing allergic/hypersensitivity drug reactions are presented. Where possible, the objective is to perform allergy diagnostics within 4 weeks–6 months following the reaction. A clinical classification of symptoms based on the morphology and time course of the reaction is required in order to plan a diagnostic work-up. In the case of typical symptoms of a drug hypersensitivity reaction and unequivocal findings from validated skin and/or laboratory tests, a reaction can be attributed to a trigger with sufficient confidence. However, skin and laboratory tests are often negative or insufficiently reliable. In such cases, controlled provocation testing is required to clarify drug reactions. This method is reliable and safe when attention is paid to indications and contraindications and performed under appropriate medical supervision. The results of the overall assessment are discussed with the patient and documented in an „allergy passport“ in order to ensure targeted avoidance in the future and allow the use of alternative drugs where possible.

Background. Although CSF cytology and MRI are standard methods to diagnose neoplastic meningitis (NM), this complication of neoplastic disease remains difficult to detect. We therefore reevaluated the sensitivity of gadolinium (GD)-enhanced MRI and cerebrospinal-fluid (CSF)-cytology and the relevance of tumor type and CSF cell count.Methods. We retrospectively identified 111 cases of NM diagnosed in our CSF laboratory since 1990 with complete documentation of both MRI and CSF cytology. 37 had haematological and 74 solid neoplasms. CSF cell counts were increased in 74 and normal in 37 patients.Results. In hematological neoplasms, MRI was positive in 49% and CSF cytology in 97%. In solid tumors, the sensitivity of MRI was 80% and of cytology 78%. With normal CSF cell counts, MRI was positive in 59% (50% hematological, 72% solid malignancies) and CSF cytology in 76% (92% in hematological, 68% in solid neoplasms). In cases of elevated cell counts, the sensitivity of MRI was 72% (50% for hematological, 83% for solid malignancies) and of CSF cytology 91% (100% for haematological and 85% for solid neoplasms). 91% of cytologically positive cases were diagnosed at first and another 7% at second lumbar puncture. Routine protein analyses had a low sensitivity in detecting NM.Conclusions. The high overall sensitivity of MRI was only confirmed for NM from solid tumors and for elevated CSF cell counts. With normal cell counts and haematological neoplasms, CSF-cytology was superior to MRI. None of the analysed routine CSF proteins had an acceptable sensitivity and specificity in detecting leptomeningeal disease.

Currently, management of antibody deficient patients differs significantly among caregivers. Evidence and consensus based (S3) guidelines for the treatment of primary antibody deficiencies were developed to improve the management of these patients.

Hintergrund: Bei der Polyneuropathie handelt es sich um eine Schadigung mehrerer oder aller peripheren Nerven. Sie kann mit teils qualenden neuropathischen Schmerzen einhergehen und ist fur erhebliche Morbiditat, eine erhohte Mortalitat und Beeintrachtigung der Lebensqualitat verantwortlich. Durch die Polyneuropathie kommt es zudem zu haufigen Sturzen. Die Schmerzbehandlung basiert im Wesentlichen auf Medikamenten. Bei Morbus Parkinson und Ruckenmarksverletzungen konnte die stochastische Resonanztherapie zentral- und periphernervale Interaktionsmechanismen positiv beeinflussen, was mit einer Verbesserung der posturalen Kontrolle einherging. Ziel: Untersuchung des Einflusses der stochastischen Resonanztherapie bei Patienten mit peripherer Neuropathie auf Vibrationsempfinden, Schmerz, statische und dynamische posturale Kontrolle. Methode: Fur die randomisierte klinische Studie wurden 32 Patienten mit Polyneuropathie randomisiert in Experimental- und Kontrollgruppe eingeteilt. Die Experimentalgruppe erhielt uber einen Zeitraum von 8 Wochen 2-mal wochentlich stochastische Resonanztherapie, die Kontrollgruppe eine Wassertherapie. Ergebnisse: Die Schmerzintensitat auf der Visuellen Analogskala verringerte sich in beiden Gruppen: in der Experimentalgruppe um 18,8 mm, in der Kontrollgruppe um 5,06 mm. Die Verbesserungen im Intergruppenvergleich waren nicht signifikant. Das Vibrationsempfinden verbesserte sich im Pra-post-Vergleich ebenfalls. Am Messpunkt des linken Groszehengrundgelenks zeigte sich eine statistisch nicht signifikante Verbesserung des Vibrationsempfindens von 2,13 auf 2,47 (Experimentalgruppe) und von 1,82 auf 2,94 (Kontrollgruppe). Die Verbesserungen waren an allen anderen Messpunkten gleichermasen nicht signifikant. Die statische und dynamische posturale Kontrolle konnte verbessert werden, die Ergebnisse waren jedoch nicht signifikant (p > 0,05). Schlussfolgerungen: Die stochastische Resonanztherapie zeigt bei Patienten mit Polyneuropathie klinisch positive Effekte. Allerdings ist sie bei Patienten mit peripherer Neuropathie einer Wassertherapie nicht uberlegen. Die weitere Untersuchung von Ganzkorpervibrationen beim Krankheitsbild der peripheren Neuropathie ware notwendig, um mehr Wissen uber diesen Sachverhalt zu generieren.

Die Standardisierung der Therapie der Juvenilen Idiopathischen Arthritis (JIA) hat zu einer Verbesserung der Lebensqualitat von Kindern und Jugendlichen mit JIA gefuhrt. Um die Versorgungsqualitat dieser Patienten weiter zu erhohen, ist eine Aktualisierung der bisherigen S2-Leitlinie von 2008 erforderlich. Durch eine neue systematische Literaturanalyse (Stichworter: juvenile idiopathic (rheumatoid) arthritis, therapy; Suchbegrenzungen (Limits) in PUBMED: humans, published in the last 3 years, all child: 0–18 years, clinical trial; Stichtag 15.01.2011) wurden 17 relevante Studien gefunden. Studien zur Diagnostik der JIA, Uveitis, Impfung, Transition wurden ausgeschlossen. Zu moderierten Konsensuskonferenzen wurden Vertreter folgender Fachgesellschaften und Vereinigungen eingeladen: Berufsverband der Kinder- und Jugendarzte (BVKJ), Deutsche Gesellschaft fur Kinder- und Jugendmedizin (DGKJ), Deutsche Gesellschaft fur Rheumatologie (DGRh), Deutsche Ophthalmologische Gesellschaft (DOG), Deutsche Rheuma-Liga Bundesverband, Verein zur Forderung und Unterstutzung rheumatologisch erkrankter Kinder und deren Eltern, Vereinigung fur Kinderorthopadie, Zentraler Verband der Physiotherapeuten und Krankengymnasten (ZVK). Die Konsensuskonferenzen fanden unter > 95% Teilnahme statt. Konsensus-Statements wurden formal per Nominale Gruppentechnik und im Delphiverfahren gewonnen. Zu den Themen medikamentose, symptomatische und chirurgische Therapie wurden aktualisierte Statements im Konsens erarbeitet und nach Kriterien evidenzbasierter Medizin bewertet. Neue, relevante Studien sind in der 2. Auflage der S2-Leitlinie fur die Therapie der JIA berucksichtigt.

The present guideline on allergen-specific immunotherapy (SIT) was established by the German allergy societies in conjunction with other scientific and medical societies (dermatology, ear-nose-throat, pediatrics, lung and airway diseases) and a patient support group according to criteria of the Association of the Scientific Medical Societies in Germany (AWMF). Subcutaneous immunotherapy (SCIT) is a unique causal treatment of IgE-mediated allergic diseases and induces longterm tolerance to the applied allergens due to numerous immunologic effects. Non-modified allergens are used as aqueous or physically coupled (depot) allergen extracts, chemically modified allergens (allergoids) are used as depot extracts for SCIT. Efficacy of SCIT has been demonstrated for pollen and house dust mite allergens in a large number of studies in patients with allergic rhinoconjunctivitis, and for animal dander (cat) and mold allergens (Alternaria, Cladosporium) in few studies. SCIT has been well-studied in intermittent and mild persisting IgE-mediated allergic asthma and is recommended as a therapeutic option besides allergen avoidance and pharmacotherapy. Preventive aspects, particularly reduced development of bronchial asthma and less novel allergic sensitizations, are increasingly considered during the decision for SCIT. In case of systemic reactions due to Hymenoptera (bee, wasp) venom allergy SCIT has excellent efficacy and should be continued for at least 3 - 5 years. An extended, sometimes lifelong SCIT, is necessary in a few patients. SCIT is indicated in patients with IgE-mediated sensitizations and corresponding clinical symptoms to allergens which do not permit allergen avoidance and which are available as suitable extracts. Diagnostic procedures, indication and selection of appropriate allergens for SCIT are made by a physician with certified training or qualified knowledge and skills in allergology. Contraindications have to be considered on an individual basis. Injections of SCIT are administered by a physician experienced in this therapy and who is able to perform emergency treatment in case of an allergic adverse event. Patients information and documentation are mandatory previous to the start of SCIT. Children tolerate SCIT very well and benefit especially from its immuno-modulatory effects. Systemic adverse reactions can occur due to SCIT, being rare in case of complete adherence to safety standards. Most adverse events are mild to moderate and easily treatable. Risk factors for and sequels of unwanted systemic effects can effectively be minimized by training the staff members involved, adhering to safety standards and immediate emergency treatment. Sublingual immunotherapy (SLIT) is an option for adults with allergic rhinoconjunctivitis due to pollen allergens, particularly if SCIT is not suitable. In house dust mite allergy and allergic asthma, SLIT does not substitute SCIT. Due to the present data, SLIT is not recommended for routine use in children and adolescents. A final conclusion on SLIT for children and adolescents is warranted if further study results are available. Various research fields like allergen characterization, routes of application, adjuvants, updosing regimen and preventive aspects demonstrate new developments in SIT being currently examined for clinical efficacy.

General design: Presentation of a new type of a study protocol for evaluation of the effectiveness of an immune modifier (rhG-CSF, filgrastim): prevention of postoperative infectious complications and of sub-optimal recovery from operation in patients with colorectal cancer and increased preoperative risk (ASA 3 and 4). This part describes the design of the randomised, placebo controlled, double-blinded, single-centre study performed at an university hospital (n = 40 patients for each group).¶Objective: The trial design includes the following elements for a prototype protocol:¶ - The study population is restricted to patients with colorectal cancer, including a left sided resection and an increased perioperative risk (ASA 3 and 4).¶ - Patients are allocated by random to the control or treatment group.¶ - The double blinding strategy of the trial is assessed by psychometric indices.¶ - An endpoint construct with quality of life (EORTC QLQ-C30) and a recovery index (modified Mc Peek index) are used as primary endpoints. Qualitative analysis of clinical relevance of the endpoints is performed by both patients and doctors.¶ - Statistical analysis uses an area under the curve (AUC) model for improvement of quality of life on leaving hospital and two and six months after operation. A confirmatory statistical model with quality of life as the first primary endpoint in the hierarchic test procedure is used. Expectations of patients and surgeons and the negative affect are analysed by social psychological scales.¶Conclusion: This study design differs from other trials on preoperative prophylaxis and postoperative recovery, and has been developed to try a new concept and avoid previous failures.¶

In einer Beobachtungsstudie wurden 178 ambulante Patienten mit Verletzungen an der unteren Extremitat, die nach Abwagung ihres individuellen Thromboserisikos anhand einer Checkliste keine medikamentose Thromboembolieprophylaxe erhielten; auf das Auftreten von tiefen Beinvenenthrombosen getestet. Nach Abnahme des Gipsverbands nach durchschnittlich 14,4 (Range 5–48) Tagen erfolgte eine klinische und farbkodierte duplexsonographische Untersuchung. Bei positiven Ausfall einer oder beider Untersuchungen wurde eine Phlebographie durchgefuhrt. Von den 178 untersuchten Studienpatienten entwickelten 2 Patienten eine isolierte Einbundelunterschenkelvenenthrombose (Thromboseinzidenz 1,1%, 95-%-Konfidenzintervall 0–4,4%). Eine Lungenembolie wurde bei keinem Patienten beobachtet. Aufgrund unserer Ergebnisse erscheint eine generelle medikamentose Thromboembolieprophylaxe bei jungen, gesunden Patienten mit einer Verletzung an der unteren Extremitat und einer Ruhigstellung im Gipsverband nicht indiziert.

Die interdisziplinare Leitlinie der Qualitat S3 zur Diagnose und Therapie des hepatozellularen Karzinoms (HCC) ist ein evidenz- und konsensbasiertes Instrument, um die Diagnostik und Therapie des HCC zu verbessern, da die Diagnostik und Therapie des HCC ein auserst diffiziles Vorgehen erfordert. Es ist die Aufgabe der Leitlinie, dem Patienten (mit Verdacht auf HCC oder nachgewiesenem HCC) angemessene, wissenschaftlich begrundete und aktuelle Verfahren in der Diagnostik, Therapie und Rehabilitation anzubieten. Dies gilt sowohl fur die lokal begrenzte oder lokal fortgeschrittene Erkrankung als auch bei Vorliegen eines Rezidivs oder von Fernmetastasen. Die Leitlinie soll neben dem Beitrag fur eine angemessene Gesundheitsversorgung auch die Basis fur eine individuell zugeschnittene, qualitativ hochwertige Therapie bieten. Mit den erklarenden Hintergrundtexten ist es auch nicht spezialisierten, mitbehandelnden Kollegen moglich, den Patienten uber das Vorgehen der Spezialisten, Nebenwirkungen und Ergebnisse gut zu beraten. Mittel- und langfristig sollen so die Morbiditat und Mortalitat von Patienten mit HCC gesenkt und die Lebensqualitat erhoht werden.

We report the optical spectra of C-60 epitaxial films on mica with various thicknesses in the energy range from 1.4 eV to 6 eV, and for temperatures from 13 K to 300 K. The transmittance of toluene, hexane, and heptane solutions of known concentrations has also been studied; a significant shift of the absorption bands in these solvents has been found.

Methods We performed a systematic literature analysis in PubMed (deadline: 15 January 2010, terms “juvenile idiopathic (rheumatoid) arthritis”, “therapy”, limits: “humans”, “published in the last 3 years”, “all child 018 years”, “clinical trial”) and evaluated relevant studies for quality of methodology. A formal consensus process, i.e. Nominal group technique and Delphi method, was conducted at three moderated consensus conferences at Dusseldorf or Krefeld (Germany) on May 9, 2007, August 1, 2007 and January 15, 2010. Conferences were attended by 95% of the representatives who had been nominated by their scientific society or organizations.

It is shown that the free hole concentration for nitrogen doped ZnSe/ZnTe short period superlattices with a given average Te content of 15% can be increased from 1016 to 1019 cm−3 by just increasing the SL period from 2.5 to 4.5 nm. This behavior can be understood in terms of a model that assumes a pinning of the Fermi level at an energetic position that is fixed with respect to the vacuum level. The model can be applied to other II–VI superlattices, and alternative cladding layers for blue laser diodes are proposed that should exhibit significantly higher p‐doping levels than the currently used ZnMgSSe claddings.

ZnMgSe has been suggested as an alternative base material for blue light emitting diodes. For the optimization of such devices the strain state of the active layer is a very important parameter to be considered, since it has recently been considered as the most important factor in the degradation processes of blue diode lasers. In contrast to ZnSe, where CdZnSe quantum wells (QW) are always under compressive strain, the strain status of such QWs in ZnMgSe can be controlled from tensile, for ZnCdSe QW with a low Cd content, to compressive, when the lattice constant of the QW is larger than that of the ZnMgSe barriers. In this paper we present for the first time the photoluminescence (PL) properties of ZnCdSe QW samples with a Cd concentration varying from 0 to about 30%, embedded in ZnMgSe barriers with an Mg content of about 35%.

Using high resolution x‐ray diffraction, it is shown that hot wall epitaxy is an appropriate growth technique in order to obtain perfect monocrystalline C60 thin films with a thickness up to 150 nm. The full width at half‐maximum of rocking curves of the C60 (111) reflex measured on such films is about 210 arcsec. Rocking curves of thicker films exhibit a complex shape, which is interpreted as a result of a change in the growth mode of C60 films exceeding a critical thickness.

The MBE growth of light emitting diodes based on junctions between n‐ZnMgSe and p‐ZnMgSeTe is reported. For optimized compositions of the n‐ and p‐layer, doping levels as high as n=p=2×1018 cm−3 were obtained. The p contacts of these diodes are ohmic, and the voltage needed to achieve a given current density is comparable to that of the best ZnSe based p‐n junctions reported in the literature. The diodes show green electroluminescence up to room temperature.

General design: Presentation of a novel study protocol to evalue the effectiveness of an immune modifier (rhG-CSF, filgrastim): prevention of postoperative infectious complications and sub-optimal recovery from operation in patients with colorectal cancer and increased preoperative risk (ASA 3 and 4). The rationale and hypothesis are presented in this part of the protocol of the randomised, placebo controlled, double-blinded, single-centre study performed at an - university hospital (n = 40 patients for each group). Objective: Part one of this protocol describes the concepts of three major sections of the study: - Definition of optimum and sub-optimal recovery after operation. Recovery, as an outcome, is not a simple univariate endpoint, but a complex construction of mechanistic variables (i. e. death, complications and health status assessed by the surgeon), quality of life expressed by the patient, and finally a weighted outcome judgement by both the patient and the surgeon (true endpoint). Its conventional early assessment within 14-28 days is artificial: longer periods (such as 6 months) are needed for the patient to state: "I am now as well as I was before". Identification of suitable target patients: - the use of biological response modifiers (immune modulators) in addition to traditional prophylaxes (i. e. antibiotics, heparin, volume substitutes) may improve postoperative outcome in appropriate selected patients with reduced host defence and increased immunological stress response, but these have to be defined. Patients classified as ASA 3 and 4 (American Society for Anaesthesiologists) and with colorectal cancer will be studied to prove this hypothesis. Choice of biological response modifier: - Filgrastim has been chosen as an example of a biological response modifier because it was effective in a new study type, clinic-modelling randomised trials in rodents, and has shown promise in some clinical trials for indications other than preoperative prophylaxis. It has also enhanced host defence and has been anti-inflammatory in basic research. Conclusion: The following hypothesis will be tested in patients with operations for colorectal cancer and increased preoperative risk (ASA 3 and 4): is the outcome as evaluated by the hermeneutic endpoint (quality of life expressed by the patient) and mechanistic endpoints (mortality rate, complication rate, relative hospital stay, assessed by the doctor) improved in the group receiving filgrastim prophylaxis in comparison with the placebo group? Quality of life will be the first primary endpoint in the hierarchical, statistical testing of confirmatory analysis.

Item does not contain fulltext GENERAL DESIGN: Presentation of a new type of a study protocol for evaluation of the effectiveness of an immune modifier (rhG-CSF, filgrastim): prevention of postoperative infectious complications and of sub-optimal recovery from operation in patients with colorectal cancer and increased preoperative risk (ASA 3 and 4). A randomised, placebo controlled, double-blinded, single-centre study is performed at an University Hospital (n = 40 patients for each group). This part presents the course of the individual patient and a complication algorithm for the management of anastomotic leakage and quality management. OBJECTIVE: In part three of the protocol, the three major sections include: The course of the individual patient using a comprehensive graphic display, including the perioperative period, hospital stay and post discharge outcome. A center based clinical practice guideline for the management of the most important postoperative complication--anastomotic leakage--including evidence based support for each step of the algorithm. Data management, ethics and organisational structure. CONCLUSIONS: Future studies with immune modifiers will also fail if not better structured (reduction of variance) to achieve uniform patient management in a complex clinical scenario. This new type of a single-centre trial aims to reduce the gap between animal experiments and clinical trials or--if it fails--at least demonstrates new ways for explaining the failures.

The characteristics of different crystal growth techniques which are successfully used for the fabrication of epitaxial layers of CdTe, ZnTe, CdSe and ZnSe are compared. These techniques can be divided into two groups: first, the hot-wall-epitaxy and the hot-wall-beam-epitaxy working close to thermodynamic equilibrium, and second the atomic-layer epitaxy and the self-limiting monolayer epitaxy, which take some advantage to operate far away from thermodynamic equilibrium. With both groups of techniques epilayers and layered structures of high quality could be grown.

X‐ray rocking curves of (100) and (111) oriented CdTe epilayers grown by hot wall epitaxy on (100) GaAs substrates have been measured. Our results indicate that the number of extended defects increases with thickness in (111) CdTe epilayers but decreases with thickness in (100) CdTe epilayers. The distortion of the GaAs surface induced by the CdTe epilayer is determined from comparative measurements of the rocking curve of the covered and uncovered GaAs substrate.

Illumination of CdS at room temperature with the green (514 nm) line of an Ar/sup +/ laser may lead to intrinsic photothermal-induced absorption optical bistability. If the samples are covered with two metal contacts resulting in a small slit, the additional feedback introduced through the photocurrent by Joule's heat may lead to a reduction of the necessary optical input power. In particular, CdS single-crystal platelets, CdS epitaxial layers, or CdS evaporated layers contacted with either Au or In are used. The experimental characteristics are compared with detailed model calculations, which explain deviations from ideal behavior. Special emphasis is laid upon the modulator characteristics (i.e. controlling photonics by electronics) and the possibility of controlling electronics by photonics. >

Thin CdS films were prepared with a conventional thermal evaporation technique. Post deposition annealing was carried out in the vacuum chamber to improve the optical properties. Characterizing the layers using absorption spectroscopy showed that the steepness of the absorption edge is improved by the annealing process. It results in values close to those of the bulk material. A grain structure could not be observed with an electron microscope. Furthermore the films show nonlinear behaviour and even photo-thermal optical bistability at reduced temperatures (250 K) at 514 nm. Coevaporation of a second semiconductor material, e.g. ZnS, shifts the band edge of the pure CdS film to the blue. First attempts to obtain optical bistability at room temperature and above with the 514 nm line of the Ar + laser look promising. Depositing electrical contacts onto the film, makes the layer into a SEED-device, operating with photo-thermal effects.