Objektorientierte Entwurfsmuster und Frameworks in der Informatik-Ausbildung an der Fachhochschule Konstanz

Zusammenfassung   In den letzten Jahren wurden zwei Konzepte entwickelt, welche die Wiederverwendung von Entwurfserfahrung erlauben. Dies sind zum einen Entwurfsmuster, welche lokale, sich jeweils auf wenige Klassen beziehende Entwurfserfahrung zur Wiederverwendung durch andere Entwickler verfügbar machen, zum anderen Frameworks. Diese erlauben die Wiederverwendung einer globalen Art von Entwurfserfahrung, welche wesentliche Aspekte einer Anwendung umfa?t. Dieser Artikel erl?utert Erfahrungen mit Entwurfsmustern bei der Frameworkentwicklung. An einem Beispielprojekt erl?utert er die erfolgreiche Arbeit von Studenten mit diesen Methoden. Das Ergebnis ermuntert zur Aufnahme entsprechender Methoden in die Informatiker-Ausbildung. Eingegangen am 09.09.1997, in überarbeiteter Form am 04.11.1997     

Growth of II-IV-V<Subscript>2</Subscript> chalcopyrite nitrides by molecular beam epitaxy

Synthesis of crystalline MgGeN₂ thin solid films is achieved using the technique of molecular beam epitaxy (MBE). The details of the epitaxial process are described. The microstructures of these films are investigated by both x-ray diffraction (XRD) and cross-sectional transmission electron microscopy (XTEM). Comparison of the lattice structure with powder diffraction standards suggests the lattice structure may be orthorhombic with a high degree of texture. Morphology is evaluated by atomic force microscopy, and a periodic pattern of growth mounds is observed. A formalism for dynamical roughening is applied to quantify the mounded surface features. Mounds are found to have an average spacing of 235 nm, and the surface exhibits a saturation value of 22 nm for the root mean correlated height difference. Diffusion bias is discussed as a mechanism for the formation of surface mounds.     

Design and characterization of a high average power slab YAG laser

The detailed design and characterization of a zigzag optical path laser with a0.6 times 2 times 15cm Nd:YAG slab is described. Beam distortions arising from nonuniform pumping of the slab and from various end effects are diagnosed, and the implementation of corrective measures is explained. We report on the device performance of the free running oscillator with 70 W output at 1.06 μm and the amplifier with parasitic suppression in which a small signal amplification of 45X was achieved.     

Drying temperature,endogenous antioxidants and capsaicinoids affect carotenoid stability in paprika (red pepper spice)

The major carotenoids and carotenoid esters in Capsicum annuum L. during thermal dehydration of pepper and storage of the ground product (paprika) were examined with special focus on the role of endogenous antioxidants such as vitamins E and C and capsaicinoids, the pungent materials in hot spice red pepper. A high‐performance liquid chromatographic (HPLC) method was developed to achieve excellent separation and accurate detection of different carotenoid classes including free xanthophylls, monoesters, carotenes and di‐esters. The newly developed method included gradient elution on a reversed‐phase column with increasing proportions of isopropanol. The results indicated that presence of capsaicinoids in pungent pepper had a favourable effect on the stability of carotenoids during thermal drying. Among various di‐esters those of lutein and zeaxanthine, as well as the mono‐ester of β‐cryptoxanthin were more stable than those of capsorubin and capsanthin, pointing to the possible role of epoxide and carbonyl groups in the susceptibility of carotenoids. An Arrhenius plot for degradation of carotenoids, tocopherols and ascorbic acid as a function of drying temperature showed linear relationships for all components, with ascorbic acid being the most sensitive. During storage in a refrigerator for 3 months the paprika showed high degradation of all the examined carotenoids particularly in samples prepared from pods dried at high temperatures (90 and 100 °C). An exception was for β‐cryptoxanthin mono‐ester and violaxanthin di‐esters in a non‐pungent variety. The amounts of these carotenoids lost during storage were slightly affected by the change in drying temperature. Strong correlation was found between retention of colour in stored paprika and the initial content of ascorbic acid, but not with that of tocopherols or capsaicinoids. Copyright © 2006 Society of Chemical Industry     

Current information on the composition and breed distribution of urinary stones in dogs

5706 canine urinary stones were analyzed by means of infrared spectroscopy from 1984-1996. The stones were sent in together with epidemiologic data (breed, age, sex, localisation of the stones, type of stone removal, stone frequency etc.) by more than 800 veterinarians from Germany, the Netherlands, Austria, and Switzerland. Irrespective of stone type, urinary stones were observed in almost all breeds, but small breeds like dachshound, poodle, terrier, schnauzer, and pekingese have a higher tendency to form stones. With 59.5% struvite is the most frequent stone type, followed by cystine with 15.5%. Cystine stones are becoming less frequent during the observation time, whereas the share of calcium oxalate (14.2%) and ammonium urate (6.0%) stones remains unchanged. The latter stone types are found predominantly in specific breeds. The stone formation appears predominantly at the age of 7. Male dogs form stones twice as often as female dogs. 98% of the stones were located in the lower urinary tract. About 90% of the urinary stones required surgical treatment.     

Agglutination of Plasmodium falciparum-infected erythrocytes from east and west African isolates by human sera from distant geographic regions

Plasmodium falciparum-infected erythrocytes (PfE) were collected from acutely infected children in The Gambia and Tanzania and cultured for more than 30 hr until the parasites were mature trophozoites. Sera collected from these countries, other African countries, Asia, and South America were used in the PfE microagglutination test to determine whether PfE from East and West Africa share surface antigens. From the patterns of agglutination reactivity, we identified extensive antigenic diversity in surface antigens, but obtained no evidence for greater differences between isolates from East or West Africa and those within one region. The majority of sera from immune adults from The Gambia, Tanzania, Sudan, Nigeria, or Ghana were pan-agglutinating, and agglutinated all PfE isolates from The Gambia and Tanzania. Some sera from immune adults of Irian Jaya also agglutinated each of the seven African isolates, while others agglutinated many but not all of the isolates, similar to sera from immune adults of Flores, Indonesia. In contrast, sera from nonimmune adults from Colombia agglutinated few of the African isolates. It was remarkable, however, that sera from nonimmune Colombians agglutinated any African isolates. Our results are consistent with the following conclusions: some PfE surface antigen(s) are very diverse; this diversity is a feature of the parasite worldwide; the repertoire of isolate-specific surface antigens, although large, includes antigens that are either identical or antigenically cross-reactive in geographically very distant parasite populations; and African adults have pan-agglutinating antibodies that may contribute to protective immunity. Such pan-agglutinating antibodies could reflect the accumulation of a large repertoire of isolate-specific antibodies. The contribution of antibody against any shared PfE surface antigen to the pan-agglutinating reactivities is unknown and awaits development of the appropriate reagents.     

Timing of surgery in patients with aneurysmal subarachnoid haemorrhage: rebleeding is still the major cause of poor outcome in neurosurgical units that aim at early surgery

OBJECTIVE: To investigate prospectively the proportion of patients actually operated on early in units that aim at surgery in the acute phase of aneurysmal subarachnoid haemorrhage (SAH) and what is the main current determinant of poor outcome. METHODS: A prospective analysis of all SAH patients admitted during a one year period at three neurosurgical units that aim at early surgery. The following clinical details were recorded: age, sex, date of SAH, date of admission to the neurosurgical centre, whether a patient was referred by a regional hospital or a general practitioner, Glasgow coma scale and grade of SAH (World Federation of Neurological Surgeons (WFNS) score) on admission at the neurosurgical unit, results of CT and CSF examination, the presence of an aneurysm on angiography, details of treatment with nimodipine or antifibrinolytic agents, and the date of surgery to clip the aneurysm. At follow up at three months, the patients' clinical outcome was determined with the Glasgow outcome scale and in cases of poor outcome the cause for this was recorded. RESULTS: The proportion of patients that was operated on early--that is, within three days after SAH--was 55%. Thirty seven of all 102 admitted patients had a poor outcome. Rebleeding and the initial bleeding were the main causes of this in 35% and 32% respectively of all patients with poor outcome. CONCLUSIONS: In neurosurgical units with what has been termed "modern management" including early surgery, about half of the patients are operated on early. Rebleeding is still the major cause of poor outcome.