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We consider the problem of assigning flights to airport gates. We examine the general case in which an aircraft serving a flight may be assigned to different gates for arrival, parking, and departure processing. The objectives can be divided into deterministic and stochastic goals. The former include maximization of the total assignment preference score, a minimal number of unassigned flights during overload periods, and minimization of the number of tows. A special focus lies on the stochastic objectives, which aim at minimizing the expected number of any kind of constraint violations, i.e. not respecting gate closures, violation of shadow restrictions (a situation in which gate assignments may cause blocking of neighboring gates) or of tow time restrictions and classical gate conflicts in which two aircraft are assigned to the same gate and are at the airport at the same time. We show that the minimization of expected gate conflicts can be modeled in a graph theoretical approach using the clique partitioning problem (CPP). We furthermore show that the classical (deterministic) flight gate assignment problem, which can also be modeled using a CPP, can be integrated such that a simple though powerful model emerges, which no longer needs including a dummy gate, which is often used in practical gate assignment models. As constraint violations cannot fully be prevented, recovery strategies become necessary. We present a procedure for recovery planning that has proved its practical relevance at numerous airports. Finally, in an extensive numerical study we test our results on practical data, which contain a statistical analysis of flight arrival and departure times. The tests include a detailed comparison of current robustness measures and state-of-the-art approaches found in literature.

Electric arc furnaces (EAFs) represent ∼32% of the world’s steel production and are designed as flexible metallurgical production units. Roughly 80% of these EAFs constitute the main metallurgical ...

Purpose of this study was to define a subgroup of TIA/stroke patients who should be examined by transthoracal and transesophageal echocardiography or Holter-electrocardiography to identify those with cardiogenic brain embolism reliably; 300 consecutive patients with acute focal brain ischemia underwent a standardized diagnostic protocol for the evaluation of the etiology including, clinical examination by a cardiologist and routine electrocardiography, Holter-electrocardiography, transthoracal and transesophageal echocardiography. 188 patients had a potential cardiac source of embolism. In particular echocardiography was diagnostic in 163 patients, and Holter-electrocardiography 10; 159 of these 188 patients (84.6%) had competitive etiologies, predominantly large vessel atherosclerosis. In 136 patients cardiogenic brain embolism was assumed as quite definite or possible. To identify these patients reliably, transthoracal and transesophageal echocardiography would have been necessary in 89% of the entire group of patients (all with clinically cardiological abnormalities, pathological routine ECG, without vascular risk factors, or no atherosclerosis in duplex sonography), and Holter-electrocardiography in 54%.

Introduction - MELAS is most often due to an maternally transmitted A-G transition mutation of mitochondrial DNA (mt DNA) at position 3243. In this study we report on the clinical spectrum associated with the mutation in the largest family reported so far. Patients and methods - In a family with three MELAS cases we identified 47 persons at risk for the mutation ; sufficient data was available on 29. Mitochondrial disease was diagnosed in two of 9 deceased members (posthumous molecular analysis in one) ; 27 surviving family members underwent examination and 25 a molecular analysis of mt DNA from lymphoblasts. Then had a muscle biopsy and two were later autopsied. Results - All 26 cases investigated by molecular analysis showed the mutation at position 3243. The 18 symptomatic patients without stroke-like episodes had sensorineural hearing loss in 15 cases, diabetes in 6, nephropathy in 7, mild myopathy in 4, cardiomyopathy in 2, cerebellar disease in 4 and mental retardation in 2 cases. Eight carriers were asymptomatic. Autopsy showed > 80% mutant mt DNA in all tissues except blood (20%) examined in a MELAS patient, but

During a four-week trip to Nigeria a 54-year-old German developed a fever of 39 degrees C. Later on he had lymphadenopathy, pretibial oedema, dyspnoea and weight loss. After 16 weeks a wreath-like pale pink skin rash, increased pulse rate with pulse deficit and hepatosplenomegaly were noted. Abnormal laboratory findings were an increased blood sedimentation rate (95 mm), raised immunoglobulin M (483 mg/dl), haemoglobin of 12.0 g/dl, mean corpuscular volume of 76 fl and Borrelia IgM antibody titre of 1:512. The electrocardiogram was suggestive of myocarditis: the cardiac symptoms were controlled with digoxin and verapamil. The patient's general condition deteriorated while he was receiving antibiotic treatment with tetracycline and penicillin. Cerebrospinal fluid (CSF) showed an increased cell count (39/microliters) and albumin (0.98 g/dl). There was a mild, predominantly proximal, tetraplegia which--on the basis of electromyographic and biopsy findings--was thought to be due to polyneuritis and myositis. At this stage blood smear and CSF examination revealed Trypanosoma. He thereupon received suramin (1.0 g) and prednisolone (120 mg down to 40 mg) daily, to which melarsoprol was added after 6 days (0.5 ml up to 5.0 ml daily for 36 days). Almost all symptoms then regressed within 6 weeks.

Technical improvements accomplished over the last few years allow imaging of intracranial parenchymal structures as well as of basal cerebral arteries by ultrasound. Low frequency probes (2-2.5 MHz) and colour Doppler technology are required for these examinations. Recent experience in clinical practice proves that perfusion patterns in basal cerebral arteries can be depicted more accurately and with better reproducibility compared to conventional transcranial Doppler sonography. Simultaneous B-Mode imaging allows detection of cerebral haemorrhage, brain tumours and ventricular enlargement. Preliminary data on the sensitivity and specificity are promising and encourage further prospective studies.

This paper introduces models of robustness in flight gate assignments at airports. We briefly repeat the general flight gate assignment problem and disruptions occurring in airline scheduling. Recovery strategies and robust scheduling are surveyed as the main methods in disruption management. We present a non-robust flight gate assignment model and incorporate two approaches of robustness.

A general rule of thumb for biological conservation obtained from simple models of hypothetical species is that for populations with strong environmental noise moderate increases in habitat size or quality do not substantially reduce extinction risk. However, whether this rule also holds for real species with complex behavior, such as social species with breeding units and reproductive suppression, is uncertain. Here we present a population viability analysis of the alpine marmot Marmota marmota, which displays marked social behavior, i.e. it lives in social groups of up to twenty individuals. Our analysis is based on a long-term field study carried out in the Bavarian Alps since 1982. During the first fifteen years of this study, 687 marmots were individually marked and the movements and fate of 98 dispersing marmots were recorded with radio-telemetry. Thus, in contrast to most other viability analyses of spatially structured populations, good data about dispersal exist. A model was constructed which is individual-based, spatially explicit at the scale of clusters of neighbouring territories, and spatially implicit at larger scales. The decisive aspect of marmot life history, winter mortality, is described by logistic regression where mortality is increased by age and the severity of winter, and decreased by the number of subdominant individuals present in a group. Model predictions of group size distribution are in good agreement with the results of the field study. The model shows that the effect of sociality on winter mortality is very effective in buffering environmental harshness and fluctuations. This underpins theoretical results stating that the appropriate measure of the strength of environmental noise is the ratio between the variance of population growth rate and the intrinsic rate of increase. The lessons from our study for biological conservation are that simple, unstructured models may not be sufficient to assess the viability of species with complex behavioral traits, and that even moderate increases in habitat capacity may substantially reduce extinction risk even if environmental fluctuations seem high.

Publiziert im Rahmen des KTI Projektes Sales Forecasting Absatzprognosen sind die Basis eines erfolgreichen Supply Chain Managements. Täglich beschäftigen sich Disponenten insbesondere bei Lebensmitteln mit der Frage, welche Faktoren den Absatz beeinflussen, wie sich Produkte z.B. bei Promotionen kannibalisieren oder wie genau das Wetter in den Bedarf hineinspielt. Menschen können nicht an alles denken, was den Absatz beeinflussen könnte, haben dafür aber ein lange antrainiertes Bauchgefühl. Algorithmen können zwar im Prinzip alles berücksichtigen, oft fehlt aber gerade im Handel die nötige Datenbasis. Es braucht daher Entwicklungen, welche die Stärken von Mensche (Intuition) und von Maschinen (Handling der Komplexität) kombinieren.

Only few exact solution methods are available for the open shop scheduling problem. We describe a branch-and-bound algorithm for solving this problem which performs better than other existing algorithms. The key to the efficiency of our algorithm lies in the following approach: instead of analysing and improving the search strategies for finding solutions, we focus on constraint propagation based methods for reducing the search space. Extensive computational experiments on several sets of well-known benchmark problem instances are reported. For the first time, many problem instances are solved to optimality in a short amount of computation time. Copyright © 2001 John Wiley & Sons, Ltd.

Objective - The expression of intercellular adhesion molecule-3 (ICAM-3), a member of the Ig supergene family, is restricted to immune competent cells. Expression of soluble and cell surface ICAM-3 (s- and c-ICAM-3) is preferentially seen in the state of low activation of the immune system. We studied the relevance of the expression levels of sand c-ICAM-3 in cerebrospinal fluid (CSF) and blood as markers for disease activity as well as the influence of high-dose methylprednisolone (MP) treatment upon the expression of s- and c-ICAM-3 in blood of patients with multiple sclerosis (MS). Materials and methods - A total of 33 patients (relapses n = 25, remission n = 8) with relapsing-remitting MS were included into the study. CSF and blood were acquired from all of them. Of the patients 24 were treated with high-dose MP. In those, blood was additionally collected at the 10th day of the therapy and after 3 months. Expression of c-ICAM-3 was determined by two colour FACS analysis, whereas the concentration levels of s-ICAM-3 were measured by ELISA, Results - In CSF we detected a significant decrease of the expression levels of c-ICAM-3 on CD3 + T cells in 25 patients suffering from an acute relapse in contrast to 8 patients with remission (P=0.04). In comparison to the levels before treatment and after 3 months, at the 10th day of MP treatment we obtained highly significant changes of the expression values of c-ICAM-3 both on CD3 + T cells (P=0.0004; P=0.005) and CD14 + monocytes/macrophages (P=0.0006; P=0.008) on the 10th day of high-dose MP treatment from 24 MS patients. Conclusion - The increase of ICAM-3 levels might indicate the antiinflammatory effect of the MP treatment. It could be interesting to search for similar effects investigating the new immune modulatoring therapy forms of MS.

Background and Purpose —Transcranial color-coded duplex sonography (TCCS) of intracranial veins and sinuses in adults is a new, emerging application of ultrasonographic imaging. This study reports a standardized examination protocol for venous TCCS and provides reference data for clinical application. Methods —In 130 healthy volunteers (mean age, 45.9±16.9 years; range, 14 to 77 years) the intracranial venous system was examined using frequency-based transtemporal TCCS. Identification rate, blood flow velocity , resistance index, and systolic/diastolic ratio were recorded for each examined venous vessel. Results —Intracranial veins and sinuses show a low pulsatile forward flow with maximal systolic blood flow velocity up to 20 cm/s. Significant side differences of blood flow velocity in the paired venous structures could not be detected. Venous flow velocities decreased with age, whereas resistance indices and systolic/diastolic ratios increased. Women showed higher flow velocities than men. Mean identification rates for all age groups ranged from 70% to 90% for the deep middle cerebral vein, the basal cerebral vein, and the great cerebral vein of Galen. The straight sinus, the transverse sinus, and the rostral part of the superior sagittal sinus could be detected in 55% to 70% of cases. Detection rates were dependent on age and decreased as age increased. Conclusions —Venous TCCS can reliably image a significant part of the cerebral venous system. This method can provide information on venous hemodynamics in normal subjects and pathological cases.

Injection-induced palsy of the ischiatic nerve with concomitant damage of other peripheral nerves occurred in two patients following intramuscular injection in the upper outer quarter of the large gluteal muscle. In close chronological connection skin changes developed in both cases representing drug-induced cutaneous embolism, and in one case extensive muscular necrosis was observed. In both cases the cause may be assumed to be ischaemic neuropathy following embolic occlusion of the vasa nervorum as a result of accidental intraarterial injection.

Eight carriers of the A3243G mutation of mitochondrial DNA without stroke-like episodes were monitored for up to 7 years in clinical and metabolic studies, by magnetic resonance imaging (MRI) and positron emission tomography (PET). None developed mitochondrial encephalopathy (MELAS), but 2 developed diabetes mellitus, 1 terminal kidney failure and 2 cardiomyopathy. One patient improved markedly under ubiquinone. Electroencephalography showed progressive slowing in 2 cases, but electrophysiological tests and MRI were otherwise noncontributary. PET showed widespread cortical and basal ganglion metabolic deficits in 6 cases. We conclude that internal medical complications are more common than MELAS in adult carriers of the mutation. PET findings, firstly reported in such patients, suggest that chronic subclinical encephalopathy is very frequent, and PET may play a role in monitoring in the future. Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.