Evaluating and improving the content access in KAD

We analyze in detail the content retrieval process in kad. kad implements content search (publish and retrieval) functions that use the Kademlia Distributed Hash Table for content routing. Node churn is quite common in peer-to-peer systems and results in information loss and stale routing table entries. To deal with node churn, kad issues parallel route requests and publishes multiple redundant copies of each piece of information. We identify the key design parameters in kad and present an analytical model to evaluate the impact of changes in the values of these parameters on the overall lookup latency and message overhead. Extensive measurements of the lookup performance using an instrumented client allow us to validate the model. The overall lookup latency is in most cases 5 s or larger. We elucidate the cause for such high lookup latencies and propose an improved scheme that significantly decreases the overall lookup latency without increasing the overhead.     

Modeling and performance comparison of reliability strategies fordistributed video servers

Large scale video servers are typically based on disk arrays that comprise multiple nodes and many hard disks. Due to the large number of components, disk arrays are susceptible to disk and node failures that can affect the server reliability. Therefore, fault tolerance must be already addressed in the design of the video server. For fault tolerance, we consider parity-based as well as mirroring-based techniques with various distribution granularities of the redundant data. We identify several reliability schemes and compare them in terms of the server reliability and per stream cost. To compute the server reliability, we use continuous time Markov chains that are evaluated using the SHARPE software package. Our study covers independent disk failures and dependent component failures. We propose a new mirroring scheme called Grouped One-to-One scheme that achieves the highest reliability among all schemes considered. The results of this paper indicate that dividing the server into independent groups achieves the best compromise between the server reliability and the cost per stream. We further find that the smaller the group size, the better the trade-off between a high server reliability and a low per stream cost     

Synthesis and Anticancer Evaluation of New Indole-Based Tyrphostin Derivatives and Their (p-Cymene)dichloridoruthenium(II) Complexes

New N-alkylindole-substituted 2-(pyrid-3-yl)-acrylonitriles with putative kinase inhibitory activity and their (p-cymene)Ru(II) piano-stool complexes were prepared and tested for their antiproliferative efficacy in various cancer models. Some of the indole-based derivatives inhibited tumor cell proliferation at (sub-)micromolar concentrations with IC₅₀ values below those of the clinically relevant multikinase inhibitors gefitinib and sorafenib, which served as positive controls. A focus was set on the investigation of drug mechanisms in HCT-116 p53-knockout colon cancer cells in order to evaluate the dependence of the test compounds on p53. Colony formation assays as well as experiments with tumor spheroids confirmed the excellent antineoplastic efficacy of the new derivatives. Their mode of action included an induction of apoptotic caspase-3/7 activity and ROS formation, as well as anti-angiogenic properties. Docking calculations with EGFR and VEGFR-2 identified the two 3-aryl-2-(pyrid-3-yl)acrylonitrile derivatives 2a and 2b as potential kinase inhibitors with a preferential activity against the VEGFR-2 tyrosine kinase. Forthcoming studies will further unveil the underlying mode of action of the promising new derivatives as well as their suitability as an urgently needed novel approach in cancer treatment.     

Assessment of regional myocardial uptake and metabolism of omega-(p-123I-phenyl) pentadecanoic acid with serial single-photon emission tomography

The utility of myocardial imaging and assessment of regional myocardial metabolism of omega-(123I-paraphenyl-)pentadecanoic acid (I-PPA) by means of serial single-photon tomography is demonstrated in animal experiments. High quality cross sectional images of dog hearts with clear delineation of left ventricular walls are obtained. Myocardial infarcts are visualized as areas of deficient radioactivity uptake. I-PPA elimination from non-infarcted myocardial regions is significantly (p less than 0.001) prolonged when compared with unaffected controls. Hence, not only localized absence of uptake of free fatty acid by infarcted myocardium can be demonstrated with serial single-photon tomography but also general impairment of cardiac FFA-metabolism.     

Rhenium-186 HEDP: palliative radionuclide therapy of painful bone metastases. Preliminary results

Dengue hemorrhagic fever is a common tropical disease in Thailand that nowadays has an increasing incidence during adulthood. We managed three cases of dengue hemorrhagic fever during pregnancy which developed during the antepartum, intrapartum and postpartum periods. We diagnosed dengue hemorrhagic fever during pregnancy with clinical pictures of fever, hemoconcentration and thrombocytopenia with serological proof in all cases. All cases were treated conservatively except for the second one, in which cesarean delivery was inevitable due to severe preeclampsia with unfavorable cervix. All patients and their babies were in good condition before discharge. With increasing incidence during adulthood, more cases of dengue hemorrhagic fever in pregnancy can be found. Conservative treatment should be conducted in all cases. We believe that this is the first case report of intrapartum dengue hemorrhagic fever during pregnancy.     

Functional imaging of Hodgkin's disease with FDG-PET and gallium-67

We report a case of Hodgkin's lymphoma (Stage I B) which was studied using Ga-67-scintigraphy as well as whole body FDG-PET. Ga-67-scintigraphy detected a slightly increased uptake in the paraaortic and pelvic lymph nodes. However, FDG-PET was able to localize a much larger number of affected foci with a high glucose utilization rate in the right and left paraaortal regions, in the middle of the epigastrium, in the right and left parailiacal regions and one focus in the left upper mediastinum. Our experiences give rise to the assumption that FDG-PET ist significantly superior to gallium scintigraphy in Hodgkin's disease. Whole body FDG-PET can result in an upstaging of the patient and has therefore a major impact on the therapeutic management.     

Annotated bibliography on network interconnection

This bibliography covers the various aspects of network interconnection. It contains a list of papers, documents, and books dealing with interconnection at different layers of the ISO OSI reference model and covers topics such as interconnection among various types of networks, backbone networks, standardization efforts, interconnection techniques, formal approaches, network management, protocol issues, addressing and naming, routing, performance evaluation, gateway implementations, and existing products     

The use of the liver-spleen-scan for the diagnosis of congenital Intrahepatic cysts of the bile duct (M. Caroli) (authors transl)

After the short review of the pathogenesis, diagnosis and therapy for congenital intrahepatic cysts of the bile-duct (morbus Caroli), reference was made to the diagnostic significance of liver scintigraphy on the basis of two casuistic reports. Liver scintigraphy permits an exact localization of intrahepatic cysts as well as information regarding the course of the hepatopathy connected with morbus Caroli. In addition, 131-J-bromsulfon scintigraphy of the liver is a simple method for controlling the patency of the bile ducts. Our observations tend to indicate that preoperative and postoperative scintigraphic controls of the liver are practical for this disease.     

Range profiles of implanted Bi and Au in amorphous silicon

The Rutherford backscattering technique is used to measure the depth profiles for 10 to 390 keV ²⁰⁹Bi and 15 to 390 keV ¹⁹⁷Au implanted in amorphized silicon wafers. The obtained projected ranges and projected range stragglings are compared with previous data and with recent universal range-energy calculations. Whereas good agreement is found between the experimental and theoretical range predictions for Bi, the measurements for Au yield, at low energies, ranges longer than predicted. The discrepancy between measured Au and Bi ranges is ascribed to the Z₁-range oscillation.     

Significance of inhalation and perfusion scintigraphy for the diagnosis of pulmonary embolism (author's transl)

Inhalation and perfusion scintigrams, general radiological examination of the thorax and an EKG were done on 43 patients with clinically suspected pulmonary embolism. In 11 cases, the clinical diagnosis could be confirmed on the basis of the scintigraphic examination. In the remaining 32 patients, an embolich event could be excluded by pulmonary scintigram, radiological examination and later the clinical course. A synopsis of clinical observations, X-ray and scintigraphy, therefore, permitted a basically reliable diagnosis of pulmonary embolism; selective pulmonary angiography should be used only in exceptional cases.