Concurrent Distributed Serving with Mobile Servers

This paper introduces a new resource allocation problem in distributed computing called distributed serving with mobile servers (DSMS). In DSMS, there are k identical mobile servers residing at the processors of a network. At arbitrary points of time, any subset of processors can invoke one or more requests. To serve a request, one of the servers must move to the processor that invoked the request. Resource allocation is performed in a distributed manner since only the processor that invoked the request initially knows about it. All processors cooperate by passing messages to achieve correct resource allocation. They do this with the goal to minimize the communication cost. Routing servers in large-scale distributed systems requires a scalable location service. We introduce the distributed protocol Gnn that solves the DSMS problem on overlay trees. We prove that Gnn is starvation-free and correctly integrates locating the servers and synchronizing the concurrent access to servers despite asynchrony, even when the requests are invoked over time. Further, we analyze Gnn for "one-shot" executions, i.e., all requests are invoked simultaneously. We prove that when running Gnn on top of a special family of tree topologies - known as hierarchically well-separated trees (HSTs) - we obtain a randomized distributed protocol with an expected competitive ratio of O(log n) on general network topologies with n processors. From a technical point of view, our main result is that Gnn optimally solves the DSMS problem on HSTs for one-shot executions, even if communication is asynchronous. Further, we present a lower bound of Omega(max {k, log n/log log n}) on the competitive ratio for DSMS. The lower bound even holds when communication is synchronous and requests are invoked sequentially

Rheological Study of Gelation and Crosslinking in Chemical Modified Polyamide 12 Using a Multiwave Technique

When processing particular polymers, it may be necessary to increase the molecular weight, for example, during polymer recycling or foaming. Chemical additives such as chain extenders (CE) are often used to build up the molecular weight during reactive extrusion. One issue of chain extenders, however, is that they can cause gelation or crosslinking of the polymer during processes with long residence times. This can lead to strong process fluctuations, undesired process shutdowns due to uncontrollable torque and pressure fluctuations and finally consistent material quality cannot be guaranteed. To measure and understand the reactivity between the polymer and the CE a rheological test can help. However, the standard gel point evaluation used for thermosets by examining the point of intersection of storage- and loss modules is not suitable, as this method is frequency-dependent. This study uses a multiwave rheology test to identify the gel-point more reliably. Both evaluation methods were compared on a polyamide 12 system, which is modified with an industrially relevant chain extender. The results show that the multiwave test can be applied on a chemical modified thermoplastic system and that the material system indicates a general tendency to crosslink. The frequency-independent gel-point evaluation shows that the gel-point itself is dependent on the processing temperature. Finally, it was possible to detect undesired side reactions, which are not recognizable with the standard testing method. Both findings are directly relevant for the reactive extrusion process and help to understand the mechanism of gelation

Chapter 4 – Health Apps and Specific Challenges

Die verbreitet gesehenen Potenziale von Apps, entlang der Versorgungskette im Gesundheitswesen zu Kosteneinsparungen und Qualitätsverbesserungen zu führen, erscheinen oft plausibel, sind jedoch nach wissenschaftlichen Standards regelhaft nicht belegt. Bisherige Erfahrungen zeigen insbesondere potenziellen Nutzen beim Einsatz als Adhärenz-fördernder Therapiebestandteil bei Patientinnen und Patienten mit chronischen Erkrankungen sowie beim Monitoring von Gesundheitszuständen, das die Versorgungsqualität steigern und den Kostenaufwand senken kann. Die Vielzahl der Apps mit unterschiedlichsten Funktionen und Einsatzgebieten bietet die Chance, dass besondere Personengruppen spezifische Unterstützungsmöglichkeiten für ihre jeweiligen Problemsituationen erhalten. Qualitativ hochwertige Apps, die ihre Zweckbestimmung verlässlich erfüllen und ausreichende Sicherheit für die Nutzung gewährleisten, bleiben jedoch nach ersten Erfahrungen eher die Ausnahme im Markt. Es bestehen für die Nutzerinnen und Nutzer erhebliche Schwierigkeiten, gute und individuell zweckmäßige Apps zu finden. Entscheidend für die Bedeutung von Apps in der Gesundheitsversorgung scheint die Anknüpfung an bestehende Versorgungsstrukturen und -prozesse zu sein, bei der die Gesundheits-Apps einen definierten Wertbeitrag innerhalb der Versorgungskette leisten.The often recognized potential of apps for cost savings and quality improvements along the supply chain in healthcare seems plausible enough, but is usually not verified according to scientific standards. Previous experiences show particular potential benefits when apps are used as adherence-promoting therapy components in patients with chronic diseases and in the monitoring of health conditions, which can both increase the quality of care and reduce costs. The multitude of apps with diverse functions and application areas offers the chance that special populations receive specific support options for their respective problematic situations. High-quality apps that fulfill their purpose reliably and ensure adequate security when used can are rather considered as an exception in the market. For users, finding good and individually appropriate apps is often difficult. A decisive factor for the success of apps in healthcare seems to be the link with existing supply structures and processes. Only then can health apps provide a defined value contribution within the supply chain

Low-Density Polybutylene Terephthalate Foams with Enhanced Compressive Strength via a Reactive-Extrusion Process

Due to their appealing properties such as high-temperature dimensional stability, chemical resistance, compressive strength and recyclability, new-generation foams based on engineering thermoplastics such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) have been gaining significant attention. Achieving low-density foams without sacrificing the mechanical properties is of vital importance for applications in the field of transportation and construction, where sufficient compressive strength is desired. In contrast to numerous research studies on PET foams, only a limited number of studies on PBT foams and in particular, on extruded PBT foams are known. Here we present a novel route to extruded PBT foams with densities as low as 80 kg/m3 and simultaneously with improved compressive properties manufactured by a tandem reactive-extrusion process. Improved rheological properties and therefore process stability were achieved using two selected 1,3,5-benzene-trisamides (BTA1 and BTA2), which are able to form supramolecular nanofibers in the PBT melt upon cooling. With only 0.08 wt % of BTA1 and 0.02 wt % of BTA2 the normalized compressive strength was increased by 28% and 15%, respectively. This improvement is assigned to the intrinsic reinforcing effect of BTA fibers in the cell walls and struts

Adding epoetin alfa to intense dose-dense adjuvant chemotherapy for breast cancer : randomized clinical trial

BACKGROUND: The AGO-ETC trial compared 5-year relapse-free survival of intense dose-dense (IDD) sequential chemotherapy with epirubicin (E), paclitaxel (T), and cyclophosphamide (C) (IDD-ETC) every 2 weeks vs conventional scheduled epirubicin/cyclophosphamide followed by paclitaxel (EC→T) (every 3 weeks) as adjuvant treatment in high-risk breast cancer patients. The objective of this study was to evaluate the safety and efficacy of epoetin alfa in a second randomization of the intense dose-dense arm. METHODS: One thousand two hundred eighty-four patients were enrolled; 658 patients were randomly assigned to the IDD-ETC treatment group. Within the IDD-ETC group, 324 patients were further randomly assigned to the epoetin alfa group, and 319 were randomly assigned to the non-erythropoiesis-stimulating agent (ESA) control group. Primary efficacy endpoints included change in hemoglobin level from baseline to Cycle 9 and the percentage of subjects requiring red blood cell transfusion. Relapse-free survival, overall survival, and intramammary relapse were secondary endpoints estimated with Kaplan-Meier and Cox regression methods. Except for the primary hypothesis, all statistical tests were two-sided. RESULTS: Epoetin alfa avoided the decrease in hemoglobin level (no decrease in the epoetin alfa group vs -2.20g/dL change for the control group; P < .001) and statistically significantly reduced the percentage of subjects requiring red blood cell transfusion (12.8% vs 28.1%; P < .0001). The incidence of thrombotic events was 7% in the epoetin alfa arm vs 3% in the control arm. After a median follow-up of 62 months, epoetin alfa treatment did not affect overall survival, relapse-free survival, or intramammary relapse. CONCLUSIONS: Epoetin alfa resulted in improved hemoglobin levels and decreased transfusions without an impact on relapse-free or overall survival. However, epoetin alfa had an adverse effect, resulting in increased thrombosis

High-resolution isotopic evidence of specialised cattle herding in the European Neolithic.

Peer reviewe

Innovative Thermal Management Concepts and Material Solutions for Future Space Vehicles

When entering a planetary atmosphere, space vehicles are exposed to extreme thermal loads. To protect the vehicle’s interior, a thermal protection system is required. Future aerospace transportation demands solutions that exceed the performance of current systems and up-to-date material limits. Therefore, new and disruptive solutions must be envisaged to meet those extreme conditions. In the search of new solutions for sharp leading edges of future hypersonic reentry or transport vehicles, the THOR project, composed of eight European organizations (industries, research centers, and universities) and one Japanese Agency (Japan Aerospace Exploration Agency), is actively working on definition, design, implementation, and simulation of new passive and active thermal management solutions and their verification in relevant environments (high-enthalpy facilities). This paper provides an overview of the recent developments on the four concepts that are targeted in the project, applying different physical methodologies: 1) passive cooling using highly conductive carbon-based fibers, 2) passive cooling with intensive internal radiative exchange, 3) active cooling based on convection heat transfer using a ceramic sandwich/thermal protection system with ceramic foams/lattices, and 4) active transpiration cooling of external surfaces. Details on these thermal management concepts, requirements from end users, and test configurations, as well as results from experimental and numerical verification, are given

The walls of gated communities in Brazil and Turkey: security, separation or status?

Gated communities are common types of housing estates found in many countries. They are based on strictly controlled access of people. Houses, and at times high-rise apartment blocks, are built behind a common wall, along private internal streets. Both in Brazil and in Turkey these types of residential neighborhoods can be found mainly on the outskirts of large urban areas. This paper investigates the reasons for the increase of such residential areas, in relation to the two countries urban problems. In Brazil the dominant reason for the proliferation of gated communities, found in the literature and in advertisement of such estates, is security, in view of the countries high crime rates. In Turkey the main reason for a family to choose to live in such residential areas is status and privacy. Although Brazil and Turkey have very different cultural backgrounds, in both countries gated communities are increasingly popular. The attraction of these so-called communities must therefore be analyzed. Are people more vulnerable in large mega-cities? Also, the impact on urban prospects as a whole must be discussed. Socio-cultural and psychological concepts such as territoriality, security, privacy, which can be represented by a pattern of behavior of an individual or group, as based on control of space, are thus touched on in the paper. Conclusions confirm that the reasons for preferences for gated communities are the feeling of belonging to a special place, fear of crime and a sense security and determine decision making of families in their homeownership choices

Search for supersymmetry with a dominant R-parity violating LQDbar couplings in e+e- collisions at centre-of-mass energies of 130GeV to 172 GeV

A search for pair-production of supersymmetric particles under the assumption that R-parity is violated via a dominant LQDbar coupling has been performed using the data collected by ALEPH at centre-of-mass energies of 130-172 GeV. The observed candidate events in the data are in agreement with the Standard Model expectation. This result is translated into lower limits on the masses of charginos, neutralinos, sleptons, sneutrinos and squarks. For instance, for m_0=500 GeV/c^2 and tan(beta)=sqrt(2) charginos with masses smaller than 81 GeV/c^2 and neutralinos with masses smaller than 29 GeV/c^2 are excluded at the 95% confidence level for any generation structure of the LQDbar coupling.Comment: 32 pages, 30 figure