Schedules for Dynamic Bidirectional Simulations on Parallel Computers

For adjoint calculations, parameter estimation, and similar purposes one may need to reverse the execution of a computer program. The simplest option is to record a complete execution log and then to read it backwards. This requires massive amounts of storage. Instead one may generate the execution log piecewise by restarting the ``forward'' calculation repeatedly from suitably placed checkpoints. This thesis extends the theoretical results of the parallel reversal schedules. First a algorithm was constructed which carries out the ``forward'' calculation and distributes checkpoints in a way, such that the reversal calculation can be started at any time. This approach provides adaptive parallel reversal schedules for simulations where the number of time steps is not known a-priori. The number of checkpoints and processors used is optimal at any time. Further, an algorithm was described which makes is possible to restart the initial computer program during the program reversal. Again, this can be done without any additional computation at any time. Hence, optimal parallel reversal schedules for the bidirectional simulation are provided by this thesis.Bei der Berechnung von Adjungierten, zum Debuggen und für ähnliche Anwendungen kann man die Umkehr der entsprechenden Programmauswertung verwenden. Der einfachste Ansatz, nämlich das Erstellen einer kompletten Mitschrift der Vorwärtsrechnung, welche anschließend rückwärts gelesen wird, verursacht einen enormen Speicherplatzbedarf. Als Alternative dazu kann man die Mitschrift auch stückweise erzeugen, indem die Programmauswertung von passend gewählten Checkpoints wiederholt gestartet wird. In dieser Arbeit wird die Theorie der optimalen parallelen Umkehrschemata erweitert. Zum einen erfolgt die Konstruktion von adaptiven parallelen Umkehrschemata. Dafür wird ein Algorithmus beschrieben, der es durch die Nutzung von mehreren Prozessen ermöglicht, Checkpoints so zu verteilen, daß die Umkehrung des Programmes jederzeit ohne Zeitverlust erfolgen kann. Hierbei bleibt die Zahl der verwendeten Checkpoints und Prozesse innerhalb der bekannten Optimalitätsgrenzen. Zum anderen konnte für die adaptiven parallelen Umkehrschemata ein Algorithmus entwickelt werden, welcher ein Restart der eigentlichen Programmauswertung basierend auf der laufenden Programmumkehr erlaubt. Dieser Restart kann wieder jederzeit ohne Zeitverlust erfolgen und die entstehenden Checkpointverteilung erfüllen wieder sowohl Optimalitäts- als auch die Adaptivitätskriterien. Zusammenfassend wurden damit in dieser Arbeit Schemata konstruiert, die bidirektionale Simulationen ermöglichen

Entrepreneurial ecosystems: a dynamic lifecycle model

The concept of entrepreneurial ecosystems has been used as a framework to explain entrepreneurial activities within regions and industrial sectors. Despite the usefulness of this approach, the concept is under-theorized, especially with regard to the evolution of entrepreneurial ecosystems. The current literature is lacking a theoretical foundation that addresses the development and change of entrepreneurial ecosystems over time and does not consider the inherent dynamics of entrepreneurial ecosystems that lead to their birth, growth, maturity, decline, and re-emergence. Taking an industry lifecycle perspective, this paper addresses this research gap by elaborating a dynamic entrepreneurial ecosystem lifecycle model. We propose that an ecosystem transitions from an entrepreneurial ecosystem, with a focus on new firm creation, towards a business ecosystem, with a core focus on the internal commercialization of knowledge, i.e., intrapreneurial activities, and vice versa. Our dynamic model thus captures the oscillation that occurs among entrepreneurs and intrapreneurs through the different phases of an ecosystem’s lifecycle. Our dynamic lifecycle model may thus serve as a starting point for future empirical studies focusing on ecosystems and provide the basis for a further understanding of the interrelatedness between and co-existence of new and incumbent firms

A post-mortem evaluation of an IT project: a case study of a process enhancement IT-project in a maintenance, repair and overhaul company

The present work represents a post mortem evaluation of an SAP-IT project. It focuses on critical success factors(CSF) in order to establish an appropriate guideline for the project evaluation.A review of contemporary project management literature identifies general project CSF and SAP-project specificCSF and provides a brief theoretical overview of the purpose of project reviews and points out difficulties regardingperformance measurements.The review of the project is a qualitative evaluation based on selected CSF.Project evaluation is an ongoing, multidimensional process and can be used to measure success and to learn fromprevious experience.The CSF used to measure the project success, need to be well defined and constantly checked as they can changeover time. For project success a good communication with all stakeholders involved is fundamental. Constantreview becomes necessary in today’s complex project world in order to engage in total quality management andcontinuous improvement

Method for the semantic indexing of concept hierarchies, uniform representation, use of relational database systems and generic and case-based reasoning

This paper presents a method for semantic indexing and describes its application in the field of knowledge representation. Starting point of the semantic indexing is the knowledge represented by concept hierarchies. The goal is to assign keys to nodes (concepts) that are hierarchically ordered and syntactically and semantically correct. With the indexing algorithm, keys are computed such that concepts are partially unifiable with all more specific concepts and only semantically correct concepts are allowed to be added. The keys represent terminological relationships. Correctness and completeness of the underlying indexing algorithm are proven. The use of classical relational databases for the storage of instances is described. Because of the uniform representation, inference can be done using case-based reasoning and generic problem solving methods

Switching opioid-dependent patients in substitution treatment from racemic methadone, levomethadone and buprenorphine to slow-release oral morphine: Analysis of the switching process in routine care

Since 2015 slow-release oral morphine (SROM) is approved for opioid substitution treatment (OST) in Germany. The SROMOS study (efficacy and tolerability of slow-release oral morphine in opioid substitution treatment) evaluates the efficacy and safety of SROM in routine care. This article describes the switching process from racemic methadone, levomethadone and buprenorphine to SROM.Between July 2016 and November 2017 180 patients in 23 study centers in Germany were included in the prospective, non-interventional, naturalistic observational study. Patients were already in OST and switched from a previous medication to SROM. The switching process was analyzed during a period of fourteen days.Data were available for 169 participants. The switching process had a different progression depending on premedication and pre dosage. On the fourteenth day of SROM treatment patients switched from racemic methadone took an average dosage of 922.2 mg/day, from levomethadone 801.0 mg/day and from buprenorphine 626.7 mg/day. Average conversion ratio racemic methadone to SROM was 1:11.8, levomethadone to SROM 1:17.4 and buprenorphine to SROM 1:58.0.This study provides the first data on the switching process from buprenorphine to SROM. Average dose ratio racemic methadone to SROM on the fourteenth day of treatment was considerably higher than recommended in the prescribing information

The relationship of quality of life and distress in prostate cancer patients compared to the general population

Background: The aim of this study is two-fold. The first part compares quality of life (QoL) data of prostate cancer patients with those of a representative and age-specific sample of the general population and analyzes the influence of cancer related as well as socio-demographic parameters on QoL. Secondly, differences in QoL depending on the experienced psychological distress will be shown both in prostate cancer patients and in the general population

The dynamics of entrepreneurial ecosystems: an empirical investigation

The purpose of this paper is to examine the longitudinal dynamics within entrepreneurial ecosystems. We empirically test how entrepreneurial activities affect intrapreneurial activities within entrepreneurial ecosystems, and vice versa, analyzing twenty-two entrepreneurial ecosystems in Germany from 1993 to 2016. Our analyses reveal that transitions occur among entrepreneurs and intrapreneurs through the different phases of an ecosystem's lifecycle. Our findings provide empirical evidence over time on the evolutionary dynamics of entrepreneurial ecosystems, demonstrating that an increase in entrepreneurial activities leads to a decrease in intrapreneurial activities, and vice versa. Our study offers guidance for policymakers on how to consider fluctuating entrepreneurial and intrapreneurial activities over time and builds the basis for future empirical studies to further advance our understanding of the dynamics of entrepreneurial ecosystems

Endothelial Tissue-Type Plasminogen Activator Release in Coronary Heart Disease Transient Reduction in Endothelial Fibrinolytic Reserve in Patients With Unstable Angina Pectoris or Acute Myocardial Infarction

AbstractObjectives. We sought to examine whether the disturbed fibrinolytic system in patients with an acute coronary syndrome is associated with a reduced endothelial fibrinolytic capacity.Background. Intracoronary thrombus formation is a frequent finding in acute coronary syndromes. Systemic alterations of coagulation and fibrinolysis are known to occur, but possible disturbances of endothelial fibrinolytic function have not been investigated.Methods. We compared 42 patients with an acute coronary syndrome (acute myocardial infarction in 11 and unstable angina pectoris in 31) with 25 patients with stable angina. Venous blood was sampled serially for determination of markers of the fibrinolytic system and of hypercoagulability from admission to day 10. An occlusion test to determine the maximal endothelial tissue-type plasminogen activator (t-PA) release was also performed.Results. Both on day 0 and day 10, patients with an acute coronary syndrome had a marked elevation of t-PA mass concentration (mean value ± SEM 14.4 ± 1.6 [day 0], 18.9 ± 2.5 ng/ml [day 10]) and of plasminogen activator inhibitor (PAI) (9.4 ± 2.2 [day 0], 11.3 ± 2.6 AU/liter [day 10], p < 0.05 vs. patients with stable angina). There was also a hypercoagulative state with elevated thrombin activity and increased D-dimers (p < 0.05 vs. patients with stable angina). Maximal endothelial t-PA release was initially reduced (p < 0.05 vs. patients with stable angina) to 2.3 ± 0.9 ng/ml, but levels recovered during follow-up to 4.4 ± 1.4 ng/ml (vs. 5.7 ± 1.5 ng/ml in patients with stable angina).Conclusions. Despite the known prolonged systemic alteration of fibrinolysis in acute coronary syndromes, endothelial fibrinolytic capacity is reduced only during the acute phase and becomes normalized during follow-up, and thus is linked more to intravascular thrombus formation than to steady state levels of markers of the fibrinolytic system

Nanodrawing of aligned single carbon nanotubes with a nanopen

Single-walled carbon nanotubes (SWCNTs) are considered pivotal components for molecular electronics. Techniques for SWCNT lithography today lack simplicity, flexibility, and speed of direct, oriented deposition at specific target locations. In this paper SWCNTs are directly drawn and placed with chemical identification and demonstrated orientation using fountain pen nanolithography (FPN) under ambient conditions. Placement across specific electrical contacts with such alignment is demonstrated and characterized. The fundamental basis of the drawing process with alignment has potential applications for other related systems such as inorganic nanotubes, polymers, and biological molecules

Status of Micro-Hydrokinetic River Technology Turbines Application for Rural Electrification in Africa

Energy accessibility, reliability and availability are key components of improved quality of life and human development in all spheres. As the United Nations’ SDG 7 calls for access to electricity for all by 2030, Africa still has a wide gap to fill as the statistics show that 85% of the population that will not have access to electricity is in Africa. As the world tries to wean itself off non-renewable energy and transition to green through use of renewable energy sources, hydropower energy remains at the heart of Africa for this venture. With majority of the rural population in Africa lacking electricity, there is need for a low-tech system that utilizes river flow to generate just enough energy for normal operation in these regions. Micro-hydrokinetic river turbine technology (µ-HRT), which offers less intermittency, can potentially contribute to sustainably electrifying Africa rural areas. The technology has been adopted by few countries worldwide, with limited comprehensive study in Africa even though the technology seems viable for use in African rivers. This paper reviewed the status of the µ-HRT applications in Africa and some of the barriers to its development. The study found out that the technology has not been vastly developed in Africa. Despite numerous barriers, the technology is simply a low-tech technology that requires the use of local resources and capacity building for its sustainability in terms of construction, operation and maintenance requirements. It is therefore recommended that R&D and field trials be conducted for its possible adoption