4,224 research outputs found

    Perils of the High and Low Roads: Employment Relations in the United States and Germany

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    [Excerpt] The U.S. crisis is characterized by growing income inequality, a shrinking safety net, and the decline of worker representation. Like the German crisis, it is caused in part by intensified global competition. Unlike in Germany, problems in the United States have also been exacerbated by deregulation, short-term horizons (e.g., quarterly reports to shareholders), and the decline of the labor movement. Both Germany and the United States, however, have substantial political, economic, and social resources to use in solving their problems. The contemporary crises do not appear for either of these countries to foreshadow a major collapse like that of the Great Depression. We are confident that actors in Germany and the United States can and will pursue reforms, including policy innovations and negotiation. In so doing, we suggest that these societies—the two strongest western economies—have a great deal to learn from each other and from their common experience in the global economy. They do not need, and are unlikely to get, convergence. Yet, each could benefit significantly by adopting elements and aspects of the other\u27s institutions, practices, and policies. In this chapter, the focus is on employment relations, which we believe are central to the broader economic and social problems in each society. We consider the following two interrelated questions. First, exactly how do the internal and external pressures on employment relations emerge in each country? Second, in what tangible forms do these pressures appear on the ground, where labor and business (and, more indirectly, other political, social, and economic actors) interact to perpetuate, alter, or scrap certain modes of production, including service delivery, work organization, and negotiation

    Proving Well-Definedness of JML Specifications with KeY

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    Specification methods in formal program verification enable the enhancement of source code with formal annotations as to formally specify the behaviour of a program. This is a popular way in order to subsequently prove software to be reliable and meet certain requirements, which is crucial for many applications and gains even more importance in modern society. The annotations can be taken as a contract, which then can be verified guaranteeing the specified program element – as a receiver – to fulfil this contract with its caller. However, these functional contracts can be problematic for partial functions, e.g., a division, as certain cases may be undefined, as in this example a division by zero. Modern programming languages such as Java handle undefined behaviour by casting an exception. There are several approaches to handle a potential undefinedness of specifications. In this thesis, we chose one which automatically generates formal proof obligations ensuring that undefined specification expressions will not be evaluated. Within this work, we elaborate on so-called Well-Definedness Checks dealing with undefinedness occurring in specifications of the modelling language JML/JML* in the KeY System, which is a formal software development tool providing mechanisms to deductively prove the before mentioned contracts. Advantages and delimitations are discussed and, furthermore, precise definitions as well as a fully functional implementation within KeY are given. Our work covers the major part of the specification elements currently supported by KeY, on the higher level including class invariants, model fields, method contracts, loop statements and block contracts. The process of checking the well-definedness of a specification forms a preliminary step before the actual proof and rejects undefined specifications. We further contribute by giving a choice between two different semantics, both bearing different advantages and disadvantages. The thesis also includes an extensive case study analysing many examples and measuring the performance of the implemented Well-Definedness Checks

    Formal Verification of Voting Schemes

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    Fundamental trust and credibility in democratic systems is commonly established through the existence and execution of democratic elections. The vote-counting of an election, usually formalised by a voting scheme, essentially boils down to a mechanism that aggregates individual preferences of the voters to reach a decision. For this matter, there are various differing voting schemes in use throughout the world, commonly based on high expectations and means to ensure a sensible democratic process. However, incidents such as the ruling by the German federal constitutional court which led to a change of the German legislation in 2013 manifest that it is difficult for a voting scheme to meet these legitimate expectations. In fact, there is no general notion of correctness for a voting scheme and thus no universal mechanism as shown in Kenneth J. Arrow’s Impossibility Theorem in 1951. As a consequence, designing a real-world voting scheme without flaws, which still gives significant democratic guarantees, is a difficult task as a trade-off between desirable properties is non-trivial and error-prone. The approach in this thesis is based on the idea to tackle this issue by proposing an incremental and iterative development process for voting schemes based on automated formal reasoning methods using program verification. We analyse two different forms of verification considering their role in this development process in order to achieve formal correctness of voting schemes. We perform a comprehensive set of case studies by applying ``medium-weight\u27\u27 and ``light-weight\u27\u27 verification techniques. The ``medium- weight\u27\u27 approach uses the annotation-based deductive verification tool VCC based on an auto-active methodology and the ``light-weight\u27\u27 technique is performed with the bounded model checking tool LLBMC. Our analysis covers a set of well-known voting schemes combined with a set of prominent voting scheme criteria. In addition to giving precise formalisations for these criteria adapted to the specific voting schemes and tools used, we advance the efficiency of the ``light-weight\u27\u27 approach by exploiting fundamental symmetric properties. Furthermore, we investigate on encountered challenges posed by the auto-active verification methodology, which lies in-between automatic and interactive verification methodologies, with respect to specific characteristics in voting schemes and also explore the potential of bounded verification techniques to produce precise counterexamples in order to enhance the capability of our envisioned development process to give early feedback. This thesis gives fundamental insights in general challenges and the potential of automated formal reasoning with the goal of correct voting schemes

    Formal Methods for Trustworthy Voting Systems : From Trusted Components to Reliable Software

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    Voting is prominently an important part of democratic societies, and its outcome may have a dramatic and broad impact on societal progress. Therefore, it is paramount that such a society has extensive trust in the electoral process, such that the system’s functioning is reliable and stable with respect to the expectations within society. Yet, with or without the use of modern technology, voting is full of algorithmic and security challenges, and the failure to address these challenges in a controlled manner may produce fundamental flaws in the voting system and potentially undermine critical societal aspects. In this thesis, we argue for a development process of voting systems that is rooted in and assisted by formal methods that produce transparently checkable evidence for the guarantees that the final system should provide so that it can be deemed trustworthy. The goal of this thesis is to advance the state of the art in formal methods that allow to systematically develop trustworthy voting systems that can be provenly verified. In the literature, voting systems are modeled in the following four comparatively separable and distinguishable layers: (1) the physical layer, (2) the computational layer, (3) the election layer, and (4) the human layer. Current research usually either mostly stays within one of those layers or lacks machine-checkable evidence, and consequently, trusted and understandable criteria often lack formally proven and checkable guarantees on software-level and vice versa. The contributions in this work are formal methods that fill in the trust gap between the principal election layer and the computational layer by a reliable translation of trusted and understandable criteria into trustworthy software. Thereby, we enable that executable procedures can be formally traced back and understood by election experts without the need for inspection on code level, and trust can be preserved to the trustworthy system. The works in this thesis all contribute to this end and consist in five distinct contributions, which are the following: (I) a method for the generation of secure card-based communication schemes, (II) a method for the synthesis of reliable tallying procedures, (III) a method for the efficient verification of reliable tallying procedures, (IV) a method for the computation of dependable election margins for reliable audits, (V) a case study about the security verification of the GI voter-anonymization software. These contributions span formal methods on illustrative examples for each of the three principal components, (1) voter-ballot box communication, (2) election method, and (3) election management, between the election layer and the computational layer. Within the first component, the voter-ballot box communication channel, we build a bridge from the communication channel to the cryptography scheme by automatically generating secure card-based schemes from a small formal model with a parameterization of the desired security requirements. For the second component, the election method, we build a bridge from the election method to the tallying procedure by (1) automatically synthesizing a runnable tallying procedure from the desired requirements given as properties that capture the desired intuitions or regulations of fairness considerations, (2) automatically generating either comprehensible arguments or bounded proofs to compare tallying procedures based on user-definable fairness properties, and (3) automatically computing concrete election margins for a given tallying procedure, the collected ballots, and the computed election result, that enable efficient election audits. Finally, for the third and final component, the election management system, we perform a case study and apply state-of-the-art verification technology to a real-world e-voting system that has been used for the annual elections of the German Informatics Society (GI – “Gesellschaft für Informatik”) in 2019. The case study consists in the formal implementation-level security verification that the voter identities are securely anonymized and the voters’ passwords cannot be leaked. The presented methods assist the systematic development and verification of provenly trustworthy voting systems across traditional layers, i.e., from the election layer to the computational layer. They all pursue the goal of making voting systems trustworthy by reliable and explainable formal requirements. We evaluate the devised methods on minimal card-based protocols that compute a secure AND function for two different decks of cards, a classical knock-out tournament and several Condorcet rules, various plurality, scoring, and Condorcet rules from the literature, the Danish national parliamentary elections in 2015, and a state-of-the-art electronic voting system that is used for the German Informatics Society’s annual elections in 2019 and following

    LAND AND ASSET SIZE, STRUCTURE AND DISTRIBUTION AND THE LINKS TO INCOME IN THREE DRYLANDS

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    At a late stage in preparing this work, we felt responding to the view of all partners that, before analyzing the consequences of asset situations for fertility, migration or environment, we should present, and to some extent explain, some facts about the size, composition, and distribution of assets for the three countries. This paper presents some general contextual evidence, and some main results for South Africa. Work is in progress in the India data, and will be undertaken later for Botswana.International Development,

    Long-Term Outcomes in Anterior Cruciate Ligament Reconstruction: A Systematic Review of Patellar Tendon Versus Hamstring Autografts.

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    BACKGROUND: Much controversy still exists surrounding graft choice in anterior cruciate ligament (ACL) reconstruction. Over the past decade, an increase in comparative studies with longer follow-up has enhanced our understanding of current graft options and outcomes. PURPOSE: To describe the long-term comparative outcomes of ACL reconstruction with autograft bone-patellar tendon-bone (BPTB) versus autograft hamstring (HS) ACL reconstruction with regard to clinical and radiographic outcomes. STUDY DESIGN: Systematic review; Level of evidence, 2. METHODS: A search of the PubMed, MEDLINE, Cochrane, and Scopus databases was performed to identify studies in the English language with outcome data comparing ACL reconstruction utilizing autograft BPTB and autograft HS; only studies with a minimum 5-year follow-up were included. Outcome data included failure and complications, manual and instrumented laxity, patient-reported outcomes, and radiographic risk of osteoarthritis. RESULTS: Twelve studies with a total of 953 patients met the inclusion criteria. Of these studies, 8 were level 1 evidence and 2 were level 2. Mean follow-up was 8.96 years (range, 5-15.3 years). No differences in graft failure or manual or instrumented laxity were seen in any studies. Lower clinical outcomes scores and greater motion loss were seen in BPTB patients in 1 and 2 studies, respectively. Two of 4 studies reporting on anterior knee pain, and 3 of 7 that recorded kneeling pain found it more frequently among BPTB patients. One study found significantly increased reoperation rates in HS patients, while another found a similar result in BPTB, and 1 study reported a significant increase in contralateral ACL tears in BPTB patients. Three of 5 studies reporting on radiographic evidence of osteoarthritis noted significantly increased rates in BPTB patients. CONCLUSION: This systematic review comparing long-term outcomes after ACL reconstruction with either autograft BPTB or autograft HS suggests no significant differences in manual/instrumented laxity and graft failures between graft types. An increase in long-term anterior knee pain, kneeling pain, and higher rates of osteoarthritis were noted with BPTB graft use

    Studies for a test procedure in video analysis with consumer cameras

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    Diese Bachelorarbeit zeigt auf, welche Probleme bei der Verwendung der Videofunktion von digitalen Consumer-Kameras wie Digitalkameras mit Videofunktion, Mobiltelefonen oder Camcordern entstehen können. Auf der Basis dieser Arbeit wird die Firma Image Engineering ein Testverfahren zur Videoanalyse entwickeln.This Bachelor thesis lists information about video errors including their technical backgrounds with consumer video devices such as digital cameras with a video mode, mobile phones or camcorders common in everyday life. On this base, the company Image Engineering will develop an appropriate test procedure

    Automatic Classification and Speaker Identification of African Elephant (\u3cem\u3eLoxodonta africana\u3c/em\u3e) Vocalizations

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    A hidden Markov model (HMM) system is presented for automatically classifying African elephant vocalizations. The development of the system is motivated by successful models from human speech analysis and recognition. Classification features include frequency-shifted Mel-frequency cepstral coefficients (MFCCs) and log energy, spectrally motivated features which are commonly used in human speech processing. Experiments, including vocalization type classification and speaker identification, are performed on vocalizations collected from captive elephants in a naturalistic environment. The system classified vocalizations with accuracies of 94.3% and 82.5% for type classification and speaker identification classification experiments, respectively. Classification accuracy, statistical significance tests on the model parameters, and qualitative analysis support the effectiveness and robustness of this approach for vocalization analysis in nonhuman species

    Alcohol consumption in heroin users, methadone-substituted and codeine-substituted patients - Frequency and correlates of use

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    This retrospective study aims to determine whether there is a difference in the additional consumption of alcohol between addicts treated with methadone or dihydrocodeine (DHC) and untreated addicts injecting heroin. 1,685 patients admitted for opioid withdrawal between 1991 and 1997 were reviewed. Cross-reference tables and multiple logistic regression analyses were carried out. 28% of patients take more than 40 g of alcohol daily (on average 176 g). We found that patients who are treated with methadone or DHC drink alcohol significantly more often daily than the heroin-dependent patients (p<0.01). Using multiple regression analyses, the results were confirmed. Additionally, we found that co-abuse of alcohol was predicted by male gender, longer duration of drug use, additional daily consumption of tetrahydrocannabinol and daily consumption of benzodiazepines. Alcohol consumption by opioid-addicted patients treated with methadone or DHC presents a serious medical problem. Co-abuse of alcohol will receive more attention Copyright (C) 2003 S. Karger AG, Basel
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