86 research outputs found
FEAST fundamental framework for electronic structure calculations: Reformulation and solution of the muffin-tin problem
In a recent article [1], the FEAST algorithm has been presented as a general
purpose eigenvalue solver which is ideally suited for addressing the numerical
challenges in electronic structure calculations. Here, FEAST is presented
beyond the "black-box" solver as a fundamental modeling framework which can
naturally address the original numerical complexity of the electronic structure
problem as formulated by Slater in 1937 [2]. The non-linear eigenvalue problem
arising from the muffin-tin decomposition of the real-space domain is first
derived and then reformulated to be solved exactly within the FEAST framework.
This new framework is presented as a fundamental and practical solution for
performing both accurate and scalable electronic structure calculations,
bypassing the various issues of using traditional approaches such as
linearization and pseudopotential techniques. A finite element implementation
of this FEAST framework along with simulation results for various molecular
systems are also presented and discussed.Comment: 20 pages, 7 figure
On the preconditions for large-scale collective action
The phenomenon of collective action and the origin of collective action problems have been extensively and systematically studied in the social sciences. Yet, while we have substantial knowledge about the factors promoting collective action at the local level, we know far less about how these insights travel to large-scale collective action problems. Such problems, however, are at the heart of humanity’s most pressing challenges, including climate change, large-scale natural resource depletion, biodiversity loss, nuclear proliferation, antibiotic resistance due to overconsumption of antibiotics, and pollution. In this paper, we suggest an analytical framework that captures the theoretical understanding of preconditions for large-scale collective action. This analytical framework aims at supporting future empirical analyses of how to cope with and overcome larger-scale collective action problems. More specifically, we (i) define and describe the main characteristics of a large-scale collective action problem and (ii) explain why voluntary and, in particular, spontaneous large-scale collective action among individual actors becomes more improbable as the collective action problem becomes larger, thus demanding interventions by an external authority (a third party) for such action to be generated. Based on this, we (iii) outline an analytical framework that illustrates the connection between third-party interventions and large-scale collective action. We conclude by suggesting avenues for future research.</p
Towards Harmonizing Multiple Architecture Description Languages for Real-Time Embedded Systems
Abstract-The increasing complexity of real-time embedded systems requires appropriate methods and techniques to support the development including the specification and analysis of different architectural aspects. A large number of architectural description languages (ADL) have been proposed with varying focus and application domains. There is a need for harmonization of these ADLs. This can be from develoloping and understanding of how they differ or could be synergistically combined for increasing the overall development efficiency and fulfilling the ever increasing functional and non-functional requirements on a system. This paper addresses this issue and focuses on four different ADLs: EAST-ADL, AUTOSAR, AADL and Rubus. In this work we compare these ADLs, identify possible usage scenarios involving more than one ADL and discuss some of the underlying challenges. A representative industrial case study of a brake-by-wire system is used to support the work
Three necessary conditions for establishing effective sustainable development goals in the Anthropocene
The purpose of the United Nations-guided process to establish Sustainable Development Goals is to galvanize governments and civil society to rise to the interlinked environmental, societal, and economic challenges we face in the Anthropocene. We argue that the process of setting Sustainable Development Goals should take three key aspects into consideration. First, it should embrace an integrated social-ecological system perspective and acknowledge the key dynamics that such systems entail, including the role of ecosystems in sustaining human wellbeing, multiple cross-scale interactions, and uncertain thresholds. Second, the process needs to address trade-offs between the ambition of goals and the feasibility in reaching them, recognizing biophysical, social, and political constraints. Third, the goal-setting exercise and the management of goal implementation need to be guided by existing knowledge about the principles, dynamics, and constraints of social change processes at all scales, from the individual to the global. Combining these three aspects will increase the chances of establishing and achieving effective Sustainable Development Goals
Characterization of lethal inhalational infection with Francisella tularensis in the common marmoset (Callithrix jacchus)
The intracellular Gram-negative pathogen Francisella tularensis is the causative agent of tularaemia and is prevalent in many countries in the northern hemisphere. To determine whether the common marmoset (Callithrix jacchus) would be a suitable non-human primate model of inhalational tularaemia, a pathophysiology study was undertaken. Ten animals were challenged with ∼102 c.f.u. F. tularensis strain SCHU S4 (F. tularensis subsp. tularensis). To look for trends in the infection, pairs of animals were sacrificed at 24 h intervals between 0 and 96 h post-challenge and blood and organs were assessed for bacteriology, pathology and haematological and immunological parameters. The first indication of infection was a raised core temperature at 3 days post-challenge. This coincided with a number of other factors: a rapid increase in the number of bacteria isolated from all organs, more pronounced gross pathology and histopathology, and an increase in the immunological response. As the disease progressed, higher bacterial and cytokine levels were detected. More extensive pathology was observed, with multifocal lesions seen in the lungs, liver and spleen. Disease progression in the common marmoset appears to be consistent with human clinical and pathological features of tularaemia, indicating that this may be a suitable animal model for the investigation of novel medical interventions such as vaccines or therapeutics
A Novel Approach to Determining Violence Risk in Schizophrenia: Developing a Stepped Strategy in 13,806 Discharged Patients
Clinical guidelines recommend that violence risk be assessed in schizophrenia. Current approaches are resource-intensive as they employ detailed clinical assessments of dangerousness for most patients. An alternative approach would be to first screen out patients at very low risk of future violence prior to more costly and time-consuming assessments. In order to implement such a stepped strategy, we developed a simple tool to screen out individuals with schizophrenia at very low risk of violent offending. We merged high quality Swedish national registers containing information on psychiatric diagnoses, socio-demographic factors, and violent crime. A cohort of 13,806 individuals with hospital discharge diagnoses of schizophrenia was identified and followed for up to 33 years for violent crime. Cox regression was used to determine risk factors for violent crime and construct the screening tool, the predictive validity of which was measured using four outcome statistics. The instrument was calibrated on 6,903 participants and cross-validated using three independent replication samples of 2,301 participants each. Regression analyses resulted in a tool composed of five items: male sex, previous criminal conviction, young age at assessment, comorbid alcohol abuse, and comorbid drug abuse. At 5 years after discharge, the instrument had a negative predictive value of 0.99 (95% CI = 0.98–0.99), meaning that very few individuals who the tool screened out (n = 2,359 out of original sample of 6,903) were subsequently convicted of a violent offence. Screening out patients who are at very low risk of violence prior to more detailed clinical assessment may assist the risk assessment process in schizophrenia
Government Structurs and Behavior Change in the Politics of HIV/AIDS
During the past decades, the worldwide spread of the human immuno-deficiency virus (HIV) has created one of the deadliest epidemics in human history. Despite widely available bio-medical knowledge about how to prevent transmission of the virus, and technologies and resources to treat people living with HIV/AIDS, the disease continues to spread, and especially in sub-Saharan Africa. However, despite the general precarious situation in sub-Saharan Africa, there is in fact great variation among African states as regards HIV prevalence. This paper builds a framework for increasing our understanding of the sources of this variation. More specifically, we argue that HIV/AIDS is a different kind of problem than other diseases in the sense that effective prevention demands sacrifices on the behalf of individuals that are costly in both material and non-material terms. The failure to recognize these costs makes standard solutions, such as for example increased access to medication, expanded funds, and health sector reforms, potentially ineffective. With the point of departure in the costs and individual sacrifices demanded for the successful combating of HIV/AIDS, this paper suggests that future research on HIV/AIDS would benefit from exploring the impact of varying institutional arrangements such as for example the degree to which state power is centralized or decentralized on HIV/AIDS outcomes. Institutions have commonly been argued to shape and constrain individual behavior. Yet, their impact on sexual behavior and behavior change remains largely unexplored
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