Modeling of oligomeric-state dependent spectral heterogeneity in the B875 light-harvesting complex of Rhodobacter sphaeroides by numerical simulation

A series of detergent-isolated light-harvesting 1 (LH1, B875) complexes from Rhodobacter sphaeroides, estimated to range in size from (RâBChl2)4 to (RâBChl2)13, was used to study the combined effects of spectral disorder and excitonic interactions on oligomeric-state dependent optical properties. Numerical simulations of absorption and fluorescence emission, excitation, and polarization spectra, based on the structure of the related LH2 complex, were compared to spectra measured experimentally at 77 K (Westerhuis and Niederman, in preparation). The aggregation-state dependence of the polarization spectra was found to be particularly sensitive to the choice of parameters, and vibronic components were included to obtain satisfactory simulations. Good agreement with most experimental features, including the oligomeric-state dependence of the absorption and emission maxima, was obtained only when the inter- and intradimer coupling strengths for adjacent BChls were similar (200-260 cm-1), and the width for the inhomogeneous distribution function (300-400 cm-1) was comparable. The relevance of these findings to existing controversies on the physical origin of spectral heterogeneity observed for the LH1 complex is discussed

Research Agenda for Studying Open Source II: View Through the Lens of Referent Discipline Theories

In a companion paper [Niederman et al., 2006] we presented a multi-level research agenda for studying information systems using open source software. This paper examines open source in terms of MIS and referent discipline theories that are the base needed for rigorous study of the research agenda

A Research Agenda for Studying Open Source I: A Multi-Level Framework

This paper presents a research agenda for studying information systems using open source software A multi-level research model is developed at five discrete levels of analysis: (1) the artifact; (2) the individual; (3) the team, project, and community; (4) the organization; and (5) society. Each level is discussed in terms of key issues within the level. Examples are based on prior research. In a companion paper, [Niederman, et al 2006], we view the agenda through the lens of referent discipline theories

Pandemic Considerations on Essential Oral Health Care

The coronavirus disease 2019 (COVID-19) pandemic revealed a lack of consensus on the concept of essential oral health care. We propose a definition of essential oral health care that includes urgent and basic oral health care to initiate a broader debate and stakeholder alignment. We argue that oral health care must be part of essential health care provided by any health system. Essential oral health care covers the most prevalent oral health problems through an agreed-on set of safe, quality, and cost-effective interventions at the individual and community level to promote and protect oral health, as well as prevent and treat common oral diseases, including appropriate rehabilitative services, thereby maintaining health, productivity, and quality of life. By default, essential oral health care does not include the full spectrum of possible interventions that contemporary dentistry can provide. On the basis of this definition, we conceptualize a layered model of essential oral health care that integrates urgent and basic oral health care, as well as advanced/specialist oral health care. Finally, we present 3 key reflections on the essentiality of oral health care. First, oral health care must be an integral component of a health care system's essential services, and by implication, oral health care personnel are part of the essential health care workforce. Second, not all dental care is essential oral health care, and not all essential care is also urgent, particularly under the specific risk conditions of the pandemic. Third, there is a need for criteria, evidence, and consensus-building processes to define which dental interventions are to be included in which category of essential oral health care. All stakeholders, including the research, academic, and clinical communities, as well as professional organizations and civil society, need to tackle this aspect in a concerted effort. Such consensus will be crucial for dentistry in view of the Sustainable Development Goal's push for universal health coverage, which must cover essential oral health care

Stability transitions for axisymmetric relative equilibria of Euclidean symmetric Hamiltonian systems

In the presence of noncompact symmetry, the stability of relative equilibria under momentum-preserving perturbations does not generally imply robust stability under momentum-changing perturbations. For axisymmetric relative equilibria of Hamiltonian systems with Euclidean symmetry, we investigate different mechanisms of stability: stability by energy-momentum confinement, KAM, and Nekhoroshev stability, and we explain the transitions between these. We apply our results to the Kirchhoff model for the motion of an axisymmetric underwater vehicle, and we numerically study dissipation induced instability of KAM stable relative equilibria for this system.Comment: Minor revisions. Typographical errors correcte

Towards a Greater Diversity of Replication Studies

The replication of existing knowledge (e.g., previous study results) stands as an essential research practice across all science disciplines. Despite the importance of replication, the scarcity of replication studies is commonly criticized in business, management, and information system (IS) research. Therefore, efforts have already been made to facilitate replication research in the IS community, such as establishing conference tracks and journals focusing on publishing replication studies and providing guidelines on how and why to conduct replication research. Nonetheless, the perception of replication research remains unchanged, describing it as mundane. Therefore, in this issues and opinions article, we will explore how replication research could be made more appealing by diversifying the categories of replication studies. In this regard, we looked at replication in neuroscience, eliciting two new replication study categories: ‘transfer’ and ‘method.’ Additionally, through extensive discussion with other IS scholars, we added one more replication category, ‘comparison.’ We hope that this diversification will attract more researchers and also show the potential replication research holds

Factors Influencing the Green House Gas Footprint of US Dairy Farms

Environmental Economics and Policy, Livestock Production/Industries,

Electronic Pedagogy and Future University Business Models

Based on the International Conference on Information Systems’ (ICIS) 2014 senior scholars’ forum, we share insights on the relationship between evolving university business models and the adoption of electronic pedagogy. In recent years, particularly with the initiation of MOOCs, the potential for delivering high-quality and widely distributed coursework has expanded. However, particular instances of MOOCs and other electronic pedagogies do not guarantee equally high-quality educational outcomes for all participants. For example, some studies have suggested that most individuals completing MOOC coursework already have baccalaureate degrees, which contrasts with the idea that individuals undertake such coursework as a substitute for traditional degree programs. With this paper, we present varied experiences and views on using electronic pedagogy and report on both the conclusions and new questions raised about adopting these technologies for universities

Double exponential stability of quasi-periodic motion in Hamiltonian systems

We prove that generically, both in a topological and measure-theoretical sense, an invariant Lagrangian Diophantine torus of a Hamiltonian system is doubly exponentially stable in the sense that nearby solutions remain close to the torus for an interval of time which is doubly exponentially large with respect to the inverse of the distance to the torus. We also prove that for an arbitrary small perturbation of a generic integrable Hamiltonian system, there is a set of almost full positive Lebesgue measure of KAM tori which are doubly exponentially stable. Our results hold true for real-analytic but more generally for Gevrey smooth systems