Molecular dynamics study of MscL interactions with a curved lipid bilayer

Mechanosensitivity is a ubiquitous sensory mechanism found in living organisms. The simplest known mechanotransducing mechanism is found in bacteria in the form of the mechanosensitive membrane channel of large conductance, MscL. This channel has been studied extensively using a variety of methods at a functional and structural level. The channel is gated by membrane tension in the lipid bilayer alone. It serves as a safety valve protecting bacterial cells against hypoosmotic shock. MscL of Escherichia coli embedded in bilayers composed of asymmetric amounts of single-tailed and double-tailed lipids has been shown to gate spontaneously, even in the absence of membrane tension. To gain insight into the effect of the lipid membrane composition and geometry on MscL structure, a fully solvated, all-atom model of MscL in a stress-free curved bilayer composed of double- and single-tailed lipids was studied using a 9.5-ns molecular dynamics simulation. The bilayer was modeled as a domed structure accommodating the asymmetric composition of the monolayers. During the course of the simulation a spontaneous restructuring of the periplasmic loops occurred, leading to interactions between one of the loops and phospholipid headgroups. Previous experimental studies of the role of the loops agree with the observation that opening starts with a restructuring of the periplasmic loop, suggesting an effect of the curved bilayer. Because of limited resources, only one simulation of the large system was performed. However, the results obtained suggest that through the geometry and composition of the bilayer the protein structure can be affected even on short timescales.

Using system dynamics in a discrete-event simulation study of a manufacturing plant

Purpose - To provide an example of the use of system dynamics within the context of a discrete-event simulation study. Design/methodology/approach - A discrete-event simulation study of a production-planning facility in a gas cylinder-manufacturing plant is presented. The case study evidence incorporates questionnaire responses from sales managers involved in the order-scheduling process. Findings - As the project progressed it became clear that, although the discrete-event simulation would meet the objectives of the study in a technical sense, the organizational problem of "delivery performance" would not be solved by the discrete-event simulation study alone. The case shows how the qualitative outcomes of the discrete-event simulation study led to an analysis using the system dynamics technique. The system dynamics technique was able to model the decision-makers in the sales and production process and provide a deeper understanding of the performance of the system. Research limitations/implications - The case study describes a traditional discrete-event simulation study which incorporated an unplanned investigation using system dynamics. Further, case studies using a planned approach to showing consideration of organizational issues in discrete-event simulation studies are required. Then the role of both qualitative data in a discrete-event simulation study and the use of supplementary tools which incorporate organizational aspects may help generate a methodology for discrete-event simulation that incorporates human aspects and so improve its relevance for decision making. Practical implications - It is argued that system dynamics can provide a useful addition to the toolkit of the discrete-event simulation practitioner in helping them incorporate a human aspect in their analysis. Originality/value - Helps decision makers gain a broader perspective on the tools available to them by showing the use of system dynamics to supplement the use of discrete-event simulation. © Emerald Group Publishing Limited.

Molecular dynamics study of solvent transport in nanoscale osmosis

An ideal of osmotic equilibrium between an ideal solution and pure solvent separated by a semi-permeable membrane is studied numerically using the method of molecular dynamics. The osmotic flow is observed as the inflow of the solvent across the membrane from the dilute to the concentrated side. The validity of van't Hoff's law for osmotic pressure is confirmed over a wide range of concentrations. It is found that the law is established by a balance between non-uniform partial pressures of solute and solvent. Furthermore, the present model permits an understanding of the mechanism of the osmotic flow in the relaxation process as the liquids evolve from the initial state to the equilibrium state. We focus in particular on the interaction between solute and solvent. ©2008 The Physical Society of Japan.

The atypical bilingual courtroom:an exploratory study of the interactional dynamics in interpreter-mediated trials in Hong Kong

This study investigates the communication process in the atypical bilingual Hong Kong courtroom, where, unlike in most other jurisdictions, interpreting services are routinely provided for the linguistic majority instead of the linguistic minority and the interpreter usually has to work with court actors who share his/her bilingual knowledge. It sets out to explore how the unique nature of the bilingual Hong Kong courtroom impacts on interactional dynamics in communicative process in the courtroom and potentially on the administration of justice, using authentic recordings of nine criminal trials from three court levels, supplemented by a survey administered to court interpreters. It compares the participant roles of different court actors in different court settings, monolingual and bilingual, using Goffman’s (1981) participation framework and Bell’s (1984) audience design as the conceptual framework. It is found that the notion of recipientship in the atypical bilingual Hong Kong courtroom is complicated by the presence of other bilinguals, which inevitably changes the interactional dynamics and impacts on the power of court interpreter as these bilinguals take on more participant roles in the process. The findings of this study show that the power of court actors is realised in the participant role(s) they and the other co-present court actors take on or are capable of playing. The findings also indicate that a change in the participant role of a court actor has an impact on the participation status other actors, which may in turn hamper the administration of justice. It is also found that the notion of power asymmetry in the courtroom has an effect on the footings adopted by the interpreter and thus on his/her neutrality. This thesis identifies training needs and makes recommendations for best practice in the courtroom and for institutional administrative practice.

Understanding dynamics of strategic decision-making in venture creation:a process study of effectuation and causation

This study draws upon effectuation and causation as examples of planning-based and flexible decision-making logics, and investigates dynamics in the use of both logics. The study applies a longitudinal process research approach to investigate strategic decision-making in new venture creation over time. Combining qualitative and quantitative methods, we analyze 385 decision events across nine technology-based ventures. Our observations suggest a hybrid perspective on strategic decision-making, demonstrating how effectuation and causation logics are combined, and how entrepreneurs’ emphasis on these logics shifts and re-shifts over time. We induce a dynamic model which extends the literature on strategic decision-making in venture creation.

Networks, space and organisational performance:a study of the determinants of industrial research income generation by universities

This paper examines the extent to which both network structure and spatial factors impact on the organizational performance of universities as measured by the generation of industrial research income. Drawing on data concerning the interactions of universities in the UK with large research and development (R&D)-intensive firms, the paper employs both social network analysis and regression analysis. It is found that the structural position of a university within networks with large R&D-intensive firms is significantly associated with the level of research income gained from industry. Spatial factors, on the other hand, are not found to be clearly associated with performance, suggesting that universities operate on a level playing field across regional environments once other factors are controlled for.

Seasonal dynamics of an aquatic macroinvertebrate assembly (Hydrobiological case study of Lake Balaton No. 2)

In 2002, 2003 and 2004, we took macoinvertebrate samples on a total of 36 occasions at the Badacsony bay of Lake Balaton. Our sampling site was characterised by areas of open water (in 2003 and 2004 full of reed-grass) as well as by areas covered by common reed (Phragmites australis) and narrowleaf cattail (Typha angustifolia). Samples were taken both from water body and benthic ooze by use of a stiff hand net. We have gained our data from processing 208 individual samples. We took samples frequently from early spring until late autumn for a deeper understanding of the processes of seasonal dynamics. The main seasonal patterns and temporal changes of diversity were described. We constructed a weather-dependent simulation model of the processes of seasonal dynamics in the interest of a possible further utilization of our data in climate change research. We described the total number of individuals, biovolume and diversity of all macroinvertebrate species with a single index and used the temporal trends of this index for simulation modelling. Our discrete deterministic model includes only the impact of temperature, other interactions might only appear concealed. Running the model for different climate change scenarios it became possible to estimate conditions for the 2070-2100 period. The results, however, should be treated very prudently not only because our model is very simple but also because the scenarios are the results of different models.

A study of leadership behaviors for Breaking Ranks leaders in public secondary schools

This research will investigate what it will take to develop principals who will embrace the recommendations of reform as proposed by National Association of Secondary School Principals (NASSP, 1996) in the Breaking Ranks document. Breaking Ranks is based on the belief that it is within the dynamics of the school culture that principals must gain insight into strategies for improving the schools for which they are held responsible. Given this context, it is important to examine perspectives that are held by principals who lead schools that embrace the concepts of reform as proposed by NASSP, thereby, could be deemed “Breaking Ranks” schools. It is within these schools that the new role of the principal develops. NASSP has identified seven key recommendations for leadership development; “attributes that need nourishing” (p. 12) for the success of school reform. The seven recommendations are included in Breaking Ranks. ^ The purpose of this study is to identify and describe how principals put the seven recommendations into practice as they function in their schools. In addition, this study will gather information on the characteristics, support, skills, and training these principals identify as critical aspects and components of their success. This is a study of principal leadership at four high school sites where “Breaking Ranks” principals have been identified. ^ This research plan will be designed to utilize an inquiry-based process with a panel of experts and four “Breaking Ranks” principals. This study will describe: (1) how a panel of experts identify what they believe needs to be done in order to put the recommendations of the Breaking Ranks document into practice and their identification of principals who are breaking ranks; (2) how identified principals say they have been able to put the recommendations of the Breaking Ranks document into practice; (3) How both groups identify and describe: (a) the characteristics and behaviors of a “Breaking Ranks” principal; (b) the new leadership skills as described by the seven recommendations identified in the Breaking Ranks document; (c) the support necessary in order to meet the recommendations in the Breaking Ranks document; and (d) The training needed in order to become “Breaking Ranks” principals; and (4) how the process of creating “Breaking Ranks” principals can be described by experts who have studied it theoretically and principals who have demonstrated it in their schools. ^

The Role of Corals on Tsunami Dynamics in an Island Setting: A Case Study of Tutuila Island

Thesis (Ph.D.)--University of Washington, 2016-07

A predictive computational fluid dynamics study of carotid artery

Abstract not available

A computational fluid dynamics study of the stencil printing process

Abstract not available