Time filter

Source Type

Orange, CA, United States

Chapman University is a private, non-profit university located in Orange, California, affiliated with the Christian Church . Chapman University encompasses seven schools and colleges: Lawrence and Kristina Dodge College of Film and Media Arts, Wilkinson College of Humanities and Social science, George L. Argyros School of Business and Economics, Schmid College of Science & Technology, College of Performing Arts, Dale E. Fowler School of Law and College of Educational Studies. For the 2010–11 academic year, Chapman University enrolled 6,398 students. Wikipedia.

Allosteric interactions of the molecular chaperone Hsp90 with a large cohort of cochaperones and client proteins allow for molecular communication and event coupling in signal transduction networks. The integration of cochaperones into the Hsp90 system is driven by the regulatory mechanisms that modulate the progression of the ATPase cycle and control the recruitment of the Hsp90 clientele. In this work, we report the results of computational modeling of allosteric regulation in the Hsp90 complexes with the cochaperones p23 and Aha1. By integrating protein docking, biophysical simulations, modeling of allosteric communications, protein structure network analysis and the energy landscape theory we have investigated dynamics and stability of the Hsp90-p23 and Hsp90-Aha1 interactions in direct comparison with the extensive body of structural and functional experiments. The results have revealed that functional dynamics and allosteric interactions of Hsp90 can be selectively modulated by these cochaperones via specific targeting of the regulatory hinge regions that could restrict collective motions and stabilize specific chaperone conformations. The protein structure network parameters have quantified the effects of cochaperones on conformational stability of the Hsp90 complexes and identified dynamically stable communities of residues that can contribute to the strengthening of allosteric interactions. According to our results, p23-mediated changes in the Hsp90 interactions may provide "molecular brakes" that could slow down an efficient transmission of the inter-domain allosteric signals, consistent with the functional role of p23 in partially inhibiting the ATPase cycle. Unlike p23, Aha1-mediated acceleration of the Hsp90-ATPase cycle may be achieved via modulation of the equilibrium motions that facilitate allosteric changes favoring a closed dimerized form of Hsp90. The results of our study have shown that Aha1 and p23 can modulate the Hsp90-ATPase activity and direct the chaperone cycle by exerting the precise control over structural stability, global movements and allosteric communications in Hsp90.

Vickers C.P.,Chapman University
Aphasiology | Year: 2010

Background: Social networks are the context for communication and life participation and are associated with adults' health, well-being, and longevity. Compared to other populations, persons with aphasia have not been included in social network research in the US. Aims: The study aimed to measure and compare 40 participants' social networks and frequency of contact within networks before and after aphasia. It also examined self-ratings of communication/social participation as well as perceived social isolation versus perceived social support. A further aim was to explore the impact of weekly aphasia group attendance on all variables by comparing two groups within the sample: 28 persons attending a weekly aphasia group, and 12 persons not attending an aphasia group. Methods & Procedures: Social network interviews for social network analysis and questionnaire surveys measured the perceptions and experiences of a non-random sample of 40 persons with aphasia in the US. Measures included Social Networks Inventory (Blackstone & Hunt-Berg, 2003), The Friendship Scale (Hawthorne, 2006), and a pilot tool, The Survey of Communication and Social Participation (Vickers & Threats, 2007). Both descriptive and inferential statistics were used to explore the data and compare the aphasia group attendees (N = 28) with non-attendees (N = 12). Outcomes & Results: Results indicated shrinkage of social networks and reduced frequency of contact with partners after onset of aphasia for the entire group. Independent samples t tests revealed significantly higher levels of social participation, and significantly less perceived social isolation and greater social connection for the 28 individuals attending a weekly aphasia group. Conclusions: A major contribution of this study is its direct inclusion of 40 individuals with aphasia in a project in the US that provided quantitative data about social networks before and after aphasia. Results confirm that clinicians should be concerned about potential reduction of social networks and social isolation after aphasia. Data also support the notion of significantly increased social participation and sense of social connectedness for those who attend aphasia groups. The findings point to the need to directly assess aphasic individuals' social networks as the context for life participation through social network analysis. It also suggests that intervention efforts in aphasia therapy would be enhanced by assessing how persons with aphasia perceive their level of social connection as well as their participation in the social environment. © 2010 Psychology Press.

Jordan A.N.,University of Rochester | Jordan A.N.,Chapman University | Martinez-Rincon J.,University of Rochester | Howell J.C.,University of Rochester
Physical Review X | Year: 2014

The technical merits of weak-value-amplification techniques are analyzed. We consider models of several different types of technical noise in an optical context and show that weak-value-amplification techniques (which only use a small fraction of the photons) compare favorably with standard techniques (which use all of them). Using the Fisher-information metric, we demonstrate that weak-value techniques can put all of the Fisher information about the detected parameter into a small portion of the events and show how this fact alone gives technical advantages. We go on to consider a time-correlated noise model and find that a Fisher-information analysis indicates that the standard method can have much larger information about the detected parameter than the postselected technique. However, the estimator needed to gather the information is technically difficult to implement, showing that the inefficient (but practical) signal-to-noise estimation of the parameter is usually superior.We also describe other technical advantages unique to imaginary weak-value-amplification techniques, focusing on beam-deflection measurements. In this case, we discuss combined noise types (such as detector transverse jitter, angular beam jitter before the interferometer, and turbulence) for which the interferometric weak-value technique gives higher Fisher information over conventional methods. We go on to calculate the Fisher information of the recently proposed photon-recycling scheme for beam-deflection measurements and show it further boosts the Fisher information by the inverse postselection probability relative to the standard measurement case.

Agency: NSF | Branch: Standard Grant | Program: | Phase: Environmental Chemical Science | Award Amount: 270.00K | Year: 2016

In this project, funded by the Environmental Chemical Sciences Program in the Division of Chemistry at the National Science Foundation, Professor Christopher Kim of Chapman University is performing research that involves detailed characterization of iron oxyhydroxide nanoparticle aggregates. These characterization studies include batch and real-time metal ion adsorption/desorption experiments and synchrotron-based X-ray spectroscopic methods to improve predictive modeling of metal uptake/retention to nanoscale iron oxyhydroxides. Nanoparticles of inorganic mineral phases are widespread in water-based environmental systems. Natural and synthetic nanoparticles are highly effective in remediation strategies for contaminated waters, such as those that result from metal ore mining activities. This research develops models to predict metal fate and transport in natural waterways. These studies maximize metal retention and reduce metal mobility in contaminated systems. Broader impacts of this work include the creation of independent research opportunities for undergraduate, community college, and high school students (targeting females, under-represented minorities, and low-income populations), providing students with experiences using national synchrotron user facilities, and incorporating new findings in nanoparticle research to the undergraduate curricula in environmental and inorganic chemistry. High school chemistry and environmental science teachers are engaged in the research methods and outcomes through on-campus visits and lesson development.

The fate and speciation of metal ion species sorbed to aggregated nanoparticles are largely unknown. Metal sorption to nanoaggregates serves as an important means of natural attenuation and provides considerable potential for the effective remediation of metal-contaminated surface aqueous systems. Specifically, with increasing aggregation state, salinity, and time, metal uptake declines due to loss of reactive surface area but metal retention may increase due to trapping of sorbed ions onto/into the more complex confined aggregate structures. This project advances our understanding of the fundamental processes that control the retention and sequestration of metal ions onto nanoscale iron oxyhydroxide particles and their aggregates. The research impacts the emerging field of environmental nanoscience, particularly the role that nanoscale particles play in the remediation of metal-contaminated sites.

Agency: NSF | Branch: Standard Grant | Program: | Phase: CAREER: FACULTY EARLY CAR DEV | Award Amount: 519.75K | Year: 2015

The vision behind advanced cyberinfrastructure (CI) is that its development, acquisition, and provision will transform science and engineering in the 21st century. However, CI diffusion is full of challenges, because the adoption of the material objects also requires the adoption of a set of related behavioral practices and philosophical ideologies. Most critically, CI-enabled virtual organizations (VOs) often lack the full range of organizational capacity to effectively integrate and support the complex web of objects, practices, and ideologies as a holistic innovation.

This project examines the various manifestations of CI related objects, practices, and ideologies, and the ways they support CI implementation in scientific VOs. Using grounded theory analysis of interviews and factor analysis of survey data, this project will develop and validate a robust framework/measure of organizational capacity for CI diffusion. The projects empirical focus will be the NSF-funded Extreme Science and Engineering Discovery Environment (XSEDE; https://www.xsede.org/), a nationwide network of distributed high-performance computing resources. Interviews and surveys will solicit input from domain scientists, computational technologists, and supercomputer center administrators (across e-science projects, institutions, and disciplines) who have experience with adopting and using CI tools within the XSEDE ecosystem. The project will generate a series of capacity building strategies to help VOs increase the organizational capacity necessary to fully adopt CI. Findings will help NSF and other federal agencies to improve existing and future CI investments. This project may also have implications for open-source and commercial technologies that harness big data for complex simulations, modeling, and visualization analysis.

Discover hidden collaborations