Massively parallel computing on an organic molecular layer

Current computers operate at enormous speeds of ~10^13 bits/s, but their principle of sequential logic operation has remained unchanged since the 1950s. Though our brain is much slower on a per-neuron base (~10^3 firings/s), it is capable of remarkable decision-making based on the collective operations of millions of neurons at a time in ever-evolving neural circuitry. Here we use molecular switches to build an assembly where each molecule communicates-like neurons-with many neighbors simultaneously. The assembly's ability to reconfigure itself spontaneously for a new problem allows us to realize conventional computing constructs like logic gates and Voronoi decompositions, as well as to reproduce two natural phenomena: heat diffusion and the mutation of normal cells to cancer cells. This is a shift from the current static computing paradigm of serial bit-processing to a regime in which a large number of bits are processed in parallel in dynamically changing hardware.Comment: 25 pages, 6 figure

The Grizzly, January 30, 1987

U.C. Master Plan Features Art, Roads, Humanities Building • Aggressive Couple Sparks Conflicts and Challenges • Art Critic to Explain Sculpture • Letter: Abortion Issue\u27s Indefinite Life • Editorial: Silent Scream Meets U.C. Yawn • News Notes: Effectiveness Training Course Offered; Stress Management Workshops; Who\u27s Who at Ursinus?; Voice Workshop Offered; Enhance Self Presentation; Grammar and Writing Course • Jones Recalls Fetterolf of Yesteryear • Racich has Bears Rolling Toward MAC Riches • Bear Hoopsters Fall From First • Men Mers Rip Scranton in First Historical Meeting • Men\u27s Track Banking on Distance and Field • Gymnasts Open Semester With Split • Soccer\u27s Quinn a Standout • Swimmin\u27 Women Use Off-Season Workouts to Advantage at 3-3 • Odgers Makes Grade on and off Field • Davidson Assumes Presidency of PSAHPERD • Arthur Vining Davis Foundation Offers $60,000 to Support Residential Village • Development\u27s Randolph Introduces STAR Committee • Alderfer Takes Championship, Badminton Opens • Gall Finds the Way it is Fresh and New • Lionarons Leads Lecture • 1987 Class Chairmen Sought by Applicationhttps://digitalcommons.ursinus.edu/grizzlynews/1179/thumbnail.jp

Bias-voltage dependence of the magneto-resistance in ballistic vacuum tunneling: Theory and application to planar Co(0001) junctions

Motivated by first-principles results for jellium and by surface-barrier shapes that are typically used in electron spectroscopies, the bias voltage in ballistic vacuum tunneling is treated in a heuristic manner. The presented approach leads in particular to a parameterization of the tunnel-barrier shape, while retaining a first-principles description of the electrodes. The proposed tunnel barriers are applied to Co(0001) planar tunnel junctions. Besides discussing main aspects of the present scheme, we focus in particular on the absence of the zero-bias anomaly in vacuum tunneling.Comment: 19 pages with 8 figure

Neutral and Charged Polymers at Interfaces

Chain-like macromolecules (polymers) show characteristic adsorption properties due to their flexibility and internal degrees of freedom, when attracted to surfaces and interfaces. In this review we discuss concepts and features that are relevant to the adsorption of neutral and charged polymers at equilibrium, including the type of polymer/surface interaction, the solvent quality, the characteristics of the surface, and the polymer structure. We pay special attention to the case of charged polymers (polyelectrolytes) that have a special importance due to their water solubility. We present a summary of recent progress in this rapidly evolving field. Because many experimental studies are performed with rather stiff biopolymers, we discuss in detail the case of semi-flexible polymers in addition to flexible ones. We first review the behavior of neutral and charged chains in solution. Then, the adsorption of a single polymer chain is considered. Next, the adsorption and depletion processes in the many-chain case are reviewed. Profiles, changes in the surface tension and polymer surface excess are presented. Mean-field and corrections due to fluctuations and lateral correlations are discussed. The force of interaction between two adsorbed layers, which is important in understanding colloidal stability, is characterized. The behavior of grafted polymers is also reviewed, both for neutral and charged polymer brushes.Comment: a review: 130 pages, 30 ps figures; final form, added reference

Unpacking the impact of integrating the neglected tropical disease supply chain into the national supply chain system: illustrative evidence from Liberia

Effective supply chain management is a critical pillar of well-functioning health systems ensuring that medical commodities reach those in need. In Liberia, the national neglected tropical disease (NTD) programme supports health systems strengthening for case management of NTDs. Integration of NTD commodities into the national health system supply chain is central to the integrated approach; however, there is minimal evidence on enablers and barriers. Drawing on qualitative evaluation data, we illustrate that perceived benefits and strengths to integrating NTD commodities into the supply chain include leveraged storage and management capacities capitalized at lower system levels; the political will to integrate based on cost-saving and capacity strengthening potential and positive progress integrating paper-based reporting tools. Challenges remain, specifically the risk of reliance on donor funding; difficulty in accessing commodities due to bureaucratic bottlenecks; lack of inclusion of NTD commodities within electronic data tools and poor coordination leading to an inability to meet demand. Collectively, the negative consequences of ineffective integration of NTD commodities into the supply chain has a detrimental impact on health workers (including community health workers) unable to deliver the quality of care to patients. Trust between affected populations and the health system is compromised when treatments are unavailable

Executive Compensation, Corporate Governance and Corporate Performance: A Simultaneous Equation Approach

This paper investigates the association between executive compensation and performance. It uniquely utilises a comprehensive set of corporate governance mechanisms within a three-stage least squares (3SLS) simultaneous equation framework. Results based on estimating a conventional single equation model indicate that the executive pay and performance sensitivity is relatively weak, whereas those based on estimating a 3SLS model generally suggest improved executive pay and performance sensitivity. Our findings highlight the need for future research to control for possible simultaneous interdependencies when estimating the executive pay and performance link. The findings are generally robust across a raft of econometric models that control for different types of endogeneities, executive pay and performance proxies.<br/

Multimethod evaluation of health services integration for neglected tropical diseases requiring case management in Liberia.

Introduction The WHO neglected tropical disease (NTD) roadmap stresses the importance of integrating NTDs requiring case management (CM) within the health system. The NTDs programme of Liberia is among the first to implement an integrated approach and evaluate its impact. Methods A retrospective study of three of five CM-NTD-endemic counties that implemented the integrated approach was compared with cluster-matched counties with non-integrated CM-NTD. We compared trends in CM-NTD integrated versus non-integrated county clusters. We conducted a pre-post comparison of WHO high-level outcomes using data collected during intervention years compared with baseline in control counties. Changes in health outcomes, effect sizes for different diseases and rate ratios with statistically significant differences were determined. Complementary qualitative research explored CM-NTD stakeholders' perceptions, analysed through the framework approach, which is a transparent, multistage approach for qualitative thematic interdisciplinary data analysis. Results The detection rates for all diseases combined improved significantly in the intervention compared with the control clusters. Besides leprosy, detection rates improved with large effects, over fourfold increase with statistically significant effects for individual diseases. Conclusions Integrating CM-NTDs improves case detection, accessibility and availability of CM-NTD services, promoting universal health coverage. Early case detection and the quality of care need further strengthening