Solution-processed bilayer photovoltaic devices with nematic liquid crystals

The cross-linking of polymerisable liquid crystalline semiconductors is a promising approach to solution-processable, multilayer, organic photovoltaics. Here we demonstrate an organic bilayer photovoltaic with an insoluble electron-donating layer formed by cross-linking a nematic reactive mesogen. We investigate a range of perylene diimide (PDI) materials, some of which are liquid crystalline, as the overlying electron acceptor layer. We find that carrier mobility of the acceptor materials is enhanced by liquid crystallinity and that mobility limits the performance of photovoltaic devices. © 2013 © 2013 Taylor & Francis

Using Replication and Partitioning to Build Secure Distributed Systems

A challenging unsolved security problem is how to specify and enforce system-wide security policies; this problem is even more acute in distributed systems with mutual distrust. This paper describes a way to enforce policies for data confidentiality and integrity in such an environment. Programs annotated with security specifications are statically checked and then transformed by the compiler to run securely on a distributed system with untrusted hosts. The code and data of the computation are partitioned across the available hosts in accordance with the security specification. The key contribution is automatic replication of code and data to increase assurance of integrity—without harming confidentiality, and without placing undue trust in any host. The compiler automatically generates secure run-time protocols for communication among the replicated code partitions. Results are given from a prototype implementation applied to various distributed programs

Spin transfer switching of spin valve nanopillars using nanosecond pulsed currents

Spin valve nanopillars are reversed via the mechanism of spin momentum transfer using current pulses applied perpendicular to the film plane of the device. The applied pulses were varied in amplitude from 1.8 mA to 7.8 mA, and varied in duration within the range of 100 ps to 200 ns. The probability of device reversal is measured as a function of the pulse duration for each pulse amplitude. The reciprocal pulse duration required for 95% reversal probability is linearly related to the pulse current amplitude for currents exceeding 1.9 mA. For this device, 1.9 mA marks the crossover between dynamic reversal at larger currents and reversal by thermal activation for smaller currents

Forced Convective Diffusion and Interphase Heat and Mass Transfer: Computations of Radial Functions, Temperature and Concentration Fields, and Presentation of Local and Average Nusselt and Sherwood Numbers

Theoretical calculations have been carried out for forced convective transport for uniform streaming and uniaxial and biaxial extensional axisymmetric flows past single spheres. Homogeneous and heterogeneous chemical reactions, both of first and of second order have also been or are presently being treated. Orthogonality and other properties of Legendre functions have been used, together with introduction of an eigenfunction expansion, to reduce the mathematical description from a partial differential equation with variable coefficients, which is nonlinear for homogeneous second order chemical reactions, to a system of coupled ordinary differential equations for the radial modes. The numerical solutions of the latter have been obtained using the robust, adaptive grid algorithm of Pereyra and Lentini. Plots of the radial functions for given Peclet and Damkohler numbers give insight into the role and interaction of L and of r∞ (the number of terms necessary for convergence of the expansion and the finite radius at which the boundary conditions at infinity are imposed). From the radial modes, local and average Nusselt and Sherwood numbers, as well as the temperature and concentration fields, can be obtained. Plots of radial function families provide new insights that complement physicochemical understanding gained from isocontour plots of the temperature and concentration fields. Plots of local interphase transfer coefficients reflect the behavior of the flux field over the sphere surface and show how the average coefficients arise

No effect of New Zealand blackcurrant extract on recovery of muscle damage following running a half-marathon

New Zealand blackcurrant (NZBC) contains anthocyanins, known to moderate blood flow and display anti-inflammatory properties that may improve recovery from exercise-induced muscle damage. The authors examined whether NZBC extract supplementation enhances recovery from exercise-induced muscle damage after a half-marathon race. Following a randomized, double-blind, independent groups design, 20 (eight women) recreational runners (age 30 ± 6 years, height 1.73 ± 0.74 m, body mass 68.5 ± 7.8 kg, half-marathon finishing time 1:56:33 ± 0:18:08 hr:min:s) ingested either two 300-mg/day capsules of NZBC extract (CurraNZ™) or a visually matched placebo, for 7 days prior to and 2 days following a half-marathon. Countermovement jump performance variables, urine interleukin-6, and perceived muscle soreness and fatigue were measured pre, post, and at 24 and 48 hr after the half-marathon and analyzed using a mixed linear model with statistical significance set a priori at p  .05). Urine interleukin-6 increased 48-hr post-half-marathon in the NZBC group only (p  .05). Perceived muscle soreness and fatigue increased immediately post-half-marathon (p  .05). Supplementation with NZBC extract had no effect on the recovery of countermovement jump variables and perceptions of muscle soreness or fatigue following a half-marathon in recreational runners

Detection theory for accurate and non-invasive skin cancer diagnosis using dynamic thermal imaging

Skin cancer is the most common cancer in the United States with over 3.5M annual cases. Presently, visual inspection by a dermatologist has good sensitivity (\u3e 90%) but poor specificity (\u3c 10%), especially for melanoma, which leads to a high number of unnecessary biopsies. Here we use dynamic thermal imaging (DTI) to demonstrate a rapid, accurate and non-invasive imaging system for detection of skin cancer. In DTI, the lesion is cooled down and the thermal recovery is recorded using infrared imaging. The thermal recovery curves of the suspected lesions are then utilized in the context of continuous-time detection theory in order to define an optimal statistical decision rule such that the sensitivity of the algorithm is guaranteed to be at a maximum for every prescribed false-alarm probability. The proposed methodology was tested in a pilot study including 140 human subjects demonstrating a sensitivity in excess of 99% for a prescribed specificity in excess of 99% for detection of skin cancer. To the best of our knowledge, this is the highest reported accuracy for any non-invasive skin cancer diagnosis method

A survey of physician receptivity to molecular diagnostic testing and readiness to act on results for early-stage colon cancer patients.

BACKGROUND: We sought to assess physician interest in molecular prognosic testing for patients with early stage colon cancer, and identify factors associated with the likelihood of test adoption. METHODS: We identified physicians who care for patients with early-stage (pN0) colon cancer patients, mailed them a survey, and analyzed survey responses to assess clinician receptivity to the use of a new molecular test (GUCY2C) that identifies patients at risk for recurrence, and clinician readiness to act on abnormal test results. RESULTS: Of 104 eligible potential respondents, 41 completed and returned the survey. Among responding physicians, 56 % were receptive to using the new prognostic test. Multivariable analyses showed that physicians in academic medical centers were significantly more receptive to molecular test use than those in non-academic settings. Forty-one percent of respondents were ready to act on abnormal molecular test results. Physicians who viewed current staging methods as inaccurate and were confident in their capacity to incorporate molecular testing in practice were more likely to say they would act on abnormal test results. CONCLUSIONS: Physician receptivity to molecular diagnostic testing for early-stage colon cancer patients is likely to be influenced by practice setting and perceptions related to delivering quality care to patients. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01972737

Graphene formation on SiC substrates

Graphene layers were created on both C and Si faces of semi-insulating, on-axis, 4H- and 6H-SiC substrates. The process was performed under high vacuum (<10-4 mbar) in a commercial chemical vapor deposition SiC reactor. A method for H2 etching the on-axis sub-strates was developed to produce surface steps with heights of 0.5 nm on the Si-face and 1.0 to 1.5 nm on the C-face for each polytype. A process was developed to form graphene on the substrates immediately after H2 etching and Raman spectroscopy of these samples confirmed the formation of graphene. The morphology of the graphene is described. For both faces, the underlying substrate morphology was significantly modified during graphene formation; sur-face steps were up to 15 nm high and the uniform step morphology was sometimes lost. Mo-bilities and sheet carrier concentrations derived from Hall Effect measurements on large area (16 mm square) and small area (2 and 10 um square) samples are presented and shown to compare favorably to recent reports.Comment: European Conference on Silicon Carbide and Related Materials 2008 (ECSCRM '08), 4 pages, 4 figure