Thermochemical tests on resins: Char resistance of selected phenolic cured epoxides

Curing epoxy resins with novalac phenolic resins is a feasible approach for increasing intact char of the resin system. Char yields above 40% at 700 C were achieved with epoxy novalac (DEN 438)/novalac phenolic (BRWE 5833) resin systems with or without catalyst such as ethyl tri-phenyl phosphonium iodide. These char yields are comparable to commercially used epoxy resin systems like MY-720/DDS/BF3. Stable prepregs are easily made from a solvent solution of the epoxy/phenolic system and this provides a feasible process for fabrication of same into commercial laminates

Formulation and Characterization of Epoxy Resin Copolymer for Graphite Composites

Maximum char yield was obtained with a copolymer containing 25% mol fraction DGEBE and 75% mol fraction DGEBA (Epon 828). To achieve the high values (above 40%), a large quantity of catalyst (trimethoxyboroxine) was necessary. Although a graphite laminate 1/8" thick was successfully fabricated, the limited life of the catalyzed epoxy copolymer system precludes commercial application. Char yields of 45% can be achieved with phenolic cured epoxy systems as indicated by data generated under NAS2-10207 contract. A graphite laminate using this type of resin system was fabricated for comparison purposes. The resultant laminate was easier to process and because the graphite prepreg is more stable, the fabrication process could readily be adapted to commercial applications

On Estimating the High-Energy Cutoff in the X-ray Spectra of Black Holes via Reflection Spectroscopy

The fundamental parameters describing the coronal spectrum of an accreting black hole are the slope $\Gamma$ of the power-law continuum and the energy $E_{cut}$ at which it rolls over. Remarkably, this parameter can be accurately measured for values as high as 1 MeV by modeling the spectrum of X-rays reflected from a black hole accretion disk at energies below 100 keV. This is possible because the details in the reflection spectrum, rich in fluorescent lines and other atomic features, are very sensitive to the spectral shape of the hardest coronal radiation illuminating the disk. We show that fitting simultaneous NuSTAR (3-79 keV) and low-energy (e.g., Suzaku) data with the most recent version of our reflection model RELXILL, one can obtain reasonable constraints on $E_{cut}$ at energies from tens of keV up to 1 MeV, for a source as faint as 1 mCrab in a 100 ks observation.Comment: Accepted for publication in ApJL, 6 pages, 5 figure

Topological bands in two-dimensional networks of metamaterial elements

We show that topological frequency band structures emerge in two-dimensional electromagnetic lattices of metamaterial components without the application of an external magnetic field. The topological nature of the band structure manifests itself by the occurrence of exceptional points in the band structure or by the emergence of one-way guided modes. Based on an EM network with nearly flat frequency bands of nontrivial topology, we propose a coupled-cavity lattice made of superconducting transmission lines and cavity QED components which is described by the Janes-Cummings-Hubbard model and can serve as simulator of the fractional quantum Hall effect

Planning For Your Second Accounting Job

For many accounting students the focus of their fourth or fifth years is finding a job to start them on an exciting and financially rewarding career. Colleges provide significant guidance and direction to these students in the form of internship assistance, resume writing workshops, interview practice, networking events and career guidance. At most campuses public accounting firms are the most visible representative’s students encounter and these firms provide many students their internship and first full-time opportunities. Since Colleges strive to meet the needs of their customers much of the Career Planning focus is on public accounting and certification as a CPA. However, most students are faced with careers that span 40 years or more and few new graduates spend an entire career with their first employer. At some point they find themselves in the job market because of a desire to relocate, to pursue better opportunities, to achieve a better work/life balance or because of corporate reorganizations. Being in the job market with the wrong set of credentials will limit an individuals employment opportunities and lengthen the time required to find an appropriate job. To get a sense of the skills that may be in demand in the future it is helpful to know the degrees and certifications employers are looking for today. Using the on-line job search data bases in four major markets (New York City, Dallas, Los Angeles and Denver) we tabulated the credentials and advanced degrees most often referenced in employment advertisements. These four markets are each serviced by a major newspaper that provides job seekers with free on-line access to jobs advertised in their paper. In addition, these cities are located in states that have implemented the 150 hour requirement (New York and Texas) and in states that have not yet implemented the 150 hour requirement (Colorado and California). The search results can serve as a guide for students and educators who want to be aware of the most sought after credentials and certifications in the current job market. This information may be useful in curriculum decisions and career planning guidance. Information on the most sought after certifications including links to the organization that sponsors the certification, requirements of certification and experience and continuing education requirements is also provided

Action-derived molecular dynamics in the study of rare events

We present a practical method to generate classical trajectories with fixed initial and final boundary conditions. Our method is based on the minimization of a suitably defined discretized action. The method finds its most natural application in the study of rare events. Its capabilities are illustrated by non-trivial examples. The algorithm lends itself to straightforward parallelization, and when combined with molecular dynamics (MD) it promises to offer a powerful tool for the study of chemical reactions.Comment: 7 Pages, 4 Figures (3 in color), submitted to Phys. Rev. Let

Predictors of Health-related Quality of Life at One Month after Head and Neck Cancer Surgery

poster abstractSignificance: Head and neck cancer (HNC) survivors frequently experience treatment-related complications that may cause decrements in health-related quality of life (HRQOL). Before interventions can be designed to enhance HRQOL in the early postoperative period, descriptive research is needed to determine predictors of HRQOL in this understudied population. Problem and Purpose: The proposed study identified predictors of global HRQOL, and physical, functional, emotional, and social well-being at one month after HNC surgery. Variables examined as potential predictors included shoulder pain, shoulder function, and functional impairments (disfigurement, and eating, speech, and breathing impairments). Theoretical Framework: The University of California, San Francisco School of Nursing Symptom Management Model was modified and used to guide the study. Methods and Analysis: In this exploratory, cross-sectional study, we examined a convenience sample of 29 patients who had undergone HNC surgery with curative intent one month previously. Global HRQOL was measured using the Functional Assessment of Chronic Illness Therapy (FACIT) General Scale, including four well-being subscales. Shoulder pain intensity was measured using the Brief Pain Inventory, shoulder pain distress was measured using a 0-10 numerical rating scale, and functional impairment was measured using the FACIT Head and Neck Subscale. Shoulder function was assessed using a goniometer. Pearson correlations were initially applied to determine correlates (p <0.20) that should be entered in subsequent stepwise regression models. Findings and Implications: The only significant predictor of global HRQOL was eating impairment (B = -0.20, p = 0.02). Predictors of physical well-being were shoulder pain distress (B = -0.10, p = 0.02) and eating impairment (B = 0.27, p = 0.03). Predictors of functional well-being were speech impairment (B = -0.43, p < 0.01) and disfigurement (B = - 0.20, p = 0.02). No significant predictors were found for emotional and social well-being. The findings suggested that patients’ physical and functional well-being can be influenced by eating impairment, shoulder pain distress, speech impairment, or disfigurement at one month after HNC surgery. Nurses need to monitor nutrition intake, provide proper pain management, and collaborate with speech and physical therapists to promote early rehabilitation. A longitudinal study with a larger sample size is warranted to describe needs for multidisciplinary care to improve HQOL after HNC surgery

NuSTAR and Suzaku X-ray Spectroscopy of NGC 4151: Evidence for Reflection from the Inner Accretion Disk

We present X-ray timing and spectral analyses of simultaneous 150 ks Nuclear Spectroscopic Telescope Array (NuSTAR) and Suzaku X-ray observations of the Seyfert 1.5 galaxy NGC 4151. We disentangle the continuum emission, absorption, and reflection properties of the active galactic nucleus (AGN) by applying inner accretion disk reflection and absorption-dominated models. With a time-averaged spectral analysis, we find strong evidence for relativistic reflection from the inner accretion disk. We find that relativistic emission arises from a highly ionized inner accretion disk with a steep emissivity profile, which suggests an intense, compact illuminating source. We find a preliminary, near-maximal black hole spin a>0.9 accounting for statistical and systematic modeling errors. We find a relatively moderate reflection fraction with respect to predictions for the lamp post geometry, in which the illuminating corona is modeled as a point source. Through a time-resolved spectral analysis, we find that modest coronal and inner disk reflection flux variation drives the spectral variability during the observations. We discuss various physical scenarios for the inner disk reflection model, and we find that a compact corona is consistent with the observed features.Comment: 20 pages, 12 figures, accepted for publication in Ap

Biorthogonal quantum mechanics

The Hermiticity condition in quantum mechanics required for the characterization of (a) physical observables and (b) generators of unitary motions can be relaxed into a wider class of operators whose eigenvalues are real and whose eigenstates are complete. In this case, the orthogonality of eigenstates is replaced by the notion of biorthogonality that defines the relation between the Hilbert space of states and its dual space. The resulting quantum theory, which might appropriately be called 'biorthogonal quantum mechanics', is developed here in some detail in the case for which the Hilbert-space dimensionality is finite. Specifically, characterizations of probability assignment rules, observable properties, pure and mixed states, spin particles, measurements, combined systems and entanglements, perturbations, and dynamical aspects of the theory are developed. The paper concludes with a brief discussion on infinite-dimensional systems. © 2014 IOP Publishing Ltd