Investigating the Existence of Coherent Phonon Scattering in Silicon Using Phononic Crystals

In silicon the majority of heat energy is transported by phonons, which are discrete lattice vibrations. Phonon scattering due to the presence of voids in silicon can further alter the materials thermal conductivity. There is a question about the possibility of some of this scattering being coherent rather than purely incoherent. Coherent phonon scattering is defined as constructive interference of phonons scattered from the inclusions in the phononic crystal. The intent of this work is to investigate the existence of coherent scattering in Si via phononic crystals. A phononic crystal is a periodic array of inclusions inside a host material. The inclusions could be a second material or a void. In this work five different supercell phononic crystals comprised of holes in silicon will be used to investigate the existence of coherent phonon scattering. Each of the supercells had nearly identical critical lengths in order to keep the amount of incoherent scattering equal among all of the PnCs. Porosity differences among the supercells were also minimized. All of the PnCs were fabricated with a focused ion beam (FIB). During fabrication a protective layer of Ti was used to protect the Si from unintentional Ga doping from the FIB. The Ti layer also helped generate voids with more vertical sidewalls. A set of experiments was performed to measure the thermal conductivity of each PnC. Thermal conductivity measurements were carried out on a silicon nitride suspended island platform with platinum resistance temperature detectors and coated with aluminum nitride. A silicon slab was concurrently measured with each PnC, and relative thermal conductivity values were determined. The addition of the PnC decreased Si\u27s thermal conductivity to less than 22% of its original value. An analysis of the results shows there is a reduction in thermal conductivity beyond the effects of porosity and incoherent scattering. This enhanced reduction in thermal conductivity is due to coherent phonon scattering in PnCs.\u2

Estimating Product Characteristics and Spatial Competition in the Network Television Industry

Assessing the demand for products with characteristics that are unobservable or difficult to measure is becoming increasingly important with the growing proliferation and value of such products. Analyzing industry performance and firm competition in these sectors is hindered by the failure of traditional empirical methods to estimate demand for the products of these sectors. This paper focuses on the network television industry to present: (a) an empirical analysis of spatial competition, and (b) a structural approach to estimating product characteristics and consumer preferences in such industries, and (c) optimal network programming and scheduling given the estimated demand system. We use maximum simulated likelihood to estimate a structural model of viewer choice, yielding estimates of the latent characteristics of each show, the distribution of consumers' preferences for these characteristics, and the state dependence of choices. Results indicate the attribute space spans four dimensions of horizontal differentiation and one vertically differentiated dimension. Interpretations of these dimensions reflect the traditional show labels. For example, one of the dimensions represents the degree of realism in a show. Furthermore, the clustering of shows based on the estimated characteristics corresponds to traditional show labels. We identify four clusters --- sitcoms for mature viewers, sitcoms for younger viewers, reality based dramas, and fictional dramas. Regarding strategic behavior, our model suggests the networks should use counter-programming (i.e., differentiated products) within each time slot and homogeneous programming through each night. The estimated show locations reveal an extensive use of these strategies, as well as a limited degree of branding. Nonetheless, by unilaterally changing their schedules to increase both counter-programming and homogeneity, ABC, CBS, and NBC are able to increase their weekly ratings by 16%, 12%, and 15%, respectively. In a Nash equilibrium of the static scheduling game, these gains are reduced to 15%, 6%, and 12% increases.

The Relevance of Epigenetic Biomarkers for Breast Cancer and Obesity for Personalised Treatment in Public Healthcare: A Systematic Review

Background: Personalised medicine has gained attention as a result of the advances of genomic research in the last decade. This includes the rise in epigenetic research, which focuses on the environmental influences on the genome and examines biomarkers that might be useful for cancer therapy. This study investigates the epigenetic biomarkers for breast cancer and its risk factor, obesity, and evaluates their relevance for global public health. Methods: A systematic search of articles published from 2005 to May 2015 was performed in PubMed for epigenetic breast cancer marker. An additional literature search was carried out on the epigenetic markers of obesity. Results: The search resulted in 84 articles on breast cancer, which demonstrate the various applications of epigenetic markers for breast cancer diagnostics, prognostics and treatment. Particularly, non-invasive blood-based diagnostic biomarkers and epigenetic therapy could improve the health outcomes of cancer patients using a personalised approach. The 14 obesity-related articles highlight the epigenetic link of disease and risk factors and emphasise the relevance of nutritional influences. Conclusions: Although epigenetics offers many opportunities, new discoveries have to be confirmed first in clinical settings to ensure advantages over traditional methods. Furthermore, before personalised epigenetic therapy can be applied in public health it is crucial to ensure a fair implementation in both high and low-income settings globally

Brachial plexopathy after prone positioning

Two cases of brachial plexus injury after prone position in the intensive care unit are described. Mechanisms of brachial plexus injury are described, as are methods for prevention of this unusual complication

Automotive applications of thermoplastic vulcanizates

Thermoplastic vulcanizates (TPVs) are special classes of thermoplastic elastomers, in which dynamic vulcanization of the rubber phase takes place during melt mixing with a semicrystalline thermoplastic matrix phase at elevated temperature. This review article focus on the different types of thermoplastic vulcanizates (TPVs) from various elastomer and thermoplastic blends that are suitable for the automotive applications purpose. A detailed study of the various TPVs based on polypropylene-ethylene propylene diene rubber (PP-EPDM) and polypropylene-ethylene α-olefin has been focused and their application in the automobile sector has been summarized. Most of the commercially available TPVs are PP-EPDM based. Limited applications of that TPVs in high heat and oil resistant application purposes requires new generation of TPVs. High performance TPVs or super TPVs are new generation TPVs that exhibit high heat resistance as well as excellent oil resistance property suitable for automotive under-the-hood applications. Therefore TPVs based on XNBR-PA12, HNBR-PA12 and FKM-PA6 system has also been explored in details in this study and the possibility of the use of those TPV system has been focused for the high temperature application purpose in the automobile sector where high and oil resistant application properties is the prime concern

Information acquisition in a limit order market

Abstract We model an infinite horizon trading game of a limit order market with informed traders. Agents with a private and common value motive for trade randomly arrive in a market and may either post prices (submit limit orders) or accept posted prices (submit market orders). If their orders have not executed, traders may reenter the market and thus solve a dynamic problem. We consider agents' incentive to acquire information. We characterize how information acquisition changes agents' strategies and demonstrate the effect of this on the efficiency of market prices. We demonstrate that for some costs of acquiring information, there are multiple equilibria in the information acquisition game. Finally, we demonstrate that information acquisition can make all agents worse off

Interface-tuned epoxy/clay nanocomposites

Though interface has been known for a critical role in determining the properties of conventional composites, its role in polymer nanocomposites is still fragmented and in its infancy. This study synthesized a series of epoxy/clay nanocomposites with different interface strength by using three types of modifiers: ethanolamine (denoted ETH), Jeffamine� M2070 (M27) and Jeffamine� XTJ502 (XTJ). XTJ created a strong interface between clay layers and matrix because it bridged the layers with matrix by a chemical reaction as proved by Fourier transform infrared spectroscopy; M27 produced an interme-diate interface strength due to the molecular entanglement between grafted M27 chains and matrix molecules; the interface made by ETH was weak because neither chemical bridging nor molecular entanglement was involved. The studies of mechanical and thermal properties and morphology at a wide range of magnification show that the strong interface promoted the highest level of exfoliation and dispersion of clay layers, and achieved the most increment in Young’s modulus, fracture toughness and glass transition temperature (Tg) of matrix. With w1.3 wt% clay, the critical strain energy release rate G1c of neat epoxy improved from 179.0 to 384.7 J/m, 115% improvement and Tg enhanced from 93.7 to 99.