Azimuthal anisotropy (v2v_{2}) of high-pT_{T} π0\pi^{0} and direct γ\gamma in Au+Au collisions at sNN\sqrt{s_{NN}} = 200 GeV

Preliminary results from the STAR collaboration of the azimuthal anisotropy $(v_{2})$ of $\pi^{0}$ and direct photon ($\gamma_{dir}$) at high transverse momentum (p$_{T}$) from Au+Au collisions at center-of-mass energy $\sqrt{s_{_{NN}}}=200$~GeV are presented. A shower-shape analysis is used to select a sample free of direct photons ($\pi^0$) and a sample rich in direct photons $\gamma_{rich}$. The relative contribution of background in the $\gamma_{rich}$ sample is determined assuming no associated charged particles nearby $\gamma_{dir}$. The $v_{2}$ of direct photons ($v_{2}^{\gamma_{dir}}$) at mid-rapidity ($|\eta^{\gamma_{dir}}|<1$) and high p$_{T}$ ($8< p_{T}^{\gamma_{dir}}<16$~GeV/$c$) is extracted from those of $\pi^{0}$ and neutral particles measured in the same kinematic range. In mid-central Au+Au collisions (10-40$\%$), the $v_{2}$ of $\pi^0$ ($v_{2}^{\pi^{0}}(p_{T})$) and charged particles ($v_{2}^{ch}(p_{T})$) are found to be $\sim$ 0.12 and nearly independent of p$_{T}$. The measured $v_{2}^{\gamma_{dir}}(p_{T})$ is positive finite and systematically smaller than that of $\pi^{0}$ and charged particles by a factor of $\sim$ 3. Although the large $v_{2}^{\pi^{0}}$ at such high p$_{T}$ might be partially due to the path-length dependence of energy loss, the non-zero value of $v_{2}^{\gamma_{dir}}$ indicates a bias of the reaction plane determination due to the presence of jets in the events. Systematic studies are currently in progress.Comment: 4 pages, 2 figures, Hot Quarks 2010, LaLonde Franc

NanoThermoMechanical Logic Gates for Thermal Computing

Limited performance and reliability of electronic devices at extreme temperatures, intensive electromagnetic fields, and radiation found in space exploration missions (i.e., Venus & Jupiter planetary exploration, and heliophysics missions) and earth-based applications require the development of alternative computing technologies. Thermal computing, data processing based on heat instead of electricity, is proposed as a practical alternative and opens a new scientific area at the interface between thermal and computational sciences. We successfully developed thermal AND, OR and NOT logic gates, achieved through the coupling between near-field thermal radiation and MEMS thermal actuation. In the process, we developed two novel non-linear thermal expansion designs of microstructure silicon V-shaped chevron beams which were required to achieve the desired thermal AND gate operation. The successful design paves the way to develop full thermal logic circuits, so we show the design and simulation of a thermal calculator based on binary mathematical computations. This thermal calculator was able to perform the addition of two decimal numbers. Furthermore, we introduce the microfabrication and characterization of the thermal AND and OR logic gates. The thermal AND logic gate consists of two non-linear mechanisms using novel and ingenious chevron mechanisms consisting of spring-assisted reduction and cascading chevrons amplification for the reducing and the amplification mechanisms, respectively. The experimental results show that we achieved non-linearity ratios of thermal expansion of 0.36 and 3.06 for the reducing and the amplification mechanisms, respectively. For the characterization of thermal AND logic gate, for the case when the two inputs were at (i.e., 0,0 case), we achieved an effectiveness of 10.7 % at a heat source temperature of 1549 K. For the thermal OR logic gate, for the cases of (1,0) and (0,1), we achieved an effectiveness of 25.3 % and 23.2 % at an input temperature of 1324 K and 1391 K, respectively. These results are significant breakthroughs in the field of thermal computation science and technology as they demonstrate thermal computing at high temperatures based on demonstrated and easy to manufacture NanoThermoMechanical logic gates. Advisor: Sidy Nda

NanoThermoMechanical Logic Gates for Thermal Computing

Limited performance and reliability of electronic devices at extreme temperatures, intensive electromagnetic fields, and radiation found in space exploration missions (i.e., Venus & Jupiter planetary exploration, and heliophysics missions) and earth-based applications require the development of alternative computing technologies. Thermal computing, data processing based on heat instead of electricity, is proposed as a practical alternative and opens a new scientific area at the interface between thermal and computational sciences. We successfully developed thermal AND, OR and NOT logic gates, achieved through the coupling between near-field thermal radiation and MEMS thermal actuation. In the process, we developed two novel non-linear thermal expansion designs of microstructure silicon V-shaped chevron beams which were required to achieve the desired thermal AND gate operation. The successful design paves the way to develop full thermal logic circuits, so we show the design and simulation of a thermal calculator based on binary mathematical computations. This thermal calculator was able to perform the addition of two decimal numbers. Furthermore, we introduce the microfabrication and characterization of the thermal AND and OR logic gates. The thermal AND logic gate consists of two non-linear mechanisms using novel and ingenious chevron mechanisms consisting of spring-assisted reduction and cascading chevrons amplification for the reducing and the amplification mechanisms, respectively. The experimental results show that we achieved non-linearity ratios of thermal expansion of 0.36 and 3.06 for the reducing and the amplification mechanisms, respectively. For the characterization of thermal AND logic gate, for the case when the two inputs were at (i.e., 0,0 case), we achieved an effectiveness of 10.7 % at a heat source temperature of 1549 K. For the thermal OR logic gate, for the cases of (1,0) and (0,1), we achieved an effectiveness of 25.3 % and 23.2 % at an input temperature of 1324 K and 1391 K, respectively. These results are significant breakthroughs in the field of thermal computation science and technology as they demonstrate thermal computing at high temperatures based on demonstrated and easy to manufacture NanoThermoMechanical logic gates. Advisor: Sidy Nda

Economic Valuation Of Florida Sea Turtles In Face Of Sea Level Rise

Sea level rise (SLR) is posing a great risk of flooding and inundation to coastal areas in Florida. Some coastal nesting species, including sea turtle species, have experienced diminished habitat from SLR. In an effort to assess the economic and ecosystem service loss to coastal areas with respect to sea turtles Contingent Valuation Method (CVM) and Habitat Equivalency Analysis (HEA) were used. The CVM was used to measure the economic impacts of SLR on sea turtles. Open-ended and dichotomous choice CVM was used to obtain the willingness to pay (WTP) values of Florida residents to implement certain mitigation strategies which would protect Florida’s east coast sea turtle nesting areas. The problem of sample selection bias was reduced by surveying residents of two cities that would potentially have varying interest in coastal conservation due to their relative distance from the coast. The hypothetical WTP of Florida households to implement policies designed to protect sea turtle habitat from development encroachment was estimated to be between $21 and$29 per year for a maximum of five years. Characteristics of respondents were found to have statistically significant impacts on their WTP. Findings include a negative correlation between the age of a respondent and the probability of an individual willing to pay the hypothetical WTP amount. Counter intuitively, it was found that WTP of an individual was not dependent on prior knowledge of the effects of SLR on sea turtle habitat. As the level of this awareness increased, the probability to pay the hypothetical WTP value decreased. The greatest indicators of whether or not an individual was willing to pay to protect sea turtle habitat were the respondents’ perception regarding the importance of sea turtle population health to the ecosystem, and their confidence in the conservation methods used. iii Concepts of Habitat Equivalency Analysis were used in order to determine the ecosystem service lost due to SLR. The study area of Archie Carr National Wildlife Refuge (ACNWR) has a continually increasing sea turtle population due to various conservation efforts. However, how the inundation of the coastal area will injure this habitat was assessed, and if mitigation strategies to compensate for the loss are necessary. The carrying capacity (CC) of the refuge was chosen as the metric of the ecosystem service. Using the estimated area of ACNWR and the approximate area needed by a sea turtle to nest, the theoretical number of sea turtle nests possible on the refuge was calculated. This value was then projected to the year 2100 using the sea level rise scenarios provided by IPCC (2007) and NRC (2010). In order to quantify the injury caused by the decrease in the refuge’s CC, the number of sea turtle nests on the refuge was projected to the year 2100 using the data obtained over the past 30 years. The analysis concludes a potential loss of service to be experienced as early as 2060’s due to the carrying capacity of the refuge diminishing with the loss of the habitat due to the increase in the mean sea level

Non-Linear Analysis Of Reinforced And Pre-Stressed Concrete Beams

Reinforced/pre-stressed (RC/PC) concrete is one of the most commonly used construction materials. This composite material demonstrates a highly non-linear behaviour caused by, cracking, crushing, aggregate interlock, bond slip, dowel action, shrinkage, creep, etc. Because the behaviour of reinforced/pre-stressed concrete involves so many non-linear phenomena interacting with one other, the formulation of rational analytical procedures to describe this behaviour is very difficult Since the advent of the computer, powerful methods of analysis such as the finite element method and stiffness matrix method have been implemented to study and develop analytical solutions for the non-linear phenomena. However, the success of such analysis depends on a thorough understanding and modeling of the composite material behaviour.This study describes the development of a non-linear computer code used to predict the non-liner response of reinforced/pre-stressed concrete beams that are subjected to a combined axial force and bending moment The study discusses a new simplified approach, whereby the non-linear response is captured via a series of sequentially linear steps. The finite element approach with the stiffness matrix method were used to model the beam element structure and generate its stiffness matrix. A monotonic empirical model for the concrete's stress-strain curve has been implemented to predict both ascending and descending parts of the curve. An idealized bi-linear elasto-plastic in tension and compression model has been assumed for reinforcing and pre-stressing steel