15,242 research outputs found
0-6711: Short Radius Mash TL-3 Guardrail Treatment
No full textSummary sheet describing research performed by the Texas A&M Transportation Institute regarding short radius Mash TL-3 guardrail treatment
Thermoluminescence of zircon: a kinetic model
No full textThe mineral zircon, ZrSiO4, belongs to a class of promising materials for geochronometry by means of thermoluminescence (TL) dating. The development of a reliable and reproducible method for TL dating with zircon requires detailed knowledge of the processes taking place during exposure to ionizing radiation, long-term storage, annealing at moderate temperatures and heating at a constant rate (TL measurements). To understand these processes one needs a kinetic model of TL. This paper is devoted to the construction of such amodel. The goal is to study the qualitative behaviour of the system and to determine the parameters and processes controlling TL phenomena of zircon. The model considers the following processes: (i) Filling of electron and hole traps at the excitation stage as a function of the dose rate and the dose for both (low dose rate) natural and (high dose rate) laboratory irradiation. (ii) Time dependence of TL fading in samples irradiated under laboratory conditions. (iii) Short time annealing at a given temperature. (iv) Heating of the irradiated sample to simulate TL experiments both after laboratory and natural irradiation.
The input parameters of the model, such as the types and concentrations of the TL centres and the energy distributions of the hole and electron traps, were obtained by analysing the experimental data on fading of the TL-emission spectra of samples from different geological locations. Electron paramagnetic resonance (EPR) data were used to establish the nature of the TL centres. Glow curves and 3D TL emission spectra are simulated and compared with the experimental data on time-dependent TL fading. The saturation and annealing behaviour of filled trap concentrations has been considered in the framework of the proposed kinetic model and comparedwith the EPR data associated with the rare-earth ions Tb3+ and Dy3+, which play a crucial role as hole traps and recombination centres. Inaddition, the behaviour of some of the SiOmn− centres has been compared with simulation results.
EXCHANGE RATE DETERMINATION OF TL/US$:A CO-INTEGRATION APPROACH
No full textIn our paper, we investigate exchange rate determination mechanism of TL/US$ for the 1987Q1-2006Q4 period using quarterly observations. Following a large literature review we first highlight various approaches explaining monetary model exchange rate determination based on economic fundamentals and then construct an empirical model revealing both long-run stationary relationships and short-run dynamic adjustment processes of the nominal exchange rate for the Turkish economy. Our findings employing multivariate Johansen-Juselius type co-integrating approach indicate that nominal exchange rate is co-integrated with the fundamentals suggested by economics theory. Besides, short-run deviations from the fundamental-based equilibrium course of the nominal exchange rate have permanent effects on the long-run equilibrium exchange rate and so have been stemmed from the existence of some form of hysteresis effects dominated in the nominal exchange rate.Exchange Rates; Sticky Price Monetary Model; Flexible Price Monetary; Economic Fundamentals; Randow Walk; Co-integration; Hysteresis; Turkish Economy
Short time scales in the Kramers problem: A stepwise growth of the escape flux
No full textWe prove rigorously and demonstrate in simulations that. for a potential system staying initially at the bottom of a well, the escape flux over the barrier grows on times of the order of a period of eigenoscillation in a stepwise manner, provided that friction is: small or moderate. If the initial state is not at the bottom of the well, then, typically, some of the steps transform into oscillations. The stepwise/oscillatory evolution at short times appears to be a generic feature of a noise-induced flux
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Coherent-precipitate formation in Tl-implanted Si
No full textIon scattering, ion channeling, and cross-section electron microscopy were used to investigate Si single crystals implanted with /sup 205/Tl/sup +/ (0.29 - 1 x 10/sup 16/ Tl/cm/sup 2/, 90 keV) and annealed with pulses (1.6 J/cm/sup 2/, 15 ns) from a ruby laser. Coherent precipitates of Tl were found to form as a result of laser processing. The systematics of the effect are presented and a formation mechanism proposed
Making postdramatic theatre : a handbook of devising exercises
No full textMaking Postdramatic Theatre is a workshop handbook for tutors teaching postdramatic practice and for students and makers devising their own performance work. It extends the range of workshop manuals on devised theatre that are currently on the market by, uniquely, focusing specifically around exercises that can be used for making theatre that is postdramatic. It is compiled of workshop exercises contributed by a range of established UK and trans-European theatre companies and practitioners who tour their work internationally. The book includes: an accessible introduction to Postdramatic Theatre, written by Tracy Crossley; 17 edited exercises or full workshops contributed by 11 theatre practitioners; exercises grouped into chapters on Action, Text, Space and Time, framed with short introductions; boxed interventions from the editors on each exercise, with suggestions for further development and/or cross references to other complimentary exercises in the handbook; practitioner profiles and external hyperlinks to websites and video documentation; hyperlinks that direct the user to other relevant materials on Digital Theatre Plus; annotated Further Reading and Resources section
Dynamic Voltage Support by TL-PV Systems to Mitigate Short-Term Voltage Instability in Residential DN
No full textRecently, transformerless (TL) inverters are being extensively used in small-scale photovoltaic (PV) systems due to their compact-size, lighter-weight, lower-cost and higher-efficiency compared to their counterpart with transformer. However, the growing penetration of these small-scale based PV systems and low-inertia induction motor (IM) loads in low-voltage distribution networks (DNs) make the grid more vulnerable to short-term voltage stability (STVS). Hence, this paper thoroughly examines the STVS of DN with high-penetration of TL-PV units, and provides countermeasures by TL-PV systems to mitigate any short-term voltage instability. The detailed dynamic model of the TL inverter is developed first. Next, three control strategies: (1) constant peak current (CPC), (2) constant active current (CAC), and (3) constant active power (CAP) with low voltage ride through (LVRT) and dynamic voltage support (DVS) capabilities are proposed to improve STVS. The impacts of different level of PV penetrations and LVRT capability of TL-PV inverters on the STVS are explored. Moreover, countermeasures, such as LVRT with CAC and CAP controls and DVS by the TL-PV systems are designed and implemented. Several case studies are carried out on an IEEE 4 bus system first, and later extended to IEEE 13 node test feeder. The results show that DVS can further improve STVS in residential DNs. In addition, CAP and CAC control strategies can speed-up the postdisturbance voltage recovery compared with the conventional CPC control
Dynamic Voltage Support by TL-PV Systems to Mitigate Short-Term Voltage Instability in Residential DN
No full textRecently, transformerless (TL) inverters are being extensively used in small-scale photovoltaic (PV) systems due to their compact-size, lighter-weight, lower-cost and higher-efficiency compared to their counterpart with transformer. However, the growing penetration of these small-scale based PV systems and low-inertia induction motor (IM) loads in low-voltage distribution networks (DNs) make the grid more vulnerable to short-term voltage stability (STVS). Hence, this paper thoroughly examines the STVS of DN with high-penetration of TL-PV units, and provides countermeasures by TL-PV systems to mitigate any short-term voltage instability. The detailed dynamic model of the TL inverter is developed first. Next, three control strategies: (1) constant peak current (CPC), (2) constant active current (CAC), and (3) constant active power (CAP) with low voltage ride through (LVRT) and dynamic voltage support (DVS) capabilities are proposed to improve STVS. The impacts of different level of PV penetrations and LVRT capability of TL-PV inverters on the STVS are explored. Moreover, countermeasures, such as LVRT with CAC and CAP controls and DVS by the TL-PV systems are designed and implemented. Several case studies are carried out on an IEEE 4 bus system first, and later extended to IEEE 13 node test feeder. The results show that DVS can further improve STVS in residential DNs. In addition, CAP and CAC control strategies can speed-up the postdisturbance voltage recovery compared with the conventional CPC control.Full Tex
Tangle-bearing neurons survive despite disruption of membrane integrity in a mouse model of tauopathy
No full textNeurofibrillary tangles (NFTs) are associated with neuronal loss and correlate with cognitive impairment in Alzheimer disease, but how NFTs relate to neuronal death is not clear. We studied cell death in Tg4510 mice that reversibly express P301L mutant human tau and accumulate NFTs using in vivo multiphoton imaging of neurofibrillary pathology, propidium iodide (PI) incorporation into cells, caspase activation, and DNA labeling. We first observed that in live mice, a minority of neurons were labeled with the caspase probe or with PI fluorescence. These markers of cell stress were localized in the same cells and appeared specifically within NFT-bearing neurons. Contrary to expectations, the PI-stained neurons did not die during a day of observation; the presence of Hoechst-positive nuclei in them on the subsequent day indicated that the NFT-associated membrane disruption, as suggested by PI staining, and caspase activation do not lead to immediate death of neurons in this tauopathy model. This unique combination of in vivo multiphoton imaging with markers of cell death and pathological alteration is a powerful tool for investigating neuronal damage associated with neurofibrillary pathology
Theoretical study in [C2H4-Tl](+) and [C2H2-Tl](+) complexes
No full textWe studied the attraction between [C2Hn] and Tl(I) in the hypothetical [C2Hn-Tl](+) complexes (n = 2,4) using ab initio methodology. We found that the changes around the equilibrium distance C-Tl and in the interaction energies are sensitive to the electron correlation potential. We evaluated these effects using several levels of theory, including Hartree-Fock (HF), second-order Moller-Plesset (MP2), MP4, coupled cluster singles and doubles CCSD(T), and local density approximation augmented by nonlocal corrections for exchange and correlation due to Becke and Perdew (LDA/BP). The obtained interaction energies differences at the equilibrium distance R-e (C-Tl) range from 33 and 46 kJ/mol at the different levels used. These results indicate that the interaction between olefinic systems and Tl(l) are a real minimum on the potential energy surfaces (PES). We can predict that these new complexes are viable for synthesizing. At long distances, the behavior of the [C2Hn]-Tl+ interaction may be related mainly to charge-induced dipole and dispersion terms, both involving the individual properties of the olefinic pi-system and thallium ion. However, the charge-induced dipole term (R-4) is found as the principal contribution in the stability at long and short distances
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