Effectiveness of median cable barrier in Iowa

Median-crossover crashes involve a vehicle departing the travel lane, traversing the median, and striking either a fixed object or an oncoming vehicle in the opposing direction of traffic. These types of crashes present the highest risk of fatal and severe injuries among all collision types on freeways. Median-crossover crashes are caused by a variety of factors, including driver distraction, impaired driving, mechanical failure, and loss of control. Median barriers are the primary countermeasure to reduce the opportunity for multi-vehicle cross-median crashes. Due to the lower installation costs, as compared to more rigid systems, high-tension median cable barrier has become a popular countermeasure for reducing such crashes. The Iowa Department of Transportation (Iowa DOT) began installing high-tension median cable barriers in 2003 and will have approximately 330 miles of such barrier installed on freeways statewide by the end of 2018. While anecdotal evidence suggests that cable barriers are functioning as desired, no in-depth analysis of performance or cost-effectiveness has been conducted to date. This project aims to determine the cost-effectiveness of median cable barrier systems based on crash cost savings resulting from reductions in fatal and injury crashes as compared to the costs associated with increased property-damage-only crashes, installation costs, and ongoing maintenance costs. An in-depth analysis of the frequency and severity of crashes occurring in the freeway median was conducted. This research identified general trends in crash frequency and severity between the pre- and post-installation periods. Following an extensive manual review of crash narratives, a before-and-after study design showed the overall impact of the median cable barrier program was a 51.3% reduction in fatal crashes. The barrier program also showed an 80.4% increase in total crashes, which was driven by an increase in property-damage-only crashes of 118.1%. Installation and maintenance repair costs on the barrier were investigated and discussed. The design life of the median cable barrier was recommended to be 20 years with a benefit-cost ratio of 9.153. Geometric characteristics such as median width, shoulder width, and barrier offset were investigated, but no significant trends were identified. Future research as to the relationship between roadway geometric characteristics and median cable barrier effectiveness is recommended in order to plan for subsequent installations of median cable barrier in Iowa

Challenges in the land of hope: Phoenix area refugees and the recession

Refugees in the United States today have greater access than ever to training programs and specialized service providers who assist with cultural adjustment to the U.S. as well as pre-employment training, job placement and retention services. Service providers develop job opportunities in the local community through partnerships with dedicated employers who see value in hiring new Americans and purpose in collaborating with voluntary agencies to overcome barriers for employees. During the recession there has been greater challenges for employment specialists to find employment for refugee clients and employers have noted some reluctance in hiring employees with low or non-existent English language skills. Once hired, refugees present other types of challenges for supervisors tasked with training these employees with language and cultural barriers. Lutheran Social Services Refugee and Immigration Services (LSS-SW) program in Phoenix, Arizona is a voluntary refugee resettlement agency providing employment services and training programs to assist with job placement and retention. This inquiry sought to determine ways LSS-SW staff might collaborate with potential employers to increase the number of refugee clients hired while maintaining job retention for hires. The inquiry also sought to better understand the experiences of employers to determine improved training for employees, as well as what industries are hiring locally during the recession. Employers were asked to assess their own needs for training, whether or not there was a presence of discrimination for refugees in their companies and about the misconceptions of supervisors and non-refugee co-workers. Eleven employers who currently employ refugee clients from the agency as well as three employment specialists were interviewed as a part of this inquiry

Alien Registration- Nightingale, Frank E. (Houlton, Aroostook County)

https://digitalmaine.com/alien_docs/34745/thumbnail.jp

Monte Carlo computation of correlation times of independent relaxation modes at criticality

We investigate aspects of universality of Glauber critical dynamics in two dimensions. We compute the critical exponent $z$ and numerically corroborate its universality for three different models in the static Ising universality class and for five independent relaxation modes. We also present evidence for universality of amplitude ratios, which shows that, as far as dynamic behavior is concerned, each model in a given universality class is characterized by a single non-universal metric factor which determines the overall time scale. This paper also discusses in detail the variational and projection methods that are used to compute relaxation times with high accuracy

Transfer-Matrix Monte Carlo Estimates of Critical Points in the Simple Cubic Ising, Planar and Heisenberg Models

The principle and the efficiency of the Monte Carlo transfer-matrix algorithm are discussed. Enhancements of this algorithm are illustrated by applications to several phase transitions in lattice spin models. We demonstrate how the statistical noise can be reduced considerably by a similarity transformation of the transfer matrix using a variational estimate of its leading eigenvector, in analogy with a common practice in various quantum Monte Carlo techniques. Here we take the two-dimensional coupled $XY$-Ising model as an example. Furthermore, we calculate interface free energies of finite three-dimensional O($n$) models, for the three cases $n=1$, 2 and 3. Application of finite-size scaling to the numerical results yields estimates of the critical points of these three models. The statistical precision of the estimates is satisfactory for the modest amount of computer time spent

Finite size scaling of the correlation length above the upper critical dimension

We show numerically that correlation length at the critical point in the five-dimensional Ising model varies with system size L as L^{5/4}, rather than proportional to L as in standard finite size scaling (FSS) theory. Our results confirm a hypothesis that FSS expressions in dimension d greater than the upper critical dimension of 4 should have L replaced by L^{d/4} for cubic samples with periodic boundary conditions. We also investigate numerically the logarithmic corrections to FSS in d = 4.Comment: 5 pages, 6 postscript figure

Decoupling in the 1D frustrated quantum XY model and Josephson junction ladders: Ising critical behavior

A generalization of the one-dimensional frustrated quantum XY model is considered in which the inter and intra-chain coupling constants of the two infinite XY (planar rotor) chains have different strengths. The model can describe the superconductor to insulator transition due to charging effects in a ladder of Josephson junctions in a magnetic field with half a flux quantum per plaquette. From a fluctuation-effective action, this transition is expected to be in the universality class of the two-dimensional classical XY-Ising model. The critical behavior is studied using a Monte Carlo transfer matrix applied to the path-integral representation of the model and a finite-size-scaling analysis of data on small system sizes. It is found that, unlike the previous studied case of equal inter and intra-chain coupling constants, the XY and Ising-like excitations of the quantum model decouple for large interchain coupling, giving rise to pure Ising model critical behavior for the chirality order parameter and a superconductor-insulator transition in the universality class of the 2D classical XY model.Comment: 15 pages with figures, RevTex 3.0, INPE-93/00

Conformal Anomaly and Critical Exponents of the XY-Ising Model

We use extensive Monte Carlo transfer matrix calculations on infinite strips of widths $L$ up to 30 lattice spacing and a finite-size scaling analysis to obtain critical exponents and conformal anomaly number $c$ for the two-dimensional $XY$-Ising model. This model is expected to describe the critical behavior of a class of systems with simultaneous $U(1)$ and $Z_2$ symmetries of which the fully frustrated $XY$ model is a special case. The effective values obtained for $c$ show a significant decrease with $L$ at different points along the line where the transition to the ordered phase takes place in a single transition. Extrapolations based on power-law corrections give values consistent with $c=3/2$ although larger values can not be ruled out. Critical exponents are obtained more accurately and are consistent with previous Monte Carlo simulations suggesting new critical behavior and with recent calculations for the frustrated $XY$ model.Comment: 33 pages, 13 latex figures, uses RevTeX 3.

Quantum Pairing of Impurities in Quantum Crystals

We calculated the time of pairing by quantum diffusion of ortho-H2 impurities in solid para-H2. The important feature of the pairing process is a strong directional bias associated with the dependence of the hopping rates on energy mismatches caused by the interaction of the pairing particles. This bias at moderate temperatures is against a mutual approach of particles and creates a ‘‘kinetic barrier.’’ At lower temperatures, the corresponding diffusion mechanism freezes out, which leads to a rapid increase in pairing rates. This explains a well-developed, experimentally observed maximum in the pairing time as a function of temperature: a maximum that exists in spite of a monotonic temperature dependence of individual hopping rates. Our results are in good agreement with experimental data