Perfect Reflection of Chiral Fermions in Gated Graphene Nanoribbons

We describe the results of a theoretical study of transport through gated metallic graphene nanoribbons using a non-equilibrium Green function method. Although analogies with quantum field theory predict perfect transmission of chiral fermions through gated regions in one dimension, we find \emph{perfect reflection} of chiral fermions in armchair ribbons for specific configurations of the gate. This effect should be measurable in narrow graphene constrictions gated by a charged carbon nanotube.Comment: 9 pages, 3 figures. Submitted to Nano Letter

Spectra of produced particles at CERN SPS heavy-ion collisions from a parton-cascade model

We evaluate the spectra of produced particles (pions, kaons, antiprotons) from partonic cascades which may develop in the wake of heavy-ion collisions at CERN SPS energies and which may hadronize by formation of clusters which decay into hadrons. Using the experimental data obtained by NA35 and NA44 collaborations for S+S and Pb+Pb collisions, we conclude that the Monte Carlo implementation of the recently developed parton-cascade/cluster-hadronization model provides a reasonable description of the distributions of the particles produced in such collisions. While the rapidity distribution of the mid-rapidity protons is described reasonably well, their transverse momentum distribution falls too rapidly compared to the experimental values, implying a significant effect of final state scattering among the produced hadrons neglected so far

Pengelolaan Sarana Dan Prasarana Praktik Pada Jurusan Tata Busana

The puspose of this research is to describe the management of infrastructure practice in the dressmaking departement at SMK Negeri 3 Bengkulu City” Consists of planning, procurement, inventory, storage, use, maintance and removal. This study used descriptive qualitative approach, and the respondents were the principle, vice principle of infrastructure affarirs, staf facilities and infrastructure, and productive teachers of dressmaking departement. The techniques of data collection used interview, observation and documentation. The result show the management of the practicing facilities of dressmaking departement of secondary at SMK Negeri 3 Bengkulu City was conducated in accordance with applicable regulatons, but there are some aspect of management that are not implemented

Detecting Malicious Code by Model Checking

Abstract. The ease of compiling malicious code from source code in higher programming languages has increased the volatility of malicious programs: The first appearance of a new worm in the wild is usually followed by modified versions in quick succession. As demonstrated by Christodorescu and Jha, however, classical detection software relies on static patterns, and is easily outsmarted. In this paper, we present a flexible method to detect malicious code patterns in executables by model checking. While model checking was originally developed to verify the correctness of systems against specifications, we argue that it lends itself equally well to the specification of malicious code patterns. To this end, we introduce the specification language CTPL (Computation Tree Predicate Logic) which extends the well-known logic CTL, and describe an efficient model checking algorithm. Our practical experiments demonstrate that we are able to detect a large number of worm variants with a single specification. Key words: Model Checking, Malware Detection.

Use of a Simulation Model to Evaluate the Influence of Reproductive Performance and Management Decisions on Net Income in Beef Production

A stochastic dynamic model of reproduction and a deterministic cow-herd economic simulation model were used to evaluate how management decisions and reproductive performance interact to influence net income in a cow-calf operation (1,000 cows) for 1 yr of production. The stochastic model was used to determine herd performance when length of breeding season (45, 70, or 120 d) interacted with three postpartum intervals of an estrus (48, 65, or 90 d) and three conception rates at first service (60, 70, or 80%). Short, moderate, and long postpartum intervals were used to reflect differences in reproductive performance. In addition, replacement heifers were bred beginning either 3 wk ahead of the cow herd or at the same time as the cow herd. Fifty-four simulations were generated. Inputs into the economic model were herd performance, livestock and feed prices, nonfeed costs, and feed requirements for 1 yr of production. Feed requirements were calculated separately for each postpartum interval to reflect three different body condition scores, thin, moderate, and good, to correspond with long, moderate, and short postpartum intervals. Net income was greatest with 704 breeding seasons when the postpartum interval was short or moderate. When the postpartum interval was long, net income was greatest with 1204 breeding seasons because pregnancy rates, as a result of the long breeding season, were highest and feed costs were lowest for thin cows. Overall, net income was greatest when cows were managed to have postpartum intervals of moderate length. Breeding heifers 3 wk before the cows provided the most economic benefit with long postpartum intervals

Applying proximity sensors to monitor beef cattle social behaviour as an indicator of animal welfare

There are currently no approved monitoring programs in the beef industry that use paddock based behaviour as an indicator of animal welfare. Current animal welfare assessments are conducted at a single point in time, such as supplying food and water and treating illnesses as these needs arise. These aspects comply with the five freedoms that animals should have when addressing animal welfare, however, the assessments are infrequent. Of the five freedoms, the freedom to express normal behaviour can be a subjective measure, due to differences in the way individual animals express certain behaviours. There is a need for continual monitoring of welfare indicators in modern animal assessment methods to objectively measure behaviour and address public concerns about the welfare state of animals. The experiment commenced in June 2017 to assess changes in cattle social interaction patterns in response to social stress created by regrouping four groups of eight heifers. Previous research with cattle has provided evidence that social contact and spatial behaviour differ when novel individuals are introduced (Patison et al., 2010b), and re-grouped animals continue to experience stress until the social hierarchy is re-established after regrouping (Kondo and Hurnik, 1990). Proximity sensors that record the frequency and duration of close proximity contacts (<4 m) will be used to remotely collect animal association data, while blood cortisol concentrations will be used as an independent measure of stress. Responses to stress will be compared with a group of heifers where re-grouping does not occur. This paper outlines the background and methodology to explore the potential for proximity sensors as a continual welfare monitoring device, related to an animal’s freedom to express normal behaviour. Preliminary results of the project will be presented at The International Tri-Conference for Precision Agriculture held in New Zealand in October, 2017

Overview of Boundary Layer Transition Research in Support of Orbiter Return To Flight

A predictive tool for estimating the onset of boundary layer transition resulting from damage to and/or repair of the thermal protection system was developed in support of Shuttle Return to Flight. The boundary layer transition tool is part of a suite of tools that analyze the aerothermodynamic environment to the local thermal protection system to allow informed disposition of damage for making recommendations to fly as is or to repair. Using mission specific trajectory information and details of each damage site or repair, the expected time (and thus Mach number) at transition onset is predicted to help define the aerothermodynamic environment to use in the subsequent thermal and stress analysis of the local thermal protection system and structure. The boundary layer transition criteria utilized for the tool was developed from ground-based measurements to account for the effect of both protuberances and cavities and has been calibrated against select flight data. Computed local boundary layer edge conditions were used to correlate the results, specifically the momentum thickness Reynolds number over the edge Mach number and the boundary layer thickness. For the initial Return to Flight mission, STS-114, empirical curve coefficients of 27, 100, and 900 were selected to predict transition onset for protuberances based on height, and cavities based on depth and length, respectively

Environmental Effects on Neonatal Mortality of Beef Calves

Calving records from 1969 to 1989 from the Roman L. Hruska U.S. Meat Animal Research Center were used to investigate how climatic conditions, in addition to dystocia, age of dam, size of calf, and sex affect calf survival from birth to 1 wk of age. Data were analyzed separately for cows calving with (n = 11,094) or without (n = 72,187) dystocia. Neonatal mortality was described by a logit model and parameters were estimated by maximum-likelihood procedures. Calves born to cows with dystocia were five times as likely to die neonatally than calves born without assistance. Of all calves that died, 43.6% were born with difficulty. Of these calves, survival was lowest for those that were small relative to their genetic group, sex, and age of dam. Large calves had markedly increased mortality only when born to 2-yr-old dams. Average ambient temperature and precipitation on day of calving affected survival nonlinearly and the magnitude of the effect depended on age of dam, sex and size of calf, and dystocia incidence. Calves born to 2-yr-old cows were more susceptible to severe weather conditions than calves born to older cows. The negative effect of precipitation on survival increased with decreasing temperature

Ground-state properties of the spin-1/2 antiferromagnetic Heisenberg model on the triangular lattice: A variational study based on entangled-plaquette states

We study, on the basis of the general entangled-plaquette variational ansatz, the ground-state properties of the spin-1/2 antiferromagnetic Heisenberg model on the triangular lattice. Our numerical estimates are in good agreement with available exact results and comparable, for large system sizes, to those computed via the best alternative numerical approaches, or by means of variational schemes based on specific (i.e., incorporating problem dependent terms) trial wave functions. The extrapolation to the thermodynamic limit of our results for lattices comprising up to N=324 spins yields an upper bound of the ground-state energy per site (in units of the exchange coupling) of $-0.5458(2)$ [$-0.4074(1)$ for the XX model], while the estimated infinite-lattice order parameter is $0.3178(5)$ (i.e., approximately 64% of the classical value).Comment: 8 pages, 3 tables, 2 figure