First-passage method for the study of the efficiency of a two-channel reaction on a lattice

We study the efficiency of a two-channel reaction between two walkers on a finite one-dimensional periodic lattice. The walkers perform a combination of synchronous and asynchronous jumps on the lattice and react instantaneously when they meet at the same site (first channel) or upon position exchange (second channel). We develop a method based on a conditional first-passage problem to obtain exact results for the mean number of time steps needed for the reaction to take place as well as for higher order moments. Previous results obtained in the framework of a difference equation approach are fully confirmed, including the existence of a parity effect. For even lattices the maximum efficiency corresponds to a mixture of synchronous events and a small amount of asynchronous events, while for odd lattices the reaction time is minimized by a purely synchronous process. We provide an intuitive explanation for this behavior. In addition, we give explicit expressions for the variance of the reaction time. The latter displays a similar even-odd behavior, suggesting that the parity effect extends to higher order moments.Comment: 17 pages, 2 tables, 6 figures, revtex

Stress and psychological wellbeing in local humanitarian workers in Colombia working for a local non-governmental organization : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Arts in Psychology at Massey University, Albany, New Zealand

This study examined the differences in stress and psychological wellbeing in 75 local humanitarian personnel (70 females and 5 males, median age = 30.7) from "Fundacion CC", local non-governmental organisation from Medellin, Colombia, who worked either in the field, with the communities they help, or in an administrative facility, doing managerial and planning types of work. Participants answered the Stress Profile questionnaire in order to assess the impact of background variables such as place of work and age, and variables theoretically associated to the processes of stress such as social support, cognitive hardiness and coping styles, on their current levels of stress and psychological wellbeing. Despite increasing worldwide evidence showing the significant impacts of humanitarian work in the field on stress and mental health of humanitarian staff, all participants consistently showed low levels of stress and high levels of psychological wellbeing regardless of place of work and any other differences among them. Additionally, this study showed that variables theorized in the literature as relevant to stress were instead more significant to assess psychological wellbeing in the sample of participants. Results and implications were discussed within the guidelines of transactional models of stress

Thermodynamic properties of the XX model in a chain with a period two and three coupling

The exact solutions for the energy spectrum of the XX model with a periodic coupling and an external transverse magnetic field $h$ are obtained. The diagonalization procedure is discussed, and analytical and numerical solutions are given. Using the solutions for period-two coupling, the free energy, entropy, and specific heat are calculated as functions of temperature and applied transverse external magnetic field. Their expressions show that below a particular value $v$ and above a value $u$ of the magnetic field $|h|$, the entropy and the specific heat vanish exponentially in the low temperature limit.Comment: 20 pages, 9 figures, new references adde

Canonical equivalence relations on nets of PSc0PS_{c_0}

We give a list of canonical equivalence relations on discrete nets of the positive unit sphere of $c_0$. This generalizes results of W. T. Gowers and A. D. Taylor.Comment: 41 page

Decomposition of Pig Carcasses at Varying Room Temperature

The goal of this study is to assess the qualitative scoring of decomposition scales with statistical analysis while also determining which indoor environment will decompose the fastest. When comparing the three indoor environments, water decomposition appears to be the fastest, but the method of analysis for this study determines that using decomposition scales to analyze such environments may produce statistically insignificant results. For this study, piglets were put in a dry steel tub, a water filled steel tub, and a suitcase. These were recorded using photographs for 25 days and then scored using decomposition scales. The total score was divided by all points possible to show a percentage of decomposition and was compared between three different scales using statistical analysis. Therefore, relying on decomposition scales as the only forensic analysis for decomposition to observe how different environments affect cadavers may be problematic, as bodies found indoors tend to be in the early stages of decomposition. The statistical insignificance of the total body score further suggests decomposition scales and postmortem interval methods that use these scales should not be used alone for courtroom purposes, and medicolegal investigators need to apply other scientific methods in order to support their postmortem interval theory