A Stochastic Approach to the Construction of One-Dimensional Chaotic Maps with Prescribed Statistical Properties

We use a recently found parametrization of the solutions of the inverse Frobenius-Perron problem within the class of complete unimodal maps to develop a Monte-Carlo approach for the construction of one-dimensional chaotic dynamical laws with given statistical properties, i.e. invariant density and autocorrelation function. A variety of different examples are presented to demonstrate the power of our method.Comment: to appear in Physics Letters

Faraday Rotation Distributions from Stellar Magnetism in Wind-Blown Bubbles

Faraday rotation is a valuable tool for detecting magnetic fields. Here the technique is considered in relation to wind-blow bubbles. In the context of spherical winds with azimuthal or split monopole stellar magnetic field geometries, we derive maps of the distribution of position angle (PA) rotation of linearly polarized radiation across projected bubbles. We show that the morphology of maps for split monopole fields are distinct from those produced by the toroidal field topology; however, the toroidal case is the one most likely to be detectable because of its slower decline in field strength with distance from the star. We also consider the important case of a bubble with a spherical sub-volume that is field-free to approximate crudely a "swept-up" wind interaction between a fast wind (or possibly a supernova ejecta shell) overtaking a slower magnetized wind from a prior state of stellar evolution. With an azimuthal field, the resultant PA map displays two arc-like features of opposite rotation measure, similar to observations of the supernova remnant G296.5+10.0. We illustrate how PA maps can be used to disentangle Faraday rotation contributions made by the interstellar medium versus the bubble. Although our models involve simplifying assumptions, their consideration leads to a number of general robust conclusions for use in the analysis of radio mapping datasets.Comment: Astrophysical Journal, accepte

Simulation System for the Wendelstein 7-X Safety Control System

The Wendelstein 7-X (W7-X) Safety Instrumented System (SIS) ensures personal safety and investment protection. The development and implementation of the SIS are based on the international safety standard for the process industry sector, IEC 61511. The SIS exhibits a distributed and hierarchical organized architecture consisting of a central Safety System (cSS) on the top and many local Safety Systems (lSS) at the bottom. Each technical component or diagnostic system potentially hazardous for the staff or for the device is equipped with an lSS. The cSS is part of the central control system of W7-X. Whereas the lSSs are responsible for the safety of each individual component, the cSS ensures safety of the whole W7-X device. For every operation phase of the W7-X experiment hard- and software updates for the SIS are mandatory. New components with additional lSS functionality and additional safety signals have to be integrated. Already established safety functions must be adapted and new safety functions have to be integrated into the cSS. Finally, the safety programs of the central and local safety systems have to be verified for every development stage and validated against the safety requirement specification. This contribution focuses on the application of a model based simulation system for the whole SIS of W7-X. A brief introduction into the development process of the SIS and its technical realization will be give followed by a description of the design and implementation of the SIS simulation system using the framework SIMIT (Siemens). Finally, first application experiences of this simulation system for the preparation of the SIS for the upcoming operation phase OP 1.2b of W7-X will be discussed

Analytical solutions to one-dimensional dissipative and discrete chaotic dynamics

Analytical solutions to the chaotic and ergodic motion of a certain class of one-dimensional dissipative and discrete dynamical systems are derived. This allows us to obtain exact expressions for physical properties like the time correlation function. We illustrate our solutions by means of a few examples for which conventional numerical trajectory calculations fail to predict the correct behaviour.Comment: 7 pages and 5 figures, submitted to Phys.Rev.

Miocene orographic uplift forces rapid hydrological change in the southern central Andes

Rainfall in the central Andes associated with the South American Monsoon and the South American Low-Level Jet results from orographic effects on atmospheric circulation exerted by the Andean Plateau and the Eastern Cordillera. However, despite its importance for South American climate, no reliable records exist that allow decoding the evolution of thresholds and interactions between Andean topography and atmospheric circulation, especially regarding the onset of humid conditions in the inherently dry southern central Andes. Here, we employ multi-proxy isotope data of lipid biomarkers, pedogenic carbonates and volcanic glass from the Eastern Cordillera of NW Argentina and present the first long-term evapotranspiration record. We find that regional eco-hydrology and vegetation changes are associated with initiation of moisture transport via the South American Low-Level Jet at 7.6 Ma, and subsequent lateral growth of the orogen at 6.5 Ma. Our results highlight that topographically induced changes in atmospheric circulation patterns, not global climate change, were responsible for late Miocene environmental change in this part of the southern hemisphere. This suggests that mountain building over time fundamentally controlled habitat evolution along the central Andes.Fil: Rohrmann, Alexander. Universitat Potsdam; AlemaniaFil: Sachse, Dirk. Universitat Potsdam; Alemania. German Research Centre for Geosciences; AlemaniaFil: Mulch, Andreas. Goethe Universitat Frankfurt; AlemaniaFil: Pingel, Heiko. Universitat Potsdam; AlemaniaFil: Tofelde, Stefanie. Universitat Potsdam; AlemaniaFil: Alonso, Ricardo Narciso. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Salta. Facultad de Ciencias Naturales; ArgentinaFil: Strecker, Manfred R.. Universitat Potsdam; Alemani

Yrkesidentitet i sjukvård position, person och kön

To improve opportunities for targeted organizational development work in the Swedish health-care sector, the occupation-specific and shared problems of physicians, registered nurses and assistant nurses were examined in a project called "Occupational Identity in Health Care". The aim of the project was : in the light of the prevailing work-organizational setting and gender structure in Swedish health care : to provide a picture of the occupational identities of physicians, registered nurses, and assistant nurses. The point of departure for the investigation was that identity formation is a process of identification and differentiation that takes place in constantly ongoing negotiations and reconstructions within various routine social contexts. Actions and experiences : based in part on shared collegial conceptions concerning frames of reference for the work, and in part on internal principles of practice : have, in terms of their person and position orientation, been interpreted as expressions of occupational identity. Results are based on data obtained from participant observations, diaries and interviews, all of which have been subjected to content analysis. The study shows that there are major contrasts between the occupational identities of physicians, registered nurses, and assistant nurses. Physicians relate to the organization and describe their work from a perspective that has their own occupational position in focus; registered nurses have both a "person" and a "position" perspective; while assistant nurses virtually exclusively adopt a stance based on their own person. The study suggests that a historically conditioned process : one that sustains occupational inequalities in health care : lives on through the mutual conception that the occupations concerned can be defined within a medically defined hierarchy. The expressions of physicians and registered nurses reveal that they see their positions within the confines of a linear, hierarchical system. with the feature that the skills of their own occupational groups both encompass and build upon those of another. By contrast, assistant nurses : as an analogy to their person orientation : regard their position as "invisible", with few concrete features apart from that of being "the lowest". This disguises the fact that there is a considerable degree of parallelism, in the sense of there being skills that are different in kind between the occupations, and that the expertise possessed at the lowest "female" level is not afforded scope to develop and be integrated into the organization. The study offers no evidence of any kind to justify the division of work between the genders that currently prevails. For an efficient health-care organization to be possible, "occupational cultures" must encounter and be more equally integrated into the organization. This has to take place on the terms of direct carers to a far greater extent than has hitherto been the case. In turn, it requires fundamental structural and attitudinal change, which : so far : has seldom been taken as a point of departure for work for change and development in the health-care arena.För att öka förutsättningarna för målinriktat utvecklingsarbete inom sjukvården har läkares, sjuksköterskors och undersköterskors specifika och gemensamma problem och arbetsvillkor studerats i projektet "Yrkesidentitet i Sjukvård". Projektet syftade till, att mot bakgrund av den rådande arbetsorganisatoriska kontexten och könsstrukturen i sjukvården, ge en bild av läkares, sjuksköterskors och undersköterskors yrkesidentiteter. Undersökningens utgångspunkt var att identitetsbildning är en process av identifikation och differentiering, vilken sker i ständiga förhandlingar och rekonstruktioner i olika rutinmässiga sociala sammanhang. Handlingar och upplevelser, som utgår ifrån dels kollegialt delade föreställningar om referensramarna för arbetet, dels inre principer för praktiken, har i termer av person- och positionsorientering tolkats som uttryck för yrkesidentitet. Resultaten baseras på data från deltagande observationer, dagböcker och intervjuer, vilka analyserats med avseende på meningsinnehåll. Undersökningen visar att "läkarens", "sjuksköterskans" och "undersköterskans" yrkesidentiteter starkt skiljer sig åt. Läkaren förhåller sig till organisationen och beskriver sin arbetssituation utifrån ett perspektiv som har den egna yrkesmässiga positionen i fokus, sjuksköterskan utifrån både sin position och sin person medan undersköterskan nästan uteslutande använder ett perspektiv som utgår ifrån den egna personen. Undersökningen visar att en historiskt betingad process, av att upprätthålla skillnad i sjukvården, bl a fortlever genom den ömsesidiga föreställningen om att yrkena kan inordnas i en medicinskt definierad hierarki. Läkaren och sjuksköterskan ger uttryck för att de ser sina positioner i ett linjärt, hierarkiskt system, som utmärks av att den egna yrkeskategorins kompetens inkluderar och bygger på en annans. Undersköterskan upplever, i analogi med sin personorientering, sin position som "osynlig" med få konkreta karakteristiska annat än som "den lägsta". Detta osynliggör att det finns en betydande grad av parallellitet, i bemärkelsen artskilda kompetenser, mellan yrkena och att den kunskap, som finns på den lägsta "kvinnliga" nivån, inte bereds utrymme för att i den positionen utvecklas och integreras i organisationen. Undersökningen ger vidare inga belägg för att det skulle finnas skäl som talar för den i sjukvården rådande könsarbetsdelningen. För att möjliggöra en effektiv organisation måste "yrkeskulturerna" mötas och integreras. I sjukvården gäller att detta mer måste ske på vårdarbetarnas villkor än vad som hittills varit fallet. För detta krävs grundläggande strukturella och attitydmässiga förändring, vilket hittills sällan har tagits som utgångspunkt för förändringsarbete i sjukvården

Influencing European Corn Borer (Lepidoptera: Crambidae) Aggregation Sites in Small Grain Crops

Reliable methods to attract European corn borer, Ostrinia nubilalis (Hübner), adults to small grain crops could be used to aggregate moths into small well-defined areas for control purposes or could be used in a resistance management program for delaying potential O. nubilalis resistance to transgenic corn. The objective of this research was to determine whether small-grain crops could be managed to influence O. nubilalis aggregation behavior. In farmer-managed oat, Atena sativa (L.), fields, more O. nubilalis adults were attracted to high-density patches of oat compared with standard patches of oat; no difference was found between patches of high-density oat and brome, Bromus spp. Numbers of O. nubilalis moths found in 6 barley, Hordeum vulgare (L.), and legume treatments (1995), and 4 oat/legume treatments (1996) were significantly different. The highest number of O. nubilalis adults were observed in barley planted with alfalfa, Medicago sativa (L.), followed by barley planted with crimson clover, Trifolium incarnatum(L.), barley planted with berseem, Trifolium alexandrinum (L.), barley planted with black medic, Medicago lupulina (L.), barley alone, and barley planted with lespedeza, Lespedeza stipulacea (Maximowicz). Double-planted oat attracted the highest number of O. nubilalis adults followed by oat planted with crimson clover, oat planted with alfalfa, and single-planted oat. Each study suggests that there is a positive correlation between moth aggregation and canopy area. Suggestions are made that timing canopy closure of a small-grain crop with peak O. nubilalis flight should maximize O. nubilalis aggregation and should thereby increase the efficacy of any control measures

Effects of correlated covariates on the efficiency of matching and inverse probability weighting estimators for causal inference

In observational studies the overall aim when fitting a model for the propensity score is to reduce bias for an estimator of the causal effect. For this purpose guidelines for covariate selection for propensity score models have been proposed in the causal inference literature. To make the assumption of an unconfounded treatment plausible researchers might be tempted to include many, possibly correlated, covariates in the propensity score model. In this paper we study how the efficiency of matching and inverse probability weighting estimators for average causal effects change when the covariates are correlated. We investigate the case with multivariate normal covariates and linear models for the propensity score and potential outcomes and show results under different model assumptions. We show that the correlation can both increase and decrease the large sample variances of the estimators, and that the corrrelation affects the efficiency of the estimators differently, both with regard to direction and magnitude. Moreover, the strength of the confounding towards the outcome and the treatment plays an important role