Homogeneous variational problems: a minicourse

A Finsler geometry may be understood as a homogeneous variational problem, where the Finsler function is the Lagrangian. The extremals in Finsler geometry are curves, but in more general variational problems we might consider extremal submanifolds of dimension $m$. In this minicourse we discuss these problems from a geometric point of view.Comment: This paper is a written-up version of the major part of a minicourse given at the sixth Bilateral Workshop on Differential Geometry and its Applications, held in Ostrava in May 201

Bayes-X: a Bayesian inference tool for the analysis of X-ray observations of galaxy clusters

We present the first public release of our Bayesian inference tool, Bayes-X, for the analysis of X-ray observations of galaxy clusters. We illustrate the use of Bayes-X by analysing a set of four simulated clusters at z=0.2-0.9 as they would be observed by a Chandra-like X-ray observatory. In both the simulations and the analysis pipeline we assume that the dark matter density follows a spherically-symmetric Navarro, Frenk and White (NFW) profile and that the gas pressure is described by a generalised NFW (GNFW) profile. We then perform four sets of analyses. By numerically exploring the joint probability distribution of the cluster parameters given simulated Chandra-like data, we show that the model and analysis technique can robustly return the simulated cluster input quantities, constrain the cluster physical parameters and reveal the degeneracies among the model parameters and cluster physical parameters. We then analyse Chandra data on the nearby cluster, A262, and derive the cluster physical profiles. To illustrate the performance of the Bayesian model selection, we also carried out analyses assuming an Einasto profile for the matter density and calculated the Bayes factor. The results of the model selection analyses for the simulated data favour the NFW model as expected. However, we find that the Einasto profile is preferred in the analysis of A262. The Bayes-X software, which is implemented in Fortran 90, is available at http://www.mrao.cam.ac.uk/facilities/software/bayesx/.Comment: 22 pages, 11 figure

Improvements in the Colorado ammonia model by simultaneous computations of extremes in flow and water chemistry

November 1993.This publication is a product of the Natural Resources Law Center, a research and public education center at the University of Colorado School of Law.Includes bibliographical references (page 18).The present study reports the results of an analysis of association for extremes in pH, temperature, and low flow at 12 sites in Colorado for which an extensive data record is available (21 years at 12 or more samples per year). Statistical study of data for these sites showed no general relationship between flow and percent unionized ammonia at any station. Within periods of low flow, there was no parametric association between percent unionized ammonia and low flow. A nonparametric test of association between percent unionized ammonia and low flows that 8 of the stations have a random association of the two variables, i.e., the expected value of percent unionized ammonia during a period of low flow is equal to the mean value rather than an extreme value. At four of the stations, the association of low flow with percent unionized ammonia was nonrandom. Three of these showed a negative association, i.e., the percent unionized ammonia was significantly lower than the mean during periods of low flow. At a single station (the South Platte River near Kersey), there was a significant positive association, albeit a rather loose one, between percent unionized ammonia and extreme low flows; the lowest 5th percentile of low-flow values showed a mean of the 77th percentile unionized ammonia. These findings suggest modifications of models that are used in computing maximum total ammonia for permits. The assumption of strong association between the least favorable flows (low flow) and least favorable percent unionized ammonia (high percent unionized ammonia) is not justified by field information and may result in overly stringent ammonia control requirements for point source discharges.Grant no. 14-08-0001-G2008/2, Project no. 12; financed in part by the U.S. Dept. of the Interior, Geological Survey, through the Colorado Water Resources Research Institute

The key elements of success and failure in the NZ kiwifruit industry

The study explores the nature and performance of the New Zealand kiwifruit industry from 1980 to 2006. As almost 94 per cent of kiwifruit produced in New Zealand is exported the focus of this study is on the export sector of the kiwifruit industry. Value chain theory is used to define the kiwifruit industry in New Zealand. The value chain links the key participants and organisations that ultimately bring kiwifruit to consumers. Therefore it incorporates the three main stages from the orchard to market - growing kiwifruit, post harvest operations, and exporting. The examination of the industry since 1980 can be separated into the following key focus areas: 1. changing market characteristics: production trends, target markets, changing consumer preferences and increasing competition. 2. operating environment: how different factors have changed to impact on the industry. 3. industry structure: changes at the firm and industry level in response to changing circumstances and environments. 4. conduct and performance: analysis of broad performance measures, extent of sharing of information, knowledge and resources within the industry, and the degree of interdependence along the value chain. In particular this study explores the kiwifruit industry’s current single desk seller structure – Zespri. It examines how it evolved by looking at the structural developments that preceded its existence and the factors that influenced its formation. It also looks at the recent consolidation amongst post-harvest operators and explores the factors that have bought about this change. It reviews how the industry has responded to changing market conditions by producing new products and how the role of marketing (i.e. branded products) has influenced export turnover.Funded by AGMARDT The Agricultural Marketing Research and Development Trus

Tackling the workforce crisis in district nursing: can the Dutch Buurtzorg model offer a solution and a better patient experience? A mixed methods case study.

Despite policy intentions for more healthcare out of hospital, district nursing services face multiple funding and staffing challenges, which compromise the care delivered and policy objectives. OBJECTIVES: What is the impact of the adapted Buurtzorg model on feasibility, acceptability and effective outcomes in an English district nursing service? DESIGN: Mixed methods case study. SETTING: Primary care. PARTICIPANTS: Neighbourhood nursing team (Buurtzorg model), patients and carers, general practitioners (GPs), other health professionals, managers and conventional district nurses. RESULTS: The adapted Buurtzorg model of community nursing demonstrated feasibility and acceptability to patients, carers, GPs and other health professionals. For many patients, it was preferable to previous experiences of district nursing in terms of continuity in care, improved support of multiple long-term conditions (encompassing physical, mental and social factors) and proactive care. For the neighbourhood nurses, the ability to make operational and clinical decisions at team level meant adopting practices that made the service more responsive, accessible and efficient and offered a more attractive working environment. Challenges were reported by nurses and managers in relation to the recognition and support of the concept of self-managing teams within a large bureaucratic healthcare organisation. While there were some reports of clinical effectiveness and efficiency, this was not possible to quantify, cost or compare with the standard district nursing service. CONCLUSIONS: The adapted Buurtzorg model of neighbourhood nursing holds potential for addressing issues of concern to patients, carers and staff in the community. The two interacting innovations, that is, a renewed focus on patient and carer-centred care and the self-managing team, were implemented in ways that patients, carers, other health professionals and nurses could identify difference for both the nursing care and also the nurses' working lives. It now requires longer term investigation to understand both the mechanism for change and also the sustainability

Derivation of the quantum probability law from minimal non-demolition measurement

One more derivation of the quantum probability rule is presented in order to shed more light on the versatile aspects of this fundamental law. It is shown that the change of state in minimal quantum non-demolition measurement, also known as ideal measurement, implies the probability law in a simple way. Namely, the very requirement of minimal change of state, put in proper mathematical form, gives the well known Lueders formula, which contains the probability rule.Comment: 8 page

An Empirically Based Calculation of the Extragalactic Infrared Background

Using the excellent observed correlations among various infrared wavebands with 12 and 60 micron luminosities, we calculate the 2-300 micron spectra of galaxies as a function of luminosity. We then use 12 micron and 60 micron galaxy luminosity functions derived from IRAS data, together with recent data on the redshift evolution of galaxy emissivity, to derive a new, empirically based IR background spectrum from stellar and dust emission in galaxies. Our best estimate for the IR background is of order 2-3 nW/m^2/sr with a peak around 200 microns reaching 6-8 nW/m^2/sr. Our empirically derived background spectrum is fairly flat in the mid-IR, as opposed to spectra based on modeling with discrete temperatures which exhibit a "valley" in the mid-IR. We also derive a conservative lower limit to the IR background which is more than a factor of 2 lower than our derived flux.Comment: 14 pages AASTeX, 2 .ps figures, the Astrophysical Journal, in pres

Electronic structure of the molecule based magnet Cu PM(NO3)2 (H2O)2

We present density functional calculations on the molecule based S=1/2 antiferromagnetic chain compound Cu PM(NO3)2 (H2O)2; PM = pyrimidine. The properties of the ferro- and antiferromagnetic state are investigated at the level of the local density approximation and with the hybrid functional B3LYP. Spin density maps illustrate the exchange path via the pyrimidine molecule which mediates the magnetism in the one-dimensional chain. The computed exchange coupling is antiferromagnetic and in reasonable agreement with the experiment. It is suggested that the antiferromagnetic coupling is due to the possibility of stronger delocalization of the charges on the nitrogen atoms, compared to the ferromagnetic case. In addition, computed isotropic and anisotropic hyperfine interaction parameters are compared with recent NMR experiments

Interfacing GHz-bandwidth heralded single photons with a room-temperature Raman quantum memory

Photonics is a promising platform for quantum technologies. However, photon sources and two-photon gates currently only operate probabilistically. Large-scale photonic processing will therefore be impossible without a multiplexing strategy to actively select successful events. High time-bandwidth-product quantum memories - devices that store and retrieve single photons on-demand - provide an efficient remedy via active synchronisation. Here we interface a GHz-bandwidth heralded single-photon source and a room-temperature Raman memory with a time-bandwidth product exceeding 1000. We store heralded single photons and observe a clear influence of the input photon statistics on the retrieved light, which agrees with our theoretical model. The preservation of the stored field's statistics is limited by four-wave-mixing noise, which we identify as the key remaining challenge in the development of practical memories for scalable photonic information processing