Theory of tunneling spectroscopy in UPd2Al3

There is still significant debate about the symmetry of the order parameter in the heavy-fermion superconductor UPd$_{2}$Al$_{3}$, with proposals for cos(k3), cos(2k3), sin(k3),and exp(i\phi) sin(k3). Here we analyze the tunneling spectroscopy of this compound and demonstrate that the experimental results by Jourdan et al are inconsistent with the last two order parameters, which are expected to show zero-bias conductance peaks. We propose a definitive tunneling experiment to distinguish between the first two order parameters.Comment: 6 pages, 8 figure

Graded persistence diagrams and persistence landscapes

We introduce a refinement of the persistence diagram, the graded persistence diagram. It is the Mobius inversion of the graded rank function, which is obtained from the rank function using the unary numeral system. Both persistence diagrams and graded persistence diagrams are integer-valued functions on the Cartesian plane. Whereas the persistence diagram takes non-negative values, the graded persistence diagram takes values of 0, 1, or -1. The sum of the graded persistence diagrams is the persistence diagram. We show that the positive and negative points in the k-th graded persistence diagram correspond to the local maxima and minima, respectively, of the k-th persistence landscape. We prove a stability theorem for graded persistence diagrams: the 1-Wasserstein distance between k-th graded persistence diagrams is bounded by twice the 1-Wasserstein distance between the corresponding persistence diagrams, and this bound is attained. In the other direction, the 1-Wasserstein distance is a lower bound for the sum of the 1-Wasserstein distances between the k-th graded persistence diagrams. In fact, the 1-Wasserstein distance for graded persistence diagrams is more discriminative than the 1-Wasserstein distance for the corresponding persistence diagrams.Comment: accepted for publication in Discrete and Computational Geometr

Vulnerability of the agricultural sector to climate change: The development of a pantropical Climate Risk Vulnerability Assessment to inform sub-national decision making

As climate change continues to exert increasing pressure upon the livelihoods and agricultural sector of many developing and developed nations, a need exists to understand and prioritise at the sub national scale which areas and communities are most vulnerable. The purpose of this study is to develop a robust, rigorous and replicable methodology that is flexible to data limitations and spatially prioritizes the vulnerability of agriculture and rural livelihoods to climate change. We have applied the methodology in Vietnam, Uganda and Nicaragua, three contrasting developing countries that are particularly threatened by climate change. We conceptualize vulnerability to climate change following the widely adopted combination of sensitivity, exposure and adaptive capacity. We used Ecocrop and Maxent ecological models under a high emission climate scenario to assess the sensitivity of the main food security and cash crops to climate change. Using a participatory approach, we identified exposure to natural hazards and the main indicators of adaptive capacity, which were modelled and analysed using geographic information systems. We finally combined the components of vulnerability using equal-weighting to produce a crop specific vulnerability index and a final accumulative score. We have mapped the hotspots of climate change vulnerability and identified the underlying driving indicators. For example, in Vietnam we found the Mekong delta to be one of the vulnerable regions due to a decline in the climatic suitability of rice and maize, combined with high exposure to flooding, sea level rise and drought. However, the region is marked by a relatively high adaptive capacity due to developed infrastructure and comparatively high levels of education. The approach and information derived from the study informs public climate change policies and actions, as vulnerability assessments are the bases of any National Adaptation Plans (NAP), National Determined Contributions (NDC) and for accessing climate finance

Red abalone size data from Johnsons Lee, Santa Rosa Island, collected from 1978 to 1984

Red abalone, Haliotis rufescens, were collected at Johnsons Lee, Santa Rosa Island, in the summers of 1978 through 1982, and in 1984, to obtain data for determining various fishery population parameters. Annual visits to the study site were made at yearly intervals to simplify growth calculations. During the first four visits, 2145 red abalones were tagged, measured, and replaced. Shell damage, soft tissue injuries, and causes of mortality were noted. The method of tagging is described. Recovery of first tagged abalone after one year was approximately 30%. Analysis of variance of the annual samples indicated that the samples were, with one exception, not different. Summaries are presented of the number of abalone collected and tagged by year, frequencies of shell damage, soft tissue injury, predatory sponge infestation, and total mortality. Appendices include a listing of the raw size data and various codes for each tagged abalone. (56pp.

Stonehenge remodelled

We are pleased to present the latest account of the sequence of burial and construction at the site of Stonehenge, deduced by its most recent excavators and anchored in time by the application of Bayesian radiocarbon modelling. Five prehistoric stages are proposed, of varied duration, and related by our authors to neighbouring monuments in the Stonehenge environs. While it may never be possible to produce a definitive chronology for this most complex of monuments, the comprehensive and integrated achievement owed to these researchers has brought us much closer to that goal. It is from this firm platform that Stonehenge can begin its new era of communication with the public at large

On bounds and algorithms for frequency synchronization for collaborative communication systems

Cooperative diversity systems are wireless communication systems designed to exploit cooperation among users to mitigate the effects of multipath fading. In fairly general conditions, it has been shown that these systems can achieve the diversity order of an equivalent MISO channel and, if the node geometry permits, virtually the same outage probability can be achieved as that of the equivalent MISO channel for a wide range of applicable SNR. However, much of the prior analysis has been performed under the assumption of perfect timing and frequency offset synchronization. In this paper, we derive the estimation bounds and associated maximum likelihood estimators for frequency offset estimation in a cooperative communication system. We show the benefit of adaptively tuning the frequency of the relay node in order to reduce estimation error at the destination. We also derive an efficient estimation algorithm, based on the correlation sequence of the data, which has mean squared error close to the Cramer-Rao Bound.Comment: Submitted to IEEE Transaction on Signal Processin

How Personal Networks Shape Business : An Anthropological Study of Social Embeddedness, Knowledge Development and Growth of Firms

The research draws from anthropological work on social exchange and later work on embeddedness in an exploration of how personal networks shape business. The purpose of the research is to contribute to an understanding of how social relations shape economic processes and vice versa. The research takes its starting point in small manufacturing firms in southern Sweden primarily in the plastics industry. Internal and external relations of these firms are studied using qualitative methods and formal network analysis. Qualitative methods are used to identify important mechanisms of personal networks. It is argued that personal networks provide a domain of interaction outside short term economic rationality but at the same time, the development of personal networks is fuelled by the need for coordination in achieving business ends. Particularly personal networks are pivotal for gaining access to diverse sets of expertise. Personal networks are shown to be an integral part of both effective production and development in these firms. This is in stark contrast to notions of impersonal markets and bureaucracy that still shape much of discourse on business. Formal network analysis, starting form recurring problems of coordinating production, provides an important complement and expansion of the findings. It becomes evident that certain structures of informal organization provide individuals with means of gaining recognition and a means of navigating a dynamic environment. The same structures are also found to be important for firm development. These networks provide a better basis for acquiring useful information and integrating this meaningfully in the firm. A strong correlation exists between the structure of informal organization and firm growth. The research develops relatively simple methods to differentiate a beneficial informal organization from less beneficial ones in terms of firm development. It also outlines factors shaping the development of beneficial personal network structures in and between firms. These findings, if corroborated in subsequent research, have important implications both for understanding knowledge development and growth of firms and also for understanding how individuals are shaped by the informal structures of their work experience. Hopefully, the research will stimulate further dialogue between anthropology and research on social embeddedness

Bus service reform in Melbourne – the last 5 years

After fifteen years of little change, Melbourne’s bus services have altered significantly in the last five years. Underpinned by policy that supports greater public transport use, reform was driven by three major government programs; SmartBus, minimum standards upgrades and local area service reviews. This paper briefly compares the distribution of each service initiative. Minimum standards upgrades were most widespread, benefiting many middle and outer suburbs. Middle suburbs gained most from SmartBus, especially the City of Manningham where it operates on city as well as orbital routes. And the service reviews were most influential in fringe areas to the west, north and south east. Evaluating the quality of service planning in Melbourne, based on the implementation of recent reviews, is the paper’s main focus. Revised timetables were compared against good planning practice. Significant potential for improved network legibility, efficiency, connectivity with trains and scheduling of multi-route corridors was found and could warrant further work. The extent to which interplay between each program has shaped local networks is also examined. Sometimes programs worked in concert, improving both legibility and service. Other times new routes were simply overlaid on the existing network, reducing legibility and potentially wasting resources. Cases where successful lobbying for marginal routes, unsupported by any program, may have further lowered efficiency are also discussed. The paper concludes that Melbourne has seen significant recent bus service improvements. However it also finds that the quality of service planning has varied and that a more effective network may be possible within existing resources