Assignment methods for incidence calculus

Incidence calculus is a mechanism for probabilistic reasoning in which sets of possible worlds, called incidences, are associated with axioms, and probabilities are then associated with these sets. Inference rules are used to deduce bounds on the incidence of formulae which are not axioms, and bounds for the probability of such a formula can then be obtained. In practice an assignment of probabilities directly to axioms may be given, and it is then necessary to find an assignment of incidence which will reproduce these probabilities. We show that this task of assigning incidences can be viewed as a tree searching problem, and two techniques for performing this research are discussed. One of these is a new proposal involving a depth first search, while the other incorporates a random element. A Prolog implementation of these methods has been developed. The two approaches are compared for efficiency and the significance of their results are discussed. Finally we discuss a new proposal for applying techniques from linear programming to incidence calculus.

Ionic liquids are not always green: hydrolysis of 1-butyl-3-methylimidazolium hexafluorophosphate

1-Butyl-3-methylimidazolium fluoride hydrate has been identified crystallographically as a decomposition product created during purification of the hydrophobic ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate. This highlights the need to treat ionic liquids much as one would any other research chemical with potentially hazardous properties, unknown toxicity and/or stability, particularly when searching for 'green solvents'.

Burrow architecture and digging activity in the Cape dune mole rat

While females are traditionally thought to invest more time and energy into parental care than males, males often invest more resources into searching and displaying for mates, obtaining mates and in male-male conflict. Solitary subterranean mammals perform these activities in a particularly challenging niche, necessitating energetically expensive burrowing to both search for mates and forage for food. This restriction presumably affects males more than females as the former are thought to dig longer tunnels that cover greater distances to search for females. We excavated burrow systems of male and female Cape dune mole rats Bathyergus suillus the, largest truly subterranean mammal, to investigate whether male burrows differ from those of females in ways that reflect mate searching by males. We consider burrow architecture (length, internal dimensions, fractal dimension of tunnel systems, number of nesting chambers and mole mounds on the surface) in relation to mating strategy. Males excavated significantly longer burrow systems with higher fractal dimensions and larger burrow areas than females. Male burrow systems were also significantly farther from one another than females were from other females' burrow systems. However, no sex differences were evident in tunnel cross-sectional area, mass of soil excavated per mound, number of mounds produced per unit burrow length or mass of soil excavated per burrow system. Hence, while males may use their habitat differently from females, they do not appear to differ in the dimensions of the tunnels they create. Thus, exploration and use of the habitat differs between the sexes, which may be a consequence of sex differences in mating behaviour and greater demands for food.

Mutational hotspot in Exon 20 of PIK3CA in breast cancer among Singapore Chinese

The recent identification of somatic mutations in the catalytic region of PIK3 (PIK3CA) in breast cancer and demonstration of their oncogenic function has implicated PIK3CA in mammary carcinogenesis. To investigate possible ethnic differences in patterns of PIK3CA mutations in Singaporean Chinese breast cancer and to characterize these in a panel of cell lines, we sequenced exons 9 and 20 in 80 primary tumors, 19 breast cancer cell lines and 7 normal human mammary epithelial cells (HMECs). Searching for novel hotspots of mutation, we sequenced additional exons ( 1, 2, 6, 7, 14 and 18) in 20 primary tumors and 6 breast cancer cell lines. We detected 33 point mutations in 31 of 80 (39%) breast cancers, and 11 mutations in 10 of 19 (53%) breast cancer cell lines. No mutations were detected in normal breast tissue adjacent to the tumor, or in the 6 normal HMECs. The exon 20 A3140G (H1047R) substitution was identified most frequently (22/31, 71%) and showed a significant association with patient age ( p = 0.043) and stage of the disease ( p = 0.025), but not with ER/PR status or histological grade of the tumor. The incidence of point mutations in PIK3CA, the A3140G substitution in particular, in Singapore breast cancers are among the most frequent reported to date for any gene in breast cancer. The results suggest that mutation of PIK3CA might contribute to development of early stage breast cancer and could provide a potent target for early diagnosis and therapy.

Understanding Accountability in Social Enterprise Organisations: A Framework

Purpose: Social enterprise organisations (SEOs) operate across the boundaries of the public, private and not‐for‐profit (NFP) sectors in delivering public services and competing for resources and legitimacy. While there is a rich literature on accountability in the private and public sectors, together with the wider NFP sector, SEOs have received comparatively little attention and remain a relatively under‐researched organisational form. Drawing on accountability, legitimacy and user‐needs theories, the purpose of this paper is to develop a practical framework which can be used to explore how accountability within SEOs is constructed and discharged.

Design/methodology/approach: This paper draws on user‐needs, accountability, legitimacy and impression management theories expounded in relation to the private, public and NFP sectors.

Findings: A framework to better understand how accountability can be discharged by SEOs is developed and discussed.

Research limitations/implications: While a framework for better understanding SEO accountability is presented, it is not empirically tested. However, the framework has the potential to facilitate a deeper appreciation of the theory and practice of accountability within SEOs and, notwithstanding the inherent difficulties in measuring and managing accountability, could be used to stimulate practitioner involvement.

Practical implications
– As little is known about the current extent of SEO information disclosure or accountability relationships, the framework could be used to assess the discharge of accountability by SEOs, with the findings informing future developments. This should provide useful insights into internal processes and organisational views on accountability bases and mechanisms and can then be used to inform the debate on how SEOs can best discharge their duty to account.

Social implications
– Understanding the nature of SEO accountability reporting has important implications for those involved in advancing the SEO agenda. At a time of public sector cutbacks, and with the government searching for new and more effective ways of delivering services, the role of SEOs in this process is likely to receive greater attention and scrutiny.

Originality/value
– SEOs have grown extensively in size and prominence in recent years and policymakers have come to embrace the role that they play in societal development. This paper responds to a gap in the theoretical literature and contributes to the debate by developing a framework which can be empirically tested. Moreover, it can be used to prompt practitioner involvement and facilitate a better understanding of the complex issues surrounding accounting and accountability in this under‐researched area.

Theory of the Kinetics of Chemical Potentials in Heterogeneous Catalysis

Simple and powerful: The reaction kinetics at surfaces of heterogeneous catalysts is reformulated in terms of the involved chemical potentials. Based on this formulism, an approach of searching for good catalysts is proposed without recourse to extensive calculations of reaction barriers and detailed kinetic analyses. (see picture; R=reactant, I=surface intermediate, P=product, and =standard chemical potential).

Prediction-Based Power-Performance Adaptation of Multithreaded Scientific Codes

Computing has recently reached an inflection point with the introduction of multicore processors. On-chip thread-level parallelism is doubling approximately every other year. Concurrency lends itself naturally to allowing a program to trade performance for power savings by regulating the number of active cores; however, in several domains, users are unwilling to sacrifice performance to save power. We present a prediction model for identifying energy-efficient operating points of concurrency in well-tuned multithreaded scientific applications and a runtime system that uses live program analysis to optimize applications dynamically. We describe a dynamic phase-aware performance prediction model that combines multivariate regression techniques with runtime analysis of data collected from hardware event counters to locate optimal operating points of concurrency. Using our model, we develop a prediction-driven phase-aware runtime optimization scheme that throttles concurrency so that power consumption can be reduced and performance can be set at the knee of the scalability curve of each program phase. The use of prediction reduces the overhead of searching the optimization space while achieving near-optimal performance and power savings. A thorough evaluation of our approach shows a reduction in power consumption of 10.8 percent, simultaneous with an improvement in performance of 17.9 percent, resulting in energy savings of 26.7 percent.

Search for Rapid Changes in the Visible-Light Corona during the 21 June 2001 Total Solar Eclipse

Some 8000 images obtained with the Solar Eclipse Coronal Imaging System (SECIS) fast-frame CCD camera instrument located at Lusaka, Zambia, during the total eclipse of 21 June 2001 have been analysed to search for short-period oscillations in intensity that could be a signature of solar coronal heating mechanisms by MHD wave dissipation. Images were taken in white-light and Fe xiv green-line (5303 ) channels over 205 seconds (frame rate 39 s(-1)), approximately the length of eclipse totality at this location, with a pixel size of four arcseconds square. The data are of considerably better quality than those that we obtained during the 11 August 1999 total eclipse (Rudawy et al.: Astron. Astrophys. 416, 1179, 2004), in that the images are much better exposed and enhancements in the drive system of the heliostat used gave a much improved image stability. Classical Fourier and wavelet techniques have been used to analyse the emission at 29 518 locations, of which 10 714 had emission at reasonably high levels, searching for periodic fluctuations with periods in the range 0.1 -aEuro parts per thousand 17 seconds (frequencies 0.06 -aEuro parts per thousand 10 Hz). While a number of possible periodicities were apparent in the wavelet analysis, none of the spatially and time-limited periodicities in the local brightness curves was found to be physically important. This implies that the pervasive Alfv,n wave-like phenomena (Tomczyk et al.: Science 317, 1192, 2007) using polarimetric observations with the Coronal Multi-Channel Polarimeter (CoMP) instrument do not give rise to significant oscillatory intensity fluctuations.

Core-collapse supernovae in low-metallicity environments and future all-sky transient surveys

Aims. Massive stars in low-metallicity environments may produce exotic explosions such as long-duration gamma-ray bursts and pair-instability supernovae when they die as core-collapse supernovae (CCSNe). Such events are predicted to be relatively common in the early Universe during the first episodes of star-formation. To understand these distant explosions it is vital to study nearby CCSNe arising in low-metallicity environments to determine if the explosions have different characteristics to those studied locally in high-metallicity galaxies. Many of the nearby supernova searches concentrate their efforts on high star-formation rate galaxies, hence biasing the discoveries to metal rich regimes. Here we determine the feasibility of searching for these CCSNe in metal-poor dwarf galaxies using various survey strategies.

Theory of pixel lensing toward M31. II. The velocity anisotropy and flattening of the MACHO distribution

The POINT-AGAPE collaboration is currently searching for massive compact halo objects (MACHOs) toward the Andromeda galaxy (M31). The survey aims to exploit the high inclination of the M31 disk, which causes an asymmetry in the spatial distribution of M31 MACHOs. Here, we investigate the effects of halo velocity anisotropy and flattening on the asymmetry signal using simple halo models. For a spherically symmetric and isotropic halo, we find that the underlying pixel lensing rate in far-disk M31 MACHOs is more than 5 times the rate of near-disk events. We find that the asymmetry is further increased by about 30% if the MACHOs occupy radial orbits rather than tangential orbits, but it is substantially reduced if the MACHOs lie in a flattened halo. However, even for halos with a minor- to major-axis ratio of q = 0.3, the number of M31 MACHOs in the far side outnumber those in the near side by a factor of similar to2. There is also a distance asymmetry, in that the events on the far side are typically farther from the major axis. We show that, if this positional information is exploited in addition to number counts, then the number of candidate events required to confirm asymmetry for a range of flattened and anisotropic halo models is achievable, even with significant contamination by variable stars and foreground microlensing events. For pixel lensing surveys that probe a representative portion of the M31 disk, a sample of around 50 candidates is likely to be sufficient to detect asymmetry within spherical halos, even if half the sample is contaminated, or to detect asymmetry in halos as flat as q = 0.3, provided less than a third of the sample comprises contaminants. We also argue that, provided its mass-to-light ratio is less than 100, the recently observed stellar stream around M31 is not problematic for the detection of asymmetry.

New identifications for blue objects towards the Galactic center: post-AGE stars, Be/disk stars and others

As part of a programme to investigate spatial variations in the Galactic chemical composition, we have been searching for normal B-type stars and A-type supergiants near the Galactic center. During this search we have found eleven peculiar stars, and in some cases performed detailed abundance analyses of them which suggest that they may be at a post-AGB evolutionary stage.

Thalidomide for managing cancer cachexia [review paper]

Cancer cachexia is a multidimensional syndrome characterised by wasting, loss of weight, loss of appetite, metabolic alterations, fatigue and reduced performance status. A significant number of patients with advanced cancer develop cachexia before death. There is no identified optimum treatment for cancer cachexia. While the exact mechanism of the action of thalidomide is unclear, it is known to have immunomodulatory and anti-inflammatory properties, which are thought to help reduce the weight loss associated with cachexia. Preliminary studies of thalidomide have demonstrated encouraging results. This review aimed to (1) evaluate the effectiveness of thalidomide, and (2) identify and assess adverse effects from thalidomide for cancer cachexia. Electronic searches were undertaken in CENTRAL, MEDLINE, EMBASE, Web of Science and CINAHL (from inception to April 2011). Reference lists from reviewed articles, trial registers, relevant conference documents and thalidomide manufacturers identified additional literature. This review included randomised controlled trials (RCTs) and non-RCTs. Participants were adults diagnosed with advanced or incurable cancer and weight loss or a clinical diagnosis of cachexia who were administered thalidomide. All titles and abstracts retrieved by electronic searching were downloaded to a reference management database. Duplicates were removed and the remaining citations were read by two review authors and checked for eligibility. Studies that were deemed ineligible for inclusion had clear reasons for exclusion documented. Data were extracted independently by two review authors for all eligible studies. While a meta-analysis was planned for this review, this was not possible due to the small number of studies included and high heterogeneity among them. Thus a narrative synthesis of the findings is presented. The literature search revealed a dearth of large, well conducted trials in this area. This has hindered the review authors' ability to make an informed decision about thalidomide for the management of cancer cachexia. At present, there is insufficient evidence to refute or support the use of thalidomide for the management of cachexia in advanced cancer patients. The review authors cannot confirm or refute previous literature on the use of thalidomide for patients with advanced cancer who have cachexia and there is inadequate evidence to recommend it for clinical practice. Additional, well conducted, large RCTs are needed to test thalidomide both singularly and in combination with other treatment modalities to ascertain its true benefit, if any, for this population. Furthermore, one study (out of the three reviewed) highlighted that thalidomide was poorly tolerated and its use needs to be explored further in light of the frailty of this population

Enhanced approach for latent semantic indexing using wavelet transform

Latent semantic indexing (LSI) is a technique used for intelligent information retrieval (IR). It can be used as an alternative to traditional keyword matching IR and is attractive in this respect because of its ability to overcome problems with synonymy and polysemy. This study investigates various aspects of LSI: the effect of the Haar wavelet transform (HWT) as a preprocessing step for the singular value decomposition (SVD) in the key stage of the LSI process; and the effect of different threshold types in the HWT on the search results. The developed method allows the visualisation and processing of the term document matrix, generated in the LSI process, using HWT. The results have shown that precision can be increased by applying the HWT as a preprocessing step, with better results for hard thresholding than soft thresholding, whereas standard SVD-based LSI remains the most effective way of searching in terms of recall value.

How do grazers achieve their distribution? A continuum of models from random diffusion to the ideal free distribution using biased random walks

A conceptual model is described for generating distributions of grazing animals, according to their searching behavior, to investigate the mechanisms animals may use to achieve their distributions. The model simulates behaviors ranging from random diffusion, through taxis and cognitively aided navigation (i.e., using memory), to the optimization extreme of the Ideal Free Distribution. These behaviors are generated from simulation of biased diffusion that operates at multiple scales simultaneously, formalizing ideas of multiple-scale foraging behavior. It uses probabilistic bias to represent decisions, allowing multiple search goals to be combined (e.g., foraging and social goals) and the representation of suboptimal behavior. By allowing bias to arise at multiple scales within the environment, each weighted relative to the others, the model can represent different scales of simultaneous decision-making and scale-dependent behavior. The model also allows different constraints to be applied to the animal's ability (e.g., applying food-patch accessibility and information limits). Simulations show that foraging-decision randomness and spatial scale of decision bias have potentially profound effects on both animal intake rate and the distribution of resources in the environment. Spatial variograms show that foraging strategies can differentially change the spatial pattern of resource abundance in the environment to one characteristic of the foraging strategy.</

Optimal diet choice for large herbivores: an extended contingency model

1. A more general contingency model of optimal diet choice is developed, allowing for simultaneous searching and handling, which extends the theory to include grazing and browsing by large herbivores.</p><p>2. Foraging resolves into three modes: purely encounter-limited, purely handling-limited and mixed-process, in which either a handling-limited prey type is added to an encounter-limited diet, or the diet becomes handling-limited as it expands.</p><p>3. The purely encounter-limited diet is, in general, broader than that predicted by the conventional contingency model,</p><p>4. As the degree of simultaneity of searching and handling increases, the optimal diet expands to the point where it is handling-limited, at which point all inferior prey types are rejected,</p><p>5. Inclusion of a less profitable prey species is not necessarily independent of its encounter rate and the zero-one rule does not necessarily hold: some of the less profitable prey may be included in the optimal diet. This gives an optimal foraging explanation for herbivores' mixed diets.</p><p>6. Rules are shown for calculating the boundary between encounter-limited and handling-limited diets and for predicting the proportion of inferior prey to be included in a two-species diet,</p><p>7. The digestive rate model is modified to include simultaneous searching and handling, showing that the more they overlap, the more the predicted diet-breadth is likely to be reduced.</p>