A study of large-bowel volvulus in urban Australia

Background: Large-bowel volvulus is a rare cause of bowel obstruction in the industrialized world. We analyzed the presentation and outcome of 49 patients at the Princess Alexandra Hospital, Brisbane, Australia, who received a diagnosis of colonic volvulus from 1991 to 2001. Methods: A retrospective chart study was carried out. Results: Twenty-nine patients had sigmoid volvulus (59%), 19 patients had cecal volvulus (39%) and 1 patient had a transverse colon volvulus (2%). The diagnosis of sigmoid volvulus was made accurately on plain abdominal radiography or contrast enema in 90% of cases (n = 26), compared with only 42% of cases (n = 8) of cecal volvulus. Twenty-two patients with sigmoid volvulus were treated initially with endoscopic decompression. The success rate was 64% (n = 14). There was a high early recurrence rate of sigmoid volvulus for those treated by endoscopic decompression alone (43%) during a mean period of 32 days. Of the 14 patients with cecal volvulus who were treated with right hemicolectomy, 12 had primary anastomosis and 2 had end ileostomy with mucous fistula formation. There was no anastomotic leak following right hemicolectomy with primary anastomosis, even though 6 of these patients had an ischemic cecum. Conclusions: Endoscopic decompression of the sigmoid volvulus was safe and effective as an initial treatment but has a high early recurrence rate. Any patient who is fit enough to undergo operation should have a definitive procedure during the same admission to avoid recurrence. Cecal volvulus is associated with a higher incidence of gangrene and is treated effectively by right hemicolectomy with or without anastomosis. The need for swift operative intervention is emphasized.

The importance of forest area and configuration relative to local habitat factors for conserving forest mammals: A case study of koalas in Queensland, Australia

The loss and fragmentation of forest habitats by human land use are recognised as important factors influencing the decline of forest-dependent fauna. Mammal species that are dependent upon forest habitats are particularly sensitive to habitat loss and fragmentation because they have highly specific habitat requirements, and in many cases have limited ability to move through and utilise the land use matrix. We addressed this problem using a case study of the koala (Phascolarctos cinereus) surveyed in a fragmented rural-urban landscape in southeast Queensland, Australia. We applied a logistic modelling and hierarchical partitioning analysis to determine the importance of forest area and its configuration relative to site (local) and patch-level habitat variables. After taking into account spatial auto-correlation and the year of survey, we found koala occurrence increased with the area of all forest habitats, habitat patch size and the proportion of primary Eucalyptus tree species; and decreased with mean nearest neighbour distance between forest patches, the density of forest patches, and the density of sealed roads. The difference between the effect of habitat area and configuration was not as strong as theory predicts, with the configuration of remnant forest becoming increasingly important as the area of forest habitat declines. We conclude that the area of forest, its configuration across the landscape, as well as the land use matrix, are important determinants of koala occurrence, and that habitat configuration should not be overlooked in the conservation of forest-dependent mammals, such as the koala. We highlight the implications of these findings for koala conservation. (c) 2006 Elsevier Ltd. All rights reserved.

An empirical study of Hoelfding Racing for model selction in K-nearest neighbor classification

Racing algorithms have recently been proposed as a general-purpose method for performing model selection in machine teaming algorithms. In this paper, we present an empirical study of the Hoeffding racing algorithm for selecting the k parameter in a simple k-nearest neighbor classifier. Fifteen widely-used classification datasets from UCI are used and experiments conducted across different confidence levels for racing. The results reveal a significant amount of sensitivity of the k-nn classifier to its model parameter value. The Hoeffding racing algorithm also varies widely in its performance, in terms of the computational savings gained over an exhaustive evaluation. While in some cases the savings gained are quite small, the racing algorithm proved to be highly robust to the possibility of erroneously eliminating the optimal models. All results were strongly dependent on the datasets used.

The Desert of the Real in Spec Ops: The Line. A Study of Simultaneous Hyperreal Experiences by Protagonist and Player : A Study of Simultaneous Hyperreal Experiences by Protagonist and Player

As an anomaly on the market of military shooters of the 21st century, Spec Ops: The Line entails a journey of undetermined realities and modern warfare consequences. In this study, the narrative is analyzed from the perspective of Jean Baudrillard’s idea that simulations have replaced our conception of reality. Both the protagonist and the player of Spec Ops will unavoidably descend into a state of the hyperreal. They experience multiple possible realities within the game narrative and end up unable to comprehend what has transpired. The hyperreal is defined as the state in which it is impossible to discern reality from simulation. The simulation of reality has proliferated itself into being the reality, and the original has been lost. The excessive use of violence, direct approach of the player through a break with the 4th wall and a deceitful narrator contribute to this loss of reality within the game. Although the game represents simulacra, being a simulation in itself, the object of study is the coexisting state of hyperreal shared between protagonist and player when comprehending events in the game. In the end, neither part can understand or discern with any certainty what transpired within the game.

A study of strategic HR issues in an Asian context

Examines five strategic human resource management (HRM) issues using a qualitative methodology. Two of these are related to the central organisational-level constructs of structure and culture. The other three pertain to HR strategy, HR competencies, and HR outsourcing. The study employed the multiple-case design method proposed by Yin, with a view to extending theory in strategic HRM research. Semi-structured interviews were conducted with 35 managers (CEOs, line managers, and HR managers) of nine companies from two major industries in the manufacturing sector – electronic products and machinery/equipment. The research found that top management enlightenment and level of HR competencies together determine the role and status of the HR function in organisations, and that the companies studied pursue four types of HR strategies: informal and not communicated; informal and communicated; formal but not communicated; and formal and communicated. HR strategy was found to affect both vertical and horizontal fits of the HR function. Culture, HR strategy and HR competencies influenced organisational propensity to outsource HR activities.

Getting the most out of multidisciplinary teams: a multi-sample study of team innovation in health care

Driven by the assumption that multidisciplinarity contributes positively to team outcomes teams are often deliberately staffed such that they comprise multiple disciplines. However, the diversity literature suggests that multidisciplinarity may not always benefit a team. This study departs from the notion of a linear, positive effect of multidisciplinarity and tests its contingency on the quality of team processes. It was assumed that multidisciplinarity only contributes to team outcomes if the quality of team processes is high. This hypothesis was tested in two independent samples of health care workers (N = 66 and N = 95 teams), using team innovation as the outcome variable. Results support the hypothesis for the quality of innovation, rather than the number of innovations introduced by the teams.

A quantitative study of the pathological changes in cortical neurons in sporadic Creutzfeldt-Jakob disease

The frequency of morphological abnormalities in neuronal perikarya was studied in the cerebral cortex in cases of sporadic CJD (sCJD) and in elderly control patients. Three hypotheses were tested, namely that the proportion of neurons exhibiting abnormal morphology was increased: (i) in sCJD compared with control patients; (ii) in sCJD, in areas with significant prion protein (PrP) deposition compared with regions with little or no PrP deposition; and (iii) when neurons were spatially associated with a PrP deposit compared with neurons between PrP deposits. Changes in cell shape (swollen or atrophic cell bodies), nuclei (displaced, indistinct, shrunken or absent nuclei; absence of nucleolus), and cytoplasm (dense or pale cytoplasm, PrP positive cytoplasm, vacuolation) were commonly observed in all of the cortical areas studied in the sCJD cases. The proportion of neurons exhibiting each type of morphological change was significantly increased in sCJD compared with age-matched control cases. In sCJD, neuronal abnormalities were present in areas with little PrP deposition, but at significantly lower frequencies compared with areas with significant densities of PrP deposits. Abnormalities of cell shape, nucleus and the presence of cytoplasmic vacuolation were increased when the neurons were associated with a PrP deposit, but fewer of these neurons were PrP-positive compared with neurons between deposits. The data suggest significant neuronal degeneration in the cerebral cortex in sCJD in areas without significant PrP deposition and a further phase of neuronal degeneration associated with the appearance of PrP deposits.

A study of inputs and their influence on technological innovative activity

Technological innovation has been widely studied: however surprisingly little is known about the experience of managing the process. Most reports tend to be generalistic and/or prescriptive whereas it is argued that multiple sources of variation in the process limit the value of these. A description of the innovation process is given together with a presentation of what is knovrn from existing studies. Gaps identified in this area suggest that a variety of organisational influences are important and an attempt is made to identify some of these at individual, group and organisational level. A simple system model of the innovation management process is developed. Further investigation of the influence of these factors was made possible through an extended on-site case study. Methodology for this based upon participant observation coupled wth a wide and flexible range of techniques is described. Evidence is presented about many aspects of the innovation process from a number of different levels and perspectives: the attempt is to demonstrate the extent to which variation due to contingent influences takes place. It is argued that problems identified all relate to the issue of integration. This theme is also developed from an analytical viewoint and it is suggested that organisational response to increases in complexity in the external environment will be to match them with internal complexity. Differentiation of this kind will require extensive and flexible integration, especially in those inherently uncertain areas associated with innovation. Whilst traditionally a function of management, it is argued that integration needs have increased to the point where a new specialism is required. The concept of integration specialist is developed from this analysis and attempts at simple integrative change during the research are described. Finally a strategy for integration - or rather for building in integrative capability - ln the organisation studied is described.

Structure and dynamics of multiple cationic vectors-siRNA complexation by all-atomic molecular dynamics simulations

Understanding the molecular mechanism of gene condensation is a key component to rationalizing gene delivery phenomena, including functional properties such as the stability of the gene-vector complex and the intracellular release of the gene. In this work, we adopt an atomistic molecular dynamics simulation approach to study the complexation of short strand duplex RNA with four cationic carrier systems of varying charge and surface topology at different charge ratios. At lower charge ratios, polymers bind quite effectively to siRNA, while at high charge ratios, the complexes are saturated and there are free polymers that are unable to associate with RNA. We also observed reduced fluctuations in RNA structures when complexed with multiple polymers in solution as compared to both free siRNA in water and the single polymer complexes. These novel simulations provide a much better understanding of key mechanistic aspects of gene-polycation complexation and thereby advance progress toward rational design of nonviral gene delivery systems.

Proteomics in the study of hippocampal plasticity

Synaptic plasticity is the dynamic regulation of the strength of synaptic communication between nerve cells. It is central to neuronal development as well as experience-dependent remodeling of the adult nervous system as occurs during memory formation. Aberrant forms of synaptic plasticity also accompany a variety of neurological and psychiatric diseases, and unraveling the biological basis of synaptic plasticity has been a major goal in neurobiology research. The biochemical and structural mechanisms underlying different forms of synaptic plasticity are complex, involving multiple signaling cascades, reconfigurations of structural proteins and the trafficking of synaptic proteins. As such, proteomics should be a valuable tool in dissecting the molecular events underlying normal and disease-related forms of plasticity. In fact, progress in this area has been disappointingly slow. We discuss the particular challenges associated with proteomic interrogation of synaptic plasticity processes and outline ways in which we believe proteomics may advance the field over the next few years. We pay particular attention to technical advances being made in small sample proteomics and the advent of proteomic imaging in studying brain plasticity.

Quantitative variations in the pathology of 11 cases of variant Creutzfeldt-Jakob disease (vCJD)

Quantitative variations in the density and distribution of the vacuolation ('spongiform change'), surviving neurons, and prion protein (PrP) deposits were studied in eight brain regions from 11 cases of variant Creutzfeldt-Jakob disease (vCJD). Principal components analysis (PCA) was used to study the similarities and differences between cases and to identify the neuropathological variables which could best account for these variations. Two principal components (PC) were extracted from the data accounting in total for 93.4% of the variance; the majority of the variance (90%) being associated with PC1. Some clustering of the 11 cases in relation to PC1 and PC2 was evident. The densities of the vacuolation in the occipital cortex and the molecular layer of the cerebellum were positively and negatively correlated, respectively, with PC1. No significant variation between cases was associated with PrP deposition. These data suggest that vCJD cases have a consistent neuropathological profile characterised by the presence of vacuolation, neuronal loss and PrP deposition in the form of florid and non-florid deposits. However, there are quantitative variations between cases in the development of the vacuolation especially affecting the occipital cortex and cerebellum. © 2002 Elsevier Science Ireland Ltd. All rights reserved.

Surface wave techniques for the study of engineering structures and materials

A wire drive pulse echo method of measuring the spectrum of solid bodies described. Using an 's' plane representation, a general analysis of the transient response of such solids has been carried out. This was used for the study of the stepped amplitude transient of high order modes of disks and for the case where there are two adjacent resonant frequencies. The techniques developed have been applied to the measurenent of the elasticities of refractory materials at high temperatures. In the experimental study of the high order in-plane resonances of thin disks it was found that the energy travelled at the edge of the disk and this initiated the work on one dimensional Rayleigh waves.Their properties were established for the straight edge condition by following an analysis similar to that of the two dimensional case. Experiments were then carried out on the velocity dispersion of various circuits including the disk and a hole in a large plate - the negative curvature condition.Theoretical analysis established the phase and group velocities for these cases and experimental tests on aluminium and glass gave good agreement with theory. At high frequencies all velocities approach that of the one dimensional Rayleigh waves. When applied to crack detection it was observed that a signal burst travelling round a disk showed an anomalous amplitude effect. In certain cases the signal which travelled the greater distance had the greater amplitude.An experiment was designed to investigate the phenanenon and it was established that the energy travelled in two nodes with different velocities.It was found by analysis that as well as the Rayleigh surface wave on the edge, a seoond node travelling at about the shear velocity was excited and the calculated results gave reasonable agreement with the experiments.

Principal components analysis of Alzheimer’s disease based on neuropathological data: A study of 79 patients

A Principal Components Analysis of neuropathological data from 79 Alzheimer’s disease (AD) cases was performed to determine whether there was evidence for subtypes of the disease. Two principal components were extracted from the data which accounted for 72% and 12% of the total variance respectively. The results suggested that 1) AD was heterogeneous but subtypes could not be clearly defined; 2) the heterogeneity, in part, reflected disease onset; 3) familial cases did not constitute a distinct subtype of AD and 4) there were two forms of late onset AD, one of which was associated with less senile plaque and neurofibrillary tangle development but with a greater degree of brain atherosclerosis.

Community-Based Study of the Association of High Myopia in Children with Ocular and Systemic Disease

Purpose. High myopia in childhood is associated with important ocular and systemic conditions. However in the UK, high myopia in early childhood is not specifically identified in current ophthalmology, optometry, or orthoptic protocols for screening, referral, or investigation. An ongoing study in the West Midlands, UK, is investigating high myopia presenting to community health care clinics with the aim of compiling guidelines for assessment and subsequent referral. Methods. Children with high myopia were identified from community optometric and orthoptic sources and invited for an ophthalmology and optometry examination to ascertain possible ocular or systemic disease. Results. High myopia with no associated ocular or systemic condition was present in 15 (56%) of the children. In seven children (25%), associated ocular problems were found including unrecognized retinal dystrophies and amblyopia. Systemic disorders associated with high myopia were found in five children (19%) and included Sticklers syndrome, Weill-Marchesani syndrome, and homocystinuria. In one child, the diagnosis made before this study was found to be incorrect, and in another child, the results were inconclusive. In two cases, the diagnosis of a systemic condition in the child led to the identification of the disease in at least one relative. Conclusions. There is a high prevalence of ocular and systemic abnormality in young children seen in the community. Optometric and ophthalmologic assessment of children less than 10 years with myopia ≥5 D is likely to identify significant ocular or systemic disease, a proportion of which will respond to medical intervention. Detection and prompt referral of these cases by community health care services may be expected to prolong vision and possibly life expectancy.

Principal components analysis of Alzheimer's disease based on neuropathological data: a study of 79 patients

A principal components analysis was carried out on neuropathological data collected from 79 cases of Alzheimer's disease (AD) diagnosed in a single centre. The purpose of the study was to determine whether on neuropathological criteria there was evidence for clearly defined subtypes of the disease. Two principal components (PC1 and PC2) were extracted from the data. PC1 was considerable more important than PC2 accounting for 72% of the total variance. When plotted in relation to the first two principal components the majority of cases (65/79) were distributed in a single cluster within which subgroupings were not clearly evident. In addition, there were a number of individual, mainly early-onset cases, which were neither related to each other nor to the main cluster. The distribution of each neuropathological feature was examined in relation to PC1 and 2, Disease onset, rhe degree of gross brain atrophy, neuronal loss and the devlopment of senile plaques (SP) and neurofibrillary tangles (NFT) were negatively correlated with PC1. The devlopment of SP and NFT and the degree of brain athersclerosis were positively correlated with PC2. These results suggested: 1) that there were different forms of AD but no clear division of the cases into subclasses could be made based on the neuropathological criteria used; the cases showing a more continuous distribution from one form to another, 2) that disease onset was an important variable and was associated with a greater development of pathological changes, 3) familial cases were not a distinct subclass of AD; the cases being widely distributed in relation to PC1 and PC2 and 4) that there may be two forms of late-onset AD whic grade into each other, one of which was associated with less SP and NFT development but with a greater degree of brain atherosclerosis.