A computational dynamical model of human visual cortex for visual search and feature-based attention

Visual attention can be deployed to locations within the visual array (spatial attention), to individual features such as colour and form (feature-based attention), or to entire objects (object-based attention). Objects are composed of features to form a perceived ‘whole’. This compositional object representation reduces the storage demands by avoiding the need to store every type of object experienced. However, this approach exposes a problem of binding these constituent features (e.g. form and colour) into objects. The problem is made explicit in the higher areas of the ventral stream as information about a feature’s location is absent. For feature-based attention and search, activations flow from the inferotemporal cortex to primary visual cortex without spatial cues from the dorsal stream, therefore the neural effect is applied to all locations across the visual field [79, 60, 7, 52]. My research hypothesis is that biased competition occurs independently for each cued feature, and is implemented by lateral inhibition between a feedforward and a feedback network through a cortical micro-circuit architecture. The local competition for each feature can be combined in the dorsal stream via spatial congruence to implement a secondary spatial attention mechanism, and in early visual areas to bind together the distributed featural representation of a target object

Case mix, outcome and activity for patients admitted to intensive care units requiring chronic renal dialysis: a secondary analysis of the ICNARC Case Mix Programme Database

INTRODUCTION: This report describes the case mix, outcome and activity for admissions to intensive care units (ICUs) of patients who require prior chronic renal dialysis for end-stage renal failure (ESRF), and investigates the effect of case mix factors on outcome. METHODS: This was a secondary analysis of a high-quality clinical database, namely the Intensive Care National Audit & Research Centre (ICNARC) Case Mix Programme Database, which includes 276,731 admissions to 170 adult ICUs across England, Wales and Northern Ireland from 1995 to 2004. RESULTS: During the eight year study period, 1.3% (n = 3,420) of all patients admitted to ICU were receiving chronic renal dialysis before ICU admission. This represents an estimated ICU utilization of six admissions (32 bed-days) per 100 dialysis patient-years. The ESRF group was younger (mean age 57.3 years versus 59.5 years) and more likely to be male (60.2% versus 57.9%) than those without ESRF. Acute Physiology and Chronic Health Evaluation II score and Acute Physiology Score revealed greater severity of illness on admission in patients with ESRF (mean 24.7 versus 16.6 and 17.2 versus 12.6, respectively). Length of stay in ICU was comparable between groups (median 1.9 days versus 1.8 days) and ICU mortality was only slightly elevated in the ESRF group (26.3% versus 20.8%). However, the ESRF group had protracted overall hospital stay (median 25 days versus 17 days), and increased hospital mortality (45.3% versus 31.2%) and ICU readmission (9.0% vs. 4.7%). Multiple logistic regression analysis adjusted for case mix identified the increased hospital mortality to be associated with increasing age, emergency surgery and nonsurgical cases, cardiopulmonary resuscitation before ICU admission and extremes of physiological norms. The adjusted odds ratio for ultimate hospital mortality associated with chronic renal dialysis was 1.24 (95% confidence interval 1.13 to 1.37). CONCLUSION: Patients with ESRF admitted to UK ICUs are more likely to be male and younger, with a medical cause of admission, and to have greater severity of illness than the non-ESRF population. Outcomes on the ICU were comparable between the two groups, but those patients with ESRF had greater readmission rates, prolonged post-ICU hospital stay and increased post-ICU hospital mortality. This study is by far the largest comparative outcome analysis to date in patients with ESRF admitted to the ICU. It may help to inform clinical decision-making and resource requirements for this patient population

Case mix, outcome and activity for patients admitted to intensive care units requiring chronic renal dialysis: a secondary analysis of the ICNARC Case Mix Programme Database

INTRODUCTION: This report describes the case mix, outcome and activity for admissions to intensive care units (ICUs) of patients who require prior chronic renal dialysis for end-stage renal failure (ESRF), and investigates the effect of case mix factors on outcome. METHODS: This was a secondary analysis of a high-quality clinical database, namely the Intensive Care National Audit & Research Centre (ICNARC) Case Mix Programme Database, which includes 276,731 admissions to 170 adult ICUs across England, Wales and Northern Ireland from 1995 to 2004. RESULTS: During the eight year study period, 1.3% (n = 3,420) of all patients admitted to ICU were receiving chronic renal dialysis before ICU admission. This represents an estimated ICU utilization of six admissions (32 bed-days) per 100 dialysis patient-years. The ESRF group was younger (mean age 57.3 years versus 59.5 years) and more likely to be male (60.2% versus 57.9%) than those without ESRF. Acute Physiology and Chronic Health Evaluation II score and Acute Physiology Score revealed greater severity of illness on admission in patients with ESRF (mean 24.7 versus 16.6 and 17.2 versus 12.6, respectively). Length of stay in ICU was comparable between groups (median 1.9 days versus 1.8 days) and ICU mortality was only slightly elevated in the ESRF group (26.3% versus 20.8%). However, the ESRF group had protracted overall hospital stay (median 25 days versus 17 days), and increased hospital mortality (45.3% versus 31.2%) and ICU readmission (9.0% vs. 4.7%). Multiple logistic regression analysis adjusted for case mix identified the increased hospital mortality to be associated with increasing age, emergency surgery and nonsurgical cases, cardiopulmonary resuscitation before ICU admission and extremes of physiological norms. The adjusted odds ratio for ultimate hospital mortality associated with chronic renal dialysis was 1.24 (95% confidence interval 1.13 to 1.37). CONCLUSION: Patients with ESRF admitted to UK ICUs are more likely to be male and younger, with a medical cause of admission, and to have greater severity of illness than the non-ESRF population. Outcomes on the ICU were comparable between the two groups, but those patients with ESRF had greater readmission rates, prolonged post-ICU hospital stay and increased post-ICU hospital mortality. This study is by far the largest comparative outcome analysis to date in patients with ESRF admitted to the ICU. It may help to inform clinical decision-making and resource requirements for this patient population

Th1-type immune responses to Porphyromonas gingivalis antigens exacerbate angiotensin II-dependent hypertension and vascular dysfunction

Background and Purpose: Emerging evidence indicates that hypertension is mediated by immune mechanisms. We hypothesized that exposure to Porphyromonas gingivalis antigens, commonly encountered in periodontal disease, can enhance immune activation in hypertension and exacerbate blood pressure elevation, vascular inflammation and vascular dysfunction. Experimental Approach: Th1 immune response were elicited through immunizations using Porphyromonas gingivalis lysate antigens (10ug) conjugated with aluminium oxide (50ug) and IL‐12 (1ug). The hypertension and vascular endothelial dysfunction evoked by sub‐pressor doses of Angiotensin II (0.25mg/kg/day) were studied and vascular inflammation was quantified by flow cytometry and real time polymerase chain reaction. Key Results: Systemic T cell activation, characteristic for hypertension, was exacerbated by P. gingivalis antigen stimulations. This translated into increased aortic vascular inflammation with enhanced leukocytes, in particular, T cell and macrophage infiltration. Expression of the Th1 cytokines, Interferon‐γ and Tumour Necrosis Factor‐α and the transcription factor TBX21 was increased in aortas of P. gingivalis/Interleukin‐12/aluminium oxide immunized mice, while IL‐4 and TGF‐β were unchanged. These immune changes in mice with induced T helper type 1 immune responses were associated with enhanced blood pressure elevation and endothelial dysfunction compared to control mice in response to two weeks infusion of a sub‐pressor dose of Angiotensin II. Conclusion and Implications: These studies support the concept that Th1 immune responses induced by bacterial antigens such as P. gingivalis can increase sensitivity to sub‐pressor pro‐hypertensive insults such as low dose Angiotensin II, therefore providing a mechanistic link between chronic infection such as periodontitis and hypertension

Early Eocene Arctic volcanism from carbonate-metasomatized mantle

Melilitite, nephelinite, basanite, and alkali basalt, along with phonolite differentiates, form the Freemans Cove Complex (FCC) in the south-eastern extremity of Bathurst Island (Nunavut, Canada). New 40Ar/39Ar chronology indicates their emplacement between ~ 56 and ~ 54 million years ago within a localized extensional structure. Melilitites and nephelinites, along with phonolite differentiates, likely relate to the beginning and end phases of extension, whereas alkali basalts were emplaced during a main extensional episode at ~ 55 Ma. The melilitites, nephelinites, and alkali basalts show no strong evidence for significant assimilation of crust, in contrast to some phonolites. Partial melting occurred within both the garnet- and spinel-facies mantle and sampled sources with He, O, Nd, Hf, and Os isotope characteristics indicative of peridotite with two distinct components. The first, expressed in higher degree partial melts, represents a relatively depleted component (“A”; 3He/4He ~ 8 RA, εNdi ~ + 3 εHfi ~ + 7, γOsi ~ 0). The second was an enriched component (“B” 3He/4He + 70) sampled by the lowest degree partial melts and represents carbonate-metasomatized peridotite. Magmatism in the FCC shows that rifting extended from the Labrador Sea to Bathurst Island and reached a zenith at ~ 55 Ma, during the Eurekan orogeny. The incompatible trace-element abundances and isotopic signatures of FCC rocks indicate melt generation occurred at the base of relatively thin lithosphere at the margin of a thick craton, with no mantle plume influence. FCC melt compositions are distinct from other continental rift magmatic provinces worldwide, and their metasomatized mantle source was plausibly formed synchronously with emplacement of Cretaceous kimberlites. The FCC illustrates that the range of isotopic compositions preserved in continental rift magmas are likely to be dominated by temporal changes in the extent of partial melting, as well as by the timing and degree of metasomatism recorded in the underlying continental lithosphere

Rapid design and manufacture tools in architecture

The continuing development of rapid prototyping technologies and the introduction of concept modelling technologies means that their use is expanding into a greater range of applications. The primary aim of this paper is to give the reader an overview of the current state of the art in layered manufacturing (LM) technology and its applicability in the field of architecture. The paper reports on the findings of a benchmarking study, conducted by the Rapid Design and Manufacturing (RDM) Group in Glasgow [G.J. Ryder, A. McGown, W. Ion, G. Green, D. Harrison, B. Wood, Rapid prototyping feasibility report, Rapid Prototyping Group, Glasgow School of Art, 1998.], which identified that the applicability of LM technologies in any application can be governed by a series of critical process and application specific issues. A further survey carried out by the RDM group investigated current model making practice, current 3D CAD use and current use of LM technologies within the field of architecture. The findings are then compared with the capabilities of LM technologies. Future research needs in this area are identified and briefly outlined

Quadrupling inhaled glucocorticoid dose to abort asthma exacerbations

BACKGROUND Asthma exacerbations are frightening for patients and are occasionally fatal. We tested the concept that a plan for patients to manage their asthma (self-management plan), which included a temporary quadrupling of the dose of inhaled glucocorticoids when asthma control started to deteriorate, would reduce the incidence of severe asthma exacerbations among adults and adolescents with asthma. METHODS We conducted a pragmatic, unblinded, randomized trial involving adults and adolescents with asthma who were receiving inhaled glucocorticoids, with or without add-on therapy, and who had had at least one exacerbation in the previous 12 months. We compared a self-management plan that included an increase in the dose of inhaled glucocorticoids by a factor of 4 (quadrupling group) with the same plan without such an increase (non-quadrupling group), over a period of 12 months. The primary outcome was the time to a first severe asthma exacerbation, defined as treatment with systemic glucocorticoids or an unscheduled health care consultation for asthma. RESULTS A total of 1922 participants underwent randomization, of whom 1871 were included in the primary analysis. The number of participants who had a severe asthma exacerbation in the year after randomization was 420 (45%) in the quadrupling group as compared with 484 (52%) in the non-quadrupling group, with an adjusted hazard ratio for the time to a first severe exacerbation of 0.81 (95% confidence interval, 0.71 to 0.92; P=0.002). The rate of adverse effects, which were related primarily to local effects of inhaled glucocorticoids, was higher in the quadrupling group than in the non-quadrupling group. CONCLUSIONS In this trial involving adults and adolescents with asthma, a personalized self-management plan that included a temporary quadrupling of the dose of inhaled glucocorticoids when asthma control started to deteriorate resulted in fewer severe asthma exacerbations than a plan in which the dose was not increased. (Funded by the Health Technology Assessment Programme of the National Institute for Health Research; Current Controlled Trials number, ISRCTN15441965.

Chandra Detection of a TypeII Quasar at z=3.288

We report on observations of a TypeII quasar at redshift z=3.288, identified as a hard X-ray source in a 185 ks observation with the Chandra X-ray Observatory and as a high-redshift photometric candidate from deep, multiband optical imaging. CXOJ084837.9+445352 (hereinafter CXO52) shows an unusually hard X-ray spectrum from which we infer an absorbing column density N(H) = (4.8+/-2.1)e23 / cm2 (90% confidence) and an implied unabsorbed 2-10 keV rest-frame luminosity of L(2-10) = 3.3e44 ergs/s, well within the quasar regime. Hubble Space Telescope imaging shows CXO52 to be elongated with slight morphological differences between the WFPC2 F814W and NICMOS F160W bands. Optical and near-infrared spectroscopy of CXO52 show high-ionization emission lines with velocity widths ~1000 km/s and flux ratios similar to a Seyfert2 galaxy or radio galaxy. The latter are the only class of high-redshift TypeII luminous AGN which have been extensively studied to date. Unlike radio galaxies, however, CXO52 is radio quiet, remaining undetected at radio wavelengths to fairly deep limits, f(4.8GHz) < 40 microJy. High-redshift TypeII quasars, expected from unification models of active galaxies and long-thought necessary to explain the X-ray background, are poorly constrained observationally with few such systems known. We discuss recent observations of similar TypeII quasars and detail search techniques for such systems: namely (1) X-ray selection, (2) radio selection, (3) multi-color imaging selection, and (4) narrow-band imaging selection. Such studies are likely to begin identifying luminous, high-redshift TypeII systems in large numbers. We discuss the prospects for these studies and their implications to our understanding of the X-ray background.Comment: 28 pages, 5 figures; to appear in The Astrophysical Journa