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Simple Features (simple + feature)

Distribution by Scientific Domains

Life Sciences	50%

Selected Abstracts

Can we predict future improvement in glycaemic control?

DIABETIC MEDICINE, Issue 2 2008
R. Singh
Abstract Aims To determine the factors responsible for poor glycaemic control in diabetes and whether any such factors are associated with likely improvement in glycaemic control. Methods A prospective cohort study of 130 diabetic patients with poor glycaemic control (HbA1c , 10.0%) with 1-year follow-up in a teaching hospital Diabetes Clinic. Changes in HbA1c were measured after 1 year. Results Poor glycaemic control was attributed to one of 15 possible causes. Those cases due to recent diagnosis of diabetes, inadequate treatment with diet, oral glucose-lowering agents or insulin, exacerbation of co-existent medical problems, recent stressful life-events and missed clinic appointments were all associated with significant improvement in HbA1c at 12 months. Patients with low mood or alcohol excess, inadequate blood glucose monitoring, poor exercise/sedentary lifestyle, refusal to take tablets or underdosing and refusal to take insulin at all or to increase the dose were all associated with continuing poor glycaemic control at 12 months. The patients were divided almost equally between the two groups. Conclusions In patients with poor glycaemic control, it is possible by simple features identified at clinic to predict which individuals are likely to show improvement in control and which will not. These findings have not been reported previously and suggest that about half of individuals with poor control will improve within our current diabetes clinic practice. Additional strategies will be required to address those individuals who are not likely to respond. [source]

The organization of visual object representations: a connectionist model of effects of lesions in perirhinal cortex

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2002
Timothy J. Bussey
Abstract We have developed a simple connectionist model based on the idea that perirhinal cortex has properties similar to other regions in the ventral visual stream, or ,what' pathway. The model is based on the assumption that representations in the ventral visual stream are organized hierarchically, such that representations of simple features of objects are stored in caudal regions of the ventral visual stream, and representations of the conjunctions of these features are stored in more rostral regions. We propose that a function of these feature conjunction representations is to help to resolve ,feature ambiguity', a property of visual discrimination problems that can emerge when features of an object predict a given outcome (e.g. reward) when part of one object, but predict a different outcome when part of another object. Several recently reported effects of lesions of perirhinal cortex in monkeys have provided key insights into the functions of this region. In the present study these effects were simulated by comparing the performance of connectionist networks before and after removal of a layer of units corresponding to perirhinal cortex. The results of these simulations suggest that effects of lesions in perirhinal cortex on visual discrimination may be due not to the impairment of a specific type of learning or memory, such as declarative or procedural, but to compromising the representations of visual stimuli. Furthermore, we propose that attempting to classify perirhinal cortex function as either ,perceptual' or ,mnemonic' may be misguided, as it seems unlikely that these broad constructs will map neatly onto anatomically defined regions of the brain. [source]

Vision-only control and guidance for aircraft

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 10 2006
Alison A. Proctor
An unmanned aerial vehicle usually carries an array of sensors whose output is used to estimate vehicle attitude, velocity, and position. This paper details the development of guidance, navigation, and control strategies for a glider, which is capable of flying a terminal trajectory to a known fixed object using only a single vision sensor. Controlling an aircraft using only vision presents two unique challenges: First, absolute state measurements are not available from a single image; and second, the images must be collected and processed at a high rate to achieve the desired controller performance. The image processor utilizes an integral image representation and a rejective cascade filter to find and classify simple features in the images, reducing the image to the most probable pixel location of the destination object. Then, an extended Kalman filter uses measurements obtained from a single image to estimate the states that would otherwise be unobservable in a single image. In this research, the flights are constrained to keep the destination object in view. The approach is validated through simulation. Finally, experimental data from autonomous flights of a glider, instrumented only with a single nose-mounted camera, intercepting a target window during short low-level flights, are presented. © 2006 Wiley Periodicals, Inc. [source]

An unexpectedly sophisticated, V-shaped spermatozoon in Demospongiae (Porifera): reproductive and evolutionary implications

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 2 2009
ANA RIESGO
The demosponge Crambe crambe shows a peculiar spermatogenesis, hard to be reconciled with the basal position of sponges in the animal phylogeny. Early spermatogenesis stages showed most of the simple features expected in sponges. However, spermiogenesis departed from the anticipated process. Spermatids lengthened remarkably, forming a deep cytoplasmic pit around the cilium insertion, with the proximal axoneme bending to produce a V-shaped spermatozoon surprisingly similar to that known in the phylum Phoronida. The cytology was unexpectedly complex, with a needle-like nucleus of helically condensed chromatin, a conical acrosome with a subacrosomal rod, and a mitochondrion connected to the basal body by striated rootlets. These findings establish that the spermatozoon of broad-casting demosponges occurs in two structural categories (,primitive' and ,modified' type). This dualistic condition must necessarily have pre-dated the evolutionary apparition of higher metazoans, if we are to keep regarding sponges as the most primitive animals. We hypothesize that internal fertilization in C. crambe, and incidentally other demosponges , may depart from the general model assumed for spermcasting sponges. The V-shape of this spermatozoon suggests a design to favour autonomous penetration through the dense mesohyl to reach the oocytes, rather than engulfment and transportation by carrier cells towards the oocyte. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 413,426. [source]