Synchronized Oscillations During Cooperative Feature Linking in a Cortical Model of Visual Perception

A neural network model of synchronized oscillator activity in visual cortex is presented in order to account for recent neurophysiological findings that such synchronization may reflect global properties of the stimulus. In these recent experiments, it was reported that synchronization of oscillatory firing responses to moving bar stimuli occurred not only for nearby neurons, but also occurred between neurons separated by several cortical columns (several mm of cortex) when these neurons shared some receptive field preferences specific to the stimuli. These results were obtained not only for single bar stimuli but also across two disconnected, but colinear, bars moving in the same direction. Our model and computer simulations obtain these synchrony results across both single and double bar stimuli. For the double bar case, synchronous oscillations are induced in the region between the bars, but no oscillations are induced in the regions beyond the stimuli. These results were achieved with cellular units that exhibit limit cycle oscillations for a robust range of input values, but which approach an equilibrium state when undriven. Single and double bar synchronization of these oscillators was achieved by different, but formally related, models of preattentive visual boundary segmentation and attentive visual object recognition, as well as nearest-neighbor and randomly coupled models. In preattentive visual segmentation, synchronous oscillations may reflect the binding of local feature detectors into a globally coherent grouping. In object recognition, synchronous oscillations may occur during an attentive resonant state that triggers new learning. These modelling results support earlier theoretical predictions of synchronous visual cortical oscillations and demonstrate the robustness of the mechanisms capable of generating synchrony.

Processing of Synthetic Aperture Radar Images by the Boundary Contour System and Feature Contour System

An improved Boundary Contour System (BCS) and Feature Contour System (FCS) neural network model of preattentive vision is applied to two large images containing range data gathered by a synthetic aperture radar (SAR) sensor. The goal of processing is to make structures such as motor vehicles, roads, or buildings more salient and more interpretable to human observers than they are in the original imagery. Early processing by shunting center-surround networks compresses signal dynamic range and performs local contrast enhancement. Subsequent processing by filters sensitive to oriented contrast, including short-range competition and long-range cooperation, segments the image into regions. Finally, a diffusive filling-in operation within the segmented regions produces coherent visible structures. The combination of BCS and FCS helps to locate and enhance structure over regions of many pixels, without the resulting blur characteristic of approaches based on low spatial frequency filtering alone.

Cortical Dynamics of Feature Binding and Reset: Control of Visual Persistence

An analysis of the reset of visual cortical circuits responsible for the binding or segmentation of visual features into coherent visual forms yields a model that explains properties of visual persistence. The reset mechanisms prevent massive smearing or visual percepts in response to rapidly moving images. The model simulates relationships among psychophysical data showing inverse relations of persistence to flash luminance and duration, greaterr persistence of illusory contours than real contours, a U-shaped temporal function for persistence of illusory contours, a reduction of persistence: due to adaptation with a stimulus of like orientation, an increase or persistence due to adaptation with a stimulus of perpendicular orientation, and an increase of persistence with spatial separation of a masking stimulus. The model suggests that a combination of habituative, opponent, and endstopping mechanisms prevent smearing and limit persistence. Earlier work with the model has analyzed data about boundary formation, texture segregation, shape-from-shading, and figure-ground separation. Thus, several types of data support each model mechanism and new predictions are made.

A medical study on wireless inertial measurement technology as a tool for identifying patients at risk of death or imminent clinical deterioration

This paper provides a system description and preliminary results for an ongoing clinical study currently being carried out at the Mid-Western Regional Hospital, Nenagh, Ireland. The goal of the trial is to determine if wireless inertial measurement technology can be employed to identify elderly patients at risk of death or imminent clinical deterioration. The system measures cumulative movement and provides a score that will help provide a robust early warning to clinical staff of clinical deterioration. In addition the study examines some of the logistical barriers to the adoption of wearable wireless technology in front-line medical care.

Hospital clinicians information behaviour and attitudes towards the 'Clinical Informationist': an Irish survey

Background: Hospital clinicians are increasingly expected to practice evidence-based medicine (EBM) in order to minimize medical errors and ensure quality patient care, but experience obstacles to information-seeking. The introduction of a Clinical Informationist (CI) is explored as a possible solution. Aims:  This paper investigates the self-perceived information needs, behaviour and skill levels of clinicians in two Irish public hospitals. It also explores clinicians perceptions and attitudes to the introduction of a CI into their clinical teams. Methods: A questionnaire survey approach was utilised for this study, with 22 clinicians in two hospitals. Data analysis was conducted using descriptive statistics. Results: Analysis showed that clinicians experience diverse information needs for patient care, and that barriers such as time constraints and insufficient access to resources hinder their information-seeking. Findings also showed that clinicians struggle to fit information-seeking into their working day, regularly seeking to answer patient-related queries outside of working hours. Attitudes towards the concept of a CI were predominantly positive. Conclusion: This paper highlights the factors that characterise and limit hospital clinicians information-seeking, and suggests the CI as a potentially useful addition to the clinical team, to help them to resolve their information needs for patient care.

The use of atraumatic restorative treatment in elderly patients: a randomised controlled clinical trial

Objectives: to assess elderly patients’ dental status and dental habits and compare the survival rates, impact on patients’ quality of life and cost-effectiveness of Atraumatic Restorative Treatment (ART) and a conventional treatment (CT) to restore carious lesions in an elderly population. Methods: In this randomised clinical trial, 99 independently living adults (65-90 yrs) with carious lesions were randomly allocated to receive either ART or CT. Details of restored, missing and carious teeth were recorded and patients answered some questions about their oral hygiene and dental attendance habits. Direct and indirect costs were measured based on treatment time, materials and labour. Effectiveness was measured using restoration survival percentage after one year. The survival of restorations was assessed 6 months and one year after restoration placement by an independent examiner. Oralhealth related quality of life (OHRQoL) was assessed using the OHIP-14 at baseline and 2 months after treatment together with a global transition statement. Results: The patient sample comprised 46 (46.46%) male and 53 (53.54) female participants at baseline, with a mean age of 73.18 (SD=6.76). The mean DMFT of the entire sample was 27.10. Ninety patients and 268 restorations could be assessed after one year, 127 ART (46 patients) and 141 conventional restorations (44 patients). 93.7% and 97.2% of the restorations placed were considered successful in the ART and CT groups, respectively. The OHIP scores did not change dramatically 2 months after treatment, in either group. The global transition scale showed an improvement in overall oral health after treatment for the majority of patients. The ART were more cost-effective compared to the CT restorations. Conclusions: ART presented survival rates similar to CT after 1 year and was a more cost-effective alternative to treat the elderly.

Genetic analysis of bacteriophages from clinical and environmental samples

Bacteriophages, viruses infecting bacteria, are uniformly present in any location where there are high numbers of bacteria, both in the external environment and the human body. Knowledge of their diversity is limited by the difficulty to culture the host species and by the lack of the universal marker gene present in all viruses. Metagenomics is a powerful tool that can be used to analyse viral communities in their natural environments. The aim of this study was to investigate diverse populations of uncultured viruses from clinical (a sputum of patient with cystic fibrosis, CF) and environmental samples (a sludge from a dairy food wastewater treatment plant) containing rich bacterial populations using genetic and metagenomic analyses. Metagenomic sequencing of viruses obtained from these samples revealed that the majority of the metagenomic reads (97-99%) were novel when compared to the NCBI protein database using BLAST. A large proportion of assembled contigs were assignable as novel phages or uncharacterised prophages, the next largest assignable group being single-stranded eukaryotic virus genomes. Sputum from a cystic fibrosis patient contained DNA typical of phages of bacteria that are traditionally involved in CF lung infections and other bacteria that are part of the normal oral flora. The only eukaryotic virus detected in the CF sputum was Torque Teno virus (TTV). A substantial number of assigned sequences from dairy wastewater could be affiliated with phages of bacteria that are typically found in the soil and aquatic environments, including wastewater. Eukaryotic viral sequences were dominated by plant pathogens from the Geminiviridae and Nanoviridae families, and animal pathogens from the Circoviridae family. Antibiotic resistance genes were detected in both metagenomes suggesting phages could be a source for transmissible antimicrobial resistance. Overall, diversity of viruses in the CF sputum was low, with 89 distinct viral genotypes predicted, and higher (409 genotypes) in the wastewater. Function-based screening of a metagenomic library constructed from DNA extracted from dairy food wastewater viruses revealed candidate promoter sequences that have ability to drive expression of GFP in a promoter-trap vector in Escherichia coli. The majority of the cloned DNA sequences selected by the assay were related to ssDNA circular eukaryotic viruses and phages which formed a minority of the metagenome assembly, and many lacked any significant homology to known database sequences. Natural diversity of bacteriophages in wastewater samples was also examined by PCR amplification of the major capsid protein sequences, conserved within T4-type bacteriophages from Myoviridae family. Phylogenetic analysis of capsid sequences revealed that dairy wastewater contained mainly diverse and uncharacterized phages, while some showed a high level of similarity with phages from geographically distant environments.

Clinical autonomy and nurse/physician collaboration in emergency nurses

Aim: To investigate clinical autonomy and Nurse/Physician collaboration among emergency nurses and the relationship between these concepts, personal characteristics and organisational influences. Background: Nurses have been identified as having a significant role in addressing the challenges of providing modern healthcare. Emergency nurses have reported competence in a wide range of emergency care skills. However, there is evidence that Emergency Department (ED) nurses may have lower levels of clinical autonomy than other areas of practice. Levels of clinical autonomy appear to be influenced by levels of collaboration with physicians and the organisations in which nurses work Methods: A descriptive correlational study using a survey design with a purposive convenience sample of 141 ED staff nurses (response 70.9%) from 3 EDs in Ireland. Data were collected using the Dempster Practice Behaviours Scale (DPBS) the Nurse/Physician Collaboration Scale (NPCS) and the newly developed Organisational Influences on Nursing Scale. Demographic information was also sought from participants. Results: Participants were largely female (87%), relatively young (mean age 35.57, SD=7.83) and educated to degree level (48%) or higher (31%) with 40% posessing specialist emergency nursing qualifications. Participants reported moderate levels of clinical autonomy and Nurse/Physician collaboration. No relationships were found between sample characteristics and clinical autonomy and Nurse/Physician collaboration among emergency nurses. Relationships were found between levels of clinical autonomy and Nurse/Physician collaboration (r=-0.395, n=100, p<0.001), and organisational influence on nursing (r=0.455, p<0.001) and also between Nurse/Physician collaboration and organisational influence on nursing (r=-0.413, p<0.001). Discussion: Clinical autonomy of nurses has been linked with quality outcomes in healthcare. The quest for quality in modern healthcare in a challenging environment should acknowledge that strategies need to focus beyond education and skills provision and include essential elements such as Nurse/Physician collaboration and the organisational influence on nursing to ensure the greater involvement of nurses in patient care.