408 research outputs found
OPTIMIST: A new conflict resolution algorithm for ACT-R.
Several studies have suggested recently that a more dynamic conflict resolution mechanism in the ACT-R cognitive architecture (Anderson & Lebiere, 1998) could improve the decision-making behaviour of cognitive models. This part of ACT-R theory is revisited and a new solution is proposed. The new algorithm (OPTIMIST) has been implemented as an overlay to the ACT-R architecture, and can be used as an alternative mechanism. The operation of the new algorithm is tested in a model of the classical Yerkes and Dodson experiement of animals' learning. When OPTIMIST is used, the resulting model fits the data better than the previous model (e.g. R2 (R squared) increases from .85 to .93 in one example)
Using spectral diversity and heterogeneity measures to map habitat mosaics: An example from the Classical Karst
Questions: Can we map complex habitat mosaics from remote-Âsensing data? In doing
this, are measures of spectral heterogeneity useful to improve image classification
performance? Which measures are the most important? How can multitemporal data
be integrated in a robust framework?
Location: Classical Karst (NE Italy).
Methods: First, a habitat map was produced from field surveys. Then, a collection of
12 monthly Sentinel-Â2 images was retrieved. Vegetation and spectral heterogeneity
(SH) indices were computed and aggregated in four combinations: (1) monthly layers
of vegetation and SH indices; (2) seasonal layers of vegetation and SH indices; (3)
yearly layers of SH indices computed across the months; and (4) yearly layers of SH
indices computed across the seasons. For each combination, a Random Forest clas-
sification was performed, first with the complete set of input layers and then with a
subset obtained by recursive feature elimination. Training and validation points were
independently extracted from field data.
Results: The maximum overall accuracy (0.72) was achieved by using seasonally ag-
gregated vegetation and SH indices, after the number of vegetation types was re-
duced by aggregation from 26 to 11. The use of SH measures significantly increased
the overall accuracy of the classification. The spectral ÎČ-Âdiversity was the most im-
portant variable in most cases, while the spectral α-Âdiversity and Rao's Q had a low
relative importance, possibly because some habitat patches were small compared to
the window used to compute the indices.
Conclusions: The results are promising and suggest that image classification frame-
works could benefit from the inclusion of SH measures, rarely included before. Habitat
mapping in complex landscapes can thus be improved in a cost-Âand time-Âeffective
way, suitable for monitoring applications
Analysis of health care and actual needs of patients with psoriasis: a survey on the Italian population
Background: Over recent years the public health system has shown increasing interest in patients' views for use as guideline criteria in evaluating the quality of assistance above all for those patients with chronic diseases. Hence the interest in psoriasis, which is a chronic disease frequently associated with diabetes mellitus, hypertension, obesity, and cardiovascular diseases. The aims of our study were to describe clinic characteristics of patients with psoriasis, the quality of the assistance perceived by patients arrived at outpatients clinics and the information received, in order to identify areas in Italy requiring improvement. Methods: 1954 patients, aged between 18 and 85 years, were consecutively enrolled at outpatients clinics across 21 Italian provinces over the period December 2004 - January 2006. A standardized questionnaire was developed in collaboration with an Italian Association of Psoriatic Patients ( A. DI. PSO) and tested in a pilot study. The questionnaire was divided into three sections: the first section included social, demographic and individual variables; the second concerned the quality of the assistance perceived by the patients at public dermatologic clinics and the third focused on the need of information requirements of patients with psoriasis. The chi(2) test was used to estimate the association between the categorical variables under study. Kruskal-Wallis test was applied to the interval and ordinal variables. Results: The presence of psoriatic arthritis was reported in 26.0% of patients. Associated chronic diseases included depression (15.4%), hypertension (13.3%), obesity (8.9%) and type 2 diabetes mellitus (7.3%). The study highlighted the need of improvements of health care services at public dermatologic clinics especially in overcoming architectonic barriers and reducing appointment wait-times, particularly in South Italy. However, patients reported a positive relationship with Health System employers due to the confidentiality. This positive impression was confirmed by the observation that dermatologists were considered the best source of information about therapies on psoriasis. Conclusion: Our study allowed to identify critical aspects which could be tackled through initiatives with the aim of improving these emerged needs
Cost Analysis of Outpatient Anterior Cruciate Ligament Reconstruction: Autograft versus Allograft
Prior studies suggest the cost of allograft anterior cruciate ligament (ACL) reconstruction is less than that for autograft reconstruction. Charges in these studies were influenced by patients requiring inpatient hospitalization.
We therefore determined if allograft ACL reconstruction would still be less costly if all procedures were performed in a completely outpatient setting.
We retrospectively reviewed 155 patients who underwent ACL reconstruction in an ambulatory surgery center between 2001 and 2004; 105 had an autograft and 50 had an allograft. Charges were extracted from itemized billing records, standardized to eliminate cost increases, and categorized for comparison. Surgeon and anesthesiologist fees were not included in the analysis. Groups were compared for age, gender, mean total cost, mean cost of implants, and several other cost categories.
The mean total cost was 4872 for autograft ACL reconstruction. There were no differences in complications between the two groups.
Allograft ACL reconstruction was more costly than autograft ACL reconstruction in the outpatient setting. The cost of the allograft outweighs the increased surgical time needed for harvesting an autograft.
Level II, economic and decision analyses. See Guidelines for Authors for a complete description of levels of evidence
Stem cell therapies for ischemic cardiovascular diseases
Myocardial infarction results in loss of cardiac muscle and deficiency in cardiac performance. Likewise, peripheral artery disease can result in critical limb ischemia leading to reduced mobility, non-healing ulcers, gangrene and amputation. Both of these common conditions diminish quality of life and enhance risk of mortality. Successful advances in treatment have led to more people surviving incidences of myocardial infarction or living with peripheral artery disease. However, the current treatments are inadequate in repairing ischemic tissue. Over the last 5 years, a vast number of patents have been submitted concerning the use of stem cells, which correlates with the exponential growth in stem cell publications. Exploiting stem cell therapy offers a real potential in replacing ischemic tissue with functional cells. In this paper, we review recent patents concerning stem cell therapy that have the potential to provide or potentiate novel treatment for ischemic cardiovascular disease. In addition, we evaluate the promise of the inventions by describing some clinical trials that are currently taking place, as well as considering how current research on ischemic cardiovascular disease may change the patent landscape in the future
ParkDB: a Parkinson's disease gene expression database
Parkinson's disease (PD) is a common, adult-onset, neuro-degenerative disorder characterized by the degeneration of cardinal motor signs mainly due to the loss of dopaminergic neurons in the substantia nigra. To date, researchers still have limited understanding of the key molecular events that provoke neurodegeneration in this disease. Here, we present ParkDB, the first queryable database dedicated to gene expression in PD. ParkDB contains a complete set of re-analyzed, curated and annotated microarray datasets. This resource enables scientists to identify and compare expression signatures involved in PD and dopaminergic neuron differentiation under different biological conditions and across species. Database URL: http://www2.cancer.ucl.ac.uk/Parkinson_Db2
Accuracy of elastic fusion biopsy in daily practice: results of a multicenter study of 2115 patients
OBJECTIVES:
To assess the accuracy of Koelis fusion biopsy for the detection of prostate cancer and clinically significant prostate cancer in the everyday practice.
METHODS:
We retrospectively enrolled 2115 patients from 15 institutions in four European countries undergoing transrectal Koelis fusion biopsy from 2010 to 2017. A variable number of target (usually 2-4) and random cores (usually 10-14) were carried out, depending on the clinical case and institution habits. The overall and clinically significant prostate cancer detection rates were assessed, evaluating the diagnostic role of additional random biopsies. The cancer detection rate was correlated to multiparametric magnetic resonance imaging features and clinical variables.
RESULTS:
The mean number of targeted and random cores taken were 3.9 (standard deviation 2.1) and 10.5 (standard deviation 5.0), respectively. The cancer detection rate of Koelis biopsies was 58% for all cancers and 43% for clinically significant prostate cancer. The performance of additional, random cores improved the cancer detection rate of 13% for all cancers (P < 0.001) and 9% for clinically significant prostate cancer (P < 0.001). Prostate cancer was detected in 31%, 66% and 89% of patients with lesions scored as Prostate Imaging Reporting and Data System 3, 4 and 5, respectively. Clinical stage and Prostate Imaging Reporting and Data System score were predictors of prostate cancer detection in multivariate analyses. Prostate-specific antigen was associated with prostate cancer detection only for clinically significant prostate cancer.
CONCLUSIONS:
Koelis fusion biopsy offers a good cancer detection rate, which is increased in patients with a high Prostate Imaging Reporting and Data System score and clinical stage. The performance of additional, random cores seems unavoidable for correct sampling. In our experience, the Prostate Imaging Reporting and Data System score and clinical stage are predictors of prostate cancer and clinically significant prostate cancer detection; prostate-specific antigen is associated only with clinically significant prostate cancer detection, and a higher number of biopsy cores are not associated with a higher cancer detection rate
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Analysis of liquid-solids suspension velocities and concentrations obtained by NMR imaging
COMMIX-M, a three-dimensional transient and steady-state computer program written in Cartesian and cylindrical coordinates, has been developed by Argonne National Laboratory. This computer program is capable of analyzing multiphase flow and heat transfer and utilizes the separate phases model wherein each phase has its own mass, momentum, and energy equations. This computer program is in its early stages of development for application to test various interphase interaction models and to predict design and processing of dense fluid-solids suspension systems. COMMIX-M contains preliminary constitutive relationships for interfacial drag, solids viscosities and stresses to describe the solids rheology, and shear lift forces from the literature. Also included is a solids partial slip boundary condition to allow non-zero tangential velocity at the tube walls. Analyses of some of the steady-state, fully-developed isothermal carrier fluid velocity and solids concentration data of Altobelli et al. and Sinton and Chow are presented. These experimental data obtained using three-dimensional time-of-flight nuclear magnetic (NMR) imaging techniques were carefully performed and represent some of the best available open literature data of their kind. NMR imaging offers powerful techniques to non-intrusively determine three-dimensional time-dependent velocity and concentration fields to assist development and validation of the constitutive models and the computer programs describing concentrated suspensions. Analyses of these NMR data, together with comparisons of computed and measured concentration and velocity profiles provide some insights into the mechanisms governing the observed phenomena. Recommendations for future research are given. To the authors` knowledge, these are the first such comparisons of theory and experiment
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