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Selected AbstractsIdentification of a class of non-linear parametrically varying modelsINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 1 2003F. Previdi The aim of this paper is to propose a novel class of non-linear, possibly parameter-varying models suitable for system identification purposes. These models are given in the form of a linear fractional transformation (LFT) where the ,forward' part is represented by a conventional linear regression and the ,feedback' part is given by a non-linear dynamic map parameterized by a neural network (NN) which can take into account scheduling variables available for measurement. For this specific model structure a parameter estimation procedure has been set up, which turns out to be particularly efficient from the computational point of view. Also, it is possible to establish a connection between this model class and the well known class of local model networks (LMNs): this aspect is investigated in the paper. Finally, we have applied the proposed identification procedure to the problem of determining accurate non-linear models for knee joint dynamics in paraplegic patients, within the framework of a functional electrical stimulation (FES) rehabilitation engineering project. Copyright © 2002 John Wiley & Sons, Ltd. [source] Modeling distributions of disjunct populations of the Sierra Madre SparrowJOURNAL OF FIELD ORNITHOLOGY, Issue 3 2008Octavio R. Rojas-Soto ABSTRACT Sierra Madre Sparrows (Xenospiza baileyi) are among the least known of all bird species in Mexico. Recent surveys have discovered previously unknown populations and the current known distribution of Sierra Madre Sparrows consists of two populations separated by >800 km. We used available distributional information to develop ecological niche models that (1) predict much of the distribution potential of the species, (2) establish that the broad disjunction separating the two populations has ecological correlates that appear to be important to the distributional of these sparrows, and (3) illustrate the extremely restricted ecological distribution of the species. We used two sets of climatic and topographic variables, with one including all 22 variables available and the second with only six variables that were positively related to quality of distributional models. Although indications of differences between the two sets of populations were found based on the full 22-dimensional environmental dataset, such a highly dimensional analysis is vulnerable to over-fitting; models based on the reduced dataset indicated that the two populations occur in areas with similar ecological conditions. Our models also suggest that southern population of Sierra Madre Sparrows covers most of their potential range in that region. The potential range of the northern population, however, extends beyond known points of occurrence. To clarify the distribution of Sierra Madre Sparrows and evaluate their status and conservation opportunities, detailed searches for additional populations in areas identified by the model are needed. SINOPSIS El gorrión serrano (Xenospiza baileyi) se encuentra entre las especies menos conocidas de México. En un estudio reciente se descubrieron nuevas poblaciones, por lo que la distribución actual de esta ave está conformada por dos meta-poblaciones separadas por más de 800 km. Utilizamos la información disponible sobre su distribución para desarrollar modelos del nicho ecológico que: 1) predigan la mayor parte de la distribución potencial de la especie, 2) establezcan que la amplia separación de las dos poblaciones está correlacionada con condiciones ecológicas que parecen ser importantes para la distribución de la especie y 3) ilustren la extrema restricción ecológica que caracteriza la distribución de la especie. Para generar los modelos, utilizamos dos conjuntos de variables climatológicas y topográficas. Uno con 22 variables y el otro con las seis variables que estaban positivamente correlacionadas con la calidad de los modelos de distribución. Aunque se encontraron indicios de diferencias ecológicas entre las dos poblaciones con base en las 22 variables ambientales estudiadas, el análisis con tantas dimensiones es sensible a un efecto de sobre-ajuste. Los modelos producidos con el subconjunto de seis variables indicaron que las dos poblaciones se encuentran en áreas con condiciones ecológicas similares. Nuestros modelos sugieres que la población del sur ocupa la mayor parte de su área de distribución potencial en la región. No obstante, la distribución potencial de la población del norte es mucho más amplia que su distribución conocida. Es necesario realizar búsquedas minuciosas del gorrión serrano en los sitios identificados por el modelo propuesto para definir adecuadamente su distribución, evaluar su estatus y buscar oportunidades para su conservación. [source] Nowcasting quarterly GDP growth in a monthly coincident indicator modelJOURNAL OF FORECASTING, Issue 8 2005Luis C. NunesArticle first published online: 20 DEC 200 Abstract This paper presents an extension of the Stock and Watson coincident indicator model that allows one to include variables available at different frequencies while taking care of missing observations at any time period. The proposed procedure provides estimates of the unobserved common coincident component, of the unobserved monthly series underlying any included quarterly indicator, and of any missing values in the series. An application to a coincident indicator model for the Portuguese economy is presented. We use monthly indicators from business surveys whose results are published with a very short delay. By using the available data for the monthly indicators and for quarterly real GDP, it becomes possible to produce simultaneously a monthly composite index of coincident indicators and an estimate of the latest quarter real GDP growth well ahead of the release of the first official figures. Copyright © 2005 John Wiley & Son, Ltd. [source] Development and Validation of a Risk Scoring Model to Predict Net Adverse Cardiovascular Outcomes after Primary Percutaneous Coronary Intervention in Patients Pretreated with 600 mg Clopidogrel: Rationale and Design of the RISK-PCI StudyJOURNAL OF INTERVENTIONAL CARDIOLOGY, Issue 4 2009IGOR MRDOVIC M.D., Ph.D Background: No comprehensive primary PCI (pPCI) risk model to predict net adverse cardiovascular events (NACE) has been reported with the use of clopidogrel 600 mg, which is now considered the standard loading dose. The primary hypothesis of the RISK-PCI trial is that an accurate risk prediction may be achieved by using clinical, angiographic, and procedural variables available at the time of intervention. Methods: The present single-center, longitudinal, cohort study will include 1,750 consecutive patients with ST-elevation myocardial infarction (STEMI), undergoing pPCI after pretreatment with 300 mg aspirin and 600 mg clopidogrel. The primary end-points of the trial (NACE) include major adverse cardiovascular events (MACE) and major bleeding. A logistic regression model will be developed to predict 30-day and 1-year NACE after pPCI. A risk score derived from study set data will be validated using validation set data. Results: Until June 1, 2008, 1,166 patients have been enrolled. Thirty-day follow-up is available in 1,007 patients. Conclusions: The RISK-PCI study is designed to develop an accurate risk scoring system, using variables available at the time of intervention, to predict long-term adverse outcomes after pPCI. Trial Registration: Current Controlled Trials Register,ISRCTN83474650,http://www.controlled-trials.com/ISRCTN83474650). [source] Laboratory and clinical outcomes of pharmacogenetic vs. clinical protocols for warfarin initiation in orthopedic patientsJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 10 2008P. A. LENZINI Summary.,Background:,Warfarin is commonly prescribed for prophylaxis and treatment of thromboembolism after orthopedic surgery. During warfarin initiation, out-of-range International Normalized Ratio (INR) values and adverse events are common. Methods:,In orthopedic patients beginning warfarin therapy, we developed and prospectively validated pharmacogenetic and clinical dose refinement algorithms to revise the estimated therapeutic dose after 4 days of therapy. Results:,The pharmacogenetic algorithm used the cytochrome P450 (CYP) 2C9 genotype, smoking status, peri-operative blood loss, liver disease, INR values and dose history to predict the therapeutic dose. The R2 was 82% in a derivation cohort (n = 86) and 70% when used prospectively (n = 146). The R2 of the clinical algorithm that used INR values and dose history to predict the therapeutic dose was 57% in a derivation cohort (n = 178) and 48% in a prospective validation cohort (n = 146). In 1 month of prospective follow-up, the percent time spent in the therapeutic range was 7% higher (95% CI: 2.7,11.7) in the pharmacogenetic cohort. The risk of a laboratory or clinical adverse event was also significantly reduced in the pharmacogenetic cohort (Hazard Ratio 0.54; 95% CI: 0.30,0.97). Conclusions:,Warfarin dose adjustments that incorporate genotype and clinical variables available after four warfarin doses are accurate. In this non-randomized, prospective study, pharmacogenetic dose refinements were associated with more time spent in the therapeutic range and fewer laboratory or clinical adverse events. To facilitate gene-guided warfarin dosing we created a non-profit website, http://www.WarfarinDosing.org. [source] A comparative study of a 595-nm with a 585-nm pulsed dye laser in refractory port wine stainsBRITISH JOURNAL OF DERMATOLOGY, Issue 3 2005A. Yung Summary Background, The pulsed dye laser (PDL) is the treatment of choice for port wine stains (PWS); however, some patients' PWS become refractory to further treatments. Technological advances have enabled new machines with the advent of surface cooling devices to deliver longer wavelengths and higher fluence more safely. These advances have the potential to achieve improved response rates in refractory PWS. There are few studies comparing the efficacy of standard PDL treatments for refractory PWS with the wider choice of treatment variables available from newer PDL machines. Objectives, To determine if there is any advantage of using a longer wavelength (595 nm) and pulse widths (1·5 ms, 6 ms and 20 ms) over conventional PDL settings (wavelength 585 nm, pulse width 1·5 ms) in refractory PWS. Methods, Eighteen consecutive consenting patients with Fitzpatrick skin types 1,4 with a mean age 35 years (range 17,59 years) with refractory PWS were treated routinely with three separate test areas using 595-nm PDL (using three different pulse width settings of 1·5 ms, 6 ms and 20 ms), compared with test areas treated with 585-nm PDL (pulse width 1·5 ms). All test areas were treated with an identical fluence (15 J cm,2), spot size (7 mm) and cooling setting (dynamic cooling 60 ms, delay 60 ms). Results, We found a statistically significant advantage of 595-nm PDL (pulse width 1·5 ms) over 595-nm PDL (pulse width 6 ms) (P < 0·05) in the treatment of refractory PWS; however, we found no significant advantage using longer pulse widths of 20 ms compared with 1·5 ms with the 595-nm PDL. There was no statistically significant advantage in using a 595-nm PDL over a 585-nm PDL using identical pulse widths of 1·5 ms, spot size, fluence and cryogen cooling settings; however, the number of directly comparable test areas was smaller. Some individual patients in our study obtained a better response with certain 595-nm PDL settings (pulse width 1·5 ms and 6 ms) compared with 585-nm PDL (pulse width 1·5 ms). Conclusions, Our experience of high fluence PDL in the treatment of refractory PWS suggests patients treated with 585 nm (pulse width 1·5 ms) improve to a similar degree as patients treated with 595-nm PDL (pulse width 1·5 ms). However, the use of the 595-nm PDL with longer pulse widths yields no extra advantage. For those patients who have failed to improve with high-fluence 585-nm PDL (pulse width 1·5 ms), test areas using 595-nm PDL (pulse width 1·5 ms and 6 ms) should be undertaken to ascertain if individual patients may benefit from the longer pulse width 595-nm PDL. 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