A silviculture-oriented spatio-temporal model for germination in Pinus pinea L. in the Spanish Northern Plateau based on a direct seeding experiment

Natural regeneration in Pinus pinea stands commonly fails throughout the Spanish Northern Plateau under current intensive regeneration treatments. As a result, extensive direct seeding is commonly conducted to guarantee regeneration occurrence. In a period of rationalization of the resources devoted to forest management, this kind of techniques may become unaffordable. Given that the climatic and stand factors driving germination remain unknown, tools are required to understand the process and temper the use of direct seeding. In this study, the spatio-temporal pattern of germination of P. pinea was modelled with those purposes. The resulting findings will allow us to (1) determine the main ecological variables involved in germination in the species and (2) infer adequate silvicultural alternatives. The modelling approach focuses on covariates which are readily available to forest managers. A two-step nonlinear mixed model was fitted to predict germination occurrence and abundance in P. pinea under varying climatic, environmental and stand conditions, based on a germination data set covering a 5-year period. The results obtained reveal that the process is primarily driven by climate variables. Favourable conditions for germination commonly occur in fall although the optimum window is often narrow and may not occur at all in some years. At spatial level, it would appear that germination is facilitated by high stand densities, suggesting that current felling intensity should be reduced. In accordance with other studies on P. pinea dispersal, it seems that denser stands during the regeneration period will reduce the present dependence on direct seeding

Evaluating the approach run of class F11 visually impaired athletes in triple and long jumps

The present study examined stride pattern characteristics of Class F11 visually impaired long jumpers and triple jumpers. Athletes demonstrated initial ascending footfall variability followed by descending variability, on the second (long jumpers) and third (triple jumpers) stride prior to take-off, at a mean distance of 6.26 m (long jumpers) and 7.36 m (triple jumpers) from the take-off board. Toeboard- distance variability reached a maximum value of 0.36 m and 0.38 m for the long and triple jump, respectively. Last stride toe-board-distance variability was 0.29 m (long jump) and 0.25 m (triple jump). Class F11 visually impaired athletes exhibit regulation of goal-directed gait analogous to that of non-visually impaired athletes. © Perceptual and Motor Skills 2012

An 18-item standardized Asthma Quality of Life Questionnaire-AQLQ(S)

The purpose of the present study was to examine the validity and reliability of the Asthma Quality of Life Questionnaire-AQLQ(S) in a sample of 160 Greek patients with asthma. Following evidence for sample-specific validity, the AQLQ(S) model was examined through exploratory and confirmatory factor analysis. An 18-item AQLQ(S) with the four factors of symptoms, activity limitations, sleep, and exposure in environmental stimuli fits the data (χ2/df ratio = 2.26, NNFI = 0.92, CFI = 0.94, SRMR = 0.05). The 18-item AQLQ(S) showed a high internal consistency (Cronbach' a coefficient ranged from 0.83 to 0.96) and high 9-week test-retest reliability (overall r = 0.88, ICC = 0.94). Responsiveness was confirmed throughout 2X2 ANOVA and 2X2 MANOVA, with respect to the total score (F = 42.30, P < 0.05), and the four AQLQ(S) factors (Wilks' λ = 0.68, F = 17.59, P < 0.05). The cross-sectional correlations between the 18-item AQLQ(S) and the: (1) FEV1% predicted and (2) Borg scale were low and moderately high, respectively. In conclusion, the 18-item AQLQ(S) derived from exploratory and confirmatory factor analysis appeared to have sufficient construct validity, cross-sectional validity, responsiveness, satisfactory test-retest reliability and internal consistency evidence for the Greek sample of adults with asthma. © 2007 Springer Science+Business Media B.V

Kinesthetic ability in children with spastic hemiplegia

The purpose was to examine the differences in kinesthetic ability, at the elbow joint, between children with (n = 15) and without (n= 15) spastic hemiplegia. The Kin Com 125 AP isokinetic dynamometer Configuration Chattanooga was used. Results revealed significant (p < .05) interaction between participant groups and side which was a repeated measures factor (nonaffected side for CP group and dominant side for nonCP group vs. affected side for CP and nondominant side for nonCP group) with respect to the passive reproduction of movement (PRM) and detection of passive movement (DPM). The interaction was attributed to the kinesthetic deficits of the hemiplegic participants compared to the control group. A significant relationship was found between the level of spasticity and PRM scores. © 2007 Human Kinetics, Inc

Source localization and multichannel speech enhancement

76 σ.Η παρούσα διπλωματική εργασία έχει ως αντικείμενο τον εντοπισμό θέσης πηγής ακουστικού σήματος και την αποθορυβοποίηση ομιλίας με πολυκαναλική επεξεργασία. Για το πρόβλημα του εντοπισμού θέσης πηγής, προτείνεται μία νέα μέθοδος ελαχίστων τετραγώνων για τη βέλτιστη εκτίμηση της θέσης πηγής από τις κατευθύνσεις άφιξης (Direction of Arrival, DOA) του σήματος πηγής σε ζεύγη μικροφώνων. Η κατεύθυνση άφιξης υπολογίζεται εκτιμώντας τη διαφορά χρόνου άφιξης (Time Difference of Arrival, TDOA) του σήματος πηγής στο εκάστοτε ζεύγος μικροφώνων. Για την εκτίμηση TDOA χρησιμοποιείται η μέθοδος μετρικού συνοχής φασης ετεροφάσματος (Crosspower-spectrum Phase Coherence Measure, CSP-CM) με βελτιώσεις στην ακρίβεια και την υπολογιστική πολυπλοκότητά της. Η προτεινόμενη μέθοδος εντοπισμού θέσης με ελάχιστα τετράγωνα καταλήγει σε εκτίμηση κλειστής μορφής για τη θέση της πηγής, συνεπώς είναι υπολογιστικά αποδοτική και κατάλληλη για εφαρμογές πραγματικού χρόνου. Για το πρόβλημα της πολυκαναλικής αποθορυβοποίησης σημάτων, γίνεται μελέτη της επίδρασης της γεωμετρίας της συστοιχίας μικροφώνων στην αποτελεσματικότητα πολυκαναλικού συστήματος αποθορυβοποίησης με MVDR beamforming και post-filtering. Για το σκοπό αυτό, έγινε συλλογή βάσης δεδομένων με πολυκαναλικές ηχογραφήσεις σε πραγματικές συνθήκες για εξαγωνικές και γραμμικές διατάξεις της συστοιχίας μικροφώνων σε διάχυτο (diffuse) και εντοπισμένο (localized) θόρυβο. Για τη συλλογή της βάσης, χρησιμοποιήθηκε συστοιχία με μικρόφωνα MEMS, τα οποία είναι μία νέα τεχνολογία φορητών μικροφώνων πολύ μικρών διαστάσεων. Πέραν της πειραματικής αυτής μελέτης, προτείνεται μία θεωρητική βελτίωση στη μέθοδο εκτίμησης των παραμέτρων του post-filter για το χρησιμοποιηθέν σύστημα πολυκαναλικής αποθορυβοποίησης, όμως αποδεικνύεται ότι στην πράξη αυτή δε βελτιώνει την έξοδο του post-filter.This thesis focuses on the problems of source localization and speech enhancement through multichannel signal processing. For the source localization problem, a novel least-squares (LS) method for estimating the source location from the Direction of Arrival (DOA) of the source signal to microphone pairs is proposed. To calculate the DOA, the Time Difference of Arrival (TDOA) of the source signal to the respective microphone pair is first estimated. The TDOA estimation is carried out using the Crosspower-Spectrum Phase Coherence Measure (CSP-CM) with some improvements to its computational efficiency and its accuracy. The proposed LS source localization method yields a closed-form source location estimator and is therefore efficient and suitable for real-time applications. For the multichannel speech enhancement problem, the effect of the microphone array geometry on the efficacy of a multichannel speech enhancement system with MVDR beamforming and post-filtering is studied. To this end, a multichannel database was formed by collecting real recorded data for hexagonal and linear arrangements of the microphone array in diffuse and localized noise fields. For the data collection, a microphone array consisting of MEMS (MicroElectroMechanical Systems) microphones, which are a newly developed technology of highly compact sensors, was used. Besides this experimental study, a theoretical improvement on the post-filter parameter estimation method of the multichannel speech enhancement system employed is proposed, however it is shown that in practice this does not improve the post-filter output.Ζήσης-Ιάσων Ε. Σκορδίλη