During the early stages of infant development the capacity for perceptual (i.e., visual) discrimination is shaped by infants' perceptual experience. Perceptual narrowing is one process hypothesized to account for developmental change. Perceptual narrowing research often demonstrates that infants before 6 months of age are able to discriminate a wide variety of events whereas infants beyond 6 months of age seemingly "lose" some perceptual abilities. Two investigations are proposed to examine the claim that younger, but not older infants can discriminate faces across species. The purpose of Experiment 1 was to determine whether an increase in familiarization and trial times would result in cross-species facial (i.e. faces of macaques) discrimination in 12-month-olds. The hypothesis was supported, adding evidence that perceptual discrimination becomes more constricted, or less efficient with age, but does not decline. Experiment 2 examined whether reducing both the time of familiarization and comparison time by 50% would allow infants sufficient time to discriminate. Results were consistent with the hypothesis and previous studies were corroborated. These findings highlight the important role of perceptual experience in young infants' perceptual discrimination abilities and provide a greater degree of clarity regarding present use of the concept perceptual narrowing.

No description available.

The theory of perceptual narrowing posits that the ability to make perceptual discriminations is very broad early in development and subsequently becomes more specific with perceptual experience (Scott, Pascalis, & Nelson, 2007). This leads to the formation of biases (Pascalis et al., 2002; 2005; Kelly et al., 2007), including the other-race effect (ORE). Behavioral and electrophysiological measures are used to show that by 9-months-of-age, infants exhibit a decline in ability to distinguish between two faces from another race compared to two faces from within their own race. Significant differences in the P400 component revealed a dampening of response to other-race compared to same-race faces for 9-month-olds only. More negative N290 amplitudes in response to happy compared to sad faces were found for 5-month-olds only. Nine-month-olds did not show different responses based on emotion, indicating that race was interfering with the processing of emotion.

Hole-Burning (HB) und Fluorescence Line-Narrowing (FLN) bei 4.2 K sowie Experimente zur Temperaturabhängigkeit werden angewendet, um Energieniveaustruktur und Elektron-Phonon- Wechselwirkung im Antennenkomplex LHC II grüner Pflanzen zu untersuchen. Besondere Aufmerksamkeit gilt dabei der Vermeidung systematischer Meßfehler durch Reabsorption von Fluoreszenz oder durch Lichtstreuung und unerwünschtes Lochbrennen bei FLN-Experimenten. Durch die Auswertung von Lochspektren können erstmals drei niederenergetische elektronische Zustände bei 677.1, 678.4 und 679.8 nm nachgewiesen werden. Die inhomogene Breite der zugehörigen Absorptionsbanden beträgt etwa 4 nm. Wahrscheinlich stellt jeder dieser Zustände das tiefste Energieniveau einer Untereinheit des LHC II-Trimers dar und ist weitgehend an jeweils einem Chl a-Molekül lokalisiert. Die energetische Differenz zwischen den drei Zuständen kann durch strukturelle Heterogenität erklärt werden. Es kann nachgewiesen werden, daß die Meßergebnisse praktisch frei von Effekten durch unerwünschte Aggregation sind. Die homogene Linienbreite des energetisch tiefsten Zustandes bei 4.7 K wird vorwiegend durch phasenzerstörende Prozesse (pure dephasing) bestimmt. Die Lochbreiten innerhalb der 650 nm Absorptionsbande entsprechen Chl b-Chl a Energietransferzeiten von 1 ps und etwa 240 fs bei 4.2 K, während Lochbreiten innerhalb der 676 nm Absorptionsbande Chl a-Chl a Energietransferzeiten in der Größenordnung von 6-10 ps ergeben. In einer theoretischen Betrachtung werden die Beiträge zu Phonon-Seitenbanden bei HB und FLN separat analysiert. Auf dieser Grundlage können Ergebnisse von HB und FLN Experimenten an LHC II erstmals in einem konsistenten Modell durch schwache Elektron-Phonon-Wechselwirkung mit einem Huang-Rhys-Faktor von 0.9 und ein breites, stark asymmetrisches Ein-Phonon-Profil erklärt werden. / Spectral hole-burning (HB) is combined with fluorescence line-narrowing (FLN) experiments at 4.2 K and studies of temperature-dependent fluorescence spectra in order to investigate low-energy level structure as well as electron-phonon coupling of the LHC II antenna complex of green plants. Special attention has been paid to eliminate effects owing to reabsorption of fluorescence and to assure that the FLN spectra are virtually unaffected by hole-burning or scattering artifacts. For the first time, analysis of the 4.2 K hole spectra reveals three low-energy electronic states at 677.1, 678.4 and 679.8 nm, respectively. The inhomogeneous width of their absorption bands is approximately 4 nm. It is likely that each of these states is associated with the lowest energy state of one trimer subunit with the energetic separations being due to structural heterogeneity. It is likely that each of the low-energy states is highly localized on a single Chl a molecule of the corresponding trimer subunit. The results are shown to be virtually free from aggregation effects. The homogeneous width for the lowest state at 4.7 K is predominantly due to pure dephasing. Widths of holes burned into the 650 nm absorption band correspond to Chl b-Chl a energy transfer times of 1 ps and about 240 fs at 4.2 K while holewidths for the 676 nm absorption band lead to Chl a-Chl a energy transfer times in the 6-10 ps range. The complexities associated with the interpretation of the phonon structure in HB and FLN spectra are discussed by theoretically analyzing the different phonon sideband contributions. On this basis, 4.2 K HB and FLN data can be consistently interpreted for the first time by weak electron-phonon coupling with a Huang-Rhys factor of about 0.9 to protein phonons with a broad and strongly asymmetric one- phonon profile.

No description available.

<p>This thesis discusses a new scheme for generating radiation in the mid infrared spectral region, especially the 3.5-5 µm range. The scheme uses established Nd³⁺-lasers at 1.06 µm and down conversion in nonlinear optical crystals. The down conversion is made by two optical parametric oscillators (OPO) in series. The second OPO is a classical OPO using a zink germanium phosphide (ZGP) crystal. ZGP is the best nonlinear material available for the 4-8 µm spectral range, but it is absorbing below 2 µm. The new development presented in this thesis is the OPO used to convert the 1.06 µm laser radiation to a suitable OPO pump near 2 µm.</p><p>The OPO uses a type I quasi phase-matched crystal, which accesses high nonlinearities and avoids walk-off. The problem with type I OPOs close to degeneracy is the broad bandwidth of the generated radiation, which reduces the efficiency of a second OPO. This has been solved with a spectrally selective cavity using a volume Bragg grating output coupler. Unlike other bandwidth limiting schemes this introduces no intracavity losses and thus efficient OPO operation is achievable.</p><p>Narrow linewidth (~0.5 nm) OPO operation has been achieved with periodically poled LiNbO₃ (PPLN) and periodically poled KTiOPO4 (PPKTP) while locking the signal wavelength at 2008 nm and simultaneously generating an idler at 2264 nm. A high average power PPLN OPO with 36 % conversion efficiency and 47 % slope efficiency is reported. Operation very close to degeneracy at 2128 nm with the narrowband signal and idler peaks separated by 0.6 nm was demonstrated in a PPKTP OPO. Both the signal at 2008 nm and the combined signal and idler around 2128 nm from the PPKTP OPOs have been used to show efficient pumping of a ZGP OPO. The maximum conversion efficiency from 1 µm to the mid-IR demonstrated is 7 % with a slope efficiency of 10 %. This is not quite as high as what has been presented by other authors, but the experiments reported here have not shown the optimum efficiency of the new scheme. Relatively simple improvements are expected to give a significant increase in conversion efficiency.</p>

Introduction: A computer-based classification system is proposed for the characterization of cervical intervertebral disc degeneration from saggital magnetic resonance images. Materials and methods: Cervical intervertebral discs from saggital magnetic resonance images where assessed by an experienced orthopaedist as normal or degenerated (narrowed) employing Matsumoto’s classification scheme. The digital images where enhanced and the intervertebral discs which comprised the regions of interest were segmented. First and second order statistics textural features extracted from thirty-four discs (16 normal and 16 degenerated) were used in order to design and test the classification system. In addition textural features were calculated employing Laws TEM images. The existence of statistically significant differences between the textural features values that were generated from normal and degenerated discs was verified employing the Student’s paired t-test. A subset with the most discriminating features (p<0.01) was selected and the Exhaustive Search and Leave-One-Out methods were used to find the best features combination and validate the classification accuracy of the system. The proposed system used the Least Squares Minimum Distance Classifier in combination with four textural features with comprised the best features combination in order to classify the discs as normal or degenerated. Results: The overall classification accuracy was 93.8% misdiagnosing 2 discs. In addition the system’s sensitivity in detecting a narrow disc was 93.8% and its specificity was also 93.8%. Conclusion: Further investigation and the use of a larger sample for validation could make the proposed system a trustworthy and useful tool to the physicians for the evaluation of degenerative disc disease in the cervical spine. / Σκοπός: Η στένωση των μεσοσπονδύλιων δίσκων της αυχενικής μοίρας, ως κύρια έκφραση εκφυλιστικής νόσου, είναι μια από τις σημαντικότερες αιτίες πρόκλησης πόνου στην περιοχή του αυχένα. Στην κλινική πράξη η αξιολόγηση της στένωσης γίνεται μέσω μέτρησης του μεσοσπονδύλιου διαστήματος, σε διάφορες απεικονίσεις της αυχενικής μοίρας του ασθενούς. Στην παρούσα εργασία προτείνεται μια υπολογιστική μέθοδος ανάλυσης εικόνας, για την αυτοματοποιημένη εκτίμηση της στένωσης από εικόνες μαγνητικής τομογραφίας. Υλικό και Μέθοδος: Μελετήθηκαν 34 μεσοσπονδύλιοι δίσκοι από οβελιαίες τομές μαγνητικής τομογραφίας της αυχενικής μοίρας, οι οποίες ελήφθησαν με χρήση Τ2 ακολουθίας. Η στένωση των μεσοσπονδύλιων δίσκων αξιολογήθηκε από έμπειρο ορθοπαιδικό βάσει της κλίμακας Matsumoto. Οι δίσκοι χωρίστηκαν σε δύο κατηγορίες: (α) 16 φυσιολογικοί και (β) 16 δίσκοι που παρουσίαζαν στένωση. Με χρήση διαδραστικού περιβάλλοντος επεξεργασίας εικάνας καθορίστηκε το περίγραμμα των μεσοσπονδύλιων δίσκων οι οποίοι αποτελούν τις προς ανάλυση περιοχές ενδιαφέροντος (Π.Ε.). Σε κάθε Π.Ε. εφαρμόστηκαν αλγόριθμοι εξαγωγής χαρακτηριστικών υφής. Συγκεκριμένα υπολογίστικαν χαρακτηριστικά υφής από στατιστικά πρώτης και δεύτερης τάξης καθώς και χαρακτηριστικά από τα μέτρα ενέργειας υφλης κατλα Laws. Τα παραπάνω χαρακτηριστικά, ποσοτικοποιούν διαγνωστικές πληροφορίες της έντασης του σήματος της Π.Ε. και συσχετίζονται με τη βιοχημική σύσταση των απεικονιζόμενων δομών. Τα εξαχθέντα χαρακτηριστικά υφής αξιοποιήθηκαν για τη σχεδίαση του ταξινομητή ελάχιστης απόστασης ελαχίστων τετραγώνων, ο οποίος χρησιμοποιήθηκε για το διαχωρισμό μεταξύ φυσιολογικών δίσκων και δίσκων που παρουσίαζαν στένωση (εκφυλισμένων). Αποτελέσματα: Η ακρίβεια της ταξινόμησης φυσιολογικών και εκφυλισμένων μεσοσπονδύλιων δίσκων ανήλθε σε 93.8%. Η ευαισθησία καθώς και η ειδικότητα της μεθόδου, σε ότι αφορά την ανίχνευση εκφυλισμένων δίσκων, είναι επίσης 93.8%. Συμπέρασμα: Με δεδομένο το μικρό μέγεθος του δείγματος που χρησιμοποιήθηκε για το σχεδιασμό της μεθόδου, απαιτούνται περετέρω εργασίες πιστοποίησης της ακρίβειας ταξινόμησης, προκειμένου η μέθοδος αυτή να αξιοποιηθεί από ακτινολόγους και ορθοπαιδικους, ως βοηθητικό διαγνωστικό εργαλείο.

Laser spectroscopic techniques have, during the last decades, demonstrated an extraordinary capability for sensitive detection of molecular constituents in gas phase. Since spectra from such techniques constitute unique and characteristic signatures for each type of species, these techniques enable investigations of molecular structures as well as detection of the presence of species in a gas mixture. They are therefore used for a variety of application, from fundamental studies to the assessment of gas concentrations. In fact, quantitative assessments of gas concentrations by laser-based techniques are constantly gaining in popularity, primarily due to properties such as high sensitivity and selectivity and an ability to perform non-invasive measurement. Moreover, investigations of isolated molecular transitions under different conditions provide excellent means to obtain a comprehensive understanding of spectral broadening mechanisms, which is of importance for, for example, environmental sciences and remote sensing applications. In fundamental studies, spectroscopic parameters are often retrieved from fits of a model function of the technique used, which in turn is based upon a suitable lineshape function. In order to obtain parameter values with highest possible accuracy, it is of importance to use the lineshape model that most correctly can predict the measured spectra. Even though the Voigt function is the most commonly used lineshape model when both Doppler and collision broadenings are present, it is not always suitable when spectroscopic parameters are to be assessed with high precision. This thesis represents a thorough investigation of Dicke narrowing and speed-dependent effects, which are phenomena that are not accounted for by the conventional Voigt profile. For the first time, it is demonstrated that both these effects take place not only in absorption but also in the dispersion mode of detection. Their dispersion lineshape functions are first theoretically presumed and explicitly given before they are validated experimentally by the noise-immune cavity-enhanced optical heterodyne molecular spectrometry (NICE-OHMS). By using the models developed, it is also shown that although the two modes of detection, absorption and dispersion, both can provide good quality of fits, they do not always provide identical spectroscopic parameters. A detailed analysis under which conditions they do so, and subsequent recommendations of their use, are presented. It also describes the instrumental implementation of a distributed-feed-back (DFB) laser-based NICE-OHMS instrumentation, which constitutes an important step towards the further development of this technique. Due to the wide tunability of the DFB laser, the setup is capable of extending the working range of NICE-OHMS into the collision broadening region, which, in turn, allows for precise spectroscopic studies. The use of a fiber-coupled DFB laser also provides a compact NICE-OHMS system. The minimum detectable on-resonance absorption was assessed to 2× 10-10 cm-1 for a 70 s integration time.

This thesis discusses a new scheme for generating radiation in the mid infrared spectral region, especially the 3.5-5 µm range. The scheme uses established Nd3+-lasers at 1.06 µm and down conversion in nonlinear optical crystals. The down conversion is made by two optical parametric oscillators (OPO) in series. The second OPO is a classical OPO using a zink germanium phosphide (ZGP) crystal. ZGP is the best nonlinear material available for the 4-8 µm spectral range, but it is absorbing below 2 µm. The new development presented in this thesis is the OPO used to convert the 1.06 µm laser radiation to a suitable OPO pump near 2 µm. The OPO uses a type I quasi phase-matched crystal, which accesses high nonlinearities and avoids walk-off. The problem with type I OPOs close to degeneracy is the broad bandwidth of the generated radiation, which reduces the efficiency of a second OPO. This has been solved with a spectrally selective cavity using a volume Bragg grating output coupler. Unlike other bandwidth limiting schemes this introduces no intracavity losses and thus efficient OPO operation is achievable. Narrow linewidth (~0.5 nm) OPO operation has been achieved with periodically poled LiNbO3 (PPLN) and periodically poled KTiOPO4 (PPKTP) while locking the signal wavelength at 2008 nm and simultaneously generating an idler at 2264 nm. A high average power PPLN OPO with 36 % conversion efficiency and 47 % slope efficiency is reported. Operation very close to degeneracy at 2128 nm with the narrowband signal and idler peaks separated by 0.6 nm was demonstrated in a PPKTP OPO. Both the signal at 2008 nm and the combined signal and idler around 2128 nm from the PPKTP OPOs have been used to show efficient pumping of a ZGP OPO. The maximum conversion efficiency from 1 µm to the mid-IR demonstrated is 7 % with a slope efficiency of 10 %. This is not quite as high as what has been presented by other authors, but the experiments reported here have not shown the optimum efficiency of the new scheme. Relatively simple improvements are expected to give a significant increase in conversion efficiency. / QC 20101108

La evaluación parcial (EP) de programas es una técnica formal para la especialización y optimización de programas. Un evaluador parcial toma un programa y sólo una parte de sus datos de entrada (los llamados datos estáticos) e intenta llevar a cabo todas las computaciones que sean posibles a partir de tales datos. El evaluador parcial devuelve un programa nuevo, denominado programa residual el cual se ejecuta generalmente de manera más e ciente que el programa original, ya que las computaciones que dependen de los datos estáticos se han realizado en la fase de evaluación parcial de una vez y para siempre [JGS93]. La evaluación parcial es una técnica de optimización de programas basada en semántica la cual ha sido investigada dentro de diferentes paradigmas de programación y aplicada a una amplia variedad de lenguajes. También es conocida como una técnica de transformación de programas fuente-a-fuente para especializar programas con respecto a una parte de sus datos de entrada (por ello también es conocida como especialización de programas). La evaluación parcial ha sido intensamente aplicada en el área de la programación funcional [CD93, JGS93, Tur86] y en programaci ón lógica [Gal93, Kom82b, LS91, PP94], donde ésta es normalmente conocida como deducción parcial. También en lenguajes imperativos como C en [TBC+98], o aplicada a un subconjunto importante de C en [And92] donde reportan la primera implementación autoaplicable de evaluación parcial para un lenguaje imperativo. Y en lenguajes formales como Scheme en [Jør92a, Jør92b] donde generan compiladores a partir de intérpretes. Cuando tenemos un programa sólo con algunos de sus datos de entrada conocidos no podemos ejecutar el programa, sin embargo podemos optimizar el programa computando respuestas tanto como sea posible. La evaluación parcial es una técnica que permite la ejecución parcial de un programa [MS97]. / Arroyo Delgado, G. (2012). Evaluación Parcial Offline Dirigida por Narrowing: Técnicas de Optimización y Aplicaciones [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/17655 / Palancia