Properties of gas and dark matter in X-ray galaxy clusters with Sunyaev Zel'dovich measurements

I have studied entropy profiles obtained in a sample of 24 X-ray objects at high redshift retrieved from the Chandra archive. I have discussed the scaling properties of the entropy S, the correlation between metallicity Z and S, the profiles of the temperature of the gas, Tgas, and performed a comparison between the dark matter 'temperature' and Tgas in order to constrain the non-gravitational processes which affect the thermal history of the gas. Furthermore I have studied the scaling relations between the X-ray quantities and Sunyaev Zel'dovich measurements. I have observed that X-ray laws are steeper than the relations predicted from the adiabatic model. These deviations from expectations based on self-similarity are usually interpreted in terms of feedback processes leading to non-gravitational gas heating, and suggesting a scenario in which the ICM at higher redshift has lower both X-ray luminosity and pressure in the central regions than the expectations from self-similar model. I have also investigated a Bayesian X-ray and Sunyaev Zel'dovich analysis, which allows to study the external regions of the clusters well beyond the volumes resolved with X-ray observations (1/3-1/2 of the virial radius), to measure the deprojected physical cluster properties, like temperature, density, entropy, gas mass and total mass up to the virial radius.

The incomplete ionization of substitutional dopants in Silicon Carbide

This thesis analyzes theoretically and computationally the phenomenon of partial ionization of the substitutional dopants in Silicon Carbide at thermal equilibrium. It is based on the solution of the charge neutrality equation and takes into account the following phenomena: several energy levels in the bandgap; Fermi-Dirac statistics for free carriers; screening effects on the dopant ionization energies; the formation of impurity bands. A self-consistent model and a corresponding simulation software have been realized. A preliminary comparison of our calculations with existing experimental results is carried out.

La fundamentación discursiva de la ética : Examen crítico de la reflexión trascendental y defensa del programa ético-discursivo en la versión de Karl-Otto Apel

El tema de la tesis es la fundamentación ético discursiva propuesta por Karl-Otto Apel en el marco de su pragmática trascendental. El examen crítico de esta propuesta filosófica tiene el objetivo de reforzar los argumentos a favor de una fundamentación trascendental de la ética. Se enfrenta inicialmente a la pragmática apeliana con una serie de críticas provenientes del debate analítico sobre los "argumentos trascendentales", iniciada en los años sesenta del siglo XX. Se reconstruyen tres líneas principales: una que atañe a la forma de los argumentos trascendentales, otra a su capacidad para demostrar validez objetiva, y la otra a su capacidad para demostrar la unicidad de un esquema conceptual (iniciadas respectivamente por M. Gram, B. Stroud y S. Körner). La discusión y posterior aplicación a Apel de las críticas de este debate conduce a tres conclusiones principales. La primera es que no existen razones concluyentes en contra de realizar una reflexión trascendental sobre las condiciones de posibilidad del conocimiento válido. La segunda es que la fundamentación trascendental debe hacerse en el marco de un modelo filosófico dialógico y auto-reflexivo (diferente al asumido por los autores del debate). Precisamente, la tercera conclusión es que todo método trascendental debe ser "interno", es decir, debe asumir las condiciones que investiga. Se aborda entonces el problema de concebir un método que asuma la circularidad de la investigación y le dé un contenido concreto a la fundamentación. En lugar de la fórmula apeliana, se sostiene la conveniencia de entender la pragmática trascendental como una continuación, corregida en un sentido trascendental, de la hermenéutica iniciada por Heidegger y renovada por Gadamer. Un método interno "hermenéutico trascendental" puede describirse con los rasgos de la dialogicidad, la auto-reflexión y la crítica del sentido. El interés fundamental es, como para Apel, la reconstrucción de aquellos presupuestos que conforman la base de la ética discursiva, la cual transforma de manera comunicativa el imperativo categórico kantiano. Se discute finalmente la cuestión de cómo es posible pensar que los presupuestos argumentativos no están sometidos a cambios históricos. La respuesta apunta a señalar que la objeción de "otra razón posible" carece de argumentos sustantivos en contra de la fundamentación.

La fundamentación discursiva de la ética : Examen crítico de la reflexión trascendental y defensa del programa ético-discursivo en la versión de Karl-Otto Apel

El tema de la tesis es la fundamentación ético discursiva propuesta por Karl-Otto Apel en el marco de su pragmática trascendental. El examen crítico de esta propuesta filosófica tiene el objetivo de reforzar los argumentos a favor de una fundamentación trascendental de la ética. Se enfrenta inicialmente a la pragmática apeliana con una serie de críticas provenientes del debate analítico sobre los "argumentos trascendentales", iniciada en los años sesenta del siglo XX. Se reconstruyen tres líneas principales: una que atañe a la forma de los argumentos trascendentales, otra a su capacidad para demostrar validez objetiva, y la otra a su capacidad para demostrar la unicidad de un esquema conceptual (iniciadas respectivamente por M. Gram, B. Stroud y S. Körner). La discusión y posterior aplicación a Apel de las críticas de este debate conduce a tres conclusiones principales. La primera es que no existen razones concluyentes en contra de realizar una reflexión trascendental sobre las condiciones de posibilidad del conocimiento válido. La segunda es que la fundamentación trascendental debe hacerse en el marco de un modelo filosófico dialógico y auto-reflexivo (diferente al asumido por los autores del debate). Precisamente, la tercera conclusión es que todo método trascendental debe ser "interno", es decir, debe asumir las condiciones que investiga. Se aborda entonces el problema de concebir un método que asuma la circularidad de la investigación y le dé un contenido concreto a la fundamentación. En lugar de la fórmula apeliana, se sostiene la conveniencia de entender la pragmática trascendental como una continuación, corregida en un sentido trascendental, de la hermenéutica iniciada por Heidegger y renovada por Gadamer. Un método interno "hermenéutico trascendental" puede describirse con los rasgos de la dialogicidad, la auto-reflexión y la crítica del sentido. El interés fundamental es, como para Apel, la reconstrucción de aquellos presupuestos que conforman la base de la ética discursiva, la cual transforma de manera comunicativa el imperativo categórico kantiano. Se discute finalmente la cuestión de cómo es posible pensar que los presupuestos argumentativos no están sometidos a cambios históricos. La respuesta apunta a señalar que la objeción de "otra razón posible" carece de argumentos sustantivos en contra de la fundamentación.

La fundamentación discursiva de la ética : Examen crítico de la reflexión trascendental y defensa del programa ético-discursivo en la versión de Karl-Otto Apel

El tema de la tesis es la fundamentación ético discursiva propuesta por Karl-Otto Apel en el marco de su pragmática trascendental. El examen crítico de esta propuesta filosófica tiene el objetivo de reforzar los argumentos a favor de una fundamentación trascendental de la ética. Se enfrenta inicialmente a la pragmática apeliana con una serie de críticas provenientes del debate analítico sobre los "argumentos trascendentales", iniciada en los años sesenta del siglo XX. Se reconstruyen tres líneas principales: una que atañe a la forma de los argumentos trascendentales, otra a su capacidad para demostrar validez objetiva, y la otra a su capacidad para demostrar la unicidad de un esquema conceptual (iniciadas respectivamente por M. Gram, B. Stroud y S. Körner). La discusión y posterior aplicación a Apel de las críticas de este debate conduce a tres conclusiones principales. La primera es que no existen razones concluyentes en contra de realizar una reflexión trascendental sobre las condiciones de posibilidad del conocimiento válido. La segunda es que la fundamentación trascendental debe hacerse en el marco de un modelo filosófico dialógico y auto-reflexivo (diferente al asumido por los autores del debate). Precisamente, la tercera conclusión es que todo método trascendental debe ser "interno", es decir, debe asumir las condiciones que investiga. Se aborda entonces el problema de concebir un método que asuma la circularidad de la investigación y le dé un contenido concreto a la fundamentación. En lugar de la fórmula apeliana, se sostiene la conveniencia de entender la pragmática trascendental como una continuación, corregida en un sentido trascendental, de la hermenéutica iniciada por Heidegger y renovada por Gadamer. Un método interno "hermenéutico trascendental" puede describirse con los rasgos de la dialogicidad, la auto-reflexión y la crítica del sentido. El interés fundamental es, como para Apel, la reconstrucción de aquellos presupuestos que conforman la base de la ética discursiva, la cual transforma de manera comunicativa el imperativo categórico kantiano. Se discute finalmente la cuestión de cómo es posible pensar que los presupuestos argumentativos no están sometidos a cambios históricos. La respuesta apunta a señalar que la objeción de "otra razón posible" carece de argumentos sustantivos en contra de la fundamentación.

Multiwavelength study of quiescent states of MrK 421 with unprecedented hard x-Ray coverage provided by NuStar in 2013

We present coordinated multiwavelength observations of the bright, nearby BL Lacertae object Mrk 421 taken in 2013 January–March, involving GASP-WEBT, Swift, NuSTAR, Fermi-LAT, MAGIC, VERITAS, and other collaborations and instruments, providing data from radio to very high energy (VHE) γ-ray bands. NuSTAR yielded previously unattainable sensitivity in the 3–79 keV range, revealing that the spectrum softens when the source is dimmer until the X-ray spectral shape saturates into a steep G » 3 power law, with no evidence for an exponential cutoff or additional hard components up "aprox" 80keV. For the first time, we observed both the synchrotron and the inverse-Compton peaks of the spectral energy distribution (SED) simultaneously shifted to frequencies below the typical quiescent state by an order of magnitude. The fractional variability as a function of photon energy shows a double-bump structure that relates to the two bumps of the broadband SED. In each bump, the variability increases with energy, which, in the framework of the synchrotron self-Compton model, implies that the electrons with higher energies are more variable. The measured multi band variability, the significant X-ray-toVHE correlation down to some of the lowest fluxes ever observed in both bands, the lack of correlation between optical/UV and X-ray flux, the low degree of polarization and its significant (random) variations, the short estimated electron cooling time, and the significantly longer variability timescale observed in the NuSTAR light curves point toward in situ electron acceleration and suggest that there are multiple compact regions contributing to the broadband emission of Mrk 421 during low-activity states.

Growing Neural Gas approach for obtaining homogeneous maps by restricting the insertion of new nodes

The Growing Neural Gas model is used widely in artificial neural networks. However, its application is limited in some contexts by the proliferation of nodes in dense areas of the input space. In this study, we introduce some modifications to address this problem by imposing three restrictions on the insertion of new nodes. Each restriction aims to maintain the homogeneous values of selected criteria. One criterion is related to the square error of classification and an alternative approach is proposed for avoiding additional computational costs. Three parameters are added that allow the regulation of the restriction criteria. The resulting algorithm allows models to be obtained that suit specific needs by specifying meaningful parameters.

The effective use of implicit parallelism through the use of an object-oriented programming language

This thesis explores translating well-written sequential programs in a subset of the Eiffel programming language - without syntactic or semantic extensions - into parallelised programs for execution on a distributed architecture. The main focus is on constructing two object-oriented models: a theoretical self-contained model of concurrency which enables a simplified second model for implementing the compiling process. There is a further presentation of principles that, if followed, maximise the potential levels of parallelism. Model of Concurrency. The concurrency model is designed to be a straightforward target for mapping sequential programs onto, thus making them parallel. It aids the compilation process by providing a high level of abstraction, including a useful model of parallel behaviour which enables easy incorporation of message interchange, locking, and synchronization of objects. Further, the model is sufficient such that a compiler can and has been practically built. Model of Compilation. The compilation-model's structure is based upon an object-oriented view of grammar descriptions and capitalises on both a recursive-descent style of processing and abstract syntax trees to perform the parsing. A composite-object view with an attribute grammar style of processing is used to extract sufficient semantic information for the parallelisation (i.e. code-generation) phase. Programming Principles. The set of principles presented are based upon information hiding, sharing and containment of objects and the dividing up of methods on the basis of a command/query division. When followed, the level of potential parallelism within the presented concurrency model is maximised. Further, these principles naturally arise from good programming practice. Summary. In summary this thesis shows that it is possible to compile well-written programs, written in a subset of Eiffel, into parallel programs without any syntactic additions or semantic alterations to Eiffel: i.e. no parallel primitives are added, and the parallel program is modelled to execute with equivalent semantics to the sequential version. If the programming principles are followed, a parallelised program achieves the maximum level of potential parallelisation within the concurrency model.

Structure of dysprosium and holmium phosphate glasses by the method of isomorphic substitution in neutron diffraction

The relative distribution of rare-earth ions R3+ (Dy3+ or Ho3+) in the phosphate glass RAl0.30P3.05O9.62 was measured by employing the method of isomorphic substitution in neutron diffraction and, by taking the role of Al into explicit account, a self-consistent model of the glass structure was developed. The glass network is found to be made from corner sharing PO4 tetrahedra in which there are, on average, 2.32(9) terminal oxygen atoms, OT, at 1.50(1) Å and 1.68(9) bridging oxygen atoms, OB, at 1.60(1) Å. The network modifying R3+ ions bind to an average of 6.7(1) OT and are distributed such that 7.9(7) R–R nearest neighbours reside at 5.62(6) Å. The Al3+ ion also has a network modifying role in which it helps to strengthen the glass through the formation of OT–Al–OT linkages. The connectivity of the R-centred coordination polyhedra in (M2O3)x(P2O5)1−x glasses, where M3+ denotes a network modifying cation (R3+ or Al3+), is quantified in terms of a parameter fs. Methods for reducing the clustering of rare-earth ions in these materials are then discussed, based on a reduction of fs via the replacement of R3+ by Al3+ at fixed total modifier content or via a change of x to increase the number of OT available per network modifying M3+ cation.

Structure of lanthanum and cerium phosphate glasses by the method of isomorphic substitution in neutron diffraction

Neutron diffraction was used to measure the total structure factors for several rare-earth ion R3+ (La3+ or Ce3+) phosphate glasses with composition close to RAl0.35P3.24O10.12. By assuming isomorphic structures, difference function methods were employed to separate, essentially, those correlations involving R3+ from the remainder. A self-consistent model of the glass structure was thereby developed in which the Al correlations were taken into explicit account. The glass network was found to be made from interlinked PO4 tetrahedra having 2.2(1) terminal oxygen atoms, OT, at 1.51(1) Angstrom, and 1.8(1) bridging oxygen atoms, OB, at 1.60(1) Angstrom. Rare-earth cations bonded to an average of 7.5(2) OT nearest neighbors in a broad and asymmetric distribution. The Al3+ ion acted as a network modifier and formed OT-A1-OT linkages that helped strengthen the glass. The connectivity of the R-centered coordination polyhedra was quantified in terms of a parameter f(s) and used to develop a model for the dependence on composition of the A1-OT coordination number in R-A1-P-O glasses. By using recent 17 A1 nuclear-magnetic-resonance data, it was shown that this connectivity decreases monotonically with increasing Al content. The chemical durability of the glasses appeared to be at a maximum when the connectivity of the R-centered coordination polyhedra was at a minimum. The relation of f(s) to the glass transition temperature, Tg, was discussed.

A developmental intervention science outreach research approach to promoting positive youth development

Recent intervention efforts in promoting positive identity in troubled adolescents have begun to draw on the potential for an integration of the self-construction and self-discovery perspectives in conceptualizing identity processes, as well as the integration of quantitative and qualitative data analytic strategies. This study reports an investigation of the Changing Lives Program (CLP), using an Outcome Mediation (OM) evaluation model, an integrated model for evaluating targets of intervention, while theoretically including a Self-Transformative Model of Identity Development (STM), a proposed integration of self-discovery and self-construction identity processes. This study also used a Relational Data Analysis (RDA) integration of quantitative and qualitative analysis strategies and a structural equation modeling approach (SEM), to construct and evaluate the hypothesized OM/STM model. The CLP is a community supported positive youth development intervention, targeting multi-problem youth in alternative high schools in the Miami Dade County Public Schools (M-DCPS). The 259 participants for this study were drawn from the CLP’s archival data file. The model evaluated in this study utilized three indices of core identity processes (1) personal expressiveness, (2) identity conflict resolution, and (3) informational identity style that were conceptualized as mediators of the effects of participation in the CLP on change in two qualitative outcome indices of participants’ sense of self and identity. Findings indicated the model fit the data (χ2 (10) = 3.638, p = .96; RMSEA = .00; CFI = 1.00; WRMR = .299). The pattern of findings supported the utilization of the STM in conceptualizing identity processes and provided support for the OM design. The findings also suggested the need for methods capable of detecting and rendering unique sample specific free response data to increase the likelihood of identifying emergent core developmental research concepts and constructs in studies of intervention/developmental change over time in ways not possible using fixed response methods alone.

3D Ionospheric Effects on HF Propagation and Heating

The thesis uses a three-dimensional, first-principles model of the ionosphere in combination with High Frequency (HF) raytracing model to address key topics related to the physics of HF propagation and artificial ionospheric heating. In particular: 1. Explores the effect of the ubiquitous electron density gradients caused by Medium Scale Traveling Ionospheric Disturbances (MSTIDs) on high-angle of incidence HF radio wave propagation. Previous studies neglected the all-important presence of horizontal gradients in both the cross- and down-range directions, which refract the HF waves, significantly changing their path through the ionosphere. The physics-based ionosphere model SAMI3/ESF is used to generate a self-consistently evolving MSTID that allows for the examination of the spatio-temporal progression of the HF radio waves in the ionosphere. 2. Tests the potential and determines engineering requirements for ground- based high power HF heaters to trigger and control the evolution of Equatorial Spread F (ESF). Interference from ESF on radio wave propagation through the ionosphere remains a critical issue on HF systems reliability. Artificial HF heating has been shown to create plasma density cavities in the ionosphere similar to those that may trigger ESF bubbles. The work explores whether HF heating may trigger or control ESF bubbles. 3. Uses the combined ionosphere and HF raytracing models to create the first self-consistent HF Heating model. This model is utilized to simulate results from an Arecibo experiment and to provide understanding of the physical mechanism behind observed phenomena. The insights gained provide engineering guidance for new artificial heaters that are being built for use in low to middle latitude regions. In accomplishing the above topics: (i) I generated a model MSTID using the SAMI3/ESF code, and used a raytrace model to examine the effects of the MSTID gradients on radio wave propagation observables; (ii) I implemented a three- dimensional HF heating model in SAMI3/ESF and used the model to determine whether HF heating could artificially generate an ESF bubble; (iii) I created the first self-consistent model for artificial HF heating using the SAMI3/ESF ionosphere model and the MoJo raytrace model and ran a series of simulations that successfully modeled the results of early artificial heating experiments at Arecibo.

Finnish Preclinical and Clinical Medical Students as Strategic L2 English Learners: Language Learning Strategies and Communicating with Patients

This thesis focused on medical students’ language learning strategies for patient encounters. The research questions concerned the types of learning strategies that medical students use and the differences between the preclinical students and the clinical students, two groups who have had varying amounts of experience with patients. Additionally, strategy use was examined through activity systems to gain information on the context of language learning strategy use in order to learn language for patient encounters. In total, 130 first-year medical students (preclinical) and 39 fifth-year medical students (clinical) participated in the study by filling in a questionnaire on language learning strategies. In addition, two students were interviewed in order to create activity systems for the medical students at different stages of their studies. The study utilised both quantitative and qualitative research methods; the analysis of the results relies on Oxford’s Strategic Self-Regulation Model in the quantitative part and on activity theory in the qualitative part. The theoretical sections of the study introduced earlier research and theories regarding English for specific purposes, language learning strategies and activity theory. The results indicated that the medical students use affective, sociocultural-interactive and metasociocultural-interactive strategies often and avoid using negative strategies, which hinder language learning or cease communication altogether. Slight differences between the preclinical and clinical students were found, as clinical students appear to use affective and metasociocultural-interactive strategies more frequently compared to the preclinical students. The activity systems of the two students interviewed were rather similar. The students were at different stages of their studies, but their opinions were very similar. Both reported the object of learning to be mutual understanding between the patient and the doctor, which in part explains the preference for strategies that support communication and interaction. The results indicate that the nature of patient encounters affects the strategy use of the medical students at least to some extent.

Coordinated pricing and inventory management

This dissertation mainly focuses on coordinated pricing and inventory management problems, where the related background is provided in Chapter 1. Several periodic-review models are then discussed in Chapters 2,3,4 and 5, respectively. Chapter 2 analyzes a deterministic single-product model, where a price adjustment cost incurs if the current selling price is changed from the previous period. We develop exact algorithms for the problem under different conditions and find out that computation complexity varies significantly associated with the cost structure. %Moreover, our numerical study indicates that dynamic pricing strategies may outperform static pricing strategies even when price adjustment cost accounts for a significant portion of the total profit. Chapter 3 develops a single-product model in which demand of a period depends not only on the current selling price but also on past prices through the so-called reference price. Strongly polynomial time algorithms are designed for the case without no fixed ordering cost, and a heuristic is proposed for the general case together with an error bound estimation. Moreover, our illustrates through numerical studies that incorporating reference price effect into coordinated pricing and inventory models can have a significant impact on firms' profits. Chapter 4 discusses the stochastic version of the model in Chapter 3 when customers are loss averse. It extends the associated results developed in literature and proves that the reference price dependent base-stock policy is proved to be optimal under a certain conditions. Instead of dealing with specific problems, Chapter 5 establishes the preservation of supermodularity in a class of optimization problems. This property and its extensions include several existing results in the literature as special cases, and provide powerful tools as we illustrate their applications to several operations problems: the stochastic two-product model with cross-price effects, the two-stage inventory control model, and the self-financing model.

Investigating the peculiar emission from the new VHE gamma-ray source H1722+119

The MAGIC (Major Atmospheric Gamma-ray Imaging Cherenkov) telescopes observed the BL Lac object H1722+119 (redshift unknown) for six consecutive nights between 2013 May 17 and 22, for a total of 12.5 h. The observations were triggered by high activity in the optical band measured by the KVA (Kungliga Vetenskapsakademien) telescope. The source was for the first time detected in the very high energy (VHE, E > 100 GeV) γ-ray band with a statistical significance of 5.9 σ. The integral flux above 150 GeV is estimated to be (2.0 ± 0.5) per cent of the Crab Nebula flux. We used contemporaneous high energy (HE, 100MeV < E < 100 GeV) γ-ray observations from Fermi-LAT (Large Area Telescope) to estimate the redshift of the source. Within the framework of the current extragalactic background light models, we estimate the redshift to be z = 0.34±0.15. Additionally, we used contemporaneous X-ray to radio data collected by the instruments on board the Swift satellite, the KVA, and the OVRO (Owens Valley Radio Observatory) telescope to study multifrequency characteristics of the source. We found no significant temporal variability of the flux in the HE and VHE bands. The flux in the optical and radio wavebands, on the other hand, did vary with different patterns. The spectral energy distribution (SED) of H1722+119 shows surprising behaviour in the ∼ 3×1014 −1018 Hz frequency range. It can be modelled using an inhomogeneous helical jet synchrotron self-Compton model.