Essays on numerically efficient inference in nonlinear and non-Gaussian state space models, and commodity market analysis.

The first two articles build procedures to simulate vector of univariate states and estimate parameters in nonlinear and non Gaussian state space models. We propose state space speci fications that offer more flexibility in modeling dynamic relationship with latent variables. Our procedures are extension of the HESSIAN method of McCausland[2012]. Thus, they use approximation of the posterior density of the vector of states that allow to : simulate directly from the state vector posterior distribution, to simulate the states vector in one bloc and jointly with the vector of parameters, and to not allow data augmentation. These properties allow to build posterior simulators with very high relative numerical efficiency. Generic, they open a new path in nonlinear and non Gaussian state space analysis with limited contribution of the modeler. The third article is an essay in commodity market analysis. Private firms coexist with farmers' cooperatives in commodity markets in subsaharan african countries. The private firms have the biggest market share while some theoretical models predict they disappearance once confronted to farmers cooperatives. Elsewhere, some empirical studies and observations link cooperative incidence in a region with interpersonal trust, and thus to farmers trust toward cooperatives. We propose a model that sustain these empirical facts. A model where the cooperative reputation is a leading factor determining the market equilibrium of a price competition between a cooperative and a private firm

Synthesis and Characterization Of Some Transition Metal Complexes Of Multidentate Ligands

Coordination chemistry of schiff bases is of considerable interest due to their various magnetic, catalytic and biological applications. Here it describes the spectral characterization of schiff bases and its Mn (II), Cu (II) and Ni (II) complexes. Then synthesis and spectral characterization of Zn (II), Cd (II) and Co (II) complexes of schiff base derived from 3-Formylsalicilic Acid and 1,3-diaminopropane. Then it discusses the synthesis and spectral studies of Copper (II) complexes of 2-Hydroxyacetophenone N-phenyl semicarbazone. Finally it discusses the synthesis and spectral characterization of Co (III) complexes of salicylaldehyde N-phenyl semicarbazone. The preparation and characterization of Cobalt (III) complexes of salicylaldehyde, N-phenylthiosemicarbazone containing hetrocyclic bases phenalthroline and bipyridine. Thiocyanate, azide and perchlorate ions act as coligands. Elemental analysis suggests +3 state for Cobalt. HNMR, IR and UV-visible spectra characterize the complexes.

The Steady-State and Transient Characteristic Analysis of Thermal Fixing a Photorefractive Hologram Grating in Lithium Niobate

The transient interaction between a refraction index grating and light beams during simultaneous writing and thermal fixing of a photorefractive hologram is investigated. With a diffusion- and photovoltaic-dominated carrier transport mechanism and carrier thermal activation (temperature dependent) considered in Fe:LiNbO3 crystal, from the standpoint of field-material coupling, the theoretical thermal fixing time and the space-charge field buildup, spatial distribution, and temperature dependence are given numerically by combining the band transport model with mobile ions with the coupled-wave equation

Kinetics of martensitic transitions in Cu-Al-Mn under thermal cycling: Analysis at multiple length scales

In this paper we study the evolution of the kinetic features of the martensitic transition in a Cu-Al-Mn single crystal under thermal cycling. The use of several experimental techniques including optical microscopy, calorimetry, and acoustic emission, has enabled us to perform an analysis at multiple scales. In particular, we have focused on the analysis of avalanche events (associated with the nucleation and growth of martensitic domains), which occur during the transition. There are significant differences between the kinetics at large and small length scales. On the one hand, at small length scales, small avalanche events tend to sum to give new larger events in subsequent loops. On the other hand, at large length scales the large domains tend to split into smaller ones on thermal cycling. We suggest that such different behavior is the necessary ingredient that leads the system to the final critical state corresponding to a power-law distribution of avalanches.

X-ray diffraction, thermal analysis, and Raman scattering study of K2BeF4 and comparation to other member of the (beta)-K2SO4 family with ferroelectric -paraelectric transition

Thermal analysis, powder diffraction, and Raman scattering as a function of the temperature were carried out on K2BeF4. Moreover, the crystal structure was determined at 293 K from powder diffraction. The compound shows a transition from Pna21 to Pnam space group at 921 K with a transition enthalpy of 5 kJ/mol. The transition is assumed to be first order because the compound shows metastability. Structurally and spectroscopically the transition is similar to those observed in (NH4)2SO4, which suggests that the low-temperature phase is ferroelectric. In order to confirm it, the spontaneous polarization has been computed using an ionic model.

Adsorption energy and spin state of first-row transition metals adsorbed on MgO(100)

Slab and cluster model spin-polarized calculations have been carried out to study various properties of isolated first-row transition metal atoms adsorbed on the anionic sites of the regular MgO(100) surface. The calculated adsorption energies follow the trend of the metal cohesive energies, indicating that the changes in the metal-support and metal-metal interactions along the series are dominated by atomic properties. In all cases, except for Ni at the generalized gradient approximation level, the number of unpaired electron is maintained as in the isolated metal atom. The energy required to change the atomic state from high to low spin has been computed using the PW91 and B3LYP density-functional-theory-based methods. PW91 fails to predict the proper ground state of V and Ni, but the results for the isolated and adsorbed atom are consistent within the method. B3LYP properly predicts the ground state of all first-row transition atom the high- to low-spin transition considered is comparable to experiment. In all cases, the interaction with the surface results in a reduced high- to low-spin transition energy.

Ionic-covalent transition in titanium oxides

The nature of the chemical bond in three titanium oxides of different crystal structure and different formal oxidation state has been studied by means of the ab initio cluster-model approach. The covalent and ionic contributions to the bond have been measured from different theoretical techniques. All the analysis is consistent with an increasing of covalence in the TiO, Ti2O3, and TiO2 series as expected from chemical intuition. Moreover, the use of the ab initio cluster-model approach combined with different theoretical techniques has permitted us to quantify the degree of ionic character, showing that while TiO can approximately be described as an ionic compound, TiO2 is better viewed as a rather covalent oxide.

Innovation and Globalization Policy in Small Transition Countries ; Case study: Macedonia and Slovenia

Diese Arbeit befasst sich mit der Innovations- und Globalisierungspolitik in kleinen Transformationsländern am Beispiel Mazedoniens; diese wurde mit der Lage in Slowenien verglichen, einem Land von ungefähr gleicher Größe und mit gemeinsamer Vergangenheit als Teilrepublik der Jugoslawischen Föderation, aber mit einem wesentlich höheren ökonomischen Entwicklungsstand. Innovation wird dabei verstanden als „Herstellung, Anpassung und Ausnutzung von Neuerungen“, und sie wird durch das Umfeld, in dem sie stattfindet, beeinflusst. Anpassung und Ausnutzung sind gerade für kleine Transformationsländer von erheblicher Bedeutung, da ihre Fähigkeit zu Herstellung von Neuerungen sehr begrenzt sind. Die Rolle der Innovationspolitik besteht hierbei darin, institutionelle und organisationelle Regulierungen einzuführen, die ein günstiges Umfeld sowohl für Innovationen als auch für die Entwicklung eines nationalen Innovationssystems schaffen. Die Rolle der Politik besteht also nicht in der Innovation als solcher, sondern in der Herstellung der notwendigen Bedingungen für die Industrie und die Forschungseinrichtungen dahingehend zu schaffen, dass sie ihr Wissen, ihre Fertigkeiten und ihre praktischen Erfahrungen für innovative Tätigkeiten einsetzen können. Auf der einen Seite gibt es Institutionen und Organisationen, ohne die die Unternehmen rückständig und wenig leistungsstark wären (etwa das Patentamt oder Institutionen höherer Bildung), und auf der anderen Seite gibt es Institutionen und Organisationen, welche die Unternehmen dabei unterstützen, dass sie ihre Tätigkeit weiter unterstützen (z.B. durch Technologietransfer-Zentren und Netzwerke). Die Leistungen dieser Institutionen und Organisationen sind von großer Bedeutung für die nationalen Innovationssysteme und sollten ihrerseits durch Innovationspolitik unterstützt werden; dies bedeutet jedoch nicht, dass diese Leistungen vom Staat bereitgestellt werden, vielmehr sollte die Wirtschaftspolitik Möglichkeiten für die öffentlich/private oder sogar rein private Bereitstellung solcher Leistungen in Erwägung ziehen; dies würde nicht nur die Kosten für den Staat senken, sondern auch die Effizienz bei der Erstellung dieser Leistungen steigern. Die Arbeit kommt zu dem Schluss, dass das größte Problem der Innovationspolitik in Mazedonien darin besteht, dass es sie gar nicht gibt, und zwar nicht als Folge einer bewussten Entscheidung darüber. Tatsächlich müssen Ressourcen und Zeit für die Schaffung eines nationalen Innovationssystems eingesetzt werden mit Hilfe einer Politik, die sich auf die wesentlichen Umrisse konzentriert, wobei die Nachfrage nach Technologie im Unternehmensbereich gesteigert wird und das Wissen und das Informationsangebot restrukturiert wird. Dieses System muss offen sein, unter beständigem Verbesserungsdruck stehen und fähig sein, sich an Veränderungen anzupassen. Damit eine solche Politik erfolgreich ist, muss es einen Konsens darüber zwischen allen beteiligten Akteuren geben und darüber hinaus auch eine Kohärenz zwischen den verschiedenen politischen Institutionen. Das ist deswegen wichtig, weil der Innovationsprozess komplex ist und verschiedene Politikbereiche berührt. Ziel sollte die Schaffung eines Systems sein, das einerseits auf Autonomie und Kooperation aufbaut, andererseits aber auch Wettbewerb zwischen den beteiligten Institutionen und Organisationen fördert. Eine wichtige Bedingung für ein positives Investitionsklima im Bereich der Innovation ist die Erreichung von makroökonomischer Stabilität. Die gegenwärtige Situation ist gekennzeichnet durch Instabilität des Rechtswesens, durch Korruption und Probleme des Vertragsschutzes, die sowohl ausländische als auch inländische Akteure davon abhält, sich in wirtschaftlichen Aktivitäten in Mazedonien zu engagieren. Bei der Suche nach einem Ausweg aus diesen Problemen ist es wichtig für Mazedonien, von anderen Ländern wie Slowenien zu lernen, die ähnliche Probleme haben, aber auch schon Erfahrungen in der Problemlösung. Man muss dabei beachten, dass der Entwicklungsstand, das wirtschaftliche und das politische Umfeld in beiden Vergleichsländern sich erheblich unterscheiden, so dass die Lektionen, die Mazedonien von Slowenien lernen könnte, nicht direkt übertragen und kopiert werden können, sondern entsprechend angepasst werden müssen. Die vorliegende Arbeit liefert Einsichten in die Probleme der Innovationspolitik in Transformationsländern und liefert daher sowohl einen Anreiz als auch eine Quelle von Informationen für künftige Analysen der wirtschaftlichen Bedingungen und vor allem Innovationspolitik in Transformationsländern.

State dependent volume isotope shift analysis of the low lying states of Ba I and Ba II

Relativistic multi-configuration Dirac-Fock wavefunctions, coupled to good angular momentum J, have been calculated for low lying states of Ba I and Ba II. The resulting electronic factors show good agreement with data derived from recent high-resolution laser spectroscopy experiments and results from a comparison of muonic and optical data.

Theoretical study of magnetism, structure and chemical order in transition-metal alloy clusters

Research on transition-metal nanoalloy clusters composed of a few atoms is fascinating by their unusual properties due to the interplay among the structure, chemical order and magnetism. Such nanoalloy clusters, can be used to construct nanometer devices for technological applications by manipulating their remarkable magnetic, chemical and optical properties. Determining the nanoscopic features exhibited by the magnetic alloy clusters signifies the need for a systematic global and local exploration of their potential-energy surface in order to identify all the relevant energetically low-lying magnetic isomers. In this thesis the sampling of the potential-energy surface has been performed by employing the state-of-the-art spin-polarized density-functional theory in combination with graph theory and the basin-hopping global optimization techniques. This combination is vital for a quantitative analysis of the quantum mechanical energetics. The first approach, i.e., spin-polarized density-functional theory together with the graph theory method, is applied to study the Fe$_m$Rh$_n$ and Co$_m$Pd$_n$ clusters having $N = m+n \leq 8$ atoms. We carried out a thorough and systematic sampling of the potential-energy surface by taking into account all possible initial cluster topologies, all different distributions of the two kinds of atoms within the cluster, the entire concentration range between the pure limits, and different initial magnetic configurations such as ferro- and anti-ferromagnetic coupling. The remarkable magnetic properties shown by FeRh and CoPd nanoclusters are attributed to the extremely reduced coordination number together with the charge transfer from 3$d$ to 4$d$ elements. The second approach, i.e., spin-polarized density-functional theory together with the basin-hopping method is applied to study the small Fe$_6$, Fe$_3$Rh$_3$ and Rh$_6$ and the larger Fe$_{13}$, Fe$_6$Rh$_7$ and Rh$_{13}$ clusters as illustrative benchmark systems. This method is able to identify the true ground-state structures of Fe$_6$ and Fe$_3$Rh$_3$ which were not obtained by using the first approach. However, both approaches predict a similar cluster for the ground-state of Rh$_6$. Moreover, the computational time taken by this approach is found to be significantly lower than the first approach. The ground-state structure of Fe$_{13}$ cluster is found to be an icosahedral structure, whereas Rh$_{13}$ and Fe$_6$Rh$_7$ isomers relax into cage-like and layered-like structures, respectively. All the clusters display a remarkable variety of structural and magnetic behaviors. It is observed that the isomers having similar shape with small distortion with respect to each other can exhibit quite different magnetic moments. This has been interpreted as a probable artifact of spin-rotational symmetry breaking introduced by the spin-polarized GGA. The possibility of combining the spin-polarized density-functional theory with some other global optimization techniques such as minima-hopping method could be the next step in this direction. This combination is expected to be an ideal sampling approach having the advantage of avoiding efficiently the search over irrelevant regions of the potential energy surface.

Description and analysis of pulmonary rehabilitation care programs current state in four cities of Colombia

Purpose: there are many studies reporting the benefits of pulmonary rehabilitation, but few of them exhibit the behavior and activities of these services. This article presents the characteristics of services, parts management and training level of team members, in addition to the variables or instruments used to measure the effectiveness and impact in these programs. Method: it was made a cross sectional convenience sample which included seven pulmonary rehabilitation services in four Colombian cities (Bogotá, Medellín, Manizales and Cali), selected by the coverage, for having at least one year of experience and for being formally established and recognized nationwide. The interdisciplinary team of each service answered a survey that was validated through a pilot test and expert consensus. Participation was voluntary. Results: labor onset pulmonary rehabilitation services correspond to an average of a decade, with COPD and asthma pathologies of attention. The programs are characterized by an outpatient treatment with an average duration of eight to twelve weeks, with a frequency of an hour three times a week. Also, the director of the service is regularly a pulmonologist and the coordinator a physiotherapist (57.14%). The posgradual training of these professionals is notable, and they report to have procedural, administrative and communicative skills, but qualify regular there research skills. The physical and technological resources are well tested. 71.42% have done impact studies, but only 28.57% have been published. All have in common training in upper limbs, lower limbs, respiratory muscles, counseling, functional assessment and quality of life. The effectiveness and impact of programs is measured by the walking test, quality of life questionnaires and activities of daily living.

Estimation of electronic coupling in π -stacked donor-bridge-acceptor systems: correction of the two-state model

Comparison of donor-acceptor electronic couplings calculated within two-state and three-state models suggests that the two-state treatment can provide unreliable estimates of Vda because of neglecting the multistate effects. We show that in most cases accurate values of the electronic coupling in a π stack, where donor and acceptor are separated by a bridging unit, can be obtained as Ṽ da = (E2 - E1) μ12 Rda + (2 E3 - E1 - E2) 2 μ13 μ23 Rda2, where E1, E2, and E3 are adiabatic energies of the ground, charge-transfer, and bridge states, respectively, μij is the transition dipole moments between the states i and j, and Rda is the distance between the planes of donor and acceptor. In this expression based on the generalized Mulliken-Hush approach, the first term corresponds to the coupling derived within a two-state model, whereas the second term is the superexchange correction accounting for the bridge effect. The formula is extended to bridges consisting of several subunits. The influence of the donor-acceptor energy mismatch on the excess charge distribution, adiabatic dipole and transition moments, and electronic couplings is examined. A diagnostic is developed to determine whether the two-state approach can be applied. Based on numerical results, we showed that the superexchange correction considerably improves estimates of the donor-acceptor coupling derived within a two-state approach. In most cases when the two-state scheme fails, the formula gives reliable results which are in good agreement (within 5%) with the data of the three-state generalized Mulliken-Hush model

Multidisciplinary analysis of clinical cases: a transition towards active learning in dental education

In the past 2009/10 academic year, we took steps towards introduction of active methodologies, from a multidisciplinar approach, into a conventional lecture-based Dental Education program. We consolidated these practices in the current 2010/11 year, already within a new Bologna-adapted scheme. Transition involved (i) critical assessment of the limitations of traditional teaching (ii) identification of specific learning topics allowing for integration of contents, (iii) implementation of student-centred learning activities in old curricular plans (iv) assessment of students' satisfaction and perceived learning outcomes, (v) implementation of these changes in new Bologna-adapted curricula

Warranty cost analysis for products with a dormant state

Most building services products are installed while a building is constructed, but they are not operated until the building is commissioned. The warranty of the products may cover the time starting from their installation to the end of the warranty period. Prior to the commissioning of the building, the products are at a dormant mode (i.e., not operated) but protected by the warranty. For such products, both the usage intensity and the failure patterns are different from those with continuous usage intensity and failure patterns. This paper develops warranty cost models for repairable products with a dormant mode from both the manufacturer's and buyer's perspectives. Relationships between the failure patterns at the dormant mode and at the operational mode are also discussed. Numerical examples and sensitivity analysis are used to demonstrate the applicability of the methodology derived in the paper.