Multiplicative local linear hazard estimation and best one-sided cross-validation

This paper develops detailed mathematical statistical theory of a new class of cross-validation techniques of local linear kernel hazards and their multiplicative bias corrections. The new class of cross-validation combines principles of local information and recent advances in indirect cross-validation. A few applications of cross-validating multiplicative kernel hazard estimation do exist in the literature. However, detailed mathematical statistical theory and small sample performance are introduced via this paper and further upgraded to our new class of best one-sided cross-validation. Best one-sided cross-validation turns out to have excellent performance in its practical illustrations, in its small sample performance and in its mathematical statistical theoretical performance

Phase Transition between the Cholesteric and Twist Grain Boundary C Phases

The upper critical temperature Tc2 for the phase transition between the Cholesteric phase (N*) and the Twist Grain Boundary C phase with the layer inclination tilted to the pitch axis (TGBct) in thermotropic liquid crystals is determined by the mean field Chen-Lubensky approach. We show that the N*-TGBct phase transition is split in two with the appearance of either the TGBA or the TGB2q phase in a narrow temperature interval below Tc2. The latter phase is novel in being superposed from two degenerate TGBct phases with different (left and right) layers inclinations to the pitch axis.Comment: Phys. Rev. E, to be publ; 24 pages, RevTeX + 3 ps figure

Analysis and Modification of Amorphous and Partially-Crystalline Thin Films

Thin films of light atomic weight elements in amorphous, partially-crystalline, or crystalline forms have applications in a broad range of technologies. For example, amorphous tetrahedral carbon (a-tC) and polymeric thin films impact electronic materials technology as electron- and light-emitting device elements, respectively. A lack of crystallinity introduces complexity in the experimental and theoretical characterization of these materials but is not necessarily a limiting factor in their performance. While the growth process is clearly a major factor governing the physical properties of a film, interactions with the substrate are also important, so surface and interface analysis provides an important complement to bulk measurements. This paper focuses on several approaches in the characterization and modification of thin films made possible by recent experimental advances. The structural and electronic properties of two model systems are considered as examples: a-tC thin films grown by pulsed laser deposition (PLD) and polyaniline thin films grown by vapor deposition. First, scanning probe microscopies and X-ray scattering are used to investigate the structural aspects of a-tC films as a function of PLD growth conditions. The possible connection of nanoscale surface modification and characterization with electron emission properties will be discussed. Second, the results of inelastic scattering spectroscopy and other surface techniques will be discussed to obtain information on both interfacial aspects of the growth of polyaniline thin films and microscopic and macroscopic aspects of electrical conductivity upon doping. Comparisons will be made with other studies that address properties of analogous crystalline systems as appropriate. A brief assessment of the broader problem of analyzing these systems will be given

Telemedicina: Situação em Portugal

Introdução: A telemedicina é hoje reconhecida pela OMS como uma ferramenta para melhorar o acesso e a qualidade dos cuidados de saúde. Apesar das vantagens aparentes é uma tecnologia recente e está longe de constituir uma prática de rotina na vida clínica diária. Objectivo: Conhecer a situação actual em Portugal relativamente à telemedicina, nomeadamente: quais as Unidades de Saúde com instalações de telemedicina e áreas em que se desenvolve esta actividade; número de serviços anuais e evolução; dificuldades e obstáculos dos profissionais e Instituições; perspectivas futuras Metodologia: A recolha dos dados foi efectuado através de: inquérito enviados às ARS do Norte, Centro, Lisboa e Vale do Tejo, Alentejo, Algarve e IGIF; entrevista com algumas instituições relativa aos serviços em funcionamento; pesquisa bibliográfica e na Internet Resultados: Dos 6 inquéritos enviados foram recebidos 5, provenientes da ARS Norte, Centro, Lisboa e Vale do Tejo, Algarve e Alentejo. Foram efectuadas entrevistas: H S. João, CHVila Nova de Gaia, CHVale do Sousa e H Pediátrico de Coimbra. Obtivemos informações relativas aos equipamentos instalados e serviços actualmente em funcionamento, em todo o país, destacando- se o funcionamento nas áreas da cardiologia, imagiologia e dermatologia. Não havia registo do número de teleconsultas e transmissão de exames excepto no que se refere à ARS Alentejo. Das dificuldades e obstáculos encontrados salientamos a falta de adesão dos profissionais e instituições; custos do funcionamento do sistema; ausência de definição funcional dos profissionais envolvidos (falta de remuneração dos actos médicos e acumulação de funções); ausência de uma estratégia nacional. Quanto às perspectivas futuras, de um modo geral, os objectivos das ARS incluem: a ligação dos centros de saúde e hospitais, e petrechamento com um equipamento básico de Telemedicina em conformidade com as actividades e tipos de consulta a realizar; o desenvolvimento de projectos no âmbito do INTERREG III. Comentários: O desafio que as organizações tem que enfrentar é a mudança estrutural provocada pela modernização dos processos e métodos de trabalho, «o hospital virtual», e a diluição das barreiras entre os Cuidados Primários e os Diferenciados. A telemedicina exige novas formas de gestão e de medição de desempenho das instituições; esta actividade deve ser equiparada às outras normalmente desenvolvidas nas unidades de saúde. Introduction: Telemedicine is recognized by the WHO as a tool for improvement of access and the quality of health care. However it is not yet a routine procedure in health services. Objective: to assess the utilization of telemedicine in Portugal, namely: health care services equipped with telemedicine, and services provided; annual services and evolution; difficulties and obstacles from professionals and institutions; future trends Methodology: data was obtained through a questionnaire sent to the five Regional Administrations of Health and the Financial Department of Health, interviews with some of the professionals practising Telemedicine and research in the web Results: We received five questionnaires from the Regional Administrations of Health, and collected data from the following Hospitals: S. João, Vila Nova de Gaia, Vale do Sousa e Coimbra Children’s Hospital. We obtained information of the institutions practising telemedicine, and the type of services. Cardiology, radiology and dermatology were the services more frequently provided. The number of teleconsultations or transmitted studies was not registered, except in Alentejo. The more common difficulties to implement this technology were: clinical and providers acceptance; lack of integration into the health care mainstream (the costs of teleconsultations are not reimbursed); equipment and operational costs; absence of a national strategy. Future trends include the equipment of telemedicine stations in Primary and Hospital care and the development of projects in cooperation with Spain (INTERREG III). Comments: Organizations face the challenge of a structural change due to the new technologies (telemedicine and health informatics) and the disappearance of barriers between primary and hospital care. Institutional, organizational and national policies must face new realities to introduce telemedicine into the mainstream of health, including assessment of health outcomes

Telemedicina: Situação em Portugal

Introdução: A telemedicina é hoje reconhecida pela OMS como uma ferramenta para melhorar o acesso e a qualidade dos cuidados de saúde. Apesar das vantagens aparentes é uma tecnologia recente e está longe de constituir uma prática de rotina na vida clínica diária. Objectivo: Conhecer a situação actual em Portugal relativamente à telemedicina, nomeadamente: quais as Unidades de Saúde com instalações de telemedicina e áreas em que se desenvolve esta actividade; número de serviços anuais e evolução; dificuldades e obstáculos dos profissionais e Instituições; perspectivas futuras Metodologia: A recolha dos dados foi efectuado através de: inquérito enviados às ARS do Norte, Centro, Lisboa e Vale do Tejo, Alentejo, Algarve e IGIF; entrevista com algumas instituições relativa aos serviços em funcionamento; pesquisa bibliográfica e na Internet Resultados: Dos 6 inquéritos enviados foram recebidos 5, provenientes da ARS Norte, Centro, Lisboa e Vale do Tejo, Algarve e Alentejo. Foram efectuadas entrevistas: H S. João, CHVila Nova de Gaia, CHVale do Sousa e H Pediátrico de Coimbra. Obtivemos informações relativas aos equipamentos instalados e serviços actualmente em funcionamento, em todo o país, destacando- se o funcionamento nas áreas da cardiologia, imagiologia e dermatologia. Não havia registo do número de teleconsultas e transmissão de exames excepto no que se refere à ARS Alentejo. Das dificuldades e obstáculos encontrados salientamos a falta de adesão dos profissionais e instituições; custos do funcionamento do sistema; ausência de definição funcional dos profissionais envolvidos (falta de remuneração dos actos médicos e acumulação de funções); ausência de uma estratégia nacional. Quanto às perspectivas futuras, de um modo geral, os objectivos das ARS incluem: a ligação dos centros de saúde e hospitais, e petrechamento com um equipamento básico de Telemedicina em conformidade com as actividades e tipos de consulta a realizar; o desenvolvimento de projectos no âmbito do INTERREG III. Comentários: O desafio que as organizações tem que enfrentar é a mudança estrutural provocada pela modernização dos processos e métodos de trabalho, «o hospital virtual», e a diluição das barreiras entre os Cuidados Primários e os Diferenciados. A telemedicina exige novas formas de gestão e de medição de desempenho das instituições; esta actividade deve ser equiparada às outras normalmente desenvolvidas nas unidades de saúde. Introduction: Telemedicine is recognized by the WHO as a tool for improvement of access and the quality of health care. However it is not yet a routine procedure in health services. Objective: to assess the utilization of telemedicine in Portugal, namely: health care services equipped with telemedicine, and services provided; annual services and evolution; difficulties and obstacles from professionals and institutions; future trends Methodology: data was obtained through a questionnaire sent to the five Regional Administrations of Health and the Financial Department of Health, interviews with some of the professionals practising Telemedicine and research in the web Results: We received five questionnaires from the Regional Administrations of Health, and collected data from the following Hospitals: S. João, Vila Nova de Gaia, Vale do Sousa e Coimbra Children’s Hospital. We obtained information of the institutions practising telemedicine, and the type of services. Cardiology, radiology and dermatology were the services more frequently provided. The number of teleconsultations or transmitted studies was not registered, except in Alentejo. The more common difficulties to implement this technology were: clinical and providers acceptance; lack of integration into the health care mainstream (the costs of teleconsultations are not reimbursed); equipment and operational costs; absence of a national strategy. Future trends include the equipment of telemedicine stations in Primary and Hospital care and the development of projects in cooperation with Spain (INTERREG III). Comments: Organizations face the challenge of a structural change due to the new technologies (telemedicine and health informatics) and the disappearance of barriers between primary and hospital care. Institutional, organizational and national policies must face new realities to introduce telemedicine into the mainstream of health, including assessment of health outcomes

Charge-Carrier Dynamics in 2D Hybrid Metal–Halide Perovskites

Hybrid metal–halide perovskites are promising new materials for use in solar cells; however, their chemical stability in the presence of moisture remains a significant drawback. Quasi two-dimensional (2D) perovskites that incorporate hydrophobic organic interlayers offer improved resistance to degradation by moisture, currently still at the cost of overall cell efficiency. To elucidate the factors affecting the optoelectronic properties of these materials, we have investigated the charge transport properties and crystallographic orientation of mixed methylammonium (MA)–phenylethylammonium (PEA) lead iodide thin films as a function of the MA-to-PEA ratio and, thus, the thickness of the “encapsulated” MA lead–halide layers. We find that monomolecular charge-carrier recombination rates first decrease with increasing PEA fraction, most likely as a result of trap passivation, but then increase significantly as excitonic effects begin to dominate for thin confined layers. Bimolecular and Auger recombination rate constants are found to be sensitive to changes in electronic confinement, which alters the density of states for electronic transitions. We demonstrate that effective charge-carrier mobilities remain remarkably high (near 10 cm2V−1s−1) for intermediate PEA content and are enhanced for preferential orientation of the conducting lead iodide layers along the probing electric field. The trade-off between trap reduction, electronic confinement, and layer orientation leads to calculated charge-carrier diffusion lengths reaching a maximum of 2.5 μm for intermediate PEA content (50%)

High-resolution x-ray study of the nematic - smectic-A and smectic-A - smectic-C transitions in 8barS5-aerosil gels

The effects of dispersed aerosil nanoparticles on two of the phase transitions of the thermotropic liquid crystal material 4-n-pentylphenylthiol-4'-n-octyloxybenzoate 8barS5 have been studied using high-resolution x-ray diffraction techniques. The aerosils hydrogen bond together to form a gel which imposes a weak quenched disorder on the liquid crystal. The smectic-A fluctuations are well characterized by a two-component line shape representing thermal and random-field contributions. An elaboration on this line shape is required to describe the fluctuations in the smectic-C phase; specifically the effect of the tilt on the wave-vector dependence of the thermal fluctuations must be explicitly taken into account. Both the magnitude and the temperature dependence of the smectic-C tilt order parameter are observed to be unaffected by the disorder. This may be a consequence of the large bare smectic correlation length in the direction of modulation for this transition. These results show that the understanding developed for the nematic to smectic-A transition for octylcyanobiphenyl (8CB) and octyloxycyanobiphenyl (8OCB) liquid crystals with quenched disorder can be extended to quite different materials and transitions.Comment: 7 pages, 8 figure