153 research outputs found
Model of the Quark Mixing Matrix
The structure of the Cabibbo-Kobayashi-Maskawa (CKM) matrix is analyzed from
the standpoint of a composite model. A model is constructed with three families
of quarks, by taking tensor products of sufficient numbers of spin-1/2
representations and imagining the dominant terms in the mass matrix to arise
from spin-spin interactions. Generic results then obtained include the familiar
relation , and a less frequently
seen relation . The magnitudes of
and come out naturally to be of the right order. The phase in
the CKM matrix can be put in by hand, but its origin remains obscure.Comment: Presented by Mihir P. Worah at DPF 92 Meeting, Fermilab, November,
1992. 3 pages, LaTeX fil
Hierarchical Quark Mass Matrices
I define a set of conditions that the most general hierarchical Yukawa mass
matrices have to satisfy so that the leading rotations in the diagonalization
matrix are a pair of (2,3) and (1,2) rotations. In addition to Fritzsch
structures, examples of such hierarchical structures include also matrices with
(1,3) elements of the same order or even much larger than the (1,2) elements.
Such matrices can be obtained in the framework of a flavor theory. To leading
order, the values of the angle in the (2,3) plane (s_{23}) and the angle in the
(1,2) plane (s_{12}) do not depend on the order in which they are taken when
diagonalizing. We find that any of the Cabbibo-Kobayashi-Maskawa matrix
parametrizations that consists of at least one (1,2) and one (2,3) rotation may
be suitable. In the particular case when the s_{13} diagonalization angles are
sufficiently small compared to the product s_{12}s_{23}, two special CKM
parametrizations emerge: the R_{12}R_{23}R_{12} parametrization follows with
s_{23} taken before the s_{12} rotation, and vice versa for the
R_{23}R_{12}R_{23} parametrization.Comment: LaTeX, 19 pages. References added, minor changes in text. Version
published in Phys. Rev.
An Extended Technicolor Model
An extended technicolor model is constructed. Quark and lepton masses,
spontaneous CP violation, and precision electroweak measurements are discussed.
Dynamical symmetry breaking is analyzed using the concept of the BIG MAC.Comment: 35 pages, Latex, YCTP-P21-93, BUHEP-93-2
The Effective Electroweak Chiral Lagrangian: The Matter Sector
We parametrize in a model-independent way possible departures from the
minimal Standard Model predictions in the matter sector. We only assume the
symmetry breaking pattern of the Standard Model and that new particles are
sufficiently heavy so that the symmetry is non-linearly realized. Models with
dynamical symmetry breaking are generically of this type. We review in the
effective theory language to what extent the simplest models of dynamical
breaking are actually constrained and the assumptions going into the comparison
with experiment. Dynamical symmetry breaking models can be approximated at
intermediate energies by four-fermion operators. We present a complete
classification of the latter when new particles appear in the usual
representations of the group as well as a partial
classification in the general case. We discuss the accuracy of the four-fermion
description by matching to a simple `fundamental' theory. The coefficients of
the effective lagrangian in the matter sector for dynamical symmetry breaking
models (expressed in terms of the coefficients of the four-quark operators) are
then compared to those of models with elementary scalars (such as the minimal
Standard Model). Contrary to a somewhat widespread belief, we see that the sign
of the vertex corrections is not fixed in dynamical symmetry breaking models.
This work provides the theoretical tools required to analyze, in a rather
general setting, constraints on the matter sector of the Standard Model.Comment: Latex, 45 pages, 8 eps figures. Sections 5, 6 and 9 have been
rewritten to clarify the contents. Some mistakes and typos have been
corrected. Two references have been added. Figures 7 and 8 have been modifie
Phase-plate electron microscopy: a novel imaging tool to reveal close-to-life nano-structures
After slow progress in the efforts to develop phase plates for electron microscopes, functional phase plate using thin carbon film has been reported recently. It permits collecting high-contrast images of close-to-life biological structures with cryo-fixation and without staining. This report reviews the state of the art for phase plates and what is innovated with them in biological electron microscopy. The extension of thin-film phase plates to the material-less type using electrostatic field or magnetic field is also addressed
Analysis of techni-dilaton as a dark matter candidate
The almost conformal dynamics of walking technicolor (TC) implies the
existence of the approximate scale invariance, which breaks down spontaneously
by the condensation of anti-techni and techni-fermions. According to the
Goldstone theorem, a spinless, parity-even particle, called techni-dilaton
(TD), then emerges at low energy. If TC exhibits an extreme walking, TD mass is
parametrically much smaller than that of techni-fermions (around 1 TeV), while
its decay constant is comparable to the cutoff scale of walking TC. We analyze
the light, decoupled TD as a dark matter candidate and study cosmological
productions of TD, both thermal and non-thermal, in the early Universe. The
thermal population is governed dominantly by single TD production processes
involving vertices breaking the scale symmetry, while the non-thermal
population is by the vacuum misalignment and is accumulated via harmonic and
coherent oscillations of misaligned classical TD fields. The non-thermal
population turns out to be dominant and large enough to explain the abundance
of presently observed dark matter, while the thermal population is highly
suppressed due to the large TD decay constant. Several cosmological and
astrophysical limits on the light, decoupled TD are examined to find that the
TD mass is constrained to be in a range between 0.01 eV and 500 eV. From the
combined constraints on cosmological productions and astrophysical
observations, we find that the light, decoupled TD can be a good dark matter
candidate with the mass around a few hundreds of eV for typical models of
(extreme) walking TC. We finally mention possible designated experiments to
detect the TD dark matter.Comment: 26 pages. 16 figures; v2, expanded Section 2.4 on composite Higgs in
light of newly discovered Higgs-like particle at LH
Permanent education in health: a review
OBJECTIVE : To undertake a meta-synthesis of the literature on the main concepts and practices related to permanent education in health. METHODS : A bibliographical search was conducted for original articles in the PubMed, Web of Science, LILACS, IBECS and SciELO databases, using the following search terms: “public health professional education”, “permanent education”, “continuing education”, “permanent education health”. Of the 590 articles identified, after applying inclusion and exclusion criteria, 48 were selected for further analysis, grouped according to the criteria of key elements, and then underwent meta-synthesis. RESULTS : The 48 original publications were classified according to four thematic units of key elements: 1) concepts, 2) strategies and difficulties, 3) public policies and 4) educational institutions. Three main conceptions of permanent education in health were found: problem-focused and team work, directly related to continuing education and education that takes place throughout life. The main strategies for executing permanent education in health are discussion, maintaining an open space for permanent education, and permanent education clusters. The most limiting factor is mainly related to directly or indirect management. Another highlight is the requirement for implementation and maintenance of public policies, and the availability of financial and human resources. The educational institutions need to combine education and service aiming to form critical-reflexive graduates. CONCLUSIONS : The coordination between health and education is based as much on the actions of health services as on management and educational institutions. Thus, it becomes a challenge to implement the teaching-learning processes that are supported by critical-reflexive actions. It is necessary to carry out proposals for permanent education in health involving the participation of health professionals, teachers and educational institutions.OBJETIVO : Realizar metasíntesis de la literatura sobre los principales conceptos y prácticas relacionados con la educación permanente en salud. MÉTODOS : Se realizó búsqueda bibliográfica de artículos originales en las bases de datos PubMed, Web of Science, Lilacs, IBECS y SciELO, utilizando los siguientes descriptores: “ public health professional education”, “permanent education”, “continuing education”, “permanent education health ”. De un total de 590 artículos identificados, posterior a los criterios de inclusión y exclusión, fueron seleccionados 48 para análisis, los cuales fueron sometidos al análisis individual, análisis comparativo, análisis con criterios de agrupamiento de elementos-clave y sometidos a metasíntesis. RESULTADOS : Los 48 artículos originales fueron clasificados como elementos-clave en cuatro unidades temáticas: 1) Concepciones; 2) Estrategias y dificultades; 3) Políticas públicas e 4) Instituciones formadoras. Se encontraron tres concepciones principales de educación permanente en salud: ubicación del problema y enfocarlo en el trabajo en equipo, directamente relacionado con la educación continua y educación que se da a lo largo de la vida. Las principales estrategias para efectivar la educación permanente fueron la ubicación del problema, mantenimiento de espacios para la educación permanente y polos de educación permanente. El mayor factor limitante estuvo relacionado con la gerencia directa o indirecta. Fueron mencionadas la necesidad de implementación y mantenimiento de políticas públicas, así como la disponibilidad de recursos financieros y humanos. Las instituciones formadoras tendrían la necesidad de articular educación y servicio para la formación de egresados críticos-reflexivos. CONCLUSIONES : La articulación educación y salud se encuentra pautada tanto en las acciones de los servicios de salud, cuanto en la gestión y de instituciones formadoras. Así, se torna un desafío implementar procesos de educación-aprendizaje que sean respaldados por acciones crítico-reflexivas. Es necesario realizar propuestas de educación permanente en salud con la participación de profesionales de los servicios, profesores y profesionales de las instituciones de educación.OBJETIVO : Realizar metassíntese da literatura sobre os principais conceitos e práticas relacionados à educação permanente em saúde. MÉTODOS : Foi realizada busca bibliográfica de artigos originais nas bases de dados PubMed, Web of Science, Lilacs, IBECS e SciELO, utilizando os seguintes descritores: “ public health professional education ”, “ permanent education”, “continuing education ”, “ permanent education health ”. De um total de 590 artigos identificados, após os critérios de inclusão e exclusão, foram selecionados 48 para análise, os quais foram submetidos à análise individual, análise comparativa, análise com critérios de agrupamentos de elementos-chave e submetidos à metassíntese. RESULTADOS : Os 48 artigos originais foram classificados como elementos-chave em quatro unidades temáticas: 1) Concepções; 2) Estratégias e dificuldades; 3) Políticas públicas; e 4) Instituições formadoras. Foram encontradas três concepções principais de educação permanente em saúde: problematizadora e focada no trabalho em equipe, diretamente relacionada à educação continuada e educação que se dá ao longo da vida. As principais estratégias para efetivação da educação permanente foram a problematização, manutenção de espaços para a educação permanente e polos de educação permanente. O maior fator limitante foi relacionado à gerência direta ou indireta. Foram indicadas a necessidade de implementação e manutenção de políticas públicas, além de disponibilidade de recursos financeiros e de recursos humanos. As instituições formadoras teriam necessidade de articular ensino e serviço para a formação de egressos críticos-reflexivos. CONCLUSÕES : A articulação educação e saúde encontra-se pautada tanto nas ações dos serviços de saúde, quanto de gestão e de instituições formadoras. Assim, torna-se um desafio implementar processos de ensino-aprendizagem que sejam respaldados por ações crítico-reflexivas. É necessário realizar propostas de educação permanente em saúde com a participação de profissionais dos serviços, professores e profissionais das instituições de ensino
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