Growth and characterization of novel, III-V semiconductor heterostructures

The material presented in this thesis concerns the growth and characterization of III-V semiconductor heterostructures. Studies of the interactions between bound states in coupled quantum wells and between well and barrier bound states in AlAs/GaAs heterostructures are presented. We also demonstrate the broad array of novel tunnel structures realizable in the InAs/GaSb/AlSb material system. Because of the unique broken-gap band alignment of InAs/GaSb these structures involve transport between the conduction- and valence-bands of adjacent layers. These devices possess a wide range of electrical properties and are fundamentally different from conventional AlAs/GaAs tunnel devices. We report on the fabrication of a novel tunnel transistor with the largest reported room temperature current gains. We also present time-resolved studies of the growth fronts of InAs/GainSb strained layer superlattices and investigations of surface anion exchange reactions.

Chapter 2 covers tunneling studies of conventional AlAs/GaAs RTD's. The results of two studies are presented: (i) A test of coherent vs. sequential tunneling in triple barrier heterostructures, (ii) An optical measurement of the effect of barrier X-point states on Γ-point well states. In the first it was found if two quantum wells are separated by a sufficiently thin barrier, then the eigenstates of the system extend coherently across both wells and the central barriers. For thicker barriers between the wells, the electrons become localized in the individual wells and transport is best described by the electrons hopping between the wells. In the second, it was found that Γ-point well states and X-point barrier states interact strongly. The barrier X-point states modify the energies of the well states and increase the escape rate for carriers in the quantum well.

The results of several experimental studies of a novel class of tunnel devices realized in the InAs/GaSb/AlSb material system are presented in Chapter 3. These interband tunnel structures involve transport between conduction- and valence-band states in adjacent material layers. These devices are compared and contrasted with the conventional AlAs/GaAs structures discussed in Chapter 2 and experimental results are presented for both resonant and nonresonant devices. These results are compared with theoretical simulations and necessary extensions to the theoretical models are discussed.

In chapter 4 experimental results from a novel tunnel transistor are reported. The measured current gains in this transistor exceed 100 at room temperature. This is the highest reported gain at room temperature for any tunnel transistor. The device is analyzed and the current conduction and gain mechanisms are discussed.

Chapters 5 and 6 are studies of the growth of structures involving layers with different anions. Chapter 5 covers the growth of InAs/GainSb superlattices for far infrared detectors and time resolved, in-situ studies of their growth fronts. It was found that the bandgap of superlattices with identical layer thicknesses and compositions varied by as much as 40 meV depending on how their internal interfaces are formed. The absorption lengths in superlattices with identical bandgaps but whose interfaces were formed in different ways varied by as much as a factor of two. First the superlattice is discussed including an explanation of the device and the complications involved in its growth. The experimental technique of reflection high energy electron diffraction (RHEED) is reviewed, and the results of RHEED studies of the growth of these complicated structures are presented. The development of a time resolved, in-situ characterization of the internal interfaces of these superlattices is described. Chapter 6 describes the result of a detailed study of some of the phenomena described in chapter 5. X-ray photoelectron spectroscopy (XPS) studies of anion exchange reactions on the growth fronts of these superlattices are reported. Concurrent RHEED studies of the same physical systems studied with XPS are presented. Using the RHEED and XPS results, a real-time, indirect measurement of surface exchange reactions was developed.

Enhanced dispersive wave generation by using chirped pulses in a microstructured fiber

A theoretical investigation on the nonlinear pulse propagation and dispersive wave generation in the anomalous dispersion region of a microstructured fiber is presented. By simulating the dispersive wave generation under different conditions. it is found that the generation mechanism of the dispersive wave is mainly due to the pulse trapping across the zero-dispersion wavelength. By varying the initial pulse chirp, the output spectrum can be broadened and the intensity of the dispersive wave can be obviously enhanced. In particular, there exists an optimal positive chirp which maximizes the intensity of the dispersive wave. This effect can be explained by the energy transfer from the Raman soliton to the dispersive wave due to the effect of the pulse trapping and the effect of the higher-order dispersion. From the phase aspect, the explanation of this effect is also included. (C) 2004 Elsevier B.V. All rights reserved.

An examination of strategic opportunities provided by the conference committee procedure in the U.S. Congress

Deference to committees in Congress has been a much studied phenomena for close to 100 years. This deference can be characterized as the unwillingness of a potentially winning coalition on the House floor to impose its will on a small minority, a standing committee. The congressional scholar is then faced with two problems: observing such deference to committees, and explaining it. Shepsle and Weingast have proposed the existence of an ex-post veto for standing committees as an explanation of committee deference. They claim that as conference reports in the House and Senate are considered under a rule that does not allow amendments, the conferees enjoy agenda-setting power. In this paper I describe a test of such a hypothesis (along with competing hypotheses regarding the effects of the conference procedure). A random-utility model is utilized to estimate legislators' ideal points on appropriations bills from 1973 through 1980. I prove two things: 1) that committee deference can not be said to be a result of the conference procedure; and moreover 2) that committee deference does not appear to exist at all.

Geological evolution of two crustal scale shear zones. Part I. The Rand thrust complex, northwestern Mojave Desert, California. Part II. The Magdalena metamorphic core complex, north central Sonora, Mexico

The geology and structure of two crustal scale shear zones were studied to understand the partitioning of strain within intracontinental orogenic belts. Movement histories and regional tectonic implications are deduced from observational data. The two widely separated study areas bear the imprint of intense Late Mesozoic through Middle Cenozoic tectonic activity. A regional transition from Late Cretaceous-Early Tertiary plutonism, metamorphism, and shortening strain to Middle Tertiary extension and magmatism is preserved in each area, with contrasting environments and mechanisms. Compressional phases of this tectonic history are better displayed in the Rand Mountains, whereas younger extensional structures dominate rock fabrics in the Magdalena area.

In the northwestern Mojave desert, the Rand Thrust Complex reveals a stack of four distinctive tectonic plates offset along the Garlock Fault. The lowermost plate, Rand Schist, is composed of greenschist facies metagraywacke, metachert, and metabasalt. Rand Schist is structurally overlain by Johannesburg Gneiss (= garnet-amphibolite grade orthogneisses, marbles and quartzites), which in turn is overlain by a Late Cretaceous hornblende-biotite granodiorite. Biotite granite forms the fourth and highest plate. Initial assembly of the tectonic stack involved a Late Cretaceous? south or southwest vergent overthrusting event in which Johannesburg Gneiss was imbricated and attenuated between Rand Schist and hornblende-biotite granodiorite. Thrusting postdated metamorphism and deformation of the lower two plates in separate environments. A post-kinematic stock, the Late Cretaceous Randsburg Granodiorite, intrudes deep levels of the complex and contains xenoliths of both Rand Schist and mylonitized Johannesburg? gneiss. Minimum shortening implied by the map patterns is 20 kilometers.

Some low angle faults of the Rand Thrust Complex formed or were reactivated between Late Cretaceous and Early Miocene time. South-southwest directed mylonites derived from Johannesburg Gneiss are commonly overprinted by less penetrative north-northeast vergent structures. Available kinematic information at shallower structural levels indicates that late disturbance(s) culminated in northward transport of the uppermost plate. Persistence of brittle fabrics along certain structural horizons suggests a possible association of late movement(s) with regionally known detachment faults. The four plates were juxtaposed and significant intraplate movements had ceased prior to Early Miocene emplacement of rhyolite porphyry dikes.

In the Magdalena region of north central Sonora, components of a pre-Middle Cretaceous stratigraphy are used as strain markers in tracking the evolution of a long lived orogenic belt. Important elements of the tectonic history include: (1) Compression during the Late Cretaceous and Early Tertiary, accompanied by plutonism, metamorphism, and ductile strain at depth, and thrust driven? syntectonic sedimentation at the surface. (2) Middle Tertiary transition to crustal extension, initially recorded by intrusion of leucogranites, inflation of the previously shortened middle and upper crustal section, and surface volcanism. (3) Gravity induced development of a normal sense ductile shear zone at mid crustal levels, with eventual detachment and southwestward displacement of the upper crustal stratigraphy by Early Miocene time.

Elucidation of the metamorphic core complex evolution just described was facilitated by fortuitous preservation of a unique assemblage of rocks and structures. The "type" stratigraphy utilized for regional correlation and strain analysis includes a Jurassic volcanic arc assemblage overlain by an Upper Jurassic-Lower Cretaceous quartz pebble conglomerate, in turn overlain by marine strata with fossiliferous Aptian-Albian limestones. The Jurassic strata, comprised of (a) rhyolite porphyries interstratified with quartz arenites, (b) rhyolite cobble conglomerate, and (c) intrusive granite porphyries, are known to rest on Precambrian basement north and east of the study area. The quartz pebble conglomerate is correlated with the Glance Conglomerate of southeastern Arizona and northeastern Sonora. The marine sequence represents part of an isolated arm? of the Bisbee Basin.

Crosscutting structural relationships between the pre-Middle Cretaceous supracrustal section, younger plutons, and deformational fabrics allow the tectonic sequence to be determined. Earliest phases of a Late Cretaceous-Early Tertiary orogeny are marked by emplacement of the 78 ± 3 Ma Guacomea Granodiorite (U/Pb zircon, Anderson et al., 1980) as a sill into deep levels of the layered Jurassic series. Subsequent regional metamorphism and ductile strain is recorded by a penetrative schistosity and lineation, and east-west trending folds. These fabrics are intruded by post-kinematic Early Tertiary? two mica granites. At shallower crustal levels, the orogeny is represented by north directed thrust faulting, formation of a large intermontane basin, and development of a pronounced unconformity. A second important phase of ductile strain followed Middle Tertiary? emplacement of leucogranites as sills and northwest trending dikes into intermediate levels of the deformed section (surficial volcanism was also active during this transitional period to regional extension). Gravitational instabilities resulting from crustal swelling via intrusion and thermal expansion led to development of a ductile shear zone within the stratigraphic horizon occupied by a laterally extensive leucogranite sill. With continued extension, upper crustal brittle normal faults (detachment faults) enhanced the uplift and tectonic denudation of this mylonite zone, ultimately resulting in southwestward displacement of the upper crustal stratigraphy.

Strains associated with the two ductile deformation events have been successfully partitioned through a multifaceted analysis. R_f/Ø measurements on various markers from the "type" stratigraphy allow a gradient representing cumulative strain since Middle Cretaceous time to be determined. From this gradient, noncoaxial strains accrued since emplacement of the leucogranites may be removed. Irrotational components of the postleucogranite strain are measured from quartz grain shapes in deformed granites; rotational components (shear strains) are determined from S-C fabrics and from restoration of rotated dike and vein networks. Structural observations and strain data are compatable with a deformation path of: (1) coaxial strain (pure shear?), followed by (2) injection of leucogranites as dikes (perpendicular to the minimum principle stress) and sills (parallel to the minimum principle stress), then (3) southwest directed simple shear. Modeling the late strain gradient as a simple shear zone permits a minimum displacement of 10 kilometers on the Magdalena mylonite zone/detachment fault system. Removal of the Middle Tertiary noncoaxial strains yields a residual (or pre-existing) strain gradient representative of the Late Cretaceous-Early Tertiary deformation. Several partially destrained cross sections, restored to the time of leucogranite emplacement, illustrate the idea that the upper plate of the core complex bas been detached from a region of significant topographic relief. 50% to 100% bulk extension across a 50 kilometer wide corridor is demonstrated.

Late Cenozoic tectonics of the Magdalena region are dominated by Basin and Range style faulting. Northeast and north-northwest trending high angle normal faults have interacted to extend the crust in an east-west direction. Net extension for this period is minor (10% to 15%) in comparison to the Middle Tertiary detachment related extensional episode.

消色差相位匹配在光参量啁啾脉冲放大中的应用

Optical parametric chirped-pulse amplification (OPCPA) supplies broadband gain for ultrashort pulses. A new theoretic explanation of OPCPA has been obtained by introducing the concept of tilted pulse front in this paper, and the distribution of broadband amplification has been twice expanded by introducing the technology of achromatic phase matching (APM). The prospect of APM in OPCPA has been discussed in detail. Finally, a design for the amplification of chirped pulses at 1600 nm has been firstly proposed and numerically simulated. (C) 2004 Elsevier B.V. All rights reserved.

Charge displacement in ultraintense laser-plasma interaction

The distribution of optical held and charge density in the interaction between ultraintense ultrashort pulse laser and plasma is studied by numerical computation. The plasma considered has an exponential density profile. which corresponds to isothermal expanding. Our calculation shows that electrons are pushed forward by the incident laser, but ions, due to their much greater inertia, remain stationary. The resulting charge displacement forms a strong electrostatic field in the plasma. After the interaction of laser pulse and plasma. electrostatic energy still exists even after the laser pulse and will be absorbed by the plasma finally. This serves as an explanation to the mechanism of laser energy deposited into plasma.

Model studies of Ziegler-Natta olefin polymerization using group 3 and group 4 metallocenes

Evidence for the stereochemical isomerization of a variety of ansa metallocene compounds is presented. For the scandocene allyl derivatives described here, we have established that the process is promoted by a variety of salts in both ether and hydrocarbon solvents and is not accelerated by light. A plausible mechanism based on an earlier proposal by Marks, et al., is offered as an explanation of this process. It involves coordination of anions and/or donor solvents to the metal center with cation assistance to encourage metalcyclopentadienyl bond heterolysis, rotation about the Si-Cp bond of the detached cyclopentadienide and recoordination of the opposite face. Our observations in some cases of thermodynamic racemic:meso ratios under the reaction conditions commonly used for the synthesis of the metallocene chlorides suggests that the interchange is faster than metallation, such that the composition of the reaction mixture is determined by thermodynamic, not kinetic, control in these cases.

Two new ansa-scandocene alkenyl compounds react with olefins resulting in the formation of η³-allyl complexes. Kinetics and labeling experiments indicate a tuck-in intermediate on the reaction pathway; in this intermediate the metal is bound to the carbon adjacent to the silyllinker in the rear of the metallocene wedge. In contrast, reaction of permethylscandocene alkenyl compounds with olefins results, almost exclusively, in vinylic C-H bond activation. It is proposed that relieving transition state steric interactions between the cyclopentadienyl rings and the olefin by either linking the rings together or using a larger lanthanide metal may allow for olefin coordination, stabilizing the transition state for allylic σ-bond metathesis.

A selectively isotopically labeled propylene, CH₂CD(¹³CH₃), was synthesized and its polymerization was carried out at low concentration in toluene solution using isospecific metallocene catalysts. Analysis of the NMR spectra (¹³C, ¹H, and ²H) of the resultant polymers revealed that the production of stereoerrors through chain epimerization proceeds exclusively by the tertiaryalkyl mechanism. Additionally, enantiofacial inversion of the terminally unsaturated polymer chain occurs by a non-dissociative process. The implications of these results on the mechanism of olefin polymerization with these catalysts is discussed.

Baryon number violation beyond the standard model

This thesis describes simple extensions of the standard model with new sources of baryon number violation but no proton decay. The motivation for constructing such theories comes from the shortcomings of the standard model to explain the generation of baryon asymmetry in the universe, and from the absence of experimental evidence for proton decay. However, lack of any direct evidence for baryon number violation in general puts strong bounds on the naturalness of some of those models and favors theories with suppressed baryon number violation below the TeV scale. The initial part of the thesis concentrates on investigating models containing new scalars responsible for baryon number breaking. A model with new color sextet scalars is analyzed in more detail. Apart from generating cosmological baryon number, it gives nontrivial predictions for the neutron-antineutron oscillations, the electric dipole moment of the neutron, and neutral meson mixing. The second model discussed in the thesis contains a new scalar leptoquark. Although this model predicts mainly lepton flavor violation and a nonzero electric dipole moment of the electron, it includes, in its original form, baryon number violating nonrenormalizable dimension-five operators triggering proton decay. Imposing an appropriate discrete symmetry forbids such operators. Finally, a supersymmetric model with gauged baryon and lepton numbers is proposed. It provides a natural explanation for proton stability and predicts lepton number violating processes below the supersymmetry breaking scale, which can be tested at the Large Hadron Collider. The dark matter candidate in this model carries baryon number and can be searched for in direct detection experiments as well. The thesis is completed by constructing and briefly discussing a minimal extension of the standard model with gauged baryon, lepton, and flavor symmetries.

Extractive institutions in colonial Africa

A common explanation for African current underdevelopment is the extractive character of institutions established during the colonial period. Yet, since colonial extraction is hard to quantify and its exact mechanisms are not well understood, we still do not know precisely how colonial institutions affect economic growth today. In this project, I study this issue by focusing on the peculiar structure of trade and labor policies employed by the French colonizers.

First, I analyze how trade monopsonies and coercive labor institutions reduced African gains from trade during the colonial period. By using new data on prices to agricultural producers and labor institutions in French Africa, I show that (1) the monopsonistic character of colonial trade implied a reduction in prices to producers far below world market prices; (2) coercive labor institutions allowed the colonizers to reduce prices even further; (3) as a consequence, colonial extraction cut African gains from trade by over 60%.

Given the importance of labor institutions, I then focus on their origin by analyzing the colonial governments' incentives to choose between coerced and free labor. I argue that the choice of institutions was affected more by the properties of exported commodities, such as prices and economies of scale, than by the characteristics of colonies, such indigenous population density and ease of settlement for the colonizers.

Finally, I study the long-term effects of colonial trade monopsonies and coercive labor institutions. By combining archival data on prices in the French colonies with maps of crop suitability, I show that the extent to which prices to agricultural producers were reduced with respect to world market prices is strongly negatively correlated with current regional development, as proxied by luminosity data from satellite images. The evidence suggests that colonial extraction affected subsequent growth by reducing development in rural areas in favor of a urban elite. The differential impact in rural and urban areas can be the reason why trade monopsonies and extractive institutions persisted long after independence.

Causalidade psíquica em Freud

O objetivo da dissertação é abordar a teoria causal do mental de Freud e seu uso na explicação do conflito psíquico. É destacada a dupla dimensão da causalidade psíquica freudiana que oscila de uma causalidade mecanicista a uma causalidade intencional. Considera-se que a forma mais coerente de defender a tese da causalidade psíquica é descrevê-la como intencional, usando o vocabulário psicológico. Para dar suporte a essa idéia, a concepção estrita da causalidade sustentada por Wittgenstein é dispensada, e a idéia de causa mental em Davidson é endossada como aquela que pode ser mais facilmente articulável às hipóteses freudianas. A questão é analisada em três momentos da obra freudiana. Na primeira tópica, Freud usa um vocabulário híbrido, descrevendo o psiquismo tanto em termos de causa racionais quanto em termos de causas intencionais. Na segunda tópica, o psiquismo assume, cada vez mais, uma descrição intencional, e a causa a-racional da energia pulsional, inicialmente apresentada como um motor do psiquismo, dá um lugar a angústia como um afeto intencional que obriga o eu a encontrar uma solução para os conflitos psíquicos.

As práticas de saúde do enfermeiro e do agente comunitário de saúde na visita domiciliar da Estratégia Saúde da Família

Esta pesquisa teve como objetivo conhecer os sentidos atribuídos pelos enfermeiros e agentes comunitários de saúde da Estratégia Saúde da Família do município do Rio de Janeiro/RJ acerca das práticas de saúde desenvolvidas na visita domiciliar. É um estudo descritivo, de natureza qualitativa e teve como abordagem metodológica a hermenêutica-dialética. O cenário foi a cidade do Rio de Janeiro/RJ, em duas Unidades Básicas de Saúde da Família (UBSF) da Área Programática 3.1. Os sujeitos foram 08 enfermeiros e 07 agentes comunitários de saúde (ACSs) atuantes nas UBSF selecionadas. A coleta de dados foi realizada entre janeiro e março de 2010, por meio de entrevistas semi-estruturadas e para a avaliação dos resultados utilizou-se a técnica de análise de conteúdo proposta por Bardin. A partir dos resultados alcançados foi possível elaborar três categorias de estudo: a primeira trata das práticas de saúde do enfermeiro e do ACS na Estratégia Saúde da Família (ESF); a segunda aborda a visita domiciliar do enfermeiro e do ACS, a qual inclui subcategorias sobre o trabalho em equipe na visita domiciliar, as dificuldades na realização da visita domiciliar, o planejamento da visita domiciliar, o vínculo entre enfermeiro, ACS e família na visita domiciliar e a interação profissional do enfermeiro e do ACS na visita domiciliar; a última categoria trata dos sentidos atribuídos pelos enfermeiros e ACSs acerca das práticas de saúde desenvolvidas na visita domiciliar, as quais incluem subcategorias sobre as práticas de saúde do enfermeiro e do ACS na visita domiciliar e as opiniões sobre a visita domiciliar. Com a análise dos dados constatou-se que os enfermeiros e os ACS's desenvolvem diversas práticas de saúde na ESF, com destaque para as práticas de cuidado. As práticas de cuidado do enfermeiro na visita domiciliar estão voltadas para a investigação das necessidades de saúde e realização das atividades assistenciais. Já as do ACS estão voltadas para a identificação de demandas. A escuta ativa, a observação da estrutura física, da alimentação e das relações familiares e a educação em saúde são as principais práticas de cuidado realizadas em conjunto por estes profissionais na visita domiciliar. O percentual de visitas domiciliares semanais do enfermeiro está abaixo do esperado, sendo que a principal justificativa para este baixo índice é a sobrecarga de trabalho na UBSF. Ficou evidente que a interação profissional entre enfermeiro e ACS na visita domiciliar é pequena, pois diversas vezes, o ACS está presente na visita domiciliar do enfermeiro apenas como acompanhante. Por fim, pode-se constatar que o cuidado desenvolvido por enfermeiros e por ACSs é distinto. A prática de cuidado que o enfermeiro desenvolve na visita domiciliar é específica, destinada às famílias com prioridades de saúde e a que o ACS desenvolve é mais ampla, voltada para todas as famílias da microárea. Estas conclusões demonstram a necessidade de estimular enfermeiros e ACSs a (re)pensarem as práticas de saúde desenvolvidas na visita domiciliar, bem como a compreenderem e discutirem seus papéis e a interação nesta atividade.

Da genialidade sensível ao amor à norma: existência e consciência em Kierkegaard

Essa dissertação pretende deter-se sobre três pequenos e específicos textos constantes da obra Ou... Ou, do dinamarquês Sören Aybe Kierkegaard (1813-1855). Os dois primeiros textos são Os estados eróticos imediatos e Diário do Sedutor, e estão entre os textos da primeira parte do livro supracitado; o terceiro texto intitula-se O equilíbrio entre o estético e o ético na formação da personalidade e pertence à segunda parte do mesmo livro. Partindo de uma explicitação detalhada do conteúdo destes textos pretende-se pensar a questão dos estádios kierkegaardianos (estético, ético e religioso) e a forma como estes se relacionam com a existência e a consciência. No âmbito da existência concreta, a questão da consciência aparece para o filósofo dinamarquês a partir da explanação destas três dimensões existenciais, as quais se constituem em sintonia com disposições afetivas e também com modos materiais de viver e agir, detidamente descritos pela existência cotidiana de personagens. Desprovida, inicialmente, de qualquer determinação, a consciência vai se concretizando a partir de sua existência sensível, que guarda constantemente diferentes momentos ou possibilidades próprias. A tese fundamental a ser discutida, neste contexto, é a de que esses momentos existenciais não podem ser considerados de forma evolutiva, mas precisam ser tomados como possibilidades ou formas de vida, com sua positividade e seus riscos. O trabalho pretende mostrar de que forma as leituras correntes da filosofia de Kierkegaard tendem a enaltecer o aspecto ético e moral dos estádios, acabando por ignorar a dimensão mais originária do ser, qual seja, a dimensão da disposição imediata que, ao ser desprezada, abre um flanco entre o homem e ele mesmo.

A Responsabilidade Civil do Advogado sob a perspectiva civil-constitucional

A responsabilidade civil do advogado é um tema que merece destaque sob a perspectiva civil constitucional. A abrangência dessa relação jurídica pelo Código de Defesa do Consumidor e a natureza negocial multiforme da relação estabelecida entre o advogado e o cliente, cuja normativa deve ser estabecida tendo em vista o caso concreto, são pontos de destaque desse trabalho, assim como a aplicabilidade do consentimento informado. Nessa toada, pretende-se conferir o enfoque funcional a partir da releitura das classificações tradicionais da responsabilidade civil em contratual, extracontratual, subjetiva, objetiva e entre as obrigações de meio e resultado para em seguida, analisarmos das hipóteses mais frequentes de responsabilização, quais sejam: a perda de uma chance, o abuso do direito processual e a reversão de liminares revertidas ao final do processo. Por fim, dentre as tendências de prevenção e precaução de danos da responsabilidade civil, revela-se a formalização de seguros de responsabilidade profissional para advogados.

A pessoa estomizada e o processo de inclusão no trabalho: contribuição para a enfermagem

Estudo cujo objeto tratou da inclusão do cliente estomizado no mundo do trabalho. Os objetivos foram: identificar as dificuldades e facilidades dos clientes estomizados para inclusão no mundo do trabalho; analisar as possibilidades de inclusão no mundo do trabalho; discutir, a partir do ponto de vista do cliente estomizado, as orientações fornecidas pelos enfermeiros com vistas à inclusão no mundo do trabalho. O referencial teórico baseou-se no campo da Saúde do Trabalhador, enfocando a reabilitação profissional e o capítulo de bases conceituais abordou o conhecimento da estomaterapia, do mundo do trabalho, da deficiência física e aspectos legais que envolvem a reabilitação do estomizado no mundo laboral. O desenho metodológico foi de uma pesquisa descritiva, exploratória, de natureza qualitativa, realizada com 20 clientes estomizados definitivos, aos quais se aplicou uma entrevista semiestruturada. O método de análise dos dados foi a Análise Temática de Conteúdo, a qual fez emergir quatro categorias: a) Sentidos do Trabalho para o Ser Estomizado; b) O Estomizado e Sua Problemática Biopsicossocial; c) Contexto Social e Aspectos Legais Envolvendo a Inclusão do Estomizado no Mundo Laboral; d) O Enfermeiro e Sua Participação na Reabilitação do Cliente Estomizado. Os resultados revelaram que a maioria dos sujeitos trabalhava informalmente e recebia ao mesmo tempo algum auxílio governamental. Ressalta-se que eles reconheciam a ilegalidade desta situação, porém, julgavam-na necessária devido aos baixos valores dos benefícios, enfatizando-se a sensação de utilidade causada pelo fato de trabalharem. Referiram que o retorno ao trabalho era prejudicado devido a empecilhos encontrados nas dimensões psíquica, física e social, as quais estavam articuladas intimamente. Enfatizaram grande dificuldade em encontrarem empregos adequados às suas especificidades, e que não prejudicassem sua condição de saúde, pois há necessidade de banheiros adaptados, de não exposição ao calor na região do estoma e nem a esforços físicos severos, sem contar com a necessidade de um emprego que lhes permita flexibilidade para irem às consultas da equipe multiprofissional. Os maiores empecilhos sociais referiram-se ao desconhecimento e descaso social e governamental a respeito do que é ser estomizado, pois esta problemática não é divulgada, e nem conhecida pela maioria da população. Em relação aos enfermeiros, os sujeitos foram quase unânimes em referirem falta de orientação por parte desses profissionais, acerca de esclarecerem sobre sua inclusão no mundo do trabalho. Este fato caracterizou-se como preocupante, pois os enfermeiros são educadores por excelência e a orientação está intimamente ligada ao processo de reabilitação. Concluiu-se que o retorno ao trabalho foi considerado essencial, mas existem inúmeras dificuldades para que este retorno e manutenção no universo laboral. Estes empecilhos os levam a adquirirem aposentadorias precoces ou auxílios-doença. Há de se rever o processo de reabilitação da pessoa com estoma, especialmente no que se refere a sua inclusão no mundo do trabalho, no sentido de melhor prepará-la para suas potencialidades e limitações, destacando-se que ela não é incapaz e que existem atividades formais em que elas podem ser produtivas e felizes.

Magnetic moments in amorpous palladium-cobalt-silicon alloys

The magnetic moments of amorphous ternary alloys containing Pd, Co and Si in atomic concentrations corresponding to Pd_(80-x)Co_xSi_(20) in which x is 3, 5, 7, 9, 10 and 11, have been measured between 1.8 and 300°K and in magnetic fields up to 8.35 kOe. The alloys were obtained by rapid quenching of a liquid droplet and their structures were analyzed by X-ray diffraction. The measurements were made in a null-coil pendulum magnetometer in which the temperature could be varied continuously without immersing the sample in a cryogenic liquid. The alloys containing 9 at.% Co or less obeyed Curie's Law over certain temperature ranges, and had negligible permanent moments at room temperature. Those containing 10 and 11 at.% Co followed Curie's Law only above approximately 200°K and had significant permanent moments at room temperature. For all alloys, the moments calculated from Curie's Law were too high to be accounted for by the moments of individual Co atoms. To explain these findings, a model based on the existence of superparamagnetic clustering is proposed. The cluster sizes calculated from the model are consistent with the rapid onset of ferromagnetism in the alloys containing 10 and 11 at.% Co and with the magnetic moments in an alloy containing 7 at.% Co heat treated in such a manner as to contain a small amount of a crystalline phase. In alloys containing 7 at.% Co or less, a maximum in the magnetization vs temperature curve was observed around 10°K. This maximum was eliminated by cooling the alloy in a magnetic field, and an explanation for this observation is suggested.