Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 22
Filtrar
Mais filtros








Base de dados
Intervalo de ano de publicação
1.
Phys Rev Lett ; 120(20): 204801, 2018 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-29864368

RESUMO

A dual ion species plasma expansion scheme from a novel target structure is introduced, in which a nanometer-thick layer of pure deuterium exists as a buffer species at the target-vacuum interface of a hydrogen plasma. Modeling shows that by controlling the deuterium layer thickness, a composite H^{+}/D^{+} ion beam can be produced by target normal sheath acceleration (TNSA), with an adjustable ratio of ion densities, as high energy proton acceleration is suppressed by the acceleration of a spectrally peaked deuteron beam. Particle in cell modeling shows that a (4.3±0.7) MeV per nucleon deuteron beam is accelerated, in a directional cone of half angle 9°. Experimentally, this was investigated using state of the art cryogenic targetry and a spectrally peaked deuteron beam of (3.4±0.7) MeV per nucleon was measured in a cone of half angle 7°-9°, while maintaining a significant TNSA proton component.

2.
Science ; 345(6197): 644-6, 2014 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-25104380

RESUMO

Origami can turn a sheet of paper into complex three-dimensional shapes, and similar folding techniques can produce structures and mechanisms. To demonstrate the application of these techniques to the fabrication of machines, we developed a crawling robot that folds itself. The robot starts as a flat sheet with embedded electronics, and transforms autonomously into a functional machine. To accomplish this, we developed shape-memory composites that fold themselves along embedded hinges. We used these composites to recreate fundamental folded patterns, derived from computational origami, that can be extrapolated to a wide range of geometries and mechanisms. This origami-inspired robot can fold itself in 4 minutes and walk away without human intervention, demonstrating the potential both for complex self-folding machines and autonomous, self-controlled assembly.

3.
J Econ Entomol ; 107(3): 1201-5, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25026683

RESUMO

A durable termite bait containing 0.5% noviflumuron was evaluated for physical durability, retention of active ingredient, consumption by termites, and toxicity to termites over 5 yr in field studies at locations in Indiana, Mississippi, and South Carolina. Plots in Indiana and Mississippi included both natural rainfall and irrigated plots, while plots in South Carolina received only natural rainfall. Samples collected every 3 mo for the first 4 yr were evaluated for consumption with a 7 d no-choice bioassay using Reticulitermes flavipes (Kollar). Consumption and toxicity of 5 yr samples were evaluated in similar bioassays conducted for 42 d. Durable baits received from field sites had some cracking, and a small amount of external flaking, but no major deterioration based on visual observation. There were no significant differences in noviflumuron concentration over the 5-yr period and no trend toward reduced concentrations of noviflumuron over time. Consumption of aged durable baits over 4 yr was variable, but termites usually consumed more aged durable bait than fresh durable bait and the differences were frequently significant. There were some exceptions, but termites consumed significantly more fresh durable bait than aged durable bait in only 4% of observations. When 5 yr samples were evaluated, consumption was lowest for fresh durable bait and termites consumed significantly more aged durable bait from irrigated plots in Indiana and from both natural and irrigated plots in Mississippi than fresh durable bait. Survival of termites fed blank durable bait was significantly higher than that for termites fed any of the baits containing noviflumuron and there were no significant differences in survival among the noviflumuron durable baits. Our results suggest that the bait would be durable for at least 5 yr and possibly longer under most environmental conditions.


Assuntos
Benzamidas , Hidrocarbonetos Fluorados , Controle de Insetos/métodos , Inseticidas , Isópteros , Animais , Celulose , Indiana , Controle de Insetos/instrumentação , Mississippi , Estações do Ano , Solo , South Carolina , Fatores de Tempo
4.
Phys Med ; 30(3): 255-70, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24100298

RESUMO

Suitable instrumentation for laser-accelerated proton (ion) beams is critical for development of integrated, laser-driven ion accelerator systems. Instrumentation aimed at beam diagnostics and control must be applied to the driving laser pulse, the laser-plasma that forms at the target and the emergent proton (ion) bunch in a correlated way to develop these novel accelerators. This report is a brief overview of established diagnostic techniques and new developments based on material presented at the first workshop on 'Instrumentation for Diagnostics and Control of Laser-accelerated Proton (Ion) Beams' in Abingdon, UK. It includes radiochromic film (RCF), image plates (IP), micro-channel plates (MCP), Thomson spectrometers, prompt inline scintillators, time and space-resolved interferometry (TASRI) and nuclear activation schemes. Repetition-rated instrumentation requirements for target metrology are also addressed.


Assuntos
Lasers , Aceleradores de Partículas/instrumentação , Prótons , Análise Espectral
5.
J Econ Entomol ; 105(2): 533-9, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22606824

RESUMO

Using a quarterly (3-mo) monitoring and bait-replenishment interval, 122 subterranean termite colonies throughout the United States were baited with a refined cellulose bait matrix containing 0.5% noviflumuron. All colonies were eliminated in less than 1 yr after initiation of baiting as determined by long-term monitoring and genetic markers. Sixty-three percent of the colonies were eliminated during the first quarter after the initiation of baiting and 77% of colonies were eliminated after consuming two bait tubes or less. This suggests that a single baiting cycle and bait installed in response to a single active monitoring device were sufficient to eliminate the majority of colonies. Although termites temporarily abandoned stations after depleting bait, workers resumed feeding when baits were replenished. Colonies that consumed large amounts of bait before elimination foraged into multiple stations, thus allowing adequate amounts of bait to sustain feeding. The time to eliminate termite colonies with bait replenished quarterly was similar to that previously reported for laminated cellulose bait replenished monthly. Our data support the conclusion that extending the bait replenishment interval from monthly to quarterly for bait tubes with refined cellulose containing 0.5% noviflumuron did not adversely impact colony elimination.


Assuntos
Benzamidas , Hidrocarbonetos Fluorados , Controle de Insetos/métodos , Inseticidas , Isópteros , Animais , Celulose , Controle de Insetos/instrumentação , Estações do Ano , Especificidade da Espécie , Fatores de Tempo , Estados Unidos
6.
Cells Tissues Organs ; 171(4): 269-75, 2002.
Artigo em Inglês | MEDLINE | ID: mdl-12169824

RESUMO

This theoretical analysis tries to explain the decrease of the femoral neck anteversion during growth according to well-established concepts. In the frontal plane, it was demonstrated that the capital epiphyseal plate inclination allows the plate to remain perpendicular to the resultant force applied to the hip during gait. In the transversal plane, the projection of this force varies from -24 degrees, outwards and forwards (heel strike), to 20 degrees, outwards and backwards (toe off). A mathematical formula calculates the instantaneous coordinates of the plate in this plane during gait. This kinematic study points out that the physiological value of the capital epiphyseal plate anteversion at the end of the growth is theoretically the ideal value to obtain in the transversal or horizontal plane a perpendicular relation between the orientation of this plate and the projection of the resultant force during walking.


Assuntos
Colo do Fêmur/crescimento & desenvolvimento , Colo do Fêmur/fisiologia , Fenômenos Biomecânicos , Colo do Fêmur/anatomia & histologia , Lâmina de Crescimento/anatomia & histologia , Lâmina de Crescimento/crescimento & desenvolvimento , Lâmina de Crescimento/fisiologia , Humanos , Modelos Biológicos
7.
Environ Technol ; 23(7): 731-45, 2002 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-12164635

RESUMO

Resistance to Cr(VI) is usually associated with its cellular exclusion, precluding enrichment techniques for the isolation of organisms accumulating Cr(VI) via bioreduction to insoluble Cr(III). A technique was developed to screen for potential Cr(VI) reduction in approx. 2000 isolates from a coastal environment, based on the non-specific reduction of selenite and tellurite to Se0 and Te0, and reduction of tetrazolium blue to insoluble blue formazan. The most promising strains were further screened in liquid culture, giving three, which were identified by 16S rRNA sequence analysis as Bacillus pumilus, Exiguobacterium aurantiacum and Pseudomonas synxantha, all of which reduced 100 microM Cr(VI) anaerobically, without growth. The respective removal of Cr(VI) was 90% and 80% by B. pumilus and E. aurantiacum after 48 h and 80% and by P. synxantha after 192 h. With the gram positive strains Cr(VI) promoted loss of flagella and, in the case of B. pumilus, lysis of some cells, but Cr was deposited as an exocellular precipitate which was identified as containing Cr and P using energy dispersive X-ray microanalysis (EDAX). This prompted the testing of Citrobacter sp. N14 (subsequently re-assigned by 16S rRNA sequence analysis and biochemical studies as a strain of Serratia) which bioprecipitates metal cation phosphates via enzymatically-liberated phosphate. This strain reduced Cr(VI) at a rate comparable to that of P. synxantha but Cr(III) was not bioprecipitated where La(III) was removed as LaPO4, even though a similar amount of phosphate was produced in the presence of Cr(III). Since B. pumilus removed most of the Cr(VI), with the formation of cell-bound CrPO4 implicated, this suggests that this strain could have future bioprocess potential.


Assuntos
Bacillus/fisiologia , Carcinógenos Ambientais/metabolismo , Cromo/metabolismo , Pseudomonas/fisiologia , Biodegradação Ambiental , Precipitação Química , Oxirredução
8.
Eur J Morphol ; 40(1): 23-7, 2002 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-12959345

RESUMO

An accurate knowledge of the relationship between the neck and the epiphyseal plate at the end of growth is important for biomechanical investigations of femoral neck remodelling during childhood. Statistical data about the position of the epiphyseal femoral cartilage in relation to the neck axis at the end of the growth, are rare in the literature. As the trace of the epiphysis can be observed on a CT scan view of an adult hip, cadaver femurs were investigated to study this relationship and to avoid irradiation of children. The mean anteversion angle of the epiphyseal line towards the patient's coronal plane is 2.3 degrees. The plate is retroverted in an average of 8.2 degrees in relation to the neck axis and is related to neck anteversion. The more the neck is anteverted, the more the plate is retroverted.


Assuntos
Fêmur/anatomia & histologia , Fêmur/diagnóstico por imagem , Lâmina de Crescimento/anatomia & histologia , Lâmina de Crescimento/diagnóstico por imagem , Tomografia Computadorizada por Raios X/normas , Humanos , Valores de Referência
9.
J Shoulder Elbow Surg ; 10(6): 546-9, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11743533

RESUMO

Computed tomography (CT) allows calculation of anatomic and prosthetic humeral head retroversion. The purpose of this study was to demonstrate how the retroversion angle measured by CT scan varied with changes in arm position in the CT scan reference system. A trigonometric analysis shows that the measured retroversion angle decreases when the arm is in extension and increases when it is in flexion, compared with the true retroversion angle determined perioperatively. For the same degree of flexion, or extension, the error of measurement is greater when the initial true retroversion is low. A shoulder prosthesis with 20 degrees of true head retroversion was radiologically scanned with different degrees of flexion, extension, and abduction. The results validate the theoretical analysis. Trigonometric formulas are proposed to correct the retroversion angle measured by CT scan.


Assuntos
Fenômenos Biomecânicos , Prótese Articular , Amplitude de Movimento Articular , Articulação do Ombro/diagnóstico por imagem , Tomografia Computadorizada por Raios X/métodos , Humanos , Desenho de Prótese , Ajuste de Prótese , Sensibilidade e Especificidade
10.
J Radiol ; 80(12): 1636-41, 1999 Dec.
Artigo em Francês | MEDLINE | ID: mdl-10642657

RESUMO

PURPOSE: The false profile X-Ray view as described by Lequesne, allowing the measurement of the anterior cover of the acetabulum, is a slantwise view obtained by a 65 degrees inclination of the pelvis on the radiographic plate. The errors introduced by this radiological measurement of the anterior cover are evaluated. MATERIALS AND METHODS: An anatomical and radiological analysis is conducted on 20 acetabula. The anterior cover is measured on the bone and the A point, the anterior extremity of the acetabular roof, is plumbed. Each pelvis is imaged following the Lequesne method. The VCA angle is measured with the radiological point A described by Lequesne and with the metallic point A as reference. RESULTS: The difference between the anatomical and radiological values of the anterior cover is an average by 11 degrees and undervalues the anatomical value. The deviation is reduced by the application of a trigonometrical formula. A difference between the radiological localisation of A point described by Lequesne and the metallic marker is pointed out. This difference increases when the acetabulum becomes dysplasic. CONCLUSION: The acetabular anterior cover measured with the radiological incidence described by Lequesne undervalues the real value. Moreover, the error increases when the acetabulum is dysplasic.


Assuntos
Acetábulo/anatomia & histologia , Acetábulo/diagnóstico por imagem , Antropometria , Viés , Humanos , Matemática , Radiografia , Reprodutibilidade dos Testes
11.
Acta Orthop Belg ; 65(4): 485-91, 1999 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-10675944

RESUMO

The authors propose a simple and practical method to measure radiologically the angle of ante- or retroversion of the acetabular cup using a goniometer. It only necessitates an anteroposterior radiograph centered on the femoral head and another one centered on the public symphysis. Special x ray equipment, compass, conversion table, mathematical formulas, or a pocket calculator are not required. The opening of the prosthetic cup is projected on the film as an ellipse. According to the rules of descriptive geometry, the true size of the angle of anteversion is easily obtained. The geometric constructions consist in drawing four lines. The adequate positioning on a hip radiograph of the protractor, drawn on the goniometer, permits the direct reading of the true and planar anteversion angles of the cup.


Assuntos
Acetábulo/diagnóstico por imagem , Artroplastia de Quadril , Prótese de Quadril , Cabeça do Fêmur/diagnóstico por imagem , Humanos , Matemática , Variações Dependentes do Observador , Desenho de Prótese , Sínfise Pubiana/diagnóstico por imagem , Radiografia , Propriedades de Superfície
12.
J Radiol ; 79(8): 743-50, 1998 Aug.
Artigo em Francês | MEDLINE | ID: mdl-9757304

RESUMO

A coxometric evaluation is helpful for the diagnosis and the prognosis of hip dysplasia. These measurements also given an intrinsic guide to the surgeon for total hip arthroplasty. A coxometric protractor is drawn on the majority of the goniometers and allows the measurement of the angle of internal and external roof, the angle of the acetabular roof obliquity and the femoral neck-shaft angle on a hip AP X-ray. The purpose of this report is to demonstrate that on the same X-ray, the adequate placement of the coxometric protractor allows to calculate the inclination angle, the acetabular anteversion angles and the anterior roof angle.


Assuntos
Acetábulo/diagnóstico por imagem , Luxação do Quadril/diagnóstico por imagem , Articulação do Quadril/diagnóstico por imagem , Acetábulo/anatomia & histologia , Colo do Fêmur/anatomia & histologia , Colo do Fêmur/diagnóstico por imagem , Articulação do Quadril/anatomia & histologia , Humanos , Tomografia Computadorizada por Raios X
13.
J Gerontol Nurs ; 23(10): 7-12, 1997 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-9384090

RESUMO

1. The move to a long-term care facility often strips elders of self-control and decision-making, leading to a sense of powerlessness and low self-esteem. 2. Life is measured day to day. Restoring choices in activities of daily living, nutrition and fluids, and social activities allows clients to function at maximum autonomy while reducing the workload of staff. 3. The key is a change of focus. Innovative changes providing variety and choice in long-term care facilities are achievable and cost-effective.


Assuntos
Idoso/psicologia , Enfermagem Geriátrica/métodos , Assistência de Longa Duração/psicologia , Participação do Paciente , Poder Psicológico , Atividades Cotidianas , Humanos , Controle Interno-Externo , Relações Enfermeiro-Paciente
14.
FEMS Microbiol Rev ; 14(4): 351-67, 1994 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-7917422

RESUMO

A biological process for the removal of heavy metals from the aqueous flows is described. Metals are precipitated on the surface of immobilized cells of a Citrobacter sp. as cell-bound metal phosphates. This uses phosphate liberated by the activity of a cell-bound phosphatase. Some radionuclides (e.g. 241americium) form metal phosphates readily; efficient removal of 241Am on a continuous basis is demonstrated. At low phosphatase activities, the efficiency of uranium removal correlates with enzyme activity. High phosphatase activities are not realised as an increase in metal removal, suggesting that chemical events become rate-limiting. Studies have suggested that maximal metal uptake occurs only after nucleation and the formation of precipitation foci. A model is presented to illustrate how nucleation and crystallization processes could enhance the removal of plutonium and neptunium from dilute solutions.


Assuntos
Amerício/isolamento & purificação , Citrobacter/enzimologia , Monoéster Fosfórico Hidrolases/metabolismo , Plutônio/isolamento & purificação , Poluentes Radioativos da Água/isolamento & purificação , Resinas Acrílicas , Európio/isolamento & purificação , Lantânio/isolamento & purificação , Resíduos Radioativos
17.
J Mol Biol ; 216(4): 883-95, 1990 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-2266560

RESUMO

The TonB protein is required for several outer membrane transport processes in bacteria. A short 33-residue peptide segment of TonB has been studied by 1H and 13C nuclear magnetic resonance spectroscopy. The sequence of this peptide segment contains multiple Glu-Pro and Lys-Pro dipeptide repeats that maintain rigid, elongated structures and flank a short connecting segment that adopts a beta-strand configuration. This TonB peptide is shown to interact specifically with the FhuA protein, the outer membrane receptor for ferrichrome-iron, providing the first direct evidence that the TonB protein interacts with outer membrane receptors. Interaction with the FhuA protein involves the extended structural element containing positively charged Lys-Pro repeats, and suggests a functional role for this segment of the TonB protein. As TonB is anchored in the cytoplasmic membrane the protein must, uniquely, span the periplasm. These data, together with studies described in the accompanying paper, suggest a model by which TonB serves to transduce conformational information over extended distances, from the cytoplasmic membrane to the outer membrane.


Assuntos
Proteínas de Bactérias/metabolismo , Proteínas de Escherichia coli , Escherichia coli/fisiologia , Proteínas de Membrana/metabolismo , Receptores Virais , Salmonella typhimurium/fisiologia , Sequência de Aminoácidos , Proteínas da Membrana Bacteriana Externa/metabolismo , Proteínas de Bactérias/química , Transporte Biológico , Espectroscopia de Ressonância Magnética , Proteínas de Membrana/química , Dados de Sequência Molecular , Estrutura Molecular , Fragmentos de Peptídeos/metabolismo , Ligação Proteica , Conformação Proteica , Relação Estrutura-Atividade
18.
Int Nurs Rev ; 34(1): 12-4, 1987.
Artigo em Inglês | MEDLINE | ID: mdl-3643892

RESUMO

In an effort to provide accessible and affordable health care to the populations of the world, governments and non-governmental organizations have turned to primary health care. The Maua Methodist Hospital in the community health Maua Via Meru, Kenya, gives us an example of such efforts.


Assuntos
Tomada de Decisões , Modelos Teóricos , Atenção Primária à Saúde/organização & administração , Serviços de Saúde Comunitária/organização & administração , Humanos , Quênia , Projetos Piloto
19.
Br Med J (Clin Res Ed) ; 283(6284): 115-8, 1981 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-6789932

RESUMO

A total of 108 orthotopic liver transplants have been carried out in the Cambridge/King's College Hospital series. Over 13 years, changes in patient selection, immunosuppression, and surgical and anaesthetic techniques have led to a steady improvement in results. Results obtained in the last 22 patients indicated that over half survive for one year. Although at considerable risk during the operation, patients with non-malignant cirrhotic diseases who survive one year have a good long-term chance of survival


Assuntos
Hepatopatias/cirurgia , Transplante de Fígado , Adolescente , Adulto , Fatores Etários , Facilitação Imunológica de Enxerto/métodos , Rejeição de Enxerto , Humanos , Hepatopatias/mortalidade , Pessoa de Meia-Idade , Cuidados Pós-Operatórios/métodos , Complicações Pós-Operatórias/mortalidade , Prognóstico , Transplante Homólogo/métodos
20.
Ann R Coll Surg Engl ; 59(6): 502-6, 1977 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-931330

RESUMO

The management of patients with severe hepatic trauma and damage to the inferior vena cava presents many difficulties. Our experience suggests that vena caval injury is more common than has previously been reported. In spite of the severity of the injuries a period for resuscitation is usually available and operation must not be started until full supportive measures are ready. We have evolved a technique of vascular isolation of the liver aboiding the use of internal vena caval shunts that permits repair of the damaged vena cava.


Assuntos
Fígado/lesões , Veia Cava Inferior/lesões , Humanos , Fígado/irrigação sanguínea , Fígado/cirurgia , Métodos , Veia Cava Inferior/cirurgia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA