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1.
Nature ; 605(7911): 653-658, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35364602

RESUMO

Before the Perseverance rover landing, the acoustic environment of Mars was unknown. Models predicted that: (1) atmospheric turbulence changes at centimetre scales or smaller at the point where molecular viscosity converts kinetic energy into heat1, (2) the speed of sound varies at the surface with frequency2,3 and (3) high-frequency waves are strongly attenuated with distance in CO2 (refs. 2-4). However, theoretical models were uncertain because of a lack of experimental data at low pressure and the difficulty to characterize turbulence or attenuation in a closed environment. Here, using Perseverance microphone recordings, we present the first characterization of the acoustic environment on Mars and pressure fluctuations in the audible range and beyond, from 20 Hz to 50 kHz. We find that atmospheric sounds extend measurements of pressure variations down to 1,000 times smaller scales than ever observed before, showing a dissipative regime extending over five orders of magnitude in energy. Using point sources of sound (Ingenuity rotorcraft, laser-induced sparks), we highlight two distinct values for the speed of sound that are about 10 m s-1 apart below and above 240 Hz, a unique characteristic of low-pressure CO2-dominated atmosphere. We also provide the acoustic attenuation with distance above 2 kHz, allowing us to explain the large contribution of the CO2 vibrational relaxation in the audible range. These results establish a ground truth for the modelling of acoustic processes, which is critical for studies in atmospheres such as those of Mars and Venus.

3.
Geophys Res Lett ; 46(19): 10754-10763, 2019 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-31894167

RESUMO

The Mars Science Laboratory Curiosity rover is traversing a sequence of stratified sedimentary rocks in Gale crater that contain varied eolian, fluviodeltaic, and lake deposits, with phyllosilicates, iron oxides, and sulfate salts. Here, we report the chloride salt distribution along the rover traverse. Chlorine is detected at low levels (<3 wt.%) in soil and rock targets with multiple MSL instruments. Isolated fine-scale observations of high chlorine (up to ≥15 wt.% Cl), detected using the ChemCam instrument, are associated with elevated Na2O and interpreted as halite grains or cements in bedrock. Halite is also interpreted at the margins of veins and in nodular, altered textures. We have not detected halite in obvious evaporitic layers. Instead, its scattered distribution indicates that chlorides emplaced earlier in particular members of the Murray formation were remobilized and reprecipitated by later groundwaters within Murray formation mudstones and in diagenetic veins and nodules.

4.
Eur J Nutr ; 54 Suppl 2: 27-34, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26066355

RESUMO

PURPOSE: To compare (1) fluid, food and nutrient intake obtained with a paper versus an online version of a 7-day food record and (2) user's acceptability of both versions of the food record. METHODS: A cross-over study was carried out in 2010 in France. A total of 246 participants aged 18-60 years reported their food and fluid intake using both versions of the 7-day food record, separated by a 7- to 14-day washout period. To help participants in estimating consumed portions, both versions of the food record were supported by a photographic booklet of standard portions and containers. At the end of the study protocol, participants completed a questionnaire designed to assess the acceptability of the two questionnaires. RESULTS: The reported water intake of fluids was significantly higher with the online version compared with the paper version (respectively 1348 ± 36 and 1219 ± 34 mL/day, p < 0.0001). No difference was found between methods in terms of energy intake and the consumption of most food categories, macro- and micronutrients. Furthermore, 77 % of the participants preferred the online method to the paper version. CONCLUSIONS: Fluid intake, but not food intake, reported with the online 7-day food record was higher in comparison with the paper version. In addition, the online version was preferred by users. In population surveys, the online record is therefore a relevant alternative, and even a preferred alternative in the case of fluid intake, to the paper record.


Assuntos
Bebidas , Dieta , Ingestão de Líquidos , Avaliação Nutricional , Política Nutricional , Aceitação pelo Paciente de Cuidados de Saúde , Cooperação do Paciente , Adulto , Atitude Frente a Saúde , Bebidas/análise , Estudos de Coortes , Estudos Cross-Over , Desidratação/etnologia , Desidratação/prevenção & controle , Dieta/efeitos adversos , Dieta/etnologia , Registros de Dieta , Ingestão de Líquidos/etnologia , Feminino , Análise de Alimentos , França , Humanos , Internet , Masculino , Aceitação pelo Paciente de Cuidados de Saúde/etnologia , Cooperação do Paciente/etnologia , Recomendações Nutricionais , Autorrelato , Água/administração & dosagem , Água/análise
5.
Odontostomatol Trop ; 38(149): 5-9, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26058304

RESUMO

Anesthetizing MIH (Molar and Incisor Hypomineralisation) teeth is one of the major challenges in paediatric dentistry. Computer-assisted IO injection (CAIO) of 4% articaine with 1:200,000 epinephrine (Alphacaine, Septodont) has been shown to be an efficient way to anesthetize teeth in children. The aim of this study was to assess the efficacy of this method with MIH teeth. This preliminary study was performed using the Quick Sleeper system (Dental Hi Tec, Cholet, France) that allows computer-controlled rotation of the needle to penetrate the bone and computer-controlled injection of the anaesthetic solution. Patients (39) of the department of Paediatric Dentistry were included allowing 46 sessions (including 32 mandibular first permanent molars) to be assessed. CAIO showed efficacy in 93.5% (43/46) of cases. Failures (3) were due to impossibility to reach the spongy bone (1) and to achieve anaesthesia (2). This prospective study confirms that CAIO anaesthesia is a promising method to anesthetize teeth with MIH that could therefore be routinely used by trained practitioners.


Assuntos
Anestesia Dentária/métodos , Anestesia Local/métodos , Anestésicos Locais/administração & dosagem , Hipoplasia do Esmalte Dentário/terapia , Terapia Assistida por Computador/métodos , Carticaína/administração & dosagem , Criança , Epinefrina/administração & dosagem , Feminino , Humanos , Injeções/instrumentação , Injeções/métodos , Masculino , Mandíbula/efeitos dos fármacos , Estudos Prospectivos , Estudos Retrospectivos , Rotação , Resultado do Tratamento , Vasoconstritores/administração & dosagem
6.
Sci Rep ; 14(1): 11284, 2024 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-38760365

RESUMO

Planetary exploration relies considerably on mineral characterization to advance our understanding of the solar system, the planets and their evolution. Thus, we must understand past and present processes that can alter materials exposed on the surface, affecting space mission data. Here, we analyze the first dataset monitoring the evolution of a known mineral target in situ on the Martian surface, brought there as a SuperCam calibration target onboard the Perseverance rover. We used Raman spectroscopy to monitor the crystalline state of a synthetic apatite sample over the first 950 Martian days (sols) of the Mars2020 mission. We note significant variations in the Raman spectra acquired on this target, specifically a decrease in the relative contribution of the Raman signal to the total signal. These observations are consistent with the results of a UV-irradiation test performed in the laboratory under conditions mimicking ambient Martian conditions. We conclude that the observed evolution reflects an alteration of the material, specifically the creation of electronic defects, due to its exposure to the Martian environment and, in particular, UV irradiation. This ongoing process of alteration of the Martian surface needs to be taken into account for mineralogical space mission data analysis.

7.
Int J Oral Maxillofac Surg ; 51(8): 1059-1068, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35012826

RESUMO

The aim of this study was to evaluate the revision rate after total alloplastic temporomandibular joint replacement (TMJR) and determine whether there is a higher risk of revision surgery with stock or custom-fitted prostheses (the two most current TMJR prosthesis types). A systematic review was performed, with a search of PubMed, Google Scholar, and the Cochrane Library in November 2020. Overall, 27 articles were included in this study, describing Biomet and TMJ Concepts prostheses and including postoperative data on complications requiring a return to the operating room. A total of 2247 prostheses were analysed: 1350 stock Biomet prostheses and 897 custom-fitted TMJ Concepts and custom-fitted Biomet prostheses. The global revision rate was 1.19 per 100 prosthesis-years. The most common reason for revision was heterotopic bone formation. Stock prostheses appeared to have a lower risk of revision compared to custom prostheses: rate ratio 0.52 (95% confidence interval 0.33-0.81, P-value 0.003). Regarding causes of revision, the only significant difference between the types of devices was a higher rate of heterotopic bone formation for custom-made prostheses (P = 0.001). The results of this study revealed a low revision rate post TMJR revision, with stock devices even less prone to such risk. Nevertheless, these results can be explained by the fact that custom-made prostheses are more likely to be used for cases in which the anatomy is significantly abnormal or there is a history of multiple joint surgeries, which carry a greater risk of complications and heterotopic bone formation.


Assuntos
Artroplastia de Substituição , Prótese Articular , Ossificação Heterotópica , Transtornos da Articulação Temporomandibular , Artroplastia de Substituição/métodos , Cimetidina , Humanos , Ossificação Heterotópica/cirurgia , Articulação Temporomandibular/cirurgia , Transtornos da Articulação Temporomandibular/cirurgia
8.
Anal Chim Acta ; 1209: 339837, 2022 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-35569848

RESUMO

The SuperCam instrument, onboard the Perseverance rover (Mars 2020 mission) is designed to perform remote analysis on the Martian surface employing several spectroscopic techniques such as Laser Induced Breakdown Spectroscopy (LIBS), Time-Resolved Raman (TRR), Time-Resolved Fluorescence (TRF) and Visible and Infrared (VISIR) reflectance. In addition, SuperCam also acquires high-resolution images using a color remote micro-imager (RMI) as well as sounds with its microphone. SuperCam has three main subsystems, the Mast Unit (MU) where the laser for chemical analysis and collection optics are housed, the Body Unit (BU) where the different spectrometers are located inside the rover, and the SuperCam Calibration Target (SCCT) located on the rover's deck to facilitate calibration tests at similar ambient conditions as the analyzed samples. To perform adequate calibrations on Mars, the 22 mineral samples included in the complex SCCT assembly must have a very homogeneous distribution of major and minor elements. The analysis and verification of such homogeneity for the 5-6 replicates of the samples included in the SCCT has been the aim of this work. To verify the physic-chemical homogeneity of the calibration targets, micro Energy Dispersive X-ray Fluorescence (EDXRF) imaging was first used on the whole surface of the targets, then the relative abundances of the detected elements were computed on 20 randomly distributed areas of 100 × 100 µm. For those targets showing a positive Raman response, micro-Raman spectroscopy imaging was performed on the whole surface of the targets at a resolution of 100 × 100 µm. The %RSD values (percent of relative standard deviation of mean values) for the major elements measured with EDXRF were compared with similar values obtained by two independent LIBS set-ups at spot sizes of 300 µm in diameter. The statistical analysis showed which elements were homogeneously distributed in the 22 mineral targets of the SCCT, providing their uncertainty values for further calibration. Moreover, nine of the 22 targets showed a good Raman response and their mineral distributions were also studied. Those targets can be also used for calibration purposes of the Raman part of SuperCam using the wavenumbers of their main Raman bands proposed in this work.


Assuntos
Meio Ambiente Extraterreno , Marte , Calibragem , Meio Ambiente Extraterreno/química , Minerais/análise , Análise Espectral Raman/métodos
9.
Science ; 377(6614): eabo2196, 2022 09 30.
Artigo em Inglês | MEDLINE | ID: mdl-36007009

RESUMO

The Perseverance rover landed in Jezero crater, Mars, to investigate ancient lake and river deposits. We report observations of the crater floor, below the crater's sedimentary delta, finding that the floor consists of igneous rocks altered by water. The lowest exposed unit, informally named Séítah, is a coarsely crystalline olivine-rich rock, which accumulated at the base of a magma body. Magnesium-iron carbonates along grain boundaries indicate reactions with carbon dioxide-rich water under water-poor conditions. Overlying Séítah is a unit informally named Máaz, which we interpret as lava flows or the chemical complement to Séítah in a layered igneous body. Voids in these rocks contain sulfates and perchlorates, likely introduced by later near-surface brine evaporation. Core samples of these rocks have been stored aboard Perseverance for potential return to Earth.

10.
Eur Arch Paediatr Dent ; 22(5): 801-811, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33840073

RESUMO

PURPOSE: Management of a child's anxiety early in their treatment is essential in dentistry. Sedative medications are used to overcome increased anxiety from previous appointments and to promote the cooperation of children during treatment. Hydroxyzine is currently prescribed to young patients as part of the first level of conscious sedation. The main objective was to evaluate the professional practice of oral hydroxyzine, when prescribed for children presenting anxiety during dental treatment procedure performed by students and senior practitioners. METHODS: A retrospective study of dental records and questionnaires was conducted at the Dental Care Centre of the University Hospital of Rennes, France. Parameters related to the prescription of hydroxyzine in children were evaluated as potential predictors of the dental session success, with adjustments on potential confounders. RESULTS: The therapeutic outcome was very encouraging with 78.3% of success during dental sessions under sedation with oral hydroxyzine. Anxiety levels before the dental procedure and the medication compliance of the child were the main predictors of success. On the other hand, lower age (< 6 years old) and longer treatments (such as pulpotomy) worsened the outcome. CONCLUSIONS: Careful analysis of the literature and results of this work showed the safety of hydroxyzine within the maximum dose authorized without adverse effects, compared to other molecules described and commonly used in dentistry. No adverse effects during dental procedure were noted. This allows for minimal sedation with efficiency for the great majority of pediatric treatment. This solution should be the first step in sedation to help practicing clinicians.


Assuntos
Anestesia Dentária , Hidroxizina , Criança , Comportamento Infantil , Sedação Consciente , Hospitais , Humanos , Hipnóticos e Sedativos/efeitos adversos , Prática Profissional , Estudos Retrospectivos
11.
Space Sci Rev ; 216(8): 138, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33281235

RESUMO

SuperCam is a highly integrated remote-sensing instrumental suite for NASA's Mars 2020 mission. It consists of a co-aligned combination of Laser-Induced Breakdown Spectroscopy (LIBS), Time-Resolved Raman and Luminescence (TRR/L), Visible and Infrared Spectroscopy (VISIR), together with sound recording (MIC) and high-magnification imaging techniques (RMI). They provide information on the mineralogy, geochemistry and mineral context around the Perseverance Rover. The calibration of this complex suite is a major challenge. Not only does each technique require its own standards or references, their combination also introduces new requirements to obtain optimal scientific output. Elemental composition, molecular vibrational features, fluorescence, morphology and texture provide a full picture of the sample with spectral information that needs to be co-aligned, correlated, and individually calibrated. The resulting hardware includes different kinds of targets, each one covering different needs of the instrument. Standards for imaging calibration, geological samples for mineral identification and chemometric calculations or spectral references to calibrate and evaluate the health of the instrument, are all included in the SuperCam Calibration Target (SCCT). The system also includes a specifically designed assembly in which the samples are mounted. This hardware allows the targets to survive the harsh environmental conditions of the launch, cruise, landing and operation on Mars during the whole mission. Here we summarize the design, development, integration, verification and functional testing of the SCCT. This work includes some key results obtained to verify the scientific outcome of the SuperCam system.

12.
Cytometry A ; 75(12): 1015-9, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19845019

RESUMO

We present an efficient high-throughput flow cytometric method that builds on previously published methods and permits rapid ploidy discrimination in plants. By using Brassica napus L. microspore-derived plants as an example, we describe how 192 leaf tissue samples may be processed and analyzed comfortably by one operator in 6 h from tissue sampling to ploidy determination. The technique involves placing young leaf samples in two 96-well racks, using a bead-beating procedure to release nuclei into a lysis solution, filtering the samples on 96-well filter plates, staining with propidium iodide, and then rapidly estimating DNA ploidy using a plate loader on a BD FACS-Canto II flow cytometer. Throughout the sample preparation process, multichannel pipetting allows faster and less error-prone sample handling. In two 96-well plates of samples, the histogram peaks of DNA content from flow cytometry were wellresolved in 189 of 192 samples tested (98.4%), with CV values ranging from 2.98% to 6.20% with an average CV of 4.35% (SD = 0.68%). This new method is useful in doubled haploid plant breeding programs where early discrimination of haploid and doubled haploid (i.e., diploid) plantlets can confer significantly improved operational efficiencies. We discuss how this method could be further refined including adapting the method to robotic sample processing.


Assuntos
Brassica napus/genética , DNA de Plantas/genética , Ensaios de Triagem em Larga Escala/métodos , Ploidias , Brassica napus/citologia , Núcleo Celular/metabolismo , Citometria de Fluxo/métodos , Fluorescência , Células Germinativas Vegetais/metabolismo , Propídio/metabolismo
13.
J Stomatol Oral Maxillofac Surg ; 118(3): 161-166, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28400319

RESUMO

Many techniques have been described to prevent the appearance and relapse of keloids but most of them have an efficacy lower than 50%. Our objective is to describe our standardized management of keloids by associated surgery and brachytherapy. Surgery-brachytherapy is usually given only when less invasive treatments failed. Both a surgeon and a radiotherapist are involved. Forty-eight hours of hospitalization in a surgery unit are required. The extra-lesional excision is performed and a brachytherapy sheath is placed in the dermis plane. An iridium source with an initial activity of 300 GBq is used to deliver high dose rate brachytherapy. The brachytherapy sessions are held in a lead-shielded room in a radiotherapy unit: the first session at 6 h after surgical excision, while the second and third on the following day. The total dose administered is 18 Gy. A surgical workup is scheduled at 10 days. The patient is followed-up closely by the radiotherapist for an 18-month period. The recurrence rate after 2 years is 8 to 12%. The main complaints are dyschromia, telangiectasia and skin atrophy.


Assuntos
Braquiterapia , Queloide/radioterapia , Queloide/cirurgia , Braquiterapia/métodos , Terapia Combinada , Face/cirurgia , Humanos , Queloide/patologia , Dosagem Radioterapêutica , Radioterapia Adjuvante , Procedimentos de Cirurgia Plástica/métodos , Recidiva , Resultado do Tratamento
14.
Eur Arch Paediatr Dent ; 18(1): 51-58, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-28083823

RESUMO

AIMS: To assess via a questionnaire the changes in knowledge and prescription habits for systemic fluoride of physicians at maternal and infant protection centres (MIP) and paediatricians in private practice (PPP) in the Brittany region between 2003 and 2014. METHODS: In both 2003 and 2014, the same seven-question survey was mailed to PPP (110 in 2003 and 101 in 2014) and MIP (61 in 2003 and 71 in 2014). An eighth question was added in 2014 about French guidelines published in 2008 (AFSSAPS guidelines). RESULTS: The overall response rate was significantly higher in 2003 (69.0%) than in 2014 (54.7%). In 2014 systemic fluoride was still considered an effective means of caries prevention (79.8% vs. 98.7% in 2003) and systematic prescription of fluoride supplements was less common (39.4 vs. 87.0% in 2003). When prescribed, systemic fluoride was given after the first 6 months of a child's life in 2014 (79.8%) instead of within the first month of life (73.5%) in 2003. CONCLUSIONS: Paediatricians and MIP physicians in Brittany were significantly less prone to routinely prescribe systemic fluoride in 2014. Certain sources of fluoride were still not well known in 2014. Collaboration and information sharing between dentists and physicians is necessary.


Assuntos
Atitude do Pessoal de Saúde , Cárie Dentária/prevenção & controle , Fluoretos/uso terapêutico , Padrões de Prática Médica/tendências , Administração Oral , França , Fidelidade a Diretrizes , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Pediatras , Guias de Prática Clínica como Assunto , Inquéritos e Questionários
15.
J Geophys Res Planets ; 122(12): 2510-2543, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-29497589

RESUMO

The Mars Science Laboratory Curiosity rover performed coordinated measurements to examine the textures and compositions of aeolian sands in the active Bagnold dune field. The Bagnold sands are rounded to subrounded, very fine to medium sized (~45-500 µm) with ≥6 distinct grain colors. In contrast to sands examined by Curiosity in a dust-covered, inactive bedform called Rocknest and soils at other landing sites, Bagnold sands are darker, less red, better sorted, have fewer silt-sized or smaller grains, and show no evidence for cohesion. Nevertheless, Bagnold mineralogy and Rocknest mineralogy are similar with plagioclase, olivine, and pyroxenes in similar proportions comprising >90% of crystalline phases, along with a substantial amorphous component (35% ± 15%). Yet Bagnold and Rocknest bulk chemistry differ. Bagnold sands are Si enriched relative to other soils at Gale crater, and H2O, S, and Cl are lower relative to all previously measured Martian soils and most Gale crater rocks. Mg, Ni, Fe, and Mn are enriched in the coarse-sieved fraction of Bagnold sands, corroborated by visible/near-infrared spectra that suggest enrichment of olivine. Collectively, patterns in major element chemistry and volatile release data indicate two distinctive volatile reservoirs in Martian soils: (1) amorphous components in the sand-sized fraction (represented by Bagnold) that are Si-enriched, hydroxylated alteration products and/or H2O- or OH-bearing impact or volcanic glasses and (2) amorphous components in the fine fraction (<40 µm; represented by Rocknest and other bright soils) that are Fe, S, and Cl enriched with low Si and adsorbed and structural H2O.

16.
Eur Arch Paediatr Dent ; 16(6): 477-81, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26253277

RESUMO

AIM: To assess retrospectively the efficacy of computer-assisted intraosseous anaesthesia (CAIO) in children using an anaesthetic solution with a lower concentration of epinephrine (1:400,000). METHODS: In a retrospective study, CAIO was evaluated in healthy children and adolescents for restorative and endodontic treatments, uncomplicated tooth extractions or scalings using articaine 4 % plus epinephrine 1:400,000. Anaesthesia was performed in children who showed enough compliance (score of 0-3 according to modified behaviour Venham scale). Efficacy, amount of anaesthetic solution as well as need of a complementary injection was assessed. RESULTS: A total of 421 consecutive sessions were performed on 278 patients aged 7.1 ± 2.9 years with 518 teeth involved in the anaesthetic process and analysed process. When teeth to be anaesthetised were considered, the overall success rate was 97.2 %. In most of the cases, only 0.9 mL was needed to achieve anaesthesia. Permanent teeth needed significantly more anaesthetics than primary teeth. Sensitivity of the teeth anaesthetized reappeared in 5.7 % of cases after 30-60 min of treatment. CONCLUSIONS: These results suggest that CAIO with 4 % articaine and epinephrine diluted 1:400,000 can be an alternative to usual infiltration techniques or IO with epinephrine at a higher concentration for most of treatments in primary and permanent teeth. Further studies are needed to evaluate its efficacy in permanent teeth in case of endodontic treatment or extraction.


Assuntos
Anestesia Dentária/métodos , Anestésicos Locais/administração & dosagem , Carticaína/administração & dosagem , Epinefrina/administração & dosagem , Terapia Assistida por Computador , Vasoconstritores/administração & dosagem , Adolescente , Processo Alveolar , Anestesia Dentária/instrumentação , Anestesia Local/instrumentação , Anestesia Local/métodos , Criança , Pré-Escolar , Capeamento da Polpa Dentária/métodos , Restauração Dentária Permanente/métodos , Feminino , Seguimentos , Humanos , Injeções/instrumentação , Injeções/métodos , Masculino , Agulhas , Pulpotomia/métodos , Estudos Retrospectivos , Extração Dentária/métodos , Dente Decíduo/efeitos dos fármacos , Resultado do Tratamento
17.
Invest Radiol ; 22(8): 688-92, 1987 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-3667176

RESUMO

Numerous eyeglass lens materials have been recommended for protection of radiologists' eyes from the cataractogenic effect of radiation during fluoroscopic procedures. For the most part, these lenses coincidentally attenuate x-ray beams because they contain elements of high atomic number that are added to increase refractive index. With a bean hardened to simulate scatter, direct transmission ratios were measured for 32 commercially available lens materials. Scatter to the eye, both through and around the glass lenses and secondary scatter to the eye from the radiologist's head, was determined with lenses mounted on a head phantom and a 1-cm3 ion chamber in the position of the eye. Transmission ratios for the various lenses ranged from 3% to 98% for an 80 kVp x-ray beam (HVL = 4.5 mm Al). Measurements with the head phantom in place show that secondarily scattered radiation from the fluoroscopist's head contributes significantly to ocular exposure. Optimal radiation protection of the eyes during fluoroscopy depends not only on eyeglasses with leaded glass, but also on shielding of sufficient size and shape to reduce exposure to the surrounding head.


Assuntos
Catarata/prevenção & controle , Dispositivos de Proteção dos Olhos/normas , Fluoroscopia , Doenças Profissionais/prevenção & controle , Equipamentos de Proteção/normas , Proteção Radiológica/instrumentação , Humanos , Modelos Estruturais , Doses de Radiação , Espalhamento de Radiação
18.
J Radiol ; 81(5): 538-41, 2000 May.
Artigo em Francês | MEDLINE | ID: mdl-10804404

RESUMO

In the differential diagnosis of colonic obstruction, the endometriosis is an uncommon disease, rarely reported. The endometriosis of the bowel should be suspected on young women with a history of colonic symptoms and gynecologic complaints. The preoperative diagnosis is difficult, based on the clinical history, the imaging modalities and the endoscopic explorations.


Assuntos
Endometriose/complicações , Obstrução Intestinal/etiologia , Adulto , Endometriose/diagnóstico por imagem , Feminino , Humanos , Obstrução Intestinal/diagnóstico por imagem , Radiografia
19.
Science ; 343(6169): 1244734, 2014 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-24324274

RESUMO

Sedimentary rocks examined by the Curiosity rover at Yellowknife Bay, Mars, were derived from sources that evolved from an approximately average martian crustal composition to one influenced by alkaline basalts. No evidence of chemical weathering is preserved, indicating arid, possibly cold, paleoclimates and rapid erosion and deposition. The absence of predicted geochemical variations indicates that magnetite and phyllosilicates formed by diagenesis under low-temperature, circumneutral pH, rock-dominated aqueous conditions. Analyses of diagenetic features (including concretions, raised ridges, and fractures) at high spatial resolution indicate that they are composed of iron- and halogen-rich components, magnesium-iron-chlorine-rich components, and hydrated calcium sulfates, respectively. Composition of a cross-cutting dike-like feature is consistent with sedimentary intrusion. The geochemistry of these sedimentary rocks provides further evidence for diverse depositional and diagenetic sedimentary environments during the early history of Mars.


Assuntos
Exobiologia , Meio Ambiente Extraterreno/química , Sedimentos Geológicos/química , Marte , Baías , Sulfato de Cálcio/análise , Sulfato de Cálcio/química , Cloro/análise , Cloro/química , Óxido Ferroso-Férrico/análise , Óxido Ferroso-Férrico/química , Halogênios/análise , Halogênios/química , Concentração de Íons de Hidrogênio , Ferro/análise , Ferro/química , Magnésio/análise , Magnésio/química , Silicatos/análise , Silicatos/química , Água/química
20.
Science ; 341(6153): 1239463, 2013 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-24072927

RESUMO

"Jake_M," the first rock analyzed by the Alpha Particle X-ray Spectrometer instrument on the Curiosity rover, differs substantially in chemical composition from other known martian igneous rocks: It is alkaline (>15% normative nepheline) and relatively fractionated. Jake_M is compositionally similar to terrestrial mugearites, a rock type typically found at ocean islands and continental rifts. By analogy with these comparable terrestrial rocks, Jake_M could have been produced by extensive fractional crystallization of a primary alkaline or transitional magma at elevated pressure, with or without elevated water contents. The discovery of Jake_M suggests that alkaline magmas may be more abundant on Mars than on Earth and that Curiosity could encounter even more fractionated alkaline rocks (for example, phonolites and trachytes).

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