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1.
Pol J Vet Sci ; 26(4): 635-646, 2023 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-38088307

RESUMO

Airway remodeling is a major pathological characteristic of chronic obstructive pulmonary disease (COPD). This study aimed to investigate the effect of Abhd2 deficiency on ovalbumin (OVA)-induced airway remodeling and inflammation in vivo. Abhd2-deficient mice were used to establish an OVA-induced asthma model. Lung tissues were analyzed using hematoxylin and eosin (HE) staining, Masson staining, immunohistochemistry, quantitative reverse transcription- polymerase chain reaction (qRT-PCR), and western blotting were used to determine the role of Abhd2 in the regulation of OVA-induced airway remodeling and inflammation. Our findings revealed that the RNA expression of inflammatory factors, including IL-1ß, IL-6, IL-4, and IL-13, was significantly increased in OVA-induced Abhd2 Gt/Gt asthmatic mice. The expression of IFN-γ was decreased significantly in OVA-induced Abhd2 Gt/Gt asthmatic mice. The protein expression of airway remodeling factors, including α-SMA, type I collagen, and Ki67, was also increased in OVA-induced Abhd2 Gt/Gt asthmatic mice compared to that in OVA-induced wild-type (WT) mice. Additionally, Abhd2 deficiency promoted the expression of p-Akt in tissues of the asthma model. These results suggest that Abhd2 deficiency exacerbates airway remodeling and inflammation through the PI3K/Akt pathway in chronic asthma.


Assuntos
Asma , Animais , Camundongos , Remodelação das Vias Aéreas , Asma/induzido quimicamente , Asma/genética , Asma/veterinária , Líquido da Lavagem Broncoalveolar , Modelos Animais de Doenças , Inflamação/metabolismo , Inflamação/veterinária , Pulmão , Camundongos Endogâmicos BALB C , Ovalbumina/toxicidade , Ovalbumina/metabolismo , Fosfatidilinositol 3-Quinases/genética , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo
2.
Eur Rev Med Pharmacol Sci ; 27(12): 5397-5409, 2023 06.
Artigo em Inglês | MEDLINE | ID: mdl-37401274

RESUMO

OBJECTIVE: Adult stem cell senescence and exhaustion are important drivers of organismal age. Restored stem cell self-renewal has revealed novel therapeutic targets for decreasing the incidence of age-associated diseases (AADs) and prolonging the human health span. Transient ectopic expression of the reprogramming factors Oct3/4, Sox2, Klf4 and c-Myc (collectively known as OSKM) in somatic cells can induce partial cellular reprogramming and effectively ameliorate their age-associated hallmarks. However, how this form of rejuvenation is applied to senescent stem cells remains unknown. MATERIALS AND METHODS: The Integrin-α6highCD71high epidermal stem cells (ESCs) with low self-renewal ability were sorted by flow cytometry and then treated by the interrupted reprogramming induced by transient expression of OSKM. The ability of secondary clones' generation and self-proliferation in vitro, as well as stem cell marker p63, were detected to determine their self-renewal ability. Besides, gene and protein of epidermal cell markers were detected to determine whether their cell identities were retained. Finally, DNA methylation age (eAge) and DNA dehydroxymethylase/methyltransferase were analyzed to explore the alternation of their global DNA methylation pattern during this rejuvenation. RESULTS: The partial reprogramming restored the youthful self-renewal and proliferation in senescent ESCs, including larger secondary clone generation, higher expression of stem cell marker p63 and proliferation marker Ki67, and faster proliferation speed, in each case without abolishing epithelial cellular identity. Moreover, the rejuvenation of adult stem cells could be maintained for 2 weeks after reprogramming factor withdrawal, which was more stable than that of differentiated somatic cells. Additionally, we found that partial reprogramming counteracted the acceleration of eAge in senescent epidermal stem cells and DNA methyltransferase 1 (DNMT1) may play a crucial role in this process. CONCLUSIONS: Partial reprogramming has high therapeutic potential for reversing adult stem cell age, providing an advanced way to treat AADs.


Assuntos
Reprogramação Celular , Células-Tronco Pluripotentes Induzidas , Adulto , Humanos , Células-Tronco , Células Epidérmicas , Metiltransferases/metabolismo , DNA/metabolismo , Células-Tronco Pluripotentes Induzidas/metabolismo
3.
Zhonghua Wai Ke Za Zhi ; 61(5): 431-436, 2023 Mar 29.
Artigo em Chinês | MEDLINE | ID: mdl-36987677

RESUMO

In recent years, laparoscopic surgery and robotic surgery have been widely used, and various intraoperative image navigation systems have also developed rapidly. However, the liver itself has a complex vessel and duct system, which increase the difficulty of liver surgery. The augmented reality image navigation system combines the three-dimensional reconstructed image of the liver with the real liver anatomy, which presents the specific relationship between the tumor location and the surrounding vessels for the surgeon. Compared with other intraoperative image navigation methods, augmented reality has its unique advantages. This paper provides an overview of current advances in registration technology in augmented reality image navigation system, and focuses on its applications in liver surgery, including laparoscopic surgery and robotic surgery. Finally, the technological problems and difficulties still faced at present are summarized, and future directions worth studying in this field are proposed.

4.
J Endocrinol Invest ; 45(12): 2341-2351, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-35908009

RESUMO

BACKGROUND: The prognosis of biliary neuroendocrine neoplasms (NENs) patients is affected by the status of metastatic lymph nodes. The purpose of this study was to explore the prognostic value of the log odds of positive lymph nodes (LODDS) and develop a novel nomogram to predict the overall survival (OS) in biliary NENs patients. METHODS: A total of 125 patients with histologically confirmed biliary NENs were selected from the Surveillance, Epidemiology and End Results (SEER) database and further divided into training and validation cohorts. The discrimination and calibration of the nomogram were evaluated using the concordance index (C-index), the area under the time-dependent receiver operating characteristic curve (time-dependent AUC), and calibration plots. The net benefits and clinical utility of the nomogram were quantified and compared with those of the SEER staging system using decision curve analysis (DCA), net reclassification index (NRI), and integrated discrimination improvement (IDI). The risk stratifications of the nomogram and the SEER staging system were compared. RESULTS: LODDS showed the highest accuracy in predicting OS for biliary NENs. The C-index (0.789 for the training cohort and 0.890 for the validation cohort) and the time-dependent AUC (> 0.7) indicated the satisfactory discriminative ability of the nomogram. The calibration plots showed a high degree of consistency. The DCA, NRI, and IDI indicated that the nomogram performed significantly better than the SEER staging system. CONCLUSION: A novel LODDS-incorporated nomogram was developed and validated to assist clinicians in evaluating the prognosis of biliary NENs patients.


Assuntos
Tumores Neuroendócrinos , Nomogramas , Humanos , Prognóstico , Linfonodos/cirurgia , Linfonodos/patologia , Curva ROC , Tumores Neuroendócrinos/cirurgia , Tumores Neuroendócrinos/patologia , Estadiamento de Neoplasias
6.
Zhonghua Yi Xue Za Zhi ; 99(48): 3797-3802, 2019 Dec 24.
Artigo em Chinês | MEDLINE | ID: mdl-31874517

RESUMO

Objective: To explore the clinical efficacy of damage control orthopaedics in treatment of patients with severe traumatic brain injury combined with limb fracture. Methods: Total 149 patients with sTBI combined with limb fracture treated in Emergency Surgery Department of Shandong University Qilu Hospital from January, 2011 to December, 2018 were collected. Patients that were treated with immediate definitive fixation before March 31st, 2013 were included into the routine treatment group (group A, 47 cases), and that were treated with damage control orthopaedics (DCO) after April 1st, 2013 were included into the DCO group (group B, 102 cases). The clinical data during hospitalization and prognosis 3 months after injury was analyzed retrospectively. Then according to the risk of postoperative ICP increase, the two groups were divided into low risk subgroup and high risk subgroup. The postoperative ICP, length of stay and GOS score were statistically analyzed. Results: There were no statistically significant differences in sex, age, preoperative GCS score, imaging type of lesion and initial intraoperative ICP between the two groups. The postoperative ICP and incidence of coagulation dysfunction were significantly higher in group A [(17.1±4.6) mmHg, 29.8%] than that in group B[(15.0±4.3) mmHg, 13.7%] separately(P<0.05), and there was no significant difference of length of stay and GOS score between the two groups (P=0.475 and 0.097, respectively). As for the subgroup with low risk of postoperative ICP increase, there was no significant difference in postoperative ICP and GOS score between group A and B, and the length of stay of group B was significantly longer than that of group A (P<0.05). As for the subgroup with high risk of postoperative ICP increase, there was no significant difference in the length of stay between group A and B (P=0.667), and for group A the postoperative ICP was higher and GOS score was lower than that of group B (P<0.05). Conclusions: For patients with sTBI combined with limb fracture, the application of DCO should be based on the severity of traumatic brain injury. For patients with high risk of postoperative ICP increase, DCO can significantly improve the prognosis of patients.


Assuntos
Lesões Encefálicas Traumáticas , Ortopedia , Humanos , Pressão Intracraniana , Tempo de Internação , Estudos Retrospectivos , Resultado do Tratamento
7.
Plant Biol (Stuttg) ; 21(1): 25-34, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30101415

RESUMO

Plants have evolved a sophisticated two-branch defence system to prevent the growth and spread of pathogen infection. The novel Cys-rich repeat (CRR) containing receptor-like kinases, known as CRKs, were reported to mediate defence resistance in plants. For rice, there are only two reports of CRKs. A semi-dominant lesion mimic mutant als1 (apoptosis leaf and sheath 1) in rice was identified to demonstrate spontaneous lesions on the leaf blade and sheath. A map-based cloning strategy was used for fine mapping and cloning of ALS1, which was confirmed to be a typical CRK in rice. Functional studies of ALS1 were conducted, including phylogenetic analysis, expression analysis, subcellular location and blast resistance identification. Most pathogenesis-related (PR) genes and other defence-related genes were activated and up-regulated to a high degree. ALS1 was expressed mainly in the leaf blade and sheath, in which further study revealed that ALS1 was present in the vascular bundles. ALS1 was located in the cell membrane of rice protoplasts, and its mutation did not change its subcellular location. Jasmonic acid (JA) and salicylic acid (SA) accumulation were observed in als1, and enhanced blast resistance was also observed. The mutation of ALS1 caused a constitutively activated defence response in als1. The results of our study imply that ALS1 participates in a defence response resembling the common SA-, JA- and NH1-mediated defence responses in rice.


Assuntos
Genes Dominantes , Genes de Plantas , Mutação/genética , Oryza/enzimologia , Oryza/genética , Proteínas de Plantas/genética , Proteínas Serina-Treonina Quinases/genética , Sequência de Aminoácidos , Ciclopentanos/farmacologia , Resistência à Doença , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Oryza/efeitos dos fármacos , Oxilipinas/farmacologia , Fenótipo , Doenças das Plantas/microbiologia , Folhas de Planta/metabolismo , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Proteínas Serina-Treonina Quinases/química , Proteínas Serina-Treonina Quinases/metabolismo , Ácido Salicílico/farmacologia
8.
Zhonghua Wai Ke Za Zhi ; 55(11): 838-841, 2017 Nov 01.
Artigo em Chinês | MEDLINE | ID: mdl-29136731

RESUMO

Objective: To explore the safety and feasibility of associating diaphragm resection and liver-diaphragmatic metastasis lesions resection for patients with advanced ovarian cancer. Methods: Retrospectively analysis 83 cases(98 times) of advanced ovarian cancer with liver-diaphragmatic metastasis between January 2012 and December 2016 at Department of Liver Surgery, Peking Union Medical College Hospital.The patients were aged from 19 to 75 years.Surgical procedure included metastatic lesions resection(43 times) and stripping(55 times). Operation status, post-operative complications, pathology results and follow-up of the patients were analyzed. Results: Fifteen patients received twice surgical treatment and 68 patients received one time surgical treatment. Postoperative hemorrhage in chest and between liver and diaphragm was not occurred in all cases.Dyspnea and low oxygen saturation were occurred in two cases of stripping patients and 1 case of metastatic lesions resection patients.Results of CT examination indicated that there was medium to large amount of ascites in right chests.The symptoms were relieved after placing thoracic closed drainage.Other patients were recovered smoothly.All patients were diagnosed as ovarian cancer by pathological examination. Conclusion: Associating diaphragm resection is safe and feasible for liver-diaphragmatic metastasis lesions from ovarian cancer.


Assuntos
Diafragma/cirurgia , Neoplasias Hepáticas/cirurgia , Neoplasias Epiteliais e Glandulares/cirurgia , Neoplasias Ovarianas/cirurgia , Adulto , Idoso , Carcinoma Epitelial do Ovário , Feminino , Humanos , Fígado , Neoplasias Hepáticas/secundário , Pessoa de Meia-Idade , Neoplasias Epiteliais e Glandulares/patologia , Neoplasias Ovarianas/patologia , Estudos Retrospectivos , Adulto Jovem
9.
Rev Sci Instrum ; 88(8): 083501, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28863682

RESUMO

The ThermoElectric-driven Liquid-metal plasma-facing Structures (TELS) experiment at the University of Illinois is a gas-puff driven, theta-pinch plasma source that is used as a test stand for off-normal plasma events incident on materials in the edge and divertor regions of a tokamak. The ion temperatures and resulting energy distributions are crucial for understanding how well a TELS pulse can simulate an extreme event in a larger, magnetic confinement device. A retarding field energy analyzer (RFEA) has been constructed for use with such a transient plasma due to its inexpensive and robust nature. The innovation surrounding the use of a control analyzer in conjunction with an actively sampling analyzer is presented and the conditions of RFEA operation are discussed, with results presented demonstrating successful performance under extreme conditions. Such extreme conditions are defined by heat fluxes on the order of 0.8 GW m-2 and on time scales of nearly 200 µs. Measurements from the RFEA indicate two primary features for a typical TELS discharge, following closely with the pre-ionizing coaxial gun discharge characteristics. For the case using the pre-ionization pulse (PiP) and the theta pinch, the measured ion signal showed an ion temperature of 23.3 ± 6.6 eV for the first peak and 17.6 ± 1.9 eV for the second peak. For the case using only the PiP, the measured signal showed an ion temperature of 7.9 ± 1.1 eV for the first peak and 6.6 ± 0.8 eV for the second peak. These differences illustrate the effectiveness of the theta pinch for imparting energy on the ions. This information also highlights the importance of TELS as being one of the few linear pulsed plasma sources whereby moderately energetic ions will strike targets without the need for sample biasing.

10.
Opt Express ; 24(20): 23519-23530, 2016 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-27828414

RESUMO

A profile preferentially partial occlusion removal method for integral imaging is presented. The profile of the occlusion always contains details with significant texture structure, and regions with significant texture structure often lead to reliable depth estimation. Taking the advantage of the significant texture structure, the profile of occlusion is preferentially dealt with, and then the entire occlusion region is determined via regional spreading according to the accurate profile. The details of occlusion can be accurately removed and the occluded scene is also retained to the maximum degree. In our method, elemental images are integrated into a four-dimensional light field to provide consistently reliable depth estimation and occlusion decisions among all elemental images. Experimental results show that the proposed method is efficient to deal with the details of the occlusion, and it is robust for the occlusions with different kinds of texture structure.

11.
Ultramicroscopy ; 171: 1-7, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27584051

RESUMO

Here we report the influence of key experimental parameters on atomically resolved energy dispersive X-ray spectroscopy (EDX). In particular, we examine the role of the probe forming convergence semi-angle, sample thickness, lattice spacing, and dwell/collection time. We show that an optimum specimen-dependent probe forming convergence angle exists to maximize the signal-to-noise ratio of the atomically resolved signal in EDX mapping. Furthermore, we highlight that it can be important to select an appropriate dwell time to efficiently process the X-ray signal. These practical considerations provide insight for experimental parameters in atomic resolution energy dispersive X-ray analysis.

12.
Genet Mol Res ; 15(2)2016 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-27323090

RESUMO

The identification of simple sequence repeat (SSR) markers associated with salt tolerance in cotton contributes to molecular assisted selection (MAS), which can improve the efficiency of traditional breeding. In this study, 134 samples of upland cotton cultivars were selected. The seedling emergence rates were tested under 0.3% NaCl stress. A total of 74 SSR markers were used to scan the genomes of these samples. To identify SSR markers associated with salt tolerance, an association analysis was performed between salt tolerance and SSR markers using TASSEL 2.1, based on the analysis of genetic structure using Structure 2.3.4. The results showed that the seedling emergence rates of 134 cultivars were significantly different, and 27 salt-sensitive and 10 salt-tolerant cultivars were identified. A total of 148 loci were found in 74 SSR markers involving 246 allelic variations, which ranged from 2 to 7 with an average of 3.32 per SSR marker. The gene diversity ranged from 0.0295 to 0.4959, with the average being 0.2897. The polymorphic information content ranged from0.0290 to 0.3729, with the average being 0.2381. This natural population was classified into two subgroups by Structure 2.3.4, containing 89 and 45 samples, respectively. Finally, eight SSR sites associated with salt tolerance ware found through an association analysis, with the rate of explanation ranging from 2.91 to 7.82% and an average of 4.32%. These results provide reference data for the use MAS for salt tolerance in cotton.


Assuntos
Gossypium/genética , Repetições de Microssatélites/genética , Tolerância ao Sal/genética , Alelos , Cruzamento , Mapeamento Cromossômico , Estudos de Associação Genética , Variação Genética , Gossypium/crescimento & desenvolvimento , Fenótipo , Locos de Características Quantitativas/genética
13.
Ultramicroscopy ; 168: 7-16, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27258645

RESUMO

Quantitative agreement on an absolute scale is demonstrated between experiment and simulation for two-dimensional, atomic-resolution elemental mapping via energy dispersive X-ray spectroscopy. This requires all experimental parameters to be carefully characterized. The agreement is good, but some discrepancies remain. The most likely contributing factors are identified and discussed. Previous predictions that increasing the probe forming aperture helps to suppress the channelling enhancement in the average signal are confirmed experimentally. It is emphasized that simple column-by-column analysis requires a choice of sample thickness that compromises between being thick enough to yield a good signal-to-noise ratio while being thin enough that the overwhelming majority of the EDX signal derives from the column on which the probe is placed, despite strong electron scattering effects.

14.
Ultramicroscopy ; 164: 51-61, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26948674

RESUMO

Here we report a numerical approach to model a four quadrant energy dispersive X-ray spectrometer in the transmission electron microscope. The model includes detector geometries, specimen position and absorption, shadowing by the holder, and filtering by the Be carrier. We show that this comprehensive model accurately predicts absolute counts and intensity ratios as a function of specimen tilt and position. We directly compare the model to experimental results acquired with a FEI Super-X EDS four quadrant detector. The contribution from each detector to the sum is investigated. The program and source code can be downloaded from https://github.com/subangstrom/superAngle.

15.
Genet Mol Res ; 14(4): 13120-30, 2015 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-26535625

RESUMO

Verticillium wilt is one of the main diseases in cotton (Gossypium hirsutum), severely reduces yield and fiber quality, and is difficult to be con-trolled effectively. At present, the molecular mechanism that confers resistance to this disease is unclear. Transcriptome sequencing is an important method to detect resistance genes, explore metabolic pathways, and study resistance mechanisms. In this study, the transcriptome of a disease-resistant inbred cot-ton line inoculated with Verticillium dahliae was sequenced. A total of 126,402 unigenes were obtained using de novo assembly and data analysis, 99,712 (78.88%) of which were annotated into the Nr, Nt, Swiss-Prot, KEGG, COG, and GO databases. The expression patterns of 16 candidate disease-resis-tance genes showed that some genes were upregulated soon after V. dahliae inoculation and others were upregulated later, which may indicate instanta-neous basal defense and lagged specific defense, respectively. We conducted a preliminary analysis of the transcriptome database, which will contribute to further research regarding the cloning of disease-resistance genes.


Assuntos
Gossypium/genética , Gossypium/microbiologia , Transcriptoma , Verticillium , Biologia Computacional , Resistência à Doença/genética , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Gossypium/metabolismo , Interações Hospedeiro-Patógeno/genética , Redes e Vias Metabólicas , Anotação de Sequência Molecular , Doenças das Plantas/genética
16.
Genet Mol Res ; 14(4): 13215-20, 2015 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-26535635

RESUMO

We conducted a case-control study to investigate the association between PAR1 gene polymorphisms and the development of chronic obstructive pulmonary disease (COPD). A total of 270 patients with COPD and 270 control subjects were consecutively recruited between March 2012 and March 2014. A polymerase chain reaction restriction fragment length polymorphism assay was used to assess the polymorphisms PAR1 IVS-14 A/T rs168753 and -506 I/D rs11267092. The frequency of the AA genotype in PAR1 IVS-14 A/T rs168753 was significantly higher than in the controls (χ(2) = 7.23, P = 0.03). By logistic regression analysis, we found that the AA genotype of PAR1 IVS-14 A/T rs168753 was associated with increased risk of COPD compared with the GG genotype. The adjusted OR (95%CI) was 2.00 (1.15-3.50) for the AA genotype. In conclusion, we found that the PAR1 IVS-14 A/T rs168753 polymorphism was associated with the development of COPD.


Assuntos
Predisposição Genética para Doença , Polimorfismo Genético , Doença Pulmonar Obstrutiva Crônica/genética , Receptor PAR-1/genética , Idoso , Alelos , Estudos de Casos e Controles , Feminino , Frequência do Gene , Estudos de Associação Genética , Genótipo , Humanos , Mutação INDEL , Masculino , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único , Fatores de Risco
17.
West Indian Med J ; 64(5): 495-498, 2015 12.
Artigo em Inglês | MEDLINE | ID: mdl-27398727

RESUMO

The numerical simulation model of blood flow in bend is studied in this paper. The curvature modification is conducted for the blood flow model in bend to obtain the modified blood flow model in bend. The modified model is verified by U tube. By comparing the simulation results with the experimental results obtained by measuring the flow data in U tube, it was found that the modified blood flow model in bend can effectively improve the prediction accuracy of blood flow data affected by the curvature effect.

18.
Can J Neurol Sci ; 38(5): 719-22, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21856574

RESUMO

RATIONALE: Few data exist on the frequency and burden of childhood epilepsy in Canada and on the impact in the general population. We have assessed the point prevalence of childhood epilepsy in Canada. METHODS: We analyzed data from the National Longitudinal Survey of Children and Youth (N=20 025 for Cycle 2, and N= 31 960 for cycle 3). Each cycle was collected over a two year period (2: 1996-1997, 3: 1998-1999). In the survey the following specific question was asked to the person most knowledgeable in the household: "Does the child have any of the following long-term conditions that have been diagnosed by a health professional?" The list of responses included Epilepsy and certain co-morbid conditions. In addition, a subsequent question identified whether the condition was treated by means of a specific anticonvulsant medication. (anticonvulsants or anti-epileptic pills?). Prevalence was based on the national standard population at the time of each survey. RESULTS: In Cycle 2, 80 of 20 025 subjects from 0 to 13 years old were described to have the diagnosis of epilepsy, yielding a weighted point prevalence of 4.03 per 1 000. In Cycle 3 161 of 31 960 children from 0 to 15 were described as having epilepsy, yielding a weighted point prevalence of 5.26 per 1 000. The rate of epilepsy was higher for males and increases with age. CONCLUSION: The overall rates for this age cohort are consistent with those obtained in other developed countries and seem to coincide with rates for youth and adults in Canada.


Assuntos
Epilepsia/epidemiologia , Adolescente , Canadá/epidemiologia , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Recém-Nascido , Estudos Longitudinais , Masculino , Prevalência , Estudos Retrospectivos
19.
Acta Crystallogr A ; 66(Pt 6): 685-93, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-20962378

RESUMO

Debye-Waller (DW) factors and structure factors have been measured for Si using convergent-beam electron diffraction (CBED) experiments with a transmission electron microscope equipped with a field-emission gun and a post-column energy-filtering device. Si has been used here to evaluate the accuracy of multi-beam near-zone-axis orientations for the simultaneous refinement of DW factors and multiple structure factors. Strong dynamic interactions among different beams are obtained by tilting the crystal to specific four- or six-beam orientations near major zone axes, which provide sufficient sensitivity to determine accurate DW factors and structure factors. The DW factors of Si were measured using four-beam conditions near the [001] zone axis for temperatures ranging from 96 to 300 K. A comparison of the multi-beam near-zone-axis orientations with other CBED methods for DW and structure factor F(g) refinement is presented.

20.
Acta Crystallogr A ; 66(Pt 6): 694-702, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-20962379

RESUMO

Accurate Debye-Waller (DW) factors and several low-index structure factors of chemically ordered ß-NiAl at different temperatures have been measured using an off-zone-axis multi-beam convergent-beam electron diffraction method. The temperature dependences of DW factors of Ni and Al atoms are compared with previous experimental measurements and theoretical calculations. The temperature below which the DW factor of Ni becomes smaller than that of Al was found to be lower than previously reported. Structure factors are determined with an accuracy of 0.05% and compared with prior reports.

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