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1.
Front Sports Act Living ; 5: 1096272, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37139305

RESUMO

Introduction: The Mixed-Team-Relay (MTR) triathlon is an original race format present on the international scene since 2009, which became an Olympic event at the Tokyo 2020 Games. The aim of this study was to define the probabilities of reaching a victory, a podium, or a finalist rank in a relay triathlon, according to the position of any of the four relayers (Women/Men/Women/Men) during each of the four segments (leg) of the race. Methods: All MTR results from the World Series, Continental Championships, World Championships from 2009 to 2021 and Tokyo 2020 Olympics have been collected. We calculated the set of probability frequencies of reaching a given final state, according to any transient state during the race. All results are compared with a V' Cramer method. Results: The frequency of winning is similar at the end of Leg 1 for TOP1 (first position) and TOP2-3 (second and third positions). Then, a difference in the winning-associated frequencies is first observed after the Bike stage of Leg 2, where 47% of TOP1 athletes will win, vs 13% of the TOP2-3. Discussion: This difference continually increases until the end of the race. Legs 2 and 3 are preponderant on the outcome of the race, the position obtained by each triathlete, especially in swimming and cycling, greatly influences the final performance of the team. Leg 1 allows to maintain contact with the head of the race, while Leg 4 sets in stone the position obtained by the rest of the team.

3.
Phys Rev Lett ; 123(21): 217201, 2019 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-31809154

RESUMO

While the usual approach to tailor the behavior of condensed matter and nanosized systems is the choice of material or finite-size or interfacial effects, topology alone may be the key. In the context of the motion of magnetic domain walls (DWs), known to suffer from dynamic instabilities with low mobilities, we report unprecedented velocities >600 m/s for DWs driven by spin-transfer torques in cylindrical nanowires made of a standard ferromagnetic material. The reason is the robust stabilization of a DW type with a specific topology by the Œrsted field associated with the current. This opens the route to the realization of predicted new physics, such as the strong coupling of DWs with spin waves above >600 m/s.

4.
Sci Rep ; 9(1): 5130, 2019 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-30914661

RESUMO

Domain wall propagation in modulated-diameter cylindrical nanowires is a key phenomenon to be studied with a view to designing three-dimensional magnetic memory devices. This paper presents a theoretical study of transverse domain wall behavior under the influence of a magnetic field within a cylindrical nanowire with diameter modulations. In particular, domain wall pinning close to the diameter modulation was quantified, both numerically, using finite element micromagnetic simulations, and analytically. Qualitative analytical model for gently sloping modulations resulted in a simple scaling law which may be useful to guide nanowire design when analyzing experiments. It shows that the domain wall depinning field value is proportional to the modulation slope.

5.
Int J Sports Physiol Perform ; 14(2): 183-189, 2019 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-30040002

RESUMO

PURPOSE: To quantify the impact of a polarized distribution of training intensity on performance and fatigue in elite swimmers. METHODS: Twenty-two elite junior swimmers (12 males, age = 17 [3] y, and 10 females, age = 17 [3] y) participated in a crossover intervention study over 28 wk involving 2- × 6-wk training periods separated by 6 wk. Swimmers were randomly assigned to a training group for the first period: polarized (81% in zone 1, blood lactate concentration, [La]b ≤ 2 mmol·L-1; 4% in zone 2, 2 mmol·L-1 < [La]b ≤ 4 mmol·L-1; and 15% in zone 3, [La]b > 4 mmol·L-1) or threshold (65%/25%/10%). Before and after each period, they performed a 100-m maximal swimming test to determine performance, maximal [La]b, and oxygen consumption and an incremental swimming test to determine speed corresponding to [La]b = 4 mmol·L-1 (V4 mmol·L-1). Self-reported indices of well-being were collected with a daily questionnaire. RESULTS: Polarized training elicited small to moderately greater improvement than threshold training on 100-m performance (within-group change ± 90% confidence interval: 0.97% ± 1.02% vs 0.09% ± 0.94%, respectively) with less fatigue and better quality of recovery. There was no substantial gender effect. No clear differences were observed in physiological adaptations between groups. CONCLUSIONS: In elite junior swimmers, a 6-wk period of polarized training induced small improvements in 100-m time-trial performance and, in combination with less perceived fatigue, forms a viable option for coaches preparing such cohorts of swimmers for competition.


Assuntos
Desempenho Atlético/fisiologia , Fadiga , Condicionamento Físico Humano/métodos , Natação/fisiologia , Adaptação Fisiológica , Adolescente , Atletas , Estudos Cross-Over , Feminino , Humanos , Ácido Láctico/sangue , Masculino , Consumo de Oxigênio , Adulto Jovem
6.
J Phys Condens Matter ; 30(28): 285802, 2018 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-29869990

RESUMO

We present here a quantitative analysis of the ground state and magnetic properties of Ce3Pt23Si11, based on a crystalline electric field description within the mean-field approximation. In this face-centered cubic compound, the point group symmetry at the Ce site is orthorhombic. One main difficulty in this low symmetry case is that the CEF potential for Ce3+ ions is determined by five independent parameters, while only two magnetic excitations are observed by inelastic neutron scattering. Moreover the anisotropy of the magnetic susceptibility of the Ce ion, that permits an independent determination of the second-order CEF parameters is hidden by the cubic symmetry of the compound. A specific procedure is developed for this purpose that combines genetic algorithms and more conventional optimization methods. A set of CEF parameters is found that best reproduces the different experimental observations in both the paramagnetic and ferromagnetic phases of Ce3Pt23Si11. The analysis accounts for two seemingly contradictory properties: a strong local anisotropy that aligns the moment along a fourfold axis and a rather weak anisotropy of the bulk magnetization with an easy threefold magnetization axis. Ce3Pt23Si11 is shown to be a model system where single site anisotropies compete within a crystal structure of overall high symmetry.

7.
Rev Sci Instrum ; 89(2): 023304, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29495838

RESUMO

The SEPAGE diagnostic will detect charged particles (electrons, protons, and ions) accelerated in the interaction of the PETAL (PETawatt Aquitaine Laser) laser with its targets on the LMJ (Laser MegaJoule)-PETAL laser facility. SEPAGE will be equipped with a proton-radiography front detector and two Thomson parabolas (TP), corresponding to different ranges of the particle energy spectra: Above 0.1 MeV for electrons and protons in the low-energy channel, with a separation capability between protons and 12C6+ up to 20 MeV proton energy and above 8 MeV for the high-energy channel, with a separation capability between protons and 12C6+ up to 200 MeV proton kinetic energy. This paper presents the calibration of the SEPAGE's low-energy channel TP at the Tandem facility of Orsay (France) with proton beams between 3 and 22 MeV and carbon-ion beams from 5.8 to 84 MeV. The magnetic and electric fields' integrals were determined with an accuracy of 10-3 by combining the deflections measured at different energies with different target thicknesses and materials, providing different in-target energy losses of the beam particles and hence different detected energies for given beam energies.

8.
Ann Burns Fire Disasters ; 31(4): 298-305, 2018 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-30983930

RESUMO

Platelet-rich plasma (PRP) derived from autologous peripheral blood is rich in platelets that release growth factors and cytokines. We determined the effects of topically applied autologous PRP in a partial thickness porcine burn model. Partial thickness burns were created on the backs and flanks of six domestic pigs (24 burns each) using an aluminium bar preheated to 80° C for 20 seconds. After removing the necrotic epidermis, the burns were randomly treated with a topical antibiotic ointment or a single (day 2), double (days 2 and 7), or triple (days 2, 7, and 14) topical application of PRP that was prepared freshly before application. Periodic imaging and full thickness biopsies were conducted to monitor healing over 28 days. The percentage wound reepithelialization at days 11, 14, 18 and 21 did not differ significantly among the groups. By day 28 all wounds were completely (>95%) reepithelialized, and there were no differences among the groups. Time to complete healing (presented as mean, [SD]) did not differ among the groups (antibiotics, 17.1 [3.5]; single PRP, 17.6 [4.0]; double PRP, 18.4 [3.9]; and triple PRP, 17.7 [3.3] days; ANOVA P=0.43). Scar depth (presented as mean, [SD]) in mm at day 28 by treatment group was: antibiotic 5.0 [1.0], single PRP 5.5 [1.1], double PRP 5.4 [1.1], and triple PRP 5.5 [0.6], ANOVA P=0.026. We conclude that PRP results in similar rates of reepithelialization and scar depth to standard topical antibiotics in a partial thickness porcine burn model.


Le plasma riche en plaquettes (PRP), dérivé du sang autologue, permet le relargage de facteurs de croissance et de cytokines. Nous avons étudié l'effet de PRP appliqué localement sur un modèle de brûlure intermédiaire chez le porc. Cette brûlure du dos et des flancs était réalisée au moyen de l'application pendant 20 s d'aluminium chauffé à 80°C sur 4 groupes de 6 porcs. Après ablation de l'escarre, les animaux étaient tirés au sort pour être traités par topique antibiotique, 1 (J2), 2 (J2 et J7) ou 3 (J2, J7, J4) application locale de PRP préparé juste avant utilisation. Des photos et des biopsies ont été réalisées régulièrement pendant 28 j afin de surveiller la cicatrisation. Les pourcentages de surface cicatrisée à J11, J14, J18 et J21 étaient similaires dans tous les groupes. La cicatrisation était quasi complète (> 95%) à J28, dans tous les groupes. Le délai jusqu'à cicatrisation complète n'était pas différent dans les groupes (ANOVA, p=0,43) : Contrôle 17,1 +/- 3,5 ; PRP J2 17,6 +/- 4 ; PRP J2 et J7 18,4 +/- 3,9 ; PRP J4, J7 et J14 17,7 +/- 3,3 jours. La profondeur de la cicatrice, bien que statistiquement significative (ANOVA p = 0,026 ) : 5 +/- 1 (contrôle) ; 5,5 +/- 1,1 (1 PRP) ; 5,4 +/- 1,1 (2 PRP) ; 5,5 +/- 0,6 (3 PRP) mm n'est pas considérée comme cliniquement significative. PRP donne des résultats équivalents aux topiques antibiotiques sur une brûlure intermédiaire du porc.

9.
Rev Mal Respir ; 34(10): 1058-1071, 2017 Dec.
Artigo em Francês | MEDLINE | ID: mdl-29132745

RESUMO

Microparticles (MP) are plasmic membrane fragments released from cells after physiological stimulation or stress conditions like inflammation or infection. Their production is correlated to the rate of cell apoptosis. All types of cells can produce MP but they are produced mainly by platelets, endothelial cells, and leukocytes. They carry many bio-active molecules on their surface, specific to the parental cell, giving them the ability to be biomarkers and bio-effectors. MP are present in circulating blood, tissues and many biological fluids. Circulating MP levels can change during the course of many diseases. They have been the subject of many studies in the fields of cardiovascular disease and oncology. In the lungs, they are present in circulating blood and in the airways. They seem to have a role in pulmonary homeostasis in physiological situations and also in the expression of several disease processes. In this review of the literature, we were interested in the quantitative and qualitative variations in MP and their impact in airway diseases like chronic obstructive pulmonary disease (COPD) and asthma, pulmonary fibrosis and pulmonary hypertension.


Assuntos
Biomarcadores/análise , Micropartículas Derivadas de Células/fisiologia , Transtornos Respiratórios/diagnóstico , Transtornos Respiratórios/etiologia , Biomarcadores/metabolismo , Doenças Cardiovasculares/diagnóstico , Doenças Cardiovasculares/etiologia , Doenças Cardiovasculares/metabolismo , Humanos , Doenças Respiratórias/diagnóstico , Doenças Respiratórias/etiologia , Doenças Respiratórias/metabolismo
10.
Int J Sports Med ; 37(13): 1032-1037, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27676148

RESUMO

The present study focused on rapid responses of inflammation markers and insulin resistance to dietary restriction and exercise in inactive patients. 13 obese women were included during a 5-day time frame during which decreases in food intake (-1 378±298 kcal) were associated with 2 exercise sessions (80 and 40 min). Circulating inflammatory biomarkers, insulin resistance index and muscle soreness were measured in fasted conditions. Fasting plasma concentrations of CRP and insulin resistance index decreased over the period (respectively, p=0.02 and p=0.01), concentrations of IL-6 and TNF-α appeared unchanged (p>0.05). Changes in IL-6 (enhanced) and TNF-α (reduced) concentrations following the prolonged exercise differed compared to days with 40 min exercise and days without exercise (p<0.05). Muscle soreness appeared higher after the 80 min than after the 40-min exercise (p=0.01), and were related with IL-6 and CRP concentration changes. A 5-day period combining exercise and diet reduced the insulin-resistance index and the CRP fasting concentrations. The 80-min exercise enhanced IL-6 and lowered TNF-α concentration changes while days without exercise unaffected these cytokines. These exercise effects on cytokines may have benefited to the insulin resistance index. The duration and number of the exercise sessions appeared sufficient for inactive subjects to initiate health benefits without inducing negative effects on inflammation and muscle soreness.


Assuntos
Dieta , Exercício Físico/psicologia , Inflamação/sangue , Resistência à Insulina , Obesidade/sangue , Adulto , Biomarcadores/sangue , Proteína C-Reativa/química , Exercício Físico/fisiologia , Feminino , Humanos , Interleucina-6/sangue , Pessoa de Meia-Idade , Fator de Necrose Tumoral alfa/sangue
11.
Genes Immun ; 16(8): 514-8, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26378651

RESUMO

Although most hepatitis C virus (HCV)-infected individuals develop chronic infection, about 25% of them are able to clear the virus spontaneously without any therapeutic intervention. The aim of the present study was to identify genes associated with spontaneous HCV clearance in a population of Iranian patients. We genotyped 110 single-nucleotide polymorphisms (SNPs) in 59 selected--candidate--genes in a cohort of 107 HCV-infected participants who spontaneously cleared the infection and 176 participants whose infection persisted. Three out of the 110 SNPs were found to be associated with HCV outcome (P-values<0.03). rs11506105 in EGFR (epidermal growth factor receptor gene), and rs11881222 and rs12979860 in IL28B (interferon-λ3 gene). Multivariate logistic regression of the three markers showed that the A/A genotypes in both rs11506105 (EFGR) and rs11881222 (IL28B), and the C/C genotype in rs12979860 (IL28B) are associated with HCV clearance (recessive model: odds ratio (OR)=2.06, 95% confidence interval (95% CI)=1.09-3.88, P=0.025; OR=2.09, 95% CI=1.23-3.60, P=0.007; and OR=1.95, 95% CI=1.15-3.35, P=0.014 for rs11506105, rs12979860 and rs11881222, respectively). In conclusion, EGFR and IL28B SNPs are strong independent predictive markers of spontaneous viral clearance.


Assuntos
Receptores ErbB/genética , Hepacivirus/fisiologia , Hepatite C/genética , Interleucinas/genética , Polimorfismo de Nucleotídeo Único , Marcadores Genéticos , Hepatite C/imunologia , Humanos , Interferons , Irã (Geográfico) , Análise Multivariada , Remissão Espontânea
12.
Sci Rep ; 5: 12417, 2015 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-26201268

RESUMO

Magnetic domain walls (DWs) in nanostructures are low-dimensional objects that separate regions with uniform magnetisation. Since they can have different shapes and widths, DWs are an exciting playground for fundamental research, and became in the past years the subject of intense works, mainly focused on controlling, manipulating, and moving their internal magnetic configuration. In nanostrips with in-plane magnetisation, two DWs have been identified: in thin and narrow strips, transverse walls are energetically favored, while in thicker and wider strips vortex walls have lower energy. The associated phase diagram is now well established and often used to predict the low-energy magnetic configuration in a given magnetic nanostructure. However, besides the transverse and vortex walls, we find numerically that another type of wall exists in permalloy nanostrips. This third type of DW is characterised by a three-dimensional, flux closure micromagnetic structure with an unusual length and three internal degrees of freedom. Magnetic imaging on lithographically-patterned permalloy nanostrips confirms these predictions and shows that these DWs can be moved with an external magnetic field of about 1 mT. An extended phase diagram describing the regions of stability of all known types of DWs in permalloy nanostrips is provided.

13.
Horm Metab Res ; 47(7): 473-8, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25153683

RESUMO

Perturbations of energy balance induce compensatory processes that may alter expected weight loss. In obese patients, our aim was to investigate the relationships that occurred between fasting plasma concentrations of anorexigenic peptides and metabolic parameters, appetite, physical capacity, and weight loss in the 5 first days of a program associating exercise and caloric reduction. Thirteen obese women were monitored from day 1 to day 5 with 2 exercise sessions in day 2 and day 4. We measured, in a fasted state, changes in body weight, hunger ratings, and plasma concentrations of fatty acids, triglycerides, leptin, insulin, amylin, peptide YY, and insulin-resistance index. Physical performance was assessed by a 6-min walking test. The program resulted in significantly reduced body weight (0.75±0.4 kg; p=0.001), of plasma concentrations of triglycerides, insulin, amylin, peptide YY, and the insulin-resistance index, and also increased fatty acids (p<0.05). Hunger ratings were increased (p<0.05). Program-induced changes in fatty acids, leptin, and insulin concentrations were related to physical performance (r(2)=0.45, 0.59, and 0.52; p<0.05, respectively) and to weight loss (r(2)=0.65, 0.57, 0.55; p<0.05, respectively). Five days of diet and exercise induced weight loss, improved lipid profile, and decreased insulin resistance while hunger ratings increased. Subjects with higher physical capacity lost more weight, presented higher increases in fatty acids and lower changes of leptin and insulin concentrations suggesting a better metabolic flexibility. To reduce the compensatory responses that can occur with energy imbalances, our study supports to account for individual activity level before prescribing weight-loss program associating diet and exercise.


Assuntos
Dieta Redutora , Exercício Físico/fisiologia , Fome/fisiologia , Resistência à Insulina/fisiologia , Obesidade/metabolismo , Obesidade/terapia , Redução de Peso/fisiologia , Adulto , Peso Corporal/fisiologia , Feminino , Humanos , Insulina/sangue , Leptina/sangue , Lipídeos/sangue , Pessoa de Meia-Idade , Obesidade/dietoterapia
14.
J Visc Surg ; 151(1): 9-16, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24388391

RESUMO

BACKGROUND: Despite the prevalence of complex ventral hernias, there is little agreement on the most appropriate technique or prosthetic to repair these defects, especially in contaminated fields. Our objective was to determine French surgical practice patterns among academic surgeons in complex ventral hernia repair (CVHR) with regard to indications, most appropriate techniques, choice of prosthesis, and experience with complications. METHODS: A survey consisting of 21 questions and 6 case-scenarios was e-mailed to French practicing academic surgeons performing CVHR, representing all French University Hospitals. RESULTS: Forty over 54 surgeons (74%) responded to the survey, representing 29 French University Hospitals. Regarding the techniques used for CVHR, primary closure without reinforcement was provided in 31.6% of cases, primary closure using the component separation technique without mesh use in 43.7% of cases, mesh positioned as a bridge in 16.5% of cases, size reduction of the defect by using aponeurotomy incisions without mesh use in 8.2% of cases. Among the 40 respondents, 36 had experience with biologic mesh. There was a strong consensus among surveyed surgeons for not using synthetic mesh in contaminated or dirty fields (100%), but for using it in clean settings (100%). There was also a strong consensus between respondents for using biologic mesh in contaminated (82.5%) or infected (77.5%) fields and for not using it in clean setting (95%). In clean-contaminated surgery, there was no consensus for defining the optimal therapeutic strategy in CVHR. Infection was the most common complication reported after biologic mesh used (58%). The most commonly reported influences for the use of biologic grafts included literature, conferences and discussion with colleagues (85.0%), personal experience (45.0%) and cost (40.0%). CONCLUSIONS: Despite a lack of level I evidence, biologic meshes are being used by 90% of surveyed surgeons for CVHR. Importantly, there was a strong consensus for using them in contaminated or infected fields and for not using them in clean setting. To better guide surgeons, prospective, randomized trials should be undertaken to evaluate the short- and long-term outcomes associated with these materials in various surgical wound classifications.


Assuntos
Atitude do Pessoal de Saúde , Hérnia Ventral/cirurgia , Herniorrafia/métodos , Padrões de Prática Médica/estatística & dados numéricos , Telas Cirúrgicas , Consenso , Feminino , França , Pesquisas sobre Atenção à Saúde , Herniorrafia/instrumentação , Humanos , Masculino
15.
J Phys Condens Matter ; 25(49): 496002, 2013 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-24184960

RESUMO

We develop the self-assembly of epitaxial submicrometer-sized face-centered-cubic (fcc) Co(111) dots using pulsed laser deposition. The dots display atomically flat facets, from which the ratios of surface and interface energies for fcc Co are deduced. Zero-field magnetic structures are investigated with magnetic force and Lorentz microscopies, revealing vortex-based flux-closure patterns. A good agreement is found with micromagnetic simulations.

16.
J Sports Med Phys Fitness ; 53(2): 185-91, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23584326

RESUMO

AIM: The aim of this paper was to investigate the changes over time in anthropometric parameters of young and adult rugby players in France. METHODS: Age, mass and height were collected for 2051 French elite rugby players participating in the championship during the 1988-1989 and the 2008-2009 seasons. The same variables were collected for the best 145 juniors (under 21 years) and 448 U15 (under 15 years) French players for these seasons. Changes in anthropometric parameters were compared according to age, category (back vs. forwards) and season. RESULTS: Over 20 years, adult French rugby backs and forwards have become heavier by 12 kg and 12.3 kg, taller by 5.4 cm and 2.9 cm, respectively. Junior players also became taller and heavier, 6 cm and 9.9 kg for backs and 4.4 cm and 11.1 kg for forwards. U15 backs have gained 5.1 cm and 6.5 kg, and forwards earned 4.7 cm and 4.7 kg. CONCLUSION: Rugby players have become taller and heavier. Their current morphology is the product of a long process of competition and selection. This study demonstrates that this selection of the "large sizes" is already present at a young age.


Assuntos
Antropometria , Desempenho Atlético/fisiologia , Futebol Americano/fisiologia , Adolescente , Adulto , Análise de Variância , França , Humanos , Masculino
17.
J Evol Biol ; 25(9): 1792-9, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22779699

RESUMO

Running speed in animals depends on both genetic and environmental conditions. Maximal speeds were here analysed in horses, dogs and humans using data sets on the 10 best performers covering more than a century of races. This includes a variety of distances in humans (200-1500 m). Speed has been progressing fast in the three species, and this has been followed by a plateau. Based on a Gompertz model, the current best performances reach 97.4% of maximal velocity in greyhounds to 100.3 in humans. Further analysis based on a subset of individuals and using an 'animal model' shows that running speed is heritable in horses (h(2) = 0.438, P = 0.01) and almost so in dogs (h(2) = 0.183, P = 0.08), suggesting the involvement of genetic factors. Speed progression in humans is more likely due to an enlarged population of runners, associated with improved training practices. The analysis of a data subset (40 last years in 800 and 1500 m) further showed that East Africans have strikingly improved their speed, now reaching the upper part of the human distribution, whereas that of Nordic runners stagnated in the 800 m and even declined in the 1500 m. Although speed progression in dogs and horses on one side and humans on the other has not been affected by the same genetic/environmental balance of forces, it is likely that further progress will be extremely limited.


Assuntos
Desempenho Atlético/fisiologia , Cães/fisiologia , Cavalos/fisiologia , Corrida/fisiologia , África Oriental/etnologia , Animais , Fenômenos Biomecânicos , População Negra , Cães/genética , Meio Ambiente , Feminino , Cavalos/genética , Humanos , Masculino , Modelos Biológicos , Característica Quantitativa Herdável , Especificidade da Espécie , Fatores de Tempo
18.
Phys Rev Lett ; 104(12): 127204, 2010 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-20366562

RESUMO

Dimensionality crossover is a classical topic in physics. Surprisingly, it has not been searched in micromagnetism, which deals with objects such as domain walls (2D) and vortices (1D). We predict by simulation a second-order transition between these two objects, with the wall length as the Landau parameter. This was confirmed experimentally based on micron-sized flux-closure dots.

19.
Nanotechnology ; 20(28): 285302, 2009 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-19546492

RESUMO

We report on a new approach, entirely based on an electron-beam lithography technique, to contact electrically, in a four-probe scheme, single nanostructures obtained by self-assembly. In our procedure, nanostructures of interest are located and contacted in the same fabrication step. This technique has been developed to study the field-induced reversal of an internal component of an asymmetric Bloch domain wall observed in elongated structures such as Fe(110) dots. We have focused on the control, using an external magnetic field, of the magnetization orientation within Néel caps that terminate the domain wall at both interfaces. Preliminary magneto-transport measurements are discussed demonstrating that single Fe(110) dots have been contacted.


Assuntos
Elétrons , Compostos Férricos/química , Nanoestruturas/química , Nanotecnologia/métodos , Fotografação/métodos , Microscopia de Força Atômica , Nanoestruturas/ultraestrutura
20.
Phys Rev Lett ; 102(10): 107201, 2009 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-19392153

RESUMO

While magnetic hysteresis usually considers magnetic domains, the switching of the core of magnetic vortices has recently become an active topic. We considered Bloch domain walls, which are known to display at the surface of thin films flux-closure features called Néel caps. We demonstrated the controlled switching of these caps under a magnetic field, occurring via the propagation of a surface vortex. For this we considered flux-closure states in elongated micron-sized dots, so that only the central domain wall can be addressed, while domains remain unaffected.

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