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1.
Proc Natl Acad Sci U S A ; 118(20)2021 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-33980712

RESUMO

We use polarization-resolved electronic Raman spectroscopy to study quadrupolar charge dynamics in a nonmagnetic [Formula: see text] superconductor. We observe two types of long-wavelength [Formula: see text] symmetry excitations: 1) a low-energy quasi-elastic scattering peak (QEP) and 2) a broad electronic continuum with a maximum at 55 meV. Below the tetragonal-to-orthorhombic structural transition at [Formula: see text], a pseudogap suppression with temperature dependence reminiscent of the nematic order parameter develops in the [Formula: see text] symmetry spectra of the electronic excitation continuum. The QEP exhibits critical enhancement upon cooling toward [Formula: see text] The intensity of the QEP grows with increasing sulfur concentration x and maximizes near critical concentration [Formula: see text], while the pseudogap size decreases with the suppression of [Formula: see text] We interpret the development of the pseudogap in the quadrupole scattering channel as a manifestation of transition from the non-Fermi liquid regime, dominated by strong Pomeranchuk-like fluctuations giving rise to intense electronic continuum of excitations in the fourfold symmetric high-temperature phase, to the Fermi liquid regime in the broken-symmetry nematic phase where the quadrupole fluctuations are suppressed.

2.
J Appl Biomech ; 39(2): 90-98, 2023 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-36848903

RESUMO

This study aims to investigate the difference in hand acceleration induced by rapid changes in hand movement directions and propulsion between fast and slow groups of swimmers during front crawl swimming. Twenty-two participants, consisting of 11 fast and 11 slow swimmers, performed front crawl swimming at their maximal effort. Hand acceleration and velocity and the angle of attack were measured using a motion capture system. The dynamic pressure approach was used to estimate hand propulsion. In the insweep phase, the fast group attained significantly higher hand acceleration than the slow group in the lateral and vertical directions (15.31 [3.44] m·s-2 vs 12.23 [2.60] m·s-2 and 14.37 [1.70] m·s-2 vs 12.15 [1.21] m·s-2), and the fast group exerted significantly larger hand propulsion than the slow group (53 [5] N vs 44 [7] N). Although the fast group attained large hand acceleration and propulsion during the insweep phase, the hand velocity and the angle of attack were not significantly different in the 2 groups. The rapid change in hand movement direction could be considered in the technique of underwater arm stroke, particularly in the vertical direction, to increase hand propulsion during front crawl swimming.


Assuntos
Mãos , Natação , Humanos , Fenômenos Biomecânicos , Extremidade Superior , Movimento
3.
Eur Heart J ; 42(4): 308-319, 2021 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-33284979

RESUMO

AIMS: After percutaneous coronary intervention (PCI) with second-generation drug-eluting stent (DES), whether short dual antiplatelet therapy (DAPT) followed by single antiplatelet therapy (SAPT) with a P2Y12 receptor inhibitor confers benefits compared with prolonged DAPT is unclear. METHODS AND RESULTS: Multiple electronic databases, including PubMed, Scopus, Web of Sciences, Ovid, and ScienceDirect, were searched to identify randomized clinical trials comparing ≤3 months of DAPT followed by P2Y12 inhibitor SAPT vs. 12 months of DAPT after PCI with second-generation DES implantation. The primary and co-primary outcomes of interest were major bleeding and stent thrombosis 1 year after randomization. Summary hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated by fixed-effect and random-effects models. Multiple sensitivity analyses including random-effects models 95% CI adjustment were applied. A sensitivity analysis comparing trials using P2Y12 inhibitor SAPT with those using aspirin SAPT was performed. A total of five randomized clinical trials (32 145 patients) were available. Major bleeding was significantly lower in the patients assigned to short DAPT followed by P2Y12 inhibitor SAPT compared with those assigned to 12-month DAPT (random-effects model: HR 0.63, 95% 0.45-0.86). No significant differences between groups were observed in terms of stent thrombosis (random-effects model: HR 1.19, 95% CI 0.86-1.65) and the secondary endpoints of all-cause death (random-effects model: HR 0.85, 95% CI 0.70-1.03), myocardial infarction (random-effects model: HR 1.05, 95% CI 0.89-1.23), and stroke (random-effects model: HR 1.08, 95% CI 0.68-1.74). Sensitivity analyses showed overall consistent results. By comparing trials testing ≤3 months of DAPT followed by P2Y12 inhibitor SAPT vs. 12 months of DAPT with trials testing ≤3 months of DAPT followed by aspirin SAPT vs. 12-month of DAPT, there was no treatment-by-subgroup interaction for each endpoint. By combining all these trials, regardless of the type of SAPT, short DAPT was associated with lower major bleeding (random-effects model: HR 0.63, 95% CI 0.48-0.83) and no differences in stent thrombosis, all-cause death, myocardial infarction, and stroke were observed between regimens. CONCLUSION: After second-generation DES implantation, 1-3 months of DAPT followed by P2Y12 inhibitor SAPT is associated with lower major bleeding and similar stent thrombosis, all-cause death, myocardial infarction, and stroke compared with prolonged DAPT. Whether P2Y12 inhibitor SAPT is preferable to aspirin SAPT needs further investigation.


Assuntos
Stents Farmacológicos , Intervenção Coronária Percutânea , Quimioterapia Combinada , Humanos , Inibidores da Agregação Plaquetária/uso terapêutico , Antagonistas do Receptor Purinérgico P2Y , Ensaios Clínicos Controlados Aleatórios como Assunto , Resultado do Tratamento
4.
Catheter Cardiovasc Interv ; 97(4): E536-E543, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-32584507

RESUMO

BACKGROUND: Stroke is a feared complication of transcatheter aortic valve replacement (TAVR) and surgical aortic valve replacement (SAVR). OBJECTIVES: With this meta-analysis we aimed to evaluate the incidence of 30-day stroke with TAVR and SAVR focusing on its possible correlation with surgical risk. METHODS: Major electronic databases were searched for studies published between January 2002 and October 2019 reporting the rates of 30-day stroke after TAVR and SAVR. Data were pooled using fixed- and random-effects models. The primary outcome of the study was stroke rate within 30-day from TAVR or SAVR. Results were stratified according to surgical risk score (high, intermediate and low). RESULTS: A total of 23 studies were identified (TAVR: 14,589 patients; SAVR: 11,681 patients). Regardless of the model used, in the overall population TAVR was associated with a significant reduction in the risk of stroke compared with SAVR (fixed effect: OR 0.78, 95% CI 0.66-0.92, p = .003; random-effects: OR 0.80, 95% CI 0.64-1.00, p = .045). Rates of 30-day stroke after TAVR and SAVR were not significantly different in the high- (OR 1.01, 95% CI 0.44-1.98, p = .105) and intermediate-risk groups (OR 0.92, 95% CI 0.63-1.36, p = .319), while low-risk patients had a lower rate of 30-day stroke after TAVR than SAVR (OR 0.65, 95% CI 0.50-0.83, p < .001). Meta-regression showed a significant association between surgical risk score and 30-day stroke rate (p = .007). CONCLUSIONS: TAVR is associated with a lower risk of 30-day stroke compared with SAVR, mainly as a result of the significant advantage observed in patients at low surgical risk.


Assuntos
Estenose da Valva Aórtica , Implante de Prótese de Valva Cardíaca , Acidente Vascular Cerebral , Substituição da Valva Aórtica Transcateter , Valva Aórtica/diagnóstico por imagem , Valva Aórtica/cirurgia , Estenose da Valva Aórtica/diagnóstico por imagem , Estenose da Valva Aórtica/cirurgia , Implante de Prótese de Valva Cardíaca/efeitos adversos , Humanos , Fatores de Risco , Acidente Vascular Cerebral/epidemiologia , Acidente Vascular Cerebral/etiologia , Substituição da Valva Aórtica Transcateter/efeitos adversos , Resultado do Tratamento
5.
Proc Natl Acad Sci U S A ; 115(6): 1227-1231, 2018 02 06.
Artigo em Inglês | MEDLINE | ID: mdl-29363600

RESUMO

The emergence of the nematic electronic state that breaks rotational symmetry is one of the most fascinating properties of the iron-based superconductors, and has relevance to cuprates as well. FeSe has a unique ground state in which superconductivity coexists with a nematic order without long-range magnetic ordering, providing a significant opportunity to investigate the role of nematicity in the superconducting pairing interaction. Here, to reveal how the superconducting gap evolves with nematicity, we measure the thermal conductivity and specific heat of FeSe1 - x S x , in which the nematicity is suppressed by isoelectronic sulfur substitution and a nematic critical point (NCP) appears at [Formula: see text] We find that, in the whole nematic regime ([Formula: see text]), the field dependence of two quantities consistently shows two-gap behavior; one gap is small but highly anisotropic with deep minima or line nodes, and the other is larger and more isotropic. In stark contrast, in the tetragonal regime ([Formula: see text]), the larger gap becomes strongly anisotropic, demonstrating an abrupt change in the superconducting gap structure at the NCP. Near the NCP, charge fluctuations of [Formula: see text] and [Formula: see text] orbitals are enhanced equally in the tetragonal side, whereas they develop differently in the orthorhombic side. Our observation therefore directly implies that the orbital-dependent nature of the nematic fluctuations has a strong impact on the superconducting gap structure and hence on the pairing interaction.

6.
Curr Cardiol Rep ; 23(3): 15, 2021 01 25.
Artigo em Inglês | MEDLINE | ID: mdl-33495895

RESUMO

PURPOSE OF REVIEW: In this review, we discuss about the reasons behind the failure of the Absorb bioresorbable vascular scaffold (BVS) device and about the challenges the future holds for the next generation of the bioresorbable scaffold (BRS) technology. RECENT FINDINGS: Absorb BVS was burdened by intrinsic structural limitations which resulted in augmented rates of device thrombosis and clinical adverse events compared to current-generation metallic stent. Nevertheless, new generation devices with novel design and materials are in development. Second generation BRS have enhanced mechanical strength, smaller footprints, less thrombogenicity and modified bioresorption. These features, paired with proper patient and lesion selection and optimal "user-friendly" implant techniques, could possibly overcome the previous BRS generation limitations, rekindling physicians, and industry interest on this promising technology.


Assuntos
Doença da Artéria Coronariana , Stents Farmacológicos , Intervenção Coronária Percutânea , Implantes Absorvíveis , Doença da Artéria Coronariana/cirurgia , Humanos , Desenho de Prótese , Fatores de Tempo , Resultado do Tratamento
7.
Catheter Cardiovasc Interv ; 96(5): E535-E541, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-31912968

RESUMO

BACKGROUND: Incidence of coronary access (CA) after transcatheter aortic valve replacement (TAVR) at long-term follow-up remains unknown. CA and percutaneous coronary intervention (PCI) after TAVR might present technical challenges, particularly with supra-annular devices. METHODS: Patients undergoing CA after being treated with TAVR at our institution were included in the study. Coronary interventions for coronary obstruction during TAVR procedure were excluded. Incidence, feasibility and outcomes of CA after TAVR were analyzed. RESULTS: Out of 912 patients aged 80 ± 7 years treated with TAVR at our institution between 2007 and 2018, 48 (5.3%) underwent CA at a median follow up of 769 [363-1,471] days. Twenty-one had received a SAPIEN XT, 15 a SAPIEN 3, 6 Corevalve, 2 Evolut Pro, 2 JenaValve, and 2 Lotus valve. PCI was indicated in 26 (54%) cases. Seventeen (35%) procedures were performed for acute coronary syndromes (ACS). Independent predictors of CA after TAVR were younger age, previous PCI, and CABG. CA of both vessels was feasible in all patients with an intra-annular device, while the right coronary artery was not engaged in two patients with a supra-annular valve. PCI was successful in all but one case. All-cause mortality was similar between patients needing CA for ACS and those who had other clinical indications. CONCLUSIONS: In this high-risk AS population, incidence of CA after TAVR at long-term follow-up was rather low. CA and PCI were safe and successful in most cases, with a lower rate of selective CA for supra-annular devices.


Assuntos
Estenose da Valva Aórtica/cirurgia , Cateterismo Cardíaco , Angiografia Coronária , Estenose Coronária/diagnóstico , Estenose Coronária/terapia , Intervenção Coronária Percutânea , Substituição da Valva Aórtica Transcateter , Idoso , Idoso de 80 Anos ou mais , Estenose da Valva Aórtica/diagnóstico por imagem , Estenose da Valva Aórtica/mortalidade , Cateterismo Cardíaco/efeitos adversos , Cateterismo Cardíaco/mortalidade , Angiografia Coronária/efeitos adversos , Angiografia Coronária/mortalidade , Estenose Coronária/mortalidade , Estudos de Viabilidade , Feminino , Próteses Valvulares Cardíacas , Humanos , Masculino , Intervenção Coronária Percutânea/efeitos adversos , Intervenção Coronária Percutânea/mortalidade , Desenho de Prótese , Estudos Retrospectivos , Medição de Risco , Fatores de Risco , Fatores de Tempo , Substituição da Valva Aórtica Transcateter/efeitos adversos , Substituição da Valva Aórtica Transcateter/instrumentação , Substituição da Valva Aórtica Transcateter/mortalidade , Resultado do Tratamento
8.
Int Heart J ; 61(4): 665-672, 2020 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-32684594

RESUMO

Clinical outcomes after percutaneous coronary intervention (PCI) for severely calcified lesions remain poor. The purpose of this study was to investigate the neointimal response after everolimus-eluting stents (EES) for severely calcified lesions treated with rotational atherectomy (RA) using optical coherence tomography (OCT).We retrospectively analyzed 34 lesions in which PCI was performed with EES deployment following RA and OCT was performed immediately after PCI and at follow-up (nine months). The EES was either durable-polymer (DP) EES (22 lesions) or bioabsorbable polymer (BP) -EES (12 lesions). Strut coverage and malapposition were evaluated at 1-mm intervals of cross-section (CS) by serial OCT analysis. Malapposed strut was defined as having the distance from luminal border > 100 µm.A total of 11,823 struts immediately after PCI and 11,720 struts at follow-up were analyzed. Immediately after PCI, the strut-level analysis showed no significant differences in the percentage of malapposed struts between the DP-EES group and the BP-EES group. At follow-up, the BP-EES group showed a more prevalent covered strut compared with the DP-EES group (strut-level analysis: 95% versus 97%, P = 0.045; CS-level analysis: 97% versus 100%, P < 0.01; lesion-level analysis: 27% versus 83%, P < 0.01, respectively).In severely calcified lesions requiring RA, the BP-EES group achieved better neointimal coverage than the DP-EES group at nine months. Additional prospective studies are needed.


Assuntos
Implantes Absorvíveis/estatística & dados numéricos , Aterectomia Coronária/instrumentação , Stents Farmacológicos/estatística & dados numéricos , Neointima/prevenção & controle , Idoso , Idoso de 80 Anos ou mais , Antineoplásicos/administração & dosagem , Everolimo/administração & dosagem , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Polímeros , Estudos Retrospectivos , Tomografia de Coerência Óptica
9.
J Interv Cardiol ; 2019: 9282876, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31772552

RESUMO

BACKGROUND: While the evaluation of burr speed was discussed regarding platelet aggregation, the association between platform speed and acute lumen gain of rotational atherectomy remains unknown. METHODS: Through the evaluation of the potential of low-speed rotational atherectomy (LSRA) in in-vitro experiments, minimum lumen diameter (MLD) and minimum lumen area (MLA) after conventional high-speed rotational atherectomy (HSRA group) and those after LSRA following HSRA (LSRA+HSRA group) treated by 1.5 mm burrs were measured by optical frequency domain imaging (OFDI) in 30 consecutive human lesions. RESULTS: The in-vitro experiments demonstrated that MLD and MLA after LSRA+HSRA were significantly larger (MLD: LSRA+HSRA=1.50 ±0.05 mm, HSRA= 1.43 ±0.05 mm, p=0.015; MLA: LSRA+HSRA= 1.90 ±0.17 mm2, HSRA= 1.71±0.11 mm2, and p= 0.037), requiring more crossing attempts (LSRA= 134 ±20 times, HSRA= 72 ±11 times, and p< 0.001). In human studies, there was no significance in reference vessel diameter and lesion length before the procedure between two groups. MLDs after LSRA+HSRA were significantly larger than those in HSRA (LSRA+HSRA= 1.22 ±0.16 mm, HSRA= 1.07 ±0.14 mm, and p= 0.0078), while MLAs after LSRA+HSRA tended to be larger (LSRA+HSRA= 1.79 ±0.51 mm2, HSRA= 1.55 ±0.47 mm2, and p= 0.19). There was no significance in the occurrence of in-hospital complication, including slow flow or no reflow, major dissection, and procedural myocardial infarction, between LSRA+HSRA and HSRA. CONCLUSIONS: LSRA can achieve larger lumen gain compared, whereas HSRA can pass calcified lesions easily. Combination of LSRA and HSRA is a safe and feasible strategy for severely calcified lesions in clinical practice.


Assuntos
Aterectomia Coronária , Doença da Artéria Coronariana , Vasos Coronários , Teste de Materiais/métodos , Intervenção Coronária Percutânea/métodos , Idoso , Aterectomia Coronária/efeitos adversos , Aterectomia Coronária/instrumentação , Aterectomia Coronária/métodos , Doença da Artéria Coronariana/patologia , Doença da Artéria Coronariana/cirurgia , Vasos Coronários/diagnóstico por imagem , Vasos Coronários/patologia , Vasos Coronários/cirurgia , Desenho de Equipamento , Feminino , Humanos , Japão , Masculino , Pessoa de Meia-Idade , Cirurgia Assistida por Computador/métodos , Resultado do Tratamento , Calcificação Vascular/cirurgia
10.
Proc Natl Acad Sci U S A ; 113(31): 8653-7, 2016 08 02.
Artigo em Inglês | MEDLINE | ID: mdl-27439874

RESUMO

When quantum fluctuations destroy underlying long-range ordered states, novel quantum states emerge. Spin-liquid (SL) states of frustrated quantum antiferromagnets, in which highly correlated spins fluctuate down to very low temperatures, are prominent examples of such quantum states. SL states often exhibit exotic physical properties, but the precise nature of the elementary excitations behind such phenomena remains entirely elusive. Here, we use thermal Hall measurements that can capture the unexplored property of the elementary excitations in SL states, and report the observation of anomalous excitations that may unveil the unique features of the SL state. Our principal finding is a negative thermal Hall conductivity [Formula: see text] which the charge-neutral spin excitations in a gapless SL state of the 2D kagomé insulator volborthite Cu3V2O7(OH)2[Formula: see text]2H2O exhibit, in much the same way in which charged electrons show the conventional electric Hall effect. We find that [Formula: see text] is absent in the high-temperature paramagnetic state and develops upon entering the SL state in accordance with the growth of the short-range spin correlations, demonstrating that [Formula: see text] is a key signature of the elementary excitation formed in the SL state. These results suggest the emergence of nontrivial elementary excitations in the gapless SL state which feel the presence of fictitious magnetic flux, whose effective Lorentz force is found to be less than 1/100 of the force experienced by free electrons.

11.
Proc Natl Acad Sci U S A ; 113(29): 8139-43, 2016 07 19.
Artigo em Inglês | MEDLINE | ID: mdl-27382157

RESUMO

In most unconventional superconductors, the importance of antiferromagnetic fluctuations is widely acknowledged. In addition, cuprate and iron-pnictide high-temperature superconductors often exhibit unidirectional (nematic) electronic correlations, including stripe and orbital orders, whose fluctuations may also play a key role for electron pairing. In these materials, however, such nematic correlations are intertwined with antiferromagnetic or charge orders, preventing the identification of the essential role of nematic fluctuations. This calls for new materials having only nematicity without competing or coexisting orders. Here we report systematic elastoresistance measurements in FeSe1-xSx superconductors, which, unlike other iron-based families, exhibit an electronic nematic order without accompanying antiferromagnetic order. We find that the nematic transition temperature decreases with sulfur content x; whereas, the nematic fluctuations are strongly enhanced. Near [Formula: see text], the nematic susceptibility diverges toward absolute zero, revealing a nematic quantum critical point. The obtained phase diagram for the nematic and superconducting states highlights FeSe1-xSx as a unique nonmagnetic system suitable for studying the impact of nematicity on superconductivity.

12.
Proc Natl Acad Sci U S A ; 113(33): 9177-81, 2016 08 16.
Artigo em Inglês | MEDLINE | ID: mdl-27482118

RESUMO

The spontaneous appearance of nematicity, a state of matter that breaks rotation but not translation symmetry, is one of the most intriguing properties of the iron-based superconductors (Fe SC), and has relevance for the cuprates as well. Establishing the critical electronic modes behind nematicity remains a challenge, however, because their associated susceptibilities are not easily accessible by conventional probes. Here, using FeSe as a model system, and symmetry-resolved electronic Raman scattering as a probe, we unravel the presence of critical charge nematic fluctuations near the structural/nematic transition temperature, [Formula: see text] 90 K. The diverging behavior of the associated nematic susceptibility foretells the presence of a Pomeranchuk instability of the Fermi surface with d-wave symmetry. The excellent scaling between the observed nematic susceptibility and elastic modulus data demonstrates that the structural distortion is driven by this d-wave Pomeranchuk transition. Our results make a strong case for charge-induced nematicity in FeSe.

13.
J Interv Cardiol ; 31(5): 624-631, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29989210

RESUMO

OBJECTIVES: To evaluate the effectiveness of the proximal optimization technique (POT) to prevent longitudinal stent elongation. BACKGROUND: The mechanism of stent elongation, which occurs after post-balloon dilation, is still unclear. METHODS: A total of 103 lesions treated with optical coherence tomography guided coronary intervention between May 2013 and November 2017 were retrospectively analyzed. Lesions were divided according to the circumferential degree of malapposition at the stent edge immediately after deployment into well-apposed group (<180°) and malapposed group (≥180°). Post-dilation was performed from distal to proximal within the stent until August 2016 (non-POT cohort), and POT was applied thereafter (POT cohort). In the POT cohort, post-dilation was done at the proximal portion of the stent with sufficiently large balloon to minimize malapposition followed by distal dilatations. Stent elongation length was defined as the change in stent length from stent deployment to after post-dilatation. RESULTS: In the non-POT cohort, 72 lesions, including 54 lesions in the well-apposed group and 18 in the malapposed group were analyzed. Stent elongation length was significantly longer in the malapposed group than in the well-apposed group (1.51 ± 1.34 mm vs 0.13 ± 0.84 mm, P < 0.01). In the POT cohort, 31 lesions including 21 in the well-apposed group and 10 in the malapposed group were analyzed. Stent elongation length was not significantly different between the groups (-0.09 ± 0.91 mm vs 0.30 ± 0.99 mm, P = 0.29). CONCLUSIONS: Malapposition of the stent edge is responsible for longitudinal stent elongation caused by post-dilatation. POT appeared to effectively prevent longitudinal stent elongation.


Assuntos
Angioplastia Coronária com Balão , Vasos Coronários , Stents/efeitos adversos , Idoso , Angioplastia Coronária com Balão/efeitos adversos , Angioplastia Coronária com Balão/instrumentação , Angioplastia Coronária com Balão/métodos , Vasos Coronários/diagnóstico por imagem , Vasos Coronários/cirurgia , Feminino , Humanos , Japão , Masculino , Pessoa de Meia-Idade , Complicações Pós-Operatórias/etiologia , Complicações Pós-Operatórias/prevenção & controle , Falha de Prótese , Estudos Retrospectivos , Cirurgia Assistida por Computador/métodos , Tomografia de Coerência Óptica/métodos
14.
J Appl Biomech ; 34(4): 342-347, 2018 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-29613822

RESUMO

Center of mass (CoM) velocity variation in swimming direction is related to swimming performance and efficiency. However, it is difficult to calculate the CoM velocity during swimming. Therefore, we aimed to establish a practical estimation method for the CoM velocity in swimming direction during front crawl swimming with underwater cameras. Ten swimmers were recorded during front crawl swimming (25 m, maximal effort) using a motion capture system with 18 underwater and 9 land cameras. Three CoM velocity estimation methods were constructed (single-hip velocity, both-hips velocity, and both-hips velocity with simulated arm velocity correction). Each model was validated against the actual CoM velocity. The difference between the single-hip velocity and the actual CoM velocity in swimming direction was significantly larger compared with that of the other 2 models. Furthermore, the accuracy of CoM velocity estimation was increased when both-hips velocity was corrected using the simulated arm velocity. The method allowed estimation of the CoM velocity with only 2 underwater cameras with a maximal difference of 0.06 m·s-1. This study established a novel and practical method for the estimation of the CoM velocity in swimming direction during front crawl swimming.


Assuntos
Braço/fisiologia , Quadril/fisiologia , Natação/fisiologia , Adolescente , Desempenho Atlético , Fenômenos Biomecânicos , Humanos , Adulto Jovem
15.
Proc Natl Acad Sci U S A ; 111(46): 16309-13, 2014 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-25378706

RESUMO

Fermi systems in the cross-over regime between weakly coupled Bardeen-Cooper-Schrieffer (BCS) and strongly coupled Bose-Einstein-condensate (BEC) limits are among the most fascinating objects to study the behavior of an assembly of strongly interacting particles. The physics of this cross-over has been of considerable interest both in the fields of condensed matter and ultracold atoms. One of the most challenging issues in this regime is the effect of large spin imbalance on a Fermi system under magnetic fields. Although several exotic physical properties have been predicted theoretically, the experimental realization of such an unusual superconducting state has not been achieved so far. Here we show that pure single crystals of superconducting FeSe offer the possibility to enter the previously unexplored realm where the three energies, Fermi energy εF, superconducting gap Δ, and Zeeman energy, become comparable. Through the superfluid response, transport, thermoelectric response, and spectroscopic-imaging scanning tunneling microscopy, we demonstrate that εF of FeSe is extremely small, with the ratio Δ/εF ~ 1(~0.3) in the electron (hole) band. Moreover, thermal-conductivity measurements give evidence of a distinct phase line below the upper critical field, where the Zeeman energy becomes comparable to εF and Δ. The observation of this field-induced phase provides insights into previously poorly understood aspects of the highly spin-polarized Fermi liquid in the BCS-BEC cross-over regime.

16.
J Sports Sci ; 35(10): 945-952, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-27414043

RESUMO

This study re-evaluated the magnitude of hand propulsion (HP) in the pull and push phases of the front crawl stroke and investigated the association between the angular velocity of shoulder roll (ωSR) and hand propulsive lift (HPL). ωSR was computed in the plane normal to a forward direction for 16 skilled swimmers performing the front crawl stroke at a maximal sprinting pace. HP, hand propulsive drag (HPD) and HPL were determined by a dynamic pressure approach. HP and HPD in the pull phase were greater than in the push phase (P < 0.05) while HPL in the pull phase was similar to that in the push phase. Eleven swimmers out of the 16 swimmers had a significant within-swimmers correlation between ωSR and HPL in the push phase (P < 0.05). That is, HPL increased in the push phase as the ωSR of rolling back to the neutral position became faster. A swimmer should use more drag for hand propulsion in the pull phase and propulsion from drag and lift equally in the push phase. Based on the relationship between ωSR and HPL in the push phase, a possible stroke technique to enhance HPL using ωSR is discussed.


Assuntos
Mãos/fisiologia , Movimento/fisiologia , Ombro/fisiologia , Natação/fisiologia , Fenômenos Biomecânicos , Humanos , Masculino , Pressão , Estudos de Tempo e Movimento , Adulto Jovem
17.
Biochemistry ; 55(23): 3198-203, 2016 06 14.
Artigo em Inglês | MEDLINE | ID: mdl-27185533

RESUMO

Membrane-intrinsic nitric oxide reductases (NORs) are key components of bacterial denitrification pathways with a close evolutionary relationship to the cytochrome oxidase (COX) complex found in aerobic respiratory chains. A key distinction between COX and NOR is the identity of the metal directly opposite heme b3 within the active site. In NOR, this metal is iron (FeB), whereas in COX, it is copper (CuB). The purified NOR of Roseobacter denitrificans contains copper and has modest oxidase activity, raising the possibility that a COX-like active site might have independently arisen within the context of a NOR-like protein scaffold. Here we present the crystal structure of the Roseobacter denitrificans NorBC complex and anomalous scattering experiments probing the identity of each metal center. Our results refute the hypothesis that copper occupies the active site and instead reveal a new metal center in the small subunit not seen in any other NOR or COX.


Assuntos
Membrana Celular/metabolismo , Cobre/metabolismo , Heme/metabolismo , Ferro/metabolismo , Oxirredutases/química , Oxirredutases/metabolismo , Roseobacter/enzimologia , Domínio Catalítico , Cristalização , Cristalografia por Raios X , Complexo IV da Cadeia de Transporte de Elétrons/química , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Conformação Proteica
18.
Rep Prog Phys ; 79(7): 074503, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-27275757

RESUMO

The realization of new classes of ground states in strongly correlated electron systems continues to be a major issue in condensed matter physics. Heavy fermion materials, whose electronic structure is essentially three-dimensional, are one of the most suitable systems for obtaining novel electronic states because of their intriguing properties associated with many-body effects. Recently, a state-of-the-art molecular beam epitaxy technique was developed to reduce the dimensionality of heavy electron systems by fabricating artificial superlattices that include heavy fermion compounds; this approach can produce a new type of electronic state in two-dimensional (2D) heavy fermion systems. In artificial superlattices of the antiferromagnetic heavy fermion compound CeIn3 and the conventional metal LaIn3, the magnetic order is suppressed by a reduction in the thickness of the CeIn3 layers. In addition, the 2D confinement of heavy fermions leads to enhancement of the effective electron mass and deviation from the standard Fermi liquid electronic properties, which are both associated with the dimensional tuning of quantum criticality. In the superconducting superlattices of the heavy fermion superconductor CeCoIn5 and nonmagnetic metal YbCoIn5, signatures of superconductivity are observed even at the thickness of one unit-cell layer of CeCoIn5. The most remarkable feature of this 2D heavy fermion superconductor is that the thickness reduction of the CeCoIn5 layers changes the temperature and angular dependencies of the upper critical field significantly. This result is attributed to a substantial suppression of the Pauli pair-breaking effect through the local inversion symmetry breaking at the interfaces of CeCoIn5 block layers. The importance of the inversion symmetry breaking in this system has also been supported by site-selective nuclear magnetic resonance spectroscopy, which can resolve spectroscopic information from each layer separately, even within the same CeCoIn5 block layer. In addition, recent experiments involving CeCoIn5/YbCoIn5 superlattices have shown that the degree of the inversion symmetry breaking and, in turn, the Rashba splitting are controllable, offering the prospect of achieving even more fascinating superconducting states. Thus, these Kondo superlattices pave the way for the exploration of unconventional metallic and superconducting states.

19.
Heart Vessels ; 31(12): 1943-1949, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26968994

RESUMO

The acetylcholine (ACh) provocation test (ACh-test) is used for the diagnosis of vasospastic angina (VSA). However, subjects often show a moderate spasm (MS) response for which diagnosis of VSA is not definitive, and the clinical significance of this response is unknown. We assessed moderate coronary vasomotor response to the ACh test as an indicator of long-term prognosis. A total of 298 consecutive patients who underwent the ACh test for suspected VSA were retrospectively investigated. Coronary spasm severity after intracoronary administration of isosorbide dinitrate was evaluated by measuring epicardial coronary artery diameter reduction after ACh injection. Patients were divided into three groups according to the diameter reduction during the ACh test: severe spasm (SS) showing ≥75 % diameter reduction, MS showing ≥50 % diameter reduction, and others (N). In Kaplan-Meier analysis, the major adverse cardiac event (MACE) rates with a median follow-up of 4.6 years were significantly worse in SS (11.1 %) and MS (8.5 %) than N (1.9 %), (SS vs N; P = 0.009, MS vs N; P = 0.029). Significant difference in MACE rates was not observed between SS and MS (P = 0.534). Cox regression analysis revealed that MS remained an independent predictor of MACE after adjustment for other confounders (HR: 7.18, 95 % CI 1.42-36.4, P = 0.017). Patients with MS by ACh test had a cardiac event rate comparable with that of patients with SS and significantly worse than that of patients with normal vasomotor responses.


Assuntos
Acetilcolina/administração & dosagem , Angina Pectoris/diagnóstico , Vasos Coronários/efeitos dos fármacos , Testes de Função Cardíaca , Vasoconstrição/efeitos dos fármacos , Vasoconstritores/administração & dosagem , Sistema Vasomotor/efeitos dos fármacos , Idoso , Angina Pectoris/fisiopatologia , Distribuição de Qui-Quadrado , Angiografia Coronária , Vasoespasmo Coronário/diagnóstico , Vasoespasmo Coronário/fisiopatologia , Vasos Coronários/fisiopatologia , Feminino , Humanos , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Valor Preditivo dos Testes , Prognóstico , Modelos de Riscos Proporcionais , Estudos Retrospectivos , Índice de Gravidade de Doença , Fatores de Tempo , Sistema Vasomotor/fisiopatologia
20.
Proc Natl Acad Sci U S A ; 110(9): 3293-7, 2013 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-23404698

RESUMO

When a second-order magnetic phase transition is tuned to zero temperature by a nonthermal parameter, quantum fluctuations are critically enhanced, often leading to the emergence of unconventional superconductivity. In these "quantum critical" superconductors it has been widely reported that the normal-state properties above the superconducting transition temperature T(c) often exhibit anomalous non-Fermi liquid behaviors and enhanced electron correlations. However, the effect of these strong critical fluctuations on the superconducting condensate below T(c) is less well established. Here we report measurements of the magnetic penetration depth in heavy-fermion, iron-pnictide, and organic superconductors located close to antiferromagnetic quantum critical points, showing that the superfluid density in these nodal superconductors universally exhibits, unlike the expected T-linear dependence, an anomalous 3/2 power-law temperature dependence over a wide temperature range. We propose that this noninteger power law can be explained if a strong renormalization of effective Fermi velocity due to quantum fluctuations occurs only for momenta k close to the nodes in the superconducting energy gap Δ(k). We suggest that such "nodal criticality" may have an impact on low-energy properties of quantum critical superconductors.

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