42 research outputs found

    All-mode Renormalization for Tensor Network with Stochastic Noise

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    In usual (non-stochastic) tensor network calculations, the truncated singular value decomposition (SVD) is often used for approximating a tensor, and it causes systematic errors. By introducing stochastic noise in the approximation, however, one can avoid such systematic errors at the expense of statistical errors which can be straightforwardly controlled. Therefore in principle, exact results can be obtained even at finite bond dimension up to the statistical errors. A previous study of the unbiased method implemented in tensor renormalization group (TRG) algorithm, however, showed that the statistical errors for physical quantity are not negligible, and furthermore the computational cost is linearly proportional to a system volume. In this paper, we introduce a new way of stochastic noise such that the statistical error is suppressed, and moreover, in order to reduce the computational cost we propose common noise method whose cost is proportional to the logarithm of volume. We find that the method provides better accuracy for the free energy compared with the truncated SVD when applying to TRG for Ising model on square lattice. Although the common noise method introduces systematic error originated from a correlation of noises, we show that the error can be described by a simple functional form in terms of the number of noises, thus the error can be straightforwardly controlled in an actual analysis. We also apply the method to the graph independent local truncation algorithm and show that the accuracy is further improved.Comment: 34 pages, 19 figures, 2 tables, version published in Phys.Rev.

    Principles of the magnetic resonance imaging movie method for articulatory movement : a review

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    Magnetic resonance imaging (MRI) has become a critical tool for dental examination. MRI has many advantages over radiographic examination methods, including the lack of a requirement for patient exposure and the ability to capture high-contrast images of various tissue and organ types. However, MRI also has several limitations, including long examination times and the existence of metallic or motion artifacts. A cardiac imaging method using cine sequences was developed in the 1990s. This technique allows for analysis of heart movement and functional blood flow. Moreover, this method has been applied in dentistry. Recent research involving 3T MRI has led to the achievement of a temporal resolution of <10 ms, surpassing the frame rate of typical video recording. The current review introduces the history and principles of the cine sequence method and its application to the oral and maxillofacial regions

    Alstiphyllanines I–O, ajmaline type alkaloids from Alstonia macrophylla showing vasorelaxant activity

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    Seven new ajmaline type alkaloids, alstiphyllanines I–O (1–7) were isolated from the leaves of Alstonia macrophylla together with six related alkaloids (8–13). Structures and stereochemistry of 1–7 were fully elucidated and characterized by 2D NMR analysis. A series of alstiphyllanines I–O (1–7) as well as the known ajmaline type alkaloids (8–13) showed that they relaxed phenylephrine (PE)-induced contractions against rat aortic ring. Among them, vincamedine (10) showed potent vasorelaxant activity, which may be mediated through inhibition of Ca2+ influx through voltage-dependent Ca2+ channels (VDCs) and/or receptor-operated Ca2+ channels (ROCs) as well as partially mediated the NO release from endothelial cells. The presence of substituents at both N-1 and C-17 may be important to show vasorelaxation activity

    Abundant Occurrence of Basal Radial Glia in the Subventricular Zone of Embryonic Neocortex of a Lissencephalic Primate, the Common Marmoset Callithrix jacchus

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    Subventricular zone (SVZ) progenitors are a hallmark of the developing neocortex. Recent studies described a novel type of SVZ progenitor that retains a basal process at mitosis, sustains expression of radial glial markers, and is capable of self-renewal. These progenitors, referred to here as basal radial glia (bRG), occur at high relative abundance in the SVZ of gyrencephalic primates (human) and nonprimates (ferret) but not lissencephalic rodents (mouse). Here, we analyzed the occurrence of bRG cells in the embryonic neocortex of the common marmoset Callithrix jacchus, a near-lissencephalic primate. bRG cells, expressing Pax6, Sox2 (but not Tbr2), glutamate aspartate transporter, and glial fibrillary acidic protein and retaining a basal process at mitosis, occur at similar relative abundance in the marmoset SVZ as in human and ferret. The proportion of progenitors in M-phase was lower in embryonic marmoset than developing ferret neocortex, raising the possibility of a longer cell cycle. Fitting the gyrification indices of 26 anthropoid species to an evolutionary model suggested that the marmoset evolved from a gyrencephalic ancestor. Our results suggest that a high relative abundance of bRG cells may be necessary, but is not sufficient, for gyrencephaly and that the marmoset's lissencephaly evolved secondarily by changing progenitor parameters other than progenitor type

    Comparison of blood pressure measurement in the office, at home and ambulatory blood pressure (ABP) in children with arterial hypertension

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    O diagnóstico e acompanhamento da hipertensão arterial (HA) no paciente pediátrico dependem da acurácia e da representatividade da medida da pressão arterial (PA). A monitorização ambulatorial da pressão arterial (MAPA), apesar de suas vantagens em relação à medida casual, apresenta custo elevado e pode trazer desconforto ao paciente. A medida residencial da pressão arterial (MRPA), apesar de pouco estudada na criança, apresenta-se como um alternativo potencial à MAPA. Os objetivos deste estudo foram comparar as medidas da PA aferidas no consultório, na MRPA, na Liga de Hipertensão e pela MAPA avaliando o efeito do ambiente/observador e determinando a freqüência de valores compatíveis com HA nessas 4 situações. Este estudo foi transversal,prospectivo e foram incluídos pacientes com HA e PA controlada ou não no consultório. Foram analisadas as médias das pressões arteriais sistólicas e diastólicas. A MRPA foi realizada com aparelho OMRON HEM 705 CP por 14 dias, em dois períodos (manhã ou tarde e noite). Na véspera do início da MRPA, o paciente compareceu à Liga de Hipertensão do HC-FMUSP para colocação do equipamento da MAPA (SPACELABS 90207). Foram analisados os dados de 40 pacientes (14 meninas e 26 meninos), idade média 12,1±3,6 anos. Não houve diferença estatística entre as médias das pressões sistólicas (ANOVA p=0,3100) e diastólicas (ANOVA p=0,7700) no consultório com as médias diurnas da MRPA e nem com as médias sistólicas (ANOVA p=0,8240) e diastólicas(ANOVA p=0,1530) do período noturno da MRPA. As médias das pressões sistólicas e diastólicas da Liga e da MAPA foram maiores do que as médias do consultório e da MRPA (p0,05). Na MAPA sono, os pacientes apresentaram maior freqüência de PA controlada do que na MRPA noturna. Dez pacientes apresentaram PA não controlada no consultório, a MAPA confirmou o diagnóstico em 7/10 (17,5%) pacientes, enquanto 5/10 (12,5%) confirmaram pela MRPA. Nesse grupo, a hipertensão do avental branco ocorreu em 3/10 (7,5%) pacientes diagnosticados pela MAPA e em 5/10 (12,5%) diagnosticados pela MRPA.Trinta pacientes apresentaram valores de PA controlados no consultório, destes 24/30 (60%) pacientes confirmaram o diagnóstico pela MAPA e 26/30 (65%) pela MRPA. A hipertensão mascarada ocorreu em 6/30 (15%) pacientes diagnosticados pela MAPA e em 4/30 (10%) diagnosticados pela MRPA. Nesse estudo demonstrou-se concordância entre MAPA e MRPA (teste de Mc Nemar p 0.05). The BP measurements during nightime ABPM showed a higher frequency of values compatible with hypertension than the night HBP one. Ten patients were diagnosed hypertension in the office, ABPM confirmed the diagnosis in 7 / 10 (17.5%) patients, while 5 / 10 (12.5%) were confirmed by HBP. In this group, white-coat hypertension occurred in 3 / 10 (7.5%) patients as diagnosed by the ABPM and 5 / 10 (12.5%) as diagnosed by HBP.Thirty patients presented BP values within normal limits in the office, 24 / 30 (60%) patients confirmed this diagnosis by ABPM and 26/30 (65%) by HBP. Masked hypertension was diagnosed in 6 / 30 (15%) patients diagnosed by the ABPM and in 4 / 30 (10%) by HBP. This study confirmed a correlation between ABPM and HBP measurements (Mc Nemar test p <0.01) with good reproducibility as evaluated by the Kappa index (0.557)
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