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1.
Opt Express ; 31(16): 25515-25526, 2023 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-37710436

RESUMO

We demonstrated all-silicon IQ modulators (IQMs) operating at 120-GBaud 16-QAM with suitable bandwidth, and output power. We required optical signal-to-noise-ratio (rOSNR) that have promising potential to be used in 800-Gbps small-form-factor pluggable transceivers for data center interconnection. First, we tested an IQM chip using discrete drivers and achieved a per-polarization TX output power of -18.74 dBm and an rOSNR of 23.51 dB over a 100-km standard SMF. Notably, a low BER of 1.4e-3 was obtained using our SiP IQM chip without employing nonlinear compensation, optical equalization, or an ultra-wide-bandwidth, high-ENOB OMA. Furthermore, we investigated the performance of a 3D packaged transmitter by emulating its frequency response using an IQM chip, discrete drivers, and a programmable optical filter. With a laser power of 17 dBm, we achieved a per-polarization output power of -15.64 dBm and an rOSNR of 23.35 dB.

2.
Curr Microbiol ; 80(9): 284, 2023 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-37450067

RESUMO

Gamma-aminobutyric acid (GABA) is considered as a potential candidate substance that mediates the effects of intestinal bacteria on human mental health. In the present study, we evaluated the effect of water-soluble cellulose acetate (WSCA), a type of cellulose ester, on fermentation and microbial profiles, and GABA production in human stool cultures prepared from fresh feces from volunteers. In addition, the GABA-producing ability of Bacteroides uniformis, which can utilize WSCA, was evaluated in a pure-culture study. All incubations were conducted anaerobically. WSCA supplementation increased (P < 0.05) acetate and propionate production and decreased (P < 0.05) the pH in human fecal cultures. WSCA significantly altered the microbiota, selectively increasing the relative abundance of B. uniformis (P < 0.05). Pure-culture study results revealed that B. uniformis produces GABA, possibly via a glutamate-dependent acid resistance system under low pH conditions. In conclusion, WSCA could be a potential prebiotic material that is fermented by intestinal bacteria and increases short-chain fatty acid and GABA production in the human gut. Bacteroides uniformis might play an important role in both WSCA degradation and GABA production in the intestine.


Assuntos
Celulose , Microbiota , Humanos , Fermentação , Fezes/microbiologia , Acetatos , Ácido gama-Aminobutírico
3.
Digestion ; 103(3): 217-223, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35172301

RESUMO

INTRODUCTION: Helicobacter pylori (HP) infection causes chronic inflammation and atrophy of the gastric mucosa and thus a high risk of gastric cancer (GC). With the increasing success of HP infection treatment, a larger number of GCs that develop after eradication can be assessed. Several studies have shown that epithelium with low-grade atypia (ELA) is a frequent characteristic of these GCs, but the origin of this condition is unknown. In this study, we compared the mucin phenotype, cellular proliferation, and p53 staining in ELA and cancerous tissues obtained from patients with GC with and without HP eradication. METHODS: The study population consisted of 23 patients with GC that developed after successful HP eradication therapy (eradicated group) and 24 patients with GC and HP infection (infected group). The prevalence of ELA was determined by hematoxylin and eosin staining. Tumor tissue and ELA samples were further analyzed by immunohistochemical staining for Muc5AC, Muc2, p53, and Ki-67. RESULTS: The ELA coverage rate was significantly higher in the eradicated group than in the infected group. Gastric-type mucin was frequently expressed by the ELA, and the mucin phenotypes of ELA and cancerous areas differed in 75% of cases. The Ki-67 labeling index was consistently lower in ELA than in the cancerous mucosa. Fourteen of 21 (66.7%) cancerous lesions, but only 3 ELA samples, were p53-positive. CONCLUSION: In most cases, ELA on the surfaces of GCs seems to have originated from normal gastric cells, not from cancer cells.


Assuntos
Infecções por Helicobacter , Helicobacter pylori , Neoplasias Gástricas , Epitélio/patologia , Mucosa Gástrica/patologia , Infecções por Helicobacter/complicações , Infecções por Helicobacter/tratamento farmacológico , Infecções por Helicobacter/patologia , Humanos , Antígeno Ki-67 , Neoplasias Gástricas/etiologia , Neoplasias Gástricas/patologia , Proteína Supressora de Tumor p53
4.
J Clin Pharm Ther ; 47(8): 1264-1269, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35470461

RESUMO

WHAT IS KNOWN AND OBJECTIVE: Compared with the general adult population, pharmacokinetics and changes in drug responsiveness occur to a greater extent in the elderly. Interactions may occur between drugs used in combination to treat various diseases and may cause adverse events (AEs). We conducted a cross-sectional risk assessment of AEs in elderly patients based on information gathered from Japanese medical practices with the goal of obtaining information that will contribute to optimizing pharmacotherapy. METHODS: The Japanese Adverse Drug Event Report database was used to determine the incidence of AEs in elderly patients (aged 80 years or older) compared with patients aged less than 80 years old by evaluating the reporting odds ratio using the data obtained from reports. RESULTS AND DISCUSSION: Hypnotics and anxiolytics, as well as anticoagulants and theophylline, were identified as groups of drugs that warrant special attention in the elderly. Hypnotics and anxiolytics, especially those that are short-acting, tend to cause delirium and geriatric syndromes including falls and fractures. With respect to anticoagulants, no increase in the risk of bleeding was evident and the dose was believed to be properly adjusted; however, there was an increased risk of anemia. Theophylline toxicity tended to occur more frequently in the elderly, suggesting the need for drug monitoring. WHAT IS NEW AND CONCLUSION: Based on these cross-sectional studies, the evaluation of the risk of AEs for drugs commonly used in the elderly based on near real-world information was achieved.


Assuntos
Ansiolíticos , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos , Idoso , Idoso de 80 Anos ou mais , Anticoagulantes , Estudos Transversais , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos/epidemiologia , Humanos , Hipnóticos e Sedativos , Japão/epidemiologia , Teofilina
5.
Molecules ; 27(15)2022 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-35956860

RESUMO

Pancreatic lipase catalyzes the cleavage of triacylglycerols at the oil-water interface, and is known as the dominant determiner of dietary fat digestion. Reducing dietary fat digestion and absorption by modulating the activity of pancreatic lipase has become a favorable strategy to tackle obesity. Orlistat is, at present, the only pancreatic lipase inhibitor approved for the treatment of obesity; however, an array of gastrointestinal adverse effects associated with orlistat limits its tolerability. As a safe alternative to orlistat, a number of natural product-derived compounds with varying degrees of pancreatic lipase inhibitory activity have been reported. We herein reported that bioactivity-guided fractionation of sesame meal led to the identification of free linoleic acid and oleic acid as potent inhibitors of porcine pancreatic lipase in vitro with an IC50 of 23.1 µg/mL (82.4 µM) and 11.7 µg/mL (41.4 µM), respectively. In rats, a single oral dose of the mixture of these fatty acids significantly suppressed the elevation of blood triacylglycerol level following fat intake. These results substantiate the role of free linoleic acid and oleic acid as a novel class of natural product-derived functional molecules that act as pancreatic lipase inhibitors, and their potential for healthy, routine-based weight management.


Assuntos
Produtos Biológicos , Sesamum , Animais , Produtos Biológicos/uso terapêutico , Gorduras na Dieta , Digestão , Ácido Linoleico/farmacologia , Lipase , Obesidade/tratamento farmacológico , Ácido Oleico/farmacologia , Orlistate/farmacologia , Ratos , Suínos , Triglicerídeos
6.
Biochemistry ; 60(41): 3058-3070, 2021 10 19.
Artigo em Inglês | MEDLINE | ID: mdl-34609135

RESUMO

Retinal guanylate cyclases (RetGCs) are regulated by a family of guanylate cyclase-activating proteins (called GCAP1-7). GCAPs form dimers that bind to Ca2+ and confer Ca2+ sensitive activation of RetGC during visual phototransduction. The GCAP5 homologue from zebrafish contains two nonconserved cysteine residues (Cys15 and Cys17) that bind to ferrous ion, which stabilizes GCAP5 dimerization and diminishes its ability to activate RetGC. Here, we present NMR and EPR-DEER structural analysis of a GCAP5 dimer in the Mg2+-bound, Ca2+-free, Fe2+-free activator state. The NMR-derived structure of GCAP5 is similar to the crystal structure of Ca2+-bound GCAP1 (root-mean-square deviation of 2.4 Å), except that the N-terminal helix of GCAP5 is extended by two residues, which allows the sulfhydryl groups of Cys15 and Cys17 to become more solvent exposed in GCAP5 to facilitate Fe2+ binding. Nitroxide spin-label probes were covalently attached to particular cysteine residues engineered in GCAP5: C15, C17, T26C, C28, N56C, C69, C105, N139C, E152C, and S159C. The intermolecular distance of each spin-label probe in dimeric GCAP5 (measured by EPR-DEER) defined restraints for calculating the dimer structure by molecular docking. The GCAP5 dimer possesses intermolecular hydrophobic contacts involving the side chain atoms of H18, Y21, M25, F72, V76, and W93, as well as an intermolecular salt bridge between R22 and D71. The structural model of the GCAP5 dimer was validated by mutations (H18E/Y21E, H18A/Y21A, R22D, R22A, M25E, D71R, F72E, and V76E) at the dimer interface that disrupt dimerization of GCAP5 and affect the activation of RetGC. We propose that GCAP5 dimerization may play a role in the Fe2+-dependent regulation of cyclase activity in zebrafish photoreceptors.


Assuntos
Proteínas Ativadoras de Guanilato Ciclase/química , Proteínas de Peixe-Zebra/química , Sequência de Aminoácidos , Animais , Cisteína/química , Espectroscopia de Ressonância de Spin Eletrônica , Proteínas Ativadoras de Guanilato Ciclase/genética , Proteínas Ativadoras de Guanilato Ciclase/metabolismo , Magnésio/química , Magnésio/metabolismo , Simulação de Acoplamento Molecular , Mutação , Ressonância Magnética Nuclear Biomolecular , Ligação Proteica , Multimerização Proteica , Estrutura Quaternária de Proteína , Peixe-Zebra , Proteínas de Peixe-Zebra/genética , Proteínas de Peixe-Zebra/metabolismo
7.
J Sci Food Agric ; 101(7): 2950-2960, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33159326

RESUMO

BACKGROUND: Water-soluble cellulose acetate (WSCA), a synthetic fiber source, was applied to human stool cultures and to pure cultures of representative Bacteroides species to characterize the fermentation properties of WSCA in the human gut, and to assess the potential availability of WSCA as a food or additive candidate. RESULTS: All nine of the different types of WSCA tested here provided increased acetate levels in human stool cultures. Greater levels of deacetylation were observed as the degree of substitution of hydroxyl groups by acetyl groups decreased. Among the nine tested types of WSCA, CA-0.78-128 caused the largest shifts of the microbial community, including an increased abundance of members of the genus Bacteroides, especially Bacteroides uniformis. Of four representative human gut Bacteroides species, only B. uniformis grew in pure culture on WSCA to produce acetate actively. CONCLUSION: Water-soluble cellulose acetate has the potential for dietary application in human and other monogastric animals, based on the enhanced production of short-chain fatty acids (SCFAs), in particular acetate, in the hindgut. Short-chain fatty acid production is caused by selective proliferation of specific gut bacteria belonging to the genus Bacteroides. © 2020 Society of Chemical Industry.


Assuntos
Bactérias/metabolismo , Celulose/análogos & derivados , Fezes/microbiologia , Microbioma Gastrointestinal , Animais , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Celulose/metabolismo , Fibras na Dieta/metabolismo , Ácidos Graxos Voláteis/metabolismo , Fermentação , Humanos , Prebióticos/análise
8.
BMC Gastroenterol ; 18(1): 4, 2018 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-29310576

RESUMO

CORRECTION: Unfortunately, the original article [1] contained an error incorporated during production. A duplicated version of Table 1 was published in place of Table 2. Table 2 has been corrected in the original article and is also included correctly below.

9.
Cancer Sci ; 108(11): 2156-2165, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28837246

RESUMO

Pancreatic ductal adenocarcinoma (PDAC) is a life-threatening disease and there is an urgent need to develop improved therapeutic approaches. The role of c-Jun N-terminal kinase (JNK) in PDAC stroma is not well defined even though dense desmoplastic reactions are characteristic of PDAC histology. We aimed to explore the role of JNK in PDAC stroma in mice. We crossed Ptf1aCre/+ ;KrasG12D/+ mice with JNK1-/- mice to generate Ptf1aCre/+ ;KrasG12D/+ ;JNK1-/- (Kras;JNK1-/- ) mice. Tumor weight was significantly lower in Kras;JNK1-/- mice than in Kras;JNK1+/- mice, whereas histopathological features were similar. We also transplanted a murine PDAC cell line (mPC) with intact JNK1 s.c. into WT and JNK1-/- mice. Tumor diameters were significantly smaller in JNK1-/- mice. Phosphorylated JNK (p-JNK) was activated in α-smooth muscle actin (SMA)-positive cells in tumor stroma, and mPC-conditioned medium activated p-JNK in tumor-associated fibroblasts (TAF) in vitro. Relative expression of Ccl20 was downregulated in stimulated TAF. Ccl20 is an important chemokine that promotes CD8+ T-cell infiltration by recruitment of dendritic cells, and the number of CD8+ T cells was decreased in Kras;JNK1+/- mice compared with Kras;JNK1-/- mice. These results suggest that the cancer secretome decreases Ccl20 secretion from TAF by activation of JNK, and downregulation of Ccl20 secretion might be correlated with reduction of infiltrating CD8+ T cells. Therefore, we concluded that inhibition of activated JNK in pancreatic tumor stroma could be a potential therapeutic target to increase Ccl20 secretion from TAF and induce accumulation of CD8+ T cells, which would be expected to enhance antitumor immunity.


Assuntos
Adenocarcinoma/genética , Carcinoma Ductal Pancreático/genética , Quimiocina CCL20/genética , Proteínas Quinases JNK Ativadas por Mitógeno/genética , Proteínas Proto-Oncogênicas p21(ras)/genética , Fatores de Transcrição/genética , Adenocarcinoma/patologia , Animais , Linfócitos T CD8-Positivos/metabolismo , Linfócitos T CD8-Positivos/patologia , Fibroblastos Associados a Câncer/metabolismo , Fibroblastos Associados a Câncer/patologia , Carcinoma Ductal Pancreático/patologia , Regulação Neoplásica da Expressão Gênica , Humanos , Camundongos , Mutação , Células-Tronco Neoplásicas/patologia , Transdução de Sinais/genética
10.
BMC Gastroenterol ; 17(1): 145, 2017 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-29212456

RESUMO

BACKGROUND: Although Helicobacter-induced gastric inflammation is the major predisposing factor for gastric carcinogenesis, the precise mechanism by which chronic gastritis causes gastric cancer remains unclear. Intestinal and spasmolytic polypeptide-expressing metaplasia (SPEM) is considered as precancerous lesions, changes in epithelial tissue stem/progenitor cells after chronic inflammation has not been clarified yet. In this study, we utilized three-dimensional gastric epithelial cell culture systems that could form organoids, mimicking gastric epithelial layer, and characterized the changes in epithelial cells after chronic Helicobacter felis infection. METHODS: We used three mice model; 1) long-term H. felis infection, 2) H. felis eradication, and 3) MNU chemical carcinogenesis model. We performed cRNA microarray analysis after organoid culture, and analyzed the effects of chronic gastric inflammation on tissue stem cells, by the size of organoid, mRNA expression profile and immunohistochemical analysis. RESULTS: The number of organoids cultured from gastric epithelial cells was significantly higher in organoids isolated from H. felis-infected mice compared with those from uninfected gastric mucosa. Based on the mRNA expression profile, we found that possible stem cell markers such as Cd44, Dclk1, and genes associated with the intestinal phenotype, such as Villin, were increased in organoids isolated from H. felis-infected mucosa compared with the control. The upregulation of these genes were cancelled after H. felis eradication. In a xenograft model, tumors were generated only from organoids cultured from carcinogen-treated gastric mucosa, not from H. felis infected mucosa or control organoids. CONCLUSIONS: Our results suggested that, as a possible mechanism of gastric carcinogenesis, chronic inflammation induced by H. felis infection increased the number of tissue stem/progenitor cells and the expression of stem cell markers. These findings suggest that chronic inflammation may alter the direction of differentiation toward undifferentiated state and that drawbacks may enable cells to redifferentiate to intestinal metaplasia or neoplasia.


Assuntos
Mucosa Gástrica/patologia , Gastrite/patologia , Infecções por Helicobacter/patologia , Células-Tronco/patologia , Animais , Carcinogênese , Contagem de Células , Proliferação de Células , Doença Crônica , Citocinas/metabolismo , Modelos Animais de Doenças , Mucosa Gástrica/metabolismo , Gastrite/metabolismo , Expressão Gênica , Infecções por Helicobacter/metabolismo , Helicobacter felis , Masculino , Camundongos Endogâmicos C57BL , Organoides/metabolismo , RNA Mensageiro/genética , Neoplasias Gástricas/microbiologia , Neoplasias Gástricas/patologia
11.
Inorg Chem ; 55(1): 7-9, 2016 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-26678346

RESUMO

Two new porphycenes functionalized with ferrocenyl pendants have been synthesized and characterized spectroscopically and structurally. The porphycene-based emission in porphycene-ferrocene dyads was switched on and off by the reversible control of the ferrocenyl pendant redox states. Transient absorption spectroscopy with a femtosecond laser-pulsed technique has successfully detected the picosecond charge-separated excited state of the dyad upon Q-band excitation of the porphycene ring.

12.
ScientificWorldJournal ; 2014: 645734, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25298969

RESUMO

This study presents a new modulation method for multidirectional matrix converter (MDMC), based on the direct duty ratio pulse width modulation (DDPWM). In this study, a new structure of MDMC has been proposed to control the power flow direction through the stand-alone battery based system and hybrid vehicle. The modulation method acts based on the average voltage over one switching period concept. Therefore, in order to determine the duty ratio for each switch, the instantaneous input voltages are captured and compared with triangular waveform continuously. By selecting the proper switching pattern and changing the slope of the carriers, the sinusoidal input current can be synthesized with high power factor and desired output voltage. The proposed system increases the discharging time of the battery by injecting the power to the system from the generator and battery at the same time. Thus, it makes the battery life longer and saves more energy. This paper also derived necessary equation for proposed modulation method as well as detail of analysis and modulation algorithm. The theoretical and modulation concepts presented have been verified in MATLAB simulation.


Assuntos
Algoritmos , Fontes de Energia Elétrica/normas , Eletricidade , Modelos Teóricos , Simulação por Computador , Desenho de Equipamento , Humanos , Reprodutibilidade dos Testes
13.
Phys Rev E ; 107(6): L062201, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-37464610

RESUMO

By using the kicked Harper model, the effect of dynamical perturbations to the localized and ballistic phases in quasiperiodic lattice systems is investigated. The transition from the localized phase to diffusive phase via a critical subdiffusion t^{α} (t is time) with 0<α<1 is observed. In addition, we confirm the existence of the transition from the ballistic phase to the diffusive phase via a critical superdiffusion with 1<α<2.

14.
J Hand Surg Asian Pac Vol ; 28(4): 502-506, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37758488

RESUMO

Haemosiderotic synovitis (HS) is a rare synovial proliferative disease secondary to haemarthrosis, often with articular cartilage destruction. It is most frequently reported in patients with haemophiliacs, and the knee joint is most frequently affected. However, there are no reports on the elbow joint without haemophiliacs. A 60-year-old woman who had undergone osteosynthesis for a left radial head fracture 8 years earlier came to our clinic with left elbow pain. X-rays and CT scans showed osteopenia and osteoarthritic changes throughout the elbow joint. MRI revealed joint effusion and synovial membrane hyperplasia. Surgical synovectomy and screw removal were performed. The pathological diagnosis of the synovial membrane was HS. Postoperatively, the pain was relieved, osteopenia improved and there was no recurrence of symptoms. This is the first report of non-haemophilic HS of the elbow; post-traumatic HS caused elbow arthropathy, which was improved by screw removal and synovectomy. Level of Evidence: Level V (Therapeutic).

15.
J Med Food ; 26(5): 299-306, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-37074675

RESUMO

Collagen-derived dipeptides and tripeptides have various physiological activities. In this study, we compared the plasma kinetics of free Hyp, peptide-derived Hyp, Pro-Hyp, cyclo(Pro-Hyp), Hyp-Gly, Gly-Pro-Hyp, and Gly-Pro-Ala after ingestion of four different collagen samples: AP collagen peptide (APCP), general collagen peptide, collagen, and APCP and γ-aminobutyric acid (GABA) combination. Each peptide was measured by high-performance liquid chromatography and triple quadrupole mass spectrometer. We found that, among all the peptides that were analyzed, only Gly-Pro-Hyp was significantly increased after ingestion of APCP compared with that of general collagen peptides and collagen. In addition, ingestion of the APCP and GABA combination improved the absorption efficiency of Gly-Pro-Ala. Finally, we reveal that Gly-Pro-Hyp was effective for preventing H2O2-induced reduction in extracellular matrix (ECM)-related genes, COL1A, elastin, and fibronectin, in dermal fibroblasts. Taken together, APCP significantly enhances the absorption of Gly-Pro-Hyp, which might act as an ECM-associated signaling factor in dermal fibroblasts, and the APCP and GABA combination promotes Gly-Pro-Ala absorption. Clinical Trial Registration number: UMIN000047972.


Assuntos
Colágeno , Fibroblastos , Peróxido de Hidrogênio , Peptídeos , Absorção Fisiológica , Colágeno/administração & dosagem , Colágeno/química , Ingestão de Alimentos , Fibroblastos/metabolismo
16.
Nutrients ; 15(7)2023 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-37049588

RESUMO

A great number of chemically diverse pancreatic lipase (PL) inhibitors have been identified to tackle obesity; however, very few of them have entered clinical studies. The ethanolic extract of sesame meal is a potent PL inhibitor, and its activity hinges exclusively on two free fatty acids: linoleic acid and oleic acid, which were proven to reduce postprandial triglyceride excursion in rats. Herein, to investigate the clinical efficacy of the sesame meal extract, in a crossover trial, 30 healthy volunteers were randomized to receive the sesame meal extract containing experimental food or placebo along with a high-fat meal. Treatment with the sesame meal extract significantly lowered the incremental postprandial serum triglyceride concentration and reduced the incremental area under the curve (iAUC) by 16.8% (p-value = 0.03) compared to placebo. Significant decreases in postprandial remnant-like lipoprotein particle cholesterol and low-density lipoprotein particles were also observed, whereas high-density lipoprotein cholesterol was increased. These results suggest that treatment with the sesame meal extract significantly reduced the postprandial excursion of triglycerides and improved the lipidemic profile after high dietary fat intake in healthy individuals, indicating the substantial potential of free linoleic acid and oleic acid and natural products rich in these compounds for the management of obesity and related conditions.


Assuntos
Ácido Oleico , Sesamum , Animais , Ratos , Humanos , Estudos Cross-Over , Ácido Oleico/farmacologia , Ácido Linoleico/farmacologia , Lipase , Voluntários Saudáveis , Triglicerídeos , Colesterol , Obesidade , Período Pós-Prandial , Gorduras na Dieta
17.
Phys Rev E ; 105(5-1): 054201, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35706293

RESUMO

Localization and delocalization of quantum diffusion in a time-continuous one-dimensional Anderson model perturbed by the quasiperiodic harmonic oscillations of M colors is investigated systematically, which has been partly reported by a preliminary Letter [H. S. Yamada and K. S. Ikeda, Phys. Rev. E 103, L040202 (2021)2470-004510.1103/PhysRevE.103.L040202]. We investigate in detail the localization-delocalization characteristics of the model with respect to three parameters: the disorder strength W, the perturbation strength ε, and the number of colors, M, which plays the similar role of spatial dimension. In particular, attention is focused on the presence of localization-delocalization transition (LDT) and its critical properties. For M≥3 the LDT exists and a normal diffusion is recovered above a critical strength ε, and the characteristics of diffusion dynamics mimic the diffusion process predicted for the stochastically perturbed Anderson model even though M is not large. These results are compared with the results of discrete-time quantum maps, i.e., the Anderson map and the standard map. Further, the features of delocalized dynamics are discussed in comparison with a limit model which has no static disordered part.

18.
Phys Rev E ; 103(4): L040202, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-34005878

RESUMO

A new type of delocalization induced by coherent harmonic perturbations in one-dimensional Anderson-localized disordered systems is investigated. With only a few M frequencies a normal diffusion is realized, but the transition to a localized state always occurs as the perturbation strength is weakened below a critical value. The nature of the transition qualitatively follows the Anderson transition (AT) if the number of degrees of freedom M+1 is regarded as the spatial dimension d. However, the critical dimension is found to be d=M+1=3 and is not d=M+1=2, which should naturally be expected by the one-parameter scaling hypothesis.

19.
Phys Rev E ; 101(3-1): 032210, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32289890

RESUMO

Following the paper exploring the Anderson localization of monochromatically perturbed kicked quantum maps [Phys. Rev. E 97, 012210 (2018)2470-004510.1103/PhysRevE.97.012210], the delocalization-localization transition phenomena in polychromatically perturbed quantum maps (QM) is investigated focusing particularly on the dependency of critical phenomena on the number M of the harmonic perturbations, where M+1=d corresponds to the spatial dimension of the ordinary disordered lattice. The standard map and the Anderson map are treated and compared. As the basis of analysis, we apply the self-consistent theory (SCT) of the localization for our systems, taking a plausible hypothesis on the mean-free-path parameter which worked successfully in the analyses of the monochromatically perturbed QMs. We compare in detail the numerical results with the predictions of the SCT by largely increasing M. The numerically obtained index of critical subdiffusion t^{α} (t:time) agrees well with the prediction of one-parameter scaling theory α=2/(M+1), but the numerically obtained critical exponent of localization length significantly deviates from the SCT prediction. Deviation from the SCT prediction is drastic for the critical perturbation strength of the transition: If M is fixed, then the SCT presents plausible prediction for the parameter dependence of the critical value, but its value is 1/(M-1) times smaller than the SCT prediction, which implies existence of a strong cooperativity of the harmonic perturbations with the main mode.

20.
J Theor Biol ; 256(3): 351-69, 2009 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-19014957

RESUMO

We study intrinsic properties of attractor in Boolean dynamics of complex networks with scale-free topology, comparing with those of the so-called Kauffman's random Boolean networks. We numerically study both frozen and relevant nodes in each attractor in the dynamics of relatively small networks (20

Assuntos
Simulação por Computador , Regulação da Expressão Gênica , Redes Reguladoras de Genes , Modelos Genéticos , Animais , Humanos , Dinâmica não Linear
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