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1.
Artigo em Inglês | MEDLINE | ID: mdl-35483787

RESUMO

Telomeres play a critical role in maintaining cellular fate through tight regulation of cell division and DNA damage or repair. Over the years, it is established that biological ageing is defined by a gradual derangement in functionality, productivity, and robustness of biological processes. The link between telomeres and ageing is highlighted when derangement in telomere biology often leads to premature ageing and concomitant accompaniment of numerous age-associated diseases. Unfortunately, given that ageing is a biologically complicated intricacy, measures to reduce morbidity and improve longevity are still largely in the infancy stage. Recently, it was discovered that dietary habits and interventions might play a role in promoting successful healthy ageing. The intricate relationship between dietary components and its potential to protect the integrity of telomeres may provide unprecedented health benefits and protection against age-related pathologies. However, more focused prospective and follow-up studies with and without interventions are needed to unequivocally link dietary interventions with telomere maintenance in humans. This review aims to summarise recent findings that investigate the roles of nutrition on telomere biology and provide enough evidence for further studies to consider the topic of nutrigenomics and its contributions toward healthy ageing and concomitant strategy against age-associated diseases.


Assuntos
Dano ao DNA , Telômero , Dieta , Humanos , Estudos Prospectivos , Telômero/genética
2.
Osteoarthritis Cartilage ; 28(5): 613-625, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32006659

RESUMO

OBJECTIVES: Monocyte-derived macrophages, as the predominant immune cell type that is increased in inflamed synovium, play a vital role during knee osteoarthritis (KOA) progression. However, the mechanisms underlying the recruitment of circulating monocytes to osteoarthritic knees remain uncertain. Based on previous data obtained from plasma, we investigated the contributions of CCL2, CCL3, CCL4 and their cognate receptors in circulating monocyte chemotaxis and KOA development. METHODS: Using flow cytometry staining, we characterized the expression patterns of the chemokine receptors in CD14+CD16- circulating monocytes from KOA patients and healthy volunteers. The expression of chemokines in synovial fluids, synovium and cartilage was investigated in KOA patients and in patients without KOA. The role of chemokines and their cognate receptors in the chemotaxis of CD14+CD16- circulating monocytes was assessed using chemokine neutralizing antibodies (NA) and receptor antagonists in vitro and in vivo. RESULTS: The majority of CD14+CD16- circulating monocytes were CCR1-and CCR2-positive. CCL2, CCL3 and CCL4 were elevated in synovial fluid of KOA patients compared with that of controls. The most likely source of these chemokines is inflamed synovium and cartilage in the osteoarthritic knee. The CCL3/CCR1 and CCL2/CCR2 axes showed substantial ability to recruit CD14+CD16- monocytes in transwell assays. Similar results were confirmed in a mouse model of collagenase-induced KOA (CIA) in which blocking either the CCL3/CCR1 axis or the CCL2/CCR2 axis reduced synovial hyperplasia and F4/80+ macrophage infiltration. CONCLUSIONS: Our findings suggested that, analogous to the CCL2/CCR2 axis, CCL3 produced in osteoarthritic knees can chemoattract circulating monocytes to the inflamed synovium through CCR1.


Assuntos
Quimiocinas CC/imunologia , Quimiotaxia de Leucócito/imunologia , Macrófagos/imunologia , Monócitos/imunologia , Osteoartrite do Joelho/imunologia , Receptores de Quimiocinas/imunologia , Adulto , Idoso , Cartilagem Articular/imunologia , Estudos de Casos e Controles , Quimiocina CCL2/imunologia , Quimiocina CCL3/imunologia , Quimiocina CCL4/imunologia , Progressão da Doença , Feminino , Humanos , Receptores de Lipopolissacarídeos , Masculino , Pessoa de Meia-Idade , Receptores CCR1/imunologia , Receptores CCR2/imunologia , Receptores CCR5/imunologia , Receptores de IgG , Líquido Sinovial/imunologia , Membrana Sinovial/imunologia
3.
Eur Rev Med Pharmacol Sci ; 21(23): 5408-5414, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29243783

RESUMO

OBJECTIVE: To investigate the prevalence rate of nutritional risk in high-risk stroke groups in community, analyze its influencing factors, and analyze and compare the relationship between nutritional risk or malnutrition assessed by different nutritional evaluation methods and cognitive function, so as to provide the basis and guidance for clinical nutritional assessment and support. PATIENTS AND METHODS: A cross-sectional survey was performed for 1196 cases in high-risk stroke groups in community from December 2015 to January 2017. At the same time, the nutritional status of patients was evaluated using the mini nutritional assessment (MNA) and MNA-short form (MNA-SF), and the cognitive status of patients was evaluated using the mini-mental state examination (MMSE). Moreover, the relevant influencing factors of nutritional risk and MMSE score were analyzed and compared. RESULTS: High-risk stroke groups in community suffered from a high risk of malnutrition. MNA-SF had a higher specificity and lower false positive rate than MNA. Nutritional risk occurred more easily in high-risk stroke groups in community with a history of diabetes mellitus, less physical exercise or light manual labor, daily use of multiple drugs, and higher age. Those with a higher nutritional risk were more prone to cognitive impairment. High-risk stroke groups in community, complicated with hyperhomocysteinemia, daily use of three or more kinds of prescription drugs, and a previous history of stroke, were accompanied by cognitive impairment easily. CONCLUSIONS: MNA-SF can be used for the nutritional screening of high-risk stroke groups in community. For the high-risk stroke groups in community, the rational nutritional diet should be publicized, blood sugar should be controlled in a scientific manner and physical exercise should be moderately increased.


Assuntos
Disfunção Cognitiva/epidemiologia , Desnutrição/epidemiologia , Acidente Vascular Cerebral/complicações , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Avaliação Nutricional , Fatores de Risco
4.
Phys Rev Lett ; 119(14): 147002, 2017 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-29053311

RESUMO

By dual gating a few-layer MoS_{2} flake, we induce spatially separated electronic states showing superconductivity and Shubnikov-de Haas (SdH) oscillations. While the highly confined superconductivity forms at the K/K^{'} valleys of the topmost layer, the SdH oscillations are contributed by the electrons residing in the Q/Q^{'} valleys of the rest of the bottom layers, which is confirmed by the extracted Landau level degeneracy of 3, electron effective mass of 0.6m_{e}, and carrier density of 5×10^{12} cm^{-2}. Mimicking conventional heterostructures, the interaction between the heteroelectronic states can be electrically manipulated, which enables "bipolarlike" superconducting transistor operation. The off-on-off switching pattern can be continuously accessed at low temperatures by a field effect depletion of carriers with a negative back gate bias and the proximity effect between the top superconducting layer and the bottom metallic layers that quenches the superconductivity at a positive back gate bias.

5.
Artigo em Chinês | MEDLINE | ID: mdl-28780820

RESUMO

Objective: To investigate the interaction between mental elasticityand occupational stress and depressionin female nurses and the mediating effect of mental elasticity, as well as the functioning way of mental elasticity in occupational stress-depression. Methods: From August to October, 2015, cluster sampling was used to select 122 female nurses in a county-level medical institution as study subjects. The Connor-Davidson Resilience Scale (CD-RISC) , Occupational Stress Inventory-Revised Edition (OSI-R) , and Self-Rating Depression Scale (SDS) were used to collect the data on mental elasticity, occupational stress, and depression and analyze their correlation and mediating effect. Results: The 122 female nurses had a mean mental elasticity score of 62.4±15.1, which was significantly lower than the Chinese norm (65.4±13.9) (P<0.05) ; the mean depression score was 41.0±7.7, which was significantly higher than the Chinese norm (33.5±8.6) (P<0.01) , and the incidence rate of depression of 52.5%. Mental elasticity was negatively correlated with occupational stress and depression (r=-0.559 and -0.559, both P<0.01) . Occupational stress and the two subscales mental stress reaction and physical stress reaction were positively correlated with depression (r=0.774, 0.734, and 0.725, all P<0.01) . After adjustment for confounding factors, occupational stress had a positive predictive effect on depression (ß=0.744, P<0.01) , and mental elasticity had a negative predictive effect on depression (ß=-0.221, P<0.01) . The analysis of mediating effect showed a significant direct effect of occupational stress on depression and a significant mediating effect of mental elasticity (a=-0.527, b=-0.227, c=0.744, c'=0.627; all P<0.01) , and the mediating effect of mental elasticity accounted for 16.08% of the total effect. Conclusion: As a partial mediating variable, mental elasticity has an indirect effect on the relationship between occupational stress and depression and can alleviate the adverse effect of occupational stress and reduce the development of depression.


Assuntos
Depressão/psicologia , Enfermeiras e Enfermeiros/psicologia , Estresse Ocupacional/psicologia , Feminino , Humanos , Enfermeiras e Enfermeiros/estatística & dados numéricos , Escalas de Graduação Psiquiátrica
6.
Clin Exp Dermatol ; 42(5): 509-515, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28543665

RESUMO

BACKGROUND: Symmetrical acrokeratoderma (SAK) is characterized by brown to black hyperkeratotic patches on acral regions. Although epidermal hyperkeratosis and acanthosis are consistent pathological changes, the nature of epidermal hyperplasia is unknown. AIM: To evaluate epidermal proliferation and differentiation and melanocytic density in skin lesions of SAK. METHODS: Expression of keratin 10 (K10), K14, K16, involucrin, filaggrin, Ki-67, and Melan-A was detected by immunohistochemistry in eight patients with SAK, seven patients with ichthyosis vulgaris (IV) and six healthy controls (HCs). RESULTS: Expression of K14, K16, involucrin and filaggrin was upregulated in patients with SAK compared with patients with IV and the HCs (P < 0.01-0.05), but K10 expression was similar for the three groups (P > 0.05). Numbers of Ki-67+ and Melan-A+ cells were higher in patients with SAK than in patients with IV and the HCs (P < 0.05). CONCLUSIONS: These results demonstrate that excessive keratinocyte proliferation and abnormal differentiation contribute to epidermal hyperplasia, while melanocytic proliferation is responsible for the pigmented lesions in SAK.


Assuntos
Diferenciação Celular , Proliferação de Células , Células Epidérmicas , Queratinócitos/citologia , Queratinas/metabolismo , Ceratose/patologia , Melanócitos/citologia , Adolescente , Adulto , Epiderme/metabolismo , Feminino , Proteínas Filagrinas , Humanos , Imuno-Histoquímica , Proteínas de Filamentos Intermediários/metabolismo , Queratinócitos/metabolismo , Ceratose/metabolismo , Antígeno Ki-67/metabolismo , Masculino , Precursores de Proteínas/metabolismo , Pele/metabolismo , Pele/patologia , Regulação para Cima , Adulto Jovem
7.
Herz ; 42(6): 573-584, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27830272

RESUMO

BACKGROUND: Once hypertension is established, increased mechanical stretch stress becomes a leading cause of vascular remodeling. Clinical antihypertension guidelines demonstrate that antihypertension drugs prevent vascular remodeling in hypertensive patients mainly by lowering blood pressure, suggesting an indirect way of reducing the effects of stretch stress (hypertension). Whether these drugs can directly block the effects of the stretch stress on vascular remodeling has not been reported to date. This study was designed to answer this question and explore the underlying mechanisms. METHODS: Cultured quiescent vascular smooth muscle cells (VSMCs) were stimulated by stretch stress after pretreatment with nifedipine and hydrochlorothiazide. The phosphorylation levels of extracellular signal-regulated kinases (ERKs), c­Jun NH2-terminal protein kinases (JNKs), and p38 mitogen-activated protein kinase (MAPK) in VSMCs were detected via Western blotting. The treated cells were stained using triple-labeled immunofluorescence with Ki67 antibody and a TUNEL kit in the presence of DAPI for the detection of proliferative, apoptotic, and resting cells. RESULTS: Compared with the negative control, both nifedipine and hydrochlorothiazide had no influence on the phosphorylation of MAPKs and on the proliferation and apoptosis of VSMCs in resting state. Stretch stress could significantly induce increased phosphorylation of MAPKs as well as proliferation and apoptosis of VSMCs. Nifedipine inhibited the effects of stretch stress in a dose-dependent manner. Contrary to the effects of nifedipine, hydrochlorothiazide synergistically amplified the effects induced by stretch stress. CONCLUSION: Nifedipine and hydrochlorothiazide have opposing functions in the increased phosphorylation of MAPK and in the proliferation and apoptosis of VSMCs induced by stretch stress. The former plays a role as an inhibitor, while the latter functions as a promoter.


Assuntos
Apoptose/efeitos dos fármacos , Hidroclorotiazida/farmacologia , Hipertensão/tratamento farmacológico , Hipertensão/fisiopatologia , Músculo Liso Vascular/efeitos dos fármacos , Nifedipino/farmacologia , Remodelação Vascular/efeitos dos fármacos , Apoptose/fisiologia , Western Blotting , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/fisiologia , Células Cultivadas , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Imunofluorescência , Marcação In Situ das Extremidades Cortadas , Técnicas In Vitro , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Músculo Liso Vascular/fisiopatologia , Fosforilação , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismo
8.
Eur J Clin Nutr ; 70(7): 757-65, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-26908425

RESUMO

BACKGROUND/OBJECTIVES: Data regarding the relationships between body mass index (BMI) and brain tumors are inconsistent, especially for the commonly seen gliomas and meningiomas. Therefore, we conducted a dose-response meta-analysis to unravel the issue. SUBJECTS/METHODS: Cochrane Library, PubMed and Embase were searched for pertinent case-control and cohort studies updated to November 2014. Dose-response and quantitative analysis were conducted with random-effect model. RESULTS: Sixteen studies were included, containing 3 887 156 participants and 11 614 cases. In categorical analysis for the relationships between abnormal weight and BMI, the summary risk ratio (RR) of brain tumors was 1.34 (95% confidential interval (CI), 1.15-1.56) for obesity, 1.12 (95% CI, 1.05-1.19) for overweight and 0.77 (95% CI, 0.64-0.93) for underweight; the summary RR of gliomas was 1.13 (95% CI, 1.02-1.26) for overweight and 0.71 (95% CI, 0.58-0.88) for underweight; the summary RR of meningiomas was 1.48 (95% CI, 1.30-1.69) for obesity and 1.18 (95% CI, 1.07-1.31) for overweight. In dose-response analysis, for every 5 kg/m(2) increment of BMI, the summary RR was 1.13 (95% CI, 1.07-1.20) for overall brain tumors, 1.07 (95% CI, 0.97-1.19) for gliomas and 1.19 (95% CI, 1.14-1.25) for meningiomas. CONCLUSIONS: Excess weight was associated with increased risk of brain tumors and meningiomas but not with gliomas. Selective screening for brain tumors among obesity, especially for the females, might be more instructive.


Assuntos
Índice de Massa Corporal , Neoplasias Encefálicas/etiologia , Meningioma/etiologia , Obesidade/complicações , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Glioma/etiologia , Humanos , Masculino , Pessoa de Meia-Idade , Sobrepeso , Magreza , Adulto Jovem
9.
Rev Sci Instrum ; 85(11): 11D410, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25430173

RESUMO

Measurement and control of the current profile is essential for high performance and steady state operation of Experimental Advanced Superconducting Tokamak (EAST). For this purpose, a conventional Motional Stark Effect (MSE) diagnostics utilizing photoelastic modulators is proposed and investigated. The pilot experiment includes one channel to verify the feasibility of MSE, whose sightline intersects with Neutral Beam Injection at major radius of R = 2.12 m. A beam splitter is adopted for simultaneous measurements of Stark multiplets and their polarization directions. A simplified simulation code was also developed to explore the Stark splitting spectra. Finally, the filter is optimized based on the viewing geometry and neutral beam parameters.

10.
Biochem J ; 422(2): 343-52, 2009 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-19522704

RESUMO

Previously, we found that MRFs (myogenic regulatory factors) regulated the expression of PGC-1alpha (peroxisome-proliferator-activated receptor gamma co-activator 1alpha) by targeting a short region, from nt -49 to +2 adjacent to the transcription initiation site, that contained two E-boxes. However, only the E2-box had significant affinity for MRFs, and the E1-box was predicted to be the target of Bhlhe40 (basic helix-loop-helix family, member e40, also known as Stra13, Bhlhb2, DEC1 and Sharp2), a transcriptional repressor implicated in the regulation of several physiological processes. In the present study, by using EMSA (electrophoresis mobility-shift assay), we confirmed that Bhlhe40 targeted the E1-box and formed a complex with the basic helix-loop-helix transcription factor MyoD (myogenic differentiation factor D) on the PGC-1alpha core promoter. We demonstrate that Bhlhe40 binds to the promoters of PGC-1alpha and myogenic genes in vivo and that Bhlhe40 represses the MyoD-mediated transactivation of these promoters. Furthermore, we found that this repression could be relieved by P/CAF (p300/CBP-associated factor) in a dose-dependent manner, but not by CBP [CREB (cAMP-response-element-binding protein)-binding protein]. Bhlhe40 interacted with P/CAF and this interaction disrupted the interaction between P/CAF and MyoD. These results suggest that Bhlhe40 functions as a repressor of MyoD by binding to adjacent E-boxes and sequestering P/CAF from MyoD.


Assuntos
Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/fisiologia , Proteína MyoD/antagonistas & inibidores , Proteína MyoD/genética , Supressão Genética , Ativação Transcricional/fisiologia , Fatores de Transcrição de p300-CBP/fisiologia , Animais , Linhagem Celular , Camundongos , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo , Transativadores/antagonistas & inibidores , Transativadores/biossíntese , Transativadores/genética , Fatores de Transcrição
11.
J Nanosci Nanotechnol ; 8(9): 4353-9, 2008 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19049025

RESUMO

A direct route to silica-polypyrrole core-shell nanoparticles has been used to design new nanocomposites, in which the conducting part is then wrapped by an external silica shell in order to have finally neutral nanoparticles. The nanocomposites are characterized by TEM, spectroscopy, electrochemistry and thermal gravimetric analysis, demonstrating that the external silica shell actually insulates the conjugated polymer from the outer medium. Finally the electrorheological properties of these nanocomposites are checked in a dielectrophoretic device in which the motion of the particles induced by an external electric field can be used to monitor a switch of the light transmission properties.


Assuntos
Nanocompostos/química , Nanotecnologia/métodos , Reologia/métodos , Eletroquímica/métodos , Desenho de Equipamento , Microscopia Eletrônica de Transmissão , Conformação Molecular , Nanoestruturas/química , Polímeros/química , Pirróis/química , Dióxido de Silício/química , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria , Raios Ultravioleta
12.
Int Orthop ; 30(4): 257-61, 2006 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16565839

RESUMO

At present, no consensus exists on the best spacer alternative for the management of two-stage exchange arthroplasty of infected knee arthroplasties. In this retrospective study, patient records of 24 patients, who had undergone two-stage revisions in which resterilised prosthetic components were used as spacers, were reviewed. The outcome was compared to that of operations performed during the same period (1993-2003) using cement spacers (n=10). With an average follow-up of 32 months, control of infection was achieved in 26 cases (76%), with good or excellent clinical outcome in 19 cases (56%). Treatment failed and resulted in amputation at the level of the thigh before reimplantation in one case. Three patients did not undergo reimplantation. In four cases (12%) infection relapsed. The reinfection rate did not differ between the two spacer groups. Patients treated with resterilised components had a superior range of motion during the period between the two stages. Operative time was shorter and there was less blood loss in the reimplantation arthroplasty when a prosthetic spacer was used. We consider resterilised prosthetic components a safe and effective alternative to cement spacers in the management of infected knee arthroplasties.


Assuntos
Artroplastia do Joelho/métodos , Infecções Bacterianas/etiologia , Infecções Bacterianas/cirurgia , Cimentos Ósseos , Prótese do Joelho/efeitos adversos , Infecções Relacionadas à Prótese/etiologia , Infecções Relacionadas à Prótese/cirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Desenho de Prótese , Reoperação/métodos , Estudos Retrospectivos
13.
J Phys Chem B ; 110(5): 2080-3, 2006 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-16471786

RESUMO

We report the fabrication of a novel carbon structure consisting of uniform carbon nanotubes formed in the nanochannels of anodic aluminum oxide (AAO) templates, with the surface side open and connected by a uniform carbon sheet. The uniformity of the fabricated CNT arrays, plus the carbon film on the AAO surface interconnecting the open ends of all CNTs, constitute the major characteristics unique to our carbon structures. Some potential applications of such structures are noted.

14.
J Bone Joint Surg Br ; 87(9): 1222-4, 2005 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16129746

RESUMO

We report a consecutive series of 16 revision total knee arthroplasties using the Total Condylar III system in 14 patients with inflammatory arthritis which were performed between 1994 and 2000. There were 11 women and three men with a mean age of 59 years (36 to 78). The patients were followed up for 74 months (44 to 122). The mean pre-operative Knee Society score of 37 points (0 to 77) improved to 88 (61 to 100) at follow-up (t-test, p < 0.001) indicating very good overall results. The mean range of flexion improved from 62 degrees (0 degrees to 120 degrees) to 98 degrees (0 degrees to 145 degrees) (t-test, p < 0.05) allowing the patients to stand from a sitting position. The mean Knee Society pain score improved from 22 (10 to 45) to 44 (20 to 50) (t-test, p < 0.05). No knee had definite loosening, although five showed asymptomatic radiolucent lines. Complications were seen in three cases, comprising patellar pain, patellar fracture and infection. These results suggest that the Total Condylar III system can be used successfully in revision total knee arthroplasty in inflammatory arthritis.


Assuntos
Artrite Reumatoide/cirurgia , Artroplastia do Joelho/métodos , Prótese do Joelho , Adulto , Idoso , Artrite Reumatoide/fisiopatologia , Feminino , Seguimentos , Humanos , Articulação do Joelho/fisiopatologia , Masculino , Pessoa de Meia-Idade , Complicações Pós-Operatórias , Falha de Prótese , Amplitude de Movimento Articular , Reoperação/métodos , Método Simples-Cego , Resultado do Tratamento
15.
Phys Rev E Stat Nonlin Soft Matter Phys ; 67(1 Pt 2): 016612, 2003 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-12636630

RESUMO

We present a detailed study of the effect of planar stacking disorder on optical properties of inverted opal photonic crystals. Systems with periodic stacking sequences are first studied that include face centered cubic, hexagonal close-packed, and doubly hexagonal close-packed photonic crystals. For the structures with periodic stacking order, we evaluate the band structure followed by calculation of transmission spectrum along the direction perpendicular to the hexagonal close-packing plane of the structures. Inverted opal photonic crystals with random stacking sequences are then studied by calculating average transmittance of the photonic crystal slabs over various random stacking configurations. The position and width of the lowest stop gap along the direction normal to the hexagonal close-packing plane is found to be invariant, regardless of the stacking sequence in the photonic crystal. We show how the propagation properties at higher frequencies are affected by the stacking configurations (both periodic and disordered stacking sequences), particularly those near the edges of the absolute band gap. The obtained results are directly relevant to transmission/reflection experiments on inverted opal photonic crystals with complete band gap.

16.
Phys Rev Lett ; 90(8): 083901, 2003 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-12633427

RESUMO

Layered heterostructures combining ordinary and negative refractive index materials are shown to display a new type of photonic band gap corresponding to zero (volume) averaged refractive index. Distinct from band gaps induced by Bragg scattering, the zero-n; gap is invariant upon a change of scale length and is insensitive to disorder that is symmetric in the random variable. A metallic structure that exhibits such a band gap is explicitly designed, and its properties are calculated with accurate finite difference time domain simulations.

17.
Chang Gung Med J ; 24(8): 492-501, 2001 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-11601191

RESUMO

BACKGROUND: To study the differences in the health status of rural and urban ambulatory elderly in Taipei County. METHOD: Non-compulsory general health check-up for elderly people over 65 years old in rural and urban areas. The content of the health examination included past medical history, health behavior, physical examination, laboratory examination, electrocardiogram and x-ray. Chi square test, t-test and logistic regression were applied for analysis. Risk factors relating to the cardiovascular system were included in the study. Gender differences affecting the prevalence of diseases and health behavior were also considered in the analysis. RESULTS: Significantly higher proportions of the rural elderly men smoked, drank alcohol, and had hypertension and impaired renal function. On the other hand, higher proportions of rural elderly women were obese and had diabetes, hypertension and renal impairment. The mean plasma glucose level of newly-diagnosed diabetic patients in the rural area was significantly higher than that in the urban area (p < 0.05). Diabetes, obesity, hypercholesterolemia and smoking were significantly associated with hypertension. The odds ratio for hypertension between rural and urban areas was 1.45 (p < 0.0001). The cardiovascular risk-rating score of rural elderly was statistically higher than that of urban elderly (p < 0.001). CONCLUSION: There were some minor differences in health status between urban and rural elderly. Health promotion should be varied according to the needs of various communities and various risk groups. Further studies should concentrate on prospective cohort research with well-defined determinants to evaluate whether cost-effective biopsychosocial intervention is necessary.


Assuntos
Nível de Saúde , Idoso , Consumo de Bebidas Alcoólicas , Feminino , Humanos , Hipertensão/epidemiologia , Masculino , Saúde da População Rural , Fumar , Taiwan , Saúde da População Urbana
18.
Science ; 292(5526): 2462-5, 2001 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-11431560

RESUMO

Investigation of the magnetic and transport properties of single-walled small-diameter carbon nanotubes embedded in a zeolite matrix revealed that at temperatures below 20 kelvin, 4 angstrom tubes exhibit superconducting behavior manifest as an anisotropic Meissner effect, with a superconducting gap and fluctuation supercurrent. The measured superconducting characteristics display smooth temperature variations owing to one-dimensional fluctuations, with a mean-field superconducting transition temperature of 15 kelvin. Statistical mechanic calculations based on the Ginzburg-Landau free-energy functional yield predictions that are in excellent agreement with the experiments.

19.
Phys Rev Lett ; 86(24): 5562-5, 2001 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-11415301

RESUMO

Nearly 3 orders of magnitude enhancement in the Hall coefficient is observed in Cu(x)-(SiO(2))(1--x) granular films. This large enhancement of the Hall coefficient not only is significantly larger than the prediction of the classical percolation theory, but also occurs at a metal concentration identified to be the quantum percolation threshold. Measurements of the electron dephasing length and magnetoresistance, plus the TEM characterization of microstructures, yield a physical picture consistent with the mechanism of the local quantum interference effect.

20.
Opt Express ; 8(3): 203-8, 2001 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-19417805

RESUMO

The vector wave multiple scattering method is a reliable and efficient technique in treating the photonic band gap problem for photonic crystals composed of spherically scattering objects with metallic components. In this paper, we describe the formalism and its application to the photonic band structures of systems comprising of metallo-dielectric spheres. We show that the photonic band gaps are essentially determined by local short-range order rather than by the translational symmetry if the volume fraction of the metallic core is high.

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