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Group medical visits for osteoporosis can improve access to care while being highly accepted by patients. In this study, a similar proportion of women planned to initiate pharmacotherapy after attending a group or traditional one-on-one osteoporosis consultation, indicating that the group consultation model does not produce unexpected treatment decisions. INTRODUCTION: Group medical consultations for osteoporosis are time-efficient and highly accepted by patients, but effects on treatment decisions are unknown. We aimed to compare women's decisions to initiate or decline osteoporosis pharmacotherapy after attending either a group or transitional one-on-one osteoporosis consultation. METHODS: In this observational study, we prospectively evaluated postmenopausal women referred to an osteoporosis clinic who attended a group medical visit and compared their decisions regarding pharmacologic osteoporosis treatment with retrospective data from a cohort of women who attended a traditional consultation. Both consultation types involved interaction with a specialist physician, individualized fracture risk estimation (using FRAX®), and education regarding fracture consequences and available osteoporosis medications. Both forms of consultation emphasized shared decision-making; however, group consultation attendees did not receive personalized treatment recommendations from the physician. RESULTS: We reviewed the records of 125 women (median age 63 years) who attended a group consultation and 83 women (median age 64 years) who attended a traditional consultation between 2016 and 2019. Twenty-four (19%) of the group cohort and 16 (19%) of the traditional cohort were at high 10-year risk of major osteoporotic fracture (FRAX® ≥ 20.0%). A similar proportion planned to initiate pharmacologic therapy after the group and traditional consultations (23% vs 16%, p = 0.22); these proportions were comparable among women at high risk (42% vs 50%, p = 0.75) and moderate risk (19% vs 15%, p = 0.77), but a higher proportion of low-risk women planned to initiate therapy after the group consultation (18% vs 0%, p = 0.009). CONCLUSION: Patient decisions to initiate pharmacologic treatment made during a group visit are similar to those made during traditional one-on-one consultation. The group consultation model represents an alternative to one-on-one assessment for delivering osteoporosis consultative services.
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Osteoporosis Posmenopáusica , Osteoporosis , Fracturas Osteoporóticas , Densidad Ósea , Estudios de Cohortes , Femenino , Humanos , Masculino , Persona de Mediana Edad , Osteoporosis/tratamiento farmacológico , Osteoporosis/epidemiología , Osteoporosis Posmenopáusica/tratamiento farmacológico , Fracturas Osteoporóticas/epidemiología , Fracturas Osteoporóticas/etiología , Fracturas Osteoporóticas/prevención & control , Posmenopausia , Derivación y Consulta , Estudios Retrospectivos , Medición de Riesgo , Factores de RiesgoRESUMEN
This study is to estimate the lifetime risks of hip fracture in Chinese patients with type 2 diabetes. INTRODUCTION: The lifetime risks of hip fracture have not been reported across the age spectrum in male adults and female adults with type 2 diabetes. METHODS: A retrospective cohort study was conducted on 25275 men and 27953 women with type 2 diabetes aged 30-100 years old and participated in the National Diabetes Case Management Program in 2002-2004 in Taiwan. Sociodemographic factors, biomarkers, and comorbidity at the baseline and hip fracture events were analyzed with Cox proportional hazards regression models with age as the time scale. RESULTS: Significant differences in the lifetime risks of hip fracture were observed between men and women with type 2 diabetes. The cumulative lifetime incidences (%) of hip fracture at 50, 60, 65, 70, 75, 80, and 85 years old for men were 0.11, 0.40, 0.84, 1.84, 3.82, 8.53, and 16.72, respectively. The corresponding lifetime incidences (%) for women at 50, 60, 65, 70, 75, 80, and 85 years old were 0.05, 0.50, 1.36, 3.89, 9.56, 21.19, and 35.45, respectively. With competing risks, the significant multivariate-adjusted hazard ratio of developing hip fracture included smoking, alcohol drinking, duration of diabetes, type of oral hypoglycemic drugs use (no medication, sulfonylurea only, thiazolidinediones (TZD) only or TZD plus others, other single or multiple oral agents, insulin use, insulin plus oral hypoglycemic drug use), loop diuretics use, use of corticosteroids, normal weight or underweight, hyperlipidemia, and chronic obstructive pulmonary disease. CONCLUSIONS: The gender differences in lifetime hip fracture risk were significant. Thiazolidinediones and insulin use are factors with the greater magnitude of strength of association among those significantly associated with hip fracture.
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Diabetes Mellitus Tipo 2 , Fracturas de Cadera , Tiazolidinedionas , Adulto , Anciano , Anciano de 80 o más Años , Diabetes Mellitus Tipo 2/complicaciones , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Diabetes Mellitus Tipo 2/epidemiología , Femenino , Fracturas de Cadera/epidemiología , Fracturas de Cadera/etiología , Humanos , Hipoglucemiantes/uso terapéutico , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Factores de Riesgo , Taiwán/epidemiología , Tiazolidinedionas/uso terapéuticoRESUMEN
The interplay between hydrogen and nanovoids, despite long being recognized as a central factor in hydrogen-induced damage in structural materials, remains poorly understood. Here, focusing on tungsten as a model body-centred cubic system, we explicitly demonstrate sequential adsorption of hydrogen adatoms on Wigner-Seitz squares of nanovoids with distinct energy levels. Interaction between hydrogen adatoms on nanovoid surfaces is shown to be dominated by pairwise power-law repulsion. We establish a predictive model for quantitative determination of the configurations and energetics of hydrogen adatoms in nanovoids. This model, combined with the equation of states of hydrogen gas, enables the prediction of hydrogen molecule formation in nanovoids. Multiscale simulations, performed based on our model, show good agreement with recent thermal desorption experiments. This work clarifies fundamental physics and provides a full-scale predictive model for hydrogen trapping and bubbling in nanovoids, offering long-sought mechanistic insights that are crucial for understanding hydrogen-induced damage in structural materials.
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We investigated the association between blood pressure variability measured by the coefficient of variation (CV) of blood pressure and hip fracture in older persons with diabetes. After excluding patients with acute complications and comorbidities, a positive association with similar magnitude of strength was found between BP variability and hip fracture, compared with that in the original analysis. INTRODUCTION: Hypertension is a risk factor of osteoporosis and hip fracture, but studies have yet to investigate whether blood pressure variability measured by the CV of blood pressure can predict hip fracture in older persons with diabetes. METHODS: We conducted a retrospective cohort study on 21,160 patients who suffered from type 2 diabetes (age ≥ 50 years) and participated in the National Diabetes Care Management Program in Taiwan. The patients' 1-year variability in systolic blood pressure (SBP) and diastolic blood pressure (DBP) at the baseline and subsequent hip fracture incidence for 8.2 years were analyzed. RESULTS: There were 937 recorded incident hip fractures. SBP-CV and DBP-CV were classified based on their tertiles. After multivariate adjustment was conducted, SBP-CV found to be a predictor of hip fracture, and its hazard ratio was 1.18 (95% CI 1.00-1.40) for the third tertile compared with the first tertile. CONCLUSIONS: Our study suggests SBP stability is a predictor for hip fracture incidence in older persons with type 2 diabetes.
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Presión Sanguínea/fisiología , Diabetes Mellitus Tipo 2/complicaciones , Fracturas de Cadera/etiología , Fracturas Osteoporóticas/etiología , Anciano , Diabetes Mellitus Tipo 2/epidemiología , Femenino , Fracturas de Cadera/epidemiología , Fracturas de Cadera/fisiopatología , Humanos , Hipertensión/complicaciones , Hipertensión/epidemiología , Hipertensión/fisiopatología , Masculino , Persona de Mediana Edad , Fracturas Osteoporóticas/epidemiología , Fracturas Osteoporóticas/fisiopatología , Estudios Retrospectivos , Medición de Riesgo/métodos , Factores de Riesgo , Taiwán/epidemiologíaRESUMEN
BACKGROUND AND PURPOSE: No study has established a prediction dementia model in the Asian populations. This study aimed to develop a prediction model for dementia in Chinese type 2 diabetes patients. METHODS: The retrospective cohort study included 27 540 Chinese type 2 diabetes patients (aged 50-94 years) enrolled in the Taiwan National Diabetes Care Management Program. Participants were randomly allocated into derivation and validation sets at a 2:1 ratio. Cox proportional hazards regression models were used to identify risk factors for dementia in the derivation set. Steps proposed by the Framingham Heart Study were used to establish a prediction model with a scoring system. RESULTS: The average follow-up was 8.09 years, with a total of 853 incident dementia cases in the derivation set. The dementia risk score summed up the individual scores (from 0 to 20). The areas under the curve of 3-, 5- and 10-year dementia risks were 0.82, 0.79 and 0.76 in the derivation set and 0.84, 0.80 and 0.75 in the validation set, respectively. CONCLUSIONS: The proposed score system is the first dementia risk prediction model for Chinese type 2 diabetes patients in Taiwan.
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Demencia/etiología , Diabetes Mellitus Tipo 2/complicaciones , Anciano , Anciano de 80 o más Años , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Medición de Riesgo , Factores de RiesgoRESUMEN
OBJECTIVE: To conduct a systematic review and meta-analysis of studies that measured cytokine and chemokine levels in individuals with major depressive disorder (MDD) compared to healthy controls (HCs). METHOD: The PubMed/MEDLINE, EMBASE, and PsycINFO databases were searched up until May 30, 2016. Effect sizes were estimated with random-effects models. RESULT: Eighty-two studies comprising 3212 participants with MDD and 2798 HCs met inclusion criteria. Peripheral levels of interleukin-6 (IL-6), tumor necrosis factor (TNF)-alpha, IL-10, the soluble IL-2 receptor, C-C chemokine ligand 2, IL-13, IL-18, IL-12, the IL-1 receptor antagonist, and the soluble TNF receptor 2 were elevated in patients with MDD compared to HCs, whereas interferon-gamma levels were lower in MDD (Hedge's g = -0.477, P = 0.043). Levels of IL-1ß, IL-2, IL-4, IL-8, the soluble IL-6 receptor (sIL-6R), IL-5, CCL-3, IL-17, and transforming growth factor-beta 1 were not significantly altered in individuals with MDD compared to HCs. Heterogeneity was large (I2 : 51.6-97.7%), and sources of heterogeneity were explored (e.g., age, smoking status, and body mass index). CONCLUSION: Our results further characterize a cytokine/chemokine profile associated with MDD. Future studies are warranted to further elucidate sources of heterogeneity, as well as biosignature cytokines secreted by other immune cells.
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Quimiocinas/metabolismo , Citocinas/metabolismo , Trastorno Depresivo Mayor/inmunología , Femenino , Humanos , MasculinoRESUMEN
We investigated the association between fasting plasma glucose variability (FPG-CV) and the risk of hip fracture in elderly diabetic patients. Our finding showed a temporal association between FPG-CV and hip fracture as patients categorized as FPG-CV greater than 25.4 % showed an increased risk in hip fractures. INTRODUCTION: Hip fracture is a major health burden in the population and is associated with high rates of mortality and morbidity especially in elderly. It is evident that diabetes mellitus is a risk factor of osteoporosis which is a significant risk factor of hip fracture. However, epidemiological studies exploring the risks of hip fracture among type 2 diabetic patients are limited. METHODS: A retrospective study of 26,501 ethnic Chinese older persons enrolled in the National Diabetes Care Management program in Taiwan was conducted; related factors were analyzed with extended Cox proportional hazards regression models to competing risk data on hip fracture incidence. RESULTS: The results show a temporal association between FPG-CV and hip fracture as patients categorized as FPG-CV greater than 25.4 % showed an increased risk in hip fractures, confirming a linear relationship between the two. After multivariate adjustment, the risk of hip fracture increased among patients with FPG-CV of 25.4-42.3 % and >42.3 % compared with patients with FPG-CV of ⦠14.3 % (hazard ratio, 1.35; 95 % confidence interval 1.14-1.60 and 1.27; 1.07-1.52, respectively). Significant linear trends among various FPG-CV were observed. CONCLUSIONS: Thus, the present study demonstrated the importance of glucose stability for fracture prevention in older persons with type 2 diabetes. Future studies should be conducted to explore whether reduction in glucose oscillation in older adults with diabetes mellitus can reduce the risk of hip fracture.
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Glucemia/análisis , Diabetes Mellitus Tipo 2/complicaciones , Fracturas de Cadera/sangre , Anciano , Diabetes Mellitus Tipo 2/sangre , Ayuno , Femenino , Fracturas de Cadera/complicaciones , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Factores de Riesgo , TaiwánRESUMEN
Surveillance data on the burden of pertussis in Asian adults are limited. This cross-sectional study evaluated the prevalence of serologically confirmed pertussis in adults with prolonged cough in Malaysia, Taiwan and Thailand. Adults (⩾19 years) with cough lasting for ⩾14 days without other known underlying cause were enrolled from outpatient clinics of seven public and/or private hospitals. Single blood samples for anti-pertussis toxin antibodies (anti-PT IgG) were analysed and economic impact and health-related quality of life (EQ-5D) questionnaires assessed. Sixteen (5·13%) of the 312 chronically coughing adults had serological evidence of pertussis infection within the previous 12 months (anti-PT IgG titre ⩾62·5 IU/ml). Three of them were teachers. Longer duration of cough, paroxysms (75% seroconfirmed, 48% non-seroconfirmed) and breathlessness/chest pain (63% seroconfirmed, 36% non-seroconfirmed) were associated with pertussis (P < 0·04). Of the seroconfirmed patients, the median total direct medical cost per pertussis episode in public hospitals (including physician consultations and/or emergency room visits) was US$13 in Malaysia, US$83 in Taiwan (n = 1) and US$26 in Thailand. The overall median EQ-5D index score of cases was 0·72 (range 0·42-1·00). Pertussis should be considered in the aetiology of adults with a prolonged or paroxysmal cough, and vaccination programmes considered.
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Anticuerpos Antibacterianos/sangre , Toxina del Pertussis/inmunología , Tos Ferina/sangre , Tos Ferina/epidemiología , Adulto , Bordetella pertussis/inmunología , Estudios Transversales , Femenino , Humanos , Malasia/epidemiología , Masculino , Persona de Mediana Edad , Prevalencia , Estudios Seroepidemiológicos , Taiwán/epidemiología , Tailandia/epidemiología , Adulto JovenRESUMEN
This study detected the distribution of laminin during embryonic formation by immunofluorescence. To determine the possible function of laminin on developmental ability of in vitro fertilized embryos, the presumptive zygotes were divided and transferred to CR1aa medium supplemented with different concentrations (0 µg/ml, 5 µg/ml, 10 µg/ml and 20 µg/ml) of laminin. To explore the association with sperm-oocyte fusion, oocytes and/or sperm were pre-incubated with laminin or anti-ß1 antibody before insemination. Laminin was absent in mature oocytes and could be detected first at the 8-cell stage and then displayed an increasing tendency. Adding 10 µg/ml laminin to the culture medium improved embryonic development including cleavage rate, blastocyst rate, total cell numbers in the blastocyst and cell numbers in the inner cell mass. Laminin inhibited sperm-oocyte fusion when incubated with oocytes and/or sperm before in vitro fertilization, and only integrin-ß1 of sperm was involved in sperm-oocyte binding. Inhibition may be caused by blocking ß1, but why laminin inhibits fertilization is still unknown. The results suggest that laminin plays an important role during embryonic formation and has a negative function in sperm-oocyte fusion, but improves embryonic development. However, only integrin-ß1 is involved in sperm-oocyte binding.
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Bovinos/fisiología , Desarrollo Embrionario/efectos de los fármacos , Fertilización In Vitro/veterinaria , Integrina beta1/metabolismo , Laminina/farmacología , Interacciones Espermatozoide-Óvulo/fisiología , Animales , Anticuerpos , Blastocisto/efectos de los fármacos , Bovinos/embriología , Medios de Cultivo , Técnicas de Cultivo de Embriones , Femenino , Fibrinolíticos/farmacología , Regulación del Desarrollo de la Expresión Génica , Heparina/farmacología , Laminina/metabolismo , Masculino , Oocitos/efectos de los fármacos , Oocitos/fisiología , Espermatozoides/efectos de los fármacos , Espermatozoides/fisiologíaRESUMEN
In accelerator driven systems (ADSs), steels will suffer not only from the irradiation damage produced by protons or neutrons, but also from the dissolution corrosion induced by the liquid lead-bismuth eutectic (LBE). In this work we investigate the interactions between LBE atoms (Pb, Bi) and the irradiation induced defects X (X is helium, vacancy or divacancy) in α-Fe based on first-principles calculations. It is found that LBE atoms repulse each other without irradiation defects, while they aggregate easily with the defects to form X-Pbn and X-Bin complexes. This indicates that the irradiation defects could promote the aggregation of LBE atoms in iron, especially Bi atoms. The total binding energies of the X-Pbn and X-Bin complexes increase with the number of Pb and Bi atoms, respectively. The origin of the total binding energies of the complexes is further discussed via the electronic structures and the distortion of the crystalline lattice. Finally, the concentration evolutions of the Vac-(Bi)n complexes and unbound vacancies with temperature are predicted by the mass action analysis. This work provides important information for the synergistic effect of irradiation and LBE corrosion on the steels in the ADSs, which can be used as basic parameters for further study.
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OBJECTIVES: To examine the prognostic influence of hyoid bone invasion in advanced base of tongue squamous cell carcinoma treated with chemoradiation. METHODS: We retrospectively reviewed pre-treatment imaging (CT/MRI) for the presence or absence of hyoid bone invasion in patients with advanced (clinical T3 or T4a stage) base of tongue squamous cell carcinoma treated with chemoradiation from January 2001 to January 2011. We compared patients with hyoid bone invasion to those without based on the following metrics: 1-, 2- and 5-year locoregional recurrence-free survival, disease-free survival, disease-specific survival and overall survival. RESULTS: Eleven of thirty-seven patients had hyoid invasion present on pre-treatment imaging. Average follow-up was 45 months. Patients with hyoid bone invasion were found to have lower percentages in all survival metrics measured compared to patients without, respectively, with statistical significance achieved in the following: 2-year locoregional recurrence-free survival: 36.4% versus 86.4% (P = 0.006), 5-year locoregional recurrence-free survival: 12.5% versus 63.6% (P = 0.05), 2-year disease-free survival: 36.4% versus 77.3% (P = 0.05), 5-year disease-free survival: 12.5% versus 63.3% (P = 0.05) and the Kaplan-Meier curve for locoregional recurrence-free survival (P = 0.0075). CONCLUSIONS: Hyoid bone invasion by base of tongue squamous cell carcinoma may indicate a poorer prognosis despite treatment. Hyoid bone invasion may be a possible indication for intensification of treatment and/or may indicate a necessity for increasing the degree of post-treatment surveillance monitoring and imaging.
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Carcinoma de Células Escamosas/patología , Carcinoma de Células Escamosas/terapia , Hueso Hioides/patología , Estadificación de Neoplasias , Neoplasias de la Lengua/patología , Neoplasias de la Lengua/terapia , California/epidemiología , Carcinoma de Células Escamosas/mortalidad , Quimioradioterapia , Supervivencia sin Enfermedad , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Invasividad Neoplásica , Pronóstico , Estudios Retrospectivos , Tasa de Supervivencia/tendencias , Factores de Tiempo , Neoplasias de la Lengua/mortalidadRESUMEN
Runoff in major rivers in China has been decreasing in recent decades, mainly due to climate change and human activity. River basin managers have a critical interest in detecting and diagnosing non-stationaries in runoff time series. Here we use a rainfall runoff model-based approach to identify the human-disturbed periods of the record. The method is applied to the Kuye River catchment, located in the Loess Plateau, China. The SimHyd model performs well for simulation of monthly natural discharges, and the method suggests that discernable human influence began in 1980. Anthropogenic effects were detectable several years earlier at the downstream stations than the upstream stations, consistent with pace and timing of soil and water conservation measures implemented across the Kuye River catchment.
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Hidrología/métodos , Modelos Teóricos , China , Cambio Climático , Simulación por Computador , Actividades Humanas , Humanos , Lluvia , Ríos , Suelo , Abastecimiento de AguaRESUMEN
BACKGROUND: Type 2 diabetes mellitus, gastric and hepatobiliary comorbidities, and cancer share common risk factors: for example, tobacco, obesity, physical inactivity, high calorie intake, and metabolic disorders. Prior studies find type 2 diabetes and gastric and hepatobiliary comorbidities heightening risk of pancreatic cancer. Yet joint association of type 2 diabetes mellitus and gastric and hepatobiliary comorbidities on pancreatic cancer risk has not been assessed. METHODS: This study rates independent/joint effects of type 2 diabetes as well as gastric and hepatobiliary comorbidity on pancreatic cancer risk for a retrospective population-based cohort of 166,850 type 2 diabetics identified in 1997-1998 and followed for 10-11 years, comparing their cancer incidence with that of 166,850 non-diabetics matched for age, gender, and locale. Time-dependent Cox's proportional hazards model evaluted joint association of type 2 diabetes and chronic conditions on pancreatic cancer risk. RESULTS: A total of 1178 subjects were newly diagnosed with pancreatic cancer during follow-up, with incidence rates of 0.49 per 1000 person-years in type 2 diabetes and 0.26 per 1000 person-years in the non-diabetics. We observed greater magnitude of hazard ratios (HRs) of pancreatic cancer for patients with type 2 diabetes along with acute alcoholic hepatitis, acute pancreatitis, cholecystitis, and gastric ulcer compared with patients without type 2 diabetes or counterpart comorbidity (HR: 1.36, 95% confidence interval (CI): 1.19-1.56; 1.74, 1.23-2.45; 9.18, 7.44-11.33; and 2.31, 1.98-2.70, respectively). Main effects of type 2 diabetes were all statistically with narrow 95% CI and remained similar across risk stratification with various comorbidities: range 1.59-1.80. CONCLUSIONS: Our study demonstrates that pre-existing type 2 diabetes, acute alcoholic hepatitis, acute pancreatitis, cholecystitis, and gastric ulcer independently or jointly predict subsequent pancreatic cancer risk. Clinicians must recognise burden of these gastric and hepatobiliary comorbidities and keep clinically vigilant for their diagnosis.
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Diabetes Mellitus Tipo 2/complicaciones , Hepatopatías/complicaciones , Neoplasias Pancreáticas/etiología , Gastropatías/complicaciones , Adulto , Anciano , Estudios de Cohortes , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Pancreatitis/complicaciones , Modelos de Riesgos Proporcionales , RiesgoRESUMEN
UNLABELLED: We studied 472 elders to assess joint association of vitamin D receptor (VDR) variability and physical activity on low handgrip strength (LHS) and osteoporosis (OST). Our findings showed that higher risks of OST were associated with physically inactive elders with some specific VDR variations, highlighting the importance of promotion program for physical activity. INTRODUCTION: The aim of this study was to determine the joint association between VDR variability and physical activity on LHS and OST in community-dwelling elders. METHODS: Bone mineral density of the lumbar spine (LS), the femoral neck (FN), and the total hip were measured by dual-energy X-ray absorptiometry. Four single-nucleotide polymorphisms (SNPs) (rs7975232, rs1544410, rs2239185, and rs3782905) of the VDR gene were examined in 472 participants. RESULTS: Physical inactivity and each of the four SNPs were jointly associated with a significantly greater risk of LHS in people than that associated with each of the VDR SNPs or low physical activity alone. Physically inactive men with the AG or AA genotype of rs2239185 had a significantly greater risk of overall, LS, and FN OST than those of physically active men with the GG genotype [odds ratio (OR) 3.57, 95 % confidence interval (CI) 1.10-11.65; OR 4.74, 95 % CI 1.43-15.70; and OR 5.06, 95 % CI 1.08-23.71, respectively]. Similarly, physically inactive women with the CG or CC genotype of rs3782905 and the AG or AA genotype of rs1544410 had a significantly greater risk of FN OST than physically active women with the GG genotype (OR 5.33, 95 % CI 1.23-23.06 and OR 5.36, 95 % CI 1.11-25.94, respectively). CONCLUSIONS: VDR polymorphisms and physical activity are jointly associated with LHS and OST in elders. Health care programs should promote physical activity among elders as a cost-effective way to prevent LHS and OST, especially in those who may be genetically predisposed.
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Fuerza de la Mano/fisiología , Actividad Motora/fisiología , Osteoporosis/genética , Receptores de Calcitriol/genética , Absorciometría de Fotón , Anciano , Anciano de 80 o más Años , Densidad Ósea/fisiología , Femenino , Cuello Femoral/fisiopatología , Frecuencia de los Genes , Predisposición Genética a la Enfermedad , Genotipo , Articulación de la Cadera/fisiopatología , Humanos , Vértebras Lumbares/fisiopatología , Masculino , Osteoporosis/fisiopatología , Polimorfismo de Nucleótido SimpleRESUMEN
The nature of the liquid-glass transition remains an unsolved fundamental problem. One aspect is the striking change in dynamics of the structural α-relaxation generally observed at a temperature T(B) above Tg in all glass-formers. More intriguing in the case of polymers is that the change of dynamics occurs not only in the structural α-relaxation but also in the sub-Rouse modes, i.e. chain modes in between the α-relaxation and the Rouse modes. However, the nature of the dynamic crossover of the sub-Rouse modes remains unclear. In this paper, the dynamics of a series of poly(n-alkyl methacrylates) with different molecular weights and microstructures studied by mechanical spectroscopy are reported. We demonstrate that the sub-Rouse modes exhibit a similar crossover of dynamics at the same T(B) as the α-relaxation. This property shared by the two viscoelastic mechanisms is remarkable. By invoking the results from the studies using positron annihilation spectroscopy and adiabatic calorimetry, we show that both viscoelastic mechanisms are coupled to density, correlated with the change of the configuration entropy, and are intermolecularly cooperative. The time scale of sub-Rouse modes at T(B) of the polymers studied is approximately independent of molecular weight and micro-structure of the polymers studied. The findings enhance the understanding of the sub-Rouse modes and their manifestation in the viscoelasticity of polymers in the glass-rubber transition region.
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The grain contact force, the key player in determining the mechanical properties of grain materials, depends on the elastic modulus and deformation (δ) of grains. However, our knowledge on their relationship in a three-dimensional granular medium is limited mainly owing to the difficulty of realizing direct experimental investigation. Using a simple force vibration technique, we measure the dissipation spectra (the frequency response) of three kinds of grains with different elastic moduli under different pressures (to change the grain deformation). The dissipation spectra exhibit multiple resonant peaks, indicative of the resonance of grain chains with different lengths. This allows us to quantitatively characterize the elastic behaviors of grain chains. A universal correlation of the resonant frequency (f) of a grain chain with deformation is observed for all granular systems with different material properties (Young's modulus E, density ρ and Poisson's coefficient ν): f(2) â δ(1/2)E/ρ(1 - ν). The deformation of the grain chain under pressure follows a p(2/3) pressure dependence. This general behavior suggests that the pressure-induced deformation of the grain chain under low-frequency weak shear vibration is overwhelmed by the nonlinear Hertzian contact elasticity.
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A contaminated hospital environment has been identified as an important reservoir of pathogens causing healthcare-associated infections. This study is to evaluate the efficacy of bacteria killing nanotechnology Bio-Kil on reducing bacterial counts in an intensive care unit (ICU). Two single-bed rooms (S-19 and S-20) in the ICU were selected from 7 April to 27 May 2011. Ten sets of new textiles (pillow cases, bed sheets, duvet cover, and patient clothing) used by patients in the two single-bed rooms were provided by the sponsors. In the room S-20, the 10 sets of new textiles were washed with Bio-Kil; the room walls, ceiling, and air-conditioning filters were treated with Bio-Kil; and the surfaces of instruments (respirator, telephone, and computer) were covered with Bio-Kil-embedded silicon pads. Room S-19 served as the control. We compared the bacterial count on textiles and environment surfaces as well as air samples between the two rooms. A total of 1,364 samples from 22 different sites in each room were collected. The mean bacterial count on textiles and environmental surfaces in room S-20 was significantly lower than that in room S-19 (10.4 vs 49.6 colony-forming units [CFU]/100 cm(2); P < 0.001). Room S-20 had lower bacterial counts in air samples than room S-19 (33.4-37.6 vs 21.6-25.7 CFU/hour/plate; P < 0.001). The density of microbial isolations was significantly greater among patients admitted to room S-19 than those to room S-20 (9.15 vs 5.88 isolates per 100 patient-days, P < 0.05). Bio-Kil can significantly reduce bacterial burden in the environment of the ICU.
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Control de Infecciones/métodos , Unidades de Cuidados Intensivos , Nanotecnología/métodos , Esterilización/métodos , Recuento de Colonia Microbiana , Humanos , Esterilización/instrumentaciónRESUMEN
Using first principles calculations, dissolution corrosion of liquid metals on iron surfaces has been investigated by calculating adsorption energies of metal atoms in the liquid phase on the surface and escape energies of surface Fe atoms. The adsorption energies, characterizing the stability of the adsorbed atoms on the investigated surfaces, show that Bi is more stable than Pb and Au. The escape energies, representing the energy required for an Fe atom to escape from the surface, show that adsorbed Pb makes surface Fe atoms escape more easily than Bi and Au. The combination of adsorption energy and escape energy indicates that the corrosion capabilities of liquid metals decrease in the order Bi > Pb > Au. This is further proved by the investigation of surface properties, such as inter-layer distance, magnetic momentum and charge density difference. The results are consistent with experimental results that Fe can be corroded more severely in Bi than in Pb. In the case of liquid alloys, chemical proportions of compositions are incorporated to evaluate the corrosion capabilities of Pb-Bi eutectic (LBE) and Pb-Au eutectic (LGE). It is found that LBE has more severe corrosion capability than LGE. The energetic calculation is further developed in evaluating the effect of alloying elements in popular steels on the dissolution corrosion. The results indicate that Si, V, Nb and Mo may mitigate the dissolution corrosion of martensite steels in liquid Pb, Bi and Au.
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When used as a protective scale, the Fe3O4 layer covering the stainless steel surface in accelerator driven subcritical systems (ADS) is corroded by liquid lead-bismuth eutectics (LBE). By performing theoretical calculations, we reveal that both Pb and Bi at the interface between the LBE and the Fe3O4 scale, favorably adsorb onto the Fe3O4 surfaces, weakening the strength of Fe-O bonds nearby significantly. This facilitates the movement of iron atoms toward the deposited Pb(Bi) and away from the Fe3O4 surface, thus causing corrosion. Such corrosion behavior becomes severe if oxygen vacancies exist in the surface region.
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Microgels are soft particles that can be deformed and compressed, which would induce intriguing phase behaviors at high packing fractions. Poly(N-isopropylacrylamide) (PNIPAM) microgels, with a lower critical solution temperature (LCST) of 33 °C, have attracted considerable interests as model colloids, since the volume of them and the interaction between the microgels can be tuned precisely by temperature. In this work, the linear viscoelastic properties of PNIPAM microgel suspensions have been investigated using mechanical spectroscopy. A particular attention is focused on the phase behaviors at high concentrations. With increasing concentration the system undergoes a repulsive glass-to-gel transition below the LCST, while, as temperature is raised across the LCST, the system undergoes a gel-to-attractive glass transition. A mechanism of these transitions for the microgels is proposed based on the directional interaction between the particles. In moderate concentration or de-swelling microgels the interaction is isotropic leading to the glass phase, while in concentrated and deformed microgels the interaction is directional leading to the gel phase. Our results enrich the current understanding of the phase transition in microgel systems and shed new light on the phase diagram of colloidal suspensions in general.