A multiscale optimisation method for bone growth scaffolds based on triply periodic minimal surfaces.

Tissue engineered bone scaffolds are potential alternatives to bone allografts and autografts. Porous scaffolds based on triply periodic minimal surfaces (TPMS) are good candidates for tissue growth because they offer high surface-to-volume ratio, have tailorable stiffness, and can be easily fabricated by additive manufacturing. However, the range of TPMS scaffold types is extensive, and it is not yet clear which type provides the fastest cell or tissue growth while being sufficiently stiff to act as a bone graft. Nor is there currently an established methodology for TPMS bone scaffold design which can be quickly adopted by medical designers or biologists designing implants. In this study, we examine six TPMS scaffold types for use as tissue growth scaffolds and propose a general methodology to optimise their geometry. At the macro-scale, the optimisation routine ensures a scaffold stiffness within suitable limits for bone, while at the micro-scale it maximises the cell growth rate. The optimisation procedure also ensures the scaffold pores are of sufficient diameter to allow oxygen and nutrient delivery via capillaries. Of the examined TPMS structures, the Lidinoid and Split P cell types provide the greatest cell growth rates and are therefore the best candidates for bone scaffolds.

3D-printed components for quantum devices.

Recent advances in the preparation, control and measurement of atomic gases have led to new insights into the quantum world and unprecedented metrological sensitivities, e.g. in measuring gravitational forces and magnetic fields. The full potential of applying such capabilities to areas as diverse as biomedical imaging, non-invasive underground mapping, and GPS-free navigation can only be realised with the scalable production of efficient, robust and portable devices. We introduce additive manufacturing as a production technique of quantum device components with unrivalled design freedom and rapid prototyping. This provides a step change in efficiency, compactness and facilitates systems integration. As a demonstrator we present an ultrahigh vacuum compatible ultracold atom source dissipating less than ten milliwatts of electrical power during field generation to produce large samples of cold rubidium gases. This disruptive technology opens the door to drastically improved integrated structures, which will further reduce size and assembly complexity in scalable series manufacture of bespoke portable quantum devices.

An inverse method for determining the spatially resolved properties of viscoelastic-viscoplastic three-dimensional printed materials.

A method using experimental nanoindentation and inverse finite-element analysis (FEA) has been developed that enables the spatial variation of material constitutive properties to be accurately determined. The method was used to measure property variation in a three-dimensional printed (3DP) polymeric material. The accuracy of the method is dependent on the applicability of the constitutive model used in the inverse FEA, hence four potential material models: viscoelastic, viscoelastic-viscoplastic, nonlinear viscoelastic and nonlinear viscoelastic-viscoplastic were evaluated, with the latter enabling the best fit to experimental data. Significant changes in material properties were seen in the depth direction of the 3DP sample, which could be linked to the degree of cross-linking within the material, a feature inherent in a UV-cured layer-by-layer construction method. It is proposed that the method is a powerful tool in the analysis of manufacturing processes with potential spatial property variation that will also enable the accurate prediction of final manufactured part performance.

Nuclear magnetic resonance measurements of velocity distributions in an ultrasonically vibrated granular bed.

We report the results of nuclear magnetic resonance imaging experiments on granular beds of mustard grains fluidized by vertical vibration at ultrasonic frequencies. The variation of both granular temperature and packing fraction with height was measured within the three-dimensional cell for a range of vibration frequencies, amplitudes and numbers of grains. Small increases in vibration frequency were found--contrary to the predictions of classical 'hard-sphere' expressions for the energy flux through a vibrating boundary--to result in dramatic reductions in granular temperature. Numerical simulations of the grain-wall interactions, using experimentally determined Hertzian contact stiffness coefficients, showed that energy flux drops significantly as the vibration period approaches the grain-wall contact time. The experiments thus demonstrate the need for new models for 'soft-sphere' boundary conditions at ultrasonic frequencies.

A hybrid approach to determining cornea mechanical properties in vivo using a combination of nano-indentation and inverse finite element analysis.

An analysis of the material properties of porcine corneas has been performed. A simple stress relaxation test was performed to determine the viscoelastic properties and a rheological model was built based on the Generalized Maxwell (GM) approach. A validation experiment using nano-indentation showed that an isotropic GM model was insufficient for describing the corneal material behaviour when exposed to a complex stress state. A new technique was proposed for determining the properties, using a combination of nano-indentation experiment, an isotropic and orthotropic GM model and inverse finite element method. The good agreement using this method suggests that this is a promising technique for measuring material properties in vivo and further work should focus on the reliability of the approach in practice.

Kinetics of a frictional granular motor.

Within the framework of a Boltzmann-Lorentz equation, we analyze the dynamics of a granular rotor immersed in a bath of thermalized particles in the presence of a frictional torque on the axis. In numerical simulations of the equation, we observe two scaling regimes at low and high bath temperatures. In the large friction limit, we obtain the exact solution of a model corresponding to asymptotic behavior of the Boltzmann-Lorentz equation. In the limit of large rotor mass and small friction, we derive a Fokker-Planck equation for which the exact solution is also obtained.

A new atomization cell for trace metal determinations by tungsten coil atomic spectrometry.

A new metallic atomization cell is used for trace metal determinations by tungsten coil atomic absorption spectrometry and tungsten coil atomic emission spectrometry. Different protecting gas mixtures are evaluated to improve atomic emission signals. Ar, N(2), CO(2) and He are used as solvents, and H(2) and C(2)H(2) as solutes. A H(2)/Ar mixture provided the best results. Parameters such as protecting gas flow rate and atomization current are also optimized. The optimal conditions are used to determine the figures of merit for both methods and the results are compared with values found in the literature. The new cell provides a better control of the radiation reaching the detector and a small, more isothermal environment around the atomizer. A more concentrated atomic cloud and a smaller background signal result in lower limits of detection using both methods. Cu (324.7 nm), Cd (228.8 nm) and Sn (286.3 nm) determined by tungsten coil atomic absorption spectrometry presented limits of detection as low as 0.6, 0.1, and 2.2 µg L(-1), respectively. For Cr (425.4 nm), Eu (459.4 nm) and Sr (460.7 nm) determined by tungsten coil atomic emission spectrometry, limits of detection of 4.5, 2.5, and 0.1 µg L(-1) were calculated. The method is used to determine Cu, Cd, Cr and Sr in a water standard reference material. Results for Cu, Cd and Cr presented no significant difference from reported values in a 95% confidence level. For Sr, a 113% recovery was obtained.

Moderate Wine Consumption Inhibits the Development of the Metabolic Syndrome: The Study of Women's Health Across the Nation (SWAN).

We investigated the relationship between wine consumption and the metabolic syndrome (MetS) in a longitudinal, eight-year study of the natural history of the menopause transition at seven geographical sites in the United States. Although similar in age, the 527 African American women had a worse metabolic profile than 1057 Caucasian women. Moderate wine consumption (one glass/day) was less common among African American women but was associated with a better lipid profile in both ethnic groups. Compared to women who drank one glass of wine per day, those who consumed no wine had twice the risk of developing the MetS.

The relationship between psychosocial status, acculturation and country of origin in mid-life Hispanic women: data from the Study of Women's Health Across the Nation (SWAN).

METHOD: To test the hypothesis that psychosocial symptomatology differs by country of origin and acculturation among Hispanic women, we examined 419 women, aged 42-52 years at baseline, enrolled in the New Jersey site of the Study of Women's Health Across the Nation (SWAN). Women were categorized into six groups: Central (CA, n = 29) or South American (SA, n = 106), Puerto Rican (PR, n = 56), Dominican (D, n = 42), Cuban (Cu, n = 44) and non-Hispanic Caucasian (NHC, n = 142). Acculturation, depressive symptoms, hostility/cynicism, mistreatment/discrimination, sleep quality, social support, and perceived stress were assessed at baseline. Physical functioning, trait anxiety and anger were assessed at the fourth annual follow-up. Comparisons between Hispanic and non-Hispanic Caucasians used χ², t test or non-parametric alternatives; ANOVA or Kruskal-Wallis testing examined differences among the five Hispanic sub-groups. Multivariable regression models used PR women as the reference group. RESULTS: Hispanic women were overall less educated, less acculturated (p < 0.001 for both) and reported more depressive symptoms, cynicism, perceived stress, and less mistreatment/discrimination than NHCs. Along with D women, PR women reported worse sleep than Cu women (p < 0.01) and more trait anxiety than SA and Cu women (p < 0.01). Yet, PR women were most acculturated (21.4% highly acculturated vs. CA (0.0%), D (4.8%), SA (4.8%) and Cu (2.3%) women; p < 0.001). In regression models, PR women reported depressive symptoms more frequently than D, Cu, or SA women, and reported trait anxiety more frequently than Cu or SA women. Greater acculturation was associated with more favorable psychosocial status, but PR ethnicity was negatively related to psychosocial status. CONCLUSION: Psychosocial symptomatology among Hispanic women differs by country of origin and the relatively adverse profile of Puerto Rican women is not explained by acculturation.

Menopausal symptoms within a Hispanic cohort: SWAN, the Study of Women's Health Across the Nation.

INTRODUCTION: Since the designation of people as Hispanic involves the amalgamation of a number of different cultures and languages, we sought to test the hypothesis that menopausal symptoms would differ among Hispanic women, based upon country of origin and degree of acculturation. METHODS: A total of 419 women, aged 42-52 years at baseline, were categorized as: Central American (CA, n = 29) or South American (SA, n = 106), Puerto Rican (PR, n = 56), Dominican (D, n = 42), Cuban (Cu, n = 44) and non-Hispanic Caucasian (n = 142). We assessed vasomotor symptoms, vaginal dryness and trouble in sleeping. Hispanics and non-Hispanic Caucasians were compared using the chi(2) test, t test or non-parametric alternatives; ANOVA or Kruskal-Wallis testing examined differences among the five Hispanic sub-groups. Multivariable regression models used PR women as the reference group. RESULTS: Hispanic women were overall less educated, less acculturated (p < 0.001 for both) than non-Hispanic Caucasians and more of them reported vasomotor symptoms (34.1-72.4% vs. 38.3% among non-Hispanic Caucasians; p = 0.0293) and vaginal dryness (17.9-58.6% vs. 21.1% among non-Hispanic Caucasians, p = 0.0287). Among Hispanics, more CA women reported vasomotor symptoms than D, Cu, SA, or PR women (72.4% vs. 45.2%, 34.1%, 50.9%, and 51.8%, respectively). More CA (58.6%) and D women (38.1%) reported vaginal dryness than PR (17.9%), Cu (25.0%) and SA (31.4%) women. More PR and D women reported trouble in sleeping (66.1 and 64.3%, respectively) compared to CA (51.7%), Cu (36.4%), and SA (45.3%) women. CONCLUSION: Symptoms associated with menopause among Hispanic women differed by country of origin but not acculturation. Central American women appear to be at greatest risk for both vasomotor symptoms and vaginal dryness.

Adipocytokine and ghrelin levels in relation to cardiovascular disease risk factors in women at midlife: longitudinal associations.

BACKGROUND: There are limited data concerning the relationships between changes in adipocytokines and cardiovascular disease (CVD) risk factors. OBJECTIVE: To examine the longitudinal associations between leptin, adiponectin, resistin and ghrelin levels and CVD risk factor levels in women at midlife. DESIGN: Prospective, observational study. SUBJECTS AND MEASUREMENTS: Leptin, adiponectin, resistin, ghrelin levels and CVD risk factors were measured in specimens collected from 40 women at 3 points in time corresponding to the pre-, peri- and postmenopause stages of their natural menopause transition. RESULTS: In longitudinal analyses adjusted for CVD risk factors and leptin at the previous menopausal stage, aging, education, smoking and physical activity, greater increases in leptin over the menopause transition were associated with greater decreases in high-density lipoprotein cholesterol (HDL-c) and greater increases in diastolic blood pressure, glucose, insulin and insulin resistance (all P < 0.05). Larger decreases in adiponectin over the menopause transition were associated with greater increases in systolic blood pressure, insulin and insulin resistance and with greater decreases in HDL-c. Greater increases in ghrelin levels over the menopausal transition were associated with greater low-density lipoprotein cholesterol increases (P = 0.014). Resistin was not associated with CVD risk factor changes. CONCLUSION: There were significant adverse associations of adipocytokines and ghrelin with multiple CVD risk factor changes in women across midlife. Given that this time period is dynamic for CVD risk, these data underscore the need for additional prospective studies.

Correlation of simple imaging tests and coronary artery calcium measured by computed tomography in hemodialysis patients.

Vascular calcification is associated with an adverse prognosis in end-stage renal disease. It can be accurately quantitated with computed tomography but simple in-office techniques may provide equally useful information. Accordingly we compared the results obtained with simple non-invasive techniques with those obtained using electron beam tomography (EBT) for coronary artery calcium scoring (CACS) in 140 prevalent hemodialysis patients. All patients underwent EBT imaging, a lateral X-ray of the lumbar abdominal aorta, an echocardiogram, and measurement of pulse pressure (PP). Calcification of the abdominal aorta was semiquantitatively estimated with a score (Xr-score) of 0-24 divided into tertiles, echocardiograms were graded as 0-2 for absence or presence of calcification of the mitral and aortic valve and PP was divided in quartiles. The CACS was elevated (mean 910+/-1657, median 220). The sensitivity and specificity for CACS > or = 100 was 53 and 70%, for calcification of either valve and 67 and 91%, respectively, for Xr-score > or = 7. The area under the curve for CACS > or = 100 associated with valve calcification and Xr-score was 0.62 and 0.78, respectively. The likelihood ratio (95% confidence interval) of CACS > or = 100 was 1.79 (1.09, 2.96) for calcification of either valve and 7.50 (2.89, 19.5) for participants with an Xr-score > or = 7. In contrast, no association was present between PP and CACS. In conclusion, simple measures of cardiovascular calcification showed a very good correlation with more sophisticated measurements obtained with EBT. These methodologies may prove very useful for in-office imaging to guide further therapeutic choices in hemodialysis patients.

A randomized controlled trial of dietary fiber intake on serum lipids.

OBJECTIVE: Clinical trials have indicated that water-soluble fiber from oats reduces serum cholesterol among hypercholesterolemic patients on a low-fat diet. We examined the effect of dietary fiber intake on serum lipids among persons without hypercholesterolemia. DESIGN: Randomized controlled trial. SETTING AND SUBJECTS: We recruited 110 participants who were aged 30-65 years and had a serum cholesterol level < 240 mg/dl from community. INTERVENTION: Study participants were randomly assigned to receive 8 g per day of water-soluble fiber from oat bran or a control intervention. RESULTS: At baseline, the mean levels of serum cholesterol and other measured variables were comparable between the high-fiber and control groups. Over the 3-month intervention, mean changes (95% confidence interval (CI)) in total, HDL-, and LDL-cholesterol were -2.42 mg/dl (-8.90 to 4.05 mg/dl; P = 0.46), -0.24 mg/dl (-2.19 to 1.71 mg/dl; P = 0.81), and -1.96 mg/dl (-7.32 to 3.40 mg/dl; P = 0.47) in the fiber group and -0.02 mg/dl (-5.29 to 5.26 mg/dl; P = 0.99), 1.42 mg/dl (-0.74 to 3.59 mg/dl; P = 0.19), and -0.64 mg/dl (-5.30 to 4.03 mg/dl; P = 0.79) in the control group, respectively. The net changes (95% confidence interval) in total, HDL-, and LDL-cholesterol were -2.40 mg/dl (-10.6 to 5.81 mg/dl; P = 0.56), -1.66 mg/dl (-4.55 to 1.22 mg/dl; P = 0.26) and -1.33 mg/dl (-8.33 to 5.68 mg/dl; P = 0.71), respectively. CONCLUSIONS: Our study does not support the hypothesis that water-soluble fiber intake from oat bran reduces total and LDL-cholesterol in study participants with a normal serum cholesterol level.

Convection in vibrated annular granular beds.

The response to vibration of a granular bed, consisting of a standard cylindrical geometry but with the addition of a dissipative cylindrical inner wall, has been investigated both experimentally (using positron emission particle tracking) and numerically (using hard sphere molecular dynamics simulation). The packing fraction profiles and granular temperature distributions (in both vertical and horizontal directions) were determined as a function of height and distance from the axis. The two sets of results were in reasonable agreement. The molecular dynamics simulations were used to explore the behavior of the granular bed in the inner wall-outer wall coefficient of restitution phase space. It was observed that one could control the direction of the toroidal convection rolls by manipulating the relative dissipation at the inner and outer walls via the coefficients of restitution, and with several layers of grains it was seen that double convection rolls could also be formed, a result that was subsequently confirmed experimentally.

Coexistence of two granular temperatures in binary vibrofluidized beds.

An investigation into the granular temperature distributions of a binary vibrofluidized granular bed has been conducted using positron emission particle tracking. By repeating each experiment with the tracer selected in turn from the two size components, the granular temperature and packing fraction distributions for each phase were determined. It was found that, for a range of size fractions, the granular temperature of the larger particles was higher than that of the smaller diameter grains, a result which was supported by a simple theoretical analysis based on the steady state energy equation.

Numerical solution of the Smoluchowski equation for a vibrofluidized granular bed.

A stochastic approach, similar to that used to describe Brownian motion, was used to model the displacement probability of grains in a three-dimensional vibrofluidized granular bed. As neither an analytical description nor measurements of the diffusion coefficients were available, the governing partial differential equation, namely, the Smoluchowski equation, was solved numerically using an iterative procedure, modifying the granular temperature profile at each step. The results of this stochastic model were compared to experimental measurements of the displacement probability density made using positron emission particle tracking. The results indicate that methods based on hard elastic systems such as the Smoluchowski equation are appropriate to granular systems, particularly over timescales greater than the mean collision time.

Tissue-specific alterations in lipoprotein lipase activity in copper-deficient rats.

Copper deficiency results in alterations in lipid metabolism that include elevations in serum cholesterol and triglycerides and a decrease in whole-body respiratory quotient. Copper-deficient animals are also leaner even though electron micrographs of the myocardium present increased lipid droplet accumulation. To address whether a compromised copper status impacts triglyceride deposition in a tissue-specific manner, the activity of lipoprotein lipase was measured in adipose tissue and cardiac and skeletal muscle. Weanling rats fed a copper-restricted diet (<1 ppm) for 6 wk demonstrated a greater than twofold increase in cardiac lipoprotein lipase activity concomitant with a significant reduction in adipose tissue lipoprotein lipase activity. Skeletal muscle lipoprotein lipase activity was not altered by the copper-deficient state. The results of this study suggest that copper deficiency may induce a tissue-specific alteration in lipoprotein lipase activity in rats, which may contribute to the notable deposition of lipid substance in myocardium and the concomitant general body leanness.

Granular temperature profiles in three-dimensional vibrofluidized granular beds.

The motion of grains in a three-dimensional vibrofluidized granular bed has been measured using the technique of positron emission particle tracking, to provide three-dimensional packing fraction and granular temperature distributions. The mean square fluctuation velocity about the mean was calculated through analysis of the short time mean squared displacement behavior, allowing measurement of the granular temperature at packing fractions of up to eta approximately 0.15. The scaling relationship between the granular temperature, the number of layers of grains, and the base velocity was determined. Deviations between the observed scaling exponents and those predicted by recent theories are attributed to the influence of dissipative grain-sidewall collisions.

Convection in highly fluidized three-dimensional granular beds.

Free, buoyancy-driven convection has been observed experimentally in three-dimensional highly fluidized granular flows for the first time. Positron emission particle tracking was used to determine the position of a tracer grain in a vibrofluidized bed, from which packing fraction distributions as well as the velocity fields could be determined. The convection rolls, although small compared to the magnitude of velocity fluctuations (<5%), were consistently observed for a range of grain numbers and shaker amplitudes. Density variations are a signature of free convection and, with negative temperature gradients also present, were interpreted as the mechanism by which the convection rolls were initiated.

The detection of malingering.

A 60-item paper-and-pencil inventory showed a 98% "hit-rate" in distinguishing between honest and simulated malingering protocols produced by 29 nonclinical subjects who took the inventory in both the honest and faked conditions. When instructed to take the Wildman Symptom Cheklist "as if applying for some kind of disability compensation," subjects endorsed a significantly higher number of the self-statements which appear clinically unbelievable. Independent replication is now required.