A novel actuator-internal micro/nano positioning stage with an arch-shape bridge type amplifier

This paper presents a novel actuator-internal two degree-of-freedom (2-DOF) micro/nano positioning stage actuated by piezoelectric (PZT) actuators, which can be used as a fine actuation part in dual-stage system. To compensate the positioning error of coarse stage and achieve a large motion stroke, a symmetrical structure with an arch-shape bridge type amplifier based on single notch circular flexure hinges is proposed and utilized in the positioning stage. Due to the compound bridge arm configuration and compact flexure hinge structure, the amplification mechanism can realize high lateral stiffness and compact structure simultaneously, which is of great importance to protect PZT actuators. The amplification mechanism is integrated into the decoupling mechanism to improve compactness, and to produce decoupled motion in X- and Y- axes. An analytical model is established to explore the static and dynamic characteristics, and the geometric parameters are optimized. The performance of the positioning stage is evaluated through finite element analysis (FEA) and experimental test. The results indicate that the stage can implement 2-DOF decoupled motion with a travel range of 55.4×53.2 μm2, and the motion resolution is 8 nm. The stage can be used in probe tip-based micro/nano scratching

Power of maximum HLOD tests to detect linkage to obesity genes

BACKGROUND: We investigate the power of heterogeneity LOD test to detect linkage when a trait is determined by several major genes using Genetic Analysis Workshop 13 simulated data. We consider three traits, two of which are disease-causing traits: 1) the rate of change in body mass index (BMI); and 2) the maximum BMI; and 3) the disease itself (hypertension). Of interest is the power of "HLOD2", the maximum heterogeneity LOD obtained upon maximizing over the two genetic models. RESULTS: Using a trait phenotype Obesity Slope, we observe that the power to detect the two markers closest to the two genes (S1, S2) at the 0.05 level using HLOD2 is 13% and 10%. The power of HLOD2 for Max BMI phenotype is 12% and 9%. The corresponding values for the Hypertension phenotype are 8% and 6%. CONCLUSION: The power to detect linkage to the slope genes is quite low. But the power using disease-related traits as a phenotype is greater than the power using the disease (hypertension) phenotype

Contact force sensing and control for inserting operation during precise assembly using a micromanipulator integrated with force sensors

This paper proposes a novel contact force sensing and control method for the inserting operation during precise assembly process, which is based on a micromanipulator integrated with force sensors. At first, theoretical analysis is carried out to calculate the admissible contact force between the gripped holes and the pegs. The contact force thresholds which are smaller than the admissible contact forces are adopted in the control algorithm to avoid the rotating of the gripped holes during assembly process. The force sensors are calibrated using an ATI force sensor and the conversing coefficients are calculated. The admissible contact forces are tested when different contact distance and preload force are adopted. The performance of the proposed contact force sensing and control method is verified by carrying out the task of applying contact force on the surface of the gripped holes with different contacting speeds. The results indicate that the contact force can be adjusted to be smaller than the threshold 1 and the peg-in-hole assembly can be completed successfully. Note to Practitioners—This paper proposes a novel contact force sensing method during the inserting operation. Compared with the traditional contact force sensing method, this paper adopts the force sensor integrated into the micromanipulator instead of commercial force sensor to detect the contact force between two parts. To ensure the assembling precision, the theoretical analysis is conducted to calculated the admissible contact force to avoid the sliding and rotating of the gripped micro part during assembling. This work efficiently simplifies the contact force sensing and control process, where complex calibration process needn’t to be carried out to eliminate the influence of the mass of the micromanipulator on the testing results. In addition, the assembling costs are reduced by replacing commercial force sensors with strain gauges

Influence of area-to-volume ratios on dissolution characteristics and mechanical properties of acid-corroded sandstone

To study the effect of area-to-volume ratio on the dissolution and deterioration characteristics of sandstone in the static acid-rock reaction system, the HCl and H2SO4 solutions with pH=2 and 5 are selected as corrosion environments, and the different area-to-volume ratios are set by changing surface areas of sandstone. The effects of area-to-volume ratios on the physicochemical and mechanical properties of sandstone are studied. According to the acid-rock reaction theory, the effect of the area-to-volume ratio on the diffusion-dissolution mechanism during sandstone corrosion is analyzed. The results show that the sandstone mass loss rate and amount of substance of total cations are all related to the corrosion time as a power function. The area-to-volume is positively correlated with the dissolution rate constant and has little effect on the reaction order. The reaction order is less than one in different environments, indicating that the sandstone corrosion rate decreases gradually with soaking time. In the pH=2、5 HCl solution and pH=2 H2SO4 solution, the amount of substance of cation shows N(Ca2+) > N(Na+) > N(Mg2+) > N(K+), and in the pH=5 H2SO4 solution, it is N(Na+) > N(Ca2+) > N(Mg2+) ≈N(K+). The acid-rock reaction can be summarized as two mechanisms: diffusion control and chemical reaction control. The two control parameters are negatively correlated with the area-to-volume ratio and positively with the pH value of solutions. The parameter values in the H2SO4 solutions are slightly larger than the corresponding values in the HCl solutions. The interaction between sandstone and acid in different conditions is dominated by the chemical reaction. The area-to-volume ratio significantly influences diffusion more than the chemical reaction. The mechanical properties of sandstone are weakened after acid corrosion. The damage of sandstone under uniaxial compression can be divided into four stages: compaction, elastic deformation, plastic yielding and post-peak. The peak strength and elastic modulus decrease, the peak strain increases, the brittleness declines, and the ductility is enhanced. The larger the area-to-volume ratio, the more severe the sandstone deterioration is. Overall, the smaller the pH value of solutions, the more prominent the effects of the area-to-volume ratio on the dissolution characteristics and mechanical properties of sandstone are, which is more obvious in the HCl solutions than in the H2SO4 solutions. The finding can provide theoretical references for the safety assessment and disaster prevention of rock mass engineering under an acidic environment

Meconium Atazanavir Concentrations and Early Language Outcomes in HIV-Exposed, Uninfected Infants with Prenatal Atazanavir Exposure

This is not the published version.OBJECTIVE: To investigate whether prenatal atazanavir (ATV) exposure, assessed by meconium antiretroviral quantification, predicts early child language outcomes. Prenatal ATV exposure previously was associated with poorer language development in one-year-olds. METHODS: Pregnant women with HIV and their uninfected infants enrolled in the SMARTT study. Meconium antiretroviral concentrations were quantified by liquid chromatography-tandem mass spectrometry. Language development at 1 year was assessed with MacArthur-Bates Communicative Development Inventory (CDI) and Bayley Scales of Infant and Toddler Development—Third Edition (Bayley-III). Late language emergence (LLE) was defined as ≥ one of four CDI scores ≤10th percentile for age. Associations between fetal ATV exposure timing and duration, meconium ATV concentration, and language outcomes were evaluated, adjusting for potential confounders. RESULTS: Through 2013, meconium samples were available from 175 of 432 infants with prenatal ATV exposure. Valid Bayley-III (n=93) and CDI (n=106) assessments also were available. After adjustment for potential confounders, higher ATV meconium concentrations were associated with lower LLE risk (P=0.04), and cumulative ATV exposure duration also was associated with higher Bayley-III Language scores (P=0.03). Maternal ATV duration and initiation week correlated with ATV meconium concentrations (positively and negatively, respectively). CONCLUSIONS: Higher meconium ATV concentrations were protective against developmental language delays at 1 year, suggesting the importance of fetal ATV detoxification into meconium. This information supports ATV exposure safety for infant language development. ATV is a preferred ARV for pregnant women with HIV, suggesting the importance of ATV safety investigations. Additionally, further pursuit of the influences on language development in HEU infants is required

Sertraline Pharmacokinetics in HIV-Infected and Uninfected Children, Adolescents, and Young Adults

Objective: Due to potential disease and drug interactions, the appropriate sertraline starting dose and titration range may require adjustment in pediatric patients living with HIV. This is the first report of sertraline pharmacokinetics in HIV-infected youth.Methods: IMPAACT P1080 was a multicenter pilot study describing psychiatric medication pharmacokinetics in HIV-infected and uninfected youth. Participants were stable on sertraline, >6 to <25 years old, and (1) HIV-uninfected (HIV(–)), (2) HIV-infected taking efavirenz (EFV), or (3) HIV-infected taking boosting ritonavir/protease inhibitor (PI/r). Sampling occurred at pre-dose, 2, 4, 6, 12, and 24-h post-dose. Analyses were performed for sertraline and N-desmethylsertraline, and CYP2D6 phenotyping was completed with dextromethorphan.Results: Thirty-one participants (16 HIV(-), 12 PI/r, and 3 EFV) had median (range) weight, age, and dose of 69.5 (31.5–118.2) kg, 21.8 (9.1–24.7) years, and 75.0 (12.5–150.0) mg once daily. Sertraline exposure was highest for HIV(–) and lowest for EFV cohorts; median dose-normalized AUC0−24 was 1176 (HIV(–)), 791 (PI/r) and 473 (EFV) ng*hr/mL, and C24 was 32.7 (HIV(–)), 20.1 (PI/r), and 12.8 (EFV) ng/mL. The urinary dextromethorphan/dextrorphan (DXM/DXO) ratio was higher in HIV(–) vs. PI/r cohorts (p = 0.01). Four HIV(–) participants were CYP2D6 poor metabolizers (ln(DXM/DXO) of >-0.5).Conclusions: HIV(–) cohort had the highest sertraline exposure. Sertraline exposure was ~40% lower in the PI/r cohort than in HIV(–); the need to alter sertraline dose ranges for PI/r participants is not clear. The impact of efavirenz on sertraline needs further investigation due to limited numbers of EFV participants

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Correction to: Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

The original version of this article unfortunately contained a mistake

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat