Publications

This paper describes a synthesis of free-standing, 10−15-nm-thick polymer films of well-defined lateral size and shape. The three key elements of this procedure are (1) formation by microcontact printing (μCP) of a patterned, self-assembled monolayer (SAM) with hydrophobic regions (alkane-terminated) and adsorption-resistant regions (oligo(ethylene oxide)-terminated); (2) initiation of spatially selective growth of films of poly(electrolyte) multilayers by adsorption on the hydrophobic regions of the patterned SAM; and (3) dry transfer of these films to a water-soluble sacrificial backing, from which the films can be released into solution. This technique exploits the hydrophobic effect as an interaction that can be switched off when it is not needed: during the growth of the films in aqueous buffer, the hydrophobic effect anchors the polymers to the surface; once these films have been dried after synthesis, they are bound to the substrate only by van der Waals interactions and can be transferred nondestructively to a sacrificial backing. The growth and final state of the films were characterized using surface plasmon resonance (SPR), polarized infrared external reflectance spectroscopy (PIERS), ellipsometry, fluorescence microscopy, and atomic force microscopy (AFM).

We have studied the trigonal warping effect in metallic carbon nanotubes using resonance Raman scattering and examining the G ′-band profile for individual metallic single-wall carbon nanotubes. We show that the observed splitting in the G ′-band phonon spectra is directly correlated with the splitting in the singularities of the joint density of electronic states, i.e., detailed information about the 1D electronic structure is extracted from a phonon measurement. By correlating the phonon data with the calculated electronic structure for several (n,m) nanotubes, we were able to determine the G ′-band dispersion [(∂ωG′ /∂E laser )=108±6 cm −1/eV] by using a single laser energy.

This work demonstrates that a soft, toroidal hydrostat can be used to perform three functions found in both living and engineered systems: gripping, catching, and conveying. We first demonstrate a gripping mechanism that uses linear motion to drive the inversion of the toroid around objects, encapsulating them within a crumpled elastic membrane under hydrostatic pressure. This mechanism results in gripping forces ranging from 1–80 N, which depend predictably upon the geometric and material properties of the gripper and the object. We next demonstrate a catching mechanism akin to that of a chameleon’s tongue: the elasticity of the membrane is used to store mechanical energy and drive a rapid acceleration and inversion process (≈400 m/s2) to capture flying objects (e.g., a bouncing ball). Finally, we show how the soft topological structure can be implemented in a soft conveying mechanism which continuously inverts and passes objects through its center (~1 cm/s), serving a function like that of esophageal peristalsis (i.e., transporting objects through a tube), while eliminating the requirement of a lubricated interface and the coordinated actuation of a pressure wave. The hybrid hard-soft mechanisms presented here can be applied in the integration of soft functionality into conventional robotic systems for applications including the automation of agricultural and biological research processes. More generally, we show how inflatable structures comprising soft polymeric films arranged in complex topologies provide a promising approach to designing soft robotic systems with novel, bio-inspired functionality.

This letter describes the fabrication of ∼80 nm structures in silicon, silicon dioxide, and gold substrates by exposing the substrates to a beam of metastable argon atoms in the presence of dilute vapors of trimethylpentaphenyltrisiloxane, the dominant constituent of diffusion pump oil used in these experiments. The atoms release their internal energy upon contacting the siloxanes physisorbed on the surface of the substrate, and this release causes the formation of a carbon-based resist. The atomic beam was patterned by a silicon nitride membrane, and the pattern formed in the resist material was transferred to the substrates by chemical etching. Simultaneous exposure of large areas (44 cm2) was also demonstrated.

In high-dimensional data, structured noise caused by observed and unobserved factors affecting multiple target variables simultaneously, imposes a serious challenge for modeling, by masking the often weak signal. Therefore, (1) explaining away the structured noise in multiple-output regression is of paramount importance. Additionally, (2) assumptions about the correlation structure of the regression weights are needed. We note that both can be formulated in a natural way in a latent variable model, in which both the interesting signal and the noise are mediated through the same latent factors. Under this assumption, the signal model then borrows strength from the noise model by encouraging similar effects on correlated targets. We introduce a hyperparameter for the latent signal-to-noise ratio which turns out to be important for modelling weak signals, and an ordered infinite-dimensional shrinkage prior that resolves the rotational unidentifiability in reduced-rank regression models. Simulations and prediction experiments with metabolite, gene expression, FMRI measurement, and macroeconomic time series data show that our model equals or exceeds the state-of-the-art performance and, in particular, outperforms the standard approach of assuming independent noise and signal models.

Background Recent studies have indicated that low back pain (LBP) is common already in adolescence, but only few studies have evaluated the factors that determine LBP-related health care use at this age. Methods The study population included 1987 adolescents aged 18 from the Oulu Back Study, a subcohort of the 1986 Northern Finland Birth Cohort. We used logistic regression to evaluate whether enabling resources, need factors, personal health habits or psychological problems are associated with seeking health care for LBP, among adolescents reporting LBP during the last year. Results Of the 1987 respondents, 50% of the females and 42% of the males reported having had LBP during the previous year. Of the 921 respondents with LBP, 89 (16%) females, and 59 (16%) males had consulted a health care professional. In both genders, pain intensity was strongly associated with seeking care [visual analogue scale (VAS) 8–10 vs. VAS 0–3; males: OR 16.6, 95% CI 3.8–72.5, females: OR 18.8 95% CI 6.3–56.1]. In addition, LBP-related daily activity limitations (impairment index 4–6 vs. 0 OR 15.7 95% CI 1.7–142.5) were associated with care seeking among males. Student status was also associated with care seeking among males (OR 2.34 95% CI 1.02–5.36). Conclusions Approximately one out of six adolescents with LBP seeks medical care. Intensity of pain and daily activity limitations appear to be the main determinants of seeking care for LBP in adolescence.

These data provide evidence that higher levels of midlife physical activity are associated with exceptional health status among women who survive to older ages and corroborate the potential role of physical activity in improving overall health.

Introduction/Background Persistent infection with high-risk human papillomavirus (HPV) is causally associated with cervical cancer. However, only ∼1% of women with HPV infection progress to cervical neoplasia (CIN). It is estimated that heritability may explain 25–30% of total variation in liability for cervical cancer. Common genetic variants have been detected in HLA (Human Leukocyte Antigen) regions responsible for the immune response, but this is not well understood. We aimed to conduct the largest genome-wide association study (GWAS) of cervical cancer to date, using UK Biobank data to identify genetic polymorphisms associated with CIN and cervical cancer. Methodology Using phenotypic data available from linked UK cancer registries, hospital ICD-10 records, operative procedures and participant interviews we identified 6378 women with CIN3/cervical cancer and 198,441 controls. With UK Biobank genotyping calls (Affymetrix UK Biobank Axiom® array) we conducted genome wide analyses, adjusting for population structure and potential confounders. As a stringent correction for multiple testing, we considered a pre-test significance level of 10-8 to declare single nucleotide polymorphisms (SNPs). Results In the first UK Biobank iteration we have identified potential SNPs (p Conclusion We observed genetic variants significantly associated with CIN3/cervical cancer in both cohorts. Loci within the MHC may affect susceptibility to development of CIN3/cervical cancer through altered immune responses. We will next undertake fine-mapping within the UK Biobank cohort, to further classify any novel causal variants that may explain the estimated genetic susceptibility to cervical cancer. Disclosure Funding provided by an NIHR Academic Clinical Fellowship (SL) and a Wellcome Trust Clinician Scientist Fellowship (SL). No conflicts of interest to declare.

Affinity capillary electrophoresis and protein charge ladders are used together to measure the contributions of long-range electrostatic interactions to binding of substituted benzene sulfonamide inhibitors to derivatives of human carbonic anhydrase II. The results are analyzed by continuum electrostatic calculations, which afford a detailed analysis of interactions of individual members of a population from a charge ladder. A Monte Carlo simulation of the experimental data using calculated contributions of individual lysine side chains to inhibitor binding shows that a large number of different patterns of acetylation are consistent with the experimental results. The calculations predict significant differences in the contributions of some lysines to ΔG and simulations suggest that experimental resolution must be enhanced to be able to measure such differences.

Muscle-actuated control is a research topic of interest spanning different fields, in particular biomechanics, robotics and graphics. This type of control is particularly challenging because models are often overactuated, and dynamics are delayed and non-linear. It is however a very well tested and tuned actuation model that has undergone millions of years of evolution and that involves interesting properties exploiting passive forces of muscle-tendon units and efficient energy storage and release. To facilitate research on muscle-actuated simulation, we release a 3D musculoskeletal simulation of an ostrich based on the MuJoCo simulator. Ostriches are one of the fastest bipeds on earth and are therefore an excellent model for studying muscle-actuated bipedal locomotion. The model is based on CT scans and dissections used to gather actual muscle data such as insertion sites, lengths and pennation angles. Along with this model, we also provide a set of reinforcement learning tasks, including reference motion tracking and a reaching task with the neck. The reference motion data are based on motion capture clips of various behaviors which we pre-processed and adapted to our model. This paper describes how the model was built and iteratively improved using the tasks. We evaluate the accuracy of the muscle actuation patterns by comparing them to experimentally collected electromyographic data from locomoting birds. We believe that this work can be a useful bridge between the biomechanics, reinforcement learning, graphics and robotics communities, by providing a fast and easy to use simulation.

Recently, the genetic variability at adiponectin locus (APM1) was associated with cardiovascular risk in patients with type 2 diabetes. We sought to examine the associations of five variants of APM1 gene (C-11365G, A-4034C, A-3964G, T45G, and G276T) with the risk of cardiovascular diseases (CVDs) in a larger cohort of diabetic patients. Of 879 diabetic men from the Health Professionals Follow-up Study, 239 participants developed coronary heart disease or stroke during 14 years of follow-up and 640 CVD-negative subjects were used as control subjects. The risk of CVD was significantly lower in TT homozygotes at locus +276 than in other genotypes under a recessive inheritance model after adjusting for age, BMI, smoking, alcohol consumption, physical activity, aspirin use, HbA1c, and history of hypertension or hypercholesterolemia (odds ratio 0.38 [95% CI 0.18–0.79]; P = 0.009). In the CVD-negative control subjects, the allele 276T was associated with significantly higher plasma adiponectin levels in a dose-dependent pattern (GG 14.8, GT 16.2, and TT 18.8 μg/ml) after adjusting for age, BMI, and other variables (P for trend = 0.0019). In conclusion, our study showed significant associations between APM1 G276T and decreased CVD risk and increased plasma adiponectin levels in diabetic men.

<p> </p> <p><em>Objective:</em> We examined whether intake of methyl donor nutrients, including vitamins B2, B6, and B12, and folate, from foods and/or supplements is associated with type 2 diabetes risk.</p> <p><em>Design and Methods:</em> We included 203,644 women and men from the Nurses' Health Study (1984-2016), Nurses' Health Study 2 (1991-2017), and Health Professionals Follow-Up Study (1986-2016). Dietary data were collected every 2-4 years using semi-quantitative food frequency questionnaires. Cox proportional hazards models with time-varying covariates were used to evaluate associations between each nutrient and type 2 diabetes risk. Cohort-specific hazard ratios were combined using inverse variance-weighted fixed effects meta-analyses.</p> <p><em>Results:</em> During 4,900,181 person-years of follow-up, we documented 19,475 incident type 2 diabetes cases. In multivariable-adjusted meta-analyses, participants in the highest quintile of total vitamin B2 and B6 intakes had lower risk of diabetes compared with those in the lowest quintile [HR(95% CI): 0.93(0.89, 0.98) for B2; 0.93(0.89, 0.97) for B6]. When stratified by source, significant associations remained for B2 from food, but not from supplements. Neither association for B6 from food or supplements attained significance. No association was observed between total B12 intake and diabetes. However, B12 from food was marginally associated with a higher diabetes risk [HR(95% CI): 1.05(1.00-1.11)], but not after additional adjustment for red meat intake [HR(95% CI): 1.04(0.99-1.10)]. No evidence of association was observed between intakes of folate and diabetes.</p> <p><em>Conclusions:</em> Our study suggests that higher intake of vitamin B2 and B6, especially B2 from food sources, may be associated with a modestly lower type 2 diabetes risk.</p>