Large-scale atom probe tomography data mining: methods and application to inform hydrogen behavior

A large number of atom probe tomography (APT) datasets from past experiments were collected into a database to conduct statistical analyses. An effective way of handling the data is shown, and a study on hydrogen is conducted to illustrate the usefulness of this approach. We propose to handle a large collection of APT spectra as a point cloud and use a city block distance-based metric to measure dissimilarity between spectra. This enables quick and automated searching for spectra by similarity. Since spectra from APT experiments on similar materials are similar, the point cloud of spectra contains clusters. Analysis of these clusters of spectra in this point cloud allows us to infer the sample materials. The behavior of contaminant hydrogen is analyzed and correlated with voltage, electric field, and sample base material. Across several materials, the H2+ /H+ ratio is found to decrease with increasing field, likely an indication of postionization of H2+ ions. The absolute amounts of H2+ and H+ are found to frequently increase throughout APT experiments

The Pittsburgh randomized trial of tacrolimus compared to cyclosporine for hepatic transplantation

BACKGROUND: Tacrolimus (formerly FK 506) was first used clinically in 1989 to successfully replace cyclosporine in hepatic transplant recipients who were experiencing intractable rejection or as the baseline drug from the time of operation. After extensive pilot experience, an institutional review board-mandated clinical trial comparing cyclosporine with tacrolimus was performed. STUDY DESIGN: From February 16, 1990 to December 26, 1991, 154 patients were recruited. The competing drugs were combined with equal induction doses of prednisone in both arms of the study for the first 81 patients and with subsequently higher doses of prednisone in the remaining 35 patients who received cyclosporine and were entered into the trial. Drug crossover was permitted for lack of efficacy or adverse events. End points were rejection confirmed by biopsy and treatment failure leading to retransplantation or death. RESULTS: Seventy-nine patients were randomized to the tacrolimus arm and 75 to the cyclosporine arm during 1990 and 1991. All patients were available for follow-up throughout the trial, which terminated on May 30, 1995. The mean duration of follow-up was four years. Patients randomized to the tacrolimus arm were less likely to experience acute rejection than were those receiving cyclosporine, with 36.2 percent of the patients receiving tacrolimus and 16.8 percent of the patients receiving cyclosporine showing freedom from rejection at one year (p=0.003, likelihood ratio test). Survival of patients over the course of the study was virtually the same in the two groups. CONCLUSIONS: Tacrolimus was more effective than cyclosporine in preventing acute rejection

Additive Manufacturing of Biomechanically Tailored Meshes for Compliant Wearable and Implantable Devices

Additive manufacturing (AM) of medical devices such as orthopedic implants and hearing aids is highly attractive because of AM’s potential to match the complex form and mechanics of individual human bodies. Externally worn and implantable tissue-support devices, such as ankle or knee braces, and hernia repair mesh, offer a new opportunity for AM to mimic tissue-like mechanics and improve both patient outcomes and comfort. Here, it is demonstrated how explicit programming of the toolpath in an extrusion AM process can enable new, flexible mesh materials having digitally tailored mechanical properties and geometry. Meshes are fabricated by extrusion of thermoplastics, optionally with continuous fiber reinforcement, using a continuous toolpath that tailors the elasticity of unit cells of the mesh via incorporation of slack and modulation of filament-filament bonding. It is shown how the tensile mesh mechanics can be engineered to match the nonlinear response of muscle, incorporate printed mesh into an ankle brace with directionally specific inversion stiffness, and present further concepts for tailoring their 3D geometry for medical applications.Financial support was provided by a National Science Foundation Science, Engineering, and Education for Sustainability postdoctoral fellowship (Award number: 1415129) to S.W.P.; a Samsung Scholarship to J.L; the School of Engineering and Sciences from Tecnologico de Monterrey to R.R.; the Manufacturing Demonstration Facility, Oak Ridge National Laboratory, the Department of Energy, UT-Batelle, Oak Ridge Associated Universities, the DOE’s Advanced Manufacturing Office to G.D.; the German Academic Exchange Service (DAAD) to C.M.; and the Eric P. and Evelyn E. Newman Fund and NSF-CRCNS-1724135 to N.H

Demagnetization of Quantum Dot Nuclear Spins: Breakdown of the Nuclear Spin Temperature Approach

The physics of interacting nuclear spins arranged in a crystalline lattice is typically described using a thermodynamic framework: a variety of experimental studies in bulk solid-state systems have proven the concept of a spin temperature to be not only correct but also vital for the understanding of experimental observations. Using demagnetization experiments we demonstrate that the mesoscopic nuclear spin ensemble of a quantum dot (QD) can in general not be described by a spin temperature. We associate the observed deviations from a thermal spin state with the presence of strong quadrupolar interactions within the QD that cause significant anharmonicity in the spectrum of the nuclear spins. Strain-induced, inhomogeneous quadrupolar shifts also lead to a complete suppression of angular momentum exchange between the nuclear spin ensemble and its environment, resulting in nuclear spin relaxation times exceeding an hour. Remarkably, the position dependent axes of quadrupolar interactions render magnetic field sweeps inherently non-adiabatic, thereby causing an irreversible loss of nuclear spin polarization.Comment: 15 pages, 3 figure

Study protocol: a randomised controlled trial investigating the effect of exercise training on peripheral blood gene expression in patients with stable angina

Background: Exercise training has been shown to reduce angina and promote collateral vessel development in patients with coronary artery disease. However, the mechanism whereby exercise exerts these beneficial effects is unclear. There has been increasing interest in the use of whole genome peripheral blood gene expression in a wide range of conditions to attempt to identify both novel mechanisms of disease and transcriptional biomarkers. This protocol describes a study in which we will assess the effect of a structured exercise programme on peripheral blood gene expression in patients with stable angina, and correlate this with changes in angina level, anxiety, depression, and exercise capacity. Methods/Design: Sixty patients with stable angina will be recruited and randomised 1: 1 to exercise training or conventional care. Patients randomised to exercise training will attend an exercise physiology laboratory up to three times weekly for supervised aerobic interval training sessions of one hour in total duration. Patients will undergo assessments of angina, anxiety, depression, and peripheral blood gene expression at baseline, after six and twelve weeks of training, and twelve weeks after formal exercise training ceases. Discussion: This study will provide comprehensive data on the effect of exercise training on peripheral blood gene expression in patients with angina. By correlating this with improvement in angina status we will identify candidate peripheral blood transcriptional markers predictive of improvements in angina level in response to exercise training

Fixed points and amenability in non-positive curvature

Consider a proper cocompact CAT(0) space X. We give a complete algebraic characterisation of amenable groups of isometries of X. For amenable discrete subgroups, an even narrower description is derived, implying Q-linearity in the torsion-free case. We establish Levi decompositions for stabilisers of points at infinity of X, generalising the case of linear algebraic groups to Is(X). A geometric counterpart of this sheds light on the refined bordification of X (\`a la Karpelevich) and leads to a converse to the Adams-Ballmann theorem. It is further deduced that unimodular cocompact groups cannot fix any point at infinity except in the Euclidean factor; this fact is needed for the study of CAT(0) lattices. Various fixed point results are derived as illustrations.Comment: 33 page

Evidence of increased islet cell proliferation in patients with recent-onset type 1 diabetes.

addresses: Institute of Biomedical and Clinical Science, Peninsula College of Medicine and Dentistry (University of Exeter), Tamar Science Park, Derriford, Plymouth, UK.The final publication is available at link.springer.com/article/10.1007%2Fs00125-010-1817-6In adults, the rate of beta cell replication is normally very low, but recent evidence suggests that it may increase during insulitis. We therefore studied tissue from donors with recent-onset type 1 diabetes to establish whether islet cell proliferation is increased during the disease process

Human Computation and Convergence

Humans are the most effective integrators and producers of information, directly and through the use of information-processing inventions. As these inventions become increasingly sophisticated, the substantive role of humans in processing information will tend toward capabilities that derive from our most complex cognitive processes, e.g., abstraction, creativity, and applied world knowledge. Through the advancement of human computation - methods that leverage the respective strengths of humans and machines in distributed information-processing systems - formerly discrete processes will combine synergistically into increasingly integrated and complex information processing systems. These new, collective systems will exhibit an unprecedented degree of predictive accuracy in modeling physical and techno-social processes, and may ultimately coalesce into a single unified predictive organism, with the capacity to address societies most wicked problems and achieve planetary homeostasis.Comment: Pre-publication draft of chapter. 24 pages, 3 figures; added references to page 1 and 3, and corrected typ

Drug eluting balloons for de novo coronary lesions - a systematic review and meta-analysis

The role of drug-eluting balloons (DEB) is unclear. Increasing evidence has shown a benefit for the treatment of in-stent restenosis. Its effect on de novo coronary lesions is more controversial. Several smaller randomized trials found conflicting results

A model for reactive porous transport during re-wetting of hardened concrete

A mathematical model is developed that captures the transport of liquid water in hardened concrete, as well as the chemical reactions that occur between the imbibed water and the residual calcium silicate compounds residing in the porous concrete matrix. The main hypothesis in this model is that the reaction product -- calcium silicate hydrate gel -- clogs the pores within the concrete thereby hindering water transport. Numerical simulations are employed to determine the sensitivity of the model solution to changes in various physical parameters, and compare to experimental results available in the literature.Comment: 30 page