Nanostructure development in polystyrene‐b‐polybutadiene‐b‐poly(methyl methacrylate) (SBM) thin films by atomic force microscopy: Effect of copolymer composition and solvent

Surface morphology development for SBM triblock copolymer thin films has been studied by atomic force microscopy. The effect of copolymer composition and solvent on the final morphology has been investigated. Obtained results indicated that depending on the block ratio (symmetric or asymmetric with minority middle block) and solvent, lamellar, hexagonal, cylindrical, or spheres in lamellae (ls)‐type morphologies can be achieved at film surfaces. The influence of the interaction parameters among blocks and solvents and cohesive energy values of block pairs on the final morphology has been proved. POLYM. ENG. SCI., 58:422–429, 2018. © 2017 Society of Plastics Engineers     

Effects of the Protonation State of Titratable Residues and the Presence of Water Molecules on Nocodazole Binding to β‐Tubulin

Regulation of microtubule assembly by antimitotic agents is a potential therapeutic strategy for the treatment of cancer, parasite infections, and neurodegenerative diseases. One of these agents is nocodazole (NZ), which inhibits microtubule polymerization by binding to β‐tubulin. NZ was recently co‐crystallized in Gallus gallus tubulin, providing new information about the features of interaction for ligand recognition and stability. In this work, we used state‐of‐the‐art computational approaches to evaluate the protonation effects of titratable residues and the presence of water molecules in the binding of NZ. Analysis of protonation states showed that residue E198 has the largest modification in its pK_a value. The resulting E198 pK_a value, calculated with pH‐REMD methodology (pK_a=6.21), was higher than the isolated E amino acid (pK_a=4.25), thus being more likely to be found in its protonated state at the binding site. Moreover, we identified an interaction between a water molecule and C239 and G235 as essential for NZ binding. Our results suggest that the protonation state of E198 and the structural water molecules play key roles in the binding of NZ to β‐tubulin.     

Anterior thoracoscopic epiphysiodesis in the treatment of a crankshaft phenomenon

OBJECTIVE: To determine if prone leg length measurements for inequality are valid to estimate standing X-ray measured differences. DESIGN: Leg length inequality (LLI) was measured, in millimeters, with each patient prone and with a standing X-ray, by an experienced chiropractor. Correlation between the two was calculated, and dependent t test performed. SETTING: Private chiropractic practice. PARTICIPANTS: The first 50 new patients with low back pain (LBP) who were X-rayed were included in the study. RESULTS: Correlation between the two variables was 0.71. Standard error of estimation was 5.4 mm. In 54% of subjects, the prone measurement was within 3 mm of the X-ray LLI; in 12%, however, opposite legs were identified as being "shorter" between the two methods. In 76% of patients, prone measurements were within 6 mm of X-ray, but there was 12-mm difference between the two measurement methods in 8% of the comparisons. CONCLUSIONS: Despite positive correlation, prone leg length measurements for inequality are not entirely valid estimates of standing X-ray differences. Large differences between prone and X-ray measurements in some cases indicate that one should be cautious when using the prone method alone to estimate leg length discrepancy. Additional research is needed to determine the causes of measurement differences between the two methods. Other methods for estimating standing leg length differential must be developed and evaluated for validity.     

High-fidelity spectrocardiography for the diagnosis of ischemic cardiopathy. The validation of a new method for analyzing the spectral components of the QRS complex

BACKGROUND: Analysis of high-frequency QRS complex envelope has been suggested as a method that could detect myocardial ischemia but the characteristics of the turbulence spectral from an spectral-temporal mapping into the QRS complex has not been studied yet. This is a prospective study of phase I for the validation of a new diagnostic test. AIMS: The aims for this study are: 1) To validate a new method for the detection of transient myocardial ischemia by both, high-frequency QRS and spectral turbulence analysis, which we have named "high-fidelity spectrocardiogram" (HFS). 2) To compare the sensitivity, specificity and accuracy of this HFS versus those obtained from nuclear medicine (NM-MIBI) and a conventional exercise ECG test, in a highly selected population. PATIENTS AND METHODS: Twenty-five patients (P) were studied: 10 P (Group B) with risk factors for coronary artery disease, without previous infarct, who had atypical precordial pain and a conventional ECG considered as "normal" by two cardiologists. The group A was formed by 15 P without risk factors or another kind of heart disease. All patients underwent a conventional surface ECG, which had to be normal in order to be considered for this study. Echocardiogram, exercise testing ECG and a NM-MIBI study were also normal. The HFS recording was taken before and after Dipyridamole testing, similar to the conventional method for the NM-MIBI (dipyridamole 0.25 mg/Kg/doses) studies. Our software for the analysis of QRS-frequencies was constructed from a language Turbo C++. The Fourier's transform allowed the construction of 3-dimensional graphics. After the determination of the best wide band for detecting changes in the frequency contained of QRS, the determination coefficients (r2) were obtained and compared before and after the challenge with dipyridamole. These changes were compared between groups (A vs B) later. RESULTS: The r2 changed more than 30% after dipyridamole in those patients in whom myocardial ischemia was demonstrated later by NM-MIBI. The sensitivity (85%) and specificity (90%) of HFS were similar to the nuclear medicine for identifying myocardial ischemia, but higher than a conventional exercise ECG testing (p.001). The main change in HFS was in the frequency-contained QRS in the 130-260 Hz band. The accuracy of our method was increased when an analysis of each orthogonal lead was made. There was a clear tendency of the group B to increase the QRS duration, while the contrary was found in group A, being the QRS the shorter (p.064). The chronological responses were different in those patients with ischemia. CONCLUSION: This study suggests that an episode of myocardial ischemia is able to change in a dramatic manner the frequency-contained within of the QRS complex, in spite of an unchanged ST segment in the conventional exercise ECG. We suggest that the HFS could be a good method for identifying myocardial ischemia. Its advantages could be important, particularly when the conventional exercise ECG is non informative.     

A Closed-Form Formula for the RBF-Based Approximation of the Laplace–Beltrami Operator

In this paper we present a method that uses radial basis functions to approximate the Laplace–Beltrami operator that allows to solve numerically diffusion (and reaction–diffusion) equations on smooth, closed surfaces embedded in \(\mathbb {R}^3\). The novelty of the method is in a closed-form formula for the Laplace–Beltrami operator derived in the paper, which involve the normal vector and the curvature at a set of points on the surface of interest. An advantage of the proposed method is that it does not rely on the explicit knowledge of the surface, which can be simply defined by a set of scattered nodes. In that case, the surface is represented by a level set function from which we can compute the needed normal vectors and the curvature. The formula for the Laplace–Beltrami operator is exact for radial basis functions and it also depends on the first and second derivatives of these functions at the scattered nodes that define the surface. We analyze the converge of the method and we present numerical simulations that show its performance. We include an application that arises in cardiology.     

Stability analysis of nonholonomic multiagent coordinate‐free formation control subject to communication delays

This paper investigates the convergence of nonholonomic multiagent coordinate‐free formation control to a prescribed target formation subject to communication delays by means of Lyapunov‐Krasovskii approach and smooth state‐feedback control laws. As a result, an iterative algorithm based on linear matrix inequalities is provided to obtain the worst‐case point‐to‐point delay under which the multiagent system is guaranteed to be stable. It is worth mentioning that: (i) the given algorithm holds for any connected communication topology and (ii) the formation control is coordinate‐free, that is, a common frame is not required to be shared between agents. The effectiveness of the given method is illustrated through simulation results.     

A linear optimization-based method for data privacy in statistical tabular data

National Statistical Agencies routinely disseminate large amount of data. Prior to dissemination these data have to be protected to avoid releasing confidential information. Controlled tabular adjustment (CTA) is one of the available methods for this purpose. CTA formulates an optimization problem that looks for the safe table which is closest to the original one. The standard CTA approach results in a mixed integer linear optimization (MILO) problem, which is very challenging for current technology. In this work we present a much less costly variant of CTA that formulates a multiobjective linear optimization (LO) problem, where binary variables are pre-fixed, and the resulting continuous problem is solved by lexicographic optimization. Extensive computational results are reported using both commercial (CPLEX and XPRESS) and open source (Clp) solvers, with either simplex or interior-point methods, on a set of real instances. Most instances were successfully solved with the LO-CTA variant in less than one hour, while many of them are computationally very expensive with the MILO-CTA formulation. The interior-point method outperformed simplex in this particular application.     

All‐Carbon Electrode Molecular Electronic Devices Based on Langmuir–Blodgett Monolayers

Nascent molecular electronic devices, based on monolayer Langmuir–Blodgett films sandwiched between two carbonaceous electrodes, have been prepared. Tightly packed monolayers of 4‐((4‐((4‐ethynylphenyl)ethynyl)phenyl)ethynyl)benzoic acid are deposited onto a highly oriented pyrolytic graphite electrode. An amorphous carbon top contact electrode is formed on top of the monolayer from a naphthalene precursor using the focused electron beam induced deposition technique. This allows the deposition of a carbon top‐contact electrode with well‐defined shape, thickness, and precise positioning on the film with nm resolution. These results represent a substantial step toward the realization of integrated molecular electronic devices based on monolayers and carbon electrodes.