Local Dynamic Stability Assessment of Motion Impaired Elderly Using Electronic Textile Pants

A clear association has been demonstrated between gait stability and falls in the elderly. Integration of wearable computing and human dynamic stability measures into home automation systems may help differentiate fall-prone individuals in a residential environment. The objective of the current study was to evaluate the capability of a pair of electronic textile (e-textile) pants system to assess local dynamic stability and to differentiate motion-impaired elderly from their healthy counterparts. A pair of e-textile pants comprised of numerous e-TAGs at locations corresponding to lower extremity joints was developed to collect acceleration, angular velocity and piezoelectric data. Four motion-impaired elderly together with nine healthy individuals (both young and old) participated in treadmill walking with a motion capture system simultaneously collecting kinematic data. Local dynamic stability, characterized by maximum Lyapunov exponent, was computed based on vertical acceleration and angular velocity at lower extremity joints for the measurements from both e-textile and motion capture systems. Results indicated that the motion-impaired elderly had significantly higher maximum Lyapunov exponents (computed from vertical acceleration data) than healthy individuals at the right ankle and hip joints. In addition, maximum Lyapunov exponents assessed by the motion capture system were found to be significantly higher than those assessed by the e-textile system. Despite the difference between these measurement techniques, attaching accelerometers at the ankle and hip joints was shown to be an effective sensor configuration. It was concluded that the e-textile pants system, via dynamic stability assessment, has the potential to identify motion-impaired elderly.     

Fabrication of planar cobalt electrodes separated by a sub-10nm gap using high resolution electron beam lithography with negative PMMA

We present a fabrication process of cobalt nanoelectrodes compatible with spin-dependent transport measurements through a few or a single nano-object. It consists in etching a cobalt thin layer into pairs of planar nanoelectrodes separated by a nanometric gap using a negative Poly-MethylMethAcrylate (PMMA) mask patterned by high resolution electron beam lithography (HREBL). The irradiation parameters of 200keV HREBL on PMMA have been investigated using atomic force microscopy (AFM) to define accurately the PMMA transformation from positive to negative tone. The influence of the electron dose and the designed gap on the final gap between electrodes is presented. This complete study proves that PMMA can be used as a HREBL negative resist to fabricate nanoelectrodes separated by a controlled and reproducible gap ranging from 5nm to several tens of nanometers.     

tweezercalib 2.0: Faster version of MatLab package for precise calibration of optical tweezers

We present a vectorized version of the MatLab (MathWorks Inc.) package tweezercalib for calibration of optical tweezers with precision. The calibration is based on the power spectrum of the Brownian motion of a dielectric bead trapped in the tweezers. Precision is achieved by accounting for a number of factors that affect this power spectrum, as described in vs. 1 of the package [I.M. Toli?-Nørrelykke, K. Berg-Sørensen, H. Flyvbjerg, Matlab program for precision calibration of optical tweezers, Comput. Phys. Comm. 159 (2004) 225-240]. The graphical user interface allows the user to include or leave out each of these factors. Several “health tests” are applied to the experimental data during calibration, and test results are displayed graphically. Thus, the user can easily see whether the data comply with the theory used for their interpretation. Final calibration results are given with statistical errors and covariance matrix.

New version program summary

Title of program: tweezercalibCatalogue identifier: ADTV_v2_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADTV_v2_0Program obtainable from: CPC Program Library, Queen's University of Belfast, N. IrelandReference in CPC to previous version: I.M. Toli?-Nørrelykke, K. Berg-Sørensen, H. Flyvbjerg, Comput. Phys. Comm. 159 (2004) 225Catalogue identifier of previous version: ADTVDoes the new version supersede the original program: YesComputer for which the program is designed and others on which it has been tested: General computer running MatLab (Mathworks Inc.)Operating systems under with the program has been tested: Windows2000, Windows-XP, LinuxProgramming language used: MatLab (Mathworks Inc.), standard licenseMemory required to execute with typical data: Of order four times the size of the data fileHigh speed storage required: noneNo. of lines in distributed program, including test data, etc.: 135 989No. of bytes in distributed program, including test data, etc.: 1 527 611Distribution format: tar. gzNature of physical problem: Calibrate optical tweezers with precision by fitting theory to experimental power spectrum of position of bead doing Brownian motion in incompressible fluid, possibly near microscope cover slip, while trapped in optical tweezers. Thereby determine spring constant of optical trap and conversion factor for arbitrary-units-to-nanometers for detection system.Method of solution: Elimination of cross-talk between quadrant photo-diode's output channels for positions (optional). Check that distribution of recorded positions agrees with Boltzmann distribution of bead in harmonic trap. Data compression and noise reduction by blocking method applied to power spectrum. Full accounting for hydrodynamic effects: Frequency-dependent drag force and interaction with nearby cover slip (optional). Full accounting for electronic filters (optional), for “virtual filtering” caused by detection system (optional). Full accounting for aliasing caused by finite sampling rate (optional). Standard non-linear least-squares fitting. Statistical support for fit is given, with several plots facilitating inspection of consistency and quality of data and fit.Summary of revisions: A faster fitting routine, adapted from [J. Nocedal, Y.x. Yuan, Combining trust region and line search techniques, Technical Report OTC 98/04, Optimization Technology Center, 1998; W.H. Press, B.P. Flannery, S.A. Teukolsky, W.T. Vetterling, Numerical Recipes. The Art of Scientific Computing, Cambridge University Press, Cambridge, 1986], is applied. It uses fewer function evaluations, and the remaining function evaluations have been vectorized. Calls to routines in Toolboxes not included with a standard MatLab license have been replaced by calls to routines that are included in the present package. Fitting parameters are rescaled to ensure that they are all of roughly the same size (of order 1) while being fitted. Generally, the program package has been updated to comply with MatLab, vs. 7.0, and optimized for speed.Restrictions on the complexity of the problem: Data should be positions of bead doing Brownian motion while held by optical tweezers. For high precision in final results, data should be time series measured over a long time, with sufficiently high experimental sampling rate: The sampling rate should be well above the characteristic frequency of the trap, the so-called corner frequency. Thus, the sampling frequency should typically be larger than 10 kHz. The Fast Fourier Transform used works optimally when the time series contain n² data points, and long measurement time is obtained with n>12-15. Finally, the optics should be set to ensure a harmonic trapping potential in the range of positions visited by the bead. The fitting procedure checks for harmonic potential.Typical running time: SecondsUnusual features of the program: NoneReferences: The theoretical underpinnings for the procedure are found in [K. Berg-Sørensen, H. Flyvbjerg, Power spectrum analysis for optical tweezers, Rev. Sci. Ins. 75 (2004) 594-612].     

Hydration of tricalcium germanate

The hydration characteristics of tricalcium germanate were examined. Kinetics of tricalcium germanate hydration, and hydration product morphologies and compositions were determined at 5 °C intervals between 5 and 70 °C. Complete hydration was rapidly achieved, X-ray diffraction indicated that tricalcium germanate reacted completely within 2 h at all the temperatures investigated. However, a constant value for an Arrhenius activation energy could not be determined. At hydration temperatures above 45 °C a small heat peak, which preceded the main calorimetric peak, appeared in the calorimetric curves. Calcium hydroxide was rarely observed by SEM for hydration at temperatures below 45 °C. Dense regions of calcium hydroxide were readily observed for hydration above this temperature. In contrast to the hydration of tricalcium silicate, an induction period was not observed nor was an extended period of diffusionally controlled reaction. Calcium germanate hydrate was fibrous with the fibre thickness exhibiting a temperature dependence. Hydration product compositions were determined by thermal gravimetry. Expressing the composition of calcium germanate hydrate as (CaO)_3–x GeO₂·nH₂O, the value of 3–x decreases from 1.68 to 1.59 with increasing temperature from 5–70 °C. The values obtained forn varied inconsistently between 2.4 and 3.3. The unit cell of the calcium germanate hydrate was determined to be monoclinic. Cell parameters werea=1.851,b=1.147,c=0.531 nm and =98.10 °.     

Approximating total citation counts from first author counts and from total papers

This paper is an attempt to improve on the approximation. First author citations (C_f)≈Total citations (C_t) of an author's publications without the work of making the complete citation count under the author and all co-author names. Using the bibliographies of all faculty from each of four large departments: Physics, Chemistry, Materials Sciences, and Biosciences, in the same university, both first author and complete citation counts were made, care being taken to avoid the most common errors in such counts. It is shown that the function C_f·T/F (where T and F are the total number of papers and F those with subject author's name first) correlates strongly (>90%) with C_t. We find also that C_t correlates strongly with T. The data also may be used as one more line of evidence to obtain normalizing ratios for possible comparisons of productivityacross different disciplinary universes. A very tentative ratio from different studies would be 8 (Chem.)=4 (Physics)=2.5 (Mat. Sci.)=2 (Mathematics)=4.5 (Biophysics-Biochemistry).     

Efficient matching of nonrectangular shapes

Most known two-dimensional matching algorithms have a rectangular text (image) and rectangular pattern (template) as their input. These matching algorithms perform a row by row analysis followed by some column processing. These techniques are only efficient if all the rows are of equal length, hence the necessity for rectangular patterns.We present a novel method for analysing patterns with rows of different lengths. This enables finding all occurrences of a nonrectangular figure of heightm in ann×n text in time . We make use of thesmaller matching problem.The smaller matching problem is that of finding all appearances of a numerical one dimensional pattern in a numerical one-dimensional text, where every element of the pattern is no greater than the corresponding text element.Partially supported by NSF grant CCR-88-03641 and a University of Maryland full year research award.Supported by a University of Maryland Graduate Fellowship, an ACM Samuel M. Alexander Fellowship and NSF grant CCR-88-03641.     

Producing persistent, high-current, high-duty-factor H- beams for routine 1 MW operation of Spallation Neutron Source (invited)

Since 2009, the Spallation Neutron Source (SNS) has been producing neutrons with ion beam powers near 1 MW, which requires the extraction of ～50 mA H(-) ions from the ion source with a ～5% duty factor. The 50 mA are achieved after an initial dose of ～3 mg of Cs and heating the Cs collar to ～170 °C. The 50 mA normally persist for the entire 4-week source service cycles. Fundamental processes are reviewed to elucidate the persistence of the SNS H(-) beams without a steady feed of Cs and why the Cs collar temperature may have to be kept near 170 °C.     

Soft computing-based approaches to predict energy consumption and stability margin of six-legged robots moving on gradient terrains

Soft computing-based approaches have been developed to predict specific energy consumption and stability margin of a six-legged robot ascending and descending some gradient terrains. Three different neuro-fuzzy and one neural network-based approaches have been developed. The performances of these approaches are compared among themselves, through computer simulations. Genetic algorithm-tuned multiple adaptive neuro-fuzzy inference system is found to perform better than other three approaches for predicting both the outputs. This could be due to a more exhaustive search carried out by the genetic algorithm in comparison with back-propagation algorithm and the use of two separate adaptive neuro-fuzzy inference systems for two different outputs. A designer may use the developed soft computing-based approaches in order to predict specific energy consumption and stability margin of the robot for a set of input parameters, beforehand.     

The effect of antioxidants on the production, of volatile nitrosamines during the frying of bacon

Summary In model system studies simulating the frying of bacon a considerable variation in the production of N-nitrosopyrrolidine (NOPyr) has been observed, as occurs in sliced bacon fried conventionally. The inclusion of ascorbate or erythorbate (isoascorbate) has led consistently to a fall in or an elimination of NOPyr production up to an addition of 300 ppm (1,5 mM). Above this concentration of ascorbate, the elimination of NOPyr formation persisted in some instances but in others an increased production of the nitrosamine occurred. Using-tocopherol, a fall of NOPyr production during the simulated frying of bacon was obtained with increase of concentration of the antioxidant, there being a consistent elimination of the volatile nitrosamine following an addition of 500 ppm (1.16 mM). Whilst ascorbyl palmitate had a similar action in reducing or eliminating NOPyr production, no synergistic effect between it and a-tocopherol was noted in an experiment combining the two antioxidants. When bacon was fried in fat containing 400 or 800 ppm-tocopherol, the total production of NOPyr and DMN in the fried bacon, cooked out fat and condensate was markedly reduced but not completely eliminated as in the model system studies. Similarly, the curing of bacon with a brine containing a mixture of-tocopherol, ascorbyl palmitate and citric acid has led to considerable reductions in NOPyr and DMN output on frying when the combined concentrations of the two anti-oxidants were calculated to be 800 ppm.

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Der Einfluß von Antioxydantien auf die Entwicklung flüchtiger Nitrosamine während des Bratens von Speck

Zusammenfassung Bei Untersuchungen in Modell-Systemen, in denen das Braten von Speck simuliert wurde, stellte man eine nennenswerte Variation in der Entstehung von N-Nitrosopyrrolidin (NOPyr) fest, wie sie auch bei konventionell gebratenem Scheibenspeck auftritt. Der Zusatz von Ascorbat oder Isoascorbat hat bei einem Zusatz bis zu 300 ppm (1,5 mmol) regelmäßig zur Abnahme der NOPyr-Produktion geführt. Bei größerer Ascorbatkonzentration nahm die NOPyr-Bildung in einigen Fällen ab, in anderen setzte dagegen eine erhöhte Nitrosaminbildung ein. Bei Anwendung von-Tokopherol wurde eine Abnahme in der NOPyr-Bildung während des simulierten Bratens von Speck bei zunehmender Antioxydantien-Konzentration erreicht, wobei ein gleichbleibendes Verschwinden des flüchtigen Nitrosamins eine Folge des Zusatzes von 500 ppm (1,16 mmol) war. Während Ascorbylpalmitat eine ähnliche Wirkung in der Reduzierung der NOPyr-Bildung hatte, konnte bei einem Experiment, bei dem die beiden Antioxydantien zugegen waren, keine synergistische Wirkung festgestellt werden. Wenn Speck in 400 oder 800 ppm-Tokopherol enthaltendem Fett gebraten wude, war die Gesamtbildung von NOPyr und DMN in dem gebratenen Speck, dem ausgekochten Fett und im Kondensat wesentlich reduziert, aber nicht wie bei den Modell-System-Versuchen vollständig eliminiert. Ähnlich führte auch das Pökeln von Speck in Lake, die eine Mischung von-Tokopherol, Ascorbylpalmitat und Citronensäure enthielt, zu wesentlicher Reduzierung in NOPyr- und DMN-Produktion beim Braten, wenn die Konzentration der beiden Antioxydatien zusammen auf 800 ppm berechnet wurden.