Test-retest reliability of cervicocephalic kinesthetic sensibility in three cardinal planes.

The test-retest reliability of both the head-to-neutral head position (NHP) and head-to-target repositioning tests in three cardinal planes has been examined in this study. Twenty young adults underwent both head repositioning tests and retests with 10 min rest intervals. Root mean square error (RMSE, total error), constant error (CE, directional bias), variable error (VE, variability), and standard error of measurement (SEM) were calculated from the position data recorded by an ultrasound-based motion analysis system. Intra-class correlation coefficients (ICC) were used to examine reliability. The results showed fair to excellent reliability of RMSE during head-to-NHP (ICC=0.45-0.80) and head-to-target tests (ICC=0.42-0.90), except during the head-to-NHP test (ICC=0.29) from a head extended position. Low reliability of VE associated with the neck motion toward left side bending indicated a direction-dependent effect. The SEM of RMSE (0.7-2.6 degrees), CE (0.3-4.0 degrees) and VE (0.4-1.5 degrees) indicated an acceptable range of error. The present study indicated acceptable and reliable RMSE measurements with a motion analysis system in healthy young adults. Furthermore, examining the CE and VE could contribute to the interpretation of whether the subject performed the reposition tests with directional bias and repositioning variability, respectively.

Stability of polyomavirus major capsid protein VP1 under denaturants guanidine hydrochloride and urea.

The guanidine hydrochloride (GdnHCl)- and urea-induced equilibrium denaturation of recombinant polyomavirus (Py) major capsid protein VP1 was studied by circular dichroism and fluorescence spectroscopy. Both secondary and tertiary structures of PyVP1 were shown to be disrupted in the presence of denaturants. Although the far-UV circular dichroism (CD) spectra of PyVP1 in the denaturants exhibit similar two-phase transition as those obtained from the fluorescence measurements, the unfolding of PyVP1 in GdnHCl was shown to be more complex than a similar two-state mechanism. The presence of unfolding intermediates is manifested by the noncoincidence of transitions when detected by different probes. The unfolding intermediate appeared to be stabilized by 1 M NaCl. Addition of Ca2+ and 2-mercaptoethanol does not show significant effect on the conformational stability of PyVP1. Unfolding of PyVP1 in GdnHCl was shown to be an irreversible process.

Automated learning for reducing the configuration of a feedforward neural network.

In this paper, we present two learning mechanisms for artificial neural networks (ANN's) that can be applied to solve classification problems with binary outputs. These mechanisms are used to reduce the number of hidden units of an ANN when trained by the cascade-correlation learning algorithm (CAS). Since CAS adds hidden units incrementally as learning proceeds, it is difficult to predict the number of hidden units required when convergence is reached. Further, learning must be restarted when the number of hidden units is larger than expected. Our key idea in this paper is to provide alternatives in the learning process and to select the best alternative dynamically based on run-time information obtained. Mixed-mode learning (MM), our first algorithm, provides alternative output matrices so that learning is extended to find one of the many one-to-many mappings instead of finding a unique one-to-one mapping. Since the objective of learning is relaxed by this transformation, the number of learning epochs can be reduced. This in turn leads to a smaller number of hidden units required for convergence. Population-based learning for ANN's (PLAN), our second algorithm, maintains alternative network configurations to select at run time promising networks to train based on error information obtained and time remaining. This dynamic scheduling avoids training possibly unpromising ANNs to completion before exploring new ones. We show the performance of these two mechanisms by applying them to solve the two-spiral problem, a two-region classification problem, and the Pima Indian diabetes diagnosis problem.

Simplification of fuzzy-neural systems using similarity analysis.

This paper presents a fuzzy neural network system (FNNS) for implementing fuzzy inference systems. In the FNNS, a fuzzy similarity measure for fuzzy rules is proposed to eliminate redundant fuzzy logical rules, so that the number of rules in the resulting fuzzy inference system will be reduced. Moreover, a fuzzy similarity measure for fuzzy sets that indicates the degree to which two fuzzy sets are equal is applied to combine similar input linguistic term nodes. Thus we obtain a method for reducing the complexity of a fuzzy neural network. We also design a new and efficient on-line initialization method for choosing the initial parameters of the FNNS. A computer simulation is presented to illustrate the performance and applicability of the proposed FNNS. The result indicates that the FNNS still has desirable performance under fewer fuzzy logical rules and adjustable parameters.

Quantitative feedback synthesis of sampled-data systems with time-delay by approximate Z-transform.

In this paper, the equivalent disturbance rejection (EDR) in QFT design methodology is proposed for dealing with sampled-data systems with time-delay. This EDR is mainly to overcome the non-minimum phase zero generated by the first order Pade' approximation of the time-delay factor. Due to plant parameter uncertainty, the analogue controller is to be designed so that the system response lies within permissible bounds. By approximate Z-transform, the analogue controller can be transformed directly into a digital one and then the analogue plant is transformed into the digital plant, with sampling time as a free parameter. By adjusting the sampling time, the uncertain sampled-data system can be stabilized. In comparison with other approaches, our design framework is much more systematic by using only algebraic manipulations and transparent enough to guide the designer to realize the physical controller for the plant with prescribed bounds on its parameters.

Baseline mean deviation and rates of visual field change in treated glaucoma patients.

PURPOSE: To evaluate the relationships between baseline visual field (VF) mean deviation (MD) and subsequent progression in treated glaucoma. METHODS: Records of patients seen in a glaucoma practice between 1999 and 2009 were reviewed. Patients with glaucomatous optic neuropathy, baseline VF damage, and ≥8 SITA-standard 24-2 VF were included. Patients were divided into tertiles based upon baseline MD. Automated pointwise linear regression determined global and localized rates (decibels (dB) per year) of change. Progression was defined when two or more adjacent test locations in the same hemifield showed a sensitivity decline at a rate of >1.0 dB per year, P<0.01. RESULTS: For mild, moderate, and severe groups, progression was noted in 29.5, 31.2, and 26.0% of eyes (P=0.50) and global rates of VF change of progressing eyes were -1.3±1.2, -1.01±0.7, and -0.9±0.5 dB/year (P=0.09, analysis of variance). Within these groups, intraocular pressure (IOP) in stable vs progressing eyes were 15.5±3.3 vs 17.0±3.1 (P<0.01), 15.4±3.3 vs 15.9±2.5 (P=0.28), and 14.0±2.8 vs 14.8±2.3 mm Hg (P=0.07). More glaucoma filtering surgeries were performed in eyes with worse MD. There was no significant difference between groups regarding their risk of progression in both univariate (P=0.50) and multivariate (P=0.26) analyses adjusting for differences in follow-up IOP. CONCLUSIONS: After correcting for differences in IOP in treated glaucoma patients, we did not find a relationship between the rate of VF change (dB per year) and the severity of the baseline VF MD. This finding may have been due to more aggressive IOP lowering in eyes with more severe disease. Eyes with lower IOP progressed less frequently across the spectrum of VF loss.

Cervicocephalic kinesthetic sensibility in young and middle-aged adults with or without a history of mild neck pain.

Previous research has shown that there is no significant relationship between the degree of structural degeneration of the cervical spine and neck pain. We therefore sought to investigate the potential role of sensory dysfunction in chronic neck pain. Cervicocephalic kinesthetic sensibility, expressed by how accurately an individual can reposition the head, was studied in three groups of individuals, a control group of 20 asymptomatic young adults and two groups of middle-aged adults (20 subjects in each group) with or without a history of mild neck pain. An ultrasound-based three-dimensional coordinate measuring system was used to measure the position of the head and to test the accuracy of repositioning. Constant error (indicating that the subject overshot or undershot the intended position) and root mean square errors (representing total errors of accuracy and variability) were measured during repositioning of the head to the neutral head position (Head-to-NHP) and repositioning of the head to the target (Head-to-Target) in three cardinal planes (sagittal, transverse, and frontal). Analysis of covariance (ANCOVA) was used to test the group effect, with age used as a covariate. The constant errors during repositioning from a flexed position and from an extended position to the NHP were significantly greater in the middle-aged subjects than in the control group (beta=0.30 and beta=0.60, respectively; P<0.05 for both). In addition, the root mean square errors during repositioning from a flexed or extended position to the NHP were greater in the middle-aged subjects than in the control group (beta=0.27 and beta=0.49, respectively; P<0.05 for both). The root mean square errors also increased during Head-to-Target in left rotation (beta=0.24;P<0.05), but there was no difference in the constant errors or root mean square errors during Head-to-NHP repositioning from other target positions (P>0.05). The results indicate that, after controlling for age as a covariate, there was no group effect. Thus, age appears to have a profound effect on an individual's ability to accurately reposition the head toward the neutral position in the sagittal plane and repositioning the head toward left rotation. A history of mild chronic neck pain alone had no significant effect on cervicocephalic kinesthetic sensibility.

Precision measurements of the optical attenuation profile along the propagation path in thin-film waveguides.

An experimental technique for precision measurements of the optical attenuation profile along a propagation path in thin-film waveguides is reported. The method involves a 100% outcoupling of guided light through immersion of the waveguide into a liquid with an index of refraction slightly higher than that of the film. The measurement is simple and nondestructive. The repeatability and accuracy of the measured attenuation per unit length is typically better than 5%, even with losses below 0.1 dB/cm and less than 1-cm-long guiding paths.

Conformational changes of polyomavirus major capsid protein VP1 in sodium dodecyl sulfate solution.

Conformations of polyomavirus (Py) major capsid protein VP1 were analyzed by circular dichroism (CD) and fluorescence spectroscopy in the presence of sodium dodecyl sulfate (SDS). Binding of PyVP1 to SDS induced marked conformational changes of PyVP1, which were reflected on the CD and fluorescence spectra. Abrupt changes in both optical properties occurred within the narrow ranges of SDS concentrations with the transition midpoints closely related to SDS micelle formation. Analysis of circular dichroism spectra showed that the contents of alpha-helices, beta-sheets, beta-turns and random coils in PyVP1 varied upon addition of SDS, demonstrating the exquisite sensitivity of the conformations of the protein to the environment. The interactions of PyVP1 with SDS were shown to be dependent on the ionic strength of the protein solution, suggesting that both hydrophobic and electrostatic forces contribute to the PyVP1-SDS complex formation. The SDS-induced conformational changes of PyVP1 appeared to be a two-stage process.

Circular dichroism and fluorescence studies of polyomavirus major capsid protein VP1.

The conformational changes of polymavirus (Py) major capsid protein VP1 in solution by the solution pH, addition of calcium, and ionic strength were examined by circular dichroism (CD) and fluorescence spectroscopy. Comparison of the predicted secondary structures of PyVP1 and simian virus (SV) 40 by the methods of Chou-Fasman, Garnier et al., and Yang method are presented. Hydropathicity, surface probability, and chain flexibility of PyVP1 were computer-analyzed by the methods of Kyte and Doolittle, Emini et al., and Karplus and Schulz, respectively. The CD measurements indicate that the secondary structure of PyVP1 is little dependent on its concentration, Ca2+ concentration, and ionic strength, but is strongly pH dependent. Fluorescence studies showed that emission spectra of PyVP1 are also pH-dependent. At extreme acidic and alkaline pH, the fluorescence intensity of PyVP1 is decreased and the emission maximum is red-shifted. The fluorescence of PyVP1 is quenched by the presence of CsCl, KI, and acrylamide. The analyses of the modified Stern-Volmer plots indicate that five of seven tryptophan residues in PyVP1 are located on the surface of the protein, among which two are accessible to Cs+ and the other three are accessible to I- . The two others are buried more deeply in the interior of the protein molecule.

Versatile stable isotope technique for the measurement of amino acids and keto acids: comparison with radioactive isotope and its use in measuring in vivo disposal rates.

Tracer methods using both carbon-13 and -14 have been utilized for determination of ovine fetal amino acid disposal and the results compared in seven animals. We infused [1-13C]leucine simultaneously with [1-14C]leucine into the fetal circulation of pregnant sheep chronically catheterized during late gestation. Radioactive and stable isotope enrichments of leucine (Leu) and stable isotope enrichments of ketoisocaproic acid (KIC) in the umbilical artery and vein and the maternal artery and uterine vein were measured. Stable isotope enrichments and concentrations of both Leu and KIC were determined from a single 0.2-ml sample by the use of internal standards and electron ionization GC/MS analysis after a simple isolation and derivatization procedure. The KIC/Leu enrichment ratio was measured for the first time in fetal arterial plasma and was 0.66 +/- 0.05 (SE). Fetal leucine disposal rate was 9.0 +/- 0.5 (SE) micron/min/kg. Disposal rates determined by stable isotopes were not different from those determined by radioactive isotopes. The GC/MS stable isotope method provided higher precision in both leucine concentration and enrichment measurements and has been shown to be a general method for the determination of concentration and isotopic enrichment of other amino acids and their corresponding keto acids. Furthermore, this method is ideally suited to clinical studies where large numbers of samples of rather small volume can easily be studied with a short turnaround time.

Leucine metabolism in chronically hypoglycemic hypoinsulinemic growth-restricted fetal sheep.

We measured leucine flux rates during infusions of L-[1-14C]- and L-[1-1C]leucine in fetal sheep exposed to maternal insulin-induced hypoglycemia over the last 8 wk (40%) of gestation to determine effects of chronic glucose deficiency and hypoglycemia on fetal leucine metabolism. Compared with control fetuses (C, n = 5), hypoglycemic fetuses (HG, n = 8) weighed less (C, 3.43 +/- 0.07 kg; HG, 2.32 +/- 0.24 kg), had lower plasma glucose (C, 1.04 +/- 0.02 mM; HG, 0.59 +/- 0.01 mM), insulin (C, 48 +/- 6 pM; HG, 12 +/- 6 pM), and leucine concentrations (C, 195.6 +/- 8.3 microM; HG, 140.8 +/- 15.0 microM), lower rates of net leucine uptake (C, 4.2 +/- 0.6 mumol.min-1.kg-1; HG, 2.1 +/- 0.4 mumol.min-1.kg-1) and leucine flux into protein accretion (C, 2.8 +/- 0.2 mumol.min-1.kg-1; HG, 0.6 +/- 0.1 mumol.min-1.kg-1), and an increased rate of leucine release from protein breakdown (C, 1.1 +/- 0.1 mumol.min-1.kg-1; HG, 3.3 +/- 0.2 mumol.min-1.kg-1) (P < 0.05 for all). Plasma leucine disposal, flux into protein synthesis, and oxidation were not different between groups. We conclude that adaptations of fetal leucine metabolism to long-term hypoglycemia and decreased glucose apply represent diminished leucine uptake and increased leucine release from protein breakdown, which are associated with decreased incorporation of leucine into protein accretion and a slower rate of fetal growth.