A method for computing the partial derivatives of experimental data

This article describes a procedure for obtaining the partial derivatives of experimental data that depend on two independent variables. The starting equation is an ill‐posed integral equation of the first kind. Tikhonov regularization is used to keep noise amplification under control. Implementation of the computation steps is described and the performance of the procedure is demonstrated by four practical examples. © 2010 American Institute of Chemical Engineers AIChE J, 2010     

The effects of morphine on the accumulation of homovanillic and 5-hydroxyindoleacetic acids in the choroid plexus of rats

1 Choroid plexus obtained from the lateral ventricles of the rat actively accumulated homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA). 2 Morphine 5 X 10(-6) M to 5 X 10(-4)M potentiated 5-HIAA accumulation but did not affect HVA accumulation. Levorphanol and dextorphan had little effect. 3 Naloxone at high concentrations inhibited both HVA and 5-HIAA accumulation. 4 Glutamic acid, glycine, and arginine also decreased 5-HIAA accumulation, but lysine, tryptophan, and aspartic acid had no effect. 5 Probenecid, naloxone, arginine, glycine, and tryptophan blocked the increase of 5-HIAA accumulation induced by morphine. 6 Acute or chronic morphine treatment did not increase the accumulation of 5-HIAA. 7 These results suggest that the increase of 5-HIAA or HVA in brain by morphine is not due to the inhibition of the elimination of these metabolites from the choroid plexus.     

Admittance tympanometry in otosclerotic ears

Twenty-eight surgically confirmed otosclerotic ears were evaluated to determine whether tympanometric admittance measurements could differentiate otosclerosis from a normal population. Subjects were tympanometrically measured at test conditions B220, B660, G220 and G660 Hz. When comparing mean curve peak amplitude to normative standards, 20 ears showed significantly low admittance tympanograms. Further investigation revealed no significant differences in curve width or pressure of the curve peak. Of the remaining eight otosclerotic ears, all produced diphasic "W"-notched tympanometric configurations. Diagnostic implications and physiological hypothesis are discussed.     

Obtaining model‐independent growth rates from experimental data of dry thermal oxidation of silicon

Empirical time‐oxide layer thickness data of dry thermal oxidation of silicon were converted numerically into instantaneous growth rates by Tikhonov regularization. These growth rates are independent of any assumed kinetics of oxidation or functional form of the original data and can, therefore, be used in model testing of this important industrial process. A number of numerical issues in the Tikhonov regularization computation, for example, the expected monotonic decrease in growth rate with time and the large time span of some of the datasets, are addressed. Numerical results indicate that kinetic data presented in the form of growth rate‐oxide layer thickness plots are more sensitive than the traditional time‐oxide thickness plots for use in model testing and for parameter determination. The advantages of this new approach are demonstrated by three case studies covering the complete oxide thickness spectrum of interest to the microelectronic industry. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1810–1820, 2014     

Short-term exercise enhances insulin-stimulated GLUT-4 translocation and glucose transport in adipose cells

This investigation examined the effects of short-term exercise training on insulin-stimulated GLUT-4 glucose transporter translocation and glucose transport activity in rat adipose cells. Male Wistar rats were randomly assigned to a sedentary (Sed) or swim training group (Sw, 4 days; final 3 days: 2 x 3 h/day). Adipose cell size decreased significantly but minimally (approximately 20%), whereas total GLUT-4 increased by 30% in Sw vs. Sed rats. Basal 3-O-methyl-D-[14C]glucose transport was reduced by 62%, whereas maximally insulin-stimulated (MIS) glucose transport was increased by 36% in Sw vs. Sed rats. MIS cell surface GLUT-4 photolabeling was 44% higher in the Sw vs. Sed animals, similar to the increases observed in MIS glucose transport activity and total GLUT-4. These results suggest that increases in total GLUT-4 and GLUT-4 translocation to the cell surface contribute to the increase in MIS glucose transport with short-term exercise training. In addition, the results suggest that the exercise training-induced adaptations in glucose transport occur more rapidly than previously thought and with minimal changes in adipose cell size.     

Crucial web usability factors of 36 industries for students: a large-scale empirical study

The study identifies and prioritizes the crucial Web Usability Factors (WUFs) for websites from 36 industries. 400 respondents participated in the web evaluation and more than 12,000 data points were collected and analyzed using Multiple Linear Regression. Seven WUFs were tested, i.e. Use of Color and Font, Use of Graphics and Multimedia, Clarity of Goals in Website, Trustworthiness of Website, Interactivity of Website, Ease of Web Navigation, and Downloading Speed of Website. Results reveal that every industry has a different set of crucial WUFs. The research compared and discussed its results with previous studies such as Agarwal and Venkatesh (Inf. Syst. Res. 13:168–186, 2002). Moreover, students’ preference for Web usability was compared with that of general Internet users. The study provides a simple method to measure web usability and to determine which WUFs are important for a specific industry with consideration of the users’ role. Practitioners can use the results as a guide to design usable websites for specific industry. This study is the first that comprehensively examines the WUFs of students by employing a very large sample size across various industries, thus yielding more specific and meaningful results.     

DUCTILE-REGIME MACHINING OF PARTICLE-REINFORCED METAL MATRIX COMPOSITES

ABSTRACT

This paper presents research results on ultraprecision machining of metal matrix composite (MMC) composed of aluminum matrix and either SiC or A1₂ 0₃ particles. Ductile-regime machining of both SiC and aluminum was evaluated to improve the surface integrity of the composite. Both polycrystal-line diamond (PCD) and single crystalline diamond (SCD) tools were used to ultraprecision machine the composites at a depth of cut ranging from 0 to 1μm using a taper cut. The feedrate was normalized to the tool nose radius. A model is proposed to calculate the critical depth of cut for MMCs reinforced with either A1₂0₃ or SiC. The critical depths of cut were found to be 1 p.m and 0.2 u.m for MMCs reinforced with A1₂ 0 or SiC₃, respectively. Both depth of cut and crystallographic direction of the ceramic particles are the sufficient conditions for ductile-regime machining. Although both tools produce similar surface finish, a SCD tool removed the MMC as chips while a PCD tool simply smeared the surface. A diffusion-abrasion mechanism was suspected to cause the surprising wear of the SCD tools when machining the aluminum/SiC composite.     

Conditioning leisure time physical activity and cardiorespiratory fitness in sociodemographic groups of middle-ages men in eastern Finland

In the decade of the 1990's the human aspect has once again taken center stage in the design and operation of commercial aircraft. As occupation health and safety has gained importance in society in general, it has gained even more importance in the design an operation of commercial aircraft. In aircraft design today, the man-machine interface is considered in every task of the human workload. The discipline of ergonomics truly impacts each phase of product or tool design. At IPTN, the ergonomics effort is principally being applied to the design of the cockpit, cabin and cargo compartment of the N250. The ergonomists at IPTN are keenly aware that there would be a conflict between the user and his working environment without proper attention to the human considerations in the design is left for ergonomists and innovative programs like IPTN's participatory approach, to ensure that the human aspect is optimized in the man-machine interface.     

Factors regulating insulin-like growth factor-binding protein-3 binding, processing, and potentiation of insulin-like growth factor action

In this study, we investigated the effects of various biochemical and pharmacological agents on insulin-like growth factor (IGF)-binding protein-3 (IGFBP-3) cell binding and action in cultured bovine fibroblasts. When cells were preincubated for 48 h with 50 nM recombinant human (rh) IGFBP-3, IGF-I-stimulated [3H]aminoisobutyric acid ([125H]AIB) uptake was enhanced 2- to 3-fold. The addition of cytoskeletal disrupting agents during the preincubation with rhIGFBP-3 did not affect IGFBP-3 potentiation of IGF-I action, nor did a variety of serine, aspartate, and metalloproteinase inhibitors. On the other hand, ammonium chloride and chloroquine, weak bases that neutralize the pH of acidic cell compartments, blocked IGFBP-3 potentiation of IGF-I-stimulated [3H]AIB uptake. Chloroquine and ammonium chloride had no effect alone and did not inhibit IGF-I receptor binding or action in the absence of rhIGFBP-3. Bafilomycin A, a specific inhibitor of ATP-dependent hydrogen ion pumps, also inhibited IGFBP-3 potentiation of IGF-I-stimulated [3H]AIB uptake. Competitive [125I]IGF-I binding and affinity cross-linking experiments suggested structure/function changes in cell-bound IGFBP-3 that were altered in the presence of chloroquine and bafilomycin. Heparin markedly decreased initial IGFBP-3 cell adherence, but could not promote dissociation of IGFBP-3 from cells after the 48-h preincubation. Moreover, heparin did not inhibit IGFBP-3 potentiation of IGF-I action. In summary, these data indicate that IGFBP-3 undergoes specific pH-dependent structural and/or environmental modifications that mediate the enhancing effect of IGFBP-3 on IGF-I action in bovine fibroblasts. They also suggest that IGFBP-3 binding to heparin-like molecules on the cell surface is not directly involved in this process.     

Atrioventricular junctional tissue. Discrepancy between histological and electrophysiological characteristics

BACKGROUND: Previous work has demonstrated that cells with AV nodal-type action potentials are not confined to Koch's triangle but may extend along the AV orifices. The aim of this study was to examine the histological and electrophysiological characteristics of this tissue. METHODS AND RESULTS: Studies were performed in isolated, blood-perfused dog and pig hearts. Microelectrode recordings revealed cells with nodal-type action potentials around the tricuspid and mitral valve rings. These cells were found within 1 to 2 mm of the valve annuli. A zone of cells with intermediate action potentials, approximately 1 cm wide, separated cells with nodal-type action potentials from cells with atrial-type action potentials in the body of the atria. In cells with nodal-type action potentials, adenosine caused a reduction in action potential amplitude (49 +/- 2 versus 33 +/- 2 mV, mean +/- SE; P < .001), upstroke velocity (2.5 +/- 0.2 versus 2.0 +/- 0.2 V/s, P < .05), and duration (150 +/- 4 versus 96 +/- 8 ms, P < .001). The light microscopic appearance of AV junctional cells was similar to that of myocytes in the body of the atrium. A polyclonal antibody raised against connexin-43 bound to atrial and ventricular tissue but not to the AV junctional tissue or AV nodal region. The absence of connexin-43 correlated with the sites of cells with nodal-like action potentials. With pacing techniques, the AV junctional tissue in the region of the posterior AV nodal approaches could be electrically dissociated from atrial, AV nodal, and ventricular tissue. AV nodal echoes were induced with ventricular pacing in three dog hearts. In each case, retrograde conduction was through the slow pathway, and anterograde conduction was through the fast pathway. During echoes, activation of AV junctional cells preceded atrial activation during retrograde slow pathway conduction, but these cells were not activated during anterograde fast pathway conduction. CONCLUSIONS: AV junctional cells around both annuli are histologically similar to atrial cells but resemble nodal cells in their cellular electrophysiology, response to adenosine, and lack of connexin-43. The light microscopic appearance of AV junctional cells is a poor guide to their action potential characteristics. The AV junctional cells in the posterior AV nodal approaches appear to participate in slow pathway conduction. These cells may be the substrate of the slow "AV nodal" pathway.