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131.
M. Asif Khawaja Fang Chen Nadine Marcus 《International journal of human-computer interaction》2014,30(5):343-368
An intelligent adaptable system, aware of a user’s experienced cognitive load, may help improve performance in complex, time-critical situations by dynamically deploying more appropriate output strategies to reduce cognitive load. However, measuring a user’s cognitive load robustly, in real-time is not a trivial task. Many research studies have attempted to assess users’ cognitive load using different measurements, but these are often unsuitable for deployment in real-life applications due to high intrusiveness. Relatively novel linguistic behavioral features as potential indices of user’s cognitive load is proposed. These features may be collected implicitly and nonintrusively supporting real-time assessment of users’ cognitive load and accordingly allowing adaptive usability evaluation and interaction. Results from a laboratory experiment show significantly different linguistic patterns under different task complexities and cognitive load levels. Implications of the research for adaptive interaction are also discussed, that is, how the cognitive load measurement-based approach could be used for user interface evaluation and interaction design improvement. 相似文献
132.
In this paper, we present an invariant‐set‐based method for actuator and sensor fault detection and isolation in Lure systems. The Lure plant is controlled by an observer‐based feedback tracking controller, designed for the nominal (fault‐free) system. Suitable residual signals are constructed from measurable system outputs and estimates associated with the nominal observer. Faults are diagnosed by online contrasting the residual signal trajectories against sets of values that the residuals are shown to attain under healthy or faulty operation. These values are obtained via set‐invariance analysis of the system closed‐loop trajectories. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
133.
Chamorro G Salazar M Araújo KG dos Santos CP Ceballos G Castillo LF 《Archivos latinoamericanos de nutrición》2002,52(3):232-240
Spirulina (Arthrospira), a filamentous, unicellular alga, is a cyanobacterium grown in certain countries as food for human and animal consumption. It is also used to derive additives in pharmaceuticals and foods. This alga is a rich source of proteins, vitamins, amino acids, minerals, and other nutrients. Its main use, therefore, is as a food supplement. Over the last few years, however, it has been found to have many additional pharmacological properties. Thus, it has been experimentally proven, in vivo and in vitro that it is effective to treat certain allergies, anemia, cancer, hepatotoxicity, viral and cardiovascular diseases, hyperglycemia, hyperlipidemia, immunodeficiency, and inflammatory processes, among others. Several of these activities are attributed to Spirulina itself or to some of its components including fatty acids omega-3 or omega-6, beta-carotene, alpha-tocopherol, phycocyanin, phenol compounds, and a recently isolated complex, Ca-Spirulan (Ca-SP). This paper aims to update and critically review the results published over the last few years with regards to these properties. The conclusion is that even if this cyanobacterium has been one of the most extensively studied from the chemical, pharmacological and toxicological points of view, it is still necessary to expand the research in order to have more consistent data for its possible use in human beings. 相似文献
134.
The electron spin resonance spectra (ESR) of complexes of copper with fibrous cotton cellulose under various experimental conditions were determined. Cupric ions dissolved in solutions of strong bases, such as concentrated ammonium hydroxide, sodium hydroxide, and potassium hydroxide, formed complexes with fibrous cotton cellulose. These complexes had paramagnetic resonance properties and generated characteristic ESR spectra. Cupric ions dissolved in solutions of highly ionized neutral salts, such as sodium chloride, formed complexes with cellulose. These complexes also generated the same characteristic ESR spectra as the complexes formed in solutions of strong base. The reaction between cupric ions and cellulose was evidently very rapid and reversible. When the concentration of ammonia was decreased in, or ammonia was removed from, the cupric ion–ammonium hydroxide–cellulose complexes, the paramagnetic resonance properties of the complex were decreased or lost. Similar results were received when potassium hydroxide was removed from the complexes. The compositions of the complexes evidently are variable, that is, under different experimental conditions the relative intensities of the lines of the ESR spectra of the complexes varied, although the hyperfine splittings of the lines were constant. It was concluded that reactions of cupric ions to form complexes with adjacent hydroxyl groups on the cellulose molecule depended on an optimum spatial arrangement of the hydroxyl groups, that is, distance between the groups. Evidently, wetting of cotton cellulosic fibers with solutions of strong bases or neutral salt allowed rotation about the C2–C3 bond to yield this optimum arrangement. When the base or salt was removed, rotation occurred to give less favorable positions of the hydroxyl groups for complexing with cupric ions. 相似文献
135.
Daniel Escolar María R. Haro Jesús Ayuso 《Journal of the American Oil Chemists' Society》2002,79(8):769-774
Four polynomial expressions are obtained that provide a good approximation and an easy, rapid calculation of the chromatic
coordinates and the chroma—L
*, a
*, b
*, and C—for the illuminant C and the standard observer, for a virgin or extra virgin olive oil; absorbance is measured at only 480
and 670 nm. These are as follows: L
*=0.556458(A480)2−2.51145A480+0.55504(A670)2−8.53016A670+98.4089; a
*=0.177372(A480)2+2.1363A480+1.43254(A670)2−0.789231A670−13.9246; b
*=−16.0277(A480)2+79.8932A480−5.06558(A670)2+3.36169A670+31.9405; C=−15.8439(A480)2+78.9312A480−5.26784(A670)2+3.56917A670+33.3927. These give acceptable results, making the method a practical alternative to the extremely laborious Commission Internationale
d’Eclairage (CIE) L
*
a
*
b
*
system, by which 391 absorbance values must be measured individually, nanometer by nanometer, before applying more complex
equations. The validity of the proposed method has been confirmed by comparison, using a set of 20 sample oils different from
the set of 25 oils used to generate the order of the equations. The variations between the values provided by the proposed
and standard methods, respectively, had a mean of 0.00 for each of the chromatic variables—L
*
, a
*
, b
*
, and C; SD were moderate (0.71, 0.52, 1.22, and 1.22, respectively); the root mean square and the R
2-terms also confirmed the validity of the method. 相似文献
136.
Estrada H Gamboa Mdel M Arias ML Chaves C 《Archivos latinoamericanos de nutrición》2005,55(2):167-171
The evaluation of the microbiological charge present in Costa Rican samples as the evaluation of its antimicrobial activity over different microorganisms, including those associated to wound infections, will allow to emit criteria referred to its use in therapeutic treatments, specially as alternative therapy for cases involving antibiotic resistant bacteria. The microbiological charge of 25 honey samples, acquired in Costa Rican markets was evaluated through several indicators including total plate aerobic count, total plate anaerobic count, total aerobic spore count, total anaerobic spore count and molds and yeast count. Also, samples were inoculated in tubes with chopped meat media and plated in egg yolk agar in order to determine the presence of Clostridium botulinum. For the antimicrobial activity evaluation, the diffusion method in Muller Hinton agar was performed, testing different honey concentrations (100, 75, 50, 25, 12,5 and 6,25 % v/v) against Staphylococcus aureus (ATCC 25923), Staphylococcus epidermidis (UCR 2902), Pseudomonas aeruginosa (ATCC 9027), Escherichia coli (ATCC25922), Salmonella enteritidis (ATCC 13076), Listeria monocytogenes (ATCC 19116) and Aspergillus niger. The results obtained for the microbiological characterization of honey show that 91% of samples had counts equal or lower than 1,0 x 10(1) CFU/g. No positive result was obtained for the isolation of C. botulinum. 24 of the samples analyzed inhibited the growth of S. aureus even in a 25% v/v concentration, nevertheless, A. niger was no inhibited by any of the samples tested. 相似文献
137.
Charge transfer complexes possessing a … DADA … structure with both the donor, D, and acceptor, A, being S = 1/2 radicals may exhibit cooperative magnetic phenomena. The complex [Fe(C5Me5)2]+·[TCNQ]−· exhibits metamagnetic behavior. The similarly structured [TCNE]−· and [C4(CN)6]−· complexes are ferromagnets, whereas the [DDQ]−· salt is a paramagnet. The high temperature magnetic susceptibility obeys the Curie-Weiss expression with θ = + 30, + 30, and + 3 for the [TCNE]−·, [C4(CN)6]−·, and [TCNQ]−· salts, respectively. The ferromagnetic [TCNE]−· salt exhibits zero field Zeeman split 57Fe Mossbauer spectra with an internal field of 425.6 kOe at 4.23 K. After reviewing the current papers discussing ferromagnetism in molecular (organic) compounds, a qualitative model consistent with the necessary bulk spin alignment required for a ferromagnet is presented. 相似文献
138.
Suárez T Torrealba M Villegas N Osorio C García-Casal MN 《Archivos latinoamericanos de nutrición》2005,55(2):118-123
Since in recent years for certain age groups, the main cause of anemia is not iron deficiency, we intended to study the effect of iron, folic acid and vitamin B12 deficiencies on anemia prevalence in adolescents from Venezuela. One hundred adolescents aged between 12 and 19 years participated in the study. Each subject was interviewed about antecedents and habits and a physical examination and a 24-hour food recall questionnaire were performed. From a blood sample, hemoglobin and hematocrit concentrations were determined and serum was separated for quantification of ferritin, folic acid and vitamin B12 concentrations. Prevalence of anemia was 78% and for iron, folic acid and vitamin B12 deficiencies were 34.66, 90.9 and 18.18%, respectively. From anemic cases, 35.89% presented iron deficiency, while 91.02% presented folic acid deficiency. Only 19.23% of adolescents with anemia presented also vitamin B12 deficiency, but all the cases with vitamin B12 deficiency, were anemic. Simultaneous iron and folic acid deficiencies affected 30.76% of anemic cases. The high prevalence of deficiencies found in this work could be explained by insufficient intake and inadequate food habits. The prevalence of anemia was associated to folic acid deficiency rather than to iron deficiency, due to the high prevalence of folic acid deficiency. The high prevalence of nutritional deficiencies found in this work, especially regarding folic acid deficiency, require immediate interventions. 相似文献
139.
Oxidation Behavior and Flexural Strength of Aluminum Nitride Exposed to Air at Elevated Temperatures 总被引:1,自引:0,他引:1
The oxidation behavior of a sintered aluminum nitride containing 3 wt% Y2 O3 as a sintering aid was investigated. Samples were exposed to air at elevated temperatures for times up to 100 h. The weights of the samples were continuously monitored during exposure at various temperatures and humidity levels. The effects of oxidation on room-temperature flexural strength were also determined, and correlated to the observed weight changes of the samples. At temperatures 1200°C, linear weight gains were observed. However, at temperatures above 1200°C, the weight gains became parabolic with respect to exposure time. The oxidation rates were significantly increased by water vapor in the air. The oxidation products were found by X-ray analysis to be a mixture of Al2 O3 and 5A12 O3 ·3Y2 O3 . The oxide layer formed on the surface was severely cracked because of the thermal expansion mismatch between the oxide layer and the substrate. The cracks initiated in the oxide layer and propagated into the substrate, resulting in severe reduction in the room-temperature flexural strength of the material. When exposed to ambient air for more than 50 h at temperatures greater than 1100°C, the strengths of the samples decreased to less than half that of the as-received material. 相似文献
140.
Jett C. Arthur Jr. 《Journal of the American Oil Chemists' Society》1971,48(6):271-272
Surface active agents are used in the textile industry during the processing of fibers into yarns and fabrics, the finishing
of leather products and during the removal of soil from textile products by laundering or dry cleaning. In these introductory
remarks to the symposium, attention is directed to the phenomena occurring at solid-liquid interfaces during these processes.
The properties of the surface active agents and the solvents used, the surface free energy and structure of the polymeric
textile products and other, often poorly defined, surface chemical and physical characteristics of the products influence
the interactions of these agents. The interactions of surface active agents, often derived from fats and oils, dissolved or
dispersed in liquids, with textile materials, including natural products such as cotton, wool and leather, as well as man-made
fibers, are considered in this symposium.
One of eight papers being published from the Symposium “Surface Active Agents in the Textile Industry,” presented at the AOCS
meeting in New Orleans, April 1970.
So. Utiliz. Res. Dev. Div., ARS, USDA. 相似文献