857 research outputs found

    Why Online Education Will Attain Full Scale

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    Online higher education has attained scale and is poised to take the next step in its growth. Although significant obstacles to a full scale adoption of online education remain, we will see full scale adoption of online higher education within the next five to ten years. Practically all higher education students will experience online education in some form during their collegiate career, and college students will be able to take an online or blended degree programs and certificates in almost any subject. Full scale online education will occur as the result of compounded growth, increased familiarity and acceptance, various models of scalability, and possible ‘wildcards’ which may accelerate growth. Online education will also attain full scale by becoming fully integrated into mainstream education. This transformation is necessary for online learning to reach its potential to improve the quality of education

    Milk Lactose Hydrolysis In A Batch Reactor: Optimisation Of Process Parameters, Kinetics Of Hydrolysis And Enzyme Inactivation

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    The present investigation describes the effects of the process quantities on enzymatic hydrolysis of milk lactose and enzyme stability. The lactose hydrolysis reactions were carried out in 250 mL of milk by using a commercial β-galactosidase produced from Kluyveromyces marxianus lactis. The residual lactose mass concentration (g L-1) and residual enzyme activity (%) against time were investigated vs. process variables such as temperature, impeller speed and enzyme concentration. Optimum conditions for hydrolysis were obtained as 37 °C, 300 rpm, 1 mL L-1 enzyme concentration and 30 min of processing time. The lactose hydrolysis process resulted in 84 % of hydrolysis degree and 52 % of residual enzyme activity at the optimum experimental conditions obtained. After evaluation of the data, it was found that the kinetics of hydrolysis and enzyme inactivation could be represented by a first order kinetic model and a single-step non-first-order enzyme inactivation kinetic model for all process conditions applied. Also, to illustrate the effect of process variables on hydrolysis and enzyme stability, some modelling studies were performed. The activation energy for hydrolysis reaction (EA) was calculated as 50.685 kJ mol-1

    Preparation of Ion Imprinted SPR Sensor for Real-Time Detection of Silver(I) Ion from Aqueous Solution

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    The aim of the submitted study is to develop molecular imprinting based surface plasmon resonance (SPR) sensor for real-time silver ion detection. For this purpose polymeric nanofilm layer on the gold SPR chip surface was prepared via UV polymerization of acrylic acid at 395 nm for 30 minutes. N-methacryloyl- L cysteine used as the functional monomer to recognize the silver(I) ions from the aqueous solutions and methylene bisacrylamide used as the crosslinker for obtaining structural rigidity of the formed cavities. Silver(I) solutions with different concentrations were applied to SPR system to investigate the efficiency of the imprinted SPR sensor in real time. For the control experiments, non-imprinted SPR sensor was also prepared as described above without addition of template “silver(I) ions”. Prepared SPR sensors were characterized with atomic force microscopy (AFM). In order to show the selectivity of the silver(I) imprinted SPR sensor, competitive adsorption of Cu(II), Pb(II), Ni(II) ions was investigated. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3489

    Noise Dressing of Financial Correlation Matrices

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    We show that results from the theory of random matrices are potentially of great interest to understand the statistical structure of the empirical correlation matrices appearing in the study of price fluctuations. The central result of the present study is the remarkable agreement between the theoretical prediction (based on the assumption that the correlation matrix is random) and empirical data concerning the density of eigenvalues associated to the time series of the different stocks of the S&P500 (or other major markets). In particular the present study raises serious doubts on the blind use of empirical correlation matrices for risk management.Comment: Latex (Revtex) 3 pp + 2 postscript figures (in-text

    Distribution of entanglement in light-harvesting complexes and their quantum efficiency

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    Recent evidence of electronic coherence during energy transfer in photosynthetic antenna complexes has reinvigorated the discussion of whether coherence and/or entanglement has any practical functionality for these molecular systems. Here we investigate quantitative relationships between the quantum yield of a light-harvesting complex and the distribution of entanglement among its components. Our study focusses on the entanglement yield or average entanglement surviving a time scale comparable to the average excitation trapping time. As a prototype system we consider the Fenna-Matthews-Olson (FMO) protein of green sulphur bacteria and show that there is an inverse relationship between the quantum efficiency and the average entanglement between distant donor sites. Our results suggest that longlasting electronic coherence among distant donors might help modulation of the lightharvesting function.Comment: Version accepted for publication in NJ

    A Random Matrix Model for Color Superconductivity at Zero Chemical Potential

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    We discuss random matrix models for the spontaneous breaking of both chiral and color symmetries at zero chemical potential and finite temperature. Exploring different Lorentz and gauge symmetric color structures of the random matrix interactions, we find that spontaneous chiral symmetry breaking is always thermodynamically preferred over diquark condensation. Stable diquark condensates appear only as SU(2) rotated chiral condensates, which do not represent an independent thermodynamic phase. Our analysis is based on general symmetry arguments and hence suggests that no stable and independent diquark phase can form in QCD with two flavors at zero quark chemical potential.Comment: 26 pages, 1 figure, uses ReVTeX and epsf.st

    Pseudo-unitary symmetry and the Gaussian pseudo-unitary ensemble of random matrices

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    Employing the currently discussed notion of pseudo-Hermiticity, we define a pseudo-unitary group. Further, we develop a random matrix theory which is invariant under such a group and call this ensemble of pseudo-Hermitian random matrices as the pseudo-unitary ensemble. We obtain exact results for the nearest-neighbour level spacing distribution for (2 X 2) PT-symmetric Hamiltonian matrices which has a novel form, s log (1/s) near zero spacing. This shows a level repulsion in marked distinction with an algebraic form in the Wigner surmise. We believe that this paves way for a description of varied phenomena in two-dimensional statistical mechanics, quantum chromodynamics, and so on.Comment: 9 pages, 2 figures, LaTeX, submitted to the Physical Review Letters on August 20, 200

    Factors Related to Accelerometer-determined Patterns of Physical Activity in Adults: The Houston TRAIN Study

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    Meeting U.S. Physical Activity (PA) Guidelines has health benefits. Yet, little is known about the factors related to changes in PA over time, particularly among minority populations. PURPOSE: To examine sociodemographic, PA preferences, and health factors related to accelerometer-derived patterns of 1-year PA change in the Houston Travel Related Activity in Neighborhoods (TRAIN) Study, a majority-minority cohort. METHODS: Participants wore an ActiGraph wGT3X-BT monitor and completed self-report surveys at baseline and follow-up. Valid wear time was defined as ≥ 4 days, ≥ 10 hrs/day. PA was stratified by meeting Guidelines using total MVPA, defined by Freedson. Four PA patterns were defined: (i) ‘maintain high’ activity above Guidelines, (ii) ‘increased’ to meet Guidelines, (iii) ‘decreased’ from meet to not meet Guidelines, and (iv) ‘maintained low’ activity. Multinomial logistic regression was used to examine associations between studied factors and each PA pattern, with the ‘maintain high’ group as referent. RESULTS: Complete data were available for 153 adults (19% maintained high activity, 8.5% increased, 13% decreased, 59.5% maintained low activity). Controlling for all variables, males (OR = 0.3, 95% CI = 0.1, 0.9) had lower odds of being in the ‘maintain low’ group. Blacks (vs. whites, OR = 18.8, 95% CI = 2.6, 275.0), those liking biking (vs. strongly liking, OR = 4.6, 95% CI = 1.3, 15.6), and older participants (vs. younger, on continuous scale, OR = 1.1, 95% CI = 1.0, 1.1) had higher odds of being in the ‘maintain low’ group. Factors directly associated with being in the ‘increased’ group were being black (vs. white, OR = 17.9, 95% CI = 1.3, 120.9), strong dislike for biking (vs. strongly liking OR = 25.2, 95% CI = 1.6, 401.3), and having more chronic diseases (vs. less, on continuous scale, 95% CI = 1.5, 11.7). Having low educational attainment (vs. high, OR = 0.04, 95% CI = 0.0, 0.9) was inversely associated with being in the ‘increased’ group. No studied factors were significantly associated with being in the ‘decreased’ group. CONCLUSION: PA patterns are dynamic and suggest that sociodemographic, PA preferences, and health factors relate to change patterns over time. Future studies should examine the role of these factors over longer follow-up periods, and consider these factors when designing interventions
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