The viscosity radius in dilute polymer solutions: Universal behaviour from DNA rheology and Brownian dynamics simulations

The swelling of the viscosity radius, $\alpha_\eta$, and the universal viscosity ratio, $U_{\eta R}$, have been determined experimentally for linear DNA molecules in dilute solutions with excess salt, and numerically by Brownian dynamics simulations, as a function of the solvent quality. In the latter instance, asymptotic parameter free predictions have been obtained by extrapolating simulation data for finite chains to the long chain limit. Experiments and simulations show a universal crossover for $\alpha_\eta$ and $U_{\eta R}$ from $\theta$ to good solvents in line with earlier observations on synthetic polymer-solvent systems. The significant difference between the swelling of the dynamic viscosity radius from the observed swelling of the static radius of gyration, is shown to arise from the presence of hydrodynamic interactions in the non-draining limit. Simulated values of $\alpha_\eta$ and $U_{\eta R}$ are in good agreement with experimental measurements in synthetic polymer solutions reported previously, and with the measurements in linear DNA solutions reported here.Comment: 19 pages, 14 figures, two column, Supporting Information added, to appear in Macromolecule

The role of dwelling type when estimating the effect of magnetic fields on childhood leukemia in the California Power Line Study (CAPS).

PurposeThe type of dwelling where a child lives is an important factor when considering residential exposure to environmental agents. In this paper, we explore its role when estimating the potential effects of magnetic fields (MF) on leukemia using data from the California Power Line Study (CAPS). In this context, dwelling type could be a risk factor, a proxy for other risk factors, a cause of MF exposure, a confounder, an effect-measure modifier, or some combination.MethodsWe obtained information on type of dwelling at birth on over 2,000 subjects. Using multivariable-adjusted logistic regression, we assessed whether dwelling type was a risk factor for childhood leukemia, which covariates and MF exposures were associated with dwelling type, and whether dwelling type was a potential confounder or an effect-measure modifier in the MF-leukemia relationship under the assumption of no-uncontrolled confounding.ResultsA majority of children lived in single-family homes or duplexes (70%). Dwelling type was associated with race/ethnicity and socioeconomic status but not with childhood leukemia risk, after other adjustments, and did not alter the MF-leukemia relationship upon adjustment as a potential confounder. Stratification revealed potential effect-measure modification by dwelling type on the multiplicative scale.ConclusionDwelling type does not appear to play a significant role in the MF-leukemia relationship in the CAPS dataset as a leukemia risk factor or confounder. Future research should explore the role of dwelling as an effect-measure modifier of the MF-leukemia association

AN EFFECTIVE REVERSIBLE DATA HIDING METHOD BASED ON PIXEL-VALUE-ORDERING

This paper presents a new effective reversible data hiding method based on pixel-value-ordering (iGePVO-K) which is improvement of a recent GePVO-K method that recently is considered as a PVO-used method having highest embedding capacity. In comparison with GePVO-K method, iGePVO-K has the following advantages. First, the embedding capacity of the new method is higher than that of GePVO-K method by using data embedding formulas reasonably and reducing the location map size. Second, for embedding data, in the new method, each pixel value is modified at most by one, while in GePVO-K method, each pixel value may be modified by two. In fact, in the GePVO-K method, the largest pixels are modified by two for embedding bits 1 and by one for bits 0. This is also true for the smallest pixels. Meanwhile, in the proposed method, the largest pixels are modified by one for embedding bits 1 and are unchanged if embedding bits 0. Therefore, the stego-image quality in proposed method is better than that in GePVO-K method. Theoretical analysis and experiment results show that the proposed method has higher embedding capacity and better stego image quality than GePVO-K method

Shear thinning in dilute and semidilute solutions of polystyrene and DNA

The viscosity of dilute and semidilute unentangled DNA solutions, in steady simple shear flow, has been measured across a range of temperatures and concentrations. For polystyrene solutions, measurements of viscosity have been carried out in the semidilute unentangled regime, while results of prior experimental measurements in the dilute regime have been used for the purpose of data analysis, and for comparison with the behaviour of DNA solutions. Interpretation of the shear rate dependence of viscosity in terms of suitably defined non-dimensional variables, is shown to lead to master plots, independent of temperature and concentration, in each of the two concentration regimes. In the case of semidilute unentangled solutions, defining the Weissenberg number in terms of a concentration dependent large scale relaxation time is found not to lead to data collapse across different concentrations. On the other hand, the use of an alternative relaxation time, with the concentration dependence of a single correlation blob, suggests the existence of universal shear thinning behaviour at large shear rates.Comment: 24 pages, 13 figures, supplementary material (see ancillary directory), to appear in Journal of Rheolog

Integration of SWAT and QUAL2K for water quality modeling in a data scarce basin of Cau River basin in Vietnam

© 2019 European Regional Centre for Ecohydrology of the Polish Academy of Sciences Water quality modeling in a river basin often faces the problem of having a large number of parameters yet limited available data. The important inputs to the water quality model are pollution concentrations and discharge from river tributaries, lateral inflows and related pollution load from different sources along the river. In general, such an extensive data set is rarely available, especially for data scarce basins. This makes water quality modeling more challenging. However, integration of models may be able to fill this data gap. Selection of models should be made based on the data that is available for the river basin. For the case of Cau River basin, the SWAT and QUAL2K models were selected. The outputs of SWAT model for lateral inflows and discharges of ungauged tributaries, and the observed pollutant concentrations data and estimated pollution loads of sub-watersheds were used as inputs to the water quality model QUAL2K. The resulting QUAL2K model was calibrated and validated using recent water quality data for two periods in 2014. Four model performance ratings PBIAS, NSE, RSR and R2 were used to evaluate the model results. PBIAS index was chosen for water quality model evaluation because it more adequately accounted for the large uncertainty inherent in water quality data. In term of PBIAS, the calibration and validation results for Cau River water quality model were in the “very good” performance range with ǀPBIASǀ < 15%. The obtained results could be used to support water quality management and control in the Cau River basin

Dividing Attention Between Tasks: Testing Whether Explicit Payoff Functions Elicit Optimal Dual-Task Performance

We test people's ability to optimize performance across two concurrent tasks. Participants performed a number entry task while controlling a randomly moving cursor with a joystick. Participants received explicit feedback on their performance on these tasks in the form of a single combined score. This payoff function was varied between conditions to change the value of one task relative to the other. We found that participants adapted their strategy for interleaving the two tasks, by varying how long they spent on one task before switching to the other, in order to achieve the near maximum payoff available in each condition. In a second experiment, we show that this behavior is learned quickly (within 2-3 min over several discrete trials) and remained stable for as long as the payoff function did not change. The results of this work show that people are adaptive and flexible in how they prioritize and allocate attention in a dual-task setting. However, it also demonstrates some of the limits regarding people's ability to optimize payoff functions

Can't go home

This thesis is a compilation of short stories around the theme of home. The characters struggle with how home shapes their values and desires. They seek to reconcile where they've come from with who they presently are and who they wish to become. Most of the characters are looking for a place to belong

Three essays on corporate debt mix, maturity structure, and inside debt compensation

In Chapter 1, we use a large sample of new debt to examine the determinants of corporate debt mix and to test the substitute/complement effects among debt sources. We find that both firm-level factors and macroeconomic variables are important determinants of debt mix. In addition, the set of determinants varies across time and economic conditions. In general, we find evidence for a substitution effect between public debt and private debt, both at rating downgrades and new issuance events. In Chapter 2, we examine the impacts of product market competition and corporate governance on debt maturity. We find that firms in less competitive industries use more short-term maturity than firms in more competitive industries, while firms with weak corporate governance use less short-term maturity. However, there is mixed evidence on the impact of the interaction between product market competition and corporate governance on maturity. In Chapter 3, we study the relations between inside debt compensation and corporate policies. We find a positive relationship between inside debt and leverage, indicating that CEOs with higher inside debt holdings tend to use higher leverage. We also find strong (weak) evidence on the negative relationship between inside debt and R&amp;D activities (capital expenditures). We provide the first evidence about the relationship between inside debt and debt maturity. In one direction, short-term maturity increases in inside debt. However, in other direction, inside debt decreases in short-term maturity. Additionally, we document new evidence about the determinants of inside debt

Effects of lower extremity posture on hip strength and their influence on lower extremity motion during a single leg squat

"This research investigated the effects of static lower extremity posture on hip strength, and then examined their collective influence on knee and hip joint kinematics during a single leg squat in males and females. Thirty one healthy males and 31 healthy females, predominantly college students, between the ages of 18 and 35 participated in a single data collection session during which six lower extremity posture characteristics were measured, followed by measurement of hip abduction and extension strength and concluded with neuromuscular and kinematic analysis of the hip and knee during a single leg squat. Hip torque was normalized to body mass and electromyographic data were normalized to maximum voluntary isometric contractions. Five single leg squats were performed on the dominant stance limb to a depth of 60° of knee flexion. Path analysis, implemented by structural equation modeling, was used to examine whether greater lower extremity posture characteristics predicted decreased hip torque and whether greater lower extremity posture characteristics and decreased hip torque collectively predicted greater dynamic valgus knee motion (increased hip adduction and internal rotation, and knee external rotation and valgus). Separate multivariate analyses of variance determined whether females and males differed on measures of lower extremity posture, hip strength, and total hip and knee motion during the single leg squat. The findings were that greater hip anteversion predicted decreased hip abduction torque, and greater tibiofemoral angle predicted decreased hip extension torques. Direct relationships were noted between greater hip anteversion and genu recurvatum with greater knee external rotation, and between greater navicular drop and hip anteversion with greater hip internal rotation during the single leg squat. Furthermore, decreased hip abduction torque predicted greater knee external rotation while decreased hip extension torque predicted greater knee valgus during a single leg squat. Hence, it was concluded that greater lower extremity posture characteristics predicted decreased posterio-lateral hip strength, and collectively, greater lower extremity posture characteristics and decrease posterio-lateral hip strength predicted greater functional valgus collapse during the single leg squat."--Abstract from author supplied metadata