Particle Characterization and Settling Velocities for a Water Supply Reservoir during a Turbidity Event

Characterization of the particle population for a location in a water supply reservoir, Kensico Reservoir, N.Y., is documented for a high turbidity event, from its onset, through alum treatment and its waning. Supporting in situ measurements included the beam attenuation coefficient at 670?nm (c670) and 660?nm (c660) [surrogates of turbidity (Tn)], particle concentrations (N) and size distributions (PSDs), and size class specific settling velocities (SVs). Laboratory measurements included chemical and morphometric analyses of individual particles, and routine measurements of Tn. The turbidity is shown to be primarily derived from clay minerals, mostly in the size range of 1.5–6?μm. An initial high c670 level (40?m?1;Tn ～ 100?NTU) decreased sevenfold in less than 1?week in response to alum treatment that largely eliminated the particle size classes responsible for the elevated turbidity. Successful SV experiments, made using a laser in situ scattering and transmissometry (LISST) instrument, for seven particle size classes in the range of 1.25–129?μm yielded SV values of 0.17–69.4?m?day?1. Size classes larger than ～ 5?μm settled much slower than Stokes law predictions, before alum treatment, indicating that these classes existed as porous flocs or aggregates. Decreases in SVs following treatment suggest changes in floc character consistent with increased porosity. In situ measurements of c670, N, PSDs, and SVs can contribute to the development and testing of a multiple particle size class model to simulate fate, transport, and impacts of suspended particles.     

Algorithms for discrete and continuous multicommodity flow network interdiction problems

We consider a network interdiction problem on a multicommodity flow network, in which an attacker disables a set of network arcs in order to minimize the maximum profit that can be obtained from shipping commodities across the network. The attacker is assumed to have some budget for destroying (or “interdicting”) arcs, and each arc is associated with a positive interdiction expense. In this paper, we examine problems in which interdiction must be discrete (i.e., each arc must either be left alone or completely destroyed), and in which interdiction can be continuous (the capacities of arcs may be partially reduced). For the discrete problem, we describe a linearized model for optimizing network interdiction that is similar to previous studies in the field, and compare it to a penalty model that does not require linearization constraints. For the continuous case, we prescribe an optimal partitioning algorithm along with a heuristic procedure for estimating the optimal objective function value. We demonstrate on a set of randomly generated test data that our penalty model for the discrete interdiction problem significantly reduces computational time when compared to that consumed by the linearization model.     

Categorization of novel animals by patients with Alzheimer's disease and corticobasal degeneration.

We taught a novel animal category by rule-based and similarity-based processes to participants with Alzheimer's disease (AD), corticobasal degeneration (CBD), and healthy age-matched participants. Healthy participants successfully categorized by either process. AD patients' rule-based categorization was impaired, while their similarity-based categorization resembled that of healthy participants. Correlations of AD patients' performance with measures of executive functioning suggested a deficit in the cognitive resources necessary for engaging rule-based categorization. The contribution of limited executive resources to categorization difficulty in AD was further demonstrated in a second experiment in which features determining category membership were of lower salience. CBD patients were relatively impaired at similarity-based processing, suggesting that qualitatively distinct categorization processes can be selectively compromised in patients with focal neurodegenerative diseases. Moreover, AD patients' impaired categorization correlated with performance on a measure of semantic memory, implicating this categorization deficit in AD patients' semantic memory difficulty. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Task control and cognitive abilities of self and spouse in collaboration in middle-aged and older couples": Erratum.

Reports an error in "Task control and cognitive abilities of self and spouse in collaboration in middle-aged and older couples" by Cynthia A. Berg, Timothy W. Smith, Kelly J. Ko, Nancy J. M. Henry, Paul Florsheim, Gale Pearce, Bert N. Uchino, Michelle A. Skinner, Ryan M. Beveridge, Nathan Story and Kelly Glazer (Psychology and Aging, 2007[Sep], Vol 22[3], 420-427). Due to an editing mistake, the order of authorship was incorrect. The correct order is as follows: Berg, Smith, Ko, Beveridge, Story, Henry, Florsheim, Pearce, Uchino, Skinner, & Glazer. (The following abstract of the original article appeared in record 2007-13103-002.) Collaborative problem solving may be used by older couples to optimize cognitive functioning, with some suggestion that older couples exhibit greater collaborative expertise. The study explored age differences in 2 aspects of collaborative expertise: spouses' knowledge of their own and their spouse's cognitive abilities and the ability to fit task control to these cognitive abilities. The participants were 300 middle-aged and older couples who completed a hypothetical errand task. The interactions were coded for control asserted by husbands and wives. Fluid intelligence was assessed, and spouses rated their own and their spouse's cognitive abilities. The results revealed no age differences in couple expertise, either in the ability to predict their own and their spouse's cognitive abilities or in the ability to fit task control to abilities. However, gender differences were found. Women fit task control to their own and their spouse's cognitive abilities; men only fit task control to their spouse's cognitive abilities. For women only, the fit between control and abilities was associated with better performance. The results indicate no age differences in couple expertise but point to gender as a factor in optimal collaboration. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Can emotions be truly group level? Evidence regarding four conceptual criteria.

Recent advances in understanding prejudice and intergroup behavior have made clear that emotions help explain people's reactions to social groups and their members. Intergroup emotions theory (D. M. Mackie, T. Devos, & E. R. Smith, 2000; E. R. Smith, 1993) holds that intergroup emotions are experienced by individuals when they identify with a social group, making the group part of the psychological self. What differentiates such group-level emotions from emotions that occur purely at the individual level? The authors argue that 4 key criteria define group-level emotions: Group emotions are distinct from the same person's individual-level emotions, depend on the person's degree of group identification, are socially shared within a group, and contribute to regulating intragroup and intergroup attitudes and behavior. Evidence from 2 studies supports all 4 of these predictions and thus points to the meaningfulness, coherence, and functionality of group-level emotions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Full Electromagnetic Analysis of Grooved-Dielectric Fresnel Zone Plate Antennas for Microwave and Millimeter-Wave Applications

Grooved-dielectric, phase-correcting, Fresnel zone plate antennas are analyzed using the body-of-revolution finite-difference time-domain (BOR-FDTD) method. Parametric studies of the focusing ability of these antennas are performed to examine the effects of the focal length, diameter, number of zones, and the thickness of the lens, as well as the number of phase corrections per zone. The results of these studies are presented as design graphs and are used to lend insight into the focusing mechanism of phase-correcting zone plates. The BOR-FDTD analysis is validated by comparison with previous measurements.     

Microwave focusing and beam collimation using negative index of refraction lenses

Negative index of refraction materials (NIMs) were first postulated by Veselago in 1968 and have recently been realised using structures formed with rings and wires deposited on printed circuit boards. The proof of the existence of negative index of refraction was established using a Snell's law experiment with a wedge. The predicted and measured refraction angles were found to be consistent for a negative index material and in excellent agreement with the theoretical expectations. For microwave lenses NIMs have the advantage of being lighter, having better focusing properties and potentially lower aberrations. Simulation and experimental results on NIM configurations including gradient index of refraction and spherical 3D lenses are presented. Both focusing and beam collimating applications will be considered. These results will be compared to normal positive index of refraction material lenses     

Performance analysis of multiple-input multipleoutput singular value decomposition transceivers during fading and other cell interference

A generalised method is derived to compute the error probabilities of singular value decomposition (SVD)-based receivers for a multiple-input multiple-output (MIMO) system with uncoded transmission. The method can be used for a wide class of flat fading environments, including independent and identically distributed (i.i.d.) and semi-correlated Rayleigh and i.i.d. Ricean channels. Although the method is applied to equal-power binary phase shift keying, it can easily be extended to higher-order M-ary phase shift keying (M-PSK) and M-ary quadrature amplitude modulation (M-QAM) signal constellations and adaptive 'water-filling' schemes. The error probability curves derived from closed-form formulas and simulations demonstrate very close agreement. The error performances of channel inversion, minimum mean square error and zero forcing receivers are compared with the SVD receiver for a single-user system. The impact of multiple users is considered by studying the performance of an adaptive MIMO SVD transmission scheme operating in a cellular environment. In particular, the effect of inter-cell interference on the performance of the scheme is quantified, modelling the interference as increased Gaussian noise. A number of cellular layouts are examined and the impact of the resulting singal-to-interference and noise ratio on the constellation sizes that can be supported, the BER and so on is considered. The primary metric used for our performance analysis is the error-free transmission rate, which is derived for our adaptive system. For the cellular scenarios considered, it can be found that the effect of interference is considerable and the performance of the adaptive MIMO SVD scheme is only marginally better than that provided by conventional diversity methods.     

Optical Frequency Metrology of an Iodine-Stabilized He-Ne Laser Using the Frequency Comb of a Quantum-Interference-Stabilized Mode-Locked Laser

We perform optical frequency metrology of an iodine-stabilized He-Ne laser using a mode-locked Ti:sapphire laser frequency comb that is stabilized using quantum interference of photocurrents in a semiconductor. Using this technique, we demonstrate carrier-envelope offset frequency fluctuations of less than 5 mHz using a 1 s gate time. With the resulting stable frequency comb, we measure the optical frequency of the iodine transition [¹²⁷I₂ R(127) 11-5 i component] to be 473 612 214 712.96 ± 0.66 kHz, well within the uncertainty of the CIPM recommended value. The stability of the quantum interference technique is high enough such that it does not limit the measurements.     

Performing detailed power system studies for designing and analyzing electrical distribution systems - Power system studies for cement plants

The power system studies for designing and analyzing the electrical distribution system for cement plants is detailed. The analysis consists of a short circuit, load flow, motor starting over-current coordination, and arc flash hazard study. There are several load flow solution algorithms used in industry such as Gauss-Seidel, Newton-Raphson, and current injection. It is good engineering practice to have an up-to-date load flow study for every installation.