Non-uniform Rate Research Articles

40Ar/39Ar ages of muscovites from modern Himalayan rivers: Himalayan evolution and the relative contribution of tectonics and climate

40Ar/39Ar ages from detrital muscovites have been analyzed from six modern rivers in central and western Nepal; the size of the drainage basins associated with these samples ranges from a few square kilometers to >40,000 km2. These data, when combined with previously published ages of detrital muscovites from other modern rivers in the region, suggest that a good correspondence between normalized age and normalized topography (the comparison of t * and z *) is rare, due to either nonuniform rates of passage through the ∼400 °C isotherm or subsequent faulting in the drainage area. The closure temperature of Ar in muscovite is perhaps too high to make meaningful comparisons to modern topography in tectonic analysis of active orogens. The distribution of 40Ar/39Ar ages from detrital muscovites from the Karnali basin in western Nepal is much older than that for the Narayani basin in central Nepal. The Karnali muscovites, when combined with previously published muscovites from the Siwalik Group in western Nepal and zircon fission track ages from modern and ancient samples from the region, suggest a thermal history for western Nepal consistent with vigorous tectonics (and attendant erosion) before the middle Miocene but a significant diminution in the rate of erosion since ca. 10 Ma. 40Ar/39Ar ages of detrital muscovites from the Narayani basin in central Nepal suggest a markedly different history with an acceleration of the rate of erosion since ca. 10 Ma and reactivation of major faults; this is consistent with the abundant bedrock data from the Narayani basin. The strong difference in the erosional history of the adjacent Karnali and Narayani basins, as evidenced by the 40Ar/39Ar ages from detrital muscovites, is not likely to have been due to variations in climate, but rather due to strain partitioning within the Himalaya during and after the Miocene.

Chromosomal Rearrangements as Barriers to Genetic Homogenization between Archaic and Modern Humans.

Chromosomal rearrangements, which shuffle DNA throughout the genome, are an important source of divergence across taxa. Using a paired-end read approach with Illumina sequence data for archaic humans, I identify changes in genome structure that occurred recently in human evolution. Hundreds of rearrangements indicate genomic trafficking between the sex chromosomes and autosomes, raising the possibility of sex-specific changes. Additionally, genes adjacent to genome structure changes in Neanderthals are associated with testis-specific expression, consistent with evolutionary theory that new genes commonly form with expression in the testes. I identify one case of new-gene creation through transposition from the Y chromosome to chromosome 10 that combines the 5'-end of the testis-specific gene Fank1 with previously untranscribed sequence. This new transcript experienced copy number expansion in archaic genomes, indicating rapid genomic change. Among rearrangements identified in Neanderthals, 13% are transposition of selfish genetic elements, whereas 32% appear to be ectopic exchange between repeats. In Denisovan, the pattern is similar but numbers are significantly higher with 18% of rearrangements reflecting transposition and 40% ectopic exchange between distantly related repeats. There is an excess of divergent rearrangements relative to polymorphism in Denisovan, which might result from nonuniform rates of mutation, possibly reflecting a burst of transposable element activity in the lineage that led to Denisovan. Finally, loci containing genome structure changes show diminished rates of introgression from Neanderthals into modern humans, consistent with the hypothesis that rearrangements serve as barriers to gene flow during hybridization. Together, these results suggest that this previously unidentified source of genomic variation has important biological consequences in human evolution.

Numerical optimization of catalyst configurations in a solar parabolic trough receiver–reactor with non-uniform heat flux

A three-dimensional numerical model of a solar parabolic trough receiver–reactor (SPTRR) with methanol steam reforming reaction was developed. Based on this model, the characteristics of hydrodynamics, heat transfer and chemical reaction of SPTRR were studied. Also, the effects of non-uniform heat flux boundary condition, catalyst layout and mass flow rate on the performances of SPTRR were analyzed. The results showed that SPTRRs partially filled with catalyst have better comprehensive performance than those fully filled with catalyst, and the SPTRR with horizontal cylindrical segment shaped catalyst in the lower part of receiver tube is recommended to substitute the fully catalyst-filled SPTRR. The chemical energy conversion per unit pump power of the proposed partially catalyst-filled SPTRR is one order of magnitude larger than that of the fully catalyst-filled SPTRR, and the mean outer surface temperature and maximum outer surface temperature difference of the proposed partially catalyst-filled SPTRR can be as low as that of the fully catalyst-filled SPTRR, when the mass of the catalyst in the partially catalyst-filled SPTRR is 0.4 times as much as that in the fully catalyst-filled SPTRR.

On contact-line dynamics with mass transfer

We investigate the effect of mass transfer on the evolution of a thin, two-dimensional, partially wetting drop. While the effects of viscous dissipation, capillarity, slip and uniform mass transfer are taken into account, other effects, such as gravity, surface tension gradients, vapour transport and heat transport, are neglected in favour of mathematical tractability. Our focus is on a matched-asymptotic analysis in the small-slip limit, which reveals that the leading-order outer formulation and contact-line law depend delicately on both the sign and the size of the mass transfer flux. This leads, in particular, to novel generalisations of Tanner's law. We analyse the resulting evolution of the drop on the timescale of mass transfer and validate the leading-order predictions by comparison with preliminary numerical simulations. Finally, we outline the generalisation of the leading-order formulations to prescribed non-uniform rates of mass transfer and to three dimensions.

Integrated design and performance analysis of the KO HCCR TBM for ITER

To develop tritium breeding technology for a Fusion Reactor, Korea has participated in the Test Blanket Module (TBM) program in ITER. The He Cooled Ceramic Reflector (HCCR) TBM consists of functional components such as First Wall (FW), Breeding Zone (BZ), Side Wall (SW), and Back Manifold (BM) and it was designed based on the separate analyses for each component in 2012. Based on the each component analysis model, the integrated model is prepared and thermal-hydraulic analysis for the HCCR TBM is performed in the present study. The coolant flow distribution from BM and SW to FW and BZ, and resulted structure temperatures are obtained with the integrated model. It is found that the non-uniform flow rate occurs at FW and BZ and it causes excess of the design limit (550°C) at some region. Based on this integrated model, we will perform the design optimization for obtaining uniform flow distribution for satisfying the design requirements.

The missing nano-architecture found in the barrier layer of porous anodic alumina

Abstract Hexagrams were revealed on the barrier layer of porous anodic alumina during chemical etching and ion milling, indicating non-uniform etching. Six-membered ring structure holes appear firstly around the center of each cell and subsequently merge into a primary circular opening. A new pore-opening mechanism is proposed, and the possible origin of the non-uniform etching rate is also discussed.

On an LMI approach to optimal sampled-data state feedback control design

The literature presents a large number of interesting and useful results on sampled-data systems. In this paper, we deal with control design problems for this class of systems following a different route. The novelty is that the optimal and state feedback control design problems for sampled-data linear systems are solved in a unified and direct manner through linear matrix inequalities. To this purpose, the solution to a special two-point boundary value problem is used to verify the stability and to evaluate the performance of the closed-loop system. These results are then generalised to cope with non-uniform data rates. The theory is illustrated by means of simple examples borrowed from the literature.

Solving Rule-Consequentialism's Acceptance Rate Problem

Recent formulations of rule-consequentialism (RC) have attempted to select the ideal moral code based on realistic assumptions of imperfect acceptance. But this introduces further problems. What assumptions about acceptance would be realistic? And what criterion should we use to identify the ideal code? The solutions suggested in the recent literature – Fixed Rate RC, Variable Rate RC, Optimum Rate RC and Maximizing Expectation Rate RC – all calculate a code's value using formulas that stipulate some uniform rate(s) of acceptance. After pointing out a number of difficulties with these approaches, I introduce a formulation of RC on which non-uniform acceptance rates are calculated rather than stipulated. In addition to making more realistic assumptions about acceptance rates, Calculated Rates RC has several other advantages: it gives equal consideration to both acceptance and compliance rates and it brings RC more in line with our intuitive ways of thinking about rules and their consequences.

Suppression of Defective Data Artifacts for Deblurring Images Corrupted by Random Valued Noise

For deblurring images corrupted by random valued noise, two-phase methods first select likely-to-be reliables (data that are not corrupted by random valued noise) and then deblur images only with selected data. Two-phase methods, however, often cause defective data artifacts, which are mixed results of missing data artifacts caused by the lack of data and noisy data artifacts caused mainly by falsely selected outliers (data that are corrupted by random valued noise). In this paper, to suppress these defective data artifacts, we propose a blurring model based reliable-selection technique to select reliables as many as possible to make all of to-be-recovered pixel values to contribute to selected data, while excluding outliers as accurately as possible. We also propose a normalization technique to compensate for non-uniform rates in recovering pixel values. We conducted simulation studies on Gaussian and diagonal deblurring to evaluate the performance of proposed techniques. Simulation results showed that proposed techniques improved the performance of two-phase methods, by suppressing defective data artifacts effectively.

Four genes predict high risk of progression from smoldering to symptomatic multiple myeloma (SWOG S0120)

Multiple myeloma is preceded by an asymptomatic phase, comprising monoclonal gammopathy of uncertain significance and smoldering myeloma. Compared to the former, smoldering myeloma has a higher and non-uniform rate of progression to clinical myeloma, reflecting a subset of patients with higher risk. We evaluated the gene expression profile of smoldering myeloma plasma cells among 105 patients enrolled in a prospective observational trial at our institution, with a view to identifying a high-risk signature. Baseline clinical, bone marrow, cytogenetic and radiologic data were evaluated for their potential to predict time to therapy for symptomatic myeloma. A gene signature derived from four genes, at an optimal binary cut-point of 9.28, identified 14 patients (13%) with a 2-year therapy risk of 85.7%. Conversely, a low four-gene score (< 9.28) combined with baseline monoclonal protein < 3 g/dL and albumin ≥ 3.5 g/dL identified 61 patients with low-risk smoldering myeloma with a 5.0% chance of progression at 2 years. The top 40 probe sets showed concordance with indices of chromosome instability. These data demonstrate high discriminatory power of a gene-based assay and suggest a role for dysregulation of mitotic checkpoints in the context of genomic instability as a hallmark of high-risk smoldering myeloma.

Prediction of Channel Diameter to Reduce Flow Mal Distribution in Radiators using ANN

Background/Objectives: The non-uniform flow of fluid over parallel channels having a common inlet and outlet is called flowmaldistribution.Theproblemofflowmaldistributionispredominantinheatexchangersandaffects theirperformances by increasing the pressure drop over the channels and has non-uniform mass flow rate. Methods/Statistical Analysis:In the present study a numerical model using commercial code ANSYS FLUENT © of a cross flow heat exchanger is presented and validated with experimental results. The main objective of the study is to optimize the heat exchanger to reduce the mal-distribution of the fluid. A Soft computing technique, Artificial Neural Network (ANN) is used to predict and optimize the size of the heat exchanger. The neural network is trained by results obtained from the numerical simulations for differentRceosnudlittsi:oIntsh. as been found that the flow mal distribution is minimum when the individual channel diameter is minimum. Increasing the channel diameter increases the non-uniformity in the mass flow rate. It has been ascertained from the mean standard deviation based on Neural network prediction that reducing the diameter of the channels 11 and 12 plays a major role in reducing the flow mal distribution inside the heat exchanger. Conclusion/Application: The trained neural network predicts the mass flow rate. Based on these results the heat exchanger is optimized to minimize the flow mal distribution. This Neural network can further be implemented for any design.Keywords: Artificial Neural Network, Flow Mal-distribution, Heat Exchanger, Mass Flow Rate, Numerical Simulations

WEST NILE VIRUS ANTIBODY DECAY RATE IN FREE-RANGING BIRDS.

Antibody duration, following a humoral immune response to West Nile virus (WNV) infection, is poorly understood in free-ranging avian hosts. Quantifying antibody decay rate is important for interpreting serologic results and for understanding the potential for birds to serorevert and become susceptible again. We sampled free-ranging birds in Chicago, Illinois, US, from 2005 to 2011 and Atlanta, Georgia, US, from 2010 to 2012 to examine the dynamics of antibody decay following natural WNV infection. Using serial dilutions in a blocking enzyme-linked immunosorbent assay, we quantified WNV antibody titer in repeated blood samples from individual birds over time. We quantified a rate of antibody decay for 23 Northern Cardinals (Cardinalis cardinalis) of 0.198 natural log units per month and 24 individuals of other bird species of 0.178 natural log units per month. Our results suggest that juveniles had a higher rate of antibody decay than adults, which is consistent with nonlinear antibody decay at different times postexposure. Overall, most birds had undetectable titers 2 yr postexposure. Nonuniform WNV antibody decay rates in free-ranging birds underscore the need for cautious interpretation of avian serology results in the context of arbovirus surveillance and epidemiology.

Noise-Tolerant Explicit Stencil Computations for Nonuniform Process Execution Rates

Next-generation HPC computing platforms are likely to be characterized by significant, unpredictable nonuniformities in execution time among compute nodes and cores. The resulting load imbalances from this nonuniformity are expected to arise from a variety of sources—manufacturing discrepancies, dynamic power management, runtime component failure, OS jitter, software-mediated resiliency, and TLB/- cache performance variations, for example. It is well understood that existing algorithms with frequent points of bulk synchronization will perform relatively poorly in the presence of these sources of process nonuniformity. Thus, recasting classic bulk synchronous algorithms into more asynchronous, coarse-grained parallelism is a critical area of research for next-generation computing. We propose a class of parallel algorithms for explicit stencil computations that can tolerate these nonuniformities by decoupling per process communication and computation in order for each process to progress asynchronously while maintaining solution correctness. These algorithms are benchmarked with a 1D domain decomposed (“slabbed”) implementation of the 2D heat equation as a model problem, and are tested in the presence of simulated nonuniform process execution rates. The resulting performance is compared to a classic bulk synchronous implementation of the model problem. Results show that the runtime of this article’s algorithm on a machine with simulated process nonuniformities is 5--99% slower than the runtime of its classic counterpart on a machine free of nonuniformities. However, when both algorithms are run on a machine with comparable synthetic process nonuniformities, this article’s algorithm is 1--37 times faster than its classic counterpart.

Thermal structure, rock exhumation, and glacial erosion of the Namche Barwa Peak, constraints from thermochronological data

In this paper, we report thermochronological data from the southwest slope of Namche Barwa Peak, the core region of the eastern Himalayan syntaxis. The data include apatite fission track (AFT) ages of ten bedrock samples ranging from 0.5±0.1 to 3.5±0.5 Myr and biotite 40Ar/39Ar ages from 2.53±0.14 to 5.57±0.19 Myr, corresponding to elevations from 5370 to 3060m. These ages are characterized by inverted age-elevation relationships (AERs), and the AERs of the AFT ages and the biotite 40Ar/39Ar ages are approximately parallel. Numerical modeling suggests that a possible change in the surface topography or faulting in this region could not have led to the observed inverted AERs. These observed ages demonstrate that a field of nonuniform exhumation rates existed in the relatively shallow crust (above the 110°C isotherm) of the Namche Barwa Peak region. The exhumation rates increase significantly from 0.3km/Myr to 5km/Myr with increasing proximity to the peak. However, the exhumation rates in the relatively deep crust (below the 110°C isotherm) of the same area are uniform at approximately 1.7km/Myr. This distinctive exhumation field and the strong spatial correlation between the intense glacial erosion and high rock exhumation rate of Namche Barwa Peak suggest that glacial erosion most likely drives the rapid exhumation of Namche Barwa Peak.

Evaluation of microchannel condenser characteristics by numerical simulation

This paper presents the development of a finite-volume-based numerical condenser model that considers important factors such as non-uniform air temperature and velocity at the front, fin conduction, refrigerant-side maldistribution caused by pressure balance between tubes, and air-side distribution for multislabs. Air-side and refrigerant-side microscale heat transfer and pressure drop correlations are carefully compared. The model results match well with lab test results for one-slab and two-slab microchannel heat exchangers on heat transfer and pressure drop. Several simulations are conducted to determine the impact of return air temperature, tube wall temperature, and non-uniform refrigerant flow rate. In addition, optimization results are analyzed by changing the number of flat tubes in each pass for both types of heat exchangers.

Trade-offs between tRNA abundance and mRNA secondary structure support smoothing of translation elongation rate.

Translation of protein from mRNA is a complex multi-step process that occurs at a non-uniform rate. Variability in ribosome speed along an mRNA enables refinement of the proteome and plays a critical role in protein biogenesis. Detailed single protein studies have found both tRNA abundance and mRNA secondary structure as key modulators of translation elongation rate, but recent genome-wide ribosome profiling experiments have not observed significant influence of either on translation efficiency. Here we provide evidence that this results from an inherent trade-off between these factors. We find codons pairing to high-abundance tRNAs are preferentially used in regions of high secondary structure content, while codons read by significantly less abundant tRNAs are located in lowly structured regions. By considering long stretches of high and low mRNA secondary structure in Saccharomyces cerevisiae and Escherichia coli and comparing them to randomized-gene models and experimental expression data, we were able to distinguish clear selective pressures and increased protein expression for specific codon choices. The trade-off between secondary structure and tRNA-concentration based codon choice allows for compensation of their independent effects on translation, helping to smooth overall translational speed and reducing the chance of potentially detrimental points of excessively slow or fast ribosome movement.

Multiscale modeling and operation of PECVD of thin film solar cells

This work proposes a multiscale modeling and operation framework for plasma-enhanced chemical vapor deposition (PECVD) of thin film silicon solar cells with uniform thickness and film surface microstructure that optimizes light trapping. Specifically, we focus on a single-wafer parallel-electrode PECVD process with showerhead arrangement and develop a multiscale model capturing both the gas-phase reaction and transport phenomena that lead to the deposition of the thin film across the wafer as well as multiple microscopic models that describe the evolution of the thin film surface microstructure at equispaced, discrete spatial locations across the wafer. While the modeling of chemical reactions and transport-phenomena (both diffusion and convection) in the gas-phase adopts the continuum hypothesis and is based on two-dimensional in space partial differential equations, a novel microscopic model is developed for the a-Si:H thin film surface evolution, which accounts for four microscopic processes: physisorption, surface migration, hydrogen abstraction and chemisorption. A hybrid kinetic Monte Carlo (kMC) algorithm is utilized to reduce computational requirements without compromising the accuracy of established chemical models that account for interactions amongst physisorbed radicals, and the microscopic model fidelity is established though calibration with experimentally obtained growth rates and surface morphology data. The results of the multiscale process model indicate that in order to produce a thin film with a diameter of 20cm and a uniform thickness with surface microstructure that optimizes light trapping: (a) a sinusoidally grated wafer surface should be used in which the grating period and depth should correspond to values that lead to film surface roughness and height–height correlation length that are on the order of visible light wavelength range, and (b) the substrate temperature should be adjusted, along several concentric zones across the substrate, to compensate for a radially non-uniform deposition rate of the film on the wafer owing to gas-phase transport phenomena. Due to the dependence of film growth rate on substrate temperature, the wafer surface is separated into four concentric zones, each with an independent heating element. Extensive simulations demonstrate that the use of appropriate sinusoidal wafer grating and the regulation of substrate temperature provide a viable and effective way for the PECVD of thin film silicon solar cells with uniform thickness and film surface microstructure that optimizes light trapping.

Sampled-Data Piecewise Affine Differential Inclusions

This paper addresses exponential stability and stabilization of sampled-data piecewise affine differential inclusions (PWADI) with an unknown nonuniform sampling rate. The contributions of this paper are threefold. First, given a controller, sufficient conditions for exponential stability of closed-loop sampled-data PWADI are presented using a piecewise smooth Krasovskii functional. Second, assuming the controller is piecewise linear and the Krasovskii functional is piecewise quadratic, the stability conditions are cast as linear matrix inequalities (LMIs). Third, sufficient conditions for sampled-data controller synthesis for PWADI are formulated in terms of LMIs, with the maximum allowable sampling period as a parameter. The effectiveness of the approach is shown via a PWADI example that is motivated by a nonlinear system.

On Operation of PECVD of Thin Film Solar Cells

This work proposes a multiscale model-based operation framework for large-area plasma-enhanced chemical vapor deposition (PECVD) of thin film silicon solar cells with uniform thickness and film surface microstructure that optimizes light trapping. The results of a multiscale process model indicate that in order to manufacture a thin film with a diameter of 20 cm and a uniform thickness with surface microstructure that optimizes light trapping: a) a sinusoidally-grated wafer surface should be used in which the grating period and depth should correspond to values that lead to film surface roughness on the order of visible light wavelength range, and b) the substrate temperature should be regulated, along several concentric zones across the substrate, to compensate for a radially non-uniform deposition rate of the film on the wafer owing to gas-phase transport phenomena. Due to the dependence of film growth rate on substrate temperature, the wafer surface is separated into four concentric zones, each with an independent heating element. Simulations demonstrate that the use of appropriate sinusoidal wafer grating and the regulation of substrate temperature provide a viable and effective way for the large-area PECVD of thin film silicon solar cells with uniform thickness and film surface microstructure that optimizes light trapping.

Modeling Pedestrian Level of Service at Signalized Intersection Crosswalks under Mixed Traffic Conditions

The objectives of this study were to identify the factors affecting the pedestrian level of service (LOS) at signalized intersection crosswalks under mixed traffic conditions and to develop a suitable method for estimating pedestrian LOS. The important factors influencing pedestrian LOS at crosswalks were summarized: turning traffic, through traffic, number of pedestrians, and pedestrian delay. In the Highway Capacity Manual method, pedestrian delay can be calculated by Webster's delay model, which assumes that pedestrians arrive at a uniform rate and comply with the signal at an intersection. However, that assumption is not suitable for the Chinese scenario. A pedestrian delay model was developed by considering nonuniform arrival rates and noncompliant behavior under mixed traffic conditions. The data collected by video and a questionnaire survey include information on 1,257 participants' real-time sense of comfort and safety when crossing five selected intersections and on the operational characteristics of the intersections. With perceived LOS as a dependent variable, Pearson correlation analysis and linear regression techniques were explored to determine the significant factors affecting LOS. To overcome the limitations of linear regression techniques, cumulative logistic regression was done to develop a model that fits mixed traffic conditions in China—a model that can predict the probability of responses within each LOS on the basis of a combination of explanatory variables. The results showed that the cumulative logistic model fit the survey data better than the linear regression model and produces LOS A for the crosswalks.