2,630 research outputs found
Seed Yield Prediction Models of Four Common Moist-Soil Plant Species in Texas
Seed production by moist-soil plant species often varies within and among managed wetlands and on larger landscapes. Quantifying seed production of moist-soil plants can be used to evaluate wetland management strategies and estimate wetland energetic carrying capacity, specifically for waterfowl. In the past, direct estimation techniques were used, but due to excessive personnel and time costs, other indirect methods have been developed. Because indirect seed yield models do not exist for moist-soil plant species in east-central or coastal Texas, we developed direct and indirect methods to model seed production on regional managed wetlands. In September 2004 and 2005, we collected Echinochloa crusgalli (barnyard grass), E. walterii (wild millet), E. colona (jungle rice), and Oryza sativa (cultivated rice) for phytomorphological measurements and seed yield modeling. Initial simple linear and point of origin regression analyses demonstrate strong relationships (P \u3c 0.001) among phytomorphological and dot grid methods in predicting seed production for all four species. These models should help regional wetland managers evaluate moist-soil management success and create models for seed production for other moist-soil plants in this region
Decomposition of Three Common Moist-Soil Managed Wetland Plant Species
Moist-soil wetland management is used to precisely control delivery, duration, and timing of water addition to, and removal from, managed wetlands with targeted responses including germination and growth of desirable moist-soil plant species. Similarly, water delivery and removal drives decomposition of moist-soil plants as well as nutrient cycling within these systems, which is a key driver of productivity in such managed wetlands. Through deployment of litter bags, we examined rate of mass loss and decay coefficients of three locally abundant moist-soil annual species that are potentially valuable wintering-waterfowl food sources (nodding smartweed Persicaria lapathifolia, red-rooted flatnut sedge Cyperus erythrorhizos, and toothcup Ammannia coccinea) within man-made moist-soil managed wetlands on the Richland Creek Wildlife Management Area in East-central Texas. All three species lost nearly 100% of their mass during an 11-mo deployment period, where rate of mass lost and decay coefficient rates were driven by time, because all moist-soil managed wetlands used were inundated for the duration of this study. Plant materials exposed to persistent inundation in shallow wetlands exhibited rates of mass loss typical of the first two stages of decomposition, during which a majority of plant material mass was lost. However, during this study, typical inundation and drawdown regimes were not implemented, which may have delayed or prolonged decomposition processes, because litter bags of focal species were inundated for the duration of this study. Both locally and regionally specific moist-soil management hydroperiod manipulation should include both drawdown and inundation, to incorporate temporal transitions between these conditions. Such practices will allow wetland managers to more expeditiously meet plant management and waterfowl food production goals within moist-soil managed wetlands
Finding shuffle words that represent optimal scheduling of shared memory access
This is an Author's Accepted Manuscript of an article published in International Journal of Computer Mathematics [© Taylor & Francis], available online at: http://www.tandfonline.com/doi/abs/10.1080/00207160.2012.698007In the present paper, we introduce and study the problem of computing, for any given nite
set of words, a shu e word with a minimum so-called scope coincidence degree. The scope
coincidence degree is the maximum number of di erent symbols that parenthesise any position
in the shu e word. This problem is motivated by an application of a new automaton model
and can be regarded as the problem of scheduling shared memory accesses of some parallel
processes in a way that minimises the number of memory cells required. We investigate the
complexity of this problem and show that it can be solved in polynomial time
Letters to Andrew Inglis Clark, Tasmania from Walter Gill, Melbourne dated October 7 1883
Espouses his reverence and affection for Clark, a true friend. The illness that debilitated me in Sydney I am slowly shaking off. Witton is enjoying his new found freedom and has made many friends. We both went to hear Conway lecture on Emerson, and were disappointed with his delivery but were impressed with the man. Talks about his work and a new project which will take up much time. Complains about his brother not providing assistance to the family coffers.
C4/C14
Enhanced Gauge Groups in N=4 Topological Amplitudes and Lorentzian Borcherds Algebras
We continue our study of algebraic properties of N=4 topological amplitudes
in heterotic string theory compactified on T^2, initiated in arXiv:1102.1821.
In this work we evaluate a particular one-loop amplitude for any enhanced gauge
group h \subset e_8 + e_8, i.e. for arbitrary choice of Wilson line moduli. We
show that a certain analytic part of the result has an infinite product
representation, where the product is taken over the positive roots of a
Lorentzian Kac-Moody algebra g^{++}. The latter is obtained through double
extension of the complement g= (e_8 + e_8)/h. The infinite product is
automorphic with respect to a finite index subgroup of the full T-duality group
SO(2,18;Z) and, through the philosophy of Borcherds-Gritsenko-Nikulin, this
defines the denominator formula of a generalized Kac-Moody algebra G(g^{++}),
which is an 'automorphic correction' of g^{++}. We explicitly give the root
multiplicities of G(g^{++}) for a number of examples.Comment: 33 pages, 3 figure
The development and validation of the Virtual Tissue Matrix, a software application that facilitates the review of tissue microarrays on line
BACKGROUND: The Tissue Microarray (TMA) facilitates high-throughput analysis of hundreds of tissue specimens simultaneously. However, bottlenecks in the storage and manipulation of the data generated from TMA reviews have become apparent. A number of software applications have been developed to assist in image and data management; however no solution currently facilitates the easy online review, scoring and subsequent storage of images and data associated with TMA experimentation. RESULTS: This paper describes the design, development and validation of the Virtual Tissue Matrix (VTM). Through an intuitive HTML driven user interface, the VTM provides digital/virtual slide based images of each TMA core and a means to record observations on each TMA spot. Data generated from a TMA review is stored in an associated relational database, which facilitates the use of flexible scoring forms. The system allows multiple users to record their interpretation of each TMA spot for any parameters assessed. Images generated for the VTM were captured using a standard background lighting intensity and corrective algorithms were applied to each image to eliminate any background lighting hue inconsistencies or vignetting. Validation of the VTM involved examination of inter-and intra-observer variability between microscope and digital TMA reviews. Six bladder TMAs were immunohistochemically stained for E-Cadherin, β-Catenin and PhosphoMet and were assessed by two reviewers for the amount of core and tumour present, the amount and intensity of membrane, cytoplasmic and nuclear staining. CONCLUSION: Results show that digital VTM images are representative of the original tissue viewed with a microscope. There were equivalent levels of inter-and intra-observer agreement for five out of the eight parameters assessed. Results also suggest that digital reviews may correct potential problems experienced when reviewing TMAs using a microscope, for example, removal of background lighting variance and tint, and potential disorientation of the reviewer, which may have resulted in the discrepancies evident in the remaining three parameters
Continuum Halos in Nearby Galaxies -- an EVLA Survey (CHANG-ES) -- II: First Results on NGC 4631
We present the first results from the CHANG-ES survey, a new survey of 35
edge-on galaxies to search for both in-disk as well as extra-planar radio
continuum emission. The motivation and science case for the survey are
presented in a companion paper (Paper I). In this paper (Paper II), we outline
the observations and data reduction steps required for wide-band calibration
and mapping of EVLA data, including polarization, based on C-array test
observations of NGC 4631.
With modest on-source observing times (30 minutes at 1.5 GHz and 75 minutes
at 6 GHz for the test data) we have achieved best rms noise levels of 22 and
3.5 Jy beam at 1.5 GHz and 6 GHz, respectively. New disk-halo
features have been detected, among them two at 1.5 GHz that appear as loops in
projection. We present the first 1.5 GHz spectral index map of NGC 4631 to be
formed from a single wide-band observation in a single array configuration.
This map represents tangent slopes to the intensities within the band centered
at 1.5 GHz, rather than fits across widely separated frequencies as has been
done in the past and is also the highest spatial resolution spectral index map
yet presented for this galaxy. The average spectral index in the disk is
indicating that the emission is
largely non-thermal, but a small global thermal contribution is sufficient to
explain a positive curvature term in the spectral index over the band. Two
specific star forming regions have spectral indices that are consistent with
thermal emission. Polarization results (uncorrected for internal Faraday
rotation) are consistent with previous observations and also reveal some new
features. On broad scales, we find strong support for the notion that magnetic
fields constrain the X-ray emitting hot gas.Comment: Accepted to the Astronomical Journal, Version 2 changes: Added
acknowledgement to NRA
GPGPU computation and visualization of three-dimensional cellular automata
This paper presents a general-purpose simulation approach integrating a set of technological developments and algorithmic methods in cellular automata (CA) domain. The approach provides a general-purpose computing on graphics processor units (GPGPU) implementation for computing and multiple rendering of any direct-neighbor three-dimensional (3D) CA. The major contributions of this paper are: the CA processing and the visualization of large 3D matrices computed in real time; the proposal of an original method to encode and transmit large CA functions to the graphics processor units in real time; and clarification of the notion of top-down and bottom-up approaches to CA that non-CA experts often confuse. Additionally a practical technique to simplify the finding of CA functions is implemented using a 3D symmetric configuration on an interactive user interface with simultaneous inside and surface visualizations. The interactive user interface allows for testing the system with different project ideas and serves as a test bed for performance evaluation. To illustrate the flexibility of the proposed method, visual outputs from diverse areas are demonstrated. Computational performance data are also provided to demonstrate the method’s efficiency. Results indicate that when large matrices are processed, computations using GPU are two to three hundred times faster than the identical algorithms using CPU
Generalized Relativistic Meson Wave Function
We study the most general, relativistic, constituent meson
wave function within a new covariant framework. We find that by including a
tensor wave function component, a pure valence quark model is now capable of
reproducing not only all static pion data (, )
but also the distribution amplitude, form factor , and structure
functions. Further, our generalized spin wave function provides a much better
detailed description of meson properties than models using a simple
relativistic extension of the nonrelativistic wave function.Comment: 17 pages, REXTeX 3.0 file, (uuencoded postscript files of 8 figures
appended
Ions in mixed dielectric solvents: density profiles and osmotic pressure between charged interfaces
The forces between charged macromolecules, usually given in terms of osmotic
pressure, are highly affected by the intervening ionic solution. While in most
theoretical studies the solution is treated as a homogeneous structureless
dielectric medium, recent experimental studies concluded that, for a bathing
solution composed of two solvents (binary mixture), the osmotic pressure
between charged macromolecules is affected by the binary solvent composition.
By adding local solvent composition terms to the free energy, we obtain a
general expression for the osmotic pressure, in planar geometry and within the
mean-field framework. The added effect is due to the permeability inhomogeneity
and nonelectrostatic short-range interactions between the ions and solvents
(preferential solvation). This effect is mostly pronounced at small distances
and leads to a reduction in the osmotic pressure for macromolecular separations
of the order 1--2 nm. Furthermore, it leads to a depletion of one of the two
solvents from the charged macromolecules (modeled as planar interfaces).
Lastly, by comparing the theoretical results with experimental ones, an
explanation based on preferential solvation is offered for recent experiments
on the osmotic pressure of DNA solutions.Comment: 13 pages, 8 figure
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