2,870 research outputs found
Guidelines for Economic Evaluation of Public Sector Water Resource Projects
Water development plays an important role in the economy of states and regions. However, procedures for estimating the expected net worth of proposed projects have never been simple, and results have rarely been without controversy. This report presents some guidelines for the application of economic evaluation procedures in project analysis of public sector water development in North Dakota. A brief history of North Dakota water development and two case studies of North Dakota water projects are included in this report.Resource /Energy Economics and Policy,
Missouri River Water Use in North Dakota
Resource /Energy Economics and Policy,
Next generation sequencing analysis reveals a relationship between rDNA unit diversity and locus number in Nicotiana diploids
© 2012 Matyášek et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative
Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly cited
A Study of the SP Geophysical Technique in a Campus Setting
The self potential (SP) method is a simple and inexpensive geophysical surveying technique, which involves measuring electrical potentials on the surface due to charge separations in the subsurface. These charge separations can arise from a number of different physical and electrochemical processes, and hence interpretations tend to be qualitative. Small anomalies are typically neglected as transient, inexplicable, or uninteresting. In contrast, large negative anomalies associated with ore bodies are noted for their constancy. In this study, an area on the campus of Memorial University was repeatedly surveyed in order to determine which natural and anthropogenic features generated SP anomalies, and whether these anomalies were constant or transient. We found anomalies associated with a building, a buried metallic pipe, trees, and subtler ground variations. The locations of anomalies, both large and small, were notably unvarying over a period of days and weeks. The building always generated a significant negative anomaly, but the sign of other anomalies (including that associated with the pipe) and the magnitude of all anomalies varied with time. In a second area dominated by a shallow sewer pipe, SP data allowed modeling of the burial depth and charge distribution of the pipe. Our results show that SP can be a useful and reliable method for shallow ground surveys, but that the time-varying nature of both sign and magnitude of small to moderate anomalies should be taken into account in data collection and interpretation.
Résumé
La méthode des potentiels spontanés est une technique d’exécution de levés géophysiques simple et peu dispendieuse consistant à mesurer les potentiels électriques à la surface liés aux séparations des charges dans le sous-sol. Ces séparations des charges peuvent découler d’un certain nombre de processus physiques et électrochimiques différents, de sorte que les interprétations données ont tendance à être qualitatives. On néglige généralement les petites anomalies, les considérant comme des anomalies transitoires, inexplicables ou peu intéressantes. En revanche, on note les anomalies négatives poussées qui sont associées aux corps minéralisés en raison de leur constance. Dans le cadre de cette étude, on a réalisé des levés répétés dans un secteur du campus de l’Université Memorial pour déterminer quelles particularités naturelles et artificielles produisaient des anomalies des PS et si ces anomalies étaient constantes ou transitoires. Nous avons découvert des anomalies associées à un bâtiment, à un tuyau en métal enfoui, à des arbres et à des irrégularités du terrain plus subtiles. Fait remarquable, les emplacements des anomalies, tant prononcées que minimes, n’ont pas changé au cours d’une période de plusieurs jours et semaines. Le bâtiment a toujours produit une anomalie négative marquée, mais le signal d’autres anomalies (notamment celle associée au tuyau) et la magnitude de toutes les anomalies ont varié au fil du temps. Dans un second secteur où était surtout présent un tuyau d’égout peu profond, les données des PS ont permis la modélisation de la profondeur d’enfouissement et de la distribution des charges du tuyau. Nos résultats révèlent que la polarisation spontanée peut s’avérer une méthode utile et fiable pour les levés terrestres peu profonds, mais qu’il faudrait tenir compte de la nature variable des signaux et de la magnitude des anomalies minimes à moyennes lors de la collecte et de l’interprétation des données.
[Traduit par la redaction
Heavy Quarkonia Production in p+p Collisions from the PHENIX Experiment
Quarkonia provide a sensitive probe of the properties of the hot dense medium
created in high energy heavy ion collisions. Hard scattering processes result
in the production of heavy quark pairs that interact with the collision medium
during hadronization. These in-medium interactions convey information about the
fundamental properties of the medium itself and can be used to examine the
modification of the QCD confining potential in the collision environment.
Baseline measurements from p+p and d+Au collision systems are used to
distinguish cold nuclear matter effects while measurements from heavy ion
collision systems are used to quantify in-medium effects. The PHENIX experiment
has the capability of detecting heavy quarkonia at via the
decay channel and at via the decay channel.
Recent runs have resulted in the collection of high statistics p+p data sets
that provide an essential baseline reference for heavy ion measurements and
allow for further critical evaluation of heavy quarkonia production mechanisms.
The latest PHENIX results for the production of the in p+p collisions
are presented and future prospects for , and
measurements are discussed.Comment: 4 pages, 2 figures, Proceedings for Quark Matter 200
Optical Observations of the Binary Millisecond Pulsars J2145-0750 and J0034-0534
We report on optical observations of the low-mass binary millisecond pulsar
systems J0034-0534 and J2145-0750. A faint (I=23.5) object was found to be
coincident with the timing position of PSR J2145-0750. While a galaxy or
distant main-sequence star cannot be ruled out, its magnitude is consistent
with an ancient white dwarf, as expected from evolutionary models. For PSR
J0034-0534 no objects were detected to a limiting magnitude of R=25.0,
suggesting that the white dwarf in this system is cold. Using white dwarf
cooling models, the limit on the magnitude of the PSR J0034-0534 companion
suggests that at birth the pulsar in this system may have rotated with a period
as short as 0.6 ms. These observations provide further evidence that the
magnetic fields of millisecond pulsars do not decay on time scales shorter than
1 Gyr.Comment: 6 pages, uuencoded, gz -9 compressed postscript, accepted by ApJ
Transverse energy distributions and production in Pb+Pb collisions
We have analyzed the latest NA50 data on transverse energy distributions and
suppression in Pb+Pb collisions. The transverse energy distribution
was analysed in the geometric model of AA collisions. In the geometric model,
fluctuations in the number of NN collisions at fixed impact parameter are taken
into account. Analysis suggests that in Pb+Pb collisions, individual NN
collisions produces less , than in other AA collisions. The nucleons are
more transparent in Pb+Pb collisions. The transverse energy dependence of the
suppression was obtained following the model of Blaizot et al, where
charmonium suppression is assumed to be 100% effective above a threshold
density. With fluctuations in number of NN collisions taken into account, good
fit to the data is obtained, with a single parameter, the threshold density.Comment: Revised version with better E_T fit. 4 pages, 2 figure
Mega-sized pericentromeric blocks of simple telomeric repeats and their variants reveal patterns of chromosome evolution in ancient Cycadales genomes
Simple telomeric repeats composed of six to seven iterating nucleotide units are important sequences typically found at the ends of chromosomes. Here we analyzed their abundance and homogeneity in 42 gymnosperm (29 newly sequenced), 29 angiosperm (one newly sequenced), and eight bryophytes using bioinformatics, conventional cytogenetic and molecular biology approaches to explore their diversity across land plants. We found more than 10 000-fold variation in the amounts of telomeric repeats among the investigated taxa. Repeat abundance was positively correlated with increasing intragenomic sequence heterogeneity and occurrence at non-telomeric positions, but there was no correlation with genome size. The highest abundance/heterogeneity was found in the gymnosperm genus Cycas (Cycadaceae), in which megabase-sized blocks of telomeric repeats (i.e., billions of copies) were identified. Fluorescent in situ hybridization experiments using variant-specific probes revealed canonical Arabidopsis-type telomeric TTTAGGG repeats at chromosome ends, while pericentromeric blocks comprised at least four major telomeric variants with decreasing abundance: TTTAGGG>TTCAGGG >TTTAAGG>TTCAAGG. Such a diversity of repeats was not found in the sister cycad family Zamiaceae or in any other species analyzed. Using immunocytochemistry, we showed that the pericentromeric blocks of telomeric repeats overlapped with histone H3 serine 10 phosphorylation signals. We show that species of Cycas have amplified their telomeric repeats in centromeric and telomeric positions on telocentric chromosomes to extraordinary high levels. The ancestral chromosome number reconstruction suggests their occurrence is unlikely to be the product of ancient Robertsonian chromosome fusions. We speculate as to how the observed chromosome dynamics may be associated with the diversification of cycads.This project was supported by the Czech Academy of Science, Czech Science Foundation (22-16826S), Czech National Infrastructure for Biological data (ELIXIR CZ, LM2018131), NERC and China Scholarship Council (CSC). JP benefited from a Ramón y Cajal grant Ref: RYC-2017-2274 funded by MCIN/AEI/INTRODUCTION
RESULTS
Identification and quantification of telomeric repeats in high-throughput reads
In silico identification of telomeric repeat variants
Southern blot hybridization analysis of telomeric variants
Identification of cycad centromeres by immunostaining of chromatin
FISH analysis of telomeric variants
Evolution of chromosome numbers and genome sizes across cycads
DISCUSSION
Variable abundance of telomeric repeats in plant genomes
Origin of telomeric repeat variants in cycad genomes
Epigenetic modification of telomeric repeats
Chromosome evolution in cycads
CONCLUSION
EXPERIMENTAL PROCEDURES
Plant material
DNA isolation and Illumina sequencing
Estimation of telomeric repeats abundance and diversity from high-throughput sequencing data
Ancestral chromosome and genome size reconstruction
Southern blot hybridization and DNA methylation analysis
DNA probe preparation for FISH and southern blotting
FISH
Immunohistochemical staining of chromosomes
ACKNOWLEDGEMENTS
Author CONTRIBUTION
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