20 research outputs found
Digital Repository of Mathematical Formulae
The purpose of the NIST Digital Repository of Mathematical Formulae (DRMF) is
to create a digital compendium of mathematical formulae for orthogonal
polynomials and special functions (OPSF) and of associated mathematical data.
The DRMF addresses needs of working mathematicians, physicists and engineers:
providing a platform for publication and interaction with OPSF formulae on the
web. Using MediaWiki extensions and other existing technology (such as software
and macro collections developed for the NIST Digital Library of Mathematical
Functions), the DRMF acts as an interactive web domain for OPSF formulae.
Whereas Wikipedia and other web authoring tools manifest notions or
descriptions as first class objects, the DRMF does that with mathematical
formulae. See http://gw32.iu.xsede.org/index.php/Main_Page
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In vivo photopharmacology with light-activated opioid drugs
Traditional methods for site-specific drug delivery in the brain are slow, invasive, and difficult to interface with recordings of neural activity. Here, we demonstrate the feasibility and experimental advantages of in vivo photopharmacology using "caged" opioid drugs that are activated in the brain with light after systemic administration in an inactive form. To enable bidirectional manipulations of endogenous opioid receptors in vivo, we developed photoactivatable oxymorphone (PhOX) and photoactivatable naloxone (PhNX), photoactivatable variants of the mu opioid receptor agonist oxymorphone and the antagonist naloxone. Photoactivation of PhOX in multiple brain areas produced local changes in receptor occupancy, brain metabolic activity, neuronal calcium activity, neurochemical signaling, and multiple pain- and reward-related behaviors. Combining PhOX photoactivation with optical recording of extracellular dopamine revealed adaptations in the opioid sensitivity of mesolimbic dopamine circuitry in response to chronic morphine administration. This work establishes a general experimental framework for using in vivo photopharmacology to study the neural basis of drug action
Assessing the uncertainties of model estimates of primary productivity in the tropical Pacific Ocean
Author Posting. © Elsevier B.V., 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Journal of Marine Systems 76 (2009): 113-133, doi:10.1016/j.jmarsys.2008.05.010.Depth-integrated primary productivity (PP) estimates obtained from satellite
ocean color based models (SatPPMs) and those generated from biogeochemical ocean
general circulation models (BOGCMs) represent a key resource for biogeochemical and
ecological studies at global as well as regional scales. Calibration and validation of these
PP models are not straightforward, however, and comparative studies show large
differences between model estimates. The goal of this paper is to compare PP estimates
obtained from 30 different models (21 SatPPMs and 9 BOGCMs) to a tropical Pacific PP
database consisting of ~1000 14C measurements spanning more than a decade (1983-
1996). Primary findings include: skill varied significantly between models, but
performance was not a function of model complexity or type (i.e. SatPPM vs. BOGCM);
nearly all models underestimated the observed variance of PP, specifically yielding too
few low PP (< 0.2 gC m-2d-2) values; more than half of the total root-mean-squared
model-data differences associated with the satellite-based PP models might be accounted
for by uncertainties in the input variables and/or the PP data; and the tropical Pacific
database captures a broad scale shift from low biomass-normalized productivity in the
1980s to higher biomass-normalized productivity in the 1990s, which was not
successfully captured by any of the models. This latter result suggests that interdecadal
and global changes will be a significant challenge for both SatPPMs and BOGCMs.
Finally, average root-mean-squared differences between in situ PP data on the equator at
140°W and PP estimates from the satellite-based productivity models were 58% lower
than analogous values computed in a previous PP model comparison six years ago. The
success of these types of comparison exercises is illustrated by the continual modification
and improvement of the participating models and the resulting increase in model skill.This research was supported by a grant from the National Aeronautics and Space Agency
Ocean Biology and Biogeochemistry program (NNG06GA03G), as well as by numerous
other grants to the various participating investigator
Locating Tax Facilities: A Graphics-Based Microcomputer Optimization Model
This paper presents a mathematical model that selects locations for Internal Revenue Service Posts-of-Duty. The system is microcomputer-based and uses menus and graphically displayed zip code maps of IRS districts for interactive inputs and solution outputs. The mathematical model used for this problem is the uncapacitated, fixed charge, location-allocation model which minimizes travel and facility costs, given a specified level of activity. A greedy-interchange heuristic is used to obtain "good" solutions to the problem and is coupled with a lagrangian-relaxation technique providing a measure of how far from optimality the current solution can be. An example with Florida data illustrates the use of the model.uncapacitated facility location, plant location, application to tax service, Lagrangian approach, heuristic algorithm, microcomputer, interactive graphics