1,233 research outputs found
New tool gauges impact of exchange rates on states
States with relatively more employment tied to international trade are increasingly likely to be sensitive to exchange rate movements, and face sharply different effective exchange rate shifts, often provoked by economic or financial crises. ; Analysts need a tool to more effectively gauge the sometimes varied impact of exchange rate movements on states. In this article, we introduce a measure that compares the value of the dollar against the currencies of countries with which each of the 50 states trade--the real trade-weighted value of the dollar (RTWVD) index. ; To assess the impact of exchange rates on states, the RTWVD weights the U.S. dollar exchange rate with various countries based on a state's share of exports. It is a "real" measure because it adjusts the exchange rate for different rates of inflation. The index will allow analysts to more precisely identify the exchange rates that most affect a state's economy.International trade ; Foreign exchange rates ; Exports
Z-graded differential geometry of quantum plane
In this work, the Z-graded differential geometry of the quantum plane is
constructed. The corresponding quantum Lie algebra and its Hopf algebra
structure are obtained. The dual algebra, i.e. universal enveloping algebra of
the quantum plane is explicitly constructed and an isomorphism between the
quantum Lie algebra and the dual algebra is given.Comment: 17 page
A square root of the harmonic oscillator
Allowing for the inclusion of the parity operator, it is possible to
construct an oscillator model whose Hamiltonian admits an EXACT square root,
which is different from the conventional approach based on creation and
annihilation operators. We outline such a model, the method of solution and
some generalizations.Comment: RevTex, 10 pages in preprint form, no figure
Efficient estimation of AUC in a sliding window
In many applications, monitoring area under the ROC curve (AUC) in a sliding
window over a data stream is a natural way of detecting changes in the system.
The drawback is that computing AUC in a sliding window is expensive, especially
if the window size is large and the data flow is significant.
In this paper we propose a scheme for maintaining an approximate AUC in a
sliding window of length . More specifically, we propose an algorithm that,
given , estimates AUC within , and can maintain this
estimate in time, per update, as the window slides.
This provides a speed-up over the exact computation of AUC, which requires
time, per update. The speed-up becomes more significant as the size of
the window increases. Our estimate is based on grouping the data points
together, and using these groups to calculate AUC. The grouping is designed
carefully such that () the groups are small enough, so that the error stays
small, () the number of groups is small, so that enumerating them is not
expensive, and () the definition is flexible enough so that we can
maintain the groups efficiently.
Our experimental evaluation demonstrates that the average approximation error
in practice is much smaller than the approximation guarantee ,
and that we can achieve significant speed-ups with only a modest sacrifice in
accuracy
Characterization of a human liver carboxylesterase (hCE-1) that catalyzes the hydrolysis of cocaine to benzoylecgonine and the formation of cocaethylene from alcohol and cocaine
This document only includes an excerpt of the corresponding thesis or dissertation. To request a digital scan of the full text, please contact the Ruth Lilly Medical Library's Interlibrary Loan Department ([email protected])
Representation-theoretic derivation of the Temperley-Lieb-Martin algebras
Explicit expressions for the Temperley-Lieb-Martin algebras, i.e., the
quotients of the Hecke algebra that admit only representations corresponding to
Young diagrams with a given maximum number of columns (or rows), are obtained,
making explicit use of the Hecke algebra representation theory. Similar
techniques are used to construct the algebras whose representations do not
contain rectangular subdiagrams of a given size.Comment: 12 pages, LaTeX, to appear in J. Phys.
Characterization of actinomycetes antagonistic to Phytophthora fragariae var. rubi, the causal agent of raspberry root rot
Onze souches d'actinomycetes ayant la capacité de protéger les plants de framboisiers (Rubus strigosus) contre les infections causées par les Phytophthora ont été caractérisées. Il a été montré que toutes les souches appartenaient au genre Streptomyces. Deux souches (EF-34 et EF-76) croissaient à 4, 15 et 30°C sur un milieu V8 agar dont le pH avait été ajusté entre 5 et 9. Sept souches dont EF-34 et EF-76 pouvaient hydrolyser les parois cellulaires de Phytophthora et inhiber la croissance du champignon à 15°C et à des pH variant entre 5 et 9. Toutes les souches inhibaient la croissance du P. fragariae var. rubi et du Pythium ultimum. La croissance d'autres espèces fongiques et de bactéries à Gram négatif n'était inhibée qu'en présence de trois souches (EF-14, EF-72 et EF-76). Les onze actinomycetes antagonistes ont été classés en quatre groupes selon leur résistance à divers pesticides utilisés pour protéger les cultures de framboisiers. La souche EF-76 a été caractérisée plus en détail. Cette souche a été identifiée comme étant le Streptomyces hygroscopicus var. geldanus, et produisait l'antibiotique geldanamycine.Eleven actinomycete strains that were previously shown to protect raspberry (Rubus strigosus) plants against Phytophthora infection were characterized. all were shown to belong to the genus Streptomyces. Two strains (EF-34 and EF-76) grew at 4, 15 and 30°C on V8 agar between pHs 5 to 9. Seven strains including EF-34 and EF-76 had both the ability to hydrolyze Phytophthora cell walls and to inhibit Phytophthora growth at 15°C between pHs 5 to 9. all actinomycetes inhibited the growth of P. fragariaevar. rubi and of Pythium ultimum. The growth of other fungal species and of Gram-negative bacteria was inhibited only in the presence of three strains (EF-14, EF-72, and EF-76). The eleven antagonistic actinomycetes were classified into four groups with regard to their resistance to various pesticides used to protect raspberry crops. Strain EF-76 was further characterized. This strain was identified as Streptomyceshygroscopicus var. geldanus, and it was shown to produce geldanamycin, a known antibiotic
Lixiviação de íons potássio, cálcio e magnésio para determinação do vigor em sementes de milho doce.
O teste de lixiviação de íons de potássio, cálcio e magnésio é baseado na integridade das membranas celulares das sementes, sendo considerado um procedimento rápido para a avaliação do vigor em sementes de várias espécies. Porém, para sementes de milho doce não se têm informações necessárias para a validação deste procedimento. Com isso, o trabalho teve como objetivo obter informações que permitam o aperfeiçoamento dos testes de lixiviação de potássio, cálcio e magnésio para a avaliação do vigor em sementes de milho doce. Foram utilizados 14 lotes de sementes de milho doce de duas cultivares, BR-401 e BR-402. O delineamento utilizado foi inteiramente casualizado com três repetições. A qualidade fisiológica das sementes foi avaliada por meio dos testes de germinação, condutividade elétrica, emergência a campo, lixiviação de potássio, de cálcio e de magnésio. Os testes de lixiviação de potássio e magnésio foram eficientes na avaliação do vigor em sementes de milho doce. A condutividade elétrica apresentou correlação negativa com a emergência de plântulas e positiva com a lixiviação de íons de potássio e magnésio
Biogeochemical responses to late-winter storms in the Sargasso Sea, III—Estimates of export production using 234Th:238U disequilibria and sediment traps
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 Deep Sea Research Part I: Oceanographic Research Papers 56 (2009): 875-891, doi:10.1016/j.dsr.2009.01.008.Direct measurements of new production and carbon export in the subtropical
North Atlantic Ocean appear to be too low when compared to geochemical based
estimates. It has been hypothesized that episodic inputs of new nutrients into surface
water via the passage of mesoscale eddies or winter storms may resolve at least some of
this discrepancy. Here, we investigated particulate organic carbon (POC), particulate
organic nitrogen (PON), and biogenic silica (BSiO2) export using a combination of water
column 234Th:238U disequilibria and free-floating sediment traps during and immediately
following two weather systems encountered in February and March 2004. While these
storms resulted in a 2-4 fold increase in mixed layer NO3 inventories, total chlorophyll a
and an increase in diatom biomass, the systems was dominated by generally low
234Th:238U disequilibria, suggesting limited particle export. Several 234Th models were
tested, with only those including non-steady state and vertical upwelling processes able to
describe the observed 234Th activities. Although upwelling velocities were not measured
directly in this study, the 234Th model suggests reasonable rates of 2.2 to 3.7 m d-1.
Given the uncertainties associated with 234Th derived particle export rates and
sediment traps, both were used to provide a range in sinking particle fluxes from the
upper ocean during the study. 234Th particle fluxes were determined applying the more
commonly used steady state, 1-dimensional model with element/234Th ratios measured in
sediment traps. Export fluxes at 200 m ranged from 1.91 ± 0.20 to 4.92 ± 1.22 mmol C
m-2 d-1, 0.25 ± 0.08 to 0.54 ± 0.09 mmol N m-2 d-1, and 0.22 ± 0.04 to 0.50 ± 0.06 mmol
Si m-2 d-1. POC export efficiencies (Primary Production/Export) were not significantly
different from the annual average or from time periods without storms, although absolute
POC fluxes were elevated by 1-11%. This increase was not sufficient, however, to
resolve the discrepancy between our observations and geochemical based estimates of
particle export. Comparison of PON export rates with simultaneous measurements of
NO3
- uptake derived new production rates, suggested that only a fraction, < 35%, of new
production was exported as particles to deep waters during these events. Measured bSiO2
export rates were more than a factor of two higher (p < 0.01) than the annual average,
with storm events contributing as much as 50% of annual bSiO2 export in the Sargasso
Sea. Furthermore it appears that 65 - 95% (average 86 ± 14%) of the total POC export
measured in this study was due to diatoms.
Combined these results suggest that winter storms do not significantly increase
POC and PON export to depth. Rather, these storms may play a role in the export of
bSiO2 to deep waters. Given the slower remineralization rates of bSiO2 relative to POC
and PON, this transport may, over time, slowly decrease water column silicate
inventories, and further drive the Sargasso Sea towards increasing silica limitation.
These storm events may further affect the quality of the POC and PON exported given
the large association of this material with diatoms during these periods.This study was funded by the National Science Foundation (Chemical
Oceanography Grants OCE-0244612 and OCE-0241645)
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