3,272 research outputs found
Hydrologic variability related to El Nino in the Pacific Northwest [abstract]
A preliminary statistical analysis was undertaken to evaluate whether the effect of El Nino events is apparent in variables related to hydrologic behavior. Annual precipitation, temperature and streamflow were used for three locations in Oregon representing coastal, Willamette Valley/Cascade and eastern Oregon regions. The mean and variance for periods of El Nino occurrence vs. those with no El Nino were computed. Numerical differences were observed but were not consistent across all stations. The coastal area showed a decrease in mean precipitation and increase in mean streamflow during El Nino events. Other stations showed a positive increase in mean for both precipitation and streamflow for El Nino events. Variance of precipitation was greater in the coastal area but smaller in other areas and vice versa for streamflow during El Nino events. Statistical analyses indicated no significant differences of means, variances or distributions using nonparametric tests for El Nino vs. non-El Nino series
Annual stream flow variability over the western United States [abstract]
EXTRACT (SEE PDF FOR FULL ABSTRACT):
The variability of mean annual streamflow over the western United States is described and related to indices of large scale atmospheric circulation over the Pacific Ocean and western U.S. Principal component analysis reveal [sic] four statistically significant modes of streamflow variability across the region
The Homeostasis Protocol: Avoiding Transaction Coordination Through Program Analysis
Datastores today rely on distribution and replication to achieve improved
performance and fault-tolerance. But correctness of many applications depends
on strong consistency properties - something that can impose substantial
overheads, since it requires coordinating the behavior of multiple nodes. This
paper describes a new approach to achieving strong consistency in distributed
systems while minimizing communication between nodes. The key insight is to
allow the state of the system to be inconsistent during execution, as long as
this inconsistency is bounded and does not affect transaction correctness. In
contrast to previous work, our approach uses program analysis to extract
semantic information about permissible levels of inconsistency and is fully
automated. We then employ a novel homeostasis protocol to allow sites to
operate independently, without communicating, as long as any inconsistency is
governed by appropriate treaties between the nodes. We discuss mechanisms for
optimizing treaties based on workload characteristics to minimize
communication, as well as a prototype implementation and experiments that
demonstrate the benefits of our approach on common transactional benchmarks
ASTAR Flight Test: Overview and Spacing Results
The purpose of the NASA Langley Airborne Spacing for Terminal Arrival Routes (ASTAR) research aboard the Boeing ecoDemonstrator aircraft was to demonstrate the use of NASA's ASTAR algorithm using contemporary tools of the Federal Aviation Administration's Next Generation Air Transportation System (NEXTGEN). EcoDemonstrator is a Boeing test program which utilizes advanced experimental equipment to accelerate the science of aerospace and environmentally friendly technologies. The ASTAR Flight Test provided a proof-of-concept flight demonstration that exercised an algorithmic-based application in an actual aircraft. The test aircraft conducted Interval Management operations to provide time-based spacing off a target aircraft in non-simulator wind conditions. Work was conducted as a joint effort between NASA and Boeing to integrate ASTAR in a Boeing supplied B787 test aircraft while using a T-38 aircraft as the target. This demonstration was also used to identify operational risks to future flight trials for the NASA Air Traffic Management Technology Demonstration expected in 2017
Ten years of invasion: Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) in Britain
1. Harmonia axyridis was first recorded in Britain in 2004. Two subsequent earlier records were received from 2003.
2. The UK Ladybird Survey, a citizen science initiative involving online recording, was launched in 2005 to encourage people across Britain to track the spread of H. axyridis. Tens of thousands of people have provided records of H. axyridis and other species of ladybirds, creating an invaluable dataset for large-scale and long-term research. Declines in the distribution of seven (of eight assessed) native species of ladybird have been demonstrated, and correlated with the arrival of H. axyridis, using the records collated through the UK Ladybird Survey.
3. Experimental research and field surveys have also contributed to our understanding of the ecology of H. axyridis and particularly the process of invasion. Harmonia axyridis arrived in Britain through dispersal and introduction events from regions in which it was deliberately released as a biological control agent. The rapid spread of this species has been attributed to its high natural dispersal capability by means of both flight and anthropogenic transport. A number of factors have contributed to the successful establishment and indeed dominance of this polymorphic species within aphidophagous guilds, including high reproductive capacity, intra-guild predation, eurytopic nature, high resistance to natural enemies within the invaded range, and potentially phenotypic plasticity.
4. The global invasion by H. axyridis and subsequent research on this species has contributed to the general understanding of biological invasions
Traditional hepatoprotective herbal medicine of Koch tribe in the South-West Garo hills district, Meghalaya
312-317Field survey made in 24 villages of the South-West Garo Hills district, Meghalaya, inhabited mainly by the Koch community helped to gather ethnobotanical information concerning 25 medicinal plant species belonging to 24 Angiospermic and 1 Pteridophytic genus under 22 different families that are used as traditional hepatoprotective herbal medicine. Among the different plant parts prescribed for hepatoprotection, fruits are the most frequently used plant part (25%), followed by leaves (21.42%) and then followed by stems, rhizomes, roots and the whole plant which had equal applications (10.71%). Barks (7.14%) and cloves (3.57%) of the medicinal plants were relatively less frequently prescribed plant part for the purpose of hepatoprotection. Regarding the life form of the reported medicinal plants prescribed by the traditional healers, herbs (11 species) were most frequently used, followed by trees (7 species), climbers (3 species), shrubs (2 species) and epiphytes (2 species). All plant parts tested positive for alkaloids
Dynamics of linear polymers in random media
We study phenomenological scaling theories of the polymer dynamics in random
media, employing the existing scaling theories of polymer chains and the
percolation statistics. We investigate both the Rouse and the Zimm model for
Brownian dynamics and estimate the diffusion constant of the center-of-mass of
the chain in such disordered media. For internal dynamics of the chain, we
estimate the dynamic exponents. We propose similar scaling theory for the
reptation dynamics of the chain in the framework of Flory theory for the
disordered medium. The modifications in the case of correlated disordered are
also discussed.Comment: 4 pages, no figure
Detection of water quality changes through optimal tests and reliability of tests
Submitted to Office of Water Research and Technology.Bibliography: page 77.OWRT Project no. B-186-COLO; Grant agreement no. 14-34-0001-8069
Dilepton Yield in Heavy-Ion Collisions with Bose Enhancement of Decay Width
The excess of low invariant mass dilepton yield in heavy ion collisions
arising from reduction in the rho meson mass at finite temperatures is
partially suppressed because of the effect on the width of the rho meson
induced by Bose enhancement, essentially due to emission of pions in a medium
of the pion gas in the central rapidity region. The sensitivity of the effect
on the initial temperature of the hadronic phase is also examined.Comment: Plain latex fil
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