1,950 research outputs found
Inhibiting dopamine reuptake blocks the induction of long-term potentiation and depression in the lateral entorhinal cortex of awake rats
Synaptic plasticity in olfactory inputs to the lateral entorhinal cortex may result in lasting changes in the processing of olfactory stimuli. Changes in dopaminergic tone can have strong effects on basal evoked synaptic responses in the superficial layers of the entorhinal cortex, and the current study investigated whether dopamine may modulate the induction of long-term potentiation (LTP) and depression (LTD) in piriform cortex inputs to layer II of the lateral entorhinal cortex in awake rats. Groups of animals were pretreated with either saline or the selective dopamine reuptake inhibitor GBR12909 prior to low or high frequency stimulation to induce LTD or LTP. In saline-treated groups, synaptic responses were potentiated to 122.4 ± 6.4% of baseline levels following LTP induction, and were reduced to 84.5 ± 4.9% following induction of LTD. Changes in synaptic responses were maintained for up to 60 min and returned to baseline levels within 24 h. In contrast, induction of both LTP and LTD was blocked in rats pretreated with GBR12909. Dopaminergic suppression of synaptic plasticity in the entorhinal cortex may serve to restrain activity-dependent plasticity during reward-relevant behavioral states or during processing of novel stimuli
Development of Constructed Wetlands for the Reuse of Wastewat r in Semi-Arid Regions
Hill Air Force Base (AFB), UT, is responsible for the operation and maintenance of the Utah Test and Training Range (UTTR). The range contains waste-water treatment and disposal facilities that consist of two infiltration ponds operated in parallel, followed by an emergency overflow basin that safeguards against unexpectedly high flow rates. A previous evaluation concluded that the existing facilities should be replaced, at a relatively high cost and with no possibility for beneficial water reuse. The U.S. Army Construction Engineering Research Laboratories (USACERL) was requested to further evaluate the system and to identify cost-effective, feasible alternatives. USACERL researchers identified a potential process train that included retention of the existing ponds, use of a constructed wetland for further treatment following the ponds, construction of a small basin following the wetland to improve wildlife habitat, and the possibility of pumping treated effluent back to the built-up portion of Hill AFB for reuse as landscape irrigation
Five Planets Transiting a Ninth Magnitude Star
The Kepler mission has revealed a great diversity of planetary systems and
architectures, but most of the planets discovered by Kepler orbit faint stars.
Using new data from the K2 mission, we present the discovery of a five planet
system transiting a bright (V = 8.9, K = 7.7) star called HIP 41378. HIP 41378
is a slightly metal-poor late F-type star with moderate rotation (v sin(i) = 7
km/s) and lies at a distance of 116 +/- 18 from Earth. We find that HIP 41378
hosts two sub-Neptune sized planets orbiting 3.5% outside a 2:1 period
commensurability in 15.6 and 31.7 day orbits. In addition, we detect three
planets which each transit once during the 75 days spanned by K2 observations.
One planet is Neptune sized in a likely ~160 day orbit, one is sub-Saturn sized
likely in a ~130 day orbit, and one is a Jupiter sized planet in a likely ~1
year orbit. We show that these estimates for the orbital periods can be made
more precise by taking into account dynamical stability considerations. We also
calculate the distribution of stellar reflex velocities expected for this
system, and show that it provides a good target for future radial velocity
observations. If a precise orbital period can be determined for the outer
Jovian planet through future observations, it will be an excellent candidate
for follow-up transit observations to study its atmosphere and measure its
oblateness.Comment: Accepted by ApJL. 12 pages, 6 figures, 2 table
Recommended from our members
Increased threat of tropical cyclones and coastal flooding to New York City during the anthropogenic era
Author Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here by permission of National Academy of Sciences for personal use, not for redistribution. The definitive version was published in Proceedings of the National Academy of Sciences of the United States of America 112 (2015): 12610-12615, doi:10.1073/pnas.1513127112.In a changing climate, future inundation of the United Statesâ Atlantic coast will depend on both storm
surges during tropical cyclones and the rising relative sea-levels on which those surges occur. However,
the observational record of tropical cyclones in the North Atlantic basin is too short (AD 1851-present)
to accurately assess long-term trends in storm activity. To overcome this limitation, we use proxy sealevel
records, and downscale three CMIP5 models to generate large synthetic tropical cyclone data sets
for the North Atlantic basin; driving climate conditions span from AD 850 to AD 2005. We compare preanthropogenic
era (AD 850 â AD 1800) and anthropogenic era (AD 1970 â AD 2005) storm-surge model
results for New York City, exposing links between increased rates of sea-level rise and storm flood
heights. We find that mean flood heights increased by ~1.24 m (due mainly to sea level rise) from ~AD
850 to the anthropogenic era, a result that is significant at the 99% confidence level. Additionally,
changes in tropical cyclone characteristics have led to increases in the extremes of the types of storms
that create the largest storm surges for New York City. As a result, flood risk has greatly increased for
the region; for example, the 500 year return period for a ~2.25 m flood height during the preanthropogenic
era has decreased to ~24.4 years in the anthropogenic era. Our results indicate the
impacts of climate change on coastal inundation, and call for advanced risk management strategies.The authors acknowledge funding for this study from NOAA Grants # 424-18 45GZ and #
NA11OAR4310101 and National Science Foundation award OCE 1458904.2016-03-2
The Robustness of Dark Matter Density Profiles in Dissipationless Mergers
We present a comprehensive series of dissipationless N-body simulations to
investigate the evolution of density distribution in equal-mass mergers between
dark matter (DM) halos and multicomponent galaxies. The DM halo models are
constructed with various asymptotic power-law indices ranging from steep cusps
to core-like profiles and the structural properties of the galaxy models are
motivated by the LCDM paradigm of structure formation. The adopted force
resolution allows robust density profile estimates in the inner ~1% of the
virial radii of the simulated systems. We demonstrate that the central slopes
and overall shapes of the remnant density profiles are virtually identical to
those of the initial systems suggesting that the remnants retain a remarkable
memory of the density structure of their progenitors, despite the relaxation
that accompanies merger activity. We also find that halo concentrations remain
approximately constant through hierarchical merging involving identical systems
and show that remnants contain significant fractions of their bound mass well
beyond their formal virial radii. These conclusions hold for a wide variety of
initial asymptotic density slopes, orbital energies, and encounter
configurations, including sequences of consecutive merger events, simultaneous
mergers of severals ystems, and mergers of halos with embedded cold baryonic
components in the form of disks, spheroids, or both. As an immediate
consequence, the net effect of gas cooling, which contracts and steepens the
inner density profiles of DM halos, should be preserved through a period of
dissipationless major merging. Our results imply that the characteristic
universal shape of DM density profiles may be set early in the evolution of
halos.Comment: Accepted for publication in ApJ, 20 pages, 10 figures, LaTeX (uses
emulateapj.cls
On the size-dependent fatigue behaviour of laser powder bed fusion Ti-6Al-4V
A sample size effect which influences the fatigue behaviour of laser powder bed fusion Ti-6Al-4V is identified and quantified. Two cylindrical samples are considered: â
1.3 mm and â
2.0 mm. The larger specimen demonstrates better fatigue resistance particularly in the high-cycle regime, with the differing surface roughness contributing to this effect. It is also confirmed that processing-induced porosity can compromise the fatigue performance even when the initiation sites are surface defects. The larger contribution of porosity to the fatigue fracture process of the larger specimen results in a higher scatter in the fatigue life. Differences in microstructure do not seem to contribute strongly to the variation in fatigue properties of the two specimens, but we present some evidence that the coarser microstructure of the larger specimen promotes a stronger tolerance to defects and induces more tortuous crack paths which hinders fatigue crack growth
What Is Meant by âReplicationâ and Why Does It Encounter Resistance in Economics?
This paper discusses recent trends in the use of replications in economics. We include the results of recent replication studies that have attempted to identify replication rates within the discipline. These studies generally find that replication rates are relatively low. We then consider obstacles to undertaking replication studies and highlight replication initiatives in psychology and political science, behind which economics appears to lag
Managing Peatland Ecosystem Services: Current UK policy and future challenges in a changing world.
The potential for aquaculture to reduce poverty and control schistosomiasis in CĂŽte dâIvoire (Ivory Coast) during an era of climate change : a systematic review
This work was supported by the Natural Environment Research Council (NERC) via the Belmont Forum: Climate and Health under grant # NE/T013710/1. CLW and GADL were partially supported by US National Science Foundation (NSF) project ICER-2024383. GADL was also partially supported by NSF DEBâ2011179.The development of water management infrastructures, such as dams and canals, are important components of societyâs response to feed a growing human population and to fight climate change. Yet, these changes in land use can also increase the transmission risk for waterborne diseases. Transmission risk associated with artificial reservoirs has been extensively documented for schistosomiasis, a parasitic disease of poverty that infects more than 240 million people worldwide. Over 90% of these cases are in sub-Saharan Africa, a region that is being steadily reshaped by climate change. Controlling the parasiteâs obligate intermediate host snail is key to reducing transmission of this disease. Using commercial aquaculture to farm marketable species which predate upon these snails in vulnerable regions can have multiple positive effects, including the improved socioeconomic and nutritional health of surrounding communities. Here the authors assessed the viability of using the aquaculture of snail predators to simultaneously control schistosomiasis infection rates while alleviating economic and/or nutritional poverty in endemic regions of sub-Saharan Africa. A PRISMA-based 6-step systematic methodology was used to explore the primary literature using the case study of CĂŽte dâIvoire and two native species of snail predator to make evidence-based conclusions on the viability of this method for controlling schistosomiasis. This detailed thematic examination of the literature concluded that using specific approaches and species, aquaculture could be effective in reducing economic poverty and chronic malnourishment along with high levels of schistosomiasis infection. More current species-specific aquaculture data and consumer survey data are, however, needed to determine the economic and logistical effectiveness of farming native snail predators in-country. These and other opportunities for future research are highlighted.Publisher PDFPeer reviewe
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