1,541 research outputs found
Fruitless, Doublesex And The Genetics Of Social Behavior In Drosophila Melanogaster
Two genes coding for transcription factors, fruitless and doublesex, have been suggested to play important roles in the regulation of sexually dimorphic patterns of social behavior in Drosophila melanogaster. The generalization that fruitless specified the development of the nervous system and doublesex specified non-neural tissues culminated with claims that fruitless was both necessary and sufficient to establish sex-specific patterns of behavior. Several recent articles refute this notion, however, demonstrating that at a minimum, both fruitless and doublesex are involved in establishing sexually dimorphic features of neural circuitry and behavior in fruit flies
Transforming U.S. Particle Physics Education: A Snowmass 2021 Study
The pursuit of knowledge in particle physics requires constant learning. As
new tools become available, new theories are developed, and physicists search
for new answers with ever-evolving methods. However, it is the case that formal
educational systems serve as the primary training grounds for particle
physicists. Graduate school (and undergraduate school to a lesser extent) is
where researchers learn most of the technical skills required for research,
develop scientific problem-solving abilities, learn how to establish themselves
in their field, and begin developing their career. It is unfortunate, then,
that the skills gained by physicists during their formal education are often
mismatched with the skills actually required for a successful career in
physics. We performed a survey of the U.S. particle physics community to
determine the missing elements of graduate and undergraduate education and to
gauge how to bridge these gaps. In this contributed paper, part of the 2021-22
Snowmass Community Planning Exercise, we report the results of this survey. We
also recommend several specific community actions to improve the quality of
particle physics education; the "community" here refers to physics departments,
national labs, professional societies, funding agencies, and individual
physicists.Comment: contribution to Snowmass 202
Simulation and observations of stratospheric aerosols from the 2009 Sarychev volcanic eruption
We used a general circulation model of Earth’s climate to conduct simulations of the 12-16 June 2009 eruption of Sarychev volcano (48.1°N, 153.2°E). The model simulates the formation and transport of the stratospheric sulfate aerosol cloud from the eruption and the resulting climate response. We compared optical depth results from these simulations with limb scatter measurements from the Optical Spectrograph and InfraRed Imaging System (OSIRIS), in situ measurements from balloon-borne instruments lofted from Laramie, Wyoming (41.3°N, 105.7°W), and five lidar stations located throughout the Northern Hemisphere. The aerosol cloud covered most of the Northern Hemisphere, extending slightly into the tropics, with peak backscatter measured between 12 and 16 km in altitude. Aerosol concentrations returned to near background levels by Spring, 2010. After accounting for expected sources of discrepancy between each of the data sources, the magnitudes and spatial distributions of aerosol optical depth due to the eruption largely agree. In conducting the simulations, we likely overestimated both particle size and the amount of SO2 injected into the stratosphere, resulting in modeled optical depth values that were a factor of 2-4 too high. Model results of optical depth due to the eruption show a peak too late in high latitudes and too early in low latitudes, suggesting a problem with stratospheric circulation in the model. The model also shows a higher annual decay rate in optical depth than is observed, showing an inaccuracy in seasonal deposition rates. The modeled deposition rate of sulfate aerosols from the Sarychev eruption is higher than the rate calculated for aerosols from the 1991 eruption of Mt. Pinatubo
The Validity of Peer Review in a General Medicine Journal
All the opinions in this article are those of the authors and should not be construed to reflect, in any way, those of the Department of Veterans Affairs
Dynamic changes in spatial representation within the posterior parietal cortex in response to visuomotor adaptation
Hemispherically symmetric strategies for stratospheric aerosol injection
Stratospheric aerosol injection (SAI) comes with a wide range of possible design choices, such as the location and timing of the injection. Different stratospheric aerosol injection strategies can yield different climate responses; therefore, understanding the range of possible climate outcomes is crucial to making informed future decisions on SAI, along with the consideration of other factors. Yet, to date, there has been no systematic exploration of a broad range of SAI strategies. This limits the ability to determine which effects are robust across different strategies and which depend on specific injection choices. This study systematically explores how the choice of SAI strategy affects climate responses in one climate model. Here, we introduce four hemispherically symmetric injection strategies, all of which are designed to maintain the same global mean surface temperature: an annual injection at the Equator (EQ), an annual injection of equal amounts of SO2 at 15° N and 15° S (15N+15S), an annual injection of equal amounts of SO2 at 30° N and 30° S (30N+30S), and a polar injection strategy that injects equal amounts of SO2 at 60° N and 60° S only during spring in each hemisphere (60N+60S). We compare these four hemispherically symmetric SAI strategies with a more complex injection strategy that injects different quantities of SO2 at 30° N, 15° N, 15° S, and 30° S in order to maintain not only the global mean surface temperature but also its large-scale horizontal gradients. All five strategies are simulated using version 2 of the Community Earth System Model with the middle atmosphere version of the Whole Atmosphere Community Climate model, version 6, as the atmospheric component, CESM2(WACCM6-MA), with the global warming scenario, Shared Socioeconomic Pathway (SSP)2-4.5. We find that the choice of SAI strategy affects the spatial distribution of aerosol optical depths, injection efficiency, and various surface climate responses. In addition, injecting in the subtropics produces more global cooling per unit injection, with the EQ and the 60N+60S cases requiring, respectively, 59 % and 50 % more injection than the 30N+30S case to meet the same global mean temperature target. Injecting at higher latitudes results in larger Equator-to-pole temperature gradients. While all five strategies restore Arctic September sea ice, the high-latitude injection strategy is more effective due to the SAI-induced cooling occurring preferentially at higher latitudes. These results suggest trade-offs wherein different strategies appear better or worse, depending on which metrics are deemed important.</p
Increasing water cycle extremes in California and in relation to ENSO cycle under global warming
Since the winter of 2013–2014, California has experienced its most severe drought in recorded history, causing statewide water stress, severe economic loss and an extraordinary increase in wildfires. Identifying the effects of global warming on regional water cycle extremes, such as the ongoing drought in California, remains a challenge. Here we analyse large-ensemble and multi-model simulations that project the future of water cycle extremes in California as well as to understand those associations that pertain to changing climate oscillations under global warming. Both intense drought and excessive flooding are projected to increase by at least 50% towards the end of the twenty-first century; this projected increase in water cycle extremes is associated with a strengthened relation to El Niño and the Southern Oscillation (ENSO)—in particular, extreme El Niño and La Niña events that modulate California’s climate not only through its warm and cold phases but also its precursor patterns
Observation of activity prior to dielectric breakdown in liquid xenon with the XeBrA experiment
Maintaining the electric fields necessary for the current generation of noble
liquid time projection chambers (TPCs), with drift lengths exceeding one meter,
requires a large negative voltage applied to their cathode. Delivering such
high voltage is associated with an elevated risk of electrostatic discharge and
electroluminescence, which would be detrimental to the performance of the TPC.
The Xenon Breakdown Apparatus (XeBrA) is a five-liter high-voltage test chamber
built to investigate the factors contributing to high voltage breakdown in
noble liquids. Area scaling and surface finish were observed to be the dominant
factors affecting breakdown. In addition, small electrical activity was
frequently observed during high voltage ramps prior to electrostatic discharge.
The position of breakdowns was reconstructed with a system of high-speed
cameras and good agreement with electric field simulations was found. Based on
the results presented in this work, we recommend that the next generation of
TPCs should not withstand fields larger than 20 kV/cm on the electrode
surfaces.Comment: 29 pages, 13 figures; typo in the author list correcte
- …