551 research outputs found
Unwind: Interactive Fish Straightening
The ScanAllFish project is a large-scale effort to scan all the world's
33,100 known species of fishes. It has already generated thousands of
volumetric CT scans of fish species which are available on open access
platforms such as the Open Science Framework. To achieve a scanning rate
required for a project of this magnitude, many specimens are grouped together
into a single tube and scanned all at once. The resulting data contain many
fish which are often bent and twisted to fit into the scanner. Our system,
Unwind, is a novel interactive visualization and processing tool which
extracts, unbends, and untwists volumetric images of fish with minimal user
interaction. Our approach enables scientists to interactively unwarp these
volumes to remove the undesired torque and bending using a piecewise-linear
skeleton extracted by averaging isosurfaces of a harmonic function connecting
the head and tail of each fish. The result is a volumetric dataset of a
individual, straight fish in a canonical pose defined by the marine biologist
expert user. We have developed Unwind in collaboration with a team of marine
biologists: Our system has been deployed in their labs, and is presently being
used for dataset construction, biomechanical analysis, and the generation of
figures for scientific publication
An Auditory Go/No-Go Study of Event-Related Potentials in Children with Fetal Alcohol Spectrum Disorders
Greater Trochanteric Pain Syndrome
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135686/1/jum201635112413.pd
Regional and temporal variability of melts during a Cordilleran magma pulse: Age and chemical evolution of the Jurassic arc, eastern Mojave Desert, California
Intrusive rock sequences in the central and eastern Mojave Desert segment of the Jurassic Cordilleran arc of the western United States record regional and temporal variations in magmas generated during the second prominent pulse of Mesozoic continental arc magmatism. U/Pb zircon ages provide temporal control for describing variations in rock and zircon geochemistry that reflect differences in magma source components. These source signatures are discernible through mixing and fractionation processes associated with magma ascent and emplacement. The oldest well-dated Jurassic rocks defining initiation of the Jurassic pulse are a 183 Ma monzodiorite and a 181 Ma ignimbrite. Early to Middle Jurassic intrusive rocks comprising the main stage of magmatism include two high-K calc-alkalic groups: to the north, the deformed 183–172 Ma Fort Irwin sequence and contemporaneous rocks in the Granite and Clipper Mountains, and to the south, the 167–164 Ma Bullion sequence. A Late Jurassic suite of shoshonitic, alkali-calcic intrusive rocks, the Bristol Mountains sequence, ranges in age from 164 to 161 Ma and was emplaced as the pulse began to wane. Whole-rock and zircon trace-element geochemistry defines a compositionally coherent Jurassic arc with regional and secular variations in melt compositions. The arc evolved through the magma pulse by progressively greater input of old cratonic crust and lithospheric mantle into the arc magma system, synchronous with progressive regional crustal thickening
High-Resolution Spectroscopic Study of Extremely Metal-Poor Star Candidates from the SkyMapper Survey
The SkyMapper Southern Sky Survey is carrying out a search for the most
metal-poor stars in the Galaxy. It identifies candidates by way of its unique
filter set that allows for estimation of stellar atmospheric parameters. The
set includes a narrow filter centered on the Ca II K 3933A line, enabling a
robust estimate of stellar metallicity. Promising candidates are then confirmed
with spectroscopy. We present the analysis of Magellan-MIKE high-resolution
spectroscopy of 122 metal-poor stars found by SkyMapper in the first two years
of commissioning observations. 41 stars have [Fe/H] <= -3.0. Nine have [Fe/H]
<= -3.5, with three at [Fe/H] ~ -4. A 1D LTE abundance analysis of the elements
Li, C, Na, Mg, Al, Si, Ca, Sc, Ti, Cr, Mn, Co, Ni, Zn, Sr, Ba and Eu shows
these stars have [X/Fe] ratios typical of other halo stars. One star with low
[X/Fe]
[X/Fe values appears to be "Fe-enhanced," while another star has an extremely
large [Sr/Ba] ratio: >2. Only one other star is known to have a comparable
value. Seven stars are "CEMP-no" stars ([C/Fe] > 0.7, [Ba/Fe] < 0). 21 stars
exhibit mild r-process element enhancements (0.3 <=[Eu/Fe] < 1.0), while four
stars have [Eu/Fe] >= 1.0. These results demonstrate the ability to identify
extremely metal-poor stars from SkyMapper photometry, pointing to increased
sample sizes and a better characterization of the metal-poor tail of the halo
metallicity distribution function in the future.Comment: Minor corrections to text, missing data added to Tables 3 and 4;
updated to match published version. Complete tables included in sourc
Observation of cavitation dynamics in viscous deep eutectic solvents during power ultrasound sonication
Deep Eutectic Solvents (DESs) are a class of ionic liquid with emerging applications in ionometallurgy. The characteristic high viscosity of DESs, however, limit mass transport and result in slow dissolution kinetics. Through targeted application of high-power ultrasound, ionometallurgical processing time can be significantly accelerated. This acceleration is primarily mediated by the cavitation generated in the liquid surrounding the ultrasound source. In this work, we characterise the development of cavitation structure in three DESs of increasing viscosity, and water, via high-speed imaging and parallel acoustic detection. The intensity of the cavitation is characterised in each liquid as a function of input power of a commercially available ultrasonic horn across more than twenty input powers, by monitoring the bubble collapse shockwaves generated by intense, inertially collapsing bubbles. Through analysis of the acoustic emissions and bubble structure dynamics in each liquid, optimal driving powers are identified where cavitation is most effective. In each of the DESs, driving the ultrasonic horn at lower input powers (25%) was associated with greater cavitation performance than at double the driving power (50%)
String Theoretic Bounds on Lorentz-Violating Warped Compactification
We consider warped compactifications that solve the 10 dimensional
supergravity equations of motion at a point, stabilize the position of a
D3-brane world, and admit a warp factor that violates Lorentz invariance along
the brane. This gives a string embedding of ``asymmetrically warped'' models
which we use to calculate stringy (\alpha') corrections to standard model
dispersion relations, paying attention to the maximum speeds for different
particles. We find, from the dispersion relations, limits on gravitational
Lorentz violation in these models, improving on current limits on the speed of
graviton propagation, including those derived from field theoretic loops. We
comment on the viability of models that use asymmetric warping for self-tuning
of the brane cosmological constant.Comment: 20pg, JHEP3; v2 additional references, slight change to intro; v3.
added referenc
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A large proportion of North American net ecosystem production is offset by emissions from harvested products, river/stream evasion, and biomass burning
Diagnostic carbon cycle models produce estimates of net ecosystem production (NEP, the balance of net primary production
and heterotrophic respiration) by integrating information from (i) satellite-based observations of land surface
vegetation characteristics; (ii) distributed meteorological data; and (iii) eddy covariance flux tower observations of
net ecosystem exchange (NEE) (used in model parameterization). However, a full bottom-up accounting of NEE (the
vertical carbon flux) that is suitable for integration with atmosphere-based inversion modeling also includes emissions
from decomposition/respiration of harvested forest and agricultural products, CO₂ evasion from streams and
rivers, and biomass burning. Here, we produce a daily time step NEE for North America for the year 2004 that
includes NEP as well as the additional emissions. This NEE product was run in the forward mode through the CarbonTracker
inversion setup to evaluate its consistency with CO₂ concentration observations. The year 2004 was climatologically
favorable for NEP over North America and the continental total was estimated at 1730± 370 TgC yr
⁻¹ (a
carbon sink). Harvested product emissions (316 ± 80 TgC yr
⁻ ¹), river/stream evasion (158 ± 50 TgC yr
⁻¹), and fire
emissions (142 ± 45 TgC yr
⁻¹) counteracted a large proportion (35%) of the NEP sink. Geographic areas with strong
carbon sinks included Midwest US croplands, and forested regions of the Northeast, Southeast, and Pacific Northwest.
The forward mode run with CarbonTracker produced good agreement between observed and simulated wintertime
CO₂ concentrations aggregated over eight measurement sites around North America, but overestimates of
summertime concentrations that suggested an underestimation of summertime carbon uptake. As terrestrial NEP is
the dominant offset to fossil fuel emission over North America, a good understanding of its spatial and temporal variation
– as well as the fate of the carbon it sequesters ─ is needed for a comprehensive view of the carbon cycle.Keywords: net ecosystem exchange, river evasion, biomass burning, net ecosystem production, atmospheric inversion model, carbon flu
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