122 research outputs found
Sovereign Immunity for Russia\u27s Rocket Engines? Enforcing the Yukos Award
In 2003 Yukos Oil Company was once the largest oil company in Russia, and its oligarch CEO was Russia’s richest man. By 2007 Yukos had been dissolved, its CEO arrested, and its assets acquired by Russian state oil giants Rosneft and Gazprom. The fall of Yukos triggered what may be the largest arbitral dispute of all time. In 2014, the former shareholders of Yukos successfully won a $50 billion award against Russia for violations of the Energy Charter Treaty – by far the largest in history. Now the shareholders need to collect. This Note examines how Yukos could enforce its award by attaching high-value Russian government assets in the United States, in particular the RD-180/181 engines used to power the Atlas V and Antares rockets
Investigation of Peltier Devices for Refrigeration
The purpose of our project was to characterize Peltier devices and determine if they were good candidates toward inexpensive off-grid solar powered refrigeration in poor countries. We measured the rate of cooling with a constant temperature thermal sink for different current inputs. Through numerous experiments we calculated the coefficient of performance for two different thermoelectric coolers (TECs) through a range of temperature differentials. In addition, we found the lowest temperature these Peltier chips could reach so that we could test the accuracy of the information provided by the manufacturers spec sheets. Overall the data gathered through our research is compelling toward the creation of TEC-driven refrigeration
Exoplanet Transit Spectroscopy Using WFC3: WASP-12 b, WASP-17 b, and WASP-19 b
We report analysis of transit spectroscopy of the extrasolar planets WASP-12
b, WASP-17 b, and WASP-19 b using the Wide Field Camera 3 on the HST. We
analyze the data for a single transit for each planet using a strategy similar
in certain aspects to the techniques used by Berta et al. (2012), but we extend
their methodology to allow us to correct for channel- or wavelength-dependent
instrumental effects by utilizing the band-integrated time series and
measurements of the drift of the spectrum on the detector over time. We achieve
almost photon-limited results for individual spectral bins, but the
uncertainties in the transit depth for the the band-integrated data are
exacerbated by the uneven sampling of the light curve imposed by the orbital
phasing of HST's observations. Our final transit spectra for all three objects
are consistent with the presence of a broad absorption feature at 1.4 microns
potentially due to water. However, the amplitude of the absorption is less than
that expected based on previous observations with Spitzer, possibly due to
hazes absorbing in the NIR or non-solar compositions. The degeneracy of models
with different compositions and temperature structures combined with the low
amplitude of any features in the data preclude our ability to place unambiguous
constraints on the atmospheric composition without additional observations with
WFC3 to improve the S/N and/or a comprehensive multi-wavelength analysis.Comment: 20 pages, 21 figures. Accepted for publication in ApJ. Figure and
table positioning is preliminary and subject to change prior to final
publicatio
Kokkos-enhanced ExaMPI
Kokkos provides in-memory advanced data structures, concurrency, and algorithm to support advanced C++ parallel programming. MPI provides the most widely used message passing model for inter-node communication. Many programmers use both Kokkos and the Message Passing Interface (MPI) together. In this thesis, Kokkos is integrated within an MPI implementation to obtain performance and functionality benefits both for the MPI itself, and for applications that use both Kokkos+MPI. For instance, it will be possible in this model to pass first-class Kokkos objects directly to extended C++-based MPI APIs. In particular, efforts to achieve this type of integrated model is expressed using ExaMPI, a C++17-based subset implementation of MPI-4 developed at UTC with collaborators. Working with C++-friendly APIs, and Kokkos extensions, examples of the benefits of functionality and performance are shown. We explain why direct use of Kokkos within the certain parts of the MPI implementation are crucial to getting added performance in addition to expressivity. We also motivate why making Kokkos memory spaces visible to the MPI implementation generalizes the idea of “CPU memory” and “GPU memory” in ways that provide for further optimizations in heterogeneous Exascale architectures. Besides showing the current state of the prototype, we describe future goals, and show how these mesh both with a possible future C++ API for MPI-5 as well as the potential for accelerating MPI on architectures that incorporate accelerators
Kokkos-Enhanced ExaMPI: Modern Parallel Programming for Exascale
Kokkos provides in-memory advanced data structures, concurrency, and algorithm to support performance portable C++ parallel pro- gramming across CPUs and GPUs. MPI provides the most widely used message passing model for inter-node communication. Many programmers use both Kokkos and the Message Passing Interface (MPI) together. In this thesis, Kokkos is integrated within an MPI im- plementation to obtain performance and functionality benefits both for the MPI itself, and for applications that use both Kokkos+MPI. For instance, it will be possible in this model to pass first-class Kokkos objects directly to extended C++-based MPI APIs. In particular, efforts to achieve this type of integrated model is expressed using ExaMPI, a C++17-based subset implementation of MPI-4 developed at UTC with collaborators. Working with C++- friendly APIs, and Kokkos extensions, examples of the benefits of functionality and performance are shown. We explain why direct use of Kokkos within the certain parts of the MPI implementation are crucial to getting added performance in addition to expressivity. We also motivate why making Kokkos memory spaces visible to the MPI implementation generalizes the idea of “CPU memory” and “GPU memory” in ways that provide for further optimizations in heterogeneous Exascale architectures. Besides showing the current state of the prototype, we describe future goals, and show how these mesh both with a possible future C++ API for MPI-5 as well as the potential for accelerating MPI on architectures that incorporate accelerator
Alternative Fuel Sources for Radioisotope Thermoelectric Generators
With Pu-238 in short supply, it is necessary to investigate other potential fuel sources that may
be suitable for powering radioisotope thermoelectric generators (RTGs). This report has
investigated several candidate isotopes based on their power output, decay products, half-lives,
shielding requirements, availability and ability to be isolated. Through manipulation of the
SCALE modeling program, the feasibility of using transuranic radioisotopes found in spent fuel
was thoroughly examined. In addition to examining the use of single isotopes, the possibility of
selecting an isotope that will decay into another feasible isotope will be explored. This report
attempts to identify isotopes that are suitable alternatives to Pu-238 that both fulfill the power
requirements of deep space missions and stay within the economic constraints associated with
such projects
Ground-state energy of H-: a critical test of triple basis sets
We report an improved variational upper bound for the ground state energy of H- using Hylleraaslike wave functions in the form of a triple basis set having three distinct distance scales. The extended precision DQFUN of Bailey, allowing for 70 decimal digit arithmetic, is implemented to retain sufficient precision. Our result exceeds the previous record [A. M. Frolov, Euro. J. Phys. D 69, 132 (2015)], indicating that the Hylleraas triple basis set exhibits comparable convergence to the widely used pseudorandom all-exponential basis sets, but the numerical stability against roundoff error is much better. It is argued that the three distance scales have a clear physical interpretation. The new variational bound is -0.527 751 016 544 377 196 590 814 469 a.u
Detection of Giardia and helminths in Western Europe at local K9 (canine) sites (DOGWALKS Study)
Background
Intestinal parasite contamination from infected dogs can place other dogs and humans at risk. A study was initiated to estimate the prevalence of canine intestinal parasitism by collecting fecal samples in cities across Western Europe.
Methods
Fresh fecal samples were collected from 2469 dogs visiting 164 parks in 33 cities across 12 countries. Each owner responded to a questionnaire focusing on their dog’s signalment and recent anthelmintic treatment history. The collected samples were examined for hookworms, whipworms, ascarids and Giardia using a coproantigen diagnostic immunoassay and microscopy following centrifugal flotation.
Results
Nematodes or Giardia were detected in at least one sample from 100% of cities and in 93.3% of parks. Nematodes were detected in 57% of parks. Overall, 22.8% of dogs tested positive for an intestinal parasite, with Giardia being the most commonly identified parasites (17.3% of dogs, 83.5% of parks). For nematode infection, 7.6% of all dogs tested positive, with 9.9% of dogs aged 1 month had passed since the previous dose.
Conclusions
The prevalence estimates of intestinal parasite infections in dogs reported here highlight the need for owner education concerning guidelines for regular testing and treatment, even in older dogs. Failure to adhere to guidelines can result in ongoing transmission of these infections, including those with zoonotic potential. Combining coproantigen immunoassay with centrifugal flotation for diagnostic testing and regular anthelmintic treatment are important measures for ensuring optimal intestinal parasite control
Dynamics and Formation of the Near-Resonant K2-24 System: Insights from Transit-Timing Variations and Radial Velocities
While planets between the size of Uranus and Saturn are absent within the
Solar System, the star K2-24 hosts two such planets, K2-24b and c, with radii
equal to and , respectively. The two planets have orbital
periods of 20.9 days and 42.4 days, residing only 1% outside the nominal 2:1
mean-motion resonance. In this work, we present results from a coordinated
observing campaign to measure planet masses and eccentricities that combines
radial velocity (RV) measurements from Keck/HIRES and transit-timing
measurements from K2 and Spitzer. K2-24b and c have low, but non-zero,
eccentricities of . The low observed eccentricities
provide clues regarding the formation and dynamical evolution of K2-24b and
K2-24c, suggesting that they could be the result of stochastic gravitational
interactions with a turbulent protoplanetary disk, among other mechanisms.
K2-24b and c are and , respectively; K2-24c is 20%
less massive than K2-24b, despite being 40% larger. Their large sizes and low
masses imply large envelope fractions, which we estimate at
and . In particular, K2-24c's large envelope presents an
intriguing challenge to the standard model of core nucleated accretion that
predicts the onset of runaway accretion when .Comment: 14 pages, 9 figures, 2 tables, accepted to A
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