4,407 research outputs found
Extratropical Cyclogenesis and Frontal Waves on Mars: Influences on Dust, Weather and the Planet's climate
Between late autumn and early spring, middle and high latitudes on Mars exhibit strong equatortopole mean temperature contrasts (i.e., "baroclinicity"). Data collected during the Viking era and observations from both the Mars Global Surveyor (MGS) and Mars Reconnaissance Orbiter (MRO) indicate that this strong baroclinicity supports vigorous, large-scale eastward traveling weather systems (i.e., transient synoptic periodwaves) [1,2]. For a rapidly rotating, differentially heated, shallow atmosphere such as on Earth and Mars, these large-scale, extratropical weather disturbances are critical components of the global circulation. The wavelike disturbances act as agents in the transport of heat and momentum between low and high latitudes of the planet. Through cyclonic/anticyclonic winds, intense shear deformations, contractions-dilatations in temperature and density, and sharp perturbations amongst atmospheric tracers (i.e., dust, volatiles (e.g., water vapor) and condensates (e.g., water-ice cloud particles)), Mars extratropical weather systems have significant subsynoptic scale ramifications by supporting atmospheric frontal waves (Fig. 1)
Compounding the Results: The Integration of Virtual Worlds With the Semantic Web
Over the past 20 years, governmental use of Web-base information and
technologies has continually expanded taking advantage of the Web's vast, ever-
expanding volumes of browser-accessible information. Now, it infuses two new
technologies, the first one espousing a world where semantic-powered applications
become knowledgeable assistants for Web users. The second new technology takes a
perceivably flat two-dimensional approach to presenting current Web-content and
adds a three-dimensional perspective to the presentation. Welcome to the Semantic
Web as seen through the eyes of a Virtual World participant, an environment where
Web users no longer are browsing for information that is largely static, where Web
users interact through their proxies (avatars) query applications (Web agents)
soliciting them to collect, filter, verify, correlate and present answers to their queries
often in a more visually palatable three-dimensional format. Following a brief
overview of these two technologies, this article presents several of the key force
drivers behind their evolution and the benefits gleaned from their collective use.
Further discussion identifies new methods for visualizing semantic content in virtual
worlds. Finally, as with any technological evolution, the merge of these two
technologies brings on a whole new set of challenges from a Web userÕs perspective
as well as perspectives from technology developers both in academia and
government
Examining Seasonal Trends of the Martian Polar Warming with the NASA Ames Mars Global Climate Model
The presented work focuses on polar warming as a diagnostic of the mean circulation to increase our understanding of processes that control the mean meridional circulation and transport in the Mars middle atmosphere. The NASA Ames Mars Global Climate Model is utilized to isolate physical processes to determine their impact on polar warming and its seasonal trends
Rotational Evolution During Type I X-Ray Bursts
The rotation rates of six weakly-magnetic neutron stars accreting in low-mass
X-ray binaries have most likely been measured by Type I X-ray burst
observations with RXTE. The nearly coherent oscillations detected during the
few seconds of thermonuclear burning are most simply understood as rotational
modulation of brightness asymmetries on the neutron star surface. We show that,
as suggested by Strohmayer and colleagues, the frequency changes of 1-2 Hz
observed during bursts are consistent with angular momentum conservation as the
burning shell hydrostatically expands and contracts. We calculate how vertical
heat propagation through the radiative outer layers of the atmosphere and
convection affect the coherence of the oscillation. We show that the evolution
of the rotational profile depends strongly on whether the burning layers are
composed of pure helium or mixed hydrogen/helium. Our results help explain the
absence (presence) of oscillations from hydrogen-burning (helium-rich) bursts
that was found by Muno and collaborators.
We investigate angular momentum transport within the burning layers and the
recoupling of the burning layers with the star. We show that the
Kelvin-Helmholtz instability is quenched by the strong stratification, and that
mixing between the burning fuel and underlying ashes by the baroclinic
instability does not occur. However, the baroclinic instability may have time
to operate within the differentially rotating burning layer, potentially
bringing it into rigid rotation.Comment: To appear in The Astrophysical Journal; minor corrections made to
tables and figure
Met Receptor Inhibitor SU11274 Localizes in the Endoplasmic Reticulum
We discovered that SU11274, a class I c-Met inhibitor, fluoresces when excited by 488 nm laser light and showed rapid specific accumulation in distinct subcellular compartments. Given that SU11274 reduces cancer cell viability, we exploited these newly identified spectral properties to determine SU11274 intracellular distribution and accumulation in human pancreatic cancer cells. The aim of the studies reported here was to identify organelle(s) to which SU11274 is trafficked. We conclude that SU11274 rapidly and predominantly accumulates in the endoplasmic reticulum
Falling down a flight of stairs: the impact of age and intoxication on injury pattern and severity
Background
Falling down a flight of stairs is a common injury mechanism in major
trauma patients, but little research has been undertaken into the impact of
age and alcohol intoxication on the injury patterns of these patients.
Objectives
The objective of this study was to compare the impact of age and alcohol
intoxication on injury pattern and severity in patients who fell down a flight
of stairs.
Methods
This was a retrospective observational study of prospectively collected
trauma registry data from a major trauma centre in the United Kingdom
comparing older and younger adult patients admitted to the Emergency
Department following a fall down a flight of stairs between July 2012 and
March 2015.
Results
Older patients were more likely to suffer injuries to all body regions, and
sustained more severe injuries to the spine (AIS 2[IQR 2 – 3] vs AIS 2
[IQR 2 – 2] p<0.001). They were also more likely to suffer polytrauma
(23.6% vs 10.6%; p<0.001). Intoxicated patients were more likely to
suffer injuries to the head and neck (42.9% vs 30.5%; p=0.006) and were
significantly younger than sober patients (53 years vs 69 years; p<0.001).
Conclusion
Older patients who fall down a flight of stairs are significantly different
from their younger counterparts, with a different injury pattern and a
greater likelihood of polytrauma. In addition, alcohol intoxication also
affects injury pattern in people who have fallen down a flight of stairs,
increasing the risk of traumatic brain injury. Both age and intoxication
should be considered when managing these patients
Upper Boundary Extension of the NASA Ames Mars General Circulation Model
Extending the NASA Ames Mars General Circulation Model (MGCM) upper boundary will expand our understanding of the connection between the lower and upper atmosphere of Mars through the middle atmosphere. The extension's main requirements is incorporation of Non-local thermodynamic equilibrium (NLTE) heating (visible) and cooling (infrared). NLTE occurs when energy is exchanged more rapidly with the radiation field (or other energy sources) rather than collisions with other molecules. Without NLTE above approximately 80km/approximately 60km in Mars' atmosphere the IR/visible heating rates are overestimated. Currently NLTE has been applied successfully into the 1D RT code and is in progress for the 3D application
- …