350 research outputs found
ArcGIS Digitization of Apollo Surface Traverses
The Apollo surface activities were documented in extraordinary detail, with every action performed by the astronauts while on the surface recorded either in photo, audio, film, or by written testimony [1]. The samples and in situ measurements the astronauts collected while on the lunar surface have shaped our understanding of the geologic history of the Moon, and the earliest history and evolution of the inner Solar System. As part of an ongoing LASERfunded effort, we are digitizing and georeferencing data from astronaut traverses and spatially associating them to available, co-registered remote sensing data. Here we introduce the products produced so far for Apollo 15, 16, and 17 missions
HST Observations of the Host Galaxy of GRB970508
We report on observations of the field of GRB~970508 made in early August
1998, 454 days after outburst, with the STIS CCD camera onboard the Hubble
Space Telescope. The images, taken in open filter (50CCD) mode, clearly reveal
the presence of a galaxy which was obscured in earlier (June 1997) HST images
by emission from the optical transient (OT). The galaxy is regular in shape:
after correcting for the HST/STIS PSF, it is well-fitted by an exponential disk
with a scale length of 0."046 +/- 0."006 and an ellipticity of 0.70 +/- 0.07.
All observations are marginally consistent with a continuous decline in OT
emission as t^{-1.3} beginning two days after outburst; however, we find no
direct evidence in the image for emission from the OT, and the surface
brightness profile of the galaxy is most regular if we assume that the OT
emission is negligible, suggesting that the OT may have faded more rapidly at
late times than is predicted by the power-law decay. Due to the wide bandwidth
of the STIS clear mode, the estimated magnitude of the galaxy is dependent on
the galaxy spectrum that is assumed. Using colors obtained from late-time
ground-based observations to constrain the spectrum, we find V = 25.4 +/- 0.15,
a few tenths of a magnitude brighter than earlier ground-based estimates that
were obtained by observing the total light of the galaxy and the OT and then
subtracting the estimated OT brightness assuming it fades as a single
power-law. This again suggests that the OT may have faded faster at late time
than the power-law predicts. The position of the OT agrees with that of the
isophotal center of the galaxy to 0."01. This remarkable agreement raises the
possibility that the GRB may have been associated with either an active
galactic nucleus or a nuclear starburst.Comment: Submitted to the Astrophysical Journal (Letters). Thirteen pages,
three encapsulated figures. Abstract slightly abridge
The decay of optical emission from the Gamma-Ray Burst GRB 970228
We present the R_c band light curve of the optical transient (OT) associated
with GRB970228, based on re-evaluation of existing photometry. Data obtained
until April 1997 suggested a slowing down of the decay of the optical
brightness. However, the HST observations in September 1997 show that the light
curve of the point source is well represented by a single power law, with a
``dip'', about a week after the burst occured. The exponent of the power law
decay is = --1.10 0.04. As the point source weakened it also
became redder.Comment: 5 pages, latex, to appear in Gamma-Ray Bursts, 4-th Huntsville
Symposium, eds Meegan, Preece, Koshu
Спеціальний музичний інструмент: В. Власов. Джазові мініатюри для баяна (акордеона). Німе кіно
У методичних матеріалах пропонується короткий опис творчості видатного баяніста, композитора, професора Одеської національної музичної академії імені А. В. Нежданової В. П. Власова. Викладені методичні поради щодо виконання його музичного твору «Німе кіно» на основі запропонованих нот. Методичні рекомендації рекомендовані студентам вищих навчальних закладів напряму “Музичне мистецтво” для курсів «Спеціальний музичний інструмент» та «Методика викладання гри на музичному інструменті», а також аспірантам, учителям, працівникам закладів культури і мистецтв для самостійної роботи
The optical counterpart to gamma-ray burst GRB970228 observed using the Hubble Space Telescope
Although more than 2,000 astronomical gamma-ray bursts (GRBs) have been
detected, and numerous models proposed to explain their occurrence, they have
remained enigmatic owing to the lack of an obvious counterpart at other
wavelengths. The recent ground-based detection of a transient source in the
vicinity of GRB 970228 may therefore have provided a breakthrough. The optical
counterpart appears to be embedded in an extended source which, if a galaxy as
has been suggested, would lend weight to those models that place GRBs at
cosmological distances. Here we report the observations using the Hubble Space
Telescope of the transient counterpart and extended source 26 and 39 days after
the initial gamma-ray outburst. We find that the counterpart has faded since
the initial detection (and continues to fade), but the extended source exhibits
no significant change in brightness between the two dates of observations
reported here. The size and apparent constancy between the two epochs of HST
observations imply that it is extragalactic, but its faintness makes a
definitive statement about its nature difficult. Nevertheless, the decay
profile of the transient source is consistent with a popular impulsive-fireball
model, which assumes a merger between two neutron stars in a distant galaxy.Comment: 11 pages + 2 figures. To appear in Nature (29 May 1997 issue
Observations of GRB 970228 and GRB 970508, and the Neutron-Star Merger Model
We present the discovery observations for the optical counterpart of the
-ray burster GRB 970508 and discuss its light curve in the context of
the fireball model. We analyze the HST data for this object, and conclude that
any underlying galaxy must be fainter than = 25.5. We also present a
detailed analysis of the HST images of GRB 970228 claimed to show a proper
motion of the optical counterpart and conclude that, within the uncertainties,
there is no proper motion. We examine several aspects of the neutron-star
merger model for -ray bursts. In particular, we use this model to
predict the redshift distribution of -ray bursters, and adopting a
recent determination of the cosmic star-formation history, we show that the
predicted distribution of relation is consistent with that
observed for GRBs.Comment: (6 figures). Accepted for publication in Astrophysical Journa
The Decay of Optical Emission from the gamma-Ray Burst GRB970228
The origin of gamma-ray bursts has been one of the great unsolved mysteries in high-energy astrophysics for almost 30 years. The recent discovery of fading sources at X-ray and optical wavelengths coincident with the location of the gamma-ray burst GRB970228 therefore provides an unprecedented opportunity to probe the nature of these high-energy events. The optical counterpart appears to be a transient point source embedded in a region of extended nebulosity, the latter having been tentatively identified as a high-redshift galaxy. This would seem to favour models that place gamma-ray bursts at cosmological distances, although a range of mechanisms for producing the bursts is still allowed. A crucial piece of information for distinguishing between such models is how the brightness of the optical counterpart evolves with time. Here we re-evaluate the existing photometry of the optical counterpart of GRB970228 to construct an optical light curve for the transient event. We find that between 21 hours and six days after the burst, the R-band brightness decreased by a factor of approximately 40, with any subsequent decrease in brightness occurring at a much slower rate. As the point source faded, it also became redder. The initial behaviour of the source appears to be consistent with the 'fireball' model, but the subsequent decrease in the rate of fading may prove harder to explain
Targeting BTK for the treatment of FLT3-ITD mutated acute myeloid leukemia
Approximately 20% of patients with acute myeloid leukaemia (AML) have a mutation in FMS-like-tyrosine-kinase-3 (FLT3). FLT3 is a trans-membrane receptor with a tyrosine kinase domain which, when activated, initiates a cascade of phosphorylated proteins including the SRC family of kinases. Recently our group and others have shown that pharmacologic inhibition and genetic knockdown of Bruton's tyrosine kinase (BTK) blocks AML blast proliferation, leukaemic cell adhesion to bone marrow stromal cells as well as migration of AML blasts. The anti-proliferative effects of BTK inhibition in human AML are mediated via inhibition of downstream NF-κB pro-survival signalling however the upstream drivers of BTK activation in human AML have yet to be fully characterised. Here we place the FLT3-ITD upstream of BTK in AML and show that the BTK inhibitor ibrutinib inhibits the survival and proliferation of FLT3-ITD primary AML blasts and AML cell lines. Furthermore ibrutinib inhibits the activation of downstream kinases including MAPK, AKT and STAT5. In addition we show that BTK RNAi inhibits proliferation of FLT3-ITD AML cells. Finally we report that ibrutinib reverses the cyto-protective role of BMSC on FLT3-ITD AML survival. These results argue for the evaluation of ibrutinib in patients with FLT3-ITD mutated AML
Radio Astronomy
Contains research objectives, summary of research and reports on eleven research projects.National Aeronautics and Space Administration (Grant NGL 22-009-016)National Science Foundation (Grant GP-14854)Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DA 28-043-AMC-02536(E)National Science Foundation (Grant GP-13056)Sloan Fund for Basic Research (M. I. T. Grant 312
Update on the Worsening Particle Radiation Environment Observed by CRaTER and Implications for Future Human Deep‐Space Exploration
Over the last decade, the solar wind has exhibited low densities and magnetic field strengths, representing anomalous states that have never been observed during the space age. As discussed by Schwadron, Blake, et al. (2014, https://doi.org/10.1002/2014SW001084), the cycle 23–24 solar activity led to the longest solar minimum in more than 80 years and continued into the “mini” solar maximum of cycle 24. During this weak activity, we observed galactic cosmic ray fluxes that exceeded theERobserved small solar energetic particle events. Here we provide an update to the Schwadron, Blake, et al. (2014, https://doi.org/10.1002/2014SW001084) observations from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on the Lunar Reconnaissance Orbiter. The Schwadron, Blake, et al. (2014, https://doi.org/10.1002/2014SW001084) study examined the evolution of the interplanetary magnetic field and utilized a previously published study by Goelzer et al. (2013, https://doi.org/10.1002/2013JA019404) projecting out the interplanetary magnetic field strength based on the evolution of sunspots as a proxy for the rate that the Sun releases coronal mass ejections. This led to a projection of dose rates from galactic cosmic rays on the lunar surface, which suggested a ∼20% increase of dose rates from one solar minimum to the next and indicated that the radiation environment in space may be a worsening factor important for consideration in future planning of human space exploration. We compare the predictions of Schwadron, Blake, et al. (2014, https://doi.org/10.1002/2014SW001084) with the actual dose rates observed by CRaTER in the last 4 years. The observed dose rates exceed the predictions by ∼10%, showing that the radiation environment is worsening more rapidly than previously estimated. Much of this increase is attributable to relatively low‐energy ions, which can be effectively shielded. Despite the continued paucity of solar activity, one of the hardest solar events in almost a decade occurred in September 2017 after more than a year of all‐clear periods. These particle radiation conditions present important issues that must be carefully studied and accounted for in the planning and design of future missions (to the Moon, Mars, asteroids, and beyond).Plain Language SummaryWe examine the evolution of fluxes from galactic cosmic rays and recent solar energetic particle events to evaluate the recent evolution of radiation hazards in space and their implications for human and robotic exploration.Key PointsGCR radiation doses are rising faster than predicted previouslySEP radiation events are large despite low solar activityRadiation environment is a significant factor for mission planningPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143683/1/swe20567_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/143683/2/swe20567.pd
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