Research on quantities and concentrations of extraterrestrial matter through samplings of ocean bottoms Six-month status report, Mar. - Aug. 1965

Quantitiies and concentration of extraterrestrial matter through ocean bottom sampling

Meteorites and the Antarctic ice sheet

The majority of the meteorite finds were located in the Allan Hills site. All the expected goals involving the recovery of rare or previously unknown types of meteorites, and even the recovery of lunar ejecta, were realized. The relationship between these remarkable concentrations of meteorites and the Antarctic ice sheet itself were less well documented. Ice flow vector studies were made and concentration models were proposed. Earlier estimates of the abundances of meteorite types were based on the number of falls in the world collections. The accumulated data and the future collected data will allow more reliable estimates of the source region of most meteorites

Paleomagnetic Determination of Vertical-Axis Block Rotation and Magnetostratigraphy in the Mecca Hills and Coachella Valley, California

Our ongoing work on the paleomagnetism and magnetostratigraphy in the Coachella Valley has provided an improved understanding of the timing and spatial variations of sediment accumulation and deformation during evolution of plate-boundary fault zones. Here, we report updated results from the Palm Spring Formation of the Mecca Hills, and new paleomagnetic data from Pleistocene conglomeratic sandstone in Desert Hot Springs and the Plio-Pleistocene San Timoteo Formation from Live Oak Canyon. From the Mecca Hills, new data were obtained-112 samples from 29 sites. The majority of the paleomagnetic results yielded well-defined components of magnetization, which allowed us to identify seven well defined polarity zones within the Ocotillo and upper Palm Spring Formation. These polarity zones are correlated with the geomagnetic polarity timescale using the Bishop Ash near the top of the section as a tie point. This correlation places the Brunhes-Matuyama boundary at or near the base of the Ocotillo Formation, with the Jaramillo, Olduvai, and Reunion normal polarity sub-chrons occurring in the upper Palm Spring Formation. This indicates that the upper Palm Spring Formation in the Mecca Hills was deposited between ca. 2.3 and 0.9 Ma. Tilt corrected mean directions from the Mecca Hills section are D = 343, I = 53, α95 =11.3 N = 5 for normal sites, and D = 175, I = -50, α95 = 4.9 N = 24 for reverse sites. Normal and reverse sites combined as a single mode have a mean direction of D = 353, I = 51 α95 = 4.4. These mean directions indicated modest (7 degrees) of CCW rotation with no significant variation in amount or sense of rotation observed within the section. Specimens from 19 sites (53 samples) of the Pleistocene conglomeritic sandstone from Desert Hot Springs have very well-defined paleomagnetic components. Six of the sites have normal polarity, 13 sites have reverse polarity. Sites with normal polarity have a mean direction of D = 358, I = 45, α95 = 13 and reverse sites have a mean of D = 182, I = -50, α95 = 6.6.The combined mean direction (in tilt-corrected coordinates) is D = 0.7, I = 49, α95 = 5.6, supporting 3.1° ± 2.3° of CW rotation at this location since ~1 to 1.5 Ma. Specimens from 8 sites (35 samples) of the upper-most San Timoteo Formation from Live Oak Canyon also have well-defined paleomagnetic components for 6 sites. All of the results have normal polarity, and one site has a direction that is \u3e40 degree from the other sites. The mean of the remaining 5 sites is D = 11, I = 49, k=51, a95=11. The new and updated paleomagnetic results from the Coachella Valley collectively indicate that this area has experienced modest (in most cases less than 10 degrees) CW or CCW rotation during the past 1-2 Ma. The lack of variation in amount or sense of rotation as a function of age suggest that rotation has been relatively recent (during the past ~ 1 Ma)

Proceedings of a Workshop on Antarctic Meteorite Stranding Surfaces

The discovery of large numbers of meteorites on the Antarctic Ice Sheet is one of the most exciting developments in polar science in recent years. The meteorites are found on areas of ice called stranding surfaces. Because of the sudden availability of hundreds, and then thousands, of new meteorite specimens at these sites, the significance of the discovery of meteorite stranding surfaces in Antarctica had an immediate and profound impact on planetary science, but there is also in this discovery an enormous, largely unrealized potential to glaciology for records of climatic and ice sheet changes. The glaciological interest derives from the antiquity of the ice in meteorite stranding surfaces. This exposed ice covers a range of ages, probably between zero and more than 500,000 years. The Workshop on Antarctic Meteorite Stranding Surfaces was convened to explore this potential and to devise a course of action that could be recommended to granting agencies. The workshop recognized three prime functions of meteorite stranding surfaces. They provide: (1) A proxy record of climatic change (i.e., a long record of climatic change is probably preserved in the exposed ice stratigraphy); (2) A proxy record of ice volume change; and (3) A source of unique nonterrestrial material

The Upregulation of α2δ-1 Subunit Modulates Activity-Dependent Ca2+ Signals in Sensory Neurons.

As auxiliary subunits of voltage-gated Ca(2+) channels, the α2δ proteins modulate membrane trafficking of the channels and their localization to specific presynaptic sites. Following nerve injury, upregulation of the α2δ-1 subunit in sensory dorsal root ganglion neurons contributes to the generation of chronic pain states; however, very little is known about the underlying molecular mechanisms. Here we show that the increased expression of α2δ-1 in rat sensory neurons leads to prolonged Ca(2+) responses evoked by membrane depolarization. This mechanism is coupled to CaV2.2 channel-mediated responses, as it is blocked by a ω-conotoxin GVIA application. Once initiated, the prolonged Ca(2+) transients are not dependent on extracellular Ca(2+) and do not require Ca(2+) release from the endoplasmic reticulum. The selective inhibition of mitochondrial Ca(2+) uptake demonstrates that α2δ-1-mediated prolonged Ca(2+) signals are buffered by mitochondria, preferentially activated by Ca(2+) influx through CaV2.2 channels. Thus, by controlling channel abundance at the plasma membrane, the α2δ-1 subunit has a major impact on the organization of depolarization-induced intracellular Ca(2+) signaling in dorsal root ganglion neurons

Nanotechnology in the Regeneration of Complex Tissues.

This is the final published version. It first appeared at http://www.la-press.com/nanotechnology-in-the-regeneration-of-complex-tissues-article-a4503.Modern medicine faces a growing crisis as demand for organ transplantations continues to far outstrip supply. By stimulating the body's own repair mechanisms, regenerative medicine aims to reduce demand for organs, while the closely related field of tissue engineering promises to deliver "off-the-self" organs grown from patients' own stem cells to improve supply. To deliver on these promises, we must have reliable means of generating complex tissues. Thus far, the majority of successful tissue engineering approaches have relied on macroporous scaffolds to provide cells with both mechanical support and differentiative cues. In order to engineer complex tissues, greater attention must be paid to nanoscale cues present in a cell's microenvironment. As the extracellular matrix is capable of driving complexity during development, it must be understood and reproduced in order to recapitulate complexity in engineered tissues. This review will summarize current progress in engineering complex tissue through the integration of nanocomposites and biomimetic scaffolds.JWC was previously funded by a Scholarship from the University of Glasgow and is now in receipt of a Cancer Research UK Scholarship

Generalized Thermalization in an Integrable Lattice System

After a quench, observables in an integrable system may not relax to the standard thermal values, but can relax to the ones predicted by the generalized Gibbs ensemble (GGE) [M. Rigol et al., Phys. Rev. Lett. 98, 050405 (2007)]. The GGE has been shown to accurately describe observables in various one-dimensional integrable systems, but the origin of its success is not fully understood. Here we introduce a microcanonical version of the GGE and provide a justification of the GGE based on a generalized interpretation of the eigenstate thermalization hypothesis, which was previously introduced to explain thermalization of nonintegrable systems. We study relaxation after a quench of one-dimensional hard-core bosons in an optical lattice. Exact numerical calculations for up to 10 particles on 50 lattice sites (~10^10 eigenstates) validate our approach.Comment: 8 pages, 9 figures, as publishe

Solar wind radiation damage effects in lunar material

The research on solar wind radiation damage and other effects in lunar samples which was conducted to understand the optical properties of lunar materials is reported. Papers presented include: solar radiation effects in lunar samples, albedo of the moon, radiation effects in lunar crystalline rocks, valence states of 3rd transition elements in Apollo 11 and 12 rocks, and trace ferric iron in lunar and meteoritic titanaugites