IGC Antarctic Glaciological Data Field Work 1959-60

"Submitted by RIchard P. Goldthwait to the National Science Foundation, in partial fulfillment of Grant No. NSF-G8992."At head of title: "IGC Antarctic Glaciological Data Field Work 1959-60."The interpretation of 19 snow pits dug by the 1959-60 Victoria Land Traverse gives a mean annual accumulation of 16 cm of water equivalent for the area studied. Deposition is thought to occur in the form of sastrugi instead of in blanket form and this introduces a serious error in the interpretation. Approximate mean annual air temperatures ranged between -38.4°c and -47.4°c. A map of the traverse route shows contoured elevations and sastrugi observations. The highest elevation was 2591 meters. A compilation of accumulation stakes emplaced by this traverse is made available. The Rennick Glacier which empties into Rennick Bay and extends southward for about 300 kilometers was reconnoitered by the traverse party; a sketch map is included. Accumulation stakes were measured on the Ross Ice Shelf, Skelton Glacier, and the Victoria Land Plateau near the coast of the Ross Sea. Annual values ranged from 23.5 cm to 1.7 cm of water equivalent; the higher accumulation is on the Ross Ice Shelf.National Science Foundation Grant No. NSF-G899

Photometric Variability in Earthshine Observations

The identification of an extrasolar planet as Earth-like will depend on the detection of atmospheric signatures or surface non-uniformities. In this paper we present spatially unresolved flux light curves of Earth for the purpose of studying a prototype extrasolar terrestrial planet. Our monitoring of the photometric variability of earthshine revealed changes of up to 23 % per hour in the brightness of Earth's scattered light at around 600 nm, due to the removal of specular reflection from the view of the Moon. This variability is accompanied by reddening of the spectrum, and results from a change in surface properties across the continental boundary between the Indian Ocean and Africa's east coast. Our results based on earthshine monitoring indicate that specular reflection should provide a useful tool in determining the presence of liquid water on extrasolar planets via photometric observations.Comment: To appear in Astrobiology 9(3). 17 pages, 3 figures, 1 tabl

Growing membranes in vitro by continuous phospholipid biosynthesis from free fatty acids

One of the key aspects that defines a cell as a living entity is its ability to self-reproduce. In this process, membrane biogenesis is an essential element. Here, we developed an in vitro phospholipid biosynthesis pathway based on a cascade of eight enzymes, starting from simple fatty acid building blocks and glycerol 3-phosphate. The reconstituted system yields multiple phospholipid species that vary in acyl-chain and polar head group compositions. Due to the high fidelity and versatility, complete conversion of the fatty acid substrates into multiple phospholipid species is achieved simultaneously, leading to membrane expansion as a first step towards a synthetic minimal cell

Orientational effects on the amplitude and phase of polarimeter signals in double resonance atomic magnetometry

Double resonance optically pumped magnetometry can be used to measure static magnetic fields with high sensitivity by detecting a resonant atomic spin response to a small oscillating field perturbation. Determination of the resonant frequency yields a scalar measurement of static field (B_0) magnitude. We present calculations and experimental data showing that the on-resonance polarimeter signal of light transmitted through an atomic vapour in arbitrarily oriented $B_0$ may be modelled by considering the evolution of alignment terms in atomic polarisation. We observe that the amplitude and phase of the magnetometer signal are highly dependent upon B_0 orientation, and present precise measurements of the distribution of these parameters over the full 4 pi solid angle

A test method and deterioration model for joints and cracks in concrete slabs

This paper reports on the development of a laboratory test method to assess the deterioration of concrete cracks and joints under low intensity, high cycle loading, typical of that found in industrial flooring, external hardstandings and rigid pavements. The half-scale prism specimen enables the impact of crack geometry, reinforcement and load magnitude to be assessed in relation to load transfer deterioration, without the need for full scale testing. Each element of the testing procedure has been developed to represent site conditions in respect to crack development, loading and support. A selection of the test results are presented which indicate that joint/crack deterioration consists of four distinct phases, each controlled by a different mechanism of material degradation. This information can be used to enhance understanding of joint/crack behaviour and their failure mechanisms, hence improving design and maintenance procedures

Simplified laboratory assessment of subgrade performance parameters for mechanistic design of pavement foundations

With the increasing agenda for sustainability, the UK is attempting to move away from the empirical design of pavement foundations to develop a performance specification approach to facilitate analytical design. For analytical design the measurement of the subgrade performance parameters of resilient modulus and resistance to permanent deformation are required. These parameters ideally need to be assessed concurrently under loading and environmental conditions similar to those the materials will experience in the field. To date, measurement of these parameters is largely confined to research laboratories using cyclic triaxial testing with advanced on sample strain measurement. This apparatus is considered too complicated for routine commercial use, hence this potentially limits the implementation of laboratory performance evaluation for routine pavement foundation design. A previous program of cyclic triaxial testing on clay subgrades indicated a series of useful correlations between strength and permanent deformation behavior (via a threshold stress), and material resilient modulus at this threshold. This paper reviews the previous work and utilizing these correlations presents data from tests on three different clay materials performed to develop simplified equipment and procedures for the routine measurement of the required design parameters. It is shown that simple pseudo-static tests can measure a subgrade modulus for a simplified performance based design. It re-evaluates the previous data (in the light of the recent work) to show a boundary correlation that may allow a shear strength based parameter to control (in design) the onset of permanent deformation, and details how long-term subgrade water content changes can be accommodated

Identification of genes involved in reproduction and lipid pathway metabolism in wild and domesticated shrimps

The aims of this study were to identify genes involved in reproduction and lipid pathway metabolism in Penaeus monodon and correlate their expression with reproductive performance. Samples of the hepatopancreas and ovaries were obtained from a previous study of the reproductive performance of wild and domesticated P. monodon broodstock. Total mRNA from the domesticated broodstock was used to create two next generation sequencing cDNA libraries enabling the identification of 11 orthologs of key genes in reproductive and nutritional metabolic pathways in P. monodon. These were identified from the library of de novo assembled contigs, including the description of 6 newly identified genes. Quantitative RT-PCR of these genes in the hepatopancreas prior to spawning showed that the domesticated mature females significantly showed higher expression of the Pm Elovl4, Pm COX and Pm SUMO genes. The ovaries of domesticated females had a significantly decreased expression of the Pm Elovl4 genes. In the ovaries of newly spawned females, a significant correlation was observed between hepatosomatic index and the expression of Pm FABP and also between total lipid content and the expression of Pm CYP4. Although not significant, the highest levels of correlation were found between relative fecundity and Pm CRP and Pm CYP4 expression, and between hatching rate and Pm Nvd and Pm RXR expression. This study reports the discovery of genes involved in lipid synthesis, steroid biosynthesis and reproduction in P. monodon. These results indicate that genes encoding enzymes involved in lipid metabolism pathways might be potential biomarkers to assess reproductive performance.&nbsp

Grating chips for quantum technologies

We have laser cooled3x10^6 87Rb atoms to 3uK in a micro-fabricated grating magneto-optical trap (GMOT), enabling future mass-deployment in highly accurate compact quantum sensors. We magnetically trap the atoms, and use Larmor spin precession for magnetic sensing in the vicinity of the atomic sample. Finally, we demonstrate an array of magneto-optical traps with a single laser beam, which will be utilised for future cold atom gradiometry

The role of discharge variability in determining alluvial stratigraphy

We illustrate the potential for using physics-based modeling to link alluvial stratigraphy to large river morphology and dynamics. Model simulations, validated using ground penetrating radar data from the Río Paraná, Argentina, demonstrate a strong relationship between bar-scale set thickness and channel depth, which applies across a wide range of river patterns and bar types. We show that hydrologic regime, indexed by discharge variability and flood duration, exerts a first-order influence on morphodynamics and hence bar set thickness, and that planform morphology alone may be a misleading variable for interpreting deposits. Indeed, our results illustrate that rivers evolving under contrasting hydrologic regimes may have very similar morphology, yet be characterized by marked differences in stratigraphy. This realization represents an important limitation on the application of established theory that links river topography to alluvial deposits, and highlights the need to obtain field evidence of discharge variability when developing paleoenvironmental reconstructions. Model simulations demonstrate the potential for deriving such evidence using metrics of paleocurrent variance

Slow Schroedinger dynamics of gauged vortices

Multivortex dynamics in Manton's Schroedinger--Chern--Simons variant of the Landau-Ginzburg model of thin superconductors is studied within a moduli space approximation. It is shown that the reduced flow on M_N, the N vortex moduli space, is hamiltonian with respect to \omega_{L^2}, the L^2 Kaehler form on \M_N. A purely hamiltonian discussion of the conserved momenta associated with the euclidean symmetry of the model is given, and it is shown that the euclidean action on (M_N,\omega_{L^2}) is not hamiltonian. It is argued that the N=3 flow is integrable in the sense of Liouville. Asymptotic formulae for \omega_{L^2} and the reduced Hamiltonian for large intervortex separation are conjectured. Using these, a qualitative analysis of internal 3-vortex dynamics is given and a spectral stability analysis of certain rotating vortex polygons is performed. Comparison is made with the dynamics of classical fluid point vortices and geostrophic vortices.Comment: 22 pages, 2 figure