The EVLA: Prospects for HI

To continue the unparalleled success of the Very Large Array (VLA) for radio astronomy, the facility is currently being converted to become the 'Expanded VLA' (EVLA). The EVLA will radically improve the VLA in order to cover the full 0.93-50 GHz radio wavelength range without gaps, provide up to an order of magnitude better sensitivity, and to allow observations at much larger bandwidths and spectral resolution as currently possible. For observations of the 21 cm line of atomic neutral hydrogen (HI), the EVLA offers thousands of km/s velocity coverage at sub-km/s resolution for targeted observations as well as an improved spectral baseline stability. In addition, every L-band (21 cm) continuum or targeted HI observation can be set-up to simultaneously observe a full z=0-0.53 HI redshift survey at a velocity resolution of a few km/s. In turn, every HI observation will also yield deep radio continuum images of the field. These synergies will deliver a wealth of data which opens up a wide 'discovery space' to study the details of galaxy evolution and cosmology.Comment: to appear in the proceedings to the conference: "The Evolution of Galaxies through the Neutral Hydrogen Window", Arecibo, PR, US

Solving optimization problems with local light shift encoding on Rydberg quantum annealers

We provide a non-unit disk framework to solve combinatorial optimization problems such as Maximum Cut (Max-Cut) and Maximum Independent Set (MIS) on a Rydberg quantum annealer. Our setup consists of a many-body interacting Rydberg system where locally controllable light shifts are applied to individual qubits in order to map the graph problem onto the Ising spin model. Exploiting the flexibility that optical tweezers offer in terms of spatial arrangement, our numerical simulations implement the local-detuning protocol while globally driving the Rydberg annealer to the desired many-body ground state, which is also the solution to the optimization problem. Using optimal control methods, these solutions are obtained for prototype graphs with varying sizes at time scales well within the system lifetime and with approximation ratios close to one. The non-blockade approach facilitates the encoding of graph problems with specific topologies that can be realized in two-dimensional Rydberg configurations and is applicable to both unweighted as well as weighted graphs. A comparative analysis with fast simulated annealing is provided which highlights the advantages of our scheme in terms of system size, hardness of the graph, and the number of iterations required to converge to the solution.Comment: 18 pages, 6 figures, 1 tabl

Fiber Amplifier Report for NEPP 2008

Ongoing qualification activities of LiNbO3 modulators. Passive (unpumped) radiation testing of Er-, Yb-, and Er/Yb-doped fibers: a) Yb-doped fibers exhibit higher radiation resistance than Er-doped fibers; b) Er/Yb co-doped fibers exhibit largest radiation resistance. Active (pumped) radiation testing of Yb-doped fibers conducted at NASA GSFC: a) Typical decay behavior observed; b) No comparison could be made to other fibers due to problems with test setup. Development of new high power fiber terminations

Evaluation of Small Form Factor Fiber Optic Interconnects for the NASA Electronics Parts and Packaging Program (NEPP)

The Diamond AVIM optical fiber connector has been used for over a decade in flight environments. AVIM which stands for Aviation Intermediate Maintenance is always referenced as a fiber optic connector type from the DIN (Deutsches Institut fur Normung) family of optical fiber connectors. The newly available Mini AVIM and DMI (Definition Multimedia Interface) connectors also by Diamond provide similar features as the high performance AVIM with the added benefits of being small form factor for board mount and internal box use where long connectors and strain relief can not be accommodated. Transceiver, fiber laser technology and receiver optic technology based on small sized constraints will benefit the most by the reduction in connector form factor. It is for this reason that the Mini AVIM is being evaluated for multimode and single mode optical fiber use in both fiber based and cable based packaging configurations. In a fiber based termination, there are no cable materials to bond to the connector. The only bonding that is conducted is the mounting of the fiber with epoxy to the connector ferrules (which are called DMI ferrules). In a cable configuration, the compatibility of the connector subcomponents along with the upjacketing materials of the cable around the fiber needs to be considered carefully for termination fabrication. Cabled terminations will show greater insertion loss and high probability of failures during thermal cycling testing. This is due to the stressing of the combination of materials that each have different Coefficients of Thermal Expansion (CTE's) and that are bonded together to the connector subcomponents. As the materials flex during thermal excursions, forces are applied to the termination and can make the system fail if the grouping of materials (per their CTE's) are not compatible and this includes cable materials, epoxies, ferrule and connector body components. For this evaluation, multimode 100 micron core step index fiber was used for the fiber terminated condition, and single mode SMF-28 upjacketed with W.L. Gore Flexlite was used for the cabled configuration. For background purposes, a comparison is presented here for information purposes between the high performance AVIM connector features and the Mini AVIM small form factor connectors. Basic connector features are described here

Fiber Optic Cable Thermal Preparation to Ensure Stable Operation

Fiber optic cables are widely used in modern systems that must provide stable operation during exposure to changing environmental conditions. For example, a fiber optic cable on a satellite may have to reliably function over a temperature range of -50 C up to 125 C. While the system requirements for a particular application will dictate the exact method by which the fibers should be prepared, this work will examine multiple ruggedized fibers prepared in different fashions and subjected to thermal qualification testing. The data show that if properly conditioned the fiber cables can provide stable operation, but if done incorrectly, they will have large fluctuations in transmission

Photocatalytic activity of exfoliated graphite-TiO2_2 nanocomposites

We investigate the photocatalytic performance of composites prepared in a one-step process by liquid-phase exfoliation of graphite in the presence of TiO2 nanoparticles (NPs) at atmospheric pressure and in water, without heating or adding any surfactant, and starting from low-cost commercial reagents. These show enhanced photocatalytic activity, degrading up to 40% more pollutants with respect to the starting TiO2-NPs, in the case of a model dye target, and up to 70% more pollutants in the case of nitrogen oxides. In order to understand the photo-physical mechanisms underlying this enhancement, we investigate the photo-generation of reactive species (trapped holes and electrons) by ultrafast transient absorption spectroscopy. We observe an electron transfer process from TiO2 to the graphite flakes within the first picoseconds of the relaxation dynamics, which causes the decrease of the charge recombination rate, and increases the efficiency of the reactive species photo-production.We acknowledge funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 785219 (GrapheneCore2), EU Neurofibres, ERC Minegrace and Hetero2D, EPSRC Grants EP/509K01711X/1, EP/K017144/1, EP/N010345/1, EP/M507799/5101, and EP/L016087/1

Pregnane X receptor regulates drug metabolism and transport in the vasculature and protects from oxidative stress

Aims Circulating endogenous, dietary and foreign chemicals can contribute to vascular dysfunction. The mechanism by which the vasculature protects itself from these chemicals is unknown. This study investigates whether the pregnane X receptor (PXR), the major transcriptional regulator of hepatic drug metabolism and transport that responds to such xenobiotics, mediates vascular protection by co-ordinating a defence gene program in the vasculature.Methods and Results PXR was detected in primary human and rat aortic endothelial and smooth muscle cells and blood vessels including human and rat aorta. Metabolic PXR target genes cytochrome P450 3A, 2B, 2C and glutathione-S-transferase mRNA and activity were induced by PXR ligands in rodent and human vascular cells and absent in the aortas from PXR null mice stimulated in vivo or in rat aortic smooth muscle cells expressing dominant negative PXR. Activation of aortic PXR by classical agonists had several protective effects; increased xenobiotic metabolism demonstrated by bio-activation of the pro-drug clopidogrel, which reduced adenosine diphosphate-induced platelet aggregation; increased expression of multidrug resistance protein 1, mediating chemical efflux from the vasculature; and protection from reactive oxygen species-mediated cell death.Conclusions PXR co-ordinately up-regulates drug metabolism, transport and anti-oxidant genes to protect the vasculature from endogenous and exogenous insults, thus representing a novel gatekeeper for vascular defence

Atlantic Ocean Observing Networks: Cost and feasibility study

Results of a cost and feasibility study of the present and planned integrated Atlantic Ocean Observing System, including assessing the readiness and feasibility of implementation of different observing technologie

CMS physics technical design report : Addendum on high density QCD with heavy ions

Peer reviewe

Solving optimization problems with local light-shift encoding on Rydberg quantum annealers

We provide a non-unit-disk framework to solve combinatorial optimization problems such as maximum cut and maximum independent set on a Rydberg quantum annealer. Our setup consists of a many-body interacting Rydberg system where locally controllable light shifts are applied to individual qubits in order to map the graph problem onto the Ising spin model. Exploiting the flexibility that optical tweezers offer in terms of spatial arrangement, our numerical simulations implement the local-detuning protocol while globally driving the Rydberg annealer to the desired many-body ground state, which is also the solution to the optimization problem. Using optimal control methods, these solutions are obtained for prototype graphs with varying sizes at timescales well within the system lifetime and with approximation ratios close to one. The nonblockade approach facilitates the encoding of graph problems with specific topologies that can be realized in two-dimensional Rydberg configurations and is applicable to both unweighted as well as weighted graphs. A comparative analysis with fast simulated annealing is provided which highlights the advantages of our scheme in terms of system size, hardness of the graph, and the number of iterations required to converge to the solution