Multiple M0-brane equations in eleven dimensional pp-wave superspace and BMN matrix model

We obtain the Matrix model equations in the background of the maximally supersymmetric pp-wave solution of the 11D supergravity and discuss its relation with the Berenstein-Maldacena-Nastase (BMN) model.Comment: 14 pages, revtex4, no figure

STRINGY EVIDENCE FOR D=11 STRUCTURE IN STRONGLY COUPLED TYPE II-A SUPERSTRING

Witten proposed that the low energy physics of strongly coupled D=10 type-IIA superstring may be described by D=11 supergravity. To explore the stringy aspects of the underlying theory we examine the stringy massive states. We propose a systematic formula for identifying non-perturbative states in D=10 type-IIA superstring theory, such that, together with the elementary excited string states, they form D=11 supersymmetric multiplets multiplets in SO(10) representations. This provides hints for the construction of a weakly coupled D=11 theory that is dual to the strongly coupled D=10 type IIA superstring.Comment: LaTeX, revtex, 2-column, 10 pages

The use of Pb isotope ratios determined by magnetic sector ICP-MS for tracing Pb pollution in marine sediments near Casey Station, East Antarctica

Magnetic sector inductively coupled plasma mass spectrometry (ICP-SMS) was used to measure lead concentrations and isotope ratios in marine sediments and other samples collected from near the Australian Antarctic Station Casey. Precisions obtained from the repetitive analysis of a standard Broken Hill Pb sample at a concentration of approximately 40 ng g-1 in solution were less than plus or minus 0.2% for ratios involving 204Pb, and less than plus or minus 0.1% for those referenced to 206Pb or 207Pb (n ~ 12 replicates over 2 days, values as 1s). Ratios were accurate to within less than plus or minus 0.1% for the analysis of this standard sample. Comparative measurements between ICP-SMS and TIMS had typical differences in values of less than 0.4% for contaminated samples, irrespective of ratio. For marine sediment samples with Pb concentrations in the sample digest of greater than 10 ng g-1, instrumental capability was characterised by isotopic precisions ranging from 0.1-0.5% (1s) for ratios involving 204Pb, and less than 0.25% (1s) for ratios with 206Pb or 207Pb as the basis (typically found from triplicate analyses). For sediments of low Pb concentration (less than 10 ng g-1 in the sample digest), isotope ratios to 204Pb were found to be limited by instrument counting statistics when using standard ICP-SMS. To help overcome this problem, Pb isotope ratios for these samples were measured with a capacitive decoupling Pt guard electrode employed, offering considerable signal enhancement (5-10x). These natural background sediments were found to display typical Pb isotope ratios of 40.5, 15.5, 18.6 and 1.19 for 208Pb/204Pb, 207Pb/204Pb, 206Pb/204Pb and 206Pb/207Pb. For comparison, the most contaminated samples had Pb isotope ratios of approximately 36.2, 15.4, 16.4 and 1.06 for 208Pb/204Pb, 207Pb/204Pb, 206Pb/204Pb and 206Pb/207Pb, respectively. Evidence of simple two component mixing between anthropogenic and natural geogenic Pb was found near Casey Station. Runoff from the Thala Valley tip site, adjacent to the bay, was identified as a clear source of Pb pollution, with impacted sediments displaying an isotopic signature approaching that of abandoned lead batteries collected from the tip. These batteries possessed Pb isotope ratios identical to Australian Broken Hill lead. In this study, the use of Pb isotope data has proved to be a sensitive method of assessing contamination levels in the Antarctic marine environment adjacent to a waste disposal site. Lead isotope ratios have proved superior to simple elemental concentration determinations when distinguishing between impacted and non-impacted samples. ICP-SMS has been shown to offer relatively fast, accurate and cost effective Pb isotope ratios, with precisions suitable for many environmental applications

Hamilton-Jacobi method for Domain Walls and Cosmologies

We use Hamiltonian methods to study curved domain walls and cosmologies. This leads naturally to first order equations for all domain walls and cosmologies foliated by slices of maximal symmetry. For Minkowski and AdS-sliced domain walls (flat and closed FLRW cosmologies) we recover a recent result concerning their (pseudo)supersymmetry. We show how domain-wall stability is consistent with the instability of adS vacua that violate the Breitenlohner-Freedman bound. We also explore the relationship to Hamilton-Jacobi theory and compute the wave-function of a 3-dimensional closed universe evolving towards de Sitter spacetime.Comment: 18 pages; v2: typos corrected, one ref added, version to appear in PR

Expandable Purge Chambers Would Protect Cryogenic Fittings

Expandable ice-prevention and cleanliness-preservation (EIP-CP) chambers have been proposed to prevent the accumulation of ice or airborne particles on quick-disconnect (QD) fittings, or on ducts or tubes that contain cryogenic fluids. In the original application for which the EIP-CP chambers were conceived, there is a requirement to be able to disconnect and reconnect the QD fittings in rapid succession. If ice were to form on the fittings by condensation and freezing of airborne water vapor on the cold fitting surfaces, the ice could interfere with proper mating of the fittings, making it necessary to wait an unacceptably long time for the ice to thaw before attempting reconnection. By keeping water vapor away from the cold fitting surfaces, the EIP-CP chambers would prevent accumulation of ice, preserving the ability to reconnect as soon as required. Basically, the role of an EIP-CP chamber would be to serve as an enclosure for a flow of dry nitrogen gas that would keep ambient air away from QD cryogenic fittings. An EIP-CP chamber would be an inflatable device made of a fabriclike material. The chamber would be attached to an umbilical plate holding a cryogenic QD fitting

Multiple M0-brane system in an arbitrary eleven dimensional supergravity background

The equations of motion of multiple M0{brane (multiple M-wave or mM0) system in an arbitrary D = 11 supergravity superspace, which generalize the Matrix model equations for the case of inter- action with a generic 11D supergravity background, are obtained in the frame of superembedding approach. We also derive the BPS equations for supersymmetric bosonic solutions of these mM0 equations and show that the set of 1/2 BPS solutions contain a fuzzy sphere modeling M2 brane as well as that the Nahm equation appears as a particular case of the 1/4 BPS equations.Comment: RevTeX4, 20 pages, no figures. V2: misprints corrected, minor changes, published in Phys. Rev. D82, 105030 (2010)). V3. Dec. 2011 : misprints in coeffs of Eqs.(5.10) correcte

Supersymmetric Two-Time Physics

We construct an Sp(2,R) gauge invariant particle action which possesses manifest space-time SO(d,2) symmetry, global supersymmetry and kappa supersymmetry. The global and local supersymmetries are non-abelian generalizations of Poincare type supersymmetries and are consistent with the presence of two timelike dimensions. In particular, this action provides a unified and explicit superparticle representation of the superconformal groups OSp(N/4), SU(2,2/N) and OSp(8*/N) which underlie various AdS/CFT dualities in M/string theory. By making diverse Sp(2,R) gauge choices our action reduces to diverse one-time physics systems, one of which is the ordinary (one-time) massless superparticle with superconformal symmetry that we discuss explicitly. We show how to generalize our approach to the case of superalgebras, such as OSp(1/32), which do not have direct space-time interpretations in terms of only zero branes, but may be realizable in the presence of p-branes.Comment: Latex, 18 page

Symplectic connections, Noncommutative Yang Mills theory and Supermembranes

In built noncommutativity of supermembranes with central charges in eleven dimensions is disclosed. This result is used to construct an action for a noncommutative supermembrane where interesting topological terms appear. In order to do so, we first set up a global formulation for noncommutative Yang Mills theory over general symplectic manifolds. We make the above constructions following a pure geometrical procedure using the concept of connections over Weyl algebra bundles on symplectic manifolds. The relation between noncommutative and ordinary supermembrane actions is discussed.Comment: 18 page

Influence of correlated visual cues on auditory signal detection

Influence of correlated visual cues on auditory signal detectio

Lunar Regolith Simulant Feed System for a Hydrogen Reduction Reactor System

One of the goals of In-Situ Resource Utilization (ISRU) on the moon is to produce oxygen from the lunar regolith which is present in the form of Ilmenite (FeTi03) and other compounds. A reliable and attainable method of extracting some of the oxygen from the lunar regolith is to use the hydrogen reduction process in a hot reactor to create water vapor which is then condensed and electrolyzed to obtain oxygen for use as a consumable. One challenge for a production system is to reliably acquire the regolith with an excavator hauler mobility platform and then introduce it into the reactor inlet tube which is raised from the surface and above the reactor itself. After the reaction, the hot regolith (-1000 C) must be expelled from the reactor for disposal by the excavator hauler mobility system. In addition, the reactor regolith inlet and outlet tubes must be sealed by valves during the reaction in order to allow collection of the water vapor by the chemical processing sub-system. These valves must be able to handle abrasive regolith passing through them as well as the heat conduction from the hot reactor. In 2008, NASA has designed and field tested a hydrogen reduction system called ROxygen in order to demonstrate the feasibility of extracting oxygen from lunar regolith. The field test was performed with volcanic ash known as Tephra on Mauna Kea volcano on the Big Island of Hawai'i. The tephra has similar properties to lunar regolith, so that it is regarded as a good simulant for the hydrogen reduction process. This paper will discuss the design, fabrication, operation, test results and lessons learned with the ROxygen regolith feed system as tested on Mauna Kea in November 2008