Polarization modes for strong-field gravitational waves

Strong-field gravitational plane waves are often represented in either the Rosen or Brinkmann forms. These forms are related by a coordinate transformation, so they should describe essentially the same physics, but the two forms treat polarization states quite differently. Both deal well with linear polarizations, but there is a qualitative difference in the way they deal with circular, elliptic, and more general polarization states. In this article we will describe a general algorithm for constructing arbitrary polarization states in the Rosen form.Comment: 4 pages. Prepared for the proceedings of ERE2010 (Granada, Spain

General polarization modes for the Rosen gravitational wave

Strong-field gravitational plane waves are often represented in either the Rosen or Brinkmann forms. While these two metric ansatze are related by a coordinate transformation, so that they should describe essentially the same physics, they rather puzzlingly seem to treat polarization states quite differently. Both ansatze deal equally well with + and X linear polarizations, but there is a qualitative difference in they way they deal with circular, elliptic, and more general polarization states. In this article we will develop a general formalism for dealing with arbitrary polarization states in the Rosen form of the gravitational wave metric, representing an arbitrary polarization by a trajectory in a suitably defined two dimensional hyperbolic plane.Comment: V1: 12 pages, no figures. V2: still 12 pages, reformatted. Minor technical edits, discussion of Riemann tensor added, two references added, no significant physics changes. This version accepted for publication in Classical and Quantum Gravit

Transillumination imaging through scattering media by use of photorefractive polymers

We demonstrate the use of a near-infrared-sensitive photorefractive polymer with high efficiency for imaging through scattering media, using an all-optical holographic time gate. Imaging through nine scattering mean free paths is performed at 800 nm with a mode-locked continuous-wave Ti:sapphire laser

Heat flow and geothermal potential of Kansas

Temperature, thermal-conductivity measurements, and heat-flow values are presented for four holes in Kansas originally drilled for cooperative water-resources investigations by the Kansas Geological Survey and the U.S. Geological Survey. These holes cut most of the sedimentary section and were cased and allowed to reach temperature equilibrium. Several types of geophysical logs were run for these holes. Temperature data from an additional five wells also are presented. Temperature gradients in the sedimentary section vary over a large range (over 4:1), and significantly different temperatures occur at the same depth in different portions of the state. Temperatures as high as 34°C (93°F) occur at a depth of 500 m (1,650 ft) in the south-central portion of the state but are 28°C (82°F) or lower at that depth in other parts of the state. In addition to cuttings measurements, thermal conductivities were estimated from geophysical well-log parameters; useful results suggest more use of the technique in the future. With these results, geophysical well logs can be used to predict temperatures as a function of depth in areas for which no temperatures are available if heat flow is assumed. The extreme variation in gradients observed in the holes occurs because of the large contrast in thermal-conductivity values. Shale thermal-conductivity values appear to have been overestimated in the past; Paleozoic shales in Kansas have thermal-conductivity values of approximately 1.18 ± 0.03 Wm-1K-1. Conversely, evaporite and dolomite units have thermal conductivities of over 4 Wm-1K-1. In spite of the large variations of gradient, the heat-flow values throughout the holes do not vary more than 10%, and any water-flow effects which might be present from the lateral motion on any of the aquifers are less than 10%. The best estimates for heat flow in the four holes come from carbonate units below the base of the Pennsylvanian and range in value from 48 mWm-2 to 62 mWm-2. Two of the holes were drilled to the basement, and correlation of the heat flow with basement radioactivity suggests that the heat-flow/heat-production line postulated for the midcontinent by Roy, Blackwell, and Birch (1968) applies to these data. Because of the low thermal conductivity of the shales, the radiogenic-pluton concept should apply to the midcontinent. Thus, if very radioactive plutons can be identified, much higher temperatures may occur in the sedimentary section than have been thought possible in the past. However, the past overestimation of the shale-conductivity values suggests that some previous high heat-flow values in the midcontinent probably are not correct, and the high gradients are due instead to normal heat flow and very low thermal-conductivity values. In spite of the presence of-low thermal-conductivity values in the midcontinent region, significant use could be made of geothermal energy in Kansas for space heating, thermal assistance, and heat-pump applications because the temperatures in the sedimentary section in much of Kansas are in excess of 40°C (104°F)

Heat flow and geothermal potential of Kansas

Temperature, thermal-conductivity measurements, and heat-flow values are presented for four holes in Kansas originally drilled for cooperative water-resources investigations by the Kansas Geological Survey and the U.S. Geological Survey. These holes cut most of the sedimentary section and were cased and allowed to reach temperature equilibrium. Several types of geophysical logs were run for these holes. Temperature data from an additional five wells also are presented. Temperature gradients in the sedimentary section vary over a large range (over 4:1), and significantly different temperatures occur at the same depth in different portions of the state. Temperatures as high as 34°C (93°F) occur at a depth of 500 m (1,650 ft) in the south-central portion of the state but are 28°C (82°F) or lower at that depth in other parts of the state. In addition to cuttings measurements, thermal conductivities were estimated from geophysical well-log parameters; useful results suggest more use of the technique in the future. With these results, geophysical well logs can be used to predict temperatures as a function of depth in areas for which no temperatures are available if heat flow is assumed. The extreme variation in gradients observed in the holes occurs because of the large contrast in thermal-conductivity values. Shale thermal-conductivity values appear to have been overestimated in the past; Paleozoic shales in Kansas have thermal-conductivity values of approximately 1.18 ± 0.03 Wm-1K-1. Conversely, evaporite and dolomite units have thermal conductivities of over 4 Wm-1K-1. In spite of the large variations of gradient, the heat-flow values throughout the holes do not vary more than 10%, and any water-flow effects which might be present from the lateral motion on any of the aquifers are less than 10%. The best estimates for heat flow in the four holes come from carbonate units below the base of the Pennsylvanian and range in value from 48 mWm-2 to 62 mWm-2. Two of the holes were drilled to the basement, and correlation of the heat flow with basement radioactivity suggests that the heat-flow/heat-production line postulated for the midcontinent by Roy, Blackwell, and Birch (1968) applies to these data. Because of the low thermal conductivity of the shales, the radiogenic-pluton concept should apply to the midcontinent. Thus, if very radioactive plutons can be identified, much higher temperatures may occur in the sedimentary section than have been thought possible in the past. However, the past overestimation of the shale-conductivity values suggests that some previous high heat-flow values in the midcontinent probably are not correct, and the high gradients are due instead to normal heat flow and very low thermal-conductivity values. In spite of the presence of-low thermal-conductivity values in the midcontinent region, significant use could be made of geothermal energy in Kansas for space heating, thermal assistance, and heat-pump applications because the temperatures in the sedimentary section in much of Kansas are in excess of 40°C (104°F)

Photoionization and Photoelectric Loading of Barium Ion Traps

Simple and effective techniques for loading barium ions into linear Paul traps are demonstrated. Two-step photoionization of neutral barium is achieved using a weak intercombination line (6s2 1S0 6s6p 3P1, 791 nm) followed by excitation above the ionization threshold using a nitrogen gas laser (337 nm). Isotopic selectivity is achieved by using a near Doppler-free geometry for excitation of the triplet 6s6p 3P1 state. Additionally, we report a particularly simple and efficient trap loading technique that employs an in-expensive UV epoxy curing lamp to generate photoelectrons.Comment: 5 pages, Accepted to PRA 3/20/2007 -fixed typo -clarified figure 3 caption -added reference [15

Pigment production and isotopic fractionations in continuous culture: okenone producing purple sulfur bacteria Part II

Okenone is a carotenoid pigment unique to certain members of Chromatiaceae, the dominant family of purple sulfur bacteria (PSB) found in euxinic photic zones. Diagenetic alteration of okenone produces okenane, the only recognized molecular fossil unique to PSB. The in vivo concentrations of okenone and bacteriochlorophyll a (Bchl a) on a per cell basis were monitored and quantified as a function of light intensity in continuous cultures of the purple sulfur bacterium Marichromatium purpuratum (Mpurp1591). We show that okenone-producing PSB have constant bacteriochlorophyll to carotenoid ratios in light-harvesting antenna complexes. The in vivo concentrations of Bchl a, 0.151 ± 0.012 fmol cell^(−1), and okenone, 0.103 ± 0.012 fmol cell^(−1), were not dependent on average light intensity (10–225 Lux) at both steady and non-steady states. This observation revealed that in autotrophic continuous cultures of Mpurp1591, there was a constant ratio for okenone to Bchl a of 1:1.5. Okenone was therefore constitutively produced in planktonic cultures of PSB, regardless of light intensity. This confirms the legitimacy of okenone as a signature for autotrophic planktonic PSB and by extrapolation water column euxinia. We measured the δ^(13)C, δ^(15)N, and δ^(34)S bulk biomass values from cells collected daily and determined the isotopic fractionations of Mpurp1591. There was no statistical relationship in the bulk isotope measurements or stable isotope fractionations to light intensity or cell density under steady and non-steady-state conditions. The carbon isotope fractionation between okenone and Bchl a with respect to overall bulk biomass (^(13)ε_pigment – biomass) was 2.2 ± 0.4‰ and −4.1 ± 0.9‰, respectively. The carbon isotopic fractionation (^(13)ε_pigment-CO_2) for the production of pigments in PSB is more variable than previously thought with our reported values for okenone at −15.5 ± 1.2‰ and −21.8 ± 1.7‰ for Bchl a

The impact of population-based faecal occult blood test screening on colorectal cancer mortality:a matched cohort study

BACKGROUND: Randomised trials show reduced colorectal cancer (CRC) mortality with faecal occult blood testing (FOBT). This outcome is now examined in a routine, population-based, screening programme. METHODS: Three biennial rounds of the UK CRC screening pilot were completed in Scotland (2000–2007) before the roll out of a national programme. All residents (50–69 years) in the three pilot Health Boards were invited for screening. They received a FOBT test by post to complete at home and return for analysis. Positive tests were followed up with colonoscopy. Controls, selected from non-pilot Health Boards, were matched by age, gender, and deprivation and assigned the invitation date of matched invitee. Follow-up was from invitation date to 31 December 2009 or date of death if earlier. RESULTS: There were 379 655 people in each group (median age 55.6 years, 51.6% male). Participation was 60.6%. There were 961 (0.25%) CRC deaths in invitees, 1056 (0.28%) in controls, rate ratio (RR) 0.90 (95% confidence interval (CI) 0.83–0.99) overall and 0.73 (95% CI 0.65–0.82) for participants. Non-participants had increased CRC mortality compared with controls, RR 1.21 (95% CI 1.06–1.38). CONCLUSION: There was a 10% relative reduction in CRC mortality in a routine screening programme, rising to 27% in participants