Position paper on the potential of inadvertent weather modification of the Florida peninsula resulting from the stabilized ground cloud

Based on the climatology of the Florida Peninsula, we assessed the risk for weather modification. Certain weather situations warrant launch rescheduling because of the risk of possible impact on hurricanes, hail formation and lightning activity, strong wind developments, and intensification of high rainfall rates. The cumulative effects of 40 launches per year on weather modification were found to be insignificant

Position paper on the potential of inadvertent weather modification of the Florida Peninsula resulting from neutralization of space shuttle solid rocket booster exhaust clouds

A concept of injecting compounds into the exhaust cloud was proposed to neutralize the acidic nature of the low-level stabilized ground cloud (SGC) was studied. The potential Inadvertent Weather Modification caused by exhaust cloud characteristics from three hours to seven days after launch was studied. Possible effects of the neutralized SGC in warm and cloud precipitation processes were discussed. Based on a detailed climatology of the Florida Peninsula, the risk for weather modification under a variety of weather situations was assessed

Spin anisotropy of the resonance in superconducting FeSe0.5Te0.5

We have used polarized-neutron inelastic scattering to resolve the spin fluctuations in superconducting FeSe0.5Te0.5 into components parallel and perpendicular to the layers. A spin resonance at an energy of 6.5 meV is observed to develop below T_c in both fluctuation components. The resonance peak is anisotropic, with the in-plane component slightly larger than the out-of-plane component. Away from the resonance peak the magnetic fluctuations are isotropic in the energy range studied. The results are consistent with a dominant singlet pairing state with s^{\pm} symmetry, with a possible minority component of different symmetry.Comment: 5 pages, 4 figure

Diffusion in pores and its dependence on boundary conditions

We study the influence of the boundary conditions at the solid liquid interface on diffusion in a confined fluid. Using an hydrodynamic approach, we compute numerical estimates for the diffusion of a particle confined between two planes. Partial slip is shown to significantly influence the diffusion coefficient near a wall. Analytical expressions are derived in the low and high confinement limits, and are in good agreement with numerical results. These calculations indicate that diffusion of tagged particles could be used as a sensitive probe of the solid-liquid boundary conditions.Comment: soumis \`a J.Phys. Cond. Matt. special issue on "Diffusion in Liquids, Polymers, Biophysics and Chemical Dynamics

The Assembly of the Red Sequence at z ~ 1: The Color and Spectral Properties of Galaxies in the Cl1604 Supercluster

We investigate the properties of the 525 spectroscopically confirmed members of the Cl1604 supercluster at z ~ 0.9 as part of the Observations of Redshift Evolution in Large Scale Environments survey. In particular, we focus on the photometric, stellar mass, morphological, and spectral properties of the 305 member galaxies of the eight clusters and groups that comprise the Cl1604 supercluster. Using an extensive Keck Low-Resolution Imaging Spectrometer (LRIS)/DEep Imaging Multi-Object Spectrograph (DEIMOS) spectroscopic database in conjunction with ten-band ground-based, Spitzer, and Hubble Space Telescope imaging, we investigate the buildup of the red sequence in groups and clusters at high redshift. Nearly all of the brightest and most massive red-sequence galaxies present in the supercluster environment are found to lie within the bounds of the cluster and group systems, with a surprisingly large number of such galaxies present in low-mass group systems. Despite the prevalence of these red-sequence galaxies, we find that the average cluster galaxy has a spectrum indicative of a star-forming galaxy, with a star formation rate between those of z ~ 1 field galaxies and moderate-redshift cluster galaxies. The average group galaxy is even more active, exhibiting spectral properties indicative of a starburst. The presence of massive, red galaxies and the high fraction of starbursting galaxies present in the group environment suggest that significant processing is occurring in group environments at z ~ 1 and earlier. There is a deficit of low-luminosity red-sequence galaxies in all Cl1604 clusters and groups, suggesting that such galaxies transition to the red sequence at later times. Extremely massive (~10^(12)M_☉) red-sequence galaxies routinely observed in rich clusters at z ~ 0 are also absent from the Cl1604 clusters and groups. We suggest that such galaxies form at later times through merging processes. There are significant populations of transition galaxies at intermediate stellar masses (log(M_*)=10.25-10.75) present in the group and cluster environments, suggesting that this range is important for the buildup of the red-sequence mass function at z ~ 1. Through a comparison of the transitional populations present in the Cl1604 cluster and group systems, we find evidence that massive blue-cloud galaxies are quenched earliest in the most dynamically relaxed systems and at progressively later times in dynamically unrelaxed systems

Spin Waves in Striped Phases

In many antiferromagnetic, quasi-two-dimensional materials, doping with holes leads to "stripe" phases, in which the holes congregate along antiphase domain walls in the otherwise antiferromagnetic texture. Using a suitably parametrized two-dimensional Heisenberg model on a square lattice, we study the spin wave spectra of well-ordered spin stripes, comparing bond-centered antiphase domain walls to site-centered antiphase domain walls for a range of spacings between the stripes and for stripes both aligned with the lattice ("vertical") and oriented along the diagonals of the lattice ("diagonal"). Our results establish that there are qualitative differences between the expected neutron scattering responses for the bond-centered and site-centered cases. In particular, bond-centered stripes of odd spacing generically exhibit more elastic peaks than their site-centered counterparts. For inelastic scattering, we find that bond-centered stripes produce more spin wave bands than site-centered stripes of the same spacing and that bond-centered stripes produce rather isotropic low energy spin wave cones for a large range of parameters, despite local microscopic anisotropy. We find that extra scattering intensity due to the crossing of spin wave modes (which may be linked to the "resonance peak" in the cuprates) is more likely for diagonal stripes, whether site- or bond-centered, whereas spin wave bands generically repel, rather than cross, when stripes are vertical.Comment: 12 pages, 12 figures, for some high-res.pics, see http://physics.bu.edu/~yaodx/spinwave/spinw.htm

Markerless Escherichia coli rrn Deletion Strains for Genetic Determination of Ribosomal Binding Sites

Single-copy rrn strains facilitate genetic ribosomal studies in Escherichia coli. Consecutive markerless deletion of rrn operons resulted in slower growth upon inactivation of the fourth copy, which was reversed by supplying transfer RNA genes encoded in rrn operons in trans. Removal of the sixth, penultimate rrn copy led to a reduced growth rate due to limited rrn gene dosage. Whole-genome sequencing of variants of single-copy rrn strains revealed duplications of large stretches of genomic DNA. The combination of selective pressure, resulting from the decreased growth rate, and the six identical remaining scar sequences, facilitating homologous recombination events, presumably leads to elevated genomic instability

Weak Lensing Detection of Cl 1604+4304 at z = 0.90

We present a weak lensing analysis of the high-redshift cluster Cl 1604+4304. At z=0.90, this is the highest-redshift cluster yet detected with weak lensing. It is also one of a sample of high-redshift, optically-selected clusters whose X-ray temperatures are lower than expected based on their velocity dispersions. Both the gas temperature and galaxy velocity dispersion are proxies for its mass, which can be determined more directly by a lensing analysis. Modeling the cluster as a singular isothermal sphere, we find that the mass contained within projected radius R is 3.69+-1.47 * (R/500 kpc) 10^14 M_odot. This corresponds to an inferred velocity dispersion of 1004+-199 km/s, which agrees well with the measured velocity dispersion of 989+98-76 km/s (Gal & Lubin 2004). These numbers are higher than the 575+110-85 km/s inferred from Cl 1604+4304 X-ray temperature, however all three velocity dispersion estimates are consistent within ~ 1.9 sigma.Comment: Revised version accepted for publication in AJ (January 2005). 2 added figures (6 figures total

Burning by numbers: A pilot study using quantitative petrography in the analysis of heat-induced alteration in burned bone

In the past, experimental research into the histomorphological examination of burned human bone has led to the creation of a criterion for assessing burning intensity, which can be used to infer firing conditions in both archaeological and forensic contexts. Current methods visually compare the microscopic alterations in burned bone with modern bone samples fired at known temperatures and durations. Despite the benefits of this approach, it is hindered by the use of qualitative analysis, which is subject to the expertise of the examiner. This paper reviews previous histomorphological studies of burned bone and presents a new protocol for producing burned bone thin-sections. It also introduces quantitative petrography as an alternative, statistical method for categorising burning intensity. Four categories of burning intensity were calculated based on the quantified heat-induced changes identified in a pilot study examining burned porcine bone. These categories were consistent with those produced using more traditional qualitative methods, demonstrating that the results produced in this pilot study are reliable. An inter-observer study showed the repeatability of this new method by both anthropologists and non-anthropologists

Towards the development of data governance standards for using clinical free-text data in health research: a position paper

Background: Free-text clinical data (such as outpatient letters or nursing notes) represent a vast, untapped source of rich information that, if more accessible for research, would clarify and supplement information coded in structured data fields. Data usually need to be de-identified or anonymised before they can be reused for research, but there is a lack of established guidelines to govern effective de-identification and use of free-text information and avoid damaging data utility as a by-product. / Objective: We set out to work towards data governance standards to integrate with existing frameworks for personal data use, to enable free-text data to be used safely for research for patient/public benefit. / Methods: We outlined (UK) data protection legislation and regulations for context, and conducted a rapid literature review and UK-based case studies to explore data governance models used in working with free-text data. We also engaged with stakeholders including text mining researchers and the general public to explore perceived barriers and solutions in working with clinical free-text. / Results: We propose a set of recommendations, including the need: for authoritative guidance on data governance for the reuse of free-text data; to ensure public transparency in data flows and uses; to treat de-identified free-text as potentially identifiable with use limited to accredited data safe-havens; and, to commit to a culture of continuous improvement to understand the relationships between efficacy of de-identification and re-identification risks, so this can be communicated to all stakeholders. / Conclusions: By drawing together the findings of a combination of activities, our unique study has added new knowledge towards the development of data governance standards for the reuse of clinical free-text data for secondary purposes. Whilst working in accord with existing data governance frameworks, there is a need for further work to take forward the recommendations we have proposed, with commitment and investment, to assure and expand the safe reuse of clinical free-text data for public benefit