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Results of an aqueous source term model for a radiological risk assessment of the Drigg LLW Site, U.K.
A radionuclide source term model has been developed which simulates the biogeochemical evolution of the Drigg low level waste (LLW) disposal site. The DRINK (DRIgg Near field Kinetic) model provides data regarding radionuclide concentrations in groundwater over a period of 100,000 years, which are used as input to assessment calculations for a groundwater pathway. The DRINK model also provides input to human intrusion and gaseous assessment calculations through simulation of the solid radionuclide inventory. These calculations are being used to support the Drigg post closure safety case. The DRINK model considers the coupled interaction of the effects of fluid flow, microbiology, corrosion, chemical reaction, sorption and radioactive decay. It represents the first direct use of a mechanistic reaction-transport model in risk assessment calculations
Systematic Study of Theories with Quantum Modified Moduli
We begin the process of classifying all supersymmetric theories with quantum
modified moduli. We determine all theories based on a single SU or Sp gauge
group with quantum modified moduli. By flowing among theories we have
calculated the precise modifications to the algebraic constraints that
determine the moduli at the quantum level. We find a class of theories, those
with a classical constraint that is covariant but not invariant under global
symmetries, that have a singular modification to the moduli, which consists of
a new branch.Comment: 21 pages, ReVTeX (or Latex, etc), corrected typos and cQMM discusio
Exact isotropic cosmologies with local fractal number counts
We construct an exact relativistic cosmology in which an inhomogeneous but
isotropic local region has fractal number counts and matches to a homogeneous
background at a scale of the order of Mpc. We show that Einstein's
equations and the matching conditions imply either a nonlinear Hubble law or a
very low large-scale density.Comment: revised version, to appear Class. Q. Grav.; minor corrections
following eqn 16, additional comments on relation to other work, some new
reference
Axial Symmetry and Rotation in the SiO Maser Shell of IK Tauri
We observed v=1, J=1-0 43-GHz SiO maser emission toward the Mira variable IK
Tauri (IK Tau) using the Very Long Baseline Array (VLBA). The images resulting
from these observations show that SiO masers form a highly elliptical ring of
emission approximately 58 x 32 mas with an axial ratio of 1.8:1. The major axis
of this elliptical distribution is oriented at position angle of ~59 deg. The
line-of-sight velocity structure of the SiO masers has an apparent axis of
symmetry consistent with the elongation axis of the maser distribution.
Relative to the assumed stellar velocity of 35 km/s, the blue- and red-shifted
masers were found to lie to the northwest and southeast of this symmetry axis
respectively. This velocity structure suggests a NW-SE rotation of the SiO
maser shell with an equatorial velocity, which we determine to be ~3.6 km/s.
Such a NW-SE rotation is in agreement with a circumstellar envelope geometry
invoked to explain previous water and OH maser observations. In this geometry,
water and OH masers are preferentially created in a region of enhanced density
along the NE-SW equator orthogonal to the rotation/polar axis suggested by the
SiO maser velocities.Comment: 17 Pages, 4 figures (2 color); accepted for publication in Ap
Matching Spherical Dust Solutions to Construct Cosmological Models
Conditions for smooth cosmological models are set out and applied to
inhomogeneous spherically symmetric models constructed by matching together
different Lemaitre-Tolman-Bondi solutions to the
Einstein field equations. As an illustration the methods are applied to a
collapsing dust sphere in a curved background. This describes a region which
expands and then collapses to form a black hole in an
Einstein de Sitter background. We show that in all such models if there is no
vacuum region then the singularity must go on accreting matter for an infinite
LTB time.Comment: 13 pages, Revtex; to appear Gen. Rel. Gra
The enrichment of an alkaliphilic biofilm consortia capable of the anaerobic degradation of isosaccharinic acid from cellulosic materials incubated within an anthropogenic, hyperalkaline environment.
Anthropogenic hyper-alkaline sites provide an environment that is analogous to proposed cementitious geological disposal facilities (GDF) for radioactive waste. Under anoxic, alkaline conditions cellulosic wastes will hydrolyse to a range of cellulose degradation products (CDP) dominated by isosaccharinic acids (ISA). In order to investigate the potential for microbial activity in a cementitious GDF, cellulose samples were incubated in the alkaline (âŒpH 12), anaerobic zone of a lime kiln waste site. Following retrieval, these samples had undergone partial alkaline hydrolysis and were colonised by a Clostridia dominated biofilm community, where hydrogenotrophic, alkaliphilic methanogens were also present. When these samples were used to establish an alkaline CDP fed microcosm, the community shifted away from Clostridia, methanogens became undetectable and a flocculate community dominated by Alishewanella sp. established. These flocs were composed of bacteria embedded in polysaccharides and protein stabilised by extracellular DNA. This community was able to degrade all forms of ISA with >60% of the carbon flow being channelled into extracellular polymeric substance (EPS) production. This study demonstrated that alkaliphilic microbial communities can degrade the CDP associated with some radioactive waste disposal concepts at pH 11. These communities divert significant amounts of degradable carbon to EPS formation, suggesting that EPS has a central role in the protection of these communities from hyper-alkaline conditions
Search for LBV Candidates in the M33 Galaxy
A total of 185 luminous blue variable (LBV) candidates with V < 18.5 and B-V
< 0.35 are selected based on the photometrical Survey of Local Group Galaxies
made by P. Massey et al. 2006. The candidates were selected using aperture
photometry of H-alpha images. The primary selection criterion is that the
prospective candidate should be a blue star with H-aplha emission. In order not
to miss appreciably reddened LBV candidates, we compose an additional list of
25 presumably reddened (0.35 < B-V < 1.2, V < 18.5) emission star candidates. A
comparison with the list of known variables in the M33 galaxy showed 29% of our
selected candidates to be photometrically variable. We also find our list to
agree well with the lists of emission-line objects obtained in earlier papers
using different methods.Comment: 6 figure
Deterministic delivery of remote entanglement on a quantum network
Large-scale quantum networks promise to enable secure communication,
distributed quantum computing, enhanced sensing and fundamental tests of
quantum mechanics through the distribution of entanglement across nodes. Moving
beyond current two-node networks requires the rate of entanglement generation
between nodes to exceed their decoherence rates. Beyond this critical
threshold, intrinsically probabilistic entangling protocols can be subsumed
into a powerful building block that deterministically provides remote entangled
links at pre-specified times. Here we surpass this threshold using diamond spin
qubit nodes separated by 2 metres. We realise a fully heralded single-photon
entanglement protocol that achieves entangling rates up to 39 Hz, three orders
of magnitude higher than previously demonstrated two-photon protocols on this
platform. At the same time, we suppress the decoherence rate of remote
entangled states to 5 Hz by dynamical decoupling. By combining these results
with efficient charge-state control and mitigation of spectral diffusion, we
are able to deterministically deliver a fresh remote state with average
entanglement fidelity exceeding 0.5 at every clock cycle of 100 ms
without any pre- or post-selection. These results demonstrate a key building
block for extended quantum networks and open the door to entanglement
distribution across multiple remote nodes.Comment: v2 - updated to include relevant citatio
Microbial Community Evolution Is Significantly Impacted by the Use of Calcium Isosaccharinic Acid as an Analogue for the Products of Alkaline Cellulose Degradation
Diasteriomeric isosaccharinic acid (ISA) is an important consideration within safety assessments for the disposal of the United Kingdomsâ nuclear waste legacy, where it may potentially influence radionuclide migration. Since the intrusion of micro-organisms may occur within a disposal concept, the impact of ISA may be impacted by microbial metabolism. Within the present study we have established two polymicrobial consortia derived from a hyperalkaline soil. Here, α-ISA and a diatereomeric mix of ISAsâ were used as a sole carbon source, reflecting two common substrates appearing within the literature. The metabolism of ISA within these two consortia was similar, where ISA degradation resulted in the acetogenesis and hydrogenotrophic methanogenesis. The chemical data obtained confirm that the diastereomeric nature of ISA is likely to have no impact on its metabolism within alkaline environments. High throughput sequencing of the original soil showed a diverse community which, in the presence of ISA allowed for the dominance the Clostridiales associated taxa with Clostridium clariflavum prevalent. Further taxonomic investigation at the genus level showed that there was in fact a significant difference (p = 0.004) between the two community profiles. Our study demonstrates that the selection of carbon substrate is likely to have a significant impact on microbial community composition estimations, which may have implications with respect to a safety assessment of an ILW-GDF
Two New LBV Candidates in the M33 Galaxy
We present two new luminous blue variable (LBV) candidate stars discovered in
the M33 galaxy. We identified these stars (Valeev et al. 2010) as massive star
candidates at the final stages of evolution, presumably with a notable
interstellar extinction. The candidates were selected from the Massey et al.
(2006) catalog based on the following criteria: emission in Halpha, V<18.5 and
0.35<(B-V)<1.2. The spectra of both stars reveal a broad and strong Halpha
emission with extended wings (770 and 1000 km/s). Based on the spectra we
estimated the main parameters of the stars. Object N45901 has a bolometric
luminosity log(L/Lsun)=6.0-6.2 with the value of interstellar extinction
Av=2.3+-0.1. The temperature of the star's photosphere is estimated as
Tstar~13000-15000K its probable mass on the Zero Age Main Sequence is
M~60-80Msun. The infrared excess in N45901 corresponds to the emission of warm
dust with the temperature Twarm~1000K, and amounts to 0.1% of the bolometric
luminosity. A comparison of stellar magnitude estimates from different catalogs
points to the probable variability of the object N45901. Bolometric luminosity
of the second object, N125093, is log(L/Lsun)=6.3-6.6, the value of
interstellar extinction is Av=2.75+-0.15. We estimate its photosphere's
temperature as Tstar~13000-16000K, the initial mass as M~90-120Msun. The
infrared excess in N125093 amounts to 5-6% of the bolometric luminosity. Its
spectral energy distribution reveals two thermal components with the
temperatures Twarm~1000K and Tcold~480K. The [CaII] lines (7291A and 7323A),
observed in LBV-like stars VarA and N93351 in M33, are also present in the
spectrum of N125093. These lines indicate relatively recent gas eruptions and
dust activity linked with them. High bolometric luminosity of these stars and
broad Halpha emissions allow classifying the studied objects as LBV candidates.Comment: 14 pages, 4 figure
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