506 research outputs found
Seasonally loaded waste stabilisation ponds: a novel application for intermittent discharge
This research examined the use of a single facultative pond for treatment of an intermittent discharge from a UK campsite. The system was monitored over an 11-month period to determine the optimum time for discharge in terms of quality standards. The results showed that based on organic strength, discharge was possible in winter between November and March but February was the optimum to meet nutrient and suspended solids requirements. The pond showed rapid acclimatisation to the influent wastewater, with biochemical oxygen demand removal rates during the filling period of around 60 kg ha?1 day?1 and removal efficiencies of ?95% after maturation. The system proved simple to operate. A major design factor is the requirement for storage of net incoming precipitation, which may provide dilution of residual pollutants but requires additional system capacity.<br/
Operation and recovery of a seasonally-loaded UK waste stabilisation pond system
An intermittent discharge waste stabilisation pond system was trialled for treatment of a seasonal wastewater load from a campsite. The system showed rapid acclimatisation to incoming load, with chlorophyll-a exceeding 700 mg l?1 within 2 weeks and filtered and unfiltered effluent biochemical oxygen demand below 20 and 30 mg l?1 respectively. Good performance continued for some weeks, after which photosynthetic oxygenation capacity in the first pond was seriously impaired by a shock loading believed to include fatty material. Inflow to the system was suspended and a surface film was broken up, after which the pond recovered within an 8-day period. Laboratory experiments indicated that interventions such as artificial aeration and dilution with effluent had no beneficial effect although mixing may have increased the rate of recovery
Carmichael meets chebotarev
For any finite Galois extension K of ℚ and any conjugacy class C in Gal(K=ℚ), we show that there exist infinitely many Carmichael numbers composed solely of primes for which the associated class of Frobenius automorphisms is C. This result implies that for every natural number n there are infinitely many Carmichael numbers of the form a2 + nb 2 with a; b ε Z. © Canadian Mathematical Society 2012
Waring's problem for Beatty sequences and a local to global principle
We investigate in various ways the representation of a large natural number N as a sum of s positive k-th powers of numbers from a fixed Beatty sequence. Inter alia, a very general form of the local to global principle is established in additive number theory. Although the proof is very short, it depends on a deep theorem of M. Kneser. © Société Arithmétique de Bordeaux, 2014, tous droits réservés
On the Non-renormalization of the AdS Radius
We show that the relation between the 't Hooft coupling and the radius of AdS
is not renormalized at one-loop in the sigma model perturbation theory. We
prove this by computing the quantum effective action for the superstring on
AdS_5 x S^5 and showing that it does not receive any finite alpha' corrections.
We also show that the central charge of the interacting worldsheet conformal
field theory vanishes at one-loop.Comment: 13 pages, harvmac. v2: refs added, version to be published on JHE
Superficial geology and hydrogeological domains between Durham and Darlington. Phase 1, (Durham South)
The North East Region’s Groundwater Modelling Strategy has identified the need for the
development of a conceptual model for the Magnesian Limestone aquifer. In line with the
Environment Agency R&D Technical Report W214 (Environment Agency Framework for
Groundwater Resources Conceptual and Numerical Modelling), a scoping study was produced,
that identified areas of uncertainty and work required for the development of the conceptual
model.
The purpose of this project is to give the Environment Agency (EA) a regional understanding of
the geology and hydrogeology of the Magnesian Limestone and overlying superficial deposits in
the North East Region, using information presently held by the British Geological Survey (BGS).
This report contributes to the conceptual model and understanding of the Magnesian Limestone
aquifer.
There is uncertainty in the amount of recharge that the Magnesian Limestone receives from
rainfall. The project is designed to gain a greater understanding of the geology of the superficial
deposits and their hydrogeological properties. These are the key factors for the calculation of
recharge to the Magnesian Limestone aquifer from rainfall. This element of the conceptual
model is essential in understanding the potential water resource available within this aquifer
Superficial geology and hydrogeological domains between Durham and Darlington. Phase 2, (Durham North)
The North East Region’s Groundwater Modelling Strategy has identified the need for the
development of a conceptual model for the Magnesian Limestone aquifer. In line with the
Environment Agency R&D Technical Report W214 (Environment Agency Framework for
Groundwater Resources Conceptual and Numerical Modelling), a scoping study was produced,
that identified areas of uncertainty and work required for the development of the conceptual
model.
The purpose of this project is to give the Environment Agency (EA) a regional understanding of
the geology and hydrogeology of the Magnesian Limestone and overlying superficial deposits in
the North East Region, using information held by the British Geological Survey (BGS). This
report contributes to the conceptual model and understanding of the Magnesian Limestone
aquifer.
There is uncertainty in the amount of recharge that the Magnesian Limestone receives from
rainfall. The project is designed to gain a greater understanding of the geology of the superficial
deposits and their hydrogeological properties. These are the key factors for the calculation of
recharge to the Magnesian Limestone aquifer from rainfall. This element of the conceptual
model is essential in understanding the potential water resource available within this aquifer
Semiclassical quantization of rotating superstring in AdS_5 x S^5
Motivated by recent proposals in hep-th/0202021 and hep-th/0204051 we develop
semiclassical quantization of superstring in . We start with a
classical solution describing string rotating in and boosted along
large circle of . The energy of the classical solution is a function
of the spin and the momentum (R-charge) which interpolates between the
limiting cases S=0 and J=0 considered previously. We derive the corresponding
quadratic fluctuation action for bosonic and fermionic fields from the GS
string action and compute the string 1-loop (large \lambda= {R^4\over \a'^2})
correction to the classical energy spectrum in the sector. We find that
the 1-loop correction to the ground-state energy does not cancel for non-zero
. For large it scales as , i.e. as the classical term, with no
higher powers of appearing. This supports the conjecture made in
hep-th/0204051 that the classical scaling can be interpolated
to weak coupling to reproduce the corresponding operator anomalous dimension
behaviour in gauge theory.Comment: harvmac, 35p. v2,3: minor corrections; v4: added remarks about
higher-loop corrections in section 4 and an argument suggesting the absence
of higher than log S corrections to the energy to all orders in string
tension in section 6.1; v5: factor 1/2 misprints corrected in eqs. (6.6) and
(6.8) and thus in (6.5) and (6.9
A Note on (Meta)stable Brane Configurations in MQCD
We examine the M-theory version of SQCD which is known as MQCD. In the IIA
limit, this theory appears to have a supersymmetry-breaking brane configuration
which corresponds to the meta-stable state of N=1 SU(Nc) SQCD. However, the
behavior at infinity of this non-supersymmetric brane construction differs from
that of the supersymmetric ground state of MQCD. We interpret this to mean that
it is not a meta-stable state in MQCD, but rather a state in another theory.
This provides a concrete example of the fact that, while MQCD accurately
describes the supersymmetric features of SCQD, it fails to reproduce its
non-supersymmetric features (such as meta-stable states) not only
quantitatively but also qualitatively.Comment: 30 pages, 7 figures, harvmac. v2 typo correcte
Vortex Holography
We show that the Abelian Higgs field equations in the four dimensional anti
de Sitter spacetime have a vortex line solution. This solution, which has
cylindrical symmetry in AdS, is a generalization of the flat spacetime
Nielsen-Olesen string. We show that the vortex induces a deficit angle in the
AdS spacetime that is proportional to its mass density. Using the AdS/CFT
correspondence, we show that the mass density of the string is uniform and dual
to the discontinuity of a logarithmic derivative of correlation function of the
boundary scalar operator.Comment: LaTeX, 20 pages, 4 eps figures, references and two paragraphs added,
to appear in Nucl. Phys.
- …