916 research outputs found
Management practices for the amelioration of urban stormwater
AbstractUrban runoff has been identified as a non-point source (NPS) contributor. The most effective mechanism for controlling urban NPS pollution is to reduce the amount of runoff through infiltration and storage on the landscape. Traditional infiltration best management practices (BMPs) have lacked long-term effectiveness because of clogging. The addition of vegetation to the system enhances the longevity of infiltration BMPs by enhancing soil structure. In order to better understand the design and function of vegetated, infiltration-based BMPs, Kansas State University is monitoring several sites in Kansas. Results indicate that vegetation enhances the ability of stormwater systems to store water and reduce down channel erosion and flooding
Perceived benefits of complementary and alternative medicine: A whole systems research perspective
The purpose of this study was to examine the benefits associated with complementary and alternative medicine (CAM) treatments from the patientsâ perspective using a whole systems research approach as a guiding framework. We conducted five focus groups of six to eight participants each, with users of CAM recruited through experienced CAM providers and clinics. Eligible participants were aged 21 or older, had used CAM in the last 12 months, and believed the treatment to be beneficial. The focus group discussions were digitally recorded, transcribed, and analyzed through a qualitative content analysis. Responses were inductively coded for common themes, and then placed into broader conceptual categories reflecting the CAM outcome domains suggested by Verhoef and colleagues. Participants described physical health benefits including symptom relief and improved function, and positive psychological benefits such as improved coping and resilience. Social health benefits that arose from the positive aspects of the patient-practitioner relationship were also reported, including support and advocacy. In addition, participants identified empowerment, increased hope and spiritual growth as results of receiving CAM treatments. A new behavioral health outcome domain emerged as participants reported that CAM use had fostered behavioral changes such as increased exercise, smoking cessation and improving their diets. These patient-reported benefits of CAM treatment are consistent with the outcome model proposed by Verhoef and colleagues, and extend this model by identifying a new outcome domainâbehavioral health outcome. The findings provide insight and direction for the development of outcome and process measures to evaluate CAM treatment effects
EYM equations in the presence of q-stars
We study Einstein-Yang-Mills equations in the presence of gravitating
non-topological soliton field configurations, of q-ball type. We produce
numerical solutions, stable with respect to gravitational collapse and to
fission into free particles, and we study the effect of the field strength and
the eigen-frequency to the soliton parameters. We also investigate the
formation of such soliton stars when the spacetime is asymptotically anti de
Sitter.Comment: 11 pages, to appear in Phys. Rev.
Mechanisms of Spontaneous Current Generation in an Inhomogeneous d-Wave Superconductor
A boundary between two d-wave superconductors or an s-wave and a d-wave
superconductor generally breaks time-reversal symmetry and can generate
spontaneous currents due to proximity effect. On the other hand, surfaces and
interfaces in d-wave superconductors can produce localized current-carrying
states by supporting the T-breaking combination of dominant and subdominant
order parameters. We investigate spontaneous currents in the presence of both
mechanisms and show that at low temperature, counter-intuitively, the
subdominant coupling decreases the amplitude of the spontaneous current due to
proximity effect. Superscreening of spontaneous currents is demonstrated to be
present in any d-d (but not s-d) junction and surface with d+id' order
parameter symmetry. We show that this supercreening is the result of
contributions from the local magnetic moment of the condensate to the
spontaneous current.Comment: 4 pages, 5 figures, RevTe
Constraining the primordial spectrum of metric perturbations from gravitino and moduli production
We consider the production of gravitinos and moduli fields from quantum
vacuum fluctuations induced by the presence of scalar metric perturbations at
the end of inflation. We obtain the corresponding occupation numbers, up to
first order in perturbation theory, in terms of the power spectrum of the
metric perturbations. We compute the limits imposed by nucleosynthesis on the
spectral index for different models with constant . The results show
that, in certain cases, such limits can be as strong as , which is
more stringent than those coming from primordial black hole production.Comment: 16 pages, LaTeX, 5 figures. Corrected figures, new references
included. Final version to appear in Phys. Rev.
Primordial black hole production due to preheating
During the preheating process at the end of inflation the amplification of
field fluctuations can lead to the amplification of curvature perturbations. If
the curvature perturbations on small scales are sufficiently large, primordial
black holes (PBHs) will be overproduced. In this paper we study PBH production
in the two-field preheating model with quadratic inflaton potential. We show
that for many values of the inflaton mass m, and coupling g, small scale
perturbations will be amplified sufficiently, before backreaction can shut off
preheating, so that PBHs will be overproduced during the subsequent radiation
dominated era.Comment: 5 pages, 3 eps figures. Minor changes to match version to appear in
PRD as a rapid communicatio
Orientifolding the conifold
In this paper we study the N=1 supersymmetric field theories realized on the
world-volume of type IIB D3-branes sitting at orientifolds of non-orbifold
singularities (conifold and generalizations). Several chiral models belong to
this family of theories. These field theories have a T-dual realization in
terms of type IIA configurations of relatively rotated NS fivebranes, D4-branes
and orientifold six-planes, with a compact direction, along which the
D4-branes have finite extent. We compute the spectrum on the D3-branes directly
in the type IIB picture and match the resulting field theories with those
obtained in the type IIA setup, thus providing a non-trivial check of this
T-duality. Since the usual techniques to compute the spectrum of the model and
check the cancellation of tadpoles, cannot be applied to the case orientifolds
of non-orbifold singularities, we use a different approach, and construct the
models by partially blowing-up orientifolds of C^3/(Z_2 x Z_2) and C^3/(Z_2 x
Z_3) orbifolds.Comment: 52 pages, Latex 7 eps figure
Quasiclassical Theory of Spontaneous Currents at Surfaces and Interfaces of d-Wave Superconductors
We investigate the properties of spontaneous currents generated at surfaces
and interfaces of d-wave superconductors using the self-consistent
quasiclassical Eilenberger equations. The influence of the roughness and
reflectivity of the boundaries on the spontaneous current are studied. We show
that these have very different effects at the surfaces compared to the
interfaces, which reflects the different nature of the time reversal symmetry
breaking states in these two systems. We find a signature of the ``anomalous
proximity effect'' at rough d-wave interfaces. We also show that the existence
of a subdominant order parameter, which is necessary for time reversal symmetry
breaking at the surface, suppresses the spontaneous current generation due to
proximity effect at the interface between two superconductors. We associate
orbital moments to the spontaneous currents to explain the ``superscreening''
effect, which seems to be present at all ideal d-wave surfaces and interfaces,
where d_{xy} is the favorite subdominant symmetry.Comment: 13 pages, 17 postscript figure
Mirror Symmetry and Other Miracles in Superstring Theory
The dominance of string theory in the research landscape of quantum gravity
physics (despite any direct experimental evidence) can, I think, be justified
in a variety of ways. Here I focus on an argument from mathematical fertility,
broadly similar to Hilary Putnam's 'no miracles argument' that, I argue, many
string theorists in fact espouse. String theory leads to many surprising,
useful, and well-confirmed mathematical 'predictions' - here I focus on mirror
symmetry. These predictions are made on the basis of general physical
principles entering into string theory. The success of the mathematical
predictions are then seen as evidence for framework that generated them. I
attempt to defend this argument, but there are nonetheless some serious
objections to be faced. These objections can only be evaded at a high
(philosophical) price.Comment: For submission to a Foundations of Physics special issue on "Forty
Years Of String Theory: Reflecting On the Foundations" (edited by G. `t
Hooft, E. Verlinde, D. Dieks and S. de Haro)
Flux-induced SUSY-breaking soft terms on D7-D3 brane systems
We study the effect of RR and NSNS 3-form fluxes on the effective action of
the worldvolume fields of Type IIB D7/D3-brane configurations. The D7-branes
wrap 4-cycles on a local Calabi-Yau geometry. This is an extension of previous
work on hep-th/0311241, where a similar analysis was applied to the case of
D3-branes. Our present analysis is based on the D7- and D3-brane
Dirac-Born-Infeld and Chern-Simons actions, and makes full use of the
R-symmetries of the system, which allow us to compute explicitly results for
the fields lying at the D3-D7 intersections. A number of interesting new
properties appear as compared to the simpler case of configurations with only
D3-branes. As a general result one finds that fluxes stabilize some or all of
the D7-brane moduli. We argue that this is important for the problem of
stabilizing Kahler moduli through non-perturbative effects in KKLT-like vacua.
We also show that (0,3) imaginary self-dual fluxes, which lead to
compactifications with zero vacuum energy, give rise to SUSY-breaking soft
terms including gaugino and scalar masses, and trilinear terms. Particular
examples of chiral MSSM-like models of this class of vacua, based on D3-D7
brane systems at orbifold singularities are presented.Comment: 58 pages, no figures; v2: numerical factor in section 7.2 correcte
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