20 research outputs found
Centrally extended symmetry algebra of asymptotically Goedel spacetimes
We define an asymptotic symmetry algebra for three-dimensional Goedel
spacetimes supported by a gauge field which turns out to be the semi-direct sum
of the diffeomorphisms on the circle with two loop algebras. A class of fields
admitting this asymptotic symmetry algebra and leading to well-defined
conserved charges is found. The covariant Poisson bracket of the conserved
charges is then shown to be centrally extended to the semi-direct sum of a
Virasoro algebra and two affine algebras.Comment: 12 pages, sign mistake corrected in the central charge, takes
precedence over published versio
Solar-powered Water Purification and Community Development in Haiti\u27s Artibonite Valley
In May 2017, the Project Haiti team of two faculty and eleven students from Embry-Riddle Aeronautical University, Daytona Beach, Florida, working together with a professor and translator from the Universite d’Etat d’Haiti, designed and installed a solar-powered water purification system in the village of Drouin, Artibonite Department, Haiti. This region has been at the epicenter of the post-2010 cholera epidemic that has infected hundreds of thousands and killed many thousands. There has been no reliably safe drinking water in the region. The Haitian operators were empowered with ongoing maintenance and operation of the system, as well as the micro-business operations. Partnership with Haitians and the long-term partnering NGO (non-governmental organization) is a critical enabling aspect that improves sustainability of this community development effort
Microscopics of Extremal Kerr from Spinning M5 Branes
We show that the spinning magnetic one-brane in minimal five-dimensional
supergravity admits a decoupling limit that interpolates smoothly between a
self-dual null orbifold of AdS_3 \times S^2 and the near-horizon limit of the
extremal Kerr black hole times a circle. We use this interpolating solution to
understand the field theory dual to spinning M5 branes as a deformation of the
Discrete Light Cone Quantized (DLCQ) Maldacena-Stominger-Witten (MSW) CFT. In
particular, the conformal weights of the operators dual to the deformation
around AdS_3 \times S^2 are calculated. We present pieces of evidence showing
that a CFT dual to the four-dimensional extremal Kerr can be obtained from the
deformed MSW CFT.Comment: 5 page
Central Charges in Extreme Black Hole/CFT Correspondence
The Kerr/CFT correspondence has been recently broadened to the general
extremal black holes under the assumption that the central charges from the
non-gravitational fields vanish. To confirm this proposal, we derive the
expression of the conserved charges in the Einstein-Maxwell-scalar theory with
topological terms in four and five dimensions and check that the above
assumption was correct. Combining the computed central charge with the expected
form of the temperature, the Bekenstein-Hawking entropy of the general extremal
black holes in four and five dimensions can be reproduced by using the Cardy
formula.Comment: 20 pages, v2:references added, published in JHE
A General Black String and its Microscopics
Using G2(2) dualities we construct the most general black string solution of
minimal five-dimensional ungauged supergravity. The black string has five
independent parameters, namely, the magnetic one-brane charge, smeared electric
zero-brane charge, boost along the string direction, energy above the BPS
bound, and rotation in the transverse space. In one extremal limit it reduces
to the three parameter supersymmetric string of five-dimensional minimal
supergravity; in another extremal limit it reduces to the three parameter
non-supersymmetric extremal string of five-dimensional minimal supergravity. It
also admits an extremal limit when it has maximal rotation in the
four-dimensional transverse space. The decoupling limit of our general black
string is a BTZ black hole times a two sphere. The macroscopic entropy of the
string is reproduced by the Maldacena-Strominger-Witten CFT in appropriate
ranges of the parameters. When the pressureless condition is imposed, our
string describes the infinite radius limit of the most general class of black
rings of minimal supergravity. We discuss implications our solution has for
extremal and non-extremal black rings of minimal supergravity.Comment: 35 pages; 3 figures; v2 section 4.1.1 rewritten + minor changes + ref
adde
The relativistic fluid dual to vacuum Einstein gravity
We present a construction of a (d+2)-dimensional Ricci-flat metric
corresponding to a (d+1)-dimensional relativistic fluid, representing
holographically the hydrodynamic regime of a (putative) dual theory. We show
how to obtain the metric to arbitrarily high order using a relativistic
gradient expansion, and explicitly carry out the computation to second order.
The fluid has zero energy density in equilibrium, which implies
incompressibility at first order in gradients, and its stress tensor (both at
and away from equilibrium) satisfies a quadratic constraint, which determines
its energy density away from equilibrium. The entire dynamics to second order
is encoded in one first order and six second order transport coefficients,
which we compute. We classify entropy currents with non-negative divergence at
second order in relativistic gradients. We then verify that the entropy current
obtained by pulling back to the fluid surface the area form at the null horizon
indeed has a non-negative divergence. We show that there are distinct
near-horizon scaling limits that are equivalent either to the relativistic
gradient expansion we discuss here, or to the non-relativistic expansion
associated with the Navier-Stokes equations discussed in previous works. The
latter expansion may be recovered from the present relativistic expansion upon
taking a specific non-relativistic limit.Comment: 29 pages, 1 figure; v2: added comments and references, published
versio
A Microcosm of Sustainable Practices: Honors Program and Project Haiti Partnership with Derbyshire Community Garden
The Embry-Riddle Honors Program has been partnering with and growing the Derbyshire Community Garden consistently/perpetually for the past two years, playing an increasingly managerial role. We emphasize regenerative practices, from planting a wide variety of heirloom organic seeds; to vermicomposting; to fully avoiding any chemical fertilizers, herbicides, and pesticides; to operating a Saturday produce market on site, supporting local residents in this food-insecure neighborhood with fresh, organic, nutrient-rich foods. Partnering with ERAU’s Project Haiti, the Haiti team has diverted some of its Ford Campus Community Challenge grant award (due to the team’s inability to travel to Haiti, chiefly due to social/political instability) to install an 18 panel ground-mounted solar array inside the Garden space, providing all of the power needed for Garden operation…plus reducing the electrical grid reliance of the adjoining Derbyshire Community Center by an estimated 25% monthly. We are moving closer to “closed loop system,” overall.
This involvement and partnership highlights the following: Localized, high-caliber, individualized food production versus full reliance on long, complex (and vulnerable) supply chains Regenerative, organic agricultural practices versus “Green Revolution” industrialized, chemical-intensive agriculture Biodiversity and seed-saving/sharing versus the narrowing range of seed made available via large-scale, industrial agriculture/monoculture Attention to building healthy soil as a key to overall health, versus the extractive practices commonly in place Clean, sustainable sources of energy and the link between solar and agriculture (agrivoltaics) Re/invigorating community connections across generational, gender, racial, national, and economic “boundaries”
Combined, these now-established features at Derbyshire open many further opportunities for on-site education regarding localized management and control, environmental stewardship, community impact and engagement, and environmental and human health