1,128 research outputs found
Building Monitoring System and Preliminary Results for a Retrofitted Office Building
Existing commercial buildings in the United States consumed 18.42 quadrillion Btus of primary energy in 2008 which amounts to 18.4% of all energy consumed and 78% of all electricity in the United States (DOE 2011). The U.S. Energy Information Administrationâs Commercial Buildings Energy Consumption Survey (EIA 2011) shows a flat energy consumption profile between 1983 and 2003 indicating no real improvement in the aggregate commercial building stock. Buildings less than 100,000 square feet account for 65% of the commercial building floor space (EIA 2011). These buildings fall into three general categories: privately owned, state owned or federally owned and they can be either owner occupied or tenant occupied. According to a recent report, only 25 percent of small building owners plan to make energy efficiency improvements (IFMA 2009). The current state of the building retrofit market incorporates disparate modeling tools that generally do not take into account utility bills, are expensive to populate with data and provide a wide bandwidth of results. Equipment, subsystems, sensors and controls are designed as discrete solutions to narrow problems, and performance is more a matter of meeting individual rating standards than integrated building load profiles. Finally, the construction industry itself is structurally fragmented leading to suboptimal results. Given the preceding, one can only conclude deep energy efficiency retrofits of average existing buildings will be multifaceted and challenging. This paper will explore The Energy Efficient Buildings Hub (EEB Hub) commercial building testbed program designed to: provide researchers with detailed existing building level performance and indoor environmental quality data develop and/or validate existing and new building load models assess dynamic control systems examine current energy auditing practices and develop new strategic asset management practices validate building integrated technology performanc
Skeletal myofiber vascular endothelial growth factor is required for the exercise training-induced increase in dentate gyrus neuronal precursor cells
Exercise signals neurogenesis in the dentate gyrus of the hippocampus. This phenomenon requires vascular endothelial growth factor (VEGF) originating from outside the bloodâbrain barrier, but no cellular source has been identified. Thus, we hypothesized that VEGF produced by skeletal myofibers plays a role in regulating hippocampal neuronal precursor cell proliferation following exercise training. This was tested in adult conditional skeletal myofiberâspecific VEGF geneâablated mice (VEGFHSAâ/â) by providing VEGFHSAâ/â and nonâablated (VEGFf/f) littermates with running wheels for 14 days. Following this training period, hippocampal cerebral blood flow (CBF) was measured by functional magnetic resonance imaging (fMRI), and neuronal precursor cells (BrdU+/Nestin+) were detected by immunofluorescence. The VEGFf/f trained group showed improvements in both speed and endurance capacity in acute treadmill running tests (P < 0.05). The VEGFHSAâ/â group did not. The number of proliferating neuronal precursor cells was increased with training in VEGFf/f (P < 0.05) but not in VEGFHSAâ/â mice. Endothelial cell (CD31+) number did not change in this region with exercise training or skeletal myofiber VEGF gene deletion. However, resting blood flow through the hippocampal region was lower in VEGFHSAâ/â mice, both untrained and trained, than untrained VEGFf/f mice (P < 0.05). An acute hypoxic challenge decreased CBF (P < 0.05) in untrained VEGFf/f, untrained VEGFHSAâ/â and trained VEGFHSAâ/â mice, but not trained VEGFf/f mice. VEGFf/f, but not VEGFHSAâ/â, mice were able to acutely run on a treadmill at an intensity sufficient to increase hippocampus VEGF levels. These data suggest that VEGF expressed by skeletal myofibers may directly or indirectly regulate both hippocampal blood flow and neurogenisis
Nova Sagittarii 1994 #1 (V4332 Sagittarii): The Discovery and Evolution of an Unusual Luminous Red Variable Star
We report photometry and spectroscopy of the evolution of Nova Sagittarii
1994 #1 (V4332 Sagittarii) during outburst. We compare the photometric and
spectral evolution of this outburst to known classes of outbursts -- including
classical novae and outbursts occurring on symbiotic stars -- and find this
object does NOT conform to any known class of outburst. The closest match to
the behavior of this unusual object is M31 RV, an extremely luminous and red
variable object discovered in the bulge of M31 in 1988. However, the temporal
behavior and maximum luminosity of the two events differ by several orders of
magnitude, requiring substantial intrinsic variation if these two events are
members the same type of outburst.
Our model of the spectroscopic evolution of this outburst shows that the
effective temperature cooled from 4400 K to 2300 K over the three month span of
our observations. In combination with line diagnostics in our later spectra,
including [OI] lambda 5577 and the dramatic increase in the Halpha to Hbeta
ratio, we infer the existence of a cool, dense (N_e ~ 10^{8-9} cm^{-3})
envelope that is optically thick in the Hydrogen Balmer recombination lines
(case C). We suggest that a nuclear event in a single star, in which a slow
shock drove the photosphere outwards, can power the observed luminosity
evolution and the emission spectrum.Comment: Accepted for publication in AJ. 24 pages including 8 embedded
postscript figures. Also available at
http://www.astronomy.ohio-state.edu/~martini/pub
The complexity of searching implicit graphs
AbstractThe standard complexity classes of complexity theory do not allow for direct classification of most of the problems solved by heuristic search algorithms. The reason is that, almost always, these are defined in terms of implicit graphs of state or problem reduction spaces, while the standard definitions of all complexity classes are specifically tailored to explicit inputs.To allow for more precise comparisons with standard complexity classes, we introduce here a model for the analysis of algorithms on graphs given by vertex expansion procedures. It is based on previously studied concepts of âsuccinct representationâ techniques, and allows us to prove PSPACE-completeness or EXPTIME-completeness of specific, natural problems on implicit graphs, such as those solved by Aâ, AOâ, and other best-first search strategies
Luminous Blue Variable eruptions and related transients: Diversity of progenitors and outburst properties
We present new light curves and spectra for a number of extragalactic optical
transients or "SN impostors" related to giant eruptions of LBVs, and we provide
a comparative discussion of LBV-like giant eruptions known to date. New data
include photometry and spectroscopy of SNe1999bw, 2000ch, 2001ac, 2002bu,
2006bv, and 2010dn. SN2010dn resembles SN2008S and NGC 300-OT, whereas SN2002bu
shows spectral evolution from a normal LBV at early times to a twin of these
cooler transients at late times. SN2008S, NGC300-OT, and SN2010dn appear to be
special cases of a broader eruptive phenomenon where the progenitor star was
enshrouded by dust. Examining the full sample, SN impostors have range of
timescales from a day to decades, potentially suffering multiple eruptions. The
upper end of the luminosity distribution overlaps with the least luminous SNe.
The low end of the luminosity distribution is poorly defined, and a distinction
between various eruptions is not entirely clear. We discuss observational clues
concerning winds or shocks as the relevant mass-loss mechanism, and we evaluate
possible ideas for physical mechanisms. Although examples of these eruptions
are sufficient to illustrate their diversity, their statistical distribution
will benefit greatly from upcoming transient surveys. Based on the distribution
of eruptions, we propose that SN1961V was not a member of this class of
impostors, but was instead a true core-collapse SNIIn preceded by a giant LBV
eruption. (abridged)Comment: 36(!) journal pages, 16 figures. submitted to MNRAS on october 12.
coments welcome. updated reference
ThermoElectric Transport Properties of a Chain of Quantum Dots with Self-Consistent Reservoirs
We introduce a model for charge and heat transport based on the
Landauer-Buttiker scattering approach. The system consists of a chain of
quantum dots, each of them being coupled to a particle reservoir. Additionally,
the left and right ends of the chain are coupled to two particle reservoirs.
All these reservoirs are independent and can be described by any of the
standard physical distributions: Maxwell-Boltzmann, Fermi-Dirac and
Bose-Einstein. In the linear response regime, and under some assumptions, we
first describe the general transport properties of the system. Then we impose
the self-consistency condition, i.e. we fix the boundary values (T_L,\mu_L) and
(T_R,mu_R), and adjust the parameters (T_i,mu_i), for i = 1,...,N, so that the
net average electric and heat currents into all the intermediate reservoirs
vanish. This condition leads to expressions for the temperature and chemical
potential profiles along the system, which turn out to be independent of the
distribution describing the reservoirs. We also determine the average electric
and heat currents flowing through the system and present some numerical
results, using random matrix theory, showing that these currents are typically
governed by Ohm and Fourier laws.Comment: Minor changes (45 pages
Taking stock of gene therapy for cystic fibrosis
The identification of the cystic fibrosis (CF) gene opened the way for gene therapy. In the ten years since then, proof of principle in vitro and then in animal models in vivo has been followed by numerous clinical studies using both viral and non-viral vectors to transfer normal copies of the gene to the lungs and noses of CF patients. A wealth of data have emerged from these studies, reflecting enormous progress and also helping to focus and define key difficulties that remain unresolved. Gene therapy for CF remains the most promising possibility for curative rather than symptomatic therapy
Free surface flows emerging from beneath a semi-infinite plate with constant vorticity
The free surface flow past a semi-infinite horizontal plate in a finite-depth fluid is considered. It is assumed that the fluid is incompressible and inviscid and that the flow approaches a uniform shear flow downstream. Exact relations are derived using conservation of mass and momentum for the case where the downstream free surface is flat. The complete nonlinear problem is solved numerically using a boundary integral method and these waveless solutions are shown to exist only when the height of the plate above the bottom is greater than the height of the uniform shear flow. Interesting results are found for various values of the constant vorticity. Solutions with downstream surface waves are also considered, and nonlinear results of this type are compared with linear results found previously. These solutions can be used to model the flow near the stern of a (two-dimensional) ship
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Hypomorphic PCNA mutation underlies a novel human DNA repair disorder
A number of human disorders, including Cockayne syndrome, UV-sensitive syndrome, xeroderma pigmentosum and trichothiodystrophy, result from the mutation of genes encoding molecules important for nucleotide excision repair. Here, we describe a novel syndrome in which the cardinal clinical features include postnatal growth retardation, hearing loss, premature aging, telangiectasia, neurological signs and photosensitivity, resulting from a homozygous missense (p.Ser228Ile) sequence alteration of the proliferating cell nuclear antigen (PCNA). PCNA is a highly conserved sliding clamp protein essential for DNA replication and repair. Due to this fundamental role, mutations in PCNA that profoundly impair protein function would be incompatible with life. Interestingly, while the p.Ser228Ile alteration appears to have no effect on protein levels or DNA replication, patient cells exhibit significant abnormalities in response to UV irradiation displaying substantial reductions in both UV survival and RNA synthesis recovery. The p.Ser228Ile change also profoundly alters PCNAâs interaction with Flap endonuclease 1 and DNA Ligase 1, DNA metabolism enzymes. Taken together our findings detail the first mutation of PCNA in humans, associated with a unique neurodegenerative disease displaying clinical and molecular features common to other DNA repair disorders, which we show to be attributable to a hypomorphic amino acid alteration
The Role of the Alternative Oxidase in Stabilizing the in Vivo Reduction State of the Ubiquinone Pool and the Activation State of the Alternative Oxidase
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