3,350 research outputs found
Real Estate Agent Remarks: Help or Hype?
This article groups the remarks of a multiple listing service listing into common themes and then uses a hedonic pricing model to determine whether such comments are priced in a meaningful way. The comments provide information on the motivation of the seller, location of the property and physical improvements or defects. Most of the comments analyzed are statistically significant. Negative comments are associated with lower sales prices suggesting the helpful nature of comments. Some of the positive comments, however, including "new paint" and "good location" are also associated with lower sales prices suggesting that some comments may be better classified as hype.
Nickel hydrogen low Earth orbit test program update and status
The current status of nickel-hydrogen (NiH2) testing ongong at NWSC, Crane In, and The Aerospace Corporation, El Segundo, Ca are described. The objective of this testing is to develop a database for NiH2 battery use in Low Earth Orbit (LEO) and support applications in Medium Altitude Orbit (MAO). Individual pressure vessel-type cells are being tested. A minimum of 200 cells (3.5 in diameter and 4.5 in diameter) are included in the test, from four U.S. vendors. As of this date (Nov. 18, 1986) approximately 60 cells have completed preliminary testing (acceptance, characterization, and environmental testing) and have gone into life cycling
Canonical Quantization Inside the Schwarzschild Black Hole
We propose a scheme for quantizing a scalar field over the Schwarzschild
manifold including the interior of the horizon. On the exterior, the timelike
Killing vector and on the horizon the isometry corresponding to restricted
Lorentz boosts can be used to enforce the spectral condition. For the interior
we appeal to the need for CPT invariance to construct an explicitly positive
definite operator which allows identification of positive and negative
frequencies. This operator is the translation operator corresponding to the
inexorable propagation to smaller radii as expected from the classical metric.
We also propose an expression for the propagator in the interior and express it
as a mode sum.Comment: 8 pages, LaTex. Title altered. One reference added. A few typos esp.
eq.(7),(38) corrected. To appear in Class.Q.Gra
Polymer state approximations of Schroedinger wave functions
It is shown how states of a quantum mechanical particle in the Schroedinger
representation can be approximated by states in the so-called polymer
representation. The result may shed some light on the semiclassical limit of
loop quantum gravity.Comment: 11 pages, 1 figure, Conclusions section adde
Quantitative genetics of learning ability and resistance to stress in Drosophila melanogaster.
Even though laboratory evolution experiments have demonstrated genetic variation for learning ability, we know little about the underlying genetic architecture and genetic relationships with other ecologically relevant traits. With a full diallel cross among twelve inbred lines of Drosophila melanogaster originating from a natural population (0.75 < F < 0.93), we investigated the genetic architecture of olfactory learning ability and compared it to that for another behavioral trait (unconditional preference for odors), as well as three traits quantifying the ability to deal with environmental challenges: egg-to-adult survival and developmental rate on a low-quality food, and resistance to a bacterial pathogen. Substantial additive genetic variation was detected for each trait, highlighting their potential to evolve. Genetic effects contributed more than nongenetic parental effects to variation in traits measured at the adult stage: learning, odorant perception, and resistance to infection. In contrast, the two traits quantifying larval tolerance to low-quality food were more strongly affected by parental effects. We found no evidence for genetic correlations between traits, suggesting that these traits could evolve at least to some degree independently of one another. Finally, inbreeding adversely affected all traits
Mass Superselection, Canonical Gauge Transformations, and Asymptotically Flat Variational Principles
The phase space reduction of Schwarzschild black holes by Thiemann and
Kastrup and by Kucha\v{r} is reexamined from a different perspective on gauge
freedom. This perspective introduces additional gauge transformations which
correspond to asymptotically nontrivial diffeomorphisms. Various subtleties
concerning variational principles for asymptotically flat systems are addressed
which allow us to avoid the usual conclusion that treating such transformations
as gauge implies the vanishing of corresponding total charges. Instead,
superselection rules are found for the (nonvanishing) ADM mass at the
asymptotic boundaries. The addition of phenomenological clocks at each
asymptotic boundary is also studied and compared with the `parametrization
clocks' of Kucha\v{r}.Comment: 15 pages, ReVTeX, Minor changes made in response to referee's
commment
Correlations of observables in chaotic states of macroscopic quantum systems
We study correlations of observables in energy eigenstates of chaotic systems
of a large size . We show that the bipartite entanglement of two subsystems
is quite strong, whereas macroscopic entanglement of the total system is
absent. It is also found that correlations, either quantum or classical, among
less than points are quite small. These results imply that chaotic states
are stable. Invariance of these properties under local operations is also
shown.Comment: 5 pages, 2 figure
Pion-Nucleon Scattering in Kadyshevsky Formalism: I Meson Exchange Sector
In a series of two papers we present the theoretical results of /meson-baryon scattering in the Kadyshevsky formalism. In this paper the
results are given for meson exchange diagrams. On the formal side we show, by
means of an example, how general couplings, i.e. couplings containing multiple
derivatives and/or higher spin fields, should be treated. We do this by
introducing and applying the Takahashi-Umezawa and the Gross-Jackiw method. For
practical purposes we introduce the method. We also show how the
Takashashi-Umezawa method can be derived using the theory of Bogoliubov and
collaborators and the Gross-Jackiw method is also used to study the
-dependence of the Kadyshevsky integral equation. Last but not least we
present the second quantization procedure of the quasi particle in Kadyshevsky
formalism.Comment: 29 page
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