8,843 research outputs found
Using Quantile Regression in Hedonic Analysis to Reveal Submarket Competition
A root concern of hedonic property value models is that some commonly-used estimators aggregate very diverse households into a single regression, which may explain the marked differences in implicit price estimates for the same housing attributes across studies. In this paper, we extend a model that captures household heterogeneity through submarket identification and use quantile regression analysis to explore the role submarket competition plays in setting housing prices in those price ranges where different submarkets occupy homes of similar price. We find evidence of direct competition between submarkets with different preferences for at least some homes in a single neighborhood market. We cluster packages of attributes into three broad indices: dwelling structure variables, location variables, and adjacency variables. In the price ranges of competition between two submarkets, there is a clear premium paid in one of the indexed attribute by the final occupant to ‘outbid’ a member from another submarket. The attributes that realize a premium are those that are expected from prior analysis on what those submarkets prefer; and these premiums introduce variation in housing prices that would not be captured by standard hedonic approaches. By examining hedonic parameter instability at different housing price levels, we uncover not only latent diversity among homeowners but direct competition between them that calls into question policy and market conclusions drawn from standard hedonic price models, especially large sample hedonic studies.
Free subgroups of one-relator relative presentations
Suppose that G is a nontrivial torsion-free group and w is a word over the
alphabet G\cup\{x_1^{\pm1},...,x_n^{\pm1}\}. It is proved that for n\ge2 the
group \~G= always contains a nonabelian free subgroup.
For n=1 the question about the existence of nonabelian free subgroups in \~G is
answered completely in the unimodular case (i.e., when the exponent sum of x_1
in w is one). Some generalisations of these results are discussed.Comment: V3: A small correction in the last phrase of the proof of Theorem 1.
4 page
The Kervaire-Laudenbach conjecture and presentations of simple groups
The statement ``no nonabelian simple group can be obtained from a nonsimple
group by adding one generator and one relator"
1) is equivalent to the Kervaire--Laudenbach conjecture;
2) becomes true under the additional assumption that the initial nonsimple
group is either finite or torsion-free.
Key words: Kervaire--Laudenbach conjecture, relative presentations, simple
groups, car motion, cocar comotion.
AMS MSC: 20E32, 20F05, 20F06.Comment: 20 pages, 13 figure
Carter-like constants of the motion in Newtonian gravity and electrodynamics
For a test body orbiting an axisymmetric body in Newtonian gravitational
theory with multipole moments Q_L, (and for a charge in a non-relativistic
orbit about a charge distribution with the same multipole moments) we show that
there exists, in addition to the energy and angular momentum component along
the symmetry axis, a conserved quantity analogous to the Carter constant of
Kerr spacetimes in general relativity, if the odd-L moments vanish, and the
even-L moments satisfy Q_2L = m (Q_2/m)^L. Strangely, this is precisely the
relation among mass moments enforced by the no-hair theorems of rotating black
holes. By contrast, if Newtonian gravity is supplemented by a multipolar
gravitomagnetic field, whose leading term represents frame-dragging (or if the
electrostatic field is supplemented by a multipolar magnetic field), we are
unable to find an analogous Carter-like constant. This further highlights the
very special nature of the Kerr geometry of general relativity.Comment: 4 page
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Distinct ligand binding sites in integrin alpha3beta1 regulate matrix adhesion and cell-cell contact.
The integrin alpha3beta1 mediates cellular adhesion to the matrix ligand laminin-5. A second integrin ligand, the urokinase receptor (uPAR), associates with alpha3beta1 via a surface loop within the alpha3 beta-propeller (residues 242-246) but outside the laminin binding region, suggesting that uPAR-integrin interactions could signal differently from matrix engagement. To explore this, alpha3-/- epithelial cells were reconstituted with wild-type (wt) alpha3 or alpha3 with Ala mutations within the uPAR-interacting loop (H245A or R244A). Wt or mutant-bearing cells showed comparable expression and adhesion to laminin-5. Cells expressing wt alpha3 and uPAR dissociated in culture, with increased Src activity, up-regulation of SLUG, and down-regulation of E-cadherin and gamma-catenin. Src kinase inhibition or expression of Src 1-251 restored the epithelial phenotype. The H245A and R244A mutants were unaffected by coexpression of uPAR. We conclude that alpha3beta1 regulates both cell-cell contact and matrix adhesion, but through distinct protein interaction sites within its beta-propeller. These studies reveal an integrin- and Src-dependent pathway for SLUG expression and mesenchymal transition
Oxygen Consumption of Adrenalectomized and Renal Damaged Frogs
Author Institution: Department of Physiology, College of Medicine, The Ohio State University, Columbus 1
A Terraced Scanning Superconducting Quantum Interference Device Susceptometer with Sub-Micron Pickup Loops
Superconducting Quantum Interference Devices (SQUIDs) can have excellent spin
sensitivity depending on their magnetic flux noise, pick-up loop diameter, and
distance from the sample. We report a family of scanning SQUID susceptometers
with terraced tips that position the pick-up loops 300 nm from the sample. The
600 nm - 2 um pickup loops, defined by focused ion beam, are integrated into a
12-layer optical lithography process allowing flux-locked feedback, in situ
background subtraction and optimized flux noise. These features enable a
sensitivity of ~70 electron spins per root Hertz at 4K.Comment: See http://stanford.edu/group/moler/publications.html for an
auxiliary document containing additional fabrication details and discussio
Infinite-dimensional Compact Quantum Semigroup
In this paper we construct a compact quantum semigroup structure on the
Toeplitz algebra . The existence of a subalgebra, isomorphic to
the algebra of regular Borel's measures on a circle with convolution product,
in the dual algebra is shown. The existence of Haar functionals
in the dual algebra and in the above-mentioned subalgebra is proved. Also we
show the connection between and the structure of weak Hopf
algebra.Comment: 17 page
Post-Newtonian gravitational radiation and equations of motion via direct integration of the relaxed Einstein equations. III. Radiation reaction for binary systems with spinning bodies
Using post-Newtonian equations of motion for fluid bodies that include
radiation-reaction terms at 2.5 and 3.5 post-Newtonian (PN) order (O[(v/c)^5]
and O[(v/c)^7] beyond Newtonian order), we derive the equations of motion for
binary systems with spinning bodies. In particular we determine the effects of
radiation-reaction coupled to spin-orbit effects on the two-body equations of
motion, and on the evolution of the spins. For a suitable definition of spin,
we reproduce the standard equations of motion and spin-precession at the first
post-Newtonian order. At 3.5PN order, we determine the spin-orbit induced
reaction effects on the orbital motion, but we find that radiation damping has
no effect on either the magnitude or the direction of the spins. Using the
equations of motion, we find that the loss of total energy and total angular
momentum induced by spin-orbit effects precisely balances the radiative flux of
those quantities calculated by Kidder et al. The equations of motion may be
useful for evolving inspiraling orbits of compact spinning binaries.Comment: 19 pages, small corrections, equivalent to published versio
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