7,306 research outputs found
Do Housing Submarkets Really Matter?
We maintain that the appropriate definition of submarkets depends on the use to which they will be put. For mass appraisal purposes, submarkets should be defined so that the accuracy of hedonic predictions will be optimized. Thus we test whether out-of-sample hedonic value predictions can be improved when a large urban housing market is divided into submarkets and we explore the effects of alternative definitions of submarkets on the accuracy of predictions. We compare a set of submarkets based on small geographical areas defined by real estate appraisers with a set of statistically generated submarkets consisting of dwellings that are similar but not necessarily contiguous. The empirical analysis uses a transactions database from Auckland, New Zealand. Price predictions are found to be most accurate when based on the housing market segmentation used by appraisers. We conclude that housing submarkets matter, and location plays the major role in explaining why they matter.Housing; Submarkets; Price Predictions; Mass Appraisal; Hedonic Method
Sub-Poissonian statistics of Rydberg-interacting dark-state polaritons
Interfacing light and matter at the quantum level is at the heart of modern
atomic and optical physics and enables new quantum technologies involving the
manipulation of single photons and atoms. A prototypical atom-light interface
is electromagnetically induced transparency, in which quantum interference
gives rise to hybrid states of photons and atoms called dark-state polaritons.
We have observed individual dark-state polaritons as they propagate through an
ultracold atomic gas involving Rydberg states. Strong long-range interactions
between Rydberg atoms give rise to an effective interaction blockade for
dark-state polaritons, which results in large optical nonlinearities and
modified polariton number statistics. The observed statistical fluctuations
drop well below the quantum noise limit indicating that photon correlations
modified by the strong interactions have a significant back-action on the
Rydberg atom statistics.Comment: 7 pages, 4 figure
How HIV-1 Takes Advantage of the Cytoskeleton during Replication and Cell-to-Cell Transmission
Human immunodeficiency virus 1 (HIV-1) infects T cells, macrophages and dendritic cells and can manipulate their cytoskeleton structures at multiple steps during its replication cycle. Based on pharmacological and genetic targeting of cytoskeleton modulators, new imaging approaches and primary cell culture models, important roles for actin and microtubules during entry and cell-to-cell transfer have been established. Virological synapses and actin-containing membrane extensions can mediate HIV-1 transfer from dendritic cells or macrophage cells to T cells and between T cells. We will review the role of the cytoskeleton in HIV-1 entry, cellular trafficking and cell-to-cell transfer between primary cells
Cosmological Inflation and the Quantum Measurement Problem
According to cosmological inflation, the inhomogeneities in our universe are
of quantum mechanical origin. This scenario is phenomenologically very
appealing as it solves the puzzles of the standard hot big bang model and
naturally explains why the spectrum of cosmological perturbations is almost
scale invariant. It is also an ideal playground to discuss deep questions among
which is the quantum measurement problem in a cosmological context. Although
the large squeezing of the quantum state of the perturbations and the
phenomenon of decoherence explain many aspects of the quantum to classical
transition, it remains to understand how a specific outcome can be produced in
the early universe, in the absence of any observer. The Continuous Spontaneous
Localization (CSL) approach to quantum mechanics attempts to solve the quantum
measurement question in a general context. In this framework, the wavefunction
collapse is caused by adding new non linear and stochastic terms to the
Schroedinger equation. In this paper, we apply this theory to inflation, which
amounts to solving the CSL parametric oscillator case. We choose the
wavefunction collapse to occur on an eigenstate of the Mukhanov-Sasaki variable
and discuss the corresponding modified Schroedinger equation. Then, we compute
the power spectrum of the perturbations and show that it acquires a universal
shape with two branches, one which remains scale invariant and one with nS=4, a
spectral index in obvious contradiction with the Cosmic Microwave Background
(CMB) anisotropy observations. The requirement that the non-scale invariant
part be outside the observational window puts stringent constraints on the
parameter controlling the deviations from ordinary quantum mechanics...
(Abridged).Comment: References added, minor corrections, conclusions unchange
Imaging of non-operated cholesteatoma: Clinical practice guidelines
SummaryMiddle ear cholesteatoma is an aggressive form of chronic otitis media requiring surgical therapy. The surgical strategy depends on the location of the lesion, its extensions to the middle ear and mastoid, the anatomical conformation of the tympanomastoid cavities and the health status of the patient (as well as his or her interest in aquatic leisure activities). For several years, imaging of the ear has been a routine test in the preoperative work-up of the disease. National guidelines for the topic “Imaging of non-operated middle ear cholesteatoma” were prepared in October 2010, for the annual congress of the French Society of Otolaryngology Head and Neck Surgery (SFORL), by a panel of experts from the SFORL, represented by the French Association of Otology and Neuro-otology (AFON), and the French Radiological Society (SFR), represented by the French Society of Head and Neck Imaging (CIREOL). These guidelines are presented in the present article
Cross-Border Impact Assesment 2020:Implementation and possible effects of the Dutch Strategy on Spatial Planning and the Environment (NOVI) from a Euregional perspective
<br/
Association Between Supratotal Glioblastoma Resection and Patient Survival: A Systematic Review and Meta-Analysis
- BACKGROUND: Gross total resection (GTR) of the contrast enhancing (CE)
area will improve the survival of patients with glioblastoma (GBM). However,
GBM can infiltrate into the brain parenchyma, beyond the CE margins. It remains
unclear whether resection beyond the CE area (supratotal resection [SPTR]) can
improve survival without causing additional neurological deficits. The aim of the
present meta-analysis was to study the association between SPTR and overall
survival of patients of GBM.
- METHODS: Embase, PubMed, and other literature databases were searched
for eligible studies until August 2018. Studies involving patients with GBM that
had compared SPTR with GTR were included in the present study. The main
outcome was overall survival, presented as hazard ratios (HRs) with 95% confidence intervals (CIs) and median overall survival differences with the 95% CIs.
- RESULTS: The meta-analysis, which included 6 studies and 1168 unique patients with GBM, showed that compared with GTR, SPTR of GBM resulted in a
53% lower risk of mortality at any time during follow-up (HR, 0.47; 95% CI, 0.31e
0.72; P [ 0.0005). The median overall survival of the SPTR group was 6.4 months
(95% CI, 3.2e9.7) longer than the GTR group (P [ 0.0001). Reports on postoperative deficits were limited, and the quality of evidence was moderate to
very low.
- CONCLUSIONS: Compared with GTR, SPTR of GBM resulted in a lower risk of
mortality and longer median overall survival. However, the quality of evidence of
the available studies was poor. Therefore, it remains unclear whether SPTR is
safe and actually improves the survival of patients with GBM. Future prospective
trials and a standardized definition of SPTR are needed
Implications of solar wind measurements for solar models and composition
We critically examine recent claims of a high solar metallicity by von Steiger & Zurbuchen (2016, vSZ16) based on in situ measurements of the solar wind, rather than the standard spectroscopically inferred abundances (Asplund et al. 2009, hereafter AGSS09). We test the claim by Vagnozzi et al. (2016) that a composition based on the solar wind enables one to construct a standard solar model in agreement with helioseismological observations and thus solve the decades-old solar modelling problem. We show that, although some helioseismological observables are improved compared to models computed with spectroscopic abundances, most are in fact worse. The high abundance of refractory elements leads to an overproduction of neutrinos, with a predicted 8B flux that is nearly twice its observed value, and 7Be and CNO fluxes that are experimentally ruled out at high confidence. A combined likelihood analysis shows that models using the vSZ16 abundances are worse than AGSS09 despite a higher metallicity. We also present astrophysical and spectroscopic arguments showing the vSZ16 composition to be an implausible representation of the solar interior, identifying the first ionization potential effect in the outer solar atmosphere and wind as the likely culprit
- …