Homeowner Preferences after September 11th, a Microdata Approach

The existence of homeowner preferences - specifically homeowner preferences for neighbors -is fundamental to economic models of sorting. This paper investigates whether or not the terrorist attacks of September 11, 2001 (9/11) impacted local preferences for Arab neighbors. We test for changes in preferences using a differences-in-differences approach in a hedonic pricing model. Relative to sales before 9/11, we find properties within 0.1 miles of an Arab homeowner sold at a 1.4% discount in the 180 days after 9/11. The results are robust to a number of specifications including time horizon, event date, distance, time, alternative ethnic groups, and the presence of nearby mosques. Previous research has shown price effects at neighborhood levels but has not identified effects at the micro or individual property level, and for good reason: most transaction level data sets do not include ethnic identifiers. Applying methods from the machine learning and biostatistics literature, we develop a binomial classifier using a supervised learning algorithm and identify Arab homeowners based on the name of the buyer. We train the binomial classifier using names from Summer Olympic Rosters for 221 countries during the years 1948-2012. We demonstrate the flexibility of our methodology and perform an interesting counterfactual by identifying Hispanic and Asian homeowners in the data; unlike the statistically significant results for Arab homeowners, we find no meaningful results for Hispanic and Asian homeowners following 9/11

What is Near and Recent in Crime for a Homeowner? The Cases of Denver and Seattle

This paper analyzes the effects of the concentration of crime on housing prices using nonparametric methods. Specifically, we use a modified local K-function in order to measure crime concentration. This technique provides us with a crime measure that is not dependent on pre-defined boundaries. Results from this analysis suggest a decrease in housing prices of two percent to seven percent for crimes in the past six months that occur within a quarter of a mile of the house

Outflows From Evolved Stars: The Rapidly Changing Fingers Of CRL 618

Our ultimate goal is to probe the nature of the collimator of the outflows in the pre-planetary nebula CRL 618. CRL 618 is uniquely suited for this purpose owing to its multiple, bright, and carefully studied finger-shaped outflows east and west of its nucleus. We compare new Hubble Space Telescope images to images in the same filters observed as much as 11 yr ago to uncover large proper motions and surface brightness changes in its multiple finger-shaped outflows. The expansion age of the ensemble of fingers is close to 100 yr. We find strong brightness variations at the fingertips during the past decade. Deep IR images reveal a multiple ring-like structure of the surrounding medium into which the outflows propagate and interact. Tightly constrained three-dimensional hydrodynamic models link the properties of the fingers to their possible formation histories. We incorporate previously published complementary information to discern whether each of the fingers of CRL 618 are the results of steady, collimated outflows or a brief ejection event that launched a set of bullets about a century ago. Finally, we argue on various physical grounds that fingers of CRL 618 are likely to be the result of a spray of clumps ejected at the nucleus of CRL 618 since any mechanism that form a sustained set of unaligned jets is unprecedented.HST GO 11580NASA through Space Telescope Science Institute GO11580NASA NAS5-26555Boeing ScholarshipOffice of Undergraduate Academic Affairs at the University of WashingtonSpanish MICINN CSD2009-00038NASA Office of Space Science NAG5-7584Astronom

Coherence scanning interferometry for additive manufacture

Additive manufacture (AM) of metal components is a rapidly maturing technology; but given the large number of interrelated process parameters, it remains difficult to control to high precision. It has been observed that processing conditions may be associated with specific features in the surface texture [1], creating a drive to achieve fast, and reliable topographic measurement of metal AM surfaces. One of the most developed metal AM processes, selective laser melting (SLM), still produces parts that exhibit rough surface textures with dense distributions of features at a wide range of lateral and vertical scales, aspect ratios, and reflective properties; with the additional complication of the presence of high slopes, undercuts and surface recesses. These features make metal AM surfaces challenging to measure by both tactile and optical means [2,3]

Subject Islands are Different

Linguistic

Designing hollow nano gold golf balls.

Hollow/porous nanoparticles, including nanocarriers, nanoshells, and mesoporous materials have applications in catalysis, photonics, biosensing, and delivery of theranostic agents. Using a hierarchical template synthesis scheme, we have synthesized a nanocarrier mimicking a golf ball, consisting of (i) solid silica core with a pitted gold surface and (ii) a hollow/porous gold shell without silica. The template consisted of 100 nm polystyrene beads attached to a larger silica core. Selective gold plating of the core followed by removal of the polystyrene beads produced a golf ball-like nanostructure with 100 nm pits. Dissolution of the silica core produced a hollow/porous golf ball-like nanostructure

Identity Override: How Sexual Orientation Reduces the Rigidity of Racial Boundaries

Although most Americans have limited interpersonal relations with different-race others, interracial ties are notably more common among gay, lesbian, and bisexual (GLB) individuals. Departing from the modal explanation of intergroup relations theories, which suggests that individual propensities for between-group interactions are driven by demographic groups’ physical location relative to one another, we show that, beyond propinquity, GLB interraciality is spiked through active identification as GLB. We evaluate full romantic/sexual partnership histories along with friendship network racial compositions for respondents in a large, nationally representative sample. We show that GLBs have a greater likelihood and frequency than heterosexuals of forming multiple types of interracial ties and also that this effect applies only to those who actively identify as GLB and not to those who engage in same-sex relations but do not identify as GLB. This discovery refines theories of intergroup relations, isolating how identification serves as a mediating mechanism that can heighten the propensity for intergroup interaction. We argue that active identification with a group that crosses racial boundaries spurs overriding the rigidity of intergroup borders that otherwise dissuade interpersonal diversity