Borrowing Constraints and the Tenure Choice of Young Households

In this paper we analyze the factors that affect the tenure choice of young adults, highlighting the impact of mortgage lender imposed borrowing constraints. The data set is a panel of youth age 20-33 for the years 1985-90. Our methods differ from most prior studies in many ways including consideration of possible sample selection bias, a richer model of the stochastic error structure, better measurement of which households are bound by borrowing constraints, and a fuller consideration of the endogeneity of wealth and income. Once all changes are implemented, we find ownership tendencies to be quite sensitive to economic variables. Specifically, potential earnings, the relative cost of owning a home, and especially borrowing constraints affect the tendency to own a home. In our sample of youth, 37% of households are constrained even after choosing their loan-to-value ratio to minimize the impact of the separate wealth and income requirements. The constraints reduce the probability of ownership of these households by 10 to 20 percentage points (a third to a half) depending on the particular characteristics of the household.

Expected Home Ownership and Real Wealth Accumulation of Youth

This paper describes the real wealth accumulation of American youth and relates this behavior to variations in real constant-quality house prices in their localities of residence. We argue that increases in the real constant-quality house price have two offsetting effects on wealth. First, the greater the local constant-quality price of housing, the greater the wealth needed to meet the lender imposed down payment constraint if housing demand is price inelastic. However, increased real constant-quality house price reduces the likelihood of home ownership and thus the desire the accumulate wealth needed for a down payment. Using a panel data set for youth age 20-33 for the years 1985 through 1990 we find that the combined direct and indirect impact of variations in real constant-quality house price on wealth is modest for changes near the average real house price, but youths' wealth declines substantially in areas with high real house price.

Microrheological Characterisation of Anisotropic Materials

We describe the measurement of anisotropic viscoelastic moduli in complex soft materials, such as biopolymer gels, via video particle tracking microrheology of colloid tracer particles. The use of a correlation tensor to find the axes of maximum anisotropy, and hence the mechanical director, is described. The moduli of an aligned DNA gel are reported, as a test of the technique; this may have implications for high DNA concentrations in vivo. We also discuss the errors in microrheological measurement, and describe the use of frequency space filtering to improve displacement resolution, and hence probe these typically high modulus materials.Comment: 5 pages, 5 figures. Replaced after refereeing/ improvement. Main results are the same. The final, published version of the paper is here http://link.aps.org/abstract/PRE/v73/e03190

Operator monotones, the reduction criterion and the relative entropy

We introduce the theory of operator monotone functions and employ it to derive a new inequality relating the quantum relative entropy and the quantum conditional entropy. We present applications of this new inequality and in particular we prove a new lower bound on the relative entropy of entanglement and other properties of entanglement measures.Comment: Final version accepted for publication, added references in reference [1] and [13

A unifying explanation of complex frequency spectra of gamma Dor, SPB and Be stars: combination frequencies and highly non-sinusoidal light curves

There are many Slowly Pulsating B (SPB) stars and γ Dor stars in the Kepler mission data set. The light curves of these pulsating stars have been classified phenomenologically into stars with symmetric light curves and with asymmetric light curves. In the same effective temperature ranges as the γ Dor and SPB stars, there are variable stars with downward light curves that have been conjectured to be caused by spots. Among these phenomenological classes of stars, some show ‘frequency groups’ in their amplitude spectra that have not previously been understood. While it has been recognized that non-linear pulsation gives rise to combination frequencies in a Fourier description of the light curves of these stars, such combination frequencies have been considered to be a only a minor constituent of the amplitude spectra. In this paper, we unify the Fourier description of the light curves of these groups of stars, showing that many of them can be understood in terms of only a few base frequencies, which we attribute to g-mode pulsations, and combination frequencies, where sometimes a very large number of combination frequencies dominate the amplitude spectra. The frequency groups seen in these stars are thus tremendously simplified. We show observationally that the combination frequencies can have amplitudes greater than the base frequency amplitudes, and we show theoretically how this arises. Thus for some γ Dor and SPB stars, combination frequencies can have the highest observed amplitudes. Among the B stars are pulsating Be stars that show emission lines in their spectra from occasional ejection of material into a circumstellar disc. Our analysis gives strong support to the understanding of these pulsating Be stars as rapidly rotating SPB stars, explained entirely by g-mode pulsations

Detections of massive stars in the cluster MCM2005b77, in the star-forming regions GRS G331.34−-00.36 (S62) and GRS G337.92−-00.48 (S36)

Large infrared and millimeter wavelength surveys of the Galactic plane have unveiled more than 600 new bubble HII regions and more than 3000 candidate star clusters. We present a study of the candidate clusters MCM2005b72, DBS2003-157, DBS2003-172, and MCM2005b77, based on near-infrared spectroscopy taken with SofI on the NTT and infrared photometry from the 2MASS, VVV, and GLIMPSE surveys. We find that (1) MCM2005b72 and DBS2003-157 are subregions of the same star-forming region, HII GRS G331.34-00.36 (bubble S62). MCM2005b72 coincides with the central part of this HII region, while DBS2003-157 is a bright mid-infrared knot of the S62 shell. We detected two O-type stars at extinction \Aks=1.0-1.3 mag. Their spectrophotometric properties are consistent with the near-kinematic distance to GRS G331.34-00.36 of 3.9pm0.3 kpc. (2) DBS2003-172 coincides with a bright mid-infrared knot in the S36 shell (GRS G337.92-00.48), where we detected a pair of candidate He I stars embedded in a small cometary nebula. (3) The stellar cluster MCM2005b77 is rich in B-type stars, has an average Aks of 0.91 mag, and is adjacent to the HII region IRAS 16137-5025. The average spectrophotometric distance of $\sim 5.0$ kpc matches the near-kinematic distance to IRAS 16137-5025 of 5.2pm0.1 kpc.Comment: 22 pages, 11 Figures, ApJ accepte

Treadmill exercise within lower body negative pressure protects leg lean tissue mass and extensor strength and endurance during bed rest.

Leg muscle mass and strength are decreased during reduced activity and non-weight-bearing conditions such as bed rest (BR) and spaceflight. Supine treadmill exercise within lower body negative pressure (LBNPEX) provides full-body weight loading during BR and may prevent muscle deconditioning. We hypothesized that a 40-min interval exercise protocol performed against LBNPEX 6 days week(-1) would attenuate losses in leg lean mass (LLM), strength, and endurance during 6° head-down tilt BR, with similar benefits for men and women. Fifteen pairs of healthy monozygous twins (8 male and 7 female pairs) completed 30 days of BR with one sibling of each twin pair assigned randomly as the non-exercise control (CON) and the other twin as the exercise subject (EX). Before and after BR, LLM and isokinetic leg strength and endurance were measured. Mean knee and ankle extensor and flexor strength and endurance and LLM decreased from pre- to post-BR in the male CON subjects (P < 0.01), but knee extensor strength and endurance, ankle extensor strength, and LLM were maintained in the male EX subjects. In contrast, no pre- to post-BR changes were significant in the female subjects, either CON or EX, likely due to their lower pre-BR values. Importantly, the LBNPEX countermeasure prevents or attenuates declines in LLM as well as extensor leg strength and endurance. Individuals who are stronger, have higher levels of muscular endurance, and/or have greater LLM are likely to experience greater losses during BR than those who are less fit

Intercomparison of standard resolution and high resolution TOVS soundings with radiosonde, lidar, and surface temperature/humidity data

One objective of the FIRE Cirrus IFO is to characterize relationships between cloud properties inferred from satellite observations at various scales to those obtained directly or inferred from very high resolution measurements. Satellite derived NOAA-9 high and standard resolution Tiros Operational Vertical Sounder (TOVS) soundings are compared with directly measured lidar, surface temperature, humidity, and vertical radiosonde profiles associated with the Ft. McCoy site. The results of this intercomparison should be useful in planning future cloud experiments