Varieties and the terms of trade

This paper analyzes the dynamic adjustment of the terms of trade in an intertemporal, two country model with endogenous product variety. In the base model, all workers are identical. In an extended version, the development of new varieties requires skilled labor while manufacturing uses skilled and unskilled labor. In the model without skill, a population increase in one of the countries has no effect on its terms of trade, not even in the short run. In the model with skill, the terms of trade initially worsen, but eventually return to their original level. The terms of trade immediately and permanently worsen in response to a productivity increase in manufacturing. However, they gradually improve if the productivity in variety research rises. If productivity in both activities rises equiproportionally, the terms of trade respond in the same manner as after a population shock.

Who Invests in Home Equity to Exempt Wealth from Bankruptcy?

Homestead exemptions to personal bankruptcy allow households to retain their home equity up to a limit determined at the state level. Households that may experience bankruptcy thus have an incentive to bias their portfolios towards home equity. Using US household data from the Survey of Income and Program Participation for the period 1996-2006, we find that especially households with low net worth maintain a larger share of their wealth as home equity if a larger homestead exemption applies. This home equity bias is also more pronounced if the household head is in poor health, increasing the chance of bankruptcy on account of unpaid medical bills. The bias is further stronger for households with mortgage finance, shorter house tenures, and younger household heads, which taken together reflect households that face more financial uncertainty.Homestead exemptions;Personal bankruptcy;Portfolio allocation;Home ownership

Role of Strigolactones in the Host Specificity of Broomrapes and Witchweeds

Root parasitic plants of the Orobanchaceae, broomrapes and witchweeds, pose a severe problem to agriculture in Europe, Asia and especially Africa. These parasites are totally dependent on their host for survival, and therefore, their germination is tightly regulated by host presence. Indeed, their seeds remain dormant in the soil until a host root is detected through compounds called germination stimulants. Strigolactones (SLs) are the most important class of germination stimulants. They play an important role in planta as a phytohormone and, upon exudation from the root, function in the recruitment of symbiotic arbuscular mycorrhizal fungi. Plants exude mixtures of various different SLs, possibly to evade detection by these parasites and still recruit symbionts. Vice versa, parasitic plants must only respond to the SL composition that is exuded by their host, or else risk germination in the presence of non-hosts. Therefore, parasitic plants have evolved an entire clade of SL receptors, called HTL/KAI2s, to perceive the SL cues. It has been demonstrated that these receptors each have a distinct sensitivity and specificity to the different known SLs, which possibly allows them to recognize the SL-blend characteristic of their host. In this review, we will discuss the molecular basis of SL sensitivity and specificity in these parasitic plants through HTL/KAI2s and review the evidence that these receptors contribute to host specificity of parasitic plants

Recreational cocaine polydrug use impairs cognitive flexibility but not working memory

Rationale: Chronic use of cocaine is associated with dysfunctions in frontal brain regions and dopamine D2 receptors, with poorer mental flexibility and a reduced ability to inhibit manual and attentional responses. Little is known, however, about cognitive impairments in the upcoming type of recreational cocaine polydrug user (1-4 g monthly consumption). Objective: We studied whether recreational cocaine polydrug users, who do not meet the criteria for abuse or dependence, showed impairments in working memory (WM) and cognitive flexibility. Methods: Controls and recreational cocaine polydrug users (who abstained from cocaine and other substances more than 1 week) were matched by sex, age, alcohol consumption, and IQ (Raven’s Standard Progressive Matrices). Groups were tested by using two cognitive tasks measuring cognitive flexibility and three tasks investigating the maintenance and monitoring of information in WM. Results: Recreational cocaine polydrug users performed significantly worse than controls on tasks tapping cognitive flexibility, but show comparable performance in the active maintenance and monitoring of information in WM. Conclusions: The findings suggest that recreational use of cocaine selectively impairs cognitive flexibility but not the maintenance of information in WM. The inability to adjust behavior rapidly and flexibly may have repercussions for daily life activities

Natural Selection and Morphological Variability: The Case of Europe From Neolithic to Modern Times [Comment]

https://www.journals.uchicago.edu/doi/abs/10.1086/20200

De grafemische buffer : aspecten van een spellingstoornis

Ce riche volume de 373 pages rassemble les contributions pour un colloque qui fut organisé les 30 novembre et 1 décembre 2012 par le “Centro Studi Sigismondo Castromediano e Gino Rizzo” à Cavallino di Lecce. Le personnage historique de premier plan qui fait l’objet du volume est Sigismondo Castromediano (Cavallino 1811-1895), surnommé le « Bianco Duca », noble de la région des Pouilles, arrêté en 1848 pour activité patriotique au sein de la Giovine Italia, condamné à trente ans de bagne, puis..

De grafemische buffer : aspecten van een spellingstoornis

A spelling disorder that received much attention recently is the so-called graphemic buffer impairment. Caramazza et al. (1987) presented the first systematic case study of a patient with this disorder. Miceli & Capasso (2006) provide an extensive overview of the relevant literature. This article adds to the literature by describing a Dutch case, i.e. patient BM. We demonstrate how specific features of Dutch and Dutch orthography interact with the graphemic buffer impairment. In addition, we paid special attention to the influence of grapheme position on the patient’s spelling accuracy. For this we used, in contrast with most of the previous literature, the proportional accountability method described in Machtynger & Shallice (2009). We show that by using this method the underlying error distribution can be more optimally captured than with classical methods. The result of this analysis replicates two distributions that have been previously reported in the literature. Finally, attention will be paid to the role of phonology in the described disorder

The Dependence of Galaxy Shape on Luminosity and Surface Brightness Profile

For a sample of 96,951 galaxies from the Sloan Digital Sky Survey Data Release 3, we study the distribution of apparent axis ratios as a function of r-band absolute magnitude and surface brightness profile type. We use the parameter fracDeV to quantify the profile type (fracDeV = 1 for a de Vaucouleurs profile; fracDeV = 0 for an exponential profile). When the apparent axis ratio q_{am} is estimated from the moments of the light distribution, the roundest galaxies are very bright (M_r \sim -23) de Vaucouleurs galaxies and the flattest are modestly bright (M_r \sim -18) exponential galaxies. When the apparent axis ratio q_{25} is estimated from the axis ratio of the 25 mag/arcsec^2 isophote, we find that de Vaucouleurs galaxies are flatter than exponential galaxies of the same absolute magnitude. For a given surface brightness profile type, very bright galaxies are rounder, on average, than fainter galaxies. We deconvolve the distributions of apparent axis ratios to find the distribution of the intrinsic short-to-long axis ratio gamma, assuming constant triaxiality T. For all profile types and luminosities, the distribution of apparent axis ratios is inconsistent with a population of oblate spheroids, but is usually consistent with a population of prolate spheroids. Bright galaxies with a de Vaucouleurs profile (M_r < -21.84, fracDeV > 0.9) have a distribution of q_{am} that is consistent with triaxiality in the range 0.4 < T < 0.8, with mean intrinsic axis ratio 0.66 < gamma < 0.69. The fainter de Vaucouleurs galaxies are best fit with prolate spheroids (T = 1) with mean axis ratio gamma = 0.51.Comment: 32 pages, 12 figures, to appear in Ap

The Ellipticity of the Disks of Spiral Galaxies

The disks of spiral galaxies are generally elliptical rather than circular. The distribution of ellipticities can be fit with a log-normal distribution. For a sample of 12,764 galaxies from the Sloan Digital Sky Survey Data Release 1 (SDSS DR1), the distribution of apparent axis ratios in the i band is best fit by a log-normal distribution of intrinsic ellipticities with ln epsilon = -1.85 +/- 0.89. For a sample of nearly face-on spiral galaxies, analyzed by Andersen and Bershady using both photometric and spectroscopic data, the best fitting distribution of ellipticities has ln epsilon = -2.29 +/- 1.04. Given the small size of the Andersen-Bershady sample, the two distribution are not necessarily inconsistent. If the ellipticity of the potential were equal to that of the light distribution of the SDSS DR1 galaxies, it would produce 1.0 magnitudes of scatter in the Tully-Fisher relation, greater than is observed. The Andersen-Bershady results, however, are consistent with a scatter as small as 0.25 magnitudes in the Tully-Fisher relation.Comment: 19 pages, 5 figures; ApJ, accepte

Information storage in piezoelectric powders

In this paper we show that a large amount of information can be stored in a sample of piezoelectric powders. The technique used to write and read the information is based on the principle of phonon echos. It is demonstrated that the frequency can serve as an address of a memory and that a word can be written into each address by selecting an appropriate writing pulse sequence. It is also shown that the information contained in one address can be read out quickly and nondestructively