The black-white test score gap widens with age?

We re-examine the theoretical concept of a production function for cognitive achievement, and argue that an indirect production function that depends upon the variables that constrain parents' choices is both moretractable from an econometric point of view, and more interesting from an economic point of view than is a direct production function that depends upon a detailed list of direct inputs such as number of books in the household. We estimate flexible econometric models of indirect production functions for two achievement measures from the Woodcock-Johnson Revised battery, using data from two waves of the Child Development Supplement to the PSID. Elasticities of achievement measures with respect to family income and parents' educational levels are positive and significant. Gaps between scores of black and white children narrow or remain constant as children grow older, a result that differs from previous findings in the literature. The elasticities of achievement scores with respect to family income are substantially higher for children of black families, and there are some notable difference in elasticities with respect to parents' educational levels across blacks and whites.

Black Yield

Combined media on paper. 40" x 90"

Black Planes

Combined media on photographic paper. 88" x 40"

Black Reach

Combined media on photographic paper. 108½" x 55" City Club, Los Angeles

Black Wave

Combined media on photographic paper. 110" x 54" Los Angeles County Museum of Art (LACMA)

A new sand fly in the subgenus Nyssomyia (Diptera, psychodidae) from the Amazon basin of Brazil

Lutzomyia (Nyssomyia) waltoni m.sp., uma nova espécie de flebótomo é descrita e ilustrada. Observações ecológicas disponíveis são apresentadas. (AU)

Psychodopygus Leonidasdeanei a new species of sand fly (Diptera: Psychodidae) from Pará State, Brazil

The male and female of Psychodopygus leonidasdeanei n.sp., (Diptera : Psychodidae) are described and illustrated from specimens collected in Shannon traps near Santarém, Pará State, Brazil. This species is a member of the squamiventris series and information is given on the distribution of the members of this series in Pará. A pictorial guide to separate the males and some females from others in the series is given.

Female plumage spottiness and parasite resistance in the barn owl (Tyto alba)

The hypothesis that extravagant ornaments signal parasite resistance has received support in several species for ornamented males but more rarely for ornamented females. However, recent theories have proposed that females should often be under sexual selection, and therefore females may signal the heritable capacity to resist parasites. We investigated this hypothesis in the socially monogamous barn owl, Tyto alba, in which females exhibit on average more and larger black spots on the plumage than males, and in which males were suggested to choose a mate with respect to female plumage spottiness. We hypothesized that the proportion of the plumage surface covered by black spots signals parasite resistance. In line with this hypothesis, we found that the ectoparasitic fly, Carnus hemapterus, was less abundant on young raised by more heavily spotted females and those flies were less fecund. In an experiment, where entire clutches were cross-fostered between nests, we found that the fecundity of the flies collected on nestlings was negatively correlated with the genetic mother's plumage spottiness. These results suggest that the ability to resist parasites covaries with the extent of female plumage spottiness. Among females collected dead along roads, those with a lot of black spots had a small bursa of Fabricius. Given that parasites bigger the development of this immune organ, this observation further suggests that more spotted females are usually less parasitized. The same analyses performed on male plumage spottiness all provided non-significant results. To our knowledge, this study is the first one showing that a heritable secondary sexual characteristics displayed by females reflects parasite resistance.

A female sand fly (Diptera: Psychodidae spinosipes (Floch & Abonnenc, 1943)

A description is given of a female sand fly (Diptera: Psychodidae - Phlebotominae) similar to Brunptomyia spinosipes (Floch & Abonnenc, 1943).

The Black Box of Business Dynamics

Research in business dynamics has been advancing rapidly in the last years but the translation of the new knowledge to industrial policy design is slow. One striking aspect in the policy area is that although research and analysis do not identify the existence of an specific optimal rate of business creation and business exit, governments everywhere have adopted business start-up support programs with the implicit principle that the more the better. The purpose of this article is to contribute to understand the implications of the available research for policy design. Economic analysis has identified firm heterogeneity as being the most salient characteristic of industrial dynamics, and so a better knowledge of the different types of entrepreneur, their behavior and their specific contribution to innovation and growth would enable us to see into the ‘black box’ of business dynamics and improve the design of appropriate public policies. The empirical analysis performed here shows that not all new business have the same impact on relevant economic variables, and that self-employment is of quite a different economic nature to that of firms with employees. It is argued that public programs should not promote indiscriminate entry but rather give priority to able entrants with survival capacities. Survival of entrants is positively related to their size at birth. Innovation and investment improve the likelihood of survival of new manufacturing start-ups. Investment in R&D increases the risk of failure in new firms, although it improves the competitiveness of incumbents.

Development of Eosinophilia in dogs intradermically inoculated with sand fly saliva and Leishmania (Leishmania) chagasi stationary-phase promastigotes

Salivary glad lysates of the sand fly Lutzomia longipalpis have been shown to enhance the infectivity of Leishmania in mice. As shown herein, the simultaneous inoculation of Leishmania chagasi stationary-phase promastigotes and L. longipalpis salivary gland by the intradermal route in a group of mongrel dogs induced a statistically significant eosinophilia, in relation to dogs inoculated with Leishmania or with salivary gland lysate only. These dogs had no evidence of infection, in spite of the infectivity of the promastigotes when inoculated by the intravenous route.

Lutzomyia (Trichophoromyia) pastazaensis, a new species of phlebotomine sand fly (Diptera: Psychodidae: Phlebotominae) from the Peruvian Amazon

The phlebotomine sand fly Lutzomyia pastazaensis n. sp. is described and illustrated from specimens collected from the edge of primary forest near Andoas, Department of Loreto, Peru (03º00'S, 76º05'W). This species appears to belong to the subgenus Trichophoromyia Barreto 1962, whose members are generally restricted to the Amazon Basin.

Description of Lutzomyia (Evandromyia) sipani, a new species of Sand Fly (Diptera: Psychodidae) from Loreto Department, Peru

Lutzomyia sipani n.sp. is described from males collected in Loreto Department, Peru. The new species belongs to the subgenus Evandromyia mangabeira and confirms the presence of this group in Peru.

Description of a new species of sand fly Lutzomyia (Pressatia) mamedei n. sp. (Diptera: Psychodidae) from Rio de Janeiro, Brazil

A new species of sand fly from Santa Cruz, state of Rio de Janeiro, Brazil is described as Lutzomyia (Pressatia) mamedei.