The gradual “whitening” of Puerto Rico over the course of the twentieth century is often noted in scholarly, journalistic, and popular descriptions of the island’s population. In 1899, a year after Puerto Rico came under U.S. dominion, the census reported that 62 percent of the population was white; by the year 2000, according to official census results, the white proportion of the Puerto Rican...

General purpose technologies (GPTs) are credited with generating the increasing returns that drive endogenous growth. For example, Paul David (1991) explains the surge in U.S. productivity during the 1920’s as a delayed response to the introduction of the electric dynamo in the 1880’s. To the extent that GPTs yield large positive externalities on a wide range of industries some time after they ...

Die Teilung Schleswigs nach Volksabstimmungen im Jahre 1920 hatte langfristige Folgen nördlich und südlich der neuen Grenze. Viele wurden durch Agitation Abstimmung tief beeindruckt, sogar die Archive des Gebiets mussten geteilt werden. Nordschleswig wurde als ein Teil Königreichs Dänemarks einverleibt. Diese von einem nordschleswigschen Ministerium vorbereitet kam bei Konstruktion Grenze sowie...

BACKGROUND Molophilus Curtis, 1833 is the most species-rich Limoniidae genus with a total number of 1006 species and subspecies, from which 97 are recorded in the Western-Palaearctic region so far. However new species are still expected from less investigated regions, like the Balkans or the Eastern Europe. NEW INFORMATION In the present article, we desrcibe a new limonid crane fly species, M...

As is the case with all epochs, the present one has its own characteristics—both in its political and in its scientific aspects. The science of 1960 is not the science of 1920 ; and, most emphatically, the astronomy of 1960 is not the astronomy of 1920. The differences are not entirely differences in instrumentation and in techniques ; even if the instruments of the 1950’s had been identical wi...

9 S. J. Barnett, Physic. Rev., 25, 835, 1925. 10 This can, for instance, be seen from Darwin's Lagrangian and Hamiltonian functions for atoms in magnetic fields, Phil. Mag., 39, 537, 1920. 11 P. Tartakowsky, Zeits. f. Physik, 34, 216, 1925. 12 P. Debye, Physic. Rev., 25, 586A, 1925. 13 A. Pascal, numerous references listed in Jahr. d. Rad. and Elektr., 17, 184, 1920. 14 The value e = 1.0000693 ...

This article briefly reviews current knowledge about leishmaniasis in Ecuadorproceeding from 1920, when the first human case was described, to the present. Regarding basic conditions, it appears that 34 of Ecuador’s 20 provinces have endemic leishmaniasis. Nationally, over 4,000 cases were registered in the 19831986 period. Of 260 cases cited in the literature from 1920 through 1987, 240 (92.3%...

2 Sumner, F. B., and Huestis, R. R., Genetics, Sept., 1921. 3 Almost nothing has been done in the way of hybridizing subspecies. But after all subspecies do not differ in any essential way from species. Whether or not two groups of mammals or birds are regarded as species or subspecies depends upon whether the intergrading forms have been preserved. The extremes are often more widely distinct t...