On the Chow ring of Cynk-Hulek Calabi-Yau varieties and Schreieder varieties

This note is about certain locally complete families of Calabi-Yau varieties constructed by Cynk and Hulek, and certain varieties constructed by Schreieder. We prove that the cycle class map on the Chow ring of powers of these varieties admits a section, and that these varieties admit a multiplicative self-dual Chow-Kuenneth decomposition. As a consequence of both results, we prove that the subring of the Chow ring generated by divisors, Chern classes, and intersections of two cycles of positive codimension injects into cohomology, via the cycle class map. We also prove that the small diagonal of Schreieder surfaces admits a decomposition similar to that of K3 surfaces. As a by-product of our main result, we verify a conjecture of Voisin concerning zero-cycles on the self-product of Cynk-Hulek Calabi-Yau varieties, and in the odd-dimensional case we verify a conjecture of Voevodsky concerning smash-equivalence. Finally, in positive characteristic, we show that the supersingular Cynk-Hulek Calabi-Yau varieties provide examples of Calabi-Yau varieties with "degenerate" motive.Comment: to appear in the Canadian Journal of Mathematic

Social Security Shortfall Warrants Action Soon

Analyzes Social Security trustees' projections for funding shortfalls, including the sources and ranges of uncertainty and the long-term budgetary context. Outlines the advantages of taking legislative action early to address the gap

Preliminary Investigation on the Physiology and Ecology of Luminescence in the Copepod, Metridia lucens

1. Skin glands believed to be the source of luminescence were found on the anterior portion of the head, on the last thoracic segment, and on the posterior margins of each segment of the abdomen. 2. The maximum intensity of the luminescent flash was 1.2 x 10-3 µw./cm.2 (at 18 cm.). The flash rose rapidly to peak intensity and then decayed slowly. The total duration of the flashes with peaks greater than 10-4 µw./cm.2 ranged from 3 to 50 seconds. 3. The peak of the luminescence spectrum occcurred at 482 mµ and the curve fell off to one-half the maximum value at 440 mµ and 525 mµ. 4. The ability of Metridia to luminesce on stimulation was found to be largely unaffected by prolonged laboratory culture. Starvation had little effect on the luminescence for the first three weeks and there was never any inhibition by previous light- or dark-adaptation. 5. With an increase in the strength of the electric stimulus from 0.3 amp. to 0.7 amp., the intensity of the luminescent flash was found to increase. With pulses stronger than 0.7 amp. no change in intensity was recorded but the number of successive responses to repeated stimuli was reduced. Duration of the pulse had little effect on the intensity or the number of successive responses. 6. Metridia showed a lag time of 8-10 msc. to the beginning of the luminescent response. The lag time to the peak of the luminescent response varied from 20 to 60 msc. 7. There was no spontaneous luminescence produced by groups of Metridia under conditions of constant darkness. However, the presence of certain planktonic predators, most notably Meganyctiphanes norvegica, caused a brilliant display of luminescence. The number of flashes attributable to Metridia was always greater than the number of Metridia eaten by the predator. There was little evidence that the luminescent euphausiid, Meganyctiphanes, flashed spontaneously either in the presence or absence of its prey. 8. Observations on the behavior of Metridia during and just after luminescence suggest that the flashing may be involved in an escape mechanism, but the precise effect of the light on the predator has not been determined

Initiation of Olefin Metathesis: Reaction of Deca-2,8-diene with Catalysts formed from Me_4Sn-WC1_6 and Me_3Al_2Cl_3-(Ph_3P)_2(NO)_2Cl_2Mo

The initial product of the metathesis of deca-2,8-diene with metathesis catalysts formed from either Me_4Sn–WCl_6 or Me_3Al_2Cl_3–(Ph_3P)_2(NO)_2Cl_2Mo is propene; labelling of the terminal groups of the diene and the alkylating agents gives a labelling pattern in the propene that is best explained in terms of generation of a carbene in the initiation step from the alkylating agent

A synthesis of the role of media reports and elections in Nigerian democracy

This paper examines the interplay between the media and the elections in Nigeria, and discusses some of the relevant communication models that could assist the media in effectively reporting future elections in the country. This study has employed a historical approach, and argues that since Nigeria attained its political independence in 1960; conducting free and fair elections has been the major political problem in the country. The paper observed that the June 12 1993 Presidential Elections resulted in a stalemate, while the 2007 Elections were flawed with cases of electoral irregularities. Many of the results of the elections that were approved earlier by the Independent National Electoral Commission (INEC) were later cancelled by the Nigerian Judiciary, a confirmation that the elections were rigged as confirmed by most of the internal and the external observers that monitored the elections. As a part of the solutions to the problem of elections in Nigeria, this paper recommends the establishment of an Inter-Party Central Committee (ICPP), made up of the national executives of the registered political parties, to work in collaboration with the media as the committee supports the electoral commission to conduct free and fair elections in the country