Consideration of midocean fish production as related to oceanic circulatory systems

The sea receives most of the radiant energy reaching the earth simply because there is more sea than land, especially in middle and low latitudes where the angle of incidence is greatest and the loss by reflection is least…

Estimations of abundance of the eggs of the pacific pilchard (Sardinops caerulea) off southern California during 1940 and 1941

One of the more important items of information required for an understanding of the dynamics of population numbers in marine fish stocks is the rate of replenishment of the stock through its reproductive process. It has been established for the Pacific pilchard, or California sardine (Sardinops caerulea), that some spawning seasons give rise to much larger year-classes than others (Clark, 1939), as measured at the time the year-class reaches commercial age...

Evidence of anomalous dispersion of the generalized sound velocity in glasses

The dynamic structure factor, S(Q,w), of vitreous silica, has been measured by inelastic X-ray scattering in the exchanged wavevector (Q) region Q=4-16.5 nm-1 and up to energies hw=115 meV in the Stokes side. The unprecedented statistical accuracy in such an extended energy range allows to accurately determine the longitudinal current spectra, and the energies of the vibrational excitations. The simultaneous observation of two excitations in the acoustic region, and the persistence of propagating sound waves up to Q values comparable with the (pseudo-)Brillouin zone edge, allow to observe a positive dispersion in the generalized sound velocity that, around Q=5 nm-1, varies from 6500 to 9000 m/s: this phenomenon was never experimentally observed in a glass.Comment: 5 pages, 3 figures. To appear in Phys. Rev.

The impact of cerebral vasomotor reactivity on cerebrovascular diseases and cognitive impairment

The regulation of cerebral blood flow (CBF) is a complex and tightly controlled function ensuring delivery of oxygen and nutrients and removal of metabolic wastes from brain tissue. Cerebral vasoreactivity (CVR) refers to the ability of the nervous system to regulate CBF according to metabolic demands or changes in the microenvironment. This can be assessed through a variety of nuclear medicine and imaging techniques and protocols. Several studies have investigated the association of CVR with physiological and pathological conditions, with particular reference to the relationship with cognitive impairment and cerebrovascular disorders (CVD). A better understanding of the interaction between CVR and cognitive dysfunction in chronic and particularly acute CVD could help improving treatment and rehabilitation strategies in these patients. In this paper, we reviewed current knowledge on CVR alterations in the context of acute and chronic CVD and cognitive dysfunction. Alterations in CVR and hemodynamics have been described in patients with both neurodegenerative and vascular cognitive impairment, and the severity of these alterations seems to correlate with CVR derailment. Furthermore, an increased risk of cognitive impairment progression has been associated with alterations in CVR parameters and hemodynamics. Few studies have investigated these associations in acute cerebrovascular disorders and the results are inconsistent; thus, further research on this topic is encouraged

Interação morcego-fruto : estado da arte no Brasil e um estudo da chuva de sementes por aves e morcegos em uma área do Cerrado em Brasília

Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Biológicas, Programa de Pós-Graduação em Ecologia, 2012.A proposta da presente dissertação é contribuir para o avanço do conhecimento sobre o serviço de dispersão de sementes realizado por aves e morcegos. Por meio de uma revisão da literatura avaliei o estado da arte da interação morcego-fruto no Brasil, e por meio de uma pesquisa de campo comparei a chuva de sementes produzida por aves e morcegos em uma área do Cerrado em Brasília. Por meio da revisão da literatura obtive 64 publicações relacionadas à interação morcego-fruto no Brasil. Analisei a evolução histórica dessas pesquisas, os biomas onde já foram realizadas e os métodos nelas utilizados. Obtive uma listagem de 33 espécies de morcegos dispersores de sementes e 90 espécies de plantas dispersadas por morcegos no Brasil. Concluí que embora o número de publicações tenha aumentado a cada década, o conhecimento ainda é incipiente. Além disso, as pesquisas sobre a interação morcego-fruto estão concentradas no eixo sul-sudeste do Brasil, fornecendo poucos dados para outras regiões do país. Embora existam diferentes métodos sendo utilizados nas pesquisas, a coleta de amostras fecais e estomacais é o mais utilizado. Espero que a listagem de espécies de morcegos dispersores e plantas dispersadas por morcegos que foi aqui construída possa ser uma ferramenta útil a ser utilizada, por exemplo, em programas de restauração ecológica de áreas degradadas. No estudo de campo meu objetivo foi comparar a chuva de sementes produzida por aves e morcegos em uma área do Cerrado em Brasília. O estudo foi desenvolvido na Reserva Ecológica do IBGE, Brasília, DF. Utilizei 120 coletores de sementes, 60 em cada habitat (mata de galeria e cerrado típico), vistoriados ao amanhecer e ao entardecer durante cinco dias por mês, cinco meses em cada estação (seca e chuvosa). Fezes de aves e morcegos foram coletadas e triadas na busca por sementes, que depois de contadas e identificadas foram colocadas para germinar. Concluí que os morcegos são os principais dispersores de sementes na área do estudo, dispersando uma maior quantidade e variedade de sementes que as aves. A chuva de sementes produzida por aves e morcegos sofre variações influenciadas pelo habitat e pela estação. O sucesso germinativo das sementes dispersadas pelas aves é maior que as dispersadas pelos morcegos. Na área estudada, espécies de Miconia podem depender do serviço de dispersão de sementes realizado por aves, morcegos e marsupiais, e as espécies do gênero parecem estar sendo um recurso alimentar importante não só para aves como para os morcegos e marsupiais. _________________________________________________________________________________ ABSTRACTThe purpose of this dissertation is to contribute to the increase of knowledge about seed dispersal service carried by birds and bats. Through a review of the literature I assess the state of the art of bat-fruit interaction in Brazil, and through a field study I compare the seed rain produced by birds and bats in an area of Brazilian savanna. Through the literature review I gathered 64 publications related to bat-fruit interaction in Brazil. I reviewed the historical evolution of these surveys, the biomes which have already been made and the methods used in them. I got a list of 33 species of bats as seed dispersers and 90 plant species dispersed by bats in Brazil. I concluded that although the number of publications has increased in each decade, the knowledge is still incipient. Moreover, researches on bat-fruit interaction are concentrated in the southern and southeastern of Brazil, providing little data for other regions of the country. Although there are different methods being used in field working, collecting fecal and stomach samples is the most used. I hope the list of bat species and plants they disperse built here can be at least useful for example, in programs of vegetation restoration. In the field part of this dissertation the goal was to compare the seed rain produced by birds and bats in two phytophysiognomies of Cerrado (savanna) in Brasilia. The study was conducted at the Ecological Reserve of IBGE. A total of 120 seed traps, 60 in each habitat (gallery forest and savanna typical) were displayed and surveyed at dawn and dusk for five days per month, five months in each season (dry and wet). Feces of birds and bats were collected and screened in search of seeds, which were counted and identified after germinated. I concluded that bats are major seed dispersers in the study area, dispersing a greater quantity and variety of seeds than the birds. Seed rain produced by birds and bats suffer variations that are influenced by habitat and season. The success of germination of seeds dispersed by birds is higher than that dispersed by bats. In the study area, Miconia species may depend on the seed dispersal service carried by birds, bats, and marsupials. The species of the genus Miconia appear to be an important food resource for these animals

Enhanced electrocaloric efficiency via energy recovery.

Materials that show large and reversible electrically driven thermal changes near phase transitions have been proposed for cooling applications, but energy efficiency has barely been explored. Here we reveal that most of the work done to drive representative electrocaloric cycles does not pump heat and may therefore be recovered. Initially, we recover 75-80% of the work done each time BaTiO3-based multilayer capacitors drive electrocaloric effects in each other via an inductor (diodes prevent electrical resonance while heat flows after each charge transfer). For a prototype refrigerator with 24 such capacitors, recovering 65% of the work done to drive electrocaloric effects increases the coefficient of performance by a factor of 2.9. The coefficient of performance is subsequently increased by reducing the pumped heat and recovering more work. Our strategy mitigates the advantage held by magnetocaloric prototypes that exploit automatic energy recovery, and should be mandatory in future electrocaloric cooling devices

Crystal-like high frequency phonons in the amorphous phases of solid water

The high frequency dynamics of low- (LDA) and high-density amorphous-ice (HDA) and of cubic ice (I_c) has been measured by inelastic X-ray Scattering (IXS) in the 1-15 nm^{-1} momentum transfer (Q) range. Sharp phonon-like excitations are observed, and the longitudinal acoustic branch is identified up to Q = 8nm^{-1} in LDA and I_c and up to 5nm^{-1} in HDA. The narrow width of these excitations is in sharp contrast with the broad features observed in all amorphous systems studied so far. The "crystal-like" behavior of amorphous ices, therefore, implies a considerable reduction in the number of decay channels available to sound-like excitations which is assimilated to low local disorder.Comment: 4 pages, 3 figure