989 research outputs found
Electron capture in GaAs quantum wells via electron-electron and optic phonon scattering
Electron capture times in a separate confinement quantum well (QW) structure
with finite electron density are calculated for electron-electron (e-e) and
electron-polar optic phonon (e-pop) scattering. We find that the capture time
oscillates as function of the QW width for both processes with the same period,
but with very different amplitudes. For an electron density of 10^11 cm^-2 the
e-e capture time is 10-1000 times larger than the e-pop capture time except for
QW widths near the resonance minima, where it is only 2-3 times larger. With
increasing electron density the e-e capture time decreases and near the
resonance becomes smaller than the e-pop capture time. Our e-e capture time
values are two-to-three orders of magnitude larger than previous results of
Blom et al. [Appl. Phys. Lett. 62, 1490 (1993)]. The role of the e-e capture in
QW lasers is therefore readdressed.Comment: 5 pages, standard LaTeX file + 5 PostScript figures (tarred,
compressed and uuencoded) or by request from [email protected],
accepted to Appl. Phys. Let
Alternativas na Colocação de Cateteres em Hemodiálise
Background: Although vascular access is essential for adequate haemodialysis delivery, the systematic use of a patient's venous patrimony may eventually lead to exhaustion of suitable sites for placement of
a new vascular access.
Case Report: We present two cases of such patients. In the first one we inserted a 55cm catheter through the left external iliac vein, and a 40cm translumbar catheter was placed in the second one. Both interventions
were performed percutaneously under radiological guidance. Both patients were anticoagulated after the procedure.
Conclusion: Unusual sites for haemodialysis catheter placement may be life saving in selected situations and offer safe and viable alternatives for adequate haemodialysis delivery
Farinha integral e raspa residual de mandioca na alimentação de frangos de corte.
bitstream/item/58593/1/CUsersPiazzonDocuments199.pd
Reação do capim-sudão (Sorghum sudanensis) Cv. brs estribo a Pratylechus brachiurus e Meloidogyne javanica. reaction of sudan grass (Sorghum sudanensis) Cv. BRS estribo to Pratylenchus brachyurus and Meloidogyne javanica.
Caracterização de especies do nematoide das lesões (Pratylenchus spp.) em batata na Região Sul do Brasil. characterization of lesion nematode (Pratylenchus spp.) species in potato crop in southern of Brazil.
Utilização do farelo de canola em rações para frangos de corte.
O que e farelo de canola?; O valor nutritivo do farelo de canola; Utilização do farelo de canola; Cuidados com o uso do farelo de canola.bitstream/item/59455/1/CUsersPiazzonDocuments4.pd
Global priorities for conservation across multiple dimensions of mammalian diversity
Conservation priorities that are based on species distribution, endemism, and vulnerability may underrepresent biologically unique species as well as their functional roles and evolutionary histories. To ensure that priorities are biologically comprehensive, multiple dimensions of diversity must be considered. Further, understanding how the different dimensions relate to one another spatially is important for conservation prioritization, but the relationship remains poorly understood. Here, we use spatial conservation planning to (i) identify and compare priority regions for global mammal conservation across three key dimensions of biodiversity-taxonomic, phylogenetic, and traits-and (ii) determine the overlap of these regions with the locations of threatened species and existing protected areas. We show that priority areas for mammal conservation exhibit low overlap across the three dimensions, highlighting the need for an integrative approach for biodiversity conservation. Additionally, currently protected areas poorly represent the three dimensions of mammalian biodiversity. We identify areas of high conservation priority among and across the dimensions that should receive special attention for expanding the global protected area network. These high-priority areas, combined with areas of high priority for other taxonomic groups and with social, economic, and political considerations, provide a biological foundation for future conservation planning efforts
- …