987 resultados para Moore, Josh
Resumo:
A new, and very simple spectrometer based on birefringent fiber is described. A resolution of 0.02 angstrom has been achieved, and the system has been used to measure diode laser chirp. A length of 10km of fiber would be sufficient to resolve single mode line widths.
Resumo:
本文综合形态学、孢粉学和细胞学以及等位酶分析的实验证据,阐明了中国华中铁角蕨复合体(Asplenium sarelii Hook. Complex)中两个四倍体种的起源问题,并从生物系统学的角度讨论了其中多个种的分类学问题。过去认为的四倍体的“华中铁角蕨”被证明是起源于二倍体华中铁角蕨(A. sarelii Hook.)和二倍体细茎铁角蕨(A. tenuicaule Hayata)的杂交,并被处理为新种:武当铁角蕨(A. wudangense Z.R. Wang et X. Hou, sp. nov.)。 而变异铁角蕨(A. varians Wall., Hook. et Grev.)则被认为起源于二倍体细茎铁角蕨(A. tenuicaule Hayata)和二倍体尖齿铁角蕨(A. argutum Ching)的杂交或二者同源四倍体的杂交。根据原细茎铁角蕨(A. tenuicaule Hayata)和尖齿铁角蕨(A. argutum Ching)在宏观和微观特征上的相似性,以及二者的遗传一致度(0.581~0.705),本文将这两个种处理为细茎铁角蕨(A. tenuicaule Hayata)的两个亚种:细茎亚种(ssp. tenuicaule)和尖齿亚种(ssp. argutum (Ching) Vaine, Rashbach et Reichst., ined.)。依据形态和遗传上的相似性以及各自占有一定部分重叠的分布区域,原云南铁角蕨(A. yunnanense Franch.)、宝兴铁角蕨(A. moupinense Franch.)和云南铁角蕨深裂铁角蕨变种(A. yunnanense Franch. var daraeiforme(Franch.)H. S. Kung)被处理为云南铁角蕨(A. yunnanense Franch.)的三个亚种:云南铁角蕨亚种(ssp. yunnanense)、宝兴铁角蕨亚种(ssp. moupinense (Franch.)Z. R. Wang et X. Hou, st. nov.)和深裂铁角蕨亚种(ssp. daraeiforme(Franch.)Z. R. Wang et X. Hou, st. nov.)。 同时,本文运用孢粉学、细胞学、生态学和形态学的综合手段,处理了中国铁角蕨(Asplenium trichomanes L. s. l.)的种下分类问题,划分了中国该种的四个亚种:原亚种A. trichomanes L. ssp. trichomanes,喜钙亚种A. trichomanes L. ssp. inexpectans Lovis,四倍亚种A. trichomanes L. ssp. quadrivalens D. E. Meyer emend. Lovis,粗轴亚种A. trichomanes L. ssp. pachyrachis (Christ) Lovis et Reichst.,并将一个变种:哈如变种A. trichomanes L. var. harovii Moore emend. Midle,归并入粗轴亚种ssp. pachyrahcis (Christ) Lovis et Reichst.,同时提供了它们在中国的分布情况。查阅研究PE的标本时发现一些定名为为A. trichomanes L. var. centrochinense Christ(中国变种)的模式标本碎片,因在形态上和倍性上均不同于已知分类群,认为应给予种的分类地位。
Resumo:
We discuss some fundamental characteristics of a phase-modulating device suitable to holographically project a monochrome video frame with 1280 x 720 resolution. The phase-modulating device is expected to be a liquid crystal over silicon chip with silicon area similar to that of commercial devices. Its basic characteristics, such as number of pixels, bits per pixel, and pixel dimensions, are optimized in terms of image quality and optical efficiency. Estimates of the image quality are made from the noise levels and contrast, while efficiency is calculated by considering the beam apodization, device dead space, diffraction losses, and the sinc envelope.
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The adjacency of 2 marine biogeographic regions off Cape Hatteras, North Carolina (NC), and the proximity of the Gulf Stream result in a high biodiversity of species from northern and southern provinces and from coastal and pelagic habitats. We examined spatiotemporal patterns of marine mammal strandings and evidence of human interaction for these strandings along NC shorelines and evaluated whether the spatiotemporal patterns and species diversity of the stranded animals reflected published records of populations in NC waters. During the period of 1997–2008, 1847 stranded animals were documented from 1777 reported events. These animals represented 9 families and 34 species that ranged from tropical delphinids to pagophilic seals. This biodiversity is higher than levels observed in other regions. Most strandings were of coastal bottlenose dolphins (Tursiops truncatus) (56%), harbor porpoises (Phocoena phocoena) (14%), and harbor seals (Phoca vitulina) (4%). Overall, strandings of northern species peaked in spring. Bottlenose dolphin strandings peaked in spring and fall. Almost half of the strandings, including southern delphinids, occurred north of Cape Hatteras, on only 30% of NC’s coastline. Most stranded animals that were positive for human interaction showed evidence of having been entangled in fishing gear, particularly bottlenose dolphins, harbor porpoises, short-finned pilot whales (Globicephala macrorhynchus), harbor seals, and humpback whales (Megaptera novaeangliae). Spatiotemporal patterns of bottlenose dolphin strandings were similar to ocean gillnet fishing effort. Biodiversity of the animals stranded on the beaches reflected biodiversity in the waters off NC, albeit not always proportional to the relative abundance of species (e.g., Kogia species). Changes in the spatiotemporal patterns of strandings can serve as indicators of underlying changes due to anthropogenic or naturally occurring events in the source populations.
Resumo:
A review of the significant contributions in the peer-reviewed literature indicates that the discarding of marine fish known as bycatch remains one of the most significant problem facing fisheries managers. Bycatch has negative affects on marine biodiversity, is ripe with ethical and moral issues surrounding the waste of life from increased juvenile fish mortality, hinders commercial profitability and recreational satisfaction, increases management costs, and results in socio-cultural problems and conflicts. While appearing to have a simple conservation engineering solution, reducing or eliminating bycatch in marine fishing operations given the presently existing regulated open access management environment is demonstrated to actually be so complex that its effects can appear to be counter-intuitive. An ecosystem simulation model that explicitly incorporates the human and biological dimensions is used to evaluate proposed bycatch reduction regulations for two fishing fleets exploiting three out of seven species of fish, each with ten cohorts, in two resource areas. One of the fishing fleets is divided into two components representing commercial fishermen and recreational anglers. The seven fish species represent predator, prey, and competitor behaviors and one stock is treated as an endangered species. The results displayed in a series of figures demonstrate the potential unintended effects of simplistic management approaches and the need for a holistic and comprehensive approach to bycatch management. That is, an ecosystem model that explicitly incorporates socio-cultural and biophysical attributes into a common framework allows the magnitude and direction of behavioral responses to be predicted based on changes in governance or biophysical constraints to determine if management goals and objectives have been obtained through the use of quantitative metrics.
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The imminent inability of silicon-based memory devices to satisfy Moore's Law is approaching rapidly. Controllable nanodomains of ferroic systems are anticipated to enable future high-density nonvolatile memory and novel electronic devices. We find via piezoresponse force microscopy (PFM) studies on lead zirconate titanate (PZT) films an unexpected nanostructuring of ferroelectric-ferroelastic domains. These consist of c-nanodomains within a-nanodomains in proximity to a-nanodomains within c-domains. These structures are created and annihilated as pairs, controllably. We treat these as a new kind of vertex-antivertex pair and consider them in terms of the Srolovitz-Scott 4-state Potts model, which results in pairwise domain vertex instabilities that resemble the vortex-antivortex mechanism in ferromagnetism, as well as dislocation pairs (or disclination pairs) that are well-known in nematic liquid crystals. Finally, we show that these nanopairs can be scaled up to form arrays that are engineered at will, paving the way toward facilitating them to real technologies.