Electronic detection of weak spectrum links

Recording spectroscopic data by digital and analog electronic systems - Detection of weak spectrum line

Photoelectric Detection of Weak Spectrum Lines

Photoelectric detection of weak spectral lines by application of digital and gated filter electronic devices to optical spectrometr

Vispack

technical reportVISPACK (volume-image-surface package) is a C++ library that includes matrix, image, and volume objects and tools for manipulating level-set surface model

Isosurfaces and level-set surface models

technical reportThis paper is a set of notes that present the basic geometry of isosurfaces and the basic methods for using level sets to model deformable surfaces. It begins with a short introduction to isosurface geometry, including curvature. It continues with a short explanation of the level-set partial differential equations. It also presents some practical details for how to solve these equations using up-wind scheme and sparse calculation methods. This paper presents a series of examples of how level-set surface models are used to solve problems in graphics and vision. Finally, it presents some examples of implementations using VISPack, an object oriented, C++ library for doing volume processing and level-set surface modeling

Differential Gene Expression in the Anterior Forebrain Pathway Nucleus Area X During Rapid Vocal Learning

Vocal learning is the complex process by which an organism is able to modify its vocal output, such as birdsong or human speech, due to experience. The pathways used in the production and modification of human speech and birdsong have been shown to be quite similar, and so, the determining the transcriptome changes in songbirds provide a logical first step to learn more about human speech development. In the current study, trained Zebra Finches, a passerine songbird, were allowed to progress through only the initial stage of vocal development, as determined by a pitch increase compared with untrained isolates. The transcriptomes of the four song nuclei and three auditory forebrain regions of these two groups were compared using microarray hybridizations, and the results were confirmed using in situ hybridization. In Area X, part of the anterior forebrain pathway known to play a role in vocal learning, 149 genes were found to be differentially regulated, with approximately 85% of these genes decreasing in expression. Of the differentially expressed genes, some have already been found to play a role, either directly or indirectly, in learning through previous studies, though most have still yet to have their properties determined. This study, though important in and of itself, is only the first of many pieces to the large process of vocal learning to be put into place; further work will be able to expand upon work here to fill in gaps in our knowledge of the vocal learning process

Spherical collapse model in agegraphic dark energy cosmologies

Under the commonly used spherical collapse model, we study how dark energy affects the growth of large scale structures of the Universe in the context of agegraphic dark energy models. The dynamics of the spherical collapse of dark matter halos in nonlinear regimes is determined by the properties of the dark energy model. We show that the main parameters of the spherical collapse model are directly affected by the evolution of dark energy in the agegraphic dark energy models. We compute the spherical collapse quantities for different values of agegraphic model parameter $\alpha$ in two different scenarios: first, when dark energy does not exhibit fluctuations on cluster scales, and second, when dark energy inside the overdense region collapses similar to dark matter. Using the Sheth-Tormen and Reed mass functions, we investigate the abundance of dark matter halos in the framework of agegraphic dark energy cosmologies. The model parameter $\alpha$ is a crucial parameter in order to count the abundance of dark matter halos. Specifically, the present analysis suggests that the agegraphic dark energy model with bigger (smaller) value of $\alpha$ predicts less (more) virialized halos with respect to that of $\Lambda$CDM cosmology. We also show that in agegraphic dark energy models, the number of halos strongly depends on clustered or uniformed distributions of dark energy.Comment: 14 pages, 7 figures. Accepted in Physical Review

Smad4 regulates growth plate matrix production and chondrocyte polarity.

Smad4 is an intracellular effector of the TGFβ family that has been implicated in Myhre syndrome, a skeletal dysplasia characterized by short stature, brachydactyly and stiff joints. The TGFβ pathway also plays a critical role in the development, organization and proliferation of the growth plate, although the exact mechanisms remain unclear. Skeletal phenotypes in Myhre syndrome overlap with processes regulated by the TGFβ pathway, including organization and proliferation of the growth plate and polarity of the chondrocyte. We used in vitro and in vivo models of Smad4 deficiency in chondrocytes to test the hypothesis that deregulated TGFβ signaling leads to aberrant extracellular matrix production and loss of chondrocyte polarity. Specifically, we evaluated growth plate chondrocyte polarity in tibiae of Col2-Cre+/-;Smad4fl/fl mice and in chondrocyte pellet cultures. In vitro and in vivo, Smad4 deficiency decreased aggrecan expression and increased MMP13 expression. Smad4 deficiency disrupted the balance of cartilage matrix synthesis and degradation, even though the sequential expression of growth plate chondrocyte markers was intact. Chondrocytes in Smad4-deficient growth plates also showed evidence of polarity defects, with impaired proliferation and ability to undergo the characteristic changes in shape, size and orientation as they differentiated from resting to hypertrophic chondrocytes. Therefore, we show that Smad4 controls chondrocyte proliferation, orientation, and hypertrophy and is important in regulating the extracellular matrix composition of the growth plate