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Search Results: 1 - 10 of 4946 matches for " Christoph Redies "
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Restricted expression of classic cadherins in the spinal cord of the chicken embryo
Juntang Lin,Christoph Redies
Frontiers in Neuroanatomy , 2014, DOI: 10.3389/fnana.2014.00018
Abstract: Classic cadherins belong to the family of cadherin genes and play important roles in neurogenesis, neuron migration, and axon growth. In the present study, we compared the expression patterns of 10 classic cadherins (Cdh2, Cdh4, Cdh6, Cdh7, Cdh8, Cdh9, Cdh11, Cdh12, Cdh18, and Cdh20) in the developing chicken spinal cord (SP) by in situ hybridization. Our results indicate that each of the investigated cadherins exhibits a spatially restricted and temporally regulated pattern of expression. At early developmental stages (E2.5–E3), Cdh2 is expressed throughout the neuroepithelial layer. Cdh6 is strongly positive in the roof plate and later also in the floor plate. Cdh7, Cdh11, Cdh12, and Cdh20 are expressed in restricted regions of the basal plate of the SP. At intermediate stages of development (E4–E10), specific expression profiles are observed for all investigated cadherins in the differentiating mantle layer along the dorsoventral, mediolateral, and rostrocaudal dimensions. Expression profiles are especially diverse for Cdh2, Cdh4, Cdh8, Cdh11, and Cdh20 in the dorsal horn, while different pools of motor neurons exhibit signal for Cdh6, Cdh7, Cdh8, Cdh9, Cdh12, and Cdh20 in the ventral horn. Interestingly, subpopulations of cells in the dorsal root ganglion express combinations of different cadherins. In the surrounding tissues, such as the boundary cap cells and the notochord, the cadherins are also expressed differentially. The highly regulated spatiotemporal expression patterns of the classic cadherins indicate that these genes potentially play multiple and diverse roles during the development of the SP and its surrounding tissues.
1/f2 Characteristics and Isotropy in the Fourier Power Spectra of Visual Art, Cartoons, Comics, Mangas, and Different Categories of Photographs
Michael Koch,Joachim Denzler,Christoph Redies
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0012268
Abstract: Art images and natural scenes have in common that their radially averaged (1D) Fourier spectral power falls according to a power-law with increasing spatial frequency (1/f2 characteristics), which implies that the power spectra have scale-invariant properties. In the present study, we show that other categories of man-made images, cartoons and graphic novels (comics and mangas), have similar properties. Further on, we extend our investigations to 2D power spectra. In order to determine whether the Fourier power spectra of man-made images differed from those of other categories of images (photographs of natural scenes, objects, faces and plants and scientific illustrations), we analyzed their 2D power spectra by principal component analysis. Results indicated that the first fifteen principal components allowed a partial separation of the different image categories. The differences between the image categories were studied in more detail by analyzing whether the mean power and the slope of the power gradients from low to high spatial frequencies varied across orientations in the power spectra. Mean power was generally higher in cardinal orientations both in real-world photographs and artworks, with no systematic difference between the two types of images. However, the slope of the power gradients showed a lower degree of mean variability across spectral orientations (i.e., more isotropy) in art images, cartoons and graphic novels than in photographs of comparable subject matters. Taken together, these results indicate that art images, cartoons and graphic novels possess relatively uniform 1/f2 characteristics across all orientations. In conclusion, the man-made stimuli studied, which were presumably produced to evoke pleasant and/or enjoyable visual perception in human observers, form a subset of all images and share statistical properties in their Fourier power spectra. Whether these properties are necessary or sufficient to induce aesthetic perception remains to be investigated.
Expression of classic cadherins and δ-protocadherins in the developing ferret retina
Johannes Etzrodt, K Krishna-K, Christoph Redies
BMC Neuroscience , 2009, DOI: 10.1186/1471-2202-10-153
Abstract: All cadherins investigated by us are expressed differentially by restricted populations of retinal cells during specific periods of the ferret retinogenesis. For example, during embryonic development, some cadherins are exclusively expressed in the outer, proliferative zone of the neuroblast layer, whereas other cadherins mark the prospective ganglion cell layer or cells in the prospective inner nuclear layer. These expression patterns anticipate histogenetic changes that become visible in Nissl or nuclear stainings at later stages. In parallel to the ongoing development of retinal circuits, cadherin expression becomes restricted to specific subpopulations of retinal cell types, especially of ganglion cells, which express most of the investigated cadherins until adulthood. A comparison to previous results in chicken and mouse reveals overall conserved expression patterns of some cadherins but also species differences.The spatiotemporally restricted expression patterns of 7 classic cadherins and 8 δ-protocadherins indicate that cadherins provide a combinatorial adhesive code that specifies developing retinal cell populations and intraretinal as well as retinofugal neural circuits in the developing ferret retina.The vertebrate retina develops as a ventral outgrowth of the forebrain vesicle; invagination of the primary optic vesicle leads to a two-layered optic cup that differentiates into an outer, pigmented epithelium and an inner, multilayered, neural epithelium, which is the focus of our study. The mature neural retina comprises distinct sets of neurons, each with a characteristic morphology, location and connectivity. Together, they form a highly sophisticated network, arranged in distinct layers [reviewed in [1,2]]. Retinal development involves the processes of cellular proliferation, migration and differentiation. These processes are mediated by molecular mechanisms similar to those in the rest of the brain.Many studies have investigated the organization and dev
Asymmetric N-Cadherin Expression Results in Synapse Dysfunction, Synapse Elimination, and Axon Retraction in Cultured Mouse Neurons
Kim N. Pielarski, Bernd van Stegen, Aksana Andreyeva, Katja Nieweg, Kay Jüngling, Christoph Redies, Kurt Gottmann
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0054105
Abstract: Synapse elimination and pruning of axon collaterals are crucial developmental events in the refinement of neuronal circuits. While a control of synapse formation by adhesion molecules is well established, the involvement of adhesion molecules in developmental synapse loss is poorly characterized. To investigate the consequences of mis-match expression of a homophilic synaptic adhesion molecule, we analysed an asymmetric, exclusively postsynaptic expression of N-cadherin. This was induced by transfecting individual neurons in cultures of N-cadherin knockout mouse neurons with a N-cadherin expression vector. 2 days after transfection, patch-clamp analysis of AMPA receptor-mediated miniature postsynaptic currents revealed an impaired synaptic function without a reduction in the number of presynaptic vesicle clusters. Long-term asymmetric expression of N-cadherin for 8 days subsequently led to synapse elimination as indicated by a loss of colocalization of presynaptic vesicles and postsynaptic PSD95 protein. We further studied long-term asymmetric N-cadherin expression by conditional, Cre-induced knockout of N-cadherin in individual neurons in cultures of N-cadherin expressing cortical mouse neurons. This resulted in a strong retraction of axonal processes in individual neurons that lacked N-cadherin protein. Moreover, an in vivo asymmetric expression of N-cadherin in the developmentally transient cortico-tectal projection was indicated by in-situ hybridization with layer V neurons lacking N-cadherin expression. Thus, mis-match expression of N-cadherin might contribute to selective synaptic connectivity.
Previs?o do número de dias de chuva para a metade sul do Rio Grande do Sul utilizando a Temperatura da Superfície do Mar (TSM)
Fischer, Graciela Redies;Diniz, Gilberto Barbosa;Marques, Julio Renato Quevedo;
Revista Brasileira de Meteorologia , 2008, DOI: 10.1590/S0102-77862008000200003
Abstract: this study presents a climate forecasting model of the number of rainfall days (nrd) for some meteorological stations in rio grande do sul using the sea surface temperatures (sst) as the predictable variables. two sets of data were used in this research: the monthly data of nrd, which were obtained from 5 meteorological stations located in the southern half of rio grande do sul, in the period of 1982 until 2005; and the sst data, measured in the same period. this series was divided in two periods: the dependent period is from 1982 to 2002, and it was used to determine the predictable equations and the regression coefficients; and the independent period, which is from 2003 to 2005, and was used to validate the model. the sst data were employed to establish the relations between the variables through the regression analysis. good results were obtained in the prediction of the nrd for the regions and all the months analyzed. the predictable and observed data had a very similar distribution of the variables. although there was some predictable values that differed from the observed ones, but these differences were not significant. the higher differences between the foreseen and the observed values occurred in the independent period.
Establishing Payment Hubs—Unwind the Spaghetti?  [PDF]
Christoph Markert
American Journal of Industrial and Business Management (AJIBM) , 2014, DOI: 10.4236/ajibm.2014.44024
Abstract:

Banks and financial services providers are facing a more and more competitive business within the retail banking as well as corporate market. Increasing productivity and efficiency by decreasing operational costs is very often one milestone on the strategic business roadmap of a bank or financial services providers. The payment area is usually seen as a cost intensive, but necessary part of the business and information technology (IT) landscape. Many banks and financial services providers do still follow a best-of-breed approach within the system payments landscape, which ends up in high operational and maintenance costs as different payment processing platforms are serving different business purposes. The establishment of a single globally centralized payment hub cannot be only the solution for the ending of a heterogeneous payment processing landscape, but also for supporting the strategic management roadmap by decreasing system complexity and increasing the efficiency of the payment platforms and thus decreasing operational and maintenance IT costs. Furthermore it can support banks to establish a far more flexible technological implementation approach for an entire core banking transformation program. This paper is analyzing the challenges and issues banks and financial services providers are facing with the establishment of payment hubs in their enterprise system landscape from a management as well as IT point of view.

Determination of Material Properties like Permittivity and Density with Microwaves  [PDF]
Christoph Sklarczyk
Journal of Modern Physics (JMP) , 2014, DOI: 10.4236/jmp.2014.56043
Abstract:

With the help of electromagnetic waves in deci-, centi- and millimeter-wave range (microwaves) it is possible to determine the properties of non-metallic objects like permittivity or density in a nondestructive and if necessary in a contactless way. Depending on the type of the test object the measurement can be carried out both with low-cost narrowband or more expensive wideband devices and sensors. To get the characteristic value in most cases it is necessary to calibrate the test device with the help of reference materials. It is recommendable to sustain a constant distance (lift-off or standoff) between the antenna of the sensor and the test object. The paper deals with the characterization of asphalt, especially the determination of its density.

Photon Structure Function Revisited  [PDF]
Christoph Berger
Journal of Modern Physics (JMP) , 2015, DOI: 10.4236/jmp.2015.68107
Abstract: The flux of papers from electron positron colliders containing data on the photon structure function \"\"ended naturally around 2005. It is thus timely to review the theoretical basis and confront the predictions with a summary of the experimental results. The discussion will focus on the increase of the structure function with x (for x away from the boundaries) and its rise with \"\", both characteristics being dramatically different from hadronic structure functions. The agreement of the experimental observations with the theoretical calculations is a striking success of QCD. It also allows a new determination of the QCD coupling constant \"\"which very well corresponds to the values quoted in the literature.
Optimal Costly Information Gathering in Public Service Provision  [PDF]
Paul Geertsema, Christoph Schumacher
Theoretical Economics Letters (TEL) , 2012, DOI: 10.4236/tel.2012.23060
Abstract: Imperfect information regarding the true needs of recipients is a common problem for governmental or not-for-profit service providers. This can lead to potentially dangerous under-provision or wasteful over-provision of services. We provide a method for optimally improving a service provider’s information regarding true client need through costly information gathering. Our contribution is to allow providers to endogenously and optimally choose the intensity of information gathering. Providers do so by specifying the level of correlation between observed and true recipient need, subject to an arbitrary cost function over the specified correlation. We derive the conditions that characterize the choice of optimal correlation for providers with quadratic utility. Using a realistic exponential correlation cost function, we show that there exists a critical value of true client need variance below which it is never optimal to engage in information gathering. Further, for true client variance above this critical level the optimal correlation will always exceed 0.5. Our findings have a wide range of policy implications in areas such as health care, social wellfare and even counter-terroism.
Relative importance of different physical processes on upper crustal specific heat flow in the Eifel-Maas region, Central Europe and ramifications for the production of geothermal energy  [PDF]
Lydia Dijkshoorn, Christoph Clauser
Natural Science (NS) , 2013, DOI: 10.4236/ns.2013.52A039
Abstract:

We study the recent upper crustal heat flow variations caused by long-term physical processes such as paleoclimate, erosion, sedimentation and mantle plume upwelling. As specific heat flow is a common lower boundary condition in many models of heat en fluid flow in the Earth’s crust we quantify its long-term transient variation caused by paleoclimate, erosion or sedimentation, mantle plume upwelling and deep groundwater flow. The studied area extends between the Eifel mountains and the Maas river inCentral Europe. The total variation due to these processes in our study area amounts to tectonic events manifested in the studied area 20 mW/m2, about 30% of the present day specific heat flow in the region.

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