oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2020 ( 109 )

2019 ( 729 )

2018 ( 823 )

2017 ( 757 )

Custom range...

Search Results: 1 - 10 of 463093 matches for " Herman A. Dierick "
All listed articles are free for downloading (OA Articles)
Page 1 /463093
Display every page Item
Dietary Effects on Cuticular Hydrocarbons and Sexual Attractiveness in Drosophila
Tatyana Y. Fedina, Tsung-Han Kuo, Klaus Dreisewerd, Herman A. Dierick, Joanne Y. Yew, Scott D. Pletcher
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0049799
Abstract: Dietary composition is known to have profound effects on many aspects of animal physiology, including lifespan, general health, and reproductive potential. We have previously shown that aging and insulin signaling significantly influence the composition and sexual attractiveness of Drosophila melanogaster female cuticular hydrocarbons (CHCs), some of which are known to be sex pheromones. Because diet is intimately linked to aging and to the activity of nutrient-sensing pathways, we asked how diet affects female CHCs and attractiveness. Here we report consistent and significant effects of diet composition on female CHC profiles across ages, with dietary yeast and sugar driving CHC changes in opposite directions. Surprisingly, however, we found no evidence that these changes affect female attractiveness. Multivariate comparisons among responses of CHC profiles to diet, aging, and insulin signaling suggest that diet may alter the levels of some CHCs in a way that results in profiles that are more attractive while simultaneously altering other CHCs in a way that makes them less attractive. For example, changes in short-chain CHCs induced by a high-yeast diet phenocopy changes caused by aging and by decreased insulin signaling, both of which result in less attractive females. On the other hand, changes in long-chain CHCs in response to the same diet result in levels that are comparable to those observed in attractive young females and females with increased insulin signaling. The effects of a high-sugar diet tend in the opposite direction, as levels of short-chain CHCs resemble those in attractive females with increased insulin signaling and changes in long-chain CHCs are similar to those caused by decreased insulin signaling. Together, these data suggest that diet-dependent changes in female CHCs may be sending conflicting messages to males.
A Versatile Method for Cell-Specific Profiling of Translated mRNAs in Drosophila
Amanda Thomas, Pei-Jung Lee, Justin E. Dalton, Krystle J. Nomie, Loredana Stoica, Mauro Costa-Mattioli, Peter Chang, Sergey Nuzhdin, Michelle N. Arbeitman, Herman A. Dierick
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0040276
Abstract: In Drosophila melanogaster few methods exist to perform rapid cell-type or tissue-specific expression profiling. A translating ribosome affinity purification (TRAP) method to profile actively translated mRNAs has been developed for use in a number of multicellular organisms although it has only been implemented to examine limited sets of cell- or tissue-types in these organisms. We have adapted the TRAP method for use in the versatile GAL4/UAS system of Drosophila allowing profiling of almost any tissue/cell-type with a single genetic cross. We created transgenic strains expressing a GFP-tagged ribosomal protein, RpL10A, under the control of the UAS promoter to perform cell-type specific translatome profiling. The GFP::RpL10A fusion protein incorporates efficiently into ribosomes and polysomes. Polysome affinity purification strongly enriches mRNAs from expected genes in the targeted tissues with sufficient sensitivity to analyze expression in small cell populations. This method can be used to determine the unique translatome profiles in different cell-types under varied physiological, pharmacological and pathological conditions.
Insulin Signaling Mediates Sexual Attractiveness in Drosophila
Tsung-Han Kuo equal contributor,Tatyana Y. Fedina equal contributor,Ingrid Hansen,Klaus Dreisewerd,Herman A. Dierick,Joanne Y. Yew,Scott D. Pletcher
PLOS Genetics , 2012, DOI: 10.1371/journal.pgen.1002684
Abstract: Sexually attractive characteristics are often thought to reflect an individual's condition or reproductive potential, but the underlying molecular mechanisms through which they do so are generally unknown. Insulin/insulin-like growth factor signaling (IIS) is known to modulate aging, reproduction, and stress resistance in several species and to contribute to variability of these traits in natural populations. Here we show that IIS determines sexual attractiveness in Drosophila through transcriptional regulation of genes involved in the production of cuticular hydrocarbons (CHC), many of which function as pheromones. Using traditional gas chromatography/mass spectrometry (GC/MS) together with newly introduced laser desorption/ionization orthogonal time-of-flight mass spectrometry (LDI-MS) we establish that CHC profiles are significantly affected by genetic manipulations that target IIS. Manipulations that reduce IIS also reduce attractiveness, while females with increased IIS are significantly more attractive than wild-type animals. IIS effects on attractiveness are mediated by changes in CHC profiles. Insulin signaling influences CHC through pathways that are likely independent of dFOXO and that may involve the nutrient-sensing Target of Rapamycin (TOR) pathway. These results suggest that the activity of conserved molecular regulators of longevity and reproductive output may manifest in different species as external characteristics that are perceived as honest indicators of fitness potential.
The Rationalization of Automatic Units for HPDC Technology
A. Herman
Archives of Foundry Engineering , 2012, DOI: 10.2478/v10266-012-0031-z
Abstract: The paper deals with problem of optimal used automatic workplace for HPDC technology - mainly from aspects of operations sequence, efficiency of work cycle and planning of using and servicing of HPDC casting machine. Presented are possible ways to analyse automatic units for HPDC. The experimental part was focused on the rationalization of the current work cycle time for die casting of aluminium alloy. The working place was described in detail in the project. The measurements were carried out in detail with the help of charts and graphs mapped cycle of casting workplace. Other parameters and settings have been identified. The proposals for improvements were made after the first measurements and these improvements were subsequently verified. The main actions were mainly software modifications of casting center. It is for the reason that today's sophisticated workplaces have the option of a relatively wide range of modifications without any physical harm to machines themselves. It is possible to change settings or unlock some unsatisfactory parameters.
The Rationalization of Automatic Units for HPDC Technology
A. Herman
Archives of Foundry Engineering , 2012,
Abstract: The paper deals with problem of optimal used automatic workplace for HPDC technology - mainly from aspects of operations sequence, efficiency of work cycle and planning of using and servicing of HPDC casting machine. Presented are possible ways to analyse automatic units for HPDC. The experimental part was focused on the rationalization of the current work cycle time for die casting of aluminium alloy. The working place was described in detail in the project. The measurements were carried out in detail with the help of charts and graphs mapped cycle of casting workplace. Other parameters and settings have been identified.The proposals for improvements were made after the first measurements and these improvements were subsequently verified. The main actions were mainly software modifications of casting center. It is for the reason that today's sophisticated workplaces have the option of a relatively wide range of modifications without any physical harm to machines themselves. It is possible to change settings or unlock some unsatisfactory parameters.
Realistic 3D computer model of the gerbil middle ear, featuring accurate morphology of bone and soft tissue structures
J. A. N. Buytaert,W. H. M. Salih,M. Dierick,P. Jacobs,J. J. J. Dirckx
Quantitative Biology , 2011,
Abstract: In order to improve realism in middle ear (ME) finite element modeling (FEM), comprehensive and precise morphological data are needed. To date, micro-scale X-ray computed tomography (\mu CT) recordings have been used as geometric input data for FEM models of the ME ossicles. Previously, attempts were made to obtain this data on ME soft tissue structures as well. However, due to low X-ray absorption of soft tissue, quality of these images is limited. Another popular approach is using histological sections as data for 3D models, delivering high in-plane resolution for the sections, but the technique is destructive in nature and registration of the sections is difficult. We combine data from high-resolution \mu CT recordings with data from high-resolution orthogonal-plane fluorescence optical-sectioning microscopy (OPFOS), both obtained on the same gerbil specimen. State-of-the-art \mu CT delivers high-resolution data on the three-dimensional shape of ossicles and other ME bony structures, while the OPFOS setup generates data of unprecedented quality both on bone and soft tissue ME structures. Each of these techniques is tomographic and non-destructive, and delivers sets of automatically aligned virtual sections. The datasets coming from different techniques need to be registered with respect to each other. By combining both datasets, we obtain a complete high-resolution morphological model of all functional components in the gerbil ME. The resulting three-dimensional model can be readily imported in FEM software and is made freely available to the research community. In this paper, we discuss the methods used, present the resulting merged model and discuss morphological properties of the soft tissue structures, such as muscles and ligaments.
The Decreasing of Die Cracking for HDPC Technology by Changing Parameters of Heat Treatment
A. Herman,P. Zikmund
Archives of Foundry Engineering , 2012,
Abstract: In earlier works were described trends in the production of tools for die casting (hot work). Almost the entire set of issues dealt with may seem insignificant when incompletely assembled acceptance of the material and the associated risks of processing a material with an inappropriate structure, leading to a very early defect of the die. Therefore, further work will focus particularly on identifying the causes of thermal cracks and preventing a suitable choice of acceptance criteria conditions and heat treatment.
The optimization of working cycles for HPDC technology
A. Herman,P. Zikmund
Archives of Foundry Engineering , 2010,
Abstract: The paper deals with problem of optimal used workplace for HPDC technology - mainly from aspects of operations sequence efficient of work cycle and planning of using and servicing of HPDC casting machine.
Hankel operators plus orthogonal polynomials yield combinatorial identities
E. A. Herman
Online Journal of Analytic Combinatorics , 2009,
Abstract: A Hankel operator $H = [h_{i+j}]$ can be factored as $H = MM^ $, where $M$ maps a space of $L^2$ functions to the corresponding moment sequences. Furthermore, a necessary and sufficient condition for a sequence to be in the range of $M$ can be expressed in terms of an expansion in orthogonal polynomials. Combining these two results yields a wealth of combinatorial identities that incorporate both the matrix entries $h_{i+j}$ and the coefficients of the orthogonal polynomials.
Variability of sea ice deformation rates in the Arctic and their relationship with basin-scale wind forcing
A. Herman,O. Glowacki
The Cryosphere Discussions , 2012, DOI: 10.5194/tcd-6-3349-2012
Abstract: In this paper, temporal variability of the moments of probability distribution functions (pdfs) of total sea ice deformation rates in the Arctic is analyzed in the context of the basin-scale wind forcing acting on the ice. The pdfs are estimated for 594 satellite-derived sea ice deformation maps from 11 winter seasons between 1996/1997 and 2007/2008, provided by the RADARSAT Geophysical Processor System. The moments of the pdfs, calculated for a range of spatial scales, have two dominating components of variability: a seasonal cycle, with deformation rates decreasing throughout winter towards a minimum in March; and a short-term, synoptic variability, strongly correlated with the area-averaged magnitude of the wind stress over the Arctic, estimated based on the NCEP-DOE Reanalysis-2 data (correlation coefficient of 0.71 for the mean deformation rate). Due to scaling properties of the moments, logarithms of higher moments are strongly correlated with the wind stress as well. By demonstrating that a very simple model can provide an explanation for the observed relationships, we show that they reflect the dominating balance of forces in the compact, quasi-stationary ice pack. Finally, we suggest that a positive trend in seasonally-averaged correlation between sea ice deformation rates and the wind forcing, present in the analyzed data, may be related to an observed decrease in the multi-year ice area in the Arctic, indicating possibly even stronger correlations in the future.
Page 1 /463093
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.