3,840 research outputs found
Dynamics of X Chromosome Inactivation
__Abstract__
Dosage compensation evolved to account for the difference in expression of sex chromosome-linked genes. In mammals dosage compensation is achieved by inactivation of one X chromosome during early female embryogenesis in a process called X chromosome inactivation (XCI). Central players in this process are two overlapping antisense transcribed noncoding genes, Xist and Tsix. The nature of this XCI process places this field of research at the interface between stem cell biology, epigenetics and gene regulation. The aim of this thesis is to shed further light onto the different levels of regulation that ensure faithful initiation and maintenance of XCI in a developmental context. These different levels include transcription factors, noncoding RNAs, antisense transcription, and epigenetic processes including DNA methylation, histone modifications and chromosomal conformation. In the first part we analyze trans- and cis-acting networks that regulate the initiation of XCI. Classical transcription factors and their regulators, most prominently the ubiquitin ligase RNF12 and its primary target in ES cells, REX1, have an essential function during initiation and early maintenance of XCI. Moreover, our deletion and transgene studies argue that many of the noncoding RNAs located in the Xic predominantly function in cis, and that X chromosome pairing events are not necessary for XCI to occur. We also utilize Xist and Tsix reporter lines to study the dynamics of Xist and Tsix re
Structure-acidity-IR spectra correlations for p-substituted N-phenylsulfonylbenzamides
The wavenumbers of the IR absorption bands of the C=O, S=O and N-H stretching vibrations for a series of p-substituted N-phenylsulfonylbenzamides were measured in trichloromethane. The bond orders, Mulliken charges, charge densities and heats of formation were calculated using the PM3 method. Fifty significant mutual mono parameter (MP) and six dual parameter (DP) correlations were found for the IR spectral, theoretical structural data, substituent constants and previously reported dissociation constants in five polar organic solvents. The transmission of the substituent effects has been discussed and the solvent effect on the slopes of some linear correlations was evaluated using different solvent parameters. The results showed that the factors describing the electronic structure and controlling the dissociation equilibrium and the IR spectra properties of p-substituted N-phenylsulfonylbenzamides must be the same
High-density correlation energy expansion of the one-dimensional uniform electron gas
We show that the expression of the high-density (i.e small-) correlation
energy per electron for the one-dimensional uniform electron gas can be
obtained by conventional perturbation theory and is of the form \Ec(r_s) =
-\pi^2/360 + 0.00845 r_s + ..., where is the average radius of an
electron. Combining these new results with the low-density correlation energy
expansion, we propose a local-density approximation correlation functional,
which deviates by a maximum of 0.1 millihartree compared to the benchmark DMC
calculations.Comment: 7 pages, 2 figures, 3 tables, accepted for publication in J. Chem.
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Очистка воды от солей жёсткости при помощи бытового водоочитстного фильтра
В работе проведено исследование фильтра-кувшина Аквафор Гарри, при процессах динамической фильтрации, через него водопроводной воды содержащей соли жёсткости. Определена степень извлечения солей жёсткости и ресурс исследуемого картриджа В100-8.In this work, a study of the filter-jar Aquaphor Harry was carried out in the process of dynamic filtration of tap water containing hardness salts. The degree of extraction of hardness salts and the working life of the investigated cartridge B100-8 was determined
Weighted Bergman kernels and virtual Bergman kernels
We introduce the notion of "virtual Bergman kernel" and apply it to the
computation of the Bergman kernel of "domains inflated by Hermitian balls", in
particular when the base domain is a bounded symmetric domain.Comment: 12 pages. One-hour lecture for graduate students, SCV 2004, August
2004, Beijing, P.R. China. V2: typo correcte
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https://digitalcommons.library.umaine.edu/mmb-vp/5972/thumbnail.jp
Uniform electron gases
We show that the traditional concept of the uniform electron gas (UEG) --- a
homogeneous system of finite density, consisting of an infinite number of
electrons in an infinite volume --- is inadequate to model the UEGs that arise
in finite systems. We argue that, in general, a UEG is characterized by at
least two parameters, \textit{viz.} the usual one-electron density parameter
and a new two-electron parameter . We outline a systematic
strategy to determine a new density functional across the
spectrum of possible and values.Comment: 8 pages, 2 figures, 5 table
Classification of Quantitative Light-Induced Fluorescence Images Using Convolutional Neural Network
Images are an important data source for diagnosis and treatment of oral
diseases. The manual classification of images may lead to misdiagnosis or
mistreatment due to subjective errors. In this paper an image classification
model based on Convolutional Neural Network is applied to Quantitative
Light-induced Fluorescence images. The deep neural network outperforms other
state of the art shallow classification models in predicting labels derived
from three different dental plaque assessment scores. The model directly
benefits from multi-channel representation of the images resulting in improved
performance when, besides the Red colour channel, additional Green and Blue
colour channels are used.Comment: Full version of ICANN 2017 submissio
In vitro Digestibility Study of Starch Complexed with Different Guest Molecules
Digestibility of starch is an essential issue in food science studies due to its close relationship with human health. Most common starchy foods contain rapidly digestible starch, which can lead to chronic diseases, including type II diabetes. Heat–moisture treated potato starch (HPS) followed by inclusion complexation with guest molecules is prepared to improve starch's physicochemical properties, resulting in reduced digestibility. The guest molecules used in this study are linoleic acid (LA), stearic acid (SA), and sodium stearate (SS). The in vitro digestibility of the modified starches over time compared to native starch after gelatinization at 95 °C is examined. The starch complexed with SS results in the least amount of rapidly digestible starch (RDS), followed by LA and SA, consecutively. Furthermore, the starch-SS complexes are the most slowly digestible starch (SDS) and included the highest amount of resistant starch (RS), followed by LA and SA. Sodium stearate results in the highest transformation of RDS to be SDS and RS. Thermal analysis data and microscopy images support the digestion results
Physicochemical properties of heat-moisture treated, sodium stearate complexed starch:The effect of sodium stearate concentration
Amylose‑sodium stearate (SS) complexes (2, 5 and 8%) in heat-moisture treated potato starch (HPS) were evaluated for their physicochemical properties. Based on the DSC thermograms, the amylose - SS complexes were successfully formed with high thermal stability, indicated by a melt temperature (Tpeak) of ≥ 112 °C for type I and ≥125 °C for type II complexes. Addition of 2% SS resulted in a single endothermal peak of the complexes, while 5 and 8% led to the formation of type I and II complexes with much higher enthalpy (ΔH) values. The XRD curve confirmed that the complexes were successfully formed. The pasting temperature increased from 66 °C for native to 91 °C for HPS145 complexed starch with 5% SS. Furthermore, the swelling power could be largely decreased, and the granular structure preserved. In addition, the inclusion complexation with SS on (HPS) succesfully improved the cook stabiliy
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