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Senescence, aging, and malignant transformation mediated by p53 in mice lacking the Brca1 full-length isoform

Cao, Liu; Li, Wenmei; Kim, Sangsoo; Brodie, Steven G.; Deng, Chu-Xia
Fonte: Cold Spring Harbor Laboratory Press Publicador: Cold Spring Harbor Laboratory Press
Tipo: Artigo de Revista Científica
Publicado em 15/01/2003 EN
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Senescence may function as a two-edged sword that brings unexpected consequences to organisms. Here we provide evidence to support this theory by showing that the absence of the Brca1 full-length isoform causes senescence in mutant embryos and cultured cells as well as aging and tumorigenesis in adult mice. Haploid loss of p53 overcame embryonic senescence but failed to prevent the adult mutant mice from prematurely aging, which included decreased life span, reduced body fat deposition, osteoporosis, skin atrophy, and decreased wound healing. We further demonstrate that mutant cells that escaped senescence had undergone clonal selection for faster proliferation and extensive genetic/molecular alterations, including overexpression of cyclin D1 and cyclin A and loss of p53. These observations provide the first in vivo evidence that links cell senescence to aging due to impaired function of Brca1 at the expense of tumorigenesis.

Full and partial genome-wide assembly and disassembly of the yeast transcription machinery in response to heat shock

Zanton, Sara J.; Pugh, B. Franklin
Fonte: Cold Spring Harbor Laboratory Press Publicador: Cold Spring Harbor Laboratory Press
Tipo: Artigo de Revista Científica
Publicado em 15/08/2006 EN
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Eukaryotic genes are controlled by sequence-specific DNA-binding proteins, chromatin regulators, general transcription factors, and elongation factors. Here we examine the genome-wide location of representative members of these groups and their redistribution when the Saccharomyces cerevisiae genome is reprogrammed by heat shock. As expected, assembly of active transcription complexes is coupled to eviction of H2A.Z nucleosomes, and disassembly is coupled to the return of nucleosomes. Remarkably, a large number of promoters assemble into partial preinitiation complexes (partial PICs), containing TFIIA, TFIID (and/or SAGA), TFIIB, TFIIE, and TFIIF. However, RNA polymerase II and TFIIH are generally not recruited, and nucleosomes are not displaced. These promoters may be preparing for additional stress that naturally accompany heat stress. For example, we find that oxidative stress, which often occurs with prolonged exposure of cells to high temperature, converts partial PICs into full PICs. Partial PICs therefore represent novel regulated intermediates that assemble at promoters in the midst of chromatin.

From discovery to production: Scale-out of continuous flow meso reactors

Styring, Peter; Parracho, Ana I R
Fonte: Beilstein-Institut Publicador: Beilstein-Institut
Tipo: Artigo de Revista Científica
Publicado em 09/06/2009 EN
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A continuous flow parallel reactor system has been developed to provide a rapid and seamless transition from the discovery phase and production phase of chemical synthesis, particularly in low volume-high value pharmaceuticals production. Using a single fixed bed catalytic meso reactor, reactions can be screened on a small discovery scale over short time scales. The intensified process produces sufficient material for a full analysis. By replication of the single reactor in parallel, the same chemistry can be achieved on a larger scale, on a small footprint and without the mass and heat transport limitations of reactor scale-out in batch.

Predicting the UV–vis spectra of oxazine dyes

Fleming, Scott; Mills, Andrew; Tuttle, Tell
Fonte: Beilstein-Institut Publicador: Beilstein-Institut
Tipo: Artigo de Revista Científica
Publicado em 15/04/2011 EN
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In the current work we have investigated the ability of time-dependent density functional theory (TD-DFT) to predict the absorption spectra of a series of oxazine dyes and the effect of solvent on the accuracy of these predictions. Based on the results of this study, it is clear that for the series of oxazine dyes an accurate prediction of the excitation energy requires the inclusion of solvent. Implicit solvent included via a polarizable continuum approach was found to be sufficient in reproducing the excitation energies accurately in the majority of cases. Moreover, we found that the SMD solvent model, which is dependent on the full electron density of the solute without partitioning into partial charges, gave more reliable results for our systems relative to the conductor-like polarizable continuum model (CPCM), as implemented in Gaussian 09. In all cases the inclusion of solvent reduces the error in the predicted excitation energy to <0.3 eV and in the majority of cases to <0.1 eV.

Laterally substituted symmetric and nonsymmetric salicylideneimine-based bent-core mesogens

Findeisen-Tandel, Sonja; Weissflog, Wolfgang; Baumeister, Ute; Pelzl, Gerhard; Murthy, H N Shreenivasa; Yelamaggad, Channabasaveshwar V
Fonte: Beilstein-Institut Publicador: Beilstein-Institut
Tipo: Artigo de Revista Científica
Publicado em 24/01/2012 EN
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Bent-core mesogens have gained considerable importance due to their ability to form new mesophases with unusual properties. Relationships between the chemical structure of bent-core molecules and the type and physical properties of the formed mesophases are relatively unknown in detail and differ strongly from those known for calamitic liquid crystals. In this paper symmetric and nonsymmetric five-ring salicylideneaniline-based bent-core mesogens are presented, and the effect of lateral substituents attached at the outer phenyl rings (F, Cl, Br) or the central phenyl ring (CH3) on the liquid-crystalline behaviour and on the physical properties is studied. Corresponding benzylideneaniline-based compounds were additionally prepared in order to study the influence of the intramolecular hydrogen bond. The occurring mesophases were investigated by differential scanning calorimetry, polarising microscopy, X-ray diffraction and dielectric and electro-optical measurements. The paper reports on new findings with respect to the structure–property relationships of bent-core mesogens. On one hand, the disruptive effect of laterally substituted halogen atoms, F, Cl and Br, on the mesophase behaviour of three isomeric series was much lower than expected. On the other hand...

Revealing the importance of meristems and roots for the development of hypersensitive responses and full foliar resistance to Phytophthora infestans in the resistant potato cultivar Sarpo Mira

Orłowska, Elżbieta; Basile, Alessio; Kandzia, Izabela; Llorente, Briardo; Kirk, Hanne Grethe; Cvitanich, Cristina
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
EN
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The defence responses of potato against Phytophthora infestans were studied using the highly resistant Sarpo Mira cultivar. The effects of plant integrity, meristems, and roots on the hypersensitive response (HR), plant resistance, and the regulation of PR genes were analysed. Sarpo Mira shoots and roots grafted with the susceptible Bintje cultivar as well as non-grafted different parts of Sarpo Mira plants were inoculated with P. infestans. The progress of the infection and the number of HR lesions were monitored, and the regulation of PR genes was compared in detached and attached leaves. Additionally, the antimicrobial activity of plant extracts was assessed. The presented data show that roots are needed to achieve full pathogen resistance, that the removal of meristems in detached leaves inhibits the formation of HR lesions, that PR genes are differentially regulated in detached leaves compared with leaves of whole plants, and that antimicrobial compounds accumulate in leaves and roots of Sarpo Mira plants challenged with P. infestans. While meristems are necessary for the formation of HR lesions, the roots of Sarpo Mira plants participate in the production of defence-associated compounds that increase systemic resistance. Based on the literature and on the presented results...

An Electronic Measurement Instrumentation of the Impedance of a Loaded Fuel Cell or Battery

Aglzim, El-Hassane; Rouane, Amar; El-Moznine, Reddad
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 17/10/2007 EN
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In this paper we present an inexpensive electronic measurement instrumentation developed in our laboratory, to measure and plot the impedance of a loaded fuel cell or battery. Impedance measurements were taken by using the load modulation method. This instrumentation has been developed around a VXI system stand which controls electronic cards. Software under Hpvee® was developed for automatic measurements and the layout of the impedance of the fuel cell on load. The measurement environment, like the ambient temperature, the fuel cell temperature, the level of the hydrogen, etc…, were taken with several sensors that enable us to control the measurement. To filter the noise and the influence of the 50Hz, we have implemented a synchronous detection which filters in a very narrow way around the useful signal. The theoretical result obtained by a simulation under Pspice® of the method used consolidates the choice of this method and the possibility of obtaining correct and exploitable results. The experimental results are preliminary results on a 12V vehicle battery, having an inrush current of 330A and a capacity of 40Ah (impedance measurements on a fuel cell are in progress, and will be the subject of a forthcoming paper). The results were plotted at various nominal voltages of the battery (12.7V...

Send-On-Delta Concept: An Event-Based Data Reporting Strategy

Miskowicz, Marek
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 20/01/2006 EN
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The paper addresses the issue of the send-on-delta data collecting strategy to capture information from the environment. Send-on-delta concept is the signal-dependent temporal sampling scheme, where the sampling is triggered if the signal deviates by delta defined as the significant change of its value. It is an attractive scheme for wireless sensor networking due to effective energy consumption. The quantitative evaluations of send-on-delta scheme for a general type continuous-time bandlimited signal are presented in the paper. The bounds on the mean traffic of reports for a given signal, and assumed sampling resolution, are evaluated. Furthermore, the send-on-delta effectiveness, defined as the reduction of the mean rate of reports in comparison to the periodic sampling for a given resolution, is derived. It is shown that the lower bound of the send-on-delta effectiveness (i.e. the guaranteed reduction) is independent of the sampling resolution, and constitutes the built-in feature of the input signal. The calculation of the effectiveness for standard signals, that model the state evolution of dynamic environment in time, is exemplified. Finally, the example of send-on-delta programming is shown.

Size-dependent characteristics of electrostatically actuated fluid-conveying carbon nanotubes based on modified couple stress theory

Fakhrabadi, Mir Masoud Seyyed; Rastgoo, Abbas; Ahmadian, Mohammad Taghi
Fonte: Beilstein-Institut Publicador: Beilstein-Institut
Tipo: Artigo de Revista Científica
Publicado em 20/11/2013 EN
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The paper presents the effects of fluid flow on the static and dynamic properties of carbon nanotubes that convey a viscous fluid. The mathematical model is based on the modified couple stress theory. The effects of various fluid parameters and boundary conditions on the pull-in voltages are investigated in detail. The applicability of the proposed system as nanovalves or nanosensors in nanoscale fluidic systems is elaborated. The results confirm that the nanoscale system studied in this paper can be properly applied for these purposes.

Envisat Ocean Altimetry Performance Assessment and Cross-calibration

Faugere, Yannice; Dorandeu, Joël; Lefevre, Fabien; Picot, Nicolas; Femenias, Pierre
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 03/03/2006 EN
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Nearly three years of Envisat altimetric observations over ocean are available in Geophysical Data Record (GDR) products. The quality assessment of these data is routinely performed at the CLS Space Oceanography Division in the frame of the CNES Segment Sol Altimétrie et Orbitographie (SSALTO) and ESA French Processing and Archiving Center (F-PAC) activities. This paper presents the main results in terms of Envisat data quality: verification of data availability and validity, monitoring of the most relevant altimeter (ocean1 retracking) and radiometer parameters, assessment of the Envisat altimeter system performances. This includes a cross-calibration analysis of Envisat data with Jason-1, ERS-2 and T/P. Envisat data show good general quality. A good orbit quality and a low level of noise allow Envisat to reach the high level of accuracy of other precise missions such as T/P and Jason-1. Some issues raised in this paper, as the gravity induced orbit errors, will be solved in the next version of GDR products. Some others, as the Envisat Mean Sea Level in the first year, still need further investigation.

A Comparison of Frequency Pullability in Oscillators Using a Single AT-Cut Quartz Crystal and Those Using Two Single AT-Cut Crystals Connected in Parallel with a Series Load Capacitance or Series Load Inductance

Matko, Vojko
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 29/07/2006 EN
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This paper presents a comparison of frequency pullability in oscillators using a single AT-cut crystal and those using two single AT-cut crystals connected in parallel operated with a series load capacitance or series load inductance at fundamental frequencies of 4, 10 and 19 MHz. Pullability describes how the operating frequency may be changed by varying the load capacitance. The paper also gives impedance circuits for both single- and dual-crystal units. The experiment results show that the new approach using two single quartz crystals connected in parallel increases the frequency pulling range by 30-200% depending on the type of oscillator. Also given is the crystal frequency stability at these three frequencies.

Evaluation of the frequency of immunization information system use for public health research

Curran, Eileen A; Bednarczyk, Robert A.; Omer, Saad B
Fonte: Landes Bioscience Publicador: Landes Bioscience
Tipo: Artigo de Revista Científica
EN
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Immunization information systems (IIS) have been useful for consolidating immunization data and increasing coverage, and have the potential to be a valuable resource for immunization research, but the extent which IIS data are used for research purposes has not been evaluated. We reviewed studies conducted using data from federally supported state and city immunization program IIS, and categorized research type based on study objectives to evaluate patterns in the types of research conducted. Research papers using IIS data published between 1999 and July 3, 2012 were identified by searching the CDC IIS publication database and PubMed. These searches produced 304 and 884 papers, respectively, 44 of which were eligible to be included in this evaluation. The most common research category was evaluation of factors associated with vaccine coverage and vaccine coverage estimates (n = 20). This study shows that IIS may not be used to their full potential with regards to research. Further research is needed to determine barriers to using IIS data for research purposes.

Integration of Multiple Data Sources to Simulate the Dynamics of Land Systems

Deng, Xiangzheng; Su, Hongbo; Zhan, Jinyan
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 04/02/2008 EN
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In this paper we present and develop a new model, which we have called Dynamics of Land Systems (DLS). The DLS model is capable of integrating multiple data sources to simulate the dynamics of a land system. Three main modules are incorporated in DLS: a spatial regression module, to explore the relationship between land uses and influencing factors, a scenario analysis module of the land uses of a region during the simulation period and a spatial disaggregation module, to allocate land use changes from a regional level to disaggregated grid cells. A case study on Taips County in North China is incorporated in this paper to test the functionality of DLS. The simulation results under the baseline, economic priority and environmental scenarios help to understand the land system dynamics and project near future land-use trajectories of a region, in order to focus management decisions on land uses and land use planning.

Hierarchical Wireless Multimedia Sensor Networks for Collaborative Hybrid Semi-Supervised Classifier Learning

Wang, Xue; Wang, Sheng; Bi, Daowei; Ding, Liang
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 13/11/2007 EN
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Wireless multimedia sensor networks (WMSN) have recently emerged as one of the most important technologies, driven by the powerful multimedia signal acquisition and processing abilities. Target classification is an important research issue addressed in WMSN, which has strict requirement in robustness, quickness and accuracy. This paper proposes a collaborative semi-supervised classifier learning algorithm to achieve durative online learning for support vector machine (SVM) based robust target classification. The proposed algorithm incrementally carries out the semi-supervised classifier learning process in hierarchical WMSN, with the collaboration of multiple sensor nodes in a hybrid computing paradigm. For decreasing the energy consumption and improving the performance, some metrics are introduced to evaluate the effectiveness of the samples in specific sensor nodes, and a sensor node selection strategy is also proposed to reduce the impact of inevitable missing detection and false detection. With the ant optimization routing, the learning process is implemented with the selected sensor nodes, which can decrease the energy consumption. Experimental results demonstrate that the collaborative hybrid semi-supervised classifier learning algorithm can effectively implement target classification in hierarchical WMSN. It has outstanding performance in terms of energy efficiency and time cost...

Photoactivation of luminescence in CdS nanocrystals

Smyntyna, Valentyn; Semenenko, Bogdan; Skobeeva, Valentyna; Malushin, Nikolay
Fonte: Beilstein-Institut Publicador: Beilstein-Institut
Tipo: Artigo de Revista Científica
Publicado em 25/03/2014 EN
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This paper presents the results of the research on the luminescence of cadmium sulfide nanocrystals (NCs) synthesized by colloid chemistry in a gelatinous matrix. The photostimulation of the short-wavelength emission band with λmax = 480 nm has been detected. It is shown that the determining factor of the photostimulation effect is the adsorption of the water molecules on the surface of NC. The observed effect is explained by the recombination mechanism that is responsible for the short-wavelength emission band.

Probing viscoelastic surfaces with bimodal tapping-mode atomic force microscopy: Underlying physics and observables for a standard linear solid model

Solares, Santiago D
Fonte: Beilstein-Institut Publicador: Beilstein-Institut
Tipo: Artigo de Revista Científica
Publicado em 26/09/2014 EN
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This paper presents computational simulations of single-mode and bimodal atomic force microscopy (AFM) with particular focus on the viscoelastic interactions occurring during tip–sample impact. The surface is modeled by using a standard linear solid model, which is the simplest system that can reproduce creep compliance and stress relaxation, which are fundamental behaviors exhibited by viscoelastic surfaces. The relaxation of the surface in combination with the complexities of bimodal tip–sample impacts gives rise to unique dynamic behaviors that have important consequences with regards to the acquisition of quantitative relationships between the sample properties and the AFM observables. The physics of the tip–sample interactions and its effect on the observables are illustrated and discussed, and a brief research outlook on viscoelasticity measurement with intermittent-contact AFM is provided.

Analysis of Urban-Rural Land-Use Change during 1995-2006 and Its Policy Dimensional Driving Forces in Chongqing, China

Long, Hualou; Wu, Xiuqin; Wang, Wenjie; Dong, Guihua
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 04/02/2008 EN
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This paper analyzes the urban-rural land-use change of Chongqing and its policy dimensional driving forces from 1995 to 2006, using high-resolution Landsat TM (Thematic Mapper) data of 1995, 2000 and 2006, and socio-economic data from both research institutes and government departments. The outcomes indicated that urban-rural land-use change in Chongqing can be characterized by two major trends: First, the non-agricultural land increased substantially from 1995 to 2006, thus causing agricultural land especially farmland to decrease continuously. Second, the aggregation index of urban settlements and rural settlements shows that local urban-rural development experienced a process of changing from aggregation (1995-2000) to decentralization (2000-2006). Chongqing is a special area getting immersed in many important policies, which include the establishment of the municipality directly under the Central Government, the building of Three Gorges Dam Project, the Western China Development Program and the Grain-for-Green Programme, and bring about tremendous influences on its land-use change. By analyzing Chongqing's land-use change and its policy driving forces, some implications for its new policy of ‘Urban-rural Integrated Reform’ are obtained. That is more attentions need to be paid to curbing excessive and idle rural housing and consolidating rural construction land...

Animals as Mobile Biological Sensors for Forest Fire Detection

Sahin, Yasar Guneri
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 04/12/2007 EN
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This paper proposes a mobile biological sensor system that can assist in early detection of forest fires one of the most dreaded natural disasters on the earth. The main idea presented in this paper is to utilize animals with sensors as Mobile Biological Sensors (MBS). The devices used in this system are animals which are native animals living in forests, sensors (thermo and radiation sensors with GPS features) that measure the temperature and transmit the location of the MBS, access points for wireless communication and a central computer system which classifies of animal actions. The system offers two different methods, firstly: access points continuously receive data about animals' location using GPS at certain time intervals and the gathered data is then classified and checked to see if there is a sudden movement (panic) of the animal groups: this method is called animal behavior classification (ABC). The second method can be defined as thermal detection (TD): the access points get the temperature values from the MBS devices and send the data to a central computer to check for instant changes in the temperatures. This system may be used for many purposes other than fire detection, namely animal tracking, poaching prevention and detecting instantaneous animal death.

An EMI Filter Selection Method Based on Spectrum of Digital Periodic Signal

Podbersic, Marko; Matko, Vojko; Segula, Matjaz
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 03/03/2006 EN
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This paper describes a new method for the selection of an appropriate signal line Electromagnetic Interference (EMI) filter. To date, EMI filter selection has been based on the measurement of the radiation of the entire device. The new selection method based on the signal's Fast Fourier Transform (FFT) measurement has proved to be efficient. The EMI filter is optimized separately for each line. The method described in this paper involving a Central Processor Unit (CPU) module demonstrates that the proposed FFT-based selection method is better than the radiation-based one. The radiation level in the frequency range 30 MHz to 1 GHz is lower for approximate 2 – 6 dBμV/m.

Mapping bound plasmon propagation on a nanoscale stripe waveguide using quantum dots: influence of spacer layer thickness

Perera, Chamanei S; Funston, Alison M; Cheng, Han-Hao; Vernon, Kristy C
Fonte: Beilstein-Institut Publicador: Beilstein-Institut
Tipo: Artigo de Revista Científica
Publicado em 19/10/2015 EN
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In this paper we image the highly confined long range plasmons of a nanoscale metal stripe waveguide using quantum emitters. Plasmons were excited using a highly focused 633 nm laser beam and a specially designed grating structure to provide stronger incoupling to the desired mode. A homogeneous thin layer of quantum dots was used to image the near field intensity of the propagating plasmons on the waveguide. We observed that the photoluminescence is quenched when the QD to metal surface distance is less than 10 nm. The optimised spacer layer thickness for the stripe waveguides was found to be around 20 nm. Authors believe that the findings of this paper prove beneficial for the development of plasmonic devices utilising stripe waveguides.