611 research outputs found
Mutations in pericentrin cause Seckel syndrome with defective ATR-dependent DNA damage signaling.
No full textContains fulltext :
70806.pdf (Publisher’s version ) (Closed access)Large brain size is one of the defining characteristics of modern humans. Seckel syndrome (MIM 210600), a disorder of markedly reduced brain and body size, is associated with defective ATR-dependent DNA damage signaling. Only a single hypomorphic mutation of ATR has been identified in this genetically heterogeneous condition. We now report that mutations in the gene encoding pericentrin (PCNT)--resulting in the loss of pericentrin from the centrosome, where it has key functions anchoring both structural and regulatory proteins--also cause Seckel syndrome. Furthermore, we find that cells of individuals with Seckel syndrome due to mutations in PCNT (PCNT-Seckel) have defects in ATR-dependent checkpoint signaling, providing the first evidence linking a structural centrosomal protein with DNA damage signaling. These findings also suggest that other known microcephaly genes implicated in either DNA repair responses or centrosomal function may act in common developmental pathways determining human brain and body size
ATR-FTIR in catalysis: Study of homogeneous, heterogeneous and biocatalysts
No full textThis work discusses the use of ATR-FTIR in catalysis. Besides development and critical analysis of the method, several catalytic systems have been studied.ChemEApplied Science
REFLECTIONS ON ATR.
No full textAuthor Institution: Infrared Department Grubb ParsonsIn 1951 Simon published a paper on Spectroscopy in the Infrared by Reflection and computed the reflecting power of an absorbing medium, both for light polarized parallel to and light polarized perpendicular to the plane of incidence. Two angles of incidence were chosen, with a wide range of values of index of absorption and refractive index. However, the full practical possibilities of the technique were not realized at the time and it was not until 1961 that Fahrenfort published his first paper on the use of ATR to obtain infrared spectra. This publication aroused great interest since new sampling techniques for the infrared region are few and far between. Since 1961 a great deal of ingenuity has gone into the design of expensive devices to exploit ATR techniques. The theoretical aspects of ATR are now re-examined and it is concluded that some of the more complicated and expensive designs of attachment give little advantage over simpler types. Micro ATR and multi-reflection ATR systems are also considered and their uses and limitations discussed
An essential role for MCL-1 in ATR-mediated CHK1 phosphorylation
No full textHere we report a novel role for myeloid cell leukemia 1 (Mcl-1), a Bcl-2 family member, in regulating phosphorylation and activation of DNA damage checkpoint kinase, Chk1. Increased expression of nuclear Mcl-1 and/or a previously reported short nuclear form of Mcl-1, snMcl-1, was observed in response to treatment with low concentrations of etoposide or low doses of UV irradiation. We showed that after etoposide treatment, Mcl-1 could coimmunoprecipitate with the regulatory kinase, Chk1. Chk1 is a known regulator of DNA damage response, and its phosphorylation is associated with activation of the kinase. Transient transfection with Mcl-1 resulted in an increase in the expression of phospho-Ser345 Chk1, in the absence of any evidence of DNA damage, and accumulation of cells in G2. Importantly, knockdown of Mcl-1 expression abolished Chk1 phosphorylation in response to DNA damage. Mcl-1 could induce Chk1 phosphorylation in ATM-negative (ataxia telangectasia mutated) cells, but this response was lost in ATR (AT mutated and Rad3 related)-defective cells. Low levels of UV treatment also caused transient increases in Mcl-1 levels and an ATR-dependent phosphorylation of Chk1. Together, our results strongly support an essential regulatory role for Mcl-1, perhaps acting as an adaptor protein, in controlling the ATR-mediated regulation of Chk1 phosphorylation.Peer reviewedfinal article publishe
In Situ ATR-FTIR Investigation of Photodegradation of 3,4-Dihydroxybenzoic Acid on TiO2
No full textThe catalytic photo-oxidation of 3,4-dihydroxybenzoic acid on TiO2 has been studied by in situ ATR-FTIR in flowing water and in flowing wet air/nitrogen gas. In flowing water it was difficult to observe photodegradation intermediates despite photocatalytic action during UV illumination. In the flowing wet air/nitrogen system carboxylic acids and carbonates were observed. It was shown that water plays an important role in the formation of oxidation active species. Oxygen shows a prominent role for carboxylic acid degradation, but the photogenerated hole plays the important role for the 3,4-dihydroxybenzoic acid ring cleavage
Kinetics of chemisorption and physisorption in liquid phase using a microfluidic ATR-FTIR flow cell
No full textThis thesis describes the development and application of an Attenuated Total Reflection Fourier Transform-Infrared (ATR FT-IR) microflow cell for the study of liquid-solid sorption kinetics, relevant for heterogeneous (photo)catalysis.Chemical EngineeringApplied Science
In Situ ATR-SEIRAS of Carbon Dioxide Reduction at a Plasmonic Silver Cathode
No full textIllumination of a voltage-biased plasmonic Ag cathode during CO2 reduction results in a suppression of the H2 evolution reaction while enhancing CO2 reduction. This effect has been shown to be photonic rather than thermal, but the exact plasmonic mechanism is unknown. Here, we conduct an in situ ATR-SEIRAS (attenuated total reflectance-surface-enhanced infrared absorption spectroscopy) study of a sputtered thin film Ag cathode on a Ge ATR crystal in CO2-saturated 0.1 M KHCO3 over a range of potentials under both dark and illuminated (365 nm, 125 mW cm-2) conditions to elucidate the nature of this plasmonic enhancement. We find that the onset potential of CO2 reduction to adsorbed CO on the Ag surface is -0.25 VRHE and is identical in the light and the dark. As the production of gaseous CO is detected in the light near this onset potential but is not observed in the dark until -0.5 VRHE, we conclude that the light must be assisting the desorption of CO from the surface. Furthermore, the HCO3- wavenumber and peak area increase immediately upon illumination, precluding a thermal effect. We propose that the enhanced local electric field that results from the localized surface plasmon resonance (LSPR) is strengthening the HCO3- bond, further increasing the local pH. This would account for the decrease in H2 formation and increase the CO2 reduction products in the light.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.ChemE/Materials for Energy Conversion and StorageLarge Scale Energy Storag
The Google Book search settlement: A law and economics analysis
No full textBeginning in December 2004 Google has pursued a new project to create a book search engine (Google Book Search). The project has released a storm of controversy around the globe. While the supporters of Google Book Search conceive the project as a first reasonable step towards unlimited access to knowledge in the information age, its opponents fear profound negative effects due to an erosion of copyright law. Our law and economics analysis of the Book Search Project suggests that – from a copyright perspective – the proposed settlement may be beneficial to right holders, consumers, and Google. For instance, it may provide a solution to the still unsolved dilemma of orphan works. From a competition policy perspective, we stress the important aspect that Google’s pricing algorithm for orphan and unclaimed works effectively replicates a competitive Nash-Bertrand market outcome under post-settlement, third-party oversight.Book Rights Registry; Competition Policy; Copyright; Fair Use; Google Book Search; Library Program; Orphan Works
Radar target micro-doppler signature classification
No full textThis thesis reports on research into the field of Micro-Doppler Signature (μ-DS) based radar Automatic
Target Recognition (ATR) with additional contributions to general radar ATR methodology. The μ-DS based part of the research contributes to three distinct areas: time domain classification; frequency domain classification; and multiperspective μ-DS classification that includes the development of a theory for the multistatic μ-DS. The contribution to general radar ATR is the proposal of a methodology to allow better evaluation of potential approaches and to allow comparison between different studies.
The proposed methodology is based around a “black box” model of a radar ATR system that, critically, includes a threshold to detect inputs that are previously unknown to the system. From this model a set of five evaluation metrics are defined. The metrics increase the understanding of the classifier’s performance from the common probability of correct classification, that reports how often the classifier correctly identifies an input, to understanding how reliable it is, how capable it is of generalizing from
the reference data, and how effective its unknown input detection is. Additionally, the significance of performance prediction is discussed and a preliminary method to estimate how well a classifier should perform is developed. The proposed methodology is then used to evaluate the μ-DS based radar ATR approaches considered.
The time domain classification investigation is based around using Dynamic Time Warping (DTW) to identify radar targets based on their μ-DS. DTW is a speech processing technique that classifies data series by comparing them with a pre-classified reference dataset. This is comparable to the common k-Nearest Neighbour (k-NN) algorithm, so k-NN is used as a benchmark against which to evaluate DTW’s
performance. The DTW approach is observed to work well. It achieved high probability of correct classification and reliability as well as being able to detect inputs of unknown class. However, the classifier’s ability to generalize from the reference data is less impressive and it performed only slightly better than a random selection from the possible output classes. Difficulties in classifying the μ-DS in the time domain are identified from the k-NN results prompting a change to the frequency domain.
Processing the μ-DS in the frequency domain permitted the development of an advanced feature extraction routine to maximize the separation of the target classes and therefore reduce the effort required to classify them. The frequency domain also permitted the use of the performance prediction method developed as part of the radar ATR methodology and the introduction of a na¨ıve Bayesian approach to classification. The results for the DTW and k-NN classifiers in the frequency domain were comparable
to the time domain, an unexpected result since it was anticipated that the μ-DS would be easier to classify in the frequency domain. However, the naıve Bayesian classifier produced excellent results that matched with the predicted performance suggesting it could not be bettered. With a successful classifier, that would be suitable for real-world use, developed attention turned to the possibilities offered by the multistatic μ-DS.
Multiperspective radar ATR uses data collected from different target aspects simultaneously to improve
classification rates. It has been demonstrated successful for some of the alternatives to μ-DS based ATR and it was therefore speculated that it might improve the performance of μ-DS ATR solutions.
The multiple perspectives required for the classifier were gathered using a multistatic radar developed at University College London (UCL). The production of a dataset, and its subsequent analysis, resulted in the first reported findings in the novel field of the multistatic μ-DS theory. Unfortunately, the nature of the radar used resulted in limited micro-Doppler being observed in the collected data and this reduced its value for classification testing. An attempt to use DTW to perform multiperspective μ-DS ATR was
made but the results were inconclusive. However, consideration of the improvements offered by multiperspective processing in alternative forms of ATR mean it is still expected that μ-DS based ATR would
benefit from this processing
Estudio sobre el soporte polimérico sintético usado por el pintor contemporáneo portugués Daniel Vasconcelos Melim
No full textThe research presented here aims to identify the synthetic polymer used by the contemporary Portuguese painter Daniel Vasconcelos Melim as a support for his paintings made in acrylic paint, to study its physical and chemical properties and to identify the most frequent change phenomena. For the identification and comparative study of the synthetic polymer used, the following tests were performed: Visible and Ultraviolet Spectroscopy (UV-Vis); Fourier Transform Infrared Spectroscopy with Attenuated Total Reflection (HATR-FTIR); density measurements and solubility tests in different solvents; pyrolysis and flame tests. and the organic solvent extraction method with a Soxhlet extractor on samples of RENOLIT - SE brand thermoplastic membranes from different years, namely 2011 and 2018. Aging tests were also carried out on membrane samples for 67 days at room temperature of 21 oC and at a temperature of 70 oC in order to identify some phenomena of alteration, such as: colour change and loss of mass.La investigación que aquí se presenta tiene como objetivos: identificar el polímero sintético utilizado por el pintor portugués contemporáneo Daniel Vasconcelos Melim como soporte para sus cuadros de pintura acrílica, estudiar algunas de sus propiedades fisicoquímicas e identificar los fenómenos de alteración más frecuentes. Para el estudio identificativo y comparativo del polímero sintético utilizado por el artista, se recurrió a la Espectroscopía en el Ultravioleta-visible (UV-Vis), a la Espectroscopia de Infrarrojo con Transformada de Fourier y con Reflexión Total Atenuada (ATR - FTIR), a mediciones de densidad, a ensayos de solubilidad en diferentes disolventes, a las pruebas de pirólisis y de llama, y al método de extracción con Soxhlet con disolvente orgánico, en muestras de membranas termoplásticas de la marca RENOLIT - SE de años distintos, especialmente de 2011 y de 2018. Se realizaron pruebas de envejecimiento en muestras de membrana durante 67 días, a temperatura ambiente de 21 oC y la temperatura de 70 oC para identificar algunos fenómenos de alteración, tales como: alteración del color y pérdida de masa.Os polímeros sintéticos termoplásticos estão presentes não só nas vivências quotidianas, mas também em obras de arte. Dado o ímpeto experimental dos artistas contemporâneos em utilizar nas suas obras materiais diversificados e não convencionais, muitas vezes materiais de construção, como é o caso de tintas acrílicas utilizadas em interiores, membranas plásticas para cobertura, componentes elétricos, mobiliário, entre outros, torna-se necessário identificar estes polímeros. A identificação passa pelo estudo das suas características e do seu comportamento perante alguns agentes exteriores, tais como: a radiação ultravioleta e visível (UV-V), a temperatura, a humidade ambiente ou mesmo em alguns casos, a água no estado líquido e o oxigénio.
A investigação que aqui se apresenta tem como objetivos: identificar o plástico utilizado pelo pintor português Daniel Vasconcelos Melim como suporte para as suas pinturas a tinta acrílica; estudar algumas das suas propriedades físico-químicas e identificar os fenómenos de alteração mais frequentes.
A investigação que aqui se apresenta tem como objetivos: identificar o tipo de polímero sintético utilizado pelo pintor português Daniel Vasconcelos Melim como suporte para as suas pinturas a tinta acrílica; estudar algumas das suas propriedades físico-químicas e identificar os fenómenos de alteração mais frequentes. Para o estudo identificativo e comparativo do polímero sintético utilizado pelo artista, recorreu-se à Espectroscopia no Ultravioleta-visível (UV-Vis), à Espectroscopia de Infravermelho com Transformada de Fourier (FTIR) e Reflexão Total Atenuada (ATR-FTIR), à medição da densidade e a ensaios de solubilidade em diferentes solventes, a testes de pirólise e de chama e ao método de extração com um Soxhlet e com solvente orgânico, em amostras de membranas termoplásticas da marca RENOLIT - SE de anos distintos, nomeadamente de 2011 e de 2018. Realizaram-se ainda testes de envelhecimento em amostras de membrana durante 67 dias, à temperatura ambiente de 21 oC e à temperatura de 70 oC de forma a identificar alguns fenómenos de alteração, tais como: alteração da cor e perda de massa
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