440 research outputs found
Full-Thickness Central Corneal Grafts in Lamellar Keratoscleroplasty to Treat Limbal Dermoids
No full textDevelopment and evaluation of the HDFG Editor: An application for graph visualization and modification
No full textReconfigurable computing is a technique used to speed up computer programs by using a combination of hardware and software implementation. The Delft workbench is a tool chain for reconfigurable computing, making it possible to design software without knowledge of the underlying hardware. One function of this tool chain is to convert source code to a hardware description. The DWARV toolset performs this function. While doing so, it uses Hierarchical Data Flow Graphs (HDGFs), which contain data dependencies in the original source code. HDGFs only exist in a binary format and there is no easy way to modify them. This thesis describes the design process of a program, the HDFG Editor. This process consists of a few steps. First, the functional and non-functional requirements were determined. To prevent improper interpretation of the requirements, a set of use cases was created and prioritized. Next, an analysis of available applications and libraries took place. A concept user interface was also designed to get an idea of the visual outline of the application at an early stage. With the decision of Irrlicht as a graphics engine the implementation could commence. Implementation of an application entails creating algorithms and analyzing code. With adaptability as a main focus point some trade-offs were made concerning run-time as scripts are sometimes preferred to code. Concluding, the running time for the project proved to be insufficient to finish the HDFG Editor. Part of the functionality has been implemented but not enough to put to the program to use. However, the work done provides a solid base should the project be picked up in the future.Electrical Engineering, Mathematics and Computer Scienc
scheme #43
No full textThis project concerns a graduation project from the department of materialisation: Strategic Architectural Design Development (SADD). The design focuses upon a new UN council in New York City: the United Nations Environmental Council (UNEC) which is placed in the north lawn, next to the current UN Headquarters. The building contains a mixed program of functions which are coherent to the building’s main function: to collect research material (library), to produce policies (offices), to propagate to citizens (auditoria) and to exchange knowledge to countries (the main council room). Due to the very nature of the building varies sustainable solutions are architecturally integrated in the design.Materialisation: Strategic Architectural Design Development (SADD)ArchitectureArchitectur
Search for two-neutrino double electron capture on 124Xe with the XMASS-I detector
Full text linkDouble electron capture is a rare nuclear decay process in which two orbital electrons are captured simultaneously in the same nucleus. Measurement of its two-neutrino mode would provide a new reference for the calculation of nuclear matrix elements whereas observation of its neutrinoless mode would demonstrate lepton number violation. A search for two-neutrino double electron capture on 124Xe is performed using 165.9 days of data collected with the XMASS-I liquid xenon detector. No significant excess above background was observed and we set a lower limit on the half-life as 4.7×1021 years at 90% confidence level. The obtained limit has ruled out parts of some theoretical expectations. We obtain a lower limit on the 126Xe two-neutrino double electron capture half-life of 4.3×1021 years at 90% confidence level as well. © 2016 The Author(s)1851sciescopu
Direct dark matter search by annual modulation in XMASS-I
Full text linkA search for dark matter was conducted by looking for an annual modulation signal due to the Earth's rotation around the Sun using XMASS, a single phase liquid xenon detector. The data used for this analysis was 359.2 live days times 832 kg of exposure accumulated between November 2013 and March 2015. When we assume Weakly Interacting Massive Particle (WIMP) dark matter elastically scattering on the target nuclei, the exclusion upper limit of the WIMP-nucleon cross section 4.3×10-41 cm2 at 8 GeV/c2 was obtained and we exclude almost all the DAMA/LIBRA allowed region in the 6 to 16 GeV/c2 range at ~10-40 cm2. The result of a simple modulation analysis, without assuming any specific dark matter model but including electron/γ events, showed a slight negative amplitude. The p-values obtained with two independent analyses are 0.014 and 0.068 for null hypothesis, respectively. We obtained 90% C.L. upper bounds that can be used to test various models. This is the first extensive annual modulation search probing this region with an exposure comparable to DAMA/LIBRA. © 2016 The Author(s)115211sciescopu
Función del represor capicua en la Interpretación de señales RTK-Ras-MAPK en "Drosophila"
Full text link[spa] Las señales receptor tirosina kinasa (RTK) controlan un amplio abanico de decisiones durante el desarrollo de un animal, como la proliferación celular, diferenciación, morfogénesis y supervivencia. Muchas de estas señales se transducen a través de la cascada de Ras-MAPK que en última instancia fosforilan un factor de transcripción regulando la expresión de distintos genes. Los mecanismos moleculares por los que la señalización por RTKs inducen repuestas tan diversas permanecen aún sin esclarecer. Los efectores de la vía más estudiados en Drosophila son Pointed y Yan donde en ausencia de señalización, los genes diana se mantienen reprimidos por Yan, mientras que la actividad de la vía fosforila Pointed y Yan, resultando en la activación transcripcional a través de la asociación de Pointed al ADN. Estudios más recientes han mostrado que otro de los factores fosforilado por la vía es Capicua (Cic). Cic es un represor materno que es fosforilado por la MAPK y esta fosforilación dirige la desactivación de la proteína.
En este trabajo, hemos mostrado que las secuencias de unión a Cic en sus genes diana representan un mecanismo general de interpretación de la señal por Ras-MAPK. Hemos descrito el mecanismo por el que la vía de Torso regula los genes huckebein (hkb) y tailless (tll) a través de la desactivación de Cic en los polos del embrión en el estadio de blastodermo sincitial. La expresión restringida de tll y hkb a los polos del embrión por la proteína Cic, permite la expresión de genes del tronco para la correcta segmentación del eje A/P del animal. Además, hemos definido una nueva diana de Cic en el eje dorsoventral (D/V) del embrión, intermediate neuroblast defective (ind), que alberga la función de diferenciar la células que dan lugar a los neuroblastos intermedios del sistema nervioso central.
Experimentos adicionales nos han permitido describir el mecanismo por el que Cic regula el gen argos en repuesta a la señalización por EGFR, en el disco imaginal de ala. En este contexto, al contrario que en los casos del embrión, la desactivación de la proteína Cic en respuesta a la vía de EGFR no es el único mecanismo por el que se induce el gen diana. Trabajos posteriores tendrán que explicar esta red de regulaciones más compleja.
Además de la identificación de la secuencia de unión de Cic a los elementos reguladores de sus genes diana, hemos estudiado el papel del correpresor Groucho (Gro) en la regulación de hkb. Trabajos anteriores habían implicado a Gro en la regulación de los genes hkb y tll ya que embriones mutantes para gro muestran un patrón expandido de estos genes terminales. Este patrón, es muy similar al que se observa en embriones mutantes cic por lo que se ha sugerido que Gro podría actuar junto a Cic para la regulación de hkb y tll. Nosotros hemos podido demostrar que los lugares de unión de Cic en el enhancer de hkb son importantes para reclutar Gro al ADN. Este resultado nos indica que Gro está actuando a través de Cic para mediar la represión y no a través de otro factor que también pudiera regular la expresión de hkb.
La señalización por EGFR en las células dorsoanteriores del ovario está implicada en el establecimiento del eje D/V a través de la represión del gen pipe (pip) en esta región. Nosotros hemos podido demostrar que esta regulación ocurre de manera análoga a la del embrión. Cic reprime los represores inducidos por la vía de señalización, Tll y Mirror (Mirr) en el embrión y ovario respectivamente, para posibilitar la expresión de sus genes diana, Kruppel (Kr) y pip, y así determinar las regiones que les corresponden como el tronco en el embrión y la región ventral en el ovario.
Por otro lado hemos descrito un nuevo mecanismo por el que los substratos de la MAPK compiten entre ellos por la fosforilación por debajo de la vía de Torso. Así, hemos explicado la razón por la que aún habiendo más MAPK fosforilada en el polo anterior del embrión, existe una menor desactivación de Cic y cómo este efecto puede afectar la regulación de los genes diana.[eng] "The function of Capicua repressor in the interpretation of RTK-Ras-MAPK signaling in Drosophila". Receptor tyrosine kinase (RTK) signaling pathways control multiple decisions during Drosophila development such as proliferation, differentiation, morphogenesis, and survival. Many RTKs signal through the very well conserved Ras-MAPK cassette that ultimately phosphorylate a nuclear factor altering the transcriptional output in many different contexts. The molecular mechanisms that lead to so many different outputs are still under study.
In this work we have analyzed the molecular mechanism by which Capicua (Cic), a recently described downstream repressor of the pathway, regulates gene expression in different contexts. We found that the Cic binding sites represent a general mechanism of Ras-MAPK signaling interpretation. Cic is downregulated in the cells with active signaling pathway alleviating the repression on its target genes. In the cells with no active signaling, Cic is repressing its targets localizing their expression to restricted patterns. We showed that Cic regulates huckebein (hkb) and tailless (tll) expression at the poles of the blastoderm embryo allowing a correct A/P axis formation. hkb regulation by Cic requires the association to the global co-repressor Gro. We also found that Cic regulates intermediate neuroblast defective (ind) gene in the D/V axis of the embryo for the intermediate neuroblast formation and it regulates argos (aos) gene expression in the wing imaginal disc for a stereotyped wing vein pattern formation.
We also showed that the mechanism by which the EGFR signaling pathway restricts pipe (pip) expression to the ventral follicle cells of the ovary is analogous to that occurring in the embryo: Cic restricts mirr expression to the cells with active EGFR signaling in the dorsoanterior follicle cells to allow the expression of its target, pip, in the ventral region.
Finally, we also showed a novel mechanism by which MAPK substrates compete for the phosphorylation, and this mechanism explains why in the anterior pole of the embryo, containing higher concentration of phosphorylated MAPK, Cic protein concentration is higher
BRICS in Africa: promoting development
Full text linkSummary of the discussion held at the book launch at Exclusive Books, V&A Waterfront, 11 OctoberAn enlightening book launch was held at Exclusive Books in the V&A Waterfront, featuring a distinguished panel including the book's co-editors Krish Chetty, Dr. Yul Derek Davids, and contributing
author Dr. Jaya Josie. The event centred around their new book, which delves into the intricate
dynamics of BRICS (Brazil, Russia, India, China, and South Africa) nations and their influence on African
development.N/
A measurement of the scintillation decay time constant of nuclear recoils in liquid xenon with the XMASS-I detector
No full textWe report an in-situ measurement of the nuclear recoil (NR) scintillation decay time constant in liquid xenon (LXe) using the XMASS-I detector at the Kamioka underground laboratory in Japan. XMASS-I is a large single-phase LXe scintillation detector whose purpose is the direct detection of dark matter via NR which can be induced by collisions between Weakly Interacting Massive Particles (WIMPs) and a xenon nucleus. The inner detector volume contains 832 kg of LXe. 252Cf was used as an external neutron source for irradiating the detector. The scintillation decay time constant of the resulting neutron induced NR was evaluated by comparing the observed photon detection times with Monte Carlo simulations. Fits to the decay time prefer two decay time components, one for each of the Xe2 ∗ singlet and triplet states, with τS = 4.3 ± 0.6 ns taken from prior research, τT was measured to be 26.9+0.7 -1.1 ns with a singlet state fraction FS of 0.252+0.027 -0.019. We also evaluated the performance of pulse shape discrimination between NR and electron recoil (ER) with the aim of reducing the electromagnetic background in WIMP searches. For a 50% NR acceptance, the ER acceptance was 13.7±1.0% and 4.1±0.7% in the energy ranges of 5-10 keVee and 10-15 keVee, respectively. © 2018 The Author(s
A flat lens with tunable phase gradient by using random access reconfigurable metamaterial
No full textThe first demonstration of an optofluidic metamaterial is reported where resonant properties of every individual metamolecule can be continuously tuned at will using a microfluidic system. This is called a random-access reconfigurable metamaterial, which is used to provide the first demonstration of a tunable flat lens with wavefront-reshaping capabilities
MICRO-MECHANICAL ANALYSIS OF THE KNEE-POINT ON TENSION STRESS-STRAIN CURVE OF COMPOSITES
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