2,201 research outputs found
Multiple Spatial Frequencies Pyramid WaveFront Sensing
A modification of the pyramid wavefront sensor is described. In this conceptually new class of devices, the perturbations are split at the level of the focal plane depending upon their spatial frequencies, and then measured separately. The aim of this approach is to increase the accuracy in the determination of some range of spatial frequency perturbations, or a certain classes of modes, disentangling them from the noise associated to the Poissonian fluctuations of the light coming from the perturbations outside of the range of interest or from the background in the pupil planes; the latter case specifically when the pyramid wavefront sensor is used with a large modulation. While the limits and the effectiveness of this approach should be further investigated, a number of variations on the concept are shown, including a generalization of the spatial filtering in the point-diffraction wavefront sensor. The simplest application, a generalization to the pyramid of the well-known spatially filtering in wavefront sensing, is showing promise as a significant limiting magnitude advance. Applications are further speculated in the area of extreme adaptive optics and when serving spectroscopic instrumentation where “light in the bucket” rather than Strehl performance is required
Ingot Laser Guide Stars Wavefront Sensing
We revisit one class of z-invariant WaveFront sensor where the LGS is fired
aside of the telescope aperture. In this way there is a spatial dependence on
the focal plane with respect to the height where the resonant scattering
occurs. We revise the basic parameters involving the geometry and we propose
various merit functions to define how much improvement can be attained by a
z-invariant approach. We show that refractive approaches are not viable and we
discuss several solutions involving reflective ones in what has been nicknamed
"ingot wavefront sensor" discussing the degrees of freedom required to keep
tracking and the basic recipe for the optical design.Comment: 6 pages, 4 figures, AO4ELT5 Conference Proceeding, 201
A Holographic Diffuser Generalised Optical Differentiation Wavefront Sensor
The wavefront sensors used today at the biggest World's telescopes have
either a high dynamic range or a high sensitivity, and they are subject to a
linear trade off between these two parameters. A new class of wavefront
sensors, the Generalised Optical Differentiation Wavefront Sensors, has been
devised, in a way not to undergo this linear trade off and to decouple the
dynamic range from the sensitivity. This new class of WFSs is based on the
light filtering in the focal plane from a dedicated amplitude filter, which is
a hybrid between a linear filter, whose physical dimension is related to the
dynamic range, and a step in the amplitude, whose size is related to the
sensitivity. We propose here a possible technical implementation of this kind
of WFS, making use of a simple holographic diffuser to diffract part of the
light in a ring shape around the pin of a pyramid wavefront sensor. In this
way, the undiffracted light reaches the pin of the pyramid, contributing to the
high sensitivity regime of the WFS, while the diffused light is giving a sort
of static modulation of the pyramid, allowing to have some signal even in high
turbulence conditions. The holographic diffuser zeroth order efficiency is
strictly related to the sensitivity of the WFS, while the diffusing angle of
the diffracted light gives the amount of modulation and thus the dynamic range.
By properly choosing these two parameters it is possible to build a WFS with
high sensitivity and high dynamic range in a static fashion. Introducing
dynamic parts in the setup allows to have a set of different diffuser that can
be alternated in front of the pyramid, if the change in the seeing conditions
requires it.Comment: 11 pages, 5 figure
Multiple spatial frequencies wavefront sensing
We describe the concept of splitting spatial frequency perturbations into
some kind of pupil planes wavefront sensors. Further to the existing approach
of dropping higher spatial frequency to suppress aliasing effects (the
so-called spatial filtered Shack-Hartmann), we point out that spatial
frequencies splitting and mixing of these in a proper manner, could be handled
in order to exhibit some practical or fundamental advantages. In this framework
we describe the idea behind such class of concepts and we derive the
relationship useful to determine if, by which extent, and under what kind of
merit function, these devices can overperform existing conventional sensors.Comment: 6 pages, 3 figures, in AO4ELT5 Proceeding
Prospects of Deep Field Surveys with Global-MCAO on an ELT
Several astronomical surveys aimed at the investigation of the extragalactic
components were carried out in order to map systematically the universe and its
constituents. An excellent level of detail is needed, and it is possible only
using space telescopes or with the application of adaptive optics (AO)
techniques for ground-based observatories. By simulating K-band observations of
6000 high-redshift galaxies in the Chandra Deep Field South region, we have
already shown how an extremely large telescope can carry out photometric
surveys successfully using the Global-MCAO, a natural guide stars based
technique that allows the development of extragalactic research, otherwise
impracticable without using laser guide stars. As the outcome of the analysis
represents an impact science case for the new instruments on upcoming
ground-based telescopes, here we show how the investigation of other observed
deep fields could profit from such a technique. Further to an overview of the
surveys suitable for the proposed approach, we show preliminary estimations
both on geometrical (FoV and height) and purely AO perspectives (richness and
homogeneity of guide stars in the area) for planned giant telescope.Comment: 8 pages, 6 figures, AO4ELT5 conferenc
Transcriptomic and genomic studies classify NKL54 as a histone deacetylase inhibitor with indirect influence on MEF2-dependent transcription
In leiomyosarcoma class IIa HDACs (histone deacetylases) bind MEF2 and convert these transcription factors into repressors to sustain proliferation. Disruption of this complex with small molecules should antagonize cancer growth. NKL54, a PAOA (pimeloylanilide o-aminoanilide) derivative, binds a hydrophobic groove of MEF2, which is used as a docking site by class IIa HDACs. However, NKL54 could also act as HDAC inhibitor (HDACI). Therefore, it is unclear which activity is predominant. Here, we show that NKL54 and similar derivatives are unable to release MEF2 from binding to class IIa HDACs. Comparative transcriptomic analysis classifies these molecules as HDACIs strongly related to SAHA/vorinostat. Low expressed genes are upregulated by HDACIs, while abundant genes are repressed. This transcriptional resetting correlates with a reorganization of H3K27 acetylation around the transcription start site (TSS). Among the upregulated genes there are several BH3-only family members, thus explaining the induction of apoptosis. Moreover, NKL54 triggers the upregulation of MEF2 and the downregulation of class IIa
HDACs. NKL54 also increases the binding of MEF2D to promoters of genes that are upregulated after treatment. In summary, although NKL54 cannot outcompete MEF2 from binding to class IIa HDACs, it supports MEF2-dependent transcription through several actions, including potentiation of chromatin binding
Il link asma-obesitĂ : aspetti patogenetici, clinico-funzionali e diagnostico-terapeutici
L’asma e l’obesità sono considerate un problema primario di salute pubblica dell’età infantile, che sta assumendo proporzioni globalmente “epidemiche”. Diversi studi epidemiologici hanno chiaramente evidenziato la presenza di un’associazione tra le due patologie. Tale complessa interazione patogenetica vede coinvolti fattori genetici, di sviluppo, di funzione
polmonare, immunologici e comportamentali; alcuni di essi sono ad oggi ancora poco studiati e conosciuti. Per tale motivo, non è possibile identificare un meccanismo prevalente sugli altri che sia alla base della relazione causale tra le due patologie. Il crescente interesse scientifico nei confronti dell’associazione tra asma e obesitĂ ha contribuito a delineare diversi fenotipi di patologia presenti nelle varie epoche della vita. La caratterizzazione clinica dei soggetti asmatici obesi è presupposto fondamentale per identificare terapie mirate a raggiungere il controllo dell’asma e contemporaneamente a ridurre il peso del soggetto prevenendo le complicanze legate all’obesitĂ
Preliminar study of the effects of gamma radiations on human red blood cells
En este estudio se analizaron los parámetros viscoelásticos y de agregaciĂłn en glĂłbulos rojos humanos sometidos a los procedimientos habituales de irradiaciĂłn gamma con fines transfusionales. Las muestras fueron irradiadas a diferentes dosis a fin de determinar los posibles cambios hemorreolĂłgicos que pudieran afectar a la salud de los pacientes y su relaciĂłn con las modificaciones bioquĂmicas observadas. Los resultados obtenidos muestran alteraciones en el tiempo de agregaciĂłn, en la viscosidad superficial de membrana y en el tamaño de los agregados eritrocitarios en las muestras irradiadas, sugiriendo que el daño producido por la radiaciĂłn ionizante afecta a las propiedades fĂsicas de la membrana del glĂłbulo rojo en diferentes nivelesIn this study, the alterations in viscoelastic and aggregation parameters of red blood cells were analyzed for usual gamma irradiation procedures for transfusion purposes. In order to determine possible hemorheological changes that may affect the health of patients and their relationship with the biochemical changes observed, the blood samples were irradiated at different doses. The results show alterations in the erythrocyte aggregation time, in the membrane surface viscosity and in the size of the aggregates in the irradiated samples, suggesting that the damage produced by the ionizing radiation affects the physical properties of red blood cell membrane at different levels.Fil: Estrada, E.. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Rosario. Instituto de FĂsica de Rosario. Universidad Nacional de Rosario. Instituto de FĂsica de Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Exactas, IngenierĂa y Agrimensura; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas; ArgentinaFil: Castellini, H.. Universidad Nacional de Rosario. Facultad de Ciencias Exactas, IngenierĂa y Agrimensura; ArgentinaFil: Acosta, A.. Centro Regional de Hemoterapia; ArgentinaFil: Di Tullio, L.. Centro Regional de Hemoterapia de Rosario; ArgentinaFil: Borraz, J.. Centro Regional de Hemoterapia de Rosario; ArgentinaFil: Chinellato, A.. Centro Regional de Hemoterapia de Rosario; ArgentinaFil: Tack, I.. Centro Regional de Hemoterapia de Rosario; ArgentinaFil: D'Arrigo, M.. Universidad Nacional de Rosario. Facultad de Ciencias Exactas, IngenierĂa y Agrimensura; ArgentinaFil: Riquelme, Bibiana Doris. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Rosario. Instituto de FĂsica de Rosario. Universidad Nacional de Rosario. Instituto de FĂsica de Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas; ArgentinaFil: Galassi, Mariel Elisa. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Rosario. Instituto de FĂsica de Rosario. Universidad Nacional de Rosario. Instituto de FĂsica de Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Exactas, IngenierĂa y Agrimensura; Argentin
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