| 1. |
- Klionsky, Daniel J., et al.
(författare)
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Guidelines for the use and interpretation of assays for monitoring autophagy
- 2012
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Ingår i: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 8:4, s. 445-544
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Forskningsöversikt (refereegranskat)abstract
- In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
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| 2. |
- Marini Bettolo, Cecilia, 1978-
(författare)
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Performance Studies and Star Tracking for PoGOLite
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- PoGOLite is a balloon-borne experiment, which will study polarized soft γ-ray emissionfrom astrophysical targets in the 25-80 keV energy range by applying well-typephoswich detector technology. Polarized γ-rays are expected from a wide variety of sources including rotation-powered pulsars, accreting black holes and neutron stars,and jet-dominated active galaxies. Polarization measurements provide a powerfulprobe of the γ-ray emission mechanism and the distribution of magnetic and radiation fields around the source. The polarization is determined using Compton scattering and photoelectric absorption in an array of 217 plastic scintillators. The sensitive detector is surrounded by a segmented Bismuth Germanium Oxide (BGO) anticoincidence shield. The function of this shield is to reduce backgrounds from charged cosmic rays, primary and atmospheric γ-rays, and atmospheric and instrumenta lneutrons. The anticoincidence shield consists of 427 BGO crystals with three different geometries. The characteristics of the BGO crystals of the bottom anticoincidence shield have been studied with particular focus on the light yield.The maiden flight of PoGOLite will be with a reduced detector volume “pathfinder” instrument. The flight, lasting about 24 hours, is foreseen from Esrange, Sweden in August 2010. The performance of the pathfinder has been studied using computer simulations. The effect of atmospheric attenuation, both on the signal of theastronomical target and on the background, are studied. These allow an observationstrategy to be developed for the forthcoming flight. A polarization analysis method is described and applied to an observation example. The method sets anupper limit on the accuracy with which the polarimeter will be able to detect polarization the angle and degree. The PoGOLite polarimeter has a relatively small field of view (2.4◦×2.4◦) which must be kept aligned to objects of interest on the sky. A star tracker forms part of the attitude control system. The star trackersystem comprises a CCD camera, a lens, and a baffle system. Preliminary studiesof the star identification performance are presented and are found to be compatible with the environment around the Crab, which is the main observational target for the first flight.
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| 3. |
- McConnell, M. L., et al.
(författare)
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POET : A SMEX mission for gamma ray burst polarimetry
- 2014
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Ingår i: Proceedings of SPIE, the International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 9144
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Tidskriftsartikel (refereegranskat)abstract
- Polarimeters for Energetic Transients (POET) is a mission concept designed to t within the envelope of a NASA Small Explorer (SMEX) mission. POET will use X-ray and gamma-ray polarimetry to uncover the energy release mechanism associated with the formation of stellar-mass black holes and investigate the physics of extreme magnetic ields in the vicinity of compact objects. Two wide-FoV, non-imaging polarimeters will provide polarization measurements over the broad energy range from about 2 keV up to about 500 keV. A Compton scatter polarimeter, using an array of independent scintillation detector elements, will be used to collect data from 50 keV up to 500 keV. At low energies (215 keV), data will be provided by a photoelectric polarimeter based on the use of a Time Projection Chamber for photoelectron tracking. During a two-year baseline mission, POET will be able to collect data that will allow us to distinguish between three basic models for the inner jet of gamma-ray bursts.
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