3,886 research outputs found
Hydrophobicity, rather than secondary structure, is essential for the SRP dependent targeting of GPR35 to the ER membrane
The folding and targeting of hydrophobic transmembrane domains poses a major challenge to the cell. Several membrane proteins have been shown to gain some degree of secondary structure within the ribosome tunnel and to retain this conformation throughout maturation. However, there is little information on one of the largest classes of eukaryotic membrane proteins; the G protein-coupled receptors (GPCRs). In this study we show that the signal anchor domain of GPR35 remains in an extended conformation whilst exiting the ribosome tunnel, the polypeptide chain then forms interactions with components of the SRP targeting pathway, and the Sec61 translocon, resulting in a compacted conformation prior to integration into the ER membrane. We conclude that transmembrane structure is most likely adopted after the domain leaves the ribosome tunnel and that the interaction of the signal anchor with SRP is dependent on the native levels of hydrophobicity within the first transmembrane domain. Therefore, we propose a mechanism by which the first transmembrane domains of multi-spanning membrane proteins adopt compacted structures following SRP targeting but before insertion into the ER membrane
Eucalyptus largiflorens F. Muell.
https://thekeep.eiu.edu/herbarium_specimens_byname/9502/thumbnail.jp
Eucalyptus largiflorens F. Muell.
https://thekeep.eiu.edu/herbarium_specimens_byname/9502/thumbnail.jp
Low Energy Gamma-Ray Emission from Galactic Black Holes
X-ray observations of Galactic black holes (GBHs) such as Cygnus X-1 have greatly advanced the understanding of these objects. However, the vast majority of the observations have been restricted to energies below ~200 keV. The Compton Gamma-Ray Observatory (CGRO) allowed for the first time simultaneous observations at energies from ~25 keV up to >1 GeV. In particular, the BATSE experiment aboard CGRO was able to monitor low-energy gamma-ray emission from Cygnus X-1, as well as other GBHs, nearly continuously over a nine year period. Using the Enhanced BATSE Occultation Package (EBOP), light curves and spectra in the energy range 25–2000 keV have been obtained for six GBHs. Based on the spectra when the GBHs were in a high gamma-ray flux state, it is suggested that at least two different classes of GBHs exist. The first is characterized by a Comptonization spectrum below ~200 keV followed by a soft power law excess as exhibited by Cygnus X-1, GRO J0422+32, GRO J1719−24, and GX 339-4. The second class is characterized by simple power law spectrum in the full 25–2000 keV range, with no evidence for a Comptonization component, as exhibited by GRO J1655−40 and GRS 1915+105.Gamma-ray observations can serve as an important diagnostic in studying the physical processes around GBHs. More sensitive observations in the future at energies >250 keV will help answer questions regarding issues such as the nonthermal electron distribution, state transitions, and the connection to jets
Studies on plasma treatment and priming of seeds of bell pepper (Capsicum annuum L.)
The present investigation was carried out at Dr. Y.S. Parmar University of Horticulture and Forestry, Nauni, Solan during the year 2014 -2015 to study the “Effect of cold plasma treatment and priming on bell pepper (Capsicum annuum L. cultivar California Wonder) for seed germination and seedling vigour. The seeds were ex-posed to various durations of oxygen plasma treatment using glow discharge technique at FCIPT, Institute for Plas-ma Research, Gandhinagar, Gujarat, India. Seeds were pre-treated with power of 100 W for treatment durations of 0, 3, 6, 9, 12, 15 minutes for 0, 4, 8 and 12 month durations. The changes in surface morphology of plasma treated seeds were studied by Scanning Electron Microscopy (SEM) and Contact Angle Goniometer. Along with plasma treatment, seeds were also treated with standard priming method i.e osmoprimng for comparison. Results showed that plasma treatment alone as well as in combination with osmoprimng up to 6 minutes duration had positive effects on seed germination and seedling vigour. Germination and vigour indices significantly increased by 21.75% and 90.71% respectively. Characteristics of germination percentage, speed of germination, seedling vigour index-I & II, significantly increased by 13.92%, 1.39 cm, 0.38 mg, 322.07 respectively, compared with control. And it was found that immediately after plasma exposure the germination (84.41%) and vigour (228.50) was highest and it was reduced to (73.54%) and (174.27) after 12 months of storage. These results indicated that cold plasma treatment might promote the growth and modify the speed of germination i.e. higher speed of germination was observed in seeds exposed to plasma treat-ment for 6 minutes (59.82%), whereas, lowest germination speed (40.76%) was observed in untreated control
Development of an orthogonal-stripe CdZnTe gamma radiation imaging spectrometer
We report performance measurements of a sub-millimeter resolution CdZnTe strip detector developed as a prototype for astronomical instruments operating with good efficiency in the 30-300 keV photon energy range. The prototype is a 1.4 mm thick, 64×64 contact stripe CdZnTe array of 0.375 mm pitch in both dimensions. Pulse height spectra were recorded in orthogonal-stripe coincidence mode which demonstrate room-temperature energy resolution \u3c10 keV (FWHM) for 122 keV photons with a peak-to-valley ratio \u3e5:1. Good response is also demonstrated at higher energies using a coplanar grid readout configuration. Spatial resolution capabilities finer than the stripe pitch are demonstrated. We present the image of a 133Ba source viewed through a collimator slit produced by a 4×4 stripe detector segment. Charge signals from electron and hole collecting contacts are also discussed
A utilitarian antagonist: the zombie in popular video games
This article takes as its starting point the prevalence of the zombie in video games. I argue that, although the zombie games often superficially resemble filmic texts in their use of aesthetic and narrative, they must be understood, less as a set of conventions and thematic metaphors in the way that the zombie text has been read in film and television scholarship, and more as a utilisation of the zombie as a utilitarian antagonist that facilitates and permits the pleasures of violence and fantasy in video game play. Beginning with the Resident Evil and Left 4 Dead series of games I examine the way that games necessarily update the notion zombie as mass antagonist via the need to vary gameplay activity through different styles of adversary for players. At the same time I will demonstrate that, far from simply being the province of the survival horror genre, the zombie appears across an array of game forms, game cultures and game productions. The zombie highlights the participatory nature of game culture in the array of zombie 'mods' that users create to transform existing games into zombie based games, in particular in relation to titles such as the Call of Duty series. At the other end of the production spectrum the zombie features heavily in the little studied area of online flash games where the zombie can be found in a variety of game genres and forms. The zombie here often operates as a pastiche of popular zombie narratives in survival games (The Last Stand), parodic engagements with zombie conventions (Jetpacks and Zombies) or play with the notion of zombie pandemics (the Infectionator games). Here I situate the zombie game as a aesthetic genre that works to provide an easily understandable context for such interactive genres as survival horror, text adventures, shooting games, physics games and driving games, with the popularity of these enough to drive numerous dedicated hosting and link sites such as zombiegames.net. The pastiche element of these games extends into gamers social engagement with games. Online debates over the the appropriate actions or preparation for a zombie holocaust are commonplace on the internet in such spaces as Zombieresearch.net. Whilst many of these sites feature decidedly tongue in cheek engagement with the notion of the zombie apocalypse, the users of fora for games like Left 4 Dead and Dead Island tend to debate this directly in the terms of the games themselves, discussing their relative merits or realism. Some of these games also highlight the specific pleasures of identifying the zombie as protagonist of sorts. In discussing this I will return to online gaming and the Left 4 Dead games in which players may compete online as part of the zombie horde. Such games raise major questions for the issues of identification and immersion that are said to be at the centre of the game experience. I will also explore the parodic pleasures of many flash games that situate the player in the role of spreading zombie infections. Throughout this article I aim to demonstrate that the zombie in game culture is less a cultural metaphor than a combination of utilitarian antagonist and a persistent aesthetic; a means of providing style or pleasure to many games that relies on the intertextual and flexible nature of the zombie as popular cultural phenomenon
Using airborne LiDAR Survey to explore historic-era archaeological landscapes of Montserrat in the eastern Caribbean
This article describes what appears to be the first archaeological application of airborne LiDAR survey to historic-era landscapes in the Caribbean archipelago, on the island of Montserrat. LiDAR is proving invaluable in extending the reach of traditional pedestrian survey into less favorable areas, such as those covered by dense neotropical forest and by ashfall from the past two decades of active eruptions by the Soufrière Hills volcano, and to sites in localities that are inaccessible on account of volcanic dangers. Emphasis is placed on two aspects of the research: first, the importance of ongoing, real-time interaction between the LiDAR analyst and the archaeological team in the field; and second, the advantages of exploiting the full potential of the three-dimensional LiDAR point cloud data for purposes of the visualization of archaeological sites and features
Large-area submillimeter resolution CdZnTe strip detector for astronomy
We report the first performance measurements of a sub-millimeter CdZnTe strip detector developed as a prototype for space-borne astronomical instruments. Strip detector arrays can be used to provide two-dimensional position resolution with fewer electronic channels than pixellated arrays. Arrays of this type and other candidate technologies are under investigation for the position-sensitive backplane detector for a coded-aperture telescope operating in the range of 30 - 300 keV. The prototype is a 1.4 mm thick, 64 multiplied by 64 stripe CdZnTe array of 0.375 mm pitch in both dimensions, approximately one square inch of sensitive area. Pulse height spectra in both single and orthogonal stripe coincidence mode were recorded at several energies. The results are compared to slab- and pixel-geometry detector spectra. The room-temperature energy resolution is less than 10 keV (FWHM) for 122 keV photons with a peak-to-valley ratio greater than 5:1. The response to photons with energies up to 662 keV appears to be considerably improved relative to that of previously reported slab and pixel detectors. We also show that strip detectors can yield spatial and energy resolutions similar to those of pixellated arrays with the same dimensions. Electrostatic effects on the pulse heights, read-out circuit complexity, and issues related to design of space borne instruments are also discussed
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