Summary
Bread wheat (Triticum aestivum L.) is cultivated on more land than any other crop and produces a fifth of the calories consumed by humans. Wheat endosperm is rich in starch yet contains low ...concentrations of dietary iron (Fe) and zinc (Zn). Biofortification is a micronutrient intervention aimed at increasing the density and bioavailability of essential vitamins and minerals in staple crops; Fe biofortification of wheat has proved challenging. In this study we employed constitutive expression (CE) of the rice (Oryza sativa L.) nicotianamine synthase 2 (OsNAS2) gene in bread wheat to up‐regulate biosynthesis of two low molecular weight metal chelators – nicotianamine (NA) and 2′‐deoxymugineic acid (DMA) – that play key roles in metal transport and nutrition. The CE‐OsNAS2 plants accumulated higher concentrations of grain Fe, Zn, NA and DMA and synchrotron X‐ray fluorescence microscopy (XFM) revealed enhanced localization of Fe and Zn in endosperm and crease tissues, respectively. Iron bioavailability was increased in white flour milled from field‐grown CE‐OsNAS2 grain and positively correlated with NA and DMA concentrations.
SUMMARY
Conventional breeding efforts for iron (Fe) and zinc (Zn) biofortification of bread wheat (Triticum aestivum L.) have been hindered by a lack of genetic variation for these traits and a ...negative correlation between grain Fe and Zn concentrations and yield. We have employed genetic engineering to constitutively express (CE) the rice (Oryza sativa) nicotianamine synthase 2 (OsNAS2) gene and upregulate biosynthesis of two metal chelators – nicotianamine (NA) and 2′‐deoxymugineic acid (DMA) – in bread wheat, resulting in increased Fe and Zn concentrations in wholemeal and white flour. Here we describe multi‐location confined field trial (CFT) evaluation of a low‐copy transgenic CE‐OsNAS2 wheat event (CE‐1) over 3 years and demonstrate higher concentrations of NA, DMA, Fe, and Zn in CE‐1 wholemeal flour, white flour, and white bread and higher Fe bioavailability in CE‐1 white flour relative to a null segregant (NS) control. Multi‐environment models of agronomic and grain nutrition traits revealed a negative correlation between grain yield and grain Fe, Zn, and total protein concentrations, yet no correlation between grain yield and grain NA and DMA concentrations. White flour Fe bioavailability was positively correlated with white flour NA concentration, suggesting that NA‐chelated Fe should be targeted in wheat Fe biofortification efforts.
Significance Statement
Nicotianamine (NA) and 2′‐deoxymugineic acid (DMA) are important chelators of iron (Fe) and zinc (Zn) in graminaceous plants. Field evaluation of biofortified wheat (Triticum aestivum) containing higher concentrations of NA, DMA, Fe, and Zn in wholemeal flour, white flour, and white bread demonstrated that grain NA and DMA concentrations do not correlate with yield and highlighted NA‐chelated Fe as a promising target for wheat biofortification programs.
Custom ultrasonic instruments have been developed for simultaneous monitoring of binary gas mixture and flow in the ATLAS Inner Detector. Sound transit times are measured in opposite directions in ...flowing gas. Flow rate and sound velocity are respectively calculated from their difference and average. Gas composition is evaluated in real-time by comparison with a sound velocity/composition database, based on the direct dependence of sound velocity on component concentrations in a mixture at known temperature and pressure. Five devices are integrated into the ATLAS Detector Control System. Three instruments monitor coolant leaks into N2 envelopes of the silicon microstrip and Pixel detectors. Resolutions better than ±2×10−5 and ±2×10−4 are seen for C3F8 and CO2 leak concentrations in N2 respectively. A fourth instrument detects sub-percent levels of air ingress into the C3F8 condenser of the new thermosiphon coolant recirculator. Following extensive studies a fifth instrument was built as an angled sound path flowmeter to measure the high returning C3F8 vapour flux (∼1.2kgs−1). A precision of <2.3% FS for flows up to 10ms−1 was demonstrated. These instruments have many potential applications where continuous binary gas composition measurement is required, including hydrocarbon and anaesthetic gas mixtures.
The silicon tracker of the ATLAS experiment at CERN Large Hadron Collider will operate around –15°C to minimize the effects of radiation damage. The present cooling system is based on a conventional ...evaporative circuit, removing around 60 kW of heat dissipated by the silicon sensors and their local electronics. The compressors in the present circuit have proved less reliable than originally hoped, and will be replaced with a thermosiphon. The working principle of the thermosiphon uses gravity to circulate the coolant without any mechanical components (compressors or pumps) in the primary coolant circuit. The fluorocarbon coolant will be condensed at a temperature and pressure lower than those in the on-detector evaporators, but at a higher altitude, taking advantage of the 92 m height difference between the underground experiment and the services located on the surface. An extensive campaign of tests, detailed in this paper, was performed using two small-scale thermosiphon systems. These tests confirmed the design specifications of the full-scale plant and demonstrated operation over the temperature range required for ATLAS. During the testing phase the system has demonstrated unattended long-term stable running over a period of several weeks. The commissioning of the full scale thermosiphon is ongoing, with full operation planned for late 2015.
Human cytomegalovirus (hCMV), a herpesvirus, infects up to 70% of the general population in the United States and can cause morbidity and mortality in immunosuppressed individuals (organ-transplant ...recipients and AIDS patients) and congenitally infected newborns. hCMV protease is essential for the production of mature infectious virions, as it performs proteolytic processing near the carboxy terminus (M-site) of the viral assembly protein precursor. hCMV protease is a serine protease, although it has little homology to other clans of serine proteases. Here we report the crystal structure of hCMV protease at 2.0 angstroms resolution, and show that it possesses a new polypeptide backbone fold. Ser 132 and His 63 are found in close proximity in the active site, confirming earlier biochemical and mutagenesis studies. The structure suggests that the third member of the triad is probably His 157. A dimer of the protease with an extensive interface is found in the crystal structure. This structure information will help in the design and optimization of inhibitors against herpesvirus proteases.
Performance of the CLAS12 Silicon Vertex Tracker modules Antonioli, M.A.; Boiarinov, S.; Bonneau, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2013, Letnik:
732
Journal Article
Recenzirano
Odprti dostop
For the 12GeV upgrade, the CLAS12 experiment has designed a Silicon Vertex Tracker (SVT) using single sided microstrip sensors fabricated by Hamamatsu. The sensors have graded angle design to ...minimize dead areas and a readout pitch of 156μm, with intermediate strip. Double sided SVT module hosts three daisy-chained sensors on each side with a full strip length of 33cm. There are 512 channels per module read out by four Fermilab Silicon Strip Readout (FSSR2) chips featuring data driven architecture, mounted on a rigid-flex hybrid. Modules are assembled on the barrel using unique cantilevered geometry to minimize the amount of material in the tracking volume. Design and performance of the SVT modules are presented, focusing on results of electrical measurements.
•A Silicon Vertex Tracker has been designed for the central tracker of the CLAS12 experiment.•Using cantilevered module geometry allows minimizing amount of material in the tracking volume.•A dedicated Hybrid Flex Circuit Board has been developed to read out double sided module.•Module performance meets design goals of the CLAS12 Central Tracker.
Triangular Bezier patches are an important tool for defining smooth surfaces over arbitrary triangular meshes. The previously introduced 4-split method interpolates the vertices of a 2-manifold ...triangle mesh by a set of tangent plane continuous triangular Bezier patches of degree five. The resulting surface has an explicit closed form representation and is defined locally. In this paper, we introduce a new method for visually smooth interpolation of arbitrary triangle meshes based on a regular 4-split of the domain triangles. Ensuring tangent plane continuity of the surface is not enough for producing an overall fair shape. Interpolation of irregular control-polygons, be that in 1D or in 2D, often yields unwanted undulations. Note that this undulation problem is not particular to parametric interpolation, but also occurs with interpolatory subdivision surfaces. Our new method avoids unwanted undulations by relaxing the constraint of the first derivatives at the input mesh vertices: The tangent directions of the boundary curves at the mesh vertices are now completely free. Irregular triangulations can be handled much better in the sense that unwanted undulations due to flat triangles in the mesh are now avoided.
We describe a combined ultrasonic instrument for continuous gas flow measurement and simultaneous real-time binary gas mixture analysis. In the instrument, sound bursts are transmitted in opposite ...directions, which may be aligned with the gas flow path or at an angle to it, the latter configuration being the best adapted to high flow rates. The combined flow measurement and mixture analysis algorithm exploits the phenomenon whereby the sound velocity in a binary gas mixture at known temperature and pressure is a unique function of the molar concentration of the two components. The instrument is central to a possible upgrade to the present ATLAS silicon tracker cooling system in which octafluoropropane (C F ) evaporative cooling fluid would be replaced by a blend containing up to 25% hexafluoroethane (C 2 F 6 ). The instrument has been developed in two geometries following computational fluid dynamics studies of various mechanical layouts. An instrument with 45 crossing angle has been installed for commissioning in the ATLAS silicon tracker cooling system. It can be used in gas flows up to 20 000 l.min -1 and has demonstrated a flow resolution of 2.3% of full scale for linear flow velocities up to 10 m.s in preliminary studies with air. Other instruments are currently used to detect low levels of C 2 F 8 vapor leaking into the N 2 environmental gas surrounding the ATLAS silicon tracker. A long-duration continuous study of more than a year has demonstrated a sensitivity to mixture variation of better than 5.10 -5 .
Image Guided Radiation Therapy (IGRT) is one of the most efficient ways to treat prostate cancer. It is well‐known that Electronic Portal Images (EPI) acquired prior to the radiation therapy are of ...poor quality due to the low radiation dose. Several image parameters need to be manually adjusted in order to be able to visualize and localize the fiducial markers (FMs) seeds at the beginning of each day of treatment. This localization process is essential for the proper alignment of the patient. In this paper, we propose a novel technique for automatic image enhancement. There are many challenges involved in the automation of the image enhancement for FM seed detection. An automated enhancement algorithm is image and noise dependant. The level of noise in an input image and global image properties such as average contrast and intensity vary significantly between different patients and even for the same patient between different image acquisition sessions. Moreover, the small size of the targets (the FM seeds) makes it very difficult to distinguish them from noise, and hence to enhance them. Our approach addresses these challenges by using a contrast enhancement scheme based on properties of the human visual system (HVS). The rationale behind considering this approach lies in the ability of the HVS to adapt to detect objects of small size under low contrast and noise conditions. Our main contribution lies in the automatic set‐up of the parameters based upon a maxima search over a contrast metric.
PDF
