Research Notes : United States : Necrotic root mutants in a genetically unstable line of soybean

Mutations for necrotic roots were identified in an experiment designed to recover new mutations in the Asgrow Mutable line as evidence for transposition of a mobile genetic element (Groose and Palmer, 1987). Each of three independent mutations for necrotic roots was discovered in a different F11 family, each of which had descended from a different F9 plant of the Asgrow Mutable line. Seedlings of 1 936 F11 families were pulled from the sandbench at the second trifoliolate leaf stage and roots were examined for nonfluorescent root mutations

Research Notes : United States : Chlorophyll-deficient mutants in a genetically unstable line of soybean

Mutations for chlorophyll deficiency were identified in an experiment designed to -recover new mutations in the Asgrow Mutable line as evidence for transposition of a mobile genetic element. A detailed protocol for the experiment is presented in the preceding research note (Groose and Palmer, 1987). Each of three independent mutations that are described below was discovered in a sandbench test of a different F11 family, each of which had descended from a different F9 plant of the Asgrow Mutable line

Design and development of a low temperature, inductance based high frequency ac susceptometer

We report on the development of an induction based low temperature high frequency ac susceptometer capable of measuring at frequencies up to 3.5 MHz and at temperatures between 2 K and 300 K. Careful balancing of the detection coils and calibration have allowed a sample magnetic moment resolution of $5\times10^{-10} Am^2$ at 1 MHz. We will discuss the design and characterization of the susceptometer, and explain the calibration process. We also include some example measurements on the spin ice material CdEr$_2$S$_4$ and iron oxide based nanoparticles to illustrate functionality

Measurements of the Proton-Neutron Correlation in Deuteron Breakup at 260 MeV

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Sweden: Political Developments and Data in 2019

OA via Wiley Jisc agreementPeer reviewedPublisher PD

Nucleon-induced fission cross-sections of tantalum and separated tungsten isotopes and "compound nucleus" effect in intermediate energy region

Neutron- and proton-induced fission cross-sections of separated isotopes of tungsten (182W, 183W, 184W, and 186W) and 181Ta relative to 209Bi have been measured in the incident nucleon energy region 50 - 200 MeV using fission chambers based on thin-film breakdown counters (TFBC) using quasi-monoenergetic neutrons from the 7Li(p,n) reaction and at the proton beams of The Svedberg Laboratory (TSL), Uppsala University (Uppsala, Sweden). The results are compared with predictions by the CEM03.01 event generator, as well as with the recent data for nuclei in the lead-bismuth region. The effect of "compound nucleus" in the intermediate energy region is discussed, displaying in exponential dependence of nucleon-induced fission cross-sections on the parameter Z^2/A of the composite system (projectile+target nucleus), and in other characteristics of the fission process for which parameter Z^2/A plays a role similar to the one of the usual liquid-drop parameter Z^2/A of compound nuclei.Comment: 4 pages, 3 figures, 2 tables, only pdf file, to be published in Proc. Int. Conf. on Nucl. Data for Sci. and Technology (ND2007), Nice, France, April 22-27, 200

Synergistic and antagonistic effects of land use and non‐native species on community responses to climate change

Climate change, land‐use change and introductions of non‐native species are key determinants of biodiversity change worldwide. However, the extent to which anthropogenic drivers of environmental change interact to affect biological communities is largely unknown, especially over longer time periods. Here, we show that plant community composition in 996 Swedish landscapes has consistently shifted to reflect the warmer and wetter climate that the region has experienced during the second half of the 20th century. Using community climatic indices, which reflect the average climatic associations of the species within each landscape at each time period, we found that species compositions in 74% of landscapes now have a higher representation of warm‐associated species than they did previously, while 84% of landscapes now host more species associated with higher levels of precipitation. In addition to a warmer and wetter climate, there have also been large shifts in land use across the region, while the fraction of non‐native species has increased in the majority of landscapes. Climatic warming at the landscape level appeared to favour the colonization of warm‐associated species, while also potentially driving losses in cool‐associated species. However, the resulting increases in community thermal means were apparently buffered by landscape simplification (reduction in habitat heterogeneity within landscapes) in the form of increased forest cover. Increases in non‐native species, which generally originate from warmer climates than Sweden, were a strong driver of community‐level warming. In terms of precipitation, both landscape simplification and increases in non‐natives appeared to favour species associated with drier climatic conditions, to some extent counteracting the climate‐driven shift towards wetter communities. Anthropogenic drivers can act both synergistically and antagonistically to determine trajectories of change in biological communities over time. Therefore, it is important to consider multiple drivers of global change when trying to understand, manage and predict biodiversity in the future

Grafting Neural Stem and Progenitor Cells Into the Hippocampus of Juvenile, Irradiated Mice Normalizes Behavior Deficits

The pool of neural stem and progenitor cells (NSPCs) in the dentate gyrus of the hippocampus is reduced by ionizing radiation. This explains, at least partly, the learning deficits observed in patients after radiotherapy, particularly in pediatric cases. An 8 Gy single irradiation dose was delivered to the whole brains of postnatal day 9 (P9) C57BL/6 mice, and BrdU-labeled, syngeneic NSPCs (1.0 × 105 cells/injection) were grafted into each hippocampus on P21. Three months later, behavior tests were performed. Irradiation impaired novelty-induced exploration, place learning, reversal learning, and sugar preference, and it altered the movement pattern. Grafting of NSPCs ameliorated or even normalized the observed deficits. Less than 4% of grafted cells survived and were found in the dentate gyrus 5 months later. The irradiation-induced loss of endogenous, undifferentiated NSPCs in the dentate gyrus was completely restored by grafted NSPCs in the dorsal, but not the ventral, blade. The grafted NSPCs did not exert appreciable effects on the endogenous NSPCs; however, more than half of the grafted NSPCs differentiated. These results point to novel strategies aimed at ameliorating the debilitating late effects of cranial radiotherapy, particularly in children

Nucleon-induced reactions at intermediate energies: New data at 96 MeV and theoretical status

Double-differential cross sections for light charged particle production (up to A=4) were measured in 96 MeV neutron-induced reactions, at TSL laboratory cyclotron in Uppsala (Sweden). Measurements for three targets, Fe, Pb, and U, were performed using two independent devices, SCANDAL and MEDLEY. The data were recorded with low energy thresholds and for a wide angular range (20-160 degrees). The normalization procedure used to extract the cross sections is based on the np elastic scattering reaction that we measured and for which we present experimental results. A good control of the systematic uncertainties affecting the results is achieved. Calculations using the exciton model are reported. Two different theoretical approches proposed to improve its predictive power regarding the complex particle emission are tested. The capabilities of each approach is illustrated by comparison with the 96 MeV data that we measured, and with other experimental results available in the literature.Comment: 21 pages, 28 figure