X-Ray Microanalysis of Hollow Heart Potatoes

Electron microprobe and X-ray fluorescence techniques were used to study elemental gradients associated with the physiological disorder hollow heart i n potato tubers. Gradients were found along the length and across the width of mature tubers. These were not rela ted to the disorder, however . Tubers with advanced symptoms of the disorder had elemental levels and gradients similar to those in healthy, control tubers. The results suggest that if the disorder is initially caused by an elemental deficiency, as has sometimes been proposed , the deficiency is temporary and no longer exists in mature tubers with advanced hollow heart. Radial gradients were associated rnd inly with two contrasting tissues . the centra 1 pith and the surrounding perimedullary zone. Tissue differences are critical in microprobe studies involving small samples Microprobe studies of developing tubers containing incipient stages of hollow heart. employing strip samples restricted to the central pith where the disorder originates and taken so as to traverse the small lesions, showed a dramatic increase in Mg in lesion areas. It is suggested that a nutrient imbalance may trigger the onset of the cell necrosis that characterizes the initiation of hollow heart in potato . A localized Mg toxicity or Ca deficiency due to high Mg:Ca ratio is implicated

Evaluation of be-38 percent al alloy final report, 27 jun. 1964 - 28 feb. 1965

Mechanical properties, microstructural features, and general metallurgical quality of beryllium- aluminum allo

Comparison of free tropospheric western Pacific air mass classification schemes for the PEM-West A experiment

During September/October 1991, NASA's Global Tropospheric Experiment (GTE) conducted an airborne field measurement program (PEM-West A) in the troposphere over the western Pacific Ocean. In this paper we describe and use the relative abundance of the combustion products C2H2 and CO to classify air masses encountered during PEM-West A based on the degree that these tracers were processed by the combined effects of photochemical reactions and dynamical mixing (termed the degree of atmospheric processing). A large number of trace compounds (e.g., C2H6, C3H8, C6H6, NOy, and O3) are found to be well correlated with the degree of atmospheric processing that is reflected by changes in the ratio of C2H2/CO over the range of values from ∼0.3 to 2.0 (parts per trillion volume) C2H2/ (parts per billion volume) CO. This C2H2/CO-based classification scheme is compared to model simulations and to two independent classification schemes based on air mass back-trajectory analyses and lidar profiles of O3 and aerosols. In general, these schemes agree well, and in combination they suggest that the functional dependence that other observed species exhibit with respect to the C2H2/CO atmospheric processing scale can be used to study the origin, sources, and sinks of trace species and to derive several important findings. First, the degree of atmospheric processing is found to be dominated by dilution associated with atmospheric mixing, which is found to primarily occur through the vertical mixing of relatively recent emissions of surface layer trace species. Photochemical reactions play their major role by influencing the background concentrations of trace species that are entrained during the mixing (i.e., dilution) process. Second, a significant noncontinental source(s) of NO (and NOx) in the free troposphere is evident. In particular, the enhanced NO mixing ratios that were observed in convected air masses are attributed to either emissions from lightning or the rapid recycling of NOy compounds. Third, nonsoluble trace species emitted in the continental boundary layer, such as CO and hydrocarbons, are vertically transported to the upper troposphere as efficiently as they are to the midtroposphere. In addition, the mixing ratios of CO and hydrocarbons in the upper troposphere over the western Pacific may reflect a significant contribution from northern hemisphere land areas other than Asia. Finally, we believe that these results can be valuable for the quantitative evaluation of the vertical transport processes that are usually parameterized in models. Copyright 1996 by the American Geophysical Union

Genetically engineered bananas resistant to Xanthomonas wilt disease and nematodes

Banana is an important staple food crop feeding more than 100 million Africans, but is subject to severe productivity constraints due to a range of pests and diseases. Banana Xanthomonas wilt caused by Xanthomonas campestris pv. musacearum is capable of entirely destroying a plantation while nematodes can cause losses up to 50% and increase susceptibility to other pests and diseases. Development of improved varieties of banana is fundamental in order to tackle these challenges. However, the sterile nature of the crop and the lack of resistance in Musa germplasm make improvement by traditional breeding techniques either impossible or extremely slow. Recent developments using genetic engineering have begun to address these problems. Transgenic banana expressing sweet pepper Hrap and Pflp genes have demonstrated complete resistance against X. campestris pv. musacearum in the field. Transgenic plantains expressing a cysteine proteinase inhibitors and/or synthetic peptide showed enhanced resistance to a mixed species population of nematodes in the field. Here, we review the genetic engineering technologies which have potential to improve agriculture and food security in Africa

Molecular Dynamics Simulation of Sympathetic Crystallization of Molecular Ions

It is shown that the translational degrees of freedom of a large variety of molecules, from light diatomic to heavy organic ones, can be cooled sympathetically and brought to rest (crystallized) in a linear Paul trap. The method relies on endowing the molecules with an appropriate positive charge, storage in a linear radiofrequency trap, and sympathetic cooling. Two well--known atomic coolant species, ${}^9{\hbox{Be}}^+$ and ${}^{137}{\hbox{Ba}}^+$, are sufficient for cooling the molecular mass range from 2 to 20,000 amu. The large molecular charge required for simultaneous trapping of heavy molecules and of the coolant ions can easily be produced using electrospray ionization. Crystallized molecular ions offer vast opportunities for novel studies.Comment: Accepted for publication in Phys. Rev.

Quasi-Quantum Groups, Knots, Three-Manifolds, and Topological Field Theory

We show how to construct, starting from a quasi-Hopf algebra, or quasi-quantum group, invariants of knots and links. In some cases, these invariants give rise to invariants of the three-manifolds obtained by surgery along these links. This happens for a finite-dimensional quasi-quantum group, whose definition involves a finite group $G$, and a 3-cocycle \om, which was first studied by Dijkgraaf, Pasquier and Roche. We treat this example in more detail, and argue that in this case the invariants agree with the partition function of the topological field theory of Dijkgraaf and Witten depending on the same data G, \,\om.Comment: 30 page

The association between peripheral inflammation, brain glutamate and antipsychotic response in Schizophrenia:Data from the STRATA collaboration

Glutamate and increased inflammation have been separately implicated in the pathophysiology of schizophrenia and the extent of clinical response to antipsychotic treatment. Despite the mechanistic links between pro-inflammatory and glutamatergic pathways, the relationships between peripheral inflammatory markers and brain glutamate in schizophrenia have not yet been investigated. In this study, we tested the hypothesis that peripheral levels of pro-inflammatory cytokines would be positively associated with brain glutamate levels in schizophrenia. Secondary analyses determined whether this relationship differed according to antipsychotic treatment response. The sample consisted of 79 patients with schizophrenia, of whom 40 were rated as antipsychotic responders and 39 as antipsychotic non-responders. Brain glutamate levels were assessed in the anterior cingulate cortex (ACC) and caudate using proton magnetic resonance spectroscopy (1H-MRS) and blood samples were collected for cytokine assay on the same study visit (IL-6, IL-8, IL-10, TNF- α and IFN-γ). Across the whole patient sample, there was a positive relationship between interferon-gamma (IFN-γ) and caudate glutamate levels (r = 0.31, p = 0.02). In the antipsychotic non-responsive group only, there was a positive relationship between interleukin-8 (IL-8) and caudate glutamate (r = 0.46, p = 0.01). These findings provide evidence to link specific peripheral inflammatory markers and caudate glutamate in schizophrenia and may suggest that this relationship is most marked in patients who show a poor response to antipsychotic treatment