Back to Earth: Molecular Approaches to Microbial Ecology Must Consider Soil Morphology and Physicochemical Properties

This project studied the influence of different long-term agricultural management regimes on soil microbial communities, and compared survival strategies of individual prokaryotic OTUs in diverse soils subjected to long-term incubation. Together these would show whether alterations to microbial communities affect rates of soil carbon cycling. Agricultural soils were sampled at arbitrary depths above and below the plow layer, and relative abundances of microbes were measured using high-throughput sequencing. `Activity' (rRNA:rDNA) ratios were calculated for individual OTUs identified by high-throughput sequencing of tropical rainforest and temperate cornfield soils after incubation for one year with differing water and carbon availabilities. It was found that depth controls microbial communities to a greater degree than agricultural management, and that the characterization of microbial trophic strategies might be complicated by the often-ignored DNA preservation potential of soil. The study highlights the need for holistic approaches to testing hypotheses in modern microbial ecology

Dysregulated Erythroid Mg2+ Efflux in Type 2 Diabetes

CEECIND/01053/2017 UIDB/04647/2020 UIDP/04647/2020Hyperglycemia is associated with decreased Mg2+ content in red blood cells (RBC), but mechanisms remain unclear. We characterized the regulation of Mg2+ efflux by glucose in ex vivo human RBC. We observed that hemoglobin A1C (HbA1C) values correlated with Na+-dependent Mg2+ efflux (Na+/Mg2+ exchange) and inversely correlated with cellular Mg content. Treatment of cells with 50 mM D-glucose, but not with sorbitol, lowered total cellular Mg (2.2 ± 0.1 to 2.0 ± 0.1 mM, p < 0.01) and enhanced Na+/Mg2+ exchange activity [0.60 ± 0.09 to 1.12 ± 0.09 mmol/1013 cell × h (flux units, FU), p < 0.05]. In contrast, incubation with selective Src family kinase inhibitors PP2 or SU6656 reduced glucose-stimulated exchange activation (p < 0.01). Na+/Mg2+ exchange activity was also higher in RBC from individuals with type 2 diabetes (T2D, 1.19 ± 0.13 FU) than from non-diabetic individuals (0.58 ± 0.05 FU, p < 0.01). Increased Na+/Mg2+ exchange activity in RBC from T2D subjects was associated with lower intracellular Mg content. Similarly increased exchange activity was evident in RBC from the diabetic db/db mouse model as compared to its non-diabetic control (p < 0.03). Extracellular exposure of intact RBC from T2D subjects to recombinant peptidyl-N-glycosidase F (PNGase F) reduced Na+/Mg2+ exchange activity from 0.98 ± 0.14 to 0.59 ± 0.13 FU (p < 0.05) and increased baseline intracellular Mg content (1.8 ± 0.1 mM) to normal values (2.1 ± 0.1 mM, p < 0.05). These data suggest that the reduced RBC Mg content of T2D RBC reflects enhanced RBC Na+/Mg2+ exchange subject to regulation by Src family kinases and by the N-glycosylation state of one or more membrane proteins. The data extend our understanding of dysregulated RBC Mg2+ homeostasis in T2D.publishersversionpublishe

Hyperspectral Mapping of the Invasive Species Pepperweed and the Development of a Habitat Suitability Model

Mapping and predicting the spatial distribution of invasive plant species is central to habitat management, however difficult to implement at landscape and regional scales. Remote sensing techniques can reduce the impact field campaigns have on these ecologically sensitive areas and can provide a regional and multi-temporal view of invasive species spread. Invasive perennial pepperweed (Lepidium latifolium) is now widespread in fragmented estuaries of the South San Francisco Bay, and is shown to degrade native vegetation in estuaries and adjacent habitats, thereby reducing forage and shelter for wildlife. The purpose of this study is to map the present distribution of pepperweed in estuarine areas of the South San Francisco Bay Salt Pond Restoration Project (Alviso, CA), and create a habitat suitability model to predict future spread. Pepperweed reflectance data were collected in-situ with a GER 1500 spectroradiometer along with 88 corresponding pepperweed presence and absence points used for building the statistical models. The spectral angle mapper (SAM) classification algorithm was used to distinguish the reflectance spectrum of pepperweed and map its distribution using an image from EO-1 Hyperion. To map pepperweed, we performed a supervised classification on an ASTER image with a resulting classification accuracy of 71.8%. We generated a weighted overlay analysis model within a geographic information system (GIS) framework to predict areas in the study site most susceptible to pepperweed colonization. Variables for the model included propensity for disturbance, status of pond restoration, proximity to water channels, and terrain curvature. A Generalized Additive Model (GAM) was also used to generate a probability map and investigate the statistical probability that each variable contributed to predict pepperweed spread. Results from the GAM revealed distance to channels, distance to ponds and curvature were statistically significant (p < 0.01) in determining the locations of suitable pepperweed habitats

Probing Interfacial Processes of Lithium Ion Batteries

In the last decade, lithium ion batteries held a major role in the path towards personal electronics due to being lightweight and providing a high energy density. However, several problems have been identified with lithium ion batteries. Due to inherent instability, lithium ion batteries are known to have issues with safety and capacity loss. Our goal is to advance the understanding of the electrochemical processes, specifically the interfacial processes at the anode, to continue their advancement in our electronic age. At the interface of the electrolyte and anode, during the first several charging and discharging cycles, appears a protective layer by interaction of decomposed electrolyte at the electrode surface. This protective layer, termed the solid electrolyte interphase, is of particular importance as it increases the stability, impeding dendrite growth, and ultimately leading to improved capacity and safety. Our electrolyte is a lithium salt (LiClO4) with ethylene carbonate (EC) in a tetrahydrofuran (THF) solvent, leading, primarily, to one of the main SEI contributors, lithium ethylene dicarbonate (LiEDC). By spectroscopically probing the interface with sumfrequency generation and simultaneously scanning with cyclic voltammetry, we are able to see the SEI contribution formation in real time.Ope

BeSAT: Behavioral SAT-based Attack on Cyclic Logic Encryption

Cyclic logic encryption is newly proposed in the area of hardware security. It introduces feedback cycles into the circuit to defeat existing logic decryption techniques. To ensure that the circuit is acyclic under the correct key, CycSAT is developed to add the acyclic condition as a CNF formula to the SAT-based attack. However, we found that it is impossible to capture all cycles in any graph with any set of feedback signals as done in the CycSAT algorithm. In this paper, we propose a behavioral SAT-based attack called BeSAT. BeSAT observes the behavior of the encrypted circuit on top of the structural analysis, so the stateful and oscillatory keys missed by CycSAT can still be blocked. The experimental results show that BeSAT successfully overcomes the drawback of CycSAT

Classical, non-linear, internal dynamics of large, isolated, vibrationally excited molecules

This work reports numerical experiments intended to clarify the internal equilibration process in large molecules, following vibrational excitation. A model of amorphous and oxygenated hydrocarbon macromolecule (about 500 atoms)--simulating interstellar dust-- is built up by means of a chemical simulation code. Its structure is optimized, and its normal modes determined. About 4.5 eV of potential energy is then deposited locally by perturbing one of the C-H peripheral bonds, thus simulating the capture of a free H atom by a dangling C bond. The ensuing relaxation of the system is followed for up to 300 ps, using a molecular mechanics code. When steady state is reached, spectra and time correlation functions of kinetic energy and bond length fluctuations indicate that most normal modes have been activated, but the motion remains quasi-periodic or regular. By contrast, when the molecule is violently excited or embedded in a thermal bath (modelled by Langevin dynamics), the same markers clearly depict chaotic motions. Thus it appears that even such a large system of oscillators is unable to provide the equivalent of a thermal bath to any one of these, unless there are strong resonances between some of them. In general, therefore, an energy of a few eV's deposited in an isolated molecule will not be immediately thermalized. This conclusion is of consequence for the interpretation of astronomical UIB spectra. Key Words:IS dust--UIBs--Excitation, relaxation processes.Comment: 19 pages, 9 figures, J. of Phys. B 2002, vol 35(17