The Electron Transport Through Strongly Coupled Double Quantum Dots : Effect of Spin Exchange Interaction

We introduce  model calculation for the electron transport through a system consists of two serially coupled quantum dots, embedded between two nonmagnetic leads (source and drain). In our treatment, the time independent Anderson-Newns Hamiltonian model is considered as a basis to study the system dynamics and then to derive spin-dependent analytical formula to calculate the occupation numbers of the quantum dots energy levels, the corresponding quantum dots energy levels and the molecular virtual energy levels, as a function of bias voltage. These relations are solved self-consistently, which are all employed to calculate the tunneling current considering the strong coupling regime. The differential conductance is calculated numerically by using finite differences method. And as the efficiency of electron transport through coupled quantum dots depends on the system parameters, the effective exchange energy is highlighted and studied in details and the role of this parameter in the tunneling current and the differential conductance calculations is presented. Our treatment is utilized to study the following The role of the spin exchange interaction in determining the type of  interaction (if it is attractive or repulsive) between the quantum dots...

ACHILLES Reading Guide 2: A deeper understanding of deterioration of engineered soils.

The engineering properties (e.g. strength,deformability, permeability) of the soils andcompacted fills that form the foundations forour infrastructure are known to change whenstresses are applied. These stresses can takethe form of increased traffic loading on aroad or rail line, or can be produced by thematerial shrinking and swelling as thematerial dries out in summer and becomessaturated in winter months. Whilst thesedrivers of deterioration are known [1,2] themechanisms through which the deteriorationoccurs is less well understood. To predicthow our infrastructure may deteriorate in thefuture it is important to understand theseprocesses. One of the aims of the ACHILLESteam has been to develop an improvedunderstanding of engineered soildeterioration at the material scale so we candetermine the magnitude of changes in soilproperties, estimate how long this processwill take and identify efficient means ofarresting this deterioration

Reproductive performance of native and imported dairy cows in the Tadla region (Morocco)

Parmi les performances de reproduction des vaches laitières dans la région du Tadla (Maroc) sur une période de 4 années, l’âge à la première insémination artificielle (IA) a été de 573,4 ± 35,6 jours et à l’âge au premier vêlage de 853,8 ± 103,5 jours, l’intervalle vêlage-1ère IA de 75,5 ± 35,6 jours. Celui-ci a été plus court chez les femelles importées que chez les natives. La race Montbéliarde a été inséminée plus tôt que la race Prim’Holstein. Le taux de réussite en 1ère IA a été de 53,2% avec de larges variations inter-annuelles et inter-élevages. Les Prim’holstein ont été mieux fécondées que les autres races. 18,2% des vaches ont nécessité 3 IA ou plus et l’indice coïtal a été de 1,8 ±1,3. La campagne, l’élevage et la race ont affecté significativement le taux de femelles ayant nécessité 3 IA ou plus. La race Prim’holstein française a manifesté un taux inférieur à celui de la race Prim’holstein canadienne. L’intervalle vêlage - insémination fécondante a été de 119,2 ± 83,8 jours. Ce paramètre a varié très significativement selon l’année, l’élevage, la race et le numéro de lactation. La race Montbéliarde a présenté undélai moyen de fécondation plus court que la race Prim’Holstein Canadienne

Cooperative Binding

Molecular binding is an interaction between molecules that results in a stable association between those molecules. Cooperative binding occurs if the number of binding sites of a macromolecule that are occupied by a specific type of ligand is a nonlinear function of this ligand’s concentration. This can be due, for instance, to an affinity for the ligand that depends on the amount of ligand bound. Cooperativity can be positive (supralinear) or negative (infralinear). Cooperative binding is most often observed in proteins, but nucleic acids can also exhibit cooperative binding, for instance of transcription factors. Cooperative binding has been shown to be the mechanism underlying a large range of biochemical and physiological processes

Wnt addiction of genetically defined cancers reversed by PORCN inhibition

Enhanced sensitivity to Wnts is an emerging hallmark of a subset of cancers, defined in part by mutations regulating the abundance of their receptors. Whether these mutations identify a clinical opportunity is an important question. Inhibition of Wnt secretion by blocking an essential post-translational modification, palmitoleation, provides a useful therapeutic intervention. We developed a novel potent, orally available PORCN inhibitor, ETC-1922159 (henceforth called ETC-159) that blocks the secretion and activity of all Wnts. ETC-159 is remarkably effective in treating RSPO-translocation bearing colorectal cancer (CRC) patient-derived xenografts. This is the first example of effective targeted therapy for this subset of CRC. Consistent with a central role of Wnt signaling in regulation of gene expression, inhibition of PORCN in RSPO3-translocated cancers causes a marked remodeling of the transcriptome, with loss of cell cycle, stem cell and proliferation genes, and an increase in differentiation markers. Inhibition of Wnt signaling by PORCN inhibition holds promise as differentiation therapy in genetically defined human cancers

A Linear Framework for Time-Scale Separation in Nonlinear Biochemical Systems

Cellular physiology is implemented by formidably complex biochemical systems with highly nonlinear dynamics, presenting a challenge for both experiment and theory. Time-scale separation has been one of the few theoretical methods for distilling general principles from such complexity. It has provided essential insights in areas such as enzyme kinetics, allosteric enzymes, G-protein coupled receptors, ion channels, gene regulation and post-translational modification. In each case, internal molecular complexity has been eliminated, leading to rational algebraic expressions among the remaining components. This has yielded familiar formulas such as those of Michaelis-Menten in enzyme kinetics, Monod-Wyman-Changeux in allostery and Ackers-Johnson-Shea in gene regulation. Here we show that these calculations are all instances of a single graph-theoretic framework. Despite the biochemical nonlinearity to which it is applied, this framework is entirely linear, yet requires no approximation. We show that elimination of internal complexity is feasible when the relevant graph is strongly connected. The framework provides a new methodology with the potential to subdue combinatorial explosion at the molecular level

Effects of grain source and processing methods on the nutritional profile and digestibility of grain amaranth

Amaranth grain is reputed to have a high nutritional value, and as a plant, be tolerant to adverse weather conditions. This suggests that grain amaranth could be useful in tackling malnutrition and the growing burden of cardiometabolic diseases. However, there is insufficient knowledge at present about how the nutrient composition and digestibility of amaranth grain varies with growing environment, crop genotype, and post-harvest processing. We investigated the effect of the source and processing of amaranth grains on the digestibility of protein and lipid present in the grains. There was variation in the composition and digestibility of raw grains from different sources, indicating a role of genotype and/or growing environment which warrants further investigation. The greatest differences in digestibility were measured between the different processing techniques. This indicates that efforts to increase the cultivation and consumption of grain amaranth need to be supported by education about effective processing and preparation techniques

Macrophage-derived Extracellular Vesicle packaged WNTs rescue intestinal stem cells 2 and enhance survival after radiation injury

WNT/β-catenin signalling is crucial for intestinal homoeostasis. The intestinal epithelium and stroma are the major source of WNT ligands but their origin and role in intestinal stem cell (ISC) and epithelial repair remains unknown. Macrophages are a major constituent of the intestinal stroma. Here, we analyse the role of macrophage-derived WNT in intestinal repair in mice by inhibiting their release using a macrophage-restricted ablation of Porcupine, a gene essential for WNT synthesis. Such Porcn-depleted mice have normal intestinal morphology but are hypersensitive to radiation injury in the intestine compared with wild-type (WT) littermates. Porcn-null mice are rescued from radiation lethality by treatment with WT but not Porcn-null bone marrow macrophage-conditioned medium (CM). Depletion of extracellular vesicles (EV) from the macrophage CM removes WNT function and its ability to rescue ISCs from radiation lethality. Therefore macrophage-derived EV-packaged WNTs are essential for regenerative response of intestine against radiation