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Lipopolysaccharides (LPS) produced by Rhizobium etli can make potato roots resistant to the potato cyst nematode. LPS inhibited nematode infection of the roots when present in concentrations as low as 0.1 mg per ml.

Abstract We study particular families of bad 3d N $$ \mathcal{N} $$ = 4 quiver gauge theories, whose Higgs branches consist of many cones. We show the role of a novel brane configuration in realizing the Higgs moduli for each distinct cone. Through brane constructions, magnetic quivers, Hasse diagrams, and Hilbert series computations we study the intricate structure of the classical Higgs branches. These Higgs branches are both non-normal (since they consist of multiple cones) and non-reduced (due to the presence of nilpotent operators in the chiral ring). Applying the principle of inversion to the classical Higgs branch Hasse diagrams, we conjecture the quantum Coulomb branch Hasse diagrams. These Coulomb branches have several most singular loci, corresponding to the several cones in the Higgs branch. We propose the Hasse diagrams of the full quantum moduli spaces of our theories. The quivers we study can be taken to be 5d effective gauge theories living on brane webs. Their infinite coupling theories have Higgs branches which also consist of multiple cones. Some of these cones have decorated magnetic quivers, whose 3d Coulomb branches remain elusive.

Understanding the mechanisms of action of interventions is a major general goal of scientific inquiry. The collection of statistical methods that use data to achieve this goal is referred to as mediation analysis. Natural direct and indirect effects provide a definition of mediation that matches scientific intuition, but they are not identified in the presence of time-varying confounding. Interventional effects have been proposed as a solution to this problem, but existing estimation methods are limited to assuming simple (e.g., linear) and unrealistic relations between the mediators, treatments, and confounders. We present an identification result for interventional effects in a general longitudinal data structure that allows flexibility in the specification of treatment-outcome, treatment-mediator, and mediator-outcome relationships. Identification is achieved under the standard no-unmeasured-confounders and positivity assumptions. In this article, we study semi-parametric efficiency theory for the functional identifying the mediation parameter, including the non-parametric efficiency bound, and was used to propose non-parametrically efficient estimators. Implementation of our estimators only relies on the availability of regression algorithms, and the estimators in a general framework that allows the analyst to use arbitrary regression machinery were developed. The estimators are doubly robust, n\sqrt{n}-consistent, asymptotically Gaussian, under slow convergence rates for the regression algorithms used. This allows the use of flexible machine learning for regression while permitting uncertainty quantification through confidence intervals and pp-values. A free and open-source R package implementing the methods is available on GitHub. The proposed estimator to a motivating example from a trial of two medications for opioid-use disorder was applied, where we estimate the extent to which differences between the two treatments on risk of opioid use are mediated by craving symptoms.

Interventional effects for mediation analysis were proposed as a solution to the lack of identifiability of natural (in)direct effects in the presence of a mediator-outcome confounder affected by exposure. We present a theoretical and computational study of the properties of the interventional (in)direct effect estimands based on the efficient influence function in the nonparametric statistical model. We use the efficient influence function to develop two asymptotically optimal nonparametric estimators that leverage data-adaptive regression for the estimation of nuisance parameters: a one-step estimator and a targeted minimum loss estimator. We further present results establishing the conditions under which these estimators are consistent, multiply robust, |$n^{1/2}$| -consistent and efficient. We illustrate the finite-sample performance of the estimators and corroborate our theoretical results in a simulation study. We also demonstrate the use of the estimators in our motivating application to elucidate the mechanisms behind the unintended harmful effects that a housing intervention had on risky behaviour in adolescent girls. [ABSTRACT FROM AUTHOR]

A study of the DNA binding properties of MASH-1 using circular dichroism spectroscopy and electrophoretic mobility shift assays (EMSA) shows that the basic-helix-loop-helix (BHLH) domain of MASH-1 undergoes a conformational change from mainly unfolded to a largely alpha-helical form when bound to DNA. This change is not affected by the specific DNA sequence. The DNA binding specificity of MASH-1 is not significantly increased by the formation of an heterodimer with the E12 protein.

4,5-dihydro-1-phenyl-1H-2,4-benzodiazepines are conformationally studied using X-ray crystallography, nuclear Overhauser, NMR and grid searching techniques. X-ray studies indicate conformational equilibrium between axial orientations and equatorial free bases. The salt favors axial conformation even though the free base is present between the two. The analogs of 1-methyl also favor axial orientation of the phenyl rings.

The use of fluorine atom for achieving regiospecific control over the ring closures of tertiary bicyclic cations is demonstrated. The rearrangement of fluorine-synthesized cyclopentenols are studied to establish the stereochemistry of their tetrasubstituted fluoro alkene bonds. Results show that the fluorine atom is capable of controlling the regiochemistry to produce a stable product with a 6-membered ring.

The use of the fluorine atom as a cation-stabilizing agent for enhancing polyene cyclizations is demonstrated. A cyclization substrate is synthesized both in the racemic and optically active acetal forms. The quarternary fluorine atom is then deposited at pro-C-8 by hydrogen stereoselectivity with retention of configuration. Results show that the cyclization of the acetal gives a substantial yield of fluorotetracycle which can be converted into a known steroid type.

A new method for the stereoselective synthesis of polyenic cyclization substrates is presented. The method replaces the vinyl hydrogen of an E-trisubstotuted olefinic bond with a fluorine atom. This approach enhances the formation of polycyclic products as the vinyl fluoride function has been proven to be a good terminator of polyene cyclizations. It also allows the performance of reactions under very mild conditions resulting in high-yield crystallizations.

A new synthetic route to the 4-oxo-L-proline cyclic dimer, a symmetric and highly functionalized cyclo(Prn-Prn), leads to a technique for effective differentiation of homotopic carbonyls. Topological difficulties that prevent synthesis via the known cyclo(Hyp-Hyp) forces the preparation to start from N-Cbz-trans-4-hydroxy-L-proline, so that oxidation of the alcohol precedes dimerization. This allows the five-step production of a key intermediate ketal in 16% yield and 97% isomeric purity. The ketal serves as a common substrate for other cyclo(Prn-Prn) analogues in which the C2 symmetry of the parent dimer is masked.