Supersymmetric monopole dynamics

We study the supersymmetric quantum mechanics of monopoles in bosonic, N = 2 and N = 4 supersymmetric Yang-Mills-Higgs theory, with particular emphasis on monopoles of charge{(1; 1) in a theory with gauge group SU(3) spontaneously broken to U(1) £ U(1). In the moduli space approximation, the quantum states of bosonic monopoles can be described by functions on the moduli space. For N = 2 supersymmetric monopoles, quantum states can be interpreted as either spinors or anti-holomorphic forms on the moduli space. The quantum states of the N = 4 supersymmetric monopole correspond to general di®erential forms on the moduli space. In each case, we review the moduli space approximation and derive general expressions for the supercharges as di®erential operators. In the geometrical language of forms on the moduli space, the Hamiltonian is proportional to the Laplacian acting on forms. We propose a general expression for the total angular momentum operator and verify its commutation relations with the supercharges. We use the known metric structure of the moduli space of charge{(1; 1) monopoles to show that there are no quantum bound states of such monopoles in the moduli space approximation. We exhibit scattering states and compute the corresponding di®er- ential cross sections. Using the general expressions for the supercharges we construct the short supermultiplet of supersymmetric monopoles, and study its decomposition under the proposed angular momentum operator

The Arabidopsis thaliana SOMATIC EMBRYOGENESIS RECEPTOR-LIKE KINASES1 and 2 control male sporogenesis

The Arabidopsis thaliana SOMATIC EMBRYOGENESIS RECEPTOR-LIKE KINASE (SERK) family of plasma membrane receptors consists of five closely related members. The SERK1 and SERK2 genes show a complex expression pattern throughout development. Both are expressed in anther primordia up to the second parietal division. After this point, expression ceases in the sporocytes and is continued in the tapetum and middle layer precursors. Single knockout mutants of SERK1 and SERK2 show no obvious phenotypes. Double mutants of SERK1 and SERK2 are completely male sterile due to a failure in tapetum specification. Fertility can be restored by a single copy of either gene. The SERK1 and SERK2 proteins can form homodimers or heterodimers in vivo, suggesting they are interchangeable in the SERK1/SERK2 signaling comple

Biocatalytic conversion of epoxides

Epoxides are attractive intermediates for producing chiral compounds. Important biocatalytic reactions involving epoxides include epoxide hydrolase mediated kinetic resolution, leading to the formation of diols and enantiopure remaining substrates, and enantioconvergent enzymatic hydrolysis, which gives high yields of a single enantiomer from racemic mixtures. Epoxides can also be converted by non-hydrolytic enantioselective ring opening, using alternative anionic nucleophiles; these reactions can be catalysed by haloalcohol dehalogenases. The differences in scope of these enzymatic conversions is related to their different catalytic mechanisms, which involve, respectively, covalent catalysis with an aspartate carboxylate as the nucleophile and non-covalent catalysis with a tyrosine that acts as a general acid-base. The emerging new possibilities for enantioselective biocatalytic conversion of epoxides suggests that their importance in green chemistry will grow.

The effects of social media on political party perception and voting behavior

This study sought to determine to what extent social media influences political party perception (PPP) and political voting behavior. Based on literature a conceptual model was developed which measures political interest, political trust, religion and the use of social media and their effects on PPP and voting behavior. Using an online questionnaire the conceptual model was tested towards and during the Dutch national elections of 2010. Although data analysis indicates several significant effects on PPP, voting behavior is solely determined by political interest. Certain effects of social media seem evident, though further research is necessary in funding and legitimizing its future role in political marketing

Multi-band signal processor for digital audio signals

A method includes: processing the digital audio input signal to generate M delayed digital audio signal samples; converting the delayed digital audio signal samples to frequency domain representation in N number of frequency bands to compute respective signal spectrum values; determining respective signal level estimates; computing respective frequency domain gain coefficients based on the respective signal level estimates and band gain laws; transforming the frequency domain gain coefficients to time domain representation to produce M time-varying filter coefficients of a processing filter; convolving the M delayed digital audio signal samples with the time-varying filter coefficients to produce the processed digital output signal; and updating the delayed digital audio signal samples in accordance with a sample-by-sample or a predetermined block rate; wherein two of the signal spectrum values for at least two of the frequency bands are updated at different rates; and wherein M and N are positive integer numbers.</p

Linear motor motion control using a learning feedforward controller

The design and realization of an online learning motion controller for a linear motor is presented, and its usefulness is evaluated. The controller consists of two components: (1) a model-based feedback component, and (2) a learning feedforward component. The feedback component is designed on the basis of a simple second-order linear model, which is known to have structural errors. In the design, an emphasis is placed on robustness. The learning feedforward component is a neural-network-based controller, comprised of a one-hidden-layer structure with second-order B-spline basis functions. Simulations and experimental evaluations show that, with little effort, a high-performance motion system can be obtained with this approach