Bielefeld University

About: Bielefeld University is a education organization based out in Bielefeld, Nordrhein-Westfalen, Germany. It is known for research contribution in the topics: Population & Quantum chromodynamics. The organization has 10123 authors who have published 26576 publications receiving 728250 citations. The organization is also known as: University of Bielefeld & UNIVERSITAET BIELEFELD.

Novel regulators in photosynthetic redox control of plant metabolism and gene expression.

Abstract: Reduction-oxidation (redox) reactions are an essential part of cell metabolism and represent a major fraction of all catabolic and anabolic reactions. Their dominant characteristic is that they generate and consume compounds with in part highly negative redox potential. Redox reactions occur at many

Amygdala, affect and cognition: evidence from 10 patients with Urbach-Wiethe disease

Abstract: Patients with Urbach-Wiethe disease constitute a unique nature experiment as more than half have bilaterally symmetrical damage in the amygdaloid region. Ten such patients were studied neuropsychologically and, nine of them, neuroradiologically with static (CT) and functional imaging techniques [single-photon emission computed tomography (SPECT) and PET]. Their principal bilateral amygdala damage was confirmed. Neuropsychologically, the patients showed cognitively little deviation from normal subjects, while they differed emotionally. This was evident in their judgement of all emotions in facial expressions, in an odour-figure association test as well as in remembering negative and positive pictures. This suggests that the human amygdala influences both negative and positive emotional processing.

Representation of integers by positive ternary quadratic forms and equidistribution of lattice points on ellipsoids.

Abstract: It is a classical problem to find an asymptotic formula for the number of integral points in a region on the ellipsoid q(x l . . . . . x r ) = n as n--+ oo where q is a positive definite integral quadratic form. In particular, one wants to prove that the integral points on such an ellipsoid are asymptotically uniformly distributed. For r > 4, this problem has been solved by Pommerenke [Pom] (with some necessary restrictions on the set of numbers in which n tends to infinity if r = 4). Improvements of the error term have been obtained in [Ma, Pod, Go-Fo l ] . The case r = 3 has remained open so far; in fact one could not even give an unconditional proof of such a formula for the number of integral points on the whole ellipsoid (i.e., the number of representations of n by the quadratic form q). Linnik's ergodic method has been applied to this problem by several authors (see [Pe, Tel and references given there). However, the method requires imposing a condition on the quadratic residue character of n modulo some fixed prime. In order to remove it one has to assume certain unproved hypotheses concerning zeros of Dirichlet L-functions. Recent advances in the theory of modular forms of half integral weight [I, Du] as well as in the theory of quadratic forms [SP1, SP2, SP3] make it now possible to obtain the desired asymptotic formula unconditionally for r = 3 following the well known approach that has been succesful for r>4 . The only restrictions still present resemble those for r=4 . How this may be done for a 3-dimensional sphere has been shown in [Du] and [-Go-Fo2]. Although each single step of this proof is in the literature, it might be of some interest to collect them in one place and thus make this beautiful result more easily accessible. Since it does not involve much extra work, we also allow congruence conditions on the integral points.

Colloidal crystals made of poly( N -isopropylacrylamide) microgel particles

Abstract: Poly (N-isopropylacrylamide) microgel particles are found to form colloidal crystals similar to those occurring in typical hard-sphere colloids like poly(methylmethacrylate) beads. Samples made of particles with different crosslinker concentrations are investigated and their deswelling ratio is determined using dynamic light scattering. Small-angle neutron scattering data are also presented and analysed in terms of a face-centred-cubic crystal structure. The characteristic length, a, of the elementary cell is found to be 535 +/- 16 and 495 +/- 15 nm for the two systems investigated. This leads to particle radii of 189 +/- 6 and 175 +/- 5 nm, respectively. These values compare well to the radii determined using several different methods.

Photoinduced formation of reversible dye radicals and their impact on super-resolution imaging

Abstract: Radical ions of organic dyes are highly reactive species and have been studied for decades by transient absorption spectroscopy and pulse radiolysis experiments in oxygen-depleted solution. Here we show by continuous wave EPR, absorption, and fluorescence experiments that the triplet state of rhodamine dyes can be photoreduced by thiols to form stable radical anions in aqueous solution with a lifetime of up to several hours. Our data demonstrate that reduction of the triplet state and photoinduced oxidation of reactive intermediates by oxygen represents a general mechanism for reversible photoswitching of dyes in aqueous thiol-containing solutions highlighting the key role of molecular oxygen for super-resolution fluorescence imaging. Since cells contain the thiol glutathione at millimolar concentrations and reactive oxygen species are formed as side products our findings are of consequence for live cell fluorescence microscopy.