Thermodynamics and quark susceptibilities: a Monte-Carlo approach to the PNJL model

The Monte-Carlo method is applied to the Polyakov-loop extended Nambu--Jona-Lasinio (PNJL) model. This leads beyond the saddle-point approximation in a mean-field calculation and introduces fluctuations around the mean fields. We study the impact of fluctuations on the thermodynamics of the model, both in the case of pure gauge theory and including two quark flavors. In the two-flavor case, we calculate the second-order Taylor expansion coefficients of the thermodynamic grand canonical partition function with respect to the quark chemical potential and present a comparison with extrapolations from lattice QCD. We show that the introduction of fluctuations produces only small changes in the behavior of the order parameters for chiral symmetry restoration and the deconfinement transition. On the other hand, we find that fluctuations are necessary in order to reproduce lattice data for the flavor non-diagonal quark susceptibilities. Of particular importance are pion fields, the contribution of which is strictly zero in the saddle point approximation

Measurement of focusing properties for high numerical aperture optics using an automated submicron beamprofiler

The focusing properties of three aspheric lenses with numerical aperture (NA) between 0.53 and 0.68 were directly measured using an interferometrically referenced scanning knife-edge beam profiler with sub-micron resolution. The results obtained for two of the three lenses tested were in agreement with paraxial gaussian beam theory. It was also found that the highest NA aspheric lens which was designed for 830nm was not diffraction limited at 633nm. This process was automated using motorized translation stages and provides a direct method for testing the design specifications of high numerical aperture optics.Comment: 6 pages 4 figure

On the homomorphism order of labeled posets

Partially ordered sets labeled with k labels (k-posets) and their homomorphisms are examined. We give a representation of directed graphs by k-posets; this provides a new proof of the universality of the homomorphism order of k-posets. This universal order is a distributive lattice. We investigate some other properties, namely the infinite distributivity, the computation of infinite suprema and infima, and the complexity of certain decision problems involving the homomorphism order of k-posets. Sublattices are also examined.Comment: 14 page

On the reduction of the CSP dichotomy conjecture to digraphs

It is well known that the constraint satisfaction problem over general relational structures can be reduced in polynomial time to digraphs. We present a simple variant of such a reduction and use it to show that the algebraic dichotomy conjecture is equivalent to its restriction to digraphs and that the polynomial reduction can be made in logspace. We also show that our reduction preserves the bounded width property, i.e., solvability by local consistency methods. We discuss further algorithmic properties that are preserved and related open problems.Comment: 34 pages. Article is to appear in CP2013. This version includes two appendices with proofs of claims omitted from the main articl

Chemical shift assignments of the N-terminal domain of PSD95 (PSD95-NT)

Postsynaptic density protein-95 (PSD95) contributes to the postsynaptic architecture of neuronal synapses and plays an important role in controlling synaptic plasticity. The N-terminal domain of PSD95 (residues 1–71, called PSD95-NT) interacts with target proteins (calmodulin, α-actinin-1 and CDKL5), which regulate the Ca2+-dependent degradation of glutamate receptors. We report complete backbone NMR chemical shift assignments of PSD95-NT (BMRB No. 50752)

Three-dimensional nanoscopy of colloidal crystals.

We demonstrate the direct three-dimensional imaging of densely packed colloidal nanostructures using stimulated emission depletion microscopy. A combination of two de-excitation patterns yields a resolution of 43 nm in the lateral and 125 nm in the axial direction and an effective focal volume that is by 126-fold smaller than that of a corresponding confocal microscope. The mapping of a model system of spheres organized by confined convective assembly unambiguously identified face-centered cubic, hexagonal close-packed, random hexagonal close-packed, and body-centered cubic structures. An increasing need for noninvasive visualization on the nanoscale has fueled the development of far-field optical microscopy with resolution far below the wavelength of light.1,2 In materials science, structural studies with length scales of interest in the (sub-) micrometer range have typically been conducted either by collective scattering-based techniques or electron and scanning probe microscopes. Far-field optical methods however retain the advantage of simultaneously providing local, dynamic, and noninvasiv

The Effect of Talker Identity on Dialect Processing

Recent work has suggested that bilingual listeners use the visual identity of the talker to form expectations about the language the talker will use, which then facilitates lexical processing. In the current study, we extend this work to see if there are analogous effects of talker identity on dialect processing, and whether the impact of talker identity depends on the regional background of the listener. Six actresses recorded stimuli in two dialectal guises, performing Southern US accents and standardized, regionally nonspecific US accents. Participants were introduced to the actresses via video as having one particular dialect type (familiarization), and then later did an audio-visual lexical decision task (test) where some trials would be dialectally congruent and some trials would be dialectally incongruent with their earlier experience of that talker. US English listeners from both Southern and non-Southern dialect regions participated. Listeners who self-reported having (Southern) accents were impacted by talker dialect congruence, performing best with a given dialect when it matched their experience of that talker. However, other listeners were not impacted by congruency, performing better with standardized tokens regardless. This mirrors findings in bilingualism research that early bilinguals are more sensitive to talker language pairing than monolinguals or late bilinguals. We ran three additional conditions without video and/or without a familiarization stage to confirm the importance of each component to observing the effect. Generally, without familiarization, Southern US listeners performed worse with Southern vs. standardized tokens, suggesting that without strong contextual cues indicating otherwise, these listeners may expect standardized tokens in experimental settings. There is some evidence that all listeners were somewhat sensitive to talker identity even from voice alone

Impact of indigenous storage systems and insect infestation on the contamination of maize with fumonisins

Four storage systems of maize commonly used by farmers in Benin, West Africa, were tested to determine their impact on infection of maize by Fusarium and subsequent contamination with fumonisins. The study showed that Fusarium incidence was significantly higher when maize was stored on a cemented floor in a house, a non ventilated facility (40.3 ± 17.4%), than in the other tested systems (p < 0.05). The lowest Fusarium incidence was recorded when maize was stored in a bamboo granary that is a ventilated facility (25.5 ± 13.5%) (p < 0.05). All maize samples from the tested storage systems were found to be fumonisin positive, with levels ranging from 0.6 to 2.4 mg/kg. Fumonisin level, overall, was found to decrease over the storage period, but not significantly in all the tested storage systems. Damage by lepidopterous pests was significantly and positively correlated with both infection of maize with Fusarium and contamination by fumonisin. In contrary, damage by coleopterous insects was significantly and negatively correlated with infection of maize with Fusarium and contamination by fumonisin. Avoiding the use of non-ventilated systems to store maize and reducing insect infestation in field and during storage are very important recommendations for farmers.Keywords: Maize, storage systems, Fusarium, fumonisins, insect infestatio

Designing chromatic optical retarder stacks for segmented next-generation easySTED phase plates

Fluorescence nanoscopy methods based on the RESOLFT principle, such as beam-scanning STED nanoscopy, require the co-alignment of optical beams for molecular state (on/off) switching and fluorescence excitation. The complexity and stability of the beam alignment can be drastically simplified and improved by using a single-mode fibre as the sole light source for all required laser beams. This in turn then requires a chromatic optical element for shaping the off-switching beam into a focal-plane donut while simultaneously leaving the focal intensity distributions at other wavelengths shaped as regular focal spots. Here we describe novel designs of such so-called ‘easySTED phase plates’ and provide a rationale how to find the desired spectral signature for combinations of multiple wavelengths