Fractal Conductance Fluctuations of Classical Origin

In mesoscopic systems conductance fluctuations are a sensitive probe of electron dynamics and chaotic phenomena. We show that the conductance of a purely classical chaotic system with either fully chaotic or mixed phase space generically exhibits fractal conductance fluctuations unrelated to quantum interference. This might explain the unexpected dependence of the fractal dimension of the conductance curves on the (quantum) phase breaking length observed in experiments on semiconductor quantum dots.Comment: 5 pages, 4 figures, to appear in PR

Isolated resonances in conductance fluctuations in ballistic billiards

We study numerically quantum transport through a billiard with a classically mixed phase space. In particular, we calculate the conductance and Wigner delay time by employing a recursive Green's function method. We find sharp, isolated resonances with a broad distribution of resonance widths in both the conductance and the Wigner time, in contrast to the well-known smooth conductance fluctuations of completely chaotic billiards. In order to elucidate the origin of the isolated resonances, we calculate the associated scattering states as well as the eigenstates of the corresponding closed system. As a result, we find a one-to-one correspondence between the resonant scattering states and eigenstates of the closed system. The broad distribution of resonance widths is traced to the structure of the classical phase space. Husimi representations of the resonant scattering states show a strong overlap either with the regular regions in phase space or with the hierarchical parts surrounding the regular regions. We are thus lead to a classification of the resonant states into regular and hierarchical, depending on their phase space portrait.Comment: 2 pages, 5 figures, to be published in J. Phys. Soc. Jpn., proceedings Localisation 2002 (Tokyo, Japan

Temporal-spatial Patterns of Noctuinae Communities (Lep. Noctuidae) in Hungarian Apple Orchards (Apple Ecosystem Research)

In our present study we aimed to recognize the temporal and spatial patterns of Noctuinae communities (Lep.Noctuidae) of four differently managed apple orchards laying in different localities of Hungary. Data were obtained by light trap collection. The quantitative data resulting from our investigations were analyzed by multivariate methods and were also analyzed by their diversity characteristics.As a result connections were found regarding the diversities of species and individuals, the patterns of occurrence and phenological properties. The studies were based on 8497 individuals of 39 species

Textural Properties and Structure of Starch-Reinforced Surimi Gels as Affected by Heat-Setting

The gel forming behavior of red hake (Urophycis chuss) surimi with and without starch and its relationship to the structure of the gel matrix were studied. For surimi gels without starch, a combination of preheat- setting at 40 C and cooking at 90 C resulted in significantly greater gel strength than cooking alone. However, preheat - setting of gels containing wheat or potato starch had no significant effect on gel strength demonstrating an opposite trend in gel strength due to the differences in swelling power, water holding ability and gelatinization temperature between potato and wheat starches. This difference in gel forming behavior due to the sources of starch and heat- setting prior to cooking correlated with changes in the structure of the matrix as evidenced by the results of image analysis. An examination of the microstructure of the gel matrix by light and electron microscopy showed that the structural differences may be due to the different protein matrix density as reflected in the increased gel strength

Textural and Microstructural Properties of Frozen Fish Mince as Affected by the Addition of Nonfish Proteins and Sorbitol

Changes in textural and microstructural properties of washed and unwashed frozen fish mince were studied as affected by the addition of non fish proteins (soy protein isolate, milk protein isolate, egg white, and wheat gluten at 2 , 4 or 6%) and 6% crystalline sorbitol. Soy and milk proteins and sorbitol reduced the hardness of frozen fish mince, while egg white and wheat gluten made the texture firmer without rubberiness developing after frozen storage. All nonfish proteins and sorbitol stabilized the myofibrillar organization by reducing freeze-induced contraction of myofibrils. The mechanisms of reducing texture hardening appear to be different between sorbitol and nonfish proteins. Water binding properties and dispersibility made the difference among nonfish proteins in reducing freeze-contraction of myofibrils. Nonfish proteins not only reduced texture hardening during frozen storage, but also modified texture during cooki ng as they underwent thermal gelation specific to each protein used

Generalised coherent point drift for group-wise registration of multi-dimensional point sets

In this paper we propose a probabilistic approach to group-wise registration of unstructured high-dimensional point sets. We focus on registration of generalised point sets which encapsulate both the positions of points on surface boundaries and corresponding normal vectors describing local surface geometry. Richer descriptions of shape can be especially valuable in applications involving complex and intricate variations in geometry, where spatial position alone is an unreliable descriptor for shape registration. A hybrid mixture model combining Student’s t and Von-Mises-Fisher distributions is proposed to model position and orientation components of the point sets, respectively. A group-wise rigid and non-rigid registration framework is then formulated on this basis. Two clinical data sets, comprising 27 brain ventricle and 15 heart shapes, were used to assess registration accuracy. Significant improvement in accuracy and anatomical validity of the estimated correspondences was achieved using the proposed approach, relative to state-of-the-art point set registration approaches, which consider spatial positions alone

The catabolite repressor protein-cyclic AMP complex regulates csgD and biofilm formation in uropathogenic Escherichia coli

The extracellular matrix protects Escherichia coli from immune cells, oxidative stress, predation, and other environmental stresses. Production of the E. coli extracellular matrix is regulated by transcription factors that are tuned to environmental conditions. The biofilm master regulator protein CsgD upregulates curli and cellulose, the two major polymers in the extracellular matrix of uropathogenic E. coli (UPEC) biofilms. We found that cyclic AMP (cAMP) regulates curli, cellulose, and UPEC biofilms through csgD. The alarmone cAMP is produced by adenylate cyclase (CyaA), and deletion of cyaA resulted in reduced extracellular matrix production and biofilm formation. The catabolite repressor protein (CRP) positively regulated csgD transcription, leading to curli and cellulose production in the UPEC isolate, UTI89. Glucose, a known inhibitor of CyaA activity, blocked extracellular matrix formation when added to the growth medium. The mutant strains ΔcyaA and Δcrp did not produce rugose biofilms, pellicles, curli, cellulose, or CsgD. Three putative CRP binding sites were identified within the csgD-csgB intergenic region, and purified CRP could gel shift the csgD-csgB intergenic region. Additionally, we found that CRP binded upstream of kpsMT, which encodes machinery for K1 capsule production. Together our work shows that cAMP and CRP influence E. coli biofilms through transcriptional regulation of csgD. IMPORTANCE The catabolite repressor protein (CRP)-cyclic AMP (cAMP) complex influences the transcription of ∼7% of genes on the Escherichia coli chromosome (D. Zheng, C. Constantinidou, J. L. Hobman, and S. D. Minchin, Nucleic Acids Res 32:5874–5893, 2004, https://dx.doi.org/10.1093/nar/gkh908). Glucose inhibits E. coli biofilm formation, and ΔcyaA and Δcrp mutants show impaired biofilm formation (D. W. Jackson, J.W. Simecka, and T. Romeo, J Bacteriol 184:3406–3410, 2002, https://dx.doi.org/10.1128/JB.184.12.3406-3410.2002). We determined that the cAMP-CRP complex regulates curli and cellulose production and the formation of rugose and pellicle biofilms through csgD. Additionally, we propose that cAMP may work as a signaling compound for uropathogenic E. coli (UPEC) to transition from the bladder lumen to inside epithelial cells for intracellular bacterial community formation through K1 capsule regulation

Metal-insulator transitions in cyclotron resonance of periodic nanostructures due to avoided band crossings

A recently found metal-insulator transition in a model for cyclotron resonance in a two-dimensional periodic potential is investigated by means of spectral properties of the time evolution operator. The previously found dynamical signatures of the transition are explained in terms of avoided band crossings due to the change of the external electric field. The occurrence of a cross-like transport is predicted and numerically confirmed

Mechanical Stress Inference for Two Dimensional Cell Arrays

Many morphogenetic processes involve mechanical rearrangement of epithelial tissues that is driven by precisely regulated cytoskeletal forces and cell adhesion. The mechanical state of the cell and intercellular adhesion are not only the targets of regulation, but are themselves likely signals that coordinate developmental process. Yet, because it is difficult to directly measure mechanical stress {\it in vivo} on sub-cellular scale, little is understood about the role of mechanics of development. Here we present an alternative approach which takes advantage of the recent progress in live imaging of morphogenetic processes and uses computational analysis of high resolution images of epithelial tissues to infer relative magnitude of forces acting within and between cells. We model intracellular stress in terms of bulk pressure and interfacial tension, allowing these parameters to vary from cell to cell and from interface to interface. Assuming that epithelial cell layers are close to mechanical equilibrium, we use the observed geometry of the two dimensional cell array to infer interfacial tensions and intracellular pressures. Here we present the mathematical formulation of the proposed Mechanical Inverse method and apply it to the analysis of epithelial cell layers observed at the onset of ventral furrow formation in the {\it Drosophila} embryo and in the process of hair-cell determination in the avian cochlea. The analysis reveals mechanical anisotropy in the former process and mechanical heterogeneity, correlated with cell differentiation, in the latter process. The method opens a way for quantitative and detailed experimental tests of models of cell and tissue mechanics