Evolutionary Dynamics and Optimization: Neutral Networks as Model-Landscapes for RNA Secondary-Structure Folding-Landscapes

We view the folding of RNA-sequences as a map that assigns a pattern of base pairings to each sequence, known as secondary structure. These preimages can be constructed as random graphs (i.e. the neutral networks associated to the structure $s$). By interpreting the secondary structure as biological information we can formulate the so called Error Threshold of Shapes as an extension of Eigen's et al. concept of an error threshold in the single peak landscape. Analogue to the approach of Derrida & Peliti for a of the population on the neutral network. On the one hand this model of a single shape landscape allows the derivation of analytical results, on the other hand the concept gives rise to study various scenarios by means of simulations, e.g. the interaction of two different networks. It turns out that the intersection of two sets of compatible sequences (with respect to the pair of secondary structures) plays a key role in the search for ''fitter'' secondary structures.Comment: 20 pages, uuencoded compressed postscript-file, Proc. of ECAL '95 conference, to appear., email: chris @ imb-jena.d

Structure–property relationships of iron arsenide superconductors

Iron based superconductors sent material scientists into a renewed excitement reminiscent of the time when the first high-Tc superconductors were discovered 25 years ago. This feature article reviews relationships between structural chemistry and magnetic as well as superconducting properties of iron arsenide compounds, which are outstandingly rich and uniquely coupled. Particular attention is paid to the nature of the structural phase transitions of the parent compounds and their possible origins, on effects of doping on the crystal structures and on the coexistence of magnetic ordering and superconductivity. In spite of the many fascinating insights that have already enriched the research on superconductivity, many questions are still open and prove iron based superconductors to be a good recipe for future discoveries in this lively field

Structure of Sn_1-xGe_x random alloys as obtained from the coherent potential approximation

The structure of the Sn1-xGex random alloys is studied using density functional theory and the coherent potential approximation. We report on the deviation of the Sn1-xGex alloys from Vegard's law, addressing their full compositional range. The findings are compared to the related Si1-xGex alloys and to experimental results. Interestingly, the deviation from Vegard's law is quantitatively and qualitatively different between the Sn1-xGex and Si1-xGex alloys. An almost linear dependence of the bulk modulus as a function of composition is found for Si1-xGex, whereas for Sn1-xGex the dependence is strongly nonlinear

Combinatorial Penalties: Which structures are preserved by convex relaxations?

We consider the homogeneous and the non-homogeneous convex relaxations for combinatorial penalty functions defined on support sets. Our study identifies key differences in the tightness of the resulting relaxations through the notion of the lower combinatorial envelope of a set-function along with new necessary conditions for support identification. We then propose a general adaptive estimator for convex monotone regularizers, and derive new sufficient conditions for support recovery in the asymptotic setting

The Structure of 401(k) Fees

Increasingly, people are depending on 401(k) and similar defined contribution plans sponsored by their employers for their retirement income. As a result, participants in these plans also are paying more of their plans’ costs, ranging from administration and sales expenses to the cost of managing investments. These costs can take a substantial toll on retirement savings. Over a 30-year career, for example, paying an annual fee of 50 basis points can reduce the purchasing power of savings at the time of retirement by one-eighth. Employers who sponsor 401(k) plans have a fiduciary responsibility to ensure their plans’ fees are reasonable and communicated to participants. Recently, the Government Accountability Office reported that participants need more information and sponsors need to disclose this information more effectively to fulfill this responsibility. The Department of Labor is revising regulations to require sponsors to report the fees of their plans more clearly to their employees. Congress also has been holding hearings, inquiring if greater disclosure would help reduce costs within 401(k) plans...

The structure of gravel-bed flow with intermediate submergence: a laboratory study

The paper reports an experimental study of the flow structure over an immobile gravel bed in open channel at intermediate submergence, with particular focus on the near-bed region. The experiments consisted of velocity measurements using three-component (stereoscopic) Particle Image Velocimetry (PIV) in near-bed horizontal plane and two-component PIV in three vertical planes that covered three distinctly different hydraulic scenarios where the ratio of flow depth to roughness height (i.e., relative submergence) changes from 7.5 to 10.8. Detailed velocity measurements were supplemented with fine-scale bed elevation data obtained with a laser scanner. The data revealed longitudinal low-momentum and high-momentum "strips'' in the time-averaged velocity field, likely induced by secondary currents. This depth-scale pattern was superimposed with particle-scale patches of flow heterogeneity induced by gravel particle protrusions. A similar picture emerged when considering second-order velocity moments. The interaction between the flow field and gravel-bed protrusions is assessed using cross correlations of velocity components and bed elevations in a horizontal plane just above gravel particle crests. The cross correlations suggest that upward and downward fluid motions are mainly associated with upstream-facing and lee sides of particles, respectively. Results also show that the relative submergence affects the turbulence intensity profiles for vertical velocity over the whole flow depth, while only a weak effect, limited to the near-bed region, is noticed for streamwise velocity component. The approximation of mean velocity profiles with a logarithmic formula reveals that log-profile parameters depend on relative submergence, highlighting inapplicability of a conventional "universal'' logarithmic law for gravel-bed flows with intermediate submergence

To Meet Tomorrow: The Need For Change

Your Advisory Commission recommends to you in the report transmitted herewith that the superior, municipal and justice courts of each county of this state be merged into a single trial court--the countywide superior court. Under this proposed unification, all supporting personnel attached to these new courts (including the clerks, marshals and reporters) would be placed under the exclusive control and supervision of the courts. The new courts would be administered courts and would follow generally uniform procedures and practices. They would be exclusively state financed; therefore, all revenues generated by them, such as fines and filing fees, would go to the state alone. There would be but one class of judges in these courts. The advantages of a completely unified trial court system are many

Microanatomical Structure and Physical Characteristics of Thin Tail Hogget with Calpastatin (CAST-1) Genotype Differences

Thin tail sheep has good adaptation in tropics condition, but they have low meat quality. Quality of thin tail hogget can be improved by selection. Calpastatin (CAST) gene is an indigenous inhibitor of calpain that involved in regulation of protein turn over and growth. The objective of this research was to determine the effect of calpastatin-genotype on microanatomical structure and physical characteristics of thin tail hodget. Nine thin tail sheep from Jonggol were used for this research.PCR-RFLP method was carried out to identify genetic variation of calpastatin gene, based on the identificationof CAST variation genotype. It was found that MM and MN genotypes forcalpastatin gene with TT as asingle Calpain genotype variation. The sheep wasclustered based on the variation of calpastatin gene, 5 sheep hadMM genotype and 4 sheep hadMN genotype. Physical and microanatomical characteristics were analyzed from their meats. Sheep with MN genotype showed tougher meat, it was characterized with a greater of muscle fiber surface area, the number of muscle per muscle bundle and muscle bundle area and harder meat tenderness than in MM genotypes. Hypertrophy and hyperplasia of MN were greater than MM