Negative and Nonlinear Response in an Exactly Solved Dynamical Model of Particle Transport

We consider a simple model of particle transport on the line defined by a dynamical map F satisfying F(x+1) = 1 + F(x) for all x in R and F(x) = ax + b for |x| < 0.5. Its two parameters a (`slope') and b (`bias') are respectively symmetric and antisymmetric under reflection x -> R(x) = -x. Restricting ourselves to the chaotic regime |a| > 1 and therein mainly to the part a>1 we study not only the `diffusion coefficient' D(a,b), but also the `current' J(a,b). An important tool for such a study are the exact expressions for J and D as obtained recently by one of the authors. These expressions allow for a quite efficient numerical implementation, which is important, because the functions encountered typically have a fractal character. The main results are presented in several plots of these functions J(a,b) and D(a,b) and in an over-all `chart' displaying, in the parameter plane, all possibly relevant information on the system including, e.g., the dynamical phase diagram as well as invariants such as the values of topological invariants (kneading numbers) which, according to the formulas, determine the singularity structure of J and D. Our most significant findings are: 1) `Nonlinear Response': The parameter dependence of these transport properties is, throughout the `ergodic' part of the parameter plane (i.e. outside the infinitely many Arnol'd tongues) fractally nonlinear. 2) `Negative Response': Inside certain regions with an apparently fractal boundary the current J and the bias b have opposite signs.Comment: corrected typos and minor reformulations; 28 pages (revtex) with 7 figures (postscript); accepted for publication in JS

Patterns of transition. Female native Dutch and ethnic minority employment patterns in the Dutch labour market, 1991 and 2002

This study analyses female native Dutch and ethnic minority employment patterns in the Dutch labour market. Focusing on life-course employment patterns, it aims to find out if native Dutch and ethnic minority women in the Netherlands have undergone a transition towards more labour market participation between 1991 and 2002. Three patterns of change in employment integration by age can be discerned. First, increasing employment levels for native Dutch women of almost all age groups, but in particular for those age groups that have to combine employment with rearing children. Second, a high employment level for Surinamese and Antillean women, revealing strong employment integration of all age groups, so that combining market work and rearing children does not hamper labour market integration. Third, a more traditional pattern for Turkish and Moroccan women, yet indicating an increased employment rate for almost all age groups, in particular 20-24 years. We find that critical life events such as motherhood have different effects on employment for Mediterranean, Caribbean and native Dutch women. In addition, the analysis shows that the attachment of both native Dutch and ethnic minority women to the labour market becomes stronger, and the influence of motherhood becomes smaller, over time. All in all, Caribbean women are the most attached to the labour market. © 2006 Taylor & Francis

Comb-drive actuators for large displacements

The design, fabrication and experimental results of lateral-comb-drive actuators for large displacements at low driving voltages is presented. A comparison of several suspension designs is given, and the lateral large deflection behaviour of clamped - clamped beams and a folded flexure design is modelled. An expression for the axial spring constant of folded flexure designs including bending effects from lateral displacements, which reduce the axial stiffness, is also derived. The maximum deflection that can be obtained by comb-drive actuators is bounded by electromechanical side instability. Expressions for the side-instability voltage and the resulting displacement at side instability are given. The electromechanical behaviour around the resonance frequency is described by an equivalent electric circuit. Devices are fabricated by polysilicon surface micromachining techniques using a one-mask fabrication process. Static and dynamic properties are determined experimentally and are compared with theory. Static properties are determined by displacement-to-voltage, capacitance-to-voltage and pull-in voltage measurements. Using a one-port approach, dynamic properties are extracted from measured admittance plots. Typical actuator characteristics are deflections of about at driving voltages around 20 V, a resonance frequency around 1.6 kHz and a quality factor of approximately 3

SLIP: 10 years ago and 10 years from now

Founded in 1999, the ACM SLIP Workshop is now in its 12th year. The 2010 SLIP Panel session will highlight perspectives from three individuals who have had great influence on the course of SLIP, and provide an opportunity for lively discussion by workshop attendees of prospects for the next 10 years of SLIP. This panel summary records preliminary thoughts of the panelists on two starting questions

Immune modulation by fish kinetoplastid parasites : a role for nitric oxide

Trypanoplasma borreli and Trypanosoma carassii are kinetoplastid parasites infecting cyprinid fish. We investigated the role of nitric oxide (NO) in immune modulation during T. borreli and T. carassii infection of carp. Phagocytic cells from different organs produced NO and serum nitrate levels increased, demonstrating that T. borreli activates NO production in vivo. In contrast, T. carassii did not induce NO production in vivo and inhibited LPS-induced NO production in vitro. Production of NO was detrimental to the host as T. borreli-infected carp treated with the inducible NO synthase inhibitor aminoguanidine had a higher survival than infected control carp. This detrimental effect can be explained (in part) by the toxicity of NO to cells in vitro as NO inhibited the proliferative response of blood and spleen leukocytes. Head-kidney phagocytes were resistant to the immunosuppressive effects of NO in vitro. The NO-inducing activity of T. borreli may be an adaptation developed to ensure survival and immune evasion in the fish host. Apparently, T. carassii has adopted another strategy by deactivating specific functions of phagocytes. Both strategies may ensure long-term survival of the parasite

Literature review on pickling inhibitors and cadmium electroplating processes

Because introduction of hydrogen during bright-cadmium electroplating of high strength steels causes hydrogen-stress cracking, a program was undertaken to evaluate various processes and materials. Report describes effectiveness of inhibitors for reducing hydrogen absorption by steels

Study to minimize hydrogen embrittlement of ultrahigh-strength steels

Hydrogen-stress cracking in high-strength steels is influenced by hydrogen content of the material and its hydrogen absorption tendency. Non-embrittling cleaning, pickling, and electroplating processes are being studied. Protection from this hydrogen embrittlement is important to the aerospace and aircraft industries

Using a Flow Through device to reconstruct the thermal gradient in the water column based on G. inflata Mg/Ca

We present Mg/Ca analyses performed via a Flow Through sequential dissolution device connected to an ICP-OES on the planktonic foraminifer Globorotalia inflata. The aim of the study is to explore the possibility to reconstruct the thermal gradient in the water column by separating non-crusted and crusted calcite phases in the tests of G. inflata using the difference between their Mg/Ca ratios as a measure of the thermal gradient. An important assumption is that the non-crusted part of the tests is calcified in shallow, warmer water than the crusted part. For analyses a range of different preparation steps were used to determine the ideal way of separating the phases. Foraminifer tests were (not) cleaned, (not) crushed, and (not) pulverized before online analysis with the FT device. To analyze samples with a FT device the foraminifer tests are placed on a filter with a mesh of 0.45 μm preventing clay minerals to wash through. A sequential dissolution protocol first rinses the samples with buffered Seralpur water before QD HNO3 is added in small steps to create a ramp of increasing acid strength. As acid is kept constant at each concentration for several minutes, dissolution of a specific calcite phase can take place. Initial results show that it is most effective to slightly crush the tests without applying standard cleaning procedures, but rather analyze them without cleaning. Samples were selected from the South Atlantic (core tops and specific downcore samples) and the Mediteterranean (plankton tows). All samples were chosen based on previous work on them to provide comparison with routinely analysed Mg/Ca ratios. The South Atlantic samples have been analyzed extensively as bulk samples separated in difference size fractions and crusted vs. non-crusted (Groeneveld and Chiessi). The Mediterranean samples were not only analyzed as bulk samples but also by Laser Ablation ICP-MS (von Raden et al.). Results show that bulk analyses are reliably reproduced by the FT method, especially for samples which are dominated by crusted calcite. Samples which were uncrusted often gave much higher Mg/Ca ratios than the bulk analyses. These higher Mg/Ca ratios mainly occur in the plankton tow samples and were also identified with Laser Ablation ICP-MS. A possible reason for this could be the presence of a high Mg amorphous calcite layer on the outside of foraminifer tests which have not completed their calcification yet as was recently also pointed out in several other studies. Identification of the crusted and uncrusted phases, and therewith a thermal gradient, seems to give the expected differences but a more rigorous statistical treatment is needed to pinpoint singular dissolution phases

MolabIS - An integrated information system for storing and managing molecular genetics data

BACKGROUND: Long-term sample storage, tracing of data flow and data export for subsequent analyses are of great importance in genetics studies. Therefore, molecular labs do need a proper information system to handle an increasing amount of data from different projects. RESULTS: We have developed a molecular labs information management system (MolabIS). It was implemented as a web-based system allowing the users to capture original data at each step of their workflow. MolabIS provides essential functionality for managing information on individuals, tracking samples and storage locations, capturing raw files, importing final data from external files, searching results, accessing and modifying data. Further important features are options to generate ready-to-print reports and convert sequence and microsatellite data into various data formats, which can be used as input files in subsequent analyses. Moreover, MolabIS also provides a tool for data migration. CONCLUSIONS: MolabIS is designed for small-to-medium sized labs conducting Sanger sequencing and microsatellite genotyping to store and efficiently handle a relative large amount of data. MolabIS not only helps to avoid time consuming tasks but also ensures the availability of data for further analyses. The software is packaged as a virtual appliance which can run on different platforms (e.g. Linux, Windows). MolabIS can be distributed to a wide range of molecular genetics labs since it was developed according to a general data model. Released under GPL, MolabIS is freely available at http://www.molabis.org

Escapement of the Cape rock lobster (Jasus lalandii ) through the mesh and entrance of commercial traps

Metal-framed traps covered with polyethylene mesh used in the fishery for the South African Cape rock lobster (Jasus lalandii) incidentally capture large numbers of undersize (<75 mm CL) specimens. Air-exposure, handling, and release procedures affect captured rock lobsters and reduce the productivity of the stock, which is heavily fished. Optimally, traps should retain legalsize rock lobsters and allow sublegal animals to escape before traps are hauled. Escapement, based on lobster morphometric measurements, through meshes of 62 mm, 75 mm, and 100 mm was investigated theoretically under controlled conditions in an aquarium, and during field trials. SELECT models were used to model escapement, wherever appropriate. Size-selectivity curves based on the logistic model fitted the aquarium and field data better than asymmetrical Richards curves. The lobster length at 50% retention (L50) on the escapement curve for 100-mm mesh in the aquarium (75.5 mm CL) approximated the minimum legal size (75 mm CL); however estimates of L50 increased to 77.4 mm in field trials where trapentrances were sealed, and to 82.2 mm where trap-entrances were open. Therfore, rock lobsters that cannot escape through the mesh of sealed field traps do so through the trap entrance of open traps. By contrast, the wider selection range and lower L25 of field, compared to aquarium, trials (SR = 8.2 mm vs. 2.6 mm; L25 =73.4 mm vs. 74.1 mm), indicate that small lobsters that should be able to escape from 100-mm mesh traps do not always do so. Escapement from 62-mm mesh traps with open entrance funnels increased by 40−60% over sealed traps. The findings of this study with a known size distribution, are related to those of a recent indirect (comparative) study for the same species, and implications for trap surveys, commercial catch rates, and ghost fishing are discussed