Waterproof sensor system for simultaneous pressure and hot-film flow measurements

For simultaneous measurement of pressure and near surface flow conditions allowing indirect determination of wall shear stress in experimental water tunnel environment an integrated hybrid sensor system has been developed. In contrast to known approaches, which are limited to the use in gas atmosphere due to protruding electrical and fragile parts, our sensor system is waterproof shielded and embedded in epoxy resin. Furthermore an amplification circuit for the pressure signal based on a programmable gain amplifier is integrated in direct vicinity to the pressure sensor in order to minimize noise by electromagnetic disturbances. Also sensor systems with on-board digitalization of the pressure signal for direct digital read-out were realized. We present all aspects of system assembly and embedding to one waterproof module. Furthermore, read-out strategies as well as sensor test results in air and water are shown and watertightness is confirmed

Microgrippers to handle Organoids and pancreatic Islets for Precision Measurements of biological Function

The model of the cultured single cell is considered insufficient to explain the physiological regulation taking place at the organ level. The same is true for the prediction of drug action at the organ level or at the level of the intact organism. For these reasons 3D cell culture models are in increasing demand. It is thus necessary to develop the instruments to handle such cell aggregates and organoids in a controlled, precise and gentle manner. Here, a microgripper is presented which is able to work in aqueous solutions and which is compatible with electrophysiological recordings of the cells immobilized by it. It was successfully employed to position isolated pancreatic islets and a 3D cell culture model of insulin-secreting cells, the so-called MIN6-pseudoislet. As required it was possible to measure the membrane potential of cells within these aggregates without any interference from the microgripper

A Disposable Pneumatic Microgripper for Cell Manipulation with Image-Based Force Sensing

A new design for a single-use disposable pneumatic microgripper is presented in this paper. It enables very cost-eective batch microfabrication in SU-8 with a single lithography mask by shifting manufacturing complexity into reusable components. An optically readable force sensor with potential to be used in a feedback loop has been integrated in order to enable gripping with a controlled force. The sensors are first examined separately from the gripper and exhibit good linearity. The gripper function utilizes the disposable gripper element together with a reusable gripper fixture. During experiments, the pneumatically actuated microgripper can vary the gripping force within a range of a few mN (up to 5.7 mN was observed). This microgripper is planned to be used in a liquid environment for gripping larger aggregates of cells in combination with the patch clamp technique. This approach will allow Langerhans islets suspended in an electrolyte solution to be grasped and held during electrophysiological measurements without cell damage

Entwicklung eines integrierten multifunktionalen Fluoreszenzdetektors

Fluoreszenzdetektion hat eine große Bedeutung in biologischen und medizinischen Anwendungen für die Analyse verschiedener Farbstoffe und Zellkulturen. Durch Kombination von Fluidik, Optik und Elektronik ist die Realisierung eines kompakten und hochempfindlichen Messsystems möglich, welches vorteilhaft bei der Messung von Proben mit kleinen Volumina ist

SDM:A New Data Set on Self-determination Movements with an Application to the Reputational Theory of Conflict

This dataset, of self-determination movements (SDMs) with universal coverage for the period from 1945 to 2012, corrects the selection bias that characterizes previous efforts to code SDMs and significantly expands coverage relative to the extant literature. For a random sample of cases, we add information on state–movement interactions and several attributes of SDM groups. The data can be used to study the causes of SDMs, the escalation of self-determination (SD) conflicts over time, and several other theoretical arguments concerning separatist conflict that have previously been tested with incomplete or inferior data.The creators request that the associated paper is cited in place of this dataset

Pre-Election Positions and Voting Behaviour in Parliament: Consistency among Swiss MPs

This article examines the determinants of positional incongruence between pre-election statements and post-election behaviour in the Swiss parliament between 2003 and 2009. The question is examined at the individual MP level, which is appropriate for dispersion-of-powers systems like Switzerland. While the overall rate of political congruence reaches about 85%, a multilevel logit analysis detects the underlying factors which push or curb a candidate's propensity to change his or her mind once elected. The results show that positional changes are more likely when (1) MPs are freshmen, (2) individual voting behaviour is invisible to the public, (3) the electoral district magnitude is not small, (4) the vote is not about a party's core issue, (5) the MP belongs to a party which is located in the political centre, and (6) if the pre-election statement dissents from the majority position of the legislative party group. Of these factors, the last one is paramount

SDM: A New Dataset on Self-Determination Movements with an Application to the Reputational Theory of Conflict

This article presents a new data set on self-determination movements (SDMs) with universal coverage for the period from 1945 to 2012. The data set corrects the selection bias that characterizes previous efforts to code SDMs and significantly expands coverage relative to the extant literature. For a random sample of cases, we add information on state–movement interactions and several attributes of SDM groups. The data can be used to study the causes of SDMs, the escalation of self-determination (SD) conflicts over time, and several other theoretical arguments concerning separatist conflict that have previously been tested with incomplete or inferior data. We demonstrate the usefulness of the new data set by revisiting Barbara Walter’s influential argument that governments will not accommodate SD challengers if they face several potential future challengers down the road because they want to build a reputation for strength. We do not find support for Walter’s reputational theory of separatist conflict.status: publishe

Quantification and monosaccharide composition of hemicelluloses from different plant functional types

Hemicelluloses are the second most abundant polysaccharide in nature after cellulose. So far, thechemical heterogeneity of cell-wall hemicelluloses and the relatively large sample-volume required inexisting methods represent major obstacles for large-scale, cross-species analyses of this important plant compound. Here, we apply a new micro-extraction method to analyse hemicelluloses and the ratioof ‘cellulose and lignin’ to hemicelluloses in different tissues of 28 plant species comprising fourplant functional types (broad-leaved trees, conifers, grasses and herbs). For this study, the fiber analysisafter Van Soest was modified to enable the simultaneous quantitative and qualitative measurements ofhemicelluloses in small sample volumes. Total hemicellulose concentrations differed markedly amongfunctional types and tissues with highest concentration in sapwood of broad-leaved trees (31% d.m.in Fraxinus excelsior) and lowest concentration between 10 and 15% d.m. in leaves and bark of woodyspecies as well as in roots of herbs. As for total hemicellulose concentrations, plant functional types and tissues exhibited characteristic ratios between the sum of cellulose plus lignin and hemicelluloses, with very high ratios (2) in all investigated leaves. Additional HPLC analyses of hydrolysed hemicelluloses showed xylose to be the dominant hemicellulose monosaccharide in tissues of broad-leaved trees, grasses and herbs while coniferous species showed higher amounts of arabinose, galactose and mannose. Overall, the micro-extraction method permitted for the simultaneous determination of hemicelluloses of various tissues and plant functional types which exhibited characteristic hemicellulose concentrations and monosaccharide patterns