Supersaturated dispersions of rod-like viruses with added attraction

The kinetics of isotropic-nematic (I-N) and nematic-isotropic (N-I) phase transitions in dispersions of rod-like {\it fd}-viruses are studied. Concentration quenches were applied using pressure jumps in combination with polarization microscopy, birefringence and turbidity measurements. The full biphasic region could be accessed, resulting in the construction of a first experimental analogue of the bifurcation diagram. The N-I spinodal points for dispersions of rods with varying concentrations of depletion agents (dextran) were obtained from orientation quenches, using cessation of shear flow in combination with small angle light scattering. We found that the location of the N-I spinodal point is independent of the attraction, which was confirmed by theoretical calculations. Surprisingly, the experiments showed that also the absolute induction time, the critical nucleus and the growth rate are insensitive of the attraction, when the concentration is scaled to the distance to the phase boundaries.Comment: 13 pages, 14 figures. accepted in Phsical Review

Explaining Success and Failure in the Commons: The Configural Nature of Ostrom’s Institutional Design Principles

Governing common pool resources (CPR) in the face of disturbances such as globalization and climate change is challenging. The outcome of any CPR governance regime is the influenced by local combinations of social, institutional, and biophysical factors, as well as cross-scale interdependencies. In this study, we take a step towards understanding multiple-causation of CPR outcomes by analyzing 1) the co-occurrence of Destign Principles (DP) by activity (irrigation, fishery and forestry), and 2) the combination(s) of DPs leading to social and ecological success. We analyzed 69 cases pertaining to three different activities: irrigation, fishery, and forestry. We find that the importance of the design principles is dependent upon the natural and hard human made infrastructure (i.e. canals, equipment, vessels etc.). For example, clearly defined social bounduaries are important when the natural infrastructure is highly mobile (i.e. tuna fish), while monitoring is more important when the natural infrastructure is more static (i.e. forests or water contained within an irrigation system). However, we also find that congruence between local conditions and rules and proportionality between investment and extraction are key for CPR success independent from the natural and human hard made infrastructure. We further provide new visualization techniques for co-occurrence patterns and add to qualitative comparative analysis by introducing a reliability metric to deal with a large meta-analysis dataset on secondary data where information is missing or uncertain

An iterative approach to Large-N case studies: insights from qualitative analysis of quantitative inconsistencies

Large-N comparative studies have helped common pool resource scholars gain general insights into the factors that influence collective action and governance outcomes. However, these studies are often limited by missing data, and suffer from the methodological limitation that important information is lost when we reduce textual information to quantitative data. This study was motivated by nine case studies that appeared to be inconsistent with the expectation that the presence of Ostrom’s Design Principles increases the likelihood of successful common pool resource governance. These cases highlight the limitations of coding and analysing Large-N case studies. We examine two issues: 1) the challenge of missing data and 2) potential approaches that rely on context (which is often lost in the coding process) to address inconsistencies between empirical observations theoretical predictions. For the latter, we conduct a post-hoc qualitative analysis of a large-N comparative study to explore 2 types of inconsistencies: 1) cases where evidence for nearly all design principles was found, but available evidence led to the assessment that the CPR system was unsuccessful and 2) cases where the CPR system was deemed successful despite finding limited or no evidence for design principles. We describe inherent challenges to large-N comparative analysis to coding complex and dynamically changing common pool resource systems for the presence or absence of design principles and the determination of “success”. Finally, we illustrate how, in some cases, our qualitative analysis revealed that the identity of absent design principles explained inconsistencies hence de-facto reconciling such apparent inconsistencies with theoretical predictions. This analysis demonstrates the value of combining quantitative and qualitative analysis, and using mixed-methods approaches iteratively to build comprehensive methodological and theoretical approaches to understanding common pool resource governance in a dynamically changing context

Challenges and Opportunities in Coding the Commons: Problems, Procedures, and Potential Solutions in Large-N Comparative Case Studies

On-going efforts to understand the dynamics of coupled social-ecological (or more broadly, coupled infrastructure) systems and common pool resources have led to the generation of numerous datasets based on a large number of case studies. This data has facilitated the identification of important factors and fundamental principles which increase our understanding of such complex systems. However, the data at our disposal are often not easily comparable, have limited scope and scale, and are based on disparate underlying frameworks inhibiting synthesis, meta-analysis, and the validation of findings. Research efforts are further hampered when case inclusion criteria, variable definitions, coding schema, and inter-coder reliability testing are not made explicit in the presentation of research and shared among the research community. This paper first outlines challenges experienced by researchers engaged in a large-scale coding project; then highlights valuable lessons learned; and finally discusses opportunities for further research on comparative case study analysis focusing on social-ecological systems and common pool resources

Comparison investigations of CMM accuracy tests by different length gauges

Przeprowadzono badania, mające na celu sprawdzenie możliwości zastosowania nowej metody sprawdzania dokładności współrzędnościowych maszyn pomiarowych (CMM) w odniesieniu do metody klasycznej. W nowej metodzie dokładność CMM określana jest na podstawie pomiaru przemieszczenia elementu optycznego wchodzącego zarazem w skład układu interferometru laserowego. Zastosowanie interferometru pozwala na sprawdzenie dokładności CMM na dowolnie długich odcinkach pomiarowych w przeciwieństwie do obecnie używanych wzorców końcowych tzn. płytek wzorcowych, których długość nie przekracza jednego metra.The conception of an accuracy test for Coordinate Measuring Machine with use of a laser interferometer is presented. In this method [1, 2] the CMM accuracy is evaluated basing on the displacement of an optics element (Fig. 1.) which is a part of the interferometer system. Interferometer allows checking the CMM accuracy along an unlimited distance in contrary to the most popular gauge blocks which are no longer than one meter. A cube corner fixed in the special adapter (Fig. 2.) was used as an artifact. Repeatability of measurements of the cube corner was checked on CMM ACCURA made by C.Zeiss manufacturer, CMM was equipped with a VAST Gold central head probe. The measurement results of the reference sphere and cube corner are shown in Fig. 3. The experiment results confirm that a cube corner can be used as the measurement artifact for coordinates measuring machines. It also works very well as a mirror in the interferometer system. The cube corner measurement repeatability (0.2 žm) is similar to that reached during measurements of the reference sphere (0.4 žm). The methods was also checked during the accuracy test for the ZEISS ACCURA CMM. The results are presented in Fig. 4. The differences between the measurements of the gauge block and cube corner change from -0.8 to 0.6 žm. In the future research it will be important to assess all factors which can influence the accuracy of this method during the CMM length measurement test

SANS and dynamic light scattering to investigate the viscosity of toluene under high pressure up to 1800 bar

We present a joint experimental study of small angle neutron scattering (SANS) and dynamic light scattering (DLS) under high pressures up to 1800 bar on a colloidal suspension, which consists of a core-shell system made of sterically stabilized silica particles grafted with octadecyl chains in toluene. From the analysis of SANS contrast variation under pressure, we could estimate the amount of compression in both core and shell under the action of pressure. The DLS measurements under pressure yield a diffusion coefficient which enabled us together with the SANS result to evaluate the pressure-dependent viscosity of the dilute suspension which is to a good approximation the solvent viscosity on the basis of the Stokes-Einstein relation. The excellent comparison of the so-calculated pressure-dependent viscosities of toluene with literature values demonstrates the value of our method to measure viscosities under pressure

Web analytics combined with eye tracking for successful user experience design: a case study

The authors propose a new approach for the mobile user experience design process by means of web analytics and eye-tracking. The proposed method was applied to design the LUT mobile website. In the method, to create the mobile website design, data of various users and their behaviour were gather-ed and analysed using the web analytics tool. Next, based on the findings from web analytics, the mobile prototype for the website was created and validated in eye-tracking usability testing. The analysis of participants’ behaviour during eye-tracking sessions allowed improvements of the prototype

Structure and phase diagram of an adhesive colloidal dispersion under high pressure: A small angle neutron scattering, diffusing wave spectroscopy, and light scatttering study

We have applied small angle neutron scattering (SANS), diffusing wave spectroscopy (DWS), and dynamic light scattering (DLS) to investigate the phase diagram of a sterically stabilized colloidal system consisting of octadecyl grafted silica particles dispersed in toluene. This system is known to exhibit gas-liquid phase separation and percolation, depending on temperature T, pressure P, and concentration phi. We have determined by DLS the pressure dependence of the coexistence temperature and the spinodal temperature to be dP/dT=77 bar/K. The gel line or percolation limit was measured by DWS under high pressure using the condition that the system became nonergodic when crossing it and we determined the coexistence line at higher volume fractions from the DWS limit of turbid samples. From SANS measurements we determined the stickiness parameter tau(B)(P,T,phi) of the Baxter model, characterizing a polydisperse adhesive hard sphere, using a global fit routine on all curves in the homogenous regime at various temperatures, pressures, and concentrations. The phase coexistence and percolation line as predicted from tau(B)(P,T,phi) correspond with the determinations by DWS and were used to construct an experimental phase diagram for a polydisperse sticky hard sphere model system. A comparison with theory shows good agreement especially concerning the predictions for the percolation threshold. From the analysis of the forward scattering we find a critical scaling law for the susceptibility corresponding to mean field behavior. This finding is also supported by the critical scaling properties of the collective diffusion

An analysis of the effect of impact loading on the destruction of vascular structures in the brain

Subdural hematomas are one of the frequent complications of head injuries. Such hematomas result from exceeding the border strength values of bridging veins. Subdural haemorrhages are life-threatening and are a frequent cause of considerable pathologies. Traffic participants and also soldiers who participate in armed conflicts are the most vulnerable to head injuries. Although hematomas have been studied for many years the mechanism of hematoma formation has not been fully clarified as yet. In the paper, the effort of brain tissue structures due to the propagation of shock wave was analyzed. Particular attention was paid to the deformation ability and changes in the energy of bridging veins. This research was concerned with changes in mechanical properties of these veins in the frontal, parietal and occipital regions of the brain. For the present research the authors have constructed finite element models of brain tissue fragments and conducted numerical studies taking into account the boundary conditions arising from violent overloads that result from combat operations. As a result of the numerical analysis conducted, critical values of strain and stress have been obtained. The analysis showed high diversity in the properties of the different regions of the brain tissue. The studies carried out by the authors rendered it possible to assess the effort of the tissue structures of veins in connection with mechanical parameters, including geometrical parameters, in particular in relation to the likelihood of hematoma formation