Numerical modelling of rubber vibration isolators

An important cause for interior noise in vehicles is structure-borne sound from the engine. The vibrations of the source (engine) are transmitted to the receiver structure (the vehicle) causing interior noise in the vehicle. For this reason the engine is supported by rubber isolators for passive isolation in especially the high-frequency region. To make a good judgment of the characteristics of a vibration isolator in the design process, it is useful to use numerical models. In this paper a cylindrical vibration isolator is modelled numerically with the Finite Element package ABAQUS. The investigation is split in two parts: first a nonlinear analysis is performed for different pre-deformations of the mount. After that, a linear harmonic analysis is superimposed on the pre-deformed isolator. The structure-borne sound is transmitted by the isolator by six degrees of freedom, so the harmonic analysis must be performed for different excitations. With the results the behavior of the isolator can be represented by dynamic stiffness matrices as function of the frequency and predeformation. These matrices can be used to model the passive isolation components as part of numerical models of hybrid isolation systems. These isolation systems describe a combination of active and passive isolation to reduce the structure-borne sound transmission to receiver structures

Putting Reciprocity to Work - Positive versus Negative Responses in the Field

We study the role of reciprocity in a labor market field experiment. In a recent paper, Gneezy and List (2006) investigate the impact of gift exchange in this context and find that it has only a transient effect on long run outcomes. Extending their work to examine both positive and negative reciprocity, we find consonant evidence in the positive reciprocity condition: the gift does not work well in the long run (if at all). Yet, in the negative reciprocity treatment we observe much stronger effects: a wage reduction has a significant and lasting negative impact on efforts. Together, these results highlight the asymmetry of positive and negative reciprocity that exists in the field, and provide an indication of the relative importance of each in the long run.reciprocity, gift exchange, field experiment

The currency of reciprocity - gift-exchange in the workplace

What determines reciprocity in employment relations? We conducted a controlled field experiment to measure the extent to which monetary and non-monetary gifts affect workers' performance. We find that nonmonetary gifts have a much stronger impact than monetary gifts of equivalent value. We also observe that when workers are offered the choice, they prefer receiving the money but reciprocate as if they received a nonmonetary gift. This result is consistent with the common saying, 'it's the thought that counts.' We underline this point by showing that also monetary gifts can effectively trigger reciprocity if the employer invests more time and effort into the gift's presentation. --field experiment,reciprocity,gift exchange,non-monetary gifts,in-kind gifts

The quantitative protein interactome in yeast and human

Cellular function is closely tied to protein-protein interactions. Mapping these on a large scale, therefore, provides fundamental knowledge about the regulation and structure of biological systems. With the onset of proteomics, the use of affinity purification coupled to mass spectrometry (MS) has become the major tool to map protein interactions. Already twenty years ago, researchers endeavored to build interaction maps of model organisms such as yeast. However, previous large-scale interaction studies in Saccharomyces cerevisiae date back more than ten years, covered only about half of all genes, and made use of non-quantitative MS and tandem-affinity purification strategies. These approaches were limited by harsh purification protocols and required large amounts of cell lysate. Additionally large false positive and negative rates hampered their use as a fully reliable source for network studies. Building on recent improvements in sensitivity and speed of MS technology and the introduction of the concept of ‘affinity enrichment coupled to MS,’ I developed a fast, robust, and highly reproducible workflow for proteome-wide interaction studies. I applied and optimized the approach for a first full screen in S. cerevisiae. The workflow starts from only a few hundred µg of proteins per pull-down and is performed entirely in 96-well format, including cell growth, lysis, and affinity enrichment of GFP-tagged proteins. To increase sample throughput and minimize MS idle time between injections, I turned to the high throughput Evosep One liquid chromatography system. This allowed me to obtain data on 60 baits per day. The system is coupled online to a timsTOF Pro mass spectrometer capable of fragmenting over 100 peptides per second using the parallel accumulation – serial fragmentation (PASEF) technology. This combination of miniaturization and standardization ensured high sample throughput, sensitivity, and robustness. Altogether, I successfully performed over 4150 pull-downs and completed more than 8300 measurements for the yeast interactome using this next-generation workflow, all in less than 20 weeks of mass spectrometer running time. The dataset has a very high success rate for pull-downs. The near-complete coverage of expressed proteins in our study enabled a novel two-dimensional analysis strategy that efficiently scores interactions. We examined well-known protein complexes, which confirmed very high data quality. Although the yeast interactome has been studied by large-scale methods for decades, the majority of interactions were novel compared to known high-quality interaction databases. Among many striking novel discoveries - I found compelling evidence for interactions between the conserved chromatin remodeler SWI/SNF and SPX-domain-containing plasma-transporters. Using the common GFP-tag for quantification of protein abundance confirmed that our workflow covers a wide range of cellular protein abundances down to a few copies per cell. Redefining the yeast interactome with very high data quality and completeness enabled the study of its fundamental network properties that have been controversially discussed over many years. In total, our protein-protein interaction network encompasses about 4,000 proteins connected via about 30,000 interactions. A full browsable web application is accessible at yeast-interactome.org and allows (sub-) network exploration, interactor validation via volcano plots and correlation maps, and sample quality control. In a collaboration with the CZ Biohub, we set out to implement the mass spectrometry pipeline developed here to an interaction screen with CRISPR GFP-tagged human HEK293T cells. The reduced sample amount allowed us to screen cell cultures grown in 12-well plates for high throughput. The interaction and localization results of 1,311 processed interactomes in biological triplicates can be accessed at opencell.czbiohub.org

Navigating clues to success in academia

Academic success and how to achieve it takes diverse forms, depending on who’s asked. We suggest that happiness, impact, and longevity can be achieved with professional effort and support that balances the toil and joys of one’s chosen path.<br/

Impact of aerosol particles on measured and simulated polarized solar radiation

Solar radiation scattered within the atmosphere by atmospheric particles and aerosol particles has been investigated with regard to their state of polarization. Therefore measurements are performed with the COmpact RAdiation measurement System CORAS to analyze the individual components of the Stokes vector describing the measured radiation. For this purpose new optical inlets including a polarization filter have been developed. In parallel, radiative transfer simulations are conducted to interpret the measurements. For this purpose, two different radiative transfer solvers (SCIATRAN and polRadtran) were used. The simulations have been compared with the measurements to characterize the aerosol optical thickness and the predominant aerosol type

Multilevel Contracts for Trusted Components

This article contributes to the design and the verification of trusted components and services. The contracts are declined at several levels to cover then different facets, such as component consistency, compatibility or correctness. The article introduces multilevel contracts and a design+verification process for handling and analysing these contracts in component models. The approach is implemented with the COSTO platform that supports the Kmelia component model. A case study illustrates the overall approach.Comment: In Proceedings WCSI 2010, arXiv:1010.233

Dust-temperature of an isolated star-forming cloud: Herschel observations of the Bok globule CB244

We present Herschel observations of the isolated, low-mass star-forming Bok globule CB244. It contains two cold sources, a low-mass Class 0 protostar and a starless core, which is likely to be prestellar in nature, separated by 90 arcsec (~ 18000 AU). The Herschel data sample the peak of the Planck spectrum for these sources, and are therefore ideal for dust-temperature and column density modeling. With these data and a near-IR extinction map, the MIPS 70 micron mosaic, the SCUBA 850 micron map, and the IRAM 1.3 mm map, we model the dust-temperature and column density of CB244 and present the first measured dust-temperature map of an entire star-forming molecular cloud. We find that the column-averaged dust-temperature near the protostar is ~ 17.7 K, while for the starless core it is ~ 10.6K, and that the effect of external heating causes the cloud dust-temperature to rise to ~ 17 K where the hydrogen column density drops below 10^21 cm^-2. The total hydrogen mass of CB244 (assuming a distance of 200 pc) is 15 +/- 5 M_sun. The mass of the protostellar core is 1.6 +/- 0.1 M_sun and the mass of the starless core is 5 +/- 2 M_sun, indicating that ~ 45% of the mass in the globule is participating in the star-formation process.Comment: Accepted for A&A Herschel Special Issue; 5 pages, 2 figure