962 research outputs found
Benefit reentitlement conditions in unemployment insurance schemes
Unemployment insurance schemes include conditions on past employment history as part of the eligibility conditions. This aspect is often neglected in the literature which primarily focuses on benefit levels and benefit duration. In a search-matching framework we show that benefit duration and employment requirements are substitute instruments in affecting job search incentives and thus gross unemployment. We analyse the optimal design of the unemployment insurance system (benefit levels, duration and employment requirements) under a utilitarian social welfare function. Simulations show that a higher insurance motive captured by more risk aversion implies higher benefit generosity and more lax employment requirements but also shortened benefit duration
Benefit Reentitlement Conditions in Unemployment Insurance Schemes
Unemployment insurance schemes include conditions on past employment history as part of the eligibility conditions. This aspect is often neglected in the literature which primarily focuses on benefit levels and benefit duration. In a search-matching framework we show that benefit duration and employment requirements are substitute instruments in affecting job search incentives and thus gross unemployment. We analyse the optimal design of the unemployment insurance system (benefit levels, duration and employment requirements) under a utilitarian social welfare function. Simulations show that a higher insurance motive captured by more risk aversion implies higher benefit generosity and more lax employment requirements but also shortened benefit duration
Geochemistry and geochronology of mafic rocks from the Spanish Central System: Constraints on the mantle evolution beneath central Spain
The Spanish Central System (SCS) contains several suites of Palaeozoic mafic igneous intrusions with contrasting geochemical affinity: Ordovician tholeiitic metabasites, Variscan calc-alkaline gabbros (Gb1) and microdiorites (Gb2), shoshonitic monzogabbros (Gb3) and alkaline diabases and lamprophyres (Gb4). Not all of these rocks are accurately dated, and several aspects of their genesis are still poorly understood. We present new whole-rock geochemical data (major and trace elements, and SrâNd isotopes), UâPb and LuâHf isotopic ratios on magmatic zircons and 40Ar/39Ar amphibole geochronology results in order to establish a precise chronology for the successive events of magmatism in the SCS, and discuss the nature of their mantle sources. Accurate ages have been determined for the Variscan gabbros (305â294 âMa), the microdiorites (299 âMa) and the accompanying felsic porphyries (292 âMa), the shoshonitic monzogabbros (285 âMa), and the alkaline diabases (274 âMa) and monzosyenites (271â264 âMa). According to this information, the Variscan mafic magmatism would be mainly concentrated in the range of 305â294 âMa, with a final manifestation represented by the minor shoshonitic dykes. The alkaline magmatism proved to be slightly older than previously thought and yielded at least two distinct pulses: diabases and lamprophyresâmonzosyenites. Zircon Hf isotopes evidence the involvement of depleted and slightly enriched mantle sources. The bulk of the ÎľHf values are in the broad range of â8 to +11, indicative of melting both depleted and enriched mantle regions. The high within-sample Hf isotope variation (up to ~11 epsilon units) shown by samples from the Variscan series (gabbros, microdiorites and monzogabbros) could be explained mainly by hybridisation of magmas derived from heterogeneous lithospheric mantle sources. Pressure estimates indicate that the Variscan mafic magmas were extracted from the lithosphere. The NdâHf isotopic composition of these suites of rocks suggests the recycling of pelitic sediments during the Cadomian orogeny. Deeper (asthenospheric) mantle levels were involved in the generation of the alkaline suite, whose anomalous negative ÎľHf values (moderately decoupled with respect to radiogenic Nd) could be associated with subducted oceanic components raised by mantle upwelling associated with lithosphere thinning and extension during the Permian
Sediment microbial taxonomic and functional diversity in a natural salinity gradient challenge Remaneâs âspecies minimumâ concept
Several models have been developed for the description of diversity in estuaries and other brackish habitats, with the most recognized being Remane's Artenminimum (``species minimum'') concept. It was developed for the Baltic Sea, one of the world's largest semi-enclosed brackish water body with a unique permanent salinity gradient, and it argues that taxonomic diversity of macrobenthic organisms is lowest within the horohalinicum (5 to 8 psu). The aim of the present study was to investigate the relationship between salinity and sediment microbial diversity at a freshwater-marine transect in Amvrakikos Gulf (Ionian Sea, Western Greece) and assess whether species composition and community function follow a generalized concept such as Remane's. DNA was extracted from sediment samples from six stations along the aforementioned transect and sequenced for the 16S rRNA gene using high-throughput sequencing. The metabolic functions of the OTUs were predicted and the most abundant metabolic pathways were extracted. Key abiotic variables, i.e., salinity, temperature, chlorophyll-a and oxygen concentration etc., were measured and their relation with diversity and functional patterns was explored. Microbial communities were found to differ in the three habitats examined (river, lagoon and sea) with certain taxonomic groups being more abundant in the freshwater and less in the marine environment, and vice versa. Salinity was the environmental factor with the highest correlation to the microbial community pattern, while oxygen concentration was highly correlated to the metabolic functional pattern. The total number of OTUs showed a negative relationship with increasing salinity, thus the sediment microbial OTUs in this study area do not follow Remane's concept
Rapid sample preparation and low-resource molecular detection of hepatopancreatic parvoviruses (HPV) by recombinase polymerase amplification lateral flow detection assay in shrimps (Fenneropenaeus merguiensis)
Background Viral diseases are a major problem in shrimp aquaculture facilities as these diseases reduce growth rates, which inevitably lead to production and profit losses. Hepatopancreatic parvoviruses (HPV) are common diseases in shrimp that appear to be associated with high or low levels of replication in specific genetic lineages. Selective breeding may result in resistance to HPV and improved body traits such as body weight, meat yield and shrimp colour, facilitating shrimp farming. HPV virus titre is commonly determined by quantitative PCR (qPCR), which is a time-consuming method requiring laboratory equipment unsuitable for field implementation. The aim of this study was to develop a simple, robust, rapid and reliable method to detect HPV in low-resource environments. Methods We developed a rapid shrimp HPV test that uses (1) a simple three-step sample preparation protocol, followed by (2) isothermal recombinase polymerase amplification (RPA) and lateral flow strip detection (LFD). Analytical sensitivity testing was performed in a background banana shrimp sample matrix, and retrospective testing of Fenneropenaeus merguiensis hepatopancreas tissues (n = 33) with known qPCR viral titres was used to determine diagnostic sensitivity and specificity. Results The rapid shrimp HPV test could detect as little as 35 genome-equivalent copies per reaction in homogenized F. merguiensis banana shrimp. Retrospective testing of stored tissues (n = 33) indicated 100% diagnostic sensitivity (95% confidence interval, CI: 86â100%) and 100% specificity (95% CI: 66â100%) for detection of HPV. Conclusion The rapid shrimp HPV test could be completed in only 40 minutes, and required only homogenization pestles, some pipettors, and a small heating block for single temperature incubation at 39°C. Critically, our procedure eliminated the time-consuming purification of nucleic acids from samples and when combined with RPA-LFD offers a user-friendly HPV detection format that can potentially be performed on-site. Our approach represents a major step forward in the development of a simple and sensitive end-point method for quick determination of unfavourable HPV virus numbers in shrimp, and has great potential to advance on-site management of shrimps in aquaculture
Speckle contrast optical tomography: A new method for deep tissue three-dimensional tomography of blood flow
A novel tomographic method based on the laser speckle contrast, speckle contrast optical tomography (SCOT) is introduced that allows us to reconstruct three dimensional distribution of blood flow in deep tissues. This method is analogous to the diffuse optical tomography (DOT) but for deep tissue blood flow. We develop a reconstruction algorithm based on first Born approximation to generate three dimensional distribution of flow using the experimental data obtained from tissue simulating phantoms
Exploring the relationship between EMG feature space characteristics and control performance in machine learning myoelectric control
In myoelectric machine learning (ML) based control, it has been demonstrated that control performance usually increases with training, but it remains largely unknown which underlying factors govern these improvements. It has been suggested that the increase in performance originates from changes in characteristics of the Electromyography (EMG) patterns, such as separability or repeatability. However, the relation between these EMG metrics and control performance has hardly been studied. We assessed the relation between three common EMG feature space metrics (separability, variability and repeatability) in 20 able bodied participants who learned ML myoelectric control in a virtual task over 15 training blocks on 5 days. We assessed the change in offline and real-time performance, as well as the change of each EMG metric over the training. Subsequently, we assessed the relation between individual EMG metrics and offline and real-time performance via correlation analysis. Last, we tried to predict real-time performance from all EMG metrics via L2-regularized linear regression. Results showed that real-time performance improved with training, but there was no change in offline performance or in any of the EMG metrics. Furthermore, we only found a very low correlation between separability and real-time performance and no correlation between any other EMG metric and real-time performance. Finally, real-time performance could not be successfully predicted from all EMG metrics employing L2-regularized linear regression. We concluded that the three EMG metrics and real-time performance appear to be unrelated
Serious gaming to generate separated and consistent EMG patterns in pattern-recognition prosthesis control
Pattern-Recognition (PR) control of upper-limb prosthetics has shown inconsistent results outside lab settings, which might be due to the inadequacy of usersâ electromyogram (EMG) patterns. To improve the separability and consistency of their EMG, users can receive training. Conventional training uses an internal focus of attention as prosthesis users focus on the muscle contractions of their (phantom) hand together with explicit learning processes facilitated by a coach guiding the user. In this study we investigated if an alternative training paradigm using an external focus of attention exploiting implicit learning processes based on serious gaming without a coach could lead to more separable and consistent EMG. Able-bodied participants (N = 25; mean age 22 years, 13 females) were recruited and followed conventional or game training for five days. In conventional training, participants performed the Motion Test thrice daily and received coaching on how to adapt their muscle contractions. In game training, participants controlled an avatar using a direct mapping from electrode to avatar direction. The participants utilized implicit learning processes, by exploring which muscle contractions made the avatar go in which directions. Performance in both groups was evaluated by using the Motion Test in a pre/post-test design. Training resulted in improved performance, with no differences between training paradigms. Participants who followed game training showed 51% more separated EMG patterns. EMG pattern consistency did not change over training. It was concluded that serious game training using an external focus of attention and implicit learning can be considered as a viable alternative to conventional training.</p
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