Model uncertainty is one of the most pervasive challenges in the social sciences. Cross-country studies in entrepreneurship have largely ignored this issue. In this paper, we evaluate the robustness ...of 44 possible determinants of early-stage opportunity-motivated entrepreneurship (OME) and necessity-motivated entrepreneurship (NME) that are broadly classified in four groups: (1) economic variables, (2) formal institutions, (3) cultural values, and (4) legal origins and geography. The results, which are based on a representative world sample of up to 73 countries, suggest that institutional variables associated with the principles of economic freedom are most robustly correlated with OME and NME. Our findings also identify net income inequality and Scandinavian legal origins as weakly robust predictors of both types of entrepreneurial activity. Furthermore, we find that log GDP per capita is only a weakly robust predictor of NME, but not OME. We discuss implications for future research.
Precision experiments, such as the search for a deuteron electric dipole moment using storage rings like COSY, demand for an understanding of the spin dynamics with unprecedented accuracy. In such an ...enterprise, numerical predictions play a crucial role for the development and later application of spin-tracking algorithms. Various measurement concepts involving polarization effects induced by an rf Wien filter and static solenoids in COSY are discussed. The matrix formalism, applied here, deals solely with spin rotations on the closed orbit of the machine, and is intended to provide numerical guidance for the development of beam and spin-tracking codes for rings that employ realistic descriptions of the electric and magnetic bending and focusing elements, solenoids, etc., and a realistically modeled rf Wien filter.
Education is considered one of the most critical human capital investments. But does formal educational attainment "pay off" in terms of job satisfaction? To answer this question, in Study 1 we use a ...meta-analytic technique to examine the correlation between educational attainment and job satisfaction (k = 74, N = 134,924) and find an effect size close to zero. We then build on the job demands-resources (JD-R) model and research that distinguishes between working conditions and perceived stress to theorize that educational attainment involves notable trade-offs. In Study 2 we develop and test a multipath, two-stage mediation model using a nationally representative sample to explore this idea. We find that, while better-educated individuals enjoy greater job resources (income, job autonomy, and job variety), they also tend to incur greater job demands (work hours, task pressure, job intensity, and time urgency). On average, these demands are associated with increased job stress and decreased job satisfaction, largely offsetting the positive gains associated with greater resources. Given that the net relationship between education and job satisfaction emerges as weakly negative, we highlight that important trade-offs underlie the education-job satisfaction link. In supplemental analyses, we identify boundary conditions based on gender and self-employment status (such that being female exacerbates, and being self-employed attenuates, the negative association between education and job satisfaction). Finally, we discuss the practical implications for individuals and organizations, as well as alternative explanations for the education-job satisfaction link.
Tactile information is detected by thermoreceptors and mechanoreceptors in the skin and integrated by the central nervous system to produce the perception of somatosensation. Here we investigate the ...mechanism by which thermal and mechanical stimuli begin to interact and report that it is achieved by the mechanotransduction apparatus in cutaneous mechanoreceptors. We show that moderate cold potentiates the conversion of mechanical force into excitatory current in all types of mechanoreceptors from mice and tactile-specialist birds. This effect is observed at the level of mechanosensitive Piezo2 channels and can be replicated in heterologous systems using Piezo2 orthologs from different species. The cold sensitivity of Piezo2 is dependent on its blade domains, which render the channel resistant to cold-induced perturbations of the physical properties of the plasma membrane and give rise to a different mechanism of mechanical activation than that of Piezo1. Our data reveal that Piezo2 is an evolutionarily conserved mediator of thermal–tactile integration in cutaneous mechanoreceptors.
Spurious signals induced by curved spacetime in the gravity field of the rotating Earth in experiments on the search for the electric dipole moment of charged particles manifested by the spin ...rotation in pure electrostatic storage rings have been analyzed with the focus on effects of Earth’s rotation. It has been found that the rotation of the plane of an electrostatic storage ring together with the Earth generates a nonzero magnetic field. Locally in the storage ring, the spin precession frequency linear in Earth’s rotation is much higher than the frequency of the spin precession caused by the electric dipole moments. It has been argued that the integral spurious spin rotation for a particle on an ideal orbit is strongly suppressed because the contribution from Earth’s rotation is sign-alternating along the storage ring. A background signal quadratic in Earth’s rotation is finite but small.
An algorithm and a system for the operational correction of the harvesting and transport complex composition for harvesting grain crops are developed. The system allows to adjust the structure of ...machine groups for harvesting, transhipment and transportation of grain promptly. The system is based on the machine conditions' real-time monitoring and the transfer of control actions through a single control centre. The use of such organization of work reduces unproductive downtime of machines. As a result, the cost is reduced and the productivity of harvesting and transport groups is growing.
Transient receptor potential (TRP) channels are polymodal molecular sensors involved in numerous physiological processes and implicated in a variety of human diseases. Several structures of the ...founding member of the TRP channel family, TRPV1, are available, all of which were determined for the protein missing the N- and C-termini and the extracellular S5-P-loop. Here, we present structures of the full-length thirteen-lined ground squirrel TRPV1 solved by cryo-EM. Our structures resolve the extracellular cap domain formed by the S5-P-loops and the C-terminus that wraps around the three-stranded β-sheet connecting elements of the TRPV1 intracellular skirt. The cap domain forms a dome above the pore's extracellular entrance, with four portals leading to the ion conductance pathway. Deletion of the cap increases the TRPV1 average conductance, reduces the open probability and affects ion selectivity. Our data show that both the termini and the cap domain are critical determinants of TRPV1 function.
This work is aimed to study experimental and theoretical approaches for searching effective local training rules for unsupervised pattern recognition by high-performance memristor-based Spiking ...Neural Networks (SNNs). First, the possibility of weight change using Spike-Timing-Dependent Plasticity (STDP) is demonstrated with a pair of hardware analog neurons connected through a (CoFeB)x(LiNbO3)1−x nanocomposite memristor. Next, the learning convergence to a solution of binary clusterization task is analyzed in a wide range of memristive STDP parameters for a single-layer fully connected feedforward SNN. The memristive STDP behavior supplying convergence in this simple task is shown also to provide it in the handwritten digit recognition domain by the more complex SNN architecture with a Winner-Take-All competition between neurons. To investigate basic conditions necessary for training convergence, an original probabilistic generative model of a rate-based single-layer network with independent or competing neurons is built and thoroughly analyzed. The main result is a statement of “correlation growth-anticorrelation decay” principle which prompts near-optimal policy to configure model parameters. This principle is in line with requiring the binary clusterization convergence which can be defined as the necessary condition for optimal learning and used as the simple benchmark for tuning parameters of various neural network realizations with population-rate information coding. At last, a heuristic algorithm is described to experimentally find out the convergence conditions in a memristive SNN, including robustness to a device variability. Due to the generality of the proposed approach, it can be applied to a wide range of memristors and neurons of software- or hardware-based rate-coding single-layer SNNs when searching for local rules that ensure their unsupervised learning convergence in a pattern recognition task domain.
•Supporting correlations in activities of neurons is a near-optimal learning policy.•Binary clusterization can be a benchmark for tuning parameters of a rate-coding SNN.•Shaping memristive STDP window for binary clusterization helps in more complex tasks.•Nanocomposite LiNbO3-based memristors are suitable for always-on learning SNNs.
•Interaction of low intensity ultrasound with liquid jet creates vortices.•The vortices serve as a template for the formation of hydroxyapatite crystals.•Ultrasound in non-cavitation mode makes ...smaller particles than in cavitation mode.
The size control of materials is of great importance in research and technology because materials of different size and shape have different properties and applications.
This paper focuses on the synthesis of hydroxyapatite in ultrasound fields of different frequencies and intensities with the aim to find the conditions which allow control of the particles size. The results are evaluated by X-ray diffraction, Transmission Electron Microscopy, morphological and sedimentation analyses. It is shown that the hydroxyapatite particles synthesized at low intensity non-cavitation regime of ultrasound have smaller size than those prepared at high intensity cavitation regime. The explanation of observed results is based on the idea of formation of vortices at the interface between phosphoric acid and calcium hydroxide solution where the nucleation of hydroxyapatite particles is taken place. Smaller vortices formed at high frequency non-cavitation ultrasound regime provide smaller nucleation sites and smaller resulting particles, compared to vortices and particles obtained without ultrasound. Discovered method has a potential of industrial application of ultrasound for the controlled synthesis of nanoparticles.
Pain therapy has remained conceptually stagnant since the opioid crisis, which highlighted the dangers of treating pain with opioids. An alternative addiction-free strategy to conventional ...painkiller-based treatment is targeting receptors at the origin of the pain pathway, such as transient receptor potential (TRP) ion channels. Thus, a founding member of the vanilloid subfamily of TRP channels, TRPV1, represents one of the most sought-after pain therapy targets. The need for selective TRPV1 inhibitors extends beyond pain treatment, to other diseases associated with this channel, including psychiatric disorders. Here we report the cryo-electron microscopy structures of human TRPV1 in the apo state and in complex with the TRPV1-specific nanomolar-affinity analgesic antagonist SB-366791. SB-366791 binds to the vanilloid site and acts as an allosteric hTRPV1 inhibitor. SB-366791 binding site is supported by mutagenesis combined with electrophysiological recordings and can be further explored to design new drugs targeting TRPV1 in disease conditions.
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