94 research outputs found
Testing the stress of higher status hypothesis. Variation of occupational stress among physicians and nurses at a German university hospital
Studies show especially for the UK and the US that physicians experience more occupational stress than nurses. It has also been shown that a higher status within the medical and nursing hierarchy is associated with less occupational stress. Our study's aim is to examine whether these results also can be found in the context of the German university hospital sector. Thus, we test the stress of higher status hypothesis in and between the occupational groups of nurses and physicians at a German university hospital. Based on two cross-section surveys in the years of 2016 and 2019 this paper compares the perceived level of occupational stress between physicians (n = 588) and nurses (n = 735). Perceived levels of occupational stress-measured via the effort-reward imbalance model and the job demand-control model-are differentiated by status positions within and between both occupational groups. Descriptive as well as inferential statistics (Mann-Whitney U test, Kruskal-Wallis H test) are used to test the stress of higher status hypothesis. Contrary to the stress of higher status hypothesis, our main result is that physicians and nurses perceive similar levels of occupational stress. Furthermore, within each hierarchy the perceived degree of work stress decreases with increasing status for both groups. Our main conclusion is that the stress of higher status hypothesis must be rejected in the German university hospital context and the competing resources of higher status hypothesis must be assumed. The findings can be explained by the unique relationship between physicians and nurses and the role of New Public Management in the German hospital sector
The Role of Cross-Domain Use Cases in IoT â A Case Analysis
The strong rise of Internet connected things contrib- utes to the big data phenomenon. Data is increasingly becoming available from various devices in large vol- ume, variety and velocity. However, many Internet of Things (IoT) applications still seem to be used to solve single problems and infrastructural elements (e.g. sen- sors or data) are not openly available for other use cases. This paper argues that a growing need for cross- domain applications is approaching within the sharing economy and other ecosystem-based business models. It investigates the current state of such cross-domain ap- plications by analyzing currently deployed IoT case studies. The analysis shows that most cases remain in the silo mentality and focus on a specific domain. Only a few cases feature some cross-domain characteristics. These are especially present in smart city cases, which engage multiple stakeholders and promote the share of resources
Fluid dynamics of bacterial turbulence
Self-sustained turbulent structures have been observed in a wide range of
living fluids, yet no quantitative theory exists to explain their properties.
We report experiments on active turbulence in highly concentrated 3D
suspensions of Bacillus subtilis and compare them with a minimal fourth-order
vector-field theory for incompressible bacterial dynamics. Velocimetry of
bacteria and surrounding fluid, determined by imaging cells and tracking
colloidal tracers, yields consistent results for velocity statistics and
correlations over two orders of magnitude in kinetic energy, revealing a
decrease of fluid memory with increasing swimming activity and linear scaling
between energy and enstrophy. The best-fit model parameters allow for
quantitative agreement with experimental data.Comment: 5 pages, 4 figure
Hydrodynamic length-scale selection in microswimmer suspensions
A universal characteristic of mesoscale turbulence in active suspensions is the emergence of a typical vortex length scale, distinctly different from the scale invariance of turbulent high-Reynolds number flows. Collective length-scale selection has been observed in bacterial fluids, endothelial tissue, and active colloids, yet the physical origins of this phenomenon remain elusive. Here, we systematically derive an effective fourth-order field theory from a generic microscopic model that allows us to predict the typical vortex size in microswimmer suspensions. Building on a self-consistent closure condition, the derivation shows that the vortex length scale is determined by the competition between local alignment forces, rotational diffusion, and intermediate-range hydrodynamic interactions. Vortex structures found in simulations of the theory agree with recent measurements in Bacillus subtilis suspensions. Moreover, our approach yields an effective viscosity enhancement (reduction), as reported experimentally for puller (pusher) microorganisms
Revisiting the anticancer properties of phosphane(9-ribosylpurine-6-thiolato)gold(I) complexes and their 9H-purine precursors
New mono- and di-nuclear thio-purine and thio-purine nucleoside gold(I) complexes were synthesized, characterized, and evaluated in vitro for biological activities in comparison to related known purine complexes. By combining known anti-tumoral thio-purines with R(3)PAu moieties as present in auranofin, complexes with enhanced effects and selectivities were obtained, which not only act as cytostatics, but also disrupt tumor-specific processes. Their IC(50) values in cytotoxicity test with tumor cell lines ranged from three-digit nanomolar to single-digit micromolar, revealing a tentative structureâactivity relationship (SAR). Both the residues R(2) of the phosphane ligand and R(1) at C2 of the pyrimidine ring had a significant impact on the cytotoxicity. In most cases, the introduction of a ribo-furanosyl group at N9 of the purine led to a distinctly more cytotoxic complex. Most complexes were more active against multi-drug-resistant tumor cells or such lacking functional p53 when compared to the respective untreated wild type cell lines. Some nucleoside complexes displayed an interesting dose-dependent dual mode of action regarding cell cycle arrest and DNA repair mechanism. Some phosphane(purine-6-thiolato)gold (I) complexes had a stronger inhibitory effect on the thioredoxin reductase (TrxR) and on the reactive oxygen species (ROS) generation in cancer cells than is typical of other gold complexes. They also led to DNA fragmentation and showed anti-angiogenic effects. Their stability under test conditions was demonstrated by (77)Se NMR monitoring of an exemplary selenopurine complex. GRAPHICAL ABSTRACT: [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00775-022-01968-x
Ising-like critical behavior of vortex lattices in an active fluid
Turbulent vortex structures emerging in bacterial active fluids can be
organized into regular vortex lattices by weak geometrical constraints such as
obstacles. Here we show, using a continuum-theoretical approach, that the
formation and destruction of these patterns exhibit features of a continuous
second-order equilibrium phase transition, including long-range correlations,
divergent susceptibility, and critical slowing down. The emerging vorticity
field can be mapped onto a two-dimensional (2D) Ising model with
antiferromagnetic nearest-neighbor interactions by coarse-graining. The
resulting effective temperature is found to be proportional to the strength of
the nonlinear advection in the continuum model
Modeling of line roughness and its impact on the diffraction intensities and the reconstructed critical dimensions in scatterometry
We investigate the impact of line edge and line width roughness (LER, LWR) on the measured diffraction intensities in angular resolved extreme ultraviolet (EUV) scatterometry for a periodic line-space structure designed for EUV lithography. LER and LWR with typical amplitudes of a few nanometers were previously neglected in the course of the profile reconstruction. The 2D rigorous numerical simulations of the diffraction process for periodic structures are carried out with the finite element method (FEM) providing a numerical solution of the two-dimensional Helmholtz equation. To model roughness, multiple calculations are performed for domains with large periods, containing many pairs of line and space with stochastically chosen line and space widths. A systematic decrease of the mean efficiencies for higher diffraction orders along with increasing variances is observed and established for different degrees of roughness. In particular, we obtain simple analytical expressions for the bias in the mean efficiencies and the additional uncertainty contribution stemming from the presence of LER and/or LWR. As a consequence this bias can easily be included into the reconstruction model to provide accurate values for the evaluated profile parameters. We resolve the sensitivity of the reconstruction from this bias by using the LER/LWR perturbed efficiency datasets for multiple reconstructions. If the scattering efficiencies are bias-corrected, significant improvements are found in the reconstructed bottom and top widths toward the nominal values
Vafa-Witten Estimates for Compact Symmetric Spaces
We give an optimal upper bound for the first eigenvalue of the untwisted
Dirac operator on a compact symmetric space G/H with rk G-rk H\le 1 with
respect to arbitrary Riemannian metrics. We also prove a rigidity statement.Comment: LaTeX, 11 pages. V2: Rigidity statement added, minor changes. To
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