Physician’ entrepreneurship explained: a case study of intra-organizational dynamics in Dutch hospitals and specialty clinics

Background Challenges brought about by developments such as continuing market reforms and budget reductions have strained the relation between managers and physicians in hospitals. By applying neo-institutional theory, we research how intra-organizational dynamics between physicians and managers induce physicians to become entrepreneurs by starting a specialty clinic. In addition, we determine the nature of this change by analyzing the intra-organizational dynamics in both hospitals and clinics. Methods For our research, we interviewed a total of fifteen physicians and eight managers in four hospitals and twelve physicians and seven managers in twelve specialty clinics. Results We found evidence that in becoming entrepreneurs, physicians are influenced by intra-organizational dynamics, including power dependence, interest dissatisfaction, and value commitments, between physicians and managers as well as among physicians’ groups. The precise motivation for starting a new clinic can vary depending on the medical or business logic in which the entrepreneurs are embedded, but also the presence of an entrepreneurial nature or nurture. Finally we found that the entrepreneurial process of starting a specialty clinic is a process of sedimented change or hybridized professionalism in which elements of the business logic are added to the existing logic of medical professionalism, leading to a hybrid logic. Conclusions These findings have implications for policy at both the national and hospital level. Shared ownership and aligned incentives may provide the additional cement in which the developing entrepreneurial values are ‘glued’ to the central medical logi

Constraining the epoch of reionization with the variance statistic: simulations of the LOFAR case

Several experiments are underway to detect the cosmic redshifted 21-cm signal from neutral hydrogen from the Epoch of Reionization (EoR). Due to their very low signal-to-noise ratio, these observations aim for a statistical detection of the signal by measuring its power spectrum. We investigate the extraction of the variance of the signal as a first step towards detecting and constraining the global history of the EoR. Signal variance is the integral of the signal's power spectrum, and it is expected to be measured with a high significance. We demonstrate this through results from a simulation and parameter estimation pipeline developed for the Low Frequency Array (LOFAR)-EoR experiment. We show that LOFAR should be able to detect the EoR in 600 hours of integration using the variance statistic. Additionally, the redshift ($z_r$) and duration ($\Delta z$) of reionization can be constrained assuming a parametrization. We use an EoR simulation of $z_r = 7.68$ and $\Delta z = 0.43$ to test the pipeline. We are able to detect the simulated signal with a significance of 4 standard deviations and extract the EoR parameters as $z_r = 7.72^{+0.37}_{-0.18}$ and $\Delta z = 0.53^{+0.12}_{-0.23}$ in 600 hours, assuming that systematic errors can be adequately controlled. We further show that the significance of detection and constraints on EoR parameters can be improved by measuring the cross-variance of the signal by cross-correlating consecutive redshift bins.Comment: 13 pages, 14 figures, Accepted for publication in MNRA

Persistent Biliary Hypoxia and Lack of Regeneration Are Key Mechanisms in the Pathogenesis of Post-transplant Non-anastomotic Strictures

Non-anastomotic biliary strictures (NAS) are a major cause of morbidity after orthotopic liver transplantation (OLT). Although ischemic injury of peribiliary glands (PBGs) and peribiliary vascular plexus (PVP) during OLT has been associated with the later development of NAS, the exact underlying mechanisms remain unclear. We hypothesized that bile ducts of patients with NAS suffer from ongoing biliary hypoxia and lack of regeneration from PBG stem/progenitor cells

Tertiary lymphoid structures critical for prognosis in endometrial cancer patients

B-cells play a key role in cancer suppression, particularly when aggregated in tertiary lymphoid structures (TLS). Here, we investigate the role of B-cells and TLS in endometrial cancer (EC). Single cell RNA-sequencing of B-cells shows presence of naive B-cells, cycling/germinal center B-cells and antibody-secreting cells. Differential gene expression analysis shows association of TLS with L1CAM overexpression. Immunohistochemistry and co-immunofluorescence show L1CAM expression in mature TLS, independent of L1CAM expression in the tumor. Using L1CAM as a marker, 378 of the 411 molecularly classified ECs from the PORTEC-3 biobank are evaluated, TLS are found in 19%. L1CAM expressing TLS are most common in mismatch-repair deficient (29/127, 23%) and polymerase-epsilon mutant EC (24/47, 51%). Multivariable Cox regression analysis shows strong favorable prognostic impact of TLS, independent of clinicopathological and molecular factors. Our data suggests a pivotal role of TLS in outcome of EC patients, and establishes L1CAM as a simple biomarker.Tertiary lymphoid structures (TLS) are associated with a reduced risk of cancer recurrence and improved response to immune checkpoint blockade in several tumor types. Here the authors identify L1CAM as a marker for mature TLS and show that the presence of TLS is associated with favorable prognosis in patients with endometrial cancer from the PORTEC-3 trial.Biological, physical and clinical aspects of cancer treatment with ionising radiatio

Self-Similarity in General Relativity \endtitle

The different kinds of self-similarity in general relativity are discussed, with special emphasis on similarity of the ``first'' kind, corresponding to spacetimes admitting a homothetic vector. We then survey the various classes of self-similar solutions to Einstein's field equations and the different mathematical approaches used in studying them. We focus mainly on spatially homogenous and spherically symmetric self-similar solutions, emphasizing their possible roles as asymptotic states for more general models. Perfect fluid spherically symmetric similarity solutions have recently been completely classified, and we discuss various astrophysical and cosmological applications of such solutions. Finally we consider more general types of self-similar models.Comment: TeX document, 53 page

Coherent \pi^\circ photoproduction from ^4He

Differential cross sections and beam asymmetries for coherent \pi^\circ photoproduction from ^4He in the \Delta energy-range have been measured with high statistical and systematic precisions using both decay photons for identifying the process.The experiment was performed at the MAinz MIcrotron using the TAPS photon spectrometer and the Glasgow/Mainz tagged photon facility. The differential cross sections are in excellent agreement with predictions based on the DWIA if an appropriate parametrization of the \Delta-nuclear interaction is applied. The beam asymmetries are interpreted in terms of degrees of linear polarization of collimated coherent bremsstrahlung. The expected increase of the degree of linear polarization with decreasing collimation angle is confirmed. Agreement with calculations is obtained on a few-percent level of precision in the maxima of the coherent peaks.Comment: 22 pages, 6 figure

Hypertension Is Associated with Marked Alterations in Sphingolipid Biology: A Potential Role for Ceramide

Background Hypertension is, amongst others, characterized by endothelial dysfunction and vascular remodeling. As sphingolipids have been implicated in both the regulation of vascular contractility and growth, we investigated whether sphingolipid biology is altered in hypertension and whether this is reflected in altered vascular function. Methods and Findings In isolated carotid arteries from spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats, shifting the ceramide/S1P ratio towards ceramide dominance by administration of a sphingosine kinase inhibitor (dimethylsphingosine) or exogenous application of sphingomyelinase, induced marked endothelium-dependent contractions in SHR vessels (DMS: 1.4±0.4 and SMase: 2.1±0.1 mN/mm; n = 10), that were virtually absent in WKY vessels (DMS: 0.0±0.0 and SMase: 0.6±0.1 mN/mm; n = 9, p Conclusions Hypertension is associated with marked alterations in vascular sphingolipid biology such as elevated ceramide levels and signaling, that contribute to increased vascular tone

The Role of Turtles as Coral Reef Macroherbivores

Herbivory is widely accepted as a vital function on coral reefs. To date, the majority of studies examining herbivory in coral reef environments have focused on the roles of fishes and/or urchins, with relatively few studies considering the potential role of macroherbivores in reef processes. Here, we introduce evidence that highlights the potential role of marine turtles as herbivores on coral reefs. While conducting experimental habitat manipulations to assess the roles of herbivorous reef fishes we observed green turtles (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata) showing responses that were remarkably similar to those of herbivorous fishes. Reducing the sediment load of the epilithic algal matrix on a coral reef resulted in a forty-fold increase in grazing by green turtles. Hawksbill turtles were also observed to browse transplanted thalli of the macroalga Sargassum swartzii in a coral reef environment. These responses not only show strong parallels to herbivorous reef fishes, but also highlight that marine turtles actively, and intentionally, remove algae from coral reefs. When considering the size and potential historical abundance of marine turtles we suggest that these potentially valuable herbivores may have been lost from many coral reefs before their true importance was understood