Empirical evidence for a theory of international new ventures

This paper analyzes twenty empirical studies relating to international new ventures (INVs). Based on this analysis it is shown that traditional internationalization theories do not explain INVs sufficiently. Therefore a model integrating static and process elements from the empirical evidence as well as parts of the traditional internationalization theories is developed. Obtained was an eclectic theory describing and explaining the rise of new firms already venturing abroad briefly after the time of their formation. Key results A 4-pillar-model for explaining the internationalization of INVs is developed. The model relies on basic assumptions from the network-, the stages-, the internalization- and the monopolistic advantage theory.Born global, international new ventures, internationalization theory

The two-proton shell gap in Sn isotopes

We present an analysis of two-proton shell gaps in Sn isotopes. As the theoretical tool we use self-consistent mean-field models, namely the relativistic mean-field model and the Skyrme-Hartree-Fock approach, both with two different pairing forces, a delta interaction (DI) model and a density-dependent delta interaction (DDDI). We investigate the influence of nuclear deformation as well as collective correlations and find that both effects contribute significantly. Moreover, we find a further significant dependence on the pairing force used. The inclusion of deformation plus correlation effects and the use of DDDI pairing provides agreement with the data.Comment: gzipped tar archiv containing LaTeX source, bibliography file (*.bbl), all figures as *.eps, and the style file

Isospin Asymmetry in Nuclei and Neutron Stars

The roles of isospin asymmetry in nuclei and neutron stars are investigated using a range of potential and field-theoretical models of nucleonic matter. The parameters of these models are fixed by fitting the properties of homogeneous bulk matter and closed-shell nuclei. We discuss and unravel the causes of correlations among the neutron skin thickness in heavy nuclei, the pressure of beta-equilibrated matter at a density of 0.1 fm$^{-3}$, the derivative of the nuclear symmetry energy at the same density and the radii of moderate mass neutron stars. Constraints on the symmetry properties of nuclear matter from the binding energies of nuclei are examined. The extent to which forthcoming neutron skin measurements will further delimit the symmetry properties is investigated. The impact of symmetry energy constraints for the mass and moment of inertia contained within neutron star crusts and the threshold density for the nucleon direct Urca process, all of which are potentially measurable, is explored. We also comment on the minimum neutron star radius, assuming that only nucleonic matter exists within the star.Comment: 49 pages, 17 figures, Phys. Rep. (in press); made improvements to "RAPR" and corrected transition densitie

Structure of the Vacuum in Nuclear Matter - A Nonperturbative Approach

We compute the vacuum polarisation correction to the binding energy of nuclear matter in the Walecka model using a nonperturbative approach. We first study such a contribution as arising from a ground state structure with baryon-antibaryon condensates. This yields the same results as obtained through the relativistic Hartree approximation of summing tadpole diagrams for the baryon propagator. Such a vacuum is then generalized to include quantum effects from meson fields through scalar-meson condensates. The method is applied to study properties of nuclear matter and leads to a softer equation of state giving a lower value of the incompressibility than would be reached without quantum effects. The density dependent effective sigma mass is also calculated including such vacuum polarisation effects.Comment: 26 pages including 5 eps files, uses revtex style; PACS number: 21.65.+f,21.30.+

Nuclei in a chiral SU(3) model

Nuclei can be described satisfactorily in a nonlinear chiral SU(3)-framework, even with standard potentials of the linear $\sigma$-model. The condensate value of the strange scalar meson is found to be important for the properties of nuclei even without adding hyperons. By neglecting terms which couple the strange to the nonstrange condensate one can reduce the model to a Walecka model structure embedded in SU(3). We discuss inherent problems with chiral SU(3) models regarding hyperon optical potentials.Comment: 25 pages, RevTe

Burden of disease and impact on quality of life in chronic back pain – a comparative cross-sectional study of 150 axial spondyloarthritis and 150 orthopedic back pain patients

ObjectiveChronic back pain (CBP) constitutes one of the most common complaints in primary care and a leading cause of disability worldwide. CBP may be of mechanical or inflammatory character and may lead to functional impairment and reduced quality of life. In this study, we aimed to assess and compare burden of disease, functional capacity, quality of life and depressive symptoms in axial spondyloarthritis (axSpA) patients with orthopedic chronic back pain patients (OBP). We further aimed to identify factors associated with quality of life.MethodsCross-sectional survey of a cohort of 300 CBP patients including 150 patients from a University Hospital Orthopedic Back Pain Outpatient Clinic with OBP and 150 patients with confirmed axSpA from a University Hospital Rheumatology Outpatient Clinic. Questionnaire-based assessment of pain character (Inflammatory Back Pain, MAIL-Scale), functional status (FFbH, BASFI), quality of life (WHOQOL-Bref) and depressive symptoms (Phq9) and retrospective medical chart analysis.ResultsBoth, OBP and axSpA patients reported on average intermediate pain levels of mostly mixed pain character. Both groups demonstrated a reduced health-related quality of life and the presence of depressive symptoms. However, axSpA patients reported a significantly better subjective quality of life, more satisfaction with their health status and better functional capacity compared to OBP patients (all p < 0.001). In a multivariate regression model, depressive symptoms, mechanical back pain, pain level and age were negative predictors of subjective quality of life, whereas functional capacity was a positive predictor.ConclusionChronic back pain was associated with a high morbidity and reduced quality of life regardless of pain character. We identified multiple factors associated with reduced quality of life. Awareness and addressing of these factors may help to overcome unmet needs and improve quality of life for these patients

The Complete Genome Sequence of Thermoproteus tenax: A Physiologically Versatile Member of the Crenarchaeota

Here, we report on the complete genome sequence of the hyperthermophilic Crenarchaeum Thermoproteus tenax (strain Kra 1, DSM 2078(T)) a type strain of the crenarchaeotal order Thermoproteales. Its circular 1.84-megabase genome harbors no extrachromosomal elements and 2,051 open reading frames are identified, covering 90.6% of the complete sequence, which represents a high coding density. Derived from the gene content, T. tenax is a representative member of the Crenarchaeota. The organism is strictly anaerobic and sulfur-dependent with optimal growth at 86 degrees C and pH 5.6. One particular feature is the great metabolic versatility, which is not accompanied by a distinct increase of genome size or information density as compared to other Crenarchaeota. T. tenax is able to grow chemolithoautotrophically (CO2/H-2) as well as chemoorganoheterotrophically in presence of various organic substrates. All pathways for synthesizing the 20 proteinogenic amino acids are present. In addition, two presumably complete gene sets for NADH:quinone oxidoreductase (complex I) were identified in the genome and there is evidence that either NADH or reduced ferredoxin might serve as electron donor. Beside the typical archaeal A(0)A(1)-ATP synthase, a membrane-bound pyrophosphatase is found, which might contribute to energy conservation. Surprisingly, all genes required for dissimilatory sulfate reduction are present, which is confirmed by growth experiments. Mentionable is furthermore, the presence of two proteins (ParA family ATPase, actin-like protein) that might be involved in cell division in Thermoproteales, where the ESCRT system is absent, and of genes involved in genetic competence (DprA, ComF) that is so far unique within Archaea

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements