The Dyer-Roeder distance-redshift relation in inhomogeneous universes

Using Monte-Carlo methods, we determine the best-fit value of the homogeneity parameter alpha in the Dyer-Roeder distance-redshift relation for a variety of redshifts, inhomogeneity models and cosmological parameter values. The relation between alpha and the fraction of compact objects, f_p, is found to be approximately linear. This relation can be parametrized with reasonable accuracy for all cases treated in this paper by alpha = a*f_p, where a = 0.6.Comment: 5 pages, 10 figures, submitted to Phys.Rev.

Search for Supersymmetric Dark Matter with Superfluid He3 (MACHe3)

MACHe3 (MAtrix of Cells of superfluid He3) is a project of a new detector for direct Dark Matter search, using superfluid He3 as a sensitive medium. This paper presents a phenomenological study done with the DarkSUSY code, in order to investigate the discovery potential of this project of detector, as well as its complementarity with existing and planned devices.Comment: 15 pages, 5 figures, submitted to Phys. Letters B, minor changes in the tex

Two photon annihilation of Kaluza-Klein dark matter

We investigate the fermionic one-loop cross section for the two photon annihilation of Kaluza-Klein (KK) dark matter particles in a model of universal extra dimensions (UED). This process gives a nearly mono-energetic gamma-ray line with energy equal to the KK dark matter particle mass. We find that the cross section is large enough that if a continuum signature is detected, the energy distribution of gamma-rays should end at the particle mass with a peak that is visible for an energy resolution of the detector at the percent level. This would give an unmistakable signature of a dark matter origin of the gamma-rays, and a unique determination of the dark matter particle mass, which in the case studied should be around 800 GeV. Unlike the situation for supersymmetric models where the two-gamma peak may or may not be visible depending on parameters, this feature seems to be quite robust in UED models, and should be similar in other models where annihilation into fermions is not helicity suppressed. The observability of the signal still depends on largely unknown astrophysical parameters related to the structure of the dark matter halo. If the dark matter near the galactic center is adiabatically contracted by the central star cluster, or if the dark matter halo has substructure surviving tidal effects, prospects for detection look promising.Comment: 17 pages, 3 figures; slightly revised versio

Managers in the context of small business growth: a qualitative study of working conditions and wellbeing

"Purpose In view of the importance of managers’ wellbeing for their leadership behaviour, employee health, and business effectiveness and survival, a better understanding of managers’ wellbeing and working conditions is important for creating healthy and sustainable businesses. Previous research has mostly provided a static picture of managers’ wellbeing and work in the context of small businesses, missing the variability and dynamism that is characteristic of this context. Therefore, the purpose of this study is to explore how managers in small companies perceive their working conditions and wellbeing in the context of business growth. Methods The study is based on qualitative semi-structured interviews with 20 managers from twelve small companies. Content and thematic analysis were applied. Results The findings indicate that a manager’s working environment evolves from its initial stages and through the company’s growth, leading to variations over time in the manager’s experiences of wellbeing and work–life balance as well as changes in job demands and resources. Managers’ working situation becomes less demanding and more manageable when workloads and working hours are reduced and a better work–life balance is achieved. The perceived improvement is related to changes in organizational factors (e.g. company resources), but also to individual factors (e.g. managers’ increased awareness of the importance of a sustainable work situation). However, there were differences in how the working conditions and wellbeing changed over time and how organizational and individual resources affected the studied managers’ wellbeing. Conclusions This study shows that, in the context of small business, managers’ working conditions and wellbeing are dynamic and are linked to growth-related changes that occur from the start of organizational activities and during periods of growth. In addition, the findings suggest that changes in managers’ working conditions and wellbeing follow different trajectories over time because of the interaction between organizational and personal factors."This research received no external funding. Open access funding provided by University of Gävle

Managers' and employees' experiences of how managers' wellbeing impacts their leadership behaviours in Swedish small businesses

BACKGROUND: There is a growing interest in managers' wellbeing due to the observed associations between their wellbeing and leadership behaviours, and between leadership behaviours and employees' wellbeing. However, it is still unclear how managers' wellbeing influences their practiced leadership across different workplace contexts, which specific behaviours are affected, and how this varies across time. OBJECTIVE: The purpose of this study was therefore to explore managers' and employees' experiences and perceptions regarding the consequences of managers' wellbeing for their leadership behaviours in small businesses. METHODS: Semi-structured interviews were conducted with 39 participants (20 managers and 19 employees) working at 12 Swedish small firms, and analysed using content analysis. RESULTS: The findings showthat managers were more constructive when they felt well, and more passively destructive when unwell. Variations in managers' wellbeing influenced their mood, energy level, and performance, as well as the company's working climate. However, these destructive leadership variations did not have a substantial impact, because several protective factors were present. CONCLUSION: This study shows that the wellbeing of managers in small businesses has perceptible consequences for their leadership behaviours. The study also shows that sustained leadership behaviours may coexist with temporary variations of these behaviours on a constructive-destructive continuum depending on the leader's wellbeing. Overall, the findings contribute to a more nuanced and dynamic understanding of how the interaction between managers' wellbeing and their behaviours unfolds in the particular context of small companies

The Photovoltaic Crisis and the Demand-side Generation in Spain

The RES-E promotion policy in Spain gave priority to the photovoltaic (henceforth, PV) ground-mounted installations. For years, the coupling of customer-side generation coupled with excess energy exports was never specifically considered. However, some months ago this option was suggested as a way to recover the Spain��s PV sector from the current moratorium on the RES-E policy. A decree draft on on-site generation was issued, its central point being the consideration of electricity exports as delayed consumption rights. But several barriers hinder its entry into force. Unfortunately, Spain could be losing an important opportunity for encouraging PV investments while retail grid parity is being reached. This working paper analyzes the different types of PV demand-side generation from the point of view of consumer-generators and evaluates the economic and technical features of the regulation proposed in Spain and to date still pending

Constraining dark energy

In this paper we propose a mechanism that protects theories violating a holographic bound suggested in arXiv:1203.5476 from developing accelerated expansion. The mechanism builts on work on transplanckian physics, and a non-trivial choice of vacuum states. If correct, it lends further support for detectable signatures in the CMBR signalling new physics.Comment: 8 pages. arXiv admin note: text overlap with arXiv:astro-ph/0606474. Minor misprints correcte