17 research outputs found

    Regular black holes in quadratic gravity

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    The first-order correction of the perturbative solution of the coupled equations of the quadratic gravity and nonlinear electrodynamics is constructed, with the zeroth-order solution coinciding with the ones given by Ay\'on-Beato and Garc{\'\i}a and by Bronnikov. It is shown that a simple generalization of the Bronnikov's electromagnetic Lagrangian leads to the solution expressible in terms of the polylogarithm functions. The solution is parametrized by two integration constants and depends on two free parameters. By the boundary conditions the integration constants are related to the charge and total mass of the system as seen by a distant observer, whereas the free parameters are adjusted to make the resultant line element regular at the center. It is argued that various curvature invariants are also regular there that strongly suggests the regularity of the spacetime. Despite the complexity of the problem the obtained solution can be studied analytically. The location of the event horizon of the black hole, its asymptotics and temperature are calculated. Special emphasis is put on the extremal configuration

    Thermodynamic Properties of Methanol in the Critical and Supercritical Regions

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    The healthcare system and provision of oral healthcare in European Union member states. Part 4: Greece

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    This paper presents a description of the healthcare system and how oral healthcare is organised and provided in Greece, a country in a deep economic and social crisis. The national health system is underfunded, with severe gaps in staffing levels and the country has a large private healthcare sector. Oral healthcare has been largely provided in the private sector. Most people are struggling to survive and have no money to spend on general and oral healthcare. Unemployment is rising and access to healthcare services is more difficult than ever. Additionally, there has been an overproduction of dentists and no development of team dentistry. This has led to under or unemployment of dentists in Greece and their migration to other European Union member states, such as the United Kingdom, where over 600 Greek dentists are currently working. © 2015 British Dental Association

    New findings on the true-branched monotypic genus Iphinoe (Cyanobacteria) from geographically isolated caves (Greece)

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    The type of branching is a morphological character of great significance, separating taxa within the true-branched cyanobacteria. In this paper, true-branched morphospecies of cyanobacteria belonging to genus Iphinoe Lamprinou et Pantazidou, from different and geographically isolated caves of Greece, were investigated by coupling classical approach i.e. microscopy analysis (LM, SEM, TEM, CLSM) and molecular analysis (16S rRNA gene diversity). The morphological study revealed interspecific differences which could be attributed to adaptations to local conditions: Iphinoe cf. spelaeobios from the cave 'Diktaion Andron' (Crete island) exhibit different type of branching (Y- and T-type) and smaller size compared to the type species Iphinoe spelaeobios (T- and V-type of branching) from the caves 'Kastria' and 'Koutouki' (Peloponnese, Attica). Despite their phenotypic differences and geographical isolation molecular analysis showed identical 16S rRNA sequences which indicate that both populations belong to the same genus. © Czech Phycological Society (2013)

    The combination of calcium ionophore A23187 and GM-CSF can safely salvage aged human unfertilized oocytes after ICSI

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    Purpose: Artificial oocyte activation using calcium ionophores and enhancement of embryonic developmental potential by the granulocyte-macrophage colony-stimulating factor (GM-CSF) have already been reported. In this study, we evaluated the synergistic effect of these two methods on aged human unfertilized oocytes after intracytoplasmic sperm injection (ICSI). Then, we cultured the resulting embryos to the blastocyst stage and screened them for chromosomal abnormalities, to assess the safety of this protocol. Methods: Aged human oocytes deemed unfertilized after ICSI were activated, either by briefly applying the calcium ionophore A23187 alone (group A) or by briefly applying the ionophore and then supplementing the culture medium with recombinant human GM-CSF (rhGM-CSF) (group B). Next, the development was monitored in a time-lapse incubator system, and ploidy was analyzed by array comparative genomic hybridization (aCGH), after whole embryo biopsy and whole genome amplification. Differences between oocytes and resulting embryos in both groups were evaluated statistically. Results: Oocytes unfertilized after ICSI can be activated with the calcium ionophore A23187 to show two pronuclei and two polar bodies. Addition of rhGM-CSF in the culture medium of A23187-activated oocytes enhances their cleaving and blastulation potential and results in more euploid blastocysts compared to the culture medium alone. Conclusions: This study shows that activating post-ICSI aged human unfertilized oocytes with a combination of a calcium ionophore and a cytokine can produce good-morphology euploid blastocysts. © 2016, Springer Science+Business Media New York

    Implementation of the Water Framework Directive: Lessons Learned and Future Perspectives for an Ecologically Meaningful Classification Based on Phytoplankton of the Status of Greek Lakes, Mediterranean Region

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    The enactment of the Water Framework Directive (WFD) initiated scientific efforts to develop reliable methods for comparing prevailing lake conditions against reference (or nonimpaired) states, using the state of a set biological elements. Drawing a distinction between impaired and natural conditions can be a challenging exercise. Another important aspect is to ensure that water quality assessment is comparable among the different Member States. In this context, the present paper offers a constructive critique of the practices followed during the WFD implementation in Greece by pinpointing methodological weaknesses and knowledge gaps that undermine our ability to classify the ecological quality of Greek lakes. One of the pillars of WDF is a valid lake typology that sets ecological standards transcending geographic regions and national boundaries. The national typology of Greek lakes has failed to take into account essential components. WFD compliance assessments based on the descriptions of phytoplankton communities are oversimplified and as such should be revisited. Exclusion of most chroococcal species from the analysis of cyanobacteria biovolume in Greek lakes/reservoirs and most reservoirs in Spain, Portugal, and Cyprus is not consistent with the distribution of those taxa in lakes. Similarly, the total biovolume reference values and the indices used in classification schemes reflect misunderstandings of WFD core principles. This hampers the comparability of ecological status across Europe and leads to quality standards that are too relaxed to provide an efficient target for the protection of Greek/transboundary lakes such as the ancient Lake Megali Prespa. © 2019, Springer Science+Business Media, LLC, part of Springer Nature

    No evidence that embryo selection by near-infrared spectroscopy in addition to morphology is able to improve live birth rates: results from an individual patient data meta-analysis

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    STUDY QUESTIONWhat is the value of embryo selection by metabolomic profiling of culture medium with near-infrared (NIR) spectroscopy as an adjunct to morphology, compared with embryo selection by morphology alone, based on an individual patient data meta-analysis (IPD MA)?SUMMARY ANSWERThe IPD MA indicates that the live birth rate after embryo selection by NIR spectroscopy and morphology is not significantly different compared with the live birth rate after embryo selection by morphology alone.WHAT IS KNOWN ALREADYRetrospective proof of principle studies has consistently shown that high NIR viability scores are correlated with a high implantation potential of embryos. However, randomized controlled trials (RCTs) have generally shown no benefit of the NIR technology over embryo morphology, although there have been some conflicting results between pregnancy outcomes on different days of embryo transfer.STUDY DESIGN, SIZE, DURATIONThis IPD MA included all existing RCTs (n = 4) in which embryo selection by morphology was compared with embryo selection by morphology and the use of NIR spectroscopy of spent embryo culture medium by the Viametrics-
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