Spacelike hypersurfaces in standard static spacetimes

In this work we study spacelike hypersurfaces immersed in spatially open standard static spacetimes with complete spacelike slices. Under appropriate lower bounds on the Ricci curvature of the spacetime in directions tangent to the slices, we prove that every complete CMC hypersurface having either bounded hyperbolic angle or bounded height is maximal. Our conclusions follow from general mean curvature estimates for spacelike hypersurfaces. In case where the spacetime is a Lorentzian product with spatial factor of nonnegative Ricci curvature and sectional curvatures bounded below, we also show that a complete maximal hypersurface not intersecting a spacelike slice is itself a slice. This result is obtained from a gradient estimate for parametric maximal hypersurfaces.Comment: 50 page

Rigidity results for complete spacelike submanifolds in plane fronted waves

New rigidity results for complete non-compact spacelike submanifolds of arbitrary codimension in plane fronted waves are obtained. Under appropriate assumptions, we prove that a complete spacelike submanifold in these spacetimes is contained in a characteristic lightlike hypersurface. Moreover, for a complete codimension two extremal submanifold in a plane fronted wave we show sufficient conditions to guarantee that it is a (totally geodesic) wavefront.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. Funding for open access charge: Universidad de Málaga / CBU

Completeness of uniformly accelerated observers in Galilean spacetimes

We analyze the concept of uniformly accelerated observer in Galilean spacetimes in the context of Newton–Cartan theory and find natural geometric assumptions to ensure that an inextensible uniformly accelerated observer in a Galilean spacetime does not disappear in a finite proper time

Leaf morphological and physiological adaptations of a deciduous oak (Quercus faginea Lam.) to the Mediterranean climate: A comparison with a closely related temperate species (Quercus robur L.)

'White oaks' - one of the main groups of the genus Quercus L. - are represented in western Eurasia by the 'roburoid oaks', a deciduous and closely related genetic group that should have an Arcto-Tertiary origin under temperate-nemoral climates. Nowadays, roburoid oak species such as Quercus robur L. are still present in these temperate climates in Europe, but others are also present in southern Europe under Mediterranean-type climates, such as Quercus faginea Lam. We hypothesize the existence of a coordinated functional response at the whole-shoot scale in Q. faginea under Mediterranean conditions to adapt to more xeric habitats. The results reveal a clear morphological and physiological segregation between Q. robur and Q. faginea, which constitute two very contrasting functional types in response to climate dryness. The most outstanding divergence between the two species is the reduction in transpiring area in Q. faginea, which is the main trait imposed by the water deficit in Mediterranean-type climates. The reduction in leaf area ratio in Q. faginea should have a negative effect on carbon gain that is partially counteracted by a higher inherent photosynthetic ability of Q. faginea when compared with Q. robur, as a consequence of higher mesophyll conductance, higher maximum velocity of carboxylation and much higher stomatal conductance (gs). The extremely high gs of Q. faginea counteracts the expected reduction in gs imposed by the stomatal sensitivity to vapor pressure deficit, allowing this species to diminish water losses maintaining high net CO2 assimilation values along the vegetative period under nonlimiting soil water potential values. In conclusion, the present study demonstrates that Q. faginea can be regarded as an example of adaptation of a deciduous oak to Mediterranean-type climates. © 2015 The Author 2015.Publishe

Cell-level anatomical characteristics explain high mesophyll conductance and photosynthetic capacity in sclerophyllous Mediterranean oaks

Leaf mass per area (LMA) has been suggested to negatively affect the mesophyll conductance to CO2 (g(m)), which is the most limiting factor for area-based photosynthesis (A(N)) in many Mediterranean sclerophyll species. However, despite their high LMA, these species have similar A(N) to plants from other biomes. Variations in other leaf anatomical traits, such as mesophyll and chloroplast surface area exposed to intercellular air space (S-m/S and S-c/S), may offset the restrictions imposed by high LMA in g(m) and A(N) in these species. Seven sclerophyllous Mediterranean oaks from Europe/North Africa and North America with contrasting LMA were compared in terms of morphological, anatomical and photosynthetic traits. Mediterranean oaks showed specific differences in A(N) that go beyond the common morphological leaf traits reported for these species (reduced leaf area and thick leaves). These variations resulted mainly from the differences in g(m), the most limiting factor for carbon assimilation in these species. Species with higher A(N) showed increased S-c/S, which implies increased g(m) without changes in stomatal conductance. The occurrence of this anatomical adaptation at the cell level allowed evergreen oaks to reach A(N) values comparable to congeneric deciduous species despite their higher LMA.Se agradece el apoyo financiero del Gobierno de Aragón (grupo de investigación H38). El trabajo de Domingo Sancho Knapik está financiado por un contrato DOC INIA cofinanciado por el Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA) de España y el Fondo Social Europeo (FSE).anatomical adaptationsleafmass per area (LMA)Mediterranean-typeclimatemesophyll conductance (gm)photosynthesisQuercussclerophyllyPublishe

Development of an activity disease score in patients with uveitis (UVEDAI)

To develop a disease activity index for patients with uveitis (UVEDAI) encompassing the relevant domains of disease activity considered important among experts in this field. The steps for designing UVEDAI were: (a) Defining the construct and establishing the domains through a formal judgment of experts, (b) A two-round Delphi study with a panel of 15 experts to determine the relevant items, (c) Selection of items: A logistic regression model was developed that set ocular inflammatory activity as the dependent variable. The construct "uveitis inflammatory activity" was defined as any intraocular inflammation that included external structures (cornea) in addition to uvea. Seven domains and 15 items were identified: best-corrected visual acuity, inflammation of the anterior chamber (anterior chamber cells, hypopyon, the presence of fibrin, active posterior keratic precipitates and iris nodules), intraocular pressure, inflammation of the vitreous cavity (vitreous haze, snowballs and snowbanks), central macular edema, inflammation of the posterior pole (the presence and number of choroidal/retinal lesions, vascular inflammation and papillitis), and global assessment from both (patient and physician). From all the variables studied in the multivariate model, anterior chamber cell grade, vitreous haze, central macular edema, inflammatory vessel sheathing, papillitis, choroidal/retinal lesions and patient evaluation were included in UVEDAI. UVEDAI is an index designed to assess the global ocular inflammatory activity in patients with uveitis. It might prove worthwhile to motorize the activity of this extraarticular manifestation of some rheumatic diseases

Positively selected amino acid replacements within the RuBisCO enzyme of oak trees are associated with ecological adaptations

Phylogenetic analysis by maximum likelihood (PAML) has become the standard approach to study positive selection at the molecular level, but other methods may provide complementary ways to identify amino acid replacements associated with particular conditions. Here, we compare results of the decision tree (DT) model method with ones of PAML using the key photosynthetic enzyme RuBisCO as a model system to study molecular adaptation to particular ecological conditions in oaks (Quercus). We sequenced the chloroplast rbcL gene encoding RuBisCO large subunit in 158 Quercus species, covering about a third of the global genus diversity. It has been hypothesized that RuBisCO has evolved differentially depending on the environmental conditions and leaf traits governing internal gas diffusion patterns. Here, we show, using PAML, that amino acid replacements at the residue positions 95, 145, 251, 262 and 328 of the RuBisCO large subunit have been the subject of positive selection along particular Quercus lineages associated with the leaf traits and climate characteristics. In parallel, the DT model identified amino acid replacements at sites 95, 219, 262 and 328 being associated with the leaf traits and climate characteristics, exhibiting partial overlap with the results obtained using PAML