Growth variability of Scots pine (Pinus sylvestris) along a West-East gradient across northern Fennoscandia: a dendroclimatic approach

We performed a spatiotemporal analysis of a network of 21 Scots pine (Pinus sylvestris) ring-width chronologies in northern Fennoscandia by means of chronology statistics and multivariate analyses. Chronologies are located on both sides (western and eastern) of the Scandes Mountains (67°N-70°N, 15°E-29°E). Growth relationships with temperature, precipitation, and North Atlantic Oscillation (NAO) indices were calculated for the period 1880-1991. We also assessed their temporal stability. Current July temperature and, to a lesser degree, May precipitation are the main growth limiting factors in the whole area of study. However, Principal Component Analysis (PCA) and mean interseries correlation revealed differences in radial growth between both sides of the Scandes Mountains, attributed to the Oceanic-Continental climatic gradient in the area. The gradient signal is temporally variable and has strengthened during the second half of the 20th century. Northern Fennoscandia Scots pine growth is positively related to early winter NAO indices previous to the growth season and to late spring NAO. NAO/growth relationships are unstable and have dropped in the second half of the 20th century. Moreover, they are noncontinuous through the range of NAO values: for early winter, only positive NAO indices enhance tree growth in the next growing season, while negative NAO does not. For spring, only negative NAO is correlated with radial growth.

On the existence and function of galanin receptor heteromers in the central nervous system

Galanin receptor (GalR) subtypes 1-3 linked to central galanin neurons may form heteromers with each other and other types of G protein-coupled receptors in the central nervous system (CNS). These heteromers may be one molecular mechanism for galanin peptides and their N-terminal fragments (gal 1-15) to modulate the function of different types of glia-neuronal networks in the CNS, especially the emotional and the cardiovascular networks. GalR-5-HT1A heteromers likely exist with antagonistic GalR-5-HT1A receptor-receptor interactions in the ascending midbrain raphe 5-HT neuron systems and their target regions. They represent a novel target for antidepressant drugs. Evidence is given for the existence of GalR1-5-HT1A heteromers in cellular models with trans-inhibition of the protomer signaling. A GalR1-GalR2 heteromer is proposed to be a galanin N-terminal fragment preferring receptor (1-15) in the CNS. Furthermore, a GalR1-GalR2-5-HT1A heterotrimer is postulated to explain why only galanin (1-15) but not galanin (1-29) can antagonistically modulate the 5-HT1A receptors in the dorsal hippocampus rich in gal fragment binding sites. The results underline a putative role of different types of GalR-5-HT1A heteroreceptor complexes in depression. GalR antagonists may also have therapeutic actions in depression by blocking the antagonistic GalR-NPYY1 receptor interactions in putative GalR-NPYY1 receptor heteromers in the CNS resulting in increases in NPYY1 transmission and antidepressant effects. In contrast the galanin fragment receptor (a postulated GalR1-GalR2 heteromer) appears to be linked to the NPYY2 receptor enhancing the affinity of the NPYY2 binding sites in a putative GalR1-GalR2-NPYY2 heterotrimer. Finally, putative GalR-α2-adrenoreceptor heteromers with antagonistic receptor-receptor interactions may be a widespread mechanism in the CNS for integration of galanin and noradrenaline signals also of likely relevance for depression

Differential growth responses to water balance of coexisting deciduous tree species are linked to wood density in a Bolivian tropical dry forest

A seasonal period of water deficit characterizes tropical dry forests (TDFs). There, sympatric tree species exhibit a diversity of growth rates, functional traits, and responses to drought, suggesting that each species may possess different strategies to grow under different conditions of water availability. The evaluation of the long-term growth responses to changes in the soil water balance should provide an understanding of how and when coexisting tree species respond to water deficit in TDFs. Furthermore, such differential growth responses may be linked to functional traits related to water storage and conductance. We used dendrochronology and climate data to retrospectively assess how the radial growth of seven coexisting deciduous tree species responded to the seasonal soil water balance in a Bolivian TDF. Linear mixed-effects models were used to quantify the relationships between basal area increment and seasonal water balance. We related these relationships with wood density and sapwood production to assess if they affect the growth responses to climate. The growth of all species responded positively to water balance during the wet season, but such responses differed among species as a function of their wood density. For instance, species with a strong growth response to water availability averaged a low wood density which may facilitate the storage of water in the stem. By contrast, species with very dense wood were those whose growth was less sensitive to water availability. Coexisting tree species thus show differential growth responses to changes in soil water balance during the wet season. Our findings also provide a link between wood density, a trait related to the ability of trees to store water in the stem, and wood formation in response to water availability.

Reaction time asymmetries between expansion and contraction

Different asymmetries between expansion and contraction (radial motions) have been reported in the literature. Often these patterns have been regarded as implying different channels for each type of radial direction (outward versus inwards) operating at a higher level of visual motion processing. In two experiments (detection and discrimination tasks) we report reaction time asymmetries between expansion and contraction. Power functions were fitted to the data. While an exponent of 0.5 accounted for the expansion data better, a value of unity yielded the best fit for the contraction data. Instead of interpreting these differences as corresponding to different higher order motion detectors, we regard these findings as reflecting the fact that expansion and contraction tap two distinct psychophysical input channels underlying the processing of fast and slow velocities respectively.

LS 5039: A runaway microquasar ejected from the galactic plane

We have compiled optical and radio astrometric data of the microquasar LS 5039 and derived its proper motion. This, together with the distance and radial velocity of the system, allows us to state that this source is escaping from its own regional standard of rest, with a total systemic velocity of about 150 km/s and a component perpendicular to the galactic plane larger than 100 km/s. This is probably the result of an acceleration obtained during the supernova event that created the compact object in this binary system. We have computed the trajectory of LS 5039 in the past, and searched for OB associations and supernova remnants in its path. In particular, we have studied the possible association between LS 5039 and the supernova remnant G016.8-01.1, which, despite our efforts, remains dubious. We have also discovered and studied an HI cavity in the ISM, which could have been created by the stellar wind of LS 5039 or by the progenitor of the compact object in the system. Finally, in the symmetric supernova explosion scenario, we estimate that at least 17 solar masses were lost in order to produce the high eccentricity observed. Such a mass loss could also explain the observed runaway velocity of the microquasar.

Transverse and longitudinal components of the propagating and evanescent waves associated to radially-polarized nonparaxial fields

A comparison is established between the contributions of transverse and longitudinal components of both the propagating and the evanescent waves associated to freely propagating radially polarized nonparaxial beams. Attention is focused on those fields that remain radially polarized upon propagation. In terms of the plane-wave angular spectrum of these fields, analytical expressions are given for determining both the spatial shape of the above components and their relative weight integrated over the whole transverse plane. The results are applied to two kinds of doughnut-like beams with radial polarization, and we compare the behavior of such fields at two transverse planes.

Drug abuse, brain calcification and glutamate-induced neurodegeneration

Positive and negative reinforcing systems are part of the mechanism of drug dependence. Drugs with abuse potential may change the manner of response to negative emotional stimuli, activate positive emotional reactions and possess primary reinforcing properties. Catecholaminergic and peptidergic processes are of importance in these mechanisms. Current research needs to understand the types of adaptations that underlie the particularly long-lived aspects of addiction. Presently, glutamate is candidate to play a role in the enduring effects of drugs of abuse. For example, it participates in the chronic pathological changes of corticostriatal terminals produced by methamphetamine. At the synaptic level, a link between over-activation of glutamate receptors, [C(a2+)](i) increase and neuronal damage has been clearly established leading to neurodegeneration. Thus, neurodegeneration can start after an acute over-stimulation whose immediate effects depend on a diversity of calcium-activated mechanisms. If sufficient, the initial insult results in calcification and activation of a chronic on-going process with a progressive loss of neurons. At present, long-term effects of drug dependence underlie an excitotoxicity process linked to a polysynaptic pathway that dynamically regulates synaptic glutamate. Retaliatory mechanisms include energy capability of the neurons, inhibitory systems and cytoplasmic calcium precipitation as part of the neuron-glia interactions. This paper presents an integrated view of these molecular and cellular mechanisms to help understand their relationship and interdependence in a chronic pathological process that suggest new targets for therapeutic intervention.

Estudio del desarrollo y conectividad de las neuronas vasotocinérgicas en el prosencéfalo de pollo

En este Trabajo de Fin de Grado se estudia el origen embrionario de las distintas poblaciones neuronales que forman la amígdala medial extendida. La amígdala es una estructura del cerebro anterior involucrada en otorgar un significado emocional a los estímulos ambientales y en el control de distintos aspectos del comportamiento social (p.ej. comportamientos sexual, maternal, agresivo y afiliativo). Ante dichos estímulos, la amígdala pone en marcha una serie de reacciones de carácter motor, autonómico y endocrino que constituyen la respuesta emocional. Algunos desórdenes de carácter neuropsiquiátrico en humanos están relacionados con una disfunción en el control de las emociones y del comportamiento social, y varios de ellos se asocian a alteraciones en el desarrollo de la amígdala. El objetivo del presente trabajo ha sido investigar el origen de las neuronas de la amígdala medial extendida en embriones de pollo (E15 y E18) mediante ensayos de inmunocitoquímica, técnica utilizada para localizar las células que contienen el neuropéptido vasotocina (AVT) y proteínas reguladoras del desarrollo (la producida a partir del gen Otp) para ayudar en la delimitación de los distintos dominios embrionarios del prosencéfalo y distintas subdivisiones de la amígdala extendida. Los resultados de estos ensayos se combinaron con ensayos de trazado de conexiones para analizar la conectividad de las neuronas vasotocinérgicas de esta estructura. Los resultados obtenidos sugieren que las neuronas AVT-positivas podrían derivar del dominio Supra-Opto-Paraventricular (SPV), y algunas poblaciones alcanzarían su posición definitiva dentro del propio dominio por migración radial, mientras que otras invadirían otros dominios cerebrales por migración tangencial. En conclusión, la investigación proporciona importantes datos que clarifican aspectos relevantes del desarrollo y organización adulta de la amígdala extendida, y ayuda a establecer las bases para una mejor comprensión del control neural de las emociones y el comportamiento social en condiciones normales y patológicas.

Fragmentation of massive dense cores down to <~ 1000 AU: relation between fragmentation and density structure

In order to shed light on the main physical processes controlling fragmentation of massive dense cores, we present a uniform study of the density structure of 19 massive dense cores, selected to be at similar evolutionary stages, for which their relative fragmentation level was assessed in a previous work. We inferred the density structure of the 19 cores through a simultaneous fit of the radial intensity profiles at 450 and 850 μm (or 1.2 mm in two cases) and the spectral energy distribution, assuming spherical symmetry and that the density and temperature of the cores decrease with radius following power-laws. Even though the estimated fragmentation level is strictly speaking a lower limit, its relative value is significant and several trends could be explored with our data. We find a weak (inverse) trend of fragmentation level and density power-law index, with steeper density profiles tending to show lower fragmentation, and vice versa. In addition, we find a trend of fragmentation increasing with density within a given radius, which arises from a combination of flat density profile and high central density and is consistent with Jeans fragmentation. We considered the effects of rotational-to-gravitational energy ratio, non-thermal velocity dispersion, and turbulence mode on the density structure of the cores, and found that compressive turbulence seems to yield higher central densities. Finally, a possible explanation for the origin of cores with concentrated density profiles, which are the cores showing no fragmentation, could be related with a strong magnetic field, consistent with the outcome of radiation magnetohydrodynamic simulations.

3D kinematics of the near-IR HH 223 outflow in L723

In this work, we derive the full 3D kinematics of the near-infrared outflow HH 223, located in the dark cloud Lynds 723 (L723), where a well-defined quadrupolar CO outflow is found. HH 223 appears projected on to the two lobes of the eastwest CO outflow. The radio continuum source VLA 2, towards the centre of the CO outflow, harbours a multiple system of low-mass young stellar objects. One of the components has been proposed to be the exciting source of the eastwest CO outflow. From the analysis of the kinematics, we get further evidence on the relationship between the near-infrared and CO outflows and on the location of their exciting source. The proper motions were derived using multi-epoch, narrow-band H2 (2.122 μm line) images. Radial velocities were derived from the 2.122 μm line of the spectra. Because of the extended (∼5 arcmin), S-shaped morphology of the target, the spectra were obtained with the multi-object-spectroscopy (MOS) observing mode using the instrument Long-Slit Intermediate Resolution Infrared Spectrograph (LIRIS) at the 4.2 m William Herschel Telescope. To our knowledge, this work is the first time that MOS observing mode has been successfully used in the near-infrared range for an extended target.

Functional diversity of macrophyte communities within and between Pyrenean lakes

Submersed vegetation is a common feature in about 70% Pyrene an high mountain (>1500 m a.s.l.) lakes. Isoetids and soft-water elodeids are common elements of this underw ater flora and can form distinct vegetation units (i.e. patches of vegetation dominated by different species) within complex mosaics of vegetation in shallow waters (<7 m). Since is oetids exert a strong influence on sediment biogeochemistry due to high radial oxygen loss, we examined the small scale characteristics of the lake environment (water and sediment) associated to vegetation patches in order to ascertain potential functional differences among them. To do so, we characterised the species composition and biomass of the main vegetation units from 11 lakes, defined plant communities based on biomass data, and then related each community with sediment properties (redox and dissolved nutrient concentration in the pore water) and water nutrient concentration within plant canopy. We also characterised lake water and sediment in areas without vegetation as a reference. A total of twenty-one vegetation units were identified, ranging from one to five per lake. A cluster analysis on biomass species composition suggested seven different macrophyte communities that were named after the most dominant species:Nitella sp.,Potamogeton praelongus, Myriophyllum alterniflorum, Sparganium angustifolium , Isoetes echinospora,Isoetes lacustris and Carex rostrata . Coupling between macrophyte communities and their immediate environment (overlying water and sediment) was manifested mainly as variation in sediment redox conditions and the dominant form of inorganic nitrogen in pore-water. These effects depended on the specific compositi on of the community, and on the allocation between above- and belowground biomass, and could be predicted with a model relating the average and standard deviation of sediment redox potential from 0 down to -20 cm, across macrophyte communities. Differences in pore-water total dissolved phosphorus were related to the trophic state of the lakes. There was no correlation between sediment and water column dissolved nutrients. However, nitrate concentrations tended to be lower in the water overlaying isoetid communities, in apparent contradiction to the patterns of dissolved nitrates in the pore-water. These tendencies were robust even when comparing the water over laying communities within the same lake, thus pointing towards a potential effect of isoetids in reducing dissolved nitrogen in the lakes.

El fotorreactor elíptico

In this paper, the mathematical model of the elliptical photoreactor , an special type of reactor that uses ultraviolet radiation, is presented. In the elliptical photoreactor the cylindrical reactor is irradiated from the outside by placing the lamp and the reactor at the foci of an elliptical reflector. The two main models of radiation -radial and difusse- are studied, an finally the general method of resolution of the mathematical model and its resolution in certain simple cases is shown.