Short-term evolution of forward curves and volatility in illiquid power market

We propose in this paper a model for the description of electricity spot prices, which we use to describe the dynamics of forward curves. The spot price model is based on a long-term/short-term decomposition, where the price is thought of as made up of two factors: A long-term equilibrium level and short-term movements around the equilibrium. We use a non-parametric approach to model the equilibrium level of power prices, and a mean-reverting process with GARCH volatility to describe the dynamics of the short-term component. Then, the model is used to derive the expression of the short-term dynamics of the forward curve implicit in spot prices. The rationale for the approach is that information concerning forward prices is not available in most of power markets, and the direct modeling of the forward curve is a difficult task. Moreover, power derivatives are typically written on forward contracts, and usually based on average prices of forward contracts. Then, it is difficult to obtain analytical expressions for the forward curves. The model of forward prices allows for the valuation of power derivatives, as well as the calculation of the volatilities and correlations required in risk management activities. Finally, the methodology is proven in the context of the Spanish wholesale marke

Estrogen-related genes and postmenopausal osteoporosis risk

Background To date, more than 150 candidate genes related to osteoporosis have been described, but osteoporosis has increasingly been considered a polygenic disease modulated by environmental factors. It is thought that osteoporosis predisposition, pathology, and treatment response depend on the interaction between different genes or between genes and environmental factors. Objective The aim of this study was to evaluate the relationship between the presence of single nucleotide polymorphisms (SNPs) in the estrogen metabolic pathway and the development of osteoporosis and to determine whether this relationship is monogenic or whether interactions between genes exist. Materials and methods A multicentric study with 1980 postmenopausal Spanish women in fi ve Spanish communities was conducted. The women completed a specifi c questionnaire that inquired about risk factors for osteoporosis. Data on participants ’ bone mineral density were obtained with dual-energy X-ray densitometers, and genetic data were obtained from frozen peripheral blood. Results The digenic protection combinations indicated involvement of the wild-type genotype (WT) of the 3 UTR marker for the CYP19A1 gene, the IVS4 marker of the same gene, and the BMP15 and FSHR genes. Among patients who carried two or more of the genotypes considered ‘ risky ’ , the triple combination among markers of the ESR2 and NRIP1 genes with any of the two mutations of the analyzed markers of the BMP15 gene gave a mean T -score value of 2.32 0.91 ( p 0.02). Conclusion Variants of the new candidate genes ( NRIP and BMP15 ) can predispose patients to osteoporosis

Influence of the lunar cycle on plasma melatonin, vitellogenin and sex steroids rhythms in Senegal sole, Solea senegalensis

24 p., il., y bibliografíaThe effect of the moon light cycle on plasma melatonin rhythms was examined in Senegal sole (Solea senegalensis) exposed to natural outdoor or artificial indoor lighting conditions. Furthermore, in a second experiment, the effect of the lunar cycle on vitellogenin and sex steroids (Testosterone, T; Estradiol, E2; 11-ketotestosterone, 11kt) was studied using mature individuals during reproductive season. In the first experiment, during full moon, plasma melatonin peaked at night in covered tanks (deprived of night illumination) from both outdoor (133.2 ± 12.8 pg ml-1) and indoor (190.6 ± 41.5 pg ml-1) groups. However, for fish in the open tanks, exposed to approximately 0.3 lux of illumination, nocturnal plasma melatonin was significantly reduced (p<0.05), approaching to mid-light (ML) values, (79.6 ± 7.1 and 81.8 ± 14.0 pg ml-1, for outdoor and indoor groups, respectively). During new moon a similar pattern was observed in outdoor group: fish in the covered tank showed higher melatonin values than those in the open tank, which were exposed to the near undetectable night illumination. In the second experiment, plasma sex steroid concentrations were significantly higher during the full moon compared to the new moon. In the case of females, E2 concentration reduced from 2.4 ± 0.6 to 0.4 ± 0.1 ng ml-1 between full and new moon samplings, while T decreased from 0.3 ± 0.0 to 0.2 ± 0.0 ng ml-1. Vitellogenin, however, did not show such differences between moon phases. In males, 11kt exhibited a plasma concentration of 14.3 ± 2.1 ng ml-1 during full moon and 4.7 ± 0.7 ng ml-1 during new moon while T values were 2.6 ± 0.4 and 1.0 ± 0.1 ng ml-1 for full and new moon, respectively. In conclusion, these findings pointed out the high sensitivity to moon light of the Senegal sole, which could be using the melatonin signalling to synchronize their reproduction rhythms to the lunar cycle.This work has been financed by the Spanish Ministry of Education and Science (MEC) through project Reprosolea AGL2004-07984-CO2-01/ACU to FJSV and project AGL2006-13777-C03-01 to EM. CO received an FPI fellowship from the same institution.Peer reviewe

Ethanol toxicity differs depending on the time of day

Ethanol is one of the most commonly abused drugs and consequently its toxic and psychoactive effect has been widely investigated, although little is known about the time-dependent effects of this drug. In the present research zebrafish was used to assess daily rhythms in ethanol toxicity and behavioural effects, as well as the temporal pattern of expression of key genes involved in ethanol detoxification in the liver (adh8a, adh5, aldh2.1 and aldh2.2). Our results showed marked differences in the mortality rate of zebrafish larvae depending on the time of day of the exposure to 5% ethanol for 1h (82% and 6% mortality in the morning and at night, respectively). A significant daily rhythm was detected with the acrophase located at “zeitgeber” time (ZT) = 04:22 h. Behavioural tests exposing zebrafish to 1% ethanol provoked a major decrease in swimming activity (68–84.2% reduction) at ZT2, ZT6 and ZT10. In contrast, exposure at ZT18 stimulated swimming activity (27% increase). During the day fish moved towards the bottom of the tank during ethanol exposure, whereas at night zebrafish increased their activity levels right after the exposure to ethanol. Genes involved in ethanol detoxification failed to show significant daily rhythms in LD, although all of them exhibited circadian regulation in constant darkness (DD) with acrophases in phase and located at the end of the subjective night. Taken altogether, this research revealed the importance of considering the time of day when designing and carrying out toxicological and behavioural tests to investigate the effects of ethanol, as the adverse effects of this drug were more marked when fish were exposed in the morning than at night

Effect of daily thermo- and photo-cycles of different light spectrum on the development of Senegal sole (Solea senegalensis) larvae

36 p., il., y bibliografíaThis paper investigates the impact of different thermo- and photo-cycles of distinct wavelengths on Solea senegalensis larvae from day 1 to 30 post-hatching. In experiment 1, larvae were exposed to 12h light:12h dark (12L:12D) cycle and (A) constant temperature (20.7°C), (B) thermocycle of 12h thermophase: 12h cryophase, 22.1°C day: 19.0°C night (referred to as TC) or (C) 12h cryophase: 12h thermophase, 19.2°C day: 22.0°C night (referred to as CT). In experiment 2, larvae were kept under constant temperature (20.8°C) and exposed to (A) continuous light (LL), (B) continuous darkness (DD), and LD 12L:12D cycles of (C) white light (LDW), (D) blue light (LDB) or (E) red light (LDR). The sole larvae achieved the best performance, and showed fastest development and lowest degree of deformity under natural thermocycle conditions (TC) with a deformity percentage of 31.1% and LDB cycles with 27.7% of malformation, conditions which were nearest their natural aquatic environment. Larvae reared under TC started eye migration at 9day post-hatching (DPH), while larvae exposed to CT started eye migration at 11 DPH. In larvae under the LDB treatment the migration of the eye started earlier than in the other treatments (9 DPH), while larvae reared under LL and DD photoperiods died before metamorphosis. These findings highlight the importance of light and temperature cycles during the early development of S. senegalensis larvae, which should be taken into consideration in experimental or rearing protocols.This research was funded by the Spanish Ministry of Science and Innovation (MICINN) by projects “Circasole” AGL2007-66507-C02-02 and AQUAGENOMICS 28502 (Consolider-Ingenio Program), and SENECA by project 05690/PI/07 to Francisco Javier Sánchez Vázquez.Peer reviewe

Ferrimagnetic nanostructures for magnetic memory bits

Increasing the magnetic data recording density requires reducing the size of the individual memory elements of a recording layer as well as employing magnetic materials with temperature-dependent functionalities. Therefore, it is predicted that the near future of magnetic data storage technology involves a combination of energy-assisted recording on nanometer-scale magnetic media. We present the potential of heat-assisted magnetic recording on a patterned sample; a ferrimagnetic alloy composed of a rare earth and a transition metal, DyCo$_5$, which is grown on a hexagonal-ordered nanohole array membrane. The magnetization of the antidot array sample is out-of-plane oriented at room temperature and rotates towards in-plane upon heating above its spin-reorientation temperature (T$_R$) of ~350 K, just above room temperature. Upon cooling back to room temperature (below T$_R$), we observe a well-defined and unexpected in-plane magnetic domain configuration modulating with ~45 nm. We discuss the underlying mechanisms giving rise to this behavior by comparing the magnetic properties of the patterned sample with the ones of its extended thin film counterpart. Our results pave the way for novel applications of ferrimagnetic antidot arrays of superior functionality in magnetic nano-devices near room temperature.Comment: 19 pages, 4 figure

Parámetros reproductivos y distribución geográfica potencial de las áreas de anidación de Grus canadensis nesiotes (Aves, Gruidae) en Cuba: implicaciones para su conservación

Grus canadensis nesiotes (grulla cubana) es una subespecie endémica de Cuba que se encuentra en peligro de extinción. A pesar de estar directamente relacionada con los humedales, no existen estudios que contribuyan a su gestión y conservación. Por ello, se registraron parámetros reproductivos de la subespecie durante ocho temporadas reproductivas entre 2005 y 2015 en un humedal de Cuba; asimismo, se modeló y caracterizó la distribución geográfica potencial de las áreas de anidación, y se analizó su representación dentro de las áreas protegidas (AP). Para elaborar el modelo, se utilizaron el algoritmo de máxima entropía y variables de hábitat (100  m de tamaño de píxel). Para caracterizar la distribución potencial, se calculó la superficie ocupada por cada uso de suelo y tipo de vegetación dentro de dicha área de distribución. Se empleó el mismo procedimiento para calcular la superficie de la distribución que está protegida. Se localizaron 151  nidos en herbazales de ciénaga. Se trataba de plataformas simples sobre suelo húmedo o agua; los más grandes se observaron en 2006. El 70% de los nidos tuvieron dos huevos (1,7 huevos/nido) y el 63,5% fueron exitosos con 1,6 polluelos/nido exitoso. El hábitat potencial de anidación es estrecho (242 km2) y se localiza en el centro del humedal. De la distribución prevista, la superficie con alta probabilidad de presencia es del 13,8%. El 60% del herbazal de ciénaga de la zona del estudio estaba comprendido dentro de la distribución potencial, mientras que la proporción de cultivos (1,2%) y pastizales (2,1%) era baja. Las AP gestionadas solo protegen el 39,1% de la distribución potencial de los sitios de anidación y el 12% de las zonas con alta probabilidad. Se proponen tres sitios prioritarios para estudiar la anidación de la subespecie y hacer un seguimiento de la misma. Las medidas de conservación de la subespecie deberían considerar la distribución geográfica potencial de los sitios de anidación dentro y fuera de las AP.Grus canadensis nesiotes (grulla cubana) es una subespecie endémica de Cuba que se encuentra en peligro de extinción. A pesar de estar directamente relacionada con los humedales, no existen estudios que contribuyan a su gestión y conservación. Por ello, se registraron parámetros reproductivos de la subespecie durante ocho temporadas reproductivas entre 2005 y 2015 en un humedal de Cuba; asimismo, se modeló y caracterizó la distribución geográfica potencial de las áreas de anidación, y se analizó su representación dentro de las áreas protegidas (AP). Para elaborar el modelo, se utilizaron el algoritmo de máxima entropía y variables de hábitat (100  m de tamaño de píxel). Para caracterizar la distribución potencial, se calculó la superficie ocupada por cada uso de suelo y tipo de vegetación dentro de dicha área de distribución. Se empleó el mismo procedimiento para calcular la superficie de la distribución que está protegida. Se localizaron 151  nidos en herbazales de ciénaga. Se trataba de plataformas simples sobre suelo húmedo o agua; los más grandes se observaron en 2006. El 70% de los nidos tuvieron dos huevos (1,7 huevos/nido) y el 63,5% fueron exitosos con 1,6 polluelos/nido exitoso. El hábitat potencial de anidación es estrecho (242 km2) y se localiza en el centro del humedal. De la distribución prevista, la superficie con alta probabilidad de presencia es del 13,8%. El 60% del herbazal de ciénaga de la zona del estudio estaba comprendido dentro de la distribución potencial, mientras que la proporción de cultivos (1,2%) y pastizales (2,1%) era baja. Las AP gestionadas solo protegen el 39,1% de la distribución potencial de los sitios de anidación y el 12% de las zonas con alta probabilidad. Se proponen tres sitios prioritarios para estudiar la anidación de la subespecie y hacer un seguimiento de la misma. Las medidas de conservación de la subespecie deberían considerar la distribución geográfica potencial de los sitios de anidación dentro y fuera de las AP.Reproductive parameters and potential geographical distribution of nesting areas of Grus canadensis nesiotes (Aves, Gruidae) in Cuba: conservation implications Grus canadensis nesiotes (Cuban sandhill crane) is an endemic and endangered subspecies from Cuba. Protection of wetland habitats is essential for survival of this species, but studies that could contribute to its management and conservation are lacking. In this study we recorded the reproductive parameters of Grus canadensis nesiotes in eight breeding seasons between 2005 and 2015 in a wetland of Cuba. We modeled and characterized the potential geographical distribution of the nesting areas, analyzing its representation within protected areas. Maximum entropy algorithm and habitat variables were used for modeling (100 m of pixel size). To characterize the potential distribution we calculated each land–use–vegetation within the potential distribution. We used the same procedure to determine the extent of the protected area. A hundred and fifty–one nests were located in marsh grasslands. These nests were simple platforms built on wet soil/water; the largest nests were observed in 2006. Seventy percent of nests had two eggs (1.7 eggs/nest) and 63.5% were successful with 1.6 chicks per successful nest. The potential nesting habitat is a narrow stretch (242 km2) located in the center of the wetland. The area with high probability of presence makes up 13.8% of the predicted distribution. Sixty percent of marsh grassland of the study area was included in the potential distribution, while the proportion of crops (1.2%) and pastures (2.1%) was low. Managed protected areas cover only 39.1% of the potential distribution of the nesting sites and 12% of the high probability areas. We propose three priority sites to study and monitor nesting of the subspecies. Species conservation actions should consider the potential geographical distribution of nesting sites both inside and outside the protected areas