Control of fructose 2,6-bisphosphate levels in rat macrophages by glucose and phorbol ester

AbstractThe presence of fructose 2,6-bisphosphate (Fru 2,6-P2) in elicited peritoneal macrophages of rat was examined. These cells possess an active phosphofructokinase-2 which is diminished by citrate and only slightly inhibited by glycerol 3-phosphate. Phosphofructokinase-1 submaximal activity was increased 26-fold by the addition of 1 μM Fru 2,6-P2. Incubation of cells without glucose decreased the amount of Fru 2,6-P2 to zero, but further addition of 5 mM glucose increased the levels of the sugar ester 20-fold. In addition, the presence of phorbol ester potentiated the synthesis of Fru 2,6-P2. By contrast phenylisopropyladenosine or prostaglandin F2α inhibited the production of Fru 2,6-P2

Using a Gridded Global Dataset to Characterize Regional Hydroclimate in Central Chile

Central Chile is facing dramatic projections of climate change, with a consensus for declining precipitation, negatively affecting hydropower generation and irrigated agriculture. Rising from sea level to 6000 m within a distance of 200 km, precipitation characterization is difficult because of a lack of long-term observations, especially at higher elevations. For understanding current mean and extreme conditions and recent hydroclimatological change, as well as to provide a baseline for downscaling climate model projections, a temporally and spatially complete dataset of daily meteorology is essential. The authors use a gridded global daily meteorological dataset at 0.25° resolution for the period 1948–2008, adjusted by monthly precipitation observations interpolated to the same grid using a cokriging method with elevation as a covariate. For validation, daily statistics of the adjusted gridded precipitation are compared to station observations. For further validation, a hydrology model is driven with the gridded 0.25° meteorology and streamflow statistics are compared with observed flow. The high elevation precipitation is validated by comparing the simulated snow extent to Moderate Resolution Imaging Spectroradiometer (MODIS) images. Results show that the daily meteorology with the adjusted precipitation can accurately capture the statistical properties of extreme events as well as the sequence of wet and dry events, with hydrological model results displaying reasonable agreement with observed streamflow and snow extent. This demonstrates the successful use of a global gridded data product in a relatively data-sparse region to capture hydroclimatological characteristics and extremes

Astrometric Effects of a Stochastic Gravitational Wave Background

A stochastic gravitational wave background causes the apparent positions of distant sources to fluctuate, with angular deflections of order the characteristic strain amplitude of the gravitational waves. These fluctuations may be detectable with high precision astrometry, as first suggested by Braginsky et al. in 1990. Several researchers have made order of magnitude estimates of the upper limits obtainable on the gravitational wave spectrum \Omega_gw(f), at frequencies of order f ~ 1 yr^-1, both for the future space-based optical interferometry missions GAIA and SIM, and for VLBI interferometry in radio wavelengths with the SKA. For GAIA, tracking N ~ 10^6 quasars over a time of T ~ 1 yr with an angular accuracy of \Delta \theta ~ 10 \mu as would yield a sensitivity level of \Omega_gw ~ (\Delta \theta)^2/(N T^2 H_0^2) ~ 10^-6, which would be comparable with pulsar timing. In this paper we take a first step toward firming up these estimates by computing in detail the statistical properties of the angular deflections caused by a stochastic background. We compute analytically the two point correlation function of the deflections on the sphere, and the spectrum as a function of frequency and angular scale. The fluctuations are concentrated at low frequencies (for a scale invariant stochastic background), and at large angular scales, starting with the quadrupole. The magnetic-type and electric-type pieces of the fluctuations have equal amounts of power.Comment: 23 pages, 2 figures, references added and minor text correction

Towards On-Chip Self-Referenced Frequency-Comb Sources Based on Semiconductor Mode-Locked Lasers.

Miniaturization of frequency-comb sources could open a host of potential applications in spectroscopy, biomedical monitoring, astronomy, microwave signal generation, and distribution of precise time or frequency across networks. This review article places emphasis on an architecture with a semiconductor mode-locked laser at the heart of the system and subsequent supercontinuum generation and carrier-envelope offset detection and stabilization in nonlinear integrated optics

Gyrokinetic studies of core turbulence features in ASDEX Upgrade H-mode plasmas

Gyrokinetic validation studies are crucial in developing confidence in the model incorporated in numerical simulations and thus improving their predictive capabilities. As one step in this direction, we simulate an ASDEX Upgrade discharge with the GENE code, and analyze various fluctuating quantities and compare them to experimental measurements. The approach taken is the following. First, linear simulations are performed in order to determine the turbulence regime. Second, the heat fluxes in nonlinear simulations are matched to experimental fluxes by varying the logarithmic ion temperature gradient within the expected experimental error bars. Finally, the dependence of various quantities with respect to the ion temperature gradient is analyzed in detail. It is found that density and temperature fluctuations can vary significantly with small changes in this parameter, thus making comparisons with experiments very sensitive to uncertainties in the experimental profiles. However, cross-phases are more robust, indicating that they are better observables for comparisons between gyrokinetic simulations and experimental measurements

Estudio morfométrico de las abejas andaluzas

The biological and behavioral characteristics of the iberian bees are much less known than the other european races. This paper studies the morphological characteristics (Proboscis length; Forewing length; Forewing width; Cubital vein a; Cubital vein b; Cubital index a/b; Hindwing length; Hindwing width; Femur length; Tibia length; Metatarsus length; Metatarsus width; Width of tomentum at tergite 4; Pigmentation of tergite 3) of bees used in andalusian apiculture. Our results coincide with those described for Apis mellifera iberica.Las características biológicas y de comportamiento que presentan las abejas de la península ibérica son menos conocidas que las que presentan otras razas europeas. En el presente trabajo estudiamos las características morfológicas (longitud de la proboscis; longitud del ala delantera derecha; anchura del ala delantera derecha; vena cubital a; vena cubital b; índice cubital a/b; longitud del ala trasera derecha; anchura del ala trasera derecha; longitud del fémur; longitud de la tibia; longitud del metatarso; anchura del metatarso; longitud del tomentun del terguito 4º y pigmentación del terguito 3º) que presentan las abejas empleadas en la apicultura andaluza. Nuestros resultados coinciden con los descritos para Apis mellifera iberica

Abejas, apicultura y el nuevo mundo

In the New World, some stingless bees were kept by the native population. In Central America, maya beekeepers worked with Mellipona beecheii, in Yucatan and adjacent regions. The arrival in North America of the first beehives was in 1691 and it were sent to Virginia by the Council of the Virginia Company in London. Concerning the introduction to Central and South America the first ones arrived from Spain and Portugal towards the end of the 18th century, probably to Brazil. Prior to 1800, the european breeds taken to America were probably Apis mellifera mellifera and Apis mellifera iberica. At the turn of the century, a new european breed was imported from Italy (Apis mellifera ligustica). American apiculture has used these breeds and crossbreeds virtually up to the present day. In 1956, tropical african queens of the breed Apis mellifera scutellata were introduced to Brazil. Its crosses involving european breeds gave rise to africanized bees, which have spread over almost the whole of South, Central and North America.Los nativos del Nuevo Mundo utilizaban algunas abejas sin aguijón. En América Central los apicultores mayas trabajaron, en el Yucatán y regiones adyacentes, con Mellipona beecheii. Los nativos del Nuevo Mundo utilizaban algunas abejas sin aguijón. En América Central los apicultores mayas trabajaron, en el Yucatán y regiones adyacentes, con Mellipona beecheii. La llegada a América del Norte de las primeras colmenas se produjo en 1691. Fueron enviadas a Virginia desde Inglaterra por la Virginia Company. Las primeras colmenas enviadas a América Central y del Sur, probablemente a Brasil, a finales del siglo XVIII, procedían de España y Portugal. Antes de 1800 las razas europeas llevadas a Amé-rica fueron, probablemente, Apis mellifera mellifera y Apis mellifera iberica. A fin de siglo se introduce otra (Apis mellifera ligustica) procedente de Italia. La apicultura americana ha empleado las razas mencionadas y sus cruces, hasta nuestros días. En 1956 se introdujeron en Brasil reinas de Apis mellifera scutellata, procedentes de Africa tropical. Las abejas procedentes de su cruce con razas europeas, “africanizadas”, se han extendido por casi la totalidad del continente americano