Preservation of a highly perishable food, watermelon juice, at and above room temperature under mild pressure (hyperbaric storage) as an alternative to refrigeration

The feasibility of food preservation under pressure (hyperbaric storage) at and above room temperatures, as an alternative to refrigeration was evaluated. Preservation of a highly perishable food, watermelon juice, was studied at pressures of 25e150 MPa and temperatures ranging 20e37 C, being compared to refrigeration and storage at atmospheric pressure at the same temperatures. Hyperbaric storage at 75 MPa (20e37 C) revealed an inhibitory effect on microbial growth, with at least an equal performance compared to refrigeration. An additional inactivation effect was verified for storage at 100 and 150 MPa, with reduction of the initial microbial counts to 1.00 Log CFU/mL for enterobacteriaceae and yeasts and moulds, and from 4.43 ± 0.04 to 3.31 ± 0.04 and 2.99 ± 0.07 Log CFU/ mL, respectively, for total aerobic mesophiles (25 C). In general, pH, titratable acidity and total soluble solids did not show a clear variation trend with pressure and no considerable differences among storage conditions were verified. Cloudiness decreased for samples stored under pressure and browning degree was in general lower in samples stored under pressure compared to refrigeration. This work demonstrates the potentiality of hyperbaric storage as a new preservation methodology, at variable (uncontrolled) room temperature without energetic costs during storage, as an alternative to refrigeration

Continental shelf off northern Chilean Patagonia: A potential risk zone for the onset of Alexandrium catenella toxic bloom?

Harmful Algal Blooms (HAB) pose a severe socio-economic problem worldwide. The dinoflagellate species Alexandrium catenella produces potent neurotoxins called saxitoxins (STXs) and its blooms are associated with the human intoxication named Paralytic Shellfish Poisoning (PSP). Knowing where and how these blooms originate is crucial to predict blooms. Most studies in the Chilean Patagonia, were focused on coastal areas, considering that blooms from the adjacent oceanic region are almost non-existent. Using a combination of field studies and modelling approaches, we first evaluated the role of the continental shelf off northern Chilean Patagonia as a source of A. catenella resting cysts, which may act as inoculum for their toxic coastal blooms. This area is characterized by a seasonal upwelling system with positive Ekman pumping during spring-summer, and by the presence of six major submarine canyons. We found out that these submarine canyons increase the vertical advection of bottom waters, and thus, significantly enhance the process of coastal upwelling. This is a previously unreported factor, among those involved in bloom initiation. This finding put this offshore area at high risk of resuspension of resting cysts of A. catenella. Here, we discuss in detail the physical processes promoting this resuspension.Harmful Algal Blooms (HAB) pose a severe socio-economic problem worldwide. The dinoflagellate species Alexandrium catenella produces potent neurotoxins called saxitoxins (STXs) and its blooms are associated with the human intoxication named Paralytic Shellfish Poisoning (PSP). Knowing where and how these blooms originate is crucial to predict blooms. Most studies in the Chilean Patagonia, were focused on coastal areas, considering that blooms from the adjacent oceanic region are almost non-existent. Using a combination of field studies and modelling approaches, we first evaluated the role of the continental shelf off northern Chilean Patagonia as a source of A. catenella resting cysts, which may act as inoculum for their toxic coastal blooms. This area is characterized by a seasonal upwelling system with positive Ekman pumping during spring-summer, and by the presence of six major submarine canyons. We found out that these submarine canyons increase the vertical advection of bottom waters, and thus, significantly enhance the process of coastal upwelling. This is a previously unreported factor, among those involved in bloom initiation. This finding put this offshore area at high risk of resuspension of resting cysts of A. catenella. Here, we discuss in detail the physical processes promoting this resuspension.Postprint2,35

A new analysis of the GJ581 extrasolar planetary system

We have done a new analysis of the available observations for the GJ581 exoplanetary system. Today this system is controversial due to choices that can be done in the orbital determination. The main ones are the ocurrence of aliases and the additional bodies - the planets f and g - announced in Vogt et al. 2010. Any dynamical study of exoplanets requires the good knowledge of the orbital elements and the investigations involving the planet g are particularly interesting, since this body would lie in the Habitable Zone (HZ) of the star GJ581. This region,for this system, is very attractive of the dynamical point of view due to several resonances of two and three bodies present there. In this work, we investigate the conditions under which the planet g may exist. We stress the fact that the planet g is intimately related with the orbital elements of the planet d; more precisely, we conclude that it is not possible to disconnect its existence from the determination of the eccentricity of the planet d. Concerning the planet f, we have found one solution with period $\approx 450$ days, but we are judicious about any affirmation concernig this body because its signal is in the threshold of detection and the high period is in a spectral region where the ocorruence of aliases is very common. Besides, we outline some dynamical features of the habitable zone with the dynamical map and point out the role played by some resonances laying there.Comment: 12 pages, 9 figure

Continuously variable true time delay optical feeder for phased array antenna employing chirped fiber gratings

In this paper we propose and demonstrate a novel approach of true-time delay (TTD) optical feeder for phased-array antennas. A continuously variable TTD is achieved by employing tunable lasers and a wide bandwidth chirped fiber grating as dispersive element. The results show that a very high resolution performance (equivalent to a 6 bit microwave phase shifter) is obtained for a L-band phased-array antenna employing narrow tuning bandwidth lasers with a wavelength stability of 0.005 nm and a 4 nm bandwidth chirped grating with dispersion 835 ps/nm

Membrane Cholesterol Strongly Influences Confined Diffusion of Prestin

Prestin is the membrane motor protein that drives outer hair cell (OHC) electromotility, a process that is essential for mammalian hearing. Prestin function is sensitive to membrane cholesterol levels, and numerous studies have suggested that prestin localizes in cholesterol-rich membrane microdomains. Previously, fluorescence recovery after photobleaching experiments were performed in HEK cells expressing prestin-GFP after cholesterol manipulations, and revealed evidence of transient confinement. To further characterize this apparent confined diffusion of prestin, we conjugated prestin to a photostable fluorophore (tetramethylrhodamine) and performed single-molecule fluorescence microscopy. Using single-particle tracking, we determined the microscopic diffusion coefficient from the full time course of the mean-squared deviation. Our results indicate that prestin undergoes diffusion in confinement regions, and that depletion of membrane cholesterol increases confinement size and decreases confinement strength. By interpreting the data in terms of a mathematical model of hop-diffusion, we quantified these cholesterol-induced changes in membrane organization. A complementary analysis of the distribution of squared displacements confirmed that cholesterol depletion reduces prestin confinement. These findings support the hypothesis that prestin function is intimately linked to membrane organization, and further promote a regulatory role for cholesterol in OHC and auditory function

Fatores edáficos determinando a ocorrência de leguminosas herbáceas em savanas amazônicas

Fatores edáficos vem sendo indicados como determinantes para a distribuição de comunidades de plantas na Amazônia. O objetivo deste estudo foi investigar quais fatores edáficos determinam a ocorrência de leguminosas herbáceas em savanas amazônicas. Para tanto, foi realizado um inventário da flora herbácea da família Leguminosae em 34 parcelas permanentes estabelecidas em duas áreas de savana de Roraima, norte da Amazônia brasileira. As espécies Chamaecrista desvauxii (24,9%), Aeschynomene histrix (15,7%) e Galactia jussiaeana (10,8%) foram as de maior índice de valor de importância. Todas com grande abundância e ampla distribuição. Os resultados indicaram baixa densidade ou ausência de indivíduos e espécies em parcelas estabelecidas em solos mal drenados (hidromórficos). Diversidade e riqueza de espécies tendeu a ser maior em habitats formados por solos bem drenados, mais férteis e com menor concentração de alumínio trocável. É sugerido que solos pobres e sazonalmente alagados reduzam as chances de ocorrência e afetem negativamente a riqueza/diversidade de leguminosas herbáceas nas áreas de savana de Roraima

Drivers for spatial, temporal and long-term trends in atmospheric ammonia and ammonium in the UK

A unique long-term dataset from the UK National Ammonia Monitoring Network (NAMN) is used here to assess spatial, seasonal and long-term variability in atmospheric ammonia (NH3: 1998–2014) and particulate ammonium(NH4+: 1999–2014) across the UK. Extensive spatial heterogeneity in NH3 concentrations is observed, with lowest annual mean concentrations at remote sites (< 0.2 μg m-3 and highest in the areas with intensive agriculture (up to 22 μg m-3), while NH4+ concentrations show less spatial variability (e.g. range of 0.14 to 1.8 μg m-3 annual mean in 2005). Temporally, NH3 concentrations are influenced by environmental conditions and local emission sources. In particular, peak NH3 concentrations are observed in summer at background sites (defined by 5 km grid average NH3 emissions < 1 kg N ha-1 yr-1 and in areas dominated by sheep farming, driven by increased volatilization of NH3 in warmer summer temperatures. In areas where cattle, pig and poultry farming is dominant, the largest NH3 concentrations are in spring and autumn, matching periods of manure application to fields. By contrast, peak concentrations of NH4+ aerosol occur in spring, associated with long-range transboundary sources. An estimated decrease in NH3 emissions by 16%between 1998 and 2014 was reported by the UK National Atmospheric Emissions Inventory. Annually averaged NH3 data from NAMN sites operational over the same period (n=59)show an indicative downward trend, although the reduction in NH3 concentrations is smaller and non-significant: Mann–Kendall (MK), -6.3 %; linear regression(LR), -3.1 %. In areas dominated by pig and poultry farming, a significant reduction in NH3 concentrations between 1998 and 2014 (MK: -22 %; LR: -21 %, annually averaged NH3/ is consistent with, but not as large as the decrease in estimated NH3 emissions from this sector over the same period (-39 %). By contrast, in cattle-dominated areas there is a slight upward trend (non-significant) in NH3 concentrations (MK: +12 %; LR: +3.6 %, annually averaged NH3, despite the estimated decline in NH3 emissions from this sector since 1998 (-11 %). At background and sheep-dominated sites, NH3 concentrations increased over the monitoring period. These increases (non-significant) at background (MK: C17 %; LR: C13 %, annually averaged data) and sheep-dominated sites (MK: +15 %; LR: +19 %, annually averaged data) would be consistent with the concomitant reduction in SO2 emissions over the same period, leading to a longer atmospheric lifetime of NH3, thereby increasing NH3 concentrations in remote areas. The observations for NH3 concentrations not decreasing as fast as estimated emission trends are consistent with a larger downward trend in annual particulate NH4+ concentrations (1999–2014: MK: -47 %; LR: -49 %, p < 0.01, n=23), associated with a lower formation of particulate NH4+ in the atmosphere from gas phase NH3