908 research outputs found
Disempowerment and resistance in the print industry? Reactions to surveillance-capable technology
This article offers a critique of recent characterisations of the effects of electronic technologies in the workplace. It presents detailed case study evidence that calls into question a number of common theoretical assumptions about the character of surveillance at work and the responses of employees to it
UBVJHKLM photometry and modeling of R Coronae Borealis
We present the results of UBVJHKLM photometry of R CrB spanning the period
from 1976 to 2001. Studies of the optical light curve have shown no evidence of
any stable harmonics in the variations of the stellar emission. In the L band
we found semi-regular oscillations with the two main periods of ~3.3 yr and
11.9 yr and the full amplitude of ~0.8 mag and ~0.6 mag, respectively. The
colors of the warm dust shell (resolved by Ohnaka et al. 2001) are found to be
remarkably stable in contrast to its brightness. This indicates that the inner
radius is a constant, time-independent characteristic of the dust shell. The
observed behavior of the IR light curve is mainly caused by the variation of
the optical thickness of the dust shell within the interval \tau(V)= 0.2-0.4.
Anticorrelated changes of the optical brightness (in particular with P ~ 3.3
yr) have not been found. Their absence suggests that the stellar wind of R CrB
deviates from spherical symmetry. The light curves suggest that the stellar
wind is variable. The variability of the stellar wind and the creation of dust
clouds may be caused by some kind of activity on the stellar surface. With some
time lag, periods of increased mass-loss cause an increase in the dust
formation rate at the inner boundary of the extended dust shell and an increase
in its IR brightness. We have derived the following parameters of the dust
shell (at mean brightness) by radiative transfer modeling: inner dust shell
radius r_in ~ 110 R_*, temperature T_dust(r_in) ~ 860 K, dust density
\rho_dust(r_in) ~ 1.1x10^{-20} g cm^-3, optical depth \tau(V) ~ 0.32 at 0.55
micron, mean dust formation rate [dM/dt]_dust ~ 3.1x10^-9 M_sun / yr, mass-loss
rate [dM/dt]_gas ~ 2.1x10^-7 M_sun / yr, size of the amorphous carbon grains
<(~) 0.01 micron, and B-V ~ -0.28.Comment: 9 pages, 6 figures, accepted for publication in A&
The balance between fumarate and malate plays an important role in plant development and postharvest quality in tomato fruit
Organic acids, produced as intermediates of the tricarboxylic cycle, play a crucial role in the plant primary metabolism and are considered as being ones of the most important quality traits in edible fruits. Even if they are key metabolites in a multitude of cellular functions, little is known about their physiological relevance and regulation. Transgenic tomato (Solanum lycopersicum) plants expressing constitutively a bacterial maleate isomerase, which converts reversibly maleate to fumarate, were generated in order to improve our knowledge about the role of organic acids in the crop and fruit metabolism. Growth and reproduction were affected by the unbalance of tricarboxylic cycle intermediates, as a dwarf phenotype and a flowering delay were observed in the transgenic plants. In addition, a delay in chlorophyll synthesis, a decrease in the numbers of stomata and significant changes in some photosynthetic parameters indicated alterations in central primary metabolism. Postharvest was also impaired, as transgenic fruits showed increased water lost and deterioration, indicating a possible role of the organic acids in cell wall metabolism. Finally, preliminary metabolomics analysis pointed out important changes during fruit ripening in flavor-related metabolites, such as acids and sugars, revealing the importance of organic acids in fruit metabolism. Taken together, these data indicate a pivotal role of tricarboxylic cycle intermediates, such as malate or fumarate, as regulatory metabolites. Besides their role in quality fruit characteristics, they are involved in a multitude of functions including growth and photosynthesis.Universidad de MĂĄlaga. Campus de Excelencia Internacional AndalucĂa Tech
Metabolomics profiling of strawberry (Fragaria x ananassa) F1 population to characterize flavour and nutritional traits
The cultivated strawberry (Fragaria x ananassa) is a highly consumed fruit known for its delicate flavour and nutritional characteristics. However, as fruit quality attributes have been lost after years of traditional breeding, new technological tools, such as high throughput metabolomics, are necessary for the identification of factors responsible of these traits. Here we present the metabolomics profiling for the content of primary and secondary metabolites of a 95 F1 individuals strawberry population derived from genotype â1392â, selected for its superior flavour, and â232â (Zorrilla-Fontanesi et al., 2011; Zorrilla-Fontanesi et al., 2012).
Metabolite profiling was performed on mature fruits of the strawberry population using gas chromatography hyphenated to time-of-flight mass spectrometry for primary metabolites and ultra performance liquid chromatography Exactive Orbitrap tandem mass spectrometry for secondary metabolites.Universidad de MĂĄlaga. Campus de Excelencia Internacional AndalucĂa Tech
The Cepheid Phase Lag Revisited
We compute the phase lags between the radial velocity curves and the light
curves for classical Cepheid model
sequences both in the linear and the nonlinear regimes. The nonlinear phase
lags generally fall below the linear ones except for high period models where
they lie above, and of course for low pulsation amplitudes where the two merge.
The calculated phase lags show good agreement with the available observational
data of normal amplitude Galactic Cepheids. The metallicity has but a moderate
effect on the phase lag, while the mass-luminosity relation and the parameters
of the turbulent convective model (time-dependent mixing length) mainly
influence the modal selection and the period, which is then reflected in the
period -- diagram. We discuss the potential application of this
observable as a discriminant for pulsation modes and as a test for ultra-low
amplitudes (ULA) pulsation.Comment: 11 pages, 8 figures, accepted for publication in ApJ, minor revisions
in the text and figures, (black and white version available from 2nd author's
website
Polaris B, an optical companion of Polaris (alpha UMi) system: atmospheric parameters, chemical composition, distance and mass
We present an analysis of high-resolution spectroscopic observations of
Polaris B, the optical companion of the Polaris Ab system. The star has a
radial velocity V_r of -16.6km/s to -18.9km/s, and a projected rotational
velocity vsini=110 km/s. The derived atmospheric parameters are: Teff=6900K;
logg=4.3; V_t=2.5km/s. Polaris B has elemental abundances generally similar to
those of the Cepheid Polaris A (Usenko et al. 2005a), although carbon, sodium
and magnesium are close to the solar values. At a spectral type of F3V Polaris
B has a luminosity of 3.868L_sun, an absolute magnitude of +3.30mag, and a
distance of 109.5pc. The mass of the star is estimated to be 1.39M_sun, close
to a mass of 1.38+/-0.61M_sun for the recently-resolved orbital periods
companion Polaris Ab observed by Evans et al. (2007).Comment: 6 pages, 3 figures, 1 tabl
Existing data sources for clinical epidemiology: The pharmo database network
The PHARMO Database Network provides a unique opportunity to gain insight in the complete patient journey and healthcare in the Netherlands. The PHARMO Database Network is a population-based network of electronic healthcare databases and combines anonymous data from different primary and secondary healthcare settings in the Netherlands. Healthcare settings include general practitioners, out-patient and in-patient pharmacies, hospitals and clinical laboratories. Furthermore, databases are linked with external registries suc
Alteration of the interconversion of pyruvate and malate in the plastid or cytosol of ripening tomato fruit invokes diverse consequences on sugar but similar effects on cellular organic Acid, metabolism, and transitory starch accumulation
The aim of this work was to investigate the effect of decreased cytosolic phosphoenolpyruvate carboxykinase (PEPCK) and plastidic NADP-dependent malic enzyme (NADP-ME) on tomato (Solanum lycopersicum) ripening. Transgenic tomato plants with strongly reduced levels of PEPCK and plastidic NADP-ME were generated by RNA interference gene silencing under the control of a ripening-specific E8 promoter. While these genetic modifications had relatively little effect on the total fruit yield and size, they had strong effects in fruit metabolism. Both transformants were characterized by lower levels of starch at breaker stage. Analysis of the activation state of ADP-glucose pyrophosphorylase correlated with the decrease of starch in both transformats, which suggest that is due to an altered cellular redox status. Moreover, metabolic profiling and feeding experiments involving positional labelled glucoses of fruits lacking in plastidic NADP-malic enzyme and cytosolic PEPCK activities revealed differential changes in overall respiration rates and tricarboxylic acid (TCA) cycle flux. Inactivation of cytosolic PEPCK affected the respiration rate which suggests that excess of oxaloacetate OAA is converted to aspartate and reintroduced in the TCA via 2-oxoglutarate/glutamate. On the other hand, the plastidic NADP-malic enzyme antisense lines were characterized by no changes in respiration rates and TCA cycle flux and together with an increase of pyruvate kinase and phosphoenolpyruvate carboxylase activities indicates that pyruvate is supply through these enzymes to the TCA cycle. These results are discussed in the context of current models of the importance of malate during tomato fruit ripening
Reddenings of FGK supergiants and classical Cepheids from spectroscopic data
Accurate and homogeneous atmospheric parameters (Teff, log (g), Vt, [Fe/H])
are derived for 74 FGK non-variable supergiants from high-resolution, high
signal-to-noise ratio, echelle spectra. Extremely high precision for the
inferred effective temperatures (10-40 K) is achieved by using the line-depth
ratio method. The new data are combined with atmospheric values for 164
classical Cepheids, observed at 675 different pulsation phases, taken from our
previously published studies. The derived values are correlated with unreddened
B-V colours compiled from the literature for the investigated stars in order to
obtain an empirical relationship of the form: (B-V)o = 57.984 - 10.3587(log
Teff)^2 + 1.67572(log Teff)^3 - 3.356(log (g)) + 0.0321(Vt) + 0.2615[Fe/H] +
0.8833((log (g))(log Teff)). The expression is used to estimate colour excesses
E(B-V) for individual supergiants and classical Cepheids, with a precision of
+-0.05 mag. for supergiants and Cepheids with n=1-2 spectra, reaching +-0.025
mag. for Cepheids with n>2 spectra, matching uncertainties for the most
sophisticated photometric techniques. The reddening scale is also a close match
to the system of space reddenings for Cepheids. The application range is for
spectral types F0--K0 and luminosity classes I and II.Comment: accepted for publication (MNRAS
QTLs mapping for primary metabolites responsible of the organoleptic and nutritional characteristics of strawberry (Fragaria x ananassa)
The cultivated strawberry (Fragaria x ananassa) is the berry fruit most consumed worldwide and is well-known for its delicate flavour and nutritional properties. However, fruit quality attributes have been lost or reduced after years of traditional breeding focusing mainly on agronomical traits.
To face the obstacles encountered in the improvement of cultivated crops, new technological tools, such as genomics and high throughput metabolomics, are becoming essential for the identification of genetic factors responsible of organoleptic and nutritive traits. Integration of âomicsâ data will allow a better understanding of the molecular and genetic mechanisms underlying the accumulation of metabolites involved in the flavour and nutritional value of the fruit. To identify genetic components affecting/controlling? fruit metabolic composition, here we present a quantitative trait loci (QTL) analysis using a 95 F1 segregating population derived from genotypes â1392â, selected for its superior flavour, and â232â selected based in high yield (Zorrilla-Fontanesi et al., 2011; Zorrilla-Fontanesi et al., 2012). Metabolite profiling was performed on red stage strawberry fruits using gas chromatography hyphenated to time-of-flight mass spectrometry, which is a rapid and highly sensitive approach, allowing a good coverage of the central pathways of primary metabolism. Around 50 primary metabolites, including sugars, sugars derivatives, amino and organic acids, were detected and quantified after analysis in each individual of the population. QTL mapping was performed on the â232â x â1392â population separately over two successive years, based on the integrated linkage map (SĂĄnchez-Sevilla et al., 2015). First, significant associations between metabolite content and molecular markers were identified by the non-parametric test of Kruskal-Wallis. Then, interval mapping (IM), as well as the multiple QTL method (MQM) allowed the identification of QTLs in octoploid strawberry. A permutation test established LOD thresholds for each metabolite and year.
A total of 132 QTLs were detected in all the linkage groups over the two years for 42 metabolites out of 50. Among them, 4 (9.8%) QTLs for sugars, 9 (25%) for acids and 7 (12.7%) for amino acids were stable and detected in the two successive years. We are now studying the QTLs regions in order to find candidate genes to explain differences in metabolite content in the different individuals of the population, and we expect to identify associations between genes and metabolites which will help us to understand their role in quality traits of strawberry fruit.Universidad de MĂĄlaga. Campus de Excelencia Internacional AndalucĂa Tech. The work was supported by the MINECO (grant AGL2012-40066-C02-02 ; Spain). SO aknowledges the support by Spanish Ministry of Science and Innovation (RamĂłn and Cajal contract, RYC2011-09170). DP has received a predoctoral grant from MINECO (grant BES-2013-062856). JJM and IA has been supported by the grant AGL2012-40066-C02-01). The authors also aknowlegde the support by the University de MĂĄlaga, Campus de Excelencia Internacional de AndalucĂa
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