2,631 research outputs found
Combination of stable isotope analysis and chemometrics to discriminate geoclimatically and temporally the virgin olive oils from three mediterranean countries
The knowledge of the isotopic composition of virgin olive oil (VOO) allows the evaluation of authenticity and geographical origin, being an important tool against fraud. This study aimed to assess if VOOs produced in three Mediterranean regions could be discriminated on the basis of multivariate statistical analysis of geoclimatic and isotopic data. A total of 138 geo-referenced VOO samples from Portugal, France and Turkey from two different cultivation years were collected. The isotopic composition (δ13C, δ2H and δ18O) of VOOs was obtained using an elemental analyzer coupled to an isotope ratio mass spectrometer (EA-IRMS). One-way analysis of variance for δ13C, δ2H and δ18O showed some significant differences either between crop years or geoclimatic conditions. Based on multiple regression analyses using meteorological and geographical parameters, a meteoric water line for olive oil from Portugal, France and Turkey, in two harvest years, were created to assess the impact of climate change on their δ2H and δ18O values. Principal component analysis and Linear Discriminant Analysis, used to sort samples according to geoclimatic origin, performed best for French and Portuguese olive oils. In light of the results, multivariate isotopic analysis of VOO samples may discriminate not only between geoclimatic regions but also among cultivation years
Gaia-IGRINS synergy: Orbits of Newly Identified Milky Way Star Clusters
The recent exquisite Gaia astrometric, photometric, and radial velocity (RV)
measurements resulted in a substantial advancement for the determination of the
orbits for old star clusters, including the oldest Milky Way globular clusters
(MW GCs). The main goal of this paper is to use the Gaia DR3 and the VVVX
measurements to obtain the orbits for nearly a dozen new Galactic GC candidates
that have been poorly studied or previously unexplored. We use the Gaia DR3 and
VVVX databases to identify bonafide members of the Galactic GC candidates:
VVV-CL160, Patchick122, Patchick125, Patchick126, Kronberger99, Kronberger119,
Kronberger143, ESO92-18, ESO93-08, Gaia2, and Ferrero54. The relevant mean
cluster physical parameters are derived (distances, Galactic coordinates,
proper motions, RVs). We measure accurate mean RVs for the GCs VVV-CL160 and
Patchick126, using observations acquired at the Gemini-South telescope with the
IGRINS high-resolution spectrograph. Orbits for each cluster are then computed
using the GravPot16 model, assuming typical Galactic bar pattern speeds. We
reconstruct the orbits for these clusters for the first time. These include
star clusters with retrograde and prograde orbital motions, both in the
Galactic bulge and disk. Orbital properties, such as the mean time-variations
of perigalactic and apogalactic distances, eccentricities, vertical excursions
from the Galactic plane, and Z-components of the angular momentum are obtained
for our sample. Our main conclusion is that, based on the orbital parameters,
Patchick125 and Patchick126 are genuine MW bulge/halo GCs; Ferrero54, Gaia2 and
Patchick122 are MW disk GCs. The orbits of Kronberger99, Kronberger119,
Kronberger143, ESO92-18, and ESO93-08 are more consistent with old MW disk open
clusters. VVV-CL160 falls very close to the Galactic centre, but reaches larger
distances beyond the Sun, thus its origin is still unclear.Comment: 21 pages, 8 figures. Accepted for publication in A&
Phytoplankton dynamics in relation to seasonal variability and upwelling and relaxation patterns at the mouth of Ria de Aveiro (West Iberian Margin) over a four-year period
From June 2004 to December 2007, samples were weekly collected at a fixed station located at the mouth of Ria de Aveiro (West Iberian Margin). We examined the seasonal and inter-annual fluctuations in composition and community structure of the phytoplankton in relation to the main environmental drivers and assessed the influence of the oceano-graphic regime, namely changes in frequency and intensity of upwelling events, over the dynamics of the phytoplankton assemblage. The samples were consistently handled and a final subset of 136 OTUs (taxa with relative abundance > 0.01%) was subsequently submitted to various multivariate analyses. The phytoplankton assemblage showed significant changes at all temporal scales but with an overriding importance of seasonality over longer-(inter-annual) or shorter-term fluctuations (upwelling-related). Sea-surface temperature, salinity and maximum upwelling index were retrieved as the main driver of seasonal change. Seasonal signal was most evident in the fluctuations of chlorophyll a concentration and in the high turnover from the winter to spring phytoplankton assemblage. The seasonal cycle of production and succession was disturbed by upwelling events known to disrupt thermal stratification and induce changes in the phytoplankton assemblage. Our results indicate that both the frequency and intensity of physical forcing were important drivers of such variability, but the outcome in terms of species composition was highly dependent on the available local pool of species and the timing of those events in relation to the seasonal cycle. We conclude that duration, frequency and intensity of upwelling events, which vary seasonally and inter-annually, are paramount for maintaining long-term phytoplankton diversity likely by allowing unstable coexistence and incorporating species turnover at different scales. Our results contribute to the understanding of the complex mechanisms of coastal phytoplankton dynamics in relation to changing physical forcing which is fundamental to improve predictability of future prospects under climate change.Portuguese Foundation for Science and Technology (FCT, Portugal) [SFRH/BPD/ 94562/2013]; FEDER funds; national funds; CESAM [UID/AMB/50017]; FCT/MEC through national funds; FEDERinfo:eu-repo/semantics/publishedVersio
VVVX-Gaia Discovery of a Low Luminosity Globular Cluster in the Milky Way Disk
© 2020 ESOMilky Way globular clusters (MW GCs) are difficult to identify at low Galactic latitudes because of high differential extinction and heavy star crowding. The new deep near-IR images and photometry from the VISTA Variables in the Via L\'actea Extended Survey (VVVX) allow us to chart previously unexplored regions. Our long term aim is to complete the census of MW GCs. The immediate goals are to estimate the astrophysical parameters, measuring their reddenings, extinctions, distances, total luminosities, proper motions, sizes, metallicities and ages. We use the near-IR VVVX survey database, in combination with Gaia DR2 optical photometry, and with the Two Micron All Sky Survey (2MASS) photometry. We report the detection of a heretofore unknown Galactic Globular Cluster at RA = 14:09:00.0; DEC=-65:37:12 (J2000). We calculate a reddening of E(J-K_s)=(0.3 +/- 0.03) mag and an extinction of A_Ks=(0.15 +/- 0.01) mag for this new GC. Its distance modulus and corresponding distance were measured as (m-M)=(15.93 +/- 0.03) mag and D=(15.5 +/- 1.0) kpc, respectively. We estimate the metallicity and age by comparison with known GCs and by fitting PARSEC and Dartmouth isochrones, finding dex and t=(11.0 +/- 1.0) Gyr. The mean GC PMs from Gaia are mu_alpha^(star)=(-4.68 +/- 0.47) mas yr^(-1) and mu_delta=(-1.34 \pm 0.45) mas yr^(-1). The total luminosity of our cluster is estimated to be M_Ks=(-7.76 +/- 0.5) mag. We have found a new low-luminosity, old and metal-rich globular cluster, situated in the far side of the Galactic disk, at R_G=11.2 kpc from the Galactic centre, and at z=1.0 kpc below the plane. Interestingly, the location, metallicity and age of this globular cluster are coincident with the Monoceros Ring (MRi) structure.Peer reviewe
NEXT-100 Technical Design Report (TDR). Executive Summary
In this Technical Design Report (TDR) we describe the NEXT-100 detector that
will search for neutrinoless double beta decay (bbonu) in Xe-136 at the
Laboratorio Subterraneo de Canfranc (LSC), in Spain. The document formalizes
the design presented in our Conceptual Design Report (CDR): an
electroluminescence time projection chamber, with separate readout planes for
calorimetry and tracking, located, respectively, behind cathode and anode. The
detector is designed to hold a maximum of about 150 kg of xenon at 15 bar, or
100 kg at 10 bar. This option builds in the capability to increase the total
isotope mass by 50% while keeping the operating pressure at a manageable level.
The readout plane performing the energy measurement is composed of Hamamatsu
R11410-10 photomultipliers, specially designed for operation in low-background,
xenon-based detectors. Each individual PMT will be isolated from the gas by an
individual, pressure resistant enclosure and will be coupled to the sensitive
volume through a sapphire window. The tracking plane consists in an array of
Hamamatsu S10362-11-050P MPPCs used as tracking pixels. They will be arranged
in square boards holding 64 sensors (8 times8) with a 1-cm pitch. The inner
walls of the TPC, the sapphire windows and the boards holding the MPPCs will be
coated with tetraphenyl butadiene (TPB), a wavelength shifter, to improve the
light collection.Comment: 32 pages, 22 figures, 5 table
17-AAG-induced activation of the autophagic pathway in Leishmania is associated with parasite death
The heat shock protein 90 (Hsp90) is thought to be an excellent drug target against parasitic diseases. The leishmanicidal effect of an Hsp90 inhibitor, 17-N-allylamino-17-demethoxygeldanamycin (17-AAG), was previously demonstrated in both in vitro and in vivo models of cutaneous leishmaniasis. Parasite death was shown to occur in association with severe ultrastructural alterations in Leishmania, suggestive of autophagic activation. We hypothesized that 17-AAG treatment results in the abnormal activation of the autophagic pathway, leading to parasite death. To elucidate this process, experiments were performed using transgenic parasites with GFP-ATG8-labelled autophagosomes. Mutant parasites treated with 17-AAG exhibited autophagosomes that did not entrap cargo, such as glycosomes, or fuse with lysosomes. ATG5-knockout (Δatg5) parasites, which are incapable of forming autophagosomes, demonstrated lower sensitivity to 17-AAG-induced cell death when compared to wild-type (WT) Leishmania, further supporting the role of autophagy in 17-AAG-induced cell death. In addition, Hsp90 inhibition resulted in greater accumulation of ubiquitylated proteins in both WT- and Δatg5-treated parasites compared to controls, in the absence of proteasome overload. In conjunction with previously described ultrastructural alterations, herein we present evidence that treatment with 17-AAG causes abnormal activation of the autophagic pathway, resulting in the formation of immature autophagosomes and, consequently, incidental parasite death
Search for CP Violation in the Decay Z -> b (b bar) g
About three million hadronic decays of the Z collected by ALEPH in the years
1991-1994 are used to search for anomalous CP violation beyond the Standard
Model in the decay Z -> b \bar{b} g. The study is performed by analyzing
angular correlations between the two quarks and the gluon in three-jet events
and by measuring the differential two-jet rate. No signal of CP violation is
found. For the combinations of anomalous CP violating couplings, and , limits of \hat{h}_b < 0.59h^{\ast}_{b} < 3.02$ are given at 95\% CL.Comment: 8 pages, 1 postscript figure, uses here.sty, epsfig.st
Search for supersymmetry with a dominant R-parity violating LQDbar couplings in e+e- collisions at centre-of-mass energies of 130GeV to 172 GeV
A search for pair-production of supersymmetric particles under the assumption
that R-parity is violated via a dominant LQDbar coupling has been performed
using the data collected by ALEPH at centre-of-mass energies of 130-172 GeV.
The observed candidate events in the data are in agreement with the Standard
Model expectation. This result is translated into lower limits on the masses of
charginos, neutralinos, sleptons, sneutrinos and squarks. For instance, for
m_0=500 GeV/c^2 and tan(beta)=sqrt(2) charginos with masses smaller than 81
GeV/c^2 and neutralinos with masses smaller than 29 GeV/c^2 are excluded at the
95% confidence level for any generation structure of the LQDbar coupling.Comment: 32 pages, 30 figure
- …