2,202 research outputs found
Early Science with the Large Millimeter Telescope: COOL BUDHIES I - a pilot study of molecular and atomic gas at z~0.2
An understanding of the mass build-up in galaxies over time necessitates
tracing the evolution of cold gas (molecular and atomic) in galaxies. To that
end, we have conducted a pilot study called CO Observations with the LMT of the
Blind Ultra-Deep H I Environment Survey (COOL BUDHIES). We have observed 23
galaxies in and around the two clusters Abell 2192 (z = 0.188) and Abell 963 (z
= 0.206), where 12 are cluster members and 11 are slightly in the foreground or
background, using about 28 total hours on the Redshift Search Receiver (RSR) on
the Large Millimeter Telescope (LMT) to measure the CO J = 1 --> 0
emission line and obtain molecular gas masses. These new observations provide a
unique opportunity to probe both the molecular and atomic components of
galaxies as a function of environment beyond the local Universe. For our sample
of 23 galaxies, nine have reliable detections (S/N3.6) of the CO
line, and another six have marginal detections (2.0 < S/N < 3.6). For the
remaining eight targets we can place upper limits on molecular gas masses
roughly between and . Comparing our results to other
studies of molecular gas, we find that our sample is significantly more
abundant in molecular gas overall, when compared to the stellar and the atomic
gas component, and our median molecular gas fraction lies about above
the upper limits of proposed redshift evolution in earlier studies. We discuss
possible reasons for this discrepancy, with the most likely conclusion being
target selection and Eddington bias.Comment: MNRAS, submitte
DISTRIBUCIÓN ESPACIAL Y FLUCTUACIÓN POBLACIONAL DE PHYLLOCOPTRUTA OLEIVORA (ASHMEAD) (ACARI: ERIOPHYIDAE) EN CÍTRICOS DE GÜEMEZ, TAMAULIPAS
The present investigation was accomplished in the county of Güemez, Tamaulipas, Mexico during the period june of 1998 to October of 1999. The objectives were to evaluate the spatial distribution and the population fluctuation of the citrus rust mite Phyllocoptruta oleivora (Ashmead). This investigation was conducted on 10 orange trees of the variety Valencia selected at random in an area of a hectarea. Each tree was divided into 7 sampling areas. Samples were taken every 14 days, using the leaf as the sample unit and counting the number of mites present on both sides of the leaves. A total of 10 leaves were observed in each of 7 sections, making a total of 70 leaves for each tree and 700 for each sampling date. Using the mean densities and the variance obtained in each sampling, a statistical analysis was conducted to determine the spatial distribution of the mite in the area study. Eight indexes were used to determine the spatial distribution. The index values of Lexis , Charlier, David & Moore, Green and the dispersion parameter (K) of negative binomial indicated a clumped distribution for this mite over all 16 sampling dates. However the values of Morisita, Iwao, and Taylor´s power law showed random distribution in two, two, and three sampling dates, respectively. In all samples, the highest mite densities were found in the middle tree stratum (with higher aggregation toward last section of tree) followed by bottom and top strata, respectively. Population peaks were found during march 27 th and september 25 th. The dependent variable used to estimate the populate on fluctuation was the mean density of the mites in each sampling date. The independent variables were: temperature, relative humidity and precipitation. A detected positive correlation between the mean density of the mites and temperatures was observed.El presente trabajo de investigación se realizó en el municipio de Güemez, México, en el periodo de Junio de 1998 a Octubre de 1999. Se determinó la distribución espacial y fluctuación poblacional del arador de los cítricos Phyllocoptruta oleivora (Ashmead). Esta investigación se realizó en 10 árboles de naranjo de la variedad Valencia, seleccionados al azar en una superficie de una hectárea. Cada árbol se dividió en 7 áreas de muestreo y se realizaron muestreos cada 14 días, tomando como unidad de muestra las hojas. En total se registró la población en 700 hojas por fecha de muestreo. De los datos obtenidos se realizaron análisis para determinar la distribución espacial que presenta el ácaro en la zona de estudio, utilizando para ello 8 índices de muestro. Se registró la fluctuación poblacional y posibles factores climáticos que pudieran limitar la densidad poblacional. Los índices de Lexis, Charlier, David y Moore, Green y el parámetro K de la binomial negativa indicaron una distribución agregada en todas las fechas de muestreo donde se detectó la presencia de ácaros. Los valores de Morisita, Iwao y la ley de poder de Taylor mostraron disposición aleatoria en dos, dos y tres de las fechas de muestro respectivamente, en las demás se presentó disposición agregada. En todos los muestreos se encontró mayor cantidad de ácaros en el estrato medio seguido del estrato inferior y superior respectivamente. Se detectaron tres picos poblacionales; el 27 de marzo, el 21 de agosto y el 25 de septiembre con promedios de 3.8, 2.9, y 4.5 ácaros por hoja respectivamente. De los factores climáticos evaluados, la temperatura fue el que presentó el coeficiente de correlación mas alto (r=0.69916)
Effectiveness of the Natura 2000 network in protecting Iberian endemic fauna
The Iberian Peninsula is a major European region of biodiversity, as it harbours more than 30% of European endemic species. Despite a number of studies having evaluated the ability of nature reserves to protect certain taxa, there is still a lack of knowledge on how Iberian endemic fauna are represented in these reserves. We detected biodiversity hotspots of Iberian endemicity and evaluated the effectiveness of the Natura 2000 network (N2000) in representing 249 endemic species from eight animal taxonomic groups (amphibians, mammals, freshwater fishes, reptiles, water beetles, butterflies, lacewings and dung beetles). We found that only the 10% of these Iberian endemic species are considered species of community interest (i.e. species included in the Annexes of the Habitats Directive). We conducted gap analyses and null models of representativeness in N2000. Generally, N2000 is effective in its representation of Iberian endemic fauna, although we detected species and few hotspots of endemism that were still not represented. It is necessary to declare a few new protected areas, thus enhancing N2000's effectiveness in the conservation of the Iberian endemic fauna. Although the aim of N2000 is to protect species listed in the Birds and Habitats Directives, the conservation status of endemic species from one of the most important areas of Europe in terms of biodiversity, could be also a concern for the European Union. Our results are useful in the context of the recent European Commission mandate calling for a ‘fitness check’ of the Birds and Habitats Directives. This approach could be also applicable to other regions with high value of endemicity.DS‐F was supported by a post‐doctoral contract funded by Universidad de Castilla‐La Mancha and the European Social Fund (ESF). PA was supported by a ‘Ramón y Cajal’ contract (RYC‐2011‐07670, MINECO). This research was partially funded by project POII11‐0277‐5747 (Junta de Castilla‐La Mancha).Peer Reviewe
Enterococcus faecalis Bacteriophage 156 Is an Effective Biotechnological Tool for Reducing the Presence of Tyramine and Putrescine in an Experimental Cheese Model
Biogenic amines (BA) – nitrogenous compounds of low molecular weight – are the result of metabolism of certain amino acids. They are biologically present in all living organisms and play essential physiological roles. However, their accumulation in foodstuffs due to the metabolic activity of certain microorganisms represents a toxicological risk. Containing such microorganisms, and with an abundance of precursor substrate amino acids, fermented foods in general, and cheeses in particular, provide an ideal matrix for the accumulation of these toxic compounds. Unfortunately, the main microorganisms responsible for BA accumulation are members of the lactic acid bacteria (LAB) group, which are also essential for the development of the organoleptic characteristics of the final product. The methods used to reduce the BA content of cheese, such as milk pasteurization, commonly fail to do so, and affect desirable non-BA-producing LAB as well. Bacteriophages have been proposed as biotechnological tools for diminishing the presence of undesirable microorganisms in dairy products. Given their specificity, they could be used to target the population of BA-producing bacteria. In this work, we aimed to explore the use of Enterococcus faecalis infecting phages as a tool to reduce the content of BA in dairy products. For this, we proceeded to the isolation and characterization of E. faecalis bacteriophage 156, a member of the family Myoviridae. Its genome was sequenced and compared with that of E. faecalis family Myoviridae phages available in public databases. Its capacity to decrease the accumulation of the BA tyramine and putrescine in an experimental laboratory-scale cheese model was proven
Coupled C, H, N, S and Fe biogeochemical cycles operating in the continental deep subsurface of the Iberian Pyrite Belt
Microbial activity is a major contributor to the biogeochemical cycles that
make up the life support system of planet Earth. A 613 m deep geomicrobiological perforation and a systematic multi-analytical characterization
revealed an unexpected diversity associated with the rock matrix microbiome that operates in the subsurface of the Iberian Pyrite Belt (IPB). Members of 1 class and 16 genera were deemed the most representative
microorganisms of the IPB deep subsurface and selected for a deeper analysis. The use of fluorescence in situ hybridization allowed not only the identification of microorganisms but also the detection of novel activities in the
subsurface such as anaerobic ammonium oxidation (ANAMMOX) and
anaerobic methane oxidation, the co-occurrence of microorganisms able to
maintain complementary metabolic activities and the existence of biofilms.
The use of enrichment cultures sensed the presence of five different complementary metabolic activities along the length of the borehole and isolated
29 bacterial species. Genomic analysis of nine isolates identified the genes
involved in the complete operation of the light-independent coupled C, H, N,
S and Fe biogeochemical cycles. This study revealed the importance of
nitrate reduction microorganisms in the oxidation of iron in the anoxic conditions existing in the subsurface of the IPBFP7 Ideas: European Research Council,
Grant/Award Number: ERC Advanced Grant
#250-35
Measurements of differential cross sections of Z/gamma*+jets+X events in proton anti-proton collisions at sqrt{s}=1.96 TeV
We present cross section measurements for Z/gamma*+jets+X production,
differential in the transverse momenta of the three leading jets. The data
sample was collected with the D0 detector at the Fermilab Tevatron proton
anti-proton collider at a center-of-mass energy of 1.96 TeV and corresponds to
an integrated luminosity of 1 fb-1. Leading and next-to-leading order
perturbative QCD predictions are compared with the measurements, and agreement
is found within the theoretical and experimental uncertainties. We also make
comparisons with the predictions of four event generators. Two
parton-shower-based generators show significant shape and normalization
differences with respect to the data. In contrast, two generators combining
tree-level matrix elements with a parton shower give a reasonable description
of the the shapes observed in data, but the predicted normalizations show
significant differences with respect to the data, reflecting large scale
uncertainties. For specific choices of scales, the normalizations for either
generator can be made to agree with the measurements.Comment: Published in PLB. 11 pages, 3 figure
Relative rates of B meson decays into psi(2S) and J/psi mesons
We report on a study of the relative rates of B meson decays into psi(2S) and
J/psi mesons using 1.3 fb^-1 of pbar p collisions at sqrt(s) = 1.96 TeV
recorded by the D0 detector operating at the Fermilab Tevatron Collider. We
observe the channels B^0_s -> psi(2S)phi, B^0_s -> J/psi phi, B^+/- -> psi(2S)
K^+/-, and B^+/- -> J/psi K^+/- and we measure the relative branching fractions
for these channels to be B(B^0_s -> psi(2S)phi)/B(B^0_s -> J/psi phi) = 0.55
+/- 0.11 (stat) +/- 0.07 (syst) +/- 0.06 (B), B(B^+/- -> psi(2S) K^+/-)/B(B^+/-
-> J/psi K^+/-) = 0.65 +/- 0.04 (stat) +/- 0.03 (syst) +/- 0.07 (B) where the
final error corresponds to the uncertainty in the J/psi and psi(2S) branching
ratio into two muons.Comment: Published in Phys. Rev. D - Rapid Communicatio
Chemical composition of juice and antihyperglycemic studies in seed of the prehispanic fruit tunillo (Stenocereus stellatus) collected in Oaxaca, Mexico
580-584Tunillo, or pitaya of august (Stenocereus stellatus) is a prehispanic fruit, endemic to the Mixteca region in Mexico and to which a lot of medicinal properties have been associated. However, there are few scientific studies regarding its characterization and use. For these reasons, in this study we carried out a chemical characterization of the juice of four-color variants as well as determine the antihyperglycemic capacity of seed. Physical and chemical characterization were carried out in juice of fruits of Stenocereus after a preselection based on pulp color. Total soluble solids, pH, titratable acidity, organic acid and betalains were quantified in juice and antihyperglycemic capacity was measured in seed. Physicochemical parameters in juice were similar in the 4 variants; regarding the content of pigments, the red variant showed the highest values as well as the highest organic acids. However, the white, orange, and red variants showed better antihyperglycemic capacity. Red tunillo is the best candidate for obtaining pigments and its higher organic acids content correlates with its lower acceptance by the local population. The seeds of the white, orange, and red colors showed promising anhyperglycemic capacity, which suggest that they should be considered for the development of antidiabetic treatments. These results contribute to the use of compex matrices considered waste products of the fruits. This would undoubtedly increase their commercial value
Challenges in QCD matter physics - The Compressed Baryonic Matter experiment at FAIR
Substantial experimental and theoretical efforts worldwide are devoted to
explore the phase diagram of strongly interacting matter. At LHC and top RHIC
energies, QCD matter is studied at very high temperatures and nearly vanishing
net-baryon densities. There is evidence that a Quark-Gluon-Plasma (QGP) was
created at experiments at RHIC and LHC. The transition from the QGP back to the
hadron gas is found to be a smooth cross over. For larger net-baryon densities
and lower temperatures, it is expected that the QCD phase diagram exhibits a
rich structure, such as a first-order phase transition between hadronic and
partonic matter which terminates in a critical point, or exotic phases like
quarkyonic matter. The discovery of these landmarks would be a breakthrough in
our understanding of the strong interaction and is therefore in the focus of
various high-energy heavy-ion research programs. The Compressed Baryonic Matter
(CBM) experiment at FAIR will play a unique role in the exploration of the QCD
phase diagram in the region of high net-baryon densities, because it is
designed to run at unprecedented interaction rates. High-rate operation is the
key prerequisite for high-precision measurements of multi-differential
observables and of rare diagnostic probes which are sensitive to the dense
phase of the nuclear fireball. The goal of the CBM experiment at SIS100
(sqrt(s_NN) = 2.7 - 4.9 GeV) is to discover fundamental properties of QCD
matter: the phase structure at large baryon-chemical potentials (mu_B > 500
MeV), effects of chiral symmetry, and the equation-of-state at high density as
it is expected to occur in the core of neutron stars. In this article, we
review the motivation for and the physics programme of CBM, including
activities before the start of data taking in 2022, in the context of the
worldwide efforts to explore high-density QCD matter.Comment: 15 pages, 11 figures. Published in European Physical Journal
- …