1,149 research outputs found
Aysheaia prolata from the Wheeler Formation (Cambrian, Drumian) is a frontal appendage of the radiodontan Stanleycaris
Aysheaia prolata Robison, 1985, was described as the only lobopodian from the Cambrian (Drumian) Wheeler
Formation in Utah, and the sole representative of this genus besides the type species Aysheaia pedunculata,
from the Cambrian (Stage 5) Stephen Formation, British Columbia. A redescription of Aysheaia prolata reveals
previously overlooked morphological features, including segmental boundaries between putative lobopods, and
curved terminal spines on the putative anterior end. These observations undermine lobopodian affinities of
Aysheaia prolata, and instead we interpret this specimen as an isolated radiodontan frontal appendage. The
presence of 11 podomeres, five of which possess elongate and anteriorly recurved ventral blades with auxiliary
spines, together with shorter robust dorsal spines, identify the specimen as Stanleycaris Caron et al., 2010. This
represents the first report of Stanleycaris outside of the Cambrian (Stage 5) thin Stephen Formation in British
Columbia, expanding its palaeobiogeographic and stratigraphic range. Aysheaia is left as a monotypic genus
endemic to the Burgess Shale. The Spence Shale luolishaniid Acinocrinus stichus is currently the only
lobopodian known from the Cambrian of Utah
Knowledge, Learning and Development: the Challenge of Small and Medium Enterprises to Global Competition
Perceived value of advanced mobile messaging services: A cross-cultural comparison of Greek and Spanish users
Purpose
The purpose of this paper is to analyse the role of perceived value on post-acceptance behaviour for users of advanced mobile messaging services (AMMS). The paper also compares differences in the influence of perceived value on satisfaction and of satisfaction on loyalty to AMMS in Spain and Greece, to test the moderating effect of culture.
Design/methodology/approach
Partial least squares path modelling is used to test the model. Perceived value is modelled as a multidimensional reflective construct with four dimensions. Culture is studied at a national level. Differences between countries are tested using the multigroup analysis approach proposed by Henseler et al. (2009).
Findings
Perceived value contributes significantly to satisfaction. Satisfaction also has a significant effect on loyalty. Regarding the moderating effect of culture, the influence of perceived value on satisfaction is higher in Greece than in Spain. The authors report similar findings for the effect of satisfaction on loyalty, demonstrating the relevant moderating role of cultures with different degrees of masculinity, uncertainty avoidance and collectivism.
Practical implications
This cross-cultural comparison enables mobile phone companies to understand how to provide the greatest value with AMMS in each country in order to increase user satisfaction and loyalty to the service.
Originality/value
This is one of the first studies that develops cross-cultural research to analyse the post-acceptance of mobile services. It analyses the effect of perceived value and satisfaction, making an original comparison of two countries generally considered too similar to be compared
Dating young open clusters using delta Scuti stars. Results for Trumpler 10 and Praesepe
Aims. The main goal of this work is to date young open clusters using
Sct stars. Seismic indices such as the large separation and the
frequency at maximum power can help to constrain the models to better
characterise the stars. We propose a reliable method to identify some radial
modes, which gives us greater confidence in the constrained models. Methods. We
extract the frequency content of a sample of Sct stars belonging to
the same open cluster. We estimate the low-order large separation by means of
different techniques and the frequency at maximum power for each member of the
sample. We use a grid of models built with the typical parameters of
Sct stars, including mass, metallicity and rotation as independent variables,
and determine the oscillation modes. We select the observed frequencies whose
ratios match those of the models. Once we find a range of radial modes matching
the observed frequencies, mainly the fundamental mode, we add it to the other
seismic parameters to derive the stellar age. Assuming star groups have similar
chemistry and age, we estimate their mean age by computing a weighted
probability density function fit to the age distribution of the seismically
constrained models. Results. We estimate the age of Trumpler 10 to be
Myr, and that of Praesepe to be Myr. In this
latter case, we find two apparent populations of Sct stars in the same
cluster, one at Myr and another at Myr. This may be
due to two different formation events, different rotational velocities of the
members in our sample of stars (as rapid rotation may modify the observed large
separation), or to membership of unresolved binary systems.Comment: 20 pages, 25 figure, uses the open-source code MultiModes (see
https://github.com/davidpamos/MultiModes). It will be published in A&
Bobwhite Response to Cattle Grazing in South Texas
Range management practices to improve habitat for wildlife by reducing brush and increasing herbaceous plants, coupled with reduced stocking rates, can lead to dense stands of dominant grasses, such as four-flower trichloris (Trichloris pluriflora). This monoculture of trichloris creates dense vegetation unsuitable for northern bobwhite (Colinus virginianus; hereafter, bobwhite), reduces plant species diversity, and alters ecosystem functions. The objectives of this study are to 1) evaluate the effects of a proper cattle grazing regime to improve bobwhite habitat and 2) develop a management guide documenting how cattle grazing can be used as a tool to reduce the density and cover of dominant grasses and thereby allow higher plant species richness. The study is taking place in Duval County, Texas, USA, between 2 pastures with a combined area of 2,500 ha. One pasture serves as the control (1,337 ha) while the other (1,109 ha) is grazed to maintain a stubble height of 30–40 cm. We placed 10 grazing exclosures and 10 25-m transects within each treatment to determine botanical composition and cover. Double sampling is conducted monthly to determine forage standing crop. Forage standing crop, plant species richness, total ground cover, and forage utilization will be estimated. We hypothesize that 1) the grazed pasture will contain more bobwhites than the nongrazed pasture, 2) plant species richness will be greater in the grazed pasture, and 3) grazing will reduce the cover of trichloris. In 2020, plant species richness varied among sampling periods and was recorded as 7.5 species/transect and 4.8 species/transect higher in the nongrazed control compared to the grazed pasture in June and August, respectively. After the end of the first year of grazing, however, there was no statistical difference in plant species richness between the 2 pastures, a result that does not coincide with our second hypothesis. Litter cover did not vary among sampling periods in the nongrazed pasture but changed in the grazed pasture. Litter cover was 9.4%, 14.3%, 14.6%, and 8.9% higher in the grazed pasture than in the nongrazed pasture in May, August, September, and December 2020, respectively. Bare ground cover changed throughout sampling periods in the nongrazed and grazed pastures. Bare ground cover was 22%, 18%, and 22% higher in the grazed pasture than in the nongrazed pasture in May, September, and December 2020, respectively. Trichloris cover did not change throughout the sampling period in the grazed pasture but varied in the nongrazed pasture. Trichloris cover was 31%, 20%, 37.5%, and 35.3% higher in the nongrazed pasture than in the grazed pasture in May, August, September, and December 2020, respectively; these results support our third hypothesis. We began the cattle grazing in May 2020 with a herd of 228 mother cows placed in the grazing treatment. After 109 days of grazing, the pasture reached the target stubble height and the herd was removed. In 2021 we began grazing in June with a herd of 337 stocker calves. Vegetation growth outpaced what the calves could eat, so we removed them after 56 days and added 300 bred cows. These mother cows grazed for another 96 days until the current utilization rate was met. We completed aerial surveys for both 2020 and 2021, and the results indicate that bobwhite density on the grazed pasture was about 80% higher in 2020 and 25% higher in 2021 compared to the nongrazed pasture. These findings are consistent with our first hypothesis. In theory, by reducing the trichloris cover and increasing bare ground, we are creating more usable space for bobwhites; consequently, we are recording more bobwhites in the grazed pasture. The results are preliminary, but our study has the potential to shed light on bobwhite responses to proper cattle grazing and in turn to inform decisions about managing bobwhite habitat across South Texas
In vivo activity of plant-based interleukin-12 in the lung of Balb/c mouse
<p>Abstract</p> <p>Background</p> <p>In the last years, plants are being used for the production of a wide variety of biopharmaceuticals, including cytokines, and have the potential to serve as vehicles for mucosal administration of these molecules. We had previously reported the expression of a cytokine, interleukin-12 (IL-12), in transgenic tomato plants and had demonstrated that it retained its biologic activity <it>in vitro</it>.</p> <p>Findings</p> <p>In this work, we administered crude extracts of IL-12-containing tomato fruits to mice through the intratracheal route, measuring endogenous IL-12 and determining biologic activity by quantification of interferon-gamma (IFN-γ) in lungs and by histological analysis. IFN-γ expression in lungs, as well as histological analysis, indicate that tomato-expressed IL-12 retains its biologic activity and, most importantly, its effects are restricted to the site of administration.</p> <p>Conclusion</p> <p>Our results indicate that the functional activity of tomato-expressed IL-12 is comparable to that of commercial recombinant IL-12 when given via the mucosal route. This opens the possibility of using crude extracts prepared from tomatoes expressing IL-12 for certain immunotherapies.</p
Thrombosed great saphenous vein aneurysm accompanied by venous thrombosis
Superficial venous aneurysms of the lower extremities are considered rare and their clinical significance is poorly defined. The purpose of this article is to report a case of a 72- year-old woman with a thrombosed great saphenous vein aneurysm along with deep venous thrombosis and review its clinical presentation, diagnosis and treatment
Determinación del contenido de compuestos fenólicos presentes en extractos alcohólicos de semilla de chía (Salvia hispánica L.)
La semilla de chía (Salvia hispánica L.) es considerada alimento funcional debido a su contenido de compuestos bioactivos. El objetivo de este estudio fue determinar el contenido de compuestos fenólicos presentes en extractos alcohólicos de semilla de chía cultivada en el estado de Jalisco, México. Se realizaron extracciones metanólicas y etanólicas. Los polifenoles totales y flavonoides fueron cuantificados como equivalentes de ácido galico y como porcentaje de quercetina, respectivamente. Los compuestos fenólicos: ácido cafeico, ácido clorogénico, miricetina, quercetina y kaempferol, se cuantificaron mediante cromatografía líquida de alta resolución (HPLC), tanto para la forma libre de los antioxidantes (agliconas), como para los conjugados con azúcar (glicósidos), mediante una hidrólisis ácida. El extracto metanólico presentó la mayor cantidad de flavonoides y el etanólico de polifenoles totales. Se encontraron polifenoles en forma de agliconas y glicósidos. Los ácidos clorogénico y cafeico se encontraron en forma libre, mientras que la mayor parte de los flavonoles (miricetina, kaempferol y quercetina) fueron encontrados en forma de glicósido en los extractos. De acuerdo con lo anterior, la chía puede ser considerada como un buen componente de la dieta ya que presenta alto contenido de compuestos fenólicos
Papel del método biplot canónico en el estudio de compuestos volátiles en quesos de composición variable
The canonical biplot method (CB) is used to determine the discriminatory power of volatile chemical compounds in cheese. These volatile compounds were used as variables in order to differentiate among 6 groups or populations of cheeses (combinations of two seasons (winter and summer) with 3 types of cheese (cow, sheep and goat’s milk). We analyzed a total of 17 volatile compounds by means of gas chromatography coupled with mass detection. The compounds included aldehydes and methyl-aldehydes, alcohols (primary, secondary and branched chain), ketones, methyl-ketones and esters in winter (WC) and summer (SC) cow’s cheeses, winter (WSh) and summer (SSh) sheep’s cheeses and in winter (WG) and summer (SG) goat’s cheeses. The CB method allows differences to be found as a function of the elaboration of the cheeses, the seasonality of the milk, and the separation of the six groups of cheeses, characterizing the specific volatile chemical compounds responsible for such differences.El m.todo biplot can.nico (CB) se utiliza para determinar el poder discriminatorio de compuestos qu.micos vol.tiles en queso. Los compuestos vol.tiles se utilizan como variables con el fin de diferenciar entre los 6 grupos o poblaciones de quesos (combinaciones de dos temporadas (invierno y verano) con 3 tipos de queso (vaca, oveja y cabra). Se analizan un total de 17 compuestos vol.tiles por medio de cromatograf.a de gases acoplada con detecci.n de masas. Los compuestos incluyen aldeh.dos y metil-aldeh.dos, alcoholes (primarios de cadena, secundaria y ramificada), cetonas, metil-cetonas y .steres. Los seis grupos de quesos son, quesos de vaca de invierno (WC) y verano (SC); quesos de oveja de invierno (WSh) y verano (SSh) y quesos de cabra de invierno (WG) y verano (SG). El m.todo CB permite la separaci.n de los seis grupos de quesos y encontrar las diferencias en funci.n del tipo y estacionalidad de la leche, caracterizando los compuestos qu.micos vol.tiles espec.ficos responsables de tales diferencias
Diversity of HLA Class I and Class II blocks and conserved extended haplotypes in Lacandon Mayans.
Here we studied HLA blocks and haplotypes in a group of 218 Lacandon Maya Native American using a high-resolution next generation sequencing (NGS) method. We assessed the genetic diversity of HLA class I and class II in this population, and determined the most probable ancestry of Lacandon Maya HLA class I and class II haplotypes. Importantly, this Native American group showed a high degree of both HLA homozygosity and linkage disequilibrium across the HLA region and also lower class II HLA allelic diversity than most previously reported populations (including other Native American groups). Distinctive alleles present in the Lacandon population include HLA-A*24:14 and HLA-B*40:08. Furthermore, in Lacandons we observed a high frequency of haplotypes containing the allele HLA-DRB1*04:11, a relatively frequent allele in comparison with other neighboring indigenous groups. The specific demographic history of the Lacandon population including inbreeding, as well as pathogen selection, may have elevated the frequencies of a small number of HLA class II alleles and DNA blocks. To assess the possible role of different selective pressures in determining Native American HLA diversity, we evaluated the relationship between genetic diversity at HLA-A, HLA-B and HLA-DRB1 and pathogen richness for a global dataset and for Native American populations alone. In keeping with previous studies of such relationships we included distance from Africa as a covariate. After correction for multiple comparisons we did not find any significant relationship between pathogen diversity and HLA genetic diversity (as measured by polymorphism information content) in either our global dataset or the Native American subset of the dataset. We found the expected negative relationship between genetic diversity and distance from Africa in the global dataset, but no relationship between HLA genetic diversity and distance from Africa when Native American populations were considered alone
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