7,568 research outputs found
Identities of Choi-Lee-Srivastava involving the Euler-Mascheroni’s constant
We give an elementary deduction of the Choi-Lee-Srivastava’s identities involving the Euler Mascheroni’s constant, thus from them is immediate the identity of Wilf
Análisis de la superficie de cultivo para la producción de bioplásticos
El presente trabajo establece el potencial de mercado de los Bioplásticos (BPL), en tres escenarios: Escenario CB (crecimiento bajo), Escenario CM (crecimiento medio) y Escenario CR (crecimiento rápido). El objetivo final es Obtener las superficies de cultivo necesarias para satisfacer la demanda de las empresas productoras de BPL, según los tres escenarios. Las regiones geográficas estudiadas son: La Unión Europea (UE-27), Estados Unidos (EE.UU) y la región de Asia-Pacífico, entendiéndose, que esta última región comprende la parte del Centro, Este y Sur de Asia, además de Australia y Nueva Zelanda. Son las principales zonas donde se encuentran las empresas productoras de los BPL estudiados. Más del 95% de los BPL son elaborados en estas regiones. Se han realizado tres proyecciones para los años 2010, 2015 y 2020
Auxiliary System for Chemical and Production Data Analysis: ANAGEOT
This paper describes a computational tool developed to aid the analysis of chemical, isotopic and production data of geothermal wells. ANAGEOT is an interactive and user-friendly software that allows quickly and efficient manner, modification, retrieval and visualization of the wide amounts of data involved in the study of reservoirs. ANAGEOT optimizes time and resources, due to high quantity of historical data of most of the wells of various petroleum and geothermal fields which involve information sometimes of very long time periods. The system has the flexibility to work with different fields, considering a database for each one A very important feature of this tool is that the reports, charts and graphs are generated in a way which can be edited at any time. Similarly these can be used as source files for other applications, because they are generated in wide commercial use applications such as Microsoft Word, Excel and Golden Grapher
Brenneria quercina and Serratia spp. isolated from Spanish oak trees: molecular characterization and PCR development
Brenneria quercina has been reported as one of the causal agents of oak decline in Spain. To investigate the bacterial variability of this pathogen from different Spanish oak forests, a collection of 38 bacterial isolates from seven geographic locations and from different oak species was analysed by sequencing 16S rDNA and rep-PCR fingerprinting. All Spanish isolates of B. quercina were grouped by rep-PCR into a homogenous cluster that differed significantly from B. quercina reference strains from California. 16S rDNA analysis revealed that 34 out of 38 isolates were Brenneria . However, four isolates belonged to the genus Serratia , suggesting that this bacterium could cause cankers in oak trees. The information obtained by rep-PCR fingerprint analysis was used to develop PCR primers for the sensitive and specific detection of B. quercina from infected plant tissues. Pathogenicity tests performed with Brenneria and Serratia isolates showed that both were able to grow and cause cankers in oak trees
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Towards Pluralistic Value Alignment: Aggregating Value Systems through ℓp-Regression
Dealing with the challenges of an interconnected globalised world requires to handle plurality. This is no exception when considering value-aligned intelligent systems, since the values to align with should capture this plurality. So far, most literature on value-alignment has just considered a single value system. Thus, this paper advances the state of the art by proposing a method for the aggregation of value systems. By exploiting recent results in the social choice literature, we formalise our aggregation problem as an optimisation problem. We then cast such problem as an ℓp-regression problem. By doing so, we provide a general theoretical framework to model and solve the above-mentioned problem. Our aggregation method allows us to consider a range of ethical principles, from utilitarian (maximum utility) to egalitarian (maximum fairness). We illustrate the aggregation of value systems by considering real-world data from the European Values Study and we show how different consensus value systems can be obtained depending on the ethical principle of choice
POISSON project - II - A multi-wavelength spectroscopic and photometric survey of young protostars in L 1641
Characterising stellar and circumstellar properties of embedded young stellar
objects (YSOs) is mandatory for understanding the early stages of the stellar
evolution. This task requires the combination of both spectroscopy and
photometry, covering the widest possible wavelength range, to disentangle the
various protostellar components and activities. As part of the POISSON project,
we present a multi-wavelength spectroscopic and photometric investigation of
embedded YSOs in L1641, aimed to derive the stellar parameters and evolutionary
stages and to infer their accretion properties. Our database includes
low-resolution optical-IR spectra from the NTT and Spitzer (0.6-40 um) and
photometric data covering a spectral range from 0.4 to 1100 um, which allow us
to construct the YSOs spectral energy distributions (SEDs) and to infer the
main stellar parameters. The SED analysis allows us to group our 27 YSOs into
nine Class I, eleven Flat, and seven Class II objects. However, on the basis of
the derived stellar properties, only six Class I YSOs have an age of ~10^5 yr,
while the others are older 5x10^5-10^6 yr), and, among the Flat sources, three
out of eleven are more evolved objects (5x10^6-10^7 yr), indicating that
geometrical effects can significantly modify the SED shapes. Inferred mass
accretion rates (Macc) show a wide range of values (3.6x10^-9 to 1.2x10^-5
M_sun yr^-1), which reflects the age spread observed in our sample. Average
values of mass accretion rates, extinction, and spectral indices decrease with
the YSO class. The youngest YSOs have the highest Macc, whereas the oldest YSOs
do not show any detectable jet activity in either images and spectra. We also
observe a clear correlation among the YSO Macc, M*, and age, consistent with
mass accretion evolution in viscous disc models.Comment: 61 pages, 16 figures; A&A in pres
Star and protoplanetary disk properties in Orion's suburbs
(Note: this is a shortened version of the original "structured" A&A format
abstract.) We performed a large optical spectroscopic and photometric survey of
the Lynds~1630N and 1641 clouds. We provide a catalog of 132 confirmed young
stars in L1630N and 267 such objects in L1641. We identify 28 transition disk
systems, 20 of which were previously unknown, as well as 42 new transition disk
candidates for which we have broad-band photometry but no optical spectroscopy.
We estimate mass accretion rates M_acc from the equivalent widths of the
H_alpha, H_beta, and HeI 5876\AA emission lines, and find a dependence on
stellar mass of M_acc propto Mstar^alpha, with alpha~3.1 in the subsolar mass
range that we probe. An investigation of a large literature sample of mass
accretion rate estimates yields a similar slope of alpha~2.8 in the subsolar
regime, but a shallower slope of alpha~2.0 if the whole mass range of 0.04
M_sun-5 Msun is included. Among the transition disk objects, the fraction of
stars that show significant accretion activity is relatively low compared to
stars with still optically thick disks (26\pm11% vs. 57\pm6%, respectively).
However, those transition disks that do show significant accretion have the
same median accretion rate as normal optically thick disks of 3-4*10^{-9}
M_sun/yr. We find that the ages of the transition disks and the WTTSs without
disks are statistically indistinguishable, and both groups are significantly
older than the CTTSs. These results argue against disk-binary interaction or
gravitational instability as mechanisms causing a transition disk appearance.
Our observations indicate that disk lifetimes in the clustered population are
shorter than in the distributed population. We propose refined Halpha
equivalent width criteria to distinguish WTTSs from CTTSs.Comment: 52 pages, 16 tables, 29 figures. Accepted by A&A. Table numbering
error correcte
Epidemiology and molecular characterization of Carnivore protoparvovirus-1 infection in the wild felid Leopardus guigna in Chile
Landscape anthropization has been identified as one of the main drivers of pathogen emergence worldwide, facilitating pathogen spillover between domestic species and wildlife. The present study investigated Carnivore protoparvovirus-1 infection using molecular methods in 98 free-ranging wild guignas (Leopardus guigna) and 262 co-occurring owned, free-roaming rural domestic cats. We also assessed landscape anthropization variables as potential drivers of infection. Protoparvovirus DNA was detected in guignas across their entire distribution range, with observed prevalence of 13.3% (real-time PCR) and 9% (conventional PCR) in guignas, and 6.1% (conventional PCR) in cats. Prevalence in guigna did not vary depending on age, sex, study area or landscape variables. Prevalence was higher in juvenile cats (16.7%) than in adults (4.4%). Molecular characterization of the virus by amplification and sequencing of almost the entire vp2 gene (1, 746 bp) from one guigna and five domestic cats was achieved, showing genetic similarities to canine parvovirus 2c (CPV-2c) (one guigna and one cat), feline panleukopenia virus (FPV) (one cat), CPV-2 (no subtype identified) (two cats), CPV-2a (one cat). The CVP-2c-like sequence found in a guigna clustered together with domestic cat and dog CPV-2c sequences from South America, suggesting possible spillover from a domestic to a wild species as the origin of infection in guigna. No clinical signs of disease were found in PCR-positive animals except for a CPV-2c-infected guigna, which had haemorrhagic diarrhoea and died a few days after arrival at a wildlife rescue centre. Our findings reveal widespread presence of Carnivore protoparvovirus-1 across the guigna distribution in Chile and suggest that virus transmission potentially occurs from domestic to wild carnivores, causing severe disease and death in susceptible wild guignas
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