901 research outputs found
Hábitos alimentarios de dos poblaciones de la lagartija vivípara Sceloporus minor (Squamata: Phrynosomatidae) del municipio de Guadalcázar, San Luis Potosí, México
“Los resultados de los hábitos alimentarios de S. minor indican que se comporta como un depredador generalista, ya que presentó altos valores de diversidad trófica. Esto puede deberse a que presentan una relación directa entre las presas disponibles en el ambiente durante la estación de lluvias y la frecuencia de presas encontradas en el tracto digestivo, ya que como lo reporta Tatanka y Tatanka (1982) la abundancia de artrópodos incrementa en la temporada de lluvias, principalmente himenópteros, coleópteros, ortópteros y hemípteros, coincidiendo con los valores obtenidos para S. minor que indican una preferencia por el consumo de artrópodos de la clase Insecta, siendo los grupos más importantes Hymenoptera (Formicidae), Coleoptera y Hemiptera, mientras que el resto de las categorías registradas sólo fueron consumidas de manera esporádica. El alto consumo de Hymenoptera, Coleoptera y Hemiptera es debido posiblemente a que son las presas más abundantes, además es probable que influya el valor nutricional propio de cada grupo, pues las hormigas y coleópteros contienen altos índices proteicos, ya que las primeras están constituidas del 13 al 77% de proteína, mientras que los coleópteros constituyen del 22 al 66% (Hernández et al., 2009; Leyte-Manrique y Ramírez-Bautista, 2010; Xiaoming et al., 2010)”
Ceramic sonotrodes for light alloy melt treatment
Alloy melt treatment by ultrasonic vibration is a physical processing technique that has been gathering the support of the scientific community. The use of metallic sonotrodes for this purpose has been proven very efficient; however, it promotes melt inclusion by sonotrode erosion. Such an issue is being addressed by the use of ceramic sonotrodes in low-amplitude resonance. Given that these novel sonotrodes generally have complex shapes and low displacements, this study shows an innovative approach for their characterization. Based on scanning laser Doppler vibrometry, the signal processing Python-based script was used to map the overall resonant behavior of a tubular SiAlON sonotrode, and this route is able to characterize the complex shapes in low-amplitude and high-frequency radial resonance in resonant ceramic sonotrodes. Velocity time-domain profiles are shown to be dependent on the position, and even though the radial natural frequencies of ceramic sonotrodes have low amplitudes, they are proposed as an efficient tool for melt treatment. While characterizing the radial natural mode in ceramic sonotrodes, this study proves that their low-amplitude Lamb waves are responsible for the refinement of a-grains and secondary phases in light alloys.This work was supported by PTDC/EMEEME/30967/
2017 and NORTE-0145-FEDER-030967, co-financed
by the European Regional Development Fund (ERDF),
through the Operational Programme for Competitive ness and Internationalization (COMPETE 2020), under
Portugal 2020, and by the Fundação para a Cência e a
Tecnologia – FCT I.P. national funds. Also, this work
was supported by Portuguese FCT, under the reference
project UIDB/04436/2020, and Stimulus of Scientific
Employment Application CEECIND/03991/2017
QSO 2237+0305 VR light curves from Gravitational Lenses International Time Project optical monitoring
We present VR observations of QSO 2237+0305 conducted by the GLITP
collaboration from 1999 October 1 to 2000 February 3. The observations were
made with the 2.56 m Nordic Optical Telescope at Roque de los Muchachos
Observatory, La Palma (Spain). The PSF fitting method and an adapted version of
the ISIS subtraction method have been used to derive the VR light curves of the
four components (A-D) of the quasar. The mean errors range in the intervals
0.01-0.04 mag (PSF fitting) and 0.01-0.02 mag (ISIS subtraction), with the
faintest component (D) having the largest uncertainties. We address the
relatively good agreement between the A-D light curves derived using different
filters, photometric techniques, and telescopes. The new VR light curves of
component A extend the time coverage of a high magnification microlensing peak,
which was discovered by the OGLE team.Comment: 15 pages, 3 figures, ApJ accepted (Feb 19
Effect of grain and secondary phase morphologies in the mechanical and damping behavior of Al7075 alloys
The present study evaluates the role of the microstructure in the static and dynamic mechanical behavior of as-cast Al7075 alloy promoted by ultrasonic treatment (US) during solidification. The characterization of samples revealed that US treatment promoted grain and intermetallics refinement, changed the shape of the intermetallic phases (equilibrium phases of soluble M and/or T (Al, Cu, Mg, Zn) and their insoluble Al-Cu-Fe compounds) and lead to their uniform distribution along the grain boundaries. Consequently, the mechanical properties and damping capacity above critical strain values were enhanced by comparison with values obtained for castings produced without US vibration. This results suggest that the grain and secondary phases refinement by US can be a promising solution to process materials to obtain high damping and high strength characteristics.This research was supported by FEDER/COMPETE funds and by national funds through FCT - Portuguese Foundation for Science and Technology and was developed on the aim of the research Post-Doctoral grant SFRH/BPD/76680/2011. Also, this work has been supported by the FCT in the scope of the project: UID/EEA/04436/2013.info:eu-repo/semantics/publishedVersio
Gender Justice In The Americas: A Transnational Dialogue On Sexuality, Violence, Reproduction, And Human Rights
Gender Justice In The Americas: A Transnational Dialogue On Sexuality, Violence, Reproduction, And Human Rights
Different Evolutionary Stages in the Massive Star Forming Region S255 Complex
To understand evolutionary and environmental effects during the formation of
high-mass stars, we observed three regions of massive star formation at
different evolutionary stages that reside in the same natal molecular cloud.
Methods. The three regions S255IR, S255N and S255S were observed at 1.3 mm with
the Submillimeter Array (SMA) and followup short spacing information was
obtained with the IRAM 30m telescope. Near infrared (NIR) H + K-band spectra
and continuum observations were taken for S255IR with VLT-SINFONI to study the
different stellar populations in this region. The combination of millimeter
(mm) and near infrared data allow us to characterize different stellar
populations within the young forming cluster in detail. While we find multiple
mm continuum sources toward all regions, their outflow, disk and chemical
properties vary considerably. The most evolved source S255IR exhibits a
collimated bipolar outflow visible in CO and H2 emission, the outflows from the
youngest region S255S are still small and rather confined in the regions of the
mm continuum peaks. Also the chemistry toward S255IR is most evolved exhibiting
strong emission from complex molecules, while much fewer molecular lines are
detected in S255N, and in S255S we detect only CO isotopologues and SO lines.
Also, rotational structures are found toward S255N and S255IR. Furthermore, a
comparison of the NIR SINFONI and mm data from S255IR clearly reveal two
different (proto) stellar populations with an estimated age difference of
approximately 1 Myr. A multi-wavelength spectroscopy and mapping study reveals
different evolutionary phases of the star formation regions. We propose the
triggered outside-in collapse star formation scenario for the bigger picture
and the fragmentation scenario for S255IR.Comment: 23 pages,25 figures, accepted by A&
Genomewide Analysis of Aryl Hydrocarbon Receptor Binding Targets Reveals an Extensive Array of Gene Clusters that Control Morphogenetic and Developmental Programs
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