4,817 research outputs found
Pollen quality, meiotic abnormalities and poliploidy inSisyrinchium commutatum (Iridaceae)
O comportamento meiótico de Sisyrinchium commutatum (Iridaceae) foi avaliado e associado com as altas taxas de inviabilidae polínica observada em uma população do sudeste do Brasil. Além disso, pela primeira vez, descreve-se o número cromossômico desta espécie, contribuindo assim para a sistemática do grupo. Alguns aspectos da biologia floral são relatados , como a ocorrência de apresentação secundária de pólen e a ausência de autopolinização espontânea e apomixia para esta espécie. Os resultados do presente trabalho confirmam a ação das anormalidades meióticas como possível mecanismo disruptivo na formação de grãos-de-pólen com consequências ao sucesso reprodutivo na população estudada .The meiotic behaviour of Sisyrinchium commutatum (Iridaceae) was studied and associated to the pollen quality observed in a southeastern population in Brazil. For the first time, the chromosome number is reported for this species (2n = 36). Some traits of floral biology were recorded and secondary pollen presentation as well as the absence of autonomous self-fertilization and apomixy were observed. The results of this study confirm the abnormalities in the meiosis process breaking the pollen grain formation with consequences to reproductive success in the studied population.Fil: Avila Jr., Rubem Samuel de. Universidade Federal do Pampa; BrasilFil: Urdampilleta, Juan Domingo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Gil, A. S. Bragança. Museu Paraense Emílio Goeldi; Argentin
Exploring Counselor Educator Dispositions Related to Teaching
This study explores students’ preferences for counselor educator (CE) teaching dispositions. Forty-eight counselor education students completed a Q sort and answered post-sort qualitative questions. The study found four types of student preferences: a focus on experiential teaching, a focus on content and affect orientation, a focus on the educator-student relationship, and a focus on developing clinical skills. Also among the findings are a set of items that were unanimously unimportant to the participants: CE engagement in research and gatekeeping. These preferences are situated within the scholarship of teaching and learning and evidence-based practices in counselor education. Practical and research implications are shared
The protoMIRAX Hard X-ray Imaging Balloon Experiment
The protoMIRAX hard X-ray imaging telescope is a balloon-borne experiment
developed as a pathfinder for the MIRAX satellite mission. The experiment
consists essentially in a coded-aperture hard X-ray (30-200 keV) imager with a
square array (1313) of 2mm-thick planar CZT detectors with a total area
of 169 cm. The total, fully-coded field-of-view is and the angular resolution is 143'. In this paper we
describe the protoMIRAX instrument and all the subsystems of its balloon
gondola, and we show simulated results of the instrument performance. The main
objective of protoMIRAX is to carry out imaging spectroscopy of selected bright
sources to demonstrate the performance of a prototype of the MIRAX hard X-ray
imager. Detailed background and imaging simulations have been performed for
protoMIRAX balloon flights. The 3 sensitivity for the 30-200 keV range
is ~1.9 10 photons cm s for an integration time
of 8 hs at an atmospheric depth of 2.7 g cm and an average zenith angle
of 30. We have developed an attitude control system for the balloon
gondola and new data handling and ground systems that also include prototypes
for the MIRAX satellite. We present the results of Monte Carlo simulations of
the camera response at balloon altitudes, showing the expected background level
and the detailed sensitivity of protoMIRAX. We also present the results of
imaging simulations of the Crab region. The results show that protoMIRAX is
capable of making spectral and imaging observations of bright hard X-ray source
fields. Furthermore, the balloon observations will carry out very important
tests and demonstrations of MIRAX hardware and software in a near space
environment.Comment: 9 pages, 13 figures, accepted for publication in Astronomy &
Astrophysic
Visualizing the Effect of an Electrostatic Gate with Angle-Resolved Photoemission Spectroscopy
Electrostatic gating is pervasive in materials science, yet its effects on
the electronic band structure of materials has never been revealed directly by
angle-resolved photoemission spectroscopy (ARPES), the technique of choice to
non-invasively probe the electronic band structure of a material. By means of a
state-of-the-art ARPES setup with sub-micron spatial resolution, we have
investigated a heterostructure composed of Bernal-stacked bilayer graphene
(BLG) on hexagonal boron nitride and deposited on a graphite flake. By voltage
biasing the latter, the electric field effect is directly visualized on the
valence band as well as on the carbon 1s core level of BLG. The band gap
opening of BLG submitted to a transverse electric field is discussed and the
importance of intralayer screening is put forward. Our results pave the way for
new studies that will use momentum-resolved electronic structure information to
gain insight on the physics of materials submitted to the electric field
effect
The Role of Clinical Supervision in Treating Clients with Antisocial Personality Disorder
Clinicians often have negative attitudes toward clients diagnosed with antisocial personality disorder (ASPD), which can sabotage treatment and lead to clinician burnout and job dissatisfaction. Researchers recommend clinicians receive regular clinical supervision; however, clinical supervision strategies and models related to working with ASPD are lacking. We identify supervisors’ primary task as exploring and improving clinicians’ attitudes toward clients having ASPD and examine this task within the discrimination model of clinical supervision. A case study is offered as an illustration for how to approach working with ASPD in supervision
Quaternary range and demographic expansion of Liolaemus darwinii (Squamata: Liolaemidae) in the Monte Desert of Central Argentina using Bayesian phylogeography and ecological niche modelling
Until recently, most phylogeographic approaches have been unable to distinguís between demographic and range expansion processes, making it difficult to test for the possibility of range expansion without population growth and vice versa. In this study, we applied a Bayesian phylogeographic approach to reconstruct both demographic and range expansion in the lizard Liolaemus darwinii of the Monte Desert in Central Argentina, during the Late Quaternary. Based on analysis of 14 anonymous nuclear loci and the cytochrome b mitochondrial DNA gene, we detected signals of demographic expansion starting at ~55 ka based on Bayesian Skyline and Skyride Plots. In contrast, Bayesian relaxed models of spatial diffusion suggested that range expansion occurred only between ~95 and 55 ka, and more recently, diffusion rates were very low during demographic expansion. The possibility of population growth without substantial range expansion could account for the shared patterns of demographic expansion during the Last Glacial Maxima (OIS 2 and 4) in fish, small mammals and other lizards of the Monte Desert. We found substantial variation in diffusion rates over time, and very high rates during the range expansion phase, consistent with a rapidly advancing expansion front towards the southeast shown by palaeo-distribution models. Furthermore, the estimated diffusion rates are congruent with observed dispersal rates of lizards in field conditions and therefore provide additional confidence to the temporal scale of inferred phylogeographic patterns. Our study highlights how the integration of phylogeography with palaeo-distribution models can shed light on both demographic and range expansion processes and their potential causes.Fil: Camargo Bentaberry, Arley. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Werneck, Fernanda P.. Brigham Young University. Life Science Museum. Department of Biology & Bean; Estados Unidos. Universidade de Brasılia. Departamento de Zoologia; BrasilFil: Morando, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Sites Jr., Jack W.. Brigham Young University. Life Science Museum. Department of Biology & Bean; Estados UnidosFil: Avila, Luciano Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentin
U-Pb zircon in situ dating with LA-MC-ICP-MS using a mixed detector configuration
The LA-MC-ICP-MS method applied to U-Pb in situ dating is still rapidly evolving due to improvements in both lasers and ICP-MS. To test the validity and reproducibility of the method, 5 different zircon samples, including the standard Temora-2, ranging in age between 2.2 Ga and 246 Ma, were dated using both LAMC- ICP-MS and SHRIMP. The selected zircons were dated by SHRIMP and, after gentle polishing, the laser spot was driven to the same site or on the same zircon phase with a 213 nm laser microprobe coupled to a multi-collector mixed system. The data were collected with a routine spot size of 25 μm and, in some cases, of 15 and 40 μm. A careful cross-calibration using a diluted U-Th-Pb solution to calculate the Faraday reading to counting rate conversion factors and the highly suitable GJ-1 standard zircon for external calibrations were of paramount importance for obtaining reliable results. All age results were concordant within the experimental errors. The assigned age errors using the LA-MC-ICP-MS technique were, in most cases, higher than those obtained by SHRIMP, but if we are not faced with a high resolution stratigraphy, the laser technique has certain advantages
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