3,311 research outputs found
Activity Level-Predation Risk Tradeoff in a Tadpole Guild: Implications for Community Organization Along the Hydroperiod Gradient
Increasing activity levels permit greater food intake for use towards growth and reproduction, consequently increasing predation risk via increased detection. Larval anurans are models to examine activity level-predation risk tradeoffs, as they occupy a variety of lentic habitats that impose constraints on the distribution and abundance of species. Ephemeral ponds have a low abundance and diversity of predators and as a result tadpole species tend to have high foraging rates for rapid development. Permanent ponds generally possess a greater diversity and abundance of predators and tadpoles inhabiting these locations tend to have low activity rates or chemical defenses to minimize predation risk. The objective of this research was to examine how interspecific variation in activity level and response to predation risk, corresponds to the distributions of tadpole species along the hydroperiod gradient. Furthermore, we examined the intraspecific variation in activity level among the species. We conducted a series of laboratory experiments in which we quantified baseline activity patterns and the change in activity after the addition of a predator or exposure to alarm cues, for 12 species of larval anurans native to East Texas. Species that maintained a high activity level generally occupied ephemeral ponds and species that maintained low activity levels generally occupied permanent ponds. Only one species (Gastrophryne carolinensis) decreased their activity level in the presence of predator cues or conspecific alarm cues. These results highlight this tradeoff can have consequences on the life histories of multiple species, providing insight into how it affects the organization of ecological communities
Influence of a tight isotropic harmonic trap on photoassociation in ultracold homonuclear alkali gases
The influence of a tight isotropic harmonic trap on photoassociation of two
ultracold alkali atoms forming a homonuclear diatomic is investigated using
realistic atomic interaction potentials. Confinement of the initial atom pair
due to the trap leads to a uniform strong enhancement of the photoassociation
rate to most, but also to a strongly suppressed rate for some final states.
Thus tighter traps do not necessarily enhance the photoassociation rate. A
further massive enhancement of the rate is found for strong interatomic
interaction potentials. The details of this interaction play a minor role,
except for large repulsive interactions for which a sharp window occurs in the
photoassociation spectrum as is known from the trap-free case. A comparison
with simplified models describing the atomic interaction like the
pseudopotential approximation shows that they often provide reasonable
estimates for the trap-induced enhancement of the photoassociation rate even if
the predicted rates can be completely erroneous.Comment: 19 pages, 17 figure
A Qualitative Descriptive Study of Teacher and Administrator Perceptions of Professional Learning Communities in a Texas School District With a Predominance of Hispanic Staff and Students
The purpose of conducting this qualitative descriptive study on professional learning communities in a South Texas public school district was to see if they are meaningful and structured to support the improvement of student success in the classroom as well as providing the support and steps outlined in an effective professional learning community. The study focused on the skill level implemented by the teachers, administrators, and other members of the committee to communicate, access the personal skills to collaborate with peers, and utilize the data for student achievement. This study sought to gain and understand the perceptions of department heads, administrators, and educators of how professional learning communities’ elements, characteristics, and three big ideas that guide a team when collaborating in a large district. Qualitative data were from 12 staff members of a large district in South Texas comprised of Hispanic administrators, Hispanic department heads, and Hispanic core subject coordinators. Open-ended interviews composed of 19 questions assemble the data. The findings of this study confirmed the perceptions in which participants felt supported and prepared for how professional learning communities supported the improvement of student success in the classroom. It also indicated where they felt a lack of support during how professional learning communities, improvement, and discussion is needed to achieve a desirable outcome. The results of this study balance other past research on the importance of how professional learning communities improve students’ scores and success. Keywords: professional learning community, collaboration, continuous improvement, student achievement, student learnin
Theoretical description of two ultracold atoms in finite 3D optical lattices using realistic interatomic interaction potentials
A theoretical approach is described for an exact numerical treatment of a
pair of ultracold atoms interacting via a central potential that are trapped in
a finite three-dimensional optical lattice. The coupling of center-of-mass and
relative-motion coordinates is treated using an exact diagonalization
(configuration-interaction) approach. The orthorhombic symmetry of an optical
lattice with three different but orthogonal lattice vectors is explicitly
considered as is the Fermionic or Bosonic symmetry in the case of
indistinguishable particles.Comment: 19 pages, 5 figure
Low-Grade Appendiceal Mucinous Neoplasm Involving the Endometrium and Presenting with Mucinous Vaginal Discharge.
Primary appendiceal mucinous lesions are uncommon and represent a spectrum from nonneoplastic mucous retention cysts to invasive adenocarcinoma. Low-grade appendiceal mucinous neoplasms (LAMNs) represent an intermediate category on this spectrum and can be classified according to whether or not they are confined to the appendix. Although LAMNs are frequently confined to the appendix, they can also spread to the peritoneum and clinically progress as pseudomyxoma peritonei (i.e., mucinous ascites). Thus, the appropriate classification of appendiceal primary neoplasia is essential for prognosis and influences clinical management. In addition, the precise classification, management, and clinical outcome of patients with disseminated peritoneal disease remain controversial. Here, we report an unusual case of LAMN with pseudomyxoma peritonei that initially presented with mucinous and bloody vaginal discharge. Pathological evaluation revealed low-grade appendiceal mucinous neoplasm with secondary involvement of the peritoneum, ovaries, and endometrial surface. Therefore, LAMN should be considered in the differential diagnosis of mucinous vaginal discharge
Photoassociative spectroscopy at long range in ultracold strontium
We report photoassociative spectroscopy of Sr in a magneto-optical
trap operating on the intercombination line at 689 nm.
Photoassociative transitions are driven with a laser red-detuned by 600-2400
MHz from the atomic resonance at 461 nm. Photoassociation
takes place at extremely large internuclear separation, and the
photoassociative spectrum is strongly affected by relativistic retardation. A
fit of the transition frequencies determines the atomic lifetime
( ns) and resolves a discrepancy between experiment and
recent theoretical calculations.Comment: 4 pages, 4 figures, submitte
NucleotomĂa Percutánea Automatizada: nuestra Experiencia
Ante las diferentes tĂ©cnicas quirĂşrgicas en la patologĂa del disco lumbar, los
autores presentan su experiencia personal con la nucleotomĂa percutánea automatizada utilizando
el nucleotomo de Surgical Dynamics. Sobre un total de 50 pacientes intervenidos se
expone la técnica utilizada, con algunas variantes sobre la inicial de Onik, tal como la posición
en sedestaciĂłn del enfermo.
Se puntualizan las indicaciones y contraindicaciones y se analizan los resultados obtenidos
tras un mĂnimo de 6 meses de seguimiento.
Se considera como una técnica útil, adecuada, relativamente inócua y que no sustituye sino
que complementa a los procedimientos quirúrgicos convencionales.Faced with the different surgical techniques of lumbar disk pathology»
the authors convery personal experience with automated percutaneous nucleotomy
using the Surgical Dynamics. Based on the intervention of 50 patients, the
technique used is explained, with some variations of the Onik procedure, such as
the sitting position of the patient.
The indications and contraindications are reviewed by the analysis. The results
obtained with 6 months of follow up.
The technique is considered usefull, proper, and relatively innocuous. It does not
substitute but complements conventional surgical procedures
- …