845 research outputs found
USING CALLING ACTIVITY TO PREDICT CALLING ACTIVITY: A CASE STUDY WITH THE ENDANGERED HOUSTON TOAD (BUFO [ANAXYRUS] HOUSTONENSIS)
Understanding anuran calling activity patterns is important for maximizing efficiency and value of call survey data collection and analyses. Previous studies have primarily focused on identifying and quantifying abiotic variables that influence anuran calling activity, and investigating relationships between calling activity and population estimates. In this study we investigated the use of a predictor pond approach to guide call survey effort. In this approach, calling activity at a subset of breeding sites (e.g., ponds) is used as a predictor of calling activity at additional breeding sites, with the goal being to minimize sampling effort while simultaneously maximizing sampling efficiency. We explored the efficiency of this approach using call survey data collected on the endangered Houston Toad (Bufo [Anaxyrus] houstonensis) at 15 known breeding ponds over 9 survey years. We found that if calling activity at 3 predictor ponds was used to decide if additional call surveys would occur at the remaining 12 ponds, we would have hypothetically correctly assumed calling activity was not occurring at non-predictor ponds on 92.1% of survey nights, and we would have hypothetically detected 93.9% of the total number of detected individuals over the 9 survey years. We found the predictor pond approach performed well in our case study, and believe it could be a valuable tool for many anuran monitoring programs
Encontro casual na região central do Texas fornece informações sobre a ecologia da estivação de Siren nettingi (Caudata: Sirenidae)
Siren spp. costumam ser vertebrados dominantes nas áreas úmidas que ocupam e são conhecidas por estivar quando essas áreas úmidas secam. Considerações práticas limitam as observações in situ de indivíduos em estivação. Em 12 de outubro de 2021, descobrimos por acaso um agregado em estivação de Siren nettingi no condado de Bastrop, Texas, Estados Unidos. Essas salamandras foram escavadas em solo compacto e rochoso adjacente a uma estrada de caliche, em profundidades que variavam entre ~0,2 e 1,5 m. A vegetação dominante nesse local incluía Ulmus crassifolia, Persicaria sp. e várias espécies de gramíneas. Recuperamos 140 indivíduos, dos quais sete foram resgatados e 133 foram capturados vivos. Medimos 115 deles quanto ao comprimento rostro-cloacal (SVL) e observamos que o agregado era dominado por jovens. Estimamos uma densidade de estivação de 2,33 indivíduos/m2 que é comparável às densidades estimadas para populações sem estivação. No entanto, como não houve monitoramento para esse estudo, provavelmente tenha ocorrido um evento de mortalidade em massa. Portanto, sugerimos que a construção de estradas no habitat preferido seja considerada uma ameaça às populações dessas salamandras.Siren spp. are often dominant vertebrates in the wetlands they occupy and are known to estivate when such wetlands dry up. Practical considerationslimit in-situ observations of estivating individuals. On 12 October 2021, we incidentally discovered an estivating aggregate of Siren nettingi in Bastrop County, Texas, USA. These salamanders were excavated from compact, rocky soil adjacent to a caliche road, at depths that ranged between ~0.2 to 1.5 m. The dominant vegetation at this site included Ulmus crassifolia, Persicaria sp., and various grass species. We recovered 140 individuals of which seven were salvaged and 133 were captured live. We measured 115 of these for snout–vent length (SVL) and observed the aggregate was predominated by juveniles. We estimated an estivation density of 2.33 sirens/m2 that is comparable to densities estimated for non-estivating populations. However, in-lieu of monitoring that was in place for this study, we expect a mass mortality event would have likely occurred. We therefore suggest that roadway construction in preferred habitat be considered as a threat to siren populations
A Place to Call Home: Amphibian Use of Created and Restored Wetlands
Loss and degradation of wetland habitats are major contributing factors to the global decline of amphibians. Creation and restoration of wetlands could be a valuable tool for increasing local amphibian species richness and abundance. We synthesized the peer-reviewed literature addressing amphibian use of created and restored wetlands, focusing on aquatic habitat, upland habitat, and wetland connectivity and configuration. Amphibian species richness or abundance at created and restored wetlands was either similar to or greater than reference wetlands in 89% of studies. Use of created and restored wetlands by individual species was driven by aquatic and terrestrial habitat preferences, as well as ability to disperse from source wetlands. We conclude that creating and restoring wetlands can be valuable tools for amphibian conservation. However, the ecological needs and preferences of target species must be considered to maximize the potential for successful colonization and long-term persistence
Curvature-coupling dependence of membrane protein diffusion coefficients
We consider the lateral diffusion of a protein interacting with the curvature
of the membrane. The interaction energy is minimized if the particle is at a
membrane position with a certain curvature that agrees with the spontaneous
curvature of the particle. We employ stochastic simulations that take into
account both the thermal fluctuations of the membrane and the diffusive
behavior of the particle. In this study we neglect the influence of the
particle on the membrane dynamics, thus the membrane dynamics agrees with that
of a freely fluctuating membrane. Overall, we find that this curvature-coupling
substantially enhances the diffusion coefficient. We compare the ratio of the
projected or measured diffusion coefficient and the free intramembrane
diffusion coefficient, which is a parameter of the simulations, with analytical
results that rely on several approximations. We find that the simulations
always lead to a somewhat smaller diffusion coefficient than our analytical
approach. A detailed study of the correlations of the forces acting on the
particle indicates that the diffusing inclusion tries to follow favorable
positions on the membrane, such that forces along the trajectory are on average
smaller than they would be for random particle positions.Comment: 16 pages, 8 figure
Staging of endometrial cancer with MRI: guidelines of the european society of urogenital imaging
The purpose of this study
was to define guidelines for endometrial
cancer staging with MRI. The
technique included critical review and
expert consensus of MRI protocols by the female imaging subcommittee of
the European Society of Urogenital
Radiology, from ten European institutions,
and published literature between
1999 and 2008. The results
indicated that high field MRI should
include at least two T2-weighted
sequences in sagittal, axial oblique or
coronal oblique orientation (short and
long axis of the uterine body) of the
pelvic content. High-resolution postcontrast
images acquired at 2 min ± 30 s
after intravenous contrast injection
are suggested to be optimal for the
diagnosis of myometrial invasion. If
cervical invasion is suspected, additional
slice orientation perpendicular
to the axis of the endocervical channel
is recommended. Due to the limited
sensitivity of MRI to detect lymph
node metastasis without lymph nodespecific
contrast agents, retroperitoneal
lymph node screening with
pre-contrast sequences up to the level
of the kidneys is optional. The likelihood
of lymph node invasion and
the need for staging lymphadenectomy
are also indicated by high-grade histology
at endometrial tissue sampling
and by deep myometrial or cervical
invasion detected by MRI. In conclusion,
expert consensus and literature
review lead to an optimized MRI
protocol to stage endometrial cancer
MR and CT techniques
Magnetic resonance imaging (MRI) and computed
tomography (CT) are routinely used in
female pelvis imaging. MRI is primarily useful
for locoregional characterization of benign
and malignant diseases. CT is less accurate in
locoregional evaluation, but remains useful in
the follow-up of treated gynecological malignancies,
as well as in the setting of emergency
and in the guidance of biopsies. Although
transabdominal and transvaginal ultrasonography
(US) is not under the scope of this chapter,
it remains the first-line imaging method
for most gynecological conditions.info:eu-repo/semantics/publishedVersio
"Safe" Coulomb Excitation of 30Mg
We report on the first radioactive beam experiment performed at the recently
commissioned REX-ISOLDE facility at CERN in conjunction with the highly
efficient gamma spectrometer MINIBALL. Using 30Mg ions accelerated to an energy
of 2.25 MeV/u together with a thin nat-Ni target, Coulomb excitation of the
first excited 2+ states of the projectile and target nuclei well below the
Coulomb barrier was observed. From the measured relative de-excitation gamma
ray yields the B(E2; 0+ -> 2+) value of 30Mg was determined to be 241(31)
e2fm4. Our result is lower than values obtained at projectile fragmentation
facilities using the intermediate-energy Coulomb excitation method, and
confirms the theoretical conjecture that the neutron-rich magnesium isotope
30Mg lies still outside the ``island of inversion''
11Be(beta-p), a quasi-free neutron decay?
We have observed beta-delayed proton emission from the neutron-rich nucleus
11Be by analysing a sample collected at the ISOLDE facility at CERN with
accelerator mass spectrometry (AMS). With a branching ratio of (8.4 +- 0.6)
10^{-6} the strength of this decay mode, as measured by the B(GT)-value, is
unexpectedly high. The result is discussed within a simple single-particle
model and could be interpreted as a quasi-free decay of the 11Be halo neutron
into a single-proton state.Comment: 6 pages, 2 figure
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