1,577 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
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 post-contrast images acquired at 2min ± 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 node-specific 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 cance
"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''
Ecología y comportamiento reproductivo de Eleutherodactylus aureolineatus (Anura, Brachycephalidae) del dosel de la cuenca del Amazonas Superior, Ecuador
Exploration and investigation of the anuran fauna in the canopies of the Upper Amazon Basin has led to the recent discoveries of new species of the genus Eleutherodactylus utilizing the microhabitat within bromeliads. Detailed information on the ecology and natural history of these communities are scarce due, in part, to the difficulty of accessing their habitat. New sampling methods for rainforest canopies have allowed for the collection and observation of the herpetofauna utilizing this habitat. Sexual size dimorphism in Eleutherodactylus aureolineatus, confirms placement in the E. unistrigatus species group and E. lacrimosus assemblage. The described microhabitat, vocalization characteristics, reproductive behavior and egg deposition of E. aureolineatus provides significant ecological background on this poorly documented group of frogs and their important "wetlands in the sky". The data and observations herein contribute to the overall understanding of the characters and ecological factors which define the E. lacrimosus assemblage.La exploración y la investigación de la fauna de anuros en el estrato del dosel de la cuenca del Amazonas Superior ha llevado a descubrimientos recientes de nuevas especies del genero Eleutherodactylus que utilizan el interior de las bromelidas como micro-hábitat. La información detallada en la ecología y la historia natural de estas comunidades es escasa debido en parte a la dificultad de acceso de su hábitat. Nuevos métodos de muestreo para doseles de selvas pluviales han tomado en cuenta la colecta y la observación de la herpetofauna que utiliza este hábitat. El dimorfismo sexual de tamaño en Eleutherodactylus aureolineatus confirma su posición dentro del grupo de especies de E. unistrigatus y la colección de E. lacrimosus. La descripción del micro-hábitat, características de vocalización, comportamiento reproductivo y el sitio de deposición de huevo de E. aureolineatus provee antecedentes ecológicos importantes para este grupo de ranas pobremente documentadas y sus importantes "pantanos en el cielo". Los datos y las observaciones que aquí se presentan, contribuyen a la comprensión general de los caracteres y los factores ecológicos que definen la colección de E. lacrimosus
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Cobalt and nickel uptake by silica-based extractants
The pKas of ethyl/butyl phosphonate silica (EBP-Si) have been determined, and the removal of cobalt and nickel from solution was investigated as a function of various parameters and compared with those of Purolite S950. pH uptake experiments suggested a combination of ion exchange and acid dissociation of the surface occurring. Isotherm data, fitted using the Langmuir and Dubinin–Radushkevich (D-R) models, indicated that stronger complexes formed with S950 than with EBP-Si. Kinetic data, fitted using a pseudo-second-order model, suggested that the rate-determining process is the reaction of metal ions with the chelating functionality of the resin. Uptake by EBP-Si is two to three times faster than that on S950
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