242 research outputs found
A Method to Determine the In-Air Spatial Spread of Clinical Electron Beams
We propose and analyze in detail a method to measure the in-air spatial
spread parameter of clinical electron beams. Measurements are performed at the
center of the beam and below the adjustable collimators sited in asymmetrical
configuration in order to avoid the distortions due to the presence of the
applicator. The main advantage of our procedure lies in the fact that the dose
profiles are fitted by means of a function which includes, additionally to the
Gaussian step usually considered, a background which takes care of the dose
produced by different mechanisms that the Gaussian model does not account for.
As a result, the spatial spread is obtained directly from the fitting procedure
and the accuracy permits a good determination of the angular spread. The way
the analysis is done is alternative to that followed by the usual methods based
on the evaluation of the penumbra width. Besides, the spatial spread found
shows the quadratic-cubic dependence with the distance to the source predicted
by the Fermi-Eyges theory. However, the corresponding values obtained for the
scattering power are differing from those quoted by ICRU nr. 35 by a factor ~2
or larger, what requires of a more detailed investigation.Comment: 11 pages, 5 Postscript figures, to be published in Medical Physic
On the kinematics of massive star forming regions: the case of IRAS 17233-3606
Direct observations of accretion disks around high-mass young stellar objects
would help to discriminate between different models of formation of massive
stars. However, given the complexity of massive star forming regions, such
studies are still limited in number. Additionally, there is still no general
consensus on the molecular tracers to be used for such investigations. Because
of its close distance and high luminosity, IRAS 17233-3606 is a potential good
laboratory to search for traces of rotation in the inner gas around the
protostar(s). Therefore, we selected the source for a detailed analysis of its
molecular emission at 230 GHz with the SMA. We systematically investigated the
velocity fields of transitions in the SMA spectra which are not affected by
overlap with other transitions, and searched for coherent velocity gradients to
compare them to the distribution of outflows in the region. Beside CO emission
we also used high-angular H2 images to trace the outflow motions driven by the
IRAS 17233-3606 cluster. We find linear velocity gradients in many transitions
of the same molecular species and in several molecules. We report the first
detection of HNCO in molecular outflows from massive YSOs. We discuss the CH3CN
velocity gradient taking into account various scenarios: rotation, presence of
multiple unresolved sources with different velocities, and outflow(s). Although
other interpretations cannot be ruled out, we propose that the CH3CN emission
might be affected by the outflows of the region. Higher angular observations
are needed to discriminate between the different scenarios. The present
observations, with the possible association of CH3CN with outflows in a few
thousands AU around the YSOs' cluster, (i) question the choice of the tracer to
probe rotating structures, and (ii) show the importance of the use of H2 images
for detailed studies of kinematics.Comment: accepted for publication in A&
Protocol to characterize immune cell subpopulations in cerebrospinal fluid of patients with neuroinflammatory diseases using mass cytometry
Phenotypic and compositional changes of immune cells in cerebrospinal fluid (CSF) can be used as biomarkers to help diagnose and track disease activity for neuroinflammatory and neurodegenerative diseases. Here, we present a workflow to perform high-dimensional immune profiling at single-cell resolution using cytometry by time-of-flight (CyTOF) on cells isolated from the CSF of patients with neuroinflammation. We describe steps for sample collection and preparation, barcoding to allow for multiplexing, and downstream data analysis using R. For complete details on the use and execution of this protocol, please refer to Fernández-Zapata et al
Searching long-lasting phosphor at 385 nm
Synthesis and characterization of UV emmiting phospor for application in photocatalytic degradation of contaminants
CUCARACHAS: BIOLOGÍA E IMPORTANCIA EN SALUD PÚBLICA
Las cucarachas pertenecen a uno de los grupos de insectos mejor conocidos y más antiguos; los organismos pertenecientes a este grupo, tienen la característica de adaptarse a una gran variedad de hábitat. Presentan una gran variedad de formas, tamaños, colores y hábitat en los que subsisten, siendo solo unas cuantas las que representan importancia en salud pública; en la actualidad se conocen alrededor de 45 patógenos que pueden transmitir de manera mecánica y natural, principalmente bacterias, hongos protozoarios, helmintos y virus. Mostrándolos como un riesgo para salud pública en las colectividades humanas.Palabras claves: cucarachas, vectores, salud pública cockrach, vector, public healt
MODO DE ACCIÓN DE LOS INSECTICIDAS
La generalidad de los insecticidas actúa en algunos organismos y todos se inmiscuyen en LA interrupción de determinadas transformaciones metabólicas; pero es complejo establecer el modo de acción y en algunas casos no se conoce, ya que algunos insecticidas muestran más de un modo de acción, lo que dificulta su clasificación.En este caso nos encaminaremos a exponer los diferentes maneras de acción de los cuatro grupos más importantes de insecticidas conocidos como son los organoclorados, organofosforados, carbamatos y piretroides.Palabras claves: insecticidas, organoclorados, organofosforados, carbamatos y piretroidesinsecticide, organochlorinated, organophosphorated, carbamates, piretroid
Predation impact on threatened spur-thighed tortoises by golden eagles when main prey is scarce
A reduction in adult survival in long-living species may compromise population growth rates. The spur-thighed tortoise (Testudo graeca) is a long-lived reptile that is threatened by habitat loss and fragmentation. Golden eagles (Aquila chrysaetos), whose breeding habitats overlap that of tortoises, may predate them by dropping them onto rocks and breaking their carapaces. In SE Spain, the number of golden eagles has increased in the last decades and the abundance of their main prey (i.e., rabbits Oryctolagus cuniculus) has decreased. Our aims were to 1) describe the role of tortoises in golden eagles’ diet, and 2) estimate the predation impact of golden eagles on tortoises in eagles’ territories and in the regional tortoise population. We collected regurgitated pellets and prey remains under eagle nests and roosts, and obtained information on tortoise abundance and population structure and rabbit abundance. We found that tortoises were an alternative prey to rabbits, so that eagles shifted to the former where the latter were scarce. The average predation rate on tortoises was very low at the two studied scales. However, eagles showed a marked selection for adult female tortoises, which led the tortoise sex ratio to be biased towards males in those eagle territories with higher tortoise predation. Whether this may compromise the spur-thighed tortoise long-term population viability locally deserves further attention.Much information on the spur-thighed tortoise populations and the regional abundance model was obtained with Projects CGL2012-33536 and CGL2015-64144 funded by the Spanish Ministry of Science and the European Regional Development Fund, Grant PID2019-105682RA-I00, funded by MCIN/AEI/10.13039/501100011033 and AICO/2021/145 funded by the Regional Valencian Government. MM was supported by a Ramón y Cajal research contract from MINECO (RYC-2015-19231), MCM by a pre-doctoral grant of the Spanish Ministry of Science (FPU1700633), and RCRC by a postdoctoral grant funded by the Regional Valencian Government (APOSTD/2020/090) and by the European Union-Next Generation EU in the Maria Zambrano Program (ZAMBRANO 21-26). The Dirección General de Gestión del Medio Natural of Andalusian Government (SGB/FOA/AFR) and the Dirección General de Medio Natural of the Murcia Region authorised and facilitated the sampling of golden eagle territories (AUF20140061) and the spur-thighed tortoise populations (SGYB/AF/DBP, SGYB/AFR/DBP, AUF20160056, AUF20140057)
Amalophyllon miraculum (Gesneriaceae), an exceptionally small lithophilous new species from the western Andean slopes of Ecuador
Recent exploratory field expeditions to the western slopes of the Ecuadorian Andes resulted in the discovery of a new species of Amalophyllon (Gesneriaceae). Amalophyllon miraculum J.L.Clark, sp. nov. is described from two localities in the Centinela region in the Santo Domingo de los Tsáchilas province. The new species is differentiated from congeners by the pendent habit, basal rosette of leaves, leaf blades with deeply serrate margins, and miniature size. Based on IUCN guidelines, a preliminary conservation status is assigned as Critically Endangered (CR)
From local monitoring to a broad‐scale viability assessment: a case study for the Bonelli's Eagle in western Europe
Population viability analysis (PVA) has become a basic tool of current conservation practice. However, if not accounted for properly, the uncertainties inherent to PVA predictions can decrease the reliability of this type of analysis. In the present study, we performed a PVA of the whole western European population (France, Portugal, and Spain) of the endangered Bonelli's Eagle (Aquila fasciata), in which we thoroughly explored the consequences of uncertainty in population processes and parameters on PVA predictions. First, we estimated key vital rates (survival, fertility, recruitment, and dispersal rates) using monitoring, ringing, and bibliographic data from the period 1990-2009 from 12 populations found throughout the studied geographic range. Second, we evaluated the uncertainty about model structure (i.e., the assumed processes that govern individual fates and population dynamics) by comparing the observed growth rates of the studied populations with model predictions for the same period. Third, using the model structures suggested in the previous step, we assessed the viability of both the local populations and the overall population. Finally, we analyzed the effects of model and parameter uncertainty on PVA predictions. Our results strongly support the idea that all local populations in western Europe belong to a single, spatially structured population operating as a source-sink system, whereby the populations in the south of the Iberian Peninsula act as sources and, thanks to dispersal, sustain all other local populations, which would otherwise decline. Predictions regarding population dynamics varied considerably, and models assuming more constrained dispersal predicted more pessimistic population trends than models assuming greater dispersal. Model predictions accounting for parameter uncertainty revealed a marked increase in the risk of population declines over the next 50 years. Sensitivity analyses indicated that adult and pre‐adult survival are the chief vital rates regulating these populations, and thus, the conservation efforts aimed at improving these survival rates should be strengthened in order to guarantee the long‐term viability of the European populations of this endangered species. Overall, the study provides a framework for the implementation of multi‐site PVAs and highlights the importance of dispersal processes in shaping the population dynamics of long‐lived birds distributed across heterogeneous landscapes
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