The potato yellow vein disease, caused by the potato yellow vein virus (PYVV), is a limiting potato disease in northern South America. The virus can be transmitted either by the greenhouse whitefly ...(GWF),
(Westwood) (Hemiptera: Aleyrodidae), or through vegetative propagules, such as infected tubers. Recently, GWF populations have been spotlighted as one of the main drivers of PYVV re-emergence, and consequently, PYVV management has been predominantly directed toward vector control, which is heavily based on insecticide use. However, the drivers of the PYVV outbreaks as well as the contribution of GWF populations on the spread of PYVV among potato crops are still not completely understood. This study aims to assess the role of the GWF as a driver of the PYVV epidemic in the potato-producing areas in Colombia, one of the countries more severely affected by the PYVV epidemic, and whose geography allows the study of the spatial association between the vector and the disease epidemic across a wide altitude range. The geographical clusters where the PYVV epidemic is concentrated, as well as those of farms affected by the GWF were identified using a novel spatial epidemiology approach. The influence of altitude range on the association between PYVV and
was also assessed. We found a relatively poor spatial association between PYVV epidemic and the presence of the GWF, especially at altitudes above 3,000 m above mean sea level. Furthermore, GWF populations could only explain a small fraction of the extent of the PYVV epidemic in Colombia. Movement of infected seed tubers might be the main mechanism of dispersion, and could be a key driver for the PYVV infection among potato crops. Agricultural policies focused on improving quality of seed tubers and their appropriate distribution could be the most efficient control intervention against PYVV dispersion.
Resumen
La rentabilidad es uno de los factores que más influye en la selección de presas. Este factor varía en función del tamaño de la presa y del tiempo de manipulación. Por lo tanto, generalmente ...las presas grandes son altamente rentables para los consumidores e intensifican la competencia. El cleptoparasitismo es una forma de competencia en la que un individuo roba alimento previamente obtenido por otro individuo. En consecuencia, la manipulación de presas grandes debería aumentar la probabilidad de ocurrencia de cleptoparasitismo, sin embargo, estas relaciones siguen siendo poco conocidas. En este trabajo estudiamos la ocurrencia de cleptoparasitismo de la Gaviota Cáhuil (Chroicocephalus maculipennis – Laridae) sobre Zarapitos (Numenius phaeopus hudsonicus – Scolopacidae) que se alimentan de chanchitos de mar (Emerita analoga) en una playa arenosa expuesta al oleaje en el sur de Chile. Los modelos lineales generalizados, ajustados a los datos de video secuencias focales‐individuales, mostraron que la probabilidad de cleptoparasitismo tuvo una respuesta sigmoidal positiva al tiempo de manipulación. Además, con un aumento de un segundo en el tiempo de manipulación, los Zarapitos duplicaron su probabilidad de ser cleptoparasitados. Además, la probabilidad de ser cleptoparasitado fue un 17% más alta con un aumento de 10 mm en la longitud de la presa y un 47% más alta con un aumento de una gaviota por hospedador. Sin embargo, el efecto del tiempo de manipulación sobre la probabilidad de cleptoparasitismo disminuyó ligeramente (2%) con un aumento de 10 mm en la clase de tamaño de la presa. Nuestros resultados sugieren la existencia de un umbral de tiempo en el que los consumidores pueden manipular a sus presas antes de que la probabilidad de cleptoparasitismo sea demasiado alta. Sin embargo, la tasa media de ingesta de los zarapitos alcanzó 0,15 ± 0,13 kJ s−1, permitiendo que los zarapitos cumplan, en teoría, con sus requerimientos energéticos a pesar de perder algunas presas a causa de los cleptoparásitos. Este estudio proporciona una nueva visión sobre una forma común de competencia entre consumidores, destacando la importancia del tiempo de manipulación de presas para las aves playeras con un tiempo de alimentación restringido a causa de los ciclos de marea.
We estimate the molecular mass around CTA 1 using data from Planck and the Harvard CO survey. We observe that the molecular mass in the vicinity of the complex is not enough to explain the TeV ...emission observed by VERITAS, even under favorable assumptions for the cosmic ray acceleration properties of the supernova remnant. This supports the idea that the TeV emission comes from the pulsar wind nebula (PWN). Here, we model the spectrum of the PWN at possible different stages of its evolution, including both the dynamics of the PWN and the supernova remnant and their interaction via the reverse shock. We have included in the model the energy lost via radiation by particles and the particles escape when computing the pressure produced by the gas. This leads to an evolving energy partition, since for the same instantaneous sharing of the injection of energy provided by the rotational power, the field and the particles are affected differently by radiation and losses. We present the model, and study in detail how the spectrum of a canonical isolated PWN is affected during compression and re-expansion and how this may impact on the CTA 1 case. By exploring the phase-space of parameters that lead to radii in agreement with those observed, we then analyse different situations that might represent the current stage of the CTA 1 PWN, and discuss caveats and requirements of each one.
Abstract
The period and the period derivative of a pulsar are critical magnitudes for defining the properties of the magnetospheric size and plasma dynamics. The pulsar light cylinder, the magnetic ...field intensity nearby it, and the curvature radius all depend on these timing properties, and shape the observed high-energy synchro-curvature emission. Therefore, the radiative properties of pulsars are inextricably linked to them. This fact poses the question of how well does a given pulsar’s spectral energy distribution embed information of the timing parameters, and if so, whether we can deduce them if they have not been measured directly. This is relevant to possibly constrain the timing properties of potential pulsar candidates among unidentified
γ
-ray sources. We consider well-measured pulsar spectra blinding us from the knowledge of their timing properties, and address this question by using our radiative synchro-curvature model that was proven able to fit the observed spectra of the pulsar population. We find that in the majority of the cases studied (8 out of 13), the spin period is constrained within a range of about 1 order of magnitude, within which the real period lies. In the other cases, there is degeneracy and no period range can be constrained. This can be used to facilitate the blind search of pulsed signals.
Our current understanding of ultraluminous infrared galaxies suggests that they are recent galaxy mergers in which much of the gas in the former spiral disks, particularly that located at distances ...less than 5 kpc from each of the premerger nuclei, has fallen into a common center, triggering a huge starburst phenomenon. This large nuclear concentration of molecular gas has been detected by many groups, and estimates of molecular mass and density have been made. Not surprisingly, these estimates were found to be orders of magnitude larger than the corresponding values found in our Galaxy. In this paper, a self-consistent model of the high-energy emission of the superstarburst galaxy Arp 220 is presented. The model also provides an estimate of the radio emission from each of the components of the central region of the galaxy (western and eastern extreme starbursts and molecular disk). The predicted radio spectrum is found as a result of the synchrotron and free-free emission and absorption of the primary and secondary steady population of electrons and positrons. The latter is the output of charged pion decay and knock-on leptonic production, subject to a full set of losses in the interstellar medium. The resulting radio spectrum is in agreement with subarcsecond radio observations, which is what allows us to estimate the magnetic field. In addition, the FIR emission is modeled with dust emissivity, and the computed FIR photon density is used as a target for inverse Compton process as well as to give an account of losses in the gamma -ray escape. Bremsstrahlung emission and neutral pion decay are also computed, and the gamma -ray spectrum is finally predicted. Future possible observations with GLAST and the ground-based Cerenkov telescopes are discussed.
Bis(benzimidazole)amine‐based copper complexes, with structural similarities to the active sites of Lytic Polysaccharide Monooxygenase enzymes (LPMOs), were tested for the oxidative degradation of ...cellulose. Spectroscopic characterization of the complexes, as well as structural authentication of one of them, confirm a tetragonal coordination environment with 3 nitrogen donors, as well as a thioether in axial positions. Aqueous oxidative degradation of cellulose was achieved with the CuII complexes and H2O2 as oxidant through putative cupric‐hydroperoxo intermediates. Conversion of cellulose was achieved in up to 67 % yield of soluble oligosaccharide derivatives at ambient temperature and pressure. The products were analyzed in aqueous solution by HPLC‐MS, confirming oxidative depolymerization of cellulose under ambient conditions, in an analogous fashion to LPMOs.
Biomimetic chemistry: LPMO‐inspired benzimidazole‐based copper complexes oxidatively degrade cellulose to cellobiose, aldonic acid and levoglucosan as soluble products in the presence of hydrogen peroxide/triethylamine as oxidant mixture under mild conditions through initially formed cupric hydroperoxo intermediates.
Background
Serum anti‐myenteric autoantibodies define autoimmune achalasia and tissue MMP‐9 activity may locally process autoantigenic proteins in the muscle of the lower esophageal sphincter (LES) ...of achalasia patients.
Methods
Biopsies of the LES muscle from 36 achalasia patients, 6 esophagogastric junction outflow obstruction (EGJOO) patients, and 16 transplant donors (TD) were compared in a blind cross‐sectional study. Histological characteristics such as inflammation, fibrosis, presence of ganglion cells, cells of Cajal, GAD65, PNMA2, S‐100, P substance, and MMP‐9 proteoforms in tissue were assessed by H&E and Picrosirius Red staining and immunohistochemistry analysis. Anti‐neuronal antibodies, onconeural antigens, recoverin, SOX‐1, titin, zic4, GAD65, and Tr were evaluated by immunoblot/line assay.
Key Results
Tissue of achalasia patients had heterogeneous inflammatory infiltrates with fibrosis and contrasting higher levels of activated MMP‐9, as compared with EGJOO and TD. Moreover, lower ganglion cell percentages and cell of Cajal percentages were determined in esophageal tissues of achalasia patients versus TD. The tissues of achalasia versus EGJOO patients had higher GAD65 and PNMA2 protein expression. Unexpectedly, these proteins were absent in TD tissue. S‐100 and P substance had similar expression levels in tissues of achalasia patients versus TD and EGJOO. Most of the achalasia sera had anti‐GAD65 (83%) and anti‐PNMA2 (90%) autoantibodies versus EGJOO (17% and 33%, respectively) and healthy volunteers (10% and 0%, respectively).
Conclusions and Inferences
Tissue‐specific ectopic expression of GAD65 and PNMA/Ta2 and active MMP‐9, associated with the presence of specific autoantibodies directed against these proteins, might participate in the pathophysiology of achalasia triggering and/or perpetuating autoimmune disease.
Tissue‐specific ectopic expression of GAD65 and PNMA/Ta2 and active MMP‐9, associated with the presence of specific autoantibodies directed against these proteins, might participate in the pathophysiology of achalasia triggering and/or perpetuating autoimmune disease.
ABSTRACT
We apply a synchrocurvature spectral emission model based on characterizing the dynamics of magnetospheric particles to fit the phase-average spectra of the most extended data base for the ...non-thermal spectra of pulsars. We consider 36 pulsars with well-determined non-thermal spectra from X-rays to gamma-rays. The sample includes Crab and the Crab twin, for which the spectra extend even to the optical/ultraviolet and infrared energies. We find that the model – with just three physical parameters and a global scaling – can fit the observations well across eight orders of magnitude for 18 of the 36 pulsars studied. Additionally, we find a set of eight pulsars for which the model still provides arguably good fits and another set of 10 pulsars for which the model fails in reproducing the spectra. We discuss why, propose and provide physical interpretations for a simple model extension (related to the geometry of the accelerating system with regards to the observer) that allows dealing with all such cases, ultimately providing very good fits for all pulsars. The extended model is still austere, adding only two additional parameters to the former set, of the same kind of the ones previously used. We use these fits to discuss issues going from the observed spectral origin, to the extent of the dominance of synchrotron or curvature regimes, the use of a model as predictor for searching new non-thermal pulsars starting from gamma-ray surveys, and how the model offers a setting where phase shifts between X-ray and gamma-ray light curves would naturally arise.
Plant–virus interactions are affected by environmental conditions that determine plant vulnerability to pathogens and the population dynamics of insect vectors. We hypothesize that drought enhances ...horizontal transmission by dampening the basal immunity of plants, which triggers symptom expression and vector manipulation. The potato yellow vein virus (PYVV) causes potato yellow vein disease (PYVD), a re‐emerging epidemic of potato crops in South America, and is transmitted horizontally by the greenhouse whitefly (GWF), Trialeurodes vaporariorum (Hemiptera: Aleyrodidae), or vertically through infected seed tubers. We investigated the role of drought and temperature as modulators of PYVD symptom expression, plant immune response, and vector survival, development and host preference. We found that drought induced symptom expression, suppressed the salicylic acid pathway and increased PYVV replication. GWF survival was reduced on PYVV‐infected hosts and development was slowest when they fed on plants with PYVD symptoms, which also triggered adults’ attraction to PYVV‐infected plants. However, adults previously fed on infected plants showed the opposite effect, being more attracted to PYVV‐free plants. We propose a theoretical model that explains the role of drought in modulating potato–PYVV–GWF interactions and provides new insights into plant–virus–vector coevolution.
Drought episodes may drive viral epidemics by modulating plant defence response, disease symptom expression and vector behaviour and population dynamics.
ABSTRACT
The $P\dot{P}$ diagram is a cornerstone of pulsar research. It is used in multiple ways for classifying the population, understanding evolutionary tracks, identifying issues in our ...theoretical reach, and more. However, we have been looking at the same plot for more than five decades. A fresh appraisal may be healthy. Is the $P \dot{P}$-diagram the most useful or complete way to visualize the pulsars we know? Here we pose a fresh look at the information we have on the pulsar population. First, we use principal component analysis over magnitudes depending on the intrinsic pulsar’s timing properties (proxies to relevant physical pulsar features), to analyse whether the information contained by the pulsar’s period and period derivative is enough to describe the variety of the pulsar population. Even when the variables of interest depend on P and $\dot{P}$, we show that $P \dot{P}$ are not principal components. Thus, any distance ranking or visualization based only on P and $\dot{P}$ is potentially misleading. Next, we define and compute a properly normalized distance to measure pulsar nearness, calculate the minimum spanning tree of the population, and discuss possible applications. The pulsar tree hosts information about pulsar similarities that go beyond P and $\dot{P}$, and are thus naturally difficult to read from the $P\dot{P}$-diagram. We use this work to introduce the pulsar tree website containing visualization tools and data to allow users to gather information in terms of MST and distance ranking.
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