El piojo harinoso (Phenacoccus sp.) de la yuca; una de las plagas agricolas mas importantes en el mundo

Cassava mealybugs constitute one of the major production problems of cassava in Africa and the Americas. The species already identified that attack cassava in the Americas include Phenacoccus manihoti, P. herreni, P. gossypii, and P. grenadensis. Since its introduction into Africa, P. manihoti has caused considerable yield losses in some regions, especially Zaire. In the Americas, severe outbreaks of P. herreni have been reported in several areas of Brazil, Colombia, and the Guianas. These 2 species are similar taxonomically and in plant damage symptoms but differ biologically. The initial and most severe attack of both species occurs on the growing point of the cassava plant shoots. Plant reaction consists of a rosetting effect on the apical leaves which results in a cabbage-like appearance of the shoot. High mealybug populations, together with the stress caused by drought, cause defoliation, deformation of the shoots, shortening of internodes, and distortion of stems. The bionomics of both species differ in that P. herreni is bisexual and P. manihoti reproduces parthenogenetically. Biological studies on P. herreni show that the female passesthrough 3 instars before the adult stage. The complete life cycle from egg to adult lasts 49.5 days. Males pass through 4 instars before the adult stage, in which the adult male is winged. The whole cycle lasts 29.5 days. The cassava mealybug has numerous natural enemies. Biological control combined with resistance offers a healthy and economical control of the pest. Tables are included on the life cycle of P. herreni and P. gossypii on plants of cassava var. M Col 113 under lab. conditions, size and size increase of P. herreni on cassava under greenhouse conditions, hyperparasites of Phenacoccus spp. in Latin America, populations of natural enemies of the cassava mealybug in the field, and natural enemies of P. gossypii and P. herreni in Latin America and the Caribbean. (AS

Influence of telomerase activity and initial distribution on human follicular aging: Moving from a discrete to a continuum model

Producción CientíficaA discrete model is proposed for the temporal evolution of a population of cells sorted according to their telomeric length. This model assumes that, during cell division, the distribution of the genetic material to daughter cells is asymmetric, i.e. chromosomes of one daughter cell have the same telomere length as the mother, while in the other daughter cell telomeres are shorter. Telomerase activity and cell death are also taken into account. The continuous model is derived from the discrete model by introducing the generational age as a continuous variable in , being the Hayflick limit, i.e. the number of times that a cell can divide before reaching the senescent state. A partial differential equation with boundary conditions is obtained. The solution to this equation depends on the initial telomere length distribution. The initial and boundary value problem is solved exactly when the initial distribution is of exponential type. For other types of initial distributions, a numerical solution is proposed. The model is applied to the human follicular growth from preantral to preovulatory follicle as a case study and the aging rate is studied as a function of telomerase activity, the initial distribution and the Hayflick limit. Young, middle and old cell-aged initial normal distributions are considered. In all cases, when telomerase activity decreases, the population ages and the smaller the value, the higher the aging rate becomes. However, the influence of these two parameters is different depending on the initial distribution. In conclusion, the worst-case scenario corresponds to an aged initial telomere distribution.Ministerio de Ciencia e Innovación (PGC2018-101443-B-I00)CDTI and FEDER (IDI-20190160 and IDI-20181240)Instituto de Salud Carlos III (Spanish Government) (PI20/00252)FINOX through FORWARD 2018-6 to E.V. and J.A.G.V. and by IVIRMA (2004-FIVI-041-MV; 1711-FIVI-111-MV; 1707-FIVI-084-MV; 1711-FIVI-112-MV; 2207-MAD-093-MV)

Trends in phytoplankton species abundance in shelf waters of the Galician upwelling (NW Spain).

Phytoplankton is a sentinel of ecosystem change in marine ecosystems. Composed by many species with different life-history strategies, it rapidly responds to environment changes. An analysis of time-series of the abundance of 54 phytoplankton taxa in Galicia (NW Spain) between 1989 and 2008 to determine the main trends in relation to climate and upwelling showed that most of their variability was stochastic, as seasonality and long term trends accounted for a minor fraction of the series. All trends were non linear, and taxa clustered in 4 groups according to the trend pattern but there was no defined pattern for diatoms, dinoflagellates or flagellates. No clear trend was shown by 23 taxa, 14 taxa decreased and 4 taxa increased during the early 1990s, while only 13 taxa showed a general increase through the series. In contrast, series of local environmental conditions (temperature, stratification, nutrients) and climate-related variables (atmospheric pressure indices, upwelling winds) showed a high fraction of their variability in deterministic seasonality and trends. As a result, each taxa showed independent responses to environmental and climate variablity, measured by generalized additive models. Most taxa showed a positive relationship with nutrient concentrations but only a few showed a direct relationship with stratification and upwelling. Climate variables only had measurable effects on some taxa but no common response emerged. Because its adaptation to frequent disturbances, phytoplankton communities in upwelling ecosystems appear less sensitive to changes in regional climate than communities characterised by short and well defined productive periods.IEO RADIALE

Aerosol deposition of Ba0.8Sr0.2TiO3 thin films

In this work we optimized conditions for aerosol deposition of homogeneous, nanograined, smooth Ba0.8Sr0.2TiO3 thin films. Investigation involved optimization of deposition parameters, namely deposition time and temperature for different substrates. Solutions were prepared from titanium isopropoxide, strontium acetate and barium acetate. Films were deposited on Si (1 0 0) or Si covered by platinum (Pt (1 1 1) /Ti/SiO2/Si). Investigation showed that the best films were obtained at substrate temperature of 85ºC. After deposition films were slowly heated up to 650ºC, annealed for 30 min, and slowly cooled. Grain size of BST films deposited on Si substrate were in the range 40-70 nm, depending on deposition conditions, while the same films deposited on Pt substrates showed mean grain size in the range 35-50 nm. Films deposited under optimal conditions were very homogeneous, crackfree, and smooth with rms roughness lower than 4 nm for both substrates

Rhodium complexes in p-C bond formation: Key role of a hydrido ligand

Olefin hydrophosphanation is an attractive route for the atom-economical synthesis of functionalized phosphanes. This reaction involves the formation of P-C and H-C bonds. Thus, complexes that contain both hydrido and phosphanido functionalities are of great interest for the development of effective and fast catalysts. Herein, we showcase the excellent activity of one of them, [Rh(Tp)H(PMe3)(PPh2)] (1), in the hydrophosphanation of a wide range of olefins. In addition to the required nucleophilicity of the phosphanido moiety to accomplish the P-C bond formation, the key role of the hydride ligand in 1 has been disclosed by both experimental results and DFT calculations. An additional Rh-H··· C stabilization in some intermediates or transition states favors the hydrogen transfer reaction from rhodium to carbon to form the H-C bond. Further support for our proposal arises from the poor activity exhibited by the related chloride complex [Rh(Tp)Cl(PMe3)(PPh2)] as well as from stoichiometric and kinetic studies

Oligonucleotide-based therapy for FTD/ALS caused by the C9orf72 repeat expansion: a perspective

Amyotrophic lateral sclerosis (ALS) is a progressive and lethal disease of motor neuron degeneration, leading to paralysis of voluntary muscles and death by respiratory failure within five years of onset. Frontotemporal dementia (FTD) is characterised by degeneration of frontal and temporal lobes, leading to changes in personality, behaviour, and language, culminating in death within 5–10 years. Both of these diseases form a clinical, pathological, and genetic continuum of diseases, and this link has become clearer recently with the discovery of a hexanucleotide repeat expansion in the C9orf72 gene that causes the FTD/ALS spectrum, that is, c9FTD/ALS. Two basic mechanisms have been proposed as being potentially responsible for c9FTD/ALS: loss-of-function of the protein encoded by this gene (associated with aberrant DNA methylation) and gain of function through the formation of RNA foci or protein aggregates. These diseases currently lack any cure or effective treatment. Antisense oligonucleotides (ASOs) are modified nucleic acids that are able to silence targeted mRNAs or perform splice modulation, and the fact that they have proved efficient in repeat expansion diseases including myotonic dystrophy type 1 makes them ideal candidates for c9FTD/ALS therapy. Here, we discuss potential mechanisms and challenges for developing oligonucleotide-based therapy for c9FTD/ALS

Trans-splenic puncture during percutaneous nephrolithotomy: Outcome spectrum of the same complication

AbstractPercutaneous nephrolithotomy is an endourologic technique commonly used in the management of nephrolithiasis. However, this procedure is not complication-free. Splenic injury is exceptionally rare with a reported rate of 1% from the total case load. We present herein two cases of splenic puncture during percutaneous nephrolithotomy that illustrate two different outcomes. In the first case, the patient remained asymptomatic and was discharged on her third post-operative day after removing the nephrostomy, without any sign of hemodynamic compromise. In the second case, the patient presented with hemodynamic instability and an abdominal computed tomography scan was done that showed free fluid in the peritoneal cavity. Emergency laparotomy was performed and revealed a deep peripheral laceration (20mm×5mm in length) that required splenectomy. After a thorough review of the existing literature, we could find only 11 other instances of injury to the spleen in which treatment outcomes were reported. Patient hemodynamic status was the main factor in deciding on the type of treatment

Expansions of algebras and superalgebras and some applications

After reviewing the three well-known methods to obtain Lie algebras and superalgebras from given ones, namely, contractions, deformations and extensions, we describe a fourth method recently introduced, the expansion of Lie (super)algebras. Expanded (super)algebras have, in general, larger dimensions than the original algebra, but also include the Inonu-Wigner and generalized IW contractions as a particular case. As an example of a physical application of expansions, we discuss the relation between the possible underlying gauge symmetry of eleven-dimensional supergravity and the superalgebra osp(1|32).Comment: Invited lecture delivered at the 'Deformations and Contractions in Mathematics and Physics Workshop', 15-21 January 2006, Mathematisches Forschungsinstitut Oberwolfach, German