Three-dimensional evolution of magnetic and velocity shear driven instabilities in a compressible magnetized jet

The problem of three-dimensional combined magnetic and velocity shear driven instabilities of a compressible magnetized jet modeled with a plane neutral/current double vortex sheet in the framework of the resistive magnetohydrodynamics is addressed. The resulting dynamics given by the stream+current sheet interaction is analyzed and the effects of a variable geometry of the basic fields are considered. Depending on the basic asymptotic magnetic field configuration, a selection rule of the linear instability modes can be obtained. Hence, the system follows a two-stage path developing either through a fully three-dimensional dynamics with a rapid evolution of kink modes leading to a final turbulent state, or rather through a driving two-dimensional instability pattern that develops on parallel planes on which a reconnection+coalescence process takes place.Comment: 33 pages, 15 figures, accepted for publication in Physics of Plasma

Protecting crop species from biotic and abiotic constraints in the era of global change: Are we ready for this challenge?

Reliable andaffordable supply of food is of crucial importance to the progress andstability of human societies. During the last century, we have assisted to anextraordinary increase of crop yields, especially for the most widespread andconsumed crop species, such as rice, wheat, corn and soybean. The Broadbalkexperiment, one of the oldest continuous agronomic experiments in the world,have showed how half of the increase of crop productivity is mainly due to the improvementsintroduced through plant breeding and half through to agronomical practices,although both are dependent on each other (Rasmussen et al., 1998). The development of a huge numbers of scientificplant breeding programs has been of vital relevance in improving crop varietiesand productivity. In addition, collection and spread of improved germplasmaround the world have ensured that all breeders could quickly benefit from theadvances obtained by others. On the other side, based on Lawes and Gilbert'swork in the previous century, the main advances in agronomy consisted on thecontinued use of fertilizers, the true value of which could only be realized inthe presence of suitable varieties and in the absence (or under controlledpressure) of competition from weeds, pest and diseases. Therefore, cropprotection became crucial and it was achieved by the improvements of theagrochemical industry, which has developed sophisticated, high-targeting andmore efficient agrochemicals. Taken together, the use of new high-yieldvarieties in association with chemical fertilizers and agrochemicals,controlled water-supply (irrigation), and new methods of cultivation, includingmechanization, are commonly identified under the term “Green Revolution” which wasconied between ’30 and ’60 and was responsible in some cases for doubling (oreven triplicating) the agricultural production for many crops species, inparticular cereals. The incremented crop productivity hasbrought many social gains, such as reducing the malnutrition, lowering foodprice, increasing food security. Moreover, since the economic sustainability isthe most important factor for the adoption of a crop for farmers (Sgroi et al., 2014; Testa et al., 2015), the increased crop productivity occurred in the lastdecades, has determined a positive impact on the development of several ruralareas. The increase of cropyield, has caused, on the other side, large changes in rural societies due tothe migration of population from the countryside (caused by the decrease ofmanpower needs) to towns and cities where the industrialization offered moreopportunities. The better living conditions lead to the highest increment ofword population that has ever been documented: from 2.5 b people to 5.2 b in 40years (1950-1990; UNR, 2004). Nowadays, word population is predicted toincrease from 7.4 b people (May, 2016), to 8.4 b in 2030 and 9.5 b in 2050 (U.SCensus Bureau). In addition, people rise out of poverty, higher livingstandards, such as greater meat consumption, and personal mobility will increaseeven more the demand on food production (and quality), animal feed, fiber, andfuels. Thus feeding, clothing and fueling a more densely populated planet isprobably the key challenge of our century. Industrializationand anthropic activities have also imposed profound alterations to theenvironment and, decade after decade, have contributed to alter dramaticallythe life conditions on Earth leading to the so called “Global Change” (alsoreferred as “Global Warming” or “Climate Change”), phenomenon from which we areactually trying to run for cover. Based on several reports produced by theIntergovernmental Panel on Climate Change, it emerges as the most hazardouseffects of Global Change, such as rising temperatures and heat waves, prolongedperiods of drought, and incremented levels of pollutants in all the compartmentsof biosphere can cause more frequent and severe fluctuations in cropproductivity, but also can seriously threaten the availability of arable land;for example increasing the amplitude of soil/water salinization or soilerosion. The total surface of arable soil is also undermined by the constantrequirement of lands for human activities that, beyond the direct effect ofoverbuilding, in many cases also increase the pollution of surrounding areas, forexample through the release of heavy metals, hydrocarbons, xenobiotics or otherpollutants in soil, water, and/or in the atmosphere. Global Change alsoinfluences the ecology of weeds, pests and disease, with possible implicationsfor crop protection and pesticide use. The ability of science to makepredictions on the impact of Global Change on ecosystem interactions is limitedbecause models that include multiple interactive effects of Global Change arestill relatively rare and the comprehension of results obtained from modelsystems results quite complicated. For this reason, despite the scientificcommunity concords on the dramatic impact of Global Change on cropproductivity, predictions may have sometimes-different facets depending on theinformation source. Some researchers reported however that in the time span1981-2001, changes in precipitation and increased temperatures have already inducedannual losses of wheat, maize and barley production of about 40 million tons peryear (Lobell and Field, 2007). Thus, beyond future prediction(s) of GlobalChange effect, humanity is still experiencing the effects this phenomenon forat least three decades. It is evident that in a near future akey challenge for humanity is to increase the productivity of crop specieswhile decreasing water supply, the use of fossil fuels, chemical fertilizer,pesticides (and more in general agrochemicals), and other negativeenvironmental inputs. On the other side, less clear is how agriculture’s outputcan increase so substantially without significantly increasing itsenvironmental footprint. Plant physiologyand biochemistry have developed as powerful disciplines during the 20thcentury, but only in a few cases they have led to relevant crop improvement,and in any case, nothing as compared to the amazing gains on crop productivityobtained through the classical genetic breeding from 1930 to 1960. This islikely because the links between the biochemistry and genetics of the processesdescribed were not established, but rather high-yield genotypes were selectedonly for this desired feature lacking to explore the reason on the bases ofthis gain. The situation has changed after the discovery of the DNA structureby Watson and Crick (1953) and even more after ’70, when the first positiveresults with transgenic plants were obtained. From that time onward, theability to control one or few genes has also deepened the knowledge on the biochemicalmechanisms underlying the genetic process that has been modified. This newapproach, associated with the rapid development of “omic” sciences, has thepotentiality to lead to significant advances either in crop yield, quality,and/or plant protection in a near future. The future need for higher cropproductivity must parallel with a reduction of agronomical inputs as in thepast high-yield genotypes have been selected for their performances with highinputs, especially fertilizers and pesticides. Agricultural emissions from cropand livestock production grew from 4.7 billion tons of carbon dioxideequivalents (CO2 eq) in 2001 to over 5.3 billion tons in 2011. Inthe same period, annual emissions from fertilizers increased by 37% and in 2011the world total annual emissions fromsynthetic fertilizers averaged 725 Mt CO2 eq, about 14% of total emissionsfrom agriculture in the same year (Tubiello etal., 2014). Advances in the basic knowledge of plant genetic, physiologyand biochemistry should thereby be address to increase the efficiency of inpututilization by plants in order to reduce the input level. Technologicaladvances on instrumentations, such as precision farming tools (such as GPStracking devices designed for farming), as well as agronomical practices (i.e.advanced organic farming, eco-friendly soil amendments) can also significant contributeto achieve this goal. The extensiveemploy of synthetic pesticides against pests of agricultural and veterinaryimportance, especially in developing countries, lead to important concerns forhuman health and the environment (Desneux etal., 2007; Hemingway and Ranson, 2000; Naqqash et al., 2016). In this scenario, the need for effective and eco-friendlycontrol tools has gained increasing attention in latest years (Benelli, 2015;2016). Besides this, a further challenge for crop and livestock protectionnowadays, is the improvement of the success of biological control programs,developing effective quarantine procedures and proper evaluation of thenon-target effects of biocontrol agents (Hajek et al., 2016). Furthermore, chemoecological knowledgeabout pests and biocontrol agents may represent a valid help to improve integratedpest management strategies. Indeed, foraging kairomones exploited bycarnivorous arthropods have been successfully tested as field lures to attractcarnivores in damaged agricultural habitats. However, practical applications offoraging kairomones seem to be restricted by major concerns including carnivorousarthropod habituation, carnivorous arthropod time-wasting on victim-free crops,exploitation of host-borne cues by hyperparasitoids and lack of foraging kairomones specificity due totri-trophic interactions sharing a given habitat that use identical chemicalsignals, thus confounding species-specific biological control agents (Kaplan,2012). Further research on new applications of physical and chemical signalsexploited by carnivorous arthropods is urgently required. Physical andolfactory cues can be used to experience mass-reared predators and parasitoids,via sensitization or associative learning practices (Giunti et al., 2016). This could help toovercome critical steps in mass rearing of biocontrol organisms and improvebeneficial performances of carnivorous arthropods in the field. In view of the growing scientificinterest on the effects of Global Changes factors on the relationship betweenplant-pest-environment, in this issue a collection of papers focused on thistopic are presented. Beyond awareness of the deleterious impact of GlobalChange, factor which should lead humanity to a wiser use Earth’s resources, we believethat only the in-depth comprehension of mechanisms adopted by crop species toendurance under stress (Landi et al.,2012; 2013; 2014; 2015; Pardossi et al.,2015; Penella et al., 2016; Tattini et al.,2014) associated with new eco-friendly methods to control crop pests anddiseases may represent a way to contrast the effect of Global Change meanwhilewe are attempting to increase crop productivity for supporting the needs of anincreasingly crowded planet

Red-leafed species for urban "greening" in the age of global climate change

AbstractUrban trees provide vital ecosystem services such as mitigating heat island, improving air quality by removing various air pollutants, capturing rainwater, and acting as topsoil carbon storage. The aesthetic value of urban trees is also another feature that has to be considered in the context of urban greening. Classical criteria for the selection of urban trees have to respond to new challenges imposed to the cities in a near future. Global climate change factors increase the harshness of our cities, and thereby the plant resilience to abiotic stresses has also to be seriously considered for planning the urban greening. Red-leafed species, characterized by the permanent presence of foliar anthocyanins, show a greater tolerance to different environmental cues than green-leafed species commonly used in our cities. In addition, red tree species own a great aesthetic value which has been underestimated in the context of urban areas, especially in the harsh Mediterranean cities. In this study, we emphasize the "privilege of being red" from different point of view, in order to drive the attention to the possibility to increase the use of red-leafed species for urban "greening". Some possible negative aspects related to their use are rebutted and the direction of future researches are proposed

Two-point AG codes from one of the Skabelund maximal curves

In this paper, we investigate two-point Algebraic Geometry codes associated to the Skabelund maximal curve constructed as a cyclic cover of the Suzuki curve. In order to estimate the minimum distance of such codes, we make use of the generalized order bound introduced by P. Beelen and determine certain two-point Weierstrass semigroups of the curve.Comment: 15 page

Physiological Cybernetics: An Old-Novel Approach for Students in Biomedical Systems

Wiener in a seminal book (Wiener, 1948) associated the ancient Greek word ‘κυβερνητικος’ to the control of physiological systems. “Thus, as far back as four years ago, the group of scientists about Dr. Rosenblueth and myself had already become aware of the essential unity of the set of problems centering about communication, control and statistical mechanics, whether in the machine or in the living tissue. [...] We have decided to call the entire field [...] by the name Cybernetics, which we form from the Greek κυβερνητης or steersman. In choosing this term, we wish to recognize that the first significant paper on feed-back mechanisms is an article on governors, which was published by Clerk Maxwell in 1868 and that governor is derived from a Latin corruption of κυβερνητης. We also wish to refer to the fact that the steering engines of a ship are indeed one of the earliest and best developed forms of feed-back mechanisms.” The increasing knowledge in each sector of science led to a huge diversification of scientific research, especially in a borderline sector like cybernetics applied to physiological systems. A first problem to solve was the following: let’s suppose that two groups, one with a control engineering experience and the other one with a medical background (e.g., physicians), decide to cooperate, because they strongly believe that a joined research could be useful for developing mathematical and statistical models. Usually physicians do not have enough time to study and apply advanced modelling. Wiener approached the communication between scientists belonging to different disciplines: “If a physiologist, who knows no mathematics, works together with a mathematician, who knows no physiology, the one will be unable to state his problem in terms that the other can manipulate, and the second will be unable to put the answers in any form that the first can understand. [...] The mathematician need not have the skill to conduct a physiological experiment, but he must have the skill to understand one, to criticize one, and to suggest one. The physiologist need not be able to prove a certain mathematical theorem, but he must be able to grasp its physiological significance and to tell the mathematician for what he should look.” A correct interaction in terms of a clear communication and reciprocal comprehension of the objectives of the research activity between groups with different competences is a crucial aspect in any interdisciplinary research. In 2003 at the University of Pisa it was decided to introduce a new course for undergraduate students in biomedical engineering, based on the Wiener ‘utopia’, in order to teach a novel discipline useful for helping biomedical students to communicate and cooperate effectively with physicians. We named this new course as Physiological Cybernetics, remembering the old Wiener definition. The organization of this course was a difficult task, and it required to gain experience in order to integrate so different disciplines and to produce a common language between students in biomedical engineer and physicians. At a first glance this attempt seemed to be too ambitious, because the different approaches of biomedical engineers with respect to physicians seemed incompatible and even the languages of the two groups were so different to remember the Babel tower… A great deal of effort and attention was required to produce appealing and stimulating lectures, but after many years we can affirm that this challenge is successful, especially for the enthusiastic answers of the students: their number was increasing year after year (about seventy students per year are now attending the course). A strict and trusted cooperation between different groups of physicians is growing up and several groups of physicians belonging to different medical fields are going to join us for new interactions. The aim of this chapter is to describe how the approach to physiological cybernetics has led to integrate academic lessons with research activities. To be more specific, the basic idea of Physiological Cybernetics was to search for models able to emulate physiological systems based on the feedback theory and/or the system theory. In fact, recently, the widespread use of friendly software packages for modelling, along with the development of powerful identification and control techniques has led to a renewed interest in control (Khoo, 2011; Hoppensteadt & Peskin, 2002; Cobelli & Carson, 2008) and identification (Westwick & Kearney, 2003) of physiological systems. Unfortunately physiological systems are intrinsically time variant and highly non linear. Moreover, an effective balance of the model complexity is a difficult task: low order models are usually too simple to be useful, on the other hand high order models are too complex for simulation purposes and they have too many unknown parameters to be identified. Each model selected for investigation was studied by a group of biomedical students supervised by physicians. Each model required several iterations and reformulations, due to the continuous adjustment of the research objectives, changing their final horizon, because of the gap between experimental data and theoretical models, so that the answers to the doubts and questions were continuously moving with the obtained partial results. A final goal of the research was to apply a mathematical framework for helping medical diagnostic techniques and for testing new therapeutic protocols. The procedure of model extraction followed two main pathways: the first one (pathway A) led to a formulation of a mathematical model usually based on differential equations and on an as deep as possible insight into physiological mechanisms (Marmarelis, 2004; Ottesen et al., 2004; Edelstein-Keshet, 2005; Jones et al., 2009) via a physical description of the system. The second one (pathway B) was founded on a model description based on a black-box and data-driven identification (Westwick & Kearney, 2003; Cobelli & Carson, 2008), usually leaving to stochastic models with a parametric or non-parametric structure (Ljung, 1987), depending on the a-priori knowledge of constitutive laws governing the observed system. In this paper we will describe two examples of research activity based on the Physiological Cybernetics, both of them addressed to produce a biomedical framework for predicting the effects of therapeutic actions, but following the two different pathways. The first example follows a statistical non parametric approach, the second one a mathematical model based on differential equations

analyzing the environmental sustainability of glass bottles reuse in an italian wine consortium

Abstract The wine production constitutes an important sector for the Italian economy. Most of the wine producers are associated in local consortiums, which include small family companies involved in the production of similar products. This study aims to investigate the implementation of circular economy opportunities in the wine production chain. In particular, the reuse of glass bottles in the Piceno wine consortium (central Italy) has been analyzed to quantify the potential environmental benefits. The standard Life Cycle Assessment (LCA) methodology has been used to compare the standard scenario (recycle of glass) against the circular scenario (cleaning and reuse of bottles within the local consortium). Results demonstrate that the reuse of glass bottles leads to relevant benefits in all the considered impact categories (ReCiPe Midpoint method). The avoided use of virgin glass offsets the additional resources (e.g. energy) consumed during the cleaning of used bottles

How Does Chloroplast Protect Chlorophyll Against Excessive Light?

Chlorophylls (Chls) are the most abundant plant pigments on Earth. Chls are located in the membrane of thylakoids where they constitute the two photosystems (PSII and PSI) of terrestrial plants, responsible for both light absorption and transduction of chemical energy via photosynthesis. The high efficiency of photosystems in terms of light absorption correlates with the need to protect themselves against absorption of excess light, a process that leads to the so-called photoinhibition. Dynamic photoinhibition consists of the downregulation of photosynthesis quantum yield and a series of photo-protective mechanisms aimed to reduce the amount of light reaching the chloroplast and/or to counteract the production of reactive oxygen species (ROS) that can be grouped in: (i) the first line of chloroplast defence: non-photochemical quenching (NPQ), that is, the dissipation of excess excitation light as heat, a process that takes place in the external antennae of PSII and in which other pigments, that is carotenoids, are directly involved; (ii) the second line of defence: enzymatic antioxidant and antioxidant molecules that scavenge the generated ROS; alternative electron transport (cyclic electron transport, pseudo-cyclic electron flow, chlororespiration and water-water cycle) can efficiently prevent the over-reduction of electron flow, and reduced ferredoxin (Fd) plays a key role in this context

Can Anthocyanins be Part of the Metal Homeostasis Network in Plant?

Anthocyanins are a class of flavonoids with a high level of diversification and likely the most studied pathway of secondary metabolism in Plantae. Anthocyanins have raised a growing interest due to the huge variability of their chemical structures and the more new anthocyanins are isolated from plants, the more questions on their evolutionary and ecological meaning they raise. Antioxidant, photoprotection against high light and UV, defence against herbivores and pathogens, attraction of pollinator are only some proposed biological functions for those versatile compounds. Anthocyanins have also been found complexed with metal ions either in flower pigments (commelin and protocyanin) or in leaves and stems. Due to the potentiality of anthocyanins to chelate to metals, their involvement in the attenuation of metal toxicity has been recently proposed. Conversely, the ability of plants to remobilize metal ions from stored metal-anthocyanin complexes when plants experience a period of transient metal shortage has never been investigated before. The aim of this paper is to support the hypothesis that the anthocyanin-metal interactions might represent a further ecological role for these pigments and also that anthocyanins can be part of the complex network of metal homeostasis in plant