Soil microbiota manipulation and its role in suppressing soil-borne plant pathogens in organic farming systems under the light of microbiome-assisted strategies

AbstractSoil microbiota plays a key role in suppressing soil-borne plant pathogens improving the natural soil suppressiveness. Microbiome disturbance triggers specific perturbation to change and shape the soil microbial communities' network for increasing suppression against phytopathogens and related diseases. Very important goals have been reached in manipulation of soil microbiota through agronomical practices based on soil pre-fumigation, organic amendment, crop rotation and intercropping. Nevertheless, to limit inconsistencies, drawbacks and failures related to soil microbiota disturbance, a detailed understanding of the microbiome shifts during its manipulation is needed under the light of the microbiome-assisted strategies. Next-generation sequencing often offers a better overview of the soil microbial communities during microbiomes manipulation, but sometime it does not provide information related to the highest taxonomic resolution of the soil microbial communities. This review work reports and discusses the most reliable findings in relation to a comprehensive understanding of soil microbiota and how its manipulation can improve suppression against soil-borne diseases in organic farming systems. Role and functionality of the soil microbiota in suppressing soil-borne pathogens affecting crops have been basically described in the first section of the paper. Characterization of the soil microbiomes network by high-throughput sequencing has been introduced in the second section. Some relevant findings by which soil microbiota manipulation can address the design of novel sustainable cropping systems to sustain crops' health without use (or reduced use) of synthetic fungicides and fumigants have been extensively presented and discussed in the third and fourth sections, respectively, under the light of the new microbiome-assisted strategies. Critical comparisons on the next-generation sequencing have been provided in the fifth section. Concluding remarks have been drawn in the last section

Large scale zigzag pattern emerging from circulating active shakers

We report the emergence of large zigzag bands in a population of reversibly actuated magnetic rotors that behave as active shakers, namely squirmers that shake the fluid around them without moving. The shakers collectively organize into dynamic structures displaying self-similar growth and generate topological defects in the form of cusps that connect vortices of rolling particles with alternating chirality. By combining experimental analysis with particle-based simulation, we show that the special flow field created by the shakers is the only ingredient needed to reproduce the observed spatiotemporal pattern. We unveil a self-organization scenario in a collection of driven particles in a viscoelastic medium emerging from the reduced particle degrees of freedom, as here the frozen orientational motion of the shakers

BUSINESS REPORTING AND GOVERNMENT INTERVENTION:THE CASE OF LEBANESE TELECOM SECTOR

For hundreds of years, the financial has been the only focus of corporate reporting. In recent times, business reporting has increasingly become an important development in the field of corporate disclosure for external stakeholders, which has attracted interest also by institutions and regulators. Accordingly, this work aims to analyze and better understand the underlying reasons of government intervention in business reporting and non-financial performance measurements, using the Lebanese context as case study. In Chapter 1, the thesis looks at the rationales, rules, and actions for public sector intervention in the accounting and business reporting. Then, in Chapter 2 the study carries out an extensive review of relevant academic literature in order to locate and evaluate the findings of the present work within a theoretical framework. In this Chapter, the factors affecting the national accounting, the reporting system and their functioning are described. Government intervention in accounting and business reporting is approached under three different research approaches, i.e. the public interest theory, the institutional theory, and the political economy theory. In Chapter 3, the Lebanese institutional context is described in order to provide an understanding of the national accounting context and the associated regulatory environment. In Chapter 4, the thesis examines more in depth a Lebanese case of business reporting, where the Government has decided to impose mandatory ad hoc non-financial measurements and disclosures on Telecom Companies for control and incentive purposes. The primary research method is based on surveys that have been sent first to the Government (Ministry of Telecommunications), and then to the two private mobile 3 operator companies (MIC1 and MIC2), which are managing the state-owned network through fiduciary management contracts. The research is also carried out using semi-structured interviews to, and email exchanges with, the main institutional and corporate actors. The conceptual framework applied for understanding Key Performance Indicators and their disclosure is rooted on the Concept Paper of WICI (World Intellectual Capital Initiative) Network titled “KPIs in Business Reporting” (www.wici-global.com) as well as on the WICI KPIs for Telecommunication sector. The Chapter investigates how the Lebanese government has addressed the issue of transparency and ensuring financial and non-financial reporting compliance, as well as its preferential reasons for an interventionist approach, which reflects the today’s growing importance of State presence in the field of Business Reporting rather than in the more “traditional” Financial Reporting. In Chapter 5, the research questions are reviewed, and compared and contrasted with the findings of the work. Answers, explanations, and justifications in relation to the literature review are provided. A general assessment of Lebanese government intervention in business reporting is undertaken to evaluate how successful such governmental decision and action have been on improving the performance of the Lebanese telecom sector. The Lebanese is considered to be an interesting case, because it addresses a government’s call for more information on Telecom companies’ “hidden” factors and wealth, which - through selected KPIs - has had the unintended consequence of bringing about and making emerge a new knowledge and pattern of visibility on corporate intangibles in a geographical region where official guidelines on IC Reporting are still absent. There is clearly a great deal of further research work to be done in the Middle East region, if we are to increase our understanding of the ways in which IC reporting can work in these national and organizational settings, while contributing to a better transparency and economic development of that geo-economic area

Retraction of thin films coated by insoluble surfactants

We investigate the retraction of a circular thin film coated with insoluble surfactants, which is punctured at its centre. We assume that the surface pressure of the liquid-gas interface is related to the number density of surfactants through a linear equation of state, which is characterized by a single parameter: the Gibbs dilation modulus. To solve the governing equations and track the deformation of the domain, we use the finite element method with an arbitrary Lagrangian-Eulerian approach where the film surface is sharp. Our simulations show that the surface elasticity introduced by the surfactants slows down the retraction and introduces oscillations at early times. In agreement with previous experiments and theoretical analysis, we find that the presence of surfactants introduces perturbations of the film thickness over progressively larger distances as the surface elasticity increases. The surface perturbations travel faster than the retracting edge of the film at a speed proportional to the Gibbs modulus. For large values of the Gibbs modulus, the interface behaviour approaches that of an incompressible two-dimensional solid. Our analysis sheds light on the effect of insoluble surfactants on the opening of a circular hole in a thin film and can be extended to investigate the onset of surface cracks and fractures. © 2022 Author

Dynamic organization of ligand-grafted nanoparticles during adsorption and surface compression at fluid-fluid interfaces

Monolayers of ligand-grafted nanoparticles at fluid interfaces exhibit a complex response to deformation due to an interplay of particle rearrangements within the monolayer, and molecular rearrangements of the ligand brush on the surface of the particles. We use grazing-incidence small-angle X-ray scattering (GISAXS) combined with pendant drop tensiometry to probe in situ the dynamic organization of ligand-grafted nanoparticles upon adsorption at a fluid–fluid interface, and during monolayer compression. Through the simultaneous measurements of interparticle distance, obtained from GISAXS, and of surface pressure, obtained from pendant drop tensiometry, we link the interfacial stress to the monolayer microstructure. The results indicate that, during adsorption, the nanoparticles form rafts that grow while the interparticle distance remains constant. For small-amplitude, slow compression of the monolayer, the evolution of the interparticle distance bears a signature of ligand rearrangements leading to a local decrease in thickness of the ligand brush. For large-amplitude compression, the surface pressure is found to be strongly dependent on the rate of compression. Two-dimensional Brownian dynamics simulations show that the rate-dependent features are not due to jamming of the monolayer, and suggest that they may be due to out-of-plane reorganization of the particles (for instance expulsion or buckling). The corresponding GISAXS patterns are also consistent with out-of-plane reorganization of the nanoparticles

Theory of active self-organization of dense nematic structures in actin gels

The actin cytoskeleton is remarkably adaptable and multifunctional. It often organizes into nematic bundles such as contractile rings or stress fibers. However, how a uniform and isotropic actin gel self-organizes into dense nematic bundles is not understood. Here, using an active gel model accounting for nematic order and density variations, we identify a novel active patterning mechanism leading to dense nematic structures. Linear stability analysis and nonlinear finite element simulations establish the conditions for nematic bundle self-assembly and how active gel parameters control the architecture, orientation, connectivity and dynamics of self-organized patterns. Finally, we substantiate with discrete network simulations the main requirements for nematic bundle formation according to our theory, namely increased active tension perpendicular to the nematic direction and generalized active forces conjugate to nematic order. Our work portrays actin gels a reconfigurable active materials with a spontaneous tendency to develop patterns of dense nematic bundles.Comment: 11 pages, 4 figures, 1 supplementary PDF, 8 supplementary video

Self-Propulsion of Active Colloids via Ion Release: Theory and Experiments

We study the self-propulsion of a charged colloidal particle that releases ionic species using theory and experiments. We relax the assumptions of thin Debye length and weak nonequilibrium effects assumed in classical phoretic models. This leads to a number of unexpected features that cannot be rationalized considering the classic phoretic framework: an active particle can reverse the direction of motion by increasing the rate of ion release and can propel even with zero surface charge. Our theory predicts that there are optimal conditions for self-propulsion and a novel regime in which the velocity is insensitive to the background electrolyte concentration. The theoretical results quantitatively capture the salt-dependent velocity measured in our experiments using active colloids that propel by decomposing urea via a surface enzymatic reaction

Analysis of dynamic mechanical response in torsion

We investigate the dynamic response of industrial rubbers (styrene-butadiene random copolymers, SBR) in torsion and compare against common small amplitude oscillatory shear measurements by using a torsion rectangular fixture, a modified torsion cylindrical fixture, and a conventional parallel plate fixture, respectively, in two different rheometers (ARES 2kFRTN1 from TA Instruments, USA and MCR 702 from Anton Paar-Physica, Austria). The effects of specimen geometry (length-to-width aspect ratio) on storage modulus and level of clamping are investigated. For cylindrical specimens undergoing torsional deformation, we find that geometry and clamping barely affect the shear moduli, and the measurements essentially coincide with those using parallel plates. In contrast, a clear dependence of the storage modulus on the aspect ratio is detected for specimens having rectangular cross section. The empirical correction used routinely in this test is based on geometrical factors and can account for clamping effects, but works only for aspect ratios above a threshold value of 1.4. By employing a finite element analysis, we perform a parametric study of the effects of the aspect ratio in the cross-sectional stress distribution and the linear viscoelastic torsional response. We propose a new, improved empirical equation for obtaining accurate moduli values in torsion at different aspect ratios, whose general validity is demonstrated in both rheometers. These results should provide a guideline for measurements with different elastomers, for which comparison with dynamic oscillatory tests may not be possible due to wall slip issues

Recurrent Canine Paraphimosis: Modified Surgical Approach

Background: Paraphimosis is characterized by persistent penile exposure, due to the inability to retract the penis into the prepuce.This persistent exposure of a non-erect penis might result from traumas, infections, neoplasia, anatomic or neurological alterations, or even occur in its idiopathic form. Surgical treatment is indicated when it is not possible to keep the penis covered by the foreskin by trying it manually. The surgical techniques described are efficient in small exposures, however, when these are over 1.5 cm, surgical success might become a challenge. The objective of this study is to report a modified surgical approach to solve a 5 cm recurrent paraphimosis in a dog.Case: A 1-year-old male unneuteredmixed-breed dog, weighing 26 kg, waspresented for examination with a historypersistent paraphimosis background for around 2 months without apparent cause. The animal’s tutor reported that it had been submitted to 2 unsuccessful surgical procedures. When the reproductive system was examined, the animal showed a flaccid penis with 5 cm exposure outside the foreskin. A conservative treatment was used, which was also unsuccessful. The next step was a surgical procedure that used the combination of techniques, namely, phallopexy, preputial advancement and reconstruction preputial opening with suture along with orchiectomy. After 10 days, dehiscence of the ostium stitches occurred, which required debridement and new suture. However, it was not efficient and recurrence of the paraphimosis was observed. After 1 month, a new surgery was performed by adapting the phallopexy technique, which was carried out bilaterally and associated to the reconstruction preputial opening with captonated suture, which presented a successful outcome. After 8 months as of the last procedure, the patient is healthy and has no signs of paraphimosis recurrence.Discussion: No consensus has been achieved regarding the paraphimosis treatment, and the resolution of such disorder remains a challenge. For this reason, some parameters should be considered to minimize failure when choosing the surgical technique and, consequently, the recurrence of such condition. Tissue viability, morphological alterations, time of exposure, previous surgeries, and the length of the penis exposure are some of the criteria that must be taken into consideration when choosing the surgical technique. In this case, the first choice was the association of techniques that included preputial advancement, phallopexy and suture preputial opening due to the fact that the exposure was over 1.5 cm and for the existence of a preputial ostium defect, which justified its suture. Despite these associations, paraphimosis recurrence was observed and some of the probable causes include the inadequate position of the penis inside the foreskin flap during the phallopexy and lack of preputial integrity in its ventral aspect. The preputial advancement performed was not sufficient to prevent the exposure or reduce it in the recurrence of the condition, showing that the shortening of preputial muscles and the skin tension might loosen up with time. The second surgery employed bilateral phallopexy without penis exposure to guarantee its correct position, more caudal within the foreskin at the moment of the fixation. The ostium captonated suture also had a relevant role in the tension distribution up to the full tissue healing. New surgical approaches might be needed to achieve success in the paraphimosis treatment. In this report, the length of the penis exposure and the ostium defect were complicating factors. However, the association of the modified surgical techniques resulted in a successful resolution of the condition.  Keywords: phallopexy, prepuce, penis, preputial advancement.Descritores: falopexia, prepúcio, pênis, avanço prepucial.Título:  Parafimose canina recidivante: abordagem cirúrgica modificada.

Simulaciones numéricas de dinámica de ADN en células

El ADN es un polímero que codifica la información genética de los seres vivos, presente en el núcleo de células eucariotas; en condiciones normales se encuentra compactado en torno a unas estructuras llamadas histonas. Las deformaciones mecánicas de las células y fuerzas externas (principalmente comprimir o estirar el núcleo celular) pueden modificar la conformación del ADN y dar lugar a patologías genéticas, proliferación de cáncer y dañar la información genética. A pesar de su importancia para el correcto funcionamiento y desarrollo de las células, el efecto de fuerzas externas en la organización del ADN es todavía desconocido. En este trabajo se pretende crear un modelo computacional simple para el polímero de ADN, evaluar las fuerzas críticas que el ADN puede soportar antes de perder su conformación así como comprobar si el modelo predice o no que el polímero experimente un comportamiento auxético por aplicación de fuerzas externas de estiramiento, asociado a una descondensación parcial del ADN. <br /