Electrophoretic molecular communication with piecewise constant electric field

This paper studies a novel electrophoretic molecular communication (EMC) framework utilizing a piecewise constant electric field. EMC is a particular type of molecular communication that exploits electric fields to induce the movement of charged particles to enhance communication performance. Our previous work proposed an EMC framework utilizing a time-varying electric field that exponentially changes; however, the field with such a complicated shape might be challenging to be implemented in practice. Thus, this paper proposes a new EMC approach exploiting a piecewise constant electric field that can be readily implemented via, e.g., an on/off switch method. We formulate two optimization problems to design the electric field based on different objectives: minimizing a mean squared error and minimizing a bit interval. The solutions of each, such as optimal on-off timings and corresponding strengths of the constant electric fields, are obtained through the Lagrange multiplier approach and the geometric programming, respectively. The Monte Carlo simulation results verify that the proposed piecewise constant electric field significantly reduces the bit error rate relative to the constant field benchmark while performing less well, but not significantly, than the exponential field benchmark

Modelling cassava production and pest management under biotic and abiotic constraints.

We summarise modelling studies of the most economically important cassava diseases and arthropods, highlighting research gaps where modelling can contribute to the better management of these in the areas of surveillance, control, and host-pest dynamics understanding the effects of climate change and future challenges in modelling. For over 30 years, experimental and theoretical studies have sought to better understand the epidemiology of cassava diseases and arthropods that affect production and lead to considerable yield loss, to detect and control them more effectively. In this review, we consider the contribution of modelling studies to that understanding. We summarise studies of the most economically important cassava pests, including cassava mosaic disease, cassava brown streak disease, the cassava mealybug, and the cassava green mite. We focus on conceptual models of system dynamics rather than statistical methods. Through our analysis we identified areas where modelling has contributed and areas where modelling can improve and further contribute. Firstly, we identify research challenges in the modelling developed for the surveillance, detection and control of cassava pests, and propose approaches to overcome these. We then look at the contributions that modelling has accomplished in the understanding of the interaction and dynamics of cassava and its' pests, highlighting success stories and areas where improvement is needed. Thirdly, we look at the possibility that novel modelling applications can achieve to provide insights into the impacts and uncertainties of climate change. Finally, we identify research gaps, challenges, and opportunities where modelling can develop and contribute for the management of cassava pests, highlighting the recent advances in understanding molecular mechanisms of plant defence

Climate-Smart Agriculture and Climate Information Services Action for Food Systems Transformation in Ghana: Capacity strengthening and Stakeholder consultation

AICCRA Ghana Cluster in collaboration with WA Regional Cluster and national, regional and international partners convened a two-week capacity strengthening event. The format of the event was hybrid with important in-person attendance arranged. The training aligns with the clusters expected contributions to specific project targets against four AICCRA performance indicators: PDO1- CCAFS partners and stakeholders in the Project area are increasingly accessing enhanced climate information services and/or validated climate-smart agriculture technologies; IPI 2.2- Partnerships launched/ strengthened between AICCRA-funded CGIAR and NARS scientists, universities, public sector stakeholders, farmer organizations, NGOs and private sector; IPI 2.3- People engaged in AICCRA-funded capacity development activities; and IPI 3.1- Validated climate information services and climate-smart agriculture technologies disseminated / made accessible. Therefore, the training was structured around four main segments: 1) Climate-smart one-health approach and partnership launch; 2) Early Warning & Rapid Response (EWRR) for a climate-smart IPM; 3) NFCS partnership strengthening and stakeholder consultation; 4) Enhancing access to CSA/CIS bundles while addressing gender and social inclusion (GSI)

Electrophoretic Molecular Communication with Time-Varying Electric Fields

This article investigates a novel electrophoretic molecular communication mechanism that utilizes a time-varying electric field, which induces time-varying molecule velocities and in turn improves communication performance. For a sinusoidal field, we specify favorable signal parameters (e.g., phase and frequency) that yield excellent communication link performance. We also analytically derive an optimized field function by formulating an appropriate cost function and solving the Euler-Lagrange equation. In our setup, the field strength is proportional to the molecular velocity; we verify this assumption by solving the Basset-Boussinesq-Oseen equation for a given time-varying electric field (forcing function) and examining its implications for practical physical parameterizations of the system. Our analysis and Monte-Carlo simulation results demonstrate that the proposed time-varying approach can significantly increase the number of information-carrying molecules expected to be observed at the receiver and reduce the bit-error probability compared to the constant field benchmark.Comment: 19 pages, 6 figure

Differential Roles of AC2 and AC4 of Cassava Geminiviruses in Mediating Synergism and Suppression of Posttranscriptional Gene Silencing

Posttranscriptional gene silencing (PTGS) in plants is a natural defense mechanism against virus infection. In mixed infections, virus synergism is proposed to result from suppression of the host defense mechanism by the viruses. Synergistic severe mosaic disease caused by simultaneous infection with isolates of the Cameroon strain of African cassava mosaic virus (ACMV-[CM]) and East African cassava mosaic Cameroon virus (EACMCV) in cassava and tobacco is characterized by a dramatic increase in symptom severity and a severalfold increase in viral-DNA accumulation by both viruses compared to that in singly infected plants. Here, we report that synergism between ACMV-[CM] and EACMCV is a two-way process, as the presence of the DNA-A component of ACMV-[CM] or EACMCV in trans enhanced the accumulation of viral DNA of EACMCV and ACMV-[CM], respectively, in tobacco BY-2 protoplasts. Furthermore, transient expression of ACMV-[CM] AC4 driven by the Cauliflower mosaic virus 35S promoter (p35S-AC4) enhanced EACMCV DNA accumulation by ∼8-fold in protoplasts, while p35S-AC2 of EACMCV enhanced ACMV-[CM] DNA accumulation, also by ∼8-fold. An Agrobacterium-based leaf infiltration assay determined that ACMV-[CM] AC4 and EACMCV AC2, the putative synergistic genes, were able to suppress PTGS induced by green fluorescent protein (GFP) and eliminated the short interfering RNAs associated with PTGS, with a correlated increase in GFP mRNA accumulation. In addition, we have identified AC4 of Sri Lankan cassava mosaic virus and AC2 of Indian cassava mosaic virus as suppressors of PTGS, indicating that geminiviruses evolved differently in regard to interaction with the host. The specific and different roles played by these AC2 and AC4 proteins of cassava geminiviruses in regulating anti-PTGS activity and their relation to synergism are discussed

Contrôle des germes endogènes par usage d’agents antimicrobiens et réponse de différents explants durant la phase d’initiation in vitro de l'ananas (Ananas comosus (L.) Mill var. comosus)

Objectif : La culture in vitro est aujourd’hui utilisée dans la production massive de rejets d’ananas. Mais, la réussite de sa  première phase (initiation) nécessite l’élimination des infections et un bon choix d’explant. Dans la présente étude, l’effet de deux agents antimicrobiens et du type d’explant sur la reprise in vitro de l’ananas a été évalué.Méthodologie et Résultats : Les bourgeons axillaires médians de  couronne d’ananas des cultivars Cayenne lisse (Hilo et Saint Michael) et Pain de sucre ont été ensemencés sur le milieu de Murashige et Skoog additionné de 5 mg/l de Benzylaminopurine : MC. L’hypochlorite de sodium (0,1 ; 0,2 ; 0,3 et 0,4%) et le Chlorothalonil (0,075 ; 0,15 ; 0,225 et 0,3%) ont été incorporés au milieu. Ensuite, des bourgeons axillaires médians de 8 à 10 semaines après floraison et ceux des parties supérieure, médiane et basale de 10 semaines ont été ensemencés sur le milieu MC additionné de 0,3% d’hypochlorite de sodium. La présence d’agent antimicrobien a réduit les infections mais avec une influence négative sur la reprise. L’hypochlorite de sodium à 0,3% a permis une meilleure élimination des infections (17,78%) sans significativement affecter la reprise (78,89%). Les contaminations sont plus prononcées chez Pain de sucre (37,40%) que chez Saint Michael (19,26%) et Hilo (9,63%). Les jeunes bourgeons médians des couronnes de 8 semaines et supérieurs de 10 semaines ont présenté une meilleure aptitude au débourrement avec respectivement des taux de 92,22% et 86,67%.Conclusion et applications : La désinfection de surface généralement effectuée à l’initiation ne permet pas d’éliminer efficacement les  infections chez l’ananas. L’introduction d’agent antimicrobien dans le milieu de culture a réduit les infections mais a eu un effet négatif sur le débourrement aux doses croissantes. L’utilisation des bourgeons axillaires supérieurs et médians de couronne de 8 semaines après floraison est souhaitée pour optimiser la reprise in vitro de l’ananas.Mots clés : Ananas, hypochlorite de sodium, chlorothalonil, position de l’explant, âge de l’explant, désinfection, débourrement

Contrôle des germes endogènes par usage d’agents antimicrobiens et réponse de différents explants durant la phase d’initiation in vitro de l'ananas (Ananas comosus (L.) Mill var. comosus)

Objectif : La culture in vitro est aujourd’hui utilisée dans la production massive de rejets d’ananas. Mais, la réussite de sa  première phase (initiation) nécessite l’élimination des infections et un bon choix d’explant. Dans la présente étude, l’effet de deux agents antimicrobiens et du type d’explant sur la reprise in vitro de l’ananas a été évalué.Méthodologie et Résultats : Les bourgeons axillaires médians de  couronne d’ananas des cultivars Cayenne lisse (Hilo et Saint Michael) et Pain de sucre ont été ensemencés sur le milieu de Murashige et Skoog additionné de 5 mg/l de Benzylaminopurine : MC. L’hypochlorite de sodium (0,1 ; 0,2 ; 0,3 et 0,4%) et le Chlorothalonil (0,075 ; 0,15 ; 0,225 et 0,3%) ont été incorporés au milieu. Ensuite, des bourgeons axillaires médians de 8 à 10 semaines après floraison et ceux des parties supérieure, médiane et basale de 10 semaines ont été ensemencés sur le milieu MC additionné de 0,3% d’hypochlorite de sodium. La présence d’agent antimicrobien a réduit les infections mais avec une influence négative sur la reprise. L’hypochlorite de sodium à 0,3% a permis une meilleure élimination des infections (17,78%) sans significativement affecter la reprise (78,89%). Les contaminations sont plus prononcées chez Pain de sucre (37,40%) que chez Saint Michael (19,26%) et Hilo (9,63%). Les jeunes bourgeons médians des couronnes de 8 semaines et supérieurs de 10 semaines ont présenté une meilleure aptitude au débourrement avec respectivement des taux de 92,22% et 86,67%.Conclusion et applications : La désinfection de surface généralement effectuée à l’initiation ne permet pas d’éliminer efficacement les  infections chez l’ananas. L’introduction d’agent antimicrobien dans le milieu de culture a réduit les infections mais a eu un effet négatif sur le débourrement aux doses croissantes. L’utilisation des bourgeons axillaires supérieurs et médians de couronne de 8 semaines après floraison est souhaitée pour optimiser la reprise in vitro de l’ananas.Mots clés : Ananas, hypochlorite de sodium, chlorothalonil, position de l’explant, âge de l’explant, désinfection, débourrement

Environment Determines Fidelity for an RNA Virus Replicase▿

The rate of insertion and deletion mutations of the replicase of Cucumber mosaic virus (CMV) was determined in planta by using a parasitic satellite RNA (satRNA) as a reporter. We found that the CMV replicase had different fidelity in different environments, with important implications in viral disease evolution. Insertions were very rare events, irrespective of the region of the satRNA genome assayed and independent of the hosts tested. On the other hand, deletion events were more frequent but were restricted to a highly structured region of the reporter. Deletion mutation rates were different for the two hosts tested, although the mutation distribution was not influenced by the hosts. Moreover, hot spots with high mutation rates were identified on the satRNA genome