Propiedades estructurales en 2-digrafos de Cayley óptimos sobre grupos abelianos finitos

En este trabajo se presentan algunas propiedades estructurales de los digrafos de Cayley de grado dos con diámetro óptimo, sobre grupos finitos abelianos. En particular, cuando el grupo no es cíclico, todos los digrafos cociente tienen diámetro óptimo. También se dan condiciones para obtener expansiones de estos digrafos con diámetro óptimo. La herramienta principal para obtener estos resultados es una forma geométrica plana, asociada al digrafo, conocida como diagrama de distancias m´ınimas.Postprint (published version

CTP promotes efficient ParB-dependent DNA condensation by facilitating one-dimensional diffusion from parS

Faithful segregation of bacterial chromosomes relies on the ParABS partitioning system and the SMC complex. In this work, we used single-molecule techniques to investigate the role of cytidine triphosphate (CTP) binding and hydrolysis in the critical interaction between centromere-like parS DNA sequences and the ParB CTPase. Using a combined optical tweezers confocal microscope, we observe the specific interaction of ParB with parS directly. Binding around parS is enhanced by the presence of CTP or the non-hydrolysable analogue CTPγS. However, ParB proteins are also detected at a lower density in distal non-specific DNA. This requires the presence of a parS loading site and is prevented by protein roadblocks, consistent with one-dimensional diffusion by a sliding clamp. ParB diffusion on non-specific DNA is corroborated by direct visualization and quantification of movement of individual quantum dot labelled ParB. Magnetic tweezers experiments show that the spreading activity, which has an absolute requirement for CTP binding but not hydrolysis, results in the condensation of parS-containing DNA molecules at low nanomolar protein concentrations

Clinical Consensus Guideline on the Management of Phaeochromocytoma and Paraganglioma in Patients Harbouring Germline SDHD Pathogenic Variants

Patients with germline SDHD pathogenic variants (encoding succinate dehydrogenase subunit D; ie, paraganglioma 1 syndrome) are predominantly affected by head and neck paragangliomas, which, in almost 20% of patients, might coexist with paragangliomas arising from other locations (eg, adrenal medulla, para-aortic, cardiac or thoracic, and pelvic). Given the higher risk of tumour multifocality and bilaterality for phaeochromocytomas and paragangliomas (PPGLs) because of SDHD pathogenic variants than for their sporadic and other genotypic counterparts, the management of patients with SDHD PPGLs is clinically complex in terms of imaging, treatment, and management options. Furthermore, locally aggressive disease can be discovered at a young age or late in the disease course, which presents challenges in balancing surgical intervention with various medical and radiotherapeutic approaches. The axiom-first, do no harm-should always be considered and an initial period of observation (ie, watchful waiting) is often appropriate to characterise tumour behaviour in patients with these pathogenic variants. These patients should be referred to specialised high-volume medical centres. This consensus guideline aims to help physicians with the clinical decision-making process when caring for patients with SDHD PPGLs

Conservation and Diversity of Seed Associated Endophytes in Zea across Boundaries of Evolution, Ethnography and Ecology

Endophytes are non-pathogenic microbes living inside plants. We asked whether endophytic species were conserved in the agriculturally important plant genus Zea as it became domesticated from its wild ancestors (teosinte) to modern maize (corn) and moved from Mexico to Canada. Kernels from populations of four different teosintes and 10 different maize varieties were screened for endophytic bacteria by culturing, cloning and DNA fingerprinting using terminal restriction fragment length polymorphism (TRFLP) of 16S rDNA. Principle component analysis of TRFLP data showed that seed endophyte community composition varied in relation to plant host phylogeny. However, there was a core microbiota of endophytes that was conserved in Zea seeds across boundaries of evolution, ethnography and ecology. The majority of seed endophytes in the wild ancestor persist today in domesticated maize, though ancient selection against the hard fruitcase surrounding seeds may have altered the abundance of endophytes. Four TRFLP signals including two predicted to represent Clostridium and Paenibacillus species were conserved across all Zea genotypes, while culturing showed that Enterobacter, Methylobacteria, Pantoea and Pseudomonas species were widespread, with γ-proteobacteria being the prevalent class. Twenty-six different genera were cultured, and these were evaluated for their ability to stimulate plant growth, grow on nitrogen-free media, solubilize phosphate, sequester iron, secrete RNAse, antagonize pathogens, catabolize the precursor of ethylene, produce auxin and acetoin/butanediol. Of these traits, phosphate solubilization and production of acetoin/butanediol were the most commonly observed. An isolate from the giant Mexican landrace Mixteco, with 100% identity to Burkholderia phytofirmans, significantly promoted shoot potato biomass. GFP tagging and maize stem injection confirmed that several seed endophytes could spread systemically through the plant. One seed isolate, Enterobacter asburiae, was able to exit the root and colonize the rhizosphere. Conservation and diversity in Zea-microbe relationships are discussed in the context of ecology, crop domestication, selection and migration

Propiedades estructurales en 2-digrafos de Cayley óptimos sobre grupos abelianos finitos

En este trabajo se presentan algunas propiedades estructurales de los digrafos de Cayley de grado dos con diámetro óptimo, sobre grupos finitos abelianos. En particular, cuando el grupo no es cíclico, todos los digrafos cociente tienen diámetro óptimo. También se dan condiciones para obtener expansiones de estos digrafos con diámetro óptimo. La herramienta principal para obtener estos resultados es una forma geométrica plana, asociada al digrafo, conocida como diagrama de distancias m´ınimas

Data-flow driven optimal tasks distribution for global heterogeneous systems

As a result of advances in technology and highly demanding users expectations, more and more applications require intensive computing resources and, most importantly, high consumption of data distributed throughout the environment. For this reason, there has been an increasing number of research efforts to cooperatively use geographically distributed resources, working in parallel and sharing resources and data. In fact, an application can be structured into a set of tasks organized through interdependent relationships, some of which can be effectively executed in parallel, notably speeding up the execution time. In this work a model is proposed aimed at offloading tasks execution in heterogeneous environments, considering different nodes computing capacity connected through distinct network bandwidths, and located at different distances. In the envisioned model, the focus is on the overhead produced when accessing remote data sources as well as the data transfer cost generated between tasks at run-time. The novelty of this approach is that the mechanism proposed for tasks allocation is data-flow aware, considering the geographical location of both, computing nodes and data sources, ending up in an optimal solution to a highly complex problem. Two optimization strategies are proposed, the Optimal Matching Model and the Staged Optimization Model, as two different approaches to obtain a solution to the task scheduling problem. In the optimal model approach a global solution for all application’s tasks is considered, finding an optimal solution. Differently, the staged model approach is designed to obtain a local optimal solution by stages. In both cases, a mixed integer linear programming model has been designed intended to minimizing the application execution time. In the studies carried out to evaluate this proposal, the staged model provides the optimal solution in 76% of the simulated scenarios, while it also dramatically reduces the solving time with respect to optimal. Both models have pros and cons and, in fact, can be used together to complement each other. The optimal model finds the global optimal solution at high running time cost, which makes this model unpractical on some scenarios. The staged model instead, is faster enough to be used on those scenarios; however, the given solution might not be optimal in some cases.Peer ReviewedPostprint (author's final draft

A preliminary model for optimal load distribution in heterogeneous smart environments

Smart cities are becoming popular and, with them, a plethora of resources is emerging turning into a massive concentration of computing devices. In such environments, the deployment of a smart resources management system is envisioned as an extraordinary opportunity to provide almost unlimited computing and networking capabilities obtained by putting together a vast set of nearby devices, hence offering high performance computing while benefiting from low latency networking. In this scenario, where millions of highly heterogeneous devices are available, a key challenge is to select the set of devices suited the most to carry out some specific tasks. In this paper, we present a performance estimation model intended to find an optimal solution for load distribution over massive heterogeneous systems, considering the effects of both, distributed computing and network overhead. The current implementation is in a preliminary stage, considering only fully parallel applications. Trials conducted considering several hardware configurations, with either homogeneous or heterogeneous systems, show the fact that the predicted performance matches the one obtained by the experimental executions with an almost negligible deviation. These initial results encourage us to continue developing the model for more complex and realistic applications.Peer Reviewe

A preliminary model for optimal load distribution in heterogeneous smart environments

Smart cities are becoming popular and, with them, a plethora of resources is emerging turning into a massive concentration of computing devices. In such environments, the deployment of a smart resources management system is envisioned as an extraordinary opportunity to provide almost unlimited computing and networking capabilities obtained by putting together a vast set of nearby devices, hence offering high performance computing while benefiting from low latency networking. In this scenario, where millions of highly heterogeneous devices are available, a key challenge is to select the set of devices suited the most to carry out some specific tasks. In this paper, we present a performance estimation model intended to find an optimal solution for load distribution over massive heterogeneous systems, considering the effects of both, distributed computing and network overhead. The current implementation is in a preliminary stage, considering only fully parallel applications. Trials conducted considering several hardware configurations, with either homogeneous or heterogeneous systems, show the fact that the predicted performance matches the one obtained by the experimental executions with an almost negligible deviation. These initial results encourage us to continue developing the model for more complex and realistic applications.Peer ReviewedPostprint (published version