A combinatorial model for computing volumes of flow polytopes

We introduce new families of combinatorial objects whose enumeration computes volumes of flow polytopes. These objects provide an interpretation, based on parking functions, of Baldoni and Vergne's generalization of a volume formula originally due to Lidskii. We recover known flow polytope volume formulas and prove new volume formulas for flow polytopes that were seemingly unapproachable. A highlight of our model is an elegant formula for the flow polytope of a graph we call the caracol graph. As by-products of our work, we uncover a new triangle of numbers that interpolates between Catalan numbers and the number of parking functions, we prove the log-concavity of rows of this triangle along with other sequences derived from volume computations, and we introduce a new Ehrhart-like polynomial for flow polytope volume and conjecture product formulas for the polytopes we consider.Comment: 34 pages, 15 figures. v2: updated after referee reports; includes a proof of Proposition 8.7. Accepted into Transactions of the AM

Caracterización de la prevalencia de hallazgos compatibles con hidatidosis y fertilidad de quistes hidatídicos en bovinos de una planta faenadora de la cuidad de Curicó, Chile

The aim of this study was to determine the prevalence of findings compatible with hydatidosis and fertility of hydatid cysts in bovines of a slaughterhouse in Curicó, Chile. Lungs, livers, hearts, spleens and kidneys of 218 animals slaughtered in April 2017 were analyzed. The prevalence of findings compatible with hydatidosis was 12.4%, where 74.1% of affected animals presented lung cysts, 11.1% liver cysts and 14.8% of both types. Older animals concentrated the greatest number of findings. In samples of hydatid fluid from unilocular cysts a fertility of 6.25% was obtained. The prevalence of findings found was lower than the data described in national studies.  En el presente estudio se determinó la prevalencia de hallazgos compatibles con hidatidosis y fertilidad de quistes hidatídicos en bovinos de una planta faenadora en Curicó, Chile. Se analizaron pulmones, hígados, corazones, bazos y riñones de 218 animales faenados en abril de 2017. Se determinó una prevalencia de hallazgos compatibles con hidatidosis de 12.4%, donde el 74.1% de los animales afectados presentó quistes pulmonares, 11.1% quistes hepáticos y 14.8% de ambos tipos. Los animales añosos concentraron la mayor cantidad de hallazgos. En muestras del líquido hidatídico de quistes uniloculares se obtuvo una fertilidad de 6.25%. La prevalencia de hallazgos encontrada fue inferior a los datos descritos en estudios nacionales

Overlapping demyelinating syndromes and anti-NMDA receptor encephalitis

Objective: To report the clinical, radiological, and immunological association of demyelinating disorders with anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis. Methods: Clinical and radiological analysis was done of a cohort of 691 patients with anti-NMDAR encephalitis. Determination of antibodies to NMDAR, aquaporin-4 (AQP4), and myelin oligodendrocyte glycoprotein (MOG) was performed using brain immunohistochemistry and cell-based assays. Results: Twenty-three of 691 patients with anti-NMDAR encephalitis had prominent magnetic resonance imaging (MRI) and/or clinical features of demyelination. Group 1 included 12 patients in whom anti-NMDAR encephalitis was preceded or followed by independent episodes of neuromyelitis optica (NMO) spectrum disorder (5 cases, 4 anti-AQP4 positive) or brainstem or multifocal demyelinating syndromes (7 cases, all anti-MOG positive). Group 2 included 11 patients in whom anti-NMDAR encephalitis occurred simultaneously with MRI and symptoms compatible with demyelination (5 AQ4 positive, 2 MOG positive). Group 3 (136 controls) included 50 randomly selected patients with typical anti-NMDAR encephalitis, 56 with NMO, and 30 with multiple sclerosis; NMDAR antibodies were detected only in the 50 anti-NMDAR patients, MOG antibodies in 3 of 50 anti-NMDAR and 1 of 56 NMO patients, and AQP4 antibodies in 48 of 56 NMO and 1 of 50 anti-NMDAR patients (p < 0.0001 for all comparisons with Groups 1 and 2). Most patients improved with immunotherapy, but compared with anti-NMDAR encephalitis the demyelinating episodes required more intensive therapy and resulted in more residual deficits. Only 1 of 23 NMDAR patients with signs of demyelination had ovarian teratoma compared with 18 of 50 anti-NMDAR controls (p = 0.011). Interpretation: Patients with anti-NMDAR encephalitis may develop concurrent or separate episodes of demyelinating disorders, and conversely patients with NMO or demyelinating disorders with atypical symptoms (eg, dyskinesias, psychosis) may have anti-NMDAR encephalitis

Absence of system xc⁻ on immune cells invading the central nervous system alleviates experimental autoimmune encephalitis

Background: Multiple sclerosis (MS) is an autoimmune demyelinating disease that affects the central nervous system (CNS), leading to neurodegeneration and chronic disability. Accumulating evidence points to a key role for neuroinflammation, oxidative stress, and excitotoxicity in this degenerative process. System x(c)- or the cystine/glutamate antiporter could tie these pathological mechanisms together: its activity is enhanced by reactive oxygen species and inflammatory stimuli, and its enhancement might lead to the release of toxic amounts of glutamate, thereby triggering excitotoxicity and neurodegeneration. Methods: Semi-quantitative Western blotting served to study protein expression of xCT, the specific subunit of system x(c)-, as well as of regulators of xCT transcription, in the normal appearing white matter (NAWM) of MS patients and in the CNS and spleen of mice exposed to experimental autoimmune encephalomyelitis (EAE), an accepted mouse model of MS. We next compared the clinical course of the EAE disease, the extent of demyelination, the infiltration of immune cells and microglial activation in xCT-knockout (xCT(-/-)) mice and irradiated mice reconstituted in xCT(-/-) bone marrow (BM), to their proper wild type (xCT(+/+)) controls. Results: xCT protein expression levels were upregulated in the NAWM of MS patients and in the brain, spinal cord, and spleen of EAE mice. The pathways involved in this upregulation in NAWM of MS patients remain unresolved. Compared to xCT(+/+) mice, xCT(-/-) mice were equally susceptible to EAE, whereas mice transplanted with xCT(-/-) BM, and as such only exhibiting loss of xCT in their immune cells, were less susceptible to EAE. In none of the above-described conditions, demyelination, microglial activation, or infiltration of immune cells were affected. Conclusions: Our findings demonstrate enhancement of xCT protein expression in MS pathology and suggest that system x(c)- on immune cells invading the CNS participates to EAE. Since a total loss of system x(c)- had no net beneficial effects, these results have important implications for targeting system x(c)- for treatment of MS

Induction of Biogenic Magnetization and Redox Control by a Component of the Target of Rapamycin Complex 1 Signaling Pathway

Most organisms are simply diamagnetic, while magnetotactic bacteria and migratory animals are among organisms that exploit magnetism. Biogenic magnetization not only is of fundamental interest, but also has industrial potential. However, the key factor(s) that enable biogenic magnetization in coordination with other cellular functions and metabolism remain unknown. To address the requirements for induction and the application of synthetic bio-magnetism, we explored the creation of magnetism in a simple model organism. Cell magnetization was first observed by attraction towards a magnet when normally diamagnetic yeast Saccharomyces cerevisiae were grown with ferric citrate. The magnetization was further enhanced by genetic modification of iron homeostasis and introduction of ferritin. The acquired magnetizable properties enabled the cells to be attracted to a magnet, and be trapped by a magnetic column. Superconducting quantum interference device (SQUID) magnetometry confirmed and quantitatively characterized the acquired paramagnetism. Electron microscopy and energy-dispersive X-ray spectroscopy showed electron-dense iron-containing aggregates within the magnetized cells. Magnetization-based screening of gene knockouts identified Tco89p, a component of TORC1 (Target of rapamycin complex 1), as important for magnetization; loss of TCO89 and treatment with rapamycin reduced magnetization in a TCO89-dependent manner. The TCO89 expression level positively correlated with magnetization, enabling inducible magnetization. Several carbon metabolism genes were also shown to affect magnetization. Redox mediators indicated that TCO89 alters the intracellular redox to an oxidized state in a dose-dependent manner. Taken together, we demonstrated that synthetic induction of magnetization is possible and that the key factors are local redox control through carbon metabolism and iron supply

Bean Golden Mosaic: Research Advances

El frijol (Phaseolus vulgaris L.) es una de las fuentes de proteina (15-35%) y calorías (ca. 340 caI./100 gr) más importantes en la América Latina. En esta región, centro de origen de esta especie, se producen más de cuatro millones de toneladas de frijol al año, lo cual equivale al 88% de la semilla de frijol producida en las regiones tropicales del mundo. Brasil, el mayor productor de frijol del mundo, posee un consumo per capita de cerca de 20 kg/año. En America Central, el frijol es igualmente importante, siendo consumido en la mayoría de los países centroamericanos hasta tres veces por día. Proporcionalmente, en la America Central se cultiva el doble del área que en Brasil, relativo a sus extensiones territoriales. El frijol es también producido en islas del Caribe, tales como Cuba (ca. 26.000 TM), Haití (56.000 TM) y República Dominicana (55.000 TM) según datos de 1990 (CIAT). México, el segundo productor de frijol en la America Latina, consume aproximadamente 1.2 millones de toneladas métricas de frijol al año. A pesar de que México cultiva cerca de 1.800.000 hectáreas de frijol, la demanda interna no es satisfecha en algunos años dado la baja productividad del cultivo. Esta baja productividad relativa del frijol, no solo en México sino también en el resto de la América Latina (700 kg/ha vs. 1.600 kg/ha en los Estados Unidos), es una consecuencia de los múltiples problemas bióticos y abióticos que inciden en el cultivo, en el trópico Americano. Es precisamente en las regiones productoras de frijol situadas en climas cálidos, de altitud baja a intermedia (0-1200 m.s.n.m), donde el mosaico dorado del frijol alcanza su mayor incidencia.The common bean (Phaseolus vulgaris L.) is an important source of protein and calories in Latin America. In this region, the center of origin of this legume species, over 4 million tons of dry beans are produced per year. Nevertheless, many Latin American countries, including two of the largest producers of beans in the world, Brazil and Mexico, have to import beans to meet internal demand. This shortage of beans is related to the low productivity of this crop in Latin America (700 kg /ha vs. 1,600 kg/ ha average in the USA). The low productivity in the main bean production regions of tropical America is associated to the incidence of several biotic and abiotic constraints. Among the biotic constraints, bean golden mosaic virus is undoubtedly the main bean production problem in the lowland tropics, particularly, during the dry seasons of the year.Programa Cooperativo Regional de Frijol para Centroamérica, México y el Caribe (PROFRIJOL)Cooperación Suiza para el Desarrollo (COSUDE)Centro Internacional de Agricultura Tropical (CIAT)UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Estación Experimental Agrícola Fabio Baudrit Moreno (EEAFBM

Shattered pellet injection experiments at JET in support of the ITER disruption mitigation system design

A series of experiments have been executed at JET to assess the efficacy of the newly installed shattered pellet injection (SPI) system in mitigating the effects of disruptions. Issues, important for the ITER disruption mitigation system, such as thermal load mitigation, avoidance of runaway electron (RE) formation, radiation asymmetries during thermal quench mitigation, electromagnetic load control and RE energy dissipation have been addressed over a large parameter range. The efficiency of the mitigation has been examined for the various SPI injection strategies. The paper summarises the results from these JET SPI experiments and discusses their implications for the ITER disruption mitigation scheme

New H-mode regimes with small ELMs and high thermal confinement in the Joint European Torus

New H-mode regimes with high confinement, low core impurity accumulation, and small edge-localized mode perturbations have been obtained in magnetically confined plasmas at the Joint European Torus tokamak. Such regimes are achieved by means of optimized particle fueling conditions at high input power, current, and magnetic field, which lead to a self-organized state with a strong increase in rotation and ion temperature and a decrease in the edge density. An interplay between core and edge plasma regions leads to reduced turbulence levels and outward impurity convection. These results pave the way to an attractive alternative to the standard plasmas considered for fusion energy generation in a tokamak with a metallic wall environment such as the ones expected in ITER.&amp; nbsp;Published under an exclusive license by AIP Publishing