Dark energy, Ricci-nonflat spaces, and the Swampland

It was recently pointed out that the existence of dark energy imposes highly restrictive constraints on effective field theories that satisfy the Swampland conjectures. We provide a critical confrontation of these constraints with the cosmological framework emerging from the Salam-Sezgin model and its string realization by Cvetic, Gibbons, and Pope. We also discuss the implication of the constraints for string model building.Comment: Matching version to be published in PL

Construction of a high anchored wall at highway EX-A1 (Spain)

Descripción de la problemática encontrada en un desmonte de la autovía EX-A1 (Navalmoral de la Mata-Frontera portuguesa). Descripción de la solución adoptada: muro anclado. Highway EX-A1, near the Spain-Portugal border, crosses a Tertiary formation of weak marly rocks that are affected by high tectonic stresses that had created a good number of failure planes within the rock. During the past geologic times, some large landslides had taken place. They are now covered by Quaternary soils. The design of high cuts in this type of rock formation is somewhat troublesome. The paper indicates one of the solutions that have been implemented to stabilize one of the main highway cuts. L’autoroute EX-A1, près de la frontière entre l’Espagne et le Portugal, traverse une formation tertiaire de roches marneuses faibles avec des contraintes tectoniques élevées qui ont provoqué de nombreuses surfaces de rupture dans la roche. Au cours des temps géologiques passés, des grands glissements ont eu lieu et ils se retrouvent maintenant couverts par des sols quaternaires. Le projet d’excavations de grande hauteur dans cette formation rocheuse est généralement problématique. L’article décrit la solution qui a été mise en oeuvre pour stabiliser un des principaux déblais de l’autoroute

Clinical and pathologic remission of pediatric ulcerative colitis with serum-derived bovine immunoglobulin added to the standard treatment regimen

Ulcerative colitis (UC) is a chronic inflammatory bowel disease that is particularly troublesome for pediatric patients, as current therapeutic options consist of biologic agents and steroids which alter the immune response and have the harmful side effect of leaving the patient more susceptible to opportunistic infections and eventual surgery. Another option for therapy exists in the form of serum-derived bovine immunoglobulin/protein isolate (SBI), the key ingredient in a medical food, EnteraGam®. The FDA has reviewed the safety of SBI and issued a no challenge letter to the generally recognized as safe (GRAS) findings for this medical food. The product also has no known food or drug interactions, no significant adverse effects, and no contraindications, save for beef allergy. SBI has been shown to induce clinical remission in adult populations and to decrease markers of inflammation in pediatric patients. Here, we present a detailed case of pediatric UC, including documentation of mucosal healing and decrease in pediatric UC activity index in a difficult to treat pediatric patient, after the addition of SBI to this patient’s treatment regimen

Van der Waals spin valves

We propose spin valves where a 2D non-magnetic conductor is intercalated between two ferromagnetic insulating layers. In this setup, the relative orientation of the magnetizations of the insulating layers can have a strong impact on the in-plane conductivity of the 2D conductor. We first show this for a graphene bilayer, described with a tight-binding model, placed between two ferromagnetic insulators. In the anti-parallel configuration, a band gap opens at the Dirac point, whereas in the parallel configuration, the graphene bilayer remains conducting. We then compute the electronic structure of graphene bilayer placed between two monolayers of the ferromagnetic insulator CrI$_3$, using density functional theory. Consistent with the model, we find that a gap opens at the Dirac point only in the antiparallel configuration.Comment: 5 pages, 4 figure

Tipos de lapiaz generados en las cercanías de Zaragoza

Se han reconocido seis tipos de lapiaz sobre los materiales mesozoicos y terciarios que afloran dentro de la zona central de la Depresión del Ebro, en las cercanias de Zaragoza. De ellos, cuatro son formas conocidas: rillenkarren, solution pits (que sufren denudación), kluftkarren y hohlkarren (formas heredadas). Los otros dos micrornodelados son tipos no descritos anteriormente: lapiaz en escalones con crestas rectas y lapiaz alveolar, no habiéndose podido determinar su génesis. Sobre los depositos yesiferos se han encontrado rillenkarren y solution pits, que son funcionales actualmente

Descripción y estudio preliminar del origen de la Depresión de Valdespartera (Zaragoza)

The central Ebro Basin was filled by evaporite (gypsum, principally) and carbonate deposits of a Neogene age. During the Quaternary age the fluvial activity caused the development of structural platforms and several nested levels of terraces and pediments. It is very frequent to find small depressions that, originally, had no connection with the drainage system. We study one of these, the Valdespartera depression, which is developed following the boundary between two different aterials, the gypsum Tertiary layers in the south and the terrace and pediment Quaternary deposits in the north. From the study of the morphological charactenstics, several factors which cooperate in its genesis can be pointed out: Structural factors (mainly he presence of fractures), the preferential erosion along the boundary between the Tertiary and Quaternary sediments, the dissolution of gypsum layers and piping processes. Wind could be an important transport agent of fine sediments, eventhough no proofs of its importance were found. The main process which generated this depression is gypsum dissolution as, the presence of alluvial dolines in the region, of small basins in the infilled valleys and a surface with an intermediate slope between the Tertiary and the bottom of the depression, indicate. Piping produces dragging of detrital materials in the conduits. These processes are favoured by fractures and the weakness of the contact between Tertiary and Quaternary materials