Correlated two-particle scattering on finite cavities

The correlated two-particle problem is solved analytically in the presence of a finite cavity. The method is demonstrated here in terms of exactly solvable models for both the cavity as well as the two-particle correlation where the two-particle potential is chosen in separable form. The two-particle phase shift is calculated and compared to the single-particle one. The two-particle bound state behavior is discussed and the influence of the cavity on the binding properties is calculated.Comment: Derivation shortened and corrected, 14 pages 10 figure

Nuevas series del comercio exterior de México, 1870-1929

Editada en la Fundación Empresa PúblicaEl artículo se ocupa de reconstruir los valores anuales del comercio exterior de México en el período 1870-1929, la llamada era del capitalismo liberal. Además de las estadísticas oficiales de este país, utiliza las de sus principales socios comerciales: Estados Unidos, Gran Bretaña, Francia y Alemania. Evalúa la calidad y consistencia de las fuentes mexicanas y aplica criterios explícitos para rectificar las cifras oficiales y cubrir las brechas en la información disponible. Asimismo, propone una reagrupación de los valores del comercio que permite distinguir entre el intercambio de mercancías y los flujos de metálico. Como resultado, ofrece series completas del comercio de mercancías y de las transferencias de dinero en especie, así como un cálculo anual de la balanza comercial para todo el período.This paper provides a reconstruction of the yearly values of Mexico's foreign trade within the period 1870-1929, the era of liberal capitalism. It uses the Mexican official statistics as well as those published by Mexico's main trading partners: the United States, Great Britain, France, and Germany. The article assesses the quality and consistency of the Mexican sources and applies explicit criteria to rectify the official figures and to fill the gaps in the available information. It also proposes a new breakdown of trade values, which allows distinguishing between commodity trade and specie movements. As a result, the article provides with complete annual series of commodity trade and specie flows, as well as a yearly estimate of the trade balance throughout the period.Publicad

Connexin-43 prevents hematopoietic stem cell senescence through transfer of reactive oxygen species to bone marrow stromal cells

Hematopoietic stem cell (HSC) aging has become a concern in chemotherapy of older patients. Humoral and paracrine signals from the bone marrow (BM) hematopoietic microenvironment (HM) control HSC activity during regenerative hematopoiesis. Connexin-43 (Cx43), a connexin constituent of gap junctions (GJs) is expressed in HSCs, down-regulated during differentiation, and postulated to be a self-renewal gene. Our studies, however, reveal that hematopoietic-specific Cx43 deficiency does not result in significant long-term competitive repopulation deficiency. Instead, hematopoietic Cx43 (H-Cx43) deficiency delays hematopoietic recovery after myeloablation with 5-fluorouracil (5-FU). 5-FU-treated H-Cx43-deficient HSC and progenitors (HSC/P) cells display decreased survival and fail to enter the cell cycle to proliferate. Cell cycle quiescence is associated with down-regulation of cyclin D1, up-regulation of the cyclin-dependent kinase inhibitors, p21cip1. and p16INK4a, and Forkhead transcriptional factor 1 (Foxo1), and activation of p38 mitogen-activated protein kinase (MAPK), indicating that H-Cx43-deficient HSCs are prone to senescence. The mechanism of increased senescence in H-Cx43-deficient HSC/P cells depends on their inability to transfer reactive oxygen species (ROS) to the HM, leading to accumulation of ROS within HSCs. In vivo antioxidant administration prevents the defective hematopoietic regeneration, as well as exogenous expression of Cx43 in HSC/P cells. Furthermore, ROS transfer from HSC/P cells to BM stromal cells is also rescued by reexpression of Cx43 in HSC/P. Finally, the deficiency of Cx43 in the HM phenocopies the hematopoietic defect in vivo. These results indicate that Cx43 exerts a protective role and regulates the HSC/P ROS content through ROS transfer to the HM, resulting in HSC protection during stress hematopoietic regeneration

A Novel Fixture Development to Characterize Compression After Impact Damage of Unidirectional Thermoplastic Composite Laminates

Impact testing of unidirectional thermoplastic composite materials is a challenge due to the Mode I shear of the primary tows on the impact side. Thermoplastic composite products manufactured using laminate stacking are bonded together with films of polymer on both sides of oriented fiber in typically a cross-ply or quasi-isotropic stack. The resulting failure from the distortion field imposed by a hemispherical tup is debonding along the interface between layer 1 and layer 2 oriented in the layer 1 direction from impact site to edge of panel. This failure mode results when the sample is too small relative to the weave pattern and fixturing resulting in more damage than will be witnessed on a large panel. The conservative estimate of impact strength would be appropriate for designing near edges of panels. In order to characterize an effective mid-panel impact toughness with standard Compression After Impact (CAI) fixturing, samples were created with additional length of the primary tows while still being able to fit in the CAI fixturing. Impact Energy was obtained using a Drop Tower Testing Machine. Damage zones were measured using backlit photography after the impact event. Specimens were machined post impact to allow for ASTM D7137 CAI testing to be conducted

Modelling of the effect of ELMs on fuel retention at the bulk W divertor of JET

Effect of ELMs on fuel retention at the bulk W target of JET ITER-Like Wall was studied with multi-scale calculations. Plasma input parameters were taken from ELMy H-mode plasma experiment. The energetic intra-ELM fuel particles get implanted and create near-surface defects up to depths of few tens of nm, which act as the main fuel trapping sites during ELMs. Clustering of implantation-induced vacancies were found to take place. The incoming flux of inter-ELM plasma particles increases the different filling levels of trapped fuel in defects. The temperature increase of the W target during the pulse increases the fuel detrapping rate. The inter-ELM fuel particle flux refills the partially emptied trapping sites and fills new sites. This leads to a competing effect on the retention and release rates of the implanted particles. At high temperatures the main retention appeared in larger vacancy clusters due to increased clustering rate

A Novel Keratocan Mutation Causing Autosomal Recessive Cornea Plana

PURPOSE: Mutations in keratocan (KERA), a small leucine-rich proteoglycan, have recently been shown to be responsible for cases of autosomal recessive cornea plana (CNA2). A consanguineous pedigree in which cornea plana cosegregated with microphthalmia was investigated by linkage analysis and direct sequencing. METHODS: Linkage was sought to polymorphic microsatellite markers distributed around the CNA2 and microphthalmia loci (arCMIC, adCMIC, NNO1, and CHX10) using PCR and nondenaturing polyacrylamide gel electrophoresis before KERA was directly sequenced for mutations. RESULTS: Positive lod scores were obtained with markers encompassing the CNA2 locus, the maximum two-point lod scores of 2.18 at recombination fraction theta = 0 was obtained with markers D12S95 and D12S327. Mutation screening of KERA revealed a novel single-nucleotide substitution at codon 215, which results in the substitution of lysine for threonine at the start of a highly conserved leucine-rich repeat motif. Structural modeling predicts that the motifs are stacked into an arched beta-sheet array and that the effect of the mutation is to alter the length and position of one of these motifs. CONCLUSIONS: This report describes a novel mutation in KERA that alters a highly conserved motif and is predicted to affect the tertiary structure of the molecule. Normal corneal function is dependent on the regular spacing of collagen fibrils, and the predicted alteration of the tertiary structure of KERA is the probable mechanism of the cornea plana phenotype