Payment for urban water feasibility and the urban dispersed growth in Northern Mexico (a proposal)

This work proposes to analyze the collection of urban water feasibility payments as a mechanism to control the urban dispersed growth in northern Mexico. This perspective tries to go beyond achieving the financial sustainability of the urban infrastructure and proposes to incorporate elements of urban sustainability. The essay analyzes two cases: the city of Saltillo Coahuila and the Nuevo León state.urban water, water feasibility payments, northern Mexico

QCD and Intrinsic Heavy Quark Predictions for Leading Charm and Beauty Hadroproduction

Recent experiments at Fermilab and CERN have observed a strong asymmetry between the hadroproduction cross sections of leading $D$ mesons, containing projectile valence quarks, and nonleading charmed mesons, without projectile valence quarks. The observed correlations of the $\pi^{\pm} N \to D^\pm X$ cross section with the projectile charge violates the usual assumption that heavy quark jet fragmentation factorizes. We examine the asymmetry between leading and nonleading charm production as a function of $x_f$ and $p_T^2$ assuming a two-component model combining leading-twist fusion subprocesses and charm production from intrinsic heavy quark Fock states. We predict a sizable asymmetry at low $p_T^2$ and high $x_f$ from coalescence of the charm quarks with the comoving spectator quarks of the projectile. An intrinsic $c \overline c$ production cross section of 0.5 $\mu$b is sufficient to explain both the magnitude and kinematic dependence of the asymmetry. In contrast, the charm jet hadronization mechanisms contained in PYTHIA predict a sizeable leading charm asymmetry even at low $x_F.$ The two-component model is extended to predict the asymmetry in $B$ meson production in proton-proton and pion-proton interactions.Comment: 16 pages LaTeX with 6 postscript figures available upon request, LBL-35380, SLAC-PUB-646

El cobro por una factibilidad sostenible del agua y el crecimiento urbano disperso en el norte de México

This work proposes to analyze the collection of urban water feasibility payments as a mechanism to control the urban dispersed growth in northern Mexico. This perspective tries to go beyond achieving the financial sustainability of the urban infrastructure and proposes to incorporate elements of urban sustainability. The essay analyzes two cases: the city of Saltillo Coahuila and the Nuevo León state

El cobro por una factibilidad sostenible del agua y el crecimiento urbano disperso en el norte de México

This work proposes to analyze the collection of urban water feasibility payments as a mechanism to control the urban dispersed growth in northern Mexico. This perspective tries to go beyond achieving the financial sustainability of the urban infrastructure and proposes to incorporate elements of urban sustainability. The essay analyzes two cases: the city of Saltillo Coahuila and the Nuevo León state

Study of reproductive floral traits and pod dehiscence in legumes

Las leguminosas desempeñan un papel central en la agricultura y contribuyen a una producción más sostenible al romper ciclos de enfermedades y plagas y reducir la dependencia de fertilizantes químicos, gracias a su capacidad única de fijar el nitrógeno atmosférico. Dentro de este grupo encontramos cultivos tradicionales como guisante, judía, lenteja, garbanzo y habas. Éstas últimas son la tercera y quinta leguminosa grano más cultivadas en el mundo, respectivamente. En la búsqueda de mejores características, el ser humano ha ido seleccionando plantas mediante la mejora convencional, un proceso largo y costoso. Actualmente el desarrollo de potentes herramientas genómicas permite buscar e identificar genes implicados en el control de caracteres de interés para su uso en mejora asistida por marcadores (en inglés, MAS). En los capítulos I y II se ha realizado un exhaustivo estudio fenotípico de la dehiscencia de la vaina en garbanzos y habas. Empleamos la estrategia de genes candidatos de especies modelo y leguminosas relacionadas para identificar ortólogos y saturar los mapas genéticos de ambas especies. Finalmente, los datos fenotípicos obtenidos se emplearon para realizar un análisis de QTLs que reveló la herencia poligénica o cuantitativa del carácter y su localización en los respectivos cromosomas. Ambos trabajos fueron pioneros, mostrando la conservación de genes entre distintas leguminosas y apuntando hacia mecanismos y rutas homólogas en el control de la dehiscencia. Los análisis histológicos evidenciaron una mayor complejidad en el patrón de lignificación de las vainas de habas. En el capítulo III, aplicamos la estrategia de genes candidatos para identificar QTLs y genes ortólogos reguladores de la fecha de floración en habas. Se trata de un carácter de gran interés ya que permite optimizar el rendimiento de un cultivo evitando la exposición a estreses. Se han detectado varios QTLs sinténicos con otras leguminosas, mostrando el alto grado de conservación de la ruta reguladora del carácter, siendo el más importante el situado en el cromosoma V, donde se agrupan distintos genes implicados en la floración. Los resultados apuntan, además, a una posible regulación epigenética del carácter. Por último, en el capítulo IV, se ha realizado un meticuloso estudio de la genética del carácter autofertilidad, importante para el éxito reproductivo de un cultivo dado el descenso de polinizadores por el uso abusivo de insecticidas o la falta de sincronía en las visitas por el calentamiento global. Este carácter se define como la capacidad de las flores para autofecundarse en ausencia de polinizadores o de una perturbación mecánica. En nuestro estudio se ha diseccionado el carácter en diferentes características de la flor y el polen, asociados al cuajado de vainas y semillas. Los resultados mostraron diferencias en las medidas morfológicas y de cantidad de polen entre los parentales utilizados y una clara asociación de la cantidad de polen viable y el ángulo estilo-ovario con la autofertilidad. Del mismo modo, se encontró un gran número de QTLs co-localizando en seis regiones genómicas, las cuales se encuentran flanqueadas por genes funcionalmente relacionados con las medidas de cantidad de polen y cuajado de vainas y semillas.Legumes play a central role in agriculture and contribute to a more sustainable production by reducing dependence on chemical fertilizers, thanks to their unique ability to fix atmospheric nitrogen and breaking cycles of diseases and pests. Within this group we find traditional crops such as peas, beans, lentils, chickpeas and beans. The latter two are the third and fifth most cultivated grain legumes in the world. Looking for better characteristics, humans have been selecting plants through conventional improvement, a long and expensive process. Currently, the development of powerful genomic tools makes it possible to search for genes involved in the control of traits of interest and use them in markerassisted improvement (MAS) approaches. Chapters I and II describe an exhaustive phenotypic study of pod dehiscence in chickpeas and faba bean. We used the candidate gene strategy from model and related legume species to identify orthologs and saturate the genetic maps in both crops. Finally, the phenotypic data obtained were used to perform a QTL analysis that revealed the polygenic or quantitative inheritance of the trait and the QTLs location on their respective chromosomes. These pioneering studies revealed the conservation of genes between different legumes and pointed towards homologous mechanisms and routes in the control of the dehiscence. The histological analysis showed a more complex pattern in the lignification of the faba bean pods similar to Brassica species and contrary to bean and soybean. In Chapter III, we apply the candidate gene strategy to identify QTLs and orthologous genes underlying flowering date in faba beans. It is a character of great interest since it allows optimizing the yield of a crop, avoiding the exposure to possible stresses. Several QTLs syntenic with other legume crops were detected, showing the high degree of conservation of the genetic regulatory pathway in this trait. The most important QTL was located on chromosome V, where different genes involved in flowering are grouped. The results also point to a possible epigenetic regulation of the character. Finally, in chapter IV, a meticulous study of the genetics of self-fertility was carried out. Selffertility is a key trait for the reproductive success of a crop given the decrease in pollinators for the abusive use of insecticides or the lack of synchrony with the insect visits due to global warming. This character is defined as the ability of flowers to self-pollinate in the absence of pollinators or mechanical disturbance. In our study, the character has been dissected into different flower and pollen characteristics associated with the set of pods and seeds. The results showed differences in the morphological and pollen quantity measurements between the parents and a clear association of the amount of viable pollen and the style-ovary angle with self-fertility. Similarly, a large number of QTLs were found co-locating in six genomic regions. All these QTLs were flanked by genes functionally related to measurements of pollen quantity and pod and seed set

Heavy-Quark Correlations in Direct Photon-Photon Collisions

In two-photon collisions at LEP2 and a future $e^+e^-$ linear collider heavy quarks (mainly charm) will be pair-produced rather copiously. The production via direct and resolved photons can be distinguished experimentally via a remnant-jet tag. We study correlations of the heavy quarks at next-to-leading order in QCD in the direct channel, which is free from phenomenological parton densities in the photon. These correlations are therefore directly calculable in perturbative QCD and provide a stringent test of the production mechanism.Comment: 10 pages, LaTeX, epsfig, 5 figures appended as uuencoded file (hardcopy can be obtained upon request from [email protected] or [email protected]

Transverse momentum spectra of identified particles in high energy collisions with statistical hadronisation model

A detailed analysis is performed of transverse momentum spectra of several identified hadrons in high energy collisions within the framework of the statistical model of hadronisation. The effect of the decay chain following hadron generation is accurately taken into account. The considered centre-of-mass energies range from ~ 10 to 30 GeV in hadronic collisions (pi+ p, pp and Kp) and from ~ 15 to 45 GeV in e+e- collisions. A clear consistency is found between the temperature parameter extracted from the present analysis and that obtained from fits to average hadron multiplicities in the same collision systems. This finding indicates that in the hadronisation, the production of different particle species and their momentum spectra are two closely related phenomenons governed by one parameter.Comment: Talk given by F. Becattini in "Correlations and Fluctuations 2000", 12 pp., 11 figure

Hidrogenación selectiva de fenilacetileno en Pd/Al₂O₃ efecto de la adición de Pt, del tamaño de partícula y envenenamiento

Se estudio la hidrogenaci6n selectiva de fenilacetileno en catalizadores de Pd/n1203, el efecto de adicidn de Pt, el tamatio de particula en la actividad y 8el.ctivid.d tanto en catalizadores soportados Alzo3 como sio2 y por Ultimo el envenenamiento con (UB,) y tiofeno. La dirprsibn metalica (%O) se determid por gravimotrla utilizando el m4todo de titulaci6n hidr6geno-oxlgeno. Los dil[metros pramedio de partlcula fueron determinados por Kicroscopla Electr6nica en un equipo de transmisi6n Jeol 1OOCX. La deterainaci6n de la actividad catalltica se llevo a cabo en un reactor diferencial a baja conversibn (45%) en la mayoria de los casos. Las condiciones de reacci6n fueron la8 siguientes: Presibn parcial del fenilacetileno de 6.6 torr, preai6n parcial de hidr4geno 760 torr, masa del catalizador 0.050-0.015 gr. y temperatura de reaccibn 45%. xn base a los resultados concluimos que: a) la actividad del Pd es mayor que la del Pt en catalizadores soportados en &120,, mientras que la selectividad hacia estireno es menor en Pd que en Pt, probablemente a la menor formaci6n de reeiduos carbonaceos en la superficie, e1 cual e. mayor en Pts b) m los catalizadores Pt-Pd/Alz03 re observo un efecto de segregacibn del Pt a contenidos 2 35% de Pt; c) La actividad en los catalizadores Pt/nlp3, Pd/A1203 y Pd/SiOz no se ven afectados por el tanmilo de partlcula, ni se observa efecto de soporte en la Selectividad del Pd en hluIC3 6 Si02; d) €lay un aumento de la selectividad en funcidn del timpo, debido a que se depositan especies oligom4ricas; e) La selectividad inicial en catalizadore. enmnenados de baja dispersi6n es menor que en catalizadores M envenenados; f) Los catalitadores envenenados con

The Rho-Meson as a Collective Excitation

A model of the rho-meson as a collective excitation of $q\bar{q}$ pairs in a system that obeys the modified Nambu--Jona-Lasinio Lagrangian is proposed. The rho emerges as a dormant Goldstone boson. The origin of the rho-meson mass is understood as a result of spontaneous chiral symmetry breaking. The low-energy dynamics of rho, pi, omega and gamma is consistently described in this new framework. The model accounts for the origin of the celebrated Kawarabayashi--Suzuki--Riazuddin--Fayyazuddin relation.Comment: 8 pages, plain LaTe