Loop representation of charged particles interacting with Maxwell and Chern-Simons fields

The loop representation formulation of non-relativistic particles coupled with abelian gauge fields is studied. Both Maxwell and Chern-Simons interactions are separately considered. It is found that the loop-space formulations of these models share significant similarities, although in the Chern-Simons case there exists an unitary transformation that allows to remove the degrees of freedom associated with the paths. The existence of this transformation, which allows to make contact with the anyonic interpretation of the model, is subjected to the fact that the charge of the particles be quantized. On the other hand, in the Maxwell case, we find that charge quantization is necessary in order to the geometric representation be consistent.Comment: 6 pages, improved versio

A Geometric Approach to Massive p-form Duality

Massive theories of abelian p-forms are quantized in a generalized path-representation that leads to a description of the phase space in terms of a pair of dual non-local operators analogous to the Wilson Loop and the 't Hooft disorder operators. Special atention is devoted to the study of the duality between the Topologically Massive and the Self-Dual models in 2+1 dimensions. It is shown that these models share a geometric representation in which just one non local operator suffices to describe the observables.Comment: 26 pages, LaTeX. The discussion about the equivalence between the Proca model and two seldual models, with opposite spins, was eliminated. Typos correcte

Maxwell Chern Simons Theory in a Geometric Representation

We quantize the Maxwell Chern Simons theory in a geometric representation that generalizes the Abelian Loop Representation of Maxwell theory. We find that in the physical sector, the model can be seen as the theory of a massles scalar field with a topological interaction that enforces the wave functional to be multivalued. This feature allows to relate the Maxwell Chern Simons theory with the quantum mechanics of particles interacting through a Chern Simons fieldComment: 12 pages, LaTe

Análisis biostático de las tensiones actuantes en el dentario del oso andino (Tremarctos Ornatus) durante la mordedura

This study was intended to contribute to the biological and biostatical knowledge of the Andean bear, the fourth bear largest in the world and the largest carnivore living in the Neotropics. Tensions were high, asking the tooth during, their reactions and behavior cutting efforts and maximum flexor moments, along the jaw vain. This will be analyzed 3 complete skulls and a jaw from wild animals of Bolivia, using 9 skull measurements as descriptors. The maximum bite requests were considered in the canines (c) and second upper molars (m2). It also determined the intensity of them, by calculating of the tensions reached higher in these sections, depending on the Fracture strength (?R = 0.50 kg/mm2). The final system, responds to two portions of a hiperestatical structure and its resolution is achieved through the Moment Distribution Method by Cross. It was found that the maximum bite force in the male is 246.90 kg being 1.34 times higher in the molars. The female, have reached a bite of 184.96 kg and a milling intensity of 285.75 kg. The increased intensity in over 80 kg in the molars on the canines is directly proportional to the great development of the temporalis-masseteric muscle, as the structural design of bone in the masseteric fossa and the width of face at molar. These biostatics characters reflect the design expertise craniodental of the species to withstand major stresses, product of crushing and grinding tough fibrous plants in general and training unique to the male predation. What it enables the Andean bear to have a varied diet and opportunistic in its ecological niche, adaptable to food resources that the environment offered.El presente estudio tuvo la finalidad de contribuir al conocimiento biológico y biostático del oso andino (Tremarctos ornatus), el cuarto úrsido de mayor tamaño del mundo y el carnívoro más grande viviente del Neotrópico. Se obtuvieron las tensiones máximas que solicitan al dentario durante la mordedura, sus reacciones y comportamiento a los esfuerzos de corte y momentos flexores máximos, a lo largo del vano mandibular. Para ello, se analizaron 3 cráneos completos y un dentario provenientes de animales silvestres de Bolivia, utilizando 9 medidas craneanas como descriptores. Las cargas máximas de mordedura se consideraron en los caninos (c) y segundos molares superiores (m2). Se determinaron además la intensidad de las mismas, mediante el cálculo de las tensiones más elevadas alcanzadas en dichas secciones, en función de la Tensión de Rotura (?R = 0,50 kg/mm2). El sistema final propuesto, responde a dos tramos de una estructura hiperestática y su resolución se efectúo mediante el Método de Aproximaciones Sucesivas de Cross. Se encontró que la fuerza máxima de mordedura en el macho es de 246,90 kg siendo 1,34 veces mayor aproximadamente, en los molares. La hembra llega a tener una mordida de 184,96 kg y una intensidad de molienda de 285, 75 kg. El aumento de la intensidad, en más de 80 kg en los molares respecto a los caninos, es directamente proporcional al gran desarrollo del músculo temporal-masetérico; como el diseño estructural óseo en la fosa homónima y la anchura del rostro a nivel molar. Estos caracteres biostáticos denotan la especialización del diseño craneodentario de la especie para soportar grandes cargas; producto de triturar y moler vegetales fibrosos duros en general, y una capacitación singular del macho para la depredación. Lo que lo posibilita al oso andino a tener una dieta variada y oportunista en su nicho ecológico, adaptable a los recursos alimenticios que el medio le ofrezca

Interacting Particles and Strings in Path and Surface Representations

Non-relativistic charged particles and strings coupled with abelian gauge fields are quantized in a geometric representation that generalizes the Loop Representation. We consider three models: the string in self-interaction through a Kalb-Ramond field in four dimensions, the topological interaction of two particles due to a BF term in 2+1 dimensions, and the string-particle interaction mediated by a BF term in 3+1 dimensions. In the first case one finds that a consistent "surface-representation" can be built provided that the coupling constant is quantized. The geometrical setting that arises corresponds to a generalized version of the Faraday's lines picture: quantum states are labeled by the shape of the string, from which emanate "Faraday`s surfaces". In the other models, the topological interaction can also be described by geometrical means. It is shown that the open-path (or open-surface) dependence carried by the wave functional in these models can be eliminated through an unitary transformation, except by a remaining dependence on the boundary of the path (or surface). These feature is closely related to the presence of anomalous statistics in the 2+1 model, and to a generalized "anyonic behavior" of the string in the other case.Comment: RevTeX 4, 28 page

The space of signed points and the Self Dual Model

We study a generalization of the group of loops based on sets of signed points, instead of paths or loops. This geometrical setting incorporates the kinematical constraints of the Sigma Model, inasmuch as the the group of loops does with the Bianchi identities of Yang-Mills theories. We employ an Abelian version of this construction to quantize the Self-Dual Model, which allows us to relate this theory with that of a massless scalar field obeying non-trivial boundary conditions.Comment: (9 pages

Fuerza de mordedura y estrés mandibular en el jaguar (Panthera onca) durante la depredación de pecaríes (Artiodactyla: Tayassuidae) mediante la fractura de sus cráneos

One of the most effective ways of the jaguar’s predation (Panthera onca) is the application of bite force at the neurocranium of peccaries, one of its main natural preys, causing highly compressivestress that becomes fracture with its back a quick killing. In the present study were analyzed by the method of dry skull, 15 adult jaguar’s skulls moreover completing craniometrical measures withreported data in the literature belonging to different subspecies or phenotypes of this species’ distributional range, to obtain its maximum bite’s force canines and carnassials moreover of the cutting efforts and maximum flexor moments along the jaw. The resolution of these variables in a hiperestaticity structureis achieved through the Moment Distribution Method by Cross. After correlated the maximum bite forces of the jaguar and its action in the cross section of the neurocranium of Pecari tajacu, Tayassupecari and Catagonus wagneri by Cremona method to obtain the internal stress for before skull fracture. It was found that jaguar’s maximum canine bite force is of 681.56 Newton and in the carnassials line is still 3 times most compressive. These forces are sufficiently high to cause fracture of a rigid structure asis the neurocranium’s triangular section of the peccaries. Moreover the jaguar’s robust canines resist the bending forces applied by struggling prey and a wider muzzle helps to stabilize grip and distribute bite forces more evenly during the killing bite.Una de las formas de depredación más efectivas del jaguar (Panthera onca) consiste en la aplicación de su fuerza de mordedura en el neurocráneo de los pecaríes, una de sus principales presas naturales, provocándole un estrés altamente compresivo que deviene en la posterior fractura del cráneo con una muerte rápida. En el presente estudio se analizaron mediante el método del cráneo seco, 15 cráneos completos y medidas craneométricas reportadas en la literatura, para jaguares adultos pertenecientes a diferentes subespecies o fenotipos del rango distributivo de P. onca. Afín de obtener sus fuerzas de mordedura canina y carnasial, esfuerzos de corte y momentos flexores máximos a lo largo del vano mandibular.La obtención de estas variables, en una estructura hiperestática se efectúo mediante el Método de Aproximaciones Sucesivas de Cross. Después se correlacionaron las fuerzas de mordedura máximas del jaguar y su acción en la sección transversal del neurocráneo de ecari tajacu, Tayassu pecari y Catagonus wagneri mediante el método de Cremona, para obtener las tensiones internas que someten al cráneo de los pecaríes previa fractura. Se encontró que la fuerza máxima de mordedura canina del jaguar es de 681,56 Newton siendo 3 veces más compresiva en los carnasiales. Estas son lo suficientementealtas, como para provocar la rotura de una estructura rígida, como la sección triangular del neurocráneo en los pecaríes. Además los caninos robustos del jaguar resisten las fuerzas de pandeo aplicadas sobre los mismos durante la lucha con la presa, y una boca más amplia ayuda a una mejor adherencia y distribución uniforme de las fuerzas de mordedura, durante la mordida mortal

Potencial efecto fungicida de extractos vegetales en el desarrollo in vitro del hongo Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. y de la antracnosis en frutos de mango | Potential fungicidal effect of plant extracts on in vitro development of Colletotrichum gloeosporioides and on anthracnose of mango

Se determinó el efecto de la aplicación de los extractos etanólicos (EE) de hojas de Azadirachta indica (‘nim’); Phyllanthus niruri (‘flor escondida’); Calotropis procera (‘algodón de seda’); Lippia origanoides (‘orégano silvestre’); Gliricidiasepium (‘mata ratón’) y Heliotropium indicum (‘rabo de alacrán’), colectadas en el estado Lara, Venezuela, en el control de la antracnosis ocasionada por el hongo Colletotrichum gloesporioides en frutos de mango (Mangifera indica). El extracto se obtuvo por presión reducida y se determinaron los grupos de metabolitos secundarios (MS) presentes en ellos. El patógeno se hizo crecer en el medio nutritivo PDA. La determinación del efecto de los EE a una concentración de 2,5% se hizo bajo tres métodos de aplicación in vitro. Frutos de mango fisiológicamente maduros fueron tratados con los extractos al2,5 % y luego inoculados con el hongo. Se encontró que las plantas diferían en los grupos de MS. El EE del L. origanoides y H. indicum, homogenizados en el medio, ocasionaron la mayor disminución del crecimiento micelial de C.gloeosporioides. Los EE de L. origanoides y G. sepium fueron los mejores tratamientos de postcosecha, ya que indujeron el 37 y 33 % menos de la enfermedad en los frutos de mango, respectivamente. Los resultados indican el potencial de los extractos para el manejo de la antracnosis del mango en postcosecha.Palabras clave: Postcosecha, metabolitos secundarios, Mangifera indica LABSTRACTThe effect of applying ethanolic extracts (EE) of leaves of Azadirachta indica (‘nim’); Phyllanthus niruri (‘flor escondida’); Calotropis procera (‘algodón de seda’); Lippia origanoides (‘orégano silvestre’); Gliricidia sepium (‘mataratón’) and Heliotropium indicum (‘rabo de alacrán’) collected in the state of Lara, Venezuela, on the control of mango anthracnose caused by Colletotrichum gloeosporioides was evaluated The plant extract was obtained by reduced pressure and the secondary metabolites (MS) were determined. The microorganism was grown on PDA media. The effect of the EEat 2.5 % concentration was evaluated following three methods of application. Mango fruits at the adequate ripening stage were treated with the concentration of 2.5 % and then inoculated with the fungus. Differences were found in the plants extracts with regard to the MS present. L. origanoides and H. indicum EE, homogenized in the medium caused the highest inhibition of C. gloeosporioides mycelium. The EE of L. origanoides and G. sepium were the best postharvest treatment since they induced 37 and 33 % less disease in mango fruits. Results indicate the potential of plant extracts to handle mango anthracnose in postharvest.Key words: Postharvest, secondary metabolites, Mangifera indica L

Control of Flowering in Strawberries

Strawberries (Fragaria sp.) are small perennial plants capable of both sexual reproduction through seeds and clonal reproduction via runners. Because vegetative and generative developmental programs are tightly connected, the control of flowering is presented here in the context of the yearly growth cycle. The rosette crown of strawberry consists of a stem with short internodes produced from the apical meristem. Each node harbors one trifoliate leaf and an axillary bud. The fate of axillary buds is dictated by environmental conditions; high temperatures and long days (LDs) promote axillary bud development into runners, whereas cool temperature and short days (SDs) favor the formation of branch crowns. SDs and cool temperature also promote flowering; under these conditions, the main shoot apical meristem is converted into a terminal inflorescence, and vegetative growth is continued from the uppermost axillary branch crown. The environmental factors that regulate vegetative and generative development in strawberries have been reasonably well characterized and are reviewed in the first two chapters. The genetic basis of the physiological responses in strawberries is much less clear. To provide a point of reference for the flowering pathways described in strawberries so far, a short review on the molecular mechanisms controlling flowering in the model plant Arabidopsis is given. The last two chapters will then describe the current knowledge on the molecular mechanisms controlling the physiological responses in strawberries.Peer reviewe

Additive QTLs on three chromosomes control flowering time in woodland strawberry (Fragaria vesca L.)

Flowering time is an important trait that affects survival, reproduction and yield in both wild and cultivated plants. Therefore, many studies have focused on the identification of flowering time quantitative trait locus (QTLs) in different crops, and molecular control of this trait has been extensively investigated in model species. Here we report the mapping of QTLs for flowering time and vegetative traits in a large woodland strawberry mapping population that was phenotyped both under field conditions and in a greenhouse after flower induction in the field. The greenhouse experiment revealed additive QTLs in three linkage groups (LG), two on both LG4 and LG7, and one on LG6 that explain about half of the flowering time variance in the population. Three of the QTLs were newly identified in this study, and one co-localized with the previously characterized FvTFL1 gene. An additional strong QTL corresponding to previously mapped PFRU was detected in both field and greenhouse experiments indicating that gene(s) in this locus can control the timing of flowering in different environments in addition to the duration of flowering and axillary bud differentiation to runners and branch crowns. Several putative flowering time genes were identified in these QTL regions that await functional validation. Our results indicate that a few major QTLs may control flowering time and axillary bud differentiation in strawberries. We suggest that the identification of causal genes in the diploid strawberry may enable fine tuning of flowering time and vegetative growth in the closely related octoploid cultivated strawberry.Peer reviewe