Improved management of key northern region weeds: diverse problems, diverse solutions

The cropping region of northern Australia has a diverse range of cropping systems and weed flora. A fallow phase is commonly required between crops to enable the accumulation of stored soil water in these farming systems dominated by reduced tillage. During the fallow phase, weed control is important and is heavily reliant on herbicides. The most commonly used herbicide has been glyphosate. As a result of over-reliance on glyphosate, there are now seven confirmed glyphosate-resistant weeds and several glyphosate-tolerant species common in the region. As a result, the control of summer fallow weeds is become more complex. This paper outlines project work investigating improved weed control for summer fallows in the northern cropping region. Areas of research include weed ecology, chemical and non-chemical tactics, glyphosate resistance and resistance surveys. The project also has an economic and extension component. As a result of our research we have a better understanding of the ecology of major northern weeds and spread of glyphosate resistance in the region. We have identified and defined alternative herbicide and non-chemical approaches for the effective control of summer fallow weeds and have extended our research effectively to industry.

Bound states of two spin-1/2 fermions in a synthetic non-Abelian gauge field

We study the bound states of two spin-1/2 fermions interacting via a contact attraction (characterized by a scattering length) in the singlet channel in three-dimensional space in presence of a uniform non-Abelian gauge field. The configuration of the gauge field that generates a Rashba-type spin-orbit interaction is described by three coupling parameters (lambda(x),lambda(y),lambda(z)). For a generic gauge field configuration, the critical scattering length required for the formation of a bound state is negative, i.e., shifts to the ``BCS side'' of the resonance. Interestingly, we find that there are special high-symmetry configurations (e.g., lambda(x) = lambda(y) = lambda(z)) for which there is a two-body bound state for any scattering length however small and negative. Remarkably, the bound-state wave functions obtained for such configurations have nematic spin structure similar to those found in liquid He-3. Our results show that the BCS-BEC (Bose-Einstein condensation) crossover is drastically affected by the presence of a non-Abelian gauge field. We discuss possible experimental signatures of our findings both at high and low temperatures.

Rashbons: properties and their significance

In the presence of a synthetic non-Abelian gauge field that produces a Rashba-like spin-orbit interaction, a collection of weakly interacting fermions undergoes a crossover from a Bardeen-Cooper-Schrieffer (BCS) ground state to a Bose-Einstein condensate (BEC) ground state when the strength of the gauge field is increased (Vyasanakere et al 2011 Phys. Rev. B 84 014512). The BEC that is obtained at large gauge coupling strengths is a condensate of tightly bound bosonic fermion pairs. The properties of these bosons are solely determined by the Rashba gauge field-hence called rashbons. In this paper, we conduct a systematic study of the properties of rashbons and their dispersion. This study reveals a new qualitative aspect of the problem of interacting fermions in non-Abelian gauge fields, i.e. that the rashbon state ceases to exist when the center-of-mass momentum of the fermions exceeds a critical value that is of the order of the gauge coupling strength. The study allows us to estimate the transition temperature of the rashbon BEC and suggests a route to enhance the exponentially small transition temperature of the system with a fixed weak attraction to the order of the Fermi temperature by tuning the strength of the non-Abelian gauge field. The nature of the rashbon dispersion, and in particular the absence of the rashbon states at large momenta, suggests a regime in parameter space where the normal state of the system will be a dynamical mixture of uncondensed rashbons and unpaired helical fermions. Such a state should show many novel features including pseudogap physics.

Fermions in synthetic non-Abelian gauge potentials: rashbon condensates to novel Hamiltonians

Recent advances in the generation of synthetic gauge fields in cold atomic systems have stimulated interest in the physics of interacting bosons and fermions in them. In this paper, we discuss interacting two-component fermionic systems in uniform non-Abelian gauge fields that produce a spin-orbit interaction and uniform spin potentials. Two classes of gauge fields discussed include those that produce a Rashba spin-orbit interaction and the type of gauge fields (SM gauge fields) obtained in experiments by the Shanxi and MIT groups. For high symmetry Rashba gauge fields, a two-particle bound state exists even for a vanishingly small attractive interaction described by a scattering length. Upon increasing the strength of a Rashba gauge field, a finite density of weakly interacting fermions undergoes a crossover from a BCS like ground state to a BEC state of a new kind of boson called the rashbon whose properties are determined solely by the gauge field and not by the interaction between the fermions. The rashbon Bose-Einstein condensate (RBEC) is a quite intriguing state with the rashbon-rashbon interactions being independent of the fermion-fermion interactions (scattering length). Furthermore, we show that the RBEC has a transition temperature of the order of the Fermi temperature, suggesting routes to enhance the transition temperatures of weakly interacting superfluids by tuning the spin-orbit coupling. For the SM gauge fields, we show that in a regime of parameters, a pair of particles with finite centre-of-mass momentum is the most strongly bound. In other regimes of centre-of-mass momenta, there is no two-body bound state, but a resonance like feature appears in the scattering continuum. In the many-body setting, this results in flow enhanced pairing. Also, strongly interacting normal states utilizing the scattering resonance can be created opening the possibility of studying properties of helical Fermi liquids. This paper contains a general discussion of the physics of Feshbach resonance in a non-Abelian gauge field, where several novel features such as centre-of-mass-momentum-dependent effective interactions are shown. It is also shown that a uniform non-Abelian gauge field in conjunction with a spatial potential can be used to generate novel Hamiltonians; we discuss an explicit example of the generation of a monopole Hamiltonian.

Prudentia Iuris, 1983, n° 11 (número completo)

Contenido: Editorial – La incidencia institucional en la historia de textos jurídicos / Álvaro D’Ors – El derecho indiano / Ricardo Zorraquín Becú – Apostillas en torno al tema de la responsabilidad / Carlos Raúl Sanz – El valor de la justicia en las corrientes socio-políticas modernas / Federico Mihura Seeber – Notas introductorias al estudio del pensamiento político y jurídico de San Agustín / Escolios – Documentos – Notas bibliográficas

Temas de historia argentina y americana, 2007, n° 10 (número completo)

Un notable historiador eclesiástico argentino, el canónigo doctor Américo A. Tonda / Miguel Ángel De Marco -- Carlos Vega, a cuarenta años de su muerte (1966-2006) / Santiago Miguel Giacosa -- La situación del trabajador español en la Argentina a principios del siglo XX / Rosario Güenaga -- El aporte extranjero a la conformación de las tripulaciones de las escuadras argentinas en las Guerras de Independencia y del Brasil, 1814-1830 / Julio M. Luqui-Lagleyze -- Ricardo Zorraquín Becú y la crisis del imperio hispano indiano / Eduardo Martiré -- España y la emergencia del poder americano, 1902-1936 / José Luis Neila Hernández -- El retorno de Perón al poder reflejado en la prensa israelí – Argentina, Israel y los judíos, 1973-74 / Raanan Rein -- Juan Moreira: la transformación de un gaucho cuchillero en personaje de ópera italiana / Juan María Veniard -- Reseñas Bibliográficas

Prudentia Iuris, 1992, n° 29 (número completo)

Contenido: Sinopsis de la jurisdicción originaria de la Corte Suprema de Justicia de la Nación / Sergio O. Dugo – Los instrumentos de la seguridad social / José Benjamín Gómez Paz – El derecho : ¿realidad o norma moral? A propósito de la tesis de Michel Villey / José Jorge Coviello – Europa y América : en torno al descubrimiento / Ricardo Zorraquín Becú – Notas sobre la Iglesia en América / Carlos M. Storni – Independencia política y continuidad cultural : formación inicial argentina / Liniers de Estrada – La sanción del daño moral en el derecho romano / Juan José Alba Crespo – Mesianismo y escatología en el descubrimiento de América / Florencio Hubeñak – Reunificación / Francisco Arias Pelerano – El estudio de los procesos de integración : importancia e implicancias de un enfoque político / Leonardo Hekimián

Nuevos planteamientos en la imagen fotográfica, arte hibridación y nuevas tecnologías

Ponencia leída en el Foro de Comunicaciones IkasArt III (BEC Barakaldo, 2011.11.11)

Aproximación fenomenológica al concepto de refugio temporal: anacronismos de una construcción inestable

Ponencia leída en el Foro de Comunicaciones IkasArt III (BEC Barakaldo, 2011.11.11)[por Skype]

Sobre la conveniencia de aunar teoría y práctica en la investigación doctoral en las Bellas Artes

Ponencia leída en el Foro de Comunicaciones IkasArt III (BEC Barakaldo, 2011.11.11)

La asistencia digital en la producción y reproducción de la imagen pictórica: una propuesta docente

Ponencia leída en el Foro de Comunicaciones IkasArt III (BEC Barakaldo, 2011.11.11)

Arte y ecología: hacia nuevo método de análisis de las actividades artísticas relacionadas con la naturaleza

Ponencia leída en el Foro de Comunicaciones IkasArt III (BEC Barakaldo, 2011.11.11)

El vídeo-tutorial: una valiosa herramienta para el b-learning

Ponencia leída en el Foro de Comunicaciones IkasArt III (BEC Barakaldo, 2011.11.11)

1987: Resistance (anti-Baudrillard)

Ponencia leída en el Foro de Comunicaciones IkasArt II (BEC Barakaldo, 2010.06.17)

Andar dándole vueltas a algo

Ponencia leída en el Foro de Comunicaciones IkasArt II (BEC Barakaldo, 2010.06.17)