Renormalization and finiteness of topological BF theories

We show that the BF theory in any space-time dimension, when quantized in a certain linear covariant gauge, possesses a vector supersymmetry. The generator of the latter together with those of the BRS transformations and of the translations form the basis of a superalgebra of the Wess-Zumino type. We give a general classification of all possible anomalies and invariant counterterms. Their absence, which amounts to ultraviolet finiteness, follows from purely algebraic arguments in the lower-dimensional cases.Comment: 27 p., Latex fil

Simple Ginzburg-Landau Theory for Vortices in a Crystal Lattice

We study the Ginzburg-Landau model with a nonlocal quartic term as a simple phenomenological model for superconductors in the presence of coupling between the vortex lattice and the underlying crystal lattice. In mean-field theory, our model is consistent with a general oblique vortex lattice ranging from a triangular lattice to a square lattice. This simple formulation enables us to study the effect of thermal fluctuations in the vortex liquid regime. We calculate the structure factor of the vortex liquid nonperturbatively and find Bragg-like peaks with four-fold symmetry appearing in the structure factor even though there is only a short-range crystalline order.Comment: Revised version with new title and additional results for the vortex liquid regime, to be published in Phys. Rev. Lett. 5 pages RevTeX, 1 figure include

Neoadjuvant Use of Photodynamic Therapy in Basal Cell and Squamous Cell Carcinomas of the Face

Background. This preliminary study sought to determine the success of photodynamic therapy (PDT) in reducing lesion size in an effort to assess the potential application of this treatment approach in a neoadjuvant role. Objectives. To quantify the effects of PDT on lesion area (mm2) for basal cell and squamous cell carcinomas of the face. Results. Eighteen participants (10 BCC lesions and 8 SCC lesions of the face) were assessed. Four lesions (all from the BCC group) showed a complete response to PDT. Of the remaining 14 lesions, 85.7% (n = 12) showed reductions in lesion area, while two lesions showed increase in lesion area. Proportional reductions for the 12 lesions that did not demonstrate complete response or an increase in area following-PDT were found to range from 13.2% to 85.1% (BCC) and 6.7% to 89.7% (SCC). Conclusions. PDT as a neoadjuvant treatment may provide a simple, efficient, and viable approach to reducing the area of malignant lesions of the face with the advantage of reduced cosmetic and aesthetic morbidities

Helicity Modulus and Meissner Effect in a Fluctuating Type II Superconductor

The helicity modulus for a fluctuating type II superconductor is computed within the elastic medium approximation, as a probe of superconducting phase coherence and the Meissner effect in the mixed state. We argue that at the vortex line lattice melting transition, there remains superconducting coherence parallel to the applied magnetic field, provided the vortex line liquid retains a finite shear modulus at finite wavevector.Comment: 10 pages, 0 figures, RevTex3.0, UR-93-ST0

An ultrastructural investigation of the surface microbiota present on the leaves and reproductive structures of the resurrection plant Myrothamnus flabellifolia

The leaves, flower and stems of the southern African angiosperm resurrection plant Myrothamnus flabellifolia were investigated at the ultrastructural level to determine the source of previously reported fungal contamination. Fungal mycelia and hyphae of the genera Aspergillus and Penicillium were found localized to the hydathodes of the leaves and stigmatic surfaces of the female flowers in both desiccated and hydrated specimens. A waxy bacterium of the genus Bacillus was found to colonise the waxy epidermal surfaces of the leaves and flowers which was also where fungal cells were found to be absent. It is suggested that the wax like deposits within the leaves and stems as well as over the epidermal surface prevent the growth of the fungal organisms. These fungi opportunistically invade moist surfaces, such as the floral stigmas, during periods of moisture availability and may thus negatively impact plant development

14-3-3 proteins. a highly conserved, widespread family of eukaryotic proteins

A family of proteins known as 14-3-3 is currently receiving increased attention by investigators studying a broad range of biological systems, including plants and invertebrates. The outstanding feature of this family is the extraordinarily high sequence conservation observed. Current thinking indicates that these proteins may function as regulators in signal tranduction/phosphorylation mechanisms

Cosmological Structure Formation under MOND: a new numerical solver for Poisson's equation

We present a novel solver for an analogue to Poisson's equation in the framework of modified Newtonian dynamics (MOND). This equation is highly non-linear and hence standard codes based upon tree structures and/or FFT's in general are not applicable; one needs to defer to multi-grid relaxation techniques. After a detailed description of the necessary modifications to the cosmological N-body code AMIGA (formerly known as MLAPM) we utilize the new code to revisit the issue of cosmic structure formation under MOND. We find that the proper (numerical) integration of a MONDian Poisson's equation has some noticable effects on the final results when compared against simulations of the same kind but based upon rather ad-hoc assumptions about the properties of the MONDian force field. Namely, we find that the large-scale structure evolution is faster in our revised MOND model leading to an even stronger clustering of galaxies, especially when compared to the standard LCDM paradigm.Comment: 15 pages, 20 figures. Accepted for publication in MNRA

Instabilities in the Flux Line Lattice of Anisotropic Superconductors

The stability of the flux line lattice has been investigated within anisotropic London theory. This is the first full-scale investigation of instabilities in the `chain' state. It has been found that the lattice is stable at large fields, but that instabilities occur as the field is reduced. The field at which these instabilities first arise, $b^*(\epsilon,\theta)$, depends on the anisotropy $\epsilon$ and the angle $\theta$ at which the lattice is tilted away from the $c$-axis. These instabilities initially occur at wavevector $k^*(\epsilon,\theta)$, and the component of $k^*$ along the average direction of the flux lines, $k_z$, is always finite. As the instability occurs at finite $k_z$ the dependence of the cutoff on $k_z$ is important, and we have used a cutoff suggested by Sudb\ospace and Brandt. The instabilities only occur for values of the anisotropy $\epsilon$ appropriate to a material like BSCCO, and not for anisotropies more appropriate to YBCO. The lower critical field $H_{c_1}(\phi)$ is calculated as a function of the angle $\phi$ at which the applied field is tilted away from the crystal axis. The presence of kinks in $H_{c_1}(\phi)$ is seen to be related to instabilities in the equilibrium flux line structure.Comment: Extensively revised paper, with modified analysis of elastic instabilities. Calculation of the lower critical field is included, and the presence of kinks in $H_{c_1}$ is seen to be related to the elastic instabilities. 29 pages including 16 figures, LaTeX with epsf styl

Agriculture in Taiwan and South Korea: the minimalist state?

SUMMARY The state has intervened heavily in the agricultural economies of Taiwan and South Korea, both by direct administrative means and by establishing price relativities very different from those set by market forces. Although state action has not always been effective or efficient, it has played a major role in making agriculture serve the objective of rapid industrial growth. The forms and consequences of state intervention have changed over time in response to the political and economic pressures arising from structural economic change. The state has been obliged to be interventionist in order to try to maintain the political order on which continual reinvestment and thus continued growth depend. RESUMEN Agricultura en Taiwán y Corea del Sur: estado minimalista? El estado ha intervenido fuertemente en la economía agrícola en ambos países, tanto por medios directamente administrativos, como por el establecimento de precios relativos muy diferentes de aquellos derivados de la acción de las fuerzas del mercado. Aunque no siempre la acción estatal ha sido efectiva o eficiente, ha jugado un rol principal para que la agricultura sirva los objetivos de un rápido crecimiento industrial. Las formas y consecuencias de la intervención estatal han cambiado a través del tiempo, como respuesta a las presiones económicas derivadas del cambio en la estructura económica. El estado se ha visto obligado a ser intervencionista para tratar de mantener el orden politico del cual depende la continua reínversíón y, en consecuencia, el crecimiento persistente. RESUMES L'agriculture à Taiwan et en Corée du Sud: l'état minimaliste? L'état a intervenu de façon très importante dans les économies agricoles de Taiwan et de la Corée du Sud, par des moyens administratifs directs et en établissant une relativité des prix très différente de celle établie par les forces de marché. Quoique l'action de l'état n'ait pas toujours été effective ou efficace, elle a joué un rôle de grande importance en se servant de l'agriculture pour aider une croissance industrielle rapide. Les formes et les conséquences de l'intervention de l'état ont changé au cours des temps en fonction des pressions politiques et économiques provenant du changement de la structure économique. L'état a été obligé d'être interventionniste de façon à essayer de maintenir l'ordre politique duquel dépendent le rèinvestissement continu et donc la croissance continue

Mars Express/ASPERA-3/NPI and IMAGE/LENA observations of energetic neutral atoms in Earth and Mars orbit

The low energy neutral atom imagers on Mars Express and IMAGE have revealed that the neutral atom populations in interplanetary space come from a variety of sources and challenge our current understanding of heliospheric physics. For example, both in cruise phase and at Mars, the neutral particle instrument NPD on Mars Express observed "unexplained neutral beams" unrelated to Mars which appear to be either of heliospheric or solar wind origin. Likewise, the NPI instrument on Mars Express has revealed streams of neutral atoms with different properties than those observed by NPD. Independently, IMAGE/LENA has reported neutral atom observations that may be interpreted as a "secondary stream" having different characteristics and flowing from a higher ecliptic longitude than the nominal upstream direction. Both sets of observations do not appear to fit in easily with the neutral atom environment from 1.0-1.57 AU as it is currently understood. In this paper we examine some highly suggestive similarities in the IMAGE/LENA and Mars Express/ASPERA-3/NPI data to try to determine potential origins for the observed signal.Comment: in press Adv. Sp. Res., 15 pages, 9 figure