Non-analyticities in three-dimensional gauge theories

Quantum fluctuations generate in three-dimensional gauge theories not only radiative corrections to the Chern-Simons coupling but also non-analytic terms in the effective action. We review the role of those terms in gauge theories with massless fermions and Chern-Simons theories. The explicit form of non-analytic terms turns out to be dependent on the regularization scheme and in consequence the very existence of phenomena like parity and framing anomalies becomes regularization dependent. In particular we find regularization regimes where both anomalies are absent. Due to the presence of non-analytic terms the effective action becomes not only discontinuous but also singular for some background gauge fields which include sphalerons. The appearence of this type of singularities is linked to the existence of nodal configurations in physical states and tunneling suppression at some classical field configurations. In the topological field theory the number of physical states may also become regularization dependent. Another consequence of the peculiar behaviour of three-dimensional theories under parity odd regularizations is the existence of a simple mechanism of generation of a mass gap in pure Yang-Mills theory by a suitable choice of regularization scheme. The generic value of this mass does agree with the values obtained in Hamiltonian and numerical analysis. Finally, the existence of different regularization regimes unveils the difficulties of establishing a Zamolodchikov c-theorem for three-dimensional field theories in terms of the induced gravitational Chern-Simons couplings.Comment: 21 pages; Contribution to Ian Kogan Memorial Collection, ``From Fields to Strings: Circumnavigating Theoretical Physics'

Analysis of water-soluble vitamins in biopharma raw materials by electrophoresis micro-chips with contactless conductivity detection

Detailed information concerning the composition of the raw materials employed in the production of biologics is important for the efficient control and optimization of bioprocesses. The analytical methods used in these applications must be simple and fast as well as be easily transferable from one site to another. In that context, microchip‐based electrophoresis represents a promising tool for application in the analysis of raw materials in biologics. Using electrophoresis micro‐chips, analysis times can be reduced to seconds and high separation efficiencies can be achieved using extremely low volume samples, minimal reagent consumption and waste generation, low cost/disposability, portability and ease of mass‐production [1]. Additionally the use of Capacitively Coupled Contactless Conductivity Detection (C4D) offers a rather simple and yet sensitive method for detection of ionic species. Recently, C4D has gained much popularity as on‐chip detection in electrophoresis micro‐chips [2]. The main reason for this is that there is no physical contact of the detection electrodes with the electrolyte solution. Therefore, the integration of this detection mode within the analytical system is rather simple. Furthermore, the background noise is significantly reduced leading to lower detection limits than the conventional contact conductivity detection. Vitamins are present at very low concentrations in biopharma raw materials and are usually determined using HPLC and CE methods [3]. Electrophoresis micro‐chips are a very good alternative to these techniques due to the shorter analysis time and yet very good resolution, among others. In this paper, we present the application of electrophoresis micro‐chips with C4D detection to the analysis of water‐soluble vitamins in raw materials used for the production of biologics in bioreactors. For that purpose, hybrid PDMS/glass chips were fabricated by using standard photolithographic techniques (Figure 1). The chip structure contains an extremely long channel of 101 mm (50 x 50 μm width x depth). Figure 2 shows the setup used for vitamins detection

Role of Cerebellar Interpositus Nucleus in the Genesis and Control of Reflex and Conditioned Eyelid Responses

The role of cerebellar circuits in the acquisition of new motor abilities is still a matter of intensive debate. To establish the contribution of posterior interpositus nucleus (PIN) to the performance and/or acquisition of reflex and classically conditioned responses (CRs) of the eyelid, the effects of microstimulation and/or pharmacological inhibition by muscimol of the nucleus were investigated in conscious cats. Microstimulation of the PIN in naive animals evoked ramp-like eyelid responses with a wavy appearance, without producing any noticeable plastic functional change in the cerebellar and brainstem circuits involved. Muscimol microinjections decreased the amplitude of reflex eyeblinks evoked by air puffs, both when presented alone or when paired with a tone as conditioned stimulus (CS). In half-conditioned animals, muscimol injections also decreased the amplitude and damped the typical wavy profile of CRs, whereas microstimulation of the same sites increased both parameters. However, neither muscimol injections nor microstimulation modified the expected percentage of CRs, suggesting a major role of the PIN in the performance of eyelid responses rather than in the learning process. Moreover, the simultaneous presentation of CS and microstimulation in well trained animals evoked CRs similar in amplitude to the added value of those evoked by the two stimuli presented separately. In contrast, muscimol-injected animals developed CRs to paired CS and microstimulation presentations, larger than those evoked by the two stimuli when presented alone. It is concluded that the PIN contributes to the enhancement of both reflex and conditioned eyelid responses and to the damping of resonant properties of neuromuscular elements controlling eyelid kinematics

IR diagnostics of embedded jets: velocity resolved observations of the HH34 and HH1 jets

We present VLT-ISAAC medium resolution spectroscopy of the HH34 and HH1 jets. Our aim is to derive the kinematics and the physical parameters and to study how they vary with jet velocity. We use several important diagnostic lines such as [FeII] 1.644um, 1.600um and H2 2.122um. In the inner jet region of HH34 we find that both the atomic and molecular gas present two components at high and low velocity. The [FeII] LVC in HH34 is detected up to large distances from the source (>1000 AU), at variance with TTauri jets. In H2 2.122um, the LVC and HVC are spatially separated. We detect, for the first time, the fainter red-shifted counterpart down to the central source. In HH1, we trace the jet down to ~1" from the VLA1 driving source: the kinematics of this inner region is again characterised by the presence of two velocity components, one blue-shifted and one red-shifted with respect to the source LSR velocity. In the inner HH34 jet region, ne increases with decreasing velocity. Up to ~10" from the driving source, and along the whole HH1 jet an opposite behaviour is observed instead, with ne increasing with velocity. In both jets the mass flux is carried mainly by the high-velocity gas. A comparison between the position velocity diagrams and derived electron densities with models for MHD jet launching mechanisms has been performed for HH34. While the kinematical characteristics of the line emission at the jet base can be, at least qualitatively, reproduced by both X-winds and disc-wind models, none of these models can explain the extent of the LVC and the dependence of electron density with velocity that we observe. It is possible that the LVC in HH34 represents gas not directly ejected in the jet but instead denser ambient gas entrained by the high velocity collimated jet.Comment: A&A accepte

Analysis of biopharma raw materials by electrophoresis microchips with contactless conductivity detection

Detailed information concerning the composition of the raw materials employed in the production of biologics is important for the efficient control and optimization of bioprocesses. We demonstrate the application of electrophoresis microchips with capacitively-coupled contactless conductivity detection (C4D) to the analysis of wa-ter-soluble vitamins and metal cations in raw material solutions that are subse-quently fed into bioreactors for the production of biologics

Caracterização do mercado de manga na União Europeia.

O objetivo desta pesquisa foi fazer a caracterização do mercado de manga na União Europeia, que é o principal mercado importador da manga brasileira. O método utilizado para a execução desta pesquisa foi a entrevista de profundidade, que contemplou importadores, atacadistas, supervisores do setor de produtos hortifrutícolas de supermercados e gerentes de lojas de frutas da Espanha, além de agentes comerciais de outros países comunitários. Os resultados do estudo revelaram que a tendência atual do mercado de manga na União Europeia é de ampliação do consumo. No tocante à conduta de mercado das principais variedades de mangas ali comercializadas se constatou que a Tommy Atkins tem em termos de seu ciclo de vida comercial duas fases: a de maturidade com tendência descendente e a de declínio. A Kent tem a fase de maturidade com tendência ascendente. As variedades Haden e Keitt estão na fase de maturidade estável, enquanto as variedades Palmer, Maya e Shelly encontram-se na fase de crescimento. Com referência à segmentação de mercado de manga fresca, o estudo aponta quatro segmentos bem definidos: o composto pelos consumidores, que priorizam a relação qualidade/preços competitivos, o segmento dos consumidores de produtos prêmios, o segmento dos consumidores de produtos orgânicos e o segmento dos consumidores de produtos minimamente processados ou de quarta gama.bitstream/item/56818/1/BPD92.pd

Non-linear response of single-molecule magnets: field-tuned quantum-to-classical crossovers

Quantum nanomagnets can show a field dependence of the relaxation time very different from their classical counterparts, due to resonant tunneling via excited states (near the anisotropy barrier top). The relaxation time then shows minima at the resonant fields H_{n}=n D at which the levels at both sides of the barrier become degenerate (D is the anisotropy constant). We showed that in Mn12, near zero field, this yields a contribution to the nonlinear susceptibility that makes it qualitatively different from the classical curves [Phys. Rev. B 72, 224433 (2005)]. Here we extend the experimental study to finite dc fields showing how the bias can trigger the system to display those quantum nonlinear responses, near the resonant fields, while recovering an classical-like behaviour for fields between them. The analysis of the experiments is done with heuristic expressions derived from simple balance equations and calculations with a Pauli-type quantum master equation.Comment: 4 pages, 3 figures. Submitted to Phys. Rev. B, brief report

Weak positive cloud-to-ground flashes in Northeastern Colorado

The frequency distributions of the peak magnetic field associated with the first detected return stroke of positive and negative cloud-to-ground (CG) flashes were studied using lightning data from northeastern Colorado. These data were obtained during 1985 with a medium-to-high gain network of three direction finders (DF's). The median signal strength of positive flashes was almost two times that of the negatives for flashes within 300 km of the DF's, which have an inherent detection-threshold bias that tends to discriminate against weak signals. This bias increases with range, and affects the detection of positive and negative flashes in different ways, because of the differing character of their distributions. Positive flashes appear to have a large percentage of signals clustered around very weak values that are lost to the medium-to-high gain Colorado Detection System very quickly with increasing range. The resulting median for positive signals could thus appear to be much larger than the median for negative signals, which are more clustered around intermediate values. When only flashes very close to the DF's are considered, however, the two distributions have almost identical medians. The large percentage of weak positive signals detected close to the DF's has not been explored previously. They have been suggested to come from intracloud discharges and thus are improperly classified as CG flashes. Evidence in hand, points to their being real positive, albeit weak CG flashes. Whether or not they are real positive ground flashes, it is important to be aware of their presence in data from magnetic DF networks