Chaotic scattering with direct processes: A generalization of Poisson's kernel for non-unitary scattering matrices

The problem of chaotic scattering in presence of direct processes or prompt responses is mapped via a transformation to the case of scattering in absence of such processes for non-unitary scattering matrices, \tilde S. In the absence of prompt responses, \tilde S is uniformly distributed according to its invariant measure in the space of \tilde S matrices with zero average, < \tilde S > =0. In the presence of direct processes, the distribution of \tilde S is non-uniform and it is characterized by the average (\neq 0). In contrast to the case of unitary matrices S, where the invariant measures of S for chaotic scattering with and without direct processes are related through the well known Poisson kernel, here we show that for non-unitary scattering matrices the invariant measures are related by the Poisson kernel squared. Our results are relevant to situations where flux conservation is not satisfied. For example, transport experiments in chaotic systems, where gains or losses are present, like microwave chaotic cavities or graphs, and acoustic or elastic resonators.Comment: Added two appendices and references. Corrected typo

Applications of Direct Injection Soft Chemical Ionisation-Mass Spectrometry for the Detection of Pre-blast Smokeless Powder Organic Additives

Analysis of smokeless powders is of interest from forensics and security perspectives. This article reports the detection of smokeless powder organic additives (in their pre-detonation condition), namely the stabiliser diphenylamine and its derivatives 2-nitrodiphenylamine and 4-nitrodiphenylamine, and the additives (used both as stabilisers and plasticisers) methyl centralite and ethyl centralite, by means of swab sampling followed by thermal desorption and direct injection soft chemical ionisation-mass spectrometry. Investigations on the product ions resulting from the reactions of the reagent ions H3O+ and O2+ with additives as a function of reduced electric field are reported. The method was comprehensively evaluated in terms of linearity, sensitivity and precision. For H3O+, the limits of detection (LoD) are in the range of 41-88 pg of additive, for which the accuracy varied between 1.5 and 3.2%, precision varied between 3.7 and 7.3% and linearity showed R20.9991. For O2+, LoD are in the range of 72 to 1.4 ng, with an accuracy of between 2.8 and 4.9% and a precision between 4.5 and 8.6% and R20.9914. The validated methodology was applied to the analysis of commercial pre-blast gun powders from different manufacturers.(VLID)4826148Accepted versio

Neural basis for categorical boundaries in the primate pre-SMA during relative categorization of time intervals

This is the final version. Available on open access from Nature Research via the DOI in this recordPerceptual categorization depends on the assignment of different stimuli to specific groups based, in principle, on the notion of flexible categorical boundaries. To determine the neural basis of categorical boundaries, we record the activity of pre-SMA neurons of monkeys executing an interval categorization task in which the limit between short and long categories changes between blocks of trials within a session. A large population of cells encodes this boundary by reaching a constant peak of activity close to the corresponding subjective limit. Notably, the time at which this peak is reached changes according to the categorical boundary of the current block, predicting the monkeys' categorical decision on a trial-by-trial basis. In addition, pre-SMA cells also represent the category selected by the monkeys and the outcome of the decision. These results suggest that the pre-SMA adaptively encodes subjective duration boundaries between short and long durations and contains crucial neural information to categorize intervals and evaluate the outcome of such perceptual decisions

Electroactive tape extrusion : influence of processing conditions on the β-phase content of PVDF samples

Poly(vinylidene fluoride), PVDF, in its polar β-phase, is known to possess strong piezoelectric properties, among polymers. The α phase of PVDF is the most stable phase when the polymer crystallizes from the melt. In this way, the electroactive phase of the material is commonly obtained by inducing the α to β phase transformation through mechanical stretching at a given temperature, being the stretch ratio and temperature the most important parameters influencing the phase transformation [1]. Further, it has been demonstrated that the electroactive response of the material strongly depends on the β-phase and therefore on the processing conditions [2]. In the present work, the effect of processing variables in the content of β-phase PVDF extruded tape, namely the stretching ratio and process temperatures, was studied. For comparison purposes the produced samples were uniaxially stretched with ratios of up to 6, in the extrusion line (in-line) and in a tensile tester (off-line), at both 80ºC and 120ºC. The β-phase content was analysed by Fourier transform infrared spectroscopy (FTIR) and the electroactive phase content was correlated to the electroactive response of the material, obtained through the measurement of the d33 piezoelectric coefficient. The results obtained allowed to identify the most important parameters influencing the amount of the β-phase content and will be used as guidance for the development of a large scale production process for multilayer products with piezoelectric properties.FCT- Portuguese Foundation for Science and Technology through the project PTDC/CTM/108801/2008 and FEDER via FCT, Fundação para a Ciência e Tecnologia, under the POCI 2010 and Pluriannual program

Influence of processing conditions on the β-Phase content of PVDF samples produced by tape extrusion

This research team has been working during the last couple of years on the development of industrial scalable technologies, based on the extrusion processing technique, for the prodution of piezoeletric products. This specific work comprises a study on the effect of tape extrusion processing conditions on the content of PVDF β-phase. For this purpose the extruded samples were uniaxially stretched up to ratios of 6, at 80ºC and 120ºC, being the β-phase content analysed by FTIR. Subsequently, the samples were corona poled and their piezoelectric coefficient d33 was measured. The results obtained allowed to conclude that the extrusion processing variables, with the exception of the stretching temperature and ratio, do not have a strong influence on the β-phase content and piezoelectric response of PVDF.Fundação para a Ciência e a Tecnologia (FCT

Diagnóstico de producción en ganado lechero en pastoreo de un grupo ganadero de validación y transferencia de tecnología

The regionalization of framing issues for producers Livestock Group of Validation and Technology Transfer (GGAVATT) from San Jose Miahuatlán Veracruz, Mexico, under the current production of native grass prairie with mainly during the months of higher temperature have a poor performance and thus milk production declines which promotes a great use of concentrated feeds which causes an increase in production cost and less use to them. For this purpose we made a diagnosis of current conditions GGAVATT production, yielding information that helps us source and compared to determine precisely what the effect of applying the proposed alternative. We propose an alternative implementation of pastures with improved pastures needed to produce a greater amount of forage per unit area especially in the colder months.La regionalización de la problemática encuadrando a los productores del Grupo Ganadero de Validación y Transferencia de Tecnología (GGAVATT) de San José Miahuatlán Veracruz, México, bajo la actual situación de producción de praderas básicamente con gramas nativas que durante los meses de menor frío tienen un pobre desempeño y por ende la producción de leche se deteriora lo cual promueve una gran utilización de alimentos concentrados lo que provoca un incremento en el costo de producción y una menor utilidad para estos. Para dicho propósito se realizó un diagnóstico de las condiciones actuales de producción del GGAVATT, arrojando información que nos sirve de partida y de comparación para determinar con precisión cuál es el efecto de aplicar la alternativa propuesta. Se plantea como alternativa la implantación de praderas con pastos mejorados que permitan producir una mayor cantidad de forrajes por unidad de superficie sobre todo en los meses de menor temperatura

Top Radiative Corrections in Non-minimal Standard Models

We derive the one-loop effective action induced by a heavy top in models with an extended Higgs sector. We use the effective action to analyze the top corrections to the $\rho$ parameter and to the Higgs-gauge boson couplings. We show that in models with $\rho\not=1$ at tree-level, one does not lose generally the bound on $m_t$ from the $\rho$ parameter.Comment: 9 pages, phyzzx file, UPR-0603T. (a new reference has been added

Periodic Chaotic Billiards: Quantum-Classical Correspondence in Energy Space

We investigate the properties of eigenstates and local density of states (LDOS) for a periodic 2D rippled billiard, focusing on their quantum-classical correspondence in energy representation. To construct the classical counterparts of LDOS and the structure of eigenstates (SES), the effects of the boundary are first incorporated (via a canonical transformation) into an effective potential, rendering the one-particle motion in the 2D rippled billiard equivalent to that of two-interacting particles in 1D geometry. We show that classical counterparts of SES and LDOS in the case of strong chaotic motion reveal quite a good correspondence with the quantum quantities. We also show that the main features of the SES and LDOS can be explained in terms of the underlying classical dynamics, in particular of certain periodic orbits. On the other hand, statistical properties of eigenstates and LDOS turn out to be different from those prescribed by random matrix theory. We discuss the quantum effects responsible for the non-ergodic character of the eigenstates and individual LDOS that seem to be generic for this type of billiards with a large number of transverse channels.Comment: 13 pages, 18 figure