Analysis of non-coloured phenolics in port wines by capillary zone electrophoresis Influence of grape variety and ageing

 Different experimental varietal port wines were analysed in order to determine differences in the concentrations of phenolic compounds between some commonly used grapes varieties (Touriga Francesa, Touriga Nacional, Tinta Roriz and Tinta Barroca). Although all samples had the same qualitative pattern of non-coloured phenolic compounds, Touriga varieties contained more than twice the concentration of these compounds compared to the Tinta varieties. A preliminary study of the effect of ageing on these compounds revealed an overall increase in those components associated with the bitter or astringent characteristics of food and beverages (tyrosol, gallic acid and catechin). Received: 1 August 1997     

Modeling fast link adaptation-based 802.11n distributed coordination function

This paper presents a comprehensive performance study of closed-loop fast link adaptation (FLA) in the context of IEEE 802.11n, spanning the physical (PHY) and medium-access control (MAC) layers. In particular, a semi-analytical model is derived for Basic and request to send/clear to send (RTS/CTS) access schemes of the distributed coordination function (DCF), that applies to both, open- and closed-loop strategies. Numerical results serve to demonstrate the accuracy of the proposed model and the superiority of FLA, in terms of MAC goodput, in comparison to open-loop policies. Realistic operating conditions such as outdated feedback information and the use of statistical packet length distributions, issues not treated in previous studies, have also been considered. Moreover, it is shown that incorporating a time-out mechanism in the FLA scheme, weighing down the influence of channel information as this becomes outdated, is a useful strategy to counteract its deleterious effects.     

Enhancing IEEE 802.11n WLANs using group-orthogonal code-division multiplex

The definition of the next generation of wireless networks is well under way within the IEEE 802.11 High Throughput Task Group committee. The resulting standard, to be called IEEE 802.11n, is expected to be a backward-compatible evolution of the successful IEEE 802.11a/g systems also based on multicarrier techniques. It can be anticipated that 802.11n systems will outperform its predecessors in terms of transmission rate and/or performance, mainly, due to the use of multiple antennae technology for transmission and reception. In this paper we propose to incorporate group-orthogonal (GO) code division multiplex (CDM) into the IEEE 802.11n specifications to further enhance its performance. It is shown how GO-CDM can take full advantage of the diversity offered by the multiple antennae and multicarrier transmission by using an iterative maximum likelihood (ML) joint detector. Furthermore, the use of GO-CDM does not compromise the backward compatibility with legacy systems.     

Sound mapping for identification of stability lobe diagrams in milling processes

This paper deals with milling sound information. In milling operations, cutting edge impacts excite vibrations due to the interaction between the cutter and the workpiece, and because of the system's lack of dynamic stiffness. It is possible to distinguish between free, forced and self-excited vibrations. During a milling operation these three different types of mechanical vibrations propagate through air and generate a sound that intrinsically contains information about the process.A sound map is a graphical sound-level representation of a certain zone or region that is divided into points by means of a mesh. Sound maps have typically been used with social considerations in mind: to determine, for instance, noise levels in cities. The goal of this paper is to determine the stability lobe diagram (SLD) of a milling process by applying sound mapping methodology. Stability lobe diagrams show the stability frontier as combinations of spindle speeds (i.e. the abscissas axis) and radial depths of cut (i.e. the ordinate axis). In this investigation the SLD was obtained from a mesh of 30 spindle speeds per 20 axial depths of cut, resulting in a total of 600 experiments. A data acquisition platform was developed to collect the milling process sound through a microphone placed inside the machine-tool enclosure. Data were analysed off-line in order to recognise chatter frequencies.A 3D sound map was built by plotting, on each corresponding point of the mesh described above, the sound amplitude at frequencies around chatter frequency. The difference between stable and unstable zones is shown. This is the stability lobe diagram. The extensive experimentation detailed in this work reasserts and confirms the current state of knowledge of the chatter phenomenon.     

Combined Space Diversity Reception and Trellis Coding for Rayleigh Fading Channels

Space diversity reception, in which several signals received at different antennas are combined, is a well known method that can be used to combat the effects of fading in wireless systems. Also, trellis coded modulation (TCM), when combined with interleaving of sufficient depth, is known to provide some form of time diversity that allows the achievement of good error performance in fading environments. In this paper we consider the analysis of the error performance of reference-based Maximal Ratio Combining (MRC) systems when used in conjunction with trellis-coded MPSK modulation techniques over a Rayleigh fading channel. We also consider the analysis of MRC trellis-coded MPSK systems with conventional differential detection. The results are obtained by using a combination of theoretical analysis and simulation. Exact and near-exact expressions for the pairwise error-event probability in Rayleigh fading are derived. Monte-Carlo simulation results, which are more indicative of the exact system performance, are also given.     

Small-signal modeling of a controlled transformer parallel regulator as a multiple output converter high efficient post-regulator

This paper presents a post-regulator based on the use of a controlled transformer, which adds or subtracts an additional voltage to the output filter of a converter in order to regulate its output voltage. So, their actuation is complementary to that of more known post-regulators, such as the magnetic amplifier (magamp) and synchronous switch post-regulator (SSPR), because the regulation is achieved by controlling the voltage across the filter inductor instead of its charge time. Besides, the post-regulator processes the power in parallel to the one flowing from input to output and only handles a percentage of it. The post-regulation by controlled transformer is suitable of being employed in any isolated PWM power converter and combines a good efficiency and the easiness of design of classical switched power supplies. The work describes the post-regulation strategy for obtaining two outputs independently regulated, and presents a model to obtain the control transfer function and the cross-impedance expressions.     

Species-Specific Cuticular Hydrocarbon Stability within European <Emphasis Type="Italic">Myrmica</Emphasis> Ants

Recognition is a fundamental process on which all subsequent behaviors are based at every organizational level, from the gene up to the super-organism. At the whole organism level, visual recognition is the best understood. However, chemical communication is far more widespread than visual communication, but despite its importance is much less understood. Ants provide an excellent model system for chemical ecology studies as it is well established that compounds known as cuticular hydrocarbons (CHCs) are used as recognition cues in ants. Therefore, stable species-specific odors should exist, irrespective of geographic locality. We tested this hypothesis by comparing the CHC profiles of workers of twelve species of Myrmica ants from four countries across Europe, from Iberia to the Balkans and from the Mediterranean to Fennoscandia. CHCs remained qualitatively stable within each species, right down to the isomer level. Despite the morphological similarity that occurs within the genus Myrmica, their CHCs were highly diverse but remarkably species-specific and stable across wide geographical areas. This indicates a genetic mechanism under strong selection that produces these species-specific chemical profiles, despite each species encountering different environmental conditions across its range.     

RGS5 Determines Neutrophil Migration in the Acute Inflammatory Phase of Bleomycin-Induced Lung Injury

The regulator of G protein signaling (RGS) represents a widespread system of controllers of cellular responses. The activities of the R4 subfamily of RGSs have been elucidated in allergic pulmonary diseases. However, the R4 signaling in other inflammatory lung diseases, with a strong cellular immune response, remained unexplored. Thus, our study aimed to discern the functional relevance of the R4 family member, RGS5, as a potential modulating element in this context. Gene profiling of the R4 subfamily showed increased RGS5 expression in human fibrosing lung disease samples. In line with this, RGS5 was markedly increased in murine lungs following bleomycin injury. RGS knock-out mice (RGS-/-) had preserved lung function while control mice showed significant combined ventilatory disorders three days after bleomycin application as compared to untreated control mice. Loss of RGS5 was associated with a significantly reduced neutrophil influx and tissue myeloperoxidase expression. In the LPS lung injury model, RGS5-/- mice also failed to recruit neutrophils into the lung, which was accompanied by reduced tissue myeloperoxidase levels after 24 h. Our in-vitro assays showed impaired migration of RGS5-/- neutrophils towards chemokines despite preserved Ca²⁺ signaling. ERK dephosphorylation might play a role in reduced neutrophil migration in our model. As a conclusion, loss of RGS5 preserves lung function and attenuates hyperinflammation in the acute phase of bleomycin-induced pulmonary fibrosis and LPS-induced lung injury. Targeting RGS5 might alleviate the severity of exacerbations in interstitial lung diseases.     

Improved loquat (Eriobotrya japonica Lindl.) cultivars: Variation of phenolics and antioxidative potential

Leaves and fruits (peel and flesh) of six improved cultivars (‘Mizuho’, ‘Néctar de Cristal’, ‘Mizauto’, ‘Mizumo’, ‘Centenária’ and ‘NE-3’) of loquat (Eriobotrya japonica Lindl.) were studied for their phenolic composition and antioxidant capacity. The analysis by HPLC-DAD-ESI-MS/MS allowed the identification of 18 compounds (8 hydroxycinnamic acid derivatives and 10 flavonoid glycosides). The quantification of the identified compounds revealed distinct profiles amongst the three analysed materials. Loquat leaves exhibited the lowest amounts of phenolics. 3- And 5-caffeoylquinic, and 5-feruloylquinic acids were the major compounds. Generally, ‘Mizauto’ cultivar presented the highest phenolic content. All loquat materials exhibited DDPH scavenging capacity, in a concentration-dependent manner, the leaves being the most active one. This effect seems to be related to the flavonoid content.