Invertase activity in fresh and processed honeys

The enzymatic activities of 147 samples of commercially produced Spanish polyfloral and monofloral honeys are reported. Important variations in invertase activity and peroxide accumulation were determined to obtain objective information related to honey quality. Variations from 4.04 (Robinia pseudoacacia) to 25.61 g sucrose hydrolysed per 100 g h⁻¹ (SN) (Castanea sativa) and from 11.31 (Erica vagans) to 45.25 µg H₂O₂ g⁻¹ h⁻¹ (Hedysarum coronarium) were detected, with a range from 10.57 to 46.2 SN in polyfloral honeys. Honeys from Erica spp had different invertase activities—high for E cinerea (18.3 SN) and low for E vagans (8.36 SN). The different heating processes of honey have been evaluated to determine the best treatment for preserving invertase activity. The hydroxymethylfurfural content is not a sufficiently good indicator of the degree of deterioration of honey. Another objective was to assess the use of invertase activity in honey quality legislation. © 2000 Society of Chemical Industry     

Analytical Analysis of Bayesian CramÉr–Rao Bound for Dynamical Rayleigh Channel Complex Gains Estimation in OFDM System

In this paper, we consider the Bayesian Cramer-Rao bound (BCRB) for the dynamical estimation of multipath Rayleigh channel complex gains in data-aided (DA) and non-data-aided (NDA) OFDM systems. This bound is derived in an online and offline scenarios for time-invariant and time-varying complex gains within one OFDM symbol, assuming the availability of prior information. In NDA context, whereas this true BCRB is hard to evaluate, we present a closed-form expression of a BCRB, i.e., the asymptotic BCRB (ABCRB) or the modified BCRB (MBCRB). We discuss, based on the theoretical and simulation results, the interest of using some past and future observations in terms of Doppler spread for the complex gains estimation.     

CMOS-SOI platform for monolithic integration of crystalline silicon MEMS

A new platform for the fabrication of crystalline micro- and nano-electromechanical systems fully integrable with CMOS is presented. A pre-CMOS process on SOI wafers allows bulk silicon areas for standard CMOS processing and areas with a stack layer of silicon and silicon oxide to be obtained, in which a set of microelectromechanical devices can be fabricated. An integrated resonant beam system with electrical actuation and detection fabricated according to the presented approach is provided.     

Bandwidth sharing under the assured forwarding Per-Hop behavior

The DiffServ’s Assured Forwarding (af) Per-Hop Behavior (phb) Group defines a differentiated forwarding of packets in four independent classes, each class having three levels of drop precedence. Specific end-to-end services based on thisphb are still being defined. A particular type of service that could assure a given rate to a traffic aggregate has been outlined elsewhere. In such a service, a fair distribution of bandwidth is one of the main concerns. This paper presents experimental work carried out to evaluate howaf distributes bandwidth among flows under different load conditions and traffic patterns. We focused on the effect that marking mechanisms have on bandwidth sharing among flows within a singleaf class. The traffic types we used includeudp flows, individual and aggregatedtcp flows, mix oftcp andudp, tcp sessions with heterogeneous round-trip times, as well as color-blind and color-aware re-marking at the aggregation point fortcp flows. Tests were performed on real and simulated networks. We have found certain conditions under whichaf distributes bandwidth fairly among nonadaptiveudp flows andtcp aggregates. Finally, we evaluate a basic rule for setting the parameters of the two-rate Three-Color Marker conditioning algorithm (trtcm) in order to achieve a better bandwidth distribution fortcp flows.     

Loss characterization in high-speed networks through simulation of fluid models

This paper describes the design principles of a fluid-based, discrete-event simulator and its application to the characterization of losses in ATM networks. This simulation technique allows us to obtain performance measures that either cannot be found using known analytical methods or for which a conventional simulation is too expensive; notably, fluid-model simulation makes it feasible to characterize for a given buffer its occupation, duration of congestion periods, frequency of loss bursts and loss-burst volume in fairly complex networks. Several numerical examples illustrate the proposed simulation method.     

On-Line Competitive Algorithms for Call Admission in Optical Networks

We study the on-line call admission problem in optical networks. We present a general technique that allows us to reduce the problem of call admission and wavelength selection to the call admission problem. We then give randomized algorithms with logarithmic competitive ratios for specific topologies in switchless and reconfigurable optical networks. We conclude by considering full duplex communications. Received August 16, 1997; revised May 11, 1998.     

Methodological quality in clinical trials and bibliometric indicators: no evidence of correlations

Citation frequencies and journal impact factors (JIFs) are being used more and more to assess the quality of research and allocate research resources. If these bibliometric indicators are not an adequate predictor of research quality, there could be severe negative consequences for research. To analyse to which extent citation frequencies and journal impact factors correlate with the methodological quality of clinical research articles included in an SBU systematic review of antibiotic prophylaxis in surgery. All 212 eligible original articles were extracted from the SBU systematic review “Antibiotic Prophylaxis in Surgery” and categorized according to their methodological rigourness as high, moderate or low quality articles. Median of citation frequencies and JIFs were compared between the methodological quality groups using Kruskal–Wallis non-parametric test. An in-depth study of low-quality studies with higher citation frequencies/JIFs was also conducted. No significant differences were found in median citation frequencies (p = 0.453) or JIFs (p = 0.185) between the three quality groups. Studies that had high citation frequencies/JIFs but were assessed as low-quality lacked control groups, had high dropout rates or low internal validity. This study of antibiotic prophylaxis in surgery does not support the hypothesis that bibliometric indicators are a valid instrument for assessing methodological quality in clinical trials. This is a worrying observation, since bibliometric indicators have a major influence on research funding. However, further studies in other areas are needed.     

Lessening polygalacturonase activity in a commercial enzyme preparation by exposure to pulsed electric fields

The effect of high-intensity pulsed electric field (HIPEF) treatments on polygalacturonase (PG) activity in an aqueous solution of a commercial enzyme preparation was evaluated. HIPEF treatments reduced PG activity notably. Exponentially decaying pulses of 40 and 160 µs generated by a laboratory scale device were applied in a batch processing and bipolar mode. Electric fields ranged from 5.18 to 19.39 kV/cm. The number of pulses ranged up to 400. Temperature was always below 25 °C. Maximum inactivation of PG activity (98%) required 32.4 ms HIPEF treatment at 10.28 kV/cm. PG activity depleted exponentially because of HIPEF treatments. The first order rate constants ranged from 32 to 590 µs ^-1 and increased exponentially with electric field intensity. PG activity decreased exponentially with input electric energy density.     

Infusion and decoction of wild German chamomile: Bioactivity and characterization of organic acids and phenolic compounds

Natural products represent a rich source of biologically active compounds and are an example of molecular diversity, with recognised potential in drug discovery. Herein, the methanol extract of Matricaria recutita L. (German chamomile) and its decoction and infusion (the most consumed preparations of this herb) were submitted to an analysis of phytochemicals and bioactivity evaluation. The antioxidant activity was determined by free radicals scavenging activity, reducing power and inhibition of lipid peroxidation; the antitumour potential was tested in human tumour cell lines (breast, lung, colon, cervical and hepatocellular carcinomas), and the hepatotoxicity was evaluated using a porcine liver primary cell culture (non-tumour cells). All the samples revealed antioxidant properties. The decoction exhibited no antitumour activity (GI₅₀ > 400 μg/mL) which could indicate that this bioactivity might be related to compounds (including phenolic compounds) that were not extracted or that were affected by the decoction procedure. Both plant methanol extract and infusion showed inhibitory activity to the growth of HCT-15 (GI₅₀ 250.24 and 298.23 μg/mL, respectively) and HeLa (GI₅₀ 259.36 and 277.67 μg/mL, respectively) cell lines, without hepatotoxicity (GI₅₀ > 400 μg/mL). Infusion and decoction gave higher contents of organic acids (24.42 and 23.35 g/100 g dw). Otherwise, the plant methanol extract contained the highest amounts of both phenolic acids (3.99 g/100 g dw) and flavonoids (2.59 g/100 g dw). The major compound found in all the preparations was luteolin O-acylhexoside. Overall, German chamomile contains important phytochemicals with bioactive properties (mainly antitumour potential selective to colon and cervical carcinoma cell lines) to be explored in the pharmaceutical, food and cosmetics industries.     

Synthesis of Fatty Acid Amides of Catechol Metabolites that Exhibit Antiobesity Properties

A series of fatty acid amides of 3,4‐methylenedioxymethamphetamine (MDMA) catechol metabolites were synthesized in order to evaluate their biological activities. Upon administration, all synthesized compounds resulted in negative modulation of food intake in rats. The most active compounds have affinity for the CB₁ receptor and/or PPAR‐α; part of their biological activity may be caused by these double interactions.