Ultra Wide Band WLANs: A Self-Configuring Resource Control Scheme for Accessing UWB Hot-Spots with QoS Guarantees

In the framework of wireless access networks the Hot-Spot concept is attracting several operators. In a Hot-Spot near stationary terminals may reach one or more Radio Access Points (RAP) offering wireless access to the fixed network. Mobile terminals should be able to register to the network, associate to a RAP and activate a wireless communication supporting given bit rates and Quality of Service (QoS) features. Several mobile users, requiring different services, enter and exit the Hot-Spot. In this scenario network operators should have the opportunity to configure quickly radio resources to serve the mobile terminals and to handle efficiently the network resources in order to maximize the income. Among the different technologies emerging in this field, we investigate the feasibility of a wireless access based on Ultra Wide Band (UWB) radio, combined with a flexible admission control scheme based on transmission power selection. We employ UWB in unlicensed mode, i.e., we operate in accordance to the limits imposed by the regulatory bodies (e.g., US Federal Communications Commission). The flexibility of the admission control depends mainly on the capability of a mobile terminal of “measuring” the environment it is entering and thus supporting the RAP in the selection of the appropriate transmission parameters. The proposed approach provides an admission policy based on the Maximum Extra Interference (MEI) and selects the power level through a simple interaction among the involved mobile terminals. The information for basing the decision on is collected through measurements and signaling. In order to increase the system efficiency, transmission parameters are selected in accordance to a “balancing” criterion (thus Balanced-MEI, B-MEI). The B-MEI approach keeps quite simple the admission of new mobile terminals in a RAP’s area but contemporarily satisfies the trade-off between fair resource assignment and system efficiency. This is a key trade-off in wireless access systems where interference effects determine the upper limit of the number of users that can be admitted in the network.Francesca Cuomo received her “Laurea” degree in Electrical and Electronic Engineering in 1993, magna cum laude, from the University of Rome “La Sapienza”, Italy. She earned the Ph.D. degree in Information and Communications Engineering in 1998, also from the University of Rome “La Sapienza.” Since 1996 she is an Assistant Professor at the INFOCOM Department of this University. Her main research interests focus on broadband integrated networks, Intelligent Networks, architectures and protocol for wireless networks, mobile and personal communications, Quality of Service guarantees and real time service support in the wired and wireless Internet.She participated in: (I) the European ACTS INSIGNIA project dedicated to the definition of an Integrated IN and B-ISDN network; (III) IST WHYLESS.COM project focusing on adoption of the Ultra Wide Band radio technology for the definition of an Open Mobile Access Network; (III) RAMON project, funded by the Italian Public Education Ministry, focused on the definition of a reconfigurable access module for mobile computing applications. She is now participating to the European IST ePerSpace Project focusing on the support of personalized audio/video services at home and everywhere. She is also involved in FIRB project VIRTUAL IMMERSIVE COMMUNICATIONS (VICOM) where she is responsible of the research activities on the BAN and PAN networks.Dr. Cuomo is in the editorial board of the Elsevier Computer Networks journal and she has served on technical program committees and reviewer in several international conferences and journals including ACM Wireless Mobile Internet Workshop, IEEE ICC and GLOBECOM, IEEE Trans. on Wireless Communications and IEEE Journal on Selected Areas on Communications.Cristina Martello received her Laurea degree in Electronic Engineering (magna cum laude) in July 2000 from Università di Roma “La Sapienza”. She earned the PhD degree in Information and Communications Engineering in February 2004 (Università di Roma “La Sapienza”).Since January 2001 she has been working in the IST European HYPERLINK “/” “_blank” Whyless.com project on an open mobile access network based on the Ultra Wide Band radio technology. She collaborated with HYPERLINK “http://www.coritel.it/” “_blank” Co.Ri.Tel. (a research consortium on Telecommunications) as a fellowship holder in 2000/2001 for the project SWAP on the feasibility of a re-configurable software module for the dynamic Radio Resource Control in the 3G of mobile wireless systems, and in 2002 for the project PRESTO.Her main research interests regard the developing of flexible and distributed Radio Resource Control techniques for “ad-hoc like” networking paradigms.     

Extracts of Haematoxylon brasiletto inhibit growth, verotoxin production, and adhesion of enterohemorrhagic Escherichia coli O157:H7 to HeLa cells

The extracts of 33 plants were evaluated for their effects on growth of Escherichia coli O157:H7 (EHEC). The extract of Haematoxylon brasiletto was the only one that effectively inhibited bacterial growth. The effects of ethanolic extracts of this plant on growth, verotoxin production, and adhesion of E. coli O157:H7 to HeLa cells were determined. The MBC for growth was 4 mg/ml. No verotoxin formation was detected at 1, 2, or 3 mg/ml. Preexposing bacteria and HeLa cells to various concentrations of extracts affected the adhesion between non-EHEC and HeLa cells. Partial purification of the active fraction suggested that polyphenols might play a role in the antimicrobial activity exhibited by H. brasiletto extracts.     

Experimental and predicted enthalpies of mixing of mixtures formed from alcohols and sunflower oil at 298.15 K

The enthalpies of mixing of systems formed from alcohols (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and 2-butanol) and sunflower oil at 298.15 K are presented. Enthalpies were measured in the composition range in which the compounds were miscible. From the experimental measurements, we calculated the heat capacities of the mixtures. Several group contribution models were applied to estimate the enthalpies of mixing of these mixtures. The average deviations varied from 10 to 60%, depending on the model and compound. The best prediction in all cases was the Nitta model, with average deviations from 10 to 30%. The novelty of the work is that models of this type have not been applied previously to predict enthalpies of such large molecules, and the results of the estimates are of the same order as other types of compounds (pure compounds of small size).     

Precatalyst separation paradigms: alkane functionalization in water utilizing in situ formed [Fe2O(η1-H2O)(η1-OAc)(TPA)2]3+, embedded in surface-derivatized silica, as an MMO model, and fluorous biphasic catalysis for alkane, alkene, and alcohol oxidation chemistry

Two precatalyst separation paradigms will be reviewed. The first involves the biomimetic, methane monoxygenase enzyme (MMO) precatalyst, [Fe₂O(¹-H₂O)(¹-OAc)(TPA)₂]³⁺ (TPA=tris[(2-pyridyl)methyl]amine), 1 , formed in situ at pH 4.2 from [Fe₂O(-OAc)(TPA)₂]³⁺, 2 , which was embedded in an amorphous silicate surface modified by a combination of hydrophilic polyethylene oxide and hydrophobic polypropylene oxide, for ease of separation from the products formed. The resulting catalytic assembly was found to be a biomimetic model for the MMO active site within a hydrophobic macroenvironment, allowing alkane functionalization with t- butyl hydroperoxide (TBHP)/O₂ in an aqueous reaction medium (pH 4.2). For example, cyclohexane was oxidized to a mixture of cyclohexanone, cyclohexanol, and cyclohexyl-t -butyl peroxide, in a ratio of ~3:1:2. The balance between polyethylene oxide and polypropylene oxide, tethered on the silica surface, was crucial for maximizing the catalytic activity. Moreover, the mechanism for the silica-based catalytic assembly was found to occur via the Haber–Weiss process. The second precatalyst separation paradigm, the use of the fluorous solvents, which is predicated on solubilizing the precatalyst in a fluorocarbon solution, allows the functionalization of alkanes and alkenes, while selective oxidation of alcohols to aldehydes was also possible; both precatalyst and product are in separate solvent phases. A discussion concerning both separation of precatalyst from product approaches will be presented.     

Acoustic emission events from sodium vapour bubble collapsing: A stochastic model

The forward Kolmogorov equation method has been applied to a zero-dimensional model which describes the time distribution of acoustic emissions from sodium vapour bubble collapsing.Processes taken into account as components for outlining the upstated phenomenon are: energy generation, energy dissipation, bubble creation, acoustic emission and energy release from bubble collapsing.Processes involve affect or are induced by a population of particles (bubbles, acoustic pulses) and pseudoparticles (energetic units).A formulation is obtained for the expected values of some stochastic indicators, i.e. factorial moments and cumulants, autocorrelation function, waiting time distribution between contiguous events, of the time series consisting of acoustic emission pulses as detected by a suitable sensor.Preliminary but promising validation of the model and a sound prelude to an effective boiling regime diagnosing is obtained by processing data from the out-of-pile CFNa loop in Grenoble, France. Data are collected from a piezoelectric accelerometer located nearby the circuit.     

Structural analysis of glucoamylase encoded by the STA1 gene of Saccharomyces cerevisiae (var. diastaticus)

The sequence of the STA1-encoded glucoamylase of amylolytic Saccharomyces cerevisiae (var. diastaticus) strains shows two well-defined regions: an amino-terminal part rich in serine and threonine residues and a carboxy-terminal part very similar to the catalytic domain of other fungal glucoamylases. A version of the enzyme in which most of the amino-terminal region was deleted still has glucoamylase activity, indicating that the remaining carboxy-terminal part forms a functional catalytic domain. Homology-based models of the two parts of the protein have been obtained. As expected, the shortened form of the enzyme is very similar to the catalytic domain of related glucoamylases of known structure. However, the amino-terminal part yielded a structure revealing an unexpected similarity to bacterial invasins, suggesting functional connections between several yeast proteins homologous to STA1-encoded glucoamylase and invasins. A characteristic of Saccharomyces glucoamylase in its native form is its extreme degree of glycosylation. Despite its high molecular mass (about 300 kDa), and in contrast with what occurs with other extracellular glycoproteins produced by yeast, the enzyme does not remain attached to the cell wall, being fully and efficiently secreted into the medium, even when it is produced in large amounts by overexpression of its gene.     

Optical-sectioning improvement in two-color excitation scanning microscopy

We present a new beam-shaping technique for two-color excitation fluorescence microscopy. We show that by simply inserting a properly designed shaded-ring filter in the illumination beam of smaller wavelength, it is possible to improve the effective optical sectioning capacity of such microscopes by 23%. Such an improvement is obtained at the expense of only a very small increasing of the overall energy in the point-spread-function sidelobes. The performance of this technique is illustrated by a numerical imaging simulation.     

Excess molar volumes and refractive indices of mixtures formed by acetates with sunflower oil at different temperatures

The aim of this work is to measure the densities and refractive indices of mixtures formed of acetates (ethyl, vinyl, propyl, isopropyl, and butyl acetate) with sunflower oil. From these measurements, excess molar volumes and variations of the refractive index of the mixtures have been calculated. The properties were measured at temperatures varying from 288.15 to 298.15 K. The excess molar volumes and variations of refractive index data were correlated vs. composition with Redlich-Kister polynomials. Densities of the mixtures were predicted by the Rackett and modified Rackett equations. Refractive indices of the mixtures were predicted by several mixing rules and compared with experimental values. In all cases, SD between predicted and experimental data were less than 5%.     

Synthesis of Poly(DL-Lactide-Co-Glycolide) Nanoparticles with Entrapped Magnetite by Emulsion Evaporation Method

The goal of this study was to synthesize Poly(DL-lactide-Co-glycolide) nanoparticles with entrapped magnetite, of under 100 nm in diameter, for future drug delivery applications. The emulsion evaporation method was selected to form poly(lactide-co-glycolide) (PLGA) nanoparticles with entrapped magnetite (Fe₃O₄) in the polymeric matrix, in the presence of sodium dodecyl sulfate (SDS) as a surfactant. Magnetite, a water-soluble compound, was surface functionalized with oleic acid to ensure its efficient entrapment in the PLGA matrix. The inclusion of magnetite with oleic acid (MOA) into the PLGA nanoparticles was accomplished in the organic phase. Synthesis was followed by dialysis, performed to eliminate the excess SDS, and lyophilization. The synthesized nanoparticles ranged in size from 38.6 to 67.1 nm for naked PLGA nanospheres and from 78.8 to 87.2 nm for MOA-entrapped PLGA nanospheres. The entrapment efficiency ranged from 57.36% to 77.3%.     

Fiber orientation in divergent/convergent flows in expansion and compression injection molding

This study compares the fiber orientation patterns of short glass fiber‐reinforced polypropylene developed in conventional and nonconventional injection molding, the latter using a special mold, RCEM (rotation, compression, and expansion mold). This mold allows for a wide variety of operating modes during mold filling, which leads to a great versatility in obtaining different fiber orientation patterns. By incorporating through‐thickness convergent and divergent flows during the filling stage (compression and expansion modes, respectively), the fiber orientation can be tailored. These linear dynamics can be superimposed with a simultaneous rotational movement of one of the mold surfaces. These combined actions induce a high fiber orientation transversely to the radial flow direction, this effect being more pronounced in the expansion mode. POLYM. COMPOS. 27:539–551, 2006. © 2006 Society of Plastics Engineers