Validation of space-based polarization measurements by use of a single-scattering approximation,with application to the global ozone monitoring experiment

A method is presented for in-flight validation of space-based polarization measurements based on approximation of the direction of polarization of scattered sunlight by the Rayleigh single-scattering value. This approximation is verified by simulations of radiative transfer calculations for various atmospheric conditions. The simulations show locations along an orbit where the scattering geometries are such that the intensities of the parallel and orthogonal polarization components of the light are equal, regardless of the observed atmosphere and surface. The method can be applied to any space-based instrument that measures the polarization of reflected solar light. We successfully applied the method to validate the Global Ozone Monitoring Experiment (GOME) polarization measurements. The error in the GOME's three broadband polarization measurements appears to be approximately 1%.     

Incidence in diverse pig populations of an IGF2 mutation with potential influence on meat quality and quantity: An assay based on real time PCR (RT-PCR)

IGF2, insulin-like growth factor 2, is implicated in myogenesis and lean meat content. A mutation in a single base (A for G substitution) of the gene for IGF2 (position 3072 in intron 3) has been recently described as the cause of a major QTL effect on muscle growth in pigs [Van Laere, A. S, Nguyen, M., Braunschweig, M., Nezer, C., Collete, C., & Moreau, L. et al. (2003). Nature, 425, 832-836]. We describe here a rapid assay based on real time PCR (RT-PCR) to detect this mutation. We have evaluated the incidence of the mutation in commercial pig crosses, in three populations of purebred Iberian or Iberian×Duroc crosses, and in cured meat products and wild boars. The incidence of the mutation varies among these groups. Penetrance of the A mutation is about 80% in the commercial population. Purebred Iberian pigs were all homozygous G/G whereas crosses of Iberian pigs were heterozygous (90%) or homozygous A/A (10%). The implications of this gene for the selection of Iberian pigs are discussed.     

Quantitative analysis in nanoliter wells by prefilling of wells using electrospray deposition followed by sample introduction with a coverslip method

In contrast to performing assays on a substrate using immobilization techniques, wet analysis in nanoliter-sized wells allows quantitative monitoring of enzyme-based reactions by measuring luminescence with time. However, a suitable dispensing method is required to accurately deposit stabilized enzyme solutions into nanoliter wells in such a manner that the enzyme activities are preserved prior to and during measurements. Furthermore, an efficient method is required to add sample liquid to these wells in such a manner that evaporation of assay liquid is completely prevented during sample introduction and monitoring. A powerful methodology is presented in this paper allowing quantitative analysis of enzyme-based reactions in identical nanoliter volumes on-chip. In a first step, picoliter amounts of protein solutions are deposited as uniform dry dots into wells using our reported electrospraying technique (Moerman, R.; Frank, J.; Marijnissen, J. C. M.; Schalkhammer, T. G. M.; van Dedem, G. W. K. Anal. Chem. 2001, 73, 2183-2189.). The silicon chips are then stored at temperatures as low as -80 degrees C. At the time of analysis, a sample solution is slid into the wells using a coverslip. With the edge of the coverslip, sample solution is pushed across the wells at a speed of 1.5-2.5 cm/s to prevent carryover of reagents to neighboring wells. Evaporation of assay liquid from the wells is prevented because the coverslip seals the wells and "bonds" to the chip by adhesion forces. Electrospraying appears to be an excellent method to deposit enzyme solutions containing up to 20% (w/v) of trehalose without being hampered by clogging of the capillary or splashing of droplets. After being sprayed on-chip (silicon nitride), the enzymes pyruvate kinase and lactate dehydrogenase remained stable for a period of 1.5-2 months at a storage temperature of -20 degrees C. The coverslip method completely prevented evaporation for minutes up to hours allowing monitoring of enzyme-based reactions in arrays of nanoliter wells.     

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.