Search

The influence of humidity on streamer propagation at conditions from the threshold for propagation to those for streamer-induced breakdown was investigated in a uniform field in air at atmospheric pressure. Experiments were carried out in a three electrode arrangement consisting of a 12 cm long parallel-plane gap, with an auxiliary needle in the earthed anode. Positive streamers were initiated by applying at the needle electrode a pulse voltage which varied in amplitude. These propagated towards the upper plane electrode which was stressed by a negative dc voltage. Under natural atmospheric conditions, propagation and breakdown probability curves were obtained for several values of absolute humidity in the range between 5 and 22 g/m3. Thus, distributions of the electric field required for streamer propagation and breakdown were obtained and the associated velocity of propagation and time to breakdown were measured. Besides humidity, the amplitude of the voltage used for streamer initiation and the ambient electric field were considered as influencing parameters on streamer properties. Empirical equations are presented expressing the effects of the above parameters on the intrinsic streamer properties. A comparison with previous work in the literature is made and this leads to the conclusion that the influence of humidity on streamer propagation and breakdown can be placed in a sounder quantitative basis. [ABSTRACT FROM AUTHOR]

The LIULIN-3M instrument is a further development of the LIULIN dosimeter-radiometer, used on the MIR space station during the 1988–1994 time period. The LIULIN-3M is designed for continuous monitoring of the radiation environment during the BION-12 satellite flight in 1999. A semiconductor detector with 1 mm thickness and 1 cm2 area is contained in the instrument. Pulse high analysis technique is used to determine the energy losses in the detector. The final data from the instrument are the flux and the dose rate for the exposure time and 256 channels of absorbed dose spectra based on the assumption that the particle flux is normal to the detector. The LIULIN-3M instrument was calibrated by proton fluxes with different energies at the Indiana University Cyclotron Facility in June 1997 and had been used for radiation measurements during commercial aircraft flights. The calibration procedure and some flight results are presented in this paper. [Copyright &y& Elsevier]

Studies the solution structure of the complex between an analog of the bulge-specific cleaving species and an oligodeoxynucleotide containing a two-base bulge. Cleavage targets for the enediyne antitumor antibiotic neocarzinostatin chromophore; Design of bulge-specific nucleic acid binding molecules.

In the rapidly emerging field of biomedical applications, multifunctional nanoparticles, especially those containing magnetic and plasmonic components, have gained significant attention due to their combined properties. These hybrid systems, often composed of iron oxide and gold, provide both magnetic and optical functionalities and offer promising avenues for applications in multimodal bioimaging, hyperthermal therapies, and magnetically driven selective delivery. This paper focuses on the implementation of advanced characterization methods, comparing statistical analyses of individual multifunctional particle properties with macroscopic properties as a way of fine-tuning synthetic methodologies for their fabrication methods. Special emphasis is placed on the size-dependent properties, biocompatibility, and challenges that can arise from this versatile nanometric system. In order to ensure the quality and applicability of these particles, various novel methods for characterizing the magnetic gold particles, including the analysis of their morphology, optical response, and magnetic response, are also discussed, with the overall goal of optimizing the fabrication of this complex system and thus enhancing its potential as a preferred diagnostic agent. [ABSTRACT FROM AUTHOR]

We examine the automatic configuration of consumer electronics devices delivering remote services to the home network. This environment has two particular aspects; it addresses a mass market, hence any automated approach for streamlined deployment, operation and scalability is of prime importance; it also relies on standardization due to its high dependency on communication protocols and services. Modern standards in this domain, along with the invocation of state of the art technologies around XML, give a totally new look at old management problems. More importantly, these standards directly and primarily address configuration issues in a structured and comprehensive way. This paper promotes the view that these standardizations work, pursued and presented in text form by the relevant standardization bodies. It also suggests standard-based methodologies and tools for remote configuration, management, life-cycle support and testing of devices. This inherently ensures compliance to the standards and enables a streamlined design, thus facilitating the provisioning and management of services offered to subscribers. Our contribution concerns relevant tool suites covering to some variable extend all of these aspects. We emphasize the logical succession of each consecutive step/tool and draw attention to the fact that the resulting interrelationships originate from a common source (i.e. the TR-069 standard) and reflect generic needs of the user/player in question. [ABSTRACT FROM AUTHOR]

XML technology is penetrating network management in the IETF, UPnP, and DSL Forum suite of standards and protocols. The advantages of XML are offered at the cost of long byte streams due to XML's inherently verbose nature, The increase in packet size for remote configuration and management can pose problems, if executed in a point-to-multipoint arrangement comprising one automatic configuration server and thousands of home gateways and multimedia devices. We investigate and exploit the repetitive nature of text patterns in typical XML documents as produced by the configuration and management tasks and as coded in SOAP RPCs. The solution mainly comes from application of the Lempel-Ziv compression algorithm, with minimal additions in the proposed DSL Forum standard. Numerical and experimental results support the applicability and advantages of the proposed approach and provide insight on how these are attributable to different layers of the employed protocol stack. [ABSTRACT FROM AUTHOR]

Summary The mglA gene encodes a 22 kDa GTPase that is critical for single-cell (A) gliding, type IV pili-mediated (S) gliding and development of Myxococcus xanthus . To identify components that interact with MglA to control these processes, second-site mutations that restore movement to non-motile mglA mutants were sought. An allele-specific extragenic suppressor of mglA8 , named mas815 (mglA8 s uppressor 15), was obtained. mas815 does not bypass the requirement for MglA, yet it restores type IV pili-mediated motility and starvation-induced development. Single-cell (A) motility is not restored. The suppressing mutation maps to the 3′ end of a gene, masK , in an operon immediately upstream of the mglBA operon. masK encodes a protein of the STY kinase family. When the masK gene was used as bait against a library carrying M. xanthus DNA in the yeast two-hybrid system, eight positive, independent clones containing fusions of mglA to GAL4 were obtained, thus confirming the interaction between MglA and MasK. MasK, expressed in Escherichia coli , was shown to phosphorylate at a tyrosine residue(s). The gain-of-function in the masK815 mutant was correlated with increased production of extracellular fibrils, which are required for adhesion, cell–cell contact and sensing phosphatidylethanolamine chemoattractants. These data suggest that the interaction between MasK and MglA is an essential part of a signal transduction pathway controlling motility and development. [ABSTRACT FROM AUTHOR]

During a series of presentations of scientific papers 40.6% of 276 subjects reported dreaming, but only 18.1% actually fell asleep. The frequency of dreaming was significantly increased by the addition of either "very boring" or "very interesting" slides to the usual ones, but not by "neutral" slides. The recall of lecture content and the proportion of audience asleep were (surprisingly) not greatly affected by the addition of extraneous slides of any sort. On the other hand, adding "very interesting" slides greatly increases audience enjoyment. [ABSTRACT FROM PUBLISHER]

Background Herpes zoster (HZ) develops in up to 50% of unvaccinated individuals, accounting for >1 million cases annually in the United States. A live attenuated HZ vaccine (LAV) is Food and Drug Administration approved for those age 50 years or older, though Advisory Committee on Immunization Practices recommendations are only for those age 60 years or older. LAV efficacy is ~70% for persons 50–59 years of age, with lower efficacy in older adults. A new 2-dose adjuvanted subunit vaccine (SUV) has >95% efficacy in persons 50–69 years of age and remains ~90% efficacious in persons vaccinated at age 70 years. Methods To estimate the relative cost-effectiveness of SUV, LAV, and no vaccination (NoV) strategies, a Markov model was developed based on published data on vaccine efficacy, durability of protection, quality of life, resource utilization, costs, and disease epidemiology. The perspective was US societal, and the cycle length was 1 year with a lifelong time horizon. SUV efficacy was estimated to wane at the same rate as LAV. Outcomes evaluated included lifetime costs, discounted life expectancy, and incremental cost-effectiveness ratios (ICERs). Results For individuals vaccinated at age 50 years, the ICER for LAV vs NoV was $118 535 per quality-adjusted life-year (QALY); at age 60 years, the ICER dropped to $42 712/QALY. SUV was more expensive but had better ICERs than LAV. At age 50, the ICER was $91 156/QALY, and it dropped to $19 300/QALY at age 60. Conclusions Vaccination with SUV was more cost-effective than LAV in all age groups studied. Vaccination with SUV at age 50 years appears cost-effective, with an ICER <$100 000/QALY. [ABSTRACT FROM AUTHOR]

This paper proves that voice over Internet protocol (IP) technology can be combined with satellite transmission in air traffic control (ATC) applications provided that the systems used to implement this approach have been meticulously designed to meet the end-to-end delay requirements and to certify the quality of service they offer under strenuous conditions.We propose a modified E-model and prove it can be used as a radio network planning tool, because once the requirements that were drawn from it were fulfilled, the users of the resulting service accepted it as sufficient in terms of call quality. The approach has been applied on the SATWAYS system, cofunded by the European Space Agency, and designed and implemented to extend the coverage of radio frequencies within airspaces when the commonly used landline communication infrastructure is either too costly or impossible to install and maintain. The paper provides evidence that the way to an all-IP ATC network is wide open. [ABSTRACT FROM AUTHOR]

The impulse behavior of composite short rod-plane air gaps with a dielectric-covered rod under positive lightning and switching impulse voltages is investigated, by monitoring the electric field strength at the earthed plane, by still photographs of corona discharges and through electric field computations. Experiments were performed in normal laboratory air at pressure around 0.1 MPa, temperatures in the range 19 to 28°C and absolute and relative humidity varied naturally between 11-21 g/m3 and 60-90%, respectively. Breakdown probability distributions were obtained for composite gaps with a dielectric cover made of either PTFE or epoxy resin and for simple air gaps with a bare rod. Also, basic characteristic parameters of coronas preceding breakdown in composite gaps, namely initial corona in the vicinity of the covering tip, surface coronas emerging along the dielectric cover and developing mainly in air, and secondary corona in the vicinity of the cover upper end, were measured. Surface corona development is greatly affected by initial corona growth and facilitates secondary corona inception. Breakdown, occurring at higher voltages for composite gaps, is closely related with the secondary corona inception; a similar dependence upon impulse waveshape and cover material was seen to exist. At breakdown, the spark channel bridges the gap that includes the dielectric cover length. The spark channel develops either along the cover surface or partly or solely in free air, being affected by surface corona development. [ABSTRACT FROM AUTHOR]

Giving the operator the ability to manage in-home devices greatly increases the potential of the cost-efficient provision of new profitable services. In this spirit, standardization undertaken by the DSL forum not only addresses remote management of the residential gateway but recently, also extends to in-house devices. We propose a solution that bridges remote management specified by CWMP with UPnP, already established inside the home environment. This approach will enable providers to remotely configure and manage in-house UPnP-enabled equipment, thus accelerating the deployment of new services. We investigate the nature of the two protocols and specify the bridging functionality, taking into consideration scalability and transparency. Experimental results support the applicability of the proposed approach, highlight the importance of message filtering, and provide general insight into the interplay intricacies of the particular protocol functions. [ABSTRACT FROM AUTHOR]

Background. In evaluating a photochemical treatment process for inactivating parvovirus B19, there lacked simple culture methods to measure infectivity. The recently developed enzyme-linked immunospot (ELISpot) infectivity assay uses late-stage erythropoietic progenitor cells and is labor intensive and time consuming. We evaluated a novel, efficient polymerase chain reaction (PCR) inhibition assay and examined correlations with reductions in infectivity. Methods. Contaminated plasma was treated with 150 μmol/L amotosalen and 3 J/cm² ultraviolet A light and then tested for DNA modification using conventional PCR inhibition and a novel preamplification approach. The novel assay subjected the samples to preamplification cycles using long-template PCR, followed by quantitative PCR (QPCR) inhibition detection. Both approaches were tested for correlations with reductions in viral infectivity by comparing ELISpot assay results of identical samples. Results. The B19 preamplification inhibition assay showed detection ranges of 2–2.5 log and demonstrated quantitative correlation with up to a 5.8-log reduction in viral infectivity in ELISpot results. Conventional PCR detected a >5 log reduction in amplification, correlated with a 4.4-log reduction in viral infectivity. A ange of 4-log inhibition of hepatitis B virus DNA amplification was also achieved. Conclusions. The results demonstrated that a novel preamplification QPCR assay is a useful tool for predicting reductions in infectivity after photochemical treatment. This assay was extended to show utility in circumstances where practical in vitro assays are unavailable for the determination of the efficacy of pathogen inactivation. [ABSTRACT FROM AUTHOR]

We developed a new class of vaccines, based on killed but metabolically active (KBMA) bacteria, that simultaneously takes advantage of the potency of live vaccines and the safety of killed vaccines. We removed genes required for nucleotide excision repair (uvrAB), rendering microbial-based vaccines exquisitely sensitive to photochemical inactivation with psoralen and long-wavelength ultraviolet light. Colony formation of the nucleotide excision repair mutants was blocked by infrequent, randomly distributed psoralen crosslinks, but the bacterial population was able to express its genes, synthesize and secrete proteins. Using the intracellular pathogen Listeria monocytogenes as a model platform, recombinant psoralen-inactivated Lm ΔuvrAB vaccines induced potent CD4+ and CD8+ T-cell responses and protected mice against virus challenge in an infectious disease model and provided therapeutic benefit in a mouse cancer model. Microbial KBMA vaccines used either as a recombinant vaccine platform or as a modified form of the pathogen itself may have broad use for the treatment of infectious disease and cancer. [ABSTRACT FROM AUTHOR]

The aglZ gene of Myxococcus xanthus was identified from a yeast two-hybrid assay in which MglA was used as bait. MglA is a 22-kDa cytoplasmic GTPase required for both adventurous and social gliding motility and sporulation. Genetic studies showed that aglZ is part of the A motility system, because disruption or deletion of ag1Z abolished movement of isolated cells and aglZ sglK double mutants were nonmotile. The aglZ gene encodes a 153-kDa protein that interacts with purified MglA in vitro. The N terminus of AglZ shows similarity to the receiver domain of two-component response regulator proteins, while the C terminus contains heptad repeats characteristic of coiled-coil proteins, such as myosin. Consistent with this motif, expression of AglZ in Escherichia coli resulted in production of striated lattice structures. Similar to the myosin heavy chain, the purified C-terminal coiled-coil domain of AglZ forms filament structures in vitro. [ABSTRACT FROM AUTHOR]