Application of a Diffusion Charger for the Measurement of Particle Surface Concentration in Different Environments

Particle surface area has recently been considered as a possible metric in an attempt to correlate particle characteristics with health effects. In order to provide input to such studies, two Nanoparticle Surface Area Monitors (NSAMs, TSI, Inc.) were deployed in different urban sites within Los Angeles to measure the concentration levels and the diurnal profiles of the surface area of ambient particles. The NSAM's principle of operation is based on the unipolar diffusion charging of particles. Results show that the particle surface concentration decreases from ～150 μ m² cm^?3 next to a freeway to ～ 100 μ m² cm^?3 at 100 m downwind of the freeway, and levels decline to 50–70 μ m² cm^?3 at urban background sites. Up to 51% and 30% of the total surface area corresponded to particles < 40 nm next to the freeway and at an urban background site, respectively. The NSAM signal was well correlated with a reconstructed surface concentration based on the particle number size distribution measured with collocated Scanning Mobility Particle Sizers (SMPSs, TSI, Inc.). In addition, the mean surface diameter calculated by combination of the NSAM and the total particle number concentration measured by a Condensation Particle Counter (CPC, TSI, Inc.) was in reasonable agreement with the arithmetic mean SMPS diameter, especially at the urban site. This study corroborates earlier findings on the application of diffusion chargers for ambient particle monitoring by demonstrating that they can be effectively used to monitor the particle surface concentration, or combined with a CPC to derive the mean surface diameter with high temporal resolution.     

Prebiotic potential of barley derived β-glucan at low intake levels: A randomised,double-blinded,placebo-controlled clinical study

This randomised, double-blinded, placebo-controlled clinical study aimed to evaluate the in vivo prebiotic potential of barley β-glucan. Fifty-two healthy volunteers aged 39–70 years were randomly assigned to consume daily a cake containing 0.75 g of barley β-glucan or a placebo for 30 d. Stool samples were collected before, during and 2 weeks after the intervention for bacterial enumeration. Gastrointestinal side effects were recorded during the treatment period. In older subjects (?50 years old), barley β-glucan induced a strong bifidogenic effect and an increase of bifidobacteria into traceable range in cases of no detectable baseline levels. A concurrent significant increase in bacteroides was also observed in this age group. Ingestion of the experimental food resulted in no undesirable gastrointestinal side effects in older subjects. We concluded that the daily intake of a cake containing barley β-glucan is well-tolerated and demonstrated significant bifidogenic properties in older healthy volunteers consuming their usual diets.     

Deploying LiveWN Grids in the Greek School Network

A determinant factor for the introduction of grid technologies in production domains of scale can be the design of easy, fast and, from an operational point of view, realizable deployment procedures. Remote system management technologies, typically used to monitor and manage IT environments, are designed to offer remote software installation functionality that exhibits the aforementioned characteristics; however, previous work has shown that even valuable systems can fail to perform in heterogeneous, geographically distributed environments, especially if they are maintained by organizations affiliated to the public sector. The deployment of grid technologies throughout the Greek School Network can be achieved by combining OpenRSM, a novel open source solution capable to support usable, configurable, infrastructure management use cases in heterogeneous environments and LiveWN, a grid scavenging solution that integrates live technologies with gLite grids.     

Designing Connection Oriented Networks for Multi-Domain Path Resilience

A challenge in network management and control is the ability to account for multi-domain requirements in the network planning process. Especially in Connection Oriented Networks where multi-domain path finding is a critical issue, networks need to be designed in such a manner as to restrict the possibility of erroneous inter-domain path selection. In this paper we propose per-domain topology design considerations that would leverage accurate disjoint path computations in a multi-domain environment, covering requirements of end-to-end path resiliency. In multi-domain environments state information between domains is heavily aggregated, hiding internal topology details dictated by scalability concerns, but also by restrictive domain administration policies for privacy, and security. Disjoint path finding is strongly affected by the aggregation techniques, since they do not provide information on path overlap. To handle this issue we introduce a metric, the Overlap Factor (OF), that quantifies path overlap in domains. The OF can be passed as an additional parameter of the inter-domain information exchange model to evaluate disjoint end-to-end paths. Alternatively, if domains were appropriately designed, this additional parameter might not be needed in evaluating resilient pairs of inter-domain paths. We based our recommended topology design algorithm on exploiting locally known OF values within the context of Genetic Algorithms. Extensive simulations confirm that domains designed using our proposed algorithm, result into accurate multi-domain disjoint path identification, with a high success ratio compared to networks that are designed without inter-domain considerations.     

Simulation of Terahertz Generation from Lateral Diffusion Currents in Semiconductor Devices

In this paper we model the carrier dynamics and resulting THz emission from lateral diffusion currents within a semiconductor device which has been partially masked by a metallic mask. We present a numerical 1D model and a 1D Monte Carlo simulation which both demonstrate that regardless of the excitation laser spot shape we do not expect to see measurable THz emission in the direction of the optical pump propagation from lateral diffusion currents. Experimentally such devices do produce strong THz emission. We analytically investigate the role of the metal mask and we found that it suppresses the emission of dipoles that are in a region that is less than a wavelength away from the interface. The results from the numerical model are also included in a finite element analysis model of the geometry which predicts THz emission if and only if the metal mask is present.     

Soft tissue differentiation using multiband signatures of high resolution ultrasonic transmission tomography

In this paper, we are interested in soft tissue differentiation by multiband images obtained from the High-Resolution Ultrasonic Transmission Tomography (HUTT) system using a spectral target detection method based on constrained energy minimization (CEM). We have developed a new tissue differentiation method (called "CEM filter bank") consisting of multiple CEM filters specially designed for detecting multiple types of tissues. Statistical inference on the output of the CEM filter bank is used to make a decision based on the maximum statistical significance rather than the magnitude of each CEM filter output. We test and validate this method through three-dimensional interphantom/intraphantom soft tissue classification where target profiles obtained from an arbitrary single slice are used for differentiation over multiple other tomographic slices. The performance of the proposed classifier is assessed using receiver operating characteristic analysis. We also apply our method to classify tiny structures inside a bovine kidney and sheep kidneys. Using the proposed method we can detect physical objects and biological tissues such as styrofoam balls, chicken tissue, calyces, and vessel-duct successfully.     

Fluorescent protein tomography scanner for small animal imaging

Microscopy of fluorescent proteins has enabled unprecedented insights into visualizing gene expression in living systems. Imaging deeper into animals, however, has been limited due to the lack of accurate imaging methods for the visible. We present a novel system designed to perform tomographic imaging of fluorescent proteins through whole animals. The tomographic method employed a multiangle, multiprojection illumination scheme, while detection was achieved using a highly sensitive charge-coupled device camera with appropriate filters. Light propagation was modeled using a modified solution to the diffusion equation to account for the high absorption and high scattering of tissue at the visible wavelengths. We show that the technique can quantitatively detect fluorescence with sub millimeter spatial resolution both in phantoms and in tissues. We conclude that the method could be applied in tomographic imaging of fluorescent proteins for in vivo targeting of different diseases and abnormalities.     

Absorbed dose measurements of a handheld 50 kVP X-ray source in water with thermoluminescence dosemeters

Absorbed dose rate measurements of a 50 kV(p) handheld X-ray probe source in a water phantom are described. The X-ray generator is capable of currents of up to 40 microA, and is designed for cranial brachytherapy and intraoperative applications with applicators. The measurements were performed in a computer-controlled water phantom in which both the source and the detectors are mounted. Two different LiF thermoluminescence dosemeter (TLD) phosphors were employed for the measurements, MTS-N (LiF:Mg,Ti) and MCP-N (LiF:Mg,Cu,P). Two small ionisation chambers (0.02 and 0.0053 cm(3)) were also employed. The TLDs and chambers were positioned in watertight mounts made of water-equivalent plastic. The chambers were calibrated in terms of air-kerma rate, and conventional protocols were used to convert the measurements to absorbed dose rate. The TLDs were calibrated at National Institute of Standards and Technology (NIST) in terms of absorbed dose rate using a (60)Co teletherapy beam and narrow-spectrum X-ray beams. For the latter, absorbed dose was inferred from air-kerma rate using calculated air-kerma-to-dose conversion factors. The reference points of the various detectors were taken as the center of the TLD volumes and the entrance windows of the ionisation chambers. Measurements were made at distances of 3-45 mm from the detector reference point to the source center. In addition, energy dependence of response measurements of the TLDs used was made using NIST reference narrow spectrum X-ray beams. Measurement results showed reasonable agreement in absorbed dose rate determined from the energy dependence corrected TLD readings and from the ionisation chambers. Volume averaging effects of the TLDs at very close distances to the source were also evident.     

Quantitative Evaluation of Thermal Inactivation Kinetics of Free-Floating Versus Surface-Attached Listeria innocua Cells

Surface pasteurization is one of the decontamination treatments that can contribute to better preservation of meat products retaining most of their quality characteristics relatively intact if compared with the raw products. The current research compares the kinetics of free-floating and surface attached Listeria innocua cells by using integrated microbial and heat transfer modelling approaches. Surface pasteurization treatments are applied on a (abiotic) Teflon® model system in a novel steam surface decontamination rig. The experimental set-up prevented following four technological aspects to occur, (1) cold purge migration to the surface during the heating process, (2) inactivation kinetics of a cocktail of microbes, (3) protective effect of food components, and (4) physical distribution of bacteria throughout the depth of the product skin. Microbial load predictions are performed based on the inactivation parameters obtained during free-floating cell experiments. These predictions, when compared with the microbial data of the surface treatments, prove that the surface attached cells were much more heat resistant, despite the experimental set-up preventing the aforementioned (technological) events to occur. Indeed, surface attached cells can have different physiological/phenotypical/genetical characteristics, such as cell aggregations, colony formations, presence of flagella. In a final step, three techniques are implemented to evaluate mathematically the kinetics of the surface attached cells. Overall, this research’s significance is lying in the quantitative assessment of microbial heat resistance. The technological reasons underlying the increased microbial heat resistance on biotic and abiotic surfaces should be reevaluated, taking into account possible physiological/phenotypical/genetical characteristics.     

Multilayer thermal object identification in frequency domain using IR thermography and vector fitting

This paper deals with the identification of the thermal parameters of multilayer objects using the concept of thermal impedance. In order to perform such identification, temperature evolution in time is obtained by an infrared camera after power excitation is applied in the investigated structure. Infrared thermography offers the advantage of being a noncontact temperature detection and measurement method. In many practical cases, it is impossible to use contact temperature measurements. Typically, the power in the form of a step function is applied. In order to calculate the thermal impedance of an object, temperature and power are converted into the frequency domain using the Laplace transform for s = jω. Then, the poles of the thermal impedance are identified using vector fitting, which allows calculating the thermal impedance as a sum of partial fractions. This corresponds directly to the Foster network of a thermal object. In addition, the vector fitting method offers much better convergence in comparison with other methods using the polynomial rational approximation of thermal impedance. A considerable improvement of the numerical Laplace transform in high frequency range is proposed. In this approach, the variable s = jω is replaced by , and then, the integration result is corrected by the Taylor series. It leads to a kind of filtering of the temperature signal.