Scanning electron microscopical studies of developing gustatory papillae in humans

Yeast biomass (Saccharomyces sp.) produced in local breweries as a by-product was utilized in this study. Percent proximate composition, amino acid composition, and protein nutritive value were determined for the yeast cell biomass (YC), a sodium perchlorate extracted and isoelectrically precipitated protein concentrate (P-PC), and a sodium trimetaphosphate treated extract followed by isoelectrical precipitation (TMP-PC). Protein concentrates averaged 75% protein as compared to 48.5% in the yeast biomass. Precipitation of the protein in the presence of either sodium perchlorate or sodium trimetaphosphate was reduced to 71% and 51% of the cell RNA content, respectively. Protein nutritive value was 70% of casein when measured by the protein efficiency ratio (PER), and over 90% of casein when net protein utilization (NPUa) was the criteria of evaluation.     

Managing occupational HIV exposures: a Canadian study

The findings reported in this paper are part of a larger study that explored how nurses cope with the risk of acquiring HIV infection while caring for persons with AIDS (PWAs). The data were collected through in-depth interviews with 13 nurses who cared for PWAs in a large Western Canadian hospital. Seven of these nurses perceived that they had been exposed to HIV-infected blood or body fluids. This paper describes how these seven nurses coped with actual exposures to HIV-infected blood or body fluids. Data were analyzed using the methodology of grounded theory. Nurses' coping efforts after exposure were grouped into four categories: minimizing the effect of exposures, reducing a sense of vulnerability, selective disclosure to others, and assigning meaning. Nurses minimized the physical effects of exposure through measures such as 'bleeding' the needlestick injury and immersing the affected area in bleach solution. Nurses reduced their sense of vulnerability by assessing the possibility of harm, avoiding situations that aroused fear, and confronting the decision for HIV testing. Nurses limited their disclosures to co-workers to avoid rejection and to preserve professional self-esteem. Disclousre to significant others was influenced primarily by the support nurses perceived they would receive. Finally, nurses attempted to assign meaning to the exposure by determining why the event occurred and by evaluating the implications it has had on their lives. The article concludes with implications for nursing practice.     

Biomass-integrated gasification fuel cell systems – Part 1: Definition of systems and technical analysis

The combination of biomass gasification with fuel cells is commonly referred to as Biomass-Integrated gasification fuel cell systems (B-IGFC). In this two-part system analysis, we investigate seven B-IGFC systems and four solid oxide fuel cell (SOFC) designs with a system power output of around 1 MW_el. In this part, we define the B-IGFC systems and asses their technical feasibility using a finite volume based SOFC model and ASPEN PLUS™ models for the simulation of the gas processing.     

Fiber-Reinforced Ceramic-Matrix Composites with a Polysiloxane/Boron-Derived Matrix

A ceramic matrix for carbon-fiber-reinforced ceramic-matrix composites (CMCs) has been developed from polysiloxane/boron mixtures. Complex geometries can be realized by using standard technologies of fiber-reinforced polymer composites. On pyrolysis, the polymer-filler mixture is converted to a ceramic matrix, consisting of silicon carbide, boron carbide, boron nitride, and a silicon oxycarbide (SiOC) glass, without reacting with the carbon fiber. Because of the large volume increase of the boron filler on nitridation (142 vol%), no multiple reinfiltration of the structure is necessary to achieve a dense matrix. Tensile strength and interlaminar shear strength exhibit maxima at a pyrolysis temperature of 1300°C, where extensive fiber pullout is observed. Thermodynamic calculations have been used to evaluate the theoretical qualitative and quantitative phase compositions at equilibrium. Thermoanalytical (thermogravimetry-mass spectroscopy) and structural analysis (X-ray diffractometry) have shown a satisfying coherence with respect to the condensed phases, whereas deviations have been noted with respect to the composition of the gas phase.     

Securing the data path of next-generation router systems

As the technology used to implement computer network infrastructure advances, networking resources are becoming more vulnerable to attack. Recent router designs are based on general-purpose programmable processors, which increase their potential vulnerability. To address this issue, a Secure Packet Processing platform has been developed that can flexibly protect emerging router systems. Both instruction-level operation of embedded processors and I/O operations of router ports are monitored to detect anomalous behavior. If such behavior is detected, a recovery system is invoked to restore the system into an operational state. Experimental results show that processor-based attacks can generally be determined by a processing monitor within a single instruction. I/O anomalies, including unexpected packet broadcast or delay, can be detected by an I/O monitor with limited overhead. Overall, the system overhead for secure monitoring is limited to a fraction of the overall system space, memory, and power budget.     

Automated determination of the center of rotation in tomography data

Tomographic reconstruction requires precise knowledge of the position of the center of rotation in the sinogram data; otherwise, artifacts are introduced into the reconstruction. In parallel-beam microtomography, where resolution in the 1 microm range is reached, the center of rotation is often only known with insufficient accuracy. We present three image metrics for the scoring of tomographic reconstructions and an iterative procedure for the determination of the position of the optimum center of rotation. The metrics are applied to model systems as well as to microtomography data from a synchrotron radiation source. The center of rotation is determined using the image metrics and compared with the results obtained by the center-of-mass method and by image registration. It is found that the image metrics make it possible to determine the axis position reliably at well below the resolution of one detector bin in an automated procedure.     

Methods for determining regularization for atmospheric retrieval problems

The atmosphere of Earth has already been investigated by several spaceborne instruments, and several further instruments will be launched, e.g., NASA's Earth Observing System Aura platform and the European Space Agency's Environmental Satellite. To stabilize the results in atmospheric retrievals, constraints are used in the iteration process. Therefore hard constraints (discretization of the retrieval grid) and soft constraints (regularization operators) are included in the retrieval. Tikhonov regularization is often used as a soft constraint. In this study, different types of Tikhonov operator were compared, and several new methods were developed to determine the optimal strength of the constraint operationally. The resulting regularization parameters were applied successfully to an ozone retrieval from simulated nadir sounding spectra like those expected to be measured by the Tropospheric Emission Spectrometer, which is part of the Aura platform. Retrievals were characterized by means of estimated error, averaging kernel, vertical resolution, and degrees of freedom.