Analysis of nonvolatile material in solvent hexane

The amount and composition of the nonvolatile residue in solvent hexane are important quality criteria. These residue characteristics are particularly significant in the hexane extraction of foods because of the possibility of contaminating edible products. A laboratory evaluation of the residue from a typical hexane was made to find if there was any trace of multi-ring aromatics which might be potential carcinogens. Samples of hexane directly from a refinery and after storage and transportation to two solvent extraction plants were analyzed. All residues were separated by paper chromatography and analyzed by ultraviolet spectrophotometry. In no case, were they found to contain polynuclear aromatic carcinogenic materials. The test method is sensitive to less than 0.01 ppm. In order to verify the accuracy of the test, an analysis was made for the quantitative recovery of a known carcinogen. For this purpose, 0.01 ppm of 3,4 benzpyrene was added to the hexane as an internal standard and the analysis conducted as before. In these tests, the benzpyrene was recovered quantitatively.     

Control policies for an industrial acetylene hydrogenation reactor

This paper addresses the problem of finding optimal operational policies for an acetylene reactor for day to day operation. A lumped parameter model based on four main reactions is developed and used to examine the effects of the reactor manipulated variables on key reaction parameters. An optimal and a sub-optimal operational policy which minimize the ethylene loss over time are formulated and the solution techniques are presented. The results indicate that the reactor model is in good agreement with industrial plant data. The performance of the optimal control policy is very similar to the performance of the sub-optimal control policy. However, the sub-optimal formulation, while retaining the dominant features of the optimal response, reduces the computational requirements. Finally, some issues concerning the real-time implementation of an advanced acetylene reactor control scheme are presented. These include the estimation of the optimum regeneration cycle, a recursive model update algorithm, the process optimizer and their overall coordination. A preliminary analysis of the benefits associated with the advanced control scheme suggests a considerable reduction in the yearly ethylene loss.     

The Use of Context-Aware Policies and Ontologies to Facilitate Business-Aware Network Management

The purpose of autonomic networking is to manage the business and technical complexity of networked components and systems. However, existing network management data has no link to business concepts. This makes it very difficult to ensure that services offered by the network are meeting business objectives. This paper describes a novel context-aware policy model that uses a combination of modeled and ontological data to determine the current context, which policies are applicable to that context, and what services and resources should be offered to which users and applications.

SellTrend: Inter-Attribute Visual Analysis of Temporal Transaction Data

We present a case study of our experience designing SellTrend, a visualization system for analyzing airline travel purchase requests. The relevant transaction data can be characterized as multi-variate temporal and categorical event sequences, and the chief problem addressed is how to help company analysts identify complex combinations of transaction attributes that contribute to failed purchase requests. SellTrend combines a diverse set of techniques ranging from time series visualization to faceted browsing and historical trend analysis in order to help analysts make sense of the data. We believe that the combination of views and interaction capabilities in SellTrend provides an innovative approach to this problem and to other similar types of multivariate, temporally driven transaction data analysis. Initial feedback from company analysts confirms the utility and benefits of the system.     

Metal/dielectric transmission interference filters with low reflectance. 2. Experimental results

The successful fabrication of metal/dielectric multilayer filters requires not only accurate control of the individual layer thicknesses, but also a good knowledge of the optical constants of the materials used in the filters. In the case of metal films, it is also essential to know whether any transition layers are formed at the interfaces and, if so, how their thicknesses and optical constants depend on the deposition conditions. An automatic, real-time process control, magnetron sputtering deposition system was modified to permit the manufacture of metal/dielectric filters using optical monitoring techniques. To illustrate the performance of this system, two bandpass filters, a short-wavelength pass filter, and a neutral density filter were produced, all having a low reflectance for light incident on one side. The metal layers used in these filters consisted of either Ni or Ag. TheAg films could be protected from the O(2) plasma using thin Ni or Si films. Good agreement was obtained between the calculated and measured spectral transmittance and reflectance curves.     

A dual mesh scheme for finite element based reconstruction algorithms

The finite element (FE) method has found several applications in emerging imaging modalities, especially microwave imaging which has been shown to be potentially useful in a number of areas including thermal estimation. In monitoring temperature distributions, the biological phenomena of temperature variations of tissue dielectric properties is exploited. By imaging these properties and their changes during such therapies as hyperthermia, temperature distributions can be deduced using difference imaging techniques. The authors focus on a microwave imaging problem where the hybrid element (HE) method is used in conjunction with a dual mesh scheme in an effort to image complex wavenumbers, k(2). The dual mesh scheme is introduced to improve the reconstructed images of tissue properties and is ideally suited for systems using FE methods as their computational base. Since the electric fields typically vary rapidly over a given body when irradiated by high-frequency electromagnetic sources, a dense mesh is needed for these fields to be accurately represented. Conversely, k(2) may be fairly constant over subregions of the body which would allow for a less dense sampling of this parameter in those regions. In the dual mesh system employed, the first mesh, which is uniformly dense, is used for calculating the electric fields over the body whereas the second mesh, which is nonuniform and less dense, is used for representing the k(2) distribution within the region of interest. The authors examine the 2-D TM polarization case for a pair of dielectric distributions on both a large and small problem to demonstrate the flexibility of the dual mesh method along with some of the difficulties associated with larger imaging problems. Results demonstrate the capabilities of the dual mesh concept in comparison to a single mesh approach for a variety of test cases, suggesting that the dual mesh method is critical for FE based image reconstruction where rapidly varying physical quantities are used to recover smoother property profiles, as can occur in microwave imaging of biological bodies.     

Brain stem integration of vocalization: role of the nucleus retroambigualis

1. The descending pathways that mediate the periaqueductal gray (PAG)-evoked coordination of respiratory, laryngeal, and orofacial activity for vocalization have yet to be delineated. Two hypotheses have been offered. One theory is that this activity is mediated by a diffuse descending projection to parvocellular reticular interneurons, adjacent to the relevant laryngeal and orofacial motoneuronal pools. The second hypothesis is that the motor activity for vocalization is integrated via a projection from the PAG to a caudal medullary column of neurons, the nucleus retroambigualis (NRA). These hypotheses were tested with the use of a series of medullary transections combined with PAG stimulation. Transections that eliminated, in a series of caudal-to-rostral steps, the NRA, also eliminated the PAG-evoked cricothyroid and most of the thyroarytenoid laryngeal motor activity. These results indicate that the final common pathway for much of the laryngeal activity in PAG-evoked vocalization includes un initial synapse in the caudal medulla, presumably in the NRA. 2. The electromyographic changes evoked by microinjection of D,L-homocysteic acid (DLH) in the NRA of the unanesthetized, precollicular decerebrate cat were analyzed in order to delineate the NRA contribution to the coordinated respiratory, laryngeal, and oral muscle changes in vocalization. A total of 415 DLH injection sites were located at or caudal to the level of the obex. Vocalization was evoked at 46 of these sites, which were all confined to a restricted region of the ventrolateral medulla 1-3 mm caudal to the obex. This region corresponded to the rostral half of the NRA and the immediately adjacent medullary tegmentum. 3. In all experiments evidence was obtained that variable muscle activation, rather than functional and integrated muscle patterns, was represented within the NRA. Vocalization evoked by DLH microinjection in the NRA was usually associated with excitation of the cricothyroid, thyroarytenoid, external oblique, internal oblique, internal intercostal, and diaphragm muscles that occurred in a different manner from site to site. That is, injection at sites separated by 0.3-0.5 mm evoked quite different responses. 4. NRA-evoked vocalization was compared with PAG-evoked vocalization using small injections (1.5-4.5 nl) into each region. As well, larger microinjections (15-120 nl) into NRA were made for comparison with previous results from the PAG using similar doses. Within the PAG, stereotyped and relatively "fixed" patterns of muscle activity are represented, whereas within the NRA there was no representation of specific muscle patterns, but rather a partial topographic separation of "premotor neurons" regulating different muscles. Correspondingly, stereotyped vocalizations were never evoked from the NRA. Further, most NRA-evoked vocalizations were unusual in quality and would not be identified generally as feline. 5. Evidence was obtained for a separation of pathways from the PAG regulating sound production and orofacial modulation of that sound. In contrast to the results from the PAG, excitation of NRA neurons rarely evoked activity in the oral muscles (genioglossus or anterior belly of digastric) or orofacial modulation of sound production. 6. Our finding suggests that the NRA serves as an important substrate for the generation of respiratory pressure and larynges adduction, which are two essential aspects of not only vocalization but also several behaviors involving Valsava maneuvers such as coughing, vomiting, and defecation.     

Developmental aspects of dendritic cells in vitro and in vivo

Our knowledge in immunology has been dramatically increased by several excellent investigations elucidating the role of the Fas (Apo-1/CD95) receptor/ligand (FasL) system in complex immunological processes such as the acquisition of self tolerance in T cells, progression of autoimmunity, clonal deletion of activated T cells, B-cell regulation and the establishment of "immune privileged" sites such as testis or retina. In addition to these regulatory immunological activities, Fas/FasL interaction was also shown to participate in active defense mechanisms of the host against infected or transformed cells thereby inducing apoptosis in target cells. However, the same mechanism seems also to be part of an escape strategy utilized by tumor cells in various neoplastic malignancies of both hematopoetic as also non-hematopoetic origin. We ourselves were able to demonstrate that neoplastic plasma cell lines, as well as native malignant myeloma cells constitutively express FasL mRNA and protein. The FasL molecule is functionally active and able to induce programmed cell death in Fas sensitive target T cells in vitro. These target T cells were protected from programmed cell death by preincubation of T cells with a Fas-blocking monoclonal antibody (mAb) or of myeloma cells with a FasL-neutralizing mAb. respectively. Furthermore, overexpression of the caspase inhibitor, cowpoxvirus protein CrmA, also protected target T cells from being killed by myeloma cells, identifying Fas/FasL mediated signaling as the effector pathway utilized by malignant plasma cells. Our observations strongly suggest the engagement of Fas/FasL interaction in the escape strategy of this malignancy. The molecular basis of this evasive mechanism differs in essential respects from those described in melanoma, lung cancer, hepatocellular carcinoma, or astrocytoma, since downregulation of Fas or instrinsic insensitivity towards Fas-mediated signaling were not prerequisites for the occurrence of this phenomenon in Fas-sensitive multiple myeloma cell lines. However, myeloma cell lines resisted cocultivation with FasL-expressing target T cells in vitro. The aim of this review is to discuss the role of Fas/FasL interaction in the establishment of malignant disease, in the light of our findings on myeloma cells and also by drawing upon similar observations of other investigators on different kinds of tumor cells and cell lines and further to consider its possible relevance in formulating novel approaches to cancer therapy.