Extracellular and bacterial factors influencing staphylococcal phagocytosis and killing by human polymorphonuclear leukocytes

Extracellular and bacterial factors that influence the phagocytosis and killing of staphylococci by human polymorphonuclear leukocytes have been studied. Staphylococcus epidermidis strains were, in general, more rapidly phagocytized than were S. aureus strains. However, two strains of S. epidermidis had a very slow rate of ingestion. Although the rate of phagocytosis of S. aureus Wood 46 was greater than that of S. aureus 502A, the Wood 46 strain was more difficult to kill. Serum was essential for phagocytosis of both S. aureus and S. epidermidis. The opsonic titer of pooled serum was similar for S. aureus and S. epidermidis. In normal pooled serum, heat-labile factors were more important for effective phagocytosis than they were in immune serum. Although a saturation point for ingestion was reached, the percentage of ingested bacteria that remained alive within the leukocyte remained relatively fixed. Heat-killed and live staphylococci were igested in a similar fashion. The rate of phagocytosis was greatly reduced at 41 degrees C.     

Metal ion/buffer interactions. Stability of binary and ternary complexes containing 2-[bis(2-hydroxyethyl)amino]-2(hydroxymethyl)-1,3-propanediol (Bistris) and adenosine 5'-triphosphate (ATP)

The acidity constant of protonated 2-[bis(2-hydroxyethyl)amino]-2(hydroxymethyl)-1,3-propanediol (Bistris) has been measured. The influence of hydroxo groups on the basicity of Bistris and related bases is discussed. The interaction of Bistris with the metal ions (M2+) Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, and Pb2+ was studied by potentiometry and spectrophotometry in aqueous solution (I = 1.0 M, KNO3; 25 degrees C) and the stability constants of the M(Bistris)2+ complexes were determined. Unexpectedly Ca(Bistris)2+ is the most stable among the alkaline earth ion complexes (log KCaCa(Bistris) = 2.25; the corresponding values for the Mg2+, Sr2+ and Ba2+ complexes are 0.34, 1.44 and 0.85, respectively). The ions of the 3d series follow the Irving-Williams sequence: log KMnMn(Bistris) = 0.70, for Cu2+, 5.27 and Zn2+ 2.38. Ternary complexes containing ATP4- as a second ligand were also investigated: the values for delta log KM (= log KM(ATP)M(ATP)(Bistris) -log KMM(Bistris) are in general negative (e.g. delta log KCa = -0.40 or delta log KCu = -1.65), thus indicating that the interaction of Bistris with M(ATP)2- is somewhat less pronounced tan with M2+. However, even in mixed-ligand systems, complex formation may still be considerable, hence great reservations should be exercised in employing Bistris as a buffer in systems containing metal ions. Moreover, in several cases delta log KM is relatively high [for Mg2+-ATP4- -Bistris even positive], indicating some cooperativity between the coordinated ligands, possibly hydrogen-bond formation. Distributions of the complexes in dependence on pH are given, and the structures of the binary M(Bistris)2+ and the ternary M(ATP) (Bistris)2- complexes are discussed. The participation of Bistris hydroxo groups in complex formation is evident.     

The use of tape recording to simulate a group atmosphere.

"The present study explores the possibility that tape recordings can be used to communicate to a test subject the experience that he is a participating member of a social group… . In this study a group frame of reference was created for the autokinetic effect solely by auditory stimulation. The reports of all 'other' Ss were recorded and communicated to the critical S over headphones." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Task difficulty and conformity pressures.

This study using 60 Ss showed that conformity pressures are more easily exerted when the person is poorly informed with respect to questions of general information. When certain of the correct answers, the person is more easily able to resist pressures, but when uncertain he is more prone to use supplemental external information as the basis for making responses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Using Component-Based Development and Web Technologies to Support a Distributed Data Management System

Over recent years, Internet-able applications have been used to support domains where distributed functionality is essential. This flexibility is also pertinent in situations where data is collected and derived to support a distributed set of stakeholders. There are major problems in this distributed data management scenario. One problem is the change that occurs in such domains. Both the schema of the data and the individual needs of the stakeholders evolve over time. Any architecture to support this distributed data management domain must be designed to support these specific changes. One such approach to this architecture is the use of plug-able web-based components. As new computational needs arise, new components can be plugged into the architecture. Another aspect of this solution architecture is toward a run-time evolvable process to support the change of the data schemas. At the MITRE Corporation, this architecture has been designed, deployed and tested to support the internal need for a composite data repository. This paper presents the motivation and architecture of this distributed data management system that supports the Center for Advanced Aviation System Development (CAASD). This component-based run-time configurable architecture is implemented using web-based technologies, such as the Extensible Markup Language (XML), Java Servlets, and a relational database management system (RDBMS).     

Probabilistic Tracking with Exemplars in a Metric Space

A new, exemplar-based, probabilistic paradigm for visual tracking is presented. Probabilistic mechanisms are attractive because they handle fusion of information, especially temporal fusion, in a principled manner. Exemplars are selected representatives of raw training data, used here to represent probabilistic mixture distributions of object configurations. Their use avoids tedious hand-construction of object models, and problems with changes of topology.Using exemplars in place of a parameterized model poses several challenges, addressed here with what we call the Metric Mixture (M²) approach, which has a number of attractions. Principally, it provides alternatives to standard learning algorithms by allowing the use of metrics that are not embedded in a vector space. Secondly, it uses a noise model that is learned from training data. Lastly, it eliminates any need for an assumption of probabilistic pixelwise independence.Experiments demonstrate the effectiveness of the M² model in two domains: tracking walking people using chamfer distances on binary edge images, and tracking mouth movements by means of a shuffle distance.     

Removing aperture-induced artifacts from Fourier transform infrared intensity values

Two Fourier transform infrared intensity artifacts have been observed at moderately high (0.1 cm(-1)) spectral resolution: Light reflected off the aperture was double modulated by the interferometer, producing a 2f alias, and the warm (approximately 310 K) annulus of the aperture seen by a cooled detector resulted in distorted line shapes and anomalous intensities in the fingerprint region. Although the second artifact has been alluded to previously, we report corrections to remove both of these anomalies and to demonstrate the efficacy of these corrections. Prior to correction, integrated-band intensities were found to be in error by up to 12%.     

Bio-Inspired Actuation and Sensing

The superb ability of animals to negotiate rough terrain has caused engineers to focus on mechanical properties of muscle and other unique features in order to design improved robots for exploration. This paper reviews recent work in artificial muscle actuators, as well as a new sensor based on a robotic model of the muscle spindle cell. The actuator contains a pneumatic force generator in parallel with a non-linear damping element and in series with a non-linear elastic tendon. Work loop experiments were performed to characterize this actuator under conditions similar to real locomotion at different speeds. The robotic muscle spindle is an 8 × 1 cm device which simulates the response of the physiological muscle spindle to stretch. Its non-linear properties are thought to contribute to stable accurate control over a wide range of motion.     

Redefinable crossassembler for horizontally microprogrammable processors

A two-phase meta-assembler is described. The software was designed to assemble microprograms for several different microprogrammable processor architec