Evaluation of an IUL Flash & Go Automated Colony Counter

An IUL Flash & Go automated colony counter was used to enumerate E. coli (ATCC 700728) colonies and its performance was compared with manual counting on spiral plates. A total of 85 plates were analyzed. Linear regression analysis and the log differences between the manual and automated counts were determined. The results were analyzed to evaluate the reliability and accuracy of the colony counter.  A correlation coefficient of 0.969, a slope of 0.932 and intercept of 0.25 all indicate a strong, linear relationship. The mean log value difference between the manual and Flash & Go count methods was -0.035. Of the 85 plates counted, 95% of the plates were within 0.15 log10 difference between the manual and Flash & Go automated counts. These results demonstrate that the Flash & Go automated colony counter is an effective, accurate and time saving alternative to the standard method of manual counting.      

Amino­guanidinium hydrogen succinate

The title compound, CH7N4 +·C4H5O4 −, is a molecular salt containing discrete amino­guanidinium and succinate ions. The amino­guanidinium cation is nearly planar, with a maximum deviation of 0.035 (1) Å. The dihedral angle between the amino­guanidinium cation and the succinate anion is 3.35 (6)°. The crystal packing exhibits inter­molecular N—H⋯O and O—H⋯·O hydrogen bonds

SCHEMA Recombination of a Fungal Cellulase Uncovers a Single Mutation That Contributes Markedly to Stability

A quantitative linear model accurately (R^2 = 0.88) describes the thermostabilities of 54 characterized members of a family of fungal cellobiohydrolase class II (CBH II) cellulase chimeras made by SCHEMA recombination of three fungal enzymes, demonstrating that the contributions of SCHEMA sequence blocks to stability are predominantly additive. Thirty-one of 31 predicted thermostable CBH II chimeras have thermal inactivation temperatures higher than the most thermostable parent CBH II, from Humicola insolens, and the model predicts that hundreds more CBH II chimeras share this superior thermostability. Eight of eight thermostable chimeras assayed hydrolyze the solid cellulosic substrate Avicel at temperatures at least 5 °C above the most stable parent, and seven of these showed superior activity in 16-h Avicel hydrolysis assays. The sequence-stability model identified a single block of sequence that adds 8.5 °C to chimera thermostability. Mutating individual residues in this block identified the C313S substitution as responsible for the entire thermostabilizing effect. Introducing this mutation into the two recombination parent CBH IIs not featuring it (Hypocrea jecorina and H. insolens) decreased inactivation, increased maximum Avicel hydrolysis temperature, and improved long time hydrolysis performance. This mutation also stabilized and improved Avicel hydrolysis by Phanerochaete chrysosporium CBH II, which is only 55–56% identical to recombination parent CBH IIs. Furthermore, the C313S mutation increased total H. jecorina CBH II activity secreted by the Saccharomyces cerevisiae expression host more than 10-fold. Our results show that SCHEMA structure-guided recombination enables quantitative prediction of cellulase chimera thermostability and efficient identification of stabilizing mutations

Piperazinediium dioxamate

The title compound, C4H12N2 2+·2C2H2NO3 −, contains a network of doubly protanated piperazinium cations (lying about centres of inversion) and dioxamate anions. The piperazinium dication adopts a typical chair conformation. The crystal structure is stabilized by cation–to–anion N—H⋯O and anion–to–anion N—H⋯O hydrogen bonds

Chimeric Anti-Staphylococcal Enterotoxin B Antibodies and Lovastatin Act Synergistically to Provide In Vivo Protection against Lethal Doses of SEB

Staphylococcal enterotoxin B (SEB) is one of a family of toxins secreted by Staphylococcus aureus that act as superantigens, activating a large fraction of the T-cell population and inducing production of high levels of inflammatory cytokines that can cause toxic shock syndrome (TSS) and death. Extracellular engagement of the TCR of T-cells and class II MHC of antigen presenting cells by SEB triggers the activation of many intracellular signaling processes. We engineered chimeric antibodies to block the extracellular engagement of cellular receptors by SEB and used a statin to inhibit intracellular signaling. Chimeric human-mouse antibodies directed against different neutralizing epitopes of SEB synergistically inhibited its activation of human T-cells in vitro. In the in vivo model of lethal toxic shock syndrome (TSS) in HLA-DR3 transgenic mice, two of these antibodies conferred significant partial protection when administered individually, but offered complete protection in a synergistic manner when given together. Similarly, in vivo, lovastatin alone conferred only partial protection from TSS similar to single anti-SEB antibodies. However, used in combination with one chimeric neutralizing anti-SEB antibody, lovastatin provided complete protection against lethal TSS in HLA-DR3 transgenic mice. These experiments demonstrate that in vivo protection against lethal doses of SEB can be achieved by a statin of proven clinical safety and chimeric human-mouse antibodies, agents now widely used and known to be of low immunogenicity in human hosts

cl: A Language for Formally Defining Web Services Interactions

Web services have emerged recently as a distributed computing paradigm of choice for loosely-coupled computing. Current web services standards such as SOAP, and WSDL provide rudimentary mechanisms for defining interaction amongst services that may be located in di#erent organizations. While WSDL provides the definitions for the entry-points of a service, in many cases, the interactions between services has more structure than can be described by just the definition of entry points. In particular, the sequence of interactions often is an important component of interactions between services. In current web services standards, the notion of sequencing is handled by the workflow definitions provided by proposals such as BPEL4WS. Although workflow definitions are clearly powerful enough to express all possible sequences of message exchanges between services, our approach is di#erent. Our contention is that sharing workflow definitions across services will enable inter-operability, but leads to tighter coupling amongst the services

A Note on Polynomials with Non-negative Integral Coefficients

To identify polynomials one usually requires the value of the polynomial at d + 1 points where d is the degree of the polynomial. In this note we show that every polynomial with non-negative integral coefficients can be identified by knowing its value at two cleverly chosen points irrespective of the degree and the number of terms in the polynomial. 1 Introduction The problem of learning a function from a finite number of examples of its input-output behavior has been studied in the literature [1]. The applications of the above problem lie in the areas such as program testing [4, 2, 6], and program synthesis [7]. Although inferring arbitrary functions from a finite number of examples is clearly impossible, we are interested in identifying reasonable classes of functions that can be inferred from a finite number examples. Furthermore, we are also interested in reducing the number of examples of input-output behavior that have to be examined in order to identify functions uniquely. In th..

Optimization and Relaxation in Logic Languages

Acknowledgements I wish to thank: 1. my advisor, Bharat Jayaraman, to whom this dissertation owes its existence in an uncountable number of ways, 2. Surya Mantha of Xerox Corporation, for input at various crucial stages, 3. Xerox Corporation, for generously providing funds that supported most of this work, 4. the rest of my committee, namely, Prof. Alan L. Selman and Prof. Kenneth W. Regan, for their interest in my welfare, 5. the secretaries in the department of computer science, for, among other things, shielding me from administrivial vagaries of the University, 6. my friends, for believing in, supporting, and encouraging me through thick andthin. I shall refrain from enumerating names here for fear of making the list longer than the rest of my dissertation