A Knowledge Based Semantics of Messages

We investigate the semantics of messages, and argue that the meaning ofa message is naturally and usefully given in terms of how it affects theknowledge of the agents involved in the communication. We note thatthis semantics depends on the protocol used by the agents, and thus not only the message itself, but also the protocol appears as a parameter in the meaning. Understanding this dependence allows us to give formal explanations of a wide variety of notions including language dependence, implicature, and the amount of information in a message.     

Incomplete hypospadiac urethral duplication with posterior urethral valves

Urethral duplication (UD) is an uncommon malformation. Obstruction rarely occurs in hypospadiac UD. We describe two children with incomplete hypospadiac UD in association with posterior urethral valves, a combination not previously recognised. The embryonic significance of this anomaly is discussed. Keywords Urethral duplication. Hypospadias. Posterior urethral valve. Megalourethra     

Photoinduced anisotropy in a family of amorphous azobenzene polyesters for optical storage

We investigate parameters associated with optical data storage in a variety of amorphous side-chain azobenzene-containing polyesters denoted as E1aX. The polyesters possess a common cyano-substituted azobenzene chromophore as a side chain, but differ in their main-chain polyester composition. Seventeen different polymers from the E1aX family divided into four classes, depending on the type of the main-chain substituent (one-, two-, and three-ring aromatic or alicyclic) have been thoroughly investigated. Various parameters characterizing the photoinduced birefringence in these materials, such as the response time, thermal and light stability, and long-term stability under ambient light at room temperature have been measured. Each of these parameters is quantitatively represented and therefore it is possible to make a clear comparison between the properties of the polymers. The results indicate that the long-term stability at ambient temperature is closely related to the thermal stability of the photoinduced birefringence. A strong correlation has also been found between the response time and the stability of the induced anisotropy toward illumination with unpolarized white light. One of the classes of E1aX polymers characterized by two-ring aromatic substituent in the main chain is a good candidate for optical data storage media. A recording energy of approximately 2 J/cm2 is sufficient to induce high refractive-index modulations of deltan = 0.13 in these materials, which is retained even at elevated temperatures (>130 degrees C). Long-term stability of greater than one year for the induced anisotropy has also been achieved.     

Electromagnetic spectroscopy of normal breast tissue specimens obtained from reduction surgeries: comparison of optical and microwave properties

Techniques utilizing electromagnetic energy at microwave and optical frequencies have been shown to be promising for breast cancer detection and diagnosis. Since different biophysical mechanisms are exploited at these frequencies to discriminate between healthy and diseased tissue, combining these two modalities may result in a more powerful approach for breast cancer detection and diagnosis. Toward this end, we performed microwave dielectric spectroscopy and optical diffuse reflectance spectroscopy measurements at the same sites on freshly excised normal breast tissues obtained from reduction surgeries at the University of Wisconsin Hospital, using microwave and optical probes with very similar sensing volumes. We found that the microwave dielectric constant and effective conductivity are correlated with tissue composition across the entire measurement frequency range ($vert rvert sim 0.5hbox{--}0.6, p ≪ 0.01$) and that the optical absorption coefficient at 460 nm and optical scattering coefficient are correlated with tissue composition ($vert rvert sim 0.4hbox{--}0.6, p≪ 0.02$). Finally, we found that the optical absorption coefficient at 460 nm is correlated with the microwave dielectric constant and effective conductivity ($r = hbox{--}0.55, p≪ 0.01$ ). Our results suggest that combining optical and microwave modalities for analyzing breast tissue samples may serve as a crosscheck and provide complementary information about tissue composition.      

Minimizing data and synchronization costs in one-way communication

Minimizing communication and synchronization costs is crucial to the realization of the performance potential of parallel computers. This paper presents a general technique which uses a global data-flow framework to optimize communication and synchronization in the context of the one-way communication model. In contrast to the conventional send/receive message-passing communication model, one-way communication is a new paradigm that decouples message transmission and synchronization. In parallel machines with appropriate low-level support, this may open up new opportunities not only to further optimize communication, but also to reduce the synchronization overhead. We present optimization techniques using our framework for eliminating redundant data communication and synchronization operations. Our approach works with the most general data alignments and distributions in languages like High Performance Fortran (HPF) and uses a combination of the traditional data-flow analysis and polyhedral algebra. Empirical results for several scientific benchmarks on a Cray T3E multiprocessor machine demonstrate that our approach is successful in reducing the number of data (communication) and synchronization messages, thereby reducing the overall execution times     

Erosion mechanisms of thermally sprayed coatings with multiple phases

Thermally sprayed coatings are frequently subjected to impacts by small solid particles which induce surface erosion. To identify the physical mechanisms associated with such a material removal process, experimental tests as well as detailed computational analyses of porous coatings containing multiple phases are performed. In the experiments, a gas jet erosion test is conducted to measure material loss of coatings with different mixtures of brittle and ductile phases. The results show higher erosion resistances with small volume fractions of metal phase added to predominantly brittle coatings. Following this outcome, the study is directed toward elucidating the physical mechanisms behind the increased erosion resistance. Here, solid particle impacts are simulated with dynamic finite element analyses where material removals and coating's energy absorption behaviors are closely monitored. Furthermore, parametric study is carried out to quantify effects of cracking resistances and plastic dissipation on the erosion rate. The results reveal synergistic effects of fracture energy and plastic deformation. The combined mechanisms allow greater energy absorptions and enhanced erosion resistance in coatings with mixture of ductile phase. These assessments should offer insights into tailoring coatings with optimized composition of ductile phase to increase their performances. The results are also valuable in understanding foreign object damage (FOD) of coatings.