Towards a Theory of Regular MSC Languages

Message Sequence Charts (MSCs) are an attractive visual formalism widely used to capture system requirements during the earlydesign stages in domains such as telecommunication software. It isfruitful to have mechanisms for specifying and reasoning about collections of MSCs so that errors can be detected even at the requirements level. We propose, accordingly, a notion of regularity for collections of MSCs and explore its basic properties. In particular, weprovide an automata-theoretic characterization of regular MSC languages in terms of finite-state distributed automata called boundedmessage-passing automata. These automata consist of a set of sequential processes that communicate with each other by sending andreceiving messages over bounded FIFO channels. We also provide alogical characterization in terms of a natural monadic second-orderlogic interpreted over MSCs.A commonly used technique to generate a collection of MSCs isto use a Message Sequence Graph (MSG). We show that the class oflanguages arising from the so-called locally synchronized MSGs constitute a proper subclass of the languages which are regular in our sense.In fact, we characterize the locally synchronized MSG languages asthe subclass of regular MSC languages that are finitely generated

A theory of regular MSC languages

Message sequence charts (MSCs) are an attractive visual formalism widely used to capture system requirements during the early design stages in domains such as telecommunication software. It is fruitful to have mechanisms for specifying and reasoning about collections of MSCs so that errors can be detected even at the requirements level. We propose, accordingly, a notion of regularity for collections of MSCs and explore its basic properties. In particular, we provide an automata-theoretic characterization of regular MSC languages in terms of finite-state distributed automata called bounded message-passing automata. These automata consist of a set of sequential processes that communicate with each other by sending and receiving messages over bounded FIFO channels. We also provide a logical characterization in terms of a natural monadic second-order logic interpreted over MSCs. A commonly used technique to generate a collection of MSCs is to use a hierarchical message sequence chart (HMSC). We show that the class of languages arising from the so-called bounded HMSCs constitute a proper subclass of the class of regular MSC languages. In fact, we characterize the bounded HMSC languages as the subclass of regular MSC languages that are finitely generated

A new simple method for labeling field crops with stable isotope tracers

Numerous systems have been used to label plants with 13C, which differ in design and complexity depending upon the desired experimental goals. However, most of these systems have generally been applied to greenhouse grown plants. Here, we report on a relatively simple 13C labeling system designed to label crops such as switchgrass (Panicum virgatum L.) grown in the greenhouse or small field plots. The main goals of this study were to validate the system and establish performance benchmarks. We constructed and field tested a simple design plexiglass chamber that was sealed at the soil level with a buried rubber apron. Chamber air was circulated through an infrared gas analyzer to monitor CO2 levels within the chamber. Provisions were made to control temperatures and minimize condensation inside the chamber during labeling. Control experiments using the empty chamber both under greenhouse and field settings showed that decline in CO2 levels was only due to plant CO2 absorption and not due to leakage. Results indicated that the system had generally suitable performance characteristics in both greenhouse and field settings. Isotope enrichment data from our studies revealed that switchgrass fixed 13CO2 that was injected into the chamber within 15-20 min labeling periods. The mean and standard deviation of leaf ᵹ13C values across nine plants enclosed in the chamber was 34 ± 8.9 and 96.1 ± 23.6 for the single and double labeling experiments, respectively. Results indicate that a chamber of this construction type can be effectively used also for labeling other crop plants

Effects of Parvovirus B19 Infection in Renal Transplant Recipients: A Retrospective Review of Three Cases

Parvovirus B19 (PVB19) is a DNA virus which causes clinically relevant infection in renal transplant recipients (RTR) leading to significant morbidity. Manifestations include erythropoietin resistant anemia, proteinuria, and glomerulosclerosis in the allograft. Severe infection may require administration of intravenous immunoglobulin, reduction in immunosuppression and transfusions. The major challenge in managing and preventing the infection in RTR involves the act of balancing the decreased level of immunosuppression and the risk of rejection. The objective of this article is to understand the importance of PVB19 infection and its outcome in RTR. We reviewed the medical records of three RTR with confirmed PVB19 infection and recorded patient information including demographics, clinical and laboratory data, management, and outcome. The average time of occurrence of PVB19 infection as transplant was 8.6 weeks and they presented with symptomatic anemia. Elevated creatinine values were noted in two of them. Following treatment, anemia improved and creatinine values returned to baseline. One of them developed an early relapse and had to be treated once again similarly. We emphasize the importance of maintaining a high index of suspicion for PVB19 infection in patients with anemia in the posttransplant phase, especially in patients on higher doses of immunosuppressants. Early and proper treatment can prevent worsening clinical condition and possible effects on the allograft

Theory of the Fano Resonance in the STM Tunneling Density of States due to a Single Kondo Impurity

The conduction electron density of states nearby single magnetic impurities, as measured recently by scanning tunneling microscopy (STM), is calculated, taking into account tunneling into conduction electron states only. The Kondo effect induces a narrow Fano resonance in the conduction electron density of states, while scattering off the d-level generates a weakly energy dependent Friedel oscillation. The line shape varies with the distance between STM tip and impurity, in qualitative agreement with experiments, but is very sensitive to details of the band structure. For a Co impurity the experimentally observed width and shift of the Kondo resonance are in accordance with those obtained from a combination of band structure and strongly correlated calculations.Comment: 4 pages, ReVTeX + 4 figures (Encapsulated Postscript), submitted to PR

Scattering Theory of Kondo Mirages and Observation of Single Kondo Atom Phase Shift

We explain the origin of the Kondo mirage seen in recent quantum corral Scanning Tunneling Microscope (STM) experiments with a scattering theory of electrons on the surfaces of metals. Our theory combined with experimental data provides the first direct observation of a single Kondo atom phase shift. The Kondo mirage at the empty focus of an elliptical quantum corral is shown to arise from multiple electron bounces off the walls of the corral in a manner analagous to the formation of a real image in optics. We demonstrate our theory with direct quantitive comparision to experimental data.Comment: 13 pages; significant clarifications of metho

Astrophysical S_{17}(0) factor from a measurement of d(7Be,8B)n reaction at E_{c.m.} = 4.5 MeV

Angular distribution measurements of $^2$H($^7$Be,$^7$Be)$^2$H and $^2$H($^7$Be,$^8$B)$n$ reactions at $E_{c.m.}\sim$~4.5 MeV were performed to extract the astrophysical $S_{17}(0)$ factor using the asymptotic normalization coefficient (ANC) method. For this purpose a pure, low emittance $^7$Be beam was separated from the primary $^7$Li beam by a recoil mass spectrometer operated in a novel mode. A beam stopper at 0$^{\circ}$ allowed the use of a higher $^7$Be beam intensity. Measurement of the elastic scattering in the entrance channel using kinematic coincidence, facilitated the determination of the optical model parameters needed for the analysis of the transfer data. The present measurement significantly reduces errors in the extracted $^7$Be(p,$\gamma$) cross section using the ANC method. We get $S_{17}$~(0)~=~20.7~$\pm$~2.4 eV~b.Comment: 15 pages including 3 eps figures, one figure removed and discussions updated. Version to appear in Physical Review

A modular focal plane detector system for the heavy ion reaction analyzer at NSC, New Delhi

A detector system has been developed for the focal plane of the HIRA. It consists of two independent detectors, a low-pressure multiwire proportional counter (LP-MWPC) followed by a split-anode ionization detector. Details of the design and test results are presented. Using slow preamplifiers, the position resolution is ≥1 mm and the time resolution is estimated to be 1.5 ns for the LP-MWPC. The ionization detector gives 2.4% energy resolution for 150 MeV 28Si scattered off a gold target and the ΔZ/Z obtained for 28Si+27Al is 1/42 for Z=14. Some results for fusion and transfer studies for the 48Ti+58Ni and 28Si+68Zn systems, respectively, at energies around the Coulomb barrier, are presented to highlight the performance of the detector system

3D Analysis of Ordered Porous Polymeric Particles using Complementary Electron Microscopy Methods

Highly porous particles with internal triply periodic minimal surfaces were investigated for sorption of proteins. The visualization of the complex ordered morphology requires complementary advanced methods of electron microscopy for 3D imaging, instead of a simple 2D projection: transmission electron microscopy (TEM) tomography, slice-and-view focused ion beam (FIB) and serial block face (SBF) scanning electron microscopy (SEM). The capability of each method of 3D image reconstruction was demonstrated and their potential of application to other synthetic polymeric systems was discussed. TEM has high resolution for details even smaller than 1 nm, but the imaged volume is relatively restricted (2.5 \u3bcm)3. The samples are pre-sliced in an ultramicrotome. FIB and SBF are coupled to a SEM. The sample sectioning is done in situ, respectively by an ion beam or an ultramicrotome, SBF, a method so far mostly applied only to biological systems, was particularly highly informative to reproduce the ordered morphology of block copolymer particles with 32\u201354 nm nanopores and sampling volume (20 \u3bcm)3