Structural Encoding of Static Single Assignment Form

AbstractStatic Single Assignment (SSA) form is often used as an intermediate representation during code optimization in Java Virtual Machines. Recently, SSA has successfully been used for bytecode verification. However, constructing SSA at the code consumer is costly. SSA-based mobile code transport formats have been shown to eliminate this cost by shifting SSA creation to the code producer. These new formats, however, are not backward compatible with the established Java class-file format. We propose a novel approach to transport SSA information implicitly through structural code properties of standard Java bytecode. While the resulting bytecode sequence can still be directly executed by traditional Virtual Machines, our novel VM can infer SSA form and confirm its safety with virtually no overhead

An iron-based beverage, HydroFerrate fluid (MRN-100), alleviates oxidative stress in murine lymphocytes in vitro

BackgroundSeveral studies have examined the correlation between iron oxidation and H2O2 degradation. The present study was carried out to examine the protective effects of MRN-100 against stress-induced apoptosis in murine splenic cells in vitro. MRN-100, or HydroFerrate fluid, is an iron-based beverage composed of bivalent and trivalent ferrates.MethodsSplenic lymphocytes from mice were cultured in the presence or absence of MRN-100 for 2 hrs and were subsequently exposed to hydrogen peroxide (H2O2) at a concentration of 25 μM for 14 hrs. Percent cell death was examined by flow cytometry and trypan blue exclusion. The effect of MRN-100 on Bcl-2 and Bax protein levels was determined by Western blot.ResultsResults show, as expected, that culture of splenic cells with H2O2 alone results in a significant increase in cell death (apoptosis) as compared to control (CM) cells. In contrast, pre-treatment of cells with MRN-100 followed by H2O2 treatment results in significantly reduced levels of apoptosis. In addition, MRN-100 partially prevents H2O2-induced down-regulation of the anti-apoptotic molecule Bcl-2 and upregulation of the pro-apoptotic molecule Bax.ConclusionOur findings suggest that MRN-100 may offer a protective effect against oxidative stress-induced apoptosis in lymphocytes

Scheduling Parallel Loops for Processing Linear Lists

Imperative languages such as C, FORTRAN 90 or Modula-2 are being increasingly used to program parallel computers. By using these languages, the normal programming environment is disposable, however runtime deteriorates. The problem is the existence of pointers and dynamic data structures, which prevent effective parallelization methods. Here we demonstrate a new technique for shared memory systems. The list approach with pipeline method works on a linear list in parallel. After a theoretical valuation the practical operation on a KSR1 system will be discussed. 1. Introduction For the programming of parallel computers, the use of normal imperative languages like C, Fortran 90 or Modula2 is becoming more frequent. This is true in explicit parallel programming and even in automatic parallelization. But today's compiler systems---for example the SUIF system [1]---are not able to handle pointer variables or dynamic data structures entirely. The reason is the lack of sufficient data depende..

LogP Modelling of List Algorithms

We present techniques for distributing lists for processing on distributed and shared memory architectures. The LogP cost model is extended for evaluating the schedules for the given problems and architectures. We consider both bounded and unbounded lists. The theoretical results are confirmed by measurements on a KSR-1. I. Introduction Most parallel algorithms operate on arrays because they are easy to distribute and redistribute, particularly, if their size is fixed, (c.f. [9]). However, arrays are not appropriate for a wide range of problems, e.g. for algorithms on graphs. But the lack of efficient distribution techniques of the elements forces programmers to use arrays instead of lists even if the latter is a better choice from a designer's point of view. The problem is even worse for the parallelization of sequential code, as the programmer usually does not consider parallel execution. The obvious solution, which would be the list converted into an array before distribution, is..

Data Dependence Analysis of Assembly Code

: Determination of data dependences is a task typically performed with highlevel language source code in today's optimizing and parallelizing compilers. Very little work has been done in the field of data dependence analysis on assembly language code, but this area will be of growing importance, e.g. for increasing Instruction Level Parallelism. A central element of a data dependence analysis in this case is a method for memory reference disambiguation which decides whether two memory operations may/must access the same memory location. In this paper we describe a new approach for determination of data dependences in assembly code. Our method is based on a sophisticated algorithm for symbolic value propagation, and it can derive value-based dependences between memory operations instead of just address-based dependences. We have integrated our method into the SALTO system for assembly language optimization. Experimental results show that our approach greatly improves the accuracy of the..

A kinetic study of UO2 dissolution and H2O2 stability in the presence of groundwater ions.

Current reactors spent nuclear UO2 fuel, that will probably enter geologic formations for disposal, is assumed to get into contact with groundwater of a repository earliest after several thousands of years. After this time, its alpha activity will be still high enough to induce a process of water radiolysis that leads to production of oxidants and, probably, to the oxidative dissolution of the material, that could start a mobilisation of radiotoxic nuclides. The main oxidant produced during this process would be hydrogen peroxide (H2O2), which is thermodynamically unstable and can decompose during reactions with certain groundwater ions. Information on the stability of H2O2 is therefore important for assessing the behaviour of the material in the repository. We investigated the stability of H2O2 and the correlated dissolution of U from UO2 as a function of the concentration of H2O2 and of the groundwater ions carbonate, sulphate, and silicate. Decomposition of H2O2 was measured in the presence and absence Of UO2(cr). We monitored the concentrations of H2O2, U-diss, groundwater ions, O-2 (diss), and the pH in aqueous solution under Ar atmosphere. The lowest stabilities (in average) for H2O2 were found in carbonate solutions. When comparing the effect of carbonate systems containing UO2(cr) to carbonate solutions without a solid phase, we found that in some of the homogeneous tests H2O2 was consumed faster. This effect was not observed with the other groundwater ions. Also, U dissolution rates were significantly lower in the carbonate experiments than in those with sulphate or silicate. The results suggest that a radical-controlled mechanism (similar to the Halpern - Smith-mechanism of dissolved U(IV) oxidation) takes place at the UO2 surface during dissolution. The hypothesis is supported by ESR measurements on hydroxyl radical scavenging by the carbonate ion

A Kinetic Study of UO2 Dissolution and H202 Stability in the Presence of Groundwater Ions

Current reactors spent nuclear UO2 fuel that will probably be directly disposed in geologic formations is assumed to get into contact with groundwater of a repository earliest after several thousands of years. After this time, its alpha activity will be still high enough to induce a process of water radiolysis that leads to production of oxidants and, probably, to the oxidative dissolution of the material, that would start a mobilisation of radiotoxic nuclides. The main oxidant produced during this process would be hydrogen peroxide (H2O2), which is thermodynamically unstable and can decompose during reactions with certain groundwater ions. Information on the stability of H2O2 is therefore important for assessing the behaviour of the material in the repository.JRC.E.3-Materials researc