Channel and active component abstractions for WSN programming - a language model with operating system support

To support the programming of Wireless Sensor Networks, a number of unconventional programming models have evolved, in particular the event-based model. These models are non-intuitive to programmers due to the introduction of unnecessary, non-intrinsic complexity. Component-based languages like Insense can eliminate much of this unnecessary complexity via the use of active components and synchronous channels. However, simply layering an Insense implementation over an existing event-based system, like TinyOS, while proving efficacy, is insufficiently space and time efficient for production use. The design and implementation of a new language-specific OS, InceOS, enables both space and time efficient programming of sensor networks using component-based languages like Insense

Renin, endothelial no synthase and endothelin gene expression in the 2Kidney-1clip goldblatt model of long-term renovascular hypertension

<p>Abstract</p> <p>Objective</p> <p>Numerous reports have shown the influence of renin, nitric oxide (NO) and the endothelin (ET) systems for regulation of blood pressure and renal function. Furthermore, interactions between these peptides have been reported. Aim of our study was to investigate the relative contribution of these compounds in long-term renovascular hypertension/renal ischemia.</p> <p>Methods</p> <p>Hypertension/left-sided renal ischemia was induced using the 2K1C-Goldblatt rat model. Renal renin, ET-1, ET-3 and endothelial NO synthase (eNOS) gene expression was measured by means of RNAse protection assay at different timepoints up to 10 weeks after induction of renal artery stenosis.</p> <p>Results</p> <p>Plasma renin activity and renal renin gene expression in the left kidney were increased in the clipped animals while eNOS expression was unchanged. Furthermore, an increase in ET-1 expression and a decrease of ET-3 expression was detected in early stenosis.</p> <p>Conclusions</p> <p>While renin is obviously involved in regulation of blood pressure and renal function in unilateral renal artery stenosis, ET-1, ET-3 and endothelium derived NO do not appear to play an important role in renal adaptation processes in long-term renal artery stenosis, although ET-1 and ET-3 might be involved in short-term adaptation processes.</p

Efficient dynamic heap allocation of scratch-pad memory

&lt;p&gt;An increasing number of processor architectures support scratch-pad memory - software managed on-chip memory. Scratch-pad memory provides low latency data storage, like on-chip caches, but under explicit software control. The simple design and predictable nature of scratchpad memories has seen them incorporated into a number of embedded and real-time system processors. They are also employed by multi-core architectures to isolate processor core local data and act as low latency inter-core shared memory.&lt;/p&gt; &lt;p&gt;Managing scratch-pad memory by hand is time consuming, error prone and potentially wasteful; tools that automatically manage this memory are essential for its use by general purpose software. While there has been promising work in compile time allocation of scratch-pad memory, there will always be applications which require run-time allocation. Modern dynamic memory management techniques are too heavy-weight for scratch-pad management.&lt;/p&gt; &lt;p&gt;This paper presents the Scratch-Pad Memory Allocator, a light-weight memory management algorithm, specifically designed to manage small on-chip memories. This algorithm uses a variety of techniques to reduce its memory footprint while still remaining effective, including: representing memory both as fixed-sized blocks and variable-sized regions within these blocks; coding of memory state in bitmap structures; and exploiting the layout of adjacent regions to dispense with boundary tags for split and coalesce operations. We compare the performance of this allocator against Doug Lea's malloc implementation for the management of core-local and inter-core shared scratchpad memories under real world memory traces. This algorithm manages small memories efficiently and scales well under load when multiple competing cores access shared memory.&lt;/p&gt

Type-Based Publish/Subscribe

This paper presents type-based publish/subscribe, a new variant of the publish/subscribe paradigm. Producers publish message objects on a communication bus, and consumers subscribe to the bus by specifying the types of the objects they are interested in. Message objects are considered as first class citizens and are classified by their types, instead of arbitrarily fixed topics. By reusing the type scheme of the language to classify message objects, type-based publish/subscribe avoids any unnatural subscription scheme and provides for a seamless integration of a publish/subscribe middleware with the programming language. Type-based publish/subscribe has several quantifiable advantages over other publish/subscribe variants. In particular, the knowledge of the type of message objects enforces performance optimizations when combined with dynamic filters for content-based subscription. %from dynamically defined requirements. Our type-based publish/subscribe prototype is based on Distributed Asynchronous Collections (DACs), programming abstractions for publish/subscribe interaction. They are implemented using GJ, an extended Java compiler adding genericity to the Java language, and enable the expression of safely typed distributed interaction without requiring any generation of typed proxies

Operating system support for asymmetric multi-core architectures

As transistor densities increase, it is becoming ever more difficult to gain significant performance improvements in single processing core architectures therefore, processor designers are turning to multi-core processing architectures to increase overall performance. Several new architectures consist of multiple different processing cores, each specialised to a particular purpose. These asymmetric multi-core architectures can achieve significant performance and energy saving advantages, however, they are notoriously diffi- cult to program. We present research towards more effective Operating System (OS) support for asymmetric multi-core processor architectures. Section 2 outlines our proposed OS framework, aimed at enabling the effective use of asymmetric multi-core architectures by general purpose applications. Section 3 describes a novel memory management algorithm for on-core local memory, the first step towards the creation of our proof of concept implementation of this OS

The Asymptotic Configuration of Application Components in a Distributed System

Many distributed applications depend on explicit ordering to affect their lifecycle operations (start up, shutdown, re-configuration, etc.). Normally this procedure is carried out in a serialized manner. Consequently for applications containing large numbers of components, state and configuration changes are something to be avoided. They are costly, error prone and time consuming. This paper details an approach to application configuration which is specifically designed to address the issues of scale and reliability inherent in large distributed applications. The proposed architecture leads to applications which are ‘self healing’ in nature, and whose configuration mechanism is only loosely coupled to the number of components in a deployed system. Additionally, in applications where configuration changes can be planned in advance, the proposed mechanism can be used to make effective use of network resources in bandwidth limited environments

Enhanced expression of endothelin-1 gene may cause blood pressure independent vascular hypertrophy

Endothelin-1 (ET-1) has hypertrophic and mitogenic properties. Enhanced ET-1 gene expression in blood vessels of deoxycorticosterone acetate (DOCA)/ salt hypertensive rats and DOCA/salt spontaneously hypertensive rats (SHRs) was previously demonstrated. In this study, the effect on ET-1 gene expression in blood vessels and on vascular hypertrophy of the development of hypertension of DOCA/salt hypertensive rats, and that of salt and DOCA, were investigated in Sprague-Dawley rats and in SHRs. Increased abundance of ET-1 mRNA and a greater content of immunoreactive ET-1 were found with progression of hypertension in the aorta and the mesenteric arterial bed only in DOCA/salt hypertensive rats and in DOCA/salt SHRs. Vascular expression of ET-1 was not enhanced in DOCA- or salt-treated rats, even when blood pressure rose to a mean systolic pressure of 210 mm Hg. The media thickness and the media cross-sectional area of mesenteric resistance arteries of all groups of rats, including SHRs and Wistar-Kyoto (WKY) rats, exhibited a close correlation with systolic blood pressure. In DOCA/salt hypertensive rats after 5 weeks and in DOCA/salt SHRs in which significant over-expression of ET-1 was present in blood vessels, vascular morphometric parameters were excessive for the level of systolic blood pressure. In DOCA/salt hypertensive rats and DOCA/salt SHRs treated with the combined ETA/ ETB endothelin receptor antagonist bosentan, vascular morphometry correlated more closely with blood pressure, even though the blood pressure was only slightly lower than that of untreated rats. Lumen diameter correlated with blood pressure in all groups, including those overexpressing ET-1. These data support the hypothesis that ET-1 gene overexpression in blood vessels may accentuate vascular hypertrophy, but not remodeling, in DOCA/salt hypertensive rats and DOCA/salt SHRs in excess of that caused by blood pressure elevation per se

Diffusive phenomena in the charge and angular distributions for the reaction ^{197}Au + 620-MeV ^{86}Kr

The cross sections and the kinetic energy distributions of fragments with individually resolved atomic numbers have been measured as a function of angle. The variations in the Z distribution widths with angle and the change of the angular distributions from side peaked for Z's close to 36 to forward peaked for Z's far removed from 36 dramatically demonstrates the presence of diffusion of nucleons between the target and projectile

Evidence for diffusive relaxation along the mass asymmetry coordinate in the reaction 197Au + 620 MeV 86Kr

Nuclei have been identified by atomic number up to Z = 50 using ΔE-E telescopes. Kinetic energy spectra, charge and angular distributions have been measured from θlab = 10–80° . At angles removed from the grazing, a single peak with a mean energy somewhat below the calculated Coulomb energy is observed for all elements. Near the grazing angle, a much broader peak appears, which extends from near elastic energies down to the Coulomb barrier. The charge distributions are peaked near the projectile Z and demonstrate a strong shape dependence on the angle of observation. The angular distributions for elements near the projectile are strongly side peaked; however, as Z is increased or decreased from Z = 36, they gradually become forward peaked. The dependence of the charge and angular distributions on energy dissipation is discussed as well as the patterns observed in the two-dimensional Wilczynski plots. Diffusion model calculations reproduce the experimental data both qualitatively and quantitatively. This successful application of the diffusion model, which was originally developed to explain N, Ne and Ar induced reactions, to the present system is strong evidence that no essential differences exist between the “quasi-fission” process observed in Kr bombardments of heavy targets and the deep-inelastic phenomena seen with lighter ions

Cytosolic calcium changes induced by angiotensin II in neonatal rat atrial and ventricular cardiomyocytes are mediated via angiotensin II subtype 1 receptors

We determined the effects of angiotensin II (Ang II) on cytosolic free calcium concentrations ([Ca2+]i) in the absence and presence of the selective angiotensin subtype 1 (AT1) receptor antagonist losartan or the selective AT2 antagonist PD 123319 in cultured neonatal rat atrial and ventricular cardiomyocytes. We also assessed Ang II receptor density, affinity, and mRNA expression. [Ca2+]i was measured in single cells microphotometrically and by fluorescent digital imaging with fura 2 methodology. Receptor parameters were assessed by competitive binding studies with 125I-[Sar1,Ile8]Ang II in the presence of increasing concentrations of [Sar1,Ile8]Ang II, losartan, and PD 123319. AT1 receptor (types AT1A and AT1B) mRNA abundance was measured by reverse transcription–polymerase chain reaction. Ang II produced concentration-dependent increases in [Ca2+]i. Basal [Ca2+]i values in atrial and ventricular cells were similar but Ang II (10−9 mol/L)–induced [Ca2+]i changes were significantly greater in atrial compared with ventricular cells. Ang II responses were blocked by losartan (10−7 mol/L) but not PD 123319 (10−7 mol/L). Binding studies demonstrated a single class of high-affinity Ang II binding sites on cardiomyocyte membranes (Kd=0.71±0.11 μmol/L). 125I-[Sar1,Ile8]Ang II was displaced by losartan but not by PD 123319. AT1 receptor mRNA was detected by reverse transcription–polymerase chain reaction in cells from atria and ventricles. In atrial cardiomyocytes, both AT1A and AT1B receptor genes were expressed, whereas in ventricular cardiomyocytes, only the AT1A receptor gene was expressed. These data demonstrate that neonatal cardiomyocytes possess Ang II receptors of the AT1 receptor subtype that are linked to [Ca2+]i signaling pathways. The different Ang II–induced [Ca2+]i responses between atrial and ventricular cells may be related to differences in the distribution of AT1 receptor subtype subvariants