Substantial Leakage Research Articles

Leakage-efficient design of value predictors through state and non-state preserving techniques

In the last decade computer engineers have faced changes in the way microprocessors are designed. New microprocessors do not only need to be faster than the previous generation, but also be feasible in terms of energy consumption and thermal dissipation. Recently, a new challenge appeared for computer engineers, the static power consumption. As process technology advances toward deep submicron, the static power component becomes a serious problem, especially for large on-chip array structures such as caches or prediction tables, and it must be taken into consideration. We can fight to reduce leakage power in two different ways: we can switch off the structure, reducing its leakage to zero but losing its contents (non-state preserving techniques), or we can lower its voltage (state preserving techniques), obtaining less savings but being able to restore the state of the structure in a reasonable time. Data dependences are one of the key factors that limit performance in modern microprocessors. Value Prediction (VP) is a paradigm that exploits value locality in order to predict the output of an instruction, overcoming data dependences. The more accurate the predictor, the more performance is obtained, at the expense of becoming a potential source of power consumption and a thermal hot spot. In this work we propose a leakage-efficient design of traditional Value Predictors (Stride, FCM, and DFCM) based on the fact that many VP entries remain unused during long periods of time before being eventually evicted. By applying both state and non-state preserving techniques, the unused entries are disabled obtaining substantial leakage energy reductions (50---80% depending on the configuration and predictor type).

Shear-layers in magnetohydrodynamic spherical Couette flow with conducting walls

We consider the steady axisymmetric motion of an electrically conducting fluid contained within a spherical shell and permeated by a centred axial dipole magnetic field, which is strong as measured by the Hartmann number M. Slow axisymmetric motion is driven by rotating the inner boundary relative to the stationary outer boundary. For M ≫ 1, viscous effects are only important in Hartmann boundary layers adjacent to the inner and outer boundaries and a free shear-layer on the magnetic field line that is tangent to the outer boundary on the equatorial plane of symmetry. We measure the ability to leak electric current into the solid boundaries by the size of their relative conductance ɛ. Since the Hartmann layers are sustained by the electric current flow along them, the current inflow from the fluid mainstream needed to feed them increases in concert with the relative conductance, because of the increasing fraction ℒ of the current inflow leaked directly into the solids. Therefore the nature of the flow is sensitive to the relative sizes of ɛ−1 and M.The current work extends an earlier study of the case of a conducting inner boundary and an insulating outer boundary with conductance ɛo = 0 (Dormy, Jault & Soward, J. Fluid Mech., vol. 452, 2002, pp. 263–291) to other values of the outer boundary conductance. Firstly, analytic results are presented for the case of perfectly conducting inner and outer boundaries, which predict super-rotation rates Ωmax of order M1/2 in the free shear-layer. Successful comparisons are made with numerical results for both perfectly and finitely conducting boundaries. Secondly, in the case of a finitely conducting outer boundary our analytic results show that Ωmax is O(M1/2) for ɛo−1 ≪ 1 ≪ M3/4, O(ɛo2/3M1/2) for 1 ≪ ɛo−1 ≪ M3/4 and O(1) for 1 ≪ M3/4 ≪ ɛo−1. On increasing ɛo−1 from zero, substantial electric current leakage into the outer boundary, ℒo ≈ 1, occurs for ɛo−1 ≪ M3/4 with the shear-layer possessing the character appropriate to a perfectly conducting outer boundary. When ɛo−1 = O(M3/4) the current leakage is blocked near the equator, and the nature of the shear-layer changes. So, when M3/4 ≪ ɛo−1, the shear-layer has the character appropriate to an insulating outer boundary. More precisely, over the range M3/4 ≪ ɛo−1 ≪ M the blockage spreads outwards, reaching the pole when ɛo−1 = O(M). For M ≪ ɛo−1 current flow into the outer boundary is completely blocked, ℒo ≪ 1.

The Unequal Benefits of Fuel Subsidies: A Review of Evidence for Developing Countries

This paper reviews evidence on the impact of fuel subsidy reform on household welfare in developing countries. On average, the burden of subsidy reform is neutrally distributed across income groups; a $0.25 decrease in the per liter subsidy results in a 6 percent decrease in income for all groups. More than half of this impact arises from the indirect impact on prices of other goods and services consumed by households. Fuel subsidies are a costly approach to protecting the poor due to substantial benefit leakage to higher income groups. In absolute terms, the top income quintile captures six times more in subsidies than the bottom. Issues that need to be addressed when undertaking subsidy reform are also discussed, including the need for a new approach to fuel pricing in many countries.

The Unequal Benefits of Fuel Subsidies: A Review of Evidence for Developing Countries

This paper reviews evidence on the impact of fuel subsidy reform on household welfare in developing countries. On average, the burden of subsidy reform is neutrally distributed across income groups; a $0.25 decrease in the per liter subsidy results in a 6 percent decrease in income for all groups. More than half of this impact arises from the indirect impact on prices of other goods and services consumed by households. Fuel subsidies are a costly approach to protecting the poor due to substantial benefit leakage to higher income groups. In absolute terms, the top income quintile captures six times more in subsidies than the bottom. Issues that need to be addressed when undertaking subsidy reform are also discussed, including the need for a new approach to fuel pricing in many countries.

Field-Effect Control of Electroosmotic Pumping Using Porous Silicon–Silicon Nitride Membranes

Field-effect control of electroosmotic (EO) flow, which has been demonstrated on single microchannels, provides a novel method to modulate the zeta potential and, therefore, the EO flow through a porous membrane. To realize field-effect control of EO pumping with a membrane, a SiN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> -coated porous silicon membrane was designed and fabricated. The heavily doped silicon core was used as a conducting electrode to apply the transverse gate potential, which modulates the zeta potential of the channel walls and, thereby, the EO flow rate with constant externally applied electric fields along the channels. We observed significant electrolytic-rectification effect, i.e., for gate voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> ) < 0, a substantial current leakage through the SiN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> was observed, whereas negligible leakage current was detected for V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> > 0. Significant EO flow control, nearly 70% reduction in flow velocity, was observed for positive gate bias, while only 15 % flow-velocity enhancement was observed for negative gate bias of similar magnitude. This first demonstration of field-effect control on porous membranes opens the door for making high-flow rate EO pumps with porous membranes of low zeta potential materials.

Factor and Cluster Analyses of Water Chemistry in and around a Large Rockfill Dam: Implications for Water Leakage

Based on water chemistry data, a rockfill dam in South Korea was investigated to identify major parts of substantial dam water leakage. Sinkholes in the dam crest and abnormal water leakage through the dam were observed since the first impounding of the dam. Previous investigations, including observational drillings, hydraulic tests, geophysical surveys, and tracer tests, revealed the development of a high permeability zone in the clay core and an abnormally high phreatic line zone in the left embankment. Sequential tracer tests provided further evidence of locations of preference and rapid water leakage pathways. In this study, we examined the usefulness of water chemistry data to confirm previous findings of water leakage. Factor analysis of the water chemistry data revealed major processes controlling the chemical composition, which include the wash-out and successive dissolution of fill materials in the dam interior, interaction between percolating water and dam core materials, and contamination of seeping water by grouting materials and previous tracer tests. Distinct spatial distribution of similar chemical groups was illustrated by cluster analysis and confirmed the location of major water leakage at the left abutment adjoining the spillway.

The global diversion of pharmaceutical drugs

This paper explores India's role in the world illicit opiate market, particularly its role as a producer. India, a major illicit opiate consumer, is also the sole licensed exporter of raw opium: this unique status may be enabling substantial diversion to the illicit market. Participant observation and interviews were carried out at eight different sites. Information was also drawn from all standard secondary sources and the analysis of about 180 drug-related criminal proceedings reviewed by Indian High Courts and the Supreme Court from 1985 to 2001. Diversion from licit opium production takes place on such a large scale that India may be the third largest illicit opium producer after Afghanistan and Burma. With the possible exceptions of 2005 and 2006, 200-300 tons of India's opium may be diverted yearly. After estimating India's opiate consumption on the basis of UN-reported prevalence estimates, we find that diversion from licit production might have satisfied a quarter to more than a third of India's illicit opiate demand to 2004. India is not only among the world's largest consumer of illicit opiates but also one of the largest illicit opium producers. In contrast to all other illicit producers, India owes the latter distinction not to blatantly illicit cultivation but to diversion from licit cultivation. India's experience suggests the difficulty of preventing substantial leakage, even in a relatively well-governed nation.

Determinants of household supply of labour in food-for-work programme in Tigray, Ethiopia

We study the factors that determine the household supply of labour in food-for-work (FFW) projects that seek to address food insecurity and help capital formation in development. Based on data from a survey conducted in 2003 in Tigray, Ethiopia, our probit analysis identifies factors that significantly affect the household decision to participate in FFW programmes. We correct for selection bias, and estimate total and excess supply of FFW labour. Our finding of substantial leakages in targeting that allow relatively well-off households to obtain FFW employment yield important implications for the prevailing FFW wage. We also argue that FFW programmes will be more effective if they are designed to account for geographic heterogeneity in such factors as male to female labour participation differences and the incidence of debilitating diseases.

An Historical Overview of Opium Cultivation and Changing State Attitudes towards the Crop in India, 1878–2000 A.D.

The opium trade yielded enormous profits to the British imperialists during the nineteenth century and the first half of the twentieth century. While China was forcibly converted into the largest market for opium by the British from the early nineteenth century, India emerged as a fertile ground for the cultivation of poppy and manufacturing of opium under British monopoly during the colonial period. British rule in India and British control of the Indian princely states ensured a steady supply of opium from India to China, thereby facilitating the transfer of economic surplus from China to Britain. So profitable was the opium trade that the cultivation and production of opium in India was carefully monitored by the colonial state. The aim of the colonial state in India was profit maximization from the production and sale of opium but gradually, under growing international pressure after the First World War, feeble measures were contemplated to scale down the opium trade. The Indian nationalists, however, were firmly opposed to opium and tirelessly criticized the colonial discourse and policy on opium. Following this, after independence, the government of India became committed to the imposition of severe restrictions on poppy cultivation and opium production. From 1947 poppy would be grown in India under strict government control and only for medicinal purposes. Thus opium production was subjected to state monopoly during the colonial period and in independent India for different reasons. On the other hand opium smuggling, as a breach of state monopoly, remained widespread during the colonial period. Similarly, and despite the costly efforts made by the post-colonial state in India, substantial leakages into the illicit opium market have been reported by the sources since independence. This article narrates the story of attempted state control of poppy cultivation and opium production in modern India in the context of the challenges posed to the eradication of opium addiction by the politics of the Cold War and globalization eras

In Al N ∕ Ga N metal-oxide-semiconductor high electron mobility transistor with Al2O3 insulating films grown by metal organic chemical vapor deposition using Ar and NH3 carrier gases

Al 2 O 3 thin films were deposited by a metal organic chemical vapour deposition on InAlN∕GaN heterostructures using Ar or NH3 as a carrier gas. Effects of NH3 and Ar carrier gases on the electrical and structural properties of Al2O3∕InAlN∕GaN HEMT devices were investigated by current voltage, current collapse, and Auger electron spectroscopy measurements. Al2O3 deposited using Ar as a carrier gas leads to a substantial gate leakage current reduction with no increase of the current collapse compare to Schottky gate based HEMT. On the other hand, HEMT electrical performance shows degradation if NH3 carrier gas is used. Similarly, Auger electron spectroscopy revealed presence of carbon on InAlN surface when NH3 carrier gas was applied. It is suggested that the formation of carbon-related traps on the InAlN surface takes place in the early stages of the Al2O3 deposition with NH3 carrier gas that strongly influences the HEMT performance.

Studies of injection ports of permanent expandable breast implants

It has previously been questioned if the injection port of soft-tissue expanders is a source of leakage. However, several laboratory studies have concluded that the port is safe. A former quality assessment of our one-stage breast reconstructive procedures showed, that suspicion of leakage led to the removal of the injection port in 12% of the cases. With this level of inconsistency with previous laboratory studies, we found a need to conduct a separate study in order to confirm the true cause of leakage. Thirteen consecutively removed McGhan Style 150 injection ports were examined for leakage by increasing intraluminal pressure. Eight of the 13 ports had been removed because of discomfort due to the subcutaneous placement. Three of these eight ports showed substantial leakage (up to 14.55 ml/hour) at pressures attainable under normal in vivo circumstances. Five of the 13 ports had been removed due to clinical leakage. All five showed substantial leakage in the experimental setting (up to 19.65 ml/hour). Comparing the placement of the leaking puncture holes with the construction of the port, it seems that the leaking puncture holes are the result of peripheral perforations escaping the self-sealing material in the port, while still allowing injection of saline. The study shows clinical and experimental evidence of leakage from the McGhan Style 150 injection port, which is contrary to other similar laboratory studies. However, in those studies the needles were inserted at the apex of the port membrane, while our study shows that this is not in accordance with a clinical setting, where perforation may be all over the port. It is concluded that extreme care should be taken in the clinical setting only to perpendicularly perforate the apex of the injection port membrane. Peripheral perforation of the port may result in leakage of saline.

Assessment of lake–groundwater interactions and anthropogenic stresses, using numerical groundwater flow model, for a Rift lake catchment in central Ethiopia

AbstractA steady‐state groundwater flow model (MODFLOW) was used to study lake and groundwater interactions in a complex rift volcanic catchment. It also was used to assess the effects of water pumping from wells, and of variable recharge rates associated with climate and lake level changes, on the dynamics of the volcanic aquifers surrounding Lake Awassa. The model simulations were made after first developing a reasonable conceptual model, on the basis of conventional hydrogeological mapping, pumping test and hydrometeorological data analyses, and from ancillary information obtained from hydrochemical and isotope techniques. The model results indicated that the lakes and Rift aquifers are fed by large groundwater inputs that originate in the highlands. The lakes and rivers have important roles in recharging the aquifers in some locations. Lake Awassa receives a major groundwater inflow from its southern and eastern shorelines, while substantial water leakage from the lake occurs along the northern shoreline. The annual groundwater outflow from the catchment is estimated to 52.5 × 106 m3. Scenario analyses revealed that increasing the current pumping rate from wells by fourfold will substantially reduce the groundwater level substantially, although the regional flow pattern would remain the same. There appears to be no immediate danger to the Rift aquatic environment from the current water pumping rate. Drying the small Lake Shalo and associated swamps, however, will cause a large change in the water balance of the larger Lake Awassa. Slight changes in groundwater recharge can cause large differences in groundwater levels for most of the Rift caldera floor far from the lake shores. This study provides a reasonable foundation for developing detailed transient predictive models, which can then readily be used as a decision support tool for development and implementation of sustainable water resources practices.

Intraprocedural Adjacent Level Compression Fracture During Vertebroplasty Secondary to Cement Leakage into the Disc Space

An elderly female underwent three level vertebroplasty for painful compression fractures of the thoracolumbar junction. During injection of the third level, she developed severe pain resulting from an acute adjacent level fracture secondary to substantial cement leakage into the disc space. This was recognized and treated immediately with vertebroplasty resulting in complete pain relief. To our knowledge, this is the first reported case of intraprocedural compression fracture secondary to cement leakage into the disc space. Keywords: Vertebroplasty, cement leakage, subsequent compression fractures, methylmethacrylate

Reduction of arginase I activity and manganese levels in the liver during exposure of rats to methylmercury: a possible mechanism

The toxicity of methylmercury (MeHg) is, in part, thought to be due to its interaction with thiol groups in a variety of enzymes, but the molecular targets of MeHg are poorly understood. Arginase I, an abundant manganese (Mn)-binding protein in the liver, requires Mn as an essential element to exhibit maximal enzyme activity. In the present study, we examined the effect of MeHg on hepatic arginase I in vivo and in vitro. Subcutaneous administration of MeHg (10 mg/kg) for 8 days to rats resulted in marked suppression of arginase I activity. With purified arginase I, we found that interaction of MeHg with arginase I caused the aggregation of arginase I as evaluated by centrifugation and subsequent precipitation, and then the reduction of catalytic activity. Experiments with organomercury column confirmed that arginase I has reactive thiols that are covalently bound to organomercury. While MeHg inhibited arginase I activity, Mn ions were released from this enzyme. These results suggest that MeHg-mediated suppression of hepatic arginase I activity in vivo is, at least in part, attributable to covalent modification of MeHg or substantial leakage of Mn ions from the active site.

Membrane fouling and process performance of forward osmosis membranes on activated sludge

An innovative osmotic membrane bioreactor (OMBR) is currently under development, based on forward osmosis (FO) driven by an osmotic pressure difference. For the OMBR to be both technically and economically viable, the performance of the FO membranes has to be sufficiently high, while membrane fouling and draw solution leakage has to be low. The effect of temperature, membrane type, membrane orientation, type and concentration of draw solution was investigated to optimize FO membrane performance using deionised water. Membrane fouling and draw solution leakage was investigated in this work by laboratory scale FO experiments using an activated sludge solution from a membrane bioreactor (MBR). The best FO performance with an activated sludge solution was found with a FO-type membrane ( J = 6.2 l/m 2 h at 20 ± 2 °C with 0.5 M NaCl corresponding to π = 24 bar). Draw solutions from salts consisting of monovalent ions (NaCl and NaNO 3) performed better than salts consisting of bivalent ions (MgSO 4 and ZnSO 4), while the flux of the FO membrane were non-linearly related to the concentration of the draw solution. Internal concentration polarization did hamper the FO performance as a result of the thickness and structure of the porous substructure of the investigated membranes. Both reversible and irreversible membrane fouling were not found during the FO experiments using activated sludge solutions. Furthermore no substantial draw solution leakage was found for the FO membranes at various draw solution concentrations for different draw solutions.

Liposome-Mediated Triggering of Complement Cascade

The complement system is one of the most ancient defense strategies, which serves as an important effector arm of both innate and acquired immunity. Three consequences ensue when liposomes trigger the complement system in the blood. These are priming of the vesicular surface by opsonic complement fragments for recognition and clearance by phagocytic cells, generation of anaphylatoxins, and chemoattractants, which may subsequently initiate pseudoallergy-related anaphylaxis in sensitive individuals, and insertion of the lytic complex C5b-9 into the liposomal bilayer, which may result in substantial leakage of vesicular encapsulated aqueous cargo. Here, we briefly review and discuss the molecular basis of complement activation by phospholipid vesicles and reflect on sensitive and rapid Enzyme-Linked Immunosorbent Assays (ELISA) for assessing and monitoring liposome-mediated triggering of a complement cascade in human serum.

Fabrication of Organic Thin-Film Transistors Based on High Dielectric Nanocomposite Insulators

Organic thin-film-transistors (OTFTs) with solution-processed high dielectric gate insulators were fabricated. The gate insulators were made of high dielectric TiO2 nanoparticles dispersed uniformly in a polymer matrix of nylon 6 which is known to align liquid crystal molecules. It was found that the nanocomposite insulator in a pentacene-based OTFT reduces the operating voltage but it produces substantial current leakage. A buffer layer of polyvinylphenol on the top of the nanocomposite layer was found to block the leakage current and to increase significantly the carrier mobility as well as the current on-off ratio.

Finite Element Solution of Inertia Influenced Flow in Thin Fluid Films

Abstract The aim of this paper is to present a numerical model to compute laminar, turbulent, and transitional incompressible fluid flows in thin lubricant films where inertia effects cannot be neglected. For this purpose, an averaged inertia method is used. A numerical scheme based on the finite element method is presented to solve simultaneously the momentum and continuity equations. The numerical model is then validated by confronting it with previously published analytical, experimental, and numerical results. Particular attention is devoted to analyzing the numerical conservation of mass and momentum. The influence of mesh size on numerical precision is also analyzed. Finally, the model is applied to a misaligned hydrostatic seal. These seals operate with a substantial leakage flow, where nonlaminar phenomena occur. The influence of inertia and misalignment of the faces on the seal behavior is analyzed through a comparison with an inertialess solution. Significant differences are observed for high values of the tilt angle when the flow is nonlaminar. Inertia effects increase when the flow is laminar.

Evaluation of tritium behavior in concrete

Concrete walls used in a fusion reactor or a tritium handling facility have the important role of separating the atmosphere in a facility from environmental air, since substantial tritium leakage is possible from a tritium system to the atmosphere of a tritium handling facility. Therefore, it is necessary to understand the transfer behavior of tritium through concrete. The experiments of this study were performed to observe the change of the tritium distribution with time in columns made of cement paste, mortar or concrete. It was found that exposure of the surface of concrete materials to HTO vapor for two months produced tritium permeation to the depth of 30 mm. Estimation of tritium penetration behavior was also performed in this study by applying adsorption, desorption and isotope exchange reactions and the estimated tritium profile was in good agreement with observed values.

Dual regulation of astrocyte gap junction hemichannels by growth factors and a pro‐inflammatory cytokine via the mitogen‐activated protein kinase cascade

Evidence that glutamate and ATP release from astrocytes can occur via gap junction hemichannels (GJHCs) is accumulating. However, the GJHC is still only one possible release mechanism and has not been detected in some studies, although this may be because the levels were below those detectable by the system used. Because of these conflicting results, we hypothesized that release from astrocyte GJHCs might depend on different astrocyte states, and screened for factors affecting astrocyte GJHC activity by measuring fluorescent dye leakage via GJHCs using a conventional method for GJHC acivation, i.e. removal of extracellular divalent cations. Astrocytes cultured in Dulbecco's minimal essential medium containing 10% fetal calf serum, a medium widely used for astrocyte studies, did not show dye leakage, whereas those cultured in a defined medium showed substantial dye leakage, which was confirmed pharmacologically to be due to GJHCs and not to P2x7 receptors. EGF and bFGF inhibited the GJHC activity via the mitogen-activated protein kinase cascade, and the effect of the growth factors was reversed by interleukin-1beta. These factors altered GJHC activity within 10 min, but did not affect connexin 43 expression. GJHC activity in hippocampal slice culture preparations was measured using the same methods and found to be regulated in a similar manner. These results indicate that astrocyte GJHC activity is regulated by brain environmental factors.