bluuebunny/crossref_metadata_2025 huggingface dataset:
Method and Detailed Analysis of Individual Hydrocarbon Species From Diesel Combustion Modes and Diesel Oxidation Catalyst
Authors: Han Manbae , Bohac Stanislav V. , Jacobs Timothy J. , Assanis Dennis N.
Published: March 2009

An undiluted exhaust hydrocarbon (HC) speciation method, using flame ionization detector (FID) gas chromatographs (GC), is developed to investigate HC species from conventional and low-temperature premixed charge compression ignition (PCI) combustion, from pre- and post-diesel oxidation catalyst (DOC) exhaust. This paper expands on previously reported work by describing in detail the method and effectiveness of undiluted diesel exhaust speciation and providing a more detailed analysis of individual HC species for conventional and PCI diesel combustion processes. The details provided regarding the effectiveness of the undiluted diesel exhaust speciation method include the use of a fuel response factor (RF) for HC species quantification and demonstration of its linearity, detection limit, accuracy and precision. The listing of individual HC species provides not only the information needed to design surrogate exhaust mixtures used in reactor tests and modeling studies, but also sheds light on PCI combustion and DOC characteristics. Significantly increased engine-out concentrations of acetylene, benzene and toluene support the theory that net soot reduction associated with PCI combustion occurs due to the reduction of soot formation from soot precursors. DOC oxidation behavior differs depending on the combustion characteristics, which change exhaust species and temperature.
Blow-By Truck Application: Electrically Driven Cone Stack Separator for Crankcase Ventilation
Authors: Kissner Gerd , Sauter Hartmut
Published: March 2009

Dealing with the blow-by gas from reciprocating engine is a bigger challenge nowadays due to strict emission control laws and design limitations. Blow-by gas originates between the piston or piston rings and the cylinder wall and is charged with oil when it leaves the crankcase. In a closed crankcase ventilation system these blow-by gases are drawn from the crankcase into the air intake. The oil mist separator (OMS) retains a fraction of the liquid oil and returns the retained oil fraction back to the oil sump. Thus, the oil mist separator reduces oil consumption and emissions. Electrically driven cone stack separators have high separation efficiency, small differential pressure, arbitrary mounting position and low power consumption. In addition to that, the electrically driven cone stack separator has also advantageous control characteristics. Since commercial motor vehicles already have high electrical system requirements a Mechatroic concept is presented here which was developed to be maintenance-free over the lifetime of the engine. This is achieved by detailed design and choice of special materials. In this paper, the construction and application of the novel oil mist separator system for trucks are discussed in detail.
Modeling Cyclic Variability in Spark-Assisted HCCI
Authors: Daw C. Stuart , Edwards K. Dean , Wagner Robert M. , Green Johney B.
Published: March 2009

Spark assist appears to offer considerable potential for increasing the speed and load range over which homogeneous charge compression ignition (HCCI) is possible in gasoline engines. Numerous experimental studies of the transition between conventional spark-ignited (SI) propagating-flame combustion and HCCI combustion in gasoline engines with spark assist have demonstrated a high degree of deterministic coupling between successive combustion events. Analysis of this coupling suggests that the transition between SI and HCCI can be described as a sequence of bifurcations in a low-dimensional dynamic map. In this paper we describe methods for utilizing the deterministic relationship between cycles to extract global kinetic rate parameters that can be used to discriminate multiple distinct combustion states and develop a more quantitative understanding of the SI-HCCI transition. We demonstrate the application of these methods for indolene-containing fuels and point out an apparent HCCI mode switching not previously reported. Our results have specific implications for developing dynamic combustion models and feedback control strategies that utilize spark-assist to expand the operating range of HCCI combustion.
Cold Engine Transient Fuel Control Experiments in a Port Fuel Injected CFR Engine
Authors: Hamilton Leonard J. , Cowart Jim S.
Published: March 2009

Air-fuel mixture preparation is particularly challenging during cold engine throttle transients due to poor fuel vaporization and transport delays in port fuel injected (PFI) engines. In this study, a PFI Cooperative Fuels Research engine is used to evaluate torque and measure in cylinder and exhaust CO, CO2 and unburned hydrocarbons during throttle transients at various early stages of engine warm-up. Fast flame ionization detectors and non-dispersive infra-red fast CO and CO2 detectors are used to provide detailed cycle-by-cycle analysis. Torque after cold throttle transients is found to be comparable to steady state torque due to allowable spark advance. However, cold transients produce up to 4 times the unburned hydrocarbons when compared to steady state operation. Finally, the x-tau fuel control model is evaluated in this challenging operating regime and is found to provide poor transient fuel control due to excessive fueling.
Characteristic Response of a Production Diesel Oxidation Catalyst Exposed to Lean and Rich PCI Exhaust
Authors: Jacobs Timothy J. , Assanis Dennis N.
Published: March 2009

Although low-temperature premixed compression ignition (PCI) combustion in a light-duty diesel engine offers dramatic and simultaneous reductions in nitric oxides (NOx) and soot, associated increases in unburned hydrocarbons (HC) and carbon monoxide (CO) become unacceptable. Production diesel oxidation catalysts (DOCs) are effective in oxidizing the increased levels of HC and CO under lean combustion conditions. However, the low temperature / high CO combination under rich PCI conditions, designed as a lean NOx trap (LNT) regeneration mode, generally renders the DOC ineffective. The objectives of this study are to characterize the oxidizing efficiency of a production DOC under lean and rich PCI conditions, and attempt to identify probable causes for the observed ineffectiveness under rich PCI. The study uses several tests to characterize the behavior of the DOC under lean PCI and rich PCI combustion conditions, including: (1) steady-state feed gas characterization, (2) transient feed gas characterization, (3) air injection (4) insulated AF sweep, and (5) combustion mode switching. The DOC never becomes effective under rich PCI for any of the tests, suggesting that the platinum-based catalyst may be incorrect for use with rich PCI. Furthermore, combustion mode switching between lean PCI and rich PCI (mimicking LNT loading and regeneration) demonstrates diminishing effectiveness of the DOC during and after continuous mode transitioning.
Low Temperature Combustion Within an HSDI Diesel Engine Using Multiple Injection Strategies
Authors: Fang Tiegang , Coverdill Robert E. , Lee Chia-Fon F. , White Robert A.
Published: March 2009

Low Temperature Compression Ignition (LTCI) combustion employing multiple injection strategies in an optical High-Speed Direct Injection (HSDI) diesel engine was investigated in this work. Heat release characteristics were analyzed through the measurement of in-cylinder pressure. The whole cycle combustion process was visualized with a high-speed digital video camera by imaging natural flame luminosity and three-dimensional-like combustion structures were obtained by taking flame images from both the bottom of the optical piston and the side window simultaneously. The NOx emissions were measured in the exhaust pipe. The effects of pilot injection timing, pilot fuel quantity, main injection timing, operating load, and injection pressure on the combustion and emissions were studied. Low temperature combustion mode was achieved by using a small pilot injection with an injection timing much earlier than TDC followed by a main injection after TDC. For comparison, experiment of a diffusion diesel combustion case was also conducted. Premixed-combustion-dominated heat release rate pattern was seen for all the low temperature combustion cases, while a typical diffusion flame combustion heat release rate was obtained for the conventional combustion case. Highly luminous flame was observed for the conventional combustion condition while much less luminous flame was seen for the low temperature combustion cases. For the higher load and lower injection pressure cases, liquid fuel being injected into low temperature premixed flame was observed for certain cases, which was different from the conventional diesel combustion with liquid fuel injected into hot premixed flame. Compared with the conventional diffusion diesel combustion, simultaneous reduction of soot and NOx was obtained for the low temperature combustion mode at both the same and increased injection pressure with similar operating load. For high load conditions, higher NOx emissions were obtained than the low load conditions with the same injection pressure due to a higher in-cylinder temperature under high load conditions with more fuel burned. However, compared with the diffusion combustion mode with a lower load at lower injection pressure, a significant reduction of soot was achieved for the high load conditions, which shows that increasing injection pressure greatly reduce soot emissions.
Active Air Control System Development Using Charge Air Integrated Manifold Engine Numerical Simulation (CAIMENS)
Authors: Grauer Diana K. , Chapman Kirby S. , Keshavar Ali
Published: March 2009

The natural gas transmission industry integrates turbochargers into the engine system to strategically increase airflow for the purpose of decreasing pollutant emissions, such as Nitrogen Oxide (NOX). Regulations are expected to be tightened in the coming years, forcing transmission companies to look past turbochargers for compliance. The solution to further decreasing emissions lies not in further retrofit, but focusing on the physics of the current system. The flow rate physics of the intake and exhaust manifolds impede equal distribution of air from the turbocharger to each cylinder. Imbalance in airflow creates a discontinuity in the trapped equivalence ratio from cylinder to cylinder. The trapped equivalence ratio is directly proportional to NOX production and a function of the fuel flow rate, airflow rate, and, in two-stroke cycle engines, the scavenging efficiency. Only when these three characteristics are balanced cylinder to cylinder will the combustion and the NOX production in each cylinder be equal. The engine NOX production will be disproportionately high if even one cylinder operates less lean relative to the other cylinders. Balancing the NOX production between cylinders can lower the overall NOX production of the engine. This paper reports on an investigation into the transient, compressible flow physics that impact the trapped equivalence ratio. A comprehensive, variable geometry, multi-cylinder Turbocharger-Reciprocating Engine Computer Simulation (T-RECS) has been developed to illustrate the effect of airflow imbalance on an engine. A new model, the Charge Air Integrated Manifold Engine Numerical Simulation (CAIMENS), is a manifold flow model coupled with the T-RECS engine processor that uses an integrated set of fundamental principles to determine the crank angle-resolved pressure, temperature, burned and unburned mass fractions, and gas exchange rates for the cylinder. CAIMENS has the ability to show the transient impact of one cylinder firing on each successive cylinder. The pulsation model also describes the impact of manifold pressure drop on in-cylinder peak pressure and the pressure wave introduced to the intake manifold by uncovering the intake ports. CAIMENS provides the information necessary to quantify the impact of airflow imbalance, and allows for the visualization of the engine system before and after airflow correction. The model shows that not only does the manifold pressure drop have a significant impact on the in-cylinder peak pressure, but it also has an impact on the pressure wave introduced to the intake manifold as the ports are opened. Also, each cylinder has a considerable impact on the airflow into each successive cylinder.
Thermo-Mechanical Fatigue Life Prediction of a Heavy Duty Diesel Engine Liner
Authors: Malakizadi Amir , Chamani Hamidreza , Shahangian Seyed Navid , Jazayeri Seyed Ali , Sattarifar Iraj
Published: March 2009

Engine designers are increasingly using more advanced simulation techniques to reduce design time and costs and at the same time to improve the accuracy of the work to limit the number of validation tests required. In recent years, the demand for higher specific power has enforced higher operating temperatures in engine parts, so thermo-mechanical fatigue (TMF) analysis is becoming more important. Liners are one of the challenging parts in heavy duty diesel engines which are exposed to high temperature differential between cooling jacket and combustion chamber and also they are in frictional contact with piston rings, therefore liners are subjected to complicated multiaxial thermal and mechanical stresses. In this study, a detailed analysis is conducted on a centrifugal gray cast iron liner using different CAE tools to have a more accurate estimate of thermo-mechanical loads. The coolant flows inside the liner jacket and combustion process within the cylinder are simulated using 3D CFD methods. Besides the linear FE analysis which is known as an oversimplified method, a multilinear kinematic model is used to simulate the material response more accurately. Using experimental results obtained from cylinder liner material, the different TMF approaches have been investigated and the differences between linear and nonlinear FE simulation in lifetime prediction have been revealed. It is shown that modified Manson-Coffin criterion is the promising relation for lifetime prediction of liner material that correlate better with experimental results.
In Vivo Activity of the Pyrrolopyrazolyl-Substituted Oxazolidinone RWJ-416457
Authors: Hilliard Jamese J. , Fernandez Jeffrey , Melton John , Macielag Mark J. , Goldschmidt Raul , Bush Karen , Abbanat Darren
Published: March 2009

RWJ-416457 is an investigational pyrrolopyrazolyl-substituted oxazolidinone with activity against antibiotic-susceptible and -resistant gram-positive pathogens. Efficacies of RWJ-416457, linezolid, and vancomycin against methicillin-susceptibleStaphylococcus aureus(MSSA) and community-associated methicillin-resistantS. aureus(CA-MRSA) in murine skin and systemic infections were compared, as were efficacies againstStreptococcus pneumoniaein a lower respiratory infection. In staphylococcal systemic infections, RWJ-416457 was equipotent with to twofold more potent than linezolid, with 50% effective dose values ranging from 1.5 to 5 mg/kg of body weight/day. RWJ-416457 was two- to fourfold less potent than vancomycin against MSSA but up to fourfold more potent than vancomycin against CA-MRSA. In MSSA and CA-MRSA skin infections, RWJ-416457 demonstrated an efficacy similar to that of linezolid, reducing CFU/g skin approximately 1.0 log10at all doses tested; vancomycin yielded greater reductions than the oxazolidinones, with decreases in CFU/g skin of 3 log10(MSSA) and 2 log10(CA-MRSA). In the pneumococcal model, RWJ-416457 was two- to fourfold more potent than linezolid. The free-drug area under the concentration-time curves at 24 h (fAUC24) were similar for RWJ-416457 and linezolid. The half-life of RWJ-416457 was up to threefold longer than that of linezolid for all routes of administration. ThefAUC24/MIC ratio, the pharmacodynamic parameter considered predictive of oxazolidinone efficacy, was approximately twofold greater for RWJ-416457 than for linezolid. Since thefAUC values were similar for both compounds, the higherfAUC/MIC ratios of RWJ-416457 appear to result from its greater in vitro potency. These results demonstrate that RWJ-416457 is a promising new oxazolidinone with efficacy inS. aureusorS. pneumoniaemouse infection models.
Bactericidal Activity of the Combination of Levofloxacin with Rifampin in Experimental Prosthetic Knee Infection in Rabbits Due to Methicillin-Susceptible
Staphylococcus aureus
Authors: Muller-Serieys Claudette , Saleh Mghir Azzam , Massias Laurent , Fantin Bruno
Published: March 2009

The combination of levofloxacin and rifampin has been recommended for the treatment of staphylococcal prosthetic infection. In a rabbit model of prosthetic knee infection due to a susceptible clinical strain of
Staphylococcus aureus
, the combination of levofloxacin and rifampin was bactericidal, significantly reduced bacterial titers in bone compared with levels for rifampin and controls (
P
< 0.05), sterilized 6 of 12 animals, and prevented the selection of resistant mutants that was observed with rifampin alone, validating clinical recommendations.
In Vivo and In Vitro Patterns of the Activity of Simocyclinone D8, an Angucyclinone Antibiotic from
Streptomyces antibioticus
Authors: Oppegard Lisa M. , Hamann Bree L. , Streck Kathryn R. , Ellis Keith C. , Fiedler Hans-Peter , Khodursky Arkady B. , Hiasa Hiroshi
Published: March 2009

Simocyclinone D8 (SD8) exhibits antibiotic activity against gram-positive bacteria but not against gram-negative bacteria. The molecular basis of the cytotoxicity of SD8 is not fully understood, although SD8 has been shown to inhibit the supercoiling activity of
Escherichia coli
gyrase. To understand the mechanism of SD8, we have employed biochemical assays to directly measure the sensitivities of
E
.
coli
and
Staphylococcus aureus
type II topoisomerases to SD8 and microarray analysis to monitor the cellular responses to SD8 treatment. SD8 is a potent inhibitor of either
E
.
coli
or
S
.
aureus
gyrase. In contrast, SD8 exhibits only a moderate inhibitory effect on
S
.
aureus
topoisomerase IV, and
E
.
coli
topoisomerase IV is virtually insensitive to SD8. The antimicrobial effect of SD8 against
E
.
coli
has become evident in the absence of the AcrB multidrug efflux pump. As expected, SD8 treatment exhibits the signature responses to the loss of supercoiling activity in
E
.
coli
: upregulation of gyrase genes and downregulation of the topoisomerase I gene. Unlike quinolone treatment, however, SD8 treatment does not induce the SOS response. These results suggest that DNA gyrase is the target of SD8 in both gram-positive and gram-negative bacteria and that the lack of the antibacterial effect against gram-negative bacteria is due, in part, to the activity of the AcrB efflux pump.
Relationship of Carbapenem Restriction in 22 University Teaching Hospitals to Carbapenem Use and Carbapenem-Resistant
Pseudomonas aeruginosa
Authors: Pakyz Amy L. , Oinonen Michael , Polk Ronald E.
Published: March 2009

Many hospital antimicrobial stewardship programs restrict the availability of selected drugs by requiring prior approval. Carbapenems may be among the restricted drugs, but it is unclear if hospitals that restrict availability actually use fewer carbapenems than hospitals that do not restrict use. Nor is it clear if restriction is related to resistance. We evaluated the relationship between carbapenem restriction and the volume of carbapenem use and both the incidence rate and proportion of carbapenem-resistant
Pseudomonas aeruginosa
isolates from 2002 through 2006 in a retrospective, longitudinal, multicenter analysis among a consortium of academic health centers. Carbapenem use was measured from billing records as days of therapy per 1,000 patient days. Hospital antibiograms were used to determine both the incidence rate and proportion of carbapenem-resistant
P. aeruginosa
isolates. A survey inquired about restriction policies for antibiotics, including carbapenems. General linear mixed models were used to examine study outcomes. Among 22 hospitals with sufficient data for analysis, overall carbapenem use increased significantly over the 5 years of study (
P
< 0.0001), although overall carbapenem resistance in
P. aeruginosa
did not change. Hospitals that restricted carbapenems (
n
= 8; 36%) used significantly fewer carbapenems (
P
= 0.04) and reported lower incidence rates of carbapenem-resistant
P. aeruginosa
(
P
= 0.01) for all study years. Fluoroquinolone use was a potential confounder of these relationships, but hospitals that restricted carbapenems actually used fewer fluoroquinolones than those that did not. Restriction of carbapenems is associated with both lower use and lower incidence rates of carbapenem resistance in
P. aeruginosa
.
Campylobacter jejuniCocultured with Epithelial Cells Reduces Surface Capsular Polysaccharide Expression
Authors: Corcionivoschi N. , Clyne M. , Lyons A. , Elmi A. , Gundogdu O. , Wren B. W. , Dorrell N. , Karlyshev A. V. , Bourke B.
Published: March 2009

The host cell environment can alter bacterial pathogenicity. We employed a combination of cellular and molecular techniques to study the expression ofCampylobacter jejunipolysaccharides cocultured with HCT-8 epithelial cells. After two passages, the amount of membrane-bound high-molecular-weight polysaccharide was considerably reduced. Microarray profiling confirmed significant downregulation of capsular polysaccharide (CPS) locus genes. Experiments using conditioned media showed that sugar depletion occurred only when the bacterial and epithelial cells were cocultured. CPS depletion occurred whenC. jejuniorganisms were exposed to conditioned media from a differentC. jejunistrain but not when exposed to conditioned media from other bacterial species. Proteinase K or heat treatment of conditioned media under coculture conditions abrogated the effect on the sugars, as did formaldehyde fixation and cycloheximide treatment of host cells or chloramphenicol treatment of the bacteria. However, sugar depletion was not affected in flagellar export (fliQ) and quorum-sensing (luxS) gene mutants. PassagedC. jejunishowed reduced invasiveness and increased serum sensitivity in vitro.C. jejunialters its surface polysaccharides when cocultured with epithelial cells, suggesting the existence of a cross talk mechanism that modulates CPS expression during infection.
Trypanosoma cruziGP63 Proteins Undergo Stage-Specific Differential Posttranslational Modification and Are Important for Host Cell Infection
Authors: Kulkarni Manjusha M. , Olson Cheryl L. , Engman David M. , McGwire Bradford S.
Published: March 2009

The protozoanTrypanosoma cruziexpresses multiple isoforms of the GP63 family of metalloproteases. Polyclonal antiserum against recombinant GP63 ofT. cruzi(TcGP63) was used to study TcGP63 expression and localization in this organism. Western blot analysis revealed that TcGP63 is 61 kDa in epimastigotes, amastigotes, and tissue culture-derived trypomastigotes but 55 kDa in metacyclic trypomastigotes. Antiserum specific forLeishmania amazonensisGP63 specifically reacted with a 55-kDa TcGP63 form in metacyclic trypomastigotes, suggesting stage-specific expression of different isoforms. Surface biotinylation and endoglycosidase digestion experiments showed that TcGP63 is an ecto-glycoprotein in epimastigotes but is intracellular and lacking in N-linked glycans in metacyclic trypomastigotes. Immunofluorescence microscopy showed that TcGP63 is localized on the surfaces of epimastigotes but distributed intracellularly in metacyclic trypomastigotes. TcGP63 is soluble in cold Triton X-100, in contrast toLeishmaniaGP63, which is detergent resistant in this medium, suggesting that GP63 is not raft associated inT. cruzi. Western blot comparison of our antiserum to a previously described anti-peptide TcGP63 antiserum indicates that each antiserum recognizes distinct TcGP63 proteins. Preincubation of trypomastigotes with either TcGP63 antiserum or a purified TcGP63 C-terminal subfragment reduced infection of host myoblasts. These results show that TcGP63 is expressed at all life stages and that individual isoforms play a role in host cell infection.
Vanraj Mini-Tractors: Is Small Beautiful?
Authors: Modi Pratik
Published: March 2009

This case presents the dilemma of the decision maker in selecting the most appropriate market segment for Vanraj 10 HP mini-tractors — an innovation from a small farmer in Gujarat, India. Four market segments were identified: small and marginal farmers, large farmers, industries, and horticulture farmers. Vanraj was economical and possessed all the features of a big tractor. Mr. Trivedi, the decision maker, believed that the tractor would serve the needs of small and marginal farmers better, but his colleagues wanted him to think further before selecting any particular market segment for targeting. This case is useful for exploring segmentation and targeting decisions in marketing.
Superstar Leaders
Authors: Goel Abhishek , Vohra Neharika
Published: March 2009

A common issue in organizations is handling larger than life leaders. These leaders often have "superstar" status in their field and the organization usually gets overwhelmed with their presence. Sometimes, narcissism in them can potentially hurt the organization in the long run. This case highlights a brilliant and charismatic leader in a healthcare institution who unknowingly becomes a bottleneck in the growth of its people and the organization. The case presents qualitative and quantitative data of the leader's and his subordinates' perception of the prevailing culture and leadership practices. Issues on leadership, organizational culture, and people management presented in this case are relevant across industries and organizations.
THERMAL EXPANSION IN SINGLE-WALLED CARBON NANOTUBES AT DIFFERENT TEMPERATURES
Authors: SINGH B. P. , VERMA AMIT
Published: March 2009

Energy stored in a bond depends on the bond length and bond angle. We use computer simulation software to measure the bond lengths and bond angles, diameters and other parameters of single-walled carbon nanotubes (SWCNTs), and employ the results to determine thermal expansion of SWCNTs in the radial and axial directions. It is found in this study that at low temperatures and even at room temperature, SWCNTs show negative thermal expansion in both the radial and axial directions (the diameter and length both decrease with the increase in temperature). At high temperatures the expansion becomes positive in the radial and axial directions (the diameter and length both increase with increasing temperature). Thermal expansion in the radial direction does not depend on the tube helicity. SWCNTs of large diameter show higher thermal expansion in the radial direction than that for small diameter tubes up to 700 K, but beyond 700 K the opposite occurs.
ACOUSTICAL CHARACTERIZATION OF NANOSTRUCTURED METAL
Authors: SINGH R. K. , SINGH R. P. , SINGH M. P.
Published: March 2009

Ultrasonic attenuation due to phonon–phonon interaction, thermoelastic loss and dislocation damping arising from screw and edge dislocations has been evaluated in nanocrystalline copper (13 nm) in the temperature range 50–500 K, and size-dependent attenuation at a constant temperature for longitudinal and shear modes of propagation. Second and third order elastic constants have been obtained, taking the nearest neighbor distance and the hardness parameter as input data. SOEC and TOEC (obtained at different temperatures) have been used to obtain Grüneisen parameters and nonlinearity parameters, which in turn have been used to evaluate α/f2 for longitudinal and shear waves. Results have been discussed, and compared with available experimental values. It has been found that α/f2 increases with temperature and a significant contribution to the total attenuation occurs due to scattering from grain boundaries, and ultrasonic attenuation due to thermoelastic loss is negligible compared to phonon–phonon interaction, establishing that the major part of energy from the sound wave is removed owing to the interaction of acoustic phonons with thermal phonons (lattice vibrations).
Architectural implications of nanoscale integrated sensing and computing
Authors: Pistol Constantin , Chongchitmate Wutichai , Dwyer Christopher , Lebeck Alvin R.
Published: March 2009

This paper explores the architectural implications of integrating computation and molecular probes to form nanoscale sensor processors (nSP). We show how nSPs may enable new computing domains and automate tasks that currently require expert scientific training and costly equipment. This new application domain severely constrains nSP size, which significantly impacts the architectural design space. In this context, we explore nSP architectures and present an nSP design that includes a simple accumulator-based ISA, sensors, limited memory and communication transceivers. To reduce the application memory footprint, we introduce the concept of instruction-fused sensing. We use simulation and analytical models to evaluate nSP designs executing a representative set of target applications. Furthermore, we propose a candidate nSP technology based on optical Resonance Energy Transfer (RET) logic that enables the small size required by the application domain; our smallest design is about the size of the largest known virus. We also show laboratory results that demonstrate initial steps towards a prototype.
Anomaly-based bug prediction, isolation, and validation
Authors: Dimitrov Martin , Zhou Huiyang
Published: March 2009

Software defects, commonly known as bugs, present a serious challenge for system reliability and dependability. Once a program failure is observed, the debugging activities to locate the defects are typically nontrivial and time consuming. In this paper, we propose a novel automated approach to pin-point the root-causes of software failures.

Our proposed approach consists of three steps. The first step is bug prediction, which leverages the existing work on anomaly-based bug detection as exceptional behavior during program execution has been shown to frequently point to the root cause of a software failure. The second step is bug isolation, which eliminates false-positive bug predictions by checking whether the dynamic forward slices of bug predictions lead to the observed program failure. The last step is bug validation, in which the isolated anomalies are validated by dynamically nullifying their effects and observing if the program still fails. The whole bug prediction, isolation and validation process is fully automated and can be implemented with efficient architectural support. Our experiments with 6 programs and 7 bugs, including a real bug in the gcc 2.95.2 compiler, show that our approach is highly effective at isolating only the relevant anomalies. Compared to state-of-art debugging techniques, our proposed approach pinpoints the defect locations more accurately and presents the user with a much smaller code set to analyze.
Complete information flow tracking from the gates up
Authors: Tiwari Mohit , Wassel Hassan M.G. , Mazloom Bita , Mysore Shashidhar , Chong Frederic T. , Sherwood Timothy
Published: March 2009

For many mission-critical tasks, tight guarantees on the flow of information are desirable, for example, when handling important cryptographic keys or sensitive financial data. We present a novel architecture capable of tracking all information flow within the machine, including all explicit data transfers and all implicit flows (those subtly devious flows caused by not performing conditional operations). While the problem is impossible to solve in the general case, we have created a machine that avoids the general-purpose programmability that leads to this impossibility result, yet is still programmable enough to handle a variety of critical operations such as public-key encryption and authentication. Through the application of our novel gate-level information flow tracking method, we show how all flows of information can be precisely tracked. From this foundation, we then describe how a class of architectures can be constructed, from the gates up, to completely capture all information flows and we measure the impact of doing so on the hardware implementation, the ISA, and the programmer.
Commutativity analysis for software parallelization
Authors: Aleen Farhana , Clark Nathan
Published: March 2009

Extracting performance from many-core architectures requires software engineers to create multi-threaded applications, which significantly complicates the already daunting task of software development. One solution to this problem is automatic compile-time parallelization, which can ease the burden on software developers in many situations. Clearly, automatic parallelization in its present form is not suitable for many application domains and new compiler analyses are needed address its shortcomings.

In this paper, we present one such analysis: a new approach for detecting commutative functions. Commutative functions are sections of code that can be executed in any order without affecting the outcome of the application, e.g., inserting elements into a set. Previous research on this topic had one significant limitation, in that the results of a commutative functions must produce identical memory layouts. This prevented previous techniques from detecting functions like malloc, which may return different pointers depending on the order in which it is called, but these differing results do not affect the overall output of the application. Our new commutativity analysis correctly identify these situations to better facilitate automatic parallelization. We demonstrate that this analysis can automatically extract significant amounts of parallelism from many applications, and where it is ineffective it can provide software developers a useful list of functions that may be commutative provided semantic program changes that are not automatable.
TwinDrivers
Authors: Menon Aravind , Schubert Simon , Zwaenepoel Willy
Published: March 2009

In a virtualized environment, device drivers are often run inside a virtual machine (VM) rather than in the hypervisor, for reasons of safety and reduction in software engineering effort. Unfortunately, this approach results in poor performance for I/O-intensive devices such as network cards. The alternative approach of running device drivers directly in the hypervisor yields better performance, but results in the loss of safety guarantees for the hypervisor and incurs additional software engineering costs.

In this paper we present TwinDrivers, a framework which allows us to semi-automatically create safe and efficient hypervisor drivers from guest OS drivers. The hypervisor driver runs directly in the hypervisor, but its data resides completely in the driver VM address space. A Software Virtual Memory mechanism allows the driver to access its VM data efficiently from the hypervisor running in any guest context, and also protects the hypervisor from invalid memory accesses from the driver. An upcall mechanism allows the hypervisor to largely reuse the driver support infrastructure present in the VM. The TwinDriver system thus combines most of the performance benefits of hypervisor-based driver approaches with the safety and software engineering benefits of VM-based driver approaches.

Using the TwinDrivers hypervisor driver, we are able to improve the guest domain networking throughput in Xen by a factor of 2.4 for transmit workloads, and 2.1 for receive workloads, both in CPU-scaled units, and achieve close to 64-67 of native Linux throughput.
Phantom-BTB
Authors: Burcea Ioana , Moshovos Andreas
Published: March 2009

Modern processors use branch target buffers (BTBs) to predict the target address of branches such that they can fetch ahead in the instruction stream increasing concurrency and performance. Ideally, BTBs would be sufficiently large to capture the entire working set of the application and sufficiently small for fast access and practical on-chip dedicated storage. Depending on the application, these requirements are at odds.

This work introduces a BTB design that accommodates large instruction footprints without dedicating expensive onchip resources. In the proposed Phantom-BTB (PBTB) design, a conventional BTB is augmented with a virtual table that collects branch target information as the application runs. The virtual table does not have fixed dedicated storage. Instead, it is transparently allocated, on demand, in the on-chip caches, at cache line granularity. The entries in the virtual table are proactively prefetched and installed in the dedicated conventional BTB, thus, increasing its perceived capacity. Experimental results with commercial workloads under full-system simulation demonstrate that PBTB improves IPC performance over a 1K-entry BTB by 6.9% on average and up to 12.7%, with a storage overhead of only 8%. Overall, the virtualized design performs within 1% of a conventional 4K-entry, single-cycle access BTB, while the dedicated storage is 3.6 times smaller.
A side-loading hermetic sample holder for X-ray powder diffraction
Authors: Reibenspies Joseph H. , Bhuvanesh Nattamai
Published: March 2009

This manuscript describes the construction, testing, and use of a simple side-loading air-tight specimen holder for use with Bruker X-ray powder diffractometers.
X-ray powder diffraction data for high-temperature Al4Re(Ni)
Authors: Grushko B.
Published: March 2009

A monoclinic phase isostructural to Al4W was revealed in Al–Ni–Re close to the Al–Re terminal. It is assumed to be a ternary extension of the high-temperature Al4Re phase usually transforming in binary alloys even by sharp quenching from the existence temperatures. The powder X-ray diffraction pattern of this phase of the Al77Ni2.5Re20.5 composition was indexed for the Cm space group with a=5.1538(12) Å, b=17.410(5) Å, c=5.1546(15) Å, and β=100.548(16)°.
X-ray powder diffraction data for alaptide, 8(S)-methyl-6,9-diazaspiro/4,5/decane-7,10-dione or cyclo(L-Alanyl-1-ami-no-1-cyclopentan carbonyl), cyclo(L-Ala-Acp)
Authors: Maixner J. , Rohlíček J. , Kratochvíl B. , Šturc A.
Published: March 2009

X-ray powder diffraction data, unit cell parameters, and space group for alaptide are presented (a=21.136(4) Å, b=7.212(4) Å, c=6.126(3) Å, space group P212121, cell volume=933.8(8) Å3, and Z=4). All measured lines were indexed and are consistent with the P212121 space group. No detectable impurities were observed.
Panic Disorder: Is the PAG Involved?
Authors: Del-Ben Cristina Marta , Graeff Frederico Guilherme
Published: March 2009

Data from studies with humans have suggested that abnormalities of midbrain structures, including the periaqueductal gray matter (PAG), could be involved in the neurobiology of panic disorder (PD). The electrical stimulation of the PAG in neurosurgical patients induces panic-like symptoms and the effect of drugs that are effective in the treatment of PD in the simulation of public speaking model of anxiety is in agreement with data from animal models of PD. Structural neuroimaging studies have shown increases in gray matter volume of midbrain and pons of PD patients. There is also evidence of lower serotonin transporter and receptor binding, and increases of metabolism in the midbrain of PD patients. Nevertheless, these midbrain abnormalities can not be considered as specific findings, since neuroimaging data indicate that PD patients have abnormalities in other brain structures that process fear and anxiety.
Characterization of Arterial Wave Reflection in Healthy Bonnet Macaques: Feasibility of Applanation Tonometry
Authors: Lazar Jason , Qureshi Ghazanfar , Kamran Haroon , Rosenblum Leonard A. , Kral John G. , Salciccioli Louis
Published: March 2009

Nonhuman primates are commonly used in cardiovascular research. Increased arterial stiffness is a marker of subclinical atherosclerosis and higher CV risk. We determined the augmentation index (AI) using applanation tonometry in 61 healthy monkeys (59% female, age 1–25 years). Technically adequate studies were obtained in all subjects and required1.5±1.3minutes. The brachial artery provided the highest yield (95%). AI was correlated with heart rate (HR) (r=−0.65, P<.001), crown rump length (CRL) (r= 0.42,P= .001), and left ventricular (LV) mass determined using echocardiography (r=0.52, P<.001). On multivariate analysis, HR (P<.001) and CRL (P= .005) were independent predictors of AI (R2=0.46, P<.001). Body Mass Index (BMI) and AI were independent predictors of higher LV mass on multivariate analysis (P<.001andP=.03). In conclusion, applanation tonometry is feasible for determining AI. Reference values are provided for AI in bonnet macaques, in whom higher AI is related to HR and CRL, and in turn contributes to higher LV mass.
Cloning-free regulated monitoring of reporter and gene expression
Authors: al-Haj Latifa , Al-Ahmadi Wijdan , Al-Saif Maher , Demirkaya Omer , Khabar Khalid SA
Published: March 2009

Background

The majority of the promoters, their regulatory elements, and their variations in the human genome remain unknown. Reporter gene technology for transcriptional activity is a widely used tool for the study of promoter structure, gene regulation, and signaling pathways. Construction of transcriptional reporter vectors, including use of cis-acting sequences, requires cloning and time-demanding manipulations, particularly with introduced mutations.

Results

In this report, we describe a cloning-free strategy to generate transcriptionally-controllable linear reporter constructs. This approach was applied in common transcriptional models of inflammatory response and the interferon system. In addition, it was used to delineate minimal transcriptional activity of selected ribosomal protein promoters. The approach was tested for conversion of genes into TetO-inducible/repressible expression cassettes.

Conclusion

The simple introduction and tuning of any transcriptional control in the linear DNA product renders promoter activation and regulated gene studies simple and versatile.
Operating theatre related syncope in medical students: a cross sectional study
Authors: Jamjoom AAB , Nikkar-Esfahani A , Fitzgerald JEF
Published: March 2009

Background

Observing surgical procedures is a beneficial educational experience for medical students during their surgical placements. Anecdotal evidence suggests that operating theatre related syncope may have detrimental effects on students' views of this. Our study examines the frequency and causes of such syncope, together with effects on career intentions, and practical steps to avoid its occurrence.

Methods

All penultimate and final year students at a large UK medical school were surveyed using the University IT system supplemented by personal approach. A 20-item anonymous questionnaire was distributed and results were analysed using the Statistical Package for Social Sciences, version 15.0 (Chicago, Illinois, USA).

Results

Of the 630 clinical students surveyed, 77 responded with details of at least one near or actual operating theatre syncope (12%). A statistically significant gender difference existed for syncopal/near-syncopal episodes (male 12%; female 88%), p < 0.05. Twenty-two percent of those affected were graduate entry medical course students with the remaining 78% undergraduate. Mean age was 23-years (range 20 – 45). Of the 77 reactors, 44 (57%) reported an intention to pursue a surgical career. Of this group, 7 (9%) reported being discouraged by syncopal episodes in the operating theatre. The most prevalent contributory factors were reported as hot temperature (n = 61, 79%), prolonged standing (n = 56, 73%), wearing a surgical mask (n = 36, 47%) and the smell of diathermy (n = 18, 23%). The most frequently reported measures that students found helpful in reducing the occurrence of syncopal episodes were eating and drinking prior to attending theatre (n = 47, 61%), and moving their legs whilst standing (n = 14, 18%).

Conclusion

Our study shows that operating theatre related syncope among medical students is common, and we establish useful risk factors and practical steps that have been used to prevent its occurrence. Our study also highlights the detrimental effect of this on the career intentions of medical students interested in surgery. Based on these findings, we recommend that dedicated time should be set aside in surgical teaching to address this issue prior to students attending the operating theatre.
δ-Catenin promotes prostate cancer cell growth and progression by altering cell cycle and survival gene profiles
Authors: Zeng Yan , Abdallah Agustin , Lu Jian-Ping , Wang Tao , Chen Yan-Hua , Terrian David M , Kim Kwonseop , Lu Qun
Published: March 2009

Background

δ-Catenin is a unique member of β-catenin/armadillo domain superfamily proteins and its primary expression is restricted to the brain. However, δ-catenin is upregulated in human prostatic adenocarcinomas, although the effects of δ-catenin overexpression in prostate cancer are unclear. We hypothesized that δ-catenin plays a direct role in prostate cancer progression by altering gene profiles of cell cycle regulation and cell survival.

Results

We employed gene transfection and small interfering RNA to demonstrate that increased δ-catenin expression promoted, whereas its knockdown suppressed prostate cancer cell viability. δ-Catenin promoted prostate cancer cell colony formation in soft agar as well as tumor xenograft growth in nude mice. Deletion of either the amino-terminal or carboxyl-terminal sequences outside the armadillo domains abolished the tumor promoting effects of δ-catenin. Quantitative RT2 Profiler™ PCR Arrays demonstrated gene alterations involved in cell cycle and survival regulation. δ-Catenin overexpression upregulated cyclin D1 and cdc34, increased phosphorylated histone-H3, and promoted the entry of mitosis. In addition, δ-catenin overexpression resulted in increased expression of cell survival genes Bcl-2 and survivin while reducing the cell cycle inhibitor p21Cip1.

Conclusion

Taken together, our studies suggest that at least one consequence of an increased expression of δ-catenin in human prostate cancer is the alteration of cell cycle and survival gene profiles, thereby promoting tumor progression.
Factor structure and internal consistency of the 12-item General Health Questionnaire (GHQ-12) and the Subjective Vitality Scale (VS), and the relationship between them: a study from France
Authors: Salama-Younes Mareï , Montazeri Ali , Ismaïl Amany , Roncin Charles
Published: March 2009

Background

The objectives of this study were to test the factor structure and internal consistency of the 12-item General Health Questionnaire (GHQ-12) and the Subjective Vitality Scale (VS) in elderly French people, and to test the relationship between these two questionnaires.

Methods

Using a standard 'forward-backward' translation procedure, the English language versions of the two instruments (i.e. the 12-item General Health Questionnaire and the Subjective Vitality Scale) were translated into French. A sample of adults aged 58–72 years then completed both questionnaires. Internal consistency was assessed by Cronbach's alpha coefficient. The factor structures of the two instruments were extracted by confirmatory factor analysis (CFA). Finally, the relationship between the two instruments was assessed by correlation analysis.

Results

In all, 217 elderly adults participated in the study. The mean age of the respondents was 61.7 (SD = 6.2) years. The mean GHQ-12 score was 17.4 (SD = 8.0), and analysis showed satisfactory internal consistency (Cronbach's alpha coefficient = 0.78). The mean VS score was 22.4 (SD = 7.4) and its internal consistency was found to be good (Cronbach's alpha coefficient = 0.83). While CFA showed that the VS was uni-dimensional, analysis for the GHQ-12 demonstrated a good fit not only to the two-factor model (positive vs. negative items) but also to a three-factor model. As expected, there was a strong and significant negative correlation between the GHQ-12 and the VS (r = -0.71, P < 0.001).

Conclusion

The results showed that the French versions of the 12-item General Health Questionnaire (GHQ-12) and the Subjective Vitality Scale (VS) are reliable measures of psychological distress and vitality. They also confirm a significant negative correlation between these two instruments, lending support to their convergent validity in an elderly French population. The findings indicate that both measures have good structural characteristics.