bluuebunny/crossref_metadata_2025 huggingface dataset:
An Optically-Accessible Combustion Apparatus for Direct-Injection Natural Gas Ignition Studies
Authors: Fabbroni Mark A. , Cheng Stewart Xu , Abate Vito , Wallace James S.
Published: March 2009

Research investigating direct injection natural gas (DING) diesel engines shows many attractions in engine performance including higher thermal efficiency and higher power output as well as significant improvement of exhaust emissions. However, ignition of injected natural gas is difficult and requires some form of ignition assist, such as a diesel pilot or a glow plug. This paper introduces the experimental apparatus used for compression ignition engine studies in the Engine Research and Development Laboratory (ERDL) at University of Toronto. The apparatus consists of an optically accessible constant volume combustion bomb coupled to a single-cylinder Cooperative Fuel Research (CFR) engine through its spark plug port. The engine provides rapid compression to create realistic engine conditions in the combustion bomb and also scavenges the combustion products. During the engine compression process, the piston pushes the air from the engine cylinder to the constant volume combustion bomb, generating high-pressure, high-temperature initial conditions and a strong swirling air flow in the constant volume combustion bomb. Experiments were conducted to measure temperatures and pressures in the constant volume combustion bomb for a range of initial conditions. The experiments were complemented by numerically modeling the whole domain of the CFR engine cylinder, the constant volume combustion bomb, and the port connecting them using a modified KIVA-3V code. The code computes spatially and temporally resolved pressure, temperature and swirl intensity in the constant volume combustion bomb during the compression process. The experimental and the numerical results are in satisfactory agreement and provide validation of the initial conditions in the constant volume combustion bomb for subsequent studies of injection and ignition.
In-Use Heavy-Duty Diesel Emissions Measurement Using an Air-to-Fuel Ratio Derived Exhaust Flow Rate
Authors: Nuszkowski John , Bolyard Jason D. , Thompson Gregory J. , Carder Daniel K.
Published: March 2009

Emissions produced by internal combustion engines during laboratory testing have been shown to not fully represent real world applications. Raw emissions measurements have aided the study of vehicle emissions resulting from in-use applications. In-use emissions measurements may be cumbersome; being that direct measurement of exhaust flow rate will often require that the vehicle exhaust system be modified. This paper investigated the feasibility of substituting exhaust air-to-fuel ratio and ECU fuel flow rates for the inferred measurement of exhaust flow rates. The air-to-fuel ratio for a diesel application was solved from the measured raw emissions of CO2, O2, and NOx. A 2002 Ford F-650, powered by a 2002 Cummins ISB diesel engine, was fitted with an Annubar™ exhaust flow rate measurement system (averaging pitot tube) in order to directly measure continuous exhaust flow rates. Concurrently, exhaust flow rates were estimated from air-to-fuel ratio, while “theoretical” exhaust flow rates were derived from engine speed, intake air density, and assumed volumetric efficiency. These surrogate measurements of exhaust flow rates were then compared with the direct measurements of flow rates obtained by the Annubar™ system. Fuel consumption estimates based on the air-to-fuel ratio derived exhaust flow rate and CO2, theoretical exhaust flow rate and CO2, and measured exhaust flow rates and CO2 were then compared with reported ECU fueling rates over the entire test and during NTE events. An error analysis was performed on the air-to-fuel ratio exhaust flow rate equation to quantify uncertainty resulting from the measurements and assumed parameters. The results showed that the air-to-fuel ratio derived exhaust flow rates compared well with the measured exhaust flow rates and the theoretical exhaust flow rates with an R2 value of 0.982 and 0.986, respectively. During highly transient events and motoring conditions, the air-to-fuel ratio derived exhaust flow rates were inaccurate due to analyzer response and zero fueling conditions, respectively. However, during steadier operation, the air-to-fuel ratio derived exhaust flow rate compared to the measured exhaust flow rate and the theoretical exhaust flow rate within 3.5% and 1.9%, respectively. Overall measurement uncertainty was most affected by the CO2 analyzer at high AFRs. The resulting fuel consumptions from AFR derived exhaust flow rate, theoretical exhaust flow rate, and MEMS exhaust flow rate compared to within 2% of each other. The ECU fuel consumption was 5–7% higher than the MEMS, AFR derived, and theoretical.
Increasing Turbocharged Engine Operating Ranges Through Use of a Booster System
Authors: Chapman Kirby S. , Keshavar Ali , Wolfram Kyle
Published: March 2009

In the natural gas industry a large portion of the engines used for compression are lean-burn engines. When these engines operate at low equivalence ratios, oxides of nitrogen (NOX) can be minimized. The lean-burn engines are turbocharged to deliver high air flow to the engine. However, varying ambient temperatures alter the mass flow rate of air delivered to the engine, changing the equivalence ratio the engine fires at. This may cause an engine to be de-rated, or taken off line reducing the gas throughput. This problem can be partially offset by the installation of a turbocharger booster system to increase the available energy at the turbocharger turbine inlet. One method to boost the energy available to drive the turbocharger is to increase the temperature of the exhaust before it enters the turbine via a relatively small dry low NOX burner. A turbocharger booster system was designed, prototyped, installed, and tested at the National Gas Machinery Laboratory (NGML) turbocharger test and research facility (TTRF). The test data show that the addition of a turbocharger booster system increased the speed of the turbocharger without increasing the emission levels. The increase in speed translates to an increased pressure ratio and mass flow rate of air produced by the compressor. By controlling the booster system, constant air flow rate can be achieved regardless of ambient conditions. This paper provides test results that show how the system can be used to increase an engine’s operating range and mitigate ambient effects.
VanB-Type
Enterococcus faecium
Clinical Isolate Successively Inducibly Resistant to, Dependent on, and Constitutively Resistant to Vancomycin
Authors: San Millan Alvaro , Depardieu Florence , Godreuil Sylvain , Courvalin Patrice
Published: March 2009

Three
Enterococcus faecium
strains isolated successively from the same patient, vancomycin-resistant strain BM4659, vancomycin-dependent strain BM4660, and vancomycin-revertant strain BM4661, were indistinguishable by pulsed-field gel electrophoresis and harbored plasmid pIP846, which confers VanB-type resistance. The vancomycin dependence of strain BM4660 was due to mutation P
175
L, which suppressed the activity of the host Ddl
d
-Ala:
d
-Ala ligase. Reversion to resistance in strain BM4661 was due to a G-to-C transversion in the transcription terminator of the

vanRS
B

operon that lowered the free energy of pairing from −13.08 to −6.65 kcal/mol, leading to low-level constitutive expression of the resistance genes from the

P
RB

promoter, as indicated by analysis of peptidoglycan precursors and of VanX
B
d
,
d
-dipeptidase activity. Transcription of the resistance genes, studied by Northern hybridization and reverse transcription, initiated from the

P
YB

resistance promoter, was inducible in strains BM4659 and BM4660, whereas it started from the

P
RB

regulatory promoter in strain BM4661, where it was superinducible. Strain BM4661 provides the first example of reversion to vancomycin resistance of a VanB-type dependent strain not due to a compensatory mutation in the
ddl
or

vanS
B

gene. Instead, a mutation in the transcription terminator of the regulatory genes resulted in transcriptional readthrough of the resistance genes from the

P
RB

promoter in the absence of vancomycin.
Effects of Double Combinations of Amantadine, Oseltamivir, and Ribavirin on Influenza A (H5N1) Virus Infections in Cell Culture and in Mice
Authors: Smee Donald F. , Hurst Brett L. , Wong Min-Hui , Bailey Kevin W. , Morrey John D.
Published: March 2009

An amantadine-resistant influenza A/Duck/MN/1525/81 (H5N1) virus was developed from the low-pathogenic North American wild-type (amantadine-sensitive) virus for studying treatment of infections in cell culture and in mice. Double combinations of amantadine, oseltamivir (or the cell culture-active form, oseltamivir carboxylate), and ribavirin were used. Amantadine-oseltamivir carboxylate and amantadine-ribavirin combinations showed synergistic interactions over a range of doses against wild-type virus in Madin-Darby canine kidney (MDCK) cell culture, but oseltamivir carboxylate-ribavirin combinations did not. Primarily additive interactions were seen with oseltamivir carboxylate-ribavirin combinations against amantadine-resistant virus. The presence of amantadine in drug combinations against the resistant virus did not improve activity. The wild-type and amantadine-resistant viruses were lethal to mice by intranasal instillation. The resistant virus infection could not be treated with amantadine up to 100 mg/kg body weight/day, whereas the wild-type virus infection was treatable with oral doses of 10 (weakly effective) to 100 mg/kg/day administered twice a day for 5 days starting 4 h prior to virus exposure. Drug combination studies showed that treatment of the amantadine-resistant virus infection with amantadine-oseltamivir or amantadine-ribavirin combinations was not significantly better than using oseltamivir or ribavirin alone. In contrast, the oseltamivir-ribavirin (25- and 75-mg/kg/day combination) treatments produced significant reductions in mortality. The wild-type virus infection was markedly reduced in severity by all three combinations (amantadine, 10 mg/kg/day combined with the other compounds at 20 or 40 mg/kg/day) compared to monotherapy with the three compounds. Results indicate a lack of benefit of amantadine in combinations against amantadine-resistant virus, but positive benefits in combinations against amantadine-sensitive virus.
Novel Mechanism for Nisin Resistance via Proteolytic Degradation of Nisin by the Nisin Resistance Protein NSR
Authors: Sun Zhizeng , Zhong Jin , Liang Xiaobo , Liu Jiale , Chen Xiuzhu , Huan Liandong
Published: March 2009

Nisin is a 34-residue antibacterial peptide produced by
Lactococcus lactis
that is active against a wide range of gram-positive bacteria. In non-nisin-producing
L. lactis
, nisin resistance could be conferred by a specific nisin resistance gene (
nsr
), which encodes a 35-kDa nisin resistance protein (NSR). However, the mechanism underlying NSR-mediated nisin resistance is poorly understood. Here we demonstrated that the protein without the predicted N-terminal signal peptide sequence, i.e., NSRSD, could proteolytically inactivate nisin in vitro by removing six amino acids from the carboxyl “tail” of nisin. The truncated nisin (nisin
1-28
) displayed a markedly reduced affinity for the cell membrane and showed significantly diminished pore-forming potency in the membrane. A 100-fold reduction of bactericidal activity was detected for nisin
1-28
in comparison to that for the intact nisin. In vivo analysis indicated that NSR localized on the cell membrane and endowed host strains with nisin resistance by degrading nisin as NSRSD did in vitro, whereas NSRSD failed to confer resistance upon the host strain. In conclusion, we showed that NSR is a nisin-degrading protease. This NSR-mediated proteolytic cleavage represents a novel mechanism for nisin resistance in non-nisin-producing
L. lactis
.
Temporal Trends of Antimicrobial Resistance and Clonality of Invasive
Streptococcus pneumoniae
Isolates in Finland, 2002 to 2006
Authors: Siira Lotta , Rantala Merja , Jalava Jari , Hakanen Antti J. , Huovinen Pentti , Kaijalainen Tarja , Lyytikäinen Outi , Virolainen Anni
Published: March 2009

The antimicrobial resistance of
Streptococcus pneumoniae
, or pneumococcus, is a growing global problem. In our study, 3,571 invasive pneumococcal isolates, recovered from blood and cerebrospinal fluid samples from patients in Finland between the years 2002 and 2006, showed an increase in erythromycin nonsusceptibility from 16% to 28% (
P
< 0.0001) over the 5-year study period, as well as a doubling of penicillin nonsusceptibility from 8% to 16% (
P
< 0.0001). Erythromycin nonsusceptibility increased especially in isolates derived from 0- to 2-year-old children and was 46% for this age group in 2006. Although multiresistance, defined as nonsusceptibility to penicillin, erythromycin, and tetracycline, was fairly rare (5.1% in 2006), 38% of the erythromycin-nonsusceptible isolates were also penicillin nonsusceptible, while 74% of the penicillin-nonsusceptible isolates were nonsusceptible to erythromycin. In contrast to the situation in continental Europe, but mirroring that in North America, the most frequent macrolide resistance determinant carried by 56% of the tested macrolide-resistant pneumococci was the
mef
gene. Serotypes 14, 9V, 19A, 6B, and 19F were most frequently nonsusceptible to erythromycin or penicillin. The penicillin-resistant invasive isolates (
n
= 88) were genotyped by multilocus sequence typing, which revealed the presence of 25 sequence types, 9 of which were novel. The majority of the isolates were related to one of several globally disseminated penicillin- or multiresistant clones, most importantly the
rlrA
adhesion pilus carrying clones Spain
9V
ST156 and Taiwan
19F
ST236. The penicillin-resistant pneumococcal population in Finland is therefore a combination of internationally recognized genotypes as well as novel ones.
Comparative Efficacies of Lipid-Complexed Amphotericin B and Liposomal Amphotericin B against Coccidioidal Meningitis in Rabbits
Authors: Clemons Karl V. , Capilla Javier , Sobel Raymond A. , Martinez Marife , Tong Ann-Jay , Stevens David A.
Published: March 2009

In separate previous studies, we have shown that lipid-complexed amphotericin B (Abelcet [ABLC]) and liposomal amphotericin B (AmBisome [AmBi]) are efficacious against coccidioidal meningitis in rabbits. Here, we compared ABLC and AmBi directly in a coccidioidal meningitis model. Male New Zealand White rabbits were infected with 5 × 10
4
Coccidioides posadasii
arthroconidia by direct cisternal puncture. Therapy with intravenous ABLC or AmBi at 7.5 or 15 mg/kg of body weight or sterile 5% dextrose water (D5W) began 5 days later. Clinical assessments were done daily; cerebrospinal fluid and blood samples were obtained on day 15 and upon euthanasia. Survivors to day 25 were euthanatized, the numbers of CFU in their tissues were determined, and histology analyses of the brains and spinal cords were done. Controls showed progressive disease, whereas animals treated with either dose of either drug showed few clinical signs of infection. All ABLC- or AmBi-treated rabbits survived, whereas eight of nine D5W-treated rabbits were euthanatized before day 25 (
P
< 0.0001). Numbers of CFU in the brains and spinal cords of ABLC- or AmBi-treated animals were 100- to 10,000-fold lower than those in the corresponding tissues of D5W-treated animals (
P
< 0.0006 to 0.0001). However, only two or fewer given a regimen of ABLC or AmBi were cured of infection in both tissues. Fewer ABLC-treated rabbits (four of eight treated with 7.5 mg/kg and five of eight treated with 15 mg/kg) than controls (nine of nine) had meningitis at any level of severity (
P
, 0.015 or 0.043 for animals treated with ABLC at 7.5 or 15 mg/kg, respectively). Although groups of rabbits treated with AmBi regimens did not have significantly fewer animals with meningitis than the control group (
P
> 0.05), ABLC and AmBi were not significantly different. In this model, intravenous ABLC and AmBi were similarly highly effective, with few clinical signs of infection, 100% survival, and significantly reduced fungal burdens among treated animals. There appeared to be little benefit in using the 15-mg/kg dosage of either formulation. There was no significant advantage of one drug over the other for this indication. Further studies are required to determine the lowest effective doses of these formulations.
Novel Plasmid-Encoded Ceftazidime-Hydrolyzing CTX-M-53 Extended-Spectrum β-Lactamase from
Salmonella enterica
Serotypes Westhampton and Senftenberg
Authors: Doublet Benoît , Granier Sophie A. , Robin Frédéric , Bonnet Richard , Fabre Laëtitia , Brisabois Anne , Cloeckaert Axel , Weill François-Xavier
Published: March 2009

We describe the characterization of a novel CTX-M β-lactamase from
Salmonella enterica
. Four
S. enterica
isolates (three of serotype Westhampton and one of serotype Senftenberg) resistant to extended-spectrum cephalosporins (cefotaxime and ceftazidime) were recovered in 2004 from living cockles in three supermarkets located in distant geographic areas in France, which got their supplies from the same fishery. The isolates were found to produce a novel extended-spectrum β-lactamase (ESBL) belonging to the CTX-M-1 phylogenetic group and named CTX-M-53. The CTX-M-53 β-lactamase harbored the substitution Asp240Gly, like the CTX-M-15 enzyme, which is specifically implicated in a higher catalytic efficiency against ceftazidime. The
bla
CTX-M-53
gene was located on a mobilizable 11-kb plasmid, pWES-1. The complete sequence of pWES-1 revealed the presence of a novel insertion sequence, IS
Sen2
, and an IS
26
element upstream and downstream of the
bla
CTX-M-53
gene, respectively; however, transposition assays of the
bla
CTX-M-53
gene were unsuccessful. IS
26
elements may have contributed to the acquisition of the
bla
CTX-M-53
gene. Interestingly, the mobilization module of the pWES-1 plasmid was similar to that of quinolone resistance plasmids (carrying the
qnrS2
gene) from aquatic sources. Although belonging to two serotypes differentiated on the basis of the O-antigen structure (E1 or E4 groups), the isolates were found to be genetically indistinguishable by pulsed-field gel electrophoresis. Multilocus sequence typing showed that the isolates of serotype Westhampton had a sequence type, ST14, common among isolates of serotype Senftenberg. This is the first characterization of the CTX-M-53 ESBL, which represents an additional ceftazidime-hydrolyzing CTX-M enzyme.
GT-1a or GT-1b Subtype-Specific Resistance Profiles for Hepatitis C Virus Inhibitors Telaprevir and HCV-796
Authors: McCown Matthew F. , Rajyaguru Sonal , Kular Simran , Cammack Nick , Nájera Isabel
Published: March 2009

In vitro, telaprevir selects subtype-specific resistance pathways for hepatitis C virus GT-1a and GT-1b, as described to have occurred in patients. In GT-1a, the HCV-796 resistance mutation C316Y has low replication capacity (7%) that can be compensated for by the emergence of the mutation L392F or M414T, resulting in an increase in replication levels of ≥10-fold.
Antimicrobial Susceptibility of
Mycoplasma pneumoniae
Isolates and Molecular Analysis of Macrolide-Resistant Strains from Shanghai, China
Authors: Liu Yang , Ye Xinyu , Zhang Hong , Xu Xiaogang , Li Wanhua , Zhu Demei , Wang Minggui
Published: March 2009

Fifty-three
Mycoplasma pneumoniae
strains were isolated from pediatric patients in Shanghai, China, from October 2005 to February 2008. Of 53 clinical isolates, 44 (83%) were resistant to erythromycin (MICs of >128 μg/ml for all 44 strains), azithromycin, and clarithromycin. All macrolide-resistant
M. pneumoniae
strains harbored an A-to-G transition mutation at position 2063 in 23S rRNA genes. Forty-five (85%) clinical isolates were classified into the P1 gene restriction fragment length polymorphism type I, and six (11%) were type II.
An
Ehrlichia chaffeensis
Tandem Repeat Protein Interacts with Multiple Host Targets Involved in Cell Signaling, Transcriptional Regulation, and Vesicle Trafficking
Authors: Wakeel Abdul , Kuriakose Jeeba A. , McBride Jere W.
Published: March 2009

Ehrlichia chaffeensis
is an obligately intracellular bacterium that exhibits tropism for mononuclear phagocytes forming cytoplasmic membrane-bound microcolonies called morulae. To survive and replicate within phagocytes,
E. chaffeensis
exploits the host cell by modulating a number of host cell processes, but the ehrlichial effector proteins involved are unknown. In this study, we determined that p47, a secreted, differentially expressed, tandem repeat (TR) protein, interacts with multiple host proteins associated with cell signaling, transcriptional regulation, and vesicle trafficking. Yeast two-hybrid analysis revealed that p47 interacts with polycomb group ring finger 5 (PCGF5) protein, Src protein tyrosine kinase FYN (FYN), protein tyrosine phosphatase non-receptor type 2 (PTPN2), and adenylate cyclase-associated protein 1 (CAP1). p47 interaction with these proteins was further confirmed by coimmunoprecipitation assays and colocalization in HeLa cells transfected with p47-green fluorescent fusion protein (AcGFP1-p47). Moreover, confocal microscopy demonstrated p47-expressing dense-cored (DC) ehrlichiae colocalized with PCGF5, FYN, PTPN2, and CAP1. An amino-terminally truncated form of p47 containing TRs interacted only with PCGF5 and not with FYN, PTPN2, and CAP1, indicating differences in p47 domains that are involved in these interactions. These results demonstrate that p47 is involved in a complex network of interactions involving numerous host cell proteins. Furthermore, this study provides a new insight into the molecular and functional distinction of DC ehrlichiae, as well as the effector proteins involved in facilitating ehrlichial survival in mononuclear phagocytes.
Capsule Expression and Genotypic Differences among
Staphylococcus aureus
Isolates from Patients with Chronic or Acute Osteomyelitis
Authors: Lattar Santiago M. , Tuchscherr Lorena P. N. , Caccuri Roberto L. , Centrón Daniela , Becker Karsten , Alonso Claudio A. , Barberis Claudia , Miranda Graciela , Buzzola Fernanda R. , von Eiff Christof , Sordelli Daniel O.
Published: March 2009

There is ample evidence that
Staphylococcus aureus
capsular polysaccharide (CP) promotes virulence. Loss of capsule expression, however, may lead to
S. aureus
persistence in a chronically infected host. This study was conducted to determine the relative prevalence of nonencapsulated
S. aureus
in patients with chronic and acute osteomyelitis. Only 76/118 (64%)
S. aureus
isolates from patients with osteomyelitis expressed CP, whereas all 50 isolates from blood cultures of patients with infections other than osteoarticular infections expressed CP (
P
= 0.0001). A significantly higher prevalence of nonencapsulated
S. aureus
was found in patients with chronic osteomyelitis (53%) than in those with acute osteomyelitis (21%) (
P
= 0.0046).
S. aureus
isolates obtained from multiple specimens from five of six patients with chronic osteomyelitis exhibited phenotypic (expression of CP, α-hemolysin, β-hemolysin, slime, and the small-colony variant phenotype) and/or genotypic (pulsed-field gel electrophoresis and
spa
typing) differences. Nonencapsulated
S. aureus
was recovered from at least one specimen from each chronic osteomyelitis patient. Fourteen isolates obtained from two patients with acute osteomyelitis were indistinguishable from each other within each group, and all produced CP5. In conclusion, we demonstrated that nonencapsulated
S. aureus
is more frequently isolated from patients with chronic osteomyelitis than from those with acute osteomyelitis, suggesting that loss of CP expression may be advantageous to
S. aureus
during chronic infection. Our findings on multiple
S. aureus
isolates from individual patients allow us to suggest that selection of nonencapsulated
S. aureus
is likely to have occurred in the patient during long-term bone infection.
Performance of chest radiograph and CT scan for lung cancer screening in asbestos-exposed workers
Authors: Clin B , Morlais F , Guittet L , Gislard A , Marquignon M-F , Paris C , Caillard J-F , Launoy G , Letourneux M
Published: March 2009

Objectives:

The aim was to compare, in a cohort of asbestos-exposed workers, the sensitivity and the specificity of low-radiation helical chest CT scan with chest radiograph for the biennial screening of bronchopulmonary cancer, according to the size of detected nodules.

Material and methods:

The screening procedure consisted of biennial chest radiograph and monodetector chest CT scan, given to 972 individuals who had been highly exposed to asbestos. A total of 2555 screening procedures were performed. The study focuses on the 1230 screening procedures for which a 2-year follow-up period was available.

Results:

Twenty-four cases of bronchopulmonary cancer were diagnosed. CT scan detected 20 cancers, 12 of which had not been detected by chest radiograph. Sensitivity of chest radiograph and CT scan were, respectively, 33% and 83%, lesions measuring over 2 mm in diameter being considered as suspect. The specificity of chest radiograph and CT scan were, respectively, 95% and 78%.

Calculation of the differential false positive/true positive (FP/TP) ratio and the receiver operating characteristic curve, performed for both chest radiograph and CT scan, facilitated the determination of the best possible compromise between specificity and sensitivity, according to the diameter threshold applied for considering a nodule as suspect.

Conclusions:

Although this study confirms the superior sensitivity of chest CT scan compared with conventional chest radiograph, the associated loss in specificity leads to a recommended diameter of 5 mm as the threshold for considering non-calcified lesions as “suspect”, for the surveillance of asbestos-exposed individuals.
COMPLEXITY RESULTS FOR CR MAPPINGS BETWEEN SPHERES
Authors: D'ANGELO JOHN P. , LEBL JIŘÍ
Published: March 2009

Using elementary number theory, we prove several results about the complexity of CR mappings between spheres. It is known that CR mappings between spheres, invariant under finite groups, lead to sharp bounds for degree estimates on real polynomials constant on a hyperplane. We show here that there are infinitely many degrees for which the uniqueness of sharp examples fails. The proof uses a Pell equation. We then sharpen our results and obtain various congruences guaranteeing nonuniqueness. We also show that a gap phenomenon for proper mappings between balls does not occur beyond a certain target dimension. This proof uses the solution of the postage stamp problem.
NOVEL VOLTAGE-MODE MULTIFUNCTION FILTER USING ONLY TWO DDCCs
Authors: CHEN HUA-PIN , WU KUO-HSIUNG
Published: March 2009

A new voltage-mode biquad with four inputs and four outputs using only two differential difference current conveyors (DDCCs), two grounded capacitors, and two resistors is proposed. The proposed circuit can act as a multifunction voltage-mode filter with one or three inputs and four outputs and can perform simultaneous realization of voltage-mode notch, highpass, bandpass, and lowpass filter signals from the four output terminals, respectively, without any component choice conditions. On the other hand, it also can act as a universal voltage-mode filter with four inputs and a single output and can realize five generic voltage-mode filter signals from the same configuration without any component-matching conditions. Finally, to verify our architecture, we have designed this analog filter chip with TSMC 0.35 μm 2P4M CMOS technology. This chip operates to 1.125 MHz and consumes 30.95 mW. The chip area of the analog filter is about 0.822 mm2.
A ROBUST HIGH-SPEED LOW INPUT IMPEDANCE CMOS CURRENT COMPARATOR
Authors: KASEMSUWAN VARAKORN , KHUCHAROENSIN SURACHET
Published: March 2009

In this paper, a robust high-speed low input impedance CMOS current comparator is proposed. The front end of the comparator uses the modified Wilson current-mirror and diode-connected transistors to perform a current subtraction and current to voltage conversion simultaneously. The circuit is immune to the process variation and has low input impedances. HSPICE is used to verify the circuit performance with a 0.5 μm CMOS technology. The simulation results show the propagation delay of 1.67 ns, input impedances of 123 Ω, and 126 Ω, and average power dissipation of 0.63 mW for ± 0.1 μA input current under the supply voltage of 3 V.
SIMPLIFIED ANALYSIS OF A CYCLOCONVERTER PERIOD
Authors: KATZ INNA , ABRAMOVITZ ALEXANDER
Published: March 2009

This paper presents a simplified analysis of a generalized cycloconverter and suggests a new method for the estimation of the cycloconverter period as a function of the control mode. The paper presents generalized theoretical results supported by computer simulations and demonstrated by examples.
Degussa Stabilizers: Accessing the Chinese Market
Authors: Jenster Per V. , Chen Cissy
Published: March 2009

Degussa, one of the top 10 chemical companies and the largest specialty chemical company in the world, started its operations in China in January 2003. According to one of the key tenets of the Degussa 2008 Program — Make China Happen — the company will significantly need to increase its sales in China by 2008, with focus on Degussa Stabilizers (a division of Degussa which began its operations in China in 2004). In 2005, Degussa Stabilizers held a market share of about 10 percent (in terms of value). Despite positive results, it could not meet the required growth rate and market share projected by the company. Therefore, in order to strengthen its position in the market, the management team of Degussa Stabilizers decided to minimize the production cost and improve customer services. This case challenges students to analyze and evaluate the company's position. Based on the findings from the case study, the students are required to make recommendations that will help Degussa China to adapt to the rapid market changes and increased competition.
Infosys Technologies Limited: The Global Talent Program
Authors: Subramanian Ram , Singh Tripti , Misra Ram , Jayachandran C.
Published: March 2009

Infosys Technologies Limited, the Bangalore-based information technology company, embarked on a global recruitment program in 2006. The first batch of recruits from U.S. universities were brought to the company's Mysore training facility in India and put through a rigorous 16-week training program. By November 2007, the third U.S. batch was on campus for training along with the first batch from the U.K. Each of these batches had around 125 recruits. The company's CEO had charged Infosys' Head of Administration and Human Resources Development, Mohandas Pai, to step up the recruiting to around 1,000 overseas recruits a year from countries such as the US, UK, continental Europe, and China as a way to globalize the workforce.

Pai was concerned that this ambitious recruitment program would strain the company's training function. His concern stemmed from the fact that the trainers had to deal with cultural differences and varied learning styles of overseas recruits. The trainers had done a commendable job of making adjustments while training was ongoing, but Pai wondered if the same adjustments could be made when the scale of recruits increased dramatically. This case is useful for examining the issues of training capacity and cross-cultural training.
RANDOM WALK IN QUASI-PERIODIC RANDOM ENVIRONMENT
Authors: BRÉMONT JULIEN
Published: March 2009

We consider a one-dimensional random walk with finite range in a random medium described by an ergodic translation on a torus. For regular data and under a Diophantine condition on the translation, we prove a central limit theorem with deterministic centering.
OPTICAL AND STRUCTURAL PROPERTIES OF Ag NANOPARTICLES Eu OXIDE FILMS
Authors: DAKHEL A. A.
Published: March 2009

Silver-incorporated europium oxide thin films have been prepared by the successive evaporation method on quartz and silicon substrates. The silver concentration was 2.5% and 8.9% respectively, as measured by X-ray fluorescence. X-ray diffraction revealed that the Eu oxide of these samples remained amorphous after preannealing at 450°C; however, it crystallized in bcc structure at 800°C. The lattice parameter of the crystallized Eu oxide was larger than that of the bulk, due to the adsorption of Ag + ions, which have a higher ionic radius. The optical absorption of the samples manifested the surface plasmon resonance (SPR) phenomenon, which varied with the Ag content and preannealings of the samples at different temperatures. The Ag nanoparticle radius was estimated with the Mie classical theory by using the SPR data analysis.
APPLICATIONS OF A NEW TOPOLOGICAL INDEX EDm IN SOME ALIPHATIC HYDROCARBONS
Authors: NIE CHANGMING , WU YAXIN , WU RONGYAN , JIANG SAIHONG , ZHOU CONGYI
Published: March 2009

A novel index EDm based on ionicity index matrix, improved distance matrix, and branching degree matrix is used to describe the structural information of the molecule and realizes unique characterization of the molecular structures. The quantitative structure–property relationship (QSPR) models, with correlation coefficients (R) in the range of 0.99–1.00 for standard enthalpy of formation ([Formula: see text]), standard entropy ([Formula: see text]), molar volume (V m ), and molar refraction (R m ) of alkanes, alkenes, and alkynes, are subsequently developed using the index EDm. The leave-one-out (LOO) method and random sampling prediction (RSP) method demonstrate the models to be statistically significant and reliable. Compared with other published topological descriptors, the index EDm has many advantages such as zero degeneracy, better simulation, and so on. Furthermore, the models of solubility and octanol–water partition coefficient are built with satisfied results, which further manifests the superiority and wide application of this index.
THE GROWING STRING METHOD FOR FLOWS OF NEWTON TRAJECTORIES BY A SECOND-ORDER METHOD
Authors: QUAPP WOLFGANG
Published: March 2009

The reaction path is an important concept of theoretical chemistry. We use a definition with a reduced gradient (see Quapp et al., Theor Chem Acc100:285, 1998), also named Newton trajectory (NT). To follow a reaction path, we design a numerical scheme for a method for finding a transition state between reactant and product on the potential energy surface: the growing string (GS) method. We extend the method (see W. Quapp, J Chem Phys122:174106, 2005) by a second-order scheme for the corrector step, which includes the use of the Hessian matrix. A dramatic performance enhancement for the exactness to follow the NTs, and a dramatic reduction of the number of corrector steps are to report. Hence, we can calculate flows of NTs. The method works in nonredundant internal coordinates. The corresponding metric to work with is curvilinear. The GS calculation is interfaced with the GamessUS package (we have provided this algorithm on ). Examples for applications are the HCN isomerization pathway and NTs for the isomerization C7ax ↔ C5 of alanine dipeptide.
Kendo
Authors: Olszewski Marek , Ansel Jason , Amarasinghe Saman
Published: March 2009

Although chip-multiprocessors have become the industry standard, developing parallel applications that target them remains a daunting task. Non-determinism, inherent in threaded applications, causes significant challenges for parallel programmers by hindering their ability to create parallel applications with repeatable results. As a consequence, parallel applications are significantly harder to debug, test, and maintain than sequential programs.

This paper introduces Kendo: a new software-only system that provides deterministic multithreading of parallel applications. Kendo enforces a deterministic interleaving of lock acquisitions and specially declared non-protected reads through a novel dynamically load-balanced deterministic scheduling algorithm. The algorithm tracks the progress of each thread using performance counters to construct a deterministic logical time that is used to compute an interleaving of shared data accesses that is both deterministic and provides good load balancing. Kendo can run on today's commodity hardware while incurring only a modest performance cost. Experimental results on the SPLASH-2 applications yield a geometric mean overhead of only 16% when running on 4 processors. This low overhead makes it possible to benefit from Kendo even after an application is deployed. Programmers can start using Kendo today to program parallel applications that are easier to develop, debug, and test.
RapidMRC
Authors: Tam David K. , Azimi Reza , Soares Livio B. , Stumm Michael
Published: March 2009

Miss rate curves (MRCs) are useful in a number of contexts. In our research, online L2 cache MRCs enable us to dynamically identify optimal cache sizes when cache-partitioning a shared-cache multicore processor. Obtaining L2 MRCs has generally been assumed to be expensive when done in software and consequently, their usage for online optimizations has been limited. To address these problems and opportunities, we have developed a low-overhead software technique to obtain L2 MRCs online on current processors, exploiting features available in their performance monitoring units so that no changes to the application source code or binaries are required. Our technique, called RapidMRC, requires a single probing period of roughly 221 million processor cycles (147 ms), and subsequently 124 million cycles (83 ms) to process the data. We demonstrate its accuracy by comparing the obtained MRCs to the actual L2 MRCs of 30 applications taken from SPECcpu2006, SPECcpu2000, and SPECjbb2000. We show that RapidMRC can be applied to sizing cache partitions, helping to achieve performance improvements of up to 27%.
Per-thread cycle accounting in SMT processors
Authors: Eyerman Stijn , Eeckhout Lieven
Published: March 2009

This paper proposes a cycle accounting architecture for Simultaneous Multithreading (SMT) processors that estimates the execution times for each of the threads had they been executed alone, while they are running simultaneously on the SMT processor. This is done by accounting each cycle to either a base, miss event or waiting cycle component during multi-threaded execution. Single-threaded alone execution time is then estimated as the sum of the base and miss event components; the waiting cycle component represents the lost cycle count due to SMT execution. The cycle accounting architecture incurs reasonable hardware cost (around 1KB of storage) and estimates single-threaded performance with average prediction errors around 7.2% for two-program workloads and 11.7% for four-program workloads.

The cycle accounting architecture has several important applications to system software and its interaction with SMT hardware. For one, the estimated single-thread alone execution time provides an accurate picture to system software of the actually consumed processor cycles per thread. The alone execution time instead of the total execution time (timeslice) may make system software scheduling policies more effective. Second, a new class of thread-progress aware SMT fetch policies based on per-thread progress indicators enable system software level priorities to be enforced at the hardware level.
DFTL
Authors: Gupta Aayush , Kim Youngjae , Urgaonkar Bhuvan
Published: March 2009

Recent technological advances in the development of flash-memory based devices have consolidated their leadership position as the preferred storage media in the embedded systems market and opened new vistas for deployment in enterprise-scale storage systems. Unlike hard disks, flash devices are free from any mechanical moving parts, have no seek or rotational delays and consume lower power. However, the internal idiosyncrasies of flash technology make its performance highly dependent on workload characteristics. The poor performance of random writes has been a cause of major concern, which needs to be addressed to better utilize the potential of flash in enterprise-scale environments. We examine one of the important causes of this poor performance: the design of the Flash Translation Layer (FTL), which performs the virtual-to-physical address translations and hides the erase-before-write characteristics of flash. We propose a complete paradigm shift in the design of the core FTL engine from the existing techniques with our Demand-based Flash Translation Layer (DFTL), which selectively caches page-level address mappings. We develop a flash simulation framework called FlashSim. Our experimental evaluation with realistic enterprise-scale workloads endorses the utility of DFTL in enterprise-scale storage systems by demonstrating: (i) improved performance, (ii) reduced garbage collection overhead and (iii) better overload behavior compared to state-of-the-art FTL schemes. For example, a predominantly random-write dominant I/O trace from an OLTP application running at a large financial institution shows a 78% improvement in average response time (due to a 3-fold reduction in operations of the garbage collector), compared to a state-of-the-art FTL scheme. Even for the well-known read-dominant TPC-H benchmark, for which DFTL introduces additional overheads, we improve system response time by 56%.
Crystal structure determination of K2Zn(PO3)4
Authors: Ji L. N. , Chen Y. Q. , Li J. B. , Luo J. , Liang J. K. , Rao G. H.
Published: March 2009

The crystal structure of K2Zn(PO3)4 was determined and refined using the Rietveld method based on the isostructure model of K2Cu(PO3)4. This compound belongs to the monoclinic system with space group Cc and lattice parameters of a=11.0941(2) Å, b=12.5215(3) Å, c=7.6597(2) Å, and β=102.47(2)°. The chemical formula unit per unit cell is Z=4 and the calculated density is 2.938(3) g∕cm3. Zigzag [PO3]∞ chains formed along the a axis, and their period contains eight PO4 tetrahedrons.
Powder diffraction data of Mn2MoO5.0.6H2O
Authors: Arboleda Johana , Echavarría Adriana , Palacio Luz Amparo
Published: March 2009

Manganese molybdate with the formula Mn2MoO5.0.6H2O was synthesized by hydrothermal reaction at 200 °C. The crystal system of this compound is triclinic, space group P−1, Z=1, unit-cell parameters: a=5.7769(5), b=9.7559(6), c=2.8961(2), α=94.37(1), β=101.37(1), and γ=94.75(1). The measured density (Dm) and calculated density (Dx) are 3.200 and 3.103, respectively.
Performance Evaluation of the WSN Routing Protocols Scalability
Authors: Alazzawi L. , Elkateeb A.
Published: March 2009

Scalability is an important factor in designing an efficient routing protocol for wireless sensor networks (WSNs). A good routing protocol has to be scalable and adaptive to the changes in the network topology. Thus scalable protocol should perform well as the network grows larger or as the workload increases. In this paper, routing protocols for wireless sensor networks are simulated and their performances are evaluated to determine their capability for supporting network scalability.
Effect of Educational Level on Oral Health in Peritoneal and Hemodialysis Patients
Authors: Bayraktar Gulsen , Kurtulus Idil , Kazancioglu Rumeyza , Bayramgurler Isil , Cintan Serdar , Bural Canan , Besler Mine , Trablus Sinan , Issever Halim , Aysuna Nilgun , Ozkan Oktay , Yildiz Alaattin
Published: March 2009

Background. In previous studies, the oral and dental health statuses were compared in hemodialysis (HD) and peritoneal dialysis (PD) patients without taking into account the effect of educational levels on oral health. Hence we aimed to make a comparison of these parameters based upon the subjects educational levels.Patients and Methods. 76 PD (33 males, 43 females-mean age:44±12years) and 100 HD (56 males, 44 females-mean age:46±14years) patients were included. The number of decayed, missing and filled teeth were detected, DMFT index was calculated and plaque index (PI) values were assessed.Results. Significantly higher numbers of filled teeth (P<.001) and lower PI values (P<.01) in the PD group were detected with higher educational levels, whereas no significance was detected in the HD group. Higher DMFT index values were assessed in the lower educated and high school levels in PD than HD patients (P<.05). Higher numbers of filled teeth (P<.05) were detected in the secondary school level in PD patients. This difference was even more significant in the high school level (P<.001).Conclusion. We assume that PD patients, who were found to be in a higher educational level, are more caring for their oral health as compared to HD patients.
Chip‐Level HARQ Chase Combining for HSUPA
Authors: Et Tolba Mohamed , Saoudi Samir , Visoz Raphaël , Ait-Idir Tarik
Published: March 2009

Hybrid automatic repeat request (HARQ) is used in high‐speed uplink packet access (HSUPA) to increase the data rate. Chase combining is the simplest of HARQ algorithms. It provides a time diversity and requires a small memory. In this paper, we propose a technique to increase the chase combining efficiency. In this method, HARQ transmissions are seen as additional receive antennas which are jointly combined at chip‐level using a space‐time linear minimum square error (LMMSE). We demonstrate that the chase combining diversity gain is considerably increased especially for high‐order modulation.
Lung Adenocarcinoma Incidence Rates and Their Relation to Motor Vehicle Density
Authors: Chen Fan , Jackson Haley , Bina William F.
Published: March 2009

Background and Objective: The temporal trend of adenocarcinoma incidence rates of the lung (ADL) has been reported to parallel the trend of nitrogen oxide (NOx) emissions in the United States. This study explores the geographic pattern of ADL incidence and its relation to motor vehicle density, the major indicator of NOx emissions before 1970.

Methods: ADL incidence rates by counties were retrieved from the nine sites of Surveillance, Epidemiology, and End Results (SEER) Program for the period of 1973 to 1990. Motor vehicle densities by county in 1970 for these SEER sites were estimated according to the numbers of motor vehicle registration and the size of each county. Regression analysis was done with the data of motor vehicle density by counties.

Results: A dose-response pattern between motor vehicle density and ADL incidence was found. The risks are 136% and 68% higher for ADL and squamous cell carcinoma, respectively, for male residents living in areas with 937 motor vehicles per square mile, compared with those living in areas with about one motor vehicle per square mile. The R2 are as high as 0.805 and 0.504 in regressions for male incidence rates of ADL and squamous cell carcinoma, respectively, with the vehicle density values. As a comparison, the prostate cancer incidence rates did not show dose-response relationship with motor vehicle density. If the effect of NOx emissions on ADL incidence rates can be proved by further studies, the current standard of allowance of NOx emissions may need to be revised. (Cancer Epidemiol Biomarkers Prev 2009;18(3):760–4)