bluuebunny/crossref_metadata_2025 huggingface dataset:
Injury in Organs after Cardiopulmonary Bypass: A Comparative Experimental Morphological Study between a Centrifugal and a New Pulsatile Pump
Authors: Herreros Jesús , Berjano Enrique J. , Sola Josu , Vlaanderen Wouter , Sales‐Nebot Laura , Más Pedro , Padrós Clemente , Díaz Pedro , Rábago Gregorio , Mercé Salvador
Published: July 2004

Abstract:   The aim of this investigation was to assess organ injury provoked by a new pulsatile pump for cardiopulmonary bypass (CPB) with respect to a conventional centrifugal pump. Eight pigs in the pulsatile group (PG) and five in the centrifugal group (CG) underwent a partial CPB lasting 180 min. The animals were sacrificed 180 min after CPB was suspended, and a morphological study of fragments of ventricular wall, liver, lung, and kidney was performed. In CG, centrilobular hepatic necrosis was observed accompanied by sinusoidal dilatation and congestion, multiple focuses of myocardial ischemia, and minor to moderate pulmonary interstitial edema. In PG, diffuse centrilobular sinusoidal congestion in the liver, congestion and capillary dilatation of low intensity in the ventricular wall, and  nonsignificant  pulmonary  interstitial  septal  edema was observed. In the kidney, both groups showed degenerative changes of the tubular cells and nonsignificant tubular dilatation. These  results suggest a better peripheral circulation in the pulsatile group.
New Aspects on the Role of Blood Pressure and Arterial Stiffness in Mechanical Assistance by Intra‐aortic Balloon Pump: In‐vitro Data and Their Application in Clinical Practice
Authors: Papaioannou Theodoros G. , Mathioulakis Dimitrios S. , Stamatelopoulos Kimon S. , Gialafos Elias J. , Lekakis John P. , Nanas John , Stamatelopoulos Stamatios F. , Tsangaris Sokratis G.
Published: July 2004

Abstract:  Despite the well‐known beneficial effects of the intra‐aortic balloon pump (IABP) generally, there are still some clinical conditions accompanied by IABP ineffectiveness. The aim of this study was the investigation of the independent effects of arterial stiffness and blood pressure on acute IABP effectiveness. For this purpose, a mock circulatory system and 20 patients with cardiogenic shock due to acute myocardial infarction, were employed. It was shown that IABP acute efficiency was determined primarily by arterial compliance (AC) rather than blood pressure alone. IABP induced low hemodynamic effects in patients with systolic blood pressure > 80 mm Hg but with increased AC, whereas IABP resulted in greater hemodynamic effectiveness in cases with systolic pressure < 70 mm Hg but lower AC. The present study provides evidence concerning the hemodynamic conditions, which might lead to optimization of IABP or to the prediction of its acute hemodynamic performance, based on both measurements of AC and blood   pressure.
Right Versus Left Internal Jugular Vein Catheterization for Hemodialysis: Complications and Impact on Ipsilateral Access Creation
Authors: Salgado Octavio J. , Urdaneta Bella , Colmenares Berkis , García Rafael , Flores Carmen
Published: July 2004

Abstract:  This study investigated whether the anatomical differences between right and left internal jugular vein catheterization (RJVC and LJVC) would lead to differences in the frequency of complications, in particular, central vein occlusion (CVO). A group of 479 jugular vein catheterizations, 403 RJVC and 77 LJVC done in 294 prevalent hemodialysis patients were analyzed. A right‐sided carotid pseudoaneurysm was the only major puncture‐related complication. A total of 78 RJVC and 17 LJVC were inserted more than once in the same position. Of the RJVC, 44 (10.9%) of 403 were removed because of infection compared with 16 (20.8%) of 77 LJVC (P < 0.02). The overall incidence of infections was 1.58 episodes of infection per 1000 catheter days, 1.57 for RJVC and 3.72 for LJVC, respectively. Catheter dwell times were not different. A group of 127 patients with former RJVC and 44 with LJVC had ipsilateral arteriovenous access (RJVC+ and LJVC+ group, respectively). Four diabetic LJVC+ developed severe arm swelling secondary to CVO leading ultimately to access ligation. The RJVC+ group had no access ligated.  LJVC  may  cause CVO  in diabetics.
Presidential Address, Committing to Commit: Short‐term Debt When Enforcement Is Costly
Authors: Diamond Douglas W.
Published: July 2004

In legal systems with expensive or ineffective contract enforcement, it is difficult to induce lenders to enforce debt contracts. If lenders do not enforce, borrowers will have incentives to misbehave. Lenders have incentives to enforce given bad news when debt is short‐term and subject to runs caused by externalities across lenders. Lenders will not undo these externalities by negotiation. The required number of lenders increases with enforcement costs. A very high enforcement cost can exceed the ex ante incentive benefit of enforcement. Removing lenders' right to immediately enforce their debt with a “bail‐in” can improve the ex ante incentives of borrowers.
Why Do Firms Use Incentives That Have No Incentive Effects?
Authors: Oyer Paul
Published: July 2004

This paper illustrates why firms might choose to implement stock option plans or other pay instruments that reward “luck.” I consider a model where adjusting compensation contracts is costly and where employees' outside opportunities are correlated with their firms' performance. The model may help to explain the use and recent rise of broad‐based stock option plans, as well as other financial instruments, even when these pay plans have no effect on employees' on‐the‐job behavior. The model suggests that agency theory's often‐overlooked participation constraint may be an important determinant of some common compensation schemes, particularly for employees below the highest executive ranks.
The Timing of Option Repricing
Authors: Callaghan Sandra Renfro , Saly P. Jane , Subramaniam Chandra
Published: July 2004

We investigate whether executive stock option repricings are systematically timed to coincide with favorable movements in the company's stock price. For a sample of 236 repricing events, we observe sharp increases in stock price in the 20‐day period following the repricing date. In addition, repricing dates tend to either precede the release of good news or follow the release of bad news in the quarterly earnings announcements. Since information about stock option repricing is not generally released to the public around the repricing date, these findings suggest that CEOs opportunistically manage the timing of the option repricing date.
Estimation and Test of a Simple Model of Intertemporal Capital Asset Pricing
Authors: Brennan Michael J. , Wang Ashley W. , Xia Yihong
Published: July 2004

A simple valuation model with time‐varying investment opportunities is developed and estimated. The model assumes that the investment opportunity set is completely described by the real interest rate and the maximum Sharpe ratio, which follow correlated Ornstein–Uhlenbeck processes. The model parameters and time series of the state variables are estimated using U.S. Treasury bond yields and expected inflation from January 1952 to December 2000, and as predicted, the estimated maximum Sharpe ratio is related to the equity premium. In cross‐sectional asset‐pricing tests, both state variables have significant risk premia, which is consistent with Merton's ICAPM.
The Cash Flow Sensitivity of Cash
Authors: Almeida Heitor , Campello Murillo , Weisbach Michael S.
Published: July 2004

We model a firm's demand for liquidity to develop a new test of the effect of financial constraints on corporate policies. The effect of financial constraints is captured by the firm's propensity to save cash out of cash flows (the cash flow sensitivity of cash). We hypothesize that constrained firms should have a positive cash flow sensitivity of cash, while unconstrained firms' cash savings should not be systematically related to cash flows. We empirically estimate the cash flow sensitivity of cash using a large sample of manufacturing firms over the 1971 to 2000 period and find robust support for our theory.
The Price Response to S&P 500 Index Additions and Deletions: Evidence of Asymmetry and a New Explanation
Authors: Chen Honghui , Noronha Gregory , Singal Vijay
Published: July 2004

We study the price effects of changes to the S&P 500 index and document an asymmetric price response: There is a permanent increase in the price of added firms but no permanent decline for deleted firms. These results are at odds with extant explanations of the effects of index changes that imply a symmetric price response to additions and deletions. A possible explanation for asymmetric price effects arises from the changes in investor awareness. Results from our empirical tests support the thesis that changes in investor awareness contribute to the asymmetric price effects of S&P 500 index additions and deletions.
Ablation Lesion Size Correlates with Pacing Threshold:
Authors: SAPP JOHN L. , SOEJIMA KYOKO , COOPER JOSHUA M. , EPSTEIN LAURENCE M. , STEVENSON WILLIAM G.
Published: July 2004

The virtual electrode model predicts that pacing stimulus strength should reflect proximity of the pacing electrode to excitable myocardium, allowing pacing threshold to assess radiofrequency (RF) ablation lesions and unexcitable scar. The purpose of this study is to correlate RF lesion size with pacing threshold and electrogram (EG) amplitude change at the ablation site. In four swine (32–58 kg, 20 ventricular RF lesions were created using a 4‐mm tip electrode catheters under fluoroscopic and electroanatomic guidance. Unipolar pacing threshold and bipolar and unipolar EG amplitude were measured before and after ablation and compared with lesion size measured in the fixed, serially sectioned tissue. Lesion diameter ranged from 6.4 to 19 mm and volume ranged from 29 to 1920 mm.3 Ablation increased the pacing threshold by 320%, from 0.9 ± 0.3 to 3.6 ± 2.6 mA, P < 0.001. The change in pacing threshold correlated with lesion volume R = 0.88, P < 0.001). Linear regression predicts that lesion volume (mm3) = 160 X rise in pacing threshold + 13. Ablation reduced peak to peak bipolar EG amplitude by 56%, from 2.5 ± 2.0 mV to 1.1 ± 0.6 mV (P = 0.005). Unipolar EG amplitude diminished by only 22% from 4.0 ± 1.6 to 3.2 ± 0.9 mV postablation (P = 0.005). The correlations of lesion volume with change in either bipolar R = 0.14, P = 0.6) or unipolar R = 0.18, P = 0.6) EG amplitude were poor. Pacing threshold correlates with RF ablation lesion size, consistent with the virtual electrode model. In normal myocardium, change in pacing threshold is likely to be a better marker of lesion size than electrogram amplitude. (PACE 2004; 27:933–937)
Is Isolation of All Four Pulmonary Veins Necessary in Patients with Paroxysmal Atrial Fibrillation?
Authors: KATRITSIS DEMOSTHENES G. , ELLENBOGEN KENNETH A.
Published: July 2004

The upper pulmonary veins (PVs) are responsible for the majority of atrial fibrillation (AF) triggering foci, whereas the inferior PVs are more difficult to ablate and prone to postablation ostial stenosis. Most procedure failures can be attributed to incomplete isolation or recurrent PV left atrial reconnection rather than to identification of another focus. Furthermore, in certain patients AF triggers can be detected outside the PVs, and local denervation of the ganglionic plexus around the superior PV left atrial junctions following the ablation procedure may also play a role in eliminating AF. Based on these data, the authors propose that in AF patients the superior PVs should be ablated first, and in case of recurrence a second procedure should be performed for identification of PV left atrial reconnection or extrapulmonary foci and additional ablation of the inferior PVs. Such a staged approach might offer slightly lower success rates but with a significantly lower radiation exposure and procedural time and at a smaller risk of ablation induced PV stenosis. (PACE 2004; 27:938–940)
Comparison of the Specificity of Implantable Dual Chamber Defibrillator Detection Algorithms
Authors: HINTRINGER FLORIAN , DEIBL MARTINA , BERGER THOMAS , PACHINGER OTMAR , ROITHINGER FRANZ XAVER
Published: July 2004

The aim of the study was to compare the specificity of dual chamber ICDs detection algorithms for correct classification of supraventricular tachyarrhythmias derived from clinical studies according to their size to detect an impact of sample size on the specificity. Furthermore, the study sought to compare the specificities of detection algorithms calculated from clinical data with the specificity calculated from simulations of tachyarrhythmias. A survey was conducted of all available sources providing data regarding the specificity of five dual chamber ICDs. The specificity was correlated with the number of patients included, number of episodes, and number of supraventricular tachyarrhythmias recorded. The simulation was performed using tachyarrhythmias recorded in the electrophysiology laboratory. The range of the number of patients included into the studies was 78–1,029, the range of the total number of episodes recorded was 362–5,788, and the range of the number of supraventricular tachyarrhythmias used for calculation of the specificity for correct detection of these arrhythmias was 100 (Biotronik) to 1662 (Medtronic). The specificity for correct detection of supraventricular tachyarrhythmias was 90% (Biotronik), 89% (ELA Medical), 89% (Guidant), 68% (Medtronic), and 76% (St. Jude Medical). There was an inverse correlation (r =−0.9, P = 0.037) between the specificity for correct classification of supraventricular tachyarrhythmias and the number of patients. The specificity for correct detection of supraventricular tachyarrhythmias calculated from the simulation after correction for the clinical prevalence of the simulated tachyarrhythmias was 95% (Biotronik), 99% (ELA Medical), 94% (Guidant), 93% (Medtronic), and 92% (St. Jude Medical). In conclusion, the specificity of ICD detection algorithms calculated from clinical studies or registries may depend on the number of patients studied. Therefore, a direct comparison between different detection algorithms based on clinical data is difficult. In contrast, simulation of supraventricular tachyarrhythmias using a uniform database may be a better tool for direct comparison of the specificity of ICD detection algorithms. (PACE 2004; 27:976–982)
Unexpected Loss of Atrial Tracking Caused by Interaction Between Temporary and Permanent Right Ventricular Leads During Implantation of a Biventricular Pacemaker
Authors: CHANG KUAN‐CHENG , CHEN JAN‐YOW , LIN JEN‐JYH , HUNG JUI‐SUNG
Published: July 2004

This report describes a patient who underwent implantation of an atriobiventricular pacemaker following AV junction ablation and insertion of a temporary right ventricular (RV) pacemaker. During implantation, intermittent loss of sinus P wave tracking occurred when the three permanent leads were connected to the generator. Analysis of marker annotation disclosed intermittent abnormal ventricular sensing that reinitiated postventricular atrial blanking and caused failure of P wave tracking. This phenomenon disappeared after removing the temporary RV lead, but not by turning off the temporary pacemaker. We assume that mechanical contact between the temporary and the permanent RV leads is the underlying mechanism. (PACE 2004; 27:998–1001)
Catecholamine Dependent Accessory Pathway Automaticity
Authors: TSENG ZIAN H. , YADAV ANIL V. , SCHEINMAN MELVIN M.
Published: July 2004

Automaticity from extra nodal accessory pathways appears to be rare. We report the case of a man with the WPW syndrome who presented for repeat electrophysiological study and catheter ablation. After successful ablation of a para‐Hisian accessory pathway, an isoproterenol challenge produced an accelerated wide complex rhythm that was dissociated from sinus rhythm and matched the previous pattern of maximal preexcitation. This automatic rhythm was transient and dependent on catecholamine administration. One month after successful ablation, an exercise treadmill test (ETT) did not demonstrate any pre‐excitation or ectopy. (PACE 2004; 27:1005–1007)
Implantation of a Biventricular Pacing System in a Patient with a Persistent Left Superior Vena Cava
Authors: PAULUSSEN GUIDO M.G. , VAN GELDER BERRY M.
Published: July 2004

The presence of a persistent left superior vena cava was encountered in a 64‐year‐old man undergoing implantation of a biventricular pacing system. Leads with active fixation were positioned in the right atrium and right ventricle, through the persistent left superior vena cava and the proximal segment of the coronary sinus. For left ventricular pacing, a standard bipolar lead was positioned directly in the posterior branch of the coronary sinus without the use of special guiding catheters. (PACE 2004; 27:1014–1016)
Histological examination of pressure ulcer tissue in terminally ill cancer patients
Authors: KITAGAWA Atsuko , SANADA Hiromi , NAKATANI Toshio , SUGAMA Junko , KONYA Chizuko , OKUWA Mayumi , NAGAKAWA Takukazu
Published: July 2004

Aim:  It is a common belief that terminally ill cancer patients have a reduced tissue tolerance that makes them more susceptible than other patients to developing pressure ulcers. However, the actual changes at the tissue level caused by pressure loading in terminally ill cancer patients are unknown, so we examined the relationship between the macroscopic and microscopic features of the tissues of such patients with and without pressure ulcers.

Methods:  The pressure ulcers of four patients were macroscopically evaluated until the time of death, after which informed consent of the family was obtained to examine the underlying skin tissue histologically. Samples were taken from several sites on the abdomen, which does not experience pressure loading, and from the sacral area. Two of the subjects had no observable pressure ulcers and the other two had a stage I and stage II (National Pressure Ulcer Advisory Panel classification) pressure ulcer, respectively. The samples were processed, stained and examined by using light and transmission electron microscopy.

Results:  The non‐pressure ulcer samples showed degenerated keratinocytes, leakage of erythrocytes from the capillaries in the dermal papillae, vascular inflammation, and edema. The samples from the stage I and II ulcers had the additional changes of dilated capillaries and vascular inflammation in and around the wound area.

Conclusion:  Terminally ill cancer patients have damaged skin tissue and inflammation that are not evident by macroscopic examination.
Disaster nursing in a ubiquitous society
Authors: YAMAMOTO Aiko
Published: July 2004

This plan, in order to develop a center of excellence on disaster nursing in a ubiquitous society, focuses on preparing for disasters, the period immediately after disasters, and the mid‐ to long‐term period after disasters. The purpose of this project is to develop self‐care abilities of communities and individuals to independently regenerate and recover from the consequences of disasters. This project consists of three research sections: (i) establishment of an information base; (ii) establishment of nursing support networks; and (iii) development of nursing care strategies. By using questionnaires, interviews and the action research method, the research will be conducted to cover three sections. The six outcomes such as to construct an information liaison system, to develop nursing care strategies, and others will be expected 5 years later.
Large-Scale Copy Number Polymorphism in the Human Genome
Authors: Sebat Jonathan , Lakshmi B. , Troge Jennifer , Alexander Joan , Young Janet , Lundin Pär , Månér Susanne , Massa Hillary , Walker Megan , Chi Maoyen , Navin Nicholas , Lucito Robert , Healy John , Hicks James , Ye Kenny , Reiner Andrew , Gilliam T. Conrad , Trask Barbara , Patterson Nick , Zetterberg Anders , Wigler Michael
Published: July 2004

The extent to which large duplications and deletions contribute to human genetic variation and diversity is unknown. Here, we show that large-scale copy number polymorphisms (CNPs) (about 100 kilobases and greater) contribute substantially to genomic variation between normal humans. Representational oligonucleotide microarray analysis of 20 individuals revealed a total of 221 copy number differences representing 76 unique CNPs. On average, individuals differed by 11 CNPs, and the average length of a CNP interval was 465 kilobases. We observed copy number variation of 70 different genes within CNP intervals, including genes involved in neurological function, regulation of cell growth, regulation of metabolism, and several genes known to be associated with disease.
GRACE Measurements of Mass Variability in the Earth System
Authors: Tapley Byron D. , Bettadpur Srinivas , Ries John C. , Thompson Paul F. , Watkins Michael M.
Published: July 2004

Monthly gravity field estimates made by the twin Gravity Recovery and Climate Experiment (GRACE) satellites have a geoid height accuracy of 2 to 3 millimeters at a spatial resolution as small as 400 kilometers. The annual cycle in the geoid variations, up to 10 millimeters in some regions, peaked predominantly in the spring and fall seasons. Geoid variations observed over South America that can be largely attributed to surface water and groundwater changes show a clear separation between the large Amazon watershed and the smaller watersheds to the north. Such observations will help hydrologists to connect processes at traditional length scales (tens of kilometers or less) to those at regional and global scales.
Controlling the Charge State of Individual Gold Adatoms
Authors: Repp Jascha , Meyer Gerhard , Olsson Fredrik E. , Persson Mats
Published: July 2004

The nature and control of individual metal atoms on insulators are of great importance in emerging atomic-scale technologies. Individual gold atoms on an ultrathin insulating sodium chloride film supported by a copper surface exhibit two different charge states, which are stabilized by the large ionic polarizability of the film. The charge state and associated physical and chemical properties such as diffusion can be controlled by adding or removing a single electron to or from the adatom with a scanning tunneling microscope tip. The simple physical mechanism behind the charge bistability in this case suggests that this is a common phenomenon for adsorbates on polar insulating films.
Antibiotic-Inducible Promoter Regulated by the Cell Envelope Stress-Sensing Two-Component System LiaRS of
Bacillus subtilis
Authors: Mascher Thorsten , Zimmer Sara L. , Smith Terry-Ann , Helmann John D.
Published: July 2004

Soil bacteria are among the most prodigious producers of antibiotics. The
Bacillus subtilis
LiaRS (formerly YvqCE) two-component system is one of several antibiotic-sensing systems that coordinate the genetic response to cell wall-active antibiotics. Upon the addition of vancomycin or bacitracin, LiaRS autoregulates the
liaIHGFSR
operon. We have characterized the promoter of the
lia
operon and defined the
cis
-acting sequences necessary for antibiotic-inducible gene expression. A survey for compounds that act as inducers of the
lia
promoter revealed that it responds strongly to a subset of cell wall-active antibiotics that interfere with the lipid II cycle in the cytoplasmic membrane (bacitracin, nisin, ramoplanin, and vancomycin). Chemicals that perturb the cytoplasmic membrane, such as organic solvents, are also weak inducers. Thus, the reporter derived from P

liaI

(the
liaI
promoter) provides a tool for the detection and classification of antimicrobial compounds.
Doripenem versus
Pseudomonas aeruginosa
In Vitro: Activity against Characterized Isolates, Mutants, and Transconjugants and Resistance Selection Potential
Authors: Mushtaq Shazad , Ge Yigong , Livermore David M.
Published: July 2004

Doripenem is a broad-spectrum parenteral carbapenem under clinical development in Japan and North America. Its activities against (i)
Pseudomonas aeruginosa
isolates with graded levels of intrinsic efflux-type resistance, (ii) mutants with various combinations of AmpC and OprD expression, (iii) PU21 transconjugants with class A and D β-lactamases, and (iv)
P. aeruginosa
isolates with metallo-β-lactamases were tested by the agar dilution method of the National Committee for Clinical Laboratory Standards. Selection of resistant
P. aeruginosa
mutants was investigated in single- and multistep procedures. Doripenem MICs for isolates without acquired resistance mostly were 0.12 to 0.5 μg/ml, whereas meropenem MICs were 0.25 to 0.5 μg/ml and imipenem MICs were 1 to 2 μg/ml. The MICs of doripenem, meropenem, ertapenem, and noncarbapenems for isolates with increased efflux-type resistance were elevated, whereas the MICs of imipenem were less affected. The MICs of doripenem were increased by the loss of OprD but not by derepression of AmpC; nevertheless, and as with other carbapenems, the impermeability-determined resistance caused by the loss of OprD corequired AmpC activity and was lost in OprD
−
mutants also lacking AmpC. The TEM, PSE, PER, and OXA enzymes did not significantly protect
P. aeruginosa
PU21 against the activity of doripenem, whereas MICs of ≥16 μg/ml were seen for clinical isolates with VIM and IMP metallo-β-lactamases. Resistant mutants seemed to be harder to select with doripenem than with other carbapenems (or noncarbapenems), and the fold increases in the MICs were smaller for the resistant mutants. Single-step doripenem mutants were mostly resistant only to carbapenems and had lost OprD; multistep mutants had broader resistance, implying the presence of additional mechanisms, putatively including up-regulated efflux. Most mutants selected with aminoglycosides and quinolones had little or no cross-resistance to carbapenems, including doripenem.
Distribution of Human Immunodeficiency Virus Type 1 Protease and Reverse Transcriptase Mutation Patterns in 4,183 Persons Undergoing Genotypic Resistance Testing
Authors: Rhee Soo-Yon , Liu Tommy , Ravela Jaideep , Gonzales Matthew J. , Shafer Robert W.
Published: July 2004

In a sample of 6,156 sequences from 4,183 persons, the top 30 patterns of protease inhibitor, nucleoside reverse transcriptase (RT) inhibitor, and nonnucleoside RT inhibitor mutations accounted for 55, 46, and 66%, respectively, of sequences with drug resistance mutations. Characterization of the phenotypic and clinical significance of these common patterns may lead to improved treatment recommendations for a large proportion of patients for whom antiretroviral therapy is failing.
A Lipid-Peptide Microbicide Inactivates Herpes Simplex Virus
Authors: Isaacs Charles E. , Jia Jun Hua , Xu Weimin
Published: July 2004

A microbicide combining the lipid-ether 1-0-octyl-sn-glycerol (OG; 3 mM) and peptide D2A21 (9 μM) reduced herpes simplex virus type 1 (HSV-1) and HSV-2 titers by at least 1,000-fold, more than the sum of the inactivations produced by OG and D2A21 alone. OG plus D2A21 reduced HSV-1 and HSV-2 titers by ≥1,000-fold in ≤10 and ≤20 min, respectively, whereas OG and D2A21 used alone produced almost no virus inactivation during these times.
The V Antigen ofPseudomonas aeruginosaIs Required for Assembly of the Functional PopB/PopD Translocation Pore in Host Cell Membranes
Authors: Goure Julien , Pastor Alexandrine , Faudry Eric , Chabert Jacqueline , Dessen Andréa , Attree Ina
Published: July 2004

Pseudomonas aeruginosaefficiently intoxicates eukaryotic cells through the activity of the type III secretion-translocation system (TTSS). Gene deletions within the translocation operonpcrGVH-popBDabolish pore-forming activity ofP. aeruginosastrains with macrophages and TTSS-dependent hemolysis. Here we investigated the requirements for PcrV, PopB, and PopD in pore formation by analyzing specific mutants using red blood cells (RBCs) and fibroblasts expressing green fluorescent protein fused to actin. Simultaneous secretion of three proteins, PopB, PopD, and PcrV, was required to achieve wild-type hemolysis and effector translocation. Deletion ofpcrVin a cytotoxic strain did not affect secretion of PopB and PopD but abolished hemolytic activity and translocation of effectors into fibroblasts. Notably, the PcrV-deficient mutant was not capable of inserting PopD into host cell membranes, whereas PopB and PopD, but not PcrV, were readily found within membranes of wild-type-infected RBCs. Immunoprecipitation experiments performed by using a liposome model of pore assembly revealed a direct interaction between PopD and PopB but not between PopD and PcrV. Consequently, PcrV is necessary for the functional assembly of the PopB/D translocon complex but does not interact directly with pore-forming Pop proteins.
Interaction ofChlamydia trachomatisSerovar L2 with the Host Autophagic Pathway
Authors: Al-Younes Hesham M. , Brinkmann Volker , Meyer Thomas F.
Published: July 2004

Chlamydiae are obligate intracellular pathogens that replicate within a membrane-bound compartment (the inclusion) and are associated with important human diseases, such as trachoma, pneumonia, and atherosclerosis. We have examined the interaction of the host autophagic pathway withChlamydia trachomatisserovar L2 by using the specific autophagosomal stain monodansylcadaverine, antibodies to autophagosome-associated markers, and traditionally used autophagic inhibitors, particularly 3-methyladenine and amino acids. Chlamydial inclusions did not sequester monodansylcadaverine, suggesting absence of fusion with autophagosomes. Interestingly, exposure of cultures infected for 19 h to 3-methyladenine or single amino acids until the end of infection (44 h) caused various degrees of abnormalities in the inclusion maturation and in the progeny infectivity. Incubation of host cells with chemicals throughout the entire period of infection modulated the growth ofChlamydiaeven more dramatically. Remarkably, autophagosomal markers MAP-LC3 and calreticulin were redistributed to the inclusion ofChlamydia, a process that appears to be sensitive to 3-methyladenine and some amino acids. The present data indicate the lack of autophagosomal fusion with the inclusion because it was devoid of monodansylcadaverine and no distinct rim of autophagosomal protein-specific staining around the inclusion could be observed. However, high sensitivity ofChlamydiato conditions that could inhibit host autophagic pathway and the close association of MAP-LC3 and calreticulin with the inclusion membrane still suggest a potential role of host autophagy in the pathogenesis ofChlamydia.
Human Diffusely AdheringEscherichia coliExpressing Afa/Dr Adhesins That Use Human CD55 (Decay-Accelerating Factor) as a Receptor Does Not Bind the Rodent and Pig Analogues of CD55
Authors: Hudault Sylvie , Spiller O. Brad , Morgan B. Paul , Servin Alain L.
Published: July 2004

Afa/Dr diffusely adheringEscherichia coli(DAEC) bacteria that are responsible for recurrent urinary tract and gastrointestinal infections recognized as a receptor the glycosylphosphatidylinositol (GPI)-anchored protein decay-accelerating factor (DAF; CD55) at the brush border of cultured human intestinal cells. Results show that Afa/Dr DAEC C1845 bacteria were poorly associated with the mucosa of the gastrointestinal tract of infected mice. We conducted experiments with Chinese hamster ovary (CHO) cells stably transfected with mouse (GPI or transmembrane forms), pig, or human CD55 or mouse Crry cDNAs or transfected with empty vector pDR2EF1α. RecombinantE. coliAAEC185 bacteria expressing Dr or F1845 adhesins bound strongly to CHO cells expressing human CD55 but not to the CHO cells expressing mouse (transmembrane and GPI anchored), rat, or pig CD55 or mouse Crry. Positive clustering of CD55 around Dr-positive bacteria was observed in human CD55-expressing CHO cells but not around the rarely adhering Dr-positive bacteria randomly distributed at the cell surface of CHO cells expressing mouse, rat, or pig CD55.
Processor networks and interconnection networks without long wires (extended abstract)
Authors: Beigel Richard , Kruskal Clydel P.
Published: July 2004

One processor network that is especially attractive for parallel processing is the Butterfly network. A very closely related interconnection network is the Bidelta (or Omega) network. It is well known how to lay out these networks with minimal area, but these layouts use long wires. We show how to lay them out with optimal area and short wires. We also introduce the Mesh-Connected Cycles network, which has optimal area (in the sense of
AT
2
) for a broad range of running times when executing "ascend-descend" algorithms. The length of its longest wire is nearly optimal, and its layout area has very modest constants.
Hardware speedups in long integer multiplication
Authors: Shand M. , Bertin P. , Vuillemin J.
Published: July 2004

We present various experiments in Hardware/Software design tradeoffs met in speeding up long integer multiplications. This work spans over a year, with more than 12 different hardware designs tested and measured.To implement these designs, we rely on our PAM (for
Programmable Active Memory
, see [BRV]) technology which provides us with a 50 millisecond turn-around time silicon foundry for implementing up to 50K gate logic designs fully equipped with fast local RAM and host bus interface.First, we demonstrate how a simple hardware 512 bits integer multiplier coupled with a low end workstation host yields performance on long arithmetic superior to that of the fastest computers for which we could obtain actual benchmark figures.Second, we specialize this hardware in order to speed-up one specific application of long integer arithmetic, namely Rivest-Shamir-Adleman public-key cryptography [RSA]. We demonstrate how a single host driving 3 differently configured PAM boards delivers RSA encryption and decryption faster than 200Kbits/sec for 512 bits keys. This beats the best currently working VLSI specially built for RSA by one order of magnitude.
Task allocation in data flow multiprocessors
Authors: Price Camille C.
Published: July 2004

The performance of data flow multiprocessors depends to a large extent on the methods used to partition a data flow program and assign the resulting computational tasks among the processors. We cite significant contributions to the field of data flow computing, and categorize these efforts according to the granularity of the partitions and by whether task allocation is static (performed at compile time) or dynamic (performed during execution of the program). Each reference is accompanied by a brief description of the task allocation techniques used in the system.
What is scalability?
Authors: Hill Mark D.
Published: July 2004

Scalability
is a frequently-claimed attribute of multiprocessor systems. While the basic notion is intuitive, scalability has no generally-accepted definition. For this reason, current use of the term adds more to marketing potential than technical insight.In this paper, I first examine formal definitions of scalability, but
I fail to lind a useful, rigorous definition of it
. I then question whether scalability is useful and conclude by challenging the technical community to either (1) rigorously define scalability or (2) stop using it to describe systems.
The effect of employing advanced branching mechanisms in superscalar processors
Authors: Oyang Yen-Jen , Wen Chun-Hung , Chen Yu-Fen , Lin Shu-May
Published: July 2004

This paper discusses the effect of employing advanced branching mechanisms in superscalar processors. The motivation behind employing advanced branching mechanisms in superscalar processors is to reduce the control dependence, or in other words the number of branch operations, in the program so that instruction-level parallelism can be exploited more effectively. The second effect achieved by reducing the control dependence in the program is a decrease of the amount of branch penalty due to less branch operations. In this paper, two advanced branching mechanisms are discussed. The first mechanism involves incorporating multiple condition registers in superscalar processors. The second mechanism is a novel multi-way branching scheme proposed in this paper. A quantitative analysis on the effect of the two branching mechanisms shows that incorporating multiple condition registers can boost the superscalar processor performance by a factor of 16% to 20% while employing the proposed multi-way branching mechanism can achieve even greater performance improvement, up to 47%.
A low-cost usage-based replacement algorithm for cache memories
Authors: Deville Yannick
Published: July 2004

Mainly three replacement policies have been used in cache memories : LRU, FIFO and random. LRU achieves higher performance by being usage-based, i.e., by storing the order of the accesses to the cache blocks in order to remove the blocks that have remained unused for the longest period, However, storing this status results in a complex implementation. On the opposite, FIFO and random are non-usage-based ; their implementation is simpler, but their performance is lower. This paper presents the SIDE policy, which achieves a trade-off between the above features : by being usage-based, it yields almost the same performance as LRU. However, it is implemented almost in the same way as FIFO which yields simplicity and makes it easy to design a cache chip performing SIDE or FIFO replacement, depending on the mode chosen.
A high speed mechanism for short branches
Authors: Gunther Bernard K.
Published: July 2004

A semi-absolute branch instruction supplies the low-order bits of the destination address, or an offset into a frame, while the high-order bits the destination address, or frame number, are derived from the current frame number. The branch mechanism proposed here compares a small number of the most significant bits of a current and destination frame offsets followed by a possible increment or decrement of the current frame number, allowing branches to be effected more rapidly, for a given hardware cost, than by adding an offset to the instruction pointer. The increment can be performed upon branching or prior to it in order to hide the latency of the increment operation. If, for example, the three most significant bits of the frame offsets are compared the overall branch range is reduced to 94% of the range of conventional relative branches. This technique over comes the branch range restriction that occurs when the instruction pointer points to near a frame boundary and the destination address is generated by a simple bit-field substitution.
Design for fast DSP machine
Authors: McLaughlin Robert
Published: July 2004

In the following we propose a design for a parallel machine for GHz rate general application Digital Signal Processing, DSP.
A subclass of Petri Nets as design abstraction for parallel architectures
Authors: Joerg Werner B.
Published: July 2004

In spite of their increasing popularity for modeling and performance analysis of parallel systems, Petri nets play only a marginal role in the area of synthesis of asynchronous hardware. It is suggested that a change in the perception of their role will lead to a cost effective design method for parallel asynchronous architectures. A hardware implementable subclass of Petri nets is presented that exploits conflicts as a nondeterministic scheduling feature and that offers token evaluation as an option for path selection. The net primitives, complemented with functional primitives, constitute the lowest abstractions for a data flow oriented design paradigm.
Pointer swizzling at page fault time
Authors: Wilson Paul R.
Published: July 2004

We describe a scheme for supporting huge address spaces without the need for long addresses implemented in hardware. Pointers are translated ("swizzled") from a long format to a shorter format (directly supported by normal hardware) at page fault time. No extra hardware is required beyond that normally used by virtual memory systems, and no continual software cost is incurred by presence checks or indirection of pointers.This scheme could be used to fault pages into a normal memory from a persistent store, or simply to avoid extra hardware requirements when supporting large address spaces. It exploits temporal and spatial locality in much the same way as a normal virtual memory, so its performance should be quite good.
Design and evaluation of a distributed asynchronous VLSI crossbar switch controller for a packet switched supercomputer network
Authors: DuBois Andrew J. , Rasure John
Published: July 2004

A key component in a new high-speed prototype network, called the Multiple Crossbar Network (MCN) being developed at Los Alamos National Laboratory, is a crossbar switching core and its controller. This switching core allows for up to 32 (800 Mbit/second) connections to pass through it simultaneously. The motivation for this network is to allow visualization data to be sent at movie rate speeds to a users workstation from a supercomputer. This paper reviews the key concepts and components of the MCN, and then focuses on the behavioral level design of a distributed asynchronous VLSI controller chip set for the switching core. A unique design methodology is presented and then applied to the controller which uses an externally distributed chip set, and distributed asynchronous finite state machines internally.
A multi-level parallelism architecture
Authors: Ungerer Theo , Zehendner Eberhard
Published: July 2004

This paper describes a parallel programming language and a multi-level parallelism computer architecture, which have been developed by an integrated design process.The ASTOR language is an imperative intermediate language that combines parallel control constructs with a concise module concept. The ASTOR architecture is directed towards reliable execution of programs written in the ASTOR language, utilizing five levels of parallelism expressed by the language constructs. Structure preservation has been applied as a major design principle. The architecture can be characterized as a message passing multiprocessor whose nodes consist of decoupled program flow control and data object processing parts, executing by token-passing similar to large-grain data flow architectures.
The architecture of a memory management unit for object-oriented systems
Authors: Cunha Alberto R. , Ribeiro Carlos N. , Marques José A.
Published: July 2004

We describe the rationale for the design and the architecture of a Memory Management Unit (MMU) for object-oriented systems. The CAMOES
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MMU supports arbitrary size protected objects mapped on a single virtual address space. Support for object invocations is provided in the form of an operations cache closely coupled with the addressing hardware. The MMU only executes in hardware those functions crucial for performance; other functions and, namely, the management of internal buffers and associative memories, and object management policies, are handled in software. This functional organisation is suitable for current generation processors based on RISC principles and is able to support open multi-lingual environments.
An overview of the A architecture for optimisation problems in a logic programming environment
Authors: Rodohan D. P. , Glover R. J.
Published: July 2004

Search of a state space is a common function in artificial intelligence applications consuming a large proportion of the total processing time. In this paper we propose a hierarchical architecture using content addressable memory to accelerate the A* algorithm in a Prolog system and remove the associated high memory overheads.
SPLASH
Authors: Singh Jaswinder Pal , Weber Wolf-Dietrich , Gupta Anoop
Published: July 2004

We present the Stanford Parallel Applications for Shared-Memory (SPLASH), a set of parallel applications for use in the design and evaluation of shared-memory multiprocessing systems. Our goal is to provide a suite of realistic applications that will serve as a well-documented and consistent basis for evaluation studies. We describe the applications currently in the suite in detail, discuss some of their important characteristics, and explore their behavior by running them on a real multiprocessor as well as on a simulator of an idealized parallel architecture. We expect the current set of applications to act as a nucleus for a suite that will grow with time.
Comparison of hypercube, hypernet, and symmetric hypernet architectures
Authors: Kaushal R. P. , Bedi J. S.
Published: July 2004

Hypercube has been the most popular topology for developing multiprocessor supercomputers because of its connectivity, regularity, symmetry and algorithmic mapping properties. However, if a hypercube needs to be expanded at some future time, both hardware configuration and communication software of each node has to be altered because its node degree is not constant. Hwang and Ghosh proposed a new interconnection network called hypernet which has a constant node degree and is easily expandable. However, its components count increases unsymmetrically with the increase in size. We propose a new topology called symmetric hypernet which grows symmetrically with the increase in dimension and hierachical level. The nodes in the symmetric net are functionally and physically separated as IO nodes and computation nodes to avoid traffic congestion and message delays. The IO nodes are placed uniformly among the processing nodes. The system can be dynamically partitioned into subsystems, each of which may be dedicated to serve a user's request(s). The system analysis can be done with the help of analytical models to serve a user's request(s). The system analysis can be done with the help of analytical models to determine how different structures would affect system performance.
A comparison of three current superscalar designs
Authors: Laird Michael
Published: July 2004

A standardized view of superscalar architectures is presented, and three current superscalar designs are comparedusing this framework. The designs studied are the Metaflow Light-ning SPARC, the IBM RS/6000, and the Intel i960MM.
Performance of the HARRIS RTX 2000 Stack Architecture versus the Sun 4 SPARC and the Sun 3 M68020 Architectures
Authors: Keown William F. , Koopman Philip , Collins Aaron
Published: July 2004

This study compares a stack machine, the Harris RTX 2000, a RISC machine, the Sun 4/SPARC, and a CISC machine, the Sun3/M68020. An attempt is made to compare the generic features of each machine which are characteristic of their architectural classes as opposed to being characteristic of the individual machine only. Performance is compared based on execution of the Stanford Integer Benchmark series (12) and on interrupt response characteristics. The data indicates that, for these benchmarks, the RTX stack architecture approaches or exceeds the SPARC machine performance for such measures as total execution cycles required, clock cycles per instruction, native MIPS, static code size, and dynamic instruction count. The 68020 machine is by far the slowest of the three. When scaled to account for disparities in process technology, the RTX 2000 is as fast as (or faster than) the SPARC in actual program execution time, and it has a smaller code size.
Codes to reduce switching transients across VLSI I/O pins
Authors: Park Arvin , Maeder Ron
Published: July 2004

We develop a coding scheme that reduces switching transients by limiting the number of lines that simultaneously switch during transmission of address and data information over the I/O pins of a VLSI chip, or the lines of a system bus. The maximum number of lines that simultaneously switch can be reduced by a factor of two using simple and fast circuitry for encoding and decoding.