bluuebunny/crossref_metadata_2025 huggingface dataset:
S‐adenosylmethionine Metabolism and AFP Expression: Is There a Direct Link?
Authors: BÉLANGER L. , KUNZ G. , HOFFMAN J. , CHIU J. F. , LESCAUT A. , LIAU M. C. , LABERGE C. , DHATT P. S.
Published: February 2009

The parallel behavior of AFP and methionine serum levels in hereditary tyrosinemia has led to the hypothesis that methionine activation and AFP expression are functionally related. The present study was conducted to test this idea. The preliminary experiments reported here were primarily designed to test whether AFP production and methionine adenosyltransferase activity change coordinately during normal development, and whether factors (hormones, injury) which influence AFP production in newborn or adult livers exert a coordinate effect on methionine adenosyltransferase activity or S‐adenosylmethionine pool or vice versa. Some other data are included that relate to the problem, in particular, the serum methionine and AFP levels in children with Indian Childhood Cirrhosis, and the AFP levels in the first days of 3′M‐DAB feeding in rats. The sum of our observations provides little support at this point to the concept of differentiation control at the methionine activation step. If any common denominator exists that promotes AFP production in several liver conditions, and accounts for parallel methionine‐AFP modulations as observed in hereditary tyrosinemia, a more likely candidate might be an acute depletion of liver ATP pool.
Usefulness and Limitation of Carcinoembryonic Proteins as Therapeutic and Prognostic Markers in Malignant Tumors
Authors: OHKURA H. , MUKOJIMA T. , ISHII M. , HATTORI N.
Published: February 2009

Patients with germ cell tumors, hepatomas and other malignant tumors were studied throughout their courses of surgical, radiological and medical treatments with serial determinations of AFP, CEA, HCG and basic fetoprotein (BFP), which was newly found by M. Ishii.

In general, these carcinoembryonic or trophoblastic markers were observed to be well correlated with the fate of the tumor in the body and to be useful in evaluating the effect of treatment or in predicting the prognosis of the patient. Except for a postoperative transient increase in serum BFP and CEA, the levels fell after surgery and rose again with recurrence of the tumor. Although we had some patients with teratocarcinoma, hepatoma or gastric carcinoma, whose serum AFP showed a transient parallelism with their clinical courses, an obvious dissociation in these markers occurred later in their course. Similar dissociations were also observed with these carcinofetal or trophoblastic markers in patients with chemotherapy or radiotherapy for their teratocarcinomas.

We conclude that each carcinoembryonic protein is a useful but limited marker for malignancy but should be used clinically in combination with other tumor markers.
The Effect of Alpha‐fetoprotein on the Immune Response: Diminution of the Phagocytosis Capacity of Macrophages Cultured in vitro in the Presence of Mouse Amniotic Fluid or Alpha‐fetoprotein
Authors: OLINESCU A. , LAKY M. , POPESCU D. E. , DUMITRESCU A. , GANEA D.
Published: February 2009

A study was carried out on the in vitro phagocytosis capacity of mouse peritoneal macrophages cultured in a medium supplemented with mouse amniotic fluid or alpha‐fetoprotein purified from embryo extract. For this purpose 3H‐TdR labelled staphylococci and 51Cr labelled fowl red blood cells were used. Both mouse amniotic fluid and alpha‐fetoprotein inhibited phagocytosis, the antigen being incorporated in smaller amount than in the controls where the medium was supplemented with normal mouse serum.

In contrast to fetal glycoprotein, the presence of serum homologous proteins from adult animals did not inhibit the phagocytosis of macrophages but stimulated it.

The possible biological implications of this phenomenon are discussed.
Experimental Hepatocarcinogenesis in Rat and Cellular Detection of Alpha1‐fetoprotein by Use of Peroxidase Conjugates
Authors: KUHLMANN W. D.
Published: February 2009

Hepatomas were induced in rats by feeding low doses (6 mg/kg) or high doses (20 mg/kg) of N‐nitrosomorpholine (NNM) for 12 and 6 weeks respectively. Necroses of adult hepatocytes and proliferation of oval‐shaped cells occurred only at high doses of NNM. In parallel, early reappearance of alpha1‐fetoprotein (AFP) in sera was observed in rats which were fed high doses of NNM. At this time, AFP was detected in oval‐shaped cells by means of immunoperoxidase staining techniques. Both NNM feeding schedules (low and high doses) resulted in development of hepatomas. At this stage of hepatocarcinogenesis, AFP staining nodules were seen concomitantly with non AFP staining nodules in the same animal. AFP staining cells were populations of distinct neoplastic hepatocytes with a certain degree of retrodifferentiation. Pulse‐chase experiments have shown the highly proliferative character of carcinoma cells from which the AFP staining population was the most proliferating one.
Clinical Significance of Liver Scintigraphy Using 67 Ga and AFP Determination as Screening for Primary Cancer of the Liver
Authors: WEISS W. , EDER G. , KROISS A. , NEUMAYR A. , KAHN P.
Published: February 2009

In 100 patients of a 5 year prospective study, primary cancer of the liver could be demonstrated in almost 100% using AFP determination in the serum and combined 67 Gallium scintigraphy. By separate evaluation of the AFP results or 67 Gallium scintigraphy an accuracy of only 80% could be demonstrated.
Biliary Glycoprotein I (BGP I), a CEA‐crossreactive Substance: Purification and Properties
Authors: SVENBERG T. , HAMMARSTROM S. , HEDIN A.
Published: February 2009

A CEA‐crossreactive substance was purified from human bile. It was termed biliary glycoprotein I (BGPI). The molecular weight of BGP I is about 90,000. The protein part is made up of a single polypeptide chain with a composition similar to that of CEA and NCA. BGP I contains the same monosaccharides as CEA and NCA and shows a similar lectin reactivity. BGP I has antigenic determinants in common with CEA and NCA. In addition it contains unique determinants.
CEA Carcinoma Monitoring by Two RIA
Authors: ZAIDMAN J. L. , ADAM J. , HALEVY A. , HERTZIANU I. , BEN ELIEZER A. , EIDELMAN A. , SIMON D.
Published: February 2009

A comparison was made of the accuracy of two CEA assays by RIA in diagnosis of different cancers. The basis of the study was a consecutive series of 76 patients thought to have bladder, colon, stomach or pancreas pathology, or a space occupying lesion; cancer was the final diagnosis in 46. The RIA assay method of Hoffman‐La Roche and the CIS (Sorin) direct double antibody RIA assay were used for CEA detection. Results were correlated with the clinical and follow up evaluation. Samples were taken before operation, immediately after, and 1,2, 3 and 6 months after. Ninety eight per cent of the patients with a negative diagnosis for cancer had no detectable CEA, or levels below 2.5 ng/ml with Roche assay, and below 8 ng/ml with CIS assay. Abnormal CEA levels were found in the different groups as follows: with the Roche assay bladder—22%, colon—45%, stomach—23%, and pancreas—40%, with the CIS assay bladder—66%, colon—61%, stomach—38% and pancreas—60%. We conclude that neither test is ideal for clinical purposes although the CIS assay is probably more sensitive than the Roche assay. Both assays are useful in the monitoring and detection of recurrent tumors.
An Immunoglobulin M (IgM) Antibody to Carcinoembryonic Antigen (CEA)‐like Antigen in Human Pancreatic Cancer
Authors: HARVEY S. R. , CHU T. MING
Published: February 2009

An immunoglobulin M (IgM) antibody to a carcinoembryonic antigen (CEA)‐like antigen was isolated from the ascites fluid of a patient with pancreatic cancer by ammonium sulfate precipitation (25–55% saturation) and subsequent purification by gel filtrations on Sephadex G‐200 and Sepharose 6B followed by protein A‐Sepharose CL‐4B chromatography. The IgM antibody was found to be in complex with a CEA‐like antigen as revealed by the multiple precipitin lines obtained on immunoelectrophoresis and double diffusion with a mixture of antihuman IgM and anti‐CEA. Dissociation of the complex with 0.2M glycine HCl buffer pH 2.5 and further chromatography on Sepharose CL‐6B. followed by Sepharose 6B separated the IgM antibody from the CEA‐like antigen. The IgM antibody formed an immunoprecipitate upon double diffusion with a homologous CEA cross‐reactive antigen isolated from the liver metastasis of another patient with pancreatic cancer. The antigen (molecular weight 70,000 ± 15,000 daltons) which reacted with the IgM antibody was purified by Con A Sepharose affinity chromatography followed by gel filtration on BioGel A 1.5M. The IgM antibody reacted with tumor antigens from pancreatic cancer only. These results suggest that the human IgM antibody response to antigens may be specific to the tumor type involved.
Phase Specific Profiles of Hepatic Enzyme Activity During Ontogeny and in Experimental Hepatomas in Rats
Authors: MALKIN A. , KELLEN J. A. , CAPLAN B.
Published: February 2009

During ontogeny, in rat liver, enzymes are synthesized in clusters characteristic of specific periods of development. These spurts of activity occur in well‐defined late‐term, neonatal and late suckling periods. To test the hypothesis that malignant transformation is associated with a synchronous arrest in differentiation or by an orderly, stepwise process of dedifferentiation and might therefore be characterized by the presence of an enzyme pattern typical of a specific phase of development, we examined enzyme profiles in the Morris 5123 hepatoma and two of its variants (1–1 and 81‐B), a solid tumor derived from HTC cells and a DEN‐AAF induced hepatoma using a battery of enzymes representative of different phases of ontogeny. None of the experimental tumors investigated exhibited an enzyme pattern consistent with any particular phase of ontogenesis. The data support the view that malignant transformation is associated with a kind of programming that is phenotypically characteristic for a particular tumor, but at the same time appears to reflect a disordered, abnormal pattern of gene expression.
Purification and Some Properties of Novel γ‐Glutamyl Transpeptidase Isoenzyme Occurring in Sera of Patients with Hepatoma
Authors: SAWABU N. , NAKAGEN M. , SENMA T. , HATTORI N. , ISHII M.
Published: February 2009

Novel γ‐glutamyl transpeptidase (γ‐GTP) was purified from ascites or sera obtained from hepatoma patients by means of following procedures including ammonium sulfate fractionation, separation by 2 cycles of preparative polyacrylamide disc electrophoresis and elimination by a technique of immuno‐absorption using affinity chromatography. The purified γ‐GTP was shown to be homogeneous as judged by disc electrophoresis. Some physicochemical properties of the partially purified enzyme obtained at the stage of 2 cycles of preparative disc electrophoresis such as heat stability, pH optimum. Km value for substrate and effect of some cations are reported.
Fetal Isoenzyme Expression in Human Tumor Xenografts1
Authors: SINGER R. M.
Published: February 2009

It has been shown previously that a human cancer cell line (HeLa TCRC‐1) which produces only the Regan isoenzymes of alkaline phosphatase in culture, elaborates a different isoenzyme form when grown in an animal host. This alteration of isoenzyme expression results in the production of an isoenzyme form referred to as oncoamniotic (FL), since it shares many of the characteristics of the enzyme form produced by the FL amnion cell line.

Here we shall report on the alteration of isoenzyme expression in a non‐Regan producing cell line heterotransplanted into an immunosuppressed animal host. HeLa TCRC‐2 is a cell line cloned for the exclusive production of an isoenzyme form which is most similar to adult bone type alkaline phosphatase. This cell line growing in an animal host produces an additional isoenzyme form which appears to be similar to the amniotic (FL) type. The original non‐Regan alkaline phosphatase of this cell line persists, and is co‐expressed during in vivo growth.

When HeLa TCRC‐2 is removed from the animal and placed back into culture, the exclusive production of the adult bone type alkaline phosphatase is restored.

The present report indicates the dramatic alterations in gene expression observed when well characterized cultured cells are heterotransplanted into immunosuppressed animals.
A New Carcinoembryonic Protein Characterized by Basic Property
Authors: ISHII M.
Published: February 2009

A new human fetal antigen, common to several types of carcinomas was found in fetal serum and fetal gut extract. Because this antigen was shown to have an isoelectric point of 9.3, it has been designated basic fetoprotein (BFP). BFP was purified from ascites of a patient with hepatoma by the techniques of QAE‐Sephadex A‐50 chromatography. affinity chromatography. isoelectrofocusing and gel filtration. The purified BFP had a γ‐mobility by electrophoresis and a molecular weight of 124,000 by SDS polyacrylamide gel electrophoresis. Monospecific anti‐BFP was prepared by immunizing a rabbit with the purified BFP.

A radioimmunoassay was developed based on a coprecipitation‐inhibition technique using 125I‐BFP and monospecific anti‐BFP. BFP in human serum was determined by the radioimmunoassay. BFP was detected in sera from all normal subjects. Serum BFP levels were lower than 100 ng/ml in 100 out of 101 normal subjects, lower than 200 ng/ml in 180 out of 204 patients with non‐malignant diseases and higher than 200 ng/ml in 94 out of 251 patients with malignant neoplasms. The determination of BFP in serum was demonstrated to be useful for the diagnosis of various carcinomas.
Long‐term outcome of endoscopic therapy in patients with bile duct injury after cholecystectomy
Authors: Weber Andreas , Feussner Hubertus , Winkelmann Franziska , Siewert Jörg Rüdiger , Schmid Roland M , Prinz Christian
Published: February 2009

Background and Aim:  Bile duct lesions, including leaks and strictures, are immanent complications of open or laparoscopic cholecystectomy. Endoscopic procedures have gained increasing potential as the treatment of choice in the management of postoperative bile duct injuries.

Methods:  Between January 1996 and December 2006, 44 patients with biliary leakages and 12 patients with biliary strictures after cholecystectomy were identified by analyzing the endoscopic retrograde cholangiopancreatography database, clinical records, and cholangiograms. The long‐term follow up of endoscopic treatment in biliary lesions after cholecystectomy was evaluated by this retrospective study.

Results:  In 34 of 35 patients (97%) with peripheral bile duct leakages, endoscopic therapy was successful. Transpapillary endoprothesis and/or nasobiliary drainage were removed after 31 (5–399) days. After stent removal, the median follow‐up period was 81 (11–137) months. In patients with central bile duct leakages, the success rate after median 90 (4–145) days of endoscopic therapy was 66.7% (6/9 patients). The median follow up after stent removal in six successfully treated patients was 70 (48–92) months. Eleven of 12 patients (91.6%) with bile duct strictures had successfully completed stent therapy. The follow‐up period of this patient group was 99 (53–140) months.

Conclusions:  Endoscopic treatment of bile duct lesions after cholecystectomy is effective, particularly in patients with peripheral bile duct leakages and bile duct strictures. Therefore, it should be the first‐line therapy used in these patients. Although endoscopic management is less successful in patients with central bile duct leakages, an attempt is warranted.
Site‐specific cleavage of HCV genomic RNA and its cloned core and NS5B genes by DNAzyme
Authors: Kumar Deepak , Chaudhury Indrajit , Kar Premashis , Das Rakha H
Published: February 2009

Background and Aims:  The 9600 nt hepatitis C virus (HCV) genomic RNA has only one internal ribosome entry site (IRES) for translation to a single polyprotein. In search of nucleic acid‐based antiviral agents, two 10‐23 DNAzymes were designed to cleave the RNA in IRES and RNA dependent RNA polymerase (RDRP/NS5B) regions to prevent translation and replication of HCV RNA.

Methods:  In vitro cleavage of HCV RNA by IRES specific DNAzyme, CDz and NS5B specific DNAzyme, NDz was carried out using HCV genomic RNA and in vitro synthesized runoff transcripts of core and NS5B genes. Cleavage of core and NS5B mRNAs by DNAzyme (Dz) in HepG2 cells was assessed by reverse transcription polymerase chain reaction (RT‐PCR) using RNA from cells co‐transfected with cloned core or NS5B gene and its respective DNAzyme. Suppression of core or NS5B protein expression due to mRNA cleavage by Dz in co‐transfected cells was determined by Western blot analysis and fluorescence intensity of fluorescent‐tagged expressed protein. Reduction of NS5B protein activity in NDz co‐transfected cells was determined by enzymatic assays.

Results:  The designed CDz and NDz cleaved HCV genomic RNA and their respective in vitro generated transcripts. Both mRNA and protein expressions of core or NS5B from their cloned genes reduced substantially when co‐transfected with respective Dz. Reduction of RDRP expression by NDz was accompanied with its reduced enzyme activity. Increased RNA cleavage, inhibition of protein expression, and reduction of RDRP activity were observed on increasing Dz concentration.

Conclusion:  Core and NS5B targeted DNAzymes can be used in controlling the replication of HCV RNA.
When does greater mortality increase population size? The long history and diverse mechanisms underlying the hydra effect
Authors: Abrams Peter A.
Published: February 2009

The phenomenon of a population increasing in response to an increase in its per‐capita mortality rate has recently been termed the ‘hydra effect’. This article reviews and unifies previous work on this phenomenon. Some discrete models of density‐dependent growth were shown to exhibit hydra effects in 1954, but the topic was then ignored for decades. Here the history of research on the hydra effect is reviewed, and the key factors producing it are explored. Mortality that precedes overcompensatory density dependence always has the potential to produce hydra effects. Even when mortality follows density dependence, hydra effects may occur in unstable systems due to changes in the amplitude and/or form of population cycles. An increase in resource productivity due to lower consumption rates following increased consumer mortality can also produce a hydra effect. Lower consumption can come about as the result of increased satiation of the consumers or changes in behaviour of either consumer or resource species that reduce the mean attack rate. Changes in species composition of a resource community may also decrease the average attack rate. Population structure can promote hydra effects by allowing separation of the timing of density dependence and mortality, although stage‐specific density dependence usually decreases hydra effects.
Examination of evolutionary relationships in the Cape fossorial skink species complex (Acontinae: Acontias meleagris meleagris) reveals the presence of five cryptic lineages
Authors: Daniels Savel R. , Heideman Neil J. L. , Hendricks Martin G. J.
Published: February 2009

Variable morphological characters have obscured genealogical relationships in the Cape fossorial skink Acontias meleagris meleagris species complex. Currently the species complex contains four dubious operational taxonomic units (A. meleagris meleagris, A. m. orientalis, A. percivali tasmani and the morph lineicauda) with poorly defined species boundaries. In the present study we examine the evolutionary relationships within the species complex by sampling 24 skink populations from the known geographical distribution in the Western and Eastern Cape provinces of South Africa, representing a total of 119 specimens. We used partial sequence data derived from two mitochondrial DNA genes, 16S rRNA and COI, and one nuclear DNA gene, intron β‐fibrinogen (β‐fibint 7), to examine evolutionary relationships. Phylogenetic relationships were determined using both Maximum Parsimony (MP) and Bayesian inference (BI) from the combined mtDNA, nDNA and the total evidence data. Additionally we employed Maximum likelihood (ML) analyses on the total evidence data that comprised ∼1.5 kb. Topologies derived from the combined mtDNA analyses were congruent with the total evidence analyses (mtDNA + nDNA) and retrieved five major clades with strong statistical support inferred from bootstrapping and posterior probabilities. The five clades were genealogically and geographically exclusive, diagnostic at both the mtDNA and nDNA level and characterized by pronounced sequence divergence, with no shared haplotypes between clades. Collectively these results suggest the presence of five putative cryptic operational taxonomic units within the A. meleagris meleagris species complex. Constraining the traditionally recognized taxa always retrieved a statistically worse topology suggesting that considerable taxonomic revision is required. Our results indicate that traditional morphological characters need to be reassessed to define the five novel lineages in the A. meleagris meleagris species complex. The phylogeographic pattern for the fossorial skinks we retrieved was novel compared to phylogeographic studies for codistributed above ground living taxa. These results suggest that the abiotic and biotic factors that impact subterranean taxa may differ from supraterranean taxa.
Physical Restraint of People with Intellectual Disability: A Review of Implementation Reduction and Elimination Procedures
Authors: Luiselli James K.
Published: February 2009

Background  This review describes procedures to reduce and eliminate physical restraint of people with intellectual disability. One approach is to assess antecedent conditions associated with restraint and change them so that they no longer produce restraint‐provoking behaviour. A second approach is to decrease the duration of restraint by establishing a fixed‐time release (FTR) criterion.

Methods  Research supporting these approaches within community‐based service settings are presented.

Results  Physical restraint can be effectively reduced and eliminated using antecedent intervention procedures and FTR contingencies.

Conclusions  Future research on physical restraint reduction and elimination should be conducted among people with intellectual disability. Intervention should include explicit therapeutic goals and methods that are acceptable to service providers. Outcome evaluation should focus on long‐term follow‐up over months and years. Finally, organizations serving people who have intellectual disability should approach physical restraint reduction and elimination by dedicating sufficient resources and adopting evidence‐based practices.
An Analysis of the Distribution and Social Antecedents of Restrictive Behavioural Practices in a Community Day Service for Adults with Intellectual Disabilities
Authors: Finn Lori L. , Sturmey Peter
Published: February 2009

Background  Community service providers strive to reduce the use of restrictive behavioural procedures, but little is known about their use in community services. Therefore, this study analysed the distribution among service users and antecedents to the use of restrictive procedures.

Materials  The authors analysed records of the use of restrictive behavioural procedures for 81 adults with intellectual disabilities, behavioural and mental health challenges who attended a community day programme. The authors obtained data from one quarter in each of three consecutive years. The authors analysed the frequency of restrictive procedures by individual and the frequency of antecedents to the use of restrictive procedures.

Results  A small proportion of service users accounted for all use of restrictive procedures. This was true for all three data sets. We coded antecedents to the use of restrictive procedures reliably. The most common antecedents were transitions and seatwork.

Conclusion  Restrictive behavioural procedures are concentrated among a small proportion of service users and occasions. Efforts to reduce the use of restrictive procedures should first identify these service users and occasions and then focus efforts to reduce restrictive procedures there. Information concerning the antecedents of restrictive behavioural procedures may be useful as part of a descriptive assessment to design individual interventions to reduce restrictive procedures.
Interactions Between HERC2, OCA2 and MC1R May Influence Human Pigmentation Phenotype
Authors: Branicki Wojciech , Brudnik Urszula , Wojas‐Pelc Anna
Published: February 2009

Human pigmentation is a polygenic trait which may be shaped by different kinds of gene–gene interactions. Recent studies have revealed that interactive effects between HERC2 and OCA2 may be responsible for blue eye colour determination in humans. Here we performed a population association study, examining important polymorphisms within the HERC2 and OCA2 genes. Furthermore, pooling these results with genotyping data for MC1R, ASIP and SLC45A2 obtained for the same population sample we also analysed potential genetic interactions affecting variation in eye, hair and skin colour. Our results confirmed the association of HERC2 rs12913832 with eye colour and showed that this SNP is also significantly associated with skin and hair colouration. It is also concluded that OCA2 rs1800407 is independently associated with eye colour. Finally, using various approaches we were able to show that there is an interaction between MC1R and HERC2 in determination of skin and hair colour in the studied population sample.
Irritability is associated with anxiety and greater severity, but not bipolar spectrum features, in major depressive disorder
Authors: Perlis R. H. , Fava M. , Trivedi M. H. , Alpert J. , Luther J. F. , Wisniewski S. R. , John Rush A.
Published: February 2009

Objective:  Irritability is common during major depressive episodes, but its clinical significance and overlap with symptoms of anxiety or bipolar disorder remains unclear. We examined clinical correlates of irritability in a confirmatory cohort of Sequenced Treatment Alternatives to Relieve Depression (STAR*D) study participants with major depressive disorder (MDD).

Method:  Logistic regression was used to identify features associated with presence of irritability on the clinician‐rated Inventory of Depressive Symptomatology.

Results:  Of 2307 study participants, 1067(46%) reported irritability at least half the time during the preceding week; they were more likely to be female, to be younger, to experience greater depression severity and anxiety, and to report poorer quality of life, prior suicide attempts and suicidal ideation. Bipolar spectrum features were not more common among those with irritability.

Conclusion:  Irritable depression is not a distinct subtype of MDD, but irritability is associated with greater overall severity, anxiety comorbidity and suicidality.
QSAR Modelling for Mutagenic Potency of Heteroaromatic Amines by Optimal SMILES‐based Descriptors
Authors: Toropov Andrey A. , Toropova Alla P. , Benfenati Emilio
Published: February 2009

We used simplified molecular input line entry system to construct optimal descriptors for modelling of the mutagenic potency of heteroaromatic amines by quantitative structure–activity relationships. Statistical characteristics of the model are n = 67, r 2 = 0.8639, r 2CV = 0.8560, s = 0.737, F = 413 (training set); and n = 28, r 2 = 0.8760, r 2CV = 0.8560, s = 0.644, F = 184 (test set). The r 2CV is the cross‐validation correlation coefficient.
A Parametric Model for Ionization Current in a Four Stroke SI Engine
Authors: Andersson Ingemar , Eriksson Lars
Published: February 2009

A model for the thermal part of an ionization signal is presented that connects the ionization current to cylinder pressure and temperature in a spark ignited internal combustion engine. One strength of the model is that, after calibration, it has only two free parameters: burn angle and initial kernel temperature. By fitting the model to a measured ionization signal, it is possible to estimate both cylinder pressure and temperature, where the pressure is estimated with good accuracy. The model approach is validated on engine data. Cylinder pressure and ionization current data were collected on a Saab four-cylinder spark ignited engine for a variation in ignition timing and air-fuel ratio. The main result is that the parametrized ionization current model can be used to estimating combustion properties as pressure, temperature, and content of nitric oxides based on measured ionization currents. The current status of the model is suitable for off-line analysis of ionization currents and cylinder pressure. This ionization current model not only describes the connection between the ionization current and the combustion process, but also offers new possibilities for engine management system to control the internal combustion engine.
Energy Dissipation in Dynamical Systems Through Sequential Application and Removal of Constraints
Authors: Issa Jimmy , Mukherjee Ranjan , Diaz Alejandro R.
Published: February 2009

A strategy to remove energy from finite-dimensional elastic systems is presented. The strategy is based on the cyclic application and removal of constraints that effectively remove and restore degrees of freedom of the system. In general, application of a constraint removes kinetic energy from the system, while removal of the constraint resets the system for a new cycle of constraint application. Conditions that lead to a net loss in kinetic energy per cycle and bounds on the amount of energy removed are presented. In linear systems, these bounds are related to the modes of the system in its two states, namely, with and without constraints. It is shown that energy removal is always possible, even using a random switching schedule, except in one scenario, when energy is trapped in modes that span an invariant subspace with special orthogonality properties. Applications to nonlinear systems are discussed. Examples illustrate the process of energy removal in both linear and nonlinear systems.
Internal Model Control for Dynamic Systems With Preceded Backlash
Authors: Dong Ruili , Tan Yonghong
Published: February 2009

A discrete-time internal model control approach for nonsmooth nonlinear systems described by a pseudo-Hammerstein model with backlash is presented. In this method, the controlled system is described by the pseudo-Hammerstein model, and the corresponding inverse model is constructed. Considering the existence of the model mismatch, the internal model control is implemented. As the model is switched among the different operating zones, the piecewise robust filters are proposed to improve the robust stability and transient performance of the control system. Finally, the simulation results based on the proposed method for a mechanical transmission system are presented.
Sliding Mode Control of a 2DOF Planar Pneumatic Manipulator
Authors: Van Damme Michaël , Vanderborght Bram , Van Ham Ronald , Verrelst Björn , Daerden Frank , Lefeber Dirk
Published: February 2009

This paper presents a sliding mode controller for a 2DOF planar pneumatic manipulator actuated by pleated pneumatic artificial muscle actuators. It is argued that it is necessary to account for the pressure dynamics of muscles and valves. A relatively detailed system model that includes pressure dynamics is established. Since the model includes actuator dynamics, feedback linearization was necessary to design a sliding mode controller. The feedback linearization and subsequent controller design are presented in detail, and the controller’s performance is evaluated, both in simulation and experimentally. Chattering was found to be quite severe, so the introduction of significant boundary layers was required.
Nonsingular Serret–Frenet Based Path Following Control for an Underactuated Surface Vessel
Authors: Ghommam Jawhar , Mnif Faïçal , Benali Abederraouf , Derbel Nabil
Published: February 2009

In this paper we develop a new control law to steer an underactuated surface vessel along a predefined path at a constant forward speed controlled by the main thruster system. The methodology is based on the Serret–Frenet formulation to represent the ship kinematics in terms of path parameters, which allows for convenient definition of cross and along track error. Furthermore, our approach for path following overcomes the stringent initial condition constraints. This paper also addresses the path following with environmental disturbances induced by wave, wind, and ocean-current. The proposed controller is designed based on the Lyapunov direct method and backstepping technique. The closed loop path following errors is proven to be uniform ultimate bounded. Results are demonstrated by high fidelity simulation.
Sampled-Data Stabilization of a Class of Nonlinear Systems With Application in Robotics
Authors: Pertew A. M. , Marquez H. J. , Zhao Q.
Published: February 2009

The output feedback stabilization problem for the class of nonlinear Lipschitz systems is considered. A discrete-time feedback controller is designed for the sampled-data case, where the output of the plant is only available at discrete points of time and where the objective is to stabilize the system continuously using a discrete-time controller. We show that exact stabilization in this case can be achieved using a direct sampled-data design approach, based on H∞ optimization theory, in which neither the plant model nor the controller need to be discretized a priori. The proposed design is solvable using commercially available software and is shown to have important advantages over the classical emulation approach that has been used to solve similar problems. The applicability of the proposed techniques in the robotics field is thoroughly discussed from both the modeling and design perspectives.
Minimum-Time/Energy, Output Transitions for Dual-Stage Systems
Authors: Iamratanakul Dhanakorn , Devasia Santosh
Published: February 2009

This article addresses the optimal (minimum-time/energy) trajectory design for changing the output from one value y̱ to another y¯ within a finite time interval [0,tf] called the output-transition time interval. The output should be maintained constant (at the desired value) outside the output-transition time interval. The main contribution of this article is to establish the existence of a solution to the problem when preactuation (input applied during time t<0) and postactuation (input applied during time t>tf) are allowed. The advantage of using pre- and postactuation inputs is illustrated with an experimental dual-stage actuator system.
Improvements of Particle Near-Wall Velocity and Erosion Predictions Using a Commercial CFD Code
Authors: Zhang Yongli , McLaury Brenton S. , Shirazi Siamack A.
Published: February 2009

The determination of a representative particle impacting velocity is an important component in calculating solid particle erosion inside pipe geometry. Currently, most commercial computational fluid dynamics (CFD) codes allow the user to calculate particle trajectories using a Lagrangian approach. Additionally, the CFD codes calculate particle impact velocities with the pipe walls. However, these commercial CFD codes normally use a wall function to simulate the turbulent velocity field in the near-wall region. This wall-function velocity field near the wall can affect the small particle motion in the near-wall region. Furthermore, the CFD codes assume that particles have zero volume when particle impact information is being calculated. In this investigation, particle motions that are simulated using a commercially available CFD code are examined in the near-wall region. Calculated solid particle erosion patterns are compared with experimental data to investigate the accuracy of the models that are being used to calculate particle impacting velocities. While not considered in particle tracking routines in most CFD codes, the turbulent velocity profile in the near-wall region is taken into account in this investigation, and the effect on particle impact velocity is investigated. The simulation results show that the particle impact velocity is affected significantly when near-wall velocity profile is implemented. In addition, the effects of particle size are investigated in the near-wall region of a turbulent flow in a 90 deg sharp bend. A CFD code is modified to account for particle size effects in the near-wall region before and after the particle impact. It is found from the simulations that accounting for the rebound at the particle radius helps avoid nonphysical impacts and reduces the number of impacts by more than one order-of-magnitude for small particles (25 μm) due to turbulent velocity fluctuations. For large particles (256 μm), however, nonphysical impacts are not observed in the simulations. Solid particle erosion is predicted before and after introducing these modifications, and the results are compared with experimental data. It is shown that the near-wall modification and turbulent particle interactions significantly affect the simulation results. Modifications can significantly improve the current CFD-based solid particle erosion modeling.
Development of an analytical solution of modified Biot’s equations for the optimization of lightweight acoustic protection
Authors: Kanfoud Jamil , Ali Hamdi Mohamed , Becot François-Xavier , Jaouen Luc
Published: February 2009

During lift-off, space launchers are submitted to high-level of acoustic loads, which may damage sensitive equipments. A special acoustic absorber has been previously integrated inside the fairing of space launchers to protect the payload. A new research project has been launched to develop a low cost fairing acoustic protection system using optimized layers of porous materials covered by a thin layer of fabric. An analytical model is used for the analysis of acoustic wave propagation within the multilayer porous media. Results have been validated by impedance tube measurements. A parametric study has been conducted to determine optimal mechanical and acoustical properties of the acoustic protection under dimensional thickness constraints. The effect of the mounting conditions has been studied. Results reveal the importance of the lateral constraints on the absorption coefficient particularly in the low frequency range. A transmission study has been carried out, where the fairing structure has been simulated by a limp mass layer. The transmission loss and noise reduction factors have been computed using Biot’s theory and the local acoustic impedance approximation to represent the porous layer effect. Comparisons between the two models show the frequency domains for which the local impedance model is valid.
Melody recognition by two-month-old infants
Authors: Plantinga Judy , Trainor Laurel J.
Published: February 2009

Music is part of an infant’s world even before birth, and caregivers around the world sing to infants. Yet, there has been little research into the musical abilities or preferences of infants younger than 5months. In this study, the head turn preference procedure used with older infants was adapted into an eye-movement preference procedure so that the ability of 2-month-old infants to remember a short melody could be tested. The results show that with minimal familiarization, 2-month-old infants remember a short melody and can discriminate it from a similar melody.
Density imaging using inverse scattering
Authors: Lavarello Roberto J. , Oelze Michael L.
Published: February 2009

Inverse scattering is considered one of the most robust and accurate ultrasonic tomography methods. Most inverse scattering formulations neglect density changes in order to reconstruct sound speed and acoustic attenuation. Some studies available in literature suggest that density distributions can also be recovered using inverse scattering formulations. Two classes of algorithms have been identified. (1) The separation of sound speed and density contributions from reconstructions using constant density inverse scattering algorithms at multiple frequencies. (2) The inversion of the full wave equation including density changes. In this work, the performance of a representative algorithm for each class has been studied for the reconstruction of circular cylinders: the dual frequency distorted Born iterative method (DF-DBIM) and the T-matrix formulation. Root mean square error values lower than 30% were obtained with both algorithms when reconstructing cylinders up to eight wavelengths in diameter with moderate density changes. However, in order to provide accurate reconstructions the DF-DBIM and T-matrix method required very high signal-to-noise ratios and significantly large bandwidths, respectively. These limitations are discussed in the context of practical experimental implementations.
A study of lip movements during spontaneous dialog and its application to voice activity detection
Authors: Sodoyer David , Rivet Bertrand , Girin Laurent , Savariaux Christophe , Schwartz Jean-Luc , Jutten Christian
Published: February 2009

This paper presents a quantitative and comprehensive study of the lip movements of a given speaker in different speech/nonspeech contexts, with a particular focus on silences (i.e., when no sound is produced by the speaker). The aim is to characterize the relationship between “lip activity” and “speech activity” and then to use visual speech information as a voice activity detector (VAD). To this aim, an original audiovisual corpus was recorded with two speakers involved in a face-to-face spontaneous dialog, although being in separate rooms. Each speaker communicated with the other using a microphone, a camera, a screen, and headphones. This system was used to capture separate audio stimuli for each speaker and to synchronously monitor the speaker’s lip movements. A comprehensive analysis was carried out on the lip shapes and lip movements in either silence or nonsilence (i.e., speech+nonspeech audible events). A single visual parameter, defined to characterize the lip movements, was shown to be efficient for the detection of silence sections. This results in a visual VAD that can be used in any kind of environment noise, including intricate and highly nonstationary noises, e.g., multiple and/or moving noise sources or competing speech signals.
Helmholtz-like resonators for thermoacoustic prime movers
Authors: Andersen Bonnie J. , Symko Orest G.
Published: February 2009

In a thermoacoustic prime mover, high acoustic output power can be achieved with a large-diameter stack and with a cavity with a large volume attached at the open end of the resonator containing the stack. The combination of resonator and cavity makes the device Helmholtz-like, with special characteristics of the resonant frequencies and quality factor, Q. Analysis of its acoustic behavior based on a model of a closed bottle presents features that are useful for the development of such prime movers for energy conversion from heat to sound. In particular, the arrangement produces in the cavity a high sound level, which is determined by the Q of the system. Comparison with a half-wave resonator type of prime mover, closed at both ends, shows the advantages of the Helmholtz-like device.
Continuous versus discrete frequency changes: Different detection mechanisms?
Authors: Demany Laurent , Carlyon Robert P. , Semal Catherine
Published: February 2009

Sek and Moore [J. Acoust. Soc. Am. 106, 351–359 (1999)] and Lyzenga et al. [J. Acoust. Soc. Am. 116, 491–501 (2004)] found that the just-noticeable frequency difference between two pure tones relatively close in time is smaller when these tones are smoothly connected by a frequency glide than when they are separated by a silent interval. This “glide effect” was interpreted as evidence that frequency glides can be detected by a specific auditory mechanism, not involved in the detection of discrete, time-delayed frequency changes. Lyzenga et al. argued in addition that the glide-detection mechanism provides little information on the direction of frequency changes near their detection threshold. The first experiment reported here confirms the existence of the glide effect, but also shows that it disappears when the glide is not connected smoothly to the neighboring steady tones. A second experiment demonstrates that the direction of a 750ms frequency glide can be perceptually identified as soon as the glide is detectable. These results, and some other observations, lead to a new interpretation of the glide effect, and to the conclusion that continuous frequency changes may be detected in the same manner as discrete frequency changes.
The direct simulation of acoustics on Earth, Mars, and Titan
Authors: Hanford Amanda D. , Long Lyle N.
Published: February 2009

With the recent success of the Huygens lander on Titan, a moon of Saturn, there has been renewed interest in further exploring the acoustic environments of the other planets in the solar system. The direct simulation Monte Carlo (DSMC) method is used here for modeling sound propagation in the atmospheres of Earth, Mars, and Titan at a variety of altitudes above the surface. DSMC is a particle method that describes gas dynamics through direct physical modeling of particle motions and collisions. The validity of DSMC for the entire range of Knudsen numbers (Kn), where Kn is defined as the mean free path divided by the wavelength, allows for the exploration of sound propagation in planetary environments for all values of Kn. DSMC results at a variety of altitudes on Earth, Mars, and Titan including the details of nonlinearity, absorption, dispersion, and molecular relaxation in gas mixtures are given for a wide range of Kn showing agreement with various continuum theories at low Kn and deviation from continuum theory at high Kn. Despite large computation time and memory requirements, DSMC is the method best suited to study high altitude effects or where continuum theory is not valid.
The dependencies of phase velocity and dispersion on volume fraction in cancellous-bone-mimicking phantoms
Authors: Wear Keith A.
Published: February 2009

Frequency-dependent phase velocity was measured in eight cancellous-bone-mimicking phantoms consisting of suspensions of randomly oriented nylon filaments (simulating trabeculae) in a soft-tissue-mimicking medium (simulating marrow). Trabecular thicknesses ranged from 152to356μm. Volume fractions of nylon filament material ranged from 0% to 10%. Phase velocity varied approximately linearly with frequency over the range from 300to700kHz. The increase in phase velocity (compared with phase velocity in a phantom containing no filaments) at 500kHz was approximately proportional to volume fraction occupied by nylon filaments. The derivative of phase velocity with respect to frequency was negative and exhibited nonlinear, monotonically decreasing dependence on volume fraction. The dependencies of phase velocity and its derivative on volume fraction in these phantoms were similar to those reported in previous studies on (1) human cancellous bone and (2) phantoms consisting of parallel nylon wires immersed in water.