bluuebunny/crossref_metadata_2025 huggingface dataset:
Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry and nuclear magnetic resonance analyses of end‐functionalized saccharidic polymers: an example of a useful analytical technique combination
Authors: D'Agosto F. , Charreyre M. T. , Pichot C. , Dessalces G. , Delolme F.
Published: March 2004

The living cationic polymerization of a saccharidic monomer (1,2:3,4‐di‐O‐isopropylidene‐6‐O‐(2‐vinyloxyethyl)‐D‐galactopyranose, GVE) gives rise to aldehyde end‐capped polymers (PGVECHO) of low molar masses (<10 000 Da) and low molar mass distribution (<1.2). These polymers were derivatized by selective introduction of either hexamethylenediamine (PGVE‐NH2) or 9‐fluorenylmethyl carbazate (PGVE‐Fmoc) end groups. The resulting polymers were fully characterized by complementary use of nuclear magnetic resonance (1H NMR) and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS). The expected structure according to the polymerization mechanism, the occurrence of side reactions and the success of the post‐functionalization reactions were confirmed. Copyright © 2004 John Wiley & Sons, Ltd.
The formation of complexes by tetraethylresorcarene with planar guest ions studied by electrospray ionisation Fourier transform ion cyclotron resonance mass spectrometry
Authors: Mäkinen Marko , Vainiotalo Pirjo
Published: March 2004

Resorcarenes have become a popular subject of study in the field of supramolecular chemistry. In this work the formation of host–guest complexes between a synthetic macrocyclic host, tetraethylresorcarene, and various eligible planar guests, was studied by mass spectrometric methods. The size and nature of the guest ion strongly influenced the complex formation. Collision‐induced dissociation experiments revealed the fragmentation patterns of the resorcarene skeleton and the differences in fragmentation induced by the guest ions. Copyright © 2004 John Wiley & Sons, Ltd.
Collision‐activated cleavage of a peptide/antibiotic disulfide linkage: possible evidence for intramolecular disulfide bond rearrangement upon collisional activation
Authors: Fagerquist Clifton K.
Published: March 2004

Ceftiofur is an important veterinary β‐lactam antibiotic whose bioactive metabolite, desfuroylceftiofur, has a free thiol group. Desfuroylceftiofur (DFC) was reacted with two peptides, [Arg8]‐vasopressin and reduced glutathione, both of which have cysteine residues to form disulfide‐linked peptide/antibiotic complexes. The products of the reaction, [vasopressin + (DFC‐H) + (DFC‐H) + H]+, [(vasopressin+H) + (DFC‐H) + H]+ and [(glutathione‐H) + (DFC‐H) + H]+, were analyzed using collision‐activated dissociation (CAD) with a quadrupole ion trap tandem mass spectrometer. MS/MS of [vasopressin + (DFC‐H) + (DFC‐H) + H]+ resulted in facile dissociative loss of one and two covalently bound DFC moieties. Loss of one DFC resulted from either homolytic or heterolytic dissociation of the peptide/antibiotic disulfide bond with equal or unequal partitioning of the two sulfur atoms between the fragment ion and neutral loss. Hydrogen migration preceded heterolytic dissociation. Loss of two DFC moieties from [vasopressin + (DFC‐H) + (DFC‐H) + H]+ appears to result from collision‐activated intramolecular disulfide bond rearrangement (IDBR) to produce cyclic [vasopressin + H]+ (at m/z 1084) as well as other cyclic fragment ions at m/z 1084 ± 32 and +64. The cyclic structure of these ions could only be inferred as MS/MS may result in rearrangement to non‐cyclic structures prior to dissociative loss. IDBR was also detected from MS3 experiments of [vasopressin + (DFC‐H) + (DFC‐H) + H]+ fragment ions. MS/MS of [(glutathione‐H) + (DFC‐H) + H]+ resulted in cleavage of the peptide backbone with retention of the DFC moiety as well as heterolytic cleavage of the peptide/antibiotic disulfide bond to produce the fragment ion: [(DFC‐2H) + H]+. These results demonstrate the facile dissociative loss by CAD of DFC moieties covalently attached to peptides through disulfide bonds. Published in 2004 by John Wiley & Sons, Ltd.
Electron ionization induced fragmentation of some oxadiazole and thiadiazole derivatives
Authors: Pihlaja Kalevi , Agirbas Hikmet , Ovcharenko Vladimir , Valtamo Pauliina
Published: March 2004

The mass spectrometric behaviour under electron ionization of several 3,4‐(alkyl/aryl)‐disubstituted 1,2,4‐oxadiazole‐5(4H)‐ones (1–13) and 1,2,4‐thiadiazole‐5(4H)‐thiones (14–17), and that of 3‐aryl‐5‐alkyl‐ or arylthio‐1,2,4‐thiadiazoles (18–24), was studied. These five‐membered rings split similarly to the corresponding 1,2,4‐thiadiazole‐5(4H)‐ones, although substitution has also a clear effect on the routes of fragmentation and the magnitude of secondary processes. In particular, the fragmentation of 1,2,4‐oxadiazole‐5(4H)‐ones (1–6), which do not bear aromatic substituents, was, in addition to the ring ruptures, fairly complicated. The other compounds fragmented more systematically and relatively few unpredictable fragmentations occurred. Copyright © 2004 John Wiley & Sons, Ltd.
Sensitive determination of acidic drugs and triclosan in surface and wastewater by ion‐pair reverse‐phase liquid chromatography/tandem mass spectrometry
Authors: Quintana José Benito , Reemtsma Thorsten
Published: March 2004

A new method is presented for the determination of 12 acidic pharmaceuticals (non‐steroidal anti‐inflammatory drugs and bezafibrate), including two metabolites from aqueous samples, together with triclosan as a personal care product. Ion‐pair liquid chromatography (IP‐LC) with electrospray ionisation tandem mass spectrometry (ESI‐MS) in the negative ion mode was employed. The ion‐pairing agent (tri‐n‐butylamine) increased the signal intensity for all acidic analytes and detection limits of 6–200 ng/L were obtained by multiple reaction monitoring. This allows analysis of wastewater samples by direct injection into the LC/MS system without the need for a preceding enrichment step. When combined with a solid‐phase extraction (SPE) step, limits of quantification between 0.15 and 11 ng/L were obtained from 100‐mL sample volumes, which is adequate for most applications. The occurrence of matrix effects was studied and standard addition was required for reliable quantification after SPE from wastewater. The method was finally applied to surface and wastewaters, with analyte concentrations ranging from below the detection limit up to 5.5 μg/L. Copyright © 2004 John Wiley & Sons, Ltd.
Novel experimental arrangement developed for direct fullerene analysis by electrospray time‐of‐flight mass spectrometry
Authors: Kozlovski V. , Brusov V. , Sulimenkov I. , Pikhtelev A. , Dodonov A.
Published: March 2004

A novel electrospray setup was found effective for direct analysis of fullerene solutions by electrospray (ES) mass spectrometry. The electrospray capillary needle used for the analysis is equipped with a thin metal (copper, platinum or stainless steel) wire installed inside the capillary. The wire tip protrudes slightly from the capillary end. In this configuration the high electrical field formed by the wire tip stimulates a specific electrospray mode with a fine spray originating from the tip. The correlation of the acquired mass spectra with the magnified view of the spray at the capillary tip was investigated. The effective formation of fullerene ions in both negative and positive ion modes was observed in mass spectra only in the specific case of the electrospray originating from the wire tip. The fullerene di‐anions observed in the negative ES mass spectra provide evidence for the electrochemical nature of this process occurring at the ES capillary tip. Observation of fullerene ions in mass spectra obtained using the suggested electrospray arrangement is assumed to be a consequence of the fine spray originating from the sharp metal wire tip. In this case the liquid/metal interface is near the Taylor cone apex. Copyright © 2004 John Wiley & Sons, Ltd.
High‐throughput simultaneous determination of plasma water deuterium and 18‐oxygen enrichment using a high‐temperature conversion elemental analyzer with isotope ratio mass spectrometry
Authors: Richelle M. , Darimont C. , Piguet‐Welsch C. , Fay L. B.
Published: March 2004

This paper presents a high‐throughput method for the simultaneous determination of deuterium and oxygen‐18 (18O) enrichment of water samples isolated from blood. This analytical method enables rapid and simple determination of these enrichments of microgram quantities of water. Water is converted into hydrogen and carbon monoxide gases by the use of a high‐temperature conversion elemental analyzer (TC‐EA), that are then transferred on‐line into the isotope ratio mass spectrometer. Accuracy determined with the standard light Antartic precipitation (SLAP) and Greenland ice sheet precipitation (GISP) is reliable for deuterium and 18O enrichments. The range of linearity is from 0 up to 0.09 atom percent excess (APE, i.e. −78 up to 5725 delta per mil (dpm)) for deuterium enrichment and from 0 up to 0.17 APE (−11 up to 890 dpm) for 18O enrichment. Memory effects do exist but can be avoided by analyzing the biological samples in quintuplet. This method allows the determination of 1440 samples per week, i.e. 288 biological samples per week. Copyright © 2004 John Wiley & Sons, Ltd.
Anisole, a new dopant for atmospheric pressure photoionization mass spectrometry of low proton affinity, low ionization energy compounds
Authors: Kauppila Tiina J. , Kostiainen Risto , Bruins Andries P.
Published: March 2004

Atmospheric pressure photoionization (APPI) is a novel method of ionization in liquid chromatography/mass spectrometry (LC/MS). It was originally developed in order to broaden the range of LC/MS ionizable compounds towards less polar compounds that cannot be analyzed by electrospray (ESI) and atmospheric pressure chemical ionization (APCI). Studies done thus far have shown that non‐polar compounds that earlier were not ionizable in LC/MS can indeed be ionized by the use of APPI. However, the best ionization efficiency for low polarity samples has been achieved with low proton affinity (PA) solvents that are not suitable in reversed‐phase LC (RP‐LC). Here it is demonstrated that the signals for analytes with low proton affinities in acetonitrile can be increased 100‐fold by using anisole as the dopant for APPI, which takes the sensitivity to the same level achieved in the analysis of high PA analytes. Copyright © 2004 John Wiley & Sons, Ltd.
Enhanced responses in matrix‐assisted laser desorption/ionization mass spectrometry of peptides derivatized with arginine via a C‐terminal oxazolone
Authors: Nakazawa Takashi , Yamaguchi Minoru , Nishida Kimiko , Kuyama Hiroki , Obama Takashi , Ando Eiji , Okamura Taka‐aki , Ueyama Norikazu , Tanaka Koichi , Norioka Shigemi
Published: March 2004

We have developed a novel method for enhancing the response of a peptide in matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS) by activating the C‐terminal carboxyl group through an oxazolone with which is coupled an amine containing a functional group to help ionize the peptide. The reactions consist of dehydration with acetic anhydride to give an oxazolone, followed by aminolysis with an appropriate amino acid derivative such as arginine methyl ester. The MALDI signal of Ac‐Tyr‐Gly‐Gly‐Phe‐Leu‐Arg‐OMe, thus converted from leucine‐enkephalin, was detected while completely excluding the responses of arginine‐deficient peptides coexisting in the reaction mixture. Some less intense peaks corresponding to a few sequential degradation products, also terminated with the arginine derivative, were also observed. The side‐chain groups potentially that are reactive were conveniently protected by acetylation simultaneous with the C‐terminal activation, and those that remained unprotected were reduced to virtually negligible proportions when the reaction was conducted in a peptide solution of concentration less than 1 mM. The greatly increased responses of such arginine‐terminated peptides could possibly be exploited to discern the C‐terminal tryptic peptide of a protein that is otherwise almost insensitive to MALDI‐MS in general. The simplicity of the post‐source decay spectrum of enkephalin derivatized by arginine methyl ester characteristically accentuated z‐ and b‐type ions, and this should facilitate sequencing of such derivatized peptides. Remaining problems with practical applications of this approach are discussed. Copyright © 2004 John Wiley & Sons, Ltd.
Output feedback excitation control of synchronous generators
Authors: Maya‐Ortiz Paul , Espinosa‐Pérez Gerardo
Published: March 2004

In this paper a solution to the output feedback control problem, that improves the transient stability properties, of a single machine infinite bus power system is proposed by designing a nonlinear observer that asymptotically recovers the unmeasurable states of the system. The structure of the closed‐loop system is completed by considering an injection and damping assignment passivity‐based controller for which its stability properties are well established under a state feedback setting. It is shown, by using Lyapunov arguments and as a consequence of the asymptotic stability properties of the closed‐loop system, that the properties of the original state feedback controller are (also asymptotically) recovered. The output feedback design considers that both the load angle and the speed deviation of the machine are measurable and that the mechanical power delivered to the synchronous generator is constant and known, assumptions that allow to treat uncertainty on the operating (equilibrium) point of the system in a simple way. The theoretical results are illustrated via numerical simulations. Copyright © 2004 John Wiley & Sons, Ltd.
On the Validation of SPDM Task Verification Facility
Authors: Ma Ou , Wang Jiegao , Misra Sarthak , Liu Michael
Published: March 2004

This paper describes a methodology for validating a ground‐based, hardware‐in‐the‐loop, space‐robot simulation facility. This facility, called “SPDM task verification facility,” is being developed by the Canadian Space Agency for the purpose of verifying the contact dynamics performance of the special purpose dexterous manipulator (SPDM) performing various maintenance tasks on the International Space Station because the real SPDM cannot be physically tested for 3D operations on the ground due to the gravity. The facility uses a high‐fidelity SPDM mathematical model, known as the “truth model” of the space robot, to drive a hydraulic robot to mimic the space robot performing contact operations. In this research different techniques were studied for practically verifying that the complex simulation facility preserves the dynamics of the truth model of the space robot for space‐representative contact robotic tasks. Based upon the study and many years of experience in developing and verifying space robotic systems, a practical validation strategy including detailed test cases was developed along with a set of quantitative criteria for judging the validation test results. © 2004 Wiley Periodicals, Inc.
3D Cable‐Based Cartesian Metrology System
Authors: Williams Robert L. , Albus James S. , Bostelman Roger V.
Published: March 2004

A novel cable‐based metrology system is presented wherein six cables are connected in parallel from ground‐mounted string pots to the moving object or tool of interest. Cartesian pose can be determined for feedback control and other purposes by reading the lengths of the six cables via the string pots and using closed‐form forward pose kinematics. This article focuses on a sculpting metrology tool, assisting a human artist in generating a piece from a computer model, but applications exist in manufacturing, rapid prototyping, robotics, and automated construction. We present experimental data to demonstrate the operation of our system, we study the absolute accuracy and also measurement resolution, and we discuss various error sources. The proposed real‐time cable‐based metrology system is less complex and more economical than existing commercial Cartesian metrology technologies. © 2004 Wiley Periodicals, Inc.
The Synthesis of Three‐Degree‐of‐Freedom Planar Parallel Mechanisms with Revolute Joints (3‐RRR) for an Optimal Singularity‐Free Workspace
Authors: Arsenault Marc , Boudreau Roger
Published: March 2004

In this paper, a method is presented for the synthesis of 3‐RRR planar parallel mechanisms. The method uses a genetic algorithm while considering three different design criteria: the optimization of the mechanism workspace to approach a prescribed workspace, the maximization of the mechanism's dexterity, and the avoidance of singularities inside the mechanism workspace. It is shown that, for a given mechanism, some working modes do not have any corresponding singularity curves located inside the mechanism workspace. Furthermore, a case is presented where, for a given orientation range of the mechanism's end‐effector, there are no parallel singularities located inside the workspace. Finally, two methods are described and compared to deal with the nonuniform units of the mechanism's Jacobian matrix during the dexterity computation. © 2004 Wiley Periodicals, Inc.
Scanning force microscopy and amplitude versus distance measurements on single‐crystal oxide surfaces
Authors: Datar Suwarna , Patil Shivprasad , Iyyer S. B. , Dharmadhikari C. V.
Published: March 2004

Dynamic mode imaging and investigations on amplitude versus distance measurements were carried out on surfaces of single‐crystal; SrTiO3, Al2O3 and LaAlO3. Experiments were performed to optimize the imaging parameters for surfaces having varying elastic properties. The dependence of the amplitude–distance curve on different materials and the amplitude of oscillation was investigated. For SrTiO3, a low‐drive amplitude provided the linear region necessary for imaging. A large amplitude of oscillation, however, created dips in the amplitude–distance curves, presumably due to complications in the tip dynamics such as bifurcation, period doubling, etc. In the case of Al2O3 and LaAlO3, amplitude–distance curves were characterized by oscillations for lower tip sample separations and step‐like discontinuities in the stiff region. The magnitude of the oscillations and discontinuities was found to decrease with amplitude and eventually could be eliminated. Thus, for these samples a large amplitude of the cantilever provided the linear region required for imaging. It was observed also that two different surfaces of Al2O3 (c‐cut and r‐cut) yield totally different amplitude–distance curves consistent with their standard differences. The results indicate the complex behaviour of amplitude–distance curves, which not only vary from one sample to another but from one surface to another for a given sample. Copyright © 2004 John Wiley & Sons, Ltd.
Report on the 34th IUVSTA workshop ‘XPS: From Spectra to Results—Towards an Expert System’
Authors: Castle J. E. , Powell C. J.
Published: March 2004

A summary is given of the workshop entitled ‘XPS: From Spectra to Results–Towards an Expert System’ that was held in St. Malo, France, on 22–26 April 2002 under the sponsorship of the International Union of Vacuum Science, Technique and Applications (IUVSTA). This workshop was held to develop the structure and initial content of a possible future expert system for XPS. Following three plenary presentations, the participants met in six groups to discuss the following topics: instrument and specimen characterization; experimental objectives; wide‐scan interpretation–trial composition and structure; protocols for narrow scans, instrument set‐up and data acquisition; reduction of narrow‐scan data–chemical‐state and morphology analysis; and reduction of narrow‐scan data–quantification. These discussions led to many recommendations for elements of an expert system for XPS. Some of these recommendations are included in this summary but additional recommendations are included in the reports of the six groups available on the internet (http://www.iuvsta.org/W34.html). Copyright © 2004 John Wiley & Sons, Ltd.
Extremely low sputtering degradation of polytetrafluoroethylene by C60 ion beam applied in XPS analysis
Authors: Sanada N. , Yamamoto A. , Oiwa R. , Ohashi Y.
Published: March 2004

We have applied sputtering using a buckminsterfullerene (C60) ion beam for XPS analysis. A practical sputter rate of 2.4 nm min−1 for SiO2 was obtained for sputtering an area of 5 mm × 5 mm using a 5 kV C60 ion beam with an energy of 83 eV per carbon atom. Extremely low sputtering degradation of polytetrafluoroethylene was observed in these conditions. The results were compared with argon ion beam energies of 500 V and 5 kV. These are the first results utilizing a C60 ion beam for XPS analysis with limited sputtering damage. Copyright © 2004 John Wiley & Sons, Ltd.
Subnanometre depth resolution in sputter depth profiling of Si layers using grazing‐incident low‐energy O2+ and Ar+ ions
Authors: Lee Hyung‐Ik , Kim Hyun Kyong , Kim Kyung Joong , Moon Dae Won , Shon Hyun Kyung , Shin Hye Chung , Kang Hee Jae
Published: March 2004

The sputter damage profiles of Si(100) by low‐energy O2+ and Ar+ ion bombardment at various angles of incidence were measured using medium‐energy ion scattering spectroscopy. It was observed that the damaged Si surface layer can be minimized down to 0.5–0.6 nm with grazing‐incident 500 eV Ar+ and O2+ ions at 80°. To illustrate how the damaged layer thickness can be decreased down to 0.5 nm, molecular dynamics simulations were used. The SIMS depth resolution estimated with trailing‐edge decay length for a Ga delta‐layer in Si with grazing‐incident 650 eV O2+ was 0.9 nm, which is in good agreement with the measured damaged layer thickness. Copyright © 2004 John Wiley & Sons, Ltd.
Interpretation of static secondary ion spectra
Authors: Spool A. M.
Published: March 2004

A model is presented in which electron impact (EI)/electronic excitation plays a pivotal role in the formation of secondary ions in the SIMS experiment, especially those originating from discrete molecular species. Positive ions are formed by electron loss whereas negative ions are formed by electron capture. Collisions of the new ions with the surface and with other species directly above the sample, along with metastable decay events, reduce the number of odd electron ions detected and produce the changes that make SIMS spectra so different from EI mass spectra. Primary support for this model is gathered from static SIMS spectra themselves, which can be rationalized to a large degree by assuming that the same rearrangement and fragmentation mechanisms that are invoked to explain EI mass spectra take place at the surface after kiloelectron‐volt ion impacts. The static secondary ion spectra of a variety of simple discrete molecular species, of simple hydrocarbons, of monofunctional organic species and of more complicated multifunctional organic species are analyzed in this way and the utility of this model is demonstrated. Copyright © 2004 John Wiley & Sons, Ltd.
An interactive method for extracting grammar from programs
Authors: Jain Rahul , Aggarwal Sanjeev Kumar , Jalote Pankaj , Biswas Shiladitya
Published: March 2004

The grammar of the language in which some given code is written is essential for developing automated tools for maintenance, reengineering, and program analysis. Frequently grammar is available for a language but not for its variants that are implemented by various vendors and in which the given code may be written. In this work we address the problem of obtaining the grammar from source code, which can then be used for generating tools for the programs. We propose an incremental method for obtaining grammar for a particular language variant, from a set of programs written in the language variant and an approximate grammar (presumably of the standard language) with some user interaction. We also present the design of a tool for implementing this approach and our experience in working with grammars of C, C++ and COBOL. Copyright © 2004 John Wiley & Sons, Ltd.
Microbenchmarks for determining branch predictor organization
Authors: Milenkovic Milena , Milenkovic Aleksandar , Kulick Jeffrey
Published: March 2004

In order to achieve an optimum performance of a given application on a given computer platform, a program developer or compiler must be aware of computer architecture parameters, including those related to branch predictors. Although dynamic branch predictors are designed with the aim of automatically adapting to changes in branch behavior during program execution, code optimizations based on the information about predictor structure can greatly increase overall program performance. Yet, exact predictor implementations are seldom made public, even though processor manuals provide valuable optimization tips.

This paper presents an experimental flow with a series of microbenchmarks that determine the organization and size of a branch predictor using on‐chip performance monitoring registers. Such knowledge can be used either for manual code optimization or for design of new, more architecture‐aware compilers. Three examples illustrate how insight into exact branch predictor organization can be directly applied to code optimization. The proposed experimental flow is illustrated with microbenchmarks tuned for Intel Pentium III and Pentium 4 processors, although they can easily be adapted for other architectures. The described approach can also be used during processor design for performance evaluation of various branch predictor organizations and for testing and validation during implementation. Copyright © 2004 John Wiley & Sons, Ltd.
Agents in object‐oriented software engineering
Authors: Garcia Alessandro F. , de Lucena Carlos J. P. , Cowan Donald D.
Published: March 2004

Software engineers of multi‐agent systems (MASs) are faced with different concerns such as autonomy, adaptation, interaction, collaboration, learning, and mobility, which are essentially different from classical concerns addressed in object‐oriented software engineering. MAS developers, however, have relied mostly on object‐oriented design techniques and programming languages, such as Java. This often leads to a poor separation of MAS concerns and in turn to the production of MASs that are difficult to maintain and reuse. This paper discusses software engineering approaches for MASs, and presents a new method for integrating agents into object‐oriented software engineering from an early stage of design. The proposed approach encourages the separate handling of MAS concerns, and provides a disciplined scheme for their composition. Our proposal explores the benefits of aspect‐oriented software development for the incorporation of agents into object‐oriented systems. We also illustrate our aspect‐oriented approach through the Portalware multi‐agent system, a Web‐based environment for the development of e‐commerce portals. Copyright © 2004 John Wiley & Sons, Ltd.
In vivo vulnerability to competition by endogenous dopamine: Comparison of the D2 receptor agonist radiotracer (–)‐N‐[11C]propyl‐norapomorphine ([11C]NPA) with the D2 receptor antagonist radiotracer [11C]‐raclopride
Authors: Narendran Rajesh , Hwang Dah‐Ren , Slifstein Mark , Talbot Peter S. , Erritzoe David , Huang Yiyun , Cooper Thomas B. , Martinez Diana , Kegeles Lawrence S. , Abi‐Dargham Anissa , Laruelle Marc
Published: March 2004

(–)‐N‐Propyl‐norapomorphine (NPA) is a full dopamine (DA) D2 receptor agonist and [11C]NPA is a suitable radiotracer to image D2 receptors configured in a state of high affinity for agonists with positron emission tomography (PET). In this study the vulnerability of the in vivo binding of [11C]NPA to acute fluctuation in synaptic DA was assessed with PET in baboons and compared to that of the reference D2 receptor antagonist radiotracer [11C]raclopride. Three male baboons were studied with [11C]raclopride and [11C]NPA under baseline conditions and following administration of the potent DA releaser amphetamine (0.3, 0.5, and 1.0 mg kg–1 i.v.). Kinetic modeling with an arterial input function was used to derive the striatal specific‐to‐nonspecific equilibrium partition coefficient (V3″). [11C]Raclopride V3″ was reduced by 24 ± 10%, 32 ± 6%, and 44 ± 9% following amphetamine doses of 0.3, 0.5, and 1.0 mg kg–1, respectively. [11C]NPA V3″ was reduced by 32 ± 2%, 45 ± 3%, and 53 ± 9% following amphetamine doses of 0.3, 0.5, and 1.0 mg kg–1, respectively. Thus, endogenous DA was more effective at competing with [11C]NPA binding compared to [11C]raclopride binding, a finding consistent with the pharmacology of these tracers (agonist vs. antagonist). These results also suggest that 71% of D2 receptors are configured in a state of high affinity for agonists in vivo. In conclusion, [11C]NPA might provide a superior radiotracer to probe presynaptic DA function with PET in health and disease. Synapse 52:188–208, 2004. © 2004 Wiley‐Liss, Inc.
Locomotor sensitization to cocaine in rats with olfactory bulbectomy
Authors: Chambers R. Andrew , Sheehan Teige , Taylor Jane R.
Published: March 2004

Olfactory bulbectomy in rats has been suggested as a comprehensive animal model of affective disorders associated with an array of behavioral changes, responsivity to chronic antidepressant treatment, and alterations in limbic structures thought to be critical in the pathophysiology of affective disorders. Recent work showing increased motivational responsivity to amphetamine suggests that olfactory bulbectomy could also be a useful animal model of dual diagnosis disorders. To further investigate this possibility, we studied locomotor activity in olfactory bulbectomized rats 14 days postsurgery in response to novelty and upon acute and repeated injections of cocaine (15/mg/kg) or saline. Consistent with prior studies, lesioned animals showed greater locomotor activity in response to a novel environment and significantly heightened locomotor activation upon initial cocaine exposure. Over 7 days of repeated cocaine injections, lesioned animals also showed a presensitized pattern of activity, with a loss of incremental increases in locomotion observed in control animals. Daily saline injections produced no group differences in pre‐ or postinjection activity, while cocaine‐treated bulbectomized rats demonstrated a decline in their daily preinjection activity. These results suggest that neural alterations caused by olfactory bulbectomy produce altered behavioral response patterns to repeated doses of cocaine, and support the study of olfactory bulbectomy as a useful neurobehavioral model for understanding substance use disorder comorbidity in mental illness. Synapse 52:167–175, 2004. © 2004 Wiley‐Liss, Inc.
Opioid peptide receptor studies. 17. Attenuation of chronic morphine effects after antisense oligodeoxynucleotide knock‐down of RGS9 protein in cells expressing the cloned Mu opioid receptor
Authors: Xu Heng , Wang Xiaoying , Wang Jun , Rothman Richard B.
Published: March 2004

RGS proteins are a recently described class of regulators that influence G‐protein‐mediated signaling pathways. We have shown previously that chronic morphine results in functional uncoupling of the μ opioid receptor from its G protein in CHO cells expressing cloned human μ opioid receptors. In the present study, we examined the effects of morphine treatment (1 μM, 20 h) on DAMGO‐stimulated high‐affinity [35S]GTP‐γ‐S binding and DAMGO‐mediated inhibition of forskolin‐stimulated cAMP accumulation in HN9.10 cells stably expressing the cloned rat μ opioid receptor, in the absence and presence of the RGS9 protein knock‐down condition (confirmed by Western blot analysis). RGS9 protein expression was reduced by blocking its mRNA with an antisense oligodeoxynucleotide (AS‐114). Binding surface analysis resolved two [35S]GTP‐γ‐S binding sites (high affinity and low affinity sites). In sense‐treated control cells, DAMGO‐stimulated [35S]GTP‐γ‐S binding by increasing the Bmax of the high‐affinity site. In sense‐treated morphine‐treated cells, DAMGO‐stimulated [35S]GTP‐γ‐S binding by decreasing the high‐affinity Kd without changing the Bmax. AS‐114 significantly inhibited chronic morphine‐induced upregulation of adenylate cyclase activity and partially reversed chronic morphine effects as measured by DAMGO‐stimulated [35S]GTP‐γ‐S binding. Morphine treatment increased the EC50 (6.2‐fold) for DAMGO‐mediated inhibition of forskolin‐stimulated cAMP activity in control cells but not in cells treated with AS‐114 to knock‐down RGS9. These results provide additional evidence for involvement of RGS9 protein in modulating opioid signaling, which may contribute to the development of morphine tolerance and dependence. Synapse 52:209–217, 2004. Published 2004 Wiley‐Liss, Inc.
Intraobserver and interobserver variation in the sonographic grading of placental maturity
Authors: Sau A. , Seed P. , Langford K.
Published: March 2004

Objectives

The appearance of Grannum Grade III changes in the placenta at around 34–36 weeks is a predictor of adverse perinatal outcome, which may be reduced by reporting to the clinician. This has led to the suggestion that the placental grade should be noted during any third‐trimester scan. There are no published data on the reproducibility of sonographic Grannum grading of the placenta; the objective of this study was to evaluate intra‐ and interobserver variation.

Methods

Fifty‐five placental images from normal and complicated pregnancies of several different gestational ages were collected between April and October 2001. Three fetal medicine consultants and three experienced sonographers graded the images as 0, I, II, III or ungradeable. They then regraded the same images, presented in a different order and with different codes, 4–6 weeks later. Observers were blinded to their previous grading and to each others'. Weighted kappa (κ), with linear weights, was used to look for strength of agreement.

Results

There was good agreement between the two observations of each placental image for five observers (κ = 0.61 to 0.90), and moderate agreement for one observer (κ = 0.56). However, the κ‐values for comparisons between the 15 pairs of observers ranged from 0.24 to 0.69 with six values below 0.41, indicating only fair agreement. This was confirmed by the overall κ‐value of 0.24 between all six observers. The agreement between the observers for Grade III placenta was poor, with an overall κ‐value of 0.09.

Conclusions

Although intraobserver agreement was generally good, interobserver agreement was only fair for all grades and poor for Grade III placenta. This may be an indication that Grannum grading is not reproducible or it may reflect a need for training in those performing grading. Such variation may limit the effectiveness of reporting Grannum grades in clinical practice. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Successful intrauterine treatment with radiofrequency ablation in a case of acardiac twin pregnancy complicated with a hydropic pump twin
Authors: Hirose M. , Murata A. , Kita N. , Aotani H. , Takebayashi K. , Noda Y.
Published: March 2004

Twin reversed arterial perfusion sequence is a serious complication of monochorionic twin pregnancy, as the pump twin that perfuses blood to the acardiac twin may experience heart failure and fetal hydrops resulting in a poor perinatal outcome. A woman with an acardiac twin pregnancy complicated by a hydropic pump twin underwent intrauterine treatment with radiofrequency ablation (RFA) at 27 weeks of gestation. Obliteration of blood flow to the acardiac twin from the pump twin was successful. Fetal hydrops resolved by the time of delivery at 32 weeks of gestation, in spite of transient deterioration, and a good postnatal outcome was achieved for the pump twin. We found that RFA was an effective intrauterine treatment for acardiac twin pregnancy and suggest that it could be introduced in cases complicated by a hydropic pump twin. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Sonographic detection of fluid collections and postoperative morbidity following Cesarean section and hysterectomy
Authors: Antonelli E. , Morales M. A. , Dumps P. , Boulvain M. , Weil A.
Published: March 2004

Objectives

To evaluate the clinical significance of sonographically detected fluid collections following Cesarean section and hysterectomy, and to identify risk factors associated with their formation.

Methods

This was a prospective study including 280 women, 145 of whom had undergone a Cesarean section and 135 of whom had undergone abdominal or vaginal hysterectomy. Ultrasound examinations were carried out on all women on day 4 after surgery to assess the presence of abdominal wall or pelvic fluid collections. The sonographers were unaware of the clinical course before the examination and were not involved in any clinical decision‐making. Ultrasound findings were correlated with clinical data and postoperative morbidity.

Results

A fluid collection was found in 69 (48%) women after Cesarean section, and in 59 (44%) women who had undergone hysterectomy. No risk factors for the development of fluid collections after Cesarean section or hysterectomy were identified. The risk of developing febrile morbidity was not related to the presence, location or size of fluid collections.

Conclusions

Postoperative fluid collections are common after Cesarean section and hysterectomy. As fluid collections detected by sonography were not associated with postoperative morbidity, this finding is unlikely to be useful in the workup for postoperative fever. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Umbilical cord serum vascular endothelial growth factor (VEGF) levels in normal pregnancies and in pregnancies complicated by preterm delivery or pre‐eclampsia
Authors: Galazios G. , Papazoglou D. , Giagloglou K. , Vassaras G. , Koutlaki N. , Maltezos E.
Published: March 2004

Objectives: The aim of this study was to determine whether increased levels of vascular endothelial growth factor (VEGF) are implicated in the pathogenesis of pre‐eclampsia and in preterm delivery. Methods: Umbilical cord serum VEGF levels from women with uncomplicated term pregnancies (control group, n=24), with pregnancies complicated by pre‐eclampsia (n=21), or with preterm delivery (n=29) were compared. Statistical analysis was performed using the Mann–Whitney U‐test, the t‐test, and Smirnoff–Kolmogorov test. Results: The mean VEGF concentration was significantly higher in the women with pre‐eclampsia than in women from the control group (P<0.01). There were also increased but not significantly higher VEGF concentrations in the preterm delivery group compared with the control group (P=0.16). Conclusions: Our study results support previous findings that raised umbilical cord serum VEGF levels might be correlated with the clinical development of pre‐eclampsia and, in some circumstances, of preterm delivery.
Balloon mitral valvuloplasty during pregnancy
Authors: Routray S.N. , Mishra T.K. , Swain S. , Patnaik U.K. , Behera M.
Published: March 2004

Objectives: Balloon mitral valvuloplasty (BMV) has been performed safely during pregnancy with good results. Reports are few on long‐term effects of BMV on childhood development. Methods: BMV was performed in 40 pregnant women (age 23.4±4.8 years) with severe mitral stenosis at 24.2±4.6 weeks of gestation. Results: Mitral valve area increased from 0.82±0.34 to 1.9±0.4 cm2 (P<0.001). One patient had pericardial tamponade. Mean fluoroscopy time was 5.5±3.8 min. There was no maternal death, no abortion, no intrauterine growth restriction and one stillbirth. All 39 babies were normal at birth. One baby died at 7 months due to pneumonia. On follow up for 36±15 months, all 38 babies maintained normal growth and development without any thyroid disease or malignancy. Conclusions: During pregnancy BMV is feasible, safe and effective. Maternal and fetal outcomes are excellent. Growth and milestone of development are not affected.
The effects of lumbosacral orthoses on spine stability: What changes in EMG can be expected?
Authors: Cholewicki Jacek
Published: March 2004

Antagonistic trunk muscle activity is normally required to stabilize the spine. A lumbosacral orthosis (LSO) might reduce the need for this antagonistic activity by providing passive stiffness to the trunk and increasing spine stability. The maximum reduction in trunk muscle EMG and in the resultant spine compression force due to the LSO was estimated using a biomechanical model. The lumbar spine stability was first quantified for the average trunk muscle EMG recorded from 11 male subjects performing various isometric trunk exertion tasks. Subsequently, the spine‐stiffening effects of the LSO were implemented in the model and trunk muscle forces were reduced iteratively until the original level of spine stability without the LSO was achieved. The upper bound estimates of the reduction in trunk muscle EMG due to LSO ranged from 0.6% to 14.1% of the maximum voluntary activation depending on the task and the muscle. The resultant spine compression force averaged across all tasks decreased by only 355 N. A much larger variance of the experimental data precluded the detection of these effects at statistically significant levels. However, the small effects size does not necessarily exclude the possibility of functional benefits of slightly reducing muscle activity in patients with low back pain. © 2004 Orthopaedic Research Society. Published y Elsevier Ltd. All rights reserved.
Multiple feedback loops are key to a robust dynamic performance of tryptophan regulation in Escherichia coli
Authors: Venkatesh K.V. , Bhartiya Sharad , Ruhela Anurag
Published: March 2004

Living systems must adapt quickly and stably to uncertain environments. A common theme in cellular regulation is the presence of multiple feedback loops in the network. An example of such a feedback structure is regulation of tryptophan concentration in Escherichia coli. Here, three distinct feedback mechanisms, namely genetic regulation, mRNA attenuation and enzyme inhibition, regulate tryptophan synthesis. A pertinent question is whether such multiple feedback loops are “a case of regulatory overkill, or do these different feedback regulators have distinct functions?” [Freeman (2000) Nature 295, 313–319]. Another moot question is how robustness to uncertainties can be achieved structurally through biological interactions. Correlation between the feedback structure and robustness can be systematically studied by tools commonly employed in feedback theory. An analysis of feedback strategies in the tryptophan system in E. coli reveals that the network complexity arising due to the distributed feedback structure is responsible for the rapid and stable response observed even in the presence of system uncertainties.
Primary Renal Tumours in Cats: 19 Cases (1992–1998)
Authors: Henry C J , Turnquist S E , Smith A , Graham J C , Thamm D H , O'Brien M , Clifford C A
Published: March 2004

A search from databases of four veterinary colleges and one private referral practice between January 1992 and April 1998 provided 20 cases diagnosed with primary renal neoplasia. Review of these cases revealed 19 primary renal tumours, excluding lymphoma. Of the 20 histologically reviewed cases, the diagnosis was amended in eight. There were 13 renal carcinomas (11 tubular and two tubulopapillary), three transitional cell carcinomas, one malignant nephroblastoma, one haemangiosarcoma and one adenoma. The haemangiosarcoma is, to our knowledge, the first reported case of this tumour type as a primary renal tumour in the cat. Most cats were presented for non-specific clinical signs such as anorexia and weight loss. One cat presented with tumour-associated polycythaemia which has not, to our knowledge, been reported previously. The metastatic rate for cats with complete staging was 64%, and 100% for transitional cell carcinomas.
Recommendations for the Housing of Cats in the Home, in Catteries and Animal Shelters, in Laboratories and in Veterinary Surgeries
Authors: Rochlitz I
Published: March 2004

In recent years, there has been an increase in interest in applied ethology and animal welfare, and an increase in the popularity of the domestic cat. This has stimulated research on the behaviour and welfare of cats kept in different environments. This article presents a review of the recent research and makes recommendations for the housing of domestic cats in the home, in catteries and animal shelters, in laboratories and in veterinary surgeries.
Comparisons of polarization switching in “hard,” “soft,” and relaxor ferroelectrics
Authors: Jullian Christelle , Li J. F. , Viehland D.
Published: March 2004

The dynamics of polarization switching have been investigated over extremely broad time (10−8<t<102 s) and field ranges for hard, soft, and relaxor ferroelectrics based on aliovalent modified Pb(Zr1−xTix)O3. The results unambiguously demonstrate important differences in the polarization switching mechanism for these various types of ferroelectrics.
Electron capture by quantum wells in an internal electric field
Authors: Villegas-Lelovsky L. , González de la Cruz G.
Published: March 2004

We have investigated the electron capture times by a single quantum well, taking into account the influence of the built-in electric field due to the piezoelectric effect as in GaN/AlxGa1−xN and GaAs/InxGa1−xN structures. Theoretical carrier capture is calculated by considering a variational electron wave function inside the quantum well and a linear combination of the Airy functions above the quantum well. It is shown that the scattering rate by the optical-phonon deformation potential exhibits a smoothly decreasing function with increasing electric field. This effect is due to the shift of the bound state to lower energies and to the electron heating due to the electric field in the quantum well. This result is quantitatively in agreement with both Monte Carlo simulations and previous experimental measurements.
Boron segregation and electrical properties in polycrystalline Si1−x−yGexCy and Si1−yCy alloys
Authors: Stewart E. J. , Carroll M. S. , Sturm J. C.
Published: March 2004

In this article, we report strong boron segregation to polycrystalline Si1−x−yGexCy from polysilicon during thermal anneals in the temperature range of 800–900 °C. This effect is larger than previous reports of segregation to single-crystal Si1−xGex and increases with carbon concentration. Segregation also occurs in polycrystalline Si1−yCy, revealing that carbon by itself can drive the segregation (without germanium present). This segregation is used to model the enhanced threshold voltage stability of p-channel metal oxide semiconductor field effect transistors with boron-doped polycrystalline Si1−x−yGexCy gates. We also study the electrical properties of polycrystalline Si1−x−yGexCy. For low carbon concentrations (0.4%), polycrystalline Si1−x−yGexCy has a similar level of dopant activation and mobility as polycrystalline Si1−xGex; increasing the concentration to 1.6% results in significant losses in both. Annealing the films for time scales similar to those needed for segregation causes no degradation of the electrical properties, indicating that electrically inactive defects are not driving the segregation.
Study of polarization-dependent energy coupling between near-field optical probe and mesoscopic metal structure
Authors: Gademann A. , Shvets I. V. , Durkan C.
Published: March 2004

We present an experimental study of the coupling of light from a probe of a scanning near-field optical microscope (SNOM) into a mesoscopic structure consisting of gold stripes with varying separations. We demonstrate that the coupling efficiency depends upon the polarization direction in the probe relative to the stripes as well as the separation between the lines. Two possible explanations for a contrast reversal effect in between s- and p-polarized light are given. One is based on the excitation of a quasi-transverse electric and magnetic mode in the mesoscopic transmission line. For this explanation we have made a prediction of the condition of the maximum coupling efficiency through the approach of impedance matching. The second explanation is based on surface plasmon excitation in the gold structure. The present results can also be of importance in the development of new concepts of probes for SNOM.