bluuebunny/crossref_metadata_2025 huggingface dataset:
A low-noise and wide-band ac boosting current-to-voltage amplifier for scanning tunneling microscopy
Authors: Kim Dae-Jeong , Koo Ja-Yong
Published: January 2005

A compact, fast, and low-noise current-to-voltage amplifier is built for scanning tunneling microscopy. The amplifier consists of two amplification stages. The first stage performs low-noise transimpedance amplification by using a high performance FET operational amplifier together with a high-ohm feedback resistor of 1GΩ and a parallel trimming capacitor. The ac boosting amplifier in the second stage recovers the higher frequency above the 3dB cutoff of the first stage to extend the maximum bandwidth up to 100kHz. This two-stage current-to-voltage amplifier shows a low current noise below sub-pA rms when tuned to have the bandwidth of around 1kHz. It also guarantees stable frequency response in the presence of 1000pF input capacitance.
High resolution kinetic energy by long time-delayed core-sampling photofragment translational spectroscopy
Authors: Li Guosheng , Hwang Hyun Jin , Jung Hyun Chai
Published: January 2005

A pulsed core-sampling photofragment translational spectroscopy (PTS) method with a long time-delay, which allows an extremely high kinetic energy resolution, is presented in this article. More commonly applying a short time delay between laser and pulsed acceleration electric field leads to a low kinetic energy resolution for the pulsed core-sampling method. This low kinetic energy resolution problem was overcome by applying a longer time delay. An absolute recoil velocity resolution of Δv=8m∕s and a relative kinetic energy resolution of ΔE∕E=3.6% were obtained in this experiment, by applying a time-delay of 8μs between the laser and the acceleration electric field. The vibrational distributions of the CH3 radical for the I* and I channel of CH3I photodissociation at 266nm were directly resolved for first time to presented an improvement of the kinetic energy resolution.
Polarization-dependent Raman spectra of thin crystalline silicon films
Authors: Lu Z. Q. , Quinn T. , Reehal H. S.
Published: January 2005

Polarization-dependent Raman spectra are presented to analyze the structural properties of epitaxial, quasiepitaxial, and microcrystalline silicon films deposited on (100) single-crystal silicon substrates by electron cyclotron resonance plasma-enhanced chemical-vapor deposition. We rotate the sample with respect to the polarization direction of the incident laser light and observe the changes in Raman scattering. The measurements are very effective in differentiating between films with a preferred orientation and those that are randomly oriented or amorphous. An interesting anisotropy has been observed for quasiepitaxial films for which the spectra resemble those of single-crystal wafers under normal measurement conditions. However, at sample orientations where the scattering intensity is minimized, additional structure on the low-energy side of the main silicon TO-phonon peak becomes visible. This is tentatively attributed to scattering from crystalline and amorphouslike grain-boundary regions. Polarization-dependent Raman spectra are able to provide useful information on the structure of these films which would normally be masked by the main silicon optical-phonon peak.
Fluence, flux, and implantation temperature dependence of ion-implantation-induced defect production in 4H–SiC
Authors: Slotte J. , Saarinen K. , Janson M. S. , Hallén A. , Kuznetsov A. Yu. , Svensson B. G. , Wong-Leung J. , Jagadish C.
Published: January 2005

Vacancy-type defect production in Al- and Si-implanted 4H–SiC has been studied as a function of ion fluence, ion flux, and implantation temperature in the projected ion range region by positron annihilation spectroscopy and Rutherford backscattering techniques. Ion channeling measurements show that the concentration of displaced silicon atoms increases rapidly with increasing ion fluence. In the ion fluence interval of 1013–1014cm−2 the positron annihilation parameters are roughly constant at a defect level tentatively associated with the divacancy VCVSi. Above the ion fluence of 1014cm−2 larger vacancy clusters are formed. For implantations as a function of ion flux (cm−2s−1), ion channeling and positron annihilation measurements behave similarly, i.e., indicating increasing damage in the projected range region with increasing ion flux. However, for samples implanted at different temperatures the positron annihilation parameter S shows a clear minimum at approximately 100°C, whereas the normalized backscattering yield decrease continuously with increasing implantation temperature. This is explained by the formation of larger vacancy clusters when the implantation temperature is increased.
Transport and magnetic properties of La0.9Ce0.1MnO3 thin films
Authors: Yanagida Takeshi , Kanki Teruo , Vilquin Bertrand , Tanaka Hidekazu , Kawai Tomoji
Published: January 2005

The transport and magnetic properties of La0.9Ce0.1MnO3 epitaxial thin films without observable impurity of CeO2 on their x-ray diffraction data using pulsed laser deposition method were investigated by varying the oxygen partial pressure and the substrate temperature with the intention being to investigate whether the material is an electron-doped system. The film deposited under the oxygen partial pressure of 1Pa exhibited the metal-insulator transitionlike peak and ferromagnetic transition around 200K. Thermopower measurement identified the major carriers within the film to be holes. In addition, decreasing the oxygen partial pressure resulted in not only an increase in the resistivity but also a decrease in the Curie temperature. In fact, these trends on transport and magnetic properties are consistent with general trends of a hole-doped system.
Formation mechanism of alumina nanotubes and nanowires from highly ordered porous anodic alumina template
Authors: Mei Y. F. , Siu G. G. , Fu Ricky K. Y. , Chen P. , Wu X. L. , Hung T. F. , Chu Paul K. , Yang Y.
Published: January 2005

Alumina nanotube (ANT) and nanowire (ANW) arrays were produced from highly ordered porous anodic alumina (PAA) by etching in phosphoric acid and subsequent thermal treatment. The domain structures that have small sizes provide more boundaries and break the hexagonal symmetry of the PAA template, thereby inducing star-like splitting modes. Using very thin PAA films, ANTs and their arrays are fabricated, whereas ANWs and their arrays are produced when using thick films. This is due to the thin wall between nanopores. Our results provide some mechanistic and fundamental information pertaining to the fabrication of nanostructures via a PAA template.
Spin-current effect on ferromagnetic resonance in patterned magnetic thin film structures
Authors: Xi Haiwen , Shi Yiming , Gao Kai-Zhong
Published: January 2005

We have theoretically investigated the ferromagnetic resonance in the magnetic thin film structures under the influence of spin-transfer torque using a modified Landau–Lifshitz–Gilbert equation in the linearization regime. The study shows that spin currents do not shift the resonance field but rather change both the resonance amplitude and the linewidth. Ferromagnetic resonance under this circumstance can be characterized by an effective damping constant. Depending upon its direction, the spin current can pump energy into or dissipate energy from the magnetic system. In addition, the quality factor of the resonance can be tuned by changing the current intensity. Ferromagnetic resonance excited by ac electrical currents is also theoretically demonstrated and discussed in this article.
Ultrafast carrier dynamics in an InGaN thin film
Authors: Wang Hsiang-Chen , Lu Yen-Cheng , Teng Chih-Chung , Chen Yung-Sheng , Yang C. C. , Ma Kung-Jen , Pan Chang-Chi , Chyi Jen-Inn
Published: January 2005

We perform femtosecond degenerate pump-probe experiments on an InGaN thin film of 800 nm in thickness. The observed temperature-, pump-photon-energy-, and pump-intensity-dependent variations of ultrafast carrier dynamics manifest the variation of the space-averaged density of state with energy level in this sample. The carrier dynamics is controlled by the shift of effective band gap and hence the behavior of band filling, which are determined by the combined effect of band-gap renormalization and phonon effect (band-gap shrinkage with increasing temperature). Two-photon absorption and free-carrier absorption can be observed when the corresponding density of state is low and hence the band-filling effect is weak. The variation of the space-averaged density of state with energy level can be due to the existence of indium-composition-fluctuation nanostructures, which is caused by the spinodal decomposition process, in the sample.
The influence of base bias on the collector photocurrent for InGaP∕GaAs heterojunction phototransistors
Authors: Tan S. W. , Chen H. R. , Chen W. T. , Hsu M. K. , Lin A. H. , Lour W. S.
Published: January 2005

Fabrication, characterization, and theoretical modeling of two-terminal and three-terminal heterojunction phototransistors ( 2T- and 3T-HPTs) based on InGaP∕GaAs are reported. For a current–bias 3T-HPT, an independent current flowing into or out of base electrode is employed to modulate the operating point of a heterojunction bipolar transistor (HBT). The operating point of a HBT in the presence of a positive bias current can be tuned to a higher current level where the current gain is larger. It is found that the optical gain increases from 28.4 for a 2T-HPT to 34 for a 3T-HPT with a bias current of 10μA. The achievement of tunability of the operating point of a HBT has also been attempted with an independent voltage source. Nevertheless, our work reveals that the p–i–n photocurrent generated within the B–C region contributes very little to the final collector photocurrent for a voltage–bias 3T-HPT, resulting in a rather small optical gain in the range 0.8–1.6. A simple equivalent circuit model is developed to explain the differences between a current– and a voltage–bias 3T-HPT. Our calculated results are in good agreement with the experimental ones.
Growth of N,N′-di(naphthalene-1-yl)-N,N′-diphenyl-benzidine dome structures
Authors: Leung Y. H. , Djurišić A. B. , Cheung C. H. , Xie M. H. , Chan W. K.
Published: January 2005

N , N ′ -di(naphthalene-1-yl)-N,N′-diphenyl-benzidine samples exhibiting interesting nano/microstructure were fabricated by thermal evaporation in a tube furnace under Ar gas flow. We investigated the influence of the substrate type, substrate temperature, source temperature, and the gas flow rate on the obtained morphology. The deposited material was investigated using scanning electron microscopy, x-ray diffraction, and photoluminescence. We found that the substrate temperature was the factor which significantly affected the obtained morphology, while other factors such as substrate type, source temperature, and gas flow mainly affected the size distribution of the features but not the type of morphology observed.
Identification of nitrogen chemical states in N-doped ZnO via x-ray photoelectron spectroscopy
Authors: Perkins Craig L. , Lee Se-Hee , Li Xiaonan , Asher Sally E. , Coutts Timothy J.
Published: January 2005

Nitrogen-doped films of ZnO grown by two methods, metalorganic chemical vapor deposition (MOCVD) and reactive sputtering, were studied with x-ray and ultraviolet photoelectron spectroscopy (XPS and UPS). Systematic differences in the N chemical states were observed between films grown by sputtering and MOCVD: only two N chemical states were observed in films grown by reactive sputtering, whereas four N chemical states were observed in MOCVD films. To aid in the assignment of the N chemical states, photoemission data from the polycrystalline films were compared with data taken on N2+-implanted Zn metal and N2+-implanted ZnO. High-resolution core level spectra of the N1s region indicated that nitrogen can occupy at least four different chemical environments in ZnO; these include the NO acceptor, the double donor (N2)O, and two carbon–nitrogen species. Valence band spectra indicate that the Fermi energy of all films studied was near the conduction band minimum, implying that the films remained n-type after nitrogen doping. Analysis of the relative amounts of acceptors and donors identified by XPS in the sputter-grown films provides clues as to why only a small percentage of incorporated nitrogen is found to contribute to carriers, and points toward possible paths to higher quality ZnO:N films.
Development of low field nuclear magnetic resonance microcoils
Authors: Goloshevsky A. G. , Walton J. H. , Shutov M. V. , de Ropp J. S. , Collins S. D. , McCarthy M. J.
Published: January 2005

A miniaturized spiral Helmholtz rf coil was fabricated using standard photolithography and electroplating. A commercial 0.6 T superconductive magnet was used to test the coil performance for both nuclear magnetic resonance (NMR) spectroscopy and imaging applications. NMR spectra of water, methanol, and 1-propanol were obtained as well as static and flow images of a water phantom. The spectral resolution was sufficient to allow chemical identification. Additionally, the viscosity of water was estimated from the experimental velocity profile and was equal to the expected value of 1 cP. Results obtained demonstrated the prospect of using the Helmholtz rf coil as part of a portable low-field NMR system for applications in analytical chemistry and process measurements in industrial settings.
Effect of grain size on the electrical properties of (Ba,Ca)(Zr,Ti)O3 relaxor ferroelectric ceramics
Authors: Tang Xin-Gui , Chan Helen Lai-Wah
Published: January 2005

( Ba 0.90 Ca 0.10 ) ( Zr 0.25 Ti 0.75 ) O 3 (BCZT) relaxor ferroelectric ceramics with grain sizes of 0.85, 2.5, 15, and 30μm were prepared from powders synthesized using a sol-gel process. The effects of grain size and dc field on the dielectric properties and tunabilities of BCZT ceramics were investigated. As the grain size decreased, the maximum dielectric constant decreased and the transition temperature increased. The BCZT ceramics with various grain sizes showed a typical relaxor ferroelectric behavior. The dielectric relaxation rate follows the Vogel–Fulcher relation. The dielectric constant is greatly suppressed and the low loss is obtained under a dc electric field. At room temperature (300K) and 20kV∕cm, the tunabilities and figures of merit are 42% and 62, 51% and 98, 56% and 193, and 51% and 182, respectively, for the BCZT ceramics with grain sizes of 0.85, 2.5, 15, and 30μm.
Quantum wires and dots induced in a semiconductor by charged metallic filaments separated by an isolating barrier
Authors: Gribnikov Z. S. , Haddad G. I.
Published: January 2005

A very thin positively charged metallic filament separated from a surface of a semiconductor (S) by a thin nontunneling potential barrier (B) induces a quantum wire (QWr) in the semiconductor at the B∕S interface. Single-electron quantum states of this QWr are controlled by a potential (and a charge) of the metallic filament. Two close parallel metallic filaments placed over such a B∕S interface form a double-quantum wire with the ground and the first excited electron states, which appear as a result of a symmetric–antisymmetric splitting of the ground electron state in the single QWr. Two crossed metallic filaments, which are parallel to the B∕S interface, form a quantum dot with completely localized electron states under the crossing point of the metallic filaments. The analogous crossing of a metallic filament by a pair of close metallic filaments forms a double-quantum dot (DQD). The latter can serve as a two-level qubit cell. Such qubits can be controlled by potentials of three independent metallic filaments inducing the above-mentioned DQD. Besides this “outside” metallic wire control, the DQDs can be connected to each other across the “inside” quantum wires, which have formed these DQDs by crossing.
The Deubiquitinating Enzyme Ubp1 Affects Sorting of the ATP-binding Cassette-Transporter Ste6 in the Endocytic Pathway
Authors: Schmitz Carolin , Kinner Andrea , Kölling Ralf
Published: January 2005

Deubiquitinating enzymes (Dubs) are potential regulators of ubiquitination-dependent processes. Here, we focus on a member of the yeast ubiquitin-specific processing protease (Ubp) family, the Ubp1 protein. We could show that Ubp1 exists in two forms: a longer membrane-anchored form (mUbp1) and a shorter soluble form (sUbp1) that seem to be independently expressed from the same gene. The membrane-associated mUbp1 variant could be localized to the endoplasmic reticulum (ER) membrane by sucrose density gradient centrifugation and by immunofluorescence microscopy. Overexpression of the soluble Ubp1 variant stabilizes the ATP-binding cassette-transporter Ste6, which is transported to the lysosome-like vacuole for degradation, and whose transport is regulated by ubiquitination. Ste6 stabilization was not the result of a general increase in deubiquitination activity, because overexpression of Ubp1 had no effect on the degradation of the ER-associated degradation substrate carboxypeptidase Y* and most importantly on Ste6 ubiquitination itself. Also, overexpression of another yeast Dub, Ubp3, had no effect on Ste6 turnover. This suggests that the Ubp1 target is a component of the protein transport machinery. On Ubp1 overexpression, Ste6 accumulates at the cell surface, which is consistent with a role of Ubp1 at the internalization step of endocytosis or with enhanced recycling to the cell surface from an internal compartment.
Marketing is not dead: a response to “Elegy on the death of marketing”
Authors: McCole Patrick
Published: January 2005

Discusses the death of marketing and provides evidence to the contrary that marketing is far from dead – or dying. Discusses the implications of the role of marketing both in the online and offline world. Accepts that marketing may be in need of realignment to reflect contemporary marketing practices.
The use of customer language in international marketing communication in the Scottish food and drink industry
Authors: Marcella Rita , Davies Sylvie
Published: January 2005

This paper reports the results of case studies of Scottish food and drink exporters which sought to explore the use of customer language in marketing and exporting products to France. The findings provide evidence for three levels of language orientation, illustrating differing attitudes to the impact of customer language use, despite consensus that such is good practice and “courteous” in responding to customers. Given the diverse import community, language is more influential in certain contexts and at certain points in the marketing process. Changes in the exporter/importer dynamic may indicate greater need for customer language skills amongst exporters, but this was regarded with mixed feelings by the case study companies. Trends such as the increased demand for product information and the growing reliance on electronic communication had an impact on language of communication, in particular with the shift to processed products. A number of paradigms of Internet usage are identified, with the more proactive companies employing a multi‐level, multilingual approach.
How “ready” are customers for mass customisation? An exploratory investigation
Authors: Bardakci Ahmet , Whitelock Jeryl
Published: January 2005

This paper examines the concept of mass customisation from the point of view of the customer. Although the theory of mass customisation has received considerable attention in recent years, the emphasis has been on identifying and classifying the ways in which mass customisation can be implemented efficiently and effectively. There appears to have been no empirical evidence to support the notion that customers are indeed ready for this approach. The aim of this study is to examine how far customers are “ready” for mass‐customised products, using the UK new car market as its basis for analysis. A framework is developed and results presented which suggest that a sizeable section of the market is ready to accept the “inconveniences” of mass‐customised products. However, the main inconvenience of mass customisation is identified as increased price, even for “ready” customers. It would seem, therefore, that both global standardisation and mass customisation strategies are appropriate in this market.
Retail sales explanations: resolving unsatisfactory sales encounters
Authors: Dunning Jarrad , O'Cass Aron , Pecotich Anthony
Published: January 2005

The general proposition that a salesperson's explanation adequacy plays a critical role in the resolution of unsatisfactory sales encounters for consumers is investigated in a cross‐sectional context. The findings indicate that explanation adequacy is influenced by both the style and content of the explanation, and the timeliness of an organization's reaction, whereas explanation adequacy only indirectly affects the final perceptions of the severity of the incident and emotional reaction to it. Importantly, the perceptions of the extent of the justice of the resolution and the assignment of blame to external factors were found to be intervening variables. The results also indicated that the assignment of blame to internal factors was unrelated to the adequacy of an explanation, but did influence emotion and the perceived severity on an incident.
Service quality and customer retention: building long‐term relationships
Authors: Venetis Karin A. , Ghauri Pervez N.
Published: January 2005

The study extends the existing knowledge by taking a relationship perspective to study the effect of service quality on customer retention. We integrate business‐to‐business marketing literature with service quality literature to develop a model to capture relationship commitment and other influencing factors. The model is improved with help of semi‐structured interviews which is later tested through a survey of 241 companies in the advertising sector. Findings indicate that service quality indeed contributes to the long‐term relationships and customer retention.
Descriptor‐based protein remote homology identification
Authors: Zhang Ziding , Kochhar Sunil , Grigorov Martin G.
Published: January 2005

Here, we report a novel protein sequence descriptor‐based remote homology identification method, able to infer fold relationships without the explicit knowledge of structure. In a first phase, we have individually benchmarked 13 different descriptor types in fold identification experiments in a highly diverse set of protein sequences. The relevant descriptors were related to the fold class membership by using simple similarity measures in the descriptor spaces, such as the cosine angle. Our results revealed that the three best‐performing sets of descriptors were the sequence‐alignment‐based descriptor using PSI‐BLAST e‐values, the descriptors based on the alignment of secondary structural elements (SSEA), and the descriptors based on the occurrence of PROSITE functional motifs. In a second phase, the three top‐performing descriptors were combined to obtain a final method with improved performance, which we named DescFold. Class membership was predicted by Support Vector Machine (SVM) learning. In comparison with the individual PSI‐BLAST‐based descriptor, the rate of remote homology identification increased from 33.7% to 46.3%. We found out that the composite set of descriptors was able to identify the true remote homolog for nearly every sixth sequence at the 95% confidence level, or some 10% more than a single PSI‐BLAST search. We have benchmarked the DescFold method against several other state‐of‐the‐art fold recognition algorithms for the 172 LiveBench‐8 targets, and we concluded that it was able to add value to the existing techniques by providing a confident hit for at least 10% of the sequences not identifiable by the previously known methods.
Specificity and reactive loop length requirements for crmA inhibition of serine proteases
Authors: Tesch Lisa D. , Raghavendra Manikanahally P. , Bedsted‐Faarvang Tina , Gettins Peter G.W. , Olson Steven T.
Published: January 2005

The viral serpin, crmA, is distinguished by its small size and ability to inhibit both serine and cysteine proteases utilizing a reactive loop shorter than most other serpins. Here, we characterize the mechanism of crmA inhibition of serine proteases and probe the reactive loop length requirements for inhibition with two crmA reactive loop variants. P1 Arg crmA inhibited the trypsin‐like proteases, thrombin, and factor Xa, with moderate efficiencies (∼102–104 M−1sec−1), near equimolar inhibition stoichiometries, and formation of SDS‐stable complexes which were resistant to dissociation (kdiss ∼10−7 sec−1), consistent with a serpin‐type inhibition mechanism. Trypsin was not inhibited, but efficiently cleaved the variant crmA as a substrate (kcat/KM of ∼106 M−1 sec−1). N‐terminal sequencing confirmed that the P1 Arg–P1′Cys bond was the site of cleavage. Altering the placement of the Arg in a double mutant P1 Gly‐P1′Arg crmA resulted in minimal ability to inhibit any of the trypsin family proteases. This variant was cleaved by the proteases ∼10‐fold less efficiently than P1 Arg crmA. Surprisingly, pancreatic elastase was rapidly inhibited by wild‐type and P1 Arg crmAs (105–106 M−1sec−1), although with elevated inhibition stoichiometries and higher rates of complex dissociation. N‐terminal sequencing showed that elastase attacked the P1′Cys–P2′Ala bond, indicating that crmA can inhibit proteases using a reactive loop length similar to that used by other serpins, but with variations in this inhibition arising from different effective P2 residues. These results indicate that crmA inhibits serine proteases by the established serpin conformational trapping mechanism, but is unusual in inhibiting through either of two adjacent reactive sites.
Tube construction in the watering pot shell Brechites vaginiferus (Bivalvia; Anomalodesmata; Clavagelloidea)
Authors: Harper Elizabeth M. , Morton Brian
Published: January 2005

The bizarre watering pot shells of the clavagellid bivalve Brechites comprise a calcareous tube encrusted frequently with sand grains and other debris, the anterior end of which terminates in a convex perforated plate (the ‘watering pot’). It has not proved easy to understand how such extreme morphologies are produced. Previously published models have proposed that the tube and ‘watering pot’ are formed separately, outside the periostracum, and fuse later. Here we present the results of a detailed study of the structure and repair of the tubes of Brechites vaginiferus which suggest that these models are not correct. Critical observations include the fact that the external surface of the tube and ‘watering pot’ are covered by a thin organic film, on to the inner surface of which the highly organized aragonite crystals are secreted. There is no evidence of a suture between the tube and the ‘watering pot’ or that the periostracum of the juvenile shell passes through the wall of the tube. Live individuals of B. vaginiferus are able to repair substantial holes in the tube or ‘watering pot’ by laying down a new organic film followed by subsequent calcareous layers. Brechites vaginiferus displays Type C mantle fusion, with the result that the whole animal is encased by a continuous ring of mantle and periostracum, thereby making it possible to secrete a continuous ‘ring’ of shell material. On the basis of these observations we suggest that watering pot shells are not extra‐periostracal but are the product of simple modification of ‘normal’ shell‐secreting mechanisms.
Role of Transthoracic Doppler Pulmonary Venous Flow Pattern in Large Atrial Septal Defects
Authors: Chockalingam Anand , Dass SriHari , Alagesan R. , Muthukumar D. , Rajasekar M.A. , Subramaniam T. , Jaganathan V. , Elangovan S.
Published: January 2005

Objective: Large uncomplicated atrial septal defect (ASD) alters the pulmonary venous flow (PVF) pattern. We aimed to study the role of transthoracic echocardiography (TTE) in estimating the PVF Doppler abnormalities in ASD. By repeating the study soon after ASD closure, we correlated the hemodynamics of atrial shunting with PVF patterns. Methods: This study was performed in a tertiary care referral teaching hospital in 2003. The TTE PVF patterns of 34 patients with ASD were studied. TTE study was reported by two blinded investigators independently. Surgical closure of ASD was done on eleven patients and the early postoperative PVF Doppler pattern was also studied with TTE. Results: PVF patterns were adequately recorded in 34 of 38 (90%) subjects with ASD with equal male: female ratio (n = 17 each). The mean age of the study group was 21.4 ± 8.7 years. ASD ranged from 10 to 38 mm in diameter with a mean of 18 ± 4.2 mm. Continuous antegrade wave (CAW, mean 68.45 ± 13.6 cm/s) replaced normally occurring S and D waves in all ASD patients. The atrial reversal wave was reduced or absent (mean 20.18 ± 3.28 cm/sec). After ASD closure, the CAW was replaced by the S (46.18 ± 7.5 cm/sec) and D waves (57.72 ± 9.7 cm/sec) with increase in atrial reversal wave to 27.81 ± 5.1 cm/sec. Conclusions: The S and D antegrade waves normally seen in PVF are replaced by a continuous antegrade wave in ASD. Atrial reversal wave is also reduced. PVF waveform becomes normal after ASD closure. TTE PVF Doppler pattern can help estimate ASD hemodynamics.
Subaortic Stenosis Produced by an Accessory Mitral Valve: The Role of Echocardiography
Authors: Popescu Bogdan A. , Ghiorghiu Ioana , Apetrei Eduard , Ginghina Carmen
Published: January 2005

Subaortic stenosis caused by an accessory mitral valve is an exceedingly rare finding. We report the case of an asymptomatic 14‐year‐old patient, in whom transthoracic echocardiography revealed an accessory mitral valve in the left ventricular outflow tract, producing mild subaortic stenosis. Except for an aneurysm of the interventricular septum, with no shunt, there were no other anomalies. Transesophageal echocardiography provided details about the morphology and location of the accessory valve. Being asymptomatic and having only a mild gradient, antibiotic prophylaxis for infective endocarditis and follow‐up were recommended. After 2 years the patient is asymptomatic, with a similar echocardiographic gradient.
Viable Myocardium: How Much Is Enough?
Authors: Salazar Holger P. , Talano James V.
Published: January 2005

Left ventricular systolic dysfunction is mainly a result of coronary artery disease (CAD). Decrease in myocardial contractility results as a response to a chronic hypoperfusion state that produces a change in cardiac myocyte metabolism, resulting in a perfusion‐contraction mismatch in which function is sacrificed for survival. If revascularization is performed in a timely fashion, metabolism can be restored leading to recovery of function. Through the use of noninvasive imaging modalities, assessing myocardial viability can be easily performed and will aid in selecting those patients who will benefit from revascularization. Viable myocardium can be identified by nuclear modalities that have a high sensitivity but a lower specificity, such as thallium‐201 single photon emission computed tomography and positron emission tomography (PET); or by the use of dobutamine stress echocardiogram (DSE), which has a decreased sensitivity but a better specificity. A modality that is increasingly being used with an overall good sensitivity and specificity is contrast‐enhanced magnetic resonance imaging. The purpose of this review is to explore the amount of myocardial viability that is relevant to pursue revascularization, since as myocardial function improves there is a decrease in morbidity and mortality from heart failure and arrhythmias.
Tissue inhibitor of metalloproteinse‐1 is a marker of diastolic dysfunction using tissue doppler in patients with type 2 diabetes and hypertension
Authors: Tayebjee M. H. , Lim H. S. , Nadar S. , MacFadyen R. J. , Lip G. Y. H.
Published: January 2005

Background  Tissue inhibitor of metalloproteinase‐1 (TIMP‐1) is associated with increased fibrosis of the extracellular matrix (ECM). Myocardial stiffness is a feature of diastolic dysfunction. We assessed circulating TIMP‐1 as a marker of diastolic dysfunction in patients with type 2 diabetes mellitus (DM) and hypertension, who were compared with healthy controls.

Methods  We recruited 54 patients (43 males; mean age 68 ± 5 years) with treated type 2 DM (i.e. controlled glycaemia, hypertension, hyperlipidaemia), 35 (30 males; 69 ± 8 years) treated nondiabetic hypertensives, and 31 healthy controls (18 males; 66 ± 5 years). Circulating TIMP‐1 was measured by ELISA. Using transthoracic echocardiography, the early (E) diastolic mitral inflow velocity was measured with pulse wave Doppler, and the early mitral annular velocity (e′), a recognized index of diastolic relaxation, was measured with tissue Doppler. The E/A ratio was also calculated and isovolumic relaxation time measured.

Results  Mean e′ levels differed significantly between controls, diabetics and hypertensives (P < 0·0001). Circulating TIMP‐1 was significantly different between patients and controls (P = 0·006), but there was no statistically significant difference between the DM and hypertension group. In both groups, only e′ was negatively correlated with TIMP‐1 levels, with a stronger correlation among the hypertensive patients (Spearman r = −0·544, P = 0·001) when compared with the diabetic group (r = −0·341, P = 0·011).

Conclusion  Diastolic relaxation is impaired in diabetes and hypertensive patients. The relationship between TIMP‐1 and e′ may reflect increased myocardial fibrosis and consequent diastolic dysfunction, which may be more prominent in hypertension.
Dietary intake of differently fed salmon; the influence on markers of human atherosclerosis
Authors: Seierstad S. L. , Seljeflot I. , Johansen O. , Hansen R. , Haugen M. , Rosenlund G. , Frøyland L. , Arnesen H.
Published: January 2005

Background  Cardioprotective effects of omega‐3 polyunsaturated fatty acids (n‐3 PUFAs) of marine origin are well recognized. Because of the shortness of marine resources vegetable oils are increasingly used in fish farming. The effects on human health of fish fed on vegetable oils are largely unknown.

Methods  In a double‐blinded intervention study, 60 patients with coronary heart disease (CHD) were randomly allocated to three groups consuming approximately 700 g per week for 6 weeks of differently fed Atlantic salmon: 100% fish oil (FO), 100% rapeseed oil (RO) or 50% of each (FO/RO), resulting in fillets with high, intermediate and low levels of marine n‐3 PUFAs. Patient analyses before and after the intervention period included serum fatty acid profile, serum lipoproteins, and markers of vascular inflammation.

Results  The serum fatty acid profiles of the patients after the intervention mirrored those of the corresponding salmon fillets and the respective salmon feeds. Significant differences between the groups were obtained, especially for the levels of total n‐3 PUFAs and the n‐3/n‐6 FA ratio, which were markedly increased in the FO group in contrast to the two other groups (P < 0·02 for all). Additionally, significant reductions of serum triglycerides and of vascular cell adhesion molecule‐1 and interleukin‐6 were obtained in patients receiving the FO diet when compared with the two other groups (P < 0·05 for all).

Conclusions  Tailor‐made Atlantic salmon fillets very high in n‐3 PUFAs of marine origin seem to impose favourable biochemical changes in patients with CHD when compared with ingestion of fillets with intermediate and low levels of marine n‐3 PUFAs, when replaced by rapeseed oil.
Four peptide hormones decrease the number of human breast adenocarcinoma cells
Authors: Vesely B. A. , Song S. , Sanchez‐Ramos J. , Fitz S. R. , Solivan S. M. , R. Gower W. , Vesely D. L.
Published: January 2005

Background  A family of six hormones, i.e. atrial natriuretic peptide, brain natriuretic peptide, C‐natriuretic peptide, long‐acting natriuretic peptide, vessel dilator, and kaliuretic peptide's main known biologic properties are sodium and water excreting and blood pressure lowering.

Methods and materials  These six hormones, each at their 1‐µm concentrations, were evaluated for their ability to decrease the number and/or proliferation of breast adenocarcinoma cells in culture for 24, 48, 72, and 96 h.

Results  Within 24 h, vessel dilator, long‐acting natriuretic peptide, kaliuretic peptide, atrial natriuretic peptide and 8‐bromo‐cyclic GMP, a cell‐permeable analogue of their intracellular mediator cyclic GMP (each at 1 µm), decreased the number of breast adenocarcinoma cells 60%, 31%, 27%, 40%, and 31%, respectively. There was no proliferation in the 3 days following this decrease in breast adenocarcinoma cell number. These same hormones decreased DNA synthesis 69% to 85% (P < 0·001). Brain natriuretic peptide and CNP did not decrease the number of breast adenocarcinoma cells or inhibit their DNA synthesis. Vessel dilator, long‐acting natriuretic peptide, kaliuretic peptide and 8‐bromo‐cyclic GMP (each at 1 µM) decreased the number of cells in the S phase of the cell cycle by 62%, 33%, 50%, and 39%, respectively (all P < 0·05). Natriuretic peptide receptors‐A and ‐C were present in the breast adenocarcinoma cells.

Conclusions  Four peptide hormones significantly decrease the number of human breast adenocarcinoma cells within 24 h and inhibit the proliferation of these cells for at least 96 h. Their mechanism of doing so involves inhibition of DNA synthesis and a decrease in cells in the S phase of the cell cycle mediated in part by cyclic GMP.
Effects of prolonged oral supplementation with l‐arginine on blood pressure and nitric oxide synthesis in preeclampsia
Authors: Rytlewski K. , Olszanecki R. , Korbut R. , Zdebski Z.
Published: January 2005

Background  Several lines of evidence point to the dysfunction of the endothelial l‐arginine–NO system in preeclampsia. We investigated the influence of dietary supplementation with l‐arginine on blood pressure and biochemical measures of NO production in women with preeclampsia in prospective, randomized, placebo‐controlled study.

Design  The 61 preeclamptic women on a standardized low nitrate diet received orally 3 g of l‐arginine (n = 30) or placebo (n = 31) daily for 3 weeks as a supplement to standard therapy. The differences between the two groups in systolic (SBP), diastolic (DBP) and mean arterial blood pressures (MAP) as well as in plasma levels of selected aminoacids, plasma concentrations of nitrates/nitrites (NOx) and in 24‐h urine NOx excretion were determined.

Results  After 3 weeks of treatment, values of SBP, DPB and MAP were significantly lower in the group taking l‐arginine as compared with the placebo group (SBP: 134·2 ± 2·9 vs. 143·1 ± 2·8; DBP: 81·6 ± 1·7 vs. 86·5 ± 0·9; MAP: 101·8 ± 1·5 vs. 108·0 ± 1·2 mmHg, P < 0·01). Importantly, treatment with exogenous l‐arginine significantly elevated 24‐h urinary excretion of NOx and mean plasma levels of l‐citrulline. Exogenous l‐arginine did not influence plasma concentrations of l‐arginine, l‐ornithine and methylated arginines (ADMA, SDMA, L‐NMMA).

Conclusions  We conclude that in women with preeclampsia, prolonged dietary supplementation with l‐arginine significantly decreased blood pressure through increased endothelial synthesis and/or bioavailability of NO. It is tempting to speculate that the supplementary treatment with l‐arginine may represent a new, safe and efficient strategy to improve the function of the endothelium in preeclampsia.
Atorvastatin reduces platelet‐oxidized‐LDL receptor expression in hypercholesterolaemic patients
Authors: Puccetti L. , Sawamura T. , Pasqui A. L. , Pastorelli M. , Auteri A. , Bruni F.
Published: January 2005

Background  Oxidized‐LDL (ox‐LDL) are proatherogenic and platelet‐activating molecules. Atorvastatin reduces platelet activity before cholesterol‐lowering action. CD36 and lectin‐like oxidized‐LDL receptor‐1 (LOX‐1) are specific ox‐LDL receptors expressed also in platelets. This study was planned to address whether the possible rapid effect of atorvastatin on platelets could be related to modulation of ox‐LDL receptors.

Materials and methods  Forty‐eight hypercholesterolaemic subjects requiring statin treatment (atorvastatin 20 mg day−1) after an ineffective diet regimen were evaluated for complete lipid‐profile (chromogenic); P‐selectin (P‐sel), CD36 and LOX‐1 expression (cytofluorimetric detection); circulating and platelet‐associated ox‐LDL (ox‐ and Pox‐LDL, ELISA); and intracellular citrullin recovery (iCit, HPLC) at baseline and 3, 6 and 9 days after inclusion in the study. Moreover, we studied 48 normal controls matched for sex and age.

Results  Platelet activity expressed by P‐sel (in resting and thrombin‐activated cells), CD36 and LOX‐1 were increased in hypercholesterolaemic subjects (all P < 0·01). Atorvastatin induced a reduction of CD36 at 6 days (P < 0·05); and P‐sel in resting (P < 0·001) and activated cells (P < 0·001) and LOX‐1 were reduced at 9 days (all P < 0·001) in association with decreased Pox‐LDL (P < 0·001) and increased iCit (P < 0·01). All data were obtained before a significant reduction of LDL and ox‐LDL was achieved (P = 0·109 and 0·113).

Discussion  Present data suggest that platelet deactivation by atorvastatin is related to CD36 and LOX‐1 expression reduction before significant LDL changes. Moreover, the modulation of LOX‐1 can be considered a self‐relevant antiatherothrombotic action of atoravastin owing to the important role of this receptor in the ox‐LDL‐mediated vascular damage.
Mechanism for Cavitation in the Mechanical Heart Valve With an Artificial Heart: Nuclei and Viscosity Dependence
Authors: Lee Hwansung , Taenaka Yoshiyuki , Kitamura Soichiro
Published: January 2005

Abstract: Until now, we have estimated cavitation for mechanical heart valves (MHV) mounted in an electrohydraulic total artificial heart (EHTAH) with tap water. However, tap water at room temperature is not a proper substitute for blood at 37°C. We therefore investigated fluid characterization in studies of MHV cavitation associated with the viscosity and nuclei content of a testing fluid. We used the Medtronic Hall valve mounted in the mitral position of the EHTAH. As testing fluids, tap water, distilled water, and glycerin solution were used. The valve‐closing velocity, pressure‐drop measurements, and a high‐speed video camera were employed to determine the cavitation intensity in MHV. Most of the cavitation bubbles were observed at the edge of the valve stop. Our analysis of the results indicates that squeeze flow is the major cause of cavitation in the Medtronic Hall valve. The cavitation intensity increased with increases in the fluid viscosity and the valve‐closing velocity. Even if cavitation intensity in glycerin solution was greater, the cavitation occurrence probability was less in glycerin solution than in tap water. Our results suggest that tap water contains particles that cause an increase in the cavitation occurrence probability. We conclude that cavitation intensity is greatly affected by the nuclei concentration in the fluid and the fluid viscosity.
Judicious Usage of Estrogen/Progesterone for Angiodysplasia
Authors: Takenaka Tsuneo , Kanno Yoshihiko , Suzuki Hiromichi
Published: January 2005

Abstract: We recently experienced a case of a female hemodialysis patient with multiple intestinal angiodysplasias. In 2001, she complained of melena, and angiographic embolization halted bleeding from ileum angiodysplasia. In 2002, she again complained of black stool. Abdominal angiography found jejunum angiodysplasia, and pharmacological therapy with estrogen/progesterone was required to stop the bleeding. Ethical demands to develop new hemodialyzers that do not release estrogen‐like substances are discussed.
“Blogs” and “Wikis” Are Valuable Software Tools for Communication Within Research Groups
Authors: Sauer Igor M. , Bialek Dominik , Efimova Ekaterina , Schwartlander Ruth , Pless Gesine , Neuhaus Peter
Published: January 2005

Abstract:  Appropriate software tools may improve communication and ease access to knowledge for research groups. A weblog is a website which contains periodic, chronologically ordered posts on a common webpage, whereas a wiki is hypertext‐based collaborative software that enables documents to be authored collectively using a web browser. Although not primarily intended for use as an intranet‐based collaborative knowledge warehouse, both blogs and wikis have the potential to offer all the features of complex and expensive IT solutions. These tools enable the team members to share knowledge simply and quickly—the collective knowledge base of  the group can be efficiently managed and navigated.
Methods of Failure and Reliability Assessment for Mechanical Heart Pumps
Authors: Patel Sonna M. , Allaire Paul E. , Wood Houston G. , Throckmorton Amy L. , Tribble Curt G. , Olsen Don B.
Published: January 2005

Abstract:  Artificial blood pumps are today's most promising bridge‐to‐recovery (BTR), bridge‐to‐transplant (BTT), and destination therapy solutions for patients suffering from intractable congestive heart failure (CHF). Due to an increased need for effective, reliable, and safe long‐term artificial blood pumps, each new design must undergo failure and reliability testing, an important step prior to approval from the United States Food and Drug Administration (FDA), for clinical testing and commercial use. The FDA has established no specific standards or protocols for these testing procedures and there are only limited recommendations provided by the scientific community when testing an overall blood pump system and individual system components. Product development of any medical device must follow a systematic and logical approach. As the most critical aspects of the design phase, failure and reliability assessments aid in the successful evaluation and preparation of medical devices prior to clinical application. The extent of testing, associated costs, and lengthy time durations to execute these experiments justify the need for an early evaluation of failure and reliability. During the design stages of blood pump development, a failure modes and effects analysis (FMEA) should be completed to provide a concise evaluation of the occurrence and frequency of failures and their effects on the overall support system. Following this analysis, testing of any pump typically involves four sequential processes: performance and reliability testing in simple hydraulic or mock circulatory loops, acute and chronic animal experiments, human error analysis, and ultimately, clinical testing. This article presents recommendations for failure and reliability testing based on the National Institutes of Health (NIH), Society for Thoracic Surgeons (STS) and American Society for Artificial Internal Organs (ASAIO), American National Standards Institute (ANSI), the Association for Advancement of Medical Instrumentation (AAMI), and the Bethesda Conference. It further discusses studies that evaluate the failure, reliability, and safety of artificial blood pumps including in vitro and in vivo testing. A descriptive summary of mechanical and human error studies and methods of artificial   blood   pumps   is detailed.