bluuebunny/crossref_metadata_2025 huggingface dataset:
Reale Systeme im "virtuellen Labor" (Real Systems in "Virtual Laboratory")
Authors: Hoyer Helmut , Gerke Michael , Röhrig Christof , Bischoff Andreas , Masar Ivan , Ivanov Ivan
Published: December 2003

Internet-Technologien und neue Medien verändern die Ausbildung und den Erwerb von Information auch im Hochschul-Bereich nachhaltig. Speziell im Bereich der Automatisierungs- und Regelungstechnik sind hochwertige Animationen und Simulationen im Netz verfügbar, die durch Interaktion das Verständnis von Sachverhalten erleichtern. Die praktische Umsetzung von Lerninhalten wird durch Teleoperation von realen Systemen in "virtuellen Laborexperimenten" über das Internet ermöglicht. Der Beitrag beschreibt einen Ansatz zur Teleoperation eines Brückenkranes und eines inversen Pendels und die dazu benötigte Infrastruktur und Systemarchitektur. Zudem wird hier ein Mehrbenutzer-Szenario vorgestellt, welches die zeitgleiche Kollaboration mehrerer Praktikumsteilnehmer erlaubt.
Fernsteuerbare Versuchsanlagen als Bestandteile der Lehre im Internet am IPP der TUC (Experimental Plants Controlled over the Internet as Part of an E-learning Concept at the IPP of TUC)
Authors: Elzer Peter F. , Nikolic Vesna
Published: December 2003

Mehrjährige Erfahrungen mit Internet-gestützter Lehre am IPP der TUC (Institut für Prozess- und Produktionsleittechnik der TU Clausthal) haben gezeigt, dass die dabei verwendeten Lernmittel exploratives Lernen unterstützen und nach den in der Automatisierungstechnik erarbeiteten Prinzipien für Mensch-Maschine-Schnittstellen gestaltet sein müssen. Im Rahmen eines so gestalteten Lehr- und Lernsystems am IPP wurde 2002 ein über Internet fernsteuerbarer Praktikumsversuch in Betrieb genommen. Erfahrungen damit und weitere Ausbaupläne werden in diesem Artikel dargestellt.
Einsatz der Max-Plus/Min-Plus Algebra zur automatisierten Sicherheitsanalyse (The Application of Max-Plus/Min-Plus Algebra for an Automated Safety Analysis)
Authors: Längst Wolfgang , Lapp Andreas , Stübbe Kathrin , Schirmer Jürgen , Kraft Dieter
Published: December 2003

In dem vorliegenden Artikel wird ein Verfahren zur binären Beschreibung von verteilten ereignisdiskreten Systemen vorgestellt. Dieses wird als Grundlage für eine Sicherheitsanalyse in einer frühen Phase der Systementwicklung und zur automatisierten Ermittlung von Fehlerabhängigkeiten eingesetzt. Hierzu wird eine Systemgleichung verwendet, die ähnlich zu der Zustandsraumdarstellung der konventionellen Systemtheorie ist. Dabei erfolgt die Auswertung der Systemgleichung durch Anwendung der Max-Plus/Min-Plus Algebra. Die Vorgehensweise wird anhand des Beispiels eines vereinfachten Bremssystems erläutert.
Eine Methode zur vergleichenden Analyse der Gebrauchstauglichkeit von Business-to-Customer-Lösungen am Beispiel von Internet-Brokerage-Anwendungen (Comparative Usability Analysis of Business-to-Customer-Solutions: An Internet-Brokerage-Example)
Authors: Gierlinger Wolfgang , Stary Christian
Published: December 2003

Dieses Papier stellt eine integrative Methode zur Untersuchung der Gebrauchstauglichkeit aus funktionaler und Benutzbarkeit-Sicht von business-to-customer-Lösungen vor. Sie erlaubt Unternehmen, neben Domänenwissen Kriterien der Benutzbarkeit in eine vergleichende Analyse einzubringen. Somit wird eine umfassende Standortbestim-mung bezüglich unternehmensspezifischer Lösungen im Bereich business-to-costumer ermöglicht. Die Methode integriert heuristische Evaluierung und Scenario-Based-Testing und konn-te erfolgreich in einer internationalen Vergleichsstudie von Internet-Brokerage-Anwendungen eingesetzt werden.
OptoRAP – eine rekonfigurierbare optoelektronische Parallelprozessor-Architektur für die Bildvorverarbeitung (OptoRAP – a Reconfigurable Optoelectronic Parallel Processor Architecture for Image Pre-Processing)
Authors: Fey Dietmar , Loos Andreas
Published: December 2003

Intelligente Sensorchips sind dadurch gekennzeichnet, dass die Sensormatrix zusammen mit einem Signalprozessorkern auf einem Chip integriert wird. Solche Detektormatrix-Signalprozessor-Architekturen führen jedoch eine "unnatürliche" Parallel-Seriell-Wandlung durch, da ein paralleles Bild nach der Aufnahme seriell zu einem weitgehend seriell arbeitenden Signalprozessor zur Bildverarbeitung übertragen wird. Stattdessen wird in der hier vorgestellten Chip-Architektur das Bild sowohl parallel aufgenommen als auch parallel weiterverarbeitet, was zu einer wesentlichen Steigerung beim Durchsatz führt. Erreicht wird dies durch eine optoelektronische Feldrechner-Architektur, in der jedes Sensorelement mit einem lokalen Prozessorelement verbunden ist. Um die Größe eines einzelnen Prozessorelementes klein zu halten — was gleichbedeutend mit einer hohen Pixel-Auflösung ist — und dennoch eine Vielzahl von Operationen ausführen zu können, werden rekonfigurierbare Prozessorelemente angestrebt.
Gironimo – Transformationsoptimierte virtuelle Maschine (Gironimo – Translation Optimized Virtual Machine)
Authors: Menge Matthias , Schoppa Irenäus
Published: December 2003

Dieser Beitrag beschreibt die virtuelle Maschine Gironimo, die in ihrem Programmiermodell dem der weit verbreiteten Pentium-Prozessoren von Intel entspricht. Die Architektur der realen Prozessorfamilie wurde jedoch nicht einfach in Gironimo übernommen, sondern modifiziert, um so eine effektive Emulation durch andere verbreitete reale Prozessoren zu ermöglichen. Neben dem Pentium wurden der PowerPC, der UltraSPARC IIi, der ARM u.a. berücksichtigt.
Differential Ca2+responses induced by thrombin and thrombin‐receptor agonist peptides in HSY‐EA1 cells
Authors: Tanimura Akihiko , Shitara Akiko , Nezu Akihiro , Morita Takao , Tojyo Yosuke
Published: November 2003

We examined the mechanism by which protease‐activated receptor (PAR)‐1 is desensitized by comparing the effect of thrombin and the soluble agonist peptide SFLLRN on Ca2+responses in HSY‐EA1 cells. Thrombin‐induced increases in cytosolic Ca2+concentrations ([Ca2+]i) returned to basal levels within 60 s, but SFLLRN generated a sustained [Ca2+]ielevation. Interestingly, thrombin‐desensitized cells partially retained their ability to respond to SFLLRN. We desensitized PAR‐2 by pretreating cells with SLIGKV to confirm that this response was not due to PAR‐2, which can recognize SFLLRN. The highly specific PAR‐1 agonist peptide TFLLR also increased [Ca2+]iin PAR‐2‐desensitized cells pretreated with thrombin. These observations indicate that thrombin disarms PAR‐1 from further proteolytic activation, but leaves the receptor responsive for non‐tethered ligands.
Antidepressant prescribing and suicide rate in Northern Ireland
Authors: Kelly Christopher B , Ansari Tanzeel , Rafferty Thérèse , Stevenson Mike
Published: November 2003

Purpose

Although antidepressants are the most commonly used treatment for depressive illness, there is uncertainty if their use is associated with a reduction in suicide rate. Antidepressant prescribing in Northern Ireland has increased over fivefold in the decade 1989–1999. The authors sought to explore whether this increase was associated with a reduction in suicide rate taking into account social and political factors thought also to have an influence on suicide.

Materials and methods

Factors that have been suggested to influence suicide were entered into a linear regression with frequency of suicide and undetermined deaths (referred to as suicide rate) as the dependent variable. The above factors were antidepressant prescribing, unemployment rate, household alcohol expenditure and persons charged with terrorist offences. The rise in younger suicides, in recent decades, suggests this analysis should be carried out separately for younger (less than 30 years) and older (30 years and above) suicides separately. The predictors in the two models are based on aggregate data for the total group.

Result

In the younger group there was no association between antidepressant prescribing and suicide. For the older group increased antidepressant prescribing was associated with a reduction in suicide rate over the 10 years of the study.

Conclusion

Increasing antidepressant prescribing appears to be an effective strategy for reducing suicide. This has been demonstrated in older individuals.
Attitudes towards suicide and suicidal patients among medical students
Authors: Wallin U , Runeson B
Published: November 2003

Medical students’ attitudes towards suicide and suicidal patients were studied. The aim was also to determine whether attitudes differ between students in the beginning and end of studies. A questionnaire including own attitudes on death and suicide and psychosocial circumstances was filled in by 63% of first and final year students (306 of 485). The calculation included a factor analysis on items describing the attitudes to suicidal patients. Attitudes towards patients became influenced by the knowledge of mental disorders and by biological aspects of behaviour during the education. Final year students more often consider suicide to be an expression of psychiatric disease and thought that people trying to commit suicide were not responsible for their own actions. Thirty-four percent and 44% (ns) in the first and last years, respectively, reported suicidal ideas some time in their lives. Students with such a history of suicide thoughts were less optimistic about the possibility to help. Ongoing depressive/anxious symptoms were prevalent in 36/305 (12%) of students, but did not seem to affect their attitudes to patients. Female students had sought psychological/psychiatric help more often than males (26% and 10%,P< 0.01).
Failure of trabecular bone with simulated lytic defects can be predicted non‐invasively by structural analysis
Authors: Hong James , Cabe Greg D. , Tedrow John R. , Hipp John A. , Snyder Brian D.
Published: November 2003

Pathologic fracture is a significant risk for patients afflicted with metastatic or benign skeletal tumors. The quandary for physicians who treat these patients is that after making the diagnosis they must try to predict the load bearing capacity of the involved bone and the fracture risk from images seen in radiological examinations. Since bone fails at a relatively constant strain independent of density we demonstrate that using a mechanics of materials approach that the cross‐sectional structural properties of the bone most affected by the lytic defect governs the load bearing capacity of the entire bone.

Homogeneous cylindrical cores of trabecular bone were harvested from the vertebral bodies of whale spines, and prepared with circular or slotted through‐hole defects of varying sizes to simulate lytic skeletal tumors. Each specimen was imaged using quantitative computed tomography (CT), dual energy X‐ray absorptiometry (DXA), and magnetic resonance imaging (MRI) to obtain data for calculating cross‐sectional structural properties: axial, flexural, and torsional rigidity. The specimens were then divided into groups uniformly distributed with respect to defect sizes and shapes, and subjected to uniaxial tension, four‐point bending or torsion until failure.

A strong positive relationship was found between measured tensile yield loads, bending, and torsional yield moments vs. axial, flexural and torsional structural rigidities respectively, calculated from QCT, DXA, and MRI data [QCT: tension r2 = 0.951, bending r2 = 0.909, torsion r2 = 0.914 (p < 0.001); DXA: tension r2 = 0.926, bending r2 = 0.841, torsion r2 = 0.916 (p < 0.001), MRI: tension r2 = 0.916; bending r2 = 0.856, torsion r2 = 0.852 (p < 0.001)].

For cylindrical cores of trabecular bone with simulated lytic defects, the load bearing capacity of the entire core was directly proportional to the axial, bending, or torsional rigidity at the weakest cross‐section through the core containing the defect. Therefore structural rigidity analysis of cross‐sectional geometric data measured non‐invasively by QCT, DXA, and MRI of bones containing lytic defects may be used to predict the load bearing capacity of the involved bone and the relative fracture risk in vivo. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
A novel system of four‐dimensional motion analysis after total hip arthroplasty
Authors: Hagio Keisuke , Sugano Nobuhiko , Nishii Takashi , Miki Hidenobu , Otake Yoshito , Hattori Asaki , Suzuki Naoki , Yonenobu Kazuo , Yoshikawa Hideki , Ochi Takahiro
Published: November 2003

We have developed a novel system of four‐dimensional motion analysis after total hip arthroplasty (THA) that can aid in preventing dislocation by assessing safe range of motion for patients in several daily activities.

This system uses skeletal structure data from CT and motion capture data from an infrared position sensor. A 3‐D model reconstructed from CT data is combined with the motion capture data. Using this system, we analyzed hip motion when getting up from and sitting down in a chair or picking up an object while sitting in a chair in 17 patients (26 hips) who underwent THA. To assess the accuracy of this system's measurements, open MRI was used to evaluate positions of skin markers against bones in five healthy volunteers in various postures.

No impingement between bones and/or implants was found in any subjects during any activities. However, mean angle at the point of maximum hip flexion was different for each patient. The open MRI results indicated that average error in hip angle of the present system was within 5° for each static posture.

The functional position of the pelvis during daily activities must be taken into account when assessing the real risk of dislocation. The present system enables dynamic analysis involving not only alignment of components and bones of each patient, but also individual differences in characteristics of daily motions. Further investigation using this system can help determine safe ranges of motion for preventing hip dislocation, improving the accuracy of individualized guidance for patients regarding postoperative activities. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Fractional cointegration and tests of present value models
Authors: Caporale Guglielmo Maria , Gil‐Alana Luis A.
Published: November 2003

This paper tests the validity of present value (PV) models of stock prices by employing a two‐step strategy for testing the null hypothesis of no cointegration against alternatives which are fractionally cointegrated. Monte Carlo simulations are conducted to evaluate the power and size properties of this test, which is shown to outperform existing ones, and to compute appropriate critical values for finite samples. It is found that stock prices and dividends are both I(1) nonstationary series, but they are fractionally cointegrated. This implies that, although there exists a long‐run relationship, which is consistent with PV models, the equilibrium errors exhibit slow mean reversion. As the error correction term possesses long memory, deviations from equilibrium are highly persistent.
Multiple functions of tail‐anchor domains of mitochondrial outer membrane proteins
Authors: Habib Shukry J , Vasiljev Andreja , Neupert Walter , Rapaport Doron
Published: November 2003

Tail‐anchored proteins form a distinct class of membrane proteins that have a single membrane anchor sequence at their C‐terminus, the tail‐anchor. Their N‐terminal portion is exposed to the cytosol. We have studied the roles of tail‐anchor domains of proteins residing in the mitochondrial outer membrane. Four distinct functions of the tail‐anchor domain were identified. First, the domain mediates the targeting to mitochondria in a process that probably requires a net positive charge at the C‐terminally flanking segment. Second, tail‐anchor domains facilitate the insertion into the mitochondrial outer membrane. Third, the tail‐anchor is responsible for the assembly of the respective protein into functional multi‐subunit complexes; and fourth, tail‐anchor domains can stabilize such complexes.
Thiamine‐regulated gene expression of Aspergillus oryzae thiA requires splicing of the intron containing a riboswitch‐like domain in the 5′‐UTR
Authors: Kubodera Takafumi , Watanabe Mutsumi , Yoshiuchi Kumi , Yamashita Nobuo , Nishimura Akira , Nakai Susumu , Gomi Katsuya , Hanamoto Hideo
Published: November 2003

Exogenous thiamine regulates Aspergillus oryzae thiA, which is involved in thiamine synthesis. One of the two introns in its 5′‐untranslated region (5′‐UTR) contains motifs (regions A and B) highly conserved among fungal thiamine biosynthesis genes. Deletion of either region relieved the repression by thiamine and thiamine inhibited intron splicing, suggesting that regions A and B are required for efficient splicing. Furthermore, transcript splicing was essential for thiA gene expression. These observations suggest a novel gene expression regulatory mechanism in filamentous fungi, in which exogenous thiamine controls intron splicing to regulate gene expression. Interestingly, regions A and B constitute a part of a thiamine pyrophosphate‐binding riboswitch‐like domain that has been quite recently found in the 5′‐UTR of thiA.
Strength and voluntary activation of the quadriceps femoris muscle at different severities of osteoarthritic knee joint damage
Authors: Pap Géza , Machner Andreas , Awiszus Friedemann
Published: November 2003

Objective: Improvements of quadriceps motor deficits represent a major therapeutical target in knee osteoarthritis (OA). In the present study, we investigated changes in quadriceps function at different stages of osteoarthritic cartilage damage.

Methods: Measurements of quadriceps voluntary activation (VA) and maximum voluntary contraction (MVC) were performed by a twitch interpolation technique and the total muscular capacity (TMC) was calculated as the ratio of MVC and VA. We assessed 68 patients (56.7 ± 9.5 years) with stage II and 154 patients (65.6 ± 6.0 years) with stage IV chondropathy. As controls, we used 85 age related healthy subjects (58.1 ± 8.7 years).

Results: While TMC was significantly lower in stage IV (90.6 ± 43.7 N m) than in stage II chondropathy (109.6 ± 51.0) there were no differences in the MVCs between both groups. Quadriceps VA was even higher in stage IV (77.2 ± 13.2%) than in stage II chondropathy (70.8 ± 16.0%). In the controls, MVC, VA and TMC were significantly higher than in both OA groups.

Conclusion: We assume that a decrease of TMC might occur within the course of OA and, in consequence, VA increases to maintain quadriceps MVC. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Myocardial beta‐1 adrenoceptor down‐regulation in aging and heart failure: implications for beta‐blocker use in older adults with heart failure
Authors: Ahmed Ali
Published: November 2003

Heart failure is associated with increased sympathetic nervous stimulation that results in down‐regulation of myocardial beta‐1 receptors. The failing heart might depend more on beta‐2 receptors for positive inotropic support than the normal heart. Suppression of both beta‐1 and beta‐2 adrenoceptors by a non‐selective beta‐blocker, such as carvedilol, is likely to eliminate the failing heart's much needed inotropic support, resulting in an exacerbation of symptoms. Use of a beta‐1 selective blocker, such as metoprolol, on the other hand, is likely to be well tolerated. Unlike carvedilol, the use of metoprolol is associated with up‐regulation of beta‐1 receptors. The clinical significance of the pharmacodynamic differences between these two beta‐blockers in terms of their short‐term hemodynamic and long‐term beneficial effects is not clearly understood. However, in clinical trials, both carvedilol and metoprolol improved left ventricular function, heart failure symptoms and survival. Both drugs are well tolerated as well. Aging itself is associated with elevated myocardial and serum norepinephrine levels, which is associated with down‐regulation of beta‐1 receptors. In this article, we reviewed the literature to examine the clinical implications of this dual (age‐ and heart failure‐related) sympathetic stimulation and beta‐1 receptor down‐regulation on selection of beta‐blockers in older adults with heart failure.
Distribution and cycling of total organic carbon across the Almeria‐Oran Front in the Mediterranean Sea: Implications for carbon cycling in the western basin
Authors: Sempéré Richard , Dafner Evgeny , Van Wambeke France , Lefèvre Dominique , Magen Cédric , Allègre Sophie , Bruyant Flavienne , Bianchi Micheline , Prieur Louis
Published: November 2003

The dynamics of the total organic carbon (TOC) pool were studied during winter 1997–1998 in the Almeria‐Oran jet‐front (AOF) system. This system includes the modified Atlantic Jet, which spreads into the Mediterranean Sea from the Gibraltar Strait, its associated gyre, and the front between the Mediterranean and Atlantic waters. We determined TOC concentrations, bacterial production (BP), and primary production (PP) during field work, and labile dissolved organic carbon (l‐DOC) and bacterial growth efficiency (BGE), which were calculated from biodegradation experiments. Our results showed that the geostrophic Atlantic Jet, which is the most dynamic area (horizontal speed of 80 cm s−1 in the upper 100 m flowing eastward), was characterized by low TOC stocks integrated in the first 100 m (6330–6990 mmol C m−2), a proportion of l‐DOC of 5 ± 0.5%, a BGE of 15 ± 2% and moderate residence times of excess‐TOC (42 ± 7 days). Higher TOC stocks were found in the surrounding areas, including the Mediterranean (7298–7400 mmol C m−2) and gyre waters (6718–8315 mmol C m−2) whereas l‐DOC averaged 6 ± 0.9% and 15 ± 2%, respectively. BGE averaged 7 ± 1% in Mediterranean waters and 21 ± 3% in the gyre giving rise to slightly different excess‐TOC residence times (28 ± 1 days in Mediterranean waters and 109 ± 30 days in the gyre). We estimated that the transport of TOC and excess‐TOC within the Atlantic Jet averaged 8.04 ± 0.32 × 104 and 1.68 ± 0.32 × 104 mol C s−1, respectively.
Extension and partitioning in an oblique subduction zone, New Zealand: Constraints from three‐dimensional numerical modeling
Authors: Upton Phædra , Koons Peter O. , Eberhart‐Phillips Donna
Published: November 2003

Contraction, strike slip, and extension displacements along the Hikurangi margin northeast of the North Island of New Zealand coincide with large lateral gradients in material properties. We use a finite‐difference code utilizing elastic and elastic‐plastic rheologies to build large‐scale, three‐dimensional numerical models which investigate the influence of material properties on velocity partitioning within oblique subduction zones. Rheological variation in the oblique models is constrained by seismic velocity and attenuation information available for the Hikurangi margin. We compare the effect of weakly versus strongly coupled subduction interfaces on the development of extension and the partitioning of velocity components for orthogonal and oblique convergence and include the effect of ponded sediments beneath the Raukumara Peninsula. Extension and velocity partitioning occur if the subduction interface is weak, but neither develops if the subduction interface is strong. The simple mechanical model incorporating rheological variation based on seismic observations produces kinematics that closely match those published from the Hikurangi margin. These include extension within the Taupo Volcanic Zone, uplift over ponded sediments, and dextral contraction to the south.
Unexplained enhancements of CH3Br in the Arctic and sub‐Arctic lower troposphere during TOPSE spring 2000
Authors: Wingenter Oliver W. , Sive Barkley C. , Blake Donald R. , Rowland F. Sherwood , Ridley Brian A.
Published: November 2003

Elevated concentrations of methyl bromide (CH3Br) were observed in the Arctic atmospheric boundary layer (BL) during periods of widespread BL ozone (O3) depletion episodes (ODEs: O3 mixing ratios < 20 × 10−9 or parts per billion by volume, ppbv) particularly during major ODEs (MODES: O3 < 4 ppbv). No other organic gases measured during TOPSE (Tropospheric Ozone Production about the Spring Equinox) exhibited anti‐correlations with O3 during these ODEs. Methyl bromide has both natural and anthropogenic sources and contributes ∼ half of the bromine (Br) to the stratosphere, where it can catalytically destroy O3. Several known CH3Br sources are evaluated, but the current knowledge cannot explain the observed enhancements. If the mechanism is direct gas‐phase photochemical production, a significant portion of the unknown CH3Br source may be found.
Asymmetry and non‐linearity in upper tropospheric humidity variability
Authors: Kennett E. J. , Toumi R.
Published: November 2003

Changes in upper tropospheric humidity (UTH) are important in understanding the climatic response to increased anthropogenic forcing. This paper explores the asymmetry and non‐linearity in the response of subtropical UTH to tropical intraseasonal forcing. During northern winter, subtropical UTH anomalies, varying on intraseasonal timescales, propagate eastwards from northern Africa to the central Pacific. There is a discontinuity in the propagation of moist anomalies over the Tibetan Plateau, whilst dry anomalies show reduced propagation in the lee. This is consistent with the expected evolution of cyclones and anticyclones incident on high topography. Correlations of five‐day mean UTH show no significant linear correlation between moist anomalies over Indonesia and subtropical anomalies to the north. This appears to be explained by the limitation of dry anomalies in the region of low ambient vorticity south of the East Asian Jet Stream.
Large scale ocean circulation from the GRACE GGM01 Geoid
Authors: Tapley B. D. , Chambers D. P. , Bettadpur S. , Ries J. C.
Published: November 2003

The GRACE Gravity Model 01 (GGM01), computed from 111 days of GRACE K‐band ranging (KBR) data, is differenced from a global mean sea surface (MSS) computed from a decade of satellite altimetry to determine a mean dynamic ocean topography (DOT). As a test of the GGM01 gravity model, large‐scale zonal and meridional surface geostrophic currents are computed from the topography and are compared with those derived from a mean hydrographic surface. Reduction in residual RMS between the two by 30–60% (and increased correlation) indicates that the GGM01 geoid represents a dramatic improvement over older geoid models, which were developed from multiple satellite tracking data, altimetry, and surface gravity measurements. For the first time, all major current systems are clearly observed in the DOT from space‐based measurements.
Periodic magnetospheric substorms: Multiple space‐based and ground‐based instrumental observations
Authors: Huang Chao‐Song , Foster J. C. , Reeves G. D. , Le G. , Frey H. U. , Pollock C. J. , Jahn J.‐M.
Published: November 2003

Quasi‐periodic, sawtooth‐like variations of energetic plasma particle fluxes are often measured at geosynchronous orbit during magnetic storms. The outstanding problems are whether the sawtooth flux variations represent particle injections from the tail to the inner magnetosphere, whether the sawtooth variations correspond to substorm onsets, and what mechanism is responsible for the generation of periodic particle injections (or periodic substorms). In this paper, we present the measurements of multiple space‐based and ground‐based instruments in the magnetosphere and ionosphere during two magnetic storms. The Geotail satellite was located in the near tail between XGSM = −20 and −30 RE and detected periodic southward turnings of the magnetospheric magnetic field. The southward turnings of Bz are interpreted as the signature of periodic near‐tail reconnection and plasmoid formations. Geosynchronous satellites measured periodic gradual dropouts and rapid increases of energetic charged fluxes and magnetic field dipolarization. The IMAGE satellite measured enhanced emissions of energetic neutral atoms in the ring current and auroral brightenings. The Canadian Auroral Network for the OPEN Program Unified Study's photometers measured intensifications and latitudinal motion of auroral emissions. The auroral electrojet index showed periodic increases. These magnetospheric and ionospheric phenomena have the same periodicity and indicate the occurrence of periodic substorms. There is an excellent correspondence among the substorm signatures from all the measurements. The results show that periodic magnetospheric substorms can indeed occur during continuous southward interplanetary magnetic field, and the mean period in these two cases is ∼2.7 hours. The sawtooth variations of energetic plasma fluxes at geosynchronous orbit represent true particle injections from the tail to the inner magnetosphere. The sawtooth injections are related to the near‐tail reconnection and correspond to the onsets of periodic substorms.
Systemic Failure on a Grand Scale: The 14 August 2003 North American Blackout
Authors: Kappenman John G.
Published: November 2003

Now that an international investigative team has reported its findings from the events preceding the 14 August 2003 blackout in North America, definitive answers about “why and how” the large system failed can be used to understand how the network's operations rapidly spiraled out of control that day. Space weather effects have been ruled out as a cause of this blackout, but the small, multipoint failures that triggered it could easily have been caused by space weather.
Modeling conservative tracer transport in fracture networks with a hybrid approach based on the Boltzmann transport equation
Authors: Benke Roland , Painter Scott
Published: November 2003

Fractures often represent the primary transport pathways within low‐permeability rock. Continuum models based on the advective‐dispersion equation have difficulty representing the complex transport phenomenology observed in field studies. Discrete fracture network models can represent a greater range of transport behavior at the price of being computationally intensive, which restricts their application to small rock volumes. The linear Boltzmann transport equation from the kinetic theory of gases includes additional dependencies on the particle speed and direction of travel and can thus represent a greater range of transport behavior compared with the advective‐dispersion equation. The capability of the Boltzmann equation for modeling more complex transport behaviors of conservative tracers was evaluated. Parameters appearing in the Boltzmann equation were calibrated using small‐scale discrete fracture networks. The calibrated Boltzmann model can simulate at spatial/temporal scales that would be prohibitively expensive with a discrete fracture network. This hybrid approach successfully reproduced the results of discrete fracture network simulations in two dimensions.
Expression and characterization of an anti‐(hepatitis B surface antigen) glycosylated mouse antibody in transgenic tobacco (Nicotiana tabacum) plants and its use in the immunopurification of its target antigen
Authors: Ramírez Nadia , Rodríguez Meilyn , Ayala Marta , Cremata José , Pérez Marlene , Martínez Anazuria , Linares Marbelis , Hevia Yasser , Páez Rolando , Valdés Rodolfo , Gavilondo Jorge V. , Selman‐Housein Guillermo
Published: November 2003

Transgenic plants expressing recombinant immunoglobulins have arisen as an alternative technology for the large‐scale production of antibodies useful in therapeutics and in industrial processes. In the present paper we report the expression in transgenic tobacco (Nicotiana tabacum) of an anti‐HBsAg [anti‐(hepatitis B virus surface antigen)] mouse IgG1 mAb (monoclonal antibody), currently used for the industrial purification of the recombinant vaccine antigen. Using the sweet potato sporamin signal peptide, a KDEL (Lys‐Asp‐Glu‐Leu) ER (endoplasmic reticulum) anchorage domain, and a heavy‐ and light‐chain gene tandem construction, we generated F1 plants in which the expression of the antibody accounted for 0.5% of the total soluble proteins. The ‘plantibody’ (functional IgG antibody produced in plants) was easily purified by Protein A–Sepharose chromatography with a yield of ≈35 μg/g of fresh leaf material, and its glycosylation indicated that, irrespective of the KDEL signal, the molecule is modified in both the ER and Golgi. Finally, a successful comparison of the plantibody with the ascites‐derived mAb in the immunoaffinity purification of the vaccine recombinant HBsAg was performed. Taken as a whole, our results show that the large‐scale production of this antibody of industrial relevance in transgenic tobacco is feasible.
DNA strand scission by Fe(III) 2‐methylaminopyridine complex and hydrogen peroxide
Authors: El‐Sayed Ibrahim H. , El‐Masry Samir A.
Published: November 2003

Oxidative DNA damage is involved in mutagenesis, carcinogenesis, aging, radiation effects and also in the action of several anticancer drugs. Accumulated evidence indicates that iron may play an important role in these processes. The conversion of the closed circular double‐stranded supercoiled plasmid pcDNA3 into the nicked circular and linear forms was used to investigate DNA nicking induced by the reactions of an iron complex of 2‐methylaminopyridine (L), which exhibited a pronounced superoxide dismutase‐mimetic activity and antitumour activity with H2O2. Hence the dose–response curve for the [FeL2Cl2]Cl·H2O‐mediated H2O2‐dependent DNA nicking was studied. For a fixed concentration of [FeL2Cl2]Cl·H2O (25 μM), the concentration of H2O2 producing a maximum extent of DNA nicking was 100 μM. The effects of these two constituents are synergistic. The biological antioxidants such as glycerol, sodium azide and superoxide dismutase significantly inhibited DNA breakage induced by [FeL2Cl2]Cl·H2O and hydrogen peroxide.
Shear‐induced release of disabled herpes simplex virus from baby‐hamster kidney cells
Authors: Lotfian Pantea , Levy M. Susana , Coffin Rob , Ward John , Shamlou Parviz Ayazi
Published: November 2003

A new process route is proposed to increase the production yield of disabled herpes simplex virus type 1 (HSV‐1 DIS). Infected baby‐hamster kidney (BHK) cells were subjected to a range of shear rates between 3.69×103 s−1 and 51.3×103 s−1 in the gap between a pair of co‐axial cylinders. Analysis of the supernatant fractions of sheared material established that optimal virus release was achieved by exposing the infected cells to a shear rate of 42.7×103 s−1 for a period of 1 min. Compared with the current laboratory process, the titre of HSV‐1 DIS was increased over 30‐fold, from about 1×106 to 30×106 pfu (plaque‐forming units)/ml. Evaluation of the supernatant fractions by flow cytometry, total protein assay, PAGE and dot‐blot assays showed no evidence of cell disruption, supporting the hypothesis that shear‐induced release of the cell‐membrane‐bound virus was achieved without compromising downstream purification. The proposed method is scaleable, and since no additional chemicals are required, it provides an attractive option for enhanced recovery of virus particles for therapeutic applications.
Ligand-induced recruitment of Na+/H+-exchanger regulatory factor to the PDGF (platelet-derived growth factor) receptor regulates actin cytoskeleton reorganization by PDGF
Authors: DEMOULIN Jean-Baptiste , SEO Jeong Kon , EKMAN Simon , GRAPENGIESSER Eva , HELLMAN Ulf , RÖNNSTRAND Lars , HELDIN Carl-Henrik
Published: November 2003

Proteins interacting with the human PDGF (platelet-derived growth factor) β-receptor were isolated using immobilized peptides derived from the receptor C-terminus as a bait. We identified two PDZ domain proteins, namely NHERF (Na+/H+ exchanger regulatory factor, also called EBP50) and NHERF2 (E3KARP, SIP-1, TKA-1), which have been shown previously to associate with the murine PDGF receptor [Maudsley, Zamah, Rahman, Blitzer, Luttrell, Lefkowitz and Hall (2000) Mol. Cell. Biol. 20, 8352–8363]. In porcine aortic endothelial cells and in fibroblasts, NHERF recruitment was induced by PDGF treatment, but the receptor kinase activity was not required for the formation of the complex, suggesting that NHERF was not recruited in a phosphotyrosine-dependent manner. Instead, the interaction was abolished by mutation of the consensus C-terminal PDZ-interacting domain of the receptor (Leu-1106 to Ala), or truncation of the last 75 amino acid residues of the receptor. Disruption of NHERF binding to the receptor enhanced actin filament reorganization, but did not affect PDGF-induced mitogenicity and chemotaxis. Although NHERF was initially characterized as a factor required for intracellular pH regulation by β2-adrenergic receptors, we observed that it was not involved in pH regulation by PDGF. Collectively, these results suggest that the ligand-induced association of NHERF PDZ domain with the PDGF receptor tyrosine kinase controls the extent of cytoskeleton reorganization in response to PDGF.
Functional specificity of two hormone response elements present on the human apoA-II promoter that bind retinoid X receptor α/thyroid receptor β heterodimers for retinoids and thyroids: synergistic interactions between thyroid receptor β and upstream stimulatory factor 2a
Authors: HATZIVASSILIOU Eudoxia , KOUKOS George , RIBEIRO Agnes , ZANNIS Vassilis , KARDASSIS Dimitris
Published: November 2003

DNA binding and mutagenesis in vitro established that the −67/−55 region of the apoA-II (apolipoprotein A-II) promoter contains a thyroid HRE (hormone response element), which strongly binds RXRα (retinoid X receptor α)/T3Rβ (thyroid receptor β) heterodimers and weakly T3Rβ homodimers, but does not bind other homo- or heterodimers of RXRα or orphan nuclear receptors. Transactivation was abolished by point mutations in the thyroid HRE. In co-transfection experiments of HEK-293 (human embryonic kidney 293) cells, the −911/+29 human apoA-II promoter was transactivated strongly by RXRα/T3Rβ heterodimers in the presence of RA (9-cis retinoic acid) or T3 (tri-iodothyronine). Homopolymeric promoters containing either three copies of the −73/−40 (element AIIAB) or four copies of the −738/−712 (element AIIJ) apoA-II promoter could be transactivated by RXRα/T3Rβ heterodimers in COS-7 cells only in the presence of T3 or RA respectively. RXRα/T3Rβ heterodimers and USF2a (upstream stimulatory factor 2a) synergistically transactivated the −911/+29 apoA-II promoter in the presence of T3. USF2a also enhanced the activity of a GAL4–T3Rβ fusion protein in the presence of T3 and suppressed the activity of a GAL4–RXRα fusion protein in the presence of RA. These findings suggest a functional specificity of the two HREs of the apoA-II promoter for retinoids and thyroids, which is modulated by synergistic or antagonistic interactions between RXRα/T3Rβ heterodimers and the ubiquitous transcription factor USF2a.
Identification of two functional nuclear localization signals in DNase γ and their roles in its apoptotic DNase activity
Authors: SHIOKAWA Daisuke , SHIKA Yukari , TANUMA Sei-ichi
Published: November 2003

Among DNase I family members, only DNase γ causes DNA fragmentation during apoptosis. However, the molecular basis for this functional feature of DNase γ is poorly understood. Here we describe the identification of functional NLSs (nuclear localization signals) in DNase γ and their roles in its apoptotic function. DNase γ contains two NLSs: a classical bipartite-type NLS (NLS1) located in the N-terminal half, and a short basic domain (NLS2) at the C-terminus. No potential NLSs are found in the primary structures of other DNase I family DNases. Inactivation of either NLS1 or NLS2 causes reduced DNA ladder-producing activity in DNase γ. Disruption of NLS2 suppresses ladder formation more effectively than disruption of NLS1. DNase γ doubly mutated in both NLSs is enzymically active, but no longer catalyses apoptotic DNA fragmentation. Although DNase I fails to produce ladder formation during apoptosis, DNase I fused to NLS2 of DNase γ through its C-terminus is able to catalyse DNA fragmentation in apoptotic cells. These results indicate that the presence of either NLS1 or NLS2 is necessary for the apoptotic function of DNase γ, and that the most important domain for this function is NLS2. These findings also explain the lack of apoptotic DNase activity in the other DNase I family DNases.
BMP-1-mediated proteolytic processing of alternatively spliced isoforms of collagen type XI
Authors: MEDECK Ryan J. , SOSA Sergio , MORRIS Nicholas , OXFORD Julia Thom
Published: November 2003

Collagen type XI is a minor constituent of heterotypic collagen fibrils of developing cartilage and plays a regulatory role in fibril diameter. Collagen type XI is a heterotrimer composed of the α1, α2 and α3 chains. The mRNA encoding exons 6a, 6b and 8 of the α1 chain are expressed alternatively to generate six possible isoforms. The 6b-containing isoform has the most restricted distribution of all isoforms. It is first localized in the developing long bone, where mineralized tissue initially forms, and is later restricted to regions of cartilage that will be subsequently converted into bone. Bone morphogenetic protein 1 (BMP-1) and related proteins cleave procollagens I–III, V and VII, yielding triple-helical molecules that associate into collagen fibrils. The present study demonstrates that the α1 chain of collagen type XI can serve as a substrate for BMP-1. In addition, the efficiency with which BMP-1 processes different isoforms of the α1 chain varies. The amino acid sequence adjacent to the processing site influences the rate and extent of processing, as do sequences further away. Smaller fragments identified from cartilage extracts indicated that processing by BMP-1, in combination with other processing enzymes, generates small fragments of p6b-containing isoforms.
Nuclear transit of human zipcode-binding protein IMP1
Authors: NIELSEN Jacob , ADOLPH Sidsel K. , RAJPERT-De MEYTS Ewa , LYKKE-ANDERSEN Jens , KOCH Grete , CHRISTIANSEN Jan , NIELSEN Finn C.
Published: November 2003

The human IMPs (insulin-like growth factor II mRNA-binding proteins) belong to a vertebrate zipcode-binding protein family consisting of two RNA recognition motifs and four K homology domains and have been implicated in cytoplasmic mRNA localization, turnover and translational control. In the present study, we show that IMP1 is capable of translocating into nuclei of NIH 3T3 fibroblasts and its immunoreactivity is present in the nuclei of human spermatogenic cells. IMP1 does not contain a simple import signal, but nuclear entry was facilitated by disruption of RNA binding and cytoplasmic granule formation. IMP1 contains two NESs (nuclear export signals) within the RNA-binding K homology domains 2 and 4. The former is a leucine-rich leptomycin B-sensitive NES, whereas the latter is a leptomycin B-insensitive NES. Taken together, these results indicate that IMP1 may attach to its target mRNAs in the nucleus and thereby define the cytoplasmic fate of the transcripts.
Cutaneous vascular reactivity is reduced in aging and in heart failure: association with inflammation
Authors: ANDERSSON S. E. , EDVINSSON M.-L. , EDVINSSON L.
Published: November 2003

In the present study, we have investigated whether changes in vascular reactivity in congestive heart failure (CHF) patients can be detected in the cutaneous microvessels and whether these changes are due to endothelial dysfunction, are affected by increasing age and related to an ongoing inflammation. The responses to local warming and iontophoretically administered endothelium-dependent and -independent vasodilators were investigated in healthy young adults, healthy elderly adults and elderly adults with CHF. The results were correlated with plasma concentrations of vascular risk factors and markers for endothelial dysfunction and inflammation. The vasorelaxant responses were reduced in the elderly groups and were attenuated further in the CHF group. This group also had increases in levels of several markers associated with inflammation, higher blood glucose and homocysteine levels, a lower low-density lipoprotein–cholesterol and a rise in the concentration of von Willebrand factor, indicating a prothrombotic endothelial function. The severity of the heart failure, measured as the plasma level of brain natriuretic peptide, correlated with the intensity of inflammation and to the changes in vascular risk factors and endothelial function. It is concluded that the reactivity of the cutaneous microvessels is reduced with age, and the presence of CHF causes a further impairment. There is endothelial dysfunction in CHF, but it is uncertain to what extent this contributes to the reduced vasodilatory capacity. The inflammatory response appears central for many of the manifestations of the CHF syndrome.
Myogenic, mechanical and structural characteristics of resistance arterioles from healthy and ischaemic subjects
Authors: COATS P.
Published: November 2003

In critical limb ischaemia (CLI), the ability to regulate regional blood flow in the diseased portion of the leg would appear to be severely compromised. Considering this, pressure-dependent myogenic and mechanical properties of resistance arterioles isolated from control subjects and from patients with CLI were studied. Using confocal microscopy and pressure myography, subcutaneous resistance arteriole structure and function were compared between subcutaneous arterioles isolated from healthy volunteers [control subcutaneous (CS)] and non-diseased proximal subcutaneous (PS; internal control) and distal subcutaneous (DS) arterioles from the diseased ischaemic part of the limb from patients with CLI. Significant wall atrophy was observed in DS arterioles compared with PS and CS arterioles. Passive pressure-dependent mechanical properties were significantly altered in the diseased arterioles compared with PS and CS arterioles. Active pressure-dependent myogenic tone was completely absent in DS arterioles. The atrophic structural remodelling in DS arterioles were correlated with the changes in vascular mechanics, but not with the ability of these arterioles to contract in response to chemical stimuli. However, active pressure-dependent myogenic tone was absent in the DS arterioles. The combination of altered pressure-dependent passive mechanical and active myogenic tone goes some way in explaining CLI sequelae and poor outcome following surgical revascularization experienced by these patients.
The A‐mode sutural ontogeny in prolecanitid ammonoids
Authors: Korn Dieter , Ebbighausen Volker , Bockwinkel Jürgen , Klug Christian
Published: November 2003

The generally accepted theory of a U‐mode sutural ontogeny of prolecanitid ammonoids and their descendants is refuted. The basic suture formula of the order Prolecanitida is E A L U I (not E L U2 U1 I), resembling that of derived members of the suborder Tornoceratina (their phylogenetic ancestors), and of the suborder Goniatitina. During phylogeny of the prolecanitids, secondary umbilical lobes are introduced and lead to multilobate forms. In early ceratites, the original L lobe disappeared, and an increase in sutural elements took place by the introduction of supplementary U lobes. Consequently, sutural nomenclature of Permian ceratites and Mesozoic ammonoids has to be modified.
A crown‐group galliform bird from the Middle Eocene Bridger Formation of Wyoming
Authors: Gulas‐Wroblewski Bonnie E. , Wroblewski Anton F.‐J.
Published: November 2003

Despite an extensive described fossil record of Galliformes (Aves: ‘landfowl’), very few specimens have been considered within a phylogenetic context. Here we present a cladistic analysis and description of a new, well‐preserved and well‐dated fossil specimen from the Middle Eocene Bridger Formation of Wyoming (c. 50 Ma). Amitabha urbsinterdictensis gen. et. sp. nov. is assigned to Galliformes on the basis of the presence of derived characters including double, and open, incisurae laterales on the sternum and an incisura capitis of the proximal humerus that is enclosed from the crus dorsale fossa by a distinct ridge. Amitabha is considered to be a member of the large and diverse ‘phasianoid’ clade of Galliformes (including, for example, the pheasants, peafowl and turkeys) owing to a lack of extensive pneumaticity in the sternal plate. The age of this avian taxon and degree of preservation allow for a discussion of the use of fossil birds for the calibration of ‘molecular clock’ hypotheses and dating divergences within Neornithes in general, and Galliformes in particular.