bluuebunny/crossref_metadata_2025_split huggingface dataset:
γ-Aminobutyric Acid Neurons Integrate and Rapidly Transmit Permissive and Inhibitory Metabolic Cues to Gonadotropin-Releasing Hormone Neurons
Authors: Sullivan Shannon D. , Moenter Suzanne M. 
Published: December 2003

Abstract
Negative energy balance inhibits fertility by decreasing GnRH release; however, the mechanisms are not well understood. GnRH neurons can be excited by activation of γ-aminobutyric acid (GABA)A receptors, and GABAergic neurons provide a major synaptic input. We hypothesized that permissive metabolic signals mediated by leptin and inhibitory signals conveyed by neuropeptide Y (NPY) and opiates rapidly alter GABAA receptor-mediated drive to GnRH neurons. In fed and fasted female mice, GABAergic postsynaptic currents (PSCs) were recorded from GnRH neurons before and after in vitro treatment with leptin, NPY, or met-enkephalin. Leptin increased PSC frequency in fed and fasted mice, indicating that it increased presynaptic activity. Leptin also increased PSC size. Inhibiting leptin receptor signaling pathways within GnRH neurons abolished the latter effect, indicating a direct action on these cells. In fed, but not fasted, mice, NPY and met-enkephalin decreased PSC frequency in an antagonist-reversible manner, but did not alter PSC size. NPY-1 receptor antagonists alone increased frequency in fed and fasted mice, as did opiate receptor blockade in fasted animals, suggesting that endogenous NPY and opiates modulate GABAergic drive to GnRH neurons. These data suggest that GABAergic afferents integrate metabolic signals for delivery to GnRH neurons. Decreased sensitivity to NPY and opiates in fasted mice indicate that these peptides send physiologically relevant signals regarding energy balance to GnRH neurons.
Sicherheit mobiler Roborter (Safety of mobile robots)
Authors: Adamy Jürgen , Bechtel Peter 
Published: December 2003

Abstract
In der mobilen Robotik sind in Zukunft viele Anwendungen wie z.B. Reinigungs- und Transportaufgaben denkbar, die verglichen mit Industrierobotern viel höhere Sicherheitsanforderungen stellen. Dies liegt an der größeren erforderlichen Autonomie dieser Systeme und dem direkten Kontakt mit Menschen. Es ist daher nötig, Konzepte zu entwickeln, um die sichere Funktion von mobilen Robotern zu gewährleisten, wenn diese einsetzbar sein sollen. Ziel dieser Arbeit ist es, für verschiedene Typen von mobilen Robotern die typischen Gefährdungen herauszuarbeiten, sowie grundlegende Sicherheitsstrukturen und Anforderungen für den Einsatz zu beschreiben.
Internet-basiertes Lernen (Internet-based Learning)
Authors: Schmid Christian 
Published: December 2003

Abstract
Dieser Übersichtsbeitrag befasst sich weitgehend mit den technischen Aspekten des Online-Lernens und der zugehörigen Lernplattformen im Internet, da sich für das Lehrgebiet der Automatisierungstechnik besondere Anforderungen ergeben. Ausgehend vom Lernen und Experimentieren werden Online-Lernplattformen analysiert und die Besonderheiten für dieses Fachgebiet herausgearbeitet. Da das Web nur Grundfunktionen für Lernplattformen zur Verfügung stellt, werden Entwicklungen für Erweiterungen anhand von mehreren Beispielen aufgezeigt. Den Fernlaboren und der Fernlabortechnik wird besondere Aufmerksamkeit geschenkt und zuletzt ein ausführlicher Blick in die Zukunft gewagt.
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

Abstract
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

AbstractMehrjährige 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

Abstract
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

Zusammenfassung
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

Zusammenfassung
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

Zusammenfassung
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

AbstractWe 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

AbstractPurposeAlthough 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 methodsFactors 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.ResultIn 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.ConclusionIncreasing 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

AbstractMedical 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

AbstractPathologic 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

AbstractWe 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

AbstractThis 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.
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

AbstractObjective: 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

AbstractHeart 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.
The microbiology of glue ear in Australian Aboriginal children
Authors: Stuart J , Butt H , Walker P 
Published: November 2003

Objective:  To study the bacterial cultures of middle ear aspirates from 27 Aboriginal children with otitis media with effusion.Methods:  Standard bacteriological techniques were used to analyse the middle‐ear aspirates collected during surgery to insert grommets in 27 Aboriginal children. Swabs of the tympanic membrane were taken for comparison.Results:  Forty‐five aspirates were collected from 59 myringotomies. Positive cultures were obtained from 19 of these (13 children) with potentially pathogenic organisms identified in 11 children including Staphylococcus, Pseudomonas, Haemophilus influenzae, Moraxella, Achromobacter, Enterobacter and Corynebacterium.Conclusion:  This is only the second study to look at the bacteria in middle ear effusions in Aboriginal children. Streptococcus pneumoniae was notable in its absence as was found in a previous study.