bluuebunny/crossref_metadata_2025 huggingface dataset:
Reciprocal tutoring using cognitive tools
Authors: Wong W.K. , Chan T.W. , Chou C.Y. , Heh J.S. , Tung S.H.
Published: December 2003

Abstract Reciprocal tutoring, where peers take turns to tutor each other, is an interesting style of social learning. In the Reciprocal Tutoring System (RTS), three computational cognitive tools were designed to facilitate reciprocal tutoring of Lisp programming on the network. The first is a Petal‐style of code–chunk interface, with which a tutee can enter Lisp code without making syntactic errors. The second tool is Diagnosis‐Hint Tree, with which a tutor can diagnose and comment on the errors in the tutee's program. The third one is a list of dialogue templates, with which the tutee and the tutor can communicate during the tutoring process. A three‐phase experiment was conducted, with each phase using different cognitive tools. In addition, with the help of the cognitive tools, RTS provides a virtual learning companion that can play tutor or tutee. Evaluation results reveal both the strengths and weaknesses of peer‐based learning and intelligent tutoring, with supports of different cognitive tools. Peer‐based learning supported by cognitive tools is a practical and attractive alternative to intelligent tutoring systems. Exactly which type of tutor is preferred depends on the tutee's cognitive, communication, and emotional needs in the tutorial context.
Action research in continuing professional distance education
Authors: Nunes M.B. , McPherson M.
Published: December 2003

Abstract In order to support the persistent evolution of Continuing Professional Distance Education (CPDE), an action research approach must be taken. For action research to be successful, explicit research models must be formulated and used. This paper presents such a model that conjugates pedagogical thinking, curriculum design and organisational context: the Educational Management Action Research (EMAR) model. However, the complexities and precise specifications required by Educational Systems Design (ESD) call for better support through development frameworks that incorporate educational and systems development philosophies. This paper presents and discusses an ESD framework that has been extensively used in the development of eLearning.
Integrating ICT into second language education in a vocational high school
Authors: Young S. S.C.
Published: December 2003

Abstract This study investigated the potential impacts of integrating the Internet into an English as a second language class in a vocational senior high school in Taiwan. Twenty‐nine students and a young male English teacher were involved. It was found that the students overall had a positive perception toward using Internet tools. This study indicated that the integration of information communication technology on the Internet with English facilitated the creation of a virtual environment that transformed learning from a traditional passive experience to one of discovery, exploration, and excitement in a less stressful setting. The study revealed that a computer‐mediated communication environment could lower students' psychological barriers to enable them to express their opinions freely and to communicate actively on the Internet and that it could also enhance their critical thinking, problem‐solving and communication skills through online activities or class homepage construction. An individual case study further revealed that a task‐oriented English tutoring strategy in association with email communication could motivate the student's writing competence but the student's language proficiency and grammatical accuracy did not improve. Finally, based on the findings, recommendations for future studies are made.
Developing a collaborative learning environment using a web‐based design
Authors: Neo M.
Published: December 2003

Abstract Today, technology is being used to support teachers in designing interesting and stimulating learning environments for students. In this paper, a web‐based design project is used to create a collaborative learning environment with the aim of inculcating collaborative skills into the learners and increasing their problem‐solving and critical thinking skills. The design project was created using multimedia tools such as Dreamweaver and Adobe‐Photoshop. Students worked in groups and were actively responsible for their own learning processes. Results showed that students engaged in collaborative learning enhanced their problem‐solving and critical thinking skills, learned to work in a team and became more autonomous learners.
Understanding and analysing activity and learning in virtual communities
Authors: Henri F. , Pudelko B.
Published: December 2003

Abstract  The purpose of this study is to provide a preliminary framework to observe, analyse and evaluate both activity and learning in virtual communities. So various types of virtual communities will be studied by examining their relationship to socialisation and learning. After a presentation of the main ideas of Wenger's social learning theory, the principal components of the social context of the emergence and evolution of virtual communities will be described. It will show how taking this context into account enables the definition of four principal types of virtual communities: community of interest, goal‐oriented community of interest, learners' community and community of practice and describe how the activity of these communities develops according to the goals they set for themselves and to the strategies they adopt to reach them. For each type of virtual community, an attempt will be made to determine the process of negotiation of meaning at the base of learning, and to describe the learning performed in terms of participation and reification processes.
Undergraduate students' gender differences in IT skills and attitudes
Authors: Lee A. C.K.
Published: December 2003

Abstract The worldwide concern about the gender gap in information technology and the lack of woman participation in computer science has been attributed to the different cultural influences to which boys and girls are subject. In The University of Hong Kong, girls achieved greater improvements in their computer skills than their male counterparts after completing one year of studies. Recognising their own progress has, in turn, boosted their confidence in using IT. The young women's estimates of their skill levels have doubled over the years from 1998 to 2000. Despite this recorded acceleration at the end of the academic years, girls were less confident of their abilities and possessed lower IT skill levels than boys before starting their university education, as found in surveys of freshmen's computer skills. This study compares the responses of student participants of the HKU/IBM Notebook Computer Programme, which started in 1998, in the self‐reported IT skills and attitudes of male and female students, in surveys conducted both at the beginning and again at the end of the freshman year. It also examines the achievement scores of the IT Proficiency Tests and the ‘Foundations to Information Technology’ courses administered for the student IT requirement for graduation.
Previews in hypertexts: effects on navigation and knowledge acquisition
Authors: Cress U. , Knabel O.B.
Published: December 2003

Abstract In hypertexts, previews can be used as local tools for navigation. They pop up when a link is activated and provide information about the linked page. In an experimental study with 50 participants the effect of previews on searching and knowledge acquisition was investigated. The participants had to explore a hypertext with the aim either to understand as much as they could or to search for information. Previews enhanced knowledge acquisition in both conditions and supported intentional and incidental learning. In the searching condition previews were used for link selection, even if they could not enhance the search results.
Characteristics of multimedia textbooks that affect post‐test scores
Authors: Mikk J. , Luik P.
Published: December 2003

Abstract The evaluation of computer software relies on the relationship between the characteristics of the software and the efficiency of its use. To find out which characteristics of the software can influence the level of acquired knowledge, an experiment was carried out with tenth grade students in Estonian schools. Fifty‐four students studied 35 units from different multimedia textbooks. Correlation coefficients between the post‐test score of the students and different characteristics of the textbooks were calculated. The correlation coefficients revealed five factor groups for the post‐test score: text, presentation of information on the computer screen, graphics, navigation, and students' self‐control.
Effects of vocabulary training by computer in kindergarten
Authors: Segers E. , Verhoeven L.
Published: December 2003

Abstract In the present study, intensive vocabulary training by computer was undertaken in a two‐year kindergarten programme in the Netherlands. In the intervention, 67 native and immigrant children in the first and second years of kindergarten played vocabulary games on the computer twice a week for a period of 15 minutes over 15 weeks. A control group of 97 kindergartners followed the regular curriculum. In a pre‐test‐training‐post‐test‐retention test design, positive effects of the computer training were found on a curriculum‐dependent vocabulary test. A trend was found towards positive effects of the computer training on a curriculum‐independent test for children in their second year of kindergarten. The results present an alternative and relatively teacher‐independent method to enlarge children's vocabularies.
Exact Skewness–Kurtosis Tests for Multivariate Normality and Goodness‐of‐Fit in Multivariate Regressions with Application to Asset Pricing Models*
Authors: Dufour Jean‐Marie , Khalaf Lynda , Beaulieu Marie‐Claude
Published: December 2003

We study the problem of testing the error distribution in a multivariate linear regression (MLR) model. The tests are functions of appropriately standardized multivariate least squares residuals whose distribution is invariant to the unknown cross‐equation error covariance matrix. Empirical multivariate skewness and kurtosis criteria are then compared with a simulation‐based estimate of their expected value under the hypothesized distribution. Special cases considered include testing multivariate normal and stable error distributions. In the Gaussian case, finite‐sample versions of the standard multivariate skewness and kurtosis tests are derived. To do this, we exploit simple, double and multi‐stage Monte Carlo test methods. For non‐Gaussian distribution families involving nuisance parameters, confidence sets are derived for the nuisance parameters and the error distribution. The tests are applied to an asset pricing model with observable risk‐free rates, using monthly returns on New York Stock Exchange (NYSE) portfolios over 5‐year subperiods from 1926 to 1995.
General‐to‐Specific Model Selection Procedures for Structural Vector Autoregressions*
Authors: Krolzig Hans‐Martin
Published: December 2003

Structural vector autoregressive (SVAR) models have emerged as a dominant research strategy in empirical macroeconomics, but suffer from the large number of parameters employed and the resulting estimation uncertainty associated with their impulse responses. In this paper, we propose general‐to‐specific (Gets) model selection procedures to overcome these limitations. It is shown that single‐equation procedures are generally efficient for the reduction of recursive SVAR models. The small‐sample properties of the proposed reduction procedure (as implemented usingPcGets) are evaluated in a realistic Monte Carlo experiment. The impulse responses generated by the selected SVAR are found to be more precise and accurate than those of the unrestricted VAR. The proposed reduction strategy is then applied to the US monetary system considered byChristiano, Eichenbaum and Evans (Review of Economics and Statistics, Vol. 78, pp. 16–34, 1996). The results are consistent with the Monte Carlo and question the validity of the impulse responses generated by the full system.
Specification Testing of Markov Switching Models*
Authors: Breunig Robert , Najarian Serinah , Pagan Adrian
Published: December 2003

This paper proposes a set of formal tests to address the goodness‐of‐fit of Markov switching models. These formal tests are constructed as tests of model consistency and of both parametric and non‐parametric encompassing. The formal tests are then combined with informal tests using simulation in combination with non‐parametric density and conditional mean estimation. The informal tests are shown to be useful in shedding light on the failure (or success) of the encompassing tests. Several examples are provided.
Time Series Concepts for Conditional Distributions*
Authors: Granger Clive W. J.
Published: December 2003

The paper asks the question – as time series analysis moves from consideration of conditional mean values and variances to unconditional distributions, do some of the familiar concepts devised for the first two moments continue to be helpful in the more general area? Most seem to generalize fairly easy, such as the concepts of breaks, seasonality, trends and regime switching. Forecasting is more difficult, as forecasts become distributions, as do forecast errors. Persistence can be defined and also common factors by using the idea of a copula. Aggregation is more difficult but causality and controllability can be defined. The study of the time series of quantiles becomes more relevant.
Genital Lesions in an Outbreak of Caprine Contagious Agalactia Caused by Mycoplasma agalactiae and Mycoplasma putrefaciens
Authors: Gil M. C. , Peña F. J. , Hermoso De Mendoza J. , Gomez L.
Published: December 2003

This paper reports on the genital lesions observed in adult male and female goats from a commercial flock in the Extremadura region of southwestern Spain, following an outbreak of contagious agalactia syndrome caused by Mycoplasma agalactiae and M. putrefaciens. Although both species were isolated from several organs, M. putrefaciens was the only agent isolated from the genital lesions reported here, characterized by desquamative salpingitis and cystic catarrhal metritis in females and by testicular degeneration in males. Mycoplasma putrefaciens was isolated from the testes of only one of the males examined.
Feature
Authors: Littlewood D. Timothy J. , Donovan Stephen K.
Published: December 2003

The fossil record contains many examples of the interactions that occurred between organisms. Thus, Cenozoic molluscs are commonly found encrusted by bryozoans, serpulid worms and balanid barnacles; ancient scleractinian corals and echinoderms may show unusual growth patterns as a response to organisms that have embedded themselves into the host's skeleton; fossil bones can preserve indications of biting, gnawing and trampling; and ancient leaves may retain traces of bite marks and leaf miners. Other evidence of interactions may be more cryptic or difficult to interpret, none more so than the evidence of ancient parasitism.
Establishment and characterization of two new cell lines derived from flounder, Paralichthys olivaceus (Temminck & Schlegel)
Authors: Kang M S , Oh M J , Kim Y J , Kawai K , Jung S J
Published: December 2003

Two new cell cultures from flounder, Paralichthys olivaceus (Temminck & Schlegel), flounder fin (FFN) cells from fin tissue and flounder spleen (FSP) cells from spleen tissue, were established and characterized. The cells multiplied well in Eagle's minimum essential medium, supplemented with 10% foetal bovine serum, and have been subcultured more than 100 times, becoming continuous cell lines. Modal diploid chromosome number of FFN and FSP cells was 64 and 62, respectively. Polymerase chain reaction products were obtained from FFN and FSP cells with primer sets of microsatellite markers of flounder. Optimal growth temperature was 20 °C and consisted of epithelioid cells. FFN and FSP cells showed cytopathic effects after inoculation of infectious pancreatic necrosis virus, marine birnavirus, chum salmon virus, infectious haematopoietic necrosis virus, spring viraemia of carp virus and hirame rhabdovirus. Thus these new cell lines may be useful for studying a wide range of fish viruses.
Tracing the route of Sphaerospora truttae from the entry locus to the target organ of the host, Salmo salar L., using an optimized and specific in situ hybridization technique
Authors: Holzer A S , Sommerville C , Wootten R
Published: December 2003

Sphaerospora truttae is an important pathogen of Atlantic salmon parr in Scottish aquaculture. To trace the early development of S. truttae and to overcome the common problem of detecting low numbers of cryptic, early myxosporean stages, a DNA‐based approach was applied in this study. Specific primers were designed for S. truttae from Atlantic salmon, based on 18S rDNA sequences, obtained from isolated myxosporean spores. These were 5′ biotin‐labelled and used in an optimized and rapid in situ hybridization (ISH) protocol, which provided a strong and specific signal of the parasite within host tissue sections and, at the same time, minimized structural damage to tissues due to processing. This methodology provided a reliable tool enabling the detection of S. truttae stages down to single cell level. Using ISH the epithelium of the gills was identified as the predominant entry locus of the parasite. By 3 days after infection S. truttae had penetrated the vascular epithelia and thereafter proliferated in the blood for at least 10 days before exiting the vascular system through capillary walls. From day 12 post‐infection onwards, the kidney, as well as the spleen and the liver, were invaded. Numbers of S. truttae invading the kidney (37.3%) differed little from numbers found in the spleen (35.3%) and the liver (27.4%). The latter organs represented a dead end in the development of S. truttae as all stages in these organs degenerated and sporogony was found to take place exclusively inside the renal tubules. Early sporogonic stages were found from day 25 post‐infection but mature spores only developed after at least 15 days of proliferation within the tubules.
Oral Vaccination against Rabies and the Behavioural Ecology of the Red Fox (Vulpes vulpes)
Authors: Vos A.
Published: December 2003

As a result of oral vaccination of foxes (Vulpes vulpes) against rabies, this virus disease has almost been completely eradicated from West‐ and Central Europe. In most countries, vaccine baits were distributed twice a year: during spring (March to May) and autumn (September to October). This strategy has shown to be able to control and eventually eradicate rabies. However, it remains to be clarified if this is the most cost‐effective strategy. Astonishingly, the behavioural ecology of the target species, the red fox, did receive only limited attention selecting the periods when baits should be distributed. Considering the behavioural ecology and rabies epidemiology of foxes, territory owners seem to play a key role in the spread and maintenance of rabies. Thus, oral vaccination campaigns should be targeted primarily at these animals. It is suggested that the optimal timing for bait distribution in Europe is late autumn (November) or early winter (December), depending on the prevailing climatic conditions. Additional campaigns, when financially feasible, can be implemented in order to maintain a high vaccination coverage during the remaining year. Furthermore, different baiting strategies can be selected in case of re‐infection or persistent residual foci.
Haematophagous Bats in Brazil, Their Role in Rabies Transmission, Impact on Public Health, Livestock Industry and Alternatives to an Indiscriminate Reduction of Bat Population
Authors: Mayen F.
Published: December 2003

Haematophagous bats exist only in Latin America, from México to the Northern provinces of Argentina. They are represented by three species, Desmodus rotundus, Diphylla ecaudata and Diaemus youngii. While two species feed only on blood of wild birds, one species, D. rotundus, causes losses feeding on livestock and could be a vector for rabies virus. The cases in which humans were bitten by the bat have increased in Brazil. Bats became a target of control activities by farming communities and local governments. Indiscriminate actions such as poisoning bats and destroying their roosts put the lives of other bat species, which are extremely important for the ecologic balance, at risk. The vaccination of exposed livestock against rabies, which would protect the endangered livestock, is not regularly carried out.

The importance and current status of D. rotundus in the transmission of rabies in Brazil, the Public Health aspects, the importance for the livestock industry are shown and the consequences of reducing bat population are discussed. Alternatives to an indiscriminate bat‐population reduction in the control of rabies are proposed.
Use of a Quantitative TaqMan‐PCR for the Fast Quantification of Mycobacteria in Broth Culture, Eukaryotic Cell Culture and Tissue
Authors: Lewin A. , Freytag B. , Meister B. , Sharbati‐Tehrani S. , Schäfer H. , Appel B.
Published: December 2003

The quantification of slow‐growing mycobacteria such as Mycobacterium tuberculosis or M. bovis from in vitro and in vivo samples is complicated by their long generation time, their ability to form aggregates, and their capacity to persist in a state of dormancy. We compared different methods for the establishment of growth curves for broth cultures of M. bovis bacille Calmette‐Guérin (BCG). A quantitative TaqMan‐PCR yielded results comparable with those obtained by protein quantification and measurement of the ATP content of the cultures. The quantitative TaqMan‐PCR furthermore turned out to be particularly suitable for the measurement of multiplication of BCG within eukaryotic cells. Furthermore, it is a fast method allowing an estimation of the mycobacterial load in tissue long before colony counts can be obtained.
Melatonin prevents disruption of hepatic reactive oxygen species metabolism in rats treated with carbon tetrachloride
Authors: Ohta Yoshiji , Kongo‐Nishimura Mutsumi , Matsura Tatsuya , Yamada Kazuo , Kitagawa Akira , Kishikawa Teruaki
Published: December 2003

Abstract: We reported that melatonin prevents the progression of carbon tetrachloride (CCl4)‐induced acute liver injury in rats possibly by attenuating enhanced lipid peroxidation and reduced glutathione depletion. Herein, we examined the effect of melatonin on the changes in hepatic reactive oxygen species (ROS) metabolism in rats with a single intraperitoneal injection of CCl4 (1.6 g/kg body weight); the intent was to clarify the therapeutic mechanism of the indoleamine on CCl4‐induced acute liver injury. Rats with and without CCl4 treatment received a single oral dose of melatonin (10, 50 or 100 mg/kg body weight) 6 hr after CCl4 treatment. Hepatic concentrations of ascorbic acid (ASC) and vitamin E (VE) and hepatic activities of superoxide dismutase (SOD), catalase (CAT), Se‐glutathione peroxidase (Se‐GSH‐Px), glutathione reductase (GSSG‐R), glucose‐6‐phosphate dehydrogenase (G‐6‐PDH), and xanthine oxidase (XO) were determined 6 and 24 hr after CCl4 treatment. The liver of CCl4‐treated rats showed reductions in ASC concentrations, and SOD activity and an increase in G‐6‐PDH activity at 6 hr after treatment and further decreases in ACS concentrations and SOD activity and also further increase in G‐6‐PDH activity in addition to decreases in CAT and GSSG‐R activities and increases in VE concentrations and XO activity at 24 hr after treatment. Melatonin attenuated the reductions in hepatic ASC concentrations and SOD, CAT and GSSG‐R activities and the increase in hepatic XO activity in a dose‐dependent manner without affecting either hepatic Se‐GSH‐Px activity or the increased hepatic VE concentration and G‐6‐PDH activity at 24 hr after CCl4 treatment. No dose of melatonin influenced hepatic ACS and VE concentrations and SOD, CAT, Se‐GSH‐Px, G‐6‐PDH, and XO activities in CCl4‐untreated rats. These results indicate that melatonin postadministered at pharmacological doses prevents the disruption of hepatic ROS metabolism associated with ASC, SOD, CAT, GSSG‐R, and XO, in addition to reduced glutathione, in CCl4‐treated rats.
Regulation of antioxidant enzymes: a significant role for melatonin
Authors: Rodriguez Carmen , Mayo Juan C. , Sainz Rosa M. , Antolín Isaac , Herrera Federico , Martín Vanesa , Reiter Russel J.
Published: December 2003

Abstract: Antioxidant enzymes form the first line of defense against free radicals in organisms. Their regulation depends mainly on the oxidant status of the cell, given that oxidants are their principal modulators. However, other factors have been reported to increase antioxidant enzyme activity and/or gene expression. During the last decade, the antioxidant melatonin has been shown to possess genomic actions, regulating the expression of several genes. Melatonin also influences both antioxidant enzyme activity and cellular mRNA levels for these enzymes. In the present report, we review the studies which document the influence of melatonin on the activity and expression of the antioxidative enzymes glutathione peroxidase, superoxide dismutases and catalase both under physiological and under conditions of elevated oxidative stress. We also analyze the possible mechanisms by which melatonin regulates these enzymes.
Melatonin protects against oxidative stress caused by 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine in the mouse nigrostriatum
Authors: Thomas Bobby , Mohanakumar Kochupurackal P.
Published: December 2003

Abstract: We tested the hypothesis that melatonin acts as a powerful hydroxyl radical (•OH) scavenger in vivo in the brain, and interferes with oxidative stress caused by the parkinsonian neurotoxin, 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP). We investigated the effect of melatonin on in vitro •OH production employing a Fenton‐like reaction in test tubes, and ex vivo •OH generation in isolated mitochondria induced by 1‐methyl‐4‐phenyl pyridinium (MPP+), as well as on in vivo •OH formation in the mouse striatum following systemic administration of MPTP. We also measured reduced glutathione (GSH) levels, and superoxide dismutase (SOD) activity in the nucleus caudatus putamen (NCP) and substantia nigra (SN), 7 days following MPTP and/or melatonin administration. Melatonin caused a significant and dose‐dependent inhibition of the production of •OH in the in vitro, ex vivo and in vivo experimental conditions. Melatonin caused no changes in monoamine oxidase‐B activity, in vitro in mitochondrial P2 fractions or in vivo following systemic administration. MPTP treatment in mice caused a significant depletion of GSH, and increased the specific activity of SOD both in SN and NCP on the seventh day. MPTP‐induced GSH depletion was dose‐dependently blocked in SN and NCP by melatonin. Higher doses of melatonin exhibited a synergistic effect on MPTP‐induced increase in the SOD activity in the SN. These results suggest that while GSH inhibition is a direct consequence of •OH generation following neurotoxin administration, the increase in SOD activity is a compensatory mechanism for removing superoxide radicals generated as the result of MPTP. Our results not only point to the potency of melatonin in blocking the primary insults caused by MPTP, but also provide evidence for triggering secondary neuroprotective mechanisms, suggesting its use as a therapeutic agent in neurodegenerative disorders, such as Parkinson's disease.
Melatonin suppresses cerebral edema caused by middle cerebral artery occlusion/reperfusion in rats assessed by magnetic resonance imaging
Authors: Torii Kunio , Uneyama Hisayuki , Nishino Hitoo , Kondoh Takashi
Published: December 2003

Abstract: Melatonin, a pineal secretory product synthesized from tryptophan, has been found to be effective against neurotoxicity. The present study was aimed at demonstrating the effectiveness of melatonin in vivo in reducing ischemia‐induced cerebral edema using magnetic resonance imaging (MRI). Rats were subjected to middle cerebral artery (MCA) occlusion/reperfusion surgery. Melatonin was administered twice (6.0 mg/kg, p.o.) just prior to 1 hr of MCA occlusion and 1 day after the surgery. T2‐weighted multislice spin‐echo images were acquired 1 day after the surgery. In the saline‐treated control rats, increases in T2‐weighted signals (water content) were clearly observed in the striatum and in the cerebral cortex. In the melatonin‐treated group, total volume of edema was reduced by 51.6% compared with control group (P < 0.01). The protective effect of melatonin against edema was more clearly observed in the cerebral cortex (reduced by 59.8%, P < 0.01) than in the striatum (reduced by 34.2%, P < 0.05). Edema volume in a coronal slice was the greatest at the level of the bregma. Suppression of cerebral edema by melatonin was more effective posterior than anterior to the bregma. Melatonin appeared to reduce the volume of the edematous sites rather than to shift the signal intensity distribution. The present MRI study clearly demonstrates the effectiveness of melatonin against cerebral edema formation in ischemic animals in vivo, especially in the cerebral cortex. Melatonin may be highly useful in preventing cortical dysfunctions such as motor, sensory, memory, and psychological impairments associated with ischemic stroke.
Synthesis of internal labeled standards of melatonin and its metabolite N1‐acetyl‐N2‐formyl‐5‐methoxykynuramine for their quantification using an on‐line liquid chromatography–electrospray tandem mass spectrometry system
Authors: Almeida Eduardo A. , Klitzke Clécio F. , Martinez Glaucia R. , Medeiros Marisa H. G. , Mascio Paolo Di
Published: December 2003

Abstract: Melatonin (N‐acetyl‐5‐methoxytryptamine) is implicated in physiologic changes related to light–dark cycles and has been recently found to display antioxidant properties. It is known that the reaction of melatonin with certain reactive oxygen and nitrogen species, such as hydrogen peroxide and singlet oxygen, produces N1‐acetyl‐N2‐formyl‐5‐methoxykynuramine (AFMK). We report herein on the development of a new liquid chromatography/tandem mass spectrometry (LC/ESI/MS‐MS) assay to quantitatively determine melatonin and AFMK. The stable isotopic internal standard of melatonin‐D3 was synthesized by the reaction of 5‐methoxytryptamine with deuterated acetyl chloride (CD3COCl). Labeled AFMK (AFMK‐D3) was obtained after photooxidation of melatonin‐D3. The predominant ion [M + H]+ in the full scan mass spectra of melatonin, melatonin‐D3, AFMK and AFMK‐D3 were located, respectively, at m/z = 233, 236, 265 and 268. The collision‐induced dissociation of the molecules revealed a predominant fragment at m/z = 174 for melatonin and melatonin‐D3 (loss of the N‐acetyl group), and at m/z = 178 for AFMK and AFMK‐D3 (loss of both the N‐acetyl and the N‐formyl groups). The m/z transitions from 233 to 174 (melatonin), from 236 to 174 (melatonin‐D3), from 265 to 178 (AFMK), and from 268 to 178 (AFMK‐D3) were therefore chosen for the multiple reaction monitoring detection experiments, ensuring a high specificity and an accurate quantification of melatonin and AFMK in human plasma.
Protective effect of melatonin on random pattern skin flap necrosis in pinealectomized rat
Authors: Gurlek Ali , Aydogan Hakan , Parlakpinar Hakan , Bay‐Karabulut Aysun , Celik Mehmet , Sezgin Nurzen , Acet Ahmet
Published: December 2003

Abstract: Random pattern skin flaps are still widely used in plastic surgery. However, necrosis in the distal portion resulting from ischemia is a serious problem, increasing the cost of treatment and hospitalization. Free oxygen radicals and increased neutrophil accumulation play an important role in tissue injury and may lead to partial or complete flap necrosis. To enhance skin flap viability, a variety of pharmacological agents have been intensively investigated. The aim of this study is to test the effects of melatonin, the chief secretory product of the pineal gland and a highly effective antioxidant, on random pattern skin flap survival in rats. Herein, to investigate the physiological and pharmacological role of melatonin on dorsal skin flap survival. Pharmacological (0.4, 4 and 40 mg/kg) levels of melatonin were given intraperitoneally (i.p.). For this, pinealectomized (Px) and sham operated (non‐Px) rats were used. The effects of melatonin on levels of malondialdehyde (MDA), nitric oxide (NO), glutathione (GSH) and the activities of glutathione peroxidase (GSH‐Px) and superoxide dismutase (SOD) were measured in the skin flap. The ratio of skin flap necrosis was compared among the experimental groups by using planimetry. MDA and NO levels were found to be higher in Px than non‐Px rats; while GSH levels and GSH‐Px, and SOD activities were reduced. Melatonin administration to Px rats reduced MDA and NO levels and increased GSH, GSH‐Px, SOD levels. Melatonin also reduced the ratio of flap necrosis determined by using planimetry and supported through the photography. In conclusion, these results show that both physiological and pharmacological concentrations of melatonin improve skin flap viability.
Involvement of phytochrome in regulation of transpiration: red-/far red-induced responses in the chlorophyll-deficient mutant of pea
Authors: Sokolskaya Svetlana V. , Sveshnikova Natalia V. , Kochetova Galina V. , Solovchenko Alexei E. , Gostimski Sergei A. , Bashtanova Ouliana B.
Published: December 2003

Transpiration rhythmicity and intensity were investigated in the chlorophyll-deficient mutant XL18 of Pisum sativum L. and in the phytochrome-deficient mutant aurea of Lycopersicon esculentum Mill. A custom-built psychrometer was used. In the XL18 mutant an acute transpiration response to monochromatic irradiation was observed such that red (R) light increased and far-red (FR) decreased transpiration rate, with equal rates of change. This result indicates that phytochrome is involved in regulation of transpiration. In wild type pea the chlorophyll-dependent component of transpiration was also shown to involve phytochrome. Monochromatic irradiation by red or far-red light induced an increase in transpiration with acceleration dependent on time of day. The response was irreversible by light of either wavelength. We conclude that both photoreceptors are involved in the acute response. Investigation of the daily course of transpiration revealed rhythmic changes in wild type pea and tomato under natural light conditions and in constant darkness. The rhythm was not apparent in the XL18 mutant in constant darkness, or in the aurea mutant under natural illumination. The latter results show that phytochrome, as a photoreceptor, is essential for maintaining the rhythm upon irradiation, while the photosynthetic component is crucial in darkness.
The relative limitation of photosynthesis by mesophyll conductance in co-occurring species in a temperate rainforest dominated by the conifer Dacrydium cupressinum
Authors: Lucia Evan H. De , Whitehead David , Clearwater Michael J.
Published: December 2003

The capacity to conduct CO2 from the intercellar spaces in leaves to the site of fixation (mesophyll conductance, gm) may pose a significant limitation to photosynthesis. Dacrydium cupressinum Sol. ex Lamb. (rimu), a native conifer of New Zealand, and other members of the Podocarpaceae evolved during the Jurassic when the partial pressure of CO2 exceeded 200 Pa. This species has low rates of photosynthesis and high levels of leaf nitrogen, which have led to the hypothesis that low gm restricts photosynthesis. Mesophyll conductance was estimated from gas-exchange and fluorescence measurements for this and other co-occurring tree species [Prumnopitys ferruginea D.�Don (miro), Weinmannia racemosa L.f. (kāmahi), Meterosideros umbellata Cav. (rata)]. Pinus radiata D. Don (radiata pine) and Phaseolus vulgaris L. (bean) were included to provide comparisons with a rapidly growing tree and herbaceous plant with relatively high photosynthetic rates. Mesophyll conductance was not statistically different among indigenous tree species but was lowest for D. cupressinum. This species also had the lowest ratio of mesophyll to stomatal conductance, gm / gst and was the only species where the decline in partial pressure of CO2 was greater from the intercellular air space to the site of fixation (16.3 Pa) than between the bulk air and the intercellular spaces (8.8 Pa), providing support for the hypotheses that low gm limits photosynthesis in this species. As a group, conifers had marginally lower gm and gm / gst ratio than angiosperms, but this difference was strongly influenced by the high values for Phaseolus vulgaris. That co-occurring members of the Podocarpaceae operated differently suggests that low gm may reflect a response to evolutionary pressures other than high atmospheric CO2 partial pressure.
Strategies of light energy utilisation, dissipation and attenuation in sixco-occurring alpine heath species in Tasmania
Authors: Williams Erica L. , Hovenden Mark J. , Close Dugald C.
Published: December 2003

Alpine environments are characterised by low temperatures and high light intensities. This combination leads to high light stress owing to the imbalance between light energy harvesting and its use in photochemistry. In extreme cases, high light stress can lead to the level of photo-oxidative damage exceeding the rate of repair to the photosynthetic apparatus. Plant species may vary in the mechanisms they use to prevent photodamage, but most comparisons are of geographically and ecologically distinct species. Differences in leaf colouration suggested that photoprotective strategies might differ among Tasmanian evergreen alpine shrub species. We compared chlorophyll fluorescence and leaf pigment composition in six co-occurring alpine shrub species on the summit of Mt Wellington, southern Tasmania, Australia, during spring and autumn. We found marked differences among species in light energy utilisation, attenuation and dissipation. Ozothamnus ledifolius maintained a large capacity for photosynthetic light utilisation and thus, had a low requirement for light dissipation. All five of the other species relied on xanthophyll-cycle-dependent thermal energy dissipation. In addition Epacris serpyllifolia, Richea sprengelioides and Leptospermum rupestre had foliar anthocyanins that would attenuate photosynthetically active light in the leaf. During spring, all species retained de-epoxidised xanthophylls through the night and the pre-dawn concentration of antheraxanthin and zeaxanthin was significantly correlated with reductions in pre-dawn Fv / Fm. We propose that these species use three photoprotective strategies to cope with the combination of high light and low temperature.
Succeeding with values
Authors: Crainer Stuart
Published: December 2003

Randall L Tobias is the former president, chairman and CEO of the pharmaceutical giant Eli Lilly. Under his leadership in the 1990s Eli Lilly experienced a dramatic turnaround and enjoyed one of the most successful periods in its history. Tobias' brand of highly ethical leadership won him plaudits during his career. He has now captured the lessons he learned in a book. Put the Moose On the Table, which argues that tough issues in business and in life need to be openly and honestly faced at all times. Interview by Stuart Crainer
Transnational corporations: international citizens or new sovereigns?
Authors: Rondinelli Dennis A
Published: December 2003

The expanding public roles of transnational corporations in private foreign aid, in self‐regulation and private certification of business practices, not to mention helping shape public policy, can be viewed as evidence of corporate citizenship and social responsibility or as a threat to democratic decision making and national sovereignty. Dennis A Rondinelli suggests that new systems of countervailing power may be needed to encourage further corporate citizenship while preventing potential abuses of political and economic power.
The seven myths of change management
Authors: Jarrett Michael
Published: December 2003

Michael Jarrett argues that while change may be constant the way we react to it should not be.
The radical fringe
Authors: Crainer Stuart
Published: December 2003

An interview with Gary Hamel
Competitive advantage the Toyota way
Authors: Fane Gary R , Vaghefi M. Reza , Van Deusen Cheryl , Woods Louis A
Published: December 2003

For a firm to experience long‐term sustained competitive advantage it must invest in human resources and deploy its scarce assets in the core areas that can most effectively provide the underpinning of a sustained competitive advantage. Gary R Fane, M Reza Vaghefi, Cheryl Van Deusen and Louis A Woods say that Japanese car maker Toyota is a supreme example of a company that has done just that.
Locality, Listedness, and Morphological Identity
Authors: Embick David
Published: December 2003

Abstract This paper investigates the syntax/morphology interface along four dimensions, in a study of English participial allomorphy. The results are developed in terms of the framework of Distributed Morphology. First, it is shown that considerations of syntactic locality play a direct role in morphological spell‐out. Second, the manner in which vocabulary insertion proceeds is argued to be divided into distinct cycles of insertion, with potentially different conditions on insertion applying in Root‐attached vs. non‐Root‐attached structural domains. Third, it is argued that the study of syncretisms must appeal to a notion that I call Substantive Identity in defining what it means for morphology to be ‘the same’ across the distinct cycles of insertion. Finally, it is shown that in addition to structural locality, string adjacency is also a factor in morphological realization.
The Left Elbow Constraint
Authors: Osborne Timothy
Published: December 2003

Abstract NPs in English and German adhere to a specific structural requirement: a pre‐modifier of a noun may not have a post‐modifier. A Dependency Grammar analysis of the phenomenon is provided. The analysis is summarized in terms of a structural constraint called the Left Elbow Constraint. This constraint states that a pre‐dependent of a noun may not have a post‐dependent. The prohibited structure forms a left elbow underneath the noun. The constraint is valid in a uniform manner for English and German, and it explains some curious word order differences in NPs across the two languages.
Revisiting English Secondary Predicates: can the Window be Opened Wider?
Authors: Pérez‐Guerra Javier
Published: December 2003

AbstractThe semantic, pragmatic and suprasegmental integration of the secondary predicate in the sentence as well as control issues have called into question the homogeneous analysis of secondary predicates, which has led to the recognition of two different configurations, namely, depictive and resultative constructions. Once each construction has been delimited on structural, semantic/pragmatic, morphosyntactic and intonational grounds, this paper deals with the widespread assumption that each type of secondary predicate must be assigned a distinct syntactic analysis, and tackles this task by suggesting syntactic solutions couched in a basic constituency framework. The final proposal allows not only the distinction between depictives/resultatives and other similar competing constructions but also its accommodation within the theory of transitivity from an English‐specific perspective.
Policing the Bargain: Coalition Government and Parliamentary Scrutiny
Authors: Martin Lanny W. , Vanberg Georg
Published: December 2003

Policymaking by coalition governments creates a classic principal‐agent problem. Coalitions are comprised of parties with divergent preferences who are forced to delegate important policymaking powers to individual cabinet ministers, thus raising the possibility that ministers will attempt to pursue policies favored by their own party at the expense of their coalition partners. What is going to keep ministers from attempting to move policy in directions they favor rather than sticking to the “coalition deal”? We argue that parties will make use of parliamentary scrutiny of “hostile” ministerial proposals to overcome the potential problems of delegation and enforce the coalition bargain. Statistical analysis of original data on government bills in Germany and the Netherlands supports this argument. Our findings suggest that parliaments play a central role in allowing multiparty governments to solve intracoalition conflicts.
Civil Liberties vs. Security: Public Opinion in the Context of the Terrorist Attacks on America
Authors: Davis Darren W. , Silver Brian D.
Published: December 2003

In the tradition of research on political tolerance and democratic rights in context, this study uses a national survey of Americans conducted shortly after the September 11, 2001 attack on America to investigate people's willingness to trade off civil liberties for greater personal safety and security. We find that the greater people's sense of threat, the lower their support for civil liberties. This effect interacts, however, with trust in government. The lower people's trust in government, the less willing they are to trade off civil liberties for security, regardless of their level of threat. African Americans are much less willing to trade civil liberties for security than whites or Latinos, even with other factors taken into account. This may reflect their long‐standing commitment to the struggle for rights. Liberals are less willing to trade off civil liberties than moderates or conservatives, but liberals converge toward the position taken by conservatives when their sense of the threat of terrorism is high. While not a forecast of the future, the results indicate that Americans' commitment to democratic values is highly contingent on other concerns and that the context of a large‐scale threat to national or personal security can induce a substantial willingness to give up rights.
Moral Virtue and the Limits of the Political Community in Aristotle'sNicomachean Ethics
Authors: Collins Susan D.
Published: December 2003

The recovery of Aristotle's view of the political community as guardian of the common good and moral educator has fueled a continuing debate about civic education and virtue. In focusing on the relation of virtue to the common good and that of the individual, however, this debate has obscured Aristotle's insight into virtue's status as an independent end. I argue that by taking account of this dimension of virtue, Aristotle's discussion of the particular moral virtues in the Nicomachean Ethics clarifies the nature and limits of civic education and shows that the full question of the human good emerges only with an investigation of the political community's highest and noblest pedagogic aims.
Accepting Authoritative Decisions: Humans as Wary Cooperators
Authors: Hibbing John R. , Alford John R.
Published: December 2003

Why are people more willing to accept some governmental decisions than others? In this article, we present results from a series of original experiments showing that people's reactions to a given outcome are heavily influenced by the procedure employed to produce the outcome. We find that subjects react much less favorably when a decision maker intentionally keeps a large payoff, thereby leaving the subject with a small payoff, than when that same payoff results from a procedure based on chance or on desert. Moreover, subjects react less favorably to outcomes rendered by decision makers who want to be decision makers than they do to identical outcomes selected by reluctant decision makers. Our results are consistent with increasingly prominent theories of behavior emphasizing people's aversion to being played for a “sucker,” an attitude that makes perfect sense if people's main goal is not to acquire as many tangible goods as possible but to make sure they are a valued part of a viable group composed of cooperative individuals.