bluuebunny/crossref_metadata_2025 huggingface dataset:
Developmental growth in students' concept of energy: Analysis of selected items from the TIMSS database
Authors: Liu Xiufeng , McKeough Anne
Published: March 2005

The aim of this study was to develop a model of students' energy concept development. Applying Case's (1985, 1992) structural theory of cognitive development, we hypothesized that students' concept of energy undergoes a series of transitions, corresponding to systematic increases in working memory capacity. The US national sample from the Third International Mathematics and Science Study (TIMSS) database was used to test our hypothesis. Items relevant to the energy concept in the TIMSS test booklets for three populations were identified. Item difficulty from Rasch modeling was used to test the hypothesized developmental sequence, and percentage of students' correct responses was used to test the correspondence between students' age/grade level and level of the energy concepts. The analysis supported our hypothesized sequence of energy concept development and suggested mixed effects of maturation and schooling on energy concept development. Further, the results suggest that curriculum and instruction design take into consideration the developmental progression of students' concept of energy. © 2005 Wiley Periodicals, Inc.
Globalisation and science education: Rethinking science education reforms
Authors: Carter Lyn
Published: March 2005

Like Lemke (J Res Sci Teach 38:296–316, 2001), I believe that science education has not looked enough at the impact of the changing theoretical and global landscape by which it is produced and shaped. Lemke makes a sound argument for science education to look beyond its own discourses toward those like cultural studies and politics, and to which I would add globalisation theory and relevant educational studies. Hence, in this study I draw together a range of investigations to argue that globalisation is indeed implicated in the discourses of science education, even if it remains underacknowledged and undertheorized. Establishing this relationship is important because it provides different frames of reference from which to investigate many of science education's current concerns, including those new forces that now have a direct impact on science classrooms. For example, one important question to investigate is the degree to which current science education improvement discourses are the consequences of quality research into science teaching and learning, or represent national and local responses to global economic restructuring and the imperatives of the supranational institutions that are largely beyond the control of science education. Developing globalisation as a theoretical construct to help formulate new questions and methods to examine these questions can provide science education with opportunities to expand the conceptual and analytical frameworks of much of its present and future scholarship. © 2005 Wiley‐Liss, Inc.
Prediction of fetal anemia in pregnancies with red‐cell alloimmunization: comparison of middle cerebral artery peak systolic velocity and amniotic fluid OD450
Authors: Bullock R. , Martin W. L. , Coomarasamy A. , Kilby M. D.
Published: March 2005

Objective

To compare the accuracy of Doppler velocimetry (middle cerebral artery peak systolic velocity, MCA‐PSV) and amniocentesis (amniotic fluid delta optical density 450 (OD450)) for the detection of fetal anemia against the gold standard of fetal blood sampling (FBS).

Methods

Thirty‐eight pregnancies were identified to be at risk of fetal anemia from immune causes between January 2000 and May 2002. In a cross‐sectional diagnostic accuracy study, MCA‐PSV and amniotic fluid delta OD450 values were plotted on reference charts and compared to an FBS obtained within the subsequent 7 days. Receiver–operating characteristics (ROC) curves were used and the area under the curve (AUC) calculated to compare the overall accuracy of the two tests. Sensitivity, specificity and likelihood ratios for positive (LR+) and negative (LR−) test results were generated for specific thresholds of MCA‐PSV and delta OD450.

Results

For MCA‐PSV (n = 38), the AUC was 0.71 (95% CI 0.57–0.85) and for amniotic fluid delta OD450 (n = 22) it was 0.68 (95% CI 0.49–0.87) compared with FBS within 7 days. Sensitivity, specificity and LR+, LR− for MCA‐PSV were 64%, 81%, 3.4 and 0.5, respectively, and 53%, 71%, 1.9 and 0.7 for amniotic fluid OD450, respectively.

Conclusion

MCA‐PSV and OD450 have similar test accuracy in detecting fetal anemia. MCA‐PSV is non‐invasive and therefore presents no risk of miscarriage or preterm labor and thus is a preferable method of screening for fetal anemia. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.
Deletion of PDE2, the gene encoding the high‐affinity cAMP phosphodiesterase, results in changes of the cell wall and membrane in Candida albicans
Authors: Jung Won Hee , Warn Peter , Ragni Enrico , Popolo Laura , Nunn Christopher D. , Turner Michael P. , Stateva Lubomira
Published: March 2005

A role for the cAMP‐dependent pathway in regulation of the cell wall in the model yeast Saccharomyces cerevisiae has recently been demonstrated. In this study we report the results of a phenotypic analysis of a Candida albicans mutant, characterized by a constitutive activation of the cAMP pathway due to deletion of PDE2, the gene encoding the high cAMP‐affinity phosphodiesterase. Unlike wild‐type strains, this mutant has an increased sensitivity to cell wall and membrane perturbing agents such as SDS and CFW, and antifungals such as amphotericin B and flucytosine. Moreover, the mutant is characterized by an altered sensitivity and a significantly reduced tolerance to fluconazole. The mutant's membrane has around 30% higher ergosterol content and the cell wall glucan was 22% lower than in the wild‐type. These cell wall and membrane changes are manifested by a considerable reduction in the thickness of the cell wall, which in the mutant is on average 60–65 nm, compared to 80–85 nm in the wild‐type strains as revealed by electron microscopy. These results suggest that constitutive activation of the cAMP pathway affects cell wall and membrane structure, and biosynthesis, not only in the model yeast S. cerevisiae but also in the human fungal pathogen C. albicans. Copyright © 2005 John Wiley & Sons, Ltd.
Amplification and expression of the TGF-α, EGF receptor and c-myc genes in four human oesophageal squamous cell carcinoma lines
Authors: Jones Gregory J. , Heiss Nina S. , Veale Robin B. , Thornley Alan L.
Published: March 2005

We have previously shown that four human oesophageal squamous cell carcinoma (SCC) cell lines secrete significant quantities of transforming growth factor alpha (TGF-α) in vitro. Three of these lines are known to produce supernumary low-affinity epidermal growth factor receptors (EGF-Rs). Using an125I-EGF compeitive binding assay and Scatchard analysis, we show that the fourth also overproduces low-affinity receptors. According to slot blot DNA analyses, the secretion of high levels of TGF-α is not associated with amplification of the TGF-α gene, and hyperproduction of the EGF-R is correlated with receptor gene amplification. Western blot analyses show that the c-Myc protein is overexpressed in two of the cell lines; and Southern and Northern blot analyses indicate that this overexpression occurs independently of c-myc gene amplification. Our results are consistent with an autocrine role for TGF-α and EGF-R in oesophageal carcinogenesis and support the possibility that c-myc overexpression may be required for the in vivo tumourigenicity of cells that produce high levels of TGF-α and the EGF-R.
Quality‐of‐life measurement in chronic heart failure: do we take account of the patient perspective?
Authors: Dunderdale Karen , Thompson David R. , Miles Jeremy N.V. , Beer Stephen F. , Furze Gill
Published: March 2005

The modern management of chronic heart failure has led to improved life expectancy, functioning and health‐related quality of life (HRQL). HRQL measures the effects of an illness or a treatment from the patient's perspective. It is now recognised that the patient's perspective is as legitimate and valid as the clinician's in monitoring health care outcomes. Although there are a number of quality‐of‐life measures, which can be separated into two types—generic and disease specific—many have been developed, with little or no account being taken of the patient's perspective. Because most of the widely used measures are not patient centred, they may lack sensitivity and specificity in determining those aspects of HRQL important to individual patients.

This paper reviews the use of quality‐of‐life assessment tools in the evaluation of patients with heart failure.
Echocardiographic evaluation of left ventricular end‐systolic elastance in the elderly
Authors: de Santis Domenico , Abete Pasquale , Testa Gianluca , Cacciatore Francesco , Galizia Gianluigi , Leosco Dario , Viati Luisa , Villano Vincenzo Del , Morte David Della , Mazzella Francesca , Ferrara Nicola , Rengo Franco
Published: March 2005

Background

The aging heart is characterized by structural changes, which are implicated in the development of left ventricular diastolic dysfunction. However, important changes in systolic function may also occur. Left ventricular end‐systolic elastance (Ees) is a major determinant of cardiac systolic function and ventricular—arterial interaction.

Aim

To evaluate left‐ventricular Ees in elderly subjects compared with adult control subjects.

Methods

We studied dilated (DA, n=14) and hypertensive (HA, n=21) cardiomyopathy patients, and both adult control (A, n=25; age 55.6±6.6 years) and elderly (E, n=25; age 76.3±7.1 years) subjects without clinical–instrumental evidence of cardiovascular disease. M‐mode, two‐dimensional, and pulsed Doppler echocardiogram were performed. Doppler‐derived indices of diastolic function were assessed and Ees was calculated by a modified single‐beat method.

Results

Ees was reduced in dilated cardiomyopathy (1.32±0.10 mm Hg/ml) and increased in hypertensive cardiomyopathy (3.12±0.33 mm Hg/ml) patients compared to age‐matched control subjects (1.96±0.26 mm Hg/ml; p<0.01 and p<0.05, respectively). More importantly, Ees was higher in the elderly (2.52±0.70 mm Hg/ml) than in the adult control group (p<0.05) and was linearly correlated with age (r2=0.639; p<0.0001).

Conclusion

Age‐related increase in Ees, together with diastolic dysfunction, may lead to aging heart decompensation.
Assessing the impact of fisheries on demersal fish assemblages of the Mauritanian continental shelf, 1987–1999, using dominance curves
Authors: Jouffre Didier , Inejih Cheikh A.
Published: March 2005

The assemblages of demersal fish and associated species of the Mauritanian continental shelf are characterized on the basis of annual trawl surveys conducted during the period 1987–1999. Species composition is dominated by exploited species (Dentex spp., Pagellus bellottii, and Octopus vulgaris). Dominance curves (Abundance Biomass Comparison plots) were used to evaluate the impact of fisheries, which have increased in magnitude over several decades. The diagnosis of a “stressed” assemblage seems to converge with the results of a similar study conducted off Senegal, but here there was no trend in impact during the period of study. The sensitivity of the present results to the various ways of considering the available taxonomic information is also analysed.
Indirect economic indicators in bio-economic fishery models: agricultural price indicators and fish stocks in Lake Victoria
Authors: Simonit Silvio , Perrings Charles
Published: March 2005

We consider the potential for using prices as leading indicators of changes in stocks and yields in the freshwater capture fishery in Lake Victoria. Fertilizer run-off from agricultural land is a major cause of nutrient loading, along with soil erosion, atmospheric deposition, and point pollution from industrial and domestic affluent. The interactions between fertilizer applications, water quality, fish stocks, and yields are modelled in order to predict the effect of changes in the price of fertilizers on the fishery. The fishery model includes a measure of Chl a concentration (a proxy for phytoplankton density). The consequences of changes in Chl a concentration for fish stocks are modelled using Ecopath. We show that fertilizer prices are effective leading indicators of changes in fish biomass and yield.
Post-anthesis nitrogen accumulation and distribution among grains in spring wheat spikes
Authors: ANDERSSON A. , JOHANSSON E. , OSCARSON P.
Published: March 2005

Knowledge of nitrogen accumulation to the grains is of great importance for identifying breeding and growing strategies to improve cereal yield and quality. The aim of this study was to investigate post-anthesis N translocation in the spike and into different spikelets of two cultivars of spring wheat (Triticum aestivum L.) grown to maturity in solution culture. Sport (short grain filling time, low yield and high grain protein concentration) and WL (normal grain filling time, high yield and low protein concentration) were the cultivars used. Plants received stepwise declining rates of N on a daily basis, until 109 days after planting (DAP). Anthesis for cv. Sport was 92 DAP and for cv. WL 78 DAP. On seven occasions (from anthesis in cv. WL until maturity), 15N was given to selected groups of plants for 4 days. Then these plants were sampled and separated into plant parts. Spikelets and grains were separated according to spikelet position. Plant parts were weighed and analysed for N and 15N.

The N concentration in the grains was uniform for the spikelets in cv. WL but differed in cv. Sport. Final N concentration in a spikelet position was obtained at 126 DAP in cv. Sport and 112 DAP in cv. WL and was constant to the end of experiment at 154 DAP in cv. Sport and 147 DAP in cv. WL. A positive correlation between % atom excess 15N to spikelet position numbered from the base of the spike was exhibited in the lowermost part of the spike just after anthesis. Later, during grain filling, a negative correlation between % atom excess 15N to spikelet position was exhibited (−0·991 P=0·000). A positive correlation between % atom excess 15N to grain weight in the top of the spike was exhibited. Accumulation of 15N proceeded 14 days longer in the lowermost fertile spikelets than in the uppermost spikelets. It was concluded that the duration of N accumulation in the spikelets was dependent on spikelet position and uppermost spikelets had a shorter N accumulation period and contained lighter grains than lowermost spikelets.
Agronomic performance of maize cultivars representing three decades of breeding in the Guinea Savannas of West and Central Africa
Authors: KAMARA A. Y. , MENKIR A. , FAKOREDE M. A. B. , AJALA S. O. , BADU-APRAKU B. , KUREH I.
Published: March 2005

Maize improvement at the International Institute of Tropical Agriculture (IITA), which began in the 1970s, built on the germplasm and experience of earlier years. The main breeding emphasis was to develop maize cultivars and hybrids with high yield potential and durable resistance to diseases and pests with specific adaptation to the different agro-ecological zones of West and Central Africa. Over the years, open-pollinated cultivars have been developed with different levels of resistance to biotic and abiotic stresses. Identification of the factors that contributed to improvements in the maize cultivars developed during the past decades may be useful to sustain the genetic gain from selection in the future. A study was conducted to quantify genetic gains in yield and associated traits of open pollinated maize cultivars released from 1970 to 1999 in the West African savannas. The genetic gain in grain yield was 0·41% per year and seems to be associated with increases in total biomass and kernel weight, and reductions in plant height and days to flowering (anthesis and silking). There was no significant change in harvest index of the cultivars.
Diallel analysis of maize lines with contrasting responses to applied nitrogen
Authors: MEDICI L. O. , PEREIRA M. B. , LEA P. J. , AZEVEDO R. A.
Published: March 2005

Six S5 lines of maize, previously identified as having contrasting responses to nitrogen (N) supply, were used to carry out a complete series of diallel crosses. The resulting 15 hybrids were grown in a field at two N levels. The general combining ability (GCA) and specific combining ability (SCA) were estimated using the method 4, model I analysis of Griffing for grain yield kernel weight, grain number, harvest index, green leaf number, ear leaf area, N utilization efficiency, total plant N, grain N content, anthesis-silking interval, chlorophyll content and prolificacy. For the majority of the traits, GCA was more important than SCA and there was an increase of non-additive effects under low N. Significant interactions were observed between GCA and N levels for grain yield, grain number and chlorophyll content, indicating the selection of different lines for each N level. The lines with the largest effects of N supply per se on grain yield, were those with the largest effects of GCA for this trait. This association indicates that the response of the lines to N supply, should be considered in breeding programmes in order to achieve acceptable hybrids for environments with both high and low N.
Growth stage-specific application of slurry and mineral N to oilseed rape, wheat and barley
Authors: SIELING K.
Published: March 2005

Farmers commonly apply slurry when soil conditions are suitable for spreading. In order to improve slurry nitrogen (N) use efficiency, effects of split application of pig slurry according to the crop N demand on yield were tested in 1994/95–2001/02. The crop rotation was winter oilseed rape (OSR) – winter wheat – winter barley. N was applied as pig slurry or as mineral N fertilizer (each of 0, 40 or 80 kg N/ha, total N amount: 0–240 kg N/ha) at three dates. Each year, the treatments occurred in all three crops of the rotation and were located on the same plots. On average, mineral N fertilizer led to higher grain yields in all crops (+0·33 t/ha in OSR, +0·57 t/ha in wheat, and +0·20 t/ha in barley) compared with slurry application, presumably due to a slower N mineralization of the organic fraction. However, the large year to year variation resulted in high error estimates, leading to no significant differences in yield. Taking only the ammonium amount of the slurry into account, there was no significant difference in yield between the two N sources. Yield potential was similar in both slurry and mineral N treatments, but higher N amounts were necessary on the slurry plots. Therefore, slurry N-use efficiency (NUE) remained lower than that of mineral N. However, compared with a single dose, growth-specific slurry application according to the crop demand, as made with mineral N fertilizers, increased NUE.
Edited out of contemporary theoretical discourse yet central to the way we think about architecture.
Authors: Hale Jonathan
Published: March 2005

This conference set out to address the rise, fall and possible futures of the problematic and controversial term ‘primitive’. Taking place over two days in September 2004 at the Welsh School of Architecture in Cardiff (hosted by the Architectural History and Theory Group), it aimed to attract an interdisciplinary audience and included a range of keynote speakers drawn from both academia and practice. Selected papers from the proceedings will be published in book form by Routledge in 2005.
A Primitive exchange: on rhetoric and architectural symbol
Authors: Frith Stephen
Published: March 2005

In relating stories about origins that recall an idealized ‘Primitive’ condition, Vitruvius seeks legitimacy for judgement about architecture. At issue is the problem of authority, and Vitruvius is anxious about authority, and about order. Vitruvius' audience for his story of the Primitive dwelling, as for the rest of his treatise, the Ten Books on Architecture, is the emperor Octavian, introduced in the dedicatory preface as ‘imperator Caesar.’ His book to Caesar asserts a commonplace among rhetoricians, that authority is sought in a distant past, and in exemplars, useful precedents that promise a perfect work. ‘Décor,’ writes Vitruvius, ‘demands the faultless ensemble of a work composed, in accordance with precedent, of approved details. It obeys convention, which in Greek is called thematismos, or custom or nature’ (trans Granger, 1983, I.2.5). The task of the orator was to ‘demonstrate’ (demonstratio) that authority, and so for architecture, in his mythmaking and concern to demonstrate the truth of his opinions, Vitruvius establishes that the task of architecture is the representation of order.
Baptism and sacrifice: cosmogony as private ontology
Authors: Temple Nicholas
Published: March 2005

Questions concerning the significance and meaning of sacrifice in our secular age, whether in the form of a ritualized or purely contemplative construct, lay bare much that is problematic and troubling about modern consciousness. This paper examines the mortuary significance of baptism and its influence on architecture, drawing comparison between Early Christian and modern views of sacrifice. By referring to key theological writings, the study considers the baptistery as a site of human conversion where the search for redemption unfolds as both a cosmological and mytho-historical drama. The investigation distinguishes between the literal meaning of sacrifice and its more complex Platonic-Christian symbolism, the latter defining the nature of human piety and ultimate spiritual immortality. The study concludes with an examination of the baptismal font at St Peter's in Klippan. It asks whether this seminal work attests to a continuity of symbolic meanings or whether it is the product of hermetic thought.
Musiktherapie bei chronischem Tinnitus
Authors: Argstatter Heike , Nickel Anne Kathrin , Rupp André , Hoth Sebastian , Bolay Hans Volker
Published: March 2005

Zusammenfassung. Das Deutsche Zentrum für Musiktherapieforschung (Viktor Dulger Insitut) DZM e.V. führt in Kooperation mit den Kliniken Neurologie und HNO der Universität Heidelberg eine Studie zur Entwicklung und Überprüfung einer neuartigen musiktherapeutischen Behandlungsmethode bei chronischem Tinnitus durch. Dabei soll die Wirksamkeit der musiktherapeutischen Behandlung hinsichtlich der subjektiven und objektiven Verbesserung der Symptomatik überprüft werden. Geplant ist ein modulares Vorgehen, bei dem zunächst für jeden Patienten ein individueller tinnitus-ähnlicher Klang erstellt wird. In einem zweiten Schritt erfolgt die musiktherapeutische Behandlung, in der dieser Klang aktiv und/oder rezeptiv eingesetzt wird. Um die Effektivität der Behandlung zu überprüfen sollen vor Beginn und nach Ende der Therapie Kontrollmessungen mit psychologischen (insbesondere Tinnitus-Fragebogen nach Goebel & Hiller, 1998 ) und bildgebenden Verfahren (Magnetenzephalographie, MEG) erfolgen.
Entwicklung eines ambulanten psychosozialen Nachsorgeangebotes für onkologische Patienten
Authors: Weiss Katrin , Buttstädt Marianne , Singer Susanne , Schwarz Reinhold
Published: March 2005

Zusammenfassung. Eine Krebserkrankung greift in vielfältiger Weise in das familiäre Beziehungsgefüge ein. Die Belastungen der Kinder durch eine schwere Erkrankung der Eltern werden dabei oft unterschätzt. In Abhängigkeit vom Vorhandensein oder Fehlen protektiver Faktoren entwickeln die Kinder chronisch kranker Eltern häufiger depressive Symptome, Verhaltensstörungen und Ängste als die Kinder gesunder Eltern. Durch eine angemessene Kommunikation über die Erkrankung und deren Folgen können Verarbeitungsprozesse bei den Kindern gefördert und der Entwicklung psychischer Auffälligkeiten entgegenwirkt werden. Vielen Krebskranken fällt es jedoch schwer, über Probleme im Zusammenhang mit der Erkrankung zu sprechen. Es ist deshalb Anliegen des von uns entwickelten Gestaltungskurses, die Ausdrucksmöglichkeiten betroffener Eltern zu erweitern, Krankheitsverarbeitung zu fördern sowie Kommunikationsprozesse in den Familien anzuregen. Der Gestaltungskurs enthält stützende und kreativitätsanregende Elemente und gliedert sich in die drei aufeinander aufbauenden Phasen: Lernen, Transformieren, Produzieren. Im dritten Kursabschnitt gestaltet jeder Teilnehmer ein persönliches Buch, welches als vermittelndes Medium Gespräche erleichtern soll.
mPER1‐mediated nuclear export of mCRY1/2 is an important element in establishing circadian rhythm
Authors: Loop Susanne , Katzer Mathias , Pieler Tomas
Published: March 2005

Receptor‐mediated nucleocytoplasmic transport of clock proteins is an important, conserved element of the core mechanism for circadian rhythmicity. A systematic analysis of the nuclear export characteristics for the different murine period (mPER) and cryptochrome (mCRY) proteins using Xenopus oocytes as an experimental system demonstrates that all three mPER proteins, but neither mCRY1 nor mCRY2, are exported if injected individually. However, nuclear injection of heterodimeric complexes that contain combinations of mPER and mCRY proteins shows that mPER1 serves as an export adaptor for mCRY1 and mCRY2. Functional analysis of dominant‐negative mPER1 variants designed either to sequester mPER3 to the cytoplasm or to inhibit nuclear export of mCRY1/2 in synchronized, stably transfected fibroblasts suggests that mPER1‐mediated export of mCRY1/2 defines an important new element of the core clock machinery in vertebrates.
Supporting Visual Queries on Medium-Sized Node–Link Diagrams
Authors: Ware Colin , Bobrow Robert
Published: March 2005

For reasons of clarity, a typical node–link diagram statically displayed on paper or a computer screen contains fewer than 30 nodes. However, many problems would benefit if far more complex information could be diagrammed. Following Munzner et al., we suggest that with interactive diagrams this may be possible. We describe an interactive technique whereby a subset of a larger network diagram is highlighted by being set into oscillatory motion when a node is selected with a mouse. The subset is determined by a breadth first search of the underlying graph starting from the selected node. This technique is designed to support visual queries on moderately large node-link diagrams containing up to a few thousand nodes. An experimental evaluation was carried out with networks having 32, 100, 320, 1000, and 3200 nodes respectively, and with four highlighting techniques: static highlighting, motion highlighting, static+ motion highlighting, and none. The results show that the interactive highlighting methods support rapid visual queries of nodes in close topological proximity to one another, even for the largest diagrams tested. Without highlighting, error rates were high even for the smallest network that was evaluated. Motion highlighting and static highlighting were equally effective. A second experiment was carried out to evaluate methods for showing two subsets of a larger network simultaneously in such a way that both are clearly distinct. The specific task was to determine if the two subsets had nodes in common. The results showed that this task could be performed rapidly and with few errors if one subset was highlighted using motion and the other was highlighted using a static technique. We discuss the implications for information visualization.
Universality in a class of Q-ball solutions: An analytic approach
Authors: Ioannidou T. A. , Kouiroukidis A. , Vlachos N. D.
Published: March 2005

The properties of Q-balls in the general case of a sixth order potential have been studied using analytic methods. In particular, for a given potential, the initial field value that leads to the soliton solution has been derived and the corresponding energy and charge have been explicitly evaluated. The proposed scheme is found to work reasonably well for all allowed values of the model parameters.
Shock wave propagation in dissociating low-Z liquids: D2
Authors: Belonoshko A. B. , Rosengren A. , Skorodumova N. V. , Bastea S. , Johansson B.
Published: March 2005

We present direct molecular dynamics simulations of shock wave propagation in liquid deuterium for a wide range of impact velocities. The calculated Hugoniot is in perfect agreement with the gas-gun data as well as with the most recent experimental data. At high impact velocities we observe a smearing of the shock wave front and propagation of fast dissociated molecules well ahead of the compressed region. This smearing occurs due to the fast deuterium dissociation at the shock wave front. The experimental results are discussed in view of this effect.
Velocity-map imaging study of the photodissociation of acetaldehyde
Authors: Cruse H. A. , Softley T. P.
Published: March 2005

Velocity-map imaging studies are reported for the photodissociation of acetaldehyde over a range of photolysis wavelengths (317.5–282.5 nm). Images are obtained for both the HCO and CH3 fragments. The mean rotational energy of both fragments increases with photodissociation energy, with a lesser degree of excitation in the CH3 fragment. The CH3 images demonstrate that the CH3 fragments are rotationally aligned with respect to the recoil direction and this is interpreted, and well modeled, on the basis of a propensity for forming CH3 fragments with M∼K, where M is the projection of the rotational angular momentum along the recoil direction. The origin of the CH3 rotation is conserved motion from the torsional and methyl-rocking modes of the parent molecule. Nonstatistical vibrational distributions for the CH3 fragment are obtained at higher energies.
Analysis of failures in semiconductor lasers subjected to accelerated aging
Authors: Salvatore R. A. , Yang F.
Published: March 2005

An analysis technique is developed for the purpose of determining which semiconductor laser parameter is responsible for degradation. The technique allows one to distinguish between the two modes of degradation: (1) a reduction in electrical carrier injection efficiency or (2) an increase in optical loss. In the case of increasing optical loss, one can determine where longitudinally along the waveguide this degraded optical loss is occurring. Experimentally, we apply the technique to an earlier generation of high-power, single-mode 14XX-nm pump lasers under various accelerated aging conditions.
Influence of ion implantation on the magnetic properties of thin FeCo films
Authors: Gupta Ratnesh , Han K.-H. , Lieb K. P. , Müller G. A. , Schaaf P. , Zhang K.
Published: March 2005

Modifications of 73-nm-thick polycrystalline FeCo films by magnetic-field-assisted implantation of Ne, Xe, and Au ions have been investigated. For magnetic characterization, the longitudinal magneto-optic Kerr effect and magnetic force microscopy (MFM) in the remanent state have been used, while structural information has been gained from glancing-angle x-ray diffraction and Rutherford backscattering spectroscopy. The irradiated films show a soft-magnetic behavior with large magnetic anisotropy. The Ne ions initially induce an increasing coercivity, possibly due to radiation defects accumulated during the ion implantation, while higher Ne fluences anneal out the defects and reduce the coercivity. For the heavy ions the deposited energy density is high enough to reduce the coercivity at small fluences and then to increase it slightly for increasing fluence. Correlations between the magnetic anisotropy, coercivity and the ion species and fluence have been established. The MFM pictures feature the largest changes in the case of Au ions. The magnetic anisotropy reflects the interplay between magnetocrystalline and magnetostrictive forces. For heavier ions and large fluences, the direction of the in-plane magnetic easy axis follows the orientation of the external magnetic field present during implantation.
Optical microfabrication of highly reflective volume Bragg gratings
Authors: Hsiao Vincent K. S. , Lin Tzu-Chau , He Guang S. , Cartwright Alexander N. , Prasad Paras N. , Natarajan Lalgudi V. , Tondiglia Vincent P. , Bunning Timothy J.
Published: March 2005

An approach for fabricating wide-bandwidth and highly reflective Bragg grating structures with the technique of holographic photopolymerization of a liquid crystal (LC) polymer composite is presented. The key to this fabrication method that distinguishes it from previous methods is the use of a nonreactive solvent, acetone, to dissolve the photoinitiator and coinitiator in an acrylate monomer/LC mixture. The addition of acetone results in the creation of controllable periodic voids inside the thin film after the acetone evaporates. Peak reflectivity as high as 80% and a broad reflection bandwidth of 80nm were observed in the reflection gratings formed with acetone present in the starting mixture. It was estimated from a fit to the experimental data that the resulting index mismatch was approximately 0.2; consistent with the presence of air voids. It is determined that tunable wavelength, diffraction efficiency, and bandwidth of reflection notches can be achieved by backfilling with fluids of different refractive indices.
Light-induced absorption and its relaxation under illumination of continuous wave ultraviolet light in Mn-doped near-stoichiometric LiNbO3
Authors: Liu Youwen , Kitamura Kenji , Takekawa Shunji , Ravi Ganesan , Nakamura Masaru , Hatano Hideki
Published: March 2005

The steady-state light-induced absorption and the temporal relaxation behavior under illumination of cw ultraviolet light in Mn-doped near-stoichiometric LiNbO3 with different crystal compositions are investigated. The ultraviolet-light-induced absorption has been assigned to small polarons NbLi4+ by measuring the absorption spectra at room temperature. The dependences of relaxation behaviors (time constant and stretching factor) of light-induced absorption on various illumination conditions (intensity, polarization) and temperature are presented, which are very different from those observed in Fe-doped LiNbO3 illuminated with highly intense light pulse, though the temporal relaxation follows the same stretched-exponential decay behavior in both cases. The results are explained reasonably by using the model of distance-dependent electron transition probabilities between localized deep traps and small polarons without any additional assumptions, and discussed to tailor doped near-stoichiometric LiNbO3 crystals for two-color holographic recording with cw laser light.
Synthesis of taperlike Si nanowires with strong field emission
Authors: Chueh Y. L. , Chou L. J. , Cheng S. L. , He J. H. , Wu W. W. , Chen L. J.
Published: March 2005

Taperlike Si nanowires (SiNWs) have been synthesized by annealing of high-density FeSi2 nanodots on (001)Si at 1200°C in a N2 ambient. The tip regions of SiNWs are about 5–10nm in diameter. The average length of the SiNWs is about 6μm with aspect ratios as high as 150–170. A growth model based on oxide-assisted growth is proposed. The taperlike morphology may be caused by the passivation of the SiO2 coating layer, which results in the different levels of absorption of SiO along the length of the nanowires. The SiNWs exhibit a turn-on field of 6.3–7.3V∕μm and a threshold field of 9–10V∕μm. The excellent field emission characteristics are attributed to the taperlike geometry of the crystalline Si nanowires.
Initial states and decoherence of histories
Authors: Scherer Artur , Soklakov Andrei N.
Published: March 2005

We study decoherence properties of arbitrarily long histories constructed from a fixed projective partition of a finite dimensional Hilbert space. We show that decoherence of such histories for all initial states that are naturally induced by the projective partition implies decoherence for arbitrary initial states. In addition we generalize the simple necessary decoherence condition [Scherer et al., Phys. Lett. A 326, 307 (2004)] for such histories to the case of arbitrary coarse graining.
Gene regulatory networks for development
Authors: Levine Michael , Davidson Eric H.
Published: March 2005

The genomic program for development operates primarily by the regulated expression of genes encoding transcription factors and components of cell signaling pathways. This program is executed by cis-regulatory DNAs (e.g., enhancers and silencers) that control gene expression. The regulatory inputs and functional outputs of developmental control genes constitute network-like architectures. In this PNAS Special Feature are assembled papers on developmental gene regulatory networks governing the formation of various tissues and organs in nematodes, flies, sea urchins, frogs, and mammals. Here, we survey salient points of these networks, by using as reference those governing specification of the endomesoderm in sea urchin embryos and dorsal–ventral patterning in the
Drosophila
embryo.
Regulation of hematopoietic stem cell agingin vivoby a distinct genetic element
Authors: Geiger Hartmut , Rennebeck Gabriela , Van Zant Gary
Published: March 2005

Until recently, stem cells were thought to be endowed with unlimited self-renewal capacity and, thus, assumed exempt from aging. But accumulating evidence over the past decade compellingly argues that a measurable and progressive replicative impairment in the hematopoietic, intestinal, and muscle stem cell activity exists from adulthood to old age, resulting in a decline in stem cell function and rendering stem cell aging as the possible link between cellular aging and organismal aging. By using a previously uncharacterized congenic animal model to study genetic regulation of hematopoietic stem cell aging, we have demonstrated definitively that a locus on murine chromosome 2 regulates hematopoietic stem cell aging. In addition to demonstrating that hematopoietic stem cell aging is regulated by a distinct genetic element, experimental evidence links the response of hematopoietic stem cells to DNA double-strand breaks to cellular aging, suggesting DNA integrity influences stem cell aging.
An interpolation theorem for Hilbert spaces with Nevanlinna-Pick kernel
Authors: Bøe Bjarte
Published: March 2005

We prove an interpolation theorem for Hilbert spaces of analytic functions that have the Nevanlinna-Pick property. This result applies to Dirichlet and Dirichlet-type spaces, and in particular a short proof of the theorem by Marshall-Sundberg on interpolating sequences is obtained.
The Artin-Stafford gap theorem
Authors: Smoktunowicz Agata
Published: March 2005

Let

K
K

be an algebraically closed field, and let

R
R

be a finitely graded

K
K

-algebra which is a domain. We show that

R
R

cannot have Gelfand-Kirillov dimension strictly between

2
2

and

3
3

.
Bases of the contact-order filtration of derivations of Coxeter arrangements
Authors: Terao Hiroaki
Published: March 2005

In a recent paper, we constructed a basis for the contact-order filtration of the module of derivations on the orbit space of a finite real reflection group acting on an

ℓ
\ell

-dimensional Euclidean space. Recently M. Yoshinaga constructed another basis for the contact-order filtration. In this note we give an explicit formula relating Yoshinaga’s basis to the basis we constructed earlier. The two bases turn out to be equal (up to a constant matrix).
Relations approximated by continuous functions
Authors: Holá L’. , McCoy R.
Published: March 2005

Let

X
X

be a Tychonoff space, let

C
(
X
)

C(X)

be the space of all continuous real-valued functions defined on

X
X

and let

C
L
(
X
×
R
)

CL(X \times R)

be the hyperspace of all nonempty closed subsets of

X
×
R

X\times R

. We prove the following result. Let

X
X

be a locally connected, countably paracompact, normal

q
q

-space without isolated points, and let

F
∈
C
L
(
X
×
R
)

F \in CL(X \times R)

. Then

F
F

is in the closure of

C
(
X
)

C(X)

in

C
L
(
X
×
R
)

CL(X \times R)

with the locally finite topology if and only if

F
F

is the graph of a cusco map. Some results concerning an approximation in the Vietoris topology are also given.
Composition operators on Banach function spaces
Authors: Kumar Rajeev , Kumar Romesh
Published: March 2005

We study the boundedness and the compactness of composition operators on some Banach function spaces such as absolutely continuous Banach function spaces on a

σ
\sigma

–finite measure space, Lorentz function spaces on a

σ
\sigma

–finite measure space and rearrangement invariant spaces on a resonant measure space. In addition, we study some properties of the spectra of a composition operator on the general Banach function spaces.
Boundedness of the first eigenvalue of the 𝑝-Laplacian
Authors: Matei Ana-Maria
Published: March 2005

We prove that for any

p
>
1

p>1

, any compact manifold of three or more dimensions carries Riemannian metrics of volume one with the first eigenvalue of the

p
p

-Laplacian arbitrarily large.
Decomposable form equations without the finiteness property
Authors: Chen Zhihua , Ru Min
Published: March 2005

Let

K
K

be a finitely generated (but not necessarily algebraic) extension field of

Q

{\mathbb {Q}}

. Let

F
(

X

)
=
F
(

X

1

,
…
,

X

m

)

F({\mathbf {X}})=F(X_{1}, \dots , X_{m})

be a form (homogeneous polynomial) in

m
≥
2

m \ge 2

variables with coefficients in

K
K

, and suppose that

F
F

is decomposable (i.e., that it factorizes into linear factors over some finite extension of

K
K

). We say that

F
F

has the finiteness property over

K
K

if for every

b
∈

K

∗

b \in K^{*}

(here

K

∗

K^{*}

denotes the set of non-zero elements in

K
K

) and for every subring

R
R

of

K
K

which is finitely generated over

Z

{\mathbb {Z}}

, the equation

F
(

x

)
=
b
 
 
 
in
 
 
 
 

x

=
(

x

1

,
…
,

x

m

)
∈

R

m

\begin{equation*} F({\mathbf {x}})=b ~~~\text {in} ~~~~{\mathbf {x}}=(x_{1}, \dots , x_{m})\in R^{m}\end{equation*}

has only finitely many solutions. This paper proves the following result: Let

F
F

be a decomposable form in

m
≥
2

m \ge 2

variables with coefficients in

K
K

, which factorizes into linear factors over

K
K

. Let

L

{\mathcal {L}}

denote a maximal set of pairwise linearly independent linear factors of

F
F

. If

F
F

has the finiteness property over

K
K

, then

#

L

>
2
(
m
−
1
)

\#{\mathcal {L}} > 2(m-1)

.
Global existence for a class of triangular parabolic systems on domains of arbitrary dimension
Authors: Le Dung , Nguyen Toan
Published: March 2005

A class of triangular parabolic systems given on bounded domains of

R

n

\mathbb {R}^n

with arbitrary

n
n

is investigated. Sufficient conditions on the structure of the systems are found to assure that weak solutions exist globally.
On identities in groups of fractions of cancellative semigroups
Authors: Ivanov S. , Storozhev A.
Published: March 2005

To solve two problems of Bergman stated in 1981, we construct a group

G
G

such that

G
G

contains a free noncyclic subgroup (hence,

G
G

satisfies no group identity) and

G
G

, as a group, is generated by its subsemigroup that satisfies a nontrivial semigroup identity.
A topological Paley-Wiener property for locally compact groups
Authors: Kaniuth Eberhard , Lau Anthony , Schlichting Günter
Published: March 2005

We investigate a certain topological Paley-Wiener property and show, for instance, that compact-free nilpotent groups and simply connected solvable groups share this property.
A note on Hardy-type inequalities
Authors: Gao Peng
Published: March 2005

We use a theorem of Cartlidge and the technique of Redheffer’s “recurrent inequalities" to give some results on inequalities related to Hardy’s inequality.
SUMO Represses Transcriptional Activity of theDrosophilaSoxNeuro and Human Sox3 Central Nervous System–specific Transcription Factors
Authors: Savare Jean , Bonneaud Nathalie , Girard Franck
Published: March 2005

Sry high mobility group (HMG) box (Sox) transcription factors are involved in the development of central nervous system (CNS) in all metazoans. Little is known on the molecular mechanisms that regulate their transcriptional activity. Covalent posttranslational modification by small ubiquitin-like modifier (SUMO) regulates several nuclear events, including the transcriptional activity of transcription factors. Here, we demonstrate that SoxNeuro, an HMG box-containing transcription factor involved in neuroblast formation in Drosophila, is a substrate for SUMO modification. SUMOylation assays in HeLa cells and Drosophila S2 cells reveal that lysine 439 is the major SUMO acceptor site. The sequence in SoxNeuro targeted for SUMOylation, IKSE, is part of a small inhibitory domain, able to repress in cis the activity of two adjacent transcriptional activation domains. Our data show that SUMO modification represses SoxNeuro transcriptional activity in transfected cells. Overexpression in Drosophila embryos of a SoxN form that cannot be targeted for SUMOylation strongly impairs the development of the CNS, suggesting that SUMO modification of SoxN is crucial for regulating its activity in vivo. Finally, we present evidence that SUMO modification of group B1 Sox factors was conserved during evolution, because Sox3, the human counterpart of SoxN, is also negatively regulated through SUMO modification.
Genome-wide Analysis of the Functions of a Conserved Surface on the Corepressor Tup1
Authors: Green Sarah R. , Johnson Alexander D.
Published: March 2005

The general transcriptional repressor Tup1 is responsible for the regulation of a large, diverse set of genes in Saccharomyces cerevisiae, and functional homologues of Tup1 have been identified in many metazoans. The crystal structure for the C-terminal portion of Tup1 has been solved and, when sequences of Tup1 homologues from fungi and metazoans were compared, a highly conserved surface was revealed. In this article, we analyze five point mutations that lie on this conserved surface. A statistical analysis of expression microarrays demonstrates that the mutant alleles are deficient in the repression of different subsets of Tup1-regulated genes. We were able to rank the mutant alleles of TUP1 based on the severity of their repression defects measured both by the number of genes derepressed and by the magnitude of that derepression. For one particular class of genes, the mutations on the conserved surface disrupted recruitment of Tup1 to the repressed promoters. However, for the majority of the genes derepressed by the Tup1 point mutants, recruitment of Tup1 to the regulated promoters is largely unaffected. These mutations affect the mechanism of repression subsequent to recruitment of the complex and likely represent a disruption of a mechanism that is conserved in fungi and metazoans. This work demonstrates that the evolutionarily conserved surface of Tup1 interacts with two separate types of proteins—sequence-specific DNA-binding proteins responsible for recruiting Tup1 to promoters as well as components that are likely to function in a conserved repression mechanism.