bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructure of the annual cycle of female sperm storage in spermathecae of the torrent salamander, Rhyacotriton variegatus (Amphibia: Rhyacotritonidae)
Authors: Sever David M. , Tait Cynthia K. , Diller Lowell V. , Burkholder Laura 
Published: May 2004

AbstractThis study is the first report on the ultrastructure of the sperm storage glands (spermathecae) in the salamander Rhyacotriton variegatus. The population studied is associated with cold‐water, rocky streams of the redwood (Sequoia) zone in northern California. Males possess sperm in their vasa deferentia and undergo spermiation throughout the year, but mating is seasonal. Most females with large, vitellogenic follicles (2.0–3.9 mm mean dia.) collected from February–June contain sperm in their spermathecae, although some females with large follicles lack sperm. Other mature‐size females collected during this period have small ovarian follicles (0.9–1.2 mm mean dia.) and lack stored sperm. All females collected from September–November have small follicles (0.6–1.6 mm mean dia.) and lack sperm, except in one instance in which a female collected in November had a small amount of degraded sperm, apparently retained from the previous breeding season. The spermathecae consist of simple tubulo‐alveolar glands in which the neck tubules produce a mucoid secretory product, and the distal bulbs, where sperm are stored, contain secretory vacuoles of uniform density that stain positively for glycosaminoglycans. In specimens containing sperm, some bulbs have abundant sperm and others lack sperm, but the ultrastructure is similar in both conditions. The acini contain columnar epithelial cells with wide intercellular canaliculi, and a merocrine process releases the secretion. Spermiophagy occurs. In specimens from spring and summer with small ovarian follicles, the neck tubules are similar to those of breeding females, but the distal bulbs are reduced to cords of cells lacking a discernible lumen. Secretory activity in the distal bulbs is initiated in the fall. Spermathecae of R. variegatus are most similar to those of a stream‐dwelling plethodontid, Eurycea cirrigera. J Morphol. 261:1–17, 2004. © 2004 Wiley‐Liss, Inc.
Trichoderma enzymes promote Fibrobacter succinogenes S85 adhesion to, and degradation of, complex substrates but not pure cellulose
Authors: Morgavi Diego P , Beauchemin Karen A , Nsereko Victor L , Rode Lyle M , McAllister Tim A , Wang Yuxy 
Published: May 2004

AbstractThe effects of an enzyme preparation from Trichoderma longibrachiatum (TE) on adhesion and growth of the fibrolytic rumen bacterium Fibrobacter succinogenes S85 was studied to gain a better understanding of the action of feed enzyme additives on fibre digestion by ruminants. Adhesion experiments were performed on crystalline cellulose, corn silage and alfalfa hay. Adhesion of F succinogenes to cellulose was negatively related to the concentration of TE (p < 0.05). At the highest concentration used, TE reduced adhesion to cellulose from 65 to 39%. For corn silage and alfalfa hay, TE stimulated adhesion at low levels (p < 0.05) but this effect was lost at higher levels. Culture experiments were performed on crystalline cellulose and corn silage. The presence of TE in media containing cellulose failed to increase substrate disappearance or gas production although it increased numbers of non‐adherent bacteria (p < 0.05). When corn silage was used, the addition of TE increased NDF disappearance (p < 0.05) at 24 and 48 h (33 and 52% in controls versus 53 and 65% in TE treatments). Growth rate and gas production were also stimulated (p < 0.05). We conclude that, for cellulose, the hydrolytic enzymes in TE obstructed available binding sites decreasing bacterial adherence. Fibrobacter succinogenes digested cellulose efficiently and addition of exogenous cellulases did not further increase substrate disappearance. However, for complex plant substrates, low concentration of TE increased bacterial adhesion and plant (corn) fiber degradation. For the Department of Agriculture and Agri‐Food, Government of Canada, © Minister of Public Works and Government Services Canada 2004. Published for SCI by John Wiley & Sons, Ltd.
A high‐resolution tunable fiber Bragg grating filter
Authors: Tay C. M. , Tan K. M. , Tjin S. C. , Chan C. C. , Ngo N. Q. , Dong X. Y. 
Published: May 2004

AbstractA tunable fiber Bragg grating (FBG) filter with a tuning resolution of less than one picometer (pm) is demonstrated. The FBG is embedded in carbon‐fiber composite material, which is bent by using a simple mechanical setup. A tuning range of 2 nm and repeatability of less than 0.4% are obtained. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 89–92, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20217
Simulation of ultra‐wideband indoor propagation
Authors: Attiya A. M. , Safaai‐Jazi A. 
Published: May 2004

AbstractA comprehensive simulation of ultra‐wideband signal propagation in indoor environments is presented. The simulation is based on time‐domain electromagnetic modeling of transmitting and receiving antennas and the analysis of wave propagation through indoor channels using the time‐domain uniform theory of diffraction. The antennas are a pair of TEM horns which are modeled as arrays of vee dipoles. The analysis of these antennas is performed directly in the time domain, without the need for transforming the solutions from the frequency domain to the time domain. The frequency dependence of materials utilized in the structure on the indoor channel is accounted for in the channel simulation. The simulation results are compared with the corresponding measured results. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 103–108, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20221
Novel ultra‐wideband discone antenna
Authors: Kim Jinu , Park Seong‐Ook 
Published: May 2004

AbstractA double‐discone antenna for an ultra‐wideband frequency scan is presented. An exquisite assembly of two inverse‐feeding discone antennas shows a 30:1 broad bandwidth with VSWR below 2.5 and an omnidirectional radiation pattern. These features make the proposed antenna very suitable for both the UWB system antenna and the wideband scan antenna. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 113–115, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20224
Genetic approach to prenatal diagnosis in urea cycle defects
Authors: Häberle Johannes , Koch Hans Georg 
Published: May 2004

AbstractObjectiveTo demonstrate the feasibility of prenatal diagnosis by molecular genetics in all urea cycle defects in order to improve and standardize the current approaches.MethodsDeceased index patients who had suffered from a urea cycle disorder were investigated for mutations of the biochemically most likely affected gene. If no material of index patients was available, parental DNA was studied for obligate carrier status. Fetal cells of 15 pregnancies, either chorionic villi or amniotic fluid cells, were used for direct sequence analysis of the respective mutations. Thirteen families were investigated, of which two were affected by N‐acetylglutamate synthase deficiency, four by carbamoylphosphate synthetase 1 deficiency, one by ornithine transcarbamylase deficiency, three by argininosuccinate synthetase deficiency, two by argininosuccinate lyase deficiency, and one by arginase deficiency.ResultsMolecular genetics allowed the determination of the fetal status in all cases. Besides 14 known mutations, we detected the novel mutation c.544delC of the N‐acetylglutamate synthase gene, the novel missense mutation c.721G>A (E241K) of the argininosuccinate lyase gene, and the novel double mutated allele comprising the known mutation c.703G>A (G235R) and the novel insertion c.712ins[GGACC]2 (254X) of the arginase 1 gene.ConclusionDirect genetic analysis of chorionic villi or amniotic fluid cells is feasible, fast, and specific, and can be regarded as the method of choice for prenatal diagnosis in urea cycle disorders. Copyright © 2004 John Wiley & Sons, Ltd.
Base doping and recombination activity of impurities in crystalline silicon solar cells
Authors: Geerligs L. J. , Macdonald D. 
Published: May 2004

AbstractThe optimisation of base doping for industrial crystalline silicon solar cells is examined with model calculations. Focus is on the relation between base doping and carrier recombination through the important impurities interstitial iron (Fei) and the metastable boron–oxygen (BO) complex. Inp‐type silicon, the optimum base resistivity is strongly dependent on defect concentration. Inn‐type silicon, recombination due to Feiis much lower and nearly independent of resistivity. Feiis likely representative for other transition metal impurities. In many real cells a balance between Feior similar defects, and BO will occur. Copyright © 2004 John Wiley & Sons, Ltd.
Hypertext support for the information needs of software maintainers
Authors: Koskinen Jussi , Salminen Airi , Paakki Jukka 
Published: May 2004

AbstractMaking changes safely to programs requires program comprehension and satisfaction of the information needs of software maintainers. In this paper we provide insights into improving hypertext‐based software maintenance support by analyzing those information needs. There exists a series of four earlier, detailed‐level empirical studies on the information needs of professional C program maintainers. We focus on these studies, synthesize their results and determine sources from which the required information might be attained. An experimental research tool, the HyperSoft system, is used to demonstrate the satisfaction of information needs and the system is analytically evaluated against the needs explored by the empirical studies. HyperSoft is based on our transient hypertext approach for software maintenance support. HyperSoft provides automatically generated hypertextual access structures and software visualizations. The results show that transient hypertext is a well‐suited representational form of the typically required versatile information. The discussion also covers related tools and the main features for providing the information required by maintainers are identified. The results show that the focus areas of these tools vary considerably. Copyright © 2004 John Wiley & Sons, Ltd.
Two important exceptions to the relationship between energy density and fat content: foods with reduced-fat claims and high-fat vegetable-based dishes
Authors: Fontaine Helen A La , Crowe Timothy C , Swinburn Boyd A , Gibbons Carl J 
Published: May 2004

AbstractObjective:To test the hypothesis that many foods with reduced-fat (RF) claims are relatively energy-dense and that high-fat (HF) vegetable-based dishes are relatively energy-dilute.Design:Nutrient data were collected from available foods in Melbourne supermarkets that had an RF claim and a full-fat (FF) equivalent. Nutrient analyses were also conducted on recipes for HF vegetable-based dishes that had more than 30% energy from fat but less than 10% from saturated fat. The dietary intake data (beverages removed) from the 1995 National Nutrition Survey were used for the reference relationships between energy density (ED) and percentage energy as fat and carbohydrate and percentage of water by weight.Statistics:Linear regression modelled relationships of macronutrients and ED. Paired t-tests compared observed and predicted reductions in the ED of RF foods compared with FF equivalents.Results:Both FF and RF foods were more energy-dense than the Australian diet and the HF vegetable-based dishes were less energy-dense. The Australian diet showed significant relationships with ED, which were positive for percentage energy as fat and negative for percentage energy as carbohydrate. There were no such relationships for the products with RF claims or for the HF vegetable-based dishes.Conclusion:While, overall, a reduced-fat diet is relatively energy-dilute and is likely to protect against weight gain, there appear to be two important exceptions. A high intake of products with RF claims could lead to a relatively energy-dense diet and thus promote weight gain. Alternatively, a high intake of vegetable-based foods, even with substantial added fat, could reduce ED and protect against weight gain.
Locomotion in bonobos (Pan paniscus): differences and similarities between bipedal and quadrupedal terrestrial walking, and a comparison with other locomotor modes
Authors: D’Août K. , Vereecke E. , Schoonaert K. , De Clercq D. , Van Elsacker L. , Aerts P. 
Published: May 2004

AbstractOne of the great ongoing debates in palaeo‐anthropology is when, and how, hominids acquired habitual bipedal locomotion. The newly adopted bipedal gait and the ancestral quadrupedal gait are most often considered as very distinct, with each habitual locomotor mode showing corresponding anatomical adaptations. Bonobos (Pan paniscus), along with common chimpanzees (P. troglodytes), are the closest living relatives to humans and their locomotion is valuable for comparison with other primates, and to gain an insight in the acquisition of human bipedalism. Bonobos are habitual quadrupeds, but they also engage in bipedal locomotion, both on terrestrial and in arboreal substrates. In terms of kinematics and dynamics, the contrast between bipedal and quadrupedal walking seems to be more subtle than one might expect. Apart from the trunk being approximately 37° more erect during bipedal locomotion, the leg movements are rather similar. Apart from the heel, plantar pressure distributions show subtle differences between bipedal and quadrupedal locomotion. Regardless, variability is high, and various intermediate forms of locomotion (e.g. tripedal walking) exist both in captivity and in the wild. Moreover, there is overlap between the characteristics of walking and other locomotor modes, as we show with new data of walking on an inclined pole and of vertical squat jumps. We suggest that there is great overlap between the many locomotor modes in bonobos, and that the required polyvalence is reflected in their anatomy. This may hamper the development of one highly specialized gait (i.e. bipedalism), which would constrain performance of the other types of locomotion.
Biomimetic robotics should be based on functional morphology
Authors: Witte Hartmut , Hoffmann Helge , Hackert Rémi , Schilling Cornelius , Fischer Martin S. , Preuschoft Holger 
Published: May 2004

AbstractDue to technological improvements made during the last decade, bipedal robots today present a surprisingly high level of humanoid skill. Autonomy, with respect to the processing of information, is realized to a relatively high degree. What is mainly lacking in robotics, moving from purely anthropomorphic robots to ‘anthropofunctional’ machines, is energetic autonomy. In a previously published analysis, we showed that closer attention to the functional morphology of human walking could give robotic engineers the experiences of an at least 6 Myr beta test period on minimization of power requirements for biped locomotion. From our point of view, there are two main features that facilitate sustained walking in modern humans. The first main feature is the existence of ‘energetically optimal velocities’ provided by the systematic use of various resonance mechanisms: (a) suspended pendula (involving arms as well as legs in the swing phase of the gait cycle) and matching of the pendular length of the upper and lower limbs; (b) inverted pendula (involving the legs in the stance phase), driven by torsional springs around the ankle joints; and (c) torsional springs in the trunk. The second main feature is compensation for undesirable torques induced by the inertial properties of the swinging extremities: (a) mass distribution in the trunk characterized by maximized mass moments of inertia; (b) lever arms of joint forces at the hip and shoulder, which are inversely proportional to their amplitude; and (c) twisting of the trunk, especially torsion. Our qualitative conclusions are three‐fold. (1) Human walking is an interplay between masses, gravity and elasticity, which is modulated by musculature. Rigid body mechanics is insufficient to describe human walking. Thus anthropomorphic robots completely following the rules of rigid body mechanics cannot be functionally humanoid. (2) Humans are vertebrates. Thus, anthropomorphic robots that do not use the trunk for purposes of motion are not truly humanoid. (3) The occurrence of a waist, especially characteristic of humans, implies the existence of rotations between the upper trunk (head, neck, pectoral girdle and thorax) and the lower trunk (pelvic girdle) via an elastic joint (spine, paravertebral and abdominal musculature). A torsional twist around longitudinal axes seems to be the most important.
Application of the dual‐beam FIB/SEM to metals research
Authors: SIVEL V. G. M. , VAN DEN BRAND J. , WANG W. R. , MOHDADI H. , TICHELAAR F. D. , ALKEMADE P. F. A. , ZANDBERGEN H. W. 
Published: May 2004

SummaryThe dual‐beam microscope is a combination of a focused ion beam with an electron beam. The instrument used in this work is also equipped with an energy‐dispersive X‐ray system for local elemental analysis. This powerful tool gives access to specific features inside a material. Two different applications are presented in this paper: (1) cross‐sections and transmission electron microscope specimens cut in order to investigate the interface between an aluminium substrate and its epoxy coating; and (2) a grain boundary in a Cu3Au alloy. In both cases, the dual beam succeeded where other methods failed.
Secondary metabolites and plant/environment interactions: a view through Arabidopsis thaliana tinged glasses
Authors: KLIEBENSTEIN D. J. 
Published: May 2004

ABSTRACT Arabidopsis thaliana is a successful model plant for studying wide‐ranging topics including plant development, genetics and pathogen resistance. In addition, significant research has been conducted in the area of secondary metabolite biochemical genetics. The secondary metabolites in Arabidopsis include glucosinolates, terpenoids, phenylpropanoids, the alkaloid‐like camalexin, and other uncharacterized compounds. The genetic tools developed in studying secondary metabolite biochemistry are now being used to study how secondary metabolites control various biological processes. This includes compounds involved in plant/insect and plant/pathogen interactions, compounds preventing UV‐B damage, and compounds involved in hormone homeostasis. This review will describe what light Arabidopsis is shedding on the biological and ecological importance of specific secondary metabolites.
On the mystery of the golden angle in phyllotaxis
Authors: KING S. , BECK F. , LÜTTGE U. 
Published: May 2004

ABSTRACTPhyllotaxis, the arrangement of leaves around a stem, shows in the vast majority of cases a regularity in the divergence angle of subsequent leaves which divide the whole circle into regular fractions. These are in most cases rational fractions of two Fibonacci numbers in an alternating series, converging towards the irrational limit of the golden section, corresponding to the golden divergence angle of 137.5  . . . degrees. This peculiarity was a long‐standing mystery. Here, it is related to the evolutionary pressure of optimal light capture for maximal photosynthetic activity. A model is established which relates minimal shadowing for the lower leaves to the divergence angle. Numerical results of this model agree well with semi‐empirical data on the dependence of light capture from the divergence angle. The basic shadow function of the model is also related with the demand of minimal shadowing for the angular separation of leaves and obtain, using elementary number theory, as solution the golden section. Further numerical studies show that the rational approach to the golden section (Schimper–Braun series) is related to the leaf width and the number of leaves of the plant.
Reef‐capping laminites in the Upper Silurian carbonate‐ to‐evaporite transition, Michigan Basin, south‐western Ontario
Authors: Coniglio Mario , Frizzell ROB , Pratt Brian R. 
Published: May 2004

AbstractSilurian pinnacle reefs in the subsurface of the south‐western Ontario portion of the Michigan Basin display a variety of laminated carbonates (laminites) within predominantly muddy reef‐capping facies in the upper part of the Guelph Formation and the overlying A‐1 Carbonate of the Salina Group. Laminites, which are limestone, dolomite or partially dolomitized limestones, have a range of morphologies, from simple planar to a variety of wavy and serrated forms. Individual laminae are composed mainly of micrite, microspar or replacive dolomite, and vary internally from isopachous and continuous over the diameter of the core to non‐isopachous and often discontinuous. Clotted and peloidal micrite, sometimes defining small knobs and chambers, is interpreted as being microbial in origin and occurs within all types of laminites. Fibrous cement locally comprises laminite clasts in breccias or coats clasts in breccias, and also occurs as spherulites in the interparticle spaces in breccias. Although similar laminites have been described from elsewhere in the Michigan Basin and interpreted as caliche, travertine and abiotic subtidal stromatolites, the laminites in south‐western Ontario are most realistically regarded as microbial. The causes for the variations in morphology and characteristics of the constituent laminae are uncertain, although fluctuations in local microenvironmental conditions would have been important, set against a backdrop of an increasingly restricted overall setting. Caliche or travertine origins for these laminites are unlikely in general, except perhaps locally at the subaerial exposure surface at the tops of pinnacle reefs.
Formation of decollement upwarps during thrusting
Authors: Dubey Ashok Kumar 
Published: May 2004

AbstractGeometric and kinematic models reveal that rotation of layers during thrusting or development of drag folds produced by movement along listric thrust faults results in the formation of dilation space at the junction of the thrust ramp with the basal decollement. This is accompanied by upwarping of the basement to occupy the available space thereby producing an antiformal structure, which restricts the thrust displacement. The structure is termed a decollement upwarp and examples are cited from the foothill belt of the Himalaya.