bluuebunny/crossref_metadata_2025_split huggingface dataset:
On chromatic‐choosable graphs
Authors: Ohba Kyoji 
Published: August 2002

AbstractA graph is chromatic‐choosable if its choice number coincides with its chromatic number. It is shown in this article that, for any graph G, if we join a sufficiently large complete graph to G, then we obtain a chromatic‐choosable graph. As a consequence, if the chromatic number of a graph G is close enough to the number of vertices in G, then G is chromatic‐choosable. We also propose a conjecture related to this fact. © 2002 Wiley Periodicals, Inc. J Graph Theory 40: 130–135, 2002
Sperm storage in the oviduct of the internal fertilizing frog Ascaphus truei
Authors: Sever David M. , Moriarty Emily C. , Rania Lisa C. , Hamlett William C. 
Published: August 2002

AbstractThis study provides the first descriptions of sperm storage at the tissue and cellular levels in a female frog or toad. Oviducal anatomy was studied by light and electron microscopy in Ascaphus truei from north coastal California. Ascaphus truei is one of the few species of anurans in which fertilization is internal. Unlike other anurans with internal fertilization, however, mating in A. truei consists of a unique combination of amplectic and copulatory mechanisms that we term “copulexus.” Posterior to a short, aglandular infundibular region, the oviduct possesses: 1) a proximal, convoluted ampullary region where intrinsic tubular glands secrete gelatinous envelopes around eggs; 2) a middle ovisac region where fertilization occurs; and 3) a distal oviducal sinus formed by medial junction of the ovisacs. Sperm storage tubules (SSTs) occur in the anterior portions of the ovisacs and consist of simple tubular glands. SSTs and the rest of the oviducal lining stain positively with the periodic acid‐Schiff's procedure for neutral carbohydrates and this reaction is especially intense in reproductively active females. Sperm were found in the SSTs of gravid females as well as some nonvitellogenic females. The sperm are in orderly bundles in the SSTs, and although occasionally sperm nuclei were embedded in the epithelium, no evidence for spermiophagy was found. Oviducal sperm storage in A. truei is homoplastic, with closest structural similarities to squamate reptiles. Oviduct/sperm design constraints appear to limit the options for expression of features associated with oviducal sperm storage. J. Morphol. 248:1–21, 2001. © 2001 Wiley‐Liss, Inc.
Anatomy and histology of the brain and sense organs of the Antarctic eel cod Muraenolepis microps (Gadiformes; Muraenolepididae)
Authors: Eastman Joseph T. , Lannoo Michael J. 
Published: August 2002

AbstractBrain regions, cranial nerves, and sense organs in Muraenolepis microps, an Antarctic gadiform fish, were examined to determine which features could be attributed to a gadiform ancestry and which to habitation of Antarctic waters. We found that the central nervous system and sense organs are well developed, showing neither substantial regression nor hypertrophy. A detailed drawing of the brain and cranial nerves is provided. The rostral position of the olfactory bulbs and telencephalic size and lobation are common for the order. The optic tectum and corpus cerebelli are smaller than in most other gadiforms. The shape of the corpus cerebelli is not distinctive among gadiforms. The lateral line region is moderately well‐developed, but not hypertrophied to the extent seen in deep‐sea gadiforms. As is the case in gadids possessing barbels and elongated pelvic rays, Muraenolepis has well‐developed facial lobes, although these are smaller and more laterally positioned. The vagal lobes are deeply placed in the rhombencephalon and project into the fourth ventricle. The brain of Muraenolepis resembles that of a phyletically derived gadoid, especially a phycid, more than it resembles the brain of a phyletically basal macrourid. Two histological features of the diencephalon of Muraenolepis appear to be unique among gadiforms: a well‐organized thalamic central medial nucleus and subependymal expansions. Muraenolepis has a pure rod retina like many deep‐sea species but lacks the superimposed layers of rod outer segments. The histology of the nonvisual sense organs, especially the olfactory and external taste systems, are well‐developed in Muraenolepis but not hypertrophied. We relate our findings to what is known about neural morphology in other gadiforms and in phyletically distant notothenioids and liparids that are sympatric with Muraenolepis on the Antarctic shelf. The only feature that reflects an Antarctic existence is the diencephalic subependymal expansions, which within notothenioids mirror the habitation of cold waters and have been found in every Antarctic species examined to date. Although the waters of the Antarctic shelf are cold, dark, and deep, brain and sense organ morphology in Muraenolepis are remarkably free of extreme specialization. J. Morphol. 250:34–50, 2001. © 2001 Wiley‐Liss, Inc.
The cephalic sensory organ in veliger larvae of pulmonates (Gastropoda: Mollusca)
Authors: Ruthensteiner Bernhard , Schaefer Kurt 
Published: August 2002

AbstractThe apical area of larvae of four primitive pulmonate species was investigated by means of serial ultrathin and light microscope sections. Cephalic sensory organs (CSOs) were found in the larvae of Onchidium cf. branchiferum (Onchidiidae) and Laemodonta octanfracta (Ellobiidae), while no trace of the organ was present in the larvae of Ovatella myosotis (Ellobiidae) or Williamia radiata (Siphonariidae). TEM investigation revealed very similar CSOs in O. cf. branchiferum and L. octanfracta, with characteristic putative sensory cell types: ampullary cells with an internal ampulla containing densely packed cilia, para‐ampullary cells with external cilia parallel to the surface, and ciliary tuft cells, bearing short ciliary tufts. The epithelium covering the organ has a thick microvillar border with microvilli laterally bearing a pair of electron‐dense accumulations and a glycocalyx with interspersed flat plaque‐like elements. While homologues of all major elements of the CSO can be found in other gastropod taxa, for example caenogastropods and opisthobranchs, the homology of the ampullary cell with similar cells in nongastropods appears unlikely. The CSO of L. octanfracta is associated with an additional structure, an epithelial external protrusion, lying ventral to the CSO. The absence of the organ in W. radiata weakens hypotheses on the organ's function of examining settlement conditions and velar control. J. Morphol. 251:93–102, 2002. © 2002 Wiley‐Liss, Inc.
Postnatal skeletal ontogeny in Callisaurus draconoides and Uta stansburiana (Iguania: Phrynosomatidae)
Authors: Maisano Jessica Anderson 
Published: August 2002

AbstractThe mineralization of the skeleton from hatching to near maximum size in two phrynosomatid lizards, Callisaurus draconoides and Uta stansburiana, is described in detail. Observed patterns in the appearance of epiphyseal secondary centers, ossification centers, apophyseal ossifications, and calcifications, the distribution of sesamoids, and the timing of fusions, are compared and contrasted with observations of other squamates available in the literature. Overall, Callisaurus and Uta exhibit an advanced state of ossification in the hatchling relative to other squamate neonates and share a similar sequence of braincase fusions and appearance of secondary centers. Preliminary observations suggest that patterns of postnatal skeletal development are highly conserved and independent of patterns of prenatal morphogenesis, and thus a potentially rich source of character data for systematic investigations. J. Morphol. 251:114–139, 2002. © 2002 Wiley‐Liss, Inc.
Avian furcula morphology may indicate relationships of flight requirements among birds
Authors: Hui Clifford A. 
Published: August 2002

AbstractThis study examined furcula (wishbone) shape relative to flight requirements. The furculae from 53 museum specimens in eight orders were measured: 1) three‐dimensional shape (SR) as indicated by the ratio of the direct distance between the synostosis interclavicularis and the ligamentous attachment of one of its clavicles to the actual length of the clavicle between those same two points, and 2) curvature within the primary plane (LR) as indicated by the ratio of the length of the clavicle to the sum of the orthogonal distances between the same points using a projected image. Canonical discriminant analysis of these ratios placed the individuals into a) one of four general flight categories and b) one of eight taxonomic orders. The four flight categories were defined as: i) soaring with no flapping, ii) flapping with no soaring, iii) subaqueous (i.e., all wingbeats taking place under water), and iv) partial subaqueous (i.e., wingbeats used for both aerial and submerged flapping). The error rate for placement of the specimens in flight categories was only 26.4%, about half of the error rate for placement in taxonomic orders (51.3%). Subaqueous fliers (penguins, great auks) have furculae that are the most V‐shaped. Partial subaqueous fliers (alcids, storm petrels) have furculae that are more U‐shaped than the subaqueous fliers but more V‐shaped than the aerial flapping fliers. The partial subaqueous fliers have furculae that are also the most anteriorly curved, possibly increasing protraction capability by changing the angle of applied force and increasing attachment area for the origin of the sternobrachialis pectoralis. The increased protraction capability can counteract profile drag, which is greater in water than in air due to the greater density of water. Soaring birds have furculae that are more U‐shaped or circular than those of flapping birds and have the smallest range of variation. These results indicate that the shape of the furcula is functionally related to general differences in flight requirements and may be used to infer relationships of these requirements among birds. J. Morphol. 251:284–293, 2002. © 2002 Wiley‐Liss, Inc.
Comparison of isometric contractile properties in hindlimb extensor muscles of the frogs Rana pipiens and Bufo marinus: Functional correlations with differences in hopping performance
Authors: Chadwell Brad A. , Hartwell Hadley J. , Peters Susan E. 
Published: August 2002

AbstractThe leopard frog (Rana pipiens) is an excellent jumper that can reach high take‐off velocities and accelerations. It is diurnal, using long, explosive jumps to capture prey and escape predators. The marine toad (Bufo marinus) is a cryptic, nocturnal toad, typically using short, slow hops, or sometimes walking, to patrol its feeding area. Typical of frogs with these different locomotor styles, Rana has relatively long hindlimbs and large (by mass) hindlimb extensor muscles compared to Bufo. We studied the isometric contractile properties of their extensor muscles and found differences that correlate with their different hopping performances. At the hip (semimembranosus, SM), knee (peroneus, Per) and ankle (plantaris longus, PL), we found that Rana's muscles tended to produce greater maximum isometric force relative to body mass, although the difference was significant only for PL. This suggests that differences in force capability at the ankle may be more important than at other joints to produce divergent hopping performances. Maximum isometric force scaled with body mass so that the smaller Rana has relatively larger muscles and force differences between species may reflect size differences only. In addition, Rana's muscles exhibited greater passive resistance to elongation, implying more elastic tissue is present, which may amplify force at take‐off due to elastic recoil. Rana's muscles also achieved a higher percentage of maximum force at lower stimulus inputs (frequencies and durations) than in Bufo, perhaps amplifying the differences in force available for limb extension during natural stimulation. Twitch contraction and relaxation times tended to be faster in Rana, although variation was great, so that differences were significant only for Per. Fatigability also tended to be greater in Rana muscles, although, again, values reached significance in only one muscle (PL). Thus, in addition to biomechanical effects, differences in hopping performance may also be determined by diverse physiological properties of the muscles. J. Morphol. 251:309–322, 2002. © 2002 Wiley‐Liss, Inc.
Chondrocranial development in larval Rana sylvatica (Anura: Ranidae): Morphometric analysis of cranial allometry and ontogenetic shape change
Authors: Larson Peter M. 
Published: August 2002

AbstractThis study provides baseline quantitative data on the morphological development of the chondrocranium in a larval anuran. Both linear and geometric morphometric methods are used to quantitatively analyze size‐related shape change in a complete developmental series of larvae of the wood frog, Rana sylvatica. The null hypothesis of isometry was rejected in all geometric morphometric and most linear morphometric analyses. Reduced major axis regressions of 11 linear chondrocranial measurements on size indicate a mixture of allometric and isometric scaling. Measurements in the otic and oral regions tend to scale with negative allometry and those associated with the palatoquadrate and muscular process scale with isometry or positive allometry. Geometric morphometric analyses, based on a set of 11 chondrocranial landmarks, include linear regression of relative warp scores and multivariate regression of partial warp scores and uniform components on log centroid size. Body size explains about one‐quarter to one‐third of the total shape variation found in the sample. Areas of regional shape transformation (e.g., palatoquadrate, otic region, trabecular horns) are identified by thin‐plate spline deformation grids and are concordant with linear morphometric results. Thus, the anuran chondrocranium is not a static structure during premetamorphic stages and allometric patterns generally follow scaling predictions for tetrapod cranial development. Potential implications regarding larval functional morphology, cranial development, and chondrocranial evolution in anurans are discussed. J. Morphol. 252:131–144, 2002. © 2002 Wiley‐Liss, Inc.
Quantification of errors in volume measurements of the caudate nucleus using magnetic resonance imaging
Authors: Gurleyik Kilichan , Haacke E. Mark 
Published: August 2002

AbstractPurposeTo quantify the various sources of error in measuring the volume of the caudate nucleus and to understand these errors would lead to the standardization of the MRI protocol and would make the utility of data from around the world more viable in a global database.Materials and MethodsWe collected data at four different sites all using a Siemens 1.5T Vision MR Scanner. In all cases the same 3D gradient‐echo scans were used on a single volunteer and analyzed by a set of five observers.ResultsThe errors estimated were: system calibration (a random variation of up to 1.2%), partial volume error (a bias of up to 1.5% using isotropic resolution of 1 × 1 × 1 mm3), geometric distortion (a potential bias of 1%), intra‐observer error (a random variation of up to 3%), effects of ringing (area biases of up to 7% when a zoom of 4 was used) and inter‐observer error (with a bias of usually 5– 10% but sometimes as large as 16% among our five observers). Individual mean variations from one system to another differed by less than 5% (except for two observers at one site), consistent with a maximum error of 7% coming from the area bias due to limitations in the images themselves. We also measured the effect of variable resolution on the volume estimates and found that the measured volumes were consistent over a broad range of signal‐to‐noise‐ratios (SNRs).ConclusionGiven the observed dependence of the caudate volumes on SNR and resolution, if isotropic resolution is required because a complicated structure is being imaged, then the lower SNR suffered by collecting 1 × 1 × 1 mm3 data at 1.5T still appears to be sufficient to make accurate volume measurements as long as the contrast‐to‐noise ratio (CNR) is on the order of 4:1. Based on our results, predictions are made as to what the best approach would be to improve the data acquisition scheme to keep individual errors under 2% and biases under 3.5%. We conclude that if users can be trained to identify the structure of interest in the same way, the inter‐observer error could be reduced to that of intra‐observer day‐to‐day error. J. Magn. Reson. Imaging 2002;15:353–363. © 2002 Wiley‐Liss, Inc.
Redox buffering in an electrospray ion source using a copper capillary emitter
Authors: Van Berkel Gary J. , Kertesz Vilmos 
Published: August 2002

AbstractAn electrospray ion source used in electrospray mass spectrometry is a two‐electrode, controlled‐current electrochemical flow cell. Electrochemical reactions at the emitter electrode (oxidation and reduction in positive and negative ion modes respectively) provide the excess charge necessary for the quasi‐continuous production of charged droplets and ultimately gas‐phase ions with this device. We demonstrate here that a copper capillary emitter, in place of the more commonly used stainless‐steel capillary emitter, can be utilized as a redox buffer in positive ion mode. Anodic corrosion of the copper capillary during normal operation liberates copper ions to solution and in so doing maintains the interfacial potential at this electrode near the equilibrium potential for the copper corrosion process [E° = 0.34 V versus standard hydrogen electrode (SHE)]. Fixing the interfacial potential at the emitter electrode provides control over the electrochemical reactions that take place at this electrode. It is shown that the oxidation of N‐phenyl‐1,4‐phenylenediamine to N‐phenyl‐1,4‐phenylenediimine (Ep/2 = 0.48 V versus SHE) can be completely avoided using the copper emitter, whereas this analyte is completely oxidized with a stainless‐steel capillary emitter under the same conditions. Moreover, using N‐phenyl‐1,4‐phenylenediimine, we demonstrate that reduction reactions can occur at the copper emitter electrode in positive ion mode. Emitter corrosion, in addition to redox buffering, provides a convenient means to introduce metal ions into solution for analytical use in electrospray mass spectrometry. Published in 2001 by John Wiley & Sons, Ltd.
Guest‐to‐host proton transfer in melatonin–β‐cyclodextrin inclusion complex by ionspray, fast atom bombardment and tandem mass spectrometry
Authors: Bongiorno David , Ceraulo Leopoldo , Mele Andrea , Panzeri Walter , Selva Antonio , Liveri Vincenzo Turco 
Published: August 2002

AbstractIonspray (IS) and fast atom bombardment (FAB) positive ionization mass spectrometry (MS) of 1 : 1 β‐cyclodextrin (β‐CD)–melatonin (MLT) host–guest complex allowed the detection of gaseous protonated 1 : 1 β‐CD–MLT. Tandem MS collision‐induced dissociation (CID) of such protonated 1 : 1 β‐CD–MLT species showed the proton (charge) to be retained to a significant extent by the host and by its cage fragmentation products, in spite of the higher proton affinity of MLT with respect to that of β‐CD. This requires an endothermic guest‐to‐host proton transfer to occur within the gaseous association. Collisional activation could be accounted for by the promotion of such an endothermic process; however, the proton affinity decrease of the guest determined by the loss of the elements of acetamide, which is a dominant MS dissociation reaction of pure protonated MLT, could also provide a rationale for such an endothermic guest‐to‐host proton transfer. This proposal parallels the reaction scheme we had previously formulated for the analogous MS and tandem MS behaviour of 1 : 1 β‐CD–5‐methoxytryptamine inclusion complex with the protonated 5‐methoxytryptamine guest undergoing deamination. Copyright © 2001 John Wiley & Sons, Ltd.
Characterization of multimetallic grid‐type complexes by electrospray mass spectrometry
Authors: Nierengarten Hélène , Leize Emmanuelle , Breuning Esther , Garcia Ana , Romero‐Salguero Francisco , Rojo Javier , Lehn Jean‐Marie , Van Dorsselaer Alain 
Published: August 2002

AbstractThe self‐assembly of the terdentate ligands 1a–h, based on terpyridine‐like binding sites, with octahedrally coordinated metal ions, such as FeII, CoII, CuII, ZnII, CdII, HgII and PbII, leads to the formation of the supramolecular grid‐type complexes 2a–c(MII), 3d–g(MII) and 4h(MII). The structures and compositions of these coordination complexes in solution were deduced from electrospray mass spectrometry (ESMS) measurements. The results agree with the data available from x‐ray radiocrystallography in the solid state and/or NMR spectroscopy in solution. ESMS may be applied in cases where other methods are difficult to use or inconclusive. This study stresses the power of ESMS in supramolecular chemistry. Copyright © 2001 John Wiley & Sons, Ltd.
Parvovirus B19 nonstructural (NS1) protein as a transactivator of interleukin‐6 synthesis: Common pathway in inflammatory sequelae of human parvovirus infections?
Authors: Mitchell Leslie Ann 
Published: August 2002

AbstractThis review focuses on the role that human parvovirus B19 nonstructural (NS1) protein as a transactivator of the proinflammatory cytokine, interleukin‐6 (IL‐6), might play in triggering the multiparametric inflammatory outcomes of B19 infection. Parvovirus B19 is a ubiquitous virus, and it is often expressed during conditions of immunodepression including that induced by long‐term chemotherapy, viral infection (HIV, HTLV‐1), or genetic immunodeficiency disorders. Through NS1 expression, B19 may contribute to the immune dysregulation associated with these disorders, or serve as a cofactor in enhancing retroviral replication. Hence, NS1 transactivation of proinflammatory cytokine promoters such as IL‐6 may be pivotal in triggering the various inflammatory and autoimmune disorders that have been linked to parvovirus B19 infections. J. Med. Virol. 67:267–274, 2002. © 2002 Wiley‐Liss, Inc.
Cross code comparison between NEC 4 and transmission line matrix (TLM) methods for whole ship modelling
Authors: Kazik John J. 
Published: August 2002

AbstractThis paper describes the application of transmission line matrix methods (TLM) as a possible alternative technique to NEC for the modelling of the electromagnetic environment found on board typical ship topsides. It presents the results of an initial feasibility study demonstrating that TLM can produce similar results to an equivalent NEC model. It then demonstrates the results of an initial and refined ship model, where TLM required a single day for the same frequency range and output as the equivalent NEC model, requiring more than 15 days.The paper presents initial results comparing antenna impedance and radiation patterns as determined by both methods. The paper also demonstrates the capability of the TLM technique to assess complex objects with only the power of a typical commercially available desktop PC. © Crown copyright 2001. Reproduced with the permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd.