bluuebunny/crossref_metadata_2025_split huggingface dataset:
Embryonic integument and “molts” in manduca sexta (insecta, lepidoptera)
Authors: Ziese Stefanie , Dorn August 
Published: December 2002

AbstractIn Manduca sexta the germ band is formed 12 h post‐oviposition (p.o.) (=10% development completed) and is located above the yolk at the egg surface. The cells show a polar organization. They are engaged in the uptake and degradation of yolk globules, pinched off from the yolk cells. This process can be observed in the integumental cells during the first growth phase of the embryo that lasts until “katatrepsis,” an embryonic movement that takes place at 40% development completed. At 37% development completed, the ectoderm deposits a thin membrane at its apical surface, the first embryonic membrane, which detaches immediately before katatrepsis. The second period of embryonic growth—from katatrepsis to 84 h p.o. (70% development completed)—starts with the deposition of a second embryonic membrane that is somewhat thicker than the first one and shows a trilaminar, cuticulin‐like structure. Whereas the apical cell surface is largely smooth during the deposition of the first embryonic membrane, it forms microvilli during deposition of the second one. At the same time, uptake of formed yolk material ceases and the epidermal cells now contain clusters of mitochondria below the apical surface. Rough endoplasmic reticulum (RER) increases in the perinuclear region. The second embryonic membrane detaches about 63 h p.o. At 69 h p.o., a new generation of microvilli forms and islands of a typical cuticulin layer indicate the onset of the deposition of the larval cuticle. The third growth phase is characterized by a steady increase in the embryo length, the deposition of the larval procuticle, and by cuticular tanning at about 100 h p.o. Beginning at that stage, electron‐lucent vesicles aggregate below the epidermal surface and are apparently released below the larval cuticle. Manduca sexta is the first holometabolous insect in which the deposition of embryonic membranes and cuticles has been examined by electron microscopy. In correspondence with hemimetabolous insects, the embryo of M. sexta secretes three covers at approximately the same developmental stage. A marked difference: the second embryonic cover, which in Hemimetabola clearly exhibits a cuticular organization, has instead a membranous, cuticulin‐like structure. We see the difference as the result of an evolutionary reductional process promoted by the redundancy of embryonic covers in the egg shell. Embryonic “molts” also occur in noninsect arthropods; their phylogenetical aspects are discussed. J. Morphol. 255:146–161, 2003. © 2002 Wiley‐Liss, Inc.
Kinematic model of tyrannosaurid (dinosauria: theropoda) arctometatarsus function
Authors: Snively Eric , Russell Anthony P. 
Published: December 2002

AbstractWe present a hypothesis of tyrannosaurid foot function termed the “tensile keystone model,” in which the triangular central metatarsal and elastic ligaments dynamically strengthened the foot. The tyrannosaurid arctometatarsus, in which the central metatarsal is proximally constricted, displays osteological correlates of distal intermetatarsal ligaments. The distal wedge‐like imbrication of tyrannosaurid metatarsals indicates that rebounding ligaments drew the outer elements towards the middle digit early in the stance phase, unifying the arctometatarsus under high loadings. This suggests increased stability and resistance to dissociation and implies, but does not demonstrate, greater agility than in large theropods without an arctometatarsus. J. Morphol. 255:215–227, 2003. © 2002 Wiley‐Liss, Inc.
Development of the basement membrane and formation of collagen fibrils below the placodes in the head of anuran larvae
Authors: Osawa Tokuji , Feng Xin‐Yan , Yamamoto Masanori , Nozaka Momoki , Nozaka Yohichiro 
Published: December 2002

AbstractThe development of the basement membrane and collagen fibrils below placodes, including the corneal region of the ectoderm, lens epithelium, nasal plate, and auditory vesicle in anuran larvae was observed by transmission electron microscopy and compared with that in nonplacodal regions such as the epidermis, neural tube, and optic vesicle. In the corneal region the lamina densa becomes thick concomitantly with the development of the connecting apparatuses such as hemidesmosomes and anchoring fibrils. The collagen fibrils increase in number and form a multilayered structure, showing similar morphology to the connective tissues below the epidermis. These two areas, i.e., the corneal region and epidermis, possess much collagenous connective tissue below them. On the other hand, the neural tube and ophthalmic vesicle that originated from the neural tube each have a thin lamina densa and a small number of underlying collagen fibrils. The lamina densa does not thicken and the number of collagen fibrils do not significantly increase during development. These two areas possess little extracellular matrix. The nasal plate and auditory vesicle show intermediate characteristics between the epidermis‐type and the neural tube‐type areas. In these areas, the lamina densa becomes thick and hemidesmosomes and anchoring fibrils develop. The number of collagen fibrils increases during development, but does not show an orderly arrangement; rather, they are randomly distributed. It is thought that the difference in the arrangement of collagen fibrils in different tissues is due to differences in the extracellular matrix around the collagen fibrils. Placodal epithelia have the same origin as epidermis, but during development their morphological characteristics differ and they are not associated with the pattern of extracellular matrix with characteristics of epidermal and corneal multilayered collagen fibril areas. J. Morphol. 255:244–252, 2003. © 2002 Wiley‐Liss, Inc.
Microampullary organs of a freshwater eel‐tailed catfish, plotosus (tandanus) tandanus
Authors: Whitehead Darryl L. , Tibbetts Ian R. , Daddow Lina Y.M. 
Published: December 2002

AbstractWhole body studies of Plotosus tandanus revealed that ampullary pores occur over the entire body of the fish, but are in higher concentrations in the head region. These pores give rise to a short canal (50–60 μm) produced by columnar epithelial cells bound together by tight junctions and desmosomes. At the junction of the canal and the ampulla, cuboidal epithelial cells make up the wall. The ampulla consists of layers of collagen fibers that surround flattened epithelial cells in the lateral regions and give rise to supportive cells that encase a small number of receptor cells (10–15). The ampullary wall comprises several types of cells that are adjoined via tight junctions and desmosomes between cell types. The ovoid receptor cells possess microvilli along the luminar apical area. Beneath this area, the cells are rich in mitochondria and rough endoplasmic reticulum. An unmyelinated neuron adjoins with each receptor cell opposite multiple presynaptic bodies. This form of microampulla has not been previously described within the Family Plotosidae. J. Morphol. 255:253–260, 2003. © 2002 Wiley‐Liss, Inc.
State‐resolved collisional energy transfer of OH, NH and H2CO by two‐color resonant four‐wave mixing spectroscopy
Authors: Radi P. P. , Kouzov A. P. 
Published: December 2002

AbstractExtra resonances observed in two‐color resonant four‐wave mixing (TC‐RFWM) spectra, which originate from collision‐induced energy transfer processes, were investigated experimentally and theoretically. It is shown that the resonances yield information on state‐to‐state rotational energy transfer (RET) occurring in the ground and excited states of OH and NH. The measurements were performed in situ in an equilibrium medium of high temperature and high density. The results shed more light on the propensity rules for the change in the fine‐structure label and rotational quantum number of NH. A comparison with a recent investigation of NH RET on the ground‐state potential yielded good agreement. A theoretical frequency‐domain picture was developed with the help of exact (off‐diagonal) relaxation matrices and general four‐level schemes. The theoretical results were compared with measured relative TC‐RFWM intensities of the OH radical obtained in a flame. Furthermore, the investigation on diatomic radicals was extended to the polyatomic formaldehyde (H2CO) molecule. Initial cell experiments were performed at low pressure by using CO2 as a quencher. The observation of collision‐induced resonances in the ground state of H2CO indicate the potential of the method for the investigation of RET processes occurring in polyatomic molecules in equilibrium media. Copyright © 2002 John Wiley & Sons, Ltd.
Degenerate four‐wave mixing thermometry on the 2B1(k″ = 0)–2A1(k′ = 1) Douglas–Huber band of NO2
Authors: De Dominicis L. , Fantoni R. 
Published: December 2002

AbstractWe report on the application of degenerate four‐wave mixing (DFWM) spectroscopy to the study of the temperature dependence of the 2B1(k″ = 0)–2A1(k′ = 1) Douglas–Huber band of NO2 up to 473 K. Measurements were performed in a static optical cell filled with pure samples at a pressure of 0.1 mbar. The possibility of selecting well‐isolated spectral features for thermometric application using the Boltzmann plot method (BPM) was investigated. Experimental data indicated that at T ≥ 393 K the use of BPM method has to be restricted to transitions with rotational quantum numbers N ≤ 15. Temperature predictions based on the BPM were compared with concurrent measurements performed with a thermocouple. Copyright © 2002 John Wiley & Sons, Ltd.
Bragg resonance‐enhanced coherent anti‐Stokes Raman scattering in a planar photonic band‐gap waveguide
Authors: Konorov S. O. , Akimov D. A. , Naumov A. N. , Fedotov A. B. , Miles R. B. , Haus J. W. , Zheltikov A. M. 
Published: December 2002

AbstractA planar periodically corrugated waveguide, consisting of a grating and a mirror and integrating a hollow waveguide and a photonic band‐gap structure into a single compact optical element, is shown to enhance coherent anti‐Stokes Raman scattering (CARS) in molecular nitrogen. Cross‐correlation measurements, intended to visualize group‐delay effects in the photonic band‐gap waveguide and performed with picosecond Nd : YAG laser pulses, and also the measured dependence of CARS efficiency on the thickness of the waveguide layer, indicate that CARS enhancement under these conditions is at least partially due to the decrease in the group velocity of pump pulses around the photonic band gap. Copyright © 2002 John Wiley & Sons, Ltd.
Microstructure‐fiber sources of mode‐separable supercontinuum emission for wave‐mixing spectroscopy
Authors: Fedotov A. B. , Zhou Ping , Tarasevitch A. P. , Dukel'skii K. V. , Kondrat'ev Yu. N. , Shevandin V. S. , Smirnov V. B. , von der Linde D. , Zheltikov A. M. 
Published: December 2002

AbstractMicrostructure fibers are shown to provide a high efficiency of generation of mode‐separable and frequency‐convertible supercontinuum of a high spectral and spatial quality, offering much promise as sources of broadband radiation for wave‐mixing spectroscopy and time‐resolved pump–probe measurements, and also for seeding optical parametric amplifiers. The long‐wavelength and visible parts of supercontinuum emission generated by 40 fs pulses of 800 nm Ti : sapphire laser radiation in fused‐silica microstructure fibers are shown to be spatially separated in microstructure‐fiber modes. With an appropriate spectral filtering, bell‐shaped modes of the long‐wavelength section (∼720–900 nm) of the supercontinuum generated in a microstructure fiber with a small core diameter can be separated from either doughnut‐like or bipartite modes of the visible part (∼400–600 nm) of this supercontinuum. This effect can be employed for the spectral slicing of single modes of supercontinuum emission from microstructure fibers. Frequency convertibility of spectrally sliced supercontinuum is demonstrated by experiments on sum‐frequency generation in a non‐linear crystal. Copyright © 2002 John Wiley & Sons, Ltd.
Laser coherent control of molecular chiral states via entanglement of the rotational and torsional degrees of freedom
Authors: Bychkov Stanislav S. , Grishanin Boris A. , Zadkov Victor N. , Takahashi Hiroaki 
Published: December 2002

AbstractA new mechanism for controlling chiral states in simple chiral molecules with internal rotation, which employs the coherent quantum entanglement of the rotational–torsional states of the molecules, is proposed. It requires no preliminary spatial alignment of the molecules in a solution. A novel scenario for the preferential laser synthesis of enantiomers from a racemic solution of chiral molecules employing this new mechanism of inducing chirality is proposed and analyzed in detail and experimental scheme realizing this scenario is discussed. It is suggested that a non‐linear optical activity coherent anti‐Stokes Raman scattering (NOA‐CARS) spectroscopic technique is used for both inducing the gyration wave in the medium (vapor) of chiral molecules and detecting this photoinduced gyration wave in the medium by registering the NOA‐CARS signal. All numerical estimates are made for the hydrogen peroxide and deuterated hydrogen peroxide chiral molecules. Copyright © 2002 John Wiley & Sons, Ltd.
CARS investigation of hydrogen Q‐branch linewidths at high temperatures in a high‐pressure H2–O2 pulsed burner
Authors: Clauss W. , Klimenko D. N. , Oschwald M. , Vereschagin K. A. , Smirnov V. V. , Stelmakh O. M. , Fabelinsky V. I. 
Published: December 2002

AbstractHydrogen Q‐branch rotational component line‐broadening coefficients for hydrogen–water collisions were determined at 2700 K. For linewidth measurements CARS spectroscopy with a Fabry–Perot interferometer and a multichannel detector was applied. In order to perform these experiments, a high‐pressure pulsed hydrogen–oxygen burner with variable and controlled pressure was designed. Temperature measurements inside the burner were performed simultaneously with the help of broadband CARS spectroscopy. Copyright © 2002 John Wiley & Sons, Ltd.
Dicke effect in hydrogen S0(0) rotational transition observed by time‐domain CARS
Authors: Arakcheev V. , Jakovlev D. , Mochalov S. , Morozov V. , Olenin A. , Tunkin V. 
Published: December 2002

AbstractThe Dicke effect in the hydrogen S0(0) rotational transition (354 cm−1) in forward scattering geometry was observed using time‐domain CARS. Dicke effect measurements were performed at room temperature and with cooling by liquid nitrogen. The observed slowest decays of the impulse responses correspond to the narrowest S0(0) transition spectral linewidths of 1.1 × 10−3 cm−1 (296 K) and 0.45 × 10−3 cm−1 (85 K). At 85 K, the impulse responses coincided satisfactorily with the theoretical values calculated for statistically independent collisional perturbations of translational and rotational motions. At 296 K, some discrepancy between experiment and theory was observed. Copyright © 2002 John Wiley & Sons, Ltd.
Rocket nozzle cold‐gas flow velocity measurements using laser‐induced gratings
Authors: Hemmerling B. , Neracher M. , Kozlov D. , Kwan W. , Stark R. , Klimenko D. , Clauss W. , Oschwald M. 
Published: December 2002

AbstractThe heterodyne detection laser‐induced electrostrictive gratings technique was employed for characterization of a flow velocities field in the plume of a rocket nozzle. The intention of the work was to validate CFD calculations, that predict the appearance of a recirculation zone inside the flow at a certain ratio of nozzle and ambient pressures. This zone co‐exists with the side loads to the nozzle wall that were observed experimentally as transient forces during the start‐up or the shut‐down of the thrust chamber. Measurements were performed in cold‐gas flows from a subscale thrust‐optimized, parabolic nozzle. Nitrogen at stagnation pressures up to 40 bar was supplied to the nozzle. The experimental results clearly proved the existence of a recirculation zone in the flow field, in a reasonable agreement with the predictions of CFD calculations. Copyright © 2002 John Wiley & Sons, Ltd.
Pressure‐dependent N2 Q‐branch fs‐CARS measurements
Authors: Knopp G. , Beaud P. , Radi P. , Tulej M. , Bougie B. , Cannavo D. , Gerber T. 
Published: December 2002

AbstractWe demonstrate the feasibility of the time‐delayed femtosecond CARS (fs‐CARS) technique in a dense gas environment. The experiments were performed on N2 molecules between 0.2 and 5 bar pressure. The method provides several advantages compared with its wavenumber‐resolved counterpart, e.g. the possible separation of the non‐resonant contributions to the signal, and is more suitable when the isolated lines approximations collapse and complex line mixing and energy transfer models have to be implemented in the signal description. The experimental results are in good agreement with theoretical considerations based on collision‐induced rotational energy transfer (RET) models such as the common energy‐corrected sudden approximation (ECS). Moreover, it is shown that the structure of the time‐delayed signals is very sensitive to the applied pressures. Therefore, fs‐CARS is an ideal supplementary tool for investigations of collision‐induced spectroscopic effects, which are decisive for temperature and concentration determination in combustion processes. Copyright © 2002 John Wiley & Sons, Ltd.
Microplane constitutive model for porous isotropic rocks
Authors: Bažant Zdeněk P. , Zi Goangseup 
Published: December 2002

AbstractThe paper deals with constitutive modelling of contiguous rock located between rock joints. A fully explicit kinematically constrained microplane‐type constitutive model for hardening and softening non‐linear triaxial behaviour of isotropic porous rock is developed. The microplane framework, in which the constitutive relation is expressed in terms of stress and strain vectors rather than tensors, makes it possible to model various microstructural physical mechanisms associated with oriented internal surfaces, such as cracking, slip, friction and splitting of a particular orientation. Formulation of the constitutive relation is facilitated by the fact that it is decoupled from the tensorial invariance restrictions, which are satisfied automatically. In its basic features, the present model is similar to the recently developed microplane model M4 for concrete, but there are significant improvements and modifications. They include a realistic simulation of (1) the effects of pore collapse on the volume changes during triaxial loading and on the reduction of frictional strength, (2) recovery of frictional strength during shearing, and (3) the shear‐enhanced compaction in triaxial tests, manifested by a deviation from the hydrostatic stress–strain curve. The model is calibrated by optimal fitting of extensive triaxial test data for Salem limestone, and good fits are demonstrated. Although these data do not cover the entire range of behaviour, credence in broad capabilities of the model is lend by its similarity to model M4 for concrete—an artificial rock. The model is intended for large explicit finite‐element programs. Copyright © 2002 John Wiley & Sons, Ltd.
The proliferation marker pKi‐67 organizes the nucleolus during the cell cycle depending on Ran and cyclin B
Authors: Schmidt Mirko HH , Broll Rainer , Bruch Hans‐Peter , Bögler Oliver , Duchrow Michael 
Published: December 2002

AbstractThe proliferation marker pKi‐67 (‘Ki‐67 antigen’) is commonly used in clinical and research pathology to detect proliferating cells, as it is only expressed during cell‐cycle progression. Despite the fact that this antigen has been known for nearly two decades, there is still no adequate understanding of its function. This study has therefore identified proteins that interact with pKi‐67, using a yeast two‐hybrid system. A mammalian two‐hybrid system and immunoprecipitation studies were used to verify these interactions. Among other cell‐cycle regulatory proteins, two binding partners associated with the small GTPase Ran were identified. In addition, DNA‐structural and nucleolus‐associated proteins binding to pKi‐67 were found. Moreover, it was demonstrated that the N‐terminal domain of pKi‐67 is capable of self‐binding to its own repeat region encoded by exon 13. Since RanBP, a protein involved in the transport of macromolecules over the nuclear lamina, was found to be a binding partner, a possible effect of pKi‐67 on the localization of cell‐cycle regulatory proteins was proposed. To test this hypothesis, a tetracycline‐responsive gene expression system was used to induce the pKi‐67 fragments previously used for the two‐hybrid screens in HeLa cells. Subsequent immunostaining revealed the translocation of cyclin B1 from cytoplasm to nucleoli in response to this expression. It is suggested that pKi‐67 is a Ran‐associated protein with a role in the disintegration and reformation of the nucleolus and thereby in entry into and exit from the M‐phase. Copyright © 2002 John Wiley & Sons, Ltd.
Chemokine expression in IBD. Mucosal chemokine expression is unselectively increased in both ulcerative colitis and Crohn's disease
Authors: Banks Charmian , Bateman Adrian , Payne Richard , Johnson Penny , Sheron Nick 
Published: December 2002

AbstractMucosal changes in inflammatory bowel disease (IBD) are characterized by ulcerative lesions accompanied by prominent cellular infiltrates in the bowel wall. Chemokines are chemotactic cytokines that are able to promote leukocyte migration to areas of inflammation and are also able to initiate cell activation events. They have recently been implicated in the pathophysiology of many disease states. The aim of this study was to detail the degree and distribution of specific chemokines, interleukin (IL)‐8, monocyte chemoattractant protein (MCP)‐1, ‐2, and ‐3, and macrophage inflammatory protein (MIP)‐1α and ‐1β, in IBD mucosa. Thirty‐nine patients were included, ten controls, 20 ulcerative colitis (UC), and nine Crohn's disease (CD), with a range of disease activity. Colonic mucosal biopsies were collected from UC, CD, and control patients and embedded in glycol methacrylate. Two‐micrometre‐thick sections were cut and stained using immunohistochemistry for chemokine protein expression. Sections were analysed using a light microscope. Expression of all types of chemokine protein was detected in colonic mucosa from both control and IBD patients. Patterns of staining between IBD patients and controls differed significantly, but CD and UC patients demonstrated similar patterns of staining. Individual chemokine expression was found to be significantly up‐regulated in IBD when patients were compared with the non‐diseased group in all areas of the mucosal sections. Up‐regulated chemokine expression correlated with increasing activity of the disease. It is concluded that human colonic chemokine expression is non‐selectively up‐regulated in IBD. The results supported the hypothesis that the degree of local inflammation and tissue damage in UC and CD is dependent on local expression of specific chemokines within IBD tissues. Copyright © 2002 John Wiley & Sons, Ltd.