bluuebunny/crossref_metadata_2025 huggingface dataset:
Semibatch styrene suspension polymerization processes
Authors: Lenzi Marcelo Kaminski , Silva Fabricio Machado , Lima Enrique Luis , Pinto José Carlos
Published: June 2003

Emulsion and suspension polymerization processes have widely been studied for more than 40 years. Although both polymerization processes are performed in heterogeneous media, each one presents its own typical characteristics, such as the particle size distribution, molecular weight distribution, polymer particle nucleation rate, and polymerization rate. In this study, semibatch styrene suspension polymerizations were carried out with feed compositions typical of emulsion processes. The initial reactor charge resembled the recipe of standard styrene suspension polymerizations, and the emulsion polymerization constituents were added during the batch. The influence of the moment at which the emulsion feed was started on the course of the polymerization and the effects of the feed on the polymer properties were analyzed. The polymer particle morphology and the average molecular weights changed very significantly with the emulsion feed time, and the changes could lead to the production of broad molecular weight distributions. Core–shell polymer particles could also be obtained, with the core being formed of polymer particles originating from the suspension polymerization process and the shell being formed of polymer particles originating from the emulsion polymerization. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3021–3038, 2003
Tautomerism of 4‐Hydroxy‐2,5‐dimethyl‐3(2H)‐furanone: Evidence for its enantioselective biosynthesis
Authors: Raab Thomas , Hauck Tobias , Knecht Anja , Schmitt Ulrich , Holzgrabe Ulrike , Schwab Wilfried
Published: June 2003

Chiral natural flavor compounds exhibit characteristic enantiomeric excesses due to stereoselective, enzymatically catalyzed reactions during biogenesis. Although the enzymatic formation of the strawberry key flavor compound 4‐hydroxy‐2,5‐dimethyl‐3(2H)‐furanone (HDMF; Furaneol®) is anticipated, the naturally occurring compound is racemic. As racemization due to keto‐enol‐tautomerism of HDMF could account for this observation, HDMF was investigated by 1H‐NMR spectroscopy tracing the exchange of the proton bound to the furanone‐ring at C2 with deuteron from the medium (D2O). In addition, the racemization rate of HDMF was directly determined by cyclodextrin‐modified capillary electrophoresis of enantiomerically enriched HDMF stored at different pH values. Tautomerism and the racemization rate of HDMF was lowest at pH values between 4 and 5. However, tautomerism and thus racemization was catalyzed under stronger acidic conditions (pH 2) and especially at pH values greater than 7, the value published for plant cell cytosol. Approximately 50% of the protons at C2 were exchanged with deuteron within 1 h at pH 7.2. Therefore, in order to demonstrate the enzymatic formation of HDMF, incubation experiments with Zygosaccharomyces rouxii as well as strawberry protein extract were carried out under slightly acidic conditions (pH 5), the most suitable pH value for studies on the enantiomeric ratio of HDMF. In both experiments the formation of enantiomerically enriched HDMF could be demonstrated for the first time, whereas incubation experiments under neutral conditions resulted in the detection of racemic HDMF. Chirality 15:573–578, 2003. © 2003 Wiley‐Liss, Inc.
Atropisomeric amides: Achiral ligands with chiral conformations
Authors: Honda Ayako , Waltz Karen M. , Carroll Patrick J. , Walsh Patrick J.
Published: June 2003

A new class of achiral ligands with atropisomeric conformations has been coordinated to titanium(IV). The ligands are ortho‐hydroxy benzamide derivatives which are deprotonated on reaction with titanium tetraisopropoxide to furnish Ti(L)2(O‐iPr)2 complexes (L=ortho‐phenoxy benzamide). In these octahedral titanium compounds, the ortho‐phenoxy benzamide ligands chelate to titanium, bonding through the phenoxide oxygen and the amide carbonyl oxygen. The benzamide ligands adopt atropisomeric conformations with an angle between the aryl and amide groups of approximately 35°. The ligand precursor, ligand, and titanium complexes have been characterized by X‐ray crystallography. Only one diastereomer of each titanium complex was observed in the solid state structures. Chirality 15:615–621, 2003. © 2003 Wiley‐Liss, Inc.
Hierarchical regression with misaligned spatial data: relating ambient ozone and pediatric asthma ER visits in Atlanta
Authors: Zhu Li , Carlin Bradley P. , Gelfand Alan E.
Published: June 2003

Recent work by the authors enabled a hierarchical modeling solution to the general change of support problem (COSP), where they seek to make inferences about the values of a variable at either points or regions different from those at which it has been observed. The approach presumes an underlying continuous stationary spatial process X (s) for locations s ∈ D, a region of interest. It is straightforwardly extended to the spatio‐temporal setting by assuming a space–time separable covariance function for the X (s, t) process, t ∈ T and again s ∈ D. In this article they take up the associated misaligned regression problem, where, for example, the explanatory variable is envisioned from the X (s, t) process, while the response is available only as areal summaries over a particular grid at particular times. They illustrate using a dataset relating several air quality indicators (ozone, particulate matter, nitrogen oxides, etc.) and a range of sociodemographic variables (age, gender, race, and a socioeconomic status surrogate) to the response, pediatric emergency room (ER) visit counts for asthma in Atlanta, Georgia. Here the air quality data is collected at fixed monitoring stations (point locations) while the sociodemographic covariates and response variable is collected by zip code (areal summaries). In fact, the air quality data are available as daily averages at each monitoring station, and the response is available as daily counts of visits in each zip code. As is now common in hierarchical Bayesian spatial applications, computing is implemented via a carefully tailored Metropolis–Hastings algorithm, with map summaries created using a geographic information system (GIS). Like many recent investigations of the ozone–asthma link, our results suggest a small positive association, though our data can permit this conclusion only for those children living in the city of Atlanta who use the ER to manage their asthma. Copyright © 2003 John Wiley & Sons, Ltd.
Characterization of urea transport in Bufo arenarum oocytes
Authors: Silberstein Claudia , Zotta Elsa , Ripoche Pierre , Ibarra Cristina
Published: June 2003

Xenopus laevis oocytes have been extensively used for expression cloning, structure/function relationships, and regulation analysis of transporter proteins. Urea transporters have been expressed in Xenopus oocytes and their properties have been described. In order to establish an alternative system in which urea transporters could be efficiently expressed and studied, we determined the urea transport properties of ovarian oocytes from Bufo arenarum, a toad species common in Argentina. Bufo oocytes presented a high urea permeability of 22.3 × 10−6 cm/s, which was significantly inhibited by the incubation with phloretin. The urea uptake in these oocytes was also inhibited by mercurial reagents, and high‐affinity urea analogues. The urea uptake was not sodium dependent. The activation energy was 3.2 Kcal/mol, suggesting that urea movement across membrane oocytes may be through a facilitated urea transporter. In contrast, Bufo oocytes showed a low permeability for mannitol and glycerol. From these results, we propose that one or several specific urea transporters are present in ovarian oocytes from Bufo arenarum. Therefore, these oocytes cannot be used in expression studies of foreign urea transporters. The importance of Bufo urea transporter is not known but could be implicated in osmotic regulation during the laying of eggs in water. J. Exp. Zool. 298A:10–15, 2003. © 2003 Wiley‐Liss, Inc.
Skin epithelial transport and structural relationships in naturally metamorphosing Pelobates syriacus
Authors: Katz Uri , Rozman Alexander , Gabbay Shosh
Published: June 2003

The onset of active Na+ transport and activated Cl− conductance (GCl) across the skin epithelium of Pelobates syriacus was investigated during natural ontogenetic development. Structural features, including band three and Peanut lectin bindings were tested in parallel and structure‐function relationships were attempted. The 22 specimens studied were divided into two tadpole, three juvenile, and two adult stages, corresponding to the Taylor‐Kollros standard table, in accordance with external morphology of their developmental stage. Onset of transepithelial electrical potential and drop in conductance occurred abruptly, coinciding with metamorphosis climax of tadpoles into juveniles at about stage XXI of development. Amiloride‐sensitive Na+ transport occurred a little later at stage XXIII, followed by the appearance of activated Cl− conductance, GCl. Parallel structural examination showed that skin MR cells occurred upon metamorphosis, as the tadpole integument transformed into the adult epithelium and could be associated with the occurrence of activated GCl. It was not related temporally with the appearance of band three protein in MR cells. Our findings support the association of GCl with MR cells, whereas band three may only be a corollary of GCl and not necessarily essential for its manifestation. J. Exp. Zool. 298A:1–9, 2003. © 2003 Wiley‐Liss, Inc.
Steroidal modulation of In Vitro gonadotropin secretion in prepubertal and adult male siberian hamsters
Authors: Pak Toni R. , Lynch G. Robert , Tsai Pei‐San
Published: June 2003

The effects of exogenous gonadal steroids, testosterone (T), and 17β‐estradiol (E2) upon the hypothalamo‐pituitary‐gonadal axis were reported to be different between prepubertal and adult Siberian hamsters. Utilizing an in vitro static culture system, we investigated if age‐related differences in steroid responsiveness occurs at the pituitary. Prepubertal (20 days old) or adult (140 days old) male Siberian hamsters were implanted with 1 mm silastic capsules containing undiluted T, E2 or cholesterol (Ch, control). After 15 days, pituitaries were removed, incubated in vitro, and subjected to the following treatments: two baseline measurements, one challenge with 10ng/ml of D‐Lys6‐gonadotropin‐releasing hormone (GnRH), and three post‐challenge washes. Fractions were collected every 30 minutes and measured for follicle‐stimulating hormone (FSH) and luteinizing hormone (LH). T and E2 reduced basal secretion of LH and FSH in juveniles but not adults. In juveniles, E2 increased GnRH‐induced FSH and LH secretion, while T augmented GnRH‐induced FSH secretion but attenuated GnRH‐induced LH secretion. Steroid treatment had no effect on GnRH‐stimulated LH or FSH release in adults. The only effect of steroid hormones upon adult pituitaries was the more rapid return of gonadotropin secretion to baseline levels following a GnRH challenge. These data suggest both basal and GnRH‐induced gonadotropin secretion are more sensitive to steroid treatment in juvenile hamsters than adults. Further, differential steroidal regulation of FSH and LH at the level of the pituitary in juveniles might be a mechanism for the change in sensitivity to the negative effects of steroid hormones that occurs during the pubertal transition. J. Exp. Zool. 298A:53–59, 2003. © 2003 Wiley‐Liss, Inc.
Surgical transplantation of sexually immature ovaries in rainbow trout (Oncorhynchus mykiss)
Authors: Cloud J.G.
Published: June 2003

Transplantation of testes between isogenic rainbow trout males has been recently demonstrated. The objective of the present investigation was to determine if ovaries detached from the body wall and removed from the abdominal cavity would reestablish themselves when autografted to an ectopic site. In the first experiment, eleven sexually immature, female rainbow trout were laparotomized midventrally, and the right ovary was removed and transplanted to the abdominal cavity and positioned along the pyloric cecae on the right side. In the second experiment, the ovary was autografted in four animals as in experiment 1 or was transferred to and allografted in four other sexually immature female trout. The animals were examined three months following surgery. At the termination of experiment 1, the autografted ovaries were present in 73% of the animals; the transplanted ovaries were smaller in size than the intact control ovaries. Histological examination did not reveal any necrotic tissue in these transplanted gonads, and oocyte development was not different between the transplanted and the intact ovary within animal. Transplanted ovaries allografted from another female were not found. Taken together, these data support the conclusion that rainbow trout ovaries detached from the body wall can reestablish their blood supply and maintain ovarian development and that female trout appear to reject gonadal tissue from other individuals of their species. J. Exp. Zool. 73–76, 2003. © 2003 Wiley‐Liss, Inc.
Dopaminergic regulation of crustacean hyperglycemic hormone and glucose levels in the hemolymph of the crayfish Procambarus clarkii
Authors: Zou Hong‐Shin , Juan Chi‐Chih , Chen Shyh‐Chi , Wang Hsin‐Yuan , Lee Chi‐Ying
Published: June 2003

The effects of dopamine on crustacean hyperglycemic hormone (CHH) release and hemolymph glucose levels in the crayfish Procambarus clarkii were investigated. A quantitative sandwich enzyme‐linked immunosorbent assay (ELISA) using antibodies specific for Prc CHH was developed and characterized. The sensitivity of the ELISA was about 1 fmol/well. Specific measurement of CHH in hemolymph samples by the ELISA was demonstrated by the parallelism between CHH standard curve and sample (hemolymph) titration curve. Moreover, thermally stressed P. clarkii exhibited a characteristic change of hemolymph CHH levels as revealed by the ELISA. CHH and glucose levels increased significantly within 30 min of dopamine injection, peaked at 1 h, and returned to the basal levels at 4 h. Dose‐dependent effects of dopamine on CHH and glucose levels were observed between 10–8 to 10–6 mol/animal. Dopamine‐induced increases in CHH and glucose levels were absent in eyestalk‐ablated animals. Finally, dopamine significantly stimulated the release of CHH from in vitro incubated eyestalk ganglia. These results suggest that dopamine enhances release of CHH into hemolymph that in turn evokes hyperglycemic responses and that the predominant site of dopamine‐induced CHH release is the X‐organ‐sinus gland complex located within the eyestalk. J. Exp. Zool. 298A: 44–52, 2003. © 2003 Wiley‐Liss, Inc.
A degree‐two WR90 waveguide circulator using radial dielectric waveguide transformers
Authors: Hocine M. , Tsounis V. , Sharp J.
Published: June 2003

Most commercial degree‐two waveguide circulators using gyromagnetic turnstile and post resonators are quarter‐wave coupled by metal transformers. The purpose of this short paper is to experimentally describe one post‐resonator geometry using a self‐jigging, partially dielectric‐loaded radial waveguide transformer. The assembly developed in this work has a return loss of 20 dB and an insertion loss of 0.20 dB over a bandwidth of approximately 12% in the WR90 waveguide. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 263–264, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11033
Resonance characteristics of capacitively loaded CPW open‐loop resonators
Authors: Görür Adnan , Akgün Özlem
Published: June 2003

Capacitively loaded coplanar waveguide (CPW) open‐loop resonators (OLRs) are proposed for maximum miniaturization in uniplanar microwave applications. It is shown that these resonators can be used to achieve a slow‐wave effect without occupying extra surface area. Also, the resonators have a size reduction of about 50% at the same resonance frequency, as compared with the conventional open‐loop resonator, as well as a higher performance of about 25–30%. The reduction in size of these types of resonators, and their performance (mainly the Q factor), can be controlled by the fingers within the OLR. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 298–300, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11042
Dispersion characteristics of V‐shaped microstrip lines
Authors: Guo B. , Dong X. T. , Yin W. Y. , Gan Y. B.
Published: June 2003

The dispersion characteristics of the dominant mode in V‐shaped microstrip lines are investigated using the finite‐difference time‐domain (FDTD) method. Such V‐shaped microstrip lines are assumed to be fabricated on a single‐layer isotropic substrate. The hybrid effects of the inclined angle of the metal wall and the permittivity of the filling material on the effective permittivity and characteristic impedance are examined and compared. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 320–323, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11049
An extension of the array decomposition method for large finite‐array analysis
Authors: Kindt Rick , Sertel K. , Topsakal E. , Volakis J. L.
Published: June 2003

In this paper, a method is presented for analyzing very large finite arrays of tapered‐slot antenna elements. The Toeplitz matrix property of regularly spaced arrays, combined with a parametrically truncated coupling radius, generates fixed matrix storage based on the coupling radius rather than array size, thus allowing very large problem analysis. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 323–328, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11050
Radome‐protected low‐profile GSM antenna on small ground plane
Authors: Zaid Lakhdar , Staraj Robert
Published: June 2003

A small radiating element, designed to work in the GSM frequency band, made up entirely of square parts on air substrate is described. The dimensions of the ground plane are only 1.3 times the dimensions of the radiating element. By stacking two square wire patches, the characteristics of compactness, large bandwidth, and monopolar wire radiation pattern can be achieved. Circular designs have been already been presented, however, compared to the circular plates solution, the new structure described in this paper allows an easier realization as well as a protective dielectric radome. Owing to its low‐profile, low‐cost, and radioelectric properties such as large bandwidth and dipolar‐type radiation pattern, this antenna is very suitable for automobile or indoor ceiling applications which require a very small ground plane. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 328–331, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11051
Peri‐gastrulation development of the dasyurid marsupial Sminthopsis macroura (stripe‐faced dunnart) in vitro and evidence for patterning of the epiblast prior to gastrulation
Authors: Hickford Danielle , Selwood Lynne
Published: June 2003

Marsupials are potentially excellent models for the study of gastrulation because of their superficial embryonic area (EA), post‐gastrulation implantation and their potential to provide information about the evolution of gastrulation. Very few studies have examined this developmental period in marsupials. Using an established developmental timetable, peri‐gastrula stage Sminthopsis macroura blastocysts were collected and described in detail by observations on live blastocysts and by the use of histological and immunohistochemical techniques on fixed blastocysts. Gastrulation in S. macroura shares several aspects common to that of both eutherian mammals and birds, but in terms of tissue arrangement and conceptus form, is more similar to the chick than other mammals. Two methods of culturing EA explants flat without their shell were devised. The techniques will markedly increase the number of possible experimental manipulations, which previously were limited by the presence of blastocyst investments. Exposure of fractions of explants of round, morphologically uniform pre‐gastrula stage EA to growth factors or signaling molecules implicated in vertebrate gastrulation suggests that like the chick and mouse, the marsupial epiblast is patterned prior to gastrulation. Of all factors tested, basic fibroblast growth factor (bFGF) had the most prominent effect, promoting cell differentiation, and possible mesoderm formation. Data from explant culture suggests that similar to the chick and mouse, limited specification precedes the onset of gastrulation. Mol. Reprod. Dev. 65: 402–419, 2003. © 2003 Wiley‐Liss, Inc.
Effects on in vitro embryo development and intracellular glutathione content of the presence of thiol compounds during maturation of prepubertal goat oocytes
Authors: Rodríguez‐González Elisabet , López‐Bejar Manel , Mertens María‐José , Paramio María‐Teresa
Published: June 2003

The low number of embryos produced from in vitro matured, fertilized, and cultured (IVM–IVF–IVC) oocytes of prepubertal goat is mainly due to a low incidence of sperm head decondensation at fertilization (Martino et al., 1995: Theriogenology 43:473–485; Mogas et al., 1997: Theriogenology 48:815–829). Thiol compounds stimulate glutathione (GSH) synthesis and improve the rates of male pronucleus (MPN) formation and embryo development. The present study was carried out to determine whether supplementation of the IVM medium with 100 μM of cysteamine, 100 μM of β‐mercaptoethanol, 0.57 mM of cysteine, and 0.57 mM cystine might improve the embryo development and intracellular GSH level of prepubertal goat oocytes. After 27 hr post IVM, a sample of oocytes was frozen and the intracytoplasmic GSH content was evaluated by spectrophotometry. IVM‐oocytes were inseminated with fresh semen and cultured in SOF medium. Only the addition of cysteamine to IVM media significantly improved the percentage of the morula plus blastocyst yield compared to the control group (oocytes matured in absence of thiol compounds) (22.2 vs. 6.4%, respectively; P < 0.05). The percentage of expanded blastocysts in cysteamine and control groups was 13.0 and 2.6%, respectively, and the mean cell number per blastocyst was 86.8 and 60.5, respectively. None of the other thiol compounds studied significantly improved the percentage of embryos obtained. It has been demonstrated that prepubertal goat oocytes synthesize GSH during IVM and that thiol compounds increase this GSH synthesis. In conclusion, only the addition of 100 μM of cysteamine to the maturation medium improves embryo development from prepubertal goat oocytes although all the thiol compounds used in this study increased intracellular GSH content. Mol. Reprod. Dev. 65: 446–453, 2003. © 2003 Wiley‐Liss, Inc.
Bivariate spline method for numerical solution of time evolution Navier‐Stokes equations over polygons in stream function formulation
Authors: Lai Ming‐Jun , Liu Chun , Wenston Paul
Published: June 2003

We use a bivariate spline method to solve the time evolution Navier‐Stokes equations numerically. The bivariate splines we use in this article are in the spline space of smoothness r and degree 3r over triangulated quadrangulations. The stream function formulation for the Navier‐Stokes equations is employed. Galerkin's method is applied to discretize the space variables of the nonlinear fourth‐order equation, Crank‐Nicholson's method is applied to discretize the time variable, and Newton's iterative method is then used to solve the resulting nonlinear system. We show the existence and uniqueness of the weak solution in L2(0, T; H2(Ω)) ∩ L∞(0, T; H1(Ω)) of the 2D nonlinear fourth‐order problem and give an estimate of how fast the numerical solution converges to the weak solution. The C1 cubic splines are implemented in MATLAB for solving the Navier‐Stokes equations numerically. Our numerical experiments show that the method is effective and efficient. © 2003 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 19: 776–827, 2003.
Global business in the Middle East
Authors: Hanson David P.
Published: June 2003

W. Abdallah. 2001. Managing Multinationals in the Middle East: Accounting and Tax Issues.
Westport, CT: Quorum Press. 279 pages. ISBN 1‐56720‐267‐5.

M. Kavoossi. 2001. The Globalization of Business in the Middle East: Opportunities and
Constraints. Westport, CT: Quorum Press. 161 pages. ISBN 1‐56720‐203‐9.
China and the WTO: The implications of membership in historical context
Authors: Stoltenberg Clyde D.
Published: June 2003

China's accession to the WTO can be seen as the culmination of not just a 15‐year negotiation but
also of a process that actually began 150 years ago with the projection of Western imperialist power into the
Chinese mainland. China now appears to have joined the global community on mutually agreeable terms. The
commitments China has made are significant and, if implemented, will facilitate continued change in the
nation's legal/regulatory structure for economic growth. WTO accession has many implications, both
economic and political, for China and the rest of the world; it is important not to forget historical
context and current realities in assessing them. © 2003 Wiley Periodicals, Inc.
Dimer formation of subunit G of the yeast V‐ATPase
Authors: Armbrüster Andrea , Bailer Susanne M , Koch Michel H.J , Godovac-Zimmermann Jasminka , Grüber Gerhard
Published: June 2003

The G subunit of the vacuolar ATPase (V‐ATPase) is a component of the stalk connecting the V1 and VO sectors of the enzyme and is essential for normal assembly and function. Subunit G (Vma10p) of the yeast V‐ATPase was expressed in Escherichia coli as a soluble protein and was purified to homogeneity. The molecular mass of subunit G, determined by Native‐polyacrylamide gel electrophoresis, gel filtration analysis and small‐angle X‐ray scattering, was approximately 28±2 kDa, indicating that this protein is dimeric. With a radius of gyration (R
g) and a maximum size (D
max) of 2.7±0.2 nm and 8.0±0.3 nm, respectively, the G‐dimer is rather elongated. To understand which region of subunit G is required to mediate dimerization, a G38–144 form (the carboxyl‐terminus) was expressed and purified. G38–144 is homogeneous, with a molecular mass of approximately 12±3 kDa, indicating a monomeric form in solution.
Sphingomyelin is much more effective than saturated phosphatidylcholine in excluding unsaturated phosphatidylcholine from domains formed with cholesterol
Authors: van Duyl Bianca Y. , Ganchev Dragomir , Chupin Vladimir , de Kruijff Ben , Killian J.Antoinette
Published: June 2003

In this study, we compared domain formation in raft‐like mixtures of cholesterol and dioleoylphosphatidylcholine (DOPC) with either sphingomyelin (SM) or dipalmitoylphosphatidylcholine (DPPC). Using 2H nuclear magnetic resonance, we studied the properties of the lipid enriched in the fluid phase, DOPC. We found that acyl chain 2H‐labeled DOPC is much less ordered in SM‐containing mixtures than in those containing DPPC, suggesting that DOPC in the SM‐containing mixture senses a lower concentration of cholesterol in its direct environment. Atomic force microscopy experiments demonstrated large differences in the size and shape of domains in the different mixtures. We propose that these various differences are a consequence of the preferential interaction of cholesterol for sphingolipids over glycerophospholipids.
The room temperature emission band shape of the lowest energy chlorophyll spectral form of LHCI
Authors: Jennings Robert C , Garlaschi Flavio M , Engelmann Enrico , Zucchelli Giuseppe
Published: June 2003

Selective excitation, at room temperature, in the long wavelength absorption tail of the photosystem I antenna complexes, known as light harvesting complex I, induces pronounced pre‐equilibration fluorescence from the directly excited pigment state. This has allowed determination of the fluorescence band shape of this low energy photosystem I chlorophyll antenna state, at room temperature, for the first time. The emission maximum is near 735 nm. The remarkable band width (55 nm) and asymmetry have never been previously reported for chlorophyll a states.
Overexpression of cytosolic sialidase Neu2 induces myoblast differentiation in C2C12 cells
Authors: Fanzani A. , Giuliani R. , Colombo F. , Zizioli D. , Presta M. , Preti A. , Marchesini S.
Published: June 2003

Cytosolic sialidase Neu2 has been implicated in myoblast differentiation. Here we observed a significant upregulation of Neu2 expression during differentiation of murine C2C12 myoblasts. This was evidenced both as an increase in Neu2 mRNA steady‐state levels and in the cytosolic sialidase enzymatic activity. To understand the biological significance of Neu2 upregulation in myoblast differentiation, C2C12 cells were stably transfected with the rat cytosolic sialidase Neu2 cDNA. Neu2 overexpressing clones were characterized by a marked decrement of cell proliferation and by the capacity to undergo spontaneous myoblast differentiation also when maintained under standard growth conditions. This was evidenced by the formation of myogenin‐positive myotubes and by a significant decrease in the nuclear levels of cyclin D1 protein. No differentiation was on the contrary observed in parental and mock‐transfected cells under the same experimental conditions. The results indicate that Neu2 upregulation per se is sufficient to trigger myoblast differentiation in C2C12 cells.
Laparoscopic oxidized cellulose (Surgicel) application for small uterine perforations
Authors: Sharma J.B. , Malhotra M. , Pundir P.
Published: June 2003

Objectives: To test the efficacy and safety of laparoscopic oxidized cellulose application at the uterine perforation site. Methods: In a prospective study over a 3.5‐year period a total of 30 women undergoing combined surgical termination of pregnancy and laparoscopic sterilization who had a small uterine perforation were recruited. Oxidized cellulose (Surgicel) was inserted and attached to the perforation site with a laparoscope. The end point was sealing of the perforation and complete hemostasis. Laparotomy was performed if hemostasis was not achieved. Results: The mean age, parity and gestation were 31.4 years, 3.8 and 9.3 weeks. The perforations occurred in the fundal region (60%), anterior wall (16.7%), posterior wall (13.3%), upper lateral wall (3.3%) and lower lateral wall (6.7%). Mean size of perforations, respectively according to site were 4.3 mm, 3.2 mm, 3.4 mm, 3mm and 3.5 mm in the five groups. Laparoscopic oxidized cellulose application was successful in all women with fundal, anterior, posterior and upper lateral uterine wall perforations. In two women with perforations on the lower lateral wall, due to excessive blood loss, oxidized cellulose fell off; laparotomy was performed and hemostasis was achieved with sutures. All 28 laparoscopically‐treated women were discharged on the next day in good condition with no complications. Conclusions: Laparoscopic oxidized cellulose application appears to be a safe and effective treatment for small uterine perforations that are bleeding moderately.
On critical exponents for the Pucci’s extremal operators
Authors: Felmer Patricio L. , Quaas Alexander
Published: June 2003

In this article we study some results on the existence of radially symmetric, non-negative solutions for the nonlinear elliptic equation

\tag{$*$}
\mathcal M_{\lambda ,\Lambda }^{ + }\left(D^{2}u\right) + u^{P} = 0 \quad \text{in }\mathbb{R}^{N}.

Here

N⩾3

,

p>1

and

\mathcal M_{\lambda ,\Lambda }^{ + }

denotes the Pucci’s extremal operators with parameters

0<λ⩽Λ

. The goal is to describe the solution set in function of the parameter 

p

. We find critical exponents

1 < p_{ + }^{*} < p_{ + }^{p}

that satisfy: (i) If

1 < p < p_{ + }^{*}

then there is no non-trivial radial solution of (

*

). (ii) If

p = p_{ + }^{*}

then there is a unique fast decaying radial solution of (

*

). (iii) If

p_{ + }^{*} < p \leq p_{ + }^{p}

then there is a unique pseudo-slow decaying radial solution to (

*

). (iv) If

p^p_+
1

et

\mathcal M_{\lambda ,\Lambda }^{ + }

est l’opérateur extrémal de Pucci avec les paramètres

0<λ⩽Λ

. L’objectif est de décrire l’ensemble des solutions en fonction de

p

. On trouve des exposants critiques

1 < p_{ + }^{*} < p_{ + }^{p}

tels que : (i) Si

1 < p < p_{ + }^{*}

, alors il n’existe pas de solution radiale non triviale de (

*

). (ii) Si

p = p^∗_+

, il existe une unique solution radiale de (

*

) à décroissance rapide. (iii) Si

p^*<p⩽p^p_+

, il existe une unique solution radiale de (

*

) à décroissance pseudo-lente. (iv) Si

p^p_+<p

, il existe une unique solution radiale de (

*

) à décroissance lente.

Un résultat similaire est obtenu pour l’opérateur 

\mathcal M_{\lambda ,\Lambda }^{ - }

.
Permanence under strong aggressions is possible
Authors: Cano-Casanova Santiago , López-Gómez Julián
Published: June 2003

This paper analyzes the limiting behavior of the positive solutions of a general class of sublinear elliptic weighted mixed boundary value problems as the amplitude of the positive part of the lower order terms of the differential operator blows up to infinity. The main result establishes that the positive solutions approximate zero within the support of the positive part of the potential, whereas they stabilize to the positive solution of a certain elliptic mixed boundary value problem on its complement. Further, we use this result for deriving some general principles in competing species dynamics. Precisely, we shall show that in the presence of a refuge region two competing species must coexist if their reproduction rates are sufficiently large, independently of the strength of the competition. It should be emphasized that the abstract theory developed here allows measuring how large the reproduction rates should be for being permanent, providing us, simultaneously, with the limiting behavior of each of the species separately. Basically, when the pressure from the competitor grows the tackled species concentrates within its refuge. The results of this paper are substantial extensions of some pioneer results found by one of the authors in [16, Section 4]. The main ingredients in deriving the main results of this paper are the continuous dependence of the principal eigenvalue with respect to a general class of perturbations of the domain around its Dirichlet boundary – very recent result coming from [6] – and the continuous dependence of the positive solutions of the sublinear problem – coming from [7].

On étudie le comportement asymptotique des solutions positives d’une classe très générale de problèmes aux limites non linéaires elliptiques lorsque l’amplitude du potentiel d’ordre zéro de l’opérateur différentiel tend vers l’infini. En particulier, on verra que la solution tend vers zéro sur le support de la partie positive du potentiel, tandis qu’elle converge vers la solution positive d’un certain problème aux limites elliptiques auxiliaires sur la région ou le potentiel est nul. De plus, on va tirer de ce résultat de convergence un postulat biologique concernant la lutte pour la vie des espèces qui s’entredévorent : indépendamment de l’intensité des agressions, en présence d’un refuge pour chaque compétiteur les espèces coexistent si leurs coefficients d’accroissement sont assez longs. Il faut préciser qu’avec la théorie développée ici on peut mesurer le coefficient d’accroissement critique des espèces pour avoir la coexistence. Naturellement, l’espèce agressée va se concentrer sur les refuges correspondants si l’intensité des agressions croı̂t. Tous les résultats obtenus ici sont des généralisations substantielles des résultats [16, Section 4]. Pour démontrer ces résultats on utilise la dépendance continue de la première valeur propre, et de la solution positive même du problème aux limites non linéaire, par rapport aux perturbations du domaine (cf. [6] et [7]).
Distribution of in situ forces in the anterior cruciate ligament in response to rotatory loads
Authors: Gabriel Mary T. , Wong Eric K. , Woo Savio L‐Y. , Yagi Masayoshi , Debski Richard E.
Published: June 2003

The anterior cruciate ligament (ACL) can be anatomically divided into anteromedial (AM) and posterolateral (PL) bundles. Current ACL reconstruction techniques focus primarily on reproducing the AM bundle, but are insufficient in response to rotatory loads. The objective of this study was to determine the distribution of in situ force between the two bundles when the knee is subjected to anterior tibial and rotatory loads. Ten cadaveric knees (50 ± 10 years) were tested using a robotic/universal forcemoment sensor (UFS) testing system. Two external loading conditions were applied: a 134 N anterior tibial load at full knee extension and 15°, 30°, 60°, and 90° of flexion and a combined rotatory load of 10 N m valgus and 5 N m internal tibial torque at 15° and 30° of flexion. The resulting 6 degrees of freedom kinematics of the knee and the in situ forces in the ACL and its two bundles were determined. Under an anterior tibial load, the in situ force in the PL bundle was the highest at full extension (67 ± 30 N) and decreased with increasing flexion. The in situ force in the AM bundle was lower than in the PL bundle at full extension, but increased with increasing flexion, reaching a maximum (90 ± 17 N) at 60° of flexion and then decreasing at 90°. Under a combined rotatory load, the in situ force of the PL bundle was higher at 15° (21 ± 11 N) and lower at 30° of flexion (14 ± 6 N). The in situ force in the AM bundle was similar at 15° and 30° of knee flexion (30 ± 15 vs. 35 ± 16 N, respectively). Comparing these two external loading conditions demonstrated the importance of the PL bundle, especially when the knee is near full extension. These findings provide a better understanding of the function of the two bundles of the ACL and could serve as a basis for future considerations of surgical reconstruction in the replacement of the ACL. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Pre‐degenerated nerve shows enhanced regeneration after incremental elongation in rats
Authors: Hara Yuki , Tsujino Akihito , Abe Ichiro , Ichimura Harumitsu , Ochiai Naoyuki
Published: June 2003

Following nerve degeneration, we investigated effects of linear elongation on subsequent nerve regeneration in a total of 92 Wistar rats (weight 380–340 g). The nerve was ligated at the midthigh and then elongated incrementally by a total of 15 mm by leg lengthening at a rate of 3 or 5 mm/day. Seven days after initiation of nerve elongation, the external fixator was removed and normal leg length was restored with internal fixation. Then a 10 mm nerve segment at the ligature site was excised, and the nerve was repaired with sutures (group D). At 2, 4, 6, and 8 weeks after nerve suturing, we examined transverse semi‐thin nerve sections compared with group I (severed and repaired after leg lengthening without a nerve ligature) and control group (severed and repaired without leg lengthening). After lengthening at 3 mm/day, nerve regeneration in group D was enhanced at 4 weeks. After lengthening at 5 mm/day, nerve regeneration in group D also was enhanced at 6 and 8 weeks. Pre‐degenerated nerve showed better regeneration after suturing than intact nerve. Elongation holds promise as an alternative to nerve grafting in treatment of nerve injury. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Evaluation of the absolute levels of acoustic estimates of the 1983 year class of Norwegian spring-spawning herring
Authors: Røttingen Ingolf , Tjelmeland Sigurd
Published: June 2003

The 1983 year class of Norwegian spring-spawning herring was large and, in retrospect, increased the spawning stock by more than two million tons when it recruited in 1987–1988. This paper summarizes and evaluates the acoustic estimates of the 1983 year class in the period 1983–2001. The key to the evaluation is a minimum stock based on the number of the 1983 year class caught in the international fishery and the year-class estimates made by the ICES Northern Pelagic and Blue Whiting Fisheries Working Group in 2002 using the SeaStar assessment model. The period of analysis covers a change in instrumentation, around 1990, from the SIMRAD EK400/Nord integrator to the EK500/BEI integrator system. The application of the acoustic estimates in the assessment and management of this herring stock is reviewed. It is concluded that the stock size was underestimated when the acoustic estimates were used in an absolute sense in the 1980s. In the 1990s the acoustic estimates were tuned to stock-size indices obtained from other methodologies and this approach seems to have given a realistic picture of the development of the 1983 year class.
Inferring fish orientation from broadband-acoustic echoes
Authors: Stanton Timothy K , Reeder D.Benjamin , Jech J.Michael
Published: June 2003

A new method has been developed for inferring the orientation of fish through the use of broadband-acoustic signals. The method takes advantage of the high range resolution of these signals, once temporally compressed through cross-correlation. The temporal resolution of these compressed signals is inversely proportional to the bandwidth, thus the greater the bandwidth the higher the resolution. This process has been applied to broadband-chirp signals spanning the frequency range 40–95 kHz to obtain a range resolution of approximately 2 cm from the original, unprocessed resolution of about 50 cm. With such high resolution, individual scattering features along the fish have been resolved, especially for angles well off normal incidence. The overall duration of the compressed echo from live, individual alewife, as measured in a laboratory tank, is shown to increase monotonically with orientation angle relative to normal incidence. The increase is due to the greater range separation relative to the transducer between the echoes from the head and tail of the fish. The results of this study show that with a priori knowledge of the length of the fish, the orientation could be estimated from the duration of a single, compressed broadband echo. This method applies to individual, acoustically resolved fish. It has advantages over previous approaches because it derives the orientation from a single ping and it does not use a formal, mathematical scattering model. Design parameters for applications in the ocean are given for a range of conditions and fish size.
Ex situ target strength of rockfish (Sebastes schlegeli) and red sea bream (Pagrus major) in the Northwest Pacific
Authors: Kang Donhyug , Hwang Doojin
Published: June 2003

This study determined the ex situ target strength (TS) of rockfish (Sebastes schlegeli) and red sea bream (Pagrus major) in an artificial seawater tank as a means of helping to estimate fishery resources in coastal areas. TS experiments were conducted at frequencies of 38 kHz (split beam), 120 kHz (split beam), and 200 kHz (dual beam). The species were examined under two conditions: first, live fish confined to a small, net cage; and, second, as free-swimming fish inside a large tank. The study examined 21 rockfish and 20 red sea bream. The data were used to obtain expressions for TS against length and weight for the two species. The relationships between TS and fish length were as follows: for rockfish, TS38 kHz = 20 log10(L) − 67.7 (r = 0.80), TS120 kHz = 20 log10(L) − 74.3 (r = 0.61), TS200 kHz = 20 log10(L) − 72.8 (r = 0.41); and for red sea bream, TS38 kHz = 20 log10(L) − 66.8 (r = 0.86), TS120 kHz = 20 log10(L) − 74.0 (r = 0.65), TS200 kHz = 20 log10(L) − 74.1 (r = 0.83). The TS equations for rockfish and red sea bream as a function of fish weight at 38 kHz were TS38 kHz = 6.75 log10(W) − 56.0 (r = 0.78) and TS38 kHz = 4.08 log10(W) − 49.9 (r = 0.89), respectively. For comparison, calculations using the Helmholtz–Kirchhoff ray-approximation model based on swimbladder morphology were compared with the measured TS. When the tilt angle of the fish is zero, the mean TS from the model is 3–10 dB higher than the experimental results, although the maximum TS values were only 3–4 dB different.
Mixture models for the species apportionment of hydroacoustic data, with echo-envelope length as the discriminatory variable
Authors: Fleischman Steve J , Burwen Debby L
Published: June 2003

For this side-looking, 200 kHz, split-beam sonar application, echo-envelope length has been shown to be predictive of fish size. In this study, this relationship is exploited to estimate the abundance of (large) chinook salmon (Oncorhynchus tshawytscha) in the presence of (smaller) sockeye salmon (Oncorhynchus nerka). The echo-length to fish-size relationship is too imprecise to ascertain the species of individual fish in the classic sense. However, the frequency distribution of echo-length measurements contains information on the relative abundance of chinook and sockeye salmon. The use of echo-length measurements in a mixture model is explored in order to estimate the proportion of total fish passage that comprised chinook salmon. Inputs to the model include empirical estimates of the length–frequency distribution for each species, parameter estimates from the regression relationship of echo-length to fish-length, and echo-length measurements from individual, ensonified fish. Outputs are estimates of the proportions of chinook and sockeye salmon in the river. The advantages of the mixture-model approach over threshold-based discrimination are discussed. Conditional maximum likelihood and Bayesian versions of the model are described. The method can be generalized to other hydroacoustic measurements, including target strength and other discrimination problems.
Acoustic observation and assessment of fish in high-relief habitats
Authors: Cooke K , Kieser R , Stanley R.D
Published: June 2003

Acoustics present an alternative sampling strategy in areas characterized by steep slopes and rugged terrain where fishing is impractical. However, when the interference between echoes from fish targets and boundaries is severe, acoustic observations require careful interpretation of the echo returns. This article outlines a method of generating a representative 3D model of the bottom topography that can assist in near-boundary fish discrimination. Images provide greater insight to echo source and highlight some of the difficulties associated with classifying acoustic sign. The results emphasize the importance of good survey design aimed at minimizing side-lobe interference and reducing acoustic-shadow zones.