bluuebunny/crossref_metadata_2025 huggingface dataset:
Treatment of unresectable malignant rhabdoid tumor of the orbit with tandem high‐dose chemotherapy and gamma‐knife radiosurgery
Authors: Watanabe Hiroyoshi , Watanabe Tsutomu , Kaneko Michiya , Suzuya Hiroko , Onishi Toshihiro , Okamoto Yasuhiro , Miyake Hajime , Yasuo Kensaku , Hirose Takanori , Kagami Shoji
Published: March 2006

Malignant rhabdoid tumor (MRT) is a rare and highly aggressive tumor that primarily occurs in very young children. We report here a patient with a primary MRT of the orbit who received tandem high‐dose chemotherapy and gamma‐knife radiosurgery. Although the tumor was not completely removed, and the initial chemotherapy failed, the patient achieved long‐term survival after this modality of treatment. This approach may be one to be further considered in patients with MRT. Pediatric Blood Cancer 2006;47:846–850. © 2006 Wiley‐Liss, Inc.
Clinical appearance of neuroblastoma 10 years after screening
Authors: Kerbl Reinhold , Urban Christian E. , Zotter Heinz , Lackner Herwig , Sovinz Petra , Ambros Peter F.
Published: March 2006

A follow‐up study was performed for children with previous repeated positive results by neuroblastoma mass screening and negative clinical results (30 out of 439,128 children screened in Austria between 1991 and 2003, median follow‐up 113 months). Four children had continuously elevated urine catecholamines for more than 6 months. One of these patients was diagnosed with pelvic neuroblastoma and multiple metastases 10 years after the first positive screening result. In the light of a ‘wait and see’ strategy for localized neuroblastomas, our observation suggests that these patients should be further observed even after normalization of urine catecholamines. Pediatr Blood Cancer 2007;49:1012–1014. © 2006 Wiley‐Liss, Inc.
Synthesis and characterization of polyurethane/montmorillonite nanocomposites by in situ polymerization
Authors: Ding Qingjun , Liu Baolei , Zhang Qiang , He Qihui , Hu Baixing , Shen Jian
Published: March 2006

In this paper, a new type of organophilic montmorillonite, co‐treated with cetyltrimethyl ammonium bromide (CTAB) and 4,4′‐diphenymethylate diisocyanate (MDI), was modified and applied to prepare polyurethane/montmorillonite nanocomposites via in situ polymerization. The nanoscale montmorillonite layers were exfoliated and dispersed relatively homogeneously in the polyurethane matrix, and characterized by X‐ray diffraction and transmission electron microscopy. The thermal degradation temperature of the nanocomposites increased, as compared with pristine polyurethane. Dynamic mechanical analysis confirmed the constraining effect of exfoliated montmorillonite layers on polyurethane chains, which benefited the increased storage modulus and increased glass transition temperature. Tensile tests showed that the exfoliated nanocomposites were reinforced and toughened by the addition of nanometer‐size montmorillonite layers. Copyright © 2006 Society of Chemical Industry
Dehydration of ethanol/water mixtures by pervaporation using soluble polyimide membranes
Authors: Li Chi‐Lan , Lee Kueir‐Rarn
Published: March 2006

A series of soluble polyimides derived from 3,3′,4,4′‐benzhydrol tetracarboxylic dianhydride (BHTDA) with various diamines such as 1,4‐bis(4‐aminophenoxy)‐2‐tert‐butylbenzene (BATB), 1,4‐bis(4‐aminophenoxy)‐2,5‐di‐tert‐butylbenzene (BADTB), and 2,2′‐dimethyl‐4,4′‐ bis(4‐aminophenoxy)biphenyl (DBAPB) were investigated for pervaporation separation of ethanol/water mixtures. Diamine structure effect on the pervaporation of 90 wt% aqueous ethanol solution through the BHTDA‐based polyimide membranes was studied. The separation factor ranked in the following order: BHTDA–DBAPB > BHTDA–BATB > BHTDA–BADTB. The increase in molecular volume for the substituted group in the polymer backbone increased the permeation rate. As the feed ethanol concentration increased, the permeation rate increased, while the water concentration in the permeate decreased for all polyimide membranes. The optimum pervaporation performance was obtained by the BHTDA–DBAPB membrane with a 90 wt% aqueous ethanol solution, giving a separation factor of 141, permeation rate of 255 g m−2 h−1 and 36 000 pervaporation separation index (PSI) value. Copyright © 2006 Society of Chemical Industry
Structural effects of type of intercalant in poly (4‐vinylpyridine) nanocomposites: compatible homopolymer or block copolymer
Authors: Şen Sinan , Nugay Nihan , Nugay Turgut
Published: March 2006

4‐vinylpyridine monomer was mixed with organophilic montmorillonite (MMT) clay and polymerized in the presence of free‐radical initiator. MMT clay was rendered organophilic by means of ion‐exchanging sodium cations for low‐molecular‐weight quaternized poly(4‐vinylpyridine) (P4VP) homopolymer and diblock copolymers of styrene and quaternized 4‐vinylpyridine (SVP) with different sequence lengths. The swelling behaviour of the MMT clay was studied by X‐ray diffraction (XRD). After the cation exchange, the resulting organophilic clays showed an expansion of interlayer distance indicating the nanoscale ordering of intercalant polymer and MMT layers. The nanocomposite materials, when moulded, exhibited improved thermal stability and dynamic mechanical properties compared with neat P4VP. The composite, having longer ionic segments in its organophilic MMT, showed exfoliated nanocomposite structure as well as higher stiffness and damping properties at higher temperatures even for MMT loading as low as 2 wt%. Copyright © 2006 Society of Chemical Industry
A photo‐dependent capacitance model of GaAs MESFET's
Authors: Narasimha Murty Neti V. L. , Jit S.
Published: March 2006

A new and simple analytical model for determining the photo‐effects on the gate–source and gate–drain capacitances of GaAs MESFET's has been presented for both the linear and saturation regions. A new model for the photovoltage developed across the Schottky junction due to the illumination has been used to investigate the photo‐dependent characteristics of the above capacitances. It has been observed that the gate–source and gate–drain capacitances are increased with the increase in the incident illumination level to the device in its linear region of operation whereas in the saturation region, the gate–source capacitance is increased but the gate–drain capacitance is observed to be decreased with the increase in the incident optical intensity level. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical study of improved two‐dimensional electron gas density in AlGaN/GaN/AlGaN double heterostructure
Authors: Kong Y. C. , Chu R. M. , Zheng Y. D. , Zhou C. H. , Shen B. , Gu S. L. , Zhang R. , Han P. , Shi Y. , Jiang R. L.
Published: March 2006

We evaluate the Alx Ga1–x N/GaN/Aly Ga1–y N double heterostructure (DH) for heterostructure field‐effect transistor applications, where the GaN quantum well is compressively strained on a relaxed crack‐free Aly Ga1–y N buffer layer, so that the Al content in the Alx Ga1–x N top barrier can be improved as compared with a conventional Alx Ga1–x N/GaN single heterostructure (SH) with the same strain in the Alx Ga1–x N layer. By self‐consistently solving the coupled Schrödinger and Poisson equations, we find that the two‐dimensional electron gas (2DEG) sheet density in an Al0.6Ga0.4N/GaN/Al0.3Ga0.7N DH is 2.59 × 1013 cm–2, much higher than the 1.71 × 1013 cm–2 in a conventional Al0.3Ga0.7N/GaN SH. The 2DEG sheet density increases with increasing Al content x and decreases slightly with increasing y . With a fixed Al content (x – y ) ratio, y is the key parameter determining the 2DEG density. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thickness dependent morphology and resistivity of ultra‐thin Al films grown on Si(111) by molecular beam epitaxy
Authors: Aswal D. K. , Joshi N. , Debnath A. K. , Gupta S. K. , Vuillaume D. , Yakhmi J. V.
Published: March 2006

The morphology and electrical resistivity of ultrathin Al metal films grown on (111) Si substrates using molecular‐beam epitaxy have been investigated. For thickness <60 nm, the film morphology consists of a two‐dimensional network of Al islands, which grows via Volmer–Weber mechanism. The coalescence of islands is found to begin at a thickness of 60 nm. The room‐temperature value of resistivity, contrary to the theoretical predictions of existing models, is found to increase monotonically with thickness. Also the temperature dependence of these films exhibited a metal‐to‐insulator transition at 110 K. The anomalous temperature dependences of resistivity have been explained using a two‐dimensional variable range hopping conduction (2d‐VRH) mechanism. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mesoscopic transport in carbon nanotubes: novel features
Authors: Latil S. , Roche S. , Triozon F. , Jiang J. , Saito R.
Published: March 2006

We report on novel mesoscopic transport features in carbon nanotubes. First, giant fluctuations of magnetotransport fingerprints are analyzed in boron‐doped carbon nanotubes. Depending on the energy of charge carries and applied magnetic field transport regime can be tuned from ballistic‐like to strongly diffusive, with a superimposed unbalanced contribution of quantum interference effects. Second the role of electron–phonon dephasing on conductance scaling is studied. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Kondo effect in nanostructures
Authors: Pustilnik M.
Published: March 2006

Kondo effect arises whenever a coupling to the Fermi gas induces transitions within the otherwise degenerate ground state multiplet of an interacting system. Both coupling to the Fermi gas and interactions are naturally present in any nanoscale transport experiment. At the same time, many nanostructures can easily be tuned to the vicinity of a degeneracy point. This is why the Kondo effect in its various forms often influences the low temperature transport in meso‐ and nanoscale systems.

In this short review we discuss the basic physics of the Kondo effect and its manifestations in the lowtemperature electronic transport through a single electron transistor. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Computational and spectroscopic studies concerning the solvatochromic behavior of 1,3‐disubstituted azulenes
Authors: Blice‐Baum Anna , Van Dyke Aaron , Sigmon Ian , Salter E. Alan , Wierzbicki Andrzej , Pocker Y. , Spyridis Greg T.
Published: March 2006

Estimates of excited‐state dipole moments for various 1,3‐disubstituted azulenes possessing electron‐withdrawing substituents, using the CIS/6‐31+G(d,p) model, reveal that unlike azulene, the excited‐state dipole moments are generally in the same direction as, although smaller in magnitude than, their ground‐state counterparts. This gives rise to hypsochromic shifts in the UV‐visible spectrum of these dipolar indicator molecules as solvent polarity is increased. Furthermore, B3LYP density functional calculations on several 1,3‐diacylazulenes indicate that the s‐cis conformation is preferred over s‐trans. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
New short peptaibols from a marine Trichoderma strain
Authors: Mohamed‐Benkada Mustapha , Montagu Monique , Biard Jean‐François , Mondeguer Florence , Verite Philippe , Dalgalarrondo Michèle , Bissett John , Pouchus Yves François
Published: March 2006

The production of peptaibols by a marine‐related Trichoderma longibrachiatum strain was studied using electrospray ionisation multiple‐stage ion trap mass spectrometry (ESI‐MSn‐IT) and gas chromatography/electron impact mass spectrometry (GC/EI‐MS). Two major groups of peptaibols were identified, those with long sequences (20 amino acids) and others with short sequences (11 amino acids). This paper describes the methodology used to establish the sequences of short peptaibols in a mixture without previous individual separation. Nine peptaibols were identified. Among them, eight are new, namely as trichobrachin A I–IV (Aib9‐Pro10 sequence) and as trichobrachin B I–IV (Val9‐Pro10 sequence). Original Pro6‐Val7 and Val9‐Pro10 sequences have to be noted. Copyright © 2006 John Wiley & Sons, Ltd.
Use of flow injection atmospheric pressure photoionization quadrupole time‐of‐flight mass spectrometry for fast olive oil fingerprinting
Authors: Gómez‐Ariza J. L. , Arias‐Borrego A. , García‐Barrera T.
Published: March 2006

The recently introduced technique of an atmospheric pressure photoionization (APPI) source coupled to quadrupole time‐of‐flight mass spectrometry (QqTOFMS) has been applied to fast olive oil fingerprinting on the basis of the accurate mass measurements obtained with this instrumentation. The key compounds can be characterized as [M+H]+ (produced by proton transfer) or as [M]+. (by charge transfer) ions in the mass spectra. [M+H]+ ions, however, show higher abundance, especially for triacylglycerols. Other ions present in APPI‐MS are the acylium ion [RiCO]+ and [RiCOH2O]+. This latter ion is absent in the electrospray ionization (ESI)‐MS spectra, and this represents valuable complementary information. Several critical parameters in the APPI source were optimized such as LC eluent composition, ion spray voltage and, especially, declustering potential. APPI‐QqTOFMS allows easy discrimination among different edible oils: olive, extra virgin olive, olive‐pomace, hazelnut, sunflower, corn and several mixed oils, with high throughput (approximately 1 min per sample). Cluster analysis was applied to obtain the best experimental conditions for oil discrimination on the basis of declustering potential. Principal components analyses of these APPI‐MS spectra show that the approach can be used for studies of olive oil adulteration with other oils, even in the case of hazelnut oil that exhibits a high chemical similarity with olive oil. Copyright © 2006 John Wiley & Sons, Ltd.
RT‐PSM, a real‐time program for peptide‐spectrum matching with statistical significance
Authors: Wu Fang‐Xiang , Gagné Pierre , Droit Arnaud , Poirier Guy G.
Published: March 2006

The analysis of complex biological peptide mixtures by tandem mass spectrometry (MS/MS) produces a huge body of collision‐induced dissociation (CID) MS/MS spectra. Several methods have been developed for identifying peptide‐spectrum matches (PSMs) by assigning MS/MS spectra to peptides in a database. However, most of these methods either do not give the statistical significance of PSMs (e.g., SEQUEST) or employ time‐consuming computational methods to estimate the statistical significance (e.g., PeptideProphet). In this paper, we describe a new algorithm, RT‐PSM, which can be used to identify PSMs and estimate their accuracy statistically in real time. RT‐PSM first computes PSM scores between an MS/MS spectrum and a set of candidate peptides whose masses are within a preset tolerance of the MS/MS precursor ion mass. Then the computed PSM scores of all candidate peptides are employed to fit the expectation value distribution of the scores into a second‐degree polynomial function in PSM score. The statistical significance of the best PSM is estimated by extrapolating the fitting polynomial function to the best PSM score. RT‐PSM was tested on two pairs of MS/MS spectrum datasets and protein databases to investigate its performance. The MS/MS spectra were acquired using an ion trap mass spectrometer equipped with a nano‐electrospray ionization source. The results show that RT‐PSM has good sensitivity and specificity. Using a 55 577‐entry protein database and running on a standard Pentium‐4, 2.8‐GHz CPU personal computer, RT‐PSM can process peptide spectra on a sequential, one‐by‐one basis in 0.047 s on average, compared to more than 7 s per spectrum on average for Sequest and X!Tandem, in their current batch‐mode processing implementations. RT‐PSM is clearly shown to be fast enough for real‐time PSM assignment of MS/MS spectra generated every 3 s or so by a 3D ion trap or by a QqTOF instrument. Copyright © 2006 John Wiley & Sons, Ltd.
Protonation thermochemistry of aminoacetonitrile
Authors: Bouchoux Guy , Guillemin Jean‐Claude , Lemahieu Nadège , McMahon Terrance B.
Published: March 2006

The gas‐phase basicity (GB) of aminoacetonitrile (NH2CH2CN, 1) has been determined from measurement of proton transfer equilibrium constants in an ion cyclotron resonance mass spectrometer (GB(1) = 789.3 ± 1.0 kJ · mol−1). Molecular orbital calculations up to the G2 level demonstrate that protonation occurs preferentially on the nitrogen atom of the NH2 group, and provide a theoretical proton affinity (PA(1)) of 824.0 kJ · mol−1. Exact calculation of the entropy associated with hindered rotations and consideration of Boltzman distribution of conformers allow a theoretical estimate of the molar protonation entropy S°(1H+) − S°(1) = 8.6 J · mol−1 · K−1. Combining this value with experimental GB(1) leads to an ‘experimental’ proton affinity of 819.2 kJ · mol−1, in close agreement with the G2 expectation. Copyright © 2006 John Wiley & Sons, Ltd.
Enhanced mass resolution method development, validation and assay application to support preclinical studies of a new drug candidate
Authors: Pucci Vincenzo , Bonelli Fabio , Monteagudo Edith , Laufer Ralph
Published: March 2006

A very highly sensitive and highly selective liquid chromatographic/tandem mass spectrometric (LC/MS/MS) method was developed to evaluate and quantify a new drug candidate in different biological matrices. Following a simple plasma protein precipitation using acetonitrile, the post‐treatment samples were analyzed on a C18 column interfaced with a new generation of triple‐quadrupole mass spectrometer. The recently introduced triple‐quadrupole mass spectrometer, the TSQ Quantum Ultra, with enhanced mass‐resolution capability, demonstrated improved sensitivity (0.05 ng/mL), coupled with suitable accuracy and precision, over a broad linear dynamic range (0.05–1000 ng/mL). A comparison of the assay performance data (dynamic range, calibration curve equation, precision and accuracy) of the enhanced resolution method against a unit resolution method under optimized conditions showed the performance improvement of the enhanced mass resolution method for bioanalytical high‐throughput applications. The enhanced mass resolution method herein described was successfully applied to the evaluation of the pharmacokinetic profile of a new drug candidate in rat, rabbit and dog plasma samples. Copyright © 2006 John Wiley & Sons, Ltd.
Complex formation between a tetramesityl sulfonated resorcarene and alkylammonium ions: a mass spectrometric study of noncovalent interactions
Authors: Ventola Elina , Hyyryläinen Anna , Vainiotalo Pirjo
Published: March 2006

Noncovalent complex formation between a tetramesityl sulfonated tetramethyl resorcarene and primary, secondary, and tertiary alkylammonium ions was investigated by electrospray ionization (ESI) Fourier transform ion cyclotron resonance (FT‐ICR) mass spectrometry. Competition measurements, collision‐induced dissociation, and gas‐phase hydrogen/deuterium (H/D)‐exchange reactions were employed to elucidate the interactions involved in complexation, the stability of the complexes, and the position of the guest with relation to the resorcarene. The complex formation ability of tetramesityl sulfonated resorcarene and the stability of the compexes were compared with the corresponding properties of tetratosylium tetraethyl resorcarene, which has been studied previously. Complex formation and the properties of the complexes were most strongly determined by the steric properties of the guests and their ability to form hydrogen bonds. Comparison of the two host molecules revealed the impact of steric hindrance in tetramesityl sulfonated tetramethyl resorcarene. Copyright © 2006 John Wiley & Sons, Ltd.
Analysis of androgenic steroid Girard P hydrazones using multistage tandem mass spectrometry
Authors: Kirk Jayne M. , Tarbin Jonathan , Keely Brendan J.
Published: March 2006

Seven androgenic steroids have been converted into steroid hydrazones using Girard P hydrazine and analysed by electrospray ionisation multistage tandem mass spectrometry. The cationic derivatives 17α‐testosterone hydrazone, 17β‐nortestosterone hydrazone, 17β‐bolasterone hydrazone, 17α‐boldenone hydrazone, 17β‐fluoxymesterone hydrazone, 17α‐trenbolone hydrazone and 4‐chloroandrosten‐3,17‐dione hydrazone show good response in positive ion mode with enhancements for the method of up to 33 times relative to the native species. Detailed characterisation of fragmentation pathways reveals structurally specific ions formed by fragmentation of the hydrazine moiety. Comparison of structural similarities among the androgenic steroids allows recognition of common ions/fragmentation processes as well as analyte‐specific transitions. The suitability of the derivatisation approach in the screening of heifer urine for the presence of administered hormones has been demonstrated using partially purified urine spiked with a mixture of androgenic steroids. Copyright © 2006 John Wiley & Sons, Ltd.
Bayesian analysis of latent variable models with non‐ignorable missing outcomes from exponential family
Authors: Song Xin‐Yuan , Lee Sik‐Yum
Published: March 2006

To provide a comprehensive framework for analysing complex non‐normal medical and biological data, we propose a Bayesian approach for a non‐linear latent variable model with covariates, and non‐ignorable missing data, under the exponential family of distributions. The non‐ignorable missing mechanism is defined via a logistic regression model. Based on conjugate prior distributions, full conditional distributions for the implementation of Markov chain Monte Carlo methods in simulating observations from the joint posterior distribution are derived. These observations are used in computing the Bayesian estimates, as well as in implementing a path sampling procedure to evaluate the Bayes factor for model comparison. The proposed methods are illustrated using real data from a study on the non‐adherence of hypertension patients. Copyright © 2006 John Wiley & Sons, Ltd.
Analysis of cluster randomized cross‐over trial data: a comparison of methods
Authors: Turner Rebecca M. , White Ian R. , Croudace Tim
Published: March 2006

In a cluster randomized cross‐over trial, all participating clusters receive both intervention and control treatments consecutively, in separate time periods. Patients recruited by each cluster within the same time period receive the same intervention, and randomization determines order of treatment within a cluster. Such a design has been used on a number of occasions. For analysis of the trial data, the approach of analysing cluster‐level summary measures is appealing on the grounds of simplicity, while hierarchical modelling allows for the correlation of patients within periods within clusters and offers flexibility in the model assumptions. We consider several cluster‐level approaches and hierarchical models and make comparison in terms of empirical precision, coverage, and practical considerations. The motivation for a cluster randomized trial to employ cross‐over of trial arms is particularly strong when the number of clusters available is small, so we examine performance of the methods under small, medium and large (6, 18, 30) numbers of clusters. One hierarchical model and two cluster‐level methods were found to perform consistently well across the designs considered. These three methods are efficient, provide appropriate standard errors and coverage, and continue to perform well when incorporating adjustment for an individual‐level covariate. We conclude that choice between hierarchical models and cluster‐level methods should be influenced by the extent of complexity in the planned analysis. Copyright © 2006 John Wiley & Sons, Ltd.
Comparing two crossing hazard rates by Cox proportional hazards modelling
Authors: Liu Kejian , Qiu Peihua , Sheng Jun
Published: March 2006

Motivated by a clinical trial of zinc nasal spray for the treatment of the common cold, we consider the problem of comparing two crossing hazard rates. A comprehensive review of the existing methods for dealing with the crossing hazard rates problem is provided. A new method, based on modelling the crossing hazard rates, is proposed and implemented under the Cox proportional hazards framework. The main advantage of the proposed method is the utilization of the Box–Cox transformation which covers a wide range of hazard crossing patterns. Simulation studies are conducted for comparing the performance of the existing methods and the proposed one, which show that the proposed method outperforms some of its peers in certain cases. Applications to a kidney dialysis patients data and the zinc nasal spray clinical trial data are discussed. Copyright © 2006 John Wiley & Sons, Ltd.
Polyethylenimine, a cost‐effective transfection reagent
Authors: Ehrhardt Christina , Schmolke Mirco , Matzke Andreas , Knoblauch Alexander , Will Carola , Wixler Viktor , Ludwig Stephan
Published: March 2006

In search for a cheap and effective transfection reagent we used the positively charged polyplex‐forming compound polyethylenimine (PEI). This compound is commercially available from different companies either as a non‐modified chemical reagent or with additives as a more cost intensive transfection reagent. Here we used the non‐modified PEI reagent to optimize transfection protocols for different cell‐lines. With these optimized conditions we were able to transiently transfect a number of cell‐lines up to 40–90%.
Interactions of synaptojanin
Authors: Rosivatz Erika
Published: March 2006

Synaptojanin is a phosphoinositide phosphatase that plays a crucial role in synaptic vesicle recycling. The focus of this review is on the major direct interacting partners of synaptojanin with respect to recognition motifs in synaptojanin isoforms and splice variants. Those proteins that bind synaptojanin are mainly involved in endocytosis and function at the interface between actin and the endocytic machinery. Some interaction partners underline synaptojanin's emerging role in signaling and pathophysiological processes.
Competition and cooperation: Signal transduction by CD28 and CTLA‐4
Authors: Hoff Holger , Burmester Gerd‐R. , Brunner‐Weinzierl Monika C.
Published: March 2006

The closely related members of the Ig‐family of co‐stimulators CD28 and CTLA‐4 (CD152) show distinct functions regarding T cell activation but have also many features in common during T cell differentiation. Although CD28 and CTLA‐4 share some of their intracellular binding partners, CD28 is the main activating co‐stimulator of T cells while the role of CTLA‐4 is to mainly down regulate T cell responses. Despite the well known function of CTLA‐4 as a negative regulator of T cell function, new data suggest that CTLA‐4 is also able to transmit positive signals for increased survival and might be involved in the generation of the memory compartment. The knowledge of how both molecules transmit their respective signals and how these signals are integrated during a T cell response is of importance for the understanding of T cell mediated immune responses and future therapeutic interventions in immune pathologies.
Continuous convergence of relations – a principle in discretization procedures –
Authors: Ansorge R.
Published: March 2006

There are situations in Numerical Analysis concerning the convergence and properties of discretization procedures which seem to be of different type (e.g. convergence to genuine or to weak solutions, convergence to entropy solutions, creation of dicrete solutions which have to imitate properties of the seeked solutions known in advance etc.) but can uniformly be descibed by a property introduced here, called continuous convergence of relations. Historical examples demonstrate this standardization.
Heterogeneity ratio: a measure of beta‐diversity and its use in community classification
Authors: Kobayashi Shiro
Published: March 2006

Fifteen previously proposed similarity indices are examined for the effects of sample size and/or group size (the number of samples included in a cluster). The three indices of Cλ, NESS, and C′λ are free from effects, but the former two are unsuitable for arithmetic averaging unless all of the sample sizes are equal. Thus clustering using C′λ is found to be superior to the combination of any other similarity index and the group‐average strategy. Unfortunately none of these measures have the desirable property of measuring the difference in component species among samples independent of the alpha‐diversity. A new index of similarity (HR) is developed based on the assumption that community from which samples are taken is described by a logseries distribution. This new index measures the beta‐diversity among samples without the influence of sample size and group size, and has the advantage that the significance of fusing samples can statistically be tested. An example clustering with HR is shown and compared with those obtained by other clustering strategies.
Nitrification and nitrogen accumulation in the early stages of primary succession on Mt. Fuji
Authors: Tateno Masaki , Hirose Tadaki
Published: March 2006

The relationship between nitrification potential and nitrogen accumulation was studied in an early successional sere on Mt. Fuji. Soil organic nitrogen accumulated with the invasion of Polygonum cuspidatum and successively with Miscanthus oligostachyus and other species. Laboratory incubation experiments showed a higher nitrification potential at the M. oligostachyus state. The numbers of nitrifying bacteria increased with the progress of succession. No significant difference in nitrate reductase activity was found between pioneer and succeeding species. The soil solution at the M. oligostachyus stage contained a lower level of nitrate than rainwater, while that of the bare ground and the P. cuspidatum stage contained a higher nitrate level than rainwater. It was concluded that the high nitrate levels in the soil solution of the bare ground and the P. cuspidatum stage were due to lower nitrate‐absorbing activity, leading to loss of nitrogen with precipitation, while the lower nitrate levels at the M. oligostachyus stage when higher nitrification activity occurred were due to higher nitrate‐absorbing activity, preventing net loss of nitrogen from the ecosystem.
Seasonal changes in abundance and spatial distribution of the soil arthropods in a Japanese cedar (Cryptomeria japonica D.Don) plantation, with special reference to collembola and acarina
Authors: Hijii Naoki
Published: March 2006

Seasonal changes in abundance and distribution pattern of soil micro‐arthropods were studied in connection with a few environmental factors in a Japanese cedar (Cryptomeria japonicaD. Don) plantation. The soil arthropods were sampled from three different depths at intervals of two months for two years. Of the collected animals (total 51000–155000 m−2), Collembola (20000–76000 m−2), oribatid mites (19000–55000 m−2) and carnivorous mites (6200–21000 m−2) were the numerically dominant animal groups. Low seasonal variations in abundance indicated their seasonal stability in population levels. The trends in seasonal fluctuation were similar among these groups and between the two years, showing bimodal pattern with little peaks in early summer and winter. The pattern of seasonal fluctuation in abundance of carnivorous mites (Pd) was significantly synchronized with that in the total abundance of Collembola and oribatid mites (Pτ). Thus, the number‐ratios (Pd/Pτ) were fairly constant, ranging from 0.10 to 0.25. Seasonal changes in vertical distribution of the three animal groups showed a similar pattern for both years. The downward migrations were shown to be more affected by low temperatures in winter accompanied by snow coverage rather than by the desiccation of the surface soil in summer. All the three groups demonstrated as a whole slightly aggregated patterns of horizontal distribution throughout the two years. Temporal increases in the patchiness indices were observed from summer to autumn when the moisture content of the surface soil was low.
Egg size of skippers (Lepidoptera: Hesperiidae) in relation to their host specificity and to leaf toughness of host plants
Authors: Nakasuji Fusao
Published: March 2006

The adaptive significance of egg size of skippers (Lepidoptera; Hesperiidae) in Japan was evaluated in relation to the leaf toughness of their major host grasses. The hesperids that fed on tougher grasses laid larger eggs. Hesperids that laid larger eggs were larger in body size, but lower in fecundity. They also had a wider host range. Thus, despite the lower fecundity, hesperids may benefit from large eggs by having a wider host range of larvae. Grass feeders had wider range of host plants than broadleaf feeders.
Synchronization of reproductive period among the two male forms and female of the damselfly Mnais pruinosa selys (Zygoptera: Calopterygidae)
Authors: Nomakuchi Shintaro , Higashi Kazunori , Maeda Makoto
Published: March 2006

Ecological parameters in a population of Mnais pruinosa were investigated in a mountain stream. In the study area, there were two forms of male with regard to wing color, the orange‐winged male (esakii) and the hyaline‐winged male (strigata), and only one female form with hyaline wings. Emergence of adults began in late April, and the flying season ended in late June. The time after emergence was spent in maturation, and the insects began to mate when they reached maturity. Longevity of adults was 17.6 days for esakii males, 18.4 days for strigata males and 21.9 days for females. There was little difference in emergence time, maturation period, survivorship curve and longevity among the two male forms and female. In other words, the period for reproductive activities was perfectly coincident among them. The factors influencing the synchronization of emergence were discussed.
Structure of primary Japanese beech (Fagus japonica maxim.) forests in the Chichibu Mountains, central Japan, with special reference to regeneration processes
Authors: Ohkubo Tasuhiro , Kaji Mikio , Hamaya Toshio
Published: March 2006

The floristic composition, structure and dynamics of three primary Fagus japonica stands were investigated in the Chichibu Mountains. F. japonica was dominant [RD(%): 64.9–87.0] and showed a slightly inverse J‐shaped DBH class distribution in the quadrats [No. of canopy stems (H>20m): 87–138/ha]. The stems of F. japonica for each size were distributed in the form of colonies, being scattered almost uniformly, and arranged in positive association with each other. Detailed examination of the bases of the stem groups forming colonies revealed that most of them originated from the bases of dead mother stems and that they were from common stools [No. of large stems (H>10 m) per stool: 6–11]. Among six major canopy gaps observed, only one included stems sprouting from the outer part of F. japonica stools, while all the others were occupied by individuals of species other than F. japonica. After tree‐fall, several undercanopy F. japonica stems remained. Thus canopy gaps in these forest stands recovered through the sprouting of remaining F. japonica stools or by new sprouting of F. japonica individuals adjacent to the gaps. However, it was considered difficult to fill canopy gaps only with sprouts when the distance between the center of a gap and that of a stool surpasses the crown vector. Such places that are not fully occupied by sprouts will be filled by individuals of other canopy and/or under‐canopy species.
A fitness function for optimal life history in relation to density effects, competition, predation and stability of the environment
Authors: Satou Shintarou
Published: March 2006

A fitness function (function maximized under natural selection) is studied in a population model in which the growth of a population is suppressed by crowding, density‐independent continuous mortality (by euryphagous predators) and periodic disturbances. The dynamics of the population density between occurrence of disturbance can be expressed as, dN/dt=(F(N/K)−D)N, where N is the population density, K is the carrying capacity, D is the density‐independent continuous mortality, and F is the growth regulation factor described as a function of crowding (N/K). The period of disturbance is S. The survival rate under disturbance is u. It is concluded that the fitness function is (approximately) a product of competitive ability (C), carrying capacity, and degree of saturation, and is given by CKF−1(D−(lnu)/S). The degree of saturation is the inverse function of regulation factor (F) at the death rate due to predators and disturbance.

I assume a population in which density is regulated only through survival. In this case, a low survival rate at the critical age‐group means a high value of CKF−1(D−(lnu)/S). Therefore, the reciprocal of the density‐dependent survival rate at critical age‐group is a measure of the fitness function. Using this measure, I predict the optimal age (body size) at first reproduction of a species of salamander. I also found that fitness calculated from observed values of l(x) and m(x) includes a tautology.

When the concept of fitness function is compared with the ESS method, the latter is more flexible. However, there is a possibility that an ESS is at the minimum of fitness function.
Dispersal ecology of the maritime plants in the Ryukyu Islands, Japan
Authors: Nakanishi Hiroki
Published: March 2006

The dispersal ecology of seventeen maritime species, which are dominant and/or characteristic species of coastal communities on the Ryukyu Islands, was studied. The species were Calophyllum inophyllum, Canavalia maritima, Clerodendron inerme, Guettarda speciosa, Hernandia sonora, Hibiscus tiliaceus, Ipomoea gracilis, I. pes‐caprae, Messerschmidia argentea, Pandanus odoratissimus, Pongamia pinnata, Scaevola frutescens, Sophora tomentosa, Terminalia catappa, Thespesia populnea, Vigna marina and Wedelia biflora. The structure and size of disseminules and their buoyancy and viability in seawater were examined in the laboratory. The disseminules of these seventeen species have morphological characteristics for buoyancy, and tests showed that these species could be dispersed by sea currents. Drift disseminules on the drift line, seedlings on the hightide line, and young plants of woody species in the herb zone were observed, being abundant on the coasts of the Ryukyu Islands. The Kuroshio Current carries these disseminules from islands where these species form part of the tropical coastal vegetation.
Role of bottom sediments in sustaining plankton production in a Lake ecosystem — Experimental demonstration using enclosed water bodies in a shallow eutrophic Lake
Authors: Sakamoto Mitsuru , Hayashi Hidetake , Otsuki Akira , Aoyama Kanji , Watanabe Yasunori , Hanazato Takayuki , Iwakuma Toshio , Yasuno Masayuki
Published: March 2006

Using large enclosures set in Lake Suwa, experimental studies were conducted to examine the effects of bottom sediments on plankton production in a natural lake ecosystem. Successive changes in biotic and abiotic components in two types of enclosure with and without bottom sediments were surveyed throughout a one‐month period in the early fall of 1985. Remarkable differences were found between the two types of enclosure with regard to the time courses of abundance of chlorophyll, PON, PP, TN, TP and zooplankton as well as those of POC/PON and POC/Chl ratios and primary production rate in terms of mg N m−2 day−1. Quantitative examination of the major causes of these differences revealed that the release of nitrogen and phosphorus from the bottom sediments was significantly effective for sustaining the active production of phytoplankton cells with a high nitrogen and phosphorus content, subsequently resulting in active zooplankton growth.
Sexual difference of lifetime movement in adults of the Japanese skimmer, Orthetrum japonicum (Odonata: Libellulidae), in a forest‐paddy field complex
Authors: Watanabe Mamoru , Higashi Takayoshi
Published: March 2006

The mark‐and‐recapture method was used to study the lifetime movement of the Japanese skimmer, Orthetrum japonicum, in a forest‐paddy field complex in the warmtemperate zone of Japan. The flight season was from mid April to late June. The age structure showed that the maiden flight occurred towards the forest from the emergence sites (paddy fields) for both sexes. The insects returned to the paddy fields after maturation. The total number of skimmers estimated in the whole survey area was about 1000–2000, of which about 200 males were found in the paddy fields. The average lengths of the immature and reproductive periods were about 10 and 20 days in both sexes, respectively. Most mature males tended to stay in the paddy fields and showed territorial behavior, while most mature females moved frequently between the forest and the paddy fields. The average extent of each territory was about 19 m2, being established mainly in the shady paddy fields. Few males were sneakers. The available habitat throughout the life span for the skimmers was both the paddy fields and the forest.
A Markov approach for describing post‐fire succession of vegetation
Authors: Isagi Yuji , Nakagoshi Nobukazu
Published: March 2006

Vegetation dynamics in the coastal area of the Seto Inland Sea region in Japan, where wild fires occur frequently, were described using a stationary Markov model. In this region, vegetation types of Miscanthus‐Pleioblastus grassland, Lespedeza‐Mallotus scrub, Pinus‐Rhododendron forest and Crassocephalum‐Erechtites community have been identified, and these show cyclic succession under the influence of fires.

The model uses parameters determining fire frequency and rate of successional change to analyze the effect of variation in these parameters on the areal ratio of each vegetation type at equilibrium and on the time taken for one vegetation type to succeed another (elapsed successional time). The effect of fire frequency differs between hypothetical habitats with high and low productivity. A policy for vegetation management in areas of high and low productivity is proposed. The advantages and limitations of applying Markov models to studies of vegetation succession are also discussed.
Summer dietary compositions of sika deer on Yakushima Island, southern Japan
Authors: Takatsuki Seiki
Published: March 2006

Summer food habits of Sika deer (Cervus nippon yakushimae) on Yakushima Island, southern Japan, were studied focusing in particular on Pseudosasa owatarii, a dwarf bamboo native to the island. Fecal analyses showed that the food habit of the Sika deer on Yakushima island was plastic: the dietary composition was dominated by graminoids (ca. 90%), particularly P. owatarii (50%–60%) in the bamboo grassland of the P. owatarii zone above the timber line, whereas leaves and non‐leafy parts of woody plants were important in the crytomeria forest and evergreen broad‐leaved forest below the timber line. The maximum culm age of P. owatarii was 8.5 yr, but the majority of leaves (97.8%) were younger than 2.5 yr. Since the weight contribution of the leaves is great (27.7%) and the turnover rate is high, the P. owatarii grassland affords a good foraging place for the Sika deer on Yakushima Island.
Role of rhizomes in tussock formation by Carex thunbergii var. Appendiculata
Authors: Nishikawa Yoko
Published: March 2006

Several types of tussock formed by Carex thunbergii var. appendiculata were compared with respect to the growth pattern of their rhizomes at various developmental stages at Benten Marsh in Yufutsu Mire, Hokkaido, Japan. The rhizomes were classified into three types based on their function: 1, very short rhizomes; 2, intermediate‐length rhizomes which grow upwards to raise the shoot base; 3, long rhizomes which grow horizontaly to spread the plant. The extent of development of the tussock and the total length of rhizomes per shoot was inversely related with the number of Type 3 rhizomes, and positively related with Types 1 and 2 rhizomes. The tussock was made of dead roots, dead rhizomes and much litter, which provided a substitute for soil for the rhizomes and absorbing roots. The growth conditions of the Carex changed from aerobic and eutrophic to anoxic and oligotrophic with tussock development. It is concluded that the tussock is adaptive to anoxic conditions.
Germination ecology of coastal plants in relation to salt environment
Authors: Mariko Shigeru , Kachi Naoki , Ishikawa Shin‐ichi , Furukawa Akio
Published: March 2006

Responses of seed germination to salinity were examined using 37 species collected from salt marshes, cliffs, and fore (unstable) and hind (stable) sand dunes along Japanese coasts. For comparison, seed germination of nine inland species was also examined. The soil salinities in salt marshes ranged from 150 to 300 mmol/L NaCl, whereas those in fore and hind dunes ranged from 0 to 150 mmol/L NaCl, with a few exceptions. Cliff soils showed relatively high salinities up to 300 mmol/L NaCl. Ciff and foredune soils that encountered a typhoon and storm showed high salinities >300 mmol/L NaCl. Salt tolerance in seed germination of coastal plants was ordered by comparing the responses of percentage and rate of germination to salinity conditions up to 200 mmol/L NaCl, being in the order of salt marsh>cliff>foredune≅hind dune≅inland. Thse results indicate that salt tolerance in seed germination of coastal plants is closely related to the salinity conditions of their habitats. Germination experiments under favorable conditions showed that a high percentage of the seeds of salt marsh species germinate rapidly, those of diff species germinate slowly and those of foredune species exhibit a low percentage and low rate of germination. It seems that these germination characteristics contribute to the success of germination at the ‘safe site’ and the subsequent survivorship of emerged plants in their natural habitats.
Canopy photosynthetic production in a Japanese larch stand. I. Seasonal and vertical changes of leaf characteristics along the light gradient in a canopy
Authors: Kurachi Nahoko , Hagihara Akio , Hozumi Kazuo
Published: March 2006

In an 18 year old Japanese larch stand, leaf characteristics such as area, weight, gross photosynthetic rate and respiration rate were studied in order to obtain basic information on estimating canopy photosynthesis and respiration. The leaf growth courses in area and weight from bud opening were approximated by simple logistic curves. The growth coefficient for the area growth curve was 0.155–0.175 day−1, while that for the weight growth was 0.112–0.117 day−1. The larger growth coefficient in area growth caused the seasonal change in specific leaf area (SLA) that increased after bud opening to its peak early in May at almost 300 cm2 g−1 and then decreased until it leveled off at about 140 cm2g−1. The change in SLA indicates the possibility that leaf area growth precedes leaf thickness growth. The relationship between the coefficients a and b of the gross photosynthetic rate (p)‐light flux density (1) curve (p=bI/(1+aI)) and the mean relative light flux density (I′/I0) at each canopy height were approximated by hyperbolic formulae:a=A/(I′/I0)+B and b=C/(I′/I0)+D. Leaf respiration rate was also increased with increasing I′/I0. Seasonal change of gross photosynthetic rate and leaf respiration rate were related to mean air temperature through linear regression on semilogarithmic co‐ordinates.