bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetohydrodynamic-calibrated edge-localized mode model in simulations of International Thermonuclear Experimental Reactor
Authors: Onjun Thawatchai , Kritz Arnold H. , Bateman Glenn , Parail Vassili
Published: August 2005

Self-consistent simulations of the International Thermonuclear Experimental Reactor (ITER) [R. Aymar, P. Barabaschi, and Y. Shimomura, Plasma Phys. Controlled Fusion 44, 519 (2002)] have been carried out using the JETTO-integrated modeling code in which theory-motivated models are used for the H-mode pedestal and for the stability conditions that lead to the edge-localized mode (ELM) crashes. Transport is described by combining the anomalous mixed Bohm/gyro-Bohm model [M. Erba, A. Cherubini, V. V. Parail, and A. Taroni, Plasma Phys. Controlled Fusion 39, 261 (1997)] with the NCLASS neoclassical transport model [W. A. Houlberg, K. C. Shaing, S. P. Hirshman, and M. C. Zarnstorff, Phys. Plasmas 4, 3231 (1997)] in the core region, while only neoclassical transport is used in the pedestal region. In the simulations, an ELM crash can be triggered either by a pressure-driven ballooning mode or by a current-driven peeling mode, depending on which instability reaches its stability criterion first. The equilibrium and magnetohydrodynamics (MHD) stability analyses codes, HELENA and MISHKA [A. B. Mikhailovskii, G. T. A. Huysmans, S. E. Sharapov, and W. Kerner, Plasma Phys. Rep. 23, 713 (1997)], are used to evaluate the edge stability of the plasma just prior to an ELM crash in order to calibrate and confirm the validity of the stability criteria used to trigger ELMs in the JETTO simulations. It is found that the simulation of the ITER baseline case yields a fusion Q of 16.6, with the electron and ion temperatures at the top of the pedestal of 4.4 and 4.9keV, respectively. The high values of the pedestal temperature result from access to the second stability region of the ballooning mode. Simulation sensitivity studies are carried out by varying parameters such as the auxiliary heating power and the width of the pedestal. When the auxiliary heating power is turned off, it is found that significant fusion power is sustained and that access to ballooning mode second stability is maintained.
Observation of the self-generated toroidal magnetic field in rotamak
Authors: Petrov Yuri , Zhong Fangchuan , Huang Tian-Sen
Published: August 2005

An experimental study of the self-generated toroidal magnetic field in rotamak field-reversed configuration plasmas is performed in the case of high input power (200kW), long-duration (40ms) discharges. In one round of experiments, the polarity of the toroidal field in the poloidal cross section is different not only from one hemisphere to another but also in radial direction. In another round of experiments, the toroidal field is seen to reverse its sign in the course of a shot. The data for the field are fitted with the vector spherical harmonic functions. The poloidally swirling currents associated with the self-generated toroidal field are shown to contribute to the formation of the two-peak structure of the toroidal plasma current.
Enhanced self-magnetic field by atomic polarization in partially stripped plasma produced by a short and intense laser pulse
Authors: Hu Qiang-Lin , Liu Shi-Bing , Jiang Y. J. , Zhang Jie
Published: August 2005

The enhancement and redistribution of a self-generated quasistatic magnetic field, due to the presence of the polarization field induced by partially ionized atoms, are analytically revealed when a linearly polarized intense and short pulse laser propagates in a partially stripped plasma with higher density. In particular, the shorter wavelength of the laser pulse can evidently intensify the amplitude of the magnetic field. These enhancement and redistribution of the magnetic field are considered physically as a result of the competition of the electrostatic field (electron-ion separation) associated with the plasma wave, the atomic polarization field, and the pondoromotive potential associated with the laser field. This competition leads to the generation of a positive, large amplitude magnetic field in the zone of the pulse center, which forms a significant difference in partially and fully stripped plasmas. The numerical result shows further that the magnetic field is resonantly modulated by the plasma wave when the pulse length is the integer times the plasma wavelength. This apparently implies that the further enhancement and restructure of the large amplitude self-magnetic field can evidently impede the acceleration and stable transfer of the hot-electron beam.
Hydrogen analysis in solid samples using laser-induced helium plasma at atmospheric pressure
Authors: Pardede Marincan , Kurniawan Koo Hendrik , Lie Tjung Jie , Hedwig Rinda , Idris Nasrullah , Kobayashi Takao , Maruyama Tadashi , Lee Yong Inn , Kagawa Kiichiro , Tjia May On
Published: August 2005

A special technique for the modification of laser-induced breakdown spectroscopy (LIBS) has been developed to improve the spectral quality of hydrogen emission from a solid sample in helium gas at atmospheric pressure. In this technique, the plasma was generated by focusing a fundamental Nd-YAG (yttrium aluminum garnet) laser into a surrounding helium gas. The helium atoms excited to their metastable states would then serve to excite the atoms of the solid material vaporized by using another Nd-YAG laser. When properly synchronized, the resulting hydrogen emission line of H I 656.2 nm shows a dramatic improvement of the emission intensity and the spectral quality over what was obtained by conventional LIBS technique. This study further reveals that this improvement is mainly due to the role of the metastable excited state in a helium atom, which allows the delayed detection to be performed at a favorable moment when the charged particles responsible for the strong Stark broadening effect in the plasma have mostly disappeared.
Diffraction measurement and analysis of slanted holographic polymer dispersed liquid crystal
Authors: Sun Xiao Hong , Tao Xiao Ming , Ye Ting Jin , Szeto Yau-Shan , Cheng Xiao Yin
Published: August 2005

In this article, slanted holographic polymer dispersed liquid-crystal films are prepared by using a single-prism interferometer. Their diffraction characteristics are measured at various incident angles. Based on the coupled-wave theory of diffraction efficiency and incident angles, the grating period, film thickness, and slanted angle of the volume grating are derived. A good agreement is demonstrated between the experimental and theoretical results, and supported by scanning electron microscopy observation. The electrical switching behavior of the grating is also described. The diffraction efficiency changes from 65% to a stable value of 10% at an electric field of 33V∕μm. On the other hand, based on the theoretical prediction of diffraction efficiency, the optimum film thickness and Bragg grating period are determined, which sheds light on the implementation of our experiments.
Electromechanical responses of single-walled carbon nanotubes: Interplay between the strain-induced energy-gap opening and the pinning of the Fermi level
Authors: Guo G. Y. , Liu Lei , Chu K. C. , Jayanthi C. S. , Wu S. Y.
Published: August 2005

A comprehensive picture of electromechanical responses of carbon single-walled nanotubes (SWNTs) is obtained using ab initio density-functional theory and self-consistent π-orbital Hamiltonian. We find a linear behavior of the energy gap of zigzag SWNTs as a function of the axial strain with different slopes for compression versus extension. Observed small changes in conductance even with a substantial energy gap due to the strain is attributed to the pinning of the Fermi level near the top of the valence band.
Classical and quantum kinetics of the Zakharov system
Authors: Marklund Mattias
Published: August 2005

A kinetic theory for quantum Langmuir waves interacting nonlinearly with quantum ion-acoustic waves is derived. The formulation allows for a statistical analysis of the quantum correction to the Zakharov system. The influence of a background random phase on the modulational instability is given. In the coherent case, the effect of the quantum correction is to reduce the growth rate. Moreover, in the classical limit, a bifurcation develops in the dispersion curves due to the presence of partial coherence. However, the combined effect of partial coherence and a quantum correction may give rise to an increased modulational instability growth rate, as compared to the classical case. The results may be of significance in dense astrophysical plasmas and laboratory laser-plasma systems.
Driven reconnection in a quadrupole cusp field
Authors: Aydemir A. Y.
Published: August 2005

Driven magnetic reconnection in a quadrupole cusp field is examined numerically in various collisionality regimes. Quasi-steady-state reconnection rates far in excess of often-quoted limits are observed. As expected, the rate is determined by external boundary conditions and appears to be limited only by computational concerns; thus, in this configuration the slow reconnection is differentiated from the fast one only by changes in the reconnection-layer geometry. Collisional reconnection exhibits the typical extended current layer of the Sweet-Parker model, whereas the collisionless reconnection mediated by kinetic-Alvén or whistler waves has the Petschek-type “X-layer” configuration. The current density at the X point is reduced in the collisionless cases, in qualitative agreement with the results from the Versatile Toroidal Facility experiment.
Power absorption of high-frequency electromagnetic waves in a partially ionized magnetized plasma
Authors: Guo Bin , Wang Xiaogang
Published: August 2005

Power absorption of high-frequency electromagnetic waves in a uniformly magnetized plasma layer covering a highly conducting surface is studied under atmosphere conditions. It is assumed that the system consists of not only electrons and positive ions but negative ions as well. By a general formula derived in our previous work [B. Guo and X. G. Wang, Plasma Sci. Tech. 7, 2645 (2005)], the total power absorption in the plasma layer with multiple reflections between an air-plasma interface and the conducting surface is computed. The results show that although the existence of negative ions greatly reduces the total power absorption, the magnetization of the plasma can, however, partially enhance it. Parameter dependence of the effects is calculated and discussed.
Light-current characteristics of quantum dots with localized recombination
Authors: Pask H. J. , Summers H. D. , Blood P.
Published: August 2005

We have computed the light-current characteristics of an ensemble of 106 quantum dots with localized Shockley–Read–Hall and radiative recombination between states with integer occupancy. The radiative and nonradiative recombination rates have similar dependences on electron number and, hence, there is no transition from one dominant process to another as the injection is increased. The light-current characteristics of the dot system alone are similar for non-charge-neutral and neutral dots even though the individual recombination rates have very different dependences on electron number. Light emission from the dots as a function of total current shows sublinear behavior due to the wetting layer contribution to the current.
Continuous-wave operation of 1.5μm InGaAs∕InGaAsP∕InP quantum dot lasers at room temperature
Authors: Kim H. D. , Jeong W. G. , Lee J. H. , Yim J. S. , Lee D. , Stevenson R. , Dapkus P. D. , Jang J. W. , Pyun S. H.
Published: August 2005

Continuous-wave operation at room temperature from InGaAs∕InGaAsP∕InP quantum dot (QD) laser diodes (LD) has been achieved. A ridge waveguide QD LD with 7 QD-stacks in the active region lases at 1.503μm at 20°C and that with 5 QD-stacks lases at 1.445μm at room temperature. The shift in lasing wavelength is believed to be due to the difference in the quantized energy states involved in producing gain for lasing. With smaller number of QD stacks and shorter cavity length, the lasing wavelength shifts to shorter wavelength indicating that more of higher excited states are involved in producing gain. By increasing the number of QD stacks to 15, lasing at 1.56μm has been achieved under pulsed mode.
Broadband and gap-free response of a terahertz system based on a poled polymer emitter-sensor pair
Authors: Zheng Xuemei , Sinyukov Alexander , Hayden L. Michael
Published: August 2005

We present a terahertz (THz) system based on a poled electro-optic (EO) polymer emitter-sensor pair for the generation and detection of broadband electromagnetic pulses free of spectral gaps. The gap-free THz spectrum obtained from the system is attributed to the amorphous form of the EO polymer films. Using ∼50-fs laser pulses centered at ∼800nm, a ∼100-μm thick emitter, and a ∼180-μm thick sensor, the observable bandwidth is ∼12THz. We also present an experimental study, in a systematic manner, on the effect of phase mismatch in the polymer emitter-sensor pair.
Low-frequency 1∕f-noise in (La0.7Sr0.3MnO3)0.95:(MgO)0.05 nanocomposite films
Authors: Esseling M. , Moshnyaga V. , Samwer K. , Marx A. , Gross R.
Published: August 2005

The (La0.7Sr0.3MnO3)0.95:(MgO)0.05 nanocomposite system (LSMO:MgO) shows a low-field magnetoresistance up to 30% at low temperatures. The low-frequency 1∕f-noise was investigated extensively to characterize the LSMO∕MgO interface. The noise was found to be independent of both an applied magnetic field and the bias current. Furthermore, the temperature dependence of the noise level shows a maximum which can be connected to the temperature dependence of the resistance. The measured noise level is comparable to epitaxial manganite systems without doped grain boundaries. This suggests that the quality of the coherent LSMO∕MgO interfaces where the low-frequency noise is predominantly generated is very high.
Direct regulation of intestinal fate by Notch
Authors: Stanger Ben Z. , Datar Radhika , Murtaugh L. Charles , Melton Douglas A.
Published: August 2005

The signals that maintain the proper balance between adult intestinal cell types are poorly understood. Loss-of-function studies have implicated the Notch pathway in the regulation of intestinal fate during development. However, it is unknown whether Notch has a role in maintaining the balance of different cell types in the adult intestine and whether it acts reversibly. To determine whether Notch has a direct effect on intestinal development and adult intestinal cell turnover, we have used a gain-of-function approach to activate Notch. Ectopic Notch signaling in adult intestinal progenitor cells leads to a bias against secretory fates, whereas ectopic Notch activation in the embryonic foregut results in reversible defects in villus morphogenesis and loss of the proliferative progenitor compartment. We conclude that Notch regulates adult intestinal development by controlling the balance between secretory and absorptive cell types. In the embryo, Notch activation perturbs morphogenesis, possibly through effects on stem or progenitor cells.
Cell–Matrix Entanglement and Mechanical Anchorage of Fibroblasts in Three-dimensional Collagen Matrices
Authors: Jiang Hongmei , Grinnell Frederick
Published: August 2005

Fibroblast-3D collagen matrix culture provides a physiologically relevant model to study cell–matrix interactions. In tissues, fibroblasts are phagocytic cells, and in culture, they have been shown to ingest both fibronectin and collagen-coated latex particles. Compared with cells on collagen-coated coverslips, phagocytosis of fibronectin-coated beads by fibroblasts in collagen matrices was found to be reduced. This decrease could not be explained by integrin reorganization, tight binding of fibronectin beads to the collagen matrix, or differences in overall bead binding to the cells. Rather, entanglement of cellular dendritic extensions with collagen fibrils seemed to interfere with the ability of the extensions to interact with the beads. Moreover, once these extensions became entangled in the matrix, cells developed an integrin-independent component of adhesion. We suggest that cell–matrix entanglement represents a novel mechanism of cell anchorage that uniquely depends on the three-dimensional character of the matrix.
The C-Terminal Tail of the Polycystin-1 Protein Interacts with the Na,K-ATPase α-Subunit
Authors: Zatti Alessandra , Chauvet Veronique , Rajendran Vanathy , Kimura Thoru , Pagel Phillip , Caplan Michael J.
Published: August 2005

Polycystin-1 (PC-1) is the product of the PKD1 gene, which is mutated in autosomal dominant polycystic kidney disease. We show that the Na,K-ATPase α-subunit interacts in vitro and in vivo with the final 200 amino acids of the polycystin-1 protein, which constitute its cytoplasmic C-terminal tail. Functional studies suggest that this association may play a role in the regulation of the Na,K-ATPase activity. Chinese hamster ovary cells stably expressing the entire PC-1 protein exhibit a dramatic increase in Na,K-ATPase activity, although the kinetic properties of the enzyme remain unchanged. These data indicate that polycystin-1 may contribute to the regulation of Na,K-ATPase activity in kidneys in situ, thus modulating renal tubular fluid and electrolyte transport.
HEALTH INSURANCE COVERAGE AND REEMPLOYMENT OUTCOMES AMONG OLDER DISPLACED WORKERS
Authors: LIN EMILY Y.
Published: August 2005

This article investigates the relationship between health insurance coverage and employment behavior among older workers with an involuntary job loss. It finds that various sources of health insurance are available to mitigate the circumstances where employer‐sponsored health insurance is terminated when older workers lose jobs involuntarily. However, older displaced workers remain less likely to be insured than comparable nondisplaced workers by 7.6 percentage points one year after the job loss. The analysis also reveals that having secure health coverage before job displacement is associated with lower probabilities of reemployment and longer postdisplacement nonemployment spells. (JEL I12, J32, J63, J14)
EDA for HLM: Visualization when Probabilistic Inference Fails
Authors: Bowers Jake , Drake Katherine W.
Published: August 2005

Nearly all hierarchical linear models presented to political science audiences are estimated using maximum likelihood under a repeated sampling interpretation of the results of hypothesis tests. Maximum likelihood estimators have excellent asymptotic properties but less than ideal small sample properties. Multilevel models common in political science have relatively large samples of units like individuals nested within relatively small samples of units like countries. Often these level-2 samples will be so small as to make inference about level-2 effects uninterpretable in the likelihood framework from which they were estimated. When analysts do not have enough data to make a compelling argument for repeated sampling based probabilistic inference, we show how visualization can be a useful way of allowing scientific progress to continue despite lack of fit between research design and asymptotic properties of maximum likelihood estimators.

Somewhere along the line in the teaching of statistics in the social sciences, the importance of good judgment got lost amid the minutiae of null hypothesis testing. It is all right, indeed essential, to argue flexibly and in detail for a particular case when you use statistics. Data analysis should not be pointlessly formal. It should make an interesting claim; it should tell a story that an informed audience will care about, and it should do so by intelligent interpretation of appropriate evidence from empirical measurements or observations.

—Abelson, 1995, p. 2

With neither prior mathematical theory nor intensive prior investigation of the data, throwing half a dozen or more exogenous variables into a regression, probit, or novel maximum-likelihood estimator is pointless. No one knows how they are interrelated, and the high-dimensional parameter space will generate a shimmering pseudo-fit like a bright coat of paint on a boat's rotting hull.

—Achen, 1999, p. 26
p63 deficiency activates a program of cellular senescence and leads to accelerated aging
Authors: Keyes William M. , Wu Ying , Vogel Hannes , Guo Xuecui , Lowe Scott W. , Mills Alea A.
Published: August 2005

The p53 tumor suppressor plays a key role in organismal aging. A cellular mechanism postulated to drive the aging process is cellular senescence, mediated in part by p53. Although senescent cells accumulate in elderly individuals, most studies have relied on correlating in vitro senescence assays with in vivo phenotypes of aging. Here, using two different mouse models in which the p53-related protein p63 is compromised, we demonstrate that cellular senescence and organismal aging are intimately linked and that these processes are mediated by p63 loss. We found that p63+/- mice have a shortened life span and display features of accelerated aging. Both germline and somatically induced p63 deficiency activates widespread cellular senescence with enhanced expression of senescent markers SA-β-gal, PML, and p16INK4a. Using an inducible tissue-specific p63 conditional model, we further show that p63 deficiency induces cellular senescence and causes accelerated aging phenotypes in the adult. Our results thus suggest a causative link between cellular senescence and aging in vivo, and demonstrate that p63 deficiency accelerates this process.
Melanocytic nevi are associated with neurofibromas in neurofibromatosis, type I, but not sporadic neurofibromas. A study of 226 cases*
Authors: Ball Nigel J. , Kho Grace T.
Published: August 2005

Background:  Neurofibromatosis, type 1, is associated with cutaneous melanin pigmentation, but an association with ordinary melanocytic nevi has not been described.

Methods:  This retrospective case‐control study was designed to see if neurofibromas in patients with neurofibromatosis, type 1 (NF‐1) differ from sporadic neurofibromas (SN) in their incidence of associated melanocytic nevi and other histologic features. Slides from 114 NF‐1 were compared with 112 SN and 300 intradermal melanocytic nevi (IDN).

Results:  Small lentiginous melanocytic nevi were identified over 13 NF‐1 (11%) but no SN (P = 0.0002). Compared with other NF‐1, NF‐1 with nevi were more frequently associated with melanocytic hyperplasia, giant melanosomes and diffuse neurofibroma (P < 0.03). Compared with SN, NF‐1 were also more frequently associated with melanocytic hyperplasia, lentigo simplex‐like changes, diffuse neurofibroma and plexiform neurofibroma (P < 0.001). Sebaceous hyperplasia (14%), dermal elastosis (9%), lipomatous change (8%), epithelial cysts (4%) and keratin granulomas or folliculitis (3%) were not significantly different in prevalence between NF‐1, SN and the control group of IDN.

Conclusions:  This study suggests that there is a difference in the potential for melanocytic proliferation in NF‐1 compared with SN. NF‐1, SN and IDN are associated with a similar range of incidental histologic changes.
‘Specific’ cutaneous infiltrate of B‐cell chronic lymphocytic leukemia at the site of a florid herpes simplex infection
Authors: Ziemer Mirjana , Bornkessel Anja , Hahnfeld Sabine , Weyers Wolfgang
Published: August 2005

Background:  Specific cutaneous infiltrates in patients with leukemia generally carry a grim prognosis. However, non‐neoplastic skin diseases may be associated with recruitment of normal and neoplastic leukocytes circulating in the peripheral blood. In those instances, neoplastic cells may be detected in skin lesions without an adverse effect on prognosis.

Methods:  In a patient with B‐cell chronic lymphocytic leukemia, a specific infiltrate developed at the site of a florid herpes simplex infection. Clinically, the lesion presented itself as an ulcerated tumor.

Results:  Histopathologically, the lesion was characterized by a dense, diffuse infiltrate of small hyperchromatic lymphocytes throughout the entire dermis. Lymphocytes showed an aberrant CD20+/CD43+/CD5+ phenotype of neoplastic B cells, and monoclonal rearrangement of immunoglobulin gamma genes could be demonstrated by polymerase chain reaction. Although criteria for leukemia cutis were fulfilled, the patient did well.

Conclusions:  The cutaneous infiltrate of neoplastic cells seemed to be part of a physiologic response to the antigenic stimulus, rather than indicating an exacerbation of leukemia.
The diagnostic concordance of actinic keratosis and squamous cell carcinoma
Authors: Davis Daniel A. , Donahue John P. , Bost James E. , Horn Thomas D.
Published: August 2005

Abstract:  Diagnostic concordance of intraepithelial malignancy is generally only fair. Because the diagnosis of actinic keratosis (AK) and squamous cell carcinoma (SCC) is not uniform and because such terms are not consonant with the nomenclature of other human epithelial malignancies, nomenclature revisions have been attempted. One hundred dermatopathologists were solicited to review 15 tissue sections representing a spectrum of varying thickness epidermal malignancy and to choose either AK or SCC as the diagnosis. Among the 77 participating dermatopathologists, intraclass correlation was high for what was perceived as AK, SCC, and their differentiation. Development of a two‐tiered diagnostic system that retains our present diagnostic capabilities, but better fits the pathobiology of superficial epidermal malignancy is suggested.
Skin metastases from unknown origin: role of immunohistochemistry in the evaluation of cutaneous metastases of carcinoma of unknown origin
Authors: Azoulay Sandy , Adem Camilo , Pelletier François LE. , Barete Stéphane , Francès Camille , Capron Frédérique
Published: August 2005

Abstract:  Determining the primary origin of skin metastases might be a challenging issue for pathologists, especially when there is no primary history or when this history is unavailable. The poor specificity of morphological appreciation is challenging, emphasizing the need for ancillary studies. We have retrieved 44 cases of skin metastases from our pathology files. Paraffin blocks were collected and homemade tissue arrays were made. We have tried to assess the primary origin based on morphological data alone, and then using 13 antibodies (cytokeratins (CK) 5/6, 7, 19, 20, thyroid transcription factor‐1, carcinoembryonic antigen, PS100, tumor‐associated glycoprotein 72, BerEP4, estrogen receptor (ER), progesterone receptor (PR), CD10, and E‐cadherin). Most metastases in our series were from breast (13) and colorectal cancers (six) as they are the main clinical activity in our hospital. Only 44% of cases were correctly assessed based on the sole morphology, emphasizing the need for ancillary studies. CK 20, ER, and PR were the most helpful markers to determine the primary origin of skin metastases by highlighting colorectal origin and mammary origin, respectively. By far, clinical information and morphological evaluation are more reliable than the use of ancillary techniques, which have to be used in the absence of the former one and the poor differentiation of the latter ones.
From Foraging To Farming: Explaining The Neolithic Revolution
Authors: Weisdorf Jacob L.
Published: August 2005

Abstract.  This article reviews the main theories about the prehistoric shift from hunting and gathering to agriculture. The transition, also known as the Neolithic Revolution, was ultimately necessary to the rise of modern civilization by creating the foundation for the later process of industrialization and sustained economic growth. The article provides a brief historical survey of the leading hypotheses concerning the rise of agriculture proposed in the archaeological and anthropological literature. It then turns to a more detailed review of the theories put forth in the economic literature.
Research And Development Productivity And Spillovers: Empirical Evidence At The Firm Level
Authors: Wieser Robert
Published: August 2005

Abstract. A variety of methods have been used to investigate the empirical relationship between research and development (R&D) spending and the productivity of firms. The most widely employed frameworks are the production function and the associated productivity framework. In these settings, productivity growth is related to expenditures on R&D, and an attempt is made to estimate statistically the part of productivity growth that can be attributed to R&D activities. This article surveys the expansive body of empirical literature on this subject and finds a large and significant impact of R&D on firm performance on average. However, the estimated returns vary considerably between the different studies due to differences across data samples and econometric models, as well as methodological and conceptual issues. A meta‐analysis on the studies surveyed reveals that the estimated rates of return do not significantly differ between countries, whereas the estimated elasticities do. Furthermore, the estimated elasticities are significantly higher in the 1980s and consistently higher in the 1990s compared with the 1970s. Hence, contrary to a widely held belief, we find no convincing evidence of an exhaustion of R&D opportunities in the last two decades.
Differentiation of Salmonella Gallinarum biovar Gallinarum from Salmonella Gallinarum biovar Pullorum by PCR‐RFLP of the fimH gene
Authors: Kisiela D. , Kuczkowski M. , Kiczak L. , Wieliczko A. , Ugorski M.
Published: August 2005

In our studies on FimH adhesins expressed by different Salmonella serovars, we cloned and sequenced the fimH genes from Salmonella enterica ssp. Enterica ser. Gallinarum biovar Gallinarum and S. enterica ssp. Enterica ser. Gallinarum biovar Pullorum. Comparison of the nucleotide sequences revealed the presence of a single‐nucleotide polymorphism (SNP) at position 544 bp from the A of the start codon of the fimH open reading frame (ORF). Further analysis of the restriction enzyme sites in fimH gene showed that the SNP at this position is responsible for a sequence specifically recognized by SacI in S. Gallinarum biovar Gallinarum only, making it possible to differentiate both biovars with the use of polymerase chain reaction‐restriction fragment length polymorphism (PCR‐RFLP). Digestion of PCR amplicons of the fimH gene from S. Gallinarum biovar Gallinarum strains with SacI gave two DNA fragments of 554 and 472 bp and only one fragment of 1026 bp for S. Gallinarum biovar Pullorum. This allows a clear differentiation between these two biovars.
Trials to Induce Protective Immunity in Mice and Sheep by Application of Protoscolex and Hydatid Fluid Antigen or Whole Body Antigen of Echinococcus granulosus
Authors: Hashemitabar G. R. , Razmi G. R. , Naghibi A.
Published: August 2005

In the current study, soluble proteins prepared from 200 mature Echinococcus granulosus and protoscolices of sheep hydatid cysts were applied to immunize sheep and mice respectively. The samples were mechanically homogenized in a blender, sonicated and the final yield was maintained at −20°C until analysis. Hydatid fluid was isolated from liver or lung of sheep under sterile conditions. In the first experiment, 15 mice were randomly allocated to three groups of five mice each. Each mouse in groups 1 and 2 was immunized with 100 μg of hydatid fluid and protoscolex proteins in 100 μl of phosphate‐buffered saline (PBS) and emulsified with an equal volume of Freund's complete adjuvant (FCA) respectively. The mice of group 3 were immunized with adjuvant in PBS. The mice were boosted 4 weeks after the first vaccination with the same preparation except that FCA was replaced by Freund's incomplete adjuvant (FIA). In the second experiment, eight male or female lambs 4–6 months of age, were allocated to two groups of four lambs each. Each lamb in the test group was vaccinated subcutaneously in the neck with a 2‐ml dose of vaccine (1 mg of whole body protein of E. granulosus dissolved in 1 ml of PBS plus 1 ml of FCA). Control lambs were vaccinated with adjuvant in PBS. Lambs were boosted the same way as in the first experiment. Three weeks after the second vaccination, each mouse and lamb received a challenge infection with 2000 protoscolices intraperitoneally and each lamb additionally received 10 gravid E. granulosus. All mice and sheep were killed after 7 months and examined for hydatid cysts. In these studies, protective immunity was induced in mice with protoscolex protein and with hydatid fluid, and in sheep with whole‐body homogenate of E. granulosus and the levels of protection afforded were found to be 72.1, 82.6 and 90.9% respectively.
Serological Evidence ofEhrlichiaspp. Exposure in Cats from Northeastern Spain
Authors: Ortuño A. , Gauss C. B. L. , García F. , Gutierrez J. F.
Published: August 2005

There is little information aboutEhrlichia canisas an infectious agent in cats. In order to estimate the prevalence of antibodies toE. canisin the feline population, 235 cat sera were analysed by indirect fluorescent‐antibody test. With the objective to determine some risk factors associated with seropositivity, serum samples were divided into two groups: urban stray cats and pet cats. The seroprevalence detected was 17.9%. Most positive sera (83.3%) showed low antibody titres (<1:80). Seropositivity was very similar when comparing the two groups of animals: 17.4% in urban stray cats and 18.4% in pet cats. Results revealed that cats are exposed toEhrlichiaspp. infection, as the low antibody titres detected and the serological cross‐reactivity betweenEhrlichiaspecies do not allow us to confirmE. canisexposure.
Genetic Characterization of a Caprine Pestivirus as the First Member of a Putative Novel Pestivirus Subgroup
Authors: De Mia G. M. , Greiser‐Wilke I. , Feliziani F. , Giammarioli M. , De Giuseppe A.
Published: August 2005

Currently, the genus Pestivirus comprises four approved species, namely bovine viral diarrhoea viruses 1 and 2 (BVDV‐1, BVDV‐2), classical swine fever virus and border disease virus (BDV). Recently, three major genotypes have been identified within the species BDV and termed as subgroups BDV‐1, BDV‐2 and BDV‐3. Here, an isolate from animals in a herd showing BD‐like syndromes, which occurred in central Italy was analysed. A reverse transcriptase polymerase chain reaction was performed using primers that specifically amplify a fragment of the 5′‐non‐coding region (5′‐NCR) from BDV. Both the 5′‐NCR fragment and the entire Npro gene were sequenced and used for genetic typing. The 5′‐NCR sequence revealed that the newly isolated Pestivirus could be allocated to the BDV species. Interestingly, the Npro sequence of this virus isolate significantly differed from all the ovine pestiviruses previously described, providing evidence for the presence of an additional subgroup within the species BDV.
A National Surveillance of Shiga Toxin‐Producing Escherichia coli in Food‐Producing Animals in Japan
Authors: Kijima‐Tanaka M. , Ishihara K. , Kojima A. , Morioka A. , Nagata R. , Kawanishi M. , Nakazawa M. , Tamura Y. , Takahashi T.
Published: August 2005

To assess the public health risk, the prevalence and anti‐microbial resistance of Shiga toxin‐producing Escherichia coli (STEC) among food‐producing animals were studied throughout Japan. Faecal samples were collected from healthy animals of 272 cattle, 179 pigs, and 158 broilers on 596 farms in all 47 Japanese prefectures. STEC were isolated from 62 (23%) cattle and 32 (14%) pig samples but from no chicken samples. Of the bovine isolates, 19 belonged to serotypes frequently implicated in human disease (O157:H7/non‐motile (NM)/H not typeable, O26:NM/H11/H21/H not typeable, O113:H21, and O145:NM). The eae genes were observed in 37% of bovine isolates; among them one O145:NM and all four O157 isolates possessed eae‐γ1, and one O145:NM, one O103:H11, and all five O26 isolates possessed eae‐β1 gene. Among the swine isolates, stx2e were dominant, and serotypes frequently implicated in human diseases or eae‐positive isolates were not observed. Bovine isolates showed less anti‐microbial resistance, but six isolates of 26:NM/H11 and O145:NM were multi‐resistant and may need careful monitoring. Swine isolates showed various resistance patterns; chloramphenicol resistance patterns were more common than in bovine isolates. This first national study of STEC in the Japanese veterinary field should aid our understanding of Japan's STEC status.
A Coprological and Serological Survey for the Prevalence of Ascaridia spp. in Laying Hens
Authors: Martín‐Pacho J. R. , Montoya M. N. , Arangüena T. , Toro C. , Morchón R. , Marcos‐Atxutegi C. , Simón F.
Published: August 2005

Ascaridia galli is a common nematode found in the intestine of domesticated chickens. The objectives of the study were to conduct a coprological and serological survey on the prevalence of ascaridiosis in laying hens of commercial farms. The farms recently adopted a breeding programme, where the hens have access to outdoor pens. Different amounts of Ascaridia eggs were detected in five of seven studied farms, while the other two farms were found to be free from the parasite. Serological tests revealed a seroprevalence of 21.8% (range 7.6–95%). No positive serum samples were detected in the same farms with previous negative coprological analysis. Western blot analyses confirmed the results obtained by the enzyme‐linked immunosorbent assay (ELISA) test. In four experimentally infected hens, a progressive increase of the IgG antibody levels was observed, surpassing the cut‐off point established for ELISA test 6 weeks post‐infection. Serological tests are able to detect the infection before the eggs of the parasite appear in the faeces of infected hens, providing a useful tool to detect infections with Ascaridia spp. in avian farms.
Field Study on Protocols for Evaluation of Teat Skin Conditions
Authors: Zecconi A. , Binda E. , Daprà V. , Hemling T. , Piccinini R.
Published: August 2005

Different protocols to evaluate teat skin status under field conditions based on scoring and on the measurement of pH and hydration of teat skin were evaluated. After determination of the teat score for all eligible animals in a commercial dairy herd, 50 of them were chosen, based on their pre‐trial average teat score, and separated in two groups. Two different post‐dipping products with the same amount of disinfectant, but with a different concentration of emollient were applied. All four teats were assessed with the corneometer and pH probes. A digital picture of each teat skin and teat orifice was taken with a digital camera. Hydration and pH data were analysed by anova with repeated‐measurement factors, while teat skin and apex score patterns, were assessed by the means of Mann–Whitney test; between‐ and within‐group changes were assessed by the mean of Mantel–Haenzel chi‐square statistic. Data showed that teat skin pH and hydration could be assessed under field conditions and they were influenced by teat conditioning. The approach based on evaluating odds for scores, stratified for sampling and for treatment, was found to be a sensitive and informative way to compare the changes between and within treatment groups.
Cytokine‐induced stable neuronal differentiation of human bone marrow mesenchymal stem cells in a serum/feeder cell‐free condition
Authors: Tao Helen , Rao Renuka , Ma David D. F.
Published: August 2005

The characteristics and multilineage differentiation potential of bone marrow mesenchymal stem cells (BM MSC) remain controversial. This study aimed to characterize human BM MSC isolated by plastic adherent or antibody selection and their neuronal differentiation potential using growth factors or chemical inducing agents. MSC were found to express low levels of neuronal markers: neurofilament‐M, β tubulin III, and neuron specific enolase. Under a serum‐ and feeder cell‐free condition, basic fibroblast growth factor, epidermal growth factor, and platelet‐derived growth factor induced neuronal morphology in MSC. In addition to the above markers, these cells expressed neurotransmitters or associated proteins: γ‐aminobutyric acid, tyrosine hydroxylase and serotonin. These changes were maintained for up to 3 months in all bone marrow specimens (N = 6). In contrast, butylated hydroxyanisole and dimethylsulfoxide were unable to induce sustained neuronal differentiation. Our results show that MSC isolated by two different procedures produced identical lineage differentiation with defined growth factors in a serum‐ and feeder cell‐free condition.
Establishment of a chick embryo model for analyzing liver development and a search for candidate genes
Authors: Yokouchi Yuji
Published: August 2005

The liver plays a crucial role in metabolism. There is considerable interest in how the liver develops, as such knowledge could prove of importance in regenerative medicine. However, our understanding of liver development remains somewhat limited. We have developed a model system using the chick embryo that is cost effective and is easy to manipulate experimentally. We performed four fundamental studies: (i) construction of an atlas of the developing chick liver; (ii) identification of differentiation marker genes in the developing chick embryo; (iii) development of germ‐layer specific electroporation; and (iv) establishment of organ culture from the developing chick liver. Using this system, we have been able to demonstrate the functions of candidate genes within a shorter period and in a more cost‐effective manner. In parallel with the establishment of this system, we examined the expression patterns of genes known to be required for organ development in the developing chick embryo in order to identify genes also involved in liver development. To date, we have found sixteen genes that are expressed in the developing chick liver (GELD, genes expressed in liver development). This knowledge will be fundamental to the establishment of the basic technology for engineering liver tissue in the future.
Stem‐cell‐based approaches for regenerative medicine
Authors: Kume Shoen
Published: August 2005

Recent success in transplantation of islets raises the hopes of diabetic patients that replacement therapies may be a feasible treatment of their disease. Although several lines of evidence suggest that stem cells exist in the pancreas, it is still technically hard for us to isolate or maintain the stem cells in vitro. The establishment of human embryonic stem (ES) cells has excited scientists regarding their potential medical use in tissue replacement therapy. When applied with appropriate signals, ES cells can be directed to differentiate into a specific cell lineage. Therefore, ES cells are no doubt an excellent source not only for regenerative medicine but also for studies of early events of pancreatic development, and to portray the pancreatic progenitor cells.

Despite many attempts that have been tried, the efficiency of differentiation of ES cells into islets is still very low. This low efficiency reflects our lack of understanding of the intrinsic and extrinsic signals which regulate the developmental processes of the pancreas. In this review, I present a summary of recent works on ES cells, the identification of pancreatic progenitor cells from the adult pancreas, and refer to the possibilities of transdifferentiation from adult stem cells derived from other tissues.
Endoderm development in vertebrates: fate mapping, induction and regional specification
Authors: Fukuda Kimiko , Kikuchi Yutaka
Published: August 2005

The formation of the vertebrate body plan begins with the differentiation of cells into three germ layers: ectoderm, mesoderm and endoderm. Cells in the endoderm give rise to the epithelial lining of the digestive tract, associated glands and respiratory system. One of the fundamental problems in developmental biology is to elucidate how these three primary germ layers are established from the homologous population of cells in the early blastomere. To address this question, ectoderm and mesoderm development have been extensively analyzed, but study of endoderm development has only begun relatively recently. In this review, we focus on the ‘where’, ‘when’ and ‘how’ of endoderm development in four vertebrate model organisms: the zebrafish, Xenopus, chick and mouse. We discuss the classical fate mapping of the endoderm and the more recent progress in characterizing its induction, segregation and regional specification.
The molecular mechanisms of stomach development in vertebrates
Authors: Fukuda Kimiko , Yasugi Sadao
Published: August 2005

The tissue interactions between endodermal epithelium and mesenchyme originated from splanchnic mesoderm are essential during the formation of digestive tract. In this review, we introduce a series of works to elucidate the molecular mechanisms of the epithelial–mesenchymal interaction of stomach development in mainly the chicken embryo. We also describe some molecular studies in mouse stomach development.
Modulation of leaf economic traits and trait relationships by climate
Authors: Wright Ian J. , Reich Peter B. , Cornelissen Johannes H. C. , Falster Daniel S. , Groom Philip K. , Hikosaka Kouki , Lee William , Lusk Christopher H. , Niinemets Ülo , Oleksyn Jacek , Osada Noriyuki , Poorter Hendrik , Warton David I. , Westoby Mark
Published: August 2005

Aim  Our aim was to quantify climatic influences on key leaf traits and relationships at the global scale. This knowledge provides insight into how plants have adapted to different environmental pressures, and will lead to better calibration of future vegetation–climate models.

Location  The data set represents vegetation from 175 sites around the world.

Methods  For more than 2500 vascular plant species, we compiled data on leaf mass per area (LMA), leaf life span (LL), nitrogen concentration (Nmass) and photosynthetic capacity (Amass). Site climate was described with several standard indices. Correlation and regression analyses were used for quantifying relationships between single leaf traits and climate. Standardized major axis (SMA) analyses were used for assessing the effect of climate on bivariate relationships between leaf traits. Principal components analysis (PCA) was used to summarize multidimensional trait variation.

Results  At hotter, drier and higher irradiance sites, (1) mean LMA and leaf N per area were higher; (2) average LL was shorter at a given LMA, or the increase in LL was less for a given increase in LMA (LL–LMA relationships became less positive); and (3) Amass was lower at a given Nmass, or the increase in Amass was less for a given increase in Nmass. Considering all traits simultaneously, 18% of variation along the principal multivariate trait axis was explained by climate.

Main conclusions  Trait‐shifts with climate were of sufficient magnitude to have major implications for plant dry mass and nutrient economics, and represent substantial selective pressures associated with adaptation to different climatic regimes.