bluuebunny/crossref_metadata_2025 huggingface dataset:
Markers for benzimidazole resistance in human parasitic nematodes?
Authors: PRICHARD ROGER K.
Published: July 2007

Benzimidazole (BZ) resistance is widespread and appears to be readily selected in a variety of nematode parasites of animals. There have been reports of a lack of efficacy of BZ anthelmintics against soil transmitted nematode parasites of humans. However, resistance to BZs in nematodes of humans has not been confirmed. It is difficult to perform tests to confirm anthelmintic resistance in humans for a variety of technical and ethical reasons. The use of anthelmintic drugs for the control of helminth parasites in people is increasing massively as a result of numerous programmes to control gastrointestinal nematode parasites in children, the Global Program for the Elimination of Lymphatic Filariasis and other programmes. Many of these programmes are dependent on BZ anthelmintics and this will increase the pressure for resistance development to BZ anthelmintics in nematode parasites of people. We need to perform monitoring for anthelmintic resistance in these programmes and we need new tools to make that monitoring sensitive, inexpensive and practical. There is a real need for DNA-based markers for BZ resistance in nematode parasites of humans. We have a reasonable understanding of the molecular mechanisms and genetics of BZ resistance in some nematode parasites of animals and similar mechanisms are likely to prevail in nematodes of humans. Based on the likelihood that similar single nucleotide polymorphisms (SNPs) will be involved in BZ resistance in human, as in animal nematode parasites, rapid SNP assays have been developed for possible BZ resistance development in Wuchereria bancrofti.
Origin and maintenance of germ‐line V genes
Authors: ROTHENFLUH HARALD S. , STEELE EDWARD J.
Published: July 2007

The distribution of nucleotide variability within and upstream of germ‐line VH186.2‐related variable genes was studied. The data in this report of work in progress indicate non‐random selection for variability in the second antigen‐contact or complementarity‐determining region (CDR2) for 12 such genes isolated using the polymerase chain reaction (PCR) technique from genomic C57BL/6 mouse liver DNA. The translated protein sequences of these and three additional previously published genes also display a pronounced Wu‐Kabat peak of amino acid variability in CDR2. In the CDR1 and CDR2 regions of this set of related germ‐line genes, there are no silent nucleotide changes, and most amino acid replacements (or non‐synonymous changes) are non‐conservative. In contrast, there is selection against amino acid replacements in the framework regions (FW), as indicated by the significant number of silent (or synonymous) mutational changes from the VH 186.2 reference sequence. This is surprisingly similar to the Wu‐Kabat variability patterns observed in somatically mutated immune response antibodies. These data could imply similar diversification mechanisms acting on B cell‐expressed V genes in the soma (i.e. in a germinal centre) and in the germ‐line DNA of male and/or female germ cells. While always possible, we consider this unlikely. Similarly, we consider as unlikely an explanation based on a classical Darwinian model involving simple stepwise whole animal selection prior to reproduction for each VH and VL gene now phylogenetically stored in the V segment arrays of the genomic DNA. A more reasonable hypothesis for the origin and maintenance of the many germ‐line V genes would propose that there is a yet to be defined process providing a direct genetic link between somatically mutated and selected V genes and the germ‐line DNA repertoire.
Expression of membrane receptor for tumour necrosis factor on human blood lymphocytes
Authors: ZOLA H. , FLEGO L. , WEEDON H.
Published: July 2007

Using a monoclonal antibody against the human p75 tumour necrosis factor receptor (TNFR‐I) combined with a high‐sensitivity immunofluorescence flow cytometric procedure, a proportion of peripheral blood lymphocytes can be shown to express TNFR‐I constitutively. Approximately 50% of peripheral blood lymphocytes consisting mostly of CD4 cells and including most CD45R0‐positive cells, express TNFR‐I. Receptor expression is increased by a variety of activation signals. Only a minority (up to 30%) of tonsil B cells express measurable levels of TNFR‐I. The tonsil B cells which express TNFR‐I include both cells with a germinal centre cell phenotype and cells with the phenotype of the follicular mantle zone. Activation of B cells with antiimmunoglobulin, alone or in combination with interleukin‐4 or interleukin‐2, increases receptor expression, particularly in cells with the phenotype of mantle zone cells. The functional significance of constitutive expression of TNFR by blood and tissue lymphocytes is discussed.
Control of clonal deletion in the thymus: Implications for tolerance induction
Authors: HARTWIG MANFRED
Published: July 2007

Tolerance to foreign antigen by means of clonal deletion in the thymus can be achieved during embryonic or neonatal life, but not easily in the adult animal. It is concluded here that an immunological control by mature T cells prevents newly acquired antigen from being permanently deposited in the adult thymus. In this way, the originally established thymic antigen discrimination can be maintained successfully. Breakdown of the control circuit should permit tolerance induction even in the adult thymus.
Molecular cloning and characterization of a ruminant interleukin‐6 cDNA
Authors: ANDREWS ARNA E. , BARCHAM GARRY J. , ASHMAN KEITH , MEEUSEN ELS N. T. , BRANDON MALCOLM R. , NASH ANDREW D.
Published: July 2007

By hybridization with a human interleukin‐6 (IL‐6) cDNA fragment a corresponding ruminant (ovine) cDNA was isolated from a lipopolysaccharide (LPS)‐stimulated alveolar macrophage library. The nucleotide sequence of the cDNA and the predicted amino acid sequence of the protein showed significant homology to the human and murine molecules. Ovine IL‐6 cDNA encodes a polypeptide of 208 amino acids that, based on analysis of human IL‐6, is processed to a protein of 180 amino acids. Northern blot analysis and the 7TD1 bioassay were used to analyse regulatory aspects of IL‐6 production by primary ovine fibroblasts. Both LPS and recombinant ovine IL‐1α were shown to induce IL‐6 mRNA with peak levels occurring at 1 h post‐stimulation and declining thereafter. When fibroblasts were pretreated with cyclohexamide prior to stimulation the level of induction by LPS and IL‐1α increased dramatically and peak levels were observed at 5 h post‐stimulation. The level of secreted IL‐6 increased rapidly over the first 24 h and continued to increase over the next 48 h.
Inhibition by anti‐sperm monoclonal antibodies of the penetration of zona‐free hamster oocytes by human spermatozoa
Authors: GARCÍA‐FRAMIS V. , MARTORELL R. , MARQUEZ C. , BENET J. , ANDOLZ P. , MARTINEZ P.
Published: July 2007

Fourteen mAb specific for human sperm membrane antigens were selected to investigate their inhibitory effect on fertilization. The antigens were not expressed in other human somatic tissues but were present in sperm from other species. The antibodies were purified from ascites fluid produced in mice. The zona‐free hamster egg penetration assay was used for the evaluation of the blocking ability of these antibodies. The inhibition rate was generally related to a decrease in the number of adherent sperm. Three groups of antibodies were distinguished: (i) four mAb that have high inhibition at concentration; (ii) four mAb with an intermediate inhibitory effect, that is more dependent on the antibody concentration tested; and (iii) six mAb with little or no effect at any concentration. The presence of antibodies leads to a lower penetration index, or number of penetrating sperm per oocyte.

MAb specific for head antigens promote high inhibition of fertilization; these antibodies show a patchy staining on the sperm head. The antibodies localized in the midpiece have an intermediate inhibitory effect. No inhibition is detected with the equatorial region binding pattern. Sperm agglutination does not play any role in the inhibition caused by the antibodies described here.
Molecular associations involving CD 16, CD45 and ζ, and γ chains on human natural killer cells
Authors: ALTIN JOSEPH G. , PAGLER ELOISA B. , KINNEAR BEVERLEY F. , WARREN HILARY S.
Published: July 2007

ζ (CD3‐ζ) and γ (FcεRIγ) chains associate with CD 16. the low affinity receptor for IgG (FcλRIII) on human NK cells and are essential for the cell surface expression of CDI6 and for CD16‐mediated effector functions. This study has investigated whether, on NK cells, molecules other than CD16 associate with ζ, and γ chains, as a method of identifying other NK cell surface molecules important in NK cell function. Cell surface biotinylated NK cells were lysed in digitonin, and the lysates immunoprecipitated with mAb to CD 16, ζ, and γ and the immunoprecipitates analysed by SDS‐PAGE. CD 16 mAb co‐precipitated ζ and γ chains (16 and 12kD. respectively) and in addition molecules of 24. 32–35, 100, 150 and 180–200 kD. Also, C, mAb co‐precipitated ζ chain, and molecules of 24–26, 32–35. 48, 50–66, 100, 150 and 180–200 kD; and γ co‐precipitated ζ, chain, and molecules of 24–26, 29, 32–35, 37, 45, 49, 50–66 and 100 kD. While significant amounts of ζ, and γ were co‐precipitated with CD 16, 10 to 12‐fold more ζ and γ were immunoprecipitated with their respective mAb. Furthermore, depletion of CD 16 from the lysate resulted in only a partial (10–12%) depletion of ζ, and γ indicating that only a relatively small proportion (10–12%) of these molecules are associated with CD 16. Interestingly, substantial amounts of molecules with electrophoretic mobility similar to CD16 (50–66 kD) were co‐precipitated with ζ, and γ chain mAb from lysates depleted of CD16. In contrast to NK cells where I, associated with a number of different molecules, the majority of ζ, in T cells was found to be associated only with the TCR: CD3 complex. NK cells showed a strong association between CD45, CD 16 and a 33 kD molecule and often a strong association of ζ, with CD l6, CD45 and an unidentified molecule of −150 kD. Our results show first, that CD16, ζ and γ each can be efficiently labelled by cell surface biotinylation, and second, that CD 16, C, and γ each can form a complex with each other, and with a number of additional molecules including a 33 kD molecule and CD45 potentially important in NK cell function.
A 3.5 kb deletion in the glycophorin C gene accounts for the Gerbich‐negative blood group in Melanesians
Authors: SERJEANTSON S. W. , WHITE B. S. , BHATIA K. , TRENT R. J.
Published: July 2007

The Gerbich‐negative blood group types are rare in most populations, but reach appreciable frequencies in certain Melanesian groups in Papua New Guinea. The recent cloning of the human glycophorin C (GPC) gene, that encodes Gerbich (Ge) blood group antigens, has facilitated study of its genetic variants. We have obtained partial genomic clones of a normal GPC gene, for molecular analysis of Ge: −1,−2,−3 types in Melanesians, and have shown that a 3.5 kb deletion in the GPC gene that removes all of exon 3 accounts for at least one Gerbich‐negative phenotype in Melanesians. Population distributions of GPC RFLP have shown that the deletion‐type GPC is not confined to mainland Papua New Guinea as previously thought, but occurs sporadically in Melanesians from Fiji as well as in Micronesians.
Co‐selection in immune network theory and in AIDS pathogenesis
Authors: HOFFMANN GEOFFREY W.
Published: July 2007

Co‐selection is a term used to denote the mutual positive selection of individual members from within two diverse populations, such that selection of members within one population is dependent on interaction with (recognition of) one or more member(s) within the other population. Co‐selection is a recurring theme of the idiotypic network model that my colleagues and I have developed. This paper discusses the role that co‐selection plays in basic symmetrical network theory and in a network model that resolves the I‐J paradox. It proposes that co‐selection of helper T cells and HIV variants plays a role in the pathogenesis of AIDS. The AIDS model involves a role for the T cell receptor in the infection of T cells. Finally, a way in which a co‐selection process may potentially be used in the prevention and therapy of harmful forms of immunity is described.
Metabolic consequences of methotrexate therapy in tumour‐bearing rats
Authors: ROFE A. M. , BOURGEOIS C. S. , WASHINGTON J. M. , PHILCOX J. C. , COYLE P.
Published: July 2007

The metabolic response of the tumour‐bearing host to methotrexate (MTX) therapy was investigated with particular attention to effects resulting from MTX‐induced anorexia. Biochemical changes in female Dark Agouti rats bearing mammary adenocarcinomas and treated with MTX (0.5 mg/kg. 2 i.m. injections, 24 h apart) were compared with untreated (CON) tumour‐bearing rats, and tumour‐bearing rats pair‐fed (PF) to the MTX group. MTX treatment halted progression of the tumour (tumour 6% of bodyweight) while the tumour burden doubled in the CON and PF groups.

A number of biochemical and haematological changes were specific to MTX treatment and did not result from decreased food intake. MTX treatment was associated with significantly decreased plasma calcium, bilirubin, alkaline phosphatase, aspartate aminotransferase and the total white cell count. Decreases in plasma albumin and total protein concentrations were observed in both MTX and PF rats. Other parameters commonly used to assess renal and liver function were not significantly affected by MTX.

MTX reversed the hypoglycaemia, hyperketonaemia and hypertriglyceridaemia induced by tumour‐bearing. In contrast, PF rats had an even more pronounced hypoglycaemia and hyperketonaemia than the CON rats. Measurement of glucose uptake in vivo with 2‐deoxy[U‐14C]‐glucose showed that MTX treatment halved the glucose requirement of the tumour (8.2% of bodyweight compared to 12.2% in the control). It is concluded that the potentially adverse effects of MTX treatment on host metabolism are outweighed by the beneficial effects of a reduced metabolic demand resulting from inhibition of tumour progression.
Antigen‐specific B cells in tissues after oral typhoid vaccination
Authors: GIBSON C. E. , PENTTILA I. A. , LEONG A. S‐Y. , ZOLA H. , LABROOY J. T.
Published: July 2007

Six human subjects who were to receive elective bowel surgery for a variety of diseases were vaccinated with the oral typhoid vaccine, Ty21a. Intestinal tissue (ileum in two, large intestine in four) removed 7‐26 days after the first dose of vaccine was examined for the presence and distribution of antigen‐specific B cells. This was compared with intestinal tissue derived from two unvaccinated controls. A number of B cell differentiation antigens were also assessed on these cells by immunofluorescence using dual‐labelling. Antigen‐specific cells were found randomly distributed in the lamina propria of all the vaccinated subjects in low frequency (6 ± 0.5 to 37 ± 31 [mean ± s.e.m.] antigen specific cells/10 mm2 of tissue). The lymphocyte differentiation antigens CD45RA, CD45RO. L‐selectin, CD‐1 la CD‐38, CD‐44 and VLA‐4 were all found on antigen‐specific cells, but no particular pattern was recognizable in this small series of six subjects with different disease processes affecting the intestine.
Peptide mimotopes selected with HIV‐1‐blocking monoclonal antibodies against CCR5 represent motifs specific for HIV‐1 entry
Authors: Königs Christoph , Pustowka Anette , Irving James , Kessel Christoph , Klich Katharina , Wegner Valérie , Rowley Merrill J , Mackay Ian R , Kreuz Wolfhart , Griesinger Christian , Dietrich Ursula
Published: July 2007

CCR5 is a chemokine receptor that mediates entry of human immunodeficiency virus‐1 (HIV‐1). Two monoclonal antibodies (mAbs) that block HIV‐1 entry, 3A9 and 5C7, were used to select peptide mimotopes of sequences on CCR5 from phage displayed peptide libraries. The selected mimotofpes comprised motifs at the N‐terminus and on the first and third extracellular loops (ECL1 and ECL3) of CCR5. Amino acids in these motifs were exchanged for alanines by site‐directed mutagenesis (sdm) in the cDNA for human CCR5. Ensuing effects on antibody binding to CCR5, cellular entry of HIV‐1 and chemokine‐induced signalling were analysed by transfection of mutant cDNAs into HEK293.CD4 cells. For both mAbs, fluorescence‐activated cell sorting analysis was used to define overlapping conformational epitopes on CCR5 at the N‐terminus, on ECL1 and ECL3. Mutation of the N‐terminal motif 10YD11 prevented HIV‐1 entry into transfected cells as judged by single round infection assays with R5 and R5X4 HIV‐1 isolates, as did mutation of the motif 96FG97 in ECL1, whereas mutation of the motif 274RLD276 in ECL3 had only a minor effect. None of the motifs in CCR5 relevant to HIV‐1 entry disrupted chemokine‐induced signalling. Thus, peptide mimotopes of conformational contact sites of CCR5 with the paratope of mAbs 3A9 and 5C7 represent sites on CCR5 that are essential for HIV‐1 entry. Structural knowledge of these mimotopes could help elucidate the nature of the interaction between CCR5 and HIV‐1, and thus the derivation of specific inhibitors of entry of HIV‐1 into susceptible cells without interference with chemokine signalling.
B and T lymphocyte attenuator interacts with CD3ζ and inhibits tyrosine phosphorylation of TCRζ complex during T‐cell activation
Authors: Wu Ting‐He , Zhen Yu , Zeng Chun , Yi Huan‐Fa , Zhao Yong
Published: July 2007

B and T lymphocyte attenuator (BTLA) is an important negative regulator of T‐cell activation. T‐cell activation involves partitioning of receptors into discrete membrane compartments known as lipid rafts and the formation of an immunological synapse (IS) between the T cell and antigen‐presenting cell (APC). Here we show that after T‐cell stimulation, BTLA co‐clusters with the CD3ζ and is then involved in IS, as determined by a two‐photon microscope. BTLA can interact with the phosphorylated form of T‐cell receptor (TCR) within the lipid raft, which is associated with the T‐cell signaling complex. Coligation of BTLA with the TCR significantly decreased the amount of phosphorylated TCR‐related signal accumulation in the lipid raft during T‐cell activation. These results suggest that BTLA functions to regulate T‐cell signaling by controlling the phosphorylated form of TCRζ accumulation in the lipid raft.
Toll‐like receptors: structural pieces of a curve‐shaped puzzle
Authors: Huyton Trevor , Rossjohn Jamie , Wilce Matthew
Published: July 2007

The toll‐like receptors are responsible for recognizing invading pathogens and triggering a primary innate immune response by initiating a signalling pathway that ultimately leads to the activation of nuclear factor‐κB (NF‐κB). NF‐κB induces the transcription of many genes that regulate both the inflammatory response and interferons that help control the development of adaptive immunity. In this review, we concentrate on the structure and function of toll‐like receptors and our current understanding of the complexities of ligand binding, receptor dimerization and signal transduction.
Formation of dynamic particle accumulation structures in oscillatory thermocapillary flow in liquid bridges
Authors: Schwabe D. , Mizev A. I. , Udhayasankar M. , Tanaka S.
Published: July 2007

We report on the behavior of small particles of dilute concentration in time-dependent (oscillatory) thermocapillary flow in cylindrical liquid bridges. The particles accumulate in a dynamic string for certain aspect ratios of the liquid bridge and at, typically, two times the critical Marangoni number for the onset of time dependence. This was observed for particles with a density larger and smaller than that of the fluid and for the isodense case. If looked at in a snapshot, this string would be wound m times around the thermocapillary vortex as a deformed spiral. If one looked at the full dynamics, it would be seen that the spiral string is rotating around its ring-shaped axis. The phenomenon is called a dynamical particle accumulation structure (dynamical PAS). The mode m is the mode number of the oscillatory flow field with m wavetrains of the hydrothermal wave (HTW) traveling in the azimuthal direction. We visualize and describe the different modes m in detail. We give direct experimental evidence for the gathering of liquid with particles during the cold phases of the HTW and the injection of liquid with particles into the return flow in azimuthally traveling “cold spots.” We varied the particle diameter at constant density and the ratio of the particle density to fluid density at constant particle diameter to measure the time of the formation of PAS and discuss and explain the experimental results in comparison with possible mechanisms underlying the formation process. We describe the results of an experiment under microgravity to exclude gravity as a PAS-forming mechanism. We conclude by describing a possible mechanism that could account for the observed particle accumulation in certain regions of the flow. This mechanism involves the observed gathering and injection of liquid during the cold phases of the HTW and the particle enrichment of the injected fluid due to particle migration in sheared flow. PAS occurs at a resonance between the azimuthally traveling wave and the “turnover time” of the PAS-string in the thermocapillary vortex.
Adiabatic plasma equilibrium and application to a reconnection problem
Authors: Zaharia Sorin , Birn J.
Published: July 2007

The evolution of many plasma systems is adiabatic, i.e., plasma entropy is conserved in each magnetic flux tube. An apparently surprising result found recently from simulations of a forced magnetic reconnection problem (the “Newton Challenge” [J. Birn et al., Phys. Plasmas 13, 092117 (2006)]) is that even in the presence of a dissipative process such as reconnection, the entropy within a flux tube can still be approximately conserved, due to the strong localization of the dissipation. To address plasma equilibrium with such adiabatic constraints, a novel code has been developed that computes equilibria with entropy profile as input, using the alternating dimension method [H. Grad et al., Proc. Natl. Acad. Sci. USA 72, 3789 (1975)]. The code alternates between solving the two–dimensional (2D) Grad-Shafranov equation to obtain the field configuration (flux function A) from the pressure profile P(A) and a 1D ordinary differential equation that uses the entropy conservation to derive the pressure function P(A) from a flux surface average. As a particular application, the code is used to compute equilibria relevant to the Newton Challenge, with a grid reflecting the reconnected state topology (with an X and an O point). The equilibria found agree very well with late stages of magnetohydrodynamic simulations of the Newton Challenge. This agreement not only validates the new code, but also proves that the final state approached by the reconnection simulations is indeed an equilibrium quasiadiabatically connected with the initial state. The results also show a significant release of magnetic energy through reconnection. Finally, other potential applications of the new code, especially to adiabatic evolution of space plasmas, are discussed.
Multistaged acceleration of ions by circularly polarized laser pulse: Monoenergetic ion beam generation
Authors: Zhang Xiaomei , Shen Baifei , Li Xuemei , Jin Zhangying , Wang Fengchao
Published: July 2007

A multiple-staged ion acceleration mechanism in the interaction of a circularly polarized laser pulse with a solid target is studied by one-dimensional particle-in-cell simulation. The ions are accelerated from rest to several MeV monoenergetically at the front surface of the target. After all the plasma ions are accelerated, the acceleration process is repeated on the resulting monoenergetic ions. Under suitable conditions multiple repetitions can be realized and a high-energy quasi-monoenergetic ion beam can be obtained.
Hardware comb filter enhances dynamic range and noise performance of sensors in noisy environments
Authors: Prance H. , Prance R. J. , Stiffell P. B.
Published: July 2007

We present the results of combining a hardware implementation of an analog comb filter with an ultralow noise electromagnetic sensor. The comb filter is designed to attenuate mains related interference, at either 50 or 60Hz, and related harmonics. The sensor chosen for this work is an induction magnetometer, but the method is applicable to any low noise high dynamic range sensor. The resultant system, in this case, uses only a single coil, not a gradiometric configuration, thus providing a magnetometer capable of sensing field as opposed to field gradient. This combination of filter and sensor allows additional gain to be added and the full sensitivity of the system to be achieved, previously only realized in an electromagnetically screened room. At the same time, the high dynamic range, low noise performance, and original bandwidth of the sensor are maintained. The technique is illustrated by using the system in an urban environment to observe Schumann resonance phenomena. This approach to acquiring small signals in a noisy environment is compared with conventional analog filter and digital signal processing techniques.
Amendment of cavity perturbation technique for loss tangent measurement at microwave frequencies
Authors: Sheen Jyh
Published: July 2007

Theoretically, the quality factor of a metal resonant cavity will be increased after introducing a lossless dielectric sample. However, this increment of quality factor is not put into the consideration of the calculation of loss tangent measurement for the conventional cavity perturbation method, widely used on the measurements of microwave dielectric properties. Therefore, the conventional resonant perturbation formulas for dielectric loss measurement should be amended. This amendment is introduced in this study and the amended formulas for loss tangent measurement are given. With the amended formulas, no standard sample is required for measurement which simplifies the measuring procedure suggested by the previous publication. In addition, the measuring error on loss tangent on the conventional formula is discussed. Experiments have shown the improvement of measurement accuracy by this modification.
Ferrimagnetic and half-metallic CaCu3Fe4O12: Prediction from first principles investigation
Authors: Xiang H. P. , Liu X. J. , Zhao E. J. , Meng J. , Wu Z. J.
Published: July 2007

The structural stability and physical properties of CaCu3Fe4O12 were studied by the use of the full-potential linearized augmented plane wave method. The authors’ calculated result indicates that the title compound is stable both thermodynamically and mechanically. It is ferrimagnetic and half-metallic. The calculated magnetic structure reveals that the coupling of Cu–Fe is antiferromagnetic, while those of Cu–Cu and Fe–Fe are ferromagnetic.
Dielectric properties of single-walled carbon nanotubes in the terahertz frequency range
Authors: Nishimura Hisaaki , Minami Nobutsugu , Shimano Ryo
Published: July 2007

The authors report on the terahertz time-domain spectroscopy of single-walled carbon nanotubes (SWCNTs) dispersed in a polymer film in a broad frequency range from 0.2to20THz. The complex dielectric function of the composite film is obtained without using Kramers-Kronig analysis, from which the dielectric function of SWCNTs is extracted by using the effective medium theory. The real part of the dielectric function exhibits very large values at low frequency below 2THz. The conductivity spectrum shows a peak around 3THz. The spectral behavior is consistent with overdamped Lorentz oscillator model, indicating the response of curvature-induced small-gap SWCNTs.
Wildland - urban interface housing growth during the 1990s in California, Oregon, and Washington
Authors: Hammer Roger B. , Radeloff Volker C. , Fried Jeremy S. , Stewart Susan I.
Published: July 2007

In the present study, we examine housing growth in California, Oregon, and Washington in the wildland–urban interface (WUI), the area where homes and other structures abut or intermingle with wildland vegetation. We combine housing density information from the 1990 and 2000 USA censuses with land cover information from the 1992/93 National Land Cover Dataset to demarcate the location and extent of the WUI and its growth, both in terms of area and number of housing units during the 1990s. We overlay the WUI with coarse-scale fire regime condition class information to evaluate implications for wildland fire management. During the 1990s, WUI area in the three-state region increased by 5218 km2 (10.9%) to nearly 53 000 km2 and the number of housing units in the WUI increased over 1 million units (17.6%) and in 2000 encompassed 6.9 million units, 43% of all housing in the region. Over a million new homes were constructed in the WUI, comprising 61% of the new homes constructed in the region. By 2000, there was far more intermix WUI (75% of the WUI area and 64% of the WUI housing units) than interface WUI. Expansion of the WUI accounted for only 13% of WUI housing unit growth and WUI that existed in 1990 encompassed 98% of WUI housing units in 2000. In 2000, there were nearly 1.5 million WUI housing units in areas with 0–35-year fire return intervals and 3.4 million in areas with 35–100+ year fire return intervals. In both these fire regimes, the majority of WUI housing units (66% and 90% respectively) are in areas with a current condition outside the historic range of variability. Housing growth patterns in this three-state region are exacerbating wildland fire problems in the WUI. Any long-term solution to wildland fire issues in the western United States will have to address housing growth patterns. Using a consistent, nationally applicable assessment protocol, the present study reveals the vast extent of WUI in the west coast states and its growth in the 1990s, and provides a foundation for consistent monitoring efforts.
Integrating new methods and tools in fire danger rating
Authors: Vasilakos Christos , Kalabokidis Kostas , Hatzopoulos John , Kallos George , Matsinos Yiannis
Published: July 2007

Prevention is one of the most important stages in wildfire and other natural hazard management regimes. Fire danger rating systems have been adopted by many developed countries dealing with wildfire prevention and pre-suppression planning, so that civil protection agencies are able to define areas with high probabilities of fire ignition and resort to necessary actions. This present paper presents a fire ignition risk scheme, developed in the study area of Lesvos Island, Greece, that can be an integral component of a quantitative Fire Danger Rating System. The proposed methodology estimates the geo-spatial fire risk regardless of fire causes or expected burned area, and it has the ability of forecasting based on meteorological data. The main output of the proposed scheme is the Fire Ignition Index, which is based on three other indices: Fire Weather Index, Fire Hazard Index, and Fire Risk Index. These indices are not just a relative probability for fire occurrence, but a rather quantitative assessment of fire danger in a systematic way. Remote sensing data from the high-resolution QuickBird and the Landsat ETM satellite sensors were utilised in order to provide part of the input parameters to the scheme, while Remote Automatic Weather Stations and the SKIRON/Eta weather forecasting system provided real-time and forecasted meteorological data, respectively. Geographic Information Systems were used for management and spatial analyses of the input parameters. The relationship between wildfire occurrence and the input parameters was investigated by neural networks whose training was based on historical data.
Problems, paradoxes, paradigms: triangulating fire research
Authors: Pyne Stephen J.
Published: July 2007

Wildland fire research has historically orbited around a physical paradigm of fire. This strategy has yielded remarkable results, yet increasingly it cannot speak to the core issues that concern fire management. Two additional paradigms are needed. One would build on fire’s origins in the living world. The other would evolve out of fire’s significance to humanity, and humanity’s unblinking importance to fire’s presence on Earth. Note that each paradigm is coherent in itself, that each is capable of absorbing the others, and that each is insufficient on its own. It is unlikely that a master synthesis of these conceptions will emerge, and is not necessary. The need is to sustain research that addresses how fire really exists, not how select sciences can handle it. This essay sketches what the resulting fire-research triangle might look like.
Thermal infrared emission - transmission measurements in flames from a cylindrical forest fuel burner
Authors: Dupuy Jean-Luc , Vachet Philippe , Maréchal Joël , Meléndez Juan , de Castro Antonio J.
Published: July 2007

We describe emission–transmission measurements performed at different heights in a flame from a cylindrical forest fuel burner, using a camera operating in the thermal infrared (7.5–13 µm). The forest fuel burner was made of a cylindrical wire mesh basket filled with a forest fuel (Pinus pinaster needles), which was ignited at the base of the basket. Three diameters of basket were used (20, 28 and 40 cm). Heat release rates, as calculated from weighing of the basket and heat of combustion of the fuel, ranged between 50 and 170 kW and flame heights ranged between 1 and 2 m. The emission–transmission device allows the determination of the transmittance of the flame and of a radiometric temperature. We show that radiation was dominated by soot in the spectral range of the camera, but that radiation from gaseous products of the combustion was not negligible. Using the Mie theory in its Rayleigh limit, we deduced some average volume fractions of soot from the measurements, which peaked at 6.8 × 10−6 in the persistent region of the flame. Then the total extinction coefficient and the total emissivity of the flame due to soot were calculated according to a standard method. Measured transmittance, soot volume fraction, total extinction coefficient and total emissivity were found to scale with the normalised height of measurement Z, defined as the ratio of the height of measurement to the height of the flame (0.25 < Z < 1.6).
A simulation model of the growth and suppression of large forest fires in Ontario
Authors: Podur Justin J. , Martell David L.
Published: July 2007

Most of the area burned by forest fires in Canada is due to the few fires that escape initial attack and become large. We developed a discrete event simulation model of the growth and suppression of large fires in the province of Ontario. Based on fire, weather and suppression data from the Ontario Ministry of Natural Resources, our model includes a logistic regression component to predict the probability that a fire will escape initial attack and burn more than 100 ha, a component that simulates the growth of large fires based on weather and forest vegetation, and a component that simulates fire suppression by firefighters and aircraft. We used our model to predict area burned under mild and severe weather with varying levels of fire suppression resources. We found that, although severe weather limits fire suppression effectiveness, suppression has a significant effect on area burned even during severe fire seasons.
Cardiac beat-to-beat alternations driven by unusual spiral waves
Authors: Kim Tae Yun , Woo Sung-Jae , Hwang Seong-min , Hong Jin Hee , Lee Kyoung J.
Published: July 2007

Alternans, a beat-to-beat temporal alternation in the sequence of heartbeats, is a known precursor of the development of cardiac fibrillation, leading to sudden cardiac death. The equally important precursor of cardiac arrhythmias is the rotating spiral wave of electro-mechanical activity, or reentry, on the heart tissue. Here, we show that these two seemingly different phenomena can have a remarkable relationship. In well controlled
in vitro
tissue cultures, isotropic populations of rat ventricular myocytes sustaining a temporal rhythm of alternans can support period-2 oscillatory reentries and vice versa. These reentries bear “line defects” across which the phase of local excitation slips rather abruptly by 2π, when a full period-2 cycle of alternans completes in 4π. In other words, the cells belonging to the line defects are period-1 oscillatory, whereas all of the others in the bulk medium are period-2 oscillatory. We also find that a slowly rotating line defect results in a quasi-periodic like oscillation in the bulk medium. Some key features of these phenomena can be well reproduced in computer simulations of a nonlinear reaction-diffusion model.
Peripheral deletion of mature alloreactive B cells induced by costimulation blockade
Authors: Li Yijin , Ma Lianli , Shen Jikun , Chong Anita S.
Published: July 2007

Alloreactive B cells can contribute to graft rejection. Anti-CD154 treatment together with donor-specific transfusion (DST) results in the long-term survival of MHC-mismatched mouse heart grafts and inhibition of alloantibody production. To characterize the mechanism of B cell tolerance induced by the anti-CD154 and DST, we used 3-83Igi mice, on BALB/c (H-2K
d
) background, that express a B cell receptor that reacts with MHC class I antigens H-2K
b
. Transplanting C57BL/6 (H-2K
b
) hearts into 3-83Igi mice, followed by tolerance induction, resulted in the peripheral deletion of mature but not immature 3-83 B cells. The sustained deletion of mature alloreactive B cells required the presence of the allograft and can be explained by the absence of T cell help.
Learning how to learn: the dynamic assessment of learning power
Authors: Deakin Crick Ruth
Published: July 2007

This article introduces the notion of the assessment of ‘learning power’ as an important station in a mentored learning journey, which begins with the motivation and identity of the person who is learning, and moves through the awareness and development of the power to learn, to the publicly valued competencies and funds of knowledge of the formal curriculum. The seven dimensions of learning power are described, and the article reports on the findings of a qualitative study in which sixteen teachers were provided with learning power assessment data for their students as individuals and as whole groups. There were ten pedagogical themes which underpinned the teaching and learning encounters in those classrooms; these are briefly described. Learning power profiles have been used with nearly nine thousand students since 2003 and data from school‐based development projects are referred to. The article concludes that the dynamic assessment of learning power serves three pedagogical purposes. First, it reflects back to the learner what they say about themselves in relation to their personal power to learn. Second, it reflects back to the teacher data about individuals, and groups, which can be used for diagnosing what is needed to move forward in the development of self‐awareness, ownership and responsibility for learning. Third, it provides scaffolding for ways in which the students encountered the formal content of the curriculum. All of these operate together through the shared, and sometimes locally created, language stimulated by the learning dimensions, and through metaphors, icons and heroes which carry meaning in the classroom.
Cerebellar neurodegeneration in the absence of microRNAs
Authors: Schaefer Anne , O'Carroll Dónal , Tan Chan Lek , Hillman Dean , Sugimori Mutsuyuki , Llinas Rodolfo , Greengard Paul
Published: July 2007

Genome-encoded microRNAs (miRNAs) are potent regulators of gene expression. The significance of miRNAs in various biological processes has been suggested by studies showing an important role of these small RNAs in regulation of cell differentiation. However, the role of miRNAs in regulation of differentiated cell physiology is not well established. Mature neurons express a large number of distinct miRNAs, but the role of miRNAs in postmitotic neurons has not been examined. Here, we provide evidence for an essential role of miRNAs in survival of differentiated neurons. We show that conditional Purkinje cell–specific ablation of the key miRNA-generating enzyme Dicer leads to Purkinje cell death. Deficiency in Dicer is associated with progressive loss of miRNAs, followed by cerebellar degeneration and development of ataxia. The progressive neurodegeneration in the absence of Dicer raises the possibility of an involvement of miRNAs in neurodegenerative disorders.
India's Physics and Chemistry Nobel Prize nominators and nominees in colonial and international context
Authors: Singh Rajinder
Published: July 2007

In India the development of modern science is closely related to its colonial background, a subject well documented by historians. So far as the prestigious Nobel Prizes are concerned, little has been mentioned in the colonial context. This article shows that in the first half of the twentieth century only a few Indian physicists and chemists were either nominees or nominators. Some of them were Fellows of the Royal Society. A comparison of Indian Nobel Prize nominators and nominees with other so-called Third World countries and colonies suggests some interesting results, for example the similarities of development of physics and chemistry in the colonized and ruling countries. The present article also suggests that the election of the Fellows of the Royal Society from India, in the fields of physics and chemistry, reveals a pattern comparable with that of Nobel Prize nominations and nominees.
Context matters: female aggression and testosterone in a year-round territorial neotropical songbird (
Thryothorus leucotis
)
Authors: Gill Sharon A , Alfson Elizabeth D , Hau Michaela
Published: July 2007

Testosterone promotes aggressive behaviour in male vertebrates during the breeding season, but the importance of testosterone in female aggression remains unclear. Testosterone has both beneficial and detrimental effects on behaviour and physiology, prompting the hypothesis that selection favours an association between aggression and testosterone only in certain contexts in which intense or persistent aggression may be beneficial. We tested this hypothesis in a year-round territorial female buff-breasted wrens (
Thryothorus leucotis
), by exposing free-living females to experimental intrusions in different social (either single female or male, or paired decoys) and seasonal (pre-breeding or breeding) contexts. Females responded more aggressively to intrusions by females and pairs than to males. However, female intrusions elicited stronger responses during pre-breeding, whereas responses to pair intrusions were more intense during breeding. Territorial females had elevated testosterone levels after female intrusions and intermediate levels after pair intrusions during pre-breeding, but the levels of testosterone remained low after these intrusions during breeding. These results demonstrate seasonal differences in circulating testosterone following territorial aggression in female buff-breasted wrens and are suggestive of differences according to social context as well. Context-dependent elevation of testosterone implies that selection acts directly on female vertebrates to shape patterns of testosterone secretion.
The smell of parents: breeding status influences cuticular hydrocarbon pattern in the burying beetle
Nicrophorus vespilloides
Authors: Steiger Sandra , Peschke Klaus , Francke Wittko , Müller Josef K
Published: July 2007

The waxy layer of the cuticle has been shown to play a fundamental role in recognition systems of insects. The biparental burying beetle
Nicrophorus vespilloides
is known to have the ability to discriminate between breeding and non-breeding conspecifics and also here cuticular substances could function as recognition cue. However, it has not yet been demonstrated that the pattern of cuticular lipids can reflect the breeding status of a beetle or of any other insect. With chemical analysis using coupled gas chromatography–mass spectrometry, we showed that the chemical signature of
N. vespilloides
males and females is highly complex and changes its feature with breeding status. Parental beetles were characterized by a higher amount of some unusual unsaturated hydrocarbons than beetles which are not caring for larvae. The striking correlation between cuticular profiles and breeding status suggests that cuticular hydrocarbons inform the beetles about parental state and thus enable them to discriminate between their breeding partner and a conspecific intruder. Furthermore, we found evidence that nutritional conditions also influence the cuticular profile and discuss the possibility that the diet provides the precursors for the unsaturated hydrocarbons observed in parental beetles. Our study underlines the fact that the cuticular pattern is rich of information and plays a central role in the burying beetles' communication systems.
Characterisation of a large complex intragenic re‐arrangement in the FVII gene (F7) avoiding misdiagnosis in inherited factor VII deficiency
Authors: Giansily‐Blaizot Muriel , Thorel Delphine , Khau Van Kien Philippe , Behar Catherine , Romey Marie‐Catherine , Mugneret Francine , Schved Jean‐François , Claustres Mireille
Published: July 2007

Inherited factor VII (FVII) deficiency is a rare autosomal recessive bleeding disorder mostly caused by point mutations. Large genomic re‐arrangements at F7 locus could account for a fraction of mutant alleles that remain unidentified after DNA sequencing, because they escape conventional polymerase chain reaction (PCR)‐based techniques. We report the first systematic screening of F7 for large re‐arrangements, by semi‐quantitative multiplex PCR of fluorescent fragments targeting the 9 exons and the promoter region. A well‐characterised cohort of 43 unrelated patients either apparently homozygous for a F7 point mutation or carrying at least one unidentified F7 mutant allele participated in this study. Two large F7 re‐arrangements were identified in two FVII‐deficient pedigrees, including a discontinuous deletion involving two distinct portions of F7 whose proximal and distal end junctions were characterised. A simple and efficient method for the routine detection of gross alterations of F7, which accounted for 2.3% of mutant alleles in our sample, is now available in inherited FVII deficiency. This test should complement conventional PCR‐based techniques not only in unsolved cases, but also where inheritance pattern analysis is not achievable.