bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhancement of drain current density by inserting 3nm Al layer in the gate of AlGaN∕GaN high-electron-mobility transistors on 4in. silicon
Authors: Selvaraj S. Lawrence , Egawa Takashi
Published: November 2006

Al Ga N ∕ Ga N high-electron-mobility transistors (HEMTs) on 4in. Si were fabricated by inserting 3nm of Al metal as a gate prior to the deposition of Pd∕Ti∕Au. The increase of drain current (IDSmax) density and decrease of extrinsic transconductance (gmmax) have been observed in the Al-gated AlGaN∕GaN HEMTs. The increase of IDmax is due to the increase of two-dimensional electron gas sheet carrier density, which was confirmed by capacitance-voltage (C-V) measurements. Moreover, the Al layer inserted-gate HEMT exhibited negative threshold voltage (Vth) shift. The Al and AlGaN interface shows Al-based oxide layer which was confirmed by Auger electron spectrum and x-ray photoelectron spectrum.
Effect of quantum confinement on higher transitions in HgTe nanocrystals
Authors: Rinnerbauer Veronika , Hingerl Kurt , Kovalenko Maksym , Heiss Wolfgang
Published: November 2006

Spectroscopic ellipsometry measurements on 1–10 bilayers of HgTe nanocrystals and polymer were performed in the spectral range from 0.5to5eV. The experiments show that the band model, respectively, band energy shifts due to quantization, can be applied onto nanocrystals with as few as five unit cells in diameter. These nanocrystals exhibit strong transitions at higher critical points. The critical point energies shift up to 0.4eV. It turns out that transitions between bands which are closer to the Fermi energy and have a smaller carrier mass are more strongly affected by quantum confinement.
Anisotropy of transient photoconductivity in functionalized pentacene single crystals
Authors: Ostroverkhova O. , Cooke D. G. , Hegmann F. A. , Tykwinski R. R. , Parkin S. R. , Anthony J. E.
Published: November 2006

We report on the anisotropy of transient photoconductivity in functionalized pentacene single crystals using ultrafast optical pump–terahertz probe techniques. Functionalized pentacene crystals with tri-isopropylsilylethynyl (TIPS) and tri-ethylsilylethynyl (TES) side groups were studied, characterized by crystal structures favoring two-dimensional and one-dimensional charge transports, respectively. Charge carrier mobility anisotropies in the a-b plane of 3.5±0.6 and 12±6 were obtained in the TIPS and TES crystals, respectively, consistent with the degree of π overlap along different directions in the crystals. A photogeneration efficiency anisotropy was also observed in both types of crystals.
Deformation of multiwalled nanometer-sized carbon capsules
Authors: Asaka Koji , Kato Ryoei , Miyazawa Kun’ichi , Kizuka Tokushi
Published: November 2006

The deformation of isolated multiwalled carbon capsules of a few nanometers in diameter was observed by in situ transmission electron microscopy with simultaneous force measurement by means of an optical cantilever method as used in atomic force microscopy. The mechanical properties of the carbon nanocapsules were investigated on an atomic scale. A carbon nanocapsule of 2.50±0.06nm in diameter was selected and compressed upto a strain of 0.06 at a force of up to 4.5±0.5nN using a nanometer-sized gold tip of a microcantilever. By subsequent retraction, we measured the force between the carbon nanocapsule and the gold tip, and assessed the adhesion.
In situ mass measurement of electron-beam-induced nanometer-sized W-related deposits using a carbon nanotube cantilever
Authors: Sawaya Shintaro , Akita Seiji , Nakayama Yoshikazu
Published: November 2006

Using a carbon nanotube oscillator, the authors performed in situ measurements of densities of electron-beam-induced tungsten compounds with size of less than 100nm. Total mass of the deposit was proportional to the deposition time. A higher deposition rate was obtained at lower electron-beam acceleration voltage. Density of the deposit decreased from 2.7to1.4g∕cm3 with increasing acceleration voltage from 5to15kV. These results indicate that the increased density with low-acceleration voltage produces effective decomposition of W(CO)6.
Band anticrossing in InGaPN alloys induced by N-related localized states
Authors: Lin K. I. , Hwang J. S.
Published: November 2006

Temperature-dependent photoreflectance measurements are employed to characterize the electronic band structure of InGaPN grown on GaAs substrates. In addition to the fundamental band gap, the upper subband E+ is observed as predicted by the band anticrossing (BAC) model. By eliminating the contributions of the epitaxial-strain and atomic-ordering effects in InGaPN and also assigning the localized state energy EN introduced by an isolated N to be 2.040eV at 293K, the interaction potential V is determined as 1.449±0.170eV. The incorporation of a temperature-dependent EN level into the BAC model fits the experimental data better than assuming EN to be a constant. This contrasts with previously published results and so provides a different view of the temperature dependence of the EN level in InGaPN.
Recurrent duplication-driven transposition of DNA during hominoid evolution
Authors: Johnson Matthew E. ,   NISC Comparative Sequencing Program, Cheng Ze , Morrison V. Anne , Scherer Steven , Ventura Mario , Gibbs Richard A. , Green Eric D. , Eichler Evan E.
Published: November 2006

The underlying mechanism by which the interspersed pattern of human segmental duplications has evolved is unknown. Based on a comparative analysis of primate genomes, we show that a particular segmental duplication (LCR16a) has been the source locus for the formation of the majority of intrachromosomal duplications blocks on human chromosome 16. We provide evidence that this particular segment has been active independently in each great ape and human lineage at different points during evolution. Euchromatic sequence that flanks sites of LCR16a integration are frequently lineage-specific duplications. This process has mobilized duplication blocks (15–200 kb in size) to new genomic locations in each species. Breakpoint analysis of lineage-specific insertions suggests coordinated deletion of repeat-rich DNA at the target site, in some cases deleting genes in that species. Our data support a model of duplication where the probability that a segment of DNA becomes duplicated is determined by its proximity to core duplicons, such as LCR16a.
Translating the Self: Language and Identity in Iranian-American Women's Memoirs
Authors: Elahi Babak
Published: November 2006

In recent years, a number of Iranian American women have written and published memoirs of a return to Iran. One motif that these memoirs share is their concern with language as a key element of cultural identity. The article examines these memoirs as negotiations of identity through language. Relying on Joshua Fishman's anthropological definition of language and ethnicity as being, doing, and knowing, and on Taghi Modarressi's notion of “accented writing,” this article examines these writers in terms of their relationship to Persian as a key component of the self. As these memoirists narrate their journeys between Iran and the United States, they perform a translation of self across the boundaries of language. Some narrate an “accented identity” that celebrates hybridity; others acknowledge their assimilation into American society and into the English language. All attempt to reclaim Persian as an artifact, if not a medium of cultural belonging.
Kiarostami and the Aesthetics of Modern Persian Poetry
Authors: Sheibani Khatereh
Published: November 2006

Abbas Kiarostami's filmmaking draws on the aesthetics of modern Persian poetry, especially the poetry of Forough Farrokhzad and Sohrab Sepehri. In his films, Kiarostami, impacted by Sepehri and Farrokhzad's “de-politicized” poetry, “de-experiences” our perception of reality. Kiarostami aestheticizes everyday life by employing non-manipulative film stylistics. In films such as Through the Olive Trees and Where Is the Friend's House? he uses a minimalist approach by employing amateur actors and children, depth of field, and minimal camera work to enhance Sepehri's philosophy of novel outlook. Through a masterful intermingling of poetic discourse with his film sensibilities, Kiarostami has achieved a profoundly humanist approach to cinema. Kiarostami mixes the two genres of documentary and fiction to remind the audience of the artificiality of constructing a factual point. To attain this goal, he sometimes uses an ironical and witty cinematic language that is harshly self-critical and self-reflexive. Kiarostami is a poet/philosopher who “writes” his poetic films with camera.
Communications, Qajar Irredentism and the Strategies of British India: The Makran Coast Telegraph and British Policy of Containing Persia in the East (Baluchistan)—Part II
Authors: Shahvar Soli
Published: November 2006

Persian territorial designs in Baluchistan clashed with British interest to construct an Indo-European telegraph line through the Makran Coast, where Britain had close local allies in dispute with Persia. The British prime interest being the speedy construction of the line, they decided on bypassing these disputed territories by connecting Bushehr, through submarine cable, with Gwadar—which they believed, contrary to the Persians, to be non-Persian. The Persian government protested against the British infringement of her sovereign rights, adopting both diplomatic and military approaches. This forced the British government to check the legality of the Persian claims. But the arbitrary was neither neutral nor fair, with Britain opposing the suzerainty of Persia over the chiefs of western Makran, while acknowledging the right of conquest by others elsewhere on the coast. This was in line with British policy of favoring governments bordering British India over Persia. Although unable to change the arbitrary, the Persian government still managed, in spite of her military weakness, to drag the British government into a hard bargain and tough negotiations.
Regional Political Divisions in Ukraine in 1991–2006
Authors: Katchanovski Ivan
Published: November 2006

This article examines determinants of persistent regional political cleavages in post-Communist Ukraine. The question is how significant the role of culture is compared to ethnic, economic, and religious factors in the regional divisions. This study employs correlation, factor, and regression analyses of regional support for the Communist/pro-Russian parties and presidential candidates and pro-nationalist/pro-independence parties and candidates in all national elections held from 1991 to 2006, the vote for the preservation of the Soviet Union in the March 1991 referendum, and the vote for the independence of Ukraine in the December 1991 referendum. This study shows that the pattern of these regional differences remained relatively stable from 1991 to 2006. Historical experience has a major effect on regional electoral behavior in post-Communist Ukraine. The legacy of Austro-Hungarian, Polish, Romanian, and Czechoslovak rule is positively associated with the pro-nationalist and pro-independence vote; the same historical legacy has a negative effect on support for pro-Communist and pro-Russian parties and presidential candidates and on the vote for the preservation of the Soviet Union.
Redefining Religion: Uzbek Atheist Propaganda in Gorbachev-Era Uzbekistan
Authors: Kendzior Sarah
Published: November 2006

Much has been made in the social sciences of the ambiguity of nationalism in Central Asia, where not only the boundaries between republics but between nations, languages, and peoples were drawn by the Soviet state. The similar ambiguity of Central Asian religiosity, however, has remained largely ignored. Perhaps religiosity, unlike the more recent idea of nationalism, is considered too fixed a construct for the modern and artificially created states of Central Asia. The division of religions into specific sects, each with its own explicit doctrine and precepts, would seem to preclude definitional necessity. Yet in the 1980s it was religiosity, malleable and stubborn, which proved as essential to the decline of the Soviet Union as did nationalism. As a vital component of identity, religion can exist without any clergy, place of worship, or understanding of sacred text, much as a nation can exist without a state or a government. The illusory aspects of religion, the comforts and mystery of rite and ritual, are as difficult for a state to control as national sentiment, and often prove the impetus behind the latter.
Competing Priorities, Ambiguous Loyalties: Challenges of Socioeconomic Adaptation and National Inclusion of the Interwar Bulgarian Refugees
Authors: Dragostinova Theodora
Published: November 2006

From the estimated ten million refugees in interwar Europe, more than 250,000 were ethnic Bulgarians who found their way in the Bulgarian Kingdom following Bulgarian defeats in the Second Balkan War and World War One. For a country with a population of five and a half million in the mid-1920s, this refugee flow constituted a significant challenge from economic, political, social, and cultural viewpoints. Similarly to Germany, Hungary, and Austria, the refugee presence served as a constant reminder of national failure because Bulgaria lost territories, perceived as a part of the national homeland, to all of its neighbors. The Bulgarian state received refugees from the Ottoman Empire, Greece, Yugoslavia, and Romania, and the interwar governments were compelled to deal with a large and diverse population that suffered harsh socioeconomic problems and psychological traumas. Due to the Convention for Emigration of Minorities between Greece and Bulgaria of 1919 as well as the Greek-Turkish War of 1921–1922 and the obligatory population exchange it initiated in the period 1922–1924, refugee flows in the Balkans lasted well into the mid-1920s. Hence Bulgarians were on the move throughout 1924 and 1925. Despite these strenuous circumstances, interwar politicians boasted the successful integration of the refugees. Immediately after World War One, the government provided temporary assistance to the newcomers. In 1926, an international loan allowed the agricultural settlement of the most destitute new arrivals, and all refugees were granted the rights of Bulgarian citizens. A second loan in 1928 guaranteed the continuation of vital infrastructure projects. By the end of the 1930s, both domestic and international agencies involved in the refugee accommodation viewed the process as a successfully completed mission.
The Development and Institutionalization of Romani Representation and Administration. Part 3a: From National Organizations to International Umbrellas (1945–1970)—Romani Mobilization at the National Level
Authors: Klímová-Alexander Ilona
Published: November 2006

This article is the third in this Nationalities Papers series, following “Part 1: The Legacy of Early Institutionalism: From Gypsy Fiefs to Gypsy Kings,” which covered the period from the arrival of Gypsies to Europe until the mid-nineteenth century (Vol. 32, No. 3), and “Part 2: Beginnings of Modern Institutionalization,” describing the birth of the first modern forms of ethnically-based political and social organizations established by Romani elites from the nineteenth century up until the Second World War (WWII) (Vol. 33, No. 2). The article concentrates on developments between two significant landmarks in the history of Romani mobilization—the end of WWII in 1945 and the institutionalization of a permanent international Romani body in the form of a World Romani Congress, held for the first time in 1971. The time period covered in this article is distinguished from the previously covered periods by the emergence of the following phenomena: (1) modern Romani political organizations at the national level, (2) their unification through international Romani umbrella organizations, (3) some limited Romani participation in non-Romani mainstream political or administrative structures, (4) an international Romani evangelical movement, (5) reconciliation between Romani political representation and the Catholic Church, (6) national institutions created by various governments to aid the administration of policies on Roma, (7) rapid growth of non-governmental organizations addressing Romani issues, and (8) some limited cooperation between Romani organizations and intergovernmental organizations.
Questioning the Hegemony of the Nation State in Belarus: Production of Intellectual Discourses as Production of Resources
Authors: Pershai Alexander
Published: November 2006

Katherine Verdery writes that “[i]n the modern period, nation has become a potent symbol and basis of classification within an international system of nation states”; in turn, nationalism “is a political utilization of the symbol nation through discourse and political activity, as well as the sentiment that draws people into responding to this symbol's use.” However, the idea of “nation state” and its functioning can be seen as a part of the larger hegemonic constructions that operate on the level of “common” beliefs that legitimize existing social hierarchies and divisions of economic resources, and on the level of relationships between states and nations.
Reinventing grounded theory: some questions about theory, ground and discovery
Authors: Thomas Gary , James David
Published: November 2006

Grounded theory's popularity persists after three decades of broad‐ranging critique. In this article three problematic notions are discussed—‘theory,’ ‘ground’ and ‘discovery’—which linger in the continuing use and development of grounded theory procedures. It is argued that far from providing the epistemic security promised by grounded theory, these notions—embodied in continuing reinventions of grounded theory—constrain and distort qualitative inquiry, and that what is contrived is not in fact theory in any meaningful sense, that ‘ground’ is a misnomer when talking about interpretation and that what ultimately materializes following grounded theory procedures is less like discovery and more akin to invention. The procedures admittedly provide signposts for qualitative inquirers, but educational researchers should be wary, for the significance of interpretation, narrative and reflection can be undermined in the procedures of grounded theory.
What counts as evidence in the school choice debate?
Authors: Gorard Stephen , Fitz John
Published: November 2006

This article has two chief purposes. It presents a substantive reappraisal of a decade of school choice research in the UK. This reappraisal is used as a case study illustrating the elasticity of the notion of social science ‘evidence’, when wielded by academics in an area where strong ideological preconceptions struggle with the lack of a sound quantitative tradition of research. The focus here is on the changing socio‐economic compositions of schools in an era of choice. A prediction from theory and from small‐scale studies had been that schools in England and Wales would become more segregated in terms of indicators of socio‐economic disadvantage after the Education Reform Act 1988. The first large‐scale study of the actual compositions of schools suggested that this did not happen. This study was then subjected by a majority of UK academics in the field to a level of criticism that was not applied by them to subsequent, but seemingly inferior, studies that reached an opposite conclusion. The criticism involved widespread misquotation and misunderstanding that was not picked up by ‘peer’ review. What, therefore, counts as evidence in the school choice debate?
Measuring standards in primary English: issues of validity and accountability with respect to PIRLS and National Curriculum test scores
Authors: Hilton Mary
Published: November 2006

This article revisits the important issue raised by Peter Tymms where he challenges the official government reports of an impressive rise in standards in mathematics and English in primary schools in England since 1995, suggesting that the rise in scores, particularly since 2000, does not indicate rising standards. In order to substantiate its claim the Government has repeatedly referred to the results of an international study which put England in the top three of the 35 participating countries for achievement in reading, the Progress in International Reading Literacy Study (2001). Firstly, the nature of an international comparison which uses a single indicator of achievement is critically examined in terms of the fair comparison and resulting commensurability of very different national school populations. Here issues of cultural bias are raised in relation to the unidimensionality of the reading test items and the contrasting wealth, representational sizes, and varied geographic dispersals of the target populations. Secondly, the PIRLS study is analysed for its potential for linguistic bias. Finally, the PIRLS data for England are examined, where it is shown, in comparison with other countries, the sampling and the test itself to have been advantageously organised. The article concludes with a critical discussion of the validity of known results with regard to the testing of English primary‐aged children in literacy.
Phosphodiesterase-5 inhibition augments endogenous antitumor immunity by reducing myeloid-derived suppressor cell function
Authors: Serafini Paolo , Meckel Kristen , Kelso Michael , Noonan Kimberly , Califano Joseph , Koch Wayne , Dolcetti Luigi , Bronte Vincenzo , Borrello Ivan
Published: November 2006

Phosphodiesterase-5 (PDE5) inhibitors (sildenafil, tadalafil, and vardenafil) are agents currently in clinical use for nonmalignant conditions. We report the use of PDE5 inhibitors as modulators of the antitumor immune response. In several mouse tumor models, PDE5 inhibition reverses tumor-induced immunosuppressive mechanisms and enables a measurable antitumor immune response to be generated that substantially delays tumor progression. In particular, sildenafil, down-regulates arginase 1 and nitric oxide synthase–2 expression, thereby reducing the suppressive machinery of CD11b+/Gr-1+ myeloid-derived suppressor cells (MDSCs) recruited by growing tumors. By removing these tumor escape mechanisms, sildenafil enhances intratumoral T cell infiltration and activation, reduces tumor outgrowth, and improves the antitumor efficacy of adoptive T cell therapy. Sildenafil also restores in vitro T cell proliferation of peripheral blood mononuclear cells from multiple myeloma and head and neck cancer patients. In light of the recent data that enzymes mediating MDSC-dependent immunosuppression in mice are active also in humans, these findings demonstrate a potentially novel use of PDE5 inhibitors as adjuncts to tumor-specific immune therapy.
Evidence for an elementary process in bone plasticity with an activation enthalpy of 1 eV
Authors: Gupta Himadri S , Fratzl Peter , Kerschnitzki Michael , Benecke Gunthard , Wagermaier Wolfgang , Kirchner Helmut O.K
Published: November 2006

The molecular mechanisms for plastic deformation of bone tissue are not well understood. We analysed temperature and strain-rate dependence of the tensile deformation behaviour in fibrolamellar bone, using a technique originally developed for studying plastic deformation in metals. We show that, beyond the elastic regime, bone is highly strain-rate sensitive, with an activation volume of
ca
0.6 nm
3
. We find an activation energy of 1.1 eV associated with the basic step involved in the plastic deformation of bone at the molecular level. This is much higher than the energy of hydrogen bonds, but it is lower than the energy required for breaking covalent bonds inside the collagen fibrils. Based on the magnitude of these quantities, we speculate that disruption of electrostatic bonds between polyelectrolyte molecules in the extrafibrillar matrix of bone, perhaps mediated by polyvalent ions such as calcium, may be the rate-limiting elementary step in bone plasticity.
Explaining a complex living system: dynamics, multi-scaling and emergence
Authors: Cohen Irun R , Harel David
Published: November 2006

Complex living systems are difficult to understand. They obey the laws of physics and chemistry, but these basic laws do not explain their behaviour; each component part of a complex system participates in many different interactions and these interactions generate unforeseeable, emergent properties. For example, microscopic interactions between non-living molecules, at the macroscopic level, produce a living cell. Here we discuss how to explain such complexity in the format of a dynamic model that is mathematically precise, yet understandable. Precise, computer-aided modelling will make it easier to formulate novel experiments and attain understanding and control of key biological processes.
On the commutative factorization of
n
×
n
matrix Wiener–Hopf kernels with distinct eigenvalues
Authors: Veitch Benjamin H , David Abrahams I
Published: November 2006

In this article, we present a method for factorizing
n
×
n
matrix Wiener–Hopf kernels where
n
>2 and the factors commute. We are motivated by a method posed by Jones (Jones 1984
a Proc. R. Soc. A
393
, 185–192) to tackle a narrower class of matrix kernels; however, no matrix of Jones' form has yet been found to arise in physical Wiener–Hopf models. In contrast, the technique proposed herein should find broad application. To illustrate the approach, we consider a 3×3 matrix kernel arising in a problem from elastostatics. While this kernel is not of Jones' form, we shall show how it can be factorized commutatively. We discuss the essential difference between our method and that of Jones and explain why our method is a generalization.

The majority of Wiener–Hopf kernels that occur in canonical diffraction problems are, however, strictly non-commutative. For 2×2 matrices, Abrahams has shown that one can overcome this difficulty using Padé approximants to rearrange a non-commutative kernel into a partial-commutative form; an approximate factorization can then be derived. By considering the dynamic analogue of Antipov's model, we show for the first time that Abrahams' Padé approximant method can also be employed within a 3×3 commutative matrix form.
Sperm competition games: optimal sperm allocation in response to the size of competing ejaculates
Authors: Engqvist Leif , Reinhold Klaus
Published: November 2006

Sperm competition theory predicts that when males are certain of sperm competition, they should decrease sperm investment in matings with an increasing number of competing ejaculates. How males should allocate sperm when competing with differently sized ejaculates, however, has not yet been examined. Here, we report the outcomes of two models assuming variation in males' sperm reserves and males being faced with different amounts of competing sperm. In the first ‘spawning model’, two males compete instantaneously and both are able to assess the sperm competitive ability of each other. In the second ‘sperm storage model’, males are sequentially confronted with situations involving different levels of sperm competition, for instance different amounts of sperm already stored by the female mating partner. In both of the models, we found that optimal sperm allocation will strongly depend on the size of the male's sperm reserve. Males should always invest maximally in competition with other males that are equally strong competitors. That is, for males with small sperm reserves, our model predicts a negative correlation between sperm allocation and sperm competition intensity, whereas for males with large sperm reserves, this correlation is predicted to be positive.
Song discrimination learning in zebra finches induces highly divergent responses to novel songs
Authors: Verzijden Machteld N , Etman Eric , van Heijningen Caroline , van der Linden Marianne , ten Cate Carel
Published: November 2006

Perceptual biases can shape the evolution of signal form. Understanding the origin and direction of such biases is therefore crucial for understanding signal evolution. Many animals learn about species-specific signals. Discrimination learning using simple stimuli varying in one dimension (e.g. amplitude, wavelength) can result in perceptual biases with preferences for specific novel stimuli, depending on the stimulus dimensions. We examine how this translates to discrimination learning involving complex communication signals; birdsongs. Zebra finches (
Taeniopygia guttata
) were trained to discriminate between two artificial songs, using a Go/No-Go procedure. The training songs in experiment 1 differed in the number of repeats of a particular element. The songs in experiment 2 differed in the position of an odd element in a series of repeated elements. We examined generalization patterns by presenting novel songs with more or fewer repeated elements (experiment 1), or with the odd element earlier or later in the repeated element sequence (experiment 2). Control birds were trained with only one song. The generalization curves obtained from (i) control birds, (ii) experimental birds in experiment 1, and (iii) experimental birds in experiment 2 showed large and systematic differences from each other. Birds in experiment 1, but not 2, responded more strongly to specific novel songs than to training songs, showing ‘peak shift’. The outcome indicates that learning about communication signals may give rise to perceptual biases that may drive signal evolution.
The cost of replication fidelity in human immunodeficiency virus type 1
Authors: Furió Victoria , Moya Andrés , Sanjuán Rafael
Published: November 2006

Mutation rates should be governed by at least three evolutionary factors: the need for beneficial mutations, the benefit of minimizing the mutational load and the cost of replication fidelity. RNA viruses show high mutation rates compared with DNA micro-organisms, and recent findings suggest that the cost of fidelity might play a role in the evolution of increased mutation rates. Here, by analysing previously published data from HIV-1 reverse transcriptase
in vitro
assays, we show a trade-off between enzymatic accuracy and the maximum rate of polymerization, thus providing a biochemical basis for the fitness cost of fidelity in HIV-1. This trade-off seems to be related to inefficient extension of mispairs, which increases fidelity at the expense of the polymerization rate. Since in RNA viruses fast replication is critical for survival, this could impose a high cost of fidelity and favour the evolution of high mutation rates.
Social personalities influence natal dispersal in a lizard
Authors: Cote J , Clobert J
Published: November 2006

Animal personalities are common across taxa and have important evolutionary and ecological implications. Such consistent individual differences correlate with important life-history traits such as dispersal. Indeed, some environmental conditions are supposed to determine dispersers with a specific personality. For example, an increased density should promote the departure of individuals with less social tolerance. Therefore, we hypothesized that dispersers from high-density populations should primarily be asocial individuals, whereas dispersers from low-density populations should be social individuals. In the common lizard (Lacerta vivipara), we measured attraction towards the odour of conspecifics on juveniles at birth as a metric of social tolerance. We then released these juveniles into populations of different densities and measured dispersal and settlement behaviours with regard to social tolerance. One year later, we again measured the social tolerance of surviving individuals. The social tolerance is constant across time and strongly reflects the individual's dispersal and settlement patterns with respect to population density. These results strongly suggest that social personalities exist and influence dispersal decisions. Further studies will help to elucidate the proximate and ultimate determinants of social personalities.
Association analysis of adiponectin and somatostatin polymorphisms on BTA1 with growth and carcass traits in Angus cattle
Authors: Morsci N. S. , Schnabel R. D. , Taylor J. F.
Published: November 2006

This study tested positional candidate genes adiponectin (ADIPOQ) and somatostatin (SST) for effects on carcass traits in a commercially relevant cattle population. Both genes are located within a region of BTA1 previously reported to harbour quantitative trait loci (QTL) that affect marbling, quality grade, yield grade, ribeye area and weaning weight in Bos taurus × Bos indicus crosses. Except for the first intron of ADIPOQ, both genes, including over 2 kb upstream of the promoters, were sequenced in five registered Angus sires to identify polymorphisms. A variable copy duplication and three single nucleotide polymorphisms (SNPs) in ADIPOQ and one SNP in SST were genotyped and tested for association with 19 traits in a 14‐generation pedigree of 1697 registered Angus artificial insemination sires representing all the major USA lineages of the breed. Linear models that parameterized predicted genetic merits in terms of allele substitution effects were fit by weighted least squares, and goodness‐of‐fit tests were employed to differentiate causal mutations or polymorphisms in strong linkage disequilibrium (LD) with causal mutations from markers in weak LD with QTL. We confirmed the presence of QTL affecting marbling, ribeye muscle area and fat thickness in the vicinity of SST and ADIPOQ on BTA1 in Angus; excluded SST as underlying the ribeye muscle area QTL; and excluded ADIPOQ as underlying the marbling score QTL. However, association analysis provides very limited information about QTL location and has little intrinsic value when performed in the absence of linkage or LD analysis using flanking marker data to localize the QTL effect relative to positional candidate genes.
Rivaroxaban (BAY 59‐7939) – an oral, direct Factor Xa inhibitor – has no clinically relevant interaction with naproxen
Authors: Kubitza Dagmar , Becka Michael , Mueck Wolfgang , Zuehlsdorf Michael
Published: November 2006

What is already known about this subject

• Rivaroxaban is a novel anticoagulant with predictable, dose‐proportional pharmacokinetics and pharmacodynamics in healthy subjects.

• It is in clinical development for the prevention of thromboembolic disorders in patients undergoing major orthopaedic surgery.

• Nonsteroidal anti‐inflammatory drugs (NSAIDs), such as naproxen, are widely used for pain relief and treatment of inflammation, particularly in patients who have undergone orthopaedic surgery. As it is likely that patients receiving rivaroxaban after orthopaedic surgery will also receive NSAIDs, this study was performed to determine whether there was any mechanistic interaction between rivaroxaban and naproxen.

What this study adds

• This study demonstrated that there was no mechanistic interaction between rivaroxaban and naproxen in healthy subjects.

• This finding was used to design large‐scale clinical trials of rivaroxaban, in which patients were also allowed to use NSAIDs.

• These ongoing trials will provide definitive data regarding the interaction between rivaroxaban and NSAIDs.

Aims

Rivaroxaban (BAY 59‐7939) is in advanced clinical development for the prevention and treatment of thromboembolic disorders. Frequent co‐medications in the patient populations likely to receive rivaroxaban include NSAIDs. This randomized, two‐way crossover study, with a naproxen run‐in period, was performed to determine whether naproxen influences the tolerability, pharmacodynamics and pharmacokinetics of rivaroxaban.

Methods

Eleven healthy, young males received naproxen 500 mg on two consecutive days, a single dose of rivaroxaban 15 mg, or both.

Results

Treatments were well tolerated: adverse events (eight in total), reported by three subjects, were mild and not drug related. Rivaroxaban inhibited Factor Xa activity by 35% and prolonged prothrombin time [by 1.4 times baseline (tb)], activated partial thromboplastin time (1.3 tb) and the HepTest (1.9 tb). Naproxen had no influence on these measures and the combination of rivaroxaban and naproxen did not affect platelet aggregation. Rivaroxaban and naproxen given together significantly increased bleeding time compared with rivaroxaban alone (P = 0.017). However, this difference was small compared with the effect of naproxen given alone, except in one subject. Least squares‐means ratios for the AUC and Cmax of rivaroxaban after administration alone and with naproxen were 1.125 [90% confidence interval (CI) 0.995, 1.271] and 1.095 (90% CI 0.905, 1.325), respectively.

Conclusions

There appeared to be no clinically relevant interaction between rivaroxaban and naproxen in healthy subjects, although some individuals may be more sensitive to the combination. Large‐scale Phase III clinical studies will be required to confirm whether there is an increased risk of bleeding during treatment with rivaroxaban and concomitant NSAIDs.
Mechanism of interleukin‐25 (IL‐17E)‐induced pulmonary inflammation and airways hyper‐reactivity
Authors: Sharkhuu T. , Matthaei K. I. , Forbes E. , Mahalingam S. , Hogan S. P. , Hansbro P. M. , Foster P. S.
Published: November 2006

Background
IL‐25, a novel member of the IL‐17 cytokine family, promotes CD4+ T‐helper 2 lymphocyte‐like (Th type‐2) inflammatory responses in the lung. Although IL‐25 up‐regulates IL‐13 in the lung, the contribution of this and other type 2 cytokine signalling pathways to the induction and persistence of airways hyper‐reactivity (AHR) and allergic inflammation are unclear.

Objective
To determine the downstream factors employed by IL‐25 to induce Th type‐2 pulmonary inflammation and AHR.

Methods
IL‐25 was delivered to the airways of BALB/c mice by intra‐tracheal (i.t.) instillation and AHR and Th type‐2 inflammatory responses were characterized in wild type (WT) and Th type‐2‐cytokine and ‐signalling pathway‐deficient (−/−) mice.

Results
IL‐25 treatment resulted in AHR, eosinophilic inflammation, mucus hypersecretion and a progressive increase in the production of Th type‐2 cytokines in the lungs. Levels of arginase‐I (arg‐I) and eotaxin were also elevated by IL‐25 treatment. A significant reduction in AHR, and attenuation of mucus production was observed in IL‐25‐treated IL‐13−/−, IL‐4 receptor alpha (IL‐4Rα−/−)‐ and signal‐transducer‐and‐activator‐of‐transcription‐factor‐6 (STAT6−/−)‐deficient mice. AHR was also inhibited in IL‐4−/−‐ and IL‐5/eotaxin(1)−/−‐ deficient mice treated with IL‐25, however, mucus hypersecretion was not completely ablated. IL‐25 promoted Th type‐2 responses by directly acting on naïve T cells.

Conclusion
IL‐25 potently (single dose) induces sustained AHR and acute pulmonary inflammation with eosinophilia. IL‐25‐induced AHR is dependent on the production of Th type‐2 cytokines, and removal of IL‐13 and its signal transduction pathway prevents IL‐25‐induced airways inflammation and AHR. IL‐25 potently induces inflammatory cascades that may exacerbate allergic airways inflammation by promoting Th type‐2 cytokine responses in conjunction with the up‐regulation of factors (eotaxin and arg‐I) that can amplify inflammation associated with allergic disorders. Dysregulation in IL‐25 production may predispose to features of allergic airways disease.
Conservation of the vaquita Phocoena sinus
Authors: ROJAS‐BRACHO LORENZO , REEVES RANDALL R. , JARAMILLO‐LEGORRETA ARMANDO
Published: November 2006

The vaquita Phocoena sinus is a small porpoise that is endemic to the northern Gulf of California, Mexico. It is the most critically endangered marine small cetacean in the world. The most precise estimate of global abundance based on a 1997 survey is 567 (95% CI 177–1073).

Vaquitas mainly live north of 30°45′N and west of 114°20′W. Their ‘core area’ consists of about 2235 km2 centred around Rocas Consag, 40 km east of San Felipe, Baja California. Genetic analyses and population simulations suggest that the vaquita has always been rare, and that its extreme loss of genomic variability occurred over evolutionary time rather than being caused by human activities.

Gill nets for fish and shrimp cause very high rates of by‐catch (entanglement) of vaquitas. Estimates of bycatch rates are from 1993–94 and refer to one of three main fishing ports: 84 per year (95% CI 14–155) using only data collected by observers and 39 per year (95% CI 14–93) using combined data from observers and interviews with fishermen. Boats from other ports may experience similar rates, and the total is probably well above what would be sustainable.

Other less well‐characterized and longer‐term risk factors include the potential for disturbance by trawling to affect vaquita behaviour, and the uncertain effects of dam construction on the Colorado River and the resultant loss of freshwater input to the upper Gulf. However, entanglement is the clearest and most immediate concern.

Progress towards reducing entanglement has been slow in spite of efforts to phase out gill nets in the vaquita’s core range, and the development of schemes involving compensation for fishermen. The Biosphere Reserve in the northern Gulf has fallen far short of its potential for vaquita conservation. On 29 December 2005, the Mexican Ministry of Environment declared a Vaquita Refuge that contains within its borders the positions of approximately 80% of verified vaquita sightings. In the same decree, the state governments of Sonora and Baja California were offered $1 million to compensate affected fishermen. The effectiveness of this major initiative remains to be seen.

The vaquita’s survival does not depend on more or better science but on improved management. As a funding priority, implementation of conservation measures and evaluation of their effectiveness should come ahead of more surveys or improved estimation of by‐catch.
Estimating red deer Cervus elaphus populations: an analysis of variation and cost‐effectiveness of counting methods
Authors: DANIELS MIKE J.
Published: November 2006

Different counting methods are currently used to estimate red deer populations in the open range in Scotland, but there are few data available to compare variation in estimates, or relative cost‐effectiveness.

While it is impossible to determine the accuracy of counts (as real numbers are unknown), variation within and between different methods can be measured by repeat counts of the same area within as short a period as possible.

This study aimed to quantify the variation observed from repeat counts using each of four methods (ground, helicopter, infrared helicopter and dung‐counting methods) at one of three study sites in late winters 2003, 2004 and 2005. Additional data from digital camera images of groups from counts in other areas of Scotland were also used to assess the accuracy of visual counts.

Coefficients of variation (CVs) within any method of between 5% and 16% were recorded, consistent with previous comparisons for red deer open range counts in Scotland. CVs were lowest for ground and helicopter counts. The infrequency of optimal conditions was likely to limit the applicability of infrared counts in Scotland.

In terms of cost‐effectiveness, helicopter counting was the least labour‐intensive, with costs of other techniques depending on the availability of existing manpower as an overhead cost.

It is concluded that helicopter counts are most likely to minimize errors while maximizing cost‐efficiency. Accuracy can be improved by the use of digital photography for counting larger deer groups. Estimates are likely to be improved further by increasing the frequency of counts and using the same methods, counters and routes for repeat counts.
Identification of pseudomurein cell wall binding domains
Authors: Steenbakkers Peter J. M. , Geerts Wim J. , Ayman‐Oz Nilgün A. , Keltjens Jan T.
Published: November 2006

Methanothermobacter thermautotrophicus is a methanogenic Gram‐positive microorganism with a cell wall consisting of pseudomurein. Currently, no information is available on extracellular pseudomurein biology and so far only two prophage pseudomurein autolysins, PeiW and PeiP, have been reported. In this paper we show that PeiW and PeiP contain two different N‐terminal pseudomurein cell wall binding domains. This finding was used to identify a novel domain, PB007923, on the M. thermautotrophicus genome present in 10 predicted open reading frames. Three homologues were identified in the Methanosphaera stadtmanae genome. Binding studies of fusion constructs of three separate PB007923 domains to green fluorescent protein revealed that it also constituted a cell wall binding domain. Both prophage domains and the PB007923 domain bound to the cell walls of Methanothermobacter species and fluorescence microscopy showed a preference for the septal region. Domain specificities were revealed by binding studies with other pseudomurein‐containing archaea. Localized binding was observed for M. stadtmanae and Methanobrevibacter species, while others stained evenly. The identification of the first pseudomurein cell wall binding domains reveals the dynamics of the pseudomurein cell wall and provides marker proteins to study the extracellular pseudomurein biology of M. thermautotrophicus and of other pseudomurein‐containing archaea.
Immunocytochemical identification of interstitial cells of Cajal in the murine fundus using a live‐labelling technique
Authors: Stratton C. J. , Ward S. M. , Horiguchi K. , Sanders K. M.
Published: November 2006

Abstract  Interstitial cells of Cajal (ICC) within the gastrointestinal (GI) tract play a critical role in the generation of electrical slow waves and as mediators of enteric motor neurotransmission. Kit immunohistochemistry has proven to be a reliable method to identify the location of these cells within the tunica muscularis and to provide information on how the distribution and density of these cells change in a variety of GI motility disorders. Because of the labile nature of Kit or its detection, ultrastructural immunocytochemistry using conventional chemical fixation methods has been difficult. We describe a novel in vivo technique to label ICC within GI tissues. Using antibodies directed against the extracellular domain of the Kit receptor, we have been able to live‐label the stomach with Kit while the animal is under anaesthesia and the organ is still receiving normal blood supply. This approach provided optimum maintenance of ultrastructural features with significant binding of antibody to the Kit receptor. The loss of ICC in many human motility disorders suggests exciting new hypotheses for their aetiology. This method will prove useful to investigate the ultrastructural changes that occur in ICC networks in animal models of motility disorders that are associated with the loss of these cells.
Is there an experimental basis for the development of ischaemic colitis as a result of 5‐HT3 antagonist treatment?
Authors: Camilleri M.
Published: November 2006

Abstract  5‐HT3 antagonists are effective treatments for chemotherapy‐induced emesis and diarrhoea and urgency and pain associated with irritable bowel syndrome. Reports of ischaemic colitis led to restricted use of the approved drug, alosetron. This article briefly reviews the controversial information from epidemiology and adverse reaction reports and addresses the experimental basis for the development of ischaemic colitis as a result of 5‐HT3 antagonist treatment. The author reviews the potential factors based involved in the ischaemic colitis and ways in which this class of compound may influence those factors based on experimental evidence, including the literature on any vascular effects of these agents. Finally, the article addresses the theoretical basis for the constipation as a predisposing factor for the development of ischaemic colitis. The evidence reviewed suggests that further studies are needed to explore the principles to prove or disprove the association.