bluuebunny/crossref_metadata_2025 huggingface dataset:
Negative refraction of dipole-exchange spin waves through a magnetic twin interface in restricted geometry
Authors: Kim Sang-Koog , Choi Sangkook , Lee Ki-Suk , Han Dong-Soo , Jung Dae-Eun , Choi Youn-Seok
Published: May 2008

A phenomenon of negative refraction of dipole-exchange spin waves (DESWs) was demonstrated by micromagnetic modeling, based on the fact that the DESWs’ dispersion is anisotropic according to the relative orientation of the DESW propagation direction with respect to the orientation of local static magnetizations. Using this anisotropic dispersion behavior, the negative refraction of the DESWs was reproduced through a magnetic twin interface in a geometrically restricted medium of cubic in-plane anisotropy. This work verifies that the negative refraction of electromagnetic waves can also occur for DESWs propagating in restricted geometry through a specially designed magnetic interface.
Studies of the plasmonic properties of two-dimensional metallic nanobottle arrays
Authors: Li J. , Iu H. , Luk W. C. , Wan J. T. K. , Ong H. C.
Published: May 2008

Two-dimensional metallic nanobottle arrays with different aperture sizes have been fabricated by using interference lithography and their corresponding dispersion relations have been mapped by angle-dependent reflectivity measurement. Verified by finite-difference time-domain simulation, features arising from Bragg scattered surface plasmon polaritons (SPPs), localized SPPs, and Wood’s anomalies are clearly observed from the dispersion relations. In addition, it is found that changing the aperture size of the nanobottle can strongly modify the field strength and pattern of the SPPs. It is expected that nanobottle arrays can find applications in areas such as surface-enhanced Raman scattering and thermovoltaic devices.
Lateral Si∕SiO2 quantum well solar cells
Authors: Rölver R. , Berghoff B. , Bätzner D. L. , Spangenberg B. , Kurz H.
Published: May 2008

The photovoltaic properties of Si∕SiO2 multiple quantum wells (QWs) embedded in lateral Schottky contacts are investigated. The QWs were fabricated by remote plasma enhanced chemical vapor deposition. By subsequent rapid thermal annealing, the two-dimensional Si layers are partially recrystallized, which gives rise to distinct quantum confinement effects. Although the current extraction along the quantum layers is hampered by the incomplete recrystallization, the data collected define the route to optimized Si based QW solar cells.
Anion detection using ultrathin InN ion selective field effect transistors
Authors: Lu Yen-Sheng , Ho Chien-Lin , Yeh J. Andrew , Lin Hon-Way , Gwo Shangjr
Published: May 2008

Ultrathin (∼10nm) InN ion selective field effect transistors (ISFETs) have been demonstrated to perform ion sensing in aqueous solutions with a sensitivity of 5μA/decade and a response time smaller than 10s. The positively charged surface states on InN surfaces selectively adsorb anions, building Helmholtz voltages in solutions and modulating the drain-source current of the ISFETs. The ISFET performance is greatly enhanced by depleting carriers in the ultrathin InN channel where the film thickness is close to depth of surface electron accumulation.
Wettability patterning of lithium niobate substrate by modulating pyroelectric effect to form microarray of sessile droplets
Authors: Ferraro Pietro , Grilli Simonetta , Miccio Lisa , Vespini Veronica
Published: May 2008

The wettability of lithium niobate crystals was patterned by inducing the pyroelectric effect onto domain engineered samples. Compared to conventional electrowetting experiments, this technique allows one to obtain wettability patterning by an electrodeless configuration. In fact, the surface charges inducing the effect were generated pyroelectrically and spatially modulated by the domain grating. A microarray of sessile droplets was obtained on a single chip. Results and physical interpretation of the phenomena are reported and discussed.
Enhancing lifetime of carbon nanotube field emitters through hydrocarbon exposure
Authors: Fennimore A. M. , Roach D. H. , Wilson G. A. , Pellicone F. M. , Cheng L. T.
Published: May 2008

The effect of carbon containing gasses on the field emission degradation rate of carbon nanotube field emission devices has been measured. Long chain hydrocarbons were seen to form a carbonaceous deposit on the anode surface which effectively lowered the degradation rate. Simple hydrocarbons such as methane, ethylene, and acetylene reversed degradation by continually enhancing emission. This continuous enhancement was repeatable and continued over 500h. Carbon dioxide exposure at low partial pressures resulted in an increased field emission degradation rate similar to oxygen and water exposure as reported earlier.
Monodispersed polygonal water droplets in microchannel
Authors: Mehrotra Rajat , Jing Nan , Kameoka Jun
Published: May 2008

A microfluidic cross junction geometry was used to study the formation and modification of water droplets in oil media. Water droplets were formed from two horizontally opposing side channels alternatively. Then, their shapes were dynamically modified while transiting in the microchannel. There were three regimes of droplet shapes, circular, triangular, and rectangular shapes, which were determined by the volume ratio of water droplet in oil phase in microfluidic channels. All droplets formed in this experiment were monodispersed.
A microfluidic device for physical trapping and electrical lysis of bacterial cells
Authors: Bao Ning , Lu Chang
Published: May 2008

In this letter, we report a simple microfluidic device that integrates the capture of bacterial cells using a microscale bead array and the rapid electrical lysis for release of intracellular materials. We study the retention of Escherichia coli cells with different concentrations in this type of bead array and the optimal electrical parameters for the electroporative release of intracellular proteins. Our design provides a simple solution to the extraction of intracellular materials from a bacterial cell population based entirely on physical methods without applying chemical or biological reagents.
The role of vacancy on trapping interstitial O in heavily As-doped Si
Authors: Lu Guang-Hong , Wang Q. , Liu Feng
Published: May 2008

We have investigated the interstitial oxygen (Oi) diffusion in heavily arsenic (As)-doped Si using first-principles calculations. We show that it is not the As per se but the Si vacancy (V) that trap Oi to reduce its diffusion. Arsenic actually plays the role of an arbitrator to activate thermal generation of As–V pairs, which in turn trap Oi with a large binding energy of ∼1.0eV, in quantitative agreement with experiments. Our finding solves a long-standing puzzle on the atomistic mechanism underlying the retardation of Oi precipitation in heavily As-doped Si.
Integration of thin layers of single-crystalline InP with flexible substrates
Authors: Chen Wayne , Chen Peng , Pulsifer J. E. , Alford T. L. , Kuech T. F. , Lau S. S.
Published: May 2008

Transfer of thin semiconductor layers onto flexible substrates using a combination of ion cutting, adhesive bonding, and laser ablation was investigated. An ∼1.3μm thick InP layer was first transferred onto sapphire using adhesive bonding and hydrogen-induced layer exfoliation at ∼180°C. The resulting structure was then adhesively bonded onto flexible polyethylene naphthalate substrate, followed by UV laser ablation of the first adhesive to separate the initial bond. Additional transfer steps were inserted into the process to enable thermal annealing and electrical recovery. The transferred films were electrically characterized and the potential use in high-speed, flexible electronics is discussed.
Thermal rectification at silicon-amorphous polyethylene interface
Authors: Hu Ming , Keblinski Pawel , Li Baowen
Published: May 2008

Using nonequilibrium molecular dynamics simulations, we study the thermal diode effect in a system composed of inorganic crystal and amorphous polymer by imposing a series of positive and negative heat currents. We estimate that in the limit of large heat currents, the silicon-amorphous polyethylene interfacial thermal conductance is about 19.6 and 13.5MW∕m2K at room temperature for heat flowing from polymer to silicon and from silicon to polymer, respectively, which results in thermal rectification of up to 45%. Vibrational analysis indicates that the origin of thermal rectification is in the strong temperature dependence of the frequency spectra of the polymer.
Gate control of spin transport in multilayer graphene
Authors: Goto H. , Kanda A. , Sato T. , Tanaka S. , Ootuka Y. , Odaka S. , Miyazaki H. , Tsukagoshi K. , Aoyagi Y.
Published: May 2008

We experimentally studied the gate voltage dependence of spin transport in multilayer graphene (MLG) using the nonlocal spin detection technique. We found that the spin signal is a monotonically decreasing linear function of the resistance of MLG, which is characteristic of the intermediate interfacial transparency between the MLG and the ferromagnetic electrodes (Co). The linear relation indicates a large spin relaxation length significantly exceeding 8μm. This shows the superiority of MLG for the utilization of the graphite-based spintronic devices.
Dynamical theory for diffractive x-ray imaging of one-dimensional periodic objects
Authors: Nygård K. , Satapathy D. K. , Bunk O. , Pfeiffer F. , David C. , van der Veen J. F.
Published: May 2008

A dynamical theory for diffractive x-ray imaging of one-dimensional periodic objects is derived by solving the Helmholtz equation in the parabolic approximation using the coupled-wave theory. A method to account for volume-diffraction effects, based on propagating backwards the eigenmodes of the microfluidic array, is demonstrated for a colloidal suspension in confinement.
For a Geohistorical Cosmopolitanism: Postcolonial State Strategies, Cosmopolitan Communities, and the Production of the ‘British’, ‘Overseas’, ‘Non-Resident’, and ‘Global’ Indian
Authors: Edwards Kate
Published: May 2008

In this paper I seek to contribute to the burgeoning literature on cosmopolitanism by drawing on Ulrich Beck's work on the cosmopolitan implications of globalisation. In doing so, I argue that insights gained from Beckian understandings of risk and cosmopolitanism can be ‘ab-used’ to reclaim their potential for scholarship in postcolonial contexts. Drawing on the work of Bob Jessop, I critique Beck's argument via its extension and explore the production of ‘cosmopolitan communities’ which are far from neutrally cosmopolitan. The paper examines how ‘cosmopolitan communities’ can be usefully envisaged not solely as a necessary response to world risks, but also as the contingent outcome of state strategies designed to manage forms of political and economic uncertainty by reconfiguring geopolitical space. The state strategies explored here are ones which have sought to reconfigure social forces by rearticulating discourse on the identity of overseas populations, to harness their boundary crossing, or cosmopolitan, material and representational resources. Rethinking the emergence of ‘cosmopolitan communities’ and identities in this manner allows them to be defined by, and anchored in, different geopolitical orders and geohistorical contexts. The empirical context which substantiates this argument is offered by exploring four key moments in the Indian state's strategic-relational approach to its overseas populations from 1900 to 2003. In this paper, the terms ‘cosmopolitanism’ and ‘cosmopolitan communities’ are, therefore, deployed to refer to a geohistorically deep experience of cultivating geopolitical relations across borders. The paper maintains that ‘cosmopolitan communities’ exist alongside, go beyond, and also existed before political arenas defined by nation-centred accounts of history and geography.
Kicking Away the Ladder: Student Politics and the Making of an Indian Middle Class
Authors: Jeffrey Craig
Published: May 2008

In many poorer countries, middle classes are reshaping economic and political life, and nowhere is this process more evident than in postcolonial India. This paper uses ethnographic research on student politicians from rich farming backgrounds to reflect on class ‘in the making’. Building on a critical reading of the work of Bourdieu, I document the ability of young men from rich farming families in western Uttar Pradesh to entrench their middle-class standing in the space of university politics. I pay particular attention to the local-level political networks through which upwardly mobile young men from rural middle-caste backgrounds seek to express, legitimate, and secure their power. The paper points to the imaginative and energetic manner in which middle classes in poorer countries may defend their interests within local politics. I stress the importance of studying middle-class formation relationally and with reference to the spatiality of power.
Contesting Europe: The Politics of Bosnian Integration into European Structures
Authors: Jeffrey Alex
Published: May 2008

This paper explores what is meant by ‘being European’ in contemporary Bosnia. Over the past two decades, Western politicians have justified interventions in Bosnia through recourse to an Orientalist binary between a rational and progressive ‘Europe’, and an irrational and retrogressive ‘Balkans’. Current efforts to incorporate Bosnia into European structures reproduce this imaginary, in this instance though replacing space with time, suggesting that Bosnia needs to move from a ‘Balkan’ past to a ‘European’ future. In this paper I explore the political effects of such imaginaries through two levels of analysis. In the first, I critically examine the ongoing implications of the geopolitical framing of Bosnia as Europe's ‘Other’. In the second, I explore how nationalist politicians have deployed European rhetoric in order to stake claims to resources and establish respect. I conclude by arguing that a sovereignty paradox underpins both ‘geopolitical’ and ‘nationalist’ European rubrics in Bosnia: while idealising forms of solidarity based on broad social and cultural affiliations, such discourses simultaneously seek to promote the state as the primary territorialisation of political life.
Synthesis of linked carbon monolayers: Films, balloons, tubes, and pleated sheets
Authors: Schultz Mitchell J. , Zhang Xiaoyu , Unarunotai Sakulsuk , Khang Dahl-Young , Cao Qing , Wang Congjun , Lei Changhui , MacLaren Scott , Soares Julio A. N. T. , Petrov Ivan , Moore Jeffrey S. , Rogers John A.
Published: May 2008

Because of their potential for use in advanced electronic, nanomechanical, and other applications, large two-dimensional, carbon-rich networks have become an important target to the scientific community. Current methods for the synthesis of these materials have many limitations including lack of molecular-level control and poor diversity. Here, we present a method for the synthesis of two-dimensional carbon nanomaterials synthesized by Mo- and Cu-catalyzed cross-linking of alkyne-containing self-assembled monolayers on SiO
2
and Si
3
N
4
. When deposited and cross-linked on flat surfaces, spheres, cylinders, or textured substrates, monolayers take the form of these templates and retain their structure on template removal. These nanomaterials can also be transferred from surface to surface and suspended over cavities without tearing. This approach to the synthesis of monolayer carbon networks greatly expands the chemistry, morphology, and size of carbon films accessible for analysis and device applications.
Social interaction-mediated lifespan extension of
Drosophila
Cu/Zn superoxide dismutase mutants
Authors: Ruan Hongyu , Wu Chun-Fang
Published: May 2008

Beneficial effects of social interaction on aging have been studied in humans and other species. We found that short-lived
Drosophila
mutants of the antioxidant enzyme Cu/Zn superoxide dismutase displayed a robust lifespan extension, with improved stress resistance and motor ability, upon cohousing with active flies of longer lifespan or younger age. Genetic, surgical, and environmental manipulations revealed motor and sensory components in behavioral interactions required for the lifespan extension induced by cohousing. Our results provide a definitive case of beneficial social interaction on lifespan and a useful entry point for analyzing the underlying molecular networks and physiological mechanisms.
In vivo
two-photon voltage-sensitive dye imaging reveals top-down control of cortical layers 1 and 2 during wakefulness
Authors: Kuhn B. , Denk W. , Bruno R. M.
Published: May 2008

Conventional methods of imaging membrane potential changes have limited spatial resolution, particularly along the axis perpendicular to the cortical surface. The laminar organization of the cortex suggests, however, that the distribution of activity in depth is not uniform. We developed a technique to resolve network activity of different cortical layers
in vivo
using two-photon microscopy of the voltage-sensitive dye (VSD) ANNINE-6. We imaged spontaneous voltage changes in the barrel field of the somatosensory cortex of head-restrained mice and analyzed their spatiotemporal correlations during anesthesia and wakefulness. EEG recordings always correlated more strongly with VSD signals in layer (L) 2 than in L1. Nearby (<200 μm) cortical areas were correlated with one another during anesthesia. Waking the mouse strongly desynchronized neighboring cortical areas in L1 in the 4- to 10-Hz frequency band. Wakefulness also slightly increased synchrony of neighboring territories in L2 in the 0.5- to 4.0-Hz range. Our observations are consistent with the idea that, in the awake animal, long-range inputs to L1 of the sensory cortex from various cortical and thalamic areas exert top-down control on sensory processing.
Et si le proto-bantu était aussi une langue … avec ses contraintes et ses déséquilibres
Authors: Teil-Dautrey Gisèle
Published: May 2008

This article aims to define the phonological structure of Proto-Bantu lexical units on the basis of frequencies of reconstructed consonant co-occurrences. Starting from the main reconstructions given in BLR3, I present evidence for the presence of unexpected frequencies indicating imbalances in two directions. Certain consonant co-occurrences have not been reconstructed, essentially consonants sharing the same place of articulation and differing by only one feature, either voicing or nasality. These “gaps” in the proto-lexicon turn out to correspond to more general constraints that tend, on the one hand, towards the differentiation of place of articulation and, on the other hand, on agreement in voicing and nasality. However, in cases where *C1 and *C2 share the same place of articulation, Proto-Bantu seems to prefer identity over similarity. In looking to establish a link between the phonotactic constraints of the mother language and those of daughter languages, the latter take different directions, either a direction identical to that of the mother language, or a divergent one. In the reconstructions, the constraints on the nasality feature show similarities to those present in contemporary languages: Ganda has extended the constraint reconstructed for alveolars to all co-occurrences between a voiced stop and a nasal with the same place of articulation. However, the constraints on voicing generated by the dissimilation rule known as Dahl’s Law go in a divergent direction. I bring support here for the view that Dahl’s Law is in fact a daughter-language innovation. Furthermore, I show that this innovation was probably induced by the imbalances of the mother language; the rule fills Proto-Bantu distributional gaps. Finally, I discuss the implications of this study for the Obligatory Contour Principle (OCP).
Past, present, and future research on emblems in the Hispanic tradition
Authors: Payrató Lluís
Published: May 2008

Emblems or emblematic gestures have been recognized as a category or type of gesture in many studies, ever since the pioneering work by Efron (1941) and the well-known typology of Ekman and Friesen (1969). In the Mediterranean area, the study of characteristic emblems shows very different patterns of combinations of linguistic and cultural features, and also of transference or interference between emblems as conventional communicative signals, which may be intimately associated with linguistic varieties and/or cultural backgrounds. The case of the linguistic and cultural contact between Catalan and Spanish offers some interesting tokens of this kind, which can serve as the starting-point for research into emblems throughout the Mediterranean region. The resulting distribution of the historical evolution of the same original emblems and verbal expressions on the one hand and recent borrowings on the other makes the Mediterranean region a particularly interesting laboratory for the analysis of multimodal communicative acts. The distribution patterns of emblems depend on factors such as historical origin, geographical spread, and their relation to verbal items. With regard to the last factor, some emblems seem to have been created from idiomatic expressions, but many others have a clear cultural basis, and are not so closely linked to spoken language.
Is pointing “just” pointing?
Authors: Antinoro Pizzuto Elena , Capobianco Micaela
Published: May 2008

This paper examines the nature and properties of gestural and vocal deixis in verbal languages (VL) and signed languages (SL). We focus on two classes of pointing gestures which we argue need to be distinguished: (1) prototypical ostensive printings directing an interlocutor’s visual attention towards extralinguistic objects; (2) pointings to self and to one’s own addressee expressing person reference distinctions similar to those expressed by spoken pronouns. Drawing on previous work on SL and VL, and on new evidence on the development of deictic gestures and words for demonstrative vs. person reference in hearing children, we show how the two classes of pointings we explore convey indexical relationships of different complexity, and thus need to be distinguished in order to achieve a more appropriate understanding of gestural deixis, and of its relationship with vocal and, more generally, linguistic deixis.
Supplementing an uncertain investment?
Authors: Gao Xuesong , Cheng Huiman , Kelly Peter
Published: May 2008

This paper reports on a study into the motives underlying the formation of a weekly English discussion group organized by mainland Chinese research students in Hong Kong as a strategic effort to improve their English. Adopting a sociocultural approach, we compared our interpretations of semi-structured interview transcripts and other data, focusing in particular the participants’ strong English learning motivation. It was found that their motives were very complex and could best be explained by the notion of investment (Norton, 1995). These motives also became the primary forces that transformed the weekly event from a learning event into a variety of activities that moved beyond improving their English speaking skills for individual participants. The paper argues that a more sociocultural or sociopolitical perspective on learning strategy should be adopted to deepen our understanding of language learners’ strategic learning behaviour.
Identity construction and investment transformation
Authors: Gu Mingyue
Published: May 2008

This paper reports on a qualitative study that investigated the identity negotiation and English learning investment transformation of learners in a Chinese university. The informants included three female undergraduate students from English and Bioscience majors enrolled in a Chinese university. Recordings of conversation, students’ self-reports, and interviews were collected over one and a half years. This paper draws on ideas from the framework of communities of practice (Wenger, 1998), and employs the notions of identity, investment (Norton, 2000). The paper examined how English second language (L2) learners constructed multiple identities to position themselves in a Chinese educated urban community and an English speaking Christian community. It analysed how their participation and identities in the two communities were constructed, and how their motivation for learning English was transformed. The study reveals how, in an era of globalization, and specifically in the rapidly changing economic, sociocultural and political context of the People’s Republic of China (PRC), English language learning entails complex and intertwined issues of motivation, identity and culture, which demand further exploration.
The “other(ing)” costs of ESL
Authors: Lee Ena
Published: May 2008

While the commodification of English as a global language may give rise to varying degrees of political and economic benefits for language learners, a simultaneous “cost” of this return may be a continued perpetuation of various forms of hegemony. In this vein, this one-year case study investigated a Canadian post-secondary English as a Second Language (ESL) program that analyzed the interconnections between language and culture through a critical dialogic approach. Classroom observations, however, revealed that disjunctions existed between the pedagogy as it was conceptualized and the practices of the instructors teaching there and suggested that the “critical” discourses mediated within the language classrooms essentialized culture and, subsequently, the identities of the students. This paper presents the voices of students from Mainland China as they attempted to negotiate their local and global identities within the larger sociopolitical contexts of the English language, generally, and English language education, in particular. I argue that classroom discourses can (re)create subordinate student identities, thereby limiting their access not only to language-learning opportunities, but to other more powerful identities. This paper thus highlights how ESL pedagogies and practices might address and contest hegemonic discourses and concomitantly reimagine student identities in more emancipatory ways.
Linking Ras to myosin function: RasGEF Q, aDictyosteliumexchange factor for RasB, affects myosin II functions
Authors: Mondal Subhanjan , Bakthavatsalam Deenadayalan , Steimle Paul , Gassen Berthold , Rivero Francisco , Noegel Angelika A.
Published: May 2008

Ras guanine nucleotide exchange factor (GEF) Q, a nucleotide exchange factor from Dictyostelium discoideum, is a 143-kD protein containing RasGEF domains and a DEP domain. We show that RasGEF Q can bind to F-actin, has the potential to form complexes with myosin heavy chain kinase (MHCK) A that contain active RasB, and is the predominant exchange factor for RasB. Overexpression of the RasGEF Q GEF domain activates RasB, causes enhanced recruitment of MHCK A to the cortex, and leads to cytokinesis defects in suspension, phenocopying cells expressing constitutively active RasB, and myosin-null mutants. RasGEF Q− mutants have defects in cell sorting and slug migration during later stages of development, in addition to cell polarity defects. Furthermore, RasGEF Q− mutants have increased levels of unphosphorylated myosin II, resulting in myosin II overassembly. Collectively, our results suggest that starvation signals through RasGEF Q to activate RasB, which then regulates processes requiring myosin II.
Suppression of neuropil aggregates and neurological symptoms by an intracellular antibody implicates the cytoplasmic toxicity of mutant huntingtin
Authors: Wang Chuan-En , Zhou Hui , McGuire John R. , Cerullo Vincenzo , Lee Brendan , Li Shi-Hua , Li Xiao-Jiang
Published: May 2008

Mutant huntingtin accumulates in the neuronal nuclei and processes, which suggests that its subcellular localization is critical for the pathology of Huntington's disease (HD). However, the contribution of cytoplasmic mutant huntingtin and its aggregates in neuronal processes (neuropil aggregates) has not been rigorously explored. We generated an intracellular antibody (intrabody) whose binding to a unique epitope of human huntingtin is enhanced by polyglutamine expansion. This intrabody decreases the cytotoxicity of mutant huntingtin and its distribution in neuronal processes. When expressed in the striatum of HD mice via adenoviral infection, the intrabody reduces neuropil aggregate formation and ameliorates neurological symptoms. Interaction of the intrabody with mutant huntingtin increases the ubiquitination of cytoplasmic huntingtin and its degradation. These findings suggest that the intrabody reduces the specific neurotoxicity of cytoplasmic mutant huntingtin and its associated neurological symptoms by preventing the accumulation of mutant huntingtin in neuronal processes and promoting its clearance in the cytoplasm.
DTNBP1, a schizophrenia susceptibility gene, affects kinetics of transmitter release
Authors: Chen Xiao-Wei , Feng Ya-Qin , Hao Chan-Juan , Guo Xiao-Li , He Xin , Zhou Zhi-Yong , Guo Ning , Huang Hong-Ping , Xiong Wei , Zheng Hui , Zuo Pan-Li , Zhang Claire Xi , Li Wei , Zhou Zhuan
Published: May 2008

Schizophrenia is one of the most debilitating neuropsychiatric disorders, affecting 0.5–1.0% of the population worldwide. Its pathology, attributed to defects in synaptic transmission, remains elusive. The dystrobrevin-binding protein 1 (DTNBP1) gene, which encodes a coiled-coil protein, dysbindin, is a major susceptibility gene for schizophrenia. Our previous results have demonstrated that the sandy (sdy) mouse harbors a spontaneously occurring deletion in the DTNBP1 gene and expresses no dysbindin protein (Li, W., Q. Zhang, N. Oiso, E.K. Novak, R. Gautam, E.P. O'Brien, C.L. Tinsley, D.J. Blake, R.A. Spritz, N.G. Copeland, et al. 2003. Nat. Genet. 35:84–89). Here, using amperometry, whole-cell patch clamping, and electron microscopy techniques, we discovered specific defects in neurosecretion and vesicular morphology in neuroendocrine cells and hippocampal synapses at the single vesicle level in sdy mice. These defects include larger vesicle size, slower quantal vesicle release, lower release probability, and smaller total population of the readily releasable vesicle pool. These findings suggest that dysbindin functions to regulate exocytosis and vesicle biogenesis in endocrine cells and neurons. Our work also suggests a possible mechanism in the pathogenesis of schizophrenia at the synaptic level.
Reversible cytoplasmic localization of the proteasome in quiescent yeast cells
Authors: Laporte Damien , Salin Bénédicte , Daignan-Fornier Bertrand , Sagot Isabelle
Published: May 2008

The 26S proteasome is responsible for the controlled proteolysis of a vast number of proteins, including crucial cell cycle regulators. Accordingly, in Saccharomyces cerevisiae, 26S proteasome function is mandatory for cell cycle progression. In budding yeast, the 26S proteasome is assembled in the nucleus, where it is localized throughout the cell cycle. We report that upon cell entry into quiescence, proteasome subunits massively relocalize from the nucleus into motile cytoplasmic structures. We further demonstrate that these structures are proteasome cytoplasmic reservoirs that are rapidly mobilized upon exit from quiescence. Therefore, we have named these previously unknown structures proteasome storage granules (PSGs). Finally, we observe conserved formation and mobilization of these PSGs in the evolutionary distant yeast Schizosaccharomyces pombe. This conservation implies a broad significance for these proteasome reserves.
A generic mechanism inNeisseria meningitidisfor enhanced resistance against bactericidal antibodies
Authors: Uria Maria Jose , Zhang Qian , Li Yanwen , Chan Angel , Exley Rachel M. , Gollan Bridget , Chan Hannah , Feavers Ian , Yarwood Andy , Abad Raquel , Borrow Ray , Fleck Roland A. , Mulloy Barbara , Vazquez Julio A. , Tang Christoph M.
Published: May 2008

The presence of serum bactericidal antibodies is a proven correlate of protection against systemic infection with the important human pathogen Neisseria meningitidis. We have identified three serogroup C N. meningitidis (MenC) isolates recovered from patients with invasive meningococcal disease that resist killing by bactericidal antibodies induced by the MenC conjugate vaccine. None of the patients had received the vaccine, which has been successfully introduced in countries in North America and Europe. The increased resistance was not caused by changes either in lipopolysaccharide sialylation or acetylation of the α2-9–linked polysialic acid capsule. Instead, the resistance of the isolates resulted from the presence of an insertion sequence, IS1301, in the intergenic region (IGR) between the sia and ctr operons, which are necessary for capsule biosynthesis and export, respectively. The insertion sequence led to an increase in the transcript levels of surrounding genes and the amount of capsule expressed by the strains. The increased amount of capsule was associated with down-regulation of the alternative pathway of complement activation, providing a generic mechanism by which the bacterium protects itself against bactericidal antibodies. The strains with IS1301 in the IGR avoided complement-mediated lysis in the presence of bactericidal antibodies directed at the outer membrane protein, PorA, or raised against whole cells.
Atg8 Controls Phagophore Expansion during Autophagosome Formation
Authors: Xie Zhiping , Nair Usha , Klionsky Daniel J.
Published: May 2008

Autophagy is a potent intracellular degradation process with pivotal roles in health and disease. Atg8, a lipid-conjugated ubiquitin-like protein, is required for the formation of autophagosomes, double-membrane vesicles responsible for the delivery of cytoplasmic material to lysosomes. How and when Atg8 functions in this process, however, is not clear. Here we show that Atg8 controls the expansion of the autophagosome precursor, the phagophore, and give the first real-time, observation-based temporal dissection of the autophagosome formation process. We demonstrate that the amount of Atg8 determines the size of autophagosomes. During autophagosome biogenesis, Atg8 forms an expanding structure and later dissociates from the site of vesicle formation. On the basis of the dynamics of Atg8, we present a multistage model of autophagosome formation. This model provides a foundation for future analyses of the functions and dynamics of known autophagy-related proteins and for screening new genes.
Fluorescent Detection of Rat Parathyroid Glands via 5‐Aminolevulinic Acid
Authors: Asher Scott A. , Peters Glenn E. , Pehler Stephen F. , Zinn Kurt , Newman J Robert , Rosenthal Eben L.
Published: May 2008

Objective:Anatomic identification of parathyroid glands during surgery is challenging and time consuming. We sought to determine whether 5‐aminolevulinic acid (5‐ALA) could produce parathyroid gland fluorescence to improve their detection in a preclinical model.

Methods:Thirty‐two rats were administered 0 to 700 mg/kg of 5‐ALA by intraperitoneal injection prior to neck exploration under the illumination of a blue light (380–440 nm). Tissue fluorescence was assessed at 1, 2, or 4 hours postinjection and then removed for histologic confirmation of parathyroid tissue.

Results:Rat parathyroid glands could not be visualized under ambient light. At dosages of 300 mg/kg or greater, bilateral parathyroid glands were visualized in 18 of 19 rats using blue light illumination. At dosages less than 300 mg/kg, parathyroid gland fluorescence was detected in only 1 of 13 rats. At 2 hours after 5‐ALA administration, the net mean intensity of parathyroid gland fluorescence was optimal with a dose of 500 mg/kg. At both 1 and 4 hours after 5‐ALA injection, the net mean intensity of parathyroid gland fluorescence was optimal at the highest dose (700 mg/kg) and positively correlated with dosage increases.

Conclusion:5‐ALA can be used to selectively detect parathyroid tissue from surrounding tissue in a preclinical model. Our data support the use of this technique in the clinical setting.
Developing a Rabbit Model of Rhinogenic Chronic Rhinosinusitis
Authors: Liang Kai‐Li , Jiang Rong‐San , Wang John , Shiao Jiun‐Yih , Su Mao‐Chang , Hsin Chung‐Han , Lin Jen‐Fu
Published: May 2008

Objective: The purpose of this study was to develop a rabbit model of rhinogenic chronic rhinosinusitis (CRS).

Methods: New Zealand white rabbits were used and divided into two groups. In group A rabbits, a piece of Merocel (Medtronic‐Xomed, Jacksonville, FL) was inserted into one nasal cavity and the other was left undisturbed as control. In group B rabbits, 1 μg phorbol 12‐myristate 13‐acetate (PMA) was injected into bilateral nasal lateral walls and then a piece of Merocel (Medtronic‐Xomed) was inserted into one nasal cavity. At week 2, the Merocel (Medtronic‐Xomed) was removed, and computed tomography (CT), nasoendoscopy, and cultures were performed. All examinations were repeated at week 12. Rabbits that had purulent discharge in nasal cavities and sinuses opacification shown in CT scans were diagnosed as having rhinosinusitis. Rabbits with CRS were randomly allocated to receive intravenous ceftriaxone (50 mg/kg/day) for 28 days or nothing. All rabbits with CRS received CT scans, nasoendoscopy, and cultures at week 16.

Results: At week 12, CRS had developed in two controlled nasal cavities, six nasal cavities inserted with Merocel (Medtronic‐Xomed), six nasal cavities injected with phorbol 12‐myristate 13‐acetate (PMA), and seven both PMA‐injected and Merocel‐ (Medtronic‐Xomed) inserted nasal cavities. Seven of nine treated CRS sides were clear of opacification after treatment. All non‐treated CRS sides had persistent diseases at week 16. There was a significant difference in the CRS incidence (P = .00043) and culture rates (P = .027) between treated and non‐treated CRS nasal cavities.

Conclusions: Our study developed a rabbit model of rhinogenic CRS. This model is easily performed and is reversible by treatment.
Clinical Validation of Percutaneous Cochlear Implant Surgery: Initial Report
Authors: Labadie Robert Frederick , Noble Jack H. , Dawant Benoit M. , Balachandran Ramya , Majdani Omid , Fitzpatrick J Michael
Published: May 2008

Objective: Percutaneous cochlear implant surgery consists of a single drill path from the lateral mastoid cortex to the cochlea via the facial recess. We sought to clinically validate this technique in patients undergoing traditional cochlear implant surgery.

Study Design: Prospective clinical trial.

Methods: After institutional regulatory board‐approved protocols, five ears were studied via the following steps. 1) In the clinic under local anesthesia, bone‐implanted anchors were placed surrounding each mastoid. 2) Temporal‐bone computed tomography (CT) scans were obtained. 3) On the CT scans, paths were planned from the lateral mastoid cortex, through the facial recess, to the basal turn of the cochlea both “manually” and “automatically” using computer software. 4) Customized microstereotactic frames were rapid‐prototyped to serve as drill guides constraining the drill to follow the appropriate path. 5) During cochlear implant surgery, after drilling of the facial recess, drill guides were mounted on the bone‐implanted anchors. 6) Accuracy of paths was assessed via intraoperative photodocumentation.

Results: All surgical paths successfully traversed the facial recess and hit the basal turn of the cochlea. Distance in millimeters (average ± SD) from the midpoint of the drill to the facial nerve was 1.18 ± 0.68 for the “manual” path and 1.24 ± 0.44 mm for the “automatic” path and for the chorda tympani 0.986 ± 0.48 for the “manual” path and 1.22 ± 0.62 for the “automatic” path.

Conclusions: Percutaneous cochlear implant access using customized drill guides based on preoperative CT scans and image‐guided surgery technology can be safely accomplished.
Long‐Term Hearing Results in Gamma Knife Radiosurgery for Acoustic Neuromas
Authors: Bush Matthew L. , Shinn Jennifer B. , Young A Byron , Jones Raleigh O.
Published: May 2008

Objectives: There are many studies that have examined functional outcomes following Gamma Knife treatment; however, few have reported long‐term audiometric data. This study analyzed the long‐term hearing results of Gamma Knife radiosurgery in the treatment of acoustic neuromas.

Study Design: Retrospective cohort study.

Methods: Seventeen patients were selected from our acoustic neuroma Gamma Knife registry of 113 patients treated from 1991 to 2005. Pretreatment audiograms were analyzed for pure‐tone average and word recognition scores and assigned a Gardner‐Robertson classification score (GRC). Either a current audiogram was obtained or the most recent audiogram (if the patient was lost to follow‐up) was reviewed from clinic charts and these were compared with the preoperative results. Audiometric data of the pre‐ and posttreatment normal ear were obtained and used as the patient's own control.

Results: The tumor size ranged from 0.5 to 2.8 cm (mean, 1.33 cm) and patients received a range of 12.5–16 Gy (mean, 13.82 Gy) to 50% isodose line. Patient follow‐up ranged from 3 to 82 months with a mean of 33.6 months. Pretreatment pure‐tone average for the involved side group was 30.6 dB HL with a word recognition score of 74%. Pretreatment mean GRC was 1.76. posttreatment pure‐tone average for the group was 59.7 dB HL with a word recognition score of 37%. posttreatment mean GRC was 3.29. Comparing pre‐ versus post‐Gamma Knife radiosurgery results on the treatment ear, means were statistically significantly different for both pure‐tone average and word recognition scores, based on a paired‐samples t test (P < .001 for both). The group “normal” ear pure‐tone average was 14 dB HL and 17.75 dB HL pre‐ and posttreat‐ment, respectively. Normal ear pre‐ and posttreatment word recognition score and GRC were 93% and 98%, and 1.13 and 1.31, respectively.

Conclusion: Gamma Knife radiosurgery remains a noninvasive treatment option for patients with acoustic neuromas; however, they may experience a delayed hearing loss. Of those patients with useful audition pretreatment, 42% maintained useful hearing posttreatment.
On the modelling of semi-insulating GaAs including surface tension and bulk stresses
Authors: Dreyer Wolfgang , Duderstadt Frank
Published: May 2008

The necessary heat treatment of single-crystal semi-insulating gallium arsenide (GaAs), which is deployed in micro- and optoelectronic devices, generates undesirable liquid precipitates in the solid phase. The appearance of precipitates is influenced by surface tension at the liquid–solid interface and deviatoric stresses in the solid.

The central quantity for the description of the various aspects of phase transitions is the chemical potential, which can be additively decomposed into a chemical and a mechanical part. In particular, the calculation of the mechanical part of the chemical potential is of crucial importance. We determine the chemical potential in the framework of the St. Venant–Kirchhoff law, which gives an appropriate stress–strain relation for many solids in the small-strain regime. We establish criteria that allow the correct replacement of the St. Venant–Kirchhoff law by the simpler Hooke law.

The main objectives of this study are the following: (i) we develop a thermo-mechanical model that describes diffusion and interface motions, which are both strongly influenced by surface tension effects and deviatoric stresses, (ii) we give an overview and outlook on problems that can be posed and solved within the framework of the model, and (iii) we calculate non-standard phase diagrams for GaAs above 1059 K, i.e. those that take into account surface tension and deviatoric stresses, and we compare the results with classical phase diagrams without these phenomena.
Population density and sex do not influence fine-scale natal dispersal in roe deer
Authors: Gaillard J.-M , Hewison A.J.M , Kjellander P , Pettorelli N , Bonenfant C , Van Moorter B , Liberg O , Andren H , Van Laere G , Klein F , Angibault J.-M , Coulon A , Vanpé C
Published: May 2008

It is commonly assumed that the propensity to disperse and the dispersal distance of mammals should increase with increasing density and be greater among males than among females. However, most empirical evidence, especially on large mammals, has focused on highly polygynous and dimorphic species displaying female-defence mating tactics. We tested these predictions on roe deer, a weakly polygynous species of large herbivore exhibiting a resource-defence mating tactic at a fine spatial scale. Using three long-term studies of populations that were subject to the experimental manipulation of size, we did not find any support for either prediction, whether in terms of dispersal probability or dispersal distance. Our findings of similar dispersal patterns in both sexes of roe deer suggest that the underlying cause of natal dispersal is not related to inbreeding avoidance in this species. The absence of positive density dependence in fine-scale dispersal behaviour suggests that roe deer natal dispersal is a pre-saturation process that is shaped by heterogeneities in habitat quality rather than by densityper se.
Evolutionarily conserved coding properties of auditory neurons across grasshopper species
Authors: Neuhofer Daniela , Wohlgemuth Sandra , Stumpner Andreas , Ronacher Bernhard
Published: May 2008

We investigated encoding properties of identified auditory interneurons in two not closely related grasshopper species (Acrididae). The neurons can be homologized on the basis of their similar morphologies and physiologies. As test stimuli, we used the species-specific stridulation signals ofChorthippus biguttulus, which evidently are not relevant for the other species,Locusta migratoria. We recorded spike trains produced in response to these signals from several neuron types at the first levels of the auditory pathway in both species. Using a spike train metric to quantify differences between neuronal responses, we found a high similarity in the responses of homologous neurons: interspecific differences between the responses of homologous neurons in the two species were not significantly larger than intraspecific differences (between several specimens of a neuron in one species). These results suggest that the elements of the thoracic auditory pathway have been strongly conserved during the evolutionary divergence of these species. According to the ‘efficient coding’ hypothesis, an adaptation of the thoracic auditory pathway to the specific needs of acoustic communication could be expected. We conclude that there must have been stabilizing selective forces at work that conserved coding characteristics and prevented such an adaptation.
Crystal structure and mutagenic analysis of GDOsp, a gentisate 1,2‐dioxygenase from Silicibacter Pomeroyi
Authors: Chen Jia , Li Wei , Wang Mingzhu , Zhu Guangyu , Liu Dongqi , Sun Fei , Hao Ning , Li Xuemei , Rao Zihe , Zhang Xuejun C.
Published: May 2008

Dioxygenases catalyze dioxygen incorporation into various organic compounds and play a key role in the complex degradation pathway of mono‐ and polycyclic aromatic and hetero‐aromatic compounds. Here we report the crystal structure of gentisate 1,2‐dioxygenase from Silicibacter pomeroyi (GDOsp) at a 2.8 Å resolution. The enzyme possessed a conserved three‐dimensional structure of the bicupin family, forming a homotetramerization. However, each subunit of GDOsp unusually contained two ferrous centers that were located in its two homologous cupin domains, respectively. Further mutagenic analysis indicated that the enzyme activity of GDOsp depends on the microenvironment in both metal‐binding sites. Moreover, homologous structural comparison and functional study on GDOsp variants unveiled a group of functionally essential residues and suggested that the active site of the enzyme is located in the amino‐terminal domain, but could be influenced by changes in the carboxyl domain. Therefore, GDOsp may provide a working model for studying long‐distance communication within a protein (or its complex).