bluuebunny/crossref_metadata_2025 huggingface dataset:
Thymolipoma in a cat
Authors: Vilafranca Miquel , Font Artur
Published: January 2005

Thymolipomas are rare benign thymic neoplasms recognised in humans, composed of mature adipose tissue and thymic tissue. An 8-year-old male domestic shorthair cat presented with anorexia, lethargy and vomiting secondary to the development of a thoracic effusion and an anterior mediastinal tumoral mass with fatty appearance. Histologically, the mass consisted of adipose tissue containing numerous cords and nests of cortical and medullary thymic tissue. No signs of thymic epithelial or lymphoid neoplastic proliferation were detected. The findings in this case are remarkably similar to the macroscopic and histological features of thymolipoma in humans.
Suspected toxoplasma—Associated myocarditis in a cat
Authors: Simpson Kerry E , Devine B Craig , Gunn-Moore Danièlle
Published: January 2005

Clinical toxoplasmosis is commonly reported in the cat, with the most consistent findings being ocular, pulmonic, hepatic, neurological, gastrointestinal and muscular abnormalities. Myocarditis, whilst frequently identified at post-mortem examination, has not been identified ante-mortem.

In immunocompromised humans, myocarditis associated with toxoplasmosis is not an uncommon complication. In such cases, lymphocytic myocardial infiltration can lead to depressed myocardial function, which can be associated with congestive heart failure, rhythm disturbances and pericardial effusions. In addition, myocardial failure has been reported in immunocompetent humans associated with active toxoplasmosis [ Chandenier J, Jarry G, Nassif D, Douadi Y, Paris L, Thulliez P, Bourges-Petit E, Raccurt C (2000) Congestive heart failure and myocarditis after seroconversion for toxoplasmosis in two immunocompetent patients. European Journal of Clinical Microbiological Infectious Disease19, 375–379 ]. Here we describe a cat with echocardiographic changes consistent with infiltrative or inflammatory disease, and elevated IgG and IgM titres to Toxoplasma gondii. There was resolution of these myocardial changes once the toxoplasmosis was treated.
Age and extent of the Ilopango TBJ Tephra inferred from a Holocene chronostratigraphic reference section, Lago De Yojoa, Honduras
Authors: Mehringer Peter J. , Sarna-Wojcicki Andrei M. , Wollwage Lance K. , Sheets Payson
Published: January 2005

Eruption of central El Salvador's Ilopango Volcano early in the first millennium A.D. caused death, cultural devastation, and exodus of southern Mesoamericans. It also left a time-stratigraphic marker in western El Salvador and adjacent Guatemala—the Ilopango Tierra Blanca Joven, or TBJ tephra. Mineral suites and major element abundances identify a silicic volcanic ash in cores from Lago de Yojoa, Honduras, as Ilopango TBJ. This extends its reported range more than 150 km to the northeast. Analyses of glass from the TBJ tephra from the Chalchuapa archaeological site, El Salvador, and from Lago de Yojoa, Honduras, establish the first major element reference fingerprint for the TBJ tephra. The Lago de Yojoa cores also hold two previously undated trachyandesitic tephra layers originating from the nearby Lake Yojoa Volcanic Field. One fell shortly before 11,00014C yr B.P. and the other about 860014C yr B.P.
Pop goes the rapper: a close reading of Eminem's genderphobia
Authors: STEPHENS VINCENT
Published: January 2005

This article argues that controversial hip-hopper Eminem is more properly termed a genderphobe than a homophobe. Eminem consistently uses homophobic language to critique gender behaviour, not sexual orientation. Focusing on genderphobic lyrics more accurately reveals hip-hop culture's emphasis on gender behaviour rather than the emphasis on sexual object-choice that homophobia implies. The focus on genderphobia also highlights a discriminatory practice aimed toward external behaviour that is related to homophobia but operates differently in certain cultural realms. I ground my discussion by focusing on the centrality of authenticity in hip-hop and gender propriety's centrality in comprising hip-hop notions of authenticity. Additionally, I emphasise how all pop stars rely on personae to convey convincing images to the public. I conclude by analysing the Pet Shop Boys and Mariah Carey's ‘answer songs’, which directly address Eminem's genderphobia and authenticity.
‘Living underground is tough’: authenticity and locality in the hip-hop community in Istanbul, Turkey
Authors: SOLOMON THOMAS
Published: January 2005

Hip-hoppers in Istanbul, Turkey, spend much discursive energy talking and rapping about how the Turkish hip-hop movement is underground, putting a particularly local spin on their uses of a global cultural form. This spatial metaphor has thus become central to local constructions of hip-hop in Istanbul. This paper explores the different meanings the underground concept has for Turkish hip-hoppers through a combination of ethnographic research and readings of locally produced hip-hop texts. Through discourses on and around the underground metaphor, Turkish hip-hoppers use the globally circulating music genre of rap and the associated arts of hip-hop to construct a specifically local identity, re-emplacing rap and hip-hop within the landscape of Istanbul. The paper uses this case study to explore how people can use mediated music in constructing new imaginaries and identities and more specifically how people can use mediated music as a vehicle for the imagining of place.
‘Some guy designed this room I’m standing in': marking gender in press coverage of Ani DiFranco
Authors: FEIGENBAUM ANNA
Published: January 2005

Examining ways in which gender is marked in the press coverage of self-produced, folk-rock artist and record label owner Ani DiFranco, this paper explores how language employed in rock criticism frequently functions to devalue and marginalise women artists' musicianship, influence on fans, and contribution to the rock canon. Investigating how the readerships of different publications may influence the ways in which journalists mark gender in rock criticism, this study utilises a corpus of 100 articles on Ani DiFranco published between 1993 and 2003 from print and online magazines and newspapers in Canada, the United States and the United Kingdom. Focusing on the use of inter- and intra-gender artist comparisons, adjectival gender markers and ‘metaphorical gender’ markers in artist background information, lyrical and musical analyses and descriptions of fans, this analysis maps the discursive conventions that music critics and theorists continue to rely on in reviews and profiles of women artists.
‘Simply Irresistible’: recurring accent patterns as hooks in mainstream 1980s music
Authors: TRAUT DON
Published: January 2005

This essay explores connections between the notion of ‘hook’ and several recurring accent patterns found in rock music from the 1980s. It begins by identifying seven syncopated accent patterns and presents a list of over 150 songs from the 1980s that use one or more of these patterns. It then presents three main ways that the accent patterns help create ‘hooks’. First, several songs use one of the patterns to create a strong title hook, as in Rick Springfield's hit, ‘I’ve Done Everything for You', the title of which is set with a syncopated and distinct rhythmic pattern. A second type of ‘hook’ comes in the form of a ‘significant gesture’ that usually precedes the chorus. The pre-chorus ‘My-my-my-my, ah, woo!’ gesture from The Knack's ‘My Sharona’ is an excellent example. Finally, a third type of ‘hook’ involves the combination of a repeated accent pattern with a recurring pitch pattern, as in the guitar introduction to AC/DC's ‘For Those About to Rock’. By realising that these three examples all use the same accent pattern in significant, but different, ways, we acknowledge the prominence of this and other patterns while furthering the discourse on the notion of the ‘hook’.
Jews, punk and the Holocaust: from the Velvet Underground to the Ramones – the Jewish-American story
Authors: STRATTON JON
Published: January 2005

Punk is usually thought of as a radical reaction to local circumstances. This article argues that, while this may be the case, punk's celebration of nihilism should also be understood as an expression of the acknowledgement of the cultural trauma that was, in the late 1970s, becoming known as the Holocaust. This article identifies the disproportionate number of Jews who helped in the development of the American punk phenomenon through the late 1960s and 1970s. However, the effects of the impact of the cultural trauma of the Holocaust were not confined to Jews. The shock that apparently civilised Europeans could engage in genocidal acts against groups of people wholly or partially thought of by most Europeans as European undermined the certainties of post-Enlightenment modernity and contributed fundamentally to the sense of unsettlement of morals and ethics which characterises the experience of postmodernity. Punk marks a critical cultural moment in that transformation. In this article the focus is on punk in the United States.
THE ITALIAN MENACE: OPERA BUFFA IN REVOLUTIONARY FRANCE
Authors: MCCLELLAN MICHAEL E.
Published: January 2005

The Parisian premiere of Paisiello’s Nina, o sia la pazza d’amore on 3 September 1791 triggered a hostile reaction from French librettists and composers. Since the opéra comique on which Paisiello had based his opera remained in the active repertory of the Comédie-Italienne, Nina was considered an infringement of copyright legislation recently passed by the National Assembly. In the controversy that followed, matters involving intellectual property and opera aesthetics were linked to revolutionary struggle. At a time when clarity and transparency were identified as republican virtues in France, the carefully wrought balance between music and text that was associated with French operatic genres acquired new political resonance. Simultaneously, the perceived emphasis on sensual musical pleasure – at the expense of a coherent libretto – in Italian operas like Nina was eyed with suspicion, deemed a potential symptom of counterrevolution. In this way, the relative merits of French and Italian opera were superimposed on issues of revolution, reaction and national identity.
Heterogeneous nuclear ribonucleoprotein K represses transcription from a cytosine/thymidine-rich element in the osteocalcin promoter
Authors: STAINS Joseph P. , LECANDA Fernando , TOWLER Dwight A. , CIVITELLI Roberto
Published: January 2005

HnRNP K (heterogeneous nuclear ribonucleoprotein K) was biochemically purified from a screen of proteins co-purifying with binding activity to the osteocalcin promoter. We identify hnRNP K as a novel repressor of osteocalcin gene transcription. Overexpression of hnRNP K lowers the expression of osteocalcin mRNA by 5-fold. Furthermore, luciferase reporter assays demonstrate that overexpression of hnRNP K represses osteocalcin transcription from a CT (cytosine/thymidine)-rich element in the proximal promoter. Electrophoretic mobility-shift analysis reveals that recombinant hnRNP K binds to the CT-rich element, but binds ss (single-stranded), rather than ds (double-stranded) oligonucleotide probes. Accordingly, hnRNP K antibody can supershift a binding activity present in nuclear extracts using ss sense, but not antisense or ds oligonucleotides corresponding to the CT-rich −95 to −47 osteocalcin promoter. Importantly, addition of recombinant hnRNP K to ROS 17/2.8 nuclear extract disrupts formation of a DNA–protein complex on ds CT element oligonucleotides. This action is mutually exclusive with hnRNP K's ability to bind ss DNA. These results demonstrate that hnRNPK, although co-purified with a dsDNA-binding activity, does not itself bind dsDNA. Rather, hnRNP K represses osteocalcin gene transcription by inhibiting the formation of a transcriptional complex on the CT element of the osteocalcin promoter.
5-Aminoimidazole-4-carboxamide riboside (AICAR) enhances GLUT2-dependent jejunal glucose transport: a possible role for AMPK
Authors: WALKER John , JIJON Humberto B. , DIAZ Hugo , SALEHI Payam , CHURCHILL Thomas , MADSEN Karen L.
Published: January 2005

AMPK (AMP-activated protein kinase) is a key sensor of energy status within the cell. Activated by an increase in the AMP/ATP ratio, AMPK acts to limit cellular energy depletion by down-regulating selective ATP-dependent processes. The purpose of the present study was to determine the role of AMPK in regulating intestinal glucose transport. [3H]3-O-methyl glucose fluxes were measured in murine jejunum in the presence and absence of the AMPK activators AICAR (5-aminoimidazole-4-carboxamide riboside) and metformin and the p38 inhibitor, SB203580. To differentiate between a sodium-coupled (SGLT1) and diffusive (GLUT2) route of entry, fluxes were measured in the presence of the SGLT1 and GLUT2 inhibitors phloridzin and phloretin. Glucose transporter mRNA levels were measured by reverse transcriptase–PCR, and localization by Western blotting. Surface-expressed GLUT2 was assessed by luminal biotinylation. Activation of p38 mitogen-activated protein kinase was analysed by Western blotting. We found that treatment of jejunal tissue with AICAR resulted in enhanced net glucose uptake and was associated with phosphorylation of p38 mitogen-activated protein kinase. Inhibition of p38 abrogated the stimulation of AICAR-stimulated glucose uptake. Phloretin abolished the AICAR-mediated increase in glucose flux, whereas phloridzin had no effect, suggesting the involvement of GLUT2. In addition, AICAR decreased total protein levels of SGLT1, concurrently increasing levels of GLUT2 in the brush-border membrane. The anti-diabetic drug metformin, a known activator of AMPK, also induced the localization of GLUT2 to the luminal surface. We conclude that the activation of AMPK results in an up-regulation of non-energy requiring glucose uptake by GLUT2 and a concurrent down-regulation of sodium-dependent glucose transport.
Real-time imaging of myosin II regulatory light-chain phosphorylation using a new protein biosensor
Authors: YAMADA Aki , HIROSE Kenzo , HASHIMOTO Akiko , IINO Masamitsu
Published: January 2005

Phosphorylation of the RMLC (regulatory myosin light chain) regulates the activity of myosin II, which is critically involved in the motility of both muscle and non-muscle cells. There are both Ca2+-dependent and -independent pathways for RMLC phosphorylation in smooth-muscle cells, and the latter pathway is often involved in an abnormal contractility in pathological states such as asthma and hypertension. Therefore pharmacological interventions of RMLC phosphorylation may have a therapeutic value. In the present study, we developed a new genetically encoded biosensor, termed CRCit (ECFP-RMLC-Citrine, where ECFP is enhanced cyan fluorescent protein), that detects RMLC phosphorylation using fluorescence resonance energy transfer between two variants of the green fluorescent protein fused to both the N- and C-termini of RMLC. When expressed in primary cultured vascular smooth-muscle cells, CRCit detected the Ca2+-dependent RMLC phosphorylation with a high spatiotemporal resolution. Furthermore, we could specifically assay the agonist-induced Ca2+-independent phosphorylation of RMLC when Ca2+ signalling in cells expressing CRCit was suppressed. Thus CRCit may also be used for the high throughput screening of compounds that inhibit abnormal smooth-muscle contraction.
Apo2L/TRAIL induction and nuclear translocation of inositol hexakisphosphate kinase 2 during IFN-β-induced apoptosis in ovarian carcinoma
Authors: MORRISON Bei H. , TANG Zhuo , JACOBS Barbara S. , BAUER Joseph A. , LINDNER Daniel J.
Published: January 2005

Previously, we have reported that overexpression of IHPK2 (inositol hexakisphosphate kinase 2) sensitized NIH-OVCAR-3 ovarian carcinoma cell lines to the growth-suppressive and apoptotic effects of IFN-β (interferon-β) treatment and γ-irradiation. In the present study, we demonstrate that Apo2L/TRAIL (Apo2L/tumour-necrosis-factor-related apoptosis-inducing ligand) is a critical mediator of IFN-induced apoptosis in these cells. Compared with IFN-α2, IFN-β is a more potent inducer of Apo2L/TRAIL and IHPK2 activity. Overexpression of IHPK2 converts IFN-α2-resistant cells into cells that readily undergo apoptosis in response to IFN-α2. In untreated cells transfected with IHPK2-eGFP (where eGFP stands for enhanced green fluorescent protein), the fusion protein is localized to the cytoplasm and perinuclear region. After treatment with IFN-β, IHPK2-eGFP translocated to the nucleus. In cells transfected with mutant IHPK2-NLS-eGFP (where NLS stands for nuclear localization sequence), containing point mutations in the NLS, the fusion protein remained trapped in the cytoplasm, even after IFN-β treatment. Cells expressing mutant NLS mutation were more resistant to IFN-β. The IC50 value of IHPK2-expressing cells was 2–3-fold lower than vector control. The IC50 value of NLS-mutant-expressing cells was 3-fold higher than vector control. Blocking antibodies to Apo2L/TRAIL or transfection with a dominant negative Apo2L/TRAIL receptor (DR5Δ) inhibited the antiproliferative effects of IFN-β. Thus overexpression of IHPK2 enhanced apoptotic effects of IFN-β, and expression of the NLS mutant conferred resistance to IFN-β. Apo2L/TRAIL expression and nuclear localization of IHPK2 are both required for the induction of apoptosis by IFN-β in ovarian carcinoma.
Proteasome-mediated effects on amyloid precursor protein processing at the γ-secretase site
Authors: FLOOD Fiona , MURPHY Suzanne , COWBURN Richard F. , LANNFELT Lars , WALKER Brian , JOHNSTON Janet A.
Published: January 2005

Aβ (β-amyloid) peptides are found aggregated in the cortical amyloid plaques associated with Alzheimer's disease neuropathology. Inhibition of the proteasome alters the amount of Aβ produced from APP (amyloid precursor protein) by various cell lines in vitro. Proteasome activity is altered during aging, a major risk factor for Alzheimer's disease. In the present study, a human neuroblastoma cell line expressing the C-terminal 100 residues of APP (SH-SY5Y-SPA4CT) was used to determine the effect of proteasome inhibition, by lactacystin and Bz-LLL-COCHO (benzoyl-Leu-Leu-Leu-glyoxal), on APP processing at the γ-secretase site. Proteasome inhibition caused a significant increase in Aβ peptide levels in medium conditioned by SH-SY5Y-SPA4CT cells, and was also associated with increased cell death. APP is a substrate of the apoptosis-associated caspase 3 protease, and we therefore investigated whether the increased Aβ levels could reflect caspase activation. We report that caspase activation was not required for proteasome-inhibitor-mediated effects on APP (SPA4CT) processing. Cleavage of Ac-DEVD-AMC (N-acetyl-Asp-Glu-Val-Asp-7-amino-4-methylcoumarin), a caspase substrate, was reduced following exposure of SH-SY5Y-SPA4CT cells to lactacystin, and co-treatment of cells with lactacystin and a caspase inhibitor [Z-DEVD-FMK (benzyloxycarbonyl-Val-Ala-DL-Asp-fluoromethylketone)] resulted in higher Aβ levels in medium, augmenting those seen with lactacystin alone. This study indicated that proteasome inhibition could increase APP processing specifically at the γ-secretase site, and increase release of Aβ, in the absence of caspase activation. This indicates that the decline in proteasome function associated with aging would contribute to increased Aβ levels.
Hepatitis A virus proteinase 3C binding to viral RNA: correlation with substrate binding and enzyme dimerization
Authors: PETERS Hannelore , KUSOV Yuri Y. , MEYER Sonja , BENIE Andrew J. , BÄUML Englbert , WOLFF Maike , RADEMACHER Christoph , PETERS Thomas , GAUSS-MÜLLER Verena
Published: January 2005

Proteinase 3C of hepatitis A virus (HAV) plays a key role in the viral life cycle by generating mature viral proteins from the precursor polyprotein. In addition to its proteolytic activity, 3C binds to viral RNA, and thus influences viral genome replication. In order to investigate the interplay between proteolytic activity and RNA binding at the molecular level, we subjected HAV 3C and three variants carrying mutations of the cysteine residues [C24S (Cys-24→Ser), C172A and C24S/C172A] to proteolysis assays with peptide substrates, and to surface plasmon resonance binding studies with peptides and viral RNA. We report that the enzyme readily forms dimers via disulphide bridges involving Cys-24. Dissociation constants (KD) for peptides were in the millimolar range. The binding kinetics for the peptides were characterized by kon and koff values of the order of 102 M−1·s−1 and 10−2 to 10−1 s−1 respectively. In contrast, 3C binding to immobilized viral RNA, representing the structure of the 5′-terminal domain, followed fast binding kinetics with kon and koff values beyond the limits of the kinetic resolution of the technique. The affinity of viral RNA depended strongly on the dimerization status of 3C. Whereas monomeric 3C bound to the viral RNA with a KD in the millimolar range, dimeric 3C had a significantly increased binding affinity with KD values in the micromolar range. A model of the 3C dimer suggests that spatial proximity of the presumed RNA-binding motifs KFRDI is possible. 3C binding to RNA was also promoted in the presence of substrate peptides, indicating co-operativity between RNA binding and protease activity. The data imply that the dual functions of 3C are mutually dependent, and regulate protein and RNA synthesis during the viral life cycle.
Lipid phosphate phosphatase-1 regulates lysophosphatidic acid-induced calcium release, NF-κB activation and interleukin-8 secretion in human bronchial epithelial cells
Authors: ZHAO Yutong , USATYUK Peter V. , CUMMINGS Rhett , SAATIAN Bahman , HE Donghong , WATKINS Tonya , MORRIS Andrew , SPANNHAKE Ernst Wm. , BRINDLEY David N. , NATARAJAN Viswanathan
Published: January 2005

LPA (lysophosphatidic acid), a potent bioactive phospholipid, elicits diverse cellular responses through activation of the G-protein-coupled receptors LPA1–LPA4. LPA-mediated signalling is partially regulated by LPPs (lipid phosphate phosphatases; LPP-1, -2 and -3) that belong to the phosphatase superfamily. This study addresses the role of LPPs in regulating LPA-mediated cell signalling and IL-8 (interleukin-8) secretion in HBEpCs (human bronchial epithelial cells). Reverse transcription–PCR and Western blotting revealed the presence and expression of LPP-1–3 in HBEpCs. Exogenous [3H]oleoyl LPA was hydrolysed to [3H]-mono-oleoylglycerol. Infection of HBEpCs with an adenoviral construct of human LPP-1 for 48 h enhanced the dephosphorylation of exogenous LPA by 2–3-fold compared with vector controls. Furthermore, overexpression of LPP-1 partially attenuated LPA-induced increases in the intracellular Ca2+ concentration, phosphorylation of IκB (inhibitory κB) and translocation of NF-κB (nuclear factor-κB) to the nucleus, and almost completely prevented IL-8 secretion. Infection of cells with an adenoviral construct of the mouse LPP-1 (R217K) mutant partially attenuated LPA-induced IL-8 secretion without altering LPA-induced changes in intracellular Ca2+ concentration, phosphorylation of IκB, NF-κB activation or IL-8 gene expression. Our results identify LPP-1 as a key regulator of LPA signalling and IL-8 secretion in HBEpCs. Thus LPPs could represent potential targets in regulating leucocyte infiltration and airway inflammation.
Cloning and characterization of murine 1-acyl-sn-glycerol 3-phosphate acyltransferases and their regulation by PPARα in murine heart
Authors: LU Biao , JIANG Yan J. , ZHOU Yaling , XU Fred Y. , HATCH Grant M. , CHOY Patrick C.
Published: January 2005

AGPAT (1-acyl-sn-glycerol 3-phosphate acyltransferase) exists in at least five isoforms in humans, termed as AGPAT1, AGPAT2, AGPAT3, AGPAT4 and AGPAT5. Although they catalyse the same biochemical reaction, their relative function, tissue expression and regulation are poorly understood. Linkage studies in humans have revealed that AGPAT2 contributes to glycerolipid synthesis and plays an important role in regulating lipid metabolism. We report the molecular cloning, tissue distribution, and enzyme characterization of mAGPATs (murine AGPATs) and regulation of cardiac mAGPATs by PPARα (peroxisome-proliferator-activated receptor α). mAGPATs demonstrated differential tissue expression profiles: mAGPAT1 and mAGPAT3 were ubiquitously expressed in most tissues, whereas mAGPAT2, mAGPAT4 and mAGPAT5 were expressed in a tissue-specific manner. mAGPAT2 expressed in in vitro transcription and translation reactions and in transfected COS-1 cells exhibited specificity for 1-acyl-sn-glycerol 3-phosphate. When amino acid sequences of five mAGPATs were compared, three highly conserved motifs were identified, including one novel motif/pattern KX2LX6GX12R. Cardiac mAGPAT activities were 25% lower (P<0.05) in PPARα null mice compared with wild-type. In addition, cardiac mAGPAT activities were 50% lower (P<0.05) in PPARα null mice fed clofibrate compared with clofibrate fed wild-type animals. This modulation of AGPAT activity was accompanied by significant enhancement/reduction of the mRNA levels of mAGPAT3/mAGPAT2 respectively. Finally, mRNA expression of cardiac mAGPAT3 appeared to be regulated by PPARα activation. We conclude that cardiac mAGPAT activity may be regulated by both the composition of mAGPAT isoforms and the levels of each isoform.
A highly acid-stable and thermostable endo-β-glucanase from the thermoacidophilic archaeon Sulfolobus solfataricus
Authors: HUANG Yiwei , KRAUSS Gerhard , COTTAZ Sylvain , DRIGUEZ Hugues , LIPPS Georg
Published: January 2005

The thermoacidophilic archaeon Sulfolobus solfataricus P2 encodes three hypothetic endo-β-glucanases, SSO1354, SSO1949 and SSO2534. We cloned and expressed the gene sso1949 encoding the 334 amino acids containing protein SSO1949, which can be classified as a member of glycoside hydrolase family 12. The purified recombinant enzyme hydrolyses carboxymethylcellulose as well as cello-oligomers, with cellobiose and cellotriose as main reaction products. By following the hydrolysis of a fluorescently labelled cellohexaoside under a wide variety of conditions, we show that SSO1949 is a unique extremophilic enzyme. This archaeal enzyme has a pH optimum of approx. pH 1.8 and a temperature optimum of approx. 80 °C. Furthermore, the enzyme is thermostable, with a half-life of approx. 8 h at 80 °C and pH 1.8. The thermostability is strongly pH-dependent. At neutral pH, the thermal inactivation rate is nearly two orders of magnitude higher than at pH 1.8. Homology modelling suggests that the catalytic domain of SSO1949 has a similar fold to other mesophilic, acidophilic and neutral cellulases. The presence of a signal peptide indicates that SSO1949 is a secreted protein, which enables S. solfataricus to use cellulose as an external carbon source. It appears that SSO1949 is perfectly adapted to the extreme environment in solfataric pools. A cellulolytic enzyme with such a combination of stability and activity at high temperatures and low pH has not been described so far and could be a valuable tool for the large-scale hydrolysis of cellulose under acidic conditions.
The interaction of carbohydrate-binding modules with insoluble non-crystalline cellulose is enthalpically driven
Authors: BORASTON Alisdair B.
Published: January 2005

Natural cellulose exists as a composite of cellulose forms, which can be broadly characterized as crystalline or non-crystalline. The recognition of both of these forms of cellulose by the CBMs (carbohydrate-binding modules) of microbial glycoside hydrolases is important for the efficient natural and biotechnological conversion of cellulosic biomass. The category of CBM that binds insoluble non-crystalline cellulose does so with an affinity approx. 10–20-fold greater than their affinity for cello-oligosaccharides and/or soluble polysaccharides. This phenomenon has been assumed to originate from the effects of changes in configurational entropy upon binding. The loss of configurational entropy is thought to be less profound upon binding to conformationally restrained insoluble non-crystalline cellulose, resulting in larger free energies of binding. However, using isothermal titration calorimetry, it is shown that this is not the case for the high-affinity interactions of CcCBM17 (the family 17 CBM from EngF of Clostridium cellulovorans) and BspCBM28 (the family 28 CBM from Cel5A of Bacillus species 1139) with regenerated cellulose, an insoluble preparation of primarily non-crystalline cellulose. The enhanced free energy of binding of non-crystalline cellulose relative to cello-oligosaccharides is by virtue of improved enthalpy, not entropy.
Characterization of the conduction phase of a plasma opening switch using a hydrogen plasma
Authors: Moschella J. J. , Klepper C. C. , Vidoli C. , Yadlowsky E. J. , Weber B. V. , Commisso R. J. , Black D. C. , Moosman B. , Stephanakis S. J. , Hinshelwood D. D. , Maron Y.
Published: January 2005

Plasma opening switch (POS) experiments were conducted on the Hawk generator using an inverse pinch plasma source to inject a hydrogen plasma. Using a combination of interferometry, current measurements, and spectroscopic observations, it is shown that the conduction phase is characterized by the propagation of a current channel through the switch region that pushes a significant fraction of the plasma mass downstream, past the load edge of the switch. The data indicate that the current channel arrives at the load edge of the switch ≈550ns into the 950-ns-long conduction phase, in agreement with calculations based on J×B displacement. Previously published POS experiments, using multispecies plasmas, observed that a relatively small fraction of the injected plasma mass propagated downstream and that the conduction phase ended soon after the current channel reached the load edge of the switch. It is suggested that the observed differences between these two types of switches involves the separation of ionic species subject to a magnetic force, where the light-ion plasma is pushed ahead of the magnetic field front and the heavier-ion plasma is penetrated by the field. Species-separation effects may be important in a multispecies POS but would be negligible in this almost pure (>95%) proton-plasma experiment. While the important role of the plasma composition in pulsed magnetic field plasma interactions has been pointed out in previous experimental studies, this work demonstrates that the plasma composition can have a significant effect on the conduction time of a POS.
Stabilization of sawtooth oscillations by the circulating energetic ions
Authors: Kolesnichenko Ya. I. , Marchenko V. S. , White R. B.
Published: January 2005

The influence of the well-circulating energetic ions on the ideal kink instability and the m=1 tearing instabilities (collisionless and semicollisional modes) is studied. It is found that the precession of these ions can be by an important stabilizing factor, especially when the balanced tangential neutral beam injection is used and/or in the presence of fusion-produced α particles.
Miniature focal plane mass spectrometer with 1000-pixel modified-CCD detector array for direct ion measurement
Authors: Sinha Mahadeva P. , Wadsworth Mark
Published: January 2005

A high performance, focal plane miniature mass spectrometer (MMS) of Mattauch–Herzog geometry with a CCD-based array detector for the direct and simultaneous measurements of different mass ions is described. Miniaturization (10cm×5cm×5cm,395g) was accomplished by using high-energy-product magnet material (Nd–B–Fe alloy) and a high permeability yoke material (V–Co–Fe Alloy) for the fabrication of the magnetic sector. The electrostatic sector was machined from a single piece of machinable ceramic (MACOR). All the components of the analyzer are mounted on a single plate, which facilitate their alignment and make the instrument rugged. The modified-CCD based ion detector array has 1000 elements (20μm×2mm) and was invented in our laboratory. The photosensitive part of the CCD was replaced with a metal-oxide-semiconductor (MOS) capacitor for ion detection. The ion sensing capacitor plates are connected to the CCD gates that are operated in the fill-and spill mode providing a gain in the charge domain for the signal ions and minimizing various noises during measurements. The results reported in this article are the first application of this detector array for direct ion measurement and successfully prove the new technology. The MMS with the array detector can measure masses up to 250u with a unit mass resolution and expected to possess a sensitivity of detecting ∼5ions. The above attributes make MMS suitable for space applications for isotopic and chemical analysis and also for field applications on earth.
Short wavelength ion temperature gradient instability in toroidal plasmas
Authors: Gao Zhe , Sanuki H. , Itoh K. , Dong J. Q.
Published: January 2005

Series of ion temperature gradient (ITG or ηi) driven modes in the short wavelength region, ∣k⊥ρi∣>1, are investigated with a gyrokinetic integral equation code in toroidal plasmas. These instabilities exist even if electrons are assumed adiabatic. However, nonadiabatic electron response can influence these short wavelength ITG (SWITG) modes, especially the fundamental l=0 mode. At typical parameters, excitation of the l=0 mode requires that both ηi and ηe exceed thresholds, while the l=1 and l=2 modes with higher harmonic eigenfunctions persist unstable even at ηe=0. Dependence of the SWITG modes on other parameters is also investigated. The l=1 mode with an odd potential eigenfunction grows faster than the l=0 mode and may be dominant in low ηe, high β, weak positive magnetic shear, and/or weak toroidicity regions.
Automatic system to relock a laser frequency to a Fabry–Perot cavity
Authors: Lee Seung Koo , Han Byoung Woong , Cho D.
Published: January 2005

We developed a system that allowed us to unlock and at a later time automatically relock a laser frequency to a medium-finesse Fabry–Perot cavity. The system can work as a chopping wheel or a shutter for a laser field built inside a cavity. The heart of our system is the flywheel circuit for the slower-acting servo loop and the automatic gain control circuit for the faster-acting servo loop. The flywheel circuit stores a correction for a slow frequency drift so that during the unlocked period the slow loop can be safely turned off. The automatic gain control lowers the fast loop gain during a relock process and increases the gain after the lock is secured. The system works reliably at a chopping frequency up to 70Hz, and relocks well after being unlocked for up to 10s.
Collimated, single-pass atom source from a pulsed alkali metal dispenser for laser-cooling experiments
Authors: Moore Kevin L. , Purdy Thomas P. , Murch Kater W. , Leslie Sabrina , Gupta Subhadeep , Stamper-Kurn Dan M.
Published: January 2005

We have developed an improved scheme for loading atoms into a magneto-optical trap (MOT) from a directed rubidium alkali metal dispenser in <10−10Torr ultrahigh vacuum conditions. A current-driven dispenser was surrounded with a cold absorbing “shroud” held at ⩽0°C, pumping rubidium atoms not directed into the MOT. This nearly eliminates background atoms and reduces the detrimental rise in pressure normally associated with these devices. The system can be well-described as a current-controlled, rapidly switched, two-temperature thermal beam, and was used to load a MOT with 3×108atoms.
Laser based synchrotron radiation
Authors: Phuoc Kim Ta , Burgy Fréderic , Rousseau Jean-Philippe , Malka Victor , Rousse Antoine , Shah Rahul , Umstadter Donald , Pukhov Alexander , Kiselev Sergei
Published: January 2005

Beams of x rays in the kiloelectronvolt energy range have been produced from laser-matter interaction. Here, energetic electrons are accelerated by a laser wakefield, and experience betatron oscillations in an ion channel formed in the wake of the intense femtosecond laser pulse. Experiments using a 50 TW laser (30 fs duration) are described, as well as comparisons with numerical simulations. These results pave the way of a new generation of radiation in the x-ray spectral range, with a high collimation and an ultrafast pulse duration, produced by the use of compact laser system.
Distribution of electrically active defects in chemical vapor deposition diamond: Model and measurement
Authors: Balducci A. , Marinelli Marco , Milani E. , Morgada M. E. , Pucella G. , Rodriguez G. , Tucciarone A. , Verona-Rinati G. , Angelone M. , Pillon M.
Published: January 2005

Defects limiting the movement of charge carriers in polycrystalline chemical vapor deposition (CVD) diamond films are located within the grains or in grain boundaries. Their geometrical distribution in the sample is different and is usually unknown. We present here a method to quantitatively evaluate the concentration and distribution of in-grain and grain-boundary located active carrier traps. Since the impact of these two kinds of defects on the performance of CVD diamond based devices is different, it is possible to obtain the defect distribution by measuring the response of diamond alpha particle detectors as a function of film thickness. The Hecht theory, describing the efficiency of a semiconductor particle detector, has been modified to take into account the polycrystalline nature of CVD diamond. This extended Hecht model was then used to fit experimental data and extract quantitative information about the defect distribution.
High-Q whispering-gallery modes in GaAs∕AlOx microdisks
Authors: Peter E. , Sagnes I. , Guirleo G. , Varoutsis S. , Bloch J. , Lemaître A. , Senellart P.
Published: January 2005

We report on the fabrication of microdisks on an AlOx pedestal. We develop a process using electron beam lithography, a chemical etching, and selective oxidation. InAs self-assembled quantum dots are used as a broad band source to probe the optical modes of the microdisks. With this process, we observe whispering-gallery modes, with quality factors as large as 12 500 for 2-μm-diam microdisks.
Nonlinear dielectric spectroscopy of live cells using superconducting quantum interference devices
Authors: Nawarathna D. , Claycomb J. R. , Miller J. H. , Benedik M. J.
Published: January 2005

Magnetic detection of the nonlinear response of cell suspensions to oscillating electrical fields is reported. It has been shown that H+-ATPase, which is located in plasma membrane of yeast cells, generates harmonics of the fundamental frequency when electrically excited at certain frequencies and field strengths. Electrode polarization may cause erroneous results, especially when using a conventional four-probe setup. In this letter we use highly sensitive superconducting quantum interference device magnetometers to detect the cells’ nonlinear response and to avoid electrode polarization effects. Experiments were carried out using yeast (Saccharomyces cerevisiae, 108cells∕ml) cells with excitation voltages and frequencies between 1–5V∕cm and 10–300 Hz, respectively.
Y
1
-
x
Eu
x
Ca
4
O
(
BO
3
)
3
thin film as a luminescent material screened by the combinatorial method
Authors: Sano Hiroyuki , Matsumoto Takahiro , Matsumoto Yuji , Koinuma Hideomi
Published: January 2005

A phosphor material, Y1-xEuxCa4O(BO3)3 (0⩽x⩽1) film, was fabricated on SiO2 substrates by the combinatorial laser molecular-beam epitaxy method. Photoluminescence (PL) and PL decay were measured for this film library to identify the optimum composition as well as to determine the luminescence mechanism. Results showed that the observed intense emission peak at 615nm originated from the electric dipole D05→F27 transition of Eu3+. This strong emission makes this red phosphor particularly applicable in devices such as plasma display panels and Xe lamps.
Nanometer scale patterning using focused ion beam milling
Authors: Petit D. , Faulkner C. C. , Johnstone S. , Wood D. , Cowburn R. P.
Published: January 2005

We report on the performance of focused ion beam (FIB) milling in order to produce nanometer scale devices. Resolution issues have been systematically studied as a function of emission current and working distance, by imaging single pixel lines FIB milled into thin bismuth films deposited on oxidized silicon. The ion beam profile has been measured, and by carefully optimizing the milling conditions, 40nm Hall probe sensors have been fabricated.
Investigation of physical and electric properties of silver pastes as a binder for thermoelectric materials
Authors: Suzuki Atsushi , Hasegawa Yasuhiro , Ishikawa Yoshiaki , Komine Takashi , Morita Hiroyuki , Shirai Hajime
Published: January 2005

The physical and electric properties of several silver pastes, Pb-Sn solder, and indium were systematically investigated as potential binders for attaching electrodes to bismuth-based bulk or nanowire array thermoelectric elements. Scanning electron microscopy observations and x-ray diffraction surface measurements of the silver pastes were performed and the temperature and magnetic field dependence of the resistance were measured to characterize their electrical properties from 300K down to 15K and from 0to1T at 15K, respectively. The silver pastes were not reactive with bismuth and hence were found to be potentially useful as electrically conductive adhesives with bismuth-based materials. The properties of each of the binders were quite different; the typical size of the particles in the silver pastes before solidification were distributed in the range from 3nmto20μm, and the size strongly affected the resistances of the silver pastes, which were distributed over 2 and 3 orders of magnitude at 300 and 15K, respectively. Therefore, an appropriate selection of binder must be made for a specific purpose, based on the measurement results. For use with bismuth-based thermoelectric materials, the silver nanopaste is a strong candidate binder because it is far superior to other the binders examined in terms of its resistance properties and magnetic field dependence.
Self-assembly of protein at aqueous solution surface in correlation to protein crystallization
Authors: Jia Yanwei , Liu Xiang-Yang
Published: January 2005

The assembly of lysozyme (hen egg white) at the surface of aqueous solution follows the same behaviors as amphiphilic molecules. The critical assembly concentration appearing in the protein solutions is found to coincide with the equilibrium concentration of protein crystals under given conditions. The crystallization of protein regarded as a typical case of protein self-assembly in three dimensions has been discussed. The result reveals also the correlation between protein crystallization and the two-dimensional self-assembly at the surface of substrates. It follows that the protein crystallization condition can be determined without protein crystals.
Fluid pumped by magnetic stress
Authors: Krauß Robert , Reimann Bert , Richter Reinhard , Rehberg Ingo , Liu Mario
Published: January 2005

A magnetic field rotating on the free surface of a ferrofluid layer is shown to induce considerable fluid motion toward the direction the field is rolling. The measured flow velocity (i) increases with the square of the magnetic field amplitude, (ii) is proportional to the thickness of the fluid layer, and (iii) has a maximum at a driving frequency of about 3kHz. The pumping speed can be estimated with a two-dimensional flow model.
Collective effects on the symmetric resonant charge transfer in partially ionized hydrogen plasma
Authors: Jung Young-Dae
Published: January 2005

The collective nonideal effects on the symmetric resonant charge transfer process in the intermediate velocity region are investigated in partially ionized hydrogen plasmas. The effective pseudopotential model taking into account the plasma screening and collective effects is applied to describe the interaction potential in nonideal plasmas. The electron transfer probability and cross section are obtained as functions of the energies of the symmetric and antisymmetric stationary states, nonideality plasma parameter, Debye length, and collision velocity. The results show that the collective effects enhance the symmetric resonant electron transfer probability as well as the electron transfer cross section in nonideal plasmas. It is also found that the collective effects on the symmetric resonant charge transfer process are more significant than the screening effects in nonideal plasmas.
Ballistic transport mode detected by picosecond time-of-flight measurements for nanocrystalline porous silicon layer
Authors: Kojima Akira , Koshida Nobuyoshi
Published: January 2005

The electron transport mechanism in nanocrystalline porous silicon (nc-PS) with a controlled structure has been studied for a self-supporting sample by time-of-flight (TOF) measurements at room and low temperatures using a picosecond-width UV laser pulse. In contrast to both single-crystalline silicon (c-Si) and hydrogenated amorphous silicon (a-Si:H), the TOF signals of nc-PS show characteristic behavior that involves a ballistic component. The drift velocity vd determined from observed TOF signals shows no signs of saturation with increasing field strength F. At F∼3×104V∕cm, the vd value in nc-PS at room temperature reaches 2.2×108cm∕s. The corresponding electron mean free path is 1.6μm. These values are considerably larger than those in c-Si. The ballistic transport mode becomes clear at low temperatures. The results support the model that electrons can travel ballistically with little scattering losses in a nanocrystalline silicon dot chain interconnected via thin silicon dioxide films.
Ion energy uniformity in high-frequency capacitive discharges
Authors: Perret A. , Chabert P. , Jolly J. , Booth J.-P.
Published: January 2005

Ion energy distribution functions and ion fluxes in low-pressure, high-frequency (13.56–80MHz) capacitive discharges were investigated both theoretically and experimentally. In most of the conditions explored, the ion energy distribution function was a single peak centered at the time-averaged plasma potential. Lower energy ions with higher fluxes are obtained as the frequency increases. The uniformity of the ion energy across large-area electrodes (40cm2) was also studied in conditions under which the standing wave effect is important, i.e., conditions such that the rf voltage and the ion flux are strongly nonuniform. Unlike the latter quantities, the ion energy was uniform across the reactor at all frequencies, due to dc current flowing radially in the plasma and in the electrodes.
Laser induced fluorescence in a pulsed argon plasma
Authors: Scime Earl , Biloiu Costel , Compton Christopher , Doss Forrest , Venture Daniel , Heard John , Choueiri Edgar , Spektor Rostislav
Published: January 2005

A time-resolved laser induced fluorescence (LIF) technique for pulsed argon plasmas is described. A low power, tunable diode laser pumps a three level Ar II transition sequence at a wavelength of 668.6138 nm. With a standard LIF system designed for steady-state plasmas (e.g., 4 kHz optical chopper, 20 kHz band-width detector, and a lock-in amplifier), we demonstrate that the evolution of the ion velocity distribution can be resolved with a time resolution of 1 ms through a combination of time-series averaging and post-acquisition digital signal processing.
Nanoscale surface domain formation on the +z face of lithium niobate by pulsed ultraviolet laser illumination
Authors: Valdivia C. E. , Sones C. L. , Scott J. G. , Mailis S. , Eason R. W. , Scrymgeour D. A. , Gopalan V. , Jungk T. , Soergel E. , Clark I.
Published: January 2005

Single-crystal congruent lithium niobate samples have been illuminated on the +z crystal face by pulsed ultraviolet laser wavelengths below (248nm) and around (298–329nm) the absorption edge. Following exposure, etching with hydrofluoric acid reveals highly regular precise domain-like features of widths ∼150–300nm, exhibiting distinct three-fold symmetry. Examination of illuminated unetched areas by scanning force microscopy shows a corresponding contrast in piezoelectric response. These observations indicate the formation of nanoscale ferroelectric surface domains, whose depth has been measured via focused ion beam milling to be ∼2μm. We envisage this direct optical poling technique as a viable route to precision domain-engineered structures for waveguide and other surface applications.