bluuebunny/crossref_metadata_2025 huggingface dataset:
Nutritional support via percutaneous endoscopic gastrostomy in children with cardiac disease experiencing difficulties with feeding
Authors: Ciotti Giovanna , Holzer Ralf , Pozzi Marco , Dalzell Mark
Published: August 2006

Adequate nutrition is crucial to the management of children and infants with cardiac disease. Difficulties with feeding are extremely common, and maintaining an adequate caloric intake, in order to achieve sustained growth, is often not possible without nutritional support. We retrospectively reviewed our experience between 1995 and 1999 in treating 37 children with cardiac disease who underwent percutaneous endoscopic construction of a gastrostomy to augment nutritional needs. We stratified the patients into those with cyanotic heart disease, when saturations of oxygen were less than 95%; those with non-cyanotic heart disease with saturations greater than 95%, and those with minor cardiac disease associated with a systemic disorder. Each group was compared to control children matched for age, sex, and diagnosis. We evaluated the variation in standard deviation score for body weight over a median period of follow-up of 295 days. Improvements in the standard deviation score for body weight occurred in each of the groups, whereas children in the control groups demonstrated a decrease in standard deviation score for body weight. The median change of the score for body weight was significantly higher in patients managed with gastrostomy compared to controls. We conclude that supplementation using a gastrostomy tube allows the safe delivery of the caloric intake needed to support malnourished children with cardiac disease.
Radiofrequency ablation of atrioventricular accessory pathways associated with discordant atrioventricular connections
Authors: Iturralde Pedro , Rivera-Rodríguez Leonardo , Guevara-Valdivia Milton E. , Colín Luis , Márquez Manlio F. , Calvimontes Gonzalo
Published: August 2006

Discordant atrioventricular connections associated with Wolff-Parkinson-White syndrome increase the challenge of radiofrequency ablation. We report the results and techniques of radiofrequency ablation in three patients with discordant atrioventricular connections, including one patient having double outlet right ventricle with atrioventricular reentry tachycardias. There were two males and one female, aged 14 and 22 years old. We found four accessory pathways during our electrophysiological studies, with two of them manifest on the electrocardiogram, corresponding to left paraseptal and right midseptal regions. The electrophysiological study confirmed this localization, and showed two concealed accessory pathways in the right and left paraseptal regions. Radiofrequency ablation was successful in all cases without recurrence at a mean follow-up of 18.6 months. No complications were observed during the procedures. We conclude that radiofrequency ablation is feasible and effective in the ablation of accessory pathways in patients with discordant atrioventricular connections.
Hearing Kaleidoscopes: Embedded Grouping Dissonance in Electronic Dance Music
Authors: BUTLER MARK J.
Published: August 2006

The rhythmic and metrical qualities of electronic dance music (EDM) are clearly among its most prominent and appreciated features. Yet scholarship on rhythm, as well as popular discourse surrounding EDM, often frames the pervasively duple metres that characterize popular dance-based styles as simplistic and limited in capacity. Given the allure of EDM’s temporal qualities, how do musicians devise creative solutions to the constraints of its duple metrical organization? This article addresses this question through a consideration of embedded grouping dissonance, one of several distinctive rhythmic phenomena found in EDM. In theorizing embedded grouping dissonance, the article both builds upon and expands recent music-theoretical formulations of ‘metrical dissonance’, which describe similar occurrences without addressing this specific phenomenon. It then situates embedded grouping dissonance in relation to EDM’s technologically mediated means of production, arguing that this rhythmic technique exemplifies recurring principles of design that shape and reflect the aesthetics of electronic dance music on a broad scale.
Richard Steinitz, György Ligeti: Music of the Imagination (London: Faber and Faber, 2003), ISBN 0 571 17631 3 (hb)
Authors: Bauer Amy
Published: August 2006

Hungarian composer György Ligeti has not lacked for attention since coming into contact with Europe’s new music scene in the early 1960s. In 1966 he was featured in Moderne Musik I: 1945–65, and by 1969 Erkki Salmenhaara had published a dissertation on three major works. Although periodic illness and a painstaking approach to composition slowed his progress, Ligeti continued to refine and expand his style in the 1970s, producing everything from intimate solo works for harpsichord to the suitably grand opera Le Grand Macabre (1974–7, revised 1996). His turn towards traditional orchestral forms and a quasi-diatonic language in the 1980s brought him new prominence, and the voluble composer has seemed ever ready to provide ripe commentary on his work and the state of new music. The numerous awards and publications that followed Ligeti’s seventieth birthday in 1993 support his status as probably the most widely fêted and influential composer of the latter half of the twentieth century. And if that degree of timely recognition was not enough, the composer has entered his ninth decade with no noticeable decline in compositional energy or ideas. Ligeti continues to fashion brilliant revisions of the tried but true genres of concerto, solo étude, song cycle, choral work, and character piece. His compositions bear the weight of extramusical influence as well as that from beyond the Western canon, yet each innovation affirms his inimitable voice and his singular musical journey from the mid-twentieth to the twenty-first century.
Development of a Highly Productive and Scalable Plasmid DNA Production Platform
Authors: Listner K. , Bentley L. , Okonkowski J. , Kistler C. , Wnek R. , Caparoni A. , Junker B. , Robinson D. , Salmon P. , Chartrain M.
Published: August 2006

With the applications of DNA vaccines extending from infectious diseases to cancer, achieving the most efficient, reproducible, robust, scalable, and economical production of clinical grade plasmid DNA is paramount to the medical and commercial success of this novel vaccination paradigm. A first generation production process based on the cultivation of Escherichia coli in a chemically defined medium, employing a fed‐batch strategy, delivered reasonable volumetric productivities (500–750 mg/L) and proved to perform very well across a wide range of E. coli constructs upon scale‐up at industrial scale. However, the presence of monosodium glutamate (MSG) in the formulation of the cultivation and feed solution was found to be a potential cause of process variability. The development of a second generation process, based on a defined cultivation medium and feed solution excluding MSG, was undertaken. Optimization studies, employing a plasmid coding for the HIV gag protein, resulted in cultivation conditions that supported volumetric plasmid titers in excess of 1.2 g/L, while achieving specific yields ranging from 25 to 32 μg plasmid DNA/mg of dry cell weight. When used for the production of clinical supplies, this novel process demonstrated applicability to two other constructs upon scale‐up in 2,000‐L bioreactors. This second generation process proved to be scalable, robust, and highly productive.
Children of Latino Immigrants, 4-8 Years, in Rural Nebraska are Adequate in Vitamin B-6
Authors: Lora Karina R. , Giraud David W. , Davy Sarah R. , Driskell Judy A.
Published: August 2006

Plasma concentrations of B-6 vitamers and homocysteine as well as erythrocyte alanine aminotransferase activity coefficients and vitamin B-6 (dietary + supplement) intakes of apparently healthy young Latino children of immigrant parents living in rural Nebraska were determined and differences determined by gender. Thirty-five Latino children (16 males and 19 females), aged 4–8 years, were included in the study. Nutrient intake information was obtained from the children’s parents utilizing two nonconsecutive 24-hour food recalls. No differences were observed by gender with regard to vitamin B-6 intakes, plasma concentrations of B-6 vitamers and homocysteine, and erythrocyte alanine aminotransferase activity coefficients. The intakes of all children met the Recommended Dietary Allowance for vitamin B-6. Plasma pyridoxal 5’-phosphate concentrations, plasma homocysteine concentrations, and erythrocyte alanine aminotransferase activity coefficients of the children were (mean ± SD) 83.71 ± 37.35 nmol/L, 6.81 ± 1.63 µmol/L, and 1.08 ± 0.06, respectively. All the Latino children of immigrant parents in this study had values indicative of adequate vitamin B-6 status.
Chitosan Shifts the Fermentation Site Toward the Distal Colon and Increases the Fecal Short-Chain Fatty Acids Concentrations in Rats
Authors: Yao Hsien-Tsung , Chiang Meng-Tsan
Published: August 2006

Chitosan has been shown to have lipid-lowering effects, but little is known about the effect of chitosan on colonic pH value and short-chain fatty acid (SFCA) concentration. This study was designed to investigate the effect of chitosan on colonic bacterial fermentation and fecal bacterial enzyme activity in rats fed a diet enriched in cholesterol. Male Sprague-Dawley rats were fed a diet containing 5% cellulose (CE) or 5% chitosan (CS) for 15 days. Significantly increased fecal cholesterol and triacylglycerols contents were observed in rats fed the chitosan diet. In addition, lower cecal acetate and butyrate concentrations and higher fecal acetate, propionate, and butyrate concentrations were observed in rats fed the CS diet when compared to those fed the CE diet. Although rats fed with the CS diet exhibited an elevated cecal (cecum with contents) weight and higher pH value, no significant difference in fecal pH value was observed between the CE group and the CS group. Chitosan significantly decreased fecal mucinase and beta-glucuronidase activities. Results from this study show that chitosan may alter fecal bacterial enzyme activities and SCFA concentrations and the beneficial effects of chitosan on the colonic environment may occur in the distal colon in rats.
Dietary Intakes and Plasma 8-Iso-Prostaglandin F2α Concentrations in Community-Dwelling Elderly Japanese: The Tsurugaya Project
Authors: Kuriyama Shinichi , Ebihara Satoru , Hozawa Atsushi , Ohmori Kaori , Kurashima Kayoko , Nakaya Naoki , Matsui Toshifumi , Arai Hiroyuki , Tsubono Yoshitaka , Sasaki Hidetada , Tsuji Ichiro
Published: August 2006

We examined the association between dietary intakes and oxidative stress status in elderly Japanese. We analyzed cross-sectional data from a community-based Comprehensive Geriatric Assessment conducted in 2002. The subjects included 961 Japanese subjects aged 70 years or older who were non-daily antioxidant supplements users. We measured plasma total 8-iso-prostaglandin (PG)F2α concentrations, a measurable lipid peroxidation biomarker, using a specific enzyme immunoassay kit. Dietary intakes were assessed through a food frequency questionnaire. Subjects were divided into three groups according to their dietary intake frequencies. Logistic regression was applied to calculate the odds ratios (ORs) for being in the highest tertile of plasma 8-iso-PGF2α concentration. Frequent intake of orange or other citrus fruits, or persimmon, strawberry, or kiwi fruit was associated with lower plasma 8-iso-PGF2α concentrations, respectively. After adjustment for potential confounders, the ORs and 95% confidence intervals (CIs) for orange or other citrus fruits were 1.00 (reference), 0.66 (0.47, 0.92), and 0.58 (0.39, 0.87) (p for trend, 0.009). Intake of persimmon, strawberry, or kiwi fruit showed similar results. These associations were partly explained by vitamin C intake. Other dietary intakes had no association. Intake of fruits may have a beneficial effect against oxidative stress in elderly Japanese.
Effects of a Nutritional Supplement Fortified with Vitamin B-12 on Well Nourished, Free-Living Elderly Subjects
Authors: Hirsch Sandra , Leiva Laura , de la Maza Pía , Gattás Vivian , Barrera Gladys , Hertrampf Eva , Bunout Daniel
Published: August 2006

Vitamin B-12 deficiency is prevalent among the elderly population but it is often unrecognized because the clinical manifestations are not present. Objective: To evaluate the effects of a nutritional supplement fortified with vitamin B-12 on well nourished, free-living elderly subjects. Patients and methods: Healthy elderly subjects attending two of four clinics were allocated to receive, over six months’ duration, a nutritional supplement with 3.8 µg of vitamin B-12. Subjects attending the other two clinics served as controls. Serum vitamin B-12 levels were measured at baseline and 6 months after the supplementation was started. Results: After 6 months of consuming the supplement fortified with vitamin B-12, serum B-12 concentration increased from 350.1 ± 166.5 pmol/L to 409.0 ± 166.1 and decreased in the control group from 319.4 ± 129.1 to 290.1 ± 135.7 (ANOVA, p < 0.005). Conclusion: A supplementation with 3.8 µg /day of vitamin B-12 led to significant improvements in the serum concentrations of vitamin B-12 in older persons.
Oxygen isotope ecology of recent planktic foraminifera at the central Walvis Ridge (SE Atlantic)
Authors: Lončarić Neven , Peeters Frank J. C. , Kroon Dick , Brummer Geert‐Jan A.
Published: August 2006

Above the Walvis Ridge, in the SE Atlantic Ocean, we collected living plantkic foraminifera from the upper water column using depth stratified plantkon tows. The oxygen isotope composition (δ18Oc) in shells of foraminifera and shell concentration profiles show seasonal and depth habitats of individual species. The tow results are compared with the average annual deposition δ18Oc from sediment traps and the interannual average δ18Oc of fossil specimens in top sediments at the same site. The species Globigerinita glutinata best reflects the austral winter/spring sea surface temperature (SST). Its δ18Oc signal in top sediments remains pristine. In contrast, tow results also show that Globigerinoides ruber continues to calcify below the surface mixed layer (SML), i.e., down to the deep chlorophyll maximum (DCM); hence its δ18Oc signature of exported specimens reflects the SST only when SML incorporates the DCM. Deep tow and sediment trap results show that both Globorotalia truncatulinoides and Globorotalia inflata record the temperature between 150 and 350 m, depending on the season and the shell size. However, for all fossil taxa in sediments apart from Globigerinita glutinata, we observe a positive δ18Oc shift with respect to the sediment trap and plankton tow values, likely related to the interannual flux changes and deep encrustation.
Shear wave anisotropy of the northeast Indian lithosphere
Authors: Singh Arun , Kumar M. Ravi , Raju P. Solomon , Ramesh D. S.
Published: August 2006

Analysis of SKS/SKKS phases in the northeast India region provides the first results using digital data, from the southern side of the India‐Asia collision zone. Our analysis reveals detectable anisotropy in the study region, contrary to negligible anisotropy reported in southern Tibet. The direction of anisotropy is E‐W within the Himalaya and its foredeep, N‐S in the Indo‐Burma convergence zone and NE‐SW close to the Shillong plateau. While lithospheric deformation due to finite strain induced by collision seems to be the source of anisotropy in the Himalaya and its foredeep, an asthenospheric source is invoked as a causative for the mantle strain in the plate interior.
Ocean bottom pressure observation off Sanriku and comparison with ocean tide models, altimetry, and barotropic signals from ocean models
Authors: Matsumoto K. , Sato T. , Fujimoto H. , Tamura Y. , Nishino M. , Hino R. , Higashi T. , Kanazawa T.
Published: August 2006

We discuss tidal and non‐tidal signals which are obtained from ocean bottom pressure (OBP) measurements at two sites off Sanriku, Japan. Comparison between the observed tidal component and five ocean tide models shows that recent models have accuracy better than 1.3 cm in terms of root sum square of vector differences for eight principal constituents. The empirical estimates of non‐tidal signal from TOPEX/POSEIDON (T/P) and JASON‐1 deviate from barotropic signals observed by OBP recorders, which can be attributed to baroclinic component in the altimeter data. We also compared the non‐tidal barotropic signal derived from the observation with those from ECCO model (wind‐driven) and Kyushu University model (pressure‐driven). The comparison indicates that the pressure‐driven model increases explained variance and it is suggested to combine the wind‐driven model and the pressure‐driven model in order to describe non‐tidal ocean mass variability in particular at period shorter than 30 days.
The histone acetyltransferases CBP/p300 are degraded in NIH 3T3 cells by activation of Ras signalling pathway
Authors: Sánchez-Molina Sara , Oliva José Luis , García-Vargas Susana , Valls Ester , Rojas José M. , Martínez-Balbás Marian A.
Published: August 2006

The CBP [CREB (cAMP-response-element-binding protein)-binding protein]/p300 acetyltransferases function as transcriptional co-activators and play critical roles in cell differentiation and proliferation. Accumulating evidence shows that alterations of the CBP/p300 protein levels are linked to human tumours. In the present study, we show that the levels of the CBP/p300 co-activators are decreased dramatically by continuous PDGF (platelet-derived growth factor) and Ras signalling pathway activation in NIH 3T3 fibroblasts. This effect occurs by reducing the expression levels of the CBP/p300 genes. In addition, CBP and p300 are degraded by the 26 S proteasome pathway leading to an overall decrease in the levels of the CBP/p300 proteins. Furthermore, we provide evidence that Mdm2 (murine double minute 2), in the presence of active H-Ras or N-Ras, induces CBP/p300 degradation in NIH 3T3 cells. These findings support a novel mechanism for modulating other signalling transduction pathways that require these common co-activators.
Novel transcripts of Nox1 are regulated by alternative promoters and expressed under phenotypic modulation of vascular smooth muscle cells
Authors: Arakawa Noriaki , Katsuyama Masato , Matsuno Kuniharu , Urao Norifumi , Tabuchi Yoshiaki , Okigaki Mitsuhiko , Matsubara Hiroaki , Yabe-Nishimura Chihiro
Published: August 2006

NADPH oxidase is implicated in the pathogenesis of various cardiovascular disorders. In vascular smooth muscle cells (VSMC), expression of NOX1 (NADPH oxidase 1), a catalytic subunit of NADPH oxidase, is low and is induced upon stimulation by vasoactive factors, while it is abundantly expressed in colon epithelial cells. To clarify the regulatory mechanisms underlying such cell-specific expression, the upstream regions directing transcription of the NOX1 gene were explored. In P53LMACO1 cells, a cell line originated from mouse VSMCs, two novel Nox1 mRNA species, the c- and f-type, were isolated. These transcripts contained 5′-untranslated regions that differed from the colon type mRNA (a-type) and encoded an additional N-terminal peptide of 28 amino acids. When these transcripts were fused to the c-myc tag and expressed in human embryonic kidney 293 cells, a fraction of translated proteins demonstrated the size containing the additional peptide. Proteins encoded by the c- and f-type mRNAs exhibited superoxide-producing activities equivalent to the activity of the a-type form. The a-type mRNA was expressed in the colon and in the intact aorta, whereas the c-type mRNA was detected in the primary cultured VSMCs migrated from aortic explants, in vascular tissue of a wire-injury model and in the thoracic aorta of mice infused with angiotensin II. The promoter region of the c-type mRNA exhibited transcriptional activity in P53LMACO1 cells, but not in MCE301 cells, a mouse colon epithelial cell line. These results suggest that expression of the Nox1 gene is regulated by alternative promoters and that the novel c-type transcript is induced under phenotypic modulation of VSMCs.
Modification of the pulmonary renin–angiotensin system and lung structural remodelling in congestive heart failure
Authors: Lefebvre Frederic , Préfontaine Annick , Calderone Angelino , Caron Alexandre , Jasmin Jean-François , Villeneuve Louis , Dupuis Jocelyn
Published: August 2006

Lung structural remodelling, characterized by myofibroblast proliferation and collagen deposition, contributes to impaired functional capacity in CHF (congestive heart failure). As the lung is the primary site for the formation of Ang II (angiotensin II), local modifications of this system could contribute to lung remodelling. Rats with CHF, induced following myocardial infarction (MI) via coronary artery ligation, were compared with sham-operated controls. The MI group developed lung remodelling as confirmed by morphometric measurements and immunohistochemistry. Pulmonary Ang II concentrations increased more than 6-fold (P<0.01), and AT1 (Ang II type 1) receptor expression was elevated by 3-fold (P<0.01) with evidence of distribution in myofibroblasts. AT2 (Ang II type 2) receptor expression was unchanged. In isolated lung myofibroblasts, AT1 and AT2 receptors were expressed, and Ang II stimulated proliferation as measured by [3H]thymidine incorporation. In normal rats, chronic intravenous infusion of Ang II (0.5 mg·kg−1 of body weight·day−1) for 28 days significantly increased mean arterial pressure (P<0.05), without pulmonary hypertension, lung remodelling or a change in AT1 receptor expression. We conclude that there is a modification of the pulmonary renin–angiotensin system in CHF, with increased Ang II levels and AT1 receptor expression on myofibroblasts. Although this may contribute to lung remodelling, the lack of effect of increased plasma Ang II levels alone suggests the importance of local pulmonary Ang II levels combined with the effect of other factors activated in CHF.
Direct comparison of relaxation and cGMP production in human coronary by-pass grafts in response to stimulation with natriuretic peptides and a nitric oxide donor
Authors: Hammerer-Lercher Angelika , Fersterer Johann , Holzmann Sigrid , Bonatti Johannes , Ruttmann Elfriede , Hoefer Daniel , Mair Johannes , Puschendorf Bernd
Published: August 2006

In the present study, we investigated the vasodilator properties of A-type, B-type and C-type natriuretic peptides (ANP, BNP and CNP respectively) and the NO (nitric oxide) donor sin-1 (3-morpholino-sydnonimine) in human by-pass grafts. In contrast with previous studies, the same vessel was used to demonstrate a direct link between cGMP production and functional relaxation. Remnants of the IMA (internal mammary artery) and SV (saphenous vein) were obtained from 82 patients undergoing coronary artery by-pass grafting. The responses to cumulative concentrations of ANP, BNP, CNP and sin-1 in vessel rings pre-contracted with a thromboxane A2 agonist (U46619) were measured in an organ bath. Additionally, intracellular cGMP production after single submaximal dose application of these drugs to vessel rings was determined by a RIA. ANP (P=0.001) and sin-1 (P<0.001) caused significant concentration-dependent relaxation of the IMA. In the SV, only sin-1 (P<0.001) induced marked concentration-dependent relaxation. At a single submaximal concentration, significant relaxation as well as intracellular cGMP production were found in response to ANP, BNP and sin-1 in the IMA. In contrast, in the SV, only sin-1 significantly induced cGMP production and relaxation. There was a moderate, but significant, correlation between intracellular cGMP net production and net relaxation in the IMA. In conclusion, ANP, as the most powerful relaxant of all the natriuretic peptides tested on the IMA, may be a possible alternative vasorelaxant to overcome peri-operative vasospasm in this artery. In contrast with sin-1, ANP and BNP were not effective vasorelaxants of the SV. Net relaxation in response to natriuretic peptides correlated with cGMP net concentrations in the IMA.
Highly efficient organic light-emitting diodes based on donor-acceptor small molecules
Authors: Oh Jae-Jin , Kim Ki-Won , Kim Min-Sook , Kwon Tae-Woo , Park Dong-Kyu , Cho Seong-Jin , Woo Hyung-Suk
Published: August 2006

The authors have fabricated highly efficient organic light-emitting diodes from donor-acceptor small molecules, 2-(4-methyl-quinolin-2-yl)-10-phenyl-phenothiazine (MQPTZ) and 2-(4-phenyl-quinolin-2-yl)-10-phenyl-phenothiazine (PQPTZ). Their devices turned on at 4.0V and emitted strong green light near 510nm. The maximum luminance of 60 000 and 55000cd∕m2 at 10.4V and the maximum power efficiencies of 5.75 and 2.5lm∕W at 5V were obtained from the MQPTZ and the PQPTZ, respectively. The overall performance of their devices in terms of current-voltage, luminance, and external quantum efficiency were discussed and compared with those from the device with tris-(8-hydroxyquinolineolato) aluminum.
Breakdown phenomena of zirconium-doped hafnium oxide high-k stack with an inserted interface layer
Authors: Luo Wen , Yuan Tao , Kuo Yue , Lu Jiang , Yan Jiong , Kuo Way
Published: August 2006

Two-step breakdown is observed on a zirconium-doped hafnium oxide film with a hafnium silicate interface layer. The high-k stack has an equivalent oxide thickness of ∼1.7nm. It is found that defect accumulation in the interface region triggers breakdown of the stack subjected to gate injection.
Phase stability of epitaxially grown Ti2AlN thin films
Authors: Beckers M. , Schell N. , Martins R. M. S. , Mücklich A. , Möller W.
Published: August 2006

The phase stability of Mn+1AXn phase (M: early transition metal, A: A-group element, and X: C and∕or N) Ti2AlN thin films reactively sputtered onto MgO(111) and Al2O3(0001) substrates has been investigated by in situ x-ray diffraction and Rutherford backscattering. High substrate temperature deposition results in epitaxial Ti2AlN growth with basal planes parallel to the substrate surface. In contrast to reported high thermal stability for bulk Ti–Al–N Mn+1AXn phases in air, Ti2AlN thin films in vacuum decompose already at ∼800°C. The decomposition proceeds by outward Al diffusion and evaporation, followed by detwinning of the as-formed Ti2N atomic layers into cubic TiNx and intermediate phases.
Flexible ferroelectret field-effect transistor for large-area sensor skins and microphones
Authors: Graz Ingrid , Kaltenbrunner Martin , Keplinger Christoph , Schwödiauer Reinhard , Bauer Siegfried , Lacour Stéphanie P. , Wagner Sigurd
Published: August 2006

Ferroelectrets generate an electric field large enough to modulate the conductance of the source-drain channel of a thin-film field-effect transistor. Integrating a ferroelectret with a thin-film transistor produces a ferroelectret field-effect transistor. The authors made such transistors by laminating cellular polypropylene films and amorphous silicon thin-film transistors on polyimide substrates. They show that these ferrroelectret field-effect transistors respond in a static capacitive or dynamic piezoelectric mode. A touch sensor, a pressure-activated switch, and a microphone are demonstrated. The structure can be scaled up to large-area flexible transducer arrays, such as roll-up steerable compliant sensor skin.
ac susceptibility and critical-current densities in sintered YBa2Cu3O7−δ superconductors
Authors: Chen D.-X. , Pardo E. , Sanchez A. , Bartolomé E.
Published: August 2006

The field-amplitude and frequency dependent complex ac susceptibility of a well sintered YBa2Cu3O7−δ disk has been measured at 77K, which shows that its intra- and intergranular critical-current densities are determined by the collective flux creep inside the grains and the maximum Josephson currents across the grain boundaries, respectively. While the former is widely recognized, the latter contrasts to a popular belief of a mechanism of Josephson-vortex pinning and creep.
Visible two-dimensional photonic crystal slab laser
Authors: Zhang Zhaoyu , Yoshie Tomoyuki , Zhu Xiaoliang , Xu Jiajing , Scherer Axel
Published: August 2006

The authors describe the fabrication and performance of photonic crystal lasers fabricated within thin membranes of InGaP∕InGaAlP quantum well material and emitting in the visible wavelength range. These lasers have ultrasmall mode volumes, emit red light, and exhibit low threshold powers. They can be lithographically tuned from 650to690nm. Their cavity volumes of approximately 0.01μm3 are ideally suited for use as spectroscopic sources.
Projective measurement in nuclear magnetic resonance
Authors: Lee Jae-Seung , Khitrin A. K.
Published: August 2006

It is demonstrated that nuclear magnetic resonance experiments using pseudopure spin states can give possible outcomes of projective quantum measurement and probabilities of such outcomes. The physical system is a cluster of six dipolar-coupled nuclear spins of benzene in a liquid-crystalline matrix. For this system with the maximum total spin S=3, the results of measuring SX are presented for the cases when the state of the system is one of the eigenstates of SZ.
Traveling-wave photomixers fabricated on high energy nitrogen-ion-implanted GaAs
Authors: Mikulics M. , Michael E. A. , Marso M. , Lepsa M. , van der Hart A. , Lüth H. , Dewald A. , Stanček S. , Mozolik M. , Kordoš P.
Published: August 2006

The authors report on fabrication and measurement of traveling-wave photomixers based on high energy and low dose nitrogen-ion-implanted GaAs. They used 3MeV energy to implant N+ ions into GaAs substrates with an ion concentration dose of 3×1012cm−2. The N+-implanted GaAs photomixers exhibit improvements in the output power in comparison with their counterparts, photomixers fabricated on low-temperature-grown GaAs. The maximal output power was 2.64μW at 850GHz. No saturation of the output power with increased bias voltage and optical input power was observed. These characteristics make N+-implanted GaAs the material of choice for efficient high power sources of terahertz radiation.
Females, but Not Males, Show Greater Pupillary Response to Direct-Than Deviated-Gaze Faces
Authors: Porter Gillian , Hood Bruce M , Troscianko Tom , Macrae C Neil
Published: August 2006

Under suitable conditions, pupillary dilation is a reliable index of processing activity. Pupil size was tracked in male and female observers following the presentation of face stimuli for an age-judgment task. The eyes on the faces were either directed towards the observer or deviated to the side. Pupil dilation accompanied processing of the faces, but female observers showed significantly more sustained pupil dilation when viewing direct- than deviated-gaze faces over the period 3 to 7 s after stimulus onset, regardless of stimulus sex. In contrast, male observers did not show a consistent pattern in response to either the gaze or sex of the face stimuli. These findings indicate a sex difference in the processing of gaze direction and suggest that females, but not males, apply increased effort to processing socially relevant (direct-gaze) than irrelevant (deviated-gaze) faces. They also demonstrate that pupillary measurement can potentially provide new insights into the processing of even visual input, provided reflexes are sufficiently controlled.
Units of Visual Individuation in Rhesus Macaques: Objects or Unbound Features?
Authors: Cheries Erik W , Newman George E , Santos Laurie R , Scholl Brian J
Published: August 2006

Vision begins with the processing of unbound visual features, which must eventually be bound together into object representations. Such feature binding is required for coherent visual perception, and accordingly has received a considerable amount of study in several domains. Neurophysiological work, often in monkeys, has revealed the details of how and where feature binding occurs in the brain, but methodological limitations have not allowed this research to elucidate just how feature binding operates spontaneously in real-world situations. In contrast, behavioral work with human infants has demonstrated how we use simpler unbound features to individuate and identify objects over time and occlusion in many types of events, but this work has not typically been able to isolate the role of feature binding in such processing. Here we provide a method for assessing the spontaneity and fidelity of feature binding in non-human primates, as this process is utilized in real-world situations, including simple foraging behaviors. Using both looking-time and manual-search measures in a natural environment, we show that free-ranging rhesus macaques ( Macaca mulatta) spontaneously bind features in order to individuate objects across time and occlusion in dynamic events. This pattern of results demonstrates that feature binding is used in subtle ways to guide ecologically relevant behavior in a non-human animal, spontaneously and reliably, in its natural environment.
Systems analysis of PKA-mediated phosphorylation gradients in live cardiac myocytes
Authors: Saucerman Jeffrey J. , Zhang Jin , Martin Jody C. , Peng Lili X. , Stenbit Antine E. , Tsien Roger Y. , McCulloch Andrew D.
Published: August 2006

Compartmentation and dynamics of cAMP and PKA signaling are important determinants of specificity among cAMP’s myriad cellular roles. Both cardiac inotropy and the progression of heart disease are affected by spatiotemporal variations in cAMP/PKA signaling, yet the dynamic patterns of PKA-mediated phosphorylation that influence differential responses to agonists have not been characterized. We performed live-cell imaging and systems modeling of PKA-mediated phosphorylation in neonatal cardiac myocytes in response to G-protein coupled receptor stimuli and UV photolysis of “caged” cAMP. cAMP accumulation was rate-limiting in PKA-mediated phosphorylation downstream of the β-adrenergic receptor. Prostaglandin E
1
stimulated higher PKA activity in the cytosol than at the sarcolemma, whereas isoproterenol triggered faster sarcolemmal responses than cytosolic, likely due to restricted cAMP diffusion from submembrane compartments. Localized UV photolysis of caged cAMP triggered gradients of PKA-mediated phosphorylation, enhanced by phosphodiesterase activity and PKA-mediated buffering of cAMP. These findings indicate that combining live-cell FRET imaging and mechanistic computational models can provide quantitative understanding of spatiotemporal signaling.
Binaural and cochlear disparities
Authors: Joris Philip X. , Van de Sande Bram , Louage Dries H. , van der Heijden Marcel
Published: August 2006

Binaural auditory neurons exhibit “best delays” (BDs): They are maximally activated at certain acoustic delays between sounds at the two ears and thereby signal spatial sound location. BDs arise from delays internal to the auditory system, but their source is controversial. According to the classic Jeffress model, they reflect pure time delays generated by differences in axonal length between the inputs from the two ears to binaural neurons. However, a relationship has been reported between BDs and the frequency to which binaural neurons are most sensitive (the characteristic frequency), and this relationship is not predicted by the Jeffress model. An alternative hypothesis proposes that binaural neurons derive their input from slightly different places along the two cochleas, which induces BDs by virtue of the slowness of the cochlear traveling wave. To test this hypothesis, we performed a coincidence analysis on spiketrains of pairs of auditory nerve fibers originating from different cochlear locations. In effect, this analysis mimics the processing of phase-locked inputs from each ear by binaural neurons. We find that auditory nerve fibers that innervate different cochlear sites show a maximum number of coincidences when they are delayed relative to each other, and that the optimum delays decrease with characteristic frequency as in binaural neurons. These findings suggest that cochlear disparities make an important contribution to the internal delays observed in binaural neurons.
Sequestering carbon dioxide into complex structures of naturally occurring gas hydrates
Authors: Park Youngjune , Kim Do-Youn , Lee Jong-Won , Huh Dae-Gee , Park Keun-Pil , Lee Jaehyoung , Lee Huen
Published: August 2006

Large amounts of CH
4
in the form of solid hydrates are stored on continental margins and in permafrost regions. If these CH
4
hydrates could be converted into CO
2
hydrates, they would serve double duty as CH
4
sources and CO
2
storage sites. We explore here the swapping phenomenon occurring in structure I (sI) and structure II (sII) CH
4
hydrate deposits through spectroscopic analyses and its potential application to CO
2
sequestration at the preliminary phase. The present 85% CH
4
recovery rate in sI CH
4
hydrate achieved by the direct use of binary N
2
+ CO
2
guests is surprising when compared with the rate of 64% for a pure CO
2
guest attained in the previous approach. The direct use of a mixture of N
2
+ CO
2
eliminates the requirement of a CO
2
separation/purification process. In addition, the simultaneously occurring dual mechanism of CO
2
sequestration and CH
4
recovery is expected to provide the physicochemical background required for developing a promising large-scale approach with economic feasibility. In the case of sII CH
4
hydrates, we observe a spontaneous structure transition of sII to sI during the replacement and a cage-specific distribution of guest molecules. A significant change of the lattice dimension caused by structure transformation induces a relative number of small cage sites to reduce, resulting in the considerable increase of CH
4
recovery rate. The mutually interactive pattern of targeted guest–cage conjugates possesses important implications for the diverse hydrate-based inclusion phenomena as illustrated in the swapping process between CO
2
stream and complex CH
4
hydrate structure.
The peptide-catalyzed stereospecific synthesis of tetroses: A possible model for prebiotic molecular evolution
Authors: Weber Arthur L. , Pizzarello Sandra
Published: August 2006

Using a water-based prebiotic model of sugar synthesis involving glycolaldehyde self-condensation, we demonstrate that homochiral
l
-dipeptide catalysts lead to the stereospecific syntheses of tetroses. The asymmetric effect is largest for erythrose, which may reach a
d
-enantiomeric excess of >80% with
l
-Val-
l
-Val catalyst. Based on results obtained with various peptides, we propose a possible catalytic-reaction intermediate, consisting of an imidazolidinone ring formed between the two nitrogen atoms of the peptide catalyst and the C1 of one glycolaldehyde molecule. The study was motivated by the premise that exogenous material, such as the nonracemic amino acids found in meteorites, could have participated in the terrestrial evolution of molecular asymmetry by stereospecific catalysis. Because peptides might have formed readily on the early Earth, it is possible that their catalytic contribution was relevant in the prebiotic processes that preceded the onset of life.
C–H bond activation through steric crowding of normally inert ligands in the sterically crowded gadolinium and yttrium (C
5
Me
5
)
3
M complexes
Authors: Evans William J. , Davis Benjamin L. , Champagne Timothy M. , Ziller Joseph W.
Published: August 2006

Synthesis of the sterically crowded Tris(pentamethylcyclopentadienyl) lanthanide complexes, (C
5
Me
5
)
3
Ln, has demonstrated that organometallic complexes with unconventionally long metal ligand bond lengths can be isolated that provide options to develop new types of ligand reactivity based on steric crowding. Previously, the (C
5
Me
5
)
3
M complexes were known only with the larger lanthanides, La–Sm. The synthesis of even more crowded complexes of the smaller metals Gd and Y is reported here. These complexes allow an evaluation of the size/reactivity correlations previously limited to the larger metals and demonstrate a previously undescribed type of C
5
Me
5
-based reaction, namely C–H bond activation. (C
5
Me
5
)
3
Gd, was prepared from GdCl
3
through (C
5
Me
5
)
2
GdCl
2
K(THF)
2
, (C
5
Me
5
)
2
Gd(C
3
H
5
), and [(C
5
Me
5
)
2
Gd][BPh
4
] and structurally characterized by x-ray crystallography. Although Gd
3+
is redox-inactive, (C
5
Me
5
)
3
Gd functions as a reducing agent in reactions with 1,3,5,7-cyclooctatetraene (COT) and triphenylphosphine selenide to make (C
5
Me
5
)Gd(C
8
H
8
), [(C
5
Me
5
)
2
Gd]
2
Se
2
, and [(C
5
Me
5
)
2
Gd]
2
Se depending on the stoichiometry used. When the analogous synthetic method was attempted with yttrium in arene solvents, the previously characterized (C
5
Me
5
)
2
YR complexes (R=C
6
H
5
, CH
2
C
6
H
5
) were isolated instead, i.e., C–H bond activation of solvent occurred. To avoid this problem, (C
5
Me
5
)
3
Y was synthesized in high yield from [(C
5
Me
5
)
2
YH]
2
and tetramethylfulvene in aliphatic solvents. Isolated (C
5
Me
5
)
3
Y was found to metalate benzene and toluene with concomitant formation of C
5
Me
5
H, a reaction contrary to the normal pK
a
values of these hydrocarbons. In this case, the normally inert (C
5
Me
5
)
1−
ligand engages in C–H bond activation due to the extreme steric crowding.
T cell surface redox levels determine T cell reactivity and arthritis susceptibility
Authors: Gelderman Kyra A. , Hultqvist Malin , Holmberg Jens , Olofsson Peter , Holmdahl Rikard
Published: August 2006

Rats and mice with a lower capacity to produce reactive oxygen species (ROS) because of allelic polymorphisms in theNcf1gene (which encodes neutrophil cytosolic factor 1) are more susceptible to develop severe arthritis. These data suggest that ROS are involved in regulating the immune response. We now show that the lower capacity to produce ROS is associated with an increased number of reduced thiol groups (−SH) on T cell membrane surfaces. Artificially increasing the number of reduced thiols on T cells from animals with arthritis-protectiveNcf1alleles by glutathione treatment lowered the threshold for T cell reactivity and enhanced proliferative responsesin vitroandin vivo. Importantly, T cells from immunized congenic rats with an E3-derived Ncf1 allele (DA.Ncf1E3rats) that cannot transfer arthritis to rats with an arthritis-associated Dark Agouti (DA)-derived mutated Ncf1 allele (DA.Ncf1DArats) became arthritogenic after increasing cell surface thiol levels. This finding was confirmed by the reverse experiment, in which oxidized T cells from DA.Ncf1DArats induced less severe arthritis compared with controls. Therefore, we conclude that ROS production as controlled byNcf1is important in regulating surface redox levels of T cells and thereby suppresses autoreactivity and arthritis development.
Bistable expression of
WOR1
, a master regulator of white–opaque switching in
Candida albicans
Authors: Huang Guanghua , Wang Huafeng , Chou Song , Nie Xinyi , Chen Jiangye , Liu Haoping
Published: August 2006

Candida albicans
, a commensal organism and a pathogen of humans, can switch stochastically between a white phase and an opaque phase without an intermediate phase. The white and opaque phases have distinct cell shapes and gene expression programs. Once switched, each phase is stable for many cell divisions. White–opaque switching is under a1–α2 repression and therefore only happens in a or α cells. Mechanisms that control the switching are unknown. Here, we identify Wor1 (white–opaque regulator 1) as a master regulator of white–opaque switching. The deletion of
WOR1
blocks opaque cell formation. The ectopic expression of
WOR1
converts all cells to stable opaque cells in a or α cells. In addition, the ectopic expression of
WOR1
in a/α cells is sufficient to induce opaque cell formation. Importantly,
WOR1
expression displays an all-or-none pattern. It is undetectable in white cells, and it is highly expressed in opaque cells. The ectopic expression of Wor1 induces the transcription of
WOR1
from the
WOR1
locus, which correlates with the switch to opaque phase. We present genetic evidence for feedback regulation of
WOR1
transcription. The feedback regulation explains the bistable and stochastic nature of white–opaque switching.
Orientation selectivity in visual cortex by fluctuation-controlled criticality
Authors: Tao Louis , Cai David , McLaughlin David W. , Shelley Michael J. , Shapley Robert
Published: August 2006

Within a large-scale neuronal network model of macaque primary visual cortex, we examined how intrinsic dynamic fluctuations in synaptic currents modify the effect of strong recurrent excitation on orientation selectivity. Previously, we showed that, using a strong network inhibition countered by feedforward and recurrent excitation, the cortical model reproduced many observed properties of simple and complex cells. However, that network’s complex cells were poorly selective for orientation, and increasing cortical self-excitation led to network instabilities and unrealistically high firing rates. Here, we show that a sparsity of connections in the network produces large, intrinsic fluctuations in the cortico-cortical conductances that can stabilize the network and that there is a critical level of fluctuations (controllable by sparsity) that allows strong cortical gain and the emergence of orientation-selective complex cells. The resultant sparse network also shows near contrast invariance in its selectivity and, in agreement with recent experiments, has extracellular tuning properties that are similar in pinwheel center and iso-orientation regions, whereas intracellular conductances show positional dependencies. Varying the strength of synaptic fluctuations by adjusting the sparsity of network connectivity, we identified a transition between the dynamics of bistability and without bistability. In a network with strong recurrent excitation, this transition is characterized by a near hysteretic behavior and a rapid rise of network firing rates as the synaptic drive or stimulus input is increased. We discuss the connection between this transition and orientation selectivity in our model of primary visual cortex.
The housekeeping dipeptide permease is the
Escherichia coli
heme transporter and functions with two optional peptide binding proteins
Authors: Létoffé Sylvie , Delepelaire Philippe , Wandersman Cécile
Published: August 2006

Heme, a major iron source, is transported through the outer membrane of Gram-negative bacteria by specific heme/hemoprotein receptors and through the inner membrane by heme-specific, periplasmic, binding protein-dependent, ATP-binding cassette permeases.
Escherichia coli
K12 does not use exogenous heme, and no heme uptake genes have been identified. Nevertheless, a recombinant
E. coli
strain expressing just one foreign heme outer membrane receptor can use exogenous heme as an iron source. This result suggests either that heme might be able to cross the cytoplasmic membrane in the absence of specific carrier or that there is a functional inner membrane heme transporter. Here, we show that to use heme iron
E. coli
requires the dipeptide inner membrane ATP-binding cassette transporter (DppBCDF) and either of two periplasmic binding proteins: MppA, the
l
-alanyl-γ-
d
-glutamyl-meso-diaminopimelate binding protein, or DppA, the dipeptide binding protein. Thus, wild-type
E. coli
has a peptide/heme permease despite being unable to use exogenous heme. DppA, which shares sequence similarity with the
Haemophilus influenzae
heme-binding protein HbpA, and MppA are functional heme-binding proteins. Peptides compete with heme for binding both “
in vitro
” and “
in vivo
.”