bluuebunny/crossref_metadata_2025 huggingface dataset:
Presynaptic Homeostatic Plasticity Rescues Long-Term Depression after Chronic Δ9-Tetrahydrocannabinol Exposure
Authors: Mato Susana , Robbe David , Puente Nagore , Grandes Pedro , Manzoni Olivier J.
Published: December 2005

Alterations of long-term synaptic plasticity have been proposed to participate in the development of addiction. To preserve synaptic functions, homeostatic processes must be engaged after exposure to abused drugs. At the mouse cortico-accumbens synapses, a singlein vivoinjection of Δ9-tetrahydrocannabinol (THC) suppresses endocannabinoid-mediated long-term depression. Using biochemical and electrophysiological approaches, we now report that 1 week of repeatedin vivoTHC treatment reduces the coupling efficiency of cannabinoid CB1 receptors (CB1Rs) to Gi/otransduction proteins, as well as CB1R-mediated inhibition of excitatory synaptic transmission at the excitatory synapses between the prefrontal cortex and the nucleus accumbens (NAc). Nonetheless, we found that cortico-accumbens synapses unexpectedly express normal long-term depression because of a reversible switch in its underlying mechanisms. The present data show that, in THC-treated mice, long-term depression is expressed because a presynaptic mGluR2/3 (metabotropic glutamate receptor 2/3)-dependent mechanism replaces the impaired endocannabinoid system. Thus, in the NAc, a novel form of presynaptic homeostasis rescues synaptic plasticity from THC-induced deficits.
Hedonic Hot Spot in Nucleus Accumbens Shell: Where Do μ-Opioids Cause Increased Hedonic Impact of Sweetness?
Authors: Peciña Susana , Berridge Kent C.
Published: December 2005

μ-Opioid systems in the medial shell of the nucleus accumbens contribute to hedonic impact (“liking”) for sweetness, food, and drug rewards. But does the entire medial shell generate reward hedonic impact? Or is there a specific localized site for opioid enhancement of hedonic “liking” in the medial shell? And how does enhanced taste hedonic impact relate to opioid-stimulated increases in food intake? Here, we used a functional mapping procedure based on microinjection Fos plumes to localize opioid substrates in the medial shell of the nucleus accumbens that cause enhanced “liking” reactions to sweet pleasure and that stimulate food intake. We mapped changes in affective orofacial reactions of “liking”/“disliking” elicited by sucrose or quinine tastes afterd-Ala2-N-Me-Phe4-Glycol5-enkephalin (DAMGO) microinjections in rats and compared hedonic increases to food intake stimulated at the same sites. Our maps indicate that opioid-induced increases in sucrose hedonic impact are generated by a localized cubic millimeter site in a rostrodorsal region of the medial shell. In contrast, all regions of the medial shell generated DAMGO-induced robust increases in eating behavior and food intake. Thus, our results identify a locus for opioid amplification of hedonic impact and reveal a distinction between opioid mechanisms of food intake and hedonic impact. Opioid circuits for stimulating food intake are widely distributed, whereas hedonic “liking” circuits are more tightly localized in the rostromedial shell of the nucleus accumbens.
Short-Term Regulation of Information Processing at the Corticoaccumbens Synapse
Authors: Casassus Guillaume , Blanchet Christophe , Mulle Christophe
Published: December 2005

In relation to expectation and delivery of reward, pyramidal neurons of the prefrontal cortex either switch from a single spiking mode to transient phasic bursting, or gradually increase their sustained tonic activity. Here, we examined how switching between firing modes affects information processing at the corticoaccumbens synapse. We report that increasing presynaptic firing frequency in a tonic manner either depresses or facilitates synaptic transmission, depending on initial probability of release. In contrast, repeated bursts of stimulation of cortical afferents trigger a new form of short-term potentiation of synaptic transmission (RB-STP) in the nucleus accumbens (NAc). RB-STP involves the regulation of axonal excitability mediated by 4-AP-sensitive potassium channels in afferent cortical neurons. Thus, in a tonic mode, information flow is tightly controlled by regulatory mechanisms at the level of presynaptic terminals, whereas switching to a bursting mode reliably enhances efficacy of information processing for all cortical afferents to NAc neurons.
BACE1, a Major Determinant of Selective Vulnerability of the Brain to Amyloid-β Amyloidogenesis, is Essential for Cognitive, Emotional, and Synaptic Functions
Authors: Laird Fiona M. , Cai Huaibin , Savonenko Alena V. , Farah Mohamed H. , He Kaiwen , Melnikova Tatyana , Wen Hongjin , Chiang Hsueh-Cheng , Xu Guilian , Koliatsos Vassilis E. , Borchelt David R. , Price Donald L. , Lee Hey-Kyoung , Wong Philip C.
Published: December 2005

A transmembrane aspartyl protease termed β-site APP cleavage enzyme 1 (BACE1) that cleaves the amyloid-β precursor protein (APP), which is abundant in neurons, is required for the generation of amyloid-β (Aβ) peptides implicated in the pathogenesis of Alzheimer's disease (AD). We now demonstrate that BACE1, enriched in neurons of the CNS, is a major determinant that predisposes the brain to Aβ amyloidogenesis. The physiologically high levels of BACE1 activity coupled with low levels of BACE2 and α-secretase anti-amyloidogenic activities in neurons is a major contributor to the accumulation of Aβ in the CNS, whereas other organs are spared. Significantly, deletion ofBACE1inAPPswe;PS1ΔE9mice prevents both Aβ deposition and age-associated cognitive abnormalities that occur in this model of Aβ amyloidosis. Moreover, Aβ deposits are sensitive toBACE1dosage and can be efficiently cleared from the CNS whenBACE1is silenced. However,BACE1null mice manifest alterations in hippocampal synaptic plasticity as well as in performance on tests of cognition and emotion. Importantly, memory deficits but not emotional alterations inBACE1–/–mice are prevented by coexpressingAPPswe;PS1ΔE9transgenes, indicating that other potential substrates of BACE1 may affect neural circuits related to emotion. Our results establish BACE1 and APP processing pathways as critical for cognitive, emotional, and synaptic functions, and future studies should be alert to potential mechanism-based side effects that may occur with BACE1 inhibitors designed to ameliorate Aβ amyloidosis in AD.
Activity-Dependent Acceleration of Endocytosis at a Central Synapse
Authors: Wu Wei , Xu Jianhua , Wu Xin-Sheng , Wu Ling-Gang
Published: December 2005

Accumulated evidence indicates the existence of rapid and slow endocytosis at many synapses. It has been proposed that rapid endocytosis is activated by intense stimulation when vesicle recycling needs to be speeded up to supply vesicles at hippocampal synapses. However, the evidence, as obtained with imaging techniques, which are somewhat indirect in indicating rapid endocytosis, is controversial. Furthermore, a slower time course of endocytosis is often found after more intense nerve activity, casting doubt on the role of rapid endocytosis at synapses. Here, we addressed this issue at a mammalian central synapse, the calyx of Held, using a capacitance measurement technique that provides a higher time resolution than imaging techniques. We found that rapid endocytosis with a time constant of ∼1–2 s was activated during intense nerve activity. Reducing the presynaptic calcium current or buffering the intracellular calcium with EGTA significantly inhibited rapid endocytosis, suggesting that calcium triggers rapid endocytosis. During intense stimulation, rapid endocytosis retrieved up to approximately eight vesicles per second per active zone, approximately eightfold larger than reported in the hippocampus, and thus played a dominant role during and within 3 s after intense stimulation. Slow endocytosis became dominant 3 s after intense stimulation likely because of the fall of the intracellular calcium level that deactivated rapid endocytosis. These results underscore the importance of calcium-triggered rapid endocytosis, which offers the nerve terminal the plasticity to speed up vesicle cycling during intense nerve activity.
Focal and Temporal Release of Glutamate in the Mushroom Bodies Improves Olfactory Memory inApis mellifera
Authors: Locatelli Fernando , Bundrock Gesine , Müller Uli
Published: December 2005

In contrast to vertebrates, the role of the neurotransmitter glutamate in learning and memory in insects has hardly been investigated. The reason is that a pharmacological characterization of insect glutamate receptors is still missing; furthermore, it is difficult to locally restrict pharmacological interventions. In this study, we overcome these problems by using locally and temporally defined photo-uncaging of glutamate to study its role in olfactory learning and memory formation in the honeybee,Apis mellifera. Uncaging glutamate in the mushroom bodies immediately after a weak training protocol induced a higher memory rate 2 d after training, mimicking the effect of a strong training protocol. Glutamate release before training does not facilitate memory formation, suggesting that glutamate mediates processes triggered by training and required for memory formation. Uncaging glutamate in the antennal lobes shows no effect on memory formation. These results provide the first direct evidence for a temporally and locally restricted function of glutamate in memory formation in honeybees and insects.
Trial-by-Trial Coupling of Concurrent Electroencephalogram and Functional Magnetic Resonance Imaging Identifies the Dynamics of Performance Monitoring
Authors: Debener Stefan , Ullsperger Markus , Siegel Markus , Fiehler Katja , von Cramon D. Yves , Engel Andreas K.
Published: December 2005

Goal-directed behavior requires the continuous monitoring and dynamic adjustment of ongoing actions. Here, we report a direct coupling between the event-related electroencephalogram (EEG), functional magnetic resonance imaging (fMRI), and behavioral measures of performance monitoring in humans. By applying independent component analysis to EEG signals recorded simultaneously with fMRI, we found the single-trial error-related negativity of the EEG to be systematically related to behavior in the subsequent trial, thereby reflecting immediate behavioral adjustments of a cognitive performance monitoring system. Moreover, this trial-by-trial EEG measure of performance monitoring predicted the fMRI activity in the rostral cingulate zone, a brain region thought to play a key role in processing of response errors. We conclude that investigations of the dynamic coupling between EEG and fMRI provide a powerful approach for the study of higher order brain functions.
GABAAReceptor-Mediated Tonic Inhibition in Thalamic Neurons
Authors: Cope David W. , Hughes Stuart W. , Crunelli Vincenzo
Published: December 2005

Tonic GABAAreceptor-mediated inhibition is typically generated byδ subunit-containing extrasynaptic receptors. Because the δ subunit is highly expressed in the thalamus, we tested whether thalamocortical (TC) neurons of the dorsal lateral geniculate nucleus (dLGN) and ventrobasal complex exhibit tonic inhibition. Focal application of gabazine (GBZ) (50 μm) revealed the presence of a 20 pA tonic current in 75 and 63% of TC neurons from both nuclei, respectively. No tonic current was observed in GABAergic neurons of the nucleus reticularis thalami (NRT). Bath application of 1μmGABA increased tonic current amplitude to ∼70 pA in 100% of TC neurons, but it was still not observed in NRT neurons. In dLGN TC neurons, the tonic current was sensitive to low concentrations of the δ subunit-specific receptor agonists allotetrahydrodeoxycorticosterone (100 nm) and 4,5,6,7-tetrahydroisoxazolo[5,4-c]-pyridin-3-ol (THIP) (100 nm) but insensitive to the benzodiazepine flurazepam (5 μm). Bath application of low concentrations of GBZ (25–200 nm) preferentially blocked the tonic current, whereas phasic synaptic inhibition was primarily maintained. Under intracellular current-clamp conditions, the preferential block of the tonic current with GBZ led to a small depolarization and increase in input resistance. Using extracellular single-unit recordings, block of the tonic current caused the cessation of low-threshold burst firing and promoted tonic firing. Enhancement of the tonic current by THIP hyperpolarized TC neurons and promoted burst firing. Thus, tonic current in TC neurons generates an inhibitory tone. Its modulation contributes to the shift between different firing modes, promotes the transition between different behavioral states, and predisposes to absence seizures.
Few CaV1.3 Channels Regulate the Exocytosis of a Synaptic Vesicle at the Hair Cell Ribbon Synapse
Authors: Brandt Andreas , Khimich Darina , Moser Tobias
Published: December 2005

Hearing relies on faithful sound coding at hair cell ribbon synapses, which use Ca2+-triggered glutamate release to signal with submillisecond precision. Here, we investigated stimulus–secretion coupling at mammalian inner hair cell (IHC) synapses to explore the mechanisms underlying this high temporal fidelity. Using nonstationary fluctuation analysis on Ca2+tail currents, we estimate that IHCs contain ∼1700 Ca2+channels, mainly of CaV1.3 type. We show by immunohistochemistry that the CaV1.3 Ca2+channels are localized preferentially at the ribbon-type active zones of IHCs. We argue that each active zone holds ∼80 Ca2+channels, of which probably <10 open simultaneously during physiological stimulation. We then manipulated the Ca2+current by primarily changing single-channel current or open-channel number. Effects on exocytosis of the readily releasable vesicle pool (RRP) were monitored by membrane capacitance recordings. Consistent with the high intrinsic Ca2+cooperativity of exocytosis, RRP exocytosis changed nonlinearly with the Ca2+current when varying the single-channel current. In contrast, the apparent Ca2+cooperativity of RRP exocytosis was close to unity when primarily manipulating the number of open channels. Our findings suggest a Ca2+channel–release site coupling in which few nearby CaV1.3 channels impose high nanodomain [Ca2+] on release sites in IHCs during physiological stimulation. We postulate that the IHC ribbon synapse uses this Ca2+nanodomain control of exocytosis to signal with high temporal precision already at low sound intensities.
Functional Magnetic Resonance Imaging Shows Oxytocin Activates Brain Regions Associated with Mother–Pup Bonding during Suckling
Authors: Febo Marcelo , Numan Michael , Ferris Craig F.
Published: December 2005

Oxytocin is released in the maternal brain during breastfeeding and may help strengthen the mother–infant relationship. Here, we used functional magnetic resonance imaging to determine whether oxytocin modulates brain activity in postpartum day 4–8 dams receiving suckling stimulation. During imaging sessions, dams were exposed to pup suckling before and after administration of an oxytocin receptor antagonist. Another group of dams received oxytocin alone. Changes in brain activation in response to suckling closely matched that elicited by oxytocin administration. The overlapping brain areas included the olfactory system, nucleus accumbens, insular cortex, prefrontal cortex, ventral tegmental area, cortical amygdala, and several cortical and hypothalamic nuclei. Blockade of oxytocin receptors largely attenuated activation in these regions. The data suggest that oxytocin may strengthen mother–infant bond formation partly by acting through brain areas involved in regulating olfactory discrimination, emotions, and reward.
A C-Terminal Domain Directs Kv3.3 Channels to Dendrites
Authors: Deng Qingwei , Rashid Asim J. , Fernandez Fernando R. , Turner Ray W. , Maler Leonard , Dunn Robert J.
Published: December 2005

Pyramidal neurons of the electrosensory lateral line lobe (ELL) ofApteronotus leptorhynchusexpress Kv3-type voltage-gated potassium channels that give rise to high-threshold currents at the somatic and dendritic levels. Two members of the Kv3 channel family,AptKv3.1 andAptKv3.3, are coexpressed in these neurons.AptKv3.3 channels are expressed at uniformly high levels in each of four ELL segments, whereasAptKv3.1 channels appear to be expressed in a graded manner with higher levels of expression in segments that process high-frequency electrosensory signals. Immunohistochemical and recombinant channel expression studies show a differential distribution of these two channels in the dendrites of ELL pyramidal neurons.AptKv3.1 is concentrated in somas and proximal dendrites, whereasAptKv3.3 is distributed throughout the full extent of the large dendritic tree. Recombinant channel expression ofAptKv3 channels throughin vivoviral injections allowed directed retargeting ofAptKv3 subtypes over the somadendritic axis, revealing that the sequence responsible for targeting channels to distal dendrites lies within the C-terminal domain of theAptKv3.3 protein. The targeting domain includes a consensus sequence predicted to bind to a PDZ (postsynaptic density-95/Discs large/zona occludens-1)-type protein–protein interaction motif. These findings reveal that different functional roles for Kv3 potassium channels at the somatic and dendritic level of a sensory neuron are attained through specific targeting that selectively distributes Kv3.3 channels to the dendritic compartment.
Distinct Mechanisms for Neurotrophin-3-Induced Acute and Long-Term Synaptic Potentiation
Authors: Je Hyun-Soo , Zhou Jianzheng , Yang Feng , Lu Bai
Published: December 2005

Although neurotrophins elicit both acute and long-term effects, it is unclear whether the two modes of action are mediated by the same or different mechanisms. Using neuromuscular junction (NMJ) as a model system, we identified three characteristic features required for long-term, but not acute, forms of synaptic modulation by neurotrophin-3 (NT-3): endocytosis of NT-3-receptor complex, activation of the PI3 kinase substrate Akt, and new protein synthesis. Long-term effects were eliminated when NT-3 was conjugated to a bead that was too large to be endocytosed or when dominant-negative dynamin was expressed in presynaptic neurons. Presynaptic inhibition of Akt also selectively prevented NT-3-mediated long-term effects. Blockade of protein translation by the mammalian target of rapamycin inhibitor rapamycin prevented the long-term structural and functional changes at the NMJ, without affecting the acute potentiation of synaptic transmission by NT-3. These results reveal fundamental differences between acute and long-term modulation by neurotrophins.
The RIKEN Super Combined Cluster as a Grid-Enabled System (Anwendung von Grid-Technologien beim Super Combined Cluster von RIKEN)
Authors: Himeno Ryutaro , Kurokawa Motoyoshi , Yuasa Hiroaki , Shigetani Takayuki
Published: December 2005

We developed the RIKEN Super Combined Cluster (hereafter “RSCC”) System, and it started operation in March 2004. It consists of a vector parallel supercomputer, five PC clusters, and a PC cluster with MDGRAPE-2 special purpose computers. We use grid computing technology so that the user can regard the system as one system, although actually it is composed of seven different computer systems.
Modeling alkali alanates for hydrogen storage by density-functional band-structure calculations
Authors: Løvvik Ole Martin , Swang Ole , Opalka Susanne M.
Published: December 2005

The alanates (complex aluminohydrides) have relatively high gravimetric hydrogen density and are among the most promising solid-state hydrogen-storage materials. In this work, the crystal structure and electronic structure of pure and mixed-alkali alanates were calculated by ground-state density-functional band-structure calculations. The results are in excellent correspondence with available experimental data. The properties of the pure alanates were compared, and the relatively high stability of the Li3AlH6 phase was pointed out as an important difference that may explain the difficulty of hydrogenating lithium alanate. The alkali alanates are nonmetallic with calculated band gaps around 5 eV and 2.5–3 eV for the tetra- and hexahydrides. The bonding was identified as ionic between the alkali cations and the aluminohydride complexes, while it is polar covalent within the complex. A broad range of hypothetical mixed-alkali alanate compounds was simulated, and four were found to be stable compared to the pure alanates and each other: LiNa2AlH6, K2LiAlH6, K2NaAlH6, and K2.5Na0.5AlH6. No mixed-alkali tetrahydrides were found to be stable, and this was explained by the local coordination within the different compounds. The only alkali alanate that seemed to be close to fulfilling the international hydrogen density targets was NaAlH4.
Tailoring singlewalled carbon nanotubes for hydrogen storage
Authors: Haas M.K. , Zielinski J.M. , Dantsin G. , Coe C.G. , Pez G.P. , Cooper A.C.
Published: December 2005

Hydrogen isotherms on a variety of single-walled carbon nanotube (SWNT) samples were measured using a differential pressure adsorption apparatus, which provides highly accurate data. A number of these SWNT samples were modified by a non-destructive cutting process, which reduced the aspect ratio of the nanotube bundles by two orders of magnitude. There were no apparent differences in the microporosity of SWNT as a function of aspect ratio. The adsorption of helium on SWNT is shown to be non-negligible and results in artificially low hydrogen capacities using conventional adsorption methodology. With no accounting for helium adsorption, the hydrogen adsorption results show that cut and uncut SWNT have similar hydrogen capacities of <1 wt% at 25 °C and pressures up to 110 bar. However, an analysis of hydrogen capacity versus N2Brunauer–Emmett–Teller surface area suggests that there is an enhanced heat of adsorption of hydrogen for SWNT versus activated carbon.
Flexible, conjugated polymer-fullerene-based bulk-heterojunction solar cells: Basics, encapsulation, and integration
Authors: Dennler G. , Lungenschmied C. , Neugebauer H. , Sariciftci N.S. , Labouret A.
Published: December 2005

Organic solar cells based on conjugated polymer:fullerene blends show nowadays efficiencies above 4%. After briefly presenting the science of bulk-heterojunction solar cells, we report herein a shelf lifetime study performed by encapsulating the cells in a flexible and transparent gas barrier material. This method allows lifetimes as reported for glass encapsulation. Moreover, we propose a new approach to pattern organic solar cells and design large-scale modules. This technique, based on selective Nd:yttrium aluminum garnet (YAG) laser etching, potentially enables low-cost, high-speed roll-to-roll operation.
Effect of magnetite particle size on adsorption and desorption of arsenite and arsenate
Authors: Yean S. , Cong L. , Yavuz C.T. , Mayo J.T. , Yu W.W. , Kan A.T. , Colvin V.L. , Tomson M.B.
Published: December 2005

Numerous studies have examined arsenic adsorption on varying adsorbents including iron oxides, aluminum hydroxides, alumina, and carbon as a means of arsenic removal in drinking water treatments. The objectives of this study were to evaluate the effect of magnetite particle size on the adsorption and desorption behavior of arsenite and arsenate, and to investigate the competitive adsorption between natural organic matter (NOM) and arsenic. Increases in adsorption maximum capacities for arsenite and arsenate were observed with decreasing magnetite particle size. Arsenic desorption is hysteretic, more so with the smaller nanoparticles. Such desorption hysteresis might result from a higher arsenic affinity for magnetite nanoparticles. In the presence of NOM, substantial decrease in arsenic sorption to magnetite nanoparticles was observed. It would be beneficial to thoroughly investigate adsorption and desorption of arsenic on magnetite nanoparticles for further practical purposes.
Fourier transform infrared analysis of hydroxyl content of hydrothermally processed heteroepitaxial barium titanate films
Authors: Patil Sandeep K. , Shah Nipun , Blum Frank D. , Rahaman Mohamed N.
Published: December 2005

The concentration of hydroxyl (–OH) groups in epitaxial barium titanate (BaTiO3) films (thickness ∼ 200 nm), deposited on single-crystal strontium titanate (SrTiO3) at 150 °C by a hydrothermal technique, was investigated using x-ray photoelectron spectroscopy and Fourier transform infrared (FTIR) spectroscopy. After hydrothermal treatment, a broad FTIR resonance for the hydroxyl groups indicated a significant concentration of surface –OH groups in the films. The as-deposited films were subsequently treated hydrothermally with D2O, and the kinetics of the exchange reaction between –OH incorporated into the film and –OD from the D2O were studied using FTIR. For reactions carried out intermittently, the kinetics of the exchange reaction between –OH by –OD depended not only on the total reaction time, but also on the duration of each treatment. The broad FTIR hydroxyl resonance in the as-deposited hydrothermal film was significantly reduced only after heating for 1 h at 600–800 °C.
Structure and spectroscopic properties of (AA′)(BB′)O3mixed-perovskite crystals
Authors: Pawlak Dorota A. , Ito Masahiko , Dobrzycki Lukasz , Wozniak Krzysztof , Oku Masaoki , Shimamura Kiyoshi , Fukuda Tsuguo
Published: December 2005

Five different mixed-perovskite (AA′)(BB′)O3single crystals were grown, where A = La, Nd; A′ = Sr; B = Al, Ga; and B′ = Ta, Nb. The as-grown crystals were yellowish/brownish. After annealing in air, the coloration was more intense. Annealing in a reducing atmosphere decreased coloration. The crystals were investigated by transmission spectroscopy, electron spectroscopy for chemical analysis (ESCA), and single-crystal x-ray diffraction. Additional broad absorption bands in the transmission spectra were observed for the as-grown samples. They are in line with the changes of the shape of O(1s) ESCA peaks. Redundant interstitial oxygen ions were recognized as the reason for the crystal coloration. All structures were solved and refined in different space groups of the regular system. Some of the unit cells have a doubled lattice constant: (i) lanthanum strontium gallium niobate,Pm3m,3.9323(5) Å, at 100 K, 3.9270(5) Å; (ii) neodymium strontium aluminum tantalate,Pm3m,3.8353(4) Å; (iii) lanthanum strontium aluminum tantalate,Pn3m,7.720(1) Å, annealed in reducing atmosphere, 7.708(1) Å; (iv) neodymium strontium aluminum niobate,Fm3m,7.744(4) Å.
Defect-induced vibrational response of multi-walled carbon nanotubes using resonance Raman spectroscopy
Authors: Curran S.A. , Talla J.A. , Zhang D. , Carroll D.L.
Published: December 2005

We systematically introduced defects onto the body of multi-walled carbon nanotubes through an acid treatment, and the evolution of these defects was examined by Raman spectroscopy using different excitation wavelengths. The D and D′ modes are most prominent and responsive to defect formation caused by acid treatment and exhibit dispersive behavior upon changing the excitation wavelengths as expected from the double resonance Raman (DRR) mechanism. Several weaker Raman resonances including D″ and L1 (L2) + D′ modes were also observed at the lower excitation wavelengths (633 and 785 nm). In addition, specific structural defects including the typical pentagon-heptagon structure (Stone–Wales defects) were identified by Raman spectroscopy. In a closer analysis we also observed Haeckelite structures, specifically Ag mode response in R5,7 and O5,6,7.
Utility of dodecyl sulfate surfactants as dissolution inhibitors in chemical mechanical planarization of copper
Authors: Hong Y. , Patri U.B. , Ramakrishnan S. , Roy D. , Babu S.V.
Published: December 2005

An important component of the slurries used in chemical mechanical planarization (CMP) is an appropriately chosen corrosion/dissolution inhibitor, which facilitates selective material removal from protrusions while protecting recessed regions of the surface. The present work demonstrates the utility of two environmentally benign anionic surfactants, sodium dodecyl sulfate (SDS) and ammonium dodecyl sulfate (ADS) as dissolution inhibitors. Using a standard slurry (1 wt% glycine with 5 wt% H2O2 at pH = 4.0) typically used for Cu CMP and combining measurements of open circuit potentials and contact angles with those of Cu removal rates, we show that both SDS and ADS suppress chemical dissolution and polish rates of Cu. The dissolution inhibition efficiencies of ADS and SDS measured in these experiments are found to be superior to those of benzotriazole (BTA), a traditional inhibiting agent used for copper CMP.
Electromigration-induced Pb segregation in eutectic Sn–Pb molten solder
Authors: Liao Chien-Neng , Chung Chien-Ping , Chen Wen-Tai
Published: December 2005

Preferential Pb electromigration (EM) in eutectic Sn–Pb molten solder was characterized by examining Pb segregation at the anode of the solder on a thin stripe of Cu metallization. The eutectic Sn–Pb molten solder stressed at current densities of 103−104 A/cm2 was found to form columnar Pb-rich phase (α) at the anode side and Pb deficiency at the cathode side. The columnar α-phase grew in the direction parallel to the electron flow, and its growth rate increased proportionally with the current density applied through the molten solder. By measuring the growth rate of the columnar α-phase, we calculated the Pb effective charge number of EM in the eutectic Sn–Pb molten solder to be 2.7, which is one order of magnitude lower than the reported value of 47 for self-electromigration in bulk Pb. The mechanism for the EM-induced Pb segregation in Sn–Pb solder was also explored.
Compliant thin film patterns of stiff materials as platforms for stretchable electronics
Authors: Li Teng , Suo Zhigang , Lacour Stéphanie P. , Wagner Sigurd
Published: December 2005

A thin film of a stiff material, patterned as a serpentine on a flat elastomeric substrate, can elongate substantially when the substrate is pulled. We showed that the film elongates by twisting out of plane, accommodated by the compliance of the substrate and the pattern of the film. Consequently, large elongations of the substrate induce small strains in the film, even when the width of the film is much larger than its thickness. Such a wide serpentine, or other compliant patterns of stiff materials, can serve as a platform on which electronic circuits can be fabricated. This architecture will make electronics elastically stretchable.
Digestibility of Gross Nutrients by Sunshine Bass in Animal By-Products and Commercially Blended Products Used as Fish Meal Replacements
Authors: Rawles Steven D , Gaylord T Gibson , Gatlin Delbert M.
Published: December 2005

To more accurately formulate feeds for hybrid striped bass (white bass Morone chrysops × striped bass M. saxatilis), data on the availability of nutrients from feedstuffs are needed to complement information on nutritional requirements. An experiment was conducted to determine the apparent digestibility coefficients (ADCs) of protein, lipid, energy, and organic matter for an assortment of commercially available feedstuffs and blended products used as fish meal replacements. The feedstuffs tested were ring-dried blood meal, poultry by-product meal, fish solubles, and four commercially blended fish meal substitutes (PRO-PAK, PRO-PAK 65, Pro-Con 65RDB, and 60FMC). Organic matter ADCs for these products ranged from 47% for 60FMC to 130% for fish solubles, while energy ADCs paralleled these values and ranged from 48% (60FMC) to 114% (fish solubles). Lipid ADCs ranged from 49% for PRO-PAK 65 to 79% for poultry by-product meal, and protein ADCs ranged from 47% for 60FMC to 70% for fish solubles. These values provide needed information to feed manufacturers and will allow for more accurate substitutions for these feedstuffs in aquafeeds.
Reducing Length Variation in Juvenile Steelhead and Coho Salmon through the Use of the AutoFish Tagging Trailer System
Authors: Tipping Jack M , Seidel Paul R
Published: December 2005

The coefficient of variation (CV) in length of steelhead Oncorhynchus mykiss and coho salmon O. kisutch sorted with the AutoFish tagging trailer (AFTT) system (Northwest Marine Technology, Shaw Island, Washington) was compared with that of unsorted fish. At release in April, the mean CV of sorted steelhead was 22% less than that of control fish, and the two values were significantly different. Since fish are only handled once with the AFTT, there are also labor savings relative to traditional hatchery practices in which fish are sorted and later fin-clipped. In coho salmon, the mean CV of sorted fish was only 7% less than that of control fish (no significant difference), suggesting that there are few added advantages in using the AFTT for coho salmon.
Detailed molecular simulations to investigate multicomponent diffusion models
Authors: Patel Harshit A. , Garde Shekhar , Nauman E. Bruce
Published: December 2005

The theoretical treatment of multicomponent diffusion is complicated by the generally unknown dependence of diffusivities on the local concentration of species. As pointed out by Nauman and Savoca in 2001, the standard treatment uses an n‐1 by n‐1 matrix of diffusion coefficients for an n‐component system and can give anomalous and non‐physical results when there is no dominant component and when the various components have significantly different diffusivities. Although theoretically resolved by postulating diffusivities with suitable concentration dependence, there has been no practical resolution of this problem short of unrealistic, exhaustive experimentation. Nauman and Savoca proposed two models for multicomponent diffusion that produce only physically possible results, but they were unable to suggest which model was better. This article reports on molecular dynamic experiments that were designed to differentiate between the models. Specifically studied were ternary, liquid mixtures of ethane, octane, and hexadecane. It was found that the proportional flux model agrees with the molecular simulations. No cross‐diffusion was observed in agreement with this model and in contrast to the alternative, pair‐wise flux model. The proportional flux model is easy to implement and requires a minimum of data, although detailed, compositional dependent diffusion coefficients can be incorporated into the model when such data are available. © 2005 American Institute of Chemical Engineers AIChE J, 2006
Distribution of postpartum amenorrhea in rural Bangladeshi women
Authors: Holman Darryl J. , Grimes Michael A. , Achterberg Jerusha T. , Brindle Eleanor , O'Connor Kathleen A.
Published: December 2005

Previous studies of postpartum amenorrhea (PPA) demonstrated distinct subgroups of women with short and long durations of amenorrhea. This phenomenon was attributed to cases where breastfeeding is absent because of pregnancy loss or infant death, or confusion of postpartum bleeding with resumption of menses. We explored these ideas using data from an 11‐month prospective study in Bangladesh in which 858 women provided twice‐weekly interviews and urine specimens for up to 9 months; 300 women were observed while experiencing PPA. The resulting exact, interval‐censored, or right‐censored durations were used to estimate parameters of two‐component mixture models. A mixture of two Weibull distributions provided the best fit to the observations. The long‐duration subgroup made up 84% (±4% SE) of the population, with a mean duration of 457 (±31) days. The short‐duration subgroup had a mean duration of 94 (±17) days. Three covariates were associated with the duration of PPA: women whose husbands had high‐wage employment had a greater probability of falling in the short‐duration subgroup; women in the long‐duration subgroup whose husbands seasonally migrated had shorter periods of PPA within the subgroup; and mothers in the short‐duration subgroup who gave birth during the monsoon season experienced a shortened duration of PPA within the subgroup. We conclude that the bimodal distribution of PPA reflects biological or behavioral heterogeneity rather than shortcomings of data collection. Am J Phys Anthropol, 2006. © 2005 Wiley‐Liss, Inc.
Life in the slow lane revisited: Ontogenetic separation between Chimpanzees and humans
Authors: Walker Robert , Hill Kim , Burger Oskar , Hurtado A. Magdalena
Published: December 2005

This study investigates the evolution of human growth by analyzing differences in body mass growth trajectories among three populations: the Ache of eastern Paraguay, the US (NHANES, 1999–2000), and captive chimpanzees. The relative growth statistic “A” from the mammalian growth law is allowed to vary with age and proves useful for comparing growth across different ages, populations, and species. We demonstrate ontogenetic separation between chimpanzees and humans, and show that interspecific differences are robust to variable environmental conditions. The human pattern of slow growth during the lengthened period from weaning to the beginning of the adolescent growth spurt is found among the Ache (low energy availability and high disease load) and also in the US (high energy availability and low disease load). The human growth pattern contrasts with that of the chimpanzee, where absolute growth rates and relative “A” values are faster and less prolonged. We suggest that selection has acted to decrease human growth rates to allow more time for increased cognitive development with lower body‐maintenance costs. Am J Phys Anthropol, 2006. © 2005 Wiley‐Liss, Inc.
Morphometric cranial identity of prehistoric Malawians in the light of sub‐Saharan African diversity
Authors: Morris Alan G. , Ribot Isabelle
Published: December 2005

Little has been described of the Holocene populations of South‐Central Africa, despite the region demonstrating major subsistence shifts relating to dispersals of agriculturalists at least 2,000 years ago. Seven sites with associated human skeletal remains were selected. Hora, Chencherere, Fingura, and Mtuzi represent the Middle Holocene (2,000–5,000 years ago), and Phwadze, Mtemankhokwe, and Nkudzi Bay represent the Late Holocene and the arrival of agriculturalists between 500–2,000 years ago. Focusing on the identity of Hora and Chencherere specimens, two questions were addressed: are the various Holocene Malawians similar to each other, or do they suggest morphological change over time? What modern populations are closest to the prehistoric specimens? The archaeological sample was compared to modern sub‐Saharan Africans from four regions, plus a historic Khoi‐San foraging group. Factor analyses were performed in order to identify complex patterns of variation in metric traits of the skull. According to the results, prehistoric Malawians showed only slight differences between the Late and Middle Holocene, suggesting a population change without any major discontinuity. Later Stone Age skulls did not exclusively show similarities with the Khoi‐San, as they frequently fit well within the variation of modern Bantu‐speaking groups, especially West‐Central Africa. Therefore, we reject the hypothesis that Middle Holocene South‐Central Africans have an exclusively Khoi‐San ancestry, and support an alternative hypothesis that both Middle and Late Holocene groups share a common biological heritage originating in West‐Central Africa in earlier times. Am J Phys Anthropol, 2006. © 2005 Wiley‐Liss, Inc.
Effect of ethnicity and sex on the growth of the axial and appendicular skeleton of children living in a developing country
Authors: Nyati Lukhanyo H. , Norris Shane A. , Cameron Noel , Pettifor John M.
Published: December 2005

Bones in the axial and appendicular skeletons exhibit heterogeneous growth patterns between different ethnic and sex groups. However, the influence of this differential growth on the expression of bone mineral content is not yet established. The aims of the present study were to investigate: 1) whether there are ethnic and sex differences in axial and appendicular dimensions of South African children; and 2) whether regional segment length is a better predictor of bone mass than stature. Anthropometric measurements of stature, weight, sitting height, and limb lengths were taken on 368 black and white, male and female 9‐year‐old children. DXA (dual‐energy x‐ray absorptiometry) scans of the distal ulna, distal radius, and hip and lumbar spine were also obtained. Analyses of covariance were performed to assess differences in limb lengths, adjusted for differences in stature. Multiple regression analyses were used to assess significant predictors of site‐specific bone mass. Stature‐adjusted means of limb lengths show that black boys have longer legs and humeri but shorter trunks than white boys. In addition, black children have longer forearms than white children, and girls have longer thighs than boys. The regression analysis demonstrated that site‐specific bone mass was more strongly associated with regional segment length than stature, but this had little effect on the overall pattern of ethnic and sex differences. In conclusion, there is a differential effect of ethnicity and sex on the growth of the axial and appendicular skeletons, and regional segment length is a better predictor of site‐specific bone mass than stature. Am J Phys Anthropol, 2006. © 2005 Wiley‐Liss, Inc.
Cranial ontogeny of Papio baboons (Papio hamadryas)
Authors: Leigh Steven R.
Published: December 2005

Cranial form in subspecies of Papio baboons (Papio hamadryas) varies in relation to size, geography, and sex. However, knowledge about this variation is based mainly on adults, precluding direct assessments of the evolutionary factors that are ultimately responsible for adult shape variation. Consequently, this study tests hypotheses about the development of size and shape differences among subspecies of Papio baboons, anticipating limited evolutionary divergences in the ontogenetic pathways leading to adult endpoints. Geometric morphometric and bivariate allometric analyses are used to explore developmental size and shape variation. Allometric scaling in adult Papio baboons occurs because both sexes and all subspecies follow similar developmental pathways to a variety of adult forms. However, complex allometry contributes to form differences, producing potentially important shape differences that emerge during development. Modest shape differences that are statistically independent of size distinguish chacma baboons (P. h. ursinus) from other forms. A small‐headed subspecies, the Kinda baboon (P. h. kindae), also presents a distinctive ontogeny, and may provide insights into the evolution of size change in this species. Variation among subspecies that is statistically independent of size involves the rostrum, zygomatic breadths, and cranial flexion. These features may be related to diet, but the precise biomechanical correlates of baboon form variation remain unclear. Am J Phys Anthropol, 2006. © 2005 Wiley‐Liss, Inc.
Phylogenetic analyses of dimorphism in primates: Evidence for stronger selection on canine size than on body size
Authors: Thorén Sandra , Lindenfors Patrik , Kappeler Peter M.
Published: December 2005

Phylogenetic comparative methods were used to analyze the consequences of sexual selection on canine size and canine size dimorphism in primates. Our analyses of previously published body mass and canine size data revealed that the degree of sexual selection is correlated with canine size dimorphism, as well as with canine size in both sexes, in haplorhine but not in strepsirrhine primates. Consistent with these results, male and female canine size was found to be highly correlated in all primates. Since canine dimorphism and canine size in both sexes in haplorhines were found to be not only related to mating system but also to body size and body size dimorphism (characters which are also subject to or the result of sexual selection), it was not apparent whether the degree of canine dimorphism is the result of sexual selection on canine size itself, or whether canine dimorphism is instead a consequence of selection on body size, or vice versa. To distinguish among these possibilities, we conducted matched‐pairs analyses on canine size after correcting for the effects of body size. These tests revealed significant effects of sexual selection on relative canine size, indicating that canine size is more important in haplorhine male‐male competition than body size. Further analyses showed, however, that it was not possible to detect any evolutionary lag between canine size and body size, or between canine size dimorphism and body size dimorphism. Additional support for the notion of special selection on canine size consisted of allometric relationships in haplorhines between canine size and canine size dimorphism in males, as well as between canine size dimorphism and body size dimorphism. In conclusion, these analyses revealed that the effects of sexual selection on canine size are stronger than those on body size, perhaps indicating that canines are more important than body size in haplorhine male‐male competition. Am J Phys Anthropol, 2006. © 2005 Wiley‐Liss, Inc.
Synthesis and photophysical properties of novel amphiphilic ruthenium (II) complexes containing 4,4′‐dialkylaminomethyl‐2,2′‐bipyridyl ligands
Authors: Kirilov Plamen , Matondo Hubert , Vicendo Patricia , Garrigues Jean‐Christophe , Baboulène Michel , Nguyen Hoang‐Phuong , Rico‐Lattes Isabelle
Published: December 2005

The synthesis of a number of new 2,2′‐bipyridine ligands functionalized with bulky amino side groups is reported. Three homoleptic polypyridyl ruthenium (II) complexes, [Ru(L)3]2+ 2(PF6−), where L is 4,4′‐dioctylaminomethyl‐2,2′‐bipyridine (Ru4a), 4,4′‐didodecylaminomethyl‐2,2′‐bipyridine (Ru4b) and 4,4′‐dioctadodecylaminomethyl‐2,2′‐bipyridine (Ru4c), have been synthesized. These compounds were characterized and their photophysical properties examined. The electronic spectra of three complexes show pyridyl π → π* transitions in the UV region and metal‐to‐ligand charge transfer bands in the visible region. Copyright © 2005 John Wiley & Sons, Ltd.
Ethylene and propylene polymerization by the new substituted bridged (cyclopentadienyl)(fluorenyl) zirconocenes
Authors: Yang Xiaoxia , Zhang Yong , Huang Jiling
Published: December 2005

Eight Cs‐symmetric complexes, R1R2C(Cp)(Flu)MCl2 [R1 = R2 = CH3CH2CH2, M = Zr (1), Hf (2); R1 = R2 = pCH3OC6H4, M = Zr (3), Hf (4); R1 = ptBuC6H4, R2 = Ph, M = Zr (5), Hf (6); R1 = R2 = ptBuC6H4, M = Zr (7); R1 = R2 = PhCH2, M = Zr (8)] have been synthesized and characterized. Zirconocenes all showed the same high catalytic activities in ethylene polymerization as complex Ph2C(Cp)(Flu)ZrCl2 (9). However, in the propylene polymerization, the catalytic activities decreased in the order 5 ≈ 9 > 7 > 8. Introduction of tBu decreased the activities, probably due to the bulk steric hindrance. The polypropylene produced by 5 and 7 with tBu substituent showed a higher molecular weight (Mη) than that produced by 9. The 13C NMR spectrum revealed the polymers from 7 and 8 to have shorter average syndiotactic block length than polymer produced by 9. It was noted that [mm] stereodefect of polypropylene by 8 could not be observed from 13C NMR, which showed that the benzyl on bridge carbon 8 prevented chain epimerization and enatiofacial misinsertion in polymerization. Copyright © 2005 John Wiley & Sons, Ltd.