bluuebunny/crossref_metadata_2025 huggingface dataset:
Cortical Pain Responses in Human Infants
Authors: Slater Rebeccah , Cantarella Anne , Gallella Shiromi , Worley Alan , Boyd Stewart , Meek Judith , Fitzgerald Maria
Published: April 2006

Despite the recent increase in our understanding of the development of pain processing, it is still not known whether premature infants are capable of processing pain at a cortical level. In this study, changes in cerebral oxygenation over the somatosensory cortex were measured in response to noxious stimulation using real-time near-infrared spectroscopy in 18 infants aged between 25 and 45 weeks postmenstrual age. The noxious stimuli were heel lances performed for routine blood sampling; no blood tests were performed solely for the purpose of the study. Noxious stimulation produced a clear cortical response, measured as an increase in total hemoglobin concentration [HbT] in the contralateral somatosensory cortex, from 25 weeks (mean Δ[HbT] = 7.74 μmol/L; SE, 1.10). Cortical responses were significantly greater in awake compared with sleeping infants, with a mean difference of 6.63 μmol/L [95% confidence interval (CI) limits: 2.35, 10.91 μmol/L; mean age, 35.2 weeks]. In awake infants, the response in the contralateral somatosensory cortex increased with age (regression coefficient, 0.698 μmol/L/week; 95% CI limits: 0.132, 1.265 μmol/L/week) and the latency decreased with age (regression coefficient, −0.9861 μmol/L/week; 95% CI limits: −1.5361, −0.4361 μmol/L/week; age range, 25–38 weeks). The response was modality specific because no response was detected after non-noxious stimulation of the heel, even when accompanied by reflex withdrawal of the foot. We conclude that noxious information is transmitted to the preterm infant cortex from 25 weeks, highlighting the potential for both higher-level pain processing and pain-induced plasticity in the human brain from a very early age.
The Dynamics of Spatiotemporal Response Integration in the Somatosensory Cortex of the Vibrissa System
Authors: Boloori Ali-Reza , Stanley Garrett B.
Published: April 2006

Spatiotemporal response integration across the neural receptive field (RF) is a general feature of sensory coding and has an important role in shaping responses to naturalistic stimuli. In the primary somatosensory cortex of the rat vibrissa pathway, such integration across the vibrissa array strongly shapes the coding of spatiotemporally distributed deflections. Using a spatiotemporal paired-pulse paradigm, this study revealed that fundamentally different types of pairwise interactions have similar qualitative behavior but that the magnitude, latency, and precision of the neural responses depend on the specific RF components being engaged. In all cases, however, increase in the suppression of response magnitude accompanied a lengthening of latency and a decrease in response precision. Furthermore, nonlinear interactions evoked by stimulation of multiple RF subregions strongly influence both response magnitude and timing to more complex sequences. Despite their complexity, such response interactions are highly predictable from elementary pairwise interactions. To understand the functional role of spatiotemporal interactions in coding, we developed a response model that incorporated the experimentally measured modulations in response magnitude, latency, and precision induced by cross-vibrissa interactions. Simulations of a simplified textural discrimination task indicate that spatiotemporal interactions enhance discrimination under certain stimulus time scales. This improvement follows from a nonlinear response property that acts to restore the neural response in the face of suppression. Together, the present findings highlight the role of response integration in shaping single-cell responses and provide predictions about how changes in response parameters influence coding accuracy.
NG2 Glial Cells Provide a Favorable Substrate for Growing Axons
Authors: Yang Zhongshu , Suzuki Ryusuke , Daniels Stephen B. , Brunquell Christopher B. , Sala Christopher J. , Nishiyama Akiko
Published: April 2006

NG2 cells (polydendrocytes) comprise an abundant glial population that is widely and uniformly distributed throughout the developing and mature CNS and are identified by the expression of the NG2 proteoglycan at the cell surface. Although recent electrophysiological studies suggest that they are capable of receiving signals from axon terminals, other studies, based on the finding that the NG2 molecule itself induces growth cone collapse, have led to a widely held speculation that NG2 cells themselves also repel and inhibit growing axons. In this study, we have examined the effects of rat NG2 cells on growing hippocampal and neocortical axonsin vitroandin vivo. NG2 cells did not repel growing axons but promoted their growthin vitro, and axonal growth cones formed extensive contacts with NG2 cells bothin vitroand in the developing corpus callosum. Punctate immunoreactivity for fibronectin and laminin was found to be colocalized with NG2 on the surface of NG2 cells. Altering the level of cell surface NG2 expression had no effect on the growth-promoting effects of NG2 cells on growing axons. Thus, our study indicates that NG2 cells are not inhibitory to growing axons but provide an adhesive substrate for axonal growth cones and promote their growth even in the presence of elevated levels of the NG2 proteoglycan. These findings suggest a novel role for NG2 cells in facilitating axonal growth during development and regeneration.
Cortical Inputs and GABA Interneurons Imbalance Projection Neurons in the Striatum of Parkinsonian Rats
Authors: Mallet Nicolas , Ballion Bérangère , Le Moine Catherine , Gonon François
Published: April 2006

The striatum receives massive cortical excitatory inputs and is densely innervated by dopamine. Striatal projection neurons form either the direct or indirect pathways. Models of Parkinson's disease propose that dopaminergic degeneration imbalances both pathways, although direct electrophysiological evidence is lacking. Here, striatal neurons were identified by electrophysiological criteria and Neurobiotin labeling combined with either immunohistochemistry orin situhybridization. Their spontaneous discharge activity and spike response to cortical stimulation were recordedin vivoin anesthetized rats rendered hemi-parkinsonian by 6-hydroxydopamine. We showed that striatonigral neurons (direct pathway) were inhibited whereas striatopallidal neurons (indirect pathway) were activated by dopaminergic lesion. We also identified, with antidromic stimulations, corticostriatal neurons that preferentially innervate striatonigral or striatopallidal neurons and showed that dopaminergic depletion selectively decreased the spontaneous activity of the former. Therefore, dopamine degeneration induces a cascade of imbalances that spread out of the basal ganglia and affect the whole basal ganglia-thalamo-cortical circuits.

Fast-spiking GABA interneurons provide potent feedforward inhibition of striatal projection neurons. We showed here that these interneurons narrowed the time window of the responses of projection neurons to cortical stimulation. In the dopamine-depleted striatum, because the intrinsic activity of these interneurons was not altered, their feedforward inhibition worsened the striatal imbalance. Indeed, the time window of the evoked responses was narrower for striatonigral neurons and wider for striatopallidal neurons. Therefore, after dopaminergic depletion, cortical inputs and GABA interneurons might imbalance striatal projection neurons and represent two novel nondopaminergic mechanisms that might secondarily contribute to the pathophysiology of Parkinson's disease.
Somatosensory Cells in Area PEc of Macaque Posterior Parietal Cortex
Authors: Breveglieri Rossella , Galletti Claudio , Gamberini Michela , Passarelli Lauretta , Fattori Patrizia
Published: April 2006

PEc is an area defined on cytoarchitectural grounds, located in the posterior part of the superior parietal lobule of macaque brain (Pandya and Seltzer, 1982). The aim of this work was to assess whether passive somatosensory stimulation elicited responses in PEc neurons. Extracellular recordings were performed in three awakeMacaca fascicularis. Passive somatosensory stimulation was performed in darkness, and eye movements were monitored continuously. Recording sites were assigned to different areas according to the cytoarchitectonic criteria described by Pandya and Seltzer (1982) and Luppino et al. (2005). Only recording sites within the limits of the cytoarchitecturally defined area PEc were taken into account in this work.

Of 147 PEc cells, 83 (56%) were modulated by passive somatosensory stimulation. The majority of them (73%) responded to joint rotations, and 24% responded to tactile skin stimulation. The majority of PEc somatosensory responses (90%) were evoked by contralateral stimulation. Joint-modulated cells were mostly activated by the upper limbs (82%). The majority of tactile receptive fields (61%) were located on the arms, and a minority was located on the legs and trunk. One-half of PEc somatosensory cells were polysensory, because they were sensitive to visual stimulation. The majority of PEc somatosensory cells were activated by active reaching movements. Somatosensory cells, somatosensory submodalities, and body part representations were not clustered in PEc subregions; in other words, PEc does not show a somatotopic organization. Although the caudal sector of the superior parietal lobule has been traditionally considered as a somatosensory area, this is the first demonstration of the presence of somatosensory cells in this cortical region.
Somatic Sensation of Hand-Object Interactive Movement Is Associated with Activity in the Left Inferior Parietal Cortex
Authors: Naito Eiichi , Ehrsson H. Henrik
Published: April 2006

Manipulation of objects and tool-use are known to be controlled by a network of frontal motor and parietal areas. Here, we investigate which of these areas are associated with the somatic sensation of hand-object interactive movement using functional magnetic resonance imaging.

To dissociate the sensation of movement from the motor control commands, we used a new kinesthetic illusion. Twelve blindfolded right-handed participants placed the palm of their right or left hand on an object (a ball). Simultaneously, we vibrated the tendon of the wrist extensor muscle. This elicited the illusion that the wrist is flexing and the touched object is also moving along with the hand (hand-object illusion). As controls, we vibrated the skin surface over the nearby bone, which does not elicit any illusions, or we vibrated the tendon when the hand did not touch the object, which only generates the illusory flexion of the hand.

We found that the hand-object illusion specifically activated the left inferior parietal lobule (IPL) (supramarginal gyrus and parietal operculum, including cytoarchitectonic areas ip1 and op1) and area 44. The left IPL was activated both during the hand-object illusions with the right and left hands, and the activity was greater than in the right corresponding parietal region, suggesting a dominant role of the left hemisphere.

We conclude that the left IPL is involved in the somatic perception of hand-object interactive movement and suggest that the underlying mechanism is the somatic integration of internal information about the body and external information about the object.
Higher-Dimensional Neurons Explain the Tuning and Dynamics of Working Memory Cells
Authors: Singh Ray , Eliasmith Chris
Published: April 2006

Measurements of neural activity in working memory during a somatosensory discrimination task show that the content of working memory is not only stimulus dependent but also strongly time varying. We present a biologically plausible neural model that reproduces the wide variety of characteristic responses observed in those experiments. Central to our model is a heterogeneous ensemble of two-dimensional neurons that are hypothesized to simultaneously encode two distinct stimuli dimensions. We demonstrate that the spiking activity of each neuron in the population can be understood as the result of a two-dimensional state space trajectory projected onto the tuning curve of the neuron. The wide variety of observed responses is thus a natural consequence of a population of neurons with a diverse set of preferred stimulus vectors and response functions in this two-dimensional space. In addition, we propose a taxonomy of network topologies that will generate the two-dimensional trajectory necessary to exploit this population. We conclude by proposing some experimental indicators to help distinguish among these possibilities.
Behavioral and Anatomical Interactions between Dopamine and Corticotropin-Releasing Factor in the Rat
Authors: Meloni Edward G. , Gerety Lyle P. , Knoll Allison T. , Cohen Bruce M. , Carlezon William A.
Published: April 2006

The neuropeptide corticotropin-releasing factor (CRF) is believed to play a role in a number of psychiatric conditions, including anxiety disorders and depression. In the present study, male Sprague Dawley rats were used to examine the behavioral effects of altering dopamine transmission on CRF-enhanced startle, a behavioral assay believed to reflect stress- or anxiety-like states. Systemic administration of the selective dopamine D1receptor antagonist SCH 23390 [R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride] (0, 0.01, 0.05, 0.1, 0.5 mg/kg) dose dependently blocked the effect of CRF (1 μg, i.c.v.) on startle at doses that had no effect on baseline startle response. Immunohistochemical studies showed that most CRF-containing cells in the dorsolateral division of the bed nucleus of the stria terminalis (BSTld), part of the critical brain area mediating CRF-enhanced startle, are surrounded by a dense plexus of tyrosine hydroxylase (TH)-positive fibers. Intra-BSTld injections of the retrograde tracer Fluorogold (FG) into the TH field identified neurons in the major dopaminergic areas (A8-A10), but not the major noradrenergic areas [A5, A6 (locus ceruleus), A7], as a significant source of TH-positive innervation. The majority of FG-filled cells double-labeled for TH were found in the dorsocaudal A10 cell group (A10dc) located in the periaqueductal gray area. Together, these data suggest that neuronal regulation of the BSTld by specific dopaminergic pathways and receptors may be an important mechanism for controlling CRF-dependent moods and affective states. These data also suggest that compounds with D1receptor antagonist properties might have anxiolytic-like effects that could be useful for treating conditions associated with hyperactive CRF systems.
Structural Determinants of M-Type KCNQ (Kv7) K+Channel Assembly
Authors: Schwake Michael , Athanasiadu Despina , Beimgraben Christian , Blanz Judith , Beck Christian , Jentsch Thomas J. , Saftig Paul , Friedrich Thomas
Published: April 2006

The ability of KCNQ (Kv7) channels to form hetero-oligomers is of high physiological importance, because heteromers of KCNQ3 with KCNQ2 or KCNQ5 underlie the neuronal M-current, which modulates neuronal excitability. In KCNQ channels, we recently identified a C-terminal subunit interaction (si) domain that determines their subunit-specific assembly. Within thissidomain, there are two motifs that comprise ∼30 amino acid residues each and that exhibit a high probability for coiled-coil formation. Transfer of the first or the second coiled-coil (TCC) domain from KCNQ3 into the KCNQ1 scaffold resulted in chimeras KCNQ1(TCC1)Q3 and KCNQ1(TCC2)Q3, both of which coimmunoprecipitated with KCNQ2. However, only KCNQ1(TCC2)Q3 enhanced KCNQ2 currents and surface expression or exerted a strong dominant-negative effect on KCNQ2. Deletion of TCC2 within KCNQ2 yielded functional homomeric channels but prevented the current augmentation measured after coexpression of KCNQ2 and KCNQ3. In contrast, deleting TCC1 within KCNQ2 did not give functional homomeric KCNQ2 or heteromeric KCNQ2/KCNQ3 channels. Mutations that disrupted the predicted coiled-coil structure of TCC1 in KCNQ2 or KCNQ3 abolished channel activity after expressing these constructs singly or in combination, whereas helix-breaking mutations in TCC2 of KCNQ2 gave functional homomeric channels but prevented the heteromerization with KCNQ3. In contrast, KCNQ3 carrying a coiled-coil disrupting mutation in TCC2 hetero-oligomerized with KCNQ2.

Our data suggest that the TCC1 domains of KCNQ2 and KCNQ3 are required to form functional homomeric as well as heteromeric channels, whereas both TCC2 domains facilitate an efficient transport of heteromeric KCNQ2/KCNQ3 channels to the plasma membrane.
α5GABAAReceptors Mediate the Amnestic But Not Sedative-Hypnotic Effects of the General Anesthetic Etomidate
Authors: Cheng Victor Y. , Martin Loren J. , Elliott Erin M. , Kim John H. , Mount Howard T. J. , Taverna Franco A. , Roder John C. , MacDonald John F. , Bhambri Amit , Collinson Neil , Wafford Keith A. , Orser Beverley A.
Published: April 2006

A fundamental objective of anesthesia research is to identify the receptors and brain regions that mediate the various behavioral components of the anesthetic state, including amnesia, immobility, and unconsciousness. Using complementaryin vivoandin vitroapproaches, we found that GABAAreceptors that contain the α5 subunit (α5GABAARs) play a critical role in amnesia caused by the prototypic intravenous anesthetic etomidate. Whole-cell recordings from hippocampal pyramidal neurons showed that etomidate markedly increased a tonic inhibitory conductance generated by α5GABAARs, whereas synaptic transmission was only slightly enhanced. Long-term potentiation (LTP) of field EPSPs recorded in CA1 stratum radiatum was reduced by etomidate in wild-type (WT) but not α5 null mutant (α5−/−) mice. In addition, etomidate impaired memory performance of WT but not α5−/− mice for spatial and nonspatial hippocampal-dependent learning tasks. The brain concentration of etomidate associated with memory impairmentin vivowas comparable with that which increased the tonic inhibitory conductance and blocked LTPin vitro. The α5−/− mice did not exhibit a generalized resistance to etomidate, in that the sedative-hypnotic effects measured with the rotarod, loss of righting reflex, and spontaneous motor activity were similar in WT and α5−/− mice. Deletion of the α5 subunit of the GABAARs reduced the amnestic but not the sedative-hypnotic properties of etomidate. Thus, the amnestic and sedative-hypnotic properties of etomidate can be dissociated on the basis of GABAAR subtype pharmacology.
An Implicit Plan Overrides an Explicit Strategy during Visuomotor Adaptation
Authors: Mazzoni Pietro , Krakauer John W.
Published: April 2006

The relationship between implicit and explicit processes during motor learning, and for visuomotor adaptation in particular, is poorly understood. We set up a conflict between implicit and explicit processes by instructing subjects to counter a visuomotor rotation using a cognitive strategy in a pointing task. Specifically, they were told the exact nature of the directional perturbation, a rotation that directed them 45° counterclockwise from the desired target, and they were instructed to counter it by aiming for the neighboring clockwise target, 45° away. Subjects were initially successful in completely negating the rotation with this strategy. Surprisingly, however, they were unable to sustain explicit control and made increasingly large errors to the desired target. The cognitive strategy failed because subjects simultaneously adapted unconsciously to the rotation to the neighboring target. Notably, the rate of implicit adaptation to the neighboring target was not significantly different from rotation adaptation in the absence of an opposing explicit strategy. These results indicate that explicit strategies cannot substitute for implicit adaptation to a visuomotor rotation and are in fact overridden by the motor planning system. This suggests that the motor system requires that planned and executed trajectories remain congruous in visual space, and enforces this correspondence even at the expense of an opposing explicit task goal.
Inhibition of Apoptosis by P2Y2Receptor Activation: Novel Pathways for Neuronal Survival
Authors: Arthur David B. , Georgi Sean , Akassoglou Katerina , Insel Paul A.
Published: April 2006

Cell survival is an essential function in the development and maintenance of the nervous system. We demonstrate here a previously unappreciated role for extracellular nucleotide signaling through the P2Y2receptor in the survival of neurons: PC12 (pheochromocytoma 12) cells and dorsal root ganglion neurons are protected from serum starvation-induced apoptosis by ATP, UTP, and ATPγS, an effect mediated via P2Y2receptors, as demonstrated by small interfering RNA and genetic knock-out models. This protection occurs independently of neurophin signaling but requires Src activation of ERK (extracellular signal-regulated kinase) and Akt. Moreover, ATPγS and NGF act synergistically to enhance neuronal survival through enhanced TrkA signaling. The results, which define a novel mechanism for inhibition of apoptosis, implicate parallel, interacting systems—extracellular nucleotides/P2Y2receptors and neurotrophin/TrkA—to sustain neuronal survival.
Deletion of Presenilin 1 Hydrophilic Loop Sequence Leads to Impaired γ-Secretase Activity and Exacerbated Amyloid Pathology
Authors: Deng Yu , Tarassishin Leonid , Kallhoff Verena , Peethumnongsin Erica , Wu Ling , Li Yue-Ming , Zheng Hui
Published: April 2006

γ-Secretase processing of the amyloid precursor protein (APP) generates Aβ40and Aβ42, peptides that constitute the principal components of the β-amyloid plaque pathology of Alzheimer's disease (AD). The γ-secretase activity is executed by a high-molecular-weight complex of which presenilin 1 (PS1) is an essential component. PS1 is a multi-pass membrane protein, and the large hydrophilic loop domain between transmembrane domains 6 and 7 has been shown to interact with various proteins. To determine the physiological function of the loop domain, we created a strain ofPS1knock-in mice in which the exon 10, which encodes most of the hydrophilic loop sequence, was deleted from the endogenousPS1gene. We report here that the homozygous exon 10-deleted mice are viable but exhibit drastically reduced γ-secretase cleavage at the Aβ40, but not the Aβ42, site. Surprisingly, this reduction of Aβ40is associated with exacerbated plaque pathology when expressed onAPPtransgenic background. Thus, the PS1 loop plays a regulatory role in γ-secretase processing, and decreased Aβ40, not increased Aβ42is likely the cause for the accelerated plaque deposition in these animals. Our finding supports a protective role of Aβ40against amyloid pathology and raises the possibility that impaired γ-secretase activity could be the basis for AD pathogenesis in general.
A Transient Receptor Potential Vanilloid 4-Dependent Mechanism of Hyperalgesia Is Engaged by Concerted Action of Inflammatory Mediators
Authors: Alessandri-Haber Nicole , Dina Olayinka A. , Joseph Elizabeth K. , Reichling David , Levine Jon D.
Published: April 2006

The transient receptor potential vanilloid 4 (TRPV4) is a primary afferent transducer that plays a crucial role in neuropathic hyperalgesia for osmotic and mechanical stimuli, as well as in inflammatory mediator-induced hyperalgesia for osmotic stimuli. In view of the clinical importance of mechanical hyperalgesia in inflammatory states, the present study investigated the role of TRPV4 in mechanical hyperalgesia induced by inflammatory mediators and the second-messenger pathways involved. Intradermal injection of either the inflammogen carrageenan or a soup of inflammatory mediators enhanced the nocifensive paw-withdrawal reflex elicited by hypotonic or mechanical stimuli in rat. Spinal administration of TRPV4 antisense oligodeoxynucleotide blocked the enhancement without altering baseline nociceptive threshold. Similarly, inTRPV4−/−knock-out mice, inflammatory soup failed to induce any significant mechanical or osmotic hyperalgesia.In vitroinvestigation showed that inflammatory mediators engage the TRPV4-mediated mechanism of sensitization by direct action on dissociated primary afferent neurons. Additional behavioral observations suggested that multiple mediators are necessary to achieve sufficient activation of the cAMP pathway to engage the TRPV4-dependent mechanism of hyperalgesia. In addition, direct activation of protein kinase A or protein kinase C ϵ, two pathways that mediate inflammation-induced mechanical hyperalgesia, also induced hyperalgesia for both hypotonic and mechanical stimuli that was decreased by TRPV4 antisense and absent inTRPV4−/−mice. We conclude that TRPV4 plays a crucial role in the mechanical hyperalgesia that is generated by the concerted action of inflammatory mediators present in inflamed tissues.
Negotiating and Practicing Performance: An Ethnographic Study of a Musical Open Mic in Brooklyn, New York
Authors: Aldredge Marcus
Published: April 2006

This qualitative study explores amateur musicians and their performance negotiations at a weekly “open mic” in Brooklyn, New York. These musicians and their performance negotiations are juxtaposed against the larger cultural structures of musical scenes and musical art worlds. Opportunities and pathways are few for amateur musicians to practice and negotiate the craft of performance. This study examines the negotiation of the presumed boundaries between musical practice and performance within an open mic scene constructed by and for amateur musicians who are marginal to the larger musical art world.
Broken and Becoming God‐Sized: Contemporary Metal Music and Masculine Individualism
Authors: Rafalovich Adam
Published: April 2006

Using a symbolic interactionist framework, this study is a narrative analysis of song lyrics from sixteen of the most popular heavy metal bands since the early 1990s. The data set for this study constituted 603 songs from fifty‐two long play (LP) recordings. Given that the overwhelming majority of metal music listeners are young males, these data were analyzed as texts of contemporary masculine identity. The contents of the data suggest that such identity is expressed in at least two ways. First, representing the “masculine crisis” identity, the data contain narratives of the self's hopeless domination from subjective and objective forces. Second, narratives representing the “traditional” masculine identity describe the cultivation of inner strength and the consequent conquering of perceived foes. Such narratives often predict the domination of a generic “you” and illustrate how the invocation of the “you” projects a future self. Both of these narratives, which depict either the subjugation or domination of the self, are argued to represent an ideology of individualism.
Heavy Metal Carnival and Dis‐alienation: The Politics of Grotesque Realism
Authors: Halnon Karen Bettez
Published: April 2006

Based on four years of concert fieldwork and extensive music media analysis (including bands such as Cradle of Filth, GWAR, Insane Clown Posse, Marilyn Manson, and Slipknot), this article shows how heavy metal music and its carnival culture express a dis‐alienating politics of resistance. Applying Bakhtin's multifaceted conceptualization of the carnival‐grotesque, the author explains how grotesque realism in metal music and performances constitutes a proto‐utopian liminal alternative to the impersonal, conformist, superficial, unequal, and numbing realities of commercialism and, more abstractly, a resistance to a society of spectacle and nothingness.
The Club DJ: A Semiotic and Interactionist Analysis
Authors: Bakker J. I. (Hans) , Bakker T. R. A. (Theo)
Published: April 2006

Drawing on observation and reflexive introspection, this article analyzes the practice of club DJing and reggae DJing in an attempt to shed light on the semiotic dynamics of music‐making. To understand the historical, semiotic, and interactionist significance of the musical beat in the social world of club reggae DJing, empirical and analytical attention is paid to changes in technology, in aesthetic conventions, and in the meanings of subcultural practices.
Sociology as Public Practice: Toward a Better Utilization of Research and Theory
Authors: Schwartz Pepper
Published: April 2006

This article examines the role of sociologists as public intellectuals. The author discusses the role of the media in disseminating sociological knowledge and the impediments to using it for serious sociological commentary. There are many persuasive reasons why sociology and sociologists should use the language and the medium of the average person and engage in framing the controversies and issues of our time.
“I See Death around the Corner”: Nihilism in Rap Music
Authors: Kubrin Charis E.
Published: April 2006

Rap is one of the most salient music genres of the late twentieth and early twenty-first centuries. Gangsta rap, in particular, with its focus on urban street life, has become a dominant means of expression within contemporary African American adolescent culture. As such, it speaks directly to issues of identity, culture, violence, and nihilism—themes that permeate recent research on inner-city black communities. Mostly ethnographic in nature, this work describes how structural disadvantage, social isolation, and despair create a black youth culture, or street code, that influences adolescent behavior. The current work builds on the community literature by exploring how the street code is present not only on “the street” but also in rap music. It addresses two important questions: (1) To what extent does rap music contain elements of the street code—and particularly nihilism—identified by Anderson (1999) and others? (2) How do rappers experience and interpret their lives, and how do they respond to conditions in their communities? These questions are explored in a content analysis of over four hundred songs on rap albums from 1992 to 2000.
Cowboys and Schoolteachers: Gender in Romance Novels, Secular and Christian
Authors: Clawson Laura
Published: April 2006

This article uses content analysis of 120 novels to consider romance novels as evidence for a particular culture of gender and the family, and as a means of comparing cultural representations of secular and Christian masculinity, femininity, and families. It finds that, although on the surface the texts are most obviously differentiated by religion, gender differences within the religious categories are greater than overall differences between those categories themselves. The most interesting and significant difference between secular and Christian romances emerges in the male hero. Specifically, this analysis finds that secular men are depicted as overwhelmingly strong, economically and physically, but that this strength is frequently overcome by the emotional strength of the heroine, who tames them. Christian heroes, on the other hand, are less overpowering figures at the beginning of the texts but are more dominant within the relationship, subject instead to the will of God.
Food Insufficiency and Depression
Authors: Wu Zheng , Schimmele Christoph M.
Published: April 2006

Using National Population Health Survey data and the stress process model, this study investigates the relationship between food insufficiency and the risk of depression among Canadian adults. The study presents three principal findings. First, after controlling for conventional socioeconomic and socio-demographic variables, food insufficiency increases the risk of depression and actually predicts this risk better than measures of low income, main source of income, and education. Second, the negative effect of food insufficiency is not attributable to social resources disparities, even though these resources significantly reduce the size of the effect. Third, the effects of food insufficiency on depression are generally stronger for women than for men, but the results also indicate that single fathers from food insufficient households face more depression than other groups, including single mothers.
Examining the Adoption of Old-Age Security Programs in the Developing World
Authors: Brown J. Scott
Published: April 2006

This study examines the adoption of income-tested old-age security programs and mandatory privatized security programs in developing nations from 1960 to 1999. Program data on more than one hundred nations are modeled using discrete-time logistic regression. Findings suggest that, for privatized programs, the level of democratization in a nation is an important predictor. Inertia of existing programs and the role of structural adjustment policies in the 1990s are also important in determining the likelihood of program adoptions of this type. For income-tested programs, the number of political strikes experienced by a nation is associated with program adoption. Results suggest that the study of social policy in the developing world is important for understanding processes behind the development of the welfare state.
Effect of Er doping on glass-forming ability of Co50Cr15Mo14C15B6 alloy
Authors: Men H. , Pang S.J. , Zhang T.
Published: April 2006

Bulk glass formation of the Co–Cr–Mo–C–B–Er alloy system was investigated in this paper. The Co50Cr15Mo14C15B6 (at.%) alloy could be cast into fully glassy rod with a diameter up to 2 mm. By adding 2 at.% Er to this alloy, the critical diameter for glass formation reached 10 mm. The excellent glass formability of the Er-doped alloy was mainly attributed to its relatively large reduced glass transition temperature of 0.61, near-eutectic composition, and the necessity of redistribution of the Er atoms for precipitation of crystalline Co6Mo6C phase in the undercooled liquid on cooling.
Electromigration study in the eutectic SnBi solder joint on the Ni/Au metallization
Authors: Chen Long-tai , Chen Chih-ming
Published: April 2006

Microstructural evolution and interfacial reaction in the eutectic SnBi solder joint on the Ni/Au metallization with and without the current stressing of 6.5 × 103 A/cm2 at 70 °C for 5 to 15 days were investigated. Electromigration is found to have significant effects not only on the phase formation at the joint interface but also on the phase coarsening and mass accumulation of Bi in the solder. In the solder joint without the current stressing, only a thin Ni3Sn4 phase was formed at the joint interface. For the solder joint with the current stressing, in addition to the Ni3Sn4 phase, a thick Au–Ni–Bi–Sn phase was formed at the joint interface after 10 days. However, the Au–Ni–Bi–Sn phase was not observed at the anode-side joint interface after 15 days of current stressing. Coarsening of the Bi-rich grain in the solder joint with the current stressing was much faster than that without the current stressing. Mass accumulation of Bi was observed at the anode side of the solder joint with the current stressing and the thickness of the Bi-rich accumulation layer increased with current stressing time. Based on the accumulation rate of the Bi-rich layer and the growth rate of the Bi-rich grain, the product of diffusivity and effective charge number of Bi in the eutectic SnBi solder is calculated to be 4.72 × 10−10 cm2/s.
Comparative study of vertical gradient freeze grown CdTe with variable Sn concentration
Authors: Franc J. , Elhadidy H. , Babentsov V. , Fauler A. , Fiederle M.
Published: April 2006

Four CdTe ingots with gradually increased concentration of the Sn impurity have been grown by the vertical gradient freeze method and were characterized with glow discharge mass spectroscopy, photoinduced current transient spectroscopy, resistivity, photoconductivity, and photoluminescence techniques. It was shown that the Sn impurity strongly influences resistivity and photoconductivity of the material. Concentration of Sn must be higher than the total concentration of residual acceptors to reach strong compensation. The middle-gap donor level pins the Fermi-level. Photoconductive high resistivity material can be prepared with Sn concentrations in the melt in the range 1018–1019 cm−3. In total, 6 electron traps and 3 hole traps were identified in the band gap by several complementary techniques.
Synthesis and microstructural characterization of inorganic fullerene-like MoS2 and graphite-MoS2 hybrid nanoparticles
Authors: Hu J.J. , Sanders J.H. , Zabinski J.S.
Published: April 2006

The structures of inorganic fullerene-like (IF) MoS2 nanoparticles produced by arc discharge in water are reported in this paper. To adjust the chemistry and structure of IF nanoparticles, 2H–MoS2, graphite and composite 2H–MoS2/graphite rods were used as electrodes in the arc synthesis. In comparison to using MoS2 as both anode and cathode, mixed electrodes (graphite and MoS2) significantly increased the discharge current. Various IF-MoS2 nanoparticles were successfully produced by the water-based arc method, and their microstructures were studied using a transmission electron microscope equipped with an x-ray energy dispersive spectrometer. The IF–MoS2 nanoparticles commonly had a solid core wrapped with a few MoS2 layers and exhibit some differences in size and geometry. The IF-MoS2 nanoparticles were typically 5–30 nm in diameter as observed by transmission electron microscopy. Tiny IF-MoS2 nanoparticles (<10 nm) along with fragments of lamellar MoS2 were produced from arc discharge in water using both graphite and MoS2 electrodes. Carbon nano-onions and hybrid nanoparticles consisting of carbon and MoS2 were synthesized by using mixed electrodes of graphite and 2H–MoS2. The hybrid nanoparticles were MoS2 cores covered by a graphite shell. Our results show that the water-based arc method provides a simple tool for producing a variety of nanoparticles including some familiar and some new hybrid structures.
Oxidation-induced copper segregation in Cu60Zr30Ti10 bulk metallic glass
Authors: Tam C.Y. , Shek C.H.
Published: April 2006

Copper segregation in a subsurface layer during annealing of Cu60Zr30Ti10 bulk metallic glass at 773 K under oxygen atmosphere has been investigated by x-ray diffraction, Auger electron spectroscopy, x-ray photoelectron spectroscopy, and scanning electron microscopy. The formation of metallic copper is strongly dependent on the annealing environment. Various oxides with metallic copper are formed after annealing in oxygen atmosphere, but only crystalline intermetallic phases are found under vacuum annealing. Besides, surface characterization results show that the sample annealed in oxygen and vacuum result in enrichment and depletion of Cu on the surface region, respectively.
Vacuum-ultraviolet–vis luminescence of dibarium magnesium orthoborate Ba2Mg(BO3)2 doped with Ce3+ and Eu2+ ions
Authors: Lin Huihong , Liang Hongbin , Tian Zifeng , Su Qiang , Xie Hanyu , Ding Jinfu , Zhang Guobin , Fu Yibing
Published: April 2006

The spectroscopic properties of Ba2Mg(BO3)2:Ce3+ and Ba2Mg(BO3)2:Eu2+ in vacuum-ultraviolet-vis range were investigated. The 5d crystal-field splitting components and the barycenter of Ce3+, the lowest 5d levels, the emission and the Stokes shifts of Eu2+ and Ce3+ in the host lattices, as well as the host-related absorption are identified and discussed in terms of the crystal structure of the host lattice.
Localized heating and fracture criterion for bulk metallic glasses
Authors: Yang B. , Liu C.T. , Nieh T.G. , Morrison M.L. , Liaw P.K. , Buchanan R.A.
Published: April 2006

In this study, we demonstrated that the failure of bulk metallic glasses (BMGs) results from a sudden temperature rise within a shear band. Using a shear transformation zone model, we successfully calculated the temperature within a shear band and found it consistent with the observation from an in situ infrared thermographic system. The instantaneous temperature within a shear band at fracture agrees remarkably well with the glass transition temperature (Tgproviding a new criterion to determine the strength of BMGs from theirTg. This agreement also discloses the fact that catastrophic failure of BMG is caused by the sudden drop in viscosity inside the shear band when the instantaneous temperature within a shear band approachesTg.
Thiolation of carbon nanotubes and sidewall functionalization
Authors: Curran Seamus A. , Cech Jiri , Zhang Donghui , Dewald James L. , Avadhanula Aditya , Kandadai Madhuvanthi , Roth Siegmar
Published: April 2006

We have used transmission electron microscopy to observe the structural changes that have occurred in multi-walled carbon nanotubes (MWCNTs) because of acid treatment. After a thiolation reaction of the acid-treated MWCNTs using P4S10 in refluxing toluene, we have also used electron energy loss spectroscopy to characterize the changes on the nanotubes from sidewall functionalization. We have determined that the sulfur content bonded to the nanotubes is 0.6% in terms of the atomic content of the samples. Raman spectroscopy was used to examine the vibrational changes that occurred to the nanotubes as well as identifying new vibrational modes around 500 cm−1 characteristic of carbon-sulfur bonds.
Effect of volume fraction and geometry of pores on mechanical properties of porous bulk glassy Pd42.5Cu30Ni7.5P20alloys
Authors: Wada Takeshi , Kinaka Makoto , Inoue Akihisa
Published: April 2006

Porous Pd42.5Cu30Ni7.5P20bulk glassy alloy rods with porosities up to 71% were successfully prepared by water quenching in a 15 MPa hydrogen atmosphere, followed by heat treatment in a supercooled liquid state. Pores with sizes up to 80 μm were homogeneously distributed over the whole cross-sectional area. Under compressive deformation, the porous alloys with porosities exceeding 41% did not show macroscopic fracture in a wide compressive strain range up to 0.6. Mechanical tests with porous alloy rods whose pores are anisotropically oriented indicate that the plasticity of the porous alloy is strongly affected by stress concentration factor.
Mechanisms of nanoindentation on single-walled carbon nanotubes: The effect of nanotube length
Authors: Cao Guoxin , Chen Xi
Published: April 2006

The mechanisms of nanoindentation on single-walled carbon nanotubes (SWCNTs) have been studied by using molecular dynamics simulation and continuum analysis during which a flat layer of diamond atoms is pressed down incrementally on a vertically aligned SWCNT. SWCNTs are divided into three distinct categories based on their aspect ratios, such that the nanotube behavior transits from a shell (short tube) to a beam (long tube). Molecular dynamics simulations are used to explore the diverse indentation characteristics in each domain, where the relationships between the strain energy and indentation depth during loading, unloading, and reloading are continuously recorded. The nanoindentation mechanisms are characterized by the critical indentation depth, maximum strain energy and force associated with buckling, as well as with the evolution of carbon bond length and morphology of the SWCNTs. Bifurcation behaviors are explored by investigating the loading-unloading-reloading behaviors of the nanotubes. Parallel finite element simulations are also used to study the pre- and post-buckling behaviors of SWCNT by incorporating the van der Waals interaction into the continuum code. It is found that, for the most part, continuum analysis can effectively capture the overall indentation characteristics, yet some details related to the atomic characteristics of nanoindentation may only be revealed by molecular dynamics simulation. Finally, an indentation mechanism map is derived by comparing behaviors of SWCNTs with different aspect and section ratios. Focusing on the effects of nanotube length, this paper is the first of a series of numerical studies on the indentation mechanisms of carbon nanotubes, which may be used to determine the intrinsic mechanical properties of SWCNTs by means of nanoindentation.
Dynamic electrical properties of polymer-carbon nanotube composites: Enhancement through covalent bonding
Authors: Curran Seamus A. , Zhang Donghui , Wondmagegn Wudyalew T. , Ellis Amanda V. , Cech Jiri , Roth Siegmar , Carroll David L.
Published: April 2006

Composite formation between carbon nanotubes and polymers can dramatically enhance the electrical and thermal properties of the combined materials. We have prepared a composite from polystyrene and multi-walled carbon nanotubes (MWCNT) and, unlike traditional techniques of composite formation, we chose to polymerize styrene from the surface of dithiocarboxylic ester-functionalized MWCNTs to fabricate a unique composite material, a new technique dubbed “gRAFT” polymerization. The thermal stability of the polymer matrix in the covalently linked MWCNT-polystyrene composite is significantly enhanced, as demonstrated by a 15 °C increase of the decomposition temperature than that of the noncovalently linked MWCNT-polystyrene blend. Thin films made from the composite with low MWCNT loadings (<0.9 wt%) are optically transparent, and we see no evidence of aggregation of nanotubes in the thin film or solution. The result from the conductivity measurement as a function of MWCNT loadings suggests two charge transport mechanisms: charge hopping in low MWCNT loadings (0.02–0.6 wt%) and ballistic quantum conduction in high loadings (0.6–0.9 wt%). The composite exhibits dramatically enhanced conductivity up to 33 S m−1 at a low MWCNT loading (0.9 wt%).
Characterization of the functional and growth properties of long-term cell cultures established from a human somatostatinoma
Authors: Galli G , Zonefrati R , Gozzini A , Mavilia C , Martineti V , Tognarini I , Nesi G , Marcucci T , Tonelli F , Tommasi M , Raggi C Casini , Pinzani P , Brandi M L
Published: April 2006

In somatostatinoma, a rare malignant somatostatin (SST)-secreting neoplasia, tumour regression is rarely observed, implying the need for novel antiproliferative strategies. Here, we characterized a long-term culture (SST-secreting cancer (SS-C cells)) established from a human somatostatinoma. High concentrations of SST and chromogranin A were released by SS-C cells and SST release was stimulated by depolarizing stimuli and inhibited by the SST analogue, octreotide. SS-C cells expressed mRNA for SST receptor (SSTR) subtypes 1, 2 and 4, being also able to bind native SST. Moreover, SS-C cells were positively stained with an antibody to SSTR2. SS-C cells also expressed interferon-γ (IFN-γ) receptor mRNA and measurable telomerase activity. Our findings indicate that in vitro exposure of SS-C cells to native SST-28, to octreotide, to IFN-γ, or to 3′-azido-3′deoxythymidine (AZT), a telomerase inhibitor, results in inhibition of SS-C cell proliferation. Concomitant with growth inhibition, apoptosis was detected in SST-, octreotide-, IFN-γ- or AZT-treated SS-C cell cultures. Taken together our results characterized native SST, SST analogues, IFN-γ and a telomerase inhibitor as growth-inhibiting and proapoptotic stimuli in cultured human somatostatinoma cells. Based on these findings, the potential of SST analogues, IFN-γ and AZT, alone or in combination, should be further explored in the medical treatment of somatostatinoma.