bluuebunny/crossref_metadata_2025 huggingface dataset:
Loss of MARCH5 mitochondrial E3 ubiquitin ligase induces cellular senescence through dynamin-related protein 1 and mitofusin 1
Authors: Park Yong-Yea , Lee Seungmin , Karbowski Mariusz , Neutzner Albert , Youle Richard J. , Cho Hyeseong
Published: January 2010

Mitochondria constantly divide and combine through fission and fusion activities. MARCH5, a mitochondrial E3 ubiquitin ligase, has been identified as a molecule that binds mitochondrial fission 1 protein (hFis1), dynamin-related protein 1 (Drp1) and mitofusin 2 (Mfn2), key proteins in the control of mitochondrial fission and fusion. However, how these interactions control mitochondrial dynamics, and cellular function has remained obscure. Here, we show that shRNA-mediated MARCH5 knockdown promoted the accumulation of highly interconnected and elongated mitochondria. Cells transfected with MARCH5 shRNA or a MARCH5 RING domain mutant displayed cellular enlargement and flattening accompanied by increased senescence-associated β-galactosidase (SA-β-Gal) activity, indicating that these cells had undergone cellular senescence. Notably, a significant increase in Mfn1 level, but not Mfn2, Drp1 or hFis1 levels, was observed in MARCH5-depleted cells, indicating that Mfn1 is a major ubiquitylation substrate. Introduction of Mfn1T109A, a GTPase-deficient mutant form of Mfn1, into MARCH5-RNAi cells not only disrupted mitochondrial elongation, but also abolished the increase in SA-β-Gal activity. Moreover, the aberrant mitochondrial phenotypes in MARCH5-RNAi cells were reversed by ectopic expression of Drp1, but not by hFis1, and reversion of the mitochondria morphology in MARCH5-depleted cells was accompanied by a reduction in SA-β-Gal activity. Collectively, our data indicate that the lack of MARCH5 results in mitochondrial elongation, which promotes cellular senescence by blocking Drp1 activity and/or promoting accumulation of Mfn1 at the mitochondria.
Insight of scent: experimental evidence of olfactory capabilities in the wandering albatross (Diomedea exulans)
Authors: Mardon J. , Nesterova A. P. , Traugott J. , Saunders S. M. , Bonadonna F.
Published: January 2010

Wandering albatrosses routinely forage over thousands of kilometres of open ocean, but the sensory mechanisms used in the food search itself have not been completely elucidated. Recent telemetry studies show that some spatial behaviours of the species are consistent with the ‘multimodal foraging strategy’ hypothesis which proposes that birds use a combination of olfactory and visual cues while foraging at sea. The ‘multimodal foraging strategy’ hypothesis, however, still suffers from a lack of experimental evidence, particularly regarding the olfactory capabilities of wandering albatrosses. As an initial step to test the hypothesis, we carried out behavioural experiments exploring the sensory capabilities of adult wandering albatrosses at a breeding colony. Three two-choice tests were designed to investigate the birds' response to olfactory and visual stimuli, individually or in combination. Perception of the different stimuli was assessed by comparing the amount of exploration directed towards an ‘experimental’ display or a ‘control’ display. Our results indicate that birds were able to perceive the three types of stimulus presented: olfactory, visual and combined. Moreover, olfactory and visual cues were found to have additional effects on the exploratory behaviours of males. This simple experimental demonstration of reasonable olfactory capabilities in the wandering albatross supports the ‘multimodal foraging strategy’ and is consistent with recent hypotheses of the evolutionary history of procellariiforms.
Glutamine Is Required for Persistent Epileptiform Activity in the Disinhibited Neocortical Brain Slice
Authors: Tani Hiroaki , Dulla Chris G. , Huguenard John R. , Reimer Richard J.
Published: January 2010

The neurotransmitter glutamate is recycled through an astrocytic–neuronal glutamate–glutamine cycle in which synaptic glutamate is taken up by astrocytes, metabolized to glutamine, and transferred to neurons for conversion back to glutamate and subsequent release. The extent to which neuronal glutamate release is dependent upon this pathway remains unclear. Here we provide electrophysiological and biochemical evidence that in acutely disinhibited rat neocortical slices, robust release of glutamate during sustained epileptiform activity requires that neurons be provided a continuous source of glutamine. We demonstrate that the uptake of glutamine into neurons for synthesis of glutamate destined for synaptic release is not strongly dependent on the system A transporters, but requires another unidentified glutamine transporter or transporters. Finally, we find that the attenuation of network activity through inhibition of neuronal glutamine transport is associated with reduced frequency and amplitude of spontaneous events detected at the single-cell level. These results indicate that availability of glutamine influences neuronal release of glutamate during periods of intense network activity.
Lipreading and Covert Speech Production Similarly Modulate Human Auditory-Cortex Responses to Pure Tones
Authors: Kauramäki Jaakko , Jääskeläinen Iiro P. , Hari Riitta , Möttönen Riikka , Rauschecker Josef P. , Sams Mikko
Published: January 2010

Watching the lips of a speaker enhances speech perception. At the same time, the 100 ms response to speech sounds is suppressed in the observer's auditory cortex. Here, we used whole-scalp 306-channel magnetoencephalography (MEG) to study whether lipreading modulates human auditory processing already at the level of the most elementary sound features, i.e., pure tones. We further envisioned the temporal dynamics of the suppression to tell whether the effect is driven by top-down influences. Nineteen subjects were presented with 50 ms tones spanning six octaves (125–8000 Hz) (1) during “lipreading,” i.e., when they watched video clips of silent articulations of Finnish vowels /a/, /i/, /o/, and /y/, and reacted to vowels presented twice in a row; (2) during a visual control task; (3) during a still-face passive control condition; and (4) in a separate experiment with a subset of nine subjects, during covert production of the same vowels. Auditory-cortex 100 ms responses (N100m) were equally suppressed in the lipreading and covert-speech-production tasks compared with the visual control and baseline tasks; the effects involved all frequencies and were most prominent in the left hemisphere. Responses to tones presented at different times with respect to the onset of the visual articulation showed significantly increased N100m suppression immediately after the articulatory gesture. These findings suggest that the lipreading-related suppression in the auditory cortex is caused by top-down influences, possibly by an efference copy from the speech-production system, generated during both own speech and lipreading.
Quantal Analysis Reveals a Functional Correlation between Presynaptic and Postsynaptic Efficacy in Excitatory Connections from Rat Neocortex
Authors: Hardingham Neil R. , Read Jenny C. A. , Trevelyan Andrew J. , Nelson J. Charmaine , Jack J. Julian B. , Bannister Neil J.
Published: January 2010

At many central synapses, the presynaptic bouton and postsynaptic density are structurally correlated. However, it is unknown whether this correlation extends to the functional properties of the synapses. To investigate this, we made recordings from synaptically coupled pairs of pyramidal neurons in rat visual cortex. The mean peak amplitude of EPSPs recorded from pairs of L2/3 neurons ranged between 40 μV and 2.9 mV. EPSP rise times were consistent with the majority of the synapses being located on basal dendrites; this was confirmed by full anatomical reconstructions of a subset of connected pairs. Over a third of the connections could be described using a quantal model that assumed simple binomial statistics. Release probability (Pr) and quantal size (Q), as measured at the somatic recording site, showed considerable heterogeneity between connections. However, across the population of connections, values ofPrandQfor individual connections were positively correlated with one another. This correlation also held for inputs to layer 5 pyramidal neurons from both layer 2/3 and neighboring layer 5 pyramidal neurons, suggesting that during development of cortical connections presynaptic and postsynaptic strengths are dependently scaled. For 2/3 to 2/3 connections, mean EPSP amplitude was correlated with bothQandPrvalues but uncorrelated withN, the number of functional release sites mediating the connection. The efficacy of a cortical connection is thus set by coordinated presynaptic and postsynaptic strength.
Inositol 1,4,5-Trisphosphate Receptor and dSTIM Function inDrosophilaInsulin-Producing Neurons Regulates Systemic Intracellular Calcium Homeostasis and Flight
Authors: Agrawal Neha , Venkiteswaran Gayatri , Sadaf Sufia , Padmanabhan Nisha , Banerjee Santanu , Hasan Gaiti
Published: January 2010

Calcium (Ca2+) signaling is known to regulate the development, maintenance and modulation of activity in neuronal circuits that underlie organismal behavior. InDrosophila, intracellular Ca2+signaling by the inositol 1,4,5-trisphosphate receptor and the store-operated channel (dOrai) regulates the formation and function of neuronal circuits that control flight. Here, we show that restoring InsP3R activity in insulin-producing neurons of flightless InsP3R mutants (itpr) during pupal development can rescue systemic flight ability. Expression of the store operated Ca2+entry (SOCE) regulator dSTIM in insulin-producing neurons also suppresses compromised flight ability of InsP3R mutants suggesting that SOCE can compensate for impaired InsP3R function. Despite restricted expression of wild-type InsP3R and dSTIM in insulin-producing neurons, a global restoration of SOCE and store Ca2+is observed in primary neuronal cultures from theitprmutant. These results suggest that restoring InsP3R-mediated Ca2+release and SOCE in a limited subset of neuromodulatory cells can influence systemic behaviors such as flight by regulating intracellular Ca2+homeostasis in a large population of neurons through a non-cell-autonomous mechanism.
Serine Racemase Deletion Protects Against Cerebral Ischemia and Excitotoxicity
Authors: Mustafa Asif K. , Ahmad Abdullah S. , Zeynalov Emil , Gazi Sadia K. , Sikka Gautam , Ehmsen Jeffrey T. , Barrow Roxanne K. , Coyle Joseph T. , Snyder Solomon H. , Doré Sylvain
Published: January 2010

d-Serine, formed froml-serine by serine racemase (SR), is a physiologic coagonist at NMDA receptors. Using mice with targeted deletion of SR, we demonstrate a role ford-serine in NMDA receptor-mediated neurotoxicity and stroke. Brain cultures of SR-deleted mice display markedly diminished nitric oxide (NO) formation and neurotoxicity. In intact SR knock-out mice, NO formation and nitrosylation of NO targets are substantially reduced. Infarct volume following middle cerebral artery occlusion is dramatically diminished in several regions of the brains of SR mutant mice despite evidence of increased NMDA receptor number and sensitivity.
Retinophilin Is a Light-Regulated Phosphoprotein Required to Suppress Photoreceptor Dark Noise in Drosophila
Authors: Mecklenburg Kirk L. , Takemori Nobuaki , Komori Naoka , Chu Brian , Hardie Roger C. , Matsumoto Hiroyuki , O'Tousa Joseph E.
Published: January 2010

Photoreceptor cells achieve high sensitivity, reliably detecting single photons, while limiting the spontaneous activation events responsible for dark noise. We used proteomic, genetic, and electrophysiological approaches to characterize Retinophilin (RTP) (CG10233) inDrosophilaphotoreceptors and establish its involvement in dark-noise suppression. RTP possesses membrane occupation and recognition nexus (MORN) motifs, a structure shared with mammalian junctophilins and other membrane-associated proteins found within excitable cells. We show the MORN repeats, and both the N- and C-terminal domains, are required for RTP localization in the microvillar light-gathering organelle, the rhabdomere. RTP exists in multiple phosphorylated isoforms under dark conditions and is dephosphorylated by light exposure. An RTP deletion mutant exhibits a high rate of spontaneous membrane depolarization events in dark conditions but retains the normal kinetics of the light response. Photoreceptors lacking neither inactivation nor afterpotential C (NINAC) myosin III, a motor protein/kinase, also display a similar dark-noise phenotype as the RTP deletion. We show that NINAC mutants are depleted for RTP. These results suggest the increase in dark noise in NINAC mutants is attributable to lack of RTP and, furthermore, defines a novel role for NINAC in the rhabdomere. We propose that RTP is a light-regulated phosphoprotein that organizes rhabdomeric components to suppress random activation of the phototransduction cascade and thus increases the signaling fidelity of dark-adapted photoreceptors.
Variability in Nucleus Accumbens Activity Mediates Age-Related Suboptimal Financial Risk Taking
Authors: Samanez-Larkin Gregory R. , Kuhnen Camelia M. , Yoo Daniel J. , Knutson Brian
Published: January 2010

As human life expectancy continues to rise, financial decisions of aging investors may have an increasing impact on the global economy. In this study, we examined age differences in financial decisions across the adult life span by combining functional neuroimaging with a dynamic financial investment task. During the task, older adults made more suboptimal choices than younger adults when choosing risky assets. This age-related effect was mediated by a neural measure of temporal variability in nucleus accumbens activity. These findings reveal a novel neural mechanism by which aging may disrupt rational financial choice.
A Longitudinal Examination of the Neurodevelopmental Impact of Prenatal Immune Activation in Mice Reveals Primary Defects in Dopaminergic Development Relevant to Schizophrenia
Authors: Vuillermot Stéphanie , Weber Liz , Feldon Joram , Meyer Urs
Published: January 2010

Prenatal exposure to infection is a significant environmental risk factor in the development of schizophrenia and related disorders. Recent evidence indicates that disruption of functional and structural dopaminergic development may be at the core of the developmental neuropathology associated with psychosis-related abnormalities induced by prenatal exposure to infection. Using a mouse model of prenatal immune challenge by the viral mimic polyriboinosinic-polyribocytidilic acid, the present study critically evaluated this hypothesis by longitudinally monitoring the effects of maternal immune challenge during pregnancy on structural and functional dopaminergic development in the offspring from fetal to adult stages of life. Our study shows that prenatal immune challenge leads to dopaminergic maldevelopment starting as early as in the fetal stages of life and produces a set of postnatal dopaminergic abnormalities that is dependent on postnatal maturational processes. Furthermore, our longitudinal investigations reveal a striking developmental correspondence between the ontogeny of specific dopaminergic neuropathology and the postnatal onset of distinct forms of dopamine-dependent functional abnormalities implicated in schizophrenia. Prenatal immune activation thus appears to be a significant environmental risk factor for primary defects in normal dopaminergic development and facilitates the expression of postnatal dopamine dysfunctions involved in the precipitation of psychosis-related behavior. Early interventions targeting the developing dopamine system may open new avenues for a successful attenuation or even prevention of psychotic disorders following neurodevelopmental disruption of dopamine functions.
Reciprocal Modulatory Influences between Tonotopic and Nontonotopic Cortical Fields in the Cat
Authors: Carrasco Andres , Lomber Stephen G.
Published: January 2010

Functional and anatomical studies suggest that acoustic signals are processed hierarchically in auditory cortex. Although most regions of acoustically responsive cortex are not tonotopically organized, all previous electrophysiological investigations of interfield interactions have only examined tonotopically represented areas. The purpose of the present study was to investigate the functional interactions between tonotopically and nontonotopically organized fields in auditory cortex. We accomplished this goal by examining the bidirectional contributions between the cochleotopically organized primary auditory cortex (A1) and the noncochleotopically organized second auditory field (A2). Multiunit acute recording procedures in combination with reversible cooling deactivation techniques were used in eight mature cats. The synaptic activity of A1 or A2 was suppressed while the neuronal response to tonal stimuli of the noninactivated area (A1 or A2) was measured. Response strength, neuronal threshold, receptive field bandwidths, and latency measures were collected at each recorded site before, during, and after cooling deactivation epochs. Our analysis revealed comparable changes in A1 and A2 neuronal response properties. Specifically, significant decreases in neuronal response strength, increases in neuronal threshold, and shortening of response latency were found in both fields during periods of cooling deactivation. The weak anatomical connections between the two fields investigated make these findings unexpected. Furthermore, the observed neuronal changes suggest a model of corticocortical interaction among auditory fields in which neither differences in the magnitude of anatomical projections nor cortical representation of sensory stimuli are reliable determinants of modulatory functions.
Broadband infrared luminescence of Cr3+-doped LiInSiO4 phosphors
Authors: Zhuang Yixi , Luo Jin , Teng Yu , Ye Song , Zhu Bin , Qiu Jianrong
Published: January 2010

Cr3+-doped LiInSiO4 phosphors were prepared by a solid-state reaction method. X-ray diffraction measurement was carried out for crystalline phase identification. Absorption, photoluminescence, excitation, and time-resolved spectra were measured to investigate the optical properties of the phosphors. Two broadband near-infrared emissions centered at 920 and 1172 nm were observed. Time-resolved spectra show that the emission at 1172 nm decays more quickly than the emission at 920 nm. The electron spin resonance spectra exhibit a broad resonance signal at g = 1.96 because of exchange-coupled Cr3+ pairs. The value of Dq/B for low and intermediate crystal fields was evaluated. We suggest that Cr3+ incorporated into different octahedral sites of the crystal is responsible for the different near-infrared luminescence.
Characteristics of copper indium diselenide nanowires embedded in porous alumina templates
Authors: Liu Piao , Singh Vijay P. , Rajaputra Suresh , Phok Sovannary , Chen Zhi
Published: January 2010

Vertically aligned nanowire arrays of copper indium diselenide (CuInSe2 or CIS) of controllable diameter and length were fabricated by simultaneously electrodepositing Cu, In, and Se from an acid bath into the pores of anodized aluminum oxide (AAO) formed on top of an aluminum sheet. X-ray diffraction measurements revealed a preferential [112] orientation and the energy dispersive x-ray analysis (EDX) measurements indicated an overall composition close to stoichiometric CuInSe2. Ohmic contact to CIS was formed by depositing a 100 nm thick of gold layer on top, and thus a Schottky diode device of the Au/CIS nanowires/Al configuration was obtained. Analysis of the current–voltage characteristics of these devices yielded diode ideality factor and reverse saturate current density values slightly higher than those reported in the literature for bulk CIS/Al junctions. Capacitance–voltage measurements were performed on the diodes to get the estimates of space charge density and the junction potential.
Low temperature consolidated lead-free ferroelectric niobate ceramics with improved electrical properties
Authors: Eriksson Mirva , Yan Haixue , Nygren Mats , Reece Mike J. , Shen Zhijian
Published: January 2010

There is a concerted effort to develop lead-free piezoelectric ceramics. (Na0.5K0.5)NbO3-based ceramics have good electrical properties, and are a potential replacement material for lead zirconate titanate piezoelectric ceramics. In this work a commercial powder based on (Na0.5K0.5)NbO3 with an initial particle size of ∼260 nm was consolidated by spark plasma sintering (SPS). To avoid volatilization, high mechanical pressures were used to minimize the densification temperature. It was found that under a uniaxial pressure of 100 MPa, fully densified compacts can be prepared at 850 °C. Ceramics densified at such a low temperature demonstrate an unusually high remanent polarization (30 μC/cm2) and high d33 (146 pC/N). The improved ferroelectric properties are ascribed to the homogeneous, dense, and submicron grained microstructure achieved.
Effect of Ag addition in Sn on growth of SnTe compound during reaction between molten solder and tellurium
Authors: Liao Chien-Neng , Huang Yen-Chun
Published: January 2010

SnTe is the most common compound formed at the bismuth telluride/metal soldered junction of thermoelectric modules. It affects the mechanical and electrical properties of the soldered junction. In the study we investigate the growth of SnTe compound during reaction between molten Sn–3.5Ag solder and tellurium at 250 °C. We found that the growth of SnTe is suppressed by Ag–Te bilayer compounds that block further reaction between liquid Sn and Te. With increasing reaction time, the SnTe morphology becomes rough as a result of coarsening of SnTe grains. The growth of SnTe grains follows the conservative ripening kinetics with the mean particle size proportional to one-third power of reaction time.
3D x-ray microprobe investigation of local dislocation densities and elastic strain gradients in a NiAl-Mo composite and exposed Mo micropillars as a function of prestrain
Authors: Barabash Rozaliya I. , Bei Hongbin , Gao Yanfei , Ice Gene E. , George Easo P.
Published: January 2010

3D spatially-resolved polychromatic microdiffraction was used to nondestructively obtain depth-dependent elastic strain gradients and dislocation densities in the constituent phases of a directionally solidified NiAl–Mo eutectic composite consisting of ∼500–800 nm Mo fibers in a NiAl matrix. Measurements were made before and after the composite was compressed by 5% and 11%. The Mo fibers were analyzed both in their embedded state and after the matrix was etched to expose them as pillars. In the as-grown composite, due to differential thermal contraction during cooldown, the Mo phase is under compression and the NiAl phase is in tension. After the prestrains, the situation is reversed with the Mo phase in tension and NiAl matrix in compression. This result can be explained by taking into account the mismatch in yield strains of the constituent phases and the elastic constraints during unloading. The dislocation density in both the Mo and NiAl phases is found to increase after prestraining. Within experimental uncertainty there is little discernible difference in the total dislocation densities in the Mo phase of the 5% and 11% prestrained specimens. However, the density of the geometrically necessary dislocations and the deviatoric strain gradients increase with increasing prestrain in both the Mo and NiAl phases.
A novel Zr-Ti-Ni-Cu eutectic system with low melting temperature for the brazing of titanium alloys near 800 °C
Authors: Sun Ju-Hyun , Lee Dong-Myoung , Lee Chi-Hwan , Hong Joo-Wha , Shin Seung-Yong
Published: January 2010

This article reports on low (below 800 °C) melting temperature characteristics of a Zr-Ti-Ni-Cu alloy system, designed by adding a small amount of Cu to a Zr-Ti-Ni eutectic alloy system in the Zr-rich corner of the Zr-Ti-Ni system. A series of Zr-Ti-Ni-Cu-based alloy buttons of varying Cu content was fabricated by an arc melting machine. The melting temperature ranges of the quaternary alloys were systematically examined by differential thermal analysis (DTA). As a result, a quaternary eutectic alloy of composition Zr54Ti22Ni16Cu8 with a low melting temperature range from 774 °C to 783 °C was found. In addition, structural and chemical analysis results for the slowly solidified, quaternary eutectic alloy sample revealed equivalent quaternary eutectic structure and phases to those of the ternary eutectic Zr50Ti26Ni24 alloy, except for a small amount of Cu dissolved in individual constituent phases. The wetting angle tested at 800 °C for 60 s on the commercially pure titanium was about 25°.
Room Temperature Ferromagnetism in Spin-coated Anatase- and Rutile- Ti1-x Mx O2 ( M= Fe, Mn, Co) Films
Authors: Barrionuevo Danilo , Singh Surinder P , Tomar Maharaj S.
Published: January 2010

Diluted magnetic semiconductors (DMS) have been explored extensively, because of their potential application in spintronic devices. We studied the structural optical and magnetic properties of Ti1-xMxO2 (M= Fe, Mn, Co; x = 0.00, 0.05, 0.08, 0.10, 0.15, 0.20, 0.25, 0.30), thin films by sol-gel process and deposited using spin coating on Pt (Pt/Ti/SiO2/Si) and quartz substrates. X-ray diffraction studies and Raman spectroscopy reveal anatase and rutile phases of the synthesized films when annealed at 500 and 10000 C, respectively. Optical transmission measurements show high degree of transparency that decreases with increase in transition metal ion concentration. The films show room temperature ferromagnetism, suggesting their potential in spin based heterojunction devices.
Nanotube Crossbar Array via Microcontact Printing for Biomolecule Detection
Authors: Prasad Shalini
Published: January 2010

The paper describes the fabrication and characterization of an ionic junction nanodevice as a biosensor using surfactant coated single walled carbon nanotubes (SWCNT's) via microcontact printing and its application in detecting standard protein biomolecules ( biotin-avidin). Intrinsic semiconducting SWCNT's are doped with anionic and cationic surfactant molecules respectively. Using double patterning process, these ionically doped anionic and cationic semiconducting SWCNT's are alternatively symmetrically patterned in a parallel array to form crossbar junctions onto base microelectrode arrays using flexible polymeric poly-dimethylsiloxane (PDMS) stamps. Parallel alignment of SWCNT's is achieved, due to transfer of the inked SWCNT's from the PDMS relief structure onto the microelectrode array. Base microcontacts on the microelectrode array serve as a platform for measuring electrical characteristics that get modulated due to the biomolecule binding. Functionality of the nanodevice is demonstrated by measuring impedance changes due to biomolecule binding. The modulation of the electrical behavior indicates the existence of potential for using ionically doped nanomaterial systems in fabricating functional building blocks for biosensors.
Photoluminescence from Silver Nanoparticles Enhanced by Surface Plasmon Resonance
Authors: Yeshchenko Oleg A , Dmitruk Igor M. , Alexeenko Alexandr A , Mykhaylo Losytskyy Yu. , Kotko Andriy V. , Pinchuk Anatoliy
Published: January 2010

The size dependence of the photoluminescence spectra from silver nanoparticles embedded in a silica host medium was observed. The quantum yield of the photoluminescence increased when the size of the nanoparticles was decreased. The quantum yield for 8 nm silver nanoparticle was estimated to be on the order of 10-2 which is 108 times higher than the one observed for bulk silver. The two photoluminescence bands observed from silver nanoparticles were rationalized as the radiative electron interband transitions and radiative decay of the surface plasmons in silver nanoparticles. The strong local electric field induced by the surface plasmon resonance in silver nanoparticles enhances the exciting and emitted photons and increases the quantum yield of the photoluminescence.
Good Practice for the Assessment and Safe Handling of Nanomaterials
Authors: Hankin Steve M.
Published: January 2010

Nanotechnology has the potential to greatly improve our lives through medical, environmental and consumer products. Properties at the nanoscale are being exploited in new products, but they could also influence how the particles interact with humans and the environment. There is increasing consensus that for nanotechnology to reach its maximum potential, we must work to understand the hazards and exposure routes in order to minimise the risks. Good practice, founded on the principles of risk assessment and industrial hygiene, are applicable to a wide range of nanomaterials and nanostructured materials including nanoparticles, nanofibres, nanopowders, nanotubes, as well as aggregates and agglomerates of these materials. There is still considerable uncertainty about many aspects of effective risk assessment of nanomaterials, including the hazardous potential of many types of nanoparticles and the levels below which individuals might be exposed, with minimal likelihood of adverse health effects. It is prudent therefore to understand how to develop an appropriate strategy for the risk assessment, handling and disposing of nanomaterials, in the light of known and unknown hazards and exposures. This paper presents a perspective of the key components of risk assessment applicable to nanotechnology and novel materials.
Control and Operation Schemes for Micro-Thermal Conductivity Detectors in Gas Chromatography
Authors: Kaanta Bradley C , Chen Hua , Zhang Xin
Published: January 2010

As the use of sensor networks has expanded, the demand for robust detectors able to operate in a variety of environments has grown. We present the sensitivity testing of a micro thermal conductivity detector (μTCD) operating in two different modes. The microfabricated device we have designed and tested is composed of a resistive heating element suspended in a micro-channel, which creates excellent thermal isolation and a high heat transfer coefficient between the element and the fluid. The sensitivity of a μTCD integrated into a micro-gas chromatography (GC) system, can be increased by a factor of 10 simply by switching between operation in constant temperature and constant voltage modes. This result agrees with the analytical models and testing data previously reported for macro systems and devices.
Multi-Institution Team Teaching (MITT): A Novel Approach to Highly Specialized Graduate Education
Authors: Heffner William R. , Jain Himanshu , Martin Steve W. , Richardson Kathleen , Skaar Eric
Published: January 2010

As engineering becomes more and more specialized, both the faculty resources and number of interested students become limited. Consequently, very frequently highly specialized graduate courses are not offered, especially in disciplines like Materials with small faculty and enrollment. NSF's International Materials Institute for New Functionality in Glass (IMI-NFG) has successfully addressed this problem by successfully introducing the concept of multi-institution team teaching (MITT). It brings together via internet both the expert professors and students from many universities. By pooling the talent of various instructors, the courses become technically stronger and students learn advanced topics that would be available otherwise. As an example, a recent MITT course included instructors from 10 US institutions, and students from many more US and international universities.

Software such as ‘Adobe Connect’ is used for the live delivery of lectures, wherein students can see the instructor and Power Point slides as in a normal classroom. The students may ask questions any time during the lecture, and the instructor would respond immediately. They register and pay tuition at their home institution, so that no exchange of funds is involved between universities. Survey results support that a majority of the enrolled students liked the format and delivery of the course, and more than 75% students felt that multiple instructors, who “taught information of their expertise”, made the course stronger. In conclusion, the concept of MITT has been successfully demonstrated for teaching highly specialized graduate courses.
Self-spreading Lipid Bilayer as Nanofluidic Medium for Micro- and Nanostructured Biosurface Fabrication
Authors: Furukawa Kazuaki , Kashimura Yoshiaki
Published: January 2010

We report on the phenomenology and kinetics of a self-spreading supported lipid bilayer (SLB) on a patterned surface. Analyses of our experiments provided two findings. One is that the self-spreading velocity increased when the SLB reached the inlet of the line patterns. This capillary effect-like behavior indicates an additional attractive interaction for SLB spreading in the line patterns. The other is that the front edge is always normal to the spreading direction even for curving lines. This can be attributed to the line tension at the spreading front edge.
Full-scale testing of a fibre-reinforced concrete footbridge
Authors: Parsekian G. A. , Shrive N. G. , Brown T. G. , Kroman J. , Seibert P. J. , Perry V. H. , Boucher A. , Ghoneim G.
Published: January 2010

The design, testing and construction of a 33·6 m pre-stressed drop-in girder made with Ductal ultra-high performance fibre-reinforced concrete is presented. This girder was part of a pedestrian bridge that required the largest known volume of this material cast in a single pour at the time of production. The girder was post-tensioned and utilised stainless steel rebar at its ends as well as non-corrosive glass fibre reinforced polymer rebar as passive reinforcement. A two-day 90°C steam cure was performed prior to testing. Embedded thermocouples, load cells and displacement transducers were used to instrument two simply supported tests. In the first test, 90% of the factored load was applied, first symmetrically over the top of the slab and secondly eccentrically over half of the top of the slab. The results show that the measured self-weight was close to predicted and displacements were smaller than predicted with full recovery upon load removal, indicating no inelastic behaviour. No cracking was observed during testing or after installation.
Curved bridges: effects of changes of structural system
Authors: Kr˘ístek V. , Vrablik L.
Published: January 2010

A versatile method of analysis of stress variations in horizontally curved prestressed concrete bridges with multiple changes of structural system during construction, respecting the creep and shrinkage effects, conveniently applicable as a tool in design practice, is still not currently available. Unlike straight bridges, the flexural and torsion effects are strongly coupled together in the case of horizontally curved bridges. This is why it is certainly impossible to assess the significance of the torsion effects by simply extrapolating the results obtained for straight structures. The paper presents a developed analytical method for evaluating the effects of changes of a structural system of horizontally curved box girder bridges. To assess influences of various parameters on structural behaviour of horizontally curved bridge girders changing their structural systems, a parametric study was carried out that focused on the effects of the concrete age at which cantilevers are joined; the effects of the bridge curvature upon time variations of bending and torsional moments and the effect of flexural and torsion stiffness ratio.
Elasto-plastic analysis in conventional tunnelling excavation
Authors: Fahimifar A. , Hedayat A. R.
Published: January 2010

A new, rigorous approach for calculating the distribution of stresses and displacements around a circular opening excavated in a strain-softening generalised Hoek–Brown rock mass is presented. As most of the current solutions are relevant to elastic-perfectly plastic and elastic-brittle plastic material, it is worth developing a new analytical-numerical approach to address this end. This paper presents an elasto-plastic solution for the axisymmetrical problem of excavating a circular opening in generalised Hoek–Brown material. In the plastic region it is assumed that all the strength parameters are linear functions of the plastic shear strain. By invoking the Runge–Kutta fourth-order method the problem is solved numerically, and states of stress and displacement in the plastic region are determined. The accuracy and practical application of the proposed approach are shown through several examples. For elastic-perfectly plastic and elastic-brittle plastic cases, the proposed approach shows excellent agreement with closed-form solutions. Similarly, for the strain-softening case, this method is in good agreement with current rigorous methods. The influence of the softening parameter, appearing in the evolution of strength parameters, is examined by the construction of different ground reaction curves, and the influence of different definitions for dilation angle in the plastic region is investigated.
Using Statistical Population Reconstruction to Estimate Demographic Trends in Small Game Populations
Authors: BROMS KRISTIN , SKALSKI JOHN R. , MILLSPAUGH JOSHUA J. , HAGEN CHRISTIAN A. , SCHULZ JOHN H.
Published: January 2010

ABSTRACT Statistical population reconstruction offers a robust approach to demographic assessment for harvested populations, but current methods are restricted to big‐game species with multiple age classes. We extended this approach to small game and analyzed 14 years of age‐at‐harvest data for greater sage‐grouse (Centrocercus urophasianus) in Oregon, USA, in conjunction with radiotelemetry data to reconstruct annual abundance levels, recruitment, and natural survival probabilities. Abundance estimates ranged from a low of 26,236 in 1995 to a high of 39,492 in 2004. Annual abundance estimates for adult males were correlated with a spring lek count index (r= 0.849,P< 0.029). We estimated the average annual harvest mortality for the population to be 0.028, ranging from 0.021 to 0.031 across years. We estimated the probability of natural survival of adult females to be 0.818 (= 0.052), somewhat higher than that of adult males (Ŝ= 0.609,= 0.163). Our precision in reconstructing the population was hampered by low harvest rates and the few birds tagged in the radiotelemetry investigations. Despite these issues, our analysis illustrates how modern statistical reconstruction procedures offer a flexible framework for demographic assessment using commonly collected data. This approach offers a useful alternative to small‐game indices and would be most appropriate for species with 5 or more years of age‐at‐harvest data and moderate‐to‐heavy harvest rates.
The Boar‐Operated‐System: a Novel Method to Deliver Baits to Wild Pigs
Authors: MASSEI GIOVANNA , COATS JULIA , QUY ROGER , STORER KATE , COWAN DAVE P.
Published: January 2010

ABSTRACT Bait‐delivered pharmaceuticals, increasingly used to manage populations of wild boar (Sus scrofa) and feral pigs, may be ingested by nontarget species. Species‐specificity could be achieved through a delivery system. We designed the BOSTM(Boar‐Operated‐System) as a device to deliver baits to wild pigs. The BOSTMconsists of a metal pole onto which a round perforated base is attached. A metal cone with a wide rim slides up and down the pole and fully encloses the base onto which the baits are placed. We conducted a pilot, captive trial and found that captive wild boar fed from the BOSTMeither directly, by lifting the cone, or indirectly, by feeding once another animal had lifted the cone. Thus, we tested whether free‐living wild boar fed from the BOSTMand whether the BOSTMcould prevent bait uptake by nontarget species. We observed that free‐living wild boar fed regularly from the BOSTMand that the device successfully prevented bait uptake by nontarget species. The BOSTMshould be trialed more extensively to confirm its effectiveness and species‐specificity to distribute pharmaceuticals to wild suids. If successful, the BOSTMcould be used to deliver vaccines in disease control programs as well as contraceptives to manage overabundant populations of wild suids.
Cost and Precision Functions for Aerial Quadrat Surveys: a Case Study of Ring‐Necked Ducks in Minnesota
Authors: GIUDICE JOHN H. , FIEBERG JOHN R. , ZICUS MICHAEL C. , RAVE DAVID P. , WRIGHT ROBERT G.
Published: January 2010

ABSTRACT  Cost considerations may be as important as precision when making survey‐design choices, and the ability to accurately estimate survey costs will be essential if survey budgets become more constrained. We used data from a survey of ring‐necked ducks (Aythya collaris) to illustrate how simple distance formulas can be used to construct a cost function for aerial quadrat surveys. Our cost function provided reasonable estimates of effort (hr) and costs, and allowed us to evaluate plot‐size choices in terms of expected cost‐precision tradeoffs. Although factors influencing costs in wildlife surveys can be complicated, we believe that cost functions deserve more attention and should be routinely considered in conjunction with traditional power analyses.
Feeding Ecology of Ring‐Necked Pheasant and Northern Bobwhite Chicks in Conservation Reserve Program Fields
Authors: DOXON ELIZABETH D. , CARROLL JOHN P.
Published: January 2010

ABSTRACT  Gamebird chick survival is dependent on invertebrate availability, and the ability to access insect prey is an important characteristic defining brood habitat quality. Different mixes of warm‐season grasses and forbs were established to improve the habitat quality of fields enrolled in the Conservation Reserve Program (CRP) for gamebirds in the Southern Plains. We analyzed the feeding ecology of human‐imprinted, 4‐ to 10‐day‐old ring‐necked pheasant (Phasianus colchicus) and northern bobwhite (Colinus virginianus) chicks in wheat fields and 4 types of conservation practices (CP) fields enrolled in CRP (CP10, improved CP10, CP2, and CP25) in western Kansas, USA, during June and July, 2004 and 2005. Foraging rates were greatest for bobwhite chicks in improved CP10 and CP25 fields and greatest for pheasant chicks in CP10 and CP25 fields. Vegetation characteristics such as bare ground cover appear to have a significant impact on insect selection, because the diet was more diverse for both species in fields with more bare ground. The CP25 fields provided the best combination of mobility and diet breadth for both species. Although herbicide‐treated wheat fields had low feeding rates, we determined non‐herbicide‐treated fields (i.e., weedy wheat) provided easy mobility and feeding rates similar to CRP fields. We suggest that management of vegetation to benefit gamebirds does not affect species equally. Feeding rates of bobwhite chicks were sensitive to vegetation‐influenced mobility. Management of CRP fields for both pheasant and bobwhite chicks can be reconciled by practices that permit more open space at ground level, such as light disking or burning, to permit easier movement for chicks.
Nest Predation of Greater Sage‐Grouse in Relation to Microhabitat Factors and Predators
Authors: COATES PETER S. , DELEHANTY DAVID J.
Published: January 2010

ABSTRACT  Nest predation is a natural component of greater sage‐grouse (Centrocercus urophasianus) reproduction, but changes in nesting habitat and predator communities may adversely affect grouse populations. We used a 2‐part approach to investigate sage‐grouse nest predation. First, we used information criteria to compare nest survival models that included indices of common raven (Corvus corax) abundance with other survival models that consisted of day of incubation, grouse age, and nest microhabitat covariates using measurements from 77 of 87 sage‐grouse nests. Second, we used video monitoring at a subsample of 55 of 87 nests to identify predators of depredated nests (n = 16) and evaluated the influence of microhabitat factors on the probability of predation by each predator species. The most parsimonious model for nest survival consisted of an interaction between day of incubation and abundance of common ravens (wravenXincubation day = 0.67). An estimated increase in one raven per 10‐km transect survey was associated with a 7.4% increase in the odds of nest failure. Nest survival was relatively lower in early stages of incubation, and this effect was strengthened with increased raven numbers. Using video monitoring, we found the probability of raven predation increased with reduced shrub canopy cover. Also, we found differences in shrub canopy cover and understory visual obstruction between nests depredated by ravens and nests depredated by American badgers (Taxidea taxus). Increased raven numbers have negative effects on sage‐grouse nest survival, especially in areas with relatively low shrub canopy cover. We encourage wildlife managers to reduce interactions between ravens and nesting sage‐grouse by managing raven populations and restoring and maintaining shrub canopy cover in sage‐grouse nesting areas.
Estimating Black Bear Density Using DNA Data From Hair Snares
Authors: GARDNER BETH , ROYLE J. ANDREW , WEGAN MICHAEL T. , RAINBOLT RAYMOND E. , CURTIS PAUL D.
Published: January 2010

ABSTRACT DNA‐based mark‐recapture has become a methodological cornerstone of research focused on bear species. The objective of such studies is often to estimate population size; however, doing so is frequently complicated by movement of individual bears. Movement affects the probability of detection and the assumption of closure of the population required in most models. To mitigate the bias caused by movement of individuals, population size and density estimates are often adjusted using ad hoc methods, including buffering the minimum polygon of the trapping array. We used a hierarchical, spatial capture‐recapture model that contains explicit components for the spatial‐point process that governs the distribution of individuals and their exposure to (via movement), and detection by, traps. We modeled detection probability as a function of each individual's distance to the trap and an indicator variable for previous capture to account for possible behavioral responses. We applied our model to a 2006 hair‐snare study of a black bear (Ursus americanus) population in northern New York, USA. Based on the microsatellite marker analysis of collected hair samples, 47 individuals were identified. We estimated mean density at 0.20 bears/km2. A positive estimate of the indicator variable suggests that bears are attracted to baited sites; therefore, including a trap‐dependence covariate is important when using bait to attract individuals. Bayesian analysis of the model was implemented inWinBUGS, and we provide the model specification. The model can be applied to any spatially organized trapping array (hair snares, camera traps, mist nests, etc.) to estimate density and can also account for heterogeneity and covariate information at the trap or individual level.
White‐Tailed Deer Antler Research: A Critique of Design and Analysis Methodology
Authors: DEMARAIS STEPHEN , STRICKLAND BRONSON K.
Published: January 2010

ABSTRACT  Debate within the popular and technical literature regarding predictability of antler size at maturity based on 1.5‐year antler size in white‐tailed deer (Odocoileus virginianus) has led to confusion and uncertainty within constituent groups. Koerth and Kroll (2008) provided measures of age‐related antler development using recaptures of known‐age males from 12 deer populations in southern Texas. Several design and analysis issues reduce the scope and validity of their conclusion that amount of growth in the first set of antlers was a poor predictor of antler growth at maturity. Although unstated, the statistical hypothesis they tested did not coincide with their specific conclusions. Using a simulation, we show that their methods were susceptible to measurement bias. Their results are applicable only to populations with similar culling and management programs. Additionally, we provide recommendations for future research projects that evaluate predictability of antler size at maturity based on antler size at younger ages.