bluuebunny/crossref_metadata_2025 huggingface dataset:
Vibrational dynamics of pyrrole via frequency-domain spectroscopy
Authors: Portnov Alexander , Epshtein Michael , Rosenwaks Salman , Bar Ilana
Published: January 2012

The N–H stretch overtones of pyrrole, a key constituent of biologic building blocks, were studied by room temperature photoacoustic and jet-cooled action spectroscopies to unravel their intramolecular dynamics. Contrary to “isolated” states excited with two and three N–H stretch quanta, the one with four quanta shows strong accidental resonances with two other states involving three quanta of N–H stretch and one quantum of C–H stretch. The inhomogeneously reduced features in the action spectra provide the means for getting insight into the intramolecular interactions and the factors controlling energy flow within pyrrole. The time dependence of the survival probability of the 4ν1 N–H stretch, deduced from the vibrational Hamiltonian, shows an initial decay in ∼0.3 ps with ensuing quantum beats from the N–H – C–H resonance and their decay with a time constant of about 5 ps as a result of weaker coupling to bath states.
Strain gradient induced electric polarization in α-phase polyvinylidene fluoride films under bending conditions
Authors: Baskaran Sivapalan , He Xiangtong , Wang Yu , Fu John Y.
Published: January 2012

The relationship between the applied elastic strain gradient and the induced electric polarization in the α-phase polyvinylidene fluoride films under bending conditions has been investigated. Our experimental studies have shown that the flexoelectric polarization is linearly proportional to the strain gradient and the corresponding direct flexoelectric response is strong. It is reasonable to believe that the physical mechanisms behind the flexoelectric effects in polymers and solid dielectrics are different.
Characteristics of laterally vibrating resonant microcantilevers in viscous liquid media
Authors: Cox Russell , Josse Fabien , Heinrich Stephen M. , Brand Oliver , Dufour Isabelle
Published: January 2012

The characteristics of microcantilevers vibrating laterally in viscous liquid media are investigated and compared to those of similar microcantilevers vibrating in the out-of-plane direction. The hydrodynamic loading on the vibrating beam is first determined using a numerical model. A semi-analytical expression for the hydrodynamic forces in terms of the Reynolds number and the aspect ratio (beam thickness over beam width) is obtained by introducing a correction factor to Stokes’ solution for a vibrating plate of infinite area to account for the effects of the thickness. The results enable the effects of fluid damping and effective fluid mass on the resonant frequency and the quality factor (Q) to be investigated as a function of both the beam’s geometry and liquid medium’s properties and compared to experimentally determined values given in the literature. The resonant frequency and Q are found to be higher for laterally vibrating microcantilevers compared to those of similar geometry experiencing transverse (out-of-plane) vibration. Compared to transversely vibrating beams, the resonant frequency of laterally vibrating beams is shown to decrease at a slower rate (with respect to changes in viscosity) in media having higher viscosities than water. The theoretical results are compared to experimental data obtained for cantilevers completely immersed in solutions of varying aqueous percent glycerol. The increases in resonant frequency and Q are expected to yield much lower limits of detection in liquid-phase chemical sensing applications.
Relative entropy as a measure of inhomogeneity in general relativity
Authors: Akerblom Nikolas , Cornelissen Gunther
Published: January 2012

We introduce the notion of relative volume entropy for two spacetimes with preferred compact spacelike foliations. This is accomplished by applying the notion of Kullback-Leibler divergence to the volume elements induced on spacelike slices. The resulting quantity gives a lower bound on the number of bits which are necessary to describe one metric given the other. For illustration, we study some examples, in particular gravitational waves, and conclude that the relative volume entropy is a suitable device for quantitative comparison of the inhomogeneity of two spacetimes.
Spin-dependent recombination in Czochralski silicon containing oxide precipitates
Authors: Lang V. , Murphy J. D. , Falster R. J. , Morton J. J. L.
Published: January 2012

Electrically detected magnetic resonance is used to identify recombination centers in a set of Czochralski-grown silicon samples processed to contain strained oxide precipitates with a wide range of densities (~1×109 cm-3 to ~7×1010 cm-3). Measurements reveal that photo-excited charge carriers recombine through Pb0 and Pb1 dangling bonds, and comparison to precipitate-free material indicates that these are present at both the sample surface and the oxide precipitates. The electronic recombination rates vary approximately linearly with precipitate density. Additional resonance lines arising from iron-boron and interstitial iron are observed and discussed. Our observations are inconsistent with bolometric heating and interpreted in terms of spin-dependent recombination. Electrically detected magnetic resonance is thus a very powerful and sensitive spectroscopic technique to selectively probe recombination centers in modern photovoltaic device materials.
Optical damage in reduced Z-cut LiNbO3 crystals caused by longitudinal photovoltaic and pyroelectric effects
Authors: Kostritskii S. M. , Aillerie M.
Published: January 2012

The marked optical damage was observed in thin Z-cut plates of the deeply reduced nominally pure LiNbO3 crystals, when a 514.5-nm-laser beam with ordinary polarization was focused on the ±Z face. The longitudinal photovoltaic and pyroelectric effects are shown to be responsible for most of the important peculiarities of the optical damage dynamics. The anisotropy in the behavior between the +Z and −Z faces has been explained by interference of the different kinds of pyroelectric and photovoltaic effects to the space-charge field with an altering relative sign.
Experimental controlling of Fano resonance in indirectly coupled whispering-gallery microresonators
Authors: Li Bei-Bei , Xiao Yun-Feng , Zou Chang-Ling , Jiang Xue-Feng , Liu Yong-Chun , Sun Fang-Wen , Li Yan , Gong Qihuang
Published: January 2012

We experimentally studied the transmission spectrum of a coupled resonator structure in which a low-Q microdisk and a high-Q microtoroid indirectly interact with each other mediated by a fiber taper. Asymmetric Fano resonances were observed and could be controlled to change periodically by adjusting the distance between the two microresonators. It is revealed that the Fano resonance originates from the coupling of the two modes belonging to the two microresonators. The observed period of distance change is around 8 μm, which shows good agreement with the theoretical prediction by the beat of multiple propagating modes in the fiber taper.
Laser direct growth of graphene on silicon substrate
Authors: Wei Dapeng , Xu Xianfan
Published: January 2012

We demonstrate laser direct growth of few layer graphene on a silicon substrate. In our study, a continuous wave laser beam was focused on a poly(methyl methacrylate) (PMMA)-coated silicon wafer to evaporate PMMA and melt the silicon wafer. Carbon atoms, decomposed from PMMA, were absorbed by the molten silicon surface, and then separated from silicon in the cooling process to form few-layer graphene. This Si-catalyzed method will provide a new approach and platform for applications of graphene.
Piezoresistive silicon nanowire based nanoelectromechanical system cantilever air flow sensor
Authors: Zhang Songsong , Lou Liang , Lee Chengkuo
Published: January 2012

We present nanoelectromechanical system based cantilever air flow sensor using silicon nanowires (SiNWs). The cantilever is fabricated in the complementary metal-oxide-semiconductor compatible process with dimension of 90 μm × 20 μm × 3 μm. SiNWs with the size of 2 μm × 90 nm × 90 nm (length × width × height) are embedded at the edge of the cantilever fixed end to experience the maximum air flow induced strain. Compared with recently reported air flow sensors, our device shows a better sensitivity of 198 Ω/m/s and a flow sensing range up to 65 m/s. In addition, improvements in terms of linearity, hysteresis, and lower power consumption are reported as well.
Note: Piezoelectric polymers as transducers for the ultrasonic-reflection method and the application in mechanical property-screening of coatings
Authors: Wegener Michael , Oehler Harald , Lellinger Dirk , Alig Ingo
Published: January 2012

In the last years, non-destructive ultrasonic testing methods are more and more frequently employed in order to investigate the drying and curing processes of different coatings. Among them an ultrasonic reflection method was developed allowing the simultaneous measurement with longitudinal and transversal waves. In order to generate the ultrasonic pulse, piezoelectric ceramics or oxides are usually used as transducer materials which are connected to a delay line. Here, we demonstrate a similar approach for the ultrasonic reflection method installing piezoelectric polymers as ultrasonic transducer materials. In detail, poly(vinylidene fluoride and trifluoroethylene) [P(VDF-TrFE)] copolymers were prepared as piezoelectric transducer layers directly onto the metallization of glass delay lines avoiding additional bonding processes. The film preparation was carried out by solvent casting the polymer onto an area with a diameter of 12 mm and is optimized so that relatively homogeneous polymer layers with thicknesses between 14 and 35 μm are adjusted by the deposited amount of the polymer. Electrical poling renders the polymer piezoelectric. The ultrasonic properties of the P(VDF-TrFE) transducer and their usability for the ultrasonic reflection method are described also in comparison to previous measurements using LiNbO3 transducer.
Cavity ring-down spectroscopy of the oxygen B-band with absolute frequency reference to the optical frequency comb
Authors: Domysławska J. , Wójtewicz S. , Lisak D. , Cygan A. , Ozimek F. , Stec K. , Radzewicz Cz. , Trawiński R. S. , Ciuryło R.
Published: January 2012

Absolute positions of several oxygen B-band lines were measured with the Pound-Drever-Hall-locked frequency-stabilized cavity ring-down spectrometer. The frequency axis of spectra was linked to the optical frequency comb. Achieved uncertainties of line positions are between 0.9 and 2.9 MHz. Self-pressure shifts coefficients are also reported.
Spectral fluctuations of excitonic transitions of InGaAs single quantum dots
Authors: Bak Wan , Noh Haneol , Stambaugh Corey , Arakawa Yasuhiko , Jhe Wonho
Published: January 2012

We report on our experimental study of spectral diffusion in grown InGaAs single quantum dots. Using a double-tapered tip, near-field scanning optical microscope, we obtain the spectral diffusion resulting from the quantum confined Stark effect of individual quantum dots in a randomly fluctuating electric field. These electric fields come from localized charges at defects in the vicinity of the quantum dots. In particular, we find that the similar-patterned temporal jitter, seen in the spectral diffusion, emits from a quantum dot and is dependent on the excitation density and applied bias voltage.
Calculation of the surface tension and pressure components from a non-exponential perturbation method of the thermodynamic route
Authors: Ghoufi A. , Malfreyt P.
Published: January 2012

Surface tension is probably the most important interfacial property and a large number of techniques have been devoted to its calculation. Usually, this calculation is carried out using mechanical or thermodynamic definitions. The mechanical route uses an arbitrary choice to affect the contribution of the pairwise force. To overcome this arbitrariness, a thermodynamic route based on the area perturbation (test-area (TA) method) has been developed for the calculation of surface tension. The volume perturbation (VP) method provides an original route to compute the components of the pressure tensor. These two routes are developed from the perturbation theory leading to working expressions using exponential averages of energy. The use of exponential averages makes the calculation strongly dependent on the occurrence of low values of ΔU. Additionally, the decomposition of the energy to obtain local surface tension is nontrivial. From the explicit derivation of the partition function the exponential average is avoided providing an interesting alternative to TA, VP, and mechanical methods. To make a consistent comparison, we study the profiles of the surface tension along the direction normal to the surface for the different definitions and techniques in the cases of liquid-vapor interfaces of acids gases, binary, and apolar systems.
Propagation of spiking regularity and double coherence resonance in feedforward networks
Authors: Men Cong , Wang Jiang , Qin Ying-Mei , Deng Bin , Tsang Kai-Ming , Chan Wai-Lok
Published: January 2012

We investigate the propagation of spiking regularity in noisy feedforward networks (FFNs) based on FitzHugh-Nagumo neuron model systematically. It is found that noise could modulate the transmission of firing rate and spiking regularity. Noise-induced synchronization and synfire-enhanced coherence resonance are also observed when signals propagate in noisy multilayer networks. It is interesting that double coherence resonance (DCR) with the combination of synaptic input correlation and noise intensity is finally attained after the processing layer by layer in FFNs. Furthermore, inhibitory connections also play essential roles in shaping DCR phenomena. Several properties of the neuronal network such as noise intensity, correlation of synaptic inputs, and inhibitory connections can serve as control parameters in modulating both rate coding and the order of temporal coding.
Performance of a piezoelectric energy harvester driven by air flow
Authors: Kitio Kwuimy C. A. , Litak G. , Borowiec M. , Nataraj C.
Published: January 2012

A turbulent wind source for possible energy harvesting is considered. To increase the amplitude of vibration, we apply a magnetopiezoelastic oscillator having a double well Duffing potential. The output voltage response of the system for different level of wind excitations is analyzed. The energy harvesting appeared to be the most efficient for the conditions close to the stochastic resonance region where the potential barrier was overcame.
Modified Johnson model for ferroelectric lead lanthanum zirconate titanate at very high fields and below Curie temperature
Authors: Narayanan Manoj , Tong Sheng , Ma Beihai , Liu Shanshan , Balachandran Uthamalingam
Published: January 2012

A modified Johnson model is proposed to describe the nonlinear field dependence of the dielectric constant (ɛ-E loop) in ferroelectric materials below the Curie temperature. This model describes the characteristic ferroelectric “butterfly” shape observed in typical ɛ-E loops. The predicted nonlinear behavior agreed well with the measured values in both the low- and high-field regions for lead lanthanum zirconate titanate films. The proposed model was also validated at different temperatures below the ferroelectric-to-paraelectric Curie point. The anharmonic coefficient in the model decreased from 6.142 × 10−19 cm2/V2 to 2.039 × 10−19 cm2/V2 when the temperature increased from 25 °C to 250 °C.
Remanent polarization in a cryptand-polyanion bilayer implemented in an organic field effect transistor
Authors: Wang Xiaodong , Laiho Ari , Berggren Magnus , Crispin Xavier
Published: January 2012

We investigate the possibility to maintain an electric polarization in an organic bilayer via ion trapping, i.e., without any external bias. In the cryptand-polyanion bilayer, ions of specific size can be strongly coordinated with organic macrocyclic molecules. Cations move from the polyanion layer to the cryptand layer upon applying a bias and are trapped in this layer. As a result, the voltage dependence of the polarization displays a hysteresis. The bilayer is then advantageously used as an electronic insulating layer in an organic field effect transistor. The ions trapping and de-trapping can be followed by the amplitude of the threshold voltage (Vth) shift as well as its temporal evolution.
Local charge transfer doping in suspended graphene nanojunctions
Authors: Worne Jeffrey H. , Gullapalli Hemtej , Galande Charudatta , Ajayan Pulickel M. , Natelson Douglas
Published: January 2012

We report electronic transport measurements in nanoscale graphene transistors with gold and platinum electrodes whose channel lengths are shorter than 100 nm and compare them with transistors with channel lengths from 1 μm to 50 μm. We find a large positive gate voltage shift in charge neutrality point (NP) for transistors made with platinum electrodes but negligible shift for devices made with gold electrodes. This is consistent with the transfer of electrons from graphene into the platinum electrodes. As the channel length increases, the disparity between the measured NP using gold and platinum electrodes disappears.
The performance of organic electronic ratchets
Authors: Roeling Erik M. , Germs Wijnand Chr. , Smalbrugge Barry , Geluk Erik Jan , de Vries Tjibbe , Janssen René A. J. , Kemerink Martijn
Published: January 2012

Organic electronic ratchets rectify time-correlated external driving forces, giving output powers that can drive electronic circuitry. In this work their performance characteristics are investigated using numerical modeling and measurements. It is shown how the characteristic parameters of the time–varying asymmetric potential like length scales and amplitude, as well as the density and mobility of the charge carriers in the device influence the performance characteristics. Various ratchet efficiencies and their relations are discussed. With all settings close to optimum, a ratchet with charge displacement and power efficiencies close to 50% and 7% respectively is obtained.
Horizontally-aligned carbon nanotubes arrays and their interactions with liquid crystal molecules: Physical characteristics and display applications
Authors: Roussel Frédérick , Brun Jean-François , Allart Alexandre , Huang Limin , O’Brien Stephen
Published: January 2012

We report on the physical characteristics of horizonthally-grown Single-Walled Carbon Nanotubes (h-al-SWNT) arrays and their potential use as transparent and conducting alignment layer for liquid crystals display devices. Microscopy (SEM and AFM), spectroscopic (Raman) and electrical investigations demonstrate the strong anisotropy of h-al-SWNT arrays. Optical measurements show that h-al-SWNTs are efficient alignment layers for Liquid Crystal (LC) molecules allowing the fabrication of optical wave plates. Interactions between h-al-SWNT arrays and LC molecules are also investigated evidencing the weak azimuthal anchoring energy at the interface, which, in turn, leads to LC devices with a high pretilt angle. The electro-optical reponses of h-al-SWNT/LC cells demonstrate that h-al-SWNT arrays are efficient nanostructured electrodes with potential use for the combined replacement of Indium Tin Oxyde and polymeric alignment layers in conventional displays.
Mitochondrial hexokinase II (HKII) and phosphoprotein enriched in astrocytes (PEA15) form a molecular switch governing cellular fate depending on the metabolic state
Authors: Mergenthaler Philipp , Kahl Anja , Kamitz Anne , van Laak Vincent , Stohlmann Katharina , Thomsen Susanne , Klawitter Heiko , Przesdzing Ingo , Neeb Lars , Freyer Dorette , Priller Josef , Collins Tony J. , Megow Dirk , Dirnagl Ulrich , Andrews David W. , Meisel Andreas
Published: January 2012

The metabolic state of a cell is a key determinant in the decision to live and proliferate or to die. Consequently, balanced energy metabolism and the regulation of apoptosis are critical for the development and maintenance of differentiated organisms. Hypoxia occurs physiologically during development or exercise and pathologically in vascular disease, tumorigenesis, and inflammation, interfering with homeostatic metabolism. Here, we show that the hypoxia-inducible factor (HIF)-1–regulated glycolytic enzyme hexokinase II (HKII) acts as a molecular switch that determines cellular fate by regulating both cytoprotection and induction of apoptosis based on the metabolic state. We provide evidence for a direct molecular interactor of HKII and show that, together with phosphoprotein enriched in astrocytes (PEA15), HKII inhibits apoptosis after hypoxia. In contrast, HKII accelerates apoptosis in the absence of PEA15 and under glucose deprivation. HKII both protects cells from death during hypoxia and functions as a sensor of glucose availability during normoxia, inducing apoptosis in response to glucose depletion. Thus, HKII-mediated apoptosis may represent an evolutionarily conserved altruistic mechanism to eliminate cells during metabolic stress to the advantage of a multicellular organism.
Dynamic autoinoculation and the microbial ecology of a deep water hydrocarbon irruption
Authors: Valentine David L. , Mezić Igor , Maćešić Senka , Črnjarić-Žic Nelida , Ivić Stefan , Hogan Patrick J. , Fonoberov Vladimir A. , Loire Sophie
Published: January 2012

The irruption of gas and oil into the Gulf of Mexico during the
Deepwater Horizon
event fed a deep sea bacterial bloom that consumed hydrocarbons in the affected waters, formed a regional oxygen anomaly, and altered the microbiology of the region. In this work, we develop a coupled physical–metabolic model to assess the impact of mixing processes on these deep ocean bacterial communities and their capacity for hydrocarbon and oxygen use. We find that observed biodegradation patterns are well-described by exponential growth of bacteria from seed populations present at low abundance and that current oscillation and mixing processes played a critical role in distributing hydrocarbons and associated bacterial blooms within the northeast Gulf of Mexico. Mixing processes also accelerated hydrocarbon degradation through an autoinoculation effect, where water masses, in which the hydrocarbon irruption had caused blooms, later returned to the spill site with hydrocarbon-degrading bacteria persisting at elevated abundance. Interestingly, although the initial irruption of hydrocarbons fed successive blooms of different bacterial types, subsequent irruptions promoted consistency in the structure of the bacterial community. These results highlight an impact of mixing and circulation processes on biodegradation activity of bacteria during the
Deepwater Horizon
event and suggest an important role for mixing processes in the microbial ecology of deep ocean environments.
Liquid crystal self-assembly of random-sequence DNA oligomers
Authors: Bellini Tommaso , Zanchetta Giuliano , Fraccia Tommaso P. , Cerbino Roberto , Tsai Ethan , Smith Gregory P. , Moran Mark J. , Walba David M. , Clark Noel A.
Published: January 2012

In biological systems and nanoscale assemblies, the self-association of DNA is typically studied and applied in the context of the evolved or directed design of base sequences that give complementary pairing, duplex formation, and specific structural motifs. Here we consider the collective behavior of DNA solutions in the distinctly different regime where DNA base sequences are chosen at random or with varying degrees of randomness. We show that in solutions of completely random sequences, corresponding to a remarkably large number of different molecules, e.g., approximately 10
12
for random 20-mers, complementary still emerges and, for a narrow range of oligomer lengths, produces a subtle hierarchical sequence of structured self-assembly and organization into liquid crystal (LC) phases. This ordering follows from the kinetic arrest of oligomer association into long-lived partially paired double helices, followed by reversible association of these pairs into linear aggregates that in turn condense into LC domains.
Testing the Utility of an Adaptive Cluster Sampling Method for Monitoring a Rare and Imperiled Darter
Authors: Davis Johnathan G. , Cook S. Bradford , Smith David D.
Published: January 2012

Adaptive cluster sampling (ACS) designs were tested against simple random sampling (SRS) designs to determine whether ACS designs were more suitable sampling protocols for monitoring rare fish species. To test the utility of these designs, baseline data on the tuxedo darter Etheostoma lemniscatum (a rare, federally endangered fish) were collected at three sites on the Big South Fork of the Cumberland River and used in computer simulation of ACS designs. Based on the simulation models, five ACS designs were chosen and tested at 13 potential monitoring sites. In terms of efficiency, ACS designs performed better than SRS designs, providing estimates with smaller standard errors. Adaptive cluster sampling design efficiency increased with effort; therefore, the two goals—minimizing effort and maximizing accuracy—are incompatible. Because it had less error, an inverse ACS design was recommended, although it required more sampling effort than other designs. Factors possibly affecting overall design performance include the sample size, neighborhood configuration, and habitat complexity of sampling sites. This study was the first to implement ACS for rare and endangered stream-dwelling fishes and provided methodologies for pilot testing and selecting appropriate ACS designs for an imperiled fish species. Adaptive cluster sampling designs are best suited for monitoring imperiled fishes that exhibit a more-clustered spatial distribution. Population estimates from ACS designs using underwater observation provide quantitative data from standardized protocols that are applicable to long-term monitoring of imperiled fishes.

Received May 21, 2010; accepted June 21, 2011
Refining and Applying a Maximum-Count Aerial-Access Survey Design to Estimate the Harvest Taken from New Zealand's Largest Recreational Fishery
Authors: Hartill Bruce W. , Watson Tim G. , Bian Richard
Published: January 2012

We used a maximum-count aerial-access survey design to estimate the 12-month recreational harvest of snapper Chrysophrys (Pagrus) auratus (also known as squirefish) taken by New Zealand's largest recreational fishery. To provide a count of all boats fishing on a given day, the spatial extent of the 3,800-km2 Hauraki Gulf embayment was surveyed from the air on a random stratified selection of survey days at the approximate time of maximum effort. Anglers were also censused at a subset of the available access points on the same day. The ratio of the aerial count to the number of interviewed parties who claimed to have fished at the time of the overflight was used to expand the observations of landed catch and to estimate the total catch taken by all fishers returning to all access points. Pairing an aerial count with a creel-survey-derived profile of effort on each survey day provides two advantages. First, only one flight is required to estimate the overall level of effort on each day, which is beneficial given the costs of operating aircraft. Second, the relationship between these two data sources can be used to estimate the level of effort and harvest on all survey days, including those days when flights are cancelled due to low clouds or other nonrandom events. This approach is currently the preferred harvest estimation approach in New Zealand, and it has since been used to assess the snapper harvest from management areas with coastlines in excess of 2,000 km long.

Received February 7, 2011; accepted July 28, 2011
Effect of Rainbow Trout Size on Response to Rotenone and Antimycin
Authors: Brown Peter J. , Johnson Heather , Zale Alexander V.
Published: January 2012

The piscicides rotenone and antimycin are commonly used to eradicate unwanted fish populations. However, the relationships (if present) between their toxicities and fish sizes are unknown and could be especially important when bioassay fish are used to detect piscicide presence and effectiveness. Size-mediated toxicity could lead to either excessive or inadequate piscicide applications if bioassay fish are larger or smaller than the fish being eradicated. The relationships between time to death and weight of rainbow trout Oncorhynchus mykiss (0.7–574.0 g) at an antimycin concentration of 7.5 μg/L and a rotenone concentration of 12.5 μg/L were determined. Antimycin took significantly longer than rotenone to kill rainbow trout at concentrations typically used in eradication projects. Significant positive relationships existed between fish size and time to death for rotenone and antimycin exposures and were probably caused by size-mediated differences in metabolic rate; however, these relationships accounted for less than 21% of the variation in time to death. Smaller fish appeared to be affected by the chemicals more quickly, but their deaths did not consistently occur before the deaths of larger fish.

Received March 12, 2011; accepted August 4, 2011
First Report of Natural Infection of Pea (Pisum sativum) by Tomato spotted wilt virus in Hungary
Authors: Salamon P. , Nemes K. , Salánki K. , Palkovics L.
Published: January 2012

In June of 2009, stem vascular necrosis, interveinal necrosis of upper leaves, wilting of flowers, and necrotic spots on the pods were observed on garden pea (Pisum sativum L. ‘Rajnai törpe’) in northeast Hungary. A mechanical transmissible plant virus designated Ps091 was isolated from leaves of severely affected plants. Pathological investigations demonstrated that Ps091 had a host range very similar to that of Tomato spotted wilt virus (TSWV). It caused necrotic local lesions on Chenopodium spp. and induced systemic yellowing and necrosis on the upper leaves of Nicotiana benthamiana, N. clevelandii, and N. glutinosa by mechanical inoculation. Typical symptoms of TSWV infection appeared on the top leaves of pepper (Capsicum annuum L. ‘Albaregia’) and tomato (Solanum lycopersicum ‘Kecskeméti 3’) inoculated with Ps091. For molecular identification, total nucleic acids were extracted from Ps091-infected tobacco with a standard phenol-chloroform extraction method (2), and reverse transcription-PCR was conducted with TSWV N-gene specific, own designed primers (TSWV-S for: 5′-CCCAGCATTATGGCAAGCC-3′, TSWV-S rev: 5′-TGATCTGGTCGAGGTTTTCCGCTAGCCC-3′). A tobacco plant infected with a reference pepper isolate, TSWV-Ca1 (1), and a healthy tobacco plant served as positive and negative controls, respectively. An approximately 300-bp DNA fragment was amplified from tobacco infected with Ps091 and TSWV-Ca1. The Ps091 amplicon was cloned, sequenced in both directions, and the sequence was deposited in GenBank (Accession No. HQ615692). Blast search analysis showed that TSWV-Ps091 had the highest identity (99%) with TSWV-P170RB strain (GenBank Accession No. DQ431238) in the cognate region. Since the latter isolate is a resistance breaking (RB) strain on pepper, pathogenicity of Ps091 on TSWV resistant pepper and tomato lines was studied. Mechanically inoculated pepper (C. annuum × C. chinense TSR F4 line) and tomato (S. lycopersicum ‘Stevens’) genotypes carrying the Tsw and Sw5 resistance genes, respectively, reacted with necrotic local lesions, but no systemic infections were detected by applying bioassays to N. clevelandii. These results demonstrate that Ps091 does not belong to the RB strains of TSWV. Back inoculations to pea (‘Rajnai törpe’) resulted in necrotic local spots as well as systemic stem and top necrosis, proving the causal relationship between TSWV-Ps091 and the pea disease observed in the field. Although TSWV has been known to cause epidemy in solanaceous crops and tobacco, to our knowledge, this is the first report of its natural occurrence on a legume plant, particularly on pea in Hungary. Because of the extreme severity of the disease caused on pea and high infection pressure, TSWV is a new threat to pea production in this country, where pea is a very important crop.

References: (1) P. Salamon et al. Page 23 in: Plant Protection Days. Budapest, February, 2010. (2) J. L. White and J. M. Kaper. J. Virol. Methods 23:83, 1989.
Long‐chain PUFA in Granulocytes, Mononuclear Cells, and RBC in Patients With Cystic Fibrosis
Authors: Jørgensen Marianne H. , Ott Peter , Michaelsen Kim F. , Porsgaard Trine , Jensen Fleming , Lanng Susanne
Published: January 2012

Background and Aim:

Patients with cystic fibrosis (CF) have low levels of n‐3 long‐chain polyunsaturated fatty acids (n‐3 LCPUFA) in plasma or red blood cells (RBC), as also seen in other chronic and acute liver diseases. The differences may be more pronounced in CF transmembrane conductance regulator protein (CFTR)‐regulated tissues such as granulocytes, monocytes, and lymphocytes. The aim of the present study was to investigate whether patients with CF‐related liver disease have lower n‐3 LCPUFA level than patients with CF without liver disease.

Methods:

Twenty patients with known CF‐related liver disease were matched with 20 CF patients without. Blood samples were analysed for liver biochemistry and haematology. Granulocytes, mononuclear cells, and RBC were separated by density gradient centrifugation, and fatty acid composition was measured by gas chromatography. Hepatic ultrasound was scored according to Williams et al. Hepatic transit time (HTT) was measured with the ultrasound contrast agent SonoVue.

Results:

No significant differences were seen in either n‐6 or n‐3 LCPUFAs in any cell line when the 2 groups were compared. In a multiple regression analysis including HTT, age, Pseudomonas aeruginosa infection, diabetes mellitus, treatment with ursodeoxycholic acid, forced expiratory volume in 1 second (% of predicted value), and Williams' ultrasound scoring scale, only n‐3 LCPUFA docosahexaenoic acid in mononuclear cell membranes was positively associated with HTT (P = 0.02). The arachidonic acid/docosahexaenoic acid ratio within the mononuclear cells was negatively associated with both HTT (P = 0.003) and Williams' ultrasound scoring scale (P = 0.03). For RBC‐LCPUFAs, no significant associations were seen.

Conclusions:

These findings indicate that in patients with CF, the degree of liver disease was negatively associated with LCPUFA n‐3 levels in CFTR‐expressing white blood cells but unrelated to those levels in CFTR‐negative RBC.
Feasibility of Using MR Enterography for the Assessment of Terminal Ileitis and Inflammatory Activity in Children With Crohn Disease
Authors: Silverstein Jared , Grand David , Kawatu David , Shah Samir A. , Steinkeler Jill , LeLeiko Neal
Published: January 2012

Background and Objective:

Radiation exposure increases cancer risk in children with Crohn disease (CD). Magnetic resonance enterography (MRE) can image the gastrointestinal tract without exposure to radiation. The aim of the present study was to determine whether our MRE protocol could diagnose terminal ileitis and the degree of inflammatory activity in children with CD.

Methods:

Retrospective review of patients 18 years of age or younger who underwent MRE for known or suspected CD from June 15, 2007 to April 1, 2010. MRE was performed with Volumen and water as oral contrast and gadolinium‐based intravenous contrast. No antiperistaltic agent was used. Each MRE was compared with ileal biopsies obtained within 90 days. Severity of inflammation on MRE was scored and compared with the Pediatric Crohn Disease Activity Index (PCDAI).

Results:

Seventy‐two patients underwent 80 MREs during the study period. Forty‐two of the 72 patients (58.3%) underwent colonoscopy within 90 days of MRE, and the terminal ileum was intubated in 33. Compared with histology, MRE had a sensitivity of 71.4% and a specificity of 100% for terminal ileitis. The positive and negative predictive values were 100% and 70%, respectively. PCDAI was calculated in 39 of the 72 patients (54.2%) and had a statistically significant positive correlation with MRE score of 0.37 (P = 0.020426).

Conclusions:

In children with known or suspected CD, our MRE protocol has a high specificity and positive predictive value for terminal ileitis. Severity of inflammation on MRE had a statistically significant positive correlation with PCDAI.
Kaleidoscopic tilings, networks and hierarchical structures in blends of 3-miktoarm star terpolymers
Authors: Kirkensgaard Jacob Judas Kain
Published: January 2012

Dissipative particle dynamics simulations are used to explore blends of 3-miktoarm star terpolymers. The investigated system is a 50/50 blend of ABC and ABD stars, which is investigated as a function of composition and at different symmetric segregation levels. The study shows that in analogy to pure ABC star melts cylindrical tiling patters form, but now in four-coloured variants. Also, a large part of the phase diagram is dominated by multi-coloured network structures showing hierarchical features. Most prominently, a novel alternating gyroid network structure with a hyperbolic lamellar interface is predicted to form. Here, the two gyroidal nets are composed of respectively C and D components, with the minority A and B components forming the lamellar-like curved structure on the dividing interface between the two nets.
Co‐occurrence of sexual risk behaviors and substance use across emerging adulthood: evidence for state‐ and trait‐level associations*
Authors: King Kevin M. , Nguyen Hong V. , Kosterman Rick , Bailey Jennifer A. , Hawkins J. David
Published: January 2012

Aims  Prior research has suggested that problematic alcohol and drug use are related to risky sexual behaviors, either due to trait‐level associations driven by shared risk factors such as sensation seeking or by state‐specific effects, such as the direct effects of substance use on sexual behaviors. Although the prevalence of both high‐risk sexual activity and alcohol problems decline with age, little is known about how the associations between substance use disorder symptoms and high‐risk sexual behaviors change across young adulthood.

Design setting and participants  Using a community sample (n = 790) interviewed every 3 years from age 21 to age 30 years, we tested trait‐ and state‐level associations among symptoms of alcohol and drug abuse and dependence and high‐risk sexual behaviors across young adulthood using latent growth curve models.

Measurements  We utilized diagnostic interviews to obtain self‐report of past‐year drug and alcohol abuse and dependence symptoms. High‐risk sexual behaviors were assessed with a composite of four self‐reported behaviors.

Findings  Results showed time‐specific associations between alcohol disorder symptoms and risky sexual behaviors (r = 0.195, P < 0.001), but not associations between their trajectories of change. Conversely, risky sexual behaviors and drug disorder symptoms were associated only at the trait level, not the state level, such that the levels and rate of change over time of both were correlated (r = 0.35, P < 0.001).

Conclusions  High‐risk sexual behaviors during young adulthood seem to be driven both by trait and state factors, and intervention efforts may be successful if they are either aimed at high‐risk individuals or if they work to disaggregate alcohol use from risky sexual activities.
Lack of effect of tofacitinib (CP‐690,550) on the pharmacokinetics of the CYP3A4 substrate midazolam in healthy volunteers: confirmation of in vitro data
Authors: Gupta Pankaj , Alvey Christine , Wang Rong , Dowty Martin E. , Fahmi Odette A. , Walsky Robert L. , Riese Richard J. , Krishnaswami Sriram
Published: January 2012

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

• Tofacitinib (CP‐690,550) is a novel, oral Janus kinase inhibitor being investigated as a targeted immunomodulator and disease‐modifying therapy in rheumatoid arthritis.

• Non‐renal elimination accounts for 70% of the total clearance of tofacitinib and the metabolism is primarily mediated by cytochrome P450 (CYP) 3A4.

• This study was required to determine the effect of tofacitinib on the in vivo pharmacokinetics of a sensitive CYP3A4 substrate.

WHAT THIS STUDY ADDS

• The pharmacokinetics of midazolam, a sensitive CYP3A4 substrate, are not altered when co‐administered with tofacitinib in healthy subjects.

• Tofacitinib is unlikely to affect the clearance of drugs metabolized by CYP enzymes.

• There is no need for dose adjustments of CYP substrates when co‐administered with tofacitinib.

AIMS To investigate inhibitive and inductive effects of tofacitinib (CP‐690,550), a Janus kinase inhibitor, on CYP3A4 function via in vitro and in vivo studies.

METHODS In vitro experiments were conducted to assess the inhibition and induction potential of tofacitinib for major drug metabolizing enzymes (CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6 and CYP3A4). A phase 1, randomized, open‐label, two‐way crossover study (NCT00902460) was conducted to confirm the lack of inhibitive/inductive effect on a sensitive CYP3A4 substrate, midazolam, in healthy subjects. Midazolam pharmacokinetics were assessed over 24 h following single dose 2 mg administration prior to administering tofacitinib and after twice daily dosing of tofacitinib 30 mg for 6 days. The primary endpoint was midazolam area under the concentration–time profile, from time 0 to infinity (AUC(0,∞)).

RESULTS In vitro studies demonstrated low potential for CYP inhibition (IC50 estimates tofacitinib >30 µm), CYP3A4 mRNA induction (observed at tofacitinib concentrations ≥25 µm) and no effect on enzymatic activity of CYP substrates. In the human study, AUC(0,∞) adjusted geometric mean ratio for midazolam plus tofacitinib to midazolam alone was 103.97% [90% confidence interval (CI) 95.57, 113.12], wholly within the pre‐specified acceptance region (80, 125). The 90% CI for the ratio of adjusted geometric means of maximum plasma concentration (Cmax) (95.98, 108.87) was also wholly within this acceptance region.

CONCLUSIONS These data confirm a lack of an inhibitive or inductive effect of tofacitinib on CYP3A activity in humans and, in conjunction with in vitro data, support the conclusion that tofacitinib is unlikely to influence the CYP enzyme system as a whole.
Burkitt lymphoma and the discovery of Epstein–Barr virus
Authors: Epstein Anthony
Published: January 2012

The chance germinal encounter with the first lecture outside Africa on Burkitt lymphoma is described together with the hypothesis of a viral cause. Repeated virological investigations on lymphoma biopsies proved negative, leading to the idea that a latent virus might be activated if lymphoma cells could be cultured, although no human lymphoid cell had at that time ever been maintained in vitro. A chance event reminding of the need for suspension culture with mouse lymphomas led to success. The cultured cells carried a morphologically unequivocal, strangely inert, herpesvirus shown later to be immunologically, biologically and biochemically unique. How this new agent acquired its name, Epstein–Barr virus, is explained.
Viral infections and human cancers: the legacy of Denis Burkitt
Authors: Harford Joe B.
Published: January 2012

Denis Parsons Burkitt was born in 1911, and in the late 1950s, described the disease that has come to be known as Burkitt lymphoma based on cases he observed in Uganda. Subsequently, Burkitt lymphoma was recognized as the first human tumour associated with an infectious agent when Epstein–Barr virus was isolated from samples supplied by Burkitt. It is now recognized that over one‐quarter of cancers worldwide are tied to infections. Notably, liver cancer is linked to hepatitis B virus and hepatitis C virus infections, and cervical cancer to infections involving the human papilloma viruses. In addition, immunocompromise arising from infection with the human immunodeficiency virus allows tumours (e.g., Kaposi sarcoma) caused by other viruses to arise. More than 50 years after the seminal paper by Burkitt based on his work in Africa, it is appreciated that the contribution of viral infections to cancers remains considerably higher in sub‐Saharan Africa than in the rest of the world.
Ammonia may play an important role in the succession of cyanobacterial blooms and the distribution of common algal species in shallow freshwater lakes
Authors: Dai Guo‐Zheng , Shang Jin‐Long , Qiu Bao‐Sheng
Published: January 2012

With the human intensification of agricultural and industrial activities, large amount of reduced nitrogen enter into the biosphere, which consequently results in the development of global eutrophication and cyanobacterial blooms. However, no research had reported the effect of ammonia toxicity on the algal succession. In this study, we investigated the ammonia toxicity to 19 algal species or strains to test the hypothesis that ammonia may regulate the succession of cyanobacterial blooms and the distribution of common algal species in freshwater lakes. The bloom‐forming cyanobacterium Microcystis aeruginosa PCC 7806 suffered from ammonia toxicity at high pH value and light intensity conditions. Low NH4Cl concentration (0.06 mmol L−1) resulted in the decrease of operational PSII quantum yield by 50% compared with the control exposed to 1000 μmol photons m−2 s−1 for 1 h at pH 9.0 ± 0.2, which can be reached in freshwater lakes. Furthermore, the tolerant abilities to NH3 toxicity of 18 freshwater algal species or strains were as follows: hypertrophication species > eutrophication species > mesotrophication species > oligotrophication species. The different sensitivities of NH3 toxicity in this study could well explain the distributing rule of common algal species in the freshwater lakes of different trophic states. Meanwhile, the cyanobacterial bloom (e.g. M. aeruginosa) always happened at the low concentration of ammonia in summer, and disappeared with the decrease of ammonia. This may be attributed to the toxic effect of ammonia to M. aeruginosa in spring (the average and maximum ammonia concentration were 0.08 and 0.72 mmol L−1 in 33 Chinese lakes), and the low level of NH3‐N in summer and fall in the lakes might be used as preferred nitrogen nutrition by M. aeruginosa, rather than with toxicity. Therefore, ammonia could be a key factor to determine the distribution of common algal species and cyanobacterial bloom in the freshwater systems.
Consistent effects of nitrogen amendments on soil microbial communities and processes across biomes
Authors: Ramirez Kelly S. , Craine Joseph M. , Fierer Noah
Published: January 2012

Ecosystems worldwide are receiving increasing amounts of reactive nitrogen (N) via anthropogenic activities with the added N having potentially important impacts on microbially mediated belowground carbon dynamics. However, a comprehensive understanding of how elevated N availability affects soil microbial processes and community dynamics remains incomplete. The mechanisms responsible for the observed responses are poorly resolved and we do not know if soil microbial communities respond in a similar manner across ecosystems. We collected 28 soils from a broad range of ecosystems in North America, amended soils with inorganic N, and incubated the soils under controlled conditions for 1 year. Consistent across nearly all soils, N addition decreased microbial respiration rates, with an average decrease of 11% over the year‐long incubation, and decreased microbial biomass by 35%. High‐throughput pyrosequencing showed that N addition consistently altered bacterial community composition, increasing the relative abundance of Actinobacteria and Firmicutes, and decreasing the relative abundance of Acidobacteria and Verrucomicrobia. Further, N‐amended soils consistently had lower activities in a broad suite of extracellular enzymes and had decreased temperature sensitivity, suggesting a shift to the preferential decomposition of more labile C pools. The observed trends held across strong gradients in climate and soil characteristics, indicating that the soil microbial responses to N addition are likely controlled by similar wide‐spread mechanisms. Our results support the hypothesis that N addition depresses soil microbial activity by shifting the metabolic capabilities of soil bacterial communities, yielding communities that are less capable of decomposing more recalcitrant soil carbon pools and leading to a potential increase in soil carbon sequestration rates.