bluuebunny/crossref_metadata_2025 huggingface dataset:
Phase diagrams of binary mixtures of patchy colloids with distinct numbers and types of patches: The empty fluid regime
Authors: Heras Daniel de las , Tavares José Maria , da Gama Margarida M. Telo
Published: March 2011

We investigate the effect of distinct bonding energies on the onset of criticality of low functionality fluid mixtures. We focus on mixtures of particles with two and three patches as this includes the mixture where “empty” fluids were originally reported. In addition to the number of patches, the species differ in the type of patches or bonding sites. For simplicity, we consider that the patches on each species are identical: one species has three patches of type A and the other has two patches of type B. We have found a rich phase behavior with closed miscibility gaps, liquid–liquid demixing, and negative azeotropes. Liquid–liquid demixing was found to pre-empt the “empty” fluid regime, of these mixtures, when the AB bonds are weaker than the AA or BB bonds. By contrast, mixtures in this class exhibit “empty” fluid behavior when the AB bonds are stronger than at least one of the other two. Mixtures with bonding energies εBB = εAB and εAA < εBB, were found to exhibit an unusual negative azeotrope.
Improved magnetoelectric coupling in Mn and Zn doped CoFe2O4–PbZr0.52Ti0.48O3 particulate composite
Authors: Gupta Arti , Huang A. , Shannigrahi Santiranjan , Chatterjee Ratnamala
Published: March 2011

In this letter, Mn and Zn simultaneously substituted CoFe2O4, Co0.6Zn0.4Fe1.7Mn0.3O4 has been proposed as magnetostrictive component having the maximum in plane piezomagnetic coupling coefficient (q11+q12∼0.070 ppm/Oe) at a field of H∼300 Oe with appreciable saturation values of longitudinal and transverse magnetostriction coefficients (λ11∼−20 ppm and λ12∼10 ppm). On incorporating this in composite (i.e., (x) PbZr0.52Ti0.48O3−(1−x) Co0.6Zn0.4Fe1.7Mn0.3O4) preparation, maximum magnetoelectric voltage coefficients (αE∼122 mV/cm Oe) was obtained in sample x=0.90 at ac magnetic field of amplitude ∼1 Oe and frequency ∼1 kHz.
Nanoscale heterogeneity in alkyl-methylimidazolium bromide ionic liquids
Authors: Aoun Bachir , Goldbach Andreas , González Miguel A. , Kohara Shinji , Price David L. , Saboungi Marie-Louise
Published: March 2011

High-energy x-ray diffraction measurements and atomistic molecular dynamics (AMD) numerical simulations have been carried out on 1-alkyl-3-methylimidazolium bromide ionic liquids, CnmimBr, with n = 2, 4, and 6. Excellent agreement between experiment and simulation is obtained, including the region of the low-Q peak that has proved problematic in previous work in the literature. In the partial structure analysis of the AMD results, a distinct peak develops at the leading edge of the ring–ring pair distribution function and shifts to lower r with increasing alkyl chain length, indicating that the preferential parallel and antiparallel alignment of neighboring cation rings plays a larger role with increasing chain length. The ring–ring, anion–anion, and ring–anion partial structure factors are dominated by strong charge-ordering peaks around 1.1 Å−1, corresponding to a distance between neighboring polar entities of D2 = 5.7 Å. In contrast, the tail–tail S(Q) is dominated by the low-Q peak that rises and moves to lower Q with increasing chain length; the length scale of this structural heterogeneity D1 increases from about 10 Å in C2mimBr to 14.3 Å in C4mimBr and 18.8 Å in C6mimBr. Both the length scale of the structural heterogeneity and its anomalous temperature dependence in the CnmimBr liquids studied here show considerable similarity to results in the literature for CnmimPF6 liquids, indicating a remarkable insensitivity to the form and size of the anion. Our results are consistent with the concept of nanoscale heterogeneity with small, crystal-like moieties.
Configuration interaction study of the ground and excited states of TiO2 ring structures
Authors: Tsuchiya Takashi , Whitten Jerry L.
Published: March 2011

Theoretical studies of the ground and lowest excited singlet and triplet states of a series of titanium dioxide ring structures, (TiO2)2n, n = 3–9, are reported. Calculations are based on many-electron configuration theory, where energies of states and geometrical structures are determined by variational energy minimization. The lowest energy excited states correspond to excitations from oxygen 2p levels to unoccupied 3d orbitals on titanium. For each ring system, two types of excited state solutions are investigated: those that maintain periodic symmetry for individual orbitals and solutions that allow the symmetry to be broken. The latter solutions which correspond to localized states or excitons are found to be significantly lower in energy than the symmetric solutions. We compare the vertical excitation energy of these well-defined geometrical structures with size effects reported in experimental studies.
Resonance modes in arrays of interacting ferromagnetic nanowires subjected to a transverse static magnetic field
Authors: Boucher Vincent , Lacroix Christian , Carignan Louis-Philippe , Yelon Arthur , Ménard David
Published: March 2011

We report the measurement and modeling of two ferromagnetic resonance (FMR) modes in an array of amorphous CoFeB ferromagnetic nanowires with the applied static magnetic field transverse to the nanowire axes. The two modes are observed below saturation and are excited independently by the components of the microwave magnetic field parallel and perpendicular to the static field. We model the magnetization dynamics of the array as arising from the response of two interacting populations of wires magnetized mirror-symmetrically to each other relative to the plane of the array. The theory is well supported by experimental results obtained from vibrating sample magnetometer and shorted waveguide FMR measurements.
The effect of a semiconductor-metal interface on localized terahertz plasmons
Authors: Baron C. A. , Egilmez M. , Straatsma C. J. E. , Chow K. H. , Jung J. , Elezzabi A. Y.
Published: March 2011

We demonstrate the terahertz frequency plasmonic characteristics of a metallic/semiconductor interface. The high-frequency transmission of terahertz radiation through dense ensembles of subwavelength sized Cu/CuxO microparticles via near-field coupling of localized plasmons is shown to increase when a CuxO/Au or CuxO/Pt interface is introduced. This finding introduces a previously undocumented characteristic of plasmonic interaction with material interfaces, and lays the physical groundwork for the integration of plasmonic circuits with traditional semiconductor electronics.
Thermometry based on phonon confinement effect in nanoparticles
Authors: Wang Junwei , Huang Liping
Published: March 2011

Raman spectra of TiO2 nanoparticles (NPs) have a very strong finite-size dependency due to the phonon confinement effect. This provides a convenient way to characterize NPs size by simply using Raman spectroscopy. Together with fast grain growth kinetics and high stability under high temperature and pressure, these NPs have the potential to forensically retain the complete thermal history (temperature and time) of an event that they went through. Here, we demonstrate that both temperature and time can be determined simultaneously by using these thermosensors in the range of 400–700 °C and 5–60 s, assuming that the temperature is constant (a step-function approximation to a thermal spike) during a thermal event.
Appearance of a Debye process at the conductivity relaxation frequency of a viscous liquid
Authors: Richert Ranko , Agapov Alexander , Sokolov Alexei P.
Published: March 2011

The existence of a Debye-type ultraslow process in dielectric spectra of bulk polyalcohols and similar materials has been reported repeatedly in the recent literature. Its loss peak is observed at frequencies that are decades below those of the primary structural relaxation, in a range where the loss signal is usually dominated by dc-conductivity or even electrode polarization. We show that this peak originates from an incomplete filling of the capacitor volume, e.g., as a result of gas bubbles, a situation that gives rise to a Debye process at the conductivity relaxation frequency of the material, where the values of storage and loss components of permittivity are identical. The result implies that these peaks are not endemic to the liquid and can lead to various misinterpretations of the dielectric relaxation spectra. Techniques avoiding the occurrence of such artifacts are discussed.
Medium energy ion scattering of Gr on SiC(0001) and Si(100)
Authors: Copel M. , Oida S. , Kasry A. , Bol A. A. , Hannon J. B. , Tromp R. M.
Published: March 2011

Depth profiling of graphene with high-resolution ion beam analysis is a practical method for analysis of monolayer thicknesses of graphene. Not only is the energy resolution sufficient to resolve graphene from underlying SiC but by use of isotope labeling it is possible to tag graphene generated from reacted ethylene. Furthermore, we are able to analyze graphene supported by oxidized Si(100) substrates, allowing the study of graphene films grown by chemical vapor deposition on metal and transferred to silicon. This introduces a powerful method to explore the fundamentals of graphene formation.
Rotation of a magnetized plasma
Authors: Annaratone B. M. , Escarguel A. , Lefevre T. , Rebont C. , Claire N. , Doveil F.
Published: March 2011

The plasma rotation in the axial magnetic field of the linear machine Mistral [A. Escarguel, Eur. Phys. J. D 56, 209 (2010)] is well described by the assumption that the electrons injected from the source exit radially from the central column and are subject to the Lorentz force. Electrons and ions rotate together by ambipolarity. The solution of the momentum equations foresees correctly the observed radial dependence of the ionic radial velocity measured by laser induced fluorescence. The resolution of these equations is also in good agreement with the measured dependence of the rotation frequency on the applied magnetic field and on the background pressure.
Enhanced Curie temperature in N-deficient GdN
Authors: Plank N. O. V. , Natali F. , Galipaud J. , Richter J. H. , Simpson M. , Trodahl H. J. , Ruck B. J.
Published: March 2011

Polycrystalline GdN thin films have been grown at room temperature with varying N2 pressure. By varying the nitrogen pressure during growth we alter the carrier concentrations of the films. Films grown at low nitrogen pressures display onset of magnetization at temperatures as high as 200 K and a resistivity of 0.3 mΩ cm, whereas films grown at high nitrogen pressures all show a Curie temperature very close to 70 K and resistivity ranges over 1–1000 Ω cm are observed. For all GdN films a peak in the resistivity occurs at TC.
Structure and dynamics of the fast reconnection mechanism in an initially force-free current sheet
Authors: Ugai M.
Published: March 2011

The present paper studies the three-dimensional structure and dynamics of the fast reconnection mechanism in an initially force-free current sheet. A large-scale plasmoid (current sheet bulge) is formed ahead of the Alfvenic fast reconnection jet (ux∼VA) generated in a narrow wedgelike region between a pair of slow shocks. The plasmoid structure is divided into the plasmoid reconnection region P and the plasmoid core region C. In the region P, the strongly sheared reconnected field lines are accumulated and the initial (low-beta) plasma pressure is remarkably enhanced to become comparable to the ambient magnetic pressure since the sheared field lines initially embedded in the current sheet are completely swept away by the reconnection jet. On the other hand, in the region C, the magnetized (low-beta) plasma with the sheared (Bz) field lines, initially embedded in the current sheet, is accumulated without reconnection, and the magnitude of the accumulated sheared field becomes much larger than the ambient magnetic field strength. It is demonstrated that the fast reconnection mechanism in an initially force-free current sheet is so powerful to overcome the magnetic tension forces, which result from the large x-directional bent of the sheared field lines, and vitally proceed by effectively extending the fast reconnection jet region in the sheared field (z) direction.
Temperature stress on pristine ZnO nanowire field effect transistor
Authors: Kim Kyoungwon , Debnath Pulak Chandra , Kim Sangsig , Lee Sang Yeol
Published: March 2011

We have investigated the effect of the temperature dependency on the device stability of pristine ZnO nanowires (NWs) field effect transistor (FET). Pristine ZnO NW FET shows a large threshold voltage (Vth) shift by 6.5 V after increasing the measured temperature from 323 to 363 K. This large shift in Vth is mainly due to thermally activated process. Thermally activated electrons from the deep level trap site can be free carriers which results in the shift in Vth in negative direction. Also, activation energy of ZnO NW FET is derived to be about 1.432 eV based on thermally activated Arrhenius model.
How can warren destruction by ripping control European wild rabbits (Oryctolagus cuniculus) on large properties in the Australian arid zone?
Authors: Berman D. , Brennan M. , Elsworth P.
Published: March 2011

Context
For over 100 years, control efforts have been unable to stop rabbits causing damage to cattle production and native plants and animals on large properties in arid parts of Australia. Warren destruction by ripping has shown promise, but doubts about long-term success and the perceived expense of treating vast areas have led to this technique not being commonly used.

Aims
This study measured the long-term reduction in rabbit activity and calculated the potential cost saving associated with treating just the areas where rabbits are believed to survive drought. We also considered whether ripping should be used in a full-scale rabbit control program on a property where rabbits have been exceptionally resilient to the influence of biological and other control measures.

Methods
Rabbits were counted along spotlight transects before warrens were ripped and during the two years after ripping, in treated and untreated plots. Rabbit activity was recorded to determine the immediate and long-term impact of ripping, up to seven years after treatment. The costs of ripping warrens within different distances from drought refuge areas were calculated.

Key results
Destroying rabbit warrens by ripping caused an immediate reduction in rabbit activity and there were still 98% fewer rabbits counted by spotlight in ripped plots five months after ripping. Seven years after ripping no active warrens were found in ripped plots, whereas 57% of warrens in unripped plots showed signs of rabbit activity. The cost of ripping only the areas where rabbits were likely to seek refuge from drought was calculated to be less than 4% of the cost of ripping all warrens on the property.

Conclusions
Destroying rabbit warrens by ripping is a very effective way of reducing rabbit numbers on large properties in arid Australia. Ripping should commence in areas used by rabbits to survive drought. It is possible that no further ripping will be required.

Implications
Strategic destruction of warrens in drought refuge areas could provide an alternative to biological control for managing rabbits on large properties in the Australian arid zone.
Use of proximity loggers and network analysis to quantify social interactions in free-ranging wild rabbit populations
Authors: Marsh Maija K. , McLeod Steven R. , Hutchings Michael R. , White Piran C. L.
Published: March 2011

Context
Social structure of group-living animals has important implications for processes such as gene flow, information transfer, resource utilisation, and disease spread. However, due to the difficulties associated with measuring relationships among wild animals and deriving meaningful estimates of social structure from these interactions, quantifying sociality of evasive species can be challenging.

Aims
Our aim was to quantify the pattern of social interactions among free-ranging European wild rabbits (Oryctolagus cuniculus) in a temperate region of Australia.

Methods
We used proximity logging devices to collect data on the dyadic interactions among two populations of rabbits. We then applied recently developed social structure and network analytical techniques to infer estimates of sociality and contact networks from recorded interactions.

Key results
We found large heterogeneities in the strength of association indices and network centrality measures within but not between populations. Network analytical techniques revealed clustering of rabbits into distinct social groups.

Conclusions
Most associations within social groups were strong and highly stable over time whereas interactions between groups were rare and transient, indicating low levels of inter-group mixing. Despite the apparent differences in habitat quality between sites, the network characteristics were extremely similar between the two populations.

Implications
Our results highlight the importance of heterogeneities in individual behaviour in determining the dynamics of directly transmitted diseases at the population level.
High levels of the Mps1 checkpoint protein are protective of aneuploidy in breast cancer cells
Authors: Daniel Jewel , Coulter Jonathan , Woo Ju-Hyung , Wilsbach Kathleen , Gabrielson Edward
Published: March 2011

Most human cancers are aneuploid and have chromosomal instability, which contrasts to the inability of human cells to normally tolerate aneuploidy. Noting that aneuploidy in human breast cancer correlates with increased expression levels of the Mps1 checkpoint gene, we investigated whether these high levels of Mps1 contribute to the ability of breast cancer cells to tolerate this aneuploidy. Reducing Mps1 levels in cultured human breast cancer cells by RNAi resulted in aberrant mitoses, induction of apoptosis, and decreased ability of human breast cancer cells to grow as xenografts in nude mice. Remarkably, breast cancer cells that survive reductions in levels of Mps1 have relatively less aneuploidy, as measured by copies of specific chromosomes, compared with cells that have constitutively high levels of Mps1. Thus, high levels of Mps1 in breast cancer cells likely contribute to these cells tolerating aneuploidy.
Identity, regulation, and activity of inducible diterpenoid phytoalexins in maize
Authors: Schmelz Eric A. , Kaplan Fatma , Huffaker Alisa , Dafoe Nicole J. , Vaughan Martha M. , Ni Xinzhi , Rocca James R. , Alborn Hans T. , Teal Peter E.
Published: March 2011

Phytoalexins constitute a broad category of pathogen- and insect-inducible biochemicals that locally protect plant tissues. Because of their agronomic significance, maize and rice have been extensively investigated for their terpenoid-based defenses, which include insect-inducible monoterpene and sesquiterpene volatiles. Rice also produces a complex array of pathogen-inducible diterpenoid phytoalexins. Despite the demonstration of fungal-inducedent-kaur-15-ene production in maize over 30 y ago, the identity of functionally analogous maize diterpenoid phytoalexins has remained elusive. In response to stem attack by the European corn borer (Ostrinia nubilalis) and fungi, we observed the induced accumulation of sixent-kaurane–related diterpenoids, collectively termed kauralexins. Isolation and identification of the predominantRhizopus microsporus-induced metabolites revealedent-kaur-19-al-17-oic acid and the unique analogent-kaur-15-en-19-al-17-oic acid, assigned as kauralexins A3 and B3, respectively. Encoding anent-copalyl diphosphate synthase, fungal-inducedAn2transcript accumulation precedes highly localized kauralexin production, which can eventually exceed 100 μg·g−1fresh weight. Pharmacological applications of jasmonic acid and ethylene also synergize the induced accumulation of kauralexins. Occurring at elevated levels in the scutella of all inbred lines examined, kauralexins appear ubiquitous in maize. At concentrations as low as 10 μg·mL−1, kauralexin B3 significantly inhibited the growth of the opportunistic necrotrophR. microsporusand the causal agent of anthracnose stalk rot,Colletotrichum graminicola. Kauralexins also exhibited significantO. nubilalisantifeedant activity. Our work establishes the presence of diterpenoid defenses in maize and enables a more detailed analysis of their biosynthetic pathways, regulation, and crop defense function.
New host for carbon in the deep Earth
Authors: Boulard Eglantine , Gloter Alexandre , Corgne Alexandre , Antonangeli Daniele , Auzende Anne-Line , Perrillat Jean-Philippe , Guyot François , Fiquet Guillaume
Published: March 2011

The global geochemical carbon cycle involves exchanges between the Earth’s interior and the surface. Carbon is recycled into the mantle via subduction mainly as carbonates and is released to the atmosphere via volcanism mostly as CO
2
. The stability of carbonates versus decarbonation and melting is therefore of great interest for understanding the global carbon cycle. For all these reasons, the thermodynamic properties and phase diagrams of these minerals are needed up to core mantle boundary conditions. However, the nature of C-bearing minerals at these conditions remains unclear. Here we show the existence of a new Mg-Fe carbon-bearing compound at depths greater than 1,800 km. Its structure, based on three-membered rings of corner-sharing (CO
4
)
4-
tetrahedra, is in close agreement with predictions by first principles quantum calculations [Oganov AR, et al. (2008) Novel high-pressure structures of MgCO
3
, CaCO
3
and CO
2
and their role in Earth’s lower mantle.
Earth Planet Sci Lett
273:38–47]. This high-pressure polymorph of carbonates concentrates a large amount of Fe
(III)
as a result of intracrystalline reaction between Fe
(II)
and (CO
3
)
2-
groups schematically written as 4FeO + CO
2
 → 2Fe
2
O
3
 + C. This results in an assemblage of the new high-pressure phase, magnetite and nanodiamonds.
Entropic effect on the rate of dislocation nucleation
Authors: Ryu Seunghwa , Kang Keonwook , Cai Wei
Published: March 2011

Dislocation nucleation is essential to our understanding of plastic deformation, ductility, and mechanical strength of crystalline materials. Molecular dynamics simulation has played an important role in uncovering the fundamental mechanisms of dislocation nucleation, but its limited timescale remains a significant challenge for studying nucleation at experimentally relevant conditions. Here we show that dislocation nucleation rates can be accurately predicted over a wide range of conditions by determining the activation free energy from umbrella sampling. Our data reveal very large activation entropies, which contribute a multiplicative factor of many orders of magnitude to the nucleation rate. The activation entropy at constant strain is caused by thermal expansion, with negligible contribution from the vibrational entropy. The activation entropy at constant stress is significantly larger than that at constant strain, as a result of thermal softening. The large activation entropies are caused by anharmonic effects, showing the limitations of the harmonic approximation widely used for rate estimation in solids. Similar behaviors are expected to occur in other nucleation processes in solids.
Risk preference following adolescent alcohol use is associated with corrupted encoding of costs but not rewards by mesolimbic dopamine
Authors: Nasrallah Nicholas A. , Clark Jeremy J. , Collins Annie L. , Akers Christina A. , Phillips Paul E. , Bernstein Ilene L.
Published: March 2011

Several emerging theories of addiction have described how abused substances exploit vulnerabilities in decision-making processes. These vulnerabilities have been proposed to result from pharmacologically corrupted neural mechanisms of normal brain valuation systems. High alcohol intake in rats during adolescence has been shown to increase risk preference, leading to suboptimal performance on a decision-making task when tested in adulthood. Understanding how alcohol use corrupts decision making in this way has significant clinical implications. However, the underlying mechanism by which alcohol use increases risk preference remains unclear. To address this central issue, we assessed dopamine neurotransmission with fast-scan cyclic voltammetry during reward valuation and risk-based decision making in rats with and without a history of adolescent alcohol intake. We specifically targeted the mesolimbic dopamine system, the site of action for virtually all abused substances. This system, which continuously develops during the adolescent period, is central to both reward processing and risk-based decision making. We report that a history of adolescent alcohol use alters dopamine signaling to risk but not to reward. Thus, a corruption of cost encoding suggests that adolescent alcohol use leads to long-term changes in decision making by altering the valuation of risk.
Viral microRNA target allows insight into the role of translation in governing microRNA target accessibility
Authors: Lin Horng-Ru , Ganem Don
Published: March 2011

It is widely believed that functional mammalian microRNA (miRNA) recognition sequences are located preferentially in the 3' untranslated region (3'UTR) of target mRNAs. Nonetheless, putative miRNA target sites within coding regions have been found at lower frequency in genome-wide studies, and several have been genetically validated. To account for these findings, it has been proposed that translation may inhibit miRNA access to target sites. Here we identify a naturally occurring viral miRNA target that, owing to the compact nature of the viral transcriptome, is situated naturally in the coding region of one transcript and in the 3′UTR of an overlapping mRNA. Examination of the expression of these mRNAs reveals that the cognate miRNA can inhibit expression in both contexts, but inhibition is more potent when the target site is in the UTR. Similarly, forced translation of the target site in the UTR diminished, but did not abolish, its down-regulation by the miRNA. These data affirm that miRNAs can exert regulatory effects on targets within coding regions; however, the dampening of these effects by translation likely accounts for the observed selection for target sites in the 3′UTRs.
Functional inactivation of the rat hippocampus disrupts avoidance of a moving object
Authors: Telensky Petr , Svoboda Jan , Blahna Karel , Bureš Jan , Kubik Stepan , Stuchlik Ales
Published: March 2011

The hippocampus is well known for its critical involvement in spatial memory and information processing. In this study, we examined the effect of bilateral hippocampal inactivation with tetrodotoxin (TTX) in an “enemy avoidance” task. In this paradigm, a rat foraging on a circular platform (82 cm diameter) is trained to avoid a moving robot in 20-min sessions. Whenever the rat is located within 25 cm of the robot's center, it receives a mild electrical foot shock, which may be repeated until the subject makes an escape response to a safe distance. Seventeen young male Long-Evans rats were implanted with cannulae aimed at the dorsal hippocampus 14 d before the start of the training. After 6 d of training, each rat received a bilateral intrahippocampal infusion of TTX (5 ng in 1 μL) 40 min before the training session on day 7. The inactivation severely impaired avoidance of a moving robot (n= 8). No deficit was observed in a different group of rats (n= 9) that avoided a stable robot that was only displaced once in the middle of the session, showing that the impairment was not due to a deficit in distance estimation, object-reinforcement association, or shock sensitivity. This finding suggests a specific role of the hippocampus in dynamic cognitive processes required for flexible navigation strategies such as continuous updating of information about the position of a moving stimulus.
When Less is Heard than Meets the Ear: Change Deafness in a Telephone Conversation
Authors: Fenn Kimberly M. , Shintel Hadas , Atkins Alexandra S. , Skipper Jeremy I. , Bond Veronica C. , Nusbaum Howard C.
Published: March 2011

During a conversation, we hear the sound of the talker as well as the intended message. Traditional models of speech perception posit that acoustic details of a talker's voice are not encoded with the message whereas more recent models propose that talker identity is automatically encoded. When shadowing speech, listeners often fail to detect a change in talker identity. The present study was designed to investigate whether talker changes would be detected when listeners are actively engaged in a normal conversation, and visual information about the speaker is absent. Participants were called on the phone, and during the conversation the experimenter was surreptitiously replaced by another talker. Participants rarely noticed the change. However, when explicitly monitoring for a change, detection increased. Voice memory tests suggested that participants remembered only coarse information about both voices, rather than fine details. This suggests that although listeners are capable of change detection, voice information is not continuously monitored at a fine-grain level of acoustic representation during natural conversation and is not automatically encoded. Conversational expectations may shape the way we direct attention to voice characteristics and perceive differences in voice.
Metabolic status rather than cell cycle signals control quiescence entry and exit
Authors: Laporte Damien , Lebaudy Anne , Sahin Annelise , Pinson Benoît , Ceschin Johanna , Daignan-Fornier Bertrand , Sagot Isabelle
Published: March 2011

Quiescence is defined as a temporary arrest of proliferation, yet it likely encompasses various cellular situations. Our knowledge about this widespread cellular state remains limited. In particular, little is known about the molecular determinants that orchestrate quiescence establishment and exit. Here we show that upon carbon source exhaustion, budding yeast can enter quiescence from all cell cycle phases. Moreover, using cellular structures that are candidate markers for quiescence, we found that the first steps of quiescence exit can be triggered independently of cell growth and proliferation by the sole addition of glucose in both Saccharomyces cerevisiae and Schizosaccharomyces pombe. Importantly, glucose needs to be internalized and catabolized all the way down to glycolysis to mobilize quiescent cell specific structures, but, strikingly, ATP replenishment is apparently not the key signal. Altogether, these findings strongly suggest that quiescence entry and exit primarily rely on cellular metabolic status and can be uncoupled from the cell cycle.
Multiparty quantum secret sharing based on GHZ states
Authors: Hwang Tzonelih , Hwang Cheng-Chieh , Li Chuan-Ming
Published: March 2011

Gao (2009 Commun. Theor. Phys.
52 421–4) has proposed an efficient multiparty quantum secret sharing (MQSS) with two-photon three-dimensional Einstein–Podolsky–Rosen (EPR) pairs. This work shows that a similar idea can also be used to construct an MQSS using the Greenberger–Horne–Zeilinger (GHZ) states. Compared to other MQSSs using GHZ-related states, the newly proposed protocol is more efficient in the aspect of qubit utilization.
On the spontaneous ordering of the mixed-spin Ising square lattice with singly and triply decorated bonds
Authors: Kiššová J , Strečka J
Published: March 2011

The mixed-spin Ising model on a square lattice with singly and triply decorated bonds is exactly solved within the framework of the decoration–iteration transformation, which establishes a precise mapping relationship between the investigated model system and the equivalent spin-1/2 Ising model on an anisotropic square (rectangular) lattice. The effect of uniaxial single-ion anisotropy, which acts on the decorating spin-1 atoms, is examined in particular. It is shown that the investigated model displays a very peculiar critical behaviour as a result of the single-ion anisotropy strengthening because it remains spontaneously long range ordered despite its quasi-1D character in a certain range of single-ion anisotropies before it enters the disordered phase. The single-ion anisotropy parameter is also responsible for diverse temperature dependences of sublattice and total magnetization.
Quantum automorphisms of twisted group algebras and free hypergeometric laws
Authors: Banica Teodor , Bichon Julien , Curran Stephen
Published: March 2011

We prove that we have an isomorphism of type
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper A Subscript a u t Baseline left-parenthesis double-struck upper C Subscript sigma Baseline left-bracket upper G right-bracket right-parenthesis asymptotically-equals upper A Subscript a u t Baseline left-parenthesis double-struck upper C left-bracket upper G right-bracket right-parenthesis Superscript sigma">

A

a
u
t

(

C

σ

[
G
]
)
≃

A

a
u
t

(

C

[
G
]

)
σ

A_{aut}(\mathbb C_\sigma [G])\simeq A_{aut}(\mathbb C[G])^\sigma

, for any finite group

G
G

, and any

2
2

-cocycle

σ
\sigma

on

G
G

. In the particular case

G
=

Z

n
2

G=\mathbb Z_n^2

, this leads to a Haar measure-preserving identification between the subalgebra of

A
o

(
n
)

A_o(n)

generated by the variables

u

i
j

2

u_{ij}^2

and the subalgebra of

A
s

(

n
2

)

A_s(n^2)

generated by the variables

X

i
j

=

∑

a
,
b
=
1

n

p

i
a
,
j
b

X_{ij}=\sum _{a,b=1}^np_{ia,jb}

. Since

u

i
j

u_{ij}

is “free hyperspherical” and

X

i
j

X_{ij}

is “free hypergeometric”, we obtain in this way a new free probability formula, which at

n
=
∞

n=\infty

corresponds to the well-known relation between the semicircle law and the free Poisson law.
Climate forcing and the California Current ecosystem
Authors: King Jacquelynne R. , Agostini Vera N. , Harvey Christopher J. , McFarlane Gordon A. , Foreman Michael G. G. , Overland James E. , Di Lorenzo Emanuele , Bond Nicholas A. , Aydin Kerim Y.
Published: March 2011

King, J. R., Agostini, V. N., Harvey, C. J., McFarlane, G. A., Foreman, M. G. G., Overland, J. E., Di Lorenzo, E., Bond, N. A., and Aydin, K. Y. 2011. Climate forcing and the California Current ecosystem. –ICES Journal of Marine Science, 68: 1199–1216. The Climate Forcing and Marine Ecosystem (CFAME) Task Team of the North Pacific Marine Science Organization (PICES) was formed to address climate forcing impacts on ecosystem structure and productivity of marine species. For the California Current system, the Task Team described the physical processes, built an overview of species across trophic levels, and described how the population dynamics of these species have changed over time. Based on the synthesis work, conceptual models were developed describing the potential pathways linking climate forcing, oceanography, and species' responses. The resultant empirical data scenarios draw on ecosystem histories to provide a synopsis of expected change given global climate change. The multidisciplinary team faced challenges and limitations in their attempt to draw connections between the outputs from global climate models (GCMs), the physical processes, and the subsequent impacts on species via the identified pathways. To some degree, there was a mismatch of variables that fishery scientists identified as important in determining species' response to climate and physical forcing and the variables that current GCMs can now resolve at the regional level. These gaps will be important for researchers to consider as they begin to develop higher-resolution climate and regional oceanographic models for forecasting changes in species' productivity.
C‐Glycosylflavone and Lignan Diglucoside Contents of Commercial, Regular, and Whole‐Wheat Spaghetti
Authors: Hirawan Rhanissa , Beta Trust
Published: March 2011

Consumption of whole‐wheat products, including whole‐wheat spaghetti, is associated with beneficial health effects. Flavonoids and lignans are antioxidant phytochemicals that have received much attention from researchers. Investigations were conducted on the content of flavonoid glycosides, lignan diglucoside, and secoisolariciresinol diglucoside (SDG) as contributors to the health‐promoting properties of whole‐wheat spaghetti. Flavonoid glycosides present in regular and whole‐wheat spaghetti samples were identified as 6‐C‐glucosyl‐8‐C‐arabinosyl apigenin and the sinapic acid ester of apigenin‐C‐diglycoside while, in a previous study, the sinapic acid ester of apigenin‐C‐diglycoside was found only in wheat germ tissues. The content of these compounds was significantly higher in whole‐wheat spaghetti (17.0 and 15.1 μg of apigenin equivalent/g) compared to the regular brands (9.5 and 5.8 μg apigenin equivalent/g). SDG content was also significantly higher in whole‐wheat spaghetti (41.8 μg/g) compared to the regular brands (12.9 μg/g). These findings lend further support to the notion that phenolic compounds, along with dietary fiber, are concentrated in the bran layers of the wheat kernel; hence, consumption of whole grain products is strongly recommended to obtain significant levels of health‐promoting phytochemicals.
Development of Functional Symbiotic White Clover Root Hairs and Nodules Requires Tightly Regulated Production of Rhizobial Cellulase CelC2
Authors: Robledo Marta , Jiménez-Zurdo José I. , Soto M. José , Velázquez Encarnación , Dazzo Frank , Martínez-Molina Eustoquio , Mateos Pedro F.
Published: March 2011

The establishment of rhizobia as nitrogen-fixing endosymbionts within legume root nodules requires the disruption of the plant cell wall to breach the host barrier at strategic infection sites in the root hair tip and at points of bacterial release from infection threads (IT) within the root cortex. We previously found that Rhizobium leguminosarum bv. trifolii uses its chromosomally encoded CelC2 cellulase to erode the noncrystalline wall at the apex of root hairs, thereby creating the primary portal of its entry into white clover roots. Here, we show that a recombinant derivative of R. leguminosarum bv. trifolii ANU843 that constitutively overproduces the CelC2 enzyme has increased competitiveness in occupying aberrant nodule-like root structures on clover that are inefficient in nitrogen fixation. This aberrant symbiotic phenotype involves an extensive uncontrolled degradation of the host cell walls restricted to the expected infection sites at tips of deformed root hairs and significantly enlarged infection droplets at termini of wider IT within the nodule infection zone. Furthermore, signs of elevated plant host defense as indicated by reactive oxygen species production in root tissues were more evident during infection by the recombinant strain than its wild-type parent. Our data further support the role of the rhizobial CelC2 cell wall–degrading enzyme in primary infection, and show evidence of its importance in secondary symbiotic infection and tight regulation of its production to establish an effective nitrogen-fixing root nodule symbiosis.
Acquisition and Transmissibility of U.S. Soybean dwarf virus Isolates by the Soybean Aphid, Aphis glycines
Authors: Damsteegt V. D. , Stone A. L. , Kuhlmann M. , Gildow F. E. , Domier L. L. , Sherman D. J. , Tian B. , Schneider W. L.
Published: March 2011

Soybean dwarf virus (SbDV) exists as several distinct strains based on symptomatology, vector specificity, and host range. Originally characterized Japanese isolates of SbDV were specifically transmitted by Aulacorthum solani. More recently, additional Japanese isolates and endemic U.S. isolates have been shown to be transmitted by several different aphid species. The soybean aphid, Aphis glycines, the only aphid that colonizes soybean, has been shown to be a very inefficient vector of some SbDV isolates from Japan and the United States. Transmission experiments have shown that the soybean aphid can transmit certain isolates of SbDV from soybean to soybean and clover species and from clover to clover and soybean with long acquisition and inoculation access periods. Although transmission of SbDV by the soybean aphid is very inefficient, the large soybean aphid populations that develop on soybean may have epidemiological potential to produce serious SbDV-induced yield losses.
Genetic and Pathogenic Relatedness of Pseudoperonospora cubensis and P. humuli
Authors: Mitchell Melanie N. , Ocamb Cynthia M. , Grünwald Niklaus J. , Mancino Leah E. , Gent David H.
Published: March 2011

The most economically important plant pathogens in the genus Pseudoperonospora (family Peronosporaceae) are Pseudoperonospora cubensis and P. humuli, causal agents of downy mildew on cucurbits and hop, respectively. Recently, P. humuli was reduced to a taxonomic synonym of P. cubensis based on internal transcribed spacer (ITS) sequence data and morphological characteristics. Nomenclature has many practical implications for pathogen identification and regulatory considerations; therefore, further clarification of the genetic and pathogenic relatedness of these organisms is needed. Phylogenetic analyses were conducted considering two nuclear and three mitochondrial loci for 21 isolates of P. cubensis and 14 isolates of P. humuli, and all published ITS sequences of the pathogens in GenBank. There was a consistent separation of the majority of the P. humuli isolates and the P. cubensis isolates in nuclear, mitochondrial, and ITS phylogenetic analyses, with the exception of isolates of P. humuli from Humulus japonicus from Korea. The P. cubensis isolates appeared to contain the P. humuli cluster, which may indicate that P. humuli descended from P. cubensis. Host-specificity experiments were conducted with two reportedly universally susceptible hosts of P. cubensis and two hop cultivars highly susceptible to P. humuli. P. cubensis consistently infected the hop cultivars at very low rates, and sporangiophores invariably emerged from necrotic or chlorotic hypersensitive-like lesions. Only a single sporangiophore of P. humuli was observed on a cucurbit plant during the course of the studies. Together, molecular data and host specificity indicate that there are biologically relevant characteristics that differentiate P. cubensis and P. humuli that may be obfuscated if P. humuli were reduced to a taxonomic synonym of P. cubensis. Thus, we recommend retaining the two species names P. cubensis and P. humuli until the species boundaries can be resolved unambiguously.
Differential Gene Expression During Conidiation in the Grape Powdery Mildew Pathogen, Erysiphe necator
Authors: Wakefield Laura , Gadoury David M. , Seem Robert C. , Milgroom Michael G. , Sun Qi , Cadle-Davidson Lance
Published: March 2011

Asexual sporulation (conidiation) is coordinately regulated in the grape powdery mildew pathogen Erysiphe necator but nothing is known about its genetic regulation. We hypothesized that genes required for conidiation in other fungi would be upregulated at conidiophore initiation or full conidiation (relative to preconidiation vegetative growth and development of mature ascocarps), and that the obligate biotrophic lifestyle of E. necator would necessitate some novel gene regulation. cDNA amplified fragment length polymorphism analysis with 45 selective primer combinations produced ≈1,600 transcript-derived fragments (TDFs), of which 620 (39%) showed differential expression. TDF sequences were annotated using BLAST analysis of GenBank and of a reference transcriptome for E. necator developed by 454-FLX pyrosequencing of a normalized cDNA library. One-fourth of the differentially expressed, annotated sequences had similarity to fungal genes of unknown function. The remaining genes had annotated function in metabolism, signaling, transcription, transport, and protein fate. As expected, a portion of orthologs known in other fungi to be involved in developmental regulation was upregulated immediately prior to or during conidiation; particularly noteworthy were several genes associated with the light-dependent VeA regulatory system, G-protein signaling (Pth11 and a kelch repeat), and nuclear transport (importin-β and Ran). This work represents the first investigation into differential gene expression during morphogenesis in E. necator and identifies candidate genes and hypotheses for characterization in powdery mildews. Our results indicate that, although control of conidiation in powdery mildews may share some basic elements with established systems, there are significant points of divergence as well, perhaps due, in part, to the obligate biotrophic lifestyle of powdery mildews.
The effect of the intra-S-phase checkpoint on origins of replication in human cells
Authors: Karnani Neerja , Dutta Anindya
Published: March 2011

Although many chemotherapy drugs activate the intra-S-phase checkpoint pathway to block S-phase progression, not much is known about how and where the intra-S-phase checkpoint regulates origins of replication in human chromosomes. A genomic analysis of replication in human cells in the presence of hydroxyurea (HU) revealed that only the earliest origins fire, but the forks stall within 2 kb and neighboring clusters of dormant origins are activated. The initiation events are located near expressed genes with a preference for transcription start and end sites, and when they are located in intergenic regions they are located near regulatory factor-binding regions (RFBR). The activation of clustered neo-origins by HU suggests that there are many potential replication initiation sites in permissive parts of the genome, most of which are not used in a normal S phase. Consistent with this redundancy, we see multiple sites bound to MCM3 (representative of the helicase) in the region flanking three out of three origins studied in detail. Bypass of the intra-S-phase checkpoint by caffeine activates many new origins in mid- and late-replicating parts of the genome. The intra-S-phase checkpoint suppresses origin firing after the loading of Mcm10, but before the recruitment of Cdc45 and AND-1/CTF4; i.e., after helicase loading but before helicase activation and polymerase loading. Interestingly, Cdc45 recruitment upon checkpoint bypass was accompanied by the restoration of global Cdk2 kinase activity and decrease in both global and origin-bound histone H3 Lys 4 trimethylation (H3K4me3), consistent with the suggestion that both of these factors are important for Cdc45 recruitment.
Vigilance and grouping in the southern African ground squirrel (Xerus inauris)
Authors: Edwards Sarah , Waterman Jane M.
Published: March 2011

Animals may form groups in response to the foraging–vigilance trade‐off, through enhanced predator detection (collective detection hypothesis) or reduced predation risk to the individual (dilution hypothesis), allowing individuals to decrease vigilance levels. Both hypotheses predict decreasing individual vigilance levels with increasing group size; however, the collective detection hypothesis also predicts increasing overall group vigilance with increasing group size. However, in species in which vigilance and foraging are not mutually exclusive, where vigilance may not be as costly, neither of these hypotheses may apply. Here, we examine the relationship between group size and vigilance in the social Cape ground squirrel (Xerus inauris), a species that can combine foraging and vigilance behaviours. Ten groups were observed using scan sampling, measuring both group and individual vigilance and group size. A negative relationship existed between individual vigilance and group size and a positive relationship between group vigilance and group size. Therefore, in Cape ground squirrels, vigilance seems to be costly even though it can be combined with foraging behaviours. Furthermore, group vigilance behaviour gives support to the collective detection hypothesis, whilst individual vigilance gives support to both hypotheses.