bluuebunny/crossref_metadata_2025 huggingface dataset:
On the specific identity of specimens ofPhytoseiulus longipesEvans (Mesostigmata: Phytoseiidae) showing different feeding behaviours: morphological and molecular analyses
Authors: Tixier M.-S. , Ferrero M. , Okassa M. , Guichou S. , Kreiter S.
Published: February 2010

This paper focuses on the differentiation of specimens, identified asPhytoseiulus longipes, collected in four countries: Argentina, Brazil, Chile and South Africa. Two of these populations are known to feed and develop onTetranychus evansi, whereas the two others do not. As morphologically similar specimens can sometimes belong to different species and because differences in predatory behaviours exist among the four populations considered, we tested for the presence of cryptic species. Morphological and molecular experiments (12S rDNA) were carried out. The four studied populations ofP. longipescould be morphologically differentiated thanks to a combination of characters. However, these morphological differences are very small. The two populations that feed and develop onT. evansi(from Argentina and Brazil) are morphologically closer to each other than to the two other populations. Genetic distances among the four populations ofP. longipeswere very low, suggesting that despite their different feeding habits, all specimens belong to the same species. However, the populations associated withT. evansishowed some genetic differentiation from those that do not use this pest. This is the first time that this type of differentiation has been reported for the family Phytoseiidae. These results are of primary importance to ensure the success of biological control programs and to develop strains adapted to both crops and prey species.
Beyond antioxidants: the cellular and molecular interactions of flavonoids and how these underpin their actions on the brain
Authors: Spencer Jeremy P. E.
Published: February 2010

The consumption of flavonoid-rich foods and beverages has been suggested to limit the neurodegeneration associated with a variety of neurological disorders and to prevent or reverse normal or abnormal deteriorations in cognitive performance. Flavonoids mediate these effects via a number of routes, including a potential to protect neurons against injury induced by neurotoxins, an ability to suppress neuroinflammation and a potential to promote memory, learning and cognitive function. Originally, it was thought that such actions were mediated by the antioxidant capacity of flavonoids. However, their limited absorption and their low bioavailability in the brain suggest that this explanation is unlikely. Instead, this multiplicity of effects appears to be underpinned by three separate processes: first, through their interactions with important neuronal and glial signalling cascades in the brain, most notably the phosphatidylinositol 3-kinase/Akt and mitogen-activated protein kinase pathways that regulate pro-survival transcription factors and gene expression; second, through an ability to improve peripheral and cerebral blood flow and to trigger angiogenesis and neurogenesis in the hippocampus; third, by their capacity to directly react with and scavenge neurotoxic species and pro-inflammatory agents produced in the brain as a result of both normal and abnormal brain ageing. The present review explores the potential inhibitory or stimulatory actions of flavonoids within these three systems and describes how such interactions are likely to underlie neurological effects.
Central carbon metabolism ofLeishmaniaparasites
Authors: SAUNDERS ELEANOR C. , DE SOUZA DAVID P. , NADERER THOMAS , SERNEE MARIJKE F. , RALTON JULIE E. , DOYLE MARIA A. , MACRAE JAMES I. , CHAMBERS JENNY L. , HENG JOANNE , NAHID AMSHA , LIKIC VLADIMIR A. , MCCONVILLE MALCOLM J.
Published: February 2010

Leishmaniaspp. are sandfly-transmitted protozoa parasites that cause a spectrum of diseases in humans. Many enzymes involved inLeishmaniacentral carbon metabolism differ from their equivalents in the mammalian host and are potential drug targets. In this review we summarize recent advances in our understanding ofLeishmaniacentral carbon metabolism, focusing on pathways of carbon utilization that are required for growth and pathogenesis in the mammalian host. WhileLeishmaniacentral carbon metabolism shares many features in common with other pathogenic trypanosomatids, significant differences are also apparent.Leishmaniaparasites are also unusual in constitutively expressing most core metabolic pathways throughout their life cycle, a feature that may allow these parasites to exploit a range of different carbon sources (primarily sugars and amino acids) rapidly in both the insect vector and vertebrate host. Indeed, recent gene deletion studies suggest that mammal-infective stages are dependent on multiple carbon sourcesin vivo. The application of metabolomic approaches, outlined here, are likely to be important in defining aspects of central carbon metabolism that are essential at different stages of mammalian host infection.
UNIT ROOT TESTS WITH WAVELETS
Authors: Fan Yanqin , Gençay Ramazan
Published: February 2010

This paper develops a wavelet (spectral) approach to testing the presence of a unit root in a stochastic process. The wavelet approach is appealing, since it is based directly on the different behavior of the spectra of a unit root process and that of a short memory stationary process. By decomposing the variance (energy) of the underlying process into the variance of its low frequency components and that of its high frequency components via the discrete wavelet transformation (DWT), we design unit root tests against near unit root alternatives. Since DWT is an energy preserving transformation and able to disbalance energy across high and low frequency components of a series, it is possible to isolate the most persistent component of a series in a small number of scaling coefficients. We demonstrate the size and power properties of our tests through Monte Carlo simulations.
ON TAIL INDEX ESTIMATION FOR DEPENDENT, HETEROGENEOUS DATA
Authors: Hill Jonathan B.
Published: February 2010

In this paper we analyze the asymptotic properties of the popular distribution tail index estimator by Hill (1975) for dependent, heterogeneous processes. We develop new extremal dependence measures that characterize a massive array of linear, nonlinear, and conditional volatility processes with long or short memory. We prove that the Hill estimator is weakly and uniformly weakly consistent for processes with extremes that form mixingale sequences and asymptotically normal for processes with extremes that are near epoch dependent (NED) on some arbitrary mixing functional. The extremal persistence assumptions in this paper are known to hold for mixing,Lp-NED, and some non-Lp-NED processes, including ARFIMA, FIGARCH, explosive GARCH, nonlinear ARMA-GARCH, and bilinear processes, and nonlinear distributed lags like random coefficient and regime-switching autoregressions.

Finally, we deliver a simple nonparametric estimator of the asymptotic variance of the Hill estimator and prove consistency for processes with NED extremes.
Pregnancy-associated listeriosis
Authors: JACKSON K. A. , IWAMOTO M. , SWERDLOW D.
Published: February 2010

Infection by Listeria monocytogenes in pregnant women may result in fetal loss or invasive disease in the newborn. We examined listeriosis cases reported through the U.S. Listeria Initiative during 2004–2007. Cases were classified as pregnancy-associated if illness occurred in a pregnant woman or an infant aged <28 days. Of 758 reported Listeria cases, 128 (16·9%) were pregnancy-associated. Maternal infection resulted in four neonatal deaths and 26 (20·3%) fetal losses. Invasive illnesses in newborns (n=85) were meningitis (32·9%) and sepsis (36·5%). Pregnant women with Listeria were more likely to report Hispanic ethnicity (52·8% vs. 25·6%, respectively; OR 3·3 95% CI 2·2–4·8) than mothers giving live birth in the USA during 2005 and were more likely to report consumption of Mexican-style cheese (OR 2·6, 95% CI 1·6–4·2) than were non-pregnant patients with Listeria infection. Pregnant woman comprised a considerable proportion of reported listeriosis cases. Further declines in pregnancy-associated listeriosis will require education about avoiding high-risk foods, and continued regulatory and industry efforts to decrease Listeria in foods.
Modelling seasonality and viral mutation to predict the course of an influenza pandemic
Authors: SHI P. , KESKINOCAK P. , SWANN J. L. , LEE B. Y.
Published: February 2010

As the 2009 H1N1 influenza pandemic (H1N1) has shown, public health decision-makers may have to predict the subsequent course and severity of a pandemic. We developed an agent-based simulation model and used data from the state of Georgia to explore the influence of viral mutation and seasonal effects on the course of an influenza pandemic. We showed that when a pandemic begins in April certain conditions can lead to a second wave in autumn (e.g. the degree of seasonality exceeding 0·30, or the daily rate of immunity loss exceeding 1% per day). Moreover, certain combinations of seasonality and mutation variables reproduced three-wave epidemic curves. Our results may offer insights to public health officials on how to predict the subsequent course of an epidemic or pandemic based on early and emerging viral and epidemic characteristics and what data may be important to gather.
The set of habitable planets and astrobiological regulation mechanisms
Authors: Vukotić Branislav
Published: February 2010

The number of habitable planets in the Milky Way and its temporal variation are major unknowns in the nascent fields of astrobiology and Search for ExtraTerrestrial Intelligence studies. All numerical models developed thus far have suffered from large uncertainties in the input data, in addition to our lack of understanding of the processes of astrobiological dynamics. Here, we argue that at least the input data can now be specified with more confidence, and use a simple Monte Carlo model of the Galactic Habitable Zone (GHZ) as a flexible platform for their elucidation. Previous papers have described some of the major results of this class of models; in this paper we present its mechanics and input parameters, notably the number of the habitable planets in the GHZ and their temporal distribution, based on the results of Lineweaver et al. (Lineweaver, C.H., Fenner, Y. & Gibson, B.K. (2004). Science303, 59–62.) Regulation mechanisms (such as gamma-ray bursts or supernovae) and their temporal evolution, assumed to be main agents responsible for large-scale correlation effects, are modelled as type α (which can sterilize part of or the entire GHZ) and type β (which are of local importance) events with decreasing mean temporal frequency over the cosmological timescale. The considered global risk function implies as an upper limit that about one out of a hundred habitable sites will achieve high astrobiological complexity. The preliminary results of numerical modelling presented here and elsewhere imply that the lack of a sudden change from an essentially dead Galaxy to a Galaxy filled with complex life – the astrobiological phase transition – in our past (a version of Fermi's paradox) may be understood as a consequence of global astrobiological disequilibrium, strongly indicating such a transitional epoch in our future.
Work-Related Negative Experience
Authors: Martín Antonio Duro
Published: February 2010

This cross-sectional study examines the relationship between poor employee well-being (PEWB) and work-related mental ill-health and substance consumption (MIH). It is proposed as a unification model that links both work-related negative consequences on the basis of the experiences of threat, loss, and frustration at work. PEWB contains the following elements: emotional discomfort, bodily uneasiness, organizational distance, task impairment, and dragging workday; and MIH includes work-related anxiety, depression, irritability, cigarette smoking, alcohol and drug consumption, and physical illness. Six hundred ninety-seven participants, working in a wide range of jobs and occupations, completed the survey. Results indicated that PEWB and MIH are significantly associated, after controlling for demographic and personal factors. Sense sharing between PEWB-MIH and PEWB element combination explained the relationships between both constructs. These findings could be helpful for organizations interested in preserving and improving worker mental health.
Terror Management in a Predominantly Muslim Country
Authors: Kökdemir Doğan , Yeniçeri Zuhal
Published: February 2010

The mortality salience hypothesis of terror management theory was tested in a predominantly Muslim country. In Study 1a, private university students primed with thoughts of death reported more negative evaluations of a paragraph arguing state universities’ superiority to private ones, compared to a control condition in which “death” was replaced by “an important exam.” Study 1b conceptually replicated this finding at a state university. Study 2 found that MS participants wanted their home country to have stronger relations with Turkmenistan and weaker relations with England and Greece. Results were discussed with reference to university and national identity, and implications for future research were noted.
Satisfied and Dissatisfied Couples
Authors: Bertoni Anna , Bodenmann Guy
Published: February 2010

The purpose of the present study was to analyze marital functioning of satisfied couples and dissatisfied couples by comparing satisfied couples (85 couples), dissatisfied couples (55 couples), and dissatisfied couples in therapy (86 couples). The sample was composed of totally 226 married couples. Measures addressed topics such as positive and negative dimensions of marital functioning, conflict styles (compromise, violence, avoidance, and offence), and the quality of the relationship with family of origin. Results indicated that in comparison to dissatisfied couples, satisfied couples have more positive and less negative dimensions, a higher ratio between positivity and negativity, more appropriate conflict styles (more compromise and less violence, avoidance, and offence), as well as a better relationship with their family of origin. Satisfied couples significantly showed the highest levels of positive dimensions, while couples in therapy reported the highest levels of negative dimensions. Dissatisfied couples were in-between.
Morphologic dating of fault scarps using airborne laser swath mapping (ALSM) data
Authors: Hilley G. E. , DeLong S. , Prentice C. , Blisniuk K. , Arrowsmith JR.
Published: February 2010

Models of fault scarp morphology have been previously used to infer the relative age of different fault scarps in a fault zone using labor‐intensive ground surveying. We present a method for automatically extracting scarp morphologic ages within high‐resolution digital topography. Scarp degradation is modeled as a diffusive mass transport process in the across‐scarp direction. The second derivative of the modeled degraded fault scarp was normalized to yield the best‐fitting (in a least‐squared sense) scarp height at each point, and the signal‐to‐noise ratio identified those areas containing scarp‐like topography. We applied this method to three areas along the San Andreas Fault and found correspondence between the mapped geometry of the fault and that extracted by our analysis. This suggests that the spatial distribution of scarp ages may be revealed by such an analysis, allowing the recent temporal development of a fault zone to be imaged along its length.
Production of lightning NOx and its vertical distribution calculated from three‐dimensional cloud‐scale chemical transport model simulations
Authors: Ott Lesley E. , Pickering Kenneth E. , Stenchikov Georgiy L. , Allen Dale J. , DeCaria Alex J. , Ridley Brian , Lin Ruei‐Fong , Lang Stephen , Tao Wei‐Kuo
Published: February 2010

A three‐dimensional (3‐D) cloud‐scale chemical transport model that includes a parameterized source of lightning NOx on the basis of observed flash rates has been used to simulate six midlatitude and subtropical thunderstorms observed during four field projects. Production per intracloud (PIC) and cloud‐to‐ground (PCG) flash is estimated by assuming various values of PIC and PCG for each storm and determining which production scenario yields NOx mixing ratios that compare most favorably with in‐cloud aircraft observations. We obtain a mean PCG value of 500 moles NO (7 kg N) per flash. The results of this analysis also suggest that on average, PIC may be nearly equal to PCG, which is contrary to the common assumption that intracloud flashes are significantly less productive of NO than are cloud‐to‐ground flashes. This study also presents vertical profiles of the mass of lightning NOx after convection based on 3‐D cloud‐scale model simulations. The results suggest that following convection, a large percentage of lightning NOx remains in the middle and upper troposphere where it originated, while only a small percentage is found near the surface. The results of this work differ from profiles calculated from 2‐D cloud‐scale model simulations with a simpler lightning parameterization that were peaked near the surface and in the upper troposphere (referred to as a “C‐shaped” profile). The new model results (a backward C‐shaped profile) suggest that chemical transport models that assume a C‐shaped vertical profile of lightning NOx mass may place too much mass near the surface and too little in the middle troposphere.
Soil pH, ecological stoichiometry, and allometric scaling in soil biota
Authors: Mulder Christian , Elser James
Published: February 2010

The factors regulating the structure of food webs are a central focus of community andecosystem ecology, as trophic interactions among species have important impacts onnutrient storage and cycling in many ecosystems. For soil invertebrates in grasslandecosystems in the Netherlands, the site-specific slopes of the faunal biomass to organism body mass relationships reflected basic biochemical and biogeochemical processes associated with soil acidity and soil C:N:P stoichiometry. That is, the higher the phosphorus availability in the soil, the higher, on average, the slope of the faunal biomass size spectrum (i.e., the higher the biomass of large-bodied invertebrates relative to the biomass of small invertebrates). While other factors may also be involved, these results are consistent with the growth rate hypothesis from biological stoichiometry that relates phosphorus demands to ribosomal RNA and protein production. Thus our data represent the first time that ecosystem phosphorus availability has been associated with allometry in soil food webs (supporting information available online). Our results have broad implications, as soil invertebrates of different size have different effects on soil processes.
Surface and finite size effect on fluctuations dynamics in nanoparticles with long-range order
Authors: Morozovska A. N. , Eliseev E. A.
Published: February 2010

The influence of surface and finite size on the dynamics of the order parameter fluctuations and critical phenomena in the three-dimensional (3D)-confined systems with long-range order was not considered theoretically. In this paper, we study the influence of surface and finite size on the dynamics of the order parameter fluctuations in the particles of arbitrary shape. We consider concrete examples of the spherical and cylindrical ferroic nanoparticles within Landau–Ginzburg–Devonshire phenomenological approach. Allowing for the strong surface energy contribution in micro and nanoparticles, the analytical expressions derived for the Ornstein–Zernike correlator of the long-range order parameter spatial-temporal fluctuations, dynamic generalized susceptibility, relaxation times, and correlation radii discrete spectra are different from those known for bulk systems. Obtained analytical expressions for the correlation function of the order parameter spatial-temporal fluctuations in micro and nanosized systems can be useful for the quantitative analysis of the dynamical structural factors determined from magnetic resonance diffraction and scattering spectra. Besides the practical importance of the correlation function for the analysis of the experimental data, derived expressions for the fluctuations strength determine the fundamental limits of phenomenological theories applicability for 3D-confined systems.
Effects of rf-bias power on plasma parameters in a low gas pressure inductively coupled plasma
Authors: Lee Hyo-Chang , Lee Min-Hyong , Chung Chin-Wook
Published: February 2010

Remarkable changes of the electron temperature and the plasma density by increasing bias power were observed in low gas pressure inductively coupled plasma (ICP) by the measurement of electron energy distribution function (EEDF). As the bias power increases, the electron temperature increased with accompanying the evolution of the EEDF from a bi-Maxwellian to a Maxwellian distribution. However, a different trend of the plasma density was observed with a dependence on the ICP powers. When the ICP power was relatively small or the discharge is in capacitive mode (E mode), the plasma density increased considerably with the bias power, while decrease of the plasma density was observed when the discharge is in inductive mode (H mode). The change of the plasma density can be explained by the balance between total power absorption and power dissipation.
Vascular structures for volumetric cooling and mechanical strength
Authors: Wang K.-M. , Lorente S. , Bejan A.
Published: February 2010

When solid material is removed in order to create flow channels in a load carrying structure, the strength of the structure decreases. On the other hand, a structure with channels is lighter and easier to transport as part of a vehicle. Here, we show that this trade off can be used for benefit, to design a vascular mechanical structure. When the total amount of solid is fixed and the sizes, shapes, and positions of the channels can vary, it is possible to morph the flow architecture such that it endows the mechanical structure with maximum strength. The result is a multifunctional structure that offers not only mechanical strength but also new capabilities necessary for volumetric functionalities such as self-healing and self-cooling. We illustrate the generation of such designs for strength and fluid flow for several classes of vasculatures: parallel channels, trees with one, two, and three bifurcation levels. The flow regime in every channel is laminar and fully developed. In each case, we found that it is possible to select not only the channel dimensions but also their positions such that the entire structure offers more strength and less flow resistance when the total volume (or weight) and the total channel volume are fixed. We show that the minimized peak stress is smaller when the channel volume (ϕ) is smaller and the vasculature is more complex, i.e., with more levels of bifurcation. Diminishing returns are reached in both directions, decreasing ϕ and increasing complexity. For example, when ϕ=0.02 the minimized peak stress of a design with one bifurcation level is only 0.2% greater than the peak stress in the optimized vascular design with two levels of bifurcation.
Improvement of reproducible resistance switching in polycrystalline tungsten oxide films by in situ oxygen annealing
Authors: Shang D. S. , Shi L. , Sun J. R. , Shen B. G. , Zhuge F. , Li R. W. , Zhao Y. G.
Published: February 2010

The electric-field-induced resistance switching in polycrystalline tungsten oxide films was investigated. Compared with the as-deposited film, the film annealed in an oxygen atmosphere shows a more stable switching behavior, a higher low-to-high resistance ratio, and a better endurance and retention. Based on the x-ray photoemission spectroscopy analysis, the resistance switching was attributed to the change in the interfacial barrier potential, due to the electron trapping/detrapping in the surface states, and the switching improvement was attributed to the decrease in the surface density of states. The present work suggests a possible approach controlling the resistance switching property by surface modification.
Stabilization of pressure-driven magnetohydrodynamic modes by separatrix in dipole plasma confinement
Authors: Furukawa M. , Hayashi H. , Yoshida Z.
Published: February 2010

The eigenvalue problem is solved for the short-wavelength pressure-driven magnetohydrodynamic modes in configuration with closed magnetic field lines in the poloidal direction. Here we show that the magnetic separatrix (which determines the boundary of the confinement region) provides a substantial stabilizing effect by which the total volume inside the separatrix becomes stable even for very high beta values. The plasma inertia and compressibility are properly formulated to give the correct growth rate of the mode.
Elucidation of microstructures produced in Ni51Fe22Ga27 ferromagnetic shape memory alloy
Authors: Murakami Y. , Yano T. , Shindo D. , Kainuma R. , Oikawa K. , Ishida K.
Published: February 2010

Both the magnetic and crystallographic microstructures in the ferromagnetic shape memory alloy Ni51Fe22Ga27 were extensively studied by electron holography, electron diffraction, dark-field image observations, and the phenomenological crystallographic theory of martensitic transformations. This study elucidated anomalies that were observed in the magnetic flux pattern before the onset of the martensitic transformation. Furthermore, the observations clarified the relationship between the magnetization vectors and the shape strain directions in the martensite variants that formed a self-accommodation group.
A nondestructive analysis of the B diffusion in Ta–CoFeB–MgO–CoFeB–Ta magnetic tunnel junctions by hard x-ray photoemission
Authors: Kozina Xeniya , Ouardi Siham , Balke Benjamin , Stryganyuk Gregory , Fecher Gerhard H. , Felser Claudia , Ikeda Shoji , Ohno Hideo , Ikenaga Eiji
Published: February 2010

This work reports on hard x-ray photoelectron spectroscopy (HAXPES) of CoFeB based tunnel junctions. Aim is to explain the role of the boron diffusion for the observed improvement of the tunneling magnetoresistance ratio with increasing annealing temperature. The high bulk sensitivity of HAXPES was used as a nondestructive technique to analyze CoFeB–MgO–CoFeB magnetic tunnel junctions. The investigated samples were processed at different annealing temperatures from 523 to 923 K. Hard x-ray core level spectroscopy reveals an enforced diffusion of boron from the CoFeB into the adjacent Ta layer with increasing annealing temperature. The dependence of the tunneling magnetoresistance on the annealing temperature is explained by the combined effects of an improved crystalline structure together with a change in the spin polarization at the Fermi energy caused by the removal of boron from the CoFeB layer and Ta diffusion at high annealing temperature.
Note: An ultranarrow bandpass filter system for single-photon experiments in quantum optics
Authors: Höckel David , Martin Eugen , Benson Oliver
Published: February 2010

We describe a combined ultranarrow bandpass filtering setup for single-photon experiments in quantum optics. The filter is particularly suitable for single-photon electromagnetically induced transparency (EIT) experiments, but can also be used in several similar applications. A multipass planar Fabry–Pérot etalon together with polarization filters and spatial filtering allows 114 dB pump beam suppression, while the signal beam is attenuated by just 4 dB, although both wavelengths are only separated by 0.025 nm (9.2 GHz). The multipass etalon alone accounts for 46 dB suppression while it has a peak transmission of 65%. We demonstrate EIT experiments in Cs vapor at room temperature with probe power in the femtowatt regime using this filter.
Vortex liquid-glass transition up to 60 T in nanoengineered coated conductors grown by metal organic deposition
Authors: Miura M. , Baily S. A. , Maiorov B. , Civale L. , Willis J. O. , Marken K. , Izumi T. , Tanabe K. , Shiohara Y.
Published: February 2010

Higher irreversibility fields (Hirr) increase the upper bound for applications of superconductors and could expand market penetration. We present the studies in pulsed field (up to 65 T) of superconducting films on flexible metal substrates. We investigate the effect of disorder on Hirr at different field orientations for YBa2Cu3Oy and BaZrO3-nanoparticle-dispersed Y0.77Gd0.33Ba2Cu3Oy (YGdBCO+BZO). We find that Hirr is higher for YGdBCO+BZO along the c-axis and at intermediate orientations. The vortex melting transition is investigated using the resistive transition’s critical exponent. The behavior can be explained by the mixed pinning landscape from randomly distributed BZO nanoparticles and c-axis correlated disorder.
Decoherence and quantum-classical dynamics in a dissipative bath
Authors: Rank J. P. , Kapral Raymond
Published: February 2010

The dynamics of a mixed quantum-classical system, in which the classical subsystem interacts with a dissipative bath, is investigated. This description of the dynamics will be appropriate if the details of the bath dynamics are unimportant but its presence plays an important role in the dissipation of energy to the environment. In this dynamical description, which can be simulated employing an ensemble of stochastic surface-hopping trajectories, the strength of the dissipation is controlled by a friction coefficient. We show that if decoherence, whose effects are controlled by the bath friction, is sufficiently rapid, the equation of motion can be reduced to a master equation. Thus, decoherence and the validity of master equation models may be explored as a function of bath friction. We use this framework to study the mechanism of decoherence in a simple model nonadiabatic chemical reaction.
Long-lasting molecular alignment: Fact or fiction?
Authors: Ortigoso Juan , Rodríguez Mirta , Santos Julio , Karpati Attila , Szalay Viktor
Published: February 2010

It has been suggested that appropriate periodic sequences of laser pulses can maintain molecular alignment for arbitrarily long times [J. Ortigoso, Phys. Rev. Lett. 93, 073001 (2004)]. These aligned states are found among the cyclic eigenstates of truncated matrix representations of the one-period time propagator U(T,0). However, long time localization of periodic driven systems depends on the nature of the spectrum of their exact propagator; if it is continuous, eigenstates of finite-basis propagators cease to be cyclic, in the long time limit, under the exact time evolution. We show that, for very weak laser intensities, the evolution operator of the system has a point spectrum for most laser frequencies, but for the laser powers needed to create aligned wave packets it is unknown if U(T,0) has a point spectrum or a singular continuous spectrum. For this regime, we obtain error bounds on the exact time evolution of rotational wave packets that allow us to determine that truncated aligned cyclic states do not lose their alignment for millions of rotational periods when they evolve under the action of the exact time propagator.
Lasing characteristics at different band edges in GaN photonic crystal surface emitting lasers
Authors: Chen S. W. , Lu T. C. , Hou Y. J. , Liu T. C. , Kuo H. C. , Wang S. C.
Published: February 2010

We have investigated the lasing characteristics of GaN-based two-dimensional photonic crystal surface emitting lasers (PCSELs) with different PC lattice constants by using angled resolved spectroscopy. Due to the Bragg diffraction theory, normalized frequency of lasing wavelength of PCSELs can be exactly matched with three distinct band-edge frequencies (Γ1, K2, and M3) in the photonic band diagram. The three band-edge frequencies (Γ1, K2, and M3) have different emission angles corresponding to the normal direction of the sample (0°, 29°, and 59.5°).
Very high open-circuit voltage ultraviolet photovoltaic diode with its application in optical encoder field
Authors: Zhang Guang , Li Wenlian , Chu Bei , Yan Fei , Zhu Jianzhuo , Chen Yiren
Published: February 2010

We demonstrate a very high voltage based organic photovoltaic (PV) diode by stacking two ultraviolet (UV) sensitized organic PV diodes. It shows an open-circuit voltage (Voc) of 4.34 V under 365 nm UV irradiation with intensity of 2 mW/cm2. Due to the especially high Voc the PV diode device could be integrated in electronic logic device, as a result a high or a low potential states can be harvested directly under the UV irradiation or not, respectively. The difference between high and low potential states is great and the temporal response is fast, which make it an attractive and promising candidate in application of optical encoder.
Thyroid hormone exerts negative feedback on hypothalamic type 4 melanocortin receptor expression
Authors: Decherf Stéphanie , Seugnet Isabelle , Kouidhi Soumaya , Lopez-Juarez Alejandra , Clerget-Froidevaux Marie-Stéphanie , Demeneix Barbara A.
Published: February 2010

The type 4 melanocortin receptor MC4R, a key relay in leptin signaling, links central energy control to peripheral reserve status. MC4R activation in different brain areas reduces food intake and increases energy expenditure. Mice lacking
Mc4r
are obese.
Mc4r
is expressed by hypothalamic paraventricular Thyrotropin-releasing hormone (TRH) neurons and increases energy usage through activation of
Trh
and production of the thyroid hormone tri-iodothyronine (T
3
). These facts led us to test the hypothesis that energy homeostasis should require negative feedback by T
3
on
Mc4r
expression. Quantitative PCR and in situ hybridization showed hyperthyroidism reduces
Mc4r
mRNA levels in the paraventricular nucleus. Comparative
in silico
analysis of
Mc4r
regulatory regions revealed two evolutionarily conserved potential negative thyroid hormone-response elements (nTREs). In vivo ChIP assays on mouse hypothalamus demonstrated association of thyroid hormone receptors (TRs) with a region spanning one nTRE. Further, in vivo gene reporter assays revealed dose-dependent T
3
repression of transcription from the
Mc4r
promoter in mouse hypothalamus, in parallel with T
3
-dependent
Trh
repression. Mutagenesis of the nTREs in the
Mc4r
promoter demonstrated direct regulation by T
3
, consolidating the ChIP results. In vivo shRNA knockdown, TR over-expression approaches and use of mutant mice lacking specific TRs showed that both TRα and TRβ contribute to
Mc4r
regulation. T
3
repression of
Mc4r
transcription ensures that the energy-saving effects of T
3
feedback on
Trh
are not overridden by MC4R activation of
Trh.
Thus parallel repression by T
3
on hypothalamic
Mc4r
and
Trh
contributes to energy homeostasis.
Active multilayered capsules for in vivo bone formation
Authors: Facca S. , Cortez C. , Mendoza-Palomares C. , Messadeq N. , Dierich A. , Johnston A. P. R. , Mainard D. , Voegel J.-C. , Caruso F. , Benkirane-Jessel N.
Published: February 2010

Interest in the development of new sources of transplantable materials for the treatment of injury or disease has led to the convergence of tissue engineering with stem cell technology. Bone and joint disorders are expected to benefit from this new technology because of the low self-regenerating capacity of bone matrix secreting cells. Herein, the differentiation of stem cells to bone cells using active multilayered capsules is presented. The capsules are composed of poly-L-glutamic acid and poly-L-lysine with active growth factors embedded into the multilayered film. The bone induction from these active capsules incubated with embryonic stem cells was demonstrated in vitro. Herein, we report the unique demonstration of a multilayered capsule-based delivery system for inducing bone formation in vivo. This strategy is an alternative approach for in vivo bone formation. Strategies using simple chemistry to control complex biological processes would be particularly powerful, as they make production of therapeutic materials simpler and more easily controlled.
Cycles, phase synchronization, and entrainment in single-species phytoplankton populations
Authors: Massie Thomas M. , Blasius Bernd , Weithoff Guntram , Gaedke Ursula , Fussmann Gregor F.
Published: February 2010

Complex dynamics, such as population cycles, can arise when the individual members of a population become synchronized. However, it is an open question how readily and through which mechanisms synchronization-driven cycles can occur in unstructured microbial populations. In experimental chemostats we studied large populations (>10
9
cells) of unicellular phytoplankton that displayed regular, inducible and reproducible population oscillations. Measurements of cell size distributions revealed that progression through the mitotic cycle was synchronized with the population cycles. A mathematical model that accounts for both the cell cycle and population-level processes suggests that cycles occur because individual cells become synchronized by interacting with one another through their common nutrient pool. An external perturbation by direct manipulation of the nutrient availability resulted in phase resetting, unmasking intrinsic oscillations and producing a transient collective cycle as the individuals gradually drift apart. Our study indicates a strong connection between complex within-cell processes and population dynamics, where synchronized cell cycles of unicellular phytoplankton provide sufficient population structure to cause small-amplitude oscillations at the population level.
Innate sensitivity for self-propelled causal agency in newly hatched chicks
Authors: Mascalzoni Elena , Regolin Lucia , Vallortigara Giorgio
Published: February 2010

The idea that sensitivity to self-produced motion could lie at the foundations of the clear-cut divide that the brain operates between the two basic domains of inanimate and animate objects dates back to Aristotle. Sensitivity to self-propelled objects is apparent in human infants from around the fifth month of age, which leaves undetermined whether it is acquired by experience with animate objects or whether it is innately predisposed in the brain. Here, we report that newly hatched, visually naïve domestic chicks presented with objects exhibiting motion either self-produced or caused by physical contact prefer to associate with self-propelled objects. This finding supports the idea of an evolutionarily ancient, predisposed neural mechanism in the vertebrate brain for the detection of animacy.
Spatiotemporal compartmentalization of key physiological processes during muscle precursor differentiation
Authors: Özbudak Ertuğrul M , Tassy Olivier , Pourquié Olivier
Published: February 2010

The development of multicellular organisms is controlled by transcriptional networks. Understanding the role of these networks requires a full understanding of transcriptome regulation during embryogenesis. Several microarray studies have characterized the temporal evolution of the transcriptome during development in different organisms [Wang QT, et al. (2004)
Dev Cell
6:133–144; Furlong EE, Andersen EC, Null B, White KP, Scott MP (2001)
Science
293:1629–1633; Mitiku N, Baker JC (2007)
Dev Cell
13:897–907]. In all cases, however, experiments were performed on whole embryos, thus averaging gene expression among many different tissues. Here, we took advantage of the local synchrony of the differentiation process in the paraxial mesoderm. This approach provides a unique opportunity to study the systems-level properties of muscle differentiation. Using high-resolution, spatiotemporal profiling of the early stages of muscle development in the zebrafish embryo, we identified a major reorganization of the transcriptome taking place in the presomitic mesoderm. We further show that the differentiation process is associated with a striking modular compartmentalization of the transcription of essential components of cellular physiological programs. Particularly, we identify a tight segregation of cell cycle/DNA metabolic processes and translation/oxidative metabolism at the tissue level, highly reminiscent of the yeast metabolic cycle. These results should expand more investigations into the developmental control of metabolism.
Selective loss of polymorphic mating types is associated with rapid phenotypic evolution during morphic speciation
Authors: Corl Ammon , Davis Alison R. , Kuchta Shawn R. , Sinervo Barry
Published: February 2010

Polymorphism may play an important role in speciation because new species could originate from the distinctive morphs observed in polymorphic populations. However, much remains to be understood about the process by which morphs found new species. To detail the steps of this mode of speciation, we studied the geographic variation and evolutionary history of a throat color polymorphism that distinguishes the “rock-paper-scissors” mating strategies of the side-blotched lizard,
Uta stansburiana
. We found that the polymorphism is geographically widespread and has been maintained for millions of years. However, there are many populations with reduced numbers of throat color morphs. Phylogenetic reconstruction showed that the polymorphism is ancestral, but it has been independently lost eight times, often giving rise to morphologically distinct subspecies/species. Changes to the polymorphism likely involved selection because the allele for one particular male strategy, the “sneaker” morph, has been lost in all cases. Polymorphism loss was associated with accelerated evolution of male size, female size, and sexual dimorphism, which suggests that polymorphism loss can promote rapid divergence among populations and aid species formation.
Yeast Tdp1 regulates the fidelity of nonhomologous end joining
Authors: Bahmed Karim , Nitiss Karin C. , Nitiss John L.
Published: February 2010

Tyrosyl-DNA-phosphodiesterase 1 (Tdp1) can disjoin peptides covalently bound to DNA. We assessed the role of Tdp1 in nonhomologous end joining (NHEJ) and found that linear DNA molecules with 5′ extensions showed a high frequency of misrepair in Δ
tdp
1 cells. The joining errors in Δ
tdp
1 cells were predominantly 2-4 nucleotide insertions. Ends with 3′ extensions or blunt ends did not show enhanced frequencies of errors, although Δ
tdp
1 cells repaired blunt DNA ends with greater efficiency than WT cells. We found that insertions required Ku80 and DNA ligase IV, as well as polymerase IV. Our results show that yeast Tdp1 is a component of the NHEJ pathway. We suggest that Tdp1p 3′ nucleosidase activity regulates the processing of DNA ends by generating a 3′ phosphate, thereby restricting the ability of polymerases and other enzymes from acting at DNA ends. In support of this model, we found that overexpression of Tpp1, a yeast DNA 3′ phosphatase, also leads to a higher frequency of insertions, suggesting that the generation of a 3′ phosphate is a key step in Tdp1-mediated error prevention during NHEJ.
Macrophage Wnt7b is critical for kidney repair and regeneration
Authors: Lin Shuei-Liong , Li Bing , Rao Sujata , Yeo Eun-Jin , Hudson Thomas E. , Nowlin Brian T. , Pei Huaying , Chen Lijun , Zheng Jie J. , Carroll Thomas J. , Pollard Jeffrey W. , McMahon Andrew P. , Lang Richard A. , Duffield Jeremy S.
Published: February 2010

Macrophages are required for tissue homeostasis through their role in regulation of the immune response and the resolution of injury. Here we show, using the kidney as a model, that the Wnt pathway ligand Wnt7b is produced by macrophages to stimulate repair and regeneration. When macrophages are inducibly ablated from the injured kidney, the canonical Wnt pathway response in kidney epithelial cells is reduced. Furthermore, when
Wnt7b
is somatically deleted in macrophages, repair of injury is greatly diminished. Finally, injection of the Wnt pathway regulator Dkk2 enhances the repair process and suggests a therapeutic option. Because Wnt7b is known to stimulate epithelial responses during kidney development, these findings suggest that macrophages are able to rapidly invade an injured tissue and reestablish a developmental program that is beneficial for repair and regeneration.
Observation of halogen species in the Amundsen Gulf, Arctic, by active long-path differential optical absorption spectroscopy
Authors: Pöhler Denis , Vogel Leif , Frieß Udo , Platt Ulrich
Published: February 2010

In the polar tropospheric boundary layer, reactive halogen species (RHS) are responsible for ozone depletion as well as the oxidation of elemental mercury and dimethyl sulphide. After polar sunrise, air masses enriched in reactive bromine cover areas of several million square kilometers. Still, the source and release mechanisms of halogens are not completely understood. We report measurements of halogen oxides performed in the Amundsen Gulf, Arctic, during spring 2008. Active long-path differential optical absorption spectroscopy (LP-DOAS) measurements were set up offshore, several kilometers from the coast, directly on the sea ice, which was never done before. High bromine oxide concentrations were detected frequently during sunlight hours with a characteristic daily cycle showing morning and evening maxima and a minimum at noon. The, so far, highest observed average mixing ratio in the polar boundary layer of 41 pmol/mol (equal to pptv) was detected. Only short sea ice contact is required to release high amounts of bromine. An observed linear decrease of maximum bromine oxide levels with ambient temperature during sunlight, between -24 °C and -15 °C, provides indications on the conditions required for the emission of RHS. In addition, the data indicate the presence of reactive chlorine in the Arctic boundary layer. In contrast to Antarctica, iodine oxide was not detected above a detection limit of 0.3 pmol/mol.
Pathway of ATP utilization and duplex rRNA unwinding by the DEAD-box helicase, DbpA
Authors: Henn Arnon , Cao Wenxiang , Licciardello Nicholas , Heitkamp Sara E. , Hackney David D. , De La Cruz Enrique M.
Published: February 2010

DEAD-box RNA helicase proteins use the energy of ATP hydrolysis to drive the unwinding of duplex RNA. However, the mechanism that couples ATP utilization to duplex RNA unwinding is unknown. We measured ATP utilization and duplex RNA unwinding by DbpA, a non-processive bacterial DEAD-box RNA helicase specifically activated by the peptidyl transferase center (PTC) of 23S rRNA. Consumption of a single ATP molecule is sufficient to unwind and displace an 8 base pair rRNA strand annealed to a 32 base pair PTC-RNA “mother strand” fragment. Strand displacement occurs after ATP binding and hydrolysis but before P

i

product release. P

i

release weakens binding to rRNA, thereby facilitating the release of the unwound rRNA mother strand and the recycling of DbpA for additional rounds of unwinding. This work explains how ATPase activity of DEAD-box helicases is linked to RNA unwinding.
Cortical activity during motor execution, motor imagery, and imagery-based online feedback
Authors: Miller Kai J. , Schalk Gerwin , Fetz Eberhard E. , den Nijs Marcel , Ojemann Jeffrey G. , Rao Rajesh P. N.
Published: February 2010

Imagery of motor movement plays an important role in learning of complex motor skills, from learning to serve in tennis to perfecting a pirouette in ballet. What and where are the neural substrates that underlie motor imagery-based learning? We measured electrocorticographic cortical surface potentials in eight human subjects during overt action and kinesthetic imagery of the same movement, focusing on power in “high frequency” (76–100 Hz) and “low frequency” (8–32 Hz) ranges. We quantitatively establish that the spatial distribution of local neuronal population activity during motor imagery mimics the spatial distribution of activity during actual motor movement. By comparing responses to electrocortical stimulation with imagery-induced cortical surface activity, we demonstrate the role of primary motor areas in movement imagery. The magnitude of imagery-induced cortical activity change was ∼25% of that associated with actual movement. However, when subjects learned to use this imagery to control a computer cursor in a simple feedback task, the imagery-induced activity change was significantly augmented, even exceeding that of overt movement.