bluuebunny/crossref_metadata_2025 huggingface dataset:
Structure–property relationships in glass‐reinforced polyamide, Part 3: Effects of hydrolysis ageing on the dimensional stability and performance of short glass–fiber‐reinforced polyamide 66
Authors: Thomason J.L.
Published: May 2007

We present results on an in‐depth study of the effects of hydrolysis testing on the mechanical performance, weight change, and dimensional stability of injection molded glass–fiber‐reinforced polyamide 66 (PA66) based on two chopped fiber products with different sizing formulations. Composite and resin samples have been characterized both dry as molded and after conditioning at either 120 or 150°C for a range of times up to 1,000 h. The results reveal that hydrothermal ageing in water–glycol mixtures results in significant changes in the mechanical performance, weight, and dimensions of these materials. The negative effects of conditioning could be mitigated to some degree by the appropriate choice of the glass–fiber sizing; however, the sizing effect diminished with increasing conditioning time. All materials showed a weight increase due to conditioning at 120°C that was typical of a single Fickian diffusion process and there was clear evidence of multiple processes involved when conditioning at 150°C. It was not apparent that the glass–fiber sizing affected the dimensional stability of the composites. We show that there is a strong correlation between the swelling of these samples and the level of fluid adsorption. Although the PA66 resin showed reasonably homogeneous swelling, the composites exhibited different levels of swelling depending on direction. These effects were well in line with the known effects of fibers on restriction of the matrix deformation (mechanical, thermal, or moisture swelling) in the fiber direction. These differences correlate well with the average fiber orientation with respect to the various direction axes. Composite tensile strength and unnotched impact resistance appeared to scale inversely with the level of swelling of the material. POLYM. COMPOS. 28:344–354, 2007. © 2007 Society of Plastics Engineers.
Stress and prions: Lessons from the yeast model
Authors: Chernoff Yury O.
Published: May 2007

Yeast self‐perpetuating amyloids (prions) provide a convenient model for studying the cellular control of highly ordered aggregates involved in mammalian protein assembly disorders. The very ability of an amyloid to propagate a prion state in yeast is determined by its interactions with the stress‐inducible chaperone Hsp104. Prion formation and propagation are also influenced by other stress‐related chaperones (Hsp70 and Hsp40), and by alterations of the protein trafficking and degradation networks. Some stress conditions induce prion formation or loss. It is proposed that prions arise as byproducts of the reversible assembly of highly ordered complexes, protecting certain proteins during unfavorable conditions.
Human immortalized chondrocytes carrying heterozygous FGFR3 mutations: An in vitro model to study chondrodysplasias
Authors: Benoist-Lasselin Catherine , Gibbs Linda , Heuertz Solange , Odent Thierry , Munnich Arnold , Legeai-Mallet Laurence
Published: May 2007

Achondroplasia and thanatophoric dysplasia are human chondrodysplasias caused by mutations in the fibroblast growth factor receptor 3 (FGFR3) gene. We have developed an immortalized human chondrocyte culture model to study the regulation of chondrocyte functions. One control and eight mutant chondrocytic lines expressing different FGFR3 heterozygous mutations were obtained. FGFR3 signaling pathways were modified in the mutant lines as revealed by the constitutive activation of the STAT pathway and an increased level of P21WAF1/CIP1 protein. This model will be useful for the study of FGFR3 function in cartilage studies and future therapeutic approaches in chondrodysplasias.
THE REFORM OF WORKING LIFE IN BRITAIN, 1963–1971
Authors: WHITING RICHARD
Published: May 2007

In the 1960s and 1970s both Conservative and Labour governments passed novel laws dealing with the rights of individuals at work. Overshadowed by conflicts over collective labour law, the political significance of this legislation has remained unexplored. This article suggests that the legislation struck a balance between recognizing the complexity of work in a modern society, and preserving managerial authority. It also argues that the reforms served a Conservative agenda in rooting an individual interest in work in a legal process. This was part of a pivotal challenge to the system of voluntary collective bargaining that had traditionally benefited the labour movement.
Morphological Aspects of the Traumatic Chronic Subdural Hematoma Capsule: SEM Studies
Authors: Moskała Marek , Gościński Igor , Kałuża Józef , Polak Jarosław , Krupa Mariusz , Adamek Dariusz , Pityński Kazimierz , Miodoński Adam J.
Published: May 2007

The morphology of the outer and inner membranes of traumatic chronic subdural hematomas (CSDHs) surgically removed from eight patients was investigated by scanning electron microscopy (SEM). Hematomas were divided into three groups based on time that had passed from the initiation of trauma to surgery. Structure of the CSDHs showed gradual morphological changes of the developing hematoma capsule. They initially included angiogenic and aseptic inflammatory reactions followed by progressive involvement of fibroblasts—proliferating and producing collagen fibrils. Numerous capillaries suggesting formation of new blood vessels were observed mainly in young hematomas removed between 15 and 21 days after trauma. In “older” hematomas (40 days after trauma), more numerous capillaries and thin-walled sinusoids were accompanied by patent, larger diameter blood vessels. Within the fibrotic outer membrane of the “oldest” hematoma capsules (60 or more days after trauma), especially in the area over the hematoma cavity, blood vessels were frequently occluded by clots. The results suggest dynamic changes in cellular and vascular organization of traumatic CSDH capsules paralleling the progression in hematoma age.
Stochastic optimization of multireservoir operation: The optimal reservoir trajectory approach
Authors: Turgeon André
Published: May 2007

The paper presents a new method for determining the optimal operating policy of a power system of several reservoirs in series. The method, called optimal reservoir trajectory (ORT), is based on the following fact: Raising the level of a reservoir feeding a power plant is profitable as long as the gain due to the higher head is greater than the loss due to the additional spillage. There consequently exists a reservoir level at time t at which the expected energy generation is maximized. The task of ORT is to find this level and use it to operate the reservoir. The problem is more complicated for several reservoirs in series since the optimal level of each reservoir is a function of the levels of all the other reservoirs. The paper shows how to solve this problem and presents the results obtained for systems of two, three, and seven reservoirs. The results for the systems of two and three reservoirs are compared with those obtained with stochastic dynamic programming.
Near‐surface permafrost degradation: How severe during the 21st century?
Authors: Delisle G.
Published: May 2007

A previously presented model on nearly complete near‐surface permafrost degradation in the Arctic during the 21st century is critically reviewed. An alternative model with a more complete mathematical formulation of the physical processes acting in permafrost terrain is presented, which suggests that permafrost will mostly prevail in this century in areas north of 70°N. Furthermore, permafrost will survive at depth in most areas between 60° to 70°N. Based on paleoclimatic data and in consequence of this study, it is suggested that scenarios calling for massive release of methane in the near future from degrading permafrost are questionable.
Tropical oceanic cloudiness and the incidence of precipitation: Early results from CloudSat
Authors: Haynes John M. , Stephens Graeme L.
Published: May 2007

Results of analysis of CloudSat radar data collected during the first three months of operation are described. It is shown that the global tropical oceans (30N–30S) predominantly favor clouds with tops in two layers centered at about 2 and 12 km. Precipitating clouds occur primarily in three modes, a shallow mode that is the most frequent type, as well as a middle and deep mode. Regional features are also discussed. The Indian and western Pacific Oceans exhibit more predominantly high clouds and deeper precipitation features than the eastern Pacific and Atlantic. The occurrence of a mid‐level mode of cloudiness and precipitation is shown to vary regionally, being particularly significant in the western Pacific. For all regions examined, precipitating clouds are observed to be deeper than non‐precipitating clouds. Over the global tropical oceans, 18% of the clouds detected by CloudSat produce precipitation.
Microstructures and magnetic alignment of L10 FePt nanoparticles
Authors: Kang Shishou , Shi Shifan , Jia Zhiyong , Thompson G. B. , Nikles David E. , Harrell J. W. , Li Daren , Poudyal Narayan , Nandwana Vikas , Liu J. Ping
Published: May 2007

Chemically ordered FePt nanoparticles were obtained by high temperature annealing a mixture of FePt particles with NaCl. After the NaCl was removed with de-ionized water, the transformed FePt nanoparticles were redispersed in cyclohexanone. X-ray diffraction patterns clearly show the L10 phase. Scherrer analysis indicates that the average particle size is about 8nm, which is close to the transmission electron microscopy (TEM) statistical results. The coercivity ranges from 16kOe to more than 34kOe from room temperature down to 10K. High resolution TEM images reveal that most of the FePt particles were fully transformed into the L10 phase, except for a small fraction of particles which were partially chemically ordered. Nano-energy dispersive spectroscopy measurements on the individual particles show that the composition of the fully transformed particles is close to 50∕50, while the composition of the partially transformed particles is far from equiatomic. TEM images and electron diffraction patterns indicate c-axis alignment for a monolayer of L10 FePt particles formed by drying a dilute dispersion on copper grids under a magnetic field. For thick samples dried under a magnetic field, the degree of easy axis alignment is not as high as predicted due to strong interactions between particles.
Effect of a Ta-Si-N diffusion barrier on the texture formation in thin Cu films
Authors: Hübner R.
Published: May 2007

Analyzing pole figures obtained by x-ray diffraction experiments, quantitative texture analyses are carried out on 50 nm thick Cu films sputter-deposited on oxidized Si substrates and on Ta-Si-N diffusion barrier films of various compositions. To explain the observed Cu texture formation during layer deposition, a model of two-dimensional grain growth in thin films is applied. In the case of silicon oxide substrates, a ⟨111⟩ Cu fiber texture component resulting from the minimization of the surface and interface energy is observed, in addition to a ⟨100⟩ component resulting from the minimization of the strain energy. For Cu films deposited onto Ta-Si-N diffusion barriers, preferred growth occurs only for ⟨111⟩-oriented Cu grains and their twins. The volume fractions of both components decrease with increasing N content of the diffusion barrier. Annealing of the Cu films at Tan=600 °C results in a strengthening and a sharpening of the ⟨111⟩ component. Hence, both the chemical composition of the underlayer as well as a postdeposition anneal are observed to have a significant impact on the texture of thin Cu films.
Energy-based analysis of frequency entrainment described by van der Pol and phase-locked loop equations
Authors: Susuki Yoshihiko , Yokoi Yuuichi , Hikihara Takashi
Published: May 2007

This paper analyzes frequency entrainment described by van der Pol and phase-locked loop (PLL) equations. The PLL equation represents the dynamics of a PLL circuit that appear in typical phase-locking phenomena. These two equations describe frequency entrainment by a periodic force. The entrainment originates from two different types of limit cycles: libration for the van der Pol equation and rotation for the PLL one. To explore the relationship between the geometry of limit cycles and the mechanism of entrainment, we investigate the entrainment using an energy balance relation. This relation is equivalent to the energy conservation law of dynamical systems with dissipation and input terms. We show response curves for the dc component, harmonic amplitude, phase difference, and energy supplied by a periodic force. The obtained curves indicate that the entrainments for the two equations have different features of supplied energy, and that the entrainment for the PLL equation possibly has the same mechanism as does the regulation of the phase difference for the van der Pol equation.
A nonlinear dynamics method for signal identification
Authors: Carroll T. L.
Published: May 2007

When a radio frequency signal is radiated by a transmitter, the properties of the transmitter itself affect the properties of the signal. These transmitter-induced changes are known as unintentional modulation, to differentiate them from intentional modulation used to add information to the signal. The unintentional modulation can be used to identify which transmitter produced a signal. This paper shows how phase space analysis based on nonlinear dynamics ideas can be used to determine which of several amplifiers produced a signal.
Geometry of quantum active subspaces and of effective Hamiltonians
Authors: Viennot David
Published: May 2007

We propose a geometric formulation of the theory of effective Hamiltonians associated with active spaces. We analyze particularly the case of the time-dependent wave operator theory. This formulation is related to the geometry of the manifold of the active spaces, particularly to its Kählerian structure. We introduce the concept of quantum distance between active spaces. We show that the time-dependent wave operator theory is, in fact, a gauge theory, and we analyze its relationship with the geometric phase concept.
Acoustic method for measuring the sound speed of gases over small path lengths
Authors: Olfert J. S. , Checkel M. D. , Koch C. R.
Published: May 2007

Acoustic “phase shift” methods have been used in the past to accurately measure the sound speed of gases. In this work, a phase shift method for measuring the sound speed of gases over small path lengths is presented. We have called this method the discrete acoustic wave and phase detection (DAWPD) method. Experimental results show that the DAWPD method gives accurate (±3.2m∕s) and predictable measurements that closely match theory. The sources of uncertainty in the DAWPD method are examined and it is found that ultrasonic reflections and changes in the frequency ratio of the transducers (the ratio of driving frequency to resonant frequency) can be major sources of error. Experimentally, it is shown how these sources of uncertainty can be minimized.
Laptop photothermal reflectance measurement instrument assembled with optical fiber components
Authors: Yarai Atsushi , Nakanishi Takuji
Published: May 2007

In this article, we propose a laptop photothermal reflectance measurement instrument assembled with optical fiber components. The primary feature of this instrument is that all of the optical routes for the pumping and probing beams, as well as the beam sources using a laser diode, are composed of optical fiber and optical fiber components. With this configuration, the problems related to the technical shortcomings of the conventional instrument can be solved completely. Our proposed instrument is also appropriate for in situ measurement of the thermoproperties of thin film. The dimensions of our instrument’s case are 400mm wide, 250mm deep, and 60mm tall, and its weight is approximately 1kg, containing the power supply for driving the laser diode of the pumping beam and electronics for the detection of photothermal reflectance. These are at least 1∕20 and 1∕50 smaller than the volume and weight of the conventional commercial instrument, respectively. Nevertheless, it is only necessary to prepare a synchronous detection instrument for signal recovery (e.g., lock-in amplifier) with our instrument. To evaluate our instrument’s thermoproperty measurement capability, we measured the thermal diffusivity and thermal conductivity of Au thin film. The thermal diffusivity of 1.5-μm-thick Au film measured by our instrument matched previously reported values within a margin of error of a few percent.
Elimination of instabilities in phase shift curves in phase-modulation atomic force microscopy in constant-amplitude mode
Authors: Sugawara Yasuhiro , Kobayashi Naritaka , Kawakami Masayo , Li Yan Jun , Naitoh Yoshitaka , Kageshima Masami
Published: May 2007

The authors propose phase-modulation atomic force microscopy (PM-AFM) in constant-amplitude mode using automatic gain control to prevent the instabilities of cantilever dynamics. Under the condition that the driving frequency is set to the resonant frequency of the cantilever, phase shift curve in constant-amplitude mode shows no discontinuity, which resembles a typical behavior of the frequency shift curve in frequency-modulation AFM. They demonstrate that PM-AFM in constant-amplitude mode can clearly resolve phase-separated structures on polymer blend film without instability. These results indicate that PM-AFM in constant-amplitude mode is more stable than that in constant-excitation mode.
Quantitative nanoscale local strain profiling in embedded SiGe metal-oxide-semiconductor structures
Authors: Zhao W. , Duscher G. , Rozgonyi G. , Zikry M. A. , Chopra S. , Ozturk M. C.
Published: May 2007

Mechanical strain by strain engineering has been widely used in Si metal-oxide-semiconductor field effect transistors. Experimental convergent beam electron diffraction (CBED) strain measurements and finite element calculations to quantitatively correlate the strain in the transmission electron microscope (TEM) sample with the actual device. It was found that the magnitude of the longitudinal strain, εx, along the channel direction, is about 20% higher in the TEM sample than in the real device. This combined approach can be used to explain data from other CBED studies of strained Si devices.
Efficient extreme ultraviolet plasma source generated by a CO2 laser and a liquid xenon microjet target
Authors: Ueno Yoshifumi , Ariga Tatsuya , Soumagne George , Higashiguchi Takeshi , Kubodera Shoichi , Pogorelsky Igor , Pavlishin Igor , Stolyarov Daniil , Babzien Marcus , Kusche Karl , Yakimenko Vitaly
Published: May 2007

We demonstrated efficacy of a CO2-laser-produced xenon plasma in the extreme ultraviolet (EUV) spectral region at 13.5nm at variable laser pulse widths between 200ps and 25ns. The plasma target was a 30μm liquid xenon microjet. To ensure the optimum coupling of CO2 laser energy with the plasma, they applied a prepulse yttrium aluminum garnet laser. The authors measured the conversion efficiency (CE) of the 13.5nm EUV emission for different pulse widths of the CO2 laser. A maximum CE of 0.6% was obtained for a CO2 laser pulse width of 25ns at an intensity of 5×1010W∕cm2.
Cellular polyethylene-naphthalate ferroelectrets: Foaming in supercritical carbon dioxide, structural and electrical preparation, and resulting piezoelectricity
Authors: Fang P. , Wegener M. , Wirges W. , Gerhard R. , Zirkel L.
Published: May 2007

Polymer foams with electrically charged cellular voids, the so-called ferroelectrets, are soft piezoelectric transducer materials. Several polymers such as polyethylene terephthalate or cyclo-olefin copolymers are under investigation with respect to their suitability as ferroelectrets. Here, the authors report an additional ferroelectret polymer, cellular polyethylene-naphthalate (PEN), which was prepared from commercial uniform polymer films by means of foaming in supercritical carbon dioxide, inflation, biaxial stretching, electrical charging, and metallization. Piezoelectric d33 coefficients of up to 140pC∕N demonstrate the suitability of such cellular PEN films for transducer applications. Their piezoelectricity is partially stable at elevated temperatures as high as 100°C.
Multiplication of shear bands and ductility of metallic glass
Authors: Wu F. F. , Zhang Z. F. , Jiang F. , Sun J. , Shen J. , Mao S. X.
Published: May 2007

The authors find that metallic glass can be controlled to create regularly arrayed fine multiple shear bands under small punch test, indicating that metallic glass essentially has a good plastic deformation ability and thus high ductility under suitable loading condition. The current findings imply that the initiation and propagation of shear bands in metallic glass strongly depends on the stress state and the small punch test can also be regarded as an effective method to characterize the shear deformation ability and distinguish ductile-brittle transition of different metallic glasses.
Loss-of-function screening by randomized intracellular antibodies: Identification of hnRNP-K as a potential target for metastasis
Authors: Inoue Atsushi , Sawata Shinya Y. , Taira Kazunari , Wadhwa Renu
Published: May 2007

We have developed a loss-of-function screening system on the basis of intracellular expression of single domain antibodies. We demonstrate its use in identification of potential targets of metastasis of human cancerous cells. Randomized intracellular antibodies were expressed in highly metastatic cells, and a derivative pool of cells with loss of migration phenotype in chemotaxis assay was isolated. Isolation of antibodies from cells with loss of migration phenotype and identification of their target proteins revealed the involvement of the heterogeneous nuclear ribonucleoprotein K (hnRNP-K), a multifunctional signaling protein, in metastasis. Furthermore, we found that the cytoplasmic accumulation of hnRNP-K is crucial for its role in metastasis. The results demonstrate (
i
) the advantages of our functional interference screening over the gene-knockouts and gene-silencing, (
ii
) hnRNP-K as a potential target of metastasis, and (
iii
) a potential anti-metastasis peptide validated in
in vitro
cell migration assays.
Dynamical stability of Fe-H in the Earth's mantle and core regions
Authors: Isaev Eyvaz I. , Skorodumova Natalia V. , Ahuja Rajeev , Vekilov Yuri K. , Johansson Börje
Published: May 2007

The core extends from the depth of 2,900 km to the center of the Earth and is composed mainly of an iron-rich alloy with nickel, with 10% of the mass comprised of lighter elements like hydrogen, but the exact composition is uncertain. We present a quantum mechanical first-principles study of the dynamical stability of FeH phases and their phonon densities of states at high pressure. Our free-energy calculations reveal a phonon-driven stabilization of
dhcp
FeH at low pressures, thus resolving the present contradiction between experimental observations and theoretical predictions. Calculations reveal a complex phase diagram for FeH under pressure with a
dhcp
→
hcp
→
fcc
sequence of structural transitions.
Molecular evolution of affinity and flexibility in the immune system
Authors: Thorpe Ian F. , Brooks Charles L.
Published: May 2007

The immune system responds to the introduction of foreign antigens by rapidly evolving antibodies with increasing affinity for the antigen (i.e., maturation). To investigate the factors that control this process at the molecular level, we have assessed the changes in flexibility that accompany ligand binding at four stages of maturation in the 4-4-20 antibody. Our studies, based on molecular dynamics, indicate that increased affinity for the target ligand is associated with a decreased entropic cost to binding. The entropy of binding is unfavorable, opposing favorable enthalpic contributions that arise during complex formation. Computed binding free energies for the various antibody–ligand complexes qualitatively reproduce the trends observed in the experimentally derived values, although the absolute magnitude of free-energy differences is overestimated. Our results support the existence of a correlation between high-affinity interactions and decreased protein flexibility in this series of antibody molecules. This observation is likely to be a general feature of molecular association processes and key to the molecular evolution of antibody responses.
Mismatched pre- and postnatal nutrition leads to cardiovascular dysfunction and altered renal function in adulthood
Authors: Cleal Jane K. , Poore Kirsten R. , Boullin Julian P. , Khan Omar , Chau Ryan , Hambidge Oliver , Torrens Christopher , Newman James P. , Poston Lucilla , Noakes David E. , Hanson Mark A. , Green Lucy R.
Published: May 2007

The early life environment has long-term implications for the risk of developing cardiovascular (CV) disease in adulthood. Fetal responses to changes in maternal nutrition may be of immediate benefit to the fetus, but the long-term effects of these adaptations may prove detrimental if nutrition in postnatal life does not match that predicted by the fetus on the basis of its prenatal environment. We tested this predictive adaptive response hypothesis with respect to CV function in sheep. We observed that a mismatch between pre- and postnatal nutrient environments induced an altered CV function in adult male sheep that was not seen when environments were similar. Sheep that received postnatal undernutrition alone had altered growth, CV function, and basal hypothalamo–pituitary–adrenal axis activity in adulthood. Prenatal undernutrition induced greater weight gain by weaning compared with the prenatal control diet, which may provide a reserve in the face of a predicted poor diet in later life. In an adequate postnatal nutrient environment (i.e., relatively mismatched), these offspring exhibited cardiac hypertrophy and altered CV function in adulthood. These data support the concept that adult CV function can be determined by developmental responses to intrauterine nutrition made in expectation of the postnatal nutritional environment, and that if these predictions are not met, the adult may be maladapted and at greater risk of CV disease. Our findings have substantial implications for devising strategies to reduce the impact of a mismatch in nutrition levels in humans undergoing rapid socio-economic transitions in both developing and developed societies.
HIV-1 escape from the entry-inhibiting effects of a cholesterol-binding compound via cleavage of gp41 by the viral protease
Authors: Waheed Abdul A. , Ablan Sherimay D. , Roser James D. , Sowder Raymond C. , Schaffner Carl P. , Chertova Elena , Freed Eric O.
Published: May 2007

HIV-1 virions are highly enriched in cholesterol relative to the cellular plasma membrane. We recently reported that a cholesterol-binding compound, amphotericin B methyl ester (AME), blocks HIV-1 entry and that single amino acid substitutions in the cytoplasmic tail of the transmembrane envelope glycoprotein gp41 confer resistance to AME. In this study, we defined the mechanism of resistance to AME. We observed that the gp41 in AME-resistant virions is substantially smaller than wild-type gp41. Remarkably, we found that this shift in gp41 size is due to cleavage of the gp41 cytoplasmic tail by the viral protease. We mapped the protease-mediated cleavage to two sites in the cytoplasmic tail and showed that gp41 truncations in this region also confer AME resistance. Thus, to escape the inhibitory effects of AME, HIV-1 evolved a mechanism of protease-mediated envelope glycoprotein cleavage used by several other retroviruses to activate envelope glycoprotein fusogenicity. In contrast to the mechanism of AME resistance observed for HIV-1, we demonstrate that simian immunodeficiency virus can escape from AME via the introduction of premature termination codons in the gp41 cytoplasmic tail coding region. These findings demonstrate that in human T cell lines, HIV-1 and simian immunodeficiency virus can evolve distinct strategies for evading AME, reflecting their differential requirements for the gp41 cytoplasmic tail in virus replication. These data reveal that HIV-1 can escape from an inhibitor of viral entry by acquiring mutations that cause the cytoplasmic tail of gp41 to be cleaved by the viral protease.
Triggering sleep slow waves by transcranial magnetic stimulation
Authors: Massimini Marcello , Ferrarelli Fabio , Esser Steve K. , Riedner Brady A. , Huber Reto , Murphy Michael , Peterson Michael J. , Tononi Giulio
Published: May 2007

During much of sleep, cortical neurons undergo near-synchronous slow oscillation cycles in membrane potential, which give rise to the largest spontaneous waves observed in the normal electroencephalogram (EEG). Slow oscillations underlie characteristic features of the sleep EEG, such as slow waves and spindles. Here we show that, in sleeping subjects, slow waves and spindles can be triggered noninvasively and reliably by transcranial magnetic stimulation (TMS). With appropriate stimulation parameters, each TMS pulse at <1 Hz evokes an individual, high-amplitude slow wave that originates under the coil and spreads over the cortex. TMS triggering of slow waves reveals intrinsic bistability in thalamocortical networks during non-rapid eye movement sleep. Moreover, evoked slow waves lead to a deepening of sleep and to an increase in EEG slow-wave activity (0.5–4.5 Hz), which is thought to play a role in brain restoration and memory consolidation.
Telomere-associated endonuclease-deficient
Penelope
-like retroelements in diverse eukaryotes
Authors: Gladyshev Eugene A. , Arkhipova Irina R.
Published: May 2007

The evolutionary origin of telomerases, enzymes that maintain the ends of linear chromosomes in most eukaryotes, is a subject of debate.
Penelope
-like elements (PLEs) are a recently described class of eukaryotic retroelements characterized by a GIY-YIG endonuclease domain and by a reverse transcriptase domain with similarity to telomerases and group II introns. Here we report that a subset of PLEs found in bdelloid rotifers, basidiomycete fungi, stramenopiles, and plants, representing four different eukaryotic kingdoms, lack the endonuclease domain and are located at telomeres. The 5′ truncated ends of these elements are telomere-oriented and typically capped by species-specific telomeric repeats. Most of them also carry several shorter stretches of telomeric repeats at or near their 3′ ends, which could facilitate utilization of the telomeric G-rich 3′ overhangs to prime reverse transcription. Many of these telomere-associated PLEs occupy a basal phylogenetic position close to the point of divergence from the telomerase-PLE common ancestor and may descend from the missing link between early eukaryotic retroelements and present-day telomerases.
Multitrophic interaction facilitates parasite–host relationship between an invasive beetle and the honey bee
Authors: Torto Baldwyn , Boucias Drion G. , Arbogast Richard T. , Tumlinson James H. , Teal Peter E. A.
Published: May 2007

Colony defense by honey bees,
Apis mellifera
, is associated with stinging and mass attack, fueled by the release of alarm pheromones. Thus, alarm pheromones are critically important to survival of honey bee colonies. Here we report that in the parasitic relationship between the European honey bee and the small hive beetle,
Aethina tumida
, the honey bee's alarm pheromones serve a negative function because they are potent attractants for the beetle. Furthermore, we discovered that the beetles from both Africa and the United States vector a strain of
Kodamaea ohmeri
yeast, which produces these same honey bee alarm pheromones when grown on pollen in hives. The beetle is not a pest of African honey bees because African bees have evolved effective methods to mitigate beetle infestation. However, European honey bees, faced with disease and pest management stresses different from those experienced by African bees, are unable to effectively inhibit beetle infestation. Therefore, the environment of the European honey bee colony provides optimal conditions to promote the unique bee–beetle–yeast–pollen multitrophic interaction that facilitates effective infestation of hives at the expense of the European honey bee.
Madeline 2.0 PDE: a new program for local and web-based pedigree drawing
Authors: Trager Edward H. , Khanna Ritu , Marrs Adrian , Siden Lawrence , Branham Kari E.H. , Swaroop Anand , Richards Julia E.
Published: May 2007

Summary: The Madeline 2.0 Pedigree Drawing Engine (PDE) is a pedigree drawing program for use in linkage and family-based association studies. The program is designed to handle large and complex pedigrees with an emphasis on readability and aesthetics. For complex pedigrees, we use a hybrid algorithm in which consanguinous loops are drawn as cyclic graphs whenever possible, but we resort to acyclic graphs when matings can no longer be connected without line crossings. A similar hybrid approach is used to avoid line crossings for matings between distant descendants of different founding groups. Written in object-oriented C++ and released under the GNU General Public License (GPL), Madeline 2.0 PDE reads input files specified on the command line and generates pedigree drawings without user interaction. Pedigree output in scalable vector graphics (SVG) format can be viewed in browsers with native SVG rendering support or in vector graphics editors. We provide an easy-to-use public web service, which is experimental and still under development.

Availability:  http://kellogg.umich.edu/madeline

Contact:  ed.trager@gmail.com
MODELER4SIMCOAL2: A user-friendly, extensible modeler of demography and linked loci for coalescent simulations
Authors: Antao T. , Beja-Pereira A. , Luikart G.
Published: May 2007

Summary: MODELER4SIMCOAL2 (M4S2) is an extensible graphical tool to model linked loci and population demographies. M4S2 is easy to use, allowing for the modeling of complicated scenarios, making coalescent simulation modeling accessible to biologists with limited computer skills. The software includes an extension system allowing for new models to be created, published and downloaded from the Internet.

Availability: M4S2 is available from http://popgen.eu/soft/m4s2 under a GPL license. The web site also contains guides, screen shots and tutorials.

Contact:  tra@fc.up.pt
Pearl Millet as a Rotation Crop for Peanut
Authors: Timper Patricia , Brenneman Timothy B. , Wilson Jeffrey P.
Published: May 2007

In the southeastern United States, there are limited options for crops that can be grown in rotation with peanut (Arachis hypogaea). Pearl millet (Pennisetum glaucum) has potential as a grain crop, and some hybrids have shown resistance to the peanut root-knot nematode (Meloidogyne arenaria), the primary nematode pest of peanut in this region. The objective of this study was to determine whether pearl millet reduces M. arenaria when planted in rotation with peanut. The experiment was arranged as a randomized, complete-block design with six replications. The rotations were peanut following either 2 years of corn, HGM-100 pearl millet, or TifGrain 102 pearl millet. There were two staggered sequences of each rotation so that a cycle was completed in 2004 and in 2005. Pearl millet did not increase either stem rot or Rhizoctonia limb rot in peanut. In both years, root galling from M. arenaria was lower on peanut following TifGrain 102 (4.6 on a scale of 0 to 10) and corn (4.9) than following HGM-100 (7.5). Peanut yields in 2004 were low and unaffected by the preceding rotation crop; however, in 2005, yields were greater in peanut following 2 years of TifGrain 102 (2320 kg/ha) and corn (2504 kg/ha) than following HGM-100 (1821 kg/ha). The lower yields following HGM-100 were likely due to greater populations of M. arenaria that had developed on the susceptible pearl millet hybrid. Economic analyses showed greater returns above variable costs from the grain crops than from the peanut crops. We conclude that the resistant pearl millet hybrid TifGrain 102 is as effective as corn in limiting population increase of M. arenaria and in enhancing peanut yield compared to the susceptible pearl millet hybrid, HGM-100. Additional research is needed to improve the profitability of pearl millet, and nematode resistance should be an important component of crop improvement programs.

Accepted for publication 20 October 2006. Published 2 February 2007.
Efficacy of Insecticides for Control of Insect Pests of Pearl Millet for Grain Production
Authors: Buntin G. David , Hanna Wayne A. , Wilson Jeffrey P. , Ni Xinzhi
Published: May 2007

Pearl millet [Pennisetum glaucum (L.) R. Br.] is an alternative drought-tolerant grain crop for dryland summer production. Few insecticides are registered for use and insect management has not been extensively studied in pearl millet for grain production. Eleven trails were conducted during 2002-2004 in central and southern Georgia to understand the relative importance of insect pests and to evaluate the efficacy of currently registered insecticides against key pests. The main defoliator species were the fall armyworm [Spodoptera frugiperda (J.E. Smith)] and striped grassworm (Mocis latipes Guenée). Main insects feeding on grain heads were the corn earworm (Helicoverpa zea Boddie), sorghum webworm, (Nola sorghiella Riley), and stink bugs — brown stink bug (Euschistus spp.) and southern green stink bug [Nezara viridula (L.)]. All insects were effectively controlled by cypermethrin at 0.025 lb a.i./acre. The 0.015-lb a.i. rate was effective against sorghum webworm, striped grassworm, and stink bugs, but efficacy against the corn earworm was variable. Spinosad was effective against corn earworm, striped grassworm, and sorghum webworm but not against stink bugs. Azadirachtin was not effective against any insect tested. Grain yield was not significantly affected by treatments in any trial indicating that pearl millet is tolerant of insect injury. Further work will be needed to define economic thresholds for key insect pests of pearl millet for grain production.

Accepted for publication 24 August 2006. Published 19 February 2007.
First North American Record of Powdery Mildew of Cleome hassleriana Caused by Leveillula taurica
Authors: Sampangi R. , Glawe D. A. , Mohan S. K.
Published: May 2007

This report documents the first record of Leveillula taurica on a species of Cleome (spiderflower) in North America. The introduced plant pathogen Leveillula taurica (Lév.) G. Arnaud (anamorph = Oidiopsis sicula Scalia) occurs on a range of hosts in the Pacific Northwest (PNW), including onion and was identified infecting Cleome hassleriana Chod. (common name: pink queen, family: Capparaceae).

Accepted for publication 29 December 2007. Published 19 February 2007.
The pluses and minuses of0
Authors: Roberts M.G
Published: May 2007

The concept of the basic reproduction number (0) occupies a central place in epidemic theory. The value of0determines the proportion of the population that becomes infected over the course of a (modelled) epidemic. In many models, (i) an endemic infection can persist only if0>1, (ii) the value of0provides a direct measure of the control effort required to eliminate the infection, and (iii) pathogens evolve to maximize their value of0. These three statements are not universally true. In this paper, some exceptions to them are discussed, based on the extensions of the SIR model.
Rapid concerted evolution in animal mitochondrial DNA
Authors: Tatarenkov Andrey , Avise John C
Published: May 2007

Recombinational genetic processes are thought to be rare in the uniparentally inherited mitochondrial (mt) DNA molecules of vertebrates and other animals. Here, however, we document extremely rapid concerted microevolution, probably mediated by frequent gene conversion events, of duplicated sequences in the mtDNA control region of mangrove killifishes (Kryptolebias marmoratus). In local populations, genetic distances between paralogous loci within an individual were typically smaller (and often zero) than those between orthologous loci in different specimens. These findings call for the recognition of concerted evolution as a microevolutionary process and gene conversion as a likely recombinational force in animal mtDNA. The previously unsuspected power of these molecular phenomena could greatly impact mtDNA dynamics within germ cell lineages and in local animal populations.
Natural variation in Drosophila larval reward learning and memory due to a cGMP-dependent protein kinase
Authors: Kaun Karla R. , Hendel Thomas , Gerber Bertram , Sokolowski Marla B.
Published: May 2007

Animals must be able to find and evaluate food to ensure survival. The ability to associate a cue with the presence of food is advantageous because it allows an animal to quickly identify a situation associated with a good, bad, or even harmful food. Identifying genes underlying these natural learned responses is essential to understanding this ability. Here, we investigate whether natural variation in the foraging (for) gene in Drosophila melanogaster larvae is important in mediating associations between either an odor or a light stimulus and food reward. We found that for influences olfactory conditioning and that the mushroom bodies play a role in this for-mediated olfactory learning. Genotypes associated with high activity of the product of for, cGMP-dependent protein kinase (PKG), showed greater memory acquisition and retention compared with genotypes associated with low activity of PKG when trained with three conditioning trials. Interestingly, increasing the number of training trials resulted in decreased memory retention only in genotypes associated with high PKG activity. The difference in the dynamics of memory acquisition and retention between variants of for suggests that the ability to learn and retain an association may be linked to the foraging strategies of the two variants.
Rapid forgetting of social transmission of food preferences in aged rats: Relationship to hippocampal CREB activation
Authors: Countryman Renee A. , Gold Paul E.
Published: May 2007

A major characteristic of age-related changes in memory in rodents is an increase in the rate of forgetting of new information, even when tests given soon after training reveal intact memory. Interference with CREB functions similarly results in rapid decay of memory. Using quantitative immunocytochemistry, the present experiment examined the number of CREB- and pCREB-immunoreactive neurons in three regions of the dorsal and ventral hippocampus (dentate gyrus, CA3, and CA1) as a function of age and training. Rats were trained in a social transmission of food preference task. Using different food pairings, memory was tested in each rat immediately and 1, 2, 3, and 7 d later. Both young and old rats had intact and comparable memory scores at the immediate and 24-h tests, but old rats exhibited more rapid forgetting thereafter relative to that of young rats. The main findings were that training resulted in large increases in the number of pCREB-immunoreactive cells throughout the hippocampus in both young and aged rats. However, particularly in the ventral hippocampus, the training-elicited increase in pCREB-positive neurons was significantly lower in old than in young rats. Based on Western blot analyses in a separate set of rats, CREB levels were not responsive to training but were lower in the ventral hippocampus of old rats than of young rats. The present findings suggest that lower activation of CREB after training may contribute to the rapid forgetting seen in aged rats.
Corticosterone time-dependently modulates β-adrenergic effects on long-term potentiation in the hippocampal dentate gyrus
Authors: Pu Zhenwei , Krugers Harm J. , Joëls Marian
Published: May 2007

Previous experiments in the hippocampal CA1 area have shown that corticosterone can facilitate long-term potentiation (LTP) in a rapid non-genomic fashion, while the same hormone suppresses LTP that is induced several hours after hormone application. Here, we elaborated on this finding by examining whether corticosterone exerts opposite effects on LTP depending on the timing of hormone application in the dentate gyrus as well. Moreover, we tested rapid and delayed actions by corticosterone on β-adrenergic-dependent changes in LTP. Unlike the CA1 region, our in vitro field potential recordings show that rapid effects of corticosterone do not influence LTP induced by mild tetanization in the hippocampal dentate gyrus, unless GABAA receptors are blocked. In contrast, the β-adrenergic agonist isoproterenol does initiate a slow-onset, limited amount of potentiation. When corticosterone was applied concurrently with isoproterenol, a further enhancement of synaptic strength was identified, especially during the early stage of potentiation. Yet, treatment with corticosterone several hours in advance of isoproterenol fully prevented any effect of isoproterenol on LTP. This emphasizes that corticosterone can regulate β-adrenergic modulation of synaptic plasticity in opposite directions, depending on the timing of hormone application.
Are eggshell spottiness and colour indicators of health and condition in blue tits Cyanistes caeruleus?
Authors: Martínez‐de la Puente Josué , Merino Santiago , Moreno Juan , Tomás Gustavo , Morales Judith , Lobato Elisa , García‐Fraile Sonia , Martínez Javier
Published: May 2007

We explore the relationship between general eggshell colour (background and spots) and proportion of surface covered by spots on the eggs of blue tits Cyanistes caeruleus and several variables reflecting female health and condition. Females laying more spotted eggs showed a poorer body condition, higher cellular concentration of the stress protein HSP70 and marginally lower total immunoglobulin levels in blood. In addition, these females were paired with males with higher levels of HSP70 and lower concentrations of immunoglobulins. We interpret these results based on the properties of the eggshell pigment protoporphyrin, which is known as an inductor of oxidative stress in females. Although observational, this study presents, for the first time, clear evidence of eggshell spottiness and general colour as indicators of general condition and stress in avian populations.
Bile duct brushings cytology – improving sensitivity of diagnosis using the ThinPrep® technique: a review of 113 cases
Authors: Sheehan M. M. , Fraser A. , Ravindran R. , McAteer D.
Published: May 2007

Objective:  Common bile duct (CBD) brushings have been recognized as a technique of moderate sensitivity and high specificity in identifying carcinoma of the ampulla and pancreatico‐biliary regions. This study evaluated the increase in sensitivity of this technique using the ThinPrep® technique of specimen preparation when compared with conventional cytology smears.

Methods:  A total of 113 bile duct brushings were included in the study (38 conventional smears and 75 slides prepared using the ThinPrep® technique). All slides were reviewed by one cytologist. Five categories of reporting were used: inadequate, negative, atypia, suspicious and malignant.

Results:  The inadequate category of reporting disappeared in the ThinPrep® group with improved specimen fixation and preparation and hence reduced artefact. Sensitivity of diagnosis of malignancy increased from 39% in conventional smears to 53% in the ThinPrep® group. Specificity, positive and negative predictive values and accuracy were 100%, 100%, 60% and 68% for conventional smears and were 100%, 100%, 60% and 72%, respectively, for ThinPrep® specimens.

Conclusions:  ThinPrep® technique was associated with increased sensitivity of diagnosis, in part due to improved specimen fixation and reduced artefact. Cytology of bile duct brushings is an important diagnostic tool for sites from which it can be difficult to obtain a histology biopsy. It may therefore provide the only opportunity for tissue diagnosis of carcinoma from these sites, hence the importance of optimizing sensitivity.