bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling quasi‐specular scattering from the surface of Titan
Authors: Sultan‐Salem Ahmed K. , Tyler G. Leonard
Published: May 2007

The Cassini spacecraft obtained several scattering observations of the surface of Titan. Four data sets, TA‐Inbound, TA‐Outbound, T3‐Outbound, and T8‐Inbound, include scatterometer data for small angles of incidence. Analysis of these data sets provides an example use of a new generalized fractal‐based quasi‐specular scattering law that gives the surface RMS slope as a function of horizontal scale and covers a wide range of scattering behavior using a small number of parameters. The data have a significant diffuse scattering component which is modeled with the empirical cosine law, A cosn θ. The reflectivity and RMS surface parameters are retrieved from the quasi‐specular scattering model. The average RMS slope for the four data sets is about 4.2° at a horizontal scale of 5λ; λ ≈ 2.18 cm. The Fresnel power reflection coefficient ρ is approximately equal to 0.085 (corresponding to a dielectric constant εr ≈ 3.3) for TA‐Outbound and T3‐Outbound and 0.034 (εr ≈ 2.1) for TA‐Inbound and T8‐Inbound. Inadequate modeling of diffuse scattering by the cosine law results in increased uncertainties in the inferred surface parameters, especially ρ, and, consequently, in inferences of the surface composition.
Insights into subduction‐related uplift along the Hikurangi Margin, New Zealand, using numerical modeling
Authors: Litchfield Nicola , Ellis Susan , Berryman Kelvin , Nicol Andrew
Published: May 2007

We investigate the causes of regional uplift along the Hikurangi Margin (North Island, New Zealand). Late Quaternary rock uplift rates and postglacial fluvial incision rates delineate broad changes in rock uplift pattern along the margin. Comparison with the Neogene rock uplift rates, the erosion surface on basement, and the margin morphology suggests that these uplift patterns are long‐lived and relate to deep‐seated subduction processes. We use two‐dimensional numerical (finite element) models to place constraints on margin geometry and uplift rates resulting from subduction processes inferred to drive regional uplift. The models indicate that subduction of relatively buoyant and thick Hikurangi Plateau crust is the most likely mechanism for low rates (<1 mm yr−1) of uplift along the entire margin. Sediment underplating is probably the major cause of higher rates of uplift of the central and northern axial ranges (2–4 mm yr−1). Seamount subduction could account for short wavelength zones of higher uplift rate on the order of 1 mm yr−1 and could contribute to tectonic erosion, which may be driving uplift in the northern margin. This study shows the value of using numerical models to link regional patterns of rock uplift and surface morphology to deep‐seated subduction processes.
Extracting coherent regional information from local measurements with Karhunen‐Loève transform: Case study of an alluvial aquifer (Rhine valley, France and Germany)
Authors: Longuevergne Laurent , Florsch Nicolas , Elsass Philippe
Published: May 2007

We investigate the ability of combining the Karhunen‐Loève transform (KLT) with the kriging method to extract regional information from a set of point measurements. This method was applied to a set of 195 piezometric head time series over a period of 17 years from observation wells distributed within the French and German area of the Rhine valley alluvial groundwater body. Piezometric head time series are analyzed with KLT in order to highlight characteristic temporal signals, classified from the most energetic (global) to the least energetic (local) signals. The first five signals amount to 80% of the global variance of the system and are inferred to represent different hydrological contributions (exchanges with rivers and rainfall), but they also represent a significant anthropogenic component. Kriging is then used to regionalize the signals and to build a reconstruction model of the behavior of the whole aquifer containing only filtered information coming from identified source signals.
Analyzing spatial and temporal variability of annual water‐energy balance in nonhumid regions of China using the Budyko hypothesis
Authors: Yang Dawen , Sun Fubao , Liu Zhiyu , Cong Zhentao , Ni Guangheng , Lei Zhidong
Published: May 2007

On the basis of long time series of climate and discharge in 108 nonhumid catchments in China this study analyzes the spatial and temporal variability of annual water‐energy balance using the Budyko hypothesis. For both long‐term means and annual values of the water balances in the 108 catchments, Fu's formula derived from the Budyko hypothesis is confirmed. A high correlation and relatively small systematic error between the values of parameter ϖ in Fu's equation optimized from the water balance of individual year and calibrated from the long‐term mean water balance show that Fu's equation can be used for predicting the interannual variability of regional water balances. It has been found that besides the annual climate conditions the regional pattern of annual water‐energy balance is also closely correlated with the relative infiltration capacity (Ks/ir), relative soil water storage (Smax/E0), and the average slope (tan β). This enables one to estimate the parameter ϖ from catchment characteristics without calibration from the long time series of water balances. An empirical formula for the parameter ϖ in terms of the dimensionless landscape parameters is proposed. Applications of Fu's equation together with the parameter ϖ estimated by this empirical formula have shown that Fu's equation can predict both long‐term mean and annual value of actual evapotranspiration accurately and predict both long‐term mean and interannual variability of runoff reasonably. This implies that the Fu's equation can be used for predicting the annual water balance in ungauged basins.
A new feedback on climate change from the hydrological cycle
Authors: Williams Paul D. , Guilyardi Eric , Sutton Rowan , Gregory Jonathan , Madec Gurvan
Published: May 2007

An intensification of the hydrological cycle is a likely consequence of global warming. But changes in the hydrological cycle could affect sea‐surface temperature by modifying diffusive ocean heat transports. We investigate this mechanism by studying a coupled general circulation model sensitivity experiment in which the hydrological cycle is artificially amplified. We find that the amplified hydrological cycle depresses sea‐surface temperature by enhancing ocean heat uptake in low latitudes. We estimate that a 10% increase in the hydrological cycle will contribute a basin‐scale sea‐surface temperature decrease of around 0.1°C away from high latitudes, with larger decreases locally. We conclude that an intensified hydrological cycle is likely to contribute a weak negative feedback to anthropogenic climate change.
From steep‐slope volcano to flat caldera floor
Authors: Barde‐Cabusson Stéphanie , Merle Olivier
Published: May 2007

Most laboratory experiments of caldera collapse have dealt with reservoir emptying below a flat‐lying overburden without an overlying analogue volcanic edifice on top. The overload and the role of topography are then neglected so that the final flat floor within the caldera is directly linked to the initial one. In addition, caldera subsidence is commonly attributed to the collapse of the top of a magma chamber linked to eruptions delivering large amounts of volcanic products. Analogue experiments show that the deformation of a weak clay‐rich core resulting from the hydrothermal alteration in a volcanic edifice can, in certain conditions, reproduce the structures of a caldera. In particular, it is a way to explain the flat floor of a caldera when resurfacing resulting from new eruptions or destructive processes seems unlikely.
Detection and quantification of IgM+ lymphocytes in fetal lamb spleen, liver and lymph nodes by flow cytometry
Authors: Alitheen Noorjahan , McClure Susan , McCullagh Peter
Published: May 2007

The first stage in Peyer's patch development in the fetal lamb is characterized by the colonization of the rudimentary Peyer's patches by precursor cells expressing the IgM surface receptor. In the fetal lamb, the spleen has been implicated as the source of gene‐rearranged IgM+ B lymphocytes. This study was intended to quantitate IgM+ lymphocytes in the spleen, lymph nodes and liver of fetal lambs at various gestational ages between 63 and 110 days using flow cytometry. Flow‐cytometric analysis revealed that IgM+ lymphocytes were rare in the liver being consistently less than 1% at every gestational age examined. IgM+ lymphocytes were detected in the spleen (mean 9.18%) and prescapular lymph nodes (mean 11.89%) as early as 63 days. In both spleen and lymph nodes, the highest representation of IgM+ lymphocytes occurred between 70 and 86 days gestation. The highest mean percentage of IgM+ lymphocytes was observed in the spleen (22.63%) and lymph nodes (17.02%) at 75 days gestation. From 98 days onwards, B‐lymphocyte density gradually decreased in both spleen and prescapular lymph nodes. This study indicates that substantial populations of IgM+ lymphocytes were present in both the spleen and prescapular lymph nodes from 70 days gestation and implies that both of these locations could be potential sources for the normal colonization of the ileal Peyer's patches.
From Origins to Implications: Key Aspects in the Debate over the Digital Divide
Authors: James Jeffrey
Published: May 2007

Defined as the differential extent to which rich countries and poor countries benefit from various forms of information technology (IT), the global digital divide has been extensively measured and described in national as well as international debates. The problem, however, is that the topic is highly fragmented in the literature, with few attempts to put the parts into a coherent analytical framework. More precisely, there has been no specific attempt to pinpoint the main issues that influence one's view of the importance of the digital divide and the policies demanded by the different points of view. The goal of this paper, accordingly, is to fill this important gap in the literature in an analytical schema that recognizes the ways in which the impact of innovations depends heavily on how they are generated and diffused. At each stage of this sequential process are key issues that influence one's view of the digital divide. It matters a great deal for instance on whether the divide is in some sense unique, or just another manifestation of the general technological relationship between rich and poor countries. It is also the case that the size of the divide depends heavily on how it is measured. Yet another example is that the extent of the potential impact of IT will influence our view of the foregone opportunities associated with limited uptake of this technology in developing countries.
Memory effect and inverse thermal hysteresis in La0.87Mn0.98Fe0.02Ox
Authors: De K. , Majumdar S. , Giri S.
Published: May 2007

We have investigated electrical transport and magnetization studies as a function of temperature, magnetic field, and time for polycrystalline La0.87Mn0.98Fe0.02Ox. The temperature dependence of resistivity exhibits a bifurcation in the zero-field cooled and field-cooled behavior below the paramagnetic to ferromagnetic transition temperature (Tc≈205 K). We observe an inverse thermal hysteresis in field-cooled resistivity in the temperature range of 85–200 K. Similar thermal hysteresis in the field-cooled magnetization is also observed. In consistence with the thermal hysteresis, the relaxation of magnetization exhibits the different magnetic characteristics in the heating and cooling cycles. The sample shows interesting memory effect in the relaxation of field-cooled resistivity. The magnetoresistance and magnetization studies suggest that the above unusual features are ascribed to the inhomogeneous structural phase separation in the case of minor Fe substitution.
Enhancement of upconverted luminescence in Er3+:TeO2 glass on increasing the temperature and concentration of Yb3+ beyond the critical limit
Authors: Singh Anant Kumar , Tripathi Garima , Rai S. B. , Rai Anita
Published: May 2007

Enhancement of upconverted luminescence in Er3+∕Yb3+:TeO2 has been observed with increase in the concentration of Yb3+ on excitation with 780nm laser radiation. It is further noted that the upconversion is increased even above the quenching limit on increasing the temperature of the glass. The incident radiation excites Yb3+ indirectly via Er3+ resulting in a strong blue emission from Yb3+ and green and red emissions from Er3+. The UV emission from Er3+ at 380nm involves three near infrared photons when there is no Yb3+ in the glass but when Yb3+ is also present, this behaves as a two photon process. The lifetime of the S3∕24 level of Er3+ in glasses containing only Er3+ and also those containing both Er3+ and Yb3+ has also been measured in different conditions.
Q
-branch linewidths of N2 perturbed by H2: Experiments and quantum calculations from an ab initio potential
Authors: Gómez Laura , Martínez Raúl Z. , Bermejo Dionisio , Thibault Franck , Joubert Pierre , Bussery-Honvault Béatrice , Bonamy Jeanine
Published: May 2007

In this work the authors present an experimental and theoretical study about the Q-branch lines’ broadening coefficients of N2 perturbed by H2. Experimental values for these parameters have been obtained at 440 and 580K, and quantum calculations have been performed using a new ab initio potential energy surface, obtained by quantum chemistry methods. The results of these calculations are compared to experimental data obtained previously at 77 and 298K [L. Gomez et al., Mol. Phys. 104, 1869 (2006)] and to the present measurements. A satisfactory agreement is obtained for the whole range of temperatures used in the experiments.
Evaluation of metal-free carbon nanotubes formed by SiC thermal decomposition
Authors: Harrison Jeremy , Sambandam Senthil N. , Boeckl John J. , Mitchel W. C. , Collins W. E. , Lu Weijie
Published: May 2007

Thermal decomposition on SiC surface at high temperature and at low residual oxygen pressure yields a thin film of metal-free carbon nanotubes (CNTs) aligned on the SiC. In this study, CNT films on carbon-face 4H-SiC are produced under vacuum from 10−3to10−7Torr and at temperatures ranging from 1400to1700°C. Ex situ spectroscopic ellipsometry (SE) technique is applied to investigate the structure of the CNT films. It is found that two thin interfacial layers on the top and bottom of the CNTs are crucial in modeling the film structure from the SE data. We suggest a five layer structural model that consists of a CNT film as the main component, two interfacial layers, an amorphous carbon layer, and a surface roughness layer. This structural model based on the SE measurements is confirmed by cross-section transmission electron microscopy and can be applied for all CNT/SiC structures grown at various pressures and temperatures. At the growth pressure of 10−5Torr, the CNT layer on SiC consists of 30%–50% CNTs, 35%–60% voids, and 5%–12% amorphous carbon in volume.
Adiabatic nanofocusing of plasmons by a sharp metal wedge on a dielectric substrate
Authors: Vernon Kristy C. , Gramotnev Dmitri K. , Pile David F. P.
Published: May 2007

We demonstrate that efficient adiabatic nanofocusing of plasmons can be achieved using a sharp metal wedge (thin tapered film) on a dielectric substrate. It is shown that the quasisymmetric (with respect to the charge distribution across the wedge) plasmon mode can experience infinite adiabatic slowing down with both its phase and group velocities reducing to zero as the plasmon propagates towards the tip of the wedge. Conditions for strong local field enhancement near the tip are determined and analyzed. In particular, it is demonstrated that the electric field in the plasmon experiences much stronger local enhancement than the magnetic field. Two distinct asymptotic regimes with the electric field amplitude approaching either zero or infinity at the tip of the wedge (tapered film) are described. The results are compared to adiabatic nanofocusing of plasmons by metallic V grooves and sharp metal wedges in a uniform dielectric.
Raman microprobe characterization of electrodeposited S-rich CuIn(S,Se)2 for photovoltaic applications: Microstructural analysis
Authors: Izquierdo-Roca V. , Pérez-Rodríguez A. , Romano-Rodríguez A. , Morante J. R. , Álvarez-García J. , Calvo-Barrio L. , Bermudez V. , Grand P. P. , Ramdani O. , Parissi L. , Kerrec O.
Published: May 2007

This article reports a detailed Raman scattering and microstructural characterization of S-rich CuIn(S,Se)2 absorbers produced by electrodeposition of nanocrystalline CuInSe2 precursors and subsequent reactive annealing under sulfurizing conditions. Surface and in-depth resolved Raman microprobe measurements have been correlated with the analysis of the layers by optical and scanning electron microscopy, x-ray diffraction, and in-depth Auger electron spectroscopy. This has allowed corroboration of the high crystalline quality of the sulfurized layers. The sulfurizing conditions used also lead to the formation of a relatively thick MoS2 intermediate layer between the absorber and the Mo back contact. The analysis of the absorbers has also allowed identification of the presence of In-rich secondary phases, which are likely related to the coexistence in the electrodeposited precursors of ordered vacancy compound domains with the main chalcopyrite phase, in spite of the Cu-rich conditions used in the growth. This points out the higher complexity of the electrodeposition and sulfurization processes in relation to those based in vacuum deposition techniques.
Fabrication of highly conductive Ti1−xNbxO2 polycrystalline films on glass substrates via crystallization of amorphous phase grown by pulsed laser deposition
Authors: Hitosugi T. , Ueda A. , Nakao S. , Yamada N. , Furubayashi Y. , Hirose Y. , Shimada T. , Hasegawa T.
Published: May 2007

Nb-doped anatase TiO2 [Ti0.94Nb0.06O2 (TNO)] films with high electrical conductivity and transparency were fabricated on nonalkali glass using pulsed laser deposition and subsequent annealing in a H2 atmosphere. The amorphous films as deposited on unheated substrates were found to crystallize, forming polycrystalline films at around 350°C. The films annealed at 500°C showed resistivity down to 4.6×10−4Ωcm at room temperature and optical transmittance of 60%–80% in the visible region, which are comparable to those of epitaxial films. These results indicate that TNO films have the potential to be practical transparent conducting oxides that could replace indium tin oxide.
Using double layer CoSi2 nanocrystals to improve the memory effects of nonvolatile memory devices
Authors: Yang F. M. , Chang T. C. , Liu P. T. , Yeh P. H. , Chen U. S. , Yu Y. C. , Lin J. Y. , Sze S. M. , Lou J. C.
Published: May 2007

The nonvolatile memory device with multilayer nanocrystals has advantages such as the memory effects can be increased by the increasing density of the nanocrystals and the whole retention characteristic can be improved. There are much more electrons that can be stored in the double layer than single layer nanocrystal memory device. The double layer CoSi2 nanocrystals have better retention characteristic than the single layer. The good retention characteristic of the double layer device is due to the Coulomb-blockage effects on the top layer nanocrystals from the bottom layer nanocrystals. So, the memory effects of the nonvolatile memory device can be improved by using the double layer nanocrystals.
Self-homodyne rf demodulator using a ferromagnetic nanowire
Authors: Yamaguchi A. , Miyajima H. , Kasai S. , Ono T.
Published: May 2007

The radio frequency (rf) demodulator using a spin-torque diode effect in a single ferromagnetic nanowire is proposed. This is the first self-homodyne rf demodulator with ferromagnetic nanowire, and it can demodulate the amplitude modulation rf signal whose baseband frequency corresponds to the ferromagnetic resonance frequency of the wire.
Phase-contrast x-ray imaging with intense ArKα radiation from femtosecond-laser-driven gas target
Authors: Chen L. M. , Kando M. , Ma J. , Kotaki H. , Fukuda Y. , Hayashi Y. , Daito I. , Homma T. , Ogura K. , Mori M. , Pirozhkov A. S. , Koga J. , Daido H. , Bulanov S. V. , Kimura T. , Tajima T. , Kato Y.
Published: May 2007

Intense ArKα x ray with very little continuum background has been generated using a dense Ar gas irradiated with an intense femtosecond laser, with the measured flux of 1.2×103photons∕mrad2/pulse. This compact quasimonochromatic x-ray source, with a source size of only 12μm, has been applied to x-ray radiographic imaging of a biological specimen, resulting in high-resolution, high quality phase-contrast images. Correlation between this intense Kα emission with the laser channeling in the Ar gas is discussed.
Imaging of acoustic pressure radiation from vibrating microstructure in atmosphere using thermal microprobe
Authors: Ono Takahito , Kim Sang-Jin , Esashi Masayoshi
Published: May 2007

This letter reports on an imaging technique of acoustic pressure radiation (APR) from vibrating micro-/nanostructures and their mechanical defects. Resonance oscillation of micro-/nanometer beams in use of viscous environments is important for various sensing applications. Viscous dumping is the main energy loss mechanism, which determines the quality factor of resonance in viscous fluid. The APR due to viscous dumping is imaged using a scanning thermal flow sensor. A platinum heater or micromachined silicon heater is heated up by flowing a current, and the acoustic particle velocity which originated from APR is detected. Imaging of APR is demonstrated and compared with the actual vibration image. Also, strong APR is observed from a crack on the support of a silicon beam.
The effect of coating in increasing the critical size of islands on a compliant substrate
Authors: Yoon Juil , Zhang Zhen , Lu Nanshu , Suo Zhigang
Published: May 2007

A flexible electronic system may consist of a polymeric substrate and an array of stiff islands, on which devices are fabricated. When the substrate is stretched, the devices on the islands experience small strains but the islands may debond if they exceed a critical size. The authors show that a thin layer of polymer coating, covering the islands and the substrate, can markedly increase the critical island size.
Angle Discrimination in Raised-Line Drawings
Authors: Wijntjes Maarten W A , Kappers Astrid M L
Published: May 2007

We investigated the angular resolution subserving the haptic perception of raised-line drawings by measuring how accurately observers could discriminate between two angle sizes under various conditions. We found that, for acute angles, discrimination performance is highly dependent on exploration strategy: mean thresholds of 2.9° and 6.0° were found for two different exploration strategies. For one of the strategies we found that discriminability is not dependent on the bisector orientation of the angle. Furthermore, we found that thresholds almost double when the angular extent is increased from 20° to 135°. We also found that local apex information has a significant influence on discrimination for acute as well as obtuse angles. In the last experiment we investigated the influence of depiction mode but did not find any effect. Overall, the results tell us that the acuity with which angles in raised-line drawings are perceived is determined by the exploration strategy, local apex information, and global angular extent.
Density-equalizing Euclidean minimum spanning trees for the detection of all disease cluster shapes
Authors: Wieland Shannon C. , Brownstein John S. , Berger Bonnie , Mandl Kenneth D.
Published: May 2007

Existing disease cluster detection methods cannot detect clusters of all shapes and sizes or identify highly irregular sets that overestimate the true extent of the cluster. We introduce a graph-theoretical method for detecting arbitrarily shaped clusters based on the Euclidean minimum spanning tree of cartogram-transformed case locations, which overcomes these shortcomings. The method is illustrated by using several clusters, including historical data sets from West Nile virus and inhalational anthrax outbreaks. Sensitivity and accuracy comparisons with the prevailing cluster detection method show that the method performs similarly on approximately circular historical clusters and greatly improves detection for noncircular clusters.
Strongly emissive individual DNA-encapsulated Ag nanoclusters as single-molecule fluorophores
Authors: Vosch Tom , Antoku Yasuko , Hsiang Jung-Cheng , Richards Chris I. , Gonzalez Jose I. , Dickson Robert M.
Published: May 2007

The water-soluble, near-IR-emitting DNA-encapsulated silver nanocluster presented herein exhibits extremely bright and photostable emission on the single-molecule and bulk levels. The photophysics have been elucidated by intensity-dependent correlation analysis and suggest a heavy atom effect of silver that rapidly depopulates an excited dark level before quenching by oxygen, thereby conferring great photostability, very high single-molecule emission rates, and essentially no blinking on experimentally relevant time scales (0.1 to >1,000 ms). Strong antibunching is observed from these biocompatible species, which emit >10
9
photons before photobleaching. The significant dark-state quantum yield even enables bunching from the emissive state to be observed as a dip in the autocorrelation curve with only a single detector as the dark state precludes emission from the emissive level. These species represent significant improvements over existing dyes, and the nonpower law blinking kinetics suggest that these very small species may be alternatives to much larger and strongly intermittent semiconductor quantum dots.
Analyzing the control of mosquito-borne diseases by a dominant lethal genetic system
Authors: Atkinson Michael P. , Su Zheng , Alphey Nina , Alphey Luke S. , Coleman Paul G. , Wein Lawrence M.
Published: May 2007

Motivated by the failure of current methods to control dengue fever, we formulate a mathematical model to assess the impact on the spread of a mosquito-borne viral disease of a strategy that releases adult male insects homozygous for a dominant, repressible, lethal genetic trait. A dynamic model for the female adult mosquito population, which incorporates the competition for female mating between released mosquitoes and wild mosquitoes, density-dependent competition during the larval stage, and realization of the lethal trait either before or after the larval stage, is embedded into a susceptible–exposed–infectious–susceptible human-vector epidemic model for the spread of the disease. For the special case in which the number of released mosquitoes is maintained in a fixed proportion to the number of adult female mosquitoes at each point in time, we derive mathematical formulas for the disease eradication condition and the approximate number of released mosquitoes necessary for eradication. Numerical results using data for dengue fever suggest that the proportional policy outperforms a release policy in which the released mosquito population is held constant, and that eradication in ≈1 year is feasible for affected human populations on the order of 105to 106, although the logistical considerations are daunting. We also construct a policy that achieves an exponential decay in the female mosquito population; this policy releases approximately the same number of mosquitoes as the proportional policy but achieves eradication nearly twice as fast.
Global and regional drivers of accelerating CO
2
emissions
Authors: Raupach Michael R. , Marland Gregg , Ciais Philippe , Le Quéré Corinne , Canadell Josep G. , Klepper Gernot , Field Christopher B.
Published: May 2007

CO
2
emissions from fossil-fuel burning and industrial processes have been accelerating at a global scale, with their growth rate increasing from 1.1% y
−1
for 1990–1999 to >3% y
−1
for 2000–2004. The emissions growth rate since 2000 was greater than for the most fossil-fuel intensive of the Intergovernmental Panel on Climate Change emissions scenarios developed in the late 1990s. Global emissions growth since 2000 was driven by a cessation or reversal of earlier declining trends in the energy intensity of gross domestic product (GDP) (energy/GDP) and the carbon intensity of energy (emissions/energy), coupled with continuing increases in population and per-capita GDP. Nearly constant or slightly increasing trends in the carbon intensity of energy have been recently observed in both developed and developing regions. No region is decarbonizing its energy supply. The growth rate in emissions is strongest in rapidly developing economies, particularly China. Together, the developing and least-developed economies (forming 80% of the world's population) accounted for 73% of global emissions growth in 2004 but only 41% of global emissions and only 23% of global cumulative emissions since the mid-18th century. The results have implications for global equity.
Sildenafil accelerates reentrainment of circadian rhythms after advancing light schedules
Authors: Agostino Patricia V. , Plano Santiago A. , Golombek Diego A.
Published: May 2007

Mammalian circadian rhythms are generated by a master clock located in the suprachiasmatic nuclei and entrained by light-activated signaling pathways. In hamsters, the mechanism responsible for light-induced phase advances involves the activation of guanylyl cyclase, cGMP and its related kinase (PKG). It is not completely known whether interference with this pathway affects entrainment of the clock, including adaptation to changing light schedules. Here we report that cGMP-specific phosphodiesterase 5 is present in the hamster suprachiasmatic nuclei, and administration of the inhibitor sildenafil (3.5 mg/kg, i.p.) enhances circadian responses to light and decreases the amount of time necessary for reentrainment after phase advances of the light–dark cycle. These results suggest that sildenafil may be useful for treatment of circadian adaptation to environmental changes, including transmeridian eastbound flight schedules.
An early infructescenceHyrcantha decussata(comb. nov.) from the Yixian Formation in northeastern China
Authors: Dilcher David L. , Sun Ge , Ji Qiang , Li Hongqi
Published: May 2007

The continuing study of early angiosperms from the Yixian Formation (≈125 Ma) of northeastern China has yielded a second early angiosperm genus. This report is a detailed account of this early flowering plant and recognizes earlier reports of similar fossils from Russia and China. Entire plants, including roots, stems, and branches terminating in fruits are presented and reconstructed. Evidence for a possible aquatic nature of this plant is presented. The relationship ofHyrcantha(“Sinocarpus”) to the eudicots is discussed. The presence of this second early angiosperm genus, now known as a whole plant, is important in the discussion of its systematics and the ecology of the earliest angiosperms.
Underdetermination and Theory Succession from the Perspective of String Theory
Authors: Dawid Richard
Published: May 2007

This article investigates the implications of string theory for the conception of scientific theory confirmation. The classical understanding of theory confirmation is based on the assumption that scientific theory building is underdetermined by the available empirical data. Several arguments are presented, which suggest a devaluation of this ‘principle of scientific underdetermination’ in the context of string theory. An altered conception of scientific progress emerges that is not based on the notion of theory succession.
The Empirical Nonequivalence of Genic and Genotypic Models of Selection: A (Decisive) Refutation of Genic Selectionism and Pluralistic Genic Selectionism
Authors: Brandon Robert N. , Nijhout H. Frederik
Published: May 2007

Genic selectionists (Williams 1966; Dawkins 1976) defend the view that genes are the (unique) units of selection and that all evolutionary events can be adequately represented at the genic level. Pluralistic genic selectionists (Sterelny and Kitcher 1988; Waters 1991; Dawkins 1982) defend the weaker view that in many cases there are multiple equally adequate accounts of evolutionary events, but that always among the set of equally adequate representations will be one at the genic level. We describe a range of cases all involving stable equilibria actively maintained by selection. In these cases genotypic models correctly show that selection is active at the equilibrium point. In contrast, the genic models have selection disappearing at equilibrium. For deterministic models this difference makes no difference. However, once drift is added in, the two sets of models diverge in their predicted evolutionary trajectories. Thus, contrary to received wisdom on this matter, the two sets of models are not empirically equivalent. Moreover, the genic models get the facts wrong.
On complemented versions of James’s distortion theorems
Authors: Johnson William , Randrianantoanina Narcisse
Published: May 2007

Examples are given to show that two natural questions asked in Dowling, Randrianantoanina, and Turett, 1999, about complemented versions of James’s distortion theorems have negative answers.
Geometric angle structures on triangulated surfaces
Authors: Guo Ren
Published: May 2007

In this paper we characterize the edge invariant and Delaunay invariant of a spherical angle structure on a triangulated surface. We also characterize the edge invariant of a hyperbolic angle structure on a triangulated surface.
Character sums over shifted smooth numbers
Authors: Shparlinski Igor
Published: May 2007

We give nontrivial bounds in various ranges for character sums of the form
\[

∑

n
∈

S

(
x
,
y
)

χ
(
n
+
a
)
,

gcd
(
a
,
p
)
=
1
,

\sum _{n\in \mathcal S(x,y)}\chi (n +a), \qquad \gcd (a,p) = 1,

\]
where

χ
\chi

is a nontrivial multiplicative character modulo a prime

p
p

and

S

(
x
,
y
)

\mathcal S(x,y)

is the set of positive integers

n
≤
x

n\le x

that are divisible only by primes

q
≤
y

q \le y

.
Banach-Stone theorem for Banach lattice valued continuous functions
Authors: Ercan Z. , Önal S.
Published: May 2007

Let

X
X

and

Y
Y

be compact Hausdorff spaces,

E
E

be a Banach lattice and

F
F

be an AM space with unit. Let

π

:
C
(
X
,
E
)
→
C
(
Y
,
F
)

{\pi }:C(X,E)\rightarrow C(Y,F)

be a Riesz isomorphism such that

0
∉
f
(
X
)

0\not \in f(X)

if and only if

0
∉

π

(
f
)
(
Y
)

0\not \in {\pi }(f)(Y)

for each

f
∈
C
(
X
,
E
)

f\in C(X,E)

. We prove that

X
X

is homeomorphic to

Y
Y

and

E
E

is Riesz isomorphic to

F
F

. This generalizes some known results.
Equilibrium points of logarithmic potentials on convex domains
Authors: Langley J.
Published: May 2007

Let

D
D

be a convex domain in

C

\mathbb {C}

. Let

a
k

>
0

a_k > 0

be summable constants and let

z
k

∈
D

z_k \in D

. If the

z
k

z_k

converge sufficiently rapidly to

ζ
∈
∂
D

\zeta \in \partial D

from within an appropriate Stolz angle, then the function

∑

k
=
1

∞

a
k

/

(
z
−

z
k

)

\sum _{k=1}^\infty a_k /( z - z_k )

has infinitely many zeros in

D
D

. An example shows that the hypotheses on the

z
k

z_k

are not redundant and that two recently advanced conjectures are false.
The atomic decomposition in 𝐿¹(𝑅ⁿ)
Authors: Abu-Shammala Wael , Torchinsky Alberto
Published: May 2007

In this paper we present an atomic decomposition of integrable functions. As an application we compute the distance of

f
f

in

L

1

(

R
n

)

L^{1}(R^n)

to the Hardy space

H
1

(

R
n

)

H^1(R^n)

.
Perturbations and Weyl’s theorem
Authors: Duggal B.
Published: May 2007

A Banach space operator

T
T

is completely hereditarily normaloid,

T
∈

C
H
N

T\in \mathcal {CHN}

, if either every part, and (also)

T
p

−
1

T_p^{-1}

for every invertible part

T
p

T_p

, of

T
T

is normaloid or if for every complex number

λ
\lambda

every part of

T
−
λ
I

T-\lambda I

is normaloid. Sufficient conditions for the perturbation

T
+
A

T+A

of

T
∈

C
H
N

T\in \mathcal {CHN}

by an algebraic operator

A
A

to satisfy Weyl’s theorem are proved. Our sufficient conditions lead us to the conclusion that the conjugate operator

(
T
+
A

)
∗

(T+A)^*

satisfies

a
a

-Weyl’s theorem.
A “deformation estimate" for the Toeplitz operators on harmonic Bergman spaces
Authors: Liu Congwen
Published: May 2007

Let

B
B

denote the open unit ball in

R

n

\mathbb R^n

for

n
≥
2

n\geq 2

and

d
x

dx

the Lebesgue volume measure on

R

n

\mathbb R^n

. For

α
>
−
1

\alpha >-1

, the (weighted) harmonic Bergman space

b

2
,
α

(
B
)

b^{2,\alpha }(B)

is the space of all harmonic functions

u
u

which are in

L
2

(
B
,
(
1
−

|

x

|

2

)

α

d
x
)

L^2(B,(1-|x|^2)^{\alpha }dx)

. For

f
∈

L

∞

(
B
)

f\in L^{\infty }(B)

, the Toeplitz operator

T
f

(
α
)

T_f^{(\alpha )}

is defined on

b

2
,
α

(
B
)

b^{2,\alpha }(B)

by

T
f

(
α
)

u
=

Q

α

[
f
u
]

T_f^{(\alpha )}u = Q_{\alpha }[fu]

, where

Q

α

Q_{\alpha }

is the orthogonal projection of

L
2

(
B
,
(
1
−

|

x

|

2

)

α

d
x
)

L^2(B,(1-|x|^2)^{\alpha }dx)

onto

b

2
,
α

(
B
)

b^{2,\alpha }(B)

. In this note, we prove that for

f
∈
C
(
B
)
∩

L

∞

(
B
)

f\in C(B)\cap L^{\infty }(B)

radial,
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="limit Underscript alpha right-arrow normal infinity Endscripts double-vertical-bar upper T Subscript f Superscript left-parenthesis alpha right-parenthesis Baseline double-vertical-bar equals double-vertical-bar f double-vertical-bar Subscript normal infinity">

lim

α
→
∞

‖

T
f

(
α
)

‖
=
‖
f

‖

∞

\lim _{\alpha \to \infty } \|T_f^{(\alpha )}\|=\|f\|_{\infty }

.
A smooth counterexample to Nori’s conjecture on the fundamental group scheme
Authors: Pauly Christian
Published: May 2007

We show that Nori’s fundamental group scheme

π
(
X
,
x
)

\pi (X,x)

does not base change correctly under extension of the base field for certain smooth projective ordinary curves

X
X

of genus

2
2

defined over a field of characteristic

2
2

.
On a nonhomogeneous quasilinear eigenvalue problem in Sobolev spaces with variable exponent
Authors: Mihăilescu Mihai , Rădulescu Vicenţiu
Published: May 2007

We consider the nonlinear eigenvalue problem
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="minus div left-parenthesis StartAbsoluteValue nabla u EndAbsoluteValue Superscript p left-parenthesis x right-parenthesis minus 2 Baseline nabla u right-parenthesis equals lamda StartAbsoluteValue u EndAbsoluteValue Superscript q left-parenthesis x right-parenthesis minus 2 Baseline u">

−

div

(

|

∇
u

|

p
(
x
)
−
2

∇
u
)

=
λ

|

u

|

q
(
x
)
−
2

u

-\textrm {div}\left (|\nabla u|^{p(x)-2}\nabla u\right )=\lambda |u|^{q(x)-2}u

\]
in

Ω
\Omega

,

u
=
0

u=0

on

∂
Ω

\partial \Omega

, where

Ω
\Omega

is a bounded open set in

R

N

\mathbb R^N

with smooth boundary and

p
p

,

q
q

are continuous functions on

Ω
¯

\overline \Omega

such that

1
>

inf
Ω

q
>

inf
Ω

p
>

sup
Ω

q

1>\inf _\Omega q> \inf _\Omega p>\sup _\Omega q

,

sup
Ω

p
>
N

\sup _\Omega p>N

, and

q
(
x
)
>
N
p
(
x
)

/

(
N
−
p
(
x
)
)

q(x)>Np(x)/\left (N-p(x)\right )

for all

x
∈

Ω
¯

x\in \overline \Omega

. The main result of this paper establishes that any

λ
>
0

\lambda >0

sufficiently small is an eigenvalue of the above nonhomogeneous quasilinear problem. The proof relies on simple variational arguments based on Ekeland’s variational principle.
Mapping properties of analytic functions on the disk
Authors: Poggi-Corradini Pietro
Published: May 2007

There is a universal constant

0
>

r
0

>
1

0>r_0>1

with the following property. Suppose that

f
f

is an analytic function on the unit disk

D

\mathbb D

, and suppose that there exists a constant

M
>
0

M>0

so that the Euclidean area, counting multiplicity, of the portion of

f
(

D

)

f(\mathbb D)

which lies over the disk

D
(
f
(
0
)
,
M
)

D(f(0),M)

, centered at

f
(
0
)

f(0)

and of radius

M
M

, is strictly less than the area of

D
(
f
(
0
)
,
M
)

D(f(0),M)

. Then

f
f

must send

r
0

D

¯

r_0\overline {\mathbb D}

into

D
(
f
(
0
)
,
M
)

D(f(0),M)

. This answers a conjecture of Don Marshall.
Order-weakly compact operators from vector-valued function spaces to Banach spaces
Authors: Nowak Marian
Published: May 2007

Let 𝐸

be an ideal of 𝐿⁰

over a  𝜎

-finite measure space (Ω,Σ,𝜇)

, and let 𝐸^{∼}

stand for the order dual of 𝐸

. For a real Banach space (𝑋,|⋅|_{_{𝑋}})

let 𝐸(𝑋)

be a subspace of the space 𝐿⁰(𝑋)

of 𝜇

-equivalence classes of strongly Σ

-measurable functions 𝑓:Ω⟶𝑋

and consisting of all those 𝑓∈𝐿⁰(𝑋)

for which the scalar function |𝑓(⋅)|_{_{𝑋}}

belongs to 𝐸

. For a real Banach space (𝑌,|⋅|_{_{𝑌}})

a linear operator 𝑇:𝐸(𝑋)⟶𝑌

is said to be order-weakly compact whenever for each 𝑢∈𝐸⁺

the set
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper T left-parenthesis StartSet f element-of upper E left-parenthesis upper X right-parenthesis colon double-vertical-bar f left-parenthesis dot right-parenthesis double-vertical-bar Subscript Sub Subscript upper X Subscript Baseline less-than-or-equal-to u EndSet right-parenthesis">

T
(
{
f
∈
E
(
X
)
:

‖
f
(
⋅
)

‖

X

≤
u
}
)

\,T(\{f\in E(X):\; \|f(\cdot )\|_{_X}\le u\})\,

is relatively weakly compact in 𝑌

. In this paper we examine order-weakly compact operators 𝑇:𝐸(𝑋)⟶𝑌

. We give a characterization of an order-weakly compact operator 𝑇

in terms of the continuity of the conjugate operator of 𝑇

with respect to some weak topologies. It is shown that if (𝐸,|⋅|_{_{𝐸}})

is an order continuous Banach function space, 𝑋

is a Banach space containing no isomorphic copy of 𝑙¹

and 𝑌

is a weakly sequentially complete Banach space, then every continuous linear operator 𝑇:𝐸(𝑋)⟶𝑌

is order-weakly compact. Moreover, it is proved that if (𝐸,|⋅|_{_{𝐸}})

is a Banach function space, then for every Banach space 𝑌

any continuous linear operator 𝑇:𝐸(𝑋)⟶𝑌

is order-weakly compact iff the norm |⋅|_{_{𝐸}}

is order continuous and 𝑋

is reflexive. In particular, for every Banach space 𝑌

any continuous linear operator 𝑇:𝐿¹(𝑋)⟶𝑌

is order-weakly compact iff 𝑋

is reflexive.
Failure of separation by quasi-homomorphisms in mapping class groups
Authors: Endo H. , Kotschick D.
Published: May 2007

We show that mapping class groups of surfaces of genus at least two contain elements of infinite order that are not conjugate to their inverses, but whose powers have bounded torsion lengths. In particular every homogeneous quasi-homomorphism vanishes on such an element, showing that elements of infinite order not conjugate to their inverses cannot be separated by quasi-homomorphisms.
A strengthening of the Carleman-Hardy-Pólya inequality
Authors: Holland Finbarr
Published: May 2007

As a consequence of a more general statement proved in the paper, it is deduced that, if

n
≥
1

n\ge 1

, and

a
j

>
0
,

j
=
1
,
2
,
…
,
n

a_j>0,\,j=1,2,\dotsc ,n

, then
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="left-parenthesis StartFraction sigma-summation Underscript j equals 1 Overscript n Endscripts RootIndex j StartRoot a 1 a 2 midline-horizontal-ellipsis a Subscript j Baseline EndRoot Over sigma-summation Underscript j equals 1 Overscript n Endscripts a Subscript j Baseline EndFraction right-parenthesis Superscript 1 slash n Baseline plus StartFraction RootIndex n StartRoot a 1 a 2 midline-horizontal-ellipsis a Subscript n Baseline EndRoot Over sigma-summation Underscript j equals 1 Overscript n Endscripts RootIndex j StartRoot a 1 a 2 midline-horizontal-ellipsis a Subscript j Baseline EndRoot EndFraction less-than-or-equal-to StartFraction n plus 1 Over n EndFraction comma">

(

∑

j
=
1

n

a
1

a
2

⋯

a
j

j

∑

j
=
1

n

a
j

)

1

/

n

+

a
1

a
2

⋯

a
n

n

∑

j
=
1

n

a
1

a
2

⋯

a
j

j

≤

n
+
1

n

,

\left (\frac {\sum _{j=1}^n \root j\of {a_1a_2\dotsm a_j}}{\sum _{j=1}^n a_j}\right )^{1/n}+\frac {\root n\of {a_1a_2\dotsm a_n}}{\sum _{j=1}^n \root j\of {a_1a_2\dotsm a_j}}\le \frac {n+1}n,

\]
with equality if and only if

a
1

=

a
2

=
⋯
=

a
n

a_1=a_2=\dotsb =a_n

. This is a new refinement of Carleman’s classic inequality.
On quasifree profinite groups
Authors: Ribes Luis , Stevenson Katherine , Zalesskii Pavel
Published: May 2007

Recently, it has been shown by Harbater and Stevenson that a profinite group

G
G

is free profinite of infinite rank

m
m

if and only if

G
G

is projective and

m
m

-quasifree. The latter condition requires the existence of

m
m

distinct solutions to certain embedding problems for

G
G

. In this paper we provide several new non-trivial examples of

m
m

-quasifree groups, projective and non-projective. Our main result is that open subgroups of

m
m

-quasifree groups are

m
m

-quasifree.
Strong convergence of path for continuous pseudo-contractive mappings
Authors: Morales Claudio
Published: May 2007

The purpose of this paper is to study the convergence of a path that begins at the unique fixed point of a strongly pseudo-contractive operator defined on a closed and convex subset of a reflexive Banach space and converges to a fixed point of a pseudo-contractive mapping. Primarily, it is proven that a convex combination of these two operators is indeed strongly pseudo-contractive under the weakly inward condition. This fact generalizes a result of Barbu for accretive operators.
Unprovability of sharp versions of Friedman’s sine-principle
Authors: Bovykin Andrey
Published: May 2007

For every

n
≥
1

n\geq 1

and every function

F
F

of one argument, we introduce the statement

S
P

F
n

\mathrm {SP}_F^n

: “for all

m
m

, there is

N
N

such that for any set

A
=
{

a
1

,

a
2

,
…
,

a
N

}

A=\{a_1, a_2, \ldots , a_N\}

of rational numbers, there is

H
⊆
A

H\subseteq A

of size

m
m

such that for any two

n
n

-element subsets

a

i
1

>

a

i
2

>
⋯
>

a

i
n

a_{i_1}> a_{i_2}>\cdots > a_{i_n}

and

a

i
1

>

a

k
2

>
⋯
>

a

k
n

a_{i_1}> a_{k_2}> \cdots > a_{k_n}

in

H
H

, we have
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="StartAbsoluteValue sine left-parenthesis a Subscript i 1 Baseline dot a Subscript i 2 Baseline midline-horizontal-ellipsis a Subscript i Sub Subscript n Subscript Baseline right-parenthesis minus sine left-parenthesis a Subscript i 1 Baseline dot a Subscript k 2 Baseline midline-horizontal-ellipsis a Subscript k Sub Subscript n Subscript Baseline right-parenthesis EndAbsoluteValue greater-than upper F left-parenthesis i 1 right-parenthesis quotation-mark period">

|

sin
⁡
(

a

i
1

⋅

a

i
2

⋯

a

i
n

)
−
sin
⁡
(

a

i
1

⋅

a

k
2

⋯

a

k
n

)

|

>
F
(

i
1

)
"
.

|\sin (a_{i_1}\cdot a_{i_2} \cdots a_{i_n}) - \sin (a_{i_1}\cdot a_{k_2} \cdots a_{k_n} )|> F(i_1)".

\]
We prove that for

n
≥
2

n\geq 2

and any function

F
(
x
)

F(x)

eventually dominated by

(

2
3

)

log

(
n
−
1
)

⁡
(
x
)

({2 \over 3})^{\log ^{(n-1)}(x)}

, the principle

S
P

F

n
+
1

\mathrm {SP}_F^{n+1}

is not provable in

I

Σ
n

I\Sigma _n

. In particular, the statement

∀
n

S
P

(

2
3

)

log

(
n
−
1
)

n

\forall n \mathrm {SP}_{({2 \over 3})^{\log ^{(n-1)}}}^n

is not provable in Peano Arithmetic. In dimension 2, the result is:

I

Σ
1

I\Sigma _1

does not prove

S
P

F
2

\mathrm {SP}^2_F

, where

F
(
x
)
=
(

2
3

)

x

A

−
1

(
x
)

F(x)=({2 \over 3})^{\sqrt [A^{-1}(x)]{x}}

and

A

−
1

A^{-1}

is the inverse of the Ackermann function.