bluuebunny/crossref_metadata_2025 huggingface dataset:
Climate change and disturbance interactions
Authors: McKenzie Don , Allen Craig D.
Published: June 2007

Warming temperatures across western North America, coupled with increased drought, are expected to exacerbate disturbance regimes, particularly wildfires, insect outbreaks, and invasions of exotic species. Many ecologists and resource managers expect ecosystems to change more rapidly from disturbance effects than from the effects of a changing climate by itself. A particular challenge is to understand the interactions among disturbance regimes; for example, how will massive outbreaks of bark beetles, which kill drought‐stressed trees by feeding on cambial tissues, increase the potential for large severe wildfires in a warming climate?

Researchers in climatology, ecosystem science, fire and insect ecology, and landscape modeling from across western North America convened in Tucson, Ariz., for a 2 and a half day intensive workshop to identify new research directions in climate change and disturbance ecology. Four work groups focused on different aspects of the response of disturbance regimes to climate change: (1) extreme events and climatic variability (2) the effects of changing disturbance regimes on ecosystems, (3) disturbance interactions and cumulative effects, and (4) developing new landscape disturbance models. The workshop was structured with the analytic hierarchy process, a decisionsupport method for achieving consensus from diverse groups of experts without sacrificing individual contributions.
The continuing environmental threat of nuclear weapons: Integrated policy responses
Authors: Robock Alan , Toon Owen B. , Turco Richard P. , Oman Luke , Stenchikov Georgiy L. , Bardeen Charles
Published: June 2007

Humans have come to the realization that pollution of the atmosphere with gases and particles in the past 50 years is the dominant cause of atmospheric change [Intergovernmental Panel on Climate Change, 2007]. While land‐use change can produce large regional effects, ozone depletion, global warming, and nuclear smoke all are humandriven problems that have actual or potential global adverse impacts on our fragile environment, each with severe consequences for humanity. These effects were, or would be, inadvertent and unplanned consequences of normal daily activities, the defense policies of many nations, and nuclear proliferation. Thus, we must seek ways of continuing our normal lives while protecting ourselves from environmental catastrophe.
Law of the sea, the continental shelf, and marine research
Authors: Hutchinson Deborah R. , Rowland Robert W.
Published: June 2007

The question of the amount of seabed to which a coastal nation is entitled is addressed in the United Nations Convention on the Law of the Sea (UNCLOS). This treaty, ratified by 153 nations and in force since 1994, specifies national obligations, rights, and jurisdiction in the oceans, and it allows nations a continental shelf out to at least 200 nautical miles or to a maritime boundary. Article 76 (A76) of the convention enables coastal nations to establish their continental shelves beyond 200 nautical miles and therefore to control, among other things, access for scientific research and the use of seabed resources that would otherwise be considered to lie beyond national jurisdiction.

To date, seven submissions for extended continental shelves (ECS) have been filed under UNCLOS (Table 1). These submissions have begun to define the ambiguities in A76. How these ambiguities are resolved into final ECS boundaries will probably set important precedents guiding the future delimitation of the ECS by the United States, which has not ratified the convention, and other coastal nations. This report uses examples from the first three submissions—by the Russian Federation, Brazil, and Australia—to identify outstanding issues encountered in applying A76 to ECS delimitation.
New data set of onset of annual snowmelt on Antarctic sea ice
Authors: Willmes Sascha , Bareiss Jörg , Haas Christian
Published: June 2007

The annual onset of snowmelt on sea ice is essential for climate monitoring since it triggers a decrease in surface albedo that feeds back into a stronger absorption of shortwave radiation—a process known as the snowmelt‐albedo feedback—and thus strongly modifies the surface energy balance during summer [Curry et al., 1995]. Algorithms designed for the detection of snowmelt on Arctic sea ice and based on longterm passive‐microwave data [Anderson, 1997; Drobot and Anderson, 2001] revealed the melt season in the Arctic from 1979 to 1998 to be significantly elongated and the onset of melt to be shifted toward earlier dates [Drobot and Anderson, 2001; Belchansky et al., 2004].

In the Antarctic, however, little effort has been made so far in detecting the length of the summer melt season on sea ice by means of satellite microwave data. This results from the fact that surface melting in the Antarctic differs significantly from corresponding processes in the Arctic [Nicolaus et al., 2006]. The hemispheric differences are supported by extensive field measurements [Massom et al., 2001; Haas et al., 2001 ] and find expression in a reversal of the general surface radar backscatter and brightness temperature (TB) tendencies during summer [Haas, 2001; Kern and Heygster, 2001] : In the Antarctic, sea ice backscatter increases and TB decreases when summer approaches, contrary to the Arctic. Hence, algorithms developed for Arctic sea ice are not applicable on its southern counterpart. As summer air temperatures in the Antarctic rarely rise above 0°C, classical surface melt ponds have never been observed to the extent they appear in the Arctic and the sea ice surface typically remains snow‐covered year‐round. Drinkwater and Liu [2000] investigate snowmelt on Antarctic sea ice based on a method that identifies a decrease in surface radar backscatter. However, they detect melt to be lasting for only some days and exclusively on first‐year ice. Presumably, the backscatter decrease they observe is due to flooding of the snow before the ice underneath finally deteriorates.
Report predicts 57% growth in world energy use by 2030
Authors: Zielinski Sarah
Published: June 2007

Energy demand is expected to grow rapidly in the next decades, with world energy use rising by 57% by 2030, compared with 2004 levels, according to a new report from the U.S. Energy Information Administration. Much of this growth is expected outside of developed countries within the Organization for Economic Cooperation and Development; these non‐OECD countries will account for about 95% of the projected growth. Although rising oil prices are expected to dampen growth in this sector, their consumption is expected to reach 118 million barrels per day in 2030, 35 million barrels per day more than in 2004. Overall nuclear energy capacity will rise from 368 gigawatts in 2004 to 481 gigawatts in 2030, but declines are projected in several European countries that are planning to phase out the use of nuclear power.
Workshop establishes the Northeastern Soil Monitoring Cooperative
Authors: Lawrence Gregory B. , Bailey Scott W.
Published: June 2007

Environmental monitoring is an essential tool for identifying changes in the biosphere. The need for environmental data has led to national programs to monitor atmospheric deposition, the composition and growth of forests, and the chemistry of lakes and streams in regions affected by acidic deposition. However, there has been no organized effort to monitor changes in soils despite their importance to agriculture, forests, wetlands, and water quality.

The lack of attention given to soil monitoring can be attributed, in part, to questions regarding its feasibility Do soil changes occur too slowly to warrant monitoring, or is spatial variability too great to detect change? Within the past 15 years, however, changes in soil chemistry have been measured through repeated sampling in eastern North America and in Europe in a variety of soil types, over sampling intervals as short as 5 years. As the number of studies grows, so too does the recognition that methods of sampling and analysis are not always compatible and methods for archiving are not well developed.
Formation, dynamics, and impact of plasmaspheric plumes
Authors: Goldstein Jerry , Borovsky Joseph , Foster John , Carpenter Donald
Published: June 2007

Workshop on Plasmaspheric Drainage Plumes, Taos, New Mexico, 9–13 October 2006

Plasmaspheric plumes result from erosion of the plasmasphere. The Institute of Geophysics and Planetary Physics (IGPP) Workshop on Plasmaspheric Drainage Plumes was convened in Taos, N. M., on 9–13 October 2006 to examine outstanding questions about the formation and dynamics of plumes, and the impact of plumes on the near‐Earth space environment (geospace). A second workshop on plasmaspheric drainage plumes is planned for late 2007.
Comment on “Preseismic Lithosphere‐Atmosphere‐Ionosphere Coupling”
Authors: Rodger Craig J. , Clilverd Mark A.
Published: June 2007

The enormous economic and social disruption caused by large earthquakes drives many researchers toward the goal of better seismic understanding, with the hope of improving the forecasting of destructive events. A 2006 Eos article describes preseismic “lithosphere‐atmosphere‐ionosphere coupling” [Kamogawa, 2006], giving the strong impression that the ionospheric signatures could indeed be used to provide early warning of imminent shocks. On the basis of the literature discussed in the article, this would indeed be true.

In many of the cases outlined, however, the high correlations described occur in small case studies, and no mention is made of follow‐on statistical studies that have drawn totally opposite conclusions, i.e., that the proposed coupling does not exist. Two clear examples come from the description of earthquake precursors reported in the propagation behavior of very low frequency (VLF) electromagnetic waves beneath the lower ionosphere.
Measuring global oceans and terrestrial freshwater from space
Authors: Alsdorf Doug , Fu Lee‐Lueng , Mognard Nelly , Cazenave Anny , Rodriguez Ernesto , Chelton Dudley , Lettenmaier Dennis
Published: June 2007

Radar altimetry has revolutionized oceanography by providing global measurements of ocean surface topography (OST [e.g., Fu and Cazenave, 2001]). Long‐term measurements of large‐scale circulation and heat storage of the global oceans have led to discoveries such as the effects of changes in ocean circulation on climate (e.g., El Niño and La Niña). A critical limitation, however, is the 200‐ to 300‐kilometer spacings between satellite orbital tracks, which are unable to resolve the currents and oceanic mesoscale processes that contain 90% of the kinetic energy of the oceans.

In contrast to ocean observations, surface freshwater measurements are limited mostly to in situ networks of gauges that record water surface elevations at fixed points along river channels. Globally, the spatial and temporal distribution of water stored on the land surface and moving through river channels is known only crudely. Furthermore, water movement in wetlands and across floodplains throughout the world is essentially unmeasured, significantly limiting our understanding of flood processes.
Investigators share improved understanding of the North American Carbon Cycle
Authors: Birdsey Richard A. , Cook Robert , Denning Scott , Griffith Peter , Law Beverly , Masek Jeffrey , Michalak Anna , Ogle Stephen , Ojima Dennis , Pan Yude , Sabin Christopher , Sheffner Edwin , Sundquist Eric
Published: June 2007

The U.S. North American Carbon Program (NACP) sponsored an “all‐scientist” meeting to review progress in understanding the dynamics of the carbon cycle of North America and adjacent oceans, and to chart a course for improved integration across scientific disciplines, scales, and Earth system boundaries. The meeting participants also addressed the need for better decision support tools for managing the carbon cycle of North America, so that strong science can inform policy as interest in taking action increases across the nation.

Herein we report on themes to integrate the diversity of NACP science and fill significant gaps for understanding and managing the North American carbon cycle: integration among disciplines involving land, atmosphere, and ocean research; strengthening data management infrastructure to support modeling and analysis; identification of study regions that are critical for reducing uncertainties in the North American carbon balance; and integrating biophysical science with the human dimensions of carbon management and decision support.
[Comment on “Exaggerated claims about earthquake predictions: Analysis of NASA's method”] Pattern informatics and cellular seismology: A comparison of methods
Authors: Rundle John B. , Tiampo Kristy F. , Klein William
Published: June 2007

The recent article in Eos by Kafka and Ebel [2007] is a criticism of a NASA press release issued on 4 October 2004 describing an earthquake forecast (http://quakesim.jpl.nasa.gov/scorecard.html) based on a pattern informatics (PI) method [Rundle et al., 2002]. This 2002 forecast was a map indicating the probable locations of earthquakes having magnitude m>5.0 that would occur over the period of 1 January 2000 to 31 December 2009. Kafka and Ebel [2007] compare the Rundle et al. [2002] forecast to a retrospective analysis using a cellular seismology (CS) method. Here we analyze the performance of the Rundle et al. [2002] forecast using the first 15 of the m>5.0 earthquakes that occurred in the area covered by the forecasts.
Correction [to “Next solar cycle expected to be intense”]
Authors: Anonymous
Published: June 2007

A misleading article by NOAA led Eos to incorrectly report the results of the April meeting of the agency' Solar Cycle 24 Prediction Panel in its 8 May issue (Eos, 88 (19), 2007). During the meeting, half the panelists predicted a moderately strong cycle of 140±20 sunspots, with a peak in October 2011, and the other half predicted a moderately weak cycle of 90±10 sunspots, with a peak in August 2012.
Economic impacts of rapid glacier retreat in the Andes
Authors: Vergara Walter , Deeb Alejandro , Valencia Adriana , Bradley Raymond , Francou Bernard , Zarzar Alonso , Grünwaldt Alfred , Haeussling Seraphine
Published: June 2007

In the Andes, runoff from glacierized basins is an important element of water budgets, assuring year‐round flows for agriculture, potable water, power generation, and ecosystem integrity. Thus, changes induced by tropical glacier retreat constitute an early case of the need for adaptation and the type and size of associated economic and social impacts caused by climate change.
Magnetic anomaly map of the world
Authors: Purucker Michael E.
Published: June 2007

The Magnetic Anomaly Map of the World is the first global compilation of the wealth of magnetic anomaly information derived from more than 50 years of aeromagnetic surveys over land areas, research vessel magnetometer traverses at sea, and observations from Earth‐orbiting satellites, supplemented by anomaly values derived from oceanic crustal ages. This map will soon be published by the United Nations Educational, Scientific and Cultural Organization (UNESCO) and the Commission for the Geological Map of the World, and will be publicly released at the July 2007 meeting of the International Union of Geodesy and Geophysics, in Perugia, Italy.

Metamorphism, petrology, and redox state all have important effects on the magnetism of crustal materials. The magnetic anomalies represented on this map (Figure 1) originate primarily in igneous and metamorphic rocks, in the Earth's crust, and possibly in the uppermost mantle. Magnetic anomalies represent an estimate of the short‐wavelength (<2600 kilometer) fields associated with these parts of the Earth, after estimates of fields from other sources have been subtracted from the measured field magnitude.
Venus flyby a success; Next stop, Mercury
Authors: Zielinski Sarah
Published: June 2007

The first spacecraft to head to Mercury in more than 30 years performed its second successful flyby of Venus on 5 June, providing the first opportunity for testing all of the spacecraft's scientific instruments.

NASA's MESSENGER (Mercury Surface, Space Environment, Geochemistry, and Ranging) spacecraft left Earth in August 2004 and is expected to reach Mercury in March 2011. Along the way it has performed flybys of Earth and Venus and will perform three fly‐bys of Mercury before settling into its final orbit. These flybys provide a gravity assist for the spacecraft; the one this month changed the direction of the spacecraft's path and decelerated it from 36.5 to 27.8 kilometers per second.
New U.S. wetland protection guidance issued
Authors: Kumar Mohi
Published: June 2007

A new joint guidance intended to help field officers distinguish whether or not specific wetlands fall under federal protection will expand the amount of hydrological and ecological information collected for wetlands, according to government officials.

The guidance, issued on 5 June by the U.S. Environmental Protection Agency and the Army Corps of Engineers, should help the agencies comply with a June 2006 ruling by the U.S. Supreme Court in Rapanos v. United States and Carabell v. United States. The Court ruled against the plaintiffs, who wanted to fill in their wetlands, but was split over further details regarding how wetlands are protected under the Clean Water Act (CWA), which governs the ecological health of U.S. navigable waters. Using the justices' written opinions, the EPA and Corps adopted specific criteria to assess whether wetlands are protected under the CWA.
International Ocean Research: Common opportunities and challenges
Authors: Urban Ed
Published: June 2007

The impending interruption of important satellite observations and the need for improvements in data management and communications are of significant concerns to the ocean community.

Plans to reduce satellite observations of the ocean will negatively affect both research projects and observational programs. Progress in our understanding of how ocean physics and chemistry interact with living organisms and ecosystems in space and time will be impaired by the loss of high‐quality satellite data streams. Prompt action is needed to prevent this from happening. Satellite observation programs that are particularly imperiled and must be maintained include sea surface height, ocean color, and sea surface vector winds and waves. Likewise, the long‐term continuity of measurements of sea ice, microwave sea surface temperature, and rainfall measurements must be assured.
Use of cloud radars and radiometers for tropical cyclone intensity estimation
Authors: Wong Valerie , Emanuel Kerry
Published: June 2007

Tropical cyclone intensity is shown to be proportional to the difference between the moist static energy of the eyewall and that of the undisturbed environment, and to the difference between the absolute temperatures of the boundary layer and of the storm top. Measurements of the radial gradient of cloud top altitude and temperature from the eyewall to the outer region of the storm should therefore provide a measure of storm intensity, when coupled with an estimate of the total temperature difference between the sea surface and the cloud top. Here we develop a formalism for making such intensity estimates and apply it to cloud top heights and temperatures produced by an axisymmetric, nonhydrostatic hurricane model. The results are encouraging, and offer the potential for accurate remote detection of tropical cyclone intensity, to supplement existing satellite‐based methods.
Review: Dystroglycan in the Nervous System
Authors: Samwald Matthias
Published: June 2007

Dystroglycan is part of a large complex of proteins, the dystrophin-glycoprotein complex, which has been implicated in the pathogenesis of muscular dystrophies for a long time. Besides muscular degeneration many patients manifest symptoms of neurological and cognitive dysfunction. Newer findings suggest that dystroglycan is implicated in brain development, synapse formation and plasticity, nerve-glia interactions and maintenance of the blood-brain barrier.Most research so far has focused on the functions of dystroglycan in muscle and neuromuscular junctions, while its role in the brain and interneuronal synapses has been largely neglected. This review will give an overview of the biochemistry of dystroglycan, its interaction with other proteins as well as its confirmed and hypothetical functions in the nervous system in health and diesease.
Plant Transcription Factors @ uni-potsdam.de
Authors: Riaño-Pachón Diego Mauricio , Dreyer Ingo , Ruzicic Slobodan , Mueller-Roeber Bernd
Published: June 2007

We present the Plant Transcription Factor Database (PlnTFDB), and the putative complete set of TFs in the algae Chlamydomonas reinhardtii, Ostreococcus tauri and the vascular plants Oryza sativa and Arabidopsis thaliana.
Modulation of mast cell proteinase‐activated receptor expression and IL‐4 release by IL‐12
Authors: Zhang Huiyun , Yang Xiaoyu , Yang Haiwei , Zhang Zhongfang , Lin Qing , Zheng Yanshan , Chen Shaoying , Yang Pingchang , He Shaoheng
Published: June 2007

It has been recognized that protease‐activated receptors (PARs), interleukin (IL)‐4 and IL‐6 are involved in the pathogenesis of allergic diseases, and that IL‐12 plays a role in adaptive immune response. However, little is known of the effect of IL‐12 on protease‐induced cytokine release from mast cells. In the present study, we examined potential influence of IL‐12 on mast cell PAR expression and IL‐4 and IL‐6 release. The results showed that IL‐12 downregulated the expression of PAR‐2 and upregulated expression of PAR‐4 on P815 cells. It also downregulated expression of PAR‐2 mRNA, and upregulated expression of PAR‐1, PAR‐3 and PAR‐4 mRNAs. However, IL‐12 enhanced trypsin‐ and tryptase‐induced PAR‐2 and PAR‐2 mRNA expression. It was observed that IL‐12 induced release of IL‐4, but reduced trypsin‐ and tryptase‐stimulated IL‐4 secretion from P815 cells. PD98059, U0126 and LY294002 not only abolished IL‐12‐induced IL‐4 release but also inhibited IL‐12‐induced phosphorylation of extracellular signal‐regulated kinase and Akt. In conclusion, IL‐12 may serve as a regulator in keeping the balance of Th1 and Th2 cytokine production in allergic inflammation.
Toll‐like receptors in the gonads and reproductive tract: emerging roles in reproductive physiology and pathology
Authors: Girling Jane E , Hedger Mark P
Published: June 2007

Interactions between the immune system and reproductive system have important consequences for fertility and reproductive health in general. There is increasing evidence that many of the interactions between the immune and reproductive systems involve the Toll‐like receptors (TLRs). While there is no doubt that TLRs are important in providing protection against infection in the reproductive tract, there is increasing evidence for the involvement of TLRs in more basic pathology and physiology of reproduction. In the female, TLRs have been implicated in critical aspects of ovarian, endometrial and placental function, as well as in ovarian cancer, pelvic inflammatory disease, intrauterine growth restriction, pre‐eclampsia and preterm birth. In the male, TLRs appear to play a role in the control of testicular steroidogenesis and spermatogenesis in disease and, potentially, during normal function, as well. Recent studies also have begun to highlight the role of various TLRs in the aetiology of prostatitis and prostatic cancer. Given the nascent state of knowledge concerning this important area, it is clear that more studies are needed, which should provide valuable new insights into the biology of the TLRs and reproductive function in general.
Ferromagnetic shape memory alloys: A theoretical approach
Authors: Paul D. I. , McGehee W. , O’Handley R. C. , Richard M.
Published: June 2007

The interaction of crystallographic twin boundaries with an external magnetic field as a mechanism for shape deformation is analyzed theoretically and applied to the alloy Ni2MnGa. A defect, modeled as a Gaussian strain distribution interacting elastically with the twin boundary, is localized in one of the two variants bordering the twin boundary. Micromagnetic equations are used to determine the magnetization angles throughout the variants as well as the equilibrium positions of the twin boundary. These values of the magnetization angle are now incorporated into equations governing the time dependence of the twin boundary motion. The minimum velocity to maintain twin boundary motion in the presence of defects is determined as a function of defect strength and applied field. The results show, among others, a resistance to twin boundary motion due to lattice discreteness and a large but temporary reduction in twin boundary velocity during the interaction between the localized pulse and the defect. Finally, a distribution of stress-related defects is postulated and the relative elongation of the material as a function of the applied magnetic field is obtained. Further, experimental results on the temperature dependence of the magnetic anisotropy and magnetization, as well as the effects of random thermal fluctuations, are included in our micromagnetic equations. The upper limit to the magnetic field driving force then becomes a function of the temperature dependence of the anisotropy. We show that the random thermal energy input is critical to overcoming stress-related obstacles to twin boundary motion.
Second- and third-order triples and quadruples corrections to coupled-cluster singles and doubles in the ground and excited states
Authors: Shiozaki Toru , Hirao Kimihiko , Hirata So
Published: June 2007

Second- and third-order perturbation corrections to equation-of-motion coupled-cluster singles and doubles (EOM-CCSD) incorporating excited configurations in the space of triples [EOM-CCSD(2)T and (3)T] or in the space of triples and quadruples [EOM-CCSD(2)TQ] have been implemented. Their ground-state counterparts—third-order corrections to coupled-cluster singles and doubles (CCSD) in the space of triples [CCSD(3)T] or in the space of triples and quadruples [CCSD(3)TQ]—have also been implemented and assessed. It has been shown that a straightforward application of the Rayleigh-Schrödinger perturbation theory leads to perturbation corrections to total energies of excited states that lack the correct size dependence. Approximations have been introduced to the perturbation corrections to arrive at EOM-CCSD(2)T, (3)T, and (2)TQ that provide size-intensive excitation energies at a noniterative O(n7), O(n8), and O(n9) cost (n is the number of orbitals) and CCSD(3)T and (3)TQ size-extensive total energies at a noniterative O(n8) and O(n10) cost. All the implementations are parallel executable, applicable to open and closed shells, and take into account spin and real Abelian point-group symmetries. For excited states, they form a systematically more accurate series, CCSD<CCSD(2)T<CCSD(2)TQ<CCSD(3)T1eV) and the ground-state wave function has single-determinant character. In other cases, however, the corrections tend to overestimate the triples and quadruples effects, the origin of which is discussed. For ground states, the third-order corrections lead to a rather small improvement over the highly effective second-order corrections [CCSD(2)T and (2)TQ], which is a manifestation of the staircase convergence of perturbation series.
Three-dimensional current systems generated by plasmas colliding in a background magnetoplasma
Authors: Gekelman W. , Collette A. , Vincena S.
Published: June 2007

Results are presented from an experiment in which two plasmas, initially far denser than a background magnetoplasma, collide as they move across the magnetic field. The dense plasmas are formed when laser beams, nearly orthogonal to the background magnetic field, strike two targets. The merging plasmas are observed to carry large diamagnetic currents. A reconnection event is triggered by the collision and the electric field induced in this event generates a field-aligned current, which is the first step in the development of a fully three-dimensional current system. After several ion gyroperiods, the current systems become those of shear Alfvén waves. As local currents move, small reconnection “flares” occur at many locations throughout the volume, but they do not seem to affect the overall system dynamics. The data clearly show that the induced electric field is carried though the system by shear Alfvén waves. The wave electric fields as well as local magnetic helicity are discussed.
Optimal control simulation of the Deutsch-Jozsa algorithm in a two-dimensional double well coupled to an environment
Authors: Ndong M. , Lauvergnat D. , Chapuisat X. , Desouter-Lecomte M.
Published: June 2007

The quantum Deutsch-Jozsa algorithm is implemented by using vibrational modes of a two-dimensional double well. The laser fields realizing the different gates (NOT, CNOT, and HADAMARD) on the two-qubit space are computed by the multitarget optimal control theory. The stability of the performance index is checked by coupling the system to an environment. Firstly, the two-dimensional subspace is coupled to a small number Nb of oscillators in order to simulate intramolecular vibrational energy redistribution. The complete (2+Nb)D problem is solved by the coupled harmonic adiabatic channel method which allows including coupled modes up to Nb=5. Secondly, the computational subspace is coupled to a continuous bath of oscillators in order to simulate a confined environment expected to be favorable to achieve molecular computing, for instance, molecules confined in matrices or in a fullerene. The spectral density of the bath is approximated by an Ohmic law with a cutoff for some hundreds of cm−1. The time scale of the bath dynamics (of the order of 10fs) is then smaller than the relaxation time and the controlled dynamics (2ps) so that Markovian dissipative dynamics is used.
Diminished gradient dependence of density functionals: Constraint satisfaction and self-interaction correction
Authors: Csonka Gábor I. , Vydrov Oleg A. , Scuseria Gustavo E. , Ruzsinszky Adrienn , Perdew John P.
Published: June 2007

The Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation for the exchange-correlation energy functional has two nonempirical constructions, based on satisfaction of universal exact constraints on the hole density or on the energy. We show here that, by identifying one possible free parameter in exchange and a second in correlation, we can continue to satisfy these constraints while diminishing the gradient dependence almost to zero (i.e., almost recovering the local spin density approximation or LSDA). This points out the important role played by the Perdew-Wang 1991 nonempirical hole construction in shaping PBE and later constructions. Only the undiminished PBE is good for atoms and molecules, for reasons we present, but a somewhat diminished PBE could be useful for solids; in particular, the surface energies of solids could be improved. Even for atoms and molecules, a strongly diminished PBE works well when combined with a scaled-down self-interaction correction (although perhaps not significantly better than LSDA). This shows that the undiminished gradient dependence of PBE and related functionals works somewhat like a scaled-down self-interaction correction to LSDA.
Intersubband transitions in asymmetric AlxGa1−xN∕GaN double quantum wells
Authors: Lei S. Y. , Shen B. , Cao L. , Yang Z. J. , Zhang G. Y.
Published: June 2007

Influence of the width and Al composition of one well in asymmetric Al0.85Ga0.15N∕GaN double quantum wells (DQWs) on the absorption coefficients and the wavelengths of the intersubband transitions (ISBTs) has been investigated by solving the Schrödinger and Poisson equations self-consistently. When the well width is chosen to be 1.91nm, the three-energy-level DQWs are realized. The ISBT between the first odd order and the second even order subbands (the 1odd-2even ISBT) has comparable absorption coefficient with the 1odd-2odd ISBT. Their wavelengths are located at 1.3 and 1.54μm, respectively. When the well width is 2.77nm, the four-energy-level DQWs are realized. The 1odd-2even and the 1even-2odd ISBTs have comparable absorption coefficients. Their wavelengths are located at 1.41 and 2.54μm, respectively. The energy separation between the excited subbands is determined to have the minimum value of 144meV due to the band anticrossing interaction. The calculated results give possible application to ultrafast two-color optoelectronic devices operating within the optical communication wavelength range.
A continuum thermodynamics model for the sensing effect in ferromagnetic shape memory Ni–Mn–Ga
Authors: Sarawate N. N. , Dapino M. J.
Published: June 2007

A magnetomechanical model based on continuum thermodynamics is presented which describes the sensing effect in single-crystal ferromagnetic shape memory Ni–Mn–Ga. The model quantifies the stress and magnetization dependence on strain at different values of bias fields under isothermal conditions. A magnetic Gibbs energy is considered as the thermodynamic potential with Zeeman, magnetostatic, and anisotropy energy contributions. Constitutive equations for stress and magnetization are obtained in the isothermal case after restricting the process through the Clausius-Duhem inequality for the second law of thermodynamics. Mechanical dissipation and the microstructure of Ni–Mn–Ga are incorporated in the continuum model through the internal state variables volume fraction, domain fraction, and magnetization rotation angle. Closed-form solutions describing the evolution of the internal state variables are developed. The model requires only seven parameters identified from simple experiments: stress-strain curve at zero field, and easy-axis and hard-axis magnetization curves.
Combination of a polyaniline anode and doped charge transport layers for high-efficiency organic light emitting diodes
Authors: Fehse Karsten , Schwartz Gregor , Walzer Karsten , Leo Karl
Published: June 2007

Up to now, most organic light emitting diodes (OLEDs) have utilized inorganic materials as transport anodes. In this study, we show that conductive polymers are suitable for this purpose as well. Polyaniline anodes, with a conductivity of 200 S/cm, are used to inject holes into the adjacent organic layers. Due to electrical doping of the electron and hole transport layer with an intrinsic emission layer sandwiched in between (pin-OLED), the devices reach high luminance at low voltage. The phosphorescent emitters Ir(MDQ)2(acac) and Ir(ppy)3, as well as the fluorescent emitter Spiro-DPVBi, are implemented within pin-OLEDs using a polyaniline anode. By the use of different host materials, a green double-emitting OLED is demonstrated and compared to the corresponding single emission layer device. Furthermore, a white OLED combining fluorescent and phosphorescent emitting layers is presented, reaching 8.9 lm/W at 1000 cd∕m2. The results demonstrate an efficient charge carrier injection from the polymer into the p-type doped hole transport layer, leading to good power efficiencies of the OLEDs.
Pd–In–Fe shape memory alloy
Authors: Ishikawa H. , Sutou Y. , Omori T. , Oikawa K. , Ishida K. , Yoshikawa A. , Umetsu R. Y. , Kainuma R.
Published: June 2007

Martensitic, magnetic transformations, and crystal structures in Pd–In–Fe alloys were investigated. It was confirmed that some Pd–In–Fe alloys show martensitic transformation from a Heusler-type (L21) ordered bcc phase to a 2M-type (DO22) structure and that an almost perfect superelastic effect accompany the transformation can be obtained. Furthermore, some alloys show transformation from the paramagnetic parent phase to the ferromagnetic martensite phase.
Lateral variation of target poisoning during reactive magnetron sputtering
Authors: Güttler D. , Grötzschel R. , Möller W.
Published: June 2007

The reactive gas incorporation into a Ti sputter target has been investigated using laterally resolving ion beam analysis during dc magnetron deposition of TiN in an Ar∕N2 atmosphere. At sufficiently low reactive gas flow, the nitrogen incorporation exhibits a pronounced lateral variation, with a lower areal density in the target racetrack compared to the target center and edge. The findings are reproduced by model calculations. In the racetrack, the balance of reactive gas injection and sputter erosion is shifted toward erosion. The injection of nitrogen is dominated by combined molecular adsorption and recoil implantation versus direct ion implantation.
Nanocrystalline CdS-water-soluble conjugated-polymers: High performance photoelectrochemical cells
Authors: Lee Wonjoo , Mane Rajaram S. , Min Sun-Ki , Yoon Tae Hyun , Han Sung-Hwan , Lee Soo-Hyoung
Published: June 2007

Enhanced photoelectrochemical cell performance of nanocrystalline CdS-water-soluble conjugated-polymer sensitizers was demonstrated. The water-soluble polymers with quaternary pyridinium salts can be easily layered after dipping nanocrystalline CdS films in the aqueous polymer solution. The 2.37% energy conversion efficiency of CdS-poly(2-ethynyl-N-carboxypropylpyridiniumbromide) (LM 3) conjugated-polymer sensitizer was significantly higher than that of the bare (0.57%) and CdS-poly(2-ethynyl-N-aminopropylpyridiniumbromide) (LM 2) conjugated-polymer sensitizer (2.15%) under AM1.5 condition (80mW∕cm2).
Tunable electrical conductivity in nanoscale Gd-doped ceria thin films
Authors: Karthikeyan Annamalai , Tsuchiya Masaru , Chang Chia-Lin , Ramanathan Shriram
Published: June 2007

Nanoscale Gd-doped ceria thin films exhibit a slow change in conductivity upon high temperature (>800°C) annealing for extended period of time in controlled oxygen environments. Conductivity can be modulated reversibly upon thermochemical conditioning. The process is kinetically driven, and hence transient states can be quenched at lower temperatures. Nanoscale oxides with more than one order of difference in electrical properties can be obtained by suitable treatments. The results are of potential relevance to synthesizing oxides with controlled functional properties.
Direct observation of 90° domain switching in lead zirconate titanate thick films using x-ray diffraction
Authors: Osone Satoko , Shimojo Yoshiro , Brinkman Kyle , Iijima Takashi , Saito Keisuke
Published: June 2007

Using an x-ray diffraction with reciprocal space mapping, 90° domain switching in tetragonal lead zirconate titanate (PZT) thick films under an applied field was studied. An increase in the c-axis lattice constant and a decrease in the a-axis lattice constant due to the piezoelectric effect and switching from a domain to c domain (90° domain switching) were observed under an applied field. The contribution from 90° domain switching to the total strain was estimated to be 60%–100%, which is almost the same as that for bulk PZT. High value is consistent with the intrinsic nonlinearity in a tetragonal film.
Negative index material composed of electric and magnetic resonators
Authors: Liu Ruopeng , Degiron Aloyse , Mock Jack J. , Smith David R.
Published: June 2007

Negative index-of-refraction materials (NIMs) require both the electric permittivity and the magnetic permeability of the material to be negative. Most reported NIMs have combined conducting split ring resonators (SRRs) to realize the magnetic response and nonresonant wires to realize the electric response. Here, however, the authors demonstrate an impedance-matched, relatively broadband NIM which makes use of SRRs and electric resonators, tuned such that they resonate at the same frequency and with nearly the same frequency dispersion. The NIM properties are confirmed by direct measurements of the phase variation and field distributions, obtained by field mapping.
Voltage-tuned resonant reflectance optical filter for visible wavelengths fabricated by nanoreplica molding
Authors: Yang Fuchyi , Yen Gary , Cunningham Brian T.
Published: June 2007

A guided-mode resonant filter incorporating an electro-optically tunable liquid crystal refractive index is demonstrated at a wavelength of 655nm and a tuning range of 4nm. Rigorous coupled wave analysis and finite difference time domain analysis are used to simulate the characteristics of the filter during liquid crystal reorientation. Tuning performance is demonstrated that is consistent with the device simulations. Tunable filters in the visible wavelength range that are inexpensively fabricated over large surface areas are expected to find applications in optical limiting and video display.
Epitaxial growth and dielectric properties of Pb0.4Sr0.6TiO3 thin films on (00l)-oriented metallic Li0.3Ni0.7O2 coated MgO substrates
Authors: Li X. T. , Du P. Y. , Mak C. L. , Wong K. H.
Published: June 2007

Highly (00l)-oriented Li0.3Ni0.7O2 thin films have been fabricated on (001) MgO substrates by pulsed laser deposition. The Pb0.4Sr0.6TiO3 (PST40) thin film deposited subsequently also shows a significant (00l)-oriented texture. Both the PST40 and Li0.3Ni0.7O2 have good epitaxial behavior. The epitaxial growth of the PST40 thin film is more perfect with the Li0.3Ni0.7O2 buffer layer due to the less distortion in the film. The dielectric tunability of the PST40 thin film with Li0.3Ni0.7O2 buffer layer therefore reaches 70%, which is 75% higher than that without Li0.3Ni0.7O2 buffer layer, and the dielectric loss of the PST40 thin film is 0.06.
14
MHz
organic diodes fabricated using photolithographic processes
Authors: Ai Yuming , Gowrisanker Srinivas , Jia Huiping , Trachtenberg Isaac , Vogel Eric , Wallace Robert M. , Gnade Bruce E. , Barnett Raymond , Stiegler Harvey , Edwards Hal
Published: June 2007

Organic semiconductor-based Schottky diodes operating at 14MHz, fabricated using conventional photolithographic and etching processes, have been demonstrated. Copper phthalocyanine is the semiconductor, with gold and aluminum as the Ohmic and Schottky contacts, respectively. The organic diode based rectifier circuit generated a dc output voltage of approximately 2V at 14MHz, using an input ac signal with a zero-to-peak voltage amplitude of 5V. These devices showed little degradation under continuous ac voltage stress when operated in vacuum.
Molding light flow from photonic band gap circuits to microstructured fibers
Authors: Bauer James , John Sajeev
Published: June 2007

The authors demonstrate nearly lossless, broadband coupling of light between photonic band gap (PBG) circuits and photonic crystal fibers (PCFs) using two-dimensional design paradigms. A hollow-core PBG fiber yields a coupling efficiency of better than 94% over a bandwidth of 25% of the center frequency, with peak transmittance exceeding 98%. A small-mode-area PCF consisting of a subwavelength solid core with nonadiabatic taper, combined with a PBG beam collimator at the air-waveguide exit port, yields over 98% coupling efficiency over a bandwidth of 135nm centered at a wavelength of 1.5μm.
The role of minimum disease resistance standards for the control of cereal diseases
Authors: Wallwork Hugh
Published: June 2007

A set of Minimum Disease resistance Standards (MDS) has been developed for rust resistance in new wheat varieties in Australia. These standards aim to provide protection to growers from varieties that produce large amounts of inoculum and, more specifically, protect the usefulness of resistance genes by reducing the probability of new pathotypes evolving with virulences that can overcome them. This paper provides a historical background to the establishment of MDS in Australia, the rationale for its introduction and the appropriateness of different resistance scales, problems that have been encountered, and the way forward to fully implement MDS. A brief consideration is also given as to which other wheat and barley diseases MDS may usefully be applied to.
The situation of common wheat rusts in the Southern Cone of America and perspectives for control
Authors: Germán Silvia , Barcellos Amarilis , Chaves Marcia , Kohli Mohan , Campos Pablo , de Viedma Lidia
Published: June 2007

Approximately 9 million ha of wheat (Triticum aestivum and T. durum) is sown in the Southern Cone of America (Argentina, Brazil, Chile, Paraguay, and Uruguay). Two rust epidemiological zones separated by the Andean mountain range have been described in the region. Presently, leaf rust (caused by Puccinia triticina) is the most important rust disease of wheat. The utilisation of susceptible or moderately susceptible cultivars in a high proportion of the wheat area allows the pathogen to oversummer across large areas, resulting in early onset of the epidemics. Severe epidemics cause important economic losses if chemical control is not used. The pathogen population is extremely dynamic, leading to transitory resistance in commercial cultivars. Lr34 is commonly present in the regional germplasm, but there is limited knowledge about the presence of other genes conferring resistance in cultivars. Genes Lr28, Lr36, Lr38, Lr41, and Lr43 provide effective resistance in the region. The best strategy for the stabilisation of the pathogen population and resistance is considered to be the use of adult plant resistance conferred by minor additive genes including Lr34 and Lr46. Sources of this type of resistance from CIMMYT and the region have been made available to breeding programs in the Southern Cone. Stripe rust (P. striiformis f. sp. tritici) is endemic in Chile where chemical control is required to prevent severe losses in stripe rust susceptible cultivars. Although new virulent races emerge frequently, resistance genes Yr5, Yr8, Yr10, Yr15, and YrSp are currently effective in Chile. Some important stripe rust epidemics have occurred in Argentina, Brazil, and Uruguay. Avoiding the use of highly susceptible cultivars appears to be an effective strategy to prevent stripe rust epidemic development in this area. There have been no serious stem rust (P. graminis f. sp. tritici) epidemics for over 2 decades; the disease was controlled by resistant cultivars. The most important genes conferring resistance in Southern Cone germplasm at the present time are probably Sr24 and Sr31. Other effective genes are Sr22, Sr25, Sr26, Sr32, Sr33, Sr35, Sr39, and Sr40. Several stem rust susceptible wheat cultivars have recently been released. The increased cultivation of susceptible cultivars may lead to higher stem rust incidence, increasing the probability of appearance of new virulent races. Since the 1BL.1RS translocation possessing Sr31 is present in a high proportion of the regional germplasm, the possible introduction of stem rust with Sr31 virulence from Africa is of great concern.
Activation tagging in plants—generation of novel, gain-of-function mutations
Authors: Ayliffe Michael A. , Pryor Anthony J.
Published: June 2007

Activation tagging is a mutagenesis strategy that generates dominant, gain-of-function mutations as a consequence of gene over-expression. These mutations cause a class of mutant previously unobtainable by conventional mutagenesis. Unlike most mutant phenotypes, which are generally a consequence of gene inactivation, activation tagged phenotypes arise from excess functional gene product. Gene over-expression mutations are obtained by randomly inserting regulatory sequences throughout the genome, using either high-throughput plant transformation or mobile transposable elements to distribute these regulatory elements. Since the sequence of the regulatory element vector is known, it acts as a molecular tag, making isolation of the over-expressed gene a relatively straightforward process using standard molecular biological techniques. Activation tagged phenotypes have been generated by the over-expression of genes encoding a diverse range of protein and RNA products that are involved in all aspects of plant biogenesis. This mutation approach has been used extensively in Arabidopsis and to a lesser extent in several other species. In this review we summarise activation tagging in plants and suggest that the development of this mutagenesis strategy in more plants of agronomic significance is highly desirable.