bluuebunny/crossref_metadata_2025 huggingface dataset:
Retention time and dispersion associated with submerged aquatic canopies
Authors: Nepf H. , Ghisalberti M. , White B. , Murphy E.
Published: April 2007

The shear layer at the top of a submerged canopy generates coherent vortices that control exchange between the canopy and the overflowing water. Unlike free shear layers, the vortices in a canopy shear layer do not grow continuously downstream but reach and maintain a finite scale determined by a balance between shear production and canopy dissipation. This balance defines the length scale of vortex penetration into the canopy, δe, and the region of rapid exchange between the canopy and overflow. Deeper within the canopy, transport is constrained by smaller turbulence scales. A two‐box canopy model is proposed on the basis of the length scale δe. Using diffusivity and exchange rates defined in previous studies, the model predicts the timescale required to flush the canopy through vertical exchange over a range of canopy density and height. The predicted canopy retention times, which range from minutes to an hour, are consistent with canopy retention inferred from tracer observations in the field and comparable to retention times for some hyporheic regions. The timescale for vertical exchange, along with the in‐canopy velocity, determines the minimum canopy length for which vertical exchange dominates water renewal. Shorter canopies renew interior water through longitudinal advection. Finally, canopy water retention influences longitudinal dispersion through a transient storage process. When vertical exchange controls canopy retention, the transient storage dispersion increases with canopy height. When longitudinal advection controls water renewal, dispersion increases with canopy patch length.
Exaggerated claims about earthquake predictions
Authors: Kafka Alan L. , Ebel John E.
Published: April 2007

The perennial promise of successful earthquake prediction captures the imagination of a public hungry for certainty in an uncertain world. Yet, given the lack of any reliable method of predicting earthquakes [e.g.,Geller, 1997;Kagan and Jackson, 1996; Evans, 1997], seismologists regularly have to explain news stories of a supposedly successful earthquake prediction when it is far from clear just how successful that prediction actually was. When journalists and public relations offices report the latest ‘great discovery’ regarding the prediction of earthquakes, seismologists are left with the much less glamorous task of explaining to the public the gap between the claimed success and the sober reality that there is no scientifically proven method of predicting earthquakes.

A striking example of this situation occurred when NASA posted a feature article on its Web site in 2004 in which an earthquake prediction project it funded was heralded as an “amazing success” (see http://www.nasa.gov/vision/earth/environment/0930_earthquake.html). Because this kind of hyperbole is a constant source of frustration for scientists at Weston Observatory (Boston College, Weston, Mass.), where seismologists try to accurately report the state of the art of research on earthquake prediction to the public, we decided to test just how amazing this particular success was.
Taiwan shaken by an uncommon earthquake
Authors: Chao Benjamin F.
Published: April 2007

Exactly 2 years to the date after the great Sumatra earthquake, the island of Taiwan was shaken by an uncommon magnitude 7.1 earthquake and a series of aftershocks centered just off her southwestern coast on the continental shelf. The event is the largest in a century in that particular area, technically controlled by the subduction of the Eurasia plate under the Philippine plate, a rare and peculiar case of a lighter continental plate subducting under a heavier oceanic plate.

The main shock, at 1226 UT, 26 December 2006, had a moment magnitude of 7.1 as determined by the U.S. Geological Survey's National Earthquake Information Center (NEIC/USGS), followed by a 7.0 aftershock 8 minutes later, and three more subsequent aftershocks above magnitude 5 within a day. Relatively minor damage was reported on land, while underwater communication cables were severed at as many as seven locations at different times. A nearby nuclear power plant experienced a g‐force as large as 0.16g. A tsunami warning was issued in Vietnam and the Philippines but was later called off. The Broadband Array in Taiwan for Seismology (BATS) put the main shock depth at somewhat over 20 kilometers and deeper for the large aftershocks. The water depth at the epicenter region is no more than 600 meters.
Electronic spin transition of iron in the Earth's deep mantle
Authors: Lin Jung‐Fu , Jacobsen Steven D. , Wentzcovitch Renata M.
Published: April 2007

Electronic spin is a quantum property of every electron, associated with its intrinsic angular momentum. Though there are no suitable physical analogies to describe the spin quantum number, there are two possibilities, called spin ‘up’ and spin ‘down.’ The electronic structure of iron in minerals is generally such that valence electrons will more abundantly occupy different spatial orbitals and maintain the same spin than occupy the same spatial orbital and assume opposite spin, called ‘spin‐paired.’

To the astonishment of mineral physicists, pressure‐induced electronic spin‐pairing transitions of iron that were predicted nearly 50 years ago recently have been detected in major mantle‐forming oxides and silicates in ultrahigh‐pressure experiments at lower‐mantle pressures [e.g., Badro et al., 2003, 2004; Lin et al., 2005]. If such a spin transition is occurring in the Earth's lower mantle, there may be profound geophysical implications.
Online analysis enhances use of NASA Earth science data
Authors: Acker James G. , Leptoukh Gregory
Published: April 2007

Giovanni, the Goddard Earth Sciences Data and Information Services Center (GES DISC) Interactive Online Visualization and Analysis Infrastructure, has provided researchers with advanced capabilities to perform data exploration and analysis with observational data from NASA Earth observation satellites. In the past 5–10 years, examining geophysical events and processes with remote‐sensing data required a multistep process of data discovery, data acquisition, data management, and ultimately data analysis. Giovanni accelerates this process by enabling basic visualization and analysis directly on the World Wide Web. In the last two years, Giovanni has added new data acquisition functions and expanded analysis options to increase its usefulness to the Earth science research community.
U.S. climate change program releases annual report
Authors: Zielinski Sarah
Published: April 2007

The U.S. Climate Change Science Program (CCSP) has issued its Fiscal Year 2007 report to the U.S. Congress documenting the program's previous year's activities and its plans for the current year. The CCSP coordinates climate change research across 13 federal agencies and departments and oversees the creation and publication of the 21 CCSP synthesis and assessment reports, the first of which was published in April 2006. During FY2007, CCSP will focus on several areas including integrating new remotely sensed measurements of clouds and aerosols into climate prediction, acquiring a source for Landsat‐like imagery, developing research and regional partnerships to help the nation cope with drought, and quantifying the North American carbon budget.
Twenty years of nonlinear dynamics in geosciences
Authors: Elsner James B. , Gupta Vijay K. , Lovejoy Shaun , Lucarini Valerio , Murray A. Brad , Sharma A. Surjalal , Tebbens Sarah , Tsonis Anastasios A. , Vassiliadis Dimitris
Published: April 2007

Twenty years ago, the basic ideas of what is now known as ‘nonlinear geophysics’ had matured to the point that they were generating great excitement, motivating the first workshops on the theme. The ideas instigated new approaches to addressing problems of geophysics covering different disciplines, and they led to the publication of several important papers.

A conference entitled ‘20 Years of Nonlinear Dynamics in Geosciences’ was held in Rhodes, Greece, from 11 to 16 June 2006 to mark this progress. The aim of the conference was to bring together scientists from all areas of geosciences to discuss problems, review advances, and look toward the future. About 80 scientists from around the world participated in the meeting. This article provides a brief review of the key historical developments that laid the foundations for nonlinear geophysics and gives an overall summary of the meeting.
Marine heat flow measurements in hard ground offshore Sumatra
Authors: Delisle Georg , Zeibig Michael
Published: April 2007

The hydrocarbon potential of the fore arc basins between the Siberut, Nias, and Simeulue islands and Sumatra was investigated in 2006 by the German Federal Geological Survey (BGR) with marinegeophysical and marine‐geological techniques (cruises SO‐189‐1 and SO‐189‐2). The basin sediments are relatively coarse grained (in part, of volcanic origin). In most locations, they are too hard for the use of conventional heat flow probes, which penetrate only muddy to soft seafloor sediments.

To overcome this restriction and to measure in situ heat flow in hard‐ground terrain of these fore arc basins, a new ‘hard‐ground heat flow probe’ was developed and successfully employed at 10 stations during the SO‐189 cruises. A conventional heat flow probe was operated at six additional stations. The development of the new probe initially was motivated by the observation of widespread ‘hard ground’ along the outer‐arc high of the accretionary prism at the southern coast of Java in 1999 (marine cruise GINCO, leg SO‐139‐2 of BGR).
Southwestern U.S. drought maps from pinyon tree‐ring carbon isotopes
Authors: Leavitt Steven W. , Chase Thomas N. , Rajagopalan Balaji , Lee Eungul , Lawrence Peter J. , Woodhouse Connie A.
Published: April 2007

Tree‐ring widths have long been a useful North American drought proxy [e.g., Cook et al., 1999, 2004]. A potentially rich, new tree‐ring proxy associated with the tree's leaf‐level moisture status is stable‐carbon isotope composition (δ13C = [13C/12Csample ÷ 13C/12Cstandard − 1[ × 1000), which is determined by both the rate of carbon assimilation and the rate of gas conductance through leaf stomata [Farquhar et al., 1982]. In the U.S. Southwest, where evaporation exceeds precipitation, drought may be the dominant influence on plant δ>13C [Warren et al., 2001], so measurements of tree‐ring δ13C in a network of southwestern sites has allowed for spatially mapping this ecophysiological indicator back to A.D. 1600.

Stomatal portals are the primary avenues of water loss and carbon gain in plants, providing carbon dioxide (CO2) for photosynthesis, which tends to discriminate against fixation of 13CO2 in favor of 12CO2. In principle, under conditions of water stress the stomata close down and the reservoir of CO2 available for continued photosynthesis is reduced, proportionally more 13CO2 is fixed, and the 13C/12C ratio of sugars eventually incorporated into tree rings increases (i.e., δ13C increases), and vice versa during moist conditions.
Understanding sea level rise and variability
Authors: Church John , Wilson Stan , Woodworth Philip , Aarup Thorkild
Published: April 2007

The coastal zone changed considerably during the twentieth century due to growing populations and increasing urbanization. A recent study indicated that in 1990, 23% of the world's population (1.2 billion people) were living within both a 100‐kilometer distance and a 100‐meter elevation of the coast at densities 3 times higher than the global average. Society is becoming increasingly vulnerable to sea level extremes, as Hurricane Katrina demonstrated. Rising levels will result in more flooding, even if storm intensities do not increase. Improved understanding of the reasons for sea level rise and variability is required to reduce the uncertainties in sea level rise projections, and this improved understanding could contribute to more effective coastal planning and management.
Hazards from hydrothermally sealed volcanic conduits
Authors: Christenson Bruce W. , Werner Cynthia A. , Reyes Agnes G. , Sherburn Steve , Scott Bradley J. , Miller Craig , Rosenburg Michael J. , Hurst Anthony W. , Britten Karen A.
Published: April 2007

The 17 March 2006 eruption from Raoul Island (Kermadec arc, north of New Zealand) is interpreted as a magmatic‐hydrothermal event triggered by shaking associated with a swarm of local earthquakes. The eruption, which tragically claimed the life of New Zealand Department of Conservation Ranger Mark Kearney, occurred without significant volcanic seismicity or any of the precursory responses the volcanic hydrothermal system exhibited prior to a similarly sized eruption in 1964.

Preliminary evidence suggests that the absence of precursory behavior is probably the consequence of hydrothermal sealing of the volcanic conduit since the 1964 eruption, and points to potential hazards associated with quiescent oceanic island volcanoes.
A unified database of large European earthquakes
Authors: Grünthal Gottfried , Wahlström Rutger
Published: April 2007

Understanding the potential for large earthquake disasters in the Euro‐Mediterranean region, including effects from tsunamis, is a high priority in the European seismological community. Accurate locations and magnitudes are of utmost importance in order to determine various parameters needed for seismic hazard assessment.

Data from local earthquake catalogues for all of Europe and the near surroundings have now been compiled and homogenized in historical as well as instrumental time. This new database concentrates on large earthquakes (Mw≥6). Studies of this new database conclude that the earthquake locations concentrate around main tectonic features with less scatter than has been provided by existing databases from international seismological agencies and other previous compilations.
Coordinating Earth Observing System land validation
Authors: Nickeson Jaime E. , Morisette Jeffrey T , Privette Jeffery L. , Justice Christopher O. , Wickland Diane E.
Published: April 2007

NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) land product validation project, initiated prior to the launch of the NASA Earth Observing System (EOS) Terra platform in late 1999, provides data, instrument, and information resources for the validation of products that quantify land surface characteristics from MODIS and other satellite sensors. Land products derived from MODIS and other moderate‐resolution sensors include, among others, land cover, snow cover extent, surface temperature, leaf area index, fire occurrence, and vegetation productivity.

The land validation project infrastructure, developed at NASA's Goddard Space Flight Center (GSFC), involves an integration of NASA‐funded researchers, international collaborators, and science data networks. These resources facilitate determination of product uncertainty, which is the definition of validation, through best practice methods. Key to the project is the set of EOS Land Validation Core Sites, a global network of 33 sites (including six added in 2006), which serve as a focus for validation activities. The initial infrastructure and activities were described in Morisette et al. [1999], Justice et al. [2000], and Morisette et al. [2002].
Wahr receives 2006 Charles A. Whitten medal
Authors: Wahr John M.
Published: April 2007

It is a pleasure and an honor to present the citation to John M. Wahr for the Charles A. Whitten Medal, which is an award for outstanding achievement in research on the form and dynamics of the Earth. John has made fundamental advances in many areas of dynamics, including time‐variable gravity, Earth rotation, Earth and ocean tides, interaction of the atmosphere and ocean with the Earth, postglacial deformation, and nutation. He has published papers in geodesy, geodynamics, seismology, geomagnetism, hydrology, cryospheric sciences, oceanography, atmospheric sciences, planetary sciences, and even general relativity.

John is a major intellectual leader in much of geophysics with a heavy emphasis on global‐scale problems involving the fluid envelope. John broke new ground with his work in the application of geodetic data to geophysical problems, including global tides, barometric response of the oceans, and Earth rotation. His unique contributions came from developing the theory, and modeling Earth tides, nutations, and various other types of rotational and deformational motion. Both the Earth tide model and the nutation model served as the adopted international standards for almost 20 years. His cutting‐edge work on time‐variable gravity has enabled him to blaze a new trail for interdisciplinary geodesy.
Effects of eddies on Bay of Bengal cyclone intensity
Authors: Ali M. M. , Jagadeesh P. S. V , Jain Sarika
Published: April 2007

Predicting cyclone intensities in the Indian Ocean has been a challenging problem. Because of the highly varying bathymetry of the Indian coast, even a slight error in the prediction of landfall point and intensity can lead to a totally different storm surge height. Though capabilities of cyclone track prediction have significantly improved during recent years, cyclone intensity forecasts still need improvement. Various dynamical and statistical models have different rates of success for cyclone intensity prediction. In addition to atmospheric parameters and sea surface temperature (SST), another important parameter that enhances the understanding of the intensification of the cyclones is the upper ocean heat storage that is generally reflected in the oceanic eddies and dynamic topography. Sea surface height anomalies (SSHAs) from radar altimeters can provide information on this parameter. The relationship between the SSHAs and the associated hydrographic structure, particularly of eddies, is discussed by Ali et al. [1998], Gopalan et al. [2000], Babu et al. [2003], and Gopalakrishna et al. [2003]. Because of these changes in hydrographic features caused by SSHAs, warm (cold) core oceanic eddies have more (less) heat content compared with their surroundings.
Arsenic removal challenge
Authors: Zielinski Sarah
Published: April 2007

Arsenic contaminates the well water used by millions of Bangladeshis (see Eos 87(3), 2006). Now, the developer of a household treatment system that removes arsenic from water will receive the 2007 Grainger Challenger Prize Gold Award, the U.S. National Academy of Engineering announced on 1 February. Abul Hussam, of George Mason University in Fairfax, Va., developed a filter system, known as the SONO filter, which is manufactured and used in his native Bangladesh. The academy also announced several other award winners. Additional information is available at http://www.nae.edu/nae/grainger.nsf
Cashman receives 2006 N. L. Bowen Award
Authors: Lange Rebecca , Cashman Katharine
Published: April 2007

Katharine Cashman received the N. L. Bowen Award at the 2006 AGU Fall Meeting. The award recognizes outstanding contributions to volcanology, geochemistry, or petrology.

It is a privilege and an honor to present the N. L. Bowen citation for Kathy Cashman. She is richly deserving of this recognition owing to her unique and original contributions to the field of volcanology.
Risk of rising sea level to population and land area
Authors: Rowley Rex J. , Kostelnick John C. , Braaten David , Li Xingong , Meisel Joshua
Published: April 2007

Low‐elevation land areas and their populations are at risk globally from rising sea level. Global sea level has risen by about 2 millimeters per year over the past century. About half of this rise may be attributed to thermal expansion of the ocean and the melting of temperate‐latitude glaciers [Dyurgerov and Meier, 1997]. The remainder of the rise is believed to come from a net loss of mass from the Antarctic and Greenland ice sheets, although the exact contribution is unknown.
Legislators urge carbon emissions cuts
Authors: Kumar Mohi
Published: April 2007

Legislators from the world's largest carbon dioxide (CO2 ) emitting countries met on 14–15 February in Washington, D.C., to discuss the future of the global climate and strategies to mitigate temperature increases resulting from global warming.

The world faces a “double challenge— how to reduce damaging carbon emissions while still meeting the energy demand that the world's poor need to escape poverty,” said World Bank President Paul Wolfowitz during a keynote talk.
Reply to Comment on Snowball Earth
Authors: Allen Philip A.
Published: April 2007

I welcome the signs of a dialectical engagement in the evaluation of the Snowball Earth hypothesis.

Paul Hoffman proposes that on the basis of Kirschvink's two‐page chapter [Kirschvink, 1992], there are five main pillars in support of the Snowball Earth hypothesis. I cannot agree that the five pillars mentioned by Hoffman can be discerned in Kirschvink's original piece. A pillar must be a line of argument and supporting data that the protagonist views as being strongly and uniquely supportive of the hypothesis. Using the architectural metaphor, a pillar is solid, supportive, and unchanging. There are no such pillars in Kirschvink's article. He admits that his hypothesis is “speculative” (p. 51) or, more precisely, involves an alternate “equally speculative mechanism” to that of high obliquity to explain apparently low‐latitude glaciation. Kirschvink suggested that there were several implications of his global snowball model, but no compelling evidence was presented.
Reconstruction of past Mediterranean climate
Authors: García‐Herrera Ricardo , Luterbacher Jürg , Lionello Piero , González‐Rouco Fidel , Ribera Pedro , Rodó Xavier , Kull Christoph , Zerefos Christos
Published: April 2007

Mediterranean Climate Variability and Predictability (MEDCLIVAR; http://www.medclivar.eu) is a program that coordinates and promotes research on different aspects of Mediterranean climate. The main MEDCLIVAR goals include the reconstruction of past climate, describing patterns and mechanisms characterizing climate space‐time variability, extremes at different time and space scales, coupled climate model/empirical reconstruction comparisons, seasonal forecasting, and the identification of the forcings responsible for the observed changes. The program has been endorsed by CLIVAR (Climate Variability and Predictability project) and is funded by the European Science Foundation.

The main purpose of this first MEDCLIVAR workshop was to identify sources of early instrumental data and natural and documentary climate proxies that had not been previously explored and/or identified and that could be relevant for the reconstruction of the Mediterranean climate or weather extremes covering the past millennia. A key focus was on weather and climate information with high temporal (annual or higher) and spatial resolution as well as the potential to resolve past climate variability based on low‐resolution proxies covering the past tens of thousands to hundreds of thousands of years.
A very active sprite‐producing storm observed over Argentina
Authors: Thomas Jeremy N. , Taylor Michael J. , Pautet Dominique , Bailey Matthew , Solorzano Natalia N. , Holzworth Robert H. , McCarthy Michael P. , Kokorowski Michael , Sabbas Fernanda Sao , Pinto Osmar , Cummer Steven A. , Jaugey Nicolas , Li Jingbo , Schuch Nelson Jorge
Published: April 2007

During the night of 22–23 February 2006, more than 400 middle‐atmospheric optical discharges were observed above one large thunderstorm system over northeastern Argentina. These transient luminous events (TLEs) were imaged during the Southern Brazil Sprite Campaign, the first campaign to focus on TLEs over southern Brazil, northeastern Argentina, and Uruguay. All of the TLEs were imaged from the Brazilian Southern Space Observatory (SSO) near Santa Maria, which is nearly in the center of the southernmost Brazilian state of Rio Grande do Sul. Although the fields of view of the imaging cameras were too narrow to view the entire storm, the more than 400 confirmed TLEs imaged indicate that this storm ranks as the third most active TLE producer ever reported. Hence, storms in this region of South America might be some of the leading TLE generators on Earth.
Sea level rise in Tampa Bay
Authors: Cronin Thomas , Edgar N.Terence , Brooks Gregg , Hastings David , Larson Rebekka , Hine Albert , Locker Stanley , Suthard Beau , Flower Benjamin , Hollander David , Wehmiller John , Willard Debra , Smith Shannon
Published: April 2007

Understanding relative sea level (RSL) rise during periods of rapid climatic change is critical for evaluating modern sea level rise given the vulnerability of Antarctic ice shelves to collapse [Hodgson et al, 2006], the retreat of the world's glaciers [Oerlemans, 2005], and mass balance trends of the Greenland ice sheet [Rignot and Kanagaratnam, 2006]. The first‐order pattern of global sea level rise following the Last Glacial Maximum (LGM, ∼21,000 years ago) is well established from coral [Fairbanks, 1989], continental shelf [Hanebuth et al, 2000], and other records [Pirazzoli, 2000] and has been integrated into a global ICE‐5G model of glacio‐isostatic adjustment (GIA) [Peltier, 2004]. However, uncertainty introduced by paleo water depth of sea level indicators, radiocarbon chronology (i.e., reservoir corrections for marine shell dates), postglacial isostatic adjustment, and other processes affecting vertical position of former shorelines produces scatter in RSL curves, limiting our knowledge of sea level rise during periods of rapid glacial decay.

One example of this limitation is the Gulf of Mexico/Florida region where, despite decades of study, RSL curves produce two conflicting patterns: those showing progressive submergence with a decelerating rate during the past 5000 years [Scholl et al, 1969] and those showing high sea level during the middle of the Holocene [Blum et al, 2001; Balsillie and Donoghue, 2004], where the Holocene represents a geologic epoch that extends from about 10,000 years ago to present times. This discrepancy is emblematic of the uncertainty surrounding Holocene sea level and ice volume history in general.
AGU Book receives two awards
Authors: Anonymous
Published: April 2007

Atmospheric Halos and the Search for Angle x, by Walter Tape and Jarmo Moilanen, recently has been honored with two awards. In January 2007, Atmospheric Science Librarians International (ASLI) recognized the book as the 2006 ASLI Choice Award, Honorable Mention for an excellent illustrated update to a niche topic in the fields of meteorology, climatology, and atmospheric sciences. In February, the book received the 2006 Professional and Scholarly Publishers Award for Excellence, Honorable Mention Award in the geology and geography category. PSP is a division of the Association of American Publishers. The book, published by AGU in 2006, includes sections on how to observe and photograph halos, the early history of halo science, new explanations of how halos form, and a discussion of odd radius halos.
The Earth's Magnetism: An Introduction for Geologists
Authors: Harlan Stephen S.
Published: April 2007

The nature of the geomagnetic field is one of the cornerstones of the study of the geophysical properties of the Earth. Despite the importance of geomagnetism to the understanding of the Earth and to the various subdisciplines of geophysics, and despite its being an essential part of any Earth scientist's education, it has been suggested that most geophysics textbooks and curricula devote only limited attention to the subject. With this in mind, Roberto Lanza and Antonio Meloni have authored The Earth's Magnetism: An Introduction for Geologists with the goal of producing a textbook that would provide a holistic approach to the subject and a general overview of many of the fundamental subjects that compose geomagnetism and its applications to geology. The text is meant to supplement more substantial treatments of various subjects and the geomagnetic literature.
[Comment on “A turning point in auroral physics”] An apparent controversy in auroral physics
Authors: Haerendel Gerhard
Published: April 2007

In his article “A turning point in auroral physics,” Bryant [2006] argued against what he called the ‘standard’ theory of auroral acceleration, according to which the electrons “gain their energy from static electric fields,” and offered wave acceleration as an alternative. Because of the importance of the process, not only for the aurora borealis but also for other cosmic plasmas, a clarification of this apparent controversy seems to b e in place.

Indeed, theoretical descriptions of the acceleration process often use an electrostatic approach. One postulates or derives a quasi‐Ohm's Law for the relation between current density and potential drop along the magnetic field and attributes the energy gain of the electrons to the ‘fall’ through this potential drop. Strong confirmation comes from the findings that a ‘potential,’ derived from integrating the transverse electric field measured by a satellite crossing above an auroral arc, agrees well with the energy gain of ions accelerated below the spacecraft [e.g., McFadden et al., 1999]. The solution of the problem lies in the word ‘nearly’ In the height range of several thousand kilometers, where auroral acceleration is concentrated, the electric field is nearly electrostatic. In reality, it is applied by an electromagnetic Alfvén wave launched in the outskirts of the magnetosphere. When it reaches the stiff magnetic field near Earth, where its phase speed is close to the velocity of light, it traverses the acceleration region so fast that a nearelectrostatic description of the field is permissible. However, above the low magnetosphere the field continues as an induction field. In other words, auroral field lines are not equipotentials. In conclusion, Bryant is right in principle but wrong in discarding auroral acceleration by nearly electrostatic fields.
In Memoriam
Authors: Anonymous
Published: April 2007

Tor Hagfors, 76, 17 January 2007; Space Physics and Aeronomy, 1963
Rapid climate change and the role of the ocean circulation
Authors: Srokosz Meric , Wolff Eric , Byfield Valborg
Published: April 2007

The role of the North Atlantic meridional overturning circulation (MOC) in possible future rapid climate changes is much debated. The U.K. Natural Environment Research Council initiated a program called Rapid Climate Change (RAPID) to investigate this issue, working with international partners. The recent Rapid Climate Change International Science Conference reviewed progress and discussed the scientific challenges in this area, bringing together results from paleoclimatology, modeling, and observational studies.

About 8000 years ago, a sharp drop in temperatures occurred when an outburst from a North American ice‐dammed lake (Lake Agassiz) flooded the North Atlantic with freshwater. The event is a possible analogue for potential effects of future North Atlantic freshening from increased precipitation and ice melt. Speakers presented evidence suggesting that the nature of the event is becoming clearer, including the first clear evidence of its impact on the MOC. However, the relationship between the timing of various changes and the lake's outburst needs further investigation.
Estimation of solar‐induced vegetation fluorescence from space measurements
Authors: Guanter L. , Alonso L. , Gómez‐Chova L. , Amorós‐López J. , Vila J. , Moreno J.
Published: April 2007

A characteristic spectral emission is observed in vegetation chlorophyll under excitation by solar radiation. This emission, known as solar‐induced chlorophyll fluorescence, occurs in the red and near infra‐red spectral regions. In this paper a new methodology for the estimation of solar‐induced chlorophyll fluorescence from spaceborne and airborne sensors is presented. The fluorescence signal is included in an atmospheric radiative transfer scheme so that chlorophyll fluorescence and surface reflectance are retrieved consistently from the measured at‐sensor radiance. This methodology is tested on images acquired by the Medium Resolution Imaging Spectrometer (MERIS) on board the ENVIronmental SATellite (ENVISAT) taking advantage of its good characterization of the O2‐A absorption band. Validation of MERIS‐derived fluorescence is carried out by applying the method to data acquired by the Compact Airborne Spectrographic Imager (CASI‐1500) sensor concurrently to MERIS acquisitions. CASI‐derived fluorescence is in turn compared with ground‐based fluorescence measurements, a correlation coefficient R2 of 0.85 being obtained.
Quantitative insights into stochastic monoallelic expression of cytokine genes
Authors: Paixão Tiago , Carvalho Tiago P , Calado Dinis P , Carneiro Jorge
Published: April 2007

Gene expression from both parental alleles is beneficial by masking the effects of deleterious recessive mutations and by reducing the noise in gene expression in diploid organisms. However, a class of genes are expressed preferentially or strictly from a single allele. The selective advantage of avoiding biallelic expression is clear for allelic‐excluded antigen receptor and odorant receptor genes, genes undergoing X‐chromosome inactivation in females and parental genomic imprinted genes. In contrast, there is no clear biological rationale for the predominant and stochastic monoallelic expression of cytokine genes in the immune system, and the underlying mechanism is elusive and controversial. A clarification of the mechanism of predominant monoallelic expression would be instrumental in better understanding its eventual biological functional. This prompted the development of a quantitative framework that could describe the dynamics of the pattern of allele expression of the IL‐10 gene, from which general quantitative insights could be gained. We report that the experimental observations on these patterns of allelic expression cannot be easily reconciled with a simple model of stochastic transcriptional activation, in which the two alleles are, at any time, equally competent for transcription. Instead, these observations call into action a general model of eukaryotic transcriptional regulation according to which the locus competence for transcription is dynamic, involving multiple, cooperative and stochastic modification steps. In this model, the probability that an allele becomes transcriptionally active is a function of the number of chromatin modifications that it accumulated. On the basis of the properties of this model, we argue that predominant monoallelic expression might have had no adaptive role, and may have evolved under indirect selection for low frequency of expressing cells.
Performance Measurement in Small Motels in Australia: (Funded by the Sustainable Tourism Co-operative Research Centre)
Authors: Bergin-Seers Suzanne , Jago Leo
Published: April 2007

This research explores the measurement of performance in small motels. There are many challenges facing business performance management in small firms. Most of these challenges are due to resource shortages, lack of functional expertise and environmental instability. Of major importance to firm survival is the small enterprise owner-manager's ability to monitor the operations performance. Key components of the monitoring process include the ability to identify key performance indicators to track results as well as an understanding of the most suitable measures to use. Specifically, the study focuses on identifying the key constructs of performance for small firms that include the key components of drivers and results. The specific monitoring and measurement activities of small motel owner-operators were identified using a case research approach. The findings of the study indicate that those owner-managers who operate successful motels employ a balanced approach to performance measurement by utilising a small number of key measures to monitor results and to review management activities.
Trials and Tribulations of Hotel Ownership in Blackpool: Highlighting the Skills Gaps of Owner-Managers
Authors: Lashley Conrad , Rowson Bill
Published: April 2007

The research reported on in this paper suggests that people who buy hotels in Blackpool are doing so for a cluster of lifestyle reasons. Few have classic entrepreneurial ambitions to make a lot of money and own a chain of hotels. Many have a lifelong ambition to own a hotel, or some business that gives them greater control of their lives, or because they think they will enjoy the life of hotel ownership. The vast majority of these interviewees had sold a domestic property to buy the hotel, and few had any work experience of hotel work, or even the hospitality sector. This lack of experience of the operational requirements of the business was further compounded by a lack of management skills, or small business experience. As a consequence, the professional skills of hotel management are often below par and hotel ownership changes hands at an unacceptable rate. Sometimes this results in outright business failure, but more often, is the result of individuals feeling that the reality of hotel ownership has not matched their dreams. The low skill base of the almost permanent cadre of new owners creates problems for tourism authorities keen to develop the quality profile of visitor experiences. There is limited development of the hotel stock as individual properties change hands on a regular basis and no one owner stays long enough to refurbish the property. The low skill base of owners can also limit the quality tourism experiences of services provided.
Explorations of the Host's Relationship with the Commercial Home
Authors: Sweeney Majella , Lynch Paul A.
Published: April 2007

This paper investigates the host's relationship with their commercial home and its influences on product construction. Intangible dimensions of hospitality are explored through interviews and photographs. Commercial home hosts are interviewed using photographs taken of their property to investigate the relationship they have with their commercial home, deepening our understanding of the host—home relationship, leading to a more sophisticated and nuanced appreciation of how the commercial home ‘home’ product is constructed. The study is based on six commercial homes units. It is envisaged that in the future further issues will be identified from additional unit studies. A selection of themes is identified from preliminary analysis and areas for future research are suggested. The outcome of this research will include a deeper understanding of the commercial home product construction and the commercial home sector itself, which may lead to recommendations contributing towards the nature of quality assurance and grading systems, training and development strategies appropriate to the commercial home concept, and potential implications of marketing. This research is distinguished from what has gone before as prior studies have focused on readily accessible ‘objective’ issues, rather than below the surface issues accessing the inner self, the intangible dimensions of self, which nevertheless may determine aspects of the hospitality product.
Evidence for room temperature ferromagnetism in CuxZn1−xO from magnetic studies in CuxZn1−xO∕CuO composite
Authors: Seehra M. S. , Dutta P. , Singh V. , Zhang Y. , Wender I.
Published: April 2007

Magnetic studies in bulk 57% CuxZn1−xO∕43% CuO composite prepared chemically with x=0.10 (0.03) are reported. Temperature dependence of the magnetic susceptibility shows clear signature of the Néel temperature TN≃230K for pure CuO. Hysteresis loop studies in the zero-field-cooled sample show room-temperature ferromagnetism with coercivity Hc≃50Oe at 300K with strong temperature dependence for T<300K. A negative exchange bias He at 5K is observed when the sample is cooled from RT in H=20kOe, and its temperature dependence yields He→0 at TN=230K of CuO. These results and the temperature dependence of remanence Mr provide strong evidence that the CuxZn1−xO phase with x≃0.10 is a ferromagnet with Tc≃400K. An electron magnetic resonance signal due to Cu2+ substituting for Zn2+ in CuxZn1−xO is also observed.
Influence of the Damköhler number on turbulence-scalar interaction in premixed flames. I. Physical insight
Authors: Chakraborty N. , Swaminathan N.
Published: April 2007

Scalar dissipation rate is a central quantity in turbulent flame modeling as it is closely related to the reaction rate. It is well known that turbulence-scalar interaction plays a vital role in turbulent flows with scalar mixing and thus on the scalar dissipation rate. This interaction process is characterized by the tensor inner product between the scalar gradient vector and the turbulence strain rate tensor and it is found to depend strongly on the Damköhler number, Da. Two direct numerical simulation data sets are analyzed in detail in order to understand the physics of Da dependence. The well known alignment of scalar gradient with the most compressive principal strain rate resulting in production of the scalar gradient by turbulence is observed for low (Da<1) Damköhler number flame, whereas the turbulence dissipates the scalar gradient in high Da flame. This dissipation of the scalar gradient in the high Da flame is because of its preferential alignment with the most extensive principal strain rate. Even for Da<1 flame, in the regions of intense heat release the scalar gradient has a tendency to align with the most extensive strain rate. This distinct change is because of strong competition between chemical strain rate, due to dilatation from the flame front and the local fluid dynamic strain rate. The alignment characteristics affect flame normal and tangential strain rate statistics. The flame normal strain rate is found to be positive throughout the flame brush when Da>1, whereas it is predominantly negative when Da<1. Despite this difference the mean tangential strain rate remains positive yielding flame surface area production. However, the production results via different physical mechanisms. Possible implications of these differences on the modeling of turbulent premixed flames are identified and explained.
Two-dimensional simulation of nanoparticle deposition from high-density plasmas on microstructured surfaces
Authors: Rutkevych P. P. , Ostrikov K. , Xu S.
Published: April 2007

Selective and controlled deposition of plasma-grown nanoparticles is one of the pressing problems of plasma-aided nanofabrication. The results of advanced numerical simulations of motion of charge-variable nanoparticles in the plasma presheath and sheath areas and in localized microscopic electric fields created by surface microstructures are reported. Conditions for site-selective deposition of such nanoparticles onto individual microstructures and open surface areas within a periodic micropattern are formulated. The effects of plasma parameters, surface potential, and micropattern features on nanoparticle deposition are investigated and explained using particle charging and plasma force arguments. The results are generic and applicable to a broad range of nanoparticle-generating plasmas and practical problems ranging from management of nanoparticle contamination in microelectronics to site-selective nanoparticle deposition into specified device locations, and synthesis of advanced microporous materials and nanoparticle superlattices.
Capillary instabilities of liquid films inside a wedge
Authors: Yang Li , Homsy G. M.
Published: April 2007

We consider a liquid meniscus inside a wedge of included angle 2β that wets the solid walls with a contact angle θ. The meniscus has a convex interface that satisfies π∕2<θ+β<π. The capillary pressure gradient due to a small disturbance of the location of the contact line moves fluid from a neck region to a bulge region, causing instabilities. A dynamic contact-line condition is considered in which the contact angle varies linearly with the slipping speed of the contact line with a slope of G:G=0 representing perfect slip and a fixed contact angle. A nonlinear thin film equation is derived and numerically solved for the shape of the contact line as a function of parameters. The result for G=0 shows that the evolution process consists of a successive formation of bulges and necks in decreasing length and time scales, eventually resulting in a cascade structure of primary, secondary, and tertiary droplets. When G>0, there is a similar but slower nonlinear evolution process. The numerical results agree qualitatively with very recent experimental results.
Is the magnetoelectric coupling in stickup bilayers linear?
Authors: Zhang N. , Liang Dekai , Schneider T. , Srinivasan G.
Published: April 2007

The magnetoelectric (ME) characterization of stickup bilayers Ni0.8Zn0.2Fe2O3-Pb(Zr, Ti)O3 and trilayers of Ni0.8Zn0.2Fe2O3-Pb(Zr, Ti)O3-Ni0.8Zn0.2Fe2O3 are discussed. The ME interactions in the trilayers were found much stronger than that of bilayers prepared with the same technique. The maximum transverse ME voltage coefficient of trilayer can reach 430 (mV/cm Oe) under a magnetic field H=215 Oe. This value is much closer to the theoretical estimate for the ME coupling for bilayers. The frequency dependence of αE also reveals the difference of the elastic and magnetoelectric coupling between the bilayers and trilayers. Analysis suggests that a more approach linear response of the pezioelectric layer to the magnetostriction of the ferrite may be responsible for the significant enhanced ME effect in the trilayers.
Bright, guided molecular beam with hydrodynamic enhancement
Authors: Patterson David , Doyle John M.
Published: April 2007

The authors realize a novel high flux source of cold atoms and molecules employing hydrodynamic enhancement of an effusive aperture at cryogenic temperatures. Molecular oxygen from the source is coupled to a magnetic guide, delivering a cold, continuous, guided flux of 3×1012O2s−1. The dynamics of the source are studied by creating and spectroscopically analyzing high flux beams of atomic ytterbium.
Quantum state tomography for quadrupolar nuclei using global rotations of the spin system
Authors: Teles J. , deAzevedo E. R. , Auccaise R. , Sarthour R. S. , Oliveira I. S. , Bonagamba T. J.
Published: April 2007

In this paper, we describe a quantum state tomography method based on global rotations of the spin system which, together with a coherence selection scheme, enables the complete density matrix reconstruction. The main advantage of this technique, in respect to previous proposals, is the use of much shorter rf pulses, which decreases significantly the time necessary for algorithm quantum state tomography. In this case, under adequate experimental conditions, the rf pulses correspond to simple spatial rotations of the spin states, and its analytical description is conveniently given in the irreducible tensor formalism. Simulated results show the feasibility of the method for a single spin 7∕2 nucleus. As an experimental result, we exemplify the application of this method by tomographing the steps during the implementation of the Deutsch algorithm. The algorithm was implemented in a Na23 quadrupole nucleus using the strongly modulated pulses technique. We also extended the tomography method for a 3-coupled homonuclear spin 1∕2 system, where an additional evolution under the internal Hamiltonian is necessary for zero order coherences evaluation.