bluuebunny/crossref_metadata_2025 huggingface dataset:
Osteopontin in macrophage function
Authors: Rittling Susan R.
Published: April 2011

The secreted phosphorylated protein osteopontin (OPN) is expressed in a variety of tissues and bodily fluids, and is associated with pathologies including tissue injury, infection, autoimmune disease and cancer. Macrophages are ubiquitous, heterogeneous cells that mediate aspects of cell and tissue damage in all these pathologies. Here, the role of OPN in macrophage function is reviewed. OPN is expressed in macrophage cells in multiple pathologies, and the regulation of its expression in these cells has been described in vitro. The protein has been implicated in multiple functions of macrophages, including cytokine expression, expression of inducible nitric oxide synthase, phagocytosis and migration. Indeed, the role of OPN in cells of the macrophage lineage might underlie its physiological role in many pathologies. However, there are numerous instances where the published literature is inconsistent, especially in terms of OPN function in vitro. Although the heterogeneity of OPN and its receptors, or of macrophages themselves, might underlie some of these inconsistencies, it is important to understand the role of OPN in macrophage biology in order to exploit its function therapeutically.
Introduction to the Special Issue on Ottocento Opera
Authors: Marvin Roberta Montemorra
Published: April 2011

In the early 1960s a PhD candidate at Princeton University informed his professors that he wished to write a dissertation on the operas of Gioachino Rossini. He was pointedly discouraged from doing so and told that, if he wished to be taken seriously in musicology, he should focus on worthwhile repertory such as Renaissance music or works by nineteenth-century German composers. The student persisted in his purpose and, with his groundbreaking dissertation, set the study of ottocento opera on a solid trajectory. That student was Philip Gossett. Recently, at a gala event celebrating Philip's ‘retirement’, many of us who have focused our scholarship on this repertory were reminded about the evolution of the study of nineteenth-century Italian opera during the past 50 years.
‘Repatriating’ Falstaff: Boito, Verdi and Shakespeare (in Translation)
Authors: Gallo Denise
Published: April 2011

In 1946, W.H. Auden began a series of weekly lectures on Shakespeare's plays at New York's New School for Social Research. Arriving at The Merry Wives of Windsor, he pronounced it ‘a very dull play indeed’. Nevertheless, he allowed, ‘We can be grateful for its having been written, because it provided the occasion of Verdi's Falstaff, a very great operatic masterpiece’. Having nothing to say about The Merry Wives, he played a recording of the opera for the duration of the class.
Porgy and Bess: “An AmericanWozzeck”
Authors: REYNOLDS CHRISTOPHER
Published: April 2011

George Gershwin greatly admired Alban Berg and his operaWozzeck. He visited Berg in Vienna; the score he owned ofWozzeckwas reputedly one of his prize possessions; and he traveled to Philadelphia in 1931 to attend the American premiere. This study argues that Gershwin'sPorgy and Bessis heavily indebted to Berg'sWozzeck. The debts primarily involve structural processes—understanding structure as patterns of discrete events shared by the two operas. Motives and chords play a small role in the discussion, taking their place alongside musical events that range from the large—a fugue or a lullaby—to the small—a pedal, an ostinato, or some detail of counterpoint. Beyond the presence in both operas of a lullaby, a fugue, a mock sermon, and an upright piano, the greater relevance of these parallels and others is to be found in the ways in which Gershwin situated them in comparable musical contexts. Evidence, in the form of an overlooked interview and a previously unknown recollection by one of Gershwin's friends, supports this argument and leads to questions about how we are to understand Gershwin's use ofWozzeck.
Reconceptualizing Church and State: A Theoretical and Empirical Analysis of the Impact of Separation of Religion and State on Democracy
Authors: Brathwaite Robert , Bramsen Andrew
Published: April 2011

This article argues that the relationship between democracy and the separation of religion and state needs to be reexamined. We argue that previous studies have misconceptualized the impact that a lack of church-state separation can have on democracy, or have taken a narrow focus by concentrating on specific cases. We use principal component analysis and a large-ndata set covering 125 countries to show that the separation of religion and state should be conceptualized multi-dimensionally and that it should be considered a component of democracy. Our findings show that as separation of religion and state increases, the level of democracy also increases.
Not in His Image: The Moderating Effect of Gender on Religious Appeals
Authors: Calfano Brian R. , Djupe Paul A.
Published: April 2011

Religious appeals have been part and parcel of campaign strategy for decades. Most often, however, these appeals to have come from men, but little is known about howwomenwould fare using religious appeals on the campaign trail. To remedy this, we used an experimental design to examine voter reaction to religious appeals from a female and a male candidate competing for an open United States Senate seat. We find that women's use of religious appeals is governed by the dynamics of tokenism — reinforcing traditional gender stereotypes and serving to reduce voter support of the female candidate. This suggests that women must be careful in using a key campaign tool traditionally employed by men, and that this may affect the extent to which female candidates can effectively shape voter perceptions on the campaign trail.
Breaking the Chains?: Constraint and the Political Rhetoric of Religious Interest Groups
Authors: Knutson Katherine E.
Published: April 2011

Some scholars of religious interest groups argue that one challenge facing religious groups in their pursuit of political goals is that they are unwilling or unable to compromise, which makes it difficult for them to operate strategically within the secular political environment. An alternate explanation is that the types of arguments religious groups use are multifaceted but do not filter into the public discourse. In this article, I examine the concept of constraint in the context of mediated debates of contentious political issues by looking at the extent to which religious and nonreligious groups differ in their development of argument frames. Compared with nonreligious groups, religious groups do display more evidence of constraint in mediated debates over public policies. Patterns of constraint relate to visibility, framing, group resources, and group purpose. More importantly, however, I find that the patterns of constraint have more to do with journalistic decisions to filter arguments made by religious groups than with the actual rhetorical strategies of religious groups.
Learning about World Religions in Modesto, California: The Promise of Teaching Tolerance in Public Schools
Authors: Lester Emile , Roberts Patrick S.
Published: April 2011

After cultural and religious controversy in Modesto, California, community leaders attempted to increase tolerance and respect by requiring an unique world religions course for high school students. The first large-n empirical study of the effect of teaching about religion in public schools indicates that students taking the course showed statistically significant increases in passive tolerance, their willingness to refrain from discriminatory behavior, and active respect, the willingness to take action to counter discrimination. This research documents the circumstances that gave rise to the course and evaluates the course's effects using qualitative and quantitative evidence. It also connects the course to a larger research tradition in political science on the effects of civic education programs that promote liberal, democratic values.
(Not) Getting Religion: Has Political Science Lost Sight of Islam?
Authors: Tepe Sultan , Demirkaya Betul
Published: April 2011

In this analysis, we expand the debate on the place of religion in political science by using the predictions of Wald and Wilcox as our starting point. Following in their footsteps, we askhowpolitical scientists have studied Islam since 2002 and identify the studies on Islam and Muslims at the flagship conference of the discipline, the annual meeting of the American Political Science Association. We evaluate not only the quantity but also the approaches employed by these studies. In order to gauge the balancing of roles (or lack thereof) between the discipline and area studies, we also take a closer look at the Middle East Studies Association, the largest association focused on the Middle East, North Africa and the Islamic world and its annual meetings during the same period. Our findings suggest that, unless carefully addressed, the prevailing patterns are likely to result in a crippling knowledge gap among political scientists.
Constraints on glaciation in the middle Eocene (46–37 Ma) from Ocean Drilling Program (ODP) Site 1209 in the tropical Pacific Ocean
Authors: Dawber Caroline F. , Tripati Aradhna K.
Published: April 2011

The presence of glacial ice in the late middle Eocene has been vigorously debated. Recently published sedimentary data from the high latitudes is suggestive of episodic cooling events and near‐freezing sea surface temperatures during parts of the late middle Eocene. Constraints on ice volumes and the significance of excursions in open ocean foraminifera and seawater δ18O reconstructions are less clear, and there are few high‐resolution δ18O records. We present a new detailed record of benthic foraminiferal δ18O from Site 1209 that exhibits variations (Δδ18Obenthic) of 0.6‰–1.3‰. Different approaches have previously been used to interpret Δδ18Obenthic, including (1) an a priori assumption of a 50% contribution of temperature, similar to what is reconstructed for the Last Glacial Maximum–recent change; (2) applying Oligocene calibrations between apparent sea level (ASL) and Δδ18Obenthic; or (3) assuming temperature and seawater δ18O contributions can be partitioned through comparison with benthic Mg/Ca. Using assumption 1, the record from Site 1209 indicates changes in seawater δ18O of 0.3‰–0.7‰, equivalent to ∼33–72 m (m) of ASL (assuming mean ice δ18O of ∼−45‰). Using assumption 2 and two different end‐member calibrations, the δ18Obenthic record implies changes in ASL of 23–50 m or 50–108 m. The third approach yields changes in seawater δ18O of up to 0.6‰ to 1.4‰. We explore the compatibility of the results of each of these approaches with other studies that discuss evidence for ephemeral glaciations during the middle Eocene with variable ice storage at one or both poles.
A transpressional origin for the West Spitsbergen fold‐and‐thrust belt: Insight from analog modeling
Authors: Leever Karen A. , Gabrielsen Roy H. , Faleide Jan Inge , Braathen Alvar
Published: April 2011

The West Spitsbergen fold‐and‐thrust belt formed along the transform plate boundary between Greenland and the western Barents Sea during Paleocene‐Eocene breakup in the northern North Atlantic. Approximately 20–40 km margin‐perpendicular shortening accumulated in the belt has been attributed to transpression and strain partitioning in a restraining bend but also to head‐on collision. We have applied scaled analog tectonic modeling to test the former hypothesis. A pack of brittle quartz sand with a shallow thin layer of silicon putty was deformed by transpression at a 15° convergence angle by movement of a basal plate. The kinematics was quantified by means of digital particle image velocimetry. The result was a doubly vergent transpressional wedge, consisting of a steeply tapered retrowedge and a strongly internally deformed steeply tapered prowedge separated by a central strike‐slip zone and an adjacent low‐taper thin‐skinned fold‐and‐thrust belt. The doubly vergent wedge evolved through several kinematic phases. Three main stages were identified, namely, (1) initial distributed deformation, (2) development of an oblique doubly vergent wedge with progressive evolution of local strain partitioning along the marginal shear zones, and, finally, (3) a stage of full strain partitioning between a central strike‐slip zone and reverse displacement along marginal shear zones, with folding and thrusting in a thin‐skinned belt on the proside. The analog model convincingly reproduced the geometry and the kinematic evolution of the West Spitsbergen fold‐and‐thrust belt, supporting the hypothesis of its formation by strain partitioning in transpression with a small angle of convergence and significant lateral displacement.
Research Spotlight: Flood fatalities in Africa linked to settlement patterns
Authors: Tretkoff Ernie
Published: April 2011

Flood‐related fatalities in Africa have increased greatly over the past several decades. Has the intensity of flooding increased, perhaps owing to global climate changes? Or have human activity, population growth, and development patterns led to increased human vulnerability? To find out, Di Baldassarre et al. analyzed large data sets of floods in Africa. They considered trends in flooding as well as population dynamics and land use changes. (Geophysical Research Letters, doi:10.1029/2010GL045467, 2010)
Research Spotlight: What is the maximum sea level rise that coastal marshes can withstand?
Authors: Tretkoff Ernie
Published: April 2011

As sea level rises, many coastal marshes worldwide are predicted to submerge. What is the maximum rate of sea level rise that a coastal marsh can survive? Many previous studies of this question have assumed that the coastal wetland landscape is static, but, in fact, many coastal wetlands can adapt to sea level changes. For instance, in tidal marshes, increasing inundation leads to higher rates of sediment deposition, raising the elevation of the wetland and helping it withstand sea level rise. In salt marshes, higher sea levels can lead to increased growth of vegetation, which traps sediment and limits erosion. (Geophysical Research Letters, doi:10.1029/2010GL045489, 2010)
Research Spotlight: IRI model overestimated electron density in ionosphere
Authors: Tretkoff Ernie
Published: April 2011

Electron density in the Earth's ionosphere, which affects satellites and communications, is highly variable. Solar activity, which increases and decreases on an approximately 11‐year cycle, is a key driver of this ionospheric variability. The most recent solar minimum was unusually prolonged, leading to changes in the ionosphere. Did models accurately capture the effects of the long solar minimum on ionospheric electron density? To find out, Lühr and Xiong compared electron density predictions from the frequently used international reference ionosphere (IRI) model with in situ satellite measurements from Challenging Minisatellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE) for the years 2000–2009. (Geophysical Research Letters, doi:10.1029/2010GL045430, 2010)
Research Spotlight: Ozone‐destroying iodine measured in Arctic atmosphere
Authors: Tretkoff Ernie
Published: April 2011

Iodine in the atmosphere can destroy ozone and can also accelerate bromine‐catalyzed ozone depletion. Iodine has been measured in the Antarctic atmosphere at levels that cause significant ozone depletion. Mahajan et al. now report detailed measurements of iodine in the Arctic lower troposphere above Hudson Bay. They observed episodes of elevated levels of iodine monoxide as well as other iodine compounds. They suggest that the iodine monoxide probably originated from organoiodine compounds released from ice and seawater algae in areas of open water surrounded by sea ice in Hudson Bay. The emissions of these iodinated compounds will probably grow if sea ice cover in the Arctic continues to decrease. (Journal of Geophysical Research‐Atmospheres, doi:10.1029/2009JD013665, 2010)
The Florida Current: A Clean but Challenging Energy Resource
Authors: Hanson Howard P. , Bozek Alexandra , Duerr Alana E. S.
Published: April 2011

The patterns and overall magnitude of energy usage worldwide seem to preclude a single renewable alternative to traditional fossil fuel sources. Still, putting renewable resources to work where they exist, and thereby implementing a widely diversified portfolio of renewable energy recovery, offers the possibility of significantly reducing fossil fuel use on a regional basis. One such resource is the Florida Current, an oceanographic feature that has been the focus of intense study for many decades. Understanding its behavior on the time and space scales required to realize its energy potential, however, is still a work in progress, one that is challenged by a paucity of relevant data and by a range of sensitive environmental considerations.
Gulf Oil Spill Commission Report Calls for Major Drilling Safety Reforms
Authors: Showstack Randy
Published: April 2011

The BP Deepwater Horizon oil rig explosion and the resulting oil spill in the Gulf of Mexico last year were “foreseeable and preventable,” according to the report of a presidentially appointed commission, issued on 11 January, that recommended significant changes in U.S. government and industry practices to avoid future oil spill disasters. Among the recommendations of the National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling are that Congress and the Obama administration create an independent safety agency within the Department of the Interior (DOI) to oversee all aspects of offshore drilling safety and that the oil and gas industry establish a “safety institute” to develop and enforce safety standards.
Detachments in Oceanic Lithosphere: Deformation, Magmatism, Fluid Flow, and Ecosystems
Authors: Escartín J. , Canales J. P.
Published: April 2011

AGU Chapman Conference on Oceanic Detachments; Agros, Cyprus, 8–15 May 2010; Oceanic detachments are large‐offset normal faults along the flanks of mid‐ocean ridges. They represent a mode of accretion of the oceanic lithosphere that is fundamentally different from classical “magmatic” models, resulting in lithospheric composition and structure that are strikingly different from the Penrose model established 40 years ago of a layered magmatic crust. Oceanic detachments, which exhume deep lithosphere, forming oceanic core complexes (OCCs), are scientifically interesting because they represent tectonic windows to deep‐seated rocks and processes (mantle flow, melt generation and migration, strain localization, and crustal accretion) at mid‐ocean ridges; a fundamental process in the generation of oceanic lithosphere along sizeable sections of slow and ultraslow spreading centers; a system sustaining both long‐lived, high‐temperature hydrothermal circulation and low‐temperature, hydrogen‐rich, serpentinite‐related systems with their associated mineral deposits and ecosystems; a fault zone, containing weak hydrous alteration phases, that efficiently localizes strain, and that has associated footwall flexure and rotation; and a key to understanding continental core complexes as well as detachments at extensional, magma‐poor continental margins.
W. R. Peltier Receives 2010 Charles A. Whitten Medal
Authors: Dickey Jean O'Brien , Peltier W. R.
Published: April 2011

W. Richard Peltier was awarded the 2010 Charles A. Whitten Medal at the AGU Fall Meeting Honors Ceremony, held on 15 December 2010 in San Francisco, Calif. The medal is for “outstanding achievement in research on the form and dynamics of the Earth and planets.”
Research Spotlight: Extraordinary uplift of Yellowstone caldera
Authors: Tretkoff Ernie
Published: April 2011

In Yellowstone National Park, located in Wyoming, Montana, and Idaho, the Yellowstone caldera, which extends about 40 kilometers by 60 kilometers, began in 2004 a period of accelerated uplift, with rates of uplift as high as 7 centimeters per year. From 2006 to 2009 the uplift rate slowed. Global Positioning System (GPS) and interferometric synthetic aperture radar (InSAR) ground deformation measurements described byChang et al. show that in the northern caldera, uplift decreased from 7 centimeters per year in 2006 to 5 in 2008 and 2 in 2009. In the southwestern portion of the caldera, uplift decreased from 4 centimeters per year in 2006 to 2 in 2008 and 0.5 in 2009, demonstrating a spatial pattern of ground motion decrease from southwest to northeast along the caldera. (Geophysical Research Letters, doi:10.1029/2010GL045451, 2010)
Research Spotlight: What controls bedrock channel geometry?
Authors: Tretkoff Ernie
Published: April 2011

As rivers cut a path through bedrock, what influences the relationship between channel width, slope, and erosion rate? Data from naturally incising bedrock rivers show differing relationships among these parameters. For instance, while some studies show a strong inverse relationship between erosion rate and channel width, others show no such correlation. To explain the field data, Yanites and Tucker created a model of optimized channel geometry that accounts for water discharge, sediment supply, and base‐level fall. They found that including the erosion‐inhibiting effects of immobile sediment is necessary to explain the observed disparate relationships. Essentially, as more sediment is added to a river, the channel geometry must widen and steepen to transport the supplied sediment and continue eroding bedrock at the rate of base‐level fall. For channels carrying significant bed load, they found that channel width can be the primary morphological control on the erosive potential of the river, a prediction matched by field data. Further, trade‐offs between increasing sediment supply (which widens the channel) and erosion rate (which narrows the channel) can generate rivers with no relationship between channel width and erosion rate. The model helps explain the conflicting field observations of controls of channel geometry and could contribute to improved understanding of landscape evolution. (Journal of Geophysical Research‐Earth Surface, doi:10.1029/2009JF001601, 2010)
Research Spotlight: New method to estimate daily flow rates at streams that lack gauges
Authors: Kumar Mohi
Published: April 2011

Records of daily streamflow rates can help scientists estimate future runoff volumes or determine whether fish and other aquatic species have enough water to survive an upcoming season. Many streams are monitored by gauges; however, the sheer number of catchments throughout the United States makes it impractical to have instruments at every stream. As a result, scientists and water resources managers often face the problem of needing to know flow rates within ungauged streams. Archfield and Vogel have developed a method to estimate such flow rates. Using southern New England as a case study, the authors first selected a gauged stream and then, using statistical methods, compared the record of daily streamflow rates from that stream spanning the past 50 years to 27 other streams in the area. On the basis of this comparison, they made a map that marked out the region surrounding their stream where rates at the gauged stream were correlated to other streams about 98% of the time. The researchers then drew borders around the area where their stream matched other streams 95% of the time. Through a series of decreasing percentages of correlation, the authors built a spatial view of how closely their reference‐gauged stream matched other streams in the region. (Water Resources Research, doi:10.1029/2009WR008481, 2010)
Research Spotlight: Oscillation of the locations of Saturn's auroral ovals
Authors: Tretkoff Ernie
Published: April 2011

Using images from the Hubble Space Telescope, Nichols et al. observed oscillations in the locations of Saturn's northern and southern auroral ovals. Both auroral ovals' positions oscillate 1°–2° between dawn and dusk. While the southern auroral oval oscillation had been previously observed, the present observation, made during Saturn's 2009 equinox, is the first one that indicates that the location of the northern auroral oval oscillates with similar amplitude. The researchers also found that the locations of the auroral ovals oscillate with periods close to the rotation periods of radio emissions known as Saturn kilometric radiation (SKR). In a related paper, Gurnett et al. (Geophys. Res. Lett., 37, L24101, doi:10.1029/2010GL045796, 2010) observed changes in the rotational modulation rate of the SKR that could be controlled by changes in the planet's magnetosphere. Magnetosphere effects could cause shifting of the auroral ovals as well. (Geophysical Research Letters, doi:10.1029/2010GL045818, 2010)
Research Spotlight: Interpreting parameters in water transit time distribution
Authors: Tretkoff Ernie
Published: April 2011

The distribution of the time it takes water or solute molecules to flow through a drainage basin, or catchment, can be useful for understanding variability, storage capacity, and pollutant transport in catchments and for comparing hydrology in different catchments. A statistical distribution called the gamma distribution has been shown to be a suitable representation of transit time distribution in hydrological tracer studies. However, the gamma distribution involves two parameters that have not had a clear physical interpretation when used as a catchment transit time distribution. To explore a physical interpretation for these parameters, Hrachowitz et al. analyzed long‐term tracer and precipitation data in three different catchments in the Scottish Highlands. They found that one parameter had little variation in time and did not vary along with meteorological/climatic conditions such as precipitation intensities but instead was related to features of the catchment landscape such as the hydrological characteristics of the soils and drainage density. The other parameter was found to vary in time and was controlled largely by precipitation intensity. Using this information, the authors calculated time‐variant transit time distributions, which they suggest provide more detailed and useful information about the timing and magnitude of tracer fluxes. This could be especially useful in representing the effects of contaminants in sensitive catchments. (Water Resources Research, doi:10.1029/2010WR009148, 2010)
Research Spotlight: Spooky action at a distance, for earthquakes
Authors: Schultz Colin
Published: April 2011

On 27 February 2010 a magnitude 8.8 earthquake rocked millions of Chileans from their slumber, but the South American people weren't the only ones so affected. New research by Peng et al. suggests that the trembling off the Chilean coast could have triggered a swarm of shallow earthquakes nearly 10,000 kilometers away in central California. The team identified four earthquakes with magnitudes of 2 or higher, with the largest of the group being a M 3.5 quake that rattled the Coso geothermal field. The affected region is plagued by small earthquakes, but when the authors calculated the chance of a swarm so neatly following the Chilean earthquake, they inferred that the two seismic events were probably connected. The authors also saw a cluster of deep, low‐frequency earthquakes along the Parkfield‐Cholame section of the San Andreas Fault that also appeared to be influenced by the Chilean event. The researchers suggest that the timing of the California earthquakes was affected by the arrival of Love waves—horizontal surface movement that would have traveled out from the epicenter of the Chilean earthquake, pushing already stressed faults over the edge. (Geophysical Research Letters, doi:10.1029/2010GL045462, 2010)
Research Spotlight: Potential pathways of radioactive contaminants to surface waters
Authors: Kumar Mohi
Published: April 2011

From the 1940s to the end of the Cold War, the U.S. Department of Energy maintained production facilities for manufacturing nuclear weapons along the Columbia River north of Richland, Wash. Known as the Hanford Site, the Rhode Island–sized area contains more than 53 million gallons of radioactive waste and is the location of a massive environmental cleanup. Of particular concern is that when the facility was active, fluids containing 33–59 tons of uranium were discharged into the shallow subsurface aquifer underneath Hanford. Studies suggest that this pollution is pervasively moving with the groundwater in the direction of the Columbia River. (Water Resources Research, doi:10.1029/2010WR009110, 2010)
Research Spotlight: North and south components of Saturn's radio emissions reversed
Authors: Tretkoff Ernie
Published: April 2011

Saturn is known to emit intense radio emissions at kilometer wavelengths from its auroral regions. Observations in recent years found that the Saturn kilometric radiation (SKR) emission from the northern auroral region has a clocklike modulation with a period of about 10.6 hours, while the SKR emission from the southern auroral region has a period of about 10.8 hours. Analyzing more recent observations from the Cassini spacecraft, Gurnett et al. have now found that the rotational modulation rates of the southern and northern components reversed shortly after Saturn's equinox on 11 August 2009, so that the southern hemisphere SKR now has the shorter rotation period. They also analyzed data from the Ulysses spacecraft to show that a similar reversal occurred during the previous equinox, in November 1995. (Geophysical Research Letters, doi:10.1029/2010GL045796, 2010)
Research Spotlight: New evidence could let supereruption off the hook
Authors: Schultz Colin
Published: April 2011

It's a case of forensic analysis on the grandest scale: the possible near‐extinction of the entire human race at the hands of one volcanic supereruption. The Younger Toba Tuff (YTT) eruption 74,000 years ago has been accused of blanketing the sky with sulfate aerosols and driving the world into a long‐lasting winter. In a new study,Timmreck et al. have given the Sumatran volcano a climatological alibi. The authors used a global circulation model to simulate the YTT eruption, including for the first time an analysis of the small‐scale interactions between sulfate particles. Sulfate particles in the upper atmosphere strongly reflect incoming solar radiation, which has a cooling effect on the Earth. (Geophysical Research Letters, doi:10.1029/2010GL045464, 2010)
Research Spotlight: Evidence for water ice near the Martian equator
Authors: Schultz Colin
Published: April 2011

When one looks for water on Mars, the most obvious targets are the ice‐capped polar regions. However, Shean found what appears to be buried water ice or an ice‐debris mix within 38 craters in the Sinus Sabaeus region near the Martian equator. While previous research has suggested that water was historically present near the equator, Mars's current climate is supposed to be inhospitable to equatorial water ice. Using satellite imagery, the author found material at the bottom of equatorial craters that is visually similar to material thought to be buried ice found elsewhere on Mars, especially in midlatitude craters (30°–60°N/S). He also found 30 additional craters where this material has been partially or completely removed, leaving traces that suggest it is composed of buried ice. (Geophysical Research Letters, doi:10.1029/2010GL045181, 2010)
Research Spotlight: Tectonic plates relocked after 2005 earthquake in northeastern Japan
Authors: Tretkoff Ernie
Published: April 2011

In August 2005 a magnitude 7.2 earthquake shook northeastern Japan. The quake occurred on the boundary of the North American plate and the Pacific plate off Miyagi prefecture. Earthquakes with a magnitude of about 7.5 have been occurring in this area approximately every 37 years. Sato et al. used seafloor geodetic observations from a combination of Global Positioning System (GPS) and acoustic measurements to detect seafloor movements during and after the earthquake. They focused on the movement of a seafloor reference point located about 10 kilometers east of the epicenter of the 2005 quake. (Geophysical Research Letters, doi:10.1029/2010GL045689, 2011)
Research Spotlight: Improving estimates of water volume in mountain snowfall
Authors: Schultz Colin
Published: April 2011

Spring snowmelt can sustain life, power hydroelectric energy generation, or be a source of devastating floods. A major issue for those trying to prepare for the melt season is that what is easiest to measure—the area of land covered in snow—does not necessarily yield a good estimate of how much water is locked up in the powder: Snow does not fall evenly across landscapes, and the low‐resolution microwave images that give water volume estimates miss important spatial variations.Kolberg and Gottschalk sought a new approach for estimating the volume of water locked up in their study area, a mountainous region in the south of Norway. Snowfall in the mountains is highly influenced by the terrain, so the distribution tends to be similar from one year to the next. This consistency allowed the authors to use moderate‐resolution satellite images showing the area covered in snow to calibrate a model that uses precipitation distribution observations to calculate runoff patterns for the region. The authors used the average from 5 years of observations of snowmelt patterns to predict when, where, and how much snow would melt and run off in a sixth year. (Water Resources Research, doi:10.1029/2008WR007617, 2010)
Research Spotlight: Buoyancy explains asymmetry along mid‐ocean ridges
Authors: Tretkoff Ernie
Published: April 2011

Oceanic crust is formed at mid‐ocean ridges, the seam‐like boundaries between divergent tectonic plates that can extend more than 50,000 kilometers in length. This crust is made of solidified magma that has segregated from the upwelling, partially molten mantle below. Geographic variation in plate divergence rate and mantle temperature can account for some differences between segments of the ridge, but other features of mid‐ocean ridges have not been explained. For instance, seismic tomography indicates that some mid‐ocean ridges have a distribution of mantle upwelling and melting that is asymmetrical across the ridge axis. What accounts for this asymmetry? (Geochemistry, Geophysics, Geosystems, doi:10.1029/2010GC003282, 2010)
Research Spotlight: More accurate measurements of total solar irradiance
Authors: Tretkoff Ernie
Published: April 2011

Radiation from the Sun is the dominant source of energy input to the Earth's climate system; even small variations in solar irradiance can produce noticeable climate changes on global and regional scales. Determining how much of the observed global change can be attributed to variations in the Sun's output and how much can be attributed to human or other influences requires an accurate record of solar irradiance. Measurements of solar irradiance made by the Total Irradiance Monitor (TIM) on NASA's Solar Radiation and Climate Experiment (SORCE) satellite give a value of total solar irradiance that is significantly lower than previously accepted values. Kopp and Lean show that this new, lower value is more accurate than measurements made using older instruments. They used laboratory studies and satellite calibrations to diagnose and quantify error sources on TIM and other space‐based solar radiometers and found that earlier radiometers measured higher values of solar irradiance because they included scattered instrument light in their signals, while the different optical design of the TIM radiometer reduces this spurious signal and acquires more accurate measurements. They also show that TIM's high stability gives improved agreement with models estimating solar variability, concluding that this new instrument provides the most accurate value of solar irradiance and helps improve estimates of the Sun's influence on climate. (Geophysical Research Letters, doi:10.1029/2010GL045777, 2011)
Research Spotlight: Climate commitment in an uncertain world
Authors: Tretkoff Ernie
Published: April 2011

Even if humans immediately ceased emitting carbon dioxide (CO2) and other greenhouse gases, the planet would continue to warm, mainly due to thermal inertia of the world's oceans. This “climate commitment” has been of interest recently for both science and policy because it provides a measure of the minimum climate change the planet will face given human activity that has already occurred. Several studies have looked at what would happen if human emission of CO2 were halted, but these studies have overlooked the role of aerosols and non‐CO2 greenhouse gases such as methane and nitrous oxide, whichArmour and Roe include in a new study. If human emission stopped, atmospheric aerosols, which cool the planet by blocking light from the surface, would fall to preindustrial levels within weeks. However, non‐CO2 greenhouse gases would remain in the atmosphere for decades to centuries, and elevated levels of CO2 would persist for millennia. (Geophysical Research Letters, doi:10.1029/2010GL045850, 2011)
Research Spotlight: River‐to‐lake connectivity and habitat diversity
Authors: Tretkoff Ernie
Published: April 2011

The 45,000 lakes in the Mackenzie River delta, Canada, represent an especially diverse aquatic habitat compared to lakes in surrounding Arctic areas. River‐to‐lake connectivity could play a role in this diversity, as river water entering lakes replenishes nutrients and affects water transparency. Lesack and Marsh sought to better understand how river‐to‐lake connectivity affects biodiversity in the region. Using 40 years of data on water levels in the delta combined with a floodplain geometry model, they estimated the volumes of river water added to lake water during the annual flood peak for nine lakes at different elevations. (Water Resources Research, doi:10.1029/2010WR009607, 2010)
Research Spotlight: China's lakes changed dramatically in recent decades
Authors: Tretkoff Ernie
Published: April 2011

Significant changes have taken place in the number and size of China's lakes over the past several decades. To create a comprehensive picture of these changes over all of China, Ma et al. combined data from a wide variety of sources, including satellite imagery and maps. They compared data from the 1960s to the 1980s, before China's rapid development and industrialization, with data from 2005 and 2006. The authors found that over that time period the total number of lakes with area greater than 1 square kilometer decreased from 2928 to 2693. The total surface area of Chinese lakes declined by 13% over that time period. In addition, 243 lakes vanished, mainly in the northern provinces and some southern provinces, while 60 new lakes appeared, mainly in the Tibetan Plateau region. (Geophysical Research Letters, doi:10.1029/2010GL045514, 2010)
Research Spotlight: Political bias in water quality monitoring
Authors: Schultz Colin
Published: April 2011

When legislators put out a call for scientific information, they expect the response to be based on the most stringent data possible. But when the information comes from a large monitoring network—like water quality measurements across Europe—the results could be based on politics as much as on science. In the first study of its kind, Beck et al. used statistical methods to track the development of Europe's water‐monitoring system from 1965 to 2004 in an attempt to tease out how the placement of monitoring stations might be influenced by economic and political pressures rather than by environmental needs. Some trends were expected: Monitoring increased with income, population density, and democracy and showed a general increase over time. Monitoring was also higher when a river crossed international boundaries than when it flowed through one nation alone. Another trend, however, ran against the researchers' assumptions: Being a member of the European Union (EU) was related to lower monitoring densities. The authors suspected that countries that were not early members of the EU may have tried to curry favor with their neighbors by increasing their monitoring programs, while other governments felt no such pressure. (Water Resources Research, doi:10.1029/2009WR009065, 2010)
Research Spotlight: Narwhals document continued warming of Baffin Bay
Authors: Kumar Mohi
Published: April 2011

Baffin Bay, situated between northern Greenland and Canada, is a major gateway between waters from the North Atlantic and Arctic oceans. Dynamics within the bay help govern how much water from the Arctic flows south and sinks to form North Atlantic Deep Water, a deep current that drives ocean circulation on a global scale. Unfortunately, monitoring the deep reaches of Baffin Bay throughout the year is difficult—most oceanographic data are collected in the summer when the area is ice free. To overcome this inability to collect data in harsh winter conditions, Laidre et al. hit upon a novel solution: mounting instruments on narwhals to collect temperature and depth data. Narwhals, a top predator in this frigid ecosystem, make annual migrations from summering grounds in the Canadian High Arctic and western Greenland to wintering grounds in the dense offshore pack ice of Baffin Bay. Moreover, narwhals, which rank among the deepest‐diving whales in the world, dive extensively and repeatedly to depths exceeding 1800 meters under pack ice to reach their major food source, the flatfish that swarm on the seafloor of Baffin Bay. Narwhal dives are nearly vertical, making this whale an ideal platform on which to mount surveying instruments. (Journal of Geophysical Research‐Oceans, doi:10.1029/2009JC005820, 2010)
Research Spotlight: Climate response to melting of the West Antarctic Ice Sheet
Authors: Tretkoff Ernie
Published: April 2011

The West Antarctic Ice Sheet (WAIS) could collapse in the future as the rising sea level and warming climate destabilize the sheet. Previous studies have shown that melting of WAIS could contribute to several meters of global sea level rise over the next few centuries. Some studies have pointed to evidence that WAIS has collapsed in the past during previous interglacial periods, which could give clues to what might happen in the future. To gain additional insight into how the Earth's climate would respond to a collapse of WAIS, Menviel et al. simulated the effects on global climate and the carbon cycle of a massive meltwater discharge from the collapse of the ice sheet. They found that a large meltwater discharge into the Southern Ocean would lead to a substantial cooling of the Southern Ocean, causing a northward expansion of the sea ice margin. Southern Hemisphere westerly winds would intensify. Furthermore, the formation of cold Antarctic Bottom Water would be suppressed, and subsurface warming would take place in areas where Antarctic Bottom Water is formed under present‐day conditions. This subsurface warming would lead to positive feedback that would accelerate the melting of the ice sheet. (Paleoceanography, doi:10.1029/2009PA001892, 2010)
Research Spotlight: Modeling the giant impact crater on asteroid 4 Vesta
Authors: Tretkoff Ernie
Published: April 2011

The asteroid 4 Vesta is one of the largest rocky bodies in the asteroid belt, with a mean diameter of about 530 kilometers. An enormous impact crater, with a diameter of about 460 kilometers and a depth of about 13 kilometers, covers almost half of the asteroid's southern hemisphere. This summer, NASA's Dawn mission will orbit Vesta. To provide a framework for interpreting some of the expected observations of landforms, Jutzi and Asphaug modeled the formation of the impact crater, which was probably created by a collision with an approximately 50‐kilometer‐diameter object traveling at about 5 kilometers per second. (Geophysical Research Letters, doi:10.1029/2010GL045517, 2011)
Research Spotlight: Simulating ocean carbon storage during the Last Glacial Maximum
Authors: Tretkoff Ernie
Published: April 2011

During the cold period of the Last Glacial Maximum, about 21,000 years ago, atmospheric carbon dioxide (CO2)concentration was about 190 parts per million, compared to 280 parts per million in the preindustrial era and about 385 parts per million today. While less carbon was stored in the atmosphere during the Last Glacial Maximum, the oceans probably held more carbon. Atmospheric carbon isotope ratios (δ13C) were similar to today's values, but the oceans had a steeper surface‐to‐deep gradient in δ13C. Previous simulations had trouble simulating simultaneously atmospheric CO2 levels and oceanic δ13C. To reconcile both data, Bouttes et al. ran simulations including a new combination of three mechanisms: brine‐induced ocean stratification, stratification‐dependent diffusion, and iron fertilization. Including these effects made it possible to account for the recorded glacial carbon cycle changes, reconciling the Last Glacial Maximum δ13C values and atmospheric CO2 levels. (Geophysical Research Letters, doi:10.1029/2010GL044499, 2011)
Research Spotlight: Changing atmospheric chemistry with the swing of an axe
Authors: Schultz Colin
Published: April 2011

When a tree is cut down, carbon that has been stored for tens, hundreds, or even thousands of years is released to the environment. In addition, felling that tree slightly alters the wind's path through the woods. If enough forest is cleared, significant changes can be seen in weather patterns and the global carbon cycle. However, the forest is more than a box of carbon and a wind screen. In a new study,Ganzeveld et al. used a climate model that takes into account atmospheric chemistry and gas exchanges at the Earth's surface. The researchers wanted to understand the long‐term effects of land use change, which, in addition to carbon cycle and weather pattern effects, can also affect concentrations of various reactive trace gases in the atmosphere, including greenhouse gases such as methane and ozone. Using a land cover and land use projection for the year 2050, the authors find that Earth should expect higher concentrations of ground‐level ozone and an increase in the oxidizing capacity of the atmosphere. As deforestation continues, the amount of turbulence in the lower atmosphere will decrease, reducing mixing and leading to a buildup of ground‐level ozone. (Journal of Geophysical Research‐Atmospheres, doi:10.1029/2010JD014041, 2010)
Research Spotlight: No tipping point for Arctic Ocean ice
Authors: Schultz Colin
Published: April 2011

Declines in the summer sea ice extent have led to concerns within the scientific community that the Arctic Ocean may be nearing a tipping point, beyond which the sea ice cap could not recover. In such a scenario, greenhouse gases in the atmosphere trap outgoing radiation, and as the Sun beats down 24 hours a day during the Arctic summer, temperatures rise and melt what remains of the polar sea ice cap. The Arctic Ocean, now less reflective, would absorb more of the Sun's warmth, a feedback loop that would keep the ocean ice free. However, new research by Tietsche et al. suggests that even if the Arctic Ocean sees an ice‐free summer, it would not lead to catastrophic runaway ice melt. The researchers, using a general circulation model of the global ocean and the atmosphere, found that Arctic sea ice recovers within 2 years of an imposed ice‐free summer to the conditions dictated by general climate conditions during that time. Furthermore, they found that this quick recovery occurs whether the ice‐free summer is triggered in 2000 or in 2060, when global temperatures are predicted to be 2°C warmer. (Geophysical Research Letters, doi:10.1029/2010GL045698, 2011)
Research Spotlight: Exploring storage stability for underground carbon sequestration
Authors: Schultz Colin
Published: April 2011

With the world turning on to concerns about global climate change, strategies are being weighed to combat rising atmospheric carbon dioxide levels. One proposed solution is geologic carbon sequestration—storing liquid carbon dioxide deep underground. However, for long‐term underground storage of carbon dioxide, stability of the underground reservoirs is a major concern. Selecting the best storage locations requires a detailed understanding of the rock's internal structure. (Geophysical Research Letters, doi:10.1029/2010GL045875, 2011)