bluuebunny/crossref_metadata_2025 huggingface dataset:
The social and psychological costs of punishing
Authors: Adams Gabrielle S. , Mullen Elizabeth
Published: January 2012

We review evidence of the psychological and social costs associated with punishing. We propose that these psychological and social costs should be considered (in addition to material costs) when searching for evidence of costly punishment “in the wild.”
The punishment that sustains cooperation is often coordinated and costly
Authors: Bowles Samuel , Boyd Robert , Mathew Sarah , Richerson Peter J.
Published: January 2012

Experiments are not models of cooperation; instead, they demonstrate the presence of the ethical and other-regarding predispositions that often motivate cooperation and the punishment of free-riders. Experimental behavior predicts subjects' cooperation in the field. Ethnographic studies in small-scale societies without formal coercive institutions demonstrate that disciplining defectors is both essential to cooperation and often costly to the punisher.
Weak reciprocity alone cannot explain peer punishment
Authors: Casari Marco
Published: January 2012

The claims about (1) the lack of empirical support for a model of strong reciprocation and (2) the irrelevant empirical role of costly punishment to support cooperation in the field need qualifications. The interpretation of field evidence is not straightforward, and other-regarding preferences are also likely to play a role in the field.
Retaliation and antisocial punishment are overlooked in many theoretical models as well as behavioral experiments
Authors: Dreber Anna , Rand David G.
Published: January 2012

Guala argues that there is a mismatch between most laboratory experiments on costly punishment and behavior in the field. In the lab, experimental designs typically suppress retaliation. The same is true for most theoretical models of the co-evolution of costly punishment and cooperation, which a priori exclude the possibility of defectors punishing cooperators.
Blood, sex, personality, power, and altruism: Factors influencing the validity of strong reciprocity
Authors: Ferguson Eamonn , Corr Philip
Published: January 2012

It is argued that the generality of strong reciprocity theory (SRT) is limited by the existence of anonymous spontaneous cooperation, maintained in the absence of punishment, despite free-riding. We highlight how individual differences, status, sex, and the legitimacy of non-cooperation need to be examined to increase the internal and ecological validity of SRT experiments and, ultimately, SRT's external validity.
The social costs of punishment
Authors: van den Berg Pieter , Molleman Lucas , Weissing Franz J.
Published: January 2012

Lab experiments on punishment are of limited relevance for understanding cooperative behavior in the real world. In real interactions, punishment is not cheap, but the costs of punishment are of a different nature than in experiments. They do not correspond to direct payments or payoff deductions, but they arise from the repercussions punishment has on social networks and future interactions.
Understanding the research program
Authors: Henrich Joseph , Chudek Maciej
Published: January 2012

The target article misunderstands the research program it criticizes. The work of Boyd, Richerson, Fehr, Gintis, Bowles and their collaborators has long included the theoretical and empirical study of models both with andwithoutdiffuse costly punishment. In triaging the situation, we aim to (1) clarify the theoretical landscape, (2) highlight key points of agreement, and (3) suggest a more productive line of debate.
When the strong punish: Why net costs of punishment are often negligible
Authors: von Rueden Christopher R. , Gurven Michael
Published: January 2012

In small-scale societies, punishment of adults is infrequent and employed when the anticipated cost-to-benefit ratio is low, such as when punishment is collectively justified and administered. In addition, benefits may exceed costs when punishers have relatively greater physical and social capital and gain more from cooperation. We provide examples from the Tsimane horticulturalists of Bolivia to support our claims.
Emotional availability: Concept, research, and window on developmental psychopathology
Authors: Biringen Zeynep , Easterbrooks M. Ann
Published: January 2012

The construct of emotional availability (EA) refers to the capacity of a dyad to share an emotional connection and to enjoy a mutually fulfilling and healthy relationship. The EA Scales were designed to assess multiple components of a relationship from the perspective of both partners. The four caregiver components include sensitivity, structuring, nonintrusiveness, and nonhostility; two scales measure the child's responsiveness to the caregiver and involvement of the caregiver. We describe the EA construct and introduce the papers in this issue, focusing on the contributions of this Special Section to a developmental psychopathology framework.
A developmental psychopathology perspective on emotional availability research: Current trends and challenges
Authors: Beeghly Marjorie
Published: January 2012

Studies using the Emotional Availability Scales have burgeoned in the past decade. The collection of papers included in this Special Section represents the latest innovations in research with this paradigm. Consistent with a developmental psychopathology perspective, these papers evaluate emotional availability in a variety of typical, at-risk, international, and intergenerational samples of children and caregivers, with many utilizing longitudinal designs or employing measures from multiple levels of analysis. One study begins to translate findings from this body of research into a promising intervention program. Although further growth and refinement in research with this paradigm is needed, the results to date begin to place the construct of emotional availability into a complex, dynamic biopsychosocial context, and promise to inspire a new generation of studies. In this commentary, some of the key contributions and challenges of this collection of studies are highlighted using a developmental psychopathology framework.
Emotional availability: Research advances and theoretical questions
Authors: Oppenheim David
Published: January 2012

The commentary opens by highlighting the contribution of the Emotional Availability Scales (EAS) in providing developmental researchers with a clinically sensitive and reliable assessment of the emotional quality of caregiver–child interactions that takes into consideration their coregulated nature. The numerous studies that have used the EAS attest to their usefulness and to the way they balance complexity and attention to emotional nuances with clarity. Several issues with regard to the EAS are discussed subsequently. First, I propose that looking at patterns of the EA scales might be a way to capture the quality of each dyad's emotional dialogue. Second, I suggest that the description of attachment research as concerned almost exclusively with the regulation of distress is inaccurate, in light of Ainsworth's broad assessment of naturalistic home observations. Third, I raise the possibility that additional specialized coding systems beyond the EAS may be needed for predicting certain specific psychopathological outcomes (e.g., disorganized attachment). Fourth, I propose that it is important to explore cross-culturally the meaning of the behaviors on which the EAS focus, rather than assume cross-cultural equivalence. Fifth and finally, I point out the importance of placing the EAS in the context of the existing literature on early intervention and treatment.
Interaction of serotonin transporter linked polymorphic region and childhood neglect on criminal behavior and substance use for males and females
Authors: Vaske Jamie , Newsome Jamie , Wright John Paul
Published: January 2012

Childhood neglect has been cited as a risk factor for later substance abuse and criminal behavior. However, a large body of literature shows that a substantial percentage of neglected and abused individuals do not go on to abuse substances or engage in criminal behavior. The current study investigates whether a genetic variant (serotonin transporter linked polymorphic region [5-HTTLPR]) in the 5-hydroxytryptamine (5-HTT) gene moderates the effect of childhood neglect on alcohol use problems, marijuana use, and criminal behavior. Data from the National Longitudinal Study of Adolescent Health shows that 5-HTTLPR conditions the effect of neglect on marijuana use for females, but not for males. Findings also reveal a significant gene–environment correlation between 5-HTTLPR and neglect for females only. These results suggest that 5-HTTLPR is associated with an increased risk of neglect for females, and it also increases neglected females’ risk of abusing marijuana.
Executive functioning, cortisol reactivity, and symptoms of psychopathology in girls with premature adrenarche
Authors: Sontag-Padilla Lisa M. , Dorn Lorah D. , Tissot Abbigail , Susman Elizabeth J. , Beers Sue R. , Rose Susan R.
Published: January 2012

The study examined the interaction between early maturational timing (measured by premature adrenarche [PA]) and executive functioning and cortisol reactivity on symptoms of psychopathology. The study included 76 girls aged 6 through 8 years (mean = 7.50,SD= 0.85) with PA (n= 40) and on-time adrenarche (n= 36). Girls completed a battery of psychological and neuropsychological tests and blood sampling for cortisol. Parents completed the Child Behavior Checklist. The results demonstrated that girls with PA with lower levels of executive functioning had higher externalizing and anxious symptoms compared to other girls. In addition, girls with PA who demonstrated increases in serum cortisol had higher externalizing symptoms than those with stable patterns. Finally, girls with PA who demonstrated decreases in cortisol reported higher depressive symptoms. The findings from this study provide important information concerning the impact of cognitive functioning and stress reactivity on adjustment to early maturation in girls with PA. The results of this research may inform screening and intervention efforts for girls who may be at greatest risk for emotional and behavioral problems as a result of early maturation.
Change and reciprocity in adolescent aggressive and rule-breaking behaviors and parental support and dysfunctional discipline
Authors: de Haan Amaranta D. , Prinzie Peter , Deković Maja
Published: January 2012

This study examined how the development of aggressive/rule-breaking behaviors (9–17 years) is related to the development of overreactive and warm parenting, and explored gender differences in development and interrelations. Externalizing was assessed using combined mother/father reports of the Child Behavior Checklist (N= 516). Overreactivity was assessed using self-reports of the Parenting Scale; warmth was measured using self-reports of the Parenting Practices Questionnaire. All constructs were assessed three times across 6 years. The interrelated development of externalizing and parenting was examined by cohort-sequential multigroup latent growth models. Timing of effects was investigated using multigroup cross-lagged models. The results from latent growth models suggest that boys and girls change similarly in the extent to which they show externalizing behaviors, and indicate that mothers and fathers show somewhat different parenting toward boys than girls. No gender differences were found for interrelations between externalizing and parenting. Initial levels of aggression were related to changes in overreactivity and warmth, and vice versa. Changes in externalizing were related to changes in parenting. Cross-lagged models showed that relations between overreactivity and aggression/rule breaking were reciprocal. Together, results from this study show that adolescent externalizing and parenting affect each other in important ways, regardless of the gender of the child or the parent.
Reconciling productivity with protection of the environment: Is temperate agroforestry the answer?
Authors: Smith Jo , Pearce Bruce D. , Wolfe Martin S.
Published: January 2012

Meeting the needs for a growing world population calls for multifunctional land use, which can meet the multiple demands of food and fuel production, environmental and biodiversity protection, and has the capacity for adaptation or resilience to climate change. Agroforestry, a land-use system that integrates trees and shrubs with crops and/or livestock production, has been identified by the International Assessment of Agricultural Knowledge, Science and Technology for Development (IAASTD) as a ‘win–win’ approach that balances the production of commodities (food, feed, fuel, fiber, etc.) with non-commodity outputs such as environmental protection and cultural and landscape amenities. Evidence is now coming to light that supports the promotion of agroforestry in temperate developed countries as a sustainable alternative to the highly industrialized agricultural model with its associated negative environmental externalities. This paper reviews this evidence within the ‘ecosystem services’ framework to evaluate agroforestry as part of a multifunctional working landscape in temperate regions. Establishing trees on agricultural land can help to mitigate many of the negative impacts of agriculture, for example by regulating soil, water and air quality, supporting biodiversity, reducing inputs by natural regulation of pests and more efficient nutrient cycling, and by modifying local and global climates. The challenge now lies in promoting the adoption of agroforestry as a mainstream land use through research, dissemination of information and policy changes.
Economic impacts of IPM sampling methods for collards
Authors: Ferrer Myra Clarisse , Hammig Michael
Published: January 2012

Integrated pest management (IPM) has been very successful in directing farming to a more environment-friendly production. It is a great tool for producers in transition to organic farming. However, the extent of its economic impact is not well understood by farmers. This study looks at the amount of savings and potential market profitability of using IPM in South Carolina collard production considering alternative scouting methods. Scouting is an essential part of IPM that is usually ignored. This analysis presents a comparative assessment of the merits of conventional sampling (CS) and binomial sequential scouting method (SSM). SSM is a recently developed scouting system for traditionally operated collard farms that is geared toward a more economical execution of scouting without forfeiting the effectiveness of the process. Financial analytical tools, specifically costs and returns methods and sensitivity analysis on prices, were utilized to determine the economic advantages or disadvantages of the two methods. Outcomes indicate that both scouting methods would result in cost savings if used on traditionally operated farms. Particularly, the cost savings per hectare generated from IPM with SSM [3.62% of total cost (TC) and 3.91% of total variable cost (TVC)] is higher than the cost savings from IPM with CS (2.91% of TC and 3.15% of TVC). The difference in cost savings between IPM with CS and IPM with SSM basically came from the less scouting time of SSM that entailed lower labor cost for the farm. Therefore, to attain maximum profitability potential, using IPM with the SSM is a better option. Some may conjecture that the cost savings were insignificant due to the low percentages in cost savings. However, its importance is evident at the potential savings per farm and at the aggregate/state level.
Optical properties of sea ice in Liaodong Bay, China
Authors: Xu Zhantang , Yang Yuezhong , Wang Guifen , Cao Wenxi , Li Zhijun , Sun Zhaohua
Published: January 2012

Many industrial, agricultural, and residential areas surrounding Liaodong Bay are responsible for much of the particulate matter (PM) and colored dissolved organic matter (CDOM) found in the sea ice in the bay. Understanding the optical properties of “dirty” sea ice is important for analyzing remote sensing data and calculating energy balances. We designed a hyperspectral radiation instrument to observe the optical properties of sea ice. The results show that albedo peaks ranged from 0.3 to 0.85 and that the peaks shifted to a longer wavelength for high PM and CDOM concentrations. The absorption and scattering coefficients for sea ice were obtained. The bulk absorption coefficient shows that bulk absorption is primarily determined by PM and CDOM at shorter wavelengths, while pure ice and brine pockets become more important at longer wavelengths. Scattering coefficients for sea ice ranged from 197 to 1072 m−1, and showed consistent variations with gas bubble and brine pocket concentrations. The effects of PM and CDOM on the bulk absorption coefficient of sea ice were studied. At 440 nm, particulates accounted for 55–98% and CDOM accounted for 2–37% of the bulk absorption. Ratios between particulate absorption and bulk absorption for sea ice were almost constant from 400 to 550 nm, and began to decrease sharply for wavelengths >550 nm. Ratios between CDOM and bulk absorption decreased almost linearly with increasing wavelength.
First synoptic analysis of volcanic degassing in Papua New Guinea
Authors: McCormick Brendan T. , Edmonds Marie , Mather Tamsin A. , Carn Simon A.
Published: January 2012

We report the first satellite‐based survey of volcanic sulphur dioxide (SO2) degassing in Papua New Guinea, using Ozone Monitoring Instrument (OMI) data. OMI is sensitive to low‐level passive degassing. These observations are useful for volcano monitoring, hazard assessment (particularly aviation hazard) and assessment of arc geochemical budgets and are of immense value in remote regions with little ground‐based instrumentation, such as Papua New Guinea. We identify Bagana, Manam, Rabaul, Ulawun and Langila as the active sources of volcanic SO2 in Papua New Guinea, with Bagana being the largest source. We present an OMI SO2 time series for 2005–2008 and a total detected regional output of ∼1.8 × 109 kg SO2. About 40% of emissions were released by major eruption events at Manam (January 2005), Bagana (June 2006) and Rabaul (October 2006). Over the past century however, we estimate that major explosive eruptions contribute <5% of the arc‐scale SO2emission budget. Ground‐based DOAS measurements of SO2 degassing at five of Papua New Guinea's volcanoes are compared with our OMI observations. The total OMI SO2 output is only ∼20% of the total extrapolated from DOAS, a discrepancy which we demonstrate is consistent with other volcanic arcs. Therefore, the true total regional SO2 output may be considerably higher than that detected by OMI. Uncertainties in the OMI SO2data include the effects of in‐plume chemical processing and dilution of SO2 prior to the satellite overpass, OMI's reduced sensitivity to low levels of SO2 in the planetary boundary layer and interference by meteorological clouds.
The SushiBar: An automated system for paleomagnetic investigations
Authors: Wack Michael R. , Gilder Stuart A.
Published: January 2012

We present a new, automated system based on a three‐axis superconducting magnetometer and a custom‐made coil designed to experiment on cylindrical specimens used in typical paleomagnetic investigations. The system, which resembles a sushi bar, facilitates stepwise alternating field demagnetization of up to 99 samples per loaded track. It also enables researchers to explore magnetic properties using an anhysteretic remanent magnetization (ARM) in any coercivity window up to peak alternating fields of 95 mT with direct current bias fields up to 0.17 mT. For example, partial ARM (pARM) spectra characterize magnetic grain size distributions in rocks, yet rarely are pARM spectra measured because the complete curve for one sample takes at least two hours to acquire manually. The SushiBar achieves 99 such curves in slightly less than 100 hours. Using the SushiBar, we measured the pARM sprectra, as well as the viscosity and anisotropy of ARM in three discrete switching field windows, of continental sediments from the Xishuigou section (western China). The average grain size remains constant along the 2200 m‐thick section, yet magnetic viscosity varies systematically from bottom to top of the section; samples with high magnetic viscosities also have higher proportions of non‐viscous material on average. Principal anisotropy axis directions from the lowest switching fields correlate well with principal axis directions from anisotropy of magnetic susceptibility. Principal axis directions defined at higher switching fields systematically deviate from those at lower switching fields, perhaps defining the fabric of the remanence‐carrying grains.
Excess hafnium‐176 in meteorites and the early Earth zircon record
Authors: Bizzarro Martin , Connelly James N. , Thrane Kristine , Borg Lars E.
Published: January 2012

The long‐lived176Lu‐to‐176Hf decay system is a powerful tool to understand ancient chemical fractionation events associated with planetary differentiation. Detrital Hadean zircons (>3.8 Gyr) from the Jack Hills metasedimentary belt of Western Australia record extremely enriched Hf‐isotope signals suggesting early extraction of a continental crust (>4.5 Gyr) but fail to identify a prevalent complementary depleted mantle reservoir, suggesting that crust formation processes in the early Earth were fundamentally distinct from today. However, this conclusion assumes that the Hf‐isotope composition of bulk chondrite meteorites can be used to estimate the composition of Earth prior to its differentiation into major silicate reservoirs, namely the bulk silicate Earth (BSE). We report a176Lu‐176Hf internal mineral isochron age of 4869 ± 34 Myr for the pristine SAH99555 angrite meteorite. This age is ∼300 Myr older than the age of the Solar System, confirming the existence of an energetic process yielding excess 176Hf in affected early formed Solar System objects through the production of the 176Lu isomer (t1/2 ∼3.9 hours). Thus, chondrite meteorites contain excess 176Hf and their present‐day composition cannot be used to infer the Lu‐Hf parameters of BSE. Using a revised BSE estimate based on the SAH99555 isochron, we show that Earth's oldest zircons preserve a record of coexisting enriched and depleted hafnium reservoirs as early as ∼4.3 Gyr in Earth's history, with little evidence for the existence of continental crust prior to ∼4.4 Gyr. This new view suggests continuous juvenile crustal growth and recycling throughout the Hadean and Archean eras, perhaps analogous to modern plate tectonics.
Stick, slip, and opening of wavy frictional faults: A numerical approach in two dimensions
Authors: Ritz Elizabeth , Pollard David D.
Published: January 2012

We use a two‐dimensional displacement discontinuity method (DDM) for quasi‐static boundary value problems to investigate sinusoidal faults of finite length in an otherwise homogeneous and isotropic elastic material. The DDM incorporates a complementarity algorithm to enforce appropriate contact boundary conditions along the model fault. The numerical solution for the model sinusoidal fault converges to the analytical solution for a straight fault of finite length as the ratio amplitude/wavelength goes to zero. It does not converge to the analytical solution for an infinite sinusoidal interface as the ratio distance/wavelength goes to zero. We provide stick, slip, and opening distributions along wavy faults with a range of uniform coefficients of friction, amplitude/wavelength ratios, and wave numbers. As the number of sinusoidal waves or the amplitude/wavelength is increased, mean slip decreases. Additionally, the fault geometry causes slip to deviate significantly from the elliptical distribution of a planar fault. We demonstrate that the displacement discontinuity of wavy faults cannot be prescribed a priori. This necessitates implementation of the complementarity algorithm and precludes an analytical solution. We employ the terms lee and stoss instead of releasing and restraining bends because a local minimum in slip may occur along lee sides, as well as stoss sides. In some cases, lee sides stick while stoss sides slip. Trends in the slip perturbation can be explained by the angular relationship between the local fault trace and the orientation of the remote principal stresses; however, the displacement discontinuity along a wavy model fault cannot be explained by this relationship alone.
Intralithospheric mantle structures recorded continental subduction
Authors: Zheng Tianyu , Zhu Rixiang , Zhao Liang , Ai Yinshuang
Published: January 2012

We investigated the intralithospheric mantle (ILM) structures beneath the North China Craton (NCC) by the seismic imaging with over 16,000 high‐quality receiver functions from 255 broadband stations. These images were created for six profiles spanning different tectonic units in the NCC. Initially, we inferred the crustal velocity model using an integrated receiver function imaging technique. Subsequently, we performed a series of synthetic tests of common conversion point (CCP) stacking images to distinguish between the multiple waves generated by the crustal structure and the velocity discontinuities in the ILM. The ILM structures were constructed by waveform inversion on the basis of these analyses. Our imaging results reveal (1) a homogenous lithospheric mantle in the western NCC, (2) intermittent and juxtaposed velocity interfaces in the ILM beneath the southern NCC, and (3) local high‐velocity and lower‐velocity volumes in the ILM beneath the eastern NCC. In addition, the lower crust beneath the southern NCC is thin, and the Moho dips northward, which present evidence of the Yangtze craton subduction beneath the NCC. The imaged high‐velocity volumes in the ILM beneath the southern NCC were interpreted as a subduction remnant in the uppermost mantle, which reveal a flat subduction channel resulting from the continent‐continent collision between the NCC and the Yangtze craton. The homogeneous ILM beneath a Paleoproterozoic amalgamation zone in the NCC implies that the remnants of the lithosphere that were subducted before 1.8 Ga might have sunk into the deeper mantle.
Anomalous intraseasonal events in the thermocline ridge region of Southern Tropical Indian Ocean and their regional impacts
Authors: Jayakumar A. , Gnanaseelan C.
Published: January 2012

The present study explores the mechanisms responsible for the strong intraseasonal cooling events in the Thermocline Ridge region of the southwestern Indian Ocean. Air sea interface and oceanic processes associated with Madden Julian Oscillation are studied using an Ocean General Circulation Model and satellite observations. Sensitivity experiments are designed to understand the ocean response to intraseasonal forcing with a special emphasis on 2002 cooling events, which recorded the strongest intraseasonal perturbations during the last well‐observed decade. This event is characterized by anomalous Walker circulation over the tropical Indian Ocean and persistent intraseasonal heat flux anomaly for a longer duration than is typical for similar events (but without any favorable preconditioning of ocean basic state at the interannual timescale). The model heat budget analysis during 1996 to 2007 revealed an in‐phase relationship between atmospheric fluxes associated with Madden Julian Oscillation and the subsurface oceanic processes during the intense cooling events of 2002. The strong convection, reduced shortwave radiation and increased evaporation have contributed to the upper ocean heat loss in addition to the slower propagation of active phase of convection, which supported the integration of longer duration of forcing. The sensitivity experiments revealed that dynamic response of ocean through entrainment at the intraseasonal timescale primarily controls the biological response during the event, with oceanic interannual variability playing a secondary role. This study further speculates the role of oceanic intraseasonal variability in the 2002 droughts over Indian subcontinent.
Comparison of optical and microphysical properties of pure Saharan mineral dust observed with AERONET Sun photometer, Raman lidar, and in situ instruments during SAMUM 2006
Authors: Müller D. , Lee K.‐H. , Gasteiger J. , Tesche M. , Weinzierl B. , Kandler K. , Müller T. , Toledano C. , Otto S. , Althausen D. , Ansmann A.
Published: January 2012

The Saharan Mineral Dust Experiment (SAMUM) 2006, Morocco, aimed at the characterization of optical, physical, and radiative properties of Saharan dust. AERONET Sun photometer, several lidars (Raman and high‐spectral‐resolution instruments), and airborne and ground‐based in situ instruments provided us with a comprehensive set of data on particle‐shape dependent and particle‐shape independent dust properties. We compare 4 measurement days in detail, and we carry out a statistical analysis for some of the inferred data products for the complete measurement period. Particle size distributions and complex refractive indices inferred from the Sun photometer observations and measured in situ aboard a research aircraft show systematic differences. We find differences in the wavelength‐dependence of single‐scattering albedo, compared to light‐scattering computations that use data from SOAP (spectral optical absorption photometer). AERONET data products of particle size distribution, complex refractive index, and axis ratios were used to compute particle extinction‐to‐backscatter (lidar) ratios and linear particle depolarization ratios. We find differences for these parameters to lidar measurements of lidar ratio and particle depolarization ratio. Differences particularly exist at 355 nm, which may be the result of differences of the wavelength‐dependent complex refractive index that is inferred by the methods employed in this field campaign. We discuss various error sources that may lead to the observed differences.
An annual cycle of size‐resolved aerosol hygroscopicity at a forested site in Colorado
Authors: Levin E. J. T. , Prenni A. J. , Petters M. D. , Kreidenweis S. M. , Sullivan R. C. , Atwood S. A. , Ortega J. , DeMott P. J. , Smith J. N.
Published: January 2012

The ability of particles composed wholly or partially of biogenic secondary organic compounds to serve as cloud condensation nuclei (CCN) is a key characteristic that helps to define their roles in linking biogeochemical and water cycles. In this paper, we describe size‐resolved (14–350 nm) CCN measurements from the Manitou Experimental Forest in Colorado, where particle compositions were expected to have a large biogenic component. These measurements were conducted for 1 year as part of the Bio‐hydro‐atmosphere Interactions of Energy, Aerosols, Carbon, H2O, Organics, and Nitrogen program and determined the aerosol hygroscopicity parameter, κ, at five water supersaturations between ∼0.14% and ∼0.97%. The average κ value over the entire study and all supersaturations was κavg = 0.16 ± 0.08. Kappa values decreased slightly with increasing supersaturation, suggesting a change in aerosol composition with dry diameter. Furthermore, some seasonal variability was observed with increased CCN concentrations and activated particle number fraction, but slightly decreased hygroscopicity, during the summer. Small particle events, which may indicate new particle formation, were observed throughout the study period, especially in the summer, leading to increases in CCN concentration, followed by a gradual increase in the aerosol mode size. The condensing material appeared to be predominantly composed of organic compounds and led to a small decrease in κ at the larger activation diameters during and immediately after those events.
Nanoparticle chemical composition and diurnal dependence at the CalNex Los Angeles ground site
Authors: Pennington M. Ross , Klems Joseph P. , Bzdek Bryan R. , Johnston Murray V.
Published: January 2012

The Nano Aerosol Mass Spectrometer (NAMS) was deployed to the California Nexus Los Angeles ground site in Pasadena, California during May–June 2010 to study nanoparticles in the 20–25 nm size range. NAMS gives a quantitative measure of the elemental composition of individual particles, and molecular apportionment of the elemental data allows the O/C mole ratio of carbonaceous matter in each particle to be determined. Abrupt increases in nanoparticle number concentration were observed in the afternoon on sunny days, and coincided with a shift in the wind direction from the southeast to the southwest. Nanoparticles analyzed during these time periods were found to contain enhanced levels of sulfur and silicon relative to particles analyzed earlier in the day, and the O/C ratios of carbonaceous matter changed from a distribution dominated by primary motor vehicle emissions (O/C ratio < 0.25) to one dominated by “fresh” secondary organic aerosol (O/C ratio between 0.25 and 0.65). The wind direction and chemical composition dependencies suggest that the afternoon increase in number concentration originated from motor vehicle emissions in the downtown Los Angeles area that were photochemically processed during transport to the measurement site. It is likely that photochemical processing led to both a change in the composition of preexisting particles and to the formation of new particles.
Investigating cloud absorption effects: Global absorption properties of black carbon, tar balls, and soil dust in clouds and aerosols
Authors: Jacobson Mark Z.
Published: January 2012

This study examines modeled properties of black carbon (BC), tar ball (TB), and soil dust (SD) absorption within clouds and aerosols to understand better Cloud Absorption Effects I and II, which are defined as the effects on cloud heating of absorbing inclusions in hydrometeor particles and of absorbing aerosol particles interstitially between hydrometeor particles at their actual relative humidity (RH), respectively. The globally and annually averaged modeled 550 nm aerosol mass absorption coefficient (AMAC) of externally mixed BC was 6.72 (6.3–7.3) m2/g, within the laboratory range (6.3–8.7 m2/g). The global AMAC of internally mixed (IM) BC was 16.2 (13.9–18.2) m2/g, less than the measured maximum at 100% RH (23 m2/g). The resulting AMAC amplification factor due to internal mixing was 2.41 (2–2.9), with highest values in high RH regions. The global 650 nm hydrometeor mass absorption coefficient (HMAC) due to BC inclusions was 17.7 (10.6–19) m2/g, ∼9.3% higher than that of the IM‐AMAC. The 650 nm HMACs of TBs and SD were half and 1/190th, respectively, that of BC. Modeled aerosol absorption optical depths were consistent with data. In column tests, BC inclusions in low and mid clouds (CAE I) gave column‐integrated BC heating rates ∼200% and 235%, respectively, those of interstitial BC at the actual cloud RH (CAE II), which itself gave heating rates ∼120% and ∼130%, respectively, those of interstitial BC at the clear‐sky RH. Globally, cloud optical depth increased then decreased with increasing aerosol optical depth, consistent with boomerang curves from satellite studies. Thus, CAEs, which are largely ignored, heat clouds significantly.
The oblique impact Hale and its consequences on Mars
Authors: Schultz Peter H. , Wrobel Kelly E.
Published: January 2012

Highly oblique impacts represent a rare and special class of impact events manifested as elliptical craters preserved on present‐day planetary surfaces. Crater excavation in highly oblique impacts differs from that of standard vertical impacts due to early time asymmetries imparted by the downrange‐directed coupling of energy between the projectile and target. Such asymmetries are preserved as scouring and mobilized surface materials produced by high‐velocity, low‐angle ejecta and blast winds along the initial impact trajectory axis downrange. Subsequent deposition of resulting melt‐rich products occurs in the form of concentrated strewnfields located downrange from the impact. The distinct nature of these distal strewnfields is separate from later time, more proximal ejecta accumulations and generally allows connecting these specific deposits with their parent crater. The present study involves a three‐dimensional computational impact simulation (modeled using the CTH shock physics hydrocode) of an event similar to the impact that produced the elliptical Hale impact crater on Mars (125 km × 150 km diameter crater located at 36°S, 36°W). Results generally capture the predicted patterns indicative of highly oblique impacts. Evidence is presented for correlated distal strewnfields located downrange from Hale that coincide with prominent low‐albedo surface deposits and wind streaks on the present‐day Martian surface, thereby providing implications for possible identification for other dark glassy strewnfields as well as impact‐generated winds on Mars.
The formation of Valles Marineris: 1. Tectonic architecture and the relative roles of extension and subsidence
Authors: Andrews‐Hanna Jeffrey C.
Published: January 2012

The formation of the Valles Marineris troughs on Mars is widely held to involve some combination of horizontal extension and vertical subsidence or collapse, but the specific tectonic mechanism is poorly understood. This study uses boundary element models of Valles Marineris formation to evaluate a range of fault dip angles for two end‐member models of trough formation: simple extensional tectonism, and extension together with vertical accommodation at the base of the lithosphere representing either viscous lower crustal flow or some other form of deep‐seated collapse. The models are constrained by the lack of footwall uplift on the plateau surface outside the troughs, and the lack of significant tectonic failure of the plateau in response to the stress changes induced by Valles Marineris formation. The results demonstrate that trough formation by extensional tectonism alone generates large surface uplifts in the surrounding plateau and enormous stresses in the lithosphere, in conflict with the observations. The only mechanism that is compatible with both the observed topography and the limitations imposed by the finite strength of the lithosphere is trough formation through displacement along steeply dipping to subvertical border faults, together with vertical accommodation at the base of the subsiding fault block. Fault dips are constrained to be greater than or equal to 85°, leading to a ratio of vertical subsidence to horizontal extension exceeding 5.7 and a maximum extension of less than 4.6 km. These results confirm earlier studies suggesting that trough formation involved a substantial component of vertical subsidence or collapse, with only modest amounts of total extension.
Periodic bedrock ridges on Mars
Authors: Montgomery David R. , Bandfield Joshua L. , Becker Scott K.
Published: January 2012

Evidence for sediment transport and erosion by wind is widespread over the surface of Mars today and was likely a major geomorphic process for much of its geological past. Although Martian surface features resembling aeolian dunes and ripples have been recognized since the Mariner and Viking missions, such features have been interpreted previously as active, indurated, or exhumed sedimentary forms. Here we report evidence based on High Resolution Imaging Science Experiment images that show some megaripple forms are eroded into cohesive substrate rather than being composed of loose granular material or fossilized dunes. Exposure of stratigraphic continuity within layered, cohesive material extending crest to trough through features with mean wavelengths of 18 to 51 m demonstrates the primarily erosional formation of what we term periodic bedrock ridges (PBRs). Hence some surfaces on Mars previously considered to be covered by wind‐deposited material are actually wind‐carved exposures that offer windows into Martian history. PBRs lack the distinctive streamlining associated with wind‐parallel yardangs and comparison of PBR orientation to yardangs, megayardangs, and active sedimentary dunes in the same vicinity confirm that these PBRs formed transverse to prevailing winds. Observed wavelengths of PBRs are comparable to those predicted by a simple model for erosional wavelengths of periodic transverse bed forms owing to the spacing of flow separations within the flow. Recognition of these transverse aeolian erosional forms brings up the question of how widespread Martian PBRs are and how many have been misinterpreted as active or indurated (fossilized) sedimentary dunes.
Equilibrium form of horizontally retreating, soil‐mantled hillslopes: Model development and application to a groundwater sapping landscape
Authors: Perron J. Taylor , Hamon Jennifer L.
Published: January 2012

We present analytical solutions for the steady state topographic profile of a soil‐mantled hillslope retreating into a level plain in response to a horizontally migrating base level. This model applies to several scenarios that commonly arise in landscapes, including widening valleys, eroding channel banks, and retreating scarps. For a sediment transport law in which sediment flux is linearly proportional to the topographic slope, the steady state profile is exponential, with an e‐folding length, L, proportional to the ratio of the sediment transport coefficient to the base level migration speed. For the case in which sediment flux increases nonlinearly with slope, the solution has a similar form that converges to the linear case as L increases. We use a numerical model to explore the effects of different base level geometries and find that the one‐dimensional analytical solution is a close approximation for the hillslope profile above an advancing channel tip. We then compare the analytical model with hillslope profiles above the tips of a groundwater sapping channel network in the Florida Panhandle. The model agrees closely with hillslope profiles measured from airborne laser altimetry, and we use a predicted log linear relationship between topographic slope and horizontal distance to estimate L for the measured profiles. Mapping 1/L over channel tips throughout the landscape reveals that adjacent channel networks may be growing at different rates and that south facing slopes experience more efficient hillslope transport.
Carbon isotopic evidence for the associations of decreasing atmospheric CO2level with the Frasnian‐Famennian mass extinction
Authors: Xu Bing , Gu Zhaoyan , Wang Chengyuan , Hao Qingzhen , Han Jingtai , Liu Qiang , Wang Luo , Lu Yanwu
Published: January 2012

A perturbation of the global carbon cycle has often been used for interpreting the Frasnian‐Famennian (F‐F) mass extinction. However, the changes of atmospheric CO2 level (pCO2) during this interval are much debatable. To illustrate the carbon cycle during F‐F transition, paired inorganic (δ13Ccarb) and organic (δ13Corg) carbon isotope analyses were carried out on two late Devonian carbonate sequences (Dongcun and Yangdi) from south China. The larger amplitude shift of δ13Corg compared to δ13Ccarb and its resultant Δ13C (Δ13C = δ13Ccarb − δ13Corg) decrease indicate decreased atmospheric CO2level around the F‐F boundary. The onset ofpCO2 level decrease predates that of marine regressions, which coincide with the beginning of conodont extinctions, suggesting that temperature decrease induced by decreased greenhouse effect of atmospheric CO2might have contributed to the F‐F mass extinction.
Improvement of equatorial density distribution of the global core plasma model using GPS‐derived TEC
Authors: Goto Y. , Kasahara Y. , Ide T.
Published: January 2012

The global core plasma model (GCPM) is a realistic electron density model of the inner magnetosphere. By using long‐term total electron content (TEC) data obtained from several GPS tracking stations along the equator and a low Earth orbit satellite, the accuracy of the GCPM equatorial density is examined. According to the statistical analysis of the GPS TEC, we found a remarkable feature in bias errors in the GCPM‐derived TEC. Most of the errors are found to distribute in the topside ionosphere due to the simple representation of the density there.
Resolution of the sprite polarity paradox: The role of halos
Authors: Williams E. , Kuo C.‐L. , Bór J. , Sátori G. , Newsome R. , Adachi T. , Boldi R. , Chen A. , Downes E. , Hsu R. R. , Lyons W. , Saba M. M. F. , Taylor M. , Su H. T.
Published: January 2012

This study revisits the sprite polarity paradox, first manifest by observations that exceptional cloud‐to‐ground flashes with negative polarity generally did not produce detectable sprites. The paradox is here resolved by the Transient Luminous Event (TLE) known as the halo, which on account of its inferior brightness (0.3 MR versus 1.5 MR) and substantially shorter duration (1 ms versus 10–100 ms) in comparison with the sprite, is not readily detectable in ground‐based video cameras with standard field duration (16.7–20 ms). Observations with improved temporal resolution (ISUAL (Imager of Sprites and Upper Atmospheric Lightnings) from space and PIPER (Photometric Imager of Precipitated Electron Radiation) observations from the ground) provide evidence that flashes with negative polarity dominate the global halo population, and that the halo numbers are more than sufficient to account for the previously missing TLEs. The evidence for lightning polarity‐dependent TLEs (sprites, positive and halos, negative) is attributable to the well established but incompletely understood contrast in the behavior of negative and positive lightning flashes to ground.
Fabrication and characterization of ambipolar devices on an undoped AlGaAs/GaAs heterostructure
Authors: Chen J. C. H. , Wang D. Q. , Klochan O. , Micolich A. P. , Das Gupta K. , Sfigakis F. , Ritchie D. A. , Reuter D. , Wieck A. D. , Hamilton A. R.
Published: January 2012

We have fabricated AlGaAs/GaAs heterostructure devices in which the conduction channel can be populated with either electrons or holes simply by changing the polarity of a gate bias. The heterostructures are entirely undoped, and carriers are, instead, induced electrostatically. We use these devices to perform a direct comparison of the scattering mechanisms of two-dimensional electrons (μpeak = 4 × 106 cm2/Vs) and holes (μpeak = 0.8 × 106 cm2/Vs) in the same conduction channel with nominally identical disorder potentials. We find significant discrepancies between electron and hole scattering, with the hole mobility being considerably lower than expected from simple theory.
Spectroscopic reflectometry of mirror surfaces during plasma exposure
Authors: Wisse M. , Eren B. , Marot L. , Steiner R. , Meyer E.
Published: January 2012

An in situ spectroscopic reflectometry system has been built to investigate the evolution of the specular reflectivity spectrum of ITER first mirror samples during plasma exposure. Results are presented for three different types of molybdenum mirror samples that were exposed to deuterium plasma, including single crystalline, nanocrystalline, and polycrystalline molybdenum. The results show good agreement with ex situ measurements of the reflectivity spectrum before and after exposure and extend the results obtained in previous experiments.
Influence of charge compensation mechanisms on the sheet electron density at conducting LaAlO3/SrTiO3-interfaces
Authors: Gunkel F. , Brinks P. , Hoffmann-Eifert S. , Dittmann R. , Huijben M. , Kleibeuker J. E. , Koster G. , Rijnders G. , Waser R.
Published: January 2012

The equilibrium conductance of LaAlO3/SrTiO3 (LAO/STO)-heterointerfaces was investigated at high temperatures (950 K-1100 K) as a function of ambient oxygen partial pressure (pO2). Metallic LAO/STO-interfaces were obtained for LAO grown on STO single crystals as well as on STO-buffered (La,Sr)(Al,Ta)O3 substrates. For both structures, the high temperature sheet carrier density nS of the LAO/STO-interface saturates at a value of about 1 × 1014 cm−2 for reducing conditions, which indicates the presence of interfacial donor states. A significant decrease of nS is observed at high oxygen partial pressures. According to the defect chemistry model of donor-doped STO, this behavior for oxidizing conditions can be attributed to the formation of Sr-vacancies as charge compensating defects.