bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface Localization of Buried III–V Semiconductor Nanostructures
Authors: Alonso-González P , González L , Fuster D , Martín-Sánchez J , González Yolanda
Published: May 2009

In this work, we study the top surface localization of InAs quantum dots once capped by a GaAs layer grown by molecular beam epitaxy. At the used growth conditions, the underneath nanostructures are revealed at the top surface as mounding features that match their density with independence of the cap layer thickness explored (from 25 to 100 nm). The correspondence between these mounds and the buried nanostructures is confirmed by posterior selective strain-driven formation of new nanostructures on top of them, when the distance between the buried and the superficial nanostructures is short enough (d = 25 nm).
Detection of Autoantibodies to Annexin A11 in Different Types of Human Cancer
Authors: Song Jin , Sun Xiaer , Sokoll Lori J. , Maki Masatoshi , Tian Yuan , Chan Daniel W. , Zhang Zhen
Published: May 2009

Introduction

Annexin A11 was previously identified as an autoantigen in 4.1–10.1% of patients with various systemic autoimmune diseases. In this study, an enzyme-linked immunosorbent assay (ELISA) was developed to investigate the occurrence and features of anti-annexin A11 autoantibodies in sera from patients with different types of cancer.

Methods

The recombinant protein of GST fused to the N-terminal domain (1–175 residues) of human annexin A11 was expressed and used as antigen in ELISA. A total of 246 serum specimens were analyzed, which includes sera from healthy women (77), patients with ovarian cancer (72), breast cancer (18), colon cancer (19), pancreatic cancer (20), prostate cancer (20), and diabetes (20).

Results

The overall titer of anti-annexin A11 autoantibodies in ovarian cancer patients (or primary tumors only) was found much higher than that in healthy controls (P < 0.05). At the cut-off value designating positive reaction, anti-annexin A11 autoantibodies were detected in 12.5% (5/40) of primary ovarian cancer patients with a significant difference from 2.6% (2/77) of the healthy controls (P < 0.05), but only in 6.25% (2/32) of recurrent tumors. ROC curve demonstrated the potential diagnostic value of anti-annexin A11 autoantibodies in primary ovarian cancer patients with an AUC of 0.62 (0.52–0.73). Anti-annexin A11 autoantibodies were also detected in 5.26% (1/19) of colon cancer and 10% (2/20) of diabetes patients but without significant difference from the healthy controls.

Conclusion

A convenient assay to detect anti-annexin A11 autoantibodies in patients was developed, and the experimental data are promising but need to be expanded to address their biological/clinical relevance.
Gender and grade‐level comparisons in the structure of problem behaviors among adolescents
Authors: Chun Heejung , Mobley Michael
Published: May 2009

Based on Jessor's theory (1987) the comparability of a second‐order problem behavior model (SPBM) was investigated across gender and grade‐level among adolescents. In addition, gender and grade‐level differences in problem behavior engagement were addressed examining latent mean differences. Using a sample of 6504 adolescents drawn from the National Longitudinal Study of Adolescent Health, a series of invariance tests evidenced partial invariance. The non‐invariance of SPBM resulted from aggression across gender and grade‐level. Latent mean difference test results showed greater differences in academic failure, aggression, substance use, and risky sexual activity among males compared to females. Results also showed greater engagement in academic failure, substance use, and risky sexual activity among upper vs. lower grade students. Overall, analyses revealed that both gender and grade‐level differences could be explained by the common cause problem behavior syndrome (PBS), offering further support for Jessor's theory.
Brief report: Predictors of heavy Internet use and associations with health‐promoting and health risk behaviors among Hong Kong university students
Authors: Kim Jean H. , Lau C.H. , Cheuk Ka‐Kin , Kan Pauline , Hui Heidi L.C. , Griffiths Sian M.
Published: May 2009

To examine the correlates of heavy Internet use and determine the associations of heavy Internet use with various health risk behaviors and health‐promoting behaviors among Chinese adolescents, an anonymous, self‐administered health behavior questionnaire was completed by 2427 matriculants into a Hong Kong university (mean age = 18.9 y) and returned at compulsory health examination. Of students, 14.8% reported heavy Internet use (>4 h/day) and such use was associated with lower likelihood of engaging in health‐promoting activities such as exercising and seeking medical care. At the same time, heavy Internet use was correlated with multiple risk behaviors such as skipping meals and sleeping late as well as poorer health outcomes such as higher likelihood of being overweight or having hypersomnia. Given the double burden of poorer health outcomes and fewer health‐promoting behaviors, heavy Internet users represent a particularly challenging group for adolescent health promotion.
Quantitative determination and comparison of the glycosaminoglycan Δ‐disaccharide composition in 22 different human cell lines
Authors: Ambrosius Michael , Kleesiek Knut , Götting Christian
Published: May 2009

Changes in proteoglycan and glycosaminoglycan (GAG) content and distribution may play an important role in the development of many diseases, atherosclerosis, cancer and diabetes. Human cell lines act as models for the underlying pathomechanisms. Despite the importance of proteoglycans for cell functioning, information on the GAG composition of most human cell lines is limited. Comparative analysis of the GAG Δdisaccharide amount in 22 human cell lines yielded a mean value of 94 ± 58 pmol/106 cells (mean ± SEM). Total GAG amount and heparan sulfate/heparin Δdisaccharide composition, but not chondroitin sulfate/dermatan sulfate Δdisaccharide composition, differed significantly between the investigated adherent and suspension cell lines. We provide a novel overview of GAG Δdisaccharide composition in 22 different human cell lines.
Proteomics and transcriptome approaches to investigate the mechanism of human sex determination
Authors: Sato Youichi , Shinka Toshikatsu , Chen Gang , Yan Hong‐Tao , Sakamoto Kozue , Ewis Ashraf A. , Aburatani Hiroyuki , Nakahori Yutaka
Published: May 2009

TheSRYgene (sex‐determining region on the Y chromosome) was isolated in 1990 and is known as the testis‐determining factor on the Y chromosome. The SRY has been considered as a transcription factor since it contains an HMG box, which functions as a DNA‐binding domain. However, a direct target for SRY remains to be identified. We have investigated the function of SRY through proteomics and transcriptome approaches, and by using two stable SRY‐overexpressing cell lines (SRY1 and SRY2) in NT2/D1 cells derived from human testicular embryonal cell carcinoma. The results of 2‐dimensional gel electrophoresis show that SRY overexpression causes a considerable downregulation of many chaperone proteins. SRY also upregulates laminin, which is important for Sertoli cell differentiation. Additionally, transcriptome analysis shows that SRY overexpression upregulates many zinc finger proteins and downregulates cellular growth factors with S or G2/M arrest of the cell cycle and inhibition of cellular proliferation.
BMP‐2 treatment of C3H10T1/2 mesenchymal cells blocks MMP‐9 activity during chondrocyte commitment
Authors: Choi Young‐Ae , Kang Shin‐Sung , Jin Eun‐Jung
Published: May 2009

Members of both the Wnt and bone morphogenetic protein (BMP) families of signaling molecules have been implicated in the regulation of cartilage development. We explored the underlying mechanism of BMP‐2‐induced chondrocyte commitment of C3H10T1/2 cells. Treating cells with exogenous BMP‐2 was tied to chondrocyte commitment by inhibiting matrix metalloproteinase‐9 activity (MMP‐9: 92 kDa type IV collagenase/gelatinase B). Glycogen synthase kinase (GSK)‐3β inhibition by its specific inhibitor blocked BMP‐2‐induced chondrocyte commitment by stimulating MMP‐9 activity. These findings indicate that the downregulation of MMP‐9 by BMP‐2 is associated with chondrocyte commitment, and that the GSK‐3β signaling pathway is involved in this process.
Effects of variation in the human α2A‐ and α2C‐adrenoceptor genes on cognitive tasks and pain perception
Authors: Kohli Utkarsh , Muszkat Mordechai , Sofowora Gbenga G. , Harris Paul A. , Friedman Eitan A. , Dupont William D. , Scheinin Mika , Wood Alastair J.J. , Stein C. Michael , Kurnik Daniel
Published: May 2009

Background: The mechanisms underlying interindividual variability in pain perception and cognitive responses are undefined but highly heritable. α2C‐ and α2A‐adrenergic receptors regulate noradrenergic activity and are important mediators of pain perception and analgesia. We hypothesized that common genetic variants in these genes, particularly the ADRA2C 322–325 deletion variant, affect pain perception or cognitive responses.

Methods: We studied 73 healthy subjects (37 Caucasians and 36 African–Americans) aged 25.4 ± 4.6 years. Pain response to a cold pressor test was measured using a 10 cm visual analog scale and again on the next day, after three infusions of the selective α2‐agonist dexmedetomidine. Standardized cognitive tests were administered at baseline and after each infusion. The contribution of ADRA2C deletion genotype, dexmedetomidine concentration, and other covariates to pain perception and cognitive responses was determined using multiple linear regression models. Secondary analysis examined the effects of ADRA2A and other ADRA2C variants on pain perception.

Results: ADRA2C Del homozygotes had higher pain scores in response to cold at baseline (6.3 ± 1.8 cm) and after dexmedetomidine (5.6 ± 2.2 cm) than insertion allele carriers (4.6 ± 2.1 cm [baseline] and 3.8 ± 1.9 cm [after dexmedetomidine]; adjusted P‐values = 0.019 and 0.004, respectively). Cognitive responses were unrelated to ADRA2C Ins/Del genotype. None of the other ADRA2A and ADRA2C variants was significantly related to cold pain sensitivity before dexmedetomidine; after dexmedetomidine, ADRA2A rs1800038 was marginally associated (P = 0.03).

Conclusion: The common ADRA2C del322–325 variant affected pain perception before and after dexmedetomidine but did not affect other cognitive responses, suggesting that it contributes to interindividual variability in pain perception.
Activity of the circadian transcription factor White Collar Complex is modulated by phosphorylation of SP‐motifs
Authors: Sancar Gencer , Sancar Cigdem , Brunner Michael , Schafmeier Tobias
Published: May 2009

MINT‐7033885: WC‐2 (uniprotkb:P78714) physically interacts (MI:0218) with FRQ (uniprotkb:P19970) and WC‐1 (uniprotkb:Q01371) by cross‐linking studies (MI:0030)
The intrinsic fluorescence of apo‐obelin and apo‐aequorin and use of its quenching to characterize coelenterazine binding
Authors: Eremeeva Elena V. , Markova Svetlana V. , Westphal Adrie H. , Visser Antonie J.W.G. , van Berkel Willem J.H. , Vysotski Eugene S.
Published: May 2009

The intrinsic fluorescence of two apo‐photoproteins has been characterized and its concentration‐dependent quenching by coelenterazine has been for the first time applied to determine the apparent dissociation constants for coelenterazine binding with apo‐aequorin (1.2 ± 0.12 μM) and apo‐obelin (0.2 ± 0.04 μM). Stopped‐flow measurements of fluorescence quenching showed that coelenterazine binding is a millisecond‐scale process, in contrast to the formation of an active photoprotein complex taking several hours. This finding evidently shows that the rate‐limiting step of active photoprotein formation is the conversion of coelenterazine into its 2‐hydroperoxy derivative.
Prevalence rates for dementia and Alzheimer's disease in African Americans: 1992 versus 2001
Authors: Hall Kathleen S. , Gao Sujuan , Baiyewu Olusegun , Lane Kathleen A. , Gureje Oye , Shen Jianzhao , Ogunniyi Adesola , Murrell Jill R. , Unverzagt Frederick W. , Dickens Jeanne , Smith-Gamble Valerie , Hendrie Hugh C.
Published: May 2009

Background

This study compares age‐specific and overall prevalence rates for dementia and Alzheimer's disease (AD) in two nonoverlapping, population‐based cohorts of elderly African Americans in Indianapolis in 2001 and 1992.

Methods

We used a two‐stage design. The first stage involves the Community Screening Interview for Dementia (CSI‐D). The CSI‐D scores are grouped into good, intermediate, and poor performance before selection for clinical assessment. Diagnoses were performed using standard criteria in a consensus diagnosis conference; clinicians were blind to performance groups. In 1992, interviewers visited randomly sampled addresses to enroll self‐identified African Americans aged ≥65 years. Of 2582 eligible, 2212 enrolled (9.6% refused, and 4.7% were too sick). In 2001, Medicare rolls were used for African Americans aged >70 years. Of 4260 eligible, 1892 (44%) enrolled, 1999 (47%) refused, and the remainder did not participate for other reasons.

Results

The overall age‐adjusted prevalence rate for dementia at age ≥70 years in 2001 was 7.45% (95 confidence interval [CI], 4.27–10.64), and in the 1992 cohort, this prevalence rate was 6.75% (95% CI, 5.77–7.74). The overall age‐adjusted prevalence rate at age ≥70 years for AD in the 2001 cohort was 6.77% (95% CI, 3.65–9.90), and for the 1992 cohort, it was 5.47% (95% CI, 4.51–6.42). Rates for dementia and AD were not significantly different in the two cohorts (dementia, P = .3534; AD, P = .2649).

Conclusions

We found no differences in the prevalence rates of dementia and AD between 1992 and 2001, despite significant differences in medical history and medical treatment within these population‐based cohorts of African American elderly.
Helping Hand or Grabbing Hand? State Bureaucracy and Privatization Effectiveness
Authors: BROWN J. DAVID , EARLE JOHN S. , GEHLBACH SCOTT
Published: May 2009

Why have economic reforms aimed at reducing the role of the state been successful in some cases but not others? Are reform failures the consequence of leviathan states that hinder private economic activity, or of weak states unable to implement policies effectively and provide a supportive institutional environment? We explore these questions in a study of privatization in postcommunist Russia. Taking advantage of large regional variation in the size of public administrations, and employing a multilevel research design that controls for preprivatization selection in the estimation of regional privatization effects, we examine the relationship between state bureaucracy and the impact of privatization on firm productivity. We find that privatization is more effective in regions with relatively large bureaucracies. Our analysis suggests that this effect is driven by the impact of bureaucracy on the postprivatization business environment, with better institutional support and less corruption when bureaucracies are large.
Helminth parasites of Leptodactylus podicipinus (Anura: Leptodactylidae) from south-eastern Pantanal, State of Mato Grosso do Sul, Brazil
Authors: Campião K.M. , da Silva R.J. , Ferreira V.L.
Published: May 2009

Forty-three specimens of Leptodactylus podicipinus (Anura: Leptodactylidae) were collected in the south-eastern Pantanal, municipality of Corumbá, State of Mato Grosso do Sul, Brazil in February and July 2007, and examined for endoparasites. Forty (93%) specimens were infected with at least one helminth species. The predominant parasites were nematodes (Aplectana sp., Cosmocerca podicipinus, Oswaldocruzia lopesi, Physalopteroides venancioi, Rhabdias sp.), but the trematode Catadiscus propinquus also showed high prevalence. The trematodes Infidum infidum and Travtrema stenocotyle were also found, but in only one specimen. Adult frogs showed higher parasite diversity than subadults. Leptodactylus podicipinus was preferentially infected by direct life-cycle parasites and was reported as a new host record for seven helminth species.
The nature of phonetics
Authors: Laver John
Published: May 2009

In ‘The Future of Phonetics’, Klaus Kohler sets out his personal view of modern phonetics as an integrated subject. He sets his vision of the future of phonetics, seen broadly as the study of the spoken medium of language, in a historical perspective. He is concerned to argue that modern phonetics is not the juxtaposition of subjects dealing with the spoken medium, but should be considered to be an autonomous subject. His argument is both academic and political, in that he suggests that independent departments of phonetics, with their own budgets, would thereby be protected from the loss of staff, funds, research and teaching activities that he describes as happening in several cases after amalgamation with linguistics.
Comparative effects of mites and lice on the reproductive success of rock doves (Columba livia)
Authors: Clayton D. H. , Tompkins D. M.
Published: May 2009

We report experimental data comparing the effects of Mesostigmatid mites and Ischnoceran lice on the reproductive performance of a single group of captive rock doves (Columba livia). Several components of host reproductive success were compared for the two groups, including number of eggs laid, hatching success, nestling growth rates, fledging success, post-fledging body mass and survival. Adult body mass and survival were also compared. There was a dramatic difference in the effects of the mites and lice. The former drove host reproductive success to zero, mainly by agitating adults and causing them to incubate eggs less faithfully. Nestling growth rates and post-fledging survival were also significantly reduced by mites. Lice showed no effect on reproductive success whatsoever, even though the feather damage they cause is known to have energetic consequences (Booth, Clayton & Block, 1993). Neither parasite had a significant effect on adult birds. Although Ischnocera are found on most species of birds, our results for lice constitute the first experimental test of the impact of Ischnocera on avian reproductive success (preliminary report by Clayton & Tompkins, 1994). We discuss reasons for the different effects of mites and lice, including the relationship of horizontal (mites) and vertical (lice) transmission to the evolution of virulence.
Adaptivity with moving grids
Authors: Budd Chris J. , Huang Weizhang , Russell Robert D.
Published: May 2009

In this article we surveyr-adaptive (or moving grid) methods for solving time-dependent partial differential equations (PDEs). Although these methods have received much less attention than theirh- andp-adaptive counterparts, particularly within the finite element community, we review the substantial progress that has been made in developing more robust and reliable algorithms and in understanding the basic principles behind these methods, and we give some numerical examples illustrative of the wide classes of problems for which these methods are suitable alternatives to the traditional ones.

More specifically, we first examine the basic geometric properties of moving meshes in both one and higher spatial dimensions, and discuss the discretization process for PDEs on such moving meshes (both structured and unstructured). In particular, we consider the issues of mesh regularity, equidistribution, alignment, and associated variational methods. An overview is given of the general interpolation error analysis for a function or a truncation error on such an adaptive mesh. Guided by these principles, we show how to design effective moving mesh strategies. We then examine in more detail how these strategies can be implemented in practice. The first class of methods which we consider are based upon controlling mesh density and hence are called position-based methods. These make use of a so-called moving mesh PDE (MMPDE) approach and variational methods, as well as optimal transport methods. This is followed by an analysis of methods which have a more Lagrange-like interpretation, and due to this focus are called velocity-based methods. These include the moving finite element method (MFE), the geometric conservation law (GCL) methods, and the deformation map method. Finally, we present a number of specific types of examples for which the use of a moving mesh method is particularly effective in applications. These include scale-invariant problems, blow-up problems, problems with moving fronts and problems in meteorology. We conclude that, whilstr-adaptive methods are still in their relatively early stages of development, with many outstanding questions remaining, they have enormous potential and indeed can produce an optimal form of adaptivity for many problems.
Blow-up or no blow-up? A unified computational and analytic approach to 3D incompressible Euler and Navier–Stokes equations
Authors: Hou Thomas Y.
Published: May 2009

Whether the 3D incompressible Euler and Navier–Stokes equations can develop a finite-time singularity from smooth initial data with finite energy has been one of the most long-standing open questions. We review some recent theoretical and computational studies which show that there is a subtle dynamic depletion of nonlinear vortex stretching due to local geometric regularity of vortex filaments. We also investigate the dynamic stability of the 3D Navier–Stokes equations and the stabilizing effect of convection. A unique feature of our approach is the interplay between computation and analysis. Guided by our local non-blow-up theory, we have performed large-scale computations of the 3D Euler equations using a novel pseudo-spectral method on some of the most promising blow-up candidates. Our results show that there is tremendous dynamic depletion of vortex stretching. Moreover, we observe that the support of maximum vorticity becomes severely flattened as the maximum vorticity increases and the direction of the vortex filaments near the support of maximum vorticity is very regular. Our numerical observations in turn provide valuable insight, which leads to further theoretical breakthrough. Finally, we present a new class of solutions for the 3D Euler and Navier–Stokes equations, which exhibit very interesting dynamic growth properties. By exploiting the special nonlinear structure of the equations, we prove nonlinear stability and the global regularity of this class of solutions.
Distributional determinants of household air pollution in China
Authors: PAPINEAU MAYA , AUNAN KRISTIN , BERNTSEN TERJE
Published: May 2009

Solid fuel burning in households is a leading health risk for people in developing countries. Several studies of indoor air pollution from solid fuels have analyzed the problem at the village and household level, but to design effective policies it is important to understand the large-scale socioeconomic drivers of household air pollution (HAP). Using county-level data covering all of China, we examine relationships between socioeconomic variables and ambient concentrations of PM and SO2 resulting from household energy use. Applying both non-parametric and parametric techniques, we find that income and education are robust determinants of HAP; structural characteristics affect the HAP turning points; and the poorest counties bear a disproportionate amount of total pollution, especially urban counties and counties located in the coastal provinces.
Kinder- und jugendpsychiatrische Forschung, Förderung des wissenschaftlichen Nachwuchses und Veröffentlichungspraxis
Authors: Lehmkuhl Gerd , Petermann Franz , Warnke Andreas
Published: May 2009

Um die deutschsprachige kinder- und jugendpsychiatrische Forschung international besser sichtbar zu machen, wird auf die Notwendigkeit einer veränderten Publikationsstrategie in deutschsprachigen Zeitschriften hingewiesen. Hierbei geht es vor allem um eine Erhöhung des Impact-Faktors, kürzere Zeiträume für Begutachtung und Publikationszeiträume, eine bessere Aktualität der zitierten Literatur, eine Betonung der Interdisziplinarität sowie eine engere Kooperation mit Herausgebergremien in Nachbardisziplinen. Diese vermehrten Anstrengungen sind notwendig, damit deutschsprachige Publikationen besser wahrgenommen werden können und der internationale Anschluss nicht verloren geht.
Schwere katatone Schizophrenie einer 17-jährigen Jugendlichen
Authors: Sixt Barbara , van Aaken Claas , Hennighausen Klaus , Fleischhaker Christian , Schulz Eberhard
Published: May 2009

Fragestellung: Katatone Symptome im Kindes- und Jugendalter sind wenig erforscht. Evaluierte Therapieempfehlungen gibt es kaum. Krankheitsverlauf und Behandlung einer schweren katatonen Schizophrenie sind Gegenstand der Kasuistik. Methodik: Kasuistisch wird eine 17-jährige Jugendliche mit einer schweren, lebensbedrohlichen katatonen Schizophrenie vorgestellt. Ergebnis: die Behandlung mit Clozapin erbrachte nach bis dahin erfolgloser Vorbehandlung eine entscheidende Verbesserung der Symptomatik Schlussfolgerungen: Weitere Untersuchungen und Fallberichte über die Behandlung und den Verlauf des seltenen Krankheitsbildes der schweren katatonen Schizophrenie im Kindes- und Jugendalters wären wünschenswert.
Nagt Joghurt an den Herzklappen?
Authors: Noti  , Zimmerli  , Goerre  , Carrel  , Suter
Published: May 2009

Wir beschreiben einen 22-jährigen Mann mit vorbekannter Herzklappenpathologie, der sechs Wochen nach einem zahnärztlichen Eingriff trotz adäquater Prophylaxe an einer akuten Laktobazillus-Endokarditis erkrankte. Wir erläutern die Limitationen der alten Empfehlungen zur Endokarditisprophylaxe und beschreiben die neuen Richtlinien. Im weiteren diskutieren wir die Behandlung der Laktobazillus-Endokarditis und legen eine mögliche gesundheitliche Gefährdung immunkompromittierter / immunsupprimierter Patienten durch den steigenden Einsatz der Laktobazillus-Spezies in Milchprodukten dar.
HF Doppler radar observations of low‐latitude spread F
Authors: Reddi C. R. , Sarma M. S. S. R. K. N. , Niranjan K.
Published: May 2009

HF (5.5 MHz) Doppler radar observations of nonspread F and spread F echoes over Visakhapatnam (17.7°N, 83.3°E; dip 20°) are presented. The echoes appearing suddenly and nearly simultaneously in 16 successive range bins at 7.5 km intervals in association with spread F have been investigated. Two to five episodes of spread F activity were found to appear at intervals of 1–2 hours during individual nights. At the time of onset of spread F conditions, the Doppler velocity for each range bin changed rapidly from a negative maximum to a positive maximum followed by a gradual decrease to a steady ±10–15 m/s or to a large negative velocity and then again to a large positive. At the time of small constant velocity or velocity change from negative to positive, the spread F echoes were weak or even below the detection level of the radar. This disappearance in the higher ranges causes the decrease in range extent of spread F echoes. The positive and negative maximum velocities of spread F were in the range of +70 to −60 m/s. The maximum upward and downward velocity is not the same in all events of spread F activity. The width of the Doppler velocity spectrum for spread F echoes was found to vary with velocity. For zero velocity the width was a minimum of 50 m/s in contrast to 25 m/s for nonspread F events. These features were consistently observed for all spread F incidences. The observed results are compared with already reported HF/VHF observations and are discussed in the light of equatorial plasma dynamics during the growth phase of Rayleigh Taylor instability leading the incidence of spread F.
Coupled isotopic and process‐based modeling of gaseous nitrogen losses from tropical rain forests
Authors: Bai Edith , Houlton Benjamin Z.
Published: May 2009

Gaseous nitrogen (N) losses remove fixed N from the biosphere and play an important role in regulating Earth's climate system. Current techniques for measuring gaseous N fluxes are still limited, however, and many uncertainties remain. We used the natural isotopes of N, 15N/14N, to constrain process‐based model (DAYCENT, the daily version of CENTURY) estimates of gaseous N emissions from terrestrial ecosystems. The isotope model considers two scenarios. In the first, soil 15N/14N is a linear function of a fraction of gaseous N losses. In the second, underexpression of denitrification's isotope effect is considered, and soil 15N/14N is determined by both the fraction of gaseous losses and the proportion of NO3− consumed locally by denitrification. We examined the coupled process‐ and isotope‐based model along two Hawaiian rain forest gradients which span a range of tropical climates, soil biogeochemical ages, and ecosystem 15N/14N. Under most conditions (mean annual precipitation (MAP) <4050 mm), modeled soil 15N/14N ratios agreed well with measurements (r2 = 0.89), consistent with full expression of denitrification's isotope effect (scenario 1). In very wet sites (MAP ≥ 4050 mm), locally complete NO3− consumption appears to lower the isotopic expression of denitrification at ecosystem levels, resulting in soil 15N/14N ratios that approach those of the N inputs (i.e., scenario 2). Replacing modeled gaseous N emissions with field‐based measures of oxidized N, gas fluxes (NOx + N2O) resulted in consistently lower estimates of soil 15N/14N ratios across the forests. This points to a missing gas N loss term (i.e., N2), inadequate coverage of spatial and temporal heterogeneity by empirical measures, or both. These results demonstrate the potential for soil N isotopes to constrain N gas fluxes at large geographic scales, providing a quantitative tracer of gaseous N emissions from land.
View‐angle consistency in reflectance, optical thickness and spherical albedo of marine water‐clouds over the northeastern Pacific through MISR‐MODIS fusion
Authors: Liang Lusheng , Di Girolamo Larry , Platnick Steven
Published: May 2009

View‐angle consistency in bidirectional reflectance factor (BRF), optical thickness and spherical albedo is examined for marine water clouds over a region of the northeastern Pacific using six years of fused Moderate Resolution Imaging Spectroradiometer (MODIS) and Multiangle Imaging SpectroRadiometer (MISR) data. Consistency is quantified by the root‐mean‐square of relative differences between MISR‐measured BRF and their plane‐parallel values and variation of plane‐parallel retrieved optical thickness and spherical albedo across multiple view‐angles. Probability distribution functions of consistency show that, for example, these clouds are angularly consistent within 5% in BRF, optical thickness and spherical albedo 72.2%, 39.0% and 81.1% of the time, respectively. We relate angular consistency to the spatial variability of nadir‐BRF, thus allowing us to potentially identify, with a prescribed confidence level, which MODIS microphysical retrievals within the MISR swath meet the plane‐parallel assumption to within any desired range in view‐angle consistency.
Theoretical study of new plasma structures in the low‐latitude ionosphere during a major magnetic storm
Authors: Lin C. H. , Richmond A. D. , Liu J. Y. , Bailey G. J. , Reinisch B. W.
Published: May 2009

Theoretical model simulations for an intense magnetic storm show the creation of a low‐latitude electron density arch aligned along the geomagnetic field created by strong uplift of the F2 layer that is driven by the penetration electric field. When the arch forms during the day, a new F2 layer is created at the original altitude by photoionization, and a density hole can be created between this new F2 layer and the arch. When the arch forms during the night, the F2 layer is not recreated and no hole forms. In a vertical profile of electron density, the daytime elevated ionospheric layer can appear distinctly from the recreated F2 layer, in which case the elevated layer is called the F3 layer. A latitude cut through the night‐side arch shows the characteristics of an equatorial electron density trough, bounded to the north and south by enhanced densities associated with plasma that has diffused down along the geomagnetic field from the elevated layer. It is pointed out that the signature of the night‐side arch has been seen in low Earth orbit spacecraft data, but has not been previously associated with an arch structure.
Using τc to estimate magnitude for earthquake early warning and effects of near‐field terms
Authors: Yamada Masumi , Mori Jim
Published: May 2009

This paper analyzes strong motion records of 24 large earthquakes to investigate the relationship between τc (the period parameter of the first motion) and moment magnitude. The records of some of the large‐magnitude events very close to the source include large near‐field terms. Therefore, if we include the data with large near‐field terms, we may overestimate the final size of the magnitude. We identified records with large near‐field terms and did not include these data in processing the records to compute τc for each event. Our analysis shows that the value of τc is between the earthquake corner period and the period determined by the record duration τ0. If the magnitude is less than 6, τc closely approximates the corner period, whereas τc for larger earthquakes depends on the rupture process and location of asperity. τc for large earthquakes provides a lower bound on the event magnitude and approaches the corner period if a longer record is used. We also propose a method to classify the records with and without large near‐field terms. If the peak displacement amplitude for the first 3 s (Pd3) exceeds 1 cm and τc exceeds 2 s, the record is more likely to include large near‐field terms. For the purpose of quick onsite warnings, stations observing large near‐field terms provide valuable information. Large near‐field terms can be observed only if the magnitude is large and the epicentral distance is small. Therefore, if the displacement exceeds a threshold (e.g., Pd = 0.5 cm), the ground motion at the site would likely become very large. This criterion will help to issue warnings to the blind zone, which is the region where there is insufficient time to issue a warning before the strong shaking arrives.
Formation of ozone and growth of aerosols in young smoke plumes from biomass burning: 1. Lagrangian parcel studies
Authors: Alvarado Matthew James , Prinn Ronald G.
Published: May 2009

We have developed a new model of the gas‐ and aerosol‐phase chemistry of biomass burning smoke plumes called Aerosol Simulation Program (ASP). Here we use ASP combined with a Lagrangian parcel model to simulate the chemistry in smoke plumes from three fires: the Otavi savannah fire in Namibia, an Alaska boreal forest fire, and the Timbavati savannah fire. Our model explained the observations of ozone in the Otavi and Alaska plumes fairly well, but our initial model simulation of the Timbavati plume underestimated the concentrations of ozone, OH, and secondary aerosol matter. The Timbavati simulation agrees with observations if we increase OH to equal its observed levels. Heterogeneous reactions of NO2 and SO2 could explain the needed higher concentrations of OH and the rapid formation of ozone, nitrate, and sulfate in the smoke plume if the uptake coefficients on smoke aerosols are large (O(10−3) and O(10−4), respectively). Uncharacterized organic species in the smoke plume were likely responsible for the rapid formation of aerosol organic carbon. The changes in the aerosol size distribution were dominated by plume dilution and condensational growth. The single scattering albedo of the modeled smoke increases from 0.866 to 0.902 over 1 h of aging. The change in aerosol scattering with relative humidity for the modeled fresh smoke matches observations up to 66% RH, but the model greatly overestimates the humidification factor at 80% RH (2.88 versus an observed value of 1.70–1.79). For the aged smoke, the modeled humidification factor is 1.22, slightly below the observed value of 1.40.
Disturbance impacts on mercury dynamics in northern Gulf of Mexico sediments
Authors: Liu B. , Schaider L. A. , Mason R. P. , Bank M. S. , Rabalais N. N. , Swarzenski P. W. , Shine J. P. , Hollweg T. , Senn D. B.
Published: May 2009

We evaluated the impacts of physical disturbance on sediment Hg biogeochemistry in the northern Gulf of Mexico by exploring changes in Hg abundance and speciation in cores collected between July 2005 and July 2006, a time period that included the passages of Hurricanes Katrina and Rita in this region. Comparisons across space and time reveal large changes in sediment characteristics, both with respect to Hg biogeochemistry and other measures of sediment composition, that indicate substantial disturbance. While the degree of disturbance varied between stations, at sites that clearly received new surface deposits considerable increases in OC and total Hg were observed, along with shifts in major element composition. At the station closest to Hurricane Katrina's track (station A′2), 210Pb levels are consistent with the episodic deposition of >10 cm of sediments. These surface sediments (0–10 cm) at A′2 had the highest %MeHg of all stations and all dates, suggesting that the disturbance resulted initially in increased net methylation. While the observed disturbances elsewhere could not in all cases be definitively linked to hurricane activities, the substantial thickness of deposits (>10 cm) at multiple sites is consistent with a major event, and the similarity in the deposits' chemical fingerprint across all impacted sites suggests similar sources or processes. We estimate that the two hurricanes redistributed approximately 5 times the annual Hg input from the Mississippi‐Atchafalaya River system and atmospheric deposition. These observations highlight the need to consider the effects of major disturbances on the biogeochemical cycling of Hg in coastal systems.
Evaluation of groundwater storage monitoring with the GRACE satellite: Case study of the High Plains aquifer, central United States
Authors: Strassberg Gil , Scanlon Bridget R. , Chambers Don
Published: May 2009

Water scarcity is a critical issue in semiarid regions; however, regional groundwater monitoring is extremely limited. This study evaluates the ability of the GRACE satellites to monitor groundwater storage in the semiarid High Plains aquifer, United States (450,000 km2 area), which is subjected to intense irrigation. GRACE‐derived terrestrial water storage (TWS) is highly correlated with the sum of soil moisture (SM) and groundwater storage (GWS) (R = 0.96 for in situ measured SM from 78 stations and R = 0.95 for simulated SM with the Noah land surface model with root‐mean‐square difference of 38 mm and 36 mm, respectively). Correlation between seasonal GWS changes calculated from GRACE TWS minus SM and measured GWS (∼1000 wells per season) is also high (R = 0.73 for in situ SM and R = 0.72 for simulated SM). Variability in SM is mostly restricted to the upper 2 m of the soil. Monitored SM compared favorably with simulated SM (R = 0.82). Study results show the potential for using GRACE gravity measurements to monitor TWS and GWS over large semiarid regions subjected to intense irrigation.
A new wireless underground network system for continuous monitoring of soil water contents
Authors: Ritsema Coen J. , Kuipers Henk , Kleiboer Leon , van den Elsen Erik , Oostindie Klaas , Wesseling Jan G. , Wolthuis Jan‐Willem , Havinga Paul
Published: May 2009

A new stand‐alone wireless embedded network system has been developed recently for continuous monitoring of soil water contents at multiple depths. This paper presents information on the technical aspects of the system, including the applied sensor technology, the wireless communication protocols, the gateway station for data collection, and data transfer to an end user Web page for disseminating results to targeted audiences. Results from the first test of the network system are presented and discussed, including lessons learned so far and actions to be undertaken in the near future to improve and enhance the operability of this innovative measurement approach.
Effective two‐phase flow in heterogeneous media under temporal pressure fluctuations
Authors: Bolster Diogo , Dentz Marco , Carrera Jesus
Published: May 2009

We study the combined effect of spatial heterogeneity and temporal pressure fluctuations on the dispersion of the saturation of a displacing fluid during injection into an immiscible one. In a stochastic modeling framework, we define two different dispersion quantities, one which measures the front uncertainty due to temporal pressure fluctuations and another one which quantifies the actual spreading and dispersion of the saturation front in a typical medium realization. We derive an effective large‐scale flow equation for the saturation of the displacing fluid that is characterized by a nonlocal dispersive flux term. From the latter we derive measures for the spread of the saturation front due to spatiotemporal fluctuations. Our analysis demonstrates that temporal fluctuations enhance the front uncertainty but not the average spreading of the saturation front. The analytical developments are complemented by numerical simulations of the full two‐phase flow problem. Correct assessment of the spread of the saturation front is of importance to several applications, including the assessment of the sequestration potential of a carbon dioxide storage site, for example. Spreading enhances the surface area between the fluids, which in turn enhances the dissolution and entrapment efficiency. The latter facilitates reactions and thus the sequestration of CO2 in stable forms. Our study provides a theoretical basis for the design of injection strategies to optimize dispersion and to minimize uncertainty of the saturation front.
Seismic detection of island trapped sea waves from a landslide‐generated tsunami at Stromboli (Italy)
Authors: Pino Nicola Alessandro , Boschi Enzo
Published: May 2009

We analyzed short period seismograms recorded at Stromboli, searching for a possible signature of the tsunami following the two landslides occurred on the island on 30 December 2002. By taking advantage of their close occurrence in space and time, we recognized the seismic mark of clock‐ and counterclockwise tsunami waves trapped by the island coast. The most energetic direct arrivals, running around the island in the two opposite directions, traveled with an average velocity of about 12 m/s, while the waves that traveled more than once around the island display a slightly higher velocity. These observations represent the first instrumental evidence of trapped waves around pseudo‐conical islands and demonstrate the possibility of using coastal seismic stations for monitoring tsunami propagation. Our results provide important constraints for early warning of tsunami generated at Stromboli in the Sciara del Fuoco area, where considerable landslides are known to have occurred in the past.
Analysis of the influence of Saharan air layer on tropical cyclone intensity using AIRS/Aqua data
Authors: Shu Shoujuan , Wu Liguang
Published: May 2009

How the Saharan air layer (SAL) affects tropical cyclone intensity in the North Atlantic Ocean is an issue in debate. A composite study of 274 cases from 37 named tropical cyclones that formed during the period 2005–2007 is conducted using AIRS relative humidity between 600–700 hPa. Typically the dry SAL air is first observed within 1000 km north of the tropical cyclone center and then intrudes southward and towards the inner region of tropical cyclones along the cyclonic flow. This study provides evidence that the SAL can affect tropical cyclone intensity in both favorably and unfavorably manners by intensifying tropical cyclones when it is first found mostly in the northwest quadrant and then weakening tropical cyclones when its dry air intrudes within 360 km of the tropical cyclone center, mostly in the southwest and southeast quadrants. It appears that the SAL is favorable for the initial development of tropical cyclones but unfavorable for their subsequent intensification.
Impact‐induced thermal effects in the lunar and Mercurian regoliths
Authors: Cintala Mark J.
Published: May 2009

While the Moon and Mercury are similar objects in a geomorphologic sense, they also possess important differences, particularly in the context of small‐scale impact phenomena. Not only is the surface of Mercury notably hotter than that of the Moon, but the impact flux is also more intense at Mercury due to higher impact velocities and a greater spatial density of micrometeoroids. By extrapolating the terrestrial micrometeoroid flux to the Moon and Mercury, it is found that the impact rate at Mercury is 5.5 times greater and the mean impact velocity more than 60 percent higher than at the Moon. A model of impact melting and vaporization applied to the lunar and mercurian environments indicates that almost 14 times more impact melt and over 20 times more vapor are generated per unit time in the mercurian regolith. Although the surface temperature plays a role in determining the melt and vapor volumes, the difference in impact velocity appears to be markedly more important. “Average” craters formed by identical projectiles under the two velocity distributions on the two planets should be very similar in size, because differences in the kinetic energy of the “average” impactors will be offset by the differences in gravitational acceleration. As a result, variations in regolith mixing should depend more on the actual impact rates than on disparities in excavated volumes. Each “average” impact on Mercury, however, will produce more than twice as much impact melt as its lunar counterpart, introducing more glass into the mercurian regolith. Although substantial quantities of impact vapor are produced on both planets, mixing of the regolith should occur quickly enough in each case to spread the deposited vapor over large surface areas; the resulting vapor coatings should be negligibly small for most purposes. A much larger agglutinate population should exist on Mercury, and individual agglutinates should be similar to those of the lunar highlands. Reflectance spectra and visual albedos indicate that the mercurian crust possesses relatively small quantities of Fe, perhaps similar to those of Apollo 16 light‐ and dark‐matrix breccias. Laboratory studies have demonstrated that, as the magnetic fractions (which are correlated with agglutinate abundances) of soils derived from these breccias increase, the differences in 0.565‐mm (visible light) reflectivity between the soils diminish. Should the regional variations in Fe‐content of the mercurian crust be similar to those of these Apollo 16 samples, then the intense agglutination environment could account for the lack of optical contrast across the mercurian surface. At the same time, the very large fraction of impact glass in the regolith would imply that most pyroxenes have been fused and incorporated into these glasses, seriously attenuating the Fe2+crystal‐field absorption near 0.9‐mm. Supporting this picture are the most recently published spectral observations of Mercury, which provide little or no evidence of such an absorption feature.
An experimental study of aeolian structures on Venus
Authors: Marshall John R. , Greeley Ronald
Published: May 2009

Experiments to simulate the formation of aeolian bed forms on Venus show that a high‐density atmosphere produces small transverse bed forms with dimensionless similarities to terrestrial dunes but with both dimensional and behavioral similarities to subaqueous current ripples. Their development is influenced by wind speed, particle size, and atmospheric density. Although aeolian bed forms should be observed at all elevations on Venus, their optimum expression is compatible with the lowest elevations where atmospheric pressure is greatest. Their development is relatively unhindered by the presence of dense grains, the lack of sorting in source sediment from which they form, or the addition of cohesive dust. Small (∼10 cm) bed forms are efficient in sorting materials either by density or particle size. Bed forms developed in the limited size of the wind tunnel are probably representative of small bed forms on Venus; considerations suggest that bed forms on Venus may grow to larger sizes. Discovery of dune fields on Magellan images of Venus support this prediction.