bluuebunny/crossref_metadata_2025 huggingface dataset:
Interoperable IPv6 Sensor Networking over PLC and RF Media
Authors: Chauvenet Cedric , Tourancheau Bernard , Genon-Catalot Denis , Goudet Pierre-Emmanuel , Pouillot Mathieu
Published: February 2011

The evolution of technology has made the connection of all types of devices to IP networks possible. In this paper, the authors investigate the possible usage of IPv6 in sensor networks connected through the Power Line Communication (PLC) non-wireless medium and demonstrate possible interoperability. This work is based on the adaptation of the IEEE 802.15.4 standard protocol constrained by the low-power, lossy and low data-rate context of PLC transceiver that uses pulse modulation. The aim is to provide interoperability features with other media using a robust and reliable communication stack. The target application of such results ranges from smart metering and environment monitoring to home control and urban area energy efficiency applications. This paper proposes the first adaptation of the IEEE 802.15.4 standard commons for the PLC medium. Following this standard interface, the authors demonstrate data communication on PLC with low power energy requirement using the pulse PLC physical layer. This paper also presents an initial implementation of the Routing Protocol for Low power and lossy networks (RPL) setup proposed by the IETF working group. In this context, the authors demonstrate interoperability in a testbed between PLC and Wireless Sensor Networks (WSN).
Predictive Dynamic Uplink /Downlink Resource Reservation for Vertical Handoff Optimization in 4G Networks
Authors: Trabelsi Sihem , Boudriga Noureddine
Published: February 2011

The fourth generation of mobile wireless networks (4G) is expected to be the most promising architecture for QoS provision due to its scalability, convenience for mobility support and capability of interworking heterogeneous radio access networks, which ensure both session continuity and QoS support. One major design issue of the 4G is the support of optimized handoff functionalities. More specifically, total disruption during a handoff should be minimized and its complexity hidden to end users. In this regard, the authors focus on developing new dynamic predictive resource reservation schemes in 4G for both uplink and downlink to maximize handoff success probability. The paper illustrates how to reserve radio resources according to future mobile terminal location expressed in a probabilistic way, to load conditions or target Base Station/Access point BS/AP and to the specificity of the data structure of each access network. Different resource reservation algorithms are devised. The objective is to efficiently utilize wireless radio resources, enhance the handoff performances and improve system performance.
Antecedents of Security Pillars in E-Commerce Applications
Authors: Shaqrah Amin A.
Published: February 2011

This paper investigates the relationship between internet security and e-business competence at banking and exchange firms in Jordan. The proposed conceptual model examines the antecedents and consequences of e-business competence and tests its empirical validity. The sample of 152 banking and exchange firms tests the posited structural equation model. The results consistently support the validity of the proposed conceptual model, the results also found that organizations realize the importance of e- business and are willing to proceed further with e-business. Beyond concerns about internet security, their awareness of security hazards and internet performance is minimal. The author concludes that the public awareness of ICT in general is low. In light of the data collected, the author makes recommendations for the interested authorities to improve e-business in Jordan.
Design Factors for Effective Science Simulations
Authors: Plass Jan L. , Homer Bruce D. , Milne Catherine , Jordan Trace , Kalyuga Slava , Kim Minchi , Lee Hyunjeong
Published: February 2011

We propose that the effectiveness of simulations for science education depends on design features such as the type of representation chosen to depict key concepts. We hypothesize that the addition of iconic representations to simulations can help novice learners interpret the visual simulation interface and improve cognitive learning outcomes as well as learners’ self-efficacy. This hypothesis was tested in two experiments with high school chemistry students. The studies examined the effects of representation type (symbolic versus iconic), prior knowledge, and spatial ability on comprehension, transfer, and self-efficacy under low cognitive load (Study 1, N=80) and high cognitive load conditions (Study 2, N=91). Results supported our hypotheses that design features such as the addition of iconic representations can help scaffold students’ comprehension of science simulations, and that this effect was strongest for learners with low prior knowledge. Adding icons also improved learners’ general self-efficacy.
Becoming Citizens Through Game-Based Learning
Authors: Chee Yam San , Loke Swee Kin , Tan Ek Ming
Published: February 2011

In this article, we share a model of game-based learning for use in the context of classroom learning in school. The model is based on the dialectic interaction between game play and dialogic engagement with peers and teacher on one hand and a developmental trajectory of competence-through-performance on the other. It is instantiated in the context of a learning program related to citizenship education using the computer game Space Station Leonis. We argue for the importance of values in all learning, based upon a theory of becoming citizens that is founded on process philosophy. We relate values to dispositions, as articulated manifestations of values, and describe how the Leonis learning program helps to achieve dispositional shifts befitting citizenship education in a globalized and multi-cultural world.
The Play of Persuasion
Authors: Fortugno Nicholas
Published: February 2011

Game designer Nick Fortungno’s keynote speech at the Meaningful Play conference talked about the conundrum of whether serious games can or even should be fun. Fortugno looks back at historical works of popular culture that exerted transformative effects on society. He examines three current persuasive games and offers his thoughts on what it will take for a game to achieve societal transformation.
Adaptive Interactive Narrative Model to Teach Ethics
Authors: Hodhod Rania , Kudenko Daniel , Cairns Paul
Published: February 2011

Promoting ethical, responsible, and caring young people is a perennial aim of education. Efforts have been made to find ways of teaching other than traditional ones like games and role play. Narrative-based computer games are engaging learning platforms that allow collaboration of humans and computers in the creation of innovative experiences. In this paper, the authors examine the design of an adaptive, interactive narrative model that uses a student model to provide an individualized story-path and an individualized learning process. In this regard, the authors comprise strong learning objectives underpinned by effective story telling. The adaptive narrative model has been deployed in the educational game environment, AEINS, along with the use of the Socratic Method and pedagogical agents to support teaching in the ethics domain. Evaluation results indicate the usefulness of the design and provide evidence on the development of moral reasoning and the transfer of moral virtues to its users.
Towards Games for Knowledge Acquisition and Modeling
Authors: Hoppenbrouwers Stijn , Schotten Bart , Lucas Peter
Published: February 2011

Many model-based methods in AI require formal representation of knowledge as input. For the acquisition of highly structured, domain-specific knowledge, machine learning techniques still fall short, and knowledge elicitation and modelling is then the standard. However, obtaining formal models from informants who have few or no formal skills is a non-trivial aspect of knowledge acquisition, which can be viewed as an instance of the well-known “knowledge acquisition bottleneck”. Based on the authors’ work in conceptual modelling and method engineering, this paper casts methods for knowledge modelling in the framework of games. The resulting games-for-modelling approach is illustrated by a first prototype of such a game. The authors’ long-term goal is to lower the threshold for formal knowledge acquisition and modelling.
Computational and Experimental Analysis Reveals a Requirement for Eosinophil-Derived IL-13 for the Development of Allergic Airway Responses in C57BL/6 Mice
Authors: Walsh Elizabeth R. , Thakar Juilee , Stokes Kindra , Huang Fei , Albert Reka , August Avery
Published: February 2011

Eosinophils are found in the lungs of humans with allergic asthma, as well as in the lungs of animals in models of this disease. Increasing evidence suggests that these cells are integral to the development of allergic asthma in C57BL/6 mice. However, the specific function of eosinophils that is required for this event is not known. In this study, we experimentally validate a dynamic computational model and perform follow-up experimental observations to determine the mechanism of eosinophil modulation of T cell recruitment to the lung during development of allergic asthma. We find that eosinophils deficient in IL-13 were unable to rescue airway hyperresponsiveness, T cell recruitment to the lungs, and Th2 cytokine/chemokine production in ΔdblGATA eosinophil-deficient mice, even if Th2 cells were present. However, eosinophil-derived IL-13 alone was unable to rescue allergic asthma responses in the absence of competence of other IL-13–producing cells. We further computationally investigate the role of other cell types in the production of IL-13, which led to the various predictions including early and late pulses of IL-13 during airway hyperresponsiveness. These experiments suggest that eosinophils and T cells have an interdependent relationship, centered on IL-13, which regulates T cell recruitment to the lung and development of allergic asthma.
Human TMEM30a Promotes Uptake of Antitumor and Bioactive Choline Phospholipids into Mammalian Cells
Authors: Chen Rui , Brady Erin , McIntyre Thomas M.
Published: February 2011

Antitumor alkylphospholipids initiate apoptosis in transformed HL-60 and Jurkat cells while sparing their progenitors. 1-O-Alkyl-2-carboxymethyl-sn-glycero-3-phosphocholine (Edelfosine) like other short-chained phospholipids—inflammatory platelet-activating factor (PAF) and apoptotic oxidatively truncated phospholipids—are proposed to have intracellular sites of action, yet a conduit for these choline phospholipids into mammalian cells is undefined. Edelfosine is also accumulated by Saccharomyces cerevisiae in a process requiring the membrane protein Lem3p, and the human genome contains a Lem3p homolog TMEM30a. We show that import of choline phospholipids into S. cerevisiae ΔLem3 is partially reconstituted by human TMEM30a and by Lem3p-TMEM30a chimeras, showing the proteins are orthologous. TMEM30a–GFP chimeras expressed in mammalian cells localized in plasma membranes, as well as internal organelles, and ectopic TMEM30a expression promoted uptake of exogenous choline and ethanolamine phospholipids. Short hairpin RNA knockdown of TMEM30a reduced fluorescent choline phospholipid and [3H]PAF import. This knockdown also reduced mitochondrial depolarization from exogenous Edelfosine or the mitotoxic oxidatively truncated phospholipid azelaoyl phosphatidylcholine, and the knockdown reduced apoptosis in response to these two phospholipids. These results show that extracellular choline phospholipids with short sn-2 residues can have intracellular roles and sites of metabolism because they are transport substrates for a TMEM30a phospholipid import system. Variation in this mechanism could limit sensitivity to short chain choline phospholipids such as Edelfosine, PAF, and proapoptotic phospholipids.
Coronin 1-Mediated Naive T Cell Survival Is Essential for the Development of Autoimmune Encephalomyelitis
Authors: Siegmund Kerstin , Zeis Thomas , Kunz Gabriele , Rolink Ton , Schaeren-Wiemers Nicole , Pieters Jean
Published: February 2011

Autoimmune encephalomyelitis is a disease of the CNS that can develop when an initial peripheral inflammatory stimulus is followed by infiltration and reactivation of T lymphocytes in the CNS. We report a crucial role for coronin 1, which is essential for maintenance of the naive T cell pool, for the development of murine experimental autoimmune encephalomyelitis (EAE), a model for multiple sclerosis. In the absence of coronin 1, immunization with myelin oligoglycoprotein (MOG35–55) peptide largely failed to induce EAE symptoms, despite normal mobilization of leukocyte subsets in the blood, as well as effector cytokine expression comparable with wild-type T cells on polyclonal stimulation. Susceptibility of coronin 1-deficient mice to EAE induction was restored by transfer of wild-type CD4+ T cells, suggesting that the observed resistance of coronin 1-deficient mice to EAE development is T cell intrinsic. Importantly, although coronin 1-deficient regulatory T cells (Tregs) showed a suppressor activity comparable with wild-type Tregs, Treg depletion failed to restore EAE development in coronin 1-deficient animals. These results suggest a hitherto unrecognized role of naive T cells in the development of autoimmune encephalomyelitis and reveal coronin 1 as a crucial modulator of EAE induction.
No Association between Variant N-acetyltransferase Genes, Cigarette Smoking and Prostate Cancer Susceptibility Among Men of African Descent
Authors: Kidd La Creis Renee , VanCleave Tiva T. , Doll Mark A. , Srivastava Daya S. , Thacker Brandon , Komolafe Oyeyemi , Pihur Vasyl , Brock Guy N. , Hein David W.
Published: February 2011

Objective

We evaluated the individual and combination effects of NAT1, NAT2 and tobacco smoking in a case-control study of 219 incident prostate cancer (PCa) cases and 555 disease-free men.

Methods

Allelic discriminations for 15 NAT1 and NAT2 loci were detected in germ-line DNA samples using Taqman polymerase chain reaction (PCR) assays. Single gene, gene-gene and gene-smoking interactions were analyzed using logistic regression models and multi-factor dimensionality reduction (MDR) adjusted for age and subpopulation stratification. MDR involves a rigorous algorithm that has ample statistical power to assess and visualize gene-gene and gene-environment interactions using relatively small samples sizes (i.e., 200 cases and 200 controls).

Results

Despite the relatively high prevalence of NAT1*10/*10 (40.1%), NAT2 slow (30.6%), and NAT2 very slow acetylator genotypes (10.1%) among our study participants, these putative risk factors did not individually or jointly increase PCa risk among all subjects or a subset analysis restricted to tobacco smokers.

Conclusion

Our data do not support the use of N-acetyltransferase genetic susceptibilities as PCa risk factors among men of African descent; however, subsequent studies in larger sample populations are needed to confirm this finding.
A Review of Sevelamer Hydrochloride in End-Stage Renal Disease Patients on Dialysis
Authors: Spasovski Goce
Published: February 2011

It is known that in the presence of even subtle kidney dysfunction an intensive prevention of cardiovascular risk is required. Apart from the conventional factors which contribute to cardiovascular disease (CVD), there are also some specific conditions of the chronic kidney disease (CKD) population such as oxidative stress of uremia and dialysis (D). However, hyperphosphatemia, hypercalcemia, and elevated calcium-phosphorus product remain as major contributors to the development of vascular calcification (VC) in this population, as part of the systemic complication known as mineral and bone disorders (MBD) in CKD patients. Importantly, the retention of phosphate remains as main culprit in the pathogenesis of CKD–-MBD. Over the years, various treatment options for phosphate removal and controlling mineral metabolism, bone health, VC and CVD have failed, mainly through an over-suppression of PTH, development of ABD and promotion of VC and mortality.

Although KDOQI and KDIGO published CKD–-MBD guidelines has clearly stated where calcium-based phosphate binders should not be used in D patients (hypercalcemia and low PTH) and where non calcium-containing phosphate binders are preferred (patients with severe vascular and/or other soft tissue calcifications), the greatest controversy and disagreements within the nephrological community still exists upon the cost-effectiveness of non calcium binder (sevelamer) use. Indeed, despite the evidence and recognised trend towards both a decrease in VC and CVD associated with sevelamer use, it is still an ongoing matter of debate. The magnitude of this controversy is increased when the issue of advanced medical and/or budgetary evaluation related to the implementation of clinical guidelines for CKD–-MBD treatment is considered. Despite advocated use of sevelamer across a range of common clinical scenarios in CKD, its widespread utilization is challenged as exceeding what would usually be considered good value for money. If so, it is questionable whether the recommendations and suggestions from the guidelines should be followed, and further, do we need guidelines and innovative drugs for treatment of hyperphosphatemia? While awaiting the answer, as clinicians we should proceed with a treatment to “do no harm”, trying to at least limit the calcium exposure of our dialysis patients.
Phylogenetic Analysis of the 56 kDa Protein Genes of Orientia tsutsugamushi in Southwest Area of Korea
Authors: Lee Yu-Mi , Kim Dong-Min , Lee Seung-Hyun , Jang Mi-Sun , Neupane Ganesh Prasad
Published: February 2011

This study was conducted to determine which genotypes were present in southwestern Korea. Nested polymerase chain reaction (PCR) and DNA sequence analysis targeting the Orientia tsutsugamushi-specific 56-kDa protein gene was performed with samples of blood and eschar. Of the 69 PCR-positive samples, 61 clustered with the Boryong previously isolated in Korea. CUH 4-6 had sequence homology of 100% with Kato, and CUH 4-3 had homology of 99.8% with Kato and formed the Kato cluster. CUH 4-57, CUH 4-31, CUH 4-142, and CUH 4-324 formed a Kawasaki cluster. CUH 4-271 had sequence homology of 100% with Jecheon and formed a Karp cluster. CUH 4-117 had homology of 99.8% with Neimeng-65, and Gilliam cluster. The most common genotype of O. tsutsugamushi in the southwestern part of Korea is the Boryong genotype. We also identified O. tsutsugamushi of the Kato, Neimeng-65 and Kawasaki genotypes, which had not been identified before in Korea.
Factors Influencing Dengue Virus Isolation by C6/36 Cell Culture and Mosquito Inoculation of Nested PCR-Positive Clinical Samples
Authors: Jarman Richard G. , Nisalak Ananda , Anderson Kathryn B. , Klungthong Chonticha , Thaisomboonsuk Butsaya , Kaneechit Winai , Kalayanarooj Siripen , Gibbons Robert V.
Published: February 2011

Dengue viral isolation is necessary for definitive diagnosis, pathogenesis and evolutionary research, vaccine candidates, and diagnostic materials. Using standardized techniques, we analyzed isolation rates of 1,544 randomly selected polymerase chain reaction (PCR)-positive samples, representing all four dengue serotypes, from patients with serologically confirmed dengue infections and evaluated whether clinical and laboratory results could be predictive of isolation using standard and mosquito isolation techniques. Viruses were isolated from 62.5% of the samples by direct application to C6/36 cells and increased to 79.4% when amplifying C6/36 negative samples by intrathorasic inoculation in Toxyrhynchites splendens mosquitoes. High viremia, measured by reverse transcriptase (RT)-PCR, was a strong predictor for viral isolation by either method. Isolation was most successful in samples collected early in the disease, had low antibody levels, temperatures greater than 38°C, and had a final clinical diagnosis of dengue fever. Dengue serotypes also played a role in the success of viral isolation.
The Effects of Informational Interventions on Household Water Management, Hygiene Behaviors, Stored Drinking Water Quality, and Hand Contamination in Peri-Urban Tanzania
Authors: Davis Jennifer , Pickering Amy J. , Rogers Kirsten , Mamuya Simon , Boehm Alexandria B.
Published: February 2011

Safe water storage and hand hygiene have been shown to reduce fecal contamination and improve health in experimental settings; however, triggering and sustaining such behaviors is challenging. This study investigates the extent to which personalized information about Escherichia coli contamination of stored water and hands influenced knowledge, reported behaviors, and subsequent contamination levels among 334 households with less than 5-year-old children in peri-urban Dar es Salaam, Tanzania. One-quarter of the study participants received information about strategies to reduce risk of water- and sanitation-related illness. Respondents in another three study cohorts received this same information, along with their household's water and/or hand-rinse test results. Findings from this study suggest that additional work is needed to elucidate the conditions under which such testing represents a cost-effective strategy to motivate improved household water management and hand hygiene.
Regional Differences in the Association Between Land Cover and West Nile Virus Disease Incidence in Humans in the United States
Authors: Bowden Sarah E. , Magori Krisztian , Drake John M.
Published: February 2011

West Nile virus (WNV) is generally considered to be an urban pathogen in the United States, but studies associating land cover and disease incidence, seroprevalence, or infection rate in humans, birds, domesticated and wild mammals, and mosquitoes report varying and sometimes contradictory results at an array of spatial extents. Human infection can provide insight about basic transmission activity; therefore, we analyzed data on the incidence of WNV disease in humans to obtain a comprehensive picture of how human disease and land cover type are associated across the United States. Human WNV disease incidence in Northeastern regions was positively associated with urban land covers, whereas incidence in the Western United States was positively associated with agricultural land covers. We suggest that these regional associations are explained by the geographic distributions of prominent WNV vectors: Culex pipiens complex (including Cx. pipiens and Cx. quinquefasciatus) in the Northeast and Cx. tarsalis in the Western United States.
Burkholderia pseudomallei Antibodies in Individuals Living in Endemic Regions in Northeastern Brazil
Authors: Rolim Dionne Bezerra , Vilar Dina Cortez F. L. , de Góes Cavalcanti Luciano Pamplona , Freitas Liara B. N. , Inglis Timothy J. J. , Nobre Rodrigues Jorge Luiz , Nagao-Dias Aparecida Tiemi
Published: February 2011

A seroepidemiological investigation was conducted among the population of two municipalities in Northeastern Brazil. Immunoglobulin M (IgM) and IgG antibodies to Burkholderia pseudomallei were positive in 51.27% (161 in 317 samples) and 58.49% (186), respectively. IgM titers were higher in children than in adults. On the contrary, IgG increased progressively with age. We observed a significant association between agricultural occupation and raised IgM titers (P < 0.005) and IgG titers (P < 0.001), and between construction workers and raised IgG titers (P = 0.005). Antibody IgG avidities did not correlate with age. The highest titers of antibodies (1/800) showed the highest antibody avidity indexes (P < 0.01). Most of the serum samples recognized 45-kDa and 200-kDa bands by IgG1 and IgG2 subclasses. Our study showed a high seropositivity among individuals living in endemic regions of the state of Ceará, and highlights the need for further surveillance close to water courses such as dams and rivers in Northeastern Brazil.
What Is AIDS in the Amazon and the Guianas? Establishing the Burden of Disseminated Histoplasmosis
Authors: Nacher Mathieu , Adenis Antoine , Adriouch Leila , Dufour Julie , Papot Emmanuelle , Hanf Matthieu , Vantilcke Vincent , Calvez Mélanie , Aznar Christine , Carme Bernard , Couppié Pierre
Published: February 2011

The pathogen ecology of Amazonian regions may lead to specific differences in the most frequent clinical presentations of acquired immunodeficiency syndrome (AIDS). A retrospective cohort study was thus conducted to describe the main AIDS-defining events in French Guiana. Disseminated histoplasmosis was the most frequent opportunistic infection (15.4/1000 person years).
A Pentaplex Real-Time Polymerase Chain Reaction Assay for Detection of Four Species of Soil-Transmitted Helminths
Authors: Basuni Madihah , Muhi Jamail , Othman Nurulhasanah , Verweij Jaco J. , Ahmad Maimunah , Miswan Noorizan , Rahumatullah Anizah , Aziz Farhanah Abdul , Zainudin Nurul Shazalina , Noordin Rahmah
Published: February 2011

Soil-transmitted helminth infections remain a major public health burden in low- and middle-income countries. The traditional diagnosis by microscopic examination of fecal samples is insensitive and time-consuming. In this study, a pentaplex real-time polymerase chain reaction (PCR) was evaluated for the simultaneous detection of Ancylostoma, Necator americanus, Ascaris lumbricoides, and Strongyloides stercoralis. The results were compared with those obtained by conventional parasitological diagnostic methods. Real-time PCR was positive in 48 of 77 samples (62.3%) and microscopic examination was positive in six samples (7.8%) only (P < 0.05). In conclusion, the real-time PCR assay described in this study provides a specific and sensitive diagnostic tool for the detection of these four helminth species in epidemiological studies and monitoring of treatment programs.
Iron dissolution kinetics of mineral dust at low pH during simulated atmospheric processing
Authors: Shi Z. , Bonneville S. , Krom M. D. , Carslaw K. S. , Jickells T. D. , Baker A. R. , Benning L. G.
Published: February 2011

Abstract. We investigated the iron (Fe) dissolution kinetics of African (Tibesti) and Asian (Beijing) dust samples at acidic pH with the aim of reproducing the low pH conditions in atmospheric aerosols. The Beijing dust and three size fractions of the Tibesti dust (<20 μm: PM20; <10 μm: PM10; and <2.5 μm: PM2.5) were dissolved at pH 1, 2 and/or 3 for up to 1000 h. In the first 10 min, all dust samples underwent an extremely fast Fe solubilisation. Subsequently, the Fe dissolution proceeded at a much slower rate before reaching a stable dissolution plateau. The time-dependant Fe dissolution datasets were best described by a model comprising three acid-extractable Fe pools each dissolving according to first-order kinetics. The dissolution rate constant k (h−1) of each pool was independent of the source (Saharan or Asian) and the size (PM20, PM10 or PM2.5) of the dust but highly dependent on pH. The "fast" Fe pool had a k (25 h−1 at pH = 1) of a similar magnitude to "dry" ferrihydrite nanoparticles and/or poorly crystalline Fe(III) oxyhydroxide, while the "intermediate" and "slow" Fe pools had k values respectively 50–60 times and 3000–4000 times smaller than the "fast" pool. The "slow" Fe pool was likely to consist of both crystalline Fe oxide phases (i.e., goethite and/or hematite) and Fe contained in the clay minerals. The initial mass of the "fast", "intermediate" and "slow" Fe pools represented respectively about 0.5–2%, 1–3% and 15–40% of the total Fe in the dust samples. Furthermore, we showed that in systems with low dust/liquid ratios, Fe can be dissolved from all three pools, whereas at high dust/liquid ratios (e.g., in aerosols), sufficient Fe may be solubilised from the "fast" phase to dominate the Fe dissolved and to suppress the dissolution of Fe from the other Fe pools. These data demonstrated that dust/liquid ratio and pH are fundamental parameters controlling Fe dissolution kinetics in the dust. In order to reduce errors in atmospheric and climate models, these fundamental controlling factors need to be included.
Development of a simple unified volatility-based scheme (SUVS) for secondary organic aerosol formation using genetic algorithms
Authors: Xia A. G. , Stroud C. A. , Makar P. A.
Published: February 2011

Abstract. A new method is proposed to simplify complex atmospheric chemistry reaction schemes, while preserving SOA formation properties, using genetic algorithms. The method is first applied in this study to the gas-phase α-pinene oxidation scheme. The simple unified volatility-based scheme (SUVS) reflects the multi-generation evolution of chemical species from a near-explicit master chemical mechanism (MCM) and, at the same time, uses the volatility-basis set speciation for condensable products. The SUVS also unifies reactions between SOA precursors with different oxidants under different atmospheric conditions. A total of 412 unknown parameters (product yields of parameterized products, reaction rates, etc.) from the SUVS are estimated by using genetic algorithms operating on the detailed mechanism. The number of organic species was reduced from 310 in the detailed mechanism to 31 in the SUVS. Output species profiles, obtained from the original subset of the MCM reaction scheme for α-pinene oxidation, are reproduced with maximum fractional error at 0.10 for scenarios under a wide range of ambient HC/NOx conditions. Ultimately, the same SUVS with updated parameters could be used to describe the SOA formation from different precursors.
Characteristics, seasonality and sources of carbonaceous and ionic components in the tropical Indian aerosols
Authors: Pavuluri C. M. , Kawamura K. , Aggarwal S. G. , Swaminathan T.
Published: February 2011

Abstract. To better characterize South and Southeast Asian aerosols, PM10 samples collected from tropical Chennai, India (13.04° N; 80.17° E) were analyzed for carbonaceous and water-soluble ionic components. Concentration ranges of elemental carbon (EC) and organic carbon (OC) were 2.4–14 μg m−3 and 3.2–15.6 μg m−3 in winter samples whereas they were 1.1–2.5 μg m−3 and 4.1–17.6 μg m−3 in summer samples, respectively. Concentration of secondary organic carbon (SOC) retrieved from EC-tracer method was 4.6 ± 2.8 μg m−3 in winter and 4.3 ± 2.8 μg m−3 in summer. SO42- (8.8 ± 2.5 μg m−3 and 4.1 ± 2.7 μg m−3 in winter and summer, respectively) was found as the most abundant ionic species (57% on average, n = 49), followed by NH4+ (15%) > NO3− > Cl− > K+> Na+ > Ca2+ > MSA− > Mg2+. The mass fractions of EC, organic matter (OM) and ionic species varied seasonally, following the air mass trajectories and corresponding source strength. Based on mass concentration ratios of selected components and relations of EC and OC to marker species, we found that biofuel/biomass burning is the major source of atmospheric aerosols in South and Southeast Asia. The high concentrations of SOC and WSOC/OC ratios (ave. 0.45; n = 49) as well as good correlations between SOC and WSOC suggest that the secondary production of organic aerosols during long-range atmospheric transport is also significant in this region. This study provides the baseline data of carbonaceous aerosols for southern part of the Indian subcontinent.
Spatial distributions and seasonal cycles of aerosols in India and China seen in global climate-aerosol model
Authors: Henriksson S. V. , Laaksonen A. , Kerminen V.-M. , Räisänen P. , Järvinen H. , Sundström A.-M. , de Leeuw G.
Published: February 2011

Abstract. A climate-aerosol model is employed to study spatial and temporal variability of aerosol properties over India and China for recent (year 2006) and future conditions (year 2020) under different emission pathways. We present results for aerosol mass concentration in different size classes and optical properties for the five different aerosol species treated by the model. Aerosol mass concentration and optical depth have significant contributions from both anthropogenic and natural aerosols. Different species have maxima in different regions, with the highest anthropogenic aerosol concentrations found in Kolkata and elsewhere in the Ganges basin in India and on the northern part of the east coast and in the Sichuan basin in China. In India natural aerosols have a maximum in the summer due to higher wind speeds and anthropogenic aerosols have a maximum in the winter due to less efficient wet removal. Surface concentrations are also higher in winter due to the additional reason of lower average boundary layer height. In China seasonal cycles are weaker with natural aerosols having a maximum in the spring and sulfate contribution to the aerosol optical depth (AOD) being higher in the latter half of the year. MODIS AOD spatial distributions are reproduced well by the model, except for the Ganges valley with high absorption and for the Thar desert with high dust concentrations. Seasonal cycles compare well qualitatively with MODIS results. The larger AOD in China during the latter half of the year in the year 2006 simulation as compared to the MODIS data can be traced back to sulfate contribution with some contribution also from natural aerosols.
Non-stationarity of the quasi-perpendicular bow shock: comparison between Cluster observations and simulations
Authors: Comişel H. , Scholer M. , Soucek J. , Matsukiyo S.
Published: February 2011

Abstract. We have performed full particle electromagnetic simulations of a quasi-perpendicular shock. The shock parameters have been chosen to be appropriate for the quasi-perpendicular Earth's bow shock observed by Cluster on 24 January 2001 (Lobzin et al., 2007). We have performed two simulations with different ion to electron mass ratio: run 1 with mi/me=1840 and run 2 with mi/me=100. In run 1 the growth rate of the modified two-stream instability (MTSI) is large enough to get excited during the reflection and upstream gyration of part of the incident solar wind ions. The waves due to the MTSI are on the whistler mode branch and have downstream directed phase velocities in the shock frame. The Poynting flux (and wave group velocity) far upstream in the foot is also directed in the downstream direction. However, in the density and magnetic field compression region of the overshoot the waves are refracted and the Poynting flux in the shock frame is directed upstream. The MTSI is suppressed in the low mass ratio run 2. The low mass ratio run shows more clearly the non-stationarity of the shock with a larger time scale of the order of an inverse ion gyrofrequency (Ωci): the magnetic field profile flattens and steepens with a period of ~1.5Ωci−1. This non-stationarity is different from reformation seen in previous simulations of perpendicular or quasi-perpendicular shocks. Beginning with a sharp shock ramp the large electric field in the normal direction leads to high reflection rate of solar wind protons. As they propagate upstream, the ion bulk velocity decreases and the magnetic field increases in the foot, which results in a flattening of the magnetic field profile and in a decrease of the normal electric field. Subsequently the reflection rate decreases and the whole shock profile steepens again. Superimposed on this 'breathing' behavior are in the realistic mass ratio case the waves due to the MTSI. The simulations lead us to a re-interpretation of the 24 January 2001 bow shock observations reported by Lobzin et al. (2007). It is suggested that the high frequency waves observed in the magnetic field data are due to the MTSI and are not related to a nonlinear phase standing whistler. Different profiles at the different spacecraft are due to the non-stationary behavior on the larger time scale.
Temperature perturbations in the troposphere-stratosphere over Thumba (8.5° N, 76.9° E) during the solar eclipse 2009/2010
Authors: Subrahmanyam K. V. , Ramkumar G. , Kumar K. K. , Swain D. , Sunil Kumar S. V. , Das S. S. , Choudhary R. K. , Namboodiri K. V. S. , Uma K. N. , Veena S. B. , John S. R. , Babu A.
Published: February 2011

Abstract. Measurements of atmospheric temperature profiles in the troposphere and lower stratosphere were made over Thumba Equatorial Rocket Launching Station (TERLS) (8.5° N, 76.9° E) during a partial solar eclipse (22 July 2009) and an annular solar eclipse (15 January 2010). It was observed that during the partial solar eclipse, the temperature decreased by 2–3 °C in the vicinity of the tropopause and in the lower stratosphere the temperature increased by ~2.6 °C during the maximum phase of the partial solar eclipse. During the annular solar eclipse, a temperature reduction of ~2 °C was observed around the tropopause. This study also revealed a feature of delayed effect in the form of a very intense warming of ~8 °C at 18 km after about 4 h of the annular solar eclipse. The Cold-Point Tropopause (CPT) temperature increased slowly before the beginning of the eclipse (up to 10:00 IST) and during the maximum phase of the eclipse, the difference in CPT temperature and height was −3.5 °C and ~110 m, respectively, as that of the control day. After the four hours of the eclipse, the CPT height had decreased by ~1.7 km and the CPT temperature increased by ~4.6 °C. This is for the first time that the diurnal variation of the tropopause has been reported during a solar eclipse day. The present study, thus, provided an opportunity to investigate the temperature perturbations in the troposphere and lower stratosphere during a partial and annular solar eclipse. The highlight of the present results are (1) cooling of the entire troposphere and lower stratosphere during the maximum phase of annular solar eclipse, (2) an intense heating of the lower stratosphere by 8 °C after nearly four hours from the maximum phase of the annular eclipse, and (3) drastic variations in the diurnal evolution of the tropical tropopause characteristics. The cooling effect is attributed to the radiative response of the atmosphere to the solar eclipse, where as heating is attributed to the dynamical response of the atmosphere to the solar eclipse. These results may have important implications in understanding the response of the atmosphere to the radiative, as well as dynamical, perturbations caused by any celestial or terrestrial disturbances.
Evaluation of rainfall retrievals from SEVIRI reflectances over West Africa using TRMM-PR and CMORPH
Authors: Wolters E. L. A. , van den Hurk B. J. J. M. , Roebeling R. A.
Published: February 2011

Abstract. This paper describes the evaluation of the KNMI Cloud Physical Properties – Precipitation Properties (CPP-PP) algorithm over West Africa. The algorithm combines condensed water path (CWP), cloud phase (CPH), cloud particle effective radius (re), and cloud-top temperature (CTT) retrievals from visible, near-infrared and thermal infrared observations of the Spinning Enhanced Visible and Infrared Imager (SEVIRI) onboard the Meteosat Second Generation (MSG) satellites to estimate rain occurrence frequency and rain rate. For the 2005 and 2006 monsoon seasons, it is investigated whether the CPP-PP algorithm is capable of retrieving rain occurrence frequency and rain rate over West Africa with sufficient accuracy, using Tropical Monsoon Measurement Mission Precipitation Radar (TRMM-PR) as reference. As a second goal, it is assessed whether SEVIRI is capable of monitoring the seasonal and daytime evolution of rainfall during the West African monsoon (WAM), using Climate Prediction Center Morphing Technique (CMORPH) rainfall observations. The SEVIRI-detected rainfall area agrees well with TRMM-PR, with the areal extent of rainfall by SEVIRI being ~10% larger than from TRMM-PR. The mean retrieved rain rate from CPP-PP is about 8% higher than from TRMM-PR. Examination of the TRMM-PR and CPP-PP cumulative frequency distributions revealed that differences between CPP-PP and TRMM-PR are generally within +/−10%. Relative to the AMMA rain gauge observations, CPP-PP shows very good agreement up to 5 mm h−1. However, at higher rain rates (5–16 mm h−1) CPP-PP overestimates compared to the rain gauges. With respect to the second goal of this paper, it was shown that both the accumulated precipitation and the seasonal progression of rainfall throughout the WAM is in good agreement with CMORPH, although CPP-PP retrieves higher amounts in the coastal region of West Africa. Using latitudinal Hovmüller diagrams, a fair correspondence between CPP-PP and CMORPH was found, which is reflected by high correlation coefficients (~0.7) for both rain rate and rain occurrence frequency. The daytime cycle of rainfall from CPP-PP shows distinctly different patterns for three different regions in West Africa throughout the WAM, with a decrease in dynamical range of rainfall near the Inter Tropical Convergence Zone (ITCZ). The dynamical range as retrieved from CPP-PP is larger than that from CMORPH. It is suggested that this results from both the better spatio-temporal resolution of SEVIRI, as well as from thermal infrared radiances being partly used by CMORPH, which likely smoothes the daytime precipitation signal, especially in case of cold anvils from convective systems. The promising results show that the CPP-PP algorithm, taking advantage of the high spatio-temporal resolution of SEVIRI, is of added value for monitoring daytime precipitation patterns in tropical areas.
Global land-surface evaporation estimated from satellite-based observations
Authors: Miralles D. G. , Holmes T. R. H. , De Jeu R. A. M. , Gash J. H. , Meesters A. G. C. A. , Dolman A. J.
Published: February 2011

Abstract. This paper outlines a new strategy to derive evaporation from satellite observations. The approach uses a variety of satellite-sensor products to estimate daily evaporation at a global scale and 0.25 degree spatial resolution. Central to this methodology is the use of the Priestley and Taylor (PT) evaporation model. The minimalistic PT equation combines a small number of inputs, the majority of which can be detected from space. This reduces the number of variables that need to be modelled. Key distinguishing features of the approach are the use of microwave-derived soil moisture, land surface temperature and vegetation density, as well as the detailed estimation of rainfall interception loss. The modelled evaporation is validated against one year of eddy covariance measurements from 43 stations. The estimated annual totals correlate well with the stations' annual cumulative evaporation (R=0.80, N=43) and present a low average bias (−5%). The validation of the daily time series at each individual station shows good model performance in all vegetation types and climate conditions with an average correlation coefficient of R=0.83, still lower than the R=0.90 found in the validation of the monthly time series. The first global map of annual evaporation developed through this methodology is also presented.
The International Soil Moisture Network: a data hosting facility for global in situ soil moisture measurements
Authors: Dorigo W. A. , Wagner W. , Hohensinn R. , Hahn S. , Paulik C. , Drusch M. , Mecklenburg S. , van Oevelen P. , Robock A. , Jackson T.
Published: February 2011

Abstract. In situ measurements of soil moisture are invaluable for calibrating and validating land surface models and satellite-based soil moisture retrievals. In addition, long-term time series of in situ soil moisture measurements themselves can reveal trends in the water cycle related to climate or land cover change. Nevertheless, on a worldwide basis the number of meteorological networks and stations measuring soil moisture, in particular on a continuous basis, is still limited and the data they provide lack standardization of technique and protocol. To overcome many of these limitations, the International Soil Moisture Network (ISMN; http://www.ipf.tuwien.ac.at/insitu) was initiated to serve as a centralized data hosting facility where globally available in situ soil moisture measurements from operational networks and validation campaigns are collected, harmonized, and made available to users. Data collecting networks share their soil moisture datasets with the ISMN on a voluntary and no-cost basis. Incoming soil moisture data are automatically transformed into common volumetric soil moisture units and checked for outliers and implausible values. Apart from soil water measurements from different depths, important metadata and meteorological variables (e.g., precipitation and soil temperature) are stored in the database. These will assist the user in correctly interpreting the soil moisture data. The database is queried through a graphical user interface while output of data selected for download is provided according to common standards for data and metadata. Currently (status January 2011), the ISMN contains data of 16 networks and more than 500 stations located in the North America, Europe, Asia, and Australia. The time period spanned by the entire database runs from 1952 until the present, although most datasets have originated during the last decade. The database is rapidly expanding, which means that both the number of stations and the time period covered by the existing stations are still growing. Hence, it will become an increasingly important resource for validating and improving satellite-derived soil moisture products and studying climate related trends. As the ISMN is animated by the scientific community itself, we invite potential networks to enrich the collection by sharing their in situ soil moisture data.
Economic motivation of households to undertake private precautionary measures against floods
Authors: Kreibich H. , Christenberger S. , Schwarze R.
Published: February 2011

Abstract. Flood damage is on the increase due to a combination of growing vulnerability and a changing climate. This trend can be mitigated only through significantly improved flood risk management which, alongside the efforts of public authorities, will include improvements in the mitigation measures adopted by private households. Economically "reasonable" efforts to self-insure and self-protect should be expected from households before the government steps in with publicly-funded relief programmes. To gain a deeper understanding of the benefits of households' precautionary measures, telephone interviews with private home owners were conducted in the Elbe and Danube catchments in Germany after the floods of 2002 and again after the floods in 2005 and 2006. Only detached, solid single-family houses were included in this study, which is based on 759 interviews. In addition, market-based cost assessments were solicited based on a "model building". Expert interviews and a literature review – including catalogues and price lists for building materials and household appliances – were used as back-up information for the cost assessments. The comparison of costs and benefits shows that large investments, such as building a sealed cellar, are only economically efficient if the building is flooded very frequently, that is, if it is located in a high flood risk area. In such areas it would be preferable in economic terms not to build a new house at all – or else to build a house without a cellar. Small investments, however, such as oil tank protection, can prevent serious damage at low cost. Such investments are still profitable even if the building is flooded every 50 years or less on average. It could be argued that these low-cost measures should be made mandatory through the enforcement of building codes. Financial incentives built into insurance contracts coupled with limits set on governmental relief programmes would provide an economic motivation for people to invest in precautionary measures.