bluuebunny/crossref_metadata_2025 huggingface dataset:
Bits and Pieces
Authors: Eisenberg Michael , Buechley Leah , Elumeze Nwanua
Published: January 2012

The reigning portrait of mobile technology for children has, by and large, been founded on a portrait of computing derived from an earlier generation of desktop devices. That is, the recurring image of “mobile computing” employs a full-scale personal computer shrunk down to handheld size (as in a PDA or iPhone). While this image suggests avenues for innovation, it nevertheless reflects a highly constrained view of computing that fails to do justice to the educational possibilities of children’s informal day-to-day activities. This article seeks to challenge the “PDA-centric” view of children’s mobile technology by discussing two major design themes that lead in alternative directions: namely, material computing (endowing physical substrates of various kinds with computational capabilities) and piecewise computing (enhancing mobility through the dissociation of various functional capabilities of traditional computers). In discussing these themes, the authors draw on design projects.
MuseumScrabble
Authors: Sintoris Christos , Stoica Adrian , Papadimitriou Ioanna , Yiannoutsou Nikoleta , Komis Vassilis , Avouris Nikolaos
Published: January 2012

Mobile technology has created new possibilities for location-based playful learning experiences. This article describes the MuseumScrabble mobile game, aimed at children visiting a historical museum. The game requires that the players explore the museum and link abstract concepts with physical artefacts using a mobile device. The focus of this article is on the interaction design process and the subsequent observations made during field evaluation of the game. Design principles that guide the development of such a game are presented and concern playfulness, learning, social interaction, physical aspects of the game and flow between physical and digital space. This article explores how these design principles are reflected in the study and how problem-solving strategies and collaboration and competition patterns are developed by children in this multi-player educational game.
Cocktail
Authors: Yoo Jong-Woon , Hwang Woomin , Seok Hyunchul , Park Sung Kyu , Kim Chulmin , Choi Woong Ho , Park Kyu
Published: January 2012

Today’s mobile devices are capable of creating and storing a large amount of multimedia data, but sharing such data with others remains challenging. Even when a user wishes to send a picture to a friend located next to the user, current wireless data transfer techniques usually demand several steps requiring inconvenient user involvement, such as manipulation of tiny buttons on a small touch screen. This paper presents ‘Cocktail’, a new gesture-based mobile interaction system that exploits gestures employed by bartenders for easy data sharing between co-located users. In our system, users can pour (transfer) multimedia data in their mobile devices to other friends’ devices in a manner akin to a bartender pouring a drink into a glass. Cocktail also provides an intuitive way of creating new content by mixing existing data with a shaking gesture. For example, users can make music videos with their favorite music and pictures in the mobile phone by selecting them and shaking the mobile phone. The authors have implemented a prototype of Cocktail with commercial smart phones and evaluated its usability via user studies.
Channel Modeling for Vehicle-to-Vehicle Communications and Networking
Authors: Matolak David W.
Published: January 2012

This chapter provides a description of physical layer characteristics for the mobile wireless channel for vehicle-to-vehicle (V2V) communication and networking applications. Due to the low antenna elevations, and mobility of both transmitters and receivers in the V2V environment, the V2V wireless channel can be one of the most challenging elements to ensuring reliable V2V communication.
Modulation and Coding Techniques for Inter-Vehicular Communications
Authors: Sterian Corneliu Eugen D.
Published: January 2012

Direct inter-vehicular communications are presumably more difficult to perform than communications within a cellular network or between a moving vehicle and the roadside, where there is a large fixed infrastructure. It is assumed in this chapter that the mobile channel between the two vehicles is so rapidly variable that it is not possible to measure it in real-time. The authors therefore selected and considered only modulation and coding techniques for which the knowledge of the channel state was not necessary at both the transmitter and the receiver, that is, differential and noncoherent communications. To be realistic, only space-time coding communication systems with two transmit antennas were considered. The authors have purposely avoided too much theoretical development, with the intent of making clear that the implementation of all the techniques mentioned in this chapter, it should not be a too difficult task for the electronic technology of today. Future research directions are also suggested to conclude the chapter.
Channel Impairments for V2V Communications in ITS Scenarios
Authors: Muñoz D. , Rodríguez R. , Reyes S. Villarreal
Published: January 2012

This chapter describes different propagation scenarios in V2V communications based on practical Intelligent Transportation System applications. The intention is the study of propagation impairments for modeling purposes. It is important to consider the environmental characteristics of the scenario in order to choose the proper model to evaluate performance. The intention of this chapter is to explore how well current models fit the scenarios and to identify areas of opportunity for new model design. Many devices including sensors, transponders, and communication radios of different kinds co-exist in a typical urban scene. Interference among these devices and electromagnetic coupling with external waves is possible. Therefore, integration of the various technologies is imperative, and conditions for physical interaction of the radio waves needs to be provided. This is critical for the correct function of automatic systems that control safety sensible information. Very strict standard electromagnetic compatibility restrictions and regulations are applied to vehicles. These emissions and immunity tests need to be reengineered in the near future in order to consider new radio devices for communication among vehicles through sensors and transponders.
Reactive Location-Based Routing Algorithm with Cluster-Based Flooding
Authors: Santos Raul Aquino
Published: January 2012

Location-Based Routing Algorithm with Cluster-Based Flooding (LORA-CBF) employs two location services: Simple and Reactive. A Simple Location Service has been implemented for neighbors nodes, and for faraway nodes, a Reactive Location Service is employed. In LORA-CBF, the source node includes the location of its destination in each packet. The packet moves hop by hop through the network, forwarded along via cooperating intermediates nodes. At each node, a purely local decision is made to forward the packet to the neighbor that is geographically closest to the destination. However, location information by itself does not guarantee the transmission between neighboring nodes in vehicular ad-hoc networks. Mobility and contention of wireless media may cause loss of packets being transferred, and this is very important aspect to consider in the development of wireless routing algorithms. Here, the authors have addressed this problem by including a predictive algorithm in LORA-CBF.
Communication Architectures and Services for Intelligent Transport Systems
Authors: Aguado Marina , Toledo Nerea , Berbineau Marion , Jacob Eduardo
Published: January 2012

Current challenges in mobility and sustainable development are closely related to increasing travel safety, optimizing the use of transport infrastructure, reducing operating and maintenance costs and making public transport more attractive. The proposed solutions to these major challenges depend to a high extent, on political decisions, development of good practices, and also on the innovation and technology introduced through on-going Intelligent Transport Systems (ITS) programs and initiatives. This chapter provides an overview on the communication architectures able to support these ITS programs. In order to do so, this chapter presents the current standardization initiatives in the vehicular environment, a description from the telecom point of view of the different ITS services, and finally, a survey on the radio access technologies capable of dealing with such a demanding scenario.
Analyzing the Trade-Offs Between Security and Performance in VANETs
Authors: Serna Jetzabel , Luna Jesus , Morales Roberto , Medina Manel
Published: January 2012

Vehicular Ad-hoc NETworks (VANETs) currently provide a prominent field of research, which aims at improving everyday road safety and comfort. To achieve this, the deployment of several potential applications is envisioned, promising to provide extraordinary benefits, but will also represent important security challenges due to the unique characteristics of VANETs. In this chapter, VANET’s security issues are addressed, and the most outstanding security approaches are discussed. As a proof of concept, a PKI -based protocol, able to cope with the interoperability issues among untrusted CA domains is presented, and the trade-offs between security and performance are empirically analyzed and stressed.
Data Dissemination in Vehicular Networks
Authors: Maslekar Nitin , Boussedjra Mounir , Labiod Houda , Mouzna Joseph
Published: January 2012

Vehicular ad hoc networks (VANETs) represent an important component necessary to develop Intelligent Transportation Systems. Recent advances in communications systems have created significant opportunities for a wide variety of applications and services to be implement in vehicles. Most of these applications require a certain dissemination performance to work satisfactorily. Although a variety of optimizations are possible, the basic idea for any dissemination scheme is to facilitate the acquisition of the knowledge about the surrounding vehicles. However, the dynamic nature of vehicular networks makes it difficult to achieve an effective dissemination among vehicles. This chapter provides an overview on those challenges and presents various approaches to disseminate data in vehicular networks.
Toward a Unifying Framework for Defining Internal Human Resource Flexibility
Authors: Martín Inmaculada Beltrán
Published: January 2012

A flexible workforce is emerging as a critical success factor to counteract certain organizational rigidities and to guarantee organizational competitiveness in challenging environments .This chapter provides a review of the relevant definitions and classifications of human resource (HR) flexibility that have appeared during recent years. Furthermore, the chapter presents a definition of internal HR flexibility based on the resource-based view approach. From this perspective, HR flexibility is defined as a multidimensional concept. Specifically, this chapter assumes that employees are flexible when they show intrinsic flexibility (i.e. they can easily move between tasks and roles), modification flexibility (i.e. they alter their skills and/or behaviors to adapt to new circumstances), and relational flexibility (i.e. they participate in collaborative activities).
Outsourcing the HR Function in the New Economy
Authors: Valverde Mireia , Romeu Sergi , Gascó José Luís
Published: January 2012

In the current changing economic environment, organisations are searching for ever more flexibility in their quest towards competitiveness. One of the avenues towards flexibility is the outsourcing of some business processes, whether it is to achieve cost cutting or acquire expertise from external organisations. The HR function or some of its components have also been subjected to outsourcing for some time. However, the decision of what to outsource, how, when, and to whom in HR is not exempt from risks. This chapter reviews the existing literature on outsourcing the HR function that has addressed these questions and generates and agenda for research in order to orient researchers’ efforts to reach more conclusive evidence about the practice of HR outsourcing.
E-Recruitment
Authors: Holm Anna B.
Published: January 2012

E-recruitment, also known as online or Web-based recruitment, is little discussed in research from an organizational perspective. The aim of this chapter, therefore, is to analyze and discuss the process of e-recruitment, its key constituents, and organizing principles, based on the results of a qualitative study conducted in 2008-2009, together with data from industrial reports, articles from practitioner magazines, and in-depth interviews. The chapter provides a summary of e-recruitment properties and a composite matrix of the overall elements of e-recruitment organizing. E-recruitment is viewed as a case of virtual organizing, i.e. the organization of processes and activities, which, via technology and human agents, facilitate time- and space-independent interaction and collaboration. The chapter closes with a brief discussion of implications for HR managers and professionals and avenues for future research.
Strategic and Organizational Considerations Related to an E-Learning Model
Authors: Calvo Nuria , Rungo Paolo , Moreno Ignacio
Published: January 2012

The aim of this chapter is to assess the impact of different organizational factors on the success of e-learning programs, in terms of both self-reported satisfaction and the level of learning. Hence, this study adds to the analysis of the efficacy of e-learning models from an organizational perspective by providing some useful insights, which may help to improve decision-making related to employee’s continuing education and satisfaction. This simulation, using a bivariate ordered probit model, shows that economic and indirect economic incentives play a key role in augmenting the level of both satisfaction and learning. This analysis also considers how efficacy of learning programs may thus improve by linking the human resources development policy with results obtained in e-learning courses.
The Competency-Based Human Resource Management Model
Authors: Conca Jorge Valdés , de Juana-Espinosa Susana
Published: January 2012

It seems appropriate and coherent to start this study with a detailed description of the basic analysis unit in the human resource management model that constitutes the study object of this chapter: competency. With this aim in mind, the first section in this chapter is dedicated to three tasks the authors consider basic and introductory: (a) defining the concept of competency through the different approaches made by some of the most outstanding authors in this field; (b) dissecting that concept in its various elements or components so that it can be better interpreted; and finally (c) presenting a number of classifications thanks to which the treatment of certain competencies can be prioritised.
Competence-Based Profile to Characterize Successful Entrepreneurs
Authors: Canós-Darós Lourdes , Santandreu-Mascarell Cristina
Published: January 2012

In this chapter, the authors list different points of view about entrepreneurship and entrepreneurs. For this, they take into account the relationship between an entrepreneur and his or her environment. Thus, the chapter identifies the main competences that characterize an entrepreneur distinguishing between innate and/or learned competencies.
Leadership Talent Development in the New Economy
Authors: Manuel de Haro José , Carrión José Antonio
Published: January 2012

In this chapter, the authors analyze how it is possible to achieve the best results in the task of developing leaders. For this purpose, they first present as a starting point a framework based on strategic principles for managerial development which have to be assumed before taking action and, after which, they propose the operational means which allow to go beyond what has so far constituted the content of the organizational practices in this field. Intentions are as follows: reducing the level of complexity perceived about the concept itself and about its tools; including the most relevant managerial development contents; presenting an orderly, consistent process which can guide future interventions in this field. At present, and even though the authors think that the contribution made in this chapter will help introduce significant improvements in managerial development practices, there are still quite a few pending issues that will gradually have to be solved in order to make progress.
Listening and Leadership
Authors: Castaño Javier Pagán , Benítez Dolores Garzón
Published: January 2012

In this chapter, the authors will focus on three ideas: the connection between the company results and the leader’s listening skills; people as the firm’s most valuable resource; and therefore, internal communication as the key for success and full potential of the company. However, the survey concludes that internal communication is scarce and not always effective since one way communication seems to be the most common form of interaction, even though leaders know the importance and value of their human resources.
Analysis of Gender Equality in Higher Management Levels
Authors: Calvo Nuria , Bastida María , Feás Jacobo
Published: January 2012

The main goal of this chapter is to undertake a critical analysis of the current situation concerning the equal treatment of female managers in Spain. In this chapter, the authors analysed the dynamics of business behaviour in order to understand why inequality of women managers for gender reasons persists in spite of the anti-discrimination measures recommended by the legislative framework in place. This analysis has allowed proposals for measures to be drawn up to be taken into account in designing human resources strategies, based on systems of management by competencies and assessment of managerial performance.
El Dorado County Libraries in Collaboration with First 5 of El Dorado Children and Families Commission and Partnering Agencies
Authors: Brooks Carolyn
Published: January 2012

The partnerships of the El Dorado County Library system (EDC Libraries) with the First 5 El Dorado Children and Families Commission (First 5 El Dorado) and other public and private organizations have created a unique web of collaborations to enhance the pre-literacy competency and confidence of young children, newborn to five years old, and their families and caregivers in their communities. In recent years, the EDC Libraries have exponentially increased the number of library-based educational services for these young people and their families. In 2010, 43,000 young children, their parents, and caregivers participated successfully in the pre-literacy-based programs with EDC Libraries and their collaborative partners.
In Quest of Academic Achievement
Authors: Osuigwe Nkem Ekene
Published: January 2012

This chapter describes various readership promotion activities undertaken by a Nigerian State Public Library in partnership with schools, churches, and the state owned television house. Massive failures in O’ level national and regional examinations and the entrance examinations into the tertiary institutions have brought up the fact that the education sector in Nigeria is facing monumental challenges. This combined with a noticeable decline in user statistics, especially amongst school age children in Onitsha Public Library in South East Nigeria. This decline has long been associated with the school-boy drop-out syndrome. The State Public Library Board collaborated with agencies in its community to introduce intervention strategies to halt the trend. These were expected to increase usage of the public and school libraries, make reading attractive to children of school age, support school curriculum, and help students make better grades in examinations.
A New Evolution in Science Collaboration
Authors: Segraves Erica
Published: January 2012

The Mamie Doud Eisenhower Public Library is a single site, medium sized, municipal library in Broomfield, CO. After receiving an initial matched grant of $50,000 from the Sandoz US Foundation ten years ago to build the Sandoz Science and Education Center located on the first floor of the library, the continued partnership with Sandoz Pharmaceuticals, Inc. has evolved into the development of a Science Task Force composed of scientists in the community willing to volunteer their time to bring science programming to the library. This chapter details the initial development and subsequent growth of these partnerships as well as how the evolution of this collaboration has impacted the Young Adult Department science programming and education services. The chapter also focuses on developing collaborations with local companies as well as finding volunteers in the community. Procedural information regarding the recruiting and retaining of volunteers as well as key points in program planning, executing, and evaluating are also shared.
Cross – Generational Learning Case Study
Authors: Lovatt Susan
Published: January 2012

“No public library, however large and well funded, can meet all the needs of its customers on its own” (2010, IFLA, p. 28). With fewer staff resources, collaborations and partnerships have become even more important in today’s economic environment to help deliver a quality service to library customers. The working partnership established between Malahide Library and the local post-primary school delivers mutual benefits to both. It has enabled the library to meet its customers’ needs through sources of volunteers who assist in the delivery of technology-based classes within the library. The cross-generational approach of the partnership has enabled the students to fulfill their school requirements of engaging in social responsibility and developing life skills. The partnership has assisted in enhancing the role of the library within the community and fostering good relationships with its future customers.
A Tale of Two Schools
Authors: Ellis Karen
Published: January 2012

This case study illustrates two partnerships between the Taylor Public Library and two area schools, first with the Taylor Independent School District for facility use, and second with the Temple College satellite campus at Taylor for their use of the public library facilities in exchange for a free student worker. The partnership with the local school district was specifically during 2002 through 2006 to continue providing programming during the summer. The Taylor Public Library lost its old facility, and while temporarily located elsewhere, had no venue for summer programs. The library and the school district partnered to hold the summer events on local campuses until the new public library building opened in 2007. The partnership between the Taylor Public Library and Temple College consisted of use of library space to house the college’s nursing and medical collections, allow access to these holdings to enrolled college students, and grant students public library cards. For this use, the Taylor Public Library acts as supervisor for a qualifying student worker, funded by Temple College.
Key Aspects of Free and Open Source Enterprise Resource Planning Systems
Authors: Atem de Carvalho Rogerio , Johansson Björn
Published: January 2012

This chapter introduces basic differences between Free/Open Source Enterprise Resources Planning systems (FOS-ERP) and Proprietary ERP (P-ERP), revisiting the previous work of Carvalho (2008). Taking into account that some years has passed and the economic downturn came, it updates key aspects of FOS-ERP under both vendor and adopter perspectives. Like its predecessor, this chapter contributes to broaden the discussion around FOS-ERP, showing that its differences from its proprietary counterpart go beyond the cost factor.
Developing Business Model with Open Source Enterprise Resource Planning
Authors: Deodhar Swanand J. , Saxena Kulbhushan C. , Gupta Rajen K. , Ruohonen Mikko
Published: January 2012

Open source approach to software development has been used to develop the so-called ‘horizontal infrastructure’ software such as databases and application servers. However, there is an increasing acceptance of open source approach for developing business applications like enterprise resource planning (ERP) software. Indeed, organizations are building business models around ERP and similar business application developed using open source. In this chapter, the authors analyze the business model of one such open source ERP and explain increasing importance of software licensing and partner networks in FOS-ERP business models.
SMEs and FOS-ERP Systems
Authors: Stefanou Constantinos J.
Published: January 2012

Free/Open Source Enterprise Resource Planning (FOS-ERP) software is an emerging phenomenon having the potential to revolutionize the ERP market worldwide. This chapter focuses on the FOS-ERP market for Small and Medium-sized Enterprises (SMEs) and aims at informing managers, scholars, students and researchers of the opportunities and the related risks for SMEs wishing to adopt and implement a FOS-ERP solution. It is widely accepted that SMEs, which have limited capital and other resources, are among the organizations to be benefited by the existence of FOS-ERP by acquiring a system similar to that used by large enterprises. At the same time there are certain risks in adopting a FOS-ERP solution such as security issues and hidden costs. Guidelines for SMEs to eliminate these risks are provided. In order to define the backdrop of FOS-ERP systems, Web 2.0, cloud computing and Open Source Software (OSS) are also discussed.
Security Management Issues for Open Source ERP in the NGN Environment
Authors: Stojanovic Mirjana D. , Acimovic-Raspopovic Vladanka S. , Rakas Slavica Bostjancic
Published: January 2012

This chapter aims to provide a critical evaluation of security issues and potential solutions related to the use of free and open enterprise resource planning (FOS ERP) systems in highly dynamic and heterogeneous next generation networks (NGN). The authors first present a brief state of the art with respect to technologies, features and applicability of the existing security solutions for ERP systems. Second, they address security issues in FOS ERP systems. Further, they consider research directions concerning NGN infrastructure security, with a particular focus to the importance of building advanced security management systems. Properly defined service level agreement between the customer and the provider represents a starting point for provisioning of secure services with the required quality. The authors also propose policy-based security management architecture, in a wider context of quality of service management system.
The Relationship between Winter Temperature Rise and Soil Fertility properties
Authors: Guoju Xiao , Qiang Zhang , Jiangtao Bi , Fengju Zhang , Chengke Luo
Published: January 2012

The effects of winter temperature rises on soil microbial activity, nutrient and salinity in Ningxia Plain were studied in a field experiment using an infrared radiator to raise temperatures. Winter temperature rises led to increases in soil organic matter, available phosphorus, soil pH and total salt content, but decreased the available nitrogen in soil and the activities of soil catalase, urease and phosphatase. With a winter temperature of 0.5 °C-2.0 °C, the activities of soil catalase, urease and phosphatase were respectively decreased by 0.08-1.20 mL g-1, 0.004-0.019 mg g-1, and 0.10-0.25 mg kg-1; soil organic matter was increased by 0.01-0.62 g kg-1, available nitrogen decreased by 2.45-4.66 g kg-1, available phosphorus increased by 2.92-5.74 g kg-1; soil pH increased by 0.42-0.67, and total salt increased by 0.39-0.50 g kg-1. Winter temperature rises decreased soil microbial activity, accelerated the decomposition of soil nutrients, and intensified soil salinization.
Interkingdom Gene Transfer May Contribute to the Evolution of Phytopathogenicity in Botrytis Cinerea
Authors: Zhu Bo , Zhou Qing , Xie Guanlin , Zhang Guoqing , Zhang Xiaowei , Wang Yanli , Sun Gunchang , Li Bin , Jin Gulei
Published: January 2012

The ascomycete Botrytis cinerea is a phytopathogenic fungus infecting and causing significant yield losses in a number of crops. The genome of B. cinerea has been fully sequenced while the importance of horizontal gene transfer (HGT) to extend the host range in plant pathogenic fungi has been recently appreciated. However, recent data confirm that the B. cinerea fungus shares conserved virulence factors with other fungal plant pathogens with narrow host range. Therefore, interkingdom HGT may contribute to the evolution of phytopathogenicity in B. cinerea. In this study, a stringent genome comparison pipeline was used to identify potential genes that have been obtained by B. cinerea but not by other fungi through interkingdom HGT. This search led to the identification of four genes: a UDP-glucosyltransferase (UGT), a lipoprotein and two alpha/beta hydrolase fold proteins. Phylogenetic analysis of the four genes suggests that B. cinerea acquired UGT from plants and the other 3 genes from bacteria. Based on the known gene functions and literature searching, a correlation between gene acquision and the evolution of pathogenicity in B. cinerea can be postulated.
Strategic Procedures and Revisions for implementing Telemedicine and Telecare in Greece
Authors: Tsirintani M.
Published: January 2012

The development of telemedicine and telecare has been changed all over the world the recent decades as practitioners and health care managers reached better understanding of the use of information and communication technologies to offer urgent and qualified medical services at a distance. Governments and health care providers have shown a large initial interest in the benefits of telemedicine services to reduce costs mostly for patient’s transfer to tertiary hospitals or for educational purposes but have been slow to provide strategic plans and procedures in order to proceed the projects into practice.

The paper identifies the involvement of governments, healthcare management, healthcare professionals and IT suppliers in telemedicine policy development and reviews the experience of Greece in the specific field which seems that despite the enormous scientific interest for both medicine and health informatics, the practice until now has not gained the expected results. Furthermore, the analysis concerns the critical success factors that have to be revised simultaneously with the main managerial principles for the design and implementation of quality telemedicine and telecare services.
Organic matter and non-refractory aerosol over the remote Southeast Pacific: oceanic and combustion sources
Authors: Shank L. M. , Howell S. , Clarke A. D. , Freitag S. , Brekhovskikh V. , Kapustin V. , McNaughton C. , Campos T. , Wood R.
Published: January 2012

Abstract. Submicron aerosol physical and chemical properties in remote marine air were measured from aircraft over the Southeast Pacific during VOCALS-REx in 2008 and the North Pacific during IMPEX in 2006, and aboard a ship in the Equatorial Pacific in 2009. A High Resolution – Particle Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS) measured non-refractory submicron aerosol composition during all campaigns. Sulfate (SO4) and organics (Org), during VOCALS and the cruise show lower absolute values than those reported for previous "clean air" studies. In the marine boundary layer, average concentrations for SO4 were 0.52 μg m−3 for the VOCALS region and 0.85 μg m−3 for the equatorial region while average Org concentrations were 0.10 and 0.07 μg m−3, respectively. Campaign average Org/SO4 ratios were 0.19 (VOCALS) and 0.08 (equatorial Pacific). Black carbon (BC) measurements from a single particle soot photometer (SP2) and carbon monoxide (CO) concentrations over the Southeast Pacific provided sensitive indicators of pollution. CO and BC were used to identify the least polluted air, which had average concentrations of SO4 and Org of 0.14 and 0.01 μg m−3, respectively, with an average Org/SO4 of 0.08. Data from IMPEX was constrained to similar clean air criterion, and resulted in an average Org/SO4 ratio of 0.19. Under the cleanest MBL conditions during VOCALS, identified by CO below 61 ppbv, a robust linear relationship between Org and BC concentrations revealed that even at very low pollution levels, combustion sources dominated organic aerosol, suggesting little to no marine source of submicrometer Org to the atmosphere over the eastern South Pacific. This means marine organics cannot be identified by merely setting a standard for background conditions below which anthropogenic influence can be disregarded. Other methods must be used to exclude non-marine sources.
The summer aerosol in the Central Arctic 1991–2008: did it change or not?
Authors: Heintzenberg J. , Leck C.
Published: January 2012

Abstract. In the course of global warming dramatic changes are taking place in the Arctic and boreal environments. However, physical aerosol data in from the central summer Arctic taken over the course of 17 years from 1991 to 2008 to not show clear trends, albeit substantial interannual variations. Several causes can be responsible for these findings. The processes controlling concentrations and particle size distribution of the aerosol over the central Arctic perennial pack ice area, north of 80, may not have changed substantially during this time. Environmental changes are still mainly effective in the marginal ice zone, the ice-free waters and continental rims and have not propagated significantly into the central Arctic yet where they could affect the local aerosol and its sources. The analysis of meteorological conditions of the four expedition summers reveal substantial variations which we see as main causes of the measured variations in aerosol parameters and the lack of clear decadal trends. With combined lognormal fits of the hourly number size distributions of the four expeditions representative mode parameters for the summer aerosol in the central Arctic have been calculated. The combined aerosol statistics discussed in the present paper provide comprehensive physical data on the summer aerosol in the central Arctic. These data are the only aerosol information from this region and will probably remain so for some time because orbiting satellites do not cover the area close to the North Pole.
Seasonal variations of water-soluble organic carbon, dicarboxylic acids, ketoacids, and α-dicarbonyls in the central Himalayan aerosols
Authors: Hegde P. , Kawamura K.
Published: January 2012

Abstract. Aerosol samples were collected from a high elevation mountain site (Nainital, India; 1958 m a.s.l.) in the central Himalayas, which provide an isolated platform above the planetary boundary layer to better understand the composition of the remote continental troposphere. The samples were analyzed for water-soluble dicarboxylic acids (C2–C12) and related compounds (ketocarboxylic acids and α-dicarbonyls), as well as organic carbon, elemental carbon and water soluble organic carbon. The contributions of total dicarboxylic acids to total aerosol carbon during wintertime were 1.7 and 1.8%, for day and night, respectively whereas they significantly reduced during summer. Molecular distributions of diacids demonstrated that oxalic (C2) acid was the most abundant species followed by C4 and C3 diacids. The average concentrations of total diacids (433 ± 108 ng m−3), ketoacids (48 ± 23 ng m−3), and α-dicarbonyls (9 ± 4 ng m−3) were similar to those from Asian cities such as Tokyo, Beijing and Hong Kong. During summer season most of the organic species were several times more abundant than in winter. Phthalic acid, which originates from oxidation of polycyclic aromatic hydrocarbons such as naphthalene, was found to be 7 times higher in summer than winter. This feature has not been reported in atmospheric aerosols. Based on molecular distributions and air mass backward trajectories, we report that dicarboxylic acids and related compounds in Himalayan aerosols are influenced by the anthropogenic activities from highly populated Indo-Gangetic plain areas.
The ACOS CO2 retrieval algorithm – Part 1: Description and validation against synthetic observations
Authors: O'Dell C. W. , Connor B. , Bösch H. , O'Brien D. , Frankenberg C. , Castano R. , Christi M. , Eldering D. , Fisher B. , Gunson M. , McDuffie J. , Miller C. E. , Natraj V. , Oyafuso F. , Polonsky I. , Smyth M. , Taylor T. , Toon G. C. , Wennberg P. O. , Wunch D.
Published: January 2012

Abstract. This work describes the NASA Atmospheric CO2 Observations from Space (ACOS) XCO2 retrieval algorithm, and its performance on highly realistic, simulated observations. These tests, restricted to observations over land, are used to evaluate retrieval errors in the face of realistic clouds and aerosols, polarized non-Lambertian surfaces, imperfect meteorology, and uncorrelated instrument noise. We find that post-retrieval filters are essential to eliminate the poorest retrievals, which arise primarily due to imperfect cloud screening. The remaining retrievals have RMS errors of approximately 1 ppm. Modeled instrument noise, based on the Greenhouse Gases Observing SATellite (GOSAT) in-flight performance, accounts for less than half the total error in these retrievals. A small fraction of unfiltered clouds, particularly thin cirrus, lead to a small positive bias of ~0.3 ppm. Overall, systematic errors due to imperfect characterization of clouds and aerosols dominate the error budget, while errors due to other simplifying assumptions, in particular those related to the prior meteorological fields, appear small.
Atmospheric effect on the ground-based measurements of broadband surface albedo
Authors: Manninen T. , Riihelä A. , de Leeuw G.
Published: January 2012

Abstract. Ground-based pyranometer measurements of broadband surface albedo values are affected by the atmospheric conditions. A new method for estimating the magnitude of this effect in clear sky conditions is presented. Global and reflected radiation values and AOD values at two wavelengths are needed to apply the method. Depending on the atmospheric optical depth and the sun zenith angle values the effect can be as large as 20%. For the test case of Cabauw the atmosphere caused typically 5% higher surface albedo values than the corresponding black-sky surface albedo values.
Possible source of ancient carbon in phytolith concentrates from harvested grasses
Authors: Santos G. M. , Alexandre A. , Southon J. R. , Treseder K. K. , Corbineau R. , Reyerson P. E.
Published: January 2012

Abstract. Plants absorb and transport silicon (Si) from soil, and precipitation of Si within the living plants results in micrometric amorphous biosilica particles known as phytoliths. During phytolith formation, a small amount of carbon (< 2 %) can become occluded in the silica structure (phytC) and therefore protected from degradation by the environment after plant tissue decomposition. Since the major C source within plants is from atmospheric carbon dioxide (CO2) via photosynthesis, the current understanding is that the radiocarbon (14C) content of phytC should reflect the 14C content of atmospheric CO2 at the time the plant is growing. This assumption was recently challenged by 14C data from phytoliths extracted from living grasses that yielded ages of several thousand years (2–8 kyr BP; in radiocarbon years "Before Present" (BP), "Present" being defined as 1950). Because plants can take up small amounts of C of varying ages from soils (e.g. during nutrient acquisition), we hypothesized that this transported C within the plant tissue could be attached to or even embedded in phytoliths. In this work, we explore this hypothesis by reviewing previously published data on biosilica mineralization and plant nutrient acquisition as well as by evaluating the efficiency of phytolith extraction protocols from Scanning Electron Microscope (SEM) images and Energy Dispersive Spectrometer (EDS) analyses from harvested grasses phytolith concentrates. We show that current extraction protocols are inefficient since they do not entirely remove recalcitrant forms of C from plant tissue. Consequently, material previously measured as "phytC" may contain at least some fraction of soil-derived C (likely radiocarbon-old) taken up by roots. We also suggest a novel interpretation for at least some of the phytC – enters via the root pathway during nutrient acquisition – that may help to explain the old ages previously obtained from phytolith concentrates.
Root biomass responses to elevated CO2 limit soil C sequestration in managed grasslands
Authors: Sillen W. M. A. , Dieleman W. I. J.
Published: January 2012

Abstract. Elevated atmospheric CO2 levels and increasing nitrogen deposition both stimulate plant production in terrestrial ecosystems. Moreover, nitrogen deposition could alleviate an increasing nitrogen limitation experienced by plants exposed to elevated CO2 concentrations. However, an increased rate of C flux through the soil compartment as a consequence of elevated CO2 concentrations has been suggested to limit C sequestration in terrestrial ecosystems, questioning the potential for terrestrial C uptake to mitigate the increasing atmospheric CO2 concentrations. Our study used data from 69 published studies to investigate whether CO2 elevation and/or nitrogen fertilization could induce an increased carbon storage in grasslands, and considered the influence of management practices involving biomass removal or irrigation on the elevated CO2 effects. Our results confirmed a positive effect of elevated CO2 levels and nitrogen fertilization on plant growth, but revealed that N availability is essential for the increased C influx under elevated CO2 to propagate into belowground C pools. However, moderate nutrient additions also promoted decomposition processes in elevated CO2, reducing the potential for increased soil C storage. An important role in the soil carbon response to elevated CO2 was attributed to the root response, since there was a lower potential for increases in soil C content when root biomass was more responsive to CO2 elevation. Future elevated CO2 concentrations and increasing N deposition might thus increase C storage in plant biomass, but the potential for increased soil C storage is limited.
Use of agricultural statistics to verify the interannual variability in land surface models: a case study over France with ISBA-A-gs
Authors: Calvet J.-C. , Lafont S. , Cloppet E. , Souverain F. , Badeau V. , Le Bas C.
Published: January 2012

Abstract. In order to verify the interannual variability of the above-ground biomass of herbaceous vegetation simulated by the ISBA-A-gs land surface model, within the SURFEX modelling platform, French agricultural statistics for C3 crops and grasslands were compared with the simulations for the 1994–2008 period. While excellent correlations are obtained for grasslands, representing the interannual variability of crops is more difficult. It is shown that, the Maximum Available soil Water Capacity (MaxAWC) has a large influence on the correlation between the model and the agricultural statistics. In particular, high values of MaxAWC tend to reduce the impact of the climate interannual variability on the simulated biomass. Also, high values of MaxAWC allow the simulation of a negative trend in biomass production, in relation to a marked warming trend, of about 0.12 Kyr−1 on average, affecting the daily maximum air temperature during the growing period (April–June). This trend is particularly acute in Northern France. The estimates of MaxAWC for C3 crops and grasslands, currently used in SURFEX, are about 129 mm and do not vary much. Therefore, more accurate grid-cell values of this parameter are needed.
Soil-water dynamics and unsaturated storage during snowmelt following wildfire
Authors: Ebel B. A. , Hinckley E. S. , Martin D. A.
Published: January 2012

Abstract. Many forested watersheds with a substantial fraction of precipitation delivered as snow have the potential for landscape disturbance by wildfire. Little is known about the immediate effects of wildfire on snowmelt and near-surface hydrologic responses, including soil-water storage. Montane systems at the rain-snow transition have soil-water dynamics that are further complicated during the snowmelt period by strong aspect controls on snowmelt and soil thawing. Here we present data and analysis from field measurements of snow hydrology and subsurface hydrologic and temperature responses during the first winter and spring after the September 2010 Fourmile Canyon Fire in Colorado, USA. Our observations of soil-water content and soil temperature show sharp contrasts in hydrologic and thermal conditions between north- and south-facing slopes. South-facing burned soils were ~1–2 °C warmer on average than north-facing burned soils and ~1.5 °C warmer than south-facing unburned soils, which affected soil thawing during the snowmelt period. Soil-water dynamics also differed by aspect: in response to soil thawing, soil-water content increased approximately one month earlier on south-facing burned slopes than on north-facing burned slopes. While aspect and wildfire affect soil-water dynamics during snowmelt, soil-water storage at the end of the snowmelt period reached the value at field capacity for each plot, suggesting that post-snowmelt unsaturated storage was not substantially influenced by aspect in wildfire-affected areas. Our data and analysis indicate that snowmelt-driven groundwater recharge may be larger in wildfire-impacted areas, especially on south-facing slopes, because of earlier soil thaw and longer durations of soil-water contents above field capacity in those areas.
Climatic and geologic controls on suspended sediment flux in the Sutlej River Valley, western Himalaya
Authors: Wulf H. , Bookhagen B. , Scherler D.
Published: January 2012

Abstract. The sediment flux through Himalayan rivers directly impacts water quality and is important for sustaining agriculture as well as maintaining drinking-water and hydropower generation. Despite the recent increase in demand for these resources, little is known about the triggers and sources of extreme sediment flux events, which lower water quality and account for extensive hydropower reservoir filling and turbine abrasion. Here, we present a comprehensive analysis of the spatiotemporal trends in suspended sediment flux based on daily data during the past decade (2001–2009) from four sites along the Sutlej River and from four of its main tributaries. In conjunction with satellite data depicting rainfall and snow cover, air temperature, earthquake records, and Schmidt hammer rock strength measurements, we infer climatic and geologic controls of peak suspended sediment concentration (SSC) events. Our study identifies three key findings: First, peak SSC events (≥99th SSC percentile) coincide frequently (57–80%) with heavy rainstorms and account for about 30% of the suspended sediment flux in the semi-arid to arid interior of the orogen. Second, we observe an increase of suspended sediment flux from the Tibetan Plateau to the Himalayan front at mean annual timescales. This sediment-flux gradient suggests that averaged, modern erosion in the western Himalaya is most pronounced at frontal regions, which are characterized by high monsoonal rainfall and thick soil cover. Third, in seven of eight catchments we find an anticlockwise hysteresis loop of annual sediment flux, which appears to be related to enhanced glacial sediment evacuation during late summer. Our analysis emphasizes the importance of unconsolidated sediments in the high-elevation sector that can easily be mobilized by hydrometeorological events and higher glacial-meltwater contributions.