bluuebunny/crossref_metadata_2025 huggingface dataset:
Blind channel estimation based on maximizing the eigenvalue spread of cumulant matrices in (2 × 1) Alamouti's coding schemes
Authors: Dapena Adriana , Pérez‐Iglesias Héctor J. , Zarzoso Vicente
Published: October 2010

The popular Alamouti orthogonal space time code attains full transmit diversity in multiple antenna systems. This paper addresses the problem of blind channel identification in (2 × 1) Alamouti coded systems. Under the assumption of independent symbol substreams, the channel can be estimated from the eigendecomposition of matrices composed of second‐ or higher‐order statistics (cumulants) of the received signal. The so‐called joint approximate diagonalization of eigenmatrices (JADE) method for blind source separationviaindependent component analysis is optimal in that it tries to simultaneously diagonalize a full set of fourth‐order cumulant matrices. To reduce computational complexity, we perform the eigenvalue decomposition of a single cumulant matrix, which is judiciously chosen by maximizing its expected eigenvalue spread. Simulation results show that the resulting technique outperforms existing blind Alamouti channel estimation methods and achieves a performance close to JADE's at a fraction of the computational cost. Copyright © 2010 John Wiley & Sons, Ltd.
Analysis of thin intermediate layers by confocal µ‐XRF
Authors: Perez Roberto D. , Sánchez Héctor J. , Rubio Marcelo , Perez Carlos A.
Published: October 2010

Recently, the capabilities of the micro‐X‐ray fluorescence spectroscopy (µ‐XRF) were expanded by means of a confocal geometry. It consists of X‐ray lenses in the excitation as well as in the detection channel which defines a small probing volume. By moving an intermediate thin homogenous layer in the normal direction through this probing volume, information concerning the thickness and elemental composition can be obtained. For multilayer samples the order of the layers in the stratified structure can be obtained. In this work, we apply a new quantification algorithm for confocal µ‐XRF which can be useful in surface analysis. It is an iterative procedure valid for thin intermediate layers where the exponential attenuation of the X‐ray beams cannot be approximated. The analytical expressions involved in the proposed quantification algorithm for confocal µ‐XRF were adapted from those used for quantification of intermediate thin layers by means of conventional XRF. In this way, some of the analytical processes applied in conventional XRF can be adapted to confocal µ‐XRF. The new algorithm was applied to analyze by confocal µ‐XRF a sample of a paint layer on a glass substrate. To test the precision of the proposed algorithm, the present results were compared with conventional XRF analysis. Copyright © 2010 John Wiley & Sons, Ltd.
Mesopores in USY Zeolites
Authors: Lutz Wolfgang , Enke Dirk , Einicke Wolf‐Dieter , Täschner Dirk , Kurzhals Rolf
Published: October 2010

Zeolites of type NaY synthesised by use of seed‐solution and zeolite X‐seeds to initialise the crystallisation were compared. A different homogeneity of the internal framework structure related to the Si/Al ratio was expected. Thus, the formation of closed bulk mesopores should be influenced during treatment of NH4NaY modification for 7 hours at 450 °C and 600 °C, respectively, in the water steam of 1 bar. Occurrence of different mesopores was actually observed in obtained ultra‐stable USY zeolites using nitrogen adsorption. Whereas USY prepared by use of seed‐solution contains only open mesopores at the crystal surface, the X‐seed synthesised material contains open and closed mesopores at the surface and in the nuclei of samples, respectively.
Conductance of Graphene Nanoribbon Junctions and the Tight Binding Model
Authors: Wu Y , Childs PA
Published: October 2010

Planar carbon-based electronic devices, including metal/semiconductor junctions, transistors and interconnects, can now be formed from patterned sheets of graphene. Most simulations of charge transport within graphene-based electronic devices assume an energy band structure based on a nearest-neighbour tight binding analysis. In this paper, the energy band structure and conductance of graphene nanoribbons and metal/semiconductor junctions are obtained using a third nearest-neighbour tight binding analysis in conjunction with an efficient nonequilibrium Green's function formalism. We find significant differences in both the energy band structure and conductance obtained with the two approximations.
n-Type Doping of Vapor–Liquid–Solid Grown GaAs Nanowires
Authors: Gutsche Christoph , Lysov Andrey , Regolin Ingo , Blekker Kai , Prost Werner , Tegude Franz-Josef
Published: October 2010

In this letter, n-type doping of GaAs nanowires grown by metal–organic vapor phase epitaxy in the vapor–liquid–solid growth mode on (111)B GaAs substrates is reported. A low growth temperature of 400°C is adjusted in order to exclude shell growth. The impact of doping precursors on the morphology of GaAs nanowires was investigated. Tetraethyl tin as doping precursor enables heavily n-type doped GaAs nanowires in a relatively small process window while no doping effect could be found for ditertiarybutylsilane. Electrical measurements carried out on single nanowires reveal an axially non-uniform doping profile. Within a number of wires from the same run, the donor concentrations N
D of GaAs nanowires are found to vary from 7 × 1017 cm-3 to 2 × 1018 cm-3. The n-type conductivity is proven by the transfer characteristics of fabricated nanowire metal–insulator-semiconductor field-effect transistor devices.
A UPnP extension for enabling user authentication and authorization in pervasive systems
Authors: Sales Thiago , Sales Leandro , Almeida Hyggo , Perkusich Angelo
Published: October 2010

The Universal Plug and Play (UPnP) specification defines a set of protocols for promoting pervasive network connectivity of computers and intelligent devices or appliances. Nowadays, the UPnP technology is becoming popular due to its robustness to connect devices and the large number of developed applications. One of the major drawbacks of UPnP is the lack of user authentication and authorization mechanisms. Thus, control points, those devices acting as clients on behalf of a user, and UPnP devices cannot communicate based on user information. This paper introduces an extension of the UPnP specification called UPnP-UP, which allows user authentication and authorization mechanisms for UPnP devices and applications. These mechanisms provide the basis to develop customized and secure UPnP pervasive services, maintaining backward compatibility with previous versions of UPnP.
The Logic of Qualitative Comparative Analysis
Authors: Ragin Charles C.
Published: October 2010

Social scientists often face a fundamental dilemma when they conduct social research. On the one hand, they may emphasize the complexity of social phenomena – a common strategy in ethnographic, historical and macro social research – and offer in–depth case studies sensitive to the specificity of the things they study. On the other hand, they may make broad, homo genizing assumptions about cases, and document generalities – patterns hold across many instances. Research strategies that focus on complexity are often labeled “qualitative”, “case–oriented”, “small–N”, or “intensive”. Those that focus on generality are often labeled “quantitative”, “variable–oriented”, “large–N”, or “extensive”. While the contrasts between these two types social research are substantial, it is easy to exaggerate their differences and t o caricature the two approaches, for example, portraying quantitative work on general patterns as scientific but sterile and oppressive, and qualitative research on small Ns as rich and emancipatory but journalistic. It is important to avoid these caricatures because the contrasts between these two general approaches provide important leads both for finding a middle path between them and for resolving basic methodological issues in social science Social scientists who study cases in an in–depth manner often see empiri cal generalizations simply as a means to another end – the interpretive understanding of cases. In this view, a fundamental goal of social science is t o interpret significant features of the social world and thereby advance our collective understanding of how existing social arrangements came about and why we live the way we do. The rough general patterns that social scientists may be able to identify simply aid the understanding of specific cases; they are not viewed as predictive. Besides, the task of interpreting and then representing socially significant phenomena (or the task of making selected social phenomena significant by representing them) is a much more immediate and tangible goal. In this view, empirical generalizations and social science theory are important – to the extent that they aid the goal interpretive understanding.
Historical Inference and Event-Structure Analysis
Authors: Griffin Larry J. , Korstad Robert R.
Published: October 2010

Event-structure analysis (ESA) is a member of a family of formal analytic procedures designed to analyze and interpret text, in particular the temporal sequences constituting the narrative of a historical event. Its basic purpose is to aid the analyst in “unpacking” an event – that is, in breaking it into constituent parts – and analytically reconstituting it as a causal interpretation of what happened and why it happened as it did. ESA focuses on and exploits an event's “narrativity” – its temporal orderliness, connectedness and unfolding – thereby helping historians and social scientists infer causal links between actions in an event, identify its contingencies and follow their consequences, and explore its myriad sequential patterns. Unlike most other formal analytical techniques, it is completely non-numeric and non-statistical: ESA's value is largely heuristic and centered on how it relentlessly probes the analyst's construction, comprehension and interpretation of the event.
Competing Inequalities: The Struggle Over Reserved Legislative Seats for Women in India
Authors: Jenkins Laura Dudley
Published: October 2010

Introduction of the Women's Reservation Bill was stalled in Lok Sabha on Monday amid unprecedented scenes of snatching of papers from the Speaker and the law minister and the virtual coming to blows of members […]. As the shell shocked minister stood rooted to the spot, the member tore the papers with relish and flung them in the air provoking members from the treasury benches to storm the well. By this time, the well of the Lok Sabha looked like a veritable battle field with members from both sides preparing for a scuffle as the Speaker adjourned the House for the day.
“Blood Is a Very Special Juice”: Racialized Bodies and Citizenship in Twentieth-Century Germany
Authors: El Tayeb Fatima
Published: October 2010

The 1999 plan of the Social Democratic government to adjust Germany's 1913 nationality law has generated an intensely emotional debate. In an unprecedented action, the opposition Christian Democrats managed to gather hundreds of thousands of signatures against the adjustment that would have granted citizenship to second generation “immigrants” born in Germany. At the end of the twentieth century, Germans still strongly cling to the principle ofjus sanguinis. The idea that nationality is not connected ot place of birth or culture but rather to a “national essence” tJiat is somehow incorporated in the subject's blood has been strong in Germany since the early nineteenth century and has been especially decisive for the country's twentieth-century history.
Household Strategies for Survival: An Introduction
Authors: Fontaine Laurence , Schlumbohm Jürgen
Published: October 2010

In early modern Europe, as in developing countries today, much of the population had to struggle to survive. Estimates for many parts of pre-industrial Europe, as for several countries in the so-called Third World, suggest that the majority of the inhabitants owned so little property that their livelihood was highly insecure. Basically, all those who lived by the work of their hands were at risk, and the reasons for their vulnerability were manifold. Economic cycles and seasonal fluctuations jeopardized the livelihood of the rural and urban masses. Warfare, taxation, and other decisions by the ruling elites sometimes had far-reaching direct and indirect repercussions on the lives of the poor. This is also true of natural factors, both catastrophes and the usual weather fluctuations, which were a major factor affecting harvest yields. Equal in importance were the risks and uncertainties inherent in life and family cycles: disease, old age, widowhood, or having many young children.
Negotiating a Living: Essex Pauper Letters from London, 1800–1834
Authors: Sokoll Thomas
Published: October 2010

Research undertaken over the last generation has greatly enhanced our understanding of the survival strategies of the labouring poor in early modern Europe. Under economic conditions where poverty was endemic, most families were forced to take to various forms of work and to draw on whatever forms of income were available. Whether among small peasants, proto-industrial producers, landless labourers or casual workers, their mere subsistence depended on the effort of as many family members as possible. Women's and children's work were the norm well into the nineteenth century, and their contribution to the family income greater than previously assumed. There were, nevertheless, many who could not make ends meet. The reasons for which people had to turn to others for help are legion: structural, cyclical or seasonal unemployment and underemployment; insufficient earnings and debts; illness and accidents; death within the family. A lot of assistance was informal and went through networks of kinship, neighbourhood and local community. Friendly societies provided rudimentary forms of collectively-organized support. Some state or municipal agencies supplying poor relief and charitable institutions offered assistance of various types, but most of it was meagre and combined with social control of the clients. It is no wonder, therefore, that many people took to begging, prostitution or petty crime.
Individualization Strategies Among City Dwellers in Contemporary Africa: Balancing the Shortcomings of Community Solidarity and the Individualism of the Struggle for Survival
Authors: Marie Alain
Published: October 2010

In urban Africa today, like elsewhere, the purported survival strategies of individuals are determined constantly by severe material constraints. The poor and the new poor are overwhelmingly new city dwellers dependent on precarious, intermittent odd jobs (petits boulots; single women with small children; young school dropouts (déscolarisés, condemned to the expediencies of the streets, illicit actions and, in many cases, delinquency; unemployed graduates (diplomés-chômeurs), without opportunities for paid employment; as well as those designated successively in the vernacular as conjoncturés, déflatés and compressés (i.e. affected by wage reductions, permanent employees downgraded to temporary contracts or casual labour, and workers who have lost their jobs through massive redundancies). These individuals can meet only the most basic needs (eating, feeding their children, paying the rent). When survival becomes an issue, long-term strategies tend to be constrained by the need to fulfil the most basic needs and daily necessities. At any rate, pursuit of this objective does not involve selective mobilization of optimized means, when those who admittedly are looking out for themselves (se cherchent), rummage about (grouillent à droite [et] à gauche), pursue small jobs in unskilled manual labour or portering, or as night watchmen (racolage pour trouver des petits contrats de manoeuvrage, de manutention ou de veilleur de nuit), search constantly for opportunities to sell items that they bought for a little bit less, inland or across the border. They may also try to establish a business or small craft shop and, during the interim, get by with difficulty thanks to sporadic aid from relatives who are also unemployed.
Finding the Right Balance: Financial Self-Help Organizations as Sources of Security and Insecurity in Urban Indonesia
Authors: Lont Hotze
Published: October 2010

Financial self-help organizations can be found in many parts of the world, and the cities of Java are among the areas where they are particularly widespread. Since about the 1950s, interest in these institutions among anthropologists and development sociologists has increased considerably. Analyses of financial self-help organizations have most often focused on their economic or their social function; few scholars have pointed to their function as providers of security and identified self-help organizations as typical forms of local social security institutions. The main shortcoming of most of these studies is that they base their conclusions solely on an analysis of the financial arrangements provided by these self-help organizations, neglecting the accommodating practices that people undertake in order to fit the provisions of self-help organizations to their own household needs. This essay explores the observation that financial self-help organizations do not simply provide security through the different kinds of insurance mechanisms they might contain, but that, particularly through the way in which people use them and participate in them, these institutions become meaningful for coping with insecurity. It examines the question of whether participation in financial self-help organizations contributes to the ability of households to cope with adversities and deficiencies in a concrete social context. Research aiming to answer this question was conducted in Bujung, an urban ward on the outskirts of Yogyakarta, on the island of Java.
Stepping on Two Boats: Urban Strategies of Chinese Peasants and Their Children
Authors: Wang Danyu
Published: October 2010

During the 1990s, over seventy per cent of the married men and adult children of Stone Mill village in northeastern China have been employed i n wage labor each year. Because a vast number of household laborers (i.e. husbands, sons, and daughters) have nonagricultural jobs outside the village, daily agricultural tasks are performed by married women and elderly men, who are fondly described by the villagers of Stone Mill as “Troop Number 3860” (3860 budut). The number 38 refers to International Women's Day, March 8, representing the women in the village's agricultural labor force, while the number 60 represents the minimum age of the elderly agricultural workers.
The regulation of diplomatic practice: the beginnings to the Vienna Convention on Diplomatic Relations, 1961
Authors: Langhorne Richard
Published: October 2010

Diplomats, whose historical reputation in earlier times has so often been unsavoury, have more recently been highly regarded, except perhaps in the immediate aftermath of the First World War, for which catastrophe they were held by some to be to blame. The privations of the Cold War and the occasional severe maltreatments endured in unsettled states have from time to time since 1945 made them heroes. The change of status has, particularly since the nineteenth century, been associated with a rising sense of belonging to a recognizable and separate profession, with its own body of knowledge and skill, for which suitable candidates could be trained. This development was slow in gestation and its first signs cannot be reliably identified until the seventeenth century with the appearance of the first clutch of semi-professional manuals. From that time, a potential semantic confusion has existed arising out of the use of the adjective ‘diplomatic’ sometimes to describe the process of international political argument and its eventual success or failure in reaching agreement, and sometimes to describe the administrative mechanism of diplomacy itself. it was this latter aspect of diplomacy, seen separately from the content of policy, which from the mid nineteenth century began to attract a new kind of attention, driven particularly by international lawyers, to the point where it was beginning to seem desirable to attain a general international agreement as to what were the rules of the game.
Western intelligence, the Soviet threat and NSC-68: a reply to Beatrice Heuser
Authors: Cox Michael
Published: October 2010

In her article on the early history of the Cold War, Beatrice Heuser throws out at a challenge to those of us who have, over the past few years, cast doubt upon the idea that the USSR represented a serious military threat to the West after the Second World War. Basing her argument upon ‘American intelligence estimates’ as well as other sources, she attempts to show that Western policy-makers, hither to much criticized by many academic analysts for having exaggerated Soviet capabilities and over-dramatizing its intentions, had good reason to be fearful of the Soviet Union. ‘American and British governments’, according to Dr Heuser, ‘had information which led them to fear Soviet aggression in Europe and elsewhere’ after 1948. In the light of this information—not to mention the North Korean attack upon the South—rearmament, she argues, ‘may well have been an appropriate response to the Soviet threat’. It certainly ‘worried Stalin’ and possibly prevented Soviet aggression in Europe. It was, in short, a reasonable response to a real problem and probably contributed (although by how much can never be known) to the successful containment of the USSR. NSC-68 may not have been such a flawed document after all.
Multilateralism and world order
Authors: Cox Robert W.
Published: October 2010

‘World order’ has become a current catchphrase of political discourse and journalism. ‘Multilateralism’ has become something of a growth sector in academic studies. What current events have brought into prominence, scholarship has an obligation to subject to critical analysis. This article raises some of the questions that should be probed in this analysis.
Models of international organization in perpetual peace projects
Authors: Archibugi Daniele
Published: October 2010

Perpetual peace projects constitute a largely undervalued intellectual tradition that has attracted many polemical arrows. One of the most frequent criticisms levelled at the projects is that their authors too often abandon themselves to utopianism. Yet this tradition has proved to be much more influential than is generally recognized: contemporary international organizations, from the League of Nations to the United Nations, from the European Parliament to the International Court of Justice, were sketched out, if only in embryonic form, in these perpetual peace projects. Yet it is rare to find their authors numbered among the founders of internationalist theory.
Hirohito, the Emperor's Army and Pearl Harbor
Authors: Dockrill Saki
Published: October 2010

The death of Hirohito on 7 January 1989 provided the Japanese with an opportunity of reappraising the Showa era, as Hirohito's reign is called in the Japanese calendar. This lasted for sixty-two years, which the press described as years of ‘turmoil and drastic changes.’ While the role of the Emperor and, to a greater degree, the role of the military in imperial Japan have been long-running themes for historians, intellectuals, and journalists, Hirohito's death certainly encouraged the publication of a large number of books, including reprints of works about the Pacific War, from semi-official histories, the memoirs of some of the leading decision makers and a series of histories of Japan from 1868 to 1945. Television programmes showed for two full days panel discussions by historians and documentary films of the Showa era—a series of bloody wars in China and eventually with the Americans, the British and the other Allied powers, leading to unconditional surrender and occupation.
Information retrieval for health technology assessment: Standardization of search methods
Authors: Ormstad Sari Susanna , Isojärvi Jaana
Published: October 2010

In the theme section on information retrieval for health technology assessment (HTA), we are pleased to present a series of high-quality articles. The articles address various approaches to HTA searching and information management. Information retrieval and management is an integral part of the HTA review process. Those conducting searches must, therefore, understand the nature of the different domains of HTA, know what kind of information is needed for each domain, and know how to find it. These articles describe developments in HTA searching and other information-related activities.
Perceptions and attitudes of hospital staff toward paging system and the use of mobile phones
Authors: Haroon Muhammad , Yasin Faiza , Eckel Rachael , Walker Frank
Published: October 2010

Objectives:Our objective was to document the pattern of mobile phone usage by medical staff in a hospital setting, and to explore any perceived benefits (such as improved communications) associated with mobile phones.

Methods:This cross-sectional survey was conducted in Waterford Regional Hospital, Ireland, where bleep is the official system of communication. All non-consultant hospital doctors, of medical disciplines only, were asked to participate. The questionnaire was designed to explore the pattern and different aspects of mobile phone usage.

Results:At the time of study, there were sixty medical junior doctors, and the response rate was 100 percent. All participants used mobile phones while at work, and also for hospital-related work. For 98.3 percent the mobile phone was their main mode of communication while in the hospital. Sixty-two percent (n= 37) made 6–10 calls daily purely for work-related business, and this comprised of ≥80 percent of their daily usage of mobile phones. For 98 percent of participants, most phone calls were work-related. Regarding reasons for using mobile phones, all reported that using mobile phone is quicker for communication.

Conclusions:Mobile phone usage is very common among the medical personnel, and this is regarded as a more efficient means of communication for mobile staff than the hospital paging system.
Implanting inequality: Empirical evidence of social and ethical risks of implantable radio-frequency identification (RFID) devices
Authors: Monahan Torin , Fisher Jill A.
Published: October 2010

Objectives: The aim of this study was to assess empirically the social and ethical risks associated with implantable radio-frequency identification (RFID) devices.

Methods: Qualitative research included observational studies in twenty-three U.S. hospitals that have implemented new patient identification systems and eighty semi-structured interviews about the social and ethical implications of new patient identification systems, including RFID implants.

Results: The study identified three primary social and ethical risks associated with RFID implants: (i) unfair prioritization of patients based on their participation in the system, (ii) diminished trust of patients by care providers, and (iii) endangerment of patients who misunderstand the capabilities of the systems.

Conclusions: RFID implants may aggravate inequalities in access to care without any clear health benefits. This research underscores the importance of critically evaluating new healthcare technologies from the perspective of both normative ethics and empirical ethics.
Consumption of whole grains is associated with improved diet quality and nutrient intake in children and adolescents: the National Health and Nutrition Examination Survey 1999–2004
Authors: O’Neil Carol E , Nicklas Theresa A , Zanovec Michael , Cho Susan S , Kleinman Ronald
Published: October 2010

Objective

To examine the association of consumption of whole grains (WG) with diet quality and nutrient intake in children and adolescents.

Design

Secondary analysis of cross-sectional data.

Setting

The 1999–2004 National Health and Nutrition Examination Survey.

Subjects

Children aged 2–5 years (n2278) and 6–12 years (n3868) and adolescents aged 13–18 years (n4931). The participants were divided into four WG consumption groups: ≥0 to <0·6, ≥0·6 to <1·5, ≥1·5 to <3·0 and ≥3·0 servings/d. Nutrient intake and diet quality, using the Healthy Eating Index (HEI)-2005, were determined for each group from a single 24 h dietary recall.

Results

The mean number of servings of WG consumed was 0·45, 0·59 and 0·63 for children/adolescents at the age of 2–5, 6–12 and 13–18 years, respectively. In all groups, HEI and intakes of energy, fibre, vitamin B6, folate, magnesium, phosphorus and iron were significantly higher in those consuming ≥3·0 servings of WG/d; intakes of protein, total fat, SFA and MUFA and cholesterol levels were lower. Intakes of PUFA (6–12 years), vitamins B1(2–5 and 13–18 years), B2(13–18 years), A (2–5 and 13–18 years) and E (13–18 years) were higher in those groups consuming ≥3·0 servings of WG/d; intakes of added sugars (2–5 years), vitamin C (2–5 and 6–12 years), potassium and sodium (6–12 years) were lower.

Conclusions

Overall consumption of WG was low. Children and adolescents who consumed the most servings of WG had better diet quality and nutrient intake.
Idealized model for changes in equilibrium temperature, mixed layer depth, and boundary layer cloud over land in a doubled CO2 climate
Authors: Betts Alan K. , Chiu J. Christine
Published: October 2010

An idealized equilibrium model for the undisturbed partly cloudy boundary layer (BL) is used as a framework to explore the coupling of the energy, water, and carbon cycles over land in midlatitudes and show the sensitivity to the clear‐sky shortwave flux, the midtropospheric temperature, moisture, CO2, and subsidence. The changes in the surface fluxes, the BL equilibrium, and cloud cover are shown for a warmer, doubled CO2 climate. Reduced stomatal conductance in a simple vegetation model amplifies the background 2 K ocean temperature rise to an (unrealistically large) 6 K increase in near‐surface temperature over land, with a corresponding drop of near‐surface relative humidity of about 19%, and a rise of cloud base of about 70 hPa. Cloud changes depend strongly on changes of mean subsidence; but evaporative fraction (EF) decreases. EF is almost uniquely related to mixed layer (ML) depth, independent of background forcing climate. This suggests that it might be possible to infer EF for heterogeneous landscapes from ML depth. The asymmetry of increased evaporation over the oceans and reduced transpiration over land increases in a warmer doubled CO2 climate.
Predicting near‐surface atmospheric variables from Special Sensor Microwave/Imager using neural networks with a first‐guess approach
Authors: Roberts J. Brent , Clayson Carol Anne , Robertson Franklin R. , Jackson Darren L.
Published: October 2010

The turbulent heat fluxes play a pivotal role in the exchange of energy between the atmosphere and ocean. The calculation of these fluxes over the global oceans requires the use of bulk aerodynamic or flux‐gradient methods that rely on estimates of the sea surface temperature (SST), near‐surface wind speed, air temperature, and specific humidity. Errors in current methodologies of satellite retrievals of near‐surface properties have been shown to be the main sources of error for calculation of the fluxes. A new neural network technique is presented here that significantly improves the error characteristics of the air temperature and specific humidity compared to previous methods. Improvements in predicting near‐surface wind speed and SST are also seen. Additional improvements are also made by accounting for the effects of high cloud liquid water contents, the effects of which can be mitigated through the use of regime‐specific linear and nonlinear retrieval methods. The use of a first‐guess SST is shown to result in significant improvement in retrieval accuracy.
A heterogeneous land surface model initialization study
Authors: Shrestha Roshan , Houser Paul
Published: October 2010

Accurate energy and water storage initialization is critical for skillful land surface model prediction. A properly initialized model has equilibrium land surface states via spin‐up runs. The present study investigated aspects of spin‐up runs for the Noah Land Surface Model (LSM) at point stations using the 1 km grid of the Land Information System. The model is run repeatedly through a single year until a predefined equilibrium is achieved. Nine different model initialization methods were tested and compared in these spin‐up runs at twelve southern Great Plains surface observation stations in the Midwestern United States. Soil moisture is used as the primary land surface state to evaluate the spin‐up initializations. The model outputs are compared to evaluate the discrepancies over the annual cycle of repeated runs to learn how the model attains equilibrium land surface states. The results indicate that the climatological average state does not necessarily return the most efficient LSM initialization. Among the various tested methods, the spin‐up runs initialized with the spatially heterogeneous states averaged over a short period are found to perform better than others. Heterogeneous land surface conditions are also found to play a vital role in the spin‐up response. More stable land surface states are obtained through longer spin‐up runs, which also produce more similar coefficient of variance, suggesting that the longer spin‐up runs could yield similar heterogeneous fluxes irrespective of the initialization method. Comparing the results from different methods, a computationally economic technique for the single‐year spin‐up is proposed.
Bedrock erosion by root fracture and tree throw: A coupled biogeomorphic model to explore the humped soil production function and the persistence of hillslope soils
Authors: Gabet Emmanuel J. , Mudd Simon M.
Published: October 2010

In 1877, G. K. Gilbert reasoned that bedrock erosion is maximized under an intermediate soil thickness and declines as soils become thinner or thicker. Subsequent analyses of this “humped” functional relationship proposed that thin soils are unstable and that perturbations in soil thickness would lead to runaway thinning or thickening of the soil. To explore this issue, we developed a numerical model that simulates the physical weathering of bedrock by root fracture and tree throw. The coupled biogeomorphic model combines data on conifer population dynamics, rootwad volumes, tree throw frequency, and soil creep from the Pacific Northwest (USA). Although not hardwired into the model, a humped relationship emerges between bedrock erosion and soil thickness. The magnitudes of the predicted bedrock erosion rates and their functional dependency on soil thickness are consistent with independent field measurements from a coniferous landscape in the region. Imposed perturbations of soil erosion during model runs demonstrate that where bedrock weathering is episodic and localized, hillslope soils do not exhibit runaway thinning or thickening. The pit‐and‐mound topography created by tree throw produces an uneven distribution of soil thicknesses across a hillslope; thus, although episodes of increased erosion can lead to temporary soil thinning and even the exposure of bedrock patches, local areas of thick soils remain. These soil patches provide habitat for trees and serve as nucleation points for renewed bedrock erosion and soil production. Model results also suggest that where tree throw is a dominant weathering process, the initial mantling of bedrock is not only a vertical process but also a lateral process: soil mounds created by tree throw flatten over time, spreading soil over bedrock surfaces.
Contrasts in morphology and deformation offshore Montserrat: New insights from the SEA‐CALIPSO marine cruise data
Authors: Kenedi C. L. , Sparks R. S. J. , Malin P. , Voight B. , Dean S. , Minshull T. , Paulatto M. , Peirce C. , Shalev E.
Published: October 2010

During the December 2007, SEA‐CALIPSO experiment we collected seismic reflection profiles offshore of Montserrat. Off the east coast, we imaged deep fans of volcaniclastic debris from three volcanoes progressively active from ∼2 Ma to present. Near‐shelf sedimentation rates of 8–9 cm/ka are approximated following cessation of local volcanic activity. The fans were deposited on sediments with apparent dips towards the ESE‐trending Montserrat‐Havers fault system (MHFS) in southern Montserrat. The MHFS encloses the Soufrière Hills Volcano, has elevated crustal blocks at Roche's Bluff, St. Georges Hill, and Garibaldi Hill, and extends off the west coast. Off the west coast, the N‐dip of two faults supports a N‐dip interpretation for a major component of MHFS, the Belham Valley fault. We propose that local deformation is affected by stress redistributions consistent with a right‐stepping, sinistral en‐echelon fault system, but the interplay of transtension and magmatism has resulted in complex and evolving stress regimes.
Sodium ion exosphere of Mercury during MESSENGER flybys
Authors: Paral Jan , Trávníček Pavel M. , Rankin Robert , Schriver David
Published: October 2010

Two flybys of Mercury by the NASA MESSENGER spacecraft on January 14 and October 6, 2008 provide insight into the spatial distribution of the heavy ion exosphere around the planet. The relatively quiet solar wind conditions and interplanetary magnetic field (IMF) orientation allow us to compare “in situ” observations with numerical simulations. During each flyby, the IMF had a strong radial Sun‐Mercury direction but nonzero northward and southward components for the first (M1) and second (M2) flybys, respectively. We show that comparative studies of particle tracing in stationary electromagnetic fields from a self‐consistent hybrid kinetic model provide a good characterization of Mercury's sodium ion exosphere when compared with MESSENGER observations.
A case study on the possible altitude‐dependent effects of collisions on sodium airglow emission
Authors: Sarkhel S. , Sekar R. , Chakrabarty D. , Sridharan S.
Published: October 2010

Simultaneous observations of a narrowband sodium (Na) airglow photometer corresponding to the D2 line in conjunction with a Na lidar from Gadanki (13.5°N, 79.2°E), India, reveal episodic enhancements in Na airglow intensity during 1930–0142 Indian standard time (IST; IST = UT + 5.5 h) on 18–19 March 2007. This variation is drastically different from the average Na airglow intensity variation for that duration during that month. Interestingly, the Na airglow intensity variation is found to be well correlated with the Na atom concentration variation only at 93.6 km during the period 2312–0142 IST, a period closer to the measurement of mesospheric ozone by the Sounding of Atmosphere using Broadband Emission Radiometry (SABER) instrument on board the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite. Moreover, the correlation coefficient is not significant at 88.5 km, where the Na concentration is maximum. Estimations of the altitude profiles of the volume emission rate of Na airglow corresponding to the D2 line using measured parameters during local postmidnight hours reveal that the peak of volume emission rate is different from 93.6 km. It is suggested that the altitude variation in collisional quenching is needed to match the peak altitude of emission to the altitude where correlation between the Na atom concentration and Na airglow intensity is maximum. The fact that the measured atmospheric pressure reduces by a factor of ∼2.5 as altitude changes from 88.5 to 93.6 km supports this proposition. The case study brings out the sensitivity of Na airglow intensity to the altitude dependence of the collisional quenching that eventually affects Na airglow emission.
Physical mechanisms of compressional EMIC wave growth
Authors: McCollough J. P. , Elkington S. R. , Usanova M. E. , Mann I. R. , Baker D. N. , Kale Z. C.
Published: October 2010

On 29 June 2007, electromagnetic ion cyclotron (EMIC) waves were observed on the ground by the Canadian Array for Realtime Investigations of Magnetic Activity (CARISMA) network of magnetometers between L = 4 and L = 6 in response to a significant magnetospheric compression. Here a new MHD/particle method for studying EMIC wave growth in the magnetosphere is used to provide a detailed study of the compression event. We compare equatorial field line crossings of NASA's Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft and CARISMA observation sites to frequency‐integrated wave growth rates from the MHD/particle method. Simulated temperatures were constant in time, suggesting an absence of energizing processes during this event. Many particles experienced so‐called Shabansky orbits during this event, in which their drift motion was confined to high latitudes in the dayside magnetosphere. We propose a new nonenergizing process, driven by ions undergoing Shabansky orbits, for generating ion temperature anisotropies. In addition, the fundamental role of the plasmasphere in generating EMIC waves from the free energy of warm ion temperature anisotropies is discussed.
A transient narrow poleward extrusion from the diffuse aurora and the concurrent magnetotail activity
Authors: Lui A. T. Y. , Spanswick E. , Donovan E. F. , Liang J. , Liu W. W. , LeContel O. , Zong Q.‐G.
Published: October 2010

We report observation of a transient narrow auroral feature extruding from the poleward boundary of the diffuse aurora on March 19, 2009. It moved westward and poleward initially to form part of a vortex pattern, followed by its equatorward‐dawnward retreat later. During this auroral activity, THEMIS satellites, projected near the same magnetic local time of the auroral feature, detected appreciable plasma flows, increase in the ratio of the ion energy over the electron energy, and some enhancements of electrostatic waves. The plasma flows were initially duskward‐earthward and changed to duskward‐tailward later. The overall development of the observed plasma flow pattern was detected during the equatorward‐dawnward retreat of the auroral feature when the Alfvén transit time between the magnetotail and the ionosphere is taken into account. This suggests that THEMIS satellites remotely sensed a counter‐clockwise flow vortex (viewed from above the equatorial plane) in the magnetotail with decreasing strength. We suggest that the process generating the auroral feature is related to the flow vortex in association with the depletion of the electron energy relative to the ion energy and wave‐particle interaction. An estimate of the possible associated current density is made. We provide reasoning for this auroral feature to be an auroral streamer and not a “failed” transpolar arc.
Small and meso‐scale properties of a substorm onset auroral arc
Authors: Frey H. U. , Amm O. , Chaston C. C. , Fu S. , Haerendel G. , Juusola L. , Karlsson T. , Lanchester B. , Nakamura R. , Østgaard N. , Sakanoi T. , Séran E. , Whiter D. , Weygand J. , Asamura K. , Hirahara M.
Published: October 2010

We present small and meso‐scale properties of a substorm onset arc observed simultaneously by the Reimei and THEMIS satellites together with ground‐based observations by the THEMIS GBO system. The optical observations revealed the slow equatorward motion of the growth‐phase arc and the development of a much brighter onset arc poleward of it. Both arcs showed the typical particle signature of electrostatic acceleration in an inverted‐V structure together with a strong Alfvén wave acceleration signature at the poleward edge of the onset arc. Two THEMIS spacecraft encountered earthward flow bursts around the times the expanding optical aurora reached their magnetic footprints in the ionosphere. The particle and field measurements allowed for the reconstruction of the field‐aligned current system and the determination of plasma properties in the auroral source region. Auroral arc properties were extracted from the optical and particle measurements and were used to compare measured values to theoretical predictions of the electrodynamic model for the generation of auroral arcs. Good agreement could be reached for the meso‐scale arc properties. A qualitative analysis of the internal structuring of the bright onset arc suggests the operation of the tearing instability which provides a 'rope‐like' appearance due to advection of the current in the sheared flow across the arc. We also note that for the observed parameters ionospheric conductivity gradients due to electron precipitation will be unstable to the feedback instability in the ionospheric Alfvén resonator that can drive structuring in luminosity over the range of scales observed.
Assimilation of land surface temperature into the land surface model JULES with an ensemble Kalman filter
Authors: Ghent D. , Kaduk J. , Remedios J. , Ardö J. , Balzter H.
Published: October 2010

Land surface models have uncertainties due to their approximation of physical processes and the heterogeneity of the land surface. These can be compounded when key variables are inadequately represented. Land surface temperature (LST) is critical as it forms an integral component in the surface energy budget, water stress evaluation, fuel moisture derivation, and soil moisture–climate feedbacks. A reduction in the uncertainty of surface energy fluxes, and moisture quantification, is assumed to be achievable by constraining simulations of LST with observation data. This technique is known as data assimilation and involves the adjustment of the model state at observation times with measurements of a predictable uncertainty. In this paper, the validity of LST simulations in a regionalized parameterization of the land surface model Joint UK Land Environment Simulator (JULES) for Africa is assessed by way of a multitemporal intercomparison study with the Moderate Resolution Imaging Spectroradiometer (MODIS), the Advanced Along Track Scanning Radiometer (AATSR), and the Spinning Enhanced Visible and Infrared Imager (SEVIRI) thermal products, with a two‐thirds reduction in model bias found when soil properties are reparameterized. A data assimilation experiment of SEVIRI LST into the JULES model via an ensemble Kalman filter shows an improvement in the modeled LST, soil moisture, and latent and sensible heat fluxes. This paper presents the first investigation into reducing the uncertainty in modeling energy and water fluxes with the United Kingdom's most important land surface model, JULES, by means of data assimilation of LST.
Water ice at low to midlatitudes on Mars
Authors: Vincendon Mathieu , Forget François , Mustard John
Published: October 2010

In this paper, we analyze water ice occurrences at the surface of Mars using near‐infrared observations, and we study their distribution with a climate model. Latitudes between 45°S and 50°N are considered. Data from the Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Actitité and the Compact Reconnaissance Imaging Spectrometer for Mars are used to assess the presence of surface water ice as a function of location and season. A modeling approach combining the 1‐D and 3‐D versions of the General Circulation Model of the Laboratoire de Météorologie Dynamique de Jussieu is developed and successfully compared to observations. Ice deposits 2–200 μm thick are observed during the day on pole facing slopes in local fall, winter, and early spring. Ice extends down to 13° latitude in the Southern Hemisphere but is restricted to latitudes higher than 32° in the north. On a given slope, the pattern of ice observations at the surface is mainly controlled by the global variability of atmospheric water (precipitation and vapor), with local ground properties playing a lower role. Only seasonal surface ice is observed: no exposed patches of perennial ground ice have been detected. Surface seasonal ice is however sensitive to subsurface properties: the results presented in this study are consistent with the recent discovery of low‐latitude subsurface ice obtained through the analysis of CO2 frost.