bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiple Exclusion Homelessness in the UK: Key Patterns and Intersections
Authors: Fitzpatrick Suzanne , Johnsen Sarah , White Michael
Published: August 2011

This article presents preliminary results from a multi-stage quantitative study of ‘multiple exclusion homelessness’ (MEH) in seven urban locations across the UK. It demonstrates a very high degree of overlap between a range of experiences associated with ‘deep social exclusion’ – namely, homelessness, substance misuse, institutional care and ‘street culture’ activities (such as begging and street drinking). It also provides evidence to support the contention that homelessness is a particularly prevalent form of exclusion, with its experience reported as widespread by those accessing low threshold support services targeted at other dimensions of deep exclusion, such as drug misuse. Further, the analysis presented indicates that the nature of MEH varies geographically, with the profile of the population affected looking quite different in Westminster (London) than in the other urban locations. The main explanation for this appears to be the exceptionally high proportion of migrants in the MEH population in Westminster, who tend to report lower overall levels of personal trauma and vulnerability than the indigenous MEH population.
Young People Living in the YMCA
Authors: Somerville Peter , Brown Philip , Morris Gareth , Scullion Lisa
Published: August 2011

This article presents interim findings and reflections from a case study of multiply excluded homeless people in Stoke-on-Trent. The article focuses on the experiences reported by a group of twelve such people living in the YMCA hostel. From the interviews, a large number of thematic structures were identified, of which only a few are outlined here, due to restrictions on the article length. The article concludes that the YMCA has had an important impact on their lives, mostly for the better, but the nature of this impact is complex and far from being fully understood.
Employability Pathways and Perceptions of ‘Work’ amongst Single Homeless and Vulnerably Housed People
Authors: McNeill Jenny
Published: August 2011

This article reports on a longitudinal study that explores the changing motivations to enter paid work of a sample of thirty homeless and vulnerably housed people. A pathways approach is proposed to offer insights into the complex relationships between promoting employability and the pursuit of other resettlement outcomes, such as the achievement of sustainable accommodation and recovery from long-term ill-health issues. The four pathways constructed following in-depth interviews suggest that individuals were at various stages of moving towards employment. Movement within and between pathways was affected by personal and structural issues, including access to resources, housing situations and support needs.
Review article: Homelessness and Housing Support Services: Rationales and Policies under New Labour
Authors: Dobson Rachael , McNeill Jenny
Published: August 2011

This discussion offers a thematic introduction and contextual framework across the welfare domains of homelessness and employment. The Labour Government (1997−2010) introduced a range of policies, which drew connections between homelessness and employment strategies. Such approaches were indicative of efforts to responsibilise and empower marginalised groups by way of conditional responses, which intended to steer clients towards independent and ‘active’ citizenship. In this context, work-related activities were regarded as transformative and meaningful. In broad terms, this approach can be understood as part of a wider set of therapeutic interventions that aimed to support clients with multiple support needs, albeit through somewhat coercive and regulatory overtones (Harrison and Sanders, 2006). A review of social policies developed under the Labour Government is useful for a critical understanding of welfare approaches and practices during that period, and it also enables us to evaluate how far there is continuity or change in approaches in successive political administrations. Labour introduced a set of policy principles that represented distinctive responses to disadvantaged groups, and this review highlights some of the key rationales and techniques of governance from that era. The conclusion will discuss the potential legacy for welfare policy, with specific reference to the Coalition Government.
Has the armed conflict in Afghanistan affected the rules on the conduct of hostilities?
Authors: Geiß Robin , Siegrist Michael
Published: August 2011

The armed conflict in Afghanistan since 2001 has raised manifold questions pertaining to the humanitarian rules relative to the conduct of hostilities. In Afghanistan, as is often the case in so-called asymmetric conflicts, the geographical and temporal boundaries of the battlefield, and the distinction between civilians and fighters, are increasingly blurred. As a result, the risks for both civilians and soldiers operating in Afghanistan are high. The objective of this article is to assess whether – and if so how much – the armed conflict in Afghanistan has affected the application and interpretation of the principles of distinction, proportionality, and precaution – principles that form the core of legal rules pertaining to the conduct of hostilities.
Detection of Differential Item Functioning
Authors: Prieto-Marañón Pedro , Ester Aguerri María , Silvia Galibert María , Félix Attorresi Horacio
Published: August 2011

This study analyzes Differential Item Functioning (DIF) with three combined decision rules and compares the results with the variation of the Mantel-Haenszel procedure (vaMH) proposed by Mazor, Clauser, and Hambleton (1994). One decision rule combines the Mantel-Haenszel procedure (MH) with the Breslow-Day test of trend in odds ratio heterogeneity (BDT), having performed the Bonferroni adjustment, as Randall Penfield proposed. The second uses both MH and BDT without the Bonferroni adjustment. The third combines MH with the Breslow-Day test for homogeneity of the odds ratio without the Bonferroni adjustment. The three decision rules yielded satisfactory results, showed similar power, and none of them detected DIF erroneously. The second rule proved to be the most powerful in the presence of nonuniform DIF. Only in the presence of uniform DIF with the smallest difference of difficulty parameters, was there evidence of vaMH’s superiority.
Assessing Content Validity Through Correlation and Relevance Tools
Authors: Gajewski Byron J. , Coffland Valorie , Boyle Diane K. , Bott Marjorie , Price Larry R. , Leopold Jamie , Dunton Nancy
Published: August 2011

Content validity elicits expert opinion regarding items of a psychometric instrument. Expert opinion can be elicited in many forms: for example, how essential an item is or its relevancy to a domain. This study developed an alternative tool that elicits expert opinion regarding correlations between each item and its respective domain. With 109 Registered Nurse (RN) site coordinators from National Database of Nursing Quality Indicators®, we implemented a randomized Bayesian equivalence trial with coordinators completing “relevance” or “correlation” content tools regarding the RN Job Enjoyment Scale. We confirmed our hypothesis that the two tools would result in equivalent content information. A Bayesian ordered analysis model supported the results, suggesting that evidence for traditional content validity indices can be justified using correlation arguments.
Change? What Change?
Authors: Lugtig Peter , Boeije Hennie R. , Lensvelt-Mulders Gerty J. L. M.
Published: August 2011

A primary objective of panel studies is to analyze change. The same questionnaire is used to compare data recorded at various times. Panel designs assume that the meaning of the questions and the concept of interest are stable over time. Analyses of measurement invariance often show the contrary. A qualitative part supplementing a panel survey can help us understand this phenomenon. In this study, 261 first-year psychology students completed questionnaires about their study motivation on two occasions; we interviewed some students as well. The survey showed that study motivation is not invariant over time. The qualitative data converged with the quantitative outcomes and explained the lack of invariance by the students’ overall transition during the first study year. We conclude that mixing quantitative and qualitative research methods for panel studies helps us understand change in constructs over time. We can study change at the macrolevel and better understand such change at the microlevel.
M3 spectral analysis of lunar swirls and the link between optical maturation and surface hydroxyl formation at magnetic anomalies
Authors: Kramer Georgiana Y. , Besse Sebastien , Dhingra Deepak , Nettles Jeffrey , Klima Rachel , Garrick‐Bethell Ian , Clark Roger N. , Combe Jean‐Philippe , Head James W. , Taylor Lawrence A. , Pieters Carlé M. , Boardman Joseph , McCord Thomas B.
Published: August 2011

We examined the lunar swirls using data from the Moon Mineralogy Mapper (M3). The improved spectral and spatial resolution of M3 over previous spectral imaging data facilitates distinction of subtle spectral differences, and provides new information about the nature of these enigmatic features. We characterized spectral features of the swirls, interswirl regions (dark lanes), and surrounding terrain for each of three focus regions: Reiner Gamma, Gerasimovich, and Mare Ingenii. We used Principle Component Analysis to identify spectrally distinct surfaces at each focus region, and characterize the spectral features that distinguish them. We compared spectra from small, recent impact craters with the mature soils into which they penetrated to examine differences in maturation trends on‐ and off‐swirl. Fresh, on‐swirl crater spectra are higher albedo, exhibit a wider range in albedos and have well‐preserved mafic absorption features compared with fresh off‐swirl craters. Albedoand mafic absorptions are still evident in undisturbed, on‐swirl surface soils, suggesting the maturation process is retarded. The spectral continuum is more concave compared with off‐swirl spectra; a result of the limited spectral reddening being mostly constrained to wavelengths less than ∼1500 nm. Off‐swirl spectra show very little reddening or change in continuum shape across the entire M3 spectral range. Off‐swirl spectra are dark, have attenuated absorption features, and the narrow range in off‐swirl albedos suggests off‐swirl regions mature rapidly. Spectral parameter maps depicting the relative OH surface abundance for each of our three swirl focus regions were created using the depth of the hydroxyl absorption feature at 2.82 μm. For each of the studied regions, the 2.82 μm absorption feature is significantly weaker on‐swirl than off‐swirl, indicating the swirls are depleted in OH relative to their surroundings. The spectral characteristics of the swirls and adjacent terrains from all three focus regions support the hypothesis that the magnetic anomalies deflect solar wind ions away from the swirls and onto off‐swirl surfaces. Nanophase iron (npFe0) is largely responsible for the spectral characteristics we attribute to space weathering and maturation, and is created by vaporization/deposition by micrometeorite impacts and sputtering/reduction by solar wind ions. On the swirls, the decreased proton flux slows the spectral effects of space weathering (relative to nonswirl regions) by limiting the npFe0 production mechanism almost exclusively to micrometeoroid impact vaporization/deposition. Immediately adjacent to the swirls, maturation is accelerated by the increased flux of protons deflected from the swirls.
Water isotopologues as a quantitative paleosalinity proxy
Authors: LeGrande Allegra N. , Schmidt Gavin A.
Published: August 2011

Paleosalinity reconstructions are a goal of paleoceanographic study because of their potential to provide insight into past ocean circulation. While temperature reconstructions have been assessed by using multiple independent proxies, the skill of existing salinity reconstructions remains poorly quantified. We examine the applicability of two different approaches using a set of coupled water isotope–enabled general circulation model experiments as a numerical analog for the real climate system. These simulations for the Holocene, at roughly 1000 year time steps, explicitly track variability in both the water isotopologues and salinity. Our simulations suggest that quantitative reconstructions of past salinity variability based solely on inferred δ18Osw variability have very large errors and uncertainties. However, we find that paired δ18Osw and δD variability (from combining biomarker and calcite proxies) holds promise for providing better quantitative estimates of salinity variability.
The response of the Walker circulation to Last Glacial Maximum forcing: Implications for detection in proxies
Authors: DiNezio P. N. , Clement A. , Vecchi G. A. , Soden B. , Broccoli A. J. , Otto‐Bliesner B. L. , Braconnot P.
Published: August 2011

The response of the Walker circulation to Last Glacial Maximum (LGM) forcing is analyzed using an ensemble of six coordinated coupled climate model experiments. The tropical atmospheric overturning circulation strengthens in all models in a manner that is dictated by the response of the hydrological cycle to tropical cooling. This response arises from the same mechanism that has been found to explain the weakening of the tropical circulation in response to anthropogenic global warming but with opposite sign. Analysis of the model differences shows that the ascending branch of the Walker circulation strengthens via this mechanism but vertical motion also weakens over areas of the Maritime Continent exposed due to lower sea level. Each model exhibits a different balance between these two mechanisms, and the result is a Pacific Walker circulation response that is not robust. Further, even those models that simulate a stronger Walker circulation during the LGM do not simulate clear patterns of surface cooling, such as La Niña‐like cooling or enhanced equatorial cooling, as proposed by previous studies. In contrast, the changes in the Walker circulation have a robust and distinctive signature on the tilt of the equatorial thermocline, as expected from zonal momentum balance. The changes in the Walker circulation also have a clear signature on the spatial pattern of the precipitation changes. A reduction of the east‐west salinity contrast in the Indian Ocean is related to the precipitation changes resulting from a weakening of the Indian Walker circulation. These results indicate that proxies of thermocline depth and sea surface salinity can be used to detect actual LGM changes in the Pacific and Indian Walker circulations, respectively, and help to constrain the sensitivity of the Walker circulation to tropical cooling.
Effects of notch‐filtering on the ELF sferics and the physical parameters
Authors: Huang Sung‐Ming , Hsu Chang‐Lien , Chen Alfred B. , Li Jingbo , Lee Li‐Jou , Yang Guo‐Liang , Wang Yun‐Ching , Hsu Rue‐Rou , Su Han‐Tzong
Published: August 2011

For ELF stations using hardware notch‐filters to suppress power‐grid emissions, the amplitude and the phase of the recorded sferics will inevitably be distorted. The phase shift causes the event time to move and hinders cross‐comparing of events between different platforms. Notch‐filtering also create fictitious dips in the current moment spectrum of the ELF sferics that lead to error in deducing the charge moment change (CMC) of the source discharge. To alleviate the effects of notch‐filtering, we use an elementary signal processing method to reconstruct the source signals and use lab‐generated ELF‐like signals to check the limitations of the reconstruction. The results indicate that the delay of signals due to the notch‐filtering module can be reliably restored, while the amplitude is less; but the reconstruction does restore the low frequency components of the sferics that are important for the CMC determination. Using the corrected event time, 20 associated sprites recorded by the ISUAL/FORMOSAT‐2 experiment during June to September of 2008 were found. Comparing with the notch‐filtered sferics, the reconstructed sferics are found to increase the current moment amplitude Iods by 69 ± 55%, reduce the time constant τ by 52 ± 15%, and lowers the CMC by 22 ± 21%, respectively. From the linear‐correlation of the sprite brightness and the CMC of the sprite‐producing positive lightning, a threshold CMC of ∼900 C‐km for sprite initiation is inferred based on the reconstructed sferic data; this threshold value is also 25% lower than that inferred using the notch‐filtered sferics.
Worldwide extremely low frequency magnetic field sensor network for sprite studies
Authors: Whitley Toby , Füllekrug Martin , Rycroft Michael , Bennett Alec , Wyatt Frank , Elliott Don , Heinson Graham , Hitchman Adrian , Lewis Andrew , Sefako Ramotholo , Fourie Pieter , Dyers Jaci , Thomson Alan , Flower Simon
Published: August 2011

The first measurements from a new globally distributed extremely low frequency magnetic field sensor network are presented. The recorded data demonstrate that the system observed lightning with continuing currents on a global scale with a timing accuracy of ∼30 μs. The network consists of four state of the art instruments at sites in Scotland, the United States, South Africa and Australia. Each instrument records the two horizontal magnetic field components (Bx and By) with a sampling frequency of 4 kHz. The first results show the typical electromagnetic signature of a transient airglow increase (sprite) above a thunderstorm in southern Europe which is simultaneously imaged with a video camera. A similar electromagnetic signature is recorded from a lightning discharge in central Africa, and it is also attributed to a sprite occurrence. Studies using this global network should advance lightning and sprite research considerably.
Efficient matrix filling of multilevel simply sparse method via multilevel fast multipole algorithm
Authors: Jiang Zhaoneng , Xu Yuan , Chen Ru‐shan , Fan Zhenhong , Ding Dazhi
Published: August 2011

In this paper, an improved multilevel simply sparse method (MLSSM) is proposed for solving electromagnetic scattering problems that are formulated using the electric field integral equation approach. Previously, the matrix filling procedure of the conventional MLSSM is based on the adaptive cross approximation (ACA) method. Although the ACA is more efficient than direct filling, it requires a longer filling time for the far‐field matrix than that of the multilevel fast multipole algorithm (MLFMA). Three problems with moderate electrical sizes are used to demonstrate that the far‐field matrix filling memory of the ACA is also higher than that of the MLFMA. Hence, the MLFMA is utilized to reduce both the far‐field matrix filling time and memory of the conventional MLSSM. Since the MLSSM recompresses the far‐field interaction matrix of the MLFMA, the matrix‐vector multiplication of the proposed method is more efficient than that of the MLFMA. Numerical results are presented to demonstrate the accuracy and efficiency of the proposed method.
Divergence‐conforming discretization of second‐kind integral equations for the RCS computation in the Rayleigh frequency region
Authors: Ubeda E. , Rius J. M.
Published: August 2011

The divergence‐conforming discretization in method of moments of the magnetic field integral equation (MFIE) shows huge inaccuracies in the computed radar cross section (RCS) at the very low or extremely low frequency regime. We justify theoretically that the presence of this error in the computed RCS can be mitigated to some extent for some sharp‐edged objects, where this discrepancy is most evident, through the adoption of uniformly triangular or quadrangular meshings. Moreover, we present two discretizations in method of moments of second‐kind integral equations that are free from these huge RCS inaccuracies: (1) a modified implementation of the conventional Rao‐Wilton‐Glisson (RWG) discretization of the MFIE that provides in two steps the static and dynamic current components so that the nonsolenoidal static contribution can be discarded in the far‐field computation; and (2) the loop‐star discretization in method of moments of the novel electric‐magnetic field integral equation (EMFIE) which provides inherently a null static nonsolenoidal current contribution whereby a static‐dynamic decomposition of the current is not required.
Localization, tracking, and imaging of targets in wireless sensor networks: An invited review
Authors: Viani F. , Rocca P. , Oliveri G. , Trinchero D. , Massa A.
Published: August 2011

Wireless sensor networks (WSNs) have shown many attractive features in a lot of real‐world applications that motivate their rapid and wide diffusion. One of the most challenging topics when dealing with WSNs is the localization and tracking of objects from measurements collected by the nodes themselves. Once distributed in a region without the knowledge of their positions, the nodes actively take part in the localization of the network as well as to the detection and monitoring of the presence and movements of targets lying within the sensed area. This paper reviews state‐of‐the‐art systems and approaches developed for WSN‐based localization and tracking of active as well as passive targets. The main focus is on systems that exploit the strength of the received signal, always available at the WSN nodes, without ad hoc or additional hardware. Recent strategies for WSN‐based imaging are discussed as well.
Improvement of retrieved FORMOSAT‐3/COSMIC electron densities validated by ionospheric sounder measurements at Jicamarca
Authors: Aragon‐Angel A. , Liou Y.‐A. , Lee C.‐C. , Reinisch B. W. , Hernández‐Pajares M. , Juan M. , Sanz J.
Published: August 2011

Inversion techniques applied to GPS‐LEO radio occultation data allow the retrieval of accurate and worldwide‐distributed refractivity profiles, which, in the case of the ionosphere, can be converted into electron densities providing information regarding the electron content distribution in this atmospheric region. In order to guarantee the accuracy of the electron density retrievals, two key points should be taken into account: the horizontal gradients of the electronic distribution and the topside electron content above the LEO orbit. The deployment in April 2006 of the satellite Constellation Observing System for Meteorology Ionosphere and Climate (FORMOSAT‐3/COSMIC), carrying GPS receivers on board, provides valuable radio occultation data with global and almost uniform coverage overcoming the sparsity of data from previous LEO missions (for instance, GPS/MET, CHAMP, and SAC‐C). This is also one of the main limitations of other sources providing direct observations, such as ionosondes. In this study, the improved Abel transform inversion is used to analyze derived ionospheric electron density profiles of the whole year 2007 in a scenario with very high electron density gradients: The neighboring area of Jicamarca (76.9°W, 12°S, dip latitude: 1°N), Perú, located at very low latitude and close to the geomagnetic equator, and the influence of the Appleton‐Hartree equatorial anomaly (Davies, 1990). Moreover, different strategies to account for the topside electron content in the occultation data inversion are compared and discussed, taking advantage of the availability of FORMOSAT‐3/COSMIC data sets and manually calibrated measurements from Jicamarca DPS. Statistical results show that for the current scenario the improvements are only about 10%, evidencing that the lack of colocation is one important source of error for the classical Abel inversion. Implications with respect to the plasmaspheric contribution have been derived from this data set analysis, in particular, the necessity to account for it specially when the Total Electron Content (TEC) is small.
Total electron content models and their use in ionosphere monitoring
Authors: Jakowski N. , Mayer C. , Hoque M. M. , Wilken V.
Published: August 2011

In Global Navigation Satellite Systems (GNSS) using L band frequencies, the ionosphere causes signal delays that correspond to link‐related range errors of up to 100 m. Whereas this error can be corrected in dual‐frequency measurements by a linear combination of L1 and L2 phases, in single‐frequency measurements, additional information is needed to mitigate the ionospheric error which is proportional to the total electron content (TEC) of the ionosphere. This information can be provided by TEC maps deduced from corresponding GNSS measurements or from model values. Besides direct range error correction in navigation and remote sensing applications, TEC or electron density models play a key role in ionospheric monitoring and forecasting. In this paper we discuss the development and use of TEC models for calibrating TEC, reconstructing reliable TEC maps, and forecasting TEC behavior based on GNSS measurements. European and global TEC maps and corresponding 1 h ahead forecasts are distributed via the operational space weather and ionosphere data service (http://swaciweb.dlr.de) to the international community. The Neustrelitz TEC Model is a basic approach for a family of regional and global TEC models used in different types of applications. The model approximates typical TEC variations depending on the location, time, and level of solar activity with only a few coefficients.
Different types of quasistationary formulations for time domain simulations
Authors: Koch S. , Weiland T.
Published: August 2011

For many practical examples in electromagnetics, quasistationary approximations to the full set of the Maxwell equations are valid. Applying such approximations reduces the level of mutual coupling between the separate equations and leads to different sets of differential equations for the specific case. Based on the resulting subsets of the Maxwell equations, numerous formulations in terms of fields and potentials can be obtained. As the type of differential equation is changed due to the approximation in general, appropriate time‐integration schemes need to be selected for the numerical solution of the specific problem. An overview of existing quasistationary formulations is given while a simple test model is used to compare the different formulations.
Self‐adaptive fast frequency sweep for the finite element analysis of waveguide modes
Authors: Schultschik A. , Farle O. , Konkel Y. , Dyczij‐Edlinger R.
Published: August 2011

This paper presents a self‐adaptive frequency sweep technique for the modal analysis of inhomogeneous electromagnetic waveguides over wide frequency bands. It rests on a multipoint order reduction approach for the finite element method and employs an adaptive scheme based on successive bisection to control the error in the propagation constants of the considered modes. The suggested approach is highly accurate and significantly faster than full finite element computations. Numerical examples are presented to validate the new method and to demonstrate the exponential convergence rate of the reduced‐order model.
Hybrid Fast Fourier Transform–plane wave based near‐field far‐field transformation for “body of revolution” antenna measurement grids
Authors: Schmidt C. H. , Laitinen T. A. , Eibert T. F.
Published: August 2011

Near‐field measurement and transformation techniques are widely applied to characterize radiation patterns of antennas. Spherical and cylindrical near‐field measurements have been researched extensively and various techniques with different probe compensation capabilities and complexities exist. Among those techniques applicable for (almost) arbitrary probes, the crucial computational efficiency has been achieved through the use of Fast Fourier Transform based preprocessing of the measurement data. It is shown in this paper that the Fast Fourier Transform based preprocessing can also be utilized in conjunction with the plane wave based fully probe‐corrected near‐field far‐field transformation with low numerical complexity. The collection of probe signals is split into smaller subsets for individual orthogonal azimuthal Fourier modes by an Inverse Fast Fourier Transform. These smaller subsets can be transformed to the far field very efficiently with full probe correction. The technique presented in this paper is applicable for arbitrary “body of revolution” antenna measurement grids, including the important cases of cylindrical and spherical measurement grids. The “body of revolution” grids are rotationally symmetric around the z‐axis and the probe signals must be available equidistantly in ϕ.
Rough surface scattering at low‐grazing incidence: A dedicated model
Authors: Saillard M. , Soriano G.
Published: August 2011

The rough surface radar cross section becomes very small at grazing incidence, since most part of the energy travels in the forward direction. We build a rigorous model that can estimate it accurately. It is based on a specific integral formalism, and applies to both low‐grazing incidence and scattering angles. Reference data are produced to test the validity of approximate models, and a technique for extrapolation is detailed.
The Campania‐Lucania Extensional Fault System, southern Italy: A suggestion for a uniform model of active extension in the Italian Apennines
Authors: Brozzetti F.
Published: August 2011

By integrating new field data, seismic lines interpretation and a critical review of the literature, this work highlights a regional array of normal faults in the southern Apennines of Italy, which have been active during the Quaternary and are referred to as the “Campania‐Lucania Extensional Fault System” (CLEFS). The CLEFS consists of three main NW‐SE striking alignments of normal faults, which for the first time are considered genetically linked and methodically described in their geometry, kinematics and displacement. The CROP04 seismic profile, crossing the central part of the CLEFS, was strictly constrained by detailed geological surveys and reinterpreted to define the downdip trajectory of the major normal faults. These latter have been observed to splay from an east dipping low‐angle detachment surface penetrating the upper crust to depths of 12–13 km. The time‐space evolution of the faults and the associated basins was defined through a review of the stratigraphic data on the syntectonic deposits. As regards the overall geometry and the associate sense of shear (top‐to‐east), the CLEFS sensibly differs from the extensional features described previously in this region but shows surprising affinities with the “Etrurian Fault System,” an extensional megastructure of the northern Apennines. Remarkable similarities concern the extent, the surface and subsurface geometry, the timing of activity and the amount of the associated deformation. These common characters recognized over a belt nearly 600 km long lead to formulation of a low‐angle normal fault–driven extension geometrical‐kinematic model, which is sound for the whole active extensional belt of Italy.
Lateral termination of the north‐directed Alpine orogeny and onset of westward escape in the Western Alpine arc: Structural and sedimentary evidence from the external zone
Authors: Dumont Thierry , Simon‐Labric Thibaud , Authemayou Christine , Heymes Thomas
Published: August 2011

The initial propagation of the Western Alpine orogen was directed northwestward, as shown by basement‐involved and Mesozoic sedimentary cover compressional structures and by the early foreland basins evolution. The crystalline basement of the Dauphiné zone recorded three shortening episodes: pre‐Priabonian deformation D1 (coeval with the Pyrenean‐Provence orogeny), and Alpine shortening events D2 (N‐NW directed) and D3 (W‐directed). The early Oligocene D2 structures are trending sub‐perpendicular to the more recent, arcuate orogen and are interfering with (or truncated by) D3, which marks the onset of westward lateral extrusion. The NW‐ward propagating Alpine flexural basin shows earliest Oligocene thin‐skinned compressional deformation, with syn‐depositional basin‐floor tilting and submarine removal of the basin infill above active structures. Gravity enhanced submarine erosion gave birth locally to steep submarine slopes overlain by kilometric‐scale blocks slid from the orogenic wedge. The deformations of the basin floor and the associated sedimentary and erosional features indicate a N‐NW‐ward directed propagation, consistent with D2 in the Dauphiné foreland. The Internal zones represent the paleo‐accretionary prism developed during this early Alpine continental subduction stage. The early buildup has been curved in the arc and rapidly exhumed during the Oligocene collision stage. Westward extrusion and indenting by the Apulian lithosphere allowed the modern arc to crosscut the western, lateral termination of the ancient orogen from ∼32 Ma onward. This contrasted evolution leads to propose a palinspastic restoration taking in account important northward transport of the distal passive margin fragments (Briançonnais) involved in the accretionary prism before the formation of the Western Alps arc.
Deep resistivity cross section of the intraplate Atlas Mountains (NW Africa): New evidence of anomalous mantle and related Quaternary volcanism
Authors: Anahnah Farida , Galindo‐Zaldívar Jesus , Chalouan Ahmed , Pedrera Antonio , Ruano Patricia , Pous Jaume , Heise Wiebke , Ruiz‐Constan Ana , Benmakhlouf Mohamed , López‐Garrido Angel Carlos , Ahmamou M'Fedal , Sanz de Galdeano Carlos , Arzate Jorge , Ibarra Pedro , González‐Castillo Lourdes , Bouregba Naoual , Corbo Fernando , Asensio Eva
Published: August 2011

The Atlas Mountains are characterized by high elevations and Quaternary volcanism. Long period magnetotelluric data acquired along a NNW‐SSE transect reveal the presence of a conductive anomalous mantle below the High Atlas. Data dimensionality analyses show a preferent N80°E strike of the deep resistivity structure in agreement with the induction vector alignment at long periods. Accordingly, a 2D inversion of the data set was carried out. Large resistive bodies at the crustal basement most likely correspond to batholiths emplaced in more conductive metapelites. They are covered by outcropping conductive sedimentary detritic and carbonate rocks. Lithospheric thinning producing anomalous mantle and basin development in the Atlas probably started during Triassic‐Jurassic rifting. Inversion tectonics since the Oligocene produced low shortening on previous lithospheric weak zones, with thrusting of the Atlas above the stable African plate. Melting at the top of the anomalous mantle is connected with Quaternary basaltic volcanism in the Middle Atlas.
Joint estimation of transmissivity and storativity in a bedrock fracture
Authors: Castagna Marta , Becker Matthew W. , Bellin Alberto
Published: August 2011

The spatial variability of transmissivity (T) and storativity (S) in a sandstone bedding plane fracture was investigated through field and numerical hydraulic tomography experiments. Cross‐hole pumping tests were conducted in a single subhorizontal bedrock fracture, thereby constraining the problem to two dimensions. A Bayesian method implementing pilot points was used to invert the drawdown, under the hypothesis that T and S are independent random space functions, where integral scale, mean, and variance of the random fields were parameters of inversion in addition to pilot point values. An ensemble of 20 Monte Carlo realizations was created for each model scenario. Inversion of the measured cross‐hole drawdown resulted in spatially variable T and S fields. To determine the accuracy of the method, a suite of synthetic inversions modeled after the field site were also conducted. The synthetic experiments demonstrate that the assumed spatial structure of S influences the accuracy of both the T and S inversions. When the S field is spatially heterogeneous and is assumed to be heterogeneous in the inversion, a consistent representation of the T and S fields is obtained. When the S field is spatially heterogeneous but is assumed to be homogeneous in the inversion, a consistent representation of the T field is still obtained, but the S field is entirely misrepresented; if the S field is actually homogeneous but assumed to be heterogeneous, a poor representation of the T and S fields is obtained along with high uncertainty in the inversion statistics of confidence.
Length of 3‐D mixing‐controlled plumes for a fully penetrating contaminant source with finite width
Authors: Liedl R. , Yadav P. K. , Dietrich P.
Published: August 2011

An analytical 3‐D model is developed to estimate steady state plume lengths in contaminated aquifers for the case of an instantaneous bimolecular reaction. The developed model generalizes the previous vertically‐oriented 2‐D model of Liedl et al. (2005) by considering a source that has finite width (2W) and is extended over the entire depth (M) of the aquifer. It is shown that the model of Liedl et al. (2005) overestimates steady state plume lengths if the source width is below a certain maximum relevant source width (2Wrel). Results also suggest that the ratio of the bulk transverse dispersivities in the horizontal and vertical directions is critical in defining the size of the plume, and that the maximum plume length is observed when 2W and M are approximately equal for any ratio above 10.
Usefulness of historical information for flood frequency analyses: Developments based on a case study
Authors: Payrastre O. , Gaume E. , Andrieu H.
Published: August 2011

This paper illustrates how historical information on floods can be retrieved in the a priori unfavourable case of small and sparsely populated catchments, and how this information can improve the estimation of flood discharge quantiles. It is based on the analysis of four small gauged rivers located in the south of France. Using various sources of archives, the flood discharges were estimated for past historical periods ranging from 100 to 200 years. The corresponding historical discharge series were then used in combination with the available systematic measurement series to evaluate peak discharge quantiles. The selected Bayesian Monte Carlo Markov Chain statistical inference approach provides credibility intervals for the estimated quantiles, the width of which reflects the information content of the data set used for the inference. The use of the historical data in the inference procedure leads to significant reductions of these credibility intervals, even if limitations in the content of historical inventories are introduced. A sensitivity analysis is conducted in the second part of the paper to evaluate to what extent these positive conclusions on the added value of historical data for flood frequency analysis can be extrapolated to other case studies. The influence of the number of historical floods documented (perception threshold) and of the level of knowledge of historical flood peak discharges is studied. The results are consistent with the previous works on the same issue and explain why these works led to apparently contradictory conclusions concerning the possible usefulness of historical data in flood frequency studies.
A water isotope approach to assessing moisture recycling in the island‐based precipitation of Taiwan: A case study in the western Pacific
Authors: Peng Tsung‐Ren , Liu Kon‐Kee , Wang Chung‐Ho , Chuang Kai‐Hsun
Published: August 2011

This study employs a dual‐isotope ( and ), three‐end‐member linear mixing model to semiquantitatively assess vapor contributions of advection, transpiration, and evaporation to precipitation, and to compare the extent of moisture recycling (including transpiration and evaporation) among areas of various topographic types in Taiwan, an island located in the western Pacific. The three topographic types examined are the mountainous regions, foothill regions (as represented by two reservoir stations), and coastal plains. Results indicate that the moisture fractions from advection and evapotranspiration in mountain precipitations are about 63% and 37%, respectively, and those in precipitation of plain and foothill regions are about 69% and 31%, respectively. Moreover, transpiration accounts for most of the recycling moisture while evaporation offers minor contribution. Since the transpiration fraction of recycling moisture is higher in forest mountain area than in plain/foothill region, topographic type is the major factor affecting the extent of transpiration. Nevertheless, the two reservoirs examined in this study do not offer significant contribution of recycling moisture to local precipitation. In addition to topographic type, temperature and rainfall may be two other factors controlling the extent of transpiration; transpiration would be promoted in greater rainfall regions but reduced in higher temperature areas. Additionally, about 25% of precipitation in plain/foothill region is of relocated moisture from evapotranspiration induced from forest mountains. It should be noted that this isotope‐based approach has its limitations and should be applied with caution.
Hydrological ensemble forecasting in mesoscale catchments: Sensitivity to initial conditions and value of reforecasts
Authors: Fundel Felix , Zappa Massimiliano
Published: August 2011

Hydrological forecasts can benefit from model climatologies compiled from long, consistent, retrospective forecasts (reforecasts). Typical areas of application include the estimation of return periods for extreme events, the detection of model deficiencies, such as systematic errors or the calibration of current forecasts using the reforecasts, and suitable observations. One difficulty when creating long reforecasts is the availability of good states for the model initialization, as a sufficiently dense network of meteorological observations is rarely available in most catchments for a long period. With this study, the creation of forecast and reforecasts in such catchments is motivated by considering two aspects: first, a comparison where it is shown that hydrological forecasts benefit most from high‐quality initial conditions on the basis of local observations, however, less accurate initial conditions using ERA‐interim reanalysis are also sufficient to provide skillful hydrological forecasts useful for many users. Second, we demonstrate that hydrological reforecasts compiled without long‐term meteorological observations have an additional value, e.g., they allow for more skillful runoff forecasts. Utilizing those reforecasts can compensate for forecast errors induced by less accurate initializations. For this study, hourly hydrological reforecasts, based on the PREcipitation‐Runoff‐EVApotranspiration HRU Model (PREVAH) were used, with an 18 year long, five‐member global ensemble reforecast data set from the European Centre for Medium Range Weather Forecasts (ECMWF) Variable Resolution Ensemble Prediction System (VarEPS) as forcing for lead times up to 10 days. Three mesoscale catchments of different characteristics in the Swiss Alps were analyzed.
Wind and ship wave‐induced resuspension in the littoral zone of a large lake
Authors: Hofmann Hilmar , Lorke Andreas , Peeters Frank
Published: August 2011

Sediment resuspension in lake littoral zones (nearshore region) is strongly related to the properties of the surface wavefield. The occurrence and characteristics of surface waves, near‐bottom current velocities, and related suspended sediment concentrations and properties were measured simultaneously in Lake Constance over 1 year. Wind and ship waves are distinguished on the basis of their typical properties, enabling a detailed investigation of their respective importance for sediment resuspension. In the littoral zone of Lake Constance, resuspension occurred during 25% of the entire observation period. Of those observations, 54% were caused by ship waves, which therefore were as important for resuspension as wind waves. Resuspension induced by wind waves occurs rather sporadically throughout the year, whereas ship wave‐induced resuspension occurs regularly during the daytime in summer and is hence associated with pronounced diurnal and seasonal patterns in the suspended sediment concentration.
How can subsurface modifications to hydraulic conductivity be designed as stream restoration structures? Analysis of Vaux's conceptual models to enhance hyporheic exchange
Authors: Ward Adam S. , Gooseff Michael N. , Johnson Peggy A.
Published: August 2011

Despite the growing interest in hyporheic exchange and the associated stream ecosystem processes, few studies consider restoration of hyporheic exchange as a design goal. Here we study the design of three types of subsurface structures for hyporheic restoration after conceptual designs published over 40 years ago. Vaux's designs involve modifying the subsurface with low or high hydraulic conductivity material placed at the streambed or adjacent to a confining layer below the stream. In this preliminary analysis of subsurface structure design we use two‐dimensional groundwater flow modeling of structures to simulate structure performance in plane bed streams for ranges of structure geometric design and hydraulic conductivities. Structure performance is evaluated on the basis of total streambed flux, physical extent of hyporheic flow paths created, and residence time distributions along flow paths modified by the structures. High hydraulic conductivity structures bend flow paths toward and through the structures themselves; performance is controlled by the structure hydraulic conductivity. Results show low hydraulic conductivity structure performance is insensitive to the structure material; hyporheic exchange is created by deflecting flow paths away from the structure itself. Time scales of simulated exchange are great enough to promote nitrification, denitrification, respiration, and thermal buffering in the subsurface, though these processes will also be controlled by site‐specific chemical and biological factors. General design recommendations for specific restoration objectives are presented. Results of this study can be extrapolated to further understand the interaction of natural subsurface heterogeneities (e.g., clay and gravel deposits and bedrock knickpoints) and flow fields in creating hyporheic flow paths.
Statistical applications of physically based hydrologic models to seasonal streamflow forecasts
Authors: Rosenberg Eric A. , Wood Andrew W. , Steinemann Anne C.
Published: August 2011

Despite advances in physically based hydrologic models and prediction systems, long‐standing statistical methods remain a fundamental component in most operational forecasts of seasonal streamflow. We develop a hybrid framework that employs gridded observed precipitation and model‐simulated snow water equivalent (SWE) data as predictors in regression equations adapted from an operational forecasting environment. We test the modified approach using the semidistributed variable infiltration capacity hydrologic model in a case study of California's Sacramento River, San Joaquin River, and Tulare Lake hydrologic regions. The approach employs a principal components regression methodology, adapted from the Natural Resources Conservation Service, which leverages the ability of the distributed model to provide an added dimension to SWE predictors in a statistical framework. Hybrid forecasts based on data simulated at grid points acting as surrogates for ground‐based observing stations are found to perform comparably to those based on their observed counterparts. When a larger selection of grid points are considered as potential predictors, hybrid forecasts achieve superior skill, with the largest benefits in watersheds that are poorly represented in terms of ground‐based observations. Forecasts are also found to offer overall improvement over those officially issued by California's Department of Water Resources, although their specific performance in dry years is less consistent. The study demonstrates the utility of physically based models within an operational statistical framework, as well as the ability of the approach to identify locations with strong predictive skill for potential ground station implementation.