bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonparametric ROC summary statistics for correlated diagnostic marker data
Authors: Tang Liansheng Larry , Liu Aiyi , Chen Zhen , Schisterman Enrique F. , Zhang Bo , Miao Zhuang
Published: October 2012

We propose efficient nonparametric statistics to compare medical imaging modalities in multi‐reader multi‐test data and to compare markers in longitudinal ROC data. The proposed methods are based on the weighted area under the ROC curve, which includes the area under the curve and the partial area under the curve as special cases. The methods maximize the local power for detecting the difference between imaging modalities. We develop the asymptotic results of the proposed methods under a complex correlation structure. Our simulation studies show that the proposed statistics result in much better powers than existing statistics. We apply the proposed statistics to an endometriosis diagnosis study. Copyright © 2012 John Wiley & Sons, Ltd.
Metaphorical Models for Limits to Growth and Industrialization
Authors: Morecroft John D. W.
Published: October 2012

In this paper, I present two system dynamics models and simulators to explore sustainability and limits to growth in industrial society. I first describe a small model of the fishing industry. I then use the same model as a metaphor to think about global growth and industrialization and to interpret the closed‐loop feedback structure and dynamics of Jay Forrester's World Dynamics model. This famously concise (yet dynamically intricate) model represents an industrial society whose growth is eventually curtailed. My approach with both models is to investigate the feedback structure surrounding investment policy. Building on this material, I examine the value of metaphorical models for interpreting puzzling phenomena in business and society. Finally, I discuss generic coordination problems in managing the growth of firms, industries and society. Copyright © 2012 John Wiley & Sons, Ltd.
Risk and residency influences on public support for florida panther recovery
Authors: Langin Cynthia , Jacobson Susan K.
Published: October 2012

Human expansion into core habitat of the Florida panther (Puma concolor coryi) increasingly threatens this endangered carnivore. To understand the social dimensions of the influence of humans' proximity to risk from panthers on public support for panther recovery, a telephone survey was conducted in March 2007 on a random sample of 802 Florida, USA, residents stratified by 1) location in core Florida panther habitat in Southwest Florida or noncore potential translocation sites in South Central Florida, and 2) rural or urban residence. Respondents reported a moderate intention to support panther recovery. Few attitudinal differences were found between urban versus rural and core versus noncore residents. However, core urban residents scored higher on a knowledge index than did rural residents. Regression analysis of behavioral intentions to support panther recovery identified management preferences, perceptions, subjective norm, knowledge, duration of Florida residence, and level of interest in wildlife as predictors. The resulting model (R2 = 0.42) is effective for predicting support and providing insight into the characteristics associated with willingness to support panther recovery. © 2012 The Wildlife Society.
Recent trends and strategies for state nongame checkoff funding in the United States
Authors: Kendrick Melissa M. , May Linda M. , Warren Robert J.
Published: October 2012

Growing stakeholder expectations along with decreased traditional funding have prompted state fish and wildlife agencies throughout the United States to develop alternative mechanisms to fund nongame programs. During March–May 2010, we collected responses from 42 state natural‐resource agencies to assess characteristics of nongame checkoff initiatives, evaluate recent levels of funding procured, and identify marketing efforts used during fiscal years 2004–2008. We found that 32 of the respondent states used tax checkoffs to secure nongame funding, and that the total donations they received exceeded US $7 million/year. Annual nongame checkoff contributions declined from 2004 to 2008. Reported levels of nongame checkoff funding varied among states, ranging from about US $20,000 to >US$ million in annual donations. Number of tax checkoffs per state ranged from 1 to 27, but we found no evidence of a significant relationship between the number of checkoffs in a state and nongame funding procured. Additionally, we failed to observe a correlation between nongame checkoff funding and per capita income or population density among states during 2008, but we did find a positive correlation between nongame checkoff funding and state population size during 2008 (R27 = 0.54; P = 0.002). The most widely used marketing approaches reported by states were Internet and print advertising, press releases, tax outlets, and television or radio advertising. States that included nongame checkoff logos on their income tax forms received greater average donations (US $400,877/yr) than did states that did not list logos (US $194,919/yr). We developed a list of funding recommendations for states to consider for enhancing nongame funding. © 2012 The Wildlife Society.
The learning curve in laparoscopic major liver resection
Authors: Kluger Michael D. , Vigano Luca , Barroso Ryan , Cherqui Daniel
Published: October 2012

Laparoscopic major hepatectomy remains a relatively rare operation because it is a difficult and technically demanding procedure, and a standard, safe, reproducible technique has not been widely adopted. This is compounded by “major hepatectomy” encompassing multiple different operations each with their own anatomic and procedural considerations. In 2010, we investigated our learning curve for laparoscopic liver resection. We found a significant increase in the number of major hepatectomies performed over a 12‐year period, with concurrent reductions in the use of hand‐assistance, pedicle clamping, median clamping time, median operative time, blood loss and morbidity. This learning curve was confirmed by a subsequent multinational study. Both hospital and surgeon volume have been shown to affect outcomes, and defining a sufficient number of repetitions before the learning curve plateaus is not easy for laparoscopic major hepatectomy. We recommend that laparoscopic competencies be developed upon a foundation of open liver surgery and that laparoscopic major hepatectomy should only be attempted after competency with less technically complex laparoscopic resections. A center advanced along its institutional learning curve provides the collective expertise necessary for safe patient selection and management. An environment with colleagues willing to share their acquired proficiency allows the surgeon to observe and critique his or her performance against colleagues. Also, the guidance of like‐minded surgeons supports technical development and improved outcomes. In conclusion, steady progress can be made along the learning curve through committed practice of increasingly complex tasks and with proper coaching in a high‐volume environment.
Are Psychology University Student Gamblers Representative of Non-university Students and General Gamblers? A Comparative Analysis
Authors: Gainsbury Sally M. , Russell Alex , Blaszczynski Alex
Published: October 2012

Students recruited from psychology undergraduate university populations are commonly used in psychology research, including gambling studies. However, the extent to which the use of this subpopulation produces findings that can be extrapolated to other groups is questionable. The present study was designed to compare results from university-recruited psychology student gamblers to those obtained from a sample of gamblers recruited from the general population that also included students. An online survey measuring gambling behavior and Internet gambling, attitudes and knowledge about gambling and problem gambling severity was posted on websites accessed by gamblers. Participants were recruited from two sources, a psychology undergraduate university population (n = 461) and online websites (n = 4,801). Results showed university-recruited students differed significantly from both adults and students recruited from the general population in respect to demographic variables and gambling behavior. Psychology undergraduate students were younger, more likely to be female, and had lower incomes. When relevant demographic variables were controlled, psychology undergraduate students were found to gamble less frequently, at different times, and to be at lower-risk for gambling-related problems, but had more irrational beliefs and more negative attitudes towards gambling than gamblers recruited from the general population. Results suggest that caution should be used in extrapolating findings from research using university-recruited psychology student gamblers to wide community populations due to differences related to gambling thoughts, attitudes and behaviors.
“Writing a Name in the Sky”: Rancière, Cavell, and the Possibility of Egalitarian Inscription
Authors: NORVAL ALETTA J.
Published: October 2012

Democratic theory is often portrayed as torn between two moments: that of disruption of rule, and the ordinary, ongoing institutionalization of politics. This dualism also marks contemporary democratic theory. In Jacques Rancière's theory of politics it takes the form of an emphasis on the ruptural qualities of the staging of novel democratic demands and the reconfiguration of the space of political argument. The reconfiguration of existing political imaginaries depends upon a moment of inscription, which remains underdeveloped in Rancière's work. Arguing that the possibility of inscription is indeed thematized in Rancière's more historical writings, but is often ignored by commentators, this article seeks to draw out the implications of a focus on inscription for democratic theory and practice. To flesh out this account, the article draws on Cavell's writings on exemplarity and the role of exemplars in fostering both critical reflection and the imagination of alternatives. The focus on such exemplars and an aversive, nonconformist ethos together facilitate a better understanding of what is required for such novel demands to be acknowledged and inscribed into democratic life.
A new ‘inquisition’? Police reform, urban transparency and house numbering in eighteenth-century Geneva
Authors: CICCHINI MARCO
Published: October 2012

As an administrative tool of police reform, the introduction of house numbering in eighteenth-century Geneva was the result of a broad desire for urban transparency that resulted in the production of a new ‘regime of visibility’. This article examines how the logic of ‘number’ transformed the way in which urban space was conceived, organized and governed. As a political technology, the spatial practice of house numbering enabled governmental officials to divide, count, identify and classify urban populations in order to regulate the spaces of circulation in the modern city. Although the city's house-numbering system is taken for granted by most of the town-dwellers today, the current study illustrates how these police techniques encountered considerable resistance when they were initially imposed during the latter half of the eighteenth century.
“That Magnificent Land of Sunshine, Health, and Wealth”: How U.S. Entrepreneurs Sold Cuba's Isle of Pines
Authors: Neagle Michael E.
Published: October 2012

At the start of the twentieth century, U.S. citizens began settling and investing on the Isle of Pines off the coast of Cuba. U.S. entrepreneurs who believed the Isle was or would become U.S. territory bought vast tracts from Spanish and Cuban landowners. They then subdivided the land and marketed it to farmers and middle-class Americans still in search of opportunity on a disappearing frontier. These landholding companies' promotions helped shape the assumptions and expectations of thousands of Americans who settled on the Isle over the next few decades. Companies portrayed the Isle as a tropical paradise safe for white settlement and ripe for development. They promised high returns-on-investment for those looking to engage in citrus production for export, as well as a healthful climate for those plagued by chronic illness. Some of these settlers publicly echoed landholding companies' portrayal and remained on the Isle for years. Others found the Isle's promise to be grossly exaggerated and returned to the United States feeling swindled by unscrupulous entrepreneurs. Although set in a foreign land, U.S. interest in the Isle reveals much about life in the United States, including the changing nature of expansion, the growing power of advertising, and middle-class discontent.
Quantitative aspects of variations of 1.5–6.0 MeV electrons in the outer radiation belt during magnetic storms
Authors: Yuan C. J. , Zong Q.‐G.
Published: October 2012

We have quantitatively investigated the radiation belt dynamic variations of 1.5–6.0 MeV electrons during 54 coronal mass ejection (CME)–driven storms from 1993 to 2003 and 26 corotating interaction region (CIR)–driven recurrent storms in 1995 by utilizing case and statistical studies based on the data from the SAMPEX satellite. It is found that the boundaries determined by fitting an exponential to the flux as a function of L shell obtained in this study agree with the observed outer and inner boundaries of the outer radiation belt. Furthermore, we have constructed the radiation belt content (RBC) index by integrating the number density of electrons between those inner and outer boundaries. According to the ratio of the maximum RBC index during the recovery phase to the prestorm average RBC index, we conclude that CME‐driven storms produce more relativistic electrons than CIR‐driven storms in the entire outer radiation belt, although the relativistic electron fluxes during CIR‐related storms are much higher than those during CME‐related storms at geosynchronous orbit.
Carbon dioxide and methane emissions from the Yukon River system
Authors: Striegl Robert G. , Dornblaser M. M. , McDonald C. P. , Rover J. A. , Stets E. G.
Published: October 2012

Carbon dioxide (CO2) and methane (CH4) emissions are important, but poorly quantified, components of riverine carbon (C) budgets. This is largely because the data needed for gas flux calculations are sparse and are spatially and temporally variable. Additionally, the importance of C gas emissions relative to lateral C exports is not well known because gaseous and aqueous fluxes are not commonly measured on the same rivers. We couple measurements of aqueous CO2 and CH4 partial pressures (pCO2, pCH4) and flux across the water‐air interface with gas transfer models to calculate subbasin distributions of gas flux density. We then combine those flux densities with remote and direct observations of stream and river water surface area and ice duration, to calculate C gas emissions from flowing waters throughout the Yukon River basin. CO2 emissions were 7.68 Tg C yr−1 (95% CI: 5.84 −10.46), averaging 750 g C m−2 yr−1 normalized to water surface area, and 9.0 g C m−2 yr−1 normalized to river basin area. River CH4 emissions totaled 55 Gg C yr−1 or 0.7% of the total mass of C emitted as CO2 plus CH4 and ∼6.4% of their combined radiative forcing. When combined with lateral inorganic plus organic C exports to below head of tide, C gas emissions comprised 50% of total C exported by the Yukon River and its tributaries. River CO2 and CH4 derive from multiple sources, including groundwater, surface water runoff, carbonate equilibrium reactions, and benthic and water column microbial processing of organic C. The exact role of each of these processes is not yet quantified in the overall river C budget.
Large‐scale splay faults on a strike‐slip fault system: The Yakima Folds, Washington State
Authors: Pratt Thomas L.
Published: October 2012

The Yakima Folds (YF) comprise anticlines above reverse faults cutting flows of the Miocene Columbia River Basalt Group of central Washington State. The YF are bisected by the ~1100‐km‐long Olympic‐Wallowa Lineament (OWL), which is an alignment of topographic features including known faults. There is considerable debate about the origin and earthquake potential of both the YF and OWL, which lie near six major dams and a large nuclear waste storage site. Here I show that the trends of the faults forming the YF relative to the OWL match remarkably well the trends of the principal stress directions at the end of a vertical strike‐slip fault. This comparison and the termination of some YF against the OWL are consistent with the YF initially forming as splay faults caused by an along‐strike decrease in the amount of strike‐slip on the OWL. The hypothesis is that the YF faults initially developed as splay faults in the early to mid Miocene under NNW‐oriented principal compressive stress, but the anticlines subsequently grew with thrust motion after the principal compressive stress direction rotated to N‐S or NNE after the mid‐Miocene. A seismic profile across one of the YF anticlines shows folding at about 7 km depth, indicating deformation of sub‐basalt strata. The seismic profile and the hypothesized relationship between the YF and the OWL suggest that the structures are connected in the middle or lower crust, and that the faults forming the YF are large‐scale splay faults associated with a major strike‐slip fault system.
Observed impacts of vertical velocity on cloud microphysics and implications for aerosol indirect effects
Authors: Lu Chunsong , Liu Yangang , Niu Shengjie , Vogelmann Andrew M.
Published: October 2012

The simultaneous measurements of vertical velocity and cloud droplet size distributions in cumuli collected during the RACORO field campaign over the Atmospheric Radiation Measurement Program's Southern Great Plains site near Lamont, Oklahoma, US, are analyzed to determine the effects of vertical velocity on droplet number concentration, relative dispersion (the ratio of standard deviation to mean radius), and their relationship. The results show that with increasing vertical velocity the droplet number concentration increases while the relative dispersion decreases. The data also exhibit a negative correlation between relative dispersion and droplet number concentration. These empirical relationships can be fitted well with power law functions. This observational study confirms the theoretical and numerical expectations of the effects of vertical velocity on cloud microphysics by analyzing the data of vertical velocity directly. The effects of vertical velocity on relative dispersion and its relationship with droplet number concentration are opposite to that associated with aerosol loading, posing a confounding challenge for separating aerosol indirect effects from dynamical effects.
Supershear rupture on multiple faults for the Mw 8.6 Off Northern Sumatra, Indonesia earthquake of April 11, 2012
Authors: Wang Dun , Mori Jim , Uchide Takahiko
Published: October 2012

We perform a back projection method to image the rupture propagation and short‐period energy release of the 2012 Off Northern Sumatra earthquake (Mw8.6) using Hi‐net data recorded in Japan. The results show a complex pattern of four conjugate faults over about 180 sec. There is a striking correspondence between the lengths and orientations of our rupture pattern with the distribution of aftershocks. Each of the first three stages of the rupture corresponds to a clear lineation in the aftershocks, with lengths of 200 to 400 km. Rupture speeds for several of the fault segments were very high, about 5 km/s, and exceed the local S‐wave velocity. This is the first example of an oceanic earthquake with supershear rupture speed.
Mantle flow uplift of western Anatolia and the Aegean: Interpretations from geophysical analyses and geodynamic modeling
Authors: Komut Tolga , Gray Robert , Pysklywec Russell , Göğüş Oğuz H.
Published: October 2012

The Western Anatolian and Aegean region demonstrates a complex geologic history of horizontal and vertical tectonics. Active normal faulting and exhumation zones indicate that Western Anatolia has experienced significant extension since the Oligocene‐Early Miocene (∼30 Ma). Our geophysical analyses demonstrate that the region is also uplifted relative to an elevation that would be expected given an isostatic response to the lithosphere structure. Namely, topography “residuals” indicate a residual uplift of about 1500 m over ∼200 km sections of Western Anatolia and the Aegean. Admittance functions between free‐air gravity and topography indicate that the regional topography is isostatically uncompensated and as it approaches ∼50 mGal/km at the longest wavelengths, the uncompensated topography is likely owing to an underlying mantle flow component. Using forward geodynamic modelling we consider an idealized section of Western Anatolian lithosphere based on tomographic inversions and examine the magnitude and pattern of surface topography to reconcile with the geophysical observables. The models consistently show a plateau‐type uplift (and horizontal extension) through Western Anatolia with an amplitude and wavelength consistent with the residual topography calculations. Together, the geophysical analyses and modelling provide independent quantitative evidence that the thin Anatolian‐Aegean lithosphere is being buoyed upwards by underlying mantle flow. The mantle flow may be associated with active lithosphere delamination beneath the region; a process that would also explain the ongoing crustal extension.
Optical characterization of water masses within the Columbia River plume
Authors: Palacios Sherry L. , Peterson Tawnya D. , Kudela Raphael M.
Published: October 2012

The Columbia River plume (CRP) is a buoyant plume that influences the Oregon and Washington shelf with the delivery of freshwater, silicic acid, trace metals, and particulate and dissolved organic matter. The highly dynamic plume contains submesoscale features that have an impact on the chemistry, biology, and transport of water and material offshore. Bio‐optical classification of the larger plume water mass has confirmed seasonal and annual flow patterns but has not described the internal structure of the plume in a biogeochemically relevant way, as there were no in situ data to validate classification. The objectives of this study were to define water types statistically within the CRP using in situ measurements of biogeochemically and bio‐optically relevant variables, to build a training data set from these water types, and to apply this training data set to 250 m resolution Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua imagery from an oceanographically downwelling and upwelling period to predictively discriminate water masses within the plume. This study's classification technique was effective at predicting water types in the CRP. The three‐variable input matrix (temperature, salinity, and chlorophyllafluorescence) performed better than the two‐variable input matrix (temperature and salinity) at distinguishing fine‐scale structure within the plume at the river mouth. Retentive features such as the plume bulge and eddies were observed at the river mouth and on the Washington shelf. This classification approach was limited to the available continuous variables measured by shipboard, mooring, and satellite sensors. Two new classification methods are proposed that build on the framework of the classifier described here.
Airborne observations of methane emissions from rice cultivation in the Sacramento Valley of California
Authors: Peischl J. , Ryerson T. B. , Holloway J. S. , Trainer M. , Andrews A. E. , Atlas E. L. , Blake D. R. , Daube B. C. , Dlugokencky E. J. , Fischer M. L. , Goldstein A. H. , Guha A. , Karl T. , Kofler J. , Kosciuch E. , Misztal P. K. , Perring A. E. , Pollack I. B. , Santoni G. W. , Schwarz J. P. , Spackman J. R. , Wofsy S. C. , Parrish D. D.
Published: October 2012

Airborne measurements of methane (CH4) and carbon dioxide (CO2) were taken over the rice growing region of California's Sacramento Valley in the late spring of 2010 and 2011. From these and ancillary measurements, we show that CH4 mixing ratios were higher in the planetary boundary layer above the Sacramento Valley during the rice growing season than they were before it, which we attribute to emissions from rice paddies. We derive daytime emission fluxes of CH4 between 0.6 and 2.0% of the CO2 taken up by photosynthesis on a per carbon, or mole to mole, basis. We also use a mixing model to determine an average CH4/CO2 flux ratio of −0.6% for one day early in the growing season of 2010. We conclude the CH4/CO2 flux ratio estimates from a single rice field in a previous study are representative of rice fields in the Sacramento Valley. If generally true, the California Air Resources Board (CARB) greenhouse gas inventory emission rate of 2.7 × 1010 g CH4/yr is approximately three times lower than the range of probable CH4 emissions (7.8–9.3 × 1010 g CH4/yr) from rice cultivation derived in this study. We attribute this difference to decreased burning of the residual rice crop since 1991, which leads to an increase in CH4 emissions from rice paddies in succeeding years, but which is not accounted for in the CARB inventory.
Modeling shortwave radiative fluxes from satellites
Authors: Ma Y. , Pinker R. T.
Published: October 2012

During the last two decades, significant progress has been made in assessing the Earth Radiation Balance from satellite observations. Yet, satellite based estimates differ from each other and from those provided by numerical models. Major issues are related to quality of satellite observations, such as the frequent changes in satellite observing systems, degradation of sensors, restricted spectral intervals and viewing geometry of sensors, and changes in the quality of atmospheric inputs that drive the inference schemes. To reduce differences among the satellite based estimates requires, among others, updates to inference schemes so that most recent auxiliary information can be fully utilized. This paper reports on improvements introduced to a methodology developed at the University of Maryland to estimate shortwave (SW) radiative fluxes within the atmosphere system from satellite observations, the implementation of the approach with newly available auxiliary information, evaluation of the downwelling SW flux against ground observations, and comparison with independent satellite methods and numerical models. Specifically, introduced are: new Narrow to Broadband (N/B) transformations and new Angular Distribution Models (ADM) for clear and cloudy sky that incorporate most recent land use classifications; improved aerosol treatment; separation of clouds by phase; improved sun‐earth geometry; and implementation at 0.5° spatial resolution at 3‐hourly intervals integrated to daily and monthly time scales. When compared to an earlier version of the model as implemented at 2.5° at global scale and against observations from the globally distributed Baseline Surface Radiation Network (BSRN) stations for a period of six years (at monthly time scale), the bias was reduced from 8.6 (4.6%) to −0.5 (0.3%) W/m2, the standard deviation from 16.6 (8.9%) to 14.5 (7.8%) W/m2while the correlation remained high at 0.98 in both cases. Evaluation was also done over oceanic sites as available from the Pilot Research Moored Array in the Tropical Atlantic (PIRATA) moorings and from the Tropical Atmosphere Ocean/Triangle Trans‐Ocean Buoy Network (TAO/TRITON) moorings in the tropical Pacific Ocean. Overall, results over oceans were not as good as over land for all the satellite retrievals compared in this study.
Physical and biological feedbacks of deforestation
Authors: Runyan Christiane W. , D'Odorico Paolo , Lawrence Deborah
Published: October 2012

Forest vegetation can interact with its surrounding environment in ways that enhance conditions favorable for its own existence. Removal of forest vegetation has been shown to alter these conditions in a number of ways, thereby inhibiting the reestablishment of the same community of woody plants. The effect of vegetation on an environmental variable along with vegetation susceptibility to the associated environmental conditions may imply a positive feedback: Changes in the internal conditions controlling this variable such as deforestation could inhibit the reestablishment of woody vegetation cover that in turn would act to further degrade the conditions necessary for forest regeneration. Understanding these feedbacks is important because in some cases where these feedbacks are present, deforestation can lead to irreversible state shifts where the forest vegetation cannot recover. In this review, we examine the different cases in which deforestation can lead to a loss of conditions necessary to sustain forest vegetation. We examine the spatial scale and extent of each feedback in addition to considering the temporal scale over which a feedback may be considered irreversible. Juxtaposing the spatial extent of these feedbacks with a map of deforestation enables the identification and discussion of at‐risk areas to state changes following deforestation. Last, we discuss the economic implications of these feedbacks and how socioeconomic factors can affect the convergence of a system to a given stable state.
Aquifer response to surface water transience in disconnected streams
Authors: Shanafield Margaret , Cook Peter G. , Brunner Philip , McCallum James , Simmons Craig T.
Published: October 2012

Existing analytical solutions to determine aquifer response to a change in stream stage are inappropriate where an unsaturated zone exists beneath the stream, as in the case of disconnected stream‐aquifer systems. A better understanding of the relationship between aquifer response and transient stream stage in disconnected systems is therefore required, as this would also aid in the field determination of the status of connection between the stream and aquifer. We use a numerical model to examine transient stream stage and the corresponding water table response. Beneath disconnected streams, the magnitude of head change in the water table level is a balance between the cumulative infiltration during a flow event and the rate at which the water can disperse laterally. Increases in wave duration, stream width, and streambed permeability result in greater infiltrated water volume and therefore a higher peak response at the water table. Conversely, higher aquifer transmissivity and aquifer hydraulic conductivity allow the water to move laterally away from the stream faster, resulting in a smaller head change below the stream. Lower unsaturated storage results in a greater and faster aquifer response because the unsaturated zone can fill more quickly. Under some combinations of parameters, the magnitude of the disconnected head response is more than seven times greater than the change in stream stage driving streambed infiltration; an effect which can never occur beneath a connected stream. The results of this sensitivity analysis are compared to field data from a river in eastern Australia to determine periods of disconnection. Where the change in aquifer head is greater than the change in stream stage, disconnection between the stream and aquifer can be determined.
Through thick and thin: the conundrum of chromatin fibre folding in vivo
Authors: Quénet Delphine , McNally James G , Dalal Yamini
Published: October 2012

The established view that chromatin is compacted into 30 nm fibres in the nucleus is being challenged. One of these studies is published in this issue of EMBO reports and shows that chromatin predominantly organizes as 10 nm fibres in somatic mouse cells. These recent data and their implications are discussed here.
Fungal community on decomposing leaf litter undergoes rapid successional changes
Authors: Voříšková Jana , Baldrian Petr
Published: October 2012

Fungi are considered the primary decomposers of dead plant biomass in terrestrial ecosystems. However, current knowledge regarding the successive changes in fungal communities during litter decomposition is limited. Here we explored the development of the fungal community over 24 months of litter decomposition in a temperate forest with dominant Quercus petraea using 454-pyrosequencing of the fungal internal transcribed spacer (ITS) region and cellobiohydrolase I (cbhI) genes, which encode exocellulases, to specifically address cellulose decomposers. To quantify the involvement of phyllosphere fungi in litter decomposition, the fungal communities in live leaves and leaves immediately before abscission were also analysed. The results showed rapid succession of fungi with dramatic changes in the composition of the fungal community. Furthermore, most of the abundant taxa only temporarily dominated in the substrate. Fungal diversity was lowest at leaf senescence, increased until month 4 and did not significantly change during subsequent decomposition. Highly diverse community of phyllosphere fungi inhabits live oak leaves 2 months before abscission, and these phyllosphere taxa comprise a significant share of the fungal community during early decomposition up to the fourth month. Sequences assigned to the Ascomycota showed highest relative abundances in live leaves and during the early stages of decomposition. In contrast, the relative abundance of sequences assigned to the Basidiomycota phylum, particularly basidiomycetous yeasts, increased with time. Although cellulose was available in the litter during all stages of decomposition, the community of cellulolytic fungi changed substantially over time. The results indicate that litter decomposition is a highly complex process mediated by various fungal taxa.
A decade of seasonal dynamics and co-occurrences within freshwater bacterioplankton communities from eutrophic Lake Mendota, WI, USA
Authors: Kara Emily L , Hanson Paul C , Hu Yu Hen , Winslow Luke , McMahon Katherine D
Published: October 2012

With an unprecedented decade-long time series from a temperate eutrophic lake, we analyzed bacterial and environmental co-occurrence networks to gain insight into seasonal dynamics at the community level. We found that (1) bacterial co-occurrence networks were non-random, (2) season explained the network complexity and (3) co-occurrence network complexity was negatively correlated with the underlying community diversity across different seasons. Network complexity was not related to the variance of associated environmental factors. Temperature and productivity may drive changes in diversity across seasons in temperate aquatic systems, much as they control diversity across latitude. While the implications of bacterioplankton network structure on ecosystem function are still largely unknown, network analysis, in conjunction with traditional multivariate techniques, continues to increase our understanding of bacterioplankton temporal dynamics.
A low-noise large dynamic-range readout suitable for laser spectroscopy with photodiodes
Authors: Pullia A. , Sanvito T. , Potenza M. A. , Zocca F.
Published: October 2012

An original low-noise large dynamic-range readout system for optical light spectroscopy with PIN diodes is presented. The front-end circuit is equipped with a smart device for automatic cancellation of the large dc offset brought about by the photodiode current. This device sinks away the exact amount of dc current from the preamplifier input, yielding auto zeroing of the output-voltage offset, while introducing the minimum electronic noise possible. As a result the measurement dynamic-range is maximized. Moreover, an auxiliary inspection point is provided which precisely tracks the dc component of the photodiode current. This output allows for precise beam alignment and may also be used for diagnostic purposes. The excellent gain stability and linearity make the circuit perfectly suited for optical-light pulse spectroscopy. Applications include particle sizing in the 100 nm range, two-dimensional characterization of semiconductor detectors, ultra-precise characterization of laser beam stability, confocal microscopy.
Influence of Fe segregation at grain boundaries on the magnetoresistance of Sr2Fe1+δMoO6 polycrystals
Authors: Kumar Nitu , Pandey Vibhav , Gaur Anurag , Kotnala R. K.
Published: October 2012

In this paper, we report the influence of Fe impurities on the magnetoresistance (MR) of double perovskite Sr2Fe1+δMoO6 (0.00 ≤ δ ≤ 0.20) system. The significant Fe impurities have been created by two different approaches: one by adding the extra amount of Fe2O3 at starting of the synthesis and other by sintering the pristine Sr2FeMoO6 sample at high temperature (1300 °C) in high reducing environment (∼8% H2 + 92% Ar). A remarkable 11% magnetoresistance at room temperature under the presence of low magnetic field (0.72 T) has been observed in the pristine sample. The achieved high low field magnetoresistance value in the sample may be due to the optimized synthesis conditions to get better inter-granular tunneling through grain boundaries. However, the presence of Fe impurity results into the sharp reduction in magnetoresistance because of reduced spin polarized tunneling. The loss of insulating nature of the grain boundaries and the inelastic scattering of the charge carriers through the metallic impurities of iron at grain boundaries may be the reason of reduced spin polarized tunneling.
An earth-isolated optically coupled wideband high voltage probe powered by ambient light
Authors: Zhai Xiang , Bellan Paul M.
Published: October 2012

An earth-isolated optically-coupled wideband high voltage probe has been developed for pulsed power applications. The probe uses a capacitive voltage divider coupled to a fast light-emitting diode that converts high voltage into an amplitude-modulated optical signal, which is then conveyed to a receiver via an optical fiber. A solar cell array, powered by ambient laboratory lighting, charges a capacitor that, when triggered, acts as a short-duration power supply for an on-board amplifier in the probe. The entire system has a noise level ⩽0.03 kV, a DC-5 MHz bandwidth, and a measurement range from −6 to 2 kV; this range can be conveniently adjusted.
Temperature peaking at beginning of breakdown in 2.45 GHz pulsed off-resonance electron cyclotron resonance ion source hydrogen plasma
Authors: Cortázar O. D. , Megía-Macías A. , Vizcaíno-de-Julián A.
Published: October 2012

An experimental study of temperature and density evolution during breakdown in off-resonance ECR hydrogen plasma is presented. Under square 2.45 GHz microwave excitation pulses with a frequency of 50 Hz and relative high microwave power, unexpected transient temperature peaks that reach 18 eV during 20 μs are reported at very beginning of plasma breakdown. Decays of such peaks reach final stable temperatures of 5 eV at flat top microwave excitation pulse. Evidence of interplay between incoming power and duty cycle giving different kind of plasma parameters evolutions engaged to microwave coupling times is observed. Under relative high power conditions where short microwave coupling times are recorded, high temperature peaks are measured. However, for lower incoming powers and longer coupling times, temperature evolves gradually to a higher final temperature without peaking. On the other hand, the early instant where temperature peaks are observed also suggest a possible connection with preglow processes during breakdown in ECRIS plasmas.
Shock initiation of the tri-amino-tri-nitro-benzene based explosive PBX 9502 cooled to −55 °C
Authors: Gustavsen Richard L. , Gehr Russell J. , Bucholtz Scott M. , Alcon Robert R. , Bartram Brian D.
Published: October 2012

We report a series of shock initiation experiments on PBX 9502 cooled to −55 °C. PBX 9502 consists of 95% dry aminated tri-amino-tri-nitro-benzene (TATB) and 5% poly-chloro-trifluoro-ethylene5 (Kel-F 800) binder. PBX 9502 samples were shock initiated by projectile impact from a two stage gas gun. Buildup to detonation was measured with 10 or more particle velocity gauges embedded at different depths in the sample. Three shock wave trackers measured the position of the shock front with time. Particle velocity vs. time wave-profiles and coordinates for onset of detonation were obtained as a function of the impact stress or pressure. PBX 9502 sample temperatures were monitored using type-E thermocouples, two inside the sample and two on the sample surface. Additional thermocouples were mounted on other parts of the cooling apparatus. Wave profiles from embedded gauges are qualitatively similar to those observed at 23 °C. However, at −55 °C, PBX 9502 is much less sensitive than at 23 °C. For example, at an inpact stress of 15.4 GPa, the distance to detonation at −55 °C is 7.8 mm. At 23 °C, the distance is 4.3 mm.
Comparative study of ultraviolet detectors based on ZnO nanostructures grown on different substrates
Authors: Abdulgafour H. I. , Hassan Z. , Ahmed N. M. , Yam F. K.
Published: October 2012

Pd/ZnO/Pd metal-semiconductor-metal photodetectors have been successfully fabricated using a variety of high-quality ZnO nanostructures. The nanostructures used included well-aligned nanorods, tetrapod-like nanorods, and hair-like nanowires and were synthesized on Si (100), porous silicon (PS/Si), and quartz substrates, respectively, using a catalyst-free vapor–solid mechanism for comparison. The morphological, structural, and optical properties of these nanostructures were investigated. Upon illumination with ultraviolet light (365 nm), the responsivity values of the fabricated photodetectors on PS/Si, Si, and quartz substrates were 0.22, 0.073, and 0.053 A/W, which correspond to quantum efficiencies of 85%, 28%, and 20%, respectively, at an applied bias of 5 V. The present study demonstrated that ZnO nanowires/PS exhibited a relatively fast photoresponse, with a rise time of 0.089 s and fall time of 0.085 s. The ZnO nanorods/Si and ZnO nanotetrapods/quartz exhibited a slow response, with rise times of 0.128 and 0.194 s and fall times of 0.362 and 0.4 s, respectively. The study suggests that the response time of the ZnO nanostructures to ultraviolet exposure is dependent on the type of substrate used. Results show that these nanostructures are suitable for sensing applications.
Simulation of non-linear recombination of charge carriers in sensitized nanocrystalline solar cells
Authors: Ansari-Rad M. , Abdi Y. , Arzi E.
Published: October 2012

Electron transport and recombination in electrolyte-filled sensitized nanocrystalline solar cell was investigated using Monte-Carlo simulation. Multiple-trapping in an exponential tail of trap states was used as an electron transport model. For simulation of the recombination, a new approach based on Marcus theory of charge transfer was developed and utilized to simulate both linear and non-linear (trap-assisted) recombination of electrons with holes in the electrolyte. Monte-Carlo simulation results, based on this approach, reproduced the non-constant diffusion length, recently observed in several experimental works. All simulation results were compared with theoretical predictions of the Marcus theory of charge transfer. Based on this comparison, interestingly it was found that random walk electron lifetime is different from the one which is obtained experimentally by small-perturbation techniques. This result is similar to the well-known Darken equation that describes the difference between jump and chemical diffusion coefficient. An interpretation based on the transport-limited recombination picture was provided to describe this result. These simulations establish a clear picture that describes how the localized trap states contribute to the recombination, leading to the non-linear recombination kinetics in sensitized solar cells.
Reduction in subsidy for solar power as distributed electricity generation in Indian future competitive power market
Authors: Kumar Sharma Naveen , Raj Sood Yog
Published: October 2012

Developed countries have seen renewable energy as a key tool for emission reduction as well as reducing reliance on oil, gas, and coal. Renewable energy sources (RESs) and technologies have potential to provide solutions to the longstanding energy problems being faced by the developing countries. In the future competitive electricity market for India, it becomes very much important to give special consideration for development of RESs due to economic, environmental, and other social problems related with conventional generations. Solar energy can be an important part of India's plan not only to add new capacity but also to increase energy security and lead the massive market for renewable energy. The major problem with solar power generation (SPG) is high cost of renewable generation. The Indian government is providing a lot of subsidy in order to encourage renewable energy generations. This paper presents an approach for reduction in subsidy of SPG used as distributed generator in competitive power market. The proposed approach has been validated with IEEE 14-bus and IEEE 30-bus systems.
Probing anisotropic heat transport using time-domain thermoreflectance with offset laser spots
Authors: Feser Joseph P. , Cahill David G.
Published: October 2012

An analytic solution is derived for the time-domain thermoreflectance signal that occurs using non-concentric pump and probe beams on multilayer anisotropic materials. When in-plane heat transport is negligible, the experimental signal is the same as for the concentric case. However, for samples where in-plane heat diffusion distances are comparable to the spot size, the signal is sensitive to in-plane heat transport. This sensitivity to in-plane transport can be exploited to measure the in-plane thermal conductivity. Examples with experimental data are given for thin-film Al and the in-plane thermal conductivity of pyrolytic graphite.
Multiphonon scattering and photoluminescence of two dimensional ZnS nanosheets grown within Na-4 mica
Authors: Mandal Amrita , Mitra Sreemanta , Datta Anindya , Banerjee Sourish , Dhara Sandip , Chakravorty Dipankar
Published: October 2012

Two dimensional wurtzite ZnS nanosheets with thickness of 0.6 nm are grown within the interlayer spaces of sodium fluorophlogopite mica (Na-4 mica) using ion-exchange-cum-solution treatment method followed by sulfidation treatment at 873 K. The presence of wurtzite ZnS is confirmed by x-ray diffraction, electron microscopy, and Raman scattering studies. The two dimensional form of ZnS gives rise to a strong quantum confinement with the band gap blue shifted by 1.7 eV. Thickness of the nanosheet is confirmed using atomic force microscopy. Raman scattering studies show higher order transverse optical modes due to increased deformation potential in reduced dimension. In contrast to red shift of optical phonon modes in phonon confinement model, a blue shift observed is ascribed to a compressive stress on ZnS nanosheets grown within Na-4 mica interlayer spaces. An additional band at 315 cm−1 is assigned to surface optical phonon. Unusual broadening in room temperature photoluminescence spectrum may be due to strong coupling of excitons with overtones of longitudinal optical phonon modes.