bluuebunny/crossref_metadata_2025 huggingface dataset:
Periodicity in the BrO∕SO2 molar ratios in the volcanic gas plume of Cotopaxi and its correlation with the Earth tides during the eruption in 2015
Authors: Dinger Florian , Bobrowski Nicole , Warnach Simon , Bredemeyer Stefan , Hidalgo Silvana , Arellano Santiago , Galle Bo , Platt Ulrich , Wagner Thomas
Published: March 2018

Abstract. We evaluated NOVAC (Network for Observation of Volcanic and Atmospheric Change) gas emission data from the 2015 eruption of the Cotopaxi volcano (Ecuador) for BrO∕SO2 molar ratios. The BrO∕SO2 molar ratios were very small prior to the phreatomagmatic explosions in August 2015, significantly higher after the explosions, and continuously increasing until the end of the unrest period in December 2015. These observations together with similar findings in previous studies at other volcanoes (Mt. Etna, Nevado del Ruiz, Tungurahua) suggest a possible link between a drop in BrO∕SO2 and a future explosion. In addition, the observed relatively high BrO∕SO2 molar ratios after December 2015 imply that bromine degassed predominately after sulfur from the magmatic melt. Furthermore, statistical analysis of the data revealed a conspicuous periodic pattern with a periodicity of about 2 weeks in a 3-month time series. While the time series is too short to rule out a chance recurrence of transient geological or meteorological events as a possible origin for the periodic signal, we nevertheless took this observation as a motivation to examine the influence of natural forcings with periodicities of around 2 weeks on volcanic gas emissions. One strong aspirant with such a periodicity are the Earth tides, which are thus central in this study. We present the BrO∕SO2 data, analyse the reliability of the periodic signal, discuss a possible meteorological or eruption-induced origin of this signal, and compare the signal with the theoretical ground surface displacement pattern caused by the Earth tides. Our central result is the observation of a significant correlation between the BrO∕SO2 molar ratios with the north–south and vertical components of the calculated tide-induced surface displacement with correlation coefficients of 47 and 36 %, respectively. From all other investigated parameters, only the correlation between the BrO∕SO2 molar ratios and the relative humidity in the local atmosphere resulted in a comparable correlation coefficient of about 33 %.
An investigation of the thermomechanical features of Laohugou Glacier No. 12 on Qilian Shan, western China, using a two-dimensional first-order flow-band ice flow model
Authors: Wang Yuzhe , Zhang Tong , Ren Jiawen , Qin Xiang , Liu Yushuo , Sun Weijun , Chen Jizu , Ding Minghu , Du Wentao , Qin Dahe
Published: March 2018

Abstract. By combining in situ measurements and a two-dimensional
thermomechanically coupled ice flow model, we investigate the
thermomechanical features of the largest valley glacier (Laohugou
Glacier No. 12; LHG12) on Qilian Shan located in the arid region
of western China. Our model results suggest that LHG12, previously
considered as fully cold, is probably polythermal, with a lower
temperate ice layer overlain by an upper layer of cold ice over
a large region of the ablation area. Modelled ice surface velocities
match well with the in situ observations in the east branch (main
branch) but clearly underestimate those near the glacier terminus,
possibly because the convergent flow is ignored and the basal sliding
beneath the confluence area is underestimated. The modelled ice
temperatures are in very good agreement with the in situ
measurements from a deep borehole (110 m deep) in the upper
ablation area. The model results are sensitive to surface thermal
boundary conditions, for example surface air temperature and
near-surface ice temperature. In this study, we use a Dirichlet
surface thermal condition constrained by 20 m borehole
temperatures and annual surface air temperatures. Like many other
alpine glaciers, strain heating is important in controlling the
englacial thermal structure of LHG12. Our transient simulations
indicate that the accumulation zone becomes colder during the last two
decades as a response to the elevated equilibrium line altitude and
the rising summer air temperatures. We suggest that the extent of
accumulation basin (the amount of refreezing latent heat from
meltwater) of LHG12 has a considerable impact on the englacial thermal
status.
What historical landfast ice observations tell us about projected ice conditions in Arctic Archipelagoes and marginal seas under anthropogenic forcing
Authors: Laliberté Frédéric , Howell Stephen E. L. , Lemieux Jean-François , Dupont Frédéric , Lei Ji
Published: March 2018

Abstract. Arctic landfast ice extent and duration from observations, ice assimilations, ocean re-analyses and coupled models are examined. From observations and assimilations, it is shown that in areas where landfast ice conditions last more than 5 months the first-year ice grows typically to more than 2 m and is rarely less than 1 m. The observed spatial distribution of landfast ice closely matches assimilation products but less so for ocean re-analyses and coupled models. Although models generally struggle to represent the landfast ice necessary to emulate the observed sea ice dynamics in regions favourable to landfast ice conditions, some do exhibit both a realistic climatology and a realistic decline of landfast ice extent under an anthropogenic forcing scenario. In these more realistic simulations, projections show that an extensive landfast ice cover should remain for at least 5 months of the year well until the end of the 21st century. This is in stark contrast with the simulations that have an unrealistic emulation of landfast ice conditions. In these simulations, slow and packed ice conditions shrink markedly over the same period. In all simulations and in areas with landast ice that last more than 5 months, the end-of-winter sea ice thickness remains between 1 m and 2 m well beyond the second half of the century. It is concluded that in the current generation of climate models, projections of winter sea ice conditions in the Canadian Arctic Archipelago and the Laptev Sea are overly sensitive to the representation of landfast ice conditions and that ongoing development in landfast ice parametrization will likely better constrain these projections.
Governance, Good Governance, Organized Leadership and Meaningful Development: The Nigerian Experience
Authors: Ganiyu Adamson Duncan , Godowolli Halima A. , Oritsedurotimi Lawal Joy
Published: March 2018

This paper discusses how the process of governance in Nigeria over the years has been characterized by many negative indications, while the world which our government is pretending to copy is fast entrenching in every facet of its laws and practices the sanctity of life. It also discusses how our electoral and political machinery are legitimizing murder as an acceptable paradigm of settlement of even minor brushes. Governance is supposed to be articulate and organized leadership to culminate meaningful development that will bring the greatest happiness for the greatest number of people. Methodologically, the study was carried out using content analysis. Various existing document such as, historical evidence, newspaper reports, journal and existing archival records were content analyzed. Thus, while democracy in Nigeria is but a sham, good governance is still far in coming. The paper found out that the political class has continued to dispose and demonstrate known military attribute like corruption, civil authoritarianism, democratic dictatorship, brazen disrespect for human life, which have led to incessant killings as a political strategy. Rather than produce good governance that will develop the State, the above scenario has produced bad governance and further increased the poverty of the Nigerian populace. The paper recommended a general reconstruction of Nigeria’s political, social and economic infrastructure.
In Pursuit of Public Sector Efficiency and Value Innovation; the Blue Ocean Strategy
Authors: Kong Yusheng , Lartey Peter Yao , Bah Fatoumata Binta Maci , Biswas Nirmalya B. , Jaladi Rupa Santosh
Published: March 2018

This paper examines key institutional drivers capable of fashioning an enabling environment for public sector efficiency. The study gathered evidence that  institutional variables such as Innovation, Performance orientation, Value Creation and Budget Flexibility are good predictors of public sector efficiency. The extracted variables per the Factor Analysis accounted for 77.3% variance. Implying that, the 4 extracted factors have significant impact on the dependent variable with relatively high significant alpha value of p< 0.000, per the multiple regression output , corresponding to relatively positive unstandardized coefficients. This implies that, the explanatory variables are prominent determinants with strong evidence to reject the null hypothesis at 95% critical value. However, the Adjusted Square R2 indicates a significant relationship between Efficiency and the explanatory variables at 50.3%. The study concluded that, the public sector needs substantial empirical evidence to enlighten the real impact of key institutional drivers of efficiency and a conventional standard for measuring efficiency.
El aporte del gobierno corporativo en las soluciones de los problemas actuales de la empresa moderna
Authors: Tabra Edison Paul
Published: March 2018

El presente artículo argumenta desde una perspectiva multidisciplinar la conveniencia de que las empresas implementen mecanismos de gobierno corporativo para mejorar su imagen o reputación corporativa y, además, superar los problemas que la empresa trae consigo en la actualidad. Asimismo, el presente trabajo propone las principales teorías que desarrollan el gobierno corporativo y propone algunas pautas de aplicación.
Indicadores de impacto en la investigación científica
Authors: Díaz Corrales Alba Veranay , Pedroza Pacheco Manuel Enrique
Published: March 2018

Dada la importancia del componente investigación para dar respuesta a fenómenos y problemas que demanda la sociedad, en la Universidad Nacional de Ingeniería (UNI) dentro de las formas de culminación de estudios a nivel de pregrado y posgrado, se encuentra el trabajo monográfico para la obtención del título profesional de Ingeniero o Arquitecto. Por lo antes expuesto es necesario evaluar la pertinencia y aporte de la UNI a la sociedad a través del impacto de las investigaciones desarrolladas. En vista que, la investigación es una estrategia de búsqueda del conocimiento, así como fuente de innovación y aprendizaje constante de la realidad, se constituye en factor clave para la transformación tecnológica y educativa de la sociedad. Es propósito de este ensayo, es explorar los términos conceptuales relacionados con los indicadores de impacto y la investigación, que permitan evaluar su eficacia.
Cyber threats to children and youth with intellectual disabilities
Authors: Zieliński Sebastian
Published: March 2018

The article provides the justification for the need to analyze the area of 'new media' with regard to the use of digital tools by children and youth with intellectual disabilities. It presents the genesis of the notion of cyberspace as well as the nature of possible consequences associated with inappropriate use of digital technologies. The paper then discusses the categories of negative effects related to cyberspace and the use of new technologies by children and youth with intellectual disabilities. The increasing digitization has influenced the evolution of cyberbullying. There is no highly effective method or solution available to protect children and youth with intellectual disabilities against cyber crimes. Therefore, the idea of reasonable usage of 'new media' seems to be one of the most important tasks for educators, teachers, and parents of children and youth with intellectual disabilities in the 21st century.
Pesquisa Operacional aplicada à Administração: um estudo sobre os artigos internacionais publicados entre 1993 e 2013
Authors: Santos Wellington Furtado , Simonetto Eugenio De Oliveira , Ferreira David Luiz Silva
Published: March 2018

This study examines the international scientific literature in operations research applied to management, published between the years 1993 - 2013. Regarding the results of the last years there has been an increase of 1500% in the number of articles published in this area. The largest share of published articles belongs to the European continent with 46.36% of the publications in the last 20 years. The supply chain with 9.6% is the topic that attracts interest in publishing articles. The relevance can be verified by its index h = 21, this period 176 articles were published in international operations research applied to management.
Boas práticas em gestão de projetos: um estudo na prefeitura de Praia Grande
Authors: Kameiya Marcelo Yoshinori , Romeiro Maria Do Carmo , Kniess Claudia Terezinha
Published: March 2018

Project management in the public sector has assumed new content, aimed at transforming the management practices in intelligence model for implementation of strategies, from which emerged the interest in expanding the studies at the municipal level. The goal was to identify the project management practices, according to the standard of good practice PMBoK. The methodological procedures involves an exploratory stage with data collection with municipal secretaries, which contributed to the expansion of knowledge about management practices and hence for structuring the questionnaire later answered by self-administered for 60 managers. Data analysis used the basic statistical analysis, enough to reach the goal, the result revealed that the management scope, integration and acquisitions are on the upper level of adherence to best practices, as cost, quality, schedule and communications level and lower risks and human resources for more critical level.
Phylogeography of Swertia perennis in Europe based on cpDNA markers
Authors: Urbaniak Jacek , Kwiatkowski Paweł , Pawlikowski Paweł
Published: March 2018

Abstract

Background. Swertia perennis (Gentianaceae) is a perennial diploid and clonal plant species found discontinuously distributed in the peat bogs in mountains of Europe, Asia and North America as well as in European lowlands. The current geographical dispersion of S. perennis is probably an effect of Quaternary climatic changes that played an important role in determining the present-day distribution of Swertia and numerous other plant and animal species.

Methods. A presented survey of molecular studies based on combined data from chloroplast DNA markers (trnL-trnF and trnH-psbA) that were conducted to elucidate the phylogeography of S. perennis in European localities. Plants were collected from 28 populations that represent different localities in lowlands as well as in mountain areas of Europe (Carpathians, Sudetes, Bohemian Forest and Alps). The cDNA sequences were statistically analysed according to phylogenetical relationships in between specimens collected in separate localities.

Results. During the study, 20 haplotypes were characterized representing a high level of genetic variability, but showing a lack of phylogeographical structure. This pattern can be a result of repeated recolonization and expansion from several areas. Such genetic differentiation may also have been due to the relatively long-term isolation of S. perennis in Pleistocene refugia in Europe, resulting in independent separation of different cpDNA phylogenetic lineages.

Discussion. The lack of phylogeographical structure makes it impossible to indicate the centre of haplotype diversity, but refugia located between the ice sheets in the lowlands, Carpathians, Sudetes or the Alps are the most probable sites, where S. perennis existed in Europe. The lack of evidence for phylogeographic structure possibly indicates a high level of gene flow in the recent. The variation in nucleotide composition of cpDNA may reflect the genetic variability from the ancient period, when the landscape and the fen systems were not fragmented, especially on the lowlands, however, at present, it is difficult to speculate about relations between northern and mountain parts of its distribution range in Europe.
The neuronal migration hypothesis of dyslexia: a critical evaluation thirty years on
Authors: Guidi Luiz G , Velayos-Baeza Antonio , Martinez-Garay Isabel , Monaco Anthony P , Paracchini Silvia , Bishop Dorothy V M , Molnar Zoltan
Published: March 2018

The capacity for language is one of the key features underlying the complexity of human cognition and its evolution. However, little is known about the neurobiological mechanisms that mediate normal or impaired linguistic ability. For developmental dyslexia, early post-mortem studies conducted in the 1980s linked the disorder to subtle defects in the migration of neurons in the developing neocortex. These early studies were reinforced by human genetic analyses that identified dyslexia susceptibility genes and subsequent evidence of their involvement in neuronal migration. In this review, we examine recent experimental evidence that does not support the link between dyslexia and neuronal migration. We critically evaluate gene function studies conducted in rodent models and draw attention to the lack of robust evidence from histopathological and imaging studies in humans. Our review suggests that the neuronal migration hypothesis of dyslexia should be reconsidered, and the anatomical and genetic basis of dyslexia should be approached with a fresh start.
Improving long-term coral reef monitoring in the Wider Caribbean region: Global Coral Reef Monitoring Network - Caribbean accomplishments
Authors: Labbouz Lucie , Pena Maria
Published: March 2018

Long-term, robust coral reef monitoring coupled with strategic reporting are essential drivers for ecosystem-based management and regional policy processes. Since the restructuring of the Caribbean component of the Global Coral Reef Monitoring Network (GCRMN) in August 2014, the GCRMN-Caribbean has been bolstering its presence and regional acknowledgement as a dynamic network. An expert steering committee and members-at-large have enabled the network to achieve substantial progress. GCRMN-Caribbean bio-physical guidelines have been improved and tested at several sites; communication and experience sharing have increased considerably; capacity building actions have been implemented for coral reef practitioners with a special focus on MPA managers; and there has been collaboration with major Caribbean programmes. This paper reports on the progress of the GCRMN-Caribbean in 2017: the development of socio-economic guidelines for an integrated monitoring approach, the implementation of building capacity projects “for coral reef and human dimensions monitoring within the Wider Caribbean", within a workshop-based training program to increase regional capacity for integrated bio-physical and socio-economic monitoring. Besides its achievements for the year, this paper also reports on GCRMN-Caribbean network challenges and next steps, including development of a standardized data analysis and reporting in 2018 and participation in the International Year of the Reef.
Dominance across montane meadows: Patterns and processes structuring plant communities
Authors: LaPlante Erika , Souza Lara
Published: March 2018

Background. Understanding the underlying factors that determine the relative abundance of plant species is critical to predict both biodiversity and ecosystem function. Biotic and abiotic factors can shape the distribution and the relative abundance of species across natural communities, greatly influencing local biodiversity.

Methods. Using a combination of an observational study and a five-year plant removal experiment we: (1) documented how plant diversity and composition of montane meadow assemblages vary along a plant dominance gradient using an observational study; (2) tracked above- and belowground functional traits of co-dominant plant species Potentilla and Festuca along a plant dominance gradient in an observational study; (3) determined whether plant species diversity and composition was directly influenced by commonly occurring species Potentilla and Festuca with the use of a randomized plot design, 5-year plant removal experiment (no removal control, Potentilla removed, Festuca removed, n=10) .

Results. We found that subordinate species diversity and compositional dissimilarity were greatest in Potentilla and Festuca co-dominated sites, where neither Potentilla nor Festuca dominated, rather than at sites where either species became dominant. Further, while above- and belowground plant functional traits varied along a dominance gradient, they did so in a way that inconsistently predicted plant species relative abundance. Also, neither variation in plant functional traits of Festuca and Potentilla nor variation in resources and conditions (such as soil nitrogen and temperature) explained our subordinate diversity patterns. Finally, neither Potentilla nor Festuca influenced subordinate diversity or composition when we directly tested for their impacts in a plant removal experiment.

Discussion. Taken together, patterns of subordinate diversity and composition were likely driven by abiotic factors rather than biotic interactions. As a result, the role of abiotic factors influencing local-level species interactions can be just as important as biotic interactions themselves in structuring plant communities.
Early fall and late winter diets of migratory caribou in northwest Alaska
Authors: Joly Kyle , Cameron Matthew D.
Published: March 2018

Lichens are the primary winter forage for large herds of migratory caribou (Rangifer tarandus). Caribou select for lichens more than they are available across the landscape and they generally avoid, during winter, habitat that has been burned by wildfires for decades while lichen abundance recovers. However, the relative importance of lichens in the diet is subject to debate. From 2010-2013, we conducted one of the largest microhistological studies of the early fall (58 samples from 1 site) and late winter (338 samples from 58 sites) diets of barren-ground caribou. Lichens con­stituted ~ 71% of the late winter diets of caribou in northwest Alaska, whereas moss (11%) and shrubs (9%) were the next most common forage items. Early fall diets were very similar to late winter, perhaps because deciduous vegetation is senescent during both periods. Diets of males, non-pregnant females and pregnant females were not significantly different. Pregnancy was not associated with the abundance of any forage type during winter but was associated with higher physiological stress. This result was expected as fall body condition dictates conception, caribou are ‘capital’ breeders, and gestation can be energetically demanding. Caribou that migrated south (i.e., wintered south of 67.1°N) had lower levels of nutritional stress, higher levels of lichen in the diet, and lower levels of moss and shrubs compared to caribou that did not migrate south. Future investigations into the potential connection between lichen abundance in the winter diet and survivorship, as well as linking the late summer diets of individuals to their reproductive success, should be undertaken.
Tri-band MIMO Antenna for WLAN, WiMAX and Defence System & Radio Astronomy Applications
Authors: Babu K. B. V. , Anuradha B.
Published: March 2018

In this paper, an efficacious and impermeable undeviating MIMO consist of 70 x 50 x 0.4 mm3 is used for WLAN, defence system & radio astronomy and WiMAX applications. To keep in order abandoning the reactive connection between the antennas, a neutralizing line is connected between the two symmetrical radiating elements. Another technique to reducing isolation (mutual coupling) between the antennas, four small slits of small size are etched onto to the ground plane. This has resulted in the proposed antenna giving a good bandwidth at the three resonant frequencies of (3.2–3.7 GHz) for Wireless LAN, (5.1–5.6 GHz) WiMAX and (6.7–7.5 GHz) defence system & radio astronomy applications with |S11|< -10 dB and mutual coupling |S12|< -20 dB for the entire operating band. The simulation results and measured results demonstrate that tri-band MIMO antenna is more acceptable for the design in portable device applications.
Compact Uniplanar Multi Feed Multi Band ACS Monopole Antenna Loaded With Multiple Radiating Branches for Portable Wireless Devices
Authors: Vummadisetty P. N. , Kumar A.
Published: March 2018

This research article presents, a compact 0.19 λ x 0.32 λ size ACS fed printed monopole wideband antenna loaded with multiple radiating branches suitable for LTE2300/WiBro, 5 GHz WLAN and WiMAX applications. The proposed triple band uniplanar antenna encompasses of C shaped strip, L shaped strip, rectangular shaped strip and a lateral ground plane. All the radiating strips and ground plane are etched on the 26 × 15 m size low cost FR4 epoxy substrate. This designed geometry evoked three independent reonances at 2.3 GHz, 3.5 GHz and 5.5 GHz with precise impedance matching over each operating band. The reflection coefficient ( ) response of the presented antenna demonstrates three distinct resonant modes associated with -10 dB bandwidths are about 2.24-2.40 GHz, 3.38-3.83 GHz and 5.0-6.25 GHz respectively. From the study, it is also observed that the proposed design works perfect with microstrip as well as CPW feedings. Hence the designed Multi Feed Multi Band (MFMB) antenna can be easily deployed in to any portable wireless device that works for 2.3/3.5/ 5 GHz frequency bands.
Sundaland Peat Carbon Dynamics and Its Contribution to the Holocene Atmospheric CO2 Concentration
Authors: Abrams Jesse F. , Hohn Sönke , Rixen Tim , Merico Agostino
Published: March 2018

The Sunda Shelf is a large submerged extension of the continental shelf of mainland Asia, joining the islands of Borneo, Java, and Sumatra and forming the shallow seabed of the South China Sea. Recent studies identified present‐day peatlands in Southeast Asia as a globally important carbon reservoir. However, little is known about Sundaland paleopeatlands and their role in the global carbon cycle since the Last Glacial Maximum. Using a topography‐based, sea level‐driven model, we estimate the potential spatial extent of peatlands during the late Pleistocene and early Holocene across the low‐lying Sundaland plains. We then use the estimated peatland area together with data on carbon accumulation rates to calculate the total peat carbon pool on the Sunda Shelf. Finally, using a global biogeochemical model, we analyze the relative influence of the predicted Sundaland peat dynamics and other carbon change mechanisms, specifically high‐latitude forest growth and peat formation, shallow sea carbonate deposition, ocean warming, and combinations of them, on the global carbon cycle of the Holocene. We identify a feedback mechanism between sea level and peatland carbon sequestration in Sundaland that reduced atmospheric CO2 concentration by about 4–5 ppm and increased δ13C by 0.05‰ during the Holocene. We also show that a concurrence of mechanisms that includes Sundaland peat dynamics produces model results that are consistent with proxy records, especially with respect to δ13C.
Limitations on Limitation
Authors: Laakso Thomas A. , Schrag Daniel P.
Published: March 2018

Phosphorus is believed to be the globally limiting nutrient in the modern ocean, but a number of nutrients have been invoked as limiting the Proterozoic biosphere. Mass balance calculations suggest that Proterozoic net primary productivity must have been 1 to 2 orders of magnitude less than today in order to maintain low oxygen levels despite increased burial efficiency in anoxic environments. The resulting demand for nutrients is so low that nitrogen, molybdenum, and iron could not have limited the rate of primary production following the evolution of extant nitrogenases. Phosphorus demand was approximately equal to the modern riverine flux, making phosphorus the most likely candidate for the limiting nutrient throughout the Proterozoic.
Model‐Data Fusion to Test Hypothesized Drivers of Lake Carbon Cycling Reveals Importance of Physical Controls
Authors: Hararuk Oleksandra , Zwart Jacob A. , Jones Stuart E. , Prairie Yves , Solomon Christopher T.
Published: March 2018

Formal integration of models and data to test hypotheses about the processes controlling carbon dynamics in lakes is rare, despite the importance of lakes in the carbon cycle. We built a suite of models (n = 102) representing different hypotheses about lake carbon processing, fit these models to data from a north‐temperate lake using data assimilation, and identified which processes were essential for adequately describing the observations. The hypotheses that we tested concerned organic matter lability and its variability through time, temperature dependence of biological decay, photooxidation, microbial dynamics, and vertical transport of water via hypolimnetic entrainment and inflowing density currents. The data included epilimnetic and hypolimnetic CO2 and dissolved organic carbon, hydrologic fluxes, carbon loads, gross primary production, temperature, and light conditions at high frequency for one calibration and one validation year. The best models explained 76–81% and 64–67% of the variability in observed epilimnetic CO2 and dissolved organic carbon content in the validation data. Accurately describing C dynamics required accounting for hypolimnetic entrainment and inflowing density currents, in addition to accounting for biological transformations. In contrast, neither photooxidation nor variable organic matter lability improved model performance. The temperature dependence of biological decay (Q10) was estimated at 1.45, significantly lower than the commonly assumed Q10 of 2. By confronting multiple models of lake C dynamics with observations, we identified processes essential for describing C dynamics in a temperate lake at daily to annual scales, while also providing a methodological roadmap for using data assimilation to further improve understanding of lake C cycling.
Weakening Relationship Between Vegetation Growth Over the Tibetan Plateau and Large‐Scale Climate Variability
Authors: Shi Fangzhong , Wu Xiuchen , Li Xiaoyan , Chen Deliang , Liu Hongyan , Liu Shaomin , Hu Xia , He Bin , Shi Chunming , Wang Pei , Mao Rui , Ma Yujun , Huang Yongmei
Published: March 2018

Vegetation growth on the Tibetan Plateau is strongly affected by large‐scale climate variability, particularly the Pacific Decadal Oscillation (PDO) and the North Atlantic Oscillation (NAO). However, potential temporal changes in both the direction and strength of relationships between regional vegetation growth and large‐scale climate variability remain poorly understood. Here we quantify temporal changes in these relationships during 1982–2012, using satellite‐derived normalized difference vegetation index, global ecosystem model simulations of net primary productivity, regional tree ring chronologies, and PDO and NAO indexes. We found consistent weakening relationships between mean growing‐season (April–October) normalized difference vegetation index and both PDO and NAO. A similar pattern was also found in the temporal relationship between net primary productivity and PDO. Such weakening relationships were partly attributable to weakening regional summer atmospheric circulation and its causal effects on changes in hydrothermal conditions over the Tibetan Plateau. These findings highlight a varying coupling of regional vegetation growth to large‐scale climate variability at the interannual/decadal scale during past decades, and this feature should be considered in future prediction of terrestrial vegetation growth in response to shifting climate regime.
Long‐Term Stimulatory Warming Effect on Soil Heterotrophic Respiration in a Cool‐Temperate Broad‐Leaved Deciduous Forest in Northern Japan
Authors: Teramoto Munemasa , Liang Naishen , Ishida Sachinobu , Zeng Jiye
Published: March 2018

To evaluate the long‐term response of soil organic carbon decomposition to global warming in Asian monsoon forests, we established a multichannel automated chamber system combined with infrared carbon‐filament heat lamps in a 70‐year‐old cool‐temperate broad‐leaved deciduous forest in northern Japan in September 2011. We designed control plots to measure total soil respiration (Rs), root exclusion (trenched) plots to measure heterotrophic respiration (Rh), and warmed trenched plots to measure Rh under warmed conditions (+2.5°C soil temperature at 5 cm depth, Rhw). Annual effluxes ranged from 12.02 to 14.15 tC ha−1 in Rs, 7.78 to 11.49 tC ha−1 in Rh, and 8.76 to 15.25 tC ha−1 in Rhw over five years (2012–2016). During the summer season (between July and September), the daily warming effect was negatively related to soil temperature. In comparison, the relationship between soil moisture and the daily warming effect varied in each year depending on soil moisture levels. The annual warming effect exhibited large interannual variation, ranging from 6.2 to 17.7% °C−1; however, the five year average (10.9% °C−1) was close to the estimated value (10.2% °C−1) based on the annual Q10 of Rh (2.66). Interannual variation was positively related to the number of rainy days (p = 0.013). Our results indicate that existing global terrestrial models underestimate the strength of the feedback of Rh to global warming in Asian monsoon forests, because most global terrestrial models used relatively low Q10 values (usually below 2.0).
Illustrated instructions for mechanical quality assurance of a medical linear accelerator
Authors: Court Laurence , Wang He , Aten David , Brown Derek , MacGregor Hannelie , du Toit Monique , Chi Melinda , Gao Song , Yock Adam , Aristophanous Michalis , Balter Peter
Published: March 2018

Purpose

The purpose of this study was to develop and test a set of illustrated instructions for effective training for mechanical quality assurance (QA) of medical linear accelerators (linac).

Methods

Illustrated instructions were created for mechanical QA and underwent several steps of review, testing, and refinement. Eleven testers with no recent QA experience were then recruited from our radiotherapy department (one student, two computational scientists, and eight dosimetrists). This group was selected because they have experience of radiation therapy but no preconceived ideas about how to do QA. The following parameters were progressively decalibrated on a Varian C‐series linac: Group A = gantry angle, ceiling laser position, X1 jaw position, couch longitudinal position, physical graticule position (five testers); Group B = Group A + wall laser position, couch lateral and vertical position, collimator angle (three testers); Group C = Group B + couch angle, wall laser angle, and optical distance indicator (three testers). Testers were taught how to use the linac and then used the instructions to try to identify these errors. An experienced physicist observed each session, giving support on machine operation as necessary.

Results

Testers were able to follow the instructions. They determined gantry, collimator, and couch angle errors within 0.4°, 0.3°, and 0.9° of the actual changed values, respectively. Laser positions were determined within 1 mm and jaw positions within 2 mm. Couch position errors were determined within 2 mm and 3 mm for lateral/longitudinal and vertical errors, respectively. Accessory‐positioning errors were determined within 1 mm. Optical distance indicator errors were determined within 2 mm when comparing with distance sticks and 6 mm when using blocks, indicating that distance sticks should be the preferred approach for inexperienced staff.

Conclusions

Inexperienced users were able to follow these instructions and catch errors within the criteria suggested by AAPM TG‐142 for linacs used for intensity‐modulated radiation therapy. These instructions are, therefore, suitable for QA training.
Normal tissue doses from MV image‐guided radiation therapy (IGRT) using orthogonal MV and MV‐CBCT
Authors: Li Yuting , Netherton Tucker , Nitsch Paige L. , Balter Peter A. , Gao Song , Klopp Ann H. , Court Laurence E.
Published: March 2018

Purpose

The aim of this study was to measure and compare the mega‐voltage imaging dose from the Halcyon medical linear accelerator (Varian Medical Systems) with measured imaging doses with the dose calculated by Eclipse treatment planning system.

Methods

An anthropomorphic thorax phantom was imaged using all imaging techniques available with the Halcyon linac — MV cone‐beam computed tomography (MV‐CBCT) and orthogonal anterior‐posterior/lateral pairs (MV‐MV), both with high‐quality and low‐dose modes. In total, 54 imaging technique, isocenter position, and field size combinations were evaluated. The imaging doses delivered to 11 points in the phantom (in‐target and extra‐target) were measured using an ion chamber, and compared with the imaging doses calculated using Eclipse.

Results

For high‐quality MV‐MV mode, the mean extra‐target doses delivered to the heart, left lung, right lung and spine were 1.18, 1.64, 0.80, and 1.11 cGy per fraction, respectively. The corresponding mean in‐target doses were 3.36, 3.72, 2.61, and 2.69 cGy per fraction, respectively. For MV‐MV technique, the extra‐target imaging dose had greater variation and dependency on imaging field size than did the in‐target dose. Compared to MV‐MV technique, the imaging dose from MV‐CBCT was less sensitive to the location of the organ relative to the treatment field. For high‐quality MV‐CBCT mode, the mean imaging doses to the heart, left lung, right lung, and spine were 8.45, 7.16, 7.19, and 6.51 cGy per fraction, respectively. For both MV‐MV and MV‐CBCT techniques, the low‐dose mode resulted in an imaging dose about half of that in high‐quality mode.

Conclusion

The in‐target doses due to MV imaging using the Halcyon ranged from 0.59 to 9.75 cGy, depending on the choice of imaging technique. Extra‐target doses from MV‐MV technique ranged from 0 to 2.54 cGy. The MV imaging dose was accurately calculated by Eclipse, with maximum differences less than 0.5% of a typical treatment dose (assuming a 60 Gy prescription). Therefore, the cumulative imaging and treatment plan dose distribution can be expected to accurately reflect the actual dose.
Black‐Phosphorus‐Incorporated Hydrogel as a Sprayable and Biodegradable Photothermal Platform for Postsurgical Treatment of Cancer
Authors: Shao Jundong , Ruan Changshun , Xie Hanhan , Li Zhibin , Wang Huaiyu , Chu Paul K. , Yu Xue‐Feng
Published: March 2018

Photothermal therapy (PTT) is a fledgling therapeutic strategy for cancer treatment with minimal invasiveness but clinical adoption has been stifled by concerns such as insufficient biodegradability of the PTT agents and lack of an efficient delivery system. Here, black phosphorus (BP) nanosheets are incorporated with a thermosensitive hydrogel [poly(d,l‐lactide)‐poly(ethylene glycol)‐poly(d,l‐lactide) (PDLLA‐PEG‐PDLLA: PLEL)] to produce a new PTT system for postoperative treatment of cancer. The BP@PLEL hydrogel exhibits excellent near infrared (NIR) photothermal performance and a rapid NIR‐induced sol–gel transition as well as good biodegradability and biocompatibility in vitro and in vivo. Based on these merits, an in vivo PTT postoperative treatment strategy is established. Under NIR irradiation, the sprayed BP@PLEL hydrogel enables rapid gelation forming a gelled membrane on wounds and offers high PTT efficacy to eliminate residual tumor tissues after tumor removal surgery. Furthermore, the good photothermal antibacterial performance prevents infection and this efficient and biodegradable PTT system is very promising in postoperative treatment of cancer.
Low‐Temperature Combustion Synthesis of a Spinel NiCo2O4 Hole Transport Layer for Perovskite Photovoltaics
Authors: Papadas Ioannis T. , Ioakeimidis Apostolos , Armatas Gerasimos S. , Choulis Stelios A.
Published: March 2018

The synthesis and characterization of low‐temperature solution‐processable monodispersed nickel cobaltite (NiCo2O4) nanoparticles (NPs) via a combustion synthesis is reported using tartaric acid as fuel and the performance as a hole transport layer (HTL) for perovskite solar cells (PVSCs) is demonstrated. NiCo2O4 is a p‐type semiconductor consisting of environmentally friendly, abundant elements and higher conductivity compared to NiO. It is shown that the combustion synthesis of spinel NiCo2O4 using tartaric acid as fuel can be used to control the NPs size and provide smooth, compact, and homogeneous functional HTLs processed by blade coating. Study of PVSCs with different NiCo2O4 thickness as HTL reveals a difference on hole extraction efficiency, and for 15 nm, optimized thickness enhanced hole carrier collection is achieved. As a result, p‐i‐n structure of PVSCs with 15 nm NiCo2O4 HTLs shows reliable performance and power conversion efficiency values in the range of 15.5% with negligible hysteresis.
Learning from the past: Are catalyst design principles transferrable between hydrodesulfurization and deoxygenation?
Authors: Kasiraju Sashank , Grabow Lars C.
Published: March 2018

Molybdenum‐oxide (MoO3) is a promising catalyst candidate for hydrodeoxygenation (HDO) of pyrolysis vapor or liquefaction products to renewable fuels or value‐added chemicals. Density functional theory is used to study the mechanism and active site requirements for HDO of furan over the MoO3(010) facet and contrast our results with prior work on hydrodesulfurization (HDS) of thiophene over MoS2 model catalysts. The potential energy diagram for HDO over a realistically terminated MoO3(010) surface facet reveals that the elementary reaction steps for deoxygenation are facile, but the formation of oxygen‐vacancies is slow and endothermic. In general, HDO over MoO3 and HDS over MoS2 exhibit mechanistic similarities, which suggests that knowledge transfer from the mature HDS system to the emerging field of HDO catalysis is possible. For example, transition metal promotion of MoO3 resulted in an improvement of the kinetics and thermodynamics of oxygen vacancy formation, similar to Co and Ni promotion of MoS2. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3121–3133, 2018
Analysis of volume‐to‐surface ratio effects on methane oxidative coupling using microkinetic modeling
Authors: Alexiadis V. I. , Serres T. , Marin G. B. , Mirodatos C. , Thybaut J. W. , Schuurman Y.
Published: March 2018

The effect of the volume‐to‐surface (V/S) ratio on the catalytic performance of a La–Sr/CaO catalyst in a fixed bed reactor under oxidative coupling of methane (OCM) conditions is investigated by adjusting the amount of diluent in the catalyst bed. It was observed experimentally that the catalyst activity, C2 selectivity, and C2H4/C2H6 ratio are all favored at high V/S ratios. The total void volume, available in the intraparticle and the interstitial phase, was considered. A comprehensive OCM microkinetic model, explicitly distinguishing between these two phases, allowed accounting for the observed dependence of catalytic performance on V/S ratio. The major experimentally implemented variation in interstitial volume available for reaction, provoked also changes in radical concentration profiles in intraparticle phase. Given the high reaction rates occurring at this location, the experimentally observed effects with varying the V/S ratio, are attributed to concentration and, hence, reaction rate changes occurring mainly in the intraparticle phase. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2603–2611, 2018
Residual level of dimethachlon in rice‐paddy field system and cooked rice determined by gas chromatography with electron capture detector
Authors: Sun Caiyuan , Zeng Lingrong , Xu Jin , Zhong Lei , Han Xinwen , Chen Lingzhu , Zhang Yuping , Hu Deyu
Published: March 2018

In this study, a modified quick, easy, cheap, effective, rugged and safe method coupled with gas chromatography with electron capture detection was established to determine dimethachlon residues in paddy soil, rice husk, rice straw, brown rice and cooked rice. The limits of quantification of dimethachlon were 0.01 mg/kg for paddy soil, brown rice and cooked rice and 0.02 mg/kg for rice straw and rice husk. The mean recoveries were in the range 78.59–104.7% with relative standard deviation values of <10% for dimethachlon in the five matrices. For field experiments, the final residues of dimethachlon in paddy soil were < 0.05 mg/kg and were < 1.21 mg/kg in rice straw from six sites. The final residues of dimethachlon in the brown rice at 21, 28 and 35 days after spraying from six sites were 0.08–7.58 mg/kg, and 0.16–30.1 mg/kg in rice husk. Our six test sites covered the main rice–producing areas of China. The routine rice cooking process of a Chinese family could apparently increase the removal of dimethachlon in rice compared with brown rice, and the reduction ratios were > 96%.
Enantioseparation and determination of dufulin enantiomers in cucumber and soil by chiral liquid chromatography–tandem mass spectrometry
Authors: Zhang Haizhen , Huang Min , Yu Weiwei , Zhang A'wei , Zhang Kankan , Hu Deyu
Published: March 2018

A simple and rapid method for enantioselective determination of dufulin in cucumber and soil was developed by liquid chromatography with tandem mass spectrometry. The enantiomers were separated on a Superchiral S‐OD chiral cellulose tris(3,5‐dimethylphenylcarbamate) column at 20°C, with a mixture of acetonitrile and water (0.1% formic acid; 52:48, v/v) as mobile phase at a flow rate of 0.65 mL/min. The pretreatment conditions were optimized using an orthogonal test, and the optimized method showed good linearity and sensitivity. The limits of detection and limits of quantification of two dufulin enantiomers were 0.006 and 0.02 mg/kg, respectively. The average recoveries of S‐enantiomer and R‐enantiomer in cucumber and soil were 80.61–99.83% and 80.97–102.96%, respectively, with relative standard deviations of 1.30–9.72%. The method was successfully applied to determine dufulin in real cucumber and soil samples. The results demonstrate that the method could facilitate further research on the differences between individual dufulin enantiomers with respect to metabolites and environmental fate and finally help reveal the complex interactions that exist between dufulin, humans and the environment.
Simultaneous determination of three flavonoids and one coumarin by LC–MS/MS: Application to a comparative pharmacokinetic study in normal and arthritic rats after oral administration of Daphne genkwa extract
Authors: Zhou Luyi , Li Jing , Yan Chong
Published: March 2018

A selective and sensitive liquid chromatography–tandem mass spectrometry method was developed and validated for investigating the pharmacokinetics of umbelliferone, apigenin, genkwanin and hydroxygenkwanin after oral administration of Daphne genkwa extract. Plasma samples were treated by protein precipitation with acetonitrile. Analytes were detected by triple‐quadrupole MS/MS with an ESI source in negative selection reaction monitoring mode. The transitions of m/z 161 → 133 for umbelliferone, m/z 269 → 117 for apigenin, m/z 283 → 268 for genkwanin and m/z 299 → 284 for hydroxygenkwanin were confirmed for quantification. Chromatographic separation was conducted using an Eclipse XDB‐C18 column, and the applied isocratic elution program allowed for simultaneous determination of the four analytes for a total run time of 2.5 min. The linearity was validated over the plasma concentration ranges of 1.421–1421 ng/mL for umbelliferone, 0.845–845 ng/mL for apigenin, 1.025–1025 ng/mL for genkwanin and 0.845–845 ng/mL for hydroxygenkwanin. The extraction recovery rate was >82.7% for each analyte. No apparent matrix effect was observed during the bioanalysis. After full validation, the proposed method was successfully applied to compare the pharmacokinetics of these analytes between normal and arthritic rats.