bluuebunny/crossref_metadata_2025 huggingface dataset:
Identifying the origin and geochemical evolution of groundwater using hydrochemistry and stable isotopes in the Subei Lake basin, Ordos energy base, Northwestern China
Authors: Liu F. , Song X. , Yang L. , Zhang Y. , Han D. , Ma Y. , Bu H.
Published: January 2015

Abstract. A series of changes in groundwater systems caused by groundwater exploitation in energy base have been of great concern to hydrogeologists. The research aims to identify the origin and geochemical evolution of groundwater in the Subei Lake basin under the influence of human activities. Water samples were collected, and major ions and stable isotopes (δ18O, δD) were analyzed. In terms of hydrogeological conditions and the analytical results of hydrochemical data, groundwater can be classified into three types: the Quaternary groundwater, the shallow Cretaceous groundwater and the deep Cretaceous groundwater. Piper diagram and correlation analysis were used to reveal the hydrochemical characteristics of water resources. The dominant water type of the lake water was Cl-Na type, which was in accordance with hydrochemical characteristics of inland salt lakes; the predominant hydrochemical types for groundwater were HCO3–Ca, HCO3–Na and mixed HCO3–Ca–Na–Mg types. The groundwater chemistry is mainly controlled by dissolution/precipitation of anhydrite, gypsum, halite and calcite. The dedolomitization and cation exchange are also important factors. Rock weathering is confirmed to play a leading role in the mechanisms responsible for the chemical composition of groundwater. The stable isotopic values of oxygen and hydrogen in groundwater are close to the local meteoric water line, indicating that groundwater is of modern local meteoric origin. Unlike significant differences in isotopic values between shallow groundwater and deep groundwater in the Habor Lake basin, shallow Cretaceous groundwater and deep Cretaceous groundwater have similar isotopic characteristics in the Subei Lake basin. Due to the evaporation effect and dry climatic conditions, heavy isotopes are more enriched in lake water than in groundwater. The low slope of the regression line of δ18O and δD in lake water could be ascribed to a combination of mixing and evaporation under conditions of low humidity. Comparison of the regression line for δ18O and δD showed that lake water in the Subei Lake basin contains more heavily isotopic composition than that in the Habor Lake basin, indicating that lake water in the discharge area has undergone stronger evaporation than lake water in the recharge area. Hydrochemical and isotopic information of utmost importance has been provided to decision makers by the present study so that a sustainable groundwater management strategy can be designed for the Ordos energy base.
Coupled local facilitation and global hydrologic inhibition drive landscape geometry in a patterned peatland
Authors: Acharya S. , Kaplan D. A. , Casey S. , Cohen M. J. , Jawitz J. W.
Published: January 2015

Abstract. Self-organized landscape patterning can arise in response to multiple processes. Discriminating among alternative patterning mechanisms, particularly where experimental manipulations are untenable, requires process-based models. Previous modeling studies have attributed patterning in the Everglades (Florida, USA) to sediment redistribution and anisotropic soil hydraulic properties. In this work, we tested an alternate theory, the self-organizing canal (SOC) hypothesis, by developing a cellular automata model that simulates pattern evolution via local positive feedbacks (i.e., facilitation) coupled with a global negative feedback based on hydrology. The model is forced by global hydroperiod that drives stochastic transitions between two patch types: ridge (higher elevation) and slough (lower elevation). We evaluated model performance using multiple criteria based on six statistical and geostatistical properties observed in reference portions of the Everglades landscape: patch density, patch anisotropy, semivariogram ranges, power-law scaling of ridge areas, perimeter area fractal dimension, and characteristic pattern wavelength. Model results showed strong statistical agreement with reference landscapes, but only when anisotropically acting local facilitation was coupled with hydrologic global feedback, for which several plausible mechanisms exist. Critically, the model correctly generated fractal landscapes that had no characteristic pattern wavelength, supporting the invocation of global rather than scale-specific negative feedbacks.
Using high frequency water quality data to assess sampling strategies for the EU Water Framework Directive
Authors: Skeffington R. A. , Halliday S. J. , Wade A. J. , Bowes M. J. , Loewenthal M.
Published: January 2015

Abstract. The EU Water Framework Directive (WFD) requires that the ecological and chemical status of water bodies in Europe should be assessed, and action taken where possible to ensure that at least "good" quality is attained in each case by 2015. This paper is concerned with the accuracy and precision with which chemical status in rivers can be measured given certain sampling strategies, and how this can be improved. High frequency (hourly) chemical data from four rivers in southern England were subsampled to simulate different sampling strategies for four parameters used for WFD classification: dissolved phosphorus, dissolved oxygen, pH and water temperature. These data sub-sets were then used to calculate the WFD classification for each site. Monthly sampling was less precise than weekly sampling, but the effect on WFD classification depended on the closeness of the range of concentrations to the class boundaries. In some cases, monthly sampling for a year could result in the same water body being assigned to one of 3 or 4 WFD classes with 95% confidence, whereas with weekly sampling this was 1 or 2 classes for the same cases. In the most extreme case, random sampling effects could result in the same water body being assigned to any of the 5 WFD quality classes. The width of the weekly sampled confidence intervals was about 33% that of the monthly for P species and pH, about 50% for dissolved oxygen, and about 67% for water temperature. For water temperature, which is assessed as the 98th percentile in the UK, monthly sampling biases the mean downwards by about 1 °C compared to the true value, due to problems of assessing high percentiles with limited data. Confining sampling to the working week compared to all seven days made little difference, but a modest improvement in precision could be obtained by sampling at the same time of day within a 3 h time window, and this is recommended. For parameters with a strong diel variation, such as dissolved oxygen, the value obtained, and thus possibly the WFD classification, can depend markedly on when in the cycle the sample was taken. Specifying this in the sampling regime would be a straightforward way to improve precision, but there needs to be agreement about how best to characterise risk in different types of river. These results suggest that in some cases it will be difficult to assign accurate WFD chemical classes or to detect likely trends using current sampling regimes, even for these largely groundwater-fed rivers. A more critical approach to sampling is needed to ensure that management actions are appropriate and supported by data.
Brief Communication: The use of an unmanned aerial vehicle in a rockfall emergency scenario
Authors: Giordan D. , Manconi A. , Facello A. , Baldo M. , dell'Anese F. , Allasia P. , Dutto F.
Published: January 2015

Abstract. In recent years, the use of unmanned aerial vehicles (UAVs) in civilian/commercial contexts are becoming increasingly common, as well as for applications concerning anthropic and natural disasters. In this paper, we present the first results of a research project aimed at defining a possible methodology for the use of micro-UAVs in emergency scenarios relevant to rockfall phenomena. To develop and support the method presented herein, the results relevant to a rockfall emergency occurred on 7 March 2014 in the San Germano municipality (north-western Italy) are presented and discussed.
A method for predicting the factor of safety of an infinite slope based on the depth ratio of the wetting front
Authors: Chae B.-G. , Lee J.-H. , Park H.-J. , Choi J.
Published: January 2015

Abstract. Most landslides in Korea are classified as shallow landslides with an average depth of less than 2 m. These shallow landslides are associated with the advance of a wetting front in the unsaturated soil due to rainfall infiltration, which results in an increase in water content and a reduction in the matric suction in the soil. Therefore, this study presents a modified equation of infinite slope stability analysis based on the concept of the saturation depth ratio to analyze the slope stability change associated with the rainfall on a slope. A rainfall infiltration test in unsaturated soil was performed using a column to develop an understanding of the effect of the saturation depth ratio following rainfall infiltration. The results indicated that the rainfall infiltration velocity due to the increase in rainfall in the soil layer was faster when the rainfall intensity increased. In addition, the rainfall infiltration velocity tends to decrease with increases in the unit weight of soil. The proposed model was applied to assess its feasibility and to develop a regional landslide susceptibility map using a Geographic Information System (GIS). For that purpose, the spatial databases for input parameters were constructed and landslide locations were obtained. In order to validate the proposed approach, the results of the proposed approach were compared with the landslide inventory using ROC (Receiver Operating Characteristics) graph. In addition, the results of the proposed approach were compared with the previous approach used steady state hydrological model. Consequently, the approach proposed in this study displayed satisfactory performance in classifying landslide susceptibility and showed better performance than the steady state approach.
Measuring air–sea gas-exchange velocities in a large-scale annular wind–wave tank
Authors: Mesarchaki E. , Kräuter C. , Krall K. E. , Bopp M. , Helleis F. , Williams J. , Jähne B.
Published: January 2015

Abstract. In this study we present gas-exchange measurements conducted in a large-scale wind–wave tank. Fourteen chemical species spanning a wide range of solubility (dimensionless solubility, α = 0.4 to 5470) and diffusivity (Schmidt number in water, Scw = 594 to 1194) were examined under various turbulent (u10 = 0.73 to 13.2 m s−1) conditions. Additional experiments were performed under different surfactant modulated (two different concentration levels of Triton X-100) surface states. This paper details the complete methodology, experimental procedure and instrumentation used to derive the total transfer velocity for all examined tracers. The results presented here demonstrate the efficacy of the proposed method, and the derived gas-exchange velocities are shown to be comparable to previous investigations. The gas transfer behaviour is exemplified by contrasting two species at the two solubility extremes, namely nitrous oxide (N2O) and methanol (CH3OH). Interestingly, a strong transfer velocity reduction (up to a factor of 3) was observed for the relatively insoluble N2O under a surfactant covered water surface. In contrast, the surfactant effect for CH3OH, the high solubility tracer, was significantly weaker.
Observing Muostakh disappear: permafrost thaw subsidence and erosion of a ground-ice-rich island in response to arctic summer warming and sea ice reduction
Authors: Günther F. , Overduin P. P. , Yakshina I. A. , Opel T. , Baranskaya A. V. , Grigoriev M. N.
Published: January 2015

Abstract. Observations of coastline retreat using contemporary very high resolution satellite and historical aerial imagery were compared to measurements of open water fraction, summer air temperature, and wind. We analysed seasonal and interannual variations of thawing-induced cliff top retreat (thermo-denudation) and marine abrasion (thermo-abrasion) on Muostakh Island in the southern central Laptev Sea. Geomorphometric analysis revealed that total ground ice content on Muostakh is made up of equal amounts of intrasedimentary and macro ground ice and sums up to 87%, rendering the island particularly susceptible to erosion along the coast, resulting in land loss. Based on topographic reference measurements during field campaigns, we generated digital elevation models using stereophotogrammetry, in order to block-adjust and orthorectify aerial photographs from 1951 and GeoEye, QuickBird, WorldView-1, and WorldView-2 imagery from 2010 to 2013 for change detection. Using sea ice concentration data from the Special Sensor Microwave Imager (SSM/I) and air temperature time series from nearby Tiksi, we calculated the seasonal duration available for thermo-abrasion, expressed as open water days, and for thermo-denudation, based on the number of days with positive mean daily temperatures. Seasonal dynamics of cliff top retreat revealed rapid thermo-denudation rates of −10.2 ± 4.5 m a−1 in mid-summer and thermo-abrasion rates along the coastline of −3.4 ± 2.7 m a−1 on average during the 2010–2013 observation period, currently almost twice as rapid as the mean rate of −1.8 ± 1.3 m a−1 since 1951. Our results showed a close relationship between mean summer air temperature and coastal thermo-erosion rates, in agreement with observations made for various permafrost coastlines different to the East Siberian Ice Complex coasts elsewhere in the Arctic. Seasonality of coastline retreat and interannual variations of environmental factors suggest that an increasing length of thermo-denudation and thermo-abrasion process simultaneity favours greater coastal erosion. Coastal thermo-erosion has reduced the island's area by 0.9 km2 (24%) over the past 62 years but shrank its volume by 28 x 106 m3 (40%), not least because of permafrost thaw subsidence, with the most pronounced with rates of ≥− 11 cm a−1 on yedoma uplands near the island's rapidly eroding northern cape. Recent acceleration in both will halve Muostakh Island's lifetime to less than a century.
Modeling of crack propagation in weak snowpack layers using the discrete element method
Authors: Gaume J. , van Herwijnen A. , Chambon G. , Schweizer J. , Birkeland K. W.
Published: January 2015

Abstract. Dry-snow slab avalanches are generally caused by a sequence of fracture processes including (1) failure initiation in a weak snow layer underlying a cohesive slab, (2) crack propagation within the weak layer and (3) tensile fracture through the slab which leads to its detachment. During the past decades, theoretical and experimental work has gradually led to a better understanding of the fracture process in snow involving the collapse of the structure in the weak layer during fracture. This now allows us to better model failure initiation and the onset of crack propagation, i.e. to estimate the critical length required for crack propagation. On the other hand, our understanding of dynamic crack propagation and fracture arrest propensity is still very limited. For instance, it is not uncommon to perform field measurements with widespread crack propagation on one day, while a few days later, with very little changes to the snowpack, crack propagation does not occur anymore. Thus far, there is no clear theoretical framework to interpret such observations, and it is not clear how and which snowpack properties affect dynamic crack propagation. To shed more light on this issue, we performed numerical propagation saw test (PST) experiments applying the discrete element (DE) method and compared the numerical results with field measurements based on particle tracking. The goal is to investigate the influence of weak layer failure and the mechanical properties of the slab on crack propagation and fracture arrest propensity. Crack propagation speeds and distances before fracture arrest were derived from the DE simulations for different snowpack configurations and mechanical properties. Then, the relation between mechanical parameters of the snowpack was taken into account so as to compare numerical and experimental results, which were in good agreement, suggesting that the simulations can reproduce crack propagation in PSTs. Finally, an in-depth analysis of the mechanical processes at play was carried out which led to suggestions for minimum column length in field PSTs.
Controlled Retrieval of Specific Context Information in Children and Adults
Authors: REIMER JASON F. , ARMENDAREZ JOSEPH J.
Published: January 2015

This study adapted a procedure used by Luo and Craik (2009) to examine whether developmental differences exist in the ability to use controlled retrieval processes to access the contextual details of memory representations. Participants from 3 age groups (mean ages 9, 12, and 25 years) were presented with words in 3 study contexts: with a black-and-white picture, with a color picture, or alone without a picture. Six recognition tests were then presented that varied in the demands (high or low) placed on the retrieval of specific contextual information. Each test consisted of a mixture of words that were old targets from 1 study context, distractors (i.e., previously studied words from a different context), and completely new words. A high-specificity and a low-specificity test list was paired with each test question, with high and low specificity being determined by the nature of the distractors used in a test list. High-specificity tests contained words that were studied in similar contexts: old targets (e.g., words studied with black-and-white pictures) and distractors (e.g., words studied with color pictures). In contrast, low-specificity tests contained words that were studied in dissimilar contexts: old targets (e.g., words studied with black-and-white pictures) and distractors (e.g., words previously studied without a picture). Relative to low-specificity tests, the retrieval conditions of high-specificity tests were assumed to place greater demands on the controlled access of specific contextual information. Analysis of recollection scores revealed that age differences were present on highbut not low-specificity tests, with the performance of 9-year-olds disproportionately affected by the retrieval demands of high-specificity tests.
When Do We Use Automatic Tools Rather Than Doing a Task Manually? Influence of Automatic Tool Speed
Authors: NAVARRO JORDAN , OSIURAK FRANÇOIS
Published: January 2015

In our everyday lives we tend to minimize effort, by using automatic tools, for instance. But we also tend to avoid idleness by engaging in various activities. What happens when minimizing effort and avoiding idleness are concurrent? This article explores the influence of waiting time as compared with a fixed manual task completion on people’s preference for waiting or doing the task. In 2 experiments, participants were asked to choose performing a manual task or waiting while an automatic tool performed the task for them. The time required by the automatic tool to complete the task was manipulated and was equal to or shorter than the time needed for manual completion. Results indicated that the faster the automatic tool (i.e., the shorter the waiting time) the more participants used it instead of doing the task manually. However, participants favored the waiting option only when the waiting time was less than half as long as doing the task manually. These results suggest that people prefer to avoid idleness rather than to minimize effort.
Orientação de Estágio: uma experiência na formação de docentes
Authors: Rocha Karla Marques da , Abegg Ilse , Rela Eliana
Published: January 2015

Este artigo aborda a utilização das Tecnologias Educacionais em Rede, especialmente o recurso Wiki, na disciplina de Supervisão de Estágio em um Programa Especial de Graduação de Formação de Professores para a Educação Profissional e Tecnológica, em uma universidade pública brasileira. Analisou-se os registros feitos por vinte e nove estudantes e o respectivo orientador, referentes aos planos de Aula e sua implementação como parte do processo da avaliação das competências do planejar e do refletir. As postagens geraram reflexões no espaço Wiki, proporcionando categorias de elementos indicadores para a supervisão dos futuros estágios, na forma de rede de conversação. A possibilidade de acompanhamentos, orientações, avaliações e aprendizagens tornou-se efetivamente um período de construção de experiências, além do espaço acadêmico.
O método como conteúdo: o ensino de história com fontes patrimoniais
Authors: Nascimento Evandro Cardoso do
Published: January 2015

Este artigo apresenta resultados de uma pesquisa realizada com alunos da 3ª série do ensino médio de um colégio de Matinhos/PR em 2013. Partindo da concepção proposta por Zaragoza (1989) que a inserção do método histórico como conteúdo é fator indispensável a uma aprendizagem histórica significativa, optou-se por utilizar fontes patrimoniais em sala de aula objetivando o desenvolvimento da consciência histórica dos alunos (RÜSEN, 2001). A metodologia de ensino foi a Aula Oficina (BARCA, 2004) em que o professor é caracterizado como o organizador das atividades problematizadoras e os alunos agentes de sua própria formação. Os resultados acendem um método para a utilização de fontes primárias no ensino onde o patrimônio é posto em evidência.
O Ensino de Filosofia como “questão clássica” na tradição do pensamento filosófico
Authors: Ceppas Filipe
Published: January 2015

Neste artigo, procuro mostrar que ensinar e aprender filosofia são questões centrais e recorrentes para a tradição filosófica Ocidental. Procuro argumentar em favor desta tese em duas direções. Num primeiro momento, ela é analisada em termos da relação entre o pensar, o juízo e o ensino-aprendizado da filosofia. Num segundo momento, procuro defender esta tese a partir da importância da relação mestre-discípulo para a história da filosofia.
Práticas de ensino e formação docente: notas sobre a experiência da Licenciatura em Filosofia da UFABC
Authors: Pereira Marinê De Souza , Velasco Patrícia Del Nero
Published: January 2015

O presente artigo tem como objetivo refletir sobre a concepção de prática de ensino como experiência de formação docente. Para tanto, inicia com uma série de questionamentos sobre a Filosofia como disciplina escolar; na sequência, aborda a ideia de prática como componente curricular, discutindo algumas de suas possíveis interpretações; por fim, apresenta a proposta do Curso de Licenciatura em Filosofia da Universidade Federal do ABC, analisando em que medida os cinco módulos de práticas de ensino do referido curso pretendem se constituir em espaços de experiência formativa de professores, conciliando as reflexões sobre o Ensino de Filosofia com as problematizações que caracterizam o filosofar.
Da História da Filosofia ao Filosofar: alguns desafios no diálogo com o não filosófico
Authors: Tomazetti Elisete Medianeira , Benetti Cláudia Cisiane
Published: January 2015

Este texto propõe uma reflexão sobre um modo de ensinar e aprender filosofia que se consolidou nos cursos superiores de filosofia e produziu efeitos diferenciados em ensino na escola básica. Destaca os discursos produzidos, nas últimas décadas, no tensionamento entre ensinar filosofia e ensinar a filosofar perpassados pela relação com a História da Filosofia e, tendo como referência as Diretrizes Curriculares Nacionais do Ensino Médio (2012), apresenta um novo cenário escolar em construção. Em tal cenário está indicado um novo desenho curricular, estruturado por área de conhecimentos, que passa a solicitar dos professores o enfrentamento da questão da interdisciplinaridade e da contextualização dos saberes escolares. Nessas condições, procuramos pensar, de forma inicial, sobre o ensino de filosofia, no contexto da área das Ciências Humanas, com vistas a experiências interdisciplinares.
Increased carotid atherosclerosis and carotid artery stiffness according to the disease duration and activity in patients with systemic lupus erythematosus
Authors: Byun Gi Sup , Lee Ji Hyun , Cho Kyoung Im , Lee HongJik , Yeo Hyun Jung , Kim Min Jeong , Im Ho Joon
Published: January 2015

Objective: The ᅵink among carotid intimamedia thickness (IMT), vascular elastic property and the disease activity of systemic lupus erythematosus (SLE) is not well defined. We investigated the association between carotid atherosclerosis, elastic properties of the carotid arterial wall and clinical parameters of SLE. Methods: Fifty-one SLE patients and fifty healthy controls were included. Peak systolic global circumferential and posterior radial strains of carotid artery were measured to assess the elastic properties. Beta stiffness index was used as conventional method for the distensibility of the carotid artery. Information concerning SLE duration, cumulative dose of steroids and/or immunosuppressive drug intake was recorded, and SLE activity was assessed by SLE disease activity index (SLEDAI) score. Results: Carotid plaques were more common in SLE patients. SLE patients with plaques were 㢌der and showed the increased mean ᅵMT, high sensitivity C-reactive protein (hs CRP), IgG anti-cardi㢌ipin antibody (aCL), and longer disease duration compared with those without plaques. Peaksyst㢌ic global circumferential and posterior radial strain as well β stiffness index were significantly lower in SLE group. Age, disease duration, hsCRP, IgG aCL showed significant correlations with mean ᅵMT and parameters of carotid elastic property (all P's<0.05). Conclusions: Carotid atherosclerosis was more common in SLE patients, and carotid arterial stiffness had significant correlation with disease duration, hsCRP and IgG aCL level. Speckle tracking strain imaging is a comparative method for the assessment of elastic properties of carotid artery of SLE patients.
Pathological differences between forceps biopsy specimens and endoscopic resection specimens in early gastric cancer patients
Authors: Kim Joo Seok , Kim Sae Hee , Kim Min Gyu , Ryu Ah Jeong , Ryu Il Hwan , Lee Jae Jun , Jeon Jae Woong , Choi Ji Wook , Kim Anna
Published: January 2015

Objective: Endoscopic resection(ER) is effective therapy on EGC and which is treated according to the histological diagnosis of forcep biopsy. But sometimes the histological diagnosis of forcep biopsy and post-ER does not match with each other and it might lead to wrong treatment. The aim of this study is to find the frequency of histologic differences between forcep biopsy and post-ER, and to confirm the characteristics of lesions which make errors. Methods: We selected the confirmed cancer cases of 141 patients of 1359 gastric tumor lesions which were treated under the ER in Eulji university hospital from May 2005 to March 2013. They were sorted by the age and sex of patient, location of lesion, present of ulcer and depression to identify the discordance between forcep biopsy and ER. The discordant group was compared with non-cancer-diagnosed controlled group, retrospectively. Results: 70 cases(5.5%) of 1283 cases of “cancer negative” in forceps biopsy were fo䴸nd to be diagnosed cancer on final diagnosis of cancer by post-ER result. In this discordant group showed characteristics of bigger size that are with more frequently in tumor size D15mm(17.9% vs. 31.4%, p=0.03), have depressed lesion(ᄀ 4.3% vs. 41.4%, p<0.01) and have 䴸lceration(2.4% vs.18.6%, p<0.01) than that of 84 control gro䴸p not diagnosed cancer. Conclusions: In cases of tumor with size D15mm, presented with depressed lesion and ulceration, we should consider combined cancer, even the result of forcep biopsy was negative. Therefore, more careful and accurate resection should be taken with characters listed above.
Gender Differences in Risk Factor and Clinical Outcome in Patients with Ischemic Stroke
Authors: Kim Kwang Soo
Published: January 2015

Objective: Gender is an important determinant for risk factors and outcomes of ischemic stroke. The aim of this study was to compare risk factors, and clinical outcomes after ischemic stroke between male and female patients. Methods: The hospital records of patients with ischemic stroke were reviewed retrospectively. Demographic data, stroke risk factors, clinical severities and outcomes after stroke were collected and compared between male and female patients. Stroke severity and clinical disability after ischemic stroke were evaluated by means of the National Institutes of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS) respectively. Results: Among 447 patients with ischemic stroke, 195 (43.6%) patients were women. The mean age at ischemic stroke was higher in women than in men (p<0.01). As compared to men, women had a significantly lower prevalence of hyperhomocysteinemia, smoking and drinking (all p<0.01). NIHSS and mRS scores were not different between the 2 genders. Conclusions: Profiles of risk factors differed between the 2 genders, with men having a higher prevalence of hyperhomocysteinemia, smoking and drinking. There were no gender differences in stroke severity and disability after ischemic stroke.
A Case of Ischemic Colitis Related with Usual Dosage of Ibuprofen in a Young Man
Authors: Kim Eun Jeong , Park Moo In , Park Seun Ja , Moon Won , Yeo Go Eun , Lee Weon Hyoung
Published: January 2015

Abstract Ischemic colitis is a medical condition in which inflammation and injury of the large intestine result from inadequate blood supply. Although unoommon in the general p㢌pulation, ischemic colitis occurs with greater frequency in the elderly, and is the most common form of bowel ischemia. Other possible causes include medications s䴸ch as NSAIDs(non-steroidal antiinflammatory drugs), oral contraceptives, diuretics and others. In recent years, many of NSAID use in young age can cause ischemic lesions, but it is not common. Here we report a case of ischemic colitis in a 31-year-old man who had no specific medical history except taking 200mg of ibuprofen three times a day for seven days. It suggests the importance of precise history taking, including medications usage such as NSAIDs and other risk factors.
A Case with Empty Sella Syndrome Combined with Multiple Anterior Pituitary Hormone Deficiencies Presenting as Hypoglycemic Coma
Authors: Kim Soo Kyoung , Kim Sung Su , Kim Bo Ra , Jung Jung Hwa , Jung Jae Hoon , Hahm Jong Ryeal
Published: January 2015

Abstract A 55-year-old male was admitted to emergency department with a hypoglycemic shock of unknown origin. He was presented with tonic seizure activity after admission. Initial diagnostic procedure could exclude diabetes mellitus, drug side effects, and exogenous insulin application. Detailed evaluation of the patient's history revealed that the patient had experienced repeated hypoglycemic episodes for 2 years. He was diagnosed with hypothyroidism six years ago. Initial laboratory investigations revealed hypoglycemia, hyponatremia, and low plasma cortisol level (0.18 pg/dᄂ)· Sellar magnetic resonance imaging showed empty sella. Replacement therapy with hydrocortisone resulted in the improvement of clinical symptoms. Combined pituitary stimulation test with exception of hypoglycemia induced growth hormone and cortisol stimulation test was performed. The response of thyroid stimulating hormone, prolactin, follicle-stimulating hormone, and luteinizing hormone was normal. We report the case of empty sella syndrome associated with hypoglycemic shock due to with multiple anterior pituitary hormone deficiencies.
A Case of Reactivation of Hepatitis B and Fulminant Hepatitis which developed 3 months following Chemotherapy Including Rituximab in a Patient with Lymphoma
Authors: Lim Tae Won , Oh Hee Taek , Song Seung Un , Lee Hae Won , Kim Ji Yeon , Park Seon Ja
Published: January 2015

Abstract Since Wands et al. reported for the first time in 1975 the reactivation of the hepatitis B virus in hematologic disease patients who had been receiving chemotherapy, the efficacy of chemotherapy and immunosuppressants has improved. As a result, the frequency of the reactivation of hepatitis B is increasing. Reported herein is a case of a non-Hodgkin lymphoma patient in her 70s who was suspected to have had HBsAg negative/anti-HBs negative occult HBV infection. The patient experienced fulminant hepatitis caused by the reactivation of hepatitis B, and died three months after the R-CHOP regimen was completed. In the HBsAg negative plus HBV DNA-negative case, there were few instances of viral activation of HBV. In this case, antiviral therapy was needed when the patient was confirmed to have become HBV DNA positive through regular monitoring, but its necessity is often overlooked, unlike the preemptive antiviral treatment in the HBsAg positive cases.
Vektör gözlemleri ile küçük uydularda yönelim belirleme yöntemleri
Authors: ÇİLDEN Demet , HACIZADE Cengiz
Published: January 2015

Özet

Uzay teknolojisinde yaşanan gelişmeler ile birlikte küçük uyduların uzay görevlerinde kullanılma sıklığındaki artış, bu uyduların yönelim belirleme yöntemleri konusunda yapılan bilimsel çalışmaların artmasını da beraberinde getirmiştir. Kütle ve boyutlarının küçük olmasının yanında ucuz olmaları da alt sistemlerinin ayrı ayrı test edilebilmesi ve hatta ilerleyen teknolojinin getirisiyle üretilebilecek tüm alt sistemlerin çeşitli uzay görevlerinde daha sık kullanılması için önemli bir parametre durumundadır.

Bu çalışmada, Wahba’nın hata fonksiyonunu minimuma indirmek amaçlı kullanılan yöntemlerden bazıları iki vektör kullanılarak kıyaslanmıştır. Bu iki vektör, güneş ile manyetik alan vektörleri, sensör verileri ve oluşturulmuş modeller sonucunda elde edilmiştir. Bu yöntemlerin, tekillik sorunu olmaksızın çözüm üretebilmesi için hesaplarda kuvaterniyonlar kullanılmış, sonucunda ise hata hesabı yapması amaçlanmıştır. Kullanılan metodlar hız ve doğruluk açısından karşılaştırıldığı gibi anlık hata analizi de burada önemli bir parametre olmaktadır. Böylece yöntemler arası geçiş anları dahi belirlenebilmektedir. Teknolojinin gelişme göstermesi bilgisayar ortamında yapılan işlem hızları arasındaki farkı küçültse de bu farklılıkları gözetmek uzay ortamında gerekli olacak anlık değişimleri algılama yetisine sahip olmayı da sağlar. Dayanıklılığın önemli olduğu bu çalışmada, simülasyonlar da bunu açıkça ortaya koymuş ve kabul edilebilir bir yönelim tahmini yapılmıştır.
ATMOSFERİK GEÇİŞ YAPAN ARAÇ ETRAFINDA NAVIER-STOKES DENKLEMLERİ İLE ÜÇ BOYUTLU HİPERSONİK AKIŞ ANALİZİ
Authors: ÖZGÜN Muharrem , EYİ Sinan
Published: January 2015

ÖZET

Bu çalışmada hipersonik akışlar için kullanılabilecek isabetli ve etkin bir hesaplamalı akışkanlar dinamiği kodu geliştirilmesi amaçlanmaktadır. Akış analizi üç boyutlu Navier-Stokes denklemlerini temel almaktadır. Bu denklemler Newton metoduyla çözülmekte ve Jacobian matrislerini hesaplamak için analitik metot kullanılmaktadır. Model olarak alınan AS-202 Apollo uzay aracı geometrisi üzerinde akış parametreleri ve taşınımla ısı transferi analiz edilecektir. Ayrıca nümerik olarak stabil olan ve genelde hipersonik akış uygulamalarında iyi tahminler sağlayan Spalart-Allmaras türbülans modeli kullanılarak hipersonik akış için türbülanslı akış analizi yapılacaktır.
Comparison of Pre and Post LASIK Corneal Thickness by Orbscan, Anterior Segment Optical Coherence Tomography, Specular Microscopy, Ultrasonic Pachymetry
Authors: Rajput Metu , Tandon Charu , Sridhar Uma
Published: January 2015

Background :

To measure corneal thickness by Orbscan, Anterior Segment Optical Coherence Tomography, Specular microscopy, Ultrasonic pachymetry Pre and Post LASIK and to compare the four techniques.

Materials and Methods:

A prospective study was conducted at a tertiary care eye hospital to compare corneal thickness by orbscan, anterior segment optical coherence tomography, specular microscopy, ultrasonic pachymetry pre and post LASIK in 50 subjects (100 eyes).

Results:

Baseline mean CCT measured with ORBSCAN was 556.73 ± 17.07, with ULTPACH was 544.13 ± 16.94, with SPEC was 544.55 ± 18.98 and with ASOCT was 544.61 ± 16.39. There was statistically significant difference in mean CCT among orbscan and the other three methods (P <0.001) preoperatively. On postoperative day 7, mean CCT measured with ORBSCAN was 456.60 ± 30.41, with ULTPACH was 475.02 ± 22.26, with SPEC was 472.06 ± 22.99, and with ASOCT was 475.75 ± 24.17. There was statistically significant difference in mean CCT among orbscan, and the other three techniques namely, ultrasonic pachymetry, specular microscopy, anterior segment optical coherence tomography on postoperative day 7 (p <0.001). On postoperative day 30, mean CCT measured with ORBSCAN was 459.32 ± 27.40, with ULTPACH was 480.95 ± 24.88, with SPEC was 475.31 ± 23.20, and with ASOCT was 479.12 ± 23.83. This also showed statistically significant difference in mean CCT between orbscan, and the other three methods.(P <0.001).

Conclusion:

Ultrasonic pachymetry is considered as the gold standard method of measuring CCT and it compares favourably with specular microscopy and AS OCT. Orbscan has a tendency to overestimate pre LASIK and underestimate post LASIK.
Idiopathic Hypertrophic Cranial Pachymeningitis Presenting as Recurrent Multiple Cranial Nerve Palsies: Case Report and Review of Literature
Authors: Sachdeva V , Gupta N , Mittal V , Chandrasekharan A , Kekunnaya R , Suresh T
Published: January 2015

Recurrent ophthalmoplegia poses a diagnostic challenge. A less commonly reported etiology is Idiopathic hypertrophic cranial pachymeningitis (IHCP), characterized by thickening of the dura mater and widespread CNS dysfunction depending of the location. The diagnosis is one of exclusion. Patients have a recurrent course and need immunosuppression. The authors’ report here in diagnostic and management dilemma in a patient with IHCP
Along‐axis variation in crustal thickness at the ultraslow spreading Southwest Indian Ridge (50°E) from a wide‐angle seismic experiment
Authors: Niu Xiongwei , Ruan Aiguo , Li Jiabiao , Minshull T. A. , Sauter Daniel , Wu Zhenli , Qiu Xuelin , Zhao Minghui , Chen Y. John , Singh Satish
Published: January 2015

The Southwest Indian Ridge (SWIR) is characterized by an ultraslow spreading rate, thin crust, and extensive outcrops of serpentinized peridotite. Previous studies have used geochemical and geophysical data to suggest the presence of a thicker crust at the central and shallowest portions of the SWIR, from the Prince Edward (35°30′E) to the Gallieni (52°20′E) fracture zones. Here we present a new analysis of wide‐angle seismic data along the ridge 49°17′E–50°49′E. Our main conclusions are as follows: (1) we find an oceanic layer 2 of roughly constant thickness and steep velocity gradient, underlain by a layer 3 with variable thickness and low velocity gradient; (2) the crustal thickness varies from ∼5 km beneath nontransform discontinuities (NTDs) up to ∼10 km beneath a segment center; (3) the melt supply is focused in segment centers despite a small NTD between adjacent segments; (4) the presence of a normal upper mantle velocity indicates that no serpentinization occurs beneath this thick crust. Our observation of thick crust at an ultraslow spreading ridge adds further complexity to relationships between crustal thickness and spreading rate, and supports previous suggestions that the extent of mantle melting is not a simple function of spreading rate, and that mantle temperature or chemistry (or both) must vary significantly along axis.
Long‐term inverse modeling of Asian dust: Interannual variations of its emission, transport, deposition, and radiative forcing
Authors: Yumimoto Keiya , Takemura Toshihiko
Published: January 2015

Inverse modeling of Asian dust over the 8 year period 2005–2012 was performed with the Spectral Radiation‐Transport Model for Aerosol Species/four‐dimensional variational (SPRINTARS/4D‐Var) data assimilation system and satellite‐measured aerosol optical thickness over the ocean. We validated the inversion results with independent measurements provided by ground‐based and space‐based lidar and various in situ measurements. The inversion results were used to analyze interannual variations of Asian dust fluxes and relationships of these fluxes with climate indices. Dust emissions from central China and the Mongolian Plateau were 229–384 Tg yr−1. The standard deviation of 55.3 Tg yr−1 reflected large interannual variability. The frequency of dust storms and the beginning of the dust season in the source region also showed interannual variations. There was a meridional shift of the outflow path from the continent; the transport core was centered at 40–45°N during southern transport years (2006–2007) and at 35–40°N during northern transport years (2005 and 2008–2012). The fact that dust deposition showed a significant positive correlation with satellite‐measured chlorophyll concentrations indicated that settled Asian dust enhanced phytoplankton blooms in the eastern North Pacific. Dust emissions were positively and negatively correlated with the Far Eastern Zonal and Dynamical Normalized Seasonality indices, respectively, the implication being that a strong meridional pressure gradient over the source region and a strong winter monsoon favor dust emission. The fact that the Southern Oscillation Index was positively correlated with dust emission, transport, and deposition suggests that Asian dust is affected by the El Niño–Southern Oscillation cycle and is enhanced during the La Niña phase.
Controls on the large‐scale spatial variations of dune field properties in the barchanoid portion of White Sands dune field, New Mexico
Authors: Pelletier Jon D.
Published: January 2015

Previous studies have shown that sediment fluxes and dune sizes are a maximum near the upwind margin of the White Sands dune field and decrease, to first order, with increasing distance downwind. These patterns have alternatively been attributed to a shear‐stress overshoot associated with a roughness transition localized at the upwind margin and to the influence of long‐wavelength topography on the hydrology and hence erodibility of dune field sediments. I point out an issue that compromises the shear‐stress overshoot model and further test the hypothesis that long‐wavelength topographic variations, acting in concert with feedbacks among aerodynamic, granulometric, and geomorphic variables, control dune field properties at White Sands. Building upon the existing literature, I document that the mean and variability of grain sizes, sand dryness, aerodynamic roughness lengths, bed shear stresses, sediment fluxes, and ripple and dune heights all achieve local maxima at the crests of the two most prominent scarps in the dune field, one coincident with the upwind margin and the other located 6–7 km downwind. Computational fluid dynamics (CFD) modeling predicts that bed shear stresses, erosion rates, and the supply of relatively coarse, poorly sorted sediments are localized at the two scarps due to flow line convergence, hydrology, and the spatially distributed adjustment of the boundary layer to variations in dune size. As a result, the crests of the scarps have larger ripples due to the granulometric control of ripple size. Larger grain sizes and/or larger ripples lead to larger dunes and hence larger values of bed shear stress in a positive feedback.
The role of local‐scale heterogeneities in terrestrial ecosystem modeling
Authors: Pappas Christoforos , Fatichi Simone , Rimkus Stefan , Burlando Paolo , Huber Markus O.
Published: January 2015

The coarse‐grained spatial representation of many terrestrial ecosystem models hampers the importance of local‐scale heterogeneities. To address this issue, we combine a range of observations (forest inventories, eddy flux tower data, and remote sensing products) and modeling approaches with contrasting degrees of abstraction. The following models are selected: (i) Lund‐Potsdam‐Jena (LPJ), a well‐established, area‐based, dynamic global vegetation model (DGVM); (ii) LPJ‐General Ecosystem Simulator, a hybrid, individual‐based approach that additionally considers plant population dynamics in greater detail; and (iii) distributed in space‐LPJ, a spatially explicit version of LPJ, operating at a fine spatial resolution (100 m × 100 m), which uses an enhanced hydrological representation accounting for lateral connectivity of surface and subsurface water fluxes. By comparing model simulations with a multivariate data set available at the catchment scale, we argue that (i) local environmental and topographic attributes that are often ignored or crudely represented in DGVM applications exert a strong control on terrestrial ecosystem response; (ii) the assumption of steady state vegetation and soil carbon pools at the beginning of simulation studies (e.g., under “current conditions”), as embedded in many DGVM applications, is in contradiction with the current state of many forests that are often out of equilibrium; and (iii) model evaluation against vegetation carbon fluxes does not imply an accurate simulation of vegetation carbon stocks. Having gained insights about the magnitude of aggregation‐induced biases due to smoothing of spatial variability at the catchment scale, we discuss the implications of our findings with respect to the global‐scale modeling studies of carbon cycle and we illustrate alternative ways forward.
Nutrient uptake dynamics across a gradient of nutrient concentrations and ratios at the landscape scale
Authors: Gibson Catherine A. , O'Reilly Catherine M. , Conine Andrea L. , Lipshutz Sondra M.
Published: January 2015

Understanding interactions between nutrient cycles is essential for recognizing and remediating human impacts on water quality, yet multielemental approaches to studying nutrient cycling in streams are currently rare. Here we utilized a relatively new approach (tracer additions for spiraling curve characterization) to examine uptake dynamics for three essential nutrients across a landscape that varied in absolute and relative nutrient availability. We measured nutrient uptake for soluble reactive phosphorous, ammonium‐nitrogen, and nitrate‐nitrogen in 16 headwater streams in the Catskill Mountains, New York. Across the landscape, ammonium‐nitrogen and soluble reactive phosphorus had shorter uptake lengths and higher uptake velocities than nitrate‐nitrogen. Ammonium‐nitrogen and soluble reactive phosphorus uptake velocities were tightly correlated, and the slope of the relationship did not differ from one, suggesting strong demand for both nutrients despite the high ambient water column dissolved inorganic nitrogen: soluble reactive phosphorus ratios. Ammonium‐nitrogen appeared to be the preferred form of nitrogen despite much higher nitrate‐nitrogen concentrations. The uptake rate of nitrate‐nitrogen was positively correlated with ambient soluble reactive phosphorus concentration and soluble reactive phosphorus areal uptake rate, suggesting that higher soluble reactive phosphorus concentrations alleviate phosphorus limitation and facilitate nitrate‐nitrogen uptake. In addition, these streams retained a large proportion of soluble reactive phosphorus, ammonium‐nitrogen, and nitrate‐nitrogen supplied by the watershed, demonstrating that these streams are important landscape filters for nutrients. Together, these results (1) indicated phosphorus limitation across the landscape but similarly high demand for ammonium‐nitrogen and (2) suggested that nitrate‐nitrogen uptake was influenced by variability in soluble reactive phosphorus availability and preference for ammonium‐nitrogen.