bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterisation of Oxide Coatings Produced on Aluminium by PEO at Different Frequencies of Pulsed Current
Authors: Gebarowski Wojciech , Pietrzyk Stanislaw , Richert Maria
Published: August 2015

The Plasma Electrolytic Oxidation (PEO) is a surface modification process that allows producing protective oxide coatings on light metal alloys. These coatings are characterized by high microhardness and wear resistance. Changes of electrical conditions of alternate current during process, such as duration and frequency of anodic and cathodic pulses, influence on layer growth rate, its microstructure and final properties. In this study aluminium samples were oxidized at different electrical parameters in sodium silicate electrolyte. The growth rates of oxide layers were determined by mass change and thickness measurements. The microstructure of the obtained coatings was investigated by using scanning electron microscope. Additionally, phase compositions of coatings was determined by X-ray diffraction on top surfaces of layers. Generally, shorter duration and higher frequency of anodic pulses provides more uniform structure at lower growth rate. Nevertheless, there are certain ranges of electrical parameters that provide decent uniformity of oxide coatings.
Evaluating the Johanson Theory for Titanium Powder
Authors: Chikosha Silethelwe , Machaka Ronald , Chikwanda Hilda
Published: August 2015

Direct powder rolling (DPR)/roll compaction has been labelled a complex and sample sensitive process. As such the design of the instrument and the determination of the optimal processing conditions for a given feed are very challenging. The challenge is attributed to a wide range of operating parameters and material properties. Several theoretical models can be used to evaluate the interaction of the different parameters and properties and how their changes affect the rolling process. In this study, the Johanson theory was used to determine the rolling parameters of titanium powder. Preliminary results of the nip angle, nip pressures and maximum horizontal pressures of the mill for the powder rolled on a 55mm diameter roll with roll gap sizes of 0.175, 0.15 and 0.05 mm were obtained. The results were found to be acceptable for the nip angle estimation, however improvement on predicting the maximum horizontal pressure is required.
Molecular Dynamics Simulation of Ti and Ni Particles on Ti Substrate in the Cold Gas Dynamic Spray (CGDS) Process
Authors: Malama Terence , Hamweendo Agripa , Botef Ionel
Published: August 2015

This paper presents simulation of molecular dynamics for the deposition of Titanium (Ti) and Nickel (Ni) particles on Ti substrate during Cold Gas Dynamic Spray (CGDS) process. The influencing factors of the deposition process, such as particle incident velocity, particle size and particle temperature are taken into consideration. Ti and Ni were selected because of their potential applications in the aerospace, marine and bio-medical industries. CGDS is preferred because it is a state of the art technique by which coatings are created without significant heating of the sprayed powder. In CGDS, particles are accelerated to supersonic velocities using a high speed gas stream. However, there are inherent difficulties in relating particle deposition characteristics with influencing factors of the deposition process. Moreover, there is limited literature on molecular dynamics simulation of CGDS process. For this reason, this paper develops a simulation process for Ti and Ni particles under influence of many factors using molecular dynamics. In this process, particles are allowed to interact for a short time, giving a view of their motion. The trajectories of these particles are determined by numerically solving the Newton's equations of motion for a system of interacting particles, in which the forces between the particles are defined. The results of the simulation process show that higher incident velocities and larger particle sizes result in stronger interface between the particle and the substrate. Further, higher temperatures of the substrate and particles improve the bond strength.
Simulation of Natural Aging in Al-Mg-Si Alloys
Authors: Weisz Thomas , Warczok Piotr , Ebner Thomas , Falahati Ahmad , Kozeschnik Ernst
Published: August 2015

Natural aging during storage of Al-Mg-Si alloys at room temperature can significantly reduce the maximum strengthening potential (T6) during artificial aging and, therefore, is a key topic in aluminium research and industry. Many different strategies to understand and reduce the negative effect of natural aging have been investigated during the last decades, including analysis of different thermal pre-treatments and considering the effect of different microalloying elements. From these investigations, the vacancy evolution and the formation of clusters containing Mg and Si were found to be the governing aging mechanisms behind natural aging. In this work, we present a model to simulate and predict the behavior of these alloys when subjected to room temperature aging after solutionizing and demonstrate the effects of different thermal routes and chemical composition variations. In the implemented model, the evolution of excess quenched-in vacancies and the effect of solute vacancy traps are considered. Special emphasis is placed on co-cluster formation and its contribution to strengthening. The thermokinetic software MatCalc is used for the simulations and the results of the simulations are validated by experimental investigation.
Investigations on Fire-Resistant Magnesium Alloys for Aerospace Applications
Authors: Gradinger Rudolf , Gneiger Stefan , Betz Andreas
Published: August 2015

Light metals are contributing significantly to the weight saving of components and structures of transport means. Regarding airliners FAA recently published a report on the development of a flammability test for magnesium alloys to be used in aircraft seat construction which opens up the options to introduce specific parts in next seat models. In former projects, it was shown that magnesium alloys are offering interesting mass reduction and-by this-fuel & emissions saving potentials in air transport.
The major concern is the behaviour of Mg alloys in case of an aircraft fire which was investigated by FAA for particular alloys of Magnesium-Neodymium-Gadolinium, Magnesium-Yttrium-Rare Earth as well as Magnesium-Aluminium-Zinc composition in course to the test methods development. While clearly the AZ31 alloy fails in such a laboratory test, the other two types pass flawlessly by exhibiting a self-extinguishing behaviour shortly after removing the fire source. None of them are specifically usable for high pressure die casting or thixomolding processes which both are common production methods. From the typically used thixomolding alloys like AZ91D, AM50A, AM60B or AJ62A, the Magnesium-Aluminium-Zinc again is likely to fail in flammability tests due to the low-temperature melting network of eutectic phase.
Therefore, the development focussed on Magnesium-Aluminium-Manganese and Magnesium-Aluminium-Strontium type alloys. Calcium – well known for the ability to improve the flammability behaviour – was added in certain concentrations to those alloying systems and investigated regarding self-extinguishing performance, manufacturing issues as well as mechanical properties. The results of these examinations are presented in the following paper.
Microstructure and Texture Development during Melt Conditioned Twin Roll Casting and Downstream Processing in an AZ31 Magnesium Alloy
Authors: Huang Yan , Fan Zhong Yun
Published: August 2015

The novel melt conditioned twin roll casting (MCTRC) process, in which the melt is conditioned by intensive shearing prior to twin roll casting, has allowed magnesium sheets to be produced with a fine and uniform microstructure and substantially reduced segregations across the sheet thickness. It is thus possible to eliminate the extensive downstream processing via repetitive hot rolling, which is required after conventional twin roll casting, and to produce sheets to the required thickness for forming. The present work was conducted to study the feasibility of producing magnesium sheets ready for stamping by the MCTRC process, focusing on the development of microstructures and textures. An AZ31 magnesium alloy was used in the investigation and MCTRC experiments were carried out to produce sheets of 6 mm and 2.5 mm in thickness respectively. After MCTRC, the 6 mm sheet was processed following the conventional procedures via homogenization, hot rolling and annealing, whereas the 2.5 sheet was only homogenized. Experimental results showed that: 1) the as-cast microstructures for both sheets were similalr in terms of grain size and distribution and their texture intensity and components were also similar, being dominated by basal components with a small fraction of primatic components; 2) downstream processing by hot rolling substantially intensified the basal textures for the 6 mm sheet; 3) the 2.5 mm sheet subjected only to homogenization after casting showed a grain structure similar to that obtained after repetitive hot rolling and annealing with substantially weakened textures. Mechanisms of texture formation and development during MCTRC and downstream processing are discussed in the paper.
Reducing Non Value Adding Aluminium Alloy in Production of Parts by High Pressure Die Casting Using High Temperature Die Manufacturing Material
Authors: Pereira Filipe , Williams Martin
Published: August 2015

The difficulties and issues associated with the economics of the process and die life in casting aluminium alloys, as experienced by the high pressure die casting industry, were reasons behind undertaking this research project. The use of a tungsten alloy able to withstand high temperature process conditions without the welding problems experienced by standard die construction materials, such as H13, was examined in an extensive series of casting trials. The importance of operating dies at elevated temperatures to minimize heat checking has been demonstrated previously, both through theoretical thermal modelling and experimentation. This paper describes both aspects of die life extension and possibilities to reduce the amount of alloy material used in the cast part feed system, including overflows. CSIR intends using the results of this research for further development and application of high temperature die construction materials in high pressure die casting processes of light metal alloys.
Regulatory and Helper Follicular T Cells and Antibody Avidity to Simian Immunodeficiency Virus Glycoprotein 120
Authors: Blackburn Matthew J. , Zhong-Min Ma , Caccuri Francesca , McKinnon Katherine , Schifanella Luca , Guan Yongjun , Gorini Giacomo , Venzon David , Fenizia Claudio , Binello Nicolò , Gordon Shari N. , Miller Christopher J. , Franchini Genoveffa , Vaccari Monica
Published: August 2015

T follicular regulatory cells (TFR) are a suppressive CD4+ T cell subset that migrates to germinal centers (GC) during Ag presentation by upregulating the chemokine receptor CXCR5. In the GC, TFR control T follicular helper cell (TFH) expansion and modulate the development of high-affinity Ag-specific responses. In this study, we identified and characterized TFR as CXCR5+CCR7− “follicular” T regulatory cells in lymphoid tissues of healthy rhesus macaques, and we studied their dynamics throughout infection in a well-defined animal model of HIV pathogenesis. TFR were infected by SIVmac251 and had comparable levels of SIV DNA to CXCR5−CCR7+ “T zone” T regulatory cells and TFH. Contrary to the SIV-associated TFH expansion in the chronic phase of infection, we observed an apparent reduction of TFR frequency in cell suspension, as well as a decrease of CD3+Foxp3+ cells in the GC of intact lymph nodes. TFR frequency was inversely associated with the percentage of TFH and, interestingly, with the avidity of the Abs that recognize the SIV gp120 envelope protein. Our findings show changes in the TFH/TFR ratio during chronic infection and suggest possible mechanisms for the unchecked expansion of TFH cells in HIV/SIV infection.
The Transcription Factor Ehf Is Involved in TGF-β–Induced Suppression of FcεRI and c-Kit Expression and FcεRI-Mediated Activation in Mast Cells
Authors: Yamazaki Susumu , Nakano Nobuhiro , Honjo Asuka , Hara Mutsuko , Maeda Keiko , Nishiyama Chiharu , Kitaura Jiro , Ohtsuka Yoshikazu , Okumura Ko , Ogawa Hideoki , Shimizu Toshiaki
Published: August 2015

FcεRI, which is composed of α, β, and γ subunits, plays an important role in IgE-mediated allergic responses. TGF-β1 has been reported to suppress FcεRI and stem cell factor receptor c-Kit expression on mast cell surfaces and to suppress mast cell activation induced by cross-linking of FcεRI. However, the molecular mechanism by which these expressions and activation are suppressed by TGF-β1 remains unclear. In this study, we found that the expression of Ets homologous factor (Ehf), a member of the Ets family transcriptional factors, is upregulated by TGF-β/Smad signaling in mouse bone marrow–derived mast cells (BMMCs). Forced expression of Ehf in BMMCs repressed the transcription of genes encoding FcεRIα, FcεRIβ, and c-Kit, resulting in a reduction in cell surface FcεRI and c-Kit expression. Additionally, forced expression of Ehf suppressed FcεRI-mediated degranulation and cytokine production. Ehf inhibited the promoter activity of genes encoding FcεRIα, FcεRIβ, and c-Kit by binding to these gene promoters. Furthermore, the mRNA levels of Gata1, Gata2, and Stat5b were lower in BMMCs stably expressing Ehf compared with control cells. Because GATA-1 and GATA-2 are positive regulators of FcεRI and c-Kit expression, decreased expression of GATAs may be also involved in the reduction of FcεRI and c-Kit expression. Decreased expression of Stat5 may contribute to the suppression of cytokine production by BMMCs. In part, mast cell response to TGF-β1 was mimicked by forced expression of Ehf, suggesting that TGF-β1 suppresses FcεRI and c-Kit expression and suppresses FcεRI-mediated activation through upregulation of Ehf.
Plasmacytoid Dendritic Cell Activation and IFN-α Production Are Prominent Features of Murine Autoimmune Pancreatitis and Human IgG4-Related Autoimmune Pancreatitis
Authors: Arai Yasuyuki , Yamashita Kouhei , Kuriyama Katsutoshi , Shiokawa Masahiro , Kodama Yuzo , Sakurai Toshiharu , Mizugishi Kiyomi , Uchida Kazushige , Kadowaki Norimitsu , Takaori-Kondo Akifumi , Kudo Masatoshi , Okazaki Kazuichi , Strober Warren , Chiba Tsutomu , Watanabe Tomohiro
Published: August 2015

The abnormal immune response accompanying IgG4-related autoimmune pancreatitis (AIP) is presently unclear. In this study, we examined the role of plasmacytoid dendritic cell (pDC) activation and IFN-α production in this disease as well as in a murine model of AIP (MRL/Mp mice treated with polyinosinic-polycytidylic acid). We found that the development of AIP in treated MRL/Mp mice occurred in parallel with pancreatic accumulation of pDCs producing IFN-α, and with pDC depletion and IFN-α-blocking studies, we showed that such accumulation was necessary for AIP induction. In addition, we found that the pancreas of treated MRL/Mp mice contained neutrophil extracellular traps (NETs) shown previously to stimulate pDCs to produce IFN-α. Consistent with these findings, we found that patients with IgG4-related AIP also exhibited pancreatic tissue localization of IFN-α–expressing pDCs and had significantly higher serum IFN-α levels than healthy controls. In addition, the inflamed pancreas of these patients but not controls also contained NETs that were shown to be capable of pDC activation. More importantly, patient pDCs cultured in the presence of NETs produced greatly increased levels of IFN-α and induced control B cells to produce IgG4 (but not IgG1) as compared with control pDCs. These data suggest that pDC activation and production of IFN-α is a major cause of murine AIP; in addition, the increased pDC production of IFN-α and its relation to IgG4 production observed in IgG4-related AIP suggest that this mechanism also plays a role in the human disease.
Geology, geochemistry, and origin of the gold deposits of the Yellowknife District, Northwest Territories
Authors: Boyle R W
Published: August 2015

The geology and mineralogy of the gold-quartz deposits of the Yellowknife district are described together with an exhaustive study of the geochemistry of the country rocks and alteration zones and the geochemistry and origin of the ore and gangue minerals, and
underground waters. The deposits occur as quartz lenses in extensive chlorite schist zones (shear zones) cutting Precambrian greenstones, and as quartz lenses developed along structures in highly folded and contorted Precambrian sedimentary rocks. Those in the greenstones represent concentrations of
silica, carbon dioxide, sulphur, arsenic, antimony, gold, silver and numerous other metallic elements. Those in the sediments are mainly concentrations of silica, sulphur, boron, iron, lead, zinc, gold and silver. Chemical evidence is presented to show that during metamorphism some of the carbon
dioxide, water, sulphur, arsenic, gold, silver and other metallic elements in the greenstones were mobilized and migrated by diffusion into the shear-zone systems. In the shear zones, water and carbon dioxide reacted with the amphibolite rock producing extensive widths of chlorite and
chloritecarbonate- sericite schist. Silica, iron, potassium and other elements and compounds were mobilized and migrated into dilatant zones in the shear zones where they were precipitated to form the mineralized gold-quartz lenses and veins. In the sediments, silica, boron, sulphur and various
metallic elements were mobilized during metamorphism and migrated into, and were precipitated in, dilatant zones in faults, fractures, and drag-folds.
‘Breek die tempel af’: Etiese dimensies in Johannes 2:13-22?
Authors: Van der Watt Jan G.
Published: August 2015

Destroy this temple’: Ethical dimensions in John 2:13–22? The question asked is to what extent could one speak of ethical dynamics in the Gospel of John, even in cases where there is no surface level textual evidence for the presence of ethical material? It is argued that through the process of rereading (‘relecture’), which is invited by the Johannine text as performative text, ethical dimensions are highlighted in texts where such emphases were not apparent at the first reading. As example the events at the temple, narrated in John 2:13–22, are analysed.
The effect of red wine extract, resveratrol, on the degree and rate of orthodontic tooth movement in guinea pigs
Authors: Urriquia Isidro Alex C. , Llavore Lotus D.
Published: August 2015

Objective

An animal trial, its protocol approved by the Institutional Animal Care and Use Committee of the U.P. National Institutes of Health (IACUC Protocol No. 2010-008), was employed to investigate the effects of resveratrol on the degree and rate of orthodontic tooth movement in guinea pigs.

Materials and Methods

Eighteen male adult guinea pigs were randomly allocated into 3 groups: low dose, high dose, and control groups. A 0.016″ titanium molybdenum alloy wire formed into a helical torsion spring with a coil, with the loops cemented onto the maxillary incisors of the animals, served as the orthodontic appliance. Daily oral administration of resveratrol was provided to the low dose (0.047 mg/kg) and high dose (0.47 mg/kg) groups, while water was provided to the control group. Measurements were taken everyday at the interproximal area at the level of the incisal edge using a measuring caliper.

Results

The results of the ANOVA showed no statistically significant differences in the mean measurements of tooth separation among the three groups from day 2 (P=0.966) to day 8 (P=0.056). However, starting from day 9 (P=0.049) until day 18 (P=0.000), there was a significant difference in the mean tooth separation among the test groups.

Conclusion

Using the LSD, it was noted that the low dose and the high dose groups have similar degrees of mean tooth separation, with the control group being significantly different from the two.
Evaluation of various anthropometric proportions in Indian beautiful faces: A photographic study
Authors: Kalra Saaransh , Bagga Dinesh Kumar , Agrawal Poonam
Published: August 2015

Introduction

The subject of beauty has been the topic of much debate throughout history, and methods for the evaluation of beauty have been the focus of many research projects. The evaluation of beauty is influenced by factors which include various linear measurements, angles, ratios, and proportions. We evaluated several ratios in Indian Population after locating various landmarks on beautiful Indian faces.

Aims and Objectives

The aim of the present study was to evaluate various facial proportions of Indian beauties using their frontal photographs in natural head position to establish anthropometric norms in beautiful Indian females. To evaluate whether these values satisfy golden and silver proportions. To compare these values with Caucasian anthropometric norms.

Materials and Methods

Frontal photographs of 30 female celebrities were downloaded from the internet. Photographs of only those Indian beauties that have been declared winners of either national or international beauty contests by a designated panel of judges were included in this study. Hardcopy of these photographs was taken in 5 inch by 3.5 inch format, all the measurements done and ratios calculated.

Results

Measurements were tabulated and values for various ratios were calculated to establish norms. Coefficient of variation was also evaluated.

Conclusion

All the ratios were found to be consistent than others which made it possible to assess beauty objectively rather than arbitrarily. Most of the values did not match the golden and silver proportion. In comparison with Caucasian population, we found that there is significant difference in most of the values.
An evaluation of panoramic radiograph to assess mandibular asymmetry as compared to posteroanterior cephalogram
Authors: Agrawal Astitva , Bagga Dinesh Kumar , Agrawal Poonam , Bhutani Ravindra Kumar
Published: August 2015

Aim and Objectives

To assess the reliability of orthopantomograms (OPGs) in detecting facial asymmetry.

Materials and Methods

The OPGs and posteroanterior cephalograms for 10 patients with facial asymmetry were obtained from the outpatient department of the dental college. These radiographs were traced and analyzed. Six measurements (four linear and two angular measurements) were made on both sides. Asymmetry was defined by subtracting the right and the left side measurements. The differences from OPG were compared to those obtained from posteroanterior cephalograms. The kappa statistics and intra-class correlation coefficient (ICC) were used to calculate the differences.

Results

The ICC was calculated between OPGs and posteroanterior cephalograms difference measurements. The class interval for all measurements was noted between 0.61 and 0.84. The ICC was 0.7861, which shows strong correlation between the values (P < 0.0005) by probability 10−5, within 95%, coefficient correlation lies between 0.61 and 0.84. Kappa test gives a value of 0.64, which shows strong agreement between the measurements.

Conclusion

Individually, the measurements from OPGs may not be reliable but the obtained difference between the values of the OPGs and the posteroanterior cephalograms are comparable in nature and show strong correlation and can be used to detect facial asymmetry.
Presurgical nasoalveolar molding therapy in cleft lip and palate individuals: Case series and review
Authors: Gandedkar Narayan H. , Kiat Chng Chai , Kanesan Palaniselvam , Lee Wen Cong , Chen Por Yong , Leng Yeow Vincent Kok
Published: August 2015

The nasoalveolar molding (NAM) therapy is advocated to reduce the severity of alveolar cleft and nasal deformity. NAM therapy has demonstrated to be an effective method for reducing cleft and improve nose anatomy. This paper presents a case report of three cleft lip and palate individuals treated with NAM therapy. Furthermore, the paper highlights the advantages of NAM therapy along with an enumeration of literature suggesting in favor of NAM therapy and otherwise. Regardless of controversies and divergent views involved with NAM therapy, the immediate success of NAM therapy facilitating primary lip repair surgery cannot be under-emphasized.
Management of skeletal Class III malocclusion with unilateral crossbite on a growing patient using facemask-bonded rapid palatal expander and fixed appliances
Authors: Effendy Tinnie , Soegiharto Benny M.
Published: August 2015

Facemask (FM) and bonded rapid palatal expander (RPE) are part of growth modification treatments for correcting skeletal Class III pattern with retrognathic maxilla. This orthopaedic treatment is usually preceded by fixed appliances to achieve aesthetic dental alignment and improve interdigitation. This case report reviews treatment of Class III malocclusion with unilateral crossbite in a 12-year-old boy using FM and bonded RPE, followed by fixed appliances. Choice of FM and bonded RPE was in line with indication which was mild Class III malocclusion with retrognathic maxilla. Execution of treatment was made considering treatment biomechanics and patient cooperation. This orthopaedic treatment was followed by orthodontic treatment specifically aimed to correct unilateral crossbite, canine relationship yet to reach Class I, lower midline shift, as well as unintended dental consequences of using bonded RPE, namely posterior open bite and deepening curve of spee. Posttreatment facial profile and smile are more esthetic. Occlusion is significantly improved both functionally and aesthetically.
Determination and Validation of a Solid-phase Extraction Gas Chromatography-mass Spectrometry for the Quantification of Methadone and Its Principal Metabolite in Human Plasma
Authors: Chiadmi Fouad , Schlatter Joël
Published: August 2015

This study aimed to develop a solid-phase extraction gas chromatography-selected ion monitoring-mass spectrometry method for the determination of methadone (MDN) and 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) in human plasma. The linear response was obtained over the concentration range from 10 to 2000 ng/mL for MDN and EDDP. The absolute recoveries of MDN and EDDP were 95.9%-98.9% and 94.8%-102.4%, with relative standard deviation (RSD) ranging from 1.8% to 2.7% and 1.8% to 3.9%, respectively. The intra- and interday precisions were found to be less than 5% for both analytes. The limits of detection of MDN and EDDP were 4 and 5 ng/mL, respectively. The presented method was convenient for therapeutic drug monitoring and pharmacokinetic studies in patients on heroin-assisted MDN therapy.
Stem Cells and Progenitor Cells for Tissue-Engineered Solutions to Congenital Heart Defects
Authors: Gao Yang , Jacot Jeffrey G.
Published: August 2015

Synthetic patches and fixed grafts currently used in the repair of congenital heart defects are nonliving, noncontractile, and not electrically responsive, leading to increased risk of complication, reoperation, and sudden cardiac death. Studies suggest that tissue-engineered patches made from living, functional cells could grow with the patient, facilitate healing, and help recover cardiac function. In this paper, we review the research into possible sources of cardiomyocytes and other cardiac cells, including embryonic stem cells, induced pluripotent stem cells, mesenchymal stem cells, adipose-derived stem cells, umbilical cord blood cells, amniotic fluid-derived stem cells, and cardiac progenitor cells. Each cell source has advantages, but also has technical hurdles to overcome, including heterogeneity, functional maturity, immunogenicity, and pathogenicity. Additionally, biomaterials used as patch materials will need to attract and support desired cells and induce minimal immune responses.
Cytomegalovirus-induced Hemorrhagic Colitis in a Patient with Chronic Myeloid Leukemia (Chronic Phase) on Dasatinib as an Upfront Therapy
Authors: Yassin Mohamed A. , Nashwan Abdulqadir J. , Soliman Ashraf T , Yousif Anil , Moustafa Afra , AlBattah Afaf , Mohamed Shehab F. , Mudawi Deena S. , Elkourashy Sarah , Asaari Deena-Raiza , Gutierrez Hope-Love G. , Almusharaf Mohamed , Hussein Radwa M. , Moustafa Abbas H. , El Derhoubi Hatim , Boukhris Sarra , Kohla Samah , AlDewik Nader
Published: August 2015

Dasatinib is a kinase inhibitor indicated for the treatment of newly diagnosed adults with Philadelphia chromosome–positive (Ph+) chronic myeloid leukemia (CML) in chronic phase and accelerated (myeloid or lymphoid blast) phase, and CML with resistance or intolerance to prior therapy including imatinib and in adults with Ph+ acute lymphoblastic leukemia 1 The most common adverse reactions (≥15%) in patients with newly diagnosed chronic-phase (CP) CML include myelosuppression, fluid retention, and diarrhea, whereas in patients with resistance or intolerance to prior imatinib therapy, side effects include myelosuppression, fluid retention, diarrhea, headache, dyspnea, skin rash, fatigue, nausea, and hemorrhage. We report a 39-year-old Ethiopian female patient who received dasatinib as upfront therapy for the treatment of CP-CML who experienced chronic diarrhea for two months, which progressed to hemorrhagic colitis due to cytomegalovirus (CMV) infection of the colon. To our knowledge, this is the first case of CMV colitis in a patient receiving dasatinib as upfront therapy.
The effects of temperature and scarification on seed germination of three Dalea species
Authors: Schellenberg M. P. , Biligetu B.
Published: August 2015

Schellenberg, M. P. and Biligetu, B. 2015. The effects of temperature and scarification on seed germination of three Dalea species. Can. J. Plant Sci. 95: 1117–1120. Ecological varieties of North American native plants are used for reclamation or rangeland seeding in Canada. The objectives of the study were to determine the optimum temperature for seed germination and to evaluate the effect of seed scarification on germination of ecological varieties of purple prairie clover [Dalea purpureum (Vent) Rydb.], white prairie clover [Dalea candida (Michx.) Willd.], and a wild collection of hairy prairie clover [Dalea villosa (Nutt.) Spreng var. villosa]. Germination was studied in growth chambers with constant temperatures of 5, 10, 20, and 30°C for 28 d using a randomized complete block design (RCBD). An additional germination experiment was conducted at 20°C after seed scarification. Based on days to initiate first germination and final germination, the optimum temperature for germination was 20°C for the three species. Final germination was the highest for purple prairie clover (51%), intermediate for white prairie clover (27%), and lowest for hairy prairie clover (5%). Seed scarification increased final germination by around 20% for all three species.
Modeling study of the 2010 regional haze event in the North China Plain
Authors: Gao M. , Carmichael G. R. , Wang Y. , Saide P. E. , Yu M. , Xin J. , Liu Z. , Wang Z.
Published: August 2015

Abstract. The online coupled Weather Research and Forecasting-Chemistry (WRF-Chem) model was applied to simulate a haze event that happened in January 2010 in the North China Plain (NCP), and was validated against various types of measurements. The evaluations indicate that WRF-Chem provides reliable simulations for the 2010 haze event in the NCP. This haze event is mainly caused by high emissions of air pollutants in the NCP and stable weather conditions in winter. Secondary inorganic aerosols also played an important role and cloud chemistry had important contributions. Air pollutants outside Beijing contributed about 47.8 % to the PM2.5 levels in Beijing during this haze event, and most of them are from south Hebei, Shandong and Henan provinces. In addition, aerosol feedback has important impacts on surface temperature, Relative Humidity (RH) and wind speeds, and these meteorological variables affect aerosol distribution and formation in turn. In Shijiazhuang, Planetary Boundary Layer (PBL) decreased about 300 m and PM2.5 increased more than 20 μg m-3 due to aerosol feedback. Feedbacks associated to Black Carbon (BC) account for about 50 % of the PM2.5 increases and 50 % of the PBL decreases in Shijiazhuang, indicating more attention should be paid to BC from both air pollution control and climate change perspectives.
Methane dynamics in warming tundra of Northeast European Russia
Authors: Marushchak M. E. , Friborg T. , Biasi C. , Herbst M. , Johansson T. , Kiepe I. , Liimatainen M. , Lind S. E. , Martikainen P. J. , Virtanen T. , Soegaard H. , Shurpali N. J.
Published: August 2015

Abstract. Methane (CH4) fluxes were investigated in a subarctic Russian tundra site in a multi-approach study combining plot scale data, ecosystem scale eddy covariance (EC) measurements and fine resolution land cover classification scheme for regional upscaling. The flux data as measured by the two independent techniques resulted in a seasonal (May–October 2008) cumulative CH4 emission of 2.4 (EC) and 3.7 g CH4 m−2 (manual chambers) for the source area representative of the footprint of the EC instruments. Upon upscaling for the entire study region of 98.6 km2, the chamber measured flux data yielded a regional flux estimate of 6.7 g CH4 m−2 yr−1. Our upscaling efforts accounted for the large spatial variability in the distribution of the various land cover types (LCTs) predominant at our study site. In particular, wetlands with emissions ranging from 34 to 53 g CH4 m−2 yr−1 were the most dominant CH4 emitting surfaces. Emissions from thermokarst lakes were an order of magnitude lower, while the rest of the landscape (mineral tundra) was a weak sink for atmospheric methane. Vascular plant cover was a key factor in explaining the spatial variability of CH4 emissions among wetland types, as indicated by the positive correlation of emissions with the leaf area index (LAI). As elucidated through a stable isotope analysis, the plant transport was the dominant CH4 release pathway that discriminates against heavier δ13C-CH4. The methane released from wetlands was lighter than that in the surface porewater and δ13C in the emitted CH4 correlated with the vascular plant cover (LAI) implying that the plant-mediated CH4 release dominates. A mean value of δ13C obtained here for the emitted CH4, −68.2 ± 2.0 ‰, is within the range of values from other wetlands, thus reinforcing the use of inverse modeling tools to better constrain the CH4 budget. Based on the IPCC A1B emission scenario, a temperature increase of 7 °C has been predicted for the tundra region of European Russia by the end of the 21st Century. A regional warming of this magnitude will have profound effects on the permafrost distribution leading to considerable changes in the regional landscape with a potential for an increase in the areal extent of methane emitting wet surfaces. We estimate that a projected increase in air temperature of 7 °C with a mere 10 % associated increase in the combined areal coverage of willow stands, fens and lakes in the region will lead to a 51 % higher amount of CH4 being emitted into the atmosphere by the end of this century.
Simulating the thermal regime and thaw processes of ice-rich permafrost ground with the land-surface model CryoGrid 3
Authors: Westermann S. , Langer M. , Boike J. , Heikenfeld M. , Peter M. , Etzelmüller B. , Krinner G.
Published: August 2015

Abstract. Thawing of permafrost in a warming climate is governed by a complex interplay of different processes, of which only conductive heat transfer is taken into account in most model studies. However, observations in many permafrost landscapes demonstrate that lateral and vertical movement of water can have a pronounced influence on the thaw trajectories, creating distinct landforms like thermokarst ponds and lakes even in areas where permafrost is otherwise thermally stable. Novel process parameterizations are required to include such phenomena in future projections of permafrost thaw and hereby triggered climatic feedbacks. In this study, we present a new land-surface scheme designed for permafrost applications, CryoGrid 3, which constitutes a flexible platform to explore new parameterizations for a range of permafrost processes. We document the model physics and employed parameterizations for the basis module CryoGrid 3, and compare model results with in-situ observations of surface energy balance, surface temperatures, and ground thermal regime from the Samoylov permafrost observatory in NE Siberia. The comparison suggests that CryoGrid 3 can not only model the evolution of the ground thermal regime in the last decade, but also consistently reproduce the chain of energy transfer processes from the atmosphere to the ground. In addition, we demonstrate a simple 1-D parameterization for thaw process in permafrost areas rich in ground ice, which can phenomenologically reproduce both formation of thermokarst ponds and subsidence of the ground following thawing of ice-rich subsurface layers. Long-term simulation from 1901–2100 driven by reanalysis data and climate model output demonstrate that the hydrological regime can both accelerate and delay permafrost thawing. If meltwater from thawed ice-rich layers can drain, the ground subsides while at the same time the formation of a talik is delayed. If the meltwater pools at the surface, a pond is formed which enhances heat transfer in the ground and leads to the formation of a talik. The model results suggest that the trajectories of future permafrost thaw are strongly influenced by the cryostratigraphy, as determined by the late quaternary history of a site.
Towards convection-resolving, global atmospheric simulations with the Model for Prediction Across Scales (MPAS): an extreme scaling experiment
Authors: Heinzeller D. , Duda M. G. , Kunstmann H.
Published: August 2015

Abstract. The Model for Prediction Across Scales (MPAS) is a novel set of earth-system simulation components and consists of an atmospheric model, an ocean model and a land-ice model. Its distinct features are the use of unstructured Voronoi meshes and C-grid discretisation to address shortcomings of global models on regular grids and of limited area models nested in a forcing data set, with respect to parallel scalability, numerical accuracy and physical consistency. This makes MPAS a promising tool for conducting climate-related impact studies of, for example, land use changes in a consistent approach. Here, we present an in-depth evaluation of MPAS with regards to technical aspects of performing model runs and scalability for three medium-size meshes on four different High Performance Computing sites with different architectures and compilers. We uncover model limitations and identify new aspects for the model optimisation that are introduced by the use of unstructured Voronoi meshes. We further demonstrate the model performance of MPAS in terms of its capability to reproduce the dynamics of the West African Monsoon and its associated precipitation. Comparing 11 month runs for two meshes with observations and a Weather Research & Forecasting tool (WRF) reference model, we show that MPAS can reproduce the atmospheric dynamics on global and local scales, but that further optimisation is required to address a precipitation excess for this region. Finally, we conduct extreme scaling tests on a global 3 km mesh with more than 65 million horizontal grid cells on up to half a million cores. We discuss necessary modifications of the model code to improve its parallel performance in general and specific to the HPC environment. We confirm good scaling (70 % parallel efficiency or better) of the MPAS model and provide numbers on the computational requirements for experiments with the 3 km mesh. In doing so, we show that global, convection-resolving atmospheric simulations with MPAS are within reach of current and next generations of high-end computing facilities.
The quantitative estimation of the vulnerability of brick and concrete building impacted by debris flow
Authors: Zhang J. , Guo Z. X. , Wang D. , Qian H.
Published: August 2015

Abstract. There is little historic data about the vulnerability of the damage elements in debris flow disaster in China. Therefore, it is difficult to estimate the vulnerability of debris flow quantitatively. This paper was devoted to the research of the vulnerability of brick and concrete building impacted by debris flow which widely existed in affected area. Under two assumptions, several prototype walls of brick and concrete were constructed to simulate the damaged structures in debris flow while the iron spheres were taken as the substitute of debris flow. The failure criterion of brick and concrete building was proposed with referring to the structure standards (brick and concrete) and the damage pattern in debris flow. The quantitatively estimation of vulnerability of brick and concrete building was finally established based on Fuzzy mathematics and the proposed failure criterion. The results show that the maximum impact bending moment is the best fit to be the disaster-causing factor in vulnerability curve and formula. The experiments in this paper is the preliminary research on the vulnerability of the element impacted by debris flow. The method and conclusion will be useful for the quantitative estimation of the vulnerability in debris flow and also can be referred in other types of the vulnerable elements research.
Summertime evolution of snow specific surface area close to the surface on the Antarctic Plateau
Authors: Libois Q. , Picard G. , Arnaud L. , Dumont M. , Lafaysse M. , Morin S. , Lefebvre E.
Published: August 2015

Abstract. On the Antarctic Plateau, snow specific surface area (SSA) close to the surface shows complex variations at daily to seasonal scales which affect the surface albedo and in turn the surface energy budget of the ice sheet. While snow metamorphism, precipitation and strong wind events are known to drive SSA variations, usually in opposite ways, their relative contributions remain unclear. Here, a comprehensive set of SSA observations at Dome C is analysed with respect to meteorological conditions to assess the respective roles of these factors. The results show an average two-to-three-fold SSA decrease from October to February in the topmost 10 cm, in response to the increase of air temperature and absorption of solar radiation in the snowpack during spring and summer. Surface SSA is also characterised by significant daily to weekly variations, due to the deposition of small crystals with SSA up to 100 m2 kg−1 onto the surface during snowfall and blowing snow events. To complement these field observations, the detailed snowpack model Crocus is used to simulate SSA, with the intent to further investigate the previously found correlation between inter-annual variability of summer SSA decrease and summer precipitation amount. To this end, Crocus parameterizations have been adapted to Dome C conditions, and the model was forced by ERA-Interim reanalysis. It successfully matches the observations at daily to seasonal time scales, except for few cases when snowfalls are not captured by the reanalysis. On the contrary, the inter-annual variability of summer SSA decrease is poorly simulated when compared to 14 years of microwave satellite data sensititve to the near surface SSA. A simulation with disabled summer precipitation confirms the weak influence in the model of the precipitation on metamorphism, with only 6 % enhancement. However we found that disabling strong wind events in the model is sufficient to reconciliate the simulations with the observations. This suggests that Crocus reproduces well the contributions of metamorphism and precipitation on surface SSA, but that snow compaction by the wind might be overestimated in the model.
Caracterización del Bosque Seco Tropical Remanente en el Valle de Agalta, Honduras
Authors: Mora José Manuel , Espinal Mario Roberto , López Lucía Isabel , Quezada Banny Omar
Published: August 2015

Identificamos 20 fragmentos de Bosque Seco Tropical en el valle de Agalta, Olancho, Honduras. Caracterizamos la estructura de la vegetación de los fragmentos y la dominancia e importancia relativa de las especies vegetales y otros parámetros dasométricos de su organización horizontal y vertical. Identificamos 265 especies de plantas, distribuidas en 78 familias y 223 géneros. El hábito dominante fue las hierbas (81 especies) seguido por los árboles (69 especies). Las familias más comunes fueron las leguminosas (Fabaceae) (36 especies), las orquídeas (17 especies) y las asteráceas (13 especies). Las asociaciones vegetales del valle de Agalta se mezclan con predominancia de los sistemas productivos antropogénicos. La presencia de ciertas especies vegetales sugiere que en el pasado cercano existieron asociaciones más húmedas en el valle. En la actualidad existe el bosque deciduo bajo y el bosque de pino–encino. El biscuite (Acacia deamii) tuvo la abundancia relativa más alta, seguido por el guamuche (Pithecelobium dulce). Esto puede ser el resultado de los rebrotes de las plantas existentes del bosque original. En el bosque de pino–encino dominaron las fagáceas Quercus sapoetifolia y Quercus segoviensis, con una contribución importante del nance (Byrsonima crassifolia, Malpighiaceae). Existe cierta conectividad entre algunos fragmentos de bosque seco tropical en Agalta a través de la vegetación remanente de los bosques rivereños. Lo anterior puede ser de vital importancia para la fauna del valle, en particular del colibrí esmeralda (Amazilia luciae), la única ave endémica de Honduras y clasificada como en peligro de extinción. El Bosque Seco Tropical es una de las zonas de vida menos representada en las áreas protegidas de Honduras a pesar de sus endemismos y la biodiversidad en general que contiene.Ceiba, 2012. Volumen 53(1):38-56
Ecología Política y Economía Ecológica construidas a partir de la Cultura Rural
Authors: Velásquez Hernández José Ramón
Published: August 2015

En este estudio se propone analizar los mecanismos culturales que las comunidades rurales de dos reservas naturales en Nicaragua: El Chocoyero- El Brujo y Miraflor-Moropotente, han desarrollo para el uso, manejo y conservación de los recursos naturales de sus entornos. Para la realización del mismo se llevó a cabo una revisión bibliográfica de textos especializados en la temática, y se relacionaron con evidencia empírica de las comunidades. Las mismas se caracterizan por poseer una importante reserva de recursos naturales que son utilizados en el desarrollo de las estrategias de vida. Las familias rurales poseen un amplio conocimiento sobre las formas de utilizar estos recursos naturales y cómo lograr la sustentabilidad de los mismos. Sin embargo el mercado capitalista y la articulación de los productores al mercado a través de rubros como la piña y la papa, ha cambiado paulatinamente la lógica de las instituciones económicas definidas históricamente por las comunidades que son las garantes de la conservación de los recursos naturales existentes. Tanto el mercado como el proceso de urbanización constituyen una amenaza latente para las comunidades.
Uso y Explotación de las tierras en Nicaragua
Authors: Castro Sobalvarro Ariana Karelya , Requene Acosta Grethel Carolina
Published: August 2015

El objetivo de este ensayo es dar a conocer el uso y explotación de la tierra en el sector agrícola nicaragüense. El método utilizado es de carácter descriptivo. Los datos provienen del IV Censo Agropecuario del INIDE, y para mayor comprensión se hará un acercamiento de variables utilizadas en los resultados de la encuesta. Los resultados obtenidos del análisis indican como ha sido la explotación y uso del suelo y se pueden mencionar: La crianza de aves, ganado; explotaciones en la actividad agrícola, manzanas sembradas con cultivos permanentes y semi-permanentes, siembra de granos básicos, etc. Se concluye que la encuesta brinda información del sector agropecuario e investiga variables nuevas de interés para el país como: Actividad principal de la Explotación Agropecuaria, tenencia de las parcelas, actividad acuícola en las Explotaciones Agropecuarias, característica de los miembros del hogar del productor(a) y seguridad alimentaria.