bluuebunny/crossref_metadata_2025 huggingface dataset:
Down-hole switching-mode power supply using a remote CA start up pulse
Authors: Mijarez Rito , Gomez Angel , Pascacio David , Martinez Ivan , Guevara Ricardo
Published: May 2016

The hydrocarbon industry leans heavily upon advanced technologies to extract oil and gas from greater depths and in harsher environments. The challenge to electronics manufacturers and designers is to make complex electronics work at the high temperatures, vibration, and extreme pressures encountered in these locations. Among the more critical electronic systems required for high temperature down-hole operations is high efficiency switching mode power supplies (SMPS). The use of high frequency switching permits not only decreasing the size of inductors and capacitors in the circuit design, but also obtaining typical power efficiencies up to 90%. Generally a SMPS is composed of a controller, a converter and silicon carbide (SiC) power switches. High temperature down-hole gauges operate with low voltages either 3.3V or 5.0V; however, wire-line surface power equipment utilizes higher voltages above 250 V CD. Hence, SMPS requires efficient power dissipation circuits to reduce the DC input voltage. This work describes a high temperature SMPS that has a DC input range from 150 V CD to 300 V CD, ± 6 V CD output voltages and 12 W total power. The SMPS design uses a CA start up pulse provided by a programmable surface power supply via a mono-conductor wire-line cable; subsequently, the SMPS sustains its operation by powering itself using one of the voltage outputs. The obtained laboratory tests results of the down-hole SMPS, using changes in temperature from 25 °C – 200 °C, provide a firm basis for testing and evaluating the DC-CD power supply in high temperature gauges in the field.
Silicon-Carbide Power MOSFET Performance in High Efficiency Boost Power Processing Unit for Extreme Environments
Authors: Ikpe Stanley A. , Lauenstein Jean-Marie , Carr Gregory A. , Hunter Don , Ludwig Lawrence L. , Wood William , Del Castillo Linda Y. , Mojarradi Mohammad M. , Fitzpatrick Fred , Chen Yuan
Published: May 2016

Silicon-Carbide (SiC) device technology has generated much interest in recent years. With superior thermal performance, power ratings and potential switching frequencies over its Silicon (Si) counterpart, SiC offers a greater possibility for high powered switching applications in extreme environment. In particular, SiC Metal-Oxide-Semiconductor Field-Effect Transistors' (MOSFETs) maturing process technology has produced a plethora of commercially available power dense, low on-state resistance devices capable of switching at high frequencies. A novel hard-switched power processing unit (PPU) is implemented utilizing SiC power devices. Accelerated life data is captured and assessed in conjunction with a damage accumulation model of gate oxide and drain-source junction lifetime to evaluate potential system performance at high temperature environments.
Toward Interpreting Failure in Sintered-Silver Interconnection Systems†
Authors: Modugno M. C. , Wereszczak A. A. , Waters S. B.
Published: May 2016

The mechanical strength and subsequent reliability of a sintered-silver interconnection “system” is a function of numerous independent parameters, and that “system” is still undergoing process development. Most of those parameters (e.g., choice of plating) are arguably and unfortunately often taken for granted and are independent of the silver's cohesive strength. To explore such effects, shear strength testing and failure analyses were completed on a simple, mock sintered-silver interconnection system consisting of bonding two DBC ceramic substrates. Silver and gold platings were part of the test matrix, as were drying strategies, and the consideration of stencil-printing vs. screen-printing. Shear strength of sintered-silver interconnect systems was found to be insensitive to the choice of plating, drying practice, and printing method provided careful and consistent processing of the sintered-silver are practiced. Lastly, with the examined interconnection systems, it was observed that a maximum shear failure stress of ~ 60 MPa is achievable.
Nanocomposite Film Dielectrics for High Temperature Power Conditioning Capacitors
Authors: Slenes Kirk , Perry Dale , Bragg Lew
Published: May 2016

Emerging power electronics in a broad range of military, aerospace, hybrid vehicle, renewable energy and drilling applications rely on advances in dielectric materials for capacitors. Compact capacitors possessing low dielectric loss and high operating temperature capability are needed for power conditioning in advanced converter and inverter designs for these applications. Wound film capacitors represent the preferred capacitor technology but are limited by low operating temperature capabilities, < 150°C, and low volumetric efficiency, capacitance per unit volume less than 1.0 μF/cc.

TPL is developing processes and manufacturing techniques for fabrication of advanced capacitor films comprised of high temperature polymers modified with ceramic nanoparticles. The selected polymers enable high temperature operation and the ceramic nanoparticles enhance volumetric efficiency by increasing the dielectric constant. The fabricated films are adaptable to conventional wound film capacitor construction methodologies.

This paper provides an overview of TPL's experience to-date with a film dielectric material system comprised of fluorenone polyester polymer and titanate nanoparticle filler. The fluorenone polyester polymer was selected to provide a stable operating temperature of at least 200°C, while the addition of the titanate powder increases the dielectric constant and, in turn, the volumetric efficiency of wound film capacitors constructed with this film system. Status and ongoing capacitor development issues are provided relative to the intended high temperature power conditioning applications.
Design of High Temperature Combline Band-pass Filters for Downhole Communications
Authors: Ehteshamuddin Mohammed , Salem Jebreel M. , Ha Dong Sam
Published: May 2016

The decline of easily accessible reserves pushes the oil and gas industry to drill deeper to explore previously untapped wells. Temperatures in these wells can exceed 210 °C. Cooling and conventional heat extraction techniques are impractical in such a harsh environment. Reliable electronic designs that can sustain high temperature become necessary. This paper presents RF and IF microstrip combline band-pass filters for downhole communications, which can reliably operate up to 250 °C. Both filters are prototyped on a Rogers RO4003C substrate. Measured results at 250 °C show that the RF and IF filters have insertion losses of 4.53 dB and 3.45 dB, respectively. Both filters have stable performance at high temperatures. The maximum insertion loss variation with temperature for the RF filter is 1.88 dB, and bandwidth variation is 1.3 MHz. The maximum insertion loss variation with temperature for the IF filter is 1.48 dB, and bandwidth variation is 0.4 MHz. Return loss for the RF filter is more than 12 dB, and for the IF filter more than 10 dB in the passband. This paper also describes a simple method to find spacing between coupled symmetrical microstrip lines of a combline filter.
High Precision Analog Multiplexers Enable Multi-Channel Data Acquisition in High Temperature Environments
Authors: Watson Jeff , Kavanagh Stephen , Nugent Stephen
Published: May 2016

A growing number of industries are calling for low power electronics that operate reliably at temperatures of 175C and higher. Many of these applications require a precision data acquisition signal chain in order to digitize analog data so that it can be collected and processed. We previously presented a characterized signal chain for a single channel of analog to digital conversion designed around a 600ks ps SAR ADC. However, many systems have a multitude of sensor signals that must be acquired at varying sample rates. In this work we discuss two new analog multiplexers rated for 175°C/210°C that allow multiple analog signals to be connected to the ADC input, enabling the design of a precision multi-channel data acquisition system. One multiplexer is designed on a robust dielectrically isolated process for high performance and low leakage over temperature, and one multiplexer is optimized for low power, low voltage applications. We will examine the architecture of these two integrated circuits, review the characterization over temperature and discuss example application signal chains.
Improving Efficiency in Downhole Power Converters using GaN Technology
Authors: Hanington Gary
Published: May 2016

In downhole applications, the ability to convert wildly varying wireline voltages standard +/− 15 VDC stretches the limit on switching converters whose components have to be rugged, compact, and offer low thermal paths to surrounding metal housings. Many times the incoming voltages exceed 200V with spikes above 500 quite common. Functioning in extreme environments up to 200 degrees Celsius requires the designer to squeeze out the highest power efficiency possible and every percent increase is an important milestone. Over the past three decades silicon devices were the only technology available that could be made to work at such temperatures, almost always bypassing the manufacturer's maximum specifications. In the past several years wide bandgap semiconductors have become available that offer new possibilities for operation at elevated temperatures. This paper discusses the efficiency improvements when silicon power devices are replaced with gallium nitride based components. By utilizing GaN High Electron Mobility Transistors (HEMTs) in an existing H bridge phase shifted converter, efficiency improvements of up to 9% have been achieved at 175 °C operation. Advantages of HEMT devices compared to silicon are discussed and associated loss mechanisms of both are compared.
Supply chain integration in the South African conveyancing environment
Authors: Amadi-Echendu Anthea P. , Krüger Louis P.
Published: May 2016

Background: Although conveyancing is a legal term, business management and specifically operations management principles also apply to the processes involved in conveyancing. From a business perspective, each organisation is usually concerned with its own profit margins and processes. In our global market, however, organisations now realise that they can no longer compete successfully on the basis of their internal operational efficiencies alone. They are therefore constantly aware of the need to improve not only their internal processes but also their alignment with other supply chain linkages in an effort to optimise the performance of the whole supply chain. Such alignment, in the conveyancing environment, includes government departments that are generally less willing to adopt business principles, which in turn makes optimisation of the whole supply chain more difficult.Objectives: The article describes a supply chain perspective of the conveyancing processes in South Africa and reports some of the factors that influence and delay conveyancing transactions. It explores possibilities of collaborative relationships between different role players in the conveyancing supply chain. It aims to show that a supply chain approach, as opposed to a singular organisational approach, can help to reduce process bottlenecks and delays in order to improve overall process efficiency.Method: The research, on which the findings are based, was exploratory in nature and followed a mixed-methods (quantitative or qualitative) approach and included both structured questionnaires and personal interviews.Results: The results of the study revealed that many different types of delays occur at various entities across the whole supply chain involved in property transfers. These delays are presented in a table and diagram.Conclusion: It is recommended that greater adoption of electronic technology across the whole supply chain would improve overall efficiency, eliminate bottlenecks and contribute towards efforts to optimise the conveyancing supply chain in South Africa. In addition, it is also recommended that the South African deeds registry implement an electronic system which would allow for the electronic lodging of property transfers.Keywords: e-conveyancing; electronic processes; digitisation of data; supply chain management; integration
Sero-epidemiological survey and risk factors associated with bovine brucellosis among slaughtered cattle in Nigeria
Authors: Akinseye Victor O. , Adesokan Hezekiah K. , Ogugua Akwoba J. , Adedoyin Folashade J. , Otu Patricia I. , Kwaghe Ayi V. , Kolawole Noah O. , Okoro Oyinye J. , Agada Charity A. , Tade Adeniyi O. , Faleke Olufemi O. , Okeke Anyanwu L. , Akanbi Ibikunle M. , Ibitoye Mofoluwake M. , Dipeolu Morenike O. , Dale Emma J. , Lorraine Perrett , Taylor Andrew V. , Awosanya Emmanuel A. , Cadmus Eniola O. , Stack Judy A , Cadmus Simeon I.
Published: May 2016

Bovine brucellosis is endemic in Nigeria; however, limited data exist on nationwide studies and risk factors associated with the disease. Using a cross-sectional sero-epidemiological survey, we determined the prevalence of and risk factors for brucellosis in slaughtered cattle in three geographical regions of Nigeria. Serum samples from randomly selected unvaccinated cattle slaughtered over a period of 3 years (between December 2010 and September 2013) from northern, southern and south-western Nigeria were tested for antibodies to Brucella abortus using the Rose Bengal test. Data associated with risk factors of brucellosis were analysed by Stata Version 12. In all, 8105 cattle were screened. An overall seroprevalence of 3.9% (315/8105) was recorded by the Rose Bengal test, with 3.8%, 3.4% and 4.0% from the northern, southern and south-western regions, respectively. Bivariate analysis showed that cattle screened in northern Nigeria were less likely to be seropositive for antibodies to Brucella spp. than those from south-western Nigeria (odds ratio = 0.94; 95% confidence interval: 0.73–1.22). However, logistic regression analysis revealed that breed ( p = 0.04) and sex ( p £ 0.0001) of cattle were statistically significant for seropositivity to Brucella spp. The study found that brucellosis was endemic at a low prevalence among slaughtered cattle in Nigeria, with sex and breed of cattle being significant risk factors. Considering the public health implications of brucellosis, we advocate coordinated surveillance for the disease among diverse cattle populations in Nigeria, as is carried out in most developed countries.Keywords: Bovine brucellosis, RBT, Epidemiology, Public Health, Nigeria
Challenges faced by professional nurses when implementing the Expanded Programme on Immunisation at rural clinics in Capricorn District, Limpopo
Authors: Mothiba Tebogo M. , Tladi Flora M.
Published: May 2016

Background: Immunisation is the cornerstone of primary healthcare. Apart from the provision of safe water, immunisation remains the most cost-effective public health intervention currently available. Immunisation prevents infectious conditions that are debilitating, fatal and have the potential to cause huge public health burdens, both financially and socially, in South Africa.Aim: To determine the challenges faced by professional nurses when implementing the Expanded Programme on Immunisation (EPI) at rural clinics in Capricorn District, Limpopo Province, South Africa.Setting: The study was conducted in selected primary healthcare clinics of Capricorn District, Limpopo Province.Methods: A qualitative explorative descriptive contextual research design was used to gather data related to the challenges faced by professional nurses when implementing EPI at rural clinics in Capricorn District.Results: The findings revealed that professional nurses had knowledge of the programme, but that they experienced several challenges during implementation of EPI that included staff shortages and problems related to maintenance of the vaccines’ potency.Conclusions: The Department of Health as well as the nursing administration should monitor policies and guidelines, and especially maintenance of a cold chain for vaccines, to ensure that they are practised throughout Limpopo Province. The problem of staff shortages also needs to be addressed so that the EPI can achieve its targeted objectives.Keywords: Professional nurse, knowledge, EPI-SA, immunisation
Targeted temperature management in neurocritical care: Boon or bust
Authors: Bindra Ashish , Gupta Deepak
Published: May 2016

Temperature management in neurocritical care is important and has gained due importance in recent years. Targeted temperature management (TTM) includes deliberate reduction of core body temperature to a range of 32–34°C in comatose survivors of cardiac arrest after return of spontaneous circulation and also therapeutic hypothermia (33–35°C) in normothermic patients or controlled normothermia (cooling patients to 37°C) in hyperthermic patients. This review focuses on the practical aspects of cooling and temperature management in neurocritical care. An electronic search of Google Scholar, MEDLINE (OVID), EMBASE and the Cochrane library was performed. The physiological changes, potential side effects along with significant research and clinical applications in the field of temperature management are main highlights. Currently, the research evidence is available for TTM in adults following cardiac arrest, neonatal hypoxic ischaemic encephalopathy and raised intracranial pressure. Controlled normothermia in neurocritical care population is rapidly gaining popularity. However, data on disease specific therapeutic markers, therapeutic depth and duration and prognostication of this modality are limited. Overall in experienced hands, the technique is safe to execute without the major morbidity and a potential to improve the outcome. Though over the years, clinical applications are unable to consistently demonstrate its benefits, but TTM in neurological insult has become an established and promising concept.
Artin Approximation Compatible with a Change of Variables
Authors: Fichou Goulwen , Quarez Ronan , Shiota Masahiro
Published: May 2016

We propose a version of the classical Artin approximation that allows us to perturb the variables of the approximated solution. Namely, it is possible to approximate a formal solution of a Nash equation by a Nash solution in a compatible way with a given Nash change of variables. This result is closely related to the so-called nested Artin approximation and becomes false in the analytic setting. We provide local and global versions of this approximation in real and complex geometry together with an application to the Right-Left equivalence of Nash maps.
Les joueurs sans problème de jeu de 55 ans et plus : événements, conséquences et caractéristiques structurelles et environnementales influençant les habitudes de jeu
Authors: Giroux Isabelle , Ferland Francine , Savard Cathy , Jacques Christian , Brochu Priscilla , Nadeau Dominic , Landreville Philippe , Sévigny Serge
Published: May 2016

Gambling habits of people aged 55 years and over without gambling problems are rarely being investigated. In order to document life events and to identify the impacts of gambling on quality of life, 19 participants aged 55 to 74 years without gambling problems, male and female, were assembled in three focus groups. Qualitative content analysis of the groups reveals changes in gambling habits associated with transition to retirement and occurrence of health problems. The content analysis further reveals a variety of positive and negative consequences of gambling habits on finances, hobbies, social relationships, and psychological health. Although the focus groups did not target the structural or environmental characteristics of gambling that influence participants' gambling habits, those themes were brought up spontaneously. Results highlight the necessity to study life events from a larger perspective including, for example, protective and risk factors, in order to better understand the life contexts and the individual characteristics that may lead to an alteration or not of gambling habits.
Funding of Gambling Research: Ethical Issues, Potential Benefit and Guidelines
Authors: Kim Hyoun S. , Dobson Keith S. , Hodgins David C.
Published: May 2016

There has been an unprecedented growth of legalized gambling opportunities in Canada over the past two decades, partly to generate revenues without raising taxes. Unfortunately, for 2-3% of the Canadian population, gambling can become disordered (i.e. develop into a gambling addiction). To help attenuate the harms and prevalence of disordered gambling, all provincial governments earmark a portion of gambling revenues for the prevention, treatment and research into disordered gambling. However, the field of gambling studies has recently come under criticism in the way research is conducted. At the forefront of the criticism is the issue of accepting funding from the gambling industry. We provide an overview of the ethical considerations, potential ethical issues, and the possible benefits of accepting such funding. The aim of the present paper is not to argue for or against accepting industry funding, but rather to delineate the potential ethical issues and benefits related to that acceptance. More importantly, we provide a summary of best practice ethical guidelines, and recommendations to guide in the ethical decision making process in accepting or declining funding from gambling industry. To this end, we use the Canadian Code of Ethics for Psychologists as a framework in which to situate our guidelines and recommendations. Given that Canadian researchers have a long history and continue to contribute valuable knowledge in the field of gambling studies, it is of important for gambling researchers to be aware of the ethical considerations and issues related to funding from gambling industry.
Episodic Chasing and Price of Scratch-off Lottery Tickets
Authors: Whiting Seth W. , Catrone Rocco Giovanni , Babbra Amrinder
Published: May 2016

The present study examined the relationship between instant (scratch-off) lottery ticket price and "chasing losses" within a single gambling episode. Across several months, each time an instant lottery ticket was purchased (N = 1081), convenience store clerks recorded the gamblers' genders, the price of the tickets purchased, and whether the customer purchased another ticket before leaving the premises. Logistic regression analysis showed a significant association between ticket price and repurchasing (odds ratio = .842, p < .0001), suggesting within-session chasing is common with lower priced instant lottery tickets, and lower costs are not necessarily indicative of less risk.
Marine boundary layer structure as observed by A-train satellites
Authors: Luo Tao , Wang Zhien , Zhang Damao , Chen Bing
Published: May 2016

Abstract. The marine boundary layer (MBL) structure is important to the marine low cloud processes, and the exchange of heat, momentum, and moisture between oceans and the low atmosphere. This study examines the MBL structure over the eastern Pacific region and further explores the controlling factors of MBL structure over the global oceans with a new 4-year satellite-based data set. The MBL top (boundary layer height, BLH) and the mixing layer height (MLH) were identified using the MBL aerosol lidar backscattering from the CALIPSO (Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations). Results showed that the MBL is generally decoupled with MLH ∕ BLH ratio ranging from  ∼  0.5 to  ∼  0.8 over the eastern Pacific Ocean region. The MBL decoupling magnitude is mainly controlled by estimated inversion strength (EIS), which in turn controls the cloud top entrainment process. The systematic differences between drizzling and non-drizzling stratocumulus tops also show dependence on EIS. This may be related to the meso-scale circulations or gravity wave in the MBL. Further analysis indicates that the MBL shows a similar decoupled structure for clear-sky and cumulus-cloud-topped conditions, but is better mixed under stratiform cloud breakup and overcast conditions.
Detection of dimethylamine in the low pptv range using nitrate chemical ionization atmospheric pressure interface time-of-flight (CI-APi-TOF) mass spectrometry
Authors: Simon Mario , Heinritzi Martin , Herzog Stephan , Leiminger Markus , Bianchi Federico , Praplan Arnaud , Dommen Josef , Curtius Joachim , Kürten Andreas
Published: May 2016

Abstract. Amines are potentially important for atmospheric new particle formation, but their concentrations are usually low with typical mixing ratios in the pptv range or even smaller. Therefore, the demand for highly sensitive gas-phase amine measurements has emerged in the last several years. Nitrate chemical ionization mass spectrometry (CIMS) is routinely used for the measurement of gas-phase sulfuric acid in the sub-pptv range. Furthermore, extremely low volatile organic compounds (ELVOCs) can be detected with a nitrate CIMS. In this study we demonstrate that a nitrate CIMS can also be used for the sensitive measurement of dimethylamine (DMA, (CH3)2NH) using the NO3−•(HNO3)1 − 2• (DMA) cluster ion signal. Calibration measurements were made at the CLOUD chamber during two different measurement campaigns. Good linearity between 0 and  ∼  120 pptv of DMA as well as a sub-pptv detection limit of 0.7 pptv for a 10 min integration time are demonstrated at 278 K and 38 % RH.
Technical note: Sampling and processing of mesocosm sediment trap material for quantitative biogeochemical analysis
Authors: Boxhammer Tim , Bach Lennart T. , Czerny Jan , Riebesell Ulf
Published: May 2016

Abstract. Sediment traps are the most common tool to investigate vertical particle flux in the marine realm. However, the spatial and temporal decoupling between particle formation in the surface ocean and particle collection in sediment traps at depth often handicaps reconciliation of production and sedimentation even within the euphotic zone. Pelagic mesocosms are restricted to the surface ocean, but have the advantage of being closed systems and are therefore ideally suited to studying how processes in natural plankton communities influence particle formation and settling in the ocean's surface. We therefore developed a protocol for efficient sample recovery and processing of quantitatively collected pelagic mesocosm sediment trap samples for biogeochemical analysis. Sedimented material was recovered by pumping it under gentle vacuum through a silicon tube to the sea surface. The particulate matter of these samples was subsequently separated from bulk seawater by passive settling, centrifugation or flocculation with ferric chloride, and we discuss the advantages and efficiencies of each approach. After concentration, samples were freeze-dried and ground with an easy to adapt procedure using standard lab equipment. Grain size of the finely ground samples ranged from fine to coarse silt (2–63 µm), which guarantees homogeneity for representative subsampling, a widespread problem in sediment trap research. Subsamples of the ground material were perfectly suitable for a variety of biogeochemical measurements, and even at very low particle fluxes we were able to get a detailed insight into various parameters characterizing the sinking particles. The methods and recommendations described here are a key improvement for sediment trap applications in mesocosms, as they facilitate the processing of large amounts of samples and allow for high-quality biogeochemical flux data.
A high-altitude peatland record of environmental changes in the NW Argentine Andes (24 ° S) over the last 2100 years
Authors: Schittek Karsten , Kock Sebastian T. , Lücke Andreas , Hense Jonathan , Ohlendorf Christian , Kulemeyer Julio J. , Lupo Liliana C. , Schäbitz Frank
Published: May 2016

Abstract. High-altitude cushion peatlands are versatile archives for high-resolution palaeoenvironmental studies, due to their high accumulation rates, range of proxies, and sensitivity to climatic and/or human-induced changes. Especially within the Central Andes, the knowledge about climate conditions during the Holocene is limited. In this study, we present the environmental and climatic history for the last 2100 years of Cerro Tuzgle peatland (CTP), located in the dry Puna of NW Argentina, based on a multi-proxy approach. X-ray fluorescence (XRF), stable isotope and element content analyses (δ13C, δ15N, TN and TOC) were conducted to analyse the inorganic geochemistry throughout the sequence, revealing changes in the peatlands' past redox conditions. Pollen assemblages give an insight into substantial environmental changes on a regional scale. The palaeoclimate varied significantly during the last 2100 years. The results reflect prominent late Holocene climate anomalies and provide evidence that in situ moisture changes were coupled to the migration of the Intertropical Convergence Zone (ITCZ). A period of sustained dry conditions prevailed from around 150 BC to around AD 150. A more humid phase dominated between AD 200 and AD 550. Afterwards, the climate was characterised by changes between drier and wetter conditions, with droughts at around AD 650–800 and AD  1000–1100. Volcanic forcing at the beginning of the 19th century (1815 Tambora eruption) seems to have had an impact on climatic settings in the Central Andes. In the past, the peatland recovered from climatic perturbations. Today, CTP is heavily degraded by human interventions, and the peat deposit is becoming increasingly susceptible to erosion and incision.
EnKF and 4D-Var Data Assimilation with a Chemistry Transport Model
Authors: Skachko Sergey , Menard Richard , Errera Quentin , Christophe Yves , Chabrillat Simon
Published: May 2016

Abstract. We compare two optimized chemical data assimilation systems, one based on the ensemble Kalman filter (EnKF) and the other based on four-dimensional variational (4D-Var), using a comprehensive stratospheric chemistry transport model (CTM). The work is an extension of the Belgian Assimilation System for Chemical ObsErvations (BASCOE), initially designed to work with a 4D-Var data assimilation. A strict comparison of both methods in the case of chemical tracer transport was done in a previous study and indicated that both methods provide essentially similar results. In the present work, we assimilate observations of ozone, HCl, HNO3, H2O and N2O from EOS Aura-MLS data into the BASCOE CTM with a full description of stratospheric chemistry. Two new issues related to the use of full chemistry model with EnKF are taken into account. One issue concerns to a large number of error variance parameters that need to be optimized. We estimate an observation error parameter as function of pressure level for each observed species using the Desroziers' method. For comparison reasons, we apply the same estimate procedure in the 4D-Var data assimilation, where we keep both estimates: the background and observation error variances. However in EnKF, the background error covariance is modelled using the full chemistry model and a model error term. We found that it is adequate to have a single model error based on the chemical tracer formulation that is applied for all species. This is an indication that the main source of model error in chemical transport model is due to the transport. The second issue in EnKF with comprehensive atmospheric chemistry models is the sampling errors between species. When species are weakly chemically related, cross-species sampling noise errors occur at the same location. These errors need to be filtered out, in addition to a localization based on distance. The performance of two data assimilation methods was assessed through an eight-month long assimilation of limb sounding observations from EOS Aura-MLS. The paper discusses the differences in results and their relation to stratospheric chemical processes. Generally speaking, EnKF and 4D-Var provide results of comparable quality but differ substantially in presence of model error or observation biases. If the erroneous chemical modelling is associated with not too small chemical life-times, then EnKF performs better, while 4D-Var develops spurious increments in the chemically related species. If, on the other hand, the observation biases are significant, then 4D-Var is more robust and is able to reject erroneous observations, while EnKF does not.
A New Remote Hazard and Risk Assessment Framework for Glacial Lakes in the Nepal Himalaya
Authors: Rounce David R. , McKinney Daene C. , Lala Jonathan M. , Byers Alton C. , Watson C. Scott
Published: May 2016

Abstract. Glacial lake outburst floods (GLOFs) pose a significant threat to downstream communities and infrastructure due to their potential to rapidly unleash stored lake water. The most common triggers of these GLOFs are mass movement entering the lake and/or the self-destruction of the terminal moraine due to hydrostatic pressures or a buried ice core. This study initially uses previous qualitative and quantitative assessments to understand the hazards associated with eight glacial lakes in the Nepal Himalaya that are widely considered to be highly dangerous. The previous assessments yield conflicting classifications with respect to each glacial lake, which spurred the development of a new holistic, reproducible, and objective approach based solely on remotely sensed data. This remote hazard assessment analyzes mass movement entering the lake, the stability of the moraine, and lake growth in conjunction with a geometric GLOF to determine the downstream impacts such that the present and future risk associated with each glacial lake may be quantified. The new approach is developed within a hazard, risk, and management action framework with the aim that this remote assessment may guide future field campaigns, modeling efforts, and ultimately risk-mitigation strategies. The remote assessment was found to provide valuable information regarding the hazards faced by each glacial lake and results were discussed within the context of the current state of knowledge to help guide future efforts.
Surface-layer turbulence, energy-balance and links to atmospheric circulations over a mountain glacier in the French Alps
Authors: Litt Maxime , Sicart Jean-Emmanuel , Six Delphine , Wagnon Patrick , Helgason Warren D.
Published: May 2016

Abstract. Over mountain glaciers, large errors may affect turbulent surface heat fluxes estimated with the bulk-aerodynamic (BA) method. That might lead to uncertainties in estimating melt from surface energy balance (SEB). During the summers of 2006 and 2009, in the atmospheric surface layer of Saint-Sorlin Glacier (French Alps, 45° N, 6.1° E, ~3 km2), mean air-temperature and wind-speed vertical profiles and high frequency Eddy-Covariance (EC) data were collected to characterize the turbulence and the turbulent fluxes. We studied the influence of the BA method errors on the melt estimations, calculating the SEB alternatively with turbulent fluxes obtained from the BA and the EC methods. We classified our results in terms of large-scale forcing. In weak synoptic forcing, local thermal effects dominated the wind circulation. On the glacier, weak katabatic flows with a wind-speed maximum at low height (2–3 m) were detected 71 % of the time and were generally associated with weak turbulent kinetic energy (TKE) and turbulent fluxes. When the large-scale forcing was strong, the wind in the valley aligned with the glacier flow, intense downslope flows were observed, no wind-speed maximum was visible below 5 m, TKE and turbulent fluxes were often intense. For both regimes, the surface layer turbulence production was probably not at equilibrium with dissipation because of the interaction of large-scale orographic disturbances with the flow when the forcing was strong, or low-frequency oscillations of the katabatic flow when the forcing was weak. When TKE was low, all turbulent fluxes calculation methods provided similar fluxes. When TKE was large, the EC method provided larger fluxes than the BA method. This underestimation was compensated by increasing the BA flux estimates using melt-calibrated effective roughness lengths. Though strong forcing was more frequently associated with large TKE events than weak forcing conditions, differences between the different SEB estimates remained in both cases within the error range of observed melt.
Resource Allocation on a Hybrid Cloud for Smart Grids
Authors: Briones Alan , Martín de Pozuelo Ramon , Navarro Joan , Zaballos Agustín
Published: May 2016

The use of hybrid clouds enables companies to cover their demands of IT resources saving costs and gaining flexibility in the deployment of infrastructures by paying under demand these resources. However, considering a scenario with various services to be allocated in more than one cloud, it is necessary to find the distribution of services that minimizes the overall operating costs. This paper researches on the resource allocation methodology to be applied in a multi-cloud scenario based on the findings derived from the framework used for the FINESCE project. The purpose of this work is to define a methodology to assist on the hybrid cloud selection and configuration in the Smart Grid for both generic and highly-constrained scenarios in terms of latency and availability. Specifically, the presented method is aimed to determine which is the best cloud to allocate a resource by (1) optimizing the system with the information of the network and (2) minimizing the occurrence of collapsed or underused virtual machines. Also, to assess the performance of this method and any alternative proposals, a general set of metrics has been defined. These metrics have been refined taking into account the expertise of FINESCE partners in order to shape Smart Grid clouds and reduce the complexity of computation. Finally, using the data extracted from the FINESCE testbed, a decision tree is used to come up with the best resource allocation scheme.
Using Factor Analysis Techniques to Find Out Objective Video Quality Metrics for Live Video Streaming over Cloud Mobile Media Services
Authors: Garcia-Pineda Miguel , Felici-Castell Santiago , Segura-Garcia Jaume
Published: May 2016

The increased adoption of smartphones, the access to mobile broadband networks and the availability of public Clouds allow new multimedia services, called Cloud Mobile Media Services. Under this new architecture the proliferation of live video streaming applications and the Quality of Experience (QoE) given by the final user are an issue, due to the higher and variable delay, as result of the virtualization methods used in the Clouds. Thus in this paradigm new challenges appear related to keep and estimate a good QoE in terms of a standarized subjective video quality called Mean Opinion Score (MOS). In this paper we analyze different approaches based on Factor Analysis techniques to estimate the subjective MOS both using Full Reference and Non Reference approaches. We compare the performance of the estimated MOS against publicly available video quality algorithms.
Investigación en el aula: Diarios de aprendizaje en el contexto universitario de postgrados
Authors: Soriano Rodríguez Ana María
Published: May 2016

Este artículo sistematiza y analiza la práctica del Diario de Aprendizaje en el desarrollo de la asignatura Investigación Educativa, del Curso de Formación Pedagógica en la Universidad Don Bosco, El Salvador, durante ciclo I-2015. El análisis de resultados evidencia los intereses, aprendizajes y limitantes de los 23 estudiantes dentro y fuera del salón de clases. Además, reflejan la contribución a la comunicación docente-estudiante y la autoevaluación tanto del maestro como de los alumnos. El objetivo principal de esta experiencia educativa fue evidenciar la factibilidad de realizar investigación en el aula y su contribución a la mejora continua de los procesos educativos.Diá-logos 16, 21-37
Post-radiation epithelioid angiosarcoma of the urinary bladder and prostate
Authors: Wang Gang , Black Peter C. , Skinnider Brian F. , Hayes Malcolm M. , Jones Edward C.
Published: May 2016

Angiosarcoma of the lower urinary tract is exceedingly rare. A minority of cases are associated with local radiotherapy. Epithelioid angiosarcoma is a variant of angiosarcoma composed of large rounded epithelioid endothelial cells that are positive for cytokeratin on immunostaining. There are only two cases of post-radiation epithelioid angiosarcoma reported in the urinary bladder, and none in the prostate gland. We report a case of epithelioid angiosarcoma involving the urinary bladder and prostate in a patient with a history of radiotherapy for prostatic adenocarcinoma. A brief review of literature regarding post-radiation epithelioid angiosarcomas in the lower urinary tract is discussed.
Urinary mycobacterium avium presenting as sterile pyuria
Authors: Yang Kai , Samplaski Mary , Mazzulli Tony , Lo Kirk , Grober Ethan , Jarvi Keith Allen
Published: May 2016

A 65-year-old healthy woman presented with persistent, asymptomatic sterile pyuria detected by her family physician. While she did not have symptoms, the patient recounts that she has had cloudy urine for years. Cultures of the urine for bacteria showed no growth and no fungi were identified. First-morning urine samples were sent for both tuberculosis and nontuberculosis mycobacterium species testing. The culture grew genotypically identified Mycobaterium avium complex (MAC). Mantoux skin testing was positive. No urological abnormalities were detected by ultrasound and computed tomography (CT) imaging of the urinary tract.
Effect of adipose tissue-derived stem cell injection in a rat model of urethral fibrosis
Authors: Sangkum Premsant , Yafi Faysal A. , Kim Hogyoung , Bouljihad Mostafa , Ranjan Manish , Datta Amrita , Mandava Sree Harsha , Sikka Suresh C. , Abdel-Mageed Asim B. , Hellstrom Wayne J.G.
Published: May 2016

Introduction: We sought to evaluate the therapeutic effect of adipose tissue-derived stem cells (ADSCs) in a rat model of urethral fibrosis.Methods: Eighteen (18) male Sprague-Dawley rats (300‒350 g) were divided into three groups: (1) sham (saline injection); (2) urethral fibrosis group (10 μg transforming growth factor beta 1 (TGF-β1) injection); and (3) ADSCs group (10 μg TGF-β1 injection plus 2 x 105 ADSCs). Rat ADSCs were harvested from rat inguinal fat pads. All study animals were euthanized at two weeks afterurethral injection. Following euthanasia, rat urethral tissue was were quantitated by Western blot analysis. Results: TGF-β1 injection induced significant urethral fibrosis and increased collagen type I and III expression (p<0.05). Significant decrease in submucosal fibrosis and collagen type I and III expression were noted in the ADSCs group compared with the urethral fibrosis group (p<0.05). TGF-β1 induced fibrotic changes were ameliorated by injection of ADSCs.Conclusions: Local injection of ADSCs in a rat model of urethral fibrosis significantly decreased collagen type I and III. These findings suggest that ADSC injection may prevent scar formation and potentially serve as an adjunct treatment to increase the success rate of primary treatment for urethral stricture disease. Further animal and clinical studies are needed to confirm these results.
Facebook Tops 500 Million Users; Life by the Numbers?
Authors: Lancaster Ron
Published: May 2016

Students analyze items from the media to answer mathematical questions related to the article. This month's clips deal with the growth of Facebook and a geometric algebra problem that appeared in an obituary for George Lenchner, founder of the Math Olympiads. The mathematics involved in these clips includes scientific notation, proportional reasoning, exponents, exponential growth, and quadratic equations.
Student-Generated Questions in Mathematics Teaching
Authors: Foster Colin
Published: May 2016

Exploring even something as simple as a straight-line graph leads to various mathematical possibilities that students can uncover through their own questions.
NMR analysis on the sialic acid‐binding mechanism of an R‐type lectin mutant by natural evolution‐mimicry
Authors: Hemmi Hikaru , Kuno Atsushi , Unno Sachiko , Hirabayashi Jun
Published: May 2016

A sialic acid‐binding lectin (SRC) was created from the C‐terminal domain of an R‐type N‐acetyl lactosamine‐binding lectin (EW29Ch) by natural evolution‐mimicry. Here, we clarified its sialic acid‐binding mechanism using NMR spectroscopy. The NMR analysis showed differences between conformations of the 6′‐sialyllactose‐bound SRC in the solution state and that in the crystal state, and differences between the internal motion of the loop region in subdomain γ in SRC and that of the corresponding region in EW29Ch. The NMR analysis thus provided useful information to explain the manner of binding to 6′‐sialyllactose in solution, which the previous X‐ray crystal structure analysis lacked.
The catalytic power of magnesium chelatase: a benchmark for the AAA+ATPases
Authors: Adams Nathan B. P. , Brindley Amanda A. , Hunter C. Neil , Reid James D.
Published: May 2016

In the first committed reaction of chlorophyll biosynthesis, magnesium chelatase couples ATP hydrolysis to the thermodynamically unfavorable Mg2+ insertion into protoporphyrin IX (ΔG°′ of circa 25–33 kJ·mol−1). We explored the thermodynamic constraints on magnesium chelatase and demonstrate the effect of nucleotide hydrolysis on both the reaction kinetics and thermodynamics. The enzyme produces a significant rate enhancement (kcat/kuncat of 400 × 106 m) and a catalytic rate enhancement, , of 30 × 1015 m−1, increasing to 300 × 1015 m−1 with the activator protein Gun4. This is the first demonstration of the thermodynamic benefit of ATP hydrolysis in the AAA+ family.
A survey of superthermal electron flux depressions, or “electron holes,” within the illuminated Martian induced magnetosphere
Authors: Hall B. E. S. , Lester M. , Nichols J. D. , Sánchez‐Cano B. , Andrews D. J. , Opgenoorth H. J. , Fränz M.
Published: May 2016

Since Mars lacks a global intrinsic magnetic field, the solar wind interacts directly with the Martian upper atmosphere and ionosphere. The presence of localized intense remnant crustal magnetic fields adds to this interaction, making the Martian plasma system a unique environment within the solar system. Rapid reductions in the electron flux, referred to as “electron holes,” occur within the Martian induced magnetosphere (IM). We present a statistical analysis of this phenomenon identified from proxy measurements of the electron flux derived from measurements by the Analyser of Space Plasmas and Energetic Neutral Atoms Electron Spectrometer experiment on board the Mars Express (MEX) spacecraft. The study is completed for the period of 9 February 2004 to 9 May 2014. Electron holes are observed within the IM in more than 56% of MEX orbits during this study period, occurring predominantly at altitudes less than 1300 km, with the majority in the negative X Mars‐Centric Solar Orbital direction. The spatial distribution above the surface of Mars is observed to bear close resemblance to that of the crustal magnetic fields as predicted by the Cain et al. [] magnetic field model, suggesting that they play an important role in the formation of these phenomena.