bluuebunny/crossref_metadata_2025 huggingface dataset:
Satellite observations of changes in snow-covered land surface albedo during spring in the Northern Hemisphere
Authors: Atlaskina K. , Berninger F. , de Leeuw G.
Published: September 2015

Abstract. Thirteen years of Moderate Resolution Imaging Spectroradiometer (MODIS) surface albedo data for the Northern Hemisphere during the spring months (March–May) were analyzed to determine temporal and spatial changes over snow-covered land surfaces. Tendencies in land surface albedo change north of 50° N were analyzed using data on snow cover fraction, air temperature, vegetation index and precipitation. To this end, the study domain was divided into six smaller areas, based on their geographical position and climate similarity. Strong differences were observed between these areas. As expected, snow cover fraction (SCF) has a strong influence on the albedo in the study area and can explain 56 % of variation of albedo in March, 76 % in April and 92 % in May. Therefore the effects of other parameters were investigated only for areas with 100 % SCF. The second largest driver for snow-covered land surface albedo changes is the air temperature when it exceeds a value between −15 and −10 °C, depending on the region. At monthly mean air temperatures below this value no albedo changes are observed. The Enhanced Vegetation Index (EVI) and precipitation amount and frequency were independently examined as possible candidates to explain observed changes in albedo for areas with 100 % SCF. Amount and frequency of precipitation were identified to influence the albedo over some areas in Eurasia and North America, but no clear effects were observed in other areas. EVI is positively correlated with albedo in Chukotka Peninsula and negatively in eastern Siberia. For other regions the spatial variability of the correlation fields is too high to reach any conclusions.
CryoSat-2 delivers monthly and inter-annual surface elevation change for Arctic ice caps
Authors: Gray L. , Burgess D. , Copland L. , Demuth M. N. , Dunse T. , Langley K. , Schuler T. V.
Published: September 2015

Abstract. We show that the CryoSat-2 radar altimeter can provide useful estimates of surface elevation change on a variety of Arctic ice caps, on both monthly and yearly timescales. Changing conditions, however, can lead to a varying bias between the elevation estimated from the radar altimeter and the physical surface due to changes in the ratio of subsurface to surface backscatter. Under melting conditions the radar returns are predominantly from the surface so that if surface melt is extensive across the ice cap estimates of summer elevation loss can be made with the frequent coverage provided by CryoSat-2. For example, the average summer elevation decreases on the Barnes Ice Cap, Baffin Island, Canada were 2.05 ± 0.36 m (2011), 2.55 ± 0.32 m (2012), 1.38 ± 0.40 m (2013) and 1.44 ± 0.37 m (2014), losses which were not balanced by the winter snow accumulation. As winter-to-winter conditions were similar, the net elevation losses were 1.0 ± 0.20 m (winter 2010/11 to winter 2011/12), 1.39 ± 0.20 m (2011/12 to 2012/13) and 0.36 ± 0.20 m (2012/13 to 2013/14); for a total surface elevation loss of 2.75 ± 0.20 m over this 3-year period. In contrast, the uncertainty in height change from Devon Ice Cap, Canada, and Austfonna, Svalbard, can be up to twice as large because of the presence of firn and the possibility of a varying bias between the true surface and the detected elevation due to changing year-to-year conditions. Nevertheless, the surface elevation change estimates from CryoSat for both ice caps are consistent with field and meteorological measurements.
The Comparative Impact of Reading Comprehension and Translation Practices on EFL Learners’ Grammar Achievement
Authors: Akef Kourosh , Kherad Ranjbar Maryam
Published: September 2015

This study focused on the comparative impact of teaching reading comprehension and translation practice on EFL learners’ grammar achievement since previous studies have not directly dealt with the respective subject. In this study the total number of learners was 60 students attending in Poyandegan Rahe Kish institute. The current study utilized quantitative research methods to explore the implications of reading comprehension and translation by comparing their success rates in terms of grammar. Sixty participants out of 120 after going through a proficiency test for homogenization and a pilot test on the grammar questionnaire were divided into two experimental groups receiving instruction on reading comprehension in one group and translation in another each in 12 sessions (two sessions dedicated for pre and post test). At the end of the treatment, sample TOEFL grammar questionnaires were administered to both groups. To test the hypothesis, a T-test was employed concluding that the participants who received translation instruction and reading comprehension on grammar achievement. The analysis of data using an independent sample t-test indicated significant difference between the performances of experimental groups. The respective conclusion was that translation had a significant effect on EFL learners’ grammar achievement.
Exploring Attitudes towards a Randomised Controlled Trial of Venous access Devices – a Nested Pre-trial Qualitative Study
Authors: Ritchie Moira , Kelly Linda J. , Moss Jonathan , Paul James , Shaw Rebecca
Published: September 2015

Purpose

This pre-trial qualitative research study was carried out to explore patient and clinical staff attitudes to central venous access devices (CVADs). In addition, views about participation in a randomised controlled trial (RCT) were explored with the aim of maximising recruitment to an imminent RCT of three CVADs.

Methods

Three patient focus groups (each comprising three patients) and 23 interviews with clinical staff were conducted. Interviews and focus group discussions were digitally recorded, transcribed verbatim, anonymised, uploaded to the QSR NVivo10 qualitative software programme and thematically analysed.

Results

Analysis of focus group interviews revealed the added challenges that a CVAD poses to patients with cancer. Four key themes emerged: continuity of daily life, pain and discomfort, stigma (a mark of disgrace associated with certain conditions) and self-preservation. The findings show the impact of a CVAD on patients’ ability to manage their condition. Clinical staff interviews highlighted several potential barriers to recruitment; a lack of equipoise (genuine clinical uncertainty as to which intervention is the most beneficial), concerns about the logistics of device insertion and a perceived requirement for education and training.

Conclusions

This qualitative study raises awareness of key areas of concern to patients who need a CVAD for chemotherapy delivery. It was identified that there is a need for clearer patient information around CVADs. Additionally it allows investigators to identify barriers to recruitment in a timely manner in order to minimise the potential for conflict between the roles of carer and researcher and consequently, maximise recruitment to the RCT.
Novel Approach to Percutaneous Thrombolysis in Large Caliber Clotted Vascular Access Using Ultrasound-accelerated Thrombolysis
Authors: Zagory Jessica A. , Perkowski Paul E. , Guidry London C. , Schellack Jon V.
Published: September 2015

Purpose

End-stage renal disease has a high cost burden to the public. Surgical procedures such as hemodialysis (HD) access creation and transplant have high rates of vascular access complications, infections, and readmissions. Cost of HD care has increased to $19.4 billion in 2011; 30-day readmission rates are as high as 36%. There is a continuing need to preserve the route of vascular access for patients, given frequent thrombosis at a rate of 0.8 episodes per patient year at risk. We describe a novel method of thrombolysis using ultrasound-accelerated thrombolysis (USAT) technology for large caliber clotted vascular access.

Methods

Consecutive patients with thrombosis of their dialysis vascular access that involved large caliber conduits or those that extended into large and/or central veins (axillary, subclavian, innominate) were chosen to undergo catheter-directed thrombolysis with the EKOS EndoWave system.

Results

Twelve patients underwent a total of 14 procedures. Complete thrombolysis was achieved after seven procedures at the time of repeat fistulogram. Four patients required percutaneous balloon thombectomy to resolve remaining clot at the arterial anastomosis, and three required rheolytic thrombectomy in the aneurysmal segment of the arteriovenous fistula (AVF). All patients had an associated procedure (percutaneous transluminal angioplasty and/or stent placement) to treat the cause of thrombosis.

Conclusions

USAT is a safe and effective percutaneous method of thrombolysis in patients who have large clot burden.
The S-Tunnel for Tunnelled Dialysis Catheter: An Alternative Approach to the Prevention of Displacement
Authors: Jenkins Glyndwr W. , Kelly Michael , Anwar Siddiq , Ahmed Saeed S.
Published: September 2015

Purpose

Vascular access has been described in the literature anywhere from the ‘Achilles Heel’ to the ‘Cornerstone’ of haemodialysis. Displacement of a central venous catheter is not an uncommon occurrence. We discuss an alternative method of placement for the tunnelled central venous catheter to prevent displacement in those patients with excess anterior chest wall soft tissue.

Methods

A new surgical technique for placement of a tunnelled central venous catheter was developed in an attempt to reduce the number of displacements. This involved the creation of a second tunnel at a 90° angle to the original retrograde tunnelled path.

Results

The authors have currently placed five ‘S-Line’ tunnelled central venous catheters with no reports of displacement or line infection over a period of 18 months.

Conclusions

The ‘S-Line’ offers a simple, straightforward and most importantly safe method to reduce the incidence of tunnelled right internal jugular central venous catheter displacement.
The Economic Issue of Vascular Access within the Japanese Medical Reimbursement System
Authors: Takemoto Yoshiaki , Naganuma Toshihide
Published: September 2015

We analyzed the current health economics of vascular access (VA) procedures in Japan. Results showed that the yearly VA-related medical expenses were as high as JPY20 billion and accounted for 1.4% of the total healthcare cost for chronic renal failure. The United States Renal Data System (USRDS) statistics showed that in the USA the yearly VA-related medical expenses accounted for 1.2% of the total medical cost for chronic renal failure, indicating that the costs did not differ much between the two countries. Moreover, percutaneous transluminal angioplasty (PTA) accounts for approximately 60% of VA procedures performed in Japan, and this ratio is increasing every year. Due to the aging of society and longer treatment periods, it is thought that PTA will become a significant procedure for the treatment of chronic renal failure in Japan.
Starting Hemodialysis with Catheter and Mortality Risk: Persistent Association in a Competing Risk Analysis
Authors: Roca-Tey Ramon , Arcos Emma , Comas Jordi , Cao Higini , Tort Jaume
Published: September 2015

Purpose

The vascular access (VA) used at hemodialysis (HD) inception is involved in the mortality risk. We analyzed the survival of incident patients over time according to the initial VA and the VA profile of patients who died during the first year of follow-up.

Methods

Data of VA were obtained from 9956 incident HD patients from the Catalan Registry.

Results

Over 12 years, 47.9% of patients initiated HD with a fístula, 1.2% with a graft, 15.9% with a tunneled catheter and 35% with an untunneled catheter. Regarding fistula use, the hazard ratio of death for all-causes over time when applying a multivariate competing risk model was 1.55 [95% confidence interval (CI): 1.42-1.69] and 1.43 (95% CI: 1.33-1.54) for patients with tunneled and untunneled catheter, respectively. During the first year of follow-up, the crude all-cause mortality rate (deaths/100 patient-years) was higher during the early (first 120 days) compared to the late (121-365 days) period: 18.3 (95% CI: 16.8-19.8) versus 15.4 (95% CI: 14.5-16.5). Regarding fistula use, for patients using untunneled and tunneled catheter, the odds ratio of death in the early period for all-causes was 3.66 (95% CI: 2.80-4.81) and 2.97 (95% CI: 2.17-4.06), for cardiovascular causes it was 2.76 (95% CI: 1.90-4.01) and 1.84 (95% CI: 1.17-2.89) and for infection-related causes it was 6.62 (95% CI: 3.11-14.05) and 4.58 (95% CI: 2.00-10.52), respectively.

Conclusions

Half of all incident patients in Catalonia are exposed to excessive mortality risk related to catheter and this scenario can be improved by early fistula placement.
PROPRIEDADES FÍSICAS E HIDROLÓGICAS DOS SOLOS E OS ESCORREGAMENTOS RASOS NA SERRA DO MAR PAULISTA
Authors: Vieira Bianca Carvalho , Ferreira Fabiana Souza , Gomes Maria Carolina Villaça
Published: September 2015

O objetivo deste trabalho foi determinar a influência de algumas propriedades físicas e hidrológicas do solo na deflagração dos escorregamentos translacionais rasos na Serra do Mar (SP). Foram selecionadas três cicatrizes de escorregamentos rasos deflagrados durante o evento de 1967, nas quais foram coletadas amostras em três pontos (lateral, superior e interior) e em diferentes profundidades, sendo analisadas as seguintes propriedades: granulometria, porosidade, coesão, ângulo de atrito interno e condutividade hidráulica saturada. Os resultados mostraram altos valores de areia e baixos percentuais de argila, com reduzidos índices de atividade. Os valores de coesão variaram entre 0kPa e 11kPa e o ângulo de atrito interno entre 25,8º e 36,8º. A condutividade hidráulica saturada apresentou pequena variabilidade, mas significativas descontinuidades entre 1 e 2,5 m de profundidade. Acredita-se que este estudo possa fornecer informações para definição de locais e profundidades para o monitoramento hidrológico em tempo real, contribuindo para o entendimento e para a previsão dos escorregamentos rasos na Serra do Mar.
Judéens et chrétiens : « rupture », « séparation », « distanciation » ?
Authors: Bélanger Steeve
Published: September 2015

Depuis le xixe siècle, la question de la « séparation » entre le « judaïsme » et le « christianisme » anciens a soulevé de nombreux débats entre spécialistes. Pour tenter d’expliquer ce phénomène historique complexe, les chercheurs n’ont pas hésité à recourir à de nombreuses métaphores et à divers paradigmes interprétatifs. Or, la recherche des trois dernières décennies a contribué à renouveler et à nuancer notre connaissance du « judaïsme » et du « christianisme » anciens obligeant alors à revoir les métaphores et paradigmes par lesquels on a tenté d’expliquer la « séparation » entre ces deux entités religieuses.
L’urbanisation de la campagne. Motifs et options du régime québécois de protection du territoire agricole
Authors: Côté Michel , Mercier Guy , Roy Francis
Published: September 2015

Au Québec, l’urbanisation continue à gagner sur la campagne. Le phénomène se poursuit en dépit de la condamnation dont il fait l’objet et des mesures prises à son encontre. Divers arguments sont avancés pour expliquer ce paradoxe : complaisance de la classe politique, laxisme des administrations territoriales, efficacité en sous-main de divers groupes de pression. L’affaire est toutefois d’un autre ressort. En fait, lois et règlements ménagent clairement des possibilités de poursuivre l’urbanisation diffuse, y encouragent même parfois, par-delà les dénégations de principe. Faut-il y voir une regrettable inadvertance ? L’analyse montre que cette pratique obéit plutôt à un désir dont l’assise culturelle est tellement forte qu’il transcende toute norme devant, en principe, s’y opposer.
S’installer, habiter et voisiner à Montlouis-sur-Loire. Territorialisation des classes moyennes dans une petite ville périurbaine tourangelle
Authors: Semmoud Noria , Amalric Marion , Florin Bénédicte , Stadnicki Roman , Troin Florence
Published: September 2015

Cet article porte sur les formes de territorialisation de la fraction moyenne des couches moyennes de population dans la ZAC des Terrasses-de-Bodets, à Montlouis-sur-Loire, une petite ville inscrite dans le périurbain tourangeau. Nous proposons d’étudier le périurbain à travers les valeurs résidentielles qui caractérisent ces catégories sociales, en considérant que l’intérêt de cet exemple se trouve dans la politique d’aménagement municipale, volontariste et imprégnée des normes de développement durable et de mixité sociale. Si les 42 entretiens semi-directifs menés pour cette étude confirment les résultats de travaux antérieurs sur les aspirations des populations périurbaines autour du triptyque tiers-espace / propriété / pavillon, ils mettent également en évidence une forte demande de proximité (proximité de Tours, des centralités, des espaces de loisir, etc.) qui devient ainsi une valeur résidentielle essentielle, ainsi qu’une sociabilité de voisinage qui donne tout son sens au « quartier ». Cette réflexion permet d’approfondir la connaissance des couches moyennes à partir de leurs désirs en matière d’habiter, mais elle permet aussi de contribuer aux réflexions sur les différenciations des espaces périurbains et leur hétérogénéité sociale.
Muñequitos rusos: la nostalgia y su contexto en la diáspora cubana
Authors: Darias Alfonso Iván
Published: September 2015

Resumen: El presente artículo examina la importancia de la influencia soviética en la Cuba revolucionaria como incentivo para la vinculación afectiva transnacional entre emigrados cubanos, a través del análisis de las entradas e interacciones del blog Muñequitos Rusos, creado con el propósito de rescatar parte de la memoria colectiva de ese período reciente en la historia de la isla. Mi argumentación se enfoca al consumo y producción de “memorias mediáticas” en la diáspora, un espacio complejo que se caracteriza por la tensión que ejercen el país de origen y el de adopción, en la vida cotidiana de los emigrados y en sus constantes intentos por definir sus lealtades e identidad. Parto de que en este contexto, el pasado adquiere una importancia primordial como centro hacia el cual dirigir las nociones de pertenencia que influyen además en la formación de identidades. En mi opinión tales interacciones asociadas con los muñequitos, como síntesis emocional de un período más complejo e influyente, repercute en las estrategias personales mediante las cuales los emigrados cubanos construyen sus nociones de identidad y sobre todo para, desde la diáspora, revisar y elaborar sus propias nociones sobre el pasado común en su país de origen.       Abstract: This articles discusses the importance of the Soviet influence in revolutionary Cuba as an incentive for transnational bonding amongst Cuban emigrants, by analysing the posts and interactions in the blog Muñequitos Rusos (Russian cartoons), created with the aim of recovering part of the collective memory of that recent period in the history of the Caribbean island. My argument focuses on the consumption and production of “mediated memories” in the context of diaspora a complex space characterised by the tension of the homeland and the host country in the emigrants’ everyday life and in their constant attempts to define their loyalties and identity. I start from the premise that in this context, the past acquires a vital importance, as a centre to which address notions of belonging, which also influences identity formation. I argue that such interactions associated with the cartoons, as an emotional summary for a more complex and influential period, affects the ways in which Cuban émigrés construct their notions of identity and, above all, revise and elaborate in diaspora their own notions about the common past in the homeland.   Keywords: Russian Cartoons, Blogs, Collective Memory, Cuban diaspora, Cuba, USSR.
CURRENT APPROACHES TO ORTHOGRAPHY INSTRUCTION FOR SPANISH HERITAGE LEARNERS: AN ANALYSIS OF INTERMEDIATE AND ADVANCED TEXTBOOKS
Authors: Burgo Clara
Published: September 2015

As it is well known, heritage learners of Spanish have an advantage on oral production and aural comprehension over L2 learners. However, due to their lack of formal instruction in Spanish, their linguistic weaknesses lie on their literacy skills (reading and writing). In terms of writing skills, students mainly struggle with orthography issues (accentuation and spelling) and larger literacy skills (e.g. developing a thesis or organizing ideas). However, there is an important gap in the literature regarding orthographic acquisition since most of the research in the field on focus on form instruction has predominantly been on grammar acquisition (Anderson, 2008; Montrul and Bowles, 2008; Potowski, 2005, among others). In fact, despite the increasing amount of textbooks addressed to this student population with an emphasis on the writing process, to my knowledge there has not been a study on the current approaches of Spanish heritage learners’ textbooks for orthography instruction. After analyzing four popular textbooks for Spanish heritage, it can be deduced that the lack of research on this area perpetuates the maintenance of traditional non-communicative explicit instruction of orthography through drills after an explicit explanation of the rules of both accentuation and spelling but new textbooks shed some light towards the implementation of focus on form teaching techniques commonly used in the L2 classroom such as input-output activities.
IDEOLOGÍA Y MOVIMIENTOS CULTURALES: UNA NOTA SOBRE SU INFLUENCIA EN LA ACTIVIDAD LINGÜÍSTICA
Authors: Fábregas Antonio
Published: September 2015

Una vista de pájaro sobre los movimientos culturales en Latinoamérica y su recepción en España nos muestra que se fue pasando progresivamente de cierta preconcepción de que las naciones hispanohablantes de América debían necesariamente aceptar la supremacía cultural de España, fundada en su precedencia histórica, hasta un planteamiento más policéntrico en el que, poco a poco, se iba aceptando la autonomía de las naciones americanas, hasta culminar en el concepto de panhispanismo, que es estándar en nuestros días, al menos sobre el papel. El objetivo de este trabajo es hacer una cala en esta evolución cultural y mostrar cómo se refleja en dos aspectos del estudio de la lengua: el diccionario y la gramática. Más en particular, exploraremos cómo la actividad lingüística de la Real Academia Española y la Asociación de Academias durante el siglo XX y los comienzos del XXI siguió un desarrollo que replica estos cambios culturales, pivotando sobre todo en los conceptos de unidad, diversidad y panhispanismo, que han sido centrales en la historia cultural reciente de Latinoamérica.
DE LA FONÉTICA DEL HABLA ESPONTÁNEA A LA FONOLOGÍA DE LA COMPLEJIDAD
Authors: Cantero Serena Francisco José
Published: September 2015

El análisis fonético del habla espontánea nos enfrenta a numerosos interrogantes sobre la naturaleza de los sonidos del habla, así como sobre su interpretación fonológica. En este artículo revisamos algunos de esos interrogantes, así como sus implicaciones teóricas y prácticas, y proponemos un enfoque alternativo, basado en la teoría de la competencia comunicativa y en los principios del pensamiento complejo.
¿Qué tiene que ver la fonética con la práctica clínica y logopédica? Algunos ejemplos de colaboración interdisciplinar
Authors: Fernández Planas Ana María
Published: September 2015

El lenguaje es nuestra herramienta fundamental de comunicación. Los lingüistas debemos ocuparnos de su estudio tanto en su uso recto como en aquellas manifestaciones alteradas o deficitarias. Concretamente, los fonetistas debemos aplicar el conocimiento teórico que tenemos de la producción (fonación o articulación), la transmisión y la percepción de los sonidos al ámbito clínico en sentido amplio, incluidos los cambios evolutivos en el proceso de adquisición. Esta dimensión de la fonética (junto con la fonología) redundará: 1) en la consecución de un mayor conocimiento teórico del ámbito fónico; y 2) en la ayuda a personas que sufren en nuestra sociedad por causas que afectan al lenguaje, especialmente al habla, incluso de forma preventiva.
Las pausas sonoras y los alargamientos en español: un estudio preliminar
Authors: Machuca María Jesús , Llisterri Joaquim , Ríos Antonio
Published: September 2015

Aunque los fenómenos de hesitación en el discurso –pausas sonoras y alargamientos– se han abordado desde diferentes puntos de vista, son escasos los estudios que analizan sus manifestaciones acústicas en español. En este trabajo se presenta una caracterización preliminar de las hesitaciones que, generalmente, suelen aparecer en el habla espontánea con diferentes funciones discursivas. Se han analizado 180 minutos de conversaciones en las que han participado seis hablantes, con una duración aproximada de 30 minutos cada una, y 30 fragmentos de producción espontánea de un minuto de duración correspondientes a tres sesiones de grabación de 10 locutores. En las primeras se da una interacción entre los participantes, mientras que en las segundas, el hablante sabe que no será interrumpido durante su intervención. El análisis acústico se ha complementado con un estudio perceptivo en el que los oyentes debían valorar la naturalidad y la espontaneidad de los mismos fragmentos presentados con o sin alargamiento y con o sin pausa sonora. Los resultados muestran, en primer lugar, que la pausa sonora más frecuente en español es [e?]. Los valores medios y las desviaciones correspondientes a la duración de los alargamientos y de las pausas sonoras no arrojan diferencias significativas entre estas hesitaciones. No obstante, el rango de los valores medios debería considerarse en la caracterización de tales elementos. Además, los resultados indican que el hecho de que el hablante sepa que no va a ser interrumpido conlleva un incremento de la aparición de hesitaciones en habla espontánea. Los enunciados con pausas y alargamientos se perciben con el mismo grado de naturalidad si se comparan con una versión de los mismos enunciados en la que se han eliminado las hesitaciones, pero no con idéntico nivel de espontaneidad. Finalmente, cabe resaltar que los alargamientos suelen percibirse en el discurso como si el hablante hubiera realizado un silencio.
Hacia una prosodia basada en el uso: actos de habla en el español mexicano
Authors: Martín Butragueño Pedro
Published: September 2015

El trabajo muestra algunas aportaciones del estudio de la prosodia basado en el uso lingüístico. Esta prosodia se basa en entrevistas cara a cara, muestras representativas en diferentes comunidades, habla despreocupada, una visión constructiva de los procesos lingüísticos, datos analizados en contexto, etc. Permite la generación de hipótesis sobre el desarrollo lingüístico, el cambio y la variación y en general un análisis de corte más realista. A este propósito, se comparan enunciados aseverativos y directivos desde un punto de vista regulativo, y también se estudian enunciados expresivos desde una perspectiva constitutiva. Los datos se representan en términos de la llamada teoría de optimidad estocástica.
Otolith Sr:Ca ratio and morphometry as indicators of habitat of a euryhaline species: The case of the silverside Odontesthes bonariensis
Authors: Avigliano Esteban , Villatarco Paola , Volpedo Alejandra V
Published: September 2015

The silverside Odontesthes bonariensis is a euryhaline species native of South America and represents a very important fishing resource for the Plata Basin (Argentina and Uruguay). This study compares the Sr:Ca ratio of water as well as the Sr:Ca ratio and morphometry of the sagittal otolith of the silverside present in different environments (one salt lake, two freshwater dams, one lagoon, and one estuary) in order to evaluate the use of these variables as markers of habitat. The pattern of the Sr:Ca ratio in the water agrees with the one found in the otoliths, showing a positive relationship with the conductivity of the water. Univariate and multivariate analyses of variance indicated significant differences (P < 0.05) among the localities studied for the morphometric indices. The discriminant function analysis provided a high percentage of correctly classified individuals for the saltwater environment (100%) and the lentic water bodies and estuary (60–80%), circularity and form factor being the most relevant morphometric variables. These results indicate that the Sr:Ca ratio and otolith morphometry are good markers of habitat for this important resource.
Growth, ammonium excretion, and oxygen consumption of hybrid red tilapia (Oreochromis mossambicus × Oreochromis aureus) grown in seawater and freshwater
Authors: Barreto-Curiel Fernando , Durazo Eduardo , Viana María Teresa
Published: September 2015

In a comparative study using the hybrid tilapia Oreochromis mossambicus × Oreochromis aureus grown in seawater and freshwater, no significant differences in growth performance (weight gain) and biological indices (e.g., feed conversion efficiency and survival) was observed after 90 days of experimentation. A common feed was formulated to contain 40% crude protein and 8.5% crude fat. Fish meal and poultry by-product meal (50:50) were used as a source of protein in the formulation. The study was conducted using recirculation systems and organisms already adapted to seawater and freshwater with an initial weight of 25.0 ± 0.06 g and 24.70 ± 0.32 g, respectively (four replicates per treatment); at the end of the experiment their final weight was 161.80 ± 12.78 g and 167.60 ± 7.29 g, respectively. The thermal growth coefficient was 0.91 and 0.89 (seawater vs freshwater), and there were no significant differences; however, the apparent digestibility of dry matter as well as per nutrient (protein, lipid, and carbohydrate) was significantly higher for the organisms in the seawater treatment. The digestibility could be associated with greater enzymatic activity in the presence of higher ionic strength. The respirometric study indicated that the O:N ratios were similar for organisms reared in seawater and freshwater, with values of 21 and 18, respectively. This indicates that this strain of tilapia uses a mixture of proteins and lipids as energy substrates. We conclude that this strain of tilapia has the potential to adapt and thrive in a marine environment and that its production practices could be expanded.
Cell Culture Technology
Authors: Karkare Subhash
Published: September 2015

Cell culture processes, the
in vitro
growth of animal, insect, or plant cells on a large scale to manufacture biochemicals or cells for therapeutic purposes, have evolved and grown significantly over the past 10 years. Significant growth in this technology, primarily because of the advent of recombinant DNA methods for the production of therapeutic proteins and hybridoma technology for the production of monoclonal antibodies, occurred in the late 1980s and 1990s. During the past decade, many developments have led to increased process efficiencies and much higher product titers and made this technology ubiquitous in the biopharmaceutical industry. Today, worldwide products of cell culture technology command revenues of more than $60 billion per year. Additionally, the advent of stem cells and regenerative medicine has ushered in the need for novel methods of cell culture that are propelling the industry in new directions such as the use of single‐use bioreactors for personalized medicine. Single‐use bioreactor technology is also finding use in large‐scale production of protein therapeutics. This article provides information on the various processes and equipment used in the production of monoclonal antibodies (MAbs), recombinant therapeutics, vaccines, and other products.
Electroanalytical Techniques
Authors: Sandifer, Consultant James R.
Published: September 2015

Electroanalytical techniques may be classified as involving active or passive measurements. Active measurements, such as those obtained in coulometry and voltammetry, result from the application of a voltage or current. Passive measurements, such as those from an ion‐selective electrode, are made independently of external waveforms. The various electroanalytical techniques are described, as is the assembly of electrochemical cells for electroanalysis. Electroanalytical cells employ at least two electrodes placed in either aqueous or organic media. Analyte concentrations may be in the picomolar to molar range. Electroanalytical systems may be employed independently or in conjunction with a separation technique such as chromatography.
Fiber Optics
Authors: Kosinski Sandra , MacChesney John B. , Udd Eric
Published: September 2015

In this article, the principles of light guidance within a fiber and fiber fabrication methods are presented. Fiber‐optic sensors that are particularly useful for smart structures, and their applications, are also discussed.

Fiber‐optic‐based communication depends on the availability of high quality low loss optical fibers. Operating wavelengths of fibers have been extended by controlling fiber attenuation and dispersion. The use of high purity starting materials and vapor deposition techniques allows the production of glass fibers having optical losses that approach the intrinsic loss of silica. Active optical fibers have been exploited to amplify light, thereby extending the range of transmission systems and increasing capacity. Erbium‐doped fibers are being used for signal amplification in fiber‐optic cable. Devices taking advantage of gratings written in optical fibers include filters and lasers.

Applications of fiber‐optic sensors for smart structures fall into one of the four major categories: (1) sensors—monitoring such parameters as temperature, pressure, viscosity, degree of cure, and residual strain; (2) nondestructive testing—measuring acoustic signatures, changes in strain profiles, delamination, and other changes in the structural characteristics of fabricated parts; (3) condition and damage assessment systems—monitoring the overall condition of the structure; and (4) control—fiber‐optic smart structures may be used to support control systems.
Ethylene Polymers,HDPE
Authors: McDaniel Max P. , DesLauriers Paul J.
Published: September 2015

High density polyethylene (HDPE) is the most widely used type of polyethylene. It was invented in the early 1950s and commercial catalytic processes were quickly developed based on three different transition metals: Cr, Mo, and Ti. Development of many different grades of HDPE followed, which are currently manufactured by various commercial processes.

The molecular structure of HDPE vary widely to produce polymers of various molecular weight, molecular weight distribution, end group composition, and other characteristics, which in turn, affect properties such as stiffness of the polymer, the gloss or clarity, tear resistance, chemical resistance, and electrical insulation properties. The low melting point and high chemical stability of HDPE facilitate its processing by many conventional techniques, including injection molding, blow molding, and blown and cast film.

Common uses for HDPE include food packaging, bottles, bags, medical applications, drums, fuel tanks and other automotive parts, pipe, toys, film, and fiber and many specialized applications, eg, in prosthetic devices, and hip or knee joint replacements.
Olefin Polymers, Introduction
Authors: Kissin Yury V.
Published: September 2015

Polyolefin resins are a large family of semicrystalline and amorphous polymers and copolymers used as commodity plastics, engineering plastics, and elastomers. Industry produces a broad variety of polyolefin resins. They differ in chemical structure, molecular weight, stereoregularity, and the crystallinity degree.

Polyolefin resins are manufactured by a number of technological processes. The latter include polymerization reactions with radical initiators in supercritical ethylene at 150–350°C and a variety of catalytic polymerization processes in hydrocarbon slurry, in a neat monomer, in solution, and in the gas phase. All the processes use three types of catalysts: Ziegler–Natta catalysts, chromium oxide catalysts, and metallocene catalysts.

Polyolefin resins enjoy a large range of applications as commodity resins, such as engineering plastics, elastomers, synthetic rubbers, and specialty polymers. These applications include film, coatings, wire insulation, household and industrial containers, pipe and tubing of various types, and components of engineering articles. Because of their versatility, polyolefin resins have become the largest commercially manufactured polymer products in the world, ∼150 × 10
6
metric tons·yr
−1
in 2013, which corresponds to over 50% of the total production of all plastic materials.
Lasers
Authors: Csele Mark
Published: September 2015

This article covers the fundamentals of lasers. Beginning with the nature of laser light itself, the mechanism of the laser is examined including basic rate equations. Gain and loss in a laser are analyzed and the laser cavity itself is modeled as an interferometer. Techniques of nonlinear harmonic generation as well as fast‐pulse production (Q‐switching) are examined. Finally an overview of the most common commercial lasers, including gas, solid‐state, and semiconductor types is provided. For each type of laser, output characteristics are examined as well as the specific mechanism of each.
Polyethylene, Linear Low Density
Authors: Kissin Yury V.
Published: September 2015

Linear low density polyethylene (LLDPE) resins are copolymers of ethylene and α‐olefins with a low α‐olefin content; their density ranges from 0.915 to 0.925 g cm
−3
. These resins are semicrystalline materials that are produced in catalytic copolymerization reactions. Various types of LLDPE resins differ in several respects: (a) the type of the α‐olefin used in copolymerization with ethylene (1‐butene, 1‐hexene, 4‐methyl‐1‐pentene, or 1‐octene); (b) the content of the α‐olefin in the copolymers (between 2.0 and 3.5 mol%); (c) density and crystallinity degree; and (d) compositional uniformity of the copolymers.

LLDPE resins are produced in industry with three classes of catalysts: Ziegler catalysts based on titanium compounds, catalysts utilizing metallocene complexes, and Phillips catalysts based on chromium oxides. The resins are manufactured on a commercial scale in three types of polymerization processes: in the gas phase, in solution, and in slurry.

LLDPE resins are major commodity products with a combined 2012 worldwide manufacture volume exceeding 26 × 10
6
 ton yr
−1
. Film is their largest application market. It is used to manufacture grocery sacks, bags for produce, trash bags, and bags for merchandise packaging, garments, etc, as well as for non‐packaging applications such as industrial sheeting and agricultural mulch film. Injection molding products represent the second largest market for LLDPE resins; they are mostly used for housewares. These resins are also used for blow molding of bottles and drums; for rotational molding of toys, large containers, and tanks; for manufacture of pipe and tubing; and for wire coating in electrical and telephone industry.
Lubrication and Lubricants
Authors: Gresham Robert M. , Canter Neil M. , Zabawski Evan S. , Zou Min
Published: September 2015

Lubrication is a process in which a lubricant is placed between rubbing surfaces to control friction and reduce wear. This article outlines the nature of the frictional force, the wear process, the role of surface characteristics, and the mechanisms of lubrication. The manufacture and classification of lubricating oil base stocks, including refined petroleum stocks, chemical base stocks, stocks synthesized from other chemicals, and vegetable oils, are covered. The composition and function of lube oil additives are described for enhancing oxidation stability, corrosion resistance, wear reduction, friction modifying, viscosity–temperature characteristics, and other important performance characteristics. The performance characteristics of lubricating oils for selected applications are discussed, including automotive engine oils, diesel engine oils, automatic transmission fluids, automotive gear oils, jet engine lubes, and industrial turbine oils. Metalworking fluids, lubricating grease, solid‐film lubricants, and lubrication in extreme environments are covered, as are the lubricants market and environmental and health concerns.
Macrolide Antibiotics
Authors: Kirst Herbert A.
Published: September 2015

Macrolide antibiotics are one of the larger classes of fermentation‐derived natural products. In addition, many semisynthetic derivatives have been synthesized. They treat infections caused by most Gram‐positive bacteria, some susceptible Gram‐negative bacteria, and atypical bacteria such asMycoplasma pneumoniaeandLegionella pneumophila. They are orally bioavailable and accumulate in tissues and organs. They are regarded as one of the safest groups of antibiotics. Erythromycin is a 14‐membered ring macrolide and foremost member of the class. First‐generation derivatives focused on deficiencies such as compound instability in acidic environments, bitter taste, low water solubility, low oral bioavailability, and gastrointestinal and cardiac side effects. Many of these problems were at least partly solved by first‐generation derivatives such as esters and salts that made the active entities less prone to degradation. Second‐generation derivatives chemically changed substituents on the aglycone to stabilize it from intramolecular decomposition. This group includes clarithromycin and azithromycin that have become the most important macrolides to date. The problem of bacterial resistance to antibiotics was elegantly addressed by the ketolides. Telithromycin (Ketek®) was the first ketolide (third generation of erythromycin derivatives) to be approved and marketed, but postmarketing surveillance uncovered side effects and its use has been restricted. Macrolides are also important veterinary antibiotics and three new agents have been developed. Studies have continued to search for new agents using combinatorial biosynthesis, but the generation of large numbers of novel polyketides remains unfulfilled at this time.
Paint and Finish Removers
Authors: Bardole Jay A. , White David L.
Published: September 2015

Finish removers play an important role in the recycling of durable goods. By removing the old coating and applying a new one, the useful life of items such as furniture, automobiles, aircraft, and buildings can be extended. Finishes are removed from woods, metals, and plastics; however, no single type of remover can be effective in all of the different applications in which removers are used. The properties of removers vary considerably to meet diverse uses and requirements. Important considerations in selecting a product and a process are the safety of the person using the remover and the impact the finish removal process has on the environment.
Size Measurement of Particles
Authors: Trottier Remi
Published: September 2015

The size distribution of particles is of importance to a wide variety of particulate systems in the chemical process industries. The compacting and sintering behavior of metallurgical powders, flow characteristics of granular materials, hiding power of paint pigments, and the combustion efficiency of coal and sprayed liquids all depend on particle size.

Methods of size measurement ranging from traditional sieving through the use of modern instrumentation such as laser diffraction equipment and optical counters are discussed. Data representation and sampling procedures, as well as the factors to be considered when selecting a technology, most importantly the size range, accuracy, detection limits, resolution, costs, and reliability, are also presented.
Silicon Compounds: Anthropogenic Silicas and Silicates
Authors: Falcone James S.
Published: September 2015

Synthetic alkali silicates, M2O·mSiO2·nH2O, where M = Li, Na, and K, are manufactured as liquids or glasses that readily dissolve in water to form alkaline solutions. These silicates contain a complex mixture of polymeric species with different properties and applications including detergency, soil stabilization, water and waste treatment, and as a raw material for the syntheses of silica sols, gels and precipitates, zeolites, and clays. The article discusses the properties of the synthetic alkali silicates that determine their function in a variety of commercial applications. Economic, manufacturing, regulatory, and environmental aspects of silicate production and usage are reviewed.
Perfluorinated Polymers
Authors: Gangal Subhash V. , Brothers Paul D.
Published: September 2015

This article provides information on several perfluorinated polymers; their manufacture, properties, fabrication, and applications are discussed.

Polytetrafluoroethylene (PTFE), known as Teflon PTFE, a perfluorinated straight‐chain high molecular weight polymer, is commercially important because of its chemical inertness, heat resistance, excellent electrical insulation properties, and low friction coefficient. PTFE is used in the chemical processing industry for structures, linings, seals, and hose or tubing.

Perfluorinated ethylene–propylene (FEP), a copolymer of tetrafluoroethylene (TFE) and hexafluoropropylene (HFP), has a melt viscosity low enough for conventional melt processing. The extrusion grade is suitable for tubing, wire coating, and cable jacketing.

Copolymers of ethylene and tetrafluoroethylene (ETFE) and specifically modified ETFE are commercially valuable because of their good tensile strength, moderate stiffness, and outstanding impact strength. The general‐purpose resin is used for insulating and jacketing low voltage power wiring for mass transport system, wiring for chemical plants, and control and instrumentation wiring.

Perfluoroalkoxy (PFA) fluorocarbon resin copolymers contain a fluorocarbon backbone in the main chain and randomly distributed perfluorinated ether side chains. General‐purpose grade applications include tubing, molded parts, and insulation for electrical wire and cables. Some grades of this polymer are suitable in semiconductor manufacturing, fluid handling systems, and instrumentation for precise measurements of fluid systems.

Copolymers of tetrafluoroethylene–perfluorodioxole are perfluorinated amorphous polymers, known as Teflon AF, having high temperature stability, excellent chemical resistance, high transparency, and low refractive index. They are used in antireflective coatings, low dielectric coatings, pellicles in electronic chips, plastic optical fiber, and in gas separation membranes.
Sediment transport‐based metrics of wetland stability
Authors: Ganju Neil K. , Kirwan Matthew L. , Dickhudt Patrick J. , Guntenspergen Glenn R. , Cahoon Donald R. , Kroeger Kevin D.
Published: September 2015

Despite the importance of sediment availability on wetland stability, vulnerability assessments seldom consider spatiotemporal variability of sediment transport. Models predict that the maximum rate of sea level rise a marsh can survive is proportional to suspended sediment concentration (SSC) and accretion. In contrast, we find that SSC and accretion are higher in an unstable marsh than in an adjacent stable marsh, suggesting that these metrics cannot describe wetland vulnerability. Therefore, we propose the flood/ebb SSC differential and organic‐inorganic suspended sediment ratio as better vulnerability metrics. The unstable marsh favors sediment export (18 mg L−1 higher on ebb tides), while the stable marsh imports sediment (12 mg L−1 higher on flood tides). The organic‐inorganic SSC ratio is 84% higher in the unstable marsh, and stable isotopes indicate a source consistent with marsh‐derived material. These simple metrics scale with sediment fluxes, integrate spatiotemporal variability, and indicate sediment sources.