bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Orthopantomography and Computed Tomography Image for Assessing the Relationship between Impacted Mandibular Third Molar and Mandibular Canal
Authors: Shankar Uma , Hari KR , Reddy T Praveen Kumar , Katakam Shravan Kumar , Janga Deepti
Published: January 2013

Background

Permanent mandibular third molar are most commonly impacted teeth. In planning the surgical removal of mandibular third molar, correct diagnosis requires not only their precise spatial location, but also a thorough and accurate assessment of the intimate relationship with adjacent anatomical structures. Various imaging modalities have been used for localizing the mandibular third molar but not satisfactorily.

Aim

This prospective study of 30 patients with 42 impacted mandibular third molars was carried out with the aim of finding evidence for justifying the use of computed tomography and orthopantomography as a diagnostic modality, prior to surgical intervention of impacted mandibular third molar.

Materials and methods

Subjective evaluation of the CT and OPG images by two observed had shown that there was significant difference between the CT and OPG for radiographic visibility of mandibular canal in relation to third molar.

Results

Data analysis was done with Chi-square test (χ2) and z-test to find the significant difference between the two radiographic modalities OPG and CT in localizing special relationship of impacted mandibular third molar. The comparison of OPG and CT showed z-value >1.5 in darkening of roots (1.98), deflection of root (2.00) interruption of z-value = 0 in narrowing of canal and dark, bifid apexes. Also it showed p-value <0.05 in all the radiographic signs except narrowing of mandibular canal and and dark and bifid apexes.

Conclusion

The spiral CT image provides a unique opportunity to determine the exact position of impacted mandibular third molar and their relationship to adjacent structure in all three planes.

Clinical significance

Computed tomography is highly instrumental in depicting the relationship of mandibular third molar with inferior alveolar nerve canal before treatment and accurate appraisal of the several aspects can be made regarding prognosis.

How to cite this article

Katakam SK, Shankar U, Thakur D, Reddy TPK, Hari KR, Janga D. Comparison of Orthopantomography and Computed Tomography Image for Assessing the Relationship between Impacted Mandibular Third Molar and Mandibular Canal. J Contemp Dent Pract 2012;13(6):819-823.
The Influence of Tray Space and Repeat Pours on the Accuracy of Monophasic Polyvinylsiloxane Impression
Authors: Rajapur Anand , Dixit Santosh , Hoshing Chetan , Raikar Sonal
Published: January 2013

Aim

While literature demonstrates that the optimum accuracy is obtained with the custom trays, the use of stock trays for elastomeric impressions appears to be popular in general practice. The aim of the study was to evaluate the effect of thickness of impression material on the dimensional accuracy of impressions made from monophasic polyvinylsiloxane impression material. This study also studies the dimensional stability of the impressions poured at different time intervals.

Materials and methods

A metal model simulating two abutment teeth was fabricated along with reference lines inscribed on them. Custom impression trays were fabricated with spacer thickness of 2, 4 and 6 mm. impressions were made using monophasic polyvinyl siloxane impression material. The impressions were poured and stone models were obtained. The dimensional accuracy of the impressions were determined indirectly by measuring the dimensional changes of the recovered stone models. The dimensional stability was also evaluated by pouring the impressions at time intervals of 1 hour, 24 hours and 7 days. The obtained data was statistically analyzed.

Results

The results of the study indicated that the impressions made from 2 and 4 mm tray space produced more accurate stone models when compared to 6 mm tray space. There was no significant deviation in the mesiodistal and buccolingual dimensions when impressions were made using impression trays with 2, 4 and 6 mm tray spacers. There was a significant decrease in interabutment distance (p = 0.001) and height of the abutment (p = 0.024) when impressions were made using impression trays with a tray space of 6 mm. There were no significant differences found among the stone models obtained from 1 hour, 24 hours and 1 week pour times.

Conclusion

The mesiodistal and buccolingual dimensions of the abutments were not affected by the variations in thickness of impression material. There was a decrease in the height of the abutment which was clinically not significant. As the thickness of the impression material increased, the interabutment space decreased, which is a factor of concern when impressions are made for fixed partial dentures.

Clinical significance

When monophasic polyvinylsiloxane is used as the impression material, stock trays can be used for making impressions for individual castings.

How to cite this article

Rajapur A, Dixit S, Hoshing C, Raikar S. The Influence of Tray Space and Repeat Pours on the Accuracy of Monophasic Polyvinylsiloxane Impression. J Contemp Dent Pract 2012;13(6):824-829.
Evaluation of Apical Sealing Ability of Four Different Sealers using Centrifuging Dye Penetration Method: An in vitro Study
Authors: Joseph Romel
Published: January 2013

Aim

The aim of this in vitro study was to evaluate the apical seal obtained with four root canal sealers AH 26, Sealapex, Endoflas FS and AH Plus, with lateral condensation.

Materials and methods

Sixty root canals were prepared using the step-back technique. The specimens were divided into four experimental groups of 12 teeth and two control groups of 12 teeth. The experimental groups were obturated by laterally condensed gutta-percha with one of the tested sealers and control groups were obturated without any sealer. Methylene blue dye penetration with centrifuging method was used to evaluate the apical sealing ability. The quantitative apical leakage of each specimen was measured after 2 weeks.

Results

The results showed no significant differences between all groups except between AH Plus and Endoflas FS (<0.05). AH Plus showed significantly less leakage than Endoflas FS.

Conclusion

AH Plus showed the least leakage compared to AH 26, Sealapex and Endoflas FS.

How to cite this article

Joseph R, Singh S. Evaluation of Apical Sealing Ability of Four Different Sealers using Centrifuging Dye Penetration Method: An in vitro Study. J Contemp Dent Pract 2012;13(6):830-833.
An in vitro Investigation into the Cytotoxicity of Methyl Methacrylate Monomer
Authors: Sreekumar AV , Pradeep Nishna
Published: January 2013

Aim of this study was to assess the cytotoxicity of monomer. An in vitro study was designed to study the growth inhibitory effect of monomer (Stellon, Denture Material Improved, Type I, Class I, Dental Products of India Limited) on cells seeded in petri dishes and maintained in an incubator with 5% carbon dioxide at 37°C. The growth of V79 cells (fibroblast cells) maintained in a culture medium to which monomer was added was studied for a period of 5 days. Results of this study pointed out that even at a concentration of 1 μl of monomer, the cell growth was significantly inhibited, when compared to the control group. The number of viable cells decreased dramatically whereas dead cells increased in the culture groups treated with the monomer. The cytotoxic effect was dose dependent. As the concentration increased from 1 to μl there was a marked inhibition of cell growth and a corresponding increase in dead cell count. Results of this study proved beyond doubt that monomer is indeed cytotoxic even in very low concentrations. Thus, it becomes imperative to adopt every possible means to minimize residual monomer content in heat cured resins. Also precautions to minimize tissue contact should be taken while handling monomer by the dentist and dental personnel in the laboratory.

How to cite this article

Pradeep N, Sreekumar AV. An in vitro Investigation into the Cytotoxicity of Methyl Methacrylate Monomer. J Contemp Dent Pract 2012;13(6):838-841.
Management of Large Periapical Cystic Lesion by Aspiration and Nonsurgical Endodontic Therapy using Calcium Hydroxide Paste
Authors: Thomas Kunjamma , Prasanth Dhanapal T , Simon Elsy P
Published: January 2013

Aim

To report a case of conservative nonsurgical management of periapical lesions.

Background

Small periapical lesions of endodontic origin usually heal by conventional endodontic therapy alone. Larger periapical lesions presumed to be cystic may require additional treatment protocols to aid in regression. Conservative nonsurgical management of such lesions eliminates the possible complications of surgery and has wider patient compliance and acceptance.

Case description

A periapical cystic lesion associated with maxillary central incisor and lateral incisor was treated conservatively using buccal aspiration decompression followed by conventional endodontic therapy employing calcium hydroxide iodoform paste as intracanal medicament is reported.

Clinical significance

The treatment was successful as evidenced by relief of symptoms and radiographic evaluation.

Conclusion

Large periapical cyst-like lesions can resolve by nonsurgical endodontic therapy employing calcium hydroxide intracanal interappointment medicament.

How to cite this article

Thomas K, Dhanapal PT, Simon EP. Management of Large Periapical Cystic Lesion by Aspiration and Nonsurgical Endodontic Therapy using Calcium Hydroxide Paste. J Contemp Dent Pract 2012;13(6):897-901.
Stratospheric impact on tropospheric ozone variability and trends: 1990–2009
Authors: Hess P. G. , Zbinden R.
Published: January 2013

Abstract. The influence of stratospheric ozone on the interannual variability and trends in tropospheric ozone is evaluated between 30 and 90° N from 1990–2009 using ozone measurements and a global chemical transport model, the Community Atmospheric Model with chemistry (CAM-chem). Long-term measurements from ozonesondes, at 150 and 500 hPa, and the Measurements of OZone and water vapour by in-service Airbus aircraft programme (MOZAIC), at 500 hPa, are analyzed over Japan, Canada, the Eastern US and Northern and Central Europe. The measurements generally emphasize northern latitudes, although the simulation suggests that measurements over the Canadian, Northern and Central European regions are representative of the large-scale interannual ozone variability from 30 to 90° N at 500 hPa. CAM-chem is run with input meteorology from the National Center for Environmental Prediction; a tagging methodology is used to identify the stratospheric contribution to tropospheric ozone concentrations. A variant of the synthetic ozone tracer (synoz) is used to represent stratospheric ozone. Both the model and measurements indicate that on large spatial scales stratospheric interannual ozone variability drives significant tropospheric variability at 500 hPa and the surface. In particular, the simulation and the measurements suggest large stratospheric influence at the surface sites of Mace Head (Ireland) and Jungfraujoch (Switzerland) as well as many 500 hPa measurement locations. Both the measurements and simulation suggest the stratosphere has contributed to tropospheric ozone trends. In many locations between 30–90° N 500 hPa ozone significantly increased from 1990–2000, but has leveled off since (from 2000–2009). The simulated global ozone budget suggests global stratosphere-troposphere exchange increased in 1998–1999 in association with a global ozone anomaly. Discrepancies between the simulated and measured ozone budget include a large underestimation of measured ozone variability and discrepancies in long-term stratospheric ozone trends. This suggests the need for more sophisticated simulations including better representations of stratospheric chemistry and circulation.
Assessment of the Level-3 MODIS daily aerosol optical depth in the context of surface solar radiation and numerical weather modeling
Authors: Ruiz-Arias J. A. , Dudhia J. , Gueymard C. A. , Pozo-Vázquez D.
Published: January 2013

Abstract. The daily Level-3 MODIS aerosol optical depth (AOD) product is a global daily spatial aggregation of the Level-2 MODIS AOD (10-km spatial resolution) into a regular grid with a resolution of 1° × 1°. It offers interesting characteristics for surface solar radiation and numerical weather modeling applications. However, most of the validation efforts so far have focused on Level-2 products and only rarely on Level 3. In this contribution, we compare the Level-3 Collection 5.1 MODIS AOD dataset from the Terra satellite available since 2000 against observed daily AOD values at 550 nm from more than 500 AERONET ground stations around the globe. Overall, the mean error of the dataset is 0.03 (17%, relative to the mean ground-observed AOD), with a root mean square error of 0.14 (73%, relative to the same), but these errors are also found highly dependent on geographical region. We propose new functions for the expected error of the Level-3 AOD, as well as for both its mean error and its standard deviation. Additionally, we investigate the role of pixel count vis-à-vis the reliability of the AOD estimates, and also explore to what extent the spatial aggregation from Level 2 to Level 3 influences the total uncertainty in the Level-3 AOD. Finally, we use a radiative transfer model to investigate how the Level-3 AOD uncertainty propagates into the calculated direct normal and global horizontal irradiances.
The influence of precipitation and temperature input schemes on hydrological simulations of a snow and glacier melt dominated basin in Northwest China
Authors: Ji X. , Luo Y.
Published: January 2013

Abstract. Basins with glaciers and snow provide water storage and supply for downstream irrigated farmland, but their hydrology is often poorly known because there are limited observation networks in high mountain regions. Large uncertainties in hydrological simulations also arise from errors associated with meteorological forcing data. The influence of precipitation and temperature forcing data on hydrological simulations in rain/snow dominated watershed is well documented, but less so in basins with glaciers. We analyzed the impacts and reliability of precipitation/temperature input solutions on hydrological simulations in the glacier/snow dominated Manas River Basin, showing that precipitation pattern has significant impact on snow accumulation and melt, and further impacts on simulated glacier melt behavior. The temperature inputs affect not only the timing of discharge but also the total water yield. The uncertainty associated with simple estimated input data propagates and is amplified through the modeling process. We suggest that the impacts of forcing data on hydrological simulations in basins with glaciers are more complex than in common rain/snow dominated watersheds. Glacier melt behavior may conceal uncertainties that are actually derived from input data. Assessment of hydrological model performance should include investigation of key processes involved in the hydrologic cycle individually, not just comparisons of simulated and observed discharge.
The modification of the typhoon rainfall climatology model in Taiwan
Authors: Lee C.-S. , Huang L.-R. , Chen D. Y.-C.
Published: January 2013

Abstract. This study is focused on the modification of a typhoon rainfall climatological model, by using the dataset up to 2006 and including data collected from rain gauge stations established after the 921 earthquake (1999). Subsequently, the climatology rainfall models for westward- and northward-moving typhoons are established by using the typhoon track classification from the Central Weather Bureau. These models are also evaluated and examined using dependent cases collected between 1989 and 2006 and independent cases collected from 2007 to 2011. For the dependent cases, the average total rainfall at all rain gauge stations forecasted using the climatology rainfall models for westward- (W-TRCM12) and northward-moving (N-TRCM12) typhoons is superior to that obtained using the original climatological model (TRCM06). Model W-TRCM12 significantly improves the precipitation underestimation of model TRCM06. The independent cases show that model W-TRCM12 provides better accumulated rainfall forecasts and distributions than model TRCM06. A climatological model for accompanied northeastern monsoons (A-TRCM12) for special typhoon types has also been established. The current A-TRCM12 model only contains five historical cases and various typhoon combinations can cause precipitation in different regions. Therefore, precipitation is likely to be significantly overestimated and high false alarm ratios are likely to occur in specific regions. For example, model A-TRCM12 significantly overestimates the rainfall forecast for Typhoon Mitag, an independent case from 2007. However, it has a higher probability of detection than model TRCM06. From a disaster prevention perspective, a high probability of detection is much more important than a high false alarm ratio. The modified models can contribute significantly to operational forecast.
Psychological Characteristics of Patients Treated by Chronic Maintenance Hemodialysis
Authors: Pop-Jordanova Nada D. , Polenakovic Momir H.
Published: January 2013

Studies related to psychological aspects of dialysis patients show that depression and anxiety are the most common characteristics.

The aim of our study was to analyze the personality profile in patients on chronic maintenance dialysis and to evaluate more specifically the level of depression. The total number of patients was 68 (30 females and 38 males), with mean age 62.3 and 56.5 for females and males respectively. Mean duration of dialysis was 6.73 years for females and 6.68 years for men (the period varied from 0.5 to 18 years).

For the evaluation of psychological characteristics, we used two psychometric instruments: Minnesota Multiphase Personality Inventory (MMPI- 201) and Beck Depression Inventory. The obtained results confirmed the presence of depression in patients treated with hemodialysis. The level of depression is variable (minimal is present in 21.43%; mild in 35.71%; moderate in 17.85% and severe in 14.28% of patients). The depression is significantly positively correlated with age (p<0.05) as well as with educational level, and negatively with the duration of dialysis.

Specific characteristics of personality obtained with MMPI are hypersensitivity, depressive mood, and withdrawal from friends and relatives. More specific emotional traits are the accentuated anxiety, low level of hostility, but very high passive aggression which destroys their social communications. Some response measures for depression such as relaxation training, psychological support, music therapy, or peripheral biofeedback are recommended.
La Reforma procesal penal de Nicaragua: Acopio de experiencia centroamericana
Authors: Barrientos Pellecer César
Published: January 2013

DOI: http://dx.doi.org/10.5377/derecho.v0i1.731 Revista de Derecho No.1 2001 pp.1-24
Acciones procesales en el Nuevo Código Procesal Penal de Nicaragua
Authors: Tijerino Pacheco José María
Published: January 2013

DOI: http://dx.doi.org/10.5377/derecho.v0i1.733 Revista de Derecho No.1 2001 pp.53-90
El nuevo Código Procesal Penal y su relación con la Ley Orgánica del Ministerio Público
Authors: Bolaños Ortega Maria Lourdes
Published: January 2013

DOI: http://dx.doi.org/10.5377/derecho.v0i1.735 Revista de Derecho No.1 2001 pp.91-100
Ministerio Público y Policía Nacional: Una alianza necesaria
Authors: Sánchez Romero Cecilia , Bautista Lara Francisco Javier
Published: January 2013

DOI: http://dx.doi.org/10.5377/derecho.v0i1.736 Revista de Derecho No.1 2001 pp.101-120
El procedimiento común u ordinario
Authors: Vega Vargas Gustavo A
Published: January 2013

DOI: http://dx.doi.org/10.5377/derecho.v0i1.740 Revista de Derecho No.1 2001 pp.201-236
Principio de inocencia en el Código Procesal de Nicaragua
Authors: Ramírez García Luis Rodolfo
Published: January 2013

DOI: http://dx.doi.org/10.5377/derecho.v0i1.742 Revista de Derecho No.1 2001 pp.253-262
El Juez y el Ministerio Públio en el Nuevo Código Procesal Penal Nicaraguense
Authors: Gonzalez Cano María Isabel
Published: January 2013

DOI: http://dx.doi.org/10.5377/derecho.v0i3.717 Revista de Derecho No.3 2002 pp.57-88
"Elementos del Crimen" así como Reglas de Procedimiento y Prueba de la Corte Penal Internacional
Authors: Ambos Kia
Published: January 2013

DOI: http://dx.doi.org/10.5377/derecho.v0i3.719 Revista de Derecho No.3 2002 pp.133-147
La Quiebra Bancaria en Nicaragua: Algunas consideraciones y posibles reformas a les leyes que regulan
Authors: Icaza Martínez Juan José
Published: January 2013

DOI: http://dx.doi.org/10.5377/derecho.v0i3.724 Revista de Derecho No.3 2002 pp.241-257
Escrito de Alegatos Finales Presentado por el Estado de Nicaragua Dentro del Proceso Promovido en Contra del Estado de Honduras, por la Violación de Diversos Instrumentos Jurídicos de Integración Regional
Authors: Castillo Salazar Edmundo
Published: January 2013

DOI: http://dx.doi.org/10.5377/derecho.v0i3.726 Revista de Derecho No.3 2002 pp.275-304
Escrito de Conclusiones de Honduras
Authors: Castillo Salazar Edmundo
Published: January 2013

DOI: http://dx.doi.org/10.5377/derecho.v0i3.727 Revista de Derecho No.3 2002 pp.305-340
Sentencia de Juicio Nicaragua vs Honduras
Authors: Castillo Salazar Edmundo
Published: January 2013

DOI: http://dx.doi.org/10.5377/derecho.v0i3.728 Revista de Derecho No.3 2002 pp.341-386
Presentación No.3 2002
Authors: Icaza Martínez Juan José
Published: January 2013

DOI: http://dx.doi.org/10.5377/derecho.v0i3.729 Revista de Derecho No.3 2002 pp.i-ii
Enseigner à l’école primaire une géographie problématisée : un défi?
Authors: Philippot Thierry
Published: January 2013

Depuis la fin des années 1980, les didacticiens de la géographie et les textes officiels mettent en avant un enseignement problématisé de la géographie. Pour les enseignants généralistes de l’école primaire française, cette problématisation est-elle aussi évidente que cela à mettre en oeuvre dans leurs pratiques d’enseignement? Après avoir précisé le sens des termes «problème» et «problématisation» dans le champ scolaire, nous présentons ces propositions didactiques adressées aux enseignants. Enfin, nous mobilisons les résultats d’une recherche empirique qui donne à voir une géographie enseignée peu «problématisée», ce qui conduit à penser que la «problématisation» dans l’enseignement de la géographie à l’école primaire ne semble pas aller de soi.
Compréhension en lecture au primaire : actualisation des pratiques enseignantes
Authors: Martel Virginie , Lévesque Jean-Yves , Aubin-Horth Shanoussa
Published: January 2013

Afin de dresser le portrait actuel des pratiques enseignantes en matière de compréhension en lecture aux deuxième et troisième cycles du primaire, la présente recherche a établi les objectifs et les pratiques pédagogiques de 413 enseignantes et enseignants de différentes régions du Québec. Alors que les études réalisées au tournant des années 2000 laissaient penser que les enseignants référaient à des pratiques pédagogiques relativement traditionnelles et peu tournées vers l’enseignement de stratégies, les résultats de cette recherche démontrent que les enseignantes et enseignants déclarent mettre en oeuvre des objectifs et des pratiques pédagogiques liés au rôle de la personne enseignante comme modèle-lecteur et à la nécessité de proposer un contexte d’enseignement et d’apprentissage signifiant, réflexif et stratégique.
Azine Dyes
Authors: Smith Roy E. ,   Updated by Staff
Published: January 2013

Azine, oxazine, and thiazine dyes were among the earliest dyes. The names are derived from the 6‐membered heterocyclic ring present in all dyes of these classes: 1,4‐diazine; 1,4‐oxazine, and 1,4‐thiazine.The parent rings are always included in phenazine, phenoxazine, and phenothiazine. The first of these dyes to be made synthetically was Perkin's mauveine. These dyes were historically more important then they are at present. However, a few are still used today. All of these dyes are vattable, ie, they are reduced to colorless forms, then oxidized back to the dye. They therefore offer good fastness to oxidation. Because of this property, many find use as redox indicators in titrations. Methylene Blue is a classic thiazine dye and is still very popular today. It is used in textile dyeing, basic uses are for dyeing acrylic fibers, leather, and coloring of paper. It is also used as a biologically active photosensitizer and is useful in the diagnosis and treatment of medical conditions. Methylene Blue‐curcumin is used in the treatment of Alzheimer's disease.
Dimethylformamide
Authors: Marsella John A. ,   Updated by Staff
Published: January 2013

Dimethylformamide is a clear, hygroscopic liquid with a slight amine odor. It was first synthesized in 1893 by heating a mixture of sodium formate and dimethylammonium chloride and later prepared by direct reaction of dimethylamine with formic acid. Although it does not occur widely in nature, traces of DMF have been detected in sausages, cooked mushrooms, grapes, and wine. The solvent properties of DMF are particularly attractive. Because of its high dielectric constant, aprotic nature, wide liquid range, and low volatility, it is frequently used for chemical reactions and other applications requiring high dissolving power. DMF is often referred to as the universal solvent. Important uses are in the production and processing of polymers. It is used as a spinning solvent for polyacrylonitrile fiber and polyurethane fiber (Spandex), and production of synthetic leather. It is also used in many processes in the production of pharmaceuticals. DMF is not used in a consumer setting so its toxicity is relatively low.
Dye Carriers
Authors: de Guzman Ernesto , Sutton Boyce ,   Updated by Staff
Published: January 2013

Dye carriers are needed for complete dye penetration of polyester fibers. Carriers cause glass‐transition of the polyester polymer to become lower and allow penetration of water‐insoluble dyes into the fiber. It is difficult for dye solutions in water to penetrate synthetic fibers such as polyester, cellulose triacetate, polyamides, and polyacrylics which are somewhat hydrophobic. Disperse dyes commonly used to dye polyester are nonionic and dye the polyester through a diffusion mechanism. Deep shades and full fastness properties can be achieved with carriers using disperse dyes and carriers. The formulation of a carrier depends on: the carrier‐active chemical compound; the emulsifier; special additives; and environmental concerns. Dyeing procedures vary according to fiber content of the textile material and the equipment to be used. Textile dyeing is the largest industry that uses dye carriers, but dye carriers are found in other dyeing processes such as in hair dyes and dyeing of plastic.
Fracture Mechanics
Authors: Recho Naman
Published: January 2013

Fracture mechanics consist in studying the interaction between a geometric discontinuity (crack) and the surrounding continuum, as well as the evolution of this discontinuity.On one hand fracture mechanics is concerned with the description of mechanical fields in the neighborhood of the tip of the crack and the energies that are associated therewith and on the other hand, it deals with the evaluation of the harmfulness of a crack in terms of its propagation.
Talc
Authors: McCarthy Edward F. ,   Updated by Staff
Published: January 2013

Talc is a naturally occurring mineral that is a crystalline hydrous magnesium silicate belonging to the general mineral family of the layered silicates. Other layered silicates are kaolin, mica, and pyrophyllite. The commercial value of a talc ore is based on its color, purity, accessibility, proximity to the market, and accessory minerals. Of these the most critical is color. Most talc is mined by open‐pit methods, but there are some underground mines. Mining of talc is very sensitive to contamination during the mining process. Information of mining and processing are given.

The FDA has studied talc used in cosmetics for asbestos. Samples were considered safe, but monitoring continues. Talc is used for in a wide variety of applications. In all of these applications, talc is a functional ingredient. Talc is rarely used as a filler since it is expensive. Uses for talc include in ceramics (principal use), paper, roofing, paint, plastics, rubber, cosmetics, agriculture and food.
Climate Change, Freshwater Ecosystems
Authors: Kernan Martin , Battarbee Richard W. , Moss Brian
Published: January 2013

This article considers the interactions between climate change and other drivers of change including hydromorphological modification, acid deposition, contamination by toxic substances using evidence from laboratory experiments, field experiments, and modeling. This article evaluates these processes in relation to extreme events, seasonal changes, in ecosystems, trends over the decades, mitigation strategies, and ecosystem recovery.

Aspects of hydrophysical, hydrochemical, and ecological change can be used as early indicators of climate change in aquatic ecosystems and it addresses implications for the future climate change for freshwater ecosystems management at the catchment scale
Climate Change, Crop Adaptation
Authors: Yadav Shyam S. , Redden Robert J. , Hatifield Jerry L. , Hall Anthony E. , Lotze‐Campen Hermann
Published: January 2013

The publication of the Stern Review on the Economics of Climate Change and the Fourth Assessment Report by the Intergovernmental Panel on Climate Change in 2007 have pushed the scientific and public debate on climate change a decisive step forward. It is now beyond doubt that anthropogenic greenhouse gas emissions are the main cause of the recently observed climate change. The agricultural sector is directly affected by changes in temperature, precipitation, and carbon dioxide concentrations in the atmosphere. If global temperature increases beyond 2°C world food security could be threatened, given a continuous increase in world population to unprecedented levels above 9 billion this century.

This article covers issues related to both crops and climatic conditions. Climate stress on crops and solutions to counteract these stresses are discussed. Some of the solutions reported are the development of drought and temperature resistant species, crossing food crops with their wild relatives and other genetic engineering solutions. Seed banks and their maintenance are also discussed. The development of energy crops is a strategy to produce alternating energy without impacting food security and impact on the environment and is a possibility. the need for research on crop improvement is presented as are some examples of studies made.
Fischer–Tropsch Process
Authors: de Klerk Arno
Published: January 2013

A Fischer–Tropsch process always forms part of a larger indirect liquefaction facility, which consists of three processing steps. The first step is to convert a carbon source, such as coal, natural gas, biomass, or organic waste, into synthesis gas (syngas). Syngas is a mixture of hydrogen and carbon monoxide, and it is the feed material for a Fischer–Tropsch process, which is the second step in the indirect liquefaction process. Fischer–Tropsch synthesis is the catalytic polymerization and hydrogenation of CO, which produces a synthetic crude oil (syncrude). The syncrude is a multiphase mixture of hydrocarbons, oxygenates, and water. The third step is the refining of the syncrude to products that are traditionally produced from conventional crude oil, such as transportation fuels and petrochemicals. The current contribution deals only with the Fischer–Tropsch process; the generation of syngas and the refining of Fischer–Tropsch syncrude are not discussed in any detail. A Fischer–Tropsch process has three main elements: catalyst, reactor, and gas loop. Fischer–Tropsch catalysis is described to explain the relationship among the different catalyst types, operating conditions, and products. A description of the main syncrude types and their compositions is also provided. Fischer–Tropsch technologies are discussed, with an explanation of the relationship between catalyst and reactor, the tradeoffs involved in different catalyst–reactor combinations, as well as guidelines for technology selection. The role of the Fischer–Tropsch gas loop is outlined, with a discussion of the key elements of the gas loop and how they affect the overall performance of a Fischer–Tropsch process.
Solar Energy Harvesting: Power Electronics Interfaces and Control
Authors: Khaligh Alireza , Dusmez Serkan
Published: January 2013

Among renewable energy sources such as biomass, tidal, minihydro, microturbines, and wind, solar energy is one of the most promising sustainable energy resources. Solar energy is converted to electrical energy in photovoltaic (PV) cells through a process called photovoltaic effect. The output voltage polarity of the PV cell is direct current (DC) whose magnitude depends on the connection type of PV cells/modules, while the output current or power mainly varies with solar irradiance. One of the primary tasks in PV systems is to convert the output DC voltage of PV modules to alternate current (AC) to energize general‐purpose AC loads and utility connection. In addition, an interface, which regulates and adjusts the output voltage of the PV, is required because the output voltage of the PV system varies with various factors such as irradiation and temperature. Meanwhile, the power extracted from the PV system must be optimized based on the weather conditions to get the highest efficiency.

A PV system is a combination of several components such as PV panels, energy storage system (ESS), and power conditioning units (PCUs). In PV systems, PCU is composed of power electronic converters along with special controls/algorithms, and it is responsible for various tasks including ESS charging, maximum power point tracking (MPPT), and DC–AC conversion. This article aims to describe a complete PV system architecture and design by following design steps: PV cell/module/array modeling, MPPT algorithms and implementation, design and control of DC/DC power electronic converters responsible for MPPT operation, and DC/AC inverter to supply general‐purpose AC loads. In addition to the provided basic concepts, an example of a complete stand‐alone PV system design including the system sizing has been presented. The designed system has been simulated, and detailed results are provided.
Operation Reliability of Power Systems
Authors: Li Wenyuan
Published: January 2013

This article presents the basic concepts, topics, indices, outage models of system components, noncoherence phenomenon, and three specific issues in probabilistic system operation reliability assessment. Operation reliability of power systems includes adequacy and security evaluations for real‐time operation from a few minutes to half an hour and operation planning from half an hour up to 1 year. There are fundamental differences between reliability assessments for operation and long‐term system planning. The main features in operation reliability assessment are illustrated, and 26 topics in this area are proposed. The indices for system operation reliability can be classified into three categories: the indices of system operation states, limit violations, and system operation risks. The major challenges in system operation reliability assessment include probabilistic simulations of various operational measures, remedial actions, and system dynamics at different timescales, as well as special requirements in input data and computing speed. Fuzzy set theory can be combined with probability methods to deal with both randomness and fuzziness in time‐varying or condition‐dependent data modeling. The operation adequacy assessment for steady states and operation risk assessments for voltage and transient instability are discussed in detail as typical examples. Probabilistic reliability assessment of power system operation is an important task for power system researchers and engineers today and in the future.
Price Forecasting Techniques in Power Systems
Authors: García‐Martos Carolina , Conejo Antonio J.
Published: January 2013

This tutorial paper provides a brief overview of forecasting techniques for hourly electricity price prediction in both the short and the long term, with an emphasis on analytical, nonheuristic procedures. Appropriate background material on time‐series analysis is reviewed first. Short‐term hourly price forecasting (from 12 to 168 hours in advance) is then addressed considering mostly time‐series tools. Illustrative examples based on both European and North American electricity markets are provided to clarify the functioning of the tools described. Unobserved component models are then introduced to address the long‐term forecasting (from 1 week to 1 year in advance) of hourly electricity prices. An illustrative example based on data from a North‐American electricity market is used to clarify the working of an unobserved component model. Appropriate conclusions are finally drawn.
Interdisciplinary Operation of Natural Gas and Electric Power Systems
Authors: Liu Cong , Shahidehpour Mohammad
Published: January 2013

Electric power generation relies increasingly on the natural gas supply system as additional natural gas‐fired power plants are installed in restructured power systems. In this context, the economics and the reliability of electric power and natural gas systems will impact one another. This article addresses the interdependency of electricity and natural gas systems and summarizes approaches for the interdisciplinary operation and the scheduling of the coupled energy systems.

This article starts from an introduction of basic knowledge for the electric power system and the natural gas system. The survey will be given for the research in the past about the interdependency of natural gas and electric power system. This article presents two integrated short‐term scheduling models. The first one is from the viewpoint of the independent system operator (ISO), which proposes a security‐based methodology for the unit commitment solution when considering the natural gas transmission system and contracts. The second integrated model considers a joint operator for the coordinated scheduling of the interdependent power and natural gas systems. The integrated operator uses a Lagrangian relaxation (LR)–based model for the coordinated least‐cost allocation of natural gas resources to individual gas loads and power plants.
Electrical “Wiring” of Enzymes
Authors: Polsky Ronen , Brozik Susan M. , Xiao Xiaoyin , Holland J. Todd
Published: January 2013

Direct communication with the redox active center of many enzymes can be extremely beneficial for many applications ranging from basic research to the construction of sensors and biofuel cells. Unfortunately, most enzymes have evolved such that they naturally protect their active sites, which are shielded within their protein shell, to work more effectively in native environments. Therefore, much activity has taken place to try and artificially connect external electrode transducers to enzyme redox centers in what is termed electrical “wiring” of enzymes. This review gives a general overview of enzyme wiring including background, methods, and applications.
The Impact of Target Base Rate on Training and Transfer of Learning in Airline Luggage Screening: An Examination of Three Base Rate Scenarios
Authors: Madhavan Poornima , Gonzalez Cleotilde , Brown Jeremy R.
Published: January 2013

We examined the extent to which transfer of training is impacted by target probability and physical similarity of training and transfer stimuli. Participants performed a luggage screening task where they trained on three base rates of weapon presence as follows: 100%, 50% and 20%; at transfer, participants detected the same weapons (Study 1) or novel weapons (Studies 2 and 3) at a base rate of 20%. In Study 3, we modified training such that all participants observed the same absolute number of weapons (n = 100) across base rate conditions. In Study 1, different base rates did not significantly impact transfer. In Study 2, 100% base rates helped hit rates at transfer but increased false alarms via liberal shifts in decision criteria and slowed detection times. Study 3 revealed no effect of base rates on transfer hit rates; however, training on 100% base rates still led to liberal responding and inflated false alarms. Copyright © 2013 John Wiley & Sons, Ltd.
Tailored dielectric and mechanical properties of noncovalently functionalized carbon nanotube/poly(styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene) nanocomposites
Authors: Yadav Santosh Kumar , Mahapatra Sibdas Singha , Cho Jae Whan
Published: January 2013

The preparation of high‐dielectric poly(styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene) (SEBS) composites containing functionalized single‐walled carbon nanotubes (f‐SWCNTs) noncovalently appended with dibutyltindilaurate are reported herein. Transmission electron microscopy and X‐ray photoelectron and Raman spectroscopy confirmed the noncovalent functionalization of the SWCNTs. The SEBS‐f‐SWCNT composites exhibited enhanced mechanical properties as well as a stable and high dielectric constant of approximately 1000 at 1 Hz with rather low dielectric loss at 2 wt% filler content. The significantly enhanced dielectric property originates from the noncovalent functionalization of the SWCNTs that ensures good dispersion of the f‐SWCNTs in the polymer matrix. The f‐SWCNTs also acted as a reinforcing filler, thereby enhancing the mechanical properties of the composites. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
User evaluation of automatically generated keywords and toponyms for geo‐referenced images
Authors: Ostermann Frank O. , Tomko Martin , Purves Ross
Published: January 2013

This article presents the results of a user evaluation of automatically generated concept keywords and place names (toponyms) for geo‐referenced images. Automatically annotating images is becoming indispensable for effective information retrieval, since the number of geo‐referenced images available online is growing, yet many images are insufficiently tagged or captioned to be efficiently searchable by standard information retrieval procedures. The Tripod project developed original methods for automatically annotating geo‐referenced images by generating representations of the likely visible footprint of a geo‐referenced image, and using this footprint to query spatial databases and web resources. These queries return raw lists of potential keywords and toponyms, which are subsequently filtered and ranked. This article reports on user experiments designed to evaluate the quality of the generated annotations. The experiments combined quantitative and qualitative approaches: To retrieve a large number of responses, participants rated the annotations in standardized online questionnaires that showed an image and its corresponding keywords. In addition, several focus groups provided rich qualitative information in open discussions. The results of the evaluation show that currently the annotation method performs better on rural images than on urban ones. Further, for each image at least one suitable keyword could be generated. The integration of heterogeneous data sources resulted in some images having a high level of noise in the form of obviously wrong or spurious keywords. The article discusses the evaluation itself and methods to improve the automatic generation of annotations.
Sample size calculation for studies comparing binary outcomes using historical controls
Authors: Zhang Song , Cao Jing , Ahn Chul
Published: January 2013

In historical control trials (HCTs), the experimental therapy is compared with a control therapy that has been evaluated in a previously conducted trial. Makuch and Simon developed a sample size formula where the observations from the HC group were considered not subject to sampling variability. Many researchers have pointed out that the Makuch–Simon sample size formula does not preserve the nominal power and type I error. We develop a sample size calculation approach that properly accounts for the uncertainty in the true response rate of the HC group. We demonstrate that the empirical power and type I error, obtained over the simulated HC data, have extremely skewed distributions. We then derive a closed‐form sample size formula that enables researchers to control percentiles, instead of means, of the power and type I error accounting for the skewness of the distributions. A simulation study demonstrates that this approach preserves the operational characteristics in a more realistic scenario where the true response rate of the HC group is unknown. We also show that the controlling percentiles can be used to describe the joint behavior of the power and type I error. It provides a new perspective on the assessment of HCTs.
Contemporary management and outcomes for infants born with oesophageal atresia
Authors: Burge D M , Shah K , Spark P , Shenker N , Pierce M , Kurinczuk J J , Draper E S , Johnson P R V , Knight M
Published: January 2013

Background

Reports on the management and outcome of rare conditions, such as oesophageal atresia, are frequently limited to case series reporting single-centre experience over many years. The aim of this study was to identify all infants born with oesophageal atresia in the UK and Ireland to describe current clinical practice and outcomes.

Methods

This was a prospective multicentre cohort study of all infants born with oesophageal atresia and/or tracheo-oesophageal fistula in 2008–2009 in the UK and Ireland to record current clinical management and early outcomes.

Results

A total of 151 infants admitted to 28 paediatric surgical units were identified. Some aspects of perioperative management were universal, including oesophageal decompression, operative technique and the use of transanastomotic tubes. However, there were a number of areas where clinical practice varied considerably, including the routine use of perioperative chest drains, postoperative contrast studies and antireflux medication, with each of these being employed in 30–50 per cent of patients. There was a trend towards routine postoperative ventilation.

Conclusion

The prospective methodology used in this study can help identify practices that all surgeons employ and also those that few surgeons use. Areas of clinical equipoise can be recognized and avenues for further research identified.