bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface ozone variability and trends over the South African Highveld from 1990 to 2007
Authors: Balashov Nikolay V. , Thompson Anne M. , Piketh Stuart J. , Langerman Kristy E.
Published: March 2014

Surface ozone is a secondary air pollutant formed from reactions between nitrogen oxides (NOx = NO + NO2) and volatile organic compounds in the presence of sunlight. In this work we examine effects of the climate pattern known as the El Niño–Southern Oscillation (ENSO) and NOx variability on surface ozone from 1990 to 2007 over the South African Highveld, a heavily populated region in South Africa with numerous industrial facilities. Over summer and autumn (December–May) on the Highveld, El Niño, as signified by positive sea surface temperature (SST) anomalies over the central Pacific Ocean, is typically associated with drier and warmer than normal conditions favoring ozone formation. Conversely, La Niña, or negative SST anomalies over the central Pacific Ocean, is typically associated with cloudier and above normal rainfall conditions, hindering ozone production. We use a generalized regression model to identify any linear dependence that the Highveld ozone, measured at five air quality monitoring stations, may have on ENSO and NOx. Our results indicate that four out of the five stations exhibit a statistically significant sensitivity to ENSO at some point over the December–May period where El Niño amplifies ozone formation and La Niña reduces ozone formation. Three out of the five stations reveal statistically significant sensitivity to NOx variability, primarily in winter and spring. Accounting for ENSO and NOx effects throughout the study period of 18 years, two stations exhibit statistically significant negative ozone trends in spring, one station displays a statistically significant positive trend in August, and two stations show no statistically significant change in surface ozone.
Mineral dust aerosol net direct radiative effect during GERBILS field campaign period derived from SEVIRI and GERB
Authors: Ansell C. , Brindley Helen E. , Pradhan Yaswant , Saunders Roger
Published: March 2014

Colocated Spinning Enhanced Visible and Infrared Imager (SEVIRI) retrieved dust optical depths at 0.55 microns, τ055, and Geostationary Earth Radiation Budget (GERB) fluxes at the top of atmosphere are used to provide, for the first time, an observationally based estimate of the cloud‐free net direct radiative effect (DRE) of mineral dust aerosol from geostationary satellite observations, providing new insights into the influence of time of day on the magnitude and sign of the shortwave, longwave, and overall net effect during sunlit hours. Focusing on the Geostationary Earth Radiation Budget Intercomparison of Longwave and Shortwave radiation (GERBILS) campaign over North Africa during June 2007, the presence of mineral dust aerosol reduces the outgoing longwave radiation at all times of day with the peak reduction clearly following the diurnal cycle of surface temperature. The instantaneous shortwave DRE shows strong dependencies on pristine sky albedo and solar zenith angle such that the same dust loading can induce a positive or negative value dependent on time of day. However, the area mean net DRE over the GERBILS period is dominated by the longwave component at all sampled times of day, with mineral dust inducing a reduction in outgoing net flux of the order of 10W m−2. Hence, in the mean sense, Saharan dust is found to warm the Earth‐atmosphere system over northern Africa and the Middle East.
Laboratory simulations of acid‐sulfate weathering under volcanic hydrothermal conditions: Implications for early Mars
Authors: Marcucci Emma C. , Hynek Brian M.
Published: March 2014

We have completed laboratory experiments and thermochemical equilibrium models to investigate secondary mineral formation under conditions akin to volcanic, hydrothermal acid‐sulfate weathering systems. Our research used the basaltic mineralogy at Cerro Negro Volcano, Nicaragua, characterized by plagioclase, pyroxene, olivine, and volcanic glass. These individual minerals and whole‐rock field samples were reacted in the laboratory with 1 molal sulfuric acid at varying temperatures (65, 150, and 200°C), fluid:rock weight ratios (1:1, 4:1, and 10:1), and durations (1–60 days). Thermochemical equilibrium models were developed using Geochemist's Workbench. To understand the reaction products and fluids, we employed scanning electron microscopy/energy dispersive spectroscopy, X‐ray diffraction, and inductively coupled plasma‐atomic emission spectroscopy. The results of our experiments and models yielded major alteration minerals that include anhydrite, natroalunite, minor iron oxide, and amorphous Al‐Si gel. We found that variations in experimental parameters did not drastically change the suite of minerals produced; instead, abundance, size, and crystallographic shape changed. Our results also suggest that it is essential to separate phases formed during experiments from those formed during fluid evaporation to fully understand the reaction processes. Our laboratory reacted and model predicted products are consistent with the mineralogy observed at places on Mars. However, our results indicate that determination of the formation conditions requires microscopic imagery and regional context, as well as a thorough understanding of contributions from both experiment precipitation and fluid evaporation minerals.
Impact heating and coupled core cooling and mantle dynamics on Mars
Authors: Roberts James H. , Arkani‐Hamed Jafar
Published: March 2014

Several giant impact basins of mid‐Noachian age have been identified on Mars, and the global magnetic field appears to have vanished at about the same time. The impacts that formed these basins delivered a large amount of heat to the planetary interior, modified the pattern of mantle convection, and suppressed core cooling, potentially contributing to the cessation of dynamo activity. Here we investigate the thermal evolution of Mars in response to the largest basin‐forming impacts, using a new method of coupling models of mantle convection with parameterized core cooling. We find that heating by a large impact generates a strong hemispheric upwelling in the mantle, which quickly spreads into a warm layer beneath the stagnant lid. The impact heating of the core leads to spherically symmetric stratification of the core; the outermost layers are strongly heated. This acts as a thermal “blanket” that prevents cooling of the interior and shuts down core convection. While the hottest part of the thermal blanket in the outermost core disappears relatively quickly, dynamo activity does not restart for ~100 Myr, and the core does not return to a fully convective state for ~1 Gyr following the impact.
Large‐scale estimation and uncertainty analysis of gross primary production in Tibetan alpine grasslands
Authors: He Honglin , Liu Min , Xiao Xiangming , Ren Xiaoli , Zhang Li , Sun Xiaomin , Yang Yuanhe , Li Yingnian , Zhao Liang , Shi Peili , Du Mingyuan , Ma Yaoming , Ma Mingguo , Zhang Yu , Yu Guirui
Published: March 2014

Gross primary production (GPP) is an important parameter for carbon cycle and climate change research. Previous estimations of GPP on the Tibetan Plateau were usually reported without quantitative uncertainty analyses. This study sought to quantify the uncertainty and its partitioning in GPP estimation across Tibetan alpine grasslands during 2003–2008 with the modified Vegetation Photosynthesis Model (VPM). Monte Carlo analysis was used to provide a quantitative assessment of the uncertainty in model simulations, and Sobol’ variance decomposition method was applied to determine the relative contribution of each source of uncertainty to the total uncertainty. The results showed that the modified VPM successfully reproduced the seasonal dynamics and magnitude of GPP of 10 flux tower sites on the plateau (R2 = 0.77 − 0.95,p < 0.001). The 6 year mean GPP in Tibetan alpine grasslands was estimated at 223.3 Tg C yr−1(312.3 g C m−2 yr−1). The mean annual GPP increased from western to eastern plateau, with the increase of annual temperature and precipitation and the decrease of elevation, while the decrease of GPP from southern to northern plateau was primarily driven by air temperature. Furthermore, the mean relative uncertainty of the annual GPP was 18.30%, with larger uncertainty occurring in regions with lower GPP. Photosynthetic active radiation, enhanced vegetation index, and the maximum light use efficiency (LUE) are the primary sources of uncertainty in GPP estimation, contributing 36.84%, 26.86%, and 21.99%, respectively. This emphasizes the importance of uncertainty in driving variables as well as that of maximum LUE in LUE model simulation.
Contrasting controls on wildland fires in Southern California during periods with and without Santa Ana winds
Authors: Jin Yufang , Randerson James T. , Faivre Nicolas , Capps Scott , Hall Alex , Goulden Michael L.
Published: March 2014

Wildland fires in Southern California can be divided into two categories: fall fires, which are typically driven by strong offshore Santa Ana winds, and summer fires, which occur with comparatively weak onshore winds and hot and dry weather. Both types of fire contribute significantly to annual burned area and economic loss. An improved understanding of the relationship between Southern California's meteorology and fire is needed to improve predictions of how fire will change in the future and to anticipate management needs. We used output from a regional climate model constrained by reanalysis observations to identify Santa Ana events and partition fires into those occurring during periods with and without Santa Ana conditions during 1959–2009. We then developed separate empirical regression models for Santa Ana and non‐Santa Ana fires to quantify the effects of meteorology on fire number and size. These models explained approximately 58% of the seasonal and interannual variation in the number of Santa Ana fires and 36% of the variation in non‐Santa Ana fires. The number of Santa Ana fires increased during years when relative humidity during Santa Ana events and fall precipitation were below average, indicating that fuel moisture is a key controller of ignition. Relative humidity strongly affected Santa Ana fire size. Cumulative precipitation during the previous three winters was significantly correlated with the number of non‐Santa Ana fires, presumably through increased fine fuel density and connectivity between infrastructure and nearby vegetation. Both relative humidity and the preceding wet season precipitation influenced non‐Santa Ana fire size. Regression models driven by meteorology explained 57% of the temporal variation in Santa Ana burned area and 22% of the variation in non‐Santa Ana burned area. The area burned by non‐Santa Ana fires has increased steadily by 1.7% year−1since 1959 (p < 0.006); the occurrence of extremely large Santa Ana fires has increased abruptly since 2003. Our results underscore the need to separately consider the fuel and meteorological controls on Santa Ana and non‐Santa Ana fires when projecting climate change impacts on regional fire.
Probabilistic prediction of cyanobacteria abundance in a Korean reservoir using a Bayesian Poisson model
Authors: Cha YoonKyung , Park Seok Soon , Kim Kyunghyun , Byeon Myeongseop , Stow Craig A.
Published: March 2014

There have been increasing reports of harmful algal blooms (HABs) worldwide. However, the factors that influence cyanobacteria dominance and HAB formation can be site‐specific and idiosyncratic, making prediction challenging. The drivers of cyanobacteria blooms in Lake Paldang, South Korea, the summer climate of which is strongly affected by the East Asian monsoon, may differ from those in well‐studied North American lakes. Using the observational data sampled during the growing season in 2007–2011, a Bayesian hurdle Poisson model was developed to predict cyanobacteria abundance in the lake. The model allowed cyanobacteria absence (zero count) and nonzero cyanobacteria counts to be modeled as functions of different environmental factors. The model predictions demonstrated that the principal factor that determines the success of cyanobacteria was temperature. Combined with high temperature, increased residence time indicated by low outflow rates appeared to increase the probability of cyanobacteria occurrence. A stable water column, represented by low suspended solids, and high temperature were the requirements for high abundance of cyanobacteria. Our model results had management implications; the model can be used to forecast cyanobacteria watch or alert levels probabilistically and develop mitigation strategies of cyanobacteria blooms.
Lyapunov‐based trajectory tracking controller for a fixed‐wing unmanned aerial vehicle in the presence of wind
Authors: Brezoescu A. , Lozano R. , Castillo P.
Published: March 2014

This paper addresses the directional control problem of autonomous air vehicles in order to obtain trajectory tracking capabilities when flying in other than calm conditions. The control strategy is designed in the framework of the Lyapunov theory, and adaptive techniques are employed for online wind identification. An application of light fixed‐wing unmanned aerial vehicles that consists in tracking straight‐line paths between geo‐referenced waypoints is first formulated, and the dynamic of the cross track error with respect to such trajectory is further obtained from the lateral airplane equations of motion. The dynamic order of the closed‐loop adaptive system is guaranteed to be minimal by choosing the proper variables so that the tuning functions method could be applied. Several simulations taking into account unknown wind have been performed to analyze the behavior and the robustness of the control scheme. Copyright © 2014 John Wiley & Sons, Ltd.
A Smart Nanoassembly for Multistage Targeted Drug Delivery and Magnetic Resonance Imaging
Authors: Li Zhenhua , Dong Kai , Huang Sa , Ju Enguo , Liu Zhen , Yin Meili , Ren Jinsong , Qu Xiaogang
Published: March 2014

Efficient delivery of DNA‐toxin anticancer drugs into nucleus of targeted tumor cells while simultaneously minimizing the side effects to normal tissue is a major challenge for cancer therapy. Herein, a multistage continuous targeting strategy based on magnetic mesoporous silica nanoparticles to overcome the challenge is demonstrated. At the initial‐stage, the magnetic nanoparticle is capable of efficiently accumulating in tumor tissue guided by magnet. Following by the magnetic targeting, the targeting ligand gets it right into the cancer cell by receptor‐mediated endocytosis. Accompanied by endocytosis into the lysosomes, the nanoparticle reverses its surface charge from negative to positive which leads to the separation of charge‐conversional polymer from the nanoparticle to re‐expose the nuclear‐targeting TAT peptide. Finally, TAT peptide facilitates the carriers to enter nucleus and the DNA‐toxin camptothecin can inhibit topoisomerase I to induce cell apoptosis. Furthermore, the nano‐drug delivery system can be simultaneously used as predominant contrast agents for magnetic resonance imaging. This proof of concept might open the door to a new generation of carrier materials in the fields of targeted drug transport platform for cancer theranostics.
Healable, Stable and Stiff Hydrogels: Combining Conflicting Properties Using Dynamic and Selective Three‐Component Recognition with Reinforcing Cellulose Nanorods
Authors: McKee Jason R. , Appel Eric A. , Seitsonen Jani , Kontturi Eero , Scherman Oren A. , Ikkala Olli
Published: March 2014

Nanocomposite hydrogels are prepared combining polymer brush‐modified ‘hard’ cellulose nanocrystals (CNC) and ‘soft’ polymeric domains, and bound together by cucurbit[8]uril (CB[8]) supramolecular crosslinks, which allow dynamic host–guest interactions as well as selective and simultaneous binding of two guests, i.e., methyl viologen (the first guest) and naphthyl units (the second guest). CNCs are mechanically strong colloidal rods with nanometer‐scale lateral dimensions, which are functionalized by surface‐initiated atom transfer radical polymerization to yield a dense set of methacrylate polymer brushes bearing naphthyl units. They can then be non‐covalently cross‐linked through simple addition of poly(vinyl alcohol) polymers containing pendant viologen units as well as CB[8]s in aqueous media. The resulting supramolecular nanocomposite hydrogels combine three important criteria: high storage modulus (G′ > 10 kPa), rapid sol–gel transition (<6 s), and rapid self‐healing even upon aging for several months, as driven by balanced colloidal reinforcement as well as the selectivity and dynamics of the CB[8] three‐component supramolecular interactions. Such a new combination of properties for stiff and self‐healing hydrogel materials suggests new approaches for advanced dynamic materials from renewable sources.
Arrayed rGOSH/PMASH Microcapsule Platform Integrating Surface Topography, Chemical Cues, and Electrical Stimulation for Three‐Dimensional Neuron‐Like Cell Growth and Neurite Sprouting
Authors: Liu Heng‐Wen , Huang Wei‐Chen , Chiang Chih‐Sheng , Hu Shang‐Hsiu , Liao Chia‐Hsin , Chen You‐Yin , Chen San‐Yuan
Published: March 2014

The biocompatible thiol‐functionalized rGOSH/PMASH microcapsules encapsulating nerve growth factor (NGF) are arrayed onto a transparent and conductive substrate, i.e., indium tin oxide (ITO), to integrate electrically stimulated cellular differentiation, electrically controlled NGF release, and topographically rough nano‐surfaces into a 3‐D platform for nerve regeneration. The rGOSH/PMASH microcapsules with microscale topography function not only as an adhesive coating to promote the adhesion of PC12 cells but also as electroactive NGF‐releasing electrodes that stimulate NGF release and accelerate the differentiation of PC12 cells during electrical stimulation. Once electrical treatment is applied, NGF release and electrically enhanced cellular differentiation lead to an obvious increase both in the percentage of cells with neurites and in the neurite length. This length can reach nearly 90 μm within 2 days of cell culture. The average neurite length is significantly increased (four‐fold) after culture on the rGOSH/PMASH microcapsule substrate for 2 days compared with culture on a substrate without an rGOSH/PMASH coating. These multifunctional rGOSH/PMASH microcapsules may be used as potential 3‐D patterned substrates for neural regeneration and neural prosthetics in tissue engineering applications.
Effects of GDNF‐Loaded Injectable Gelatin‐Based Hydrogels on Endogenous Neural Progenitor Cell Migration
Authors: Fon Deniece , Al‐Abboodi Aswan , Chan Peggy P. Y. , Zhou Kun , Crack Peter , Finkelstein David I. , Forsythe John S.
Published: March 2014

Brain repair following disease and injury is very limited due to difficulties in recruiting and mobilizing stem cells towards the lesion. More importantly, there is a lack of structural and trophic support to maintain viability of the limited stem/progenitor cells present. This study investigates the effectiveness of an injectable gelatin‐based hydrogel in attracting neural progenitor cells (NPCs) from the subventricular zone (SVZ) towards the implant. Glial cell‐line‐derived neurotrophic factor (GDNF) encapsulated within the hydrogel and porosity within the hydrogel prevents glial scar formation. By directly targeting the hydrogel implant towards the SVZ, neuroblasts can actively migrate towards and along the implant tract. Significantly more doublecortin (DCX)‐positive neuroblasts surround implants at 7 d post‐implantation (dpi) compared with lesion alone controls, an effect that is enhanced when GDNF is incorporated into the hydrogels. Neuroblasts are not observed at the implant boundary at 21 dpi, indicating that neuroblast migration has halted, and neuroblasts have either matured or have not survived. The development of an injectable gelatin‐based hydrogel has significant implications for the treatment of some neurodegenerative diseases and brain injuries. The ability of GDNF and porosity to effectively prevent glial scar formation will allow better integration and interaction between the implant and surrounding neural tissue.
25th Anniversary Article: Carbon Nanotube‐ and Graphene‐Based Transparent Conductive Films for Optoelectronic Devices
Authors: Du Jinhong , Pei Songfeng , Ma Laipeng , Cheng Hui‐Ming
Published: March 2014

Carbon nanotube (CNT)‐ and graphene (G)‐based transparent conductive films (TCFs) are two promising alternatives for commonly‐used indium tin oxide‐based TCFs for future flexible optoelectronic devices. This review comprehensively summarizes recent progress in the fabrication, properties, modification, patterning, and integration of CNT‐ and G‐TCFs into optoelectronic devices. Their potential applications and challenges in optoelectronic devices, such as organic photovoltaic cells, organic light emitting diodes and touch panels, are discussed in detail. More importantly, their key characteristics and advantages for use in these devices are compared. Despite many challenges, CNT‐ and G‐TCFs have demonstrated great potential in various optoelectronic devices and have already been used for some products like touch panels of smartphones. This illustrates the significant opportunities for the industrial use of CNTs and graphene, and hence pushes nanoscience and nanotechnology one step towards practical applications.
Correlates of urban children's leisure‐time physical activity and sedentary behaviors during school days
Authors: Marques Adilson , Sallis James F. , Martins João , Diniz José , Carreiro Da Costa Francisco
Published: March 2014

Objectives

Understanding correlates of physical activity and sedentary behaviors may contribute to fostering active lifestyles. This study aimed to identify correlates of physical activity and sedentary behaviors in leisure‐time among Portuguese urban children, during school days.

Methods

A cross‐sectional survey was conducted with 802 students (416 boys), aged 10–12 years. A questionnaire was used to collect data of physical activity, sedentary behaviors, psychological and behavioral variables related to physical activity and sedentary behaviors. Analyses were run separately for boys and girls.

Results

Television viewing occupied the most leisure‐time of boys and girls, followed by computer usage, and video game playing. These behaviors occupied 259.7 min/day for boys and 208.6 for girls (P = 0.002). Reported moderate‐to‐vigorous physical activity was 23.7 min for boys and 12.8 min for girls (P < 0.001). Perception of competence and academic achievement were related to physical activity for the boys and girls. Computer use and playing video games with friends were only related to physical activity for the boys. On the other hand, parents' physical activity participation was related with boys' and girls' physical activity. The correlates of sedentary behavior were outdoor play for the boys, age for the girls, and playing video games with friends for both.

Conclusions

This finding suggests that interventions should be considered to replace joint video game time with joint physical activity time. Am. J. Hum. Biol. 26:407–412, 2014. © 2014 Wiley Periodicals, Inc.
Reinforcing biopolymer hydrogels with ionic‐covalent entanglement hydrogel microspheres
Authors: Kirchmajer Damian Martin , Panhuis Marc in het
Published: March 2014

Microscopic hydrogel spheres can be used to improve the mechanical properties of conventional hydrogels. We prepared ionic‐covalent entanglement (ICE) hydrogel microspheres of calcium cross‐linked gellan gum and genipin cross‐linked gelatin using a water‐in‐oil emulsion‐based processing technique. The method was optimized to produce microspheres with number average diameter 4 ± 1 µm. These ICE microspheres were used to reinforce gelatin hydrogels and improve their compressive mechanical properties. The strongest microsphere reinforced hydrogels possessed a compressive mechanical stress at failure of 0.50 ± 0.1 MPa and a compressive secant modulus of 0.18 ± 0.02 MPa. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40557.
A different extensional viscosity prediction based on entry pressure drop
Authors: Yang Jia , Dai Yahui , Li Jigong
Published: March 2014

Extensional viscosity, an important processing parameter, can control the processing properties of polymeric products in industrial processes, such as fiber spinning, blow molding, and film casting. In this article, based on the equivalent thought, the contraction flow in the circular channel was studied without using the power laws, and the new equations of the extensional strain rate and the extensional viscosity based on entry pressure drop were proposed. The extensional viscosity of two high‐density polyethylene melts was predicted using the proposed equations, the Cogswell's equations, the Binding's equations, and the Gibson's equations. Moreover, this prediction was compared with the experimental data of the extensional viscosity. It was found that the predicted extensional viscosity of the proposed equations was close to the experimental data. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40563.
Effect of reaction conditions on grafting ratio and properties of starch nanocrystals‐g‐polystyrene
Authors: Wang Cai , Pan Zelin , Wu Meiyan , Zhao Ping
Published: March 2014

Starch nanocrystals‐g‐polystyrene (StN‐g‐PS) was synthesized by free radical emulsion copolymerization of starch nanocrystals with styrene. The effect of polymerization conditions on grafting efficiency (GE) and grafting ratio (GR) were investigated. It was found that during graft copolymerization procedure both GE and GR increase with increasing monomer concentration and reaction time. As a result the high GE and high GR can be achieved. The good linear fit of the GR with ASt/AOH (the absorption strength ratio of aromatic ring peaks and hydroxyl group peaks) confirmed that during graft copolymerization, FTIR spectra can be used as a simple method for determining GR. X‐ray diffraction showed that the crystallinity of StN‐g‐PS decreased slightly with increasing GR. Grafted polystyrene side chains can improve the interface compatibility of starch nanocrystals with the hydrophobic polymer matrix. The mechanical properties of StN‐g‐PS/rubber nanocomposites can be obviously enhanced. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40571.
Influence of microcapsule shell material on the mechanical behavior of epoxy composites for self‐healing applications
Authors: Tripathi Manorama , Rahamtullah  , Kumar D. , Rajagopal Chitra , Kumar Roy Prasun
Published: March 2014

In this article, we have studied the effect of microcapsule shell material on the mechanical behavior of self‐healing epoxy composites. Liquid epoxy healant was encapsulated in melamine‐formaldehyde (MF) and urea‐formaldehyde (UF), using emulsion polymerization technique to prepare microcapsules of different shell walls. The core content of the microcapsules, as determined by solvent extraction technique was found to be 65 ± 4%, irrespective of the shell wall of microcapsule. Morphological investigations reveal a rough texture of the spherical microcapsules, which was attributed to the presence of protruding polymer nanoparticles on the surface. Epoxy composites containing UF and MF microcapsules (3–15% w/w) were prepared by room temperature curing and their mechanical behaviour was studied under both quasi‐static and dynamic loadings. The tensile strength, modulus, and impact resistance of the matrix was found to decrease with increasing amount of microcapsule in the formulation, irrespective of the shell wall material used for encapsulation. Interestingly, substantial improvement in the fracture toughness of the base resin was observed. Morphological investigations on the cracked surface revealed features like crack pinning, crack bowing, microcracking and crack path deflection, which were used to explain the toughened nature of microcapsule containing epoxy composites. Our studies clearly indicate that the microcapsule shell wall material does not play any significant role in defining the mechanical properties of the composites. In addition, presence of secondary amine functionalities in UF and MF shell wall do not interfere with the reaction of epoxy with triethylene tetramine hardener during the curing process. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40572.
Associations between formative practice quizzes and summative examination outcomes in a medical anatomy course
Authors: McNulty John A. , Espiritu Baltazar R. , Hoyt Amy E. , Ensminger David C. , Chandrasekhar Arcot J.
Published: March 2014

Formative practice quizzes have become common resources for self‐evaluation and focused reviews of course content in the medical curriculum. We conducted two separate studies to (1) compare the effects of a single or multiple voluntary practice quizzes on subsequent summative examinations and (2) examine when students are most likely to use practice quizzes relative to the summative examinations. In the first study, providing a single on‐line practice quiz followed by instructor feedback had no effect on examination average grades compared to the previous year or student performances on similar questions. However, there were significant correlations between student performance on each practice quiz and each summative examination (r = 0.42 and r = 0.24). When students were provided multiple practice quizzes with feedback (second study), there were weak correlations between the frequency of use and performance on each summative examination (r = 0.17 and r = 0.07). The frequency with which students accessed the practice quizzes was greatest the day before each examination. In both studies, there was a decline in the level of student utilization of practice quizzes over time. We conclude that practice quizzes provide some predictive value for performances on summative examinations. Second, making practice quizzes available for longer periods prior to summative examinations does not promote the use of the quizzes as a study strategy because students appear to use them mostly to assess knowledge one to two days prior to examinations. Anat Sci Educ 8: 37–44. © 2014 American Association of Anatomists.
Determining the Viable Unbounded Polyhedron Under Linear Control Systems
Authors: Chen Zheng , Gao Yan
Published: March 2014

This paper proposes a new method to determine the viability of linear differential inclusions on an unbounded polyhedron. Based on nonsmooth analysis and viability theory, a sufficient and necessary condition of viability for a convex cone is presented. We then apply the result to an autonomous continuous‐time positive linear system and a continuous‐time positive linear system with scalar inputs, respectively. We give a sufficient condition that guarantees the viability of linear differential inclusions on an unbounded polyhedron. The advantage of the proposed methods is that determining the viability is transformed into solving a finite number of linear programmings. Finally, the effectiveness of our approach is demonstrated through an example.
A Cognitive Perspective on the Business Case for Corporate Sustainability
Authors: Hockerts Kai
Published: March 2014

This paper proposes that a cognitive perspective on corporate sustainability and competitiveness might allow new insights into the question of the business case. The paper explores how respondents from 12 firms make sense of their firm's investments in corporate sustainability activities by analyzing the mental models evoked. The interviews showed that a business case perspective emerged as the dominant logic. A subsequent analysis of the content of the knowledge schemas that were elicited surfaced four dimensions of corporate sustainability induced competitive advantages: risk reduction, efficiency gains, brand building and new market creation. An analysis of the structure of these knowledge schemas revealed that respondents from firms with lower perceived sustainability performance drew on less differentiated and less integrated cognitive frameworks (focusing on risk and efficiency). Respondents from firms with higher perceived performance drew on more complex mental models to represent the links between corporate sustainability and competitiveness. Copyright © 2014 John Wiley & Sons, Ltd and ERP Environment
British Children Can Be Trafficked Too: Towards an Inclusive Definition of Internal Child Sex Trafficking
Authors: Brayley Helen , Cockbain Ella
Published: March 2014

In research, policy and practice, internal trafficking has been long overshadowed by its international counterpart. Despite the introduction of specific legislation against internal sex trafficking, confusion remains in Britain around how this crime is distinguished from other forms of sexual exploitation. In particular, there have been growing tensions around whether British children can be victims. The need for clarity and consistency has been highlighted by a series of high‐profile cases involving British minors being moved within the UK for sexual exploitation. This article brings ongoing definitional debate into the academic arena, exploring the contents and validity of common arguments against accepting Britons as valid victims. It engages with academic studies, government and third‐sector reports, parliamentary debate and legal statute. Additionally, it features arguments raised by practitioners and policy‐makers at conferences, training and meetings. It proposes an inclusive and more clearly delineated definition of internal child sex trafficking. The acceptance and application of a standardised definition would facilitate more effective, transparent and consistent multi‐agency interventions and data collection. The article will be of interest to practitioners, policy‐makers and academics. It focuses on the UK but contributes to wider international discourse around internal trafficking.

‘There have been growing tensions around whether British children can be victims’

Key Practitioner Messages:

Internal trafficking must be better understood and more clearly defined.

In the UK, confusion has focused on whether Britons can be internally sex trafficked.

Both internal sex trafficking law and associated legislative intent readily accommodate British victims.

There are practical and theoretical flaws in the most common arguments against labelling Britons as trafficked.

A new inclusive definition of internal child sex trafficking is proposed: its application could support more cohesive, consistent and transparent policy, practice and data monitoring.

‘Both internal sex trafficking law and associated legislative intent readily accommodate British victims.’
Utility of Child Report: Correspondence with Parent‐Reported Child Abuse Risk
Authors: Tucker Meagan C. , Rodriguez Christina M.
Published: March 2014

Key Practitioner Messages:

Use multiple informants.

Children can provide useful information.

Comprehensive abuse risk assessment.
Co‐creation and ambiguous ownership within virtual communities: the case of the Machinima community
Authors: Harwood Tracy , Garry Tony
Published: March 2014

This research contributes to a gap in our understanding of value and its cocreation by empirically investigating issues related to ambiguities of legal ownership of cocreated outputs from a virtual experience environment and the subsequent consequences of these on value creation. The context is Machinima, the making of original content using the content of computer games engines wherein a games developer and members of a virtual community simultaneously collaborate to generate and distribute content thus potentially creating tension around ownership and authorship. The investigation had three aims. The first objective was to provide a holistic gestalt of how value is cocreated, transformed, transferred and consumed when the roles of consumer and producer become ‘blurred’. The second objective was to examine how legal ‘ambiguity’ of ownership potentially acts as an enabler of creativity within such contexts. The final objective was to develop a better understanding of the social, economic and legal determinants and consequences of such ambiguity on ownership as both an experience and an implicit legal arrangement. Taken holistically, the findings suggest the ambiguous nature of ownership from a legal perspective contributes and informs creative endeavour from both an organisational and community perspective. Within the context of this investigation, ownership ambiguity paradoxically may provide an on‐going environment in which value creation processes beneficial to both participant and developer flourish. Copyright © 2014 John Wiley & Sons, Ltd.
A Brunswik lens model of consumer health judgments of packaged foods
Authors: Orquin Jacob L.
Published: March 2014

Consumer health judgments of packaged food were compared with an objective healthfulness criterion using a Brunswik lens model. Consumer judgments were obtained from a representative consumer sample (N = 1329) who evaluated the healthfulness of 198 packaged food products. The objective healthfulness criterion was calculated for each product according to its specific nutrition values using a validated nutrition profile. The lens model included explicit cues such as nutrition values, nutrition and health claims, food category, and brand and implicit cues such a packaging design and category representativeness. The study revealed that the objective healthfulness criterion is highly predictable on the basis of cues such as the food category, brand, carbohydrate content, and whether the food is a typical “light” product. However, consumer judgments of food healthfulness are based almost entirely on the food category and to a lesser extent on the brand and consumer familiarity with the product. The results are in conflict with consumers' self‐reported use of nutrition information but are in accordance with findings from studies using implicit methods. Copyright © 2014 John Wiley & Sons, Ltd.
A multilevel perspective on the relationship between interpersonal justice and negative feedback‐seeking behaviour
Authors: Chuang Aichia , Lee Chun‐Yang , Shen Chi‐Tai
Published: March 2014

Drawing on social information processing theory, this study uses a multilevel design to integrate the literature on organizational justice with the literature on feedback‐seeking behaviour. Results from a laboratory study with data involving 690 employees showed that individual‐level interpersonal justice was related to employee negative feedback‐seeking behaviour (NFSB) via the mediation of trust in the supervisor. Multilevel analysis of the follow‐up field study with data involving 390 employees from 46 teams confirmed the findings of the laboratory study and indicated that team‐level interpersonal justice was associated with NFSB through a supportive climate. Also, team‐level supervisor support climate was positively related to individual‐level trust in the supervisor. The paper discusses managerial implications of these findings and suggests directions for future research. Copyright © 2014 ASAC. Published by John Wiley & Sons, Ltd.
Improving colorectal cancer screening in Asian Americans: Results of a randomized intervention study
Authors: Carney Patricia A. , Lee‐Lin Frances , Mongoue‐Tchokote Solange , Mori Motomi , Leung Holden , Lau Christine , Le T. Domi , Lieberman David A.
Published: March 2014

BACKGROUND

The objective of this study was to use a randomized controlled trial design to test the impact of an educational intervention delivered by specially trained community health workers among Chinese, Korean, and Vietnamese participants ages 50 to 75 years on knowledge, attitudes, beliefs, and intentions regarding colorectal cancer screening.

METHODS

Baseline data were collected on participants' demographic characteristics, knowledge, attitudes, beliefs about cancer, its risk factors, and intention to keep up to date on cancer screening in the future. Fifteen intervention sessions were held between April and June of 2011. Follow‐up surveys were administered in the postintervention period to both intervention and control participants. Those randomized to the control group received educational pamphlets in their native language.

RESULTS

The intervention had the greatest influence on the Chinese subgroup, which had improved scores relative to the control group for perceived behavior control and intentions (preintervention vs postintervention change: control group, −0.16; intervention group, 0.11; P = .004), behavioral beliefs on cancer screening (preintervention vs postintervention change: control group, −0.06; intervention group, 0.24; P = .0001), and attitudes toward behavior (preintervention vs postintervention change: control group, −0.24; intervention group, 0.35; P ≤ .0001). The intervention had no effect on behavioral beliefs about cancer, control beliefs, or perceived behavioral control (reliance on family). Although the intention to stay up to date for cancer screening increased in 2 study groups (Chinese and Vietnamese), these increases were not significant.

CONCLUSIONS

An educational program delivered by culturally specific community health educators using culturally appropriate language influences some knowledge, attitude, and behavioral beliefs but not others. Cancer 2014;120:1702–1712. © 2014 American Cancer Society.
Cultural differences and collective action: A social network perspective
Authors: Hu Hai‐Hua , Lin Jun , Cui Wentian
Published: March 2014

This study investigates how cultural differences on the individualism–collectivism (I–C) dimension of social networks influence the outcomes of collective action. Evidence shows that I–C values are indicators of how people construct their social networks and use strong/weak ties as a behavioral reference. Specifically, when compared with individualists, collectivists tend to hold larger strong‐tie networks and endow strong ties with greater interpersonal influence. Results obtained from agent‐based modeling indicate that individualistic cultures are more effective at propagating collective action when one of the two following conditions is met: (1) people have a strong motivation to participate and (2) the connectivity of the social system is low. In contrast, spread of collective action in collectivistic cultures is more effective when motivation is not strong and the connectivity of the social system is high. These findings call for a serious consideration of the role of culture in collective action. © 2014 Wiley Periodicals, Inc. Complexity 20: 68–77, 2015
A comparative study between conventional and liquid‐based cytology in screening for anal intraepithelial lesions in HIV‐positive patients
Authors: Maia Livia Bravo , Marinho Larissa Cardoso , Wanderley Paes Barbosa Tania , Batalha Filho Eronides Salustiano , Ribeiro Velasco Lara Franciele , Garcia Costa Patrícia Godoy , Carneiro Fabiana Pirani , de Oliveira Paulo Gonçalves
Published: March 2014

Anal intraepithelial neoplasia (AIN) is associated with HPV infection and can be detected by cytological screening. While conventional exfoliative cytology (CC) is a low‐cost and nonaggressive method, liquid‐based cytology (LBC) tends to give clearer readings. Although studies of the efficacy of anal cancer screening methods would be of great importance for groups at high risk for AIN, few such studies have been conducted. The aim of the present study was to assess the concordance of CC and LBC in diagnosing anal pre‐neoplastic lesions, and to compare cytological results with anoscopy, histopathological, and molecular biology findings. Comparative study involving 33 HIV‐positive patients, who underwent anoscopy and biopsy of suspected lesions. Concordance between the two cytology methods was calculated, as were the associations between cytology results and findings from other screening methods. A total of 54.5% of cases were considered AIN‐negative by CC and LBC, and concordance between the two methods was statistically significant (P < 0.05). Anoscopy was negative in 15 of the 18 CC‐ and LBC‐negative cases. CC identified 75% of patients with positive biopsy, while LBC identified 85.71% of these patients. Molecular biology results showed that patients with LSIL tested positive for the highest number of HPV subtypes. The associations between positive biopsy and high grade HPV, HPV 16, and multiple HPV infections were not statistically significant. Conventional and liquid‐based cytology are equally effective in screening for anal preneoplastic lesions. Diagn. Cytopathol. 2014;42:840–845. © 2014 Wiley Periodicals, Inc.
Intermediate filament: Structure, function, and applications in cytology
Authors: Dey Pranab , Togra Jyoti , Mitra Suvradeep
Published: March 2014

Intermediate filament (IF) constitutes an important cytoskeletal component in nearly all the vertebrate cells. IFs are present both in the cytoplasm and in the nucleus. They play an important role in providing mechanical strength of the cell and tissue, growth and regeneration, cell survival and apoptosis, and finally cell migration. IFs are also expressed differentially in different body tissues. Therefore, judicious use of IF may provide the diagnosis and confirmation of different malignancies. This is particularly helpful in the diagnosis of metastatic malignant tumor from an unknown primary. Expression of IFs particularly cytokeratin and vimentin is also related to prognosis of tumors. In this review, we have discussed the basic structure, dynamics, distribution of IF in cells, and its role in diagnosis of cytology. Possible prognostic roles of IF are also discussed. Diagn. Cytopathol. 2014;42:628–635. © 2014 Wiley Periodicals, Inc.
Diaphragm dysfunction in heart failure is accompanied by increases in neutral sphingomyelinase activity and ceramide content
Authors: Empinado Hyacinth M. , Deevska Gergana M. , Nikolova‐Karakashian Mariana , Yoo Jeung‐Ki , Christou Demetra D. , Ferreira Leonardo F.
Published: March 2014

Aims

Chronic heart failure (CHF) causes inspiratory (diaphragm) muscle weakness and fatigue that contributes to dyspnoea and limited physical capacity in patients. However, the mechanisms that lead to diaphragm dysfunction in CHF remain poorly understood. Cytokines and angiotensin II are elevated in CHF and stimulate the activity of the enzyme sphingomyelinase (SMase) and accumulation of its reaction product ceramide. In the diaphragm, SMase or ceramide exposure in vitro causes weakness and fatigue. Thus, elevated SMase activity and ceramide content have been proposed as mediators of diaphragm dysfunction in CHF. In the present study, we tested the hypotheses that diaphragm dysfunction was accompanied by increases in diaphragm SMase activity and ceramide content.

Methods and results

Myocardial infarction was used to induce CHF in rats. We measured diaphragm isometric force, SMase activity by high‐performance liquid chromatography, and ceramide subspecies and total ceramide using mass spectrometry. Diaphragm force was depressed and fatigue accelerated by CHF. Diaphragm neutral SMase activity was increased by 20% in CHF, while acid SMase activity was unchanged. We also found that CHF increased the content of C18–, C20–, and C24‐ceramide subspecies and total ceramide. Downstream of ceramide degradation, diaphragm sphingosine was unchanged, and sphingosine‐1‐phosphate level was increased in CHF.

Conclusion

Our major novel finding was that diaphragm dysfunction in CHF rats was accompanied by higher diaphragm neutral SMase activity, which is expected to cause the observed increase in diaphragm ceramide content.