bluuebunny/crossref_metadata_2025 huggingface dataset:
Are students who have been educated in an outcomes-based approach prepared for university mathematics?
Authors: Engelbrecht Johann , Harding Ansie , Phiri Patrick
Published: August 2012

Following the political changes of 1994 in South Africa, the decision was taken to replace the traditional skills-based education system at primary and secondary school level (Grades 1 - 12) with an outcomes-based education system (OBE). The OBE approach, referred to as Curriculum 2005, was introduced into schools in 1998. The implementation of the OBE system did not occur without problems, giving rise to revised initiatives and a fair amount of criticism. The 2009 intake of students at universities is the ﬁrst group of students that had been subjected to the OBE approach for their entire school career. This is also the ﬁrst group of students for whom some form of mathematics was compulsory up to Grade 12 level in the form of mathematics or mathematical literacy. These students were characterised by the fact that their mathematics marks for Grade 12 were exceptionally high and that many more students qualiﬁed for university entrance. This article reports on the impact of this new education system on the mathematics prepared-ness of students entering university. The study involves an empirical analysis of the students in the ﬁrst-year mathematics course for engineering students at the University of Pretoria as well as an analysis of a questionnaire completed by experienced lecturers at this university. The question addressed in this article is how the 2009 intake of students cope with mathematics at university level with regard to Performance General attributes Mathematical attributes Content-related attributesResults indicate a decrease in mathematics performance of these students at university level and that the inﬂated matric marks result in unjustiﬁed expectations. However, it is not unusual for marks to decrease from school to university and there is still too little evidence for serious concern. The study also indicates that these students seem to be better equipped with regard to personal attributes such as self-conﬁdence and the will to work. However, in many instances, their general mathematical attributes such as algebraic manipulation skills and their general mastery of mathematical writing are worse than those of students in the past. There are also areas where their content knowledge is either lacking or unexpectedly shallow. It therefore appears that these students have improved personal attributes but not necessarily the knowledge and mathematical skills to back them up. Some recommendations are made with regard to handling the situation. It is clear that the new school system necessitates changes at school level with a view to university level in order to ensure a transition that is surmountable.
Gambling strategies for random sequences
Authors: Davie George
Published: August 2012

There is a general consensus that it is not possible to gamble successfully against a random se-quence. This consensus is based on results from probability theory that all gambling systems arein some sense futile and the idea that at any stage of the sequence, the next outcome is entirelyunpredictable.
The effect of statistical analytical measurement variations on the plant control parameters and production costs in cement manufacturing – a case study
Authors: Love A. D.
Published: August 2012

Raw materials used in cement manufacturing normally have varying chemical compositions and require regular analyses for plant control purposes. This is achieved by using several analytical instruments, such as XRF and ICP. The values obtained for the major elements Ca, Si, Fe and Al, are used to calculate the plant control parameters Lime Saturation Factor (LSF), Silica Ratio (SR) and Alumina Modulus (AM). These plant control parameters are used to regulate the mixing and blending of various raw meal components and to operate the plant optimally. Any errors and large ﬂuctuations in these plant parameters not only inﬂuence the quality of the cement produced, but also have a major effect on the cost of production of cement clinker through their inﬂuence on the energy consumption and residence time in the kiln. This paper looks at the role that statistical variances in the analytical measurements of the major elements Ca, Si, Fe and Al can have on the ultimate LSF, SR and AM values calculated from these measurements. The inﬂuence of too high and too low values of the LSF, SR and AM on clinker quality and energy consumption is discussed, and acceptable variances in these three parameters, based on plant experiences, are established. The effect of variances in the LSF, SR and AM parameters on the production costs is then analysed, and it is shown that variations of as large as 30% and as little as 5% can potentially occur. The LSF calculation incorporates most chemical elements and therefore is prone to the largest number of variations due to statistical variances in the analytical determinations of the chemical elements. Despite all these variations in LSF values they actually produced the smallest inﬂuence on the production cost of the clinker. It is therefore concluded that the LSF value is the most practical parameter for plant control purposes.
Biodiversity in agricultural soils, sustainable plant production and control of plant pathogens
Authors: Reinecke A. J. , Reinecke S. A.
Published: August 2012

Pathogens Soils are very heterogeneous substrates providing an environmental matrix with varying spatial and temporal gradients of pH, organic carbon, particle size distribution and moisture content. Chemical, physical as well as biological factors are operational and soil includes a vast variety of soil-dwelling invertebrates and microbes that interact with each other and the environment to inﬂuence plant productivity directly and indirectly. A review of recent literature on the role of soil biodiversity highlights the important role of soil invertebrates, notably earthworms, in inﬂuencing soil characteristics and soil borne plant pathogens. Earthworms are widely recognized as having critical functions in soil in regulating key processes that impact favourably on plant productivity and simultaneously eliminating or reducing soil borne diseases. The aim of this review is ﬁrstly to contribute towards a clariﬁcation of the role of soil biodiversity in general and to focus speciﬁcally on that of earthworms and their role in inﬂuencing plant pathogens and parasites. Evidence is provided that their activities can support plant productivity and suppress pathogens. Once the nature and extent of their role is better known and they are conﬁrmed to support plant productivity to the extent that many soil biologists believe, the next logical step is to utilize knowledge of their ecology to create and manage favourable environmental conditions to ensure their survival and activity in agricultural soils. Agricultural management practices that favour soil organisms are also reviewed. Implementing these will make the services of soil biota available to improve and sustain agro-ecosystems. This requires a better understanding of the preferences and tolerance ranges of these organisms and their interactions before we can apply methodologies in general to manipulate environmental conditions to maximise the beneﬁts that they may offer.
Studentesimposium in die Natuurwetenskappe 30 Oktober 2009, Universiteit van die Vrystaat ’n Seleksie van referaatopsommings
Authors: Office Editorial
Published: August 2012

Geen abstrak
Important factors for local ecotype selection in restoration applications
Authors: Van den Berg Loraine , Kellner Klaus
Published: August 2012

The type of restoration application in degraded natural rangelands will depend on the degree of degradation. Degraded areas that are beyond the threshold of natural recovery normally need active restoration interventions. This includes the disturbance of the soil surface or the removal of undesired and alien species to reduce the competitive effect on the existing vegetation. One of the main goals of restoration in degraded arid and semi-arid rangelands is to increase the grazing capacity for livestock production. Active restoration interventions include re-seeding or re-vegetation with local ecotype selected species, adapted to the speciﬁc soil and climatic conditions of the area. To facilitate seed germination and seedling establishment, the restoration practice should also include protection measures such as brush packing or any cover by other organic matter. The timing of re-seeding is dependent on the seasonality and precipitation, especially in areas where rainfall events are erratic and unpredictable. Re-seeding of large degraded areas with speciﬁc ecotype selected species greatly depends on the availability of seed. This is a major limiting factor as most seed available from seed merchants are used for cultivated pastures, and do not include seed of local ecotype species that are adapted to a certain environment. To collect large quantities of seed represented by a speciﬁc habitat is very labor intensive and often not cost effective. Furthermore, if local ecotype selected seed is used, the quality, viability and purity are often not of a high standard, leading to poor restoration results. Although the economic implication and short term results of a restoration application are often regarded as determining factors, the ecological importance and improvement in the range condition should not be underestimated. Restoration applications have to be implemented according to a predetermined plan and should include monitoring and sound long-term management principles.
Low-frequency magnetic field fluctuations in Earth's plasma environment observed by THEMIS
Authors: Guicking L. , Glassmeier K.-H. , Auster H.-U. , Narita Y. , Kleindienst G.
Published: August 2012

Abstract. Low-frequency magnetic wave activity in Earth's plasma environment was determined based on a statistical analysis of THEMIS magnetic field data. We observe that the spatial distribution of low-frequency magnetic field fluctuations reveals highest values in the magnetosheath, but the observations differ qualitatively from observations at Venus presented in a previous study since significant wave activity at Earth is also observed in the nightside magnetosheath. Outside the magnetosheath the low-frequency wave activity level is generally very low. By means of an analytical streamline model for the magnetosheath plasma flow, we are able to investigate the spatial and temporal evolution of wave intensity along particular streamlines in order to characterise possible wave generation mechanisms. We observe a decay of wave intensity along the streamlines, but contrary to the situation at Venus, we obtain good qualitative agreement with the theoretical concept of freely evolving/decaying turbulence. Differences between the dawn region and the dusk region can be observed only further away from the magnetopause. We conclude that wave generation mechanisms may be primarily attributed to processes at or in the vicinity of the bow shock. The difference with the observations of the Venusian magnetosheath we interpret to be the result of the different types of solar wind interaction processes since the Earth possesses a global magnetic field while Venus does not, and therefore the observed magnetic wave activities may be caused by diverse magnetic field controlled characteristics of wave generation processes.
Organic matter exudation by Emiliania huxleyi under simulated future ocean conditions
Authors: Borchard C. , Engel A.
Published: August 2012

Abstract. Emiliania huxleyi (strain B 92/11) was exposed to different nutrient supply, CO2 and temperature conditions in phosphorus controlled chemostats to investigate effects on organic carbon exudation and partitioning between the pools of particulate organic carbon (POC) and dissolved organic carbon (DOC). 14C incubation measurements for primary production (PP) and extracellular release (ER) were performed. Chemical analysis included the amount and composition of high molecular weight (>1 kDa) dissolved combined carbohydrates (HMW-dCCHO), particulate combined carbohydrates (pCCHO) and the carbon content of transparent exopolymer particles (TEP-C). Applied CO2 and temperature conditions were 300, 550 and 900 μatm pCO2 at 14 °C, and additionally 900 μatm pCO2 at 18 °C simulating a greenhouse ocean scenario. Enhanced nutrient stress by reducing the dilution rate (D) from D = 0.3 d−1 to D = 0.1 d−1 (D = μ) induced the strongest response in E. huxleyi. At μ = 0.3 d−1, PP was significantly higher at elevated CO2 and temperature and DO14C production correlated to PO14C production in all treatments, resulting in similar percentages of extracellular release (PER; (DO14C production/PP) × 100) averaging 3.74 ± 0.94%. At μ = 0.1 d−1, PO14C production decreased significantly, while exudation of DO14C increased. Thus, indicating a stronger partitioning from the particulate to the dissolved pool. Maximum PER of 16.3 ± 2.3% were observed at μ = 0.1 d−1 at elevated CO2 and temperature. While cell densities remained constant within each treatment and throughout the experiment, concentrations of HMW-dCCHO, pCCHO and TEP were generally higher under enhanced nutrient stress. At μ = 0.3 d−1, pCCHO concentration increased significantly with elevated CO2 and temperature. At μ = 0.1 d−1, the contribution (mol % C) of HMW-dCCHO to DOC was lower at elevated CO2 and temperature while pCCHO and TEP concentrations were higher. This was most pronounced under greenhouse conditions. Our findings suggest a stronger transformation of primary produced DOC into POC by coagulation of exudates under nutrient limitation. Our results further imply that elevated CO2 and temperature will increase exudation by E. huxleyi and may affect organic carbon partitioning in the ocean due to an enhanced transfer of HMW-dCCHO to TEP by aggregation processes.
Mesozooplankton community development at elevated CO2 concentrations: results from a mesocosm experiment in an Arctic fjord
Authors: Niehoff B. , Knüppel N. , Daase M. , Czerny J. , Boxhammer T.
Published: August 2012

Abstract. The increasing CO2 concentration in the atmosphere caused by burning fossil fuels leads to increasing pCO2 and decreasing pH in the world oceans. These changes may have severe consequences for marine biota, especially in cold-water ecosystems due to higher solubility of CO2. However, studies on the response of mesozooplankton communities to elevated pCO2 are yet lacking. In order to test whether abundance and taxonomic composition change with pCO2, we have sampled nine mesocosms, which were deployed in Kongsfjorden, an Arctic fjord at Svalbard, and were adjusted to eight CO2 concentrations, initially ranging from 185 μatm to 1420 μatm. Samples were taken weekly over a six-week period with an Apstein net (55 μm mesh size) in all mesocosms and the surrounding fjord. In addition, sediment trap samples, taken every second day in the mesocosms, were analyzed to account for losses due to vertical migration and mortality. The taxonomic analysis revealed that meroplanktonic larvae (cirripeds, polychaetes, bivalves, gastropod, and decapods) dominated in the mesocosms while copepods (Calanus spp., Oithona similis, Acartia longiremis and Microsetella norvegica) were found in lower abundances. In the fjord copepods prevailed for most of our study. With time, abundance and taxonomic composition developed similarly in all mesocosms; the pCO2 had no significant effect on the overall community structure. However, single taxa responded to elevated CO2 concentrations. The ratio of cirripedia nauplii to cypris larvae, the next developmental stage, in the sediment traps averaged over the entire experiment increased with pCO2 and this suggests that increased pCO2 may have delayed their development. Also, the number of bivalves, averaged over the experimental period, decreased significantly with increasing pCO2. The nature of the CO2 effect, either direct or indirect, remains open and needs to be addressed in future.
Modeling benthic-pelagic nutrient exchange processes and porewater distributions in a seasonally-hypoxic sediment: evidence for massive phosphate release by Beggiatoa?
Authors: Dale A. W. , Bertics V. J. , Treude T. , Sommer S. , Wallmann K.
Published: August 2012

Abstract. This study presents benthic data from 12 samplings from February to December 2010 in a 2 m deep channel in the southwest Baltic Sea. In winter, the distribution of solutes in the porewater was strongly modulated by bioirrigation which efficiently flushed the upper 1 cm of sediment, leading to concentrations which varied little from bottom water values. Solute pumping by bioirrigation fell sharply in summer as the bottom waters became severely hypoxic (<2 μM O2). At this point the giant sulfide-oxidizing bacteria Beggiatoa was visible on surface sediments. Despite an increase in O2following mixing of the water column in November, macrofauna remained absent until the end of the sampling. Contrary to expectations, metabolites such as dissolved inorganic carbon, ammonium and hydrogen sulfide did not accumulate in the porewater during the hypoxic period when bioirrigation was absent, but instead tended toward bottom water values. This was taken as evidence for episodic bubbling of methane gas out of the sediment acting as an abiogenic irrigation process. Escaping bubble may provide a pathway for enhanced nutrient release to the bottom water and exacerbate the feedbacks with hypoxia. Subsurface dissolved phosphate (TPO4) peaks in excess of 400 μM developed in autumn resulting in a very large diffusive TPO4 flux to the water column of 0.7 ± 0.2 mmol m−2 d−1. The model was not able to simulate this TPO4 source as release of iron-bound P (Fe–P) or organic P. As an alternative hypothesis, the TPO4 peak was reproduced using new kinetic expressions that allow Beggiatoa to take up porewater TPO4 and accumulate an intracellular P pool during periods with oxic bottom waters. TPO4 is then released during hypoxia, as previous published results with sulfide-oxidizing bacteria indicate. The TPO4 added to the porewater over the year by organic P and Fe–P is recycled though Beggiatoa, meaning that no additional source of TPO4 is needed to explain the TPO4 peak. Further experimental studies are needed to strengthen this conclusion and rule out Fe–P and organic P as candidate sources of ephemeral TPO4 release. A measured C/P ratio of <20 for the diffusive flux at the sediment surface during hypoxia directly demonstrates preferential release of P relative to C under low oxygen bottom waters. Our results suggest that sulfide oxidizing bacteria act as phosphorus capacitors in systems with oscillating redox conditions, releasing massive amounts of TPO4 in a short space of time and dramatically increasing the internal loading of TPO4 in overlying waters.
Statistical framework for evaluation of climate model simulations by use of climate proxy data from the last millennium – Part 1: Theory
Authors: Sundberg R. , Moberg A. , Hind A.
Published: August 2012

Abstract. A statistical framework for comparing the output of ensemble simulations from global climate models with networks of climate proxy and instrumental records has been developed, focusing on near-surface temperatures for the last millennium. This framework includes the formulation of a joint statistical model for proxy data, instrumental data and simulation data, which is used to optimize a quadratic distance measure for ranking climate model simulations. An essential underlying assumption is that the simulations and the proxy/instrumental series have a shared component of variability that is due to temporal changes in external forcing, such as volcanic aerosol load, solar irradiance or greenhouse gas concentrations. Two statistical tests have been formulated. Firstly, a preliminary test establishes whether a significant temporal correlation exists between instrumental/proxy and simulation data. Secondly, the distance measure is expressed in the form of a test statistic of whether a forced simulation is closer to the instrumental/proxy series than unforced simulations. The proposed framework allows any number of proxy locations to be used jointly, with different seasons, record lengths and statistical precision. The goal is to objectively rank several competing climate model simulations (e.g. with alternative model parameterizations or alternative forcing histories) by means of their goodness of fit to the unobservable true past climate variations, as estimated from noisy proxy data and instrumental observations.
Holocene climate variability in north-eastern Italy: potential influence of the NAO and solar activity recorded by speleothem data
Authors: Scholz D. , Frisia S. , Borsato A. , Spötl C. , Fohlmeister J. , Mudelsee M. , Miorandi R. , Mangini A.
Published: August 2012

Abstract. Here we present high-resolution stable isotope and lamina thickness profiles as well as radiocarbon data for the Holocene stalagmite ER 76 from Grotta di Ernesto (north-eastern Italy), which was dated by combined U-series dating and lamina counting. ER 76 grew between 8 ka (thousands of years before 2000 AD) and today, with a hiatus from 2.6 to 0.4 ka. Data from nine meteorological stations in Trentino show a significant influence of the North Atlantic Oscillation (NAO) on winter temperature and precipitation in the cave region. Spectral analysis of the stable isotope signals of ER 76 reveals significant peaks at periods of 110, 60–70, 40–50, 32–37 and around 25 a. Except for the cycle between 32 and 37 a all periodicities have corresponding peaks in power spectra of solar variability, and the 25-a cycle may correspond to NAO variability. This suggests that climate variability in northern Italy was influenced by both solar activity and the NAO during the Holocene. Six periods of warm winter climate in the cave region were identified. These are centred at 7.9, 7.4, 6.5, 5.5, 4.9 and 3.7 ka, and their duration ranges from 100 to 400 a. The two oldest warm phases coincide with the deposition of sapropel S1 in the Mediterranean Sea indicating that the climate in the cave region was influenced by this prominent pluvial phase in the Mediterranean area. For the younger warm phases it is difficult to establish a supra-regional climate pattern, and some of them may, thus, reflect regional climate variability. This highlights the complexity of regional and supra-regional scale Holocene climate patterns.
Reconstruction of temporal variations of evapotranspiration using instantaneous estimates at the time of satellite overpass
Authors: Delogu E. , Boulet G. , Olioso A. , Coudert B. , Chirouze J. , Ceschia E. , Le Dantec V. , Marloie O. , Chehbouni G. , Lagouarde J.-P.
Published: August 2012

Abstract. Evapotranspiration estimates can be derived from remote sensing data and ancillary, mostly meterorological, information. For this purpose, two types of methods are classically used: the first type estimates a potential evapotranspiration rate from vegetation indices, and adjusts this rate according to water availability derived from either a surface temperature index or a first guess obtained from a rough estimate of the water budget, while the second family of methods relies on the link between the surface temperature and the latent heat flux through the surface energy budget. The latter provides an instantaneous estimate at the time of satellite overpass. In order to compute daily evapotranspiration, one needs an extrapolation algorithm. Since no image is acquired during cloudy conditions, these methods can only be applied during clear sky days. In order to derive seasonal evapotranspiration, one needs an interpolation method. Two combined interpolation/extrapolation methods based on the self preservation of evaporative fraction and the stress factor are compared to reconstruct seasonal evapotranspiration from instantaneous measurements acquired in clear sky conditions. Those measurements are taken from instantaneous latent heat flux from 11 datasets in Southern France and Morocco. Results show that both methods have comparable performances with a clear advantage for the evaporative fraction for datasets with several water stress events. Both interpolation algorithms tend to underestimate evapotranspiration due to the energy limiting conditions that prevail during cloudy days. Taking into account the diurnal variations of the evaporative fraction according to an empirical relationship derived from a previous study improved the performance of the extrapolation algorithm and therefore the retrieval of the seasonal evapotranspiration for all but one datasets.
Structural damages observed in state buildings after Simav/Turkey earthquake occurred on 19 May 2011
Authors: Tama Y. S.
Published: August 2012

Abstract. Different levels of damages occurred in state buildings, especially in educational facilities, during the Simav earthquake (ML=5.7) on 19 May 2011. A site survey was carried out in the area after the earthquake, where six state buildings were examined in detail. The results of the survey showed that main reasons for the formation of damages in these buildings are the use of low strength concrete, insufficient reinforcement, inappropriate detailing, and low-quality workmanship. The investigated buildings were also evaluated by P25-rapid assessment method. The method demonstrates that two of the buildings in question are in "high risk band"; the other two fall into "detailed evaluation band", and the rest are in the "low risk band". This figure also matches with the damages observed in the site survey.
Creating a Financially Feasible High-Performance Metropolitan Transportation System
Authors: DeCorla-Souza Patrick
Published: August 2012

This paper assesses a strategy to alleviate recurring congestion on metropolitan highway systems by adding "dynamic" capacity during peak periods, using shoulders as travel lanes, along with variable peak-period user charges levied on all lanes, to manage demand and pay for the capacity improvements and complementary multimodal investments. It presents an analysis of the traffic, delay, fuel consumption, CO2 emissions, and cost and revenue impacts. The paper then discusses various technical and public acceptance issues with regard to the concept, and how these issues might be addressed.
Studying the Tailgating Issues and Exploring Potential Treatment
Authors: Song Miao , Wang Jyh-Hone
Published: August 2012

A human factors study consisting of a vehicle headway analysis and a questionnaire survey was conducted in Rhode Island (RI) to investigate tailgating issues and possible means for tailgating treatment. Vehicle headways were collected from highway surveillance videos and serious tailgating issues were identified on RI highways. The results of the questionnaire survey further confirmed the observations made in the vehicle headway analysis that most RI drivers maintained insufficient vehicle headways on highways. Among a few tailgating treatments presented in the survey, most subjects preferred a system consisting of equally spaced, white horizontal bars marked on pavement and overhead graphic-aided dynamic message signs.
Aircraft Leasing and Its Effects on Air Carriers Debt Burdens: A Comparison Over the Past Several Decades
Authors: Gritta Richard , Lippman Ellen
Published: August 2012

Leasing has always been an important source of finance to carriers in the U.S. airline industry. In the 1960-1970s, many carriers employed a type of lease called a financial lease as an alternative source of funds to acquire aircraft. It had a major advantage over purchasing the aircraft. It was "off-the-balance sheet financing," as the obligations under this type of lease appeared only in the footnotes to carrier balance sheets. Little use was made of short-term lease agreements during this period. The situation has changed radically over the past three decades. In 1976, the Financial Accounting Standards Board issued SFAS No. 13 defining specific criteria for capital leases that required the reporting of these "off-the-balance sheet financing" as both a leasehold asset and a long-term liability recorded under the long-term debt section of the balance sheet. In response, the air carriers substantially altered the way they finance airplanes. Carriers began to lease more and more of their aircraft, but they did so by structuring leases as shorter-term operating leases, which are not reported on companies' balance sheets. By strategically violating the criteria for capital leases, the air carriers once again pushed the leases off the balance sheet. The purpose of this research is to demonstrate the switch in the characteristics of aircraft leasing and to quantify the effects of such leases on air carrier debt burdens. In the process it will be argued that "debt is debt" no matter how it is structured. The paper updates two research studies by the authors to 2008.
Economic Analysis of Biomass Supply Chains: A Case Study of Four Competing Bioenergy Power Plants in Northwestern Ontario
Authors: Alam Md. Bedarul , Pulkki Reino , Shahi Chander , Upadhyay Thakur Prasad
Published: August 2012

Supply chain optimization for biomass-based power plants is an important research area due to greater emphasis on green energy sources. This paper develops and applies two optimization models to analyze the impacts of biomass competition on cost structures and gross margins for four competing biomass-based power plants in northwestern Ontario. Model scenarios are run to study the impacts of changes in parameters relevant to biomass type and processing technology, and prices of inputs and outputs on procurement costs. Cost minimization model shows that per unit procurement costs are directly proportional to the size of the power plants in all scenarios. Profit maximization model, on the other hand, shows that FMUs that are closer to the power plants make higher gross margins. However, the margins significantly increase for FMUs that are close to the power plants potentially offering higher prices. The variations in costs and gross margin structures under various model scenarios are explained by location of depletion cells relative to power plants, availability of each type of biomass in depletion cells, biomass demands, and differential processing costs for two types of biomass. These results can aid decision makers to make improved decisions related to biomass supply chains for bioenergy production.
Physiological and Biochemical Responses to Drought Stress and Subsequent Rehydration in the Symbiotic Association Peanut-Bradyrhizobium sp.
Authors: Furlan Ana , Llanes Analía , Luna Virginia , Castro Stella
Published: August 2012

Drought stress is one of the most important environmental factors that regulate plant growth and development and limit its production. Peanut (Arachis hypogaea L.) is an agriculturally valuable plant with widespread distribution in the world serving as a subsistence food crop as well as a source of various food products. The aims of this work were to evaluate growth and nodulation as well as some physiological and biochemical stress indicators in response to drought stress and subsequent rehydration in the symbiotic association peanut-Bradyrhizobium sp. SEMIA6144. Drought stress affected peanut growth reducing shoot dry weight, nodule number, and dry weight as well as nitrogen content, but root dry weight increased reaching a major exploratory surface. Besides, this severe water stress induced hydrogen peroxide production associated with lipid and protein damage; however, the plant was able to increase soluble sugar and abscisic acid contents as avoidance strategies to cope with drought stress. These physiological and biochemical parameters were completely reversed upon rehydration, in a short period of time, in the symbiotic association peanut-Bradyrhizobium sp. Thus, the results provided in this work constitute the initial steps of physiological and biochemical responses to drought stress and rehydration in this nodulated legume.
Sexual Knowledge among High School Students in Northwestern Iran
Authors: Malek Ayyoub , Shafiee-Kandjani Ali Reza , Safaiyan Abdolrasool , Abbasi-Shokoohi Hamid
Published: August 2012

Objectives. Regarding the importance of sexual desire in adolescence period and public and parental concerns about it and considering the lack of studies on sexual knowledge especially in adolescents in Iran, this study was conducted to evaluate the sexual issues in high school girls and boys. Patients and Methods. The cross-sectional study was performed on 2700 high school students. Students were selected through a multi-staged randomized sampling method in Tabriz and by the convenience method in Ardabil and Urmia. Data collection tool was a questionnaire including knowledge questions and measured by a three-point scale. Data were statistically analyzed with SPSS version 11.5 software. Results. 11.8% of the students had a low sexual knowledge, 46.7% had average and 41.5% had a high one. There was no significant difference between male and female students' general sexual knowledge. The highest knowledge was about being aware of the religious rules concerning sex. Conclusion. Adolescents should be trained and acquire information about the different aspects of sexual issues. Female adolescents especially need to be educated about puberty physiology, fertility physiology and STDs.
Prenatal Exposure to Maternal Cigarette Smoke and Offspring Risk of Excess Weight Is Independent of Both Birth Weight and Catch-Up Growth
Authors: Gravel Jonathan , Potter Beth , Dubois Lise
Published: August 2012

Prenatal exposure to maternal cigarette smoke (PEMCS) is one of the most common insults to the developing fetus and has consistently emerged as an important risk factor for excess weight in the offspring. However, no consensus exists on the mechanism of action or duration of impact. This study seeks to further examine the role of PEMCS on overweight status of children up to age 10. Mother and child pairs (n=1183) were analysed from the Québec Longitudinal Study of Child Development (QLSCD) (1998–2010). Multivariable logistic regression models were used to control for confounders and assess mediation. PEMCS was associated with overweight status at age 10 (OR: 1.70; 95% CI: 1.20–2.43) after adjustment for early life exposures and childhood behaviours. This relationship remained robust after adjustment for birth weight and catch-up growth. Other significant predictors included APGAR score, mother’s immigrant and weight status, family type and child energy intake. The elevated risk of excess weight among the offspring of smoking mothers was not accounted for by other known determinants, and PEMCS appears to play a role independent of birth weight and catch-up growth. Our research suggests that young mothers may be an important audience for targeting preventive strategies.
Mapping and Comparing Mobilisation Strategies Throughout Europe: Towards Making Lifelong Learning a Reality
Authors: Broek Simon , Buiskool Bert-Jan
Published: August 2012

Making lifelong learning a reality has been a recurring theme within European policy making. Increasing participation of adults can help overcome various Europe-wide challenges, amongst others, skills redundancy, the high number of low-skilled workers in Europe, the high level of early school leaving, and literacy and numeracy difficulties. In order to surmount these challenges governments need to take action to improve their adult learning systems.

Throughout Europe a wide variety of mobilisation instruments is deployed aiming at increasing and widening participation of adults (and specific target groups) in learning. However, less is known about which instrument is most effective in addressing specific target groups and learning barriers. The key question to be answered in this article is what kind of practices work for what kind of adults and under which conditions. Subsequently, this article addresses the various mobilisation strategies and how they relate to different work domains in the adult learning sector and identifies the stimulating conditions for implementing adult learning measures to increase and widen participation. This contextualising of practices could help policy makers, project developers, evaluators and researchers to better structure the intervention logic of policy measures.

This article is based on a Europe-wide study of the European Commission examining the impact of ongoing reforms in the adult learning sector in Europe.
Adult Education in Malta: Challenges and Prospects
Authors: Mayo Peter
Published: August 2012

Lifelong learning has long been a topic of discussion in Malta but, as this article shows, barriers to participation continue to exist. This article outlines the historical and economic changes that have led Malta to its present situation where adult education largely focuses on employment skills. Although available through a variety of channels, challenges still need to be met to ensure the participation of groups such as women, older people and immigrants.

This article advocates a national strategy for adult education within which a balance is struck between learning for employment and learning as a public good.
Short‐ and long‐term sunlight radiation and stroke incidence
Authors: Kent Shia T. , McClure Leslie A. , Judd Suzanne E. , Howard Virginia J. , Crosson William L. , Al‐Hamdan Mohammad Z. , Wadley Virginia G. , Peace Fredrick , Kabagambe Edmond K.
Published: August 2012

Objective:

Examine whether long‐ and short‐term sunlight radiation is related to stroke incidence.

Methods:

Fifteen‐year residential histories merged with satellite, ground monitor, and model reanalysis data were used to determine sunlight radiation (insolation) and temperature exposure for a cohort of 16,606 stroke and coronary artery disease‐free black and white participants aged ≥45 years from the 48 contiguous United States. Fifteen‐, 10‐, 5‐, 2‐, and 1‐year exposures were used to predict stroke incidence during follow‐up in Cox proportional hazard models. Potential confounders and mediators were included during model building.

Results:

Shorter exposure periods exhibited similar, but slightly stronger relationships than longer exposure periods. After adjustment for other covariates, the previous year's monthly average insolation exposure below the median gave a hazard ratio (HR) of 1.61 (95% confidence interval [CI], 1.15–2.26), and the previous year's highest compared to the second highest quartile of monthly average maximum temperature exposure gave an HR of 1.92 (95%, 1.27–2.92).

Interpretation:

These results indicate a relationship between lower levels of sunlight radiation and higher stroke incidence. The biological pathway of this relationship is not clear. Future research will show whether this finding stands, the pathway for this relationship, and whether it is due to short‐ or long‐term exposures. ANN NEUROL 2013
25‐Hydroxyvitamin D and symptomatic ischemic stroke: An Original Study and Meta‐Analysis
Authors: Brøndum‐Jacobsen Peter , Nordestgaard Børge G. , Schnohr Peter , Benn Marianne
Published: August 2012

Objective:

We tested the hypothesis that low plasma concentrations of 25‐hydroxyvitamin D are associated with increased risk of symptomatic ischemic stroke in the general population.

Methods:

We measured plasma 25‐hydroxyvitamin D in 10,170 individuals from the general population, the Copenhagen City Heart Study. During 21 years of follow‐up, 1,256 and 164 persons developed ischemic and hemorrhagic stroke, respectively. In a meta‐analysis of ischemic stroke, we included 10 studies, 58,384 participants, and 2,644 events.

Results:

Stepwise decreasing plasma 25‐hydroxyvitamin D concentrations were associated with stepwise increasing risk of ischemic stroke both as a function of seasonally adjusted percentile categories and as a function of clinical categories of 25‐hydroxyvitamin D (p for trend ≤ 2 × 10−3). In a Cox regression model comparing individuals with plasma 25‐hydroxyvitamin D concentrations between the 1st and 4th percentiles to individuals with 25‐hydroxyvitamin D concentrations between the 50th and 100th percentiles, multivariate adjusted hazard ratio of ischemic stroke was 1.82 (95% confidence interval, 1.41–2.34). Comparing individuals with clinical categories of severe vitamin D deficiency (<25.0nmol/l [<10.0ng/ml]) to individuals with optimal vitamin D status (≥75.0nmol/l [≥30.0ng/ml]), the multivariate adjusted hazard ratio of ischemic stroke was 1.36 (1.09–1.70). 25‐Hydroxyvitamin D concentrations were not associated with risk of hemorrhagic stroke. In a meta‐analysis comparing lowest versus highest quartile of 25‐hydroxyvitamin D concentrations, the multivariate adjusted odds ratio of ischemic stroke was 1.54 (1.43–1.65) with a corresponding hazard ratio of 1.46 (1.35–1.58) in prospective general population studies.

Interpretation:

In this large population‐based prospective study, we observed stepwise increasing risk of symptomatic ischemic stroke with decreasing plasma 25‐hydroxyvitamin D concentrations. This finding was substantiated in a meta‐analysis. ANN NEUROL 2013.
A provisional strategy for treating true bifurcation lesions employing a scoring balloon for the side branch
Authors: Weisz Giora , Metzger D. Christopher , Liberman Henry A. , O'Shaughnessy Charles D. , Douglas John S. , Turco Mark A. , Mehran Roxana , Gershony Gary , Leon Martin B. , Moses Jeffrey W.
Published: August 2012

Background

The provisional approach for bifurcation stenting with side‐branch balloon angioplasty is associated with dissections and suboptimal results requiring kissing balloon techniques or bailout stenting. We hypothesized that using a scoring balloon for the side branch and a drug‐eluting stent for the main vessel might improve outcomes of true bifurcation lesions.

Methods and Results

A total of 93 patients with complex bifurcations were enrolled in a multicenter, single‐arm, prospective clinical trial. A drug‐eluting stent was deployed in the main vessel following dilatation of the side‐branch stenosis with a scoring balloon. The overall angiographic success rate was 93.5%, and procedural success rate was 91.4%. The final diameter stenosis was 13.9% ± 7.2% for the main vessel and 33.3% ± 22.9% for the side branch. Crossover to stent deployment in the side branch was required in 10.8%. The postscoring balloon dissection rate was 8.2% and 6% (all ≤ class C) for the main vessel and side branch respectively, which was reduced to 1.1 and 2.1% poststenting. At 9‐month follow‐up, the composite MACE rate [cardiac death, myocardial infarction, or target lesion revascularization (TLR)] was 5.4%, including a TLR rate of 3.3% (1.1% from hospital discharge to 9 months).

Conclusion

The 9‐month results of the AGILITY trial support a simple provisional strategy for treating complex true bifurcation lesions with deployment of a drug‐eluting stent in the main vessel after dilatation of the side‐branch vessel with a scoring balloon. This strategy was associated with excellent and safe procedural results, a low rate of crossover to side‐branch stenting, and favorable outcomes. © 2013 Wiley Periodicals, Inc.
Feasibility and safety of transcatheter closure of atrial septal defects with deficient posterior rim
Authors: Papa Marco , Gaspardone Achille , Fragasso Gabriele , Sidoti Federica , Agricola Eustachio , Gioffrè Gaetano , Iamele Maria , Margonato Alberto
Published: August 2012

Objectives

To evaluate the feasibility and safety of percutaneous closure of complex secundum‐type atrial septal defects (ASD) in patients with posterior‐inferior rim deficiency.

Background

Transcatheter approach is the method of choice for ASD closure; however, up to now 20% of the defects are not considered suitable for percutaneous intervention because of the lack of surrounding rims, especially the posterior‐inferior.

Methods

A total of 268 patients were evaluated between March 2005 and April 2011 for ASD closure. Twenty‐four patients (9%) were not considered suitable for a percutaneous intervention and referred to surgery due to inadequate rims or a large defect diameter. Out of the remaining 244 patients, 25 (10,2%) had posterior‐inferior rim deficiency and represent our study group.

Results

After failure of the conventional approach, alternative techniques were attempted. In 16 patients, an adjusted deployment and alignment maneuver approach was successful. In 5 other patients, a slide out technique was successfully performed by exploiting the right upper pulmonary vein. Finally in the remaining 4 patients, ASD closure was obtained by completely re‐orienting the system with a jugular approach. No peri‐procedural complications occurred, and at 12‐month transesophageal echocardiography evaluation no residual shunt could be detected.

Conclusions

Our data show the feasibility of percutaneous approach for ASD closure in presence of a deficient posterior‐inferior rim. The procedural success is strictly related to correct sizing and demonstration of a balloon notch on fluoroscopy. Long‐term follow‐up supports efficacy of the procedure in these selected cases. © 2012 Wiley Periodicals, Inc.
Incidence of patent foramen ovale and migraine headache in adults with congenital heart disease with no known cardiac shunts
Authors: Volman Marat , Mojadidi M. Khalid , Gevorgyan Rubine , Kaing Amy , Agrawal Harsh , Tobis Jonathan
Published: August 2012

The purpose of this study was to understand why patients with adult congenital heart disease (CHD) but no obvious shunt have an increased frequency of migraine headaches (MH). CHD patients with no known cardiac shunts (CHD‐NKS), based on their echocardiographic or angiographic procedures, were tested for a right‐to‐left shunt using agitated saline contrast transcranial Doppler (TCD). Medical records of 2,920 patients from the UCLA Adult CHD Center were screened to participate in a study to evaluate the prevalence of MH in adults with CHD; 182 patients (6.23%) had CHD‐NKS; of these, 60 (30%) underwent a TCD; 23 (38%) tested positive and 37 (62%) tested negative for a right‐to‐left shunt (P = 0.01 compared with controls). The frequency of MH was 43% in CHD‐NKS compared with 11% in controls (P < 0.0001). TCD demonstrated right‐to‐left shunting in approximately 2/3 of patients with pulmonary stenosis, the Marfan syndrome and congenitally corrected transposition of great vessels, 1/4 of patients with bicuspid aortic valve, 1/5 of patients with mitral valve prolapse and all patients with Ebstein's anomaly. Approximately half of these experienced MH. Patients who had MH did not show a higher frequency of right‐to‐left shunt when compared with patients without MH (P = 0.57). In conclusion, CHD patients with conditions usually not associated with a shunt have a higher than expected prevalence of PFO which permits intermittent right‐to‐left shunting undetected by standard non‐contrast TTE and TEE; the increased prevalence of right‐to‐left shunting may partially explain the higher than expected frequency of migraines. © 2012 Wiley Periodicals, Inc.