1,186 research outputs found

    Volatility of car ownership, commutingmode and time in the UK

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    This paper has two objectives: to examine the volatility of travel behaviour over timeand consider the factors explaining this volatility; and to estimate the factors determiningcar ownership and commuting by car. The analysis is based on observations of individualsand households over a period of up to eleven years obtained from the British HouseholdPanel Survey (BHPS). Changes in car ownership, commuting mode and commuting timeover a period of years for the same individuals/households are examined to determine theextent to which these change from year to year. This volatility of individual behaviour is ameasure of the ease of change or adaptation. If behaviour changes easily, policy measuresare likely to have a stronger and more rapid effect than if there is more resistance tochange. The changes are ?explained? in terms of factors such as moving house, changingjob and employment status. The factors determining car ownership and commuting by carare analysed using a dynamic panel-data models

    Land use and mobility

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    This paper analyses the effects of land use characteristics on mode choice and carownership. The study is based on a large sample of individuals from the National TravelSurvey of Great Britain for the years 1989-91 and 1999-2001. Land use characteristics aredefined as population density, size of the municipality, accessibility to public transport andlocal amenities, such as shops and services. Mode choice (shares of total travel by car,public transport and walking) and car ownership are modelled using multinomial andbinomial logit models respectively, which include a large number of socio-economicfactors (income, age, gender, household structure and employment status) as well as landuse indicators. The estimation results strongly support the importance of the land usefactors considered on mode choice and car ownership

    Effects of green manure crops on short-term nitrogen availability in organic sweet corn systems : a thesis presented in partial fulfilment of the requirements for the degree of Master of Applied Science in Soil Science

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    In the Gisborne Region of New Zealand (NZ) many organic sweet corn growers use a range of winter green manure crops as a means of maintaining and improving soil fertility, particularly the availability of soil N. Some debate exists as to the most suitable green manure crops and their effectiveness at improving short-term N availability for subsequent sweet corn crops. Two field trials were conducted in the Gisborne Region to assess the effectiveness of four winter green manure crops using a subsequent sweet corn crop to evaluate N availability. Two sites, Site-A at Tekaraka and Site-B at Tolaga Bay, with BIO-GROW NZ organic certification were used in this study. A Latin Square trial design was used at each site consisting of 25 plots made up of five replicates of each of the following five treatments: control (bare soil), blue lupin (Lupinus angustifolus), mustard (Brassica sp.), mustard/blue lupin mix and annual ryegrass (Lolium multiflorum). Just prior to the soil incorporation of green manure treatments (early-mid September 1997), the lupin crop had the highest N concentration and N accumulation levels of 2.1% N and 156 kg N ha-1, respectively, at Site-A and 2.1% N and 173 kg N ha-1, respectively at Site-B. Soil incorporation of green manure treatments significantly influenced soil (0-150 mm) mineral N (nitrate and ammonium) levels measured at sweet corn emergence (30 November 1997) and at 51/2 weeks post emergence. At sweet corn emergence the lupin, mustard/lupin mix, mustard, control and ryegrass treatments resulted in soil mineral N values of 68, 66, 57, 51 and 29 kg.N.ha-1, respectively, at Site-A and 118, 118, 91, 81 and 54 kg.N.ha-1, respectively, at Site B. At both sites, the lupin and mustard/lupin mix treatments resulted in soil mineral N levels significantly higher than the control treatment. In contrast, the ryegrass treatment resulted in soil mineral N levels significantly lower than the control treatment. These treatment effects were related to green manure crop N concentrations just prior to soil incorporation. On average over both sites, the lupin and mustard/lupin mix treatments, which had high DM yields (7900 kg and 6500 kg.DM.ha-1 respectively), had the highest N concentrations (2.0% and 2.1% N respectively). The ryegrass treatment, which also accumulated a high average DM yield (6200 kg.DM.ha-1), contained the lowest average N concentration of only 1.1% N. Sweet corn N accumulation at harvest was also significantly influenced by green manure treatments. At both sites, ryegrass significantly reduced sweet corn N accumulation compared with all other treatments, being 44% and 36% lower than control treatment value of 117 kg.N.ha-1. At Site-A, the lupin, mustard/lupin and mustard treatment effects on sweet corn N accumulation were not different from that of the control treatment at final harvest. However, at Site-B the lupin and mustard/lupin mix treatments did produce sweet corn N accumulation levels significantly higher than the control treatment; being 21% and 18% higher than the control value of 102 kg.N.ha-1, respectively. Compared to the control treatment sweet corn yield (17.3 t ha-1 averaged over both sites), none of the four green manure treatments improved sweet corn yield even though the lupin and mustard/lupin mix treatments both increased soil N availability and sweet corn N accumulation. Soil moisture limitations probably restricted yield potentials. However, the ryegrass treatment detrimentally affected sweet corn yields at both sites. When compared to the control treatment reductions of 64% and 48% at Site-A and Site-B, respectively, were measured. Soil mineral N (0-150 mm) tested early in the sweet corn growing season gave a better relationship with sweet corn N accumulation and yield compared with the incubation tests used. Short-term soil incubation tests, conducted under aerobic and anaerobic conditions, were not useful as indicators of net N mineralisation as they did not relate well to actual soil N mineralisation or crop response. Although both the lupin and the mustard/lupin mix treatments had similar effects on soil N availability and sweet corn N accumulation, of the two the lupin treatment achieved a higher level of estimated N fixation. On average the estimated N fixation in the lupin treatment (98 kg N ha-1 averaged over both sites) was higher than N losses in harvested sweet corn ears (77 kg N ha-1 averaged over both sites). This positive N balance would help compensate for other possible N losses from the soil-plant system (ie. ammonia volatilisation or nitrate leaching). Overall, the lupin green manure treatment appears be the best crop in terms of improving short-term N availability for the subsequent sweet corn crop and for maintaining an N balance in the soil-plant system. But ultimately, the benefit of lupin as a green manure crop will also depend on environmental conditions and management practices

    Visual Media and ASD: Impact on Social Interactions of Adolescents

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    There’s a wealth of research that provides evidence of an association between visual media and behavior problems among typically developing children. However, no research was located that examines the association between these variables in adolescents with ASDs. This current study begins to fill this gap in literature while examining possible positive effects of visual media on social behavior through the following research question: What effect does visual media have on the social interactions of adolescents with autism spectrum disorders? The design of the present study was a cross-sectional, quantitative study in which twenty participants completed an online questionnaire. The present study found that adolescents with ASDs who had high language skills more frequently interacted with peers than adolescents with low language skills. This study also found that of adolescents who engage in visual media use weekly or more, 90% play video games, 85% use computers, 80% engage with Apps (via iPad/iPod/Kindle), 75% watch television, 35% use social media and 25% engage with other forms of visual media (DVDs, DS, and using iPad for Wikipedia) which is more than twice as often as another study (Mazurek et al., 2011). This study also showed that adolescents with ASDs who frequently use the computer have fewer interactions about visual media with their siblings. Future research should continue to explore the relationship between visual media and the social interactions of adolescents with ASDs. Interventions using visual media with adolescents with ASDs to help improve their social interactions, should be explored by social workers and other mental health professionals as an intervention

    Visual Media and ASD: Impact on Social Interactions of Adolescents

    Get PDF
    There’s a wealth of research that provides evidence of an association between visual media and behavior problems among typically developing children. However, no research was located that examines the association between these variables in adolescents with ASDs. This current study begins to fill this gap in literature while examining possible positive effects of visual media on social behavior through the following research question: What effect does visual media have on the social interactions of adolescents with autism spectrum disorders? The design of the present study was a cross-sectional, quantitative study in which twenty participants completed an online questionnaire. The present study found that adolescents with ASDs who had high language skills more frequently interacted with peers than adolescents with low language skills. This study also found that of adolescents who engage in visual media use weekly or more, 90% play video games, 85% use computers, 80% engage with Apps (via iPad/iPod/Kindle), 75% watch television, 35% use social media and 25% engage with other forms of visual media (DVDs, DS, and using iPad for Wikipedia) which is more than twice as often as another study (Mazurek et al., 2011). This study also showed that adolescents with ASDs who frequently use the computer have fewer interactions about visual media with their siblings. Future research should continue to explore the relationship between visual media and the social interactions of adolescents with ASDs. Interventions using visual media with adolescents with ASDs to help improve their social interactions, should be explored by social workers and other mental health professionals as an intervention

    Interplay between long non-coding RNAs and epigenetic machinery: emerging targets in cancer?

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    Of the diverse array of putative molecular and biological functions assigned to long non-coding RNAs (lncRNAs), one attractive perspective in epigenetic research has been the hypothesis that lncRNAs directly interact with the proteins involved in the modulation of chromatin conformation. Indeed, epigenetic modifiers are among the most frequent protein partners of lncRNAs that have been identified to date, of which histone methyltransferases and protein members of the Polycomb Repressive Complex PRC2 have received considerable attention. This review is focused on how lncRNAs interface with epigenetic factors to shape the outcomes of crucial biological processes such as regulation of gene transcription, modulation of nuclear architecture, X inactivation in females and pre-mRNA splicing. Because of our increasing knowledge of their role in development and cellular differentiation, more research is beginning to be done into the deregulation of lncRNAs in human disorders. Focusing on cancer, we describe some key examples of disease-focused lncRNA studies. This knowledge has significantly contributed to our ever-improving understanding of how lncRNAs interact with epigenetic factors of human disease, and has also provided a plethora of much-needed novel prognostic biomarker candidates or potential therapeutic targets. Finally, current limitations and perspectives on lncRNA research are discussed here. This article is part of a discussion meeting issue 'Frontiers in epigenetic chemical biology'

    Short-term effects of deep ploughing on soil C stocks following renewal of a dairy pasture in New Zealand

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    In New Zealand’s high producing permanent pastures the topsoil constitutes a large reservoir of soil organic carbon (SOC), which shows a marked stratification with depth. As consequence, sub-surface layers can contain 10 times less carbon than the surface soil. In permanent pastures with high carbon inputs, the formation and decomposition of these surface SOC stocks are often at equilibrium and C storage shows little change over time. Pastoral based dairy systems utilising ryegrass plus clover cultivars require renewal every 7-10 years to avoid reversion to less productive grasses. This may involve spring cultivation (either no-till, shallow till or full cultivation), summer forage cropping and autumn re-grassing. It has been hypothesised that SOC stocks can be increased by inverting the soil profile at pasture renewal through infrequent (once in 25-30 years) deep mouldboard ploughing (up to 30 cm depth). Increased C sequestration occurs when the new grass quickly rebuilds SOC stocks in the new topsoil (exposed low C sub-soil) at a rate faster than the decomposition of SOC in the rich former topsoil transferred to depth (now below 15 cm). However, benefits form accelerated C storage may be offset if crop and pasture production is adversely affected by the ploughing event (e.g., as result of compaction or excessive drainage). Hence, the aim of this work was to assess the short-term effects of infrequent inversion tillage of long-term New Zealand pastoral-based dairy soils under summer crop management and autumn re-grassing. An imperfectly drained Typic Fragiaqualf under dairy grazing was deep ploughed (approx. 25 cm) and re-sown with turnip in October 2016; other treatments included were shallow (< 10 cm) cultivation and no-till. The site was core sampled (0-40 cm) before cultivation and after 5 months of turnip growth to assess changes in SOC. Plant growth, herbage quality, and nutrient leaching were monitored during the 5-month period; root growth was assessed at the end of the crop rotation. Full cultivation transferred SOC below 10 cm depth, as expected. Soil bulk density decreased whereas root mass increased (10-20 cm depth; P < 0.05) under deep cultivation only. Besides, losses of mineral N were attenuated under deep tillage, resulting in a relative increase in crop yield. The potential for infrequent inversion tillage increasing soil C sequestration as a greenhouse gas (GHG) mitigation tool is currently being tested at other sites in New Zealand

    Overall fluctuating pressure levels on prospective space shuttle launch configurations at Mach numbers from 0.8 to 2.2

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    Overall fluctuating pressure levels of seven space shuttle launch configurations are presented. The model was a 4-percent-scale space shuttle vehicle, tested in both a 11- by 11-foot transonic wind tunnel and a 9- by 7-foot supersonic wind tunnel. Mach numbers varied from 0.8 to 2.2, and the angle of attack range was from -8 deg to 8 deg at angles of sideslip of -5 deg, and 5 deg. The model configurations included both series-burn and parallel-burn configurations, two canopy configurations, two positions of the orbiter nose relative to the HO tank nose and two HO tank nose-cone angles (15 deg and 20 deg). The fluctuating pressure levels are presented in three forms

    Shadowgraphs of air flow over prospective space shuttle configurations at Mach numbers from 0.8 to 1.4

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    Shadowgraphs of five space shuttle launch configurations are presented. The model was a 4 percent-scale space shuttle vehicle, tested in the 11- by 11-foot Transonic Wind Tunnel at Ames Research Center. The Mach number was varied from 0.8 to 1.4 with three angles of sideslip (0 deg, 5 deg and -5 deg) that were used in conjunction with three angles of attack (4 deg, -4 deg, and 0 deg). The model configurations included both series-burn and parallel-burn configurations, two canopy configurations, two positions of the orbiter nose relative to the HO tank nose, and two HO tank nose-cones angles (15 deg and 20 deg). The data consist entirely of shadowgraph photographs
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