Dry Matter and Minerals in Loblolly Pine Plantation on Four Arkansas Soils

Average contents of N, P, K, Ca, and Na and total above ground dry matter were determined in 19-year-old unthinned loblolly pine (Pinus taeda L.) plantations in southeastern Arkansas. Three stands were sampled on each of four sites: well and poorly drained coastal plain soils and well and poorly drained loessial soils. Total dry weights, determined from 15 felled trees on each of the 12 plots, ranged from 127,000 kg/ha on poorly drained loessial soil to 173,300 kg/ha on poorly drained coastal plain soil. Ranking of sites, in descending order of production of dry matter, P, K, and Na was: coastal plain poorly drained, coastal plain well drained, loess well drained, and loess poorly drained. Quantity of Ca in stemwood and stembark was 36% higher on well than poorly drained soils; P was 30% higher on coastal plain than loess soils. Results permit calculation of nutrient drain in timber harvests. Bark in 19-year-old plantations contained 44, 44, 25, and 50% of total N, P, K, and Ca in the stems

The inexorable resistance of inertia determines the initial regime of drop coalescence

Drop coalescence is central to diverse processes involving dispersions of drops in industrial, engineering and scientific realms. During coalescence, two drops first touch and then merge as the liquid neck connecting them grows from initially microscopic scales to a size comparable to the drop diameters. The curvature of the interface is infinite at the point where the drops first make contact, and the flows that ensue as the two drops coalesce are intimately coupled to this singularity in the dynamics. Conventionally, this process has been thought to have just two dynamical regimes: a viscous and an inertial regime with a crossover region between them. We use experiments and simulations to reveal that a third regime, one that describes the initial dynamics of coalescence for all drop viscosities, has been missed. An argument based on force balance allows the construction of a new coalescence phase diagram

Aerodynamic test results of bicycle helmets in different configurations: Towards a responsive design

© IMechE 2019. Within the sport of cycling, aerodynamic efficiency is a fundamental criterion for equipment such as bicycle frames, wheels, clothing and helmets. Emerging technologies continually challenge the rules governing the sport as designers, engineers, sports scientists and athletes attempt to gain the edge on their competition. This study compares three-dimensional (3D) printed bicycle helmet prototypes with three commercially available helmets via aerodynamic testing in a wind tunnel. One 3D printed helmet featured a mechanical mechanism allowing two states of ventilation closure to be examined for aerodynamic efficiency, while the other featured electronically adjustable ventilation openings tested at five different states of ventilation closure. Data were collected using an anthropometrically accurate mannequin sitting atop a bicycle in a road-cycling position. The results found that the mechanically controlled prototype offered a 4.1% increase in overall drag experienced by the mannequin with ventilation in the open position compared to the closed position. The electronic prototype showed an increase in drag as ventilation openings increased through the five states, with an overall difference in drag of 3.7% between closed and the maximum opening. These experimental findings indicate that the responsive helmet prototypes can significantly affect the drag force on a cyclist between their closed and open positions and, when understood as being adaptable using sensors and automated controls, may provide new opportunities to modify athlete performance throughout varying stages of training and competition

The use and effectiveness of the eLib subject gateways: a preliminary investigation

Internet subject gateways were set up under the Electronic Libraries Programme (eLib) in order to address some of the problems of searching the Internet which have been identified by information professionals, i.e. locating relevant, good quality information. This preliminary study examines the extent to which academics in two universities use three eLib subject gateways (EEVL, OMNI and SOSIG). The results are generally encouraging for the eLib programme, but it is necessary for the gateways to be more effectively promoted. The study also found that academics do not have the same misgivings about the general search engines as the information professionals and seem to use them more readily than the gateways

Factors Influencing Consumer Likelihood of Purchasing a Flexible-Fuel or Hybrid Automobile

Developing fuels and vehicles that reduce our reliance on fossil fuels has become a priority due to the threat of global climate change and desire for reduced dependence on oil imports. Flexible-fuel vehicles that can run on ethanol/gasoline blends of up to 85% ethanol and hybrid electric vehicles present two such opportunities. While production of both flexible-fuel and hybrid vehicles is increasing, there is still a great deal of uncertainty about how consumers will respond to these products. To address this uncertainty, data was collected through an online survey of automobile owners that asked respondents how likely they were to choose either a flexible-fuel or hybrid vehicle as their next vehicle. A bivariate probit model was used to jointly analyze responses to these two questions. The results show that, while there was some overlap in the factors correlated with perceived likelihood of choosing one of these two types of automobiles, there were also clear differences. These results should benefit policymakers, marketers and academics seeking a better understanding of the respective markets for these vehicles.flexible-fuel vehicles, ethanol, E85, hybrid electric vehicles, Demand and Price Analysis, Environmental Economics and Policy, Resource /Energy Economics and Policy,

EFFECTS OF RISK ON OPTIMAL NITROGEN FERTILIZATION DATES IN WINTER WHEAT PRODUCTION AS AFFECTED BY DISEASE AND NITROGEN SOURCE

Optimal fertilization dates were found for two nitrogen sources in the presence of two diseases for wheat farmers with different risk preferences. Risk was independent of fertilization date. Ammonium Nitrate and Urea-Ammonium Nitrate did not affect risk differently. Ammonium Nitrate applied on March 9 was optimal regardless of risk preferences.Crop Production/Industries,

EFFECTS OF RISK, DISEASE, AND NITROGEN SOURCE ON OPTIMAL NITROGEN FERTILIZATION RATES IN WINTER WHEAT PRODUCTION

Interactions among nitrogen (N) fertilization rate, N source, and disease severity can affect mean yield and yield variance in conservation tillage wheat production. A Just-Pope model was used to evaluate the effects of N rate, N source, and disease on the spring N-fertilization decision. Ammonium nitrate (AN) was the utility-maximizing N source regardless of risk preferences. The net-return-maximizing AN rate was 92 lb N/acre, providing $0.52/acre higher net returns than the best alternative N source (urea). If a farmer could anticipate a higher than average Take-All infection, the difference in optimal net-returns between AN and urea would increase to$35.11/acre.Crop Production/Industries,

Socioeconomic and Psychosocial Adversities Experienced by Creative Freelancers in the UK During the COVID-19 Pandemic: A Qualitative Study

There are concerns that the socioeconomic consequences of COVID-19, including unemployment and financial insecurity, are having adverse effects on the mental wellbeing of the population. One group particularly vulnerable to socioeconomic adversity during this period are those employed freelance within the cultural industry. Many workers in the sector were already subject to income instability, erratic work schedules and a lack of economic security before the pandemic, and it is possible that COVID-19 may exacerbate pre-existing economic precarity. Through interviews with 20 freelancers working within the performing arts, visual arts, and film and television industries, this article explores the impact of the pandemic on their working lives. Findings suggest the pandemic is affecting the psychological wellbeing of freelancers through employment loss, financial instability and work dissonance, and illustrates the need for urgent economic and psychosocial support for those employed within the cultural sector

Quadrilateral-octagon coordinates for almost normal surfaces

Normal and almost normal surfaces are essential tools for algorithmic 3-manifold topology, but to use them requires exponentially slow enumeration algorithms in a high-dimensional vector space. The quadrilateral coordinates of Tollefson alleviate this problem considerably for normal surfaces, by reducing the dimension of this vector space from 7n to 3n (where n is the complexity of the underlying triangulation). Here we develop an analogous theory for octagonal almost normal surfaces, using quadrilateral and octagon coordinates to reduce this dimension from 10n to 6n. As an application, we show that quadrilateral-octagon coordinates can be used exclusively in the streamlined 3-sphere recognition algorithm of Jaco, Rubinstein and Thompson, reducing experimental running times by factors of thousands. We also introduce joint coordinates, a system with only 3n dimensions for octagonal almost normal surfaces that has appealing geometric properties.Comment: 34 pages, 20 figures; v2: Simplified the proof of Theorem 4.5 using cohomology, plus other minor changes; v3: Minor housekeepin

A qualitative study exploring the impact of the COVID-19 pandemic on People Who Inject Drugs (PWID) and drug service provision in the UK: PWID and service provider perspectives

Background: People Who Inject Drugs (PWID) are subject to distinct socio-structural inequalities that can expose them to high risks of COVID –19 transmission and related health and social complications. In response to COVID –19 mitigation strategies, these vulnerabilities are being experienced in the context of adapted drug treatment service provision, including reduced in–person support and increased regulatory flexibility in opioid substitution therapy (OST) guidelines. This study aimed to explore the longer–term impact of the pandemic on the health and wellbeing of PWID, including provider and client experiences of treatment changes. / Methods: Interviews were conducted with 19 PWID and 17 drug treatment providers between May – September 2021, recruited from third –sector drug services in the UK. Data were analysed using reflexive thematic analysis. / Results: Most participants expressed ongoing fears of COVID –19 transmission, although socio-structural inequalities limited the contexts in which physical distancing could be practised. In addition, virus mitigation strategies altered the risk environment for PWID, resulting in ongoing physical (e.g. drug use patterns and characteristics), economic (e.g. sex work engagement and income generation) and social (e.g. stigmatization and marginalization) harms. Finally, whilst clients reported favourable experiences from service adaptations prompted by COVID –19, there was continued scepticism and caution among providers toward sustaining any treatment changes beyond the pandemic period. / Conclusions: Whilst our findings emphasize the importance of accessible support measures attending to the immediate priorities of PWID during this period, there is a need for additional supports to ensure socio–structural vulnerabilities that disproportionality affect PWID are not exacerbated by the pandemic. In addition, treatment adaptations initiated in response to the pandemic require further attention to ensure they are acceptable to both clients and providers