5 results
Management in a modified no-tillage corn–soybean–wheat rotation influences weed population and community dynamics
- Clarence J. Swanton, Barbara D. Booth, Kevin Chandler, David R. Clements, Anil Shrestha
-
- Journal:
- Weed Science / Volume 54 / Issue 1 / February 2006
- Published online by Cambridge University Press:
- 20 January 2017, pp. 47-58
-
- Article
- Export citation
-
Conservation tillage systems, such as no-tillage, are ecologically advantageous because they reduce soil erosion; however, they rely heavily on herbicide use. Our goal was to determine how weed communities of no-tillage systems are affected when the system is modified to reduce herbicide use through a combination of banded herbicides and interrow cultivation. To this end, we conducted a 9-yr study in a no-tillage corn–soybean–winter wheat rotation. All management systems had a preplant application of glyphosate, followed by either broadcast PRE herbicides (conventional no-tillage), interrow cultivation with banded PRE herbicides, or interrow cultivation alone. Aboveground weed densities were assessed each year and data were grouped into early (1991 to 1993) and late (1996 to 1998) time periods. Over time, weed communities became more distinct, showing a strong response to management and crop. In the early years, weed communities separated more in response to management than crop. In the late years, this was reversed. Weed communities in systems with interrow cultivation were more diverse than those in conventional no-tillage. The response to weed management system and crop was species specific. For example, the abundance of yellow foxtail was higher when interrow cultivation was employed, but abundance was equal in all crops. Dandelion was more abundant in conventional no-tillage of corn and soybean; however, it was equally abundant in all management systems in wheat. Seed bank species richness increased over time and was highest in systems with interrow cultivation. Herbicide use can be reduced in a modified no-tillage corn–soybean–wheat rotation by incorporating interrow cultivation, with or without banded herbicides, into the management plan. The weed community trajectory changes, and the weed community becomes more diverse. A more diverse weed community will not necessarily alter how we manage weeds.
Evaluation of alternative weed management systems in a modified no-tillage corn–soybean–winter wheat rotation: weed densities, crop yield, and economics
- Clarence J. Swanton, Anil Shrestha, David R. Clements, Barbara D. Booth, Kevin Chandler
-
- Journal:
- Weed Science / Volume 50 / Issue 4 / August 2002
- Published online by Cambridge University Press:
- 20 January 2017, pp. 504-511
-
- Article
- Export citation
-
A 9-yr (1990–1998) study was conducted at Woodstock, ON, Canada, to evaluate weed densities, crop yields, and gross returns in a modified no-tillage (no primary tillage) corn–soybean–winter wheat rotation under three weed management treatments: (1) minimum, preplant application of glyphosate followed by mechanical control; (2) integrated weed management (IWM), preplant application of glyphosate followed by band application of preemergence herbicides plus mechanical control; and (3) conventional, preplant application of glyphosate followed by broadcast application of preemergence herbicides in corn and soybean. In wheat the minimum and IWM treatments had no additional weed control measures other than the preplant application of glyphosate, whereas the conventional treatment had a broadcast application of a postemergence herbicide. Weed densities were assessed each year, (except in 1990) once during the growing season in corn and soybean and immediately after crop harvest in wheat. Adjusted gross return was calculated as the gross revenue minus the unique costs for weed control for each of the treatments. Weed densities were greater in the minimum treatment compared with the IWM or conventional treatment in all crops. Weed densities in the IWM and conventional treatments did not differ. There was no apparent “buildup” of weed density with time in the rotation resulting from weed escapes. Hence, these data challenge current thinking that weed densities increase with time if weed escapes are allowed to go to seed. Corn and soybean yields in the IWM and conventional treatments did not differ. However, the minimum treatment had the lowest corn and soybean yields. Winter wheat yield was not affected by the treatments. All weed management treatments provided similar gross returns for each crop and for the rotation. Thus, the minimum treatment consisting of glyphosate applied preplant followed by shallow interrow tillage appeared to be a viable option, especially if practiced in a farming system capable of ensuring adequate timing of cultivation operations.
Gallium-Induced Milling of Silicon: A Computational Investigation of Focused Ion Beams
- Michael F. Russo, Mostafa Maazouz, Lucille A. Giannuzzi, Clive Chandler, Mark Utlaut, Barbara J. Garrison
-
- Journal:
- Microscopy and Microanalysis / Volume 14 / Issue 4 / August 2008
- Published online by Cambridge University Press:
- 04 July 2008, pp. 315-320
- Print publication:
- August 2008
-
- Article
- Export citation
-
Molecular dynamics simulations are performed to model milling via a focused ion beam (FIB). The goal of this investigation is to examine the fundamental dynamics associated with the use of FIBs, as well as the phenomena that govern the early stages of trench formation during the milling process. Using a gallium beam to bombard a silicon surface, the extent of lateral damage (atomic displacement) caused by the beam at incident energies of both 2 and 30 keV is examined. These simulations indicate that the lateral damage is several times larger than the beam itself and that the mechanism responsible for the formation of a V-shaped trench is due to both the removal of surface material, and the lateral and horizontal migration of subsurface silicon atoms toward the vacuum/crater interface. The results presented here provide complementary information to experimental images of trenches created during milling with FIBs.
15 - Continence and stroke
-
- By Barbara J. Chandler, Hunters Moor Regional Neurorehabilitation Centre
- Edited by Michael P. Barnes, University of Newcastle upon Tyne, Bruce H. Dobkin, University of California, Los Angeles, Julien Bogousslavsky, Université de Lausanne, Switzerland
-
- Book:
- Recovery after Stroke
- Published online:
- 05 August 2016
- Print publication:
- 10 March 2005, pp 415-435
-
- Chapter
- Export citation
-
Summary
Introduction
In early childhood, the achievement of continence is a major goal and attracts great reward when it is successfully mastered. Following this, continence is forgotten – it is simply assumed to exist. The occurrence of incontinence in adult life is associated with shock, embarrassment, and often fear. It may have far-reaching effects on lifestyle. Patients have described becoming housebound because of fear of incontinence. Fecal incontinence may be even more distressing and have a profound effect upon rehabilitation and reintegration into social and family life. It has been termed the “unvoiced symptom” (Leigh and Turnberg, 1982). In a study amongst 115 patients with spinal cord injury, bowel dysfunction was considered to be one of the most distressing of their disabilities (Glickman and Kamm, 1996).
Daily urinary incontinence is not uncommon, affecting at least 1 in 20 of those under 65 years and increasing with age (Brittain, 1998). There may be a reticence about disclosing the problem even to a health professional. People may have too low an expectation of benefit from treatment and yet there is much that can be offered to alleviate symptoms (Yarnell et al., 1981; Jarvis, 1993).
Urinary incontinence
Urinary incontinence is defined as the involuntary leakage of urine that is a social or hygienic problem and is objectively demonstrable (Anon., 1990).
Prevalence
A survey by MORI involving interviews with 4000 people aged 30 years and over, in their own homes, revealed that 14% of women and 6.6% of men had experienced urinary incontinence. The definition of urinary incontinence used in the study was a positive reply to the question, “Have you suffered from bladder problems, for example leaking, wet pants, damp pants?” (Brocklehurst, 1993). Half of those with incontinence had seen their general practitioner. An earlier study involving a postal questionnaire sent to 22 430 people used a definition of regular urinary incontinence as “involuntary excretion or leakage of urine in inappropriate places or at inappropriate times twice or more a month.” This study revealed a prevalence of urinary incontinence of 8.5% in women and 1.6% in males aged 15–64 years. These figures rose to 11.6% of women and 6.9% of males aged 65 and over (Thomas et al., 1980).
16 - Sex and relationships following stroke
-
- By Barbara J. Chandler, Hunters Moor Regional Neurorehabilitation Centre
- Edited by Michael P. Barnes, University of Newcastle upon Tyne, Bruce H. Dobkin, University of California, Los Angeles, Julien Bogousslavsky, Université de Lausanne, Switzerland
-
- Book:
- Recovery after Stroke
- Published online:
- 05 August 2016
- Print publication:
- 10 March 2005, pp 436-455
-
- Chapter
- Export citation
-
Summary
Introduction
Sexuality and the ability to form and sustain an intimate relationship is a fundamental aspect of human life. It results from a complex interplay of physical, psychological, and emotional functioning within a social and cultural context. This chapter reviews the prevalence of sexual problems in the general population, the population with neurological disability, and those specifically with stroke. Sexual development and the physiology of sexual responsiveness are discussed followed by a discussion of relationship functioning. Finally, approaches to dealing with sex and relationship problems are discussed.
Prevalence of sexual dysfunction
In the general population
Dunn et al., (1998, 1999) carried out an anonymous postal questionnaire survey to examine the prevalence of sexual problems. From 4000 questionnaires, replies were received from 789 men and 979 women. The median age of the responders was 50 years, of whom 34% of the men and 41% of women reported a current sexual problem. The most common problems were erectile dysfunction and premature ejaculation in men and vaginal dryness and infrequent orgasm in women. Frequency of problems increased with age for men, but not women. Over half the responders reporting a sexual problem indicated they would like to receive professional help, but only 10% of these had received help.
Erectile dysfunction was most strongly associated with prostatic problems, but also with hypertension and diabetes mellitus. The most common associated factor with premature ejaculation was anxiety. In women, the most prominent association with arousal, orgasmic, and enjoyment problems was relationship difficulties, but anxiety and depression were also associated. The authors summarized that sexual problems clustered with self-reported physical problems in men whereas, in women, the association was with psychological and social problems.
A similar study in the USA amongst 1749 women and 1410 men, aged between 18 and 59 years, found sexual dysfunction amongst 43% of the female respondents and 31% of the male respondents. They described sexual dysfunction as being highly associated with negative experiences within sexual relationships and with overall well-being (Laumann et al., 1999).
In neurological disability
Detailed studies of sexual functioning among various groups with neurological disability have disclosed a high prevalence of sexual dysfunction. For example in multiple sclerosis, almost two-thirds of men and over one-third of women described unsatisfactory sex lives (Lilius et al., 1976).