2,601 research outputs found
False Starts, Suspicious Interviewees and Nearly Impossible Tasks: Some Reflections on the Difficulty of Conducting Field Research Abroad
In this article, I discuss some of the problems I have encountered in conducting field research abroad, specifically in England, South Africa, Russia and China - a broad variety of societies ranging from free to not free societies. I discuss the problems I encountered and how I overcame some of them and was stymied by others. I have had problems gaining access to interviewees; establishing rapport with interviewees from different societies; and have had my motives questioned. Nevertheless, my research has been rewarding and has resulted in a number of serendipitous discoveries
Production Systems Involving Stocker Cattle and Soft Red Winter Wheat
A three year study at the Livestock and Forestry Research Station near Batesville, Arkansas evaluated production systems involving stocker cattle and soft red winter wheat. Grazing of soft red winter wheat forage from October through February followed by harvesting wheat grain or grazing through April with stocker cattle offers an alternative to conventional farming. Soft red winter wheat, when planted by September 15, produces an ample supply of high-quality forage that supports rapid growth of stocker cattle during October through April. Net income from stocker cattle averaged over 75,000,000 per year if 750,000 acres of wheat are grazed
Lunar base CELSS: A bioregenerative approach
During the twenty-first century, human habitation of a self-sustaining lunar base could become a reality. To achieve this goal, the occupants will have to have food, water, and an adequate atmosphere within a carefully designed environment. Advanced technology will be employed to support terrestrial life-sustaining processes on the Moon. One approach to a life support system based on food production, waste management and utilization, and product synthesis is outlined. Inputs include an atmosphere, water, plants, biodegradable substrates, and manufacutured materials such as fiberglass containment vessels from lunar resources. Outputs include purification of air and water, food, and hydrogen (H2) generated from methane (CH4). Important criteria are as follows: (1) minimize resupply from Earth; and (2) recycle as efficiently as possible
Tension Pneumocephalus Related to Spontaneous Skull Base Dehiscence in a Patient on BiPAP
Spontaneous pneumocephalus is an uncommon phenomenon that may develop in patients with occult skull base defects. There have been reports of pneumocephalus occurring spontaneously in the setting of continuous positive airway pressure (CPAP) use (1). Tension pneumocephalus represents a neurosurgical emergency where intracranial air is trapped with increasing pressures resulting in neurological deterioration (2). Previous literature has also documented the growing understanding of how obesity, elevated intracranial pressure (ICP), obstructive sleep apnea (OSA), and cortical skull thinning are associated with spontaneous tegmen dehiscence and cerebrospinal fluid (CSF) leakage (3). Other mechanisms for spontaneous CSF leak include aberrant arachnoid granulation, congenital skull base dehiscences, increased abdominal and thoracic pressure resulting in reduced cerebral venous drainage, and age-related cortical thinning. In this report, we present the case of a bilevel positive airway pressure (BiPAP) user with an undiagnosed spontaneous tegmen dehiscence who developed spontaneous tension pneumocephalus
Ecological equivalence: a realistic assumption for niche theory as a testable alternative to neutral theory
Hubbell's 2001 neutral theory unifies biodiversity and biogeography by modelling steady-state distributions of species richness and abundances across spatio-temporal scales. Accurate predictions have issued from its core premise that all species have identical vital rates. Yet no ecologist believes that species are identical in reality. Here I explain this paradox in terms of the ecological equivalence that species must achieve at their coexistence equilibrium, defined by zero net fitness for all regardless of intrinsic differences between them. I show that the distinction of realised from intrinsic vital rates is crucial to evaluating community resilience. An analysis of competitive interactions reveals how zero-sum patterns of abundance emerge for species with contrasting life-history traits as for identical species. I develop a stochastic model to simulate community assembly from a random drift of invasions sustaining the dynamics of recruitment following deaths and extinctions. Species are allocated identical intrinsic vital rates for neutral dynamics, or random intrinsic vital rates and competitive abilities for niche dynamics either on a continuous scale or between dominant-fugitive extremes. Resulting communities have steady-state distributions of the same type for more or less extremely differentiated species as for identical species. All produce negatively skewed log-normal distributions of species abundance, zero-sum relationships of total abundance to area, and Arrhenius relationships of species to area. Intrinsically identical species nevertheless support fewer total individuals, because their densities impact as strongly on each other as on themselves. Truly neutral communities have measurably lower abundance/area and higher species/abundance ratios. Neutral scenarios can be parameterized as null hypotheses for testing competitive release, which is a sure signal of niche dynamics. Ignoring the true strength of interactions between and within species risks a substantial misrepresentation of community resilience to habitat los
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