Cattle Temporal and Spatial Distribution in Midwestern Pastures Using Global Positioning (Three-year Progress Report)

Previous research has shown that grazing cattle tend to congregate in streamside zones of pastures to obtain water and shade for thermoregulation. However, problems associated with thermoregulation may be increased because of the presence of endophyte-infected tall fescue in pastures. Defining relationships between cattle distribution, such pasture characteristics as size, shape, shade distribution, botanical composition, and climatic factors related to heat stress, will provide the basis for the development and implementation of management practices that minimize nonpoint source pollution possibly associated with grazing cattle

Cattle Temporal & Spatial Distribution in Midwestern Pastures Using Global Positioning (A Three-Year Progress Report)

Eight pastures on five southern Iowa cow-calf farms were used to evaluate the effects of pasture characteristics and microclimatic conditions on cattle grazing cool-season grass pastures with streams and/or ponds. Pastures ranged from 19 to 309 acres and contained varying proportions of cool-season grasses, legumes, sedge, broadleaf weeds, brush, and bare ground. The percentages of pasture area that were shaded ranged from 19 to 73%. Cows were Angus and Angus-Cross on seven of the pastures, and Mexican Corriente on the remaining pasture. In spring, summer, and fall of 2007, 2008, and 2009, 2 to 3 cows per pasture were fitted with Global Positioning System (GPS) collars to record position at 10 minute intervals for periods of 5 to 14 days. Ambient temperature, black globe temperature, dew point, relative humidity, and wind speed and direction were collected with HOBO data loggers at ten minute intervals over the 2007, 2008, and 2009 grazing seasons on each farm. Streams, ponds, and fence lines were referenced on a geospatial map and used to establish zones in the pastures. Designated zones were: in the stream or pond, within 100 feet, or greater than 100 ft (uplands) from the stream or pond (water source). One hundred thirty-nine data sets were obtained throughout the three-year project. Mean proportions of observations when cattle were in the water source differed (P\u3c0.0001) between farms, but not between seasons (P=0.5824). Mean proportions of time cattle spent within 100, or greater 100 ft of the water source differed (P\u3c0.0001) among farms. The proportion of time cattle were within the streamside zone (defined as being in the water source or within 100 feet of the water source) increased with increasing ambient temperature, increasing the proportion of streamside zone within a pasture, increasing the proportion of total pasture shade within the streamside zone, and decreasing pasture size. Therefore, implementation of grazing management practices for the protection of pasture streams are more likely to be effective on small and/or narrow pastures in which cattle have less opportunity to locate in upland locations

Consistency and Variation in Spatial Reference

Modeling the meaning and use of linguistic expressions describing spatial relationships holding between a target object and a landmark object requires an understanding of both the consistency and variation in human performance in this area. Previous research [Herskovits 1985] attempts to account for some of this variation in terms of the angular deviation holding among objects in thevisual display. This approach is shown to fail to account for the full range of human variation inperformance, and a specific alternative algorithm is offered which is grounded in task variability and the notions of corridor and centroid. The significance to this algorithm of task variation, of theseparation of semantic from pragmatic issues, and of the role of function and structure is discusse

Opioids depress cortical centers responsible for the volitional control of respiration

Respiratory depression limits provision of safe opioid analgesia and is the main cause of death in drug addicts. Although opioids are known to inhibit brainstem respiratory activity, their effects on cortical areas that mediate respiration are less well understood. Here, functional magnetic resonance imaging was used to examine how brainstem and cortical activity related to a short breath hold is modulated by the opioid remifentanil. We hypothesized that remifentanil would differentially depress brain areas that mediate sensory-affective components of respiration over those that mediate volitional motor control. Quantitative measures of cerebral blood flow were used to control for hypercapnia-induced changes in blood oxygen level-dependent (BOLD) signal. Awareness of respiration, reflected by an urge-to-breathe score, was profoundly reduced with remifentanil. Urge to breathe was associated with activity in the bilateral insula, frontal operculum, and secondary somatosensory cortex. Localized remifentanil-induced decreases in breath hold-related activity were observed in the left anterior insula and operculum. We also observed remifentanil-induced decreases in the BOLD response to breath holding in the left dorsolateral prefrontal cortex, anterior cingulate, the cerebellum, and periaqueductal gray, brain areas that mediate task performance. Activity in areas mediating motor control (putamen, motor cortex) and sensory-motor integration (supramarginal gyrus) were unaffected by remifentanil. Breath hold-related activity was observed in the medulla. These findings highlight the importance of higher cortical centers in providing contextual awareness of respiration that leads to appropriate modulation of respiratory control. Opioids have profound effects on the cortical centers that control breathing, which potentiates their actions in the brainstem

Direct characterisation of tuneable few-femtosecond dispersive-wave pulses in the deep UV

Dispersive wave emission (DWE) in gas-filled hollow-core dielectric waveguides is a promising source of tuneable coherent and broadband radiation, but so far the generation of few-femtosecond pulses using this technique has not been demonstrated. Using in-vacuum frequency-resolved optical gating, we directly characterise tuneable 3fs pulses in the deep ultraviolet generated via DWE. Through numerical simulations, we identify that the use of a pressure gradient in the waveguide is critical for the generation of short pulses.Comment: 5 pages, 4 figure