Evaluation of broiler house environmental management systems in East Tennessee : a case study

An air quality study was conducted for two different types of broiler house environmental management styles: naturally ventilated, and mechanically ventilated. A continuous sampling, stand alone, monitoring system was used to monitor four gases within the houses. These gases were Ammonia, Carbon Monoxide, Hydrogen Sulfide and Oxygen. Data points were logged every thirty minutes. Dust samples were also collected using universal flow sampling pumps and cartridge-type filters. Other data collected but not analyzed in this study were interior temperature and relative humidity and exterior temperature, relative humidity, and solar radiation. Statistical analyses were performed to test for differences in gas levels between environmental management styles. These tests revealed that a significant difference (p\u3c0.5) existed between management systems for maximum oxygen, maximum ammonia, and maximum hydrogen sulfide levels. Significant differences (p\u3c0.5) between farms with the same environmental management style were found for ammonia and carbon monoxide levels. These differences were attributed to the occurrence of an in house flood at Farm B2 (mechanically ventilated) and poor conditions observed at Farm D (naturally ventilated). A significant difference (p\u3c0.5) between weeks for maximum and average CO level was also found. This difference was attributed to the intense use of propane brooders during the early stages of production. Mean total dust concentrations ranged from 0.0010 to 0.0056 mg/L. Differences in dust concentration appeared to be a factor of exterior temperature and ventilation rate. Warmer exterior temperatures allowed for increased ventilation and dust concentrations were reduced. Conclusive results determining the overall effectiveness of either environmental management system (natural or mechanical) could not be formulated because of the significant differences (p\u3c0.5) that were found within farms with the same management system. This study concluded that the effectiveness of the management system was controlled by the producer and not the system itself

Second Intermediate Host-Specificity of \u3ci\u3eHaematoloechus complexus\u3c/i\u3e and \u3ci\u3eHaematoloechus medioplexus\u3c/i\u3e (Digenea: Haematoloechidae)

Second intermediate host-specificity was examined for two species of the frog lung fluke genus Haematoloechus. Nine species of freshwater arthropods were exposed to cercariae of H. complexus and H. medioplexus. Metacercariae of H. complexus developed in all arthropod species used. Metacercariae of H. medioplexus developed only in anisopteran odonate naiads. This difference in host utilization may have epizootiological implications. The potential development of H. complexus in a greater number of arthropods than H. medioplexus may increase the chances of ingestion of H. complexus by an anuran host. The range of arthropods parasitized by H. complexus indicates that host-specificity of the metacercarial stage of this fluke is not restricted by the phylogeny of aquatic arthropods

Introduction to Special Issue of \u3ci\u3eJournal of Defense Modeling and Simulation\u3c/i\u3e: Novel Approaches to Defense and Military Modeling and Simulation

Developing solutions to complex problems in government and industry is a daunting task that often requires tremendous investment in time and resources to solve. Modeling and simulation (M&S) has incredible potential to streamline development and cut costs by conducting virtual experiments that give insight into performance under various test conditions. As many program managers in the federal acquisition process can attest, realistic testing of live equipment in an operational environment can be some of the most expensive parts of a development program. M&S can provide insight into mission success of yetto- bedesigned systems without the need to actually build and test the system in the real world. Similarly, M&S tools can evaluate human effectiveness under various scenarios while only risking the virtual lives of avatars. When properly applied, M&S capabilities provide critical insight that allows leaders to make smart decisions about how to accomplish the mission and increase human performance more quickly and at lower cost and risk than reliance on real-world testing. Throughout this special issue, we examine a variety of novel M&S concepts that promise to deliver simulation results to the defense and military community that positively impact system-level mission studies and human effectiveness research. These M&S tools not only affect the defense and military community, but can also have application to a wide variety of government and industry users with needs to solve similar problem sets. Whether the end goal is cost savings, operational analysis or refinement of sub-components, the M&S concepts described in this special issue testify to the power that these tools can provide to help decision makers efficiently allocate scarce resources and provide improved performance of humans and the systems that they operate in the long run

Role of The Cortex in Visuomotor Control of Arm Stability

Whereas numerous motor control theories describe the control of arm trajectory during reach, the control of stabilization in a constant arm position (i.e., visuomotor control of arm posture) is less clear. Three potential mechanisms have been proposed for visuomotor control of arm posture: 1) increased impedance of the arm through co-contraction of antagonistic muscles, 2) corrective muscle activity via spinal/supraspinal reflex circuits, and/or 3) intermittent voluntary corrections to errors in position. We examined the cortical mechanisms of visuomotor control of arm posture and tested the hypothesis that cortical error networks contribute to arm stabilization. We collected electroencephalography (EEG) data from 10 young healthy participants across four experimental planar movement tasks. We examined brain activity associated with intermittent voluntary corrections of position error and antagonist co-contraction during stabilization. EEG beta-band (13–26 Hz) power fluctuations were used as indicators of brain activity, and coherence between EEG electrodes was used as a measure of functional connectivity between brain regions. Cortical activity in the sensory, motor, and visual areas during arm stabilization was similar to activity during volitional arm movements and was larger than activity during co-contraction of the arm. However, cortical connectivity between the sensorimotor and visual regions was higher during arm stabilization compared with volitional arm movements and co-contraction of the arm. The difference in cortical activity and connectivity between tasks might be attributed to an underlying visuomotor error network used to update motor commands for visuomotor control of arm posture

Redescription of the Frog Bladder Fluke \u3ci\u3eGorgoderina attenuata\u3c/i\u3e from the Northern Leopard Frog, \u3ci\u3eRana pipiens\u3c/i\u3e

Morphological characters used to differentiate North American bladder flukes, Gorgoderina spp., are problematic and different authors use different morphological characteristics for distinguishing species. More importantly, no type specimens exist for four of the 12 North American species infecting anuran and caudatan hosts. A redescription of Gorgoderina attenuata (Stafford, 1902) Stafford, 1905 is based on new collections from 6 species of anurans from Arkansas, Nebraska, New York, and Wisconsin. Morphological comparisons between gravid G. attenuata recovered from bullfrogs and northern leopard frogs indicated statistically significant differences in 11 of 28 morphological characters examined. However, there was overlap among all of these characters, and it is unclear whether these morphological types represent host-induced morphological changes in worm morphology or cryptic species. Based on our findings, we suggest that morphological and molecular data from G. attenuata-like worms recovered from the other 23 definitive hosts reported for G. attenuata need to be collected to resolve this issue

Evolutionary Constraints on Population Structure: The Parasites of \u3ci\u3eFundulus zebrinus\u3c/i\u3e (Pisces: Cyprinodontidae) in the South Platte River of Nebraska

Population and community descriptor values (parasites per host, prevalence per parasite species, variance/mean ratios, species density, and diversity indices) for the 7-species parasite community of 61 relatively homogeneous samples of Fundulus zebrinus (Pisces: Cyprinodontidae) in the South Platte River of Nebraska, U.S.A., taken over a 14-yr period, are reported. South Platte River streamflow fluctuates over two orders of magnitude on several time scales-monthly, annually, and over multiple year wet-dry cycles. Relatively homogeneous sampling of a single host species with several parasite species provided a system that allowed assessment of the contribution of evolved parasite life cycles to population structure in an everchanging environment. No significant negative species-to-species associations were observed. Species abundance, order of abundance, and diversity were affected most strongly by streamflow, with high water reducing prevalence and abundance of larval trematode parasites. Each parasite species had its characteristic long- and short-term patterns of variation in population descriptor values, with mostly long- term stability superimposed on sometimes extreme short-term fluctuations of descriptor values. The differences in these characteristic patterns were considered products primarily of the evolved life cycle traits and transmission mechanisms operating in the common fluctuating environment. The parasite community as a whole showed resilience, returning to preperturbation diversity following extended periods of high water

Evolutionary Constraints on Population Structure: The Parasites of \u3ci\u3eFundulus zebrinus\u3c/i\u3e (Pisces: Cyprinodontidae) in the South Platte River of Nebraska

Population and community descriptor values (parasites per host, prevalence per parasite species, variance/mean ratios, species density, and diversity indices) for the 7-species parasite community of 61 relatively homogeneous samples of Fundulus zebrinus (Pisces: Cyprinodontidae) in the South Platte River of Nebraska, U.S.A., taken over a 14-yr period, are reported. South Platte River streamflow fluctuates over two orders of magnitude on several time scales-monthly, annually, and over multiple year wet-dry cycles. Relatively homogeneous sampling of a single host species with several parasite species provided a system that allowed assessment of the contribution of evolved parasite life cycles to population structure in an everchanging environment. No significant negative species-to-species associations were observed. Species abundance, order of abundance, and diversity were affected most strongly by streamflow, with high water reducing prevalence and abundance of larval trematode parasites. Each parasite species had its characteristic long- and short-term patterns of variation in population descriptor values, with mostly long- term stability superimposed on sometimes extreme short-term fluctuations of descriptor values. The differences in these characteristic patterns were considered products primarily of the evolved life cycle traits and transmission mechanisms operating in the common fluctuating environment. The parasite community as a whole showed resilience, returning to preperturbation diversity following extended periods of high water

Evolutionary Constraints on Population Structure: The Parasites of \u3ci\u3eFundulus zebrinus\u3c/i\u3e (Pisces: Cyprinodontidae) in the South Platte River of Nebraska

Population and community descriptor values (parasites per host, prevalence per parasite species, variance/mean ratios, species density, and diversity indices) for the 7-species parasite community of 61 relatively homogeneous samples of Fundulus zebrinus (Pisces: Cyprinodontidae) in the South Platte River of Nebraska, U.S.A., taken over a 14-yr period, are reported. South Platte River streamflow fluctuates over two orders of magnitude on several time scales-monthly, annually, and over multiple year wet-dry cycles. Relatively homogeneous sampling of a single host species with several parasite species provided a system that allowed assessment of the contribution of evolved parasite life cycles to population structure in an everchanging environment. No significant negative species-to-species associations were observed. Species abundance, order of abundance, and diversity were affected most strongly by streamflow, with high water reducing prevalence and abundance of larval trematode parasites. Each parasite species had its characteristic long- and short-term patterns of variation in population descriptor values, with mostly long- term stability superimposed on sometimes extreme short-term fluctuations of descriptor values. The differences in these characteristic patterns were considered products primarily of the evolved life cycle traits and transmission mechanisms operating in the common fluctuating environment. The parasite community as a whole showed resilience, returning to preperturbation diversity following extended periods of high water

Evolutionary Constraints on Population Structure: The Parasites of \u3ci\u3eFundulus zebrinus\u3c/i\u3e (Pisces: Cyprinodontidae) in the South Platte River of Nebraska

Population and community descriptor values (parasites per host, prevalence per parasite species, variance/mean ratios, species density, and diversity indices) for the 7-species parasite community of 61 relatively homogeneous samples of Fundulus zebrinus (Pisces: Cyprinodontidae) in the South Platte River of Nebraska, U.S.A., taken over a 14-yr period, are reported. South Platte River streamflow fluctuates over two orders of magnitude on several time scales-monthly, annually, and over multiple year wet-dry cycles. Relatively homogeneous sampling of a single host species with several parasite species provided a system that allowed assessment of the contribution of evolved parasite life cycles to population structure in an everchanging environment. No significant negative species-to-species associations were observed. Species abundance, order of abundance, and diversity were affected most strongly by streamflow, with high water reducing prevalence and abundance of larval trematode parasites. Each parasite species had its characteristic long- and short-term patterns of variation in population descriptor values, with mostly long- term stability superimposed on sometimes extreme short-term fluctuations of descriptor values. The differences in these characteristic patterns were considered products primarily of the evolved life cycle traits and transmission mechanisms operating in the common fluctuating environment. The parasite community as a whole showed resilience, returning to preperturbation diversity following extended periods of high water