The Feasibility of a Cooperatively Owned Large-Scale Hog Farrowing System in North Dakota

Interest in the feasibility of a cooperatively owned large-scale hog farrowing system has been shown by hog producers in North Dakota. The producers realize the problems in securing a continuous supply of disease free feeder pigs of uniform quality during fluctuating price periods. Lack of published data concerning large-scale farrowing systems makes decisions regarding the feasibility and negotiation with lending institutions difficult. The research for this report was conducted under North Dakota Agricultural Experiment Station Projects 1350 and 3337. The research was supported in part by grants from the Business and Industrial Development Department and the Economic Development Administration (Grant Project Number 05-6-01402). Special assistance in conducting the study and preparing the report was provided through the Research and Extension Rural Development Project at North Dakota State University.Agribusiness, Production Economics,

Identification of a non-mammalian leptin-like gene:characterization and expression in the tiger salamander (Ambystoma tigrinum)

Leptin is well established as a multifunctional cytokine in mammals. However, little is known about the evolution of the leptin gene in other vertebrates. A recently published set of ESTs from the tiger salamander (Ambystoma tigrinum) contains a sequence sharing 56% nucleotide sequence identity with the human leptin cDNA. To confirm that the EST is naturally expressed in the salamander, a 409 bp cDNA was amplified by RT-PCR of salamander testis and stomach mRNAs. The coding sequence of the cDNA is predicted to encode 169 amino acids, and the mature peptide to consist of 146 residues, as in mammals. Although the overall amino acid identity with mammalian leptins is only 29%, the salamander and mammalian peptides share common structural features. An intron was identified between coding exons providing evidence that the sequence is present in the salamander genome. Phylogenetic analysis showed a rate of molecular divergence consistent with the accepted view of vertebrate evolution. The pattern of tissue expression of the leptin-like cDNA differed between metamorphosed adult individuals of different sizes suggesting possible developmental regulation. Expression was most prominent in the skin and testis, but was also detected in tissues in which leptin mRNA is present in mammals, including the fat body, stomach, and muscle. The characterization of a salamander leptin-like gene provides a basis for understanding how the structure and functions of leptin have altered during the evolution of tetrapod vertebrates

Determinants of Cognitive Offloading: Toward a Metacognitive Approach

Individuals frequently make use of the body and environment when engaged in a cognitive task. For example, individuals will often spontaneously physically rotate when faced with rotated objects, such as an array of words, putatively to offload the costs associated with stimulus rotation. We examined this idea further by independently manipulating the costs associated with both word rotation and array frame rotation. Surprisingly, we found that individuals’ patterns of spontaneous physical rotations did not follow patterns of rotation costs or benefits associated with being physically rotated, findings difficult to reconcile with existing theories of strategy selection involving external resources. Individuals’ subjective ratings of perceived benefits, rather, provided an excellent match to the patterns of physical rotations, suggesting that theory-based metacognitive judgments are used when deciding on-the-fly whether to incorporate an external resource such as the body. Implications for metacognition’s future in theories of cognitive offloading are discussed.1 yea

On the Determinants of Effort

That humans configure their behaviors in ways to avoid effortful actions is undoubtedly one of the most pervasive hypotheses put forth to account for a wide range of human behaviors. This dissertation describes a series of experiments aimed at testing accounts of how individuals make effort-based decisions, and why actions may be evaluated as effortful. In Chapter 1, I contrasted the hypothesis that individuals’ effort avoidance behaviors and conceptions of effort are driven by the performance associated with different lines of actions, versus the hypothesis that individuals generate a kind of metacognitive evaluation of effort that can be dissociated from performance. I found that individuals’ choices were not associated with their performance or with a physiological measure of demand, but rather tracked closely with subjective perceptions of effort associated with embedded cues supporting the latter hypothesis. Chapter 2 extended the idea that individuals make their effort-based decisions by utilizing cues through pitting options against one another that vary on cue saliency, demands on executive control, and performance. Chapter 3 looked to test how individuals evaluate expected effort across a range of tasks through manipulations of evaluation mode (i.e., whether options are evaluated comparatively or in isolation). Following from these results, I propose that evaluable forms of effort are driven by the presence of a failure point associated with the task. In Chapter 4, specific determinants of effort were examined by crossing anticipated time demands and error likelihood across different choice options. Data supported the notion that judgments of effort are closely related to the perceived likelihood of an error associated with a task, but not to the time demands. I conclude by proposing that cognitive effort can best be conceived of as a type of inferential metacognitive evaluation made over available cues that are weighed on the perceived likelihood of making errors

Criminal Law and Procedure

This Article surveys recent developments in criminal procedure and law in Virginia. Because of space limitations, the authors have limited their discussion to the most significant published appellate decisions and legislation

Method for monitoring GaAs photocathode heat cleaning temperature

Before a GaAs photocathode can be activated to achieve a negative electron affinity condition, the GaAs crystal must be cleaned. This is most commonly done by ohmic, radiative, or electron bombardment heating. We report a new technique to monitor the temperature of heated GaAs photocathodes by observation with a camera. The method is robust and yields the same temperatures for different GaAs samples heated using different methods in different mounting configurations

Spinal Projection Neurons Control Turning Behaviors in Zebrafish

SummaryDiscrete populations of brainstem spinal projection neurons (SPNs) have been shown to exhibit behavior-specific responses during locomotion [1–9], suggesting that separate descending pathways, each dedicated to a specific behavior, control locomotion. In an alternative model, a large variety of motor outputs could be generated from different combinations of a small number of basic motor pathways. We examined this possibility by studying the precise role of ventromedially located hindbrain SPNs (vSPNs) in generating turning behaviors. We found that unilateral laser ablation of vSPNs reduces the tail deflection and cycle period specifically during the first undulation cycle of a swim bout, whereas later tail movements are unaffected. This holds true during phototaxic [10], optomotor [11], dark-flash-induced [12], and spontaneous turns [13], suggesting a universal role of these neurons in controlling turning behaviors. Importantly, we found that the ablation not only abolishes turns but also results in a dramatic increase in the number of forward swims, suggesting that these neurons transform forward swims into turns by introducing turning kinematics into a basic motor pattern of symmetric tail undulations. Finally, we show that vSPN activity is direction specific and graded by turning angle. Together, these results provide a clear example of how a specific motor pattern can be transformed into different behavioral events by the graded activation of a small set of SPNs

Measurements and Modeling of Transient Blood Flow Perturbations Induced by Brief Somatosensory Stimulation

Proper interpretation of BOLD fMRI and other common functional imaging methods requires an understanding of neurovascular coupling. We used laser speckle-contrast optical imaging to measure blood-flow responses in rat somatosensory cortex elicited by brief (2 s) forepaw stimulation. Results show a large increase in local blood flow speed followed by an undershoot and possible late-time oscillations. The blood flow measurements were modeled using the impulse response of a simple linear network, a four-element windkessel. This model yielded excellent fits to the detailed time courses of activated regions. The four-element windkessel model thus provides a simple explanation and interpretation of the transient blood-flow response, both its initial peak and its late-time behavior