Radio frequency field strength fluctuation due to digital conversion of television signals: a pilot study

2010 Summer.Includes bibliographic references (pages 47-54).Covers not scanned.Print version deaccessioned 2022.All television stations in the United States ceased broadcasting on analog airwaves June 12, 2009 and now only broadcast in a digital format. Prior to June 12th, most stations broadcast in both analog and digital signals. The focus of this study was to determine whether this change in broadcasting affected exposures to radio frequency energies in the vicinity of Lookout Mountain in Golden, Colorado. The site, which is approximately 10 miles west of the Denver metropolitan area, is unique because there are homes located at and above the elevation of the transmitting towers with some homes located within 100 yards of the towers. There is public concern that the digital transition resulted in a significant increase in radio frequency exposure to homes. Measurements of radio frequency field strengths were taken during daylight hours at 21 locations where highest exposures were expected using an electromagnetic radiation meter. Measurements taken at the same locations before and after June 12, 2009 did not indicate a statistically significant change in radio frequency exposures and all measurements were below the Maximum Permissible Exposure (MPE) limit for the general public

Homeostatic compensation and neuromodulation maintain synchronized motor neuron activity in the crustacean cardiac ganglion

Dissertation supervisor: Dr. David J. Schulz.Includes vita.Animals rely on the nervous system to produce appropriate behavior throughout their lives. In sending commands to the musculature for rhythmic motor behaviors such as breathing or walking, neural networks must be stable enough to send a reliable level of drive with the proper temporal coordination. Networks must also be flexible enough to meet changing environmental demands. A network's output ultimately arises from the intrinsic excitability of its constituent neurons and the synaptic connections between them. Interestingly, neurons and networks are able to produce highly conserved output from highly variable underlying intrinsic and synaptic properties. To explore the consequences of this variability, we have used the crustacean cardiac ganglion (CG) which consists of 9 neurons: 4 pacemaker cells that give excitatory input to 5 Large Cell motor neurons (LCs) which are responsible for driving the simultaneous contraction of the musculature that makes up the walls of the animal's single-chambered heart (Alexandrowicz, 1934; Hartline, 1967; Anderson and Cooke, 1971). The intact network can be dissected from the animal in physiological saline and it continues to produce robust, reliable, and rhythmic output (Welsh and Maynard, 1951; Cooke, 2002). LCs have virtually identical synchronized activity, but their intrinsic ionic conductances can be highly variable (Ransdell et al., 2013a). In Chapter 1, we exploit this variability by pharmacologically blocking a subset of their conductances to make LCs hyperexcitable and desynchronize their activity. We find that homeostatic compensation restores synchronized activity and excitability within one hour. This happens via two synergistic mechanisms: the membrane properties of each cell are re-tuned to converge on similar voltage activity, and increased conductance of the gap junctions between the cells helps to buffer away differences in their voltage activity. A separate but related study asked whether naturalistic perturbations of network activity would also result in desynchronization. Neuromodulation provides flexibility in the output of neural networks by altering a subset of their conductances. We hypothesized that this could also cause desynchronization. We found that modulation with serotonin and dopamine both increased the excitability of the CG. Interestingly, serotonin desynchronized the CG, but dopamine did not. We found that dopaminergic modulation directly increases gap junctional conductance. By co-applying these modulators, we found dopamine was able to prevent serotonin from desynchronizing the network without occluding its effects. It was also able to prevent the desynchronization caused by ion channel blockers. Finally, to fully understand the output of LCs, we must recognize that their activity arises not only from their intrinsic properties, but also from their synaptic drive from pacemaker cells. To address how variable this can be from one animal to the next, we analyze the activity of 131 animals taken over the course of approximately 5 years. We use this to address the fundamental question of how variable networks underlying a particular behavior can be across animals. We recognize two distinct classes of pacemaker inputs to LCs, and characterize bursting patterns for both types of pacemaker spike and LC output. We conclude that LCs from different animals receive different temporal patterns of pacemaker drive, which may have important functional implications. We also compare animals from winter and summer months, and find that temperature-independent seasonal effects may explain some of the variance in our data.Includes bibliographical references

The effect of ratio and interval training on Pavlovian-instrumental transfer in mice.

Conditional stimuli (CS) that are paired with reward can be used to motivate instrumental responses. This process is called Pavlovian-instrumental transfer (PIT). A recent study in rats suggested that habitual responses are particularly sensitive to the motivational effects of reward cues. The current experiments examined this idea using ratio and interval training in mice. Two groups of animals were trained to lever press for food pellets that were delivered on random ratio or random interval schedules. Devaluation tests revealed that interval training led to habitual responding while ratio training produced goal-directed actions. The presentation of CSs paired with reward led to positive transfer in both groups, however, the size of this effect was much larger in mice that were trained on interval schedules. This result suggests that habitual responses are more sensitive to the motivational influence of reward cues than goal-directed actions. The implications for neurobiological models of motivation and drug seeking behaviors are discussed

Product Market Competition and Human Resource Practices: An Analysis of the Retail Food Sector

The rise of super-centers and the entry of Wal-Mart into food retailing have dramatically altered the competitive environment in the industry. This paper explores the impact of such changes on the labor market practices of traditional food retailers. We use longitudinal data on workers and firms to construct new measures of compensation and employment, and examine how these measures evolve within and across firms in response to changes in product market structure. An additional feature of the analysis is to combine rich case study knowledge about the retail food industry with the new matched employer-employee data from the Census Bureau.

Structural balance emerges and explains performance in risky decision-making.

Polarization affects many forms of social organization. A key issue focuses on which affective relationships are prone to change and how their change relates to performance. In this study, we analyze a financial institutional over a two-year period that employed 66 day traders, focusing on links between changes in affective relations and trading performance. Traders' affective relations were inferred from their IMs (>2 million messages) and trading performance was measured from profit and loss statements (>1 million trades). Here, we find that triads of relationships, the building blocks of larger social structures, have a propensity towards affective balance, but one unbalanced configuration resists change. Further, balance is positively related to performance. Traders with balanced networks have the "hot hand", showing streaks of high performance. Research implications focus on how changes in polarization relate to performance and polarized states can depolarize

What happened to the 'Great American Jobs Machine'?

In the 1980s and 1990s the US employment rate increased steadily, and by 2000 it was one of the highest among the rich democratic nations. Since then it has declined both in absolute terms and relative to other countries. We use an in- depth comparison between the United States and the United Kingdom to probe the causes of America's poor recent performance. Contrary to a common narrative, a comparative perspective suggests that the decline in US labour force participa-tion is not confined to the (white) male population; the divergence in the female participation rate is even more pronounced. We do not find evidence that the poor US performance is linked to cyclical patterns, such as the 2008–09 Great Recession; instead, it is a more pervasive, longer- run phenom-enon. The relative decline of US participation rates compared to the UK is attributable to shifts in socio- demographic characteristics, such as education, and to shifts in the impact of those characteris-tics, which have become more adverse to participation

Prudential regulatory risk governance of IT multi-sourcing strategies within the Australian banking sector

Banks employ different IT sourcing strategies to reduce IT costs. Australian banks are highly regulated by the Australian Prudential Regulatory Authority (APRA). We selected the two largest Australian banks, Westpac Banking Corporation (WBC) and Commonwealth Bank of Australia (CBA) to investigate the complexity of their IT multi-sourcing models and associated risks. We analysed public documents to reveal the IT sourcing trends from 2009 to 2013, and compared the alignment of the banks' risk frameworks with the APRA risk framework. Finally we reviewed APRA's risk management at the finance industry level and identified that neither risk management nor governance is performed and/or reported by APRA to the Reserve Bank of Australia. Therefore to ensure the cumulative effect of the banks' IT sourcing strategies are measured and reported at the industry level, it is recommended that APRA develops and implements an industry-level risk framework mirroring standard APS 115