Detection of Forces and Body Load in Standing and Walking in the American Cockroach

Sense organs in the legs that detect body weight are an important component in the regulation of posture and locomotion. This thesis seeks to gain an understanding of how body weight is detected by sense organs of the legs, and determine how this information influences muscle activities in standing and walking. The first study tested the ability of tibial campaniform sensilla (receptors that monitor forces in the cockroach leg) to encode variations in body load using magnets attached to the thorax. Recordings of sensory activities in freely standing animals showed that proximal tibial sensilla (oriented perpendicular to the leg long axis) encode the level of body load while distal receptors (oriented parallel) fired to decreasing loads. In some postures, sensillum discharges paralleled changes in activity of the trochanteral extensor muscle consistent with a known interjoint reflex. These findings demonstrate that tibial campaniform sensilla can monitor the effects of body weight upon the legs and may aid in generating support of body load. In the second study, sensory activities were compared when animals walked freely in an arena, or upon an oiled glass plate with their body weight supported. Sensilla discharges persisted but were abbreviated when body load was reduced. The results suggest that sensory discharges early in stance result from forces generated by contractions of muscles that press the leg against the substrate. Force feedback later in stance may adjust motor output to changes in loading. In the third study, muscle activities and leg movements were recorded before and after denervation of distal leg segments. Regular bursts occurred in motoneurons to leg extensor muscles following denervation, including ‘fictive’ bursting in a muscle whose tendon (apodeme) was cut in the ablation. Similar motoneuron activities were found in walking on an oiled glass surface, when effects of body weight and mechanical coupling were minimized. When distal segments were completely severed, leg use and muscle bursting were disrupted but could be restored if the stumps were pressed against the substrate. These results support the hypothesis that feedback from receptors in proximal leg segments, that indicate forces, allow for active leg use in walking

Differences in lean and obese skeletal muscle myoblasts of adult and post-natal LA/N (faf) rats: a confocal description of the skeletal muscle myoblast

Mutant strains of obese rats are currently being studied to reveal the mechanisms of increased lipid synthesis and decreased lipid oxidation in these rats. It was originally thought that much of the fat production that leads to obesity is the result of metabolic processes in the liver and adipose tissue. Studies by Kahle et al.3 showed that the liver and adipose tissue account for only 22% and 7% respectively, of total fatty acid synthesis. It was also shown that 21 % of total de novo fatty acid was localized in the postural skeletal muscle. The dry weight of the body is 40% skeletal muscle, thus it is likely that this tissue type has some role in controlling the body’s metabolism.1 Previous work has gone into characterizing differences present within the skeletal muscle of lean and obese phenotypes that may have an influence on metabolism. Electron microscopy was used to determine structural differences in skeletal muscle tissue as well as in myoblasts. It was shown that the myoblasts of the obese phenotype have a higher capacity metabolic synthesis. The work of this thesis was done in order to further investigate some of these previously studied parameters. The focus of this work was to characterize differences in metabolic potential in skeletal muscle myoblasts of the obese and lean phenotypes of the rodent model, the LA/Nfat rat. One important parameter in question is the amount of intracellular lipid deposits present within the individual myoblasts. To determine differences between the two phenotypes, confocal microcopy was used to visually observe, with a lipid specific probe nile red, both intracellular lipid concentration and lipid distribution within the cell. After digitally capturing micrographs into specifically designed computer software, it was possible to determine the amount of fluorescence present within a single cell in a culture. Post-natal (14 days of age) animals were also studied in the same manner to determine if pre-obese pups (Figure 1b) showed the same situation as their adult counterparts. The results of the experiment indicated a significant difference (p \u3c 0.50) present within the lipid content between obese and lean adult rats. The same situation was not shown in post-natal animals. The size of the cells studied however, differed significantly (p \u3c 0.05) between the two age groups studied, but not within them. This difference may be directly attributable to the increased rate of mitosis of the post-natal myoblasts. This increased rate of mitosis may also explain the similarity in lipid content of the obese and lean pups. Another parameter briefly examined was the role of the mitochondria in the metabolism of the cell. No results were attained from the mitochondrial studies. Skeletal muscle has recently been proven to be an important tool in the delivery of proteins and drugs throughout the body. It has been shown that hybrid skeletal muscle myotubes can be used to deliver such necessary proteins as dystrophin and human growth hormone.33-37 Using this type of myoblast-mediated gene therapy it may be possible with continued study to determine regulatory hormones in lipid metabolism. These hormones when delivered to the body in the correct manner may be used as an effective means to not only study the effect of certain drugs on metabolism but perhaps as an effective treatment to obesity

Emergency Behavior for a Connected Smartphone

Smartphones today are capable of being connected to one or more devices via wireless communication technologies, such as Bluetooth®. While a smartphone is connected (or “paired”) with a device, an audio-distribution profile of the smartphone governs routing of audio to and from mechanisms (e.g., speakers, microphones) of either the smartphone or a device to which the smartphone is paired. A protocol that routes audio, based on an input telephone number being an emergency telephone number, is described

Photocathode Quantum Efficiency of Ultra-Thin Cs2Te Layers On Nb Substrates

The quantum efficiencies (QE) of photocathodes consisting of bulk Nb substrates coated with thin films of Cs2Te are reported. Using the standard recipe for Cs2Te deposition developed for Mo substrates (220 {\AA} Te thickness), a QE ~11% - 13% at light wavelength of 248 nm is achieved for the Nb substrates, consistent with that found on Mo. Systematic reduction of the Te thickness for both Mo and Nb substrates reveals a surprisingly high residual QE ~ 6% for a Te layer as thin as 15 {\AA}. A phenomenological model based on the Spicer 3-Step model along with a solution of the Fresnel equations for reflectance, R, leads to a reasonable fit of the thickness dependence of QE and suggests that layers thinner than 15 {\AA} may still have a relatively high QE. Preliminary investigation suggests an increased operational lifetime as well. Such an ultra-thin, semiconducting Cs2Te layer may be expected to produce minimal ohmic losses for RF frequencies ~ 1 GHz. The result thus opens the door to the potential development of a Nb (or Nb3Sn) superconducting photocathode with relatively high QE and minimal RF impedance to be used in a superconducting radiofrequency (SRF) photoinjector.Comment: 12 pages, 3 figure

A Printmaker’s Field Guide: A Chronicle of Artistic Succession Through Printmaking

This series of prints highlights the intricacy, inherent beauty, and ecological importance of plants in a format that bridges our indoor, synthetic tendencies with the complexity and beauty of the natural world. This work connects viewers with the natural world through my deeply rooted curiosity by using techniques that mimic natural processes, propagation, and artistic succession to depict the interactions between the environments and these plants. â€

Unsupervised Bias Detection in College Student Newspapers

This paper presents a pipeline with minimal human influence for scraping and detecting bias on college newspaper archives. This paper introduces a framework for scraping complex archive sites that automated tools fail to grab data from, and subsequently generates a dataset of 14 student papers with 23,154 entries. This data can also then be queried by keyword to calculate bias by comparing the sentiment of a large language model summary to the original article. The advantages of this approach are that it is less comparative than reconstruction bias and requires less labelled data than generating keyword sentiment. Results are calculated on politically charged words as well as control words to show how conclusions can be drawn. The complete method facilitates the extraction of nuanced insights with minimal assumptions and categorizations, paving the way for a more objective understanding of bias within student newspaper sources.Comment: 7 pages, 5 figures, 3 tables, submitted to AAAI202