Showing papers in "Eureka in 2011"

The Biggest Bugs: An investigation into the factors controlling the maximum size of insects

Abstract: Introduction Modern insects are much smaller than their prehistoric counterparts. The largest extant insect is three times smaller in mass than the heaviest of ancient insects. Whether there are indeed factors that have changed over the 400 million years of insect evolution leading to their smaller size and whether there is a single limiting factor are unsolved questions. In entomology, these two subjects are met with numerous conjectures; a proper analysis of them all would require a lengthy treatise. For the sake of brevity, this review looks at some of the most familiar suspects: the insect tracheal system, changes in atmospheric oxygen content over earth history and the evolution of flight. Other perhaps less common theories such as the changes in ecology in insect habitats, the insect exoskeleton, and the evolutionary advantage of being small are also topics of discussion. In this paper, “largeness” and “smallness” will refer to mass as opposed to length, width or volume. However, one cannot often determine mass from insect fossils since some fossils only contain wings or other pieces of an insect’s body. In some articles that have been cited here, only the body length is reported. In these cases, one can only assume that a larger wingspan or longer body means a more massive insect. When the comparison of size switches to wing length, or length, I will make that distinction. I will discuss only adult insects, even though the larval stages of a given species are commonly larger than the adult stage.

Sterol Chemical Structure and Conformation Influence the Thermotropic Phase Behaviour of Dipalmitoylphosphatidylcholine Bilayers

Abstract: Studying the nature of interactions between the sterol ring system and neigbouring phospholipid molecules is important for our understanding of the properties of sterols in biological molecules and the role of such interactions in many disease processes. In this project, the thermotropic phase behaviour of binary dipalmitoylphosphatidylcholine (DPPC)/sterol mixtures with different sterol ring configurations (C5,6 double bond, 5 α -H and 5 β -H orientation and either 3 α -OH, 3 β -OH, 3-ketone functional groups) was investigated using differential scanning calorimetry (DSC) and was compared to earlier studies of cholesterol/ and epicholesterol/DPPC mixtures. Given the differences in the thermodynamic parameters obtained from these mixtures and their associated changes in bilayer stability and miscibility, it is clear that changing the sterol chemical configuration has a significant effect on bilayer properties. Any sterol molecule whose ring structure deviates from that of cholesterol is unlikely to be fully miscible in mammalian membranes.

Biofeedback as a physiological treatment for traumatic psychological injuries

Abstract: For over a century it has been argued that the psychological effects of trauma are often expressed as physiological changes in the biological stress response. Research supports that biofeedback can be used as a tool that increases an individual’s awareness of their physiological response to overwhelming sensations and teaches them how they can take control of it. Literature on trauma suggests the need for physiological-awareness therapy, meanwhile literature on biofeedback indicates that it is a technique that focuses specifically on physiological awareness. Biofeedback is a therapeutic tool that uses sensors to record physiological changes in the stress response and provides an individual with feedback on their current bodily state. However, little research has linked the potential benefits of using biofeedback, in conjunction with other treatments, to help traumatized individuals recover. In 2006, van der Kolk pointed out that little is known about how people can learn to regulate their physiological arousal. He argued that a lack of arousal modulation is a dominant issue in traumatized individuals. In line with this, Hopper et al. (2007) posited that humans have a greater self-regulatory potential than other mammals but that the efficiency of regulation can be impaired in individuals with Post-Traumatic Stress Disorder (PTSD). van der Kolk (2006) also indicated that a traumatizing experience involves an individual’s inability to engage in an action pattern that results in avoidance of the trauma. When a traumatic experience becomes unavoidable, a person can become overwhelmed at the futility of their situation and lose their capacity to use their emotions as guidelines for successful action. van der Kolk further suggested that therapeutic techniques need to be explored in the realm of reprogramming the automatic physiological responses evoked by emotions. Findings show that biofeedback targets an individual’s awareness of their internal physical sensations, which have a reciprocal relationship with a person’s emotional experience. The need for an individual to cope with trauma at a physiological level enhances the value of biofeedback as a necessary tool in this process. Since traumatized individuals have deficits in understanding their own physiology, biofeedback can give them the insight they require to regain their sense of self-control (Ogden, Minton, & Pain, 2006). Therefore the implications are that biofeedback can be used in conjunction with other trauma-related therapies because it addresses the underlying physiological issues of trauma.

Inability of Viral Superantigens to Induce CD4-mediated Islet Transplant Rejection

Abstract: Superantigens have the ability to bypass the specific interactions of the MHC class II and T-cell receptor by binding outside of the peptide binding region and onto the V β chain. This ability allows superantigens to stimulate a wide array of T-cell populations, irrespective of T-cell receptor (TCR) specificity. Research on bacterial and viral superantigens have demonstrated various outcomes ranging from superantigen dependent cellular cytoxicity (SDCC), rheumatoid arthritis, to superantigen stimulated T-cell clonal deletion and anergy. Due to its ability to proliferate a large population of T-cells, this paper asks whether superantigens have a role in islet transplant rejection. We used transgenic V β 6 TCR mice specific for male ‘H-Y’ antigen as recipients to islet transplants. Donors comprised mice expressing endogenous superantigen specific for the V β 6 chain. Transplantation of these donor islets did not induce rejection. Recipients were also primed with ‘H-Y’ antigen to induce a CD4 effector memory T-cell population prior to islet transplantation. Even with primed recipients, donor islet transplants did not induce rejection by recipient transgenic mice.

Organic Amnesia: A Diversity in Deficits

Abstract: Organic amnesia is the loss of memory due to biological factors such as brain disorders, tumors, strokes, degenerative diseases, or any other of a multitude of other disruptions of neurological function. Memories are stored throughout the brain, and as a result damage to any localized brain region only causes limited memory deficits. Even in itself, organic amnesia can present in a variety of impairments across numerous memory systems within the brain. Several kinds of amnesia will be reviewed, including details of the corresponding deficits and suggestions of the likely affected memory system.

Zeno paradox: A relativistic approach to solution

Abstract: Zeno of Elea was brilliant producing paradox [1]; the most famous is the story of Achilles and the tortoise. It can be summarized in these words: Achilles and the tortoise decide to have a race. Because Achilles can run twice as fast as the tortoise he gives her a long head start. Now, says Zeno, by the time Achilles reaches the tortoise’s starting point she would have moved ahead by half the distance of her lead. And by the time Achilles reaches that point she would have moved on by half of that distance. And so on, and so forth, ad infinitum. Achilles is never able to catch up with the tortoise, because at each point, by the time he has covered the distance between them, she will always have moved on further by half of that distance. As Magee [1] points, it is here an impeccable logical argument that leads to a false conclusion. As Borges [2] reports, many previous works had focused looking for a fault in the logic [3] but they all have failed, so Borges suggests looking back to the concept of our world. In this work, we shall use such suggestion focusing in the relativity theory. We are convinced that the inaccessibility of the paradox lies in work under the Galilean transforms in the Newtonian world. Despite this, we will try to see the problem under the Lorentzian transforms in the Eistenian world. For this purpose we first take a look at the paradox in Galilean mathematical terms and then we will look at the paradox under Lorentzian transform.

IR Motion Tracking as a Standard Input Device

Abstract: As our computing needs change and the availability of advanced input systems begin to increase we find that we are coming to the point where current interfaces are beginning to become outdated. Touch interfaces are becoming abundant, but there is only so much that one can do with a 2D input. This project tries to show that there is a potential for IR based interface systems to replace standard mouse input in current as well as future interfaces. Our results show that both the accuracy and robustness of the IR system designed herein are equivalent to that of standard mouse input.