Extendable self-avoiding walks

The connective constant mu of a graph is the exponential growth rate of the number of n-step self-avoiding walks starting at a given vertex. A self-avoiding walk is said to be forward (respectively, backward) extendable if it may be extended forwards (respectively, backwards) to a singly infinite self-avoiding walk. It is called doubly extendable if it may be extended in both directions simultaneously to a doubly infinite self-avoiding walk. We prove that the connective constants for forward, backward, and doubly extendable self-avoiding walks, denoted respectively by mu^F, mu^B, mu^FB, exist and satisfy mu = mu^F = mu^B = mu^FB for every infinite, locally finite, strongly connected, quasi-transitive directed graph. The proofs rely on a 1967 result of Furstenberg on dimension, and involve two different arguments depending on whether or not the graph is unimodular.Comment: Accepted versio

The development of a model of Alpha helix formation for transmembrane peptides

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references (leaf 26).Researchers have studied the folding and binding properties of peptides in water for many years, but only recently has anyone attempted to explore those same tendencies in an environment similar to that of a transmembrane protein incorporated into the phospholipid bilayer of the cell. To this end, we have been working on the synthesis of a group of peptides with the general sequence +H3N-Ala2-Leu3-Ala7-Trp-Ala-X-Ala10-Lys6-COOH, where we will substitute all twenty naturally occurring amino acids into position X. We have successfully synthesized and purified the peptide in which the guest position X is filled by an isoleucine-due to the difficulty of the sequence involved, we have been unable to synthesize and purify eighteen of the remaining nineteen. Peptides, once synthesized, are characterized by MALDI mass spectrometry and HPLC and purified peptides are studied using circular dichroism (CD) spectroscopy to determine the a-helicity. Initial results suggest that the transmembrane environment will indeed alter the propensities of the various amino acid residues to form a-helices, though to what degree still remains to be seen. Once complete, this study should make it possible to determine a system for predicting a-helix formation in membrane proteins and determine the basic rules that guide such helix formation

Non-Trivial Off-Path Network Measurements without Shared Side-Channel Resource Exhaustion

Most traditional network measurement scans and attacks are carried out through the use of direct, on-path network packet transmission. This requires that a machine be on-path (i.e, involved in the packet transmission process) and as a result have direct access to the data packets being transmitted. This limits network scans and attacks to situations where access can be gained to an on-path machine. If, for example, a researcher wanted to measure the round trip time between two machines they did not have access to, traditional scans would be of little help as they require access to an on-path machine to function. Instead the researcher would need to use an off-path measurement scan. Prior work using network side-channels to perform off-path measurements or attacks relied on techniques that either exhausted the shared, finite resource being used as a side-channel or only measured basic features such as connectivity. The work presented in this dissertation takes a different approach to using network side-channels. I describe research that carries out network side-channel measurements that are more complex than connectivity, such as packet round-trip-time or detecting active TCP connections, and do not require a shared, finite resource be fully exhausted to cause information to leak via a side-channel. My work is able to accomplish this by understanding the ways in which internal network stack state changes cause observable behavior changes from the machine. The goal of this dissertation is to show that: Information side-channels can be modulated to take advantage of dependent, network state behavior to enable non-trivial, off-path measurements without fully exhausting the shared, finite resources they use

Morality Provides Meaning

Previous separate models of meaning in life have suggested that meaning is composed of several components operating across levels of construal. For example, sometimes people might look to a component of meaning in a state of concrete construal to gain a sense of consistency or predictability, and at other times they may look to a component of meaning to create feelings of higher purpose in life. These models of meaning have the potential to shed light not only on the various facets of life that make people feel life is meaningful, but to discover the ways in which these components create feelings of meaning in terms of both predictability as well as purpose. These models also have great potential for understanding the ways in which people compensate for threats to meaning at different levels of construal. The goal of the present investigation was to test the idea that people experience meaning at both concrete and abstract levels of construal, and to assess which types of standards create meaning in live most effectively. Specifically, I tested the hypothesis that morality may be especially effective at creating feelings of both predictability and purpose more effectively than convention. In addition, the present research examined whether or not morality is especially effective at compensating for threats to feelings of predictability and higher purpose compared to convention for these same reasons. These ideas were tested in three studies. In Study 1, participants rated the extent to which two types of standards, conventional standards and moral standards, provide a sense of predictability (i.e. “coherence”) and a sense of 2 purpose (i.e. “transcendence”). In Study 2, participants completed a construal level manipulation designed to induce states of concrete or abstract construal and then rated the extent to which conventional and moral standards provide consistency and purpose. In a third study, participants completed a faux personality inventory and received false feedback suggesting they would live a life characterized by either low or average levels of either predictability (coherence) or purpose (transcendence). The results of Study 1 demonstrated that participants found more coherence and transcendence in their moral standards compared to their conventional standards. In addition, moral standards provided much more transcendence than conventional standards, whereas morality created slightly more coherence than conventional standards. The results of Study 2 showed no effects, and the results of Study 3 demonstrated that participants found their moral standards to be much more important to them than their conventional standards. The overall results of all three studies suggest that people see their moral standards as providing more meaning in life, especially in the form of transcendence, than their conventional standards. The results also suggest that moral standards are generally more important to people than conventional standards. Overall, these results suggest that people may be able to experience a broader sense of purpose in life by focusing on moral standards

Dwelling Poetically, Proceeding Orphically: The Platonic Tradition and the Heideggerian Humanism of Ernesto Grassi

Martin Heidegger exerted an immense influence over twentieth century thought by providing profound insights into the nature of Being as well as scathing social critiques, focused on the destructive force of late modern technological reductionism. As part of Heidegger’s project, he elaborated upon a sophisticated history of Being in which two great monsters of Platonism and Humanism are cast as Antichrist and False Prophet. Subsequently, however, his own student Ernesto Grassi argued that Renaissance Humanism was not a stepping stone towards subjectivism and technological thinking, but rather stood in conformity with the fundamental essence of Heidegger’s own project. This study seeks to perform the same service for the much maligned history of Platonic thinking. After reviewing the important details of the positions held by Heidegger and Grassi in the Introduction and Chapter One, I move on to an examination of the history of the interpretation of Plato in Chapter Two. Here I show that, when we approach Plato correctly, his thought conforms to insights later offered by Heidegger and Grassi. In the remaining chapters of the study, I demonstrate that this misunderstanding afflicts not only Plato himself, but it has also affected the interpretation of the entire Neoplatonic tradition. Thus, in Chapter Three, I show that Plotinus receives and expands upon the core insights which Plato possessed, and that Platonism’s role in the development of technological enframing has been gravely mistaken. In Chapter Four, I show how the later integration of Neoplatonic thought into some of the greatest Christian Platonists did nothing to eliminate these core insights of the Platonic tradition. Finally, in Chapter Five, I show that Marsilio Ficino, the Platonist painted by Grassi as the arch-villain who undermined the Heideggerian project of the Renaissance continued to maintain the fundamental insights of the Platonic tradition. Ultimately, therefore, Platonism, far from being the foundation of technological enframing in the modern era, is able to offer great assistance to the Heideggerian-Grassian project of renewing poetic and rhetorical speech as the foundation of philosophical thinking