Determination of the Topology of a Directed Network

We consider strongly-connected directed networks of identical synchronous, finite-state processors with in- and out-degree uniformly bounded by a network constant. Via a straightforward extension of Ostrovsky and Wilkerson's Backwards Communication Algorithm in [OW], we exhibit a protocol which solves the Global Topology Determination Problem, the problem of having the root processor map the global topology of a network of unknown size and topology, with running time O(ND) where N represents the number of processors and D represents the diameter of the network. A simple counting argument suffices to show that the Global Topology Determination Problem has time-complexity Omega(N logN) which makes the protocol presented asymptotically time-optimal for many large networks.Comment: 9 pages, no figures, accepted to appear in IPDPS 2002 (unable to attend), (journal version to appear in Information Processing Letters

Gutter King

Gutter King had a threefold purpose: to create a feature film using limited resources, to make the film bridge the gap between a defined artistic aesthetic and its broader distribution goals, and to make the film entertaining to its target market of 14-24 year old males. The methods used: exploiting new digital technology, using a limited workforce (crew), and implementing a planned improvisational structure

Bio-Inspired Synchronization of Pulse-Coupled Oscillators and its Application to Wireless Sensor Networks

Precise synchronization among networked agents is responsible for phenomena as diverse as coral spawning and consistency in stock market transactions. The importance of synchronization in biological and engineering systems has triggered an avalanche of studies analyzing the emergence of a synchronized behavior within a network of, possibly heterogeneous, agents. In particular, synchronization of networks of coupled oscillators has received great attention since limit cycle oscillators are a natural abstraction for systems where periodicity is a distinctive property. Examples of such systems include circadian rhythms and alternate-current power generators. This work deals with synchronization of pulse-coupled limit cycle oscillators (PCOs). A reverse engineering approach is taken with the objective of obtaining an abstraction for PCO networks able to capture the key properties observed in the classical biological PCO model, to finally implement it in an en gineering system. To this end, we first reformulate the PCO model as a hybrid system, able to integrate in a smooth manner the continuous-time dynamics of the individual oscillators and the impulsive effect of the coupling. Using our new model, we analyze the existence and stability of synchronization in a variety of PCO network topologies, starting from the simplest all-to-all network where global synchronization is proven to exist, to end giving synchronization conditions in the general strongly connected network case. Inspired by the strong synchronization properties of PCO networks we design a PCO-inspired time synchronization protocol for wireless sensor networks that enjoys all the advantages of our optimized PCO setup. A pilot implementation is presented going from a simulation stage to a hardware implementation in Gumstix development boards and industrial acoustic sensors. To test the potential of the protocol in a real application, we implement the PCO-based time synchronization protocol in a distributed acoustic event detection system, where a sensor network combines local measurements over an infrastructure-free wireless network to find the source of an acoustic event. An evaluation by simulation is given to illustrate the advantages of using the pulse-coupled synchronization strategy.The contributions of this thesis range from the theoretical synchronization conditions for a variety of PCO networks to the design and implementation of a synchronization strategy for wireless sensor networks that seems to be the natural choice when using an infrastructure-free wireless network due to its simple formulation and natural scalability

The Brigade Combat Team (BCT): A Revolution in Organizational Structure

This paper explores the U.S. Army’s force reorganization around the Brigade Combat Team (BCT), which began in 2002. The BCT shifted how various army units interacted by changing the echelon at which different types of units report to a single commander, essentially creating self-sufficient units of about 2,500 soldiers instead of the previous self-sufficient units of about 15,000 soldiers. This paper utilizes existing organizational theories and research to better understand the implications for such a dramatic change in organizational structure. It contextualizes the army’s reorganization by applying the Rational Actor, Political, and Bureaucratic Models outlined in Essence of Decision by Graham Allison and Philip Zelikow. These models help explain why the army found the restructuring necessary. In changing the organizational structure of the U.S. Army, some processes that existed prior to the BCT became less effective and arguably outdated, such as the army’s decision-making process and personnel management system. At the same time, the army instituted a new communications system which was designed to better integrate disparate units, but was also stymied by the outdated decision-making processes. After understanding these factors, this paper asserts that various new technologies have failed to meet their full potential within the BCT due to ongoing implications related to not satisfactorily adjusting decision-making, communications systems, and personnel management based on the BCT reorganization. These technologies include unmanned aerial vehicles, integrated communications networks, and a particular armored vehicle (known as the Mine Resistant Ambush Protected Vehicle). This paper has implications for non-military organizations which have undergone or are examining the effects of structural reorganization

The rhythm that unites: an empirical investigation into synchrony, ritual, and hierarchy

Synchrony, or rhythmic bodily unison activities such as drumming or cadence marching, has attracted growing scholarly interest. Among laboratory subjects, synchrony elicits prosocial responses, including altruism and empathy. In light of such findings, researchers in social psychology and the bio-cultural study of religion have suggested that synchrony played a role in humanity’s evolutionary history by engendering collectivistic commitments and social cohesion. These models propose that synchrony enhances cohesion by making people feel united. However, such models overlook the importance of differentiated social relations, such as hierarchies. This dissertation builds on this insight by drawing on neuroscience, coordination dynamics, social psychology, anthropology, and ritual studies to generate a complex model of synchrony, ritual, and social hierarchy, which is then tested in an experimental study. In the hypothesized model, shared motor unison suppresses the brain’s ability to distinguish cognitively between self-caused and exogenous motor acts, resulting in subjective self-other overlap. During synchrony each participant is dynamically entrained to a group mean rhythm; this “immanent authority” prevents any one participant from unilaterally dictating the rhythm, flattening relative hierarchy. As a ritualized behavior, synchrony therefore paradigmatically evokes shared ideals of equality and unity. However, when lab participants were assigned to either a synchrony or asynchrony manipulation and given a collaborative task requiring complex coordination, synchrony predicted a marginally lower degree of collaboration and significantly lower interpersonal satisfaction. These findings imply that unity and equality can undercut group cohesion if the collective agenda is a shared goal that requires interpersonal coordination. My results emphasize that, despite the inevitable tensions associated with social hierarchy, complementary roles and hierarchy are vital for certain aspects of social cohesion. Ritual and convention institute social boundaries that can be adroitly negotiated, even as egalitarian effervescence such as communitas (in the sense of Victor Turner) facilitates social unity and inspires affective commitments. These findings corroborate theories in ritual studies and sociology that caution both against excessive emphasis on inner emotive states (such as empathy) and against excessively rigid conventions or roles. An organic balance between unity and functional differentiation is vital for genuinely robust, long-term social cohesion.2018-06-21T00:00:00

Anonymous Armies: Modern “Cyber-Combatants” and Their Prospective Rights Under International Humanitarian Law

Cyber-attacks take many forms, only some of which are applicable to the law of war. This Comment discusses only those attacks sponsored by a government or non-state entity that have the goal of affecting morale or gaining political advantage, or those attacks amounting to tactical strikes on state or civilian infrastructure. In that vein, this Comment proposes the adoption of a new legal framework for determining the threshold that marks a participant in such a cyber-attack as a “cyber-combatant” by adapting the framework set by the Geneva Conventions and existing custom. This definition should encompass cyber-attacks perpetrated by states, unrecognized states, and non-state groups. It should set the rules of engagement for cyber-attacks and operations conducted for political advantage, morale boost, and tactical purposes. Whether they act on the orders or in support of States or non-state groups, those perpetrating cyber-attacks that have material effects upon the morale or infrastructure of a sovereign nation during armed conflict should be treated as “combatants” for purposes of international law, and the legality of their actions should be defined. Because the standard governing what constitutes a lawful combatant under any reasonable reading of the Geneva Conventions is muddled as applied to combatants in cyber-warfare as presently conducted, this paper takes the position that under present custom, cyber-combatants may likely be effectively considered illegal combatants under International Law. Part II of this Comment provides a framework for defining “cyber-combatants,” reviewing the traditionally accepted definition of “combatants” under the Geneva Conventions and customary international law as restated through the Tallinn Manual on the International Law Applicable to Cyber Warfare. Part III explores the alleged cyber-operations of sovereign States, including Israel’s C4i Cyber Warfare Unit and The United States’ USCYBERCOM and its sister agencies, some or all of which may have been responsible for the Stuxnet attack on Iran; Russia’s coordinated cyber-attacks perpetrated during its war with Georgia in 2008 and in the conflict in Ukraine in 2014 and 2015; and China’s PLA Unit 61398. Part IV introduces the unique problem posed by cyber-attacks perpetrated by agents of unrecognized states and organized terrorist groups such as Al-Qaeda and ISIS. Finally, Part V concludes by proposing alternative definitions for cyber-attacks, and consequentially, cyber-combatants

Battle for the Punchbowl: The U. S. 1st Marine Division 1951 Fall Offensive of the Korean War

This study is an operational and tactical study of a battle fought by the U. S. 1st Marine Division near "the Punchbowl," an extinct volcano of military value in the Taebaek Mountains of Korea, from late August through mid September 1951. That engagement was to be the last 1st Marine Division offensive of the Korean War. This battle, for Yoke and Kanmubong Ridges, has received little coverage from historians. That it is all but forgotten is surprising, since it was one of the hardest fought for United States Marines in the war. The casualties were high, and Americans did not understand why so many had to die for a war that seemed to already be set to conclude by negotiations. This study tells the story of that battle more completely than ever before, and assesses its significance to the course of the Korean War

PERIOD3 variable number tandem repeat genotype associations with performance, injury, illness and re-entrainment

Background: Circadian rhythms are internally driven biological variations that fluctuate with a period of approximately 24 hours, even in the absence of external environmental time cues. These rhythms enable organisms to synchronise their internal clock time with external environmental time. This ensures appropriate timing of biological and metabolic processes, and allows anticipation of daily changes in the environment. Circadian rhythms also play an important role in sports in terms of optimising performance time-of-day and aiding adjustment to global time zone changes. Thus, performance, which is under the control of the athlete, may be impacted by event time-of-day scheduling in the new time zone. It has previously been shown that individual sport athletes in South Africa tend to be morning-types and carry the PERIOD3 (PER3) Variable Number Tandem Repeat (VNTR) 5-repeat allele, which has been associated with a preference for mornings. The distribution of the PER3 VNTR polymorphism in combination with an individual's preference for mornings or evenings has not yet been described in team sports. Differences in the PER3 VNTR genotype between team and individual sport athletes are expected, given that individual sport athletes may be free to choose the time-of-day at which they train. In contrast, team sport athletes usually train in groups, thus these individuals may not have the flexibility to choose their preferred training times. There are notable inter-individual differences in adjustment to jet-lag after time zone changes. A possible genetic candidate that may be responsible for some of this variation is the PER3 VNTR gene. This gene consist of two alleles corresponding in size to 4-repeats (PER34) or 5-repeats (PER35). Individuals are either homozygous for the 4-repeat allele (PER⁴⁄⁴) or the 5-repeat allele (PER3⁵⁄⁵), while others are heterozygous for the PER3 gene (PER34/5). The PER3 VNTR genotype might explain individual sensitivity to bright light and has been reported to be associated with sleep pressure- an increase in the brain's pressure and need for sleep, following an extended period of awakening. Individuals homozygous for the longer variant of the gene (i.e. PER3⁵⁄⁵) experience a higher sleep pressure during extended wakefulness. The PER3⁵⁄⁵ genotype has been reported to be more sensitive to the alerting and melatonin suppression effects of blue enriched light than the PER⁴⁄⁴ genotype. Aims: Therefore, the aim of Study 1 was to compare the chronotype and PER3 VNTR genotype distribution of South African Super Rugby players to individuals of low physical activity (i.e. those who are physically active ≤2 times per week). The aim of Study 2 was to determine whether PER3 VNTR genotype might contribute to inter-individual variation in the extent to which game involvement and quality of play are affected following trans-meridian travel. Further, the aim of Study 3 was to compare the impact of time zone travel during the 2012 Super Rugby competition in South African players genotyped as PER⁴⁄⁴, PER34/5 and PER3⁵⁄⁵ on the incidence of illnesses and injuries. Lastly, the aim of Study 4 was to compare the extent to which individuals genotyped as PER⁴⁄⁴ or PER3⁵⁄⁵ respond to appropriately-timed blue light exposure in order to resynchronise their circadian rhythm, following simulated eastward travel, based on changes in dim-light melatonin onset and cortisol circadian phases