102,148 research outputs found
Correspondence: a cyber disagreement
No full textPolicymakers and pundits have been sounding alarms about internet insecurity for years, so the first appearance of anything in International Security (IS) on this topic is a welcomed development. In the fall 2013 issue, Lucas Kello takes the security studies community to task for ignoring cyber perils, while Erik Gartzke argues that cyberwar is of limited political utility.1 Kello writes that “[t]he Clausewitzian philosophical framework misses the essence of the cyber danger and conceals its true significance: the virtual weapon is expanding the range of possible harms between the concepts of war and peace, with important consequences for national and international security” (p. 22). Gartzke counters, “War is fundamentally a political process, as Carl von Clausewitz famously explained. … The internet is generally an inferior substitute for terrestrial force in performing the functions of coercion or conquest” (p. 42). If Kello is right, then the long silence in IS on cybersecurity suggests that scholars have neglected a major transformation in security affairs. If Gartzke is right, then scholars can be forgiven their bemusement with inflated cyber rhetoric
Supplemental Material - Evolution of explorative and exploitative search strategies in collective foraging
No full textSupplemental Material for Evolution of explorative and exploitative search strategies in collective foraging by Ketika Garg, Paul E Smaldino, and Christopher T Kello in Collective Intelligence.</p
Factors affecting in vitro propagation of cassava (Manihot esculenta Crantz.) Euphorbiaceae, varieties of ‘Kello’ and ‘Qulle’
No full textCassava (Manihot esculenta Crantz.) is a perennial shrub of the Euphorbiaceae family native of eastern tropical South America, grown in the tropics of Africa and Asia for its tuberous roots. Its cultivation is constrained by several problems including the use of cuttings infected with diseases and pests, the lack of high quality seed, low productivity, high heterozygosity, low fertility, poor seed set and seed germination. The objective of this study was to find the optimal conditions for micropropagation of two varieties of cassava released for farmers for the production of high quality planting materials. These include determination of the effect of temperature on bud-break of mother plants, differences in concentrations of salt, sucrose, and thidiazuron (TDZ) in a semi-solid MS medium, pH, two-step MS medium and repeated subcultures. The mean number of shoots per plant for axillary bud-break was highest (10.8) at 26°C for that from ‘Kello’ and 9.8 at 30°C for that from ‘Qulle’. The highest mean number of shoots per explant was obtained on MS medium containing 0.2 mg/L TDZ for both varieties on both semi-solid and two-step MS medium culture system. Maximum mean shoot number was obtained on MS medium of a quarter and full salt strength for ‘Kello’ and ‘Qulle’, respectively. The highest mean number of shoots per explant for ‘Kello’ (4.10) and ‘Qulle’ (2.40) was obtained at pH 5.6 and 6.6, respectively. ‘Kello’ produced 3.70 shoots per explant on MS medium containing 1.5% sucrose. Repeated subculturing of ‘Qulle’ resulted in gradual loss of multiplication rate from the third subculture onwards. The present study contributes to optimization of micropropagation of cassava.Key words/phrases: Liquid medium, Salt strength, Shoot multiplication, Sucrose, TDZ
Letter, [Author unclear] to Paulina T. Merritt
No full textHandwritten letter to Paulina Merritt from an unknown author, October 1, 1876.
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An Extended, Dynamic Account of Collaborative Remembering and Information Search
No full textOur memories are collections of the information we have experienced and learned over the course of our lives. While the nature of memory has been studied extensively in the history of the cognitive and psychological sciences, relatively little is known about how we sift through that information space to bring up any given thought at a given moment. According to the extended, dynamical systems framework, the mind is interwoven inextricably into its environment, and so the process of memory retrieval must be considered from a contextually-situated perspective. The goal of the current project is to highlight the importance of a key component of any memory system’s context: the social interactive context. Using both empirical and computational methodologies, the interdisciplinary studies described herein compare the processes employed by individuals and collaborating dyads while searching through information space. Inspiration is drawn from the domains of ecological foraging and particle diffusion in statistical physics to explain foraging dynamics, and from complex systems science to explore collaboration dynamics.Ultimately, the project argues that not only is the social collaborative context an important modulator of memory processes at an individual level, but that in some cases people might be able to coordinate their memory processes, coming together to act as one. Through technological advancements, we are increasingly able to communicate and work collaboratively on all sorts of projects. Thus, a call is made for ongoing research to consider the conditions in which we can optimize information retrieval in these collaborative scenarios.This dissertation, An Extended, Dynamic Account of Collaborative Remembering and Information Search, is submitted by Janelle Szary in 2015 in partial fulfillment of the degree Doctor of Philosophy in Cognitive and Information Sciences at the University of California, Merced, under the guidance of dissertation committee co-chairs Rick Dale and Christopher T. Kello
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The Complexity Matching hypothesis for human communication
No full textThe study of human communication incorporates disciplines across the sciences and the humanities. One question that is important for better understanding and explaining human communication is how information is transmitted from one person to another person during an interaction. To communicate, humans produce and perceive complex behaviors such as vocalizations and body movements. Although researchers are beginning to better understand the production and perception of communicative behaviors, less work has focused on investigating the functions of these behaviors for information transmission during an interaction. Here, in collaboration with various co-authors, I present a hypothesis for human communication that has specific predictions for information transmission across individuals during an interaction.The Complexity Matching hypothesis for human communication suggests that when the complex, hierarchical patterns of communicative behavior between individuals match, information transmission is enhanced. This hypothesis is motivated by work in statistical mechanics showing that when complex properties of two networks match, information transmission across the networks is optimal. In this dissertation, I present three projects that seek to test the Complexity Matching hypothesis for human communication.First, I present initial observations of the production and convergence of hierarchical patterns of vocalizations during conversation. This study provides initial support for the Complexity Matching hypothesis and provides insights into the hierarchical properties of communicative behavior.Next, I test the key prediction of the Complexity Matching hypothesis for human communication: enhanced information transmission. Pairs of adults were given a dyadic problem-solving task of building a tower structure out of a limited amount of materials. We observed that dyads built taller tower structures when their hierarchical patterns of vocalizations and body movements matched. These results provide initial support for the information transmission prediction of the Complexity Matching hypothesis.Finally, I investigate the development of hierarchical structure in human communication. This study follows daylong vocal recordings of infants and their caregivers across the first two years of life. We observed evidence for hierarchical patterns of vocalizations at the earliest recordings session (second week of life) and a dynamic trajectory of complexity matching and other vocal coordination patterns across development.This dissertation, The Complexity Matching Hypothesis for Human Communication, is submitted by Drew H. Abney in 2016 in partial fulfillment of the degree Doctor of Philosophy in Cognitive and Information Sciences at the University of California, Merced, under the guidance of dissertation committee chair Christopher T. Kello
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From a Dyad to a Flock – Complexity Matching to Loose Coupling
No full textRanging over a wide array of interactions, coordination comprises the simple to complex interactions that occur within our daily lives. Many events we encounter ask us to work alone or
with a group to achieve a common goal. These goals frequently set the stage for how we find a
deeper understanding of underlying principles of coordination. Here, began by focusing on the
interaction between two individuals cooperating, and how coupling strength could modulate the
connection shared between them. In these initial studies we found that principles and measures of
complexity matching applied similarly within and between individuals, and perceptual-motor
performance can be facilitated by loose response coupling. We concluded that complexity matching
observed between individuals can similarly occur within one individual, suggesting a general
principle of interaction at work. When response coupling was absent in the dyadic condition, the
degree of complexity matching was significantly reduced. The connection shared between the
coupled cooperative agents influenced their overall shared success. Expanding upon this research,
we asked investigated coordination within larger groups. To do this, we need to find a situation that
fit within coordination but allowed for larger group sizes.
A situation that fit these criteria existed in collective foraging. Collective foragers can
coordinate and cooperate flexibly over time despite changes to task demands, connectedness, and
environmental conditions. The coupling strength linking foragers together often shapes their
collective movements. Based on this, we created a scenario where varying degrees of coupling
strength bound cooperative agents together as they collectively coordinated their actions in search
of hidden targets. We found that loose and flexible coupling among search agents improved
collective performance, and that human players improved performance partly by subtle, indirect
effects on group interactions. Loose coupling emerged among agents when the rules of interaction
were weak enough for agents to act independently or interdependently, while still being strong
enough to help hold them together. Movement patterns showed loose coupling enabled collections
of agents to self-organize and reorganize into a greater diversity of ad hoc groupings. We continued
this work by investigating the link between cooperative interactions among larger groups of agents,
coupling strength, and group member effectiveness. By manipulating group member effectiveness,
group members performed the search task better than before, but without human intervention, the
individual movements of the more-optimal agents continued to lag humans. Based on these results,
we successfully instilled a unique agent with a form of memory which helped them to act in more
‘human-like’ ways.
Taken together, this dissertation supports a broader narrative where coordination depends on
the loose, and flexible alignment of available actions (Glassman, 1973; Kloos & Van Orden, 2009).
This adaptive reorganization of behaviors is supported by an exchange of information, dependent
upon the connections linking complex networks together (Nordham, Tognoli, Fuchs, & Kelso,
2018; Rigoli, Holman, Spivey, & Kello, 2014; Schloesser, Kello, & Marmelat, 2019; West,
Geneston, & Grigolini, 2008). Future work may continue to uncover the underpinnings of
interpersonal coordination – with humans, engineered agents, or both
Handwritten biographical information on Paulina T. McClung Merritt
No full textA handwritten biography of Paulina T. McClung Merritt by an unknown author, 1892.
Heterogeneous and tissue-specific regulation of effector T cell responses by IFN-gamma during Plasmodium berghei ANKA infection.
No full textIFN-γ and T cells are both required for the development of experimental cerebral malaria during Plasmodium berghei ANKA infection. Surprisingly, however, the role of IFN-γ in shaping the effector CD4(+) and CD8(+) T cell response during this infection has not been examined in detail. To address this, we have compared the effector T cell responses in wild-type and IFN-γ(-/-) mice during P. berghei ANKA infection. The expansion of splenic CD4(+) and CD8(+) T cells during P. berghei ANKA infection was unaffected by the absence of IFN-γ, but the contraction phase of the T cell response was significantly attenuated. Splenic T cell activation and effector function were essentially normal in IFN-γ(-/-) mice; however, the migration to, and accumulation of, effector CD4(+) and CD8(+) T cells in the lung, liver, and brain was altered in IFN-γ(-/-) mice. Interestingly, activation and accumulation of T cells in various nonlymphoid organs was differently affected by lack of IFN-γ, suggesting that IFN-γ influences T cell effector function to varying levels in different anatomical locations. Importantly, control of splenic T cell numbers during P. berghei ANKA infection depended on active IFN-γ-dependent environmental signals--leading to T cell apoptosis--rather than upon intrinsic alterations in T cell programming. To our knowledge, this is the first study to fully investigate the role of IFN-γ in modulating T cell function during P. berghei ANKA infection and reveals that IFN-γ is required for efficient contraction of the pool of activated T cells
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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