Mobile Microscopic Sensors for High-Resolution in vivo Diagnostics
Molecular electronics and nanoscale chemical sensors could enable constructing microscopic sensors capable of detecting patterns of chemicals in a fluid. Information from a large number of such devices flowing passively in the bloodstream allows estimating properties of tiny chemical sources in a macroscopic tissue volume. We use estimates of plausible device capabilities to evaluate their performance for typical chemicals released into the blood by tissues in response to localized injury or infection. We find the devices can readily discriminate a single cell-sized chemical source from the background chemical concentration, providing high-resolution sensing in both time and space. By contrast, such a chemical source would be difficult to distinguish from background when diluted throughout the blood volume as obtained with a blood sample.
(to appear in Nanomedicine: Nanotechnology, Biology, and Medicine)
Related posts:
High-Resolution Glyph-Inspection Based Security System...
Representative Image Thumbnails: Automatic and Manual...
Fusion of Active and Passive Sensors for Fast 3D Capture...
Image noise estimation using color information...
T-Mobile Was Not the Problem with Twitter...
High-Resolution Maps of Science...
Comparative Advantage and Efficient Advertising in the Attention Economy
We analyze the problem that enterprises face when having to decide on the most effective way to advertise several items belonging to their inventories within the company's webpages. We show that the ability to arbitrarily partition a website among items leads to a comparative advantage among webpages which can be exploited so as to maximize the total utility of the enterprise. This result, which also applies to the case of several competitive providers, is then extended to dynamical scenarios where both the advertising allocation and the exposure levels vary with time.
Related posts:
Blogging at work and the corporate attention economy...
Persistence and Succcess in the Attention Economy...
A Comparative Study on Secure Network Virtualization...
A Persistence Paradox...
Novelty and Collective Attention...
Proportional response dynamics leads to market equilibrium...
Rhythms of Social Interaction: Messaging within a Massive Social Network
We have analyzed the fully anonymized headers of 362 million messages exchanged by 4.2 million users of Facebook, an online social network of college students, during a 26 month interval. The data reveal a number of strong daily and weekly regularities which provide insights into the time use of college students and their social lives, including seasonal variations. We also examined how factors such as school affiliation and informal online "friend" lists affect the observed behavior and temporal patterns. Finally, we show that Facebook users appear to be clustered by school with respect to their temporal messaging patterns.
Full citation:
Scott A. Golder, Dennis Wilkinson and Bernardo A. Huberman. "Rhythms of Social Interaction: Messaging within a Massive Online Network" 3rd International Conference on Communities and Technologies (CT2007). East Lansing, MI. June 28-30, 2007.
Related posts:
Friendlee: A Mobile Application for Your Social Life...
Social networks that matter: Twitter under the microscope...
Friends and foes: Ideological social networking...
Pffft! Social Graph, We Need the Portable Social Network...
Inferring Preference Correlations from Social Networks...
Who Should I Follow? Recommending People in Directed Social Networks...
Optimal Bidding Strategy for Keyword Auctions and Other Continuous-time Markets
This paper models continuous-time mass bidding markets, such as keyword auctions and market-based resource allocation systems, as a stochastic dynamic system that fluctuates around an average value under the influence of its users. The user's objective to maximize his long-term average utility is formulated as a stochastic control problem. The optimal bidding strategy is calculated both analytically and numerically. It is shown that market fluctuations tend to decrease expected system revenue, thus search engines like Google and Yahoo has an incentive to create a secondary stable market such as a futures market or a reservation market.
Related posts:
Budget Constrained Bidding in Keyword Auctions and Online Knapsack Problems...
Quantum Auctions...
Optimal Auction Design and Equilibrium Selection in Sponsored Search Auctions...
Efficiently Generating k-Best Solutions to Procurement Auctions...
Experiments with Probabilistic Quantum Auctions...
A Game-theoretic Framework for Creating Optimal SLA/Contract...
Assessing the Value of Cooperation in Wikipedia
Since its inception six years ago, the online encyclopedia Wikipedia has accumulated 6.40 million articles and 250 million edits contributed in a predominantly undirected and haphazard fashion by 5.77 million unvetted contributors. Since it is not obvious that this kind of large-scale, voluntary effort can produce good results, we measured the correlation between the 50 million edits in the English-language Wikipedia and the quality of its 1.5 million articles. We found that article quality is indeed correlated with both number of edits and number of distinct editors. An analysis of editing patterns shows a heavy-tailed distribution of articles, in which relatively few articles having disproportionally high numbers of edits and editors end up at the forefront in terms of quality and visibility.
Related posts:
Assessing the Value of Investments in Network Security Operations: A Systems Analytics Approach...
Assessing the printability of web sites...
Normann’s Crane 2.0 Operationalising Service Systems co-design...
Assessing Respondent-Driven Sampling...
Assessing client maturity: a key to successful outsourcing...
Cooperation in evolving social networks...
Proportional response dynamics leads to market equilibrium
One of the main reasons of the recent success of peer to peer (P2P)
file sharing systems such as BitTorrent is its built-in tit-for-tat
mechanism. In this paper, we model the bandwidth allocation in a P2P
system as an exchange economy and study a tit-for-tat dynamics,
namely the proportional response dynamics, in this economy. In a
proportional response dynamics each player distributes its good to
its neighbors proportional to the utility it received from them in
the last period. We show that this dynamics not only converges but
converges to a market equilibrium, a standard economic
characterization of efficient exchanges in a competitive market. In
addition, for some classes of utility functions we consider, it
converges much faster than the classical tatonnement process and any
existing algorithms for computing market equilibria.
Related posts:
Bilateral and Multilateral Exchanges for Peer-Assisted Content Distribution...
Delivering Energy Proportionality with Non Energy-Proportional Systems-Optimizing the Ensemble...
Optimal Bidding Strategy for Keyword Auctions and Other Continuous-time Markets...
International School on Complexity...
Efficient and Adaptive Proportional Share I/O Scheduling...
Optimal Auction Design and Equilibrium Selection in Sponsored Search Auctions...
Novelty and Collective Attention
The subject of collective attention is central to an information age where millions of people are inundated with daily messages. It is thus of interest to understand how attention to novel items propagates and eventually fades among large populations. We have analyzed the dynamics of collective attention among one million users of an interactive website -digg.com- devoted to thousands of novel news stories. The observations can be described by a dynamical model characterized by a single novelty factor. Our measurements indicate that novelty within groups decays with a stretched-exponential law, suggesting the existence of a natural time scale over which attention fades within large groups.
Related posts:
Popularity, novelty and attention...
Blogging at work and the corporate attention economy...
Crowdsourcing, Attention and Productivity...
Persistence and Succcess in the Attention Economy...
Understanding Collective and Collaborative...
Peering through the fog…...
Does Principal-Agent Theory Work?
We study the agency problem experimentally focusing on two issues that are central to its effectiveness. The first tests whether an incentive compatible direct revelation mechanism performs well when human agents are asked to report probabilistic information. The second addresses the principals lack of knowledge as to how effort levels relate to the final outcome. Our results reveal several behavioral effects that reduce the efficiency of the principal-agent mechanism. We find out that human agents underestimate low probabilities and overestimate high probabilities, introducing errors into what should be a truth-telling mechanism. Furthermore, principals were observed to underpay their agents by substantial amounts. These behavioral issues may explain why contracts designed through standard principal-agent models are seldom used in practice.
Related posts:
A Peer to Peer collaboration agent for desktop applications...
Solo Agents Needed...
Designing the Ad Auctions Game for the Trading Agent Competition...
Investment Tournaments: When Should a Rational Agent Put All Eggs in One Basket?...
A Logical and Computational Theory of Located Resource...
A Logical and Computational Theory of Located Resource...
A Statistical Approach to Risk Mitigation in Computational Markets
We study stochastic models to mitigate the risk of poor Quality-of-Service (QoS) in computational markets. Consumers who purchase services expect both price and performance guarantees. They need to predict future demand to budget for sustained performance despite price fluctuations. Conversely, providers need to estimate demand to price future usage. The skewed and bursty nature of demand in large-scale computer networks challenges the common statistical assumptions of symmetry, independence, and stationarity. This discrepancy leads to underestimation of investment risk. We confirm this non-normal distribution behavior in our study of demand in computational markets.
Related posts:
On Identity Assurance in the Presence of Federated Identity Management Systems...
On Identity Assurance in the Presence of Federated Identity Management Systems...
Towards an Analytic Approach to Evaluate Enterprises’ Risk Exposure to Social Networks...
Using assurance models to aid the risk and governance lifecycle...
International School on Complexity...
Admission Control in a Computational Market...
Follow the Trend or Make a Difference: The Evolution of Collective Opinions
No aspect of the massive participation in content creation that the web enables is more evident than in the countless number of opinions, news and product reviews that are constantly posted on the Internet. Given their importance we have analyzed their temporal evolution in a number of scenarios. We have found that (1) Ignorance of previous views leads to a uniform sampling of the range of opinions among a community. (2) Exposure of previous opinions to potential reviewers induces a trend following process which leads to the expression of increasingly extreme views. (3) When the expression of an opinion is costly and previous views are known, a selection bias softens the extreme views, as people exhibit a tendency to speak out differently from previous opinions. These findings are not only robust but also suggest simple procedures to extract given types of opinions from the population at large.
Related posts:
How public opinion forms...
How public opinion forms...
Understanding Collective and Collaborative...
The Flattening Internet Topology: Natural Evolution, Unsightly Barnacles or Contrived Collapse?...
Web Trend Map v3.0...
Public discourse in the web does not exhibit group polarization...
