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Dynamics of Social Interaction
Curated by Ashish Umre
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The Evolution of the Bioinspired Robot

The Evolution of the Bioinspired Robot | Social Foraging | Scoop.it
To build a better robot, engineers are turning to an experienced problem solver—nature.

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From Social Data Mining to Forecasting Socio-Economic Crisis

Socio-economic data mining has a great potential in terms of gaining a better understanding of problems that our economy and society are facing, such as financial instability, shortages of resources, or conflicts. Without large-scale data mining, progress in these areas seems hard or impossible. Therefore, a suitable, distributed data mining infrastructure and research centers should be built in Europe. It also appears appropriate to build a network of Crisis Observatories. They can be imagined as laboratories devoted to the gathering and processing of enormous volumes of data on both natural systems such as the Earth and its ecosystem, as well as on human techno-socio-economic systems, so as to gain early warnings of impending events. Reality mining provides the chance to adapt more quickly and more accurately to changing situations. Further opportunities arise by individually customized services, which however should be provided in a privacy-respecting way. This requires the development of novel ICT (such as a self- organizing Web), but most likely new legal regulations and suitable institutions as well. As long as such regulations are lacking on a world-wide scale, it is in the public interest that scientists explore what can be done with the huge data available. Big data do have the potential to change or even threaten democratic societies. The same applies to sudden and large-scale failures of ICT systems. Therefore, dealing with data must be done with a large degree of responsibility and care. Self-interests of individuals, companies or institutions have limits, where the public interest is affected, and public interest is not a sufficient justification to violate human rights of individuals. Privacy is a high good, as confidentiality is, and damaging it would have serious side effects for society.

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Time passes more slowly for flies, study finds

Time passes more slowly for flies, study finds | Social Foraging | Scoop.it

Research suggests perception of time is linked to size, explaining why insects find it easy to avoid being swatted

 

Flies avoid being swatted in just the same way Keanu Reeves dodges flying bullets in the movie The Matrix – by watching time pass slowly.

To the insect, that rolled-up newspaper moving at lightning speed might as well be inching through thick treacle.

 

Like Reeves standing back and side-stepping slo-mo bullets, the fly has ample time to escape. And it is not alone in its ability to perceive time differently from us. Research suggests that across a wide range of species, time perception is directly related to size.

 

Generally the smaller an animal is, and the faster its metabolic rate, the slower time passes.

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Turn Your Smartphone Into a Microscope With Single Lens

Turn Your Smartphone Into a Microscope With Single Lens | Social Foraging | Scoop.it

Smartphone users who are itching to photograph objects too small for the naked eye can rest assured — the Micro Phone Lens turns your iPhone or Android camera phone into a portable handheld microscope.

 

The Micro Phone Lens is a soft lens that sticks directly onto the camera lens on the back of your phone. Users can then zoom into 15X magnification in high focus. The minimum camera requirement is 5 megapixels.

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Whose Mind Matters More—The Agent or the Artist? An Investigation of Ethical and Aesthetic Evaluations

Whose Mind Matters More—The Agent or the Artist? An Investigation of Ethical and Aesthetic Evaluations | Social Foraging | Scoop.it

Theory of mind, the capacity for reasoning about mental states such as beliefs and intentions, represents a critical input to ethical and aesthetic evaluations. Did the agent cause harm on purpose? Were those brushstrokes intentional? The current study investigates theory of mind for moral and artistic judgments within the same paradigm. In particular, we target the role of intent for two kinds of judgments: “objective” judgments of quality and “subjective” judgments of preference or liking. First, we show that intent matters more for objective versus subjective judgments in the case of ethics and aesthetics. Second, we show that, overall, intent matters more for ethical versus aesthetic evaluations. These findings suggest that an “objective-subjective” dimension describes judgments across both domains, and that observers assign more weight to the mind of the moral agent than the mind of the artist when making the relevant evaluations.

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Are Hotspots Always Hotspots? The Relationship between Diversity, Resource and Ecosystem Functions in the Arctic

Are Hotspots Always Hotspots? The Relationship between Diversity, Resource and Ecosystem Functions in the Arctic | Social Foraging | Scoop.it

The diversity-ecosystem function relationship is an important topic in ecology but has not received much attention in Arctic environments, and has rarely been tested for its stability in time. We studied the temporal variability of benthic ecosystem functioning at hotspots (sites with high benthic boundary fluxes) and coldspots (sites with lower fluxes) across two years in the Canadian Arctic. Benthic remineralisation function was measured as fluxes of oxygen, silicic acid, phosphate, nitrate and nitrite at the sediment-water interface. In addition we determined sediment pigment concentration and taxonomic and functional macrobenthic diversity. To separate temporal from spatial variability, we sampled the same nine sites from the Mackenzie Shelf to Baffin Bay during the same season (summer or fall) in 2008 and 2009. We observed that temporal variability of benthic remineralisation function at hotspots is higher than at coldspots and that taxonomic and functional macrobenthic diversity did not change significantly between years. Temporal variability of food availability (i.e., sediment surface pigment concentration) seemed higher at coldspot than at hotspot areas. Sediment chlorophyll a (Chl a) concentration, taxonomic richness, total abundance, water depth and abundance of the largest gallery-burrowing polychaete Lumbrineris tetraura together explained 42% of the total variation in fluxes. Food supply proxies (i.e., sediment Chl a and depth) split hot- from coldspot stations and explained variation on the axis of temporal variability, and macrofaunal community parameters explained variation mostly along the axis separating eastern from western sites with hot- or coldspot regimes. We conclude that variability in benthic remineralisation function, food supply and diversity will react to climate change on different time scales, and that their interactive effects may hide the detection of progressive change, particularly at hotspots. Time-series of benthic functions and its related parameters should be conducted at both hot- and coldspots to produce reliable predictive models.

 

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Co-Adaptation and the Emergence of Structure

Co-Adaptation and the Emergence of Structure | Social Foraging | Scoop.it

Co-adaptation (or co-evolution), the parallel feedback process by which agents continuously adapt to the changes induced by the adaptive actions of other agents, is a ubiquitous feature of complex adaptive systems, from eco-systems to economies. We wish to understand which general features of complex systems necessarily follow from the (meta)-dynamics of co-adaptation, and which features depend on the details of particular systems. To begin this project, we present a model of co-adaptation (“The Stigmergy Game”) which is designed to be as a priori featureless as possible, in order to help isolate and understand the naked consequences of co-adaptation. In the model, heterogeneous, co-adapting agents, observe, interact with and change the state of an environment. Agents do not, ab initio, directly interact with each other. Agents adapt by choosing among a set of random “strategies,” particular to each agent. Each strategy is a complete specification of an agent's actions and payoffs. A priori, all environmental states are equally likely and all strategies have payoffs that sum to zero, so without co-adaptation agents would on average have zero “wealth”. Nevertheless, the dynamics of co-adaptation generates a structured environment in which only a subset of environmental states appear with high probability (niches) and in which agents accrue positive wealth. Furthermore, although there are no direct agent-agent interactions, there are induced non-trivial inter-agent interactions mediated by the environment. As a function of the population size and the number of possible environmental states, the system can be in one of three dynamical regions. Implications for a basic understanding of complex adaptive systems are discussed.

 

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Social and Population Structure in the Ant Cataglyphis emmae

Social and Population Structure in the Ant Cataglyphis emmae | Social Foraging | Scoop.it

Dispersal has consequences not only for individual fitness, but also for population dynamics, population genetics and species distribution. Social Hymenoptera show two contrasting colony reproductive strategies, dependent and independent colony foundation modes, and these are often associated to the population structures derived from inter and intra-population gene flow processes conditioned by alternative dispersal strategies. Here we employ microsatellite and mitochondrial markers to investigate the population and social genetic structure and dispersal patterns in the ant Cataglyphis emmae at both, local and regional scales. We find that C. emmae is monogynous and polyandrous. Lack of detection of any population viscosity and population structure with nuclear markers at the local scale suggests efficient dispersal, in agreement with a lack of inbreeding. Contrasting demographic differences before and during the mating seasons suggest that C. emmae workers raise sexuals in peripheric nest chambers to reduce intracolonial conflicts. The high genetic differentiation recovered from the mtDNA haplotypes, together with the significant correlation of such to geographic distance, and presence of new nuclear alleles between areas (valleys) suggest long-term historical isolation between these regions, indicative of limited dispersal at the regional scale. Our findings on the ecological, social and population structure of this species increases our understanding of the patterns and processes involved under independent colony foundation.

 

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Quid Pro Quo: A Mechanism for Fair Collaboration in Networked Systems

Quid Pro Quo: A Mechanism for Fair Collaboration in Networked Systems | Social Foraging | Scoop.it

Collaboration may be understood as the execution of coordinated tasks (in the most general sense) by groups of users, who cooperate for achieving a common goal. Collaboration is a fundamental assumption and requirement for the correct operation of many communication systems. The main challenge when creating collaborative systems in a decentralized manner is dealing with the fact that users may behave in selfish ways, trying to obtain the benefits of the tasks but without participating in their execution. In this context, Game Theory has been instrumental to model collaborative systems and the task allocation problem, and to design mechanisms for optimal allocation of tasks. In this paper, we revise the classical assumptions of these models and propose a new approach to this problem. First, we establish a system model based on heterogenous nodes (users, players), and propose a basic distributed mechanism so that, when a new task appears, it is assigned to the most suitable node. The classical technique for compensating a node that executes a task is the use of payments (which in most networks are hard or impossible to implement). Instead, we propose a distributed mechanism for the optimal allocation of tasks without payments. We prove this mechanism to be robust evenevent in the presence of independent selfish or rationally limited players. Additionally, our model is based on very weak assumptions, which makes the proposed mechanisms susceptible to be implemented in networked systems (e.g., the Internet).

 

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Jim Price's curator insight, September 14, 2013 5:45 PM

Well...yes, this sounds really interesting and innovative... and something which might benefit the NHS...but what next...?

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From Birdsong to Human Speech Recognition: Bayesian Inference on a Hierarchy of Nonlinear Dynamical Systems

From Birdsong to Human Speech Recognition: Bayesian Inference on a Hierarchy of Nonlinear Dynamical Systems | Social Foraging | Scoop.it

Our knowledge about the computational mechanisms underlying human learning and recognition of sound sequences, especially speech, is still very limited. One difficulty in deciphering the exact means by which humans recognize speech is that there are scarce experimental findings at a neuronal, microscopic level. Here, we show that our neuronal-computational understanding of speech learning and recognition may be vastly improved by looking at an animal model, i.e., the songbird, which faces the same challenge as humans: to learn and decode complex auditory input, in an online fashion. Motivated by striking similarities between the human and songbird neural recognition systems at the macroscopic level, we assumed that the human brain uses the same computational principles at a microscopic level and translated a birdsong model into a novel human sound learning and recognition model with an emphasis on speech. We show that the resulting Bayesian model with a hierarchy of nonlinear dynamical systems can learn speech samples such as words rapidly and recognize them robustly, even in adverse conditions. In addition, we show that recognition can be performed even when words are spoken by different speakers and with different accents—an everyday situation in which current state-of-the-art speech recognition models often fail. The model can also be used to qualitatively explain behavioral data on human speech learning and derive predictions for future experiments.

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Disney develops 'magical' device to make fingertips sing

Disney develops 'magical' device to make fingertips sing | Social Foraging | Scoop.it

Disney has developed a device to transmit sound through the human body.

 

The Ishin-Den-Shin technology uses a standard microphone to record audio and then converts it into an inaudible signal transmitted through the body of the person holding the microphone.

 

When they touch someone's earlobe, an organic speaker is formed and the sound becomes audible, effectively whispering a message into that person's ear.

 

The sound can be passed from person to person using any physical contact.

The technology, which was developed at Disney Research in Pittsburgh, received an honorary mention at this week's Ars Electronica Festival in Linz, Austria.

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BrainHack 2013 | Opportunities in brain exploration.

BrainHack 2013 | Opportunities in brain exploration. | Social Foraging | Scoop.it

The 2013 Brainhack will be held from October 23-26, 2013 at the Centre International d’Études Pédagogiques, Sèvres (just outside of Paris). Brainhack 2013 is a unique event with the goals of fostering interdisciplinary collaboration and open neuroscience. The structure builds from the concepts of an unconference and hackathon. Participants interested in neuroimaging from any discipline are welcome. Ideal participants span in range from graduate students to professors across any disciplines willing to contribute (e.g., mathematics, computer science, engineering, neuroscience, psychology, psychiatry, neurology, medicine, art, etc…).

 

October 23-26, 2013

Centre International d’Études Pédagogiques, Sèvres, France

More information : www.brainhack.org


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How to dodge & weave past research exaggeration

How to dodge & weave past research exaggeration | Social Foraging | Scoop.it

Yesterday’s uplifting emphasis at the quadrennial medical editors’ scientific meeting was bad research (“Bad research rising”). This morning’s motivational agenda focused on measuring some of the main techniques for jazzing up research results.

 

It started with making research look more independent by not declaring authors’ commercial conflicts of interest (COI). Kristine Rasmussen told us that in Denmark, doctors have to apply for permission to collaborate with industry. That enabled Rasmussen and her colleagues to study whether or not doctors who did clinical trials were declaring their commercial relationships with drug manufacturers.

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How Swarm Intelligence is Driven by Social Media

The Wisdom of Crowds or Collective Intelligence is an emerging trend within meetings that is being driven by audiences and the application of social media. This is altering the fundamentals of meeting design and adding new demands upon speakers who are increasingly moderating collective input being delivered via these channels.

 

But the use of technologies by delegates is raising important questions over whether they add to, or detract from, the quality of meeting input and output. Vienna Convention Bureau chief Christian Mutschlechner broke away from his faculty duties at the recent European Summer School in Istanbul to shed light upon the Wisdom of Crowds on future meetings architecture and design. The JMIC Unity Award winner also explains that this form of collective intelligence will be put on public trial at the forthcoming "Access" event by its "Active Academy" on the trade show floor of Austria's meetings and business events showcase from 7-8th October.

 

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Big Data, Privacy, and Trusted Web: What Needs to Be Done

Big Data, Privacy, and Trusted Web: What Needs to Be Done | Social Foraging | Scoop.it
This perspective paper discusses challenges and risks of the information age, and the implications for the information and communication technologies that need to be built and operated. It addresses ethical and policy issues related with Big Data and how procedures for privacy-preserving data analyses can be established. It further proposes a concept for a future, self-organising and trusted Web and discusses recommended legal regulations as well as the infrastructure and institutions needed.

 

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Most Influential Emotions on Social Networks Revealed (Anger > Joy)

Most Influential Emotions on Social Networks Revealed (Anger > Joy) | Social Foraging | Scoop.it

Anger spreads faster and more broadly than joy, say computer scientists who have analysed sentiment on the Chinese Twitter-like service Weibo.

 

One well-known feature of social networks is that similar people tend to attract each other: birds of a feather flock together.

 

So an interesting question is whether these similarities cause people to behave in the same way online, whether it might lead to flocking or herding behaviour, for example.

 

Today, we get an interesting insight into this phenomena thanks to the work of Rui Fan and pals at Beihang University in China. These guys have compared the way that tweets labelled with specific emotions influence other people on the network.

 

And their conclusion is surprising. They say the results clearly show that anger is more influential than other emotions such as joy or sadness, a finding that could have significant implications for our understanding of the way information spreads through social networks.

 

These guys got their data from Weibo, a Twitter-like service that has become hugely popular in China. In just four years, it has attracted more than 500 million users who post around 100 million messages a day.

 

Research Paper: http://arxiv.org/abs/1309.2402 (Anger is More Influential Than Joy: Sentiment Correlation in Weibo Rui Fan, Jichang Zhao, Yan Chen, Ke Xu)

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Abrupt rise of new machine ecology beyond human response time

Society's techno-social systems are becoming ever faster and more computer-orientated. However, far from simply generating faster versions of existing behaviour, we show that this speed-up can generate a new behavioural regime as humans lose the ability to intervene in real time. Analyzing millisecond-scale data for the world's largest and most powerful techno-social system, the global financial market, we uncover an abrupt transition to a new all-machine phase characterized by large numbers of subsecond extreme events. The proliferation of these subsecond events shows an intriguing correlation with the onset of the system-wide financial collapse in 2008. Our findings are consistent with an emerging ecology of competitive machines featuring ‘crowds’ of predatory algorithms, and highlight the need for a new scientific theory of subsecond financial phenomena.

 

Abrupt rise of new machine ecology beyond human response time
Neil Johnson Guannan Zhao Eric Hunsader Hong Qi Nicholas Johnson Jing Meng Brian Tivnan

Scientific Reports 3, Article number: 2627 http://dx.doi.org/10.1038/srep02627


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kalexandera's curator insight, September 21, 2013 5:26 PM

This is proof that speed and complexity will syncronize creating patterns. This was proven earlier by a simple on/off experiment with lights. simple rules create complex patterns - you don't need conscious intervention. The impact of these patterns, however are sourced by life......

 

Fab GOUX-BAUDIMENT's curator insight, September 23, 2013 8:20 AM

here we are... at the dawn of a human-machine competition?

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ReaDDy - A Software for Particle-Based Reaction-Diffusion Dynamics in Crowded Cellular Environments

ReaDDy - A Software for Particle-Based Reaction-Diffusion Dynamics in Crowded Cellular Environments | Social Foraging | Scoop.it

We introduce the software package ReaDDy for simulation of detailed spatiotemporal mechanisms of dynamical processes in the cell, based on reaction-diffusion dynamics with particle resolution. In contrast to other particle-based reaction kinetics programs, ReaDDy supports particle interaction potentials. This permits effects such as space exclusion, molecular crowding and aggregation to be modeled. The biomolecules simulated can be represented as a sphere, or as a more complex geometry such as a domain structure or polymer chain. ReaDDy bridges the gap between small-scale but highly detailed molecular dynamics or Brownian dynamics simulations and large-scale but little-detailed reaction kinetics simulations. ReaDDy has a modular design that enables the exchange of the computing core by efficient platform-specific implementations or dynamical models that are different from Brownian dynamics.

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Weber’s Law, the Magnitude Effect and Discrimination of Sugar Concentrations in Nectar-Feeding Animals

Weber’s Law, the Magnitude Effect and Discrimination of Sugar Concentrations in Nectar-Feeding Animals | Social Foraging | Scoop.it

Weber’s law quantifies the perception of difference between stimuli. For instance, it can explain why we are less likely to detect the removal of three nuts from a bowl if the bowl is full than if it is nearly empty. This is an example of the magnitude effect – the phenomenon that the subjective perception of a linear difference between a pair of stimuli progressively diminishes when the average magnitude of the stimuli increases. Although discrimination performances of both human and animal subjects in various sensory modalities exhibit the magnitude effect, results sometimes systematically deviate from the quantitative predictions based on Weber’s law. An attempt to reformulate the law to better fit data from acoustic discrimination tasks has been dubbed the “near-miss to Weber’s law”. Here, we tested the gustatory discrimination performance of nectar-feeding bats (Glossophaga soricina), in order to investigate whether the original version of Weber’s law accurately predicts choice behavior in a two-alternative forced choice task. As expected, bats either preferred the sweeter of the two options or showed no preference. In 4 out of 6 bats the near-miss to Weber’s law provided a better fit and Weber’s law underestimated the magnitude effect. In order to test the generality of this observation in nectar-feeders, we reviewed previously published data on bats, hummingbirds, honeybees, and bumblebees. In all groups of animals the near-miss to Weber’s law provided better fits than Weber’s law. Furthermore, whereas the magnitude effect was stronger than predicted by Weber’s law in vertebrates, it was weaker than predicted in insects. Thus nectar-feeding vertebrates and insects seem to differ in how their choice behavior changes as sugar concentration is increased. We discuss the ecological and evolutionary implications of the observed patterns of sugar concentration discrimination.

 

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Children's Computation of Complex Linguistic Forms: A Study of Frequency and Imageability Effects

This study investigates the storage vs. composition of inflected forms in typically-developing children. Children aged 8–12 were tested on the production of regular and irregular past-tense forms. Storage (vs. composition) was examined by probing for past-tense frequency effects and imageability effects – both of which are diagnostic tests for storage – while controlling for a number of confounding factors. We also examined sex as a factor. Irregular inflected forms, which must depend on stored representations, always showed evidence of storage (frequency and/or imageability effects), not only across all children, but also separately in both sexes. In contrast, for regular forms, which could be either stored or composed, only girls showed evidence of storage. This pattern is similar to that found in previously-acquired adult data from the same task, with the notable exception that development affects which factors influence the storage of regulars in females: imageability plays a larger role in girls, and frequency in women. Overall, the results suggest that irregular inflected forms are always stored (in children and adults, and in both sexes), whereas regulars can be either composed or stored, with their storage a function of various item- and subject-level factors.

 

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The Structure of Spatial Networks and Communities in Bicycle Sharing Systems

The Structure of Spatial Networks and Communities in Bicycle Sharing Systems | Social Foraging | Scoop.it

Bicycle sharing systems exist in hundreds of cities around the world, with the aim of providing a form of public transport with the associated health and environmental benefits of cycling without the burden of private ownership and maintenance. Five cities have provided research data on the journeys (start and end time and location) taking place in their bicycle sharing system. In this paper, we employ visualization, descriptive statistics and spatial and network analysis tools to explore system usage in these cities, using techniques to investigate features specific to the unique geographies of each, and uncovering similarities between different systems. Journey displacement analysis demonstrates similar journey distances across the cities sampled, and the (out)strength rank curve for the top 50 stands in each city displays a similar scaling law for each. Community detection in the derived network can identify local pockets of use, and spatial network corrections provide the opportunity for insight above and beyond proximity/popularity correlations predicted by simple spatial interaction models.

 

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Learning Contrast-Invariant Cancellation of Redundant Signals in Neural Systems

Learning Contrast-Invariant Cancellation of Redundant Signals in Neural Systems | Social Foraging | Scoop.it

Cancellation of redundant information is a highly desirable feature of sensory systems, since it would potentially lead to a more efficient detection of novel information. However, biologically plausible mechanisms responsible for such selective cancellation, and especially those robust to realistic variations in the intensity of the redundant signals, are mostly unknown. In this work, we study, via in vivo experimental recordings and computational models, the behavior of a cerebellar-like circuit in the weakly electric fish which is known to perform cancellation of redundant stimuli. We experimentally observe contrast invariance in the cancellation of spatially and temporally redundant stimuli in such a system. Our model, which incorporates heterogeneously-delayed feedback, bursting dynamics and burst-induced STDP, is in agreement with our in vivo observations. In addition, the model gives insight on the activity of granule cells and parallel fibers involved in the feedback pathway, and provides a strong prediction on the parallel fiber potentiation time scale. Finally, our model predicts the existence of an optimal learning contrast around 15% contrast levels, which are commonly experienced by interacting fish.

 

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Absurd Creature of the Week: The Zombie Ant and the Fungus That Controls Its Mind

Absurd Creature of the Week: The Zombie Ant and the Fungus That Controls Its Mind | Social Foraging | Scoop.it

The zombie is a simple creature with simple tastes, enjoying leisurely walks on the beach, dining out with hordes of its friends, and every now and then having a good tumble down a flight of stairs. It behaves this way because the pathogen that has infected it doesn’t require complex behaviors in order to replicate — it commands a hungry, nearly indestructible vessel that can walk it right up to its next potential host.

 

But on our planet there exist zombified ants that undergo a decidedly more complex, and more disturbing, transformation at the hands of highly sophisticated parasitic fungi that assume control of the insects’ minds. What ensues between a host and a parasite with no brain of its own is a battle that is far stranger and far more methodical than anything ever dreamed up by Hollywood. (The zombifying fungus that attacks humans in the videogame The Last of Us comes close, but its real-life counterpart is much, much weirder. And you don’t have to pay 60 bucks to see it, which is nice.)

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10 Tips for Sentiment Analysis projects

10 Tips for Sentiment Analysis projects | Social Foraging | Scoop.it

The Sentiment Analysis is an application of Natural Language Processing which targets on the identification of the sentiment (positive vs negative vs neutral), the subjectivity (objective vs subjective) and the emotional states of the document.

During my thesis, I had the opportunity learn about new machine learning techniques but also bumped into some interesting and non-obvious matters. In this article I discuss the things that I found most interesting while working on the Sentiment Analysis project and I provide some tips that you should have in mind while working on similar Natural Language Processing problems.

- See more at: http://blog.datumbox.com/10-tips-for-sentiment-analysis-projects/#sthash.MwhsoFBm.dpuf
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Complexity of evolutionary equilibria in static fitness landscapes

A fitness landscape is a genetic space -- with two genotypes adjacent if they differ in a single locus -- and a fitness function. Evolutionary dynamics produce a flow on this landscape from lower fitness to higher; reaching equilibrium only if a local fitness peak is found. I use computational complexity to question the common assumption that evolution on static fitness landscapes can quickly reach a local fitness peak. I do this by showing that the popular NK model of rugged fitness landscapes is PLS-complete for K >= 2; the reduction from Weighted 2SAT is a bijection on adaptive walks, so there are NK fitness landscapes where every adaptive path from some vertices is of exponential length. Alternatively -- under the standard complexity theoretic assumption that there are problems in PLS not solvable in polynomial time -- this means that there are no evolutionary dynamics (known, or to be discovered, and not necessarily following adaptive paths) that can converge to a local fitness peak on all NK landscapes with K = 2. Applying results from the analysis of simplex algorithms, I show that there exist single-peaked landscapes with no reciprocal sign epistasis where the expected length of an adaptive path following strong selection weak mutation dynamics is $e^{O(n^{1/3})}$ even though an adaptive path to the optimum of length less than n is available from every vertex. The technical results are written to be accessible to mathematical biologists without a computer science background, and the biological literature is summarized for the convenience of non-biologists with the aim to open a constructive dialogue between the two disciplines.

 

Complexity of evolutionary equilibria in static fitness landscapes
Artem Kaznatcheev

http://arxiv.org/abs/1308.5094


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