Social Foraging
67.9K views | +0 today
Follow
Social Foraging
Dynamics of Social Interaction
Curated by Ashish Umre
Your new post is loading...
Your new post is loading...
Rescooped by Ashish Umre from Amazing Science
Scoop.it!

Faster than any human can: Lego Cubestormer 3 robot solves Rubik's Cube in 3.253 seconds

Faster than any human can: Lego Cubestormer 3 robot solves Rubik's Cube in 3.253 seconds | Social Foraging | Scoop.it

The ARM-Powered CUBESTORMER 3 robot has smashed the Guinness World Record for solving a Rubik's cube, recording a time of 3.253 seconds at the Big Bang Fair in Birmingham, UK.

The robot employs an ARM-powered Samsung® Galaxy S4 smartphone powered by a Samsung Exynos 5 Octa application processor to analyze the cube and instruct four robotic hands to do the manipulations. ARM9™ processors also power the eight LEGO® MINDSTORMS® EV3 bricks which perform the motor sequencing and control.

CUBESTORMER 3 was designed, built and programmed by Mike Dobson and David Gilday, creators respectively of CubeStormerhttp://youtu.be/eaRcWB3jwMo and Android Speedcuberhttp://youtu.be/ylFb4pqAUd8 and more recently, co-creators of CubeStormer II http://www.youtube.com/watch?v=_d0Lfk...

The custom app developed for the smartphone uses the phone's camera to capture images of each face of the Rubik's Cube which it processes to determine the scrambled colors.The solution is found using an advanced two-phase algorithm that was originally developed for Speedcuber and then enhanced to make effective use of the dual-core ARM Cortex®-A9 based processor in a Samsung Galaxy SII smartphone powered by an Exynos 5 Dual application processor used in CubeStormer II. Further optimizations were made to take advantage of the eight-core big.LITTLE™ processor configuration in the Exynos 5 Octa application processor featuring four Cortex-A15 and four Cortex-A7 processors in the Galaxy S4.

Human speedcubers' solve times only include the physical manipulation of the cube and do not include some time which is allowed to "inspect" the cube beforehand. Times recorded by CUBESTORMER 3 are for the total solve including: image capture, software solution calculation and physical solve.


Via Dr. Stefan Gruenwald
more...
The Science & Education team's curator insight, March 24, 2014 8:32 PM

When I was at uni, the other maths geek from my school, Leanne, was a state champion at Rubix, so I feel a certain affinity with Rubix geekdom and this is the ultimate. It was good to have a computer to beat us at Chess (although this has not yet been accomplished with Go) but Rubix, being both mechanical and computational is even better.

Scooped by Ashish Umre
Scoop.it!

How Machines Are Advancing at an Exponential Rate

How Machines Are Advancing at an Exponential Rate | Social Foraging | Scoop.it
With The Second Machine Age, Erik Brynjolfsson and Andrew McAfee explore the future for technology.

 

 

The Second Machine Age debuted at number nine this month on The New York Times’ hardcover non-fiction bestseller list.

 

But it should surprise no one that people are reading. The book’s subject—how machines and computers are advancing at an exponential rate and what that means for society and the American economy—is all encompassing. Its findings are relevant not just for business, but also for government, workers, and families.

more...
No comment yet.
Scooped by Ashish Umre
Scoop.it!

The Curious Nature of Sharing Cascades on Facebook

The Curious Nature of Sharing Cascades on Facebook | Social Foraging | Scoop.it
Most content on Facebook is shared a few times but some can be shared millions of times. Now computer scientists are beginning to understand the difference.

 

One of the defining features of social content is the way pictures, video and text is shared among many users. Inevitably, some content becomes more popular than others and this leads to cascades in which the number of reshares can be huge. While most pieces of media have only a few shares, some are reshared many millions of times.

 

So there is much interest in finding out how to predict something that is likely to be popular compared to something that is not. On the face of it, it’s easy to think that predicting the popularity of content is almost impossible. That’s because it depends on so many factors that are difficult to measure, such as the nature of the content and the connectivity of the people who see it.

more...
No comment yet.
Scooped by Ashish Umre
Scoop.it!

Ninja Blocks

Ninja Blocks | Social Foraging | Scoop.it

The Ninja Blocks Platform makes connecting so called “things” to the internet and each other easy through open source hardware, software and an API service.

 

Ninja Blocks are tiny open source computers that can sense and react to their environment. They support RF out of the box and are designed to be extended to support everything.

 

The Ninja Blocks API makes it simple to create apps (webapps, widgets, phone apps) that interact with a users devices. The block software “wraps” proprietary devices and offers their features through a RESTful API. Ninja Blocks address the critical element of interoperability - addressing (how do you identify a device), authentication (are you allowed to talk to a device) and protocol (how do you control a device).

 

The Ninja Blocks mission is to enable real interoperability in the fledgling world of the Internet of Things.

more...
No comment yet.
Scooped by Ashish Umre
Scoop.it!

How Virtual Gaming Worlds Are Revealing the Nature of Human Hierarchies

How Virtual Gaming Worlds Are Revealing the Nature of Human Hierarchies | Social Foraging | Scoop.it

The way players form into groups in online games reveals that hierarchies are an inevitable product of the human condition, say complexity scientists.


One of the goals of anthropology is to understand the way that humans interact to form groups. Indeed, anthropologists have long known that human societies are highly structured.


But exactly what kinds of structures form and to what extent these groupings depend on the environment is still the subject of much debate. So an interesting question is whether humans form the same kinds of structures in online worlds as they do in real life.

 

more...
No comment yet.
Scooped by Ashish Umre
Scoop.it!

We Finally Know Why You Can Sustain a Conversation in a Noisy Bar

We Finally Know Why You Can Sustain a Conversation in a Noisy Bar | Social Foraging | Scoop.it

Normally, human ears are incredibly good at focusing on sounds of specific frequencies and simultaneously filtering out the rest of the noise — your drinking buddy’s voice in a crowded bar, for example. This is why you can have conversations in places with a wild and crazy soundscape. If we paid attention to all the noises all the time, there would be no way to distinguish between your friend’s on-the-spot beer review and the clamor of vapid background conversations.

 

As we age, though, this ability to focus on particular frequencies wanes. Which is why, if you’re like me and enjoy hanging out with your parents in bars, you find yourself yelling more loudly as the years go on.

 

more...
No comment yet.
Rescooped by Ashish Umre from Amazing Science
Scoop.it!

CODE_n: Data Visualizations in Grande Scale Shown at CeBit 2014

CODE_n: Data Visualizations in Grande Scale Shown at CeBit 2014 | Social Foraging | Scoop.it

I guess that CODE_n [http://kramweisshaar.com], developed by design agency Kram/Weisshaar, is best appreciated when perceived in the flesh, that is at the Hannover Fairgrounds during CeBit 2014 in Hannover, Germany.

 

CODE_n consists of more than 3.000 square meters (approx. 33,000 ft2) of ink-jet printed textile membranes, stretching more than 260 meters of floor-to-ceiling tera-pixel graphics. The 12.5 terapixel, 90-meter long wall-like canopy titled "Retrospective Trending", shows over 400 lexical frequency timelines ranging from the years 1800 to 2008, each generated using Google's Ngram tool. The hundreds of search terms relate to ethnographic themes of politics, economics, engineering, science, technology, mathematics, and philosophy, resulting in the output of historical trajectories of word usage over time.


The 6.2 terapixel "Hydrosphere Hyperwall" is a visualization of the global ocean as dynamic pathways, polychrome swathes of sea climate, data-collecting swarms of mini robots and sea animals, as well as plumes of narrow current systems. NASA's ECCO2 maps were interwoven with directional arrows that specify wind direction and data vectors that represent buoys, cargo floats, research ships, wave gliders, sea creatures and research stations.

 

Finally, the 6.6 terapixel "Human Connectome" is a morphological map of the human brain. Consisting of several million multi-coloured fibre bundles and white matter tracts that were captured by diffusion-MRIs, the structural descriptions of the human mind were generated at 40 times the scale of the human body. The 3D map of human neural connections visualizes brain dynamics on an ultra-macro scale as well as the infinitesimal cell-scale.


Via Dr. Stefan Gruenwald
more...
No comment yet.
Scooped by Ashish Umre
Scoop.it!

Sugata Mitra Opens ‘School in the Cloud’ in Sundarbans

Sugata Mitra Opens ‘School in the Cloud’ in Sundarbans | Social Foraging | Scoop.it

Noted educationist and 2013 TED Prize winner Sugata Mitrahas opened his first ‘School in the Cloud’ project in India at Korakati, a small village in the Sundarbans.

 

About 800 miles west of Kolkata, the village located in a mangrove swamp, is Sugata Mitra’s first independent, solar-powered learning platform with a group of teachers who are available over Skype from a remote location to help mentor the children as they explore information.

 

Located at a difficult to reach village, the school has equipped itself with a 40ft bamboo tower receiver in order to get the necessary data bandwidth.

 

The center is the fourth of the 7 new Self Organised Learning (SOLEs) locations to open as part of  Mitra’s $1m TED Prize-funded project. While the other SOLEs are attached to schools, the one at Korakati is the first to be a stand alone.

 

more...
No comment yet.
Scooped by Ashish Umre
Scoop.it!

How Do You Say ‘Hello’? Personality Impressions from Brief Novel Voices

How Do You Say ‘Hello’? Personality Impressions from Brief Novel Voices | Social Foraging | Scoop.it

On hearing a novel voice, listeners readily form personality impressions of that speaker. Accurate or not, these impressions are known to affect subsequent interactions; yet the underlying psychological and acoustical bases remain poorly understood. Furthermore, hitherto studies have focussed on extended speech as opposed to analysing the instantaneous impressions we obtain from first experience. In this paper, through a mass online rating experiment, 320 participants rated 64 sub-second vocal utterances of the word ‘hello’ on one of 10 personality traits. We show that: (1) personality judgements of brief utterances from unfamiliar speakers are consistent across listeners; (2) a two-dimensional ‘social voice space’ with axes mapping Valence (Trust, Likeability) and Dominance, each driven by differing combinations of vocal acoustics, adequately summarises ratings in both male and female voices; and (3) a positive combination of Valence and Dominance results in increased perceived male vocal Attractiveness, whereas perceived female vocal Attractiveness is largely controlled by increasing Valence. Results are discussed in relation to the rapid evaluation of personality and, in turn, the intent of others, as being driven by survival mechanisms via approach or avoidance behaviours. These findings provide empirical bases for predicting personality impressions from acoustical analyses of short utterances and for generating desired personality impressions in artificial voices.

 

more...
No comment yet.
Scooped by Ashish Umre
Scoop.it!

Overlapping Neural Systems Represent Cognitive Effort and Reward Anticipation

Overlapping Neural Systems Represent Cognitive Effort and Reward Anticipation | Social Foraging | Scoop.it

Anticipating a potential benefit and how difficult it will be to obtain it are valuable skills in a constantly changing environment. In the human brain, the anticipation of reward is encoded by the Anterior Cingulate Cortex (ACC) and Striatum. Naturally, potential rewards have an incentive quality, resulting in a motivational effect improving performance. Recently it has been proposed that an upcoming task requiring effort induces a similar anticipation mechanism as reward, relying on the same cortico-limbic network. However, this overlapping anticipatory activity for reward and effort has only been investigated in a perceptual task. Whether this generalizes to high-level cognitive tasks remains to be investigated. To this end, an fMRI experiment was designed to investigate anticipation of reward and effort in cognitive tasks. A mental arithmetic task was implemented, manipulating effort (difficulty), reward, and delay in reward delivery to control for temporal confounds. The goal was to test for the motivational effect induced by the expectation of bigger reward and higher effort. The results showed that the activation elicited by an upcoming difficult task overlapped with higher reward prospect in the ACC and in the striatum, thus highlighting a pivotal role of this circuit in sustaining motivated behavior.

 

more...
No comment yet.
Scooped by Ashish Umre
Scoop.it!

The Voice of Emotion across Species: How Do Human Listeners Recognize Animals' Affective States?

The Voice of Emotion across Species: How Do Human Listeners Recognize Animals' Affective States? | Social Foraging | Scoop.it

Voice-induced cross-taxa emotional recognition is the ability to understand the emotional state of another species based on its voice. In the past, induced affective states, experience-dependent higher cognitive processes or cross-taxa universal acoustic coding and processing mechanisms have been discussed to underlie this ability in humans. The present study sets out to distinguish the influence of familiarity and phylogeny on voice-induced cross-taxa emotional perception in humans. For the first time, two perspectives are taken into account: the self- (i.e. emotional valence induced in the listener) versus the others-perspective (i.e. correct recognition of the emotional valence of the recording context). Twenty-eight male participants listened to 192 vocalizations of four different species (human infant, dog, chimpanzee and tree shrew). Stimuli were recorded either in an agonistic (negative emotional valence) or affiliative (positive emotional valence) context. Participants rated the emotional valence of the stimuli adopting self- and others-perspective by using a 5-point version of the Self-Assessment Manikin (SAM). Familiarity was assessed based on subjective rating, objective labelling of the respective stimuli and interaction time with the respective species. Participants reliably recognized the emotional valence of human voices, whereas the results for animal voices were mixed. The correct classification of animal voices depended on the listener's familiarity with the species and the call type/recording context, whereas there was less influence of induced emotional states and phylogeny. Our results provide first evidence that explicit voice-induced cross-taxa emotional recognition in humans is shaped more by experience-dependent cognitive mechanisms than by induced affective states or cross-taxa universal acoustic coding and processing mechanisms.

 

more...
No comment yet.
Scooped by Ashish Umre
Scoop.it!

Collaboration Networks from a Large CV Database: Dynamics, Topology and Bonus Impact

Collaboration Networks from a Large CV Database: Dynamics, Topology and Bonus Impact | Social Foraging | Scoop.it

Understanding the dynamics of research production and collaboration may reveal better strategies for scientific careers, academic institutions, and funding agencies. Here we propose the use of a large and multidisciplinary database of scientific curricula in Brazil, namely, the Lattes Platform, to study patterns of scientific production and collaboration. Detailed information about publications and researchers is available in this database. Individual curricula are submitted by the researchers themselves so that coauthorship is unambiguous. Researchers can be evaluated by scientific productivity, geographical location and field of expertise. Our results show that the collaboration network is growing exponentially for the last three decades, with a distribution of number of collaborators per researcher that approaches a power-law as the network gets older. Moreover, both the distributions of number of collaborators and production per researcher obey power-law behaviors, regardless of the geographical location or field, suggesting that the same universal mechanism might be responsible for network growth and productivity. We also show that the collaboration network under investigation displays a typical assortative mixing behavior, where teeming researchers (i.e., with high degree) tend to collaborate with others alike.

more...
No comment yet.
Scooped by Ashish Umre
Scoop.it!

Contextual effect of positive intergroup contact on outgroup prejudice

Contextual effect of positive intergroup contact on outgroup prejudice | Social Foraging | Scoop.it

Although mixed social environments can provoke conflict, where this diversity promotes positive intergroup contact, prejudice is reduced. Seven multilevel studies demonstrate that the benefits of intergroup contact are broader than previously thought. Contact not only changes attitudes for individuals experiencing direct positive intergroup contact, their attitudes are also influenced by the behavior (and norms) of fellow ingroup members in their social context. Even individuals experiencing no direct, face-to-face intergroup contact can benefit from living in mixed settings where fellow ingroup members do engage in such contact. Two longitudinal studies rule out selection bias as an explanation for these findings on the contextual level. Prejudice is a function not only of whom you interact with, but also of where you live.

 

We assessed evidence for a contextual effect of positive intergroup contact, whereby the effect of intergroup contact between social contexts (the between-level effect) on outgroup prejudice is greater than the effect of individual-level contact within contexts (the within-level effect). Across seven large-scale surveys (five cross-sectional and two longitudinal), using multilevel analyses, we found a reliable contextual effect. This effect was found in multiple countries, operationalizing context at multiple levels (regions, districts, and neighborhoods), and with and without controlling for a range of demographic and context variables. In four studies (three cross-sectional and one longitudinal) we showed that the association between context-level contact and prejudice was largely mediated by more tolerant norms. In social contexts where positive contact with outgroups was more commonplace, norms supported such positive interactions between members of different groups. Thus, positive contact reduces prejudice on a macrolevel, whereby people are influenced by the behavior of others in their social context, not merely on a microscale, via individuals’ direct experience of positive contact with outgroup members. These findings reinforce the view that contact has a significant role to play in prejudice reduction, and has great policy potential as a means to improve intergroup relations, because it can simultaneously impact large numbers of people.

more...
No comment yet.
Rescooped by Ashish Umre from Biomimicry
Scoop.it!

Robot Octopus Shows Off New Sculls

Robot Octopus Shows Off New Sculls | Social Foraging | Scoop.it

"Octopi are pro swimmers, thanks (at least in part) to that octet of arms they've got going on. They've adopted a particular swimming gait called sculling, which works great for them, but until they start publishing scientific papers, we're missing out on all of their gait testing data. Roboticists have had to start from scratch, and along the way, they've experimented with some swimming gaits that we've never seen a real octopus try and pull off."


Via Miguel Prazeres
more...
No comment yet.
Scooped by Ashish Umre
Scoop.it!

Facebook Creates Software That Matches Faces Almost as Well as You Do

Facebook Creates Software That Matches Faces Almost as Well as You Do | Social Foraging | Scoop.it
Facebook’s new AI research group reports a major improvement in face-processing software.

 

Asked whether two unfamiliar photos of faces show the same person, a human being will get it right 97.53 percent of the time. New software developed by researchers at Facebook can score 97.25 percent on the same challenge, regardless of variations in lighting or whether the person in the picture is directly facing the camera.

 

That’s a significant advance over previous face-matching software, and it demonstrates the power of a new approach to artificial intelligence known as deep learning, which Facebook and its competitors have bet heavily on in the past year (see “Deep Learning”). This area of AI involves software that uses networks of simulated neurons to learn to recognize patterns in large amounts of data.

 

“You normally don’t see that sort of improvement,” says Yaniv Taigman, a member of Facebook’s AI team, a research group created last year to explore how deep learning might help the company (see “Facebook Launches Advanced AI Effort”). “We closely approach human performance,” says Taigman of the new software. He notes that the error rate has been reduced by more than a quarter relative to earlier software that can take on the same task.

more...
No comment yet.
Scooped by Ashish Umre
Scoop.it!

Invisible: Animals and machines hiding in plain sight

Invisible: Animals and machines hiding in plain sight | Social Foraging | Scoop.it

We used to think there was only one way to stay hidden from trouble – blend into the background. See how nature has taught us a more flamboyant approach.

more...
No comment yet.
Scooped by Ashish Umre
Scoop.it!

Facebook Introduces 'Hack,' the Programming Language Of the Future

Facebook Introduces 'Hack,' the Programming Language Of the Future | Social Foraging | Scoop.it

Facebook engineers Bryan O’Sullivan, Julien Verlaguet, and Alok Menghrajani spent the last few years building a programming language unlike any other.

 

Working alongside a handful of others inside the social networking giant, they fashioned a language that lets programmers build complex websites and other software at great speed while still ensuring that their software code is precisely organized and relatively free of flaws — a combination that few of today’s languages even approach. In typical Facebook fashion, the new language is called Hack, and it already drives almost all of the company’s website — a site that serves more than 1.2 billion people across the globe.

 

“We can say with complete assurance that this has been as battle tested as it can possibly be,” says O’Sullivan, a veteran of iconic tech companies Sun Microsystems and Linden Lab who has long played an important role in a popular language called Haskell.

 

O’Sullivan and company publicly revealed their new language this morning, and at the same time, they “open sourced” it, sharing the technology with the world at large and encouraging others not only to use it, but to help improve it.

 

The software world is littered with programming languages, and new ones appear all the time. But according to some who have used it or who know the past work of those who built it, Hack has a design and a pedigree that immediately set it apart. “If Bryan O’Sullivan built it,” says programming guru David Pollak, who only yesterday heard about the new language, “I would walk across hot coals to use it.”

more...
M. Edward (Ed) Borasky's comment, March 20, 2014 12:49 PM
Sigh ... another syntax and semantics to learn :-(
Scooped by Ashish Umre
Scoop.it!

Data Mining Reveals How Conspiracy Theories Emerge on Facebook

Data Mining Reveals How Conspiracy Theories Emerge on Facebook | Social Foraging | Scoop.it

Some people are more susceptible to conspiracy theories than others, say computational social scientists who have studied how false ideas jump the “credulity barrier” on Facebook.

 

During the Italian elections last year, a post appeared on Facebook that rapidly became viral. The post’s title was this: “Italian Senate voted and accepted (257 in favor and 165 abstentions) a law proposed by Senator Cirenga to provide policy makers with €134 billion Euros to find jobs in the event of electoral defeat”.

 

The post was created on Facebook page known for its satirical content and designed to parody Italian politics. It contains at least four false statements: the senator involved is fictitious, the total number of votes is higher than is possible in Italian politics, the amount of money involved is more than 10% of Italian GDP and the law itself is an invention.

 

The parody struck a chord with disenchanted voters who shared it some 35,000 times in less than a month. Then things quickly became strange.

 

more...
No comment yet.
Rescooped by Ashish Umre from Complex Systems
Scoop.it!

Semantic Weak Signal Tracing

Semantic Weak Signal Tracing | Social Foraging | Scoop.it

The weak signal concept according to Ansoff has the aim to advance strategic early warning. It enables to predict the appearance of events in advance that are relevant for an organization. An example is to predict the appearance of a new and relevant technology for a research organization. Existing approaches detect weak signals based on an environmental scanning procedure that considers textual information from the internet. This is because about 80% of all data in the internet are textual information. The texts are processed by a specific clustering approach where clusters that represent weak signals are identified. In contrast to these related approaches, we propose a new methodology that investigates a sequence of clusters measured at successive points in time. This enables to trace the development of weak signals over time and thus, it enables to identify relevant weak signal developments for organization’s decision making in strategic early warning environment.


Via David Rodrigues
more...
No comment yet.
Scooped by Ashish Umre
Scoop.it!

Flying Donkey Challenge (Drone Delivery): The African Version of Amazon Will Emerge From Nigeria

Flying Donkey Challenge (Drone Delivery): The African Version of Amazon Will Emerge From Nigeria | Social Foraging | Scoop.it

Africa's tech space, which has been defined and accelerated by the mobile phone, is undoubtedly growing as investors scramble toward the continent. Various African countries have leapfrogged fixed-line

Internet because of the ubiquity of cellphones and their networks, and entrepreneurs will likely tackle transportation in a similar way. Why build roads to inaccessible places when the air is a better and increasingly cheaper option?

 

A current initiative that addresses African drone delivery is the Flying Donkey Challenge, a 24-hour race around Mount Kenya where African companies have to deliver and collect 20-kilo payloads as they go. The winner receives a prize of more than $1 million.

 

But while these companies face huge challenges in circumnavigating Mount Kenya in East Africa, it's actually in Nigeria, West Africa, where today’s challenges are almost unfathomable in scope — and, yet, also where future "African Amazons" are likely to emerge.

 

Lagos isn't Nigeria’s capital city, but it is by far the biggest in the country. Depending on which statistics you believe, the city’s population is between 17 and 21 million, with 30,000 people arriving every week from across Africa.

 

Delivery in Lagos is utter chaos. There isn’t a viable postal service in the city — or the country, for that matter — and by all standards the city just shouldn’t work. But it does, and ecommerce companies are proliferating. Some even guarantee delivery of products across the city within 24 hours.

 

“By 2030, one in every six Africans will be Nigerians, and its economy will have the largest GDP on the continent," says Betty Enyonam Kumahor, managing director of Africa for global IT consulting firm ThoughtWorks. "But understanding how to launch an ecommerce business in Nigeria requires an understanding of the ecosystem and country, and other aspects such as the cost of generators and the relative dearth of the talent pool."

 

more...
No comment yet.
Scooped by Ashish Umre
Scoop.it!

Detecting Emotional Contagion in Massive Social Networks

Detecting Emotional Contagion in Massive Social Networks | Social Foraging | Scoop.it

Happiness and other emotions spread between people in direct contact, but it is unclear whether massive online social networks also contribute to this spread. Here, we elaborate a novel method for measuring the contagion of emotional expression. With data from millions of Facebook users, we show that rainfall directly influences the emotional content of their status messages, and it also affects the status messages of friends in other cities who are not experiencing rainfall. For every one person affected directly, rainfall alters the emotional expression of about one to two other people, suggesting that online social networks may magnify the intensity of global emotional synchrony.

more...
No comment yet.
Scooped by Ashish Umre
Scoop.it!

The Use of Weighted Graphs for Large-Scale Genome Analysis

The Use of Weighted Graphs for Large-Scale Genome Analysis | Social Foraging | Scoop.it

There is an acute need for better tools to extract knowledge from the growing flood of sequence data. For example, thousands of complete genomes have been sequenced, and their metabolic networks inferred. Such data should enable a better understanding of evolution. However, most existing network analysis methods are based on pair-wise comparisons, and these do not scale to thousands of genomes. Here we propose the use of weighted graphs as a data structure to enable large-scale phylogenetic analysis of networks. We have developed three types of weighted graph for enzymes: taxonomic (these summarize phylogenetic importance), isoenzymatic (these summarize enzymatic variety/redundancy), and sequence-similarity (these summarize sequence conservation); and we applied these types of weighted graph to survey prokaryotic metabolism. To demonstrate the utility of this approach we have compared and contrasted the large-scale evolution of metabolism in Archaea and Eubacteria. Our results provide evidence for limits to the contingency of evolution.

more...
No comment yet.
Scooped by Ashish Umre
Scoop.it!

Very Similar Spacing-Effect Patterns in Very Different Learning/Practice Domains

Very Similar Spacing-Effect Patterns in Very Different Learning/Practice Domains | Social Foraging | Scoop.it

Temporally distributed (“spaced”) learning can be twice as efficient as massed learning. This “spacing effect” occurs with a broad spectrum of learning materials, with humans of different ages, with non-human vertebrates and also invertebrates. This indicates, that very basic learning mechanisms are at work (“generality”). Although most studies so far focused on very narrow spacing interval ranges, there is some evidence for a non-monotonic behavior of this “spacing effect” (“nonlinearity”) with optimal spacing intervals at different time scales. In the current study we focused both the nonlinearity aspect by using a broad range of spacing intervals and the generality aspect by using very different learning/practice domains: Participants learned German-Japanese word pairs and performed visual acuity tests. For each of six groups we used a different spacing interval between learning/practice units from 7 min to 24 h in logarithmic steps. Memory retention was studied in three consecutive final tests, one, seven and 28 days after the final learning unit. For both the vocabulary learning and visual acuity performance we found a highly significant effect of the factor spacing interval on the final test performance. In the 12 h-spacing-group about 85% of the learned words stayed in memory and nearly all of the visual acuity gain was preserved. In the 24 h-spacing-group, in contrast, only about 33% of the learned words were retained and the visual acuity gain dropped to zero. The very similar patterns of results from the two very different learning/practice domains point to similar underlying mechanisms. Further, our results indicate spacing in the range of 12 hours as optimal. A second peak may be around a spacing interval of 20 min but here the data are less clear. We discuss relations between our results and basic learning at the neuronal level.

more...
No comment yet.
Scooped by Ashish Umre
Scoop.it!

Gravity Effects on Information Filtering and Network Evolving

Gravity Effects on Information Filtering and Network Evolving | Social Foraging | Scoop.it

In this paper, based on the gravity principle of classical physics, we propose a tunable gravity-based model, which considers tag usage pattern to weigh both the mass and distance of network nodes. We then apply this model in solving the problems of information filtering and network evolving. Experimental results on two real-world data sets, Del.icio.us and MovieLens, show that it can not only enhance the algorithmic performance, but can also better characterize the properties of real networks. This work may shed some light on the in-depth understanding of the effect of gravity model.

 

more...
No comment yet.
Scooped by Ashish Umre
Scoop.it!

Combinatorial quorum sensing allows bacteria to resolve their social and physical environment

Combinatorial quorum sensing allows bacteria to resolve their social and physical environment | Social Foraging | Scoop.it

Many bacterial species engage in a form of cell–cell communication known as quorum sensing (QS). Despite great progress in unravelling the molecular mechanisms of QS, controversy remains over its functional role. There is disagreement over whether QS surveys bacterial cell density or rather environmental properties like diffusion or flow, and moreover there is no consensus on why many bacteria use multiple signal molecules. We develop and test a new conceptual framework for bacterial cell–cell communication, demonstrating that bacteria can simultaneously infer both their social (density) and physical (mass-transfer) environment, given combinatorial (nonadditive) responses to multiple signals with distinct half-lives. Our results also show that combinatorial communication is not restricted solely to primates and is computationally achievable in single-celled organisms.

 

Quorum sensing (QS) is a cell–cell communication system that controls gene expression in many bacterial species, mediated by diffusible signal molecules. Although the intracellular regulatory mechanisms of QS are often well-understood, the functional roles of QS remain controversial. In particular, the use of multiple signals by many bacterial species poses a serious challenge to current functional theories. Here, we address this challenge by showing that bacteria can use multiple QS signals to infer both their social (density) and physical (mass-transfer) environment. Analytical and evolutionary simulation models show that the detection of, and response to, complex social/physical contrasts requires multiple signals with distinct half-lives and combinatorial (nonadditive) responses to signal concentrations. We test these predictions using the opportunistic pathogen Pseudomonas aeruginosa and demonstrate significant differences in signal decay between its two primary signal molecules, as well as diverse combinatorial responses to dual-signal inputs. QS is associated with the control of secreted factors, and we show that secretome genes are preferentially controlled by synergistic “AND-gate” responses to multiple signal inputs, ensuring the effective expression of secreted factors in high-density and low mass-transfer environments. Our results support a new functional hypothesis for the use of multiple signals and, more generally, show that bacteria are capable of combinatorial communication.

more...
No comment yet.