Mathematics posts
- December 29, 2010
- 04:44 AM
- 1,804 views
What’s the actual size of your personal social network? Some numbers
by ---a in Bodyspacesociety.eu
In 1992 Robin Dunbar proposed a rough estimate of 150. But the "Dunbar's number" pretty much doubled in 1998, when Peter Killworth suggested a mean personal network size of 290. And in 2010 that number doubled again, as Matthew Salganik came up with 610 personal. So who says 1,200?... Read more »
Bickart, K., Wright, C., Dautoff, R., Dickerson, B., & Barrett, L. (2010) Amygdala volume and social network size in humans. Nature Neuroscience. DOI: 10.1038/nn.2724
Dunbar, R. (1992) Neocortex size as a constraint on group size in primates. Journal of Human Evolution, 22(6), 469-493. DOI: 10.1016/0047-2484(92)90081-J
Killworth, P., Johnsen, E., Bernard, H. R., Shelley, G., & McCarty, C. (1990) Estimating the size of personal networks. Social Networks, 12(4), 289-312. DOI: 10.1016/0378-8733(90)90012-X
McCormick, T., Salganik, M., & Zheng, T. (2010) How Many People Do You Know?: Efficiently Estimating Personal Network Size. Journal of the American Statistical Association, 105(489), 59-70. DOI: 10.1198/jasa.2009.ap08518
- December 26, 2010
- 10:37 AM
- 827 views
Oscar: training data, models, etc
by egonw in Chem-bla-ics
Oscar uses a Maximum Entropy Markov Model (MEMM) based on n-grams. Peter Corbett has written this up (doi:10.1186/1471-2105-9-S11-S4). So, it basically is statistics once more. If you really want a proper bioinformatics education, so do your PhD at a (proteo)chemometrics department.
N-grams are word parts of n characters. For example, the trigrams of acetic acid include ace, cid, tic, eti, and aci. N-grams of length four include acid, etic, and acet. The MEMM assigns weights to these n-grams, a........ Read more »
Corbett, P., & Copestake, A. (2008) Cascaded classifiers for confidence-based chemical named entity recognition. BMC Bioinformatics, 9(Suppl 11). DOI: 10.1186/1471-2105-9-S11-S4
- December 14, 2010
- 07:55 PM
- 614 views
Towards Preventing Alzheimer's Disease: A Mathematical Model
by Michael Long in Phased
A mathematical model suggests that inhibiting the immune response in the brain may be the most effective means of controlling Alzheimer's disease.... Read more »
Puri, I. K., & Li, L. (2010) Mathematical Modeling for the Pathogenesis of Alzheimer's Disease. PLoS ONE, 5(12). DOI: 10.1371/journal.pone.0015176
- December 5, 2010
- 02:00 PM
- 949 views
Acupuncture, some dodgy maths and a cracking review paper
by Lorimer Moseley in BodyInMind
I have a challenge for you. Imagine you’re in ancient China and you’ve had this idea that health and disease hang on the flow of energy through invisible energy pathways called meridians that can be manipulated by applying needles in certain specific points. How do you go about systematically validating this theory? How do you [...]... Read more »
Donald M. Marcus. (2010) Is Acupuncture for Pain a Placebo Treatment? An examination of the evidence. The Rheumatologist. info:/
- December 4, 2010
- 01:34 PM
- 786 views
Psi Skeptics: If Psychologists Find Signs of ESP, Maybe Psychologists Have a Problem
by David Berreby in Mind Matters
Daryl J. Bem's experiments on psi caught the world's attention, as I posted last month, because he used standard psychology-lab methods to gather and analyze his data. Imagine what astronomers might feel if NASA announced that the Hubble space telescope had found evidence for astrology: How do you ...Read More... Read more »
Daryl J. Bem. (2011) Feeling the future: Experimental evidence for anomalous retroactive influences on cognition and affect. Journal of Personality and Social Psychology. info:/10.1037/a0021524
- December 3, 2010
- 07:27 PM
- 1,237 views
Networks in the autistic brain: insights from graph theory
by Jon Brock in Cracking the Enigma
A couple of weeks ago I travelled from Sydney to a conference taking place in San Diego, California. There isn't a direct flight to San Diego so instead I had to fly via Los Angeles. Colleagues coming from Melbourne had an even more convoluted journey - they had to get a connecting flight to Sydney first before they could fly to LA. The point here is that airline routes are determined by economic pressures. There simply aren't enough people wanting to travel from Sydney or Melbourne to San Dieg........ Read more »
Pablo Barttfeld, Bruno Wicker, Sebastián Cukier, Silvana Navarta, Sergio Lew, & Mariano Sigman. (2010) A big-world network in ASD: Dynamical connectivity analysis reflects a deficit in long-range connections and an excess of short-range connections. Neuropsychologia. arXiv: 1007.5471v1
- November 22, 2010
- 01:35 PM
- 1,199 views
The Obesity Paradox Revisited
by Travis Saunders, MSc in Obesity Panacea
As Peter and I discuss frequently here at Obesity Panacea, the relationship between body weight and health is not always as neat and tidy as you might expect (For all the details, check out Peter’s 5-part series on metabolically healthy obesity). A recent paper published in the International Journal of Obesity by Drs DK Childers and David Allison examines a number of these issues, and suggests ways that they may be at least partially resolved.
In the intro to this new paper, the author........ Read more »
Childers, D., & Allison, D. (2010) The ‘obesity paradox’: a parsimonious explanation for relations among obesity, mortality rate and aging?. International Journal of Obesity, 34(8), 1231-1238. DOI: 10.1038/ijo.2010.71
- November 18, 2010
- 05:39 AM
- 1,008 views
Fractals in clouds – why clouds appear ‘cloudlike’
by Croor Singh in Learning to be Terse
Clouds have distinctive shapes. Or they seem to have distinctive shapes. It turns out that is likely due to the fractal nature of clouds. The fractal nature of clouds was first shown in this paper in Science, from 1982.... Read more »
LOVEJOY, S. (1982) Area-Perimeter Relation for Rain and Cloud Areas. Science, 216(4542), 185-187. DOI: 10.1126/science.216.4542.185
- November 18, 2010
- 05:35 AM
- 775 views
Fractals in clouds
by Croor Singh in Learning to be Terse
Clouds have distinctive shapes. Or they seem to have distinctive shapes. It turns out that is likely due to the fractal nature of clouds. The fractal nature of clouds was first shown in this paper in Science, from 1982.... Read more »
LOVEJOY, S. (1982) Area-Perimeter Relation for Rain and Cloud Areas. Science, 216(4542), 185-187. DOI: 10.1126/science.216.4542.185
- November 16, 2010
- 12:00 PM
- 1,664 views
The more colourful the lie, the more people believe it, man!
by Caspar Addyman in Your Brain on Drugs
The Splintered Mind has a great guest piece by G. Randolph Mayes reflecting on John Allen Paulos’s latest piece in the New York Times, entitled “Stories vs. Statistics” , which reflects on counter intuitve work of Nobel prize winning work of Tversky and Kahneman on conjunction fallacies.... Read more »
Tversky, A., & Kahneman, D. (1983) Extensional versus intuitive reasoning: The conjunction fallacy in probability judgment. Psychological Review, 90(4), 293-315. DOI: 10.1037/0033-295X.90.4.293
- November 14, 2010
- 06:31 PM
- 737 views
The limits of the immune system
by David Basanta in Cancerevo: Cancer evolution
After spending a good part of Wednesday talking with scientists at the department of immunology at Moffitt I am well aware of the importance of the immune system as an anticancer mechanism. The immune system is not perfect though...... Read more »
Martin, L., & Coon, C. (2010) Infection Protection and Natural Selection. Science, 330(6004), 602-603. DOI: 10.1126/science.1198303
- November 13, 2010
- 12:04 PM
- 814 views
Broken Taboo: A Major Journal Publishes Evidence of ESP
by David Berreby in Mind Matters
Psi is psychology's equivalent of the perpetual motion machine in physics. Claims in favor of telepathy, clairvoyance, premonitions or other extra-sensory perceptions were always considered the realm of looney-tunes who write to professors with no margins and lots of fanciful diagrams. Or worse ...Read More
... Read more »
Daryl J. Bem. (2011) Feeling the future: Experimental evidence for anomalous retroactive influences on cognition and affect. Journal of Personality and Social Psychology. info:/10.1037/a0021524
- November 9, 2010
- 05:30 AM
- 785 views
The future babble of obesity prognostication
by Yoni Freedhoff in Weighty Matters
Lies, damn lies and statistics.Now to be fair I've been primed to disbelieve most future predictions by being mid-way through Dan Gardner's excellent Future Babble, but really, obesity rates to hit 42% is headline news?The headlines referred to a study published last week in PLoS Computational Biology that had some truly fancy Harvard folks hammer out a formula to predict what obesity's going to do down the road. Those fancy folks are building on a prior study of theirs that proved that obesity ........ Read more »
Hill, A., Rand, D., Nowak, M., & Christakis, N. (2010) Infectious Disease Modeling of Social Contagion in Networks. PLoS Computational Biology, 6(11). DOI: 10.1371/journal.pcbi.1000968
- November 5, 2010
- 09:29 AM
- 1,281 views
How many of us will be obese in 2050?
by Peter Janiszewski, Ph.D. in Obesity Panacea
Approximately 42% of the US population will be obese in 2050, according to a new study by Hill and colleagues from Harvard.
In the study, just published in PLoS Computational Biology, the authors predict the obesity epidemic will also plateau around this time. That is, 42% obesity rate is the predicted maximum level at which point an equilibrium will be reached.
The authors have this to say about their prediction:
While not great, this is a much more optimistic estimate than 100%.
That is certai........ Read more »
Hill, A., Rand, D., Nowak, M., & Christakis, N. (2010) Infectious Disease Modeling of Social Contagion in Networks. PLoS Computational Biology, 6(11). DOI: 10.1371/journal.pcbi.1000968
- November 1, 2010
- 09:28 AM
- 738 views
Few Women in Math-Intensive Fields
by APS Daily Observations in Daily Observations
Why are women so underrepresented in mathematics-intensive fields? This question is at the center of a storm of controversy, as some scientists suggest innate differences in ability and others blame ... Read more »
Ceci, S.J., . (2010) Sex differences in math-intensive fields. Current Directions in Psychological Science. info:/10.1177/0963721410383241
- October 27, 2010
- 04:18 PM
- 1,213 views
But did you correct your results using a dead salmon?
by Iddo Friedberg in Byte Size Biology
fMRI tests are very popular. Why should they not be? Take someone, stick them in an MRI, show them a picture of their mother-in-law, see which bits of their brain light up (get more blood, hence are more active) and voila! You’re in the New York Times science supplement under the title “Scientists discover brain region responsible for unmitigated rage.” (Any resemblance to any actual mother-in-law, living or dead, is purely coincidental.) fMRI is a great tool for mapping cogni........ Read more »
Craig M. Bennett, Abigail A. Baird, Michael B. Miller, & George L. Wolford. (2010) Neural Correlates of Interspecies Perspective Taking in the Post-Mortem Atlantic Salmon: An Argument For Proper Multiple Comparisons Correction. JSUR, 1(1), 1-5. info:other/http://jsur.org/v1n1p1
- October 27, 2010
- 01:41 AM
- 811 views
The Piffle Paradox - or how pure mathematicians have fun
by westius in Mr Science Show
Ever wondered how pure mathematicians have fun? The following is from the 1967 paper Modern Research in Mathematics by A. K. Austin, from the Department of Pure Mathematics at the University of Sheffield. It's a send-up, by the way...
A note on piffles by A. B. Smith
A. C. Jones in his paper "A Note on the Theory of Boffles," Proceedings of the National Society, 13, first defined a Biffle to be a non-definite Boffle and asked if every Biffle was reducible.
C. D. Brown in "On a paper by A. ........ Read more »
Austin, A. (1967) 3183. Modern Research in Mathematics. The Mathematical Gazette, 51(376), 149. DOI: 10.2307/3614400
Farlow, S. (1980) Three Mathematical Satires A rebuke of A. B. Smith's paper, 'A Note on Piffles'. International Journal of Mathematical Education in Science and Technology, 11(2), 285-304. DOI: 10.1080/0020739800110222
- October 25, 2010
- 07:38 PM
- 636 views
Finding Parameters for Cancer Progression and other Complex Biological Models
by Michael Long in Phased
Diego Fernandez Slezak (Buenos Aires University, Argentina), Gustavo Stolovitzky (IBM), and coworkers show that a mathematical "best fit" to a complex biological model may be biologically implausible.... Read more »
Fernández Slezak, D., Suárez, C., Cecchi, G. A., Marshall, G., & Stolovitzky, G. (2010) When the Optimal Is Not the Best: Parameter Estimation in Complex Biological Models. PLoS ONE, 5(10). DOI: 10.1371/journal.pone.0013283
- October 25, 2010
- 01:16 AM
- 638 views
Parametric Bootstrap Power Analysis of GISS Temp Data
by apeescape in mind of a Markov chain
Previosly, I calculated a bunch of ad-hoc power curves from GISTEMP data. Power is essentially a reframing of the p-value, to see the significance of the trend lines in the global temps. However, power calculations are inherently very noisy, hence, my ad-hoc way of aggregating the data. Another method is to bootstrap through the responses [...]... Read more »
Gerard, P., Smith, D., & Weerakkody, G. (1998) Limits of Retrospective Power Analysis. The Journal of Wildlife Management, 62(2), 801. DOI: 10.2307/3802357
- October 22, 2010
- 05:54 PM
- 755 views
Yes, diversity matters
by David Basanta in Cancerevo: Cancer evolution
Diversity matters and I am not talking about the workplace. It does in cancer (I am writing this from an NCI organised meeting in the context of the ICBP, where one one the main themes is the role of...... Read more »
Palmer TM, Doak DF, Stanton ML, Bronstein JL, Kiers ET, Young TP, Goheen JR, & Pringle RM. (2010) Synergy of multiple partners, including freeloaders, increases host fitness in a multispecies mutualism. Proceedings of the National Academy of Sciences of the United States of America, 107(40), 17234-9. PMID: 20855614
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