Items of some interest:

These are my recent Pin​board​.in links:

  • [1206.3340] Extrac­tion of Deep Phy­lo­ge­netic Sig­nal and Improved Res­o­lu­tion of Evo­lu­tion­ary Events within the recA/​RAD51 Phylogeny

    “The recA/​RAD51 gene fam­ily encodes a diverse set of recom­bi­nase pro­teins that effect homol­o­gous recom­bi­na­tion, DNA-​​repair, and genome sta­bil­ity. The recA gene fam­ily is expressed in almost all species of Eubac­te­ria, Archaea, and Eukary­otes, and even in some viruses. To date, efforts to resolve the deep evo­lu­tion­ary ori­gins of this ancient pro­tein fam­ily have been hin­dered, in part, by the high sequence diver­gence between fam­i­lies (i.e. ~30% iden­tity between par­al­o­gous groups). Through (i) large taxon sam­pling, (ii) the use of a phy­lo­ge­netic algo­rithm designed for mea­sur­ing highly diver­gent par­alogs, and (iii) novel Evo­lu­tion­ary Spa­tial Dynam­ics sim­u­la­tion and ana­lyt­i­cal tools, we obtained a robust, par­si­mo­nious and more refined phy­lo­ge­netic his­tory of the recA/​RAD51 super­fam­ily. Taken together, our model for the evo­lu­tion of recA/​RAD51 fam­ily pro­vides a bet­ter under­stand­ing of ancient ori­gin of recA pro­teins and mul­ti­ple events lead­ing to the diver­si­fi­ca­tion of recA homologs in eukary­otes, includ­ing the dis­cov­ery of addi­tional RAD51 sub-​​families.”

    cladis­tics algo­rithms visu­al­iza­tion deep-​​time sta­tis­tics
  • [1204.6547] Gen­er­at­ing self-​​organizing col­lec­tive behav­ior using sep­a­ra­tion dynam­ics from exper­i­men­tal data

    “Math­e­mat­i­cal mod­els for sys­tems of inter­act­ing agents using sim­ple local rules have been pro­posed and shown to exhibit emer­gent swarm­ing behav­ior. Most of these mod­els are con­structed by intu­ition or man­ual obser­va­tions of real phe­nom­ena, and later tuned or ver­i­fied to sim­u­late desired dynam­ics. In con­trast to this approach, we pro­pose using a model that attempts to fol­low an aver­aged rule of the essen­tial distance-​​dependent col­lec­tive behav­ior of real pigeon flocks, which was abstracted from exper­i­men­tal data. By using a sim­ple model to fol­low the behav­ioral ten­den­cies of real data, we show that our model can exhibit emer­gent self-​​organizing dynam­ics such as flock­ing, pat­tern for­ma­tion, and counter-​​rotating vor­tices. The range of behav­iors observed in our sim­u­la­tions are richer than the stan­dard mod­els of col­lec­tive dynam­ics, and should thereby give poten­tial for new mod­els of com­plex behavior.”

    agent-​​based swarms boids algo­rithms emergent-​​design
  • [1206.3555] A Dynamic Pro­gram­ming Algo­rithm for Infer­ence in Recur­sive Prob­a­bilis­tic Programs

    “We describe a dynamic pro­gram­ming algo­rithm for com­put­ing the mar­ginal dis­tri­b­u­tion of dis­crete prob­a­bilis­tic pro­grams. This algo­rithm takes a func­tional inter­preter for an arbi­trary prob­a­bilis­tic pro­gram­ming lan­guage and turns it into an effi­cient mar­gin­al­izer. Because direct caching of sub-​​distributions is impos­si­ble in the pres­ence of recur­sion, we build a graph of depen­den­cies between sub-​​distributions. This fac­tored sum-​​product net­work makes (poten­tially cyclic) depen­den­cies between sub­prob­lems explicit, and cor­re­sponds to a sys­tem of equa­tions for the mar­ginal dis­tri­b­u­tion. We solve these equa­tions by fixed-​​point iter­a­tion in topo­log­i­cal order. We illus­trate this algo­rithm on exam­ples used in teach­ing prob­a­bilis­tic mod­els, com­pu­ta­tional cog­ni­tive sci­ence research, and game theory.”

    recur­sion stochastic-​​programming sim­u­la­tion nudge
  • Share­able: Hack­ing Home: Col­iv­ing Rein­vents the Com­mune for a Net­worked Age

    ‘It was more than just a lux­ury home full of bril­liant young minds. Dubbed “an inten­tional com­mu­nity”, The Rain­bow Man­sion was an exper­i­ment in a new type of cohab­i­ta­tion. The house began host­ing hackathons and salons in its library, invit­ing Sil­i­con Valley’s best and bright­est to par­tic­i­pate. “Right away it set itself in motion,” Schin­gler says. “It had this sort of acci­den­tal mys­tique about it.”’

    cohous­ing col­lab­o­ra­tion nerd-​​culture
  • [1206.3369] A Suc­ces­sive Approx­i­ma­tion Algo­rithm for Com­put­ing the Divi­sor Sum­ma­tory Function

    “An algo­rithm is pre­sented to com­pute iso­lated val­ues of the divi­sor sum­ma­tory func­tion in O(n^(1/3)) time and O (log n) space. The algo­rithm is ele­men­tary and uses a geo­met­ric approach of suc­ces­sive approx­i­ma­tion com­bined with coor­di­nate transformation.”

    algo­rithms computational-​​geometry nudge-​​targets
  • [1204.3650] Evo­lu­tion­ary Meta­dy­nam­ics: a Novel Method to Pre­dict Crys­tal Structures

    “A novel method for crys­tal struc­ture pre­dic­tion, based on meta­dy­nam­ics and evo­lu­tion­ary algo­rithms, is pre­sented here. This tech­nique can be used to pro­duce effi­ciently both the ground state and metastable states eas­ily reach­able from a rea­son­able ini­tial struc­ture. We use the cell shape as col­lec­tive vari­able and evo­lu­tion­ary vari­a­tion oper­a­tors devel­oped in the con­text of the USPEX method [Oganov, Glass, textit{J. Chem. Phys.}, 2006, textbf{124}, 244704; Lyakhov textit{et al., Comp. Phys. Comm.}, 2010, textbf{181}, 1623; Oganov textit{et al., Acc. Chem. Res.}, 2011, textbf{44}, 227] to equi­li­brate the sys­tem as a func­tion of the col­lec­tive vari­ables. We illus­trate how this approach helps one to find sta­ble and metastable states for Al$_2$SiO$_5$, SiO$_2$, MgSiO$_3$, and car­bon. Apart from pre­dict­ing crys­tal struc­tures, the new method can also pro­vide insight into mech­a­nisms of phase transitions.”

    evolutionary-​​algorithms search-​​algorithms physics nudge-​​targets condensed-​​matter