D. Helbing, Simulation of pedestrian crowds in normal and evacuation situations, Pedestrian and evacuation dynamics, pp.21-58, 2002.

N. Máté, Hierarchical group dynamics in pigeon flocks, Nature, vol.464, issue.7290, p.890893, 2010.

T. Sanchez, Spontaneous motion in hierarchically assembled active matter, Nature, vol.8, issue.7424, pp.431-434, 2012.
DOI : 10.1039/b806706f

A. Baskaran and M. C. Marchetti, Nonequilibrium Statistical Mechanics of Self-propelled Hard Rods Journal of Statistical Mechanics: Theory and Experiment, p.4, 2010.

A. Baskaran and M. C. Marchetti, Self-regulation in selfpropelled nematic fluids, The European Physical Journal E, vol.359, pp.1-8, 2012.

. Ch and . Becco, Experimental evidences of a structural and dynamical transition in fish school " . en In: Physica A: Statistical Mechanics and its Applications 367, pp.487-493, 2006.

L. Berthier and G. Tarjus, The role of attractive forces in viscous liquids, The Journal of Chemical Physics, vol.134, issue.21, 2011.
DOI : 10.1063/1.3516210
URL : https://hal.archives-ouvertes.fr/hal-00600672

E. Bertin, M. Droz, and G. Gregoire, Boltzmann and hydrodynamic description for self-propelled particles arXiv: cond-mat/0601038, Physical Review E 74, 2006.
DOI : 10.1103/physreve.74.022101
URL : http://arxiv.org/pdf/cond-mat/0601038

E. Bertin, Comparison between Smoluchowski and Boltzmann approaches for self-propelled rods, Physical Review E 92, 2015.
DOI : 10.1103/PhysRevLett.113.258104
URL : https://hal.archives-ouvertes.fr/cea-01366722

D. Bi, Motility-Driven Glass and Jamming Transitions in Biological Tissues " . en In: Physical Review X 6, 2016.

N. Biais, Cooperative Retraction of Bundled Type IV Pili Enables Nanonewton Force Generation " . en, PLoS Biology, vol.6, issue.4, 2008.

A. Bottinelli, T. J. David, J. L. Sumpter, and . Silverberg, Emergent Structural Mechanisms for High-Density Collective Motion Inspired by Human Crowds " . en, In: Physical Review Letters, vol.11722, 2016.
DOI : 10.1103/physrevlett.117.228301
URL : http://arxiv.org/pdf/1606.08835

E. Michael, J. Cates, and . Tailleur, Motility-Induced Phase Separation " . en, In: Annual Review of Condensed Matter Physics, vol.6, issue.1, pp.219-244, 1947.

H. Chaté, Collective motion of self-propelled particles interacting without cohesion, Physical Review E 77, 2008.
DOI : 10.1103/PhysRevE.55.3898

L. F. Cugliandolo, G. Gonnella, and A. Suma, Rotational and translational diffusion in an interacting active dumbbell system, Physical Review E, vol.181, issue.6, p.62124, 2015.
DOI : 10.1007/BF01007642

W. Hendrick and . De-haan, Modeling and Simulating the Dynamics of Type IV Pili Extension of Pseudomonas aeruginosa " . en, Biophysical Journal, vol.11110, pp.2263-2273, 2016.

A. Doostmohammadi, Stabilization of active matter by flowvortex lattices and defect ordering, Nature communications, vol.7, 2016.

A. Einstein, Investigations on the Theory of the Brownian Movement, Courier Corporation, 1956.

P. De-gennes, F. Brochard-wyart, and D. Quéré, Gouttes, bulles, perles et ondes, 2002.

L. Giomi, Defect Annihilation and Proliferation in Active Nematics, Physical Review Letters, vol.110, issue.22, p.228101, 2013.
DOI : 10.1103/PhysRevLett.67.1574

L. Giomi, Defect dynamics in active nematics, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, vol.15, issue.8, pp.20130365-20130365, 2014.
DOI : 10.1080/02678299308031947

Y. Alexander, J. Grosberg, and . Joanny, Activity induced phase separation

K. Guevorkian, Aspiration of Biological Viscoelastic Drops, Physical Review Letters, vol.64, issue.21, 2010.
DOI : 10.2976/1.3086732
URL : https://hal.archives-ouvertes.fr/hal-01020626

D. Helbing, Simulation of pedestrian crowds in normal and evacuation situations, Pedestrian and evacuation dynamics, pp.21-58, 2002.

L. Gary, E. R. Hunter, and . Weeks, The physics of the colloidal glass transition In: Reports on progress in physics 75, p.66501, 2012.

A. A. Hyman, C. A. Weber, and F. Jülicher, Liquid-Liquid Phase Separation in Biology, Annual Review of Cell and Developmental Biology, vol.30, issue.1, pp.39-58, 2014.
DOI : 10.1146/annurev-cellbio-100913-013325

A. Ikeda, L. Berthier, and G. Biroli, Dynamic criticality at the jamming transition, 12A507. URL, 2013.
DOI : 10.1098/rsta.2009.0178
URL : https://hal.archives-ouvertes.fr/hal-00770499

G. Dumenil and A. Imhaus, The number of Neisseria meningitidis type IV pili determines host cell interaction, In: EMBO J, vol.33, pp.1767-1783, 2014.

M. Lindén, Force generation in small ensembles of Brownian motors, Physical Review E 74, 2006.
DOI : 10.1126/science.276.5314.917

B. Maier, The bacterial type IV pilus system ? a tunable molecular motor " . en, In: Soft Matter, vol.924, pp.5667-5671, 2013.
DOI : 10.1039/c3sm50546d

B. Maier, M. Koomey, and M. P. Sheetz, A forcedependent switch reverses type IV pilus retraction " . en, Proceedings of the National Academy of Sciences of the United States of America, pp.10961-10966, 2004.
DOI : 10.1073/pnas.0402305101
URL : http://www.pnas.org/content/101/30/10961.full.pdf

B. Maier, G. C. Wong, and . English, How Bacteria Use Type IV Pili Machinery on Surfaces, Trends in Microbiology, vol.23, issue.12, pp.775-788, 2015.
DOI : 10.1016/j.tim.2015.09.002

R. Marathe, Bacterial twitching motility is coordinated by a two-dimensional tug-of-war with directional memory, Nature Communications, vol.90, 2014.
DOI : 10.1016/j.bpj.2008.10.017

M. C. Marchetti, Soft Active Matter, 2012.

R. Samuel, A. Mccandlish, M. F. Baskaran, and . Hagan, Spontaneous segregation of self-propelled particles with different motilities, In: Soft Matter, vol.88, pp.2527-2534, 2012.

N. Máté, Hierarchical group dynamics in pigeon flocks, Nature, vol.464, issue.7290, p.890893, 2010.

K. H. Nagai, Collective Motion of Self-Propelled Particles with Memory, Physical Review Letters, vol.114, issue.16, 2015.
DOI : 10.1103/PhysRevLett.79.213
URL : https://hal.archives-ouvertes.fr/cea-01367162

M. Nagy, I. Daruka, and T. Vicsek, New aspects of the continuous phase transition in the scalar noise model (SNM) of collective motion, Physica A: Statistical Mechanics and its Applications, vol.373, 2007.
DOI : 10.1016/j.physa.2006.05.035

V. Narayan, S. Ramaswamy, and N. Menon, Long- Lived Giant Number Fluctuations in a Swarming Granular Nematic " . en In: Science 317, pp.105-108317, 2007.

S. Ngo, Large-Scale Chaos and Fluctuations in Active Nematics, Physical Review Letters, vol.34, issue.3, 2014.
DOI : 10.1038/nature10874
URL : https://hal.archives-ouvertes.fr/cea-01384279

B. Nicolas, Cooperative Retraction of Bundled Type IV Pili Enables Nanonewton Force Generation, PLoS Biol, vol.6, issue.4, p.87, 2008.

N. Ohshima and R. Nerem, Application of the micropipette technique to the measurement of cultured porcine aortic endothelial cell viscoelastic properties, Journal of biomechanical engineering, vol.112, p.263, 1990.

R. Enno and . Oldewurtel, Differential interaction forces govern bacterial sorting in early biofilms " . en, 2015.

U. Anand, J. Oza, and . Dunkel, Antipolar ordering of topological charges and universality in active liquid crystals In: arXiv:1507.01055 [cond-mat, physics:physics], 2015.

U. Anand, J. Oza, and . Dunkel, Nematic ordering of topological defects in active liquid crystals

F. Perrin, ??tude math??matique du mouvement brownien de rotation, Annales scientifiques de l'École Normale Supérieure, pp.1-51, 1928.
DOI : 10.24033/asens.782
URL : http://www.numdam.org/article/ASENS_1928_3_45__1_0.pdf

F. Peruani, A. Deutsch, and M. Baer, Nonequilibrium clustering of self-propelled rods, Physical Review E, vol.78, issue.3, p.30904, 2006.
DOI : 10.1103/PhysRevA.17.2067
URL : https://hal.archives-ouvertes.fr/hal-00905230

A. Peshkov, Nonlinear Field Equations for Aligning Self- Propelled Rods " . en, In: Physical Review Letters, vol.10926, 2012.
DOI : 10.1103/physrevlett.109.268701
URL : https://hal.archives-ouvertes.fr/hal-00910349

T. Sanchez, Spontaneous motion in hierarchically assembled active matter, Nature, vol.8, issue.7424, pp.431-434, 2012.
DOI : 10.1039/b806706f
URL : http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3499644

M. Leonard and . Sander, Diffusion-limited aggregation: A kinetic critical phenomenon? " en In: Contemporary Physics 41, pp.203-218, 2000.

X. Shi and Y. Ma, Topological structure dynamics revealing collective evolution in active nematics ISSN, Nature Communications, vol.4, pp.2041-1723, 2013.

I. Rhee, N. Minsu-shin, S. Hong, N. Lee, and S. Chong, Human mobility patterns and their impact on routing in human-driven mobile networks, HotNets-VI. 2007. URL: http://conferences.sigcomm.org/hotnets, pp.6-108, 2007.

A. P. Solon and J. Tailleur, Flocking with discrete symmetry: the 2d Active Ising Model In: Physical Review E 92, 2015.

A. P. Solon, H. Chaté, and J. Tailleur, From Phase to Microphase Separation in Flocking Models: The Essential Role of Nonequilibrium Fluctuations, Physical Review Letters, vol.114, issue.6, 2015.
DOI : 10.1103/PhysRevLett.108.248101
URL : https://hal.archives-ouvertes.fr/cea-01367258

P. Srivastava, P. Mishra, and M. C. Marchetti, Negative stiffness and modulated states in compressible active nematics, 2016.

J. Taktikos, Pili-Induced Clustering of N. gonorrhoeae Bacteria, e0137661. ISSN, pp.1932-6203, 2015.
DOI : 10.1371/journal.pone.0137661.s009

M. Tennenbaum, Mechanics of fire ant aggregations, Nature Materials, vol.29, issue.1, pp.54-59, 2015.
DOI : 10.1016/j.tibs.2004.05.003

E. Michael, T. , and D. A. Weitz, The Oxford Handbook of Soft Condensed Matter URL: http://books.google.com/books?hl=en&lr=&id=d726BwAAQBAJ& oi=fnd&pg=PP1&dq=%22in+a+liquid+that,+despite+the+ density+di%EF%AC%80erence+between+the%22+%22the+ work+of+Einstein+and+Perrin+laid+the+foundations+ of % 22 + %22colloids + are + model + systems, 2015.

J. Toner and Y. Tu, Long-range order in a two-dimensional dynamical XY model: how birds fly together, In: Physical Review Letters, vol.7523, p.4326, 1995.

T. Vicsek, Novel Type of Phase Transition in a System of Self-Driven Particles, Physical Review Letters, vol.1, issue.6, pp.1226-1229, 1995.
DOI : 10.1142/S0218348X93000320

M. Gandimohan and . Viswanathan, Optimizing the success of random searches, Nature, vol.4016756, pp.911-914, 1999.

J. Arthur, L. Vromans, and . Giomi, Orientational properties of nematic disclinations, 2015.

A. W. Andreas and . Müller, Janus Particles: Synthesis, Self-Assembly, Physical Properties, and Applications, In: Chemical Reviews, vol.113, issue.7, 2013.

C. A. Weber, Formation and dissolution of bacterial colonies " . en ISSN, In: Physical Review E, vol.923, pp.1539-3755, 2015.

N. Simon, C. A. Weber, E. Weber, and . Frey, Binary Mixtures of Particles with Different Diffusivities Demix, Physical Review Letters, vol.1165, 2016.

H. Wioland, Confinement Stabilizes a Bacterial Suspension into a Spiral Vortex " . en, In: Physical Review Letters, vol.11026, 2013.
DOI : 10.1103/physrevlett.110.268102
URL : http://doi.org/10.1103/physrevlett.110.268102

T. A. Witten-jr and L. M. Sander, Diffusion-Limited Aggregation, a Kinetic Critical Phenomenon, Physical Review Letters, vol.80, issue.19, pp.1400-1403, 1981.
DOI : 10.1016/0375-9601(80)90023-7

Y. Wu, Periodic reversal of direction allows Myxobacteria to swarm " . en, Proceedings of the National Academy of Sciences, pp.1222-1227, 1222.

B. Xing and W. Gao, Innovative computational intelligence: a rough guide to 134 clever algorithms, 2014.
DOI : 10.1007/978-3-319-03404-1

V. Zaburdaev, S. Denisov, and J. Klafter, Levy walks arXiv: 1410, In: Reviews of Modern Physics, vol.875100, issue.2, pp.483-530, 2015.

V. Zaburdaev, Uncovering the Mechanism of Trapping and Cell Orientation during Neisseria gonorrhoeae Twitching Motility " . en, Biophysical Journal, vol.1077, pp.1523-1531, 2014.

J. Zakrisson, Rigid multibody simulation of a helix-like structure: the dynamics of bacterial adhesion pili, European Biophysics Journal, vol.104, issue.5, pp.291-300, 2015.
DOI : 10.1016/j.bpj.2013.03.059

H. P. Zhang, Collective motion and density fluctuations in bacterial colonies " . en, Proceedings of the National Academy of Sciences, pp.31-13626, 2010.