Dipanjan Roy - Academia.edu (original) (raw)
Uploads
Papers by Dipanjan Roy
Physical Review E, 2011
Phase models are among the simplest neuron models reproducing spiking behavior, excitability, and... more Phase models are among the simplest neuron models reproducing spiking behavior, excitability, and bifurcations toward periodic firing. However, coupling among neurons has been considered only using generic arguments valid close to the bifurcation point, and the differentiation between electric and synaptic coupling remains an open question. In this work we aim to address this question and derive a mathematical formulation for the various forms of coupling. We construct a mathematical model based on a planar simplification of the Morris-Lecar model. Based on geometric arguments we then derive a phase description of a network of the above oscillators with biologically realistic electric coupling and subsequently with chemical coupling under fast synapse approximation. We demonstrate analytically that electric and synaptic coupling are differently expressed on the level of the network's phase description with qualitatively different dynamics. Our mathematical analysis shows that a breaking of the translational symmetry in the phase flows is responsible for the different bifurcations paths of electric and synaptic coupling. Our numerical investigations confirm these findings and show excellent correspondence between the dynamics of the full network and the network's phase description.
Nature Communications, 2011
The dependence of the rate of proton–proton interactions on the centre-of-mass collision energy,√... more The dependence of the rate of proton–proton interactions on the centre-of-mass collision energy,√ s, is of fundamental importance for both hadron collider physics and particle astrophysics. The dependence cannot yet be calculated from first principles; therefore, experimental measurements are needed. Here we present the first measurement of the inelastic proton–proton interaction cross-section at a centre-of-mass energy,√ s, of 7 TeV using the ATLAS detector at the Large Hadron Collider. Events are selected by ...
A search for the Standard Model Higgs boson in proton-proton collisions with the ATLAS detector a... more A search for the Standard Model Higgs boson in proton-proton collisions with the ATLAS detector at the LHC is presented. The datasets used correspond to integrated luminosities of approximately 4.8 fb −1 collected at √ s = 7 TeV in 2011 and 5.8 fb −1 at √ s = 8 TeV in 2012. Individual searches in the channels H→ ZZ (*) → 4ℓ, H→ γγ and H→ WW (*) → eνµν in the 8 TeV data are combined with previously published results of searches for H→ ZZ (*) , WW (*) , bb and τ + τ − in the 7 TeV data and results from improved analyses of the H→ ZZ (*) → 4ℓ and H→ γγ channels in the 7 TeV data. Clear evidence for the production of a neutral boson with a measured mass of 126.0 ± 0.4 (stat) ± 0.4 (sys) GeV is presented. This observation, which has a significance of 5.9 standard deviations, corresponding to a background fluctuation probability of 1.7 × 10 −9 , is compatible with the production and decay of the Standard Model Higgs boson.
Physical Review E, 2011
Phase models are among the simplest neuron models reproducing spiking behavior, excitability, and... more Phase models are among the simplest neuron models reproducing spiking behavior, excitability, and bifurcations toward periodic firing. However, coupling among neurons has been considered only using generic arguments valid close to the bifurcation point, and the differentiation between electric and synaptic coupling remains an open question. In this work we aim to address this question and derive a mathematical formulation for the various forms of coupling. We construct a mathematical model based on a planar simplification of the Morris-Lecar model. Based on geometric arguments we then derive a phase description of a network of the above oscillators with biologically realistic electric coupling and subsequently with chemical coupling under fast synapse approximation. We demonstrate analytically that electric and synaptic coupling are differently expressed on the level of the network's phase description with qualitatively different dynamics. Our mathematical analysis shows that a breaking of the translational symmetry in the phase flows is responsible for the different bifurcations paths of electric and synaptic coupling. Our numerical investigations confirm these findings and show excellent correspondence between the dynamics of the full network and the network's phase description.
Nature Communications, 2011
The dependence of the rate of proton–proton interactions on the centre-of-mass collision energy,√... more The dependence of the rate of proton–proton interactions on the centre-of-mass collision energy,√ s, is of fundamental importance for both hadron collider physics and particle astrophysics. The dependence cannot yet be calculated from first principles; therefore, experimental measurements are needed. Here we present the first measurement of the inelastic proton–proton interaction cross-section at a centre-of-mass energy,√ s, of 7 TeV using the ATLAS detector at the Large Hadron Collider. Events are selected by ...
A search for the Standard Model Higgs boson in proton-proton collisions with the ATLAS detector a... more A search for the Standard Model Higgs boson in proton-proton collisions with the ATLAS detector at the LHC is presented. The datasets used correspond to integrated luminosities of approximately 4.8 fb −1 collected at √ s = 7 TeV in 2011 and 5.8 fb −1 at √ s = 8 TeV in 2012. Individual searches in the channels H→ ZZ (*) → 4ℓ, H→ γγ and H→ WW (*) → eνµν in the 8 TeV data are combined with previously published results of searches for H→ ZZ (*) , WW (*) , bb and τ + τ − in the 7 TeV data and results from improved analyses of the H→ ZZ (*) → 4ℓ and H→ γγ channels in the 7 TeV data. Clear evidence for the production of a neutral boson with a measured mass of 126.0 ± 0.4 (stat) ± 0.4 (sys) GeV is presented. This observation, which has a significance of 5.9 standard deviations, corresponding to a background fluctuation probability of 1.7 × 10 −9 , is compatible with the production and decay of the Standard Model Higgs boson.