Presentation of IPhT : The Institute of Theoretical Physics (IPhT) is an Institute of the Direction of Fundamental Research (DRF) of the Commissariat for Atomic Energy and Alternative Energies (CEA).

Analysis of economic activities during a century of urban growth in Paris

Analysis of economic activities during a century of urban growth in Paris Evolution between 1829 and 1907 of the spatial distribution of cafes and restaurants in Paris. Researchers **Marc Barthelemy **(Institut de Physique Théorique and Centre d'Analyse et de Mathématique Sociales, EHESS), and **Julie Gravier **(Centre de Recherches Historiques and Centre d'Analyse et de Mathématique Sociales, EHESS) have just published in the prestigious journal Nature cities [1] their findings on the analysis of economic activities in a century of urban growth in the city of Paris.

Contemporary studies on the dynamics of economic activity in growing cities generally focus on periods of a few years or a few decades. Using a recently constructed geohistorical database containing around 1 million entries from historical directories, this study presents a detailed analysis of economic activities in Paris over almost a century (1829-1907).

The authors show that activities can be classified into three categories according to their dynamics and their scaling law in relation to population: (1) linear for everyday needs such as food and healthcare, (2) sublinear for public services such as education and administration, and (3) superlinear for specialized or temporary trends. The study also shows that these activities are highly sensitive to historical events, such as major public works or political conflicts, offering new insights into the evolution of activities in growing cities.

[1] Julie Gravier et Marc Barthelemy, A typology of activities over a century of urban growth, Nature Cities 1, pages 567–575 (2024)

E. De-laborderie, 2024-09-10 16:37:00

Jorge arrival at IPhT!

Jorge graduated in Theoretical Physics from the University of Havana (UH), Cuba. He then joined the Center of Molecular Immunology in Havana, a biopharmaceutical institution that develops therapeutic drugs for cancer and autoimmune diseases. He completed his Ph.D. on mathematical models of cellular metabolism in culture, visiting the Beatson Cancer Research Institute (Glasgow, UK) and the Politecnico di Torino (Italy).

Jorge then moved to Paris for a postdoctoral fellowship at ENS, where he worked on the statistical physics of unsupervised representation learning and applications to biological sequences. He was also awarded a PSL Junior Fellowship in Artificial Intelligence. He joins the IPhT on a CNRS "Junior Chair".

*Welcome to the IPhT, Jorge!*

R. Guida, 2024-09-04 11:41:00

Next Carlo Heissenberg's arrival at IPhT!

Carlo Heissenberg graduated with flying colors in 2019 from the Scuola Normale Superiore di Pisa, the Italian twin sister of the Ecole Normale de Paris. His initial research focused on the infrared properties of gravitational theories and higher spin theories from the perspective of asymptotic symmetries, a topic that later found phenomenological applications in the context of gravitational wave studies.

It was during his first postdoctoral period at Nordita-Uppsala (2019-2023) that Carlo started working on gravitational wave physics using ideas borrowed from particle physics, such as scattering amplitudes and eikonal exponentiation in particular. He quickly became a leader in the field, publishing several important papers with world-famous physicists such as Gabriele Veneziano. Carlo's group achieved, for instance, the first complete calculation of the gravitational deflection angle to the third post-Minkowskian order in the Newton coupling constant expansion, while simultaneously resolving the high-energy limit problem that was puzzling the community.

In the meantime, Carlo was granted a Marie-Curie fellowship and moved to his second postdoc at Queen Mary, while continuing to work on gravitational wave physics, focusing on new observables (waveforms, angular momentum loss, effect of spins…) that could be calculated efficiently using scattering amplitudes techniques.

**Carlo accepted an offer from the IPhT and will join the lab as a permanent member in Fall 2024.**

E. De-laborderie, 2024-07-18 10:17:00

Teaching ideal quantum measurements

2024-07-12 20:18:00

Next arrival of Olivier Gingras at IPhT!

2024-07-05 14:19:00

Supersymmetry Meets Random Matrices

2024-07-04 15:21:00

Magnetic quivers and Higgs mechanism

2024-06-28 19:15:00

Dilepton polarization as a signature of plasma anisotropy

2024-06-05 18:52:00

"Les Houches" International School of Physics (July 29- August 23)

2024-05-02 11:21:00

2024-05-02 10:36:00

The Institut de Physique Théorique celebrates Philippe Di Francesco's 60th birthday

2024-04-30 15:31:00

Measuring the speed of sound at 2.5 trillion degrees

2024-03-05 16:17:00

LISA mission gets the go-ahead from ESA

2024-01-26 16:35:00

2024-01-17 15:58:00

A Marc Barthélémy and Vincent Verbavatz's new book: Statistics of Urban populations.

2024-01-11 16:21:00

One IPhT scientist involved in the top 10 breakthroughs of 2023!

2024-01-10 10:55:00

Welcome to Anne Capdepon, Deputy Head of Research Support at the IPhT.

2023-12-14 09:54:00

The first images taken by Euclid revealed

2023-11-17 16:21:00

Celebration of IPHT's 60 years birthday

2023-11-17 15:42:00

A Starting ERC Grant for Ben Wieder

2023-09-06 15:32:00

Death of Michel Gaudin (02/12/1931 -- 04/08/2023)

2023-08-24 09:49:00

Efficient algorithms for scattering amplitudes

2023-07-12 15:18:00

Matt Von Hippel is to join IPhT on September 1.

2023-05-30 09:40:00

Monica Guica receives the CNRS bronze medal for the year 2023!

2023-04-03 15:21:00

27th Itzykson Conference : Fluctuations far from Equilibrium

2023-03-21 15:39:00

2023 Galileo Galilei Medal for David Kosower (IPhT), Zvi Bern(California U) and Lance Dixon (SLAC)

2023-02-17 09:04:00

Quantum networks : Entangled ions across the university campus Innsbruck

2023-02-10 15:11:00

Hamiltonian paths, a challenge for KPZ.

2023-02-03 15:19:00

Kibble-Zurek phenomenon: from the early Universe to a spin chain

2023-02-03 14:15:00

Kirone Mallick winner of the 2022 Physics French Society (SFP) Paul Langevin Prize

2023-02-01 15:18:00

EPS PhD prize awarded to IPhT student

2022-11-04 10:33:00

Retreat of the IPhT in Autrans : aftermath

2022-06-22 09:05:00

Arrival of Ben Wieder on next september

2022-06-17 15:12:00

Arrival of Dalimil Mazáč at IPhT

2022-06-07 10:14:00

Maps day at IPhT on 24 June 2022

2022-06-03 10:33:00

Quantum bounds and fluctuation-dissipation relations

2022-05-12 11:47:00

26ème conférence Itzykson : "Black-Hole Microstructure IV"

2022-05-12 10:32:00

Colloquium Rencontres de l'IPhT in Autrans (Vercors) from 23 to 25 May.

2022-05-12 10:02:00

An extension of Tutte's formula 60 years later

2022-04-20 11:13:00

2022-04-05 11:28:00

Public talk of Stephane Lavignac on Tuesday March 15th

2022-03-11 09:17:00

A new book written by Marc Barthélémy about spatial networks

2022-02-22 11:05:00

Cédric Villani at IPhT on March 1st

2022-02-22 10:26:00

Summer School in Cargèse around exotic superconductivity

2022-02-07 15:39:00

Langevin Prize of the French Society of Physics for Mariana Graña

2022-02-04 10:46:00

2022-02-01 09:21:00

Maxime Leroy joins the IPHT support team

2022-01-27 15:24:00

Un lien entre la masse du boson de Higgs et la constante cosmologique

2021-11-25 14:11:00

Conférence exceptionnelle de Cédric Villani le lundi 22 novembre à 19h30 (Institut Pascal)

2021-11-18 14:33:00

Mathematical Harmony and the Quantum World

2021-10-07 15:24:00

The art of mathematical physics

2021-09-01 16:31:00

Correlation functions and wave functions in solvable models

2021-08-31 16:44:00

2021-05-01 11:45:00

Multipole Ratios : A New Window into Black Holes

2020-11-27 15:16:00

Orazio Scarlatella lauréat du prix de thèse Physique des Ondes et de la Matière (PhOM) 2020

2020-11-26 11:07:00

Modeling the city: an equation ends centuries-old controversies

2020-11-19 11:10:00

Quantum entanglement: A single photon takes two optical paths by "entangling" them!

2020-10-15 15:06:00

An strongly secured encryption

2020-09-17 17:01:00

Un nouvel ouvrage co-écrit par Pierfrancesco Urbani, physicien à l’IPhT

2020-01-31 14:15:00

Un nouvel ouvrage co-écrit par Henri Orland, physicien à l'IPhT

2020-01-28 16:16:00

Gregory Soyez is the new IPhT Scientist Deputy Director

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Mon, Sep. 23rd, 14:15-17:00

Cours de physique théorique de Saclay - François Gélis

Mon, Sep. 30th, 11:00-12:00

Séminaire de physique mathématique - Sara Murciano

Mon, Sep. 30th, 14:15-17:00

Cours de physique théorique de Saclay - François Gélis

Tue, Oct. 01st, 14:00-15:00

Séminaire de physique des particules et de cosmologie - Quentin Bonnefoy

Mon, Oct. 07th, 14:15-17:00

Cours de physique théorique de Saclay - François Gélis