Extension of the Hamaneh - Taylor model using the macroscopic polarization for the description of chiral smectic liquid crystals

Chiral smectic liquid crystals exhibit a series of phases, including ferroelectric, antiferroelectric and ferrielectric commensurate structures as well as an incommensurate SmCalpha phase. We carried out an extension of the phenomenological model, recently presented by M. B. Hamaneh and P. L. Taylor, based upon the distorted clock model

Hervé Étienne Auguste Albans Faye Une biographie de jeunesse

Hervé Étienne Auguste Albans Faye Une biographie de jeunesseSABIX (Bulletin de la Société des Amis de la Bibliothèque et de l'Histoire de l'École polytechnique

Hervé Étienne Auguste Albans Faye Une biographie de jeunesse

Hervé Étienne Auguste Albans Faye Une biographie de jeunesseSABIX (Bulletin de la Société des Amis de la Bibliothèque et de l'Histoire de l'École polytechnique

High expression of HMGA2 independently predicts poor clinical outcomes in acute myeloid leukemia

In acute myeloid leukemia (AML), risk stratification based on cytogenetics and mutation profiling is essential but remains insufficient to select the optimal therapy. Accurate biomarkers are needed to improve prognostic assessment. We analyzed RNA sequencing and survival data of 430 AML patients and identified HMGA2 as a novel prognostic marker. We validated a quantitative PCR test to study the association of HMGA2 expression with clinical outcomes in 358 AML samples. In this training cohort, HMGA2 was highly expressed in 22.3% of AML, mostly in patients with intermediate or adverse cytogenetics. High expression levels of HMGA2 (H + ) were associated with a lower frequency of complete remission (58.8% vs 83.4%, P < 0.001), worse 3-year overall survival (OS, 13.2% vs 43.5%, P < 0.001) and relapse-free survival (RFS, 10.8% vs 44.2%, P < 0.001). A positive HMGA2 test also identified a subgroup of patients unresponsive to standard treatments. Multivariable analyses showed that H + was independently associated with significantly worse OS and RFS, including in the intermediate cytogenetic risk category. These associations were confirmed in a validation cohort of 260 patient samples from the UK NCRI AML17 trial. The HMGA2 test could be implemented in clinical trials developing novel therapeutic strategies for high-risk AML

Field-temperature phase diagrams in chiral tilted smectics, evidencing ferroelectric and ferrielectric phases

Usual ferroelectric compounds undergo a paraelectric-to-ferroelectric phase transition when the susceptibility of the electric polarization density changes its sign. The temperature is the only thermo-dynamic field that governs the phase transition. Chiral tilted smectics may also present an improper ferroelectricity when there is a tilt angle between the average long axis direction and the layer normal. The tilt angle is the order parameter of the phase transition which is governed by the temperature. Although the electric susceptibility remains positive, a polarization proportional to the tilt appears due to their linear coupling allowed by the chiral symmetry. Further complications come in when the chirality increases, as new phases are encountered with the same tilt inside the layers but a distribution of the azimuthal direction which is periodic with a unit cell of two (SmC∗ A), three (SmC∗ Fi1), four (SmC∗Fi2) or more (SmC∗ ) layers. In most of these phases, the layer normal is a symmetry axis so there is no macroscopic polarization except for the SmC∗Fi1 in which the average long axis is tilted so the phase is ferrielectric. By studying a particular compound with only a SmC∗ Fi2 and a SmC∗ phase, we show that we recover the uniformly tilted ferroelectric SmC∗ when applying an electric field. We are thus led to build field-temperature phase diagrams for this class of compounds by combining different experimental techniques described here