Classical Spin Liquid State in the S=5/2 Heisenberg Kagome Antiferromagnet Li_{9}Fe_{3}(P_{2}O_{7})_{3}(PO_{4})_{2}.

We investigate the low temperature magnetic properties of a S=5/2 Heisenberg kagome antiferromagnet, the layered monodiphosphate Li_{9}Fe_{3}(P_{2}O_{7})_{3}(PO_{4})_{2}, using magnetization measurements and ^{31}P nuclear magnetic resonance. An antiferromagnetic-type order sets in at T_{N}=1.3 K and a characteristic magnetization plateau is observed at 1/3 of the saturation magnetization below T^{*}∼5 K. A moderate ^{31}P NMR line broadening reveals the development of anisotropic short-range correlations concomitantly with a gapless spin-lattice relaxation time T_{1}∼k_{B}T/ℏS, which may point to the presence of a semiclassical nematic spin-liquid state predicted for the Heisenberg kagome antiferromagnetic model or to the persistence of the zero-energy modes of the kagome lattice under large magnetic fields.

Octupolar versus Néel Order in Cubic 5d

We report time-of-flight neutron spectroscopy and neutron and x-ray diffraction studies of the 5d^{2} double perovskite magnets, Ba_{2}MOsO_{6} (M=Zn,Mg,Ca). These materials host antiferromagnetically coupled 5d^{2} Os^{6+} ions decorating a face-centered cubic (fcc) lattice and are found to remain cubic down to the lowest temperatures. They all exhibit thermodynamic anomalies consistent with a single phase transition at a temperature T^{*}, and a gapped magnetic excitation spectrum with spectral weight concentrated at wave vectors typical of type-I antiferromagnetic orders. However, while muon spin resonance experiments show clear evidence for time-reversal symmetry breaking below T^{*}, we observe no corresponding magnetic Bragg scattering signal. These results are shown to be consistent with ferro-octupolar symmetry breaking below T^{*}, and are discussed in the context of other 5d double perovskite magnets and theories of exotic orders driven by multipolar interactions.

Emergence of long-range order in sheets of magnetic dimers.

Quantum spins placed on the corners of a square lattice can dimerize and form singlets, which then can be transformed into a magnetic state as the interactions between dimers increase beyond threshold. This is a strictly 2D transition in theory, but real-world materials often need the third dimension to stabilize long-range order. We use high pressures to convert sheets of Cu(2+) spin 1/2 dimers from local singlets to global antiferromagnet in the model system SrCu2(BO3)2. Single-crystal neutron diffraction measurements at pressures above 5 GPa provide a direct signature of the antiferromagnetic ordered state, whereas high-resolution neutron powder and X-ray diffraction at commensurate pressures reveal a tilting of the Cu spins out of the plane with a critical exponent characteristic of 3D transitions. The addition of anisotropic, interplane, spin-orbit terms in the venerable Shastry-Sutherland Hamiltonian accounts for the influence of the third dimension.

From spin glass to quantum spin liquid ground states in molybdate pyrochlores.

We present new magnetic heat capacity and neutron scattering results for two magnetically frustrated molybdate pyrochlores: S=1 oxide Lu_{2}Mo_{2}O_{7} and S=1/2 oxynitride Lu_{2}Mo_{2}O_{5}N_{2}. Lu_{2}Mo_{2}O_{7} undergoes a transition to an unconventional spin glass ground state at T_{f}∼16 K. However, the preparation of the corresponding oxynitride tunes the nature of the ground state from spin glass to quantum spin liquid. The comparison of the static and dynamic spin correlations within the oxide and oxynitride phases presented here reveals the crucial role played by quantum fluctuations in the selection of a ground state. Furthermore, we estimate an upper limit for a gap in the spin excitation spectrum of the quantum spin liquid state of the oxynitride of Δ∼0.05 meV or Δ/|θ|∼0.004, in units of its antiferromagnetic Weiss constant θ∼-121 K.

[Lipofilling in the management of breast cancer: An update based on a literature review and national and international guidelines]. / Le lipomodelage du sein dans un contexte cancérologique : mise au point à partir d'une revue de littérature actualisée et des référentiels nationaux et internationaux.

BACKGROUND: Lipomodelling (LM) is an increasingly used technique to reconstruct or correct an aesthetic defect linked to a loss of substance. In France, the Haute Autorité de santé (HAS) published recommendations in 2015 and 2020 concerning the conditions of use of LM on the treated and contralateral breast. These appear to be inconsistently followed. METHODS: Twelve members of the Senology Commission of the Collège national des gynécologues-obstétriciens français (French College of Gynecologists and Obstetricians) reviewed the carcinological safety of LM and the clinical and radiological follow-up of patients after breast cancer surgery, based on French and international recommendations and a review of the literature. The bibliographic search was conducted via Medline from 2015 to 2022, selecting articles in French and English and applying PRISMA guidelines. RESULTS: A total of 14 studies on the oncological safety of LM, 5 studies on follow-up and 7 guidelines were retained. The 14 studies (6 retrospective, 2 prospective and 6 meta-analyses) had heterogeneous inclusion criteria and variable follow-up, ranging from 38 to 120 months. Most have shown no increased risk of locoregional or distant recurrence after LM. A retrospective case-control study (464 LMs and 3100 controls) showed, in patients who had no recurrence at 80 months, a subsequent reduction in recurrence-free survival after LM in cases of luminal A cancer, highlighting the number of lost to follow-up (more than 2/3 of luminal A cancers). About follow-up after LM, the 5 series showed the high frequency after LM of clinical mass and radiological images (in » of cases), most often corresponding to cytosteatonecrosis. Most of the guidelines highlighted the uncertainties concerning oncological safety of LM, due to the lack of prospective data and long-term follow-up. DISCUSSION AND PERSPECTIVES: The members of the Senology Commission agree with the conclusions of the HAS working group, in particular by advising against LM "without cautionary periods", excessively, or in cases of high risk of relapse, and recommend clear, detailed information to patients before undergoing LM, and the need for postoperative follow-up. The creation of a national registry could address most questions regarding both the oncological safety of this procedure and the modalities of patient follow-up.

Singlet ground state of the quantum antiferromagnet Ba(3)CuSb(2)O(9).

We present local probe results on the honeycomb lattice antiferromagnet Ba(3)CuSb(2)O(9). Muon spin relaxation measurements in a zero field down to 20 mK show unequivocally that there is a total absence of spin freezing in the ground state. Sb NMR measurements allow us to track the intrinsic susceptibility of the lattice, which shows a maximum at around 55 K and drops to zero in the low-temperature limit. The spin-lattice relaxation rate shows two characteristic energy scales, including a field-dependent crossover to exponential low-temperature behavior, implying gapped magnetic excitations.

Kapellasite: a kagome quantum spin liquid with competing interactions.

Magnetic susceptibility, NMR, muon spin relaxation, and inelastic neutron scattering measurements show that kapellasite, Cu3Zn(OH)6Cl2, a geometrically frustrated spin-1/2 kagome antiferromagnet polymorphic with herbertsmithite, is a gapless spin liquid showing unusual dynamic short-range correlations of noncoplanar cuboc2 type which persist down to 20 mK. The Hamiltonian is determined from a fit of a high-temperature series expansion to bulk susceptibility data and possesses competing exchange interactions. The magnetic specific heat calculated from these exchange couplings is in good agreement with experiment. The temperature dependence of the magnetic structure factor and the muon relaxation rate are calculated in a Schwinger-boson approach and compared to experimental results.

[Techniques and complications of non-genetic risk reducing mastectomies: Guidelines of the National College of French Gynecologists and Obstetricians (CNGOF)]. / Modalités et morbidité des mastectomies de réduction de risque en dehors du risque avéré de prédisposition héréditaire : recommandations du Collège national des gynécologues et obstétriciens français (CNGOF).

OBJECTIVE: Based on an updated review of the international literature covering the different surgical techniques and complications of risk reducing mastectomies (RRM) in non-genetic context, the Commission of Senology (CS) of the College National des Gynécologues Obstétriciens Français (CNGOF) aimed to establish recommendations on the techniques to be chosen and their implementation. DESIGN: The CNGOF CS, composed of 24 experts, developed these recommendations. A policy of declaration and monitoring of links of interest was applied throughout the process of making the recommendations. Similarly, the development of these recommendations did not benefit from any funding from a company marketing a health product. The CS adhered to and followed the AGREE II (Advancing guideline development, reporting and evaluation in healthcare) criteria and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) method to assess the quality of the evidence on which the recommendations were based. The potential drawbacks of making recommendations in the presence of poor quality or insufficient evidence were highlighted. METHODS: The CS considered 6 questions in 4 thematic areas, focusing on oncologic safety, risk of complications, aesthetic satisfaction and psychological impact, and preoperative modalities. RESULTS: The application of the GRADE method resulted in 7 recommendations, 6 with a high level of evidence (GRADE 1±) and 1 with a low level of evidence (GRADE 2±). CONCLUSION: There was significant agreement among the CS members on recommendations for preferred surgical techniques and practical implementation.

[Spinal infections: typical and atypical imaging features]. / Infections rachidiennes: aspects typiques et atypiques.

While the imaging features of established spondylodiscitis are well known, other presentations may be misleading. The purpose of this article is to review the typical imaging features of spondylodiscitis as well as some more atypical and unusual imaging features (early spondylodiscitis, sceptic spondylitis, septic arthritis of facet joints, primary epidural abscess, unusual germs, neonate).

Comparison of breast density assessment between human eye and automated software on digital and synthetic mammography: Impact on breast cancer risk.

PURPOSE: To evaluate the agreement between automatic assessment software of breast density based on artificial intelligence (AI) and visual assessment by a senior and a junior radiologist, as well as the impact on the assessment of breast cancer risk (BCR) at 5 years. MATERIALS AND METHODS: We retrospectively included 311 consecutive women (mean age, 55.6±8.5 [SD]; range: 40-74 years) without a personal history of breast cancer who underwent routine mammography between January 1, 2019 and February 28, 2019. Mammographic breast density (MBD) was independently evaluated by a junior and a senior reader on digital mammography (DM) and synthetic mammography (SM) using BI-RADS (5th edition) and by an AI software. For each MBD, BCR at 5 years was estimated per woman by the AI software. Interobserver agreement for MBD between the two readers and the AI software were evaluated by quadratic κ coefficients. Reproducibility of BCR was assessed by intraclass correlation coefficient (ICC). RESULTS: Agreement for MBD assessment on DM and SM was almost perfect between senior and junior radiologists (κ=0.88 [95% CI: 0.84-0.92] and κ=0.86 [95% CI: 0.82-0.90], respectively) and substantial between the senior radiologist and AI (κ=0.79; 95% CI: 0.73-0.84). There was substantial agreement between DM and SM for the senior radiologist (κ=0.79; 95% CI: 0.74-0.84). BCR evaluation at 5 years was highly reproducible between the two radiologists on DM and SM (ICC=0.98 [95% CI: 0.97-0.98] for both), between BCR evaluation based on DM and SM evaluated by the senior (ICC=0.96; 95% CI: 0.95-0.97) or junior radiologist (ICC=0.97; 95% CI: 0.96-0.98) and between the senior radiologist and AI (ICC=0.96; 95% CI: 0.95-0.97). CONCLUSION: This preliminary study demonstrates a very good agreement for BCR evaluation based on the evaluation of MBD by a senior radiologist, junior radiologist and AI software.

[Hepatic and extrahepatic alveolar echinococcosis: CT and MR imaging features]. / Echinococcose alvéolaire hépatique et extra-hépatique : revue iconographique en scanner et en IRM.

To illustrate the CT and MR imaging features of alveolar echinococcosis, a rare disease that is endemic in the northeast of France. Hepatic and extrahepatic manifestations are presented. Fibrous and necrotic features are demonstrated on MR. Calcifications are demonstrated on CT. Accurate imaging diagnosis will exclude tumors (cholangiocarcinoma, cystadenoma, fibrous metastases) and avoid unnecessary biopsy.

[New possibilities to study biliary tree and gallbladder: functional magnetic resonance cholangiography contrast-enhanced with mangafodipir trisodium (Mn DPDP)]. / Les nouvelles possibilités d'exploration des voies biliaires en IRM: de l'imagerie morphologique à l'imagerie fonctionnelle avec perfusion de Mangafodipir Trisodium (Mn DPDP).

Mangafodipir trisodium (Teslascan) is a hepatobiliary contrast agent that provides noninvasive opacification of the bile ducts. Using this contrast medium combined with a T1-weighted gradient echo enhanced sequence provides functional imaging of the bile ducts. Second-intention MRI was obtained after the usual morphological study of the bile ducts using heavily T2-weighted sequences (SS-FSE Te eff long and SS FSE Te eff short). This method can detect many biliary duct anomalies: biliary leakage in the postoperative context, mapping of bile ducts and the gallbladder in the search for anatomical variants, analysis of biliodigestive or biliobiliary anastomoses, or a dynamic study of bile secretion and excretion. Opacification of the bile ducts has only been possible until now with invasive tests aggravated by a certain co-morbidity rate and their functional study using biliary scintigraphy limited by mediocre spatial resolution. This new possibility provides access not only to morphological imaging, but also to functional imaging with excellent spatial resolution.

[CT enteroclysis: a pictorial essay]. / L'enteroscanner: revue iconographique.

The objective of the CT-enteroclysis is to distend the entire small intestine equally and sufficiently using a nasojejunal probe and an enteroclysis catheter for administration of a neutral opacifying agent. Today this is the best radiological method available to explore the small intestine because of its good spatial resolution and the rapidity of the exam. It is a high-performance exam when searching for transmural and extramural pathologies, in particular small tumoral lesions. It remains less effective in the exploration of anomalies of the lumen's mucosal lining, contrary to videocapsule endoscopy and the double-balloon enteroscope. It has been recognized that the CT-enteroclysis is a high-performance examination that should replace the small-bowel follow-through exam. However, there are undeniable disadvantages: higher does of radiation, patient discomfort during placement of the enteroclysis catheter, false-positive results, long interpretation time, and the impossibility of exploring the endoluminal aspect of the intestinal mucosal lining. All radiologists should therefore become familiar with the problems involved with this exam and its signs and patterns, which are illustrated in this pictorial review.

[Liver and focal liver contrast: radiologic-pathologic correlation]. / Foie et contraste des lésions focales: corrélation radio-histologique.

Knowledge of the histological features of different components of a liver lesion greatly assists radiologists because it provides understanding of the correspondingimaging features. The imaging characteristics of lesions depend on variations of the extracellular architecture, mainly surrounding stromal tissue. Until histological imaging techniques become available, cellular analysis relies on optical microscopy and immunohistochemistry. Recent advances in imaging techniques now provide additional information on lesions due to improved spatial, temporal and contrast resolution. Correct interpretation of these imaging features should improve diagnosis.

Ground state selection under pressure in the quantum pyrochlore magnet Yb2Ti2O7.

A quantum spin liquid is a state of matter characterized by quantum entanglement and the absence of any broken symmetry. In condensed matter, the frustrated rare-earth pyrochlore magnets Ho2Ti2O7 and Dy2Ti2O7, so-called spin ices, exhibit a classical spin liquid state with fractionalized thermal excitations (magnetic monopoles). Evidence for a quantum spin ice, in which the magnetic monopoles become long range entangled and an emergent quantum electrodynamics arises, seems within reach. The magnetic properties of the quantum spin ice candidate Yb2Ti2O7 have eluded a global understanding and even the presence or absence of static magnetic order at low temperatures is controversial. Here we show that sensitivity to pressure is the missing key to the low temperature behaviour of Yb2Ti2O7. By combining neutron diffraction and muon spin relaxation on a stoichiometric sample under pressure, we evidence a magnetic transition from a disordered, non-magnetic, ground state to a splayed ferromagnetic ground state.

Tractography of peripheral nerves and skeletal muscles.

The assessment of human peripheral nerves and skeletal muscles by means of diffusion tensor imaging and tractograpy has been a recent area of research. These techniques have been successfully applied in both volunteers and patients, providing non-invasively, quantitative microstructural parameters (mainly mean fractional anisotropy and apparent diffusion coefficient) and offering a three-dimensional visualization tool of nerves and muscles fibers. DTI and tractography may reveal abnormalities that are beyond the resolution of conventional MR techniques and hence open the way to potential clinical applications. In this article, we will first summarize the current state of DTI and tractography in the evaluation of peripheral nerves and skeletal muscles as well as their potential future clinical applications. Then, we will address important technical considerations, which understanding is necessary to appropriately apply DTI and tractograhy, and in order to understand the current limitations of these innovative and promising techniques.