Alternating linear-chain antiferromagnetism in copper nitrate Cu(NO\u3csub\u3e3\u3c/sub\u3e)\u3csub\u3e2\u3c/sub\u3e.2.5 H\u3csub\u3e2\u3c/sub\u3eO

Current interest in the behavior of Heisenberg alternating antiferromagnetic quantum chains has been stimulated by the discovery of an unusual class of magnetoelastic spin-Peierls systems. Copper nitrate, Cu(NO3)2.2.5 H2O, does not display a spin-Peierls transition, but its dominant magnetic behavior is that of a strongly alternating antiferromagnetic chain with temperature-independent alternation. A remarkable, simultaneous fit is demonstrated between theoretical studies and a wide variety of zero- (low-) field experimental measurements, including susceptibility, magnetization, and specific heat. The fitting parameters are α(degree of alternation) = 0.27, J1/k=2.58 K, gb=2.31, and g⊥=2.11. Slight systematic discrepancies are attributed to weak interchain coupling. Theoretical studies also predict a rich variety of behavior in high fields, particularly in the region involving the lower and upper critical fields, Hc1 = 28 kOe and Hc2 = 44 kOe. Experimental specific-heat measurements at H = 28.2 and 35.7 kOe show quantitative agreement with theory in this interesting parameter region. The fitting parameters are the same as for zero field and, again, small discrepancies between theory and experiment may be attributed to interchain coupling. The exceptional magnetic characterization of copper nitrate suggests its use for further experimental study in the vicinity of the high-field ordering region

Recommendations for the use of electrophysiological study: Update 2018

International audienceThe field of cardiac electrophysiology has greatly developed during the past decades. Consequently, the use of electrophysiological studies (EPSs) in clinical practice has also significantly augmented, with a progressively increasing number of certified electrophysiology centers and specialists. Since Zipes et al published the Guidelines for Clinical Intracardiac Electrophysiology and Catheter Ablation Procedures in 1995, no official document summarizing current EPS indications has been published.The current paper focuses on summarizing all relevant data of the role of EPS in patients with different types of cardiac pathologies and provides up-to-date recommendations on this topic.For this purpose, the PubMed database was screened for relevant articles in English up to December 2018 and ESC and ACC/AHA Clinical Practice Guidelines, and EHRA/HRS/APHRS position statements related to the current topic were analyzed.Current recommendations for the use of EPS in clinical practice are discussed and presented in 17 distinct cardiac pathologies. A short rationale, evidence, and indications are provided for each cardiac disease/group of diseases.In conclusion, because of its capability to establish a diagnosis in patients with a variety of cardiac pathologies, the EPS remains a useful tool in the evaluation of patients with cardiac arrhythmias and conduction disorders and is capable of establishing indications for cardiac device implantation and guide catheter ablation procedures