7,669 research outputs found
Local phase space and edge modes for diffeomorphism-invariant theories
We discuss an approach to characterizing local degrees of freedom of a
subregion in diffeomorphism-invariant theories using the extended phase space
of Donnelly and Freidel, [JHEP 2016 (2016) 102]. Such a characterization is
important for defining local observables and entanglement entropy in
gravitational theories. Traditional phase space constructions for subregions
are not invariant with respect to diffeomorphisms that act at the boundary. The
extended phase space remedies this problem by introducing edge mode fields at
the boundary whose transformations under diffeomorphisms render the extended
symplectic structure fully gauge invariant. In this work, we present a general
construction for the edge mode symplectic structure. We show that the new
fields satisfy a surface symmetry algebra generated by the Noether charges
associated with the edge mode fields. For surface-preserving symmetries, the
algebra is universal for all diffeomorphism-invariant theories, comprised of
diffeomorphisms of the boundary, transformations of the
normal plane, and, in some cases, normal shearing transformations. We also show
that if boundary conditions are chosen such that surface translations are
symmetries, the algebra acquires a central extension.Comment: 29+12 pages, references added and minor typos fixe
Natriuretic Peptides in the Cardiovascular System. Multifaceted Roles in Physiology, Pathology and Therapeutics
The natriuretic peptides (NPs) family includes a class of hormones and their receptors needed for the physiological control of cardiovascular functions. The discovery of NPs provided a fundamental contribution into our understanding of the physiological regulation of blood pressure, and of heart and kidney functions. NPs have also been implicated in the pathogenesis of several cardiovascular diseases (CVDs), including hypertension, atherosclerosis, heart failure, and stroke. A fine comprehension of the molecular mechanisms dependent from NPs and underlying the promotion of cardiovascular damage has contributed to improve our understanding of the molecular basis of all major CVDs. Finally, the opportunity to target NPs in order to develop new therapeutic tools for a better treatment of CVDs has been developed over the years. The current Special Issue of the Journal covers all major aspects of the molecular implications of NPs in physiology and pathology of the cardiovascular system, including NP-based therapeutic approaches
Lectotypification of <i>Artemisia variabilis</i> Ten. (Compositae)
The name Artemisia variabilis Ten. is here lectotypified. Observations and synonyms are given
Resetting the neurohormonal balance in heart failure (HF). the relevance of the natriuretic peptide (NP) system to the clinical management of patients with HF
The natriuretic peptide (NP) system, which includes atrial natriuretic peptide, B-type natriuretic peptide, and C-type natriuretic peptide, has an important role in cardiovascular homeostasis, promoting a number of physiological effects including diuresis, vasodilation, and inhibition of the renin-angiotensin-aldosterone system. Heart failure (HF) is associated with defects in NP processing and synthesis, and there is a strong relationship between NP levels and disease state. NPs are useful biomarkers in HF, and their use in diagnosis and evaluation of prognosis is well established, particularly in patients with HF with reduced ejection fraction (HFrEF). There has also been interest in their use to guide disease management and therapeutic decision making. An understanding of NPs in HF has also resulted in interest in synthetic NPs for the treatment of HF and in treatments that target neprilysin, a protease that degrades NPs. A novel drug, the angiotensin receptor neprilysin inhibitor sacubitril/valsartan (LCZ696), which simultaneously inhibits neprilysin and blocks the angiotensin II type I receptor, was shown to have a favorable efficacy and safety profile in patients with HFrEF and has been approved for use in such patients in Europe and the USA. In light of the development of treatments that target neprilysin and of recent data in relation to synthetic NPs, it is timely to review the current understanding of the role of NPs in HF and their use in diagnosis, evaluating prognosis and guiding treatment, as well as their place in HF therapy
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