Books published by Mdpi AG

A challenging frontier in modern statistical physics concerns systems with a small number of degrees of freedom, far from the thermodynamic limit. Beyond the general interest in the foundation of statistical mechanics, the relevance of this subject is due to the recent increase of resolution in the observation and manipulation of biological and man-made objects at micro- and nano-scales. A peculiar feature of small systems is the role played by fluctuations, which cannot be neglected and are responsible for many non-trivial behaviors. The study of fluctuations of thermodynamic quantities, such as energy or entropy, goes back to Einstein, Onsager, and Kubo; more recently, interest in this matter has grown with the establishment of new fluctuation–dissipation relations, and of so-called stochastic thermodynamics. This turning point has received a strong impulse from the study of systems that are far from the thermodynamic equilibrium, due to very long relaxation times, as in disordered systems, or due to the presence of external forcing and dissipation, as in granular or active matter. Applications of the thermodynamic and statistical mechanics of small systems range from molecular biology to micro-mechanics, including models of nano-transport, Brownian motors, and (living or artificial) self-propelled organisms.

Positron emission tomography (PET) and single-photon emission computed tomography (SPECT) are in vivo molecular imaging techniques which are widely used in nuclear medicine for the diagnosis and treatment follow-up of many major diseases. They use biomolecules as probes, which are labeled with radionuclides of short half-lives, synthesized prior to the imaging studies. These probes are called radiopharmaceuticals. Their design and development require a rather interdisciplinary process involving many different disciplines of natural and health sciences. In addition to their diagnostic and therapeutic purposes in the field of nuclear medicine, radiopharmaceuticals provide powerful tools for in vivo pharmacology during the process of pre-clinical drug development to identify new drug targets, investigate the pathophysiology of diseases, discover potential drug candidates, and evaluate the pharmacokinetics and pharmacodynamics of drugs in vivo. Furthermore, they allow molecular imaging studies in various small-animal models of disease, including genetically engineered animals. The current collection of articles provides unique examples covering all major aspects in the field.

Many major cities of the world face challenges arising from growing and urbanizing populations, a changing climate, and an increase in the frequency of extreme weather events. Existing centralized water services, operating at, or close to, full capacity, are not sufficient to cope with the associated increase in water demand.Replacing the entire centralized infrastructure is very difficult within the existing environmental and economic constraints. Water services can be provided through the integration of decentralized and centralized systems, which are referred to herein as hybrid water supply systems.This Special Issue presents 12 papers encompassing various aspects including challenges and experiences associated with innovations in urban water cycle management. These papers straddle physical and policy research on implementation topics. Five papers fall in the area of systems modelling, two papers deal with design criteria issues of new and modified systems, one paper is of an experimental nature and another focuses on the impact of urban systems on the estuarine environment, while two papers deal with policy and risks. The papers included in this Special Issue emanated from a large number of submissions that were subjected to a thorough peer-review process. For this effort, we thank all the authors and reviewers that have contributed to this endeavour.