Algebraic generality versus arithmetic generality in the 1874 controversy between C. Jordan and L. Kronecker
This article revisits the 1874 controversy between Camille Jordan and Leopold Kronecker over two theorems, namely Jordan’s canonical forms and Karl Weierstrass’s elementary divisors theorem. In particular, it compares the perspectives of Jordan and Kronecker on generality and how their debate turned into an opposition over the algebraic or arithmetic nature of the ‘theory of forms’. It also examines the ways in which the various actors used the the categories of algebraic generality and arithmetic generality. After providing a background on the Jordan-Kronecker controversy, the article explains Jordan’s canonical reduction and Kronecker’s invariant computations in greater detail. It argues that Jordan and Kronecker aimed to ground the ‘theory of forms’ on new forms of generality, but could not agree on the types of generality and on the treatments of the general they were advocating.
D. Daghero, G.A. Ummarino, and R.S. Gonnelli
This article investigates the potential of the point contact Andreev reflection spectroscopy (PCARS) technique for measuring the symmetry of the energy gap and other key parameters of various 0-, 1-, and 2-dimensional superconducting systems. It begins with a brief description of PCARS, explaining what a point contact is and how it can be made and the conditions under which a PC is ballistic, as well as why and to what extent a PC between normal metals is spectroscopic. It then discusses the basics of Andreev reflection and the length scales in mesoscopic systems before considering the limits of applicability of PCARS for spectroscopy of ‘small’ superconductors. Finally, it reviews some examples of PCARS in quasi-0D, quasi-1D and quasi-2D superconductors.
Pontus Lurcock and Fabio Florindo
Antarctic climate changes have been reconstructed from ice and sediment cores and numerical models (which also predict future changes). Major ice sheets first appeared 34 million years ago (Ma) and fluctuated throughout the Oligocene, with an overall cooling trend. Ice volume more than doubled at the Oligocene-Miocene boundary. Fluctuating Miocene temperatures peaked at 17–14 Ma, followed by dramatic cooling. Cooling continued through the Pliocene and Pleistocene, with another major glacial expansion at 3–2 Ma. Several interacting drivers control Antarctic climate. On timescales of 10,000–100,000 years, insolation varies with orbital cycles, causing periodic climate variations. Opening of Southern Ocean gateways produced a circumpolar current that thermally isolated Antarctica. Declining atmospheric CO2 triggered Cenozoic glaciation. Antarctic glaciations affect global climate by lowering sea level, intensifying atmospheric circulation, and increasing planetary albedo. Ice sheets interact with ocean water, forming water masses that play a key role in global ocean circulation.
Joan Martí Molist
Volcanoes represent complex geological systems capable of generating many dangerous phenomena. To evaluate and manage volcanic risk, we need first to assess volcanic hazard (i.e., identify past volcanic system behavior to infer future behavior. This requires acquisition of all relevant geological and geophysical information, such as stratigraphic studies, geological mapping, sedimentological studies, petrologic studies, and structural studies. All this information is then used to elaborate eruption scenarios and hazard maps. Stratigraphic studies represent the main tool for the reconstruction of past activity of volcanoes over time periods exceeding their historical record. This review presents a systematic approach to volcanic hazard assessment, paying special attention to reconstruction of past eruptive history. It reviews concepts and methods most commonly used in long- and short-term hazard assessment and analyzes how they help address the various serious consequences derived from the occurrence (and nonoccurrence in some crisis alerts) of volcanic eruptions and related phenomena.
M. Stamenova and S. Sanvito
This article reviews recent advances towards the development of a truly atomistic time-dependent theory for spin-dynamics. The focus is on the s-d tight-binding model [where conduction electrons (s) are exchange-coupled to a number of classical spins (d)], including electrostatic corrections at the Hartree level, as the underlying electronic structure theory. In particular, the article considers one-dimensional (1D) magnetic atomic wires and their electronic structure, described by means of the s-d model. The discussion begins with an overview of the model spin Hamiltonian, followed by molecular-dynamics simulations of spin-wave dispersion in a s-d monoatomic chain and spin impurities in a non-magnetic chain. The current-induced motion in a magnetic domain wall (DW) is also explored, along with how an electric current can affect the magnetization landscape of a magnetic nano-object. The article concludes with an assessment of spin-motive force, and especially whether a driven magnetization dynamics can generate an electrical signal.
This article considers Josephson junction barriers, focusing on barriers made from insulators, metals, semiconductors, magnets, and nanowires. The main characteristic of Josephson junctions is the local reduction or even suppression of the critical current in the barrier. These barriers affect the static and dynamics properties of Josephson junctions, including coupling strength, ground state, phase damping, and tunability of the critical current. The article first provides an overview of the fundamental physics of Josephson junctions, with particular emphasis on the Josephson effect, before describing the properties of two coupled superconductors. It then discusses tunnel barriers, metallic barriers, semiconducting barriers, and magnetic barriers.
A. Burke, D. Carroll, Frank Torti, and S.V. Torti
This article examines the potential of bifunctional nanomaterials for the imaging and treatment of cancer. Several nanomaterials possess properties desirable for a cancer therapy and have been the subject of research as anticancer agents. Those that have received the most attention include encapsulated iron oxides, single- and multiwalled carbon nanotubes, gold nanorods and gold nanoshells. This article first considers thermal ablative therapy incancer, focusing on the mechanisms of thermotoxicity and thermoresistance before discussing a number of nanomaterials with applications for cancer treatment. In particular, it evaluates the use of nanomaterials in thermal therapy. It also looks at gold nanoshells and nanorods, taking into account their physical properties, and concludes with an assessment of iron-oxide nanoparticles and future directions for nanomaterials as multifunctional agents for cancer therapy.
P. Zrazhevskiy and X. Gao
This article discusses the use of bioconjugated quantum dots (QDs) for tumor molecular imaging and profiling. The need for personalized diagnostics and therapy is becoming apparent in all areas of medicine, and especially urgent and sought after in treating cancer. Mechanisms of cancerogenesis and cancer response to therapy remain poorly understood, thus precluding accurate cancer diagnosis, prognosis, and effective treatment. Accurate molecular profiling of individual tumors is one key to effective treatment. This article first considers the photophysical properties of QDs before reviewing the most common methods for engineering QD-based probes for biomedical applications, including water solubilization and bioconjugation approaches. It also describes a number of techniques for molecular imagingand profiling of tumors, ranging from QD-based multicolor flow cytometry and applications of QDs in high-resolution correlated fluorescence/electron microscopy, QD bioprobes for molecular profiling of tumor-tissue sections and microarrays, and QD-oligonucleotide bioconjugates for in-situ hybridization.
Aidan T. Brown and Pietro Cicuta
This article examines the properties of biological fluid interfaces and membranes, with particular emphasis on monolayers and bilayers. There are several examples of interfaces between biological fluids; the most relevant to human physiology are probably the liquid/air interfaces in the lungs and on the surface of the eyes. Both of these feature films with remarkable properties of compressibility and self-healing. After providing an overview of the constituent molecules of biological interfaces, this article reviews the current knowledge on surface films and membranes, giving context for their role in biology, but paying special attention to the basic physical ideas that underpin fundamental studies of in-vitro model systems. It also considers isolated membranes, characterized by tension, elasticity and viscous damping, as well as closed vesicles and cells where the membrane separates the cytoskeleton from the extracellular matrix.
Jean- Gaël Barbara
This article examines generality in biology by focusing on two French schools of anatomy: the discipline of anatomie générale that was founded in France in 1800 by Xavier Bichat and the one developed in the 1870s by Louis Ranvier at the Collège de France by means of microscopy. The works of Bichat and Ranvier involved the disciplines of anatomy and physiology. Bichat’s work, especially his research on tissues, is of interest for understanding which kind of concept of generality gained favor in the life sciences at the start of the nineteenth century. Ranvier’s later career sheds light on the ways that generality was searched for at the microscopic level and its significance in the discovery of real and minute biological objects. Following a discussion of Bichat and Ranvier’s anatomie générale, this article explores the two men’s interests in generality as an actor’s category.