The market for lemmings: The herding behavior of pension funds

Using a unique dataset that covers UK defined-benefit pension fund asset allocations over the past 25 years, we provide robust evidence that pension funds display strong herding behavior, and tend to herd in subgroups defined by fund size and sponsor type. We also show that, while pension funds tend to switch from equities to bonds as their liabilities mature, they mechanically rebalance their portfolios in the short term. Finally, we find that their price impact is neither persistent nor stabilizing, and that there are only small cross-sectional differences in returns across pension funds, consistent with their widespread herding behavior

Risky bank guarantees

© 2019 Elsevier B.V. Applying standard portfolio-sort techniques to bank asset returns for 15 countries from 2004 to 2018, we uncover a risk premium associated with implicit government guarantees. This risk premium is intimately tied to sovereign risk, suggesting that guaranteed banks, defined as those of particular importance to the national economy, inherit the risk of the guarantor. Indeed, this premium does not exist in safe-haven countries. We rationalize these findings with a model in which implicit government guarantees are risky in the sense that they provide protection that depends on the aggregate state of the economy

Circularly polarized light at the mirror: Caveats and opportunities

Moving from the simple concept that reflection onto a mirror surface changes the handedness of circularly polarized light, we describe what happens to the emergent polarization in two different cases after reflection on a back mirror. In the first case, a regular emitter is taken into account, where reflection has the effect to destroy the emergent polarization. In the second case, we show what could happen when a hypothetical apparently non-reciprocal emitting material undergoes a similar experiment. These simple concepts have important implications in the design of efficient circularly polarized emitting devices

Remarkable near-infrared chiroptical properties of chiral Yb, Tm and Er complexes

We carried out a study of absorption (CD) and emission (CPL) chiroptical properties in the NIR region of two sets of Yb, Tm and Er complexes. The two complexes include a D3 symmetric, [TMG-H+]3Ln(BINOLate)3 (Ln = Yb, Tm, Er; TMG = 1,1,3,3-tetramethylguanidine; BINOLate = 1,1'-bi-2-naphtholate), and a tetrakis, C4 symmetric, CsLn(hfbc)4 (Ln = Yb, Tm, Er; hfbc = 3-heptafluorobutylyrylcamphorate). The lanthanides studied gave access to three discrete energy domains, Yb (900-1040 nm), Tm (1180-1240 nm) and Er (1430-1600 nm) in which the chiroptical activity was assessed using gabs (and glum for Yb complexes). Exceptionally high discrimination between left and right circularly polarised light was observed, with values up to almost the theoretical maximum (±2)

Transfer of Axial Chirality to the Nanoscale Endows Carbon Nanodots with Circularly Polarized Luminescence

We report the synthesis, purification and characterization of chiral carbon nanodots starting from atropoisomeric precursors. The obtained atropoisomeric carbon nanodots are soluble in organic solvents and have good thermal stability, which are desirable features for technological applications. The synthetic protocol is robust, as it supports a number of variations in terms of molecular doping agents. Remarkably, the combination of axially chiral precursors and 1,4-benzoquinone as doping agent results in green-emissive carbon dots displaying circularly polarized luminescence. Dissymmetry factors of |3.5|×10−4 are obtained in solution, without the need of any additional element of chirality. Introducing axial chirality expands the strategies available to tailor the properties of carbon nanodots, paving the way for carbon nanoparticles that combine good processability in organic solvents with engineered advanced chiroptical properties

Efficient 1400-1600 nm Circularly Polarized Luminescence from a Tuned Chiral Erbium Complex

Novel chiral Er complexes based on both enantiomers of extended (i)PrPyBox (2,6-Bis[4-isopropyl-4,5-dihydrooxazol-2-yl)]pyridine) show strong near-infrared circularly polarized luminescence (CPL) within the 1400 to 1600 nm spectral region under 450 nm irradiation. CPL activity in this region, despite being particularly rare, would open the way to potential applications in the domain, e.g., of fiber-optic telecommunications and free-space long-distance optical communications employing circularly polarized light. Moreover, the long wavelength excitation is advantageous for applications in the field of (circularly polarized) microscopy and bioimaging

Two-Photon Circularly Polarized Luminescence of Chiral Eu Complexes

We report the synthesis of chiral lanthanide complexes with extended π conjugation for efficient circularly polarized luminescence (CPL) via two-photon excitation (2PE). The pyridine bis-oxazoline (PyBox) core provides the chiral Ln3+ environment, while the extension of the conjugated backbone through the pyridine 4-position with a phenylacetylene unit increases the two-photon absorption cross section. This work presents an important step toward the development of chiral systems displaying enhanced nonlinear optical properties, with potential applications in imaging and sensing, as well as in photodynamic therapy due to the selective excitation of molecules within a specific focal volume

From Mesocates to Helicates: Structural, Magnetic and Chiro-Optical Studies on Nickel(II) Supramolecular Assemblies Derived from Tetradentate Schiff Bases

The systematic reactions of a family of tetradentate pyridyl/imine and quinolyl/imine racemic or enantiopure Schiff bases with Ni(NO3)(2) or Ni(ClO4)(2) in the presence of sodium azide yielded, as a function of the starting racemic, chiral or achiral base, a set of chiral, meso or achiral complexes. In all cases, the compounds consist of two Ni-II cations linked by a double azido bridge in its end-on coordination mode. All the dimers exhibit a mesocate supramolecular structure and one of them, the unprecedented mix of helicate and mesocate in 2:1 ratio. The transition from mesocate to helicate conformation has been reached by tuning the flexibility of the central spacers of the Schiff bases and the size of the substituents. Electronic circular dichroism (ECD) studies have been performed for two pairs of enantiomers and interpreted by means of DFT calculations. Susceptibility measurements show a ferromagnetic coupling between the Ni-II cations mediated by the end-on azido bridges

Circularly Polarized Luminescence from New Heteroleptic Eu(III) and Tb(III) Complexes

The complexes [Eu(bpcd)(tta)], [Eu(bpcd)(Coum)], and [Tb(bpcd)(Coum)] [tta = 2-thenoyltrifluoroacetyl-acetonate, Coum = 3-acetyl-4-hydroxy-coumarin, and bpcd = N,N′-bis(2-pyridylmethyl)-trans-1,2-diaminocyclohexane-N,N′-diacetate] have been synthesized and characterized from photophysical and thermodynamic points of view. The optical and chiroptical properties of these complexes, such as the total luminescence, decay curves of the Ln(III) luminescence, electronic circular dichroism, and circularly polarized luminescence, have been investigated. Interestingly, the number of coordinated solvent (methanol) molecules is sensitive to the nature of the metal ion. This number, estimated by spectroscopy, is >1 for Eu(III)-based complexes and <1 for Tb(III)-based complexes. A possible explanation for this behavior is provided via the study of the minimum energy structure obtained by density functional theory (DFT) calculations on the model complexes of the diamagnetic Y(III) and La(III) counterparts [Y(bpcd)(tta)], [Y(bpcd)(Coum)], and [La(bpcd)(Coum)]. By time-dependent DFT calculations, estimation of donor-acceptor (D-A) distances and of the energy position of the S1and T1ligand excited states involved in the antenna effect was possible. These data are useful for rationalizing the different sensitization efficiencies (ηsens) of the antennae toward Eu(III) and Tb(III). The tta ligand is an optimal antenna for sensitizing Eu(III) luminescence, while the Coum ligand sensitizes better Tb(III) luminescence {φovl= 55%; ηsens≥ 55% for the [Tb(bpcd)(Coum)] complex}. Finally, for the [Eu(bpcd)(tta)] complex, a sizable value of glum(0.26) and a good quantum yield (26%) were measured

Brain-muscle communication prevents muscle aging by maintaining daily physiology

Muñoz-Cánoves, Pur