Advances in nanophotonics: ultrafast & ultrasensitive

In this tutorial on NanoPhotonics recent advances are highlighted with focus on near field optical methods, ultra-fast probing of single molecules and ultra-sensitive detection of individual non-fluorescent nanoparticles

A local view on single and coupled molecules

The paper focuses on a novel approach to reveal ultrafast dynamics in single molecules. The main strength of the approach is towards ultrafast processes in extended multi-chromophoric molecular assemblies. Excitonically coupled systems consisting of 2 and 3 rigidly linked perylene-diimide units in a head to tail configuration are studied. Superradiance and inhibited intramolecular decay are observed and discrete jumps in femtosecond response upon break-up of the strong coupling are revealed

How to Identify and Forecast Bull and Bear Markets?

The state of the equity market, often referred to as a bull or a bear market, is of key importance for financial decisions and economic analyses. Its latent nature has led to several methods to identify past and current states of the market and forecast future states. These methods encompass semi-parametric rule-based methods and parametric regime-switching models. We compare these methods by new statistical and economic measures that take into account the latent nature of the market state. The statistical measure is based directly on the predictions, while the economic mea- sure is based on the utility that results when a risk-averse agent uses the predictions in an investment decision. Our application of this framework to the S&P500 shows that rule-based methods are preferable for (in-sample) identification of the market state, but regime-switching models for (out-of-sample) forecasting. In-sample only the direction of the market matters, but for forecasting both means and volatilities of returns are important. Both the statistical and the economic measures indicate that these differences are significant

To pool or not to pool in hospitals: a theoretical and practical comparison for a radiotherapy outpatient department

This paper examines whether urgent and regular patients waiting for a consultation at a radiotherapy outpatient department should be pooled or not. Both queuing theory and discrete event simulation were applied to a realistic case study. The theoretical approach shows that pooling is not always beneficial with regard to the waiting times of urgent patients. Furthermore, the practical approach indicates that the separation of queues may require less capacity to meet the waiting time performance target for urgent as well as regular patients. The results seem to be of general interest for hospital

A “More-is-Better” heuristic in anticommons dilemmas: Psychological insights from a new anticommons bargaining game

In the present paper, we investigate how people make decisions when bargaining about complementary resources. When the ownership of such resources is fragmented, actors often fail to coordinate on efficient access, leading to an overall loss in social welfare; the tragedy of the anticommons. In a series of three experiments, in which we introduce a newly developed Anticommons Bargaining Game, we show that people tend to treat perfectly complementary resources as if they are non-complementary. Specifically, we demonstrate that both sellers and buyers of such resources used a more-is-better heuristic when determining their prices. That is, sellers who initially owned a larger part of the resource asked a higher price for their resource than sellers with a smaller part, even though only the combination of parts generated value for the buyer. Likewise, buyers offered more money to sellers with a larger part than to sellers with a smaller part. While this heuristic does not necessarily impede coordination, inequality in resources led to unequal monetary outcomes between the two sellers

Contagion as Domino Effect in Global Stock Markets

This paper shows that stock market contagion operates through a domino effect, where small crashes evolve into more severe crashes. Using a novel unifying framework we model the occurrence of local, regional and global crashes in terms of past occurrences of these different crashes and financial variables. We find convincing evidence that global crashes do not occur abruptly but are preceded by local and regional crashes. Additionally, interest rates, bond returns and volatility affect the probabilities of different crash types, indicating interdependence. We show that in forecasting global crashes our model outperforms a binomial model for global crashes only

Computational Screening of Tip and Stalk Cell Behavior Proposes a Role for Apelin Signaling in Sprout Progression

Angiogenesis involves the formation of new blood vessels by sprouting or splitting of existing blood vessels. During sprouting, a highly motile type of endothelial cell, called the tip cell, migrates from the blood vessels followed by stalk cells, an endothelial cell type that forms the body of the sprout. To get more insight into how tip cells contribute to angiogenesis, we extended an existing computational model of vascular network formation based on the cellular Potts model with tip and stalk differentiation, without making a priori assumptions about the differences between tip cells and stalk cells. To predict potential differences, we looked for parameter values that make tip cells (a) move to the sprout tip, and (b) change the morphology of the angiogenic networks. The screening predicted that if tip cells respond less effectively to an endothelial chemoattractant than stalk cells, they move to the tips of the sprouts, which impacts the morphology of the networks. A comparison of this model prediction with genes expressed differentially in tip and stalk cells revealed that the endothelial chemoattractant Apelin and its receptor APJ may match the model prediction. To test the model prediction we inhibited Apelin signaling in our model and in an \emph{in vitro} model of angiogenic sprouting, and found that in both cases inhibition of Apelin or of its receptor APJ reduces sprouting. Based on the prediction of the computational model, we propose that the differential expression of Apelin and APJ yields a "self-generated" gradient mechanisms that accelerates the extension of the sprout.Comment: 48 pages, 10 figures, 8 supplementary figures. Accepted for publication in PLoS ON

Time Variation in Asset Return Dependence: Strength or Structure?

The dependence between asset returns varies. Its strength can become stronger or weaker. Also, its structure can change, for example, when asymmetries related to bull and bear markets become more or less pronounced. To analyze these different types of variations, we develop a model that separately accommodates these changes. It combines a mixture of structurally different copulas with time variation. Our model shows both types of changes in the dependence between several equity market returns. Ignoring them leads to biases in risk measures. An underestimation of Value-at-Risk by maximum 15% occurs exactly when most harmful, during crisis periods

Consistent treatment of hydrophobicity in protein lattice models accounts for cold denaturation

The hydrophobic effect stabilizes the native structure of proteins by minimizing the unfavourable interactions between hydrophobic residues and water through the formation of a hydrophobic core. Here we include the entropic and enthalpic contributions of the hydrophobic effect explicitly in an implicit solvent model. This allows us to capture two important effects: a length-scale dependence and a temperature dependence for the solvation of a hydrophobic particle. This consistent treatment of the hydrophobic effect explains cold denaturation and heat capacity measurements of solvated proteins.Comment: Added and corrected references for design procedure in main text (p. 2) and in Supplemental Information (p. 8

Social Ball: An immersive research paradigm to study social ostracism

We introduce “Social Ball,” a new research paradigm to study ostracism via an online ball tossing game based on Cyberball (Williams & Jarvis, 2006) designed with both researchers and participants in mind. For researchers, the game incorporates a variety of features which are easily accessible from the software’s interface. Some of these features have already been studied with Cyberball (e.g., tossing different objects) but some are novel (e.g., end-game communication or hand-waving during the game). From the participants’ perspective, the game was designed to be more visually and socially immersive to create a more video-game- like online environment. We discuss two previous implementations. Study 1 showed that Social Ball successfully induced need threat and negative affect among ostracized (vs included) participants (n = 247). Study 2 empirically demonstrated how a new feature of the game (i.e., hand-waving) can be used to answer various questions. The results suggested that people waved their hands to varying degrees yet the frequency of which was not associated with post game need satisfaction (n = 2578). Besides describing the features of the game, we also provide a configuration manual and an annotated R code (both as online supplementary materials) to make the paradigm and associated analyses more accessible, and in turn, to stimulate further research. In our discussion, we elaborate on the various ways in which Social Ball can contribute to the understanding of belonging and ostracism