Currency Carry Trades - Prudent Investments or Just a Lottery?

Objectives: The objective of this study is to find out whether currency carry trades are prudent investments or a pure lottery. To consider currency carry trades as a prudent investment strategy they have to fulfill at least one of the following two criteria • The risk-adjusted performance of currency-carry trades should match or outperform the risk-adjusted performance of the equity indices. I.e. higher risk should be awarded with adequately higher profits. • Currency carry trades should be suitable as an alternative investment. I.e. the correlation between the stock market and the currency carry trade returns should be small or negative, especially in times of declining stock markets. Theoretical Framework: According to the Uncovered Interest Parity (UIP) a strategy that involves borrowing in a low yielding currency and investing it in a high yielding currency should not generate excess return. The high yielding currency is therefore expected to decrease. Thus previous studies all concluded that the UIP does not hold. Data and Methodology: The empirical part uses the one month interbank interest rate and the mid-rate for the exchange rate. The time horizon is from Jan. 1st 1993 until April 27th. We used three different methods to evaluate the risk-adjusted performance (Sharpe ratio, reward-to-VaR and conditional Sharpe ratio). To test the suitability as an alternative investment we applied the linear correlation and the exceedance correlation. Results and Findings: The findings support the research hypothesis that the riskadjusted measures of currency carry trading portfolio outperform the equity indices. Currency carry trades function as an alternative investment partly since criteria is not entirely fulfilled. In bear markets correlation is high, whereas in bull markets it is low

The Kapustin-Li formula revisited

We provide a new perspective on the Kapustin-Li formula for the duality pairing on the morphism complexes in the matrix factorization category of an isolated hypersurface singularity. In our context, the formula arises as an explicit description of a local duality isomorphism, obtained by using the basic perturbation lemma and Grothendieck residues. The non-degeneracy of the pairing becomes apparent in this setting. Further, we show that the pairing lifts to a Calabi-Yau structure on the matrix factorization category. This allows us to define topological quantum field theories with matrix factorizations as boundary conditions.Comment: 28 pages, 3 figures, comments welcom

Cosmic Microwave Background temperature and polarization anisotropies from the large-N limit of global defects

We determine the full C_l spectra and correlation functions of the temperature and polarization anisotropies in the CMB, generated by a source modeled by the large N limit of spontaneously broken global O(N)-theories. We point out a problem in the standard approach of treating the radiation-matter transition by interpolating the eigenvectors of the unequal-time correlators of the source energy-momentum tensor. This affects the CMB predictions from all type of cosmic defects. We propose a method to overcome this difficulty, and find that in the large-N global model that we study, differences in the final CMB power spectra amplitudes reach up to 25%, when compared to implementations of the eigenvector interpolation technique. We discuss as well how to optimally search for the contribution in the CMB from active sources such as cosmic defects, in experiments like Planck, COrE and PRISM.Comment: 16+4 pages, 13 figures (Version 2: minor changes to match published version in PRD

The local B-polarization of the CMB: a very sensitive probe of cosmic defects

We present a new and especially powerful signature of cosmic strings and other topological or non-topological defects in the polarization of the cosmic microwave background (CMB). We show that even if defects contribute 1% or less in the CMB temperature anisotropy spectrum, their signature in the local $\tilde{B}$-polarization correlation function at angular scales of tens of arc minutes is much larger than that due to gravitational waves from inflation, even if the latter contribute with a ratio as big as $r\simeq 0.1$ to the temperature anisotropies. We show that when going from non-local to local $\tilde{B}$-polarization, the ratio of the defect signal-to-noise with respect to the inflationary value increases by about an order of magnitude. Proposed B-polarization experiments, with a good sensitivity on arcminute scales, may either detect a contribution from topological defects produced after inflation or place stringent limits on them. Even Planck should be able to improve present constraints on defect models by at least an order of magnitude, to the level of \ep <10^{-7}. A future full-sky experiment like CMBpol, with polarization sensitivities of the order of $1\mu$K-arcmin, will be able to constrain the defect parameter \ep=Gv^2 to a few $\times10^{-9}$, depending on the defect model.Comment: Version Published in Physics Letters

The perception of strabismus by children and adults

Background: Visible strabismus has been shown to have adverse psychosocial consequences. It remains controversial if esotropia or exotropia is perceived more negatively. The aim of this study was to determine if esotropia or exotropia and the eye (side) in which strabismus is present are perceived differently. We also asked our adult participants: (1) if they thought visible strabismus should be corrected by surgery, (2) if they thought that strabismus surgery should only be to improve the cosmesis, and (3) if they thought that the surgery should be paid for by health insurance. Methods: One hundred adults and 61 children rated four photographs of a digitally altered picture of a boy and four of a girl, showing a large-angle esotropia or exotropia either in the left or on the right eye. The adults were additionally asked if a squint should be operated, if they considered strabismus surgery to be a cosmetic procedure, if in their opinion strabismus surgery should be covered by compulsory health insurance, and if children with strabismus are disadvantaged. Comparisons were performed using ANOVA and regression analysis. Results: Adults perceived a squinting right eye as more disturbing than a squinting left eye p  0.1 for each). Children also found that a squinting right eye is more disturbing (p < 0.001) than a left one. Additionally, children ranked esotropia worse than exotropia (p < 0.001). Neither age nor gender had an impact on the perception of strabismus by children. Of the adults, 94% would recommend surgery for all forms of strabismus, 18% thought that surgery is only cosmetic, and 94% found that health insurance should cover strabismus surgery for everybody. Problems of squinting children named by the adults included: being made fun of by other children (53%), problems with eyesight (39%), people looking strangely at them (21%), less acceptance by peers (17%), less self confidence (6%), problems judging distances (4%), and that they are perceived as less intelligent (3%). Conclusions: Adults and children rated a squinting right eye as worse compared to a left one. Children perceived esotropia as more disturbing than exotropia. Neither age, nor gender, nor the fact that the respondents have friends or family members with a squint, had an impact on this ranking. Almost all adults would correct all forms of strabismus, and think that surgery should be covered by compulsory health insuranc

Immune Cell Dynamics Unfolded by Single-Cell Technologies

The single-cell revolution is paving the way towards the molecular characterisation of every cell type in the human body, revealing relationships between cell types and states at high resolution. Changes in cellular phenotypes are particularly prevalent in the immune system and can be observed in its continuous remodelling up to adulthood, response to disease and development of immunological memory. In this review, we delve into the world of cellular dynamics of the immune system. We discuss current single-cell experimental and computational approaches in this area, giving insights into plasticity and commitment of cell fates. Finally, we provide an outlook on upcoming technological developments and predict how these will improve our understanding of the immune system