Separating Skill from Luck in REIT Mutual Funds

This study uses a bootstrap methodology to explicitly distinguish between skill and luck for 80 Real Estate Investment Trust Mutual Funds in the period January 1995 to May 2008. The methodology successfully captures non-normality in the idiosyncratic risk of the funds. Using unconditional, beta conditional and alpha-beta conditional estimation models, the results indicate that all but one fund demonstrates poor skill. Tests of robustness show that this finding is largely invariant to REIT market conditions and maturity.

Separating skill from luck in REIT mutual funds

This study uses a bootstrap methodology to explicitly distinguish between skill and luck for 80 Real Estate Investment Trust Mutual Funds in the period January 1995 to May 2008. The methodology successfully captures non-normality in the idiosyncratic risk of the funds. Using unconditional, beta conditional and alpha-beta conditional estimation models, the results indicate that all but one fund demonstrates poor skill. Tests of robustness show that this finding is largely invariant to REIT market conditions and maturity

Recreating Wonder Woman's invisible plane: A quantitative analysis of UAV visual signature manipulation via counterillumination

This study analyzes the effectiveness of an optical camouflage method called counterillumination and its effectiveness on an unmanned aerial vehicle (UAV). Counterillumination is achieved by emitting blue light on the bottom of the UAV to blend into the sky. Preliminary results are underwhelming, but design modifications can be made to improve the performance of the system. Further testing is required in order to collect any relevant data. Due to the COVID-19 Pandemic, unfortunately, this project could not be completed.Lew Wentz FoundationMechanical and Aerospace Engineerin

A Nonstationary Model of Newborn EEG

The detection of seizure in the newborn is a critical aspect of neurological research. Current automatic detection techniques are difficult to assess due to the problems associated with acquiring and labelling newborn electroencephalogram (EEG) data. A realistic model for newborn EEG would allow confident development, assessment and comparison of these detection techniques. This paper presents a model for newborn EEG that accounts for its self-similar and non-stationary nature. The model consists of background and seizure sub-models. The newborn EEG background model is based on the short-time power spectrum with a time-varying power law. The relationship between the fractal dimension and the power law of a power spectrum is utilized for accurate estimation of the short-time power law exponent. The newborn EEG seizure model is based on a well-known time-frequency signal model. This model addresses all significant time-frequency characteristics of newborn EEG seizure which include; multiple components or harmonics, piecewise linear instantaneous frequency laws and harmonic amplitude modulation. Estimates of the parameters of both models are shown to be random and are modelled using the data from a total of 500 background epochs and 204 seizure epochs. The newborn EEG background and seizure models are validated against real newborn EEG data using the correlation coefficient. The results show that the output of the proposed models has a higher correlation with real newborn EEG than currently accepted models (a 10% and 38% improvement for background and seizure models, respectively)

Development of a selection to recover improved DNA ligase enzymes during directed evolution

DNA ligases are essential enzymes used in many molecular biology applications. Of particular note, they are important enzymes in next generation sequencing (NGS) technologies. The improved speed, efficiency, and affordability of NGS over Sanger sequencing has greatly expanded the applications of DNA sequencing. In most NGS technologies ligase enzymes play a crucial role, for instance in ligating adaptors onto sequence fragments during sample preparation. This key step requires a blunt-ended ligation reaction, with highly efficient ligases required in order to create a sample library of high quality. The current go-to enzyme is T4 DNA ligase, which has not evolved in Nature to perform blunt ended ligations, and as such has relatively poor levels of activity when compared to other substrates. There is therefore potential to improve upon this enzyme and engineer a ligase that is more efficient with blunt-ended substrates. We have developed a novel function-based directed evolution selection to evolve blunt-ended ligases that have greater catalytic efficiency. The basis for this approach is the over-expression of a ligase enzyme variant which is then incubated with a linearised plasmid encoding for that same ligase variant. More efficient ligases will ligate the plasmid encoding for their own gene variant more efficiently (in a blunt-ended ligation), and so greater numbers of the circularised plasmid will be produced. Through successive rounds of transformation, amplification and ligation the most improved enzyme variants are enriched. This selection approach is being used to evaluate a panel of ligase variants in order to identify the best ligases for blunt-ended ligation applications. Please click Additional Files below to see the full abstract

Direct resummation of the leading renormalons in inclusive semileptonic B decay

We present a Borel resummation method for the QCD corrections in inclusive, charmless, semileptonic B meson decay. The renormalon contributions are resummed to all orders by employing a bilocal expansion of the Borel transform that accurately accounts for the first infrared renormalons in the Borel plane. The renormalons in the pole mass and the QCD expansion are resummed separately, and a precise relation is obtained between a properly defined pole mass and the ${\bar {\rm MS}}$ mass. The inclusive decay rate is calculated to three loop order using an estimate of the yet unknown NNLO coefficient.Comment: 10 pages,3 figures, version to appear in Phys. Lett.

Acute kidney injury in patients undergoing elective primary lower limb arthroplasty

Acknowledgements The authors would like to thank Abhi Punit for his contributions in data collection towards the above article Funding No funds, grants or other support was received.Open access via springer agreementPeer reviewedPublisher PD

Genetic control of Aedes aegypti: data-driven modelling to assess the effect of releasing different life stages and the potential for long-term suppression

Background Control of the world’s most important vector-borne viral disease, dengue, is a high priority. A lack of vaccines or effective vector control methods means that novel solutions to disease control are essential. The release of male insects carrying a dominant lethal (RIDL) is one such approach that could be employed to control Aedes aegypti. To maximise the potential of RIDL control, optimum release strategies for transgenic mosquitoes are needed. The use of field data to parameterise models allowing comparisons of the release of different life-stages is presented together with recommendations for effective long-term suppression of a wild Ae. aegypti population. Methods A compartmental, deterministic model was designed and fitted to data from large-scale pupal mark release recapture (MRR) field experiments to determine the dynamics of a pupal release. Pulsed releases of adults, pupae or a combination of the two were simulated. The relative ability of different release methods to suppress a simulated wild population was examined and methods to maintain long-term suppression of a population explored. Results The pupal model produced a good fit to field data from pupal MRR experiments. Simulations using this model indicated that adult-only releases outperform pupal-only or combined releases when releases are frequent. When releases were less frequent pupal-only or combined releases were a more effective method of distributing the insects. The rate at which pupae eclose and emerge from release devices had a large influence on the relative efficacy of pupal releases. The combined release approach allows long-term suppression to be maintained with smaller low-frequency releases than adult- or pupal-only release methods. Conclusions Maximising the public health benefits of RIDL-based vector control will involve optimising all stages of the control programme. The release strategy can profoundly affect the outcome of a control effort. Adult-only, pupal-only and combined releases all have relative advantages in certain situations. This study successfully integrates field data with mathematical models to provide insight into which release strategies are best suited to different scenarios. Recommendations on effective approaches to achieve long-term suppression of a wild population using combined releases of adults and pupae are provided

Scale Setting in QCD and the Momentum Flow in Feynman Diagrams

We present a formalism to evaluate QCD diagrams with a single virtual gluon using a running coupling constant at the vertices. This method, which corresponds to an all-order resummation of certain terms in a perturbative series, provides a description of the momentum flow through the gluon propagator. It can be viewed as a generalization of the scale-setting prescription of Brodsky, Lepage and Mackenzie to all orders in perturbation theory. In particular, the approach can be used to investigate why in some cases the ``typical'' momenta in a loop diagram are different from the ``natural'' scale of the process. It offers an intuitive understanding of the appearance of infrared renormalons in perturbation theory and their connection to the rate of convergence of a perturbative series. Moreover, it allows one to separate short- and long-distance contributions by introducing a hard factorization scale. Several applications to one- and two-scale problems are discussed in detail.Comment: eqs.(51) and (83) corrected, minor typographic changes mad