A spectral survey of an ultra-hot Jupiter: Detection of metals in the transmission spectrum of KELT-9 b

Context: KELT-9 b exemplifies a newly emerging class of short-period gaseous exoplanets that tend to orbit hot, early type stars - termed ultra-hot Jupiters. The severe stellar irradiation heats their atmospheres to temperatures of $\sim 4,000$ K, similar to the photospheres of dwarf stars. Due to the absence of aerosols and complex molecular chemistry at such temperatures, these planets offer the potential of detailed chemical characterisation through transit and day-side spectroscopy. Studies of their chemical inventories may provide crucial constraints on their formation process and evolution history. Aims: To search the optical transmission spectrum of KELT-9 b for absorption lines by metals using the cross-correlation technique. Methods: We analyse 2 transits observed with the HARPS-N spectrograph. We use an isothermal equilibrium chemistry model to predict the transmission spectrum for each of the neutral and singly-ionized atoms with atomic numbers between 3 and 78. Of these, we identify the elements that are expected to have spectral lines in the visible wavelength range and use those as cross-correlation templates. Results: We detect absorption of Na I, Cr II, Sc II and Y II, and confirm previous detections of Mg I, Fe I, Fe II and Ti II. In addition, we find evidence of Ca I, Cr I, Co I, and Sr II that will require further observations to verify. The detected absorption lines are significantly deeper than model predictions, suggesting that material is transported to higher altitudes where the density is enhanced compared to a hydrostatic profile. There appears to be no significant blue-shift of the absorption spectrum due to a net day-to-night side wind. In particular, the strong Fe II feature is shifted by $0.18 \pm 0.27$ km~s$^{-1}$, consistent with zero. Using the orbital velocity of the planet we revise the steller and planetary masses and radii.Comment: Submitted to Astronomy and Astrophysics on January 18, 2019. Accepted on May 3, 2019. 26 pages, 11 figure

Chained Anomaly Detection Models for Federated Learning: An Intrusion Detection Case Study

The adoption of machine learning and deep learning is on the rise in the cybersecurity domain where these AI methods help strengthen traditional system monitoring and threat detection solutions. However, adversaries too are becoming more effective in concealing malicious behavior amongst large amounts of benign behavior data. To address the increasing time-to-detection of these stealthy attacks, interconnected and federated learning systems can improve the detection of malicious behavior by joining forces and pooling together monitoring data. The major challenge that we address in this work is that in a federated learning setup, an adversary has many more opportunities to poison one of the local machine learning models with malicious training samples, thereby influencing the outcome of the federated learning and evading detection. We present a solution where contributing parties in federated learning can be held accountable and have their model updates audited. We describe a permissioned blockchain-based federated learning method where incremental updates to an anomaly detection machine learning model are chained together on the distributed ledger. By integrating federated learning with blockchain technology, our solution supports the auditing of machine learning models without the necessity to centralize the training data. Experiments with a realistic intrusion detection use case and an autoencoder for anomaly detection illustrate that the increased complexity caused by blockchain technology has a limited performance impact on the federated learning, varying between 5 and 15%, while providing full transparency over the distributed training process of the neural network. Furthermore, our blockchain-based federated learning solution can be generalized and applied to more sophisticated neural network architectures and other use cases

Levy stable two-sided distributions: exact and explicit densities for asymmetric case

We study the one-dimensional Levy stable density distributions g(alpha, beta; x) for -infty < x < infty, for rational values of index alpha and the asymmetry parameter beta: alpha = l/k and beta = (l - 2r)/k, where l, k and r are positive integers such that 0 < l/k < 1 for 0 <= r <= l and 1 < l/k <= 2 for l-k <= r <= k. We treat both symmetric (beta = 0) and asymmetric (beta neq 0) cases. We furnish exact and explicit forms of g(alpha, beta; x) in terms of known functions for any admissible values of alpha and beta specified by a triple of integers k, l and r. We reproduce all the previously known exact results and we study analytically and graphically many new examples. We point out instances of experimental and statistical data that could be described by our solutions.Comment: 4 pages; 4 figure

Why fencers should bounce: a new method of movement to engage the stretch-shortening cycle

While teaching a heel first contact style of footwork in fencing (also referred to as toe contribution avoidance) is in keeping with long standing traditions, it is not conducive to today’s modern style of fast paced and explosive fencing. Equally, fencers towards the elite-end seem to be gradually adopting a more spring-based style, as their body progressively and organically transitions to “ball of the foot” based footwork, in order for them to fence competitively in the manner they have intuitively associated with success. Therefore, if from a young age fencers are taught to make full use of the stretch shortening cycle (SSC) via “bouncing” or simply by initiating movement via the ball of the foot, this will expedite the learning process. It will demonstrate to them how the SSC can be used to move at greater speed, cover greater distances when advancing, retreating and lunging, and conserve the much-needed energy required to compete over day long competitions. This paper details the mechanistic underpinnings of the SSC and its application to the modern day fencer

GCH1 deficiency activates brain innate immune response and impairs tyrosine hydroxylase homeostasis

The Parkinson’s disease (PD) risk gene GTP cyclohydrolase 1 (GCH1) catalyzes the rate-limiting step in tetrahydrobiopterin (BH4) synthesis, an essential cofactor in the synthesis of monoaminergic neurotransmitters. To investigate the mechanisms by which GCH1 deficiency may contribute to PD, we generated a loss of function zebrafish gch1 mutant (gch1-/-), using CRISPR/Cas technology. gch1-/- zebrafish develop marked monoaminergic neurotransmitter deficiencies by 5 dpf, movement deficits by 8 dpf and lethality by 12 dpf. Tyrosine hydroxylase protein levels were markedly reduced without loss of ascending dopaminergic (DAergic) neurons. L-Dopa treatment of gch1-/- larvae improved survival without ameliorating the motor phenotype. RNAseq of gch1-/- larval brain tissue identified highly upregulated transcripts involved in innate immune response. Subsequent experiments provided morphological and functional evidence of microglial activation in gch1-/-. The results of our study suggest that GCH1 deficiency may unmask early, subclinical parkinsonism and only indirectly contribute to neuronal cell death via immune-mediated mechanisms. Our work highlights the importance of functional validation for GWAS risk factors and further emphasises the important role of inflammation in the pathogenesis of PD

A Natural Experiment on Innovation Without Patents

Innovation occurs within a complex web of law. Of the myriad legal doctrines that affect innovation, the most directly relevant is intellectual property, particularly patent law. The United States Constitution, in Article I, Section 8, states a strong public policy goal for the granting of patents (and copyrights) to inventors: “To promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries.” Despite the Founding Fathers’ apparent faith in the societal benefits afforded by patent protection, a crescendo of recent critics have accused the patent system of complicating, slowing, or even thwarting innovation. Patents certainly present significant hurdles for open and user innovation. Moreover, von Hippel (2005) and Strandburg (2008) have demonstrated that user innovators, especially individuals, tend to be poorly served, and often harmed, by the patent system

Navigating 'the pit of doom': Affective responses to teaching 'grammar'

publication-status: Publishedtypes: ArticleThis article presents the outcomes of a study investigating current secondary English teachers' beliefs about grammar teaching, and illustrates the salience of teachers' emotional response to the issue. Interviews with 31 teachers reveal two discourses which frame the ways in which teachers express their feelings: a dominant discourse of grammar as threatening, reactionary and dull, and an oppositional discourse which positions grammar as inspiring, fascinating, and empowering. The influence of these discourses on practice is explored, along with examples of how attitudes can change as a result of participation in a research project. © 2012 National Association for the Teaching of English