A case study of quark-gluon discrimination at NNLL' in comparison to parton showers

Predictions for our ability to distinguish quark and gluon jets vary by more than a factor of two between different parton showers. We study this problem using analytic resummed predictions for the thrust event shape up to NNLL' using $e^+e^- \to Z \to q \bar q$ and $e^+e^- \to H \to gg$ as proxies for quark and gluon jets. We account for hadronization effects through a nonperturbative shape function, and include an estimate of both perturbative and hadronization uncertainties. In contrast to previous studies, we find reasonable agreement between our results and predictions from both Pythia and Herwig parton showers. We find that this is due to a noticeable improvement in the description of gluon jets in the newest Herwig 7.1 compared to previous versions.Comment: 10 pages, 5 figure

Predicting Three Types of Freezing of Gait Events Using Deep Learning Models

Freezing of gait is a Parkinson's Disease symptom that episodically inflicts a patient with the inability to step or turn while walking. While medical experts have discovered various triggers and alleviating actions for freezing of gait, the underlying causes and prediction models are still being explored today. Current freezing of gait prediction models that utilize machine learning achieve high sensitivity and specificity in freezing of gait predictions based on time-series data; however, these models lack specifications on the type of freezing of gait events. We develop various deep learning models using the transformer encoder architecture plus Bidirectional LSTM layers and different feature sets to predict the three different types of freezing of gait events. The best performing model achieves a score of 0.427 on testing data, which would rank top 5 in Kaggle's Freezing of Gait prediction competition, hosted by THE MICHAEL J. FOX FOUNDATION. However, we also recognize overfitting in training data that could be potentially improved through pseudo labelling on additional data and model architecture simplification.Comment: 5 page

Temperature-Dependent Electron-Electron Interaction in Graphene on SrTiO3

The electron band structure of graphene on SrTiO3 substrate has been investigated as a function of temperature. The high-resolution angle-resolved photoemission study reveals that the spectral width at Fermi energy and the Fermi velocity of graphene on SrTiO3 are comparable to those of graphene on a BN substrate. Near the charge neutrality, the energy-momentum dispersion of graphene exhibits a strong deviation from the well-known linearity, which is magnified as temperature decreases. Such modification resembles the characteristics of enhanced electron-electron interaction. Our results not only suggest that SrTiO3 can be a plausible candidate as a substrate material for applications in graphene-based electronics, but also provide a possible route towards the realization of a new type of strongly correlated electron phases in the prototypical two-dimensional system via the manipulation of temperature and a proper choice of dielectric substrates.Comment: 16 pages, 3 figure

Light Curves from an Expanding Relativistic Jet

We perform fully relativistic hydrodynamic simulations of the deceleration and lateral expansion of a relativistic jet as it expands into an ambient medium. The hydrodynamic calculations use a 2D adaptive mesh refinement (AMR) code, which provides adequate resolution of the thin shell of matter behind the shock. We find that the sideways propagation is different than predicted by simple analytic models. The physical conditions at the sides of the jet are found to be significantly different than at the front of the jet, and most of the emission occurs within the initial opening angle of the jet. The light curves, as seen by observers at different viewing angles with respect to the jet axis, are then calculated assuming synchrotron emission. For an observer along the jet axis, we find a sharp achromatic `jet break' in the light curve at frequencies above the typical synchrotron frequency, at $t_{jet}\approx 5.8(E_{52}/n_1)^{1/3}(\theta_0/0.2)^{8/3}$ days, while the temporal decay index $\alpha$ ($F_{\nu}\propto t^{\alpha}$) after the break is steeper than $-p$ ($\alpha=-2.85$ for $p=2.5$). At larger viewing angles $t_{jet}$ increases and the jet break becomes smoother.Comment: 3 pages, 2 figures, oral presentation on 2nd Rome Workshop on Gamma-Ray Bursts in the Afterglow Er

Gapped Nearly Free-Standing Graphene on an SiC(0001) Substrate Induced by Manganese Atoms

The electron band structure of manganese-adsorbed graphene on an SiC(0001) substrate has been studied using angle-resolved photoemission spectroscopy. Upon introducing manganese atoms, the conduction band of graphene completely disappears and the valence band maximum is observed at 0.4 eV below Fermi energy. At the same time, the slope of the valence band decreases, approaching the electron band structure calculated using the local density approximation method. While the former provides experimental evidence of the formation of nearly free-standing graphene on an SiC substrate, concomitant with a metal-to-insulator transition, the latter suggests that its electronic correlations can be modified by foreign atoms. These results pave the way for promising device applications using graphene that is semiconducting and charge neutral.Comment: 16 pages, 3 figure

Prevalence and heritability of handedness in a Hong Kong Chinese twin and singleton sample

Funding: Research Grants Council of the Hong Kong Special Administration Region (CUHK8/CRF/13G & C4054-17WF), by an internal grant entitled “Reading Development in Chinese and in English: Genetics and Neuroscience Correlates”(4930703) from The Chinese University of Hong Kong (CM is the PI on both grants), by a Hong Kong: Scotland Collaborative Research Partnership award from the Hong Kong Grants Council (CMis the PI for the Hong Kong side) and the Scottish Funding Council (SP is the PI for the Scotland side). It was additionally funded by an International Exchange Kan Tongo Po Visiting Fellowship to SP. SP is a Royal Society University Research Fellow.Background Left-handedness prevalence has been consistently reported at around 10% with heritability estimates at around 25%. Higher left-handedness prevalence has been reported in males and in twins. Lower prevalence has been reported in Asia, but it remains unclear whether this is due to biological or cultural factors. Most studies are based on samples with European ethnicities and using the preferred hand for writing as key assessment. Here, we investigated handedness in a sample of Chinese school children in Hong Kong, including 426 singletons and 205 pairs of twins, using both the Edinburgh Handedness Inventory and Pegboard Task. Results Based on a binary definition of writing hand, we found a higher prevalence of left-handedness (8%) than what was previously reported in Asian datasets. We found no evidence of increased left-handedness in twins, but our results were in line with previous findings showing that males have a higher tendency to be left-handed than females. Heritability was similar for both hand preference (21%) and laterality indexes (22%). However, these two handedness measures present only a moderate correlation (.42) and appear to be underpinned by different genetic factors. Conclusion In summary, we report new reference data for an ethnic group usually underrepresented in the literature. Our heritability analysis supports the idea that different measures will capture different components of handedness and, as a consequence, datasets assessed with heterogeneous criteria are not easily combined or compared.PreprintPublisher PDFPeer reviewe