pwc-archive/papers-with-abstracts huggingface dataset:
A Molecular Communication Perspective on Airborne Pathogen Transmission and Reception via Droplets Generated by Coughing and Sneezing
Authors: Fatih Gulec, Baris Atakan
Date: 2020-07-15 00:00:00

Infectious diseases spread via pathogens such as viruses and bacteria. Airborne pathogen transmission via droplets is an important mode for infectious diseases. In this paper, the spreading mechanism of infectious diseases by airborne pathogen transmission between two humans is modeled with a molecular communication perspective. An end-to-end system model which considers the pathogen-laden cough/sneeze droplets as the input and the infection state of the human as the output is proposed. This model uses the gravity, initial velocity and buoyancy for the propagation of droplets and a receiver model which considers the central part of the human face as the reception interface is proposed. Furthermore, the probability of infection for an uninfected human is derived by modeling the number of propagating droplets as a random process. The numerical results reveal that exposure time and sex of the human affect the probability of infection. In addition, the social distance for a horizontal cough should be at least 1.7 m and the safe coughing angle of a coughing human to infect less people should be less than -25$^\circ$.
A 0.5GHz 0.35mW LDO-Powered Constant-Slope Phase Interpolator with 0.22$\%$ INL
Authors: Ahmed Elnaqib, Hayate Okuhara, Taekwang Jang, Davide Rossi, Luca Benini
Date: 2020-07-15 00:00:00

Clock generators are an essential and critical building block of any communication link, whether it be wired or wireless, and they are increasingly critical given the push for lower I/O power and higher bandwidth in Systems-on-Chip (SoCs) for the Internet-of-Things (IoT). One recurrent issue with clock generators is multiple-phase generation, especially for low-power applications; several methods of phase generation have been proposed, one of which is phase interpolation. We propose a phase interpolator (PI) that employs the concept of constant-slope operation. Consequently, a low-power highly-linear operation is coupled with the wide dynamic range (i.e. phase wrapping) capabilities of a PI. Furthermore, the PI is powered by a low-dropout regulator (LDO) supporting fast transient operation. Implemented in 65-nm CMOS technology, it consumes 350$\mu$W at a 1.2-V supply and a 0.5-GHz clock; it achieves energy efficiency 4$\times$-15$\times$ lower than state-of-the-art (SoA) digital-to-time converters (DTCs) and an integral non-linearity (INL) of 2.5$\times$-3.1$\times$ better than SoA PIs, striking a good balance between linearity and energy efficiency.
3D Polarized Modulation: System Analysis and Performance
Authors: Pol Henarejos, Ana I. Pérez-Neira
Date: 2020-07-15 00:00:00

In this paper we present a novel modulation technique for dual polarization communication systems, which reduces the error rate compared with the existent schemes. This modulation places the symbols in a 3D constellation, rather than the classic approach of 2D. Adjusting the phase of these symbols depending on the information bits, we are able to increase the bit rate. Hence, the proposed scheme conveys information by selecting both polarization state and the phase of radiated electromagnetic wave. We also analyse the performance of 3D Polarized Modulation (PMod) for different constellation sizes and we obtain a curve of rate adaptation. Finally, we compare the proposed 3D PMod with other existing schemes such as single polarization Phase Shift Keying (PSK) and double polarization Vertical Bell Laboratories Layer Space-Time (V-BLAST), both carrying the same number of information bits. The results show that 3D PMod always outperforms all other schemes, except for low order modulation. Therefore, we can conclude that 3D PMod is an excellent candidate for medium and high modulation order transmissions.
Approximate XVA for European claims
Authors: Fabio Antonelli, Alessandro Ramponi, Sergio Scarlatti
Date: 2020-07-15 00:00:00
Tasks: Computational Efficiency

We consider the problem of computing the Value Adjustment of European contingent claims when default of either party is considered, possibly including also funding and collateralization requirements. As shown in Brigo et al. (\cite{BLPS}, \cite{BFP}), this leads to a more articulate variety of Value Adjustments ({XVA}) that introduce some nonlinear features. When exploiting a reduced-form approach for the default times, the adjusted price can be characterized as the solution to a possibly nonlinear Backward Stochastic Differential Equation (BSDE). The expectation representing the solution of the BSDE is usually quite hard to compute even in a Markovian setting, and one might resort either to the discretization of the Partial Differential Equation characterizing it or to Monte Carlo Simulations. Both choices are computationally very expensive and in this paper we suggest an approximation method based on an appropriate change of numeraire and on a Taylor's polynomial expansion when intensities are represented by means of affine processes correlated with the asset's price. The numerical discussion at the end of this work shows that, at least in the case of the CIR intensity model, even the simple first-order approximation has a remarkable computational efficiency.
The Isoline Tracking in Unknown Scalar Fields with Concentration Feedback
Date: 2020-07-15 00:00:00

The isoline tracking of this work is concerned with the control design for a
sensing vehicle to track a desired isoline of an unknown scalar field. To this
end, we propose a simple PI-like controller for a Dubins vehicle in the
GPS-denied environments. Our key idea lies in the design of a novel sliding
surface based error in the standard PI controller. For the circular field, we
show that the P-like controller can globally regulate the vehicle to the
desired isoline with the steady-state error that can be arbitrarily reduced by
increasing the P gain, and is eliminated by the PI-like controller. For any
smoothing field, the P-like controller is able to achieve the local regulation.
Then, it is extended to the cases of a single-integrator vehicle and a
doubleintegrator vehicle, respectively. Finally, the effectiveness and
advantages of our approaches are validated via simulations on the fixed-wing
UAV and quadrotor simulators.
The natural polyphenol fortunellin and its structural analogs are inhibitors of the SARS-CoV-2 main proteinase dimerization, as revealed by molecular simulation studies
Authors: Athanasios A. Panagiotopoulos, Danai-Maria Kotzampasi, George Sourvinos, Marilena Kampa, Stergios Pirintsos, Elias Castanas, Vangelis Daskalakis
Date: 2020-07-15 00:00:00

3CL-Pro (or M-Pro) is the SARS-CoV-2 main protease, acting as a homodimer, is responsible for the cleavage of the large polyprotein 1ab transcript in proteins acting on viral growth and replication. 3CL-Pro has been one of the most studied SARS-CoV-2 proteins and the subject of therapeutic interventions, targeting its catalytic domain. A number of drug candidates have been reported, including some natural products. Here, we investigated in silico, through binding and molecular dynamics simulations, the natural product space for the identification of candidates of 3CL-Pro dimerization inhibitors. We report that fortunellin (acacetin 7-O-neohesperidoside), a natural flavonoid O-glycoside, is a potent inhibitor of 3CL-Pro dimerization. A search of the ZINC natural products database identified another 16 related molecules, including apilin and rhoifolin, with interesting pharmacological properties. We propose that fortunellin and its structural analogs might be the basis of novel pharmaceuticals and dietary supplements against SARS-CoV-2 induced COVID-19 disease.
How Retroactivity Affects the Behavior of Incoherent Feed-Forward Loops
Authors: Junmin Wang, Calin Belta, Samuel A. Isaacson
Date: 2020-07-15 00:00:00
Tasks: Open-Ended Question Answering

An incoherent feed-forward loop (IFFL) is a network motif known for its ability to accelerate responses and generate pulses. Though functions of IFFLs are well studied, most previous computational analysis of IFFLs used ordinary differential equation (ODE) models where retroactivity, the effect downstream binding sites exert on the dynamics of an upstream transcription factor (TF), was not considered. It remains an open question to understand the behavior of IFFLs in contexts with high levels of retroactivity, e.g., in cells transformed/transfected with high-copy plasmids, or in eukaryotic cells where a TF binds to numerous high-affinity binding sites in addition to one or more functional target sites. Here we study the behavior of IFFLs by simulating and comparing ODE models with different levels of retroactivity. We find that increasing retroactivity in an IFFL can increase, decrease, or keep the network's response time and pulse amplitude constant. This suggests that increasing retroactivity, traditionally considered as an impediment to designing robust synthetic systems, could be exploited to improve the performance of IFFLs. We compare the behaviors of IFFLs to negative autoregulatory loops, another sign-sensitive response-accelerating network motif, and find that increasing retroactivity in a negative autoregulated circuit can only slow the response. The inability of a negative autoregulatory loop to flexibly handle retroactivity may have contributed to its lower abundance in eukaryotic relative to bacterial regulatory networks, a sharp contrast to the significant abundance of IFFLs in both cell types.
US faces endemic Covid-19 infections and deaths; ways to stop the pandemic
Date: 2020-07-21 00:00:00

A new epidemic model for Covid-19 has been constructed and simulated for
eight US states. The coefficients for this model, based on seven coupled
differential equations, are carefully evaluated against recorded data on cases
and deaths. These projections reveal that Covid-19 will become endemic,
spreading for more than two years. If stay-at-home orders are relaxed, most
states may experience a secondary peak in 2021. The number of Covid-19 deaths
could have been significantly lower in most states that opened up, if lockdowns
had been maintained. Additionally, our model predicts that decreasing contact
rate by 10%, or increasing testing by approximately 15%, or doubling lockdown
compliance (from the current $\sim$ 15%) will eradicate infections in Texas
within a year. Applied to the entire US, the predictions based on the current
situation indicate about 11 million total infections (including undetected), 8
million cumulative confirmed cases, and 630,000 cumulative deaths by November
1, 2020.
COVID-19 Induced Economic Uncertainty: A Comparison between the United Kingdom and the United States
Date: 2020-06-29 00:00:00

The purpose of this study is to investigate the effects of the COVID-19
pandemic on economic policy uncertainty in the US and the UK. The impact of the
increase in COVID-19 cases and deaths in the country, and the increase in the
number of cases and deaths outside the country may vary. To examine this, the
study employs bootstrap ARDL cointegration approach from March 8, 2020 to May
24, 2020. According to the bootstrap ARDL results, a long-run equilibrium
relationship is confirmed for five out of the 10 models. The long-term
coefficients obtained from the ARDL models suggest that an increase in COVID-19
cases and deaths outside of the UK and the US has a significant effect on
economic policy uncertainty. The US is more affected by the increase in the
number of COVID-19 cases. The UK, on the other hand, is more negatively
affected by the increase in the number of COVID-19 deaths outside the country
than the increase in the number of cases. Moreover, another important finding
from the study demonstrates that COVID-19 is a factor of great uncertainty for
both countries in the short-term.
Persistence in Financial Connectedness and Systemic Risk
Authors: Jozef Barunik, Michael Ellington
Date: 2020-07-14 00:00:00

This paper characterises dynamic linkages arising from shocks with heterogeneous degrees of persistence. Using frequency domain techniques, we introduce measures that identify smoothly varying links of a transitory and persistent nature. Our approach allows us to test for statistical differences in such dynamic links. We document substantial differences in transitory and persistent linkages among US financial industry volatilities, argue that they track heterogeneously persistent sources of systemic risk, and thus may serve as a useful tool for market participants.
A Graph Theoretic Approach to Power System Vulnerability Identification
Date: 2020-07-15 00:00:00

During major power system disturbances, when multiple component outages occur
in rapid succession, it becomes crucial to quickly identify the transmission
interconnections that have limited power transfer capability. Understanding the
impact of an outage on these critical interconnections (called saturated
cut-sets) is important for enhancing situational awareness and taking correct
actions. This paper proposes a new graph theoretic approach for analyzing
whether a contingency will create a saturated cut-set in a meshed power
network. A novel feature of the proposed algorithm is that it lowers the
solution time significantly making the approach viable for real-time
operations. It also indicates the minimum amount by which the power transfer
through the critical interconnections should be reduced so that
post-contingency saturation does not occur. Robustness of the proposed
algorithm for enhanced situational awareness is demonstrated using the IEEE-118
bus system as well as a 17,000+ bus model of the Western Interconnection (WI).
Comparisons made with different approaches for power system vulnerability
assessment prove the utility of the proposed scheme for aiding power system
operations during extreme exigencies.
A Fast Iterative Algorithm to design phase only sequences by minimizing the ISL metric
Authors: Surya Prakash Sankuru, Prabhu Babu
Date: 2020-07-15 00:00:00

Unimodular/Phase only sequence having impulse like aperiodic auto-correlation function plays a central role in the applications of RADAR, SONAR, Cryptography, and Wireless (CDMA) Communication Systems. In this paper, we propose a fast iterative algorithm to design phase only sequences of arbitrary lengths by minimizing the Integrated Side-lobe Level (ISL) metric, which is very closely related to the auto-correlation property of a sequence. The ISL minimization problem is solved iteratively by using the Majorization-Minimization (MM) technique, which ensures a monotonic convergence to the stationary minimum point. To highlight the performance of a proposed algorithm, we conduct the numerical experiments for different sequence lengths using different initializations and also compare them with the existing algorithms. Numerical simulations show that irrespective of the sequence length and initialization, the proposed algorithm is performing better than the state-of-the-art algorithms in terms of speed of convergence. We also show a computationally efficient way to implement our proposed algorithm by using the FFT and IFFT operations.
Slicing at the Physical Layer
Authors: Ana Perez-Neira, Miguel Angel Lagunas
Date: 2020-07-15 00:00:00

In next generation communications, slicing enables the selection and allocation of network resources to suit the requirements of very different vertical-driven use cases and applications. This work addresses fast real-time resource slicing by proposing the novel concept of slicing at the physical layer. To implement such a concept an orthonormal transform is devised that splits the Orthogonal Frequency Division Multiplex (OFDM) symbol into slices with ranked rate and latency. The advantage over any carrier or time segmentation of the original frame is that the proposed technique does not require channel information at transmission. Also, the frame overhead improves, and the decoding time is kept simple.
Social capital and resilience make an employee cooperate for coronavirus measures and lower his/her turnover intention
Date: 2020-07-23 00:00:00

An important theme is how to maximize the cooperation of employees when
dealing with crisis measures taken by the company. Therefore, to find out what
kind of employees have cooperated with the company's measures in the current
corona (COVID-19) crisis, and what effect the cooperation has had to these
employees/companies to get hints for preparing for the next crisis, the pass
analysis was carried out using awareness data obtained from a questionnaire
survey conducted on 2,973 employees of Japanese companies in China. The results
showed that employees with higher social capital and resilience were more
supportive of the company's measures against corona and that employees who were
more supportive of corona measures were less likely to leave their jobs.
However, regarding fatigue and anxiety about the corona felt by employees, it
was shown that it not only works to support cooperation in corona
countermeasures but also enhances the turnover intention. This means that just
by raising the anxiety of employees, even if a company achieves the short-term
goal of having them cooperate with the company's countermeasures against
corona, it may not reach the longer-term goal by making them increase their
intention to leave. It is important for employees to be aware of the crisis and
to fear it properly. But more than that, it should be possible for the company
to help employees stay resilient, build good relationships with them, and
increase their social capital to make them support crisis measurement of the
company most effectively while keeping their turnover intention low.
Frequency Regulation with Heterogeneous Energy Resources: A Realization using Distributed Control
Authors: Tor Anderson, Manasa Muralidharan, Priyank Srivastava, Hamed Valizadeh Haghi, Jorge Cortes, Jan Kleissl, Sonia Martinez, Byron Washom
Date: 2020-07-15 00:00:00

This paper presents one of the first real-life demonstrations of coordinated and distributed resource control for secondary frequency response in a power distribution grid. We conduct a series of tests with up to 69 heterogeneous active devices consisting of air handling units, unidirectional and bidirectional electric vehicle charging stations, a battery energy storage system, and 107 passive devices consisting of building loads and photovoltaic generators. Actuation commands for the test devices are obtained by solving an economic dispatch problem at every regulation instant using distributed ratio-consensus, primal-dual, and Newton-like algorithms. The distributed control setup consists of a set of Raspberry Pi end-points exchanging messages via an ethernet switch. The problem formulation minimizes the sum of device costs while tracking the setpoints provided by the system operator. We demonstrate accurate and fast real-time distributed computation of the optimization solution and effective tracking of the regulation signal by measuring physical device outputs over 40-minute time horizons. We also perform an economic benefit analysis which confirms eligibility to participate in an ancillary services market and demonstrates up to $53K of potential annual revenue for the selected population of devices.
Reconfigurable Waveguides Using Glide-Symmetric Bed of Nails: Design of an All-Metal Switch at Millimetre-Wave Band
Authors: Mohammad Bagheriasl, Julien Sarrazin, Guido Valerio
Date: 2020-07-15 00:00:00
Tasks: All

A reconfigurable millimeter-wave artificial waveguide using glide-symmetric pin-like contact-less metasurfaces is proposed in order to enable low loss and high-power-handling capability in switching operations. Thanks to the remarkable behaviour of glide symmetry, the meta-structures are used both as wide-band EBG material to confine the field in the guide and as low-dispersive guiding medium filling the guide itself. The reconfigurability is achieved by adjusting the displacement between the metasurfaces. A higher displacement enables propagation within the waveguide and a lower displacement suppresses it. A two-state reconfigurability is therefore designed, allowing the device to act as an on-off switch in the V-band. In particular, a dispersion analysis highlights the potential of such technology to achieve switching operating over a 55-66 GHz frequency range. A complete design including matching mechanism and WR15 feeding is also described and shown to exhibit a $S_{11}<-10$ dB bandwidth from 57.4 to 62.8 GHz. In the "off" state, the switch isolation is better than 65 dB and in the "on" state, the insertion losses are better than 0.7 dB within the entire operating frequency range. The isolation between two adjacent waveguides is also discussed to assess the integration of such a device within a switching network.
Global Representation of the Conditional LATE Model: A Separability Result
Authors: Yu-Chang Chen, Haitian Xie
Date: 2020-07-16 00:00:00

This paper studies the latent index representation of the conditional LATE model, making explicit the role of covariates in treatment selection. We find that if the directions of the monotonicity condition are the same across all values of the conditioning covariate, which is often assumed in the literature, then the treatment choice equation has to satisfy a separability condition between the instrument and the covariate. This global representation result establishes testable restrictions imposed on the way covariates enter the treatment choice equation. We later extend the representation theorem to incorporate multiple ordered levels of treatment.
Uncovering a factor-based expected return conditioning structure with Regression Trees jointly for many stocks
Authors: Vassilis Polimenis
Date: 2020-07-16 00:00:00
Tasks: regression

Given the success and almost universal acceptance of the simple linear regression three-factor model, it is interesting to analyze the informational content of the three factors in explaining stock returns when the analysis is allowed to consider non-linear dependencies between factors and stock returns. In order to better understand factor-based conditioning information with respect to expected stock returns within a regression tree setting, the analysis of stock returns is demonstrated using daily stock return data for 5 major US corporations. The first finding is that in all cases (solo and joint) the most informative factor is always the market excess return factor. Further, three major issues are discussed: a) the balance of a depth=1 tree as it relates to properties of the stock return distribution, b) the mechanism behind depth=1 tree balance in a joint regression tree and c) the dominant stock in a joint regression tree. It is shown that high skew values alone cannot explain the imbalance of the resulting tree split as stocks with pronounced skew may produce balanced tree splits.