346 research outputs found
Testing Partial Instrument Monotonicity
When multi-dimensional instruments are used to identify and estimate causal
effects, the monotonicity condition may not hold due to heterogeneity in the
population. Under a partial monotonicity condition, which only requires the
monotonicity to hold for each instrument separately holding all the other
instruments fixed, the 2SLS estimand can still be a positively weighted average
of LATEs. In this paper, we provide a simple nonparametric test for partial
instrument monotonicity. We demonstrate the good finite sample properties of
the test through Monte Carlo simulations. We then apply the test to monetary
incentives and distance from results centers as instruments for the knowledge
of HIV status
Implications of supermassive neutron stars for the form of the equation of state of hybrid stars
The observations of PSR J0952-0607 and the second object in GW190814 event
indicate the possible existence of supermassive neutron stars. In this work, by
using the Constant-Sound-Speed (CSS) parametrization to describe the equation
of state (EOS) of quark matter, the constraints on the EOS parameters from
supermassive hybrid stars are investigated through the Maxwell and Gibbs
constructions. It is shown that to support a supermassive hybrid star, a lower
transition energy density, a smaller energy density discontinuity and a higher
sound speed of quark matter are favored. For the constructed hybrid star EOS
model, the maximum mass of the corresponding hybrid stars will not meet the
lower mass limit of the second object in GW190814 if the energy density
discontinuity takes a value higher than . Moreover, it
is confirmed that the supermassive neutron star observation can also rule out
the existence of twin stars as a supermassive hybrid star requires a relatively
small energy density discontinuity. Finally, we give a rough estimate of the
lower limit of the dimensionless tidal deformability of neutron stars which
ranges from 2 to 3.Comment: 12 pages, 5 figure
Numerical Security Analysis of Three-State Quantum Key Distribution Protocol with Realistic Devices
Quantum key distribution (QKD) is a secure communication method that utilizes
the principles of quantum mechanics to establish secret keys. The central task
in the study of QKD is to prove security in the presence of an eavesdropper
with unlimited computational power. In this work, we successfully solve a
long-standing open question of the security analysis for the three-state QKD
protocol with realistic devices, i,e, the weak coherent state source. We prove
the existence of the squashing model for the measurement settings in the
three-state protocol. This enables the reduction of measurement dimensionality,
allowing for key rate computations using the numerical approach. We conduct
numerical simulations to evaluate the key rate performance. The simulation
results show that we achieve a communication distance of up to 200 km.Comment: 14 pages, 5 figure
Hybrid algorithm simulating non-equilibrium steady states of an open quantum system
Non-equilibrium steady states are a focal point of research in the study of
open quantum systems. Previous variational algorithms for searching these
steady states have suffered from resource-intensive implementations due to
vectorization or purification of the system density matrix, requiring large
qubit resources and long-range coupling. In this work, we present a novel
variational quantum algorithm that efficiently searches for non-equilibrium
steady states by simulating the operator-sum form of the Lindblad equation. By
introducing the technique of random measurement, we are able to estimate the
nonlinear cost function while reducing the required qubit resources by half
compared to previous methods. Additionally, we prove the existence of the
parameter shift rule in our variational algorithm, enabling efficient updates
of circuit parameters using gradient-based classical algorithms. To demonstrate
the performance of our algorithm, we conduct simulations for dissipative
quantum transverse Ising and Heisenberg models, achieving highly accurate
results. Our approach offers a promising solution for effectively addressing
non-equilibrium steady state problems while overcoming computational
limitations and implementation challenges.Comment: 8 pages, 4 figure
The TIPE Model for Teaching Technology-Based Entrepreneurship
It is widely believed that the technology-based entrepreneurship has great potential to increase wealth and competitiveness. Researchers believe that Technology-based Entrepreneurship Education (TEE) may raise students’ awareness about the technology entrepreneurship and the opportunities for technology commercialization. However, TEE has a relatively shorter history than conventional entrepreneurship education in business schools and there are fewer cases. This paper will use a revised 4W1H framework to review existing models of TEE and then present the TIPE model that has been implemented at a university in Hong Kong since 2001 for master students. Educational and policy implications are explored finally
A hybrid algorithm for quadratically constrained quadratic optimization problems
Quadratically Constrained Quadratic Programs (QCQPs) are an important class
of optimization problems with diverse real-world applications. In this work, we
propose a variational quantum algorithm for general QCQPs. By encoding the
variables on the amplitude of a quantum state, the requirement of the qubit
number scales logarithmically with the dimension of the variables, which makes
our algorithm suitable for current quantum devices. Using the primal-dual
interior-point method in classical optimization, we can deal with general
quadratic constraints. Our numerical experiments on typical QCQP problems,
including Max-Cut and optimal power flow problems, demonstrate a better
performance of our hybrid algorithm over the classical counterparts.Comment: 8 pages, 3 figure
The Simultaneous Impact of Supplier and Customer Involvement on New Product Performance
The recall rates of various products these years have triggered a new round of interests in the impacts of supplier involvement (SI) and customer involvement (CI) on new product performance (NPP). However, existing literature looks at either SI or CI but not both. Most supply chain management papers focus on SI and NPP while research in marketing field focuses on CI and NPP. Additionally, the NPP has not been elaborated into detail dimensions in these previous studies. This research investigates the impact of both SI and CI on the three dimensions of NPP, namely new product quality and reliability, time to market and product innovativeness. The research was based on the data from over 600 manufacturers in 21 countries. Structural equation modeling (SEM) is used to test the simultaneous impact of SI and CI on NPP. The results show that SI influences all the three dimensions of NPP while CI influences quality and reliability. The research also reveals that companies pay more attention to CI than SI. It seems that more efforts in both academic and practical fields are needed to enhance SI in relation to NPD. The research suggests that both SI and CI should be implemented in new product development process. It is not a two-party issue but a three-party-issue
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