884 research outputs found
Assessing overall network structure in regional innovation policies: a case study of cluster policy in the West Midlands in the UK
Revisiting the theoretical roots of the key concepts of âembeddednessâ and ânetworksâ that underpin many recent regional innovation polices, this paper strives to achieve a more systematic understanding of the overall network structure of geographic agglomerations, which helps to form a more convincing model of regional development based on learning. This also helps to establish an analytical framework with indicators to assess the overall network structure in regional innovation policies. Employing the framework, the examination of cluster policy in the West Midlands highlights its weakness in addressing the overall cluster network structure and the contingent factors influencing the structure. The analysis suggests that there may be similar weaknesses in other regional innovation policies and the theories underpinning them as they share a common weakness in addressing the structural characteristics of overall networks
Privacy Amplification via Shuffling: Unified, Simplified, and Tightened
In decentralized settings, the shuffle model of differential privacy has
emerged as a promising alternative to the classical local model. Analyzing
privacy amplification via shuffling is a critical component in both
single-message and multi-message shuffle protocols. However, current methods
used in these two areas are distinct and specific, making them less convenient
for protocol designers and practitioners. In this work, we introduce
variation-ratio reduction as a unified framework for privacy amplification
analyses in the shuffle model. This framework utilizes total variation bounds
of local messages and probability ratio bounds of other users' blanket
messages, converting them to indistinguishable levels. Our results indicate
that the framework yields tighter bounds for both single-message and
multi-message encoders (e.g., with local DP, local metric DP, or general
multi-message randomizers). Specifically, for a broad range of local
randomizers having extremal probability design, our amplification bounds are
precisely tight. We also demonstrate that variation-ratio reduction is
well-suited for parallel composition in the shuffle model and results in
stricter privacy accounting for common sampling-based local randomizers. Our
experimental findings show that, compared to existing amplification bounds, our
numerical amplification bounds can save up to of the budget for
single-message protocols, of the budget for multi-message protocols, and
- of the budget for parallel composition. Additionally, our
implementation for numerical amplification bounds has only
complexity and is highly efficient in practice, taking just minutes for
users. The code for our implementation can be found at
\url{https://github.com/wangsw/PrivacyAmplification}.Comment: Code available at https://github.com/wangsw/PrivacyAmplificatio
Thermal-bioconvection in a non-scattering suspension of phototactic microorganisms
This article investigates the linear stability of thermal-bioconvection
within a suspension containing phototactic microorganisms heated from below. In
suspension, the upper surface is taken as stress-free, while the lower surface
is taken as rigid. The resulting eigenvalue problem, including the
bioconvection Rayleigh and thermal Rayleigh numbers, is resolved numerically.
Changes in the critical total intensity and Lewis number do not impact the
critical threshold of the thermal Rayleigh number; however, they notably
influence the critical bioconvection Rayleigh number. The critical total
intensity and Lewis number destabilize the suspension. It is observed that
heating from below enhances the instability of the layer. At higher
temperatures, Rayleigh-Bnard convection dominates bioconvection,
resulting in a single convection cell
Heating from Above in Non-scattering Suspensions: Phototactic Bioconvection under Collimated Irradiation
Examining phototactic bioconvection in non-scattering suspensions with upper
heating and collimated irradiation, this study delves into the intricate
dynamics influenced by light and microorganisms. The study focuses on the
linear stability of the basic state, examining neutral curves. The numerical
analysis involves solving a system of equations using the MATLAB bvp4c solver.
The investigation considers the impact of parameters, such as the thermal
Rayleigh number, critical total intensity, and Lewis number, on the critical
bioconvection Rayleigh number. As the critical total intensity varies, a
transition from a stationary to an oscillatory solution (and vice versa) is
observed. Phototactic microorganisms are incorporated into the model, and
results show how varying parameters affect convection patterns and stability.
The findings reveal interesting phenomena, including Hopf bifurcations and
limit cycles
Recommended from our members
Poly(oxime-ester) Vitrimers with Catalyst-Free Bond Exchange.
Vitrimers are network polymers that undergo associative bond exchange reactions in the condensed phase above a threshold temperature, dictated by the exchangeable bonds comprising the vitrimer. For vitrimers, chemistries reliant on poorly nucleophilic bond exchange partners (e.g., hydroxy-functionalized alkanes) or poorly electrophilic exchangeable bonds, catalysts are required to lower the threshold temperature, which is undesirable in that catalyst leaching or deactivation diminishes its influence over time and may compromise reuse. Here we show how to access catalyst-free bond exchange reactions in catalyst-dependent polyester vitrimers by obviating conventional ester bonds in favor of oxime-esters. Poly(oxime-ester) (POE) vitrimers are synthesized using thiol-ene click chemistry, affording high stretchability and malleability. POE vitrimers are readily recycled with little degradation of their initial mechanical properties, suggesting exciting opportunities for sustainable plastics
- âŠ