1,191 research outputs found
A stochastic user-operator assignment game for microtransit service evaluation: A case study of Kussbus in Luxembourg
This paper proposes a stochastic variant of the stable matching model from
Rasulkhani and Chow [1] which allows microtransit operators to evaluate their
operation policy and resource allocations. The proposed model takes into
account the stochastic nature of users' travel utility perception, resulting in
a probabilistic stable operation cost allocation outcome to design ticket price
and ridership forecasting. We applied the model for the operation policy
evaluation of a microtransit service in Luxembourg and its border area. The
methodology for the model parameters estimation and calibration is developed.
The results provide useful insights for the operator and the government to
improve the ridership of the service.Comment: arXiv admin note: substantial text overlap with arXiv:1912.0198
Surface-immobilised micelles via cucurbit[8]uril-rotaxanes for solvent-induced burst release.
The fabrication, characterisation and controlled burst release of naphthol-functionalised micellar (NFM) nanostructures, which were grafted onto gold surfaces through cucurbit[8]uril (CB[8]) mediated host-guest interactions are described. NFMs undergo a facile change in morphology from micelles to diblock copolymers in direct response to exposure to organic solvents, including tetrahydrofuran (THF), toluene and chloroform. This induced transition in conformation lends itself to potential applications including nanocarriers for triggered burst-release of guest molecules. Nile Red was investigated as a NFM encapsulated model hydrophobic cargo inside the surface-attached micelles, which could be fully released upon exposure to THF as measured by both atomic force microscopy and UV/vis spectroscopy.C. Hu thanks BP for supporting this work and Hughes Hall
College Cambridge for a student scholarship. Y. Zheng was
supported by an ERC starting investigator grant (ASPiRe
240629). Z. Yu is supported by an EPSRC grant (EP/H046593/1).This is the final version. It first appeared at http://pubs.rsc.org/en/Content/ArticleLanding/2015/CC/C5CC00121H#!divAbstract
Clustered Federated Learning based on Nonconvex Pairwise Fusion
This study investigates clustered federated learning (FL), one of the
formulations of FL with non-i.i.d. data, where the devices are partitioned into
clusters and each cluster optimally fits its data with a localized model. We
propose a novel clustered FL framework, which applies a nonconvex penalty to
pairwise differences of parameters. This framework can automatically identify
clusters without a priori knowledge of the number of clusters and the set of
devices in each cluster. To implement the proposed framework, we develop a
novel clustered FL method called FPFC. Advancing from the standard ADMM, our
method is implemented in parallel, updates only a subset of devices at each
communication round, and allows each participating device to perform a variable
amount of work. This greatly reduces the communication cost while
simultaneously preserving privacy, making it practical for FL. We also propose
a new warmup strategy for hyperparameter tuning under FL settings and consider
the asynchronous variant of FPFC (asyncFPFC). Theoretically, we provide
convergence guarantees of FPFC for general nonconvex losses and establish the
statistical convergence rate under a linear model with squared loss. Our
extensive experiments demonstrate the advantages of FPFC over existing methods.Comment: 46 pages, 9 figure
Does urbanization have spatial spillover effect on poverty reduction: empirical evidence from rural China
In light of a scarcity of research on the spatial effects of urbanization
on poverty reduction, this study uses panel data on 30 provinces
in China from 2009 to 2019 to construct a system of indices
to assess poverty that spans the four dimensions of the economy,
education, health, and living. We use the spatial autocorrelation
test and the spatial Durbin model (SDM) to analyze the spatial
effects of urbanization on poverty reduction in these different
dimensions. The main conclusions are as follows: (a) China’s
urbanization has the characteristics of spatial aggregation and a
spatial spillover effect. (b) Different dimensions of poverty had
the attributes of spatial agglomeration, and Moran’s index of a
reduction in economic poverty was the highest. Under the SDM,
the different dimensions of poverty also showed a significant
positive spatial correlation. (c) Urbanization has a significant effect
on poverty reduction along the dimensions of the economy, education,
and living, but has little effect on reducing health poverty.
It has a spatial spillover effect on poverty reduction in economic
and living contexts. (d) There were spatial differences in the effect
of urbanization on relieving economic and living-related poverty
Interfacial assembly of dendritic microcapsules with host-guest chemistry.
The self-assembly of nanoscale materials to form hierarchically ordered structures promises new opportunities in drug delivery, as well as magnetic materials and devices. Herein, we report a simple means to promote the self-assembly of two polymers with functional groups at a water-chloroform interface using microfluidic technology. Two polymeric layers can be assembled and disassembled at the droplet interface using the efficiency of cucurbit[8]uril (CB[8]) host-guest supramolecular chemistry. The microcapsules produced are extremely monodisperse in size and can encapsulate target molecules in a robust, well-defined manner. In addition, we exploit a dendritic copolymer architecture to trap a small hydrophilic molecule in the microcapsule skin as cargo. This demonstrates not only the ability to encapsulate small molecules but also the ability to orthogonally store both hydrophilic and hydrophobic cargos within a single microcapsule. The interfacially assembled supramolecular microcapsules can benefit from the diversity of polymeric materials, allowing for fine control over the microcapsule properties.This work was supported by the Engineering Physical Sciences Research Council, Institutional Sponsorship 2012-University of Cambridge EP/K503496/1 and the Translational Grant EP/H046593/1; Dr. Yu Zheng and Dr. Richard M. Parker were also funded from the Starting Investigator grant ASPiRe (No. 240629) from the European Research Council and the Isaac Newton Trust research grant No. 13.7(c).This is the accepted manuscript of a paper published in Nature Communications (Zheng Y, Yu Z, Parker RM, Wu Y, Abell C, Scherman OA, Nature Communications 2014, 5, 5772, doi:10.1038/ncomms6772)
A user-operator assignment game with heterogeneous user groups for empirical evaluation of a microtransit service in Luxembourg
We tackle the problem of evaluating the impact of different operation
policies on the performance of a microtransit service. This study is the first
empirical application using the stable matching modeling framework to evaluate
different operation cost allocation and pricing mechanisms on microtransit
service. We extend the deterministic stable matching model to a stochastic
reliability-based one to consider user's heterogeneous perceptions of utility
on the service routes. The proposed model is applied to the evaluation of
Kussbus microtransit service in Luxembourg. We found that the current Kussbus
operation is not a stable outcome. By reducing their route operating costs of
50%, it is expected to increase the ridership of 10%. If Kussbus can reduce
in-vehicle travel time on their own by 20%, they can significantly increase
profit several folds from the baseline
Headwater streams contain amounts of heavy metal in an alpine forest in the upper reaches of the Yangtze River
Headwater streams are an essential link in the source and sink dynamics of heavy metals between terrestrial and aquatic ecosystems and are also critically important for downstream ecosystem processes and water quality. However, there is little available information about headwater streams. Therefore, the stream storage and distribution patterns of Cd, Pb, Ni, Cr, Cu, Mn and Zn were investigated in ten headwater streams of an Alpine forest located in the upper Yangtze River during the rainy season. The results indicated that the heavy metal storage per unit area of the investigated streams was as follows: 0.95 mg·m-2 for Cd, 8.36 mg m-2 for Pb, 1.98 mg m-2 for Ni, 136.98 mg m-2 for Cr, 9.29 mg m-2 for Cu, 433.39 mg m-2 for Mn and 29.07 mg m-2 for Zn; while the heavy metal storage per unit area of the catchment was as follows: 1.19 mg hm-2 for Cd, 10.47 mg hm-2 for Pb, 2.48 mg hm-2 for Ni, 171.62 mg hm-2 for Cr, 11.64 mg hm-2 for Cu, 542.99 mg hm-2 for Mn and 36.42 mg hm-2 for Zn. Headwater streams present remarkable potential for contamination, and plant debris from riparian forests may be the most important source of heavy metals, while the stream sediment acts as a significant sink for heavy metals. These results provide new perspectives and data for understanding the ecological links between alpine forests and watersheds
See, Plan, Predict: Language-guided Cognitive Planning with Video Prediction
Cognitive planning is the structural decomposition of complex tasks into a
sequence of future behaviors. In the computational setting, performing
cognitive planning entails grounding plans and concepts in one or more
modalities in order to leverage them for low level control. Since real-world
tasks are often described in natural language, we devise a cognitive planning
algorithm via language-guided video prediction. Current video prediction models
do not support conditioning on natural language instructions. Therefore, we
propose a new video prediction architecture which leverages the power of
pre-trained transformers.The network is endowed with the ability to ground
concepts based on natural language input with generalization to unseen objects.
We demonstrate the effectiveness of this approach on a new simulation dataset,
where each task is defined by a high-level action described in natural
language. Our experiments compare our method again stone video generation
baseline without planning or action grounding and showcase significant
improvements. Our ablation studies highlight an improved generalization to
unseen objects that natural language embeddings offer to concept grounding
ability, as well as the importance of planning towards visual "imagination" of
a task
The effects of Tbx15 and Pax1 on facial and other physical morphology in mice
DNA variants in or close to the human TBX15 and PAX1 genes have been repeatedly associated with facial morphology in independent genome‐wide association studies, while their functional roles in determining facial morphology remain to be understood. We generated Tbx15 knockout (Tbx15 (−/−)) and Pax1 knockout (Pax1 (−/−)) mice by applying the one‐step CRISPR/Cas9 method. A total of 75 adult mice were used for subsequent phenotype analysis, including 38 Tbx15 mice (10 homozygous Tbx15 (−/−), 18 heterozygous Tbx15 (+/−), 10 wild‐type Tbx15 (+/+) WT littermates) and 37 Pax1 mice (12 homozygous Pax1 (−/−), 15 heterozygous Pax1 (+/−), 10 Pax1 (+/+) WT littermates). Facial and other physical morphological phenotypes were obtained from three‐dimensional (3D) images acquired with the HandySCAN BLACK scanner. Compared to WT littermates, the Tbx15 (−/−) mutant mice had significantly shorter faces (p = 1.08E‐8, R(2) = 0.61) and their ears were in a significantly lower position (p = 3.54E‐8, R(2) = 0.62) manifesting a “droopy ear” characteristic. Besides these face alternations, Tbx15 (−/−) mutant mice displayed significantly lower weight as well as shorter body and limb length. Pax1 (−/−) mutant mice showed significantly longer noses (p = 1.14E‐5, R(2) = 0.46) relative to WT littermates, but otherwise displayed less obvious morphological alterations than Tbx15 (−/−) mutant mice did. We provide the first direct functional evidence that two well‐known and replicated human face genes, Tbx15 and Pax1, impact facial and other body morphology in mice. The general agreement between our findings in knock‐out mice with those from previous GWASs suggests that the functional evidence we established here in mice may also be relevant in humans
Photo2Relief: Let Human in the Photograph Stand Out
In this paper, we propose a technique for making humans in photographs
protrude like reliefs. Unlike previous methods which mostly focus on the face
and head, our method aims to generate art works that describe the whole body
activity of the character. One challenge is that there is no ground-truth for
supervised deep learning. We introduce a sigmoid variant function to manipulate
gradients tactfully and train our neural networks by equipping with a loss
function defined in gradient domain. The second challenge is that actual
photographs often across different light conditions. We used image-based
rendering technique to address this challenge and acquire rendering images and
depth data under different lighting conditions. To make a clear division of
labor in network modules, a two-scale architecture is proposed to create
high-quality relief from a single photograph. Extensive experimental results on
a variety of scenes show that our method is a highly effective solution for
generating digital 2.5D artwork from photographs.Comment: 10 pages, 11 figure
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