3 research outputs found
Online Detection Of Supply Chain Network Disruptions Using Sequential Change-Point Detection for Hawkes Processes
In this paper, we attempt to detect an inflection or change-point resulting
from the Covid-19 pandemic on supply chain data received from a large furniture
company. To accomplish this, we utilize a modified CUSUM (Cumulative Sum)
procedure on the company's spatial-temporal order data as well as a GLR
(Generalized Likelihood Ratio) based method. We model the order data using the
Hawkes Process Network, a multi-dimensional self and mutually exciting point
process, by discretizing the spatial data and treating each order as an event
that has a corresponding node and time. We apply the methodologies on the
company's most ordered item on a national scale and perform a deep dive into a
single state. Because the item was ordered infrequently in the state compared
to the nation, this approach allows us to show efficacy upon different degrees
of data sparsity. Furthermore, it showcases use potential across differing
levels of spatial detail.Comment: Accepted to AAAI 2023 Workshop on Graphs and more Complex structures
for Learning and Reasonin
Early Detection of COVID-19 Hotspots Using Spatio-Temporal Data
Recently, the Centers for Disease Control and Prevention (CDC) has worked
with other federal agencies to identify counties with increasing coronavirus
disease 2019 (COVID-19) incidence (hotspots) and offers support to local health
departments to limit the spread of the disease. Understanding the
spatio-temporal dynamics of hotspot events is of great importance to support
policy decisions and prevent large-scale outbreaks. This paper presents a
spatio-temporal Bayesian framework for early detection of COVID-19 hotspots (at
the county level) in the United States. We assume both the observed number of
cases and hotspots depend on a class of latent random variables, which encode
the underlying spatio-temporal dynamics of the transmission of COVID-19. Such
latent variables follow a zero-mean Gaussian process, whose covariance is
specified by a non-stationary kernel function. The most salient feature of our
kernel function is that deep neural networks are introduced to enhance the
model's representative power while still enjoying the interpretability of the
kernel. We derive a sparse model and fit the model using a variational learning
strategy to circumvent the computational intractability for large data sets.
Our model demonstrates better interpretability and superior hotspot-detection
performance compared to other baseline methods
Dacarbazine-Loaded Hollow Mesoporous Silica Nanoparticles Grafted with Folic Acid for Enhancing Antimetastatic Melanoma Response
Dacarbazine
(DTIC) is one of the most important chemotherapeutic
agents for the treatment of melanoma; however, its poor solubility,
photosensitivity, instability, and serious toxicity to normal cells
limit its clinical applications. In this article, we present a rationally
designed nanocarrier based on hollow mesoporous silica nanoparticles
(HMSNs) for the encapsulation and targeted release of DTIC for eradicating
melanoma. The nanocarrier (DTIC@HMLBFs) is prepared by modifying HMSNs
with carboxyl groups to enhance the loading of DTIC, followed by further
enveloping of folic acid-grafted liposomes, which act as a melanoma
active target for controlled and targeted drug release. In vitro,
DTIC@HMLBFs exhibited the strongest cytotoxicity to melanoma cells
compared with DTIC@HMSNs and free DTIC. The in vivo investigations
demonstrate that the rationally designed nanocarrier loaded with DTIC
achieves significant improvement against lung metastasis of melanoma
via targeting melanoma cells and tumor-associated macrophages. This
study provides a promising platform for the design and fabrication
of multifunctional nanomedicines, which are potentially useful for
the treatment of melanoma