1,177 research outputs found
Level Set Based Hippocampus Segmentation in MR Images with Improved Initialization Using Region Growing
The hippocampus has been known as one of the most important structures referred to as Alzheimer’s disease and other neurological disorders. However, segmentation of the hippocampus from MR images is still a challenging task due to its small size, complex shape, low contrast, and discontinuous boundaries. For the accurate and efficient detection of the hippocampus, a new image segmentation method based on adaptive region growing and level set algorithm is proposed. Firstly, adaptive region growing and morphological operations are performed in the target regions and its output is used for the initial contour of level set evolution method. Then, an improved edge-based level set method utilizing global Gaussian distributions with different means and variances is developed to implement the accurate segmentation. Finally, gradient descent method is adopted to get the minimization of the energy equation. As proved by experiment results, the proposed method can ideally extract the contours of the hippocampus that are very close to manual segmentation drawn by specialists
Stock Volatility Prediction Based on Transformer Model Using Mixed-Frequency Data
With the increasing volume of high-frequency data in the information age,
both challenges and opportunities arise in the prediction of stock volatility.
On one hand, the outcome of prediction using tradition method combining stock
technical and macroeconomic indicators still leaves room for improvement; on
the other hand, macroeconomic indicators and peoples' search record on those
search engines affecting their interested topics will intuitively have an
impact on the stock volatility. For the convenience of assessment of the
influence of these indicators, macroeconomic indicators and stock technical
indicators are then grouped into objective factors, while Baidu search indices
implying people's interested topics are defined as subjective factors. To align
different frequency data, we introduce GARCH-MIDAS model. After mixing all the
above data, we then feed them into Transformer model as part of the training
data. Our experiments show that this model outperforms the baselines in terms
of mean square error. The adaption of both types of data under Transformer
model significantly reduces the mean square error from 1.00 to 0.86.Comment: Accepted by the 7th APWeb-WAIM International Joint Conference on Web
and Big Data. (APWeb 2023
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Genome Composition and Divergence of the Novel Coronavirus (2019-nCoV) Originating in China.
An in-depth annotation of the newly discovered coronavirus (2019-nCoV) genome has revealed differences between 2019-nCoV and severe acute respiratory syndrome (SARS) or SARS-like coronaviruses. A systematic comparison identified 380 amino acid substitutions between these coronaviruses, which may have caused functional and pathogenic divergence of 2019-nCoV
Alcohol Consumption and Risk of Common Autoimmune Inflammatory Diseases—Evidence From a Large-Scale Genetic Analysis Totaling 1 Million Individuals
Purpose: Observational studies have suggested a protective effect of alcohol intake with autoimmune disorders, which was not supported by Mendelian randomization (MR) analyses that used only a few (<20) instrumental variables.Methods: We systemically interrogated a putative causal relationship between alcohol consumption and four common autoimmune disorders, using summary-level data from the largest genome-wide association study (GWAS) conducted on inflammatory bowel disease (IBD), rheumatoid arthritis (RA), multiple sclerosis (MS), and systemic lupus erythematosus (SLE). We quantified the genetic correlation to examine a shared genetic similarity. We constructed a strong instrument using 99 genetic variants associated with drinks per week and applied several two-sample MR methods. We additionally incorporated excessive drinking as reflected by alcohol use disorder identification test score.Results: We observed a negatively shared genetic basis between alcohol intake and autoimmune disorders, although none was significant (rg = −0.07 to −0.02). For most disorders, genetically predicted alcohol consumption was associated with a slightly (10–25%) decreased risk of onset, yet these associations were not significant. Meta-analyzing across RA, MS, and IBD, the three Th1-related disorders yielded to a marginally significantly reduced effect [OR = 0.70 (0.51–0.95), P = 0.02]. Excessive drinking did not appear to reduce the risk of autoimmune disorders.Conclusions: With its greatly augmented sample size and substantially improved statistical power, our MR study does not convincingly support a beneficial role of alcohol consumption in each individual autoimmune disorder. Future studies may be designed to replicate our findings and to understand a causal effect on disease prognosis
Biodegradable PEG-poly(ω-pentadecalactone- co - p -dioxanone) nanoparticles for enhanced and sustained drug delivery to treat brain tumors
Intracranial delivery of therapeutic agents is limited by penetration beyond the blood-brain barrier (BBB)
and rapid metabolism of the drugs that are delivered. Convection-enhanced delivery (CED) of drugloaded
nanoparticles (NPs) provides for local administration, control of distribution, and sustained
drug release. While some investigators have shown that repeated CED procedures are possible, longer
periods of sustained release could eliminate the need for repeated infusions, which would enhance
safety and translatability of the approach. Here, we demonstrate that nanoparticles formed from
poly(ethylene glycol)-poly(u-pentadecalactone-co-p-dioxanone) block copolymers [PEG-poly(PDL-co-
DO)] are highly efficient nanocarriers that provide long-term release: small nanoparticles (less than
100 nm in diameter) continuously released a radiosensitizer (VE822) over a period of several weeks
in vitro, provided widespread intracranial drug distribution during CED, and yielded significant drug
retention within the brain for over 1 week. One advantage of PEG-poly(PDL-co-DO) nanoparticles is that
hydrophobicity can be tuned by adjusting the ratio of hydrophobic PDL to hydrophilic DO monomers,
thus making it possible to achieve a wide range of drug release rates and drug distribution profiles. When
administered by CED to rats with intracranial RG2 tumors, and combined with a 5-day course of fractionated
radiation therapy, VE822-loaded PEG-poly(PDL-co-DO) NPs significantly prolonged survival
when compared to free VE822. Thus, PEG-poly(PDL-co-DO) NPs represent a new type of versatile
nanocarrier system with potential for sustained intracranial delivery of therapeutic agents to treat brain
tumors
Climate change : strategies for mitigation and adaptation
The sustainability of life on Earth is under increasing threat due to humaninduced climate change. This perilous change in the Earth's climate is caused by increases in carbon dioxide and other greenhouse gases in the atmosphere, primarily due to emissions associated with burning fossil fuels. Over the next two to three decades, the effects of climate change, such as heatwaves, wildfires, droughts, storms, and floods, are expected to worsen, posing greater risks to human health and global stability. These trends call for the implementation of mitigation and adaptation strategies. Pollution and environmental degradation exacerbate existing problems and make people and nature more susceptible to the effects of climate change. In this review, we examine the current state of global climate change from different perspectives. We summarize evidence of climate change in Earth’s spheres, discuss emission pathways and drivers of climate change, and analyze the impact of climate change on environmental and human health. We also explore strategies for climate change mitigation and adaptation and highlight key challenges for reversing and adapting to global climate change
Green Pathways for the Enzymatic Synthesis of Furan-Based Polyesters and Polyamides
The attention towards the utilization of sustainable feedstocks for polymer synthesis has grown exponentially in recent years. One of the spotlighted monomers derived from renewable resources is 2,5-furandicarboxylic acid (FDCA), one of the most promising bio-based monomers, due to its resemblance to petroleum-based terephthalic acid. Very interesting synthetic routes using this monomer have been reported in the last two decades. Combining the use of bio-based monomers and non-toxic chemicals via enzymatic polymerizations can lead to a robust and favorable approach towards a greener technology of bio-based polymer production. In this chapter, a brief introduction to FDCA-based monomers and enzymatic polymerizations is given, particularly focusing on furan-based polymers and their polymerization. In addition, an outline of the recent developments in the field of enzymatic polymerizations is discussed. </p
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