112 research outputs found
Joint sum-max limit for a class of long-range dependent processes with heavy tails
We consider a class of stationary processes exhibiting both long-range
dependence and heavy tails. Separate limit theorems for sums and for extremes
have been established recently in literature with novel objects appearing in
the limits. In this article, we establish the joint sum-max limit theorems for
this class of processes. In the finite-variance case, the limit consists of two
independent components: a fractional Brownian motion arising from the sum, and
a long-range dependent random sup measure arising from the maximum. In the
infinite-variance case, we obtain in the limit two dependent components: a
stable process and a random sup measure whose dependence structure is described
through the local time and range of a stable subordinator. For establishing the
limit theorem in the latter case, we also develop a joint convergence result
for the local time and range of subordinators, which may be of independent
interest.Comment: 26 page
Green credit policy and corporate climate risk exposure
This paper investigates the effects of green credit policies on corporate climate risk exposure and the underlying mechanisms in China. Our results show that after the introduction of green credit policies, enterprises in polluting industries experienced a notable decline in climate risk compared to their counterparts. Further analysis reveals that the effectiveness of green credit policies in mitigating corporate climate risks can be attributed to their capacity to foster green technological innovation, refine investment strategies, facilitate the process of digitalization, and enhance the visibility of environmental issues among analysts. Moreover, we find that climate risk shaping policies vary significantly among firms, with particularly pronounced impacts on financially constrained and state-owned enterprises. This study provides critical insights for policymakers aiming to address climate challenges and bolster green financial strategies
Placenta-Derived Mesenchymal Stromal Cells: Modulation of Immunity and Inflammation
As an organ generally discarded after a normal full-term birth, the placenta is one of the most studied organs from the cellular standpoint. The placenta contains large numbers of immune cells, stem cells, and stromal cells. These cell types spurred the field of regenerative medicine by catalyzing the establishment of cord blood banks and hematopoietic stem cell reconstitution in the treatment of many diseases including cancer. Previously, many scientific articles and reviews have focused on the production, phenotype, and functional characterization of bone marrow-derived mesenchymal stromal cells. In this chapter, the focus will be solely on the biology, phenotype, and functional characterization of placenta-derived stromal cells. Modulation of the immune response, including T cell proliferation, dendritic cell maturation, and monocyte differentiation by placenta-derived stromal cells, will be discussed. This chapter will span in vitro functional analyses, animal models highlighting the in vitro data culminating in a summary of current clinical activity
Is synthetic data from generative models ready for image recognition?
Recent text-to-image generation models have shown promising results in
generating high-fidelity photo-realistic images. Though the results are
astonishing to human eyes, how applicable these generated images are for
recognition tasks remains under-explored. In this work, we extensively study
whether and how synthetic images generated from state-of-the-art text-to-image
generation models can be used for image recognition tasks, and focus on two
perspectives: synthetic data for improving classification models in data-scarce
settings (i.e. zero-shot and few-shot), and synthetic data for large-scale
model pre-training for transfer learning. We showcase the powerfulness and
shortcomings of synthetic data from existing generative models, and propose
strategies for better applying synthetic data for recognition tasks. Code:
https://github.com/CVMI-Lab/SyntheticData.Comment: ICLR 2023, spotligh
Experimental Study of Granular Clogging in Two-Dimensional Hopper
We experimentally investigate the clogging process of granular materials in a
two-dimensional hopper, and present a self-consistent physical mechanism of
clogging based on preformed dynamic chain structures in the flow. We found that
these chain structures follow a specific modified restricted random walk, and
clogging occurs when they are mechanically stable enough to withstand the flow
fluctuations, resulting in the formation of an arch at the outlet. We introduce
a simple model which can explain the clogging probability by incorporating an
analytical expression for chain formation and its transition into an arch. Our
results provide insight into the microscopic mechanism of clogging in hopper
flow.Comment: 22 pages, 8 figure
Incorporating mesopelagic fish into the evaluation of conservation areas for marine living resources under climate change scenarios
Mesopelagic fish (meso-fish) are central species within the Southern Ocean (SO). However, their ecosystem role and adaptive capacity to climate change are rarely integrated into marine protected area (MPAs) assessments. This is a pity given their importance as crucial prey and predators in food webs, coupled with the impacts of climate change. Here, we estimate the habitat distribution of nine meso-fish using an ensemble model approach (MAXENT, random forest, and boosted regression tree). Four climate model simulations were used to project their distribution under two representative concentration pathways (RCP4.5 and RCP8.5) for short-term (2006–2055) and long-term (2050–2099) periods. In addition, we assess the ecological representativeness of established and proposed MPAs under climate change scenarios using meso-fish as indicator species. Our models show that all species shift poleward in the future. Lanternfishes (family Myctophidae) are predicted to migrate poleward more than other families (Paralepididae, Nototheniidae, Bathylagidae, and Gonostomatidae). In comparison, lanternfishes were projected to increase habitat area in the eastern SO but lose area in the western SO; the opposite was projected for species in other families. Important areas (IAs) of meso-fish are mainly distributed near the Antarctic Peninsula and East Antarctica. Proposed MPAs cover 23% of IAs at present and 38% of IAs in the future (RCP8.5, long-term future). Many IAs of meso-fish still need to be included in MPA proposals, such as the Prydz Bay and the seas around the Antarctic Peninsula. Our results provide a framework for designing new MPAs incorporating climate change adaptation strategies for MPA management
Pressure-induced superconductivity in kagome single crystal Pd3P2S8
Kagome lattice offers unique opportunities for the exploration of unusual
quantum states of correlated electrons. Here, we report on the observation of
superconductivity in a kagome single crystal Pd3P2S8 when a semiconducting to
metallic transition is driven by pressure. High-pressure resistance
measurements show that the metallization and superconductivity are
simultaneously observed at about 11 GPa. With increasing pressure, the
superconducting critical temperature Tc is monotonously enhanced from 2.6 K to
a maximum 7.7 K at ~52 GPa. Interestingly, superconductivity retains when the
pressure is fully released. Synchrotron XRD and Raman experiments consistently
evidence that the emergence of superconductivity is accompanied with an
amorphization and the retainability of superconductivity upon decompression can
be attributed to the irreversibility of the amorphization
Multiomic profiling reveals metabolic alterations mediating aberrant platelet activity and inflammation in myeloproliferative neoplasms
Platelets from patients with myeloproliferative neoplasms (MPNs) exhibit a hyperreactive phenotype. Here, we found elevated P-selectin exposure and platelet-leukocyte aggregates indicating activation of platelets from essential thrombocythemia (ET) patients. Single-cell RNA-seq analysis of primary samples revealed significant enrichment of transcripts related to platelet activation, mTOR, and oxidative phosphorylation in ET patient platelets. These observations were validated via proteomic profiling. Platelet metabolomics revealed distinct metabolic phenotypes consisting of elevated ATP generation accompanied by increases in the levels of multiple intermediates of the tricarboxylic acid cycle, but lower α-ketoglutarate (α-KG) in MPN patients. Inhibition of PI3K/AKT/mTOR signaling significantly reduced metabolic responses and hyperreactivity in MPN patient platelets, while α-KG supplementation markedly reduced oxygen consumption and ATP generation. Ex vivo incubation of platelets from both MPN patients and Jak2 V617F-knockin mice with α-KG supplementation significantly reduced platelet activation responses. Oral α-KG supplementation of Jak2 V617F mice decreased splenomegaly and reduced hematocrit, monocyte, and platelet counts. Finally, α-KG treatment significantly decreased proinflammatory cytokine secretion from MPN CD14+ monocytes. Our results reveal a previously unrecognized metabolic disorder in conjunction with aberrant PI3K/AKT/mTOR signaling that contributes to platelet hyperreactivity in MPN patients
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