Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
12,167
result(s) for
"Li, Heng"
Sort by:
Diplomacy of quasi-alliances in the Middle East
Quasi-alliance refers to the ideation, mechanism and behavior of policy-makers to carry out security cooperation through informal political and security arrangements. As a \"gray zone\" between alliance and neutrality, quasi-alliance is a hidden national security statecraft. Based on declassified archives and secondary sources, this book probes the theory and practice of quasi-alliances in the Middle East. Four cases are chosen to test the hypotheses of quasi-alliance, one of which is the Anglo-French-Israeli quasi-alliance during the Suez Canal War of 1956.
Book
Ultra‐High Performance Amorphous Ga2O3 Photodetector Arrays for Solar‐Blind Imaging
The growing demand for scalable solar‐blind image sensors with remarkable photosensitive properties has stimulated the research on more advanced solar‐blind photodetector (SBPD) arrays. In this work, the authors demonstrate ultrahigh‐performance metal‐semiconductor‐metal (MSM) SBPDs based on amorphous (a‐) Ga2O3 via a post‐annealing process. The post‐annealed MSM a‐Ga2O3 SBPDs exhibit superhigh sensitivity of 733 A/W and high response speed of 18 ms, giving a high gain‐bandwidth product over 104 at 5 V. The SBPDs also show ultrahigh photo‐to‐dark current ratio of 3.9 × 107. Additionally, the PDs demonstrate super‐high specific detectivity of 3.9 × 1016 Jones owing to the extremely low noise down to 3.5 fW Hz−1/2, suggesting high signal‐to‐noise ratio. Underlying mechanism for such superior photoelectric properties is revealed by Kelvin probe force microscopy and first principles calculation. Furthermore, for the first time, a large‐scale, high‐uniformity 32 × 32 image sensor array based on the post‐annealed a‐Ga2O3 SBPDs is fabricated. Clear image of target object with high contrast can be obtained thanks to the high sensitivity and uniformity of the array. These results demonstrate the feasibility and practicality of the Ga2O3 PDs for applications in solar‐blind imaging, environmental monitoring, artificial intelligence and machine vision. Ultraviolet imaging technology is widely used in meteorology, medical science, and military science. For the first time, a high‐uniformity 32 × 32 solar‐blind image sensor array with outstanding imaging capability is demonstrated based on high‐performance Ga2O3 photodetectors. Schottky barrier lowering effect is experimentally revealed to attribute to the internal gain mechanism.
Journal Article
Invalidity of, and alternative to, the linear quadratic model as a predictive model for postirradiation cell survival
The linear quadratic (LQ) model has been the dominant tool in preclinical radiobiological modeling of cell survival as a function of dose. However, as a second‐order polynomial approximation, it suffers from two well‐known pitfalls: nonmonotonic behavior and poor extrapolation. This study examined the raw data of 253 sets of photons and 943 sets of the ion beam from the Particle Irradiation Data Ensemble (PIDE) project to understand how often the LQ model could result in a negative β, which would give unrealistic predictions. Additionally, the predictive performance of the LQ model, the power model, and the linear model's predictive performance was studied using leave‐one‐out cross‐validation (LOOCV) and twofold cross‐validation. It was found that, when fitted to the LQ model, 7.5% of the photon and 29.8% of the ion beam dose–response data would result in negative β, compared to 0.77% and 2.0%, respectively, reported in published works. The LQ model performed poorly in LOOCV compared to the alternative power model, and performed the worst among the three models in twofold cross‐validation. The LQ model leads to unrealistic parameters, which are vastly under‐reported in published studies, and performs poorly in standard cross‐validation tests. Therefore, the LQ model is not a valid predictive dose–response model for cell survival. Alternative models need to be investigated. This study establishes that LQ model is not a valid predicative dose‐response model for cell survival and alternative models need to be investigated. It was found 7.5% of photon and 29.8% ion beam raw cell survival data would result in negative β values when fitted to the LQ model, and as such, LQ and linear models could not provide adequate predictive results for higher dose.
Journal Article
Factorizations of Almost Simple Groups with a Solvable Factor, and Cayley Graphs of Solvable Groups
A characterization is given for the factorizations of almost simple groups with a solvable factor. It turns out that there are only
several infinite families of these nontrivial factorizations, and an almost simple group with such a factorization cannot have socle
exceptional Lie type or orthogonal of minus type. The characterization is then applied to study
eBook
Evolutionary history of Coleoptera revealed by extensive sampling of genes and species
Beetles (Coleoptera) are the most diverse and species-rich group of insects, and a robust, time-calibrated phylogeny is fundamental to understanding macroevolutionary processes that underlie their diversity. Here we infer the phylogeny and divergence times of all major lineages of Coleoptera by analyzing 95 protein-coding genes in 373 beetle species, including ~67% of the currently recognized families. The subordinal relationships are strongly supported as Polyphaga (Adephaga (Archostemata, Myxophaga)). The series and superfamilies of Polyphaga are mostly monophyletic. The species-poor Nosodendridae is robustly recovered in a novel position sister to Staphyliniformia, Bostrichiformia, and Cucujiformia. Our divergence time analyses suggest that the crown group of extant beetles occurred ~297 million years ago (Mya) and that ~64% of families originated in the Cretaceous. Most of the herbivorous families experienced a significant increase in diversification rate during the Cretaceous, thus suggesting that the rise of angiosperms in the Cretaceous may have been an ‘evolutionary impetus’ driving the hyperdiversity of herbivorous beetles.
The phylogeny of beetles, which represent ~25% of known extant animal species, has been a challenge to resolve. Here, Zhang et al. infer a time-calibrated phylogeny for Coleoptera based on 95 protein-coding genes in 373 species and suggest an association between the hyperdiversification of beetles and the rise of angiosperms.
Journal Article
Biological effectiveness and relative biological effectiveness of ion beams for in‐vitro cell irradiation
Biological effectiveness and relative biological effectiveness are critical for proton and ion beam radiotherapy. However, the relationship between the two quantities and physical character of ion beams is not well established. By analyzing 1188 sets of in‐vitro cell irradiation experiments using ion beams ranging from protons to 238U, compiled by the Particle Irradiation Data Ensemble (PIDE) project, the biological effectiveness of the ion beams, with cell survival fractionation (SF) as the endpoint, was found to be dependent on the fluence and linear energy transfer (LET) of the ion beam. Consequently, the relative biological effectiveness of the ion beam to photon beam was also established as a function of LET. A common form of relationship among SF, fluence, and LET was found to be valid for all ion beam experiments. The close form relationship could be used for proton and ion beam radiotherapy applications. This study for the first time established the relationship between post irradiation cell survival and physical character of an ion beam. The relationship is readily applicable and critical for proton and ion beam radiotherapy.
Journal Article
The design and construction of reference pangenome graphs with minigraph
The recent advances in sequencing technologies enable the assembly of individual genomes to the quality of the reference genome. How to integrate multiple genomes from the same species and make the integrated representation accessible to biologists remains an open challenge. Here, we propose a graph-based data model and associated formats to represent multiple genomes while preserving the coordinate of the linear reference genome. We implement our ideas in the minigraph toolkit and demonstrate that we can efficiently construct a pangenome graph and compactly encode tens of thousands of structural variants missing from the current reference genome.
Journal Article
Inference of human population history from individual whole-genome sequences
Human population in the genes
The history of human population size is important to understanding human evolution. Heng Li and Richard Durbin use complete genome sequences from Chinese, Korean, European and Yoruban (West African) individuals to estimate population sizes between 10,000 and 1 million years ago. They infer that European and Chinese populations had very similar size histories until about 10,000–20,000 years ago. The European, Chinese and African populations all had an elevated effective population between 60,000 and 250,000 years ago. Genomic analysis suggests that the differentiation of genetically modern humans may have started as early as 100,000–120,000 years ago.
The history of human population size is important for understanding human evolution. Various studies
1
,
2
,
3
,
4
,
5
have found evidence for a founder event (bottleneck) in East Asian and European populations, associated with the human dispersal out-of-Africa event around 60 thousand years (kyr) ago. However, these studies have had to assume simplified demographic models with few parameters, and they do not provide a precise date for the start and stop times of the bottleneck. Here, with fewer assumptions on population size changes, we present a more detailed history of human population sizes between approximately ten thousand and a million years ago, using the pairwise sequentially Markovian coalescent model applied to the complete diploid genome sequences of a Chinese male (YH)
6
, a Korean male (SJK)
7
, three European individuals (J. C. Venter
8
, NA12891 and NA12878 (ref.
9
)) and two Yoruba males (NA18507 (ref.
10
) and NA19239). We infer that European and Chinese populations had very similar population-size histories before 10–20 kyr ago. Both populations experienced a severe bottleneck 10–60 kyr ago, whereas African populations experienced a milder bottleneck from which they recovered earlier. All three populations have an elevated effective population size between 60 and 250 kyr ago, possibly due to population substructure
11
. We also infer that the differentiation of genetically modern humans may have started as early as 100–120 kyr ago
12
, but considerable genetic exchanges may still have occurred until 20–40 kyr ago.
Journal Article
Pan-cancer single-cell analysis reveals the heterogeneity and plasticity of cancer-associated fibroblasts in the tumor microenvironment
Cancer-associated fibroblasts (CAFs) are the predominant components of the tumor microenvironment (TME) and influence cancer hallmarks, but without systematic investigation on their ubiquitous characteristics across different cancer types. Here, we perform pan-cancer analysis on 226 samples across 10 solid cancer types to profile the TME at single-cell resolution, illustrating the commonalities/plasticity of heterogenous CAFs. Activation trajectory of the major CAF types is divided into three states, exhibiting distinct interactions with other cell components, and relating to prognosis of immunotherapy. Moreover, minor CAF components represent the alternative origin from other TME components (e.g., endothelia and macrophages). Particularly, the ubiquitous presentation of endothelial-to-mesenchymal transition CAF, which may interact with proximal SPP
1
+
tumor-associated macrophages, is implicated in endothelial-to-mesenchymal transition and survival stratifications. Our study comprehensively profiles the shared characteristics and dynamics of CAFs, and highlight their heterogeneity and plasticity across different cancer types. Browser of integrated pan-cancer single-cell information is available at
https://gist-fgl.github.io/sc-caf-atlas/
.
Cancer-associated fibroblasts (CAFs) are a predominant and critical component of the tumour microenvironment. Here, the authors integrate and analyse single-cell RNA-seq data of CAFs across 10 common solid cancer types, identifying their plasticity and interactions with other cell types.
Journal Article
A Periciliary Brush Promotes the Lung Health by Separating the Mucus Layer from Airway Epithelia
Mucus clearance is the primary defense mechanism that protects airways from inhaled infectious and toxic agents. In the current gel-on-liquid mucus clearance model, a mucus gel is propelled on top of a \"watery\" periciliary layer surrounding the cilia. However, this model fails to explain the formation of a distinct mucus layer in health or why mucus clearance fails in disease. We propose a gel-on-brush model in which the periciliary layer is occupied by membrane-spanning mucins and mucopolysaccharides densely tethered to the airway surface. This brush prevents mucus penetration into the periciliary space and causes mucus to form a distinct layer. The relative osmotic moduli of the mucus and periciliary brush layers explain both the stability of mucus clearance in health and its failure in airway disease.
Journal Article