Comparison Between Flat and Round Peaches, Genomic Evidences of Heterozygosity Events

Bud sports occur in many plant species, including fruit trees. Although they are correlated with genetic variance in somatic cells, the mechanisms responsible for bud sports are mostly unknown. In this study, a peach bud sport whose fruit shape was transformed to round from flat was identified by next generation sequencing (NGS), and we provide evidence that a long loss of heterozygosity (LOH) event may be responsible for this alteration in fruit shape. Moreover, compared to the reference genome, we identified 237,476 high quality single nucleotide polymorphisms (SNPs) in the wild-type and bud sport genomes. Using this SNP set, a long LOH event was identified at the distal end of scaffold Pp06 of the bud sport genome. Haplotypes from 155 additional peach accessions were phased, suggesting that the homozygous distal end of scaffold Pp06 of the bud sport was likely derived from only one haplotype of the wild-type flat peach. A genome-wide association study (GWAS) of 127 peach accessions was conducted to associate a SNP found at 26,924,482 bp of scaffold Pp06 to differences in fruit shape. All accessions with round-shaped fruit were found to have an A/A genotype, while those with A/T, or T/T genotypes had flat-shaped fruits. Finally, we also found that 236 peach accessions and 141 Prunus species with round-type fruit were found to have an A/A genotype at this SNP, while 22 flat peach accessions had an A/T genotype. Taken together, our results suggest that genes flanking this A/T polymorphism, and haplotyped carrying the T allele may determine flat fruit shape in this population. Furthermore, the LOH event resulting in the loss of the haplotype carrying the T allele may therefore be responsible for fruit shape alteration in wild-type flat peach

The Welfare Implication of Lifting the No Surcharge Rule in Credit Card Markets

This dissertation investigates the welfare implications of banning the no surcharge rule (NSR) in credit card markets. Nowadays, Visa and MasterCard have been facing antitrust and regulatory investigations all over the world. They are charged for certain business practices that may adversely affect competition. Among all the business practices, the NSR has been particularly at issue. The NSR is a business practice that prohibits merchants from charging a higher price to purchases made using credit cards than to purchases made using other forms of payment. Chapter One investigates the welfare implication of banning the NSR using a model in which a monopoly credit card company provides credit card services to both consumers and Hotelling merchants through competitive issuing banks and competitive acquiring banks. The main finding is that banning the NSR decreases social welfare, which stands in contrast with previous core literature-- namely, Rochet and Tirole (2002) (RT2002). Moreover, this unambiguous conclusion for welfare holds in a open payment system, regardless of the degree of competition among issuing banks. Chapter Two investigates the welfare implication of banning the NSR using a model in which a monopoly credit card company provides credit card services to both consumers and monopoly merchants through competitive issuing banks and competitive acquiring banks. The main finding is that banning the NSR decreases social welfare because banning the NSR results in a double marginalization problem in providing credit card services. Another contribution of this chapter is that it provides an explanation of the surcharging behavior of merchants in Australia. Chapter Three applies a model of platform competition to investigate the welfare implication of lifting the NSR in credit card markets. This paper finds that lifting the NSR always drives down the provision of credit card service below the level of a typical equilibrium in a Cournot game and always decreases social welfare. Social welfare decreases because banning the NSR opens the door for the merchant to abuse its market power in reselling the credit card service. Therefore, a new distortion is generated after the ban of the NSR, and social welfare decreases

Early Warning of Systemic Financial Risk of Local Government Implicit Debt Based on BP Neural Network Model

In recent years, local governments have boosted their local economies by raising large amounts of debt. Even though the state further strictly controls local government debt, the hidden debt formed by the local government borrowing in disguised form can infect systemic financial risks, creating an urgent need to carry out risk warning based on local government hidden debt. The paper uses the macro indicators of local government implicit debt risk at the prefecture-level city level, and introduces the micro indicators of PPP projects, financing platform bank debt, and urban investment debt to establish a BP neural network model. We not only study the contagion effect of local government hidden debt on systemic financial risks, but also predict the systemic financial risks in 2019 and construct an early warning risk system based on the prefecture-level city data from 2015 to 2018. In addition, the early warning effect of local government implicit debt on systemic financial risk under different stress scenarios is investigated. The study found that the implicit debt risk of local governments, the scale of financing platform bank debt, the scale of PPP, and the scale of urban investment bonds have a significant impact on systemic financial risks. The neural network model constructed by introducing these four variables at the same time can better predict the level of systemic financial risk. The model can also accurately predict the changes in systemic financial risks under the stress test of the increase in hidden debt of different local governments, and has a good early warning effect

Early Warning of Systemic Financial Risk of Local Government Implicit Debt Based on BP Neural Network Model

In recent years, local governments have boosted their local economies by raising large amounts of debt. Even though the state further strictly controls local government debt, the hidden debt formed by the local government borrowing in disguised form can infect systemic financial risks, creating an urgent need to carry out risk warning based on local government hidden debt. The paper uses the macro indicators of local government implicit debt risk at the prefecture-level city level, and introduces the micro indicators of PPP projects, financing platform bank debt, and urban investment debt to establish a BP neural network model. We not only study the contagion effect of local government hidden debt on systemic financial risks, but also predict the systemic financial risks in 2019 and construct an early warning risk system based on the prefecture-level city data from 2015 to 2018. In addition, the early warning effect of local government implicit debt on systemic financial risk under different stress scenarios is investigated. The study found that the implicit debt risk of local governments, the scale of financing platform bank debt, the scale of PPP, and the scale of urban investment bonds have a significant impact on systemic financial risks. The neural network model constructed by introducing these four variables at the same time can better predict the level of systemic financial risk. The model can also accurately predict the changes in systemic financial risks under the stress test of the increase in hidden debt of different local governments, and has a good early warning effect

Study on Single-Tree Segmentation of Chinese Fir Plantations Using Coupled Local Maximum and Height-Weighted Improved K-Means Algorithm

Chinese fir (Cunninghamia lanceolata) is a major timber species in China, and obtaining and monitoring the parameters of Chinese fir plantations is of great practical significance. With the help of the K-means algorithm and UAV-LiDAR data, the efficiency of forestry surveys can be greatly improved. Considering that the traditional K-means algorithm is susceptible to the influence of initial cluster centers and outliers during the process of individual tree segmentation, it may result in incorrect segmentation. Therefore, this study proposes an improved K-means algorithm that uses the methods of local maxima and height weighting to optimize and improve the algorithm. The research results are as follows: (1) Compared to the traditional K-means algorithm, the producer accuracy and user accuracy of this research algorithm have imsproved by 10.72% and 11.46%, respectively, with significant differences (p < 0.05). (2) The research algorithm proposed in this study can adapt to Chinese fir plantations of different age groups, with average producer accuracy and user accuracy reaching 78.48% and 83.72%, respectively. In summary, this algorithm can be effectively applied to the forest parameter estimation of Chinese fir plantations and is of great significance for sustainable forest management

Aperture scalable liquid crystal optically duplicated array of phased array

To achieve non-mechanical laser beam steering in the scenario of long distance propagation such as free-space laser communication between satellites, large aperture size is an inevitable issue to be considered to narrow the divergence angle of the output beam. Liquid crystal optical phased array, to be one of the solutions of non-mechanical beam steering, has already shown its obvious potential to achieve a relative large aperture on the order of centimeter. To achieve even larger, its driving matrix becomes squared larger. In this paper, we proposed a novel architecture to realize an optical phased array with a scalable aperture. Meanwhile the driving matrix is almost not increased. It provides the feature of a cascade system with a device of spatial phased modulation and an array of duplicating units. Each unit of the duplicating array is consist of a polarization beam splitter and a half wave plate to have the same output optical field distribution as the input beam whose phase front is modulated by a small size spatial modulator. Not only the property of beam deflection is numerically simulated and experimentally verified, but also the property of divergence angle compression and grating lobes limitation are evaluated. Meanwhile, due to the high precision of the experimental alignment, the non-mechanical beam deflection property is still maintained no matter how many the duplicated unit number is. The relative standard derivation steering error is 0.025

Novel use of GaAs as a passive Q-switch as well as an output coupler for diode-pumped infrared solid-state lasers

ABSTRACT Q-switched operation is very common and important for diode-pumped solid-state lasers. In this paper, we reported a novel use of GaAs wafers as Q-switch elements as well as output couplers for DPSS lasers. A pulse duration of 2.6 ns at the wavelength of 1064 nm was obtained from a diode-pumped and passively Q-switched Nd:YVO 4 laser using a piece of GaAs wafer as the saturable absorber as well as the output coupler. The transmissivity and the absorption coefficient of different wafers were studied. The experimentally measured results indicated that the transmssivity of different GaAs wafers varied from as low as ~32 % to as high as ~75 %. It was found that some of those wafers showed Fabry-Perot effect and it could affect the effective transmissvity and produce lower transmission, and thus shorten the pulse duration and stabilize the laser operation

Dynamic nucleolar phase separation influenced by non-canonical function of LIN28A instructs pluripotent stem cell fate decisions

Abstract LIN28A is important in somatic reprogramming and pluripotency regulation. Although previous studies addressed that LIN28A can repress let-7 microRNA maturation in the cytoplasm, few focused on its role within the nucleus. Here, we show that the nucleolus-localized LIN28A protein undergoes liquid-liquid phase separation (LLPS) in mouse embryonic stem cells (mESCs) and in vitro. The RNA binding domains (RBD) and intrinsically disordered regions (IDR) of LIN28A contribute to LIN28A and the other nucleolar proteins’ phase-separated condensate establishment. S120A, S200A and R192G mutations in the IDR result in subcellular mislocalization of LIN28A and abnormal nucleolar phase separation. Moreover, we find that the naive-to-primed pluripotency state conversion and the reprogramming are associated with dynamic nucleolar remodeling, which depends on LIN28A’s phase separation capacity, because the LIN28A IDR point mutations abolish its role in regulating nucleolus and in these cell fate decision processes, and an exogenous IDR rescues it. These findings shed light on the nucleolar function in pluripotent stem cell states and on a non-canonical RNA-independent role of LIN28A in phase separation and cell fate decisions