The Impacts of Collective Action in Common-Pool Resources ——Evidence From the Field of Grassland Use

The deterioration of common-pool resources is a serious issue faced by over the world now. How to manage public resources sustainably is extremely urgent. Collective action plays an important role in the sustainable management of common-pool resources. It creates a common goal that makes resource users not only concern their individual interests, but also the collective interests, in order to avoid the common-pool resource dilemma. The extent of collective interests that resource users concern affects their decisions in collective action, which further impacts the sustainable use of common-pool resources. We use a grazing experiment to observe and measure collective action. Combining the experimental data with the data in the real world, we find that resource users with more collective interests in collective action have higher grassland quality and less grazing livestock. Moreover, we use principal components analysis measuring collective action indicators to verify the robustness of these findings. A mechanism analysis is conducted to explain why collective action has positive effects on grassland restoration. Heterogeneity analysis examines the different impacts of collective actions with various natural endowments and individual characteristics. This study proves that collective action has positive impacts on the sustainable management of common-pool resources, which provides an empirical evidence on sustainable use of public natural resources through community-based natural resource management

Re-ViLM: Retrieval-Augmented Visual Language Model for Zero and Few-Shot Image Captioning

Augmenting pretrained language models (LMs) with a vision encoder (e.g., Flamingo) has obtained the state-of-the-art results in image-to-text generation. However, these models store all the knowledge within their parameters, thus often requiring enormous model parameters to model the abundant visual concepts and very rich textual descriptions. Additionally, they are inefficient in incorporating new data, requiring a computational-expensive fine-tuning process. In this work, we introduce a Retrieval-augmented Visual Language Model, Re-ViLM, built upon the Flamingo, that supports retrieving the relevant knowledge from the external database for zero and in-context few-shot image-to-text generations. By storing certain knowledge explicitly in the external database, our approach reduces the number of model parameters and can easily accommodate new data during evaluation by simply updating the database. We also construct an interleaved image and text data that facilitates in-context few-shot learning capabilities. We demonstrate that Re-ViLM significantly boosts performance for image-to-text generation tasks, especially for zero-shot and few-shot generation in out-of-domain settings with 4 times less parameters compared with baseline methods.Comment: Findings of EMNLP 202

The Association Between Diabetic Retinopathy and the Prevalence of Age-Related Macular Degeneration—The Kailuan Eye Study

This study aimed to investigate the prevalence of age-related macular degeneration (AMD) in patients with diabetes mellitus (DM) and diabetic retinopathy (DR) and analyze whether DR is a risk factor for AMD. This population-based epidemiological study included 14,440 people from the Kailuan Eye Study in 2016, of whom 1,618 were patients with type 2 DM aged over 50 years, and 409 had DM with DR. We analyzed whether there were differences in the prevalence of AMD between DM with DR and DM without DR, and conducted a hierarchical statistical analysis according to different stages of DR. Using variable regression analysis, we explored whether DR constituted a risk factor for AMD. In the DM population, the prevalence of wet AMD in patients with DM with and without DR was 0. 3 and 0.2%, respectively, with no significant difference (P = 0.607). Meanwhile, the prevalence of dry AMD in patients with DM with and without DR was 20.8 and 16.0%, respectively, with a significant difference. In the subgroup analysis of dry AMD, the prevalence of early, middle, and late dry AMD in DM with DR was 14.4, 5.9, and 0.5%, respectively. In DM without DR, the prevalence of early, middle, and late dry AMD was 10.5, 4.8, and 0.7%, respectively (P = 0.031). In the subgroup analysis of DR staging, statistical analysis could not be performed because of the limited number of patients with PDR. In the variable regression analysis of risk factors for dry AMD, after adjusting for age, sex, body mass index, hypertension, and dyslipidemia, DR constituted the risk factor for dry AMD. In conclusion, DM did not constitute a risk factor for AMD, and the prevalence of wet AMD and dry AMD in patients with DM and DR was higher than that in patients with DM without DR (among which dry AMD was statistically significant). Multivariate regression analysis confirmed that DR is an independent risk factor for dry AMD. Reasonable control of DM and slowing down the occurrence and development of DR may effectively reduce the prevalence of AMD in patients with DM

Constructing the Spectrum for Maximum Packings of Complete Graphs with Stars of Size Six

A 6-star is the complete bipartite graph $K_{1,6}$. A \emph{packing of $K_{n}$ with 6-stars} is a set of edge disjoint subgraphs of $K_{n}$, each of which is isomorphic to $S_{6}$. The set of edges of $K_{n}$ which are not used in the packing is called the leave and is denoted by $L$. The packing is called \emph{maximum} if $|L|$ is minimum with respect to all such packings. We show that every possible leave graph is achievable as the leave of a maximum packing of $K_{n}$ with 6-stars

Cooperation, institutions and sustainable development: empirical evidence from China

Cooperation is vital for the sustainable development of human society. For the sustainable long-term development of human society, cooperation is essential in solving social dilemma situations ranging from local issues such as the management of local common pool resources to global issues such as climate changes. Understanding what affects cooperation and how to improve cooperation is crucial in this respect. This thesis examines factors that affect cooperation among individuals in the context of China. It starts with an assessment of an eco-certification program for agricultural products, where cooperation among a larger number of farmers is crucial for its success. Upon finding that free-riding incentives are behind the ineffectiveness of the eco-certification system in reducing agrochemical use, this thesis proceeds to explore how various contextual and institutional factors affect cooperation. First, it looks at the role of contextual factors, specifically, the role of resource scarcity in shaping cooperation in the context of irrigation agriculture. Then, it moves on to the role of punishment and reward institutions in improving cooperation with particular attention to people’s institutional preferences. And last, this thesis examines the effect of leading-by-example and leadership legitimacy on promoting cooperation. In Chapter 2, we examine the effectiveness of food certification in reducing agrochemical consumption in China. Specially, we use panel data from 4,830 different households in six provinces coving the period of 2005-2013 to test whether the adoption of certified food production reduces the use of chemical fertilizers and pesticide in China. On average, we do not find evidence support the hypothesis that adopting certified food production reduces farmers’ agrochemical consumption. The effects are heterogeneous across villages, but the heterogeneous effects show no clear pattern that is consistent with the requirement of different types of certification. We find evidence suggesting that lack of knowledge about certification among farmers, weak inspection and the monetary incentives (price premium for certified products) for farmers to defect may explain why eco-certifications largely fails to reduce agrochemical use. We interpret the role of monetary incentives in explaining the ineffectiveness of food certification in terms of a lack of cooperation among farmers. In Chapter 3, we study the impact of long-term exposure to resource scarcity on cooperation among farmers using data from a household survey and a lab-in-the-field experiment with 312 male subjects in rural northwestern China. The unique historically formed irrigation water quota system allows us to measure exogenous variation in scarcity level of available water resource within an otherwise homogenous region. We find that water scarcity improves irrigation management in term of both the irrigation-related activities and their outcomes: people living in more water scarce villages are more likely to coordinate in crop choices, more likely to keep local canals clean and higher self-reported quality of canals. More important, we find that the impact of water scarcity goes beyond irrigation-related activities. People in villages with higher level of water scarcity also make significantly higher contributions in the public goods game. This result suggests that water scarcity strengthens norms of cooperation within rural communities. In Chapter 4, we investigate how the people’s institutional preferences interact with assigned institutions in the context of public goods games and what factors are behind people’s institutional preferences using a lab-in-field experiment with 312 male subjects in rural northwestern China. We find that subjects have stronger preference for the reward institution over the punishment institution. But whether subjects’ preferred institution matches the exogenously assigned institution or not does not have significant impacts on their contributions in the public goods game. Moreover, we find that subjects who prefer punishment tend to be free-riders. This finding makes the preference for the punishment puzzling and intriguing. Neither strategic concerns nor game history can fully explain why some people prefer punishment and the negative relationship between the preference for punishment and contributions in PGGs. We further find that the there is a robust relationship between the preference for the punishment institution and certain “efficiency-reducing” or “anti-social” social preferences profiles. In Chapter 5, we look at the role of leadership and leadership legitimacy in promoting cooperation using a lab experiment with 272 college students in China. We use a special experimental design to select leaders from the procedure and manipulate leadership legitimacy perception though manipulating the information provided to the leaders. We find that having a leader improves cooperation in the public goods game. The increase of group contributions is induced by the leader’s contributions. Being a leader in makes leaders increase their contributions, and followers reciprocate but to a slightly smaller extent and thus they harvest the gains from increased group contributions. The perception of leadership legitimacy does not have additional impacts on the leaders’ contribution level and the group contribution level. But we find evidence suggesting that leadership legitimacy influences how leaders make their contributions decisions and update their beliefs in the repeated public goods game. It seems that only “legitimate” leaders show the strategic use of “leading-by-example”, not “appointed” leaders, whose higher contributions as leaders are simply a reaction to the sequential move game structure where their behavior can be observed by others. While each chapter is a stand-alone research article answering a specific research question, they all revolve around the common topic of voluntary cooperation. The existence of free-riding incentives and the lack of cooperation hamper the effort of achieving sustainable development. We set out to explore different ways to overcome free-riding incentives and achieve better cooperation among individuals. Directly or directly, these chapters also all feature the role of institutions. Proper institutions can either directly influence people’s cooperative behavior or set the ground for other factors.</p

Recursive Sequences and Girard-Waring Identities with Applications

This poster is about generalized Girard-Waring identity constructed from recursive sequences. We also present the construction of Binet Girard-Waring identity and classical Girard-Waring identity by using the generalized Girard-Waring identity and divided differences. Also include the applications of the generalized Girard-Waring identity to the transformation of recursive sequences of numbers and polynomials is discussed

Constructing all Possible Leaves for Maximum Packings of the Complete Graph with Stars of Sizes Six and Seven

A 6-star is the complete bipartite graph K1,6. A packing of Kn with 6-stars is a set of edge disjoint subgraphs of Kn, each of which is isomorphic to S6. The set of edges of Kn which are not used in the packing is called the leave and is denoted by L. The packing is called maximum if |L| is minimum with respect to all such packings. We show that every possible leave graph is achievable as the leave of a maximum packing of Kn with 6-stars and 7-stars

Girard-Waring Identities and Their Applications

Our research project is about application of recursive sequences in the construction of a class of combinatorial identities called Girard-Waring identities. This type of identities is derived from recursive sequences, which is the motivation and the guiding light of our path to deeper understanding of mathematics. A sequence constructed from a recessive relation is called recursive sequence, which starts from a few initial quantities to generate a sequence of quantities by using a simple relationship in modeling some real world problems or mathematical problems. As a natural math model of those problems, recursive sequences are an important tool widely used in Combinatorics and Graph Theory, Number Theory, Fractal, Cryptography, etc. Many identities in elementary mathematics and other advanced mathematics come from the Girard-Waring identities. We connected the generating function of a linear recursive sequence and its explicit expression to give an efficient method to construct Girard-Waring type identities. We also used the method in the study of some construction problems such as summation formulas, Hagen-Rothe type identities, etc. In addition, some applications of those summation formulas and identities are discussed

Resource scarcity and cooperation : Evidence from a gravity irrigation system in China

Resource scarcity has become an increasingly pressing challenge to the world. How scarcity affects people's preferences and behavior has been taken as an important issue for development. This study examines the impact of long-term exposure to resource scarcity on farmers’ cooperation. Specifically, we focus on water scarcity in irrigation agriculture, and examine the effect of water scarcity on cooperation in the context of a gravity irrigation system in western China. A historical irrigation water quota system provides an opportunity to measure exogenous variations of water scarcity within an otherwise homogeneous region. We use the ratio of the arable land area to the irrigation water quota of each village as our measure of water scarcity. Moreover, we use the contributions in a public goods game to measure the farmers’ willingness to cooperate. Combining a household survey and a lab-in-the-field experiment with 312 rural residents in northwestern China, we find that irrigation water scarcity significantly increases farmers’ willingness to cooperate. The results are robust to potential endogeneity concerns and many confounding factors. We also find that water scarcity is positively correlated with irrigation management activities and canal conditions. Our findings provide important policy implications for common pool resource management and collective actions in rural communities.</p

Vulnerability assessment and analysis of cryosphere changes in the Western Sichuan Plateau

ABSTRACTA vulnerability assessment model and indicator system for the changes in the cryosphere in the Western Sichuan Plateau are constructed based on the “exposure–sensitivity–adaptive capacity” framework. The model aims to capture the multiple characteristics of vulnerability to cryosphere changes in the region by selecting influencing factors from three dimensions: exposure, sensitivity, and adaptive capacity. Furthermore, the study explores the interrelationships among vulnerability dimensions and employs geographical detectors to analyze the driving mechanisms of vulnerability. The ultimate goal is to provide a scientific and rational basis for developing effective adaptation strategies to prevent and mitigate cryosphere-related disasters in the area. The main findings are as follows: (1) The vulnerability to cryosphere changes in the Western Sichuan Plateau exhibits a distribution pattern characterized by higher vulnerability in the west and lower vulnerability in the east. (2) There is a significant correlation between vulnerability and geographical location, characterized by two types of distribution patterns: high–high aggregation and low–low aggregation. The aggregation patterns are relatively stable but exhibit spatial heterogeneity. (3) The vulnerability to cryosphere changes in the Western Sichuan Plateau is the combined result of natural geographical conditions, socioeconomic development levels, and other factors