Small scale mining has always been part of life in Ghana, but its illegal form known as galamsey has grown into one of the country’s biggest problems. Galamsey gives work to many people, yet still it destroys rivers, forests and farms, leaving communities struggling to survive. This paper looks at the laws that guide small scale mining in Ghana, from the days of traditional mining, through the colonial period, the Small Scale Gold Mining Law of 1989, and the Minerals and Mining Act, 2006 (Act 703) as amended by Act 995. It explains how weak enforcement, corruption, political interference and the role of foreigners, especially some Chinese nationals, have made the laws less effective. The paper also shows, through recent court cases such as Republic v Fynn and Republic v Domotey and Others, that Ghana’s courts are ready to punish offenders when cases are well presented. The courts have given long prison terms and heavy fines, showing that they are not the weak link in the fight. The real problem is poor enforcement and selective justice, since many foreigners are deported instead of being put on trial. The paper argues that solving the galamsey problem needs strong enforcement, freedom from political interference, the setting up of special environmental courts, and better job opportunities for rural communities. With these steps, Ghana can protect the environment while also supporting its people to make a living in lawful ways.

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当今社会最大矛盾是国家法定数字货币供给不足，社会分工无法通过足够的数字货币进行交换，导致有产品卖不出，有需要却没钱支付的怪圈。解决这个问题可以通过给居民按身份证发放法定数字贷币，让社会分工通过数字货币交换，而不是原始的物物交换。发放数字货币不是不劳而获，因为数字货币本身不能吃不能用，要得到需要的东西就需要有付出或对等服务去交换，数字货币底层逻辑是交换的载体并不代表财富，只有满足公平交换的规则，社会才能激发创造力和分工协作，有了交易交换才能带动就业和税收，社会才能稳健有序发展。

本文基于间接融资体系抵押品本位，构建涵盖银行信贷与REITs资产的全口径抵押财富测度框架，利用跨国与城市面板数据开展实证检验。结果显示，抵押品减值对金融风险存在9.7%与24.8%两道临界门槛，跨门槛后冲击强度阶梯式抬升，且呈显著非对称特征，价格止跌不足以推动资产负债表回归稳态。纳入市场摩擦与货币稀释双重约束后，全国层面稳态修复的最低估值缺口约为10.6%-12.1%，三四线城市所需修复幅度明显更高。总量货币、财政与柔性监管三类常规工具仅在短期缓释风险，商用不动产证券化可在同等跌幅下将系统性风险降低24%-27%，但无法完全替代抵押品估值修复。本文为四部门资产负债表修复与不动产证券化制度设计提供了量化参考。

This paper investigates the weekly evolution of child skills as measured by unique data from a widely-emulated early childhood home-visiting program developed in Jamaica, adapted to rural China, and applied in different versions worldwide. The design of the study avoids problems of endogeneity of inputs and lack of truly comparable measures of skills across children that plague previous econometric studies of child development. Skills that are nominally classified as the same, in fact, do not appear to share a common unit scale across levels. They are produced by skill-specific, lifecycle-stage-specific technologies. We formulate and estimate a new dynamic stochastic skill production model for multiple skills that is consistent with the evidence. We quantify the dynamics of early life learning. The model explains the “fadeout” of measures of learning by the emergence of new skills not properly measured. We investigate the role of ability in learning. We find important differences in learning patterns between boys and girls.

城镇居民收入持续正增长，非必需消费增速却从高位大幅回落，2022年起更是逼近零增长。这一“收入稳、消费停”的矛盾格局，暴露出现行消费理论对中国居民行为的结构性盲区。本文从抵押品约束视角切入，构建“抵押品单向派生安全垫与杠杆率——双指标双向反馈——消费非对称突变”的完整因果链条。研究发现：抵押品是安全垫与杠杆率的单向底层驱动因素，反向不存在长期因果关系；双指标无固定线性相关，上行周期同向变动，下行周期反向变动，突破阈值后形成共振放大。最核心的发现是：下行阶段对非必需消费的抑制力度是上行提振的3.09倍，其中2.25倍源于损失厌恶，0.84倍来自信贷刚性收缩与宏观负螺旋。安全垫指数跌破100、居民杠杆率突破45%两条阈值击穿后，消费抑制效应非线性跳升，叠加下跌加速度、持续时长、跌幅深度、外部冲击与偿债压力五层因素，冲击强度进一步逐级放大。

Straddle Option is a financial trading tool that explores volatility premiums in high-volatility markets without predicting price direction. Although deep reinforcement learning has emerged as a powerful approach to trading automation in financial markets, existing work mostly focused on predicting price trends and making trading decisions by combining multidimensional datasets like blogs and videos, which led to high computational costs and unstable performance in high-volatility markets. To tackle this challenge, we develop automated straddle option trading based on reinforcement learning and attention mechanisms to handle unpredictability in high-volatility markets. Firstly, we leverage the attention mechanisms in Transformer DDQN through both self-attention with time series data and channel attention with multi-cycle information. Secondly, a novel reward function considering excess earnings is designed to focus on long-term profits and neglect short-term losses over a stop line. Thirdly, we identify the resistance levels to provide reference information when great uncertainty in price movements occurs with intensified battle between the buyers and sellers. Through extensive experiments on the Chinese stock, Brent crude oil, and Bitcoin markets, our attention-based Transformer-DDQN model exhibits the lowest maximum drawdown across all markets, and outperforms other models by 92.5% in terms of the average return excluding the crude oil market due to relatively low fluctuation.

基于资本“金融生息与生产增值”的二重属性，本文构建二维资本汇率定价理论（Capital-Pricing Exchange Rate Theorem,CPERT）。从无套利公理出发证明：汇率由利差与资本边际产出（MPK）差值共同决定，两大因子近似独立且定价权重对等，无摩擦环境下对冲系数精确等于√2。传统无抛补利率平价仅为该框架在MPK差值为零时的特殊形式。三维数据集（1998—2025年，中美长时序+省级面板+27国跨国面板）的实证结果验证了这一理论预言：双因子模型调整后R²为81.27%，较传统单一利差模型提升约17个百分点；24个市场化经济体的对冲系数均值为1.450，与√2理论基准的相对偏差约为2.54%，统计上无法拒绝二者相等的原假设。研究进一步识别出跨境资本的三层异质性，以及利差与MPK的双重门槛效应，据此划分四类汇率风险状态。由此形成的√2双重稳健性标准、金融结构杠杆乘数与三元悖论弹性系数三类工具，可应用于跨境收支统计校验与宏观政策评估。二维框架弱化了传统三元悖论的刚性约束，为开放经济体协同实现货币政策独立与汇率稳定提供了量化依据。

全球美元流动性的周期性涨跌被学界称作 “美元潮汐”，传统研究过度强调美联储政策、跨境资本等外生因素，不仅存在因果逻辑倒置问题，也难以精准研判周期演化趋势。本文以 1900—2025 年美国长时序数据为样本，提取十年期美债收益率的中长期周期成分作为观测变量，结合非线性框架下的临界逃逸速度与结构相变理论展开实证研究。结果显示，人口代际滞后特征与住房按揭存续周期构成了美元潮汐的内生底层约束；人口结构、住房偿债负担率、资本边际产出三类核心变量，对美元潮汐外生波动的解释力度达到 51.7%。1983 年是美元运行体系发生永久性结构突变的关键节点，适龄购房人口占比突破 22.0% 临界阈值后，市场波动模式发生本质转变，形成稳定的周期性运行态势。外部扰动仅具备短期效应，无法左右周期的中长期运行轨迹。本文厘清了美元潮汐的内生形成机理，实证发现 26 年人口代际周期与美元潮汐周 期存在固定嵌套关系，一个完整人口代际周期恰好对应 1.5 轮美元潮汐。

As companies and investors globalize, we are increasingly faced with estimation questions about the risk associated with this globalization. When investors invest in China Mobile, Infosys or Vale, they may be rewarded with higher returns, but they are also exposed to additional risk. When Siemens and Apple push for growth in Asia and Latin America, they clearly are exposed to the political and economic turmoil that often characterize these markets. In practical terms, how, if at all, should we adjust for this additional risk? We will begin the paper with an overview of overall country risk, its sources and measures. We will continue with a discussion of sovereign default risk and examine sovereign ratings and credit default swaps (CDS) as measures of that risk. We will extend that discussion to look at country risk from the perspective of equity investors, by looking at equity risk premiums for different countries and consequences for valuation. In the fourth section, we argue that a company’s exposure to country risk should not be determined by where it is incorporated and traded. By that measure, neither Coca Cola nor Nestle are exposed to country risk. Exposure to country risk should come from a company’s operations, making country risk a critical component of the valuation of almost every large multinational corporation. In the final section, we will also look at how to move across currencies in valuation and capital budgeting, and how to avoid mismatching errors.