简析数据加密技术在计算机网络安全中的应用

随着我国科学技术的不断发展,计算机被广泛应用于各行各业的发展建设以及人们日常生活和学习中,在给人们带来较大便利的同时,也存在安全隐患。网络安全问题威胁到了计算机信息的保密性,给计算机的可持续发展带来了安全隐患,若用户的信息被泄露会给用户带来巨大的财产损失及心理伤害。因此,出现了数据加密技术,其为计算机网络安全提供了很好的保障。基于此,论文对数据加密技术在提高网络安全性中的应用方面作了简要阐述。     

Subsidies under uncertainty: Modeling of input- and output-oriented policies

Agricultural subsidies play an essential role in agricultural and rural development in many developed economies. Countries have implemented agricultural subsidy policies with a focus on food security and environmental protection. Agricultural production is risky and uncertain, influencing the efficiency of agricultural subsidies. This study develops a theoretical framework to analyze the effects of production uncertainties on the efficiency of agricultural subsidy policies under the double constraints of food security and environmental protection. The basic model is investigated under six different conditions, and expanded research also is presented. Our models show that uncertainty, including output, cost, and price uncertainties, and technology conversion efficiency significantly affects the efficiency of agricultural subsidies. Under high technology conversion efficiency, output-oriented subsidies are appropriate for food security and environmental protection goals. Policymakers should take both uncertainty and production efficiency into consideration when choosing between input-oriented and output-oriented subsidy policies.     

A worldwide analysis of trend in crop yields and yield variability: Evidence from FAO data

The trend in crop yields and yield variability affects food security and impact agricultural and food policies. Recent studies in this area have either focused only on one country or performed global analysis on a handful of crops. We provide the first worldwide analysis of trend and variability for 8088 country-crop yield series taken from the FAO database, employing a robust estimator to cope with the adverse statistical effects of outliers. More than half of the series display a slowdown in yield growth due to a closing of the gap between realised and attainable yields as well as to agricultural policies promoting more sustainable agricultural practices. Around one fourth of the series show also an increase in yield variability as a consequence of climate change and changes in farm management practices. Yield variability is highest in Eastern Europe, Central Asia and Middle East and North Africa, where food security may be threatened.     

The long-run reversal in the long run: Insights from two centuries of international equity returns

We perform the most comprehensive test of long-term reversal in national equity indices ever done. Having examined data from 71 countries for the years 1830 through 2019, we demonstrate a strong reversal pattern: the past long-term return negatively predicts future performance. The phenomenon is not subsumed by other established cross-sectional return patterns, including the value effect. The long-term reversal is robust to many considerations but highly unstable through time. Finally, our findings support the overreaction explanation of this anomaly.     

Gender,entrepreneurship and food security in Niger

In many African countries, the income generated from the informal sector and the entrepreneurship is particularly important for reducing poverty. Previous studies have not found clear evidence on the relationship between self‐employment by gender and food security. We argue that this may be a result of the gender inequality in resource accessibility. In this paper, we analyze the implication of household entrepreneurship on food security in Niger, where gender disparities in resource accessibility are reduced. We find that owning female‐managed non‐agricultural enterprises is positively related to food accessibility and food availability within female‐headed households. The results draw the attention on reducing gender differences in resource accessibility in entrepreneurship for improving food security.     

The COVID-19 pandemic and organisational commitment of senior hotel managers

The COVID-19 pandemic will reduce the attractiveness of hospitality occupations. This particularly concerns senior management positions whose holders may substitute hospitality jobs with more secure and rewarding employment in other economic sectors. Organisational resilience of hospitality businesses, including their response to COVID-19, and corporate social responsibility (CSR) practices may, however, affect perceived job security of senior managers and, thus, influence their commitment to remain in their host organisations. This paper quantitatively tests the inter-linkages between the above variables on a sample of senior managers in hotels in Spain. It finds that the levels of organisational resilience and the extent of CSR practices reinforce perceived job security of managers which, in turn, determines their organisational commitment. Organisational response to COVID-19 affects perceived job security and enhances managers’ organisational commitment. To retain senior management teams in light of future disastrous events, hotels should, therefore, strengthen their organisational resilience and invest in CSR.     

畜牧产业结构变动对我国粮食安全的影响分析

［目的］改革开放40多年来，我国畜牧产业结构不断调整和优化，其生产供给结构与消费需求结构的变动与我国粮食安全问题息息相关。［方法］文章基于改革开放40多年来畜牧产业发展历程，从供给与需求两个维度分析我国畜牧产业结构变动的特征，并进一步探究畜牧产业结构变动与我国粮食安全间的作用机理，最后运用灰色关联度分析法实证其关联影响度。［结果］我国畜牧产业结构由耗粮型为主向节粮型转变，畜产品供给结构趋于合理，但不同区域间存在较大差异； 我国居民对畜产品消费需求量增加，但城乡居民畜产品消费结构及变动存在一定差异性； 畜牧产业结构变动与粮食安全有重要联系，畜牧业发展同保障国家粮食安全并不矛盾，畜牧产业结构变动主要通过耕地、基于口粮替代的食物需求结构变化及饲料粮需求3个方面作用于粮食安全； 具体来看，粮食播种面积、耗粮型畜产品比重和耗粮型畜产品饲料转化率对粮食安全水平的关联影响较大，节粮型畜产品比重与节粮型畜产品饲料转化率对粮食安全水平的关联影响小于耗粮型畜产品的影响。［结论］不断提高不同畜产品的饲料转化率，加大非粮型饲料资源开发利用度，推广非粮饲料应用技术，加快畜牧产业转型升级，满足消费者需求和保障国家粮食安全。     

松嫩平原自然宜垦性及耕地后备资源开发潜力

［目的］为保障我国粮食安全，为耕地后备资源的合理开发利用提供科学依据，同时完善中国区域耕地后备资源自然开发潜力方面的研究。［方法］文章从自然适宜性的角度出发，选取了地形、气候、土地类型和土壤4个方面15个评价因子，采用层次分析、专家打分等方法确定评价因子权重，构建松嫩平原宜垦性评价指标体系。［结果］（1）1980—2015年松嫩平原自然宜垦性整体较好，最适宜垦区与较适宜垦区占松嫩平原面积的5068%，分布在松嫩平原腹地大部地区，中部、中北部、中南部等地；(2)松嫩平原已开垦耕地资源中，持续利用耕地占松嫩平原面积的4814%，空间上与宜垦程度高值区高度吻合；(3)新增耕地占区域面积的126%，以中度适宜垦区和较适宜垦区为主；(4)松嫩平原耕地后备资源占松嫩平原土地面积的1556%，在松嫩平原西部地区、中部和东北部地区均有分布，耕地后备资源中度及以上宜垦区占后备资源总量的7465%。［结论］目前大庆市和白城市可开发耕地后备资源最为丰富，但其中轻度及不适宜开垦区所占比例大，开发难度较大； 松原市可开发资源相对丰富且开垦难度小。     

新中国70年中国农村社会保障制度的演进逻辑与未来展望

新中国成立以来,得益于我国综合国力的快速提升和中国特色社会主义的制度优势,我国农村社会保障事业取得了巨大成就,但仍存在社会保障制度城乡不均衡发展等重要问题。本文依据多源流模型和公共产品理论构建了我国农村社会保障制度演进的分析框架进行分析表明,我国农村社会保障制度演进大概经历了制度萌芽与停滞、恢复与探索、改革与发展、完善和提高四个阶段,人民日益增长的美好生活需要、党和国家"以人民为中心"的发展理念、政策试点与政策研究、经济体制改革与综合国力提升共同构成了农村社会保障制度演进的动力机制。针对农村社会保障制度演进面临的重要挑战,提出了加强农村社会保障治理体系现代化建设等未来展望。     

国家安全视角下的生物资源安全与保护制度研究

2014年习近平总书记提出了“总体国家安全观”理念,这是我国社会主义理论制度的又一伟大创新。本文从本次新冠疫情对于国家综合安全利益的影响出发,结合疫情对国家安全要素的扩张以及对国家安全利益的威胁等实际情况,探寻本次疫情暴露出的国家安全制度中存在的问题,以期完善我国以生物资源和公共卫生安全为代表的公共安全管理制度和疫情防控制度。