Appreciating migration flows for health/social services planning: A case study of older adults leaving from New York to Florida

This paper utilizes the 2009/2010/2011 American Community Survey to examine spatial patterns of later-life relocation from the state of New York into Florida. Given that the first-wave of the Baby Boom generation reached the retirement age of 65 years in January 2011 and many more will continue to do so, examining the mobility/subsequent residential choices of this group is a worthwhile undertaking. This research paper is also a noteworthy contribution because it offers an interdisciplinary study of spatial statistics and population geography. Exploratory spatial analysis and multinomial regressions suggest older adults from New York leave select origins, such as Capital District, Mid-Hudson, and Lower Hudson. In addition, these older adults select preferred destinations in Florida, such as Fort Myers, Fort Pierce–Stuart, and West Palm Beach. This finding can inform planners, policy analysts, and social workers about how to best address issues related to health and community services since not all older adult migrants seeking coastal and recreational areas in Florida maintain greater wealth and better health.     

Slavery scandals: Unpacking labour challenges and policy responses within the off-shore fisheries sector

Over the past year, scandals around what has been labelled slave labour in the industrial fisheries sector in Thailand have revealed not only the connections between northern buyers and southern labour practices, but also the relative lack of research on fisheries labour in Asia and the global South. The slavery and trafficking framings pervading these depictions have been very useful for drawing attention to and acting on criminal activities in labour recruitment and abuse, but have limits as a basis for addressing the underlying causes of forced labour in fisheries. Insights from research on regional labour migration as well as the work of civil society organisations in Thailand suggest that broader improvements in labour relations will require changes in migration management, with a focus on addressing vulnerabilities that restrict the abilities of migrant workers to obtain better working conditions. This analysis provides the basis for assessing the potential and limits of recent programmes to improve labour relations on the oceans, including anti-trafficking policies, IUU enforcement, buyer efforts to ensure that supply chains do not involve forced or illegal labour relations, and Thai government actions.     

Analysis of sediment stability on the Peru‐Chile continental slope

Abstract

Potential sediment mass movement was analyzed at ten locations on the continental slope off Peru and northern Chile, using samples obtained from up to 3 m below the seafloor. Shear strength parameters were obtained from consolidated‐undrained triaxial compression tests. Sediment behavior in these tests reflects the influence of organic matter, which is concentrated in the slope deposits by coastal upwelling. High water content of the organic‐rich sediments and the high de‐formability of organic matter contribute to the prevalent ductile behavior. Aggregation of clays by organic matter is apparently responsible for the high friction angles, up to 44°, displayed by the slope deposits. Sediment stability was assessed using infinite slope analyses. These analyses indicate that gravitational forces alone are not sufficient to cause sediment failure at any of the slope locations. Sediment accumulation on the slope is not rapid enough to generate excess pore pressure and reduce the resistance to gravitational sliding. Effects of earthquakes on slope stability were evaluated by modeling earthquake‐induced inertia forces as static forces and estimating pore pressures developed during cyclic loading. This analysis shows that sediments of the lower slope off Peru possess the highest susceptibility to failure during earthquakes. Earthquake accelerations on the order of 0.2 gravity are sufficient to trigger slumping at all ten slope locations. Indirect evidence suggests that creep and mass flows initiated at shallower water depths are factors that might contribute to sediment failure on the slope.     

基于QHAdam梯度优化算法的最小二乘逆时偏移

最小二乘逆时偏移(LSRTM)通常基于梯度类算法, 经过几十次甚至上百次的迭代得到最终的成像剖面, 然而常规最小二乘逆时偏移其在迭代过程中, 所求梯度通常不做优化处理, 导致最小二乘逆时偏移的收敛效率和成像精度不高, 并且每次迭代的模型更新处理还需付出1~2次的波场延拓计算代价来获取迭代步长.本文将深度学习中的优化算法QHAdam引入到传统时间域最小二乘逆时偏移计算中, 可在付出极小计算代价的前提下, 直接获得优化的模型更新量, 同时避免了迭代步长的求取.Marmousi模型实验结果显示, 相比于常规最小二乘逆时偏移算法, 基于QHAdam梯度优化算法的最小二乘逆时偏移其收敛效率和成像精度更高, 且由于减少了迭代步长的求取步骤, 其也具有更高的计算效率; 相对于基于Adam算法最小二乘逆时偏移, 本文方法也具有更高的收敛效率和收敛精度.

     

Lateral sediment transport by bedforms in a meander bend

Bedforms and their migration are among the most important features determining bed load transport on point bars in sand-bedded rivers. A case study has been carried out in the Danish river Gels Å in a bend with equilibrium point bar topography. Bedforms (dunes) were repeatedly surveyed to determine the bedform migration on the point bar surface. Bedforms occur in two categories in the bend: primary dunes and secondary dunes migrating transversely in the troughs between primary dunes. The study shows that the migration of these bedforms can account for the entire lateral transport known to concentrate the transport in the convex half of the cross section at the bend exit. The bedform transport is induced by both dune categories, partly by turning of the primary dunes towards the convex bank and partly by the migration of secondary dunes. In certain areas, the two categories operate together and thus make the lateral transport particularly large; it is shown that almost 60 per cent of the entire lateral transport in the bend takes place within less than 30 per cent of the streamwise extent of the point bar.     

单程波角度域内压制多次波偏移假象

多次波偏移中的假象主要来自于不同地震事件之间的互相关,由于这种互相关满足成像条件,很难直接在偏移过程中去除.但是对于准确的速度模型,真实的成像结果在角度域内应该是平直的.根据这个判断准则,可以在角度域内移除多次波偏移中的假象.本文以数据自相关偏移为例,提出了在单程波多次波偏移中移除假象的主要流程：首先在在单程波偏移过程中高效地提取角度域共成像点道集,然后对角度域共成像点道集应用高分辨率的抛物线型Radon变换,用合适的切除函数处理后,反变换回到角度域,最后叠加各个角度成分,得到偏移结果.Marmousi模型的合成数据测试表明,这种方法可以很好地压制多次波偏移过程中产生的假象,有效地提高成像结果的信噪比.     

‘European Generation of Migration’: Change and agency in the post-2004 Polish graduates’ migratory experience

This paper suggests that a constant exposure to and experience of socio-historical and economic changes throughout young people’s formative years assist in development of individualisation and human agency capabilities, which impact on motivations for migration.Focusing on the cohort of Polish graduates, born in the late 1970s and early 1980s, who migrated to England post-2004, the paper highlights a relationship of individuals with change. It argues that frequent and major changes shaped such generational units into highly responsive, easily adjustable and focused on capitalising upon further relationship with change, e.g. through migration.The paper distinguishes two generational units within the researched cohort: ‘Generation of Change’ and ‘European Generation of Opportunities and Migration’. It also highlights that one of the motivations for migration of both groups is practical consciousness (Giddens, 1984) inaccessible to mindful reflection in migration motivations to England.Correspondingly, the paper contends that a generational belonging encompasses both the intentional and non-discursive agency in migratory contexts. Therefore, it is significant to explore and understand individuals’ generational vantage view of the world.     

弹性波克希霍夫积分偏移法

P、S波同时偏移法是为了适应复杂构造地区勘探情况而开始研究的一种偏移方法。在前人工作的基础上,应用弹性波克希霍夫积分偏移的基本原理,改进了纵波（PP）及转换波（PS）的同时克希霍夫积分偏移方法,给出了一种近于实用的计算机流程和程序;并用其分别对射线理论合成反射波资料、有限元模拟地震波传播资料进行了检验,证明此种方法是有效的。在解决复杂构造地区的地震波成象方面,该方法具有很大的潜力。     

油气超长运移距离

塔里木盆地塔北地区广泛分布着来自于库车坳陷的陆相油气,其运移距离超过100km,是一个比较典型的油气超长距离运移实例。本文在结合油气勘探基础资料的基础上,通过对出油井的详细地球化学研究,综合油气运移条件的分析,探讨了油气超长运移的地质条件与动力机制。研究认为,在哈拉哈塘和英买力南部地区白垩系砂岩储层中发现的油气来源于北部库车坳陷的三叠系湖相烃源岩,成藏时间在5~3Ma;油气主要通过断裂沟通不整合面以及白垩系巴西改组的砂体进行长距离侧向运移,运移的直线距离达到110~130km。研究发现,库车坳陷三叠系优质烃源岩短期内快速熟化并高效排烃,为油气长距离运移提供了充沛的油源和驱动力条件;白垩系巴西改组油层在致密顶底板岩层的封堵约束作用下,油气沿着宽缓斜坡上大面积分布的连通砂体呈面状发生长距离运移,沿途缺少大型圈闭拦截和聚油,油气损失相对较少,所以油气在通畅的运移道路上持续向南推进,这是该区油气发生超长运移的主要动力机制。超长的运移距离,与该区低幅度宽缓的斜坡构造背景和良好的输导通道密切相关,因此,在已发现白垩系出油井点以南更远地区还将不断会有陆相油的新发现;在油气运移经过的地区,白垩系内只要存在圈闭,均可形成油藏,因此,低幅度构造圈闭与岩性地层圈闭所形成的中小型油气田群将作为今后勘探的主要目标。