The late Pleistocene dispersal of modern humans in the Americas

When did humans colonize the Americas? From where did they come and what routes did they take? These questions have gripped scientists for decades, but until recently answers have proven difficult to find. Current genetic evidence implies dispersal from a single Siberian population toward the Bering Land Bridge no earlier than about 30,000 years ago (and possibly after 22,000 years ago), then migration from Beringia to the Americas sometime after 16,500 years ago. The archaeological records of Siberia and Beringia generally support these findings, as do archaeological sites in North and South America dating to as early as 15,000 years ago. If this is the time of colonization, geological data from western Canada suggest that humans dispersed along the recently deglaciated Pacific coastline.     

Genetic and fossil evidence for the origin of modern humans

The origin of living Homo sapiens has once again been the subject of much debate. Genetic data on present human population relationships and data from the Pleistocene fossil hominid record are used to compare two contrasting models for the origin of modern humans. Both genetics and paleontology support a recent African origin for modern humans rather than a long period of multiregional evolution accompanied by gene flow.     

Ages for the Middle Stone Age of southern Africa: implications for human behavior and dispersal

The expansion of modern human populations in Africa 80,000 to 60,000 years ago and their initial exodus out of Africa have been tentatively linked to two phases of technological and behavioral innovation within the Middle Stone Age of southern Africa-the Still Bay and Howieson's Poort industries-that are associated with early evidence for symbols and personal ornaments. Establishing the correct sequence of events, however, has been hampered by inadequate chronologies. We report ages for nine sites from varied climatic and ecological zones across southern Africa that show that both industries were short-lived (5000 years or less), separated by about 7000 years, and coeval with genetic estimates of population expansion and exit times. Comparison with climatic records shows that these bursts of innovative behavior cannot be explained by environmental factors alone.     

Lead contamination around secondary smelters: estimation of dispersal and accumulation by humans

A high rate of lead fallout around two secondary lead smelters originated mainly from episodal large-particulate emissions from low-level fugitive sources rather than from stack fumes. The lead content of dustfall, and consequently of soil, vegetation, and outdoor dust, decreased exponentially with distance from the two smelters. Between 13 and 30 percent of the children living in the contaminated areas had absorbed excessive amounts of lead (more than 40 micrograms per 100 milliliters of blood and more than 100 micrograms per gram of hair) as compared with less than 1 percent in a control group. A relationship between blood and hair was established which indicated that the absorption was fairly constant for most children examined. It seemned that the ingestion of contaminated dirt and dusts rather than "paint pica" was the major route of lead intake. Metabolic changes were found in most of 21 children selected from those with excessive lead absorption; 10 to 15 percent of this group showed subtle neurological dysfunctions and minor psychomotor abnormalities.     

Pelagic fishing at 42,000 years before the present and the maritime skills of modern humans

By 50,000 years ago, it is clear that modern humans were capable of long-distance sea travel as they colonized Australia. However, evidence for advanced maritime skills, and for fishing in particular, is rare before the terminal Pleistocene/early Holocene. Here we report remains of a variety of pelagic and other fish species dating to 42,000 years before the present from Jerimalai shelter in East Timor, as well as the earliest definite evidence for fishhook manufacture in the world. Capturing pelagic fish such as tuna requires high levels of planning and complex maritime technology. The evidence implies that the inhabitants were fishing in the deep sea.     

中国古代农业技术对现代农业发展的启示

中国古代农业技术是我国农业的关键组成部分,不仅是我国现代农业的源头所在,也是未来农业发展的重要参考。通过对汉代以来多部经典农书进行梳理,分析传统农业到现代农业发展的农业技术演进,阐明古代农业技术中的思想理念,探讨其对当代农业发展的启示意识。结果表明,我国农业大致可分为原始农业、传统农业和现代农业三个阶段。自汉代以来,从农田水利到畜禽养殖,在技术的发明和使用过程中,传统农业特别重视农业生产与自然要素相匹配,通过农业内循环方式促进农业再生产,同时也注重精耕细作与农技改良的统一。总体而言,当前绿色农业、循环农业、集约农业等现代农业发展理念与中国古代农业技术蕴含的农业实践智慧一脉相承,这些典籍为当前农业发展提供了理论指导和技术参考。古代农业技术中蕴含着生态平衡、绿色循环、实用主义等多重理念均启示现代农业应在尊重传统农业自然属性的基础上,综合考量其社会属性和工业属性,规避现代农业发展的种种风险,进而推动农业的可持续发展。     

关中东部早春茬番茄优良品种筛选

针对关中东部地区设施番茄栽培品种多、乱、杂等问题,收集国内外番茄品种24份,以‘金棚11号'作为对照,在设施条件下进行早春种植,通过对植株物候期、生长势、单果质量、产量、商品率及果实品质指标进行测定,并运用"综合满意度"比较法将各指标量化串联后综合比较。筛选出适合渭南地区早春茬种植的番茄品种。结果表明:适合渭南地区早春茬种植的番茄品种有‘瑞丽'‘金棚95-2'‘西润T1280'‘奥尼尔'‘金山511'。其综合满意度高于其他品种,主要表现为果实成熟较早,生长势强,产量及商品果率高,粉红果、中果型、果实品质优良,满足本地的生产要求和消费需求,适宜在渭南推广栽培。     

A nearly modern amphibious bird from the Early Cretaceous of northwestern China

Three-dimensional specimens of the volant fossil bird Gansus yumenensis from the Early Cretaceous Xiagou Formation of northwestern China demonstrate that this taxon possesses advanced anatomical features previously known only in Late Cretaceous and Cenozoic ornithuran birds. Phylogenetic analysis recovers Gansus within the Ornithurae, making it the oldest known member of the clade. The Xiagou Formation preserves the oldest known ornithuromorph-dominated avian assemblage. The anatomy of Gansus, like that of other non-neornithean (nonmodern) ornithuran birds, indicates specialization for an amphibious life-style, supporting the hypothesis that modern birds originated in aquatic or littoral niches.     

东部凹陷JZS地区沙三上亚段沉积相研究

首先介绍了测井相的原理,然后利用测井曲线特征对东部凹陷JZS地区沙三上亚段沉积相进行了研究,并在此基础上进行了单井相和联井相分析,最终结合地层参数(地层厚度、砂岩百分比含量等),绘制出平面相,搞清了不同沉积相的分布范围,指出了有利砂体,对储层预测和油气田的勘探开发具有重要的指导意义。     

African origin of modern humans in East Asia: a tale of 12,000 Y chromosomes

To test the hypotheses of modern human origin in East Asia, we sampled 12,127 male individuals from 163 populations and typed for three Y chromosome biallelic markers (YAP, M89, and M130). All the individuals carried a mutation at one of the three sites. These three mutations (YAP+, M89T, and M130T) coalesce to another mutation (M168T), which originated in Africa about 35,000 to 89,000 years ago. Therefore, the data do not support even a minimal in situ hominid contribution in the origin of anatomically modern humans in East Asia.     

豫东平原农业智能化气象灾害预警与防御系统研究

豫东平原农业智能化气象灾害预警与防御系统在实现了农业智能化的同时,根据豫东地区地理、气候和农业生产现状,在农业自动化灌排系统的基础上整合了农业气象监测服务系统、天气预报预警灾害防御系统,该系统可以根据气象预报预警信息自动、及时做出农事生产建议,能够自动根据土壤墒情、农作物生长状况进行灌溉、排水等。在不同地区,可以根据需要选用不同类型和功能的气象自动站,因地制宜,方便地进行农业、林业、园艺及灌溉等气象要素的监测,实现耕地园田化、灌排系统化、管理科学化、运行良性化、信息网络化、服务社会化,达到经济、社会、生态三大效益的统一。     

The land reform in independent Estonia: Memory as precedent — Toward the reconstruction of agriculture in Eastern Europe

As literally every East European nation struggles to reformits agricultural sector, land reform in its many forms figures preeminently in strategic thinking on the problem. Estonia's historic program, instituted during the first republican period, was a highly successful reform from many perspectives. With political as well as economic goals, the reform had an important social dimension as well in that it reinvigorated entire rural regions and established a vital family farming system. The land reform's achievements owe as much to the social and human infrastructure created in Estonia as it did to changes in land tenure, land assembly, and land use. This may be one of its most important lessons for those attempting to craft a new agricultural structure for this and other nations in the region.     

汉江上游东汉时期洪涝灾害及其对社会经济的影响

依据大量的历史文献资料,分析了汉江上游东汉时期洪涝灾害对社会经济的影响,探讨了该时期洪涝灾害的成因,研究结果对正确认识汉江上游历史洪涝灾害的发生规律提供了参考,对汉江流域乃至长江流域中游地区现代防洪减灾和水资源合理利用具有重要的参考价值。     

汉江上游东汉时期洪涝灾害及其对社会经济的影响

依据大量的历史文献资料,分析了汉江上游东汉时期洪涝灾害对社会经济的影响,探讨了该时期洪涝灾害的成因,研究结果对正确认识汉江上游历史洪涝灾害的发生规律提供了参考,对汉江流域乃至长江流域中游地区现代防洪减灾和水资源合理利用具有重要的参考价值。     

Disturbance and the dispersal of fleshy fruits

Fruits of Prunus serotina, Phytolacca americana, and Vitis vulpina were placed during separate trials in forest sites that varied in the degree to which the forest canopy was disturbed. Removal rates of fruits were consistently faster in the forest edge and light gap sites than in sites under closed canopy. Rapid removal of fruits from species that ripen fruit in summer and early fall is selectively advantageous to the plants because it minimizes the probability that fruits will be destroyed by invertebrates before dispersal. Disturbances probably play an important role in interactions between temperate fruits and birds and in community organization.     

The southern route "out of Africa": evidence for an early expansion of modern humans into Arabia

The timing of the dispersal of anatomically modern humans (AMH) out of Africa is a fundamental question in human evolutionary studies. Existing data suggest a rapid coastal exodus via the Indian Ocean rim around 60,000 years ago. We present evidence from Jebel Faya, United Arab Emirates, demonstrating human presence in eastern Arabia during the last interglacial. The tool kit found at Jebel Faya has affinities to the late Middle Stone Age in northeast Africa, indicating that technological innovation was not necessary to facilitate migration into Arabia. Instead, we propose that low eustatic sea level and increased rainfall during the transition between marine isotope stages 6 and 5 allowed humans to populate Arabia. This evidence implies that AMH may have been present in South Asia before the Toba eruption.