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The trajectory and influencing factors for changes to ancient human livelihoods in the Hexi Corridor of northwest China have been intensively discussed. The Hexi Corridor is a key crossroads for trans-Eurasian exchange in both the prehistoric and historical periods. Although most studies have focused on the reconstruction of human paleodiet and plant subsistence, the diachronic change of animal utilization strategies spanning the prehistoric and historical periods remains unclear, due to the absence of zooarchaeological and isotopic studies, especially in Han Dynasty (202 BCE–220 CE). Here we report new zooarchaeological, stable isotope, and radiocarbon dating data from the Heishuiguo Cemetery of the Han Dynasty in the Hexi Corridor, indicating that humans mainly used domestic chickens, pigs and sheep as funerary objects, with other buried livestock including cattle, horses and dogs. Stable carbon and nitrogen isotope data suggest humans might have fed chickens, pigs and dogs more C4 foods (likely millets or their byproducts) than herbivorous livestock in the Heishuiguo during the Han Dynasty. Compared to other prehistoric zooarchaeological and isotopic studies in the Hexi Corridor, we detected an increasing significance of herbivorous livestock in animal utilization strategies compared with omnivorous livestock, and a basic declining weight of C4 foods in fodders from ∼2,300 to 200 BCE, which was probably induced by long-distance exchange and climate fluctuation. However, the trend was reversed during the Han Dynasty in the Hexi Corridor, primarily due to the control of the area by the Han Empire and the subsequent massive immigration from the Yellow River valley of north China.

The history of forager subsistence strategies on the Tibetan plateau during the middle Holocene has been studied extensively, with valuable results from archaeozoology and archaeobotany being produced in recent years. However, changes to the resources collected by the foragers and the factors that influence them have rarely been discussed. Here we examine the differences and factors influencing charcoal identification and analysis results from both hand picking and flotation recovery methods at the Zongri site, revealing more accurately the use of firewood by the foragers and its relationship with climate change and the agricultural population. Our results show that there is a clear deficiency in tree taxa arising from hand picking, perhaps related to the quantity of charcoal collected and identified. The Zongri people mainly used nearby trees and shrubs, including Picea (spruce), Populus (poplar) and Hippophae (sea buckthorn). The material collected was dominated by green (living) wood, which might have been influenced by the farming culture in the adjacent area. The increasing use of Picea may be attributed to the selective collection of wood by the Zongri foragers, and not caused by climate change.

Background Nitrogen is considered the most limiting nutrient element for herbivorous insects. To alleviate nitrogen limitation, insects have evolved various symbiotically mediated strategies that enable them to colonize nitrogen-poor habitats or exploit nitrogen-poor diets. In frugivorous tephritid larvae developing in fruit pulp under nitrogen stress, it remains largely unknown how nitrogen is obtained and larval development is completed. Results In this study, we used metagenomics and metatranscriptomics sequencing technologies as well as in vitro verification tests to uncover the mechanism underlying the nitrogen exploitation in the larvae of Bactrocera dorsalis. Our results showed that nitrogenous waste recycling (NWR) could be successfully driven by symbiotic bacteria, including Enterobacterales, Lactobacillales, Orbales, Pseudomonadales, Flavobacteriales, and Bacteroidales. In this process, urea hydrolysis in the larval gut was mainly mediated by Morganella morganii and Klebsiella oxytoca. In addition, core bacteria mediated essential amino acid (arginine excluded) biosynthesis by ammonium assimilation and transamination. Conclusions Symbiotic bacteria contribute to nitrogen transformation in the larvae of B. dorsalis in fruit pulp. Our findings suggest that the pattern of NWR is more likely to be applied by B. dorsalis, and M. morganii, K. oxytoca, and other urease-positive strains play vital roles in hydrolysing nitrogenous waste and providing metabolizable nitrogen for B. dorsalis.

The relationship between archeological culture and ethnicity is invariably complex. This is especially the case for periods of national division and rapid inter-ethnic exchange, such as China’s Sixteen Kingdoms (304–439 CE) and Northern and Southern Dynasties (420–589 CE). Going by tomb shape and grave goods, the Foyemiaowan cemetery at Dunhuang exhibits a typical third–tenth century Han style. Despite this, the ethnic makeup of the Foyemiaowan population has remained unclear. We therefore analyzed 485 Y-chromosomal SNPs and entire mitochondrial genomes of 34 Foyemiaowan samples. Our study yielded the following discoveries: (1) principal component analysis revealed that the Foyemiaowan population was closely clustered with Tibeto-Burman populations on the paternal side and close to Mongolic-speaking populations on the maternal side; (2) lineage comparisons at the individual level showed that the Foyemiaowan population consisted of primarily Tibeto-Burman and Han Chinese related lineages (Oα-M117, 25%;Oβ-F46, 18.75%), partially Altaic speaking North Eurasian lineages (N-F1206, 18.75%) and a slight admixture of southern East Asian lineages (O1b1a2-Page59, 6.25%; O1b1a1-PK4, 3.13%). Similarly, the maternal gene pool of Foyemiaowan contained northern East Asian (A, 4.17%; CZ, 16.67%; D, 20.83%; G, 4.17%; M9, 4.17%), southern East Asian (B, 12.51%; F, 20.83%) and western Eurasian (H, 4.17%; J, 4.17%) related lineages; (3) we discovered a relatively high genetic diversity among the Foyemiaowan population (0.891) in our ancient reference populations, indicating a complex history of population admixture. Archeological findings, stable isotope analysis and historical documents further corroborated our results. Although in this period China’s central government had relinquished control of the Hexi Corridor and regional non-Han regimes became the dominant regional power, Foyemiaowan’s inhabitants remained strongly influenced by Han culture.

The Tuyuhun Kingdom (AD 313–663) was one of the most famous regimes in northwest China during the early medieval period. However, the lifestyle and spiritual pursuit of their descendants who became allied with the Tang Dynasty remain enigmatic. The excavation of the Chashancun cemetery, a Tuyuhun royal descendant (AD 691) cemetery in the Qilian Mountains in northwest China, reveals a large amount of uncharred plant remains. These remains provided a rare opportunity to explore the geographical origin of the buried crops and their social implications. In total, 253,647 crops and 12,071 weeds were identified. Foxtail millet and broomcorn millet represent 61.99 and 30.83% of the total plant remains, with the rest being barley, buckwheat, beans, and hemp. The oxygen isotope and trace elements of the crop and weed remains suggest that broomcorn millet, foxtail millet, barley, buckwheat, and hemp were sourced from different regions. The assemblage of plant remains in the Chashancun cemetery suggests that millet cultivation played an important role in the livelihoods of Tuyuhun descendants, and the location of the elite Tuyuhun cemetery and multisources of different buried crops may reflect their memory of ancestors and homelands. This case study provides a unique perspective to understand the interactions among human subsistence strategy, geopolitical patterns, and local natural environments in northwest China during the late 7th century.

Animal husbandry has been an indispensable part of human subsistence since the origin of agriculture. Along with the prehistoric cultural exchange, several kinds of major domestic animals diffused and gradually got popularized across the Eurasia. The specific geographic setting makes the Hexi Corridor in northwestern China one of the key regions to converge various types of major crops and livestock, and to witness the deep impact of novel species on local subsistence. Archeological evidence reveals an emergence of early oriental-occidental cultural communication at the opening of the local Bronze Age in Hexi Corridor, resulting in a significant shift of local subsistence. However, due to the lack of more detailed archeological evidence, the initial timing and trajectory of the transformation of livestock feeding patterns remain unclear. In this study, we reported systematic stable isotope and precise radiocarbon dating analyses on faunal remains unearthed from Huoshiliang and Ganggangwa, two Early Bronze Age settlements (ca. 4,000–3,700 BP) in middle Hexi Corridor. Our results show distinct diversification in livestock feeding patterns at ∼3,850 cal BP; in contrast with previous periods, some omnivorous livestock appear to have consumed mainly C3 foodstuff and some herbivorous livestock primarily consumed C4 plants. Combined with published stable isotope data and other archeological findings in the neighboring region, a clearer trajectory of the evolution of livestock feeding patterns has been revealed with diversified strategy amid the transformation during the Early Bronze Age in Hexi Corridor. We argued that the alteration of the local livestock feeding pattern reflects the attempt to achieve more efficient economy and sustainable society, in order to withstand the harsh arid environment in Hexi Corridor.

Archaeological research has documented the migration of Neolithic farmers onto the Tibetan Plateau by 4000 BC. How these incoming groups interacted, if at all, with local indigenous foragers, however, remains unclear. New archaeobotanical and zooarchaeological data from the Zongri site in the north-eastern Tibetan Plateau suggest that local foragers continued to hunt but supplemented their diet with agricultural products in the form of millet. The authors propose that, rather than being grown locally, this millet was acquired via exchange with farmers. This article highlights how indigenous foragers engaged in complex patterns of material and cultural exchange through encounters with newly arrived farmers.

The reconstruction of high-resolution chronologies for prehistoric cultures is a prerequisite for understanding the history of human evolution and its relationship with environmental change, and is valuable for exploring the trajectory of transcontinental cultural exchanges in prehistoric time. The Hexi Corridor of northwest China was one of the earliest centers for long-distance culture exchange in the prehistoric world. The timing and sequence of cultural changes in this area remains poorly understood resulting from the lack of radiometric age control. This paper presents a refined radiocarbon (14C) chronology to resolve the timing of human occupation and cultural evolution in the Hexi Corridor. Radiocarbon dating of crop remains, which have an annual life cycle, has the advantage of eliminating problems such as the carbon stored in ‘old wood’. As a result, 14C dates from crop remains are used to test the validity of the 14C dates derived from charcoal, bone and plant remains. The resultant database of ages is modelled using the Bayesian approach. The updated chronology presented in this paper shows generally good agreement with the original dates used to constrain cultural evolution in the Hexi Corridor. However, the occupation of the corridor by the Shajing and Shanma Late Bronze Age-Early Iron Age cultures appears to have taken place ~300 years later than previously thought. On the basis of comparing this updated chronology of cultural evolution with palaeoclimatic and historical records, it is proposed that the collapse of the Shajing and Shanma cultures occurred as a result of geopolitical impact rather than climate change.

The development and subsistence strategies adopted in ancient settlements are crucial to the understanding of long-term human–environmental interaction in the past. Here, we reassess the chronology of the ancient walled settlement of Sanjiao in the Hexi Corridor in northwestern China through accelerator mass spectrometry radiocarbon (AMS14C) dating and explore the subsistence of the settlers inside through the identification of carbonized seeds and charcoal. In addition, high-resolution paleoclimate records in the Hexi Corridor and nearby regions are employed to explore the reason for the construction of Sanjiao. Our results show that Sanjiao was built around 828 cal BC and remained inhabited through 384–116 cal BC. This indicates Sanjiao is the earliest known walled settlement in the Hexi Corridor. Ancient people at Sanjiao consumed crops such as barley, broomcorn millet, and foxtail millet, and used wood fromTamarix chinensis,Tamarix,Salix,Picea,Hippophae,Betulaceae, andPoaceaeas fuel. The construction date of Sanjiao correlates with climate deterioration and social upheavals in the Hexi Corridor, potentially suggesting a defensive purpose for the site.

In recent years, archaeologists have studied how ancient humans have shaped, and been shaped by, their surrounding environments in an effort to provide valuable insight into the patterns of human-environment interaction during prehistoric and historical periods. Along the Heihe River in Hexi Corridor of northwest China, archaeologists have found many ancient cities that are good places to explore changes in human settlement patterns in relation to environment change in historical periods. In this paper, we present our investigation of seven ancient cities to clarify the chronology of these cities and their strategy for wood use in the area through the application of radiocarbon dating and charcoal identification. Our results suggest that the ages of many cities are younger than previous estimates, and humans mainly used Tamarix and mixed Tamarix and broad leaf trees in the lower and middle reaches of the Heihe River basin between ∼ AD 240–1380 respectively, and roughly matches the modern spatial distribution of natural woody vegetation in the area. In comparison to the results of archaeological, paleoclimatic and historical studies in Hexi Corridor, we propose that ancient human strategies for wood use and their impact on environment of the Heihe Basin are primarily relevant to human lifestyles rather than climate change.

BackgroundCA242 is a classic biomarker used for diagnosing digestive tract tumors, especially pancreatic cancer. However, CA242 serum levels in some tumor patients and what might influence these levels remain unknown or uncertain. This study aimed to reveal the pancancer landscape of serum CA242 levels and identify some influencing factors.MethodsIn the current study, serum CA242 levels and clinical information, including clinical stage and metastatic status, were collected from 37,493 patients with 35 different types of neoplastic disease, and CA242 values were also obtained for 880 healthy controls.ResultsSerum CA242 levels in patients with one of 21 different cancers were significantly higher than those in healthy controls and had diagnostic value in 9 tumors (AUC>0.7, PConclusionsOverall, CA242 can not only serve as a diagnostic biomarker for malignant tumors in the digestive system but also predict the progression, stage, and metastasis of many other tumors that have not received clinical attention.

Stable isotopic analyses of the remains of plants that have been unearthed from archaeological sites are often featured as key indicators of crop cultivation and the living environment. However, systematic archaeobotanical studies have not been applied widely in Chinese historical sites, especially in those from the Tang dynasty. This paper aims to use carbon and nitrogen isotopic analyses to reveal the potential influence of water and fertilizer conditions on the size of millet chaffs that were excavated from the Chashancun cemetery. To achieve this, >3600 uncharred broomcorn and foxtail millet chaff remains were measured. Furthermore, 30 broomcorn millet samples and 30 foxtail millet samples were selected to analyze the carbon and nitrogen isotopes, respectively. The widths and thicknesses of the broomcorn millet chaffs ranged from 1.11 to 2.38 mm and from 0.95 to 2.24 mm, respectively, while those of the foxtail millet chaffs ranged from 0.95 to 1.94 mm and from 0.69 to 1.90 mm, respectively. The δ13C and δ15N values of the broomcorn millet chaffs ranged from −13.0‰ to −12.0‰ and from 15.7‰ to 17.8‰, respectively, while those of the foxtail millet chaffs ranged from −14.0‰ to −12.9‰ and from 15.7‰ to 18.8‰, respectively. The results show correlations between the millet chaff size and the carbon/nitrogen isotopic values, suggesting that water and fertilizer conditions might have significantly affected millet grain yield during the late seventh century in northwestern China.

Automated analog circuit design is promising for increasing the design productivity and narrowing the time-to-market, but is facing the bottleneck of tremendous design complexity. In this paper, a simulation-based optimization approach named smart-multiple starting point (MSP) is proposed for analog circuit synthesis. The proposed smart-MSP is based on the framework of MSP optimization, which is shown to be much more efficient than other global optimization methods like simulated annealing, genetic algorithm, particle swarm optimization, etc. Efficient techniques including heuristic-biased starting point selection, sparse regression and probabilistic TABU are developed in smart-MSP and make the algorithm quite smart in a way that the overall optimization process is self-adaptive by learning from the previous local searches and can efficiently produce optimal results to approximate the global optimum. Experiments have demonstrated that the proposed smart-MSP is ${2.6-12.5\times }$ faster than the original MSP method, and is $ {1.3-2100\times }$ faster than other state-of-the-art methods.

We report dozens of direct radiocarbon dates on charred grains from 22 archaeological sites of the Neolithic and Bronze Ages in the Hexi Corridor, northwest China, a key region for trans-Eurasian exchange in prehistoric and historical times. These charred grains include remains of wheat and barley domesticated in southwest Asia and broomcorn and foxtail millet which originated from north China. Together with previously published radiocarbon dates, we consider these newly obtained radiocarbon results in the context of material cultures associated with them, to explore an episode of trans-continental cultural exchange foci at the Hexi Corridor. Our results show that millet cultivators who used painted potteries from the western Loess Plateau first settled the Hexi Corridor around 4800 BP. Communities who cultivated wheat and barley moved into this region from the west around 4000 BP, bringing with them technologies and materials not seen in central China before, including bronze metallurgy, mud bricks, and mace heads. This was part of the east-west contact which became evident in the Hexi Corridor since the late fifth millennium BP, and continued over the subsequent two millennia, and predated the formation of the overland Silk Road in the Han Dynasty (202 BC-AD 220).

The emergence and diffusion of metallurgical technology had tremendous environmental consequence, however, the spatial-temporal consequences of the metallurgy during Bronze Age are not clear in China. In this paper, X-ray fluorescence (XRF) measurement and principal component analysis (PCA) were conducted on heavy metal element (Cu, Ni, Pb, Zn, Cr and As) concentrations (HMEC) of natural and anthropogenic sediment samples systematically collected from 22 late Neolithic-Bronze Age sites in Hexi corridor to explore the potential for subcontinental-wide changes in soil geochemistry. We place this data within the context of the Cu concentrations in lacustrine sediments located near smelting and mining centers in Bronze Age China. Our results show that variation of HMEC in anthropogenic sediment in Hexi corridor is contemporaneous with the increases of the Cu concentrations in lacustrine sediment around 4000 BP. Comparative data suggests the metallurgical production diffused from the Hexi corridor to central and southwestern China around 3600 BP. We argue that sediment pollution is not an isolated phenomenon during the Bronze Age China, but rather occurred on regional scales and is closely related to the intensity of smelting activities.

All around the world, ancient legends exist about the Great Flood, and the influence of the Great Flood in human evolutionary history is a hotly debated topic. In China, the legend of the prehistoric Great Flood and Yu the Great’s flood control has a long history and is considered to be closely linked to the establishment of the Xia Dynasty. However, there is a lack of solid scientific evidence. Against this issue, some scholars have proposed that an earthquake around 1920 BCE in the Guanting Basin along the upper reaches of the Yellow River led to the creation of a lake by damming in the Jishi Gorge and that the outburst of water from that lake led to the massive flood in the Yellow River region. These studies provided new scientific evidence for the Chinese legend. In this paper, we date skeletal samples embedded in earthquake sand blasting from the Lajia site, analyze remains from natural disasters (such as earthquakes and floods) and also archaeological remains. In addition, we compared the skeletal samples dating with that of sediments from the dammed-up lake. Our results are inconsistent with those of previous scholars. The earthquake at the Lajia site occurred no earlier than 1800 BCE, and the dammed-up lake in Jishi Gorge had disappeared by 3600 BCE. Thus, the formation and outburst of the dammed lake, the sudden death of ancient humans at the Lajia site and the ancient earthquake were independent events occurring at different times. In addition, the massive flood in the upper reaches of the Yellow River did not actually happen. Thus, we argue against and invalidate the hypothesis that the massive flood was related to Yu the Great’s flood control and the establishment of the Xia Dynasty.

The history of cultural exchange in prehistoric Eurasia (CEPE) has been widely investigated. Based on archaeological evidence, this process is thought to date back to at least the early Bronze Age, although details about timings and routes remain unclear. It is likely that CEPE promoted the spread and exchange of crops that originated in different parts of Eurasia; since these remains can be definitely identified and directly dated, they provide ideal research materials to explore the history of CEPE. In this paper, we review the available archaeobotanical evidence and direct radiocarbon dates for crop remains, alongside carbon isotopic data from human bones unearthed from prehistoric sites in Eurasia, in order to investigate the history of the spread of millet crops, and wheat and barley, that were first domesticated in the eastern and western parts of Eurasia during prehistoric times. In combination with other archaeological evidences, we discuss the history of CEPE. Our results suggest that wheat and barley were domesticated in western Asia around 10500 a BP, spread into Europe and western Central Asia before 8000 a BP, and reaching eastern Central Asia and northwestern China between 4500 and 4000 a BP. Data show that both broomcorn and foxtail millet were domesticated in eastern Asia before 7700 a BP, spread into eastern Central Asia between 4500 and 4000 a BP, and into western Asia and Europe prior to 3500 a BP. Wheat, barley, and millet crops were first utilized together in eastern Kazakhstan within Central Asia around 4400 a BP, the region where earliest CEPE is likely to have taken place. These crops were mixedly used mainly in eastern central Asia and northwest China between 4500 and 3500 a BP, and then across the Eurasia before 2200 a BP. The results of this study suggest that transcontinental CEPE might have been initiated during the fifth millennium, before intensifying during the Bronze Age to lay the foundations for the creation of the ancient Silk Road during the Han Dynasty (between 202BC and 220AD).

Gansu and Qinghai provinces of northwest China form an important region for the domestication and early utilization of millet crops. Studies on the subsistence strategy variation and environmental background of prehistoric cultural transition in this area have made substantial progress, but the geomorphic environment and hydrologic conditions of the different culture stages remains poorly known. Based on high resolution DEM and GPS coordination of typical sites, a GIS aided hydrogeomorphic analysis was conducted to indicate the abundance of cultivable flat lands and proximity to local surface runoff within walking access of nine typical sites. The results were compared with the records of plant-animal remains and tool assemblages from published literature. There is a good correlation between sites' hydrogeomorphic settings and the subsistence strategy adopted. Our case study provides valuable information for understanding how humans selected their habitat locations in corresponding to subsistence strategy shift during the transitional period between late Paleolithic and Neolithic periods.

The study of the history of human activities in ancient cities has provided valuable evidences for understanding the evolution of human-land relations during the late Holocene. Numerous ancient cities were discovered through archaeological surveys of the east Qinghai Province, located on the northeastern border of the Tibetan Plateau, China; however, the mystery of when or why these cities were built remains unsolved. As recorded in this paper, we sampled reliable dating materials from 47 ancient cities in the area, determined their ages by radiocarbon dating, and compared the dating results with historical documents and high resolution paleoclimate records to explore the influencing factors for the development of these ancient cities. The 54 radiocarbon dates indicated that most of these cities were built or repaired during the Han Dynasty (202 BC‒AD 220), Tang Dynasty (AD 618‒AD 907), the Five Dynasties and Ten Kingdoms period (AD 907‒AD 960), the Song dynasty (AD 960‒AD 1279), and the Ming Dynasty (AD 1368‒AD 1644). The radiocarbon dates correspond well with historical records of the area. Our work suggests the ancient cities in east Qinghai Province were likely built primarily for military defense, and may have also have been affected by climate change.

The nature of an Anthropocene has been increasingly discussed and debated in the last two decades, with a focus on the arguments for or against the “Anthropocene” as a geological epoch. Some argue for an onset of Anthropocene between 1945‒1964 AD, when intensive atmospheric nuclear testing resulted in peak values of 14C that is widely recorded in tree rings and sediments, while other scholars argued its beginning may be traced back to the early Holocene. This latter argument is related to the beginnings of significant landscape modification through the development and spread of agricultural practices in old world since 10000 a BP. The Yellow River valley of northern China is the center for the domestication of millet crops (broomcorn millet and foxtail millet), however, the intensification and expansion of millet-based agriculture during the Neolithic period and its impact on the environment has not been well understood. Recent development of archaeometry methods and their application to archaeological research, such as archaeobotanical studies, and carbon and nitrogen isotope analysis of human and animal bones unearthed from Neolithic and Bronze sites in north China, has greatly deepened our understanding of the timing of millet-based agriculture and its development. In parallel, the analysis of paleoenvironment proxies including black carbon and pollen assemblages from natural sediments, has shed light on the impact of human slash-and-burn cultivation on their surrounding environments during both prehistoric and historical times. This paper reviews carbon isotope analysis of human, pig and dog bones, and radiocarbon dates from Neolithic sites, and compares them with black carbon content from palaeoenvironment records in northern China, in order to explore the temporal-spatial intensification and expansion of millet-based agriculture in the area and its possible impact on environment. It can be concluded that millet cultivation was an auxiliary subsistence strategy in northern China from 10000 to 7000 a BP with hunting-gathering the primary subsistence strategy, the earliest millet-cultivation might have emerged in eastern Inner Mongolia post 7700 a BP. Millet cultivation transited from a secondary strategy to become dominant in the Guanzhong area of north-central China during 7000‒6000 a BP, and probably facilitated the development of early Yangshao culture in the middle reaches of the Yellow River valley. Intensive millet-based agriculture emerged and widely expanded across the Yellow River valley in northern China during 6000‒4000 a BP. This promoted rapid population growth and cultural evolution in the late Neolithic period, and was key in the subsequent emergence of the ancient Chinese civilization. The temporal-spatial variation of black carbon (EC-soot) corresponds well with the intensification and expansion of millet-based agriculture during Neolithic period. The content of EC-soot increased in sediments of Daihai lake and the Horqin sandy lands in Inner Mongolia from about 7500 a BP soon after farming of millet appeared in Xinglongwa and Xinglonggou sites nearby, which evidently increased in Shaanxi Province of north central China post 6000 a BP, when intensive millet-based agriculture firstly emerged in the area. This suggests millet agriculture production activities exerted significant impact on fire frequency in northern China during the Neolithic, and thus the scale and intensity of the impact of farming increased from that period. This work provides a valuable case study for understanding the temporal and spatial development of millet agriculture, and human-environment interactions in northern China during Neolithic period from an Anthropocene perspective.

Charcoal analysis is a useful tool to gather information about the diversity of vegetation as well as human behaviour towards the environment and the diversified management of natural plant resources. Here we present the taxonomic identification of charcoal and calculate the percentage of each diameter class of the pieces excavated from the Shannashuzha archaeological site, Gansu Province. We discuss the implications of the data for the composition of the past woodland vegetation and prehistoric human fuel collection strategy. Twenty-two taxa were identified from 2,241 charcoal fragments with a further 50 fragments unidentified. Picea, Pinus, Bambusoideae, Salix, Populus, Quercus and Betula were abundant in many samples, although Bambusoideae is probably over-represented due to its high chance of being preserved. The vegetation around the Shannashuzha site had a typical mountain character and the main vegetation types reflected by the charcoal records included conifer woods, mixed broadleaved/conifer woods and riverbank broadleaved woods. This vegetation is similar to the modern vegetation and therefore the climate at that time is deemed to have been similar to or slightly warmer than today. Abundance was probably an important factor in the fuel collection strategy of the people. Collection of wood with a small diameter was a purposeful choice by prehistoric people, probably because it was less time-consuming in the study area, which was rich in wood resources. We conclude that in this region, prehistoric people selected firewood depending not on its type, but rather on its size (diameter). Charcoal from fruit trees found at this site and at many others nearby indicates that there was a common and long history of fruit utilization by prehistoric people in the western Loess Plateau. These results provide valuable information and a new insight into the interaction between human activities and plant resources in the Neolithic period.

The Hexi Corridor of northwestern China was a principal axis of cultural interchange between eastern and western Eurasia during the prehistoric and historic epochs. Neolithic groups began dense settlements in Hexi Corridor after 4300 BP with millet crops and polychrome pottery from north China and bronze from Central Asia around 4000 BP accompanied by wheat, barley, and sheep. The impact of these activities on the environment during the late Neolithic and Bronze Age is not clearly understood. Therefore, we analyzed the Cu concentrations of samples collected within cultural layers of anthropogenic sediments from 17 Late Neolithic and Bronze Age sites located within the Hexi Corridor. The Cu content is reported in view of the archaeological and paleoclimatic research undertaken in the area. Our results enabled us to explore the variety of human impact on the environment before and after the introduction of bronze technology into Hexi Corridor. During 4300–4000 BP, Cu concentrations of the anthropogenic sediments were constrained within natural background values. However, from 4000 to 3400 BP, they increased substantially and far exceeded the natural background. The Cu concentrations then declined and remained above the natural background from 3000 to 2400 BP. Our work suggests that the introduction of copper melting technology led to human alteration of sediments’ chemical properties in their surrounding environments in Hexi Corridor since 4000 BP; its intensity was closely related to human settlement density, which was further affected by climate change and livelihood transition in the area during Bronze period.

Millimeter-wave radar has attracted much attention as a replacement of some infrared or laser systems currently in use. In this paper, an approach of developing high performance waveform for full-coherent millimeter-wave radar is proposed. With good frequency configuration and optimal utilization of DDS (direct digital synthesizer), PLL (phase locked loop) and FPGA (field programming gate array), the developed radar waveform generator implemented with low complexity has the good performance of both spectrum purity (phase noise and spur level) and switching speed. The measurement results show that, in S/C band, the local oscillator's bandwidth is 480MHz and the minimum frequency step is 15MHz, the spur level is better than -65dBc, the phase noise level is better than -94dBc/Hz@1kHz, the maximum frequency switching time is less than 15mus.