Metal semiconductor metal photodiodes based on all-epitaxial Ge-on-insulator-on-Si(111), grown by molecular beam epitaxy

We report on the fabrication and characterisation of an all-epitaxial Germanium-on-Insulator (GOI) Metal-Semiconductor-Metal (MSM) photodetector. The MSM photodetector is fabricated on a (111)-oriented epitaxial Ge layer, grown on an epitaxial Gd 2 O 3 /Si(111) substrate, by molecular beam epitaxy (MBE). The first step is the growth of the 15-nm thick Gd 2 O 3 epitaxial layer over CMOS-grade silicon, atop which an epitaxial layer of Ge is grown. Near infrared (NIR) MSM photodetectors have been fabricated over the Ge epitaxial layer with an inter-digitated (IDT) contact structure, with an active area of 100 μm x 124 μm. For the particular IDT dimensions, the dark current has been measured to be 475 μA. A responsivity of ∼ 2 mA/W is observed at a-5V bias, when excited at 1550 nm. © 2019 SPIE

Journey to the east: Diverse routes and variable flowering times for wheat and barley en route to prehistoric China.

Today, farmers in many regions of eastern Asia sow their barley grains in the spring and harvest them in the autumn of the same year (spring barley). However, when it was first domesticated in southwest Asia, barley was grown between the autumn and subsequent spring (winter barley), to complete their life cycles before the summer drought. The question of when the eastern barley shifted from the original winter habit to flexible growing schedules is of significance in terms of understanding its spread. This article investigates when barley cultivation dispersed from southwest Asia to regions of eastern Asia and how the eastern spring barley evolved in this context. We report 70 new radiocarbon measurements obtained directly from barley grains recovered from archaeological sites in eastern Eurasia. Our results indicate that the eastern dispersals of wheat and barley were distinct in both space and time. We infer that barley had been cultivated in a range of markedly contrasting environments by the second millennium BC. In this context, we consider the distribution of known haplotypes of a flowering-time gene in barley, Ppd-H1, and infer that the distributions of those haplotypes may reflect the early dispersal of barley. These patterns of dispersal resonate with the second and first millennia BC textual records documenting sowing and harvesting times for barley in central/eastern China

The virtues of small grain size: Potential pathways to a distinguishing feature of Asian wheats

Increase in grain/seed size recurrently features as a key element in the ‘domestication syndrome’ of plants (cf. Zohary and Hopf 2000; Fuller et al. 2014). In the context of its spread across Eurasia, however, the grain size of one of the world's major crop species underwent a substantial reduction. Between the fifth and second millennia BC, the grain length in a number of species of Triticum, collectively known as free-threshing wheat, decreased by around 30%. In order to understand and help account for this trend, we have obtained direct radiocarbon measurements from 51 charred wheat grains and measured the dimensions of several hundred grains from Asia to establish when and where that size diminution occurred. Our results indicate that the pace of a eastward/southward spread was interrupted around 1800 BC on the borders of the distinct culinary zone recognized by Fuller and Rowlands (2011), but regained pace around 200–300 years later in central-east China with a diminished grain size. We interpret this as evidence of a period of active crop selection to suit culinary needs, and consider whether it constitutes a distinct episode in the general character of genetic intervention in domesticated species.Financial support was provided by the European Research Council, under grant 249642 (FOGLIP), UKIERI – UK & India Collaborative Educational Research Initiative, and the International Center for Advanced Renewable Energy and Sustainability, Washington University in St. Louis

Barnyard grasses were processed with rice around 10000 years ago

Rice (Oryza sativa) is regarded as the only grass that was selected for cultivation and eventual domestication in the Yangtze basin of China. Although both macro-fossils and micro-fossils of rice have been recovered from the Early Neolithic site of Shangshan, dating to more than 10,000 years before present (BP), we report evidence of phytolith and starch microfossils taken from stone tools, both for grinding and cutting, and cultural layers, that indicating barnyard grass (Echinochloa spp.) was a major subsistence resource, alongside smaller quantities of acorn starches (Lithocarpus/Quercus sensu lato) and water chestnuts (Trapa). This evidence suggests that early managed wetland environments were initially harvested for multiple grain species including barnyard grasses as well as rice, and indicate that the emergence of rice as the favoured cultivated grass and ultimately the key domesticate of the Yangtze basin was a protracted process

Correction: Journey to the east: Diverse routes and variable flowering times for wheat and barley en route to prehistoric China.

[This corrects the article DOI: 10.1371/journal.pone.0187405.]

Between China and South Asia: A Middle Asian corridor of crop dispersal and agricultural innovation in the Bronze Age

© The Author(s) 2016. The period from the late third millennium BC to the start of the first millennium AD witnesses the first steps towards food globalization in which a significant number of important crops and animals, independently domesticated within China, India, Africa and West Asia, traversed Central Asia greatly increasing Eurasian agricultural diversity. This paper utilizes an archaeobotanical database (AsCAD), to explore evidence for these crop translocations along southern and northern routes of interaction between east and west. To begin, crop translocations from the Near East across India and Central Asia are examined for wheat (Triticum aestivum) and barley (Hordeum vulgare) from the eighth to the second millennia BC when they reach China. The case of pulses and flax (Linum usitatissimum) that only complete this journey in Han times (206 BC–AD 220), often never fully adopted, is also addressed. The discussion then turns to the Chinese millets, Panicum miliaceum and Setaria italica, peaches (Amygdalus persica) and apricots (Armeniaca vulgaris), tracing their movement from the fifth millennium to the second millennium BC when the Panicum miliaceum reaches Europe and Setaria italica Northern India, with peaches and apricots present in Kashmir and Swat. Finally, the translocation of japonica rice from China to India that gave rise to indica rice is considered, possibly dating to the second millennium BC. The routes these crops travelled include those to the north via the Inner Asia Mountain Corridor, across Middle Asia, where there is good evidence for wheat, barley and the Chinese millets. The case for japonica rice, apricots and peaches is less clear, and the northern route is contrasted with that through northeast India, Tibet and west China. Not all these journeys were synchronous, and this paper highlights the selective long-distance transport of crops as an alternative to demic-diffusion of farmers with a defined crop package

Dislocation density and strain-relaxation in Ge1-xSnx layers grown on Ge/Si (001) by low-temperature molecular beam epitaxy

The density and origin of dislocations in a variety of molecular-beam-epitaxy-(MBE)-grown Ge1-xSnx/Ge/Si (001) heterostructures, with Sn-content varying from 0.4 to 5.2%, have been investigated systematically by high resolution X-ray diffraction (HRXRD). In particular, using the approach due to Kaganer et al. (V.M. Kaganer et al., Phys. Rev. B 72, 045423 (2005)) for the first time to the Ge1-xSnx alloy, it is demonstrated that reliable estimates of both edge and screw dislocation densities can be obtained from HRXRD data. Based on the correlations of strain relaxation and dislocation densities of the alloy epilayers and the underlying Ge buffer layers, we observe that dislocations threading from the latter predominantly contribute to the strain relaxation of the former. Thus, Ge1-xSnx epilayers of sub-critical thicknesses can be made to relax significantly by growing them on partially-relaxed, relatively-thin Ge buffer layers. This may be promising for the realization of Ge1-xSnx epilayers with direct electronic band gap. (C) 2017 Elsevier B.V. All rights reserved

The wind that shakes the barley: the role of East Asian cuisines on barley grain size

This paper investigates the eastern movements of barley grains and their morphological variations in prehistory. By combining previously published and newly collected archaeobotanical grain measurements (n = 2,176), we explore the roles of culinary traditions underlying the morphological traits observed. We find that barley diminished in size as it moved from its origin in southwestern Asia to Central and East Asia between the third millennium BC and first millennium BC. In particular, the grains in Monsoonal China became greatly reduced in comparison to other regions as the crop was incorporated into eastern small grain cuisines. The reverse pattern is observed in the high-altitude Tibetan environment, which is attributed to the practicalities of cooking under low vapour pressure conditions. These results, demonstrating that barley moved eastward but western grinding and baking traditions did not, reveal the complexity of the eastern culinary system and raise awareness of decoupling of grains and their associated cuisines.Introduction Materials and methods - Materials - Methods Results - Regional barley measurements - Elevation - Hulled and naked barley Discussion - Grain size reduction as barley heads east - Hulled, naked, two- and multiple row varieties - Tibetan boiling-steaming free zone - Towards a complex culinary system in eastern Eurasia Conclusion

Multiproxy analysis on Indian wild ass (<em>Equus hemionus khur</em>) dung from Little Rann of Western India and its implications for the palaeoecology and archaeology of arid regions

The dung of the Indian wild ass was analyzed using biotic and abiotic proxies to determine its dietary habits inrelation to the plant diversity and ecology in the arid region of western India. The presence of both micro andmacrobotanical remains of Poaceae, Chenopodiaceae, and Fabaceae indicates they are the primary food plantsof thewild ass. The continuous recovery of arboreal pollen taxa chiefly, Prosopis, Acacia, and Ephedra is indicativeof dry thorny forest under semi-arid to arid conditions which display the existing vegetation and climate in theregion. The recovery of marshy pollen taxa like Cyperaceae and Onagraceae along with Arcella indicates utilizationof water-logged environments in the habitat. Spores of coprophilous fungi, Sporormiella, Sordaria, andPodospora are also present in the dung samples. The low value of stellate trichomes in winter dung samples reflectsthe seasonal migration of wild ass. Average δ13C values ranging between −15.8‰ and–26.3‰ are indicativeof a mixed diet of both C3 and C4 plants. The generated multiproxy data from dung samples can provide areliable counterpart to modern data for the interpretation of the palaeoecology in relation to thepalaeoherbivory and palaeodietary analysis in the region. This study also provides a basis to distinguishbetween wild and domesticated herbivores by analyzing coprolites and cultural sediments in archaeologicalsites