1,410 research outputs found
Low-energy electron transmission imaging of clusters on free-standing graphene
We investigated the utility of free-standing graphene as a transparent sample
carrier for imaging nanometer-sized objects by means of low-energy electron
holography. The sample preparation for obtaining contamination-free graphene as
well as the experimental setup and findings are discussed. For incoming
electrons with 66 eV kinetic energy graphene exhibits 27% opacity per layer.
Hence, electron holograms of nanometer-sized objects adsorbed on free-standing
graphene can be recorded and numerically reconstructed to reveal the object's
shapes and distribution. Furthermore, a Moire effect has been observed with
free-standing graphene multi-layers
Attentional modulation of orthographic neighborhood effects during reading: Evidence from event-related brain potentials in a psychological refractory period paradigm
It is often assumed that word reading proceeds automatically. Here, we tested this assumption by recording event-related potentials during a psychological refractory period (PRP) paradigm, requiring lexical decisions about written words. Specifically, we selected words differing in their orthographic neighborhood size–the number of words that can be obtained from a target by exchanging a single letter–and investigated how influences of this variable depend on the availability of central attention. As expected, when attentional resources for lexical decisions were unconstrained, words with many orthographic neighbors elicited larger N400 amplitudes than those with few neighbors. However, under conditions of high temporal overlap with a high priority primary task, the N400 effect was not statistically different from zero. This finding indicates strong attentional influences on processes sensitive to orthographic neighbors during word reading, providing novel evidence against the full automaticity of processes involved in word reading. Furthermore, in conjunction with the observation of an underadditive interaction between stimulus onset asynchrony (SOA) and orthographic neighborhood size in lexical decision performance, commonly taken to indicate automaticity, our results raise issues concerning the standard logic of cognitive slack in the PRP paradigm
The Christmas Island Seamount Province, Indian Ocean: Origin of Intraplate Volcanism by Shallow Recycling of Continental Lithosphere?
The east-west-trending Christmas Island Seamount
Province (CHRISP, 1800x600 km) in the northeastern Indian
Ocean is elongated orthogonal to present-day plate motion,
posing the question if a mantle plume formed this volcanic
belt. Here we report the first age (Ar/Ar) and geochemical (Sr-
Nd-Hf-Pb DS isotopic data) from the CHRISP seamount
chain. A crude E-W age decrease from the Argo Basin (136
Ma), to the Eastern Wharton Basin (115-94 Ma) to the
Vening-Meinesz seamounts (96-64 Ma) to the Cocos-Keeling
seamounts (56-47 Ma) suggests spatial migration of melting.
Christmas Island, however, yields much younger ages (44-4
Ma), inconsistent with an age progression. The isotopic
compositions (e.g. 206Pb/204Pb = 17.3-19.3; 207Pb/204Pb = 15.49-
15.67; 143Nd/144Nd = 0.51220-0.51295; 176Hf/177Hf = 0.28246-
0.28319) range from enriched MORB (or “C”) to very
enriched mantle (EM1) type compositions more typical of
continental than oceanic volcanism. Lamproitic and
kimberlitic rocks from western Australia, India and other
continental areas, derived from metasomatized subcontinental
lithospheric mantle, could serve as the EM1 type endmembers.
The morphology, ages and chemical composition of the
CHRISP, combined with plate tectonic reconstructions, cannot
be easily explained within the framework of the mantle plume
hypotheses. We therefore propose that the seamounts are
derived through the recycling of continental lithosphere
(mantle ± lower crust) delaminated during the breakup of
Gondwana and brought to the surface at the former spreading
centers separating Argoland (western Burma), Greater India
and Australia
Moire structures in twisted bilayer graphene studied by transmission electron microscopy
We investigate imaging of moire structures in free-standing twisted bilayer
graphene (TBG) carried out by transmission electron microscopy (TEM) in
diffraction and in-line Gabor holography modes. Electron diffraction patterns
of TBG acquired at typical TEM electron energies of 80 - 300 keV exhibit the
diffraction peaks caused by diffraction on individual layers. However,
diffraction peaks at the scattering angles related to the periodicity of the
moire structure have not been observed in such diffraction patterns. We show
that diffraction on moire structure can create intense diffraction peaks if the
energy of the probing electrons is very low, in the range of a few tens of eV.
Experimental diffraction patterns of TBG acquired with low-energy electrons of
236 eV exhibiting peaks attributed to the moire structure periodicity are
shown. In holography mode, the intensity of the wave transmitted through the
sample and measured in the far-field can be enhanced or decreased depending on
the atomic arrangement, as for example AA or AB stacking. Thus, a decrease of
intensity in the far-field must not necessarily be associated with some
absorption inside the sample but can simply be a result of a particular atomic
arrangement. We believe that our findings can be important for exploiting
graphene as a support in electron imaging
How can family businesses survive disruptive industry changes? Insights from the traditional mail order industry
The present study investigates how family firms respond to disruptive industry changes. We aim to investigate which factors prevent or support family firms’ adoption of disruptive innovations in their industry and which mechanisms lead to more or less successful coping with disruptive change. Our analysis is based on 24 qualitative interviews with top executives and on secondary data from an industry in which disruptive innovations dramatically changed the way business was generated. The industry in question is the mail order industry, which, in its early days, disrupted the retail business. When the Internet and, with it, ecommerce started to disrupt the industry in the late 1990s, the industry was characterized by a high proportion of family firms and a low level of innovativeness. While incumbent firms had been very successful for decades, most of them were confronted with serious turbulence when new entrants started changing the face of the industry. Our findings show that different factors impact reactions to disruptive industry change in two different phases, namely, opportunity recognition and opportunity implementation. While some of the influencing factors are determined by industry factors, family influence may function for better or worse for incumbent firms. Specifically, we find that in firms with a family disruptor, a family member in a powerful position who drives the adoption of the new technology, hindrances can be overcome and firms tend to show more successful strategies when reacting to the disruptive industry change
Imaging the potential distribution of individual charged impurities on graphene by low-energy electron holography
While imaging individual atoms can routinely be achieved in high resolution
transmission electron microscopy, visualizing the potential distribution of
individually charged adsorbates leading to a phase shift of the probing
electron wave is still a challenging task. Low-energy electrons (30 - 250 eV)
are sensitive to localized potential gradients. We employed low-energy electron
holography to acquire in-line holograms of individual charged impurities on
free-standing graphene. By applying an iterative phase retrieval reconstruction
routine we recover the potential distribution of the localized charged
impurities present on free-standing graphene
- …