The force needed to move an atom on a surface

Manipulation of individual atoms and molecules by scanning probe microscopy offers the ability of controlled assembly at the single-atom scale. However, the driving forces behind atomic manipulation have not yet been measured. We used an atomic force microscope to measure the vertical and lateral forces exerted on individual adsorbed atoms or molecules by the probe tip. We found that the force that it takes to move an atom depends strongly on the adsorbate and the surface. Our results indicate that for moving metal atoms on metal surfaces, the lateral force component plays the dominant role. Furthermore, measuring spatial maps of the forces during manipulation yielded the full potential energy landscape of the tip-sample interaction.     

Theodor Hellbrugge: 85 years of age - Ad multos transannos, sanos, fortunatos et beatos

We honor Theo Hellbrugge's acclaimed endeavors in the rehabilitation, or rather the prehabilitation of handicapped children. So far, he has focused on obvious handicaps, and we trust that he will include concern for everybody's silent handicaps in the future by screening for abnormal variability inside the physiological range. Therein, we introduce cis- and trans-years, components of transdisciplinary spectra that are novel for biology and also in part for physics. These components have periods, respectively, shorter and longer than the calendar year, with a counterpart in magnetoperiodism. Transyears characterize indices of geomagnetic activity and the solar wind's speed and proton density. They are detected, alone or together with circannuals, in physiology as well as in pathology, as illustrated for sudden cardiac death and myocardial infarction, a finding calling for similar studies in sudden infant death syndrome (SIDS). As transyears can beat with circannuals, and depend on local factors, their systematic mapping in space and time by transdisciplinary chronomics may serve a better understanding of their putative influence upon the circadian system. Longitudinal monitoring of blood pressure and heart rate detects chronome alterations underlying cardiovascular disease risk, such as that of myocardial infarction and sudden cardiac death. The challenge is to intervene in a timely fashion, preferably at birth, an opportunity for pediatricians in Theo Hellbrugge's footsteps.     

The impact of environmental factors on early stage Andosol development south of Vatnajökull,Iceland

Icelandic soils develop in a dynamic environment affected by both natural processes and anthropogenic impacts. We present an extensive investigation of soil mineralogy and pedogenesis in a disturbed (i.e., by solifluction) pedon under such conditions. The study focuses on two distinct tephra layers, a rhyolitic tephra from the Öræfajökull eruption in 1362 CE (Ö1362) and a basaltic Veiðivötn tephra from 1477 CE (V1477). Both tephra layers form an important parent material in the study area south of Vatnajökull, Iceland. The Andosol developed from tephra and aeolian material, rich in volcanic glass. The pH (H₂O) values were between 5.5 and 6.6 and clay mineralogy displayed a predominance of allophanic material in both soil and tephra. The pedon can be seen in its early stage of chemical weathering and soil development. Despite the overall predominance of non- and poorly-crystalline short-range order secondary materials and Fe (hydr)oxides in the clay-size fraction, we found indication of smectite. High exchangeable Ca²⁺ and Mg²⁺ concentrations reflect enhanced aeolian input of volcanic material, while elevated exchangeable-Na⁺ concentrations are most likely caused by the oceanic composition of precipitation. The impact of erosion and aeolian processes on pedogenesis seemed to be higher between the deposition of Ö1362 and V1477, than in the soils above. Both, soil and tephra layers appeared disturbed by erosion–deposition processes over time. Characterised by a significantly coarser particle size composition, low soil organic carbon (SOC) content, and a more diverse mineralogy, a distinct fluvial sediment layer at 10–30 cm depth appeared sharply contrasting to the other soil layers in the profile. This possibly reflects the diverse composition of glaciofluvial material from a landslide originating from a Kvíárjökull moraine in the north. Changed weathering patterns and properties in the soils above the Ö1362 tephra indicated soil degradation following the deposition of the rhyolitic tephra.     

Variability of certain chemotypes in three accessions of German chamomile (Matricaria chamomilla L.)

In 203 analyzed chamomile plants, several compounds appreciated for their medicinal value, were evaluated qualitatively and quantitatively. α-Bisabolol and its oxides A and B were measured by gas chromatography; matricine as a precursor of chamazulene, was assessed semi-quantitatively by matching visually thin layer chromatography bands with a concentration range of the pure substance and the flavonoids apigenin and apigenin-7-glycoside were quantified by high performance liquid chromatography. Mean values of all compounds were compared in the three chamomile accessions ‘Manzana’, ‘Lutea’ and ‘Hungarian 2’. Correlations between different substances over all data were calculated. Moreover, certain groups combining particular properties according to their desired purpose or specificity, were formed. Their incidence in the particular chamomile varieties was determined. ‘Manzana’, a tetraploid cultivar, exhibited the highest share of the valuable bisabolol–matricine-type and the lowest ratio of bisabolol-oxides to bisabolol. To develop ‘high-quality-populations’, defined individuals of this cultivar shall be selected for further breeding.     

Temperature sensitivity of young and old soil carbon – Same soil,slight differences in 13C natural abundance method,inconsistent results

Predictions of future climate change critically depend on the temperature sensitivity of soil organic carbon decomposition. One question of debate is whether temperature sensitivity differs between young or labile and old or more stable carbon pools. We re-analysed soil that has previously led to the conclusion that old soil carbon is more temperature sensitive. The re-analysis gave different results compared to the earlier study, most likely due to small differences in an otherwise very similar experimental approach. This study illustrates how conclusions may depend upon details of the experimental setting.     

Ultrafast laser-driven microlens to focus and energy-select mega-electron volt protons

We present a technique for simultaneous focusing and energy selection of high-current, mega-electron volt proton beams with the use of radial, transient electric fields (10(7) to 10(10) volts per meter) triggered on the inner walls of a hollow microcylinder by an intense subpicosecond laser pulse. Because of the transient nature of the focusing fields, the proposed method allows selection of a desired range out of the spectrum of the polyenergetic proton beam. This technique addresses current drawbacks of laser-accelerated proton beams, such as their broad spectrum and divergence at the source.     

Chondrosarcoma in a simmental cow: Clinical, ultrasonographic, radiographic and pathological findings

Clinical, ultrasonographic, radiographic and pathological findings of a chondrosarcoma diagnosed in an 8-year-old Simmental cow are reported. The primary site was located in the cartilage of the right scapula at the angulus cranialis. The tumour had already spread to the lungs at the time of diagnosis. This is the first report of a bovine scapula chondrosarcoma.     

Erratum to: Woody habitats promote pollinators and complexity of plant–pollinator interactions in homegardens located in rice terraces of the Philippine Cordilleras

Paddy and Water Environment -