171 articles from THURSDAY 26.11.2020

UAE mission to Mars on course to arrive in February 2021

Spacecraft known as Hope carries instruments designed to study the tenuous Martian atmosphereThe Emirates Mars Mission (EMM) is on course to arrive at the Red Planet on 9 February. A third and final major trajectory correction manoeuvre (TCM) was completed on 10 November. An additional minor TCM in December will tee it up for a Mars orbit insertion manoeuvre next year. Without the need for further...

Climate crisis making autumn leaves fall earlier, study finds

Report suggests tree growth will not store nearly as much carbon as scientists hopedGlobal heating appears to be making trees drop their leaves earlier, according to new research, confounding the idea that warmer temperatures delay the onset of autumn.The finding is important because trees draw huge amounts of carbon dioxide from the air and therefore play a key role in managing the climate....

Irreversible hotter and drier climate over inner East Asia

Mongolia's semi-arid plateau may soon become as barren as parts of the American Southwest due to a "vicious cycle" of heatwaves—that exacerbates soil drying, and ultimately produces more heatwaves—according to an international group of climate scientists.

A route for avoiding defects during additive manufacturing

Laser powder bed fusion is a dominant additive manufacturing technology that has yet to reach its potential. The problem facing industry is that tiny bubbles or pores sometimes form during the printing process, and these pores create weak spots in finished products.

New Hubble data explains missing dark matter

New data from the NASA/ESA Hubble Space Telescope provides further evidence for tidal disruption in the galaxy NGC 1052-DF4. This result explains a previous finding that this galaxy is missing most of its dark matter. By studying the galaxy's light and globular cluster distribution, astronomers have concluded that the gravity forces of the neighbouring galaxy NGC 1035 stripped the dark matter from...

A chimeric gene paternally instructs female sex determination in the haplodiploid wasp Nasonia

Various primary signals direct insect sex determination. In hymenopteran insects, the presence of a paternal genome is needed to initiate female development. When absent, uniparental haploid males develop. We molecularly and functionally identified the instructor sex-determination gene, wasp overruler of masculinization (wom), of the haplodiploid wasp Nasonia vitripennis. This gene contains a...

Abl and Canoe/Afadin mediate mechanotransduction at tricellular junctions

Epithelial structure is generated by the dynamic reorganization of cells in response to mechanical forces. Adherens junctions transmit forces between cells, but how cells sense and respond to these forces in vivo is not well understood. We identify a mechanotransduction pathway involving the Abl tyrosine kinase and Canoe/Afadin that stabilizes cell adhesion under tension at tricellular junctions...

Abrupt shift to hotter and drier climate over inner East Asia beyond the tipping point

Unprecedented heatwave-drought concurrences in the past two decades have been reported over inner East Asia. Tree-ring–based reconstructions of heatwaves and soil moisture for the past 260 years reveal an abrupt shift to hotter and drier climate over this region. Enhanced land-atmosphere coupling, associated with persistent soil moisture deficit, appears to intensify surface warming and...

Capturing roaming molecular fragments in real time

Since the discovery of roaming as an alternative molecular dissociation pathway in formaldehyde (H2CO), it has been indirectly observed in numerous molecules. The phenomenon describes a frustrated dissociation with fragments roaming at relatively large interatomic distances rather than following conventional transition-state dissociation; incipient radicals from the parent molecule self-react to...

Comment on "Forest microclimate dynamics drive plant responses to warming"

Zellweger et al. (Reports, 15 May 2020, p. 772) claimed that forest plant communities’ response to global warming is primarily controlled by microclimate dynamics. We show that community thermophilization is poorly explained by the underlying components of microclimate, and that global warming primarily controls the climatic lag of plant communities. Deconstructing the underlying components...

Critical instability at moving keyhole tip generates porosity in laser melting

Laser powder bed fusion is a dominant metal 3D printing technology. However, porosity defects remain a challenge for fatigue-sensitive applications. Some porosity is associated with deep and narrow vapor depressions called keyholes, which occur under high-power, low–scan speed laser melting conditions. High-speed x-ray imaging enables operando observation of the detailed formation process of...