Hexbyte Glen Cove Cucurbit downy mildew pathogen has two genetically distinct host-adapted clades

Posted on October 28, 2020October 28, 2020 by Sharie Serna

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Field work in North Carolina Credit: E. C. Wallace, K. N. D’Arcangelo, and L. M. Quesada-Ocampo

Cucurbit downy mildew is a devastating disease for the United States cucurbit industry, which includes cucumbers, watermelon, squash, and pumpkin. The disease has caused major losses in North Carolina, which has significant cucumber and watermelon acreage. To help growers better manage this disease, a group of plant pathologists at North Carolina State University sought to better understand the biology of the pathogen that causes downy mildew.

They determined that the causal pathogen, Pseudoperonospora cubensis, has two genetically distinct host-adapted clades and also found that wild cucurbits can serve as reservoirs for this pathogen. Clade 1 isolates more frequently infect squash, pumpkin, and watermelon while clade 2 impacted cucumber and cantaloupe. They also found that evidence of recombination in clade 1 isolates but not clade 2 isolates.

“Overall, our findings have important implications for disease management because clade-specific factors such as host susceptibility and inoculum availability of each clade by region may influence pathogen outbreaks in different commercial cucurbits, timing of fungicide applications, and phenotyping for host resistance breeding efforts,” explained lead author Emma Wallace.

“It was surprising to us to find two host-adapted clades with such distinct genetic differentiation and only one clade showing evidence of recombination. We were also surprised that wild cucurbits can become readily infected by one or both clades, especially since some of those wild cucurbits are widespread in the United States and some are perennial,” added co-author Kimberly D’Arcangelo.

While previous research had shown evidence of two subpopulations within the pathogen, none were able to identify the main factors underlying those populations due to sampling limitations. Using a population genetics approach, Wallace and her colleagues applied a robust and standardized sampling strategy to investigate P. cubensis populations that infect wild cucurbit hosts.

“Our findings will have significant impacts on the adoption of crop-specific management practices,” said corresponding author Lina Quesada. “Current disease management recommendations are provided under the assumption that P. cubensis isolates were somewhat uniform. However, this paper and related projects have revealed that the two clades can have important biological differences, such as host preference, that are relevant when thinking about how to manage disease.”

Moving forward, plant pathologists will have to provide crop-specific recommendations as opposed to using the same approach for all cucurbit crops infected with downy mildew. For more information, read “Population Analyses Reveal Two Host-Adapted Clades of Pseudoperonospora cubensis, the Causal Agent of Cucurbit Downy Mildew, on Commercial and Wild Cucurbits” published in the September issue of Phytopathology.

More information:
E. C. Wallace et al, Population Analyses Reveal Two Host-Adapted Clades of Pseudoperonospora cubensis, the Causal Agent of Cucurbit Downy Mildew, on Commercial and Wild Cucurbits, Phytopathology (2020). DOI: 10.1094/PHYTO-01-20-0009-R

Provided by
American Phytopathological Society

Citation:
Cucurbit downy mildew pathogen has two genetically distinct host-adapted clades (2020, October 27)
retrieved 28 October 2020
from https://phys.org/news/2020-10-cucurbit-downy-mildew-pathogen-genetically.html

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Hexbyte Glen Cove OSIRIS-REx spacecraft goes for early stow of asteroid sample

Posted on October 27, 2020October 27, 2020 by Zonia Howe

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This illustration shows NASA’s OSIRIS-REx spacecraft stowing the sample it collected from asteroid Bennu on Oct. 20, 2020. The spacecraft will use its Touch-And-Go Sample Acquisition Mechanism (TAGSAM) arm to place the TAGSAM collector head into the Sample Return Capsule (SRC). Credit: NASA/University of Arizona, Tucson

NASA’s OSIRIS-REx mission is ready to perform an early stow on Tuesday, Oct. 27, of the large sample it collected last week from the surface of the asteroid Bennu to protect and return as much of the sample as possible.

On Oct. 22, the OSIRIS-REx mission team received images that showed the spacecraft’s collector head overflowing with material collected from Bennu’s surface—well over the two-ounce (60-gram) mission requirement—and that some of these particles appeared to be slowly escaping from the collection head, called the Touch-And-Go Sample Acquisition Mechanism (TAGSAM).

A mylar flap on the TAGSAM allows material to easily enter the collector head, and should seal shut once the particles pass through. However, larger rocks that didn’t fully pass through the flap into the TAGSAM appear to have wedged this flap open, allowing bits of the sample to leak out.

Because the first sample collection event was so successful, NASA’s Science Mission Directorate has given the mission team the go-ahead to expedite sample stowage, originally scheduled for Nov. 2, in the spacecraft’s Sample Return Capsule (SRC) to minimize further sample loss.

“The abundance of material we collected from Bennu made it possible to expedite our decision to stow,” said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, Tucson. “The team is now working around the clock to accelerate the stowage timeline, so that we can protect as much of this material as possible for return to Earth.”

Unlike other spacecraft operations where OSIRIS-REx autonomously runs through an entire sequence, stowing the sample is done in stages and requires the team’s oversight and input. The team will send the preliminary commands to the spacecraft to start the stow sequence and, once OSIRIS-REx completes each step in sequence, the spacecraft sends telemetry and images back to the team on Earth and waits for the team’s confirmation to proceed with the next step.

Signals currently take just over 18.5 minutes to travel between Earth and the spacecraft one-way, so each step of the sequence factors in about 37 minutes of communications transit time. Throughout the process, the mission team will continually assess the TAGSAM’s wrist alignment to ensure the collector head is properly placed in the SRC. A new imaging sequence also has been added to the process to observe the material escaping from the collector head and verify that no particles hinder the stowage process. The mission anticipates the entire stowage process will take multiple days, at the end of which the sample will be safely sealed in the SRC for the spacecraft‘s journey back to Earth.

“I’m proud of the OSIRIS-REx team’s amazing work and success to this point,” said NASA’s Associate Administrator for Science Thomas Zurbuchen. “This mission is well positioned to return a historic and substantial sample of an asteroid to Earth, and they’ve been doing all the right things, on an expedited timetable, to protect that precious cargo.”

Citation:
OSIRIS-REx spacecraft goes for early stow of asteroid sample (2020, October 26)
retrieved 27 October 2020
from https://phys.org/news/2020-10-osiris-rex-spacecraft-early-stow-asteroid.html

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Hexbyte Glen Cove On-surface synthesis of graphene nanoribbons could advance quantum devices

Posted on October 27, 2020October 27, 2020 by Georgianna Mayoral

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Scientists synthesized graphene nanoribbons, shown in yellow, on a titanium dioxide substrate, in blue. The lighter ends of the ribbon show magnetic states. The inset drawing shows how the ends have up and down spin, suitable for creating qubits. Credit: ORNL, U.S. Dept. of Energy

An international multi-institution team of scientists has synthesized graphene nanoribbons—ultrathin strips of carbon atoms—on a titanium dioxide surface using an atomically precise method that removes a barrier for custom-designed carbon nanostructures required for quantum information sciences.

Graphene is composed of single-atom-thick layers of carbon taking on ultralight, conductive and extremely strong mechanical characteristics. The popularly studied material holds promise to transform electronics and information science because of its highly tunable electronic, optical and transport properties.

When fashioned into nanoribbons, graphene could be applied in nanoscale devices; however, the lack of atomic-scale precision in using current state-of-the-art “top-down” synthetic methods—cutting a graphene sheet into atom-narrow strips—stymie graphene’s practical use.

Researchers developed a “bottom-up” approach—building the graphene nanoribbon directly at the atomic level in a way that it can be used in specific applications, which was conceived and realized at the Center for Nanophase Materials Sciences, or CNMS, located at the Department of Energy’s Oak Ridge National Laboratory.

This absolute precision method helped to retain the prized properties of graphene monolayers as the segments of graphene get smaller and smaller. Just one or two atoms difference in width can change the properties of the system dramatically, turning a semiconducting ribbon into a metallic ribbon. The team’s results were described in Science.

ORNL’s Marek Kolmer, An-Ping Li and Wonhee Ko of the CNMS’ Scanning Tunneling Microscopy group collaborated on the project with researchers from Espeem, a private research company, and several European institutions: Friedrich Alexander University Erlangen-Nuremberg, Jagiellonian University and Martin Luther University Halle-Wittenberg.

ORNL’s one-of-a-kind expertise in scanning tunneling microscopy was critical to the team’s success, both in manipulating the precursor material and verifying the results.

“These microscopes allow you to directly image and manipulate matter at the atomic scale,” Kolmer, a postdoctoral fellow and the lead author of the paper, said. “The tip of the needle is so fine that it is essentially the size of a single atom. The microscope is moving line by line and constantly measuring the interaction between the needle and the surface and rendering an atomically precise map of surface structure.”

In past graphene nanoribbon experiments, the material was synthesized on a metallic substrate, which unavoidably suppresses the electronic properties of the nanoribbons.

“Having the electronic properties of these ribbons work as designed is the whole story. From an application point of view, using a metal substrate is not useful because it screens the properties,” Kolmer said. “It’s a big challenge in this field—how do we effectively decouple the network of molecules to transfer to a transistor?”

The current decoupling approach involves removing the system from the ultra-high vacuum conditions and putting it through a multistep wet chemistry process, which requires etching the metal substrate away. This process contradicts the careful, clean precision used in creating the system.

To find a process that would work on a nonmetallic substrate, Kolmer began experimenting with oxide surfaces, mimicking the strategies used on metal. Eventually, he turned to a group of European chemists who specialize in fluoroarene chemistry and began to home in on a design for a chemical precursor that would allow for synthesis directly on the surface of rutile titanium dioxide.

“On-surface synthesis allows us to make materials with very high precision and to achieve that, we started with molecular precursors,” Li, a senior author of the paper who led the team at CNMS, said. “The reactions we needed to obtain certain properties are essentially programmed into the precursor. We know the temperature at which a reaction will occur and by tuning the temperatures we can control the sequence of reactions.”

“Another advantage of on-surface synthesis is the wide pool of candidate materials that can be used as precursors, allowing for a high level of programmability,” Li added.

The precise application of chemicals to decouple the system also helped maintain an open-shell structure, allowing researchers atom-level access to build upon and study molecules with unique quantum properties. “It was particularly rewarding to find that these graphene ribbons have coupled magnetic states, also called quantum spin states, at their ends,” Li said. “These states provide us a platform to study magnetic interactions, with the hope of creating qubits for applications in quantum information science.” As there is little disturbance to magnetic interactions in carbon-based molecular materials, this method allows for programming long-lasting magnetic states from within the material.

Their approach creates a high-precision ribbon, decoupled from the substrate, which is desirable for spintronic and quantum information science applications. The resulting system is ideally suited to be explored and built upon further, possibly as a nanoscale transistor as it has a wide bandgap, across the space between electronic states that is needed to convey an on/off signal.

More information:
Marek Kolmer et al, Rational synthesis of atomically precise graphene nanoribbons directly on metal oxide surfaces, Science (2020). DOI: 10.1126/science.abb8880

Citation:
On-surface synthesis of graphene nanoribbons could advance quantum devices (2020, October 26)

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Hexbyte Glen Cove Floating gardens: More than just a pretty place

Posted on October 27, 2020October 27, 2020 by Gaylene Catt

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Floating garden in summer. Credit: Abigail Heath.

Boulder, Colo., U.S.: Floating gardens sound so idyllic. Now, a study proves that they are more than just a pretty place. The study, by researchers at Illinois State University, demonstrates that such constructed gardens can have a measurable, positive impact on water quality.

Floating gardens are essentially rafts built on a frame of plastic caging, wrapped in coconut husks, and filled in with native plantings. As plants grow, they extend their roots into the water, growing hydroponically. On Chicago’s North Branch of the Chicago River, non-profit Urban Rivers and partners are developing a mile-long, floating eco-park. Dubbed the Wild Mile, the re-development of this former industrial canal is Urban Rivers’ flagship project. As part of the park, floating gardens, attached to shore, are being installed.

The primary intent of the floating gardens is beautification. But the Illinois State team, from the University’s Department of Geology, Geography, and the Environment, saw an ideal setup for a controlled experiment. “We got involved because it’s the perfect opportunity to see if there’s an impact on water quality,” explains lead author Abigail Heath.

Heath will present the results of the study in an online talk on Tuesday from 10:45 to 11:00 a.m. EDT, during the Geological Society of America’s annual meeting.

Drone image showing setting and project surroundings. Credit Urban Rivers. Credit: Urban Rivers.

The study is novel: previous studies have explored floating gardens’ impact on water quality over time, primarily in wastewater treatment ponds, but not over space, in moving water. The project also meshes well with Urban Rivers’ broader goals. “The city is interested in water quality,” says Phil Nicodemus, Urban Rivers Director of Research. “Happily, Illinois State got involved.”

Starting in spring 2018, Heath and co-authors have sampled water immediately upstream and downstream of a narrow 3 meter by 50 meter floating garden installed along the shoreline. Samples are collected weekly, at the surface and from 0.3 meters deep, the depth where roots reach from the garden’s base into the water. Although the garden is set at the edge of Chicago’s urban core, water quality is also impacted by upstream agriculture. Analyses are focused on nutrients including nitrate as nitrogen, chloride, sulfate, and phosphate.

Could this small slice of human-made paradise improve water quality? An average of data collected over the course of the study show modest but definitive improvement. For example, nitrate as nitrogen dropped from 4.69 milligrams per liter in surface water just upstream of the garden to 4.43 milligrams per liter just downstream, a drop of about 1 percent. Phosphate was also lower downstream of the garden.

“Despite how small this garden was there was measurable improvement in water quality from upstream to downstream, especially for nitrates,” notes Heath. She and colleagues see this as a scalable model for how larger floating gardens might help remediate water in similar settings. “Even this tiny garden makes a difference,” she says.

More information:
60-4: Assessment of Floating Gardens to Improve the Water Quality of the Chicago River (10:45 a.m. EDT): gsa.confex.com/gsa/2020AM/meet … app.cgi/Paper/355783

Citation:
Floating gardens: More than just a pretty place (2020, October 26)
retrieved 27 October 2020
from https://phys.org/news/2020-10-gardens-pretty.html

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Hexbyte Glen Cove Good accessibility is good web page design

Posted on October 27, 2020October 27, 2020 by Michele Center

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Accessibility isn’t something that should be added onto a web page, it should be baked in.

With yesterday being International Day of People with Disability, accessibility advocates were been out in force to fight the good fight. My tip: for another twelve months, the message will go unheeded, again.

But this year, at least one castle have fallen to the forces of properly accessible web sites: Telstra announced that it is removing CAPTCHA from its web sites and will start to include accessibility requirements in tenders that the company issues for IT solutions in the future.

Kudos to Telstra for making the move, and I look forward to seeing what actions the giant Australian telco takes to handle spam in its comment threads and forums. Finding a replacement for CAPTCHA that keeps spam low, and is fully accessible, has been to this point as successful as attempting to locate a Lost City of Gold.

One article that passed by my eyes is found on the pages of AusRegistry, in it are ten website accessibility tips that should be done for every site that you work on.

In the list are basic tenets such as using valid markup, descriptive links, text to convey any meaning set out in images or colour, and adding useful alt tags for images; as well as some more useful tips such as using form labels so that screen readers can understand the context of a form, and making sure that there is enough contrast between foreground and background colours to cater for users that are colour blind.

A prime example of good web design being good accessibility practice is the recommendation to use semantic markup to structure HTML content. Not only does it help assistive technologies understand the structure of your content, properly organising a page with a hierarchical structure will make styling it with CSS easier, and allow the full usage of CSS clauses and selections.

One way to test the accessibility of your web site is to try to use it in a console browser, such as Lynx. Looking at your page in text-only mode has the added benefit of showing how your page looks to search engine spiders and bots. Need to know why it is best to show your main content up front and as much of the right/left hand columns, headers, and footers to the end? Lynx will show you why.

Another good test of accessibility, and one that is more often a never-ending vain of frustration, is trying to navigate a web site using only the keyboard. I did this on one of my machines for a number of months, and it showed that many designers decided that the humble taborder is not worth worrying about. Worry about it, you’ll never know when you’ll need it, and you’ll be helping out people that rely on it everyday.

To finish off the accessibility suggestion list were a couple of great ideas: captioning videos, a great idea, but one that can be painful in practice to implement; and providing alternate versions of PDF documents in HTML or RTF, as browsers such as Firefox and Chrome embed quick and simple PDF viewers, the accessibility extras offered by Adobe’s Reader software often to not make the switch.

The really annoying part with many of these suggestions though, is that they should not be part of an attempt to make sites accessible, they should be an ingrained technique for creating good web sites.

These simple ideas to create an accessible, structured, and valid w

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Hexbyte Glen Cove Take your app on the road, put it in a car

Posted on October 27, 2020October 27, 2020 by Augustine Mayoral

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Looking for a new market or adding a unique edge to your app? Then support for in-car usage could be just the ticket.

As jurisdictions clamp down on in-car usage of mobile phones, many drivers’ only interaction with their mobile devices is controlling Bluetooth audio playback from steering wheel controls, if they are lucky enough to have them.

Auto makers are taking different tacts with mobile technology usage: BMW has its ConnectedDrive connectivity, Audi has an interesting take with an augmented-reality manual, and Ford has its SYNC platform.

Over the weekend, TechRepublic was invited to take part in a 24-hour hackathon with Ford to try out its AppLink system, which allows for regular iOS and Android apps to integrate with the SYNC’s voice recognition and the vehicle console monitor. Ironically, although SYNC is made by Microsoft and runs Windows Embedded Automotive, there is no support for Windows Phone — and support for BlackBerry devices recently ended.

The process of putting AppLink into an app is relatively straightforward; once registered on Ford’s developer portal, for Android, it is then a case of downloading the library into your project and using the handful of APIs available to control the car’s display text and create audible alerts.

Currently, the API is rather limited, with display text only allowing approximately 20 characters on two lines. The text does not scroll, but Ford has a beta of its next edition of AppLink that adds support for this. Consequently, the easiest way to inform the driver is via text to speech.

This is a handy feature, as the system used by Ford does not have a display within the driver’s instrumentation in the dash, like that seen here, and the screen mounted in the dash is not touchscreen, instead having to be controlled with a plethora of buttons.

It’s a system that reeks of Microsoft-design principles, and after a weekend of using the system, I am glad I will no longer have to mash the menu button to access commands in the app I was creating, rather than having the commands and menus relevant to the app on-screen, or a simple one menu button press away. This should be negated by the use of voice commands, but the test units I was working on only had US English available, and found my Australian accent and word usage rather confusing.

A unique aspect of apps that use AppLink is that Ford dictates that the app have a lock screen when it is paired with the car. It makes sense and is regarded as a safety feature — force the driver to keep their hands on the wheel and navigate the app without needing to touch the paired device. It does mean that the discoverability of app features sinks to rock bottom, and, as I mentioned previously, going into the menu of an app is an arduous task. Hopefully the next version of AppLink will rectify these shortcomings.

With all that said, the idea of extending existing apps into cars is a good one, and it would be nice if there were a common platform to allow app developers a single target to aim at. To that end, earlier this year, Ford open sourced AppLink to the GENIVI Alliance, which is a consortium of auto manufacturers and technology vendors looking to produce a Linux-based in-car infotainment system. But given the slow pace with which the auto industry moves compared to the technology industry, I wouldn’t be expecting any Earth-shattering announcements anytime soon.

At the end of the hackathon, a motley collection of apps were produced, from geo-fenced reminders to bush fire warnings systems, to apps that turned an iPhone into a dashcam that uploaded videos to YouTube.

The winner of the “best new app” category for an app created within the hackathon’s 24-hour duration was the team from MYOB, which used its company’s API to create an app for mobile workers to receive and control job items, and even send invoices upon job completion while out on the road servicing customers.

Taking home the gong in the “best existing app” category for integration AppLink into an already built app was the crew from Millipede, who took their car log book app and added in AppLink’s voice commands.

Besides the sleep deprivation experienced from the event, the overwhelming feeling was how much better every app’s user experience could be with a couple more features added to SYNC.

App makers are not likely to hit the monetisation jackpot with an in-car app,

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Hexbyte Glen Cove Navigating the morass of systemd, NetworkManager, and GNOME 3.10

Posted on October 27, 2020October 27, 2020 by Elida Mischke

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The world of Linux: Where making a laptop engage its wired connection when attached to a dock is an exercise in frustration.

As a recent beneficiary of a laptop upgrade, I took the opportunity to re-examine my choice of Linux distribution that I use day-to-day. After a year of Arch Linux, and that distro deciding to move to the systemd init system, plus the depreciation of the far from impressive PreUpgrade tool in favour of a new upgrade experience on Fedora called FedUp, I decided that I would return to the land of Fedora.

Arch was, and still is, a very good Linux distribution — the community is good, and the Arch User Repository is as good as people say it is. In retrospect though, it was the move to systemd that made me decide to move on from Arch.

Changing an init system on an already installed system is just asking for trouble, but eventually when a confluence of issues regarding GNOME and Arch made it impossible to continue without making the transition to systemd, I duly followed. The process was not as torturous as it could be, as I’d already made the switch previously at home with my Gentoo box, so I had some idea what I was in for.

But after transitioning over to systemd, it is a brave user that blows away all the remnants of the old init system that they were using, as there is generally one or two services that do not work with systemd, or are so tightly integrated with the existing init system that you may need to wait a release or two to get systemd compatibility.

In essence, what you end up with is a hybrid system that doesn’t know whether it is Frankenstein’s monster or Kuato from Total Recall. And thanks to my home Gentoo box, I’d already had one of those things in my life already, hence I decided to go full systemd, and give Fedora another shot.

At the same time that I was returning from the world of Arch Linux to Fedora, it had acquired a dock to go along with the new Lenovo laptop — even though it is a laptop, it does spend most of its time attached to monitors, keyboards, and other peripherals, so it made sense to end the ritual of plugging and unplugging the same cords at the start and end of each day.

Everything on the dock worked as it should, with two notable exceptions: having a network cable connected to the ethernet port on the dock did not fire a cable connection event, and it is impossible to record from auxiliary audio line on the dock if a pair of headphones are connected to the laptop itself.

How things used to be in GNOME 3.8

Image: Chris Duckett/TechRepublic

The latter I have slowly turned to live with, because it is not often that I need to record from the auxiliary line, and is easily fixed by removing the headphones from the jack.

The former issue, despite the effect that a lack of connectivity has on modern desktop usage, was actually quite easily solved by quickly shooting the mouse to the top right of the desktop and clicking on the network icon of my GNOME 3 desktop to force enabling of the wired connection.

It sounds like a lot of movement, but it was really less than a second of work, and it wasn’t too much trouble — if it was a bigger deal, I would have investigated why the connection was not being enabled at boot each day.

What forced me to dig deeper was the attraction of trying out Fedora 20, Heisenbug, which was currently in beta.

As with every Fedora release, an upgrade to the latest release of GNOME occurs, and time I was updated to GNOME 3.10.

New and “improved” network settings in GNOME 3.10

Image: Chris Duckett/TechRepublic

GNOME developers will do what GNOME developers do so well, and that means removing features with startling regularity. Consequently that little icon that I had relied upon at the start of each day was removed, and in its place was a wi-fi icon — wired connectivity had been exiled to the GNOME network settings panel.

Now I was forced to work dig into the inner workings of network connectivity involving NetworkManager and systemd.

A natural place to start would be the configuration file for NetworkManager, /etc/NetworkManager/NetworkManager.conf, but it contained only a one line reference to a Red Hat plugin, ifcfg-rh, that meant that all network configuration scripts would be stored in /etc/sysconfig/network-scripts/

Thanks to the changes in udev-197, network interfaces in Linux now have “predictable” names, gone is the eth0, eth1 names of old, and in its place is enp0s25 (in my particular piece of hardware). Therefore, in order to configure this interface, we need to edit /etc/sysconfig/network-scripts/ifcfg-enp0s25.

To get the network interface to come up on boot, all that is needed is to add ONBOOT=yes to the file.

It’s not much work once you know where to look, but it is not as simple as toggling a default connection status in the graphical interface that used to exist in GNOME, nor is it quite as straight forward as manipulating network settings Gentoo, but much of that can probably be put down to familiarity with that distro.

And if NetworkManager ever gives you too much grief, you can always throw it away and replace it with wicd.

Update: Adam Will

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Hexbyte Glen Cove Thousands of seals found dead in Namibia

Posted on October 26, 2020October 26, 2020 by Leigha Schewe

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An estimated 7,000 Cape fur seals have been discovered dead at a breeding colony in central Namibia, scientists said on Saturday.

Conservationist Naude Dreyer of the charity Ocean Conservation Namibia began noticing dead seals littering the sandy beaches of the Pelican Point colony near Walvis Bay city in September.

Then in the first two weeks of October he found large numbers of seal foetuses at the colony, Dr. Tess Gridley from the Namibian Dolphin Project told AFP by phone.

Fur seals normally give birth between mid-November and mid-December.

Gridley estimated that between 5,000 and 7,000 female seals had miscarried young with more still being found.

The cause of the mass die off is yet to be established but scientists suspect anything from pollutants or bacterial infection to malnutrition.

Some of the dead females found were “thin-looking, emaciated, with very little fat reserves”, said Gridley.

Scientists are collecting samples for testing.

In 1994 some 10,000 seals died and 15,000 foetuses were aborted in a mass die off that was linked to starvation suspected to have resulted from a shortage of fish as well as from a bacterial infection at another breeding colony, the Cape Cross, some 116 kilometres (72 miles) north of the central tourist town Swakopmund.

Annely Haiphene, executive director in the Ministry of Fisheries and Marine resources, told AFP she suspected the seals died from “lack of food” but will wait the outcome of the tests.

Citation:
Thousands of seals found dead in Namibia (2020, October 24)
retrieved 26 October 2020
from https://phys.org/news/2020-10-thousands-dead-namibia.html

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Hexbyte Glen Cove Metal deposits from Chinese coal plants end up in the Pacific Ocean, research shows

Posted on October 26, 2020October 26, 2020 by Margherita Center

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Credit: CC0 Public Domain

Emissions from coal-fired power plants in China are fertilizing the North Pacific Ocean with a metal nutrient important for marine life, according to new findings from a USC-led research team.

The researchers believe these metals could change the ocean ecosystem, though it’s unclear whether it would be for better or worse.

The study shows that smoke from power plants carries iron and other metals to the surface waters of the North Pacific Ocean as westerly winds blow emissions from Asia to North America. Peak measurements show that up to nearly 60% of the iron in one vast swath of the northern part of the ocean emanates from smokestacks.

“It has long been understood that burning fossil fuels alters Earth’s climate and ocean ecosystems by releasing carbon dioxide into the atmosphere,” said Seth John, lead author of the study and an assistant professor of Earth sciences at the USC Dornsife College of Letters, Arts and Sciences. “This work shows fossil fuel burning has a side effect: the release of iron and metals into the atmosphere that carry thousands of miles and deposit in the ocean where they can impact marine ecosystems.”

“Certain metal deposits could help some marine life thrive while harming other life,” he added. “There are inevitable tradeoffs when the ocean water’s chemistry changes.”

The study was published on Thursday in the Proceedings of the National Academy of Sciences. Researchers from USC, Columbia University, University of Washington, MIT and the University of Hawaii, among others, collaborated.

USC-led team confirms that ocean metals stem from China

While wind-blown mineral dust from deserts has long been considered an important source of iron to open ocean waters, the new study shows how manmade sources contribute important micronutrients that plankton and algae need. Moreover, the study shows how fossil fuel burning affects not only global warming but marine environments, too.

Previous studies have shown widely divergent estimates about how much iron is carried from various land-based sources to the ocean, especially from anthropogenic sources. Iron is a key limiting factor for marine productivity for about one-third of the world’s oceans.

Instead, the USC-led research team measured metals in surface seawater. They focused on a remote part of the Pacific Ocean, hundreds of miles north of Hawaii and about midway between Japan and California. The region is downwind of industrial emissions in east Asia.

In May 2017, they boarded a research vessel and took water samples along a north-south transect at latitudes between 25 degrees and 42 degrees north. They found peak iron concentrations in about the middle, which corresponded with a big wind event over east Asia one month before. The peak iron concentrations are about three times greater than background ocean measurements, the study shows.

In addition, the scientists found elevated lead concentrations coincided with the iron hot spots. Other research has shown that most of the lead at the ocean surface comes from manmade sources, including cement plants, coal-fired power plants and metal smelters.

Moreover, the metals in the seawater samples bear telltale traces of Chinese industrial sources, the study says.

“When we collected samples in the ocean, we found that the iron isotope and lead isotope ‘fingerprints’ from seawater matched those of anthropogenic pollution from Asia,” said Paulina Pinedo-Gonzalez, a USC post-doctoral scientist and study author who is now at the Lamont-Doherty Earth Observatory at Columbia University.

Finally, the scientists also ruled out upwelling from the deep ocean as a source of the metals by testing water samples at depth.

What does the abundance of metals mean for marine life?

The study has important implications for marine life in the ocean. The North Pacific notably lacks iron, a key micronutrient, so an influx of metals and other substances can help build the foundation for a new ecosystem—a ‘good news, bad news’ outcome for Earth.

“Microscopic iron-containing particles released during coal burning impacts algae growth in the ocean, and therefore the entire ecosystem for which algae form the base of the food chain,” John explained. “In the short term, we might think that iron in pollution is beneficial because it stimulates the growth of phytoplankton, which then take carbon dioxide out of the atmosphere as they grow to offset some of the carbon dioxide released during the initial burning process.

“However, it’s totally unsustainable as a long-term geoengineering solution because of the deleterious effects of pollution on human health. Thus, the take-home message is perhaps a better understanding of an unintended side effect of coal burning and the ways in which that can impact ocean ecosystems thousands of miles away.”

More information:
Paulina Pinedo-González et al. Anthropogenic Asian aerosols provide Fe to the North Pacific Ocean, Proceedings of the National Academy of Sciences (2020). DOI: 10.1073/pnas.2010315117

Citation:
Metal deposits from Chinese coal plants end up in the Pacific Ocean, research shows (2020, October 23)

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Hexbyte Glen Cove Coastal permafrost more susceptible to climate change than previously thought

Posted on October 26, 2020October 26, 2020 by Zonia Kazmierczak

Hexbyte Glen Cove

Micaela Pedrazas (left) and Cansu Demir, both graduate students at The University of Texas at Austin Jackson School of Geosciences, examining an exposed side of an ice wedge polygon, which was uncovered by erosion and melting. An ice lens is visible to the right of Demir. Credit: Bayani Cardenas

If you flew from the sea towards the land in the north slope of Alaska, you would cross from the water, over a narrow beach, and then to the tundra. From the air, that tundra would look like a landscape of room-sized polygonal shapes. Those shapes are the surface manifestations of the ice in the frozen ground below, a solidified earth known as permafrost.

Scientists long believed the solid permafrost extended offshore: from the tundra, below that narrow beach and below the seafloor declining at a gentle slope. They viewed that permafrost like solid brick, locking the subsurface—and the vast amounts of carbon it holds—in place.

But new research led by Micaela Pedrazas, who earned her masters at The University of Texas at Austin Jackson School of Geosciences working with Professor Bayani Cardenas, has upended that paradigm. They found permafrost to be mostly absent throughout the shallow seafloor along a coastal field site in northeastern Alaska. That means carbon can be released from coastline sources much more easily than previously thought.

The study was published in Science Advances on Oct. 23 with coauthors from the Jackson School and UT’s Marine Science Institute.

Using a geophysical technique called electrical resistivity imaging, the researchers mapped the subsurface beneath Kaktovik Lagoon along the northeastern coast of Alaska over the course of three years.

An aerial image of ice wedge polygons next to Kaktovik Lagoon. The polygons are signs of ice in the frozen ground below, a solidified earth known as permafrost. Credit: Nathan Sonderman

The results were unexpected. The beach and seafloor were entirely ice-free down to at least 65 feet. On the tundra itself, ice-rich permafrost was detected in the top 16 feet, but below that, the subsurface their imaging mapped was also ice-free.

“This leads to a new conceptual model,” Pedrazas said.

Permafrost is found in cold climates that remain frozen during the course of the year. Scientists have been tracking the impact of a warming climate on permafrost because as it melts, permafrost releases its stores of frozen carbon into the atmosphere as methane and carbon dioxide, contributing to climate change.

Permafrost studies have almost exclusively focused on the region beneath the tundra. Because it’s not easy to work in such remote locations and under harsh weather conditions, the transition from sea to shore has been largely ignored.

“This study tells us that the coastline is much more complicated than we thought,” said co-author Jim McClelland from UT’s Marine Science Institute. “It opens up the possibility for routes of water exchange that we weren’t thinking about.”

Ph.D. student Cansu Demir and Professor Bayani Cardenas, both from The University of Texas Jackson School of Geosciences, installing a mini-groundwater well in the bed of Kaktovik Lagoon. Credit: Micaela Pedrazas

Besides global considerations, the work has local impacts. The communities along the coast, most of whom are Inupiat, live on the permafrost. As the permafrost thaws, it accelerates coastal erosion, which carves away at the land on which homes and infrastructure stand. In the Kaktovik region, erosion can be as great as 13 feet per year.

“Their cultural heritage and their welfare is integrated and intricately linked to their environment,” Cardenas said. “There’s an immediate need to understand what’s happening in these lagoons.”

The new paradigm requires reimagining the coastal Arctic ecosystem as well. Liquid groundwater means that carbon and nutrients can move between the tundra and the lagoon. It also means that saltwater can move beneath the tundra, potentially affecting freshwater sources.

Paul Overduin, who wasn’t involved in the research, but who studies permafrost at Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, said that this work is the first step in understanding permafrost‘s transition from sea to shore.

“As is often the case, when we start looking at something people don’t know much about, you open up a whole bunch of questions that needed to be looked at,” he said. “That’s what’s really exciting here.”

More information:
“Absence of ice-bonded permafrost beneath an Arctic lagoon revealed by electrical geophysics” Science Advances (2020). advances.sciencemag.org/lookup … .1126/sciadv.abb5083

Citation:
Coastal permafrost more susceptible to climate change than previously thought (2020, October 23)
retrieved 26 October 2020
from https://phys.org/news/2020-10-coastal-permafrost-susceptible-climate-previously.html

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