Hexbyte Glen Cove Webb team brings 18 dots of starlight into hexagonal formation

Hexbyte Glen Cove

This early Webb alignment image, with dots of starlight arranged in a pattern similar to the honeycomb shape of the primary mirror, is called an “image array.” Credit: NASA/STScI/J. DePasquale

The James Webb Space Telescope team continues to make progress in aligning the observatory’s mirrors. Engineers have completed the first stage in this process, called “Segment Image Identification.” The resulting image shows that the team has moved each of Webb’s 18 primary mirror segments to bring 18 unfocused copies of a single star into a planned hexagonal formation.

With the image array complete, the team has now begun the second phase of alignment: “Segment Alignment.” During this stage, the team will correct large positioning errors of the mirror segments and update the alignment of the secondary mirror, making each individual dot of starlight more focused. When this “global alignment” is complete, the team will begin the third phase, called “Image Stacking,” which will bring the 18 spots of light on top of each other.

“We steer the segment dots into this array so that they have the same relative locations as the physical mirrors,” said Matthew Lallo, systems scientist and Telescopes Branch manager at the Space Telescope Science Institute. “During global alignment and Image Stacking, this familiar arrangement gives the wavefront team an intuitive and natural way of visualizing changes in the segment spots in the context of the entire primary . We can now actually watch the slowly form into its precise, intended shape!”



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Webb team brings 18 dots of starlight into hexagonal formation (2022, February 19)
retrieved 20 February 2022
from https://phys.org/news/2022-02-webb-team-dots-starlight-hexagonal.html

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Hexbyte Glen Cove New study brings us one step closer to growing human organs for transplantation

Hexbyte Glen Cove

Credit: CC0 Public Domain

Realizing the vision of culturing organs for use in life-saving transplantation procedures is still a long way off. However, the work of Prof. Jacob Hanna on stem cells is paving the way for this to become a reality.

Hanna and his team from the Weizmann Institute of Science’s Molecular Genetics Department have found a way to culture human stem in a much earlier state than was previously possible. Not only that, the they created are far more competent, meaning that they are able to integrate more efficiently with their host environment. This substantially improves the chances of obtaining what is called a cross-species chimera—allowing cells from one creature to play a substantial role in the development of another.

The recently published findings demonstrate that very early human cells can be created and then successfully integrated into mice, owing to their undifferentiated (or “naïve”) state, wherein they can develop into any type of cell in the body, including other stem cells. Additionally, the researchers lay out a protocol for significantly increasing the efficiency (or competence) with which these cells can integrate. Improving our ability to create and study these cell types could be used in the future to transfer cells—if not organs—from one animal to another, humans included.

Hanna’s lab broke ground in 2013 when they were the first to inject human stem cells into mice and show that they can successfully integrate into the latter’s developing embryos. Eight years after this study was first published, Hanna and his team felt that they could go one step further by attempting to produce an even earlier, “fully” naïve form of stem cells for use in similar procedures. As they were mulling over the idea, Hanna knew that this might be nearly—if not altogether—impossible to achieve. “Our experience with producing similar cells in mice has taught us to expect challenging obstacles along the way,” says Hanna.

These cells normally suffer from genetic as well as epigenetic instability, and in the end they don’t differentiate too well, which is key to proper embryonic development and a prerequisite for their integration into another animal’s embryo. In fact, only about 1-3 percent of cells that have been transferred between species actually manage to integrate and contribute to development.

To boost these numbers, the researchers in the new study inhibited two additional signaling pathways to produce naïve human stem cells having a stable genome, relatively few gene regulation glitches, and most importantly, the ability to differentiate perfectly. The researchers also mutated an important gene that contributes to stability, which resulted in not only competent but also competitive stem cells that can integrate well without causing damage to the host. “We found a way to make human stem cells more competent, and competitive, increasing the chances for a successful transfer by about fivefold compared to what we were able to do in the past,” concludes Hanna.

While the previous study showed that human naïve stem cells can differentiate into primordial germ cells—the progenitors of egg or sperm cells—the fully naïve stem cells produced in the present study can also differentiate into extraembryonic tissues, the placenta and yolk sac cells that sustain the developing embryo. Such cells could be used, for example, as the source for developing synthetic embryos without the need for donor eggs. “Reaching this state with mouse stem cells is particularly difficult to accomplish,” Hanna explains, noting that “human cells are apparently different.”

This is perhaps the most surprising finding that the researchers made—highlighting the differences between the behavior of human and mouse stem cells, and between the different states of naïve cells. These differences expose the work that still needs to be done in making the dream of developing “made-to-order” organs a real-world actuality.

According to Hanna, understanding these differences will be pivotal for overcoming myriad issues still facing the field of stem cell research and application: “If in the future we should wish to grow a pancreas in pigs for human transplantation, for example, we will have to take into account these massive evolutionary differences between species, beginning with mice and humans.” For now, it would seem that Hanna and his team have taken a constructive leap in that direction.



More information:
Jonathan Bayerl et al, Principles of signaling pathway modulation for enhancing human naive pluripotency induction, Cell Stem Cell (2021). DOI: 10.1016/j.stem.2021.04.001

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Hexbyte Glen Cove Eta brings heavy rains, deadly mudslides to Honduras thumbnail

Hexbyte Glen Cove Eta brings heavy rains, deadly mudslides to Honduras

Hexbyte Glen Cove

A woman works to recover the part of roof damaged by Hurricane Eta in Wawa, Nicaragua, Tuesday, Nov. 3, 2020. Eta slammed into Nicaragua’s Caribbean coast with potentially devastating winds Tuesday, while heavy rains thrown off by the Category 4 storm already were causing rivers to overflow across Central America. (AP Photo/Carlos Herrera)

Eta moved into Honduras on Wednesday as a weakened tropical depression but still bringing the heavy rains that have drenched and caused deadly landslides in the country’s east and in northern Nicaragua.

The storm no longer carried the winds of the Category 4 hurricane that battered Nicaragua’s coast Tuesday, but it was moving so slowly and dumping so much rain that much of Central America was on high alert. Eta had sustained winds of 35 mph (55 kph) and was moving west-northwest at 7 mph (11 kph) Wednesday night. It was 115 miles (185 kilometers) south-southeast of La Ceiba.

The long-term forecast shows Eta taking a turn over Central America and then reforming as a in the Caribbean—possibly reaching Cuba on Sunday and southern Florida on Monday.

Heavy rain was forecast to continue across Honduras through at least Thursday as Eta moved northward toward the capital of Tegucigalpa and the northern city of San Pedro Sula.

Before the center of Eta had even reached Honduras, hundreds of people had been forced from their homes by floodwaters.

Early Tuesday, a 12-year-old girl died in a mudslide in San Pedro Sula, said Marvin Aparicio of Honduras’ emergency management agency.

On Wednesday afternoon, confirmation came from Honduras’ emergency management agency of the death of a 15-year-old boy in the central Honduras town of Sulaco. Mayor Edy Chacón said the boy drowned trying to cross a rain-swollen river. That brought the storm’s death toll to at least four in Nicaragua and Honduras.

A man walks his bike through knee-deep floodwaters in a neighborhood of Jehova, Honduras, Wednesday, Nov. 4, 2020. Eta weakened from the Category 4 hurricane to a tropical storm after lashing Nicaragua’s Caribbean coast for much of Tuesday, its floodwaters isolating already remote communities and setting off deadly landslides. (AP Photo/Delmer Martinez)

Aparicio said Wednesday that some 379 homes had been destroyed, mostly by floodwaters. There were 38 communities cut off by washed out roads and five bridges in the country were wiped out by swollen rivers.

Among those rescued from their flooded homes were Óscar Armando Martínez Flores, his wife and seven children. Their home near the Lancetilla river in northeast Honduras flooded. They made it out only with the clothes they were wearing.

“The rains began Monday and the river overflowed,” Martínez said Wednesday from a sports complex serving as a shelter in the city of Tela. “The firefighters and police arrived to take us out because the houses were flooded.”

Martínez was already in dire straits before the storm. A construction worker, he hadn’t been able to find work in eight months since the coronavirus pandemic began there. He has been selling tortillas to keep his family afloat.

A man walks through a flooded road in Okonwas, Nicaragua, Wednesday, Nov. 4, 2020. Eta weakened from the Category 4 hurricane to a tropical storm after lashing Nicaragua’s Caribbean coast for much of Tuesday, its floodwaters isolating already remote communities and setting off deadly landslides. (AP Photo/Carlos Herrera)

Francisco Argeñal chief of meteorology at Honduras’ Center for Atmospheric, Oceanographic and Seismic Studies, said he expected more of the country’s rivers to jump their banks.

The U.S. National Hurricane Center forecast that parts of Nicaragua and Honduras could receive 15 to 25 inches (380 to 635 millimeters) of rain, with 40 inches (1,000 millimeters) possible in some isolated parts.

Eta left a path of destruction across northern Nicaragua starting with the coastal city of Bilwi.

In Bilwi on Wednesday, civil defense brigades worked to clear streets of downed trees, power lines and sheets of metal roofing. Some neighborhoods were completely flooded. Vice President and first lady Rosario Murillo said more than 51,000 families remained without power in the affected areas.

“The debris teams are starting to work and we still can’t give a sense of what happened,” said Ivania Díaz, a local government official in Bilwi. “We have seen very humble homes completely destroyed.”

Residents wade through a flooded road carrying some belongings, in Progreso Yoro, Honduras, Wednesday, Nov. 4, 2020. Eta weakened from the Category 4 hurricane to a tropical storm after lashing the Caribbean coast for much of Tuesday, its floodwaters isolating already remote communities and setting off deadly landslides. (AP Photo/Delmer Martinez)

South of Bilwi, closer to where Eta came ashore Tuesday, the seaside Miskito community of Wawa Bar was devastated. The military had evacuated the community before Eta hit, but what residents found Wednesday was distressing. Wind-twisted trees, shredded roofs and some structures damaged beyond recognition sat within view of the sea.

“There’s nothing standing here,” an unidentified resident told a local television station. “Wawa Bar is now a Miskito community where destruction reigns.”

Inland there was flooding in Sarawas and the Prinzapolka river had risen more than 10 feet (3.7 meters) and threatened communities along its banks. “We are watching the Prinzapolka because there could be risk of an overflow,” Murillo said in a news conference Wednesday.

Murillo said the government was preparing a damage report that would be used to request international assistance.

A man walks through a flooded road with a ladder in San Manuel, Honduras, Wednesday, Nov. 4, 2020. Eta weakened from the Category 4 hurricane to a tropical storm after lashing the Caribbean coast for much of Tuesday, its floodwaters isolating already remote communities and setting off deadly landslides. (AP Photo/Delmer Martinez)

Nicaragua’s meteorology director Marcio Baca said the storm was saturating the north and Pacific coast of the country with heavy rain. He compared it to Hurricane Joan in 1988.

Two gold miners were killed in a landslide Tuesday in Bonanza, about 100 miles (160 kilometers) west of where Eta made landfall, said Lt. Cesar Malespin of the Bonanza Fire Department.

In the northern province of Jinotega, communities were already flooded. Floodwaters took down a suspension bridge over the Wamblan river and some 30 people were evacuated early Wednesday from Wiwili, according to local radio.

Northern Nicaragua is home to most of the country’s production of coffee, a critical export. Lila Sevilla, president of the National Alliance of Nicaraguan Coffee Producers, said they were concerned about landslides that could affect coffee plants and block roads needed to bring the harvest to market.

  • A man walks through a flooded road in Okonwas, Nicaragua, Wednesday, Nov. 4, 2020. Eta weakened from the Category 4 hurricane to a tropical storm after lashing Nicaragua’s Caribbean coast for much of Tuesday, its floodwaters isolating already remote communities and setting off deadly landslides. (AP Photo/Carlos Herrera)
  • A man standing on a bridge looks out at the Ulua River in Progreso Yoro, Honduras, Wednesday, Nov. 4, 2020. Eta weakened from the Category 4 hurricane to a tropical storm after lashing the Caribbean coast for much of Tuesday, its floodwaters isolating already remote communities and setting off deadly landslides. (AP Photo/Delmer Martinez)
  • A man fixes the roof of a home surrounded by floodwaters brought on by Hurricane Eta in Wawa, Nicaragua, Tuesday, Nov. 3, 2020. Eta slammed into Nicaragua’s Caribbean coast with potentially devastating winds Tuesday, while heavy rains thrown off by the Category 4 storm already were causing rivers to overflow across Central America. (AP Photo/Carlos Herrera)
  • A boy looks over at the the river inundated with flood waters brought on by Hurricane Eta in Wawa, Nicaragua, Tuesday, Nov. 3, 2020. Eta slammed into Nicaragua’s Caribbean coast with potentially devastating winds Tuesday, while heavy rains thrown off by the Category 4 storm already were causing rivers to overflow across Central America. (AP Photo/Carlos Herrera)
  • Residents stand outside a home surrounded by floodwaters brought on by Hurricane Eta in Wawa, Nicaragua, Tuesday, Nov. 3, 2020. Eta slammed into Nicaragua’s Caribbean coast with potentially devastating winds Tuesday, while heavy rains thrown off by the Category 4 storm already were causing rivers to overflow across Central America. (AP Photo/Carlos Herrera)
  • Residents stand outside a home surrounded by floodwaters brought on by Hurricane Eta in Wawa, Nicaragua, Tuesday, Nov. 3, 2020. Eta slammed into Nicaragua’s Caribbean coast with potentially devastating winds Tuesday, while heavy rains thrown off by the Category 4 storm already were causing rivers to overflow across Central America. (AP Photo/Carlos Herrera)
  • Residents ride out Hurricane Eta in a shelter in the Nazareth community of El Naranjal, Nicaragua, Tuesday, Nov. 3, 2020. Eta weakened from the Category 4 hurricane to a tropical storm after lashing Nicaragua’s Caribbean coast for much of Tuesday, its floodwaters isolating already remote communities and setting off deadly landslides. (AP Photo/Carlos Herrera)
  • People rest in a makeshift shelter after Hurricane Eta made landfall, in Wawa, Nicaragua, Tuesday, Nov. 3, 2020. Eta slammed into Nicaragua’s Caribbean coast with potentially devastating winds Tuesday, while heavy rains thrown off by the Category 4 storm already were causing rivers to overflow across Central America. (AP Photo/Carlos Herrera)
  • People arrive in a boat to Wawa in Wawa, Nicaragua, Tuesday, Nov. 3, 2020. Hurricane Eta slammed into Nicaragua’s Caribbean coast with potentially devastating winds Tuesday, while heavy rains thrown off by the Category 4 storm already were causing rivers to overflow across Central America. (AP Photo/Carlos Herrera)
  • Angel Zavala, 72, carries a few belongings he was able to salvage from his home in a flooded neighborhood of Jehova, Honduras, Wednesday, Nov. 4, 2020. Eta weakened from the Category 4 hurricane to a tropical storm after lashing the Caribbean coast for much of Tuesday, its floodwaters isolating already remote communities and setting off deadly landslides. (AP Photo/Delmer Martinez)
  • A residents repairs a gate while standing in knee-deep floodwaters outside his home in Jehova, Honduras, Wednesday, Nov. 4, 2020. Eta weakened from the Category 4 hurricane to a tropical storm after lashing the Caribbean coast for much of Tuesday, its floodwaters isolating already remote communities and setting off deadly landslides. (AP Photo/Delmer Martinez)

“It’s still early to evaluate the impact of the rain, but we can expect damage to the road network in the northern towns,” Sevilla said. The harvest hadn’t started yet, but extended rain could cause the coffee to mature too quickly and affect its quality, she said.

In the Pacific, Tropical Storm Odalys continued to move across the open ocean and posed no threat to land.



© 2020 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed without permission.

Citation:
Eta brings heavy rains, deadly mudslides to Honduras (2020, November 5)
retrieved 5 November 2020
from https://phys.org/news/2020-11-eta-heavy-deadly-mudslides-honduras.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.