In today’s Bulldog wrapup of science and technology news:

  • Massachusetts Uber, Lyft screenings called toughest in US
  • Great Barrier Reef sees record coral deaths this year
  • Sen. Warren blasts drug approval bill as ‘extortion’
  • San Francisco’s public railway system hit by hackers

The details:

  • Massachusetts Uber, Lyft screenings called toughest in US

Drivers for ride-hailing companies Uber and Lyft will undergo what state officials call the most comprehensive background checks in the U.S. under agreements announced Monday by Gov. Charlie Baker’s administration.

The screenings will begin on Jan. 6, with both companies guaranteeing that every driver on the road will have passed a thorough state criminal background check by April 3, according to the separately negotiated deals.

The new Massachusetts protocols establish a “national standard” for screening those who drive for the ride-hailing firms, Baker said.

  • Great Barrier Reef sees record coral deaths this year

Warming oceans this year have caused the largest die-off of corals ever recorded on Australia’s Great Barrier Reef, scientists said Tuesday.

The worst-affected area is a 700-kilometer (400-mile) swath in the north of the World Heritage-listed 2,300-kilometer (1,400-mile) chain of reefs off Australia’s northeast coast, said the Australian Research Council Centre of Excellence for Coral Reef Studies.

The center, based at James Cook University in Queensland state, found during dive surveys in October and November that the swath north of Port Douglas had lost an average of 67 percent of its shallow-water corals in the past nine months.

Farther south, over the vast central and southern regions that cover most of the reef, scientists found a much lower death toll.

The central region lost 6 percent of bleached coral and the southern region only 1 percent.

“The mortality we’ve measured along the length of the Great Barrier Reef is incredibly patchy,” the center’s director, Terry Hughes, told reporters. “There’s very severe damage in the northern section of the reef.”

“The good news is that south of Port Douglas, including the major tourist areas around Cairns and the Whitsundays (Whitsunday Islands), have had relatively low levels of mortality,” he added.

  • Sen. Warren blasts drug approval bill as ‘extortion’

Sen. Elizabeth Warren has delivered a ferocious attack on congressional Republicans and Senate Majority Leader Mitch McConnell over a medical research bill, putting fellow Democrats on the spot by pushing them to oppose a measure she said “is corrupt, and it is very, very dangerous.”

As Congress began the final stretch of its post-election session, Warren said the 996-page measure — a top priority for GOP leaders and backed by the biomedical industry — was riddled with provisions that she called “a bunch of special giveaways” to big pharmaceutical companies.

“They didn’t send us here to whimper, whine or grovel,” she said on the Senate floor about Democrats, using the populist rhetoric that has given her one of her party’s highest profiles. “They sent us here to say no to efforts to sell Congress to the highest bidder.”

All but taunting her own party, Warren, D-Mass., said, “Republicans will control this government, but they cannot hand that control over to big corporations unless Democrats roll over and allow them to do so.”

  • San Francisco’s public railway system hit by hackers

Some passengers on San Francisco’s public railway enjoyed free rides during part of the Thanksgiving holiday weekend after hackers infiltrated hundreds of its workers’ computers and email accounts.

The San Francisco Municipal Transportation Agency says it decided to open the gates at underground stations of its light rail system Friday and Saturday after detecting a “ransomware” attack aimed at stealing sensitive information in an attempt to be paid for the data’s return. Regular fares were still charged for bus rides.

Agency spokesman Paul Rose says an investigation determined that the hackers didn’t get any financial records or other potentially damaging information about the system’s customers or employees.

As of late Monday afternoon, the agency was still trying to determine how much revenue it lost while giving free rides.