Sanders supporters reject call for unity as DNC begins Bernie Sanders, Elizabeth Warren and Michelle Obama urge support for Hillary Clinton; Trump gets a big poll bump; 'Isis terrorists' take hostages in France A man wears a Bernie Sanders jacket during day one of the Democratic national convention at the Wells Fargo Center in Philadelphia Monday. Photograph: Brendan Smialowski/AFP/Getty Images Edward Helmore in New York Democrats recalibrate with Michelle, Bernie and Liz Democrats sought to regain control of their party's convention in Philadelphia on Monday, with impassioned pleas for unity by Senator Bernie Sanders of Vermont, Senator Elizabeth Warren of Massachusetts and first lady Michelle Obama, who urged supporters to endorse presumptive nominee Hillary Clinton."Any objective observer will conclude that – based on her ideas and her leadership – Hillary Clinton must become the next president of the United States," Sanders said. Democratic convention: passionate end to day one steadies early drama Despite a direct plea for calm from Sanders, many of his 1,846 delegates repeatedly jeered at mention of his erstwhile rival's name. Members of Bernie's army said they were unconvinced by what they heard and called on Clinton to make firm commitments to Sanders' radical agenda – or his endorsement of Hillary Clinton. "It's not what a lot of us wanted to hear," said 22-year-old Sarah Hernandez, "We wanted to hear him lay down the law, saying: 'This election was rigged from the start,' and how if you compare the polls of him versus Trump compared to Hillary against Trump, he wins." 'He convinced none of us': Bernie Sanders diehards react to convention speech Trump's bump considered significant Republican presidential nominee Donald Trump has risen 3.5 points in national polling averages in the past week – a significant jump given that he's no ordinary presidential nominee, writes Guardian US data editor Mona Chalabi. All four polls found that Trump was leading over Clinton. Together, they were enough to shift the average in Trump's favor. Why Trump's bump in the polls is more significant than ever Normandy church siege resolved A priest and two hostage-takers are dead after a siege that began when two men armed with knives took hostages in a church in Saint-Étienne-du-Rouvray, near Rouen. French media reported that five hostages had been held, including a priest, two nuns and two worshippers, and that a sixth escaped and raised the alarm. President Francois Hollande said the incident was a terrorist attack, carried out by "two terrorists who claimed to be from Isis". Hostage among three dead in Normandy church siege, say French police Japan knife attack A man who claimed he wanted to kill disabled people left at least 19 dead and 26 others injured after a knife attack at a care facility in Japan. The suspect, named Satoshi Uematsu, told police in Sagamihara, outside Tokyo, "it is better that disabled people disappear". Emergency workers said at least 20 of the wounded had sustained serious injuries, according to the Kyodo news agency. Japan knife attack: stabbing at care centre leaves 19 dead New map of the universe points to mysterious 'dark energy' The largest ever 3D map of the universe strengthens astronomers' belief that three quarters of the cosmos is made up of "dark matter". The map was made by the Sloan Digital Sky Survey in New Mexico, in tandem with the Irénée du Pont Telescope at Las Campanas Observatory, Chile. We may live in a Universe where only 2% of it is the familiar atoms that make up humans, stars and planets, but we still cant find the other 98% ... Largest ever map of the universe points to mysterious 'dark energy' Harry Potter, staged After weeks of secrecy, the reviews are finally out for the Harry Potter stage adaptation. Harry Potter and the Cursed Child at the Palace Theatre in London, is a "thrilling theatrical spectacle", writes Michael Billington, "that will make much more sense to hardened Potterheads than to anyone who is not a member of the global cult". Harry Potter and the Cursed Child review – duel of dark and light carried off with dazzling assurance Panama canal too small? A third ship has been damaged after hitting the new Panama Canal wall in the third incident since the expanded waterway opened one month ago. A photograph published by the maritime online news site gCaptain.com showed the vessel with a sizeable gash in its hull. The newly expanded $5.4bn canal channel was inaugurated on 26 June. Ship hits new Panama Canal wall, sparking design concerns The power of nudity Sistine Chapel buttocks are veiled; Leonardo da Vinci's Leda and the Swan, one of the first openly carnal depictions of myth in art, was probably destroyed deliberately by its French owner. These are far from the only incidents where Renaissance art has been considered so sensual and provocative they must be suppressed. As a new exhibition readies to show Adam and Eve uncovered, Jonathan Jones considers how nudity still has power to shock. The great art cover-up: Renaissance nudity still has power to shock Marissa Mayer's clouded future For the past four years, Marissa Mayer has led the troubled internet giant but her efforts to turn Yahoo around culminated with a $4.4bn loss reported earlier this year and the sale of Yahoo's US business to Verizon for $5bn. Mayer has said she plans to stay on, though she could walk away with around $219m. "I love Yahoo, and I believe in all of you. It's important to me to see Yahoo into its next chapter." After trying to position Yahoo as a media company, is this likely? What's the future for Yahoo CEO Marissa Mayer? In case you missed it… The DNC Wikileaks email leak has revealed that pop star Ariana Grande was dropped from a White House gala last September, after the Disney star was caught on video licking other people's donuts and saying "I hate America" – an act of subversion that cost her the gig. DNC finance chair Zachary Allen said he was concerned that #donutgate would seem to endorse an impression of double standards. Ariana Grande's donut-licking incident cost her a gig at the White House Manage your emails | Unsubscribe | Trouble viewing? You are receiving this email because you are a subscriber to Guardian US Briefing. Guardian News & Media Limited - a member of Guardian Media Group PLC. Registered Office: 222 Broadway, 22nd and 23rd Floors, New York, New York, 10038