London open: Stocks rise on stimulus hopes; Barclays in focus

- US, UK, China and ECB stimulus hopes drive gains- Barclays hits headlines after CEO departs- Miners rise as metals prices advance Hopes that central banks will inject more stimulus into the global economy were boosting UK stocks on Tuesday morning.Yesterday's disappointing manufacturing data in the US has prompted calls for the Federal Reserve to begin fresh stimulus into the world's largest economy. The ISM reported that the manufacturing sector contracted for the first time since July 2009. According to BNP Paribas, weak employment figures later this week may add to pressure on the Fed.There are also calls for China to cut its reserve requirement ratio (RRR) for its banks in an effort to boost liquidity. The China Securities Journal said that the RRR, currently at 20%, should be reduced again to lower the chance of a liquidity crunch next month.Meanwhile, investors will be looking ahead to policy decisions by the European Central Bank (ECB) and the Bank of England (BoE) on Thursday. The ECB is widely expected to cut interest rates to a new record-low, while the BoE is predicted to ramp up its asset purchase programme.Bob Diamond resigns as Barclays CEOMaking headlines this morning was the news that Bob Diamond has called its quits at Barclays, bowing in to political pressure following last week's news that the bank was involved in Libor manipulation. Marcus Agius, who said yesterday that he would resign as Chairman, is to become a full-time Chairman while the board searches for a new CEO. Shares advanced after this morning's announcement. Mining stocks were tracking metals prices higher early on. Vedanta, Rio Tinto, Kazakhmys, Fresnillo, ENRC and BHP Billiton were all making gains in spite of Deutsche Bank cutting target prices across the sector.FTSE 250 resource group Talvivaara Mining was bucking the trend after saying that it is unlikely to hit its nickel production targets this year as a result of flooding, scheduled maintenance and a fatality-related stoppage during its second quarter. Shares dropped 15%.House builder Persimmon edged higher after saying it had a good first half of the year with sales rates and prices running ahead of the corresponding period of 2011.Oil explorer Salamander Energy fell after saying that test results at its dig in the Gulf of Thailand are "conclusive", with analysis showing that water is present in the tested section; in other words the Far East-1 well cannot be used for production.Elsewhere, AIM-listed TV group Motive Television surged 16% after taking full control of its intellectual property rights by buying out the minority shareholder in its Spanish subsidiary.FTSE 100 - RisersVedanta Resources (VED) 947.00p +4.53%Kazakhmys (KAZ) 748.50p +2.53%Rio Tinto (RIO) 3,125.00p +2.11%Aviva (AV.) 288.40p +2.02%Meggitt (MGGT) 395.50p +1.85%Antofagasta (ANTO) 1,116.00p +1.73%Fresnillo (FRES) 1,514.00p +1.61%AstraZeneca (AZN) 2,928.00p +1.60%Petrofac Ltd. (PFC) 1,459.00p +1.53%Standard Chartered (STAN) 1,437.00p +1.27%FTSE 100 - FallersAberdeen Asset Management (ADN) 258.00p -2.53%Royal Bank of Scotland Group (RBS) 216.10p -1.32%United Utilities Group (UU.) 671.50p -1.18%Severn Trent (SVT) 1,643.00p -1.14%BP (BP.) 428.25p -0.98%ITV (ITV) 77.15p -0.84%Centrica (CNA) 317.20p -0.75%Kingfisher (KGF) 287.00p -0.69%Capital Shopping Centres Group (CSCG) 319.30p -0.59%Diageo (DGE) 1,649.00p -0.54%FTSE 250 - RisersCentamin (DI) (CEY) 74.50p +5.23%Ocado Group (OCDO) 78.60p +4.80%Bumi (BUMI) 320.00p +3.23%Rank Group (RNK) 121.00p +2.63%Aquarius Platinum Ltd. (AQP) 49.24p +2.33%EnQuest (ENQ) 112.60p +2.27%Redrow (RDW) 128.50p +2.07%Wood Group (John) (WG.) 714.50p +1.85%Regus (RGU) 92.25p +1.77%African Barrick Gold (ABG) 400.10p +1.75%FTSE 250 - FallersTalvivaara Mining Company (TALV) 144.00p -15.29%JD Sports Fashion (JD.) 691.00p -4.56%Chemring Group (CHG) 265.30p -3.21%Salamander Energy (SMDR) 166.80p -2.80%Renishaw (RSW) 1,366.00p -2.01%Hansteen Holdings (HSTN) 72.55p -1.96%Man Group (EMG) 73.10p -1.81%New World Resources A Shares (NWR) 328.30p -1.79%Yule Catto & Co (YULC) 141.20p -1.53%Perform Group (PER) 399.60p -1.31%BC