Extinctions Heal Slowly

first_imgThe history of life on Earth has been a heated tug of war between forces that power the birth of new species and those that grind life forms into oblivion. Now a new study suggests that while extinction rates vary widely, origination rates march to their own slow drummer. The study, published in the 3 January issue of Nature, fuels fears that it will take millions of years for biological diversity to recover from the current wave of human-caused extinctions.In recent years scientists have challenged a long-held assumption that evolution’s pace can accelerate to fill the biological holes caused by episodic mass extinctions. Last year, a pair of researchers reported that it takes about 10 million years for evolution to renew the planet’s biodiversity following an extinction event, whether that event is large or small. Building on that finding, one team member, earth scientist James Kirchner at the University of California, Berkeley, decided to compare rates of extinction to rates of origination over a 500-million-year period.To compare evolutionary clocks, Kirchner turned to the same database he’d analyzed earlier: the late Jack Sepkoski’s encyclopedic compilation of marine animal fossils, which spans a 540-million-year history and lists the first and last known occurrences of about 4500 families and 36,000 genera. To untangle such a massive and uneven database, Kirchner used a specialized form of a mathematical technique called spectral analysis, which was developed by astrophysicists to make sense of the complex light signals received from distant stars. Kirchner concluded that extinction rates are up to two and a half times more variable than origination rates, with originations of new species pulling ahead of extinctions only when researchers look at chunks of time greater than 25 million years. The finding is further proof that “while extinction rates can spike, diversification rates can’t rev up to offset them,” Kirchner says.Sign up for our daily newsletterGet more great content like this delivered right to you!Country *AfghanistanAland IslandsAlbaniaAlgeriaAndorraAngolaAnguillaAntarcticaAntigua and BarbudaArgentinaArmeniaArubaAustraliaAustriaAzerbaijanBahamasBahrainBangladeshBarbadosBelarusBelgiumBelizeBeninBermudaBhutanBolivia, Plurinational State ofBonaire, Sint Eustatius and SabaBosnia and HerzegovinaBotswanaBouvet IslandBrazilBritish Indian Ocean TerritoryBrunei DarussalamBulgariaBurkina FasoBurundiCambodiaCameroonCanadaCape VerdeCayman IslandsCentral African RepublicChadChileChinaChristmas IslandCocos (Keeling) IslandsColombiaComorosCongoCongo, The Democratic Republic of theCook IslandsCosta RicaCote D’IvoireCroatiaCubaCuraçaoCyprusCzech RepublicDenmarkDjiboutiDominicaDominican RepublicEcuadorEgyptEl SalvadorEquatorial GuineaEritreaEstoniaEthiopiaFalkland Islands (Malvinas)Faroe IslandsFijiFinlandFranceFrench GuianaFrench PolynesiaFrench Southern TerritoriesGabonGambiaGeorgiaGermanyGhanaGibraltarGreeceGreenlandGrenadaGuadeloupeGuatemalaGuernseyGuineaGuinea-BissauGuyanaHaitiHeard Island and Mcdonald IslandsHoly See (Vatican City State)HondurasHong KongHungaryIcelandIndiaIndonesiaIran, Islamic Republic ofIraqIrelandIsle of ManIsraelItalyJamaicaJapanJerseyJordanKazakhstanKenyaKiribatiKorea, Democratic People’s Republic ofKorea, Republic ofKuwaitKyrgyzstanLao People’s Democratic RepublicLatviaLebanonLesothoLiberiaLibyan Arab JamahiriyaLiechtensteinLithuaniaLuxembourgMacaoMacedonia, The Former Yugoslav Republic ofMadagascarMalawiMalaysiaMaldivesMaliMaltaMartiniqueMauritaniaMauritiusMayotteMexicoMoldova, Republic ofMonacoMongoliaMontenegroMontserratMoroccoMozambiqueMyanmarNamibiaNauruNepalNetherlandsNew CaledoniaNew ZealandNicaraguaNigerNigeriaNiueNorfolk IslandNorwayOmanPakistanPalestinianPanamaPapua New GuineaParaguayPeruPhilippinesPitcairnPolandPortugalQatarReunionRomaniaRussian FederationRWANDASaint Barthélemy Saint Helena, Ascension and Tristan da CunhaSaint Kitts and NevisSaint LuciaSaint Martin (French part)Saint Pierre and MiquelonSaint Vincent and the GrenadinesSamoaSan MarinoSao Tome and PrincipeSaudi ArabiaSenegalSerbiaSeychellesSierra LeoneSingaporeSint Maarten (Dutch part)SlovakiaSloveniaSolomon IslandsSomaliaSouth AfricaSouth Georgia and the South Sandwich IslandsSouth SudanSpainSri LankaSudanSurinameSvalbard and Jan MayenSwazilandSwedenSwitzerlandSyrian Arab RepublicTaiwanTajikistanTanzania, United Republic ofThailandTimor-LesteTogoTokelauTongaTrinidad and TobagoTunisiaTurkeyTurkmenistanTurks and Caicos IslandsTuvaluUgandaUkraineUnited Arab EmiratesUnited KingdomUnited StatesUruguayUzbekistanVanuatuVenezuela, Bolivarian Republic ofVietnamVirgin Islands, BritishWallis and FutunaWestern SaharaYemenZambiaZimbabweI also wish to receive emails from AAAS/Science and Science advertisers, including information on products, services and special offers which may include but are not limited to news, careers information & upcoming events.Required fields are included by an asterisk(*)The work supports the emerging view that “origination and extinction are decidedly different processes determined by different rules,” says Arnold I. Miller, a paleobiologist at the University of Cincinnati in Ohio. But Douglas Erwin, a paleobiologist at the Smithsonian’s National Museum of Natural History in Washington, D.C., says he’s “leery about the analytical structure of the study,” because it’s based on an outdated version of the time scale that accompanies Sepkoski’s database. “I’m not sure that the analysis is sufficiently robust to support the conclusions,” says Erwin.Related sites Last year’s paper by Kirchner and a colleague, showing it takes 10 million years for biodiversity to be renewed following an extinction event Commentary by Douglas Erwin on that paper Milwaukee Public Museum’s Geologic Time Scale Diversity Through Time graphic based on Sepkoski’s workCycles of mass and minor extinctions on Earth, from the Hooper Virtual Paleontological Museumlast_img read more

Cairo or Bust for Nefertiti

first_imgPhoto by Philip Pikart; Neues Museum, Berlin She has been dead for more than 3 millennia, but Queen Nefertiti is kicking up diplomatic dust between Cairo and Berlin. Today, Egypt’s Supreme Council of Antiquities demanded the return of a famous bust of the queen which has been in Berlin since its discovery in 1912 by German archaeologists. Egypt has been trying to get her back since the 1920s—Adolf Hitler refused to send her back in the 1930s—but now it is bringing more pressure to bear. Council chief Zahi Hawass made the request in writing to the Prussian Cultural Heritage Foundation which oversees the Neues Museum where Nefertiti now reigns. Hawass said in a statement that the council is asking that “this unique treasure be returned to the possession of its rightful owners.” Egypt maintains the discoverer misled Egyptian authorities after its discovery. But the initial German reaction was dismissive. A foundation statement (German, here) noted that the bust was removed with permission by the Egyptian government. “There can be not talk of anyone being fooled,” the statement read. A German foreign ministry spokesperson noted at a press briefing today in Berlin that the council request is not a formal government request, since it was addressed to the foundation, and since it was not signed by the Egyptian prime minister or foreign minister. The 3300-year-old limestone bust, which still boasts vibrant colors, has become an icon of female beauty and power and reflects the unique style of the Amarna period. Nefertiti was wife of Akhenaten, the pharaoh who abandoned the old gods during his New Kingdom reign, and he spurred a radical new style in Egyptian art as well as religion. For now, it seems Nefertiti will stay in Berlin. Sign up for our daily newsletterGet more great content like this delivered right to you!Country *AfghanistanAland IslandsAlbaniaAlgeriaAndorraAngolaAnguillaAntarcticaAntigua and BarbudaArgentinaArmeniaArubaAustraliaAustriaAzerbaijanBahamasBahrainBangladeshBarbadosBelarusBelgiumBelizeBeninBermudaBhutanBolivia, Plurinational State ofBonaire, Sint Eustatius and SabaBosnia and HerzegovinaBotswanaBouvet IslandBrazilBritish Indian Ocean TerritoryBrunei DarussalamBulgariaBurkina FasoBurundiCambodiaCameroonCanadaCape VerdeCayman IslandsCentral African RepublicChadChileChinaChristmas IslandCocos (Keeling) IslandsColombiaComorosCongoCongo, The Democratic Republic of theCook IslandsCosta RicaCote D’IvoireCroatiaCubaCuraçaoCyprusCzech RepublicDenmarkDjiboutiDominicaDominican RepublicEcuadorEgyptEl SalvadorEquatorial GuineaEritreaEstoniaEthiopiaFalkland Islands (Malvinas)Faroe IslandsFijiFinlandFranceFrench GuianaFrench PolynesiaFrench Southern TerritoriesGabonGambiaGeorgiaGermanyGhanaGibraltarGreeceGreenlandGrenadaGuadeloupeGuatemalaGuernseyGuineaGuinea-BissauGuyanaHaitiHeard Island and Mcdonald IslandsHoly See (Vatican City State)HondurasHong KongHungaryIcelandIndiaIndonesiaIran, Islamic Republic ofIraqIrelandIsle of ManIsraelItalyJamaicaJapanJerseyJordanKazakhstanKenyaKiribatiKorea, Democratic People’s Republic ofKorea, Republic ofKuwaitKyrgyzstanLao People’s Democratic RepublicLatviaLebanonLesothoLiberiaLibyan Arab JamahiriyaLiechtensteinLithuaniaLuxembourgMacaoMacedonia, The Former Yugoslav Republic ofMadagascarMalawiMalaysiaMaldivesMaliMaltaMartiniqueMauritaniaMauritiusMayotteMexicoMoldova, Republic ofMonacoMongoliaMontenegroMontserratMoroccoMozambiqueMyanmarNamibiaNauruNepalNetherlandsNew CaledoniaNew ZealandNicaraguaNigerNigeriaNiueNorfolk IslandNorwayOmanPakistanPalestinianPanamaPapua New GuineaParaguayPeruPhilippinesPitcairnPolandPortugalQatarReunionRomaniaRussian FederationRWANDASaint Barthélemy Saint Helena, Ascension and Tristan da CunhaSaint Kitts and NevisSaint LuciaSaint Martin (French part)Saint Pierre and MiquelonSaint Vincent and the GrenadinesSamoaSan MarinoSao Tome and PrincipeSaudi ArabiaSenegalSerbiaSeychellesSierra LeoneSingaporeSint Maarten (Dutch part)SlovakiaSloveniaSolomon IslandsSomaliaSouth AfricaSouth Georgia and the South Sandwich IslandsSouth SudanSpainSri LankaSudanSurinameSvalbard and Jan MayenSwazilandSwedenSwitzerlandSyrian Arab RepublicTaiwanTajikistanTanzania, United Republic ofThailandTimor-LesteTogoTokelauTongaTrinidad and TobagoTunisiaTurkeyTurkmenistanTurks and Caicos IslandsTuvaluUgandaUkraineUnited Arab EmiratesUnited KingdomUnited StatesUruguayUzbekistanVanuatuVenezuela, Bolivarian Republic ofVietnamVirgin Islands, BritishWallis and FutunaWestern SaharaYemenZambiaZimbabweI also wish to receive emails from AAAS/Science and Science advertisers, including information on products, services and special offers which may include but are not limited to news, careers information & upcoming events.Required fields are included by an asterisk(*)last_img read more

Texas Medical Board Approves Rules for Controversial Treatment

first_imgLast week, the Texas Medical Board signed off on what’s said to be the first state-level policy imposing oversight on experimental treatments using adult stem cells. The scientific community has mixed views on whether this is a good way to raise standards. Some experts say the rule will allow unscrupulous doctors to avoid U.S. Food and Drug Administration reviews. But others say it’s a good-faith effort to bring oversight to controversial treatments that clinics around the world offer for diseases including arthritis and multiple sclerosis. Read the Full Text Sign up for our daily newsletterGet more great content like this delivered right to you!Country *AfghanistanAland IslandsAlbaniaAlgeriaAndorraAngolaAnguillaAntarcticaAntigua and BarbudaArgentinaArmeniaArubaAustraliaAustriaAzerbaijanBahamasBahrainBangladeshBarbadosBelarusBelgiumBelizeBeninBermudaBhutanBolivia, Plurinational State ofBonaire, Sint Eustatius and SabaBosnia and HerzegovinaBotswanaBouvet IslandBrazilBritish Indian Ocean TerritoryBrunei DarussalamBulgariaBurkina FasoBurundiCambodiaCameroonCanadaCape VerdeCayman IslandsCentral African RepublicChadChileChinaChristmas IslandCocos (Keeling) IslandsColombiaComorosCongoCongo, The Democratic Republic of theCook IslandsCosta RicaCote D’IvoireCroatiaCubaCuraçaoCyprusCzech RepublicDenmarkDjiboutiDominicaDominican RepublicEcuadorEgyptEl SalvadorEquatorial GuineaEritreaEstoniaEthiopiaFalkland Islands (Malvinas)Faroe IslandsFijiFinlandFranceFrench GuianaFrench PolynesiaFrench Southern TerritoriesGabonGambiaGeorgiaGermanyGhanaGibraltarGreeceGreenlandGrenadaGuadeloupeGuatemalaGuernseyGuineaGuinea-BissauGuyanaHaitiHeard Island and Mcdonald IslandsHoly See (Vatican City State)HondurasHong KongHungaryIcelandIndiaIndonesiaIran, Islamic Republic ofIraqIrelandIsle of ManIsraelItalyJamaicaJapanJerseyJordanKazakhstanKenyaKiribatiKorea, Democratic People’s Republic ofKorea, Republic ofKuwaitKyrgyzstanLao People’s Democratic RepublicLatviaLebanonLesothoLiberiaLibyan Arab JamahiriyaLiechtensteinLithuaniaLuxembourgMacaoMacedonia, The Former Yugoslav Republic ofMadagascarMalawiMalaysiaMaldivesMaliMaltaMartiniqueMauritaniaMauritiusMayotteMexicoMoldova, Republic ofMonacoMongoliaMontenegroMontserratMoroccoMozambiqueMyanmarNamibiaNauruNepalNetherlandsNew CaledoniaNew ZealandNicaraguaNigerNigeriaNiueNorfolk IslandNorwayOmanPakistanPalestinianPanamaPapua New GuineaParaguayPeruPhilippinesPitcairnPolandPortugalQatarReunionRomaniaRussian FederationRWANDASaint Barthélemy Saint Helena, Ascension and Tristan da CunhaSaint Kitts and NevisSaint LuciaSaint Martin (French part)Saint Pierre and MiquelonSaint Vincent and the GrenadinesSamoaSan MarinoSao Tome and PrincipeSaudi ArabiaSenegalSerbiaSeychellesSierra LeoneSingaporeSint Maarten (Dutch part)SlovakiaSloveniaSolomon IslandsSomaliaSouth AfricaSouth Georgia and the South Sandwich IslandsSouth SudanSpainSri LankaSudanSurinameSvalbard and Jan MayenSwazilandSwedenSwitzerlandSyrian Arab RepublicTaiwanTajikistanTanzania, United Republic ofThailandTimor-LesteTogoTokelauTongaTrinidad and TobagoTunisiaTurkeyTurkmenistanTurks and Caicos IslandsTuvaluUgandaUkraineUnited Arab EmiratesUnited KingdomUnited StatesUruguayUzbekistanVanuatuVenezuela, Bolivarian Republic ofVietnamVirgin Islands, BritishWallis and FutunaWestern SaharaYemenZambiaZimbabweI also wish to receive emails from AAAS/Science and Science advertisers, including information on products, services and special offers which may include but are not limited to news, careers information & upcoming events.Required fields are included by an asterisk(*)last_img read more

Senate Panel Approves $100 Million Boost for NIH in 2013

first_imgThe Senate Appropriations Committee yesterday approved a modest $100 million raise for the National Institutes of Health (NIH) in the 2013 fiscal year which begins on 1 October. The 0.3% bump to a total of $30.723 billion is slightly better than the president’s request for no increase, but it is disappointing to the research community. The bill funding NIH provides $40 million for the Cures Acceleration Network, four times its current budget (but $10 million below the president’s request). But it rejects a proposal by the president to cut $50 million from the Institutional Development Award (IDeA) program, which seeks to give institutions in poorer states a better shot at NIH funding. Instead, the committee would maintain funding at about $276 million. “The Committee believes the IDeA program has made a significant contribution to biomedical research and creating a skilled workforce,” it notes in a report accompanying the bill. It also urges NIH to expand the number of schools eligible for the program. The committee did back a requested $28 million trim, to $165 million, for the National Children’s Study (NCS), an ambitious but troubled federal plan to follow the health of 100,000 children from before birth to age 21. The panel hopes the 15% cut “represents a positive sign that NIH intends to bring the costs of the NCS under control and spend its appropriation more efficiently,” it writes in the report. “The Committee is troubled that after appropriating nearly [$1 billion] for the NCS since the first work on it began in fiscal year 2000, only a few thousand children have been enrolled and fundamental questions about the project’s implementation still remain, particularly regarding the methods that will be used to recruit participants.” The panel also wants the National Academy of Sciences to review NCS’s statistical sampling strategy and for NIH to “improve its level of communication with the research community about any future changes to the project.” Sign up for our daily newsletterGet more great content like this delivered right to you!Country *AfghanistanAland IslandsAlbaniaAlgeriaAndorraAngolaAnguillaAntarcticaAntigua and BarbudaArgentinaArmeniaArubaAustraliaAustriaAzerbaijanBahamasBahrainBangladeshBarbadosBelarusBelgiumBelizeBeninBermudaBhutanBolivia, Plurinational State ofBonaire, Sint Eustatius and SabaBosnia and HerzegovinaBotswanaBouvet IslandBrazilBritish Indian Ocean TerritoryBrunei DarussalamBulgariaBurkina FasoBurundiCambodiaCameroonCanadaCape VerdeCayman IslandsCentral African RepublicChadChileChinaChristmas IslandCocos (Keeling) IslandsColombiaComorosCongoCongo, The Democratic Republic of theCook IslandsCosta RicaCote D’IvoireCroatiaCubaCuraçaoCyprusCzech RepublicDenmarkDjiboutiDominicaDominican RepublicEcuadorEgyptEl SalvadorEquatorial GuineaEritreaEstoniaEthiopiaFalkland Islands (Malvinas)Faroe IslandsFijiFinlandFranceFrench GuianaFrench PolynesiaFrench Southern TerritoriesGabonGambiaGeorgiaGermanyGhanaGibraltarGreeceGreenlandGrenadaGuadeloupeGuatemalaGuernseyGuineaGuinea-BissauGuyanaHaitiHeard Island and Mcdonald IslandsHoly See (Vatican City State)HondurasHong KongHungaryIcelandIndiaIndonesiaIran, Islamic Republic ofIraqIrelandIsle of ManIsraelItalyJamaicaJapanJerseyJordanKazakhstanKenyaKiribatiKorea, Democratic People’s Republic ofKorea, Republic ofKuwaitKyrgyzstanLao People’s Democratic RepublicLatviaLebanonLesothoLiberiaLibyan Arab JamahiriyaLiechtensteinLithuaniaLuxembourgMacaoMacedonia, The Former Yugoslav Republic ofMadagascarMalawiMalaysiaMaldivesMaliMaltaMartiniqueMauritaniaMauritiusMayotteMexicoMoldova, Republic ofMonacoMongoliaMontenegroMontserratMoroccoMozambiqueMyanmarNamibiaNauruNepalNetherlandsNew CaledoniaNew ZealandNicaraguaNigerNigeriaNiueNorfolk IslandNorwayOmanPakistanPalestinianPanamaPapua New GuineaParaguayPeruPhilippinesPitcairnPolandPortugalQatarReunionRomaniaRussian FederationRWANDASaint Barthélemy Saint Helena, Ascension and Tristan da CunhaSaint Kitts and NevisSaint LuciaSaint Martin (French part)Saint Pierre and MiquelonSaint Vincent and the GrenadinesSamoaSan MarinoSao Tome and PrincipeSaudi ArabiaSenegalSerbiaSeychellesSierra LeoneSingaporeSint Maarten (Dutch part)SlovakiaSloveniaSolomon IslandsSomaliaSouth AfricaSouth Georgia and the South Sandwich IslandsSouth SudanSpainSri LankaSudanSurinameSvalbard and Jan MayenSwazilandSwedenSwitzerlandSyrian Arab RepublicTaiwanTajikistanTanzania, United Republic ofThailandTimor-LesteTogoTokelauTongaTrinidad and TobagoTunisiaTurkeyTurkmenistanTurks and Caicos IslandsTuvaluUgandaUkraineUnited Arab EmiratesUnited KingdomUnited StatesUruguayUzbekistanVanuatuVenezuela, Bolivarian Republic ofVietnamVirgin Islands, BritishWallis and FutunaWestern SaharaYemenZambiaZimbabweI also wish to receive emails from AAAS/Science and Science advertisers, including information on products, services and special offers which may include but are not limited to news, careers information & upcoming events.Required fields are included by an asterisk(*) On the subject of Alzheimer’s disease, the panel chastised NIH officials for plans to boost research in the field by snagging $80 million from a $500 million Prevention and Public Health (PPH) Fund created by health care reform legislation. “NIH research is not an appropriate use of the PPH Fund,” it wrote. “Additionally, the Committee believes it would set a dangerous precedent to provide specific amounts of NIH funding for individual diseases. The Committee notes that it took the same position in fiscal year 2010 when the administration proposed allocating specific levels of funding for cancer and autism research.” The bill must still be approved by the full Senate. The House appropriations panel has yet to introduce its version of the bill.last_img read more

No Easy Cure for Indian Cricket

first_imgThe miasma of corruption claims hanging over the Board of Control for Cricket in India, by far the most powerful body in the game because of its financial clout, is not going away any time soon. Related Itemslast_img

Artificial muscle can heal itself

first_imgMaterials scientists would kill to be able to produce a material as amazing as biological muscle, which can retract on command, stretch by about 70% without damage, and heal its own nicks and tears. Now, researchers say they’re getting closer with a synthetic material that can do all these things, though not as well as natural muscle. The advance could one day be useful in robotics and prosthetics.The concept of an artificial muscle dates back decades. Researchers have proposed numerous different starting materials, from atom-thick tubes of carbon called nanotubes to ceramics to metal alloys. In 2000, scientists showed that some rubberlike polymers called elastomers could be reversibly stretched to up to three times their length by applying a voltage across them. Like almost all synthetic materials, however, these elastomers needed someone to fix them if they were damaged. Working separately, other scientists have used elastomers as the basis for self-healing polymers—materials that can repair tears, seal holes, and even join cut edges. However, most of these have been quite weak and lacked elasticity, making them poor artificial muscles. And nobody has produced an artificial muscle that can repair itself.Until now, that is. Materials chemist Zhenan Bao of Stanford University in Palo Alto, California, and colleagues unveil today in Nature Chemistry a group of elastomers called Fe-Hpdca-PDMS. The material comprises long, randomly entangled polymer chains containing silicon, oxygen, nitrogen, and carbon atoms mixed with an iron salt. The iron forms chemical bonds with the oxygen and the nitrogen atoms in the polymer, joining the polymer chains both to themselves and to each other, like strings joined with elastic bands at the crossing points. These crosslinks do not prevent the polymer chains from moving altogether, so the material can stretch. But the crosslinks do stop the chains from sliding completely freely. For the material to change shape, the crosslinks have to be stretched, distorted, and sometimes broken and rearranged. When the material is done stretching, the crosslinks return to their original shape, giving the material both strength and elasticity.Sign up for our daily newsletterGet more great content like this delivered right to you!Country *AfghanistanAland IslandsAlbaniaAlgeriaAndorraAngolaAnguillaAntarcticaAntigua and BarbudaArgentinaArmeniaArubaAustraliaAustriaAzerbaijanBahamasBahrainBangladeshBarbadosBelarusBelgiumBelizeBeninBermudaBhutanBolivia, Plurinational State ofBonaire, Sint Eustatius and SabaBosnia and HerzegovinaBotswanaBouvet IslandBrazilBritish Indian Ocean TerritoryBrunei DarussalamBulgariaBurkina FasoBurundiCambodiaCameroonCanadaCape VerdeCayman IslandsCentral African RepublicChadChileChinaChristmas IslandCocos (Keeling) IslandsColombiaComorosCongoCongo, The Democratic Republic of theCook IslandsCosta RicaCote D’IvoireCroatiaCubaCuraçaoCyprusCzech RepublicDenmarkDjiboutiDominicaDominican RepublicEcuadorEgyptEl SalvadorEquatorial GuineaEritreaEstoniaEthiopiaFalkland Islands (Malvinas)Faroe IslandsFijiFinlandFranceFrench GuianaFrench PolynesiaFrench Southern TerritoriesGabonGambiaGeorgiaGermanyGhanaGibraltarGreeceGreenlandGrenadaGuadeloupeGuatemalaGuernseyGuineaGuinea-BissauGuyanaHaitiHeard Island and Mcdonald IslandsHoly See (Vatican City State)HondurasHong KongHungaryIcelandIndiaIndonesiaIran, Islamic Republic ofIraqIrelandIsle of ManIsraelItalyJamaicaJapanJerseyJordanKazakhstanKenyaKiribatiKorea, Democratic People’s Republic ofKorea, Republic ofKuwaitKyrgyzstanLao People’s Democratic RepublicLatviaLebanonLesothoLiberiaLibyan Arab JamahiriyaLiechtensteinLithuaniaLuxembourgMacaoMacedonia, The Former Yugoslav Republic ofMadagascarMalawiMalaysiaMaldivesMaliMaltaMartiniqueMauritaniaMauritiusMayotteMexicoMoldova, Republic ofMonacoMongoliaMontenegroMontserratMoroccoMozambiqueMyanmarNamibiaNauruNepalNetherlandsNew CaledoniaNew ZealandNicaraguaNigerNigeriaNiueNorfolk IslandNorwayOmanPakistanPalestinianPanamaPapua New GuineaParaguayPeruPhilippinesPitcairnPolandPortugalQatarReunionRomaniaRussian FederationRWANDASaint Barthélemy Saint Helena, Ascension and Tristan da CunhaSaint Kitts and NevisSaint LuciaSaint Martin (French part)Saint Pierre and MiquelonSaint Vincent and the GrenadinesSamoaSan MarinoSao Tome and PrincipeSaudi ArabiaSenegalSerbiaSeychellesSierra LeoneSingaporeSint Maarten (Dutch part)SlovakiaSloveniaSolomon IslandsSomaliaSouth AfricaSouth Georgia and the South Sandwich IslandsSouth SudanSpainSri LankaSudanSurinameSvalbard and Jan MayenSwazilandSwedenSwitzerlandSyrian Arab RepublicTaiwanTajikistanTanzania, United Republic ofThailandTimor-LesteTogoTokelauTongaTrinidad and TobagoTunisiaTurkeyTurkmenistanTurks and Caicos IslandsTuvaluUgandaUkraineUnited Arab EmiratesUnited KingdomUnited StatesUruguayUzbekistanVanuatuVenezuela, Bolivarian Republic ofVietnamVirgin Islands, BritishWallis and FutunaWestern SaharaYemenZambiaZimbabweI also wish to receive emails from AAAS/Science and Science advertisers, including information on products, services and special offers which may include but are not limited to news, careers information & upcoming events.Required fields are included by an asterisk(*)Then there’s the self-healing. If you poke a hole in the material, iron atoms on one side of the hole are attracted to oxygen and nitrogen atoms on the other, reforming atomic bonds and closing up the hole within 72 hours. Even when the researchers cut the polymers into two separate pieces, the cut edges ends rejoined almost perfectly if they were placed in contact, recovering almost all of their strength and 90% of their stretchability, even at temperatures as low as -20°C.When the researchers applied an electric field across the polymers (similar to how muscle tissue is activated), the material’s length increased rapidly by about 2%. When the field was turned off, the material returned to its original size.One notable weakness of the material is that the change in size after the electric field was applied is still small: Even though the material can normally be stretched up to 45 times its original length and still return to its original shape, its change in size when the field was turned on was much smaller than that of real muscle (which can shorten by up to 40%). This would mean that those robotic legs couldn’t bend nearly as well as natural ones.“In our case, the goal was not to make the best artificial muscle, but rather to develop new materials design rules for stretchable and self-healing materials,” Bao explains. “Artificial muscle is one potential application for our materials.” Bao’s team is now planning further work on increasing the effects of electric fields.“It’s very interesting and extremely elegant work,” says polymer chemist Marek Urban of Clemson University in South Carolina. He says the polymer could eventually be used to make the synthetic muscles needed to move artificial limbs, either to replace missing ones for disabled humans or to allow robots to move things like a human can. He also says the material might have other applications. Materials that expand and contract in response to an electric field are often used as pressure or strain sensors, sometimes self-correcting ones. Self-healing could be useful when sensors have to be placed in extreme conditions such as in space, where repair is sometimes difficult or impossible. “If a material has to be placed in an environment where there’s a potential for damage [and] that material self-repairs, that’s a huge advantage,” Urban says.last_img read more

Spacecraft reveal aurora near Jupiter’s south pole

first_img Our solar system’s largest planet is big enough for massive light shows—one at each pole, new research reveals. Scientists already knew that Jupiter sported an aurora in its northern hemisphere—one that is permanent, large enough to swallow Earth, and hundreds of times brighter than the ephemeral glows our planet hosts at each pole. Now, a new analysis of data gleaned by Earth-orbiting x-ray telescopes in 2007 and 2016 reveals that the gas giant hosts a second aurora on its southern end. Earth’s magnetic field isn’t strong enough to generate an aurora at x-ray wavelengths. Unlike Earth’s auroras, Jupiter’s are not in sync, researchers report today in Nature Astronomy. Whereas the newly discovered southern hot spot (seen at infrared wavelengths by instruments on the Juno probe now orbiting Jupiter) pulses once every 9 to 11 minutes, the northern x-ray hot spot has, in the past, been observed pulsing at rates of once every 12 minutes, once every 26 minutes, and once every 40 to 45 minutes. Researchers aren’t quite sure why Jupiter’s auroras aren’t synchronized: Among some possibilities, the researchers say, the disparity could stem from the immense size or strength of the planet’s magnetic field, or may simply result from unexpected processes that help generate the auroras. Sign up for our daily newsletterGet more great content like this delivered right to you!Country *AfghanistanAland IslandsAlbaniaAlgeriaAndorraAngolaAnguillaAntarcticaAntigua and BarbudaArgentinaArmeniaArubaAustraliaAustriaAzerbaijanBahamasBahrainBangladeshBarbadosBelarusBelgiumBelizeBeninBermudaBhutanBolivia, Plurinational State ofBonaire, Sint Eustatius and SabaBosnia and HerzegovinaBotswanaBouvet IslandBrazilBritish Indian Ocean TerritoryBrunei DarussalamBulgariaBurkina FasoBurundiCambodiaCameroonCanadaCape VerdeCayman IslandsCentral African RepublicChadChileChinaChristmas IslandCocos (Keeling) IslandsColombiaComorosCongoCongo, The Democratic Republic of theCook IslandsCosta RicaCote D’IvoireCroatiaCubaCuraçaoCyprusCzech RepublicDenmarkDjiboutiDominicaDominican RepublicEcuadorEgyptEl SalvadorEquatorial GuineaEritreaEstoniaEthiopiaFalkland Islands (Malvinas)Faroe IslandsFijiFinlandFranceFrench GuianaFrench PolynesiaFrench Southern TerritoriesGabonGambiaGeorgiaGermanyGhanaGibraltarGreeceGreenlandGrenadaGuadeloupeGuatemalaGuernseyGuineaGuinea-BissauGuyanaHaitiHeard Island and Mcdonald IslandsHoly See (Vatican City State)HondurasHong KongHungaryIcelandIndiaIndonesiaIran, Islamic Republic ofIraqIrelandIsle of ManIsraelItalyJamaicaJapanJerseyJordanKazakhstanKenyaKiribatiKorea, Democratic People’s Republic ofKorea, Republic ofKuwaitKyrgyzstanLao People’s Democratic RepublicLatviaLebanonLesothoLiberiaLibyan Arab JamahiriyaLiechtensteinLithuaniaLuxembourgMacaoMacedonia, The Former Yugoslav Republic ofMadagascarMalawiMalaysiaMaldivesMaliMaltaMartiniqueMauritaniaMauritiusMayotteMexicoMoldova, Republic ofMonacoMongoliaMontenegroMontserratMoroccoMozambiqueMyanmarNamibiaNauruNepalNetherlandsNew CaledoniaNew ZealandNicaraguaNigerNigeriaNiueNorfolk IslandNorwayOmanPakistanPalestinianPanamaPapua New GuineaParaguayPeruPhilippinesPitcairnPolandPortugalQatarReunionRomaniaRussian FederationRWANDASaint Barthélemy Saint Helena, Ascension and Tristan da CunhaSaint Kitts and NevisSaint LuciaSaint Martin (French part)Saint Pierre and MiquelonSaint Vincent and the GrenadinesSamoaSan MarinoSao Tome and PrincipeSaudi ArabiaSenegalSerbiaSeychellesSierra LeoneSingaporeSint Maarten (Dutch part)SlovakiaSloveniaSolomon IslandsSomaliaSouth AfricaSouth Georgia and the South Sandwich IslandsSouth SudanSpainSri LankaSudanSurinameSvalbard and Jan MayenSwazilandSwedenSwitzerlandSyrian Arab RepublicTaiwanTajikistanTanzania, United Republic ofThailandTimor-LesteTogoTokelauTongaTrinidad and TobagoTunisiaTurkeyTurkmenistanTurks and Caicos IslandsTuvaluUgandaUkraineUnited Arab EmiratesUnited KingdomUnited StatesUruguayUzbekistanVanuatuVenezuela, Bolivarian Republic ofVietnamVirgin Islands, BritishWallis and FutunaWestern SaharaYemenZambiaZimbabweI also wish to receive emails from AAAS/Science and Science advertisers, including information on products, services and special offers which may include but are not limited to news, careers information & upcoming events.Required fields are included by an asterisk(*) Spacecraft reveal aurora near Jupiter’s south pole By Sid PerkinsOct. 30, 2017 , 12:00 PMcenter_img NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM last_img read more

Why does evolution sometimes repeat itself? Spider-eating spiders may hold the answer

first_img George Roderick Why does evolution sometimes repeat itself? Spider-eating spiders may hold the answer Hawaiian stick spiders repeatedly evolved colors to match their backgrounds to hide from predators. Discovering something for the second time might sound like a letdown. Not for ecologists in Hawaii, who have found that spider-eating spiders on four islands there independently evolved the same colors: gold, black, and white. This rare example of parallel evolution, which has also been seen in one other Hawaiian spider, could help clarify one of biology’s biggest mysteries: how and when evolution repeats itself.“It’s one of the coolest hidden [examples] of animals evolving new species,” says Robert Fleischer, a conservation genomicist at the Smithsonian Conservation Biology Institute in Washington, D.C., who was not involved with the work.Hawaii is a great place to study evolution. Any animal that washes up or flies there may be separated from its kin by thousands of kilometers, a great opportunity for the formation of new species. And every island within the archipelago is yet another opportunity to diversify as new arrivals move into habitats not yet taken over by other organisms.Sign up for our daily newsletterGet more great content like this delivered right to you!Country *AfghanistanAland IslandsAlbaniaAlgeriaAndorraAngolaAnguillaAntarcticaAntigua and BarbudaArgentinaArmeniaArubaAustraliaAustriaAzerbaijanBahamasBahrainBangladeshBarbadosBelarusBelgiumBelizeBeninBermudaBhutanBolivia, Plurinational State ofBonaire, Sint Eustatius and SabaBosnia and HerzegovinaBotswanaBouvet IslandBrazilBritish Indian Ocean TerritoryBrunei DarussalamBulgariaBurkina FasoBurundiCambodiaCameroonCanadaCape VerdeCayman IslandsCentral African RepublicChadChileChinaChristmas IslandCocos (Keeling) IslandsColombiaComorosCongoCongo, The Democratic Republic of theCook IslandsCosta RicaCote D’IvoireCroatiaCubaCuraçaoCyprusCzech RepublicDenmarkDjiboutiDominicaDominican RepublicEcuadorEgyptEl SalvadorEquatorial GuineaEritreaEstoniaEthiopiaFalkland Islands (Malvinas)Faroe IslandsFijiFinlandFranceFrench GuianaFrench PolynesiaFrench Southern TerritoriesGabonGambiaGeorgiaGermanyGhanaGibraltarGreeceGreenlandGrenadaGuadeloupeGuatemalaGuernseyGuineaGuinea-BissauGuyanaHaitiHeard Island and Mcdonald IslandsHoly See (Vatican City State)HondurasHong KongHungaryIcelandIndiaIndonesiaIran, Islamic Republic ofIraqIrelandIsle of ManIsraelItalyJamaicaJapanJerseyJordanKazakhstanKenyaKiribatiKorea, Democratic People’s Republic ofKorea, Republic ofKuwaitKyrgyzstanLao People’s Democratic RepublicLatviaLebanonLesothoLiberiaLibyan Arab JamahiriyaLiechtensteinLithuaniaLuxembourgMacaoMacedonia, The Former Yugoslav Republic ofMadagascarMalawiMalaysiaMaldivesMaliMaltaMartiniqueMauritaniaMauritiusMayotteMexicoMoldova, Republic ofMonacoMongoliaMontenegroMontserratMoroccoMozambiqueMyanmarNamibiaNauruNepalNetherlandsNew CaledoniaNew ZealandNicaraguaNigerNigeriaNiueNorfolk IslandNorwayOmanPakistanPalestinianPanamaPapua New GuineaParaguayPeruPhilippinesPitcairnPolandPortugalQatarReunionRomaniaRussian FederationRWANDASaint Barthélemy Saint Helena, Ascension and Tristan da CunhaSaint Kitts and NevisSaint LuciaSaint Martin (French part)Saint Pierre and MiquelonSaint Vincent and the GrenadinesSamoaSan MarinoSao Tome and PrincipeSaudi ArabiaSenegalSerbiaSeychellesSierra LeoneSingaporeSint Maarten (Dutch part)SlovakiaSloveniaSolomon IslandsSomaliaSouth AfricaSouth Georgia and the South Sandwich IslandsSouth SudanSpainSri LankaSudanSurinameSvalbard and Jan MayenSwazilandSwedenSwitzerlandSyrian Arab RepublicTaiwanTajikistanTanzania, United Republic ofThailandTimor-LesteTogoTokelauTongaTrinidad and TobagoTunisiaTurkeyTurkmenistanTurks and Caicos IslandsTuvaluUgandaUkraineUnited Arab EmiratesUnited KingdomUnited StatesUruguayUzbekistanVanuatuVenezuela, Bolivarian Republic ofVietnamVirgin Islands, BritishWallis and FutunaWestern SaharaYemenZambiaZimbabweI also wish to receive emails from AAAS/Science and Science advertisers, including information on products, services and special offers which may include but are not limited to news, careers information & upcoming events.Required fields are included by an asterisk(*)So it is with a genus of spiders known as Ariamnes. The up-to-2-centimeter-size forest dwellers, which can camouflage themselves to look like sticks, probably arrived in Hawaii within the past 5 million years. Since then, they have differentiated into numerous species spread out over four islands.To get a better sense of how these species evolved, Rosemary Gillespie, an evolutionary ecologist at the University of California, Berkeley, and her colleagues obtained DNA from individuals of each species. All four islands—Oahu, Kauai, Maui, and the Big Island of Hawaii—are home to shiny gold and dark species of the spider, and two have an additional dull white version. Gillespie’s team identified four entirely new species, making 15 in all.Logic would dictate that the spiders that look most alike—i.e., those of the same color—would be the most closely related. But when Gillespie’s team built a family tree from the genetic data, the closest relatives were spiders living on the same island, the team reports today in Current Biology. Thus, each island was likely colonized by one spider that then diversified into the different-colored species.The researchers suspect that the first Ariamnes was dark or gold, and that it landed on one of the oldest islands to form, perhaps Kauai, before spreading somehow to Oahu and eventually to the younger Maui and the Big Island. That first spider likely lived on the webs of other spiders, stealing snagged prey and sometimes chowing down on the web’s owner. Once in Hawaii, Ariamnes began to roam and hunt.The results parallel another study of Hawaii’s “spiny leg” Tetragnatha spiders, also by Gillespie. In one group of this genus of long-jawed spiders, where and what they hunt determines their colors: green, maroon, or brown.But evolution did not repeat itself in a different group of Tetragnatha spiders that also diversified in Hawaii. Now, Gillespie thinks she knows why. That other group of Tetragnatha spiders are typical, web-building spiders that don’t have to find a place to hide from birds during the day. Webless spiders like Ariamnes and the spiny leg Tetragnatha must very rapidly develop the protective coloration that matches where they hide out. The white species typically rest on pale lichens and the gold ones on the undersides of leaves, where their shininess makes them reflect the leaf’s colors. And the dark ones live under dead ferns or in moss.“This underscores how a rich environment having few other species spurs rapid evolution in the few [organisms] that by chance managed to get there,” says Dolph Schluter, an evolutionary biologist at the University of British Columbia in Vancouver, Canada, who was not involved in the study. According to Schluter, most researchers had thought it was primarily competition for food that drove species to diversify and adapt. But here, predation seems key, he adds, and may have even been a “crucial step” in the origin of species that are heavily hunted. Matching the background is so important, that evolution does tend to repeat itself in those situations.The results may even help scientists predict how other organisms might evolve in parallel to evade predators, the researchers say and help explain why evolution repeats itself sometimes but not other times. But what would be really interesting, says Fleischer, is if Gillespie’s team can identify the genes and the mutations responsible for the color changes. “That would be the Holy Grail.” By Elizabeth PennisiMar. 8, 2018 , 12:00 PMlast_img read more

Lab-grown patch of heart muscle and other cells could fix ailing hearts

first_img Lab-grown patch of heart muscle and other cells could fix ailing hearts BURSAC LAB/DUKE UNIVERSITY A patch of lab-grown human heart tissue (left) has holes near its edges to make it easier to attach to a damaged heart. A magnified look at one implanted on a mouse heart shows the patch’s capillaries (red) nourishing its muscle cells (green). By Elizabeth PennisiApr. 24, 2019 , 4:30 PM Every 40 seconds, someone in the United States has a heart attack. Each time, up to a billion heart muscle cells suffocate. Those lost cells never regrow, leaving almost 800,000 people a year impaired for life—if they survive at all. Nenad Bursac believes he can patch some of those people up, literally.Over the past 20 years, the bioengineer from Duke University in Durham, North Carolina, has been developing a “patch” that could take the place of the cells destroyed by a heart attack. In rodents, he has found it can hook up to the circulatory system and contract. Bursac’s patch is now about the size of a poker chip and the thickness of cardboard—big and complex enough to be tested in large animals, he declared this month at the Experimental Biology 2019 meeting in Orlando, Florida.Like others attempting to repair damaged hearts, Bursac starts with stem cells, which can develop into specialized tissues such as heart muscle. But whereas some researchers inject hundreds of millions of individual heart muscle cells into the body, Bursac’s team and several other groups grow full-fledged pieces of heart muscle in a dish, which surgeons could attach to a damaged heart. “This could be a transformative approach,” says Ralph Marcucio, a developmental biologist at the University of California, San Francisco, School of Medicine. Bursac’s research effort “is the best in the field,” adds Martine Dunnwald, a cell biologist at the University of Iowa in Iowa City.Sign up for our daily newsletterGet more great content like this delivered right to you!Country *AfghanistanAland IslandsAlbaniaAlgeriaAndorraAngolaAnguillaAntarcticaAntigua and BarbudaArgentinaArmeniaArubaAustraliaAustriaAzerbaijanBahamasBahrainBangladeshBarbadosBelarusBelgiumBelizeBeninBermudaBhutanBolivia, Plurinational State ofBonaire, Sint Eustatius and SabaBosnia and HerzegovinaBotswanaBouvet IslandBrazilBritish Indian Ocean TerritoryBrunei DarussalamBulgariaBurkina FasoBurundiCambodiaCameroonCanadaCape VerdeCayman IslandsCentral African RepublicChadChileChinaChristmas IslandCocos (Keeling) IslandsColombiaComorosCongoCongo, The Democratic Republic of theCook IslandsCosta RicaCote D’IvoireCroatiaCubaCuraçaoCyprusCzech RepublicDenmarkDjiboutiDominicaDominican RepublicEcuadorEgyptEl SalvadorEquatorial GuineaEritreaEstoniaEthiopiaFalkland Islands (Malvinas)Faroe IslandsFijiFinlandFranceFrench GuianaFrench PolynesiaFrench Southern TerritoriesGabonGambiaGeorgiaGermanyGhanaGibraltarGreeceGreenlandGrenadaGuadeloupeGuatemalaGuernseyGuineaGuinea-BissauGuyanaHaitiHeard Island and Mcdonald IslandsHoly See (Vatican City State)HondurasHong KongHungaryIcelandIndiaIndonesiaIran, Islamic Republic ofIraqIrelandIsle of ManIsraelItalyJamaicaJapanJerseyJordanKazakhstanKenyaKiribatiKorea, Democratic People’s Republic ofKorea, Republic ofKuwaitKyrgyzstanLao People’s Democratic RepublicLatviaLebanonLesothoLiberiaLibyan Arab JamahiriyaLiechtensteinLithuaniaLuxembourgMacaoMacedonia, The Former Yugoslav Republic ofMadagascarMalawiMalaysiaMaldivesMaliMaltaMartiniqueMauritaniaMauritiusMayotteMexicoMoldova, Republic ofMonacoMongoliaMontenegroMontserratMoroccoMozambiqueMyanmarNamibiaNauruNepalNetherlandsNew CaledoniaNew ZealandNicaraguaNigerNigeriaNiueNorfolk IslandNorwayOmanPakistanPalestinianPanamaPapua New GuineaParaguayPeruPhilippinesPitcairnPolandPortugalQatarReunionRomaniaRussian FederationRWANDASaint Barthélemy Saint Helena, Ascension and Tristan da CunhaSaint Kitts and NevisSaint LuciaSaint Martin (French part)Saint Pierre and MiquelonSaint Vincent and the GrenadinesSamoaSan MarinoSao Tome and PrincipeSaudi ArabiaSenegalSerbiaSeychellesSierra LeoneSingaporeSint Maarten (Dutch part)SlovakiaSloveniaSolomon IslandsSomaliaSouth AfricaSouth Georgia and the South Sandwich IslandsSouth SudanSpainSri LankaSudanSurinameSvalbard and Jan MayenSwazilandSwedenSwitzerlandSyrian Arab RepublicTaiwanTajikistanTanzania, United Republic ofThailandTimor-LesteTogoTokelauTongaTrinidad and TobagoTunisiaTurkeyTurkmenistanTurks and Caicos IslandsTuvaluUgandaUkraineUnited Arab EmiratesUnited KingdomUnited StatesUruguayUzbekistanVanuatuVenezuela, Bolivarian Republic ofVietnamVirgin Islands, BritishWallis and FutunaWestern SaharaYemenZambiaZimbabweI also wish to receive emails from AAAS/Science and Science advertisers, including information on products, services and special offers which may include but are not limited to news, careers information & upcoming events.Required fields are included by an asterisk(*)At one point, cardiologists thought the heart had a secret stash of stem cells that could be stimulated to repair the organ naturally, but now most biologists agree such cells don’t exist in the heart. An alternative in early clinical trials is to make heart muscle cells in a lab dish from other stem cells, inject them into the artery supplying the heart, and hope they settle in the organ and compensate for any dead tissue.Bursac is skeptical of that approach, because the percentage of cells that survive injection and make it to the heart is very small. His approach requires open-heart surgery, but it delivers a repair that more closely matches the cell types and architecture of the real organ. “What people are now seeing is you need more structure and more cells,” says Jeffrey Jacot, a bioengineer at the University of Colorado Anschutz Medical Campus in Aurora.Bursac started to work on heart patches as a Ph.D. student, coaxing neonatal rat cells to transform into heart muscle in a dish and contract—a first for mammals. Other researchers developed tiny heart tissue swatches for testing drugs in lab dishes. But Bursac wants to fix hearts directly. Over the years, his team has learned the best scaffolds for culturing stem cells are made of fibrin, a protein that helps form blood clots, and the best way to nurture these scaffolded cells is to gently rock them inside a suspended frame that allows the growing patch to swish back and forth in liquid media. “These cells mature and become strongly contracting,” Bursac says.In 2016, when his lab figured out how to produce those powerful contractions, the heart patches were tiny. Then, 2 years ago, the team grew a 4-centimeter-by-4-centimeter patch—potentially big enough to repair a damaged human heart.”The size is exciting,” says Christopher Chen, a bioengineer at Boston University. It “suggests that you can get to a scale that is clinically relevant.”Bursac’s team also showed in rodents that blood vessels from the heart being treated can expand into the patch to keep it alive. Bursac has recently woven in more complexity, adding populations of endothelial cells, which develop into blood vessels, and fibroblast cells, which he realized can help the patch form and become stronger. A patch composed of 70% heart muscle cells, with the other two kinds of cells making up the rest, appears best so far, he reported at the meeting.When the patch is implanted in rats and mice, its capillary network hooks up with the rodent’s circulatory system, he reported. “But we still don’t know if this can provide a survival advantage to the patch.”Nor is it clear how—or even whether—a patch will become electrically and mechanically integrated with the original heart so they function as a true unit. Because the patch would be stitched to the outside of a damaged heart, over the scar tissue, “it is difficult to have [it] beat coordinately with existing muscle,” points out Katherine Yutzey, a cardiac biologist at Cincinnati Children’s Hospital in Ohio.Answers may come from tests of these human heart patches in pigs or other large animals, which Bursac is conducting with bioengineer Jianyi Zhang at the University of Alabama in Birmingham. But Michelle Tallquist, a cardiovascular biologist at the University of Hawaii John A. Burns School of Medicine in Honolulu, worries that producing a patch for someone who has just suffered a heart attack could take too long—as much as 6 months if the patient’s own cells were used as the starting point.Bursac thinks the answer could be to develop a bank of immunologically matched stem cells, which might be coaxed as needed into a heart patch in as few as 3 weeks. For him, the prize is clear. The patch can “replace dead heart cells with cells that are alive and beat and contract,” he explains. “You can see now that this could potentially go to therapy.”last_img read more

Clubby and ‘disturbing’ citation behavior by researchers in Italy has surged

first_imgItaly 20222426283032% Clubby and ‘disturbing’ citation behavior by researchers in Italy has surged The rate at which scientists in Italy cite themselves and their compatriots is rising faster than in 10 other developed countries, according to a new study. The surge in Italy’s clubby citation behavior is likely the result of a 2010 law requiring productivity standards for academic recruitment or promotion, the study authors say.The findings are a cautionary tale for research administrators who rely too much on citation metrics in allocating resources and making decisions on career advancement, says study author Giuseppe De Nicolao, an engineer at the University of Pavia in Italy. Linking professional advancement to citation indicators can prod scientists into unintended behaviors and make the metrics unreliable, he says.The findings are “disturbing,” says Ludo Waltman, a bibliometric expert at Leiden University in the Netherlands who was not involved in the study. To limit questionable citation practices, Waltman says, the Italian evaluation system should exclude self-citations and consider factors such as a researcher’s experience and activities in addition to citation counts.Sign up for our daily newsletterGet more great content like this delivered right to you!Country *AfghanistanAland IslandsAlbaniaAlgeriaAndorraAngolaAnguillaAntarcticaAntigua and BarbudaArgentinaArmeniaArubaAustraliaAustriaAzerbaijanBahamasBahrainBangladeshBarbadosBelarusBelgiumBelizeBeninBermudaBhutanBolivia, Plurinational State ofBonaire, Sint Eustatius and SabaBosnia and HerzegovinaBotswanaBouvet IslandBrazilBritish Indian Ocean TerritoryBrunei DarussalamBulgariaBurkina FasoBurundiCambodiaCameroonCanadaCape VerdeCayman IslandsCentral African RepublicChadChileChinaChristmas IslandCocos (Keeling) IslandsColombiaComorosCongoCongo, The Democratic Republic of theCook IslandsCosta RicaCote D’IvoireCroatiaCubaCuraçaoCyprusCzech RepublicDenmarkDjiboutiDominicaDominican RepublicEcuadorEgyptEl SalvadorEquatorial GuineaEritreaEstoniaEthiopiaFalkland Islands (Malvinas)Faroe IslandsFijiFinlandFranceFrench GuianaFrench PolynesiaFrench Southern TerritoriesGabonGambiaGeorgiaGermanyGhanaGibraltarGreeceGreenlandGrenadaGuadeloupeGuatemalaGuernseyGuineaGuinea-BissauGuyanaHaitiHeard Island and Mcdonald IslandsHoly See (Vatican City State)HondurasHong KongHungaryIcelandIndiaIndonesiaIran, Islamic Republic ofIraqIrelandIsle of ManIsraelItalyJamaicaJapanJerseyJordanKazakhstanKenyaKiribatiKorea, Democratic People’s Republic ofKorea, Republic ofKuwaitKyrgyzstanLao People’s Democratic RepublicLatviaLebanonLesothoLiberiaLibyan Arab JamahiriyaLiechtensteinLithuaniaLuxembourgMacaoMacedonia, The Former Yugoslav Republic ofMadagascarMalawiMalaysiaMaldivesMaliMaltaMartiniqueMauritaniaMauritiusMayotteMexicoMoldova, Republic ofMonacoMongoliaMontenegroMontserratMoroccoMozambiqueMyanmarNamibiaNauruNepalNetherlandsNew CaledoniaNew ZealandNicaraguaNigerNigeriaNiueNorfolk IslandNorwayOmanPakistanPalestinianPanamaPapua New GuineaParaguayPeruPhilippinesPitcairnPolandPortugalQatarReunionRomaniaRussian FederationRWANDASaint Barthélemy Saint Helena, Ascension and Tristan da CunhaSaint Kitts and NevisSaint LuciaSaint Martin (French part)Saint Pierre and MiquelonSaint Vincent and the GrenadinesSamoaSan MarinoSao Tome and PrincipeSaudi ArabiaSenegalSerbiaSeychellesSierra LeoneSingaporeSint Maarten (Dutch part)SlovakiaSloveniaSolomon IslandsSomaliaSouth AfricaSouth Georgia and the South Sandwich IslandsSouth SudanSpainSri LankaSudanSurinameSvalbard and Jan MayenSwazilandSwedenSwitzerlandSyrian Arab RepublicTaiwanTajikistanTanzania, United Republic ofThailandTimor-LesteTogoTokelauTongaTrinidad and TobagoTunisiaTurkeyTurkmenistanTurks and Caicos IslandsTuvaluUgandaUkraineUnited Arab EmiratesUnited KingdomUnited StatesUruguayUzbekistanVanuatuVenezuela, Bolivarian Republic ofVietnamVirgin Islands, BritishWallis and FutunaWestern SaharaYemenZambiaZimbabweI also wish to receive emails from AAAS/Science and Science advertisers, including information on products, services and special offers which may include but are not limited to news, careers information & upcoming events.Required fields are included by an asterisk(*) After the 2010 law was passed, Italy began to regulate academic recruitment and promotion using indicators such as citation counts. It was intended to address concerns about nepotism and a lack of meritocracy.Under the policy, academics can’t seek a job or a promotion as an associate or full professor unless they meet at least two of three indicators of research productivity. In fields such as medicine and natural sciences, these indicators include the number of publications, the number of citations received, and h-index—a combined measure of productivity and citation impact. 2010 2008 Mark Airs/Getty Images FranceInwardness 2014center_img United Kingdom 2016 Japan Graphic: J. Brainard/Science; Data: A. Baccine et al.; PLOS ONE 2012 By Giorgia GuglielmiSep. 11, 2019 , 2:00 PM Citations turn inward Compared with other countries, Italy saw a faster rise in “inwardness,” the percentage of citations to a country’s scientific articles that came from authors in the same country. Previous studies have found that the 2010 policy induced a rise in self-citations. However, those studies didn’t look at the proportion of each country’s publications cited by other scholars within the same country, says Alberto Baccini, a scientometrics expert at the University of Siena in Italy. These intranational citations could reveal “citation clubs,” a subtle form of manipulation in which groups of scientists cite each other to boost their citation scores, Baccini says.So Baccini, De Nicolao, and their team set out to develop an indicator of inwardness, which measures both self-referential and intranational citations. The researchers scoured Elsevier’s Scopus database, one of the world’s largest for research literature, for citation counts between 2000 and 2016 for researchers in the G-10, a group of 11 developed countries. To calculate a nation’s inwardness, the team counted citations by a country’s authors to papers authored in that country and divided this figure by the total number of citations accrued by the country.All of the nations showed modest rises in inwardness over time, which can be explained, paradoxically, by a growth in international collaborations. These expand the number of papers from participating countries that could be cited. Take, for example, a paper co-authored by research collaborators in Italy and France: Any citation to this paper from an Italian- or French-authored publication will count as an intranational citation for both Italy and France.Beginning in 2010, however, Italy’s inwardness started to increase rapidly, surpassing France, Japan, and the United Kingdom, the researchers found. The surge could not be attributed to collaborations, because Italy’s rate of growth for international collaborations between 2000 and 2016 was anemic compared with other nations. By 2016, about 31% of the Italy’s citations came from authors within its borders—more than any other country except the United States, a research powerhouse where many intranational citations are expected.Because the trends changed after the introduction of the 2010 policy, it’s likely that authors in Italy adopted opportunistic behaviors, including massively citing their own work and that of colleagues, to reach their country’s policy targets, the researchers report today in PLOS ONE.Marco Seeber, a science policy researcher at the University of Ghent in Belgium, says the growth in Italy’s inwardness is “striking.” In March, Seeber investigated the country’s use of citation metrics and found substantial increases in self-citations after the 2010 policy. “The policy was motivated by worthy intentions,” he says. “But bibliometric indicators should be used to inform rather than determine evaluations.”Seeber says it’s unclear how much of Italy’s inwardness is from self-citation versus citation clubs. To uncover these clubs, one would need to examine individual papers to discriminate legitimate from bogus citations, he says.John Ioannidis, a physician-scientist at Stanford University in Palo Alto, California, suspects citation clubs are behind Italy’s trend. Ioannidis, who created a database that revealed hundreds of extreme self-citing researchers, says the new study provides yet another example of how metrics can be misused. He notes that self-citations are necessary if a study builds on previous work by the authors or their colleagues. “But if someone has amassed more than half of their citations from themselves or their co-authors, that’s pretty weird,” he says. “You have to take a closer look.”last_img read more

Martinez: Lukaku can do it all

first_imgBelgium CT Roberto Martinez has assured Inter fans that they have “a unique No 9 who knows how to do it all” in Romelu Lukaku. Lukaku became Inter’s record signing when he arrived from Manchester United in August and has made an immediate impact, already scoring five Serie A goals. “He’s a unique No 9, physically strong: I think it’s important for every team to have a striker who harvests all his qualities,” Martinez told Gazzetta dello Sport. “Romelu dribbles, holds the ball up and – above all – scores. Being able to surpass 100 goals in the Premier League and being Belgium’s all-time top scorer tells you everything. “This is what the Italian fans are starting to appreciate, a chameleon-like striker, able to do many things but always with the intention of scoring. “He knows how to do it all. Therefore, lots of people go around looking for the things he was unable to do. “There are strikers who know how to do only one thing, so no-one asks them to do anything else. “Romelu’s strength is that he can always do something different: this is also a disadvantage because there are games where some of the things he tries fail to come off. “He makes the pitch bigger and creates things for others: if people appreciated these things, even when he doesn’t score, then he’d be criticised less. “I invite fans to go back over his career: at 16 he was already scoring goals for Anderlecht, then at Everton ge was important, getting used to the physicality of the Premier League. “At that point, always putting the team before himself, he matured: now he’s ready to win a title abroad and I think that’s what he wants to do with Inter. “When you put something in your head, you get it.” For all the talk of ending Juventus’ grip on the Scudetto, the Belgian has yet to score in the Champions League this season… “History shows that Italian teams have had strong, physical defenders. Romelu is more used to the Champions League. “He’s been playing in it for a long time so I think he’ll find it less of a struggle, even if Borussia [Dortmund] have several top individuals.” Watch Serie A live in the UK on Premier Sports for just £11.99 per month including live LaLiga, Eredivisie, Scottish Cup Football and more. Visit: https://subscribe.premiersports.tv/last_img read more

Season over for Napoli’s Malcuit

first_img Watch Serie A live in the UK on Premier Sports for just £11.99 per month including live LaLiga, Eredivisie, Scottish Cup Football and more. Visit: https://subscribe.premiersports.tv/ Kévin Malcuit’s season is over after the Napoli defender damaged knee ligaments during the 1-1 draw with SPAL on Sunday. It was confirmed on Monday that Malcuit had injured both the ACL and medial meniscus in his right knee against SPAL. The Frenchman, who left the field in tears, will undergo surgery tomorrow and is not expected to play again for Napoli this season. He becomes the fourth defensive casualty for Carlo Ancelotti’s side, with Mario Rui, Nikola Maksimovic and Elseid Hysaj also out. Consequently, Ancelotti will have to turn back to Faouzi Ghoulam, who has fallen out of favour in recent weeks.last_img read more

Thuram: ‘Ban those who deny racism’

first_imgLilian Thuram is shocked by Verona’s reaction to the racist abuse aimed at Mario Balotelli, calling coach Ivan Juric “a very dangerous person who should be suspended.” The Brescia forward kicked the ball into the stands aimed at the precise section where audible ‘monkey noises’ were coming from during Sunday’s Serie A game at the Stadio Bentegodi. Despite the fact even the Federation representative on the touchline heard and reported the racist abuse, and it was caught on video, Juric, President Maurizio Setti and the Mayor of Verona all insisted there was no racism. “We have to tell people that there is history behind racism and it’s not true that it comes from ignorance,” former Parma and Juventus star Thuram told Radio 24. “History proves that racist people genuinely believe in these ideals, much like with sexism. If someone believes in the inferiority of another race or gender, he is not stupid, he genuinely believes in this. “It is also very dangerous to think of monkey noises as banter. It is not a normal thing to do. We need everyone to point that out, that this is unacceptable. “This is why I say the Verona coach is a very dangerous person who should be suspended for what he said. “He said that he didn’t hear anything wrong, that is the danger. When someone is attacked, others have to come to their aid, not expect the person under attack to defend himself. “When all the players walk off the pitch together, that is when things will change quickly. Racism is violence.” Hellas Verona did, however, ban ultras leader Luca Castellini until June 2030 after he used a series of racial slurs against Balotelli during an interview. “This gentleman says such things because there is history behind it, he believes nationality derives from the colour of your skin,” continued Thuram. “Racism is in the stadium, but what about society? Many say they are not racist, but do nothing for equality. The world of football must understand this is not a joke, it has real world consequences. “I’ve known racism before, during and after my playing career. What white player went to his fans and told them to stop it? Nobody. The only coach that I know who openly said he would walk off is Carlo Ancelotti. It is white players and coaches who must stand up and have the courage to say, enough is enough.” Watch Serie A live in the UK on Premier Sports for just £11.99 per month including live LaLiga, Eredivisie, Scottish Cup Football and more. Visit: https://subscribe.premiersports.tv/last_img read more

Go trekking this summer

first_imgRupika, 33, emailed to ask how she can stick to her workout routine when travelling. You have a regular fitness routine you’ve stuck with all year. Here come the holidays, and wreck your well-planned exercise regimen. But if you prioritise fitness and are flexible, you can manage things easily. A few tips:1. Use the outdoors and get moving. You could go for a walk through a specific neighbourhood or for a trek, since you mentioned that you are going to the hills. How about getting a group together for some tag races while you get that heart rate going?2. Break up your workout. Segment your workout into three 10-minute sessions that you can squeeze in each morning, noon and evening. Use the time you do have, even if it is five minutes.3. Have a plan B. If something thwarts your best intentions, have a backup plan. For example, tell yourself, ‘Tomorrow, I will walk at 4 pm, but if I’m still shopping, I’ll do it at 6:30 pm.’ If you typically exercise in the evening, you may want to switch your routine to mornings just during the holidays.4. Set realistic goals. Instead of working out five times a week, you may have to settle for three.Always have a pair of running or walking shoes with you, along with a set of light hand-held weights, and a clean pair of socks. If all else fails, you have the minimum equipment necessary to get in a walk.What matters is your total calorie consumption and the total calories expended over the entire holiday period. One or two splurges aren’t going to derail your efforts, so go ahead and have fun.advertisementNeesha Maria Bukht is a certified fitness trainer from the International Sports Sciences Association (ISSA). She works with Talwalkars Gym, Mumbai. Bukht writes regularly on fitness and is also a certified dietician. Write to her at Neesha.b@preventionindia.comlast_img read more

Sehwag’s uncle commits suicide

first_imgA 72-year-old uncle of cricketer Virender Sehwag allegedly committed suicide in his residence in south-west Delhi, apparently depressed over prolonged illness, police said on Friday.Bhagat Singh was found hanging at his residence in Laxmi Garden in Najafgarh on Tuesday night by his son Lalit Singh, who informed police.His body was taken to Rao Tula Ram Hospital where his post mortem was conducted.Singh, who had kidney-related problems, was apparently depressed over prolonged illness. However, he left no suicide note.He is survived by his wife, two sons and a daughter.last_img read more