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2005

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Articles 3511 - 3540 of 5573

Full-Text Articles in Physical Sciences and Mathematics

Spitzer Observations Of The Supergiant Shell Region In Ic 2574, John M. Cannon, F. Walter, G. J. Bendo, D. Calzetti, D. A. Dale, B. T. Draine, C. W. Engelbracht, K. D. Gordon, G. Helou, R. C. Kennicutt, E. J. Murphy, M. D. Thornley, L. Armus, D. J. Hollenbach, C. Leitherer, M. W. Regan, H. Roussel, K. Sheth Jan 2005

Spitzer Observations Of The Supergiant Shell Region In Ic 2574, John M. Cannon, F. Walter, G. J. Bendo, D. Calzetti, D. A. Dale, B. T. Draine, C. W. Engelbracht, K. D. Gordon, G. Helou, R. C. Kennicutt, E. J. Murphy, M. D. Thornley, L. Armus, D. J. Hollenbach, C. Leitherer, M. W. Regan, H. Roussel, K. Sheth

John Cannon

No abstract provided.

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Exclusive Photoproduction Of The Cascade (Xi) Hyperons, Jw Price, Bmk Nefkens, Jl Ducote, Jt Goetz, G Adams, P Ambrozewicz, E Anciant, M Anghinolfi, B Asavapibhop, G Audit, T Auger, H Avakian, H Bagdasaryan, Jp Ball, S Barrow, M Battaglieri, K Beard, M Bektasoglu, M Bellis, N Benmouna, Bl Berman, N Bianchi, As Biselli, S Boiarinov, S Bouchigny, R Bradford, D Branford, Wj Briscoe, Wk Brooks, Vd Burkert, C Butuceanu, Jr Calarco, Ds Carman, B Carnahan, C Cetina, S Chen, Pl Cole, A Coleman, J Connelly, D Cords, P Corvisiero, D Crabb, H Crannell, Jp Cummings, Ed Sanctis, R Devita, Pv Degtyarenko, H Denizli, L Dennis, Kv Dharmawardane, C Djalali, Ge Dodge, D Doughty, P Dragovitsch, M Dugger, S Dytman, Op Dzyubak, M Eckhause, H Egiyan, Ks Egiyan, L Elouadrhiri, A Empl, P Eugenio, L Farhi, R Fatemi, Rj Feuerbach, Ta Forest, V Frolov, H Funsten, Sj Gaff, G Gavalian, Gp Gilfoyle, Kl Giovanetti, Cio Gordon, R Gothe, K Griffioen, M Guidal, M Guillo, N Guler, L Guo, V Gyurjyan, C Hadjidakis, Rs Hakobyan, D Hancock, J Hardie, D Heddle, Fw Hersman, K Hicks, I Hleiqawi, M Holtrop, J Hu, Ce Hyde-Wright, Y Ilieva, D Ireland, Mm Ito, D Jenkins, K Joo, Hg Juengst, Jh Kelley, J Kellie, M Khandaker, Ky Kim, K Kim, W Kim, A Klein, Fj Klein, Av Klimenko, M Klusman, M Kossov, Lh Kramer, Y Kuang, V Kubarovsky, Se Kuhn, J Kuhn, J Lachniet, Jm Laget, J Langheinrich, D Lawrence, J Li, K Livingston, K Lukashin, W Major, Jj Manak, C Marchand, S Mcaleer, Jwc Mcnabb, Ba Mecking, Jj Melone, Md Mestayer, Ca Meyer, K Mikhailov, M Mirazita, R Miskimen, L Morand, Sa Morrow, V Muccifora, J Mueller, Gs Mutchler, J Napolitano, R Nasseripour, So Nelson, S Niccolai, G Niculescu, I Niculescu, Bb Niczyporuk, Ra Niyazov, M Nozar, Jt O'Brien, Gv O'Rielly, M Osipenko, A Ostrovidov, K Park, E Pasyuk, G Peterson, Sa Philips, N Pivnyuk, D Pocanic, O Pogorelko, E Polli, S Pozdniakov, Bm Preedom, Y Prok, D Protopopescu, Lm Qin, Ba Raue, G Riccardi, G Ricco, M Ripani, Bg Ritchie, F Ronchetti, G Rosner, P Rossi, D Rowntree, Pd Rubin, F Sabatie, K Sabourov, C Salgado, Jp Santoro, M Sanzone-Arenhovel, V Sapunenko, Ra Schumacher, Vs Serov, A Shafi, Yg Sharabian, J Shaw, S Simionatto, Av Skabelin, Es Smith, T Smith, Lc Smith, Di Sober, M Spraker, A Stavinsky, S Stepanyan, B Stokes, P Stoler, Ii Strakovsky, S Strauch, M Taiuti, S Taylor, Dj Tedeschi, U Thoma, R Thompson, A Tkabladze, L Todor, C Tur, M Ungaro, Mf Vineyard, Av Vlassov, K Wang, Lb Weinstein, H Weller, Dp Weygand, M Williams, M Witkowski, E Wolin, Mh Wood, A Yegneswaran, J Yun Jan 2005

Exclusive Photoproduction Of The Cascade (Xi) Hyperons, Jw Price, Bmk Nefkens, Jl Ducote, Jt Goetz, G Adams, P Ambrozewicz, E Anciant, M Anghinolfi, B Asavapibhop, G Audit, T Auger, H Avakian, H Bagdasaryan, Jp Ball, S Barrow, M Battaglieri, K Beard, M Bektasoglu, M Bellis, N Benmouna, Bl Berman, N Bianchi, As Biselli, S Boiarinov, S Bouchigny, R Bradford, D Branford, Wj Briscoe, Wk Brooks, Vd Burkert, C Butuceanu, Jr Calarco, Ds Carman, B Carnahan, C Cetina, S Chen, Pl Cole, A Coleman, J Connelly, D Cords, P Corvisiero, D Crabb, H Crannell, Jp Cummings, Ed Sanctis, R Devita, Pv Degtyarenko, H Denizli, L Dennis, Kv Dharmawardane, C Djalali, Ge Dodge, D Doughty, P Dragovitsch, M Dugger, S Dytman, Op Dzyubak, M Eckhause, H Egiyan, Ks Egiyan, L Elouadrhiri, A Empl, P Eugenio, L Farhi, R Fatemi, Rj Feuerbach, Ta Forest, V Frolov, H Funsten, Sj Gaff, G Gavalian, Gp Gilfoyle, Kl Giovanetti, Cio Gordon, R Gothe, K Griffioen, M Guidal, M Guillo, N Guler, L Guo, V Gyurjyan, C Hadjidakis, Rs Hakobyan, D Hancock, J Hardie, D Heddle, Fw Hersman, K Hicks, I Hleiqawi, M Holtrop, J Hu, Ce Hyde-Wright, Y Ilieva, D Ireland, Mm Ito, D Jenkins, K Joo, Hg Juengst, Jh Kelley, J Kellie, M Khandaker, Ky Kim, K Kim, W Kim, A Klein, Fj Klein, Av Klimenko, M Klusman, M Kossov, Lh Kramer, Y Kuang, V Kubarovsky, Se Kuhn, J Kuhn, J Lachniet, Jm Laget, J Langheinrich, D Lawrence, J Li, K Livingston, K Lukashin, W Major, Jj Manak, C Marchand, S Mcaleer, Jwc Mcnabb, Ba Mecking, Jj Melone, Md Mestayer, Ca Meyer, K Mikhailov, M Mirazita, R Miskimen, L Morand, Sa Morrow, V Muccifora, J Mueller, Gs Mutchler, J Napolitano, R Nasseripour, So Nelson, S Niccolai, G Niculescu, I Niculescu, Bb Niczyporuk, Ra Niyazov, M Nozar, Jt O'Brien, Gv O'Rielly, M Osipenko, A Ostrovidov, K Park, E Pasyuk, G Peterson, Sa Philips, N Pivnyuk, D Pocanic, O Pogorelko, E Polli, S Pozdniakov, Bm Preedom, Y Prok, D Protopopescu, Lm Qin, Ba Raue, G Riccardi, G Ricco, M Ripani, Bg Ritchie, F Ronchetti, G Rosner, P Rossi, D Rowntree, Pd Rubin, F Sabatie, K Sabourov, C Salgado, Jp Santoro, M Sanzone-Arenhovel, V Sapunenko, Ra Schumacher, Vs Serov, A Shafi, Yg Sharabian, J Shaw, S Simionatto, Av Skabelin, Es Smith, T Smith, Lc Smith, Di Sober, M Spraker, A Stavinsky, S Stepanyan, B Stokes, P Stoler, Ii Strakovsky, S Strauch, M Taiuti, S Taylor, Dj Tedeschi, U Thoma, R Thompson, A Tkabladze, L Todor, C Tur, M Ungaro, Mf Vineyard, Av Vlassov, K Wang, Lb Weinstein, H Weller, Dp Weygand, M Williams, M Witkowski, E Wolin, Mh Wood, A Yegneswaran, J Yun

Michael Williams

We report on the first measurement of exclusive Xi-(1321) hyperon photoproduction in gamma p --> K+ K+ Xi- for 3.2 < E(gamma) < 3.9 GeV. The final state is identified by the missing mass in p(gamma,K+ K+)X measured with the CLAS detector at Jefferson Laboratory. We have detected a significant number of the ground-state Xi-(1321)1/2+, and have estimated the total cross section for its production. We have also observed the first excited state Xi-(1530)3/2+. Photoproduction provides a copious source of Xi's. We discuss the possibilities of a search for the recently proposed Xi5-- and Xi5+ pentaquarks.

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Radiative Decays Of The Sigma(0)(1385) And Lambda(1520) Hyperons, S Taylor, Gs Mutchler, G Adams, P Ambrozewicz, E Anciant, M Anghinolfi, B Asavapibhop, G Asryan, G Audit, H Avakian, H Bagdasaryan, Jp Ball, S Barrow, V Batourine, M Battaglieri, K Beard, M Bektasoglu, M Bellis, N Benmouna, Bl Berman, N Bianchi, As Biselli, S Boiarinov, Be Bonner, S Bouchigny, R Bradford, D Branford, Wj Briscoe, Wk Brooks, S Bultmann, Vd Burkert, C Butuceanu, Jr Calarco, Ds Carman, B Carnahan, S Chen, Pl Cole, D Cords, P Corvisiero, D Crabb, H Crannell, Jp Cummings, E De Sanctis, R Devita, Pv Degtyarenko, H Denizli, L Dennis, A Deur, Kv Dharmawardane, C Djalali, Ge Dodge, D Doughty, P Dragovitsch, M Dugger, S Dytman, Op Dzyubak, H Egiyan, Ks Egiyan, L Elouadrhiri, A Empl, P Eugenio, R Fatemi, G Feldman, Rg Fersch, Rj Feuerbach, Ta Forest, H Funsten, M Garcon, G Gavalian, Gp Gilfoyle, Kl Giovanetti, E Golovatch, Cio Gordon, Rw Gothe, Ka Griffioen, M Guidal, M Guillo, N Guler, L Guo, V Gyurjyan, C Hadjidakis, Rs Hakobyan, J Hardie, D Heddle, Fw Hersman, K Hicks, I Hleiqawi, M Holtrop, J Hu, M Huertas, Ce Hyde-Wright, Y Ilieva, Dg Ireland, Mm Ito, D Jenkins, K Joo, Hg Juengst, Jd Kellie, M Khandaker, Ky Kim, K Kim, W Kim, A Klein, Fj Klein, Av Klimenko, M Klusman, M Kossov, V Koubarovski, Lh Kramer, Se Kuhn, J Kuhn, J Lachniet, Jm Laget, J Langheinrich, D Lawrence, T Lee, J Li, Acs Lima, K Livingston, K Lukashin, Jj Manak, C Marchand, S Mcaleer, Jwc Mcnabb, Ba Mecking, Jj Melone, Md Mestayer, Ca Meyer, K Mikhailov, M Mirazita, R Miskimen, V Mokeev, L Morand, Sa Morrow, V Muccifora, J Mueller, J Napolitano, R Nasseripour, S Niccolai, G Niculescu, I Niculescu, Bb Niczyporuk, Ra Niyazov, M Nozar, Gv O'Rielly, M Osipenko, Ai Ostrovidov, K Park, E Pasyuk, Sa Philips, N Pivnyuk, D Pocanic, O Pogorelko, E Polli, S Pozdniakov, Bm Preedom, Jw Price, Y Prok, D Protopopescu, Lm Qin, Bs Raue, G Riccardi, G Ricco, M Ripani, Bg Ritchie, F Ronchetti, G Rosner, P Rossi, D Rowntree, Pd Rubin, F Sabatie, C Salgado, Jp Santoro, V Sapunenko, Ra Schumacher, Vs Serov, A Shafi, Yg Sharabian, J Shaw, S Simionatto, Av Skabelin, Es Smith, Lc Smith, Di Sober, M Spraker, A Stavinsky, S Stepanyan, Ss Stepanyan, Be Stokes, P Stoler, Ii Strakovsky, S Strauch, R Suleiman, M Taiuti, Dj Tedeschi, U Thoma, R Thompson, A Tkabladze, L Todor, C Tur, M Ungaro, Mf Vineyard, Av Vlassov, K Wang, Lb Weinstein, H Weller, Dp Weygand, Cs Whisnant, M Williams, E Wolin, Mh Wood, A Yegneswaran, J Yun, L Zana Jan 2005

Radiative Decays Of The Sigma(0)(1385) And Lambda(1520) Hyperons, S Taylor, Gs Mutchler, G Adams, P Ambrozewicz, E Anciant, M Anghinolfi, B Asavapibhop, G Asryan, G Audit, H Avakian, H Bagdasaryan, Jp Ball, S Barrow, V Batourine, M Battaglieri, K Beard, M Bektasoglu, M Bellis, N Benmouna, Bl Berman, N Bianchi, As Biselli, S Boiarinov, Be Bonner, S Bouchigny, R Bradford, D Branford, Wj Briscoe, Wk Brooks, S Bultmann, Vd Burkert, C Butuceanu, Jr Calarco, Ds Carman, B Carnahan, S Chen, Pl Cole, D Cords, P Corvisiero, D Crabb, H Crannell, Jp Cummings, E De Sanctis, R Devita, Pv Degtyarenko, H Denizli, L Dennis, A Deur, Kv Dharmawardane, C Djalali, Ge Dodge, D Doughty, P Dragovitsch, M Dugger, S Dytman, Op Dzyubak, H Egiyan, Ks Egiyan, L Elouadrhiri, A Empl, P Eugenio, R Fatemi, G Feldman, Rg Fersch, Rj Feuerbach, Ta Forest, H Funsten, M Garcon, G Gavalian, Gp Gilfoyle, Kl Giovanetti, E Golovatch, Cio Gordon, Rw Gothe, Ka Griffioen, M Guidal, M Guillo, N Guler, L Guo, V Gyurjyan, C Hadjidakis, Rs Hakobyan, J Hardie, D Heddle, Fw Hersman, K Hicks, I Hleiqawi, M Holtrop, J Hu, M Huertas, Ce Hyde-Wright, Y Ilieva, Dg Ireland, Mm Ito, D Jenkins, K Joo, Hg Juengst, Jd Kellie, M Khandaker, Ky Kim, K Kim, W Kim, A Klein, Fj Klein, Av Klimenko, M Klusman, M Kossov, V Koubarovski, Lh Kramer, Se Kuhn, J Kuhn, J Lachniet, Jm Laget, J Langheinrich, D Lawrence, T Lee, J Li, Acs Lima, K Livingston, K Lukashin, Jj Manak, C Marchand, S Mcaleer, Jwc Mcnabb, Ba Mecking, Jj Melone, Md Mestayer, Ca Meyer, K Mikhailov, M Mirazita, R Miskimen, V Mokeev, L Morand, Sa Morrow, V Muccifora, J Mueller, J Napolitano, R Nasseripour, S Niccolai, G Niculescu, I Niculescu, Bb Niczyporuk, Ra Niyazov, M Nozar, Gv O'Rielly, M Osipenko, Ai Ostrovidov, K Park, E Pasyuk, Sa Philips, N Pivnyuk, D Pocanic, O Pogorelko, E Polli, S Pozdniakov, Bm Preedom, Jw Price, Y Prok, D Protopopescu, Lm Qin, Bs Raue, G Riccardi, G Ricco, M Ripani, Bg Ritchie, F Ronchetti, G Rosner, P Rossi, D Rowntree, Pd Rubin, F Sabatie, C Salgado, Jp Santoro, V Sapunenko, Ra Schumacher, Vs Serov, A Shafi, Yg Sharabian, J Shaw, S Simionatto, Av Skabelin, Es Smith, Lc Smith, Di Sober, M Spraker, A Stavinsky, S Stepanyan, Ss Stepanyan, Be Stokes, P Stoler, Ii Strakovsky, S Strauch, R Suleiman, M Taiuti, Dj Tedeschi, U Thoma, R Thompson, A Tkabladze, L Todor, C Tur, M Ungaro, Mf Vineyard, Av Vlassov, K Wang, Lb Weinstein, H Weller, Dp Weygand, Cs Whisnant, M Williams, E Wolin, Mh Wood, A Yegneswaran, J Yun, L Zana

Michael Williams

The electromagnetic decays of the Sig0(1385) and Lambda(1520) hyperons were studied in photon-induced reactions gamma p -> K+ Lambda(1116)gamma in the CLAS detector at the Thomas Jefferson National Accelerator Facility. We report the first observation of the radiative decay of the Sig0(1385) and a measurement of the Lambda(1520) radiative decay width. For the Sig0(1385) -> Lambda(1116)gamma transition, we measured a partial width of 479+/-120(stat)+81-100(sys) keV, larger than all of the existing model predictions. For the Lambda(1520) -> Lambda(1116)gamma transition, we obtained a partial width of 167+/-43(stat)+26-12(sys) keV.

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Measurement Of The Polarized Structure Function Sigma(Lt ') For Pion Electroproduction In The Roper-Resonance Region, K Joo, Lc Smith, Ig Aznauryan, Vd Burkert, H Egiyan, R Minehart, G Adams, P Ambrozewicz, E Anciant, M Anghinolfi, B Asavapibhop, G Asryan, G Audit, T Auger, H Avakian, H Bagdasaryan, N Baillie, Jp Ball, Na Baltzell, S Barrow, V Batourine, M Battaglieri, K Beard, I Bedlinskiy, M Bektasoglu, M Bellis, N Benmouna, Bl Berman, N Bianchi, As Biselli, Be Bonner, S Bouchigny, S Boiarinov, R Bradford, D Branford, Wj Briscoe, Wk Brooks, S Bueltmann, C Butuceanu, Jr Calarco, Sl Careccia, Ds Carman, B Carnahan, C Cetina, S Chen, Pl Cole, A Coleman, P Coltharp, D Cords, P Corvisiero, D Crabb, Jp Cummings, E De Sanctis, R Devita, Pv Degtyarenko, L Dennis, A Deur, Kv Dharmawardane, Ks Dhuga, C Djalali, Ge Dodge, J Donnelly, D Doughty, P Dragovitsch, M Dugger, S Dytman, Op Dzyubak, Ks Egiyan, L Elouadrhiri, A Empl, P Eugenio, L Farhi, R Fatemi, G Fedotov, G Feldman, Rj Feuerbach, Ta Forest, V Frolov, H Funsten, Sj Gaff, M Garcon, G Gavalian, Gp Gilfoyle, Kl Giovanetti, P Girard, Fx Girod, Jt Goetz, Rw Gothe, Ka Griffioen, M Guidal, M Guillo, N Guler, L Guo, V Gyurjyan, Rs Hakobyan, J Hardie, D Heddle, Fw Hersman, K Hicks, I Hleiqawi, M Holtrop, J Hu, Ce Hyde-Wright, Y Ilieva, Dg Ireland, Bs Ishkhanov, Mm Ito, D Jenkins, Hs Jo, Hg Juengst, Jh Kelley, Jd Kellie, M Khandaker, Ky Kim, K Kim, W Kim, A Klein, Fj Klein, Av Klimenko, M Klusman, M Kossov, Lh Kramer, V Kubarovsky, J Kuhn, Se Kuhn, J Lachniet, Jm Laget, J Langheinrich, D Lawrence, T Lee, K Livingston, K Lukashin, Jj Manak, C Marchand, Lc Maximon, S Mcaleer, B Mckinnon, Jwc Mcnabb, Ba Mecking, Md Mestayer, Ca Meyer, K Mikhailov, M Mirazita, R Miskimen, V Mokeev, Sa Morrow, V Muccifora, J Mueller, Gs Mutchler, P Nadel-Turonski, J Napolitano, R Nasseripour, So Nelson, S Niccolai, G Niculescu, I Niculescu, Bb Niczyporuk, Ra Niyazov, M Nozar, Gv O'Rielly, M Osipenko, Ai Ostrovidov, K Park, E Pasyuk, G Peterson, Sa Philips, J Pierce, N Pivnyuk, D Pocanic, O Pogorelko, E Polli, S Pozdniakov, Bm Preedom, Jw Price, Y Prok, D Protopopescu, Lm Qin, Ba Raue, G Riccardi, G Ricco, M Ripani, Bg Ritchie, F Ronchetti, G Rosner, P Rossi, D Rowntree, Pd Rubin, F Sabatie, K Sabourov, C Salgado, Jp Santoro, V Sapunenko, Ra Schumacher, Vs Serov, A Shafi, Yg Sharabian, J Shaw, S Simionatto, Av Skabelin, Es Smith, Di Sober, M Spraker, A Stavinsky, Ss Stepanyan, S Stepanyan, Be Stokes, P Stoler, Ii Strakovsky, S Strauch, M Taiuti, S Taylor, Dj Tedeschi, U Thoma, R Thompson, A Tkabladze, C Tur, M Ungaro, Mf Vineyard, Av Vlassov, K Wang, Lb Weinstein, H Weller, Dp Weygand, M Williams, E Wolin, Mh Wood, A Yegneswaran, J Yun, L Zana, J Zhang Jan 2005

Measurement Of The Polarized Structure Function Sigma(Lt ') For Pion Electroproduction In The Roper-Resonance Region, K Joo, Lc Smith, Ig Aznauryan, Vd Burkert, H Egiyan, R Minehart, G Adams, P Ambrozewicz, E Anciant, M Anghinolfi, B Asavapibhop, G Asryan, G Audit, T Auger, H Avakian, H Bagdasaryan, N Baillie, Jp Ball, Na Baltzell, S Barrow, V Batourine, M Battaglieri, K Beard, I Bedlinskiy, M Bektasoglu, M Bellis, N Benmouna, Bl Berman, N Bianchi, As Biselli, Be Bonner, S Bouchigny, S Boiarinov, R Bradford, D Branford, Wj Briscoe, Wk Brooks, S Bueltmann, C Butuceanu, Jr Calarco, Sl Careccia, Ds Carman, B Carnahan, C Cetina, S Chen, Pl Cole, A Coleman, P Coltharp, D Cords, P Corvisiero, D Crabb, Jp Cummings, E De Sanctis, R Devita, Pv Degtyarenko, L Dennis, A Deur, Kv Dharmawardane, Ks Dhuga, C Djalali, Ge Dodge, J Donnelly, D Doughty, P Dragovitsch, M Dugger, S Dytman, Op Dzyubak, Ks Egiyan, L Elouadrhiri, A Empl, P Eugenio, L Farhi, R Fatemi, G Fedotov, G Feldman, Rj Feuerbach, Ta Forest, V Frolov, H Funsten, Sj Gaff, M Garcon, G Gavalian, Gp Gilfoyle, Kl Giovanetti, P Girard, Fx Girod, Jt Goetz, Rw Gothe, Ka Griffioen, M Guidal, M Guillo, N Guler, L Guo, V Gyurjyan, Rs Hakobyan, J Hardie, D Heddle, Fw Hersman, K Hicks, I Hleiqawi, M Holtrop, J Hu, Ce Hyde-Wright, Y Ilieva, Dg Ireland, Bs Ishkhanov, Mm Ito, D Jenkins, Hs Jo, Hg Juengst, Jh Kelley, Jd Kellie, M Khandaker, Ky Kim, K Kim, W Kim, A Klein, Fj Klein, Av Klimenko, M Klusman, M Kossov, Lh Kramer, V Kubarovsky, J Kuhn, Se Kuhn, J Lachniet, Jm Laget, J Langheinrich, D Lawrence, T Lee, K Livingston, K Lukashin, Jj Manak, C Marchand, Lc Maximon, S Mcaleer, B Mckinnon, Jwc Mcnabb, Ba Mecking, Md Mestayer, Ca Meyer, K Mikhailov, M Mirazita, R Miskimen, V Mokeev, Sa Morrow, V Muccifora, J Mueller, Gs Mutchler, P Nadel-Turonski, J Napolitano, R Nasseripour, So Nelson, S Niccolai, G Niculescu, I Niculescu, Bb Niczyporuk, Ra Niyazov, M Nozar, Gv O'Rielly, M Osipenko, Ai Ostrovidov, K Park, E Pasyuk, G Peterson, Sa Philips, J Pierce, N Pivnyuk, D Pocanic, O Pogorelko, E Polli, S Pozdniakov, Bm Preedom, Jw Price, Y Prok, D Protopopescu, Lm Qin, Ba Raue, G Riccardi, G Ricco, M Ripani, Bg Ritchie, F Ronchetti, G Rosner, P Rossi, D Rowntree, Pd Rubin, F Sabatie, K Sabourov, C Salgado, Jp Santoro, V Sapunenko, Ra Schumacher, Vs Serov, A Shafi, Yg Sharabian, J Shaw, S Simionatto, Av Skabelin, Es Smith, Di Sober, M Spraker, A Stavinsky, Ss Stepanyan, S Stepanyan, Be Stokes, P Stoler, Ii Strakovsky, S Strauch, M Taiuti, S Taylor, Dj Tedeschi, U Thoma, R Thompson, A Tkabladze, C Tur, M Ungaro, Mf Vineyard, Av Vlassov, K Wang, Lb Weinstein, H Weller, Dp Weygand, M Williams, E Wolin, Mh Wood, A Yegneswaran, J Yun, L Zana, J Zhang

Michael Williams

The polarized longitudinal-transverse structure function σLT' measures the interference between real and imaginary amplitudes in pion electroproduction and can be used to probe the coupling between resonant and nonresonant processes. We report new measurements of σLT' in the N(1440)1/2+ (Roper) resonance region at Q2=0.40 and 0.65GeV2 for both the π0p and π+n channels. The experiment was performed at Jefferson Lab with the CEBAF Large Acceptance Spectrometer (CLAS) using longitudinally polarized electrons at a beam energy of 1.515 GeV. Complete angular distributions were obtained and are compared to recent phenomenological models. The σLT'(π+n) channel shows a large sensitivity to the Roper-resonance …

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Beam-Helicity Asymmetries In Double-Charged-Pion Photoproduction On The Proton, S Strauch, Bl Berman, G Adams, P Ambrozewicz, M Anghinolfi, B Asavapibhop, G Asryan, G Audit, H Avakian, H Bagdasaryan, N Baillie, Jp Ball, Na Baltzell, S Barrow, V Batourine, M Battaglieri, K Beard, I Bedlinskiy, M Bektasoglu, M Bellis, N Benmouna, C Bennhold, As Biselli, S Boiarinov, S Bouchigny, R Bradford, D Branford, Wj Briscoe, Wk Brooks, S Bultmann, Vd Burkert, C Butuceanu, Jr Calarco, Sl Careccia, Ds Carman, B Carnahan, S Chen, Pl Cole, A Coleman, P Coltharp, D Cords, P Corvisiero, D Crabb, H Crannell, Jp Cummings, Pv Degtyarenko, H Denizli, L Dennis, E De Sanctis, A Deur, R Devita, Kv Dharmawardane, Ks Dhuga, C Djalali, Ge Dodge, J Donnelly, D Doughty, P Dragovitsch, M Dugger, S Dytman, Op Dzyubak, H Egiyan, Ks Egiyan, L Elouadrhiri, A Empl, P Eugenio, R Fatemi, G Fedotov, G Feldman, Rj Feuerbach, A Fix, Ta Forest, H Funsten, G Gavalian, Gp Gilfoyle, Kl Giovanetti, Fx Girod, Jt Goetz, Rw Gothe, Ka Griffioen, M Guidal, N Guler, L Guo, V Gyurjyan, C Hadjidakis, Rs Hakobyan, J Hardie, D Heddle, Fw Hersman, K Hicks, I Hleiqawi, M Holtrop, J Hu, M Huertas, Ce Hyde-Wright, Y Ilieva, Dg Ireland, Bs Ishkhanov, Mm Ito, D Jenkins, Hs Jo, K Joo, Hg Juengst, Jd Kellie, M Khandaker, Ky Kim, K Kim, W Kim, A Klein, Fj Klein, Av Klimenko, M Klusman, M Kossov, Lh Kramer, V Kubarovsky, J Kuhn, Se Kuhn, J Lachniet, Jm Laget, J Langheinrich, D Lawrence, T Lee, Acs Lima, K Livingston, K Lukashin, Jj Manak, C Marchand, S Mcaleer, B Mckinnon, Jwc Mcnabb, Ba Mecking, Md Mestayer, Ca Meyer, T Mibe, K Mikhailov, R Minehart, M Mirazita, R Miskimen, V Mokeev, Sa Morrow, V Muccifora, J Mueller, Gs Mutchler, P Nadel-Turonski, J Napolitano, R Nasseripour, S Niccolai, G Niculescu, I Niculescu, Bb Niczyporuk, Ra Niyazov, M Nozar, Gv O'Rielly, M Osipenko, Ai Ostrovidov, K Park, E Pasyuk, C Paterson, Sa Philips, J Pierce, N Pivnyuk, D Pocanic, O Pogorelko, E Polli, S Pozdniakov, Bm Preedom, Jw Price, Y Prok, D Protopopescu, Lm Qin, Ba Raue, G Riccardi, G Ricco, M Ripani, Bg Ritchie, W Roberts, F Ronchetti, G Rosner, P Rossi, D Rowntree, Pd Rubin, F Sabatie, C Salgado, Jp Santoro, V Sapunenko, Ra Schumacher, Vs Serov, A Shafi, Yg Sharabian, J Shaw, Av Skabelin, Es Smith, Lc Smith, Di Sober, A Stavinsky, Ss Stepanyan, S Stepanyan, Be Stokes, P Stoler, Ii Strakovsky, R Suleiman, M Taiuti, S Taylor, Dj Tedeschi, U Thoma, R Thompson, A Tkabladze, S Tkachenko, L Todor, C Tur, M Ungaro, Mf Vineyard, Av Vlassov, K Wang, Lb Weinstein, Dp Weygand, M Williams, E Wolin, Mh Wood, A Yegneswaran, J Yun, L Zana, J Zhang Jan 2005

Beam-Helicity Asymmetries In Double-Charged-Pion Photoproduction On The Proton, S Strauch, Bl Berman, G Adams, P Ambrozewicz, M Anghinolfi, B Asavapibhop, G Asryan, G Audit, H Avakian, H Bagdasaryan, N Baillie, Jp Ball, Na Baltzell, S Barrow, V Batourine, M Battaglieri, K Beard, I Bedlinskiy, M Bektasoglu, M Bellis, N Benmouna, C Bennhold, As Biselli, S Boiarinov, S Bouchigny, R Bradford, D Branford, Wj Briscoe, Wk Brooks, S Bultmann, Vd Burkert, C Butuceanu, Jr Calarco, Sl Careccia, Ds Carman, B Carnahan, S Chen, Pl Cole, A Coleman, P Coltharp, D Cords, P Corvisiero, D Crabb, H Crannell, Jp Cummings, Pv Degtyarenko, H Denizli, L Dennis, E De Sanctis, A Deur, R Devita, Kv Dharmawardane, Ks Dhuga, C Djalali, Ge Dodge, J Donnelly, D Doughty, P Dragovitsch, M Dugger, S Dytman, Op Dzyubak, H Egiyan, Ks Egiyan, L Elouadrhiri, A Empl, P Eugenio, R Fatemi, G Fedotov, G Feldman, Rj Feuerbach, A Fix, Ta Forest, H Funsten, G Gavalian, Gp Gilfoyle, Kl Giovanetti, Fx Girod, Jt Goetz, Rw Gothe, Ka Griffioen, M Guidal, N Guler, L Guo, V Gyurjyan, C Hadjidakis, Rs Hakobyan, J Hardie, D Heddle, Fw Hersman, K Hicks, I Hleiqawi, M Holtrop, J Hu, M Huertas, Ce Hyde-Wright, Y Ilieva, Dg Ireland, Bs Ishkhanov, Mm Ito, D Jenkins, Hs Jo, K Joo, Hg Juengst, Jd Kellie, M Khandaker, Ky Kim, K Kim, W Kim, A Klein, Fj Klein, Av Klimenko, M Klusman, M Kossov, Lh Kramer, V Kubarovsky, J Kuhn, Se Kuhn, J Lachniet, Jm Laget, J Langheinrich, D Lawrence, T Lee, Acs Lima, K Livingston, K Lukashin, Jj Manak, C Marchand, S Mcaleer, B Mckinnon, Jwc Mcnabb, Ba Mecking, Md Mestayer, Ca Meyer, T Mibe, K Mikhailov, R Minehart, M Mirazita, R Miskimen, V Mokeev, Sa Morrow, V Muccifora, J Mueller, Gs Mutchler, P Nadel-Turonski, J Napolitano, R Nasseripour, S Niccolai, G Niculescu, I Niculescu, Bb Niczyporuk, Ra Niyazov, M Nozar, Gv O'Rielly, M Osipenko, Ai Ostrovidov, K Park, E Pasyuk, C Paterson, Sa Philips, J Pierce, N Pivnyuk, D Pocanic, O Pogorelko, E Polli, S Pozdniakov, Bm Preedom, Jw Price, Y Prok, D Protopopescu, Lm Qin, Ba Raue, G Riccardi, G Ricco, M Ripani, Bg Ritchie, W Roberts, F Ronchetti, G Rosner, P Rossi, D Rowntree, Pd Rubin, F Sabatie, C Salgado, Jp Santoro, V Sapunenko, Ra Schumacher, Vs Serov, A Shafi, Yg Sharabian, J Shaw, Av Skabelin, Es Smith, Lc Smith, Di Sober, A Stavinsky, Ss Stepanyan, S Stepanyan, Be Stokes, P Stoler, Ii Strakovsky, R Suleiman, M Taiuti, S Taylor, Dj Tedeschi, U Thoma, R Thompson, A Tkabladze, S Tkachenko, L Todor, C Tur, M Ungaro, Mf Vineyard, Av Vlassov, K Wang, Lb Weinstein, Dp Weygand, M Williams, E Wolin, Mh Wood, A Yegneswaran, J Yun, L Zana, J Zhang

Michael Williams

Beam-helicity asymmetries for the two-pion-photoproduction reaction γ⃗p→pπ+π- have been studied for the first time in the resonance region for center-of-mass energies between 1.35 and 2.30 GeV. The experiment was performed at Jefferson Lab with the CEBAF Large Acceptance Spectrometer using circularly polarized tagged photons incident on an unpolarized hydrogen target. Beam-helicity-dependent angular distributions of the final-state particles were measured. The large cross-section asymmetries exhibit strong sensitivity to the kinematics and dynamics of the reaction. The data are compared with the results of various phenomenological model calculations, and show that these models currently do not provide an adequate description for the …

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Vibrational Dependence Of The H2–H2 C6 Coefficients, Robert Hinde Jan 2005

Vibrational Dependence Of The H2–H2 C6 Coefficients, Robert Hinde

Robert Hinde

We use the sum-over-states formalism to compute the imaginary-frequency dipole polarizabilities for H2, as a function of the H–H bond length, at the full configuration interaction level of theory using atom-centered d-aug-cc-pVQZ basis sets. From these polarizabilities, we obtain isotropic and anisotropic C6 dispersion coefficients for a pair of H2 molecules as functions of the two molecules’ bond lengths.

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Measurement Of Cp Asymmetries In B0 --> KS0∏0∏0, B. Aubert, Stefan Spanier Jan 2005

Measurement Of Cp Asymmetries In B0 --> KS0∏0∏0, B. Aubert, Stefan Spanier

stefan spanier

We present a preliminary measurement of the time-dependent CP asymmetry for the neutral B-meson decay into the CP = +1 final state K0 Sπ0π0, with K0 S → π+π− and π0 → γγ. We use a sample of approximately 227 million B-meson pairs recorded at the Υ(4S) resonance by the BABAR detector at the PEP-II B-Factory at SLAC. From a maximum likelihood fit we extract the mixing-induced CP-violation parameter SK0 Sπ0π0 = 0.84 ± 0.71 (stat) ± 0.08 (syst) and the direct CP-violation parameter CK0 Sπ0π0 = 0.27 ± 0.52 (stat) ± 0.13 (syst), where the first uncertainty is statistical …

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Measurement Of Cp Asymmetries In B0 --> {Eff}K0 And B0 --> K+K-K0S Decays, B. Aubert, Stefan Spanier Jan 2005

Measurement Of Cp Asymmetries In B0 --> {Eff}K0 And B0 --> K+K-K0S Decays, B. Aubert, Stefan Spanier

stefan spanier

We measure the time-dependent CP asymmetry parameters in B0 --> K+ K- K0 based on a data sample of approximately 227 million B-meson pairs recorded at the Upsilon(4S) resonance with the BaBar detector at the PEP-II B-meson Factory at SLAC. We reconstruct two-body B0 decays to Phi(1020) K0S and Phi(1020)K0L, and the three-body decay K+ K- K0S with Phi(1020) K0S excluded. For the B0 --> Phi K0 decays, we measure sin(2 beta_{eff})(Phi K0) = +0.50 +/- 0.25(stat) +0.07/-0.04(syst). The B0 --> K+ K- K0S decays are dominated by K+ K- S-wave, as determined from an angular analysis; we measure sin(2 …

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Momentum Balance Diagnoses For The West Florida Shelf, Yonggang Liu, Robert H. Weisberg Jan 2005

Momentum Balance Diagnoses For The West Florida Shelf, Yonggang Liu, Robert H. Weisberg

Yonggang Liu

The momentum balance over the West Florida Shelf is diagnosed using observations of currents, bottom pressures, temperatures, winds, and coastal sea levels, along with hydrographic data from 32 monthly cruises spanning summer 1998 to winter 2001. Over synoptic weather time scales, the depth-averaged across-shelf momentum balance on the inner shelf is essentially geostrophic with smaller contributions from the across-shelf wind stress and other terms. Coherence analyses show that 95% of the acceleration (Coriolis and local) variance may be accounted for by the pressure gradient and friction (surface and bottom) over the synoptic weather band. The balances are more complicated on …

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A Conditional Model Of Deduplication For Multi-Type Relational Data, Aron Culotta, Andrew Mccallum Jan 2005

A Conditional Model Of Deduplication For Multi-Type Relational Data, Aron Culotta, Andrew Mccallum

Andrew McCallum

Record deduplication is the task of merging database records that refer to the same underlying entity. In relational databases, accurate deduplication for records of one type is often dependent on the merge decisions made for records of other types. Whereas nearly all previous approaches have merged records of different types independently, this work models these inter-dependencies explicitly to collectively deduplicate records of multiple types. We construct a conditional random field model of deduplication that captures these relational dependencies, and then employ a novel relational partitioning algorithm to jointly deduplicate records. We evaluate the system on two citation matching datasets, for …

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Group And Topic Discovery From Relations And Text, Xuerui Wang, Natasha Mohanty, Andrew Mccallum Jan 2005

Group And Topic Discovery From Relations And Text, Xuerui Wang, Natasha Mohanty, Andrew Mccallum

Andrew McCallum

We present a probabilistic generative model of entity relationships and textual attributes that simultaneously discovers groups among the entities and topics among the corresponding text. Block-models of relationship data have been studied in social network analysis for some time. Here we simultaneously cluster in several modalities at once, incorporating the words associated with certain relationships. Significantly, joint inference allows the discovery of groups to be guided by the emerging topics, and vice-versa. We present experimental results on two large data sets: sixteen years of bills put before the U.S. Senate, comprising their corresponding text and voting records, and 43 years …

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Multi-Way Distributional Clustering Via Pairwise Interactions, Ron Bekkerman, Ran El-Yaniv, Andrew Mccallum Jan 2005

Multi-Way Distributional Clustering Via Pairwise Interactions, Ron Bekkerman, Ran El-Yaniv, Andrew Mccallum

Andrew McCallum

We present a novel unsupervised learning scheme that simultaneously clusters variables of several types (e.g., documents, words and authors) based on pairwise interactions between the types, as observed in co-occurrence data. In this scheme, multiple clustering systems are generated aiming at maximizing an objective function that measures multiple pairwise mutual information between cluster variables. To implement this idea, we propose an algorithm that interleaves top-down clustering of some variables and bottom-up clustering of the other variables, with a local optimization correction routine. Focusing on document clustering we present an extensive empirical study of two-way, three-way and four-way applications of our …

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A Note On Topical N-Grams, Xuerui Wang, Andrew Mccallum Jan 2005

A Note On Topical N-Grams, Xuerui Wang, Andrew Mccallum

Andrew McCallum

Most of the popular topic models (such as Latent Dirichlet Allocation) have an underlying assumption: bag of words. However, text is indeed a sequence of discrete word tokens, and without considering the order of words (in another word, the nearby context where a word is located), the accurate meaning of language cannot be exactly captured by word co-occurrences only. In this sense, collocations of words (phrases) have to be considered. However, like individual words, phrases sometimes show polysemy as well depending on the context. More noticeably, a composition of two (or more) words is a phrase in some context, but …

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Automatic Categorization Of Email Into Folders: Benchmark Experiments On Enron And Sri Corpora, Ron Bekkerman, Andrew Mccallum, Gary Huang Jan 2005

Automatic Categorization Of Email Into Folders: Benchmark Experiments On Enron And Sri Corpora, Ron Bekkerman, Andrew Mccallum, Gary Huang

Andrew McCallum

Office workers everywhere are drowning in email---not only spam, but also large quantities of legitimate email to be read and organized for browsing. Although there have been extensive investigations of automatic document categorization, email gives rise to a number of unique challenges, and there has been relatively little study of classifying email into folders. This paper presents an extensive benchmark study of email foldering using two large corpora of real-world email messages and foldering schemes: one from former Enron employees, another from participants in an SRI research project. We discuss the challenges that arise from differences between email foldering and …

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Composition Of Conditional Random Fields For Transfer Learning, Charles Sutton, Andrew Mccallum Jan 2005

Composition Of Conditional Random Fields For Transfer Learning, Charles Sutton, Andrew Mccallum

Andrew McCallum

Many learning tasks have subtasks for much training data exists. Therefore, we want to transfer learning from the old, general-purpose subtask to a more specific new task, for which there is often less data. While work in transfer learning often considers how the old task should affect learning on the new task, in this paper we show that it helps to take into account how the new task affects the old. Specifically, we perform joint decoding of separately-trained sequence models, preserving uncertainty between the tasks and allowing information from the new task to affect predictions on the old task. On …

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Feature Bagging: Preventing Weight Undertraining In Structured Discriminative Learning, Charles Sutton, Michael Sindelar, Andrew Mccallum Jan 2005

Feature Bagging: Preventing Weight Undertraining In Structured Discriminative Learning, Charles Sutton, Michael Sindelar, Andrew Mccallum

Andrew McCallum

Discriminatively-trained probabilistic models are widely useful because of the latitude they afford in designing features. But training involves complex trade-offs among weights, which can be dangerous: a few highly-indicative features can swamp the contribution of many individually weaker features, causing their weights to be undertrained. Such a model is less robust, for the highly-indicative features may be noisy or missing in the test data. To ameliorate this \emph{weight undertraining}, we propose a new training method, called \emph{feature bagging}, in which separate models are trained on subsets of the original features, and combined using a mixture model or a product of …

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Sparse Forward-Backward For Fast Training Of Conditional Random Fields, Charles Sutton, Chris Pal, Andrew Mccallum Jan 2005

Sparse Forward-Backward For Fast Training Of Conditional Random Fields, Charles Sutton, Chris Pal, Andrew Mccallum

Andrew McCallum

Complex tasks in speech and language processing often include random variables with large state spaces, both in speech tasks that involve predicting words and phonemes, and in joint processing of pipelined systems, in which the state space can be the labeling of an entire sequence. In large state spaces, however, discriminative training can be expensive, because it often requires many calls to forward-backward. Beam search is a standard heuristic for controlling complexity during Viterbi decoding, but during forward-backward, standard beam heuristics can be dangerous, as they can make training unstable. We introduce sparse forward-backward, a variational perspective on beam methods …

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Direct Maximization Of Rank-Based Metrics For Information Retrieval, Donald A. Metzler, W. Bruce Croft, Andrew Mccallum Jan 2005

Direct Maximization Of Rank-Based Metrics For Information Retrieval, Donald A. Metzler, W. Bruce Croft, Andrew Mccallum

Andrew McCallum

Ranking is an essential component for a number of tasks, such as information retrieval and collaborative filtering. It is often the case that the underlying task attempts to maximize some evaluation metric, such as mean average precision, over rankings. Most past work on learning how to rank has focused on likelihood- or margin-based approaches. In this work we explore directly maximizing rank-based metrics, which are a family of metrics that only depend on the order of ranked items. This allows us to maximize different metrics for the same training data. We show how the parameter space of linear scoring functions …

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Reducing Labeling Effort For Structured Prediction Tasks, Aron Culotta, Andrew Mccallum Jan 2005

Reducing Labeling Effort For Structured Prediction Tasks, Aron Culotta, Andrew Mccallum

Andrew McCallum

A common obstacle preventing the rapid deployment of supervised machine learning algorithms is the lack of labeled training data. This is particularly expensive to obtain for structured prediction tasks, where each training instance may have multiple, interacting labels, all of which must be correctly annotated for the instance to be of use to the learner. Traditional active learning addresses this problem by optimizing the order in which the examples are labeled to increase learning efficiency. However, this approach does not consider the difficulty of labeling each example, which can vary widely in structured prediction tasks. For example, the labeling predicted …

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Land Planning And Development Mitigation For Protecting Water Quality In The Great Lakes System: An Evaluation Of Us Approaches, Elizabeth Brabec, Peter Kumble Jan 2005

Land Planning And Development Mitigation For Protecting Water Quality In The Great Lakes System: An Evaluation Of Us Approaches, Elizabeth Brabec, Peter Kumble

Elizabeth Brabec

Since 1978, studies by the International Joint Commission (the bi-national commission mandated to protect the Great Lakes) have shown increasing water quality stress due to urban non-point source pollution. The key question for the IJC today, as an international commission with no direct enforcement power, is how the IJC can be effective in getting the parties and their jurisdictions to improve management of non-point source pollution issues when the land use trigger is primarily a local government issue. To begin to answer this question, the primary objective of this current study is to assemble the latest data and analysis on …

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Erratum: “Uniqueness Theorems In Bioluminescence Tomography” [Med. Phys. 31, 2289–2299 (2004)], Ge Wang, Yi Li, Ming Jiang Jan 2005

Erratum: “Uniqueness Theorems In Bioluminescence Tomography” [Med. Phys. 31, 2289–2299 (2004)], Ge Wang, Yi Li, Ming Jiang

Yi Li

In this Erratum, we present a correction to our proof of Theorem D.4 in Ref. 1.

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Joint Parsing And Semantic Role Labeling, Charles Sutton, Andrew Mccallum Jan 2005

Joint Parsing And Semantic Role Labeling, Charles Sutton, Andrew Mccallum

Andrew McCallum

A striking feature of human syntactic processing is that it is context-dependent, that is, it seems to take into account semantic information from the discourse context and world knowledge. In this paper, we attempt to use this insight to bridge the gap between SRL results from gold parses and from automatically-generated parses. To do this, we jointly perform parsing and semantic role labeling, using a probabilistic SRL system to rerank the results of a probabilistic parser. Our current results are negative, because a locally-trained SRL model can return inaccurate probability estimates.

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Gene Prediction With Conditional Random Fields, Aron Culotta, David Kulp, Andrew Mccallum Jan 2005

Gene Prediction With Conditional Random Fields, Aron Culotta, David Kulp, Andrew Mccallum

Andrew McCallum

Given a sequence of DNA nucleotide bases, the task of gene prediction is to find subsequences of bases that encode proteins. Reasonable performance on this task has been achieved using generatively trained sequence models, such as hidden Markov models. We propose instead the use of a discriminitively trained sequence model, the conditional random field (CRF). CRFs can naturally incorporate arbitrary, non-independent features of the input without making conditional independence assumptions among the features. This can be particularly important for gene finding, where including evidence from protein databases, EST data, or tiling arrays may improve accuracy. We evaluate our model on …

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Disambiguating Web Appearances Of People In A Social Network, Ron Bekkerman, Andrew Mccallum Jan 2005

Disambiguating Web Appearances Of People In A Social Network, Ron Bekkerman, Andrew Mccallum

Andrew McCallum

You are looking for information about a particular person. A search engine returns many pages for that person's name, but which pages are about the person you care about, and which are about other people who happen to have the same name? Furthermore, if we are looking for multiple people who are related in some way, how can we best leverage this social network? This paper presents two unsupervised frameworks for solving this problem: one based on link structure of the web pages, another using the recently introduced Bootstrapped Information Bottleneck (BIB) clustering method. To evaluate our methods, we collected …

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Reducing Weight Undertraining In Structured Discriminative Learning, Charles Sutton, Michael Sindelar, Andrew Mccallum Jan 2005

Reducing Weight Undertraining In Structured Discriminative Learning, Charles Sutton, Michael Sindelar, Andrew Mccallum

Andrew McCallum

Discriminative probabilistic models are very popular in NLP because of the latitude they afford in designing features. But training involves complex trade-offs among weights, which can be dangerous: a few highly-indicative features can swamp the contribution of many individually weaker features, causing their weights to be undertrained. Such a model is less robust, for the highly-indicative features may be noisy or missing in the test data. To ameliorate this weight undertraining, we introduce several new feature bagging methods, in which separate models are trained on subsets of the original features, and combined using a mixture model or a product of …

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Fast, Piecewise Training For Discriminative Finite-State And Parsing Models, Charles Sutton, Andrew Mccallum Jan 2005

Fast, Piecewise Training For Discriminative Finite-State And Parsing Models, Charles Sutton, Andrew Mccallum

Andrew McCallum

Discriminitive models for sequences and trees---such as linear-chain conditional random fields (CRFs) and max-margin parsing---have shown great promise because they combine the ability to incorporate arbitrary\comment{ non-independent} input features and the benefits of principled global inference over their structured outputs. However, since parameter estimation in these models involves repeatedly performing this global inference, training can be very slow. We present {\it piecewise training}, a new training method that combines the speed of local training with the accuracy of global training by incorporating a limited amount of global information derived from previous errors of the model. On named-entity and part-of-speech data, …

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Piecewise Training For Undirected Models, Charles Sutton, Andrew Mccallum Jan 2005

Piecewise Training For Undirected Models, Charles Sutton, Andrew Mccallum

Andrew McCallum

For many large undirected models that arise in real-world applications, exact maximumlikelihood training is intractable, because it requires computing marginal distributions of the model. Conditional training is even more difficult, because the partition function depends not only on the parameters, but also on the observed input, requiring repeated inference over each training example. An appealing idea for such models is to independently train a local undirected classifier over each clique, afterwards combining the learned weights into a single global model. In this paper, we show that this piecewise method can be justified as minimizing a new family of upper bounds …

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On The Supersymmetry Group Of The Classical Bose-Fermi Oscillator,", Tilmann Glimm, Rudolf Schmid Jan 2005

On The Supersymmetry Group Of The Classical Bose-Fermi Oscillator,", Tilmann Glimm, Rudolf Schmid

Mathematics Faculty Publications

Applying the concept of a momentum map for supersymplectic supervectorspaces to the one-dimensional Bose-Fermi oscillator, we show that the largest symmetry group that admits a momentum map is the identity component of the intersection of the orthosymplectic group OSp(2|2) and the group of supersymplectic transformations. This gives a systematic characterization of a certain class of odd supersymmetry transformations that were originally introduced in an ad hoc way.

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Connectivity Of Random K-Nearest-Neighbor Graphs, Paul Balister, Béla Bollobás, Amites Sarkar, Mark Walters Jan 2005

Connectivity Of Random K-Nearest-Neighbor Graphs, Paul Balister, Béla Bollobás, Amites Sarkar, Mark Walters

Mathematics Faculty Publications

Let P be a Poisson process of intensity one in a square Sn of area n. We construct a random geometric graph Gn,k by joining each point of Pto its k ≡ k(n) nearest neighbours. Recently, Xue and Kumar proved that if k ≤ 0.074logn then the probability that Gn,k is connected tends to 0 as n → ∞ while, if k ≥ 5.1774logn, then the probability that Gn,k is connected tends to 1 as n → ∞. They conjectured that the …

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Review Of: Newton Methods For Nonlinear Problems: Affine Invariance And Adaptive Algorithms, By P. Deuflhard, Tjalling Ypma Jan 2005

Review Of: Newton Methods For Nonlinear Problems: Affine Invariance And Adaptive Algorithms, By P. Deuflhard, Tjalling Ypma

Mathematics Faculty Publications

In the context of solving nonlinear equations, the term "affine invariance" was introduced to describe the fact that when a function F: Rn → Rn is transformed to G = AF ,where A is an invertible matrix, then the equation F(x) = 0 has the same solutions as G(x) = 0, and the Newton iterates Xk+1 = Xk-F'(Xk)-1F(Xk) remain unchanged when F is replaced by G. The idea was that this property of Newton's method should …

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