Redox conditions and authigenic mineralization related to cold seeps in central Guaymas Basin, Gulf of California

Authigenic carbonate crusts, surface muds and bivalve shell fragments have been recovered from inactive and active recently discovered cold seep sites in central Guaymas Basin. In this study, for first time, redox conditions and fluid sources involved in mineral precipitation were investigated by analyzing the mineralogy and textures of surface samples, along with skeletal contents, and C, O and S isotopes variations. The d13C values of aragonitic bivalve shells and non-skeletal carbonate from some surface muds (1‰ to -3.7‰ V-PDB) suggest that carbonate precipitated from ambient dissolved inorganic carbon, whereas fibrous aragonite cement and non-skeletal carbonate from other sites are highly depleted in 13C (down to -47.6‰ V-PDB), suggesting formation via anaerobic oxidation of methane, characteristic of methane seepage environments. d18O in most of the carbonates varies from +1.4‰ to +3.2‰ V-PDB, indicating that they formed from slightly modified seawater. Some non-skeletal carbonate grains from surface muds have lower d18O values (-12.5‰ to -8.2‰ V-PDB) reflecting the influence of 18O-depleted pore water. Size distribution of pyrite framboids (mean value: 3.1¿µm) scattered within diatomaceous sinter suggests formation from anoxic-sulfidic bottom waters. d34S in pyrite is of -0.3‰ V-CDT compared to +46.6‰ V-CDT in barite, thus implying a fluid sulfate-sulfide fractionation of 21.3‰ that argues in favor of microbial sulfate reduction as the processes that mediated pyrite framboid formation, in a semi-closed system. Barite formation occurred through the mixing of reducing and Ba-rich seep fluids with a 34S-enriched sulfate pool that resulted from microbial sulfate reduction in a semi-closed system. The chemical composition of aragonite cement, barite and pyrite suggest mineral precipitation from modified seawater. Taken together, our data suggest that mineralization at the studied seep sites is controlled by the mixing of seawater with minor amounts of hydrothermal fluids, and oxygen-depleted conditions favoring anaerobic microbial processes.Peer ReviewedPostprint (author's final draft

Clinical features, diagnosis, and survival analysis of dogs with glioma

Background: Gliomas in dogs remain poorly understood. Objectives: To characterize the clinicopathologic findings, diagnostic imaging features and survival of a large sample of dogs with glioma using the Comparative Brain Tumor Consortium diagnostic classification. Animals: Ninety-one dogs with histopathological diagnosis of glioma. Methods: Multicentric retrospective case series. Signalment, clinicopathologic findings, diagnostic imaging characteristics, treatment, and outcome were used. Tumors were reclassified according to the new canine glioma diagnostic scheme. Results: No associations were found between clinicopathologic findings or survival and tumor type or grade. However, definitive treatments provided significantly (P = .03) improved median survival time (84 days; 95% confidence interval [CI], 45-190) compared to palliative treatment (26 days; 95% CI, 11-54). On magnetic resonance imaging (MRI), oligodendrogliomas were associated with smooth margins and T1-weighted hypointensity compared to astrocytomas (odds ratio [OR], 42.5; 95% CI, 2.42-744.97; P = .04; OR, 45.5; 95% CI, 5.78-333.33; P < .001, respectively) and undefined gliomas (OR, 84; 95% CI, 3.43-999.99; P = .02; OR, 32.3; 95% CI, 2.51-500.00; P = .008, respectively) and were more commonly in contact with the ventricles than astrocytomas (OR, 7.47; 95% CI, 1.03-53.95; P = .049). Tumor spread to neighboring brain structures was associated with high-grade glioma (OR, 6.02; 95% CI, 1.06-34.48; P = .04). Conclusions and Clinical Importance: Dogs with gliomas have poor outcomes, but risk factors identified in survival analysis inform prognosis and the newly identified MRI characteristics could refine diagnosis of tumor type and grade

Arabidopsis COGWHEEL1 links light perception and gibberellins with seed tolerance to deterioration

[ES] Significance Statement Seed tolerance to deterioration depends on anti-aging defenses only partially understood. COG1 encodes a transcription factor previously described to attenuate phytochrome responses to light and we found that it is a positive regulator of seed tolerance to deterioration while light perception by phytochromes is negative. The proposed mechanism is that COG1 increases gibberellins levels, leading to a seed coat containing more suberin and less permeable to oxygen. Light is known to inhibit gibberellins action.This work was supported by grant BIO2014-52621-R from the Spanish 'Ministerio de Economia y Competitividad', Madrid. We thank the 'Servicio de Cuantificacion de Hormonas Vegetales' of our institute for the determination of GA, ABA and auxin.Bueso Ródenas, E.; Muñoz Bertomeu, J.; Campos, F.; Martínez-Ortuño, CJ.; Tello Lacal, C.; Martínez-Almonacid, I.; Ballester Fuentes, P.... (2016). Arabidopsis COGWHEEL1 links light perception and gibberellins with seed tolerance to deterioration. The Plant Journal. 87(6):583-596. https://doi.org/10.1111/tpj.13220S583596876Albert, S., Delseny, M., & Devic, M. (1997). BANYULS, a novel negative regulator of flavonoid biosynthesis in the Arabidopsis seed coat. The Plant Journal, 11(2), 289-299. doi:10.1046/j.1365-313x.1997.11020289.xAlejandro, S., Rodríguez, P. L., Bellés, J. M., Yenush, L., García-Sanchez, M. J., Fernández, J. A., & Serrano, R. (2007). An Arabidopsis quiescin-sulfhydryl oxidase regulates cation homeostasis at the root symplast–xylem interface. The EMBO Journal, 26(13), 3203-3215. doi:10.1038/sj.emboj.7601757Arsovski, A. A., Haughn, G. W., & Western, T. L. (2010). Seed coat mucilage cells ofArabidopsis thalianaas a model for plant cell wall research. Plant Signaling & Behavior, 5(7), 796-801. doi:10.4161/psb.5.7.11773Bailly, C. (2004). Active oxygen species and antioxidants in seed biology. Seed Science Research, 14(2), 93-107. doi:10.1079/ssr2004159Beisson, F., Li, Y., Bonaventure, G., Pollard, M., & Ohlrogge, J. B. (2007). The Acyltransferase GPAT5 Is Required for the Synthesis of Suberin in Seed Coat and Root of Arabidopsis. The Plant Cell, 19(1), 351-368. doi:10.1105/tpc.106.048033Bernard, V., Lecharny, A., & Brunaud, V. (2010). Improved detection of motifs with preferential location in promoters. Genome, 53(9), 739-752. doi:10.1139/g10-042Berridge, M. V., Herst, P. M., & Tan, A. S. (2005). Tetrazolium dyes as tools in cell biology: New insights into their cellular reduction. Biotechnology Annual Review, 127-152. doi:10.1016/s1387-2656(05)11004-7BRAYBROOK, S., & HARADA, J. (2008). LECs go crazy in embryo development. Trends in Plant Science, 13(12), 624-630. doi:10.1016/j.tplants.2008.09.008Brazma, A., Hingamp, P., Quackenbush, J., Sherlock, G., Spellman, P., Stoeckert, C., … Vingron, M. (2001). Minimum information about a microarray experiment (MIAME)—toward standards for microarray data. Nature Genetics, 29(4), 365-371. doi:10.1038/ng1201-365Brundrett, M. C., Kendrick, B., & Peterson, C. A. (1991). Efficient Lipid Staining in Plant Material with Sudan Red 7B or Fluoral Yellow 088 in Polyethylene Glycol-Glycerol. Biotechnic & Histochemistry, 66(3), 111-116. doi:10.3109/10520299109110562Bueso, E., Muñoz-Bertomeu, J., Campos, F., Brunaud, V., Martínez, L., Sayas, E., … Serrano, R. (2013). ARABIDOPSIS THALIANA HOMEOBOX25 Uncovers a Role for Gibberellins in Seed Longevity. Plant Physiology, 164(2), 999-1010. doi:10.1104/pp.113.232223Bueso, E., Ibañez, C., Sayas, E., Muñoz-Bertomeu, J., Gonzalez-Guzmán, M., Rodriguez, P. L., & Serrano, R. (2014). A forward genetic approach in Arabidopsis thaliana identifies a RING-type ubiquitin ligase as a novel determinant of seed longevity. Plant Science, 215-216, 110-116. doi:10.1016/j.plantsci.2013.11.004Chandler, J. W., Abrams, S. R., & Bartels, D. (1997). The effect of ABA analogs on callus viability and gene expression in Craterostigma plantagineum. Physiologia Plantarum, 99(3), 465-469. doi:10.1034/j.1399-3054.1997.990315.xChâtelain, E., Satour, P., Laugier, E., Ly Vu, B., Payet, N., Rey, P., & Montrichard, F. (2013). Evidence for participation of the methionine sulfoxide reductase repair system in plant seed longevity. Proceedings of the National Academy of Sciences, 110(9), 3633-3638. doi:10.1073/pnas.1220589110Chen, H., Chu, P., Zhou, Y., Li, Y., Liu, J., Ding, Y., … Huang, S. (2012). Overexpression of AtOGG1, a DNA glycosylase/AP lyase, enhances seed longevity and abiotic stress tolerance in Arabidopsis. Journal of Experimental Botany, 63(11), 4107-4121. doi:10.1093/jxb/ers093Clerkx, E. J. M., Blankestijn-De Vries, H., Ruys, G. J., Groot, S. P. C., & Koornneef, M. (2004). Genetic differences in seed longevity of various Arabidopsis mutants. Physiologia Plantarum, 121(3), 448-461. doi:10.1111/j.0031-9317.2004.00339.xCurtis, M. D., & Grossniklaus, U. (2003). A Gateway Cloning Vector Set for High-Throughput Functional Analysis of Genes in Planta. Plant Physiology, 133(2), 462-469. doi:10.1104/pp.103.027979De Simone, O., Haase, K., Müller, E., Junk, W. J., Hartmann, K., Schreiber, L., & Schmidt, W. (2003). Apoplasmic Barriers and Oxygen Transport Properties of Hypodermal Cell Walls in Roots from Four Amazonian Tree Species. Plant Physiology, 132(1), 206-217. doi:10.1104/pp.102.014902Debeaujon, I., Léon-Kloosterziel, K. M., & Koornneef, M. (2000). Influence of the Testa on Seed Dormancy, Germination, and Longevity in Arabidopsis. Plant Physiology, 122(2), 403-414. doi:10.1104/pp.122.2.403Domergue, F., Vishwanath, S. J., Joubès, J., Ono, J., Lee, J. A., Bourdon, M., … Rowland, O. (2010). Three Arabidopsis Fatty Acyl-Coenzyme A Reductases, FAR1, FAR4, and FAR5, Generate Primary Fatty Alcohols Associated with Suberin Deposition. Plant Physiology, 153(4), 1539-1554. doi:10.1104/pp.110.158238Espley, R. V., Brendolise, C., Chagné, D., Kutty-Amma, S., Green, S., Volz, R., … Allan, A. C. (2009). Multiple Repeats of a Promoter Segment Causes Transcription Factor Autoregulation in Red Apples. The Plant Cell, 21(1), 168-183. doi:10.1105/tpc.108.059329Farrant, J. M., & Moore, J. P. (2011). Programming desiccation-tolerance: from plants to seeds to resurrection plants. Current Opinion in Plant Biology, 14(3), 340-345. doi:10.1016/j.pbi.2011.03.018Fornara, F., Panigrahi, K. C. S., Gissot, L., Sauerbrunn, N., Rühl, M., Jarillo, J. A., & Coupland, G. (2009). Arabidopsis DOF Transcription Factors Act Redundantly to Reduce CONSTANS Expression and Are Essential for a Photoperiodic Flowering Response. Developmental Cell, 17(1), 75-86. doi:10.1016/j.devcel.2009.06.015Gutierrez, L., Van Wuytswinkel, O., Castelain, M., & Bellini, C. (2007). Combined networks regulating seed maturation. Trends in Plant Science, 12(7), 294-300. doi:10.1016/j.tplants.2007.06.003Hajdu, A., Ádám, É., Sheerin, D. J., Dobos, O., Bernula, P., Hiltbrunner, A., … Nagy, F. (2015). High-level expression and phosphorylation of phytochrome B modulates flowering time in Arabidopsis. The Plant Journal, 83(5), 794-805. doi:10.1111/tpj.12926Haughn, G., & Chaudhury, A. (2005). Genetic analysis of seed coat development in Arabidopsis. Trends in Plant Science, 10(10), 472-477. doi:10.1016/j.tplants.2005.08.005He, H., de Souza Vidigal, D., Snoek, L. B., Schnabel, S., Nijveen, H., Hilhorst, H., & Bentsink, L. (2014). Interaction between parental environment and genotype affects plant and seed performance in Arabidopsis. Journal of Experimental Botany, 65(22), 6603-6615. doi:10.1093/jxb/eru378Hedden, P., & Thomas, S. G. (2012). Gibberellin biosynthesis and its regulation. Biochemical Journal, 444(1), 11-25. doi:10.1042/bj20120245Hellens, R., Allan, A., Friel, E., Bolitho, K., Grafton, K., Templeton, M., … Laing, W. (2005). Plant Methods, 1(1), 13. doi:10.1186/1746-4811-1-13Hoekstra, F. A., Golovina, E. A., & Buitink, J. (2001). Mechanisms of plant desiccation tolerance. Trends in Plant Science, 6(9), 431-438. doi:10.1016/s1360-1385(01)02052-0Holdsworth, M., Kurup, S., & MKibbin, R. (1999). Molecular and genetic mechanisms regulating the transition from embryo development to germination. Trends in Plant Science, 4(7), 275-280. doi:10.1016/s1360-1385(99)01429-6Hu, J., Mitchum, M. G., Barnaby, N., Ayele, B. T., Ogawa, M., Nam, E., … Sun, T. (2008). Potential Sites of Bioactive Gibberellin Production during Reproductive Growth in Arabidopsis. The Plant Cell, 20(2), 320-336. doi:10.1105/tpc.107.057752Hudson, M. E., & Quail, P. H. (2003). Identification of Promoter Motifs Involved in the Network of Phytochrome A-Regulated Gene Expression by Combined Analysis of Genomic Sequence and Microarray Data. Plant Physiology, 133(4), 1605-1616. doi:10.1104/pp.103.030437Jofuku, K. D., den Boer, B. G., Van Montagu, M., & Okamuro, J. K. (1994). Control of Arabidopsis flower and seed development by the homeotic gene APETALA2. The Plant Cell, 6(9), 1211-1225. doi:10.1105/tpc.6.9.1211Kim, Y.-C., Nakajima, M., Nakayama, A., & Yamaguchi, I. (2005). Contribution of Gibberellins to the Formation of Arabidopsis Seed Coat Through Starch Degradation. Plant and Cell Physiology, 46(8), 1317-1325. doi:10.1093/pcp/pci141Kotak, S., Vierling, E., Bäumlein, H., & Koskull-Döring, P. von. (2007). A Novel Transcriptional Cascade Regulating Expression of Heat Stress Proteins during Seed Development of Arabidopsis. The Plant Cell, 19(1), 182-195. doi:10.1105/tpc.106.048165Le, B. H., Cheng, C., Bui, A. Q., Wagmaister, J. A., Henry, K. F., Pelletier, J., … Goldberg, R. B. (2010). Global analysis of gene activity during Arabidopsis seed development and identification of seed-specific transcription factors. Proceedings of the National Academy of Sciences, 107(18), 8063-8070. doi:10.1073/pnas.1003530107Leivar, P., & Quail, P. H. (2011). PIFs: pivotal components in a cellular signaling hub. Trends in Plant Science, 16(1), 19-28. doi:10.1016/j.tplants.2010.08.003Liu, L.-J., Zhang, Y.-C., Li, Q.-H., Sang, Y., Mao, J., Lian, H.-L., … Yang, H.-Q. (2008). COP1-Mediated Ubiquitination of CONSTANS Is Implicated in Cryptochrome Regulation of Flowering in Arabidopsis. The Plant Cell, 20(2), 292-306. doi:10.1105/tpc.107.057281De Lucas, M., & Prat, S. (2014). PIFs get BRright: PHYTOCHROME INTERACTING FACTORs as integrators of light and hormonal signals. New Phytologist, 202(4), 1126-1141. doi:10.1111/nph.12725Molina, I., Ohlrogge, J. B., & Pollard, M. (2007). Deposition and localization of lipid polyester in developing seeds of Brassica napus and Arabidopsis thaliana. The Plant Journal, 53(3), 437-449. doi:10.1111/j.1365-313x.2007.03348.xNesi, N., Debeaujon, I., Jond, C., Stewart, A. J., Jenkins, G. I., Caboche, M., & Lepiniec, L. (2002). The TRANSPARENT TESTA16 Locus Encodes the ARABIDOPSIS BSISTER MADS Domain Protein and Is Required for Proper Development and Pigmentation of the Seed Coat. The Plant Cell, 14(10), 2463-2479. doi:10.1105/tpc.004127Ogé, L., Bourdais, G., Bove, J., Collet, B., Godin, B., Granier, F., … Grappin, P. (2008). Protein Repair l-Isoaspartyl Methyltransferase1 Is Involved in Both Seed Longevity and Germination Vigor in Arabidopsis. The Plant Cell, 20(11), 3022-3037. doi:10.1105/tpc.108.058479Ó’Maoiléidigh, D. S., Graciet, E., & Wellmer, F. (2013). Gene networks controllingArabidopsis thalianaflower development. New Phytologist, 201(1), 16-30. doi:10.1111/nph.12444Parcy, F., Valon, C., Kohara, A., Miséra, S., & Giraudat, J. (1997). The ABSCISIC ACID-INSENSITIVE3, FUSCA3, and LEAFY COTYLEDON1 loci act in concert to control multiple aspects of Arabidopsis seed development. The Plant Cell, 9(8), 1265-1277. doi:10.1105/tpc.9.8.1265Park, D. H., Lim, P. O., Kim, J. S., Cho, D. S., Hong, S. H., & Nam, H. G. (2003). The Arabidopsis COG1 gene encodes a Dof domain transcription factor and negatively regulates phytochrome signaling. The Plant Journal, 34(2), 161-171. doi:10.1046/j.1365-313x.2003.01710.xPi, L., Aichinger, E., van der Graaff, E., Llavata-Peris, C. I., Weijers, D., Hennig, L., … Laux, T. (2015). Organizer-Derived WOX5 Signal Maintains Root Columella Stem Cells through Chromatin-Mediated Repression of CDF4 Expression. Developmental Cell, 33(5), 576-588. doi:10.1016/j.devcel.2015.04.024Pollard, M., Beisson, F., Li, Y., & Ohlrogge, J. B. (2008). Building lipid barriers: biosynthesis of cutin and suberin. Trends in Plant Science, 13(5), 236-246. doi:10.1016/j.tplants.2008.03.003Puig, J., Pauluzzi, G., Guiderdoni, E., & Gantet, P. (2012). Regulation of Shoot and Root Development through Mutual Signaling. Molecular Plant, 5(5), 974-983. doi:10.1093/mp/sss047Rajjou, L., & Debeaujon, I. (2008). Seed longevity: Survival and maintenance of high germination ability of dry seeds. Comptes Rendus Biologies, 331(10), 796-805. doi:10.1016/j.crvi.2008.07.021Riechmann, J. L., Heard, J., Martin, G., Reuber, L., -Z., C., Jiang, … -L. Yu, G. (2000). Arabidopsis Transcription Factors: Genome-Wide Comparative Analysis Among Eukaryotes. Science, 290(5499), 2105-2110. doi:10.1126/science.290.5499.2105Sano, N., Rajjou, L., North, H. M., Debeaujon, I., Marion-Poll, A., & Seo, M. (2015). Staying Alive: Molecular Aspects of Seed Longevity. Plant and Cell Physiology, 57(4), 660-674. doi:10.1093/pcp/pcv186Santos-Mendoza, M., Dubreucq, B., Baud, S., Parcy, F., Caboche, M., & Lepiniec, L. (2008). Deciphering gene regulatory networks that control seed development and maturation in Arabidopsis. The Plant Journal, 54(4), 608-620. doi:10.1111/j.1365-313x.2008.03461.xSattler, S. E., Gilliland, L. U., Magallanes-Lundback, M., Pollard, M., & DellaPenna, D. (2004). Vitamin E Is Essential for Seed Longevity and for Preventing Lipid Peroxidation during Germination. The Plant Cell, 16(6), 1419-1432. doi:10.1105/tpc.021360Schwab, R., Ossowski, S., Riester, M., Warthmann, N., & Weigel, D. (2006). Highly Specific Gene Silencing by Artificial MicroRNAs in Arabidopsis. The Plant Cell, 18(5), 1121-1133. doi:10.1105/tpc.105.039834Seo, M., Jikumaru, Y., & Kamiya, Y. (2011). Profiling of Hormones and Related Metabolites in Seed Dormancy and Germination Studies. Methods in Molecular Biology, 99-111. doi:10.1007/978-1-61779-231-1_7Shigeto, J., Kiyonaga, Y., Fujita, K., Kondo, R., & Tsutsumi, Y. (2013). Putative Cationic Cell-Wall-Bound Peroxidase Homologues in Arabidopsis, AtPrx2, AtPrx25, and AtPrx71, Are Involved in Lignification. Journal of Agricultural and Food Chemistry, 61(16), 3781-3788. doi:10.1021/jf400426gSparks, E., Wachsman, G., & Benfey, P. N. (2013). Spatiotemporal signalling in plant development. Nature Reviews Genetics, 14(9), 631-644. doi:10.1038/nrg3541Suzuki, M., & McCarty, D. R. (2008). Functional symmetry of the B3 network controlling seed development. Current Opinion in Plant Biology, 11(5), 548-553. doi:10.1016/j.pbi.2008.06.015Tan, Q. K.-G., & Irish, V. F. (2006). The Arabidopsis Zinc Finger-Homeodomain Genes Encode Proteins with Unique Biochemical Properties That Are Coordinately Expressed during Floral Development. Plant Physiology, 140(3), 1095-1108. doi:10.1104/pp.105.070565Ülker, B., & Somssich, I. E. (2004). WRKY transcription factors: from DNA binding towards biological function. Current Opinion in Plant Biology, 7(5), 491-498. doi:10.1016/j.pbi.2004.07.012Wachsman, G., Sparks, E. E., & Benfey, P. N. (2015). Genes and networks regulating root anatomy and architecture. New Phytologist, 208(1), 26-38. doi:10.1111/nph.13469Weigel, D., Ahn, J. H., Blázquez, M. A., Borevitz, J. O., Christensen, S. K., Fankhauser, C., … Chory, J. (2000). Activation Tagging in Arabidopsis. Plant Physiology, 122(4), 1003-1014. doi:10.1104/pp.122.4.1003Western, T. L., Young, D. S., Dean, G. H., Tan, W. L., Samuels, A. L., & Haughn, G. W. (2003). MUCILAGE-MODIFIED4 Encodes a Putative Pectin Biosynthetic Enzyme Developmentally Regulated by APETALA2, TRANSPARENT TESTA GLABRA1, and GLABRA2 in the Arabidopsis Seed Coat. Plant Physiology, 134(1), 296-306. doi:10.1104/pp.103.035519Xu, H., Wei, Y., Zhu, Y., Lian, L., Xie, H., Cai, Q., … Zhang, J. (2014). Antisense suppression ofLOX3gene expression in rice endosperm enhances seed longevity. Plant Biotechnology Journal, 13(4), 526-539. doi:10.1111/pbi.12277Yamaguchi-Shinozaki, K., & Shinozaki, K. (2005). Organization of cis-acting regulatory elements in osmotic- and cold-stress-responsive promoters. Trends in Plant Science, 10(2), 88-94. doi:10.1016/j.tplants.2004.12.012Yanagisawa, S. (2002). The Dof family of plant transcription factors. Trends in Plant Science, 7(12), 555-560. doi:10.1016/s1360-1385(02)02362-2Zhang, C., Mallery, E. L., Schlueter, J., Huang, S., Fan, Y., Brankle, S., … Szymanski, D. B. (2008). Arabidopsis SCARs Function Interchangeably to Meet Actin-Related Protein 2/3 Activation Thresholds during Morphogenesis. The Plant Cell, 20(4), 995-1011. doi:10.1105/tpc.107.05535

Search for New Physics in e mu X Data at D0 Using Sleuth: A Quasi-Model-Independent Search Strategy for New Physics

We present a quasi-model-independent search for the physics responsible for electroweak symmetry breaking. We define final states to be studied, and construct a rule that identifies a set of relevant variables for any particular final state. A new algorithm ("Sleuth") searches for regions of excess in those variables and quantifies the significance of any detected excess. After demonstrating the sensitivity of the method, we apply it to the semi-inclusive channel e mu X collected in 108 pb^-1 of ppbar collisions at sqrt(s) = 1.8 TeV at the D0 experiment during 1992-1996 at the Fermilab Tevatron. We find no evidence of new high p_T physics in this sample.Comment: 23 pages, 12 figures. Submitted to Physical Review

Search For Heavy Pointlike Dirac Monopoles

We have searched for central production of a pair of photons with high transverse energies in $p\bar p$ collisions at $\sqrt{s} = 1.8$ TeV using $70 pb^{-1}$ of data collected with the D\O detector at the Fermilab Tevatron in 1994--1996. If they exist, virtual heavy pointlike Dirac monopoles could rescatter pairs of nearly real photons into this final state via a box diagram. We observe no excess of events above background, and set lower 95% C.L. limits of $610, 870, or 1580 GeV/c^2$ on the mass of a spin 0, 1/2, or 1 Dirac monopole.Comment: 12 pages, 4 figure

The Dijet Mass Spectrum and a Search for Quark Compositeness in bar{p}p Collisions at sqrt{s} = 1.8 TeV

Using the DZero detector at the 1.8 TeV pbarp Fermilab Tevatron collider, we have measured the inclusive dijet mass spectrum in the central pseudorapidity region |eta_jet| < 1.0 for dijet masses greater than 200 Gev/c^2. We have also measured the ratio of spectra sigma(|eta_jet| < 0.5)/sigma(0.5 < |eta_jet| < 1.0). The order alpha_s^3 QCD predictions are in good agreement with the data and we rule out models of quark compositeness with a contact interaction scale < 2.4 TeV at the 95% confidence level.Comment: 11 pages, 4 figures, 2 tables, submitted to Phys. Rev. Let

Search for High Mass Photon Pairs in p-pbar --> gamma-gamma-jet-jet Events at sqrt(s)=1.8 TeV

A search has been carried out for events in the channel p-barp --> gamma gamma jet jet. Such a signature can characterize the production of a non-standard Higgs boson together with a W or Z boson. We refer to this non-standard Higgs, having standard model couplings to vector bosons but no coupling to fermions, as a "bosonic Higgs." With the requirement of two high transverse energy photons and two jets, the diphoton mass (m(gamma gamma)) distribution is consistent with expected background. A 90(95)% C.L. upper limit on the cross section as a function of mass is calculated, ranging from 0.60(0.80) pb for m(gamma gamma) = 65 GeV/c^2 to 0.26(0.34) pb for m(gamma gamma) = 150 GeV/c^2, corresponding to a 95% C.L. lower limit on the mass of a bosonic Higgs of 78.5 GeV/c^2.Comment: 9 pages, 3 figures. Replacement has new H->gamma gamma branching ratios and corresponding new mass limit

Ratio of the Isolated Photon Cross Sections at \sqrt{s} = 630 and 1800 GeV

The inclusive cross section for production of isolated photons has been measured in \pbarp collisions at $\sqrt{s} = 630$ GeV with the \D0 detector at the Fermilab Tevatron Collider. The photons span a transverse energy ($E_T$) range from 7-49 GeV and have pseudorapidity $|\eta| < 2.5$. This measurement is combined with to previous \D0 result at $\sqrt{s} = 1800$ GeV to form a ratio of the cross sections. Comparison of next-to-leading order QCD with the measured cross section at 630 GeV and ratio of cross sections show satisfactory agreement in most of the $E_T$ range.Comment: 7 pages. Published in Phys. Rev. Lett. 87, 251805, (2001

Probing Hard Color-Singlet Exchange in ppbar Collisions at root-s=630 GeV and 1800 GeV

We present results on dijet production via hard color-singlet exchange in proton-antiproton collisions at root-s = 630 GeV and 1800 GeV using the DZero detector. The fraction of dijet events produced via color-singlet exchange is measured as a function of jet transverse energy, separation in pseudorapidity between the two highest transverse energy jets, and proton-antiproton center-of-mass energy. The results are consistent with a color-singlet fraction that increases with an increasing fraction of quark-initiated processes and inconsistent with two-gluon models for the hard color-singlet.Comment: 16 pages, 6 figure