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Myotubularin-related proteins regulate KRAS function by controlling plasma membrane levels of polyphosphoinositides and phosphatidylserine. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.22.576612. [PMID: 38328115 PMCID: PMC10849561 DOI: 10.1101/2024.01.22.576612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
KRAS is a small GTPase, ubiquitously expressed in mammalian cells, that functions as a molecular switch to regulate cell proliferation and differentiation. Oncogenic mutations that render KRAS constitutively active occur frequently in human cancers. KRAS must localize to the plasma membrane (PM) for biological activity. KRAS PM binding is mediated by interactions of the KRAS membrane anchor with phosphatidylserine (PtdSer), therefore, depleting PM PtdSer content abrogates KRAS PM binding and oncogenic function. From a genome-wide siRNA screen to search for genes that regulate KRAS PM localization, we identified a set of phosphatidylinositol (PI) 3-phosphatase family members: myotubularin-related (MTMR) proteins 2, 3, 4 and 7. Here we show that knockdown of MTMR 2/3/4/7 expression disrupts KRAS PM interactions. The molecular mechanism involves depletion of PM PI 4-phosphate (PI4P) levels, which in turn disrupts the subcellular localization and operation of oxysterol-binding protein related protein (ORP) 5, a PtdSer lipid transfer protein that maintains PM PtdSer content. Concomitantly, silencing MTMR 2/3/4/7 expression elevates PM levels of PI3P and reduces PM and total cellular levels of PtdSer. In summary we propose that the PI 3-phosphatase activity provided by MTMR proteins is required to generate PM PI for the synthesis of PM PI4P, which in turn, promotes the PM localization of PtdSer and KRAS.
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POCUS for Diastolic Dysfunction: A Review of the Literature. POCUS JOURNAL 2023; 8:88-92. [PMID: 37152335 PMCID: PMC10155731 DOI: 10.24908/pocus.v8i1.15803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Emergency and critical care physicians frequently encounter patients presenting with dyspnea and normal left ventricular systolic function who may benefit from early diastolic evaluation to determine acute patient management. The current American Society of Echocardiography Guidelines approach to diastolic evaluation is often impractical for point of care ultrasound (POCUS) evaluation, and few studies have evaluated the potential use of a simplified approach. This article reviews the literature on the use of a simplified diastolic evaluation to assist in determining acute patient management.
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Depletion of phosphatidylinositol 4-phosphate at the Golgi translocates K-Ras to mitochondria. J Cell Sci 2019; 132:jcs.231886. [PMID: 31331963 DOI: 10.1242/jcs.231886] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 07/12/2019] [Indexed: 01/05/2023] Open
Abstract
Ras proteins are small GTPases localized to the plasma membrane (PM), which regulate cellular proliferation, apoptosis and differentiation. After a series of post-translational modifications, H-Ras and N-Ras traffic to the PM from the Golgi via the classical exocytic pathway, but the exact mechanism of K-Ras trafficking to the PM from the ER is not fully characterized. ATP5G1 (also known as ATP5MC1) is one of the three proteins that comprise subunit c of the F 0 complex of the mitochondrial ATP synthase. In this study, we show that overexpression of the mitochondrial targeting sequence of ATP5G1 perturbs glucose metabolism, inhibits oncogenic K-Ras signaling, and redistributes phosphatidylserine (PtdSer) to mitochondria and other endomembranes, resulting in K-Ras translocation to mitochondria. Also, it depletes phosphatidylinositol 4-phosphate (PI4P) at the Golgi. Glucose supplementation restores PtdSer and K-Ras PM localization and PI4P at the Golgi. We further show that inhibition of the Golgi-localized PI4-kinases (PI4Ks) translocates K-Ras, and PtdSer to mitochondria and endomembranes, respectively. We conclude that PI4P at the Golgi regulates the PM localization of PtdSer and K-Ras.This article has an associated First Person interview with the first author of the paper.
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Beam Energy and Centrality Dependence of Direct-Photon Emission from Ultrarelativistic Heavy-Ion Collisions. PHYSICAL REVIEW LETTERS 2019; 123:022301. [PMID: 31386493 DOI: 10.1103/physrevlett.123.022301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 04/27/2019] [Indexed: 06/10/2023]
Abstract
The PHENIX collaboration presents first measurements of low-momentum (0.4<p_{T}<3 GeV/c) direct-photon yields from Au+Au collisions at sqrt[s_{NN}]=39 and 62.4 GeV. For both beam energies the direct-photon yields are substantially enhanced with respect to expectations from prompt processes, similar to the yields observed in Au+Au collisions at sqrt[s_{NN}]=200. Analyzing the photon yield as a function of the experimental observable dN_{ch}/dη reveals that the low-momentum (>1 GeV/c) direct-photon yield dN_{γ}^{dir}/dη is a smooth function of dN_{ch}/dη and can be well described as proportional to (dN_{ch}/dη)^{α} with α≈1.25. This scaling behavior holds for a wide range of beam energies at the Relativistic Heavy Ion Collider and the Large Hadron Collider, for centrality selected samples, as well as for different A+A collision systems. At a given beam energy, the scaling also holds for high p_{T} (>5 GeV/c), but when results from different collision energies are compared, an additional sqrt[s_{NN}]-dependent multiplicative factor is needed to describe the integrated-direct-photon yield.
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Phospholipase D isoforms differentially regulate leukocyte responses to acute lung injury. J Leukoc Biol 2018; 103:919-932. [PMID: 29437245 DOI: 10.1002/jlb.3a0617-252rr] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 01/03/2018] [Accepted: 01/10/2018] [Indexed: 12/30/2022] Open
Abstract
Phospholipase D (PLD) plays important roles in cellular responses to tissue injury that are critical to acute inflammatory diseases, such as the acute respiratory distress syndrome (ARDS). We investigated the expression of PLD isoforms and related phospholipid phosphatases in patients with ARDS, and their roles in a murine model of self-limited acute lung injury (ALI). Gene expression microarray analysis on whole blood obtained from patients that met clinical criteria for ARDS and clinically matched controls (non-ARDS) demonstrated that PLD1 gene expression was increased in patients with ARDS relative to non-ARDS and correlated with survival. In contrast, PLD2 expression was associated with mortality. In a murine model of self-resolving ALI, lung Pld1 expression increased and Pld2 expression decreased 24 h after intrabronchial acid. Total lung PLD activity was increased 24 h after injury. Pld1-/- mice demonstrated impaired alveolar barrier function and increased tissue injury relative to WT and Pld2-/- , whereas Pld2-/- mice demonstrated increased recruitment of neutrophils and macrophages, and decreased tissue injury. Isoform-specific PLD inhibitors mirrored the results with isoform-specific Pld-KO mice. PLD1 gene expression knockdown in human leukocytes was associated with decreased phagocytosis by neutrophils, whereas reactive oxygen species production and phagocytosis decreased in M2-macrophages. PLD2 gene expression knockdown increased neutrophil and M2-macrophage transmigration, and increased M2-macrophage phagocytosis. These results uncovered selective regulation of PLD isoforms after ALI, and opposing effects of selective isoform knockdown on host responses and tissue injury. These findings support therapeutic strategies targeting specific PLD isoforms for the treatment of ARDS.
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Astronomical time-of-flight photon speedometer. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:094501. [PMID: 28964243 DOI: 10.1063/1.4986226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A dual-band, fiber-optic, photon time-of-flight instrument was developed. Its design was optimized for measuring the velocity of visible photons emanating from relatively dim astronomical sources (apparent magnitude m>12), such as distant galaxies and quasars. We report the first direct photon group velocity measurements for extragalactic objects. The photon group velocity is found to be 3.00±0.03×108 ms-1 and is invariant, within experimental error, over the range of redshifts measured (0≤z≤1.33). This measurement provides additional validation of general relativity and is consistent with the Friedmann-Lemaître-Robertson-Walker and hyperbolic anti-de Sitter metrics but not with the elliptical de Sitter metric.
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How miRs and mRNA deadenylases could post-transcriptionally regulate expression of tumor-promoting protein PLD. Adv Biol Regul 2017; 68:107-119. [PMID: 28964725 DOI: 10.1016/j.jbior.2017.08.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 08/19/2017] [Accepted: 08/21/2017] [Indexed: 12/11/2022]
Abstract
Phospholipase D (PLD) plays a key role in both cell membrane lipid reorganization and architecture, as well as a cell signaling protein via the product of its enzymatic reaction, phosphatidic acid (PA). PLD is involved in promoting breast cancer cell growth, proliferation, and metastasis and both gene and protein expression are upregulated in breast carcinoma human samples. In spite of all this, the ultimate reason as to why PLD expression is high in cancer cells vs. their normal counterparts remains largely unknown. Until we understand this and the associated signaling pathways, it will be difficult to establish PLD as a bona fide target to explore new potential cancer therapeutic approaches. Recently, our lab has identified several molecular mechanisms by which PLD expression is high in breast cancer cells and they all involve post-transcriptional control of its mRNA. First, PA, a mitogen, functions as a protein and mRNA stabilizer that counteracts natural decay and degradation. Second, there is a repertoire of microRNAs (miRs) that keep PLD mRNA translation at low levels in normal cells, but their effects change with starvation and during endothelial-to-mesenchymal transition (EMT) in cancer cells. Third, there is a novel way of post-transcriptional regulation of PLD involving 3'-exonucleases, specifically the deadenylase, Poly(A)-specific Ribonuclease (PARN), which tags mRNA for mRNA for degradation. This would enable PLD accumulation and ultimately breast cancer cell growth. We review in depth the emerging field of post-transcriptional regulation of PLD, which is only recently beginning to be understood. Since, surprisingly, so little is known about post-transcriptional regulation of PLD and related phospholipases (PLC or PLA), this new knowledge could help our understanding of how post-transcriptional deregulation of a lipid enzyme expression impacts tumor growth.
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A feedback mechanism between PLD and deadenylase PARN for the shortening of eukaryotic poly(A) mRNA tails that is deregulated in cancer cells. Biol Open 2017; 6:176-186. [PMID: 28011629 PMCID: PMC5312095 DOI: 10.1242/bio.021261] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The removal of mRNA transcript poly(A) tails by 3′→5′ exonucleases is the rate-limiting step in mRNA decay in eukaryotes. Known cellular deadenylases are the CCR4-NOT and PAN complexes, and poly(A)-specific ribonuclease (PARN). The physiological roles and regulation for PARN is beginning to be elucidated. Since phospholipase D (PLD2 isoform) gene expression is upregulated in breast cancer cells and PARN is downregulated, we examined whether a signaling connection existed between these two enzymes. Silencing PARN with siRNA led to an increase in PLD2 protein, whereas overexpression of PARN had the opposite effect. Overexpression of PLD2, however, led to an increase in PARN expression. Thus, PARN downregulates PLD2 whereas PLD2 upregulates PARN. Co-expression of both PARN and PLD2 mimicked this pattern in non-cancerous cells (COS-7 fibroblasts) but, surprisingly, not in breast cancer MCF-7 cells, where PARN switches from inhibition to activation of PLD2 gene and protein expression. Between 30 and 300 nM phosphatidic acid (PA), the product of PLD enzymatic reaction, added exogenously to culture cells had a stabilizing role of both PARN and PLD2 mRNA decay. Lastly, by immunofluorescence microscopy, we observed an intracellular co-localization of PA-loaded vesicles (0.1-1 nm) and PARN. In summary, we report for the first time the involvement of a phospholipase (PLD2) and PA in mediating PARN-induced eukaryotic mRNA decay and the crosstalk between the two enzymes that is deregulated in breast cancer cells. Summary: Cell signaling enzyme phospholipase D2 (PLD2) and its reaction product, phospholipid phosphatidic acid (PA), are involved in mediating PARN-induced eukaryotic mRNA decay.
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Measurements of Elliptic and Triangular Flow in High-Multiplicity 3He+Au Collisions at √(s(NN))=200 GeV. PHYSICAL REVIEW LETTERS 2015; 115:142301. [PMID: 26551807 DOI: 10.1103/physrevlett.115.142301] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Indexed: 06/05/2023]
Abstract
We present the first measurement of elliptic (v(2)) and triangular (v(3)) flow in high-multiplicity (3)He+Au collisions at √(s(NN))=200 GeV. Two-particle correlations, where the particles have a large separation in pseudorapidity, are compared in (3)He+Au and in p+p collisions and indicate that collective effects dominate the second and third Fourier components for the correlations observed in the (3)He+Au system. The collective behavior is quantified in terms of elliptic v(2) and triangular v(3) anisotropy coefficients measured with respect to their corresponding event planes. The v(2) values are comparable to those previously measured in d+Au collisions at the same nucleon-nucleon center-of-mass energy. Comparisons with various theoretical predictions are made, including to models where the hot spots created by the impact of the three (3)He nucleons on the Au nucleus expand hydrodynamically to generate the triangular flow. The agreement of these models with data may indicate the formation of low-viscosity quark-gluon plasma even in these small collision systems.
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Gastrointestinal morbidity as primary outcome measure in studies comparing crystalloid and colloid within a goal-directed therapy. Br J Anaesth 2015; 115:128-9. [PMID: 26089448 DOI: 10.1093/bja/aev181] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
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Medium modification of jet fragmentation in Au+Au collisions at √[s(NN)]=200 GeV measured in direct photon-hadron correlations. PHYSICAL REVIEW LETTERS 2013; 111:032301. [PMID: 23909311 DOI: 10.1103/physrevlett.111.032301] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Indexed: 06/02/2023]
Abstract
The jet fragmentation function is measured with direct photon-hadron correlations in p+p and Au+Au collisions at √[s(NN)]=200 GeV. The p(T) of the photon is an excellent approximation to the initial p(T) of the jet and the ratio z(T)=p(T)(h)/p(T)(γ) is used as a proxy for the jet fragmentation function. A statistical subtraction is used to extract the direct photon-hadron yields in Au+Au collisions while a photon isolation cut is applied in p+p. I(AA), the ratio of hadron yield opposite the photon in Au+Au to that in p+p, indicates modification of the jet fragmentation function. Suppression, most likely due to energy loss in the medium, is seen at high z(T). The associated hadron yield at low z(T) is enhanced at large angles. Such a trend is expected from redistribution of the lost energy into increased production of low-momentum particles.
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Measurement of direct photons in Au+Au collisions at √(s(NN))=200 GeV. PHYSICAL REVIEW LETTERS 2012; 109:152302. [PMID: 23102300 DOI: 10.1103/physrevlett.109.152302] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2012] [Indexed: 06/01/2023]
Abstract
We report the measurement of direct photons at midrapidity in Au+Au collisions at √(s(NN))=200 GeV. The direct photon signal was extracted for the transverse momentum range of 4 GeV/c<p(T)<22 GeV/c, using a statistical method to subtract decay photons from the inclusive photon sample. The direct photon nuclear modification factor R(AA) was calculated as a function of p(T) for different Au+Au collision centralities using the measured p+p direct photon spectrum and compared to theoretical predictions. R(AA) was found to be consistent with unity for all centralities over the entire measured p(T) range. Theoretical models that account for modifications of initial direct photon production due to modified parton distribution functions in Au and the different isospin composition of the nuclei predict a modest change of R(AA) from unity. They are consistent with the data. Models with compensating effects of the quark-gluon plasma on high-energy photons, such as suppression of jet-fragmentation photons and induced-photon bremsstrahlung from partons traversing the medium, are also consistent with this measurement.
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Abstract
Primer-induced in situ hybridization of high copy sequences was used successfully on rye mitotic chromosome spreads. Nucleolus organizer sequences were detected in rye, and the pattern obtained was in full agreement with previously reported results by conventional in situ hybridization. The future potential of the primer-induced in situ hybridization technique is briefly discussed.
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Detection of ribosomal DNA sites in lentil and chickpea by fluorescent in situ hybridization. Genome 2012; 37:713-6. [PMID: 18470114 DOI: 10.1139/g94-101] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hybridization sites of an rDNA probe coding for the 18S, 5.8S, and 26S genes were detected on lentil and chickpea somatic chromosomes using fluorescent in situ hybridization. One pair of hybridization sites was detected in cultivated lentil Lens culinaris L. and wild lentil L. orientalis (Boiss.) Hand.-Mazz., and in both the hybridization sites of the ribosomal probe correspond to the secondary constriction. In cultivated chickpea Cicer arietinum three pairs of rDNA sites were detected and in the wild C. reticulatum two pairs were detected. The karyotypic relationship between the cultivated C. arietinum and its wild progenitor C. reticulatum is discussed.
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Abstract
Twenty-three wheat/alien addition or substitution lines were screened using restriction fragment length polymorphisms for the presence or absence of 4/5 and 4/7 reciprocal translocations in the alien chromosomes. Such translocations have previously been identified in wheat and rye. Group 4 and group 5 Aegilops umbellulata, Triticum urartu, and Thinopyrum bessarabicum chromosomes were found to carry 4/5 translocations. Evidence for a 4/7 translocation was also found in Secale montanum. The presence of the 4/5 translocations in T. urartu indicates that the translocation predates the polyploidization of wheat. The implications of these results are discussed.
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Abstract
The predatory sun star, Heliaster kubiniji, once the commonest rocky intertidal asteroid of the Gulf of California, has been rare throughout this region since summer 1978 when a devastating disease outbreak occurred. This unprecedented phenomenon and several other exceptional ecological events in marine communities of the northeastern Pacific appear to be linked to large-scale climatic changes that occurred during 1977 and 1978. Implications of the decline in Heliaster kubiniji are discussed.
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Metabolic event involved in the bactericidal activity of normal mouse macrophages. Infect Immun 2010; 3:390-7. [PMID: 16557985 PMCID: PMC416163 DOI: 10.1128/iai.3.3.390-397.1971] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The intracellular bactericidal activity of normal mouse peritoneal macrophages requires a viable, actively metabolizing cell. The killing mechanism is apparently dependent upon an intact respiratory electron chain since inhibition of activity is achieved by anaerobiosis, cyanide, antimycin A, or amytal. By way of contrast, inhibitors of oxidative phosphorylation, glycolysis, the Krebs citric acid cycle, and the phosphogluconate oxidative pathway are without influence on this antibacterial activity. Various dyes and electron acceptors with selected reduction-oxidation values also inhibit killing. Although the bactericidal substance was not identified, the data are consistent with the hypothesis that the primary agent is hydrogen peroxide.
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Enhanced production of direct photons in Au + Au collisions at square root(S(NN)) = 200 GeV and implications for the initial temperature. PHYSICAL REVIEW LETTERS 2010; 104:132301. [PMID: 20481877 DOI: 10.1103/physrevlett.104.132301] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2008] [Revised: 12/02/2009] [Indexed: 05/29/2023]
Abstract
The production of e+ e- pairs for m(e+ e-)<0.3 GeV/c2 and 1<p(T)<5 GeV/c is measured in p+p and Au+Au collisions at square root(S(NN))=200 GeV. An enhanced yield above hadronic sources is observed. Treating the excess as photon internal conversions, the invariant yield of direct photons is deduced. In central Au+Au collisions, the excess of the direct photon yield over p+p is exponential in transverse momentum, with an inverse slope T=221+/-19(stat)+/-19(syst) MeV. Hydrodynamical models with initial temperatures ranging from T(init) approximately 300-600 MeV at times of approximately 0.6-0.15 fm/c after the collision are in qualitative agreement with the data. Lattice QCD predicts a phase transition to quark gluon plasma at approximately 170 MeV.
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Charged Kaon interferometric probes of space-time evolution in Au+Au collisions at sqrt[S(NN)]=200 GeV. PHYSICAL REVIEW LETTERS 2009; 103:142301. [PMID: 19905563 DOI: 10.1103/physrevlett.103.142301] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2009] [Indexed: 05/28/2023]
Abstract
Bose-Einstein correlations of charged kaons are used to probe Au+Au collisions at sqrt[S(NN)]=200 GeV and are compared to charged pion probes, which have a larger hadronic scattering cross section. Three-dimensional Gaussian source radii are extracted, along with a one-dimensional kaon emission source function. The centrality dependences of the three Gaussian radii are well described by a single linear function of N(part)1/3 with a zero intercept. Imaging analysis shows a deviation from a Gaussian tail at r greater than or approximately equal to 10 fm, although the bulk emission at lower radius is well described by a Gaussian. The presence of a non-Gaussian tail in the kaon source reaffirms that the particle emission region in a heavy-ion collision is extended, and that similar measurements with pions are not solely due to the decay of long-lived resonances.
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Measurement of bottom versus charm as a function of transverse momentum with electron-hadron correlations in p + p collisions at square root of s = 200 GeV. PHYSICAL REVIEW LETTERS 2009; 103:082002. [PMID: 19792719 DOI: 10.1103/physrevlett.103.082002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2009] [Indexed: 05/28/2023]
Abstract
The momentum distribution of electrons from semileptonic decays of charm and bottom quarks for midrapidity |y|<0.35 in p+p collisions at square root of s=200 GeV is measured by the PHENIX experiment at the Relativistic Heavy Ion Collider over the transverse momentum range 2<pT<7 GeV/c. The ratio of the yield of electrons from bottom to that from charm is presented. The ratio is determined using partial D/D-->e(+/-)K(-/+)X (K unidentified) reconstruction. It is found that the yield of electrons from bottom becomes significant above 4 GeV/c in pT. A fixed-order-plus-next-to-leading-log perturbative quantum chromodynamics calculation agrees with the data within the theoretical and experimental uncertainties. The extracted total bottom production cross section at this energy is sigma(bb)=3.2(-1.1)(+1.2)(stat)(-1.3)(+1.4)(syst)mub.
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MicroRNA-221/222 confers tamoxifen resistance in breast cancer by targeting p27(kip1). Cancer Res 2009. [DOI: 10.1158/0008-5472.sabcs-3023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Abstract #3023
Background: Breast cancer is the most common malignancy in women, accounting for 31% of all female cancers. Over two-thirds of breast cancers exhibit high concentrations of estrogen receptor, which contribute to tumor growth and progression. Blocking the steroid hormone pathway with tamoxifen and/or oophorectomy has been shown to be effective in this patient population. However, approximately 30% of the breast cancer is resistant to tamoxifen. Recent studies have highlighted the key regulatory roles of microRNAs (miR) in all fundamental cellular processes in animals and plants including primary human cancers. We hypothesized that alteration in the expression of specific miRs in breast cancer could contribute to tamoxifen resistance.
 Methods: To test this hypothesis, we performed microRNA microarray analysis using MCF-7 cell lines that are either sensitive (parental) or resistant to tamoxifen (4-hydroxy tamoxifen resistant-OHTR). Using Real-time RT-PCR we validated altered expression of the miRs in both the cell culture model and the primary human breast cancer tissues. Cells overexpressing miR-221/222 or p27(kip1) were created by transfection of mammalian expression vectors using Lipofectamine2000 followed by G418 selection. Cell viability upon tamoxifen treatment was measured by MTT assay, extent of apoptosis was monitored by Western blot analysis of PAPR and Caspase cleavage and cell cycle profile was studied using Flow cytometry.
 Results: Eight miRs were found to be significantly upregulated while seven miRs were significantly down-regulated in the OHTR cells compared to parental MCF-7 cells. The increased expression of three upregulated (miR-221, miR-222 and miR-181) and three downregulated (miR-21, miR-342 and miR-489) miRs was later validated in the cell lines by real-time RT-PCR. In addition, the level of miR-221 and miR-222 was significantly elevated in Her2/neu(+) primary human breast cancer tissues, compared to Her2/neu(-) tissue samples. The Her2/neu expressing tumors are known to be relatively resistant to endocrine therapy. Ectopic expression of miR-221/miR-222 in parental MCF-7 cells rendered the cells more tolerant to tamoxifen than the control cells. The cell cycle inhibitor p27/Kip1, a known target of miR-221/miR-222 was significantly reduced in both OHTR cells and miR-221/222 overexpressing MCF-7 cells, which was consistent with the upregulation of the miRs. Ectopic expression of p27/Kip1 in the resistant OHTR cells enhanced cell death when exposed to tamoxifen.
 Conclusion: This study has revealed a specific miR signature for the tamoxifen-resistant breast cancer and an important cell cycle inhibitor target of the altered miR, which could be used as a prognostic marker for the drug-resistant breast cancer. Further studies of other miRs differentially expressed in tamoxifen resistant cell lines, will help us not only in identifying such patients but also may serve as a therapeutic target in the future.
Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3023.
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Suppression pattern of neutral pions at high transverse momentum in Au + Au collisions at sqrt[sNN]=200 GeV and constraints on medium transport coefficients. PHYSICAL REVIEW LETTERS 2008; 101:232301. [PMID: 19113542 DOI: 10.1103/physrevlett.101.232301] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2008] [Indexed: 05/27/2023]
Abstract
For Au + Au collisions at 200 GeV, we measure neutral pion production with good statistics for transverse momentum, pT, up to 20 GeV/c. A fivefold suppression is found, which is essentially constant for 5 < pT < 20 GeV/c. Experimental uncertainties are small enough to constrain any model-dependent parametrization for the transport coefficient of the medium, e.g., q in the parton quenching model. The spectral shape is similar for all collision classes, and the suppression does not saturate in Au + Au collisions.
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Onset of pi(0) suppression studied in Cu+Cu collisions at sqrt S NN=22.4, 62.4, and 200 GeV. PHYSICAL REVIEW LETTERS 2008; 101:162301. [PMID: 18999660 DOI: 10.1103/physrevlett.101.162301] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2008] [Indexed: 05/27/2023]
Abstract
Neutral pion transverse momentum (p(T)) spectra at midrapidity (|y| less than or approximately 0.35) were measured in Cu+Cu collisions at sqrt[s(NN)]=22.4, 62.4, and 200 GeV. Relative to pi_(0) yields in p+p collisions scaled by the number of inelastic nucleon-nucleon collisions (N(coll) the pi_(0) yields for p(T) more than or approximately 2 GeV/c in central Cu+Cu collisions are suppressed at 62.4 and 200 GeV whereas an enhancement is observed at 22.4 GeV. A comparison with a jet-quenching model suggests that final state parton energy loss dominates in central Cu+Cu collisions at 62.4 and 200 GeV, while the enhancement at 22.4 GeV is consistent with nuclear modifications in the initial state alone.
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J/psi production in sqrt s_NN=200 GeV Cu+Cu collisions. PHYSICAL REVIEW LETTERS 2008; 101:122301. [PMID: 18851363 DOI: 10.1103/physrevlett.101.122301] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2007] [Indexed: 05/26/2023]
Abstract
Yields for J/psi production in Cu+Cu collisions at sqrt s_NN=200 GeV have been measured over the rapidity range |y|<2.2 and compared with results in p+p and Au+Au collisions at the same energy. The Cu+Cu data offer greatly improved precision over existing Au+Au data for J/psi production in collisions with small to intermediate numbers of participants, in the range where the quark-gluon plasma transition threshold is predicted to lie. Cold nuclear matter estimates based on ad hoc fits to d+Au data describe the Cu+Cu data up to N_part approximately 50, corresponding to a Bjorken energy density of at least 1.5 GeV/fm(3).
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25
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Particle-species dependent modification of jet-induced correlations in Au+Au collisions at sqrt[s_{NN}]=200 GeV. PHYSICAL REVIEW LETTERS 2008; 101:082301. [PMID: 18764605 DOI: 10.1103/physrevlett.101.082301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2007] [Indexed: 05/26/2023]
Abstract
Measurements in Au+Au collisions at sqrt[s_{NN}]=200 GeV of jet correlations for a trigger hadron at intermediate transverse momentum (p_{T,trig}) with associated mesons or baryons at lower p_{T,assoc} indicate strong modification of the away-side jet. The ratio of jet-associated baryons to mesons increases with centrality and p_{T,assoc}. For the most central collisions, the ratio is similar to that for inclusive measurements. This trend is incompatible with in-vacuum fragmentation but could be due to jetlike contributions from correlated soft partons, which recombine upon hadronization.
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26
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Source breakup dynamics in Au + Au collisions at sqrt[s(NN)]=200 GeV via three-dimensional two-pion source imaging. PHYSICAL REVIEW LETTERS 2008; 100:232301. [PMID: 18643489 DOI: 10.1103/physrevlett.100.232301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2007] [Indexed: 05/26/2023]
Abstract
A three-dimensional correlation function obtained from midrapidity, low p(T), pion pairs in central Au+Au collisions at sqrt[s(NN)]=200 GeV is studied. The extracted model-independent source function indicates a long range tail in the directions of the pion pair transverse momentum (out) and the beam (long). A proper breakup time tau(0) ~ 9 fm/c and a mean proper emission duration Delta tau ~ 2 fm/c, leading to sizable emission time differences ({|Delta t(LCM)|} approximately 12 fm/c), are required to allow models to be successfully matched to these tails. The model comparisons also suggest an outside-in "burning" of the emission source reminiscent of many hydrodynamical models.
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27
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Elliptic flow for phi mesons and (anti)deuterons in Au+Au collisions at square root of sNN=200 GeV. PHYSICAL REVIEW LETTERS 2007; 99:052301. [PMID: 17930746 DOI: 10.1103/physrevlett.99.052301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2007] [Indexed: 05/25/2023]
Abstract
Differential elliptic flow (v(2)) for phi mesons and (anti)deuterons (d)d is measured for Au+Au collisions at square root of sNN=200 GeV. The v(2) for phi mesons follows the trend of lighter pi+/- and K+/- mesons, suggesting that ordinary hadrons interacting with standard hadronic cross sections are not the primary driver for elliptic flow development. The v(2) values for (d)d suggest that elliptic flow is additive for composite particles. This further validation of the universal scaling of v(2) per constituent quark for baryons and mesons suggests that partonic collectivity dominates the transverse expansion dynamics.
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28
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System size and energy dependence of jet-induced hadron pair correlation shapes in Cu+Cu and Au+Au collisions at square root sNN=200 and 62.4 GeV. PHYSICAL REVIEW LETTERS 2007; 98:232302. [PMID: 17677902 DOI: 10.1103/physrevlett.98.232302] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2006] [Indexed: 05/16/2023]
Abstract
We present azimuthal angle correlations of intermediate transverse momentum (1-4 GeV/c) hadrons from dijets in Cu+Cu and Au+Au collisions at square root sNN=62.4 and 200 GeV. The away-side dijet induced azimuthal correlation is broadened, non-Gaussian, and peaked away from Delta phi=pi in central and semicentral collisions in all the systems. The broadening and peak location are found to depend upon the number of participants in the collision, but not on the collision energy or beam nuclei. These results are consistent with sound or shock wave models, but pose challenges to Cherenkov gluon radiation models.
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29
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J/psi production versus transverse momentum and rapidity in p+p collisions at square root s=200 GeV. PHYSICAL REVIEW LETTERS 2007; 98:232002. [PMID: 17677900 DOI: 10.1103/physrevlett.98.232002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2006] [Indexed: 05/16/2023]
Abstract
J/psi production in p+p collisions at square root s=200 GeV has been measured by the PHENIX experiment at the BNL Relativistic Heavy Ion Collider over a rapidity range of -2.2<y<2.2 and a transverse momentum range of 0<pT<9 GeV/c. The size of the present data set allows a detailed measurement of both the pT and the rapidity distributions and is sufficient to constrain production models. The total cross section times the branching ratio is Bll sigma pp J/psi=178+/-3stat+/-53sys+/-18norm nb.
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30
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J/psi production versus centrality, transverse momentum, and rapidity in Au+Au collisions at square root sNN=200 GeV. PHYSICAL REVIEW LETTERS 2007; 98:232301. [PMID: 17677901 DOI: 10.1103/physrevlett.98.232301] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2006] [Indexed: 05/16/2023]
Abstract
The PHENIX experiment at the BNL Relativistic Heavy Ion Collider (RHIC) has measured J/psi production for rapidities -2.2<y<2.2 in Au+Au collisions at square root sNN=200 GeV. The J/psi invariant yield and nuclear modification factor RAA as a function of centrality, transverse momentum, and rapidity are reported. A suppression of J/psi relative to binary collision scaling of proton-proton reaction yields is observed. Models which describe the lower energy J/psi data at the CERN Super Proton Synchrotron invoking only J/psi destruction based on the local medium density predict a significantly larger suppression at RHIC and more suppression at midrapidity than at forward rapidity. Both trends are contradicted by our data.
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31
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Evaluating Support for the Resource‐Ratio Hypothesis: A Reply to Wilson et al. Am Nat 2007; 169:707-8. [PMID: 17427141 DOI: 10.1086/513110] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2006] [Accepted: 09/22/2006] [Indexed: 11/03/2022]
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32
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Scaling properties of azimuthal anisotropy in Au+Au and Cu+Cu Collisions at sqrt[s NN]=200 GeV. PHYSICAL REVIEW LETTERS 2007; 98:162301. [PMID: 17501413 DOI: 10.1103/physrevlett.98.162301] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2006] [Indexed: 05/15/2023]
Abstract
Differential measurements of elliptic flow (v2) for Au+Au and Cu+Cu collisions at sqrt[sNN]=200 GeV are used to test and validate predictions from perfect fluid hydrodynamics for scaling of v2 with eccentricity, system size, and transverse kinetic energy (KE T). For KE T identical with mT-m up to approximately 1 GeV the scaling is compatible with hydrodynamic expansion of a thermalized fluid. For large values of KE T mesons and baryons scale separately. Quark number scaling reveals a universal scaling of v2 for both mesons and baryons over the full KE T range for Au+Au. For Au+Au and Cu+Cu the scaling is more pronounced in terms of KE T, rather than transverse momentum.
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33
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Evidence for a long-range component in the pion emission source in Au+Au collisions at sqrt sNN=200 GeV. PHYSICAL REVIEW LETTERS 2007; 98:132301. [PMID: 17501193 DOI: 10.1103/physrevlett.98.132301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2006] [Indexed: 05/15/2023]
Abstract
Emission source functions are extracted from correlation functions constructed from charged pions produced at midrapidity in Au+Au collisions at sqrt[s(NN)]=200 GeV. The source parameters extracted from these functions at low k(T) give first indications of a long tail for the pion emission source. The source extension cannot be explained solely by simple kinematic considerations. The possible role of a halo of secondary pions from resonance emissions is explored.
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34
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Measurement of direct photon production in p+p collisions at sqrt[s] = 200 GeV. PHYSICAL REVIEW LETTERS 2007; 98:012002. [PMID: 17358469 DOI: 10.1103/physrevlett.98.012002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2006] [Indexed: 05/14/2023]
Abstract
Cross sections for midrapidity production of direct photons in p+p collisions at the Relativistic Heavy Ion Collider (RHIC) are reported for transverse momenta of 3 < pT < 16 GeV/c. Next-to-leading order perturbative QCD (pQCD) describes the data well for pT >5 GeV/c, where the uncertainties of the measurement and theory are comparable. We also report on the effect of requiring the photons to be isolated from parton jet energy. The observed fraction of isolated photons is well described by pQCD for pT >7 GeV/c.
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35
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Measurement of high-pT single electrons from heavy-flavor decays in p + p collisions at square root of s = 200 GeV. PHYSICAL REVIEW LETTERS 2006; 97:252002. [PMID: 17280343 DOI: 10.1103/physrevlett.97.252002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2006] [Indexed: 05/13/2023]
Abstract
The momentum distribution of electrons from decays of heavy flavor (charm and bottom) for midrapidity absolute value of y < 0.35 in p + p collisions at square root of s = 200 GeV has been measured by the PHENIX experiment at the BNL Relativistic Heavy Ion Collider over the transverse momentum range 0.3 < pT < 9 GeV/c. Two independent methods have been used to determine the heavy-flavor yields, and the results are in good agreement with each other. A fixed-order-plus-next-to-leading-log perturbative QCD calculation agrees with the data within the theoretical and experimental uncertainties, with the data/theory ratio of 1.71+/-0.02stat+/-0.18sys for 0.3 < pT < 9 GeV/c. The total charm production cross section at this energy has also been deduced to be sigma cc = 567+/-57stat+/-193sys microb.
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36
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Dense-medium modifications to jet-induced hadron pair distributions in Au+Au collisions at sqrt s NN=200 GeV. PHYSICAL REVIEW LETTERS 2006; 97:052301. [PMID: 17026095 DOI: 10.1103/physrevlett.97.052301] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2005] [Indexed: 05/12/2023]
Abstract
Azimuthal correlations of jet-induced high-p(T) charged hadron pairs are studied at midrapidity in Au+Au collisions at sqrt[s(NN)]=200 GeV. The distribution of jet-associated partner hadrons (1.0<p(T)<2.5 GeV/c) per trigger hadron (2.5<p(T)<4.0 GeV/c) is found to vary with collision centrality, in both shape and yield, indicating a significant effect of the nuclear collision medium on the jet fragmentation process.
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37
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Azimuthal angle correlations for rapidity separated Hadron pairs in d+Au collisions at square root of sNN=200 GeV. PHYSICAL REVIEW LETTERS 2006; 96:222301. [PMID: 16803304 DOI: 10.1103/physrevlett.96.222301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2006] [Indexed: 05/10/2023]
Abstract
Deuteron-gold (d+Au) collisions at the Relativistic Heavy Ion Collider provide ideal platforms for testing QCD theories in dense nuclear matter at high energy. In particular, models suggesting strong saturation effects for partons carrying small nucleon momentum fraction (x) predict modifications to jet production at forward rapidity (deuteron-going direction) in d+Au collisions. We report on two-particle azimuthal angle correlations between charged hadrons at forward/backward (deuteron/gold going direction) rapidity and charged hadrons at midrapidity in d+Au and p+p collisions at square root of sNN=200 GeV. Jet structures observed in the correlations are quantified in terms of the conditional yield and angular width of away-side partners. The kinematic region studied here samples partons in the gold nucleus with x~0.1 to ~0.01. Within this range, we find no x dependence of the jet structure in d+Au collisions.
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38
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Common suppression pattern of eta and pi0 mesons at high transverse momentum in Au + Au collisions at square root S(NN) = 200 GeV. PHYSICAL REVIEW LETTERS 2006; 96:202301. [PMID: 16803168 DOI: 10.1103/physrevlett.96.202301] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2006] [Indexed: 05/10/2023]
Abstract
Inclusive transverse momentum spectra of eta mesons have been measured within p(T) = 2-10 GeV/c at midrapidity by the PHENIX experiment in Au + Au collisions at square root S(NN) = 200 GeV. In central Au+Au the eta yields are significantly suppressed compared to peripheral Au + Au, d + Au, and p + p yields scaled by the corresponding number of nucleon-nucleon collisions. The magnitude, centrality, and p(T) dependence of the suppression is common, within errors, for eta and pi0. The ratio of eta to pi0 spectra at high p(T) amounts to 0.40 < R(eta/pi)0 < 0.48 for the three systems, in agreement with the world average measured in hadronic and nuclear reactions and, at large scaled momentum, in e+e- collisions.
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39
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Single electrons from heavy-flavor decays in collisions at. PHYSICAL REVIEW LETTERS 2006; 96:032001. [PMID: 16486684 DOI: 10.1103/physrevlett.96.032001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2005] [Indexed: 05/06/2023]
Abstract
The invariant differential cross section for inclusive electron production in p+p collisions at [FORMULA: SEE TEXT] has been measured by the PHENIX experiment at the BNL Relativistic Heavy Ion Collider over the transverse momentum range 0.4<or=pT<OR=5.0 GeV/c in the central rapidity region ([FORMULA: SEE TEXT]). The contribution to the inclusive electron spectrum from semileptonic decays of hadrons carrying heavy flavor, i.e., charm quarks or, at high , bottom quarks, is determined via three independent methods. The resulting electron spectrum from heavy-flavor decays is compared to recent leading and next-to-leading order perturbative QCD calculations. The total cross section of charm quark-antiquark pair production is determined to be [FORMULA: SEE TEXT].
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40
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Measurement of identified and inclusive photon second-harmonic parameter and implications for direct photon production in [FORMULA: SEE TEXT] Au+Au. PHYSICAL REVIEW LETTERS 2006; 96:032302. [PMID: 16486688 DOI: 10.1103/physrevlett.96.032302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2005] [Indexed: 05/06/2023]
Abstract
The azimuthal distribution of identified pi0 and inclusive photons has been measured in [FORMULA: SEE TEXT] Au+Au collisions with the PHENIX experiment at the Relativistic Heavy-Ion Collider (RHIC). The second-harmonic parameter (nu2) was measured to describe the observed anisotropy of the azimuthal distribution. The measured inclusive photon is consistent with the value expected for the photons from hadron decay and is also consistent with the lack of direct photon signal over the measured pT range 1-6 GeV/c. An attempt is made to extract nu2 of direct photons.
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41
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Nuclear modification of electron spectra and implications for heavy quark energy loss in Au+Au collisions at [FORMULA: SEE TEXT]. PHYSICAL REVIEW LETTERS 2006; 96:032301. [PMID: 16486687 DOI: 10.1103/physrevlett.96.032301] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2005] [Indexed: 05/06/2023]
Abstract
The PHENIX experiment has measured midrapidity ([FORMULA: SEE TEXT]) transverse momentum spectra ([FORMULA: SEE TEXT]) of electrons as a function of centrality in Au+Au collisions at [FORMULA: SEE TEXT]. Contributions from photon conversions and from light hadron decays, mainly Dalitz decays of pi0 and eta mesons, were removed. The resulting nonphotonic electron spectra are primarily due to the semileptonic decays of hadrons carrying heavy quarks. Nuclear modification factors were determined by comparison to nonphotonic electrons in p+p collisions. A significant suppression of electrons at high pT is observed in central Au+Au collisions, indicating substantial energy loss of heavy quarks.
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42
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J/psi production and nuclear effects for d + Au and p + p collisions at square root of S(NN) = 200 GeV. PHYSICAL REVIEW LETTERS 2006; 96:012304. [PMID: 16486446 DOI: 10.1103/physrevlett.96.012304] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2005] [Indexed: 05/06/2023]
Abstract
J/psi production in d + Au and p + p collisions at square root of S(NN) = 200 GeV has been measured by the PHENIX experiment at rapidities -2.2 < y < +2.4. The cross sections and nuclear dependence of J/psi production versus rapidity, transverse momentum, and centrality are obtained and compared to lower energy p + A results and to theoretical models. The observed nuclear dependence in d + Au collisions is found to be modest, suggesting that the absorption in the final state is weak and the shadowing of the gluon distributions is small and consistent with Dokshitzer-Gribov-Lipatov-Altarelli-Parisi-based parametrizations that fit deep-inelastic scattering and Drell-Yan data at lower energies.
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43
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Measurement of transverse single-spin asymmetries for midrapidity production of neutral pions and charged hadrons in polarized p + p collisions at square root(s) = 200 GeV. PHYSICAL REVIEW LETTERS 2005; 95:202001. [PMID: 16384048 DOI: 10.1103/physrevlett.95.202001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2005] [Indexed: 05/05/2023]
Abstract
Transverse single-spin asymmetries to probe the transverse-spin structure of the proton have been measured for neutral pions and nonidentified charged hadrons from polarized proton-proton collisions at midrapidity and square root(s) = 200 GeV. The data cover a transverse momentum (pT) range 1.0-5.0 GeV/c for neutral pions and 0.5-5.0 GeV/c for charged hadrons, at a Feynman-x value of approximately zero. The asymmetries seen in this previously unexplored kinematic region are consistent with zero within errors of a few percent. In addition, the inclusive charged hadron cross section at midrapidity from 0.5 < pT < 7.0 GeV/c is presented and compared to next-to-leading order perturbative QCD (pQCD) calculations. Successful description of the unpolarized cross section above approximately 2 GeV/c suggests that pQCD is applicable in the interpretation of the asymmetry results in the relevant kinematic range.
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44
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Saturation of azimuthal anisotropy in Au + Au collisions at (square root)s(NN) = 62-200 GeV. PHYSICAL REVIEW LETTERS 2005; 94:232302. [PMID: 16090463 DOI: 10.1103/physrevlett.94.232302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2004] [Indexed: 05/03/2023]
Abstract
New measurements are presented for charged hadron azimuthal correlations at midrapidity in Au+Au collisions at (square root)s(NN) = 62.4 and 200 GeV. They are compared to earlier measurements obtained at (square root)s(NN) = 130 GeV and in Pb + Pb collisions at (square root)s(NN) = 17.2 GeV. Sizeable anisotropies are observed with centrality and transverse momentum (pT) dependence characteristic of elliptic flow (upsilon2). For a broad range of centralities, the observed magnitudes and trends of the differential anisotropy, upsilon2(pT), change very little over the collision energy range (square root)s(NN) = 62-200 GeV, indicating saturation of the excitation function for upsilon2 at these energies. Such a saturation may be indicative of the dominance of a very soft equation of state for (square root)s(NN) approximately 60-200 GeV.
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45
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Centrality dependence of direct photon production in (square root)S(NN) = 200 GeV Au + Au collisions. PHYSICAL REVIEW LETTERS 2005; 94:232301. [PMID: 16090462 DOI: 10.1103/physrevlett.94.232301] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2005] [Indexed: 05/03/2023]
Abstract
The first measurement of direct photons in Au + Au collisions at (square root)S(NN) = 200 GeV is presented. The direct photon signal is extracted as a function of the Au + Au collision centrality and compared to next-to-leading order perturbative quantum chromodynamics calculations. The direct photon yield is shown to scale with the number of nucleon-nucleon collisions for all centralities.
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46
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Deuteron and antideuteron production in Au+Au collisions at square root of s(NN)=200 GeV. PHYSICAL REVIEW LETTERS 2005; 94:122302. [PMID: 15903909 DOI: 10.1103/physrevlett.94.122302] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2004] [Indexed: 05/02/2023]
Abstract
The production of deuterons and antideuterons in the transverse momentum range 1.1<p(T)<4.3 GeV/c at midrapidity in Au+Au collisions at square root of s(NN)=200 GeV has been studied by the PHENIX experiment at RHIC. A coalescence analysis, comparing the deuteron and antideuteron spectra with that of proton and antiproton, has been performed. The coalescence probability is equal for both deuterons and antideuterons and it increases as a function of p(T), which is consistent with an expanding collision zone. Comparing (anti)proton yields, p /p=0.73+/-0.01, with (anti)deuteron yields, d /d=0.47+/-0.03, we estimate that n /n=0.64+/-0.04. The nucleon phase space density is estimated from the coalescence measurement.
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47
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Centrality dependence of charm production from a measurement of single electrons in Au+Au collisions at sqrt[s(NN)]=200 GeV. PHYSICAL REVIEW LETTERS 2005; 94:082301. [PMID: 15783878 DOI: 10.1103/physrevlett.94.082301] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2004] [Indexed: 05/24/2023]
Abstract
The PHENIX experiment has measured midrapidity transverse momentum spectra (0.4<p(T)<4.0 GeV/c) of single electrons as a function of centrality in Au+Au collisions at sqrt[s(NN)]=200 GeV. Contributions from photon conversions and Dalitz decays of light neutral mesons are measured by introducing a thin (1.7% X0) converter into the PHENIX acceptance and are statistically removed. The subtracted nonphotonic electron spectra are primarily due to the semileptonic decays of hadrons containing heavy quarks, mainly charm at lower p(T). For all centralities, the charm production cross section is found to scale with the nuclear overlap function, T(AA). For minimum-bias collisions the charm cross section per binary collision is N(cc )/T(AA)=622+/-57(stat)+/-160(syst) microb.
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48
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Nuclear modification factors for hadrons at forward and backward rapidities in deuteron-gold collisions at sqrt[s(NN)]=200 GeV. PHYSICAL REVIEW LETTERS 2005; 94:082302. [PMID: 15783879 DOI: 10.1103/physrevlett.94.082302] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2004] [Indexed: 05/24/2023]
Abstract
We report on charged hadron production in deuteron-gold reactions at sqrt[s(NN)]=200 GeV. Our measurements in the deuteron direction cover 1.4<eta<2.2, referred to as forward rapidity, and in the gold direction -2.0<eta<-1.4, referred to as backward rapidity, and a transverse momentum range p(T)=0.5-4.0 GeV/c. We compare the relative yields for different deuteron-gold collision centrality classes. We observe a suppression relative to binary collision scaling at forward rapidity, sensitive to low momentum fraction (x) partons in the gold nucleus, and an enhancement at backward rapidity, sensitive to high momentum fraction partons in the gold nucleus.
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49
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Double helicity asymmetry in inclusive midrapidity pi0 production for polarized p+p collisions at square root s = 200 GeV. PHYSICAL REVIEW LETTERS 2004; 93:202002. [PMID: 15600917 DOI: 10.1103/physrevlett.93.202002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2004] [Indexed: 05/24/2023]
Abstract
We present a measurement of the double longitudinal spin asymmetry in inclusive pi(0) production in polarized proton-proton collisions at sqrt[s]=200 GeV. The data were taken at the Relativistic Heavy Ion Collider with average beam polarizations of 0.27. The measurements are the first in a program to study the longitudinal spin structure of the proton, using strongly interacting probes, at collider energies. The asymmetry is presented for transverse momenta 1-5 GeV/c at midrapidity, where next-to-leading-order perturbative quantum chromodynamic (NLO pQCD) calculations well describe the unpolarized cross section. The observed asymmetry is small and is compared to a NLO pQCD calculation with a range of polarized gluon distributions.
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50
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Bose-Einstein correlations of charged pion pairs in Au + Au collisions at square root sNN = 200 GeV. PHYSICAL REVIEW LETTERS 2004; 93:152302. [PMID: 15524868 DOI: 10.1103/physrevlett.93.152302] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2004] [Indexed: 05/24/2023]
Abstract
Bose-Einstein correlations of identically charged pion pairs were measured by the PHENIX experiment at midrapidity in Au + Au collisions at square root s(NN)=200 GeV. The Bertsch-Pratt radius parameters were determined as a function of the transverse momentum of the pair and as a function of the centrality of the collision. Using the standard core-halo partial Coulomb fits, and a new parametrization which constrains the Coulomb fraction as determined from the unlike-sign pion correlation, the ratio R(out)/R(side) is within 0.8-1.1 for 0.25< <k(T)> <1.2 GeV/c. The centrality dependence of all radii is well described by a linear scaling in N(1/3)(part), and R(out)/R(side) for <k(T)> approximately 0.45 GeV/c is approximately constant at unity as a function of centrality.
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