Late selective termination in dichorionic twins: comparing late second and third trimester procedures

RESEARCH QUESTION

Do perinatal outcomes of selective termination performed in the late second versus third trimester differ and what risk factors are associated with subsequent preterm birth?

DESIGN

This is a retrospective cohort study of late selective terminations performed in dichorionic twins between 2009 and 2021. Perinatal outcomes were compared between two groups: group A, late second trimester (20.2 to 24.2 weeks, n = 26), and group B, third trimester (≥28.2 weeks, n = 55) selective terminations. Univariate and multivariate analyses were conducted to identify factors associated with post-procedure preterm birth.

RESULTS

In total, 81 dichorionic twin pregnancies were included. There were no pregnancy losses but 16% (13/81) of cases experienced complications. Group A had a higher median birthweight centile (36.5th versus 15th centile, P = 0.002) and lower rates of intrauterine growth restriction (IUGR) and Caesarean delivery (11.5% versus 32.7%, P = 0.04; and 26.9% versus 61.8%, P = 0.003) than group B. Preterm birth rates were similar (46.2% versus 63.6%, P = 0.15). Multiple regression revealed that reduction of the presenting twin and cervical length ≤35 mm were independently associated with post-procedure preterm birth (odds ratio [OR] 8.7, P = 0.001, 95% confidence interval [CI] 2.5-29.8; OR 3.8, P = 0.015, 95% CI 1.3-11).

CONCLUSIONS

Late second trimester selective termination is associated with a higher birthweight centile and lower rates of IUGR and Caesarean delivery, compared with third trimester selective termination. Cervical length 35 mm or less and reduction of the presenting twin are independent risk factors for post-procedural preterm birth. These findings may help determine the optimal time to perform a late selective termination.

Dynamic esophageal patency assessment: an effective method for prenatally diagnosing esophageal atresia

BACKGROUND

Esophageal atresia is a major anomaly with a low prenatal detection rate. We propose a sonographic method termed dynamic esophageal patency assessment.

OBJECTIVE

This study aimed to assess the feasibility and performance of the dynamic esophageal patency assessment in a high-risk population.

STUDY DESIGN

A prospective study was conducted in a single tertiary fetal ultrasound unit for 12 months. The study group included pregnant women referred for a targeted scan because of one or more of the following: (1) polyhydramnios; (2) small or absent stomach; (3) vertebral, anal atresia, cardiac, tracheoesophageal fistula, renal, and limb abnormalities; (4) first-degree relative with esophageal atresia; and (5) genetic mutation associated with esophageal atresia. In addition to dynamic esophageal patency assessment, a comprehensive anomaly scan was carried out. The fetal esophagus was observed during swallowing. Cases that demonstrated uninterrupted fluid propagation through the esophagus were classified as normal. Cases that demonstrated interrupted fluid propagation, with the formation of a pouch, were classified as abnormal. Cases with unclear visualization of the esophagus or cases that failed to demonstrate either fluid propagation or a pouch were classified as undetermined. Dynamic esophageal patency assessment results were compared with postnatal findings, considered "gold standard." Test performance indices and intra- and interobserver agreements were calculated.

RESULTS

For 12 months, 130 patients were recruited, and 132 fetuses were scanned. The median gestational age (interquartile range) at the time of scan was 31.4 weeks (29.0-35.3). Of 132 fetuses enrolled, 123 (93.2%) were normal, 8 (6%) were abnormal, and 1 (0.8%) was undetermined. Excluded from test performance analysis were 3 cases that were terminated without postmortem autopsy (1 was abnormal and 2 were normal), and a fourth case was excluded as it was classified as undetermined. The detection rate of esophageal atresia was 100%, with no false-positive or false-negative case. Sensitivity, specificity, and positive and negative predictive values of the dynamic esophageal patency assessment were 100%. The Kappa coefficient was 1 for both inter- and intraobserver agreements (P<.0001). The median time (interquartile range) required to complete the dynamic esophageal patency assessment was 6.00 minutes (3.00-13.25).

CONCLUSION

The dynamic esophageal patency assessment is a feasible and highly effective method of ascertaining an intact esophagus and detecting esophageal atresia in suspected cases.

Do Serial Sonographic Assessments of Fetuses with Isolated Congenital Diaphragmatic Hernia Help Us Predict Survival?

OBJECTIVE

The aim of this study was to assess the ability of serial prenatal sonographic measurements, and specifically changes in the observed-to-expected lung-to-head ratio (O/E LHR) throughout gestation and to predict survival in congenital diaphragmatic hernia (CDH).

METHODS

Retrospective study of CDH fetuses evaluated prenatally and treated postnatally in a single tertiary center, 2008-2020. Sonographic evaluations included side of herniation, liver involvement, and O/E LHR. All data were calculated to assess ability to predict survival.

RESULTS

Overall, 94 fetuses were evaluated prenatally and delivered in our medical center. Among them, 75 had isolated CDH and 19 nonisolated. CDH was categorized as left (n = 76; 80.8%), right (n = 16; 17.0%), or bilateral (n = 2; 2.2%). Overall perinatal survival rate was 57% for all live-born infants, 68% in isolated CDH, and 40% in nonisolated (excluding 2 cases that underwent fetoscopic endoluminal tracheal occlusion and did not survive). The O/E LHR was lower in cases with perinatal death compared to survivors. In cases with multiple evaluations, the minimal O/E LHR was the most accurate predictor of survival and need for perinatal extracorporeal membrane oxygenation (ECMO) support. This remained significant when excluding twin pregnancies or when evaluating only isolated left CDH. In addition to disease severity, the side of herniation and liver position was associated with preoperative mortality.

CONCLUSION

O/E LHR is associated with perinatal survival. In cases with multiple evaluations, the minimal O/E LHR is the most accurate and significant predictor of perinatal mortality and need for ECMO support.

Congenital Cytomegalovirus Infection Following Second and Third Trimester Maternal Infection Is Associated With Mild Childhood Adverse Outcome Not Predicted by Prenatal Imaging

BACKGROUND

While it is clear that first trimester congenital cytomegalovirus (CMV) infection can lead to serious neonatal and childhood adverse outcome, the extent of the effect of second and third trimester congenital CMV infection is still unclear. Our aim was to study the short- and long-term outcomes following second and third trimester infection and to evaluate the contribution of prenatal imaging in a prospective cohort.

METHODS

We studied pregnant women with primary CMV infection in the second and third trimesters, as diagnosed by well-dated seroconversion, and proof of vertical CMV transmission. All patients underwent serial prenatal ultrasound (US) and most of them fetal magnetic resonance imaging (MRI). Follow-up information was obtained from hospital charts and by telephone interviews with parents.

RESULTS

Primary CMV infection occurred in 135 patients, 107 and 28 with second and third trimester infection, respectively. The incidence proportion of composite outcome (hearing loss or neurodevelopmental impairment) following second trimester infection was 7% (7/100, after excluding cases that were terminated) with a 3% incidence of partial unilateral sensory neural hearing loss and a 5% incidence of minor neurodevelopmental abnormalities, including slight verbal and motor delay. Following third trimester infection, there was one case of a very mild motor delay. The incidence proportion of abnormal prenatal findings on US or MRI was not significantly correlated to hearing loss or neurodevelopmental abnormalities.

CONCLUSIONS

Second trimester infection is associated with a slight risk of developing mild childhood sequelae, mostly partial unilateral hearing loss, which may develop late in childhood. Prenatal imaging failed to predict the development of childhood adverse outcome.

Fetal esophageal imaging: Early pregnancy as a window of opportunity

OBJECTIVE

To describe the sonographic appearance of the fetal esophagus during early pregnancy and evaluate the feasibility of imaging the entire esophageal length. In addition, we present a case of disrupted esophageal continuity, subsequently diagnosed with esophageal atresia (EA).

METHODS

A prospective observational study of 145 patients. During the early second trimester anomaly scan performed at 12-17 weeks' gestation the entire esophagus was captured in a single sonographic image at the midsagittal plane (one shot technique). Postnatal follow-up of esophageal patency included review of medical records and telephone interviews.

RESULTS

Complete visualization of the esophagus (neck to diaphragm) was possible in 144 cases. In 88% of cases the esophagus was demonstrated by transvaginal approach. The time required to obtain the desired view of the esophagus, once the fetus was in an optimal position, was on average 13 s (range: 5-30 s). In one case at 15 weeks' gestation, the cervical segment of the esophagus was demonstrated while the lower thoracic segment was not identified. Subsequently EA was diagnosed.

CONCLUSIONS

It is feasible to demonstrate the entire esophagus during early second trimester anomaly scan. An early second trimester anomaly scan may serve as a window of opportunity for EA screening.

The role of ICSI vs. conventional IVF for patients with advanced maternal age-a randomized controlled trial

OBJECTIVES

This study aimed to evaluate the role of intracytoplasmic sperm injection (ICSI) in the treatment of non-male factor infertile patients aged ≥ 39.

METHODS

This is a single-center, prospective, randomized controlled clinical trial, between March 2018 and December 2019. Sixty-nine patients were recruited, and sixty patients participated in the study. Their ovaries were randomized prior to the beginning of the ovarian stimulation: the oocytes from one side (n = 257) were allocated to the ICSI (ICSI arm), while those of the contralateral side (n = 258) were allocated to conventional insemination (IVF arm). The fertilization rate per oocyte retrieved, number of zygotes (2PN), and cleavage-stage embryos were assessed and compared between the two study groups.

RESULTS

The average number of zygotes (3.1 vs. 2.7 p = 0.45), the fertilization rate (72.4% vs. 65.1% p = 0.38), the average number of cleavage-stage (2.8 vs. 2.4 p = 0.29), and the average top-quality embryos (TQE) cleavage-stage embryos (1.7 vs. 1.6 p = 0.94) were comparable between the two groups. The TQE rate per randomized oocyte (41.2% vs. 41% p = 0.8) was also similar in both groups.

CONCLUSIONS

ICSI does not improve the reproductive outcomes of advanced-age patients undergoing conventional insemination for non-male factor infertility.

TRIAL REGISTRATION

NCT03370068.

Beam Energy and Centrality Dependence of Direct-Photon Emission from Ultrarelativistic Heavy-Ion Collisions

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.

A false-carrier state for the c.579G>A mutation in the NCF1 gene in Ashkenazi Jews

BACKGROUND

Mutations in the NCF1 gene that encodes p47^phox, a subunit of the NADPH oxidase complex, cause chronic granulomatous disease (CGD). In Kavkazi Jews, a c.579G>A (p.Trp193Ter) mutation in NCF1 is frequently found, leading to CGD. The same mutation is found in about 1% of Ashkenazi Jews, although Ashkenazi CGD patients with this mutation have never been described.

METHODS

We used Sanger sequencing, multiplex ligation-dependent probe amplification (MLPA), gene scan analysis and Ion Torrent Next Generation Sequencing for genetic analysis, and measured NADPH oxidase activity and p47^phox expression.

RESULTS

In an Ashkenazi couple expecting a baby, both parents were found to be heterozygotes for this mutation, as was the fetus. However, segregation analysis in the extended family was consistent with the fetus inheriting both carrier alleles from the parents. MLPA indicated four complete NCF1 genes in the fetus and three in each parent. Gene sequencing confirmed these results. Analysis of fetal leucocytes obtained by cordocentesis revealed substantial oxidase activity with three different assays, which was confirmed after birth. In six additional Ashkenazi carriers of the NCF1 c.579G>A mutation, we found five individuals with three complete NCF1 genes of which one was mutated (like the parents), and one individual with in addition a fusion gene of NCF1 with a pseudogene.

CONCLUSION

These results point to the existence of a 'false-carrier' state in Ashkenazi Jews and have wide implications regarding pre-pregnancy screening in this and other population groups.

Astronomical time-of-flight photon speedometer

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.

Measurements of Elliptic and Triangular Flow in High-Multiplicity 3He+Au Collisions at √(s(NN))=200 GeV

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.

Medium modification of jet fragmentation in Au+Au collisions at √[s(NN)]=200 GeV measured in direct photon-hadron correlations

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.

Measurement of direct photons in Au+Au collisions at √(s(NN))=200 GeV

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.

Primer-induced in situ hybridization to plant chromosomes

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.

Detection of ribosomal DNA sites in lentil and chickpea by fluorescent in situ hybridization

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.

Detection of interchromosomal translocations within the Triticeae by RFLP analysis

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.

Catastrophic decline of a top carnivore in the gulf of california rocky intertidal zone

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.

Metabolic event involved in the bactericidal activity of normal mouse macrophages

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.

Enhanced production of direct photons in Au + Au collisions at square root(S(NN)) = 200 GeV and implications for the initial temperature

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.

Charged Kaon interferometric probes of space-time evolution in Au+Au collisions at sqrt[S(NN)]=200 GeV

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.

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

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.

MicroRNA-221/222 confers tamoxifen resistance in breast cancer by targeting p27(kip1)

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.&#x2028; 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.&#x2028; 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.&#x2028; 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.

Suppression pattern of neutral pions at high transverse momentum in Au + Au collisions at sqrt[sNN]=200 GeV and constraints on medium transport coefficients

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.

Onset of pi(0) suppression studied in Cu+Cu collisions at sqrt S NN=22.4, 62.4, and 200 GeV

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.

J/psi production in sqrt s_NN=200 GeV Cu+Cu collisions

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).

Particle-species dependent modification of jet-induced correlations in Au+Au collisions at sqrt[s_{NN}]=200 GeV

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.

Source breakup dynamics in Au + Au collisions at sqrt[s(NN)]=200 GeV via three-dimensional two-pion source imaging

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.

Elliptic flow for phi mesons and (anti)deuterons in Au+Au collisions at square root of sNN=200 GeV

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.

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

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.

J/psi production versus transverse momentum and rapidity in p+p collisions at square root s=200 GeV

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.

J/psi production versus centrality, transverse momentum, and rapidity in Au+Au collisions at square root sNN=200 GeV

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.

Scaling properties of azimuthal anisotropy in Au+Au and Cu+Cu Collisions at sqrt[s NN]=200 GeV

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.

Evidence for a long-range component in the pion emission source in Au+Au collisions at sqrt sNN=200 GeV

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.

Measurement of direct photon production in p+p collisions at sqrt[s] = 200 GeV

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.

Measurement of high-pT single electrons from heavy-flavor decays in p + p collisions at square root of s = 200 GeV

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.

Dense-medium modifications to jet-induced hadron pair distributions in Au+Au collisions at sqrt s NN=200 GeV

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.

Azimuthal angle correlations for rapidity separated Hadron pairs in d+Au collisions at square root of sNN=200 GeV

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.

Common suppression pattern of eta and pi0 mesons at high transverse momentum in Au + Au collisions at square root S(NN) = 200 GeV

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.

Single electrons from heavy-flavor decays in collisions at

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].

Measurement of identified and inclusive photon second-harmonic parameter and implications for direct photon production in [FORMULA: SEE TEXT] Au+Au

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.

Nuclear modification of electron spectra and implications for heavy quark energy loss in Au+Au collisions at [FORMULA: SEE TEXT]

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.

J/psi production and nuclear effects for d + Au and p + p collisions at square root of S(NN) = 200 GeV

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.

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

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.

Saturation of azimuthal anisotropy in Au + Au collisions at (square root)s(NN) = 62-200 GeV

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.

Centrality dependence of direct photon production in (square root)S(NN) = 200 GeV Au + Au collisions

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.

Deuteron and antideuteron production in Au+Au collisions at square root of s(NN)=200 GeV

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.

Centrality dependence of charm production from a measurement of single electrons in Au+Au collisions at sqrt[s(NN)]=200 GeV

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.

Nuclear modification factors for hadrons at forward and backward rapidities in deuteron-gold collisions at sqrt[s(NN)]=200 GeV

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.

Double helicity asymmetry in inclusive midrapidity pi0 production for polarized p+p collisions at square root s = 200 GeV

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.