[Application of ice-cold compression in infantile palatoplasty]

PURPOSE

To evaluate the clinical outcome of ice-cold compression in infantile palatoplasty under general anesthesia for oral swelling and pain relief.

METHODS

Eighty children with congenital cleft palate who underwent palatoplasty under general anesthesia were divided into 2 groups: experimental group and control group. Ice-cold compression was used in the experimental group before extubation, while 40 cases without ice-cold application was included as control. The patients were observed for the degree of swelling, pain and food intake after operation. SPSS13.0 software package was used for Student's test and Chi-square test.

RESULTS

Significant difference of swelling pain of wound and food intake between the 2 groups was found after operation.

CONCLUSIONS

Relief of swelling and pain using ice-cold compression can be obtained for infantile palatoplasty during the process of infantile palatoplasty.

Tracheostomy for infants requiring prolonged mechanical ventilation: 10 years' experience

BACKGROUND

Despite advances in care of critically ill neonates, extended mechanical ventilation and tracheostomy are sometimes required. Few studies focus on complications and clinical outcomes. Our aim was to provide long-term outcomes for a cohort of infants who required tracheostomy.

METHODS

This study is a retrospective review of 165 infants born between January 1, 2000 and December 31, 2010 who required tracheostomy and ventilator support. Children with complex congenital heart disease were excluded.

RESULTS

Median gestational age was 27 weeks (range 22-43), and birth weight was 820 g (range 360-4860). The number of male (53.9%) and female (46.1%) infants was similar (P = .312). Infants were divided into 2 groups based on birth weight ≤1000 g (A) and >1000 g (B). Group A: 87 (57.6%) infants; group B 64 (42.4%). Overall tracheostomy rate was 6.9% (87/1345) for group A versus 0.9% (64/6818) for B (P <.001). Group A had a longer time from intubation to positive pressure ventilation independence, 505 days (range 62-1287) vs 372 days (range 15-1270; P = .011). Infants who had >1 reason for tracheostomy comprised 78.8% of the sample; 69.1% of infants were discharged on ventilators. Birth weight did not affect time from tracheostomy to decannulation (P = .323). More group A infants were decannulated (P = .023). laryngotracheal reconstruction rate was 35.8%. Five-year survival was 89%. Group B had higher mortality (P = .033). 64.2% of infants had developmental delays; 74.2% had ≥2 comorbidities.

CONCLUSIONS

Tracheostomy rates were higher for extremely low birth weight infants than previously reported rates for all infants. Decannulation rates and laryngotracheal reconstruction rates were consistent with previous studies. Survival rates were high, but developmental delay and comorbidities were frequent.

[Epidemiological study of cytopenia among benzene-exposed workers and its influential factors]

OBJECTIVE

To evaluate the benzene exposure level and cytopenia among the benzene exposed workers in Shanghai, China and to analyze the influential factors for the health of benzene-exposed workers.

METHODS

A total of 3314 benzene-exposed workers, who were from 85 benzene-related enterprises selected by stratified random sampling based on enterprise sizes and industries, were included in the study. The time-weighted average (TWA) concentration of benzene in each workshop was measured by individual sampling and fixed point sampling, and the benzene exposure level in workshop was evaluated accordingly. The occupational health examination results and health status of benzene-exposed workers were collected.

RESULTS

The median of TW A concentrations of benzene was 0.3 mg/m3. The TWA concentrations measured at 7 ( 1.4%) of the 504 sampling points were above the safety limit. Of the 7 points, 3 were from large enterprises, 2 from medium enterprises, and 2 from small enterprises; 3 were from shipbuilding industry, 1 from chemical industry, and 3 from light industry. Of the 3314 benzene-exposed workers, 451 ( 13.6%) had cytopenia, including 339 males ( 339/2548, 13.3%) and 112 females ( 112/766, 14.6% ). There were significant differences in the incidence rates of leukopenia and neutropenia among the benzene-exposed workers of different sexes and ages (P<0.05); there were significant differences in the incidence rate of cytopenia among the benzene-exposed workers of different ages and working years ( P<0.05 ); there were significant differences in the incidence of neutropenia among the benzene exposed workers of different working years ( P<0.05).

CONCLUSION

Monitoring and intervention measures should be enhanced to protect the benzene-exposed workers in the large enterprises in shipbuilding industry and medium and private enterprises in chemical industry from occupational hazards.

Resource Utilization in Primary Repair of Cleft Lip

Objective

To determine national variations in resource utilization for primary repair of cleft lip, identify patient and institutional factors associated with high resource use, and estimate the current incidence of cleft lip in the United States.

Study Design

Retrospective analysis of a national, pediatric database (2009 Kids’ Inpatient Database [KID]).

Methods

Patients aged 1 year and younger were selected using international classification of disease codes for cleft lip and procedure codes for cleft lip repair. A number of demographic variables were analyzed, and hospital charges were considered as a measure of resource utilization.

Results

There were 1318 patients identified. The national incidence was 0.09%, with a male to female ratio of 1.8:1. Regional incidence varied from 0.07% (Northeast) to 0.10% (West). The mean age at surgery was 4.2 months. The average length of stay was 1.4 days. The national average hospital charge was $20,147, ranging from $14,635 (South) to $23,663 (West). Teaching hospitals charge an average of $9764 higher than nonteaching hospitals. The strongest predictor of charge was length of stay, increasing charge by $8102 for every additional hospital day ( P < .01).

Conclusion

Regional variations exist in resource utilization for primary cleft lip repair. Resource use is higher in the West and among teaching hospitals.

Cold-nuclear-matter effects on heavy-quark production in d+Au collisions at sqrt[S(NN)]=200 GeV

The PHENIX experiment has measured electrons and positrons at midrapidity from the decays of hadrons containing charm and bottom quarks produced in d+Au and p+p collisions at sqrt[S(NN)]=200 GeV in the transverse-momentum range 0.85 ≤ p(T)(e) ≤ 8.5 GeV/c. In central d+Au collisions, the nuclear modification factor R(dA) at 1.5<p(T)<5 GeV/c displays evidence of enhancement of these electrons, relative to those produced in p+p collisions, and shows that the mass-dependent Cronin enhancement observed at the Relativistic Heavy Ion Collider extends to the heavy D meson family. A comparison with the neutral-pion data suggests that the difference in cold-nuclear-matter effects on light- and heavy-flavor mesons could contribute to the observed differences between the π(0) and heavy-flavor-electron nuclear modification factors R(AA).

Evolution of π(0) suppression in Au+Au collisions from √(s(NN))=39 to 200 GeV

Neutral-pion π(0) spectra were measured at midrapidity (|y|<0.35) in Au+Au collisions at √(s(NN))=39 and 62.4 GeV and compared with earlier measurements at 200 GeV in a transverse-momentum range of 1<p(T)<10 GeV/c. The high-p(T) tail is well described by a power law in all cases, and the powers decrease significantly with decreasing center-of-mass energy. The change of powers is very similar to that observed in the corresponding spectra for p+p collisions. The nuclear modification factors (R(AA)) show significant suppression, with a distinct energy, centrality, and p(T) dependence. Above p(T)=7 GeV/c, R(AA) is similar for √(s(NN))=62.4 and 200 GeV at all centralities. Perturbative-quantum-chromodynamics calculations that describe R(AA) well at 200 GeV fail to describe the 39 GeV data, raising the possibility that, for the same p(T) region, the relative importance of initial-state effects and soft processes increases at lower energies. The p(T) range where π(0) spectra in central Au+Au collisions have the same power as in p+p collisions is ≈5 and 7 GeV/c for √(s(NN))=200 and 62.4 GeV, respectively. For the √(s(NN))=39 GeV data, it is not clear whether such a region is reached, and the x(T) dependence of the x(T)-scaling power-law exponent is very different from that observed in the √(s(NN))=62 and 200 GeV data, providing further evidence that initial-state effects and soft processes mask the in-medium suppression of hard-scattered partons to higher p(T) as the collision energy decreases.

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.

Observation of direct-photon collective flow in Au + Au collisions at √s(NN)] = 200 GeV

The second Fourier component v(2) of the azimuthal anisotropy with respect to the reaction plane is measured for direct photons at midrapidity and transverse momentum (p(T)) of 1-12 GeV/c in Au + Au collisions at √s(NN)] = 200 GeV. Previous measurements of this quantity for hadrons with p(T) < 6 GeV/c indicate that the medium behaves like a nearly perfect fluid, while for p(T) > 6 GeV/c a reduced anisotropy is interpreted in terms of a path-length dependence for parton energy loss. In this measurement with the PHENIX detector at the Relativistic Heavy Ion Collider we find that for p(T) > 4 GeV/c the anisotropy for direct photons is consistent with zero, which is as expected if the dominant source of direct photons is initial hard scattering. However, in the p(T) < 4 GeV/c region dominated by thermal photons, we find a substantial direct-photon v(2) comparable to that of hadrons, whereas model calculations for thermal photons in this kinematic region underpredict the observed v(2).

EGFR Inhibitor Therapy for Laryngeal Papillomatosis

Objective: 1) Study efficacy of epidermal growth factor receptor (EGFR) inhibitor adjuvant therapies in recurrent respiratory papillomatosis by comparing surgical treatment intervals and modified Derkay score prior to and following initiation of medical therapy. 2) Understand factors which affect patient responses to EGFR inhibitor adjuvant therapy.

Method: We performed a retrospective case series of 4 pediatric patients with life threatening recurrent respiratory papillomatosis. Patient charts were reviewed to determine time between surgical procedures and Derkay severity score during operative procedures prior to and following initiation of EGFR inhibitors.

Results: Prior to therapy many of the patients’ median Derkay scores were worsening. Following initiation of EGFR inhibitor therapy, the median Derkay score decreased for all 4 patients. In one patient, in whom a limited response was observed, there was no significant change in the time interval between surgical procedures. In 2 patients there was a greater than 25% increase and in the remaining case the interval between procedures more than doubled the original time.

Conclusion: EGFR inhibitors appear to be a potential effective adjunct therapy for the treatment of recurrent respiratory papillomatosis. Beneficial results were observed in 3 patients as evidenced by Derkay score and interval between operative interventions. One patient exhibited no response to the EGFR inhibitors for reasons which are being investigated.

Resource Utilization in Primary Cleft Lip Repair

Objective: 1) To estimate the current incidence of cleft lip in the United States and whether any regional variations exist. 2) To determine national variations in resource utilization in the primary repair of cleft lip and identify patient and institutional factors associated with increased resource use.

Method: Retrospective analysis of a national, pediatric database (2009 Kids Inpatient Database (KID)). Patients aged 1 year and below were selected using diagnoses codes for cleft lip and procedure codes for lip repair. A number of demographic variables were analyzed and hospital charges were considered as a measure of resource utilization.

Results: There were 1318 patients identified. Overall incidence nationwide was 0.09% with male to female ratio of 1.8:1. Regional incidence varied from 0.07% (Northeast) to 0.10% (West). The mean age at surgery was 4.2 months. The average length of stay was 1.4 days, with minimal regional variation. The average total charge nationwide was $20,147, ranging from $14,635 (South) to $23,663 (West). Average charge in a teaching institution was $9764 higher than for nonteaching institutions. The strongest predictor of charge was length of stay, increasing by $8102 for every additional hospital day ( P < .01).

Conclusion: Regional variations exist in resource utilization for primary cleft lip repair. Resource use is higher in the West and among teaching institutions. These results show that whiles length of stay is a key determinant of charge; other factors also play a role.

Nondepressed linear skull fractures in children younger than 2 years: is computed tomography always necessary?

BACKGROUND

Current recommendations are that young children with a skull fracture following head injury undergo computed tomography (CT) examination of their head to exclude significant intracranial injury. Recent reports, however, have raised concern that radiation exposure from CT scanning may cause malignancies.

OBJECTIVE

To estimate the proportion of children with nondisplaced linear skull fractures who have clinically significant intracranial injury.

METHODS

Retrospective review of patients younger than 2 years who presented to an emergency department and received a diagnosis of skull fracture.

RESULTS

Ninety-two patients met the criteria for inclusion in the study; all had a head CT scan performed. None suffered a clinically significant intracranial injury.

CONCLUSION

Observation, rather than CT, may be a reasonable management option for head-injured children younger than 2 years who have a nondisplaced linear skull fracture on plain radiography but no clinical signs of intracranial injury.

Analysis on the reactivity of five subunits of antigen B family in serodiagnosis of echinococcosis

In this study, the reactivity and differences of five subunits of echinococcus antigen B (AgB) family, recognizing specific antibodies in echinococcosis patient serum, were analyzed. Eight recombinant subunit antigens from Echinococcus granulosus (EgAgB1-EgAgB4) and Echinococcus multilocularis (EmAgB1-EmAgB3 and EmAgB5) were tested by ELISA using a panel of 243 serum samples collected from cystic echinococcosis (CE), alveolar echinococcosis (AE), cysticercosis (CC) patients and clinically normal individuals (NH). The results showed that the diagnostic sensitivity of the subunits for CE sera were 83.06%, 62.90%, 29.03%, 75.81% and 41.13%, and the specificities were 73.95%, 72.27%, 76.47%, 73.11% and 85.71%, respectively. The reactivity of three paralogous subunits, EgAgB1, EgAgB2 and EgAgB3 from E. granulosus and EmAgB1, EmAgB2 and EmAgB3 from E. multilocularis were compared by serological assay. All of the orthologous subunits showed no statistical difference (P>0.05) in detecting CE and AE sera; it revealed that the reactive epitopes may be similar between the orthologous subunits. In a total of 124 CE sera, the positive recognition rate by EgAgB1 was the highest (103/124), yet cocktail subunit antigens may detect even more positives from 100/124 to 112/124 using different subunit combinations. IgG4 subclass was the predominant antibody in reacting with subunit antigens. To conclude, the epitopes of orthologous AgB subunits from E. granulosus and E. multilocularis that recognize specific antibodies may be similar. The paralogous subunits EgAgB1, EgAgB2 and EgAgB4 were the main reactive subunit in sera detection and may have utility as echinococcosis diagnostics, with EgAgB1 possessing the greatest potential. Cocktail subunits may improve the positive detection rate.

Incidental sinusitis in a pediatric intensive care unit

OBJECTIVE

Intubation is a risk factor for nosocomial sinusitis in adult intensive care patients. Sinusitis in intubated adults can be an occult cause of fever. In children, nasal intubation may increase the risk of sinusitis. No pediatric study has determined the frequency of nosocomial sinusitis in the pediatric intensive care unit setting. We hypothesized that within a subset of patients who had head computed tomography imaging 1) the incidental frequency of sinusitis in pediatric intensive care unit patients exceeds the frequency in non-pediatric intensive care unit patients, 2) the frequency of sinusitis is greater in pediatric intensive care unit patients with a tube (nasotracheal, nasogastric, orotracheal, or orogastric) compared to those without a tube, and 3) nasal tubes confer an increased risk for sinusitis over oral tubes.

DESIGN

Retrospective chart review.

SETTING

Independent not-for-profit pediatric healthcare system.

PATIENTS

Pediatric intensive care unit and non-pediatric intensive care unit (inpatients hospitalized on medical-surgical wards) patients referred for head computed tomography.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Computed tomography images were scored using the Lund-MacKay staging system. Sinusitis was defined as a Lund-MacKay score ≥5. A total of 596 patients were studied, 395 (66.3%) in the pediatric intensive care unit. A total of 154 (44.3%) pediatric intensive care unit vs. 54 (26.9%) non-pediatric intensive care unit patients had sinusitis (p < .001). A total of 102 of 147 (69.4%) pediatric intensive care unit patients with a tube present had sinusitis vs. 73 of 248 (29.4%) patients without a tube present (p < .001). There was no difference in sinusitis based on tube location (p = .472). Of patients with sinusitis, 51.3% (81 of 158) compared to 39.4% (89 of 226) were febrile within 48 hrs of imaging (p = .021). A younger age or the presence of a tube increased the probability of sinusitis (p < .001).

CONCLUSIONS

A total of 44.3% of our pediatric intensive care unit patients imaged for reasons other than evaluation for sinus disease had evidence of sinusitis, and 51.3% of these had fever. These findings raise the concern that sinusitis in pediatric intensive care unit patients is common and should be considered in the differential diagnosis of fever in pediatric intensive care unit patients.

Measurements of higher order flow harmonics in Au+Au collisions at √s(NN)=200 GeV

Flow coefficients ν(n) for n=2, 3, 4, characterizing the anisotropic collective flow in Au+Au collisions at √s(NN)=200 GeV, are measured relative to event planes Ψ(n), determined at large rapidity. We report ν(n) as a function of transverse momentum and collision centrality, and study the correlations among the event planes of different order n. The ν(n) are well described by hydrodynamic models which employ a Glauber Monte Carlo initial state geometry with fluctuations, providing additional constraining power on the interplay between initial conditions and the effects of viscosity as the system evolves. This new constraint can serve to improve the precision of the extracted shear viscosity to entropy density ratio η/s.

Analysis of binding interaction between (-)-epigallocatechin (EGC) and β-lactoglobulin by multi-spectroscopic method

The binding interaction between (-)-epigallocatechin (EGC) with bovine β-lactoglobulin (βLG) was investigated by fluorescence, circular dichroism (CD) and Fourier transform infrared (FTIR) spectroscopy methods. The binding parameters were determined by Stern-Volmer equation and the thermodynamic parameters were calculated according to the van't Hoff equation. The results suggested that βLG was bound by EGC, which resulted in change of native conformation of βLG. van der Waals interactions and hydrogen bonding probably played major roles in the binding process. Our study is helpful for further elucidation of binding interactions between catechins with milk proteins, which would contribute to the development of novel milk products.

Suppression of back-to-back hadron pairs at forward rapidity in d+Au collisions at √s(NN)=200 GeV

Back-to-back hadron pair yields in d+Au and p+p collisions at √s(NN)=200 GeV were measured with the PHENIX detector at the Relativistic Heavy Ion Collider. Rapidity separated hadron pairs were detected with the trigger hadron at pseudorapidity |η|<0.35 and the associated hadron at forward rapidity (deuteron direction, 3.0<η<3.8). Pairs were also detected with both hadrons measured at forward rapidity; in this case, the yield of back-to-back hadron pairs in d+Au collisions with small impact parameters is observed to be suppressed by a factor of 10 relative to p+p collisions. The kinematics of these pairs is expected to probe partons in the Au nucleus with a low fraction x of the nucleon momenta, where the gluon densities rise sharply. The observed suppression as a function of nuclear thickness, p(T), and η points to cold nuclear matter effects arising at high parton densities.

Cold nuclear matter effects on J/ψ yields as a function of rapidity and nuclear geometry in d+A collisions at sqrt[s(NN)]=200 GeV

We present measurements of J/ψ yields in d+Au collisions at sqrt[s(NN)]=200  GeV recorded by the PHENIX experiment and compare them with yields in p+p collisions at the same energy per nucleon-nucleon collision. The measurements cover a large kinematic range in J/ψ rapidity (-2.2<y<2.4) with high statistical precision and are compared with two theoretical models: one with nuclear shadowing combined with final state breakup and one with coherent gluon saturation effects. In order to remove model dependent systematic uncertainties we also compare the data to a simple geometric model. The forward rapidity data are inconsistent with nuclear modifications that are linear or exponential in the density weighted longitudinal thickness, such as those from the final state breakup of the bound state.

Stability of lyophilized human platelets loaded with small molecule carbohydrates

Long-term preservation of platelets is a great challenge for blood transfusion centers, due to the required narrow storage temperature arange (22 ± 2 degree C). Short shelf life and potential bacterial growth often lead to the shortage of high-quality platelets. Freeze-dried preservation is thus believed to be a potential solution for long-term platelet storage without losing the hemostasis function. Here we report a new platelet preservation method, which uses small molecule carbohydrates to extend storage time and to maintain platelet function. The activities of lyophilized platelets that were stabilized with small molecule carbohydrate (e.g., cell viability, mean platelet volume, activation characteristics, and aggregation kinetics) were maintained after storage of 30, 60, and 90 days at room temperature, 4 degree C, and -20 degree C. The recovery of freeze-dried platelets was 87 percent in comparison to fresh platelets. The mean platelet volume of rehydrated platelets increased (from 6.8 fl to 8.0 fl). About 40 percent of rehydrated platelets was in the early-activated stage (PCA-1 positive) and 30 percent was in the terminal-activated stage (CD62P positive). The cell viability was about 60 percent as measured with CMFDA vital probes. The aggregation rate of rehydrated platelets after 90-day storage was similar to fresh platelets stored at 22 degree C ± 2 degree C.

Cross section and parity-violating spin asymmetries of W± boson production in polarized p + p collisions at sqrt[s] = 500 GeV

Large parity-violating longitudinal single-spin asymmetries A(L)(e+) = -0.86(-0.14) (+0.30) and A(L)(e-) = 0.88(-0.71) (+0.12) are observed for inclusive high transverse momentum electrons and positrons in polarized p+p collisions at a center-of-mass energy of sqrt[s] = 500 GeV with the PHENIX detector at RHIC. These e± come mainly from the decay of W± and Z0 bosons, and their asymmetries directly demonstrate parity violation in the couplings of the W± to the light quarks. The observed electron and positron yields were used to estimate W± boson production cross sections for the e± channels of σ(pp → W+ X) × BR(W+ → e+ ν(e)) = 144.1 ± 21.2(stat)(-10.3) (+3.4) (syst) ± 21.6(norm)  pb, and σ(pp → W- X) × BR(W- → e- ν[over ¯](e)) = 31.7 ± 12.1(stat)(-8.2) (+10.1) (syst) ± 4.8(norm)  pb.

Development and validation of a capillary electrophoresis method for the enantiomeric purity determination of RS86017 using experimental design

A selective capillary electrophoresis method for determination of enantiomeric purity of RS86017, a new antiarrhythmic agent with two chiral centers, was developed and validated using sulfobutyl ether-β-cyclodextrin as chiral selector. The concentration of the chiral selector and organic modifier, pH of background electrolyte (BGE), capillary temperature, and applied voltage were systematically optimized by using orthogonal design and concentration of chiral selector was further optimized. The optimal conditions included 25mM phosphate buffer at pH 8.0, containing 28mg/mL sulfobutyl ether-β-cyclodextrin and 20% acetonitrile as running buffer, an applied voltage of 22kV, and a temperature of 20°C. The detection wavelength was 206nm. The obtained method was capable of separating RS86017 from its potential chiral impurities, the S,R-enantiomer, the R,R-diastereomer and the S,S-diastereomer with a short analysis time of 10min. The separation was validated with respect to its selectivity, repeatability, linearity, precision, accuracy, limits of detection (LOD), limits of quantitation (LOQ) and robustness testing. The LODs and LOQs were 0.8μg/mL and 2.5μg/mL for all isomers of RS86017, respectively. Finally, the method was used to investigate the chiral purity of RS86017 in bulk samples.

Azimuthal anisotropy of π⁰ production in Au+Au collisions at sqrt((s)NN)=200 GeV: path-length dependence of jet quenching and the role of initial geometry

We have measured the azimuthal anisotropy of π⁰ production for 1<p(T)<18  GeV/c for Au+Au collisions at sqrt((s)NN)=200  GeV. The observed anisotropy shows a gradual decrease for 3≲p(T)≲7-10  GeV/c, but remains positive beyond 10  GeV/c. The magnitude of this anisotropy is underpredicted, up to at least ∼10  GeV/c, by current perturbative QCD (PQCD) energy-loss model calculations. An estimate of the increase in anisotropy expected from initial-geometry modification due to gluon saturation effects and fluctuations is insufficient to account for this discrepancy. Calculations that implement a path-length dependence steeper than what is implied by current PQCD energy-loss models show reasonable agreement with the data.

Elliptic and hexadecapole flow of charged hadrons in Au+Au collisions at sq.rt(s(NN))=200 GeV

Differential measurements of the elliptic (v(2)) and hexadecapole (v(4)) Fourier flow coefficients are reported for charged hadrons as a function of transverse momentum (p(T)) and collision centrality or number of participant nucleons (N(part)) for Au+Au collisions at sq.rt(s(NN))=200  GeV. The v(2,4) measurements at pseudorapidity |η|≤0.35, obtained with four separate reaction-plane detectors positioned in the range 1.0<|η|<3.9, show good agreement, indicating the absence of significant Δη-dependent nonflow correlations. Sizable values for v(4)(p(T)) are observed with a ratio v(4)(p(T),N(part))/v(2)(2)(p(T),N(part))≈0.8 for 50≲N(part)≲200, which is compatible with the combined effects of a finite viscosity and initial eccentricity fluctuations. For N(part)≳200 this ratio increases up to 1.7 in the most central collisions.

Transition in yield and azimuthal shape modification in dihadron correlations in relativistic heavy ion collisions

Hard-scattered parton probes produced in collisions of large nuclei indicate large partonic energy loss, possibly with collective produced-medium response to the lost energy. We present measurements of π^{0} trigger particles at transverse momenta p{T}{t}=4-12  GeV/c and associated charged hadrons (p{T}{a}=0.5-7  GeV/c) vs relative azimuthal angle Δϕ in Au+Au and p+p collisions at sqrt[s{NN}]=200  GeV. The Au+Au distribution at low p{T}{a}, whose shape has been interpreted as a medium effect, is modified for p{T}{t}<7  GeV/c. At higher p{T}{t}, the data are consistent with unmodified or very weakly modified shapes, even for the lowest measured p{T}{a}, which quantitatively challenges some medium response models. The associated yield of hadrons opposing the trigger particle in Au+Au relative to p+p (I{AA}) is suppressed at high p{T} (I{AA}≈0.35-0.5), but less than for inclusive suppression (R{AA}≈0.2).