Erratum: Evolution of π

This corrects the article DOI: 10.1103/PhysRevLett.109.152301.

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

The PHENIX collaboration presents first measurements of low-momentum (0.41 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.

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.

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

Three-particle coincidence of the long range pseudorapidity correlation in high energy nucleus-nucleus collisions.

We report the first three-particle coincidence measurement in pseudorapidity (Δη) between a high transverse momentum (p⊥) trigger particle and two lower p⊥ associated particles within azimuth |Δϕ|<0.7 in square root of s(NN)=200 GeV d+Au and Au+Au collisions. Charge ordering properties are exploited to separate the jetlike component and the ridge (long range Δη correlation). The results indicate that the correlation of ridge particles are uniform not only with respect to the trigger particle but also between themselves event by event in our measured Δη. In addition, the production of the ridge appears to be uncorrelated to the presence of the narrow jetlike component.

Higher moments of net proton multiplicity distributions at RHIC.

We report the first measurements of the kurtosis (κ), skewness (S), and variance (σ2) of net-proton multiplicity (Np-Np) distributions at midrapidity for Au+Au collisions at square root of s(NN)=19.6, 62.4, and 200 GeV corresponding to baryon chemical potentials (µB) between 200 and 20 MeV. Our measurements of the products κσ2 and Sσ, which can be related to theoretical calculations sensitive to baryon number susceptibilities and long-range correlations, are constant as functions of collision centrality. We compare these products with results from lattice QCD and various models without a critical point and study the square root of s(NN) dependence of κσ2. From the measurements at the three beam energies, we find no evidence for a critical point in the QCD phase diagram for µB below 200 MeV.

Measurement of the bottom quark contribution to nonphotonic electron production in p + p collisions at √s=200 GeV.

The contribution of B meson decays to nonphotonic electrons, which are mainly produced by the semileptonic decays of heavy-flavor mesons, in p + p collisions at √s=200 GeV has been measured using azimuthal correlations between nonphotonic electrons and hadrons. The extracted B decay contribution is approximately 50% at a transverse momentum of pT≥5 GeV/c. These measurements constrain the nuclear modification factor for electrons from B and D meson decays. The result indicates that B meson production in heavy ion collisions is also suppressed at high pT.

Azimuthal charged-particle correlations and possible local strong parity violation.

Parity-odd domains, corresponding to nontrivial topological solutions of the QCD vacuum, might be created during relativistic heavy-ion collisions. These domains are predicted to lead to charge separation of quarks along the system's orbital momentum axis. We investigate a three-particle azimuthal correlator which is a P even observable, but directly sensitive to the charge separation effect. We report measurements of charged hadrons near center-of-mass rapidity with this observable in Au + Au and Cu + Cu collisions at square root of s(NN) = 200 GeV using the STAR detector. A signal consistent with several expectations from the theory is detected. We discuss possible contributions from other effects that are not related to parity violation.

Growth of long range forward-backward multiplicity correlations with centrality in Au + Au collisions at square root of sNN = 200 GeV.

Forward-backward multiplicity correlation strengths have been measured with the STAR detector for Au + Au and p + p collisions at square root of s(NN) = 200 GeV. Strong short- and long-range correlations (LRC) are seen in central Au + Au collisions. The magnitude of these correlations decrease with decreasing centrality until only short-range correlations are observed in peripheral Au + Au collisions. Both the dual parton model (DPM) and the color glass condensate (CGC) predict the existence of the long-range correlations. In the DPM, the fluctuation in the number of elementary (parton) inelastic collisions produces the LRC. In the CGC, longitudinal color flux tubes generate the LRC. The data are in qualitative agreement with the predictions of the DPM and indicate the presence of multiple parton interactions.

Macrophage inhibitory cytokine-1/growth differentiation factor-15 as a predictor of colonic neoplasia.

BACKGROUND: Serum macrophage inhibitory cytokine-1 (MIC-1/GDF15) concentration has been associated with colonic adenomas and carcinoma. AIMS: To determine whether circulating MIC-1/GDF15 serum concentrations are higher in the presence of adenomas and whether the level decreases after excision. METHODS: Patients were recruited prospectively from a single centre and stratified into five groups: no polyps (NP); hyperplastic polyps (HP); sessile serrated ademona (SSA); adenomas (AP); and colorectal carcinoma (CRC). Blood samples were collected immediately before and 4 weeks after colonoscopy. MIC-1/GDF15 serum levels were quantified using ELISA. RESULTS: Participants (n=301) were stratified as: NP; n=116 (52%), HP; n=37 (12%), SSA; n=19 (7%), AP; n=68 (23%); and CRC; n=3 (1%). Patients were excluded from the study due to nondiagnostic pathology (n=9, 3%) and exclusion criteria (n=20, 6%). In the 272 remaining subjects (M=149; F=123), age (P=.005), history of colonic polyps (P=.003) and family history of colonic polyps (P=.002) were associated with presence of adenomas. Baseline median MIC-1/GDF15 serum levels increased significantly from NP 609 (460-797) pg/mL, HP 582 (466-852) pg/mL, SSA 561 (446-837) pg/mL to AP 723 (602-1122) pg/mL and CRC 1107 (897-1107) pg/mL; (P<.001). In the pre- and postpolypectomy paired adenoma samples median MIC-1/GDF15 reduced significantly from 722 (603-1164) pg/mL to 685 (561-944) pg/mL (P=.002). A ROC analysis for serum MIC-1/GDF15 to identify adenomatous polyps indicated an area under the curve of 0.71. CONCLUSIONS: Our data suggest that serum MIC-1/GDF15 has the diagnostic characteristics to increase the detection of colonic neoplasia and improve screening.

Are newborns receiving premedication before elective intubation?

AIMS: To determine the extent and type of premedication used for elective endotracheal intubation in neonatal intensive care units (NICUs). METHODS: A pretested questionnaire was distributed via e-mail to the program directors of the neonatology divisions with accredited fellowship programs in Neonatal-Perinatal Medicine in the United States. RESULTS: Of the 100 individuals contacted, 78 (78%) participated in the survey. Only 34 of the 78 respondents (43.6%) always use any premedication for elective intubation. Nineteen respondents (24.4%) reported to have a written policy regarding premedication. Morphine or fentanyl was used most commonly (57.1%), with a combination of opioids and midazolam or other benzodiazepines used less frequently. Fourteen respondents (25%) also use muscle relaxants with sedation for premedication, but only nine respondents combined paralysis with atropine and sedation. CONCLUSION: Most neonatology fellowship program directors do not report always using premedication for newborns before elective endotracheal intubation despite strong evidence of physiologic and practical benefits. Only a minority of the NICUs has written guidelines for sedation, which may preclude effective auditing of this practice. Educational interventions may be necessary to ensure changes in clinical practice.

Reduction of oxygen consumption, insensible water loss, and radiant heat demand with use of a plastic blanket for low-birth-weight infants under radiant warmers.

Eight very low-birth-weight premature infants (mean birth weight 1.11 +/- 0.05 [SEM]kg, mean gestation 30 +/- 1 weeks, and mean age 9 +/- 2 days) were studied under servocontrolled radiant warmers with and without a loosely fitted, transparent, and flexible Saran plastic blanket. Metabolic rate was significantly less in all infants when covered by the blanket (oxygen consumption was 7.99 +/- 1.13 mL/kg/min v 9.00 +/- 1.10 mL/kg/min uncovered, P less than .001). There were also significant reductions in insensible water loss (1.86 +/- 0.18 v 1.25 +/- 0.20 mL/kg/h, P less than .01) and in heat demand from the radiant warmer (14.3 +/- 1.3 v 9.9 +/- 1.4 mW/cm2, P less than .001) when infants were nursed under the blanket compared with the control condition, respectively. Covering the critically ill, very low-birth-weight infant nursed under a radiant heater with a thin, transparent layer of Saran is beneficial in reducing oxygen consumption, insensible water loss, and the need for exposure to high levels of radiant heat. Further investigation to confirm the benefits and possible complications of plastic blankets should be conducted before routine use can be recommended.

Partitioning of heat losses and gains in premature newborn infants under radiant warmers.

The partition of heat loss into convective and evaporative components, and heat gain into metabolic rate of production and radiant heat needed to maintain thermal equilibrium was determined in ten premature neonates (weight 1.39 +/- .08 [SEM] kg, gestation 31 +/- 1 weeks) who were nursed naked and supine on open radiant warmer beds. Warmer beds were servocontrolled to maintain each infant's abdominal skin temperature at three different levels: 35.5, 36.5, and 37.5 degrees C. The quantity of radiant heat delivered by the warmer in vivo was measured directly and compared with the heat need calculated from the partition. Convective heat loss comprised the major component of net heat loss and increased significantly with servocontrol temperature from 2.86 +/- .24 to 3.27 +/- .23 kcal/kg/h (P less than .01), and to 3.72 +/- .26 kcal/kg/h (P less than .001). Evaporative heat loss increased with servocontrol temperature from .96 +/- .13 to 1.41 +/- .33 kcal/kg/h, and to 1.35 +/- .32 kcal/kg/h, but this increase was not significant. Metabolic rate decreased from 2.08 +/- .17 to 1.90 +/- .14 kcal/kg/h, and to 1.78 +/- .16 kcal/kg/h with increased servocontrol temperature, but this decrease was not significant. Radiant heat needed to maintain infants at higher temperatures increased from 1.73 to 2.80 kcal/kg/h, and to 3.32 kcal/kg/h. The radiant heat delivered by the warmer to infants was directly proportional to the heat need calculated from the partition (r = .68, P less than .001).

Optimal thermal management for low birth weight infants nursed under high-powered radiant warmers.

Servocontrol of skin temperature for the critically ill premature neonate nursed on a radiant warmer bed has been assumed to be analogous to skin temperature control for infants nursed in convection-warmed incubators. There are significant differences between these two warming techniques, and no definitive data exist to aid the clinical specialist in governing radiant warmer control. Eighteen low birth weight premature infants less than 2 weeks of age were studied under powerful overhead radiant warmers to determine the optimal skin temperature for servocontrol of radiant heater output. Anterior abdominal wall temperature was servocontrolled at 35.5 degrees, 36.5 degrees, and 37.5 degrees C in a randomized fashion for three periods of 90 minutes each after thermal equilibrium was established. Oxygen consumption was measured during the entire 90-min sample period at each temperature by a computerized metabolic apparatus to determine the optimal thermal neutral control temperature defined as minimal oxygen consumption with normal body temperature. Skin, deep rectal, and environmental temperature measurements, as well as behavior assessments, were made concurrently. Oxygen consumption was significantly elevated at 35.5 degrees C (8.62 +/- 0.73 mL/kg/min, mean +/- SEM) compared with 36.5 degrees C (7.30 +/- 0.55 mL/kg/min). Changing servocontrol temperature to 37.5 degrees C produced no further significant decrease in oxygen consumption (7.41 +/- 0.70 mL/kg/min), and nine infants manifested supranormal deep rectal temperatures (greater than 37.5 degrees C). Optimal abdominal skin temperature control at 36.5 degrees C (slightly warmer than previously reported but less than 37.5 degrees C) is recommended for premature neonates nursed on radiant warmer beds.(ABSTRACT TRUNCATED AT 250 WORDS)

Semipermeable polyurethane membrane as an artificial skin for the premature neonate.

A thin and semipermeable polyurethane membrane adherently applied to premature neonates as an artificial skin was investigated as an atraumatic surface barrier sufficient to reduce transepidermal water loss without inhibiting natural infant skin development during the first few days of life. A sample group of 18 neonates (birth weight [mean +/- SEM] 1.39 +/- 0.12 kg, gestation [mean +/- SEM] 31 +/- 1 weeks) received two 3 X 3-cm polyurethane patches adherent over the chest and abdomen. Transepidermal water loss was measured before and after application and after membrane removal. During longitudinal study, seven infants were treated day 1 through day 4 of life and were evaluated for skin integrity 24 hours after patch removal on day 5. Polyurethane membranes produced an acute and significant reduction in transepidermal water loss for the 18 subjects: 21.1 +/- 2.0 g/m2/h before application v 10.5 +/- 1.4 g/m2/h with membranes in place (P less than .001). Immediately after patch removal, transepidermal loss returned to 22.8 +/- 3.0 g/m2/h. Throughout the first four days of life, daily measurements of water loss were significantly less: 53% to as much as 72% reduction from polyurethane-covered sites when compared with adjacent naked skin. After polyurethane membrane removal, skin development of transepidermal barrier function was comparable over both sites. Dressings did not lose adhesive or plastic properties during an extended time in either radiant warmer or incubator environments, electronic monitoring through membranes was not impeded, and adhesive injuries were not observed. An adherent, semipermeable polyurethane membrane may be effective as an atraumatic artificial barrier to prevent large transepidermal water loss and protect the skin of the premature neonate.

No lumbar puncture in the evaluation for early neonatal sepsis: will meningitis be missed?

OBJECTIVE: We performed this investigation to assess whether selective approaches to performing lumbar puncture (LP) in the early neonatal period will result in a missed or delayed diagnosis of bacterial meningitis. DESIGN: A retrospective review was conducted of the medical records of all neonates born in US Army hospitals from 1988 through 1992 who developed culture-positive meningitis during the first 72 hours of life. RESULTS: In total, 169,849 infants were born during the 5-year study period. The incidence of meningitis in the first 72 hours of life was 0.25 per 1000 live births. Forty-three infants had organisms isolated from their cerebrospinal fluid (30, group B streptococcus; 10, Escherichia coli; 1, Listeria monocytogenes; 1, Streptococcus pneumoniae; and 1, Citrobacter diversus). The median age of infants at evaluation was 12 hours, and the mean gestational age was 38.8 weeks (7 < 37 weeks), whereas mean birth weight was 3163 g (7 < 2500 g). If we had used currently advocated selective criteria as the basis for not performing an LP, the diagnosis of bacterial meningitis would have been missed or delayed in 16 of 43 infants (37%): 5 infants born prematurely with suspected respiratory distress syndrome, 3 asymptomatic infants born at term with positive blood cultures, and 8 infants born at term with no central nervous system symptoms and negative blood cultures. CONCLUSIONS: If LPs are omitted as part of the early neonatal sepsis evaluation, the diagnosis of bacterial meningitis occasionally will be delayed or missed completely.

Bilirubin photoisomerization in premature neonates under low- and high-dose phototherapy.

Photoisomerization of native bilirubin to more polar configurational isomers (Z,E-bilirubin) and structural isomers (lumirubin) was studied in 20 premature infants with physiologic jaundice to determine the effect of low-dose (6 microW/cm2/nm) v high-dose (12 microW/cm2/nm) phototherapy. Patients were assigned prospectively to receive either low- or high-dose treatment. Study groups were comparable with regard to birth weight, gestational age, and total bilirubin prior to the initiation of phototherapy. Treatment was administered with white light produced by a commercially available halogen-tungsten lamp. Dose was measured periodically during the study to ensure a uniform distribution of irradiance and constant exposure. Sera for photoisomers were obtained before initiation of treatment and at two, four, and eight hours. Photoisomers expressed as a percent of total bilirubin were determined using high-pressure liquid chromatography. Serum proportion of both configurational and structural isomers increased with the duration of phototherapy in both treatment groups. There was no significant difference between the percent of configurational isomers in low- and high-dose phototherapy groups. However, high-dose treatment produced a significantly higher proportion of the structural isomer lumirubin after four hours (0.7% low dose v 1.3% high dose, P less than .05). These data confirm that phototherapy results in both configurational and structural isomerization of bilirubin in vivo. Furthermore, the previously described "dose" effect of phototherapy may be attributed to the production of the structural isomer, lumirubin.

Distinguishing sepsis from blood culture contamination in young infants with blood cultures growing coagulase-negative staphylococci.

In the ideal situation, the evaluation for sepsis in the young infant should include collection of multiple blood cultures before the institution of antibiotics. Unfortunately, in some infants, it may not be possible to obtain more than a single blood culture at the time of initial evaluation. If this single culture ultimately grows coagulase-negative staphylococci and the infant has been treated with antimicrobial therapy in the interim, it is often difficult to determine whether the positive culture represents true infection or contamination. Our data suggest that peripheral blood cultures yielding high colony counts most likely represent infection. Furthermore, in this high-risk patient population, low colony-count growth should not be ignored as contamination, particularly if there are significant clinical findings or if the infant has a central catheter or hematologic abnormality. Future studies should examine these important issues.

Diagnosis-related criteria in the consideration of extracorporeal membrane oxygenation in neonates previously treated with high-frequency jet ventilation.

High-frequency jet ventilation (HFJV) is one of several high-frequency techniques that are particularly valuable for treating the neonate with lung disease refractory to conventional ventilation or with pulmonary air leak. Extracorporeal membrane oxygenation (ECMO) has also emerged as a valuable rescue therapy for neonates of more than 2000 g birth weight and 34 weeks' gestation with intractable respiratory failure. With the concurrent introduction of HFJV and ECMO, the authors sought to evaluate the role of HFJV prior to the institution of ECMO therapy. The data base for 2856 neonates receiving mechanical ventilation in one unit was used to identify 73 (of 298 total) neonates treated with HFJV, who were eligible by age and weight criteria for ECMO. Patients were grouped by diagnosis, and the oxygenation index (OI) was calculated during therapy. Outcome was evaluated for mortality, and the sensitivity of the OI for predicting mortality was calculated. Neonates who survived with HFJV alone presented with an OI of 0.30 +/- 0.03 (SEM), significantly less than nonsurvivors (0.42 +/- 0.04, P = .016). Survivors responded to HFJV with a rapid decrease in OI at 1 hour (0.19 +/- 0.02, P less than .001) and 6 hours (0.15 +/- 0.01, P less than .001). Nonsurvivors did not respond significantly at 1 hour (OI = 0.33 +/- 0.04, P = not significant [NS]) or at 6 hours (OI = 0.40 +/- 0.06, P = NS). By diagnosis, neonates with respiratory distress syndrome survived more often with HFJV (28/34, 82%) than neonates with meconium aspiration (10/26, 38%) or diaphragmatic hernia (3/9, 33%). Neonates with respiratory distress syndrome seldom presented with high OI values, but the majority of those who did survived (5/7 survived with initial OI greater than or equal to 0.40).(ABSTRACT TRUNCATED AT 250 WORDS)

Prognosis with preoperative pulmonary function and lung volume assessment in infants with congenital diaphragmatic hernia.

OBJECTIVES: To determine whether fatal pulmonary hypoplasia, as assessed by functional residual capacity (FRC), can be distinguished from other reversible causes of respiratory failure in infants with congenital diaphragmatic hernia (CDH). METHODS: In the present study, 25 term neonates having CDH without other anomalies (mean birth weight +/- SD, 3.25 +/- 0.50 kg) were enrolled prospectively into a protocol evaluating pulmonary function. Lung compliance (CL) and FRC were measured before diaphragmatic repair and compared with the highest oxygenation index (OI) and lowest PaCO2, also obtained preoperatively. Pulmonary function assessment was repeated after diaphragm repair on postoperative days 3 and 7. CL was determined by esophageal manometry and pneumotachography, and FRC was determined by helium dilution. RESULTS: Fifteen infants (60%) survived to hospital discharge. Eighteen (72%) required extracorporeal membrane oxygenation (ECMO) for support, and of these, 8 (44%) survived. PaCO2 was similar preoperatively in infants grouped as survivors without ECMO, survivors with ECMO, and nonsurvivors. In nonsurvivors (all of whom received ECMO), the preoperative OI was significantly higher (51 +/- 21), CL was less (0.11 +/- 0.04 mL/cm of water per kg), and FRC was smaller (4.5 +/- 1.0 mL/kg) than in the survivors who required ECMO (26 +/- 18, 0.18 +/- 0.08 mL/cm of water per kg, and 12 +/- 5 mL/kg, respectively), as well as in the survivors without ECMO, (6 +/- 2, 0.32 +/- 0.16 mL/cm of water per kg, and 15.8 +/- 4 mL/kg, respectively). The group surviving with ECMO had a higher OI than the infants surviving without ECMO. All nonsurviving infants had FRCs of less than 9.0 mL/kg preoperatively. In contrast, only 2 of the 15 survivors had preoperative FRCs less than 9 mL/kg. CONCLUSIONS: The results of this study suggest that preoperative assessment of FRC may predict fatal pulmonary hypoplasia in most infants with CDH.