Observation of D0 meson nuclear modifications in Au+Au collisions at sqrt[s(NN)] = 200 GeV

We report the first measurement of charmed-hadron (D(0)) production via the hadronic decay channel (D(0) → K(-) + π(+)) in Au+Au collisions at sqrt[s(NN)] = 200 GeV with the STAR experiment. The charm production cross section per nucleon-nucleon collision at midrapidity scales with the number of binary collisions, N(bin), from p+p to central Au+Au collisions. The D(0) meson yields in central Au + Au collisions are strongly suppressed compared to those in p+p scaled by N(bin), for transverse momenta p(T) > 3 GeV/c, demonstrating significant energy loss of charm quarks in the hot and dense medium. An enhancement at intermediate p(T) is also observed. Model calculations including strong charm-medium interactions and coalescence hadronization describe our measurements.

Measurement of longitudinal spin asymmetries for weak boson production in polarized proton-proton collisions at RHIC

We report measurements of single- and double-spin asymmetries for W^{±} and Z/γ^{*} boson production in longitudinally polarized p+p collisions at sqrt[s]=510  GeV by the STAR experiment at RHIC. The asymmetries for W^{±} were measured as a function of the decay lepton pseudorapidity, which provides a theoretically clean probe of the proton's polarized quark distributions at the scale of the W mass. The results are compared to theoretical predictions, constrained by polarized deep inelastic scattering measurements, and show a preference for a sizable, positive up antiquark polarization in the range 0.05<x<0.2.

Beam-energy dependence of charge separation along the magnetic field in Au+Au collisions at RHIC

Local parity-odd domains are theorized to form inside a quark-gluon plasma which has been produced in high-energy heavy-ion collisions. The local parity-odd domains manifest themselves as charge separation along the magnetic field axis via the chiral magnetic effect. The experimental observation of charge separation has previously been reported for heavy-ion collisions at the top RHIC energies. In this Letter, we present the results of the beam-energy dependence of the charge correlations in Au+Au collisions at midrapidity for center-of-mass energies of 7.7, 11.5, 19.6, 27, 39, and 62.4 GeV from the STAR experiment. After background subtraction, the signal gradually reduces with decreased beam energy and tends to vanish by 7.7 GeV. This implies the dominance of hadronic interactions over partonic ones at lower collision energies.

Beam-energy dependence of the directed flow of protons, antiprotons, and pions in Au+Au collisions

Rapidity-odd directed flow (v1) measurements for charged pions, protons, and antiprotons near midrapidity (y=0) are reported in sNN=7.7, 11.5, 19.6, 27, 39, 62.4, and 200 GeV Au+Au collisions as recorded by the STAR detector at the Relativistic Heavy Ion Collider. At intermediate impact parameters, the proton and net-proton slope parameter dv1/dy|y=0 shows a minimum between 11.5 and 19.6 GeV. In addition, the net-proton dv1/dy|y=0 changes sign twice between 7.7 and 39 GeV. The proton and net-proton results qualitatively resemble predictions of a hydrodynamic model with a first-order phase transition from hadronic matter to deconfined matter, and differ from hadronic transport calculations.

Jet-hadron correlations in √[s(NN)]=200 GeV p+p and central Au+Au collisions

Azimuthal angular correlations of charged hadrons with respect to the axis of a reconstructed (trigger) jet in Au+Au and p+p collisions at √[s(NN)]=200  GeV in STAR are presented. The trigger jet population in Au+Au collisions is biased toward jets that have not interacted with the medium, allowing easier matching of jet energies between Au+Au and p+p collisions while enhancing medium effects on the recoil jet. The associated hadron yield of the recoil jet is significantly suppressed at high transverse momentum (pTassoc) and enhanced at low pTassoc in 0%-20% central Au+Au collisions compared to p+p collisions, which is indicative of medium-induced parton energy loss in ultrarelativistic heavy-ion collisions.

Effect of intermittent hypoxia on rat INS-1 cells and the protective effect of melatonin

OBJECTIVES

This study aimed to observe the influence of intermittent hypoxia on rat INS-1 cells and the protective effect of melatonin (MT).

MATERIALS AND METHODS

Intermittent hypoxia condition was induced in rat INS-1 cells. The supernatants were used to detect oxidative stress indicators, and the cells were used to detect JNK1 mRNA and JNK1/2 protein. After different dose-dependent interventions of MT, the cells were harvested to observe corresponding oxidative stress indicators and JNK1/2 protein change.

RESULTS

With prolonged exposure time, malondialdehyde (MDA) increased in cultured supernatants whereas superoxide dismutase (SOD) activity decreased. Cells with intermittent hypoxia showed significantly increased JNK1 mRNA expression, whereas phosphorylated JNK1 was highly expressed on the third day. With increased MT dose, MDA in cultured supernatants decreased whereas SOD activity increased. In the group dosed with 100 µM MT, phosphorylated JNK1 protein expression significantly decreased.

CONCLUSIONS

Intermittent hypoxia can cause oxidative damage to INS-1 cells possibly by increasing the JNK1 transcription level and protein activation. A high dose of MT (100 µM) can protect INS-1 cells from oxidative damage induced by intermittent hypoxia.

Establishment of an animal model of spontaneous cervical lymph node metastasis of laryngeal squamous cell carcinoma and obtaining laryngocarcinoma cells with high metastatic potential

To establish an animal model of spontaneous cervical lymph node metastasis of laryngeal squamous cell carcinoma and obtain laryngocarcinoma cells with high metastatic potential, laryngeal squamous cell carcinoma cell line HEP-2 in logarithmic phase were inoculated under the lingual margin mucosa of nude mice. HEP-2 cells metastasized to the cervical lymph nodes were isolated, cultured, and re-inoculated under the lingual margin mucosa of nude mice twice. The tumor formation in the tongue and in the cervical lymph nodes was confirmed by pathological examination. Carcinoma cells' ability of invasion and migration was detected by transwell assay. Human specific Alu sequences were detected by PCR, which indicated that the tumor cells originated from human laryngeal squamous cell carcinoma cell line HEP-2. Finally, an animal model of spontaneous lymph node metastasis of laryngeal squamous cell carcinoma was successfully established. Laryngeal squamous cell carcinoma cells with high metastatic potential to lymph nodes were obtained through repeated inoculations. .

Prediction for relapse and prognosis of newly diagnosed epilepsy

OBJECTIVE

The objective of this study was to investigate the timing of therapy initiation and other clinical factors as potential predictors for relapse and prognosis of epilepsy, based on hospital-based prospective observational data in China.

METHODS

One hundred and seventy-one newly diagnosed patients with one or more seizures were recruited and followed for at least 2 years. Kaplan-Meier survival analysis was used for calculating recurrence and remission rates. Univariate and multivariate analyses for risk factors were performed using Cox proportional hazards model.

RESULTS

Among the 171 patients analyzed, more patients had partial (54.4%) than generalized seizures (45.6%). The range of patients' age was 6-70 years, but 70% were under 16 years of age. Multiple seizure types (HR = 2.01; 95% CI, 1.31-3.10), epileptiform electroencephalogram (EEG) abnormality (HR = 1.95; 95% CI, 1.09-3.49), and >1 seizure monthly before treatment (HR = 2.74; 95% CI, 1.69-4.51) were predictors of seizure recurrence. The best negative predictors of remission were as follows: relapse (HR = 0.13; 95% CI, 0.07-0.23) and epileptiform EEG within 1 year of treatment (HR = 0.61; 95% CI, 0.39-0.97). Delayed treatment after three or more seizures did not significantly increase the risk of recurrence (P = 0.70) or remission (P = 0.31) compared with early treatment after one or two seizures.

CONCLUSIONS

Multiple seizure types, epileptiform EEG abnormality, and >1 seizure monthly before treatment predict seizure recurrence. Relapse and epileptiform EEG within 1 year of treatment predict adverse seizure outcome. Early treatment does not affect relapse or prognosis.

Frequency stability of a dual-mode whispering gallery mode optical reference cavity

We report an investigation of laser frequency stabilization using a whispering gallery mode resonator that is temperature stabilized by a dual-mode technique. This dual-mode technique has yielded mode volume temperature instabilities at the nK level, suggesting that high frequency stability may also be reached. Here, we experimentally and theoretically investigate the dynamics of such a system and the important factors affecting the achievable frequency stability. We calculate that the dual-mode technique can reduce the effective fractional temperature coefficient of the reference system to 3.6×10⁻⁸ K⁻¹ within the temperature feedback bandwidth. We demonstrate a 1560 nm laser stabilized to 1.3×10⁻¹² at 1 s and 1.1×10⁻¹⁰ at 1000 s, corresponding to a long-term drift of 21 kHz/hr.