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.

The role of 3d electrons in the appearance of ferromagnetism in the antiferromagnetic Ru2MnGe Heusler compound: a magnetic Compton scattering study

The antiferromagnetism in Ru(2)MnGe can be suppressed by the substitution of V by Mn and ferromagnetism appears. Synchrotron-based magnetic Compton scattering experiments are used in order to investigates the role of 3d electrons in the indirect/direct exchange interactions for the appearance of ferromagnetism. A small spin moment for the itinerant electron part on the magnetic Compton profile indicates that the metallic ferromagnet Ru(2)Mn(0.5)V(0.5)Ge has a weak indirect exchange interaction between the d-like and sp-like (itinerant) electrons. This suggests that the appearance of ferromagnetism is caused by the enhancement of the direct exchange interactions between d-d electrons in the Ru(2)MnGe Heusler compound. These findings indicate that the indirect exchange interaction between itinerant electrons and localized electrons is a significant key point for the appearance of ferromagnetism in this system.

Prognostic significance of lymphovascular invasion for patients with stage I non-small cell lung cancer

AIMS

This study retrospectively investigated the clinical significance of lymphovascular invasion (LVI) following a complete resection for stage I non-small cell lung cancer (NSCLC).

METHODS

A total of 226 patients who underwent a complete resection for pathological stage I NSCLC were examined.

RESULTS

Lymphatic invasion was pathologically diagnosed as ly0 in 156 patients, ly1 in 65, and ly2 in 5 patients. The pathological vascular invasion was diagnosed as v0 in 178 patients, v1 in 35, v2 in 10, and v3 in 3 patients. The 5-year survival rate after surgery of the patients with and without lymphatic invasion was 76.8 and 90.6%, respectively. There was a significantly more unfavorable prognosis in patients with lymphatic invasion (p = 0.042). The 5-year survival rate of the patients with vascular invasion was also significantly more unfavorable (67.8%) than that of patients without vascular invasion (90.4%; p = 0.004). LVI was found to significantly correlate with tumor size and the presence of pleural invasion.

CONCLUSION

The LVI of NSCLC is a significant prognostic factor in patients with stage I tumors. In future clinical trials, it is necessary to evaluate the efficacy of adjuvant therapy for the selection of patients according to this criterion.

A Study of Surgically Resected Peripheral Non-Small Cell Lung Cancer with a Tumor Diameter of 1.0 CM or Less

Background and Aims:

The widespread use of high resolution computed tomography has increased the number of small peripheral lung cancers. This study reviewed the clinicopathological features of the patients with non-small cell lung cancer (NSCLC) with a tumor diameter of 1 cm or less, in order to explore the adequate management of such small sized lung cancers.

Material and Methods:

This study was a retrospective analysis of consecutive 58 patients (5.3% out of 1095 patients) who underwent a complete resection for a peripheral NSCLC with a diameter of 1.0 cm or less. The clinical features and outcomes were compared with 203 patients with NSCLC with a diameter between 1.1 and 2.0 cm.

Results:

The mean age was 64.5 years and there were 26 males and 32 females. Clinical stage was IA in 57 (98%) and IIIA in 1. Lobectomy was performed in 39 patients, segmentectomy in nine, and nonanatomic wedge resection in ten. Two patients, who underwent systemic lymph node dissection, had mediastinal lymph node metastasis and were diagnosed as pathological stage IIIA; however they did not relapse after surgery. One patient with pathological stage IA papillary adenocarcinoma died due to brain metastases. The five-year overall survival rate and disease free survival rate was 95.0% and 95.3%, respectively. Patients with NSCLC of 1.0 cm or less showed significantly better survival than those with tumors measuring 1.1–2.0 cm in size (p = 0.048).

Discussion:

The indications for avoiding systemic lymph node dissection for operable NSCLC should not be based on the size of the tumor. A small-sized lung cancer might be surgically treated before the tumor enlarges to more than 1.0 cm in size.

Radiation pneumonitis in patients with lung and mediastinal tumours: a retrospective study of risk factors focused on pulmonary emphysema

OBJECTIVES

To evaluate the impact of pulmonary emphysema (PE) on the incidence and severity of radiation pneumonitis (RP) in patients with lung and mediastinal tumours.

METHODS

92 patients were enrolled. Involved-field radiation therapy (non-small cell carcinoma or mediastinal tumours in 69 patients; median 70 Gy) and accelerated hyperfractionation (limited disease small cell carcinoma in 23 patients; median 45 Gy) were performed. Common Terminology Criteria for Adverse Events v.3.0 was used to evaluate RP and the relationship with the percentage of pulmonary volume irradiated to >20 Gy (V20) and PE. PE was diagnosed by the presence of low-attenuation areas (LAAs) on CT scans and was classified into Grades 0-4 according to the extent of the LAAs.

RESULTS

The median follow-up time was 16 months. The 6-month cumulative incidence of RP at Grade 3 or greater was 7.7% and 34.1% in patients with a V20 of <25% and ≥25%, respectively (p=0.017). In patients with PE Grades 0, 1, 2 and 3 or greater, the incidence of RP was 16.5%, 9.1%, 8.6% and 54.0%, respectively. As the PE Grade increased, the incidence of RP also increased significantly.

CONCLUSION

The incidence and severity of RP are significantly higher in patients with a high V20 value as well as in those with severe PE.

Outcomes of chemoradiotherapy with a high irradiation dose using a 3D radiation treatment planning system for esophageal cancer

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Background: The standard irradiation dose of chemoradiotherapy (CRT) for esophageal cancer is 50.4 Gy, however, the trials in which this standard dose was originated were based on 2D radiation treatment planning. In this study we assessed the survival and toxicities of CRT with a dose of 60-66 Gy using a 3D radiation treatment planning system (3DRTPS) for esophageal cancer.

Methods: One hundred and two eligible patients with esophageal cancer treated by definitive CRT between 2000 and 2006 were assessed. Median age was 67 years old. There were stage I in 22 patients, stage II-III (without T4) in 27 and T4/M1Lymph legions in 53. There were 100 patients with squamous cell carcinoma histology and 2 with small cell carcinoma. Main tumor sites were cervical/upper/middle/lower thoracic in 15/19/43/25 patients. Treatment planning of irradiation was performed using a CT based 3DRTPS. Total irradiation dose of our protocol was 60-66 Gy. Accomplishment rate of planned irradiation was 93%. All patients received chemotherapy concurrently with radiotherapy. Fluorouracil based chemotherapy was performed in 96 patients (94%).

Results: The data was updated in August 2010. The median follow-up was 67 months. Cause-specific survival rates at 5 years for stage I, II-III (without T4) and T4/M1lymph were 100%, 49% and 17%, respectively and overall survival rates were 66%, 35% and 13%, respectively. Complete response (CR) rates were 100%, 79% and 35%, respectively and failure rates of CR cases were 5%, 43% and 42%, respectively. Late adverse effects (≥ grade 3) were observed in 11 patients (10%); pneumonitis in 4 (4%), pleural effusion in 4 (4%) and pericardial effusion in 5 (5%). Treatment related deaths were observed in 2 cases (pneumonitis developed during treatment in 1 and debility due to treatment in 1).

Conclusions: Toxicities of CRT with a high irradiation dose using 3DRTPS for esophageal cancer were acceptable and survival was promising. Dose intensification study of 50.4 Gy versus ≥ 60 Gy in CRT using a 3D-conformal radiation therapy technique for esophageal cancer should be considered.

No significant financial relationships to disclose.

Synthesis of cold antihydrogen in a cusp trap

We report here the first successful synthesis of cold antihydrogen atoms employing a cusp trap, which consists of a superconducting anti-Helmholtz coil and a stack of multiple ring electrodes. This success opens a new path to make a stringent test of the CPT symmetry via high precision microwave spectroscopy of ground-state hyperfine transitions of antihydrogen atoms.

Variation of the Ru moment in the Ca(0.3)Sr(0.7)Ru(1-x)Mn(x)O3 system

The variation of the magnetic moment on Ru and Mn atoms in the Ca(0.3)Sr(0.7)Ru(1-x)Mn(x)O(3) system was investigated by the magnetic Compton scattering technique using synchrotron radiation. The Ca(0.3)Sr(0.7)Ru(1-x)Mn(x)O(3) system has ferrimagnetism with an antiferromagnetic coupling between Ru and Mn, and the dominant magnetic component changes from ferromagnetic Ru to ferromagnetic Mn at x ∼0.25 as the Mn substitution proceeds. The mechanism for the change in the magnetism of Ca(0.3)Sr(0.7)Ru(1-x)Mn(x)O(3) is discussed.

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.