A Study of Parton Energy Loss in Au+Au Collisions at RHIC using Transport Theory

Parton energy loss in Au+Au collisions at RHIC energies is studied by numerically solving the relativistic Boltzmann equation for the partons including $2 \leftrightarrow 2$ and $2 \to 2 + final state radiation$ collision processes. Final particle spectra are obtained using two hadronization models; the Lund string fragmentation and independent fragmentation models. Recent, preliminary $\pi^0$ transverse momentum distributions from central Au+Au collisions at RHIC are reproduced using gluon-gluon scattering cross sections of 5-12 mb, depending upon the hadronization model. Comparisons with the HIJING jet quenching algorithm are made.Comment: 6 pages, 6 figures, attached files are replaced (wrong files were uploaded in version 1

Acute type A dissection without intimal tear in arch: Proximal or extensive repair?

ObjectiveFor acute type A dissection without an intimal tear in the arch, the optimal surgical strategy is unknown. The present study was designed to clarify the issue by comparing the early and late outcomes of proximal (PR) and extensive repair (ER).MethodsFrom January 2002 to June 2010, 331 patients with acute type A dissection were treated surgically at our institute. Of these 331 patients, 197 were identified without an arch tear on the preoperative imaging examination and by intraoperative inspection. Of these 197 patients, 74 underwent proximal repair, including the aortic root, ascending aortic, or hemiarch repair, and 88 underwent extensive repair, including proximal repair, total arch replacement and a stented elephant trunk technique. The perioperative variables and late results were statistically analyzed.ResultsNo significant difference was found in the rates of early mortality and morbidity between the 2 groups, despite the shorter duration of circulatory arrest in the PR group. During long-term follow-up (mean, 55.7 ± 33.1 months; maximum, 129), the overall survival rate in the whole cohort was 100%, 90.8%, and 71.1% at 1, 5, and 8 years, respectively. No difference was found in survival between the 2 groups (P > .05). However, complete thrombosis of the false lumen in the proximal descending aorta was achieved in 100% of the ER group and 24.6% of the PR group (P < .001). For patients with a patent false lumen in the PR group, distal anastomosis leakage and unclosed small intimal tears were identified in 53.3% and 35.6% patients, respectively. The reintervention rate was also lower in the ER group than in the PR group (4.9% vs 15.9%, P < .05) during follow-up. Moreover, the reintervention rate for patients with Marfan syndrome was 9.5% in the ER group and 38.5% in the PR group (P < .05).ConclusionsFor patients with acute type A dissection without an intimal tear in the arch, extensive repair could promote the occlusion of distal false lumen and decrease the reintervention rate without increasing the operative risk

Genomic Insights into Speciation History and Local Adaptation of an Alpine Aspen in the Qinghai–Tibet Plateau and Adjacent Highlands

Natural selection serves as an important agent to drive and maintain interspecific divergence. Populus rotundifolia Griff. is an alpine aspen species that mainly occurs in the Qinghai–Tibet Plateau (QTP) and adjacent highlands, whereas its sister species, P. davidiana Dode, is distributed across southwest and central to northeast China in much lower altitude regions. In this study, we collected genome resequencing data of 53 P. rotundifolia and 42 P. davidiana individuals across their natural distribution regions. Our population genomic data suggest that the two species are well delimitated in the allopatric regions, but with hybrid zones in their adjacent region in the eastern QTP. Coalescent simulations suggest that P. rotundifolia diverged from P. davidiana in the middle Pleistocene with following continuous gene flow since divergence. In addition, we found numerous highly diverged genes with outlier signatures that are likely associated with high‐altitude adaptation of these alpine aspens. Our finding indicate that Quaternary climatic changes and natural selection have greatly contributed to the origin and distinction maintenance of P. rotundifolia in the QTP

Pharmacokinetics, tissue distribution, and metabolites of a polyvinylpyrrolidone-coated norcantharidin chitosan nanoparticle formulation in rats and mice, using LC-MS/MS

A novel formulation containing polyvinylpyrrolidone (PVP) K30-coated norcantharidin (NCTD) chitosan nanoparticles (PVP–NCTD–NPs) was prepared by ionic gelation between chitosan and sodium tripolyphosphate. The average particle size of the PVP–NCTD–NPs produced was 140.03 ± 6.23 nm; entrapment efficiency was 56.33% ± 1.41%; and drug-loading efficiency was 8.38% ± 0.56%. The surface morphology of NCTD nanoparticles (NPs) coated with PVP K30 was characterized using various analytical techniques, including X-ray diffraction and atomic force microscopy. NCTD and its metabolites were analyzed using a sensitive and specific liquid chromatography-tandem mass spectrometry method with samples from mice and rats. The results indicated the importance of the PVP coating in controlling the shape and improving the entrapment efficiency of the NPs. Pharmacokinetic profiles of the NCTD group and PVP–NCTD–NP group, after oral and intravenous administration in rats, revealed that relative bioavailabilities were 173.3% and 325.5%, respectively. The elimination half-life increased, and there was an obvious decrease in clearance. The tissue distribution of NCTD in mice after the intravenous administration of both formulations was investigated. The drug was not quantifiable at 6 hours in all tissues except for the liver and kidneys. The distribution of the drug in the liver and bile was notably improved in the PVP–NCTD–NP group. The metabolites and excretion properties of NCTD were investigated by analyzing rat feces and urine samples, collected after oral administration. A prototype drug and two metabolites were found in the feces, and seven metabolites in the urine. The primary elimination route of NCTD was via the urine. The quantity of the parent drug eliminated in the feces of the PVP–NCTD–NP group, was 32 times greater than that of the NCTD group, indicating that the NPs dramatically increased the reduction quantity from liver to bile. We conclude that PVP–NCTD–NPs are an adequate formulation for enhancing the absorption of NCTD, and significantly improving therapeutic effects targeting the hepatic system. Decarboxylation and hydroxylation were the dominant metabolic pathways for NCTD. Metabolites were mainly excreted into rat kidney and finally into urine