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Charmonium production and absorption in heavy ion collisions is studied with the Ultrarelativisitic Quantum Molecular Dynamics model. We compare the scenario of universal and time independent color-octet dissociation cross sections with one of distinct color-singlet J/psi, psi 2 and CHIc states, evolving from small, color transparent configurations to their asymptotic sizes. The measured J/psi production cross sections in pA and AB collisions at SPS energies are consistent with both purely hadronic scenarios. The predicted rapidity dependence of J/psi suppression can be used to discriminate between the two experimentally. The importance of interactions with secondary hadrons and the applicability of thermal reaction kinetics to J/psi absorption are in- vestigated. We discuss the e ect of nuclear stopping and the role of leading hadrons. The dependence of the 2/J/psi ratio on the model assumptions and the possible influence of refeeding processes is also studied.
Under certain conditions, secondary organic aerosol (SOA) particles can exist in the atmosphere in an amorphous solid or semi-solid state. To determine their relevance to processes such as ice nucleation or chemistry occurring within particles requires knowledge of the temperature and relative humidity (RH) range for SOA to exist in these states. In the Cosmics Leaving Outdoor Droplets (CLOUD) experiment at The European Organisation for Nuclear Research (CERN), we deployed a new in situ optical method to detect the viscous state of α-pinene SOA particles and measured their transition from the amorphous highly viscous state to states of lower viscosity. The method is based on the depolarising properties of laboratory-produced non-spherical SOA particles and their transformation to non-depolarising spherical particles at relative humidities near the deliquescence point. We found that particles formed and grown in the chamber developed an asymmetric shape through coagulation. A transition to a spherical shape was observed as the RH was increased to between 35 % at −10 °C and 80 % at −38 °C, confirming previous calculations of the viscosity-transition conditions. Consequently, α-pinene SOA particles exist in a viscous state over a wide range of ambient conditions, including the cirrus region of the free troposphere. This has implications for the physical, chemical, and ice-nucleation properties of SOA and SOA-coated particles in the atmosphere.
Under certain conditions, secondary organic aerosol (SOA) particles can exist in the atmosphere in an amorphous solid or semi-solid state. To determine their relevance to processes such as ice nucleation or chemistry occurring within particles requires knowledge of the temperature and relative humidity (RH) range for SOA to exist in these states. In the CLOUD experiment at CERN, we deployed a new in-situ optical method to detect the viscosity of α-pinene SOA particles and measured their transition from the amorphous viscous to liquid state. The method is based on the depolarising properties of laboratory-produced non-spherical SOA particles and their transformation to non-depolarising spherical liquid particles during deliquescence. We found that particles formed and grown in the chamber developed an asymmetric shape through coagulation. A transition to spherical shape was observed as the RH was increased to between 35 % at −10 ◦C and 80 % at −38 ◦C, confirming previous calculations of the viscosity transition conditions. Consequently, α-pinene SOA particles exist in a viscous state over a wide range of ambient conditions, including the cirrus region of the free troposphere. This has implications for the physical, chemical and ice-nucleation properties of SOA and SOA-coated particles in the atmosphere.
Background: Hypothermia has been discussed as playing a role in improving the early phase of systemic inflammation. However, information on the impact of hypothermia on the local inflammatory response is sparse. We therefore investigated the kinetics of local and systemic inflammation in the late posttraumatic phase after induction of hypothermia in an established porcine long-term model of combined trauma.
Materials & Methods: Male pigs (35 ± 5kg) were mechanically ventilated and monitored over the study period of 48 h. Combined trauma included tibia fracture, lung contusion, liver laceration and pressure-controlled hemorrhagic shock (MAP < 30 ± 5 mmHg for 90 min). After resuscitation, hypothermia (33°C) was induced for a period of 12 h (HT-T group) with subsequent re-warming over a period of 10 h. The NT-T group was kept normothermic. Systemic and local (fracture hematoma) cytokine levels (IL-6, -8, -10) and alarmins (HMGB1, HSP70) were measured via ELISA.
Results: Severe signs of shock as well as systemic and local increases of pro-inflammatory mediators were observed in both trauma groups. In general the local increase of pro- and anti-inflammatory mediator levels was significantly higher and prolonged compared to systemic concentrations. Induction of hypothermia resulted in a significantly prolonged elevation of both systemic and local HMGB1 levels at 48 h compared to the NT-T group. Correspondingly, local IL-6 levels demonstrated a significantly prolonged increase in the HT-T group at 48 h.
Conclusion: A prolonged inflammatory response might reduce the well-described protective effects on organ and immune function observed in the early phase after hypothermia induction. Furthermore, local immune response also seems to be affected. Future studies should aim to investigate the use of therapeutic hypothermia at different degrees and duration of application.