Slowly breaking waves: the longevity of tidally induced spiral structure

Struck, Curtis,Dobbs, Clare L.,Hwang, Jeong‐,Sun Blackwell Publishing Ltd 2011 MONTHLY NOTICES- ROYAL ASTRONOMICAL SOCIETY Vol.414 No.3

<P><B>ABSTRACT</B></P><P>We have discovered long‐lived waves in two sets of numerical models of fast (marginally bound or unbound) flyby galaxy collisions, carried out independently with two different codes. In neither simulation set are the spirals the result of a collision‐induced bar formation. Although there is variation in the appearance of the waves with time, they do not disappear and reform recurrently, as seen in other cases described in the literature. We also present an analytic theory that can account for the wave structure, not as propagating transients, nor as a fixed pattern propagating through the disc. While these waves propagate through the disc, they are mantained by the coherent oscillations initiated by the impulsive disturbance. Specifically, the analytic theory suggests that they are caustic waves in ensembles of stars pursuing correlated epicyclic orbits after the disturbance. This theory is an extension of that developed by Struck and collaborators for colliding ring galaxies.</P><P>The models suggest that this type of wave may persist for a couple of Gyr, and galaxy interactions occur on comparable time‐scales, so waves produced by the mechanism may be well represented in observed spirals. In particular, this mechanism can account for the tightly wound, and presumably long‐lived, spirals seen in some nearby early‐type galaxies. These spirals are also likely to be common in groups and clusters, where fast encounters between galaxies occur relatively frequently. However, as the spirals become tightly wound, and evolve to modest amplitudes, they may be difficult to resolve unless they are nearby. None the less, the effect may be one of several processes that result from galaxy harassment, and via wave‐enhanced star formation, contributes to the Butcher–Oemler effect.</P>

Circulating Biologically Active Adrenomedullin Predicts Organ Failure and Mortality in Sepsis

김한아,허미나,Joachim Struck,Andreas Bergmann,Salvatore Di Somma 대한진단검사의학회 2019 Annals of Laboratory Medicine Vol.39 No.5

Background: Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. Biologically active adrenomedullin (bio-ADM) is an emerging biomarker for sepsis. We explored whether bio-ADM concentration could predict severity, organ failure, and 30-day mortality in septic patients. Methods: In 215 septic patients (109 patients with sepsis; 106 patients with septic shock), bio-ADM concentration was measured at diagnosis of sepsis, using sphingotest bio-ADM (Sphingotec GmbH, Hennigsdorf, Germany) and analyzed in terms of sepsis severity, vasopressor use, and 30-day mortality. The number of organ failures, sequential (sepsis-related) organ failure assessment (SOFA) score, and 30-day mortality were compared according to bio-ADM quartiles. Results: Bio-ADM concentration was significantly higher in patients with septic shock, vasopressor use, and non-survivors than in patients with solitary sepsis, no vasopressor use, and survivors, respectively (all P<0.0001). Bio-ADM quartiles were associated with the number of organ failures (P<0.0001), as well as SOFA cardiovascular, renal, coagulation, and liver subscores (all P<0.05). The 30-day mortality rate showed a stepwise increase in each bio-ADM quartile (all P<0.0001). Bio-ADM concentration and SOFA score equally predicted the 30-day mortality (area under the curve: 0.827 vs 0.830). Conclusions: Bio-ADM could serve as a useful and objective biomarker to predict severity, organ failure, and 30-day mortality in septic patients.

Models of Stephan’s Quintet: hydrodynamic constraints on the group’s evolution

Hwang, Jeong‐,Sun,Struck, Curtis,Renaud, Florent,Appleton, Philip N. Blackwell Publishing Ltd 2012 Monthly notices of the Royal Astronomical Society Vol.419 No.2

<P><B>ABSTRACT</B></P><P>We present smoothed particle hydrodynamic models of the interactions in the compact galaxy group, Stephan’s Quintet. This work is extension of the earlier collisionless <I>N</I>‐body simulations of Renaud et al. in which the large‐scale stellar morphology of the group was modelled with a series of galaxy–galaxy interactions in the simulations. Including thermohydrodynamic effects in this work, we further investigate the dynamical interaction history and evolution of the intergalactic gas of Stephan’s Quintet. The major features of the group, such as the extended tidal features and the group‐wide shock, enabled us to constrain the models reasonably well, while trying to reproduce multiple features of the system. We found that reconstructing the two long tails extending from NGC 7319 towards NGC 7320c one after the other in two separate encounters is very difficult and unlikely, because the second encounter usually destroys or distorts the already‐generated tidal structure. Our models suggest that the two long tails may be formed simultaneously from a single encounter between NGC 7319 and NGC 7320c, resulting in a thinner and denser inner tail than the outer one. The tails then also run parallel to each other as observed. The model results support the idea that the group‐wide shock detected in multiwavelength observations between NGC 7319 and NGC 7318b and also the starburst region north of NGC 7318b are triggered by the high‐speed collision between NGC 7318b and the intergalactic gas. Our models show that a gas bridge is formed by the high‐speed collision and clouds in the bridge continue to interact for some tens of millions of years after the impact. This produces many small shocks in that region, resulting in a much longer cooling time than that of a single impact shock.</P>

Proenkephalin Predicts Organ Failure, Renal Replacement Therapy, and Mortality in Patients With Sepsis

Hanah Kim,Mina Hur,Joachim Struck,Andreas Bergmann,Salvatore Di Somma,GREAT Network 대한진단검사의학회 2020 Annals of Laboratory Medicine Vol.40 No.6

Background: Kidney failure occurs frequently and is associated with high mortality during sepsis. Proenkephalin (PENK) is an emerging biomarker of kidney function. We explored whether PENK levels could predict severity, organ failure, and mortality in septic patients. Methods: We measured the PENK level in the plasma of 215 septic patients using the sphingotest penKid assay (Sphingotec GmbH, Hennigsdorf, Germany). This was analyzed in terms of sepsis severity, vasopressor use, 30-day mortality, sequential organ failure assessment (SOFA) renal subscore, the Chronic Kidney Disease Epidemiology Collaboration estimated glomerular filtration rate (CKD-EPI eGFR) categories, and renal replacement therapy (RRT) requirement. Results: The PENK levels were significantly higher in patients with septic shock, vasopressor use, and non-survivors than in patients with solitary sepsis, no vasopressor use, and survivors, respectively (P=0.02, P=0.007, P<0.001, respectively). The PENK levels were significantly associated with SOFA renal subscore and CKD-EPI eGFR categories (both P<0.001). The distribution of lower eGFR (<60 mL/min/1.73 m2), RRT requirement, SOFA renal subscore, and the number of organ failures differed significantly according to the PENK quartile (P for trend<0.001 or 0.017). The 30-day mortality rate also differed significantly according to the PENK quartile (P for trend<0.001). Conclusions: PENK could be an objective and reliable marker to predict severity, organ failure, and 30-day mortality in septic patients.

Proenkephalin, Neutrophil Gelatinase-Associated Lipocalin, and Estimated Glomerular Filtration Rates in Patients With Sepsis

김한아,허미나,이성호,Rossella Marino,Laura Magrini,Patrizia Cardelli,Joachim Struck,Andreas Bergmann,Oliver Hartmann,Salvatore Di Somma 대한진단검사의학회 2017 Annals of Laboratory Medicine Vol.37 No.5

Background: Proenkephalin (PENK) has been suggested as a novel biomarker for kidney function. We investigated the diagnostic and prognostic utility of plasma PENK in comparison with neutrophil gelatinase-associated lipocalin (NGAL) and estimated glomerular filtration rates (eGFR) in septic patients. Methods: A total of 167 septic patients were enrolled: 99 with sepsis, 37 with septic shock, and 31 with suspected sepsis. PENK and NGAL concentrations were measured and GFR was estimated by using the isotope dilution mass spectrometry traceable-Modification of Diet in Renal Disease (MDRD) Study and three Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations: CKD-EPICr, CDK-EPICysC, and CKD-EPICr-CysC. The PENK, NGAL, and eGFR results were compared according to sepsis severity, presence or absence of acute kidney injury (AKI), and clinical outcomes. Results: The PENK, NGAL, and eGFR results were significantly associated with sepsis severity and differed significantly between patients with and without AKI only in the sepsis group (all P<0.05). PENK was superior to NGAL in predicting AKI (P=0.022) and renal replacement therapy (RRT) (P=0.0085). Regardless of the variable GFR category by the different eGFR equations, PENK showed constant and significant associations with all eGFR equations. Unlike NGAL, PENK was not influenced by inflammation and predicted the 30-day mortality. Conclusions: PENK is a highly sensitive and objective biomarker of AKI and RRT and is useful for prognosis prediction in septic patients. With its diagnostic robustness and predictive power for survival, PENK constitutes a promising biomarker in critical care settings including sepsis.