Two-channel pseudogap Kondo and Anderson models: Quantum phase transitions and non-Fermi liquids

We discuss the two-channel Kondo problem with a pseudogap density of states, \rho(\w)\propto|\w|^r, of the bath fermions. Combining both analytical and numerical renormalization group techniques, we characterize the impurity phases and quantum phase transitions of the relevant Kondo and Anderson models. The line of stable points, corresponding to the overscreened non-Fermi liquid behavior of the metallic $r=0$ case, is replaced by a stable particle-hole symmetric intermediate-coupling fixed point for 0. For r>\rmax, this non-Fermi liquid phase disappears, and instead a critical fixed point with an emergent spin--channel symmetry appears, controlling the quantum phase transition between two phases with stable spin and channel moments, respectively. We propose low-energy field theories to describe the quantum phase transitions, all being formulated in fermionic variables. We employ epsilon expansion techniques to calculate critical properties near the critical dimensions $r=0$ and $r=1$, the latter being potentially relevant for two-channel Kondo impurities in neutral graphene. We find the analytical results to be in excellent agreement with those obtained from applying Wilson's numerical renormalization group technique.Comment: Added reference

Prognostic factors in patients with acute mesenteric ischemia-novel tools for determining patient outcomes

BACKGROUND Acute mesenteric ischemia (AMI) is a devastating disease with poor prognosis. Due to the multitude of underlying factors, prediction of outcomes remains poor. We aimed to identify factors governing diagnosis and survival in AMI and develop novel prognostic tools. METHODS This monocentric retrospective study analyzed patients with suspected AMI undergoing imaging between January 2014 and December 2019. Subgroup analyses were performed for patients with confirmed AMI undergoing surgery. Nomograms were calculated based on multivariable logistic regression models. RESULTS Five hundred and thirty-nine patients underwent imaging for clinically suspected AMI, with 216 examinations showing radiological indication of AMI. Intestinal necrosis (IN) was confirmed in 125 undergoing surgery, 58 of which survived and 67 died (median 9 days after diagnosis, IQR 22). Increasing age, ASA score, pneumatosis intestinalis, and dilated bowel loops were significantly associated with presence of IN upon radiological suspicion. In contrast, decreased pH, elevated creatinine, radiological atherosclerosis, vascular occlusion (versus non-occlusive AMI), and colonic affection (compared to small bowel ischemia only) were associated with impaired survival in patients undergoing surgery. Based on the identified factors, we developed two nomograms to aid in prediction of IN upon radiological suspicion (C-Index = 0.726) and survival in patients undergoing surgery for IN (C-Index = 0.791). CONCLUSION As AMI remains a condition with high mortality, we identified factors predicting occurrence of IN with suspected AMI and survival when undergoing surgery for IN. We provide two new tools, which combine these parameters and might prove helpful in treatment of patients with AMI

Beobachtungsstudie ärztlicher und pflegerischer Aktivitäten in der Notaufnahme

Background!#!Comprehensive and systematic assessments of nurse and physician activities in the emergency department (ED) are lacking for German-speaking countries.!##!Objectives!#!Assessment of work activities of ED nurses and physicians with particular focus on frequencies of direct patient contact as well as rates of activity changes.!##!Material and methods!#!We employed standardized assessments of work activities using participant observations (90 min each) among nurses and physicians during their regular shifts. The setting was an interdisciplinary ED of a Southern German academic hospital. Observed activities were classified according to an established system and recorded with time stamps. Overall, 160 observation sessions were conducted (with an observation time of approximately 240 h; 99 among nurses, 61 among physicians).!##!Results!#!Physicians spent 30% of their working time in direct patient contact, nurses 44%. Concerning individual activities, the largest proportions of physicians' work time were allocated to documentation and writing (29.3%), communication with ED staff (16.9%) and patients (13.6%). Nurses were engaged in therapeutic and treatment activities (27.6%) and internal communication (17.9%) most of the time. Individual activities were highly fragmented: On average, we recorded 41.3 activities per hour with an average duration of 1.5 min. Nurses had significantly shorter activity durations than ED physicians (F[df = 1] = 4.5, p = 0.04). Activity-specific subanalyses revealed differences that could be attributed to professional roles in ED work.!##!Conclusion!#!Our results provide reliable and comprehensive insights into the distribution and duration of physician and nurse activities in clinical care in a German ED. Future work and design projects should focus particularly on effects of ED work time allocation on performance and work stress of ED staff as well as on safety and quality of ED patient care

A surface acoustic wave-driven micropump for particle uptake investigation under physiological flow conditions in very small volumes

Static conditions represent an important shortcoming of many in vitro experiments on the cellular uptake of nanoparticles. Here, we present a versatile microfluidic device based on acoustic streaming induced by surface acoustic waves (SAWs). The device offers a convenient method for introducing fluid motion in standard cell culture chambers and for mimicking capillary blood flow. We show that shear rates over the whole physiological range in sample volumes as small as 200 mu L can be achieved. A precise characterization method for the induced flow profile is presented and the influence of flow on the uptake of Pt-decorated CeO2 particles by endothelial cells (HMEC-1) is demonstrated. Under physiological flow conditions the particle uptake rates for this system are significantly lower than at low shear conditions. This underlines the vital importance of the fluidic environment for cellular uptake mechanisms

Total carbon column observing network (TCCON) activities at Izaña, Tenerife (28º N, 17º W) [Póster]

Póster presentado en: 37th Annual European Meeting on Atmospheric Studies by Optical Methods celebrado del 23 al 26 de agosto de 2010 en Valladolid

Intake of silica nanoparticles by giant lipid vesicles: influence of particle size and thermodynamic membrane state

The uptake of nanoparticles into cells often involves their engulfment by the plasma membrane and a fission of the latter. Understanding the physical mechanisms underlying these uptake processes may be achieved by the investigation of simple model systems that can be compared to theoretical models. Here, we present experiments on a massive uptake of silica nanoparticles by giant unilamellar lipid vesicles (GUVs). We find that this uptake process depends on the size of the particles as well as on the thermodynamic state of the lipid membrane. Our findings are discussed in the light of several theoretical models and indicate that these models have to be extended in order to capture the interaction between nanomaterials and biological membranes correctly

Left atrial diverticulum - An unexpected finding in routine transesophageal echocardiography

We report a 55-year-old male patient with lone paroxysmal atrial fibrillation who underwent routine transesophageal echocardiography (TOE) at our institution. In a mid-esophageal 125 degrees three-chamber angulation, a distinct thinning of the left atrial (LA) wall was observed, forming a 7 x 4 mm canal with only a small membrane separating the LA from the pericardial space. Cardiac magnetic resonance imaging diagnosed a small LA diverticulum. To the best of our knowledge, this is the first manuscript describing detection of a small LA diverticulum via TOE

Intake of silica nanoparticles by giant lipid vesicles: influence of particle size and thermodynamic membrane state

The uptake of nanoparticles into cells often involves their engulfment by the plasma membrane and a fission of the latter. Understanding the physical mechanisms underlying these uptake processes may be achieved by the investigation of simple model systems that can be compared to theoretical models. Here, we present experiments on a massive uptake of silica nanoparticles by giant unilamellar lipid vesicles (GUVs). We find that this uptake process depends on the size of the particles as well as on the thermodynamic state of the lipid membrane. Our findings are discussed in the light of several theoretical models and indicate that these models have to be extended in order to capture the interaction between nanomaterials and biological membranes correctly