The phase diagram of Ti-6Al-4V at high-pressures and high-temperatures.

We report results from a series of diamond-anvil-cell synchrotron x-ray diffraction and large-volume-press experiments, and calculations, to investigate the phase diagram of commercial polycrystalline high-strength Ti-6Al-4V alloy in pressure-temperature space. Up to ∼30 GPa and 886 K, Ti-6Al-4V is found to be stable in the hexagonal-close-packed, orαphase. The effect of temperature on the volume expansion and compressibility ofα-Ti-6Al-4V is modest. The martensiticα→ω(hexagonal) transition occurs at ∼30 GPa, with both phases coexisting until at ∼38-40 GPa the transition to theωphase is completed. Between 300 K and 844 K theα→ωtransition appears to be independent of temperature.ω-Ti-6Al-4V is stable to ∼91 GPa and 844 K, the highest combined pressure and temperature reached in these experiments. Pressure-volume-temperature equations-of-state for theαandωphases of Ti-6Al-4V are generated and found to be similar to pure Ti. A pronounced hysteresis is observed in theω-Ti-6Al-4V on decompression, with the hexagonal structure reverting back to theαphase at pressures below ∼9 GPa at room temperature, and at a higher pressure at elevated temperatures. Based on our data, we estimate the Ti-6Al-4Vα-ß-ωtriple point to occur at ∼900 K and 30 GPa, in good agreement with our calculations.

[Postcardiac arrest treatment guide]. / Praxisleitfaden für die Postreanimationsbehandlung.

BACKGROUND: Treatment after cardiac arrest has become more complex and interdisciplinary over the last few years. Thus, the clinically active intensive and emergency care physician not only has to carry out the immediate care and acute diagnostics, but also has to prognosticate the neurological outcome. AIM: The different, most important steps are presented by leading experts in the area, taking into account the interdisciplinarity and the currently valid guidelines. MATERIALS AND METHODS: Attention was paid to a concise, practice-oriented presentation. RESULTS AND DISCUSSION: The practical guide contains all important steps from the acute care to the neurological prognosis generation that are relevant for the clinically active intensive care physician.

Geometric localization in supported elastic struts.

Localized deformation patterns are a common motif in morphogenesis and are increasingly finding applications in materials science and engineering, in such instances as mechanical memories. Here, we describe the emergence of spatially localized deformations in a minimal mechanical system by exploring the impact of growth and shear on the conformation of a semi-flexible filament connected to a pliable shearable substrate. We combine numerical simulations of a discrete rod model with theoretical analysis of the differential equations recovered in the continuum limit to quantify (in the form of scaling laws) how geometry, mechanics and growth act together to give rise to such localized structures in this system. We find that spatially localized deformations along the filament emerge for intermediate shear modulus and increasing growth. Finally, we use experiments on a 3D-printed multi-material model system to demonstrate that external control of the amount of shear and growth may be used to regulate the spatial extent of the localized strain texture.

[Biomarkers after resuscitation : Relevance in daily clinical practice for prognosis estimation and definition of therapeutic goals]. / Biomarker nach Reanimation : Relevanz im klinischen Alltag für Prognoseeinschätzung und Therapiezieldefinition.

BACKGROUND: The assessment of the neurological prognosis after cardiac arrest should be made using a multimodal approach involving clinical, physical and laboratory findings. Here, biomarkers are of high importance. The reliable prognostication has far-reaching consequences for the patient on the further course of therapy and rehabilitation. OBJECTIVES: Which biomarkers help in prognosis estimation and therapy target definition and are currently used in daily clinical practice? MATERIALS AND METHODS: Presentation of the multimodal approach for prognosis generation in patients after resuscitation with hypoxic-ischemic encephalopathy with special consideration and discussion of various biomarkers. RESULTS AND CONCLUSION: Neuron-specific enolase (NSE) is the best-established predictive biomarker in patients with hypoxic-ischemic encephalopathy after cardiac arrest. In combination with other methods (clinical examination, physical testing) and considering possible interfering factors (hemolysis, tumor diseases), NSE is used after 48-72 h with a cutoff value of 90 ng/ml. Most other biomarkers have so far only been studied in smaller groups or individual studies and thus cannot currently be routinely used outside of studies.

Impact of acute kidney injury on neurological outcome and long-term survival after cardiac arrest - A 10 year observational follow up.

BACKGROUND: Acute kidney injury (AKI) may be associated with short- and long-term patient morbidity and mortality. Therefore, the impact of AKI after cardiac arrest on survival and neurological outcome was evaluated. METHODS: An observational single center study was conducted and consecutively included all out and in hospital cardiac arrest (OHCA/IHCA) patients treated with therapeutic temperature management between 2006 and 2013. Patient morbidity, mortality and neurological outcome according to the widely used Pittsburgh Cerebral Performance Category (CPC) were assessed. A good neurological outcome was defined as a CPC of 1-2 versus a poor neurological outcome with a CPC of 3-5. AKI was defined by using the KDIGO Guidelines 2012. RESULTS: 503 patients were observed in total. 29.4% (n = 148) developed AKI during their intensive care unit (ICU) stay. 70.6% (n = 355) did not experience AKI. The mean age at admission was 62 years, of those 72.8% were male and 77% experienced an out-of-hospital cardiac arrest (OHCA). AKI occurred with 41.2% more often in the group with poor neurological outcome compared to 17.1% in the group with good neurological outcome. The median survival for patients after cardiac arrest with AKI was 0.07 years compared to 6.5 years for patients without AKI. CONCLUSION: Our data suggest that AKI is a major risk factor for a poor neurological outcome and a higher mortality after cardiac arrest. Further important risk factors were age, time to ROSC and high NSE.

Improvement of lay rescuer chest compressions with a novel audiovisual feedback device : A randomized trial.

BACKGROUND: Bystander actions and skills determine among others the outcome of out-of-hospital cardiac arrest. However, the depth and rate of chest compressions (CC) are difficult to estimate for laypeople and poor CC quality may result. Our study aimed to evaluate the impact of a new feedback device on CC performance by laypeople. The percentage of CC with both correct rate and correct depth of all CC served as primary endpoint. METHODS: Forty-eight subjects with no medical background performed 2 min of CC on a manikin with and without a novel feedback device (TrueCPR™, Physio-Control, Redmond, Wash.). The device uses a novel, non-accelerometer-based technology. Participants were randomized into two groups. Group 1 performed a 2-min CC trial first with audiovisual feedback followed by a trial with no feedback information, while group 2 performed the task in reverse order. RESULTS: The absolute percentage of CC with correct rate and depth was significantly higher with the use of the device (59 ± 34% vs. 15 ± 21%, p < 0.0001). The longest interval without correct CC was significantly decreased (76.5 s vs. 27.5 s, p < 0.0001). CONCLUSION: The quality of CC carried out by laypeople is significantly improved with the use of a new feedback device. The device may be useful for cardiopulmonary resuscitation (CPR) by laypeople and for educational purposes.

Biophysical model of the role of actin remodeling on dendritic spine morphology.

Dendritic spines are small membranous structures that protrude from the neuronal dendrite. Each spine contains a synaptic contact site that may connect its parent dendrite to the axons of neighboring neurons. Dendritic spines are markedly distinct in shape and size, and certain types of stimulation prompt spines to evolve, in fairly predictable fashion, from thin nascent morphologies to the mushroom-like shapes associated with mature spines. It is well established that the remodeling of spines is strongly dependent upon the actin cytoskeleton inside the spine. A general framework that details the precise role of actin in directing the transitions between the various spine shapes is lacking. We address this issue, and present a quantitative, model-based scenario for spine plasticity validated using realistic and physiologically relevant parameters. Our model points to a crucial role for the actin cytoskeleton. In the early stages of spine formation, the interplay between the elastic properties of the spine membrane and the protrusive forces generated in the actin cytoskeleton propels the incipient spine. In the maturation stage, actin remodeling in the form of the combined dynamics of branched and bundled actin is required to form mature, mushroom-like spines. Importantly, our model shows that constricting the spine-neck aids in the stabilization of mature spines, thus pointing to a role in stabilization and maintenance for additional factors such as ring-like F-actin structures. Taken together, our model provides unique insights into the fundamental role of actin remodeling and polymerization forces during spine formation and maturation.

Critical behaviour in the nonlinear elastic response of hydrogels.

In this paper we study the elastic response of synthetic hydrogels to an applied shear stress. The hydrogels studied here have previously been shown to mimic the behaviour of biopolymer networks when they are sufficiently far above the gel point. We show that near the gel point they exhibit an elastic response that is consistent with the predicted critical behaviour of networks near or below the isostatic point of marginal stability. This point separates rigid and floppy states, distinguished by the presence or absence of finite linear elastic moduli. Recent theoretical work has also focused on the response of such networks to finite or large deformations, both near and below the isostatic point. Despite this interest, experimental evidence for the existence of criticality in such networks has been lacking. Using computer simulations, we identify critical signatures in the mechanical response of sub-isostatic networks as a function of applied shear stress. We also present experimental evidence consistent with these predictions. Furthermore, our results show the existence of two distinct critical regimes, one of which arises from the nonlinear stretch response of semi-flexible polymers.

Outcome prediction in patients after cardiac arrest: a simplified method for determination of gray-white matter ratio in cranial computed tomography.

PURPOSE: Out-of-hospital cardiac arrest is a frequent cause of death in Europe. Hypoxic ischemic encephalopathy (HIE) often develops in initial survivors, and the question of treatment limitation arises in severely affected patients. To establish a poor prognosis with a high level of certainty, the use of a combination of prognostic parameters such as neurological examination, somatosensory evoked potentials, and neuron-specific enolase is common practice. A few recent studies suggest that gray-white matter ratio (GWR) determined from cranial computed tomography (CT) scans is an additional reliable predictor of poor prognosis. The standard GWR determination method involves measurements of 16 different regions of interest (ROIs). We tested whether a simplified method to obtain GWR has equivalent reliability for poor outcome prediction. MATERIALS AND METHODS: We retrospectively analyzed 98 patients after cardiac arrest who had been treated with hypothermia. CT scans were obtained within the first 7 days after cardiac arrest. Neurological outcome was determined at intensive care unit discharge. Four different methods to obtain GWR were compared in a receiver-operating characteristic curve analysis with respect to their prognostic value for poor outcome prediction. RESULTS: The simplest method using only four ROIs (putamen and internal capsule bilaterally) had the same prognostic value compared with the standard method using 16 ROIs. The simplified GWR predicted poor outcome with a sensitivity of 44 % at 100 % specificity. CONCLUSION: Our results indicate that for poor outcome prediction in survivors of cardiac arrest, a simplified GWR determination is feasible and has the same reliability as the complex standard procedure.

Regional cerebral oxygen saturation after cardiac arrest in 60 patients--a prospective outcome study.

INTRODUCTION: Non-invasive near-infrared spectroscopy (NIRS) offers the possibility to determine regional cerebral oxygen saturation (rSO2) in patients with cardiac arrest. Limited data from recent studies indicate a potential for early prediction of neurological outcome. METHODS: Sixty cardiac arrest patients were prospectively enrolled, 22 in-hospital cardiac arrest (IHCA) and 38 out-of-hospital cardiac arrest (OHCA) patients respectively. NIRS of frontal brain was started after return of spontaneous circulation (ROSC) during admission to ICU and was continued until normothermia. Outcome was determined at ICU discharge by the Pittsburgh Cerebral Performance Category (CPC) and 6 months after cardiac arrest. RESULTS: A good outcome (CPC 1-2) was achieved in 23 (38%) patients, while 37 (62%) had a poor outcome (CPC 3-5). Patients with good outcome had significantly higher rSO2 levels (CPC 1-2: rSO2 68%; CPC 3-5: rSO2 58%; p<0.01). For good and poor outcome median rSO2 within the first 24h period was 66% and 59% respectively and for the following 16h period 68% and 59% (p<0.01). Outcome prediction by area of rSO2 below a critical threshold of rsO2=50% within the first 40h yielded 70% specificity and 86% sensitivity for poor outcome. CONCLUSION: On average, rSO2 within the first 40h after ROSC is significantly lower in patients with poor outcome, but rSO2 ranges largely overlap between outcome groups. Our data indicate limited potential for prediction of poor outcome by frontal brain rSO2 measurements.

Use of target temperature management after cardiac arrest in Germany--a nationwide survey including 951 intensive care units.

INTRODUCTION: Target temperature management (TTM) after cardiac arrest is recommended by international guidelines, which have been last updated in 2010. Here we investigate the status of implementation in a nationwide survey in Germany which took place in 2012. METHODS: We conducted a nationwide telephone survey including a total of 951 German intensive care units (ICUs). ICUs were identified by using the online registry for hospitals in Germany. A questionnaire was used for the interview about basic data of the intensive care unit and about details concerning use and implementation of TTM after cardiac arrest. RESULTS: The overall response rate was 91% (865/951). 86% (742/865) of ICUs used TTM after cardiac arrest and implementation peaked in 2010. 95% (702/736) of the ICUs using TTM perform treatment independently of the initial rhythm and 48% (355/738) apply TTM with the use of a feedback device for cooling and controlled re-warming. However, 22% (166/742) still use conventional methods like ice and cold infusion and only 61% (453/742) of the participants provided a written standard operating procedure (SOP). CONCLUSION: With a delay of several years, TTM after cardiac arrest is now implemented in the majority of German ICUs. The moderate proportion of ICUs using SOPs for TTM and feedback-controlled cooling devices indicates the need of further improvement in post cardiac arrest care.

Fluctuation-stabilized marginal networks and anomalous entropic elasticity.

We study the elastic properties of thermal networks of Hookean springs. In the purely mechanical limit, such systems are known to have a vanishing rigidity when their connectivity falls below a critical, isostatic value. In this work, we show that thermal networks exhibit a nonzero shear modulus G well below the isostatic point and that this modulus exhibits an anomalous, sublinear dependence on temperature T. At the isostatic point, G increases as the square root of T, while we find G∝Tα below the isostatic point, where α≃0.8. We show that this anomalous T dependence is entropic in origin.

Escherichia coli contamination of lettuce grown in soils amended with animal slurry.

A pilot study was conducted to assess the transfer of Escherichia coli from animal slurry fertilizer to lettuce, with E. coli serving as an indicator of fecal contamination and as an indicator for potential bacterial enteric pathogens. Animal slurry was applied as fertilizer to three Danish agricultural fields prior to the planting of lettuce seedlings. At harvest, leaves (25 g) of 10 lettuce heads were pooled into one sample unit (n = 147). Soil samples (100 g) were collected from one field before slurry application and four times during the growth period (n = 75). E. coli was enumerated in slurry, soil, and lettuce on 3M Petrifilm Select E. coli Count Plates containing 16 mg/liter streptomycin, 16 mg/liter ampicillin, or no antimicrobial agent. Selected E. coli isolates (n = 83) originating from the slurry, soil, and lettuce were genotyped by pulsed-field gel electrophoresis (PFGE) to determine the similarity of isolates. The slurry applied to the fields contained 3.0 to 4.5 log CFU/g E. coli. E. coli was found in 36 to 54% of the lettuce samples, streptomycin-resistant E. coli was found in 10.0 to 18.0% of the lettuce samples, and ampicillin-resistant E. coli in 0 to 2.0% of the lettuce samples (the detection limit was 1 log CFU/g). The concentration of E. coli exceeded 2 log CFU/g in 19.0% of the lettuce samples. No E. coli was detected in the soil before the slurry was applied, but after, E. coli was present until the last sampling day (harvest), when 10 of 15 soil samples contained E. coli. A relatively higher frequency of E. coli in lettuce compared with the soil samples at harvest suggests environmental sources of fecal contamination, e.g., wildlife. The higher frequency was supported by the finding of 21 different PFGE types among the E. coli isolates, with only a few common PFGE types between slurry, soil, and lettuce. The frequent finding of fecal-contaminated lettuce indicates that human pathogens such as Salmonella and Campylobacter can be present and represent food safety hazards.

Prognostication of neurologic outcome in cardiac arrest patients after mild therapeutic hypothermia: a meta-analysis of the current literature.

PURPOSE: To assess the sensitivity and false positive rate (FPR) of neurological examination and somatosensory evoked potentials (SSEPs) to predict poor outcome in adult patients treated with therapeutic hypothermia after cardiopulmonary resuscitation (CPR). METHODS: MEDLINE and EMBASE were searched for cohort studies describing the association of clinical neurological examination or SSEPs after return of spontaneous circulation with neurological outcome. Poor outcome was defined as severe disability, vegetative state and death. Sensitivity and FPR were determined. RESULTS: A total of 1,153 patients from ten studies were included. The FPR of a bilaterally absent cortical N20 response of the SSEP could be calculated from nine studies including 492 patients. The SSEP had an FPR of 0.007 (confidence interval, CI, 0.001-0.047) to predict poor outcome. The Glasgow coma score (GCS) motor response was assessed in 811 patients from nine studies. A GCS motor score of 1-2 at 72 h had a high FPR of 0.21 (CI 0.08-0.43). Corneal reflex and pupillary reactivity at 72 h after the arrest were available in 429 and 566 patients, respectively. Bilaterally absent corneal reflexes had an FPR of 0.02 (CI 0.002-0.13). Bilaterally absent pupillary reflexes had an FPR of 0.004 (CI 0.001-0.03). CONCLUSIONS: At 72 h after the arrest the motor response to painful stimuli and the corneal reflexes are not a reliable tool for the early prediction of poor outcome in patients treated with hypothermia. The reliability of the pupillary response to light and the SSEP is comparable to that in patients not treated with hypothermia.

Analytical expressions for the shape of axisymmetric membranes with multiple domains.

Based on the Canham-Helfrich free energy, we derive analytical expressions for the shapes of axisymmetric membranes consisting of multiple domains. We give explicit equations for both closed vesicles and almost cylindrical tubes. Using these expressions, we also find the shape of a tube attached to a spherical vesicle. The resulting shapes compare well to numerical data, and our expressions can be used to easily determine membrane parameters from experimentally obtained shapes.

Tympanic temperature during therapeutic hypothermia.

OBJECTIVE: Prehospital induction of therapeutic hypothermia after cardiac arrest may require temperature monitoring in the field. Tympanic temperature is non-invasive and frequently used in clinical practice. Nevertheless, it has not yet been evaluated in patients undergoing mild therapeutic hypothermia (MTH). Therefore, a prospective observational study was conducted comparing three different sites of temperature monitoring during therapeutic hypothermia. METHODS: Ten consecutive patients admitted to our medical intensive care unit after out-of-hospital cardiac arrest were included in this study. During MTH, tympanic temperature was measured using a digital thermometer. Simultaneously, oesophageal and bladder temperatures were recorded in a total of 558 single measurements. RESULTS: Compared with oesophageal temperature, bladder temperature had a bias of 0.019°C (limits of agreement ± 0.61°C (2SD)), and tympanic measurement had a bias of 0.021°C (± 0.80°C). Correlation analysis revealed a high relationship for tympanic versus oesophageal temperature (r = 0.95, p < 0.0001) and also for tympanic versus bladder temperature (r = 0.96, p < 0.0001). CONCLUSIONS: That tympanic temperature accurately indicates both oesophageal and bladder temperatures with a very small discrepancy in patients undergoing MTH after cardiac arrest is demonstrated in this study. Although our results were obtained in the hospital setting, these findings may be relevant for the prehospital application of therapeutic hypothermia as well. In this case, tympanic temperature may provide an easy and non-invasive method for temperature monitoring.