Najbolji izbor – kako izabrati odgovarajući uređaj?

An increasing number of patients suffering from end-stage heart failure require VAD implantation as either a bridge-to-transplantation or destination therapy. The choice of the right device depends upon the medical urgency; the need of uni- or biventricular support; the duration of support expected; and the institutional availability. Patients with multi-organ failure and unclear neurological situation can be supported with rotary pumps/ECMO first, and in case of recovery, a paracorporeal system can be connected to the previously implanted cannulas. In stable patients qualifying for left ventricular support, an intracorporeal system of the second generation can be implanted, allowing freedom of movement for 6-8 hours before recharging becomes necessary, and support intervals exceeding 1 year. Restrictions are given by the need of high-dose anticoagulation and a certain complication rate, especially in the first 3 months (bleeding, thromboembolism, infection, mechanical failure). The survival rate after the primary LVAD implantation is 74 % after 12 months and 55 % after 24 months; this is significantly better than the survival rate after RVAD, BVAD or TAH.Sve veći broj pacijenata u terminalnoj fazi zatajivanja srca zahtijevaju ugradnju mehaničke potpore srcu i cirkulaciji, kao premoštenje do transplantacije srca ili kao destinacijska terapija. Odabir odgovarajućeg uređaja ovisi o kliničkom stanju pacijenta, potrebi za jednostrukom ili dvostrukom ventrikularnom potporom, očekivanom trajanju ugrađene potpore i mogućnostima institucije. Pacijentima s multi organskim zatajenjem i nejasnim neurološkim smetnjama može se prvo ugraditi rotacijska pumpa/ECMO, te u slučaju oporavka., parakorporalni uređaj može biti povezan s ranije implantiranim kanilama. Kod stabilnih pacijenata, predodređenih za ugradnju potpore lijevom ventriklu, moguće je ugraditi intrakorporalni uređaj druge generacije, koji dozvoljava slobodno kretanje 6-8 sati do punjenja baterija i podupire intervale preko jedne godine. Ograničenja nastaju zbog potrebe za visokim dozama antikoagulacijske terapije i pojave određenih komplikacija, posebno u prva tri mjeseca nakon implantacije (krvarenje, tromboembolija, infekcija, mehaničke nepravilnosti). Stopa preživljenja 12 mjeseci nakon ugradnje LVAD-a je 74% i 55% nakon 24 mjeseca što je značajno bolje nego preživljenje nakon ugradnje RVAD, BVAD or TAH

Combining EGM2008 and SRTM/DTM2006.0 residual terrain model data to improve quasigeoid computations in mountainous areas devoid of gravity data

A global geopotential model, like EGM2008, is not capable of representing the high-frequency components of Earth?s gravity field. This is known as the omission error. In mountainous terrain, omission errors in EGM2008, even when expanded to degree 2,190, may reach amplitudes of10cm and more for height anomalies. The present paper proposes the utilisation of high-resolution residual terrain model (RTM) data for computing estimates of the omission error in rugged terrain. RTM elevations may be constructed as the difference between the SRTM (Shuttle Radar Topography Mission) elevation model and the DTM2006.0 spherical harmonic topographic expansion. Numerical tests, carried out in the German Alps with a precise gravimetric quasigeoid model (GCG05) and GPS/levelling data as references, demonstrate that RTM-based omission error estimatesimprove EGM2008 height anomaly differences by 10cm in many cases. The comparisons of EGM2008-only height anomalies and the GCG05 model showed 3.7 cm standard deviation after a bias-fit. Applying RTM omission error estimates to EGM2008 reduces the standard deviation to 1.9 cm which equates to a significant improvement rate of 47%. Using GPS/levelling data strongly corroborates thesefindings with an improvement rate of 49%. The proposed RTM approach may be of practical value to improve quasigeoid determination in mountainous areas without sufficient regional gravity data coverage, e.g., in parts of Asia, South America or Africa. As a further application, RTMomission error estimates will allow refined validation of global gravity field models like EGM2008 from GPS/levelling data

Data Analysis Techniques for Fan Performance in Highly-Distorted Flows from Boundary Layer Ingesting Inlets

The design of a unique distortion-tolerant fan for a high-bypass ratio boundary-layer ingesting propulsion system has been completed and a rig constructed and tested in the NASA Glenn 8x6 wind tunnel. Processing the data from the experiment presented some interesting challenges because of the complexity of the experimental setup and the flow through the test rig. The experiment was run in three phases, each of which employed a unique complement of inlet throat and fan face instrumentation to avoid the blockage that would have resulted from simultaneously installing all of the rakes. The measurement from the individual test points were subsequently combined to compute the overall stage performance. A CFD model of the experiment was used to gain understanding of the flow field and to test some of the techniques proposed for interpolating and extrapolating the measurements into regions where measurements were not made. This capability became extremely useful when it was discovered that there was an unexpected total temperature distortion in the tunnel. The CFD model was modified by inserting a total temperature profile at the upstream boundary that mimicked the measured distortion where measurements were available and that CFD solution was used to investigate methods to infer the complete total temperature field at the fan face

Accuracy analysis of vertical deflection data observed with the Hannover Digital Zenith Camera System TZK2-D

This paper analyses the accuracy of vertical deflection measurements carried out with the Digital Zenith Camera System TZK2-D, an astrogeodetic state-of-the-art instrumentation developed at the University of Hannover. During 107 nights over a period of 3.5 years, the system was used for repeated vertical deflection observations at a selected station in Hannover. The acquired data set consists of about 27,300 single measurements and covers 276 h of observation time, respectively. For the data collected at an earlier stage of development (2003 to 2004), the accuracy of the nightly mean values has been found to be about 0".10-0".12. Due to applying a refined observation strategy since 2005, the accuracy of the vertical deflection measurements was enhanced into the unprecedented range of 0".05-0".08. Accessing the accuracy level of 0".05 requires usually 1 h of observational data, while the 0".08 accuracy level is attained after 20 min measurement time. In comparison to the analogue era of geodetic astronomy, the accuracy of vertical deflection observations is significantly improved by about one order of magnitude

Mutual Validation of GNSS Height Measurements and High-precision Geometric-astronomical Leveling

The method of geometric-astronomical leveling is presented as a suited technique for the validation of GNSS (Global Navigation Satellite System) heights. In geometric-astronomical leveling, the ellipsoidal height differences are obtained by combining conventional spirit leveling and astronomical leveling. Astronomical leveling with recently developed digital zenith camera systems is capable of providing the geometry of equipotential surfaces of the gravity field accurate to a few 0.1 mm per km. This is comparable to the accuracy of spirit leveling. Consequently, geometric-astronomical leveling yields accurate ellipsoidal height differences that may serve as an independent check on GNSS height measurements at local scales. A test was performed in a local geodetic network near Hanover. GPS observations were simultaneously carried out at five stations over a time span of 48 h and processed considering state-of-the-art techniques and sophisticated new approaches to reduce station-dependent errors. The comparison of GPS height differences with those from geometric-astronomical leveling shows a promising agreement of some millimeters. The experiment indicates the currently achievable accuracy level of GPS height measurements and demonstrates the practical applicability of the proposed approach for the validation of GNSS height measurements as well as the evaluation of GNSS height processing strategies

Mechanism-controlled thermomechanical treatment of high manganese steels

Austenitic high manganese steels exhibit outstanding mechanical properties, such as high energy absorption, owing to various deformation-mechanisms such as dislocation slip, twinning-induced plasticity (TWIP) and transformation-induced plasticity (TRIP). Here, we show a novel thermomechanical treatment to manufacture a high manganese steel Fe–18Mn-0.3C (wt.-%) with excellent mechanical performance by combining these three deformation-mechanisms. This process of mechanism-controlled rolling resulted in ultra-high tensile strength of the high manganese steel up to 1.6 GPa, simultaneously with uniform elongations up to 15%.A thermomechanical process was developed to establish this combination of properties. Warm rolling was conducted at 200 °C, to suppress TRIP and activate TWIP as deformation mechanism. Thus, a high density of deformation twins and dislocations was introduced to the microstructure, avoiding martensite formation. During a subsequent recovery annealing at 520 °C or 550 °C, the dislocation density was reduced, yet the high density of deformation twins was preserved. The combination of warm rolling and recovery annealing resulted in an ultrafine microstructure with a high density of twins and moderate density of dislocations. The TRIP effect is predominant during plastic deformation at ambient conditions in the highly twinned microstructure. The resulting steel exhibits an ultra-high yield strength and sufficient ductility, favorable properties for lightweight construction in automotive or aerospace industry

Modulation of protein kinase C activity by NaF in bone marrow derived macrophages

AbstractStimulation of murine bone marrow derived macrophages with NaF, prelabeled with [1-14C]oleate and [3H]inositol, increased the production of inositol phosphates and the release of 1,2-[14C]diacylglycerol (DAG). Moreover, NaF also induced activation of protein kinase C. These results indicate that bone marrow derived macrophages exhibit a phosphatidyl-4,5-bisphosphate phospholipase C activity, sensitive to NaF, which might be modulated by G-proteins. Activation of protein kinase C could have been mediated by NaF-induced release of DAG

Expected accuracy of tilt measurements on a novel hexapod-based Digital zenith camera system: A Monte-Carlo simulation study

Digital zenith camera systems (DZCS) are dedicated astronomical-geodetic measurement systems for the observation of the direction of the plumb line. A DZCS key component is a pair of tilt meters for the determination of the instrumental tilt with respect to the plumb line. Highest accuracy (i.e., 0.1 arc-seconds or better) is achieved in practice through observation with precision tilt meters in opposite faces (180° instrumental rotation), and application of rigorous tilt reduction models. A novel concept proposes the development of a hexapod (Stewart platform)-based DZCS. However, hexapod-based total rotations are limited to about 30°–60° in azimuth (equivalent to ±15° to ±30° yaw rotation), which raises the question of the impact of the rotation angle between the two faces on the accuracy of the tilt measurement. The goal of the present study is the investigation of the expected accuracy of tilt measurements to be carried out on future hexapod-based DZCS, with special focus placed on the role of the limited rotation angle. A Monte-Carlo simulation study is carried out in order to derive accuracy estimates for the tilt determination as a function of several input parameters, and the results are validated against analytical error propagation.As the main result of the study, limitation of the instrumental rotation to 60° (30°) deteriorates the tilt accuracy by a factor of about 2 (4) compared to a 180° rotation between the faces. Nonetheless, a tilt accuracy at the 0.1 arc-second level is expected when the rotation is at least 45°, and 0.05 arc-second (about 0.25 microradian) accurate tilt meters are deployed. As such, a hexapod-based DZCS can be expected to allow sufficiently accurate determination of the instrumental tilt. This provides supporting evidence for the feasibility of such a novel instrumentation. The outcomes of our study are not only relevant to the field of DZCS, but also to all other types of instruments where the instrumental tilt must be corrected. Examples include electronic theodolites or total stations, gravity meters, and other hexapod-based telescopes

Evolution of Biological Bandages as First Cover for Burn Patients.

Significance: Cutaneous wound regeneration is vital to keep skin functions and for large wounds, to maintain human survival. In a deep burn, the ability of the skin to heal is compromised due to the damage of vasculature and resident cells, hindering a coordinated response in the regeneration process. Temporal skin substitutes used as first cover can play a major role in skin regeneration as they allow a rapid wound covering that, in turn, can significantly reduce infection risk, rate of secondary corrective surgeries, and indirectly hospitalization time and costs. Recent Advances: Skin was one of the first tissues to be bioengineered providing thus a skin equivalent; however, what is the current status subsequent to 40 years of tissue engineering? We review the classic paradigms of biological skin substitutes used as first cover and evaluate recent discoveries and clinical approaches adapted for burn injuries cover, with an emphasis on innovative cell-based approaches. Critical Issues: Cell-based first covers offer promising perspectives as they can have an active function in wound healing, such as faster healing minimizing scar formation and prepared wound bed for subsequent grafting. However, cell-based therapies encounter some limitations due to regulatory hurdles, as they are considered as "Advanced Therapy Medicinal Products," which imposes the same industry-destined good manufacturing practices as for pharmaceutical products and biological drug development. Future Directions: Further improvements in clinical outcome can be expected principally with the use of cell-based therapies; however, hospital exemptions are necessary to assure accessibility to the patient and safety without hindering advances in therapies