Assessment of left ventricular volumes using simplified 3-D echocardiography and computed tomography – a phantom and clinical study

<p>Abstract</p> <p>Objectives</p> <p>To compare the accuracy of simplified 3-dimensional (3-D) echocardiography vs. multi-slice computed tomography (MSCT) software for the quantification of left ventricular (LV) volumes.</p> <p>Design</p> <p>Three-D echocardiography (3-planes approach) and MSCT-CardIQ software were calibrated by measuring known volumes of 10 phantoms designed to closely mimic blood-endocardium interface. Subsequently, LV volumes were measured with both the methods in 9 patients referred routinely for coronary angiography and the agreement between the measurements was evaluated.</p> <p>Results</p> <p>Simplified 3D-echocardiography provided higher degree of agreement between the measured and true phantom volumes (mean difference 0 ± 1 ml, variation range +4 to -4 ml) than MSCT software (mean difference 6 ± 5 ml; variation range +22 to -10 ml). The agreement between LV measurements in the patients was considerably poorer, with significantly larger volumes produced by MSCT (mean difference -23 ± 40 ml, variation between +93 and -138 ml).</p> <p>Conclusion</p> <p>Simplified 3-D echocardiography provides more accurate assessment of phantom volumes than MSCT-CardIQ software. The discrepancy between the results of LV measurements with the two methods is even greater and does not warrant their interchangeable diagnostic use.</p

Robust T cell immunity in convalescent individuals with asymptomatic or mild COVID-19

SARS-CoV-2-specific memory T cells will likely prove critical for long-term immune protection against COVID-19. Here, we systematically mapped the functional and phenotypic landscape of SARS-CoV-2-specific T cell responses in unexposed individuals, exposed family members, and individuals with acute or convalescent COVID-19. Acute-phase SARS-CoV-2-specific T cells displayed a highly activated cytotoxic phenotype that correlated with various clinical markers of disease severity, whereas convalescent-phase SARS-CoV-2-specific T cells were polyfunctional and displayed a stem-like memory phenotype. Importantly, SARS-CoV-2-specific T cells were detectable in antibody-seronegative exposed family members and convalescent individuals with a history of asymptomatic and mild COVID-19. Our collective dataset shows that SARS-CoV-2 elicits broadly directed and functionally replete memory T cell responses, suggesting that natural exposure or infection may prevent recurrent episodes of severe COVID-19

Evaluation of Errors and Limitations in Ultrasound Imaging Systems

There are binding regulations requiring safety and efficacy aspects of medical devices. The requirements ask for documentation that the devices are safe and effective for their intended use, i.e. if a device has a measuring function it must be correct. In addition to this there are demands for quality systems describing development, manufacturing, labelling, and manufacturing of a device. The requirements are established to guarantee that non-defective medical devices are used in the routine clinical practice. The fast rates in which the imaging modalities have evolved during the last decades have resulted in numerous new diagnostic tools, such as velocity and deformation imaging in ultrasound imaging. However, it seems as if the development of evaluation methods and test routines has not been able to keep up the same pace. Two of the studies in this thesis, Study I and IV, showed that computed tomography-based and ultrasound based volume measurements can yield very disparate measurements, and that tissue Doppler imaging-based ultrasound measurements can be unreliable. Furthermore, the new ultrasound modalities impose higher demands on the ultrasound transducers. Transducers are known to be fragile, but defective transducers were less of a problem earlier when the ultrasound systems to a lesser extent were used for measurements. The two other studies, Study II and III, showed that serious transducer errors are very common, and that annual testing of the transducers is not sufficient to guarantee an error free function. The studies in the thesis indicate that the system with Notified Bodies, in accordance with the EU’s Medical Device Directive, checking the function and manufacturing of medical devices does not work entirely satisfactory. They also show that the evaluation of new methods have led to the undesirable situation, where new measuring tools, such as volume rendering from imaging systems, and tissue Doppler-based velocity and deformation imaging in echocardiography are available for clinicians without proven knowledge about their accuracy.QC 2011052

Bygg dig en konkursbuffert : - En studie om sex nyckeltal som kan innebära finansiell oro för små bolag inom byggbranschen

Denna studies syfte var att analysera sex nyckeltal och se vilka samband dessa hade på riskbuffert sysselsatt kapital. Studien utfördes på 796 små byggbolag i Sverige under perioden 2009–2016 med hjälp av en binär logistisk regressionsanalys. Som teoretisk referensram användes working capital management och finansiell oro. Studien resulterade i att kapitalets omsättningshastighet, skuldränta och rörelsekapital/totala tillgångar uppvisade signifikanta negativa samband med riskbuffert sysselsatt kapital. Räntetäckningsgrad och avkastning på totalt kapital resulterade i signifikanta positiva samband med riskbuffert sysselsatt kapital. Skuldsättningsgrad resulterade intressant nog i ett icke signifikant negativt samband. Slutligendiskuterades byggbolagens sannolikhet för finansiell oro utifrån respektive nyckeltal.The aim of this study was to examine the relation between six independent key ratios with riskbuffer on capital employed. The study was conducted on 796 small construction enterprises in Sweden during 2009–2016 with a binary logistic regression model. As theoretical framework, working capital management and financial distress was applied. The study concluded that the capital turnover rate, interest payable and working capital to total assets had significant negative relations with riskbuffer on capital employed. However, the interest cover ratio and return on total assets were both significant positively related withriskbuffer on capital employed. Debt-to-equity ratio resulted interestly enough in a nonsignificant negative relation. Lastly, with regards taken to every respective key ratio, the probability of financial distress among the construction firms was discussed

Understanding and influencing teaching and learning cultures at university - A network approach

Academic cultures might be perceived as conservative, at least in terms of development of teaching and learning. Through a lens of network theory this conceptual article analyses the pattern of pathways in which culture is constructed through negotiation of meaning. The perspective contributes to an understanding of culture construction and maintenance with a potential to aid academic developers and others in the endeavour to influence teaching and learning cultures in academia. Throughout the discussion the importance of supporting the weak links between clusters of individuals stands out as a feature to focus upon. We propose that the sheer complexity of culture construction and maintenance in academic organisations is likely to cause any single, isolated attempt for change to fail Instead, we argue that a multitude of inter-related initiatives over a long period of time is likely to distinguish strategies that are successful in influencing academic teaching and learning cultures

The Effect of Ankle Foot Orthosis' Design and Degree of Dorsiflexion on Achilles Tendon Biomechanics : Tendon Displacement, Lower Leg Muscle Activation, and Plantar Pressure During Walking

Background: Following an Achilles tendon rupture, ankle foot orthoses (AFO) of different designs are used to protect the healing tendon. They are generally designed to protect against re-rupture by preventing undesired dorsiflexion and to prevent elongation by achieving plantarflexion in the ankle. There is limited knowledge of the biomechanical effects of different AFO designs and ankle angles on the tendon and lower leg muscles.Hypothesis: The hypothesis was that non-uniform displacement in the Achilles tendon, lower leg muscle activity, and plantar pressure distribution would be affected differently in different designs of AFO and by varying the degree of dorsiflexion limitation.Study Design: Controlled laboratory study.Methods: Ultrasound of the Achilles tendon, EMG of the lower leg muscles and plantar pressure distribution were recorded in 16 healthy subjects during walking on a treadmill unbraced and wearing three designs of AFO. Ultrasound speckle tracking was used to estimate motion within the tendon. The tested AFO designs were a rigid AFO and a dorsal brace used together with wedges and an AFO with an adjustable ankle angle restricting dorsiflexion to various degrees.Results: There were no significant differences in non-uniform tendon displacement or muscle activity between the different designs of AFO. For the rigid AFO and the adjustable AFO there was a significant reduction in non-uniform displacement within the tendon and soleus muscle activity as restriction in dorsiflexion increased.Conclusion: The degree of dorsiflexion allowed within an AFO had greater effects on Achilles tendon displacement patterns and muscle activity in the calf than differences in AFO design. AFO settings that allowed ankle dorsiflexion to neutral resulted in displacement patterns in the Achilles tendon and muscle activity in the lower leg which were close to those observed during unbraced walking

Temperature dependence of electronic coupling through oligo-p-phenyleneethynylene bridges

A series of donor-bridge-acceptor (D-B-A) systems with varying donor–acceptor distances has been studied with respect to the temperature dependence of the triplet excitation energy transfer (TEET) rates. The donor and acceptor, zinc(II) and free-base porphyrin, respectively, were separated by oligo-p-phenyleneethynylene (OPE) bridges, where the number of phenyleneethynylene groups was varied between two and five, giving rise to edge-to-edge separations ranging between 12.7 and 33.4 Å. The study was performed in 2-MTHF between room temperature and 80 K. It was found that the distance dependence was exponential, in line with the McConnell model, and the attenuation factor, β, was temperature dependent. The experimentally determined temperature dependence of β was evaluated by using a previously derived model for the conformational dependence of the electronic coupling based on results from extensive quantum chemical, DFT and time-dependent DFT (TD-DFT), calculations. Two regimes in the temperature interval could be identified: one high-temperature, low-viscosity regime, and one low-temperature, high-viscosity regime. In the first regime, the temperature dependence of β was, according to the model, well described by a Boltzmann conformational distribution. In the latter, the molecular motions that govern the electronic coupling are slowed down to the same order of magnitude as the TEET rates. This, in effect, leads to a distortion of the conformational distribution. In the high-temperature regime the model could reproduce the temperature dependence of β, and the extracted rotational barrier between two neighboring phenyl units of the bridge structure, Ei=1.1 kJ mol−1, was in line with previous experimental and theoretical studies. After inclusion of parameters that take the viscosity of the medium into account, successful modeling of the experimentally observed temperature dependence of the distance dependence was achieved over the whole temperature interval

VMI – Vem tar initiativet, varför och vad leder det till för samarbete?

Med större krav på effektivisering och pressade kostnader har VMI på senare tid blivit en allt mer tillämpad metod för att samordna aktiviteterna i försörjningskedjan. Mycket forskning har gjorts kring ämnet VMI och dess fördelar. Däremot har inte mycket skrivits om initiativtagande och hur dessa samarbeten uppstår. Syftet med uppsatsen är att undersöka företag som tillämpar VMI. Detta för att ta reda på vem, kunden eller leverantören, som tar initiativet till samarbetet och varför. Utifrån detta vill vi även identifiera konsekvenser kopplade till vem som tog initiativet. Genom vår undersökning har vi kommit fram till att kunden så väl som leverantören kan vara initiativtagare. Detta för att det finns vinster att göras för båda parter. Vi har kunnat identifiera att den främsta anledningen till initiativtagande är de fördelar som ses för det egna företaget. En annan bidragande faktor är även att företagen vill skapa långsiktiga relationer. Vi har genom vår studie inte kunnat identifiera några konsekvenser i samarbetet som är direkt kopplade till vem som tar initiativet. Däremot har vi sett indikationer på att den part som tar initiativet är den som ofta bäst lyckas påverka villkoren för samarbetet

Evaluation of ultrasound Tissue Velocity Imaging : a phantom study of velocity estimation in skeletal muscle low-level contractions

Background: Tissue Velocity Imaging (TVI) is an ultrasound based technique used for quantitative analysis of the cardiac function and has earlier been evaluated according to myocardial velocities. Recent years several studies have reported applying TVI in the analysis of skeletal muscles. Skeletal tissue velocities can be very low. In particular, when performing isometric contractions or contractions of low force level the velocities may be much lower compared to the myocardial tissue velocities. Methods: In this study TVI was evaluated for estimation of tissue velocities below the typical myocardial velocities. An in-house phantom was used to see how different PRF-settings affected the accuracy of the velocity estimations. Results: With phantom peak velocity at 0.03 cm/s the error ranged from 31% up to 313% with the different PRF-settings in this study. For the peak velocities at 0.17 cm/s and 0.26 cm/s there was no difference in error with tested PFR settings, it is kept approximately around 20%. Conclusions: The results from the present study showed that the PRF setting did not seem to affect the accuracy of the velocity estimation at tissue velocities above 0.17 cm/s. However at lower velocities (0.03 cm/s) the setting was crucial for the accuracy. The PRF should therefore preferable be reduced when the method is applied in low-level muscle contraction

Diastereomeric bactericidal effect of Ru(phenanthroline) 2 dipyridophenazine

ABSTRACT Metal susceptibility assays and spot plating were used to investigate the antimicrobial activity of enantiopure [Ru(phen