1,223 research outputs found

    Thermodynamic properties of 2-methyl lactic acid

    Get PDF
    © 2018 Elsevier Ltd The measurements of the values of the enthalpy of formation, vaporisation, sublimation and fusion of 2-methyl lactic acid have been performed using methods of combustion calorimetry, transpiration method and differential scanning calorimetry. A conformational analysis has been conducted to identify a set of stable conformers of the compound. Methods of statistical thermodynamics have been used to calculate the thermodynamic functions of the acid in the ideal gas state considering the contribution of the internal rotation in “rigid rotator – anharmonic oscillator” approximation within temperature interval (298.15–1500) К for the conformers under study

    Diffraction based Hanbury Brown and Twiss interferometry performed at a hard x-ray free-electron laser

    Full text link
    We demonstrate experimentally Hanbury Brown and Twiss (HBT) interferometry at a hard X-ray Free Electron Laser (XFEL) on a sample diffraction patterns. This is different from the traditional approach when HBT interferometry requires direct beam measurements in absence of the sample. HBT analysis was carried out on the Bragg peaks from the colloidal crystals measured at Linac Coherent Light Source (LCLS). We observed high degree (80%) spatial coherence of the full beam and the pulse duration of the monochromatized beam on the order of 11 fs that is significantly shorter than expected from the electron bunch measurements.Comment: 32 pages, 10 figures, 2 table

    Complications of fixed infrared emitters in computer-assisted total knee arthroplasties

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>The first stage in the implant of a total knee arthroplasty with computer-assisted surgery is to fasten the emitters to the femur and the tibia. These trackers must be hard-fixed to the bone. The objectives of our study are to evaluate the technical problems and complications of these tracker-pins, the necessary time to fix them to the bone and the possible advantages of a new femoral-fixed tracker-pin.</p> <p>Methods</p> <p>Three hundred and sixty seven tracker-pins were used in one hundred and fifty one computer-assisted total knee replacements. A bicortical screw was used to fix the tracker to the tibia in all cases; in the femur, however, a bicortical tracker was used in 112 cases, while a new device (OrthoLock) with percutaneous fixation pins was employed in the remaining 39.</p> <p>Results</p> <p>Technical problems related to the fixing of the trackers appeared in nine cases (2.5%). The mean surgery time to fix the tracker pin to the tibia was 3 minutes (range 2–7), and 5 minutes in the case of the femoral pin (range: 4–11), although with the new tool it was only three minutes (range 2–4) (p < 0.001). No complications were observed with this new device.</p> <p>Conclusion</p> <p>The incidence of problems and complications with the fixing systems used in knee navigation is very small. The use of a new device with percutaneous pins facilitates the fixing of femoral trackers and decreases the time needed to place them.</p

    The effect of experimental hyperoxia on erythrocytes’ oxygen-transport function

    Get PDF
    The aim of this study was to investigate the effect of hyperoxia, calcium ions and pH value on the composition of major phospholipids in human erythrocyte membranes and erythrocytes’ oxygen-transport function. To create a model of hyperoxia, we saturated the incubated mixture with oxygen by constant passing of oxygen–air mixture through the incubation medium. To assess the effect of elevated calcium ion concentrations, CaCl2 was added to the incubation medium. An incubation medium with different pH was used to study the effect of various pH values. Lipids were extracted from erythrocytes and chromatographic separation was carried out in a thin layer of silica gel deposited on a glass plate. The thiobarbituric acid (TBA)-active products and the content of diene conjugates (DC) in erythrocytes were determined. The oxygen-binding capacity of haemoglobin was evaluated using Raman spectroscopy. The obtained results indicated that hyperoxia causes deep changes both in the composition and character of bilayer lipids of erythrocyte membranes, which affects the functional characteristics of erythrocytes, primarily the oxygen-transport properties of erythrocyte haemoglobin. It should be noted that a combination of Ca2+ ions and change in the pH value intensify the processes associated with disruption of phospholipids’ composition. The findings indicate that the lipid phase is one of the key elements in the functioning of erythrocytes in norm as well as during development of various pathological processes

    A 3D computed tomography based tool for orthopedic surgery planning

    Get PDF
    Series : Lecture notes in computational vision and biomechanics, vol. 19The preparation of a plan is essential for a surgery to take place in the best way possible and also for shortening patient’s recovery times. In the orthopedic case, planning has an accentuated significance due to the close relation between the degree of success of the surgery and the patient recovering time. It is important that surgeons are provided with tools that help them in the planning task, in order to make it more reliable and less time consuming. In this paper, we present a 3D Computed Tomography based solution and its implementation as an OsiriX plugin for orthopedic surgery planning. With the developed plugin, the surgeon is able to manipulate a three-dimensional isosurface rendered from the selected imaging study (a CT scan). It is possible to add digital representations of physical implants (surgical templates), in order to evaluate the feasibility of a plan. These templates are STL files generated from CAD models. There is also the feature to extract new isosurfaces of different voxel values and slice the final 3D model according to a predefined plane, enabling a 2D analysis of the planned solution. Finally, we discuss how the proposed application assists the surgeon in the planning process in an alternative way, where it is possible to three-dimensionally analyze the impact of a surgical intervention on the patient.(undefined

    MOCDroid: multi-objective evolutionary classifier for Android malware detection

    Get PDF
    Malware threats are growing, while at the same time, concealment strategies are being used to make them undetectable for current commercial Anti-Virus. Android is one of the target architectures where these problems are specially alarming, due to the wide extension of the platform in different everyday devices.The detection is specially relevant for Android markets in order to ensure that all the software they offer is clean, however, obfuscation has proven to be effective at evading the detection process. In this paper we leverage third-party calls to bypass the effects of these concealment strategies, since they cannot be obfuscated. We combine clustering and multi-objective optimisation to generate a classifier based on specific behaviours defined by 3rd party calls groups. The optimiser ensures that these groups are related to malicious or benign behaviours cleaning any non-discriminative pattern. This tool, named MOCDroid, achieves an ac-curacy of 94.6% in test with 2.12% of false positives with real apps extracted from the wild, overcoming all commercial Anti-Virus engines from VirusTotal

    Probabilities from Entanglement, Born's Rule from Envariance

    Full text link
    I show how probabilities arise in quantum physics by exploring implications of {\it environment - assisted invariance} or {\it envariance}, a recently discovered symmetry exhibited by entangled quantum systems. Envariance of perfectly entangled ``Bell-like'' states can be used to rigorously justify complete ignorance of the observer about the outcome of any measurement on either of the members of the entangled pair. For more general states, envariance leads to Born's rule, pkψk2p_k \propto |\psi_k|^2 for the outcomes associated with Schmidt states. Probabilities derived in this manner are an objective reflection of the underlying state of the system -- they represent experimentally verifiable symmetries, and not just a subjective ``state of knowledge'' of the observer. Envariance - based approach is compared with and found superior to pre-quantum definitions of probability including the {\it standard definition} based on the `principle of indifference' due to Laplace, and the {\it relative frequency approach} advocated by von Mises. Implications of envariance for the interpretation of quantum theory go beyond the derivation of Born's rule: Envariance is enough to establish dynamical independence of preferred branches of the evolving state vector of the composite system, and, thus, to arrive at the {\it environment - induced superselection (einselection) of pointer states}, that was usually derived by an appeal to decoherence. Envariant origin of Born's rule for probabilities sheds a new light on the relation between ignorance (and hence, information) and the nature of quantum states.Comment: Figure and an appendix (Born's rule for continuous spectra) added. Presentation improved. (Comments still welcome...
    corecore