Dynamic behavior of eye globes

Spherical shell equations and inertia terms for dynamic behavior of eye globe

Determination of mechanical properties of excised dog radii from lateral vibration experiments

Experimental data which can be used as a guideline in developing a mathematical model for lateral vibrations of whole bone are reported. The study used wet and dry dog radii mounted in a cantilever configuration. Data are also given on the mechanical, geometric, and viscoelastic properties of bones

Estimation of left ventricular volume from apical orthogonal 2-D echocardiograma

In 42 consecutive patients undergoing biplane left ventricular cine-angiography, left ventricular volumes were first determined ultrasonically using a phased array transducer. To this end, two orthogonal apical long axis views were recorded one illustrating all four chambers, the other being the ‘RA O equivalent' view. Left ventricular volumes wer estimated by applying the area-length method to both two-dimensional echocardiograms and cine-angiograms, consistently including in the former the left ventricular outflow tract of the ‘RAO equivalent' view. The echocardiographic approach employed was shown to yield good predictions of the angiographic results. For the end-diastolic volume the correlation is characterized by r=0.98 and SEE 21 ml or 9.7% of the angiographic mean and for the end-systolic volume by r=0.97 and SEE 17 ml or 18.1% of the mean. The correlation for the ejection fraction showed an r value of 0.87 and a SEE of 5.4%. Equally good correlations were obtained in the subgroup with wall motion disorders for which the r values of the end-diastolic and end-systolic volumes were both 0.98 and that of the ejection fraction was 0.8

Dynamics of aortic flow in hypertrophic cardiomyopathy

The purpose of this study was to reassess left ventricular ejection dynamics in hypertrophic cardiomyopathy, to investigate whether a premature stoppage of ejection occurs, as previously reported, and whether reliable criteria for left ventricular outflow tract obstruction can be established by non-invasive evaluation of aortic flow patterns. In a group of 21 patients with hypertrophic cardiomyopathy, composed of 9 with the obstructive form (HOCM), 9 with the non-obstructive form (HNCM) and 3 with apical hypertrophy (HACM), instantaneous flow velocities across the ascending aorta were determined non-invasively with a 16-gated Doppler 2-D echo instrument. Ten normals served as controls. The 16 flow velocities were averaged over 8 heart beats and the relative volume flow rate was calculated by microprocessor analysis. Ejection time (i.e. flow time) derived from the flow curves was compared with the available ejection period as determined from the carotid pulse tracing. In normals, ejection time amounted to 94±3% of the available ejection period, in HOCM to 92±5% and in HNCM to 93±4% (no significant differences). In HACM, however, ejection time was reduced to 71±14% of the available ejection period. In contrast to HNCM, aortic flow in HOCM was characterized by an early peak followed by a plateau at a sizeably lower flow level for the rest of systole. Flow time of an abnormally short duration was the hallmark of HACM. We conclude that in patients with hypertrophic cardiomyopathy, HOCM and HNCM can be distinguished by the shape of their volume flow curves. A premature stoppage of ejection is only found in patients with HAC

A comparison between single gate and multigate ultrasonic Doppler measurements for the assessment of the velocity pattern in the human ascending aorta

The velocity pattern in the ascending aorta of 15 healthy adults was measured quasisimultaneously from the Doppler-shifts produced in 16 gates distributed equally within the cross-section along a narrow ultrasound beam which centrally traversed the vessel upstream of the brachiocephalic trunk. A comparison between the time integrals of the velocities in gates 9 (centre line), 4 and 13 (off centre) and the time integral of the weighted mean of the velocities of all gates correlated with r=0.90, SEE=1.05 (gate 9), r=0.90, SEE 0.88 (gate 4) and r=0.92, SEE 0.94 (gate 13). A better correlation (r=0.96, SEE=0.60) was found between the linear mean of all gates and the weighted mean. These results show that Doppler measurements in single small gates are not appropriate to determine the average cross-sectional blood flow velocity in healthy adult

Potential role of coronary vasoconstriction in ischaemic heart disease: effect of exercise

Coronary vasomotion plays an important role in the regulation of coronary perfusion at rest and during exercise. Normal coronary arteries show coronary vasodilation of the proximal (+20%) and distal (+40%) vessel segments during supine bicycle exercise. However, patients with coronary artery disease show exercise-induced vasoconstriction of the stenotic vessel segments. The exact mechanism of exercise-induced stenosis narrowing is not clear but might be related to a passive collapse of the disease-free vessel wall (Venturi mechanism), elevated plasma levels of circulating catecholamines, an insufficient production of the endothelium-derived vesorelaxing factor or increased platelet aggregation due to turbulent blood flow with release of thromboxane A2 and serotonin. Various vasoactive drugs, such as nitroglycerin and calcium antagonists, prevent exercise-induced stenosis vasoconstriction. An additive effect on coronary vasodilation of the stenotic vessel segment was observed after combination of nitroglycerin with diltiazem. Thus, exercise-induced stenosis narrowing plays an important role in the pathophysiology of myocardial ischaemia during dynamic exercise. The antianginal effect of vasoactive substances can be explained—besides the effect on pre- and afterload—by a direct action on coronary stenosis vasomotio

Effects of Multi-Surface Modification on Curie temperature of ferroelectric films

Within the framework of mean field theory, we study the effects of multi-surface modification on Curie temperature of ferroelectric films using the transverse Ising model. The general nonlinear equations for Curie temperature of multi-surface ferroelectric films with arbitrary exchange constants and transverse fields are derived by the transfer matrix method. As an example, we consider a film consisting of top surface layers, bulk layers and bottom surface layers. Two types of surface modifications, modifications of a surface exchange constant and a surface transverse field are taken into account. The dependence of Curie temperature on the surface layer numbers, bulk layer numbers, surface exchange constants, surface transverse fields and bulk transverse fields is discussed.Comment: 11 pages, 5 figure

Swiss clinical practice guidelines on field cancerization of the skin.

Actinic keratosis (AK) affects millions of people worldwide, and its prevalence continues to increase. AK lesions are caused by chronic ultraviolet radiation exposure, and the presence of two or more AK lesions along with photodamage should raise the consideration of a diagnosis of field cancerization. Effective treatment of individual lesions as well as field cancerization is essential for good long-term outcomes. The Swiss Registry of Actinic Keratosis Treatment (REAKT) Working Group has developed clinical practice guidelines for the treatment of field cancerization in patients who present with AK. These guidelines are intended to serve as a resource for physicians as to the most appropriate treatment and management of AK and field cancerization based on current evidence and the combined practical experience of the authors. Treatment of AK and field cancerization should be driven by consideration of relevant patient, disease, and treatment factors, and appropriate treatment decisions will differ from patient to patient. Prevention measures and screening recommendations are discussed, and special considerations related to management of immunocompromised patients are provided

Temperature Evolution of Sodium Nitrite Structure in a Restricted Geometry

The NaNO$_{2}$ nanocomposite ferroelectric material in porous glass was studied by neutron diffraction. For the first time the details of the crystal structure including positions and anisotropic thermal parameters were determined for the solid material, embedded in a porous matrix, in ferro- and paraelectric phases. It is demonstrated that in the ferroelectric phase the structure is consistent with bulk data but above transition temperature the giant growth of amplitudes of thermal vibrations is observed, resulting in the formation of a "premelted state". Such a conclusion is in a good agreement with the results of dielectric measurements published earlier.Comment: 4 pages, 4 figure

CD20 and CD19 targeted vectors induce minimal activation of resting B lymphocytes

B lymphocytes are an important cell population of the immune system. However, until recently it was not possible to transduce resting B lymphocytes with retro- or lentiviral vectors, making them unsusceptible for genetic manipulations by these vectors. Lately, we demonstrated that lentiviral vectors pseudotyped with modified measles virus (MV) glycoproteins hemagglutinin, responsible for receptor recognition, and fusion protein were able to overcome this transduction block. They use either the natural MV receptors, CD46 and signaling lymphocyte activation molecule (SLAM), for cell entry (MV-LV) or the vector particles were further modified to selectively enter via the CD20 molecule, which is exclusively expressed on B lymphocytes (CD20-LV). It has been shown previously that transduction by MV-LV does not induce B lymphocyte activation. However, if this is also true for CD20-LV is still unknown. Here, we generated a vector specific for another B lymphocyte marker, CD19, and compared its ability to transduce resting B lymphocytes with CD20-LV. The vector (CD19ds-LV) was able to stably transduce unstimulated B lymphocytes, albeit with a reduced efficiency of about 10% compared to CD20-LV, which transduced about 30% of the cells. Since CD20 as well as CD19 are closely linked to the B lymphocyte activation pathway, we investigated if engagement of CD20 or CD19 molecules by the vector particles induces activating stimuli in resting B lymphocytes. Although, activation of B lymphocytes often involves calcium influx, we did not detect elevated calcium levels. However, the activation marker CD71 was substantially up-regulated upon CD20-LV transduction and most importantly, B lymphocytes transduced with CD20-LV or CD19ds-LV entered the G1b phase of cell cycle, whereas untransduced or MV-LV transduced B lymphocytes remained in G0. Hence, CD20 and CD19 targeting vectors induce activating stimuli in resting B lymphocytes, which most likely renders them susceptible for lentiviral vector transduction