A sports headlight retrofitted on magnifying loupes: A simple and cheap method for daily use

Medical professionals such as doctors, nurses and paramedics often use headlight to examine or to perform surgical intervention in the patients. However, there are concerns related to its use such as comfort for the user, mobility and asepsis for the cable, availability in the departments plus cost effectiveness. The concept of a retrofitted 1-watt sports headlight (adjusted on magnifying loupes) would give quick access to a light source, be available and reliable at any place, save vital funds and would be environmentally friendly as the battery can be replaced. The same concept can be applied to pre-hospital emergency care and disaster medicine as well. BACKGROUND Headlights with fibre optic cables have being used for two decades as an adjunct to the operating theatre lighting. The cable-powered headlights pose, to our experience, some limitations for the operating team: Smooth personnel circulation around the operating field is hindered by repeated unplugging and re-plugging of the cable when surgeon and assistants change sides. Protocols for draping and asepsis have to accommodate the cumbersome cable and the light source and in addition are time consuming and arising issues of flexibility. The weight of the headlight and cable may cause health issues for the bearer (head ache, low back pain) [1]. Portable surgical headlights have also been available for the last decade for a not negligible cost. They are powered by a battery pack, attached to the torso/waist and connected to the headlight by a shorter cable. They are priced at hundreds of pounds. METHOD As an alternative to cumbersome cables and expensive ‘ad hoc’ designs, we use a retrofitted 1-watt sports headlight with a weight of 100 grams. We acquired that for $ 14.99 (approximately £10) from an outdoor specialist retailer (Petzl America, Clearfield, Utah, USA). The headlight is powered by three 1.5 Volt AAA batteries and provides 60 lumen of luminous flux (Fig.1). We have wrapped the elastic bands of the headlight around the corresponding horizontal (axial circumferential) and sagittal elements of the headband, where the magnifying loupes are mounted (Keeler Ltd., Clewer Hill Road, Windsor SL4 4AA). The headlight can be aimed by tilting the housing (Fig.1, 2). DISCUSSION The luminous flux from our headlight according to our experience in cardiothoracic surgery is adequate for a variety of procedures: femoral and axillary arterial access, harvesting internal thoracic (mammary) arteries, open pulmonary resections, valve surgery. Being fully portable without cable, light source or pouches, it is especially handy outside the operating suite (ITU, A&E, wards) for emergency re-explorations for bleeding, secondary wound closures, application of vacuum therapy dressings, trauma, for ECMO work etc. Finally, we have had no evidence of thermal injury, as has being reported from strong xenon beams [2]. This simple affordable headlight system can be easily adapted to the needs of the entire spectrum of surgical specialties, especially those using magnifying loupes. Therefore, can be part of basic life support kits for use in prehospital emergency care, disaster and military medicine [3]. The device has the following advantages: 1. ‘‘Two-in-one’’ function of Loupes and Torch. 2. Battery can be changed (so no need to throw away the item) and is environmentally friendly 3. No need for asepsis 4. Cost effective 5. Availability everywhere In conclusion, we believe this is a practical medical device

Magnetic levitation of large liquid volume

It is well known from experiments and industrial applications of cold crucible melting that an intense AC magnetic field can be used to levitate large volumes of liquid metal in the terrestrial conditions. The levitation confinement mechanism for large volumes of fluid is considerably different from the case of a small droplet, where surface tension plays a key role in constraining the liquid outflow at the critical bottom point. The dynamic interaction between the oscillatory motion of the free surface and the effects of turbulent flow is analysed using a unified numerical model, which describes the time dependent behaviour of the liquid metal and the magnetic field. The MHD modified k-? turbulence model is used to describe the mixing and damping properties at smaller scales not resolved by the macro model. The numerical multiphysics simulations suggest that it is possible to levitate a few kilograms of liquid metal in a cold crucible without requiring mechanical support from the container walls. Possible applications to the processing of reactive metals are discussed

Thermoelectric Magnetohydrodynamic effects on the crystal growth rate of undercooled Ni dendrites

In the undercooled solidification of pure metals, the dendrite tip velocity has been shown experimentally to have a strong dependence on the intensity of an external magnetic field, exhibiting several maxima and minima. In the experiments conducted in China, the undercooled solidification dynamics of pure Ni was studied using the glass fluxing method. Visual recordings of the progress of solidification are compared at different static fields up to 6 T. The introduction of microscopic convective transport through thermoelectric magnetohydrodynamics is a promising explanation for the observed changes of tip velocities. To address this problem, a purpose-built numerical code was used to solve the coupled equations representing the magnetohydrodynamic, thermal and solidification mechanisms. The underlying phenomena can be attributed to two competing flow fields, which were generated by orthogonal components of the magnetic field, parallel and transverse to the direction of growth. Their effects are either intensified or damped out with increasing magnetic field intensity, leading to the observed behaviour of the tip velocity. The results obtained reflect well the experimental findings. This article is part of the theme issue ‘From atomistic interfaces to dendritic patterns’

Use of a Static Magnetic Field in Measuring the Thermal Conductivity of a Levitated Molten Droplet

Numerical models are used to analyze the complex behaviour of magnetically levitated droplets in the context of determining their thermophysical properties. We focus on a novel method reported in Tsukada et al. [4] which uses periodic laser heating to determine the thermal conductivity of an electromagnetically levitated droplet in the presence of a static DC field to suppress convection. The results obtained from the spectral-collocation based free surface code SPHINX and the commercial package COMSOL independently confirm and extend previous findings in [4]. By including the effects of turbulence and movement of the free surface SPHINX can predict the behaviour of the droplet in dynamic regimes with and without the DC magnetic field. COMSOL is used to investigate arbitrary amplitude axial translational oscillations when the spherical droplet is displaced off its equilibrium. The results demonstrate that relatively small amplitude oscillations could cause significant variation in Joule heating and redistribution of the temperature. The effect of translational oscillations on the lumped circuit inductance is analysed. When a fixed voltage drive is applied across the terminals of the levitation coil, this effect will cause the coil current to change and a correction is needed to the electromagnetic force acting on the droplet

Vacuum arc remelting time dependent modelling

Vacuum arc remelting (VAR) aims at production of high quality, segregation-free alloys. The quality of the produced ingots depends on the operating conditions which could be monitored and analyzed using numerical modelling. The remelting process uniformity is controlled by critical medium scale time variations of the order 1-100 s, which are physically initiated by the droplet detachment and the large scale arc motion at the top of liquid pool [1,2]. The newly developed numerical modelling tools are addressing the 3-dimensional magnetohydrodynamic and thermal behaviour in the liquid zone and the adjacent ingot, electrode and crucible

Thin sample alloy solidification in electromagnetic driven convection

During the directional solidification of Ga-In25%wt., density variations in the liquid cause plumes of solute to be ejected from the interface through natural convection. This can lead to the formation of chimneys during solidification and ultimately freckles. The application of external magnetic fields can be used to suppress these plumes. Two magnetic systems are considered. The first is a rotating magnetic wheel, which provides conditions analogous to forced convection at the solidification interface. The forced convection causes preferential growth of secondary branches and causes the plumes to be transported downstream and back into the bulk. The second is through the application of a static magnetic field that interacts with inherent thermoelectric currents, generating a Lorentz force that drives fluid flow within the inter-dendritic region. However, in the bulk where there are no thermoelectric currents, electromagnetic damping dominates and plumes are stunted. Using a fully coupled transient numerical model each of these systems has been analysed. Comparisons to experiments are given for the cases of natural and forced convection. The experimental setup uses a Hele-Shaw cell with an electric heater and Peltier cooler, allowing for control over the thermal gradient and cooling rate

A fourth-order PDE denoising model with an adaptive relaxation method

In this paper, an adaptive relaxation method and a discontinuity treatment of edges are proposed to improve the digital image denoising process by using the fourth-order partial differential equation (known as the YK model) first proposed by You and Kaveh. Since the YK model would generate some speckles into the denoised image, a relaxation method is incorporated into the model to reduce the formation of isolated speckles. An additional improvement is employed to handle the discontinuity on the edges of the image. In order to stop the iteration automatically, a control of the iteration is integrated into the denoising process. Numerical results demonstrate that such modifications not only make the denoised image look more natural, but also achieve a higher value of PSNR

The association between IgG and IgM antibodies against cardiolipin, β2-glycoprotein I and Domain I of β2-glycoprotein I with disease profile in patients with multiple sclerosis

Antiphospholipid antibodies (aPL) occur in patients with multiple sclerosis (MS) with a number of studies reporting elevated levels; their exact prevalence and pathogenic role remain unclear. Epidemiological studies associate MS with an increased risk of deep venous thromboembolism and stroke; overlapping clinical features with APS. Antibodies against the first domain – Domain I (DI) – of β2glycoprotein I (β2GPI), show the most clinical significance and evidence for pathogenicity in the antiphospholipid syndrome (APS), but have not yet been investigated in MS. Serum from a well-defined cohort of 127 MS patients and 92 healthy controls were tested for IgM and IgG antibodies against cardiolipin (CL), β2GPI and DI. Higher frequency of IgM and IgG anti-CL were found in MS patients (18.1% and 21.3%), compared to controls (1.1% in both cases, p < 0.0001). We report that anti-DI antibodies were associated with MS patients, with 6.3% and 7.1% positive for IgM and IgG, respectively, compared to controls, 1.1% (p < 0.05). IgM anti-CL antibodies were elevated in secondary progressive MS and primary progressive MS compared to relapse-remitting MS, (p < 0.005). This study enrolled the largest number of patients with definite MS for studying the association with aPL. Although we confirmed IgM and IgG anti-CL antibodies occur in patients with MS, this is the first study that identified anti-DI antibodies in MS patients. This new finding may prove valuable and future studies are required to evaluate its role as a potential risk factor of thromboembolic phenomena in MS

The effects of natural, forced and thermoelectric magnetohydrodynamic convection during the solidification of thin sample alloys

Using a fully coupled transient 3-dimensional numerical model, the effects of convection on the microstructural evolution of a thin sample of Ga-In25%wt. was predicted. The effects of natural convection, forced convection and thermoelectric magnetohydrodynamics were investigated numerically. A comparison of the numerical results is made to experimental results for natural convection and forced convection. In the case of natural convection, density variations within the liquid cause plumes of solute to be ejected into the bulk. When forced convection is applied observed effects include the suppression of solute plumes, preferential secondary arm growth and an increase in primary arm spacing. These effects were observed both numerically and experimentally. By applying an external magnetic field inter-dendritic flow is generated by thermoelectrically induced Lorentz forces, while bulk flow experiences an electromagnetic damping force. The former causes preferential secondary growth, while the latter slows the formation of solute plumes. This work highlights that the application of external forces can be a valuable tool for tailoring the microstructure and ultimately the macroscopic material properties

Anti-factor Xa antibodies in patients with antiphospholipid syndrome and their effects upon coagulation assays

- Introduction: The aim of this study was to examine the prevalence and functional effects of antibodies directed against Factor (F)Xa and other serine proteases (SP) in patients with antiphospholipid syndrome (APS). - Methods: Serum from patients with APS (n = 59), systemic lupus erythematosus (SLE; n = 106), other autoimmune rheumatic disease (ARD; n = 63) and 40 healthy controls (HC) were tested for IgG activity against thrombin (Thr), FXa, FVIIa, phosphatidylserine (PS)/FXa and antithrombin (AT)-III by enzyme-linked immunosorbent assay (ELISA). Anti-FXa positive IgG were purified to measure their avidity by chaotropic ELISA and functional effects upon clotting time (FXa-ACT) and FXa enzymatic activity (± AT-III). - Results: Anti-FXa IgG were found in patients with SLE (49.1%) and APS (33.9%) (P <0.05) but not in ARD controls and HC. In contrast, anti-Thr and anti-PS/FXa IgG were identified in other ARD and anti-FVIIa IgG were low in all groups. The avidity of APS-IgG to FXa was significantly higher than SLE-IgG (P <0.05). Greatest prolongation of FXa-ACT was observed with APS-IgG and greatest inhibitory effect upon FXa enzymatic activity was found with APS-IgG followed by SLE-IgG compared to HC-IgG. ATIII inhibition of FXa was significantly reduced by APS-IgG compared with HC and SLE (P <0.05) and did not correlate with binding to AT-III. - Conclusion: APS anti-FXa IgG have higher avidity to FXa and greater effects upon the enzymatic and coagulant activity of FXa compared with SLE anti-FXa IgG. Further studies of anti-FXa antibodies in APS, SLE and other non-autoimmune thrombotic disease cohorts are now required to evaluate whether targeting FXa with selective inhibitors in patients bearing anti-FXa antibodies may be an effective treatment strategy