Review of a frugal cooling mattress to induce therapeutic hypothermia for treatment of hypoxic-ischaemic encephalopathy in the UK NHS

Hypoxic ischaemic encephalopathy (HIE) is a major cause of neonatal mortality and disability in the United Kingdom (UK) and has significant human and financial costs. Therapeutic hypothermia (TH), which consists of cooling down the newborn’s body temperature, is the current standard of treatment for moderate or severe cases of HIE. Timely initiation of treatment is critical to reduce risk of mortality and disability associated with HIE. Very expensive servo-controlled devices are currently used in high-income settings to induce TH, whereas low-income settings rely on the use of low-tech devices such as water bottles, ice packs or fans. Cooling mattresses made with phase change materials (PCMs) were recently developed as a safe, efficient, and affordable alternative to induce TH in low-income settings. This frugal innovation has the potential to become a reverse innovation for the National Health Service (NHS) by providing a simple, efficient, and cost-saving solution to initiate TH in geographically remote areas of the UK where cooling equipment might not be readily available, ensuring timely initiation of treatment while waiting for neonatal transport to the nearest cooling centre. The adoption of PCM cooling mattresses by the NHS may reduce geographical disparity in the availability of treatment for HIE in the UK, and it could benefit from improvements in coordination across all levels of neonatal care given challenges currently experienced by the NHS in terms of constraints on funding and shortage of staff. Trials evaluating the effectiveness and safety of PCM cooling mattresses in the NHS context are needed in support of the adoption of this frugal innovation. These findings may be relevant to other high-income settings that experience challenges with the provision of TH in geographically remote areas. The use of promising frugal innovations such as PCM cooling mattresses in high-income settings may also contribute to challenge the dominant narrative that often favours innovation from North America and Western Europe, and consequently fight bias against research and development from low-income settings, promoting a more equitable global innovation landscape

Cholesterol crystal embolism (atheroembolism)

Cholesterol crystal embolism, known as atheroembolic disease, is caused by showers of cholesterol crystals from an atherosclerotic plaque that occludes small arteries. Embolization can occur spontaneously or as an iatrogenic complication from an invasive vascular procedure (angiography or vascular surgery) and after anticoagulant therapy. The atheroembolism can give rise to different degrees of renal impairment. Some patients show a moderate loss of renal function, others severe renal failure requiring dialysis. Renal outcome can be variable: some patients deteriorate or remain on dialysis, some improve and some remain with chronic renal impairment. Clinically, three types of atheroembolic renal disease have been described: acute, subacute or chronic. More frequently a progressive loss of renal function occurs over weeks. Atheroembolization can involve the skin, gastrointestinal system and central nervous system. The diagnosis is difficult and controversial for the protean extrarenal manifestations. In the past, the diagnosis was often made post-mortem. In the last 10 yrs, awareness of atheroembolic renal disease has improved. The correct diagnosis requires the clinician to be alert. The typical patient is a white male aged >60 yrs with a history of hypertension, smoking and arterial disease. The presence of a classic triad (precipitating event, renal failure and peripheral cholesterol crystal embolization) suggests the diagnosis. This can be confirmed by a biopsy of the target organs. A specific treatment is lacking; however, it is an important diagnosis to make because an aggressive therapeutic approach can be associated with a more favorable clinical outcome

Contribución al diseño de convertidores de tipo elevador-reductor para alimentación de sistemas de iluminación en leds.

.En aquesta tesis doctoral es presenta el disseny i implementació d’un sistema d’alimentació ac-dc basat en convertidors de tipus elevador-reductor d’única etapa. El sistema s’ha dissenyat per regular el corrent d’alimentació d’un conjunt de LEDs connectats en sèrie. El sistema d’alimentaciódissenyat té la capacitat de mantenir constant el flux lumínic dels LEDs i permet la dimerització en un ampli rang de valors de corrent. Simultàniament, el sistema manté un nivell molt baix d’harmònics introduïts a la xarxa de corrent altern. L’anàlisi ha demostrat la viabilitat en l’aplicació del control en mode lliscant per a la imposició d’un comportament como resistor lliure de pèrdues (LFR) en convertidors de tipus elevador-reductor d’ordre elevat (Ćuk, SEPIC i Shepard-Taylor) en els que es pretengui simultàniament regular el corrent de sortida. En aquest context, s’ha exposat en detall l’anàlisi dinàmic, i posterior disseny del llaç de regulació de corrent, del LFR basat en el convertidor Ćuk quan s’alimenta a través d’una font de corrent alterna de 230 Vrms-50 Hz. Un dels problemes trobats ha estat l’aparició de distorsió a la forma d’ona del corrent d’entrada en els passos per zero. Aquesta distorsió impedeix, per baixes potències d’entrada, el compliment de la norma d’introducció d’harmònics i, per tant, limita el seu ús en aplicacions de dimerització. S’ha proposat una solució basada en la modulació de la finestra d’histèresi de tal forma que a la proximitat del pas per zero la freqüència de commutació del convertidor augmenta. Mitjançant aquesta tècnica es garanteix tant el compliment de las normes preceptives com un rang de dimerització del 0 al 100 %. Las previsions teòriques s’han verificat mitjançant simulació i a partir de prototipus experimentals.En esta tesis doctoral se presenta el diseño e implementación de un sistema de alimentación AC-DC basado en convertidores de tipo elevador-reductor de única etapa. El sistema se ha diseñado para regular la corriente de alimentación de un conjunto de LEDs conectados en serie. Este tiene la capacidad de mantener constante el flujo lumínico de los LEDs y permite la dimerización en un amplio rango de valores de corriente. Simultáneamente, el sistema mantiene un nivel muy bajo de armónicos introducidos a la red de corriente alterna. El análisis ha demostrado la viabilidad en la aplicación del control en modo deslizante para la imposición de un comportamiento como resistor libre de pérdidas (LFR) en convertidores de tipo elevador-reductor de orden elevado (Ćuk, SEPIC y Shepard-Taylor) en los que se pretenda simultáneamente regular la corriente de salida. En este contexto, se ha expuesto en detalle el análisis dinámico, y posterior diseño del lazo de regulación de corriente, del LFR basado en el convertidor Ćuk cuando se alimenta a través de una fuente de corriente alterna de 230 Vrms-50 Hz. Uno de los problemas encontrados ha sido la aparición de distorsión en la forma de onda de la corriente de entrada en los cruces por cero. Dicha distorsión impide, para bajas potencias de entrada, el cumplimiento de la norma de introducción de armónicos y, por tanto, limita su utilización para aplicaciones de dimmerización. Se ha propuesto una solución basada en modulación de la ventana de histéresis de tal forma que en las cercanías del cruce por cero la frecuencia de conmutación del convertidor aumenta. Mediante esta técnica se garantiza tanto el cumplimiento de las normas preceptivas como un rango de dimerización del 0 al 100 %. Las previsiones teóricas se han verificado mediante simulación y a partir de prototipos experimentales.In this thesis, the design and implementation of an ac-dc power factor correction system based on single-stage step up/down converters is presented. The system has been designed to regulate the supply current of a string of LEDs connected in series. The driver has the capability to maintain a constant luminous flux and to dimmer the LED in a wide range of current values. Simultaneously, the system maintains a very low level of current harmonics introduced into the AC mains. The analysis has demonstrated the feasibility in applying the sliding mode control for imposing simultaneously, at single-stage high-order converters (Ćuk, SEPIC and Shepard-Taylor), a Loss-Free Resistor (LFR) behavior and a regulated output current. In this context, it has been exposed in detail the dynamic analysis and the design of a current regulation loop for a Ćuk-based LFR supplied from a AC voltage source of 230 Vrms-50 Hz. One of the problems identified has been the presence of distortion in the input current waveform at the zero crossings. Such distortion prevents, for low input powers, the harmonics compliance and therefore limits their use in LED dimming. To overcome this problem, it has been proposed a technique, based on a variable hysteresis window, to improve the performance near the zero crossing of the input current. This improvement is achieved by increasing the switching frequency near this zero crossing region. With this technique, the dimming range goes from 0-100% maintaining at the same time very low harmonic distortion at the input current. Moreover, experimental and computer simulation results presented are given in order to verify the theoretical predictions

Surface disinfection: evaluation of the efficacy of a nebulization system spraying hydrogen peroxide

Introduction. The study assessed the efficacy of a system of nebulization of a hydrogen peroxide-based solution for surface disinfection. Methods. Different concentrations (1, 2 and 4 ml/m3) of the same disinfectant solution (active principle: hydrogen peroxide) were nebulized inside a 50 m3 experimental environment. Sampling was carried out on both horizontal and vertical surfaces, and the total bacterial load at 37 °C was determined by means of direct contact with Rodac plates. The disinfection efficacy of the system was evaluated by comparing the total bacterial load measured on the surfaces before and after treatment. Statistical analysis was performed by means of Stata/SE9® software. Results. The percentage reduction in the mean bacterial load on horizontal surfaces as a result of treatment at concentrations of 1, 2 and 4 ml/m3 proved to be 54.9%, 70.9% and 86.9%, respec- tively. With regard to vertical surfaces, the percentage reduction was 100% in all experimental conditions. Discussion and conclusions. The system tested proved to be efficacious in disinfecting surfaces inside environments of 50 m3 in volume. It could therefore be used to disinfect surfaces in hos- pital and community settings. In healthcare facilities, disinfection by means of nebulization systems could help to reduce the risk of spreading nosocomial infections

Coherent ultrafast spin-dynamics probed in three dimensional topological insulators

Topological insulators are candidates to open up a novel route in spin based electronics. Different to traditional ferromagnetic materials, where the carrier spin-polarization and magnetization are based on the exchange interaction, the spin properties in topological insulators are based on the coupling of spin- and orbit interaction connected to its momentum. Specific ways to control the spin-polarization with light have been demonstrated: the energy momentum landscape of the Dirac cone provides spin-momentum locking of the charge current and its spin. The directionality of spin and momentum, as well as control with light has been demonstrated. Here we demonstrate a coherent femtosecond control of spin-polarization for states in the valence band at around the Dirac cone.Comment: 14 pages, 4 figure

Environmental monitoring programme in the cell therapy facility of a research centre: preliminary investigation

Introduction. Recent discoveries in cell therapy research present new opportunities for cellular products to be used to treat severe, and as yet incurable, diseases. It is therefore essential to implement a quality control programme in order to ensure that safe cells and tissues are provided. Methods. In a preliminary phase of the setting up of a the cell factory, monitoring was carried out monthly over a 6-month period in one out of three cell therapy laboratories and filter rooms in order to evaluate the microbial contamination of air and surfaces and the presence of airborne particulates. Results. The mean total bacterial and fungal loads measured in the air in the centre of the filter room were 20.7 ± 28.9 colonyforming units (cfu)/m3 and 9.2 ± 15.4 cfu/m3, respectively, and 5.2 ± 4.1 cfu/m3 and 6.8 ± 13.4 cfu/m3, respectively, in the laboratory. The mean fungal load values recorded on the surfaces sampled in the laboratory were in 6 out of 18 cases higher than the reference values (5 cfu/plate). As to the results of particulate monitoring, with regard to the 0.5 ?m particles, about 83% of the samples revealed values below the limit of 350.000 particles per cubic metre. Conclusions. In this set-up phase, monitoring was able to pick out structural and organisational flaws acceptable in a laboratory compliant with Good Manufacturing Practices class C (Annex 1), but not in a class B facility. Thanks to this preliminary monitoring phase, and by correcting these flaws, the clean room facility could achieve compliance to class B

Multiconfigurational nature of 5f orbitals in uranium and plutonium intermetallics

Uranium and plutonium's 5f electrons are tenuously poised between strongly bonding with ligand spd-states and residing close to the nucleus. The unusual properties of these elements and their compounds (eg. the six different allotropes of elemental plutonium) are widely believed to depend on the related attributes of f-orbital occupancy and delocalization, for which a quantitative measure is lacking. By employing resonant x-ray emission spectroscopy (RXES) and x-ray absorption near-edge structure (XANES) spectroscopy and making comparisons to specific heat measurements, we demonstrate the presence of multiconfigurational f-orbital states in the actinide elements U and Pu, and in a wide range of uranium and plutonium intermetallic compounds. These results provide a robust experimental basis for a new framework for understanding the strongly-correlated behavior of actinide materials.Comment: 30 pages, concatenated article and supporting information, 10 figure

Evidence for suppressed metallicity on the surface of La2-xSrxCuO4 and Nd2-xCexCuO4

Hard X-ray Photoemission spectroscopy (PES) of copper core electronic states, with a probing depth of $\sim$60 \AA, is used to show that the Zhang-Rice singlet feature is present in La$_2$CuO$_4$ but is absent in Nd$_2$CuO$_4$. Hole- and electron doping in La$_{2-x}$Sr$_x$CuO$_4$ (LSCO) and Nd$_{2-x}$Ce$_x$CuO$_4$ (NCCO) result in new well-screened features which are missing in soft X-ray PES. Impurity Anderson model calculations establish metallic screening as its origin, which is strongly suppressed within 15 $\text{\AA}$ of the surface. Complemented with X-ray absorption spectroscopy, the small chemical-potential shift in core levels ($\sim0.2$ eV) are shown to be consistent with modifications of valence and conduction band states spanning the band gap ($\sim1$ eV) upon hole- and electron-doping in LSCO and NCCO.Comment: 4 pages, 4 figure