Surface Phase Metastability during Langmuir Evaporation.

We have directly imaged the spontaneous formation of metastable surface phase domains on GaAs(001) during Langmuir evaporation. Eventually, these metastable phases transform to the thermodynamically stable parent phase, producing a dynamic phase coexistence with a temperature dependent, time-averaged coverage. Monte Carlo simulations are used to identify the key kinetic processes and investigate the interplay between phase metastability and evolving surface morphology. This is used to explain the measured temperature dependence of the time-averaged coverage.

Spin excitations in a single La2CuO4 layer.

Cuprates and other high-temperature superconductors consist of two-dimensional layers that are crucial to their properties. The dynamics of the quantum spins in these layers lie at the heart of the mystery of the cuprates. In bulk cuprates such as La(2)CuO(4), the presence of a weak coupling between the two-dimensional layers stabilizes a three-dimensional magnetic order up to high temperatures. In a truly two-dimensional system however, thermal spin fluctuations melt long-range order at any finite temperature. Here, we measure the spin response of isolated layers of La(2)CuO(4) that are only one-unit-cell-thick. We show that coherent magnetic excitations, magnons, known from the bulk order, persist even in a single layer of La(2)CuO(4), with no evidence for more complex correlations such as resonating valence bond correlations. These magnons are, therefore, well described by spin-wave theory (SWT). On the other hand, we also observe a high-energy magnetic continuum in the isotropic magnetic response that is not well described by two-magnon SWT, or indeed any existing theories.

Impact of the COVID-19 pandemic on tuberculosis management in Spain.

BACKGROUND: The impact of COVID-19 on the diagnosis and management of tuberculosis (TB) patients is unknown. METHODS: Participating centres completed a structured web-based survey regarding changes to TB patient management during the COVID-19 pandemic. The study also included data from participating centres on patients aged ≥18 diagnosed with TB in 2 periods: March 15 to June 30, 2020 and March 15 to June 30, 2019. Clinical variables and information about patient household contacts were retrospectively collected. RESULTS: A total of 7 (70%) TB units reported changes in their usual TB team operations. Across both periods of study, 169 patients were diagnosed with active TB (90 in 2019, 79 in 2020). Patients diagnosed in 2020 showed more frequent bilateral lesions in chest X-ray than patients diagnosed in 2019 (P = 0.004). There was a higher percentage of latent TB infection and active TB among children in households of patients diagnosed in 2020, compared with 2019 (P = 0.001). CONCLUSIONS: The COVID-19 pandemic has caused substantial changes in TB care. TB patients diagnosed during the COVID-19 pandemic showed more extended pulmonary forms. The increase in latent TB infection and active TB in children of patient households could reflect increased household transmission due to anti-COVID-19 measures.

Selected energy dark-field imaging using low energy electrons for optimal surface phase discrimination.

We propose a general strategy for surface phase discrimination by dark-field imaging using low energy electrons, which maximizes contrast using diffraction spots, at selected optimal energies. The method can be automated to produce composite phase maps in real space and study the dynamics of complex phase transformations in real-time. To illustrate the capabilities of the technique, surface phases are mapped in the vicinity of liquid Ga droplets on the technologically important GaAs (001) surface.

Effect of Co substitution on the magnetic and electron-transport properties of Mn2PtSn.

The structural, magnetic and electron-transport properties of Mn(2)Pt(1-x)Co(x)Sn(x = 0, 0.3, 0.5, 0.7, 1) ribbons prepared by arc-melting and melt-spinning were investigated. The rapidly quenched alloys with x = 0 and 0.3 were found to crystallize in the inverse tetragonal structure, but the structure transformed into inverse cubic as x increased to 0.5. At room temperature, the samples are ferro or ferrimagnetic, and the Curie temperature increases by 225 K from 370 K for Mn(2)PtSn (x = 0) to 595 K for Mn(2)CoSn (x = 1). The measured anisotropy constants for the inverse-tetragonal alloys are on the order of 1 Merg cm(-3) at room temperature. The ribbons are moderately conducting with the room temperature resistivities being between 0.4 and 8.4 mΩ cm. Interestingly, the thermal coefficient of resistivity transforms from positive to negative and the magnetoresistance transforms from negative to positive as the value of x reaches 0.5.

A comparison between septic bursitis caused by Staphylococcus aureus and those caused by other organisms.

Septic bursitis is an infection that usually involves olecranon and prepatellar bursae. Staphylococcus aureus is responsible for around 80% of cases. However, information regarding bursitis caused by non-Staphylococcus aureus microorganisms (NSAB) is scant. In this paper we describe the characteristics of NSAB and emphasise differences between these and Staphylococcus aureus bursitis (SAB). A retrospective study of all cases with septic bursitis seen between January 1991 and June 1998 at one university hospital was conducted. Only cases in which bursal fluid culture yielded growth of a microorganism were analysed. A literature review was conducted for completeness. Fifty-seven episodes of septic bursitis in 56 patients were studied: 47 of these were caused by Staphylococcus aureus and 11 by non-Staphylococcus aureus microorganisms. Forty-three SAB patients were male (91%). Mean age at diagnosis was 50 years (range 20-85 years). The presentation of bursitis had a seasonal trend, with a peak in the summer. Twenty-three patients (51%) had occupations involving frequent or sustained pressure on the bursae. Other risk factors were recent trauma in 11 (23%), alcoholism in six (13%), pre-existing bursal disease in five (11%), and chronic obstructive pulmonary disease in four (9%). There were 20 cases of olecranon bursitis (43%), 25 of prepatellar bursitis (53%) and two of first metatarsophalangeal bursitis. Characteristics of patients from the literature review were similar. Eight NSAB patients (73%) were male. Mean age at diagnosis was 46.9 (range 29-83 years). Two patients were plumbers and one a stonemason. Five (45%) had neither putative systemic nor local risk factors. There were five olecranon (45%), five prepatellar (45%), and one external malleolus bursitis. Infection by a mixed flora was common. Unlike SAB, the presentation of cases did not have a seasonal trend. The clinical spectrum of non-Staphylococcus aureus bursitis (NSAB) differs from that of Staphylococcus Aureus bursitis (SAB), and this should be considered in the initial diagnosis of septic bursitis.

Insights from the study of high-temperature interface superconductivity.

A brief overview is given of the studies of high-temperature interface superconductivity based on atomic-layer-by-layer molecular beam epitaxy (ALL-MBE). A number of difficult materials science and physics questions have been tackled, frequently at the expense of some technical tour de force, and sometimes even by introducing new techniques. ALL-MBE is especially suitable to address questions related to surface and interface physics. Using this technique, it has been demonstrated that high-temperature superconductivity can occur in a single copper oxide layer-the thinnest superconductor known. It has been shown that interface superconductivity in cuprates is a genuine electronic effect-it arises from charge transfer (electron depletion and accumulation) across the interface driven by the difference in chemical potentials rather than from cation diffusion and mixing. We have also understood the nature of the superconductor-insulator phase transition as a function of doping. However, a few important questions, such as the mechanism of interfacial enhancement of the critical temperature, are still outstanding.

Soluciones técnicas para la patela baja y artrofibrosis sobre prótesis total de rodilla / Technical solutions for patella baja and arthrofibrosis after total knee replacement

Objetivo. El tratamiento de la patela baja y la artrofibrosis tras una prótesis total de rodilla (PTR) continúa siendo un problema de difícil solución. Una predisposición individual, un tratamiento excesivamente agresivo de los tejidos y partes blandas o un programa de rehabilitación demasiado exigente han sido expuestos como posibles causas desencadenantes. Se han propuesto varias opciones técnicas: patelectomía, transposición proximal de la tuberosidad tibial (TTA), distalización del componente femoral, desbridamiento abierto o artroscópico de la fibrosis intraarticular. Material y método. Presentamos una serie de 5 pacientes con patela baja y artrofibrosis sobre una prótesis total de rodilla (PTR), que desarrollaron una retracción progresiva del tendón rotuliano, tratados mediante una artrólisis abierta, resección el tercio distal de la rótula para alargar dicho tendón y protetización de los dos tercios restantes de patela. Resultados. Tras la cirugía el dolor anterior de la rodilla ha mejorado en el 100% de los casos y los índices de Insall-Salvati, Blackburne y Caton están más próximos a la normalidad que antes de realizar nuestro procedimiento quirúrgico. El incremento promedio de movilidad fue de 48°. Las puntuaciones de la Sociedad Americana de Rodilla (KSS) se incrementaron en más del doble respecto a los valores preoperatorios, pasando desde 44 puntos promedio para la clínica hasta 78 tras la cirugía y para la función desde 39 puntos promedio hasta 73. Conclusiones. Esta técnica, descrita originalmente por los autores, debería ser tenida en cuenta como un recurso útil para el tratamiento de patelas bajas aisladas con artrofibrosis y en cirugías de revisión de aquellas artroplastias fracasadas por otras causas que tengan una patela baja añadida. Su principal ventaja, frente a otras alternativas quirúrgicas, es la sencillez y la falta de morbilidad

Purpose. Treatment of patella baja and arthrofibrosis after total knee replacement (TKR) remains a difficult problem to address. The individual's predisposition, an overly traumatic handling of soft tissues and an overdemanding rehabilitation program have all been suggested as potential causes. Several technical options have been put forward: patellectomy, anterior tibial translation (ATT), femoral component distalization, open pr arthroscopic debridement of the intraarticular fibrosis. Materials and methods. We present a series of 5 patients with patella baja and arthrofibrosis after total knee replacement (TKR) that developed a progressive retraction of the patellar tendon and were treated by means of open arthrolysis, resection of the distal third of patella to lengthen the said tendon and prosthetization of the remaining two-thirds of the patella. Results. After surgery, anterior knee pain improved in 100% of cases with the Insall-Salvati, Blackburne and Caton scores drawing closer to normality than in the preoperative period. Average increase in the range of motion was 48°. The US Knee Society ratings rose more than twofold with respect to their preoperative values, with the Knee Score going from an average 44 points to 78 points after surgery and the Function Score from an average 39 points to 73. Conclusions. This technique, described for the first time by the authors of this paper, should be taken into account as an useful resource for the treatment of isolated patella baja with arthrofibrosis and for the revision of artrhoplasties that failed because of some other season but have an associated patella baja. The main advantage of the proposed technique as compared with other surgical alternatives is its simplicity and low morbidity

Tratamiento en dos tiempos de la artroplastia total de rodilla infectada: estudio comparativo entre dos tipos de espaciadores / Two step surgical treatment of infected total knee replacement: comparative study of two different types of spacers

Introducción y objetivo. La infección tras la artroplastia total de rodilla, representa la peor complicación posible de este procedimiento quirúrgico, requiriendo la combinación de tratamientos complejos, junto con una prolongada hospitalización. El tratamiento debe ser multidisciplinario y sus objetivos son erradicar la infección y preservar la función de la extremidad. El objetivo del presente estudio es analizar nuestras guías y protocolos de diagnóstico y tratamiento y realizar un estudio retrospectivo comparando los resultados de dos formas diferentes de tratamiento de una artroplastia total de rodilla infectada. Material y método. El primer grupo de tratamiento lo componen los pacientes intervenidos mediante reimplantación en dos tiempos y dejando un espaciador monobloque entre cirugías sin permitir la movilidad. En el segundo grupo de pacientes se emplearon espaciadores articulados y se les permitió una movilidad controlada en el tiempo entre las cirugías. Se analizaron las diferencias en porcentaje de reimplantación, movilidad final y resultados clínicos y funcionales entre ambos grupos y se comparan los resultados entre diferentes tipos de prótesis. Resultados y conclusiones. Los espaciadores articulados en el tiempo entre cirugías y las prótesis constreñidas en la reimplantación se asociaron con mejores resultados

Introduction and purpose. Infection of total knee replacement (TKR) surgery is the worst complication of this procedure. It requires complex treatment and prolonged hospitalisation. The treatment must be carried out by a multidisciplinary team and its goal is to eradicate infection and preserve the function of the limb. The aim of this study is to analyse our diagnostic and treatment guides and protocols, and to carry out a retrospective study comparing the results of two different types of treatment of infection of total knee replacement surgery. Material and methods. The first group of patients had a two step knee replacement surgery with a monoblock spacer left in place between operations, but during this period no movement of the joint was allowed. The second group of patients had a two step knee replacement surgery with an articulated spacer left in place between operations, and during this period controlled movement of the joint was allowed. An analysis was carried out of the differences between the two groups in: percentages of re-implantation, final range of motion (ROM), clinical and functional outcomes, and results due to the use of different prosthesis. Outcomes and conclusions. Better outcomes were observed with the use of joint spacers in two step surgery and constrained prosthesis in re-implantation procedures