Almost disjoint families and “never” cardinal invariants

summary:We define two cardinal invariants of the continuum which arise naturally from combinatorially and topologically appealing properties of almost disjoint families of sets of the natural numbers. These are the never soft and never countably paracompact numbers. We show that these cardinals must both be equal to $\omega_1$ under the effective weak diamond principle $\diamondsuit (\omega,\omega,<)$, answering questions of da Silva S.G., On the presence of countable paracompactness, normality and property $(a)$ in spaces from almost disjoint families, Questions Answers Gen. Topology 25(2007), no. 1, 1--18, and give some information about the strength of this principle

Preparation and characterization of bis-[1,3,5]triazinyl diazenes and their utilization as flame retardants in polypropylene films

A series of bis-[1,3,5]triazinyl diazenes and two metal complexes thereof were synthesized and tested as new flame retardants in polypropylene films. It was observed that electron withdrawing triazinyl ring substituents (i.e. Cl and phenyl moieties) improved the thermal stability of diazene compounds, whereas electron donating groups (i.e. methoxy, dimethylamino and ethylthio moieties) had a destabilizing effect. TGA, DTA/DSC, NMR and ATR-FTIR were used for the characterization. Quantum mechanical modeling (Gaussian 09) was also utilized to facilitate the interpretation of the NMR data. Bis-(4,6-dichloro-[1,3,5]triazin-2-yl)-diazene 1 and bis-(4,6-dimethoxy-[1,3,5]triazin-2-yl)-diazene 2 were found to be effective flame retardants in polypropylene films and DIN4102-1 B2 classification was reached already at a loading of 0.5 wt%. Interestingly, the copper complex of 2 showed even higher fire retardant activity than its precursor 2, whereas the corresponding zinc complex exhibited lower flame retardant efficacy than its precursor

Acoustic full-waveform inversion in an elastic world

Full-waveform inversion (FWI) is a technique used to obtain high-quality velocity models of the subsurface. Despite the elastic nature of the earth, the anisotropic acoustic wave equation is typically used to model wave propagation in FWI. In part, this simplification is essential for being efficient when inverting large 3D data sets, but it has the adverse effect of reducing the accuracy and resolution of the recovered P-wave velocity models, as well as a loss in potential to constrain other physical properties, such as the S-wave velocity given that amplitude information in the observed data set is not fully used. Here, we first apply conventional acoustic FWI to acoustic and elastic data generated using the same velocity model to investigate the effect of neglecting the elastic component in field data and we find that it leads to a loss in resolution and accuracy in the recovered velocity model. Then, we develop a method to mitigate elastic effects in acoustic FWI using matching filters that transform elastic data into acoustic data and find that it is applicable to marine and land data sets. Tests show that our approach is successful: The imprint of elastic effects on the recovered P-wave models is mitigated, leading to better-resolved models than those obtained after conventional acoustic FWI. Our method requires a guess of VP/VS and is marginally more computationally demanding than acoustic FWI, but much less so than elastic FWI. Read More: https://library.seg.org/doi/10.1190/geo2017-0063.

Addressing viscous effects in acoustic full-waveform inversion

In conventional full-waveform inversion (FWI), viscous effects are typically neglected, and this is likely to adversely affect the recovery of P-wave velocity. We have developed a strategy to mitigate viscous effects based on the use of matching filters with the aim of improving the performance of acoustic FWI. The approach requires an approximate estimate of the intrinsic attenuation model, and it is one to three times more expensive than conventional acoustic FWI. First, we perform 2D synthetic tests to study the impact of viscoacoustic effects on the recorded wavefield and analyze how that affects the recovered velocity models after acoustic FWI. Then, we apply the current method on the generated data and determine that it mitigates viscous effects successfully even in the presence of noise. We find that having an approximate estimate for intrinsic attenuation, even when these effects are strong, leads to improvements in resolution and a more accurate recovery of the P-wave velocity. Then, we implement and develop our method on a 2D field data set using Gabor transforms to obtain an approximate intrinsic attenuation model and inversion frequencies of up to 24 Hz. The analysis of the results indicates that there is an improvement in terms of resolution and continuity of the layers on the recovered P-wave velocity model, leading to an improved flattening of gathers and a closer match of the inverted velocity model with the migrated seismic data

Understanding Charles Bonnet syndrome: mechanisms and intervention

Ph. D. Thesis.Background: Charles Bonnet Syndrome (CBS) is defined by the occurrence of vivid, recurring visual hallucinations (VH) secondary to visual impairment in the absence of psychiatric illness or cognitive impairment. Previous research has proposed that deafferentation, due to loss of sensory input from the eyes, leads to spontaneous hyperexcitability in the visual cortex resulting in VH. Approximately one-third of people with CBS report distress and disruption to daily functioning as a consequence of VH, however there are currently no effective treatments and a lack of research into the aetiology of VH has hindered their development. Aims: 1) To investigate the role of visual cortical activity in the production of VH in CBS, compared to non-hallucinating controls, to better understand why VH occur in some patients but not others. 2) To investigate whether inhibitory non-invasive transcranial direct current stimulation (tDCS) could be used to remediate VH by reducing cortical excitability in CBS. Methods: Study 1: A comparison study consisting of people with CBS (n=19) and nonhallucinating sight-matched controls (n=18) was performed utilising transcranial magnetic stimulation, functional magnetic resonance imaging, and magnetic resonance spectroscopy to compare differences in visual cortical activity between groups. Study 2: Informed by a pilot study in continuous CBS hallucinators, sixteen members of the CBS group received 4- consecutive days of active and sham inhibitory tDCS over the primary visual cortex, comparing visual cortical activity and VH ratings before and after stimulation between active and sham weeks. Results: Study 1: Comparable visual cortical excitability was observed in both groups, although greater excitability was associated with more severe VH in the CBS group. Functional activation of the visual cortex was observed to be lower in the CBS group than controls during an eye movement task, with greater functional activation associated with lower visual cortical excitability. Study 2: Active cathodal tDCS of the primary visual cortex resulted in a significant decrease to VH frequency and intrusiveness compared to sham stimulation. No significant changes to cortical activity were observed following stimulation. Conclusions: This thesis constitutes the largest neurophysiological comparison and treatment study performed in CBS to date. These data support the role of changes to visual cortical activity in the production of VH following sight loss, providing a basis for further study. Furthermore, tDCS was observed to present a potential effective new treatment option for CBS, however further study is needed to understand underlying mechanisms.The Macular Society, Esme’s Umbrella, Fight for Sight, the National Eye Research Centre, and the Thomas Pocklington Trus

Differences in disease phenotype and severity in SLE across age groups

OBJECTIVES: Significant differences have been reported in disease phenotype and severity of systemic lupus erythematosus (SLE) presenting in different age groups. Most indicate a more severe phenotype in juvenile-onset SLE (JSLE). There have been limited studies in older patients and no large studies looking at SLE across all age groups. METHODS: We assessed the effect of age of onset of SLE on the clinical phenotype by analysing data from two large UK cohorts (the UK JSLE Cohort and the UCLH SLE cohort). RESULTS: A total of 924 individuals were compared (413 JSLE, 511 adult-onset SLE). A female preponderance was present, but less pronounced at either end of the age spectrum. Arthritis was more common with advancing age (93% vs 72%, p < 0.001), whereas renal disease (44% vs 33%, p = 0.001), alopecia (47% vs 23%, p < 0.001) and aphthous ulcerations (39% vs 26%, p = 0.001) were more common in the young. Neuropsychiatric lupus was less common in mature-onset SLE (p < 0.01). JSLE was associated more commonly with thrombocytopenia (21% vs 15%, p = 0.01), haemolytic anaemia (20% vs 3%, p < 0.001), high anti-dsDNA (71% vs 63%, p = 0.009), Sm (22% vs 16%, p = 0.02) and RNP (36% vs 29%, p < 0.04) auto-antibodies. Leucopenia increased with advancing age (p < 0.001). Mortality has been declining over recent decades. However, death rates were substantially higher than the general population. The standardized mortality ratio was 18.3 in JSLE and 3.1 in adult-onset SLE. CONCLUSION: These data from the largest-ever direct comparison of JSLE with adult-onset SLE suggest an aggressive phenotype of disease with a worse outcome in patients with JSLE and emphasizes the importance of careful follow-up in this population

Perfil dos indivíduos expostos sexualmente atendidos em um serviço de atenção especializada em DST/AIDS

Objective: The aim of the study was to identify the profile of the individuals searching for care in a Specialized Care Service (SCS) in HIV/AIDS for guidance, prevention and prophylaxis for HIV after sexual exposure.Methods: Quantitative, descriptive study, based on secondary data from 312 service reports from December 2010 to December 2014 in an SCS in Porto Alegre/Brazil. The selected data were: age; sex; exposure routes; positive / negative cases in the first test; return for follow-up and antiretrovirals used in prophylaxis.Results: Male gender predominated (73.7%), the age group with the highest incidence was between 20 and 39 years old (75.1%). The most chosen route for sexual practice was the vaginal one with 52.6%. In 63.3% of cases, patients were unaware of their partners’ serology and 35.7% knew their partner had the HIV virus, but did not use a condom. Even if exposed to partners with unknown or known HIV serology, 61.6% did not return to SCS. The two most prescribed antiretrovirals were those recommended by the Ministry of Health at the time.Conclusion: It is suggested to implement measures and campaigns to assist in the prevention of AIDS and, also, reinforce the importance of carrying out all stages of monitoring after sexual exposure.Objetivo: El objetivo del estudio fue identificar el perfil de las personas que buscaron atención en un Servicio de Atención Especializada (SAE) en ETS/SIDA para orientación, prevención y profilaxis del VIH después de la exposición sexual.Método: Estudio cuantitativo, descriptivo, basado en datos secundarios de 312 informes de diciembre de 2010 a diciembre de 2014 en un SAE de Porto Alegre/Brasil. Los datos seleccionados fueron: edad; sexo; rutas de exposición; casos positivos/negativos en la primera prueba; regreso para seguimiento de antirretrovirales utilizados em las profilaxis.Resultado: Predominó el género masculino (73.7%), el grupo de edad con mayor incidencia fue entre 20 y 39 años (75.1%). La ruta más elegida para la práctica sexual fue la vaginal 52.6%. En el 63.3% de los casos, los pacientes desconocían la serología de sus parejas y el 35.7% sabían que su pareja era VIH, pero no usaban condones. A pesar de exponerse a parejas con serología del VIH desconocida o conocida, el 61,6% no regresó a SAE. Los dos antirretrovirales más recetados fueron los recomendados por el Ministerio de Salud en ese momento.Conclusión: Se sugiere implementar medidas y campañas que ayuden en la prevención del SIDA y, además, refuercen la importancia de llevar a cabo todas las etapas del monitoreo después de la exposición sexual.Objetivo: O objetivo do estudo foi identificar o perfil dos indivíduos que procuraram por atendimento em um Serviço de Atenção Especializada (SAE) em DST/AIDS para orientação, prevenção e profilaxia para HIV após exposição sexual.Método: Estudo quantitativo, descritivo, baseado em dados secundários de 312 boletins de atendimento do período de dezembro de 2010 a dezembro de 2014 em um SAE de Porto Alegre/Brasil. Os dados selecionados foram: faixa etária dos indivíduos; sexo; vias de exposição; casos positivos/negativos na primeira testagem; retorno para acompanhamento e antirretrovirais utilizados nas profilaxias. Resultados: Predominou o sexo masculino (73,7%), a faixa etária de maior incidência foi entre 20 a 39 anos (75,1%). A via de maior escolha para prática sexual foi a vaginal 52,6%. Em 63,3% dos casos os pacientes desconheciam a sorologia dos parceiros e 35,7% sabiam que seu parceiro era HIV, porém não fizeram o uso do preservativo. Mesmo se expondo com parceiros de sorologia desconhecida ou sabidamente HIV, 61,6% não retornaram ao SAE. Os dois antirretrovirais mais prescritos foram os recomendados pelo Ministério da Saúde na época.Conclusões: Sugere-se a implementação de medidas e campanhas que auxiliem na prevenção da AIDS e, também, reforcem a importância na realização de todas as etapas do acompanhamento após a exposição sexual