Linearized inverse scattering based on seismic Reverse Time Migration

In this paper we study the linearized inverse problem associated with imaging of reflection seismic data. We introduce an inverse scattering transform derived from reverse-time migration (RTM). In the process, the explicit evaluation of the so-called normal operator is avoided, while other differential and pseudodifferential operator factors are introduced. We prove that, under certain conditions, the transform yields a partial inverse, and support this with numerical simulations. In addition, we explain the recently discussed 'low-frequency artifacts' in RTM, which are naturally removed by the new method

A short note on the nested-sweep polarized traces method for the 2D Helmholtz equation

We present a variant of the solver in Zepeda-N\'u\~nez and Demanet (2014), for the 2D high-frequency Helmholtz equation in heterogeneous acoustic media. By changing the domain decomposition from a layered to a grid-like partition, this variant yields improved asymptotic online and offline runtimes and a lower memory footprint. The solver has online parallel complexity that scales \emph{sub linearly} as $\mathcal{O} \left( \frac{N}{P} \right)$, where $N$ is the number of volume unknowns, and $P$ is the number of processors, provided that $P = \mathcal{O}(N^{1/5})$. The variant in Zepeda-N\'u\~nez and Demanet (2014) only afforded $P = \mathcal{O}(N^{1/8})$. Algorithmic scalability is a prime requirement for wave simulation in regimes of interest for geophysical imaging.Comment: 5 pages, 5 figure

Later achievement of infant motor milestones is related to lower levels of physical activity during childhood::the GECKO Drenthe cohort

BACKGROUND: The aim of this study is to investigate whether age of infant motor milestone achievement is related to levels of physical activity (PA), weight status and blood pressure at age 4-7 years of age. METHODS: In the Dutch GECKO (Groningen Expert Center of Kids with Obesity) Drenthe cohort, the age of achieving the motor milestone 'walking without support' was reported by parents. Weight status and blood pressure were assessed by trained health nurses and PA was measured using the Actigraph GT3X between age 4 and 7 years. RESULTS: Adjusted for children's age, sex and the mother's education level, infants who achieved walking without support at a later age, spent more time in sedentary behaviour during childhood and less time in moderate-to-vigorous PA. Later motor milestones achievement was not related to higher BMI Z-score, waist circumference Z-score, diastolic or systolic blood pressure. CONCLUSION: The results of this study indicate that a later age of achieving motor milestone within the normal range have a weak relation to lower PA levels at later age. It is not likely that this will have consequences for weight status or blood pressure at 4-7 years of age

The metabolic syndrome in black hypertensive women waist circumference more strongly related than body Mass index

Objective. To examine the association between measures of obesity and features of the metabolic  syndrome in treated black female hypertensive subjects.Design. Cross-sectional study.Setting. An urban primary health care centre in Mamelodi, Pretoria.Subjects. Women with hypertension and without known diabetes mellitus or secondary causes of  hypertension. In total124 women participated, with a mean age of 56.9 years (standard deviation (SO) 11.0) and mean body mass index (BMI) of 34.1 kg/m' (SO 8.1).Main outcome measures. Blood pressure, glucose, insulin and lipid levels.Results. Waist circumference and waist-hip ratio were more strongly associated with insulin, uric acid,  glucose and triglycerides than was BMI. Statistically significant associations were found between waist circumference and low high-density lipoprotein HOL cholesterol (standardised regression coefficient --0.006, standard error of the mean (SEM) 0.002), log triglycerides (0.007, SEM 0.003), uric acid (0.002, SEM 0.001) and log insulin (0.012, SEM 0.003). BMI was only significantly associated with uric acid  (0.002, SEM 0.002) and log insulin (0.009, SEM 0.004).Conclusion. In a group of black hypertensive women measures of central obesity were more strongly  associated with components of the metabolic syndrome than BMI

Assessing peripheral arteries in South African black women with type 2 diabetes mellitus

Objectives. To determine the value of ankle and toe blood pressure indices and pedal pulse palpation in the assessment of peripheral arterial disease in subjects with type 2 diabetes mellitus (DM).Design. Cross-sectional study.Subjects. A convenience sample of 85 female subjects with type 2 DM underwent a series of peripheral vascular assessments at the diabetes clinic of a community hospital.Outcome measures. Palpation of the pedal pulses, Doppler derived ankle brachial systolic blood pressure indices, photo plethysmographic-derived toe brachial systolic blood pressure indices and antero-posterior radiographs of both feet.Results. Mean values were 1.15 (standard deviation (SD): 0.17) and 0.76 (SD: 0.17) for ankle brachial index (ABI) and toe brachial index (T'Bl) respectively. The differences between the two indices increased from 0.36 (95% confidence interval (CI): 0.32 - 0.41) to 0.58 (95% CI: 0.46- 0.70) depending on whether ABI was less or greater than 1.3. The correlation coefficient for left versus right foot was 0.62 and 0.71 for ABI and TBI respectively. The relationship between ABI and TBI is non-linear with a cut point close to 1.3. Both ABI and TBI were significantly lower in subjects who had both pedal pulses absent on palpation.Conclusions. The relationship between ABI and TBI is linear, below an ABI of 1.3. but with a wide 95% prediction interval. If both pedal pulses are absent the ABI is significantly diminished compared with when both pulses are present, even though not necessarily below 0.9. 

Protease-Specific Biomarkers to Analyse Protease Inhibitors for Emphysema Associated with Alpha 1-Antitrypsin Deficiency. An Overview of Current Approaches.

As a known genetic cause of chronic obstructive pulmonary disease (COPD), alpha1-antitrypsin deficiency (AATD) can cause severe respiratory problems at a relatively young age. These problems are caused by decreased or absent levels of alpha1-antitrypsin (AAT), an antiprotease which is primarily functional in the respiratory system. If the levels of AAT fall below the protective threshold of 11 µM, the neutrophil-derived serine proteases neutrophil elastase (NE) and proteinase 3 (PR3), which are targets of AAT, are not sufficiently inhibited, resulting in excessive degradation of the lung parenchyma, increased inflammation, and increased susceptibility to infections. Because other therapies are still in the early phases of development, the only therapy currently available for AATD is AAT augmentation therapy. The controversy surrounding AAT augmentation therapy concerns its efficiency, as protection of lung function decline is not demonstrated, despite the treatment's proven significant effect on lung density change in the long term. In this review article, novel biomarkers of NE and PR3 activity and their use to assess the efficacy of AAT augmentation therapy are discussed. Furthermore, a series of seven synthetic NE and PR3 inhibitors that can be used to evaluate the specificity of the novel biomarkers, and with potential as new drugs, are discussed

Transposable elements promote the evolution of genome streamlining

Eukaryotes and prokaryotes have distinct genome architectures, withmarked differences in genome size, the ratio of coding/non-coding DNA,and the abundance of transposable elements (TEs). As TEs replicate inde-pendently of their hosts, the proliferation of TEs is thought to have drivengenome expansion in eukaryotes. However, prokaryotes also have TEs inintergenic spaces, so why do prokaryotes have small, streamlined genomes?Using anin silicomodel describing the genomes of single-celled asexualorganisms that coevolve with TEs, we show that TEs acquired from theenvironment by horizontal gene transfer can promote the evolution ofgenome streamlining. The process depends on local interactions and isunderpinned by rock–paper–scissors dynamics in which populations ofcells with streamlined genomes beat TEs, which beat non-streamlinedgenomes, which beat streamlined genomes, in continuous and repeatingcycles. Streamlining is maladaptive to individual cells, but improves lineageviability by hindering the proliferation of TEs. Streamlining does not evolvein sexually reproducing populations because recombination partially freesTEs from the deleterious effects they cause.This article is part of the theme issue‘The secret lives of microbial mobilegenetic elements’

The role of fitness in the association between fatness and cardiometabolic risk from childhood to adolescence

Background Fatness and fitness both influence cardiometabolic risk. Objective The purpose of this study was to investigate whether childhood fatness and increasing fatness from childhood to adolescence are associated with cardiometabolic risk during adolescence and how fitness affects this association. Subjects and methods Of 565 adolescents (283 boys and 282 girls) from the TRacking Adolescents Individual Life Survey (TRAILS) data on anthropometric parameters (age 11 and 16), metabolic parameters, and fitness (age 16) were available. Body mass index and skinfolds were used as measures for fatness. Increasing fatness was calculated by subtracting Z-scores for fatness at age 11 from Z-score fatness at age 16. Cardiometabolic risk was calculated as the average of the standardized means of mean arterial pressure, fasting serum triglycerides, high-density lipoprotein-cholesterol, glucose, and waist circumference. Insulin resistance was calculated by homeostasis model assessment-insulin resistance (HOMA-IR). Fitness was estimated as maximal oxygen consumption (VO2max) during a shuttle run test. Results Boys showed a higher clustered cardiometabolic risk when compared to girls (p < 0.01). Childhood fatness (age 11) and increasing fatness were independently associated with cardiometabolic risk during adolescence. In boys, high fitness was related to a reduced effect of increasing fatness on clustered cardiometabolic risk. Childhood fatness, increasing fatness, and fitness were independently associated with HOMA-IR. Moreover, in boys this association was dependent of fatness. Conclusions Childhood fatness and increasing fatness are associated with increased cardiometabolic risk and HOMA-IR during adolescence, but a good fitness attenuates this association especially in fat boys