Respiratory-gated (4D) contrast-enhanced FDG PET-CT for radiotherapy planning of lower oesophageal carcinoma: Feasibility and impact on planning target volume

Background: To assess the feasibility and potential impact on target delineation of respiratory-gated (4D) contrast-enhanced 18 Fluorine fluorodeoxyglucose (FDG) positron emission tomography - computed tomography (PET-CT), in the treatment planning position, for a prospective cohort of patients with lower third oesophageal cancer. Methods: Fifteen patients were recruited into the study. Imaging included 4D PET-CT, 3D PET-CT, endoscopic ultrasound and planning 4D CT. Target volume delineation was performed on 4D CT, 4D CT with co-registered 3D PET and 4D PET-CT. Planning target volumes (PTV) generated with 4D CT (PTV 4DCT), 4D CT co-registered with 3D PET-CT (PTV 3DPET4DCT) and 4D PET-CT (PTV 4DPETCT ) were compared with multiple positional metrics. Results: Mean PTV 4DCT , PTV 3DPET4DCT and PTV 4DPETCT were 582.4 ± 275.1 cm 3 , 472.5 ± 193.1 cm 3 and 480.6 ± 236.9 cm 3 respectively (no significant difference). Median DICE similarity coefficients comparing PTV 4DCT with PTV 3DPET4DCT, PTV 4DCT with PTV 4DPETCT and PTV 3DPET4DCT with PTV 4DPETCT were 0.85 (range 0.65-0.9), 0.85 (range 0.69-0.9) and 0.88 (range 0.79-0.9) respectively. The median sensitivity index for overlap comparing PTV 4DCT with PTV 3DPET4DCT, PTV 4DCT with PTV 4DPETCT and PTV 3DPET4DCT with PTV 4DPETCT were 0.78 (range 0.65-0.9), 0.79 (range 0.65-0.9) and 0.89 (range 0.68-0.94) respectively. Conclusions: Planning 4D PET-CT is feasible with careful patient selection. PTV generated using 4D CT, 3D PET-CT and 4D PET-CT were of similar volume, however, overlap analysis demonstrated that approximately 20% of PTV 3DPETCT and PTV 4DPETCT are not included in PTV 4DCT , leading to under-coverage of target volume and a potential geometric miss. Additionally, differences between PTV 3DPET4DCT and PTV 4DPETCT suggest a potential benefit for 4D PET-CT. Trial registration: ClinicalTrials.gov Identifier - NCT02285660(Registered 21/10/2014)

Effect of early and current Helicobacter pylori infection on the risk of anaemia in 6.5-year-old Ethiopian children

Background: Epidemiological and clinical studies in high income countries have suggested that Helicobacter pylori (H. pylori) may cause anaemia, but evidence is lacking from low income countries.We examined associations between H. pylori infection in early childhood and anaemia at the age of 6.5 years in an Ethiopian birth cohort. Methods: In 2011/12, 856 children (85.1 % of the 1006 original singletons in a population-based birth cohort) were followed up at age six and half. An interviewer-led questionnaire administered to mothers provided information on demographic and lifestyle variables. Haemoglobin level and red cell indices were examined using an automated haematological analyzer (Cell Dyn 1800, Abbott, USA), and stool samples analyzed for H. pylori antigen. The independent effects of H. pylori infection (measured at age 3.5 and 6.5 years) on anaemia, haemoglobin level, and red cell indices (measured at age 6.5 years) were determined using multiple logistic and linear regression. Results: The prevalence of anemia was 34.8 % (257/739), and the mean (SD) haemoglobin concentration was 11.8 (1.1) gm/dl. Current H. pylori infection at age 6.5 years was positively, though not significantly related to prevalence of anaemia (adjusted OR, 95 % CI, 1.15; 0.69, 1.93, p = 0.59). Any H. pylori infection up to age 6.5 years was significantly associated with an increased risk of anaemia at age 6.5 (adjusted OR, 95 % CI, 1.68; 1.22, 2.32, p = 0.01). A significant reduction in haemoglobin concentration and red cell indices was also observed among children who had any H. pylori infection up to age 6.5 (Hb adjusted β = −0.19, 95 % CI, −0.35 to −0.03, p = 0.01; MCV adjusted β = −2.22, 95 % CI, −3.43 to −1.01, p = 0.01; MCH adjusted β = −0.63, 95 % CI, −1.15 to - 0.12, p = 0.01; and MCHC adjusted β = −0.67, 95 % CI, −1.21 to −0.14, p = 0.01), respectively. Conclusion: This study provides further evidence from a low income country that any H. pylori infection up to age 6.5 is associated with higher prevalence of anaemia, and reduction of haemoglobin level and red cell indices at age 6.5

Search for gravitational-lensing signatures in the full third observing run of the LIGO-Virgo network

Gravitational lensing by massive objects along the line of sight to the source causes distortions of gravitational wave-signals; such distortions may reveal information about fundamental physics, cosmology and astrophysics. In this work, we have extended the search for lensing signatures to all binary black hole events from the third observing run of the LIGO--Virgo network. We search for repeated signals from strong lensing by 1) performing targeted searches for subthreshold signals, 2) calculating the degree of overlap amongst the intrinsic parameters and sky location of pairs of signals, 3) comparing the similarities of the spectrograms amongst pairs of signals, and 4) performing dual-signal Bayesian analysis that takes into account selection effects and astrophysical knowledge. We also search for distortions to the gravitational waveform caused by 1) frequency-independent phase shifts in strongly lensed images, and 2) frequency-dependent modulation of the amplitude and phase due to point masses. None of these searches yields significant evidence for lensing. Finally, we use the non-detection of gravitational-wave lensing to constrain the lensing rate based on the latest merger-rate estimates and the fraction of dark matter composed of compact objects

Why Are Plant Deaths Countercyclical: Reallocation Timing or Fragility?

Because plant deaths destroy specific capital with large local economic impacts and potentially important macroeconmic effects, understanding the causes of deaths and, in particular, why they are concentrated in cyclical downturns, is important. The reallocationtiming hypothesis posits that plants suffering adverse permanent demand/productivity shocks delay shutdowns until cyclical downturns when plant capacity is less valuable, while the fragility hypothesis posits that shutdowns occur in downturns because the option value of maintaining the plant through low profitability periods is too small. I show that the effect that a plant’s specific capital has on the timing of plant deaths differs across these two hypotheses and then use this insight to test the hypotheses’ relative importance. I find that fragility is the dominant cause of the countercyclical behavior of plant deaths. This suggests that the endogenous destruction of capital is likely an important amplification and propagation mechanism for cyclical shocks and that stabilization policies have the benefit of reduced capital destruction.Plant deaths, business cycle

The cyclical behavior of short-term and long-term job flows

Using a band pass filter, this paper estimates plant-level job flows at different frequencies and examines the characteristics of the high frequency (transitory) and low frequency (permanent) component flows. Because high frequency employment movements, which likely result in changes in the utilization of plant assets, and low frequency movements, which likely coincide with the restructuring of plant assets, result in different costs to the economy, understanding their separate behavior is important. High frequency plant-level employment fluctuations account for the majority of cyclical movements in aggregate manufacturing employment, but the temporal separation between job destruction and job creation is more pronounced for low frequency job flows, suggesting that permanent job flows reflect a more protracted employment adjustment process. To facilitate the evaluation of job flow models, many of which describe either transitory or permanent job flows, time series of job flows at different frequencies are presented in the appendix.Employment (Economic theory) ; Labor market

Is reallocation related to the cycle? A look at permanent and temporary job flows

How much of aggregate employment fluctuations is due to plants destroying and then recreating the same jobs over the cycle and how much is due to some plants permanently destroying jobs in a recession and other plants permanently creating jobs in an expansion? This paper decomposes plant level job flows into permanent and temporary components to answer this question, and finds that the permanent reallocation of jobs across plants accounts for approximately 30 percent of the cyclical fluctuations in aggregate employment.Employment (Economic theory) ; Business cycles