CMB-S4: Forecasting Constraints on Primordial Gravitational Waves

CMB-S4---the next-generation ground-based cosmic microwave background (CMB) experiment---is set to significantly advance the sensitivity of CMB measurements and enhance our understanding of the origin and evolution of the Universe, from the highest energies at the dawn of time through the growth of structure to the present day. Among the science cases pursued with CMB-S4, the quest for detecting primordial gravitational waves is a central driver of the experimental design. This work details the development of a forecasting framework that includes a power-spectrum-based semi-analytic projection tool, targeted explicitly towards optimizing constraints on the tensor-to-scalar ratio, $r$, in the presence of Galactic foregrounds and gravitational lensing of the CMB. This framework is unique in its direct use of information from the achieved performance of current Stage 2--3 CMB experiments to robustly forecast the science reach of upcoming CMB-polarization endeavors. The methodology allows for rapid iteration over experimental configurations and offers a flexible way to optimize the design of future experiments given a desired scientific goal. To form a closed-loop process, we couple this semi-analytic tool with map-based validation studies, which allow for the injection of additional complexity and verification of our forecasts with several independent analysis methods. We document multiple rounds of forecasts for CMB-S4 using this process and the resulting establishment of the current reference design of the primordial gravitational-wave component of the Stage-4 experiment, optimized to achieve our science goals of detecting primordial gravitational waves for $r > 0.003$ at greater than $5\sigma$, or, in the absence of a detection, of reaching an upper limit of $r < 0.001$ at $95\%$ CL.Comment: 24 pages, 8 figures, 9 tables, submitted to ApJ. arXiv admin note: text overlap with arXiv:1907.0447

CMB-S4: Forecasting Constraints on Primordial Gravitational Waves

Abstract: CMB-S4—the next-generation ground-based cosmic microwave background (CMB) experiment—is set to significantly advance the sensitivity of CMB measurements and enhance our understanding of the origin and evolution of the universe. Among the science cases pursued with CMB-S4, the quest for detecting primordial gravitational waves is a central driver of the experimental design. This work details the development of a forecasting framework that includes a power-spectrum-based semianalytic projection tool, targeted explicitly toward optimizing constraints on the tensor-to-scalar ratio, r, in the presence of Galactic foregrounds and gravitational lensing of the CMB. This framework is unique in its direct use of information from the achieved performance of current Stage 2–3 CMB experiments to robustly forecast the science reach of upcoming CMB-polarization endeavors. The methodology allows for rapid iteration over experimental configurations and offers a flexible way to optimize the design of future experiments, given a desired scientific goal. To form a closed-loop process, we couple this semianalytic tool with map-based validation studies, which allow for the injection of additional complexity and verification of our forecasts with several independent analysis methods. We document multiple rounds of forecasts for CMB-S4 using this process and the resulting establishment of the current reference design of the primordial gravitational-wave component of the Stage-4 experiment, optimized to achieve our science goals of detecting primordial gravitational waves for r > 0.003 at greater than 5σ, or in the absence of a detection, of reaching an upper limit of r < 0.001 at 95% CL

Focal glomerular sclerosis

In 1957 Rich [1] presented observations in 20 children with the nephrotic syndrome who died between several months and five years after the onset of edema. One-half of these children died from infection. He described a progressive sclerosis of glomeruli starting in the juxtamedullary region of the kidney and suggested that this was the usual way in which lipoid nephrosis progressed. A few years later, studies of renal biopsy specimens from patients with the idiopathic nephrotic syndrome revealed a particular group that was characterized by the presence of focal sclerosing glomerular lesions as distinct from others with minimal or diffuse glomerular lesions [2–4]. It is only in recent years that a clear correlation has been established between these focal lesions and a specific clinical course. A high incidence of microscopic hematuria, corticosteroid resistance and developing renal insufficiency in nephrotic patients with this finding has now been reported by most authors [5–17].Since the lesions under discussion are characterized by focal involvement of glomeruli and by the sclerotic changes which take place in affected glomeruli, the terms focal glomerular sclerosis (FGS) or focal sclerosing glomerulonephropathy [17] seem appropriate. Other names such as focal sclerosing glomerulonephritis [4, 16] or focal glomerulosclerosis [11, 15, 20] have been proposed. In our opinion the word ‘glomerulonephritis’ should be avoided because of the confusion it may introduce in reference to focal and segmental glomerulonephritis [9]. The term ‘focal gbmerulosclerosis’ is also confusing since, for decades, the word ‘glomerulosclerosis’ has been used for the small sclerotic glomeruli often found in infant kidneys [18, 19].The frequent histologic finding of FGS in nephrotic patients whose clinical presentation at onset could not be distinguished from that of ‘nephrosis,’ or who might have exhibited minimal glomerular lesions on a previous biopsy specimen [3, 5, 8, 13, 14, 16, 17], raises an important question as to the relationship between ‘minimal lesion nephrotic syndrome’ (M LNS) and this ‘disease’ (FGS). A recent report of the possible recurrence of the nephrotic syndrome and the focal lesion in transplanted kidneys suggests that a humoral factor may be operative which antedates the glomerular structural changes. Accurate diagnosis of FGS in nephrotic patients may therefore be of considerable practical importance