Most of the studies that established the sterile womb paradigm are based on microbial culture, which fails to detect viable but non-cultivable microbes. DNA-based PCR and sequencing methods overcome this limitation, and it is possible that bacteria detectable by these methods in the fetal-placental environment and meconium do represent viable, metabolically active organisms that are non-cultivable. However, one must also consider that these molecular methods have inherent limitations. First, even if bacterial DNA is detectable, the organisms could be dead. This consideration is especially relevant for the placenta, as an important role for this tissue is the removal of microbes and their components that might be present in the blood [76]. Additionally, for research to successfully challenge the sterile womb paradigm, a demonstration of microbial viability is essential, as sites can be sterile even while containing bacterial DNA. Very few groups have demonstrated viable microorganisms in the fetal environment despite these studies employing culture methods that readily grow bacteria from other parts of the body [77,78,79,80,81,82,83]. In the case of Satokari and colleagues [84], the authors could not culture bacteria detected by molecular methods (Bifidobacterium and Lactobacillus) even though these are readily cultivable organisms. Although the authors attribute this result to freezing the samples prior to processing, they also ponder the possibility that only bacterial products including DNA, rather than living bacteria, are present in the placenta. In fact, freezing samples before processing has been performed in many culture-based studies of microbiomes, and although it reduces bacterial counts, it normally does not prevent cultivation. In the case of Collado and colleagues [10], identification of bacteria cultured from the placenta and amniotic fluid of newborns delivered by C-section was limited to multiple isolates of Propionibacterium and Staphylococcus species, and one isolate each of Streptomyces and Lachnospiraceae. Propionibacterium and Staphylococcus species are ubiquitous normal skin commensals and could therefore originate from contamination (see below). Importantly, the authors reported that Enterobacter and Escherichia/Shigella were the most abundant genera detected in placenta and amniotic fluid samples. However, they were not able to recover these organisms by culture methods despite the relative ease in cultivating these bacterial groups. Taken together, these findings and other current data do not support the existence of live bacteria in the placenta.
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At a December 7, 2010, press briefing,[104][105][106] Google announced the ChromeOS Pilot Program, a pilot experiment and the first Chromebook, the Cr-48 Chrome Notebook, a prototype, to test the ChromeOS operating system and modified hardware for it. The device had a minimal design and was all black, completely unbranded although it was made by Inventec,[107] and had a rubberized coating. The device was named after Chromium-48, an unstable isotope of the metallic element Chromium (chemical symbol Cr),[108] and the participants were named Cr-48 Test Pilots. Google distributed about 60,000 Cr-48 Chrome Notebooks between December 2010 and March 2011[109][110] for free to participants and in return asked for feedback such as suggestions and bug reports. The Cr-48 was intended for testing only, not retail sales.[111][112][113]
Melting Layer is a computer algorithm output that determines the atmospheric melting point for frozen precipitation. This product provides information about the state (frozen, melting, or fully liquid) of precipitation at different altitudes in a particular area. This product is generated for each elevation angle that the radar scans and can be particularly useful for tracking icing conditions above the surface. It may have problems when surface temperatures are below freezing, in mountainous locations, or when data needed for the algorithm is limited. When radar echoes are insufficient for the algorithm to work properly, it will default to the manually entered or model generated freezing level data. 2ff7e9595c
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