Optimization of image quality and accuracy of low iodine concentration quantification as function of kVp pairs for abdominal imaging using dual-source CT: A phantom study

PurposeTo determine the suitable kVp pair for optimal image quality of the virtual monochromatic images (VMIs) and iodine quantification accuracy at low concentration, using a third generation dual-source CT (DSCT).Materials and methodsMulti-energy CT phantoms with and without body rings were scanned with a DSCT using four kVp pairs (tube “A”/“B” voltage): 100/Sn150, 90/Sn150, 80/Sn150 and 70/Sn150 kVp. The reference mAs was adjusted to obtain a CTDI_vol close to 11 mGy. HU values accuracy (RMSD_HU), noise (SD) and contrast-to-noise ratio (CNR) of iodine inserts of 0.5, 1, 2 and 5 mg/mL concentrations were assessed on VMIs at 40/50/60/70 keV. Iodine quantification accuracy was assessed using the RMSD_iodine and iodine bias (IB_iodine).ResultsThe RMSD_HU decreased when the tube “A” voltage increased. The mean noise value increased significantly with tube “A” voltage (p < 0.001) but decreased between 80/Sn150 and 90/Sn150 kVp for the small phantom (1.1 ± 0.1%; p = 0.047). The CNR significantly decreased with tube “A” voltage (p < 0.001), except between 80/Sn150 and 90/Sn150 kVp for all inserts and between 90/Sn150 kVp and 100/Sn150 kVp for the 1.0 and 0.5 mg/mL inserts in the large phantom. In the small phantom, no significant difference was found between 80/Sn150 kVp and 90/Sn150 kVp for all inserts and between 80/Sn150, 90/Sn150 and 100/Sn150 kVp for the 1 and 0.5 mg/mL inserts. The RMSD_iodine and IB_iodine decreased as the tube “A” voltage of the kVp pair increased.ConclusionThe kVp pair of 70/Sn150 led to better image quality in VMIs and sufficient iodine accuracy.     

Floristic changes in vascular plants in the British Isles: geographical and temporal variation in botanical activity 1836–1988

The temporal and geographical variation in the history of botanical recording in the British Isles between 1836 and 1988 has been reconstructed from literature, herbarium, and field records, and related to the number and distribution of botanists. The number of botanists increased steadily to the 1930s and then five‐fold after the Second World War, and is a consistent proportion of the local population. The amount of variation in the literature, assessed from the number of pages published, number of publications, and number of floras, has changed from a low rate between 1836 and 1880, to twice that between 1890 and 1940, and increased steadily to 1988. The number of herbarium specimens collected was also low up to the 1870s and then increased three‐fold between 1870 and 1914, decreased between the World Wars, increased in the 1950s, and then decreased as conservation concerns came into play. The number of field records, now on computer, has risen dramatically since the 1930s, especially associated with major recording projects. The Botanical Society of the British Isles (BSBI) Monitoring Scheme data show a strong relationship between the number of hours spent recording at a site and the number of species recorded. The production of literature, collection of herbarium specimens, and field records also vary geographically, being concentrated in the areas in which botanists live. General patterns of recording activity are presented from a combination of the data that follow the general trends shown by the sources. There has been an increase in recording activity, with a low level between 1836 and 1870, followed by a large increase, peaking between 1890 and 1910, followed by decreases during the World Wars, with a recovery between, and a sustained increase since 1950. There is a clear trend from a high recording activity in south‐east England to low levels in Scotland and, especially, Ireland, high levels being associated with the main population areas. Temporal and geographical variations in recording activity need to be taken into account when assessing floristic change. © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society, 2006, 152 , 303–330.     

Chronic obstructive pulmonary disease: A crosstalk on nucleotide compositional dynamics and codon usage patterns of the genes involved in disease

Chronic obstructive pulmonary disease (COPD), a lung disease, affects a large number of people worldwide, leading to death. Here, we analyzed the compositional features and trends of codon usage of the genes influencing COPD to understand molecular biology, genetics, and evolutionary relationships of these genes as no work was reported yet. Coding sequences of COPD genes were found to be rich in guanine-cytosine (GC) content. A high value (34-60) of the effective number of codons of the genes indicated low codon usage bias (CUB). Correspondence analysis suggested that the COPD genes were distinct in their codon usage patterns. Relative synonymous codon usage values of codons differed between the more preferred codons and the less-preferred ones. Correlation analysis between overall nucleotides and those at third codon position revealed that mutation pressure might influence the CUB of the genes. The high correlation between GC12 and GC3 signified that directional mutation pressure might have operated at all the three codon positions in COPD genes.     

Progress bias versus status quo bias in the ethics of emerging science and technology

How should we handle ethical issues related to emerging science and technology in a rational way? This is a crucial issue in our time. On the one hand, there is great optimism with respect to technology. On the other, there is pessimism. As both perspectives are based on scarce evidence, they may appear speculative and irrational. Against the pessimistic perspective to emerging technology, it has been forcefully argued that there is a status quo bias (SQB) fuelling irrational attitudes to emergent science and technology and greatly hampering useful development and implementation. Therefore, this article starts by analysing the SQB using human enhancement as a case study. It reveals that SQB may not be as prominent in restricting the implementation of emergent technologies as claimed in the ethics literature, because SQB (a) is fuelled by other and weaker drivers than those addressed in the literature, (b) is at best one amongst many drivers of attitudes towards emergent science and technology, and (c) may not be a particularly prominent driver of irrational decision-making. While recognizing that SQB can be one driver behind pessimism, this article investigates other and counteracting forces that may be as strong as SQB. Progress bias is suggested as a generic term for the various drivers of unwarranted science and technology optimism. Based on this analysis, a test for avoiding or reducing this progress bias is proposed. Accordingly, we should recognize and avoid a broad range of biases in the assessment of emerging and existing science and technology in order to promote an open and transparent deliberation.     

A striking example of developmental bias in an evolutionary process: The “domestication syndrome”

The question of whether “developmental bias” can influence evolution is still controversial, despite much circumstantial evidence and a good theoretical argument. Here, I will argue that the domestication of mammalian species, which took place independently more than two dozen times, provides a particularly convincing example of developmental bias in evolution. The singular finding that underlies this claim is the repeated occurrence in domesticated mammals of a set of distinctive traits, none of which were deliberately selected. This phenomenon has been termed “the domestication syndrome”. In this article, I will: (a) describe the properties of the domestication syndrome; (b) show how it can be explained in terms of the operation of a specific genetic regulatory network, that which governs neural crest cell development; and (c) discuss Dmitry Belyaev's idea of “destabilizing selection,” which holds that selecting for a new behavior often entails neuroendocrine alterations that alter many aspects of development. Finally, I will argue for the potential general significance of such destabilizing selection, in combination with developmental bias, in animal evolution.