Application of Fractal Dimension for Quantifying Noise Texture in Computed Tomography Images

Purpose Evaluation of noise texture information in CT images is important for assessing image quality. Noise texture is often quantified by the noise power spectrum (NPS), which requires numerous image realizations to estimate. This study evaluated fractal dimension for quantifying noise texture as a scalar metric that can potentially be estimated using one image realization. Methods The American College of Radiology CT accreditation phantom (ACR) was scanned on a clinical scanner (Discovery CT750, GE Healthcare) at 120 kV and 25 and 90 mAs. Images were reconstructed using filtered back projection (FBP/ASIR 0%) with varying reconstruction kernels: Soft, Standard, Detail, Chest, Lung, Bone, and Edge. For each kernel, images were also reconstructed using ASIR 50% and ASIR 100% iterative reconstruction (IR) methods. Fractal dimension was estimated using the differential box‐counting algorithm applied to images of the uniform section of ACR phantom. The two‐dimensional Noise Power Spectrum (NPS) and one‐dimensional‐radially averaged NPS were estimated using established techniques. By changing the radiation dose, the effect of noise magnitude on fractal dimension was evaluated. The Spearman correlation between the fractal dimension and the frequency of the NPS peak was calculated. The number of images required to reliably estimate fractal dimension was determined and compared to the number of images required to estimate the NPS‐peak frequency. The effect of Region of Interest (ROI) size on fractal dimension estimation was evaluated. Feasibility of estimating fractal dimension in an anthropomorphic phantom and clinical image was also investigated, with the resulting fractal dimension compared to that estimated within the uniform section of the ACR phantom. Results Fractal dimension was strongly correlated with the frequency of the peak of the radially averaged NPS curve, having a Spearman rank‐order coefficient of 0.98 (P‐value \u3c 0.01) for ASIR 0%. The mean fractal dimension at ASIR 0% was 2.49 (Soft), 2.51 (Standard), 2.52 (Detail), 2.57 (Chest), 2.61 (Lung), 2.66 (Bone), and 2.7 (Edge). A reduction in fractal dimension was observed with increasing ASIR levels for all investigated reconstruction kernels. Fractal dimension was found to be independent of noise magnitude. Fractal dimension was successfully estimated from four ROIs of size 64 × 64 pixels or one ROI of 128 × 128 pixels. Fractal dimension was found to be sensitive to non‐noise structures in the image, such as ring artifacts and anatomical structure. Fractal dimension estimated within a uniform region of an anthropomorphic phantom and clinical head image matched that estimated within the ACR phantom for filtered back projection reconstruction. Conclusions Fractal dimension correlated with the NPS‐peak frequency and was independent of noise magnitude, suggesting that the scalar metric of fractal dimension can be used to quantify the change in noise texture across reconstruction approaches. Results demonstrated that fractal dimension can be estimated from four, 64 × 64‐pixel ROIs or one 128 × 128 ROI within a head CT image, which may make it amenable for quantifying noise texture within clinical images

CT Automated Exposure Control Using A Generalized Detectability Index

Purpose Identifying an appropriate tube current setting can be challenging when using iterative reconstruction due to the varying relationship between spatial resolution, contrast, noise, and dose across different algorithms. This study developed and investigated the application of a generalized detectability index (d\u27gen) to determine the noise parameter to input to existing automated exposure control (AEC) systems to provide consistent image quality (IQ) across different reconstruction approaches. Methods This study proposes a task‐based automated exposure control (AEC) method using a generalized detectability index (d\u27gen). The proposed method leverages existing AEC methods that are based on a prescribed noise level. The generalized d\u27gen metric is calculated using lookup tables of task‐based modulation transfer function (MTF) and noise power spectrum (NPS). To generate the lookup tables, the American College of Radiology CT accreditation phantom was scanned on a multidetector CT scanner (Revolution CT, GE Healthcare) at 120 kV and tube current varied manually from 20 to 240 mAs. Images were reconstructed using a reference reconstruction algorithm and four levels of an in‐house iterative reconstruction algorithm with different regularization strengths (IR1–IR4). The task‐based MTF and NPS were estimated from the measured images to create lookup tables of scaling factors that convert between d\u27gen and noise standard deviation. The performance of the proposed d\u27gen‐AEC method in providing a desired IQ level over a range of iterative reconstruction algorithms was evaluated using the American College of Radiology (ACR) phantom with elliptical shell and using a human reader evaluation on anthropomorphic phantom images. Results The study of the ACR phantom with elliptical shell demonstrated reasonable agreement between the d\u27gen predicted by the lookup table and d\u27 measured in the images, with a mean absolute error of 15% across all dose levels and maximum error of 45% at the lowest dose level with the elliptical shell. For the anthropomorphic phantom study, the mean reader scores for images resulting from the d\u27gen‐AEC method were 3.3 (reference image), 3.5 (IR1), 3.6 (IR2), 3.5 (IR3), and 2.2 (IR4). When using the d\u27gen‐AEC method, the observers’ IQ scores for the reference reconstruction were statistical equivalent to the scores for IR1, IR2, and IR3 iterative reconstructions (P \u3e 0.35). The d\u27gen‐AEC method achieved this equivalent IQ at lower dose for the IR scans compared to the reference scans. Conclusions A novel AEC method, based on a generalized detectability index, was investigated. The proposed method can be used with some existing AEC systems to derive the tube current profile for iterative reconstruction algorithms. The results provide preliminary evidence that the proposed d\u27gen‐AEC can produce similar IQ across different iterative reconstruction approaches at different dose levels

Prevalence of and reasons for women’s, family members’, and health professionals’ preferences for cesarean section in China: A mixed-methods systematic review

Background: China has witnessed a rapid increase of caesarean section (CS) rates in recent years. Several non-clinical factors have been cited as contributing to this trend including maternal request and perceived convenience. We aimed to assess preferences for mode of delivery and factors for preferences for CS in China to inform the development of future interventions to mitigate unnecessary CSs. Methods and Findings: We conducted a mixed-methods systematic review and included longitudinal, cross-sectional studies and qualitative studies in mainland China, Hong Kong and Taiwan that investigated preferences for mode of delivery among women and family members and health professionals, and the reasons underlying such preferences. We searched MEDLINE/PUBMED, EMBASE, CINAHL, Popline, PsycINFO, Global Health Library and one Chinese database (CNKI) using a combination of the following key terms “caesarean section”, “preference”, “choice”, “knowledge”, “attitude”, “culture”, “non-clinical factors”, “health professionals-patient relations” between 1990 and 2018 without language restriction. Meta-analysis of quantitative studies and meta-synthesis of qualitative studies were applied. We included 66 studies in this analysis: 47 quantitative and 19 qualitative. For the index pregnancy, the pooled proportions of preference for CS reported by women in longitudinal studies were 14% in early or middle pregnancy (95%CI 12-17%) and 21% in late pregnancy (95%CI 15-26%). In cross-sectional studies, the proportions were 17% in early or middle pregnancy (95%CI 14-20%), 22% in late pregnancy (95%CI 18-25%) and 30% at postpartum (95%CI 19-40%). Women’s preferences for CS were found to rise as pregnancy progressed (a mean difference to test preference change across longitudinal studies; mean difference 7%, 95%CI 1%-13%). One longitudinal study reported that the preference for CS among women’s partners increased from 8% in late pregnancy to 17% in the immediate postpartum. In addition, 18 quantitative studies revealed some pregnant women did not have straightforward preference for a mode of delivery, even in late pregnancy ranging from 4% to 34%. The qualitative meta-synthesis found that women’s perceptions of CS as preferable were based on prioritizing the baby’s and woman’s health and appeared to intensify through interactions with the system. Women valued the convenience of bypassing labour because of fear of pain, antagonistic relations with providers, and beliefs of deteriorating quality of care during labour and vaginal birth fostering the feeling that CS is the safest option. Health professionals’ preference for CS was influenced by financial drivers and malpractice fears. This review has some limitations, including high heterogeneity (despite sub-group and sensitivity analysis) in the quantitative analysis, and the potential for over-reporting of women’s preferences for CS in the qualitative synthesis (due to some included studies only including women who requested CS). Conclusion: Despite a minority of women expressing a preference for CS, individual, health system and socio-cultural factors converge contributing to high CS rate in mainland China, Hong Kong and Taiwan. In order to reduce the use of unnecessary CS, interventions need to address all these non-clinical factors and concerns

Level of protein kinase C activity correlates directly with resistance to adriamycin in murine fibrosarcoma cells

AbstractIn this report, we demonstrate a direct correlation between protein kinase C (PKC) activity and adriamycin (ADR) resistance in mouse fibrosarcoma cells. PKC activity was measured in four murine UV-2237M fibrosarcoma cell lines that differed in the degrees to which they expressed resistance to ADR, which is an inhibitor of PKC. A comparison of the four cell lines revealed a positive correlation between the level of PKC activity and resistance to ADR. Incubation of the cells with the PKC inhibitor H-7 produced a partial reversal of ADR resistance. Taken together, these results suggest a role for PKC in the mechanism of ADR resistance

Bivariate causal mixture model quantifies polygenic overlap between complex traits beyond genetic correlation.

Accumulating evidence from genome wide association studies (GWAS) suggests an abundance of shared genetic influences among complex human traits and disorders, such as mental disorders. Here we introduce a statistical tool, MiXeR, which quantifies polygenic overlap irrespective of genetic correlation, using GWAS summary statistics. MiXeR results are presented as a Venn diagram of unique and shared polygenic components across traits. At 90% of SNP-heritability explained for each phenotype, MiXeR estimates that 8.3 K variants causally influence schizophrenia and 6.4 K influence bipolar disorder. Among these variants, 6.2 K are shared between the disorders, which have a high genetic correlation. Further, MiXeR uncovers polygenic overlap between schizophrenia and educational attainment. Despite a genetic correlation close to zero, the phenotypes share 8.3 K causal variants, while 2.5 K additional variants influence only educational attainment. By considering the polygenicity, discoverability and heritability of complex phenotypes, MiXeR analysis may improve our understanding of cross-trait genetic architectures

SHARC-II 350 micron Observations of Thermal Emission from Warm Dust in z>=5 Quasars

We present observations of four z>= SDSS quasars at 350 micron with the SHARC-II bolometer camera on the Caltech Submillimeter Observatory. These are among the deepest observations that have been made by SHARC-II at 350 micron, and three quasars are detected at >=3 sigma significance, greatly increasing the sample of 350 micron (corresponds to rest frame wavelengths of <60 micron at z>=5), detected high-redshift quasars. The derived rest frame far-infrared (FIR) emission in the three detected sources is about five to ten times stronger than that expected from the average SED of the local quasars given the same 1450A luminosity. Combining the previous submillimeter and millimeter observations at longer wavelengths, the temperatures of the FIR-emitting warm dust from the three quasar detections are estimated to be in the range of 39 to 52 K. Additionally, the FIR-to-radio SEDs of the three 350 micron detections are consistent with the emission from typical star forming galaxies. The FIR luminosities are ~10^{13} L_solar and the dust masses are >= 10^{8}M_solar. These results confirm that huge amounts of warm dust can exist in the host galaxies of optically bright quasars as early as z~6. The universe is so young at these epochs (~1 Gyr) that a rapid dust formation mechanism is required. We estimate the size of the FIR dust emission region to be about a few kpc, and further provide a comparison of the SEDs among different kinds of dust emitting sources to investigate the dominant dust heating mechanism.Comment: 15 pages, 3 figures, accepted for publication in A

A study of microfiber phytoremediation in vertical hydroponics

Microfibers (MFs) are one of the most prevalent microplastic (MP) sub-groups found in the aquatic environment released from many sources, including household laundry. MPs pose risks to the growth rate of terrestrial/aquatic biota and through biomagnification. Although MFs can be ingested by humans, their toxic effects and potential impact on public health are not yet clearly understood. Moreover, the removal of MPs, including MFs, during wastewater treatment is a challenge, since treatment plants are not designed to collect them. Therefore, this work aims to study the potential of the in situ phytoremediation of microfibers from a domestic washing machine effluent by growing barley in a vertical hydroponic system. The temporal variation in barley growth, water quality parameters, length distribution of MFs, and their removal were evaluated over 4 weeks. We investigated the MFs&rsquo; interaction with two systems: without barley (System NP) (used as a control) and with barley (System P). The results show the barley growth is negatively affected at the end of 4 weeks, mainly by the accumulation of phosphate and the presence of fungi. However, the level of dissolved oxygen in System P is satisfactory and the presence of MFs decreases considerably (mainly for MFs &gt; 600 &micro;m) from different interactions with the barley roots. These interactions were corroborated by microscopy images. The total removal of MFs through the hydroponic system was 52% in week 2, decreasing to 42%. This is the first time that the removal of MFs has been evaluated using vertical hydroponics, which demonstrates that this phytoremediation system can be used at the household level. It also shows that vertical hydroponics, as an experimental methodology, for the analyses of MFs&rsquo; impacts on plant health has merit. It is expected that this study will contribute to new investigations of MF removal by green technologies

Authoritarianism in the Living Room: Everyday Disciplines, Senses, and Morality in Taiwan’s Military Villages

With the nationalist government – Kuomintang (KMT) – retreating from mainland China in 1949, some 600,000 military personnel relocated to Taiwan. The military seized former Japanese colonial properties and built its own settlements, establishing temporary military dependents’ villages called juancun (眷村). When the prospect of counter-attacking the mainland vanished, the KMT had to face the reality of settling permanently in Taiwan. How, then, did the KMT’s authoritarian power enter the everyday lives of its own support group? In this article I will focus on the coercive elements of KMT authoritarianism, which permeated these military villages in Taiwan. I will look at the coercive mechanisms through the analytical lens of Foucauldian discipline. I argue that disciplinary techniques such as surveillance, disciplining of the body and the senses, as well as the creation of morality regimes played an important role in the cooptation of village residents into KMT authoritarianism by normalising and naturalising it

Genome-wide analyses for personality traits identify six genomic loci and show correlations with psychiatric disorders

Personality is influenced by genetic and environmental factors1 and associated with mental health. However, the underlying genetic determinants are largely unknown. We identified six genetic loci, including five novel loci2,3, significantly associated with personality traits in a meta-analysis of genome-wide association studies (N = 123,132–260,861). Of these genomewide significant loci, extraversion was associated with variants in WSCD2 and near PCDH15, and neuroticism with variants on chromosome 8p23.1 and in L3MBTL2. We performed a principal component analysis to extract major dimensions underlying genetic variations among five personality traits and six psychiatric disorders (N = 5,422–18,759). The first genetic dimension separated personality traits and psychiatric disorders, except that neuroticism and openness to experience were clustered with the disorders. High genetic correlations were found between extraversion and attention-deficit– hyperactivity disorder (ADHD) and between openness and schizophrenia and bipolar disorder. The second genetic dimension was closely aligned with extraversion–introversion and grouped neuroticism with internalizing psychopathology (e.g., depression or anxiety)