Development of A Kinetic Model For Loop-Free Colonoscopy Technology

The colonoscope is an important tool in diagnosis and management of diseases of the colon. One of the ongoing challenges with this device is that the colonoscope may form a loop together with the colon during the procedure. The result of the loop is that further insertion of the scope in the colon may not be possible. The loop may also cause risks of perforation of the colon and pain in the patient. There are currently several existing devices to overcome loop formation in colonoscopy, some of which have been introduced in clinical work. However, empirical assessment shows that these devices do not work very well. This is the motivation for the research presented in this thesis. In this thesis, a new paradigm of thinking, “doctor-assisted colonoscopy,” is proposed to overcome loop formation. In this new approach, the physician’s role is enhanced with new information that is acquired by sensors outside the human body and inferred from the mathematical model. It is referred to as a kinetic model due to the fact that this model describes the kinetic behaviour of the scope. This thesis is devoted to development of this kinetic model. In this study, the model of the colonoscope and the model of the colon are developed based on the Timoshenko beam theory, and parameters in both models are determined by the experiments. The following conclusions then are made: (1) self-locking of the colonoscope is the most basic cause for a loop to occur, while structural instability of the colonsocope is dependent on the self-locking; (2) both the scope and the colon can be well represented with the Timoshenko beam elements and the Linear Complementary Problem (LCP) formulation derived from Signorini’s law, and Coulom’s law for representation of interactions between the colon and scope is adequate; (3) there are effects from the location, looping, and tip deflection of the scope on flexural rigidity of the scope. Approximately, the flexural rigidity of the CF-Q160L colonoscope ranges from 300 to 650 N•cm2, and its accuracy is proven by a good agreement between the model predicted result and experimental result; (4) Rayleigh damping for the CF-Q160L colonoscope depends more on the mass matrix [M] of the colonoscope than the stiffness matrix [K], which is evident by the large coefficient value of “alpha” (0.3864) and the small coefficient value of “beta” (0.0164). The contributions of this thesis are: (1) the finding that the main cause of the loop is not structural instability of the colonoscope but rather self-locking of the colonoscope, which could lead to design of a “new-generation” colonoscope to avoid the loop; (2) a systematic evaluation of the existing colonoscopy technologies based on the well-proven Axiomatic Design Theory (ADT), which will serve as a guideline for the development of future new colonoscopes in future; (3) an approach to developing a kinetic model of the colonoscope useful to modeling similar objects such as a catheter guide-wire; (4) a novel ex-vivo colonoscopy test-bed with the kinetic and kinematic measurements useful for validation of new designs in colonoscopy technology and also useful for training physicians who perform the colonoscopy procedure; and (5) a new paradigm of thinking for colonoscopy called “doctor-assisted colonoscopy,” which has potential applications to other medical procedures such as catheter-based procedures

A Recalibrated Molecular Clock and Independent Origins for the Cholera Pandemic Clones

Cholera, caused by Vibrio cholerae, erupted globally from South Asia in 7 pandemics, but there were also local outbreaks between the 6th (1899–1923) and 7th (1961–present) pandemics. All the above are serotype O1, whereas environmental or invertebrate isolates are antigenically diverse. The pre 7th pandemic isolates mentioned above, and other minor pathogenic clones, are related to the 7th pandemic clone, while the 6th pandemic clone is in the same lineage but more distantly related, and non-pathogenic isolates show no clonal structure. To understand the origins and relationships of the pandemic clones, we sequenced the genomes of a 1937 prepandemic strain and a 6th pandemic isolate, and compared them with the published 7th pandemic genome. We distinguished mutational and recombinational events, and allocated these and other events, to specific branches in the evolutionary tree. There were more mutational than recombinational events, but more genes, and 44 times more base pairs, changed by recombination. We used the mutational single-nucleotide polymorphisms and known isolation dates of the prepandemic and 7th pandemic isolates to estimate the mutation rate, and found it to be 100 fold higher than usually assumed. We then used this to estimate the divergence date of the 6th and 7th pandemic clones to be about 1880. While there is a large margin of error, this is far more realistic than the 10,000–50,000 years ago estimated using the usual assumptions. We conclude that the 2 pandemic clones gained pandemic potential independently, and overall there were 29 insertions or deletions of one or more genes. There were also substantial changes in the major integron, attributed to gain of individual cassettes including copying from within, or loss of blocks of cassettes. The approaches used open up new avenues for analysing the origin and history of other important pathogens

Left-behind villages, left-behind children: Migration and the cognitive achievement of rural children in China

© 2019 John Wiley & Sons, Ltd. Although the potential effects of migration on the cognitive development of children in origin communities reflect both household- and community-level processes, few studies have examined how community-level migration affects child cognitive development. By applying multilevel methods to nationally representative data of 2,248 children from 427 villages in China, we examine whether village migration intensity influences child cognitive ability and if so, what accounts for this influence. The findings suggest lower cognitive achievement in communities that experience high migration intensity. Living in a community with a large proportion of people who have migrated away from the community is associated with a 3.57-unit decrease in verbal scores and a 1.54-unit decrease in maths scores, which is equivalent to missing 1.67 and 0.87 years of schooling, respectively. A possible explanation for this effect is the change in demographic composition such that communities are depleted of better educated adults

Improved Robust Stability Criterion of Networked Control Systems with Transmission Delays and Packet Loss

The problem of stability analysis for a class of networked control systems (NCSs) with network-induced delay and packet dropout is investigated in this paper. Based on the working mechanism of zero-order holder, the closed-loop NCS is modeled as a continuous-time linear system with input delay. By introducing a novel Lyapunov-Krasovskii functional which splits both the lower and upper bounds of the delay into two subintervals, respectively, and utilizes reciprocally convex combination technique, a new stability criterion is derived in terms of linear matrix inequalities. Compared with previous results in the literature, the obtained stability criterion is less conservative. Numerical examples demonstrate the validity and feasibility of the proposed method

Parental Migration and Early Childhood Development in Rural China

Background In rural China, over 61 million children age 0-17 (28% of all rural children) are left behind by at least one parent seeking employment elsewhere. Little empirical evidence exists regarding how parental migration in the first few years of children’s life affects early child development, and whether the effect is dependent on the family social economic status (SES) when a child was born. This study aims to address this gap. Methods The data used in the analyses are derived from three waves of the China Family Panel Studies (CFPS), collected in 2010, 2012 and 2014. A number of early childhood development outcomes are assessed: height, childhood illness, pre-primary school enrollment, social behavioral development and intermediate outcomes including cognitive stimulation and breastfeeding duration. Capitalizing on the longitudinal nature of the CFPS, we address the complexity and dynamic processes of family migration strategies by distinguishing various types of migration, taking into account of timing, intensity and cumulative of exposure to parental migration. An interaction term between initial SES and various independent variables was used to test differential impact. Results By age 5, over 52% of rural children experienced being left-behind by at least one parent. Compared to children never experienced parental migration, outmigration of mother is associated with 0.17 lower probability of being breastfed for at least 6 months (p\u3c0.05). Experience being left-behind by both parents is negatively associated with linear growth (p\u3c0.1), and longer exposure is more detrimental. Experienced parental migration during age 0-1 is associated with higher likelihood of being ill in the preceding 4 weeks (p\u3c0.1). For ECD outcomes of preschool enrollment, social behavior score and early cognitive stimulation, we found significant interaction between initial family SES and ever experienced both parent migration; and between initial family SES and cumulative exposure to both parent migration for childhood illness, early cognitive stimulation and preschool enrollment. Conclusion Overall, children experienced parental migration exhibit few significant differences on ECD outcomes relative to children constantly living with both parents. For children from the poorest families migration of both parents increases the chance of their children to get pre-primary school education, it has not, however, benefited their physical or social behavioral development. Contrary to the hope of most migrants, labor migration confers little significant advantage to their left-behind children

Parental Migration and Children’s Early Childhood Development: A Prospective Cohort Study of Chinese Children

© 2021, The Author(s), under exclusive licence to Springer Nature B.V. part of Springer Nature. In the developing world, children are at high risk of growing up without one or both parents for extended periods of time during childhood, largely due to parental labor migration. Limited work has studied the potential impact of parental migration on early childhood development (ECD), and longitudinal data to address this question is particularly lacking. Using three waves of the China Family Panel Studies data collected in 2010, 2012 and 2014, the current study examines the association between parental migration and a number of ECD outcomes. We address the complexity and dynamic processes of family migration by categorizing patterns of parental migration during the first 5 years of children’s lives, taking into account timing and sequencing of parental migration events, as well as children’s cumulative experience with parental migration. We then associate various patterns of parental migration with the trajectories of childhood linear growth, childhood illness and home environment from age 1 to age 5, and with pre-primary school enrollment, social behavioral development, and cognitive stimulation measured at age 4 or 5. Our findings indicate that parental migration, regardless of the number of absent parents, was not associated with childhood illness, behavior, or preschool enrollment. We observe a negative association between parental migration and both cognitive stimulation and the quality of the home environment. The strength of the associations is stronger when migration involved two parents. Children of returned migrants exhibit a slower rate of linear growth, on average. The results are largely insensitive to the timing of parental migration. The implications of lower levels of cognitive stimulation and quality of the home environment on left-behind children’s cognitive development deserve further investigation

Gradation and Rheological Characteristics of Glacial Debris Flow along the Kangding–Linzhi Section of Sichuan–Tibet Railway

To date, most research on the characteristics of glacial debris flow along the Sichuan–Tibet railway has focused on numerical simulations and remote sensing, resulting in a lack of direct experimental data from debris flow samples. Therefore, in the present study, a field investigation was conducted along the Sichuan–Tibet railway, and 55 samples of glacial debris flow deposits were systematically analyzed to determine their grading and rheological properties. This is the first systematic experimental study on glacial debris flow deposits. The results showed that the proportion of coarse particles was high and the proportion of fine particles was low in the glacial debris flow along the Sichuan–Tibet railway. The average gravel and sand contents were 37.8% and 58%, respectively, and the average contents of silt and clay were 3.7% and 0.47%, respectively. The average fractal dimension was 2.1507, which is much greater than that of viscous debris flow. Under the same gravity and shear rate, the stress of typical glacial debris flow was significantly less than that of viscous debris flow, whereas the variability of the stress was more significant. These findings will contribute to revealing the movement rules and disaster risk of glacier debris flow along the Sichuan–Tibet railway and have considerable theoretical and practical significance for ensuring safety during both its construction and later operation

Identifying Wild Versus Cultivated Gene-Alleles Conferring Seed Coat Color and Days to Flowering in Soybean

Annual wild soybean (G. soja) is the ancestor of the cultivated soybean (G. max). To reveal the genetic changes from soja to max, an improved wild soybean chromosome segment substitution line (CSSL) population, SojaCSSLP5, composed of 177 CSSLs with 182 SSR markers (SSR-map), was developed based on SojaCSSLP1 generated from NN1138-2(max)×N24852(soja). The SojaCSSLP5 was genotyped further through whole-genome resequencing, resulting in a physical map with 1366 SNPLDBs (SNP linkage-disequilibrium blocks), which are composed of more markers/segments, shorter marker length and more recombination breakpoints than the SSR-map and caused 721 new wild substituted segments. Using the SNPLDB-map, two loci co-segregating with seed-coat color (SCC) and six loci for days to flowering (DTF) with 88.02% phenotypic contribution were identified. Integrated with parental RNA-seq and DNA-resequencing, two SCC and six DTF candidate genes, including three previously cloned (G, E2 and GmPRR3B) and five newly detected ones, were predicted and verified at nucleotide mutant level, and then demonstrated with the consistency between gene-alleles and their phenotypes in SojaCSSLP5. In total, six of the eight genes were identified with the parental allele-pairs coincided to those in 303 germplasm accessions, then were further demonstrated by the consistency between gene-alleles and germplasm phenotypes. Accordingly, the CSSL population integrated with parental DNA and RNA sequencing data was demonstrated to be an efficient platform in identifying candidate wild vs. cultivated gene-alleles