The Causes of Chronic and Transient Poverty and Their Implications for Poverty Reduction Policy in Rural China

The study focuses on two components of total poverty: chronic and transient poverty, and investigates their relative importance in total observed poverty, as well as the determinants of each components. We found that transient poverty accounts for a large proportion of total poverty observed in the poor rural areas of China. By analyzing the determinants of the two types of poverty, we found that household demographic characteristics, such as age of the head of households, family sizes, labour participation ratio, and educational level of the head of the households, are very important to the poverty status of households. These factors matter more to chronic poverty than transient poverty, and have greater impacts on the poverty measured by consumption than that measured by income. Besides the demographic factors of households, other household factors like physical stocks, the composition of income, and the amount of cultivated lands also have significant effects on both chronic and transient poverty. It is also confirmed that change in cash holding and saving and borrowing grain are used by rural households to cope with income variation and smooth their consumption. Attributes of community where the households reside are also important to poverty. With very few exceptions, we did not find that poverty programs have significant impact on poverty reduction at the households' level. We interpreted this as the poverty programs benefiting the wealthy more than the poor in a given poor area. The main reason for this could be that the implementation design of these programs fails to target the poor.Income risk, chronic poverty, transient poverty, poverty program evaluation, China

The autophagic degradation of cytosolic pools of peroxisomal proteins by a new selective pathway.

Damaged or redundant peroxisomes and their luminal cargoes are removed by pexophagy, a selective autophagy pathway. In yeasts, pexophagy depends mostly on the pexophagy receptors, such as Atg30 for Pichia pastoris and Atg36 for Saccharomyces cerevisiae, the autophagy scaffold proteins, Atg11 and Atg17, and the core autophagy machinery. In P. pastoris, the receptors for peroxisomal matrix proteins containing peroxisomal targeting signals (PTSs) include the PTS1 receptor, Pex5, and the PTS2 receptor and co-receptor, Pex7 and Pex20, respectively. These shuttling receptors are predominantly cytosolic and only partially peroxisomal. It remains unresolved as to whether, when and how the cytosolic pools of peroxisomal receptors, as well as the peroxisomal matrix proteins, are degraded under pexophagy conditions. These cytosolic pools exist both in normal and mutant cells impaired in peroxisome biogenesis. We report here that Pex5 and Pex7, but not Pex20, are degraded by an Atg30-independent, selective autophagy pathway. To enter this selective autophagy pathway, Pex7 required its major PTS2 cargo, Pot1. Similarly, the degradation of Pex5 was inhibited in cells missing abundant PTS1 cargoes, such as alcohol oxidases and Fox2 (hydratase-dehydrogenase-epimerase). Furthermore, in cells deficient in PTS receptors, the cytosolic pools of peroxisomal matrix proteins, such as Pot1 and Fox2, were also removed by Atg30-independent, selective autophagy, under pexophagy conditions. In summary, the cytosolic pools of PTS receptors and their cargoes are degraded via a pexophagy-independent, selective autophagy pathway under pexophagy conditions. These autophagy pathways likely protect cells from futile enzymatic reactions that could potentially cause the accumulation of toxic cytosolic products.Abbreviations: ATG: autophagy related; Cvt: cytoplasm to vacuole targeting; Fox2: hydratase-dehydrogenase-epimerase; PAGE: polyacrylamide gel electrophoresis; Pot1: thiolase; PMP: peroxisomal membrane protein; Pgk1: 3-phosphoglycerate kinase; PTS: peroxisomal targeting signal; RADAR: receptor accumulation and degradation in the absence of recycling; RING: really interesting new gene; SDS: sodium dodecyl sulphate; TCA, trichloroacetic acid; Ub: ubiquitin; UPS: ubiquitin-proteasome system Vid: vacuole import and degradation

Time scales of epidemic spread and risk perception on adaptive networks

Incorporating dynamic contact networks and delayed awareness into a contagion model with memory, we study the spreading patterns of infectious diseases in connected populations. It is found that the spread of an infectious disease is not only related to the past exposures of an individual to the infected but also to the time scales of risk perception reflected in the social network adaptation. The epidemic threshold $p_{c}$ is found to decrease with the rise of the time scale parameter s and the memory length T, they satisfy the equation $p_{c} =\frac{1}{T}+ \frac{\omega T}{a^s(1-e^{-\omega T^2/a^s})}$. Both the lifetime of the epidemic and the topological property of the evolved network are considered. The standard deviation $\sigma_{d}$ of the degree distribution increases with the rise of the absorbing time $t_{c}$, a power-law relation $\sigma_{d}=mt_{c}^\gamma$ is found

Management Letter, Year Ended June 30, 1999

The intestinal microbiome is essential in humans to maintain physiological balance and nutrition metabolism. Laparoscopic cholecystectomy due to gallstone disease and cholecystitis can cause intestinal microbial dysbiosis, and following bile acid metabolism dysfunction, positions the patient at high risk of colorectal cancer. However, little is known regarding intestinal microbiota characteristics in post-cholecystectomy patients. Here, we compared the microbial composition of cholecystectomy patients with that of a healthy population. We determined that cholecystectomy eliminated aging-associated fecal commensal microbiota and further identified several bile acid metabolism-related bacteria as contributors of colorectal cancer incidence via elevation of secondary bile acids.Significance statementWe identified aging-associated fecal microbiota in a healthy population, which was lost in cholecystectomy patients. Absent intestinal bacteria, such as Bacteroides, were negatively related to secondary bile acids and may be a leading cause of colorectal cancer incidence in cholecystectomy patients. Our study provides novel insight into the connection between cholecystectomy-altered gut microbiota and colorectal carcinoma, which is of value for colorectal cancer diagnosis and management

COMPARING PRICE MOVEMENTS OF OPTIONS AND THE UNDERLYING INDEX

Research Project (M.B.A.) - Simon Fraser Universit

Video-rate centimeter-range optical coherence tomography based on dual optical frequency combs by electro-optic modulators

Imaging speed and range are two important parameters for optical coherence tomography (OCT). A conventional video-rate centimeter-range OCT requires an optical source with hundreds of kHz repetition rate and needs the support of broadband detectors and electronics (>1 GHz). In this paper, a type of video-rate centimeter-range OCT system is proposed and demonstrated based on dual optical frequency combs by leveraging electro-optic modulators. The repetition rate difference between dual combs, i.e. the A-scan rate of dual-comb OCT, can be adjusted within 0~6 MHz. By down-converting the interference signal from optical domain to radio-frequency domain through dual comb beating, the down-converted bandwidth of the interference signal is less than 22.5 MHz which is at least two orders of magnitude lower than that in conventional OCT systems. A LabVIEW program is developed for video-rate operation, and the centimeter imaging depth is proved by using 10 pieces of 1-mm thick glass stacked as the sample. The effective beating bandwidth between two optical comb sources is 7 nm corresponding to ~108 comb lines, and the axial resolution of the dual-comb OCT is 158 µm. Dual optical frequency combs provide a promising solution to relax the detection bandwidth requirement in fast long-range OCT systems