Bifurcations of limit cycles from cubic Hamiltonian systems with a center and a homoclinic saddle-loop

It is provedin this paper that the maximum number of limit cycles of system [formula] is equal to two in the finite plane, where [formula]. This is partial answer to the seventh question in [2], posed by Arnold

Abelian integrals of quadratic hamiltonian vector fields with an invariant straight line

We prove that the lowest upper bound for the number of isolated zeros of the Abelian integrals associated to quadratic Hamiltonian vector fields having a center and an invariant straight line after quadratic perturbations is on

QUANTITATIVE STRUCTURE ACTIVITY RELATIONSHIPS (QSAR) FOR BINARY MIXTURES AT NON-EQUITOXIC RATIOS BASED ON TOXIC RATIOS-EFFECTS CURVES

The present study proposed a QSAR model to predict joint effects at non-equitoxic ratios for binary mixtures containing reactive toxicants, cyanogenic compounds and aldehydes. Toxicity of single and binary mixtures was measured by quantifying the decrease in light emission from the Photobacterium phosphoreum for 15 min. The joint effects of binary mixtures (TUsum) can thus be obtained. The results showed that the relationships between toxic ratios of the individual chemicals and their joint effects can be described by normal distribution function. Based on normal distribution equations, the joint effects of binary mixtures at non-equitoxic ratios (TUsumn:m ) can be predicted quantitatively using the joint effects at equitoxic ratios (TUsum1:1). Combined with a QSAR model of TUsum1:1 in our previous work, a novel QSAR model can be proposed to predict the joint effects of mixtures at non-equitoxic ratios (TUsum n:m ). The proposed model has been validated using additional mixtures other than the one used for the development of the model. Predicted and observed results were similar (p\u3e0.05). This study provides an approach to the prediction of joint effects for binary mixtures at non-equitoxic ratios

Effect of insulin resistance on gonadotropin and bone mineral density in nondiabetic postmenopausal women

ObjectiveThe effects of insulin resistance (IR) on bone mineral density (BMD) are unclear. This investigation aimed to assess the impact of IR and hyperinsulinemia on bone health. Determine whether IR mediates the link between follicle-stimulating hormone (FSH) and bone mass in nondiabetic postmenopausal women.DesignRetrospective cross-sectional study.SettingHealth checkup center of Hangzhou Women’s Hospital.MethodsThis study comprised 437 nondiabetic postmenopausal women. BMD was evaluated using dual-energy X-rays. Fasting sera were analyzed for insulin and glucose levels, and indicators related to IR were determined. By pathway analysis, we examined the indirect effects of FSH on BMD via the mediators Homeostatic Model Assessment for insulin resistance (HOMA-IR) and fasting insulin (FINS) after correction for confounding factors.ResultAfter adjusting for age and body mass index (BMI) in linear regression, HOMA-IR and FINS were linked with FSH (P<0.05). IR was stronger among women in the normal BMD group than those in the osteoporosis or osteopenia group. In unadjusted models, BMD was greater in those with higher HOMA-IR and FINS (β=0.027, P=0.006 and β=0.033, P=0.003, respectively). After correcting for BMI and other possible variables, these associations remained. In addition, path models for FSH demonstrated a negative association with BMD by HOMA-IR (95% confidence interval [CI]: -0.0174 to -0.0014) and FINS (95% CI: -0.0188 to -0.002).ConclusionGreater IR was associated with increased BMD in nondiabetic postmenopausal women, regardless of BMI and other variables. HOMA-IR or FINS could play a novel mediating role in FSH-induced BMD suppression

A Comparison of the Use of Social Media in China and UK Higher Education in Art and Design Subjects.

Purpose–The purpose of this paper is to compare the use of WeChat in China vs. Facebook/ Youtube/ Blog/ Instagram in the UK in higher education practice, based on a case study in art and design subjects between a Chinese and a British university(Ningbo University and University of Huddersfield). Methodology –A combination of literature reviews, action research, peer observation and semi-structured interviews. The research consists of two parts: one was conducted in the project An Action Research of Blended Learning Mode Based on WeChat in China, funded by the Department of Education of Zhejiang Province, and the other part results from the Visiting Scholar Programme in the UK funded by K.C. Wong Education Foundation, Hong Kong. Findings – The findings represent similarities and differences between the Ningbo University and the University of Huddersfield relating to the use of social media and the strategy applying instructional technology in art and design subjects. It mainly indicates the potentially useful, pros and cons of social media in higher education practice, and presents strategies and innovation practices of adopting social media in creative arts and design subjects, including instant dissemination of ideas and processes, dynamic atmosphere of classrooms and studios, assessment and feedback, and students’ portfolios. Originality/value – The paper provides a cross-cultural perspective on sharing the knowledge and good practice of developing or enhancing the use of co-created social resources, strategies and technologies to meet the needs of the future all over the worl

Polynomial systems : a lower bound for the weakened 16th Hilbert problem

In this paper we provide the greatest lower bound about the number of (non-infinitesimal) limit cycles surrounding a unique singular point for a planar polynomial differential system of arbitrary degree

Studies of the Molecular Mechanism and Signaling Regulation of Autophagy in Saccharomyces Cerevisiae.

Autophagy is a highly conserved cellular degradation process in which portions of cytosol and organelles are sequestered into a double-membrane vesicle, an autophagosome, and delivered into a degradative organelle, the vacuole/lysosome, for breakdown and eventual recycling of the resulting macromolecules. Malfunction of autophagy has been linked to a wide range of human pathologies, including cancer, neurodegeneration and pathogen infection. Identification of many autophagy-related, ATG, genes in yeast that are essential to drive this cellular process, and the finding of orthologs in other organisms, reveals the conservation of the autophagic machinery in all eukaryotes. In addition to this, complex signaling cascades controlling autophagy have also begun to emerge, with TOR as a central but far from exclusive player. In this thesis, (1) we summarize our current knowledge about the machinery and molecular mechanism of autophagy. (2) We highlight the recent advances in identifying and understanding the core molecular machinery and signaling pathways that are involved in mammalian autophagy. (3) We elucidate a molecular mechanism for linking the degradative and recycling roles of autophagy. We show that in contrast to published studies Atg22 is not directly required for the breakdown of autophagic bodies within the lysosome/vacuole. Instead, we demonstrate that Atg22, Avt3 and Avt4 are redundant vacuolar effluxers, which mediate the efflux of leucine and other amino acids resulting from autophagic degradation. The release of autophagic amino acids allows the maintenance of protein synthesis and viability during nitrogen starvation. We propose a “recycling” model that includes the efflux of macromolecules from the lysosome/vacuole as the final step of autophagy. (4) We used genetic analyses to elucidate the mechanism by which the stress-responsive, cyclin-dependent kinase, Pho85 and its corresponding cyclins antagonistically modulate autophagy in Saccharomyces cerevisiae. When complexed with cyclins Pho80 and Pcl5, Pho85 negatively regulates autophagy through downregulating the protein kinase Rim15, and the transcription factors Pho4 and Gcn4. The cyclins Clg1, Pcl1 and Pho80, in concert with Pho85, positively regulate autophagy through promoting the degradation of Sic1, a negative regulator of autophagy that targets Rim15. Our results suggest a model in which Pho85 has opposing roles in autophagy regulation.Ph.D.Molecular, Cellular, and Developmental BiologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/75834/1/zfyang_1.pd

Induction of defensive enzymes (isozymes) during defense against two different fungal pathogens in pear calli

Activities of defensive enzymes peroxidase (POD), superoxide dismutase (SOD), catalase (CAT), polyphenol oxidase (PPO) and esterase (EST) and their isozymes in pear calli were studied to reveal their role in the defensive response to different fungal infections and to find some clues to enhance their antimicrobial properties. The results confirm the fact that the activities and isozymes of these five enzymes showed differences in response to different fungal infections. After the inoculation of two different fungi for the same calli, its defensive enzymes’ activities changed relatively when compared with those of the control and in Botryosphaeria berengriana f.sp. piricola (BBP)-infected calli, the enzymes’ activities changed more significantly than those of Monilinia fructigena Honcy (MFH). Meanwhile, more new isozymes were induced by BBP infection. These are in agreement with the fact that the BBP-infected calli decay was slower than that of the MFH. These results suggest that enhancing defensive enzymes’ activities and inducing new isozymes may be related to mitigating pathogen-induced oxidative damage which result in the decrease of calli decay, and this implies that antioxidant defense response may be involved in the mechanisms of plant against fungal pathogen.Keywords: Pear callus, fungi infection, defense enzyme, isozyme, biochemical defense mechanis

HLA-DRB1 May Be Antagonistically Regulated by the Coordinately Evolved Promoter and 3′-UTR under Stabilizing Selection

HLA-DRB1 is the most polymorphic MHC (major histocompatibility complex) class II gene in human, and plays a crucial role in the development and function of the immune system. Extensive polymorphisms exist in the promoter and 3′-UTR of HLA-DRB1, especially a LTR (Long terminal repeat) element in the promoter, which may be involved in the expression regulation. However, it remains unknown how the polymorphisms in the whole promoter region and 3′-UTR to regulate the gene expression. In this study, we investigated the extensive polymorphisms in the HLA-DRB1 promoter and 3′-UTR, and how these polymorphisms affect the gene expression in both independent and jointly manners. It was observed that most of the haplotypes in the DRB1 promoter and 3′-UTR were clustered into 4 conserved lineages (H1, H2, H3 and H4), and showed high linkage disequilibrium. Compared with H1 and H2 lineage, a LTR element in the promoter of H3 and H4 lineage significantly suppressed the promoter activity, whereas the activity of the linked 3′-UTR increased, leading to no apparent difference in the final expression product between H1/H2 and H3/H4 lineage. Nevertheless, compared with the plasmid with a promoter and 3′-UTR from the same lineage, the recombinant plasmid with a promoter from H2 and a 3′-UTR from H3 showed about double fold increased luciferase activity, Conversely, the recombinant plasmid with a promoter from H3 and a 3′-UTR from H2 resulted in about 2-fold decreased luciferase activity. These results indicate that the promoter and 3′-UTR of HLA-DRB1 may antagonistically regulate the gene expression, which may be subjected to stabilizing selection. These findings may provide a novel insight into the mechanisms of the diseases associated with HLA-DRB1 genes