Is the σ\sigma meson dynamically generated?

We study the problem whether the $\sigma$ meson is generated `dynamically'. A pedagogical analysis on the toy O(N) linear sigma model is performed and we find that the large $N_c$ limit and the $m_\sigma\to \infty$ limit does not commute. The sigma meson may not necessarily be described as a dynamically generated resonance. On the contrary, the sigma meson may be more appropriately described by considering it as an explicit degree of freedom in the effective lagrangian.Comment: Contribution to ``Quark Confinement and Hadron Spectrum VII'', 2--7 Sept. 2006, Ponta Delgada, Acores, Portuga

Positivity constraints on LECs of χ\chiPT lagrangian at \cO(p^6) level

Positivity constraints on the LECs of \cO(p^6) $\chi$PT lagrangian are discussed. We demonstrate that the constraints are automatically satisfied inside the Mandelstam triangle for $\pi\pi$ scatterings, when $N_C$ is large. Numerical tests are made in the $N_C=3$ case, and it is found that these constraints are also well respected.Comment: 9 pages with 2 eps figure

Is the f0(600)f_0(600) meson a dynamically generated resonance? -- a lesson learned from the O(N) model and beyond

O(N) linear $\sigma$ model is solvable in the large $N$ limit and hence provides a useful theoretical laboratory to test various unitarization approximations. We find that the large $N_c$ limit and the $m_\sigma\to \infty$ limit do not commute. In order to get the correct large $N_c$ spectrum one has to firstly take the large $N_c$ limit. We argue that the $f_0(600)$ meson may not be described as generated dynamically. On the contrary, it is most appropriately described at the same level as the pions, i.e, both appear explicitly in the effective lagrangian. Actually it is very likely the $\sigma$ meson responsible for the spontaneous chiral symmetry breaking in a lagrangian with linearly realized chiral symmetry.Comment: 15 pages, 3 figurs; references added; discussions slightly modified; revised version accepted by IJMP

Pure multiplicative stochastic resonance of anti-tumor model with seasonal modulability

The effects of pure multiplicative noise on stochastic resonance in an anti-tumor system modulated by a seasonal external field are investigated by using theoretical analyses of the generalized potential and numerical simulations. For optimally selected values of the multiplicative noise intensity quasi-symmetry of two potential minima and stochastic resonance are observed. Theoretical results and numerical simulations are in good quantitative agreement.Comment: 5 pages, 5 figure

Spatiotemporal Fluctuation Induced Transition in a Tumor Model with Immune Surveillance

We report on a simple model of spatial extend anti-tumor system with a fluctuation in growth rate, which can undergo a nonequilibrium phase transition. Three states as excited, sub-excited and non-excited states of a tumor are defined to describe its growth. The multiplicative noise is found to be double-face: The positive effect on a non-excited tumor and the negative effect on an excited tumor.Comment: 8pages,5figure

Arsenic and Fluoride Exposure in Drinking Water: Children’s IQ and Growth in Shanyin County, Shanxi Province, China

BACKGROUND: Recently, in a cross-sectional study of 201 children in Araihazar, Bangladesh, exposure to arsenic (As) in drinking water has been shown to lower the scores on tests that measure children’s intellectual function before and after adjustment for sociodemographic features. OBJECTIVES: We investigated the effects of As and fluoride exposure on children’s intelligence and growth. METHODS: We report the results of a study of 720 children between 8 and 12 years of age in rural villages in Shanyin county, Shanxi province, China. The children were exposed to As at concentrations of 142 ± 106 μg/L (medium-As group) and 190 ± 183 μg/L (high-As group) in drinking water compared with the control group that was exposed to low concentrations of As (2 ± 3 μg/L) and low concentrations of fluoride (0.5 ± 0.2 mg/L). A study group of children exposed to high concentrations of fluoride (8.3 ± 1.9 mg/L) but low concentrations of As (3 ± 3 μg/L) was also included because of the common occurrence of elevated concentrations of fluoride in groundwater in our study area. A standardized IQ (intelligence quotient) test was modified for children in rural China and was based on the classic Raven’s test used to determine the effects of these exposures on children’s intelligence. A standardized measurement procedure for weight, height, chest circumference, and lung capacity was used to determine the effects of these exposures on children’s growth. RESULTS: The mean IQ scores decreased from 105 ± 15 for the control group, to 101 ± 16 for the medium-As group (p < 0.05), and to 95 ± 17 for the high-As group (p < 0.01). The mean IQ score for the high-fluoride group was 101 ± 16 and significantly different from that of the control group (p < 0.05). Children in the control group were taller than those in the high-fluoride group (p < 0.05); weighed more than the those in the high-As group (p < 0.05); and had higher lung capacity than those in the medium-As group (p < 0.05). CONCLUSIONS: Children’s intelligence and growth can be affected by high concentrations of As or fluoride. The IQ scores of the children in the high-As group were the lowest among the four groups we investigated. It is more significant that high concentrations of As affect children’s intelligence. It indicates that arsenic exposure can affect children’s intelligence and growth

Rapid increase of scrub typhus incidence in Guangzhou, southern China, 2006-2014

Background: In the last decade, scrub typhus (ST) has been emerging or re-emerging in some areas of Asia, including Guangzhou, one of the most affected endemic areas of ST in China. Methods: Based on the data on all cases reported in Guangzhou from 2006 to 2014, we characterized the epidemiological features, and identified environmental determinants for the spatial distribution of ST using a panel negative binomial model. Results: A total of 4821 scrub typhus cases were reported in Guangzhou during 2006-2014. The annual incidence increased noticeably and the increase was relatively high and rapid in rural townships and among elderly females. The majority of cases (86.8%) occurred during May-October, and farmers constituted the majority of the cases, accounting for 33.9% in urban and 61.6% in rural areas. The number of housekeeper patients had a rapid increment in both rural and urban areas during the study period. Atmospheric pressure and relative humidity with lags of 1 or 2 months, distributions of broadleaved forest and rural township were identified as determinants for the spatiotemporal distribution of scrub typhus. Conclusion: Our results indicate that surveillance and public education need to be focused on the elderly farmers in rural areas covered with broadleaf forest in southern China

A Novel Inhibitor of Human La Protein with Anti-HBV Activity Discovered by Structure-Based Virtual Screening and In Vitro Evaluation

Background: Over 350 million people worldwide are infected with hepatitis B virus (HBV), a major cause of liver failure and hepatocellular carcinoma. Current therapeutic agents are highly effective, but are also associated with development of viral resistance. Therefore, strategies for identifying other anti-HBV agents with specific, but distinctive mechanisms of action are needed. The human La (hLa) protein, which forms a stabilizing complex with HBV RNA ribonucleoprotein to promote HBV replication, is a promising target of molecular therapy. Aims: This study aimed to discover novel inhibitors of hLa that could inhibit HBV replication and expression. Methods: A multistage molecular docking approach was used to screen a Specs database and an in-house library against hLa binding sites. Sequential in vitro evaluations were performed to detect potential compounds with high scores in HepG2.2.15 cells. Results: Of the 26 potential compounds with high scores chosen for experimental verification, 12 had HBV DNA inhibition ratios of less than 50 % with P,0.05. Six had significant inhibition of HBV e antigen (HBeAg) levels, and 13 had significant inhibition of HBV surface antigen (HBsAg) levels by in vitro assays. Compounds HBSC-11, HBSC-15 and HBSC-34 (HBSC is system prefix for active compounds screened by the library) were selected for evaluation. HBSC-11 was found to have an obvious inhibitory effect on hLa transcription and expression

Polyclonal rabbit anti-murine plasmacytoma cell globulins induce myeloma cells apoptosis and inhibit tumour growth in mice

Multiple myelomas (MMs) are etiologically heterogeneous and there are limited treatment options; indeed, current monoclonal antibody therapies have had limited success, so more effective antibodies are urgently needed. Polyclonal antibodies are a possible alternative because they target multiple antigens simultaneously. In this study, we produced polyclonal rabbit anti-murine plasmacytoma cell immunoglobulin (PAb) by immunizing rabbits with the murine plasmacytoma cell line MPC-11. The isolated PAb bound to plasma surface antigens in several MM cell lines, inhibited their proliferation as revealed by MTT assay, and induce apoptosis as indicated by flow cytometry, microscopic observation of apoptotic changes in morphology, and DNA fragmentation on agarose gels. The cytotoxicity of PAb on MPC-11 cell lines was both dose-dependent and time-dependent; PAb exerted a 50% inhibitory effect on MPC-11 cell viability at a concentration of 200 µg/ml in 48 h. Flow cytometry demonstrated that PAb treatment significantly increased the number of apoptotic cells (48.1%) compared with control IgG (8.3%). Apoptosis triggered by PAb was confirmed by activation of caspase-3, -8, and -9. Serial intravenous or intraperitoneal injections of PAb inhibited tumour growth and prolonged survival in mice bearing murine plasmacytoma, while TUNEL assay demonstrated that PAb induced statistically significant apoptosis (P < 0.05) compared to control treatments. We conclude that PAb is an effective agent for in vitro and in vivo induction of apoptosis in multiple myeloma and that exploratory clinical trials may be warranted