Shrinkage Estimation Using Ranked Set Samples

The purpose of this article is two-fold. First, we consider the ranked set sampling (RSS) estimation and testing hypothesis for the parameter of interest (population mean). Then, we suggest some alternative estimation strategies for the mean parameter based on shrinkage and pretest principles. Generally speaking, the shrinkage and pretest methods use the non-sample information (NSI) regarding that parameter of interest. In practice, NSI is readily available in the form of a realistic conjecture based on the experimenter\u27s knowledge and experience with the problem under consideration. It is advantageous to use NSI in the estimation process to construct improved estimation for the parameter of interest. In this contribution, the large sample properties of the suggested estimators will be assessed, both analytically and numerically. More importantly, a Monte Carlo simulation is conducted to investigate the relative performance of the estimators for moderate and large samples. For illustrative purposes, the proposed methodology is applied to a published data set. © 2011 King Fahd University of Petroleum and Minerals

Molecular features of new Peach Latent Mosaic Viroid variants suggest that recombination may have contributed to the evolution of this infectious RNA.

peer reviewe

Pseudomonas rhizophila S211, a New Plant Growth-Promoting Rhizobacterium with Potential in Pesticide-Bioremediation

A number of Pseudomonas strains function as inoculants for biocontrol, biofertilization, and phytostimulation, avoiding the use of pesticides and chemical fertilizers. Here, we present a new metabolically versatile plant growth-promoting rhizobacterium, Pseudomonas rhizophila S211, isolated from a pesticide contaminated artichoke field that shows biofertilization, biocontrol and bioremediation potentialities. The S211 genome was sequenced, annotated and key genomic elements related to plant growth promotion and biosurfactant (BS) synthesis were elucidated. S211 genome comprises 5,948,515 bp with 60.4% G+C content, 5306 coding genes and 215 RNA genes. The genome sequence analysis confirmed the presence of genes involved in plant-growth promoting and remediation activities such as the synthesis of ACC deaminase, putative dioxygenases, auxin, pyroverdin, exopolysaccharide levan and rhamnolipid BS. BS production by P. rhizophila S211 grown on olive mill wastewater based media was effectively optimized using a central-composite experimental design and response surface methodology (RSM). The optimum conditions for maximum BS production yield (720.80 ± 55.90 mg/L) were: 0.5% (v/v) inoculum size, 15% (v/v) olive oil mill wastewater (OMWW) and 40◦C incubation temperature at pH 6.0 for 8 days incubation period. Biochemical and structural characterization of S211 BS by chromatography and spectroscopy studies suggested the glycolipid nature of the BS. P. rhizophila rhamnolipid was stable over a wide range of temperature (40–90◦C), pH (6–10), and salt concentration (up to 300mM NaCl). Due to its low-cost production, emulsification activities and high performance in solubilization enhancement of chemical pesticides, the indigenous BS-producing PGPR S211 could be used as a promising agent for environmental bioremediation of pesticide-contaminated agricultural soils

The Bursty Star Formation Histories of Low-mass Galaxies at 0.4<z<10.4<z<1 Revealed by Star Formation Rates Measured from Hβ\beta and FUV

We investigate the burstiness of star formation histories (SFHs) of galaxies at $0.4<z<1$ by using the ratio of star formation rates (SFRs) measured from H$\beta$ and FUV (1500 \AA) (H$\beta$--to--FUV ratio). Our sample contains 164 galaxies down to stellar mass (M*) of $10^{8.5} M_\odot$ in the CANDELS GOODS-N region, where Team Keck Redshift Survey DEIMOS spectroscopy and HST/WFC3 F275W images from CANDELS and Hubble Deep UV Legacy Survey are available. When the {\it ratio} of H$\beta$- and FUV-derived SFRs is measured, dust extinction correction is negligible (except for very dusty galaxies) with the Calzetti attenuation curve. The H$\beta$--to--FUV ratio of our sample increases with M* and SFR. The median ratio is $\sim$0.7 at M*$\sim10^{8.5} M_\odot$ (or SFR$\sim 0.5 M_\odot/yr$) and increases to $\sim$1 at M*$\sim10^{10} M_\odot$ (or SFR $\sim 10 M_\odot/yr$). At M*$<10^{9.5} M_\odot$, our median H$\beta$--to--FUV ratio is lower than that of local galaxies at the same M*, implying a redshift evolution. Bursty SFH on a timescale of a few tens of megayears on galactic scales provides a plausible explanation of our results, and the importance of the burstiness increases as M* decreases. Due to sample selection effects, our H$\beta$--to--FUV ratio may be an upper limit of the true value of a complete sample, which strengthens our conclusions. Other models, e.g., non-universal initial mass function or stochastic star formation on star cluster scales, are unable to plausibly explain our results.Comment: 13 pages, 8 figures. ApJ accepted. The main conclusions are not changed. Major modifications include: (1) to be consistent with the literature, now reporting H\beta--to--FUV ratio (rather than FUV--to--H\beta\ in the first version); (2) detailed discussions on dust extinction correction; (3) new SF bustiness calculation; and (4) enriched discussions in Introductio

Molecular Evidence of Tomato Yellow Leaf Curl Virus-Sicily Spreading on Tomato, Pepper and Bean in Tunisia

Unusual symptoms including yellowing, stunting, curling, crumpling and plant size reduction were observed in tomato fields and green houses in Tunisia. These symptoms, generally associated with the Tomato yellow leaf curl virus (TYLCV) complex, have become increasingly common in recent years. In order to ascertain the molecular characteristics of Tunisian isolates by PCR, both the coat protein gene and the intergenic region of eleven isolates were amplified using specific primers, and sequenced. The PCR procedure also allowed the amplification of viral DNA fragments using a bean total DNA as a template. Phylogenetic analysis suggested that these Tunisian isolates clustered with a Sicilian isolate of TYLCSV-Sic. This is the first report of the involvement of this viral species in Phaseolus vulgaris disease

Genome-Wide Association Studies (GWAS) breast cancer susceptibility loci in Arabs: susceptibility and prognostic implications in Tunisians

Genome-wide Association Studies (GWAS) revealed novel genetic markers for breast cancer susceptibility. But little is known about the risk factors and molecular events associated with breast cancer in Arab Population. Therefore, we designed a broad study to investigate the susceptibility and prognostic implications of the GWAS breast cancer loci in the Tunisian population. In a cohort of 640 unrelated patients with breast cancer and 371 healthy control subjects, we characterized the variation of 9 single nucleotide polymorphisms (SNPs), namely rs1219648, rs2981582; rs8051542, rs12443621, and rs3803662; rs889312; rs3817198; rs13387042 and rs13281615. Only 5 out of 9 GWAS breast cancer loci were found to be significantly associated with breast cancer in Tunisians: The rs1219648 (G vs. A allele: OR = 1.36, P = 1 × 10(−3)) and rs2981582 (A vs. G allele: OR = 1.55, P = 3 × 10(−6)) of FGFR2 gene; the rs8051542 of the TNRC9 gene (T vs. C allele: OR = 1.40, P = 4 × 10(−4)); the rs889312 of the MAP3K1 gene (C vs. A allele: OR = 1.33, P = 3 × 10(−3)) and the rs13281615 located on 8q24 (G vs. A allele: OR = 1.21, P = 0.03). Homozygous variant genotypes of rs2981582 were strongly related to lymph node negative breast cancer (OR = 3.33, P = 6 × 10(−7)) and the minor allele of rs2981582 was associated with increased risk of ER+ tumors (OR = 1.57, P = 0.02; OR = 2.15, P = 0.001, for heterozygous and homozygous variant genotypes, respectively) and increased risk of distant metastasis development (OR = 2.30, P = 4 × 10(−3); OR = 3.57, P = 6 × 10(−5), for heterozygous and homozygous variant genotypes, respectively) in a dose dependent manner. The association for rs8051542 was stronger for high-grade SBR tumors (OR = 2.54, P = 2 × 10(−4)). GG genotype of rs13387042 on 2q35 showed a significant association with the risk of developing distant metastasis (OR = 1.94, P = 0.02). The G allele of rs1219648 in FGFR2 and the A allele of rs13387042 on 2q35 indicated a better prognosis by showing a significantly higher overall survival rates (P = 0.013 and P = 0.005, respectively). In conclusion, GWAS breast cancer FGFR2, TNRC9, MAP3K1, and 8q24 loci are associated with an increased risk of breast cancer and genetic variation in FGFR2 gene may predict the aggressiveness of breast cancer in Tunisians. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10549-012-2202-6) contains supplementary material, which is available to authorized users

Symbiotic performance and characterization of Pigeonpea (Cajanus cajan L. Millsp.) Rhizobia occurring in South African soils

Pigeonpea (Cajanus cajan (L.) Millsp.) is an important grain legume, which, like several other legumes, depends on the process of biological nitrogen fixation for its nitrogen (N2 ) requirement by forming a symbiotic association with rhizobia. Compared to other tropical legumes, however, the productivity of pigeonpea in South Africa is low, despite the extensive interests in developing it for wider markets. To assist this process, the objectives of the current study were to (i) characterize putative indigenous rhizobial strains that were previously derived from local soils with no previous history of legume cultivation and (ii) confirm their nodulation abilities on a local landrace and a genetically improved (exotic) genotype of pigeonpea. DNA-based analyses using the 16S rRNA and recA genes showed that the strains predominantly represented Rhizobium and Bradyrhizobium, although we also recovered Phyllobacterium and Paraburkholderia. These rhizobia nodulated both the local landrace and the improved pigeonpea genotype that were included for comparative purposes. In many cases, rhizobia performed similarly on the two genotypes, although the locally sourced landrace mostly performed better in terms of nodulation and plant biomass. While the current study generated vital information regarding the diversity of indigenous rhizobia associating with pigeonpea, further screening (including field inoculation trials) would be necessary to identify possible elite nitrogen-fixing rhizobial strains for development as inoculants to enhance South African pigeonpea production.The University of Venda Research and Publications Committee.The University of Venda Research and Publications CommitteeBiochemistryGenetic