Search, matching, and self-organization of a marketplace

In many developing countries, clusters of small shops are the typical market-place. We investigate an economic model in which, between buyers and sellers in a marketplace, a circular causality including the search process produces agglomeration forces, given the initial location of the marketplace location exogenously in a linear city. We conclude that initial number of buyers and sellers is important in forming a large marketplace

Heterogeneous firms and cost sharing in China\u27s marketplaces

This study extends Melitz\u27s model with heterogeneous firms by introducing shared fixed costs in a marketplace. It aims to explain heterogeneous firms\u27 choice between traditional marketplaces and modern distribution channels on the basis of their productivities. The results reveal that the co-existence of a traditional marketplace and modern distribution channels improves social welfare. In addition, a deregulation policy for firm entry outside a marketplace and accumulation of human capital are factors that contribute to improve the social welfare

Presence of qnr gene in Escherichia coli and Klebsiella pneumoniae resistant to ciprofloxacin isolated from pediatric patients in China

<p>Abstract</p> <p>Background</p> <p>Quinolone resistance in <it>Enterobacteriaceae </it>results mainly from mutations in type II DNA topoisomerase genes and/or changes in the expression of outer membrane and efflux pumps. Several recent studies have indicated that plasmid-mediated resistance mechanisms also play a significant role in fluoroquinolone resistance, and its prevalence is increasing worldwide. In China, the presence of the <it>qnr </it>gene in the clinical isolates of <it>Enterobacteriaceae </it>has been reported, but this transmissible quinolone resistance gene has not been detected in strains isolated singly from pediatric patients. Because quinolones associated with a variety of adverse side effects on children, they are not authorized for pediatric use. This study therefore aimed to investigate the presence of the <it>qnr </it>gene in clinical isolates of <it>E. coli </it>and <it>K. pneumoniae </it>from pediatric patients in China.</p> <p>Methods</p> <p>A total 213 of non-repetitive clinical isolates resistant to ciprofloxacin from <it>E. coli </it>and <it>K. pneumoniae </it>were collected from hospitalized patients at five children's hospital in Beijing, Shanghai, Guangzhou, and Chongqing. The isolates were screened for the plasmid-mediated quinolone resistance genes of <it>qnrA</it>, <it>qnrB</it>, and <it>qnrS </it>by PCR. Transferability was examined by conjugation with the sodium azide-resistant <it>E. coli </it>J53. All <it>qnr</it>-positive were analyzed for clonality by enterobacterial repetitive intergenic consensus (ERIC)-PCR.</p> <p>Results</p> <p>The study found that 19 ciprofloxacin-resistant clinical isolates of <it>E. coli </it>and <it>K. pneumoniae </it>were positive for the <it>qnr </it>gene, and most of the <it>qnr </it>positive strains were ESBL producers. Conjugation experiments showed that quinolone resitance could be transferred to recipients. Apart from this, different DNA banding patterns were obtained by ERIC-PCR from positive strains, which means that most of them were not clonally related.</p> <p>Conclusion</p> <p>This report on transferable fluoroquinolone resistance due to the <it>qnr </it>gene among <it>E. coli </it>and <it>K. pneumoniae </it>strains indicated that plasmid-mediated quinolone resistance has emerged in pediatric patients in China.</p

Molecular Characterization of a Fus3/Kss1 Type MAPK from Puccinia striiformis f. sp. tritici, PsMAPK1

Puccinia striiformis f. sp. tritici (Pst) is an obligate biotrophic fungus that causes the destructive wheat stripe rust disease worldwide. Due to the lack of reliable transformation and gene disruption method, knowledge about the function of Pst genes involved in pathogenesis is limited. Mitogen-activated protein kinase (MAPK) genes have been shown in a number of plant pathogenic fungi to play critical roles in regulating various infection processes. In the present study, we identified and characterized the first MAPK gene PsMAPK1 in Pst. Phylogenetic analysis indicated that PsMAPK1 is a YERK1 MAP kinase belonging to the Fus3/Kss1 class. Single nucleotide polymerphisms (SNPs) and insertion/deletion were detected in the coding region of PsMAPK1 among six Pst isolates. Real-time RT-PCR analyses revealed that PsMAPK1 expression was induced at early infection stages and peaked during haustorium formation. When expressed in Fusarium graminearum, PsMAPK1 partially rescued the map1 mutant in vegetative growth and pathogenicity. It also partially complemented the defects of the Magnaporthe oryzae pmk1 mutant in appressorium formation and plant infection. These results suggest that F. graminearum and M. oryzae can be used as surrogate systems for functional analysis of well-conserved Pst genes and PsMAPK1 may play a role in the regulation of plant penetration and infectious growth in Pst

Chelifera tibetensis Wang, Yan & Yang, 2014, sp. nov.

&lt;i&gt;Chelifera tibetensis&lt;/i&gt; sp. nov. &lt;p&gt;Figs 4&ndash;6&lt;/p&gt; &lt;p&gt; &lt;b&gt;Diagnosis.&lt;/b&gt; Antenna entirely dark yellow. Wing entirely hyaline, without pterostigma. Male cercus much wider than epandrium, with wide apical margin nearly truncate in lateral view. Epandrium distinctly longer than cercus, apically long and finger-like. Postgonite long and band-like, with curved apex.&lt;/p&gt; &lt;p&gt; &lt;b&gt;Description.&lt;/b&gt; Male. Body length 3.3 mm, wing length 4.1 mm.&lt;/p&gt; &lt;p&gt;Head black with pale gray pollinosity. Setulae on head pale yellow, setae brownish yellow; postocular setae very short and hair-like; 1 long and strong vt; ocellar tubercle weak with 2 long oc and 2 very short posterior setulae. Antenna entirely dark yellow; pedicel with circlet of pale yellow apical setulae; first flagellomere long and conical (2 times longer than wide), minutely pubescent; arista spine-like, about 0.33 as long as first flagellomere, bare. Proboscis dark yellow with blackish setulae; palpus dark yellow with short blackish setulae.&lt;/p&gt; &lt;p&gt;Thorax dark brownish with pale gray pollinosity, except postalar calli dark yellow. Setulae on thorax pale yellow, setae brownish yellow; 1 long sa and psa subequal in length; scutellum with 3 pairs of sc (only 2 apical sc long). Legs yellow, except tarsomeres 3&ndash;5 brown. Setulae and setae on legs blackish. Fore femur greatly thickened, 2.7 times as thick as mid femur, with 2 rows of black ventral denticles and 2 rows of strong outer ventral setae brownish yellow (6 av, 5 pv, with 1 basalmost pv longest, nearly as long as thickness of fore femur); fore tibia distinctly shorter than fore femur (0.7 times as long as fore femur), with blackish ventral ridge and 1 black strong apicoventral seta. Fore and hind tibiae each with short dense brown ventral setae on apical margin arranged in comb; mid tibia without additional ventral denticles and setae. Wing hyaline, without pterostigma; veins brownish yellow. Squama yellow with pale yellow setulae. Halter yellow.&lt;/p&gt; &lt;p&gt;Abdomen dark brown with pale gray pollinosity, with hypopygium dark yellow except cerci with dark brown margin. Setulae on abdomen pale yellow.&lt;/p&gt; &lt;p&gt;Male genitalia (Figs 4&ndash;6): Cercus large and wide, much wider than epandrium at widest point in lateral view, with wide apical margin nearly truncate in lateral view. Epandrium distinctly longer than cercus; basally rather wide, narrowed toward tip, apically long finger-like. Hypandrium slightly wider than epandrium, long subconical in lateral view; hypandrial process short finger-like. Postgonite long band-like with curved apex. Phallus strongly curved upward, with broad apex distinctly curved and bearing group of spines.&lt;/p&gt; &lt;p&gt;Female. Unknown.&lt;/p&gt; &lt;p&gt; &lt;b&gt;Type material.&lt;/b&gt; HOLOTYPE &male;, CHINA, Tibet, Bomi (N29&deg;51&prime; 42.57&Prime; E95&deg;46&prime; 1.59&Prime;), Galonglashan, 1500 m, 13.VII.2013, X. Liu (CAU).&lt;/p&gt; &lt;p&gt; &lt;b&gt;Distribution.&lt;/b&gt; China (Tibet).&lt;/p&gt; &lt;p&gt; &lt;b&gt;Etymology.&lt;/b&gt; This specific name refers to the type locality, Tibet.&lt;/p&gt;Published as part of &lt;i&gt;Wang, Xiwei, Yan, Shanchun &amp; Yang, Ding, 2014, Two new species of Chelifera Macquart from China (Diptera: Empididae), pp. 187-192 in Zootaxa 3795 (2)&lt;/i&gt; on pages 190-191, DOI: 10.11646/zootaxa.3795.2.8, &lt;a href="http://zenodo.org/record/225657"&gt;http://zenodo.org/record/225657&lt;/a&gt

Chelifera liuae Wang, Yan & Yang, 2014, sp. nov.

&lt;i&gt;Chelifera liuae&lt;/i&gt; sp. nov. &lt;p&gt;Figs 1&ndash;3&lt;/p&gt; &lt;p&gt; &lt;b&gt;Diagnosis.&lt;/b&gt; Thorax yellow except dorsum mainly black. Antenna entirely dark yellow. Pterostigma short and wide, filling apex of cell r1. Male cercus apically bifurcated into small acute dorsal process and large obtuse ventral process. Epandrium subtriangular apically. Postgonite long thin with two apical hooks.&lt;/p&gt; &lt;p&gt; &lt;b&gt;Description.&lt;/b&gt; Male. Body length 4.2&ndash;4.6 mm, wing length 4.2&ndash;4.3 mm.&lt;/p&gt; &lt;p&gt;Head black with pale gray pollinosity. Setulae on head pale yellow, setae brownish yellow; postocular setae very short and hair-like; 1 long and strong vt; ocellar tubercle weak with 2 long oc and 2 very short posterior setulae. Antenna entirely dark yellow; pedicel with circlet of pale yellow apical setulae; first flagellomere long and conical (1.9 times longer than wide), minutely pubescent; arista spine-like, about 0.33 as long as first flagellomere, bare. Proboscis dark yellow with blackish setulae; palpus dark yellow with short blackish setulae.&lt;/p&gt; &lt;p&gt;Thorax yellow with pale gray pollinosity, except pronotum black with yellow lateral portion; mesoscutum black with yellow lateral portion, black lateral spot just anterior to wing base and posterior margin brownish yellow; scutellum and postnotum black. Setulae on thorax pale yellow, setae brownish yellow; 1 long sa and psa subequal in length; scutellum with 3 pairs of sc (only 2 apical sc long). Legs yellow except fore tarsomeres 4&ndash;5, entire mid tarsus, apex of hind tarsomere 3 and hind tarsomeres 4&ndash;5 brown. Setulae and setae on legs blackish. Fore femur greatly thickened, 2.4&ndash;2.5 times as wide as mid femur, with 2 rows of black ventral denticles and 2 rows of strong outer ventral setae brownish yellow (6&ndash;7 av, 5&ndash;6 pv, with 1 basalmost pv longest, nearly as long as thickness of fore femur); fore tibia distinctly shorter than fore femur (0.7 times as long as fore femur), with blackish ventral ridge and 1 black strong apicoventral seta. Fore and hind tibiae each with short dense brown ventral setae on apical margin arranged in comb, mid tibia without additional ventral denticles and setae. Wing hyaline, dark brown pterostigma short wide and filling apex of cell r1; veins brownish to brown. Squama yellow with pale yellow setulae. Halter yellow.&lt;/p&gt; &lt;p&gt;Abdomen dark yellow with pale gray pollinosity, except tergites 1&ndash;7 dark brown and hypopygium black. Setulae on abdomen pale yellow.&lt;/p&gt; &lt;p&gt;Male genitalia (Figs 1&ndash;3): Cercus large and wide, wider than epandrium at widest point in lateral view, apically furcated into small acute dorsal process and large obtuse ventral process. Epandrium slightly shorter than cercus; basally rather narrow, medially wide, apically somewhat narrowed and subtriangular. Hypandrium nearly as wide as epandrium, nearly quadrate in lateral view; hypandrial process short finger-like. Postgonite long and thin with two apical hooks. Phallus strongly curved upwards, with broad apex bearing group of spines.&lt;/p&gt; &lt;p&gt;Female. Unknown.&lt;/p&gt; &lt;p&gt; &lt;b&gt;Type material.&lt;/b&gt; HOLOTYPE &male;, CHINA, Sichuan, Xiaojin (N31&deg;0&prime; 4.67&Prime; E102&deg;21&prime; 45.41&Prime;), Balangshan, 3281 m, 9.VIII.2013, X. Liu (CAU). PARATYPES: 2 &male;, same data as holotype (CAU).&lt;/p&gt; &lt;p&gt; &lt;b&gt;Distribution.&lt;/b&gt; China (Sichuan).&lt;/p&gt; &lt;p&gt; &lt;b&gt;Etymology.&lt;/b&gt; This specific name refers to collector of the type specimens, Dr. Xiaoyan Liu.&lt;/p&gt;Published as part of &lt;i&gt;Wang, Xiwei, Yan, Shanchun &amp; Yang, Ding, 2014, Two new species of Chelifera Macquart from China (Diptera: Empididae), pp. 187-192 in Zootaxa 3795 (2)&lt;/i&gt; on pages 188-189, DOI: 10.11646/zootaxa.3795.2.8, &lt;a href="http://zenodo.org/record/225657"&gt;http://zenodo.org/record/225657&lt;/a&gt