6,159 research outputs found

    The space density of z>4 blazars

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    High redshift blazars are an important class of Active Galactic Nuclei (AGN) that can provide an independent estimate of the supermassive black-hole mass function in high redshift radio-loud AGN without the bias due to absorption along the line-of-sight. Using the Cosmic Lens All Sky Survey (CLASS) we built a complete radio flux-limited sample of high redshift (z>4) blazars suitable for statistical studies. By combining dedicated optical observations and the SDSS spectroscopic database, we obtained a sample of 26 blazar candidates with a spectroscopic redshift above 4. On the basis of their radio spectrum we distinguish between blazars and QSO with a Gigahertz Peaked Spectrum (GPS) like spectrum. Out of the 18 confirmed blazars 14 constitute a completely identified, flux-limited sample down to a magnitude of 21 (AB). Using this complete sample we derive a space density of blazars with 4<z<5.5 of rho=0.13 (+0.05,-0.03) Gpc^-3. This is the first actual estimate of the blazar space density in this range of redshift. This value is in good agreement with the extrapolation of the luminosity function and cosmological evolution based on a sample of flat-spectrum radio quasars selected at lower redshifts and it is consistent with a cosmological evolution peaking at z∌\sim2 similar to radio-quiet QSO. We do not confirm, instead, the presence of a peak at z~4 in the space density evolution, recently suggested using an X-ray selected sample of blazars. It is possible that this extreme peak of the evolution is present only among the most luminous blazars.Comment: 14 pages, accepted for publication on MNRAS (https://doi.org/10.1093/mnras/sty3526

    Adaptive potential of hybridization among malaria vectors: Introgression at the immune locus TEP1 between Anopheles coluzzii and A. gambiae in 'Far-West' Africa

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    “Far-West” Africa is known to be a secondary contact zone between the two major malaria vectors Anopheles coluzzii and A. gambiae.We investigated gene-flow and potentially adaptive introgression between these species along a west-to-east transect in Guinea Bissau, the putative core of this hybrid zone. To evaluate the extent and direction of gene flow, we genotyped site 702 in Intron-1 of the para Voltage-Gated SodiumChannel gene, a species-diagnostic nucleotide position throughout most of A. coluzzii and A. gambiae sympatric range. We also analyzed polymorphismin the thioester-binding domain (TED) of the innate immunity-linked thioester-containing protein 1 (TEP1) to investigate whether elevated hybridization might facilitate the exchange of variants linked to adaptive immunity and Plasmodium refractoriness. Our results confirm asymmetric introgression of genetic material from A. coluzzii to A. gambiae and disruption of linkage between the centromeric "genomic islands" of inter-specific divergence. We report that A. gambiae from the Guinean hybrid zone possesses an introgressed TEP1 resistant allelic class, found exclusively in A. coluzzii elsewhere and apparently swept to fixation inWest Africa (i.e. Mali and Burkina Faso). However, no detectable fixation of this allele was found in Guinea Bissau, which may suggest that ecological pressures driving segregation between the two species in larval habitats in this region may be different from those experienced in northern and more arid parts of the species’ range. Finally, our results also suggest a genetic subdivision between coastal and inland A. gambiae Guinean populations and provide clues on the importance of ecological factors in intra-specific differentiation processes

    The value and significance of corporate community relations: an Italian SME perspective

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    Purpose – This paper investigates the link between community of place and small and medium-sized enterprises (SMEs) in Lombard industrial districts in Italy. Design/methodology/approach – A brief literature review of international authors from the stakeholder approach and Corporate Community Relations field is presented. This paper refers to a survey of Lombard industrial districts conducted by ALTIS. The data was collected via a telephone survey from 834 firms. Findings – The main finding is that managing Corporate Community Relations (CCR) is of major importance for company success. The results of the survey show that there are some tools and actions that Italian industrial district SMEs uses to interact with their particular communities of place to develop effective and coherent relationships with their stakeholder groups. Moreover, although the survey shows that though SMEs do implement different CCR activities, they are not able to communicate these effectively through systematic communication strategies. However, the narrow sample includes only a sample of some Lombard districts. Nonetheless, the findings indicate that effective CCR seems to confer competitive advantage based on stakeholder responses and rewards sought. Research limitations/implications – The framework could assist in supporting CCR developments between industrial districts as various players would know how to improve CCR activities. One further suggestion is that University and Research Centres could have a role to play in creating and communicating codified knowledge concerning community relations in industrial districts, while other public players still have to develop specific tasks in improving infrastructures. Originality/value – This study is in line with the main focus of CCR, which is in striving to meet stakeholder and societal needs. However, industrial district SMEs have to learn how to communicate their CCR activities from the examples set by large Italian companies. The paper links the notion of CCR with tools and actions to develop meaningful relationships with both community of place and interest. Moreover, considering the survey results, a new framework for local player roles is proposed

    A newborn with partial pure trisomy of chromosome 7q inherited from paternal balanced translocation with congenital anomalies. a mini review

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    We report on a familial translocation t(3;7)(3q29::7q22) leading to pure trisomy 7q22 --> 7qter in a 21-days-old boy: 46,XY,der(3;7)(3pter--> 3q29::7q22--> 7pter). By conventional citogenetic techniques including fluorescence in situ hybridization (FISH) analysis, the patient was found to have inherited a derivative chromosome 3 from his father: 46,XY,t(3;7)(3pter--> 3q29::7q22--> 7qter;7pter--> 7q22). As a consequence, pure duplications of chromosome 7q have been classified in 4 groups on the basis of the involved region. The present case is included in group 2 which involves large duplications spanning from proximal bands to telomere duplication. In the literature, only one case with a pure duplication of the same region has been described. Despite this, the phenotype is different. Moreover, our patient shares some phenotypic features, such as wide fontanelle, retrognathia, epicathal fold, hypertelorism, pulmonary hypoventilation and early postnatal death. However, the absence of physical characterization in most of the reported cases could justify the lacking phenotype-genotype correlation in patients with partial 7q duplication. Further studies using recent molecular approaches such as array-CGH might permit a more clinically useful grouping of 7q duplications.Fil: Siewert, Susana Elfrida. Universidad Nacional de San Luis. Facultad de QuĂ­mica, BioquĂ­mica y Farmacia. Departamento de BioquĂ­mica y Ciencias BiolĂłgicas; ArgentinaFil: Della Vedova, Maria Cecilia. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - San Luis. Instituto de QuĂ­mica de San Luis. Universidad Nacional de San Luis. Facultad de QuĂ­mica, BioquĂ­mica y Farmacia. Instituto de QuĂ­mica de San Luis; ArgentinaFil: Guillamondegui, M. J.. Provincia de Mendoza. Hospital PediĂĄtrico Dr. Humberto J. Notti; ArgentinaFil: Drut, M.. Laboratorio Privado; ArgentinaFil: Brezigar A.. Provincia de San Luis. Clinic Cerhu; ArgentinaFil: Cardetti, M.. Provincia de San Luis. Clinic Cerhu; ArgentinaFil: MarsĂĄ, S.M.. Laboratorio Genes; Argentin

    Supersolar Ni/Fe production in the Type IIP SN 2012ec

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    SN 2012ec is a Type IIP supernova (SN) with a progenitor detection and comprehensive photospheric-phase observational coverage. Here, we present Very Large Telescope and PESSTO observations of this SN in the nebular phase. We model the nebular [O I] 6300, 6364 lines and find their strength to suggest a progenitor main-sequence mass of 13-15 Msun. SN 2012ec is unique among hydrogen-rich SNe in showing a distinct and unblended line of stable nickel [Ni II] 7378. This line is produced by 58Ni, a nuclear burning ash whose abundance is a sensitive tracer of explosive burning conditions. Using spectral synthesis modelling, we use the relative strengths of [Ni II] 7378 and [Fe II] 7155 (the progenitor of which is 56Ni) to derive a Ni/Fe production ratio of 0.20pm0.07 (by mass), which is a factor 3.4pm1.2 times the solar value. High production of stable nickel is confirmed by a strong [Ni II] 1.939 micron line. This is the third reported case of a core-collapse supernova producing a Ni/Fe ratio far above the solar value, which has implications for core-collapse explosion theory and galactic chemical evolution models.Comment: Published versio

    Chromosomal plasticity and evolutionary potential in the malaria vector Anopheles gambiae sensu stricto: insights from three decades of rare paracentric inversions

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    Background: In the Anopheles gambiae complex, paracentric chromosomal inversions are nonrandomly distributed along the complement: 18/31 (58%) of common polymorphic inversions are on chromosome arm 2R, which represents only ~30% of the complement. Moreover, in An.gambiae sensu stricto, 6/7 common polymorphic inversions occur on 2R. Most of these inversions are considered markers of ecological adaptation that increase the fitness of the carriers of alternative karyotypes in contrasting habitats. However, little is known about the evolutionary forces responsible for their origin and subsequent establishment in field populations. Results: Here, we present data on 82 previously undescribed rare chromosomal inversions (RCIs) recorded during extensive field sampling in 16 African countries over a 30 year period, which may shed light on the dynamics of chromosomal plasticity in An. gambiae. We analyzed breakpoint distribution, length, and geographic distribution of RCIs, and compared these measures to those of the common inversions. We found that RCIs, like common inversions, are disproportionately clustered on 2R, which may indicate that this arm is especially prone to breakages. However, contrasting patterns were observed between the geographic distribution of common inversions and RCIs. RCIs were equally frequent across biomes and on both sides of the Great Rift Valley (GRV), whereas common inversions predominated in arid ecological settings and west of the GRV. Moreover, the distribution of RCI lengths followed a random pattern while common inversions were significantly less frequent at shorter lengths. Conclusion: Because 17/82 (21%) RCIs were found repeatedly at very low frequencies – at the same sampling location in different years and/or in different sampling locations – we suggest that BMC Evolutionary Biology 2008, 8:309 http://www.biomedcentral.com/1471-2148/8/309 RCIs are subject mainly to drift under unperturbed ecological conditions. Nevertheless, RCIs may represent an important reservoir of genetic variation for An. gambiae in response to environmental changes, further testifying to the considerable evolutionary potential hidden within this pan-African malaria vector

    Distribution of knock-down resistance mutations in Anopheles gambiae molecular forms in west and west-central Africa

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    <p>Abstract</p> <p>Background</p> <p><it>Knock-down </it>resistance (<it>kdr</it>) to DDT and pyrethroids in the major Afrotropical vector species, <it>Anopheles gambiae </it>sensu stricto, is associated with two alternative point mutations at amino acid position 1014 of the voltage-gated sodium channel gene, resulting in either a leucine-phenylalanine (L1014F), or a leucine-serine (L1014S) substitution. In <it>An. gambiae </it>S-form populations, the former mutation appears to be widespread in west Africa and has been recently reported from Uganda, while the latter, originally recorded in Kenya, has been recently found in Gabon, Cameroon and Equatorial Guinea. In M-form populations surveyed to date, only the L1014F mutation has been found, although less widespread and at lower frequencies than in sympatric S-form populations.</p> <p>Methods</p> <p><it>Anopheles gambiae </it>M- and S-form specimens from 19 sites from 11 west and west-central African countries were identified to molecular form and genotyped at the <it>kdr </it>locus either by Hot Oligonucleotide Ligation Assay (HOLA) or allele-specific PCR (AS-PCR).</p> <p>Results</p> <p>The <it>kdr </it>genotype was determined for about 1,000 <it>An. gambiae </it>specimens. The L1014F allele was found at frequencies ranging from 6% to 100% in all S-form samples (N = 628), with the exception of two samples from Angola, where it was absent, and coexisted with the L1014S allele in samples from Cameroon, Gabon and north-western Angola. The L1014F allele was present in M-form samples (N = 354) from Benin, Nigeria, and Cameroon, where both M- and S-forms were sympatric.</p> <p>Conclusion</p> <p>The results represent the most comprehensive effort to analyse the overall distribution of the L1014F and L1014S mutations in <it>An. gambiae </it>molecular forms, and will serve as baseline data for resistance monitoring. The overall picture shows that the emergence and spread of <it>kdr </it>alleles in <it>An. gambiae </it>is a dynamic process and that there is marked intra- and inter-form heterogeneity in resistance allele frequencies. Further studies are needed to determine: i) the importance of selection pressure exerted by both agricultural and public health use of pyrethroid insecticides, ii) the phenotypic effects, particularly when the two mutations co-occur; and iii) the epidemiological importance of <it>kdr </it>for both pyrethroid- and DDT-based malaria control operations, particularly if/when the two insecticides are to be used in concert.</p

    Satellite and ground atmospheric particulate matter detection over Tucuman city, Argentina, space-time distribution, climatic and seasonal variability

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    The analysis of atmospheric particles (aerosols) is of special interest due to their potential effects on human health and other applications. In this paper the climatic and seasonal effects on aerosols have been characterized in TucumĂĄn city (26°50’ S, 65° 13’ W,450 masl),Argentina, for the 2006–2013 period. The atmospheric aerosols in TucumĂĄn city result from both stationary and mobile sources such as: industrial activity of sugar cane and alcohol distilleries, paper industry, biomass burning (mainly sugarcane waste crop and grasslands), household waste burning and transport emissions. The peak of industrial activity is seasonal, coincident with the austral winter (July-August-September), when accumulation of particles in the lower atmosphere occurs. In this region, there are no studies like the present one that evaluate, using “in situ” equipment, the temporal variation of aerosols and its causes, by applying modern analytical techniques. A continuous volumetric and isokinetic sampler of Hirst type (Burkard), was used for atmospheric particle sampling, in weekly records between 2006 and 2013. The particle concentration (number of particles per cubic meter) showed an increasing trend in the studied period. The monthly variation of: the particle concentration; the aerosol optical thickness at a wavelength of 550 nm (AOD550) obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors onboard Aqua (NASA) satellite, and the AOD from different aerosol tracers (black and organic carbon, sea salt, sulfates, dust) obtained from the Modern-Era Retrospective Analysis for Research and Applications (MERRA-2), were also analyzed. The temporal variation in particle concentration was explained mostly by wind direction, while the corresponding variation for AOD550(MODIS) was explained by temperature and seasonality (as by-product of climatic variation and anthropogenic particle emission sources). The variation in the AOD550(MERRA-2) data series were explained by temperature, humidity, precipitation, and seasonality, with less effect of wind speed and direction. Particle concentration, AOD550(MODIS), and AOD550(MERRA-2) were highly variable. The cross-correlation between AOD550(MODIS) and AOD550(MERRA-2) time series was significantly positive at lag zero. Other contribution was the determination of the space-time distribution of aerosols on a monthly basis considering AOD550 MODIS (3 km × 3 km) data. The present study suggests that these variables are affected by temperature and wind dynamics driven by seasonal and high-order autoregressive non-linear processes.Fil: GarcĂ­a, MarĂ­a E.. Laboratorio de PalinologĂ­a; ArgentinaFil: Della Ceca, Lara Sofia. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - Rosario. Instituto de FĂ­sica de Rosario. Universidad Nacional de Rosario. Instituto de FĂ­sica de Rosario; ArgentinaFil: Micheletti, Maria Isabel. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - Rosario. Instituto de FĂ­sica de Rosario. Universidad Nacional de Rosario. Instituto de FĂ­sica de Rosario; ArgentinaFil: Piacentini, Ruben Dario Narciso. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂ­micas y FarmacĂ©uticas; Argentina. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - Rosario. Instituto de FĂ­sica de Rosario. Universidad Nacional de Rosario. Instituto de FĂ­sica de Rosario; ArgentinaFil: Ordano, Mariano AndrĂ©s. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico - TucumĂĄn. Unidad Ejecutora Lillo; ArgentinaFil: Reyes, Nora J. F.. FundaciĂłn Miguel Lillo; ArgentinaFil: Buedo, SebastiĂĄn. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico - TucumĂĄn. Unidad Ejecutora Lillo; ArgentinaFil: GonzĂĄlez, Juan A.. FundaciĂłn Miguel Lillo; Argentin

    A Pharmacogenetic Approach to Identify Mutant Forms of α-Galactosidase A that Respond to a Pharmacological Chaperone for Fabry Disease

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    Fabry disease is caused by mutations in the gene (GLA) that encodes α-galactosidase A (α-Gal A). The iminosugar AT1001 (GR181413A, migalastat hydrochloride, 1-deoxygalactonojirimycin) is a pharmacological chaperone that selectively binds and stabilizes α-Gal A, increasing total cellular levels and activity for some mutant forms (defined as “responsive”). In this study, we developed a cell-based assay in cultured HEK-293 cells to identify mutant forms of α-Gal A that are responsive to AT1001. Concentration-dependent increases in α-Gal A activity in response to AT1001 were shown for 49 (60%) of 81 mutant forms. The responses of α-Gal A mutant forms were generally consistent with the responses observed in male Fabry patient-derived lymphoblasts. Importantly, the HEK-293 cell responses of 19 α-Gal A mutant forms to a clinically achievable concentration of AT1001 (10 ”M) were generally consistent with observed increases in α-Gal A activity in peripheral blood mononuclear cells from male Fabry patients orally administered AT1001 during Phase 2 clinical studies. This indicates that the cell-based responses can identify mutant forms of α-Gal A that are likely to respond to AT1001 in vivo. Thus, the HEK-293 cell-based assay may be a useful aid in the identification of Fabry patients with AT1001-responsive mutant forms. Hum Mutat 32:1–13, 2011. © 2011 Wiley-Liss, Inc
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