223 research outputs found

    An Extinction Study of the Taurus Dark Cloud Complex

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    We present a study of the detailed distribution of extinction in a region of the Taurus dark cloud complex. Our study uses new BVR images of the region, spectral classification data for 95 stars, and IRAS Sky Survey Atlas (ISSA) 60 and 100 micron images. We study the extinction of the region in four different ways, and we present the first inter-comparison of all these methods, which are: 1) using the color excess of background stars for which spectral types are known; 2) using the ISSA 60 and 100 micron images; 3) using star counts; and 4) using an optical (V and R) version of the average color excess method used by Lada et al. (1994). We find that all four methods give generally similar results, with important exceptions. To study the structure in the dust distribution, we compare the ISSA extinction and the extinction measured for individual stars. From the comparison, we conclude that in the relatively low extinction regions studied, with 0.9 < A_V < 3.0 mag (away from filamentary dark clouds and IRAS cores), there are no fluctuations in the dust column density greater than 45% (at the 99.7% confidence level), on scales smaller than 0.2 pc. We also report the discovery of a previously unknown stellar cluster behind the Taurus dark cloud near R.A 4h19m00s, Dec. 27:30:00 (B1950)Comment: 49 pages (which include 6 pages of tables and 6 pages of figures

    Polymer assembly encapsulation of lanthanide nanoparticles as contrast agents for in vivo micro-CT

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    Despite recent technological advancements in microcomputed tomography (micro-CT) and contrast agent development, pre-clinical contrast agents are still predominantly iodine-based. Higher contrast can be achieved when using elements with higher atomic numbers, such as lanthanides; lanthanides also have x-ray attenuation properties that are ideal for spectral CT. However, the formulation of lanthanide-based contrast agents at the high concentrations required for vascular imaging presents a significant challenge. In this work, we developed an erbium-based contrast agent that meets micro-CT imaging requirements, which include colloidal stability upon redispersion at high concentrations, evasion of rapid renal clearance, and circulation times of tens of minutes in small animals. Through systematic studies with poly(ethylene glycol) (PEG)-poly(propylene glycol), PEG-polycaprolactone, and PEG-poly(l-lactide) (PLA) block copolymers, the amphiphilic block copolymer PEG114-PLA53 was identified to be ideal for encapsulating oleate-coated lanthanide-based nanoparticles for in vivo intravenous administration. We were able to synthesize a contrast agent containing 100 mg/mL of erbium that could be redispersed into colloidally stable nanoparticles in saline after lyophilization. Contrast enhancement of over 250 HU was achieved in the blood pool for up to an hour, thereby meeting the requirements of live animal micro-CT

    Global strategy for the conservation and use of eggplants

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    Common eggplant (Solanum melongena L.), also known as brinjal eggplant or aubergine, is a vegetable crop grown for its large soft fruits which are used in cooking. There are also two African eggplant species grown locally: scarlet eggplant (Solanum aethiop icum L.) and gboma eggplant (Solanum macrocarpon L.). According to the statistics of the United Nations Food and Agriculture Organization (FAO), eggplant is grown on 1.8 million hectares (ha) globally, and 90% of eggplant production takes place in Asia. Breeding and research on eggplant is carried out in many coun tries. Numerous germplasm collections of eggplant and its related species exist to provide plant materials for breeding and related research. In the present study, we overview the current status of eggplant germplasm conservation efforts and the use of eggplant diversity with the aim of providing a forward-looking strategy document. To do this, we surveyed the global databases Genesys and WIEWS (World Information and Early Warning System on Plant Genetic Resources for Food and Agriculture) to obtain information about existing eggplant ex situ collections. The most often represented species in these databases is brinjal eggplant with 12,715 acces sions conserved in total. This is followed by scarlet eggplant (886 accessions) and gboma eggplant (209 accessions). Wild relatives of eggplant are conserved in some collections, but some species are not well represented. In total, 109 eggplant collection holders were iden tified through the database searches. The collection holders were asked to complete an online survey on the status of their collections and the challenges that they faced. Responses were received from 32 collec tion holders, 27 of which provided sufficient data for further analyses. Most of the collection holders that responded were governmental organizations or publicly funded institutions. Two respondents were non-governmental organizations (NGOs). Several challenges related to the sustainability of eggplant conservation and use were identified. Shortages of funds and staff were reported as major threats to collection viability and security by many of the collec tion holders. Opportunities for improvement included recruiting new and/or young people interested in eggplant conservation, and increased collaborations across national borders and among institutions. Improved documentation of existing plant materials and increased information sharing were also identi fied as areas for improvement.publishedVersio

    "Better Safe than Sorry" - Individual Risk-free Pension Schemes in the European Union - Macroeconomic Benefits, the Mobile Working Citizen's Perspective and Why Nots

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    Variations between the diverse pension systems in the member states of the European Union hamper labour market mobility, across country borders but also within the countries of the European Union. From a macroeconomic perspective, and in the light of demographic pressure, this paper argues that allowing individual instead of collective pension building would greatly improve labour market flexibility and thus enhance the functioning of the monetary union. I argue that working citizens would benefit, for three reasons, from pension saving in a risk-free savings account. First, citizens would have a clear picture of the accumulation of their own pension savings throughout their working life. Second, they would pay hardly any extra costs and, third, once retired they would not be subject to the whims of government or other pension fund managers. This paper investigates the feasibility of individual pension building under various parameter settings by calculating the pension saved during a working life and the pension dis-saved after retirement. The findings show that there are no reasons why the European Union and individual member states should not allow individual risk-free pension savings accounts. This would have macroeconomic benefits and provide a solid pension provision that can enhance mobility, instead of engaging workers in different mandatory collective pension schemes that exist around in the European Union

    Dilute gas of ultracold two-level atoms inside a cavity; generalized Dicke model

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    We consider a gas of ultracold two-level atoms confined in a cavity, taking into account for atomic center-of-mass motion and cavity mode variations. We use the generalized Dicke model, and analyze separately the cases of a Gaussian, and a standing wave mode shape. Owing to the interplay between external motional energies of the atoms and internal atomic and field energies, the phase-diagrams exhibit novel features not encountered in the standard Dicke model, such as the existence of first and second order phase transitions between normal and superradiant phases. Due to the quantum description of atomic motion, internal and external atomic degrees of freedom are highly correlated leading to modified normal and superradiant phases.Comment: 10 pages, 7 figure

    Dissecting the impact of environment, season and genotype on blackcurrant fruit quality traits.

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    This work aims to determine the effect of genotype x environment (GxE) interaction that influence blackcurrant (Ribes nigrum) fruit quality. We applied metabolomics-driven analysis on fruits from four cultivars grown in contrasting European-locations over two seasons. By integrating metabolomics and sensory analysis, we also defined specific metabolic signatures associated with consumer acceptance. Our results showed that rainfall is a crucial factor associated with accumulation of delphinidin- and cyanidin-3-O-glucoside, the two mayor blackcurrant pigments meanwhile temperature affects the main organic acid levels which can be decisive for fruit taste. Sensorial analysis showed that increases in terpenoid and acetate ester volatiles were strongly associated with higher appreciation score, while proacacipetalin, a cyanogenic-glycoside, was positively associated to bitter taste. Our results pave the way for the selection of high-quality cultivars and suitable production sites for blackcurrant cultivation.publishedVersio

    The complete nucleotide sequence and genome organization of the M RNA segment of peanut bud necrosis tospovirus and comparison with other tospoviruses

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    The M RNA of peanut bud necrosis tospovirus is 4801 nucleotides in length. It comprised 2 ORFs in an ambisense organization and terminal inverted repeats. The 3 prime large ORF (3363 nucleotides in the virus-complementary strand) encoded a protein with a predicted size of 127.2 kDa which was identified as the glycoprotein precursor (GP) of the G1 and G2 glycoproteins. A comparison of the deduced amino acid sequence of GP revealed 37% identity and 58-59% similarity with that of tomato spotted wilt tospovirus (TSWV,serogroup I) and impatiens necrotic spot tospovirus (INSV, serogroup III) and 21-23% identity and 44-47% similarity with members of the genus Bunyavirus. The 5 prime small ORF (924 nucleotides in the virus-sense strand) encoded a 34.2 kDa protein which was identified as the non-structural (NSm) protein based on 41-43% identity and 60-63% similarity with TSWV and INSV. Defective RNA molecules derived from the genomic M RNA were detected during continuous passage of the virus by sap inoculations

    Peanut bud necrosis tospovirus S RNA: complete nucleotide sequence, genome organization and homology to other tospoviruses.

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    The complete nucleotide sequence of the S RNA of peanut bud necrosis virus (PBNV) has been determined. The RNA is 3 057 nucleotides in length, contains inverted repeats and two open reading frames (ORFs) with an ambisense coding strategy that are separated by an A+U-rich intergenic region. One ORF (1 320 nucleotides in the viral sense strand) encodes a Mr 49.5 kDa protein, identified as the nonstructural (NSs) protein based on similarity to published tospovirus sequences. The second ORF (831 nucleotides in virus complementary strand) encodes a Mr 30.6 kDa protein. This protein was identified as the nucleocapsid (N) protein based on sequence similarities. Amino acid sequence comparison of N and NSs proteins revealed identities of 22-34% with the reported tospovirus isolates of serogroups I, II, and III, whereas it had 82-86% identity with viruses in serogroup IV, watermelon silver mottle virus (WSMV) and tomato isolate of peanut bud necrosis (PBNV-To). Two subgenomic RNA species detected in PBNV infected tissue corresponded to the predicted sizes (1.65 and 1.4 kb) of the NSs and N mRNAs. The data presented show conclusively that PBNV should be included in serogroup IV, along with WSMV and PBNV-To
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