73 research outputs found
Stellar population synthesis models between 2.5 and 5 {\mu}m based on the empirical IRTF stellar library
We present the first single-burst stellar population models in the infrared
wavelength range between 2.5 and 5 {\mu}m which are exclusively based on
empirical stellar spectra. Our models take as input 180 spectra from the
stellar IRTF (Infrared Telescope Facility) library. Our final single-burst
stellar population models are calculated based on two different sets of
isochrones and various types of initial mass functions of different slopes,
ages larger than 1 Gyr and metallicities between [Fe/H] = -0.70 and 0.26. They
are made available online to the scientific community on the MILES web page. We
analyse the behaviour of the Spitzer [3.6]-[4.5] colour calculated from our
single stellar population models and find only slight dependences on both
metallicity and age. When comparing to the colours of observed early-type
galaxies, we find a good agreement for older, more massive galaxies that
resemble a single-burst population. Younger, less massive and more metal-poor
galaxies show redder colours with respect to our models. This mismatch can be
explained by a more extended star formation history of these galaxies which
includes a metal-poor or/and young population. Moreover, the colours derived
from our models agree very well with most other models available in this
wavelength range. We confirm that the mass-to-light ratio determined in the
Spitzer [3.6] {\mu}m band changes much less as a function of both age and
metallicity than in the optical bands.Comment: 25 pages, 19 figures, published in MNRAS, models can be downloaded
from http://miles.iac.e
MILES extended: Stellar population synthesis models from the optical to the infrared
We present the first single-burst stellar population models which covers the
optical and the infrared wavelength range between 3500 and 50000 Angstrom and
which are exclusively based on empirical stellar spectra. To obtain these joint
models, we combined the extended MILES models in the optical with our new
infrared models that are based on the IRTF (Infrared Telescope Facility)
library. The latter are available only for a limited range in terms of both age
and metallicity. Our combined single-burst stellar population models were
calculated for ages larger than 1 Gyr, for metallicities between [Fe/H] = -0.40
and 0.26, for initial mass functions of various types and slopes, and on the
basis of two different sets of isochrones. They are available to the scientific
community on the MILES web page. We checked the internal consistency of our
models and compared their colour predictions to those of other models that are
available in the literature. Optical and near infrared colours that are
measured from our models are found to reproduce the colours well that were
observed for various samples of early-type galaxies. Our models will enable a
detailed analysis of the stellar populations of observed galaxies.Comment: 9 pages, 10 figures, published in A&
The puzzling interpretation of NIR indices: The case of NaI2.21
We present a detailed study of the Na I line strength index centered in the
-band at , {\AA} (NaI2.21 hereafter) relying on different samples of
early-type galaxies. Consistent with previous studies, we find that the
observed line strength indices cannot be fit by state-of-art scaled-solar
stellar population models, even using our newly developed models in the NIR.
The models clearly underestimate the large NaI2.21 values measured for most
early-type galaxies. However, we develop a Na-enhanced version of our newly
developed models in the NIR, which - together with the effect of a bottom-heavy
initial mass function - yield NaI2.21 indices in the range of the observations.
Therefore, we suggest a scenario in which the combined effect of [Na/Fe]
enhancement and a bottom-heavy initial mass function are mainly responsible for
the large NaI2.21 indices observed for most early-type galaxies. To a smaller
extent, also [C/Fe] enhancement might contribute to the large observed NaI2.21
values.Comment: 13 pages, 4 figures, accepted for publication in MNRA
Towards indicative baseline and decarbonization pathways for embodied life cycle GHG emissions of buildings across Europe
Comparison of the greenhouse gas emissions of a high-rise residential building assessed with different national LCA approaches – IEA EBC Annex 72
Introduction: The international research project IEA EBC Annex 72 investigates the life cycle related environmental impacts caused by buildings. The project aims inter alia to harmonise LCA approaches on buildings. Methods: To identify major commonalities and discrepancies among national LCA approaches, reference buildings were defined to present and compare the national approaches. A residential high-rise building located in Tianjin, China, was selected as one of the reference buildings. The main construction elements are reinforced concrete shear walls, beams and floor slabs. The building has an energy reference area of 4566 m2 and an operational heating energy demand of 250 MJ/m2a. An expert team provided information on the quantities of building materials and elements required for the construction, established a BIM model and quantified the operational energy demand. Results: The greenhouse gas emissions and environmental impacts of the building were quantified using 17 country-specific national assessment methods and LCA databases. Comparisons of the results are shown on the level of building elements as well as the complete life cycle of the building. Conclusions: The results of these assessments show that the main differences lie in the LCA background data used, the scope of the assessment and the reference study period applied. Despite the variability in the greenhouse gas emissions determined with the 17 national methods, the individual results are relevant in the respective national context of the method, data, tool and benchmark used. It is important that environmental benchmarks correspond to the particular LCA approach and database of a country in which the benchmark is applied. Furthermore, the results imply to include building technologies as their contribution to the overall environmental impacts is not negligible. Grant support: The authors thank the IEA for its organizational support and the funding organizations in the participating countries for their financial support.IEA -International Energy Agency(undefined
Southeast Asian diversity: first insights into the complex mtDNA structure of Laos
<p>Abstract</p> <p>Background</p> <p>Vast migrations and subsequent assimilation processes have shaped the genetic composition of Southeast Asia, an area of close contact between several major ethnic groups. To better characterize the genetic variation of this region, we analyzed the entire mtDNA control region of 214 unrelated donors from Laos according to highest forensic quality standards. To detail the phylogeny, we inspected selected SNPs from the mtDNA coding region. For <it>a posteriori </it>data quality control, quasi-median network constructions and autosomal STR typing were performed. In order to describe the mtDNA setup of Laos more thoroughly, the data were subjected to population genetic comparisons with 16 East Asian groups.</p> <p>Results</p> <p>The Laos sample exhibited ample mtDNA diversity, reflecting the huge number of ethnic groups listed. We found several new, so far undescribed mtDNA lineages in this dataset and surrounding populations. The Laos population was characteristic in terms of haplotype composition and genetic structure, however, genetic comparisons with other Southeast Asian populations revealed limited, but significant genetic differentiation. Notable differences in the maternal relationship to the major indigenous Southeast Asian ethnolinguistic groups were detected.</p> <p>Conclusions</p> <p>In this study, we portray the great mtDNA variety of Laos for the first time. Our findings will contribute to clarify the migration history of the region. They encourage setting up regional and subpopulation databases, especially for forensic applications. The Laotian sequences will be incorporated into the collaborative EMPOP mtDNA database <url>http://www.empop.org</url> upon publication and will be available as the first mtDNA reference data for this country.</p
SINTESIS MAGNETIT (Fe3O4) NANOPARTIKEL DENGAN NATRIUM DODESIL SULFAT
Telah dilakukan sintesis magnetit (Fe3O4) nanopartikel dengan Natrium Dodesil Sulfat (NaDS). Penelitian ini bertujuan untuk mengetahui pengaruh NaDS terhadap karakter kimia dan fisik magnetit nanopartikel hasil sintesis dengan metode kopresipitasi. Sintesis magnetit nanopartikel dilakukan dengan mereaksikan FeSO4.7H2O dan FeCl3.6H2O dengan perbandingan mol 1:2 serta natrium hidroksida (NaOH) sebagai presipitan dengan proses pengadukan pada suhu 60 °C selama 2 jam. Kajian pengaruh surfaktan pada sintesis magnetit nanopartikel dilakukan dengan variasi konsentrasi NaDS dari 1%, 3% dan 6% (b/v). Material hasil sintesis dikarakterisasi dengan spektrofotometer X-ray diffraction (XRD), Fourier Transform Infrared Spectrometer (FTIR), Scanning Electron Microscope-Energy Dispersive X-ray (SEM-EDX) dan Surface Area Analyzer (SAA). Hasil penelitian menunjukkan bahwa magnetit nanopartikel berhasil disintesis. Magnetit ditunjukkan oleh puncak difraksi utama pada 2θ 30,43o; 35,53o; 43,46o; 57,32o dan 62,84o. Ikatan Fe–O ditunjukkan dengan puncak serapan 565 cm-1 yang dianalisa lebih lanjut menggunakan EDX menunjukkan adanya unsur Fe dan O. Adanya surfaktan NaDS menaikkan ukuran partikel dan ukuran kristal magnetit dengan meningkatnya konsentrasi NaDS yang ditambahkan. Morfologi magnetit-NaDS semakin homogen berbentuk butiran-butiran kecil (grain) dengan ukuran partikel sekitar 30-100 nm. Ukuran kristal magnetit sebesar 11,07 nm (magnetit tanpa surfaktan); 13,62 nm (magnetit-NaDS 1%); 16,12 nm (magnetit-NaDS 3%) dan 11,17 nm (magnetit-NaDS 6%). Luas permukaan magnetit nanopartikel berturut-turut sebesar 89,67 m2/g (magnetit tanpa surfaktan); 102,50 m2/g (magnetit-NaDS 1%); 98,45 m2/g (magnetit-NaDS 3%) dan 82,92 m2/g (magnetit-NaDS 6%)
Comparison of the environmental assessment of an identical office building with national methods
The IEA EBC Annex 72 focuses on the assessment of the primary energy demand, greenhouse gas emissions and environmental impacts of buildings during production, construction, use (including repair and replacement) and end of life (dismantling), i.e. during the entire life cycle of buildings. In one of its activities, reference buildings (size, materialisation, operational energy demand, etc.) were defined on which the existing national assessment methods are applied using national (if available) databases and (national/regional) approaches. The ?be2226? office building in Lustenau, Austria was selected as one of the reference buildings. TU Graz established a BIM model and quantified the amount of building elements as well as construction materials required and the operational energy demand. The building assessment was carried out using the same material and energy demand but applying the LCA approach used in the different countries represented by the participating Annex experts. The results of these assessments are compared in view of identifying major discrepancies. Preliminary findings show that the greenhouse gas emissions per kg of building material differ up to a factor of two and more. Major differences in the building assessments are observed in the transports to the construction site (imports) and the construction activities as well as in the greenhouse gas emissions of the operational energy demand (electricity). The experts document their practical difficulties and how they overcame them. The results of this activity are used to better target harmonisation efforts.IEA -International Association for the Evaluation of Educational Achievement(Slovenia
Outlining a new collaborative business model as a result of the green Building Information Modelling impact in the AEC supply chain
BIM (Building Information Modelling) technological push has enabled to integrate the design/construction outcomes of 3D-CAD along the product/service AEC (Architecture, Engineering and Construction) SC (supply chain) through an intelligent DMS (Data Management System) based on standard and interoperable data formats. The proposed end-to-end approach overcomes a typical AEC gap, enables the operationalisation of the sustainable/green building LCA (Life Cycle Assessment) and puts together new collaborative relationships with the owner, among SC stakeholders and with new forms of BIM procurement. The outlined collaborative business model is based on the Quality Control and Assurance framework and provides conceptual consistency to the reintroduction of the owner concerns/satisfaction in the SC, as well as enables consistent and accountable relationships between (smart)materials procurement and building specification. An expert’s focus group carried out a preliminary check of the model’s interest/applicability, resulting in recommendations for its further detailing and for propositions development into a systematic enquiring process.info:eu-repo/semantics/acceptedVersio
Analysis of Male Pheromones That Accelerate Female Reproductive Organ Development
Male odors can influence a female's reproductive physiology. In the mouse, the odor of male urine results in an early onset of female puberty. Several volatile and protein pheromones have previously been reported to each account for this bioactivity. Here we bioassay inbred BALB/cJ females to study pheromone-accelerated uterine growth, a developmental hallmark of puberty. We evaluate the response of wild-type and mutant mice lacking a specialized sensory transduction channel, TrpC2, and find TrpC2 function to be necessary for pheromone-mediated uterine growth. We analyze the relative effectiveness of pheromones previously identified to accelerate puberty through direct bioassay and find none to significantly accelerate uterine growth in BALB/cJ females. Complementary to this analysis, we have devised a strategy of partial purification of the uterine growth bioactivity from male urine and applied it to purify bioactivity from three different laboratory strains. The biochemical characteristics of the active fraction of all three strains are inconsistent with that of previously known pheromones. When directly analyzed, we are unable to detect previously known pheromones in urine fractions that generate uterine growth. Our analysis indicates that pheromones emitted by males to advance female puberty remain to be identified
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