18 research outputs found
CHAPTER 1. Risk Assessment of Plastic-based Food Contact Materials: Focus on Polyolefins
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No full textt is common knowledge that over the last decade there has been a major boost in communication networks. In fact, the development of high-performance backbone networks was immediately followed by the rapid dissemination of broadband wired access technologies, such as leased lines based on fiber-optic links, cable modems using coaxial systems, and digital subscriber line (xDSL) access networks. This gave users a whole new class of services that exploit the increasing number of available network resources. Many new services are based on multimedia applications, such as voice over IP (VoIP), video conferencing, video on demand (VoD), massive online gaming, and peer-to-peer. Unlike traditional TCP/IP services, multimedia applications usually require strict network guarantees such as reserved bandwidth or bounded delays. The broadband access phenomenon has been investigated by the International Telecommunication Union (ITU), which reported in [1] that Broadband Wireless Access (BWA), although still in the early stage of its growth, is one of the most promising solutions for broadband access. Standards for BWA are being developed within IEEE Project 802, working group 16, also referred to as 802.16 The challenge for BWA networks is in providing quality of service (QoS) simultaneously to services with very different characteristics. QoS support in wireless networks is a much more difficult task than in wired networks, mainly because the characteristics of a wireless link are highly variable and unpredictable, both on a time-dependent basis and a locationdependent basis. To cope with such issues, QoS in wireless networks is usually managed at the medium access control (MAC) layer. Despite the fact that the launch of 802.16 products has already been announced on the market by several manufacturers, the research literature still lacks a sufficient number of studies that specifically address the analysis of the 802.16 MAC protocol. In [4] the author performed a hybrid analytical-simulative analysis of the effect on the system performance of several MAC mechanisms, including the fragmentation of service data units (SDUs) and the padding of OFDM symbols. The performance with the time-division duplex (TDD) mode was partially analyzed in In this article, we review and analyze the mechanisms for supporting QoS at the IEEE 802.16 MAC layer. We then analyze by simulation the performance of IEEE 802.16 in two application scenarios, which consist of providing last-mile Internet access for residential and SME subscribers, respectively. Our analysis is aimed at showing the effectiveness of the 802.16 MAC protocol in providing differentiated services to applications with different QoS requirements, such as VoIP and Web. Abstract During the last few years, users all over the world have become more and more accustomed to the availability of broadband access. This has boosted the use of a wide variety both of established and recent multimedia applications. However, there are cases where it is too expensive for network providers to serve a community of users. This is typically the case in rural and suburban areas, where there is slow deployment (or no deployment at all) of traditional wired technologies for broadband access (e.g., cable modems, xDSL). In those cases, the most promising opportunity rests with Broadband Wireless Access technologies, such as the IEEE 802.16, also known as WiMAX. One of the features of the MAC layer of 802.16 is that it is designed to differentiate service among traffic categories with different multimedia requirements. This article focuses on mechanisms that are available in an 802.16 system to support quality of service (QoS) and whose effectiveness is evaluated through simulation. Quality of Servic
Programmed Field Decay Thermal Field Flow Fractionation of Polymers: A Calibration Method
No full textThe universal calibration procedure typical of thermal field
flow fractionation (ThFFF) under constant thermal field
operation was extended to thermal field programming
(TFP) operation. The method requires knowledge of the
following: (a) the programming function, which only
depends on the thermal field decay function, (b) the
physicochemical properties of the solvent, and (c) the
calibration plot under varying channel cold wall temperatures (Tc). Two field flow fractionation field programming
conditions, with either a constant or a variable in time
carrier flow velocity, are exploited. The method is based
on determination, for each retention time position, of the
average λ retention value typical of TFP ThFFF. This
parameter is then used to obtain the calibration plot (i.e.,
the molecular weight of the species as a function of the
retention time position) by using the programming function and the calibration plot under varying Tc values. The
procedure approximation errors are also derived as a
function of the programming type and solute−solvent
system. To properly test the procedure, the calibration
plot for the system constituted by polystyrene (PS) in cis−trans Decalin was determined, under varying conditions
Tc and thermal gradients, by using a set of monodisperse
PS standards of different molecular weights (M). The
procedure was first validated by simulation under two
typical cases of TFP ThFFF operation. The approximation
errors were found acceptable (in the worse cases, the
accuracy in M prediction was 3%) and are in agreement
with the theory. The procedure was then experimentally
validated under varying programming decay function
conditions. The reproducibility and accuracy of the M
determination are both better than 2%
Author Correction: μMAPPS: a novel phasor approach to second harmonic analysis for in vitro-in vivo investigation of collagen microstructure
No full textA correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.</jats:p
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Author Correction: μMAPPS: a novel phasor approach to second harmonic analysis for in vitro-in vivo investigation of collagen microstructure
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Author Correction: Detection of urinary podocytes by flow cytometry in idiopathic membranous nephropathy (Scientific Reports, (2020), 10, 1, (16362), 10.1038/s41598-020-73335-2)
No full textJWST MIRI Detections of Hα and [O III] and a Direct Metallicity Measurement of the z = 10.17 Lensed Galaxy MACS0647‑JD
No full textHsiao, Tiger Yu-Yang et al.-- Full list of authors: Hsiao, Tiger Yu-Yang; Álvarez-Márquez, Javier; Coe, Dan; Crespo Gómez, Alejandro; Abdurro'uf; Dayal, Pratika; Larson, Rebecca L.; Bik, Arjan; Blanco-Prieto, Carmen; Colina, Luis; Pérez-González, Pablo Guillermo; Costantin, Luca; Prieto-Jiménez, Carlota; Adamo, Angela; Bradley, Larry D.; Conselice, Christopher J.; Fujimoto, Seiji; Furtak, Lukas J.; Hutchison, Taylor A.; James, Bethan L.; Jiménez-Teja, Yolanda; Jung, Intae; Kokorev, Vasily; Mingozzi, Matilde; Norman, Colin; Ricotti, Massimo; Rigby, Jane R.; Sharon, Keren; Vanzella, Eros; Welch, Brian; Xu, Xinfeng; Zackrisson, Erik; Zitrin, AdiJWST spectroscopy has revolutionized our understanding of galaxies in the early Universe. Covering wavelengths up to 5.3 μm, NIRSpec can detect rest-frame optical Hα emission lines out to z = 7 and [O III] to z = 9.5. Observing these lines in more distant galaxies requires longer wavelength spectroscopy with MIRI. Here we present MIRI Medium Resolution Spectrograph integral field unit observations of the lensed galaxy merger MACS0647–JD at z = 10.165. With exposure times of 4.2 hr in each of two bands (SHORT and LONG), we detect Hα at 9σ, [O III] λ5008 at 11σ, and [O III] λ4960 at 3σ. Combined with previously reported NIRSpec spectroscopy that yielded seven emission lines including the auroral line [O III] λ4363, we present the first direct metallicity measurement of a z > 10 galaxy: 12+log(O/H)=7.79±0.09 , or 0.13‑0.03+0.02Z⊙ . This is similar to galaxies at z ∼ 4–9 with direct metallicity measurements, though higher than expected given the high specific star formation rate log(sSFR/yr‑1) = ‑7.4 ± 0.3. We further constrain the ionization parameter log(U) = ‑1.9 ± 0.1, ionizing photon production efficiency log(ξ ion) = 25.3 ± 0.1, and SFR = 5.0 ± 0.6 M ⊙ yr‑1 within the past 10 Myr. These observations demonstrate the combined power of JWST NIRSpec and MIRI for studying galaxies in the first 500 million years. © 2024. The Author(s).This work is based on observations made with the NASA/ESA/CSA James Webb Space Telescope (JWST) and Hubble Space Telescope (HST). The data were obtained from the Mikulski Archive for Space Telescopes (MAST) at the Space Telescope Science Institute (STScI), which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under NASA contract NAS 5-03127 for JWST. We are grateful and indebted to the 20,000 people who worked to make JWST an incredible discovery machine. These observations are associated with JWST programs GO 4246 and 1433, and HST GO 9722, 10493, 10793, and 12101. T.H. is funded by a grant for JWST-GO-01433 and JWST-GO-04212 provided by STScI under NASA contract NAS 5-03127. T.H. appreciates the support from the Government scholarship to study abroad (Taiwan). A. is funded by a grant for JWST-GO-01433 and JWST-GO-04246 provided by STScI under NASA contract NAS 5-03127. A.A. acknowledges support by the Swedish research council Vetenskapsrådet (2021-05559). A.B. acknowledges support from the Swedish National Space Administration (SNSA). E.Z. acknowledges project grant 2022-03804 from the Swedish Research Council (Vetenskapsrådet) and has also benefited from a sabbatical at the Swedish Collegium for Advanced Study. A.Z. and L.J.F. acknowledge support by grant No. 2020750 from the United States-Israel Binational Science Foundation (BSF), grant No. 2109066 from the United States National Science Foundation (NSF), and by the Ministry of Science & Technology, Israel. J.A.-M., L.C., A.C.-G., and C.P.-J. acknowledge support by grant PIB2021-127718NB-100 from the Spanish Ministry of Science and Innovation/State Agency of Research MCIN/AEI/10.13039/501100011033 and by "ERDF A way of making Europe." C.B.-P. acknowledges support by grant CM21_CAB_M2_01 from the Program "Garantía Juveníl" from the "Comunidad de Madrid" 2021. P.D. acknowledge support from the NWO grant 016.VIDI.189.162 ("ODIN") and warmly thanks the European Commission's and University of Groningen's CO-FUND Rosalind Franklin program. A.Z. acknowledges support by grant No. 2020750 from the United States-Israel Binational Science Foundation (BSF) and grant No. 2109066 from the United States National Science Foundation (NSF), by the Ministry of Science & Technology, Israel, and by the Israel Science Foundation grant No. 864/23.Peer reviewe
The role of the coactivators PGC-1α and PGC-1β in retina and skeletal muscle
No full textPeroxisome proliferator-activated receptor γ coactivator- 1 (PGC-1) designates a family of coactivators consisting of PGC-1α, PGC-1β and PRC. By associating with transcription factors like nuclear receptors, they induce transcription of target genes that are responsible for mitochondrial biogenesis, glucose uptake, gluconeogenesis, oxidative phosphorylation and β-oxidation of fatty acids. Originally identified in brown adipose tissue, these coactivators are predominately expressed in tissues with high energy requirements (skeletal muscle, heart, liver, brain, kidney) upon stimulation with physiological stressors (exercise, cold, fasting). PGC-1’s expression and function is therefore highly tissue specific. PGC-1α is to date the best studied of all family members.
One of the tissues high in energy demand is the retina; its photoreceptors convert light into a signal that can be interpreted by the brain. However, thus far the physiological role of PGC-1α has never been studied there. In the first project of this thesis, we consequently analyzed PGC-1α and to a certain extent also PGC-1β expression and function in mouse retina: We first assessed expression patterns of PGC-1α and PGC-1β. Second, we subjected mice with a global deletion of the PGC-1α gene (PGC-1α knockout = KO) and wildtype (WT) control mice to high intensity light compared to a dark setting and studied their retinae’s morphology (histology), function (electroretinogram) and gene expression levels (microarray, real time PCR). We found the PGC-1α KO mice to display increased apoptosis and disrupted retinal photoreceptor structure compared to the wildtype (WT) control animals upon light exposure. The corresponding light damage could also be confirmed by ERG in some animals. Microarray analysis revealed downregulation of DNA repair and phototransduction as well as an upregulation of inflammatory and apoptotic pathways, respectively in the KO animals. Finally, we confirmed in an in vitro setting that overexpression of PGC-1α helped alleviate apoptosis.
The role of PGC-1β in skeletal muscle has not been thoroughly studied either: More specifically, we wanted to address its role in glucose metabolism/ insulin sensitivity and fiber type composition as well as to identify exclusive target genes of PGC-1β in this tissue in the second project. For this purpose, we aimed at generating a skeletal muscle specific knockdown mouse: Different small hairpin RNAs (shRNAs) and control, scrambled shRNAs against mouse PGC-1β were designed according to different design principles (shRNA vs shRNA-mir) and tested for their knockdown efficiency and specificity in cell culture. The most promising one was then inserted into a vector backbone used to generate adeno-associated virus (AAV). We decided to produce the AAV serotype AAV2/6, as it displays specific tropism for skeletal muscle (AAV2/6). Injection quantity, route and duration until onset of shRNA expression were optimized with a virus expressing green fluorescent protein (GFP). The virus carrying shRNA was then injected into the mouse tibialis anterior muscle and after 3 weeks of incubation time analyzed for inflammatory gene expression. Semi- quantitative real time PCR analysis revealed that expression of PGC-1β as well as of its downstream target genes was significantly reduced. In vivo testing of a skeletal muscle specific promoter, however, did not lead to a significant reduction of PGC-1β levels.
In summary, we showed that PGC-1α has a protective role in light induced apoptosis in the retina (project1).
In project 2, we showed that a reduction of PGC-1β in skeletal muscle leads to diminished expression of genes implicated in OXPHOS
