16,104 research outputs found
Coordinated NanoSIMS and TEM Analysis of a Large 26Mg-Rich AGB Silicate from the Meteorite Hills 00426 CR2 Chondrite
Silicates are one of the most abundant presolar phases around evolved stars, in the inter-stellar medium (ISM), and in our Solar System. These grains afford the opportunity for O, Si, Mg, Fe, and Ca isotopic analyses to constrain stellar nucleosynthetic and mixing processes, and Galactic chemical evolution (GCE). While Mg and Fe isotopic studies have been successfully conducted on presolar silicates, isotopic analyses beyond O and Si are often hampered by the small grain sizes (average ~250 nm). This also makes coordinated mineral and chemical characterization challenging. These studies provide insight into the dust condensation conditions as well as subsequent alteration in the ISM and/or the Solar System. TEM studies of presolar silicates have shown that they are much more mineralogically and chemically diverse than other presolar phases [1 and references therein]. Large (>500nm) presolar silicate grains are rare, but they allow for detailed isotopic, mineral, and chemical characterization. We identified a large presolar silicate grain in the MET 00426 CR2 chondrite and report the O, Si, Mg, and Fe isotopic compositions and TEM study of this grain
The Urgency of Representatives Establishment of Witnesess and Victims Protection Agency (Lpsk) in Local Areas
Granting protection of witnesses and/or victims by LPSK that standing only in the capital of the Republic of Indonesia, Jakarta, there are problems to be debate among legal practitioners. The problem comes when a large number of requests that come to the LPSK is derived from various regions across Indonesia in the motherland, which often witnesses and/or victims who came from across the region who are far enough away will certainly require a large fee to head to Jakarta so that witnesses and/or victims are having trouble accessing request protection to LPSK. LPSK itself set in Article 11 of Law On Witnesses and Victims Protection. Representatives establishment office in fact already regulated on Article 11 paragraph (3), but in practice despite the fact a lot of the problems that come from the region, LPSK up to this moment does not form a representative in the local area
Adjusting the frequency of mammography screening on the basis of genetic risk: Attitudes among women in the UK.
Purpose
To explore public attitudes towards modifying frequency of mammography screening based on genetic risk.
Methods
Home-based interviews were carried out with a population-based sample of 942 women aged 18ā74 years in the UK. Demographic characteristics and perceived breast cancer (BC) risk were examined as predictors of support for risk-stratified BC screening and of the acceptability of raised or lowered screening frequency based on genetic risk, using multivariate logistic regression.
Results
Over two-thirds of respondents (65.8%) supported the idea of varying screening frequency on the basis of genetic risk. The majority (85.4%) were willing to have more frequent breast screening if they were found to be at higher risk, but fewer (58.8%) were willing to have less frequent screening if at lower risk (t (956) = 15.6, p < 0.001). Ethnic minority status was associated with less acceptability of more frequent screening (OR = 0.40, 95% CI = 0.21ā0.74), but there were no other significant demographic correlates. Higher perceived risk of BC was associated with greater acceptability of more frequent screening (OR = 1.71, 95%CI = 1.27ā2.30).
Conclusion
Women were positive about adjusting the frequency of mammography screening in line with personal genetic risk, but it will be important to develop effective communication materials to minimise resistance to reducing screening frequency for those at lower genetic risk
Arginine mutation alters binding of a human monoclonal antibody to antigens linked to systemic lupus erythematosus and the antiphospholipid syndrome
Objective: Previous studies have shown the importance of somatic mutations and arginine residues in the complementarity-determining regions (CDRs) of pathogenic anti-double-stranded DNA (anti-dsDNA) antibodies in human and murine lupus, and in studies of murine antibodies, a role of mutations at position 53 in VH CDR2 has been demonstrated. We previously demonstrated in vitro expression and mutagenesis of the human IgG1 monoclonal antibody B3. The present study was undertaken to investigate, using this expression system, the importance of the arginine residue at position 53 (R53) in B3 VH.
Methods: R53 was altered, by site-directed mutagenesis, to serine, asparagine, or lysine, to create 3 expressed variants of VH. In addition, the germline sequence of the VH3-23 gene (from which B3 VH is derived) was expressed either with or without arginine at position 53. These 5 new heavy chains, as well as wild-type B3 VH, were expressed with 4 different light chains, and the resulting antibodies were assessed for their ability to bind to nucleosomes, -actinin, cardiolipin, ovalbumin, 2-glycoprotein I (2GPI), and the N-terminal domain of 2GPI (domain I), using direct binding assays.
Results: The presence of R53 was essential but not sufficient for binding to dsDNA and nucleosomes. Conversely, the presence of R53 reduced binding to -actinin, ovalbumin, 2GPI, and domain I of 2GPI. The combination B3 (R53S) VH/B3 VL bound human, but not bovine, 2GPI.
Conclusion: The fact that the R53S substitution significantly alters binding of B3 to different clinically relevant antigens, but that the alteration is in opposite directions depending on the antigen, implies that this arginine residue plays a critical role in the affinity maturation of antibody B3
Gathering experience in trust-based interactions
As advances in mobile and embedded technologies coupled with progress in adhoc networking fuel the shift towards ubiquitous computing systems it is becoming increasingly clear that security is a major concern. While this is true of all computing paradigms, the characteristics of ubiquitous systems amplify this concern by promoting spontaneous interaction between diverse heterogeneous entities across administrative boundaries [5]. Entities cannot therefore rely on a specific control authority and will have no global view of the state of the system. To facilitate collaboration with unfamiliar counterparts therefore requires that an entity takes a proactive approach to self-protection. We conjecture that trust management is the best way to provide support for such self-protection measures
Valley filtering and spatial maps of coupling between silicon donors and quantum dots
Exchange coupling is a key ingredient for spin-based quantum technologies
since it can be used to entangle spin qubits and create logical spin qubits.
However, the influence of the electronic valley degree of freedom in silicon on
exchange interactions is presently the subject of important open questions.
Here we investigate the influence of valleys on exchange in a coupled
donor/quantum dot system, a basic building block of recently proposed schemes
for robust quantum information processing. Using a scanning tunneling
microscope tip to position the quantum dot with sub-nm precision, we find a
near monotonic exchange characteristic where lattice-aperiodic modulations
associated with valley degrees of freedom comprise less than 2~\% of exchange.
From this we conclude that intravalley tunneling processes that preserve the
donor's and valley index are filtered out of the interaction
with the valley quantum dot, and that the and
intervalley processes where the electron valley index changes are weak.
Complemented by tight-binding calculations of exchange versus donor depth, the
demonstrated electrostatic tunability of donor/QD exchange can be used to
compensate the remaining intravalley oscillations to realise uniform
interactions in an array of highly coherent donor spins.Comment: 6 pages, 4 figures, 6 pages Supplemental Materia
Berudu Anura di Sungai Kedurang, Bengkulu Selatan dan Pusat Pendidikan Konservasi Alam Bodogol, Jawa Barat
This paper aims is to identify and to describe morphological characteristic of tadpoles in Kedurang River, South Bengkulu and Cisuren River, PPKA Bodogol. Visual Encounter Survey along the river method was used to collect the sample of tadpoles. Three species were found in both rivers, namely Bufo melanostictus, Limnonectes sp. and Rhacophorus sp
Desain Sistem Keamanan Pangan Hazard Analysis and Critical Control Point (Haccp) Pada Proses Produksi Gula Pg. Kebon Agung Malang
PG Kebon Agung merupakan salah satu Perusahaan yang memproduksi Gula yang berlokasi di Kabupaten Malang. Jenis gula yang dihasilkan adalah gula kristal putih. PG Kebon Agung belum menerapkan sistem keamanan pangan pada lantai produksinya, padahal pada tahapan proses produksinya banyak menggunakan bahan-bahan kimia berbahaya yang sangat tidak baik apabila terkomsumsi oleh konsumen. Untuk itu dilakukan perencanaan desain sitem keamanan pangan, Hazard Analysis and Critical Control Point (HACCP), yang bertujuan untuk mengidentifikasi bahaya-bahaya yang cenderung terjadi pada lantai produksi dan menempatkan pengendalian yang diharapkan dapat mencegah, mengurangi, bahkan menghilangkan bahaya-bahaya tersebut. Hasil analisa dengan menggunakan prinsip-prinsip yang ada pada metode HACCP didapat 9 titik kendali kritis atau critical control point (CCP) yang ada pada proses produksi gula kristal putih. kesembilan CCP tersebut, lebih rinci lagi, terdapat pada proses pencucian (kontaminasi fisik), proses pemberian desinfektan (kontaminasi biologi dan kimia), proses penambahan asam phospat (kontaminasi kimia), proses penambahan susu kapur (kontaminasi fisik), proses pelepasa gas-gas sisa rekasi (kontaminasi kimia), proses penambahan flocculant (kontaminasi fisik dan kimia), dan proses pemberian fondan (kontaminasi kimia). Tabel HACCP Plan sebagai hasil atau output dari sistem HACCP telah mencakup keseluruhan hasil analisa dari prinsip-prinsip HACCP
The Role of Solar Wind Hydrogen in Space Weathering: Insights from Laboratory-Irradiated Northwest Africa 12008
Micrometeoroid impacts, solar wind plasma interactions, and regolith gardening drive the complicated and nuanced mechanism of space weathering (or optical maturation); a process by which a materials optical properties are changed as a result of chemical and physical alterations at the surface of grains on airless bodies. Reddened slopes, attenuated absorption bands, and an overall reduction in albedo in the visible and near-IR wavelength ranges are primarily the result of native iron nanoparticle (npFe0) production within glassy rims that form from sputtering and vaporization. The sizes and abundance of these particles provide information about the relative surface exposure age of a particular grain. In addition, many studies have indicated that composition greatly affects the rate at which optical maturation occurs. Despite our understanding of how npFe0 affects optical signatures, the relative roles of micrometeoroid bombardment and solar wind interactions remains undetermined. To simulate the early effects of weathering by the solar wind and to determine thresholds for optical change with respect to a given mineral phase, we irradiated a fine-grained lunar basalt with 1 keV H+ to a fluence of 6.4 x 1016 H+ per sq.cm. Surface alterations within four phases have been evaluated using transmission electron microscopy (TEM). We found that for a given fluence of H+, the extent of damage acquired by each grain was dependent on its composition. No npFe(0) was produced in any of the phases evaluated in this study. These results are consistent with many previous studies conducted using ions of similar energy, but they also provide valuable information about the onset of space weathering and the role of the solar wind during the early stages of optical maturation
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