1,189 research outputs found
Molecular Lines as Diagnostics of High Redshift Objects
Models are presented for CO rotational line emission by high redshift
starburst galaxies. The influence of the cosmic microwave background on the
thermal balance and the level populations of atomic and molecular species is
explicitly included. Predictions are made for the observability of starburst
galaxies through line and continuum emission between z=5 and z=30. It is found
that the Millimeter Array could detect a starburst galaxy with ~10^5 Orion
regions, corresponding to a star formation rate of about 30 Mo yr^{-1}, equally
well at z=5 or z=30 due to the increasing cosmic microwave background
temperature with redshift. Line emission is a potentially more powerful probe
than dust continuum emission of very high redshift objects.Comment: 15 pages LaTex, uses aasms4.sty, Accepted by ApJ
Parched elastohydrodynamic lubrication: Instrumentation and procedure
A counter rotating bearing rig was designed and constructed to study transient elastohydrodynamic lubrication phenomena. New instrumentation is described and test procedures are documented. Ball and race speed measurement systems and the capacitance (film thickness) measurement system were upgraded. Methods for measuring bearing torque and race temperatures were implemented
Lubricated Bearing Lifetimes of a Multiply Alkylated Cyclopentane and a Linear Perfluoropolyether Fluid in Oscillatory Motion at Elevated Temperatures in Ultrahigh Vacuum
Bearing life tests in vacuum with three space liquid lubricants, two multiply alkylated cyclopentanes (MACs) and a linear perfluoropolyether (PFPE) were performed. Test conditions included: an 89 N axial load (mean Hertzian stress 0.66 GPa), vacuum level below 7x10(exp -4) Pa, and a +/-30deg dither angle. Dither rate was 75 cycles per minute. Higher (110 to 122 C) and lower temperature tests (75 C) were performed. For the higher temperature tests, the PFPE, Fomblin (Ausimont SpA) Z25 outperformed Pennzane (Shell Global Solutions) X-2000 by more than an order of magnitude. Lubricant evaporation played a key role in these high temperature results. At 75 C, the order was reversed with both Pennzane X-1000 and X-2000 outperforming Fomblin Z25 by more than an order of magnitude. Most Pennzane tests were suspended without failure. The primary failure mechanism in these lower temperature tests was lubricant consumption in the tribocontacts
Aplikasi Pembayaran Iuran Sekolah Katolik Yayasan Sagrado CoraĆ§Ć£o de Jesus Berbasis Web
The Sagrado CoraĆ§Ć£o de Jesus Foundation is a formal educational institution that manages 58 Catholic schools in the Maliana Diocese of Timor Leste. In dealing with the payment of fees, Catholic schools under the Sagrado CoraĆ§Ć£o de Jesus Foundation still use books to record payment transactions. These transactions must be carried out at the foundation, and it takes a long time to record transactions in the book so that it becomes a problem faced by the foundation, schools, and parents of students. A web-based school tuition payment application is needed by the Sagrado CoraĆ§Ć£o de Jesus Foundation to handle the school's tuition payment activities on behalf. The use of website media makes it easier for parents to show proof of payment without having to come to the foundation. Applications that are built can also speed up the process of recording the payment of contributions by foundation employees. Based on the research results, the Web-based application for payment of tuition fees for Catholic schools at the Sagrado CoraĆ§Ć£o de Jesus Foundation makes it easier for parents and foundations to make payment transactions more efficiently and quickly.Yayasan Sagrado CoraĆ§Ć£o de Jesus adalah sebuah lembaga pendidikan formal yang mengelola 58 sekolah Katolik di wilayah Keuskupan Maliana Timor Leste. Dalam menangani kegiatan pembayaran iuran, sekolah-sekolah Katolik yang bernaung di bawah Yayasan Sagrado CoraĆ§Ć£o de Jesus masih menggunakan buku untuk mencatat transaksi pembayaran. Transaksi tersebut wajib dilakukan di Yayasan serta dibutuhkan waktu yang lama untuk mencatat transaksi di buku sehingga menjadi masalah yang dihadapi oleh pihak yayasan, sekolah, maupun orang tua siswa. Sebuah aplikasi pembayaran iuran sekolah berbasis web dibutuhkan oleh Yayasan Sagrado CoraĆ§Ć£o de Jesus untuk menangani kegiatan pembayaran iuran sekolah-sekolah milik yayasan. Penggunaan media website memudahkan orang tua untuk menunjukkan bukti pembayaran tanpa harus datang ke yayasan. Aplikasi yang dibangun juga dapat mempercepat proses pencatatan pembayaran iuran oleh pegawai yayasan. Berdasarkan hasil penelitian, aplikasi pembayaran iuran sekolah-sekolah Katolik di Yayasan Sagrado CoraĆ§Ć£o de Jesus Berbasis Web memudahkan orang tua serta yayasan dalam melakukan transaksi pembayaran yang lebih efisien dan cepat
The balance between NAD+ biosynthesis and consumption in ageing
Nicotinamide adenine dinucleotide (NAD+) is a vital coenzyme in redox reactions. NAD+ is also important in cellular signalling as it is consumed by PARPs, SARM1, sirtuins and CD38. Cellular NAD+ levels regulate several essential processes including DNA repair, immune cell function, senescence, and chromatin remodelling. Maintenance of these cellular processes is important for healthy ageing and lifespan. Interestingly, the levels of NAD+ decline during ageing in several organisms, including humans. Declining NAD+ levels have been linked to several age-related diseases including various metabolic diseases and cognitive decline. Decreasing tissue NAD+ concentrations have been ascribed to an imbalance between biosynthesis and consumption of the dinucleotide, resulting from, for instance, reduced levels of the rate limiting enzyme NAMPT along with an increased activation state of the NAD+-consuming enzymes PARPs and CD38. The progression of some age-related diseases can be halted or reversed by therapeutic augmentation of NAD+ levels. NAD+ metabolism has therefore emerged as a potential target to ameliorate age-related diseases. The present review explores how ageing affects NAD+ metabolism and current approaches to reverse the age-dependent decline of NAD+.publishedVersio
Risk as affect:the affect heuristic in cybersecurity
Risk perception is an important driver of netizensā (Internet usersā) cybersecurity behaviours, with a number of factors influencing its formation. It has been argued that the affect heuristic can be a source of variation in generic risk perception. However, a major shortcoming of the supporting research evidence for this assertion is that the central construct, affect, has not been measured or analysed. Moreover, its influence in the cybersecurity domain has not yet been tested. The contribution of the research reported in this paper is thus, firstly, to test the affect heuristic while measuring its three constructs: affect, perceived risk and perceived benefit and, secondly, to test its impact in the cybersecurity domain. By means of two carefully designed studies (NāÆ=āÆ63 and NāÆ=āÆ233), we provide evidence for the influence of the affect heuristic on risk perception in the cybersecurity domain. We conclude by identifying directions for future research into the role of affect and its impact on cybersecurity risk perception
Sources of inversion variation in the small single copy (SSC) region of chloroplast genomes
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141571/1/ajb21751.pd
Xylem surfactants introduce a new element to the cohesion-tension theory
Vascular plants transport water under negative pressure without constantly creating gas bubbles that would disable their hydraulic systems. Attempts to replicate this feat in artificial systems almost invariably result in bubble formation, except under highly controlled conditions with pure water and only hydrophilic surfaces present. In theory, conditions in the xylem should favor bubble nucleation even more: there are millions of conduits with at least some hydrophobic surfaces, and xylem sap is saturated or sometimes supersaturated with atmospheric gas and may contain surface-active molecules that can lower surface tension. So how do plants transport water under negative pressure? Here, we show that angiosperm xylem contains abundant hydrophobic surfaces as well as insoluble lipid surfactants, including phospholipids, and proteins, a composition similar to pulmonary surfactants. Lipid surfactants were found in xylem sap and as nanoparticles under transmission electron microscopy in pores of intervessel pit membranes and deposited on vessel wall surfaces. Nanoparticles observed in xylem sap via nanoparticle-tracking analysis included surfactant-coated nanobubbles when examined by freeze-fracture electron microscopy. Based on their fracture behavior, this technique is able to distinguish between dense-core particles, liquid-filled, bilayer-coated vesicles/liposomes, and gas-filled bubbles. Xylem surfactants showed strong surface activity that reduces surface tension to low values when concentrated as they are in pit membrane pores. We hypothesize that xylem surfactants support water transport under negative pressure as explained by the cohesion-tension theory by coating hydrophobic surfaces and nanobubbles, thereby keeping the latter below the critical size at which bubbles would expand to form embolisms
Risk perceptions of cyber-security and precautionary behaviour
A quantitative empirical online study examined a set of 16 security hazards on the Internet and two comparisons in 436 UK and US students, measuring perceptions of risk and other risk dimensions. First, perceived risk was highest for identity theft, keylogger, cyber-bullying and social engineering. Second, consistent with existing theory, significant predictors of perceived risk were voluntariness, immediacy, catastrophic potential, dread, severity of consequences and control, as well as Internet experience and frequency of Internet use. Moreover, control was a significant predictor of precautionary behaviour. Methodological implications emphasise the need for non-aggregated analysis and practical implications emphasise risk communication to Internet users
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