55,419 research outputs found
NbN-MgO-NbN tunnel junctions integrated in aluminum strip lines for terahertz quasiparticle mixers
No full textNbN tunnel junctions are of great interest for THz heterodyne receivers because their large gap voltage of V-gap approximate to 5 mV implies an upper frequency limit of 4 Delta/h approximate to 2.6 THz as compared to 1.4 THz of Nb. However, due to the high ac losses in NbN films for frequencies above the NbN gap frequency, 2 Delta/h approximate to 1.3 THz, NbN matching circuits cannot be used. Lower losses are achieved with normal metals such as Al. Both for waveguide mixers and quasioptical mixers, quartz substrates are preferred. We report on a room-temperature fabrication process for NbN-MgO-NbN junctions with surfaces below 1 mu m(2) integrated in Al strip lines on quartz substrates. Appropriate plasma conditions for NbN-film deposition are obtained through the use of a second Nb target which acts as a selective nitrogen pump. NbN films on quartz substrates with and without an intermediate layer of Al have T-c > 15 K and rho(N) = 100 - 130 mu Omega.cm. Nb buffers should prevent the possible formation of insulating AIN at the Al-NbN interfaces. We fabricated the first NbN junctions sandwiched between Al layers. Sputtered Al were employed. Critical-current densities of up to 60 kA/cm(2) and subgap resistances R-sg approximate to 5.R-N were achieved. The I-V curves show various structures below the gap voltage. We discuss here the observation of a distinct steep step at eV = 2 Delta/3
Contribution of different rumen micorbial groups to production of gas, shot chain fatty acids and ammonium from different diets in an in vitro fermentation system
No full text"Why Were Poverty Rates So High in the 1980s?"
No full textThis paper explores the unexpectedly slow decline in poverty that occurred over the expansion of the 1980s. We present evidence on the "stickiness" in the poverty rate in the past decade, compared to earlier decades. The following section investigates several potential non-earnings-related explanations for this fact. There is little evidence that the slowdown in the response of poverty to economic growth is due to problems with the measurement of poverty, to changes in transfer policy in the early 1980s, to the regional distribution of the poor during the 1980s expansion, or to changes in family composition among the poor. The final section of the paper investigated the decreased responsiveness of income and earnings to the rnacroeconomy among low-income households in the 1980s. A growing body of literature has recently began to explore the widening in wage differentials among less-skilled and more skilled workers over the 1980s.1 That literature indicates that substantial real wage declines occurred among low-wage workers throughout the expansion of the 1980s, while substantial real wage increases occurred among higher-wage workers. These trends are clearly correlated with the trends in poverty. Declining real wages will make it harder for low-income families to escape poverty. The point of this paper is not to describe that wage decline further, but to investigate how important this decline was relative to other factors that were operating at the bottom of the income distribution. The lower responsiveness of poverty to economic growth is not due changes in labor market responsiveness over the 1980s expansion. In fact, labor market involvement was more responsive during the 1980s: the unemployment rate fell more rapidly, and earners in the bottom quintile of the population increased their work effort more sharply in the 1980s than in the 1960s. The lower responsiveness of income among low-income households to the economic expansion of the 1980s is entirely due to declining real wages, which offset the increase in labor market effort, resulting in slower income growth. The implication of these results is that the changing wage structure of the l980s made economic growth a far less effective it was in the expansion of the 1960s. It is still an open question whether these trends will continue into the l990s. If they do, economic growth cannot be expected to produce substantial declines in the poverty rate.
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
FIGURE 4 in Trachelus stipa (Hymenoptera: Cephidae), a new stem sawfly from Central Anatolia associated with feather grass (Stipa holosericea, Poaceae)
No full textFIGURE 4. Claw of hind leg in female: A. Trachelus stipa; B. T. troglodyta; C. T. iudaicus; D. T libanensis; E. T. tabidus.Published as part of Budak, Mahir, Blank, Stephan M. & Başibüyük, Hasan H., 2017, Trachelus stipa (Hymenoptera: Cephidae), a new stem sawfly from Central Anatolia associated with feather grass (Stipa holosericea, Poaceae), pp. 99-110 in Zootaxa 4277 (1) on page 105, DOI: 10.11646/zootaxa.4277.1.7, http://zenodo.org/record/80910
NbN-MgO-NbN tunnel junctions integrated in aluminum strip lines for terahertz quasiparticle mixers
No full textNbN tunnel junctions are of great interest for THz heterodyne receivers because their large gap voltage of V-gap approximate to 5 mV implies an upper frequency limit of 4 Delta/h approximate to 2.6 THz as compared to 1.4 THz of Nb. However, due to the high ac losses in NbN films for frequencies above the NbN gap frequency, 2 Delta/h approximate to 1.3 THz, NbN matching circuits cannot be used. Lower losses are achieved with normal metals such as Al. Both for waveguide mixers and quasioptical mixers, quartz substrates are preferred. We report on a room-temperature fabrication process for NbN-MgO-NbN junctions with surfaces below 1 mu m(2) integrated in Al strip lines on quartz substrates. Appropriate plasma conditions for NbN-film deposition are obtained through the use of a second Nb target which acts as a selective nitrogen pump. NbN films on quartz substrates with and without an intermediate layer of Al have T-c > 15 K and rho(N) = 100 - 130 mu Omega.cm. Nb buffers should prevent the possible formation of insulating AIN at the Al-NbN interfaces. We fabricated the first NbN junctions sandwiched between Al layers. Sputtered Al were employed. Critical-current densities of up to 60 kA/cm(2) and subgap resistances R-sg approximate to 5.R-N were achieved. The I-V curves show various structures below the gap voltage. We discuss here the observation of a distinct steep step at eV = 2 Delta/3.</p
Fig. 12 in Big and beautiful: the Megaxyela species (Hymenoptera, Xyelidae) of East Asia and North America
No full textFig. 12. Species of Megaxyela Ashmead, 1898, ovipositors. A. M. euchroma Blank, Shinohara & Wei sp. nov., paratype, DEI-GISHym 22510 (NSMT). B–C. M. fulvago Blank, Shinohara & Wei sp. nov., paratype (5752, NSMT). C. Complete valvula 2 (incident light) and tip of valvula 2 (insert, transmitted light). D. M. inversa Blank & D.R. Smith sp. nov., paratype (22356, USNM). E. M. gigantea Mocsáry, 1909, holotype of M. mikado Sato, 1930 (22350, NSMT). F. M. parki Shinohara, 1992, paratype (18510, NSMT). G. M. pulchra Blank, Shinohara & Sundukov sp. nov., paratype (22348, NSMT). H. M. togashii Shinohara, 1992 (22353, NSMT). The images in B and H have been flipped horizontally.Published as part of Stephan M. Blank, Katja Kramp, David R. Smith, Yuri N. Sundukov, Meicai Wei & Akihiko Shinohara, 2017, Big and beautiful: the Megaxyela species (Hymenoptera, Xyelidae) of East Asia and North America, pp. 1-46 in European Journal of Taxonomy 348 on page 38, DOI: 10.5852/ejt.2017.348, http://zenodo.org/record/104266
Mesophilic-hydrothermal-thermophilic (M-H-T) digestion of green corn straw
No full textMesophilic-hydrothermal (80-160 degrees C, 30 min)-thermophilic (M-H-T) digestion and control tests of mesophilic (M), thermophilic (T), hydrothermal-mesophilic (H-M), and mesophilic-thermophilic digestion (M-T) of green corn straw were conducted for a 20-day fermentation period. The results indicate that M-H-T is an efficient method to improve methane production. A maximum methane yield of 371.74 mL/g volatile solid was obtained by the M (3 days)-H (140 degrees C)-T (17 days) process, which was 20.44%, 16.55%, 31.44%, and 14.31% higher than the yields of the M, T, 140-M, and M-T processes. The enhanced methane production was attributed to (1) the improved hemicellulose degradation and lignin disorganization; (2) prevention of the degradation of soluble sugar, easily hydrolyzed hemicellulose and cellulose into furfural and methylfurfural; and (3) lack of formation of Maillard reaction products during initial hydrothermal treatment. (C) 2015 Elsevier Ltd. All rights reserved
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