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We apply two methods to estimate the 21-cm bispectrum from data taken within the Epoch of Reionisation (EoR) project of the Murchison Widefield Array (MWA). Using data acquired with the Phase II compact array allows a direct bispectrum estimate to be undertaken on the multiple redundantly spaced triangles of antenna tiles, as well as an estimate based on data gridded to the uv-plane. The direct and gridded bispectrum estimators are applied to 21 h of high-band (167–197 MHz; z = 6.2–7.5) data from the 2016 and 2017 observing seasons. Analytic predictions for the bispectrum bias and variance for point-source foregrounds are derived. We compare the output of these approaches, the foreground contribution to the signal, and future prospects for measuring the bispectra with redundant and non-redundant arrays. We find that some triangle configurations yield bispectrum estimates that are consistent with the expected noise level after 10 h, while equilateral configurations are strongly foreground-dominated. Careful choice of triangle configurations may be made to reduce foreground bias that hinders power spectrum estimators, and the 21-cm bispectrum may be accessible in less time than the 21-cm power spectrum for some wave modes, with detections in hundreds of hours.
The second-order structure functions (SFs) of the velocity field, which characterize the velocity difference at two points, are widely used in research into non-reacting turbulent flows. In the present paper, the approach is extended in order to study the influence of combustion-induced thermal expansion on turbulent flow within a premixed flame brush. For this purpose, SFs conditioned to various combinations of mixture states at two different points (reactant–reactant, reactant–product, product–product, etc.) are introduced in the paper and a relevant exact transport equation is derived in the appendix. Subsequently, in order to demonstrate the capabilities of the newly developed approach for advancing the understanding of turbulent reacting flows, the conditioned SFs are extracted from three-dimensional (3-D) direct numerical simulation data obtained from two statistically 1-D planar, fully developed, weakly turbulent, premixed, single-step-chemistry flames characterized by significantly different (7.53 and 2.50) density ratios, with all other things being approximately equal. Obtained results show that the conditioned SFs differ significantly from standard mean SFs and convey a large amount of important information on various local phenomena that stem from the influence of combustion-induced thermal expansion on turbulent flow. In particular, the conditioned SFs not only (i) indicate a number of already known local phenomena discussed in the paper, but also (ii) reveal a less recognized phenomenon such as substantial influence of combustion-induced thermal expansion on turbulence in constant-density unburned reactants and even (iii) allow us to detect a new phenomenon such as the appearance of strong local velocity perturbations (shear layers) within flamelets. Moreover, SFs conditioned to heat-release zones indicate a highly anisotropic influence of combustion-induced thermal expansion on the evolution of small-scale two-point velocity differences within flamelets, with the effects being opposite (an increase or a decrease) for different components of the local velocity vector.
Most position sensitive proportional counters (PSPCs) currently used in X-ray diffraction experiments have a dead time longer than 5 μs. Though such PSPCs are useful in measuring weak diffraction diagrams, a faster counter is needed to detect strong X-ray diagrams produced with synchrotron radiation sources. The long dead time of PSPCs using a charge division position read-out is due to the slow analog division circuit plus analog-to-digital converter employed in the present system. A fast processor can be built utilising two high-speed ADCs to digitize voltage signals from the detector, followed by a digital divider to compute position of detected photons. The present paper describes the design of such a processor and some preliminary testings of its performances.
Dog treats might be contaminated with Salmonella. In Canada and the USA, outbreaks of human salmonellosis related to exposure to animal-derived dog treats were reported. Consequently, surveillance data on Salmonella contamination of dog treats have been gathered in many countries, but not in Japan. In the current study, we investigated whether dog treats in Japan were contaminated with Salmonella. Overall, 303 dog treats (of which 255 were domestically produced) were randomly collected and the presence of Salmonella investigated. Seven samples were positive for Salmonella enterica subsp. enterica. Among these isolates, three were identified as serovar 4,5,12:i:–; two were serovar Rissen; and two were serovar Thompson. All serovar 4,5,12:i:– and Thompson isolates were resistant to one or more drugs. Two serovar Rissen isolates were fully susceptible to all tested antimicrobial agents. All Salmonella isolates were susceptible to cefotaxime, ciprofloxacin and nalidixic acid. The gene blaTEM was detected in two serovar 4,5,12:i:– isolates. The blaCTX−M and blaCMY genes were not detected in any isolates. This study demonstrated that dog treats in Japan could constitute a potential source of dog and human Salmonella infections, including multidrug-resistant Salmonella isolates.
Recently, an epoch-making printing technology called “SuPR-NaP (Surface Photo-Reactive Nanometal Printing)” that allows easy, high-speed, and large-area manufacturing of ultrafine silver wiring patterns has been developed. Here we demonstrate low-voltage operation of organic thin-film transistors (OTFTs) composed of printed source/drain electrodes that are produced by the SuPR-NaP technique. We utilize an ultrathin layer of perfluoropolymer, Cytop, that functions not only as a base layer for producing patterned reactive surface in the SuPR-NaP technique but also as an ultrathin gate dielectric layer of OTFTs. By the use of 22 nm-thick Cytop gate dielectric layer, we successfully operate polycrystalline pentacene OTFTs below 2 V with negligible hysteresis. We also observe the improvement of carrier injection by the surface modification of printed silver electrodes. We discuss that the SuPR-NaP technique allows the production of high-capacitance gate dielectric layers as well as high-resolution printed silver electrodes, which provides promising bases for producing practical active-matrix OTFT backplanes.
We have made HCO+ (J = 1-0), HCN (J = 1-0) and CS (J = 2-1) observations of a bipolar flow source GL490 (Lada and Harvey 1981; Snell et al. 1984) using the Nobeyama 45-m telescope with 20″ resolution. A HCO+ spectrum obtained toward a central infrared source (Harvey et al. 1979) has prominent line wings extending up to 15-25 km s−1 from the line center (Figure 1). Figure 2 shows a map of HCO+ high velocity emission more than 8 km s−1 off the line center. The emission has “head-tail”-structures in both the blue- and the red-shifted sides; a “head” with stronger emission and a “tail” with weaker narrow ridge emission extending to the opposite side of the “head” through the center. The “head” emission has the same bipolar structure as the CO flow. Intermediate velocity emission at 38 km s−1 from the line center shows (1) a narrow ridge elongated in the NE-SW direction, at the blue-shifted side, and (2) a pair of shell-like structures symmetrically placed SW and NE of the center of the high velocity emission, at the red-shifted side (Figure 3).
Observations of the structure and the velocity field in the L1551 bipolar flow were made with the 45m telescope at Nobeyama in the 115GHz 12CO J = 1 – 0 line with high spatial resolution. It was found that the bipolar flow lobes have a clear hollow cylindrical structure and show evidence of a helical velocity field. They appear to rotate in the same direction as the CS disk found by Kaifu et al. (1984). The velocity of the flow in the bipolar directions increases with distance up to ∼ 3′ from the central object, IRS 5. These characteristics coincide with those predicted by the magnetodynamic theory proposed by Uchida and Shibata and indicate the essential importance of the magnetic field in producing such flows and also in the star-formation process itself through the enhancement of angular-momentum loss.
The maser emission of the J = 1-0 lines of SiO in vibrationally excited states has been detected in two regions of massive star formation, W51 IRS2 and Sgr B2 MD5. The SiO masers apparently coincide with strong H2O masers in each source within the uncertainties of < 5″. Their velocity ranges fall within those of the nearest H2O masers (Figure 1). In W51 IRS2 the maser emission is observed only in the v = 2 state, and the upper limit of the v = 1 line (3σ) is 1/15th of the v = 2 line intensity. The v = 1 emission found in Sgr B2 MD5 is five times stronger than the marginally detected v = 2 emission (Figure 2). Their luminosities are comparable to those from the corresponding maser in Orion.
We have made 15″ resolution observations of CO J = 1-0 emission toward L723 and S140 using the Nobeyama 45-m radio telescope. The maps resolved the molecular flow structures clearly. The outflow in the S140 molecular cloud was resolved to be a bipolar structure with its axis being nearly perpendicular to the elongation of the dense core observed in CS emission and to the direction of the infrared polarization. The blueshifted and redshifted components in L723 were resolved into two pairs of bipolar outflows with a point-symmetric structure.
We report NH3 observations of the Sgr A complex region including Sgr A West and the 20 km/s and 50 km/s molecular clouds (M–0.13–0.08 and M–0.02–0.07) using the Nobeyama Millimeter Array and the 45m telescope. NH3(1,1) and (2,2) lines were simultaneously observed to estimate the kinetic temperature. Our results suggest strong interaction between the molecular clouds and the continuum sources in the Sgr A complex. The interaction with continuum sources might be an important factor in determining the physical conditions of molecular gas in the galactic center region.
Here we discuss requirements for high performance and solution processable organic semiconductors, by presenting a systematic investigation of 7-alkyl-2-phenylbenzothieno[3,2-b]benzothiophenes (Ph-BTBT-Cn’s). We found that the solubility and thermal properties of Ph-BTBT-Cn’s depend systematically on the substituted alkyl-chain length n. The observed features are well understood in terms of the change of molecular packing motif with n: The compounds with n ≤ 4 do not form independent alkyl chain layers, whereas those with n ≥ 5 form isolated alkyl chain layers. The latter compounds afford a series of isomorphous bilayer-type crystal structures that form two-dimensional carrier transport layers within the crystals. We also show that the Ph-BTBT-C10 afford high performance single-crystalline field-effect transistors the mobility of which reaches as high as 15.9 cm2/Vs. These results demonstrate a crucial role of the substituted alkyl chain length for obtaining high performance organic semiconductors and field-effect transistors.
To address its temperature and density we made observations of the galactic plane in CO (2-1) line with VST1 and VST2. Using a kinetic model we estimate the volume emissivities and the line intensity ratio as a function of galactocentric radius. Using data in the first and 4th quadrants separately we got shallow gradient in the both quadrants; at the smaller radius is the higher in ratio. The gradient is contributed by less bright pixels in the l-v diagram, suggesting molecular gas in interarm is different along the galactocentric radius but in arm is not.
Physical conditions of molecular gas are key parameters to the formation rate and initial mass function of stars formed in molecular clouds. The ongoing Tokyo-NRO survey has been observing the Galactic CO (J=2–1) emission with a beamsize matched to the Columbia CO (J=1–0) survey. Intensities of the two lines should reflect physical conditions of the CO-emitting gas. An out-of-plane survey of the inner Galaxy which covers from 20° to 60° in galactic longitude and from −1° to +1° in galactic latitude with grid spacings of 0.25° has already been made (Sakamoto et al. 1994). Its coverage is large enough to draw conclusions on global properties of molecular gas in the inner Galaxy.
We report Hα imaging observations of nearby galaxies with the Kiso Schmidt telescope. For spiral galaxy NGC 628, we found no clear correlation between Hα and CO intensities, and we discuss the star formation efficiency of this galaxy. No nuclear Hα emission in this galaxy was detected. This is consistent with spectroscopic observations which indicate that the nuclear region is in the post starburst phase. We also describe the Hα image of Hickson's compact group 92 in which diffuse emission is detected extending within the group system.
As before a number of authors have contributed reviews of their own field. The contributions were editted by the President in order to avoid some overlaps, to reduce the length of the reviews and to add some publications. Reference numbers from “Astronomy and Astrophysics Abstracts” were used when available. In the end of the report a list of references not found in “Abstracts” is given. As editor, the President takes the responsibility for any shortcomings in the report.
Infared polarimetric and photometric mapping observations at K(2.2 μm) and H(1.65 μm) have revealed an extended dust envelope around the late-type star IRC+10216. The observations were made on the 3.8-m United Kingdom Infrared Telescope on Mauna Kea, Hawaii, in 1985 December and 1987 January and February. The polarization observations were made by emplying the Kyoto polarimeter (Sato et al. 1987). Great care was taken to check the contamination by stray light in the telescope and instruments as the source on peak was extremely bright (K~0 mag). From the observations of normal stars, we found that the polarized intensity (degree of polarization times the intensity) was a good measure of the envelope, free from contamination by stray light, although the intensity and the degree of polarization suffered from the contamination separately.
We have made aperture synthesis observations of CS(J=l-0, 2-1) and NH3(1,1) lines and 49, 98, and 110 GHz continuum in NGC2071-1RS with the Nobeyama Millimeter Array. Wfe have obtained maps of these lines and continuum maps with 2”. 7-20” resolution, ffe have found that dense molecular gas has a disk structure with a radial scale ranging 0.01 pc - 0.1 pc and has a ring-like structure with expanding motion at the central 5000 AU region. We also have found that there exists double dust continuum sources which are separated by 2500 AU in projection and are apparently located at the inner edges of the ring. Our observational results suggest that the disk of molecular gas has a central hole formed by wind and UV radiation from a central young stellar object, the central part is expanding, and that dust continuum emission comes from tangential parts of the shock compressed ring (r~1300 AU, M(H2)~ 21-34 Mo, and n(H2)~ 109) at the most inner side of the disk structure. The other possible model of the dust continuum sources is a binary system of self-luminous young stellar objects.
Short lasting flashes, called as First Precursor (PC1), were observed by some ground-based near-infrared observations for the impacts of large-sized fragments of comet Shoemaker-Levy 9 (SL9) in July 1994. The impact detections by the spacecraft Galileo [2, 7] about 10 seconds after the PC1 detections by ground based telescopes, combined with the far-side impacts of SL9 fragments as viewed from Earth, suggest that the source of the PC1 should be located in the Jovian upper atmosphere above the limb, at which the atmospheric pressure is extremely low. Thus, an important problem on the PC1 is how does the falling cometary fragment, which is a huge meteorite, emit near-infrared in the extremely thin atmosphere. The ablation model, which is usually used for an impact bolide, can only estimate flux from the bolide in a dense atmosphere at visible wavelength. In this paper, we assume that the PC1s are thermal radiation from the fragments and attempt quantitative estimations of the PCI fluxes using a simple entry flash model.
Polymeric nanoparticles having redox-active catechol moieties, a common structural motif found in naturally-occurring antioxidants, were developed. We synthesized an amphiphilic catechol-bearing polymer that self-assembled to form nanoparticles with a diameter of 126 nm. The nanoparticles showed enhanced ROS-scavenging activity compared to the small catecholic compound dopamine. Furthermore, the nanoparticles inhibited ROS-mediated angiogenesis as shown by the endothelial cell tube formation assay and the chicken chorioallantoic membrane (CAM) assay.