Anisotropic dynamics of charge carriers in graphene

Má,rk, Gé,za I.,Vancsó,, Pé,ter,Hwang, Chanyong,Lambin, Philippe,Biró,, L&aacute,szló,P. American Physical Society 2012 Physical review. B, Condensed matter and materials Vol.85 No.12

Final report on key comparison CCQM-K96: Determination of amount content of dichromate

Má,ri&aacute,ssy, Michal,Hankov&aacute,, Zuzana,Hwang, Euijin,Lim, Youngran,Pratt, Kenneth W,Hioki, Akiharu,Asakai, Toshiaki,Bing, Wu,Liandi, Ma,Chao, Wei,Sobina, Alena,Shimolin, Alexandr,Junior Springer-Verlag 2013 METROLOGIA -BERLIN- Vol.50 No.-

<P>The key comparison CCQM-K96 was organized jointly by the inorganic and electrochemistry working groups of CCQM to test the abilities of the metrology institutes to measure the amount content of dichromate. Slovak Institute of Metrology with help of KRISS acted as the coordinating laboratories. Eight NMIs took part in the comparison. All participants used high accuracy constant current coulometry. Good agreement of the results was observed.</P><P>Main text.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.</P><P>The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).</P>

Infall Signatures in a Prestellar Core Embedded in the High-mass 70 <i>μ</i>m Dark IRDC G331.372-00.116

Contreras, Yanett,Sanhueza, Patricio,Jackson, James M.,Guzmá,n, André,s E.,Longmore, Steven,Garay, Guido,Zhang, Qizhou,Nguyê,̃,n-Lu’o’, Quang,Tatematsu, Ken’ichi,Nakamura, Fumita American Astronomical Society 2018 The Astrophysical journal Vol.861 No.1

<P>Using Galactic Plane surveys, we have selected a massive (1200M circle dot), cold (14 K) 3.6-70 mu m dark IRDC, G331.372-00.116. This infrared dark cloud (IRDC) has the potential to form high-mass stars, and given the absence of current star formation signatures, it seems to represent the earliest stages of high-mass star formation. We have mapped the whole IRDC with the Atacama Large Millimeter/submillimeter Array (ALMA) at 1.1 and 1.3 mm in dust continuum and line emission. The dust continuum reveals 22 cores distributed across the IRDC. In this work, we analyze the physical properties of the most massive core, ALMA1, which has no molecular outflows detected in the CO (2-1), SiO (5-4), and H2CO (3-2) lines. This core is relatively massive (M = 17.6M circle dot), subvirialized (virial parameter alpha(vir) = M-vir/M = 0.14), and is barely affected by turbulence (transonic Mach number of 1.2). Using the HCO+ (3-2) line, we find the first detection of infall signatures in a relatively massive, prestellar core (ALMA1) with the potential to form a high-mass star. We estimate an infall speed of 1.54 km s(-1) and a high accretion rate of 1.96. x. 10(-3) M circle dot yr(-1). ALMA1 is rapidly collapsing, out of virial equilibrium, which is more consistent with competitive accretion scenarios rather than the turbulent core accretion model. On the other hand, ALMA1 has a mass similar to 6 times larger than the clumps Jeans mass, as it is in an intermediate mass regime (M-J = 2.7 < M less than or similar to 30 M circle dot), contrary to what both the competitive accretion and turbulent core accretion theories predict.</P>

Size-resolved cloud condensation nuclei concentration measurements in the Arctic: two case studies from the summer of 2008

Z&aacute,bori, J.,Rastak, N.,Yoon, Y. J.,Riipinen, I.,Strö,m, J. Copernicus GmbH 2015 Atmospheric Chemistry and Physics Vol.15 No.23

<P>Abstract. The Arctic is one of the most vulnerable regions affected by climate change. Extensive measurement data are needed to understand the atmospheric processes governing this vulnerability. Among these, data describing cloud formation potential are of particular interest, since the indirect effect of aerosols on the climate system is still poorly understood. In this paper we present, for the first time, size-resolved cloud condensation nuclei (CCN) data obtained in the Arctic. The measurements were conducted during two periods in the summer of 2008: one in June and one in August, at the Zeppelin research station (78°54´ N, 11°53´ E) in Svalbard. Trajectory analysis indicates that during the measurement period in June 2008, air masses predominantly originated from the Arctic, whereas the measurements from August 2008 were influenced by mid-latitude air masses. CCN supersaturation (SS) spectra obtained on the 27 June, before size-resolved measurements were begun, and spectra from the 21 and 24 August, conducted before and after the measurement period, revealed similarities between the 2 months. From the ratio between CCN concentration and the total particle number concentration (CN) as a function of dry particle diameter (Dp) at a SS of 0.4 %, the activation diameter (D50), corresponding to CCN / CN = 0.50, was estimated. D50 was found to be 60 and 67 nm for the examined periods in June and August 2008, respectively. Corresponding D50 hygroscopicity parameter (κ) values were estimated to be 0.4 and 0.3 for June and August 2008, respectively. These values can be compared to hygroscopicity values estimated from bulk chemical composition, where κ was calculated to be 0.5 for both June and August 2008. While the agreement between the 2 months is reasonable, the difference in κ between the different methods indicates a size dependence in the particle composition, which is likely explained by a higher fraction of inorganics in the bulk aerosol samples. </P>

Roadmap on optical sensors

Ferreira, Má,rio F S,Castro-Camus, Enrique,Ottaway, David J,Ló,pez-Higuera, José,Miguel,Feng, Xian,Jin, Wei,Jeong, Yoonchan,Picqué,, Nathalie,Tong, Limin,Reinhard, Bjö,rn M IOP 2017 Journal of optics Vol.19 No.8

<P>Sensors are devices or systems able to detect, measure and convert magnitudes from any domain to an electrical one. Using light as a probe for optical sensing is one of the most efficient approaches for this purpose. The history of optical sensing using some methods based on absorbance, emissive and florescence properties date back to the 16th century. The field of optical sensors evolved during the following centuries, but it did not achieve maturity until the demonstration of the first laser in 1960. The unique properties of laser light become particularly important in the case of laser-based sensors, whose operation is entirely based upon the direct detection of laser light itself, without relying on any additional mediating device. However, compared with freely propagating light beams, artificially engineered optical fields are in increasing demand for probing samples with very small sizes and/or weak light−matter interaction. Optical fiber sensors constitute a subarea of optical sensors in which fiber technologies are employed. Different types of specialty and photonic crystal fibers provide improved performance and novel sensing concepts. Actually, structurization with wavelength or subwavelength feature size appears as the most efficient way to enhance sensor sensitivity and its detection limit. This leads to the area of micro- and nano-engineered optical sensors. It is expected that the combination of better fabrication techniques and new physical effects may open new and fascinating opportunities in this area. This roadmap on optical sensors addresses different technologies and application areas of the field. Fourteen contributions authored by experts from both industry and academia provide insights into the current state-of-the-art and the challenges faced by researchers currently. Two sections of this paper provide an overview of laser-based and frequency comb-based sensors. Three sections address the area of optical fiber sensors, encompassing both conventional, specialty and photonic crystal fibers. Several other sections are dedicated to micro- and nano-engineered sensors, including whispering-gallery mode and plasmonic sensors. The uses of optical sensors in chemical, biological and biomedical areas are described in other sections. Different approaches required to satisfy applications at visible, infrared and THz spectral regions are also discussed. Advances in science and technology required to meet challenges faced in each of these areas are addressed, together with suggestions on how the field could evolve in the near future.</P>

Observing the onset of outflow collimation in a massive protostar

Carrasco-Gonz&aacute,lez, C.,Torrelles, J. M.,Cantó,, J.,Curiel, S.,Surcis, G.,Vlemmings, W. H. T.,van Langevelde, H. J.,Goddi, C.,Anglada, G.,Kim, S.-W.,Kim, J.-S.,Gó,mez, J. F. American Association for the Advancement of Scienc 2015 Science Vol.348 No.6230

<P><B>Young stars grow up and narrow their focus</B></P><P>Stars are thought to grow by gathering spirals of material from a disk. If this is the case, to balance angular momentum, gas should flow out rapidly along the disk's rotation axis. Carrasco-Gonzalez <I>et al.</I> now seem to have glimpsed the “before” and “after” stages of the onset of such an outflow, over the course of just 18 years (see the Perspective by Hoare). Radio monitoring of the massive protostar W75N(B)-VLA2 reveals a transition from a spherical wind to a collimated one, giving critical insight into what happens as a massive star forms.</P><P><I>Science</I>, this issue p. 114; see also p. 44</P><P>The current paradigm of star formation through accretion disks, and magnetohydrodynamically driven gas ejections, predicts the development of collimated outflows, rather than expansion without any preferential direction. We present radio continuum observations of the massive protostar W75N(B)-VLA 2, showing that it is a thermal, collimated ionized wind and that it has evolved in 18 years from a compact source into an elongated one. This is consistent with the evolution of the associated expanding water-vapor maser shell, which changed from a nearly circular morphology, tracing an almost isotropic outflow, to an elliptical one outlining collimated motions. We model this behavior in terms of an episodic, short-lived, originally isotropic ionized wind whose morphology evolves as it moves within a toroidal density stratification.</P>

The behaviour of ²³⁶U in the North Atlantic Ocean assessed from numerical modelling: A new evaluation of the input function into the Arctic

Peri&aacute,ñ,ez, R.,Suh, Kyung-Suk,Min, Byung-Il,Villa-Alfageme, M. Elsevier 2018 The Science of the total environment Vol.626 No.-

<P><B>Abstract</B></P> <P>A numerical model, previously validated with other radionuclides, was applied to simulate the dispersion of <SUP>236</SUP>U released from European nuclear fuel reprocessing plants in the North Atlantic and Shelf Seas using a published reconstruction of Sellafield and La Hague releases. Model results are in better agreement with observations if the lowest estimation of such releases are used. This implies that approximately 40kg of <SUP>236</SUP>U has been discharged from Sellafield. It was found that adsorption of <SUP>236</SUP>U on bed sediments of the shallow European Shelf Seas plays an essential role in its dispersion patterns. This contrasts strongly with the more conservative behaviour of <SUP>129</SUP>I in the same area. This has two important implications in the use of <SUP>236</SUP>U as oceanographic tracer; i) special care must be taken in coastal areas, as sediments might act as sinks and sources of <SUP>236</SUP>U; ii) the annual input function of <SUP>236</SUP>U into the Arctic is not directly controlled by the annual discharges from Sellafield and La Hague, since sediments from the Irish, Celtic and North Sea modulate and smooth the signal. Only 52% of the total releases enter into the Arctic Ocean.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Calculated <SUP>236</SUP>U concentrations in water and sediments compared with measurements. </LI> <LI> Adsorption of <SUP>236</SUP>U in bed sediments is significant. </LI> <LI> Releases from Sellafield estimated as 40kg of <SUP>236</SUP>U for period 1952–2013 </LI> <LI> Only 52% of the total releases from the three nuclear facilities are introduced into the Arctic. </LI> <LI> Input function into the Arctic reconstructed: total of 38 ± 8kg of <SUP>236</SUP>U for period 1952–2013. </LI> </UL> </P> <P><B>Graphical Abstract</B></P> <P>[DISPLAY OMISSION]</P>

Production of [FORMULA OMISSION] and [FORMULA OMISSION] in p–Pb collisions at [FORMULA OMISSION] TeV

Adamov&aacute,, D.,Aggarwal, M. M.,Aglieri Rinella, G.,Agnello, M.,Agrawal, N.,Ahammed, Z.,Ahmad, S.,Ahn, S. U.,Aiola, S.,Akindinov, A.,Alam, S. N.,Albuquerque, D. S. D.,Aleksandrov, D.,Alessandro, B. Springer 2017 European Physical Journal C Vol.77 No.6

<P>The transverse momentum distributions of the strange and double-strange hyperon resonances ([FORMULA OMISSION], [FORMULA OMISSION]) produced in p–Pb collisions at [FORMULA OMISSION] TeV were measured in the rapidity range [FORMULA OMISSION] for event classes corresponding to different charged-particle multiplicity densities, [FORMULA OMISSION]d[FORMULA OMISSION]/d[FORMULA OMISSION]. The mean transverse momentum values are presented as a function of [FORMULA OMISSION]d[FORMULA OMISSION]/d[FORMULA OMISSION], as well as a function of the particle masses and compared with previous results on hyperon production. The integrated yield ratios of excited to ground-state hyperons are constant as a function of [FORMULA OMISSION]d[FORMULA OMISSION]/d[FORMULA OMISSION]. The equivalent ratios to pions exhibit an increase with [FORMULA OMISSION]d[FORMULA OMISSION]/d[FORMULA OMISSION], depending on their strangeness content.</P>

HIGHEST REDSHIFT IMAGE OF NEUTRAL HYDROGEN IN EMISSION: A CHILES DETECTION OF A STARBURSTING GALAXY AT <i>z</i> = 0.376

Fern&aacute,ndez, Ximena,Gim, Hansung B.,Gorkom, J. H. van,Yun, Min S.,Momjian, Emmanuel,Popping, Attila,Chomiuk, Laura,Hess, Kelley M.,Hunt, Lucas,Kreckel, Kathryn,Lucero, Danielle,Maddox, Natasha,Oo American Astronomical Society 2016 ASTROPHYSICAL JOURNAL LETTERS - Vol.824 No.1

<P>Our current understanding of galaxy evolution still has many uncertainties associated with the details of the accretion, processing, and removal of gas across cosmic time. The next generation of radio telescopes will image the neutral hydrogen (H I) in galaxies over large volumes at high redshifts, which will provide key insights into these processes. We are conducting the COSMOS H I Large Extragalactic Survey (CHILES) with the Karl G. Jansky Very Large Array, which is the first survey to simultaneously observe H I from z = 0 to z similar to 0.5. Here, we report the highest redshift H I 21 cm detection in emission to date of the luminous infrared galaxy COSMOS J100054.83+023126.2 at z = 0.376 with the first 178 hr of CHILES data. The total H I mass is (2.9 +/- 1.0) x 10(10) M-circle dot and the spatial distribution is asymmetric and extends beyond the galaxy. While optically the galaxy looks undisturbed, the H I distribution suggests an interaction with a candidate companion. In addition, we present follow-up Large Millimeter Telescope CO observations that show it is rich in molecular hydrogen, with a range of possible masses of (1.8-9.9) x 10(10) M-circle dot. This is the first study of the H I and CO in emission for a single galaxy beyond z similar to 0.2.</P>

High-energy neutrino follow-up search of gravitational wave event GW150914 with ANTARES and IceCube

Adri&aacute,n-Martí,nez, S.,Albert, A.,André,, M.,Anghinolfi, M.,Anton, G.,Ardid, M.,Aubert, J.-J.,Avgitas, T.,Baret, B.,Barrios-Martí,, J.,Basa, S.,Bertin, V.,Biagi, S.,Bormuth, R. American Physical Society 2016 Physical Review D Vol.93 No.12

<P>We present the high-energy-neutrino follow-up observations of the first gravitational wave transient GW150914 observed by the Advanced LIGO detectors on September 14, 2015. We search for coincident neutrino candidates within the data recorded by the IceCube and ANTARES neutrino detectors. A possible joint detection could be used in targeted electromagnetic follow-up observations, given the significantly better angular resolution of neutrino events compared to gravitational waves. We find no neutrino candidates in both temporal and spatial coincidence with the gravitational wave event. Within +/- 500 s of the gravitational wave event, the number of neutrino candidates detected by IceCube and ANTARES were three and zero, respectively. This is consistent with the expected atmospheric background, and none of the neutrino candidates were directionally coincident with GW150914. We use this nondetection to constrain neutrino emission from the gravitational-wave event.</P>