5,048 research outputs found
Measuring the muon's anomalous magnetic moment to 0.14 ppm
The anomalous magnetic moment (g-2) of the muon was measured with a precision
of 0.54 ppm in Experiment 821 at Brookhaven National Laboratory. A difference
of 3.2 standard deviations between this experimental value and the prediction
of the Standard Model has persisted since 2004; in spite of considerable
experimental and theoretical effort, there is no consistent explanation for
this difference. This comparison hints at physics beyond the Standard Model,
but it also imposes strong constraints on those possibilities, which include
supersymmetry and extra dimensions. The collaboration is preparing to relocate
the experiment to Fermilab to continue towards a proposed precision of 0.14
ppm. This will require 20 times more recorded decays than in the previous
measurement, with corresponding improvements in the systematic uncertainties.
We describe the theoretical developments and the experimental upgrades that
provide a compelling motivation for the new measurement.Comment: 5 pages, 1 figure, presented at International Nuclear Physics
Conference 2010 (INPC 2010
Is the Sun Lighter than the Earth? Isotopic CO in the Photosphere, Viewed through the Lens of 3D Spectrum Synthesis
We consider the formation of solar infrared (2-6 micron) rovibrational bands
of carbon monoxide (CO) in CO5BOLD 3D convection models, with the aim to refine
abundances of the heavy isotopes of carbon (13C) and oxygen (18O,17O), to
compare with direct capture measurements of solar wind light ions by the
Genesis Discovery Mission. We find that previous, mainly 1D, analyses were
systematically biased toward lower isotopic ratios (e.g., R23= 12C/13C),
suggesting an isotopically "heavy" Sun contrary to accepted fractionation
processes thought to have operated in the primitive solar nebula. The new 3D
ratios for 13C and 18O are: R23= 91.4 +/- 1.3 (Rsun= 89.2); and R68= 511 +/- 10
(Rsun= 499), where the uncertainties are 1 sigma and "optimistic." We also
obtained R67= 2738 +/- 118 (Rsun= 2632), but we caution that the observed
12C17O features are extremely weak. The new solar ratios for the oxygen
isotopes fall between the terrestrial values and those reported by Genesis
(R68= 530, R6= 2798), although including both within 2 sigma error flags, and
go in the direction favoring recent theories for the oxygen isotope composition
of Ca-Al inclusions (CAI) in primitive meteorites. While not a major focus of
this work, we derive an oxygen abundance of 603 +/- 9 ppm (relative to
hydrogen; 8.78 on the logarithmic H= 12 scale). That the Sun likely is lighter
than the Earth, isotopically speaking, removes the necessity to invoke exotic
fractionation processes during the early construction of the inner solar
system
The Mg 2 h and k lines in a sample of dMe and dM stars
Both Mg II h and k line fluxes are presented for a sample of 4 dMe and 3 dM stars obtained with the IUE satellite in the long wavelength, low dispersion mode. The observed fluxes are converted to stellar surface flux units and the importance of chromospheric non radiative heating in this sample of M dwarf stars is intercompared. In addition, the net chromospheric radiative losses due to the Ca II H and K lines in those stars in the sample for which calibrated Ca II H and K line data exist are compared. Active region filling factors which likely give rise to the observed optical and ultraviolet chromospheric emission are estimated. The implications of the results for homogeneous, single component stellar model chromospheres analyses are discussed
Hydrography and Hydrodynamics of Virginia Estuaries: Dye Tracer Study and Elizabeth River System
The paper notes that the success of economic policy aimed at forming a new model of Ukraine's economic growth is facilitated by a clear choice of priorities, among which the main thing is to ensure high rates of sustainable economic growth.
The main components of the innovative environment of the economy are determined. The analysis of indicators of innovative development of the countries of the world for the period 2011–2017 is carried out using the Principal Components and Classification Analysis method in the Statistica 10.0 software package. The factors of influence on the innovative development of countries are determined. The advantages of structuring the innovative environment are determination of the subordination of priorities for supporting innovations by the state, business and financial market.
In the course of the research, methods of systemic, theoretical generalization, analysis, comparative comparison, tabular and graphical presentation of results are used, which allows the author to prove a low level of regulation of the innovation process characteristic of the Ukrainian economy. The problems of innovative development of groups of countries with low and above average level of income according to the World Bank classification are characterized by the lack of a developed innovative environment, the implementation of the secondary role of the state as a component of the national innovative system.
The peculiarity of state regulation of high-income countries is determined by the balance of innovation policy instruments. The presence of a developed institutional environment (fundamental conditions) ensures the effectiveness of financial support of the business, obtaining high results from innovations and retaining the leading position on innovative development.
At the decision of the enterprises of a group of countries with a level of incomes above the average for the implementation of investments in innovative activities and further innovative development, financial markets, commodity markets and the effectiveness of the legal system are of greatest importance. It is proved that for the low-income countries the variable "Market development" has a stimulating significance for economic growth.
The above, as well as fragmentation, the definition of factors of innovative development according to the Global Innovation Index, provided grounds for the author to give recommendations (integral indicator) in determining the priority of development of the content elements of the national innovative system, highlighting the importance of the state, human capital, research, financial and commodity markets in economic growth of the country, identifying sources and priorities for financing innovative development
Viscoelastic response of sonic band-gap materials
A brief report is presented on the effect of viscoelastic losses in a high
density contrast sonic band-gap material of close-packed rubber spheres in air.
The scattering properties of such a material are computed with an on-shell
multiple scattering method, properties which are compared with the lossless
case. The existence of an appreciable omnidirectional gap in the transmission
spectrum, when losses are present, is also reported.Comment: 5 pages, 4 figures, submitted to PR
FK Comae Berenices, King of Spin: The COCOA-PUFS Project
COCOA-PUFS is an energy-diverse, time-domain study of the ultra-fast
spinning, heavily spotted, yellow giant FK Com (HD117555; G4 III). This single
star is thought to be a recent binary merger, and is exceptionally active by
measure of its intense ultraviolet and X-ray emissions, and proclivity to
flare. COCOA-PUFS was carried out with Hubble Space Telescope in the UV
(120-300 nm), using mainly its high-performance Cosmic Origins Spectrograph,
but also high-precision Space Telescope Imaging Spectrograph; Chandra X-ray
Observatory in the soft X-rays (0.5-10 keV), utilizing its High-Energy
Transmission Grating Spectrometer; together with supporting photometry and
spectropolarimetry in the visible from the ground. This is an introductory
report on the project.
FK Com displayed variability on a wide range of time scales, over all
wavelengths, during the week-long main campaign, including a large X-ray flare;
"super-rotational broadening" of the far-ultraviolet "hot-lines" (e.g., Si IV
139 nm (T~80,000 K) together with chromospheric Mg II 280 nm and C II 133 nm
(10,000-30,000 K); large Doppler swings suggestive of bright regions
alternately on advancing and retreating limbs of the star; and substantial
redshifts of the epoch-average emission profiles. These behaviors paint a
picture of a highly extended, dynamic, hot (10 MK) coronal magnetosphere around
the star, threaded by cooler structures perhaps analogous to solar prominences,
and replenished continually by surface activity and flares. Suppression of
angular momentum loss by the confining magnetosphere could temporarily postpone
the inevitable stellar spindown, thereby lengthening this highly volatile stage
of coronal evolution.Comment: to be published in ApJ
Acceptability of, and barriers and facilitators to, a pilot physical health service for people who inject drugs: A qualitative study with service users and providers
BACKGROUND: People who inject drugs may experience difficulty accessing or maintaining involvement with traditional healthcare services. This is associated with increased health inequalities and bio-psychosocial difficulties. Embedding physical healthcare services within community-based drug services may provide a practical and feasible approach to increase access and delivery of healthcare. This study explored the acceptability of, and barriers and facilitators to, embedding a pilot physical healthcare service within a community-based drug service in the United Kingdom (Bristol, England). METHODS: Semi-structured interviews were conducted with service users (people who inject drugs) (n = 13), and a focus group was conducted with service providers (n = 11: nine harm reduction workers, two nurses, one service manager). Topic guides included questions to explore barriers and facilitators to using and delivering the service (based on the COM-B Model), and acceptability of the service (using the Theoretical Framework of Acceptability). Transcripts were analysed using a combined deductive framework and inductive thematic analysis approach. RESULTS: The service was viewed as highly acceptable. Service users and providers were confident they could access and provide the service respectively, and perceived it to be effective. Barriers included competing priorities of service users (e.g. drug use) and the wider service (e.g. equipment), and the potential impact of the service being removed in future was viewed as a barrier to overall healthcare access. Both service users and providers viewed embedding the physical health service within an existing community-based drug service as facilitating accessible and holistic care which reduced stigma and discrimination. CONCLUSIONS: The current study demonstrated embedding a physical health service within an existing community-drug based and alcohol service was acceptable and beneficial. Future studies are required to demonstrate cost-effectiveness and ensure long-term sustainability, and to determine transferability of findings to other settings, organisations and countries
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