12,542 research outputs found
Omreglering så att (nästan) alla blir vinnare
I denna artikel diskuterar vi några av de konflikter som råder kring vattenkraften. En omreglering sådan att i princip alla vinner presenteras. Förslaget tillämpas på Ljusnan där två dammar vid utloppet föreslås bli utrivna och kraftverksägaren kompenseras med en utbyggnad 15 mil uppströms. Lax och andra arter kan då vandra 15 mil uppströms för lek. Vidare förbättras rekreationsmöjligheterna för de kringboende
High-growth firms: introduction to the special section
High-growth firms (HGFs) have attracted considerable attention recently, as academics and policymakers have increasingly recognized the highly skewed nature of many metrics of firm performance. A small number of HGFs drives a disproportionately large amount of job creation, while the average firm has a limited impact on the economy. This article explores the reasons for this increased interest, summarizes the existing literature, and highlights the methodological considerations that constrain and bias research. This special section draws attention to the importance of HGFs for future industrial performance, explores their unusual growth trajectories and strategies, and highlights the lack of persistence of high growth. Consequently, while HGFs are important for understanding the economy and developing public policy, they are unlikely to be useful vehicles for public policy given the difficulties involved in predicting which firms will grow, the lack of persistence in high growth levels, and the complex and often indirect relationship between firm capability, high growth, and macro-economic performance
Coherent current transport in wide ballistic Josephson junctions
We present an experimental and theoretical investigation of coherent current
transport in wide ballistic superconductor-two dimensional electron
gas-superconductor junctions. It is found experimentally that upon increasing
the junction length, the subharmonic gap structure in the current-voltage
characteristics is shifted to lower voltages, and the excess current at
voltages much larger than the superconducting gap decreases. Applying a theory
of coherent multiple Andreev reflection, we show that these observations can be
explained in terms of transport through Andreev resonances.Comment: 4 pages, 4 figure
The FERRUM project: Transition probabilities for forbidden lines in [FeII] and experimental metastable lifetimes
Accurate transition probabilities for forbidden lines are important
diagnostic parameters for low-density astrophysical plasmas. In this paper we
present experimental atomic data for forbidden [FeII] transitions that are
observed as strong features in astrophysical spectra.
Aims: To measure lifetimes for the 3d^6(^3G)4s a ^4G_{11/2} and 3d^6(^3D)4s b
^4D_{1/2} metastable levels in FeII and experimental transition probabilities
for the forbidden transitions 3d^7 a ^4F_{7/2,9/2}- 3d^6(^3G)4s a ^4G_{11/2}.
Methods: The lifetimes were measured at the ion storage ring facility CRYRING
using a laser probing technique. Astrophysical branching fractions were
obtained from spectra of Eta Carinae, obtained with the Space Telescope Imaging
Spectrograph onboard the Hubble Space Telescope. The lifetimes and branching
fractions were combined to yield absolute transition probabilities.
Results: The lifetimes of the a ^4G_{11/2} and the b ^4D_{1/2} levels have
been measured and have the following values, 0.75(10) s and 0.54(3) s
respectively. Furthermore, we have determined the transition probabilities for
two forbidden transitions of a ^4F_{7/2,9/2}- a ^4G_{11/2} at 4243.97 and
4346.85 A. Both the lifetimes and the transition probabilities are compared to
calculated values in the literature.Comment: 5 pages, accepted for publication in A&
Internally Electrodynamic Particle Model: Its Experimental Basis and Its Predictions
The internally electrodynamic (IED) particle model was derived based on
overall experimental observations, with the IED process itself being built
directly on three experimental facts, a) electric charges present with all
material particles, b) an accelerated charge generates electromagnetic waves
according to Maxwell's equations and Planck energy equation and c) source
motion produces Doppler effect. A set of well-known basic particle equations
and properties become predictable based on first principles solutions for the
IED process; several key solutions achieved are outlined, including the de
Broglie phase wave, de Broglie relations, Schr\"odinger equation, mass,
Einstein mass-energy relation, Newton's law of gravity, single particle self
interference, and electromagnetic radiation and absorption; these equations and
properties have long been broadly experimentally validated or demonstrated. A
specific solution also predicts the Doebner-Goldin equation which emerges to
represent a form of long-sought quantum wave equation including gravity. A
critical review of the key experiments is given which suggests that the IED
process underlies the basic particle equations and properties not just
sufficiently but also necessarily.Comment: Presentation at the 27th Int Colloq on Group Theo Meth in Phys, 200
Palaeoproterozoic adakite- and TTG-like magmatism in the Svecofennian orogen, SW Finland
The Palaeoproterozoic Svecofennian orogen in the Fennoscandian shield is an arc accretionary orogen that was formed at c. 1.92-1.86Ga. Arc accretion, magmatism and the subsequent continent-continent collision thickened the crust up to c. 70km, forming one of the thickest Palaeoproterozic orogens. At the end stage of accretionary tectonics, voluminous synorogenic magmatism occurred in southwestern Finland leading to the intrusion of intermediate to felsic plutonic rocks. Ion microprobe single zircon dating of one diorite sample yielded an age of 1872±3Ma (εNd=+2.2) and the trondhjemite sample an age of 1867±4Ma (εNd=+2.6). Inherited 2667-1965Ma cores and 1842±5Ma metamorphic rims were also found in zircons from the trondhjemite. The dioritic magmatism is mantle-derived and is slightly enriched by subduction-related processes. The felsic magmatism shows elevated Sr/Y and La/Yb ratios, which are typical for adakite- and TTG-like magmas. Their low Mg#, Ni and Cr contents argue against slab-melting and mantle-wedge contamination. We infer that the felsic magmatism was generated through crustal melting of the lower part of the previously generated volcanic-arc type crust. Based on published melting experiments and the Sr and Y contents of the felsic rocks we suggest that the melts were generated at a minimum pressure of 10kbar, with evidence of a 15kbar pressure for the highest Sr/Y trondhjemites. It is proposed that arc accretion combined with magmatic intrusions thickened the crust so that melting of the lower crust yielded adakite- and TTG-like compositions. The mafic magmatism is considered to be the heat source
Coherent and sequential photoassisted tunneling through a semiconductor double barrier structure
We have studied the problem of coherent and sequential tunneling through a
double barrier structure, assisted by light considered to be present All over
the structure, i,e emitter, well and collector as in the experimental evidence.
By means of a canonical transformation and in the framework of the time
dependent perturbation theory, we have calculated the transmission coefficient
and the electronic resonant current. Our calculations have been compared with
experimental results turning out to be in good agreement. Also the effect on
the coherent tunneling of a magnetic field parallel to the current in the
presence of light, has been considered.Comment: Revtex3.0, 8figures uuencoded compressed tar-fil
Standardisation of magnetic nanoparticles in liquid suspension
Suspensions of magnetic nanoparticles offer diverse opportunities for technology innovation, spanning a large number of industry sectors from imaging and actuation based applications in biomedicine and biotechnology, through large-scale environmental remediation uses such as water purification, to engineering-based applications such as position-controlled lubricants and soaps. Continuous advances in their manufacture have produced an ever-growing range of products, each with their own unique properties. At the same time, the characterisation of magnetic nanoparticles is often complex, and expert knowledge is needed to correctly interpret the measurement data. In many cases, the stringent requirements of the end-user technologies dictate that magnetic nanoparticle products should be clearly defined, well characterised, consistent and safe; or to put it another way—standardised. The aims of this document are to outline the concepts and terminology necessary for discussion of magnetic nanoparticles, to examine the current state-of-the-art in characterisation methods necessary for the most prominent applications of magnetic nanoparticle suspensions, to suggest a possible structure for the future development of standardisation within the field, and to identify areas and topics which deserve to be the focus of future work items. We discuss potential roadmaps for the future standardisation of this developing industry, and the likely challenges to be encountered along the way
A quantitative central limit theorem for linear statistics of random matrix eigenvalues
It is known that the fluctuations of suitable linear statistics of Haar
distributed elements of the compact classical groups satisfy a central limit
theorem. We show that if the corresponding test functions are sufficiently
smooth, a rate of convergence of order almost can be obtained using a
quantitative multivariate CLT for traces of powers that was recently proven
using Stein's method of exchangeable pairs.Comment: Title modified; main result stated under slightly weaker conditions;
accepted for publication in the Journal of Theoretical Probabilit
First order valence transition in YbInCu_4 in the (B,T) - plane
The puzzling properties of the first order phase transition in YbInCu and
its alloys in the wide range of magnetic fields and temperatures are perfectly
described in terms of a simple entropy transition for free Yb ions. In
particular, it turns out that the transition line in the -plane is very
close to the elliptic shape, as it has been observed experimentally. Similar
calculations are done, and the experiments are proposed for the
phase transition in Ce in Megagauss fields. We speculate,
that in case of YbInCu the first order transition is a Mott transition
between a higher temperature phase in which localized moments are stabilized by
the entropy terms in the free energy, and a band-like non-magnetic ground state
of the -electrons.Comment: RevTeX, 5 pages, 2 figure
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