752 research outputs found
Supertubes versus superconducting tubes
In this paper we show the relationship between cylindrical D2-branes and
cylindrical superconducting membranes described by a generic effective action
at the bosonic level. In the first case the extended objects considered, arose
as blown up type IIA superstrings to D2-branes, named supertubes. In the second
one, the cosmological objects arose from some sort of field theories. The
Dirac-Born-Infeld action describing supertubes is shown to be equivalent to the
generic effective action describing superconducting membranes via a special
transformation.Comment: Version with minor text changes with respect to the already publishe
Quenching of Star Formation
In the last decade we have seen an enormous increase in the size and quality
of spectroscopic galaxy surveys, both at low and high redshift. New statistical
techniques to analyse large portions of galaxy spectra are now finding favour
over traditional index based methods. Here we will review a new robust and
iterative Principal Component Analysis (PCA) algorithm, which solves several
common issues with classic PCA. Application to the 4000AA break region of
galaxies in the VIMOS VLT Deep Survey (VVDS) and Sloan Digital Sky Survey
(SDSS) gives new high signal-to-noise ratio spectral indices easily
interpretable in terms of recent star formation history. In particular, we
identify a sample of post-starburst galaxies at z~0.7 and z~0.07. We quantify
for the first time the importance of post-starburst galaxies, consistent with
being descendants of gas-rich major mergers, for building the red sequence.
Finally, we present a comparison with new low and high redshift "mock
spectroscopic surveys" derived from a Millennium Run semi-analytic model.Comment: 7 pages, 3 figures. Conference proceedings in "Classification and
Discovery in Large Astronomical Surveys", 2008, C.A.L. Bailer-Jones (ed.
Vergrijzing, aanvullende pensioenen en de Nederlandse economie
De vergrijzingsproblematiek betreft alle Westerse landen. De gecombineerde effecten
van een lager geboortecijfer, een lager sterftecijfer en de naoorlogse geboortegolf
leiden ertoe dat de bevolkingsopbouw aan het veranderen is. Volgens het
CBS zal het bevolkingsaandeel van ouderen (met een leeftijd van 65 jaar of hoger)
de komende jaren stijgen van 13% naar ruim 22%. Deze verandering zal zijn
weerslag hebben in de hele economie, en bijzonder gevoeld worden in de pensioensector
Theory of a magnetic microscope with nanometer resolution
We propose a theory for a type of apertureless scanning near field microscopy
that is intended to allow the measurement of magnetism on a nanometer length
scale. A scanning probe, for example a scanning tunneling microscope (STM) tip,
is used to scan a magnetic substrate while a laser is focused on it. The
electric field between the tip and substrate is enhanced in such a way that the
circular polarization due to the Kerr effect, which is normally of order 0.1%
is increased by up to two orders of magnitude for the case of a Ag or W tip and
an Fe sample. Apart from this there is a large background of circular
polarization which is non-magnetic in origin. This circular polarization is
produced by light scattered from the STM tip and substrate. A detailed retarded
calculation for this light-in-light-out experiment is presented.Comment: 17 pages, 8 figure
A random matrix decimation procedure relating to
Classical random matrix ensembles with orthogonal symmetry have the property
that the joint distribution of every second eigenvalue is equal to that of a
classical random matrix ensemble with symplectic symmetry. These results are
shown to be the case of a family of inter-relations between eigenvalue
probability density functions for generalizations of the classical random
matrix ensembles referred to as -ensembles. The inter-relations give
that the joint distribution of every -st eigenvalue in certain
-ensembles with is equal to that of another
-ensemble with . The proof requires generalizing a
conditional probability density function due to Dixon and Anderson.Comment: 19 pages, 1 figur
Friends or Foes? Emerging Impacts of Biological Toxins
Toxins are substances produced from biological sources (e.g., animal, plants, microorganisms) that have deleterious effects on a living organism. Despite the obvious health concerns of being exposed to toxins, they are having substantial positive impacts in a number of industrial sectors. Several toxin-derived products are approved for clinical, veterinary, or agrochemical uses. This review sets out the case for toxins as ‘friends’ that are providing the basis of novel medicines, insecticides, and even nucleic acid sequencing technologies. We also discuss emerging toxins (‘foes’) that are becoming increasingly prevalent in a range of contexts through climate change and the globalisation of food supply chains and that ultimately pose a risk to health
22. juli kommisjonen. Organisering, styring og ansvar [The 22. July Commission. Organization, steering and accountability].
INNLEIING
22. juli 2011 vart Norge ramma av to sjokkerande terroristangrep. Ei bilbombe øydela fleire sentrale regjeringsbygningar i Oslo og 8 personar vart drepne i angrepet. Nokre få timar seinare vart 69 politisk aktive ungdomar frå Arbeiderpartiet si ungdomsorganisasjon massakrert på ein leir på Utøya – like nordvest for Oslo. Dei fleste av dei 69 offera var mellom 15 og 18 år. Terroristen vart arrestert på Utøya same kvelden og vedgjekk straks ugjerningane. Rettsaka vist at han var ein ‘einsam ulv’ som opererte åleine utan å vera tilknytt nokon organisasjon. 24. august 2012 vart han dømt til 21 års forvaring
Critical Percolation in High Dimensions
We present Monte Carlo estimates for site and bond percolation thresholds in
simple hypercubic lattices with 4 to 13 dimensions. For d<6 they are
preliminary, for d >= 6 they are between 20 to 10^4 times more precise than the
best previous estimates. This was achieved by three ingredients: (i) simple and
fast hashing which allowed us to simulate clusters of millions of sites on
computers with less than 500 MB memory; (ii) a histogram method which allowed
us to obtain information for several p values from a single simulation; and
(iii) a new variance reduction technique which is especially efficient at high
dimensions where it reduces error bars by a factor up to approximately 30 and
more. Based on these data we propose a new scaling law for finite cluster size
corrections.Comment: 5 pages including figures, RevTe
Portable blood gas and electrolyte analyzer evaluated in a multiinstitutional study
A recently introduced blood gas/electrolyte analyzer (SenDx 100((R)),
renamed ABL70) intended for point-of-care, near-patient, or stat
laboratory use was evaluated simultaneously in four different institutions
and compared with three different laboratory bench analyzers with respect
to imprecision, inaccuracy (assessed by tonometry), and patient-sample
analyses. The analyzer is equipped with a sensor cassette and a reagent
cartridge for 50, 100, or 200 analyses and 100 or more traditional
quality-control measurements. One analysis requires 170 microL of whole
blood and takes <90 s. Statistically, the instrument performed somewhat
better (lower CVs) for PO2 and potassium and somewhat worse for pH, PCO2,
and ionized calcium than the respective comparison analyzers. However, the
overall performance (in terms of CV and accuracy) was satisfactory in
terms of clinical (e.g., CLIA '88) goals in all institutions. The mean
difference and the CV of that difference in some 400 patient-sample
comparisons were as follows: 0.010 (+/- 0.002%) for pH, -0.65 mmHg (+/-
4%) for PCO2, -0.49 mmHg (+/- 6%) for Po2, 0.44 mmol/L (+/- 1.2%) for
sodium, -0.013 mmol/L (+/- 2.9%) for potassium, -0.016 mmol/L (+/- 2.6%)
for ionized calcium, and -0.016 L/L (+/- 7. 1%) for the hematocrit. Its
acceptable analytical performance and ease of operation make the SenDx 100
suitable for the analysis of blood gases and electrolytes
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