18,040 research outputs found

    Predicting Lotto Numbers

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    We investigate the "law of small numbers" using a unique panel data set on lotto gambling. Because we can track individual players over time, we can measure how they react to outcomes of recent lotto drawings. We can therefore test whether they behave as if they believe they can predict lotto numbers based on recent drawings. While most players pick the same set of number week after week without regards of numbers drawn or anything else, we find that those who do change, act on average in the way predicted by the law of small numbers as formalized in recent behavioral theory. In particular, on average they move away from numbers that are on streak, i.e. have been drawn several weeks in a row, consistent with the "hot hand fallacy".gambler's fallacy;hot hand fallacy;representativeness;law of small numbers

    Observations of nitrogen isotope fractionation in deeply embedded protostars

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    (Abridged) The terrestrial planets, comets, and meteorites are significantly enriched in 15N compared to the Sun and Jupiter. While the solar and jovian nitrogen isotope ratio is believed to represent the composition of the protosolar nebula, a still unidentified process has caused 15N-enrichment in the solids. Several mechanisms have been proposed to explain the variations, including chemical fractionation. However, observational results that constrain the fractionation models are scarce. While there is evidence of 15N-enrichment in prestellar cores, it is unclear how the signature evolves into the protostellar phases. Our aim is to measure the 14N/15N ratio around three nearby, embedded low-to-intermediate-mass protostars. Isotopologues of HCN and HNC were used to probe the 14N/15N ratio. A selection of H13CN, HC15N, HN13C, and H15NC transitions was observed with the APEX telescope. The 14N/15N ratios were derived from the integrated intensities assuming a standard 12C/13C ratio. The assumption of optically thin emission was verified using radiative transfer modeling and hyperfine structure fitting. Two sources, IRAS 16293A and R CrA IRS7B, show 15N-enrichment by a factor of around 1.5-2.5 in both HCN and HNC with respect to the solar composition. Solar composition cannot be excluded for the third source, OMC-3 MMS6. Furthermore, there are indications of a trend toward increasing 14N/15N ratios with increasing outer envelope temperature. The enhanced 15N abundances in HCN and HNC found in two Class~0 sources (14N/15N of 160-290) and the tentative trend toward a temperature-dependent 14N/15N ratio are consistent with the chemical fractionation scenario, but 14N/15N ratios from additional tracers are indispensable for testing the models. Spatially resolved observations are needed to distinguish between chemical fractionation and isotope-selective photochemistry.Comment: Accepted for publication in Astronomy and Astrophysics. 16 pages, 13 figure

    The Sloan-Lens ACS Survey II: stellar populations and internal structure of early-type lens galaxies

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    We derive Fundamental Plane parameters of 15 early-type lens galaxies identified by the Sloan Lens ACS (SLACS) Survey. The size of the sample allows us to investigate for the first time the distribution of lens galaxies in the FP space. After correcting for evolution, we find that lens galaxies occupy a subset of the local FP. The edge-on projection (approximately M vs M/L) is indistinguishable from that of normal early-type galaxies. However -- within the fundamental plane -- the lens galaxies appear to concentrate at the edge of the region populated by normal early-type galaxies. We show that this is a result of our selection procedure (approximately velocity dispersion sigma>240km/s). We conclude that SLACS lenses are a fair sample of high velocity dispersion early-type galaxies. By comparing the central stellar velocity dispersion that of the best fit lens model, we find == =1.01+-0.02 with 0.065 rms scatter. We conclude that within the Einstein radii the SLACS lenses are very well approximated by isothermal ellipsoids, requiring a fine tuning of the stellar and dark matter distribution (bulge-halo ``conspiracy''). Interpreting the offset from the local FP in terms of evolution of the stellar mass-to-light ratio, we find for the SLACS lenses d log M/L_B/dz=-0.69+-0.08 (rms 0.11) consistent with the rate found for field early-type galaxies and with a scenario where most of the stars were formed at high redshift (>2) with secondary episodes of star formation providing less than ~10% of the stellar mass below z=1. We discuss star formation history and structural homogeneity in the context of formation mechanisms such as collisionless (``dry'') mergers. [Abridged]Comment: 2006, ApJ, 604, 622; 13 pages, 7 figures, 2 tables. Replaced Table 2, since the previous version was incorrectly sorted. Updated references. No changes in plots or content. More info available at SLACS website www.slacs.or

    Commuting self-adjoint extensions of symmetric operators defined from the partial derivatives

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    We consider the problem of finding commuting self-adjoint extensions of the partial derivatives {(1/i)(\partial/\partial x_j):j=1,...,d} with domain C_c^\infty(\Omega) where the self-adjointness is defined relative to L^2(\Omega), and \Omega is a given open subset of R^d. The measure on \Omega is Lebesgue measure on R^d restricted to \Omega. The problem originates with I.E. Segal and B. Fuglede, and is difficult in general. In this paper, we provide a representation-theoretic answer in the special case when \Omega=I\times\Omega_2 and I is an open interval. We then apply the results to the case when \Omega is a d-cube, I^d, and we describe possible subsets \Lambda of R^d such that {e^(i2\pi\lambda \dot x) restricted to I^d:\lambda\in\Lambda} is an orthonormal basis in L^2(I^d).Comment: LaTeX2e amsart class, 18 pages, 2 figures; PACS numbers 02.20.Km, 02.30.Nw, 02.30.Tb, 02.60.-x, 03.65.-w, 03.65.Bz, 03.65.Db, 61.12.Bt, 61.44.B

    Inhibition of MDR1 does not sensitize primitive chronic myeloid leukemia CD34<sup>+</sup> cells to imatinib

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    &lt;p&gt;&lt;b&gt;Objective:&lt;/b&gt; To investigate the interaction of imatinib mesylate (IM) with the clinically relevant adenosine triphosphate-binding cassette efflux transporter MDR1 (ABCB1) in cells from patients with chronic myeloid leukemia (CML) and to explore whether inhibition of this transporter would improve IM's efficacy in the elimination of CML CD34&lt;sup&gt;+&lt;/sup&gt; cells by increasing cell-associated drug accumulation.&lt;/p&gt; &lt;p&gt;&lt;b&gt;Materials and Methods:&lt;/b&gt; Cells from newly diagnosed chronic-phase CML patients were harvested by leukapheresis and enriched to &gt;95% CD34&lt;sup&gt;+&lt;/sup&gt;. Expression of the transporter gene MDR1 was performed by quantitative reverse transcription polymerase chain reaction. Interaction of IM with MDR1 was analyzed by substrate (rhodamine 123) displacement assay. Cell-associated levels of IM in CML CD34&lt;sup&gt;+&lt;/sup&gt; cells were measured by high-pressure liquid chromatography. Intracellular phospho-CrkL levels, apoptosis in total CML CD34&lt;sup&gt;+&lt;/sup&gt; cells and high-resolution tracking of cell division were assayed by flow cytometry.&lt;/p&gt; &lt;p&gt;&lt;b&gt;Results:&lt;/b&gt; Measurements of cell-associated IM uptake showed significantly lower drug levels in CD34&lt;sup&gt;+&lt;/sup&gt; cells, particularly the CD38&lt;sup&gt;-&lt;/sup&gt; subpopulation, as compared to IM-sensitive K562 cells. MDR1 was expressed at low level and dye efflux studies demonstrated very little MDR1 activity in CML CD34&lt;sup&gt;+&lt;/sup&gt; cells. Furthermore, combination treatment of primitive CML cells with IM and the MDR1 inhibitor PSC833 did not result in elevated cell-associated IM levels. Although we observed slightly enhanced cytostasis with IM when combined with PSC833, this was independent of BCR-ABL inhibition because no associated decrease in phospho-CrkL was observed.&lt;/p&gt; &lt;p&gt;&lt;b&gt;Conclusions:&lt;/b&gt; Our findings demonstrate that inhibition of MDR1 neither enhances the effect of IM against BCR-ABL activity, nor significantly potentiates IM's efficiency in eliminating primitive CML cells.&lt;/p&gt

    On the theory of SODAR measurement techniques (final reporting on WP1, EU WISE project NNE5-2001-297)

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    The need for alternative means to measure the wind speed for wind energy purposes has increased with the increase of the size of wind turbines. The cost and the technical difficulties for performing wind speed measurements has also increased with the size of the wind turbines, since it is demanded that the wind speed has to be measured at the rotor center of the turbine and the size of both the rotor and the hub height have grown following the increase in the size of the wind turbines. The SODAR (SOund Detection And Ranging) is an alternative to the use of cup anemometers and offers the possibility of measuring both the wind speed distribution with height and the wind direction. At the same time the SODAR presents a number of serious drawbacks such as the low number of measurements per time period, the dependence of the ability to measure on the atmospheric conditions and the difficulty of measuring at higher wind speeds due to either background noise or the neutral condition of the atmosphere. Within the WISE project (EU project number NNE5-2001-297), a number of work packages have been defined in order to deal with the SODAR. The present report is the result of the work package 1. Within this package the objective has been to present and achieve the following: - An accurate theoretic model that describes all the relevant aspects of the interaction of the sound beam with the atmosphere in the level of detail needed for wind energy applications. - Understanding of dependence of SODAR performance on hard- and software configuration. - Quantification of principal difference between SODAR wind measurement and wind speed measurements with cup anemometers with regard to power performance measurements. The work associated to the above is described in the work program as follows: a) Draw up an accurate model of the theoretic background of the SODAR. The necessary depth is reached when the influences of various variables in the model on the accuracy of the measurement have been assessed. b) Describe the general algorithm SODAR uses for sending the beam and measuring the reflections. Describe the influence of various settings on the working of the algorithm. c) Using the data set from work package two analyse the differences between point measurements and profile measurements. All the above issues are addressed in the following repor
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