75,092 research outputs found
Comment on "Separability of quantum states and the violation of Bell-type inequalities"
The statement of E.R. Loubenets, Phys. Rev. A 69, 042102 (2004), that
separable states can violate classical probabilistic constraints is based on a
misleading definition of classicality, which is much narrower than Bell's
concept of local hidden variables. In a Bell type setting the notion of
classicality used by Loubenets corresponds to the assumption of perfect
correlations if the same observable is measured on both sides. While it is
obvious that most separable states do not satisfy this assumption, this does
not constitute "non-classical" behaviour in any usual sense of the word.Comment: 1 page, accepted by Phys. Rev.
Spectrophotometric Libraries, Revised Photonic Passbands and Zero-points for UBVRI, Hipparcos and Tycho Photometry
We have calculated improved photonic passbands for the UBV RI, Hipparcos and
Tycho Hp,BT,VT standard systems using the extensive spectrophotometric
libraries of NGSL and MILES. Using the Hp passband, we adjusted the absolute
flux levels of stars in the spectrophotometric libraries so their synthetic Hp
magnitudes matched the precise Hipparcos catalog value. Synthetic photometry
based on the renormalized fluxes were compared to the standard UBVRI and BT, VT
magnitudes and revised synthetic zero-points were determined. The Hipparcos and
Tycho photometry system zero-points were also compared to the V magnitude
zero-points of the SAAO UBVRI system, the homogenized UBV system and the
Walraven V B system. The confusion in the literature concerning broadband
magnitudes, fluxes, passbands and the choice of appropriate mean wavelengths is
detailed and discussed in an appendix.Comment: 44 pages, including 16 figures and a 12 page appendi
The Supreme Court, Due Process and State Income Taxation of Trusts
What are the constitutional limits on a state\u27s power to tax a trust with no connection to the state, other than the accident that a potential beneficiary lives there? The Supreme Court of the United States will take up this question this term in the context of North Carolina Department of Revenue v. Kimberley Rice Kaestner 1992 Family Trust. The case involves North Carolina\u27s income taxation of a trust with a contingent beneficiary, meaning someone who is eligible, but not certain, to receive a distribution or benefit from the trust, who resides in that state. Part I of this Article explains the background of Kaestner Trust and frames the constitutional questions that will be before the Court at oral arguments on April 16, 2019. Part II examines how and why due process applies in the state income taxation context, with a particular emphasis on how familiar concepts of general and specific jurisdiction apply uneasily to donative trusts. Part III articulates the reasons that the Court should hold that a state has no constitutional authority to impose a tax on trust income where the trust\u27s only connection with the forum state is the residence of a contingent beneficiary. Kaestner Trust is the most important due process case involving trusts that the Court has decided in over sixty years; it bears directly on the fundamental meaning of due process
Optimizing optical Bragg scattering for single-photon frequency conversion
We develop a systematic theory for optimising single-photon frequency
conversion using optical Bragg scattering. The efficiency and phase-matching
conditions for the desired Bragg scattering conversion as well as spurious
scattering and modulation instability are identified. We find that third-order
dispersion can suppress unwanted processes, while dispersion above the fourth
order limits the maximum conversion efficiency. We apply the optimisation
conditions to frequency conversion in highly nonlinear fiber, silicon nitride
waveguides and silicon nanowires. Efficient conversion is confirmed using full
numerical simulations. These design rules will assist the development of
efficient quantum frequency conversion between multicolour single photon
sources for integration in complex quantum networks.Comment: 9 pages, 14 figure
The rotation rates of massive stars: How slow are the slow ones?
Context: Rotation plays a key role in the life cycles of stars with masses
above 8 Msun. Hence, accurate knowledge of the rotation rates of such massive
stars is critical for understanding their properties and for constraining
models of their evolution. Aims: This paper investigates the reliability of
current methods used to derive projected rotation speeds v sin i from
line-broadening signatures in the photospheric spectra of massive stars,
focusing on stars that are not rapidly rotating. Methods: We use slowly
rotating magnetic O-stars with well-determined rotation periods to test the
Fourier transform (FT) and goodness-of-fit (GOF) methods typically used to
infer projected rotation rates of massive stars. Results: For our two magnetic
test stars with measured rotation periods longer than one year, i.e., with v
sin i < 1 km/s, we derive v sin i ~ 40-50 km/s from both the FT and GOF
methods. These severe overestimates are most likely caused by an insufficient
treatment of the competing broadening mechanisms referred to as microturbulence
and macroturbulence. Conclusions: These findings warn us not to rely
uncritically on results from current standard techniques to derive projected
rotation speeds of massive stars in the presence of significant additional line
broadening, at least when v sin i <~ 50 km/s. This may, for example, be crucial
for i) determining the statistical distribution of observed rotation rates of
massive stars, ii) interpreting the evolutionary status and spin-down histories
of rotationally braked B-supergiants, and iii) explaining the deficiency of
observed O-stars with spectroscopically inferred v sin i ~ 0 km/s. Further
investigations of potential shortcomings of the above techniques are presently
under way.Comment: 4 pages, 4 figures, accepted for publication in A&A Letter
Pilot-scale spiral wound membrane assessment for THM precursor rejection from upland waters
The outcomes of a pilot-scale study of the rejection of trihalomethanes (THMs) precursors by commercial ultrafiltration/nanofiltration (UF/NF) spiral-wound membrane elements are presented based on a single surface water source in Scotland. The study revealed the expected trend of increased flux and permeability with increasing pore size for the UF membranes; the NF membranes provided similar fluxes despite the lower nominal pore size. The dissolved organic carbon (DOC) passage decreased with decreasing molecular weight cut-off, with a less than one-third the passage recorded for the NF membranes than for the UF ones.
The yield (weight % total THMs per DOC) varied between 2.5% and 8% across all membranes tested, in reasonable agreement with the literature, with the aromatic polyamide membrane providing both the lowest yield and lowest DOC passage. The proportion of the hydrophobic (HPO) fraction removed was found to increase with decreasing membrane selectivity (increasing pore size), and THM generation correlated closely (R2 = 0.98) with the permeate HPO fractional concentration
First detection of a low-mass stellar halo around the young open cluster Eta Chamaeleontis
We have identified several lithium-rich low-mass (0.08<M<0.3 Msun) stars
within 5.5 deg of the young open cluster Eta Chamaeleontis, nearly four times
the radius of previous search efforts. Of these stars we propose 4 new probable
cluster members, and 3 possible members requiring further investigation. These
findings are consistent with a dynamical origin for the current configuration
of the cluster, without the need to invoke an abnormal Initial Mass Function
deficient in low-mass objects. Candidates were selected on the basis of DENIS
and 2MASS photometry, NOMAD astrometry and extensive follow-up spectroscopy.Comment: 5 Pages. 5 Figures and 1 Table. Accepted for publication in MNRAS
Letters. Higher resolution figures available at
http://www.mso.anu.edu.au/~murphysj/
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