DHCR7 mutations linked to higher vitamin D status allowed early human migration to Northern latitudes

PMCID: PMC3708787This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited

Generating Polarization-Entangled Photon Pairs with Arbitrary Joint Spectrum

We present a scheme for generating polarization-entangled photons pairs with arbitrary joint spectrum. Specifically, we describe a technique for spontaneous parametric down-conversion in which both the center frequencies and the bandwidths of the down-converted photons may be controlled by appropriate manipulation of the pump pulse. The spectral control offered by this technique permits one to choose the operating wavelengths for each photon of a pair based on optimizations of other system parameters (loss in optical fiber, photon counter performance, etc.). The combination of spectral control, polarization control, and lack of group-velocity matching conditions makes this technique particularly well-suited for a distributed quantum information processing architecture in which integrated optical circuits are connected by spans of optical fiber.Comment: 6 pages, 3 figure

Performance of Photon-Pair Quantum Key Distribution Systems

We analyze the quantitative improvement in performance provided by a novel quantum key distribution (QKD) system that employs a correlated photon source (CPS) and a photon-number resolving detector (PNR). Our calculations suggest that given current technology, the CPR implementation offers an improvement of several orders of magnitude in secure bit rate over previously described implementations

Symmetric Autocompensating Quantum Key Distribution

We present quantum key distribution schemes which are autocompensating (require no alignment) and symmetric (Alice and Bob receive photons from a central source) for both polarization and time-bin qubits. The primary benefit of the symmetric configuration is that both Alice and Bob may have passive setups (neither Alice nor Bob is required to make active changes for each run of the protocol). We show that both the polarization and the time-bin schemes may be implemented with existing technology. The new schemes are related to previously described schemes by the concept of advanced waves.Comment: 4 pages, 2 figur

Parallel-Plate Electrochemical Reactor Model: A Method for Determining the Time-Dependent Behavior and the Effects of Axial Diffusion and Axial Migration

A method is presented for determining the effects of time dependence, axial diffusion, and axial migration in aparallel-plate electrochemical reactor (PPER). The method consists of formulating the governing equations and applying a numerical integration technique to solve a set of time-dependent, nonlinear, coupled, multidimensional equations. This formulation reveals that the steady-state performance of the PPER depends on the cell potential and three dimensionless groups. Predictions of the concentration, potential, and local current distributions in a PPER are presented for the electrowinning of copper from an aqueous, hydrochloric acid solution. These predictions show that axial diffusion and axial migration are significant when the aspect ratio (i.e., the ratio of electrode separation to electrode length) is greater than 0.5

Raman spectroscopy of the low dimensional antiferromagnet with large Neel temperature SrRu2O6

We report results of the Raman measurements for SrRu$_2$O$_6$ having extraordinary high N$\acute{\textrm{e}}$el temperature for a layered material. No additional phonon modes were detected at the temperature of magnetic transition thus excluding lowering of the symmetry in the magnetically ordered phase. An unusual increase in softening and damping of some phonons as the temperature approaches $T_N$ indicate the appearance of a continuum of interacting electronic excitations at $T\geq300K$. We also observe an intensive Raman response at 2050 cm$^{-1}$. Analysis of the polarization dependence and comparison with available theoretical data shows that this peak likely originates from the transitions between molecular orbitals previously proposed to explain the magnetic properties of SrRu$_2$O$_6$

Berenstein-Zelevinsky triangles, elementary couplings and fusion rules

We present a general scheme for describing su(N)_k fusion rules in terms of elementary couplings, using Berenstein-Zelevinsky triangles. A fusion coupling is characterized by its corresponding tensor product coupling (i.e. its Berenstein-Zelevinsky triangle) and the threshold level at which it first appears. We show that a closed expression for this threshold level is encoded in the Berenstein-Zelevinsky triangle and an explicit method to calculate it is presented. In this way a complete solution of su(4)_k fusion rules is obtained.Comment: 14 page

Lie group weight multiplicities from conformal field theory

Dominant weight multiplicities of simple Lie groups are expressed in terms of the modular matrices of Wess-Zumino-Witten conformal field theories, and related objects. Symmetries of the modular matrices give rise to new relations among multiplicities. At least for some Lie groups, these new relations are strong enough to completely fix all multiplicities.Comment: 12 pages, Plain TeX, no figure

Can feedback approaches reduce unwarranted clinical variation? A systematic rapid evidence synthesis.

BACKGROUND:Assessment of clinical variation has attracted increasing interest in health systems internationally due to growing awareness about better value and appropriate health care as a mechanism for enhancing efficient, effective and timely care. Feedback using administrative databases to provide benchmarking data has been utilised in several countries to explore clinical care variation and to enhance guideline adherent care. Whilst methods for detecting variation are well-established, methods for determining variation that is unwarranted and addressing this are strongly debated. This study aimed to synthesize published evidence of the use of feedback approaches to address unwarranted clinical variation (UCV). METHODS:A rapid review and narrative evidence synthesis was undertaken as a policy-focused review to understand how feedback approaches have been applied to address UCV specifically. Key words, synonyms and subject headings were used to search the major electronic databases Medline and PubMed between 2000 and 2018. Titles and abstracts of publications were screened by two reviewers and independently checked by a third reviewer. Full text articles were screened against the eligibility criteria. Key findings were extracted and integrated in a narrative synthesis. RESULTS:Feedback approaches that occurred over a duration of 1 month to 9 years to address clinical variation emerged from 27 publications with quantitative (20), theoretical/conceptual/descriptive work (4) and mixed or multi-method studies (3). Approaches ranged from presenting evidence to individuals, teams and organisations, to providing facilitated tailored feedback supported by a process of ongoing dialogue to enable change. Feedback approaches identified primarily focused on changing clinician decision-making and behaviour. Providing feedback to clinicians was identified, in a range of a settings, as associated with changes in variation such as reducing overuse of tests and treatments, reducing variations in optimal patient clinical outcomes and increasing guideline or protocol adherence. CONCLUSIONS:The review findings suggest value in the use of feedback approaches to respond to clinical variation and understand when action is warranted. Evaluation of the effectiveness of particular feedback approaches is now required to determine if there is an optimal approach to create change where needed