Epidemiologic aspects of neural tube defects in South East Iran

Objectives: To investigate the rate of neural tube defects (NTDs) and their relation to gender, maternal age, consanguineous marriage, season, and drug consumption in Birjand, Iran. Methods: This research was carried out on 16,785 live or stillborn newborns in Birjand, Iran from April 1997 to December 2001. Results: The rate of NTDs was 2.97 per 1000. This rate was 1.97 per 1000 in males, and 3.55 per 1000 in females. The rate of anencephaly was 1.37 per 1000, and spina bifida was 0.88 per 1000. We found that 32% of mothers with affected newborns had taken drugs during the first trimester of pregnancy, 90% of mothers did not consume folate before and during the first trimester, and 54% of parents had consanguineous marriage. Conclusion: We concluded that folate deficiency, usage of drugs during pregnancy, and consanguineous marriage may play a role of predisposition to NTD

Black Hole Horizon Fluffs: Near Horizon Soft Hairs as Microstates of Three Dimensional Black Holes

We provide the first explicit proposal for all microstates of generic black holes in three dimensions (of Banados-Teitelboim-Zanelli-type): black hole microstates, termed "horizon fluffs", are a particular class of near horizon soft hairs which have zero energy as measured by the horizon observer and cannot be distinguished by observers at finite distance from the horizon. These states are arranged in orbits of the two-dimensional conformal algebra associated with the asymptotic black hole geometry. We count these microstates using the Hardy-Ramanujan formula for the number of partitions of a given integer into non-negative integers, recovering the Bekenstein-Hawking entropy. We discuss possible extensions of our black hole microstate construction to astrophysical Kerr-type black holes.Comment: 6 pp, v2: reference added; equation defining black hole microstates made more precise, v3: extended discussion and relation to AdS3/CFT2, v5: discussion about the holographic picture and logarithmic correction to the entropy removed and referred to arXiv:1705.0625

Holographic Chern-Simons Theories

Chern-Simons theories in three dimensions are topological field theories that may have a holographic interpretation for suitable chosen gauge groups and boundary conditions on the fields. Conformal Chern-Simons gravity is a topological model of 3-dimensional gravity that exhibits Weyl invariance and allows various holographic descriptions, including Anti-de Sitter, Lobachevsky and flat space holography. The same model also allows to address some aspects that arise in higher spin gravity in a considerably simplified setup, since both types of models have gauge symmetries other than diffeomorphisms. In these lectures we summarize briefly recent results.Comment: 20 pp, invited lectures prepared for the 7th Aegean Summer School "Beyond Einstein's Theory of Gravity", 201

Semi-classical unitarity in 3-dimensional higher-spin gravity for non-principal embeddings

Higher-spin gravity in three dimensions is efficiently formulated as a Chern-Simons gauge-theory, typically with gauge algebra sl(N)+sl(N). The classical and quantum properties of the higher-spin theory depend crucially on the embedding into the full gauge algebra of the sl(2)+sl(2) factor associated with gravity. It has been argued previously that non-principal embeddings do not allow for a semi-classical limit (large values of the central charge) consistent with unitarity. In this work we show that it is possible to circumvent these conclusions. Based upon the Feigin-Semikhatov generalization of the Polyakov-Bershadsky algebra, we construct infinite families of unitary higher-spin gravity theories at certain rational values of the Chern-Simons level that allow arbitrarily large values of the central charge up to c = N/4 - 1/8 - O(1/N), thereby confirming a recent speculation by us 1209.2860.Comment: 20 pp in CQG style, 1 eps figure, v2: added labels in Fig. and 1 Re

Horizon fluff, semi-classical black hole microstates - Log-corrections to BTZ entropy and black hole/particle correspondence

According to the horizon fluff proposal microstates of a generic black hole belong to a certain subset of near horizon soft hairs that cannot be extended beyond the near horizon region. In [1,2] it was shown how the horizon fluff proposal works for AdS3 black holes. In this work we clarify further this picture by showing that BTZ black hole microstates are in general among the coherent states in the Hilbert space associated with conic spaces or their Virasoro descendants, provided we impose a (Bohr-type) quantization condition on the angular deficit. Thus BTZ black holes may be viewed as condensates (or solitonic states) of AdS3 particles. We provide canonical and microcanonical descriptions of the statistical mechanical system associated with BTZ black holes and their microstates, and relate them. As a further non-trivial check we show the horizon fluff proposal correctly reproduces the expected logarithmic corrections to the BTZ entropy.Comment: 47pp, v2: added references, minor correction in section 6.1, results unchanged, v3: 51pp, added figures, references and clarifications, to appear in JHE

Non-AdS holography in 3-dimensional higher spin gravity - General recipe and example

We present the general algorithm to establish the classical and quantum asymptotic symmetry algebra for non-AdS higher spin gravity and implement it for the specific example of spin-3 gravity in the non-principal embedding with Lobachevsky (H^2xR) boundary conditions. The asymptotic symmetry algebra for this example consists of a quantum W_3^2 (Polyakov-Bershadsky) and an affine u(1) algebra. We show that unitary representations of the quantum W_3^2 algebra exist only for two values of its central charge, the trivial c=0 "theory" and the simple c=1 theory.Comment: 23pp, v2: added Ref. [25], corrected typo in (5.4c

Novel Use of a Social-Media-Based Survey to Detect Regional Differences in Management of Monochorionic-Diamniotic Twins.

ObjectiveThis study aims to evaluate the utility of social media to distribute a patient survey on differences in management and outcomes of monochorionic-diamniotic (MCDA) pregnancies.Study designA cross-sectional survey was posted to an English-language MCDA twins patient-centered support group within the social media site, Facebook from April 2, 2018 to June 26, 2018. Subjects were recruited through a technique called "snowballing," whereby individuals shared the survey to assist with recruiting. Patient reported data were analyzed using Chi-square and Kruskal-Wallis's tests to explore characteristics associated with surveillance and outcomes as related to region and provider type.ResultsOver 3 months, the post "reached" 14,288 Facebook users, among which 5,653 (40%) clicked on the post. A total of 2,357 respondents with MCDA pregnancies completed the survey. Total 1,928 (82%) were from the United States (US) and 419 (18%) from other countries. Total 85% of patients had co-management with maternal-fetal medicine (MFM), more in the US compared with the rest of the world (87 vs. 74%, p < 0.01). MFM involvement led to increased adherence to biweekly ultrasounds (91 vs. 65%, p < 0.01), diagnosis of monochorionicity by 12 weeks (74 vs. 69%, p < 0.01) and better education about twin-twin transfusion syndrome (90 vs. 66%, p < 0.01). Pregnancies with MFM involvement had a higher take-home baby rate for both babies (92 vs. 89%, p < 0.01) or for at least one baby (98 vs. 93%, p < 0.01) compared with those without MFM involvement.ConclusionA survey distributed via social media can be effective in evaluating real-life management and outcomes of an uncommon obstetrical diagnosis. This survey elucidates wide international variation in adherence to guidelines, management, and outcomes

On massive gravitons in 2+1 dimensions

The Fierz-Pauli (FP) free field theory for massive spin 2 particles can be extended, in a spacetime of (1+2) dimensions (3D), to a generally covariant parity-preserving interacting field theory, in at least two ways. One is "new massive gravity" (NMG), with an action that involves curvature-squared terms. Another is 3D "bigravity", which involves non-linear couplings of the FP tensor field to 3D Einstein-Hilbert gravity. We review the proof of the linearized equivalence of both "massive 3D gravity" theories to FP theory, and we comment on their similarities and differences.Comment: 6 pages, to appear in the proceedings of the Spanish Relativity Meeting ERE2009, Bilbao; minor changes, reference adde

Microwire fibers for low-loss THz transmission

This paper was presented at Smart Structures, Devices, and Systems, which was a sub-conference contained within Smart Materials, Nano- and Micro-Smart Systems Symposium (10-13 December 2006 : Adelaide, South Australia). This paper was published in Smart Structures, Devices, and Systems III, edited by Said F. Al-Sarawi, Proc. of SPIE Vol. 6414, 64140I and is made available as an electronic reprint with permission of SPIE. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.In this paper, we will investigate microwire fibers for low-loss terahertz transmission. Microwires, air-clad wire waveguides with diameter smaller than the operating wavelength (a few μm), have an enhanced evanescent field and tight wave confinement resulting in a low loss waveguide structure for the terahertz (T-ray) frequency regime. Based on our experimental data for the bulk material absorption of four glasses (F2, SF6, SF57 and Bismuth) and a polymer (PMMA), we calculate the normalized field distribution, power fraction outside the wire and effective loss. It will be shown that regardless of material, the effective loss of all microwires converges to the same order < 0.01 cm -1.Shaghik Atakaramians, Shahraam Afshar Vahid, Bernd M. Fischer, Heike Ebendorff-Heidepriem, Tanya Monro and Derek Abbotthttp://spie.org/Documents/ConferencesExhibitions/au06-final.pd

Anisotropy of the Seebeck Coefficient in the Cuprate Superconductor YBa2_{2}Cu3_{3}Oy_{y}: Fermi-Surface Reconstruction by Bidirectional Charge Order

The Seebeck coefficient $S$ of the cuprate YBa$_{2}$Cu$_{3}$O$_{y}$ was measured in magnetic fields large enough to suppress superconductivity, at hole dopings $p = 0.11$ and $p = 0.12$, for heat currents along the $a$ and $b$ directions of the orthorhombic crystal structure. For both directions, $S/T$ decreases and becomes negative at low temperature, a signature that the Fermi surface undergoes a reconstruction due to broken translational symmetry. Above a clear threshold field, a strong new feature appears in $S_{\rm b}$, for conduction along the $b$ axis only. We attribute this feature to the onset of 3D-coherent unidirectional charge-density-wave modulations seen by x-ray diffraction, also along the $b$ axis only. Because these modulations have a sharp onset temperature well below the temperature where $S/T$ starts to drop towards negative values, we infer that they are not the cause of Fermi-surface reconstruction. Instead, the reconstruction must be caused by the quasi-2D bidirectional modulations that develop at significantly higher temperature.Comment: 7 pages, 5 figure