Coherent states for FLRW space-times in loop quantum gravity

We construct a class of coherent spin-network states that capture proprieties of curved space-times of the Friedmann-Lama\^itre-Robertson-Walker type on which they are peaked. The data coded by a coherent state are associated to a cellular decomposition of a spatial ($t=$const.) section with dual graph given by the complete five-vertex graph, though the construction can be easily generalized to other graphs. The labels of coherent states are complex SL(2, \mathbbm{C}) variables, one for each link of the graph and are computed through a smearing process starting from a continuum extrinsic and intrinsic geometry of the canonical surface. The construction covers both Euclidean and Lorentzian signatures; in the Euclidean case and in the limit of flat space we reproduce the simplicial 4-simplex semiclassical states used in Spin Foams.Comment: 10 pages, 1 figure, published versio

The Holst Spin Foam Model via Cubulations

Spin foam models are an attempt for a covariant, or path integral formulation of canonical loop quantum gravity. The construction of such models usually rely on the Plebanski formulation of general relativity as a constrained BF theory and is based on the discretization of the action on a simplicial triangulation, which may be viewed as an ultraviolet regulator. The triangulation dependence can be removed by means of group field theory techniques, which allows one to sum over all triangulations. The main tasks for these models are the correct quantum implementation of the Plebanski constraints, the existence of a semiclassical sector implementing additional "Regge-like" constraints arising from simplicial triangulations, and the definition of the physical inner product of loop quantum gravity via group field theory. Here we propose a new approach to tackle these issues stemming directly from the Holst action for general relativity, which is also a proper starting point for canonical loop quantum gravity. The discretization is performed by means of a "cubulation" of the manifold rather than a triangulation. We give a direct interpretation of the resulting spin foam model as a generating functional for the n-point functions on the physical Hilbert space at finite regulator. This paper focuses on ideas and tasks to be performed before the model can be taken seriously. However, our analysis reveals some interesting features of this model: first, the structure of its amplitudes differs from the standard spin foam models. Second, the tetrad n-point functions admit a "Wick-like" structure. Third, the restriction to simple representations does not automatically occur -- unless one makes use of the time gauge, just as in the classical theory.Comment: 25 pages, 1 figure; v3: published version. arXiv admin note: substantial text overlap with arXiv:0911.213

The DES (diethylstilbestrol) Years: Bridging the Past into the Future.

Between the years 1941–1971, it is estimated that between 5 million and 10 million pregnancies were exposed to diethylstilbestrol (DES).1 The adverse consequences of this exposure in utero had been reported as early as 1949.2 However, it was not until the development of a rare vaginal cancer known as clear-cell adenocarcinoma in 1971 that the implications with regard to teratogenicity of this steroid were identified.3 The use of anecdotal reports to develop preventive treatments cautions physicians regarding the consequences that may result when anecdotal reports are relied on to determine medical management rather than evidence-based research. This article will review the history and pathology of DES and alert the primary care physician to the misfortunes of our past and the implications they may have in the future. With the increased prevalence of alternative treatments and homeopathic remedies, the contemporary physician must be mindful of the importance of evidence-based medicine when prescribing therapeutics. Finally, this article will discuss the importance of evidence-based medicine and remind us to learn from our past experiences when we introduce new treatments in the future

Accuracy in Referrals to Gynecologic Oncologists Based on Clinical Presentation for Ovarian Mass

Ovarian cancer is one of the most lethal gynecological cancers in women due to late diagnosis. Despite technological advancements, experienced physicians have high sensitivities and specificities in subjective assessments when combining ultrasound findings and clinical history in analyzing adnexal masses. This study aims to demonstrate general obstetricians and gynecologists’ (OB/GYN) appropriateness in gynecologic oncologist referrals for malignant ovarian masses based on history and physical (H&P), imaging, and available tumor markers. Three board certified OB/GYNs were given 148 cases and determined whether or not they would refer them to a gynecologic oncologist. Results showed that OB/GYNs were 81–85% accurate in diagnosing patients with a benign or malignant disease. Among the malignant cases, reviewers had a high sensitivity ranging from 74–81% in appropriately referring a malignancy. In our study, OB/GYNs referred between 23–32% of ovarian masses to a gynecologic oncologist with only 9.5% of cases found to be malignant. Despite the high referral rates, generalists showed a high degree of sensitivity in accurately referring malignant diseases based solely on clinical experience and imaging studies, which could improve survival rates with early intervention by gynecologic oncologists