We revisit the recently proposed mechanism of Geometric Inflation. On general grounds, we show that obtaining the right amount of inflation demands an exceedingly large initial energy density. We introduce a scalar field and study the combined action of both mechanisms. Besides fixing the aforementioned issue, a cascading process occurs whose last step seems undistinguishable from ordinary large field inflation. Strikingly, the scalar field remains approximately constant while Geometric Inflation rules the dynamics. This ultimately leads to the possibility of reducing the initial value of the scalar field and its excursion. We discuss the main features of this hybrid scenario.
Within General Relativity, a minimally coupled scalar field governed by a quadratic potential is able to produce an accelerated expansion of the universe provided its value and excursion are larger than the Planck scale. This is an archetypical example of the so called large field inflation models. We show that by including higher curvature corrections to the gravitational action in the form of the Geometric Inflation models, it is possible to obtain accelerated expansion with a free scalar field whose values are well below the Planck scale, thereby turning a traditional large field model into a small field one. We provide the conditions the theory has to satisfy in order for this mechanism to operate, and we present two explicit models illustrating it. Finally, we present some open questions raised by this scenario in which inflation takes place completely in a higher curvature dominated regime, such as those concerning the study of perturbations.
We implement a universal method for renormalizing AdS gravity actions applicable to arbitrary higher curvature theories in up to five dimensions. The renormalization procedure considers the extrinsic counterterm for Einstein-AdS gravity given by the Kounterterms scheme, but with a theory-dependent coupling constant that is fixed by the requirement of renormalization for the vacuum solution. This method is shown to work for a generic higher curvature gravity with arbitrary couplings except for a zero measure subset, which includes well-known examples where the asymptotic behavior is modified and the AdS vacua are degenerate, such as Chern-Simons gravity in 5D, Conformal Gravity in 4D and New Massive Gravity in 3D. In order to show the universality of the scheme, we perform a decomposition of the equations of motion into their normal and tangential components with respect to the Poincare coordinate and study the Fefferman-Graham expansion of the metric. We verify the cancellation of divergences of the on-shell action and the well-posedness of the variational principle.
Objective
To identify the preoperative clinical conditions associated with the need to perform a blood transfusion among patients undergoing hysterectomy.
Methods
In a retrospective, comparative, case–control trial at the University Hospital, Nuevo León, Mexico, the records of patients who underwent elective hysterectomy between 2007 and 2009 were reviewed. Patients were grouped depending on whether or not they required blood transfusion. Clinical features were compared and statistical analysis was performed via the χ2 test.
Results
Among 794 patients who underwent hysterectomy, 89 (11.2%) required transfusion. The factors significantly associated with transfusion were history of abnormal uterine bleeding (67.0% versus 52.1%), preoperative hemoglobin level (10.1 g/dL versus 12.3 g/dL), magnitude of intra‐operative bleeding (410 mL versus 298 mL), and operative time (172 min versus 144 min); P < 0.001. A significant number of patients who underwent transfusion had increased preoperative prothrombin levels; P = 0.04.
Conclusion
Hemoglobin level before surgery and a history of abnormal uterine bleeding can be identified preoperatively and might warn about the possibility of a need for transfusion among patients undergoing hysterectomy. For young patients, alterations in clotting mechanisms should be ruled out.
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