Improving Mechanical Ventilator Clinical Decision Support Systems with A Machine Learning Classifier for Determining Ventilator Mode

Clinical decision support systems (CDSS) will play an in-creasing role in improving the quality of medical care for critically ill patients. However, due to limitations in current informatics infrastructure, CDSS do not always have com-plete information on state of supporting physiologic monitor-ing devices, which can limit the input data available to CDSS. This is especially true in the use case of mechanical ventilation (MV), where current CDSS have no knowledge of critical ventilation settings, such as ventilation mode. To enable MV CDSS to make accurate recommendations related to ventilator mode, we developed a highly performant ma-chine learning model that is able to perform per-breath clas-sification of 5 of the most widely used ventilation modes in the USA with an average F1-score of 97.52%. We also show how our approach makes methodologic improvements over previous work and that it is highly robust to missing data caused by software/sensor error

Effects of Secular Interactions in Extrasolar Planetary Systems

This paper studies the effects of dynamical interactions among the planets in observed extrasolar planetary systems, including hypothetical additional bodies, with a focus on secular perturbations. These interactions cause the eccentricities of the planets to explore a distribution of values over time scales that are long compared to observational time baselines, but short compared to the age of the systems. The same formalism determines the eccentricity forcing of hypothetical test bodies (terrestrial planets) in these systems and we find which systems allow for potentially habitable planets. Such planets would be driven to nonzero orbital eccentricity and we derive the distribution of stellar flux experienced by the planets over the course of their orbits. The general relativistic corrections to secular interaction theory are included in the analysis and such effects are important in systems with close planets ($\sim$4 day orbits). Some extrasolar planetary systems (e.g., Upsilon Andromedae) can be used as a test of general relativity, whereas in other systems, general relativity can be used to constrain the system parameters (e.g., \sin i \gta 0.93 for HD160691). For the case of hot Jupiters, we discuss how the absence of observed eccentricity implies the absence of companion planets.Comment: 32 pages, 11 figures, accepted for publication in Ap

Long Term Evolution of Close Planets Including the Effects of Secular Interactions

This paper studies the long term evolution of planetary systems containing short-period planets, including the effects of tidal circularization, secular excitation of eccentricity by companion planets, and stellar damping. For planetary systems subject to all of these effects, analytic solutions (or approximations) are presented for the time evolution of the semi-major axes and eccentricities. Secular interactions enhance the inward migration and accretion of hot Jupiters, while general relativity tends to act in opposition by reducing the effectiveness of the secular perturbations. The analytic solutions presented herein allow us to understand these effects over a wide range of parameter space and to isolate the effects of general relativity in these planetary systems.Comment: 14 pages, 2 figures, accepted to Ap

Assessment of an Innovative Medication Adherence Training Exercise in an Interprofessional Training Program

OBJECTIVE To assess the effect of an innovative training exercise on post-graduate healthcare trainees’ knowledge and perspectives of medication adherence and skills gained within an interprofessional training program. METHODS Postgraduate trainees (medicine, pharmacy, advanced practice nursing, and mental health) at the Michael E. DeBakey VA Medical Center’s Center of Excellence in Primary Care Education interprofessional training program participated in a medication adherence exercise and training session. The session included a formal PowerPoint presentation, an innovative medication adherence simulation exercise, clinical scenarios, and a journal club. Verbal feedback during the debriefing session occurred after the medication adherence simulation exercise and throughout the session. RESULTS Six trainees participated in the exercise and training session (2 medical residents, 2 nurse practitioner residents, 1 pharmacy resident, and 1 clinical psychology fellow). Trainees reported developing a greater understanding for barriers patients face with medication adherence, empathy, and strategies to manage patients’ medication adherence. CONCLUSIONS The medication adherence exercise and training session provided an opportunity for healthcare professionals from different professions to discuss medication adherence and share their educational training and previous clinical experiences within an interprofessional training program

Superluminality in DGP

We reconsider the issue of superluminal propagation in the DGP model of infrared modified gravity. Superluminality was argued to exist in certain otherwise physical backgrounds by using a particular, physically relevant scaling limit of the theory. In this paper, we exhibit explicit five-dimensional solutions of the full theory that are stable against small fluctuations and that indeed support superluminal excitations. The scaling limit is neither needed nor invoked in deriving the solutions or in the analysis of its small fluctuations. To be certain that the superluminality found here is physical, we analyze the retarded Green's function of the scalar excitations, finding that it is causal and stable, but has support on a widened light-cone. We propose to use absence of superluminal propagation as a method to constrain the parameters of the DGP model. As a first application of the method, we find that whenever the 4D energy density is a pure cosmological constant and a hierarchy of scales exists between the 4D and 5D Planck masses, superluminal propagation unavoidably occurs.Comment: 23 pages. Minor corrections. Version to appear in JHE

Risk Stratification for Bleeding Complications in Patients With Venous Thromboembolism: Application of the HAS-BLED Bleeding Score During the First 6 Months of Anticoagulant Treatment

Background—The Hypertension, Abnormal renal/liver function, Stroke, Bleeding, Labile International Normalized Ratio (INR), Elderly, Drugs or alcohol use (HAS-BLED) score has strong predictive validity for major bleeding complications, but limited validation has been conducted in venous thromboembolism (VTE). This study evaluates the HAS-BLED score in a large cohort of VTE patients. Methods and Results—A retrospective cohort of adults ≥ 18 years with primary diagnosis of VTE between January 1, 2010 and November 31, 2013 were identified in an insurance claims database. Patients were tracked until death, any bleed event, or end of study period. HAS-BLED score and components were evaluated via proportional hazard models. Cumulative incidence functions were reported at 30, 60, 90, and 180 days. N=132 280 patients with a VTE were identified, with 73.8% having HAS-BLED scores of 0 to 2, 3.6% score ≥ 4, and 4789 bleeding events (3.6% all patients). A 1-point HAS-BLED score increase was associated with 20% to 30% bleeding rate increase overall, but in a cancer cohort only the increase from 3- to 4-points was significant for all bleeds (csHR=1.41, 95% CI: 1.17-1.69; sdHR=1.40, 95% CI: 1.17-1.69) and major bleeds (csHR=1.66, 95% CI: 1.26-2.20; sdHR=1.66, 95% CI: 1.25-2.19). Adding cancer to the model as an independent covariate provided the strongest association among all covariates, with csHR=2.25 (95% CI: 1.98-2.56) and sdHR=2.11 (95% CI: 1.85-2.41) in the model for major bleeds. Conclusions—The HAS-BLED score has good predictive validity for bleeding risks in patients with VTE. The addition of cancer as an independent bleeding risk factor merits consideration, possibly as part of the B criterion ( bleeding tendency or predisposition )

On the CSFT approach to localized closed string tachyons

We compute the potential for localized closed string tachyons in bosonic string theory on the orbifold C/Z_4 using level-truncated closed string field theory. The critical points of the potential exhibit features which agree with their conjectured identification as lower-order orbifolds. However this case also raises some questions regarding the quantitative predictions associated with these conjectures.Comment: 20 pages, 3 figures, v2: The relation between the flat space and orbifold gravitational constants has been corrected. This resolves the puzzle of multiple predictions, but worsens the agreement between the depth of the potential and the change in the deficit angl

Localized Tachyons and the Quantum McKay Correspondence

The condensation of closed string tachyons localized at the fixed point of a C^d/\Gamma orbifold can be studied in the framework of renormalization group flow in a gauged linear sigma model. The evolution of the Higgs branch along the flow describes a resolution of singularities via the process of tachyon condensation. The study of the fate of D-branes in this process has lead to a notion of a ``quantum McKay correspondence.'' This is a hypothetical correspondence between fractional branes in an orbifold singularity in the ultraviolet with the Coulomb and Higgs branch branes in the infrared. In this paper we present some nontrivial evidence for this correspondence in the case C^2/Z_n by relating the intersection form of fractional branes to that of ``Higgs branch branes,'' the latter being branes which wrap nontrivial cycles in the resolved space.Comment: 25 pages; harvma

Reproducing Kernels of Generalized Sobolev Spaces via a Green Function Approach with Distributional Operators

In this paper we introduce a generalized Sobolev space by defining a semi-inner product formulated in terms of a vector distributional operator $\mathbf{P}$ consisting of finitely or countably many distributional operators $P_n$, which are defined on the dual space of the Schwartz space. The types of operators we consider include not only differential operators, but also more general distributional operators such as pseudo-differential operators. We deduce that a certain appropriate full-space Green function $G$ with respect to $L:=\mathbf{P}^{\ast T}\mathbf{P}$ now becomes a conditionally positive definite function. In order to support this claim we ensure that the distributional adjoint operator $\mathbf{P}^{\ast}$ of $\mathbf{P}$ is well-defined in the distributional sense. Under sufficient conditions, the native space (reproducing-kernel Hilbert space) associated with the Green function $G$ can be isometrically embedded into or even be isometrically equivalent to a generalized Sobolev space. As an application, we take linear combinations of translates of the Green function with possibly added polynomial terms and construct a multivariate minimum-norm interpolant $s_{f,X}$ to data values sampled from an unknown generalized Sobolev function $f$ at data sites located in some set $X \subset \mathbb{R}^d$. We provide several examples, such as Mat\'ern kernels or Gaussian kernels, that illustrate how many reproducing-kernel Hilbert spaces of well-known reproducing kernels are isometrically equivalent to a generalized Sobolev space. These examples further illustrate how we can rescale the Sobolev spaces by the vector distributional operator $\mathbf{P}$. Introducing the notion of scale as part of the definition of a generalized Sobolev space may help us to choose the "best" kernel function for kernel-based approximation methods.Comment: Update version of the publish at Num. Math. closed to Qi Ye's Ph.D. thesis (\url{http://mypages.iit.edu/~qye3/PhdThesis-2012-AMS-QiYe-IIT.pdf}