Yang-Mills theory a la string

A surface of codimension higher than one embedded in an ambient space possesses a connection associated with the rotational freedom of its normal vector fields. We examine the Yang-Mills functional associated with this connection. The theory it defines differs from Yang-Mills theory in that it is a theory of surfaces. We focus, in particular, on the Euler-Lagrange equations describing this surface, introducing a framework which throws light on their relationship to the Yang-Mills equations.Comment: 7 page

Effects of Age and Comorbidities on Intensive Care and 1-year Mortality after HeartMate 3 Implantation

Background: The use of left ventricular assist devices (LVAD) has been rapidly increasing in older people over the past two decades due to their availability as destination therapy. This study aimed to assess the effect of age and comorbidities on the intensive care unit (ICU) and 1-year mortality after HeartMate 3 LVAD implantation. Methods: From 2016 to 2023, all consecutive adult patients implanted with HeartMate 3 LVAD in our tertiary referral center were enrolled in the study. Patients were stratified according to their age at implantation into Group-1 (&lt;45 years), Group-2 (46–64 years), and Group-3 (&gt;65 years). The effect of age and comorbidities on ICU and 1-year mortality were assessed. Results: In total, 135 patients were included (mean age 54±13 years, 79% males). Baseline vital signs, comorbidities, and hemodynamic support were not different between age groups. The older population had significantly lower eGFR (p=0.025), ischemic cardiac diseases as the underlying heart problem (p&lt;0.001), and LVAD as destination therapy (p&lt;0.001). The mortality rate at the ICU and at one year were 90% and 83%, respectively. The median age of the patients who died in the ICU was significantly higher than 63 [56–65] years versus 57 years [49–62, p=0.034). However, age lost its significance with logistic regression analysis. Having a recent major myocardial infarct, high preoperative leukocyte count, and cardiopulmonary bypass time were independent risk factors for ICU mortality. On the other hand, age was an independent risk factor for one-year mortality. Conclusion: Older age predicts increased one-year but not ICU mortality after HeartMate 3 LVAD implantation, while recent major myocardial infarction, high preoperative leukocyte count, and longer cardiopulmonary bypass time were independent risk factors for ICU mortality. Careful patient selection is critical to optimize outcomes after HeartMate 3 LVAD implantation.</p

Hamiltonian Frenet-Serret dynamics

The Hamiltonian formulation of the dynamics of a relativistic particle described by a higher-derivative action that depends both on the first and the second Frenet-Serret curvatures is considered from a geometrical perspective. We demonstrate how reparametrization covariant dynamical variables and their projections onto the Frenet-Serret frame can be exploited to provide not only a significant simplification of but also novel insights into the canonical analysis. The constraint algebra and the Hamiltonian equations of motion are written down and a geometrical interpretation is provided for the canonical variables.Comment: Latex file, 14 pages, no figures. Revised version to appear in Class. Quant. Gra

Hamilton's equations for a fluid membrane: axial symmetry

Consider a homogenous fluid membrane, or vesicle, described by the Helfrich-Canham energy, quadratic in the mean curvature. When the membrane is axially symmetric, this energy can be viewed as an `action' describing the motion of a particle; the contours of equilibrium geometries are identified with particle trajectories. A novel Hamiltonian formulation of the problem is presented which exhibits the following two features: {\it (i)} the second derivatives appearing in the action through the mean curvature are accommodated in a natural phase space; {\it (ii)} the intrinsic freedom associated with the choice of evolution parameter along the contour is preserved. As a result, the phase space involves momenta conjugate not only to the particle position but also to its velocity, and there are constraints on the phase space variables. This formulation provides the groundwork for a field theoretical generalization to arbitrary configurations, with the particle replaced by a loop in space.Comment: 11 page

Composite p-Branes in Diverse Dimensions

We use a simple algebraic method to find a special class of composite p-brane solutions of higher dimensional gravity coupled with matter. These solutions are composed of n constituent p-branes corresponding n independent harmonic functions. A simple algebraic criteria of existence of such solutions is presented. Relations with D=11,10 known solutions are discussed.Comment: 11 pages, latex, emlines2.sty; corrections in Sect.

The Jang equation, apparent horizons, and the Penrose inequality

The Jang equation in the spherically symmetric case reduces to a first order equation. This permits an easy analysis of the role apparent horizons play in the (non)existence of solutions. We demonstrate that the proposed derivation of the Penrose inequality based on the Jang equation cannot work in the spherically symmetric case. Thus it is fruitless to apply this method, as it stands, to the general case. We show also that those analytic criteria for the formation of horizons that are based on the use of the Jang equation are of limited validity for the proof of the trapped surface conjecture.Comment: minor misprints correcte

City planning using integrated urban modeling Jeddah structure plan

This paper explores the use of weighted space syntax models to contribute to the process of integrated urban planning for Jeddah as part of a major planning project in the Saudi Arabia. The Municipality of Jeddah commissioned the production of an integrated suite of planning documents. These plans coordinate Strategic, Sub-Regional, Structural and Local plans across a citywide region and aim to provide a framework for sustainable urban growth and development over the next 20 years. This paper focuses on the space syntax methodologies used to aid urban planners to develop the Structure Plan and builds on the research used to develop the Sub-Regional Plan (Karimi et al, 2015). The Structure Plan studied how the urban structure of the city could accommodate the growth of population by about three million over the next 20 years. This included developing and testing a centres strategy to distribute population, employment and supporting facilities along with a public transport strategy for the city. For analysing the potential and requirements of the city, an Integrated Urban Model (IUM) was constructed to combine the spatial network with land use, population, employment and public transport. The aim of this model was to test the impact of changes in the distribution of population and employment. It also allowed the assessment of public transport alignments. The IUM is a key design tool for planning and optimising the relationships between population, employment and public transport. It was also used to provide a benchmarking methodology to compare options. Because the model links people to employment using the spatial network and public transport, the performance of options can be expressed in terms of benefits to the city's population

Noether Currents for Bosonic Branes

We consider a relativistic brane propagating in Minkowski spacetime described by any action which is local in its worldvolume geometry. We examine the conservation laws associated with the Poincar\'e symmetry of the background from a worldvolume geometrical point of the view. These laws are exploited to explore the structure of the equations of motion. General expressions are provided for both the linear and angular momentum for any action depending on the worldvolume extrinsic curvature. The conservation laws are examined in perturbation theory. It is shown how non-trivial solutions with vanishing energy-momentum can be constructed in higher order theories. Finally, subtleties associated with boundary terms are examined in the context of the brane Einstein-Hilbert action.Comment: 33 pages, Latex. Published in Annals of Physics 279, 126, 200

Microcirculation: Physiology, pathophysiology, and clinical application

This paper briefly reviews the physiological components of the microcirculation, focusing on its function in homeostasis and its central function in the realization of oxygen transport to tissue cells. Its pivotal role in the understanding of circulatory compromise in states of shock and renal compromise is discussed. Our introduction of hand-held vital microscopes (HVM) to clinical medicine has revealed the importance of the microcirculation as a central target organ in states of critical illness and inadequate response to therapy. Technical and methodological developments have been made in hardware and in software including our recent introduction and validation of automatic analysis software called MicroTools, which now allows point-of-care use of HVM imaging at the bedside for instant availability of functional microcirculatory parameters needed for microcirculatory targeted resuscitation procedures to be a reality

Examination of gutta-percha cones for microbial contamination during chemical use

OBJECTIVE: The aim of this study was to evaluate the degree of microbial contamination in packaged gutta-percha cones before and during use in clinical conditions. MATERIAL AND METHODS: Sealed packages of #15-40 gutta-percha cones were opened under aseptic laboratory conditions. Two gutta-percha cones from each size were randomly drawn and added to tubes containing glass beads and 750 µL of saline. The tubes were vortexed, serially diluted and samples of 250 µL were cultured on agar plates. The plates were incubated at 37ºC for 3 days and colonies were counted. The initially sampled packages were distributed to 12 final year dental students. The packages were collected at the end of the first and the third clinical practice days and sampled as described above. RESULTS: Baseline microbial counts did not exceed 3 CFU. At the end of the first and the third day, additional contamination was found in five and three of the packages, respectively. The ratio of contaminated packages at the first day and the third day was not significantly different (z-test; p >; 0.05). The numbers of microorganisms cultured at the first day (8 ± 9.9 CFU) and the third day (4.5 ± 8.3 CFU) were not significantly different (Wilcoxon signed-rank test; p >; 0.05). No significant correlation was found between the number of filled root canals and cultured microorganisms at either the first day (Spearman's rho; r = 0.481, p = 0.113) or the third day (r = -0.034, p = 0.917). CONCLUSIONS: Gutta-percha cones taken directly from manufacturer's sealed package harbored microorganisms. Clinical use of the packages has been found to be associated with additional contamination of the gutta-percha cones. The counts of cultured microorganisms did not correlate well with the number of filled root canals