Techniques for Identification of Left Ventricular Asynchrony for Cardiac Resynchronization Therapy in Heart Failure

The most recent treatment option of medically refractory heart failure includes cardiac resynchronization therapy (CRT) by biventricular pacing in selected patients in NYHA functional class III or IV heart failure. The widely used marker to indicate left ventricular (LV) asynchrony has been the surface ECG, but seems not to be a sufficient marker of the mechanical events within the LV and prediction of clinical response. This review presents an overview of techniques for identification of left ventricular intra- and interventricular asynchrony. Both manuscripts for electrical and mechanical asynchrony are reviewed, partly predicting response to CRT. In summary there is still no gold standard for assessment of LV asynchrony for CRT, but both traditional and new echocardiographic methods have shown asynchronous LV contraction in heart failure patients, and resynchronized LV contraction during CRT and should be implemented as additional methods for selecting patients to CRT

An Industry-University Partnership Case Study

At many universities, senior undergraduate mechanical engineers work in teams on industry-sponsored capstone design projects. These projects provide an excellent opportunity for students to synthesize their courses, work with the more realistic deadlines and expectations of industry, and interact with company representatives. It also give industrial partners a chance to become educational partners with the university, preview potential new hires, and complete some noncritical projects at low cost. This paper presents a case study of a successful six-year partnership between the Automotive Bumper Project committee of the American Iron & Steel Institute (AISI) and a mechanical engineering department. The AISI Bumper Project has sponsored seven senior capstone design projects and three master’s projects, providing excellent educational opportunities for twenty-five students. The projects ranged from specific vehicle bumper designs to building and testing a high-energy pendulum impact tester. The university benefited from this long-term relationship by gaining relevant student projects, supporting graduate students, and retaining a connection with industry. The industry consortium benefited by encouraging the study of topics of interest (steel design, impact analysis) at the undergraduate level, receiving ‘outside-the-box’ design concepts, and learning how bumpers may be affected by future trends. The costs on both sides were kept low, enabling most of the funds to go directly toward hardware so the students could build and test their designs

Investment Appraisal At Imperfect Capital Markets

Investment decisions are of vital importance to all companies. Thus, effective appraisal methods are most important tools to support the decision-making. Among the most popular methods are the Net Present Value Method, the Internal Rate of Return Method and the Annuity Method, which explicitly consider the time value of money and can be characterized by the assumption of a uniform rate and are connected with the assumption of a perfect capital market.Aiming at a decision-making process closer to real business life we describe an  investment appraisal method that assumes different credit and debtor interest rates, i.e., that is usable in imperfect capital markets. We exemplify investment appraisal in this market form with a method which visualizes any financial implications in an environment with a high number of different credit and debt interest rates, borrowing lines and other restrictions.  The usage of this method is shown at examples and the appraisal of single investment projects and the comparison of mutually exclusive projects are described

Networks in molecular evolution

Networks are a common theme at all levels of molecular evolution: Networks of metastable states and their connecting saddle points determine structure and folding kinetics of biopolymers. Neutral networks in sequence space explain the evolvability of both nucleic acids and polypeptides by linking Darwinian selection with neutral drift. Interacting replicators, be they simple molecules or highly complex mammals, form intricate ecological networks that are crucial for their survival. Chemical reactions are collected in extensive metabolic networks by means of specific enzymes; both the enzymes and the chemical reaction network that they govern undergoes evolutionary changes. Networks of gene regulation, protein-protein interaction, and cell signaling form the physico-chemical basis for morphogenesis and development. The nervous systems of higher animals form another distinct level of network architecture. We are beginning to understand the structure and function of each of the individual levels in some detail. Yet, their interplay largely remains still in the dark

Comparing efficient computation methods for massless QCD tree amplitudes: Closed Analytic Formulae versus Berends-Giele Recursion

Recent advances in our understanding of tree-level QCD amplitudes in the massless limit exploiting an effective (maximal) supersymmetry have led to the complete analytic construction of tree-amplitudes with up to four external quark-anti-quark pairs. In this work we compare the numerical efficiency of evaluating these closed analytic formulae to a numerically efficient implementation of the Berends-Giele recursion. We compare calculation times for tree-amplitudes with parton numbers ranging from 4 to 25 with no, one, two and three external quark lines. We find that the exact results are generally faster in the case of MHV and NMHV amplitudes. Starting with the NNMHV amplitudes the Berends-Giele recursion becomes more efficient. In addition to the runtime we also compared the numerical accuracy. The analytic formulae are on average more accurate than the off-shell recursion relations though both are well suited for complicated phenomenological applications. In both cases we observe a reduction in the average accuracy when phase space configurations close to singular regions are evaluated. We believe that the above findings provide valuable information to select the right method for phenomenological applications.Comment: 22 pages, 9 figures, Mathematica package GGT.m and example notebook is included in submissio

Development and Validation of a Pedestrian Lower Limb Non-Linear 3-D finite Element Model

Lower limb injury is becoming an increasingly important concern in vehicle safety for both occupants and pedestrians. To enable vehicle manufacturers to better understand the biomechanical effects of design changes, it is deemed beneficial to employ a biomechanically fidelic finite element model of the human lower limb. The model developed in this study includes long bones (tibia, fibula, femur) and flat bone (patella) as deformable bodies. The pelvis and foot bones are modeled as rigid bodies connected to the femur and tibia/fibula via rotational spring-dashpots. The knee is defined by scanned bone surface geometry and is surrounded by the menisci, major ligaments, and patellar tendon. Finite elements used to model include 6- and 8-node solids for cartilage, menisci, surrounding muscles, and cancellous bone; 3- and 4-node shells for skin and cortical bone; and nonlinear spring-dashpots for ligaments. Anatomical, physiological, and material properties data are from the literature while the bone surface geometry was scanned by a commercial source. Validation against published cadaver test results consisted of tibia and femur 3-point bending (lateral-medial and anterior-posterior) and whole limb lateral knee shear. Validation was performed under both static and dynamic loading condition, until bone failure or ligament rupture. Additional dynamic validation with the lower limb in a seated orientation has not been completed, limiting current applications to the pedestrian impact condition. The validated models were employed to examine the effect of axial compressive force (the physiological condition) on tibia and femur lateral-medial and anterior-posterior bending under static conditions

Recording from an Identified Neuron Efficiently Reveals Hazard for Brain Function in Risk Assessment

Modern societies use a continuously growing number of chemicals. Because these are released into the environment and are taken up by humans, rigorous (but practicable) risk assessment must precede the approval of new substances for commerce. A number of tests is applicable, but it has been very difficult to efficiently assay the effect of chemicals on communication and information processing in vivo in the adult vertebrate brain. Here, we suggest a straightforward way to rapidly and accurately detect effects of chemical exposure on action potential generation, synaptic transmission, central information processing, and even processing in sensory systems in vivo by recording from a single neuron. The approach is possible in an identified neuron in the hindbrain of fish that integrates various sources of information and whose properties are ideal for rapid analysis of the various effects chemicals can have on the nervous system. The analysis uses fish but, as we discuss here, key neuronal functions are conserved and differences can only be due to differences in metabolism or passage into the brain, factors that can easily be determined. Speed and efficiency of the method, therefore, make it suitable to provide information in risk assessment, as we illustrate here with the effects of bisphenols on adult brain function