Atmospheric Patterns and Asian Typhoon Landfalls

The Western North Pacific Ocean (WNP) produces more frequent and intense tropical cyclones (TC) than anywhere else in the world, and these storms greatly impact society. This study examines synoptic scale atmospheric patterns and their effects on landfalling typhoons in Japan, Taiwan and Vietnam using composite analysis at upper and mid-levels of the atmosphere, as well as analyzing teleconnection impacts on tropical cyclone frequency, duration and intensity. Examined Best Track data (1946-2010) shows an increased likelihood of Taiwan landfalls earlier in the season, Japan landfalls mid-season, and Vietnam landfalls towards the end of the typhoon season. The formation locations also differed slightly, with storms that eventually made landfall in Japan forming further east than those that hit Taiwan and Vietnam. With knowledge of these spatial and temporal generalizations, in addition to ENSO phase, probabilities of landfall in a specific region can be established. Composite analysis shows the presence of an upper-level anticyclone in each of the three landfall locations. The overall consensus for all three landfall areas is the tendency for tracks to follow the periphery of the upper-level anticyclones toward their respective landfalls. Vector wind composites also supported the findings of the upper-air composites, clearly showing areas of little to no wind shear in the path of the typhoons, indicating a favorable environment for tropical systems. The vector wind analyses also depicted where the dominant steering mechanism was, usually areas of anticyclonic flow surrounding the ridges. Analysis of the spatiotemporal evolution for selected typhoons shows the development of these synoptic features and how they evolve in relation to the typhoon, in particular affecting its intensity. The effect of ENSO and MJO on tropical cyclone frequency and intensity was also investigated using a statistical and quantitative analysis. 83% of TC during El Nino conditions achieved typhoon strength, with 66% of those intensifying even further to 100 knots or greater. In comparison, about 57% of TC reached typhoon strength during La Nina, and 43% of those reached 100 knot winds. Although the total number of cyclones was equal for the selected El Nino and La Nina events, a Poisson regression showed that during El Nino, the number of typhoon days with winds of at least 100 knots increases by a factor of 3.22 over La Nina years, indicating that TC are more likely to intensify during an El Nino. The average per storm shows that there is roughly one extra day of at least 100 knot winds during an El Nino typhoon than a La Nina typhoon. TC activity during an MJO event seemed to be similar with that of La Nina conditions. This research has many broad implications in the fields of atmospheric, oceanic and social sciences. Being able to identify and understand the atmospheric patterns present during certain landfalls gives us the advantage of recognizing those conditions in the future and taking appropriate action. Comprehending the primary steering controls of typhoons on all spatial and temporal scales, along with their behaviors and inner dynamics, is imperative for forecasting improvements and advancement of our knowledge of the tropical climate system and its variability

Computational Studies of Molecular Mechanisms Mediating Protein Adsorption on Material Surfaces

Protein adsorption at material surfaces is a fundamental concept in many scientific applications ranging from the biocompatibility of implant materials in bioengineering to cleaning environmental material surfaces from toxic proteins in the area of biodefense. Understanding the molecular-level details of protein-surface interactions is crucial for controlling protein adsorption. While a range of experimental techniques has been developed to study protein adsorption, these techniques cannot produce the fundamental molecular-level information of protein adsorption. All-atom empirical force field molecular dynamics (MD) simulations hold great promise as a valuable tool for elucidating and predicting the mechanisms governing protein adsorption. However, current MD simulation methods have not been validated for this application. This research addresses three limitations of the standard MD when applied to the simulations of the protein-surface interactions: (1) representation of the force field parameters governing the interactions of protein amino acids with the material surface; (2) cluster analysis of ensembles of adsorbed protein states obtained in protein-adsorption simulations, in which in addition to the conformation the orientation of the sampled states is also important; and (3) simulation time to ensure a significant level of conformational sampling to cover the entire rough energy landscape of such a large molecular system as protein adsorption. This study, thus, attempted to further advance protein-adsorption simulation methods using high-density polyethylene as a model materials surface

On radiative damping in plasma-based accelerators

Radiative damping in plasma-based electron accelerators is analyzed. The electron dynamics under combined influence of the constant accelerating force and the classical radiation reaction force is studied. It is shown that electron acceleration cannot be limited by radiation reaction. If initially the accelerating force was stronger than the radiation reaction force then the electron acceleration is unlimited. Otherwise the electron is decelerated by radiative damping up to a certain instant of time and then accelerated without limits. Regardless of the initial conditions the infinite-time asymptotic behavior of an electron is governed by self-similar solution providing unlimited acceleration. The relative energy spread induced by the radiative damping decreases with time in the infinite-time limit

Torsion and bending of prismatic rods of hollow rectangular section

The torsion and bending of hollow rectangular beams was investigated without the requirement that wall thickness be small compared with the transverse dimensions. The limits of applicability of the usual Bredt formula are indicated for the case of a square hollow tube in torsion. Formulas are given for bending stresses at different parts of the cross section of a hollow rectangular beam

An ab-initio study of pyrrole and imidazole arylamides

Arylamide foldamers have been shown to have a number of biological and medicinal applications. For example, a class of pyrrole-imidazole polyamide foldamers is capable of binding specific DNA sequences and preventing development of various gene disorders, most importantly cancer. Molecular dynamics (MD) simulations can provide crucial details in understanding the atomic level events related to foldamer/DNA binding. An important first step in the accurate simulation of these foldamer/DNA systems is the reparametrization of force field parameters for torsion around the aryl-amide bonds. Here we highlight our Density Functional Theory (DFT) potential energy profiles and derived force field parameters for four aryl-amide bond types for the pyrrole and imidazole building blocks extensively used in foldamer design for the DNA-binding polyamides. These results contribute to developing of computational tools for an appropriate molecular modeling of pyrrole-imidazole polyamide/DNA binding, and provide an insight into the chemical factors that influence the flexibility of the pyrrole-imidazole polyamides, and their binding to DNA