Forecasting of Atlantic tropical cyclones using a kilo-member ensemble

Department Head: Jeffrey L. Collett.2004 Summer.Includes bibliographical references (pages [175]-180).The past 30 years have witnessed steady improvements in the skill of tropical cyclone track forecasts. These increases have been largely driven by improved numerical weather prediction models and increased surveillance of the storm environment through aircraft reconnaissance and satellite remote sensing. The skill of deterministic track forecasts from full-physics models is gradually approaching the theoretical limit of predictability that arises due to the atmosphere's chaotic nature and limitations in determining the initial state. To make further progress, it is necessary to treat the uncertainty of the initial condition. One practical approach is to sample this uncertainty by perturbing the initial state. The resulting suite of forecasts that result from integrating such perturbations is known as an ensemble. This thesis describes the design, implementation, and evaluation of a semi-operational ensemble forecasting system using an efficient multigrid barotropic vorticity equation model (MBAR). Five perturbation classes are used to simulate uncertainties in the storm environment and vortex structure. Uncertainties in the storm environment are simulated by using the background environmental flow evolutions provided by the NCEP Global Forecasting System (GFS) ensemble forecasts. Several deep layer-mean wind averages account for uncertainty in the depth of the storm steering layer. Uncertainties in the decomposition of the tropical atmosphere's vertical modes are simulated by varying the model equivalent phase speed. Finally, uncertainties in the vortex structure are simulated by varying the vortex size and storm motion vector. Each perturbation in a given class is cross-multiplied with all other perturbations of other classes to obtain an ensemble with 1980 members. One of the fundamental questions addressed by this research is whether such cross-multiplication increases the degrees of freedom in the ensemble. The ensemble is run for 294 cases from the 2001-2003 Atlantic hurricane seasons. Theory dictates that a properly-perturbed ensemble should, on average, be more accurate than any single ensemble member, but it was found that the kilo-ensemble mean forecast did not demonstrate substantial improvement over the control forecast. However, the ensemble mean did show substantial skill relative to the five-day climatology and persistence model (CLP5) throughout the 120-h forecast period. The ensemble mean spread (the mean distance of the individual members from the ensemble mean), x-bias, and y-bias statistics are also evaluated. Probabilistic interpretations are valid with an ensemble of this size, so cumulative strike probabilities are calculated explicitly from the kilo-ensemble output. In a related possibilistic interpretation, the ensemble can be looked upon as mapping out the subspace of all possible storm tracks, so the reliability of this ensemble envelope is examined. Finally, if the ensemble can accurately simulate the uncertainties in the dynamical system, then there should be a positive relationship between ensemble mean spread and the error of the ensemble mean forecast. A strong relationship allows useful forecasts of forecast skill to be made at the time of the forecast. The kilo-member ensemble was found to have a weak spread-error relationship that peaks at 60 h

EFFECT OF INBREEDING ON LOIN AND FAT DEPTH IN HUNGARIAN LANDRACE PIGS

Pedigree and field test data - collected between 1997-2005 - were analyzed in a group of 68062 Hungarian Landrace pigs. The analysed traits were loin depth (LD), fat depth1 (FD1) and fat depth2 (FD2). In the present study inbreeding coefficients, pedigree completeness (complete generation equivalents) and inbreeding depression for LD, FD1 and FD2 were estimated. Increasing number of generations that were considered in the pedigree the estimated inbreeding coefficients did not change after the 5th generation, but pedigree completeness was continuously increasing. The estimated inbreeding depression for LD, FD1 and FD2 were different applying 5 different models but the magnitude of the differences was small. Increasing inbreeding coefficient by 10% caused LD decrease by 0.084 mm, the FD1 by 0.062 mm and did not affect FD2. It can be concluded that the estimated inbreeding depression was low and substantial depression can not be expected in the near future. However, the low level of inbreeding of the studied population can partly be explained by the short pedigrees. This suggests that Hungarian pig breeders may often import breeding animals or carry out herd replacements rather than apply within group selection

EFFECT OF INBREEDING ON LOIN AND FAT DEPTH IN HUNGARIAN LANDRACE PIGS

Pedigree and field test data - collected between 1997-2005 - were analyzed in a group of 68062 Hungarian Landrace pigs. The analysed traits were loin depth (LD), fat depth1 (FD1) and fat depth2 (FD2). In the present study inbreeding coefficients, pedigree completeness (complete generation equivalents) and inbreeding depression for LD, FD1 and FD2 were estimated. Increasing number of generations that were considered in the pedigree the estimated inbreeding coefficients did not change after the 5th generation, but pedigree completeness was continuously increasing. The estimated inbreeding depression for LD, FD1 and FD2 were different applying 5 different models but the magnitude of the differences was small. Increasing inbreeding coefficient by 10% caused LD decrease by 0.084 mm, the FD1 by 0.062 mm and did not affect FD2. It can be concluded that the estimated inbreeding depression was low and substantial depression can not be expected in the near future. However, the low level of inbreeding of the studied population can partly be explained by the short pedigrees. This suggests that Hungarian pig breeders may often import breeding animals or carry out herd replacements rather than apply within group selection

An adjustable law of motion for relativistic spherical shells

A classical and a relativistic law of motion for an advancing shell are deduced applying the thin layer approximation. A new parameter connected with the quantity of absorbed matter in the expansion is introduced; this allows of matching theory and observation.Comment: 15 pages, 10 figures and article in press; Central European Journal of Physics 201

The significance of lipid composition for membrane activity: new concepts and ways of assessing function

In the last decade or so, it has been realised that membranes do not just have a lipid-bilayer structure in which proteins are embedded or with which they associate. Structures are dynamic and contain areas of heterogeneity which are vital for their formation. In this review, we discuss some of the ways in which these dynamic and heterogeneous structures have implications during stress and in relation to certain human diseases. A particular stress is that of temperature which may instigate adaptation in poikilotherms or appropriate defensive responses during fever in mammals. Recent data emphasise the role of membranes in sensing temperature changes and in controlling a regulatory loop with chaperone proteins. This loop seems to need the existence of specific membrane microdomains and also includes association of chaperone (heat stress) proteins with the membrane. The role of microdomains is then discussed further in relation to various human pathologies such as cardiovascular disease, cancer and neurodegenerative diseases. The concept of modifying membrane lipids (lipid therapy) as a means for treating such pathologies is then introduced. Examples are given when such methods have been shown to have benefit. In order to study membrane microheterogeneity in detail and to elucidate possible molecular mechanisms that account for alteration in membrane function, new methods are needed. In the second part of the review, we discuss ultra-sensitive and ultra-resolution imaging techniques. These include atomic force microscopy, single particle tracking, single particle tracing and various modern fluorescence methods. Finally, we deal with computing simulation of membrane systems. Such methods include coarse-grain techniques and Monte Carlo which offer further advances into molecular dynamics. As computational methods advance they will have more application by revealing the very subtle interactions that take place between the lipid and protein components of membranes – and which are so essential to their function

Membrane fluidity matters: Hyperthermia from the aspects of lipids and membranes

Hyperthermia is a promising treatment modality for cancer in combination both with radio- and chemotherapy. In spite of its great therapeutic potential, the underlying molecular mechanisms still remain to be clarified. Due to lipid imbalances and 'membrane defects' most of the tumour cells possess elevated membrane fluidity. However, further increasing membrane fluidity to sensitise to chemo-or radiotherapy could have some other effects. In fact, hyperfluidisation of cell membrane induced by membrane fluidiser initiates a stress response as the heat shock protein response, which may modulate positively or negatively apoptotic cell death. Overviewing some recent findings based on a technology allowing direct imaging of lipid rafts in live cells and lipidomics, novel aspects of the intimate relationship between the 'membrane stress' of tumour cells and the cellular heat shock response will be highlighted. Our findings lend support to both the importance of membrane remodelling and the release of lipid signals initiating stress protein response, which can operate in tandem to control the extent of the ultimate cellular thermosensitivity. Overall, we suggest that the fluidity variable of membranes should be used as an independent factor for predicting the efficacy of combinational cancer therapies

Nanofibrous solid dosage form of living bacteria prepared by electrospinning

The aim of this work was to investigate the suitability of electrospinning for biodrug delivery and to develop an electrospinning-based method to produce vaginal drug delivery systems. Lactobacillus acidophilus bacteria were encapsulated into nanofibers of three different polymers (polyvinyl alcohol and polyvinylpyrrolidone with two different molar masses). Shelf life of the bacteria could be enhanced by the exclusion of water and by preparing a solid dosage form, which is an advantageous and patient-friendly way of administration. The formulations were stored at –20, 7 and 25°C, respectively. Viability testing showed that the nanofibers can provide long term stability for huge amounts of living bacteria if they are kept at (or below) 7°C. Furthermore, all kinds of nanowebs prepared in this work dissolved instantly when they got in contact with water, thus the developed biohybrid nanowebs can provide new potential ways for curing bacterial vaginosis

Dihydropyridine derivatives modulate heat shock responses and have a neuroprotective effect in a transgenic mouse model of Alzheimer’s disease

Heat shock proteins (Hsps) have chaperone activity and play a pivotal role in the homeostasis of proteins by preventing misfolding, by clearing aggregated and damaged proteins from cells and by maintaining proteins in an active state. Alzheimer’s disease (AD) is thought to be caused by β- amyloid peptide that triggers tau hyperphosphorylation, which is neurotoxic. Although proteostasis capacity declines with age and facilitates the manifestation of neurodegenerative diseases such as AD, the upregulation of chaperones improves prognosis. Our research goal is to identify potent Hsp co-inducers that enhance protein homeostasis for the treatment of AD, especially 1,4-dihydropyridine derivatives optimized for their ability to modulate cellular stress responses. Based on favorable toxicological data and Hsp co-inducing activity, LA1011 was selected for the in vivo analysis of its neuroprotective effect in the APPxPS1 mouse model of AD. Here, we report that 6 months of LA1011 administration effectively improved the spatial learning and memory functions in wild type mice and eliminated neurodegeneration in double mutant mice. Furthermore, Hsp co-inducer therapy preserves the number of neurons, increases dendritic spine density, and reduces tau pathology and amyloid plaque formation in transgenic AD mice. In conclusion, the Hsp co-inducer LA1011 is neuroprotective and therefore is a potential pharmaceutical candidate for the therapy of neurodegenerative diseases, particularly AD