Charged hadron beam therapy : fast computational physics methods

Charged hadron beams have been investigated for use in radiation therapy of cancer since the 1940s due to their unique potential to place tightly conformal radiation doses deep inside tissue. This is achieved by exploiting the phenomenon of the so-called Bragg peak. In both research and clinical settings, fast and accurate radiation calculations play a crucial role in charged hadron therapy physics. Unfortunately, physicists are often faced with the fundamental trade off of speed versus accuracy in their calculations. This dissertation addresses this trade off by presenting three computational physics methods for specific and general charged hadron beam therapy calculations. In this dissertation the pseudo-Monte Carlo method of track repeating is adapted for fast calculations of linear energy transfer (LET) and for fast estimation of dose in the peripheral regions of the target volume (i.e. secondary dose estimation). Additionally, the first proof-of-concept framework for carrying out massively distributed parallel Monte Carlo calculations for radiation therapy using cloud computing is presented. Performance and accuracy assessments of each calculation method are also presented

Radiation therapy calculations using an on-demand virtual cluster via cloud computing

Computer hardware costs are the limiting factor in producing highly accurate radiation dose calculations on convenient time scales. Because of this, large-scale, full Monte Carlo simulations and other resource intensive algorithms are often considered infeasible for clinical settings. The emerging cloud computing paradigm promises to fundamentally alter the economics of such calculations by providing relatively cheap, on-demand, pay-as-you-go computing resources over the Internet. We believe that cloud computing will usher in a new era, in which very large scale calculations will be routinely performed by clinics and researchers using cloud-based resources. In this research, several proof-of-concept radiation therapy calculations were successfully performed on a cloud-based virtual Monte Carlo cluster. Performance evaluations were made of a distributed processing framework developed specifically for this project. The expected 1/n performance was observed with some caveats. The economics of cloud-based virtual computing clusters versus traditional in-house hardware is also discussed. For most situations, cloud computing can provide a substantial cost savings for distributed calculations.Comment: 12 pages, 4 figure

A Prairie Dog Abatement Program in San Juan County, Utah

Four species of prairie dogs are native to the plains and plateaus of the western United States. The most abundant and widely distributed of these is the blacktailed prairie dog, (Cynomys ludovicianus). This species has been a frequent topic of discussion at previous Great Plains Wildlife Damage Control workshops. Black-tailed prairie dog ecology and management was the topic of a panel discussion held at the Fifth Great Plains Wildlife Damage Control Workshop, in Lincoln, Nebraska (Timm and Johnson 1982) and the theme topic at the Eighth Great Plains Wildlife Damage Control Workshop in Rapid City, South Dakota (Uresk et al. 1988). The remaining three prairie dog species, all in the white-tail group, occur in Utah. These are the white-tailed prairie dog (Cynomys leucurus) in eastern and northeastern Utah, the Zuni Or Gunnison\u27s prairie dog (C. gunnisonii) in southeastern Utah, and the Utah prairie dog (C. parvidens in southcentral Utah. Of these, the Utah prairie dog is federally recognized as a threatened species. Although the ecology of the white-tail prairie dog group has been studied, much of the information reported deals with behavioral aspects. Very few studies deal directly with population ecology (Longhurst 1944, Tileston and Lechleitner 1966, Clark 1977, Elmore et al. 1976, Menkens et al. 1988). Although aspects of white-tail group and black-tailed ecology may be similar, their life histories differ (Longhurst 1944, Tileston and Lechleitner 1966, Campbell and Clark 1981, Hoogland et al. 1988, Menkens et al. 1988). Knowledge of these differences are important in designing and implementing programs to manage the damage caused by species of the white-tail prairie dog group. The purpose of this paper therefore is twofold. First, I will review and compare the ecology of the white-tail prairie dog groups as they occur in Utah and the West to that of the black-tailed prairie dog. Secondly, I will discuss management of the damage caused by the white-tail prairie dog group in Utah through the implementation of coordinated county-wide abatement programs. This latter discussion will describe program efforts conducted in southeastern Utah\u27s San Juan County to manage damage associated with the Gunnison\u27s prairie dog

Autoencoder-based analytic continuation method for strongly correlated quantum systems

The single particle Green's function provides valuable information on the momentum and energy-resolved spectral properties for a strongly correlated system. In large-scale numerical calculations using quantum Monte Carlo (QMC), dynamical mean field theory (DMFT), including cluster-DMFT, one usually obtains the Green's function in imaginary-time $G(\tau)$. The process of inverting a Laplace transform to obtain the spectral function $A(\omega)$ in real-frequency is an ill-posed problem and forms the core of the analytic continuation problem. In this Letter, we propose to use a completely unsupervised autoencoder-type neural network to solve the analytic continuation problem. We introduce an encoder-decoder approach that, together with only minor physical assumptions, can extract a high-quality frequency response from the imaginary time domain. With a deeply tunable architecture, this method can, in principle, locate sharp features of spectral functions that might normally be lost using already well-established methods, such as maximum entropy (MaxEnt) methods. We demonstrate the strength of the autoencoder approach by applying it to QMC results of $G(\tau)$ for a single-band Hubbard model. The proposed method is general and can also be applied to other ill-posed inverse problems.Comment: 7 pages, 5 figures, supplemen

Challenges and opportunities for quantifying roots and rhizosphere interactions through imaging and image analysis

The morphology of roots and root systems influences the efficiency by which plants acquire nutrients and water, anchor themselves and provide stability to the surrounding soil. Plant genotype and the biotic and abiotic environment significantly influence root morphology, growth and ultimately crop yield. The challenge for researchers interested in phenotyping root systems is, therefore, not just to measure roots and link their phenotype to the plant genotype, but also to understand how the growth of roots is influenced by their environment. This review discusses progress in quantifying root system parameters (e.g. in terms of size, shape and dynamics) using imaging and image analysis technologies and also discusses their potential for providing a better understanding of root:soil interactions. Significant progress has been made in image acquisition techniques, however trade-offs exist between sample throughput, sample size, image resolution and information gained. All of these factors impact on downstream image analysis processes. While there have been significant advances in computation power, limitations still exist in statistical processes involved in image analysis. Utilizing and combining different imaging systems, integrating measurements and image analysis where possible, and amalgamating data will allow researchers to gain a better understanding of root:soil interactions

Biological Effects of Antiprotons Are Antiprotons a Candidate for Cancer Therapy?

2009 Status Report of AD-4 Experimen

Pathways to fatherhood: psychological well-being among Israeli gay fathers through surrogacy, gay fathers through previous heterosexual relationships, and heterosexual fathers

This study explored differences in psychological well-being as assessed by life satisfaction, parenthood satisfaction, depressive symptoms and the Big Five personality dimensions among 219 Israeli fathers; 76 gay men who had become fathers through a heterosexual relationship, 63 gay men who had become fathers through surrogacy, and 78 heterosexual men. After controlling for sociodemographic characteristics, gay fathers through surrogacy reported greater satisfaction with parenthood, greater satisfaction with their lives, and reported higher levels of extraversion when compared to heterosexual fathers. No significant differences emerged between the three groups on depressive symptoms, neuroticism, conscientiousness, agreeableness, and openness to experience. These findings emphasize the predominant similarities and some possible differences on psychological well-being between the different paths to fatherhood. This study is one of the first to compare several paths to fatherhood on psychological well-being, thus illuminating the contribution of fatherhood route to psychological well-being in an era where gay men are increasingly becoming fathers in diverse ways

Country-level and individual correlates of overweight and obesity among primary school children: a cross-sectional study in seven European countries.

BACKGROUND: The present study aims to estimate childhood overweight and obesity prevalence and their association with individual and population-level correlates in Eastern and Western European countries. METHODS: Data were obtained from the School Children Mental Health in Europe, a cross-sectional survey conducted in 2010 in Italy, Germany, the Netherlands, Romania, Bulgaria, Lithuania and Turkey. The sample consists of 5,206 school children aged 6 to 11 years old. Information on socio-demographics, children's height and weight, life-style and parental attitude were reported by the mothers. Country-level indicators were obtained through several data banks. Overweight and obesity in children were calculated according to the international age and gender-specific child Body Mass Index cut-off points. Multivariable logistic regression models included socio-demographic, lifestyle, mothers' attitude, and country-level indicators to examine the correlates of overweight. RESULTS: Overall prevalence was 15.6% (95% CI = 19.3-21.7%) for overweight and 4.9% (95% CI = 4.3-5.6%) for obesity. In overweight (including obesity), Romanian children had the highest prevalence (31.4%, 95% CI = 28.1-34.6%) and Italian the lowest (10.4%, 95% CI = 8.1-12.6%). Models in the pooled sample showed that being younger (aOR = 0.93, 95% = CI 0.87-0.97), male (aOR = 1.24, 95% CI = 1.07-1.43), an only child (aOR = 1.40, 95% CI = 1.07-1.84), spending more hours per week watching TV (aOR = 1.01, 95% CI =1.002-1.03), and living in an Eastern Country were associated with greater risk of childhood overweight (including obesity). The same predictors were significantly associated with childhood overweight in the model conducted in the Eastern region, but not in the West. Higher Gross Domestic Product and Real Domestic Product, greater number of motor and passenger vehicles, higher percentage of energy available from fat, and more public sector expenditure on health were also associated with lower risk for childhood overweight after adjusting for covariables in the pooled sample and in the east of Europe, but not in the West. CONCLUSIONS: Prevalence rates of overweight and obesity in school children is still high, especially in Eastern regions, with some socio-demographic factors and life-styles associated with being overweight. It is also in the Eastern region itself where better macro-economic indicators are related with lower rates of childhood overweight. This represents a public health concern that deserves special attention in those countries undertaking economic and political transitions

Search for squarks and gluinos in events with isolated leptons, jets and missing transverse momentum at s√=8 TeV with the ATLAS detector

The results of a search for supersymmetry in final states containing at least one isolated lepton (electron or muon), jets and large missing transverse momentum with the ATLAS detector at the Large Hadron Collider are reported. The search is based on proton-proton collision data at a centre-of-mass energy s√=8 TeV collected in 2012, corresponding to an integrated luminosity of 20 fb−1. No significant excess above the Standard Model expectation is observed. Limits are set on supersymmetric particle masses for various supersymmetric models. Depending on the model, the search excludes gluino masses up to 1.32 TeV and squark masses up to 840 GeV. Limits are also set on the parameters of a minimal universal extra dimension model, excluding a compactification radius of 1/R c = 950 GeV for a cut-off scale times radius (ΛR c) of approximately 30