Hierarchical formation of bulgeless galaxies II: Redistribution of angular momentum via galactic fountains

Within a fully cosmological hydrodynamical simulation, we form a galaxy which rotates at 140 km/s, and is characterised by two loose spiral arms and a bar, indicative of a Hubble Type SBc/d galaxy. We show that our simulated galaxy has no classical bulge, with a pure disc profile at z=1, well after the major merging activity has ended. A long-lived bar subsequently forms, resulting in the formation of a secularly-formed "pseudo" bulge, with the final bulge-to-total light ratio B/T=0.21. We show that the majority of gas which loses angular momentum and falls to the central region of the galaxy during the merging epoch is blown back into the hot halo, with much of it returning later to form stars in the disc. We propose that this mechanism of redistribution of angular momentum via a galactic fountain, when coupled with the results from our previous study which showed why gas outflows are biased to have low angular momentum, can solve the angular momentum/bulgeless disc problem of the cold dark matter paradigm.Comment: 9 Pages, 10 Figures, accepted MNRAS version. Comments welcom

A Comparison of Risk Exposure in Aquaculture and Agricultural Businesses

Agriculture and aquaculture have common features associated with their biological nature affecting risk exposure of the businesses. The aim of this paper is to compare risk exposure in salmon farming and agricultural enterprises in Norway by using an implicit error component model to examine the risk structure of yields, prices and economic returns at the farm level. Results indicate a higher farm-level year-to-year variability in yields, prices and economic returns in salmon farming than in agricultural enterprises. The variability in livestock enterprises was generally lower than for crop enterprises. Return on assets was highest in salmon farming with an average annual return of 9.2%. All of the agricultural farm types exhibited a negative average return on assets on average. Stochastic dominance tests of the distribution of economic returns from aquaculture and agricultural farm types showed salmon farming to be the most risk efficient alternative and salmon farming was most attractive from an investor’s perspective.Risk analysis, variability, Norway, Risk and Uncertainty,

Nighttime observations of thunderstorm electrical activity from a high altitude airplane

Nocturnal thunderstorms were observed from above and features of cloud structure and lightning which are not generally visible from the ground are discussed. Most, lightning activity seems to be associated with clouds with strong convective cauliflower tops. In both of the storms lightning channels were visible in the clear air above the cloud. It is shown that substances produced by thunderstorm electrical discharges can be introduced directly into the stratosphere. The cause and nature of the discharges above the cloud are not clear. They may be produced by accumulations of space charge in the clear air above the cloud. The discharges may arise solely because of the intense electric fields produced by charges within the cloud. In the latter case the ions introduced by these discharges will increase the electrical conductivity of the air above the cloud and increase the conduction current that flows from the cloud to the electrosphere. More quantitative data at higher resolution may show significant spectral differences between cloud to ground and intracloud strokes. It is shown that electric field change data taken with an electric field change meter mounted in an airplane provide data on lightning discharges from above that are quite similar to those obtained from the ground in the past. The optical signals from dart leaders, from return strokes, and from continuing currents are recognizable, can be used to provide information on the fine structure of lightning, and can be used to distinguish between cloud to ground and intracloud flashes

Quality of life of chronic stable angina patients 4 years after coronary angioplasty or coronary artery bypass surgery

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72244/1/j.1365-2796.2001.00782.x.pd

Hierarchical formation of bulgeless galaxies - II. Redistribution of angular momentum via galactic fountains

Within a fully cosmological hydrodynamical simulation, we form a galaxy which rotates at 140 km s−1, and it is characterized by two loose spiral arms and a bar, indicative of a Hubble-type SBc/d galaxy. We show that our simulated galaxy has no classical bulge, with a pure disc profile at z = 1, well after the major merging activity has ended. A long-lived bar subsequently forms, resulting in the formation of a secularly formed ‘pseudo-'bulge, with the final bulge-to-total light ratio of 0.21. We show that the majority of gas which loses angular momentum and falls to the central region of the galaxy during the merging epoch is blown back into the hot halo, with much of it returning later to form stars in the disc. We propose that this mechanism of redistribution of angular momentum via a galactic fountain, when coupled with the results from our previous study which showed why gas outflows are biased to have low angular momentum, can solve the angular momentum/bulgeless disc problem of the cold dark matter paradig

Exploration of transitional life events in individuals with Friedreich ataxia: Implications for genetic counseling

<p>Abstract</p> <p>Background</p> <p>Human development is a process of change, adaptation and growth. Throughout this process, transitional events mark important points in time when one's life course is significantly altered. This study captures transitional life events brought about or altered by Friedreich ataxia, a progressive chronic illness leading to disability, and the impact of these events on an affected individual's life course.</p> <p>Methods</p> <p>Forty-two adults with Friedreich ataxia (18-65y) were interviewed regarding their perceptions of transitional life events. Data from the interviews were coded and analyzed thematically using an iterative process.</p> <p>Results</p> <p>Identified transitions were either a direct outcome of Friedreich ataxia, or a developmental event altered by having the condition. Specifically, an awareness of symptoms, fear of falling and changes in mobility status were the most salient themes from the experience of living with Friedreich ataxia. Developmental events primarily influenced by the condition were one's relationships and life's work.</p> <p>Conclusions</p> <p>Friedreich ataxia increased the complexity and magnitude of transitional events for study participants. Transitional events commonly represented significant loss and presented challenges to self-esteem and identity. Findings from this study help alert professionals of potentially challenging times in patients' lives, which are influenced by chronic illness or disability. Implications for developmental counseling approaches are suggested for genetic counseling.</p> <p>Background</p> <p>Human development can be described in terms of key transitional events, or significant times of change. Transitional events initiate shifts in the meaning or direction of life and require the individual to develop skills or utilize coping strategies to adapt to a novel situation <abbrgrp><abbr bid="B1">1</abbr><abbr bid="B2">2</abbr></abbrgrp>. A successful transition has been defined as the development of a sense of mastery over the changed event <abbrgrp><abbr bid="B3">3</abbr></abbrgrp>.</p> <p>Transitions can be influenced by a variety of factors including one's stage of development, such as graduation from high school, historical events, including war, and idiosyncratic factors, such as health status <abbrgrp><abbr bid="B4">4</abbr><abbr bid="B5">5</abbr></abbrgrp>. Of particular interest in the present study are transitional life events, brought about or altered by progressive chronic illness and disability, and the impact of these events on the lives of affected individuals.</p> <p>It has been recognized that the clinical characteristics of a chronic illness or disability may alter the course and timing of many developmentally-related transitional events <abbrgrp><abbr bid="B6">6</abbr></abbrgrp>. For example, conditions associated with a shortened lifespan may cause an individual to pursue a career with a shorter course of training <abbrgrp><abbr bid="B6">6</abbr></abbrgrp>. Specific medical manifestations may also promote a lifestyle incongruent with developmental needs <abbrgrp><abbr bid="B6">6</abbr><abbr bid="B7">7</abbr></abbrgrp>. For example, an adolescent with a disability may have difficulty achieving autonomy because of his/her physical dependence on others.</p> <p>In addition to the aforementioned effects of chronic illness and disability on developmentally-related transitional events, a growing body of literature has described disease-related transitional events: those changes that are a direct result of chronic illness and disability. Diagnosis has received attention as being a key disease-related transitional event <abbrgrp><abbr bid="B8">8</abbr><abbr bid="B9">9</abbr></abbrgrp>. Studies have also noted other disease transitions related to illness trajectory <abbrgrp><abbr bid="B10">10</abbr></abbrgrp>, as the clinical features of the disease may require the individual to make specific adaptations. Disease-related events have also been described in terms of accompanying psychological processes, such as one's awareness of differences brought about by illness <abbrgrp><abbr bid="B11">11</abbr></abbrgrp>.</p> <p>While disease-related events are seemingly significant, the patient's perception of the events is varied. Some events may be perceived as positive experiences for the individual. For example, a diagnosis may end years of uncertainty. Some individuals may perceive these transitional events as insignificant, as they have accommodated to the continual change brought about by a chronic disease <abbrgrp><abbr bid="B12">12</abbr><abbr bid="B13">13</abbr></abbrgrp>.</p> <p>The aforementioned impact of disability and chronic illness on transitional events may create psychological stress. Developed by Lazarus and Folkman, the Transitional Model of Stress and Coping describes the process of adaptation to a health condition <abbrgrp><abbr bid="B14">14</abbr></abbrgrp>. This model purports that individuals first appraise a stressor and then utilize a variety of coping strategies in order to meet the stressor's demands <abbrgrp><abbr bid="B14">14</abbr></abbrgrp>. Thus, in the context of chronic illness, the ability of the individual to cope successfully with the stress of a health threat contributes to the process of overall adaptation to the condition.</p> <p>The process of adaptation can be more complex when the chronic illness or disability is progressive. Each transition brought about or altered by the disability may also represent additional loss, including the loss of future plans, freedom in social life and the ability to participate in hobbies <abbrgrp><abbr bid="B15">15</abbr></abbrgrp>. These losses may be accompanied by grief, uncertainty, and a continual need for adaptation <abbrgrp><abbr bid="B16">16</abbr><abbr bid="B17">17</abbr></abbrgrp>.</p> <p>Friedreich ataxia (FRDA) is one example of a progressive disorder, leading to adolescent and adult onset disability. To better understand patients' perceptions of key transitional events and the factors perceived to facilitate progression through these events, individuals with FRDA were interviewed.</p> <p>FRDA is a rare, progressive, neurodegenerative disorder affecting approximately one in 30,000 people in the United States <abbrgrp><abbr bid="B18">18</abbr></abbrgrp>. It equally affects both men and women. Individuals with FRDA experience progressive muscle weakness and loss of coordination in the arms and legs. For most patients, ataxia leads to motor incapacitation and full-time use of a wheelchair, commonly by the late teens or early twenties. Other complications such as vision and hearing impairment, dysarthria, scoliosis, diabetes mellitus and hypertrophic cardiomyopathy may occur <abbrgrp><abbr bid="B19">19</abbr><abbr bid="B20">20</abbr></abbrgrp>. Cardiomyopathy and respiratory difficulties often lead to premature death at an average age of 37 years <abbrgrp><abbr bid="B21">21</abbr></abbrgrp>. Currently, there are no treatments or cures for FRDA. Little is known about the specific psychological or psychosocial effects of the condition.</p> <p>FRDA is an autosomal recessive condition. The typical molecular basis of Friedreich ataxia is the expansion of a GAA trinucleotide repeat in both copies of the <it>FXN </it>gene <abbrgrp><abbr bid="B22">22</abbr></abbrgrp>. Age of onset usually occurs in late childhood or early adolescence. However, the availability of genetic testing has identified affected individuals with an adult form of the condition. This late-onset form is thought to represent approximately 10-15% of the total FRDA population <abbrgrp><abbr bid="B23">23</abbr></abbrgrp>.</p> <p>Health care providers of individuals with progressive, neurodegenerative disorders can help facilitate their patients' progression through transitional events. Data suggest that improvements should be made in the care of these individuals. Shaw et al. <abbrgrp><abbr bid="B24">24</abbr></abbrgrp> found that individualized care that helps to prepare patients for transition is beneficial. Beisecker et al. <abbrgrp><abbr bid="B25">25</abbr></abbrgrp> found that patients desire not only physical care from their providers, but also emotional and psychosocial support.</p> <p>Genetic counselors have an important opportunity to help patients with neuromuscular disorders progress through transitional events, as several of these conditions have a genetic etiology. Genetic counselors in pediatric and adult settings often develop long-term relationships with patients, due to follow-up care. This extended relationship is becoming increasingly common as genetic counselors move into various medical sub-specialties, such as neurology, ophthalmology, oncology and cardiology.</p> <p>The role of the genetic counselor in addressing the psychosocial needs of patients has been advocated, but rarely framed in the context of developmental events <abbrgrp><abbr bid="B26">26</abbr></abbrgrp>. Data suggest that patients may not expect a genetic counselor to address psychosocial needs <abbrgrp><abbr bid="B27">27</abbr></abbrgrp>. In a survey of genetic counseling patients, Wertz <abbrgrp><abbr bid="B28">28</abbr></abbrgrp> found a majority of respondents understood genetic conditions to have a moderate to serious effect on family life and finances, while almost half perceived there to be an effect on the spouse, quality of life, and the relationship between home and work. However, these topics were reportedly not discussed within genetic counseling sessions <abbrgrp><abbr bid="B27">27</abbr><abbr bid="B28">28</abbr></abbrgrp>. Overall, there is limited information about the experiences of transitional life events in FRDA, as well as a lack of recommendations for genetic counselors and other health care providers to assist patients through these events.</p> <p>Our study investigated perceptions of patients with Friedreich ataxia to 1) identify key transitional events and specific needs associated with events; 2) describe perception of factors to facilitate progression through the identified events; and 3) explore the actual or potential role of the health care provider in facilitating adaptation to the identified events. Data were used to make suggestions for developmental genetic counseling approaches in the context of ongoing care of clients with hereditary, progressive, neurodegenerative conditions.</p

Thin disc, Thick Disc and Halo in a Simulated Galaxy

Within a cosmological hydrodynamical simulation, we form a disc galaxy with sub- components which can be assigned to a thin stellar disc, thick disk, and a low mass stellar halo via a chemical decomposition. The thin and thick disc populations so selected are distinct in their ages, kinematics, and metallicities. Thin disc stars are young (<6.6 Gyr), possess low velocity dispersion ({\sigma}U,V,W = 41, 31, 25 km/s), high [Fe/H], and low [O/Fe]. The thick disc stars are old (6.6<age<9.8 Gyrs), lag the thin disc by \sim21 km/s, possess higher velocity dispersion ({\sigma}U,V,W = 49, 44, 35 km/s), relatively low [Fe/H] and high [O/Fe]. The halo component comprises less than 4% of stars in the "solar annulus" of the simulation, has low metallicity, a velocity ellipsoid defined by ({\sigma}U,V,W = 62, 46, 45 km/s) and is formed primarily in-situ during an early merger epoch. Gas-rich mergers during this epoch play a major role in fuelling the formation of the old disc stars (the thick disc). This is consistent with studies which show that cold accretion is the main source of a disc galaxy's baryons. Our simulation initially forms a relatively short (scalelength \sim1.7 kpc at z=1) and kinematically hot disc, primarily from gas accreted during the galaxy's merger epoch. Far from being a competing formation scenario, migration is crucial for reconciling the short, hot, discs which form at high redshift in {\Lambda}CDM, with the properties of the thick disc at z=0. The thick disc, as defined by its abundances maintains its relatively short scale-length at z = 0 (2.31 kpc) compared with the total disc scale-length of 2.73 kpc. The inside-out nature of disc growth is imprinted the evolution of abundances such that the metal poor {\alpha}-young population has a larger scale-length (4.07 kpc) than the more chemically evolved metal rich {\alpha}-young population (2.74 kpc).Comment: Submitted to MNRAS. This version after helpful referee comments. Comments welcome to [email protected]

A Search for Instantons at HERA

A search for QCD instanton (I) induced events in deep-inelastic scattering (DIS) at HERA is presented in the kinematic range of low x and low Q^2. After cutting into three characteristic variables for I-induced events yielding a maximum suppression of standard DIS background to the 0.1% level while still preserving 10% of the I-induced events, 549 data events are found while 363^{+22}_{-26} (CDM) and 435^{+36}_{-22} (MEPS) standard DIS events are expected. More events than expected by the standard DIS Monte Carlo models are found in the data. However, the systematic uncertainty between the two different models is of the order of the expected signal, so that a discovery of instantons can not be claimed. An outlook is given on the prospect to search for QCD instanton events using a discriminant based on range searching in the kinematical region Q^2\gtrsim100\GeV^2 where the I-theory makes safer predictions and the QCD Monte Carlos are expected to better describe the inclusive data.Comment: Invited talk given at the Ringberg Workshop on HERA Physics on June 19th, 2001 on behalf of the H1 collaboratio