302 research outputs found
The Money To Get Started - What Do Farm Boys Expect?
It takes a lot of capital to acquire and to operate an Iowa farm. The study of occupational plans and preferences of Iowa farm boys helps to indicate just how much influence capital needs have on their plans
Occupational plans of Iowa farm boys
This bulletin reports the findings of an exploratory study of the long-range occupational plans of Iowa farm boys in their senior year of high school. The primary objectives of the study were: (1) to relate the theory of choice to occupational planning, (2) to describe the occupational plans of the boys, (3) to determine the characteristics which differentiate boys who plan to farm from boys who plan nonfarm careers and (4) to appraise the relative importance of factors influencing farm-nonfarm occupational plans.
Application of the theory of choice to occupational planning resulted in three general hypotheses to explain why some farm boys plan to farm while others plan nonfarm occupations. These hypotheses involved individual differences in (1) occupational satisfaction functions (preference systems), (2) available resources and (3) the results expected from using given resources in farm and nonfarm employments. Various operational hypotheses derived from the general hypotheses were evaluated on the basis of evidence obtained from a state-wide sample of senior farm boys attending Iowa high schools in rural areas and cities under 25,000 population in the spring of 1959
What Careers for Farm Boys?
This is the first of a series of articles reporting the results of a study of the career preferences and plans and choices of farm boys. This article tells of career plans the boys made and of their immediate after high school plans
Design optimization of pixel sensors using device simulations for the phase-II CMS tracker upgrade
In order to address the problems caused by the harsh radiation environment during the high luminosity phase of the LHC (HL-LHC), all silicon tracking detectors (pixels and strips) in the CMS experiment will undergo an upgrade. And so to develop radiation hard pixel sensors, simulations have been performed using the 2D TCAD device simulator, SILVACO, to obtain design parameters. The effect of various design parameters like pixel size, pixel depth, implant width, metal overhang, p-stop concentration, p-stop depth and bulk doping density on the leakage current and critical electric field are studied for both non-irradiated as well as irradiated pixel sensors. These 2D simulation results of planar pixels are useful for providing insight into the behaviour of non-irradiated and irradiated silicon pixel sensors and further work on 3D simulation is underway. © 2015 Elsevier B.V
paediatric respiratory disease past present and future
Paediatric respiratory disease has changed in the past 20 yrs; we could fill a whole issue of the journal paying tribute to our famous forebears. We are posing new challenges to our colleagues in the field of adult respiratory disease. They have to learn to deal with conditions that 20 yrs ago were rare in the adult chest clinic, such as cystic fibrosis (CF) and the long-term consequences of premature birth and congenital malformations of the respiratory tract. Furthermore, studies in childhood are challenging pathophysiological concepts throughout life. The many great prospective birth cohort studies have shed light on the different patterns of wheezing, their risk factors and their evolution through childhood. Who would have thought it was good to be born in a barn! It is becoming increasingly clear that even for "adult" diseases, such as chronic obstructive pulmonary disease (COPD), antenatal and early life events are at least as important as smoking in adulthood 1. CF has become a disease also of adults 2. Although many factors have contributed, the main reason has been the development of expert special CF centres, a model increasingly adopted by adult teams. This can serve as a model for other diseases; how a well-structured multidisciplinary approach to treatment can translate into benefits for patients. Perhaps numerically the most important achievement is in the field of public health. The benefit of the decrease in invasive bacterial infections, due to vaccination programmes for infants, is among the most important achievements of the past. Other areas of change include the survival of ever smaller preterm neonates. These children are reaching adult life with impaired lung function and abnormal computed tomography scans. What will happen to their ageing lungs? Interstitial lung disease (ILD) is becoming increasingly well understood, with new genetic entities, such as
Modulated structures in electroconvection in nematic liquid crystals
Motivated by experiments in electroconvection in nematic liquid crystals with
homeotropic alignment we study the coupled amplitude equations describing the
formation of a stationary roll pattern in the presence of a weakly-damped mode
that breaks isotropy. The equations can be generalized to describe the planarly
aligned case if the orienting effect of the boundaries is small, which can be
achieved by a destabilizing magnetic field. The slow mode represents the
in-plane director at the center of the cell. The simplest uniform states are
normal rolls which may undergo a pitchfork bifurcation to abnormal rolls with a
misaligned in-plane director.We present a new class of defect-free solutions
with spatial modulations perpendicular to the rolls. In a parameter range where
the zig-zag instability is not relevant these solutions are stable attractors,
as observed in experiments. We also present two-dimensionally modulated states
with and without defects which result from the destabilization of the
one-dimensionally modulated structures. Finally, for no (or very small)
damping, and away from the rotationally symmetric case, we find static chevrons
made up of a periodic arrangement of defect chains (or bands of defects)
separating homogeneous regions of oblique rolls with very small amplitude.
These states may provide a model for a class of poorly understood stationary
structures observed in various highly-conducting materials ("prechevrons" or
"broad domains").Comment: 13 pages, 13 figure
Enabling Technologies for Silicon Microstrip Tracking Detectors at the HL-LHC
While the tracking detectors of the ATLAS and CMS experiments have shown
excellent performance in Run 1 of LHC data taking, and are expected to continue
to do so during LHC operation at design luminosity, both experiments will have
to exchange their tracking systems when the LHC is upgraded to the
high-luminosity LHC (HL-LHC) around the year 2024. The new tracking systems
need to operate in an environment in which both the hit densities and the
radiation damage will be about an order of magnitude higher than today. In
addition, the new trackers need to contribute to the first level trigger in
order to maintain a high data-taking efficiency for the interesting processes.
Novel detector technologies have to be developed to meet these very challenging
goals. The German groups active in the upgrades of the ATLAS and CMS tracking
systems have formed a collaborative "Project on Enabling Technologies for
Silicon Microstrip Tracking Detectors at the HL-LHC" (PETTL), which was
supported by the Helmholtz Alliance "Physics at the Terascale" during the years
2013 and 2014. The aim of the project was to share experience and to work
together on key areas of mutual interest during the R&D phase of these
upgrades. The project concentrated on five areas, namely exchange of
experience, radiation hardness of silicon sensors, low mass system design,
automated precision assembly procedures, and irradiations. This report
summarizes the main achievements
The ARAUCARIA project: Grid-Based Quantitative Spectroscopic Study of Massive Blue Stars in NGC55
The quantitative study of the physical properties and chemical abundances of
large samples of massive blue stars at different metallicities is a powerful
tool to understand the nature and evolution of these objects. Their analysis
beyond the Milky Way is challenging, nonetheless it is doable and the best way
to investigate their behavior in different environments. Fulfilling this task
in an objective way requires the implementation of automatic analysis
techniques that can perform the analyses systematically, minimizing at the same
time any possible bias.
As part of the ARAUCARIA project we carry out the first quantitative
spectroscopic analysis of a sample of 12 B-type supergiants in the galaxy NGC55
at 1.94 Mpc away. By applying the methodology developed in this work, we derive
their stellar parameters, chemical abundances and provide a characterization of
the present-day metallicity of their host galaxy.
Based on the characteristics of the stellar atmosphere/line formation code
FASTWIND, we designed and created a grid of models for the analysis of massive
blue supergiant stars. Along with this new grid, we implemented a spectral
analysis algorithm. Both tools were specially developed to perform fully
consistent quantitative spectroscopic analyses of low spectral resolution of
B-type supergiants in a fast and objective way.
We present the main characteristics of our FASTWIND model grid and perform a
number of tests to investigate the reliability of our methodology. The
automatic tool is applied afterward to a sample of 12 B-type supergiant stars
in NGC55, deriving the stellar parameters and abundances. The results indicate
that our stars are part of a young population evolving towards a red supergiant
phase. The derived chemical composition hints to an average metallicity similar
to the one of the Large Magellanic Cloud, with no indication of a spatial trend
across the galaxy.Comment: 19 pages, 12 figures and 9 tables. Accpeted for publication in A&
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