6,595 research outputs found
Matanuska Valley Memoir
We acknowledge indebtedness to the historians and developers of Alaskana
who preceded us and provided much of the information we have compiled
into our account of the birth of a community. Many "old timers" from
the Valley provided valuable insight into situations they had experienced.
Mr. Roland Snodgrass, Mrs, June Murphy and Miss Dolores Pommier
assisted in compilation and preparation of background data. Mr. James
Hurley made available to us the ARRC unpublished files for compilation
of certain data. Various public officials aided us in many ways as we
worked· our way through recorded . history. Several old photos were
contributed by Mr. Walter Teeland of Wasilla and Mr. Don L. Irwin of
Palmer. Several persons in public and private life who know Alaskan
conditions have reviewed the manuscript and suggested improvements,
Special acknowledgement is due Don L. Irwin, Director of the Alaska
Agricultural Experiment Station, His vision and foresight were largely
responsible for the undertaking, His encouragement and advice bolstered
our lagging spirits before the long task was completed. He has read
each chapter critically and has assisted particularly with interpretation
of materials since 1935,The Matanuska Valley was created through action of ice, water and
wind. When the last glaciers retreated up the Susitna, the Knik and the
Matanuska valleys, vegetation began cove ring the scars, Over several
centuries a dense growth of trees and brush screened the land from Knik
Arm to the mountain slopes of the Talkeetna range . Here and there a
lake broke the uniform forest mantle. A salt marsh at the mouth of the
Matanuska River kept the rank undergrowth from reaching tide water,
A few low spots near the Little Susitna and other swampy areas supported
a thick cover of moss or grass.
The Valley, which really isn't a valley at all but a reworked foreland,
rises from the Matanuska River in a series of benches ranging in width
from a few hundred feet to more than a mile. Some areas are flat,
others are rolling. Soil depth varies from eight feet in thickness for
the region bordering the Matanuska River to a few inches in sections
west of Wasilla. The soil mantle, of windblown loessial materials, is
of relatively new geologic development, The Valley is bounded by the
Chugach Mountains on the east, the Talkeetnas on the north, the Susitna
Valley on the west and Knik Arm on the south. Winters are long but
usually not unduly severe; summers cool and relatively moist,
To this country came trappers, prospectors and traders in closing years
of the nineteenth century. Hordes of insects, difficult trails, sparse
population and great distance s from supply points discouraged many
potential residents, Those who stayed were interested primarily in the
Willow Creek gold field or the Matanuska coal deposits.
Another generation, an uneasy international situation and social crises
within the United States were required before the Matanuska Valley and
the rest of Upper Cook Inlet were ripe for use. This history of the
Valley is designed to trace the many human elements affecting the ebb
and flow of agricultural development here. It brings into focus many
problems that must be solved before new areas in Alaska can be settled
satisfactorily
Reliability of perceptions of voice quality: evidence from a problem asthma clinic population
<p>Introduction: Methods of perceptual voice evaluation have yet to achieve satisfactory consistency; complete acceptance of a recognised clinical protocol is still some way off.</p>
<p>Materials and methods: Three speech and language therapists rated the voices of 43 patients attending the problem asthma clinic of a teaching hospital, according to the grade-roughness-breathiness-asthenicity-strain (GRBAS) scale and other perceptual categories.</p>
<p>Results and analysis: Use of the GRBAS scale achieved only a 64.7 per cent inter-rater reliability and a 69.6 per cent intra-rater reliability for the grade component. One rater achieved a higher degree of consistency. Improved concordance on the GRBAS scale was observed for subjects with laryngeal abnormalities. Raters failed to reach any useful level of agreement in the other categories employed, except for perceived gender.</p>
<p>Discussion: These results should sound a note of caution regarding routine adoption of the GRBAS scale for characterising voice quality for clinical purposes. The importance of training and the use of perceptual anchors for reliable perceptual rating need to be further investigated.</p>
Behavioural compensation by drivers of a simulator when using a vision enhancement system
Technological progress is suggesting dramatic changes to the tasks of the driver, with the general aim of making driving environment safer. Before any of these technologies are implemented, empirical research is required to establish if these devices do, in fact, bring about the anticipated improvements. Initially, at least, simulated driving environments offer a means of conducting this research. The study reported here concentrates on the application of a vision enhancement (VE) system within the risk homeostasis paradigm. It was anticipated, in line with risk homeostasis theory, that drivers would compensate for the reduction in risk by increasing speed. The results support the hypothesis although, after a simulated failure of the VE system, drivers did reduce their speed due to reduced confidence in the reliability of the system
Surgery and paediatric inflammatory bowel disease
The incidence of paediatric Crohn’s disease (CD) and ulcerative colitis (UC) is increasing. Surgical intervention is required during childhood in approximately 25% of children diagnosed with CD, and for 10% of those diagnosed with UC. Although there is evidence that the rate of surgical intervention undertaken in children is decreasing since the introduction of biologic therapy, this may only represent a delay rather than true reversal of the risk of surgery. Surgery for CD is not curative and limited resection is the key principle thus preserving bowel length. For UC, subtotal colectomy is relatively curative; ileo-anal pouch anastomosis can be performed to restore bowel continuity
Task analysis for error identification: Theory, method and validation
This paper presents the underlying theory of Task Analysis for Error Identification. The aim is to illustrate the development of a method that has been proposed for the evaluation of prototypical designs from the perspective of predicting human error. The paper presents the method applied to representative examples. The methodology is considered in terms of the various validation studies that have been conducted, and is discussed in the light of a specific case study
Recombination events among virulence genes in malaria parasites are associated with G-quadruplex-forming DNA motifs
Background Malaria parasites of the genus Plasmodium possess large hyper-variable families of antigen-encoding genes. These are often variantly-expressed and are major virulence factors for immune evasion and the maintenance of chronic infections. Recombination and diversification of these gene families occurs readily, and may be promoted by G-quadruplex (G4) DNA motifs within and close to the variant genes. G4s have been shown to cause replication fork stalling, DNA breakage and recombination in model systems, but these motifs remain largely unstudied in Plasmodium. Results We examined the nature and distribution of putative G4-forming sequences in multiple Plasmodium genomes, finding that their co-distribution with variant gene families is conserved across different Plasmodium species that have different types of variant gene families. In P. falciparum, where a large set of recombination events that occurred over time in cultured parasites has been mapped, we found a strong spatial association between these recombination events and putative G4-forming sequences. Finally, we searched Plasmodium genomes for the three classes of helicase that can unwind G4s: Plasmodium spp. have no identifiable homologue of the highly efficient G4 helicase PIF1, but they do encode two putative RecQ helicases and one homologue of the RAD3-family helicase FANCJ. Conclusions Our analyses, conducted at the whole-genome level in multiple species of Plasmodium, support the concept that G4s are likely to be involved in recombination and diversification of antigen-encoding gene families in this important protozoan pathogen
Fully automated segmentation and tracking of the intima media thickness in ultrasound video sequences of the common carotid artery
Abstract—The robust identification and measurement of the intima media thickness (IMT) has a high clinical relevance because it represents one of the most precise predictors used in the assessment of potential future cardiovascular events. To facilitate the analysis of arterial wall thickening in serial clinical investigations, in this paper we have developed a novel fully automatic algorithm for the segmentation, measurement, and tracking of the intima media complex (IMC) in B-mode ultrasound video sequences. The proposed algorithm entails a two-stage image analysis process that initially addresses the segmentation of the IMC in the first frame of the ultrasound video sequence using a model-based approach; in the second step, a novel customized tracking procedure is applied to robustly detect the IMC in the subsequent frames. For the video tracking procedure, we introduce a spatially coherent algorithm called adaptive normalized correlation that prevents the tracking process from converging to wrong arterial interfaces. This represents the main contribution of this paper and was developed to deal with inconsistencies in the appearance of the IMC over the cardiac cycle. The quantitative evaluation has been carried out on 40 ultrasound video sequences of the common carotid artery (CCA) by comparing the results returned by the developed algorithm with respect to ground truth data that has been manually annotated by clinical experts. The measured IMTmean ± standard deviation recorded by the proposed algorithm is 0.60 mm ± 0.10, with a mean coefficient of variation (CV) of 2.05%, whereas the corresponding result obtained for the manually annotated ground truth data is 0.60 mm ± 0.11 with a mean CV equal to 5.60%. The numerical results reported in this paper indicate that the proposed algorithm is able to correctly segment and track the IMC in ultrasound CCA video sequences, and we were encouraged by the stability of our technique when applied to data captured under different imaging conditions. Future clinical studies will focus on the evaluation of patients that are affected by advanced cardiovascular conditions such as focal thickening and arterial plaques
Resonance-like piezoelectric electron-phonon interaction in layered structures
We show that mismatch of the piezoelectric parameters between layers of
multiple-quantum well structures leads to modification of the electron-phonon
interaction. In particular, short-wavelength phonons propagating perpendicular
to the layers with wavevector close to , where is the period of
the structure, induce a strong smoothly-varying component of the
piezo-potential. As a result, they interact efficiently with 2D electrons. It
is shown, that this property leads to emission of collimated
quasi-monochromatic beams of high-frequency acoustic phonons from hot electrons
in multiple-quantum well structures. We argue that this effect is responsible
for the recently reported monochromatic transverse phonon emission from
optically excited GaAs/AlAs superlattices, and provide additional experimental
evidences of this.Comment: 6 pages, 7 figure
A field study of team working in a new human supervisory control system
This paper presents a case study of an investigation into team behaviour in an energy distribution company. The main aim was to investigate the impact of major changes in the company on system performance, comprising human and technical elements. A socio-technical systems approach was adopted. There were main differences between the teams investigated in the study: the time of year each control room was studied (i.e. summer or winter),the stage of development each team was in (i.e. 10 months), and the team structure (i.e. hierarchical or heterarchical). In all other respects the control rooms were the same: employing the same technology and within the same organization. The main findings were: the teams studied in the winter months were engaged in more `planning’ and `awareness’ type of activities than those studies in the summer months. Newer teams seem to be engaged in more sharing of information than older teams, which maybe indicative of the development process. One of the hierarchical teams was engaged in more `system-driven’ activities than the heterarchical team studied at the same time of year. Finally, in general, the heterarchical team perceived a greater degree of team working culture than its hierarchical counterparts. This applied research project confirms findings from laboratory research and emphasizes the importance of involving ergonomics in the design of team working in human supervisory control
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