480 research outputs found
Anatomy, structure and function: Understanding extremes in fear and anxiety by in vivo imaging techniques
An Evaluation of Conservation Reserve Lands in Relation to Pheasant Production and Survival
The ring-necked pheasant (Phasianus colchicus) is one of the most important upland game species over much of the nation. It is also one of the most difficult to effectively manage for the increasing hunter population. The high value of agricultural lands renders habitat improvement programs by state agencies a financial impossibility except on an extremely localized basis. Therefore, the primary pheasant management tool largely remains hunting season manipulation.
The federal government through various agricultural programs may have an influence upon pheasant habitat. Public Law 540 entitled Agricultural Act of 1956, more commonly referred to as the Soil Bank Act (Congress, 84th, 2d Session 1956, 1957), seemed quite promising in this respect. This act provided for two programs, the Acreage Reserve and the Conservation Reserve. The first was a short term program and of negligible value for pheasants. The second was of longer duration and is the one under which remaining Soil Bank lands are included.
Under the Conservation Reserve, cropland was taken out of production and a sound conservation practice established in an attempt to balance the total production and demand of surplus crops. Farmers signed contracts for periods of three to ten years. The federal government then shared the cost of establishing conservation practices and made annual payments for maintaining them during the contract periods. The Conservation Reserve program has not been extended since 1960. Consequently, all remaining contracts will have expired by the end of 1971.
Relatively little Conservation Reserve land has been put into G practices specifically designed for wildlife. These include such things as wildlife food and cover plantings, development or restoration of shallow water areas, and construction of ponds and wildlife watering facilities. Instead, the bulk of wildlife benefits will have to be derived from the A-2 practice, the establishment of permanent vegetative cover, since this is the one most widely employed. Any appraisal of the Conservation Reserve then is, in actuality, an evaluation of habitat provided by the A-2 practice
Beam Losses and Collimation Considerations for PS2
The high intensity beams with different emittances foreseen to be delivered by the PS2, an upgraded version of the actual CERN Proton Synchrotron, require strict control of beam losses in order to protect the machine components and enable their hands-on maintenance. Beam loss simulations based on dedicated numerical tools are undertaken for a variety of PS2 beams and for different loss mechanisms, along the whole accelerating cycle. In this respect, a first iteration of the collimation system is presented
Collimation Considerations For PS2
A main concern in high intensity rings is the evaluation of uncontrolled losses and their minimization using collimation systems. A two-stage system is foreseen for the PS2. The fundamental design strategy for the collimation design is presented, including machine apertures and collimator materials. The dependence of the collimator system efficiency on the primary scraper length and the impact parameter of the particle is evaluated for different collimator locations. Beam loss maps are finally produced displaying the detailed power load deposited around the ring
4 GeV H- Charge Exchange Injection into the PS2
The proposed PS2 will accelerate protons from 4 to 50 GeV. The required beam intensity and brightness can only be achieved with a multi-turn H- charge exchange injection system, where the small emittance injected beam is used to paint the transverse phase space of the PS2 machine. This paper describes the constraints and conceptual design of the H- injection system and its incorporation into the present PS2 lattice. The requirements for the special injection system elements are described, in particular the injection chicane and painting magnet systems and the change exchange foil. Some key performance aspects are investigated, including the stripping efficiency, expected emittance growth and beam loss arising from the simulated number of multiple foil traversals, together with estimates of foil heating
Gamma Transition Jump for PS2
The PS2, which is proposed as a replacement for the existing ~50-year old PS accelerator, is presently considered to be a normal conducting synchrotron with an injection kinetic energy of 4 GeV and a maximum energy of 50 GeV. One of the possible lattices (FODO option) foresees crossing of transition energy near 10 GeV. Since the phase-slip-factor becomes very small near transition energy, many intensity dependent effects can take place in both longitudinal and transverse planes. The aim of the present paper is on the one hand to scale the gamma transition jump, used since 1973 in the PS, to the projected PS2 and on the other hand based on these results the analysis of the implementation and feasibility of a gamma transition jump scheme in a conventional FODO lattice
PS2 Injection, Extraction and Beam Transfer Concepts
The replacement of CERN's existing 26 GeV Proton Synchrotron (PS) machine with a separated-function synchrotron PS2 has been identified as an important part of the possible future upgrade programme of the CERN accelerator complex. The PS2 will require a number of new beam transfer systems associated with injection, extraction, beam dumping and transfer. The different requirements are briefly presented, together with an overview of the conceptual design of these systems, based on the initial PS2 parameter set. The required equipment sub-system performance is derived and discussed. Possible limitations are analysed and the impact on the overall design and parameter set is discussed
Resonant Third-Integer Extraction from the PS2
For the proposed PS2 accelerator several extraction systems are needed, including a slow third-integer resonant extraction. The requirements are presented together with the conceptual considerations for the sextupole locations and strengths, the separatrices at the extraction elements and the aperture implications for the overall machine. Calculations of the phase space separatrices have been computed with a new code for the physics of slow resonant extraction, which is briefly reviewed. Implications for the extraction equipment design and for the injection-extraction straight section optics are discussed
Fast Injection into the PS2
The conceptual considerations of a fast injection system for protons and ions in the proposed PS2 accelerator are presented. Initial design parameters of the injection septum and kicker systems are derived, taking into account rise and fall times, apertures and machine optics. The requirements for an injection dump used for failures are described. Possible limitations and technical issues are outlined
An analysis of MRI derived cortical complexity in premature-born adults : regional patterns, risk factors, and potential significance
Premature birth bears an increased risk for aberrant brain development concerning its structure and function. Cortical complexity (CC) expresses the fractal dimension of the brain surface and changes during neurodevelopment. We hypothesized that CC is altered after premature birth and associated with long-term cognitive development.
One-hundred-and-one very premature-born adults (gestational age <32 weeks and/or birth weight <1500 ​g) and 111 term-born adults were assessed by structural MRI and cognitive testing at 26 years of age. CC was measured based on MRI by vertex-wise estimation of fractal dimension. Cognitive performance was measured based on Griffiths-Mental-Development-Scale (at 20 months) and Wechsler-Adult-Intelligence-Scales (at 26 years).
In premature-born adults, CC was decreased bilaterally in large lateral temporal and medial parietal clusters. Decreased CC was associated with lower gestational age and birth weight. Furthermore, decreased CC in the medial parietal cortices was linked with reduced full-scale IQ of premature-born adults and mediated the association between cognitive development at 20 months and IQ in adulthood.
Results demonstrate that CC is reduced in very premature-born adults in temporoparietal cortices, mediating the impact of prematurity on impaired cognitive development. These data indicate functionally relevant long-term alterations in the brain’s basic geometry of cortical organization in prematurity
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