166 research outputs found
Genetic and Cytological Studies on the Affinis Group of Drosophila
No full textIntroduction
The genetic evidence available at present indicates that certain groups of genes tend to remain linked in the various members of the genus Drosophila (Donald 1936; Sturtevant and Tan, 1937; Sturtevant, 1938a, 1940; Sturtevant and Novitaki., 1941). These elements are comparable to the arms of the chromosomes of melanogaster and have accordingly been lettered A, B, C, D, E, and F for X, IIL, IIR, IIIL, IIIR, and IV, respectively. In view of the extensive cytological studies on the various members of the affinis group (Dobzhansky and Socolov, 1939; Miller, 1939; Novitski, unpublished; Sturtevant, unpublished), it has seemed pertinent to extend the homologies with the elements to the salivary gland chromosomes of this group. The high degree of similarity of the salivary gland chromosome arms of the various affinis group species examined renders it possible to make such a correlation within one species, in this case affinis, with the reasonable certainty that the results obtained will apply to other members of the group (athabasca, algonquin, and azteca).
Sturtevant (1939) has homologized a number of mutant genes in affinis with those of melanogaster and pseudoobseura, applying to the linkage groups of affinis the same designations as those of their homologs in pseudoobsoura. In terms of the above mentioned elements, consequently, the affinis linkage groups, XL, XR, II, III, IV, and V correspond to A, D, E, C, B, and F. respectively. Miller (1939), in a study of the salivary gland chromosomes of algonquin, has arbitrarily lettered the units found therein: a two-armed X-chromosome (XL and XS), a single armed autosome (A), two two-armed autosomes (B and C), and a microchromosome (D). In order to avoid confusion, the symbols to be used until the complete correlation has been established will be those of Sturtevant for the linkage groups and those of Miller for the salivary gland chromosomes.
The metaphase chromosomes of males of the affinis group include a V-shaped X-chromosome, a J-shaped Y-chromosome, two pairs of J-shaped autosomes, a pair of rods and a pair of dots (Metz, 1916; Sturtevant and Dobzhansky, 1936; Dobzhansky and Socolov, 1939; Miller, 1939). It seems clear that there is a correspondence between the number of large chromosome arms in the metaphase plate and the euchromatic arms In the salivary gland nucleus (Miller, 1939, for algonquin; Sturtevant, unpublished, for afinis; Novitski, unpublished, for athabasca; Novitski, in Sturtevant, 1940, for azteca.</p
Magnetic and mechanical analysis of Bi-2212 Rutherford cable in a cos-theta sub-scale dipole coil*
No full textFEM Analysis of Hybrid LTS/HTS Cos-theta Dipole Magnet with Heterogeneous Cable Model
No full textThe Lawrence Berkeley National Laboratory (LBNL) and the National High Magnetic Field Laboratory (NHMFL) have published results on Bi-2212 superconductive magnets realized and tested in the canted cosine-theta and solenoid designs, respectively. Fermilab is now preparing for the assembly of the first Bi-2212 stress-managed cosine-theta insert magnet. The insert will be part of the first hybrid cosine-theta magnet made of Nb3Sn outer layers within the US-MDP effort to reach a 20 T bore field. This paper presents the analytical analysis of the cosine-theta Nb3 Sn/Bi-2212 hybrid magnet. We report the parameters, logic, and implementation method of the 2D electromagnetic and mechanical FEM analysis of the LTS/HTS hybrid magnet. Results from a detailed heterogeneous model are compared to the homogeneous model implemented in the past. A Python code has been developed to simulate the current degradation due to stresses in the detail-modeled conductor areas. The current degradation has been introduced in the simulation dynamics for the HTS conductor as an iteration process, updating the input load of Lorentz forces of the energization at each step. The magnetic and mechanical analysis results of the 2D cosine-theta LTS/HTS dipole magnet have been described and analyzed
Simulation und Modellierung im Management und Controlling von Containerhäfen
No full textS.600-604The paper summarizes results obtained within the project "Application of Modern Concepts in the Automated Information Management in Harbours by using advanced IT-solutions" (AMCAI). The COPERNICUS 1994 Programme of the European Commission funds the project AMCAI running from 1995 to 1997. The goal of AMCAI was to create an international network of scientists and experts who would co-ordinate research activities aimed at improving the logistic system of the Riga Harbour Container Terminal (RHCT). This paper logically continues the author's previous paper presented at 8th European Simulation Symposium (Novitski et al. 1996
Design and fabrication of a single-aperture 11 T Nb 3Sn dipole model for LHC upgrades
No full textThe planned upgrade of the LHC collimation system includes additional collimators to be installed in the dispersion suppressor areas of points 2, 3 and 7. To provide the necessary longitudinal space for the collimators, a replacement of 8.33 T Nb-Ti LHC main dipoles with 11 T dipoles based on Nb 3Sn superconductor compatible with the LHC lattice and main systems is being considered. To demonstrate this possibility FNAL and CERN have started a joint program to develop a 2 m long single-aperture dipole magnet with the nominal field of 11 T at ∼11.85 kA current and 60 mm bore. This paper describes the demonstrator magnet magnetic and mechanical designs and analysis, coil fabrication procedure. The Nb 3Sn strand and cable parameters and test results are also reported
Design of 11 T Twin-Aperture NbSn Dipole Demonstrator Magnet for LHC Upgrades
No full textThe LHC collimation upgrade foresees two additional collimators installed in the dispersion suppressor regions of points 2, 3 and 7. To obtain the necessary longitudinal space for the collimators, a solution based on an 11 T dipole as replacement of the 8.33 T LHC main dipoles is being considered. CERN and FNAL have started a joint development program to demonstrate the feasibility of NbSn technology for this purpose. The program started with the development and test of a 2-m-long single-aperture demonstrator magnet. The goal of the second phase is the design and construction of a series of 2-m-long twin-aperture demonstrator magnets with a nominal field of 11 T at 11.85 kA current. This paper describes the electromagnetic design and gives a forecast of the field quality including saturation of the iron yoke and persistent-current effects in the NbSn coils. The mechanical design concepts based on separate collared coils, assembled in a vertically split iron yoke are also discussed
Quench Performance of a 1 m Long Single-Aperture 11 T NbSn Dipole Model for LHC Upgrades
No full textFNAL and CERN are performing a joint R&D program with the goal to build a 5.5-m long twin-aperture 11 T NbSn dipole prototype suitable for installation in the LHC. An important part of the program is the development and test of a series of short single-aperture and twin-aperture models with a nominal field of 11 T at the LHC nominal current of 11.85 kA and 20% margin. This paper describes design features and test results of a 1 m long single-aperture NbSn dipole model fabricated and tested at FNAL
Quench Protection Study of a Single-Aperture 11 T Nb3Sn Demonstrator Dipole for LHC Upgrades
No full textThe planned upgrade of the Large Hadron Collider (LHC) collimation system will include installation of additional collimators in the dispersion suppressor areas. The longitudinal space for the collimators could be provided by replacing 15-m-long 8.33 T NbTi LHC main dipoles with shorter 11 T Nb 3Sn dipoles compatible with the LHC lattice and main systems. FNAL and CERN have started a joint program with the goal of building a 5.5-m-long twin-aperture Nb3Sn dipole prototype suitable for installation in the LHC. The first step of this program is the development of a 2-m-long single-aperture demonstrator dipole with a nominal field of 11 T at the LHC nominal current of 11.85 kA. This paper summarizes the results of quench protection studies of 11 T dipoles performed using the single-aperture Nb 3Sn demonstrator
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