Mutant alleles of the Drosophila decapentaplegic (dpp) gene affect embryonic dorsal-ventral pattern formation, larval viability, and adult cuticle formation from the imaginal disks. The dpp DNA required for this array of functions spans almost 50 kb. We report that the embryonic lethal, ventralizing alleles of the dpp gene are rescued in transgenic animals by an 8-kb fragment of the wild-type dpp DNA. Full rescue, from embryonic lethality to adult viability, is obtained in two situations: in animals hemizygous for the haplolethal dpp gene, and in animals hemizygous for either of two recessive embryonic lethal alleles. In embryos null for dpp, the transformation of dorsal cuticle to ventral cuticle is blocked by one copy of the dpp transposon; two copies permit the hatching of the larvae. The portion of dpp sufficient for these embryonic functions encodes a protein with homology to the transforming growth factor-f3 (
Zonal flow appears in toroidal, magnetically confined plasmas as part of the self-regulated interaction of turbulence and transport processes. For toroidal plasmas having a strong toroidal magnetic field, the zonal flow is predominately poloidally directed. This letter reports the first observation of a zonal flow that is toroidally directed. The measurements are made just inside the last closed flux surface of reversed field pinch plasmas that have a dominant poloidal magnetic field. A limit cycle oscillation between the strength of the zonal flow and the amplitude of plasma potential fluctuations is observed, which provides evidence for self-regulation characteristic of drift-wave-type plasma turbulence. The measurements help advance understanding and gyro-kinetic modeling of toroidal plasmas in the pursuit of fusion energy.
A capacitive probe [Mingsheng, Tan, et al. Rev. Sci. Instrum 88, 023502 (2017)] is one of a few diagnostics that is directly sensitive to the plasma potential. Using this diagnostic technique, a Multi-channel Linear Capacitive Probe (MLCP) is developed for turbulence measurements. The MLCP has 10 spatial channels and provides 9 points of radial electric field measurements simultaneously with a spatial step of 7 mm. A new readout circuit and a correction technique for low frequency attenuation are also developed to achieve the required spatial and time resolution. A performance test of the MLCP using a reversed field pinch plasma confirms that the MLCP resolves sub-centimeter structures of the equilibrium radial electric field profile and fluctuations up to 680 kHz.
Based on technologies developed for the Jet Propulsion Laboratory (JPL) Free-Hying-Magnetometer (PPM) concept,' we propose to modify the present design of FFMs for detection of mines and arsenals with large magnetic signature. The result will be an integrated miniature sensor system capable of identifying local magnetic field anomaly caused by a magnetic dipole moment. Proposed integrated sensor system is in line with the JPL technology road-map for development of autonomous, intelligent, networked, integrated systems with a broad range of applications. In addition, advanced sensitive magnetic sensors (e.g; silicon micromachined magnetometer, laser pumped helium magnetometer) are being developed for future NASA space plasma probes.It is envisioned that a fleet of these Integrated Sensor Systems (ISS) units will be dispersed on a mine-field via an aerial vehicle (a low-flying airplane or a helicopter). The number of such sensor systems in each fleet and the corresponding in-situ probe-grid cell size is based on the slrength of magnetic anomaly of the target and 155 measurement resolution of magnetic field vector. After a specified time, 155 units will transmit the measured magnetic field and attitude data to an air-borne platform for further data processing. The cycle of data acquistion and transmission will be continued until batteries run out. Data analysis will allow a local deformation of the Earth's magnetic field vector by a magnetic dipole moment to be detected.Each 155 unit consists of miniaturized sensitive 3-axis magnetometer, high resolution analog-to-digital converter (ADC), Field Programmable Gate Array (FPGA)-based data subsystem, Li-batteries and power regulation circuitry, memory, S-band transmitter, single-patch antenna, and a sun angle sensor. 155 unit is packaged with non-magnetic components and the electronic design implements low-magnetic signature circuits. Care is undertaken to guarantee no corruption of magnetometer sensitivity as a result of its close proximity with the electronics and packaging materials. Accurate calibration of the magnetometer response in advance will allow removing the effects of unwanted disturbances. Improvements of the magnetometer performance in the areas of the orthogonality, drift, and temperature coefficient of offset and scale factor are requirecL
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