Hasse-Schmidt Derivations and Coefficient Fields in Positive Characteristics

We show how to express any Hasse-Schmidt derivation of an algebra in terms of a finite number of them under natural hypothesis. As an application, we obtain coefficient fields of the completion of a regular local ring of positive characteristic in terms of Hasse-Schmidt derivationsComment: 14 pages; A gap in the statement of Proposition (2.7) has been fixed and the proof of Theorem (3.14) has been adapte

Precision measurement of magnetic characteristics of an article with nullification of external magnetic fields

An apparatus for characterizing the magnetic field of a device under test is discussed. The apparatus is comprised of five separate devices: (1) a device for nullifying the ambient magnetic fields in a test environment area with a constant applied magnetic field; (2) a device for rotating the device under test in the test environment area; (3) a device for sensing the magnetic field (to obtain a profile of the magnetic field) at a sensor location which is along the circumference of rotation; (4) a memory for storing the profiles; and (5) a processor coupled to the memory for characterizing the magnetic field of the device from the magnetic field profiles thus obtained

Ionospheric storms at geophysically-equivalent sites – Part 2: Local time storm patterns for sub-auroral ionospheres

The response of the mid-latitude ionosphere to geomagnetic storms depends upon several pre-storm conditions, the dominant ones being season and local time of the storm commencement (SC). The difference between a site's geographic and geomagnetic latitudes is also of major importance since it governs the blend of processes linked to solar production and magnetospheric input, respectively. Case studies of specific storms using ionospheric data from both hemispheres are inherently dominated by seasonal effects and the various local times versus longitude of the SCs. To explore inter-hemispheric consistency of ionospheric storms, we identify "geophysically-equivalent-sites" as locations where the geographic and geomagnetic latitudes have the same relationship to each other in both hemispheres. At the longitudes of the dipole tilt, the differences between geographic and geomagnetic latitudes are at their extremes, and thus these are optimal locations to see if pre-conditioning and/or storm-time input are the same or differ between the hemispheres. <br><br> In this study, we use ionosonde values of the F2-layer maximum electron density (<I>Nm</I>F2) to study geophysical equivalency at Wallops Island (VA) and Hobart (Tasmania), using statistical summaries of 206 events during solar cycle #20. We form average patterns of Δ<I>Nm</I>F2 (%) versus local time over 7-day storm periods that are constructed in ways that enhance the portrayal of the average characteristic features of the positive and negative phases of ionospheric storms. The results show a consistency between four local time characteristic patterns of storm-induced perturbations, and thus for the average magnitudes and time scales of the processes that cause them in each hemisphere. Subtle differences linked to small departures from pure geophysical equivalency point to a possible presence of hemispheric asymmetries governed by the non-mirror-image of geomagnetic morphology in each hemisphere

Origin Of the enhanced flexoelectricity of relaxor ferroelectrics

We have measured the bending-induced polarization of Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystals with compositions at the relaxor-ferroelectric phase boundary. The crystals display very large flexoelectricity, with flexocoupling coefficients an order of magnitude bigger than the theoretical upper limit set by the theories of Kogan and Tagantsev. This enhancement persists in the paraphrase up to a temperature T* that coincides with the start of elastic softening in the crystals. Analysis of the temperature dependence and cross-correlation between flexoelectric, dielectric and elastic properties indicates that the large bendinginduced polarization of relaxor ferroelectrics is not caused by intrinsically giant flexoelectricity, but by the reorientation of polar nanotwins that become ferroelastically active below T*

The human-alloprimate interface in Gandoca, Costa Rica: an ethnoprimatological approach to assess conflict between residents and three Neotropical primates

Crop-raiding by nonhuman primates is one of the most common of human-alloprimate interactions, often translating into conflict and reduced tolerance. Although it has not been reported to be as problematic in the Neotropics, examining this interaction is important for identifying potential conflicts and incorporating adequate management practices. In the community of Gandoca, Costa Rica, residents coexist with three sympatric primates: Alouatta palliata, Cebus imitator, and Ateles geoffroyi ornatus. We examined the attitudes and perceptions of 24 individuals towards alloprimates and how crop-raiding influenced them. We evaluated the intensity of such conflict as perceived by the community through semi-structured interviews. Although 75% of the respondents said that crop-raiding was not problematic, 23 animals were identified to raid crops and/or gardens. The three nonhuman primates were reported to raid gardens and crops, but Alouatta more so than Cebus and Ateles. Interestingly, they were all described as “wasteful” when feeding, and this behavior seemed to “bother” people more than the raiding itself. Moreover, Alouatta was more likely to be described negatively, Cebus more neutrally, and Ateles more positively. In conclusion, raiding behaviors affect the residents’ attitudes and perceptions, but other behaviors and physical traits may also factor into people’s perceptions of monkeys

Advanced Communication Technology Satellite (ACTS) multibeam antenna analysis and experiment

One of the most important aspects of a satellite communication system design is the accurate estimation of antenna performance degradation. Pointing error, end coverage gain, peak gain degradation, etc. are the main concerns. The thermal or dynamic distortions of a reflector antenna structural system can affect the far-field antenna power distribution in a least four ways. (1) The antenna gain is reduced; (2) the main lobe of the antenna can be mispointed thus shifting the destination of the delivered power away from the desired locations; (3) the main lobe of the antenna pattern can be broadened, thus spreading the RF power over a larger area than desired; and (4) the antenna pattern sidelobes can increase, thus increasing the chances of interference among adjacent beams of multiple beam antenna system or with antenna beams of other satellites. The in-house developed NASA Lewis Research Center thermal/structural/RF analysis program was designed to accurately simulate the ACTS in-orbit thermal environment and predict the RF antenna performance. The program combines well establish computer programs (TRASYS, SINDA and NASTAN) with a dual reflector-physical optics RF analysis program. The ACTS multibeam antenna configuration is analyzed and several thermal cases are presented and compared with measurements (pre-flight)

Effects of morphology on phonons of nanoscopic silver grains

The morphology of nanoscopic Ag grains significantly affects the phonons. Atomistic simulations show that realistic nanograin models display complex vibrational properties. (1) Single-crystalline grains. Nearly-pure torsional and radial phonons appear at low frequencies. For low-energy, faceted models, the breathing mode and acoustic gap (lowest frequency) are about 10% lower than predicted by elasticity theory (ET) for a continuum sphere of the same volume. The sharp edges and the atomic lattice split the ET-acoustic-gap quintet into a doublet and triplet. The surface protrusions associated with nearly spherical, high-energy models produce a smaller acoustic gap and a higher vibrational density of states (DOS) at frequencies \nu<2 THz. (2) Twined icosahedra. In contrast to the single-crystal case, the inherent strain produce a larger acoustic gap, while the core atoms yield a DOS tail extending beyond the highest frequency of single-crystalline grains. (3) Mark's decahedra, in contrast to (1) and (2), do not have a breathing mode; although twined and strained, do not exhibit a high-frequency tail in the DOS. (4) Irregular nanograins. Grain boundaries and surface disorder yield non-degenerate phonon frequencies, and significantly smaller acoustic gap. Only these nanograins exhibit a low-frequency \nu^2 DOS in the interval 1-2 THz.Comment: Version published in Phys. Rev.

Impact of global warming on ENSO phase change

We compare the physical mechanisms involved in the generation and decay of ENSO events in a control (present day conditions) and Scenario (Is92a, IPCC 1996) simulations performed with the coupled ocean-atmosphere GCM ECHAM4-OPYC3. A clustering technique which objectively discriminates common features in the evolution of the Tropical Pacific Heat Content anomalies leading to the peak of ENSO events allows us to group into a few classes the ENSO events occurring in 240 years of data in the control and scenario runs. In both simulations, the composites of the groups show differences in the generation and development of ENSO. We present the changes in the statistics of the groups and explore the possible mechanisms involved

Printed circuit board coil design with reduced series resistance for high power inductive wireless power transmission systems

Due to the growing use of the popular wireless power transmission (WPT) technology, an innovative method of coil design and optimization is presented in this paper. This method has been applied to develop spiral printed circuit board (PCB) coils with litz-wire structure. From the geometry definition, the design process is carried out by means of finite element analysis (FEA). In addition, as a complement to the design process, some prototypes of spiral PCB coils were built to contrast the simulation results and experimental measurements by means of the small-signal characterization, which reflects the success of the applied method