2,575 research outputs found
Skylab M518 multipurpose furnace convection analysis
An analysis was performed of the convection which existed on ground tests and during skylab processing of two experiments: vapor growth of IV-VI compounds growth of spherical crystals. A parallel analysis was also performed on Skylab experiment indium antimonide crystals because indium antimonide (InSb) was used and a free surface existed in the tellurium-doped Skylab III sample. In addition, brief analyses were also performed of the microsegregation in germanium experiment because the Skylab crystals indicated turbulent convection effects. Simple dimensional analysis calculations and a more accurate, but complex, convection computer model, were used in the analysis
Sacrificing Conservation for Pesos: An Analysis of Select Marine Fisheries in the Political Environment of Mexico
The decline of most Mexican fisheries has occurred so rapidly that few Mexicans and Americans alike fully appreciate the loss. The major focus of this paper will examine the false impression that Mexico is engaging in marine conservation; in reality, its conservation efforts are responses to after-the-fact actions brought on by world critics and as a vehicle to pacify conservationists. The Mexican government can pass a law but lacks the resources to administer and enforce the law and subsequently manage its fisheries in an effective manner. Rather than survey the state of every fishery found in Mexican waters, this paper will examine only four fisheries because of their unique economic, political and ecologic impact, and how the Mexican government allowed their demise. These fisheries are California gray whale, Pacific manta, sea turtle, and totoaba
Laboratory and field measurements of enantiomeric monoterpene emissions as a function of chemotype, light and temperature
Plants emit significant amounts of monoterpenes into the
earth's atmosphere, where they react rapidly to form a multitude of gas phase
species and particles. Many monoterpenes exist in mirror-image forms or
enantiomers. In this study the enantiomeric monoterpene profile for several
representative plants (<i>Quercus ilex L., Rosmarinus officinalis L.</i>,
and <i>Pinus halepensis Mill.</i>) was investigated as a function of
chemotype, light and temperature both in the laboratory and in the field.
Analysis of enantiomeric monoterpenes from 19 <i>Quercus ilex</i>
individuals from Southern France and Spain revealed four regiospecific
chemotypes (genetically fixed emission patterns). In agreement with previous
work, only <i>Quercus ilex</i> emissions increased strongly with light.
However, for all three plant species no consistent enantiomeric variation was
observed as a function of light, and the enantiomeric ratio of α-pinene was found to vary by less than 20% from 100 and
1000 μmol m<sup>−2</sup> s<sup>−1</sup> PAR (photosynthetically active
radiation). The rate of monoterpene emission increased with temperature from
all three plant species, but little variation in the enantiomeric
distribution of α-pinene was observed with temperature. There was
more enantiomeric variability between individuals of the same species than
could be induced by either light or temperature. Field measurements of
α-pinene enantiomer mixing ratios in the air, taken at a
<i>Quercus ilex</i> forest in Southern France, and several other previously
reported field enantiomeric ratio diel cycle profiles are compared. All show
smoothly varying diel cycles (some positive and some negative) even over
changing wind directions. This is surprising in comparison with variations of
enantiomeric emission patterns shown by individuals of the same species
Proximity effect in ultrathin Pb/Ag multilayers within the Cooper limit
We report on transport and tunneling measurements performed on ultra-thin
Pb/Ag (strong coupled superconductor/normal metal) multilayers evaporated by
quench condensation. The critical temperature and energy gap of the
heterostructures oscillate with addition of each layer, demonstrating the
validity of the Cooper limit model in the case of multilayers. We observe
excellent agreement with a simple theory for samples with layer thickness
larger than 30\AA . Samples with single layers thinner than 30\AA deviate from
the Cooper limit theory. We suggest that this is due to the "inverse proximity
effect" where the normal metal electrons improve screening in the
superconducting ultrathin layer and thus enhance the critical temperature.Comment: 4 pages, 4 figure
Passive Tracking System and Method
System and methods are disclosed for passively determining the location of a moveable transmitter utilizing a pair of phase shifts at a receiver for extracting a direction vector from a receiver to the transmitter. In a preferred embodiment, a phase difference between the transmitter and receiver is extracted utilizing a noncoherent demodulator in the receiver. The receiver includes antenna array with three antenna elements, which preferably are patch antenna elements placed apart by one-half wavelength. Three receiver channels are preferably utilized for simultaneously processing the received signal from each of the three antenna elements. Multipath transmission paths for each of the three receiver channels are indexed so that comparisons of the same multipath component are made for each of the three receiver channels. The phase difference for each received signal is determined by comparing only the magnitudes of received and stored modulation signals to determine a winning modulation symbol
Maser Oscillation in a Whispering-Gallery-Mode Microwave Resonator
We report the first observation of above-threshold maser oscillation in a
whispering-gallery(WG)-mode resonator, whose quasi-transverse-magnetic, 17th
azimuthal-order WG mode, at a frequency of approx. 12.038 GHz, with a loaded Q
of several hundred million, is supported on a cylinder of mono-crystalline
sapphire. An electron spin resonance (ESR) associated with Fe3+ ions, that are
substitutively included within the sapphire at a concentration of a few parts
per billion, coincides in frequency with that of the (considerably narrower) WG
mode. By applying a c.w. `pump' to the resonator at a frequency of approx.
31.34 GHz, with no applied d.c. magnetic field, the WG (`signal') mode is
energized through a three-level maser scheme. Preliminary measurements
demonstrate a frequency stability (Allan deviation) of a few times 1e-14 for
sampling intervals up to 100 s.Comment: REVTeX v.4, 3 pages, with a separate .bbl file and 3 .eps figure
Localization Recall Precision (LRP): A New Performance Metric for Object Detection
Average precision (AP), the area under the recall-precision (RP) curve, is
the standard performance measure for object detection. Despite its wide
acceptance, it has a number of shortcomings, the most important of which are
(i) the inability to distinguish very different RP curves, and (ii) the lack of
directly measuring bounding box localization accuracy. In this paper, we
propose 'Localization Recall Precision (LRP) Error', a new metric which we
specifically designed for object detection. LRP Error is composed of three
components related to localization, false negative (FN) rate and false positive
(FP) rate. Based on LRP, we introduce the 'Optimal LRP', the minimum achievable
LRP error representing the best achievable configuration of the detector in
terms of recall-precision and the tightness of the boxes. In contrast to AP,
which considers precisions over the entire recall domain, Optimal LRP
determines the 'best' confidence score threshold for a class, which balances
the trade-off between localization and recall-precision. In our experiments, we
show that, for state-of-the-art object (SOTA) detectors, Optimal LRP provides
richer and more discriminative information than AP. We also demonstrate that
the best confidence score thresholds vary significantly among classes and
detectors. Moreover, we present LRP results of a simple online video object
detector which uses a SOTA still image object detector and show that the
class-specific optimized thresholds increase the accuracy against the common
approach of using a general threshold for all classes. At
https://github.com/cancam/LRP we provide the source code that can compute LRP
for the PASCAL VOC and MSCOCO datasets. Our source code can easily be adapted
to other datasets as well.Comment: to appear in ECCV 201
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