6,820 research outputs found
Stocking, Enhancement, and Mariculture of Penaeus orientalis and Other Species in Shanghai and Zhejiang Provinces, China
China's marine aquaculture landings provide only 18% of its combined freshwater and amrine capture and culture landings, at a per-capita consumption of only 3.2 kg/yr out of a total of 18.1 kg/yr. We described development and some of the results of long-term mariculture and stocking/enhancement projects that have been underway for up to 20 years in the Hangzhou Bay area. Penaeus orientalis (also referred to as P. chinensis) stocking provided up to 400 t/yr, at a total cost-benefit ratio of up to 8 Yuan of landed shrimp per Yuan invested in shrimp stocking. Over 40 t of Penaeus orientalis were produced commercially in 1993, with proceeds being used to fund mariculture and fisheries research. Large scale edible jellyfish restocking is also underway, while semicommercial culture of abalone, Haliotis diversicolor, has been successful. Technical problems limitig mariculture have been solved successfully for some species
Thermodynamics with density and temperature dependent particle masses and properties of bulk strange quark matter and strangelets
Thermodynamic formulas for investigating systems with density and/or
temperature dependent particle masses are generally derived from the
fundamental derivation equality of thermodynamics. Various problems in the
previous treatments are discussed and modified. Properties of strange quark
matter in bulk and strangelets at both zero and finite temperature are then
calculated based on the new thermodynamic formulas with a new quark mass
scaling, which indicates that low mass strangelets near beta equilibrium are
multi-quark states with an anti-strange quark, such as the pentaquark
(u^2d^2\bar{s}) for baryon nmber 1 and the octaquark (u^4d^3\bar{s}) for
dibaryon etc.Comment: 14 pages, 12 figures, Revtex4 styl
TMBF: Bloom filter algorithms of time-dependent multi bit-strings for incremental set
Set is widely used as a kind of basic data structure. However, when it is used for large scale data set the cost of storage, search and transport is overhead. The bloom filter uses a fixed size bit string to represent elements in a static set, which can reduce storage space and search cost that is a fixed constant. The time-space efficiency is achieved at the cost of a small probability of false positive in membership query. However, for many applications the space savings and locating time constantly outweigh this drawback. Dynamic bloom filter (DBF) can support concisely representation and approximate membership queries of dynamic set instead of static set. It has been proved that DBF not only possess the advantage of standard bloom filter, but also has better features when dealing with dynamic set. This paper proposes a time-dependent multiple bit-strings bloom filter (TMBF) which roots in the DBF and targets on dynamic incremental set. TMBF uses multiple bit-strings in time order to present a dynamic increasing set and uses backward searching to test whether an element is in a set. Based on the system logs from a real P2P file sharing system, the evaluation shows a 20% reduction in searching cost compared to DBF
Coherent population trapping in a dressed two-level atom via a bichromatic field
We show theoretically that by applying a bichromatic electromagnetic field,
the dressed states of a monochromatically driven two-level atom can be pumped
into a coherent superposition termed as dressed-state coherent population
trapping. Such effect can be viewed as a new doorknob to manipulate a two-level
system via its control over dressed-state populations. Application of this
effect in the precision measurement of Rabi frequency, the unexpected
population inversion and lasing without inversion are discussed to demonstrate
such controllability.Comment: 14 pages, 6 figure
Multiwavelength observations of a partially eruptive filament on 2011 September 8
In this paper, we report our multiwavelength observations of a partial
filament eruption event in NOAA active region 11283 on 2011 September 8. A
magnetic null point and the corresponding spine and separatrix surface are
found in the active region. Beneath the null point, a sheared arcade supports
the filament along the highly complex and fragmented polarity inversion line.
After being activated, the sigmoidal filament erupted and split into two parts.
The major part rose at the speeds of 90150 km s before reaching the
maximum apparent height of 115 Mm. Afterwards, it returned to the solar
surface in a bumpy way at the speeds of 2080 km s. The rising and
falling motions were clearly observed in the extreme-ultravoilet (EUV), UV, and
H wavelengths. The failed eruption of the main part was associated with
an M6.7 flare with a single hard X-ray source. The runaway part of the
filament, however, separated from and rotated around the major part for 1
turn at the eastern leg before escaping from the corona, probably along
large-scale open magnetic field lines. The ejection of the runaway part
resulted in a very faint coronal mass ejection (CME) that propagated at an
apparent speed of 214 km s in the outer corona. The filament eruption
also triggered transverse kink-mode oscillation of the adjacent coronal loops
in the same AR. The amplitude and period of the oscillation were 1.6 Mm and 225
s. Our results are important for understanding the mechanisms of partial
filament eruptions and provide new constraints to theoretical models. The
multiwavelength observations also shed light on space weather prediction.Comment: 46 pages, 17 figures, 1 table, accepted for publication in Ap
A new approach to the derivation of dynamic information from ionosonde measurements
International audienceA new approach is developed to derive dynamic information near the peak of the ionospheric F-layer from ionosonde measurements. This approach avoids deducing equivalent winds from the displacement of the observed peak height from a no-wind equilibrium height, so it need not determine the no-wind equilibrium height which may limit the accuracy of the deduced winds, as did the traditional servo theory. This approach is preliminarily validated with comparisons of deduced equivalent winds with the measurements from the Fabry-Perot interferometer, the Millstone Hill incoherent scatter radar and with previous works. Examples of vertical components of equivalent winds (VEWs), over Wuhan (114.4° E, 30.6° N, 45.2° dip), China in December 2000 are derived from Wuhan DGS-256 Digisonde data. The deduced VEWs show large day-to-day variations during the winter, even in low magnetic activity conditions. The diurnal pattern of average VEWs is more complicated than that predicted by the empirical Horizontal Wind Model (HWM). Using an empirical electric field model based on the observations from Jicamarca radar and satellites, we investigate the contributions to VEWs from neutral winds and from electric fields at the F-layer peak. If the electric field model is reasonable for Wuhan during this period, the neutral winds contribute mostly to the VEWs, and the contribution from the E × B drifts is insignificant
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