4,725 research outputs found
Skimmers: Their Development and Use in Coastal Louisiana
The origin, development, and utilization of the skimmer net is reviewed along with other historical shrimp gears used in coastal Louisiana. The skimmer was developed to catch white shrimp, Penaeus setiferus, observed jumping over the cork line (headrope) of trawls being worked in shallow waters. A description of the gear is presented including basic components and various frame designs used by fishermen during its development. The advantages of skimmers over bottom trawls include: multiple use as both trawl and butterfly net (wing net), ease of deployment, increased maneuverability, reduction and greater survivability of bycatch, and ability to cover more area due to increased speed and continuous fishing capability. Disadvantages may include compromising vessel stability when stored upright on the deck, possible damage to water bottoms when improperly rigged, and limitation to a 12-foot (3.6 m) maximum depth due to size restrictions. The growing popularity of the skimmer net is evident by its introduction into North Carolina and inquiries from other southeastern Atlantic and Gulf coast states
On Geography and Institutions as Determinants of Foreign Direct Investment. A cross country comparative analysis of sub-Saharan African relative to developing countries
This work explores what factors determine foreign direct investment (FDI) in sub-Sahara Africa (SSA) relative to non-sub-Saharan African countries, using a panel data set which encompasses most of the world´s developing countries between 1997 and 2006. The results indicate that institutions and infrastructure development promoted FDI to non-SSA but did not induce FDI to sub-Saharan Africa. Geography played a modest and indirect role. The marginal benefit from openness to trade was higher for SSA, which is closely related to resource-seeking FDI that did not translate into sustained economic growth, neither institutional change, but consequently crowded out the second FDI wave of manufacturing. At the same time, FDI into value-added manufacturing largely located in non-SSA countries acted as engine for scaling the economic development ladder through institutional improvement for a number of non-SSA countries. Hence, FDI has the potential to act as a reliable and equitable driver of sustained economic development and poverty alleviation. The destiny of the “resource curse” linked to FDI failure marks the novelty of this paper in the FDI and development literature.Foreign direct investment, developing countries, sub-Saharan Africa, resource curse, geography, institutions
Lack of superconductivity in the phase diagram of single-crystalline Eu(Fe1-xCox)2As2 grown by transition metal arsenide flux
The interplay of magnetism and superconductivity (SC) has been a focus of
interest in condensed matter physics for decades. EuFe2As2 has been identified
as a potential platform to investigate interactions between structural,
magnetic, electronic effects as well as coexistence of magnetism and SC with
similar transition temperatures. However, there are obvious inconsistencies in
the reported phase diagrams of Eu(Fe1-xCox)2As2 crystals grown by different
methods. For transition metal arsenide (TMA)-flux-grown crystals, even the
existence of SC is open for dispute. Here we re-examine the phase diagram of
single-crystalline Eu(Fe1-xCox)2As2 grown by TMA flux. We found that the
lattice parameter c shrinks linearly with Co doping, almost twice as fast as
that of the tin-flux-grown crystals. With Co doping, the spin-density-wave
(SDW) order of Fe sublattice is quickly suppressed, being detected only up to x
= 0.08. The magnetic ordering temperature of the Eu2+ sublattice (TEu) shows a
systematic evolution with Co doping, first going down and reaching a minimum at
x = 0.08, then increasing continuously up to x = 0.24. Over the whole
composition range investigated, no signature of SC is observed.Comment: 24 pages, 7 figure
NMR Study of the New Magnetic Superconductor CaK(Fe$0.951Ni0.049)4As4: Microscopic Coexistence of Hedgehog Spin-vortex Crystal and Superconductivity
Coexistence of a new-type antiferromagnetic (AFM) state, the so-called
hedgehog spin-vortex crystal (SVC), and superconductivity (SC) is evidenced by
As nuclear magnetic resonance study on single-crystalline
CaK(FeNi)As. The hedgehog SVC order is clearly
demonstrated by the direct observation of the internal magnetic induction along
the axis at the As1 site (close to K) and a zero net internal magnetic
induction at the As2 site (close to Ca) below an AFM ordering temperature
52 K. The nuclear spin-lattice relaxation rate 1/ shows
a distinct decrease below 10 K, providing also unambiguous
evidence for the microscopic coexistence. Furthermore, based on the analysis of
the 1/ data, the hedgehog SVC-type spin correlations are found to be
enhanced below 150 K in the paramagnetic state. These results
indicate the hedgehog SVC-type spin correlations play an important role for the
appearance of SC in the new magnetic superconductor.Comment: 5 pages, 4 figures, accepted for publication in Phys. Rev. B rapid
communicatio
Carbon fibre recycling from milling dust for the application in short fibre reinforced thermoplastics
A new approach to reuse accruing chips and dust from milling operations of carbon reinforced plastics (CFRP) is studied, show-ing how CFRP milling dust, in comparison to primary and pyrolysed fibres, can find application as a filler material in thermo-plastic granulates. Recent examinations show an overall better handling of milling dust when separating it into different classes of fibre lengths reaching up to 600 µm, which typically occur while machining reinforced plastics. Furthermore, the carbon rein-forced polypropylene granulates have improved material properties, e.g. increased rigidity and tensile strength in dependence of their respective filler content towards non-reinforced plastics
Hedgehog Spin-vortex Crystal Antiferromagnetic Quantum Criticality in CaK(Fe1-xNix)4As4 Revealed by NMR
Two ordering states, antiferromagnetism and nematicity, have been observed in
most iron-based superconductors (SCs). In contrast to those SCs, the newly
discovered SC CaK(FeNi)As exhibits an antiferromagnetic
(AFM) state, called hedgehog spin-vortex crystal structure, without nematic
order, providing the opportunity for the investigation into the relationship
between spin fluctuations and SC without any effects of nematic fluctuations.
Our As nuclear magnetic resonance studies on
CaK(FeNi)As (0 0.049) revealed that
CaKFeAs is located close to a hidden hedgehog SVC AFM quantum-critical
point (QCP). The magnetic QCP without nematicity in
CaK(FeNi)As highlights the close connection of spin
fluctuations and superconductivity in iron-based SCs. The advantage of
stoichiometric composition also makes CaKFeAs an ideal platform for
further detailed investigation of the relationship between magnetic QCP and
superconductivity in iron-based SCs without disorder effects.Comment: 6 pages, 5 figures, accepted for publication in Phys. Rev. Let
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