Consequences of ocean scale hypoxia constrained habitat for tropical pelagic fishes

Large areas of cold hypoxic water occur as distinct strata in the eastern tropical Pacific and Atlantic oceans as a result of high productivity initiated by intense nutrient upwelling. Recent studies show that this stratum restricts the depth distribution of tropical pelagic marlins, sailfish, and tunas in the eastern tropical Pacific by compressing the acceptable physical habitat into a narrow surface layer. This layer extends downward to a variable boundary defined by a shallow thermocline, often at 25 m, above a barrier of cold hypoxic water. The depth distributions of marlin and sailfish monitored with electronic tags and mean dissolved oxygen (DO) and temperature profiles show that this cold hypoxic environment constitutes a lower habitat boundary in the eastern tropical Pacific, but not in the western North Atlantic. where DO is not limiting. However. hypoxia-based habitat compression has not actually been demonstrated in the eastern tropical Atlantic Ocean, despite this region having similar oceanographic features to the eastern tropical Pacific. This paper explores the possibility that habitat compression of tropical pelagic fishes exists in the eastro tropical Atlantic and examines possible consequences of this phenomenon. We used Atlantic-wide catches of yellowfin tuna (Thunnus albacares) as an example why habitat compression off west Africa could eventually affect the total Atlantic stock

Computer programs calculate potential and charge distributions in a plasma

Computer program determines the potential and charge distributions between two electrodes in a plasma. Solutions of the Vlasov equations for plane, cylindrical, and spherical geometries are determined and density distributions are found for each of these configurations over a range of conditions

Shape maps for second order partial differential equations

We analyse the singularity formation of congruences of solutions of systems of second order PDEs via the construction of \emph{shape maps}. The trace of such maps represents a congruence volume whose collapse we study through an appropriate evolution equation, akin to Raychaudhuri's equation. We develop the necessary geometric framework on a suitable jet space in which the shape maps appear naturally associated with certain linear connections. Explicit computations are given, along with a nontrivial example

Study of casing treatment stall margin improvement phenomena

The results of a program of experimental and analytical research in casing treatments over axial compressor rotor blade tips are presented. Circumferential groove, axial-skewed slot, and blade angle slot treatments were tested. These yielded, for reduction in stalling flow and loss in peak efficiency, 5.8% and 0 points, 15.3% and 2.0 points, and 15.0% and 1.2 points, respectively. These values are consistent with other experience. The favorable stalling flow situations correlated well with observations of higher-then-normal surface pressures on the rotor blade pressure surfaces in the tip region, and with increased maximum diffusions on the suction surfaces. Annular wall pressure gradients, especially in the 50-75% chord region, are also increased and blade surface pressure loadings are shifted toward the trailing edge for treated configurations. Rotor blade wakes may be somewhat thinner in the presence of good treatments, particularly under operating conditions close to the baseline stall

Continuous repetition rate tuning with timing window independent self-seeding of a gain-switched Fabry-PÉrot Laser

In this work, we propose a novel self-seeding technique that yields timing window independent operation allowing continuous repetition rate tuning of the self-seeded gain-switched (SSGS) laser. This is achieved by employing a highly linearly chirped fiber Bragg grating (LC FBG) as a wavelength selective element. The reflected gain-switched pulses are dispersed to such an extent, that temporal overlap occurs between them. This overlap creates a pseudo continues wave like signal that is re-injected into the gain-switched laser

Evaluation of range and distortion tolerance for high Mach number transonic fan stages. Task 2: Performance of a 1500-foot-per-second tip speed transonic fan stage with variable geometry inlet guide vanes and stator

A 0.5 hub/tip radius ratio compressor stage consisting of a 1500 ft/sec tip speed rotor, a variable camber inlet guide vane and a variable stagger stator was designed and tested with undistorted inlet flow, flow with tip radial distortion, and flow with 90 degrees, one-per-rev, circumferential distortion. At the design speed and design IGV and stator setting the design stage pressure ratio was achieved at a weight within 1% of the design flow. Analytical results on rotor tip shock structure, deviation angle and part-span shroud losses at different operating conditions are presented. The variable geometry blading enabled efficient operation with adequate stall margin at the design condition and at 70% speed. Closing the inlet guide vanes to 40 degrees changed the speed-versus-weight flow relationship along the stall line and thus provided the flexibility of operation at off-design conditions. Inlet flow distortion caused considerable losses in peak efficiency, efficiency on a constant throttle line through design pressure ratio at design speed, stall pressure ratio, and stall margin at the 0 degrees IGV setting and high rotative speeds. The use of the 40 degrees inlet guide vane setting enabled partial recovery of the stall margin over the standard constant throttle line

Emerging Cold War Ideologies During the Populist Era in Latin America and the US Media Response

This thesis aims to identify the characteristics of populism and how those characteristics directly affected the politics and helped set the stage for later military dictatorships in Latin America. This text aims to look at how military regimes in Latin America placed blame on populist leaders and used their inefficiencies as a justification for taking power and establishing military rule. In many instances in Latin America, populist leader’s time in office was characterized by inflation and concern over foreign investment. The concern over foreign investment and possible foreign takeover of local industries provides the background for another concern, that of outside (mainly communist) influence being introduced into the country. One question this paper looks at is why the Cuban Revolution is seen as the turning point for communism in Latin America when there were anti-communist policies during the Populist era. This paper attempts to look at how the Cuban Revolution was seen as the turning point for Latin American countries in their fight against communists. This paper looks at how the US media responded to populist leaders anti-communist statements and how pre-Cold War ideologies are found in populist era rhetoric. This paper hopes to bridge the threat of communism from the so called populist era, to the Cuban Revolution, and through into the military dictatorships

Wavelength tunable lasers in future optical communication systems

Monolithic tunable lasers (TL) have been an important component in dense wavelength division multiplexed (DWDM) systems mainly because of their ability to reduce inventory costs associated with different part numbers for fixed wavelength distributed feedback (DFB) lasers. Moreover, the use of wavelength agile laser diodes in DWDM networks has gained a lot of interest in recent years, due to emerging new applications such as optical switching and routing, which require fast switching lasers in the nanosecond regime (Coldren et al., 2000). Employment of such lasers as tunable transmitters in wavelength packet switched (WPS) networks is one of the possible applications of these devices. In such systems, the information to be transmitted could be encoded onto a destination dependent wavelength and the routing of traffic could be performed on a packet-by-packet basis. The utilization of TLs in an optical switching and routing environment would put stringent requirements on its performance. This would include increased tuning range, high side mode suppression ratio (SMSR), reduced switching time and excellent wavelength stability. The sampled-grating distributed Bragg reflector (SG DBR) TL proves to be an ideal candidate, due to its large tuning range (40 nm), high output power (10 dBm), high side mode suppression ratio (SMSR > 30 dB) and simplicity of integration

Evaluation of hydrogen fuel in a full-scale afterburner

Combustion efficiency of hydrogen fuel for varying afterburner configuration