4,299 research outputs found
Artificial reef plan for sport fish enhancement
Hard bottom substrate provides habitat for a multitude of marine fishes, invertebrates, and plants - particularly giant kelp - which are of direct and indirect importance to sport and commercial fisheries. These reefs also enhance
esthetic uses of the marine environment. This document sets forth the plan of the California Department of Fish and Game (CDFG) for the construction of artificial reefs.
The plan includes an outline for defining the purpose of reef construction, gathering information pertinent to reef placement and design, selecting a reef site, preparing a project narrative, obtaining permits and approvals for reef construction, developing a general permit for reef construction, and establishing a system of fisheries habitat enhancement areas. Procedures for constructing and mapping
reefs are discussed and an outline for conducting short- and long-term biological studies of reef communities is presented.
Since 1958, CDFG has constructed 31 reefs off southern California. Thirteen of the largest and most frequently used reefs were mapped using hydroacoustic and radio-locating techniques. Maps of these reefs were published in a 1989 CDFG booklet entitled "A Guide to the Artificial Reefs of Southern California".
Since 1978, seven developmental reefs have been constructed: 1) Pendleton Artificial Reef (1980) - San Diego County;
2) Pitas Point Artificial Reef (1984) Ventura County;
3) Marina Del Rey Artificial Reef (1985) - Los Angeles County; 4)Oceanside Artificial Reef (1987) - San Diego County; 5) Pacific Beach Artificial Reef (1987) - San Diego County; 6) Santa Monica Artificial Reef (1987) - Los
Angeles County; and 7) Topanga Artificial Reef (1987) - Los Angeles County. These reefs were built to improve habitat for sport fishes and associated fauna and to evaluate the enhancement characteristics of reefs related to geographic
location, depth, height, rock size, and reef spacing.
Short-term studies revealed that all reefs have provided shelter, food, nesting, and nursery areas for important fish species and have increased sport fishing opportunities. Furthermore, giant kelp has been observed on all reefs built at suitable depths. More extensive long-term studies are planned in 1998 when reef communities will be at successional equilibrium. These studies will provide
additional information concerning the long-term potential of artificial reefs as habitat for sport fish, invertebrates, and plants.
The plan discusses different types of man-made reefs, including developmental, production, and fishing access reefs, and provides examples of each. It documents
CDFG policy regarding the use of reefs as mitigation for impacts on rocky habitat and kelp. It also documents the laws authorizing CDFG to administer reef construction and studies in California. The activities involved in designing,
permitting, constructing, and evaluating Pendleton Artificial Reef are provided as an example of the reef building and study process.
A list of reefs is provided to document the location, depth, area, materials, and funding sources for all reefs constructed and/or augmented in California. (85pp.
Development in helicopter tail boom strake applications in the US
The use of a strake or spoiler on a helicopter tail boom to beneficially change helicopter tail boom air loads was suggested in the United States in 1975. The anticipated benefits were a change of tail boom loads to reduce required tail rotor thrust and power and improve directional control. High tail boom air loads experienced by the YAH-64 and described in 1978 led to a wind tunnel investigation of the usefullness of strakes in altering such loads on the AH-64, UH-60, and UH-1 helicopters. The wind tunnel tests of 2-D cross sections of the tail boom of each demonstrated that a strake or strakes would be effective. Several limited test programs with the U.S. Army's OH-58A, AH-64, and UH-60A were conducted which showed the effects of strakes were modest for those helicopters. The most recent flight test program, with a Bell 204B, disclosed that for the 204B the tail boom strake or strakes would provide more than a modest improvement in directional control and reduction in tail rotor power
Report of Pendleton artificial reef studies with recommendations for constructing a kelp reef
(Document pdf contains 64 pages
Going Home: Evacuation-Migration Decisions of Hurricane Katrina Survivors
In the wake of Hurricane Katrina, many evacuees from the Gulf region began the difficult process of deciding whether to rebuild or restart elsewhere. We examine pre-Katrina Gulf residents’ decision to return to the post-disaster Gulf region—which we call the “return migration” decision. We estimate two separate return migration models, first utilizing data from a mail survey of individuals in the affected region and then focusing on self-administered questionnaires of evacuees in Houston. Our results indicate that return migration can be affected by household income; age; education level; employment, marital and home ownership status; but the results depend upon the population under consideration. We find no impact of “connection to place” on the return migration decision. While the impact of income is relatively small, we find that the real wage differential between home and host region influences the likelihood of return. Larger implicit costs, in terms of foregone wages for returning, induce a lower likelihood of return. Exploiting this difference at the individual level, we are able to produce estimates of willingness to pay to return home. Average WTP to return home for a sample of relatively poor households is estimated at 3,954 per year.
Intricate targeting of immunoglobulin somatic hypermutation maximizes the efficiency of affinity maturation
It is believed that immunoglobulin-variable region gene (IgV) somatic hypermutation (SHM) is initiated by activation-induced cytidine deaminase (AID) upon deamination of cytidine to deoxyuracil. Patch-excision repair of these lesions involving error prone DNA polymerases such as polη causes mutations at all base positions. If not repaired, the deaminated nucleotides on the coding and noncoding strands result in C-to-T and G-to-A exchanges, respectively. Herein it is reported that IgV gene evolution has been considerably influenced by the need to accommodate extensive C deaminations and the resulting accumulation of C-to-T and G-to-A exchanges. Although seemingly counterintuitive, the precise placement of C and G nucleotides causes most C-to-T and G-to-A mutations to be silent or conservative. We hypothesize that without intricate positioning of C and G nucleotides the efficiency of affinity maturation would be significantly reduced due to a dominance of replacements caused by C and G transition mutations. The complexity of these evolved biases in codon use are compounded by the precise concomitant hotspot/coldspot targeting of AID activity and Polη errors to maximize SHM in the CDRs and minimize mutations in the FWRs
Team-based Classroom Pedagogy Reframed: The Student Perspective
Postsecondary learning environments often utilize team-based pedagogical practices to challenge and support student learning outcomes. This manuscript presents the findings of a qualitative research study that analyzed the viewpoints and perceptions of group or team-based projects among undergraduate business students. Results identified five pro-team thematic perspectives of team learners’ views including better deliverables, increased ideas, improved learning experiences, reduced workload, and collective security. Responses from students who preferred to work autonomously resulted in three themes centered on self-sufficiency, social loafing, and schedule challenges. Two situational student responses were identified regarding how and why faculty should utilize group and team projects in consideration of individual efficiency and assignment objectives and outcomes conflicts. This study concludes with research-based recommendations for teaching, learning, and further research
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