Assessment of Land Use and Neotropical Herpetofauna Along Steep Gradients of Elevation in an Ecuadorian Ramsar Wetland Site #1143

Using a comparative ecological approach, over the course of 18 days at the transition from a particularly wet to dry season in 2010, I assessed herpetofaunal assemblages and related abiotic parameters (i.e., photosynthetically active radiation, specific conductance, temperature and coarse woody debris) between contiguous forest and human impacted areas along three paired transects across the steep elevation gradient at Laguna de Cube, Ramsar site # 1143. Visual encounter surveys were used to capture herpetofauna with species being processed (e.g., weight, digit length, photographed) and identified to the lowest taxonomic level possible. After evaluating transect data for pooling (i.e., no significant difference in abiotic parameters relative to elevation or land cover, hypotheses were evaluated statistically using Chi Square and Kruskal Wallis, and adjusted for multiple comparisons, with an a priori alpha; 0.10. I depart from convention due to the rarity of the region and accelerating human impacts. A total of 37 species (22 amphibians and 15 reptiles) were captured over 144 hours of direct sampling representative of day and night (n=4), 28 of which are newly described for Laguna de Cube, with three that have IUCN status of near threatened or endangered . As hypothesized, species richness and diversity were significantly greater in the forest than in impacted habitats [i.e., 30 forested versus 21 impacted species; Chi2;2 (2, N = 68) = 46.267, p = 8.9809E-11]. Similarly, abiotic conditions differed significantly by land cover with human impact exceeding forest analogs in 8 of 13 parameters (e.g., PAR; TopF v. TopI= , H = 27.6 df = 5, p = 0.005075) , while forests had significantly greater coarse woody debris [i.e., CWDF = 150,731.97 kg/ha v. CWDI = 47,819.97 kg/ha; Chi2;2 (1, N = 198,550.97) = 135.26, p = 2.897E-31]. Of the species collected several may serve as indicators of biotic integrity with H. pellucens serving as an indicator of degraded human modified land cover occurring in all of the 3 human impact transects and occurring at all elevations. Additionally, I observed morphological anomalies possibly indicative of anthropogenic habitat pollutants, with a majority of these species occurring in impacted environments routinely sprayed with pesticides. Conversely, several species may serve as indicators of native habitat affinity including E. boulengeri and H. fallaciosus both of which are described as forest obligates with risk of extirpation due to forest conversion. It should be noted that four species are not yet identified. When compared to similar herpetofaunal studies (n=6), my richness and diversity estimates meet or exceed those in the primary literature in five of the six comparisons

L-1011 testing with relaxed static stability

Wind tunnel and flight tests indicate that fuel savings of 2 percent can be achieved by center of gravity (C.G.) management for an L-1011 with the current wing configuration. The normal c.b. location is at 25 percent mean aerodynamic center (MAC). The maximum fuel saving occurs for a C.G. location of 35 percent MAC. However, flight at 35 percent requires that the C.G. range be extended aft of the 35-percent point. Flight at C.G. locations aft or 35 percent requires a pitch active control system (PACS) so that handling qualities are not significantly degraded. The development of this PACS is discussed

Relevance of basic laboratory and clinical research activities as part of the vascular surgery fellowship: An assessment by program directors and postfellowship surgeons

AbstractIntroduction: Decreased federal monies for graduate medical education, increased clinical training demands, and a decreased pool of general surgery trainees applying to vascular surgery fellowships have brought into question the relevance of the fellowship research experience. This study sought to describe the recent laboratory experience of the fellows, the value of this experience to program directors (PDs) and the trainees, and what factors related to this experience contributed to the trainee entering an academic career versus a private practice career. Methods: A survey regarding the relevance of research experience during fellowship training was mailed in 2001 to all Accreditation Council for Graduate Medical Education-approved vascular surgery fellowship PDs and vascular surgery fellows (VSFs) from 1988 to 2000 applying for the American Board of Surgery Certificate of Added Qualification in General Vascular Surgery. Results: Survey responses were received from 89% of the PDs (74/83) and 69% of the VSFs (259/378). Among the PDs, 70% had completed an approved fellowship, and current bench research was performed by 46%. The PDs afforded protected research time to 69% of the VSFs (with a mean duration of 12 months). This research was in the basic science laboratory 34% of the time. Only 42% of the PDs considered basic laboratory research to be an important part of the fellowship, whereas 99% believed that clinical research was important. Among the PDs, 42% believed that more practice-oriented fellowships with no basic research were needed, whereas 35% believed that basic research should remain an integral component of the fellowship. VSF basic science productivity was significantly greater from those programs that offered protected research time as compared with those that did not (mean basic science paper published, 1.7 ± 0.1 versus 0.3 ± 0.6 per VSF; P < .001). At the time of the survey, 99 VSFs had entered academic careers and 136 were in private practice. Basic science research had been undertaken by 56% of the VSFs during medical school and by 53% during general surgery residency. Research during the fellowship was performed by 65% of the VSFs. This experience was considered helpful in choosing an academic or private practice career by 44% of the VSFs. A greater proportion of academic surgeons had research experience as VSFs when compared with VSFs who became private practitioners (71% versus 57%; P < .05). VSFs who entered academic careers had a more productive publication record in fellowship than did those who chose private practice (mean paper, 2.4 versus 1.5; P < .05). Overall, 78% of the VSFs believed that their research experience was maturing beyond the technical skills learned. Conclusion: This report provides a benchmark of the vascular surgery fellowship research experience. Most VSFs considered the research experience as it now exists to be worthwhile, and less than half of the PDs believed that it should remain as it is. Research experience in fellowship seemed more influential than that in medical school or general surgical residency in promoting an academic career. (J Vasc Surg 2002;36:1083-91.

Electrode thickness measurement of a Si(Li) detector for the SIXA array

Cathode electrodes of the Si(Li) detector elements of the SIXA X-ray spectrometer array are formed by gold-palladium alloy contact layers. The equivalent thickness of gold in one element was measured by observing the characteristic L-shell X-rays of gold excited by monochromatised synchrotron radiation with photon energies above the L3 absorption edge of gold. The results obtained at 4 different photon energies below the L2 edge yield an average value of 22.4(35) nm which is consistent with the earlier result extracted from detection efficiency measurements. PACS: 29.40.Wk; 85.30.De; 07.85.Nc; 95.55.Ka Keywords: Si(Li) detectors, X-ray spectrometers, X-ray fluorescence, detector calibration, gold electrodes, synchrotron radiationComment: 10 pages, 4 PostScript figures, uses elsart.sty, submitted to Nucl. Instrum. Meth.

Impedance of a Rectangular Beam Tube with Small Corrugations

We consider the impedance of a structure with rectangular, periodic corrugations on two opposing sides of a rectangular beam tube. Using the method of field matching, we find the modes in such a structure. We then limit ourselves to the the case of small corrugations, but where the depth of corrugation is not small compared to the period. For such a structure we generate analytical approximate solutions for the wave number $k$, group velocity $v_g$, and loss factor $\kappa$ for the lowest (the dominant) mode which, when compared with the results of the complete numerical solution, agreed well. We find: if $w\sim a$, where $w$ is the beam pipe width and $a$ is the beam pipe half-height, then one mode dominates the impedance, with $k\sim1/\sqrt{w\delta}$ ($\delta$ is the depth of corrugation), $(1-v_g/c)\sim\delta$, and $\kappa\sim1/(aw)$, which (when replacing $w$ by $a$) is the same scaling as was found for small corrugations in a {\it round} beam pipe. Our results disagree in an important way with a recent paper of Mostacci {\it et al.} [A. Mostacci {\it et al.}, Phys. Rev. ST-AB, {\bf 5}, 044401 (2002)], where, for the rectangular structure, the authors obtained a synchronous mode with the same frequency $k$, but with $\kappa\sim\delta$. Finally, we find that if $w$ is large compared to $a$ then many nearby modes contribute to the impedance, resulting in a wakefield that Landau damps.Comment: 18 pages, 6 figures, 1 bibliography fil

Regulatory function and interdomain communication of group II biotin protein ligases

Biotin is a cofactor required for function of essential biotin dependent enzymes that are involved in metabolic processes including fatty acid biosynthesis, gluconeogenesis, and amino acid catabolism. In order for biotin to act as a cofactor it must first be covalently attached to the biotin dependent enzyme. Biotin protein ligase (BPL) catalyzes this covalent attachment in a two-step reaction. First BPL binds biotin and ATP to synthesize the intermediate biotinoyl-AMP, releasing pyrophosphate. In the second half reaction a conserved lysine residue from the biotin dependent enzyme acts as a nucleophile and attacks the mixed anhydride of biotinoyl-AMP to give the biotinylated protein and release of AMP. Microbial BPLs are classified into two groups. Both group I and group II BPLs have catalytic cores and C-terminal domains that are well conserved between the groups. Group II biotin protein ligases are characterized by the presence of an N-terminal DNA binding domain that functions in transcriptional regulation of the genes of biotin biosynthesis. Escherichia coli BPL, called BirA, is the best-studied example of how an enzyme can also act as a transcriptional regulator of the biotin biosynthetic operon. Transcriptional repression of the E. coli biotin operon occurs when biotin acceptor proteins (biotin dependent enzymes) have been fully biotinylated thereby allowing BirA to accumulate biotinoyl-AMP in its active site. The presence of biotinoyl-AMP results in BirA dimerization and subsequent DNA binding that represses transcription of the biotin biosynthetic operon. Derepression of the biotin operon transcription occurs upon low biotin levels or increased levels of unmodified biotin acceptor proteins. Transfer of accumulated biotinoyl-AMP to acceptor proteins results in monomeric BirA which is unable to bind the biotin operator. The N-terminal DNA binding domain of E. coli BirA is separated from the central domain by a linker region. It was proposed that E. coli BirA could be transformed into a group I BPL by simply removing the N-terminal DNA binding domain, where it would no longer have regulatory activity but would retain ligase activity. However, the E. coli BirA ligase activity was severely compromised when the N-terminal domain was removed, suggesting interdomain communication is required between the DNA binding domain and the central domain for normal ligase activity. The Bacillus subtilis BPL, BirA, is also classified as a Group II BPL based on sequence predictions of an N-terminal helix-turn-helix motif and mutational alteration of its regulatory properties. We report evidence that B. subtilis BirA is a Group II BPL that regulates transcription at three genomic sites: bioWAFDBI, yuiG and yhfUTS. Moreover, unlike the paradigm Group II BPL, E. coli BirA, the N-terminal DNA binding domain can be deleted from Bacillus subtilis BirA without adverse effects on its ligase function. This is the first example of successful conversion of a Group II BPL to a Group I BPL with retention of full ligase activity. The Staphylococcus aureus Group II BPL, BirA, has been reported to bind an imperfect inverted repeat located upstream of the biotin synthesis operon. DNA binding by other Group II BPLs requires dimerization of the protein, which is triggered by synthesis of biotinoyl-AMP (biotinoyl-adenylate), the intermediate in the ligation of biotin to its cognate target proteins. However, the S. aureus BirA was reported to dimerize and bind DNA in the absence of biotin or biotinoyl-AMP (85). These in vitro results argued that the protein would be unable to respond to the levels of biotin or acceptor proteins and thus would lack the regulatory properties of the other characterized BirA proteins. We tested the regulatory function of the S. aureus protein using an in vivo model system and examined its DNA binding properties in vitro using electrophoretic mobility shift and fluorescence anisotropy analyses. We report that the S. aureus BirA is an effective regulator of biotin operon transcription and that the prior data can be attributed to artifacts of mobility shift analyses. We also report that deletion of the DNA binding domain of the S. aureus BirA results in loss of virtually all of its ligation activity