A taxonomic study in the genus Hackelia in western North America

A biosystematic study was made on the species of Hackelia of northwest America and adjacent Canada. During the course of the study 140 populations, representing all species and varieties, were transplanted to the greenhouse for study under controlled conditions. Chromosome counts were made for all 14 taxa studied, and intra- and interspecific hybridizations were attempted. For the study over 3000 specimens were borrowed from 21 herbaria in the United States and Canada. Only two chromosome levels were found: 2n=24 and 2n=48. Chromosome counts were obtained only from mitotic cell divisions, as some difficulty was encountered in making usable pollen-mother cell smears. This was especially true in the tetraploids, where normal chemical techniques for fixation of buds resulted in the chromosomes tending to stick together. Because none of the species have chromosome numbers higher than tetraploid, it was felt that polyploidy, although present, has not been a dominant evolutionary mechanism in this section of the genus. The tetraploid taxa under study probably evolved from one or two original tetraploid ancestors which underwent speciation during the Quaternary period. It was found that nutlet features were of limited value as taxonomic characters in some species of Hackelia. The nutlets of some species are highly variable with regard to surface texture, number and size of intramarginal prickles, and the length and degree of fusion of the marginal prickles, The features of the fornix of the corolla are also variable and must be used with care. The distinctness of the tetraploid taxa is maintained in part by their specific habitat requirements. They occur principally in open sites with rocky to sandy soil, where plant competition is minimal. An artificial key to the species and varieties is presented in the taxonomy section, together with complete synonymies, descriptions, lists of cited specimens, and maps of distribution. One new species is described from southeastern Oregon (Hackelia ophiobia) and one new variety from central Washington (H. hispida var. disjuncta), Hackelia diffusa (Lehm.) Johnst. is defined to include var. diffusa, var.arida (=H. arida (Piper) Johnst.) and var. cottonii (=H. cottonii (Piper) Brand)

Histopathologic and Biochemical Responses in Arctic Marine Bivalve Molluscs Exposed to Experimentally Spilled Oil

Following two experimental spills of chemically dispersed and undispersed crude oil in shallow bays on the northwest coast of Baffin Island, Canadian Arctic, the bivalve molluscs Mya truncata and Macoma calcarea accumulated significant amounts of petroleum hydrocarbons in bays receiving dispersed oil and in those receiving crude oil alone (Boehm et all., 1987). Following the spills, Mya released accumulated hydrocarbons more rapidly than Macoma. ... The results of the biochemical analyses indicate that Mya from the four bays were not severely stressed by either dispersed oil or oil alone. Immediately after the spill, clams from the dispersal oil bays were nearly normal, while those from the bay receiving oil alone appeared stressed. These results seem to corroborate results from analytical chemistry and histopathology: that the acute effects of dispersed oil are greater than those of undispersed oil, but effects of undispersed oil on infaunal molluscs develop more slowly and persist longer than those from dispersed oil.Key words: oil spill, dispersant, Mya truncata, Macoma calcarea, histopathology, biochemistry, neoplasia, free amino acids, glycogen, parasitesMots clés: marée noire, agent de dispersion, Mya truncata, Macoma calcarea, histopathologie, biochimie, néoplasme, acides aminés libres, glycogène, parasite

Information Services for Agriculture: The Role of Technology

Significant improvements in technology-supported information services have created opportunities for their utilization by the farmers and ranchers of our Nation. This report highlights the development and expanded offering of these systems, describes current operational and experimental systems, and presents salient legislative initiatives which address this priority area

Metabolic Feedback Inhibition Influences Metabolite Secretion by the Human Gut Symbiont Bacteroides thetaiotaomicron

Microbial metabolism and trophic interactions between microbes give rise to complex multispecies communities in microbe-host systems. Bacteroides thetaiotaomicron (B. theta) is a human gut symbiont thought to play an important role in maintaining host health. Untargeted nuclear magnetic resonance metabolomics revealed B. theta secretes specific organic acids and amino acids in defined minimal medium. Physiological concentrations of acetate and formate found in the human intestinal tract were shown to cause dose-dependent changes in secretion of metabolites known to play roles in host nutrition and pathogenesis. While secretion fluxes varied, biomass yield was unchanged, suggesting feedback inhibition does not affect metabolic bioenergetics but instead redirects carbon and energy to CO2 and H2. Flux balance analysis modeling showed increased flux through CO2-producing reactions under glucose-limiting growth conditions. The metabolic dynamics observed for B. theta, a keystone symbiont organism, underscores the need for metabolic modeling to complement genomic predictions of microbial metabolism to infer mechanisms of microbemicrobe and microbe-host interactions

A questionnaire elicitation of surgeons' belief about learning within a surgical trial

PMID: 23145113 [PubMed - indexed for MEDLINE] PMCID: PMC3493499 Free PMC ArticlePeer reviewedPublisher PD

Tick Haller\u27s Organ, a New Paradigm for Arthropod Olfaction: How Ticks Differ from Insects

Ticks are the vector of many human and animal diseases; and host detection is critical to this process. Ticks have a unique sensory structure located exclusively on the 1st pairs of legs; the fore-tarsal Haller\u27s organ, not found in any other animals, presumed to function like the insect antennae in chemosensation but morphologically very different. The mechanism of tick chemoreception is unknown. Utilizing next-generation sequencing and comparative transcriptomics between the 1st and 4th legs (the latter without the Haller\u27s organ), we characterized 1st leg specific and putative Haller\u27s organ specific transcripts from adult American dog ticks, Dermacentor variabilis. The analysis suggested that the Haller\u27s organ is involved in olfaction, not gustation. No known odorant binding proteins like those found in insects, chemosensory lipocalins or typical insect olfactory mechanisms were identified; with the transcriptomic data only supporting a possible olfactory G-protein coupled receptor (GPCR) signal cascade unique to the Haller\u27s organ. Each component of the olfactory GPCR signal cascade was identified and characterized. The expression of GPCR, Gαo and β-arrestin transcripts identified exclusively in the 1st leg transcriptome, and putatively Haller\u27s organ specific, were examined in unfed and blood-fed adult female and male D. variabilis. Blood feeding to repletion in adult females down-regulated the expression of all three chemosensory transcripts in females but not in males; consistent with differences in post-feeding tick behavior between sexes and an expected reduced chemosensory function in females as they leave the host. Data are presented for the first time of the potential hormonal regulation of tick chemosensation; behavioral assays confirmed the role of the Haller\u27s organ in N,N-diethyl-meta-toluamide (DEET) repellency but showed no role for the Haller\u27s organ in host attachment. Further research is needed to understand the potential role of the GPCR cascade in olfaction

Limits on the cosmological abundance of supermassive compact objects from a millilensing search in gamma-ray burst data

A new search for the gravitational lens effects of a significant cosmological density of supermassive compact objects (SCOs) on gamma-ray bursts has yielded a null result. We inspected the timing data of 774 BATSE-triggered GRBs for evidence of millilensing: repeated peaks similar in light-curve shape and spectra. Our null detection leads us to conclude that, in all candidate universes simulated, $\Omega_{SCO} < 0.1$ is favored for $10^5 < M_{SCO}/M_{\odot} < 10^9$, while in some universes and mass ranges the density limits are as much as 10 times lower. Therefore, a cosmologically significant population of SCOs near globular cluster mass neither came out of the primordial universe, nor condensed at recombination.Comment: 14 pages including 3 figures, appeared 2001 January 2

Coherent Signal Amplification in Bistable Nanomechanical Oscillators by Stochastic Resonance

Stochastic resonance is a counter-intuitive concept[1,2], ; the addition of noise to a noisy system induces coherent amplification of its response. First suggested as a mechanism for the cyclic recurrence of ice ages, stochastic resonance has been seen in a wide variety of macroscopic physical systems: bistable ring lasers[3], SQUIDs[4,5], magnetoelastic ribbons[6], and neurophysiological systems such as the receptors in crickets[7] and crayfish[8]. Although it is fundamentally important as a mechanism of coherent signal amplification, stochastic resonance is yet to be observed in nanoscale systems. Here we report the observation of stochastic resonance in bistable nanomechanical silicon oscillators, which can play an important role in the realization of controllable high-speed nanomechanical memory cells. Our nanomechanical systems were excited into a dynamic bistable state and modulated in order to induce controllable switching; the addition of white noise showed a marked amplification of the signal strength. Stochastic resonance in nanomechanical systems paves the way for exploring macroscopic quantum coherence and tunneling, and controlling nanoscale quantum systems for their eventual use as robust quantum logic devices.Comment: 18 pages, 4 figure

Microwave Spectroscopy

Contains research objectives and reports on one research project.Signal Corps Contract DA-36-039-sc-8737

Pemanfaatan Aplikasi Mind Map Sebagai Media Inovatif Dalam Pembelajaran Mata Kuliah Pengembangan Pendidikan Kewarganegaraan Sekolah Dasar

This study was conducted to develop an innovative medium in learning Elementary School-Civic Education (PKn SD) Development course in order to improve the lecturer competency in developing good learning media, improving learning quality, and producing a computer and internet-based media product. The development of innovative media in this study was carried out by utilizing mind map application available in internet. This study was taken place in Elementary School Teacher Education, Pedagogic Faculty, Semarang State University. The subject of research consisted of corresponding students and lecturers. This study was an educational research with research and development approach. The procedure of research included preliminary study with descriptive qualitative approach, media development design, design validation and design improvement, and followed with limited trial on media design by applying experimental method (before-after), and product revision, if any, and final product development. The result achieved in this study was that the author had conducted a preliminary study by mapping competency and indicator into PKn SD Development course and then designed the lecturing learning plan as needed by utilizing the mind map application as learning media. The author had designed an innovative media using mind map application and had the media design validated by the competent validators in their area. The mind map application-based learning media had been tried out in treatment class. The result of test with the data processed by the author showed the following result. 1) The result of pretest and posttest showed significant improvement; it could be seen from the number of correct answer minimally 5 (40%) and maximally 13 (63%) in pre-test result and minimally 16 (80%) and maximally 20 (100%) in posttest result. 2) The result of content quality and objective aspect questionnaire before and after using mind map application showed the ratio of 55%: 89%, with instructional quality aspect of 54% : 88%, and technical quality aspect of 51% : 90%, so that the overall ratio was 54% : 89%. Considering the result of data analysis, it could be found that the mind map application use can be developed further as an innovative learning media utilizing computer technology and informatics technology mastery support. The author organized the result of study into a scientific article to be published and organized a final report as accountability