1,605 research outputs found
Asymptotic Exit Location Distributions in the Stochastic Exit Problem
Consider a two-dimensional continuous-time dynamical system, with an
attracting fixed point . If the deterministic dynamics are perturbed by
white noise (random perturbations) of strength , the system state
will eventually leave the domain of attraction of . We analyse the
case when, as , the exit location on the boundary
is increasingly concentrated near a saddle point of the
deterministic dynamics. We show that the asymptotic form of the exit location
distribution on is generically non-Gaussian and asymmetric,
and classify the possible limiting distributions. A key role is played by a
parameter , equal to the ratio of the stable
and unstable eigenvalues of the linearized deterministic flow at . If
then the exit location distribution is generically asymptotic as
to a Weibull distribution with shape parameter , on the
length scale near . If it is generically
asymptotic to a distribution on the length scale, whose
moments we compute. The asymmetry of the asymptotic exit location distribution
is attributable to the generic presence of a `classically forbidden' region: a
wedge-shaped subset of with as vertex, which is reached from ,
in the limit, only via `bent' (non-smooth) fluctuational paths
that first pass through the vicinity of . We deduce from the presence of
this forbidden region that the classical Eyring formula for the
small- exponential asymptotics of the mean first exit time is
generically inapplicable.Comment: This is a 72-page Postscript file, about 600K in length. Hardcopy
requests to [email protected] or [email protected]
Global Communication and Cross-Cultural Competence: Twenty-First Century Micro-Case Studies
Sensitivity to diversity now demands a strategic understanding of the importance of cross-cultural communication competence in every action in organizations, communities, and nations throughout the world. This article contains seven micro-cases, each of which highlights a discussion of communication and cultural impact. The cases range from issues related to handshakes, communication with powerful people, collaborating in a divergent culture, unintended impact in meetings, and regional pronunciation differences. The cases include discussion questions, references for additional reading, and one unique feature: a âbumper stickerâ summary. The article features a section on Approaching the Challenges. This discusses major communication and cultural theories, which provides a basis for avoiding or reconciling differences. The concluding section, Extending Indirect Experiential Opportunities, advocates specific methods to evolve an individualâs global mind-set and communication capabilities
Report of the NAFO Joint Commission-Scientific Council Working Group on Ecosystem Approach Framework to Fisheries Management (WG-EAFFM) Meeting
1. Opening by the co-Chairs, Robert Day (Canada) and Andrew Kenny (EU)
2. Appointment of Rapporteur
3. Adoption of Agenda
4. SC response to FC requests for advice:
a. Consideration of 2014 SC advice regarding extent of the New England and Corner Rise Seamounts (Annex 13 of FC Doc. 16-20)
b. Risk assessment of scientific surveys impact on VME in closed areas (2016 FC Request to SC #3)
5. Discussion of ongoing matters:
a. Assessment of NAFO bottom fisheries SAI (2016 FC Request to SC # 6)
b. Progress of analysis undertaken by EU NEREIDA funded research project
c. Update on identification and mapping of sensitive species and habitats in the NAFO area
d. Further development and application of the Ecosystems Approach to Fisheries (EAF) Roadmap, including further consideration of any issues raised at the Scientific Council Meeting, 01-15 June 2017
e. Alfonsino fishery on seamounts in the NAFO Regulatory Area.
6. Recommendations to forward to the Commission and Scientific Council
7. Other Matters
a. Presentation: Canadaâs Marine Conservation targets for 2017 and 2020: The Role of Fisheries
b. NAFO Working Group on Improving Efficiency of NAFO Working Group Process
c. Recommendation for a new co-Chair
d. Timely availability of meeting reports
8. Adoption of Report
9. Adjournmen
Effects of Gas Flaring on the Behavior of Night-migrating Birds at an Artificial Oil-production Island, Arctic Alaska
We studied movement rates and the general flight behavior of bird flocks seen on radar and recorded visually at Northstar Island, Arctic Alaska, from 13 to 27 September 2002. Most of this period (13 â 19 and 21 â 27 September) had no gas-flaring events, but a major gas-flaring event occurred on the night of 20 September. Movement rates of targets on radar and of bird flocks recorded visually in the first ~50% â 60% of the night were much lower during the non-flaring period than during the night of flaring, whereas rates in the last ~40% â 50% of the night were similar in all periods. The general flight behavior of birds also differed significantly, with higher percentages of both radar targets and bird flocks exhibiting straight-line (directional) flight behaviors during the non-flaring periods and higher percentages of radar targets and bird flocks exhibiting non-straight-line (erratic and circling) flight behaviors during the gas-flaring period. During the night of gas flaring, the bright illumination appeared to have an effect only after sunset, when flocks of birds circled the island after being drawn in from what appeared to be a substantial distance from the island. On both radar and visual sampling, the number of bird flocks approaching the island declined over the evening, and the attractiveness of the light from flaring appeared to decline. The visibility of the moon appeared to have little effect on the behavior of birds. Because illumination from extensive gas-flaring is such a strong attractant to migrating birds and because most bird flocks fly at low altitudes over the water, flaring booms on coastal and offshore oil-production platforms in Arctic Alaska should be positioned higher than the mean flight altitudes of migrating birds to reduce the chances of incineration.Nous avons Ă©tudiĂ© les taux de dĂ©placement et le comportement de vol gĂ©nĂ©ral des troupeaux dâoiseaux captĂ©s par radar ou consignĂ©s visuellement Ă lâĂźle Northstar, dans lâAlaska de lâArctique, du 13 au 27 septembre 2002. Pendant presque toute cette pĂ©riode (du 13 au 19 et du 21 au 27 septembre), il nây a pas eu de brĂ»lage de gaz Ă la torche, mais la nuit du 20 septembre, il y a eu un important brĂ»lage de gaz Ă la torche. Les taux de dĂ©placement des cibles radar et des troupeaux dâoiseaux consignĂ©s visuellement pendant la premiĂšre tranche dâenviron 50 % Ă 60 % de la nuit Ă©taient beaucoup moins Ă©levĂ©s pendant la pĂ©riode oĂč il nây avait pas de brĂ»lage Ă la torche que pendant la nuit oĂč il y a eu brĂ»lage Ă la torche, tandis que pendant la deuxiĂšme tranche dâenviron 40 % Ă 50 % de la nuit, les taux de dĂ©placement Ă©taient semblables pendant toutes les pĂ©riodes. Le comportement de vol gĂ©nĂ©ral des oiseaux a Ă©galement affichĂ© une diffĂ©rence considĂ©rable. De plus grands pourcentages de cibles radar et de troupeaux dâoiseaux adoptaient un comportement de vol rectiligne (direct) pendant les pĂ©riodes oĂč il nây avait pas de brĂ»lage Ă la torche, et de plus grands pourcentages de cibles radar et de troupeaux dâoiseaux affichaient un comportement de vol non rectiligne (erratique et indirect) pendant la pĂ©riode oĂč il y a eu brĂ»lage Ă la torche. La nuit du brĂ»lage Ă la torche, la vive illumination nâa semblĂ© avoir un effet quâaprĂšs le coucher du soleil, quand les troupeaux dâoiseaux encerclaient lâĂźle aprĂšs avoir Ă©tĂ© attirĂ©s depuis un endroit qui semblait trĂšs lointain. Tant pour lâĂ©chantillonnage prĂ©levĂ© par radar que par consignation visuelle, le nombre de troupeaux dâoiseaux sâapprochant de lâĂźle diminuait dans le courant de la soirĂ©e, et lâattrait de la lumiĂšre Ă©manant du brĂ»lage Ă la torche semblait Ă©galement diminuer. La visibilitĂ© de la lune semblait avoir peu dâeffet sur le comportement des oiseaux. Puisque lâillumination provenant du brĂ»lage prolongĂ© Ă la torche exerce une si grande force dâattraction chez les oiseaux migrateurs, et puisque la plupart des troupeaux dâoiseaux volent en basse altitude au-dessus de lâeau, le torchage effectuĂ© sur les plateformes pĂ©troliĂšres cĂŽtiĂšres et extracĂŽtiĂšres dans lâAlaska de lâArctique devrait ĂȘtre positionnĂ© plus haut que les altitudes moyennes de vol des oiseaux migrateurs afin de rĂ©duire les risques dâincinĂ©ration
Nonenzymatic Glucosylation of Rat Albumin: Studies in Vitro and in Vivo
Incubation of rat serum with D-glucose in vitro resulted in nonenzymatic glucosylation of serum proteins. Analysis of freshly isolated rat albumin by ion exchange chromatography indicated that the glucosylated albumin accounts for 6.7.+-. 0.9% of total albumin in normal rat serum. Glucosylation of rat albumin in vitro was 1st order with respect to glucose and albumin concentrations and occurs primarily (\u3e 90%) at intrachain lysine residues. Kinetic analysis and inhibition of glucosylation by aspirin suggest that 1 reactive lysine residue is the primary site of glucosylation. Less than 5% of the radioactivity from glucosyl-albumin was released as glucose or mannose by hydrolysis conditions normally used for the analysis of neutral sugars in glycoproteins. Studies in vivo demonstrated that the half-life of albumin in normal rats was unaffected by the addition of 1 mol of glucose/mol of albumin. In addition, glucosylation was a stable modification since 125i-albumin isolated up to 3 days after injection of glucosylated 125i-albumin was recovered only in the glucosylated fraction. In contrast, following injection of unglucosylated 125i-albumin there was a gradual shift of 125i radioactivity to the glucosylated albumin fraction, as would be predicted for nonenzymatic glucosylation occurring in the circulation. Finally, levels of glucosylated albumin isolated from diabetic rats (alloxan induced) were significantly (4-fold) elevated 4 days after withdrawal from insulin therapy. The rat should be a suitable animal model for in vivo studies on nonenzymatic glucosylation of albumin and other serum proteins in normal and diabetic metabolic states
Effects of a Hazing-Light System on Migration and Collision Avoidance of Eiders at an Artificial Oil-Production Island, Arctic Alaska
During migration, Common and King Eiders (Somateria mollissima and S. spectabilis) cross the Beaufort and Chukchi Seas of Arctic Alaska. Because they may become attracted to lights, eiders are susceptible to collision with structures, including offshore oil facilities. We used ornithological radar in 2001 â 04 to characterize the behavior of eiders migrating past Northstar Island, an oil-production island near Prudhoe Bay, Alaska, and to assess the effects of a hazing-light system on migrating eiders. âEiderâ radar targets exhibited pulsed, irregular periods of movement; movement rates were higher when sea ice was present, without precipitation, and during tailwinds and crosswinds but were not affected by lights. Velocities (ground speeds) were higher when ice was present and with strong tailwinds. They were lower at night when the lights were on, but higher during the day when the lights were on. Radar targets exhibited little variation in flight behavior as they passed the island; the proportion of non-directional behavior was larger when ice was present, with tailwinds, with weak winds, and near the full moon when it was not visible. Lights had no effect on flight behavior. Birds tended to exhibit more course changes as they approached the island, greater angular changes when they changed course, and larger net increases in passing distance as a result of those course changes when the lights were on; however, none of these differences were statistically significant. Overall, the hazing lights at Northstar did not disrupt the birdsâ migratory movements but resulted in increased avoidance of the island.En pĂ©riode de migration, lâeider Ă duvet et lâeider Ă tĂȘte grise (Somateria mollissima et S. spectabilis) survolent la mer de Beaufort et la mer des Tchouktches dans lâAlaska de lâArctique. Comme ils sont attirĂ©s par les lumiĂšres, les eiders risquent dâentrer en collision avec des structures, y compris les installations pĂ©troliĂšres au large. De 2001 Ă 2004, nous avons utilisĂ© un radar ornithologique pour caractĂ©riser le comportement des eiders qui migrent au-delĂ de lâĂźle Northstar, une Ăźle de production pĂ©troliĂšre prĂšs de Prudhoe Bay, en Alaska, et pour Ă©valuer les effets dâun systĂšme dâĂ©clairage de dispersion sur les eiders en migration. Les « eiders » ciblĂ©s par le radar prĂ©sentaient des pĂ©riodes de mouvement pulsĂ©es et irrĂ©guliĂšres; les taux de mouvement Ă©taient plus importants en prĂ©sence de glace marine, en lâabsence de prĂ©cipitation et en prĂ©sence de vent arriĂšre et de vent latĂ©ral, mais nâĂ©taient pas touchĂ©s par les lumiĂšres. Les vĂ©locitĂ©s (vitesses au sol) Ă©taient plus Ă©levĂ©es en prĂ©sence de glace et de forts vents arriĂšre. Elles Ă©taient plus basses la nuit lorsque les lumiĂšres Ă©taient allumĂ©es, mais plus Ă©levĂ©es le jour lorsque les lumiĂšres Ă©taient allumĂ©es. Nous avons observĂ© peu de variation quant au comportement de vol des cibles atteintes par le radar pendant quâelles survolaient lâĂźle; la proportion de comportements de vol non directionnels Ă©tait plus importante en prĂ©sence de glace, de vent arriĂšre, de vent faible et lorsque la pleine lune nâĂ©tait pas visible. Les lumiĂšres nâont pas eu dâimpact sur le comportement de vol. Lorsque les lumiĂšres Ă©taient allumĂ©es, les oiseaux avaient tendance Ă changer de direction plus souvent durant leur vol Ă lâapproche de lâĂźle et Ă effectuer de plus grandes variations angulaires lorsquâils changeaient de direction, puis prĂ©sentaient une nette augmentation de la distance de passage Ă la suite de ces changements de direction. Toutefois, aucune de ces diffĂ©rences nâĂ©tait statistiquement importante. En gĂ©nĂ©ral, les lumiĂšres de dispersion de lâĂźle Northstar nâont pas nui aux mouvements migratoires des oiseaux, mais ces derniers ont davantage Ă©vitĂ© de voler prĂšs de lâĂźle
Noise-Activated Escape from a Sloshing Potential Well
We treat the noise-activated escape from a one-dimensional potential well of
an overdamped particle, to which a periodic force of fixed frequency is
applied. We determine the boundary layer behavior, and the physically relevant
length scales, near the oscillating well top. We show how stochastic behavior
near the well top generalizes the behavior first determined by Kramers, in the
case without forcing. Both the case when the forcing dies away in the weak
noise limit, and the case when it does not, are examined. We also discuss the
relevance of various scaling regimes to recent optical trap experiments.Comment: 9 pages, no figures, REVTeX, expanded versio
Basolateral Amygdala Modulates Terminal Dopamine Release in the Nucleus Accumbens and Conditioned Responding
BackgroundâDopamine signaling in the nucleus accumbens (NAc) is essential for goal-directed behaviors and primarily arises from burst firing of ventral tegmental area (VTA) neurons. However, the role of associative neural substrates such as the basolateral amygdala (BLA) in regulating phasic dopamine release in the NAc, particularly during reward-seeking, remains unknown. MethodsâMale Sprague-Dawley rats learned to discriminate two cues; a discriminative stimulus (DS) that predicted sucrose reinforcement contingent upon a lever press, and a non-associated stimulus (NS) that predicted a second lever never reinforced with sucrose. Following training, a test session was completed in which NAc dopamine was measured using fast-scan cyclic voltammetry in conjunction with inactivation of the ipsilateral BLA (GABA agonists; baclofen/muscimol) to determine the contribution of BLA activity to dopamine release in the NAc core during the task. ResultsâUnder vehicle conditions, DS and NS presentation elicited dopamine release within the NAc core. The DS evoked significantly more dopamine than the NS. Inactivation of the BLA selectively attenuated the magnitude of DS-evoked dopamine release, concurrent with an attenuation of DS-evoked conditioned approaches. Other behavioral responses (e.g., lever pressing) and dopamine release concomitant with those events were unaltered by BLA inactivation. Furthermore, neither VTA electrically-stimulated dopamine release nor the probability of high concentration dopamine release events was altered following BLA inactivation. ConclusionsâThese results demonstrate that the BLA terminally modulates dopamine signals within the NAc core under specific, behaviorally-relevant conditions, illustrating a functional mechanism by which the BLA selectively facilitates responding to motivationally salient environmental stimuli
Neutral Nickel(II)-Based Catalysts for Ethylene Polymerization
Neutral salicylaldiminato Ni(II) complexes have been synthesized, and their structure has been confirmed by an X-ray analysis of complex 4e. These compounds are active catalysts for the polymerization of ethylene under mild conditions in the presence of a phosphine scavenger such as Ni(COD)_2 or B(C_6F_5)_3
GLIDERS - A web-based search engine for genome-wide linkage disequilibrium between HapMap SNPs
<p>Abstract</p> <p>Background</p> <p>A number of tools for the examination of linkage disequilibrium (LD) patterns between nearby alleles exist, but none are available for quickly and easily investigating LD at longer ranges (>500 kb). We have developed a web-based query tool (GLIDERS: Genome-wide LInkage DisEquilibrium Repository and Search engine) that enables the retrieval of pairwise associations with r<sup>2 </sup>â„ 0.3 across the human genome for any SNP genotyped within HapMap phase 2 and 3, regardless of distance between the markers.</p> <p>Description</p> <p>GLIDERS is an easy to use web tool that only requires the user to enter rs numbers of SNPs they want to retrieve genome-wide LD for (both nearby and long-range). The intuitive web interface handles both manual entry of SNP IDs as well as allowing users to upload files of SNP IDs. The user can limit the resulting inter SNP associations with easy to use menu options. These include MAF limit (5-45%), distance limits between SNPs (minimum and maximum), r<sup>2 </sup>(0.3 to 1), HapMap population sample (CEU, YRI and JPT+CHB combined) and HapMap build/release. All resulting genome-wide inter-SNP associations are displayed on a single output page, which has a link to a downloadable tab delimited text file.</p> <p>Conclusion</p> <p>GLIDERS is a quick and easy way to retrieve genome-wide inter-SNP associations and to explore LD patterns for any number of SNPs of interest. GLIDERS can be useful in identifying SNPs with long-range LD. This can highlight mis-mapping or other potential association signal localisation problems.</p
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