1,020 research outputs found
Eurasian watermilfoil biomass associated with insect herbivores in New York
A study of aquatic plant biomass within Cayuga Lake, New
York spans twelve years from 1987-1998. The exotic Eurasian
watermilfoil
(
Myriophyllum spicatum
L.) decreased in the
northwest end of the lake from 55% of the total biomass in
1987 to 0.4% in 1998 and within the southwest end from
50% in 1987 to 11% in 1998. Concurrent with the watermilfoil
decline was the resurgence of native species of submersed
macrophytes. During this time we recorded for the
first time in Cayuga Lake two herbivorous insect species: the
aquatic moth
Acentria ephemerella
, first observed in 1991, and
the aquatic weevil
Euhrychiopsis lecontei
, first found in 1996
.
Densities of
Acentria
in southwest Cayuga Lake averaged 1.04
individuals per apical meristem of Eurasian watermilfoil for
the three-year period 1996-1998. These same meristems had
Euhrychiopsis
densities on average of only 0.02 individuals per
apical meristem over the same three-year period. A comparison
of herbivore densities and lake sizes from five lakes in
1997 shows that
Acentria
densities correlate positively with
lake surface area and mean depth, while
Euhrychiopsis
densities
correlate negatively with lake surface area and mean
depth. In these five lakes,
Acentria
densities correlate negatively
with percent composition and dry mass of watermilfoil.
However,
Euhrychiopsis
densities correlate positively with percent
composition and dry mass of watermilfoil. Finally,
Acentria
densities correlate negatively with
Euhrychiopsis
densities
suggesting interspecific competition
Comparison of DMSP cross-track ion drifts and SuperDARN line-of-sight velocities
Cross-track ion drifts measured by the DMSP satellites are compared with line-of-sight SuperDARN HF velocities in approximately the same directions. Good overall agreement is found for a data set comprising of 209 satellite passes over the field of view of nine SuperDARN radars in both the Northern and Southern Hemispheres. The slope of the best linear fit line relating the SuperDARN and DMSP velocities is of the order of 0.7 with a tendency for SuperDARN velocities to be smaller. The agreement implies that the satellite and radar data can be merged into a common set provided that spatial and temporal variations of the velocity as measured by both instruments are smooth.<br><br> <b>Keywords.</b> Ionosphere (Ionospheric irregularities; Plasma convection; Auroral ionosphere
A statistical comparison of the AMIE derived and DMSPâSSIES observed highâlatitude ionospheric electric field
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95462/1/jgra18089.pd
Development of a Comprehensive New 4-H Extension Agents Training Program Using a Multi-Module Approach and the 4-H Professional Research, Knowledge, and Competencies (4HPRKC) Taxonomy
Following significant budget reductions in 2002, Virginia Cooperative Extension explored strategies to meet the professional development needs of new 4-H Extension faculty and staff. The Department of 4-H Youth Development created a training program to teach youth development competencies consistent with the national 4-H professional research, knowledge, and competencies (4HPRKC) taxonomy. Written and verbal evaluations from participants in the New 4-H Extension Agents Training Program suggested that the training was informative, interactive, and responsive to participants\u27 needs. This program is a potential model for other Extension programs that serve the professional development needs of new 4-H Extension faculty and staf
How prisoners and their partners experience the maintenance of their relationship during a prison sentence
Research shows that intimate relationships, and their maintenance via prison visits, have a positive impact on factors associated with prisoner wellâbeing and reduced likelihood of recidivism. It is therefore in the interest of corrections, government, and wider society to enable prisoners to maintain healthy relationships with their family and intimate partners throughout their prison sentence. Despite this evidence, little is known about how prisoners experience the maintenance of a significant intimate relationship in prison. This study aims to explore heterosexual couples' experiences in maintaining their wellâestablished intimate relationships, while the male partner is incarcerated. Four main themes were identified: how they experienced âhaving a special connectionâ that they were motivated to maintain; âcoping with challenges and threatsâ to that connection; âdeveloping reciprocal behavioursâ to meet those challenges; and âmaintaining a belief in the future.â Implications for how the relational context of rehabilitation can best be supported is considered
Response of reverse convection to fast IMF transitions
The nature of the transition that highâlatitude reverse convection makes in response to fast interplanetary magnetic field (IMF) changes is investigated using observations from multiple spacecraft and a ground magnetometer array. We focused on two fast IMFâtransition events on 22 April 2006. Immediately after the first event, three ST5 spacecraft identified a clear change in the distribution of the polar cap fieldâaligned current. Coordinate observations with the Greenland magnetometer chain showed that the nearânoon Hall current distribution, which is closely related to the polar cap fieldâaligned current or reverse convection, was in a transition state for about 10 min. For the second event, the Greenland magnetic perturbations also showed that a transition state occurred in the nearânoon sector for 10â15 min. Three DMSP spacecraft that traversed the polar cap provided evidence showing that variations of the ground magnetic perturbations were produced by the transition from clockwise plasma circulation to the anticlockwise circulation over the polar cap. A simple calculation based on the BiotâSavart law shows that the nearânoon transition state is consistent with the approach of a new convection region to the nearânoon sector at the speed of 0.5â1 km sâ1, which is coupled with the moving away of the old convection region at a similar speed. For the higherâlatitude sunward flow region, it is found that the convection takes a transition state almost simultaneously (within 1 min) with that in the nearânoon sector, i.e., quasiâinstantaneous response.Key PointsTransition state with a timescale of ~10 min in the nearânoon polar cap for BZâ>â0The state is consistent with the passage of old and new convection regionsAlmost simultaneous initial response in the upstream polar cap and the near noonPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111947/1/jgra51794.pd
Healthier prisons: The role of a prison visitors' centre
Since the inception of the prison as a âsettingâ for health promotion, there has been a focus on how the health of those men and women who spend âtime insideâ can at least be maintained and if possible, enhanced, during their prison sentence. This paper presents findings from a mainly qualitative evaluation of a prison visitors' centre in the UK. It reports experiences of prisoners' families, prisoners, prison staff, the local community and the ways in which the visitors' centre has contributed positively to their health and well-being. In addition, key stakeholders were interviewed to ascertain the role this visitors' centre has in policy frameworks related to re-offending. The findings from this evaluation underscore how the visitors' centre improved the quality of visits, and contributed towards the maintenance of family ties through the help and support it provides for families and prisoners. The paper concludes by suggesting that visitors' centres are an essential part of a modern prison service helping to address the government's health inequalities agenda
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