9,285 research outputs found
Interactive effects of losing key grazers and ecosystem engineers vary with environmental context
No full textLoss of biodiversity may cause significant changes to ecosystem structure and functioning. Evidence from long-term in situ removal experiments is rare but important in determining the effects of biodiversity loss against a background of environmental variation. Limpets and mussels are thought to be important in controlling community structure on wave-exposed shores in the UK: limpets as key grazers, mussels as ecosystem engineers. A long-term factorial removal experiment revealed interactive effects that varied between 2 shores in SW England. At one site (Harlyn), removing limpets caused a significant shift in community structure, but where limpets were lost, the presence or absence of mussels made little difference. Where limpets were present, however, the removal of mussels changed the structure and variability of the community. At the other site (Polzeath), the loss of mussels caused significant changes in community structure, and limpets played a less important role. At Harlyn, fucoid algae were abundant throughout the year. There were fewer algae at Polzeath, and cover was dominated by the summer bloom of ephemerals. At Harlyn, the limpets played a major role in controlling algae, but their effects were mediated by the presence of mussels. Other grazers were not able to fulfil their role. At Polzeath, mussels were far more important, and ephemeral algae grew on them regardless of the presence or loss of limpets. These findings emphasise the need to assess spatial and temporal variation in the effects of biodiversity loss and the importance of interactive effects of loss of multiple species from different functional groups
Consequences of climate-driven biodiversity changes for ecosystem functioning of North European rocky shores
No full textWe review how intertidal biodiversity is responding to globally driven climate change,
focusing on long-term data from rocky shores in the British Isles. Physical evidence of warming
around the British Isles is presented and, whilst there has been considerable fluctuation, sea surface
temperatures are at the highest levels recorded, surpassing previous warm periods (i.e. late 1950s).
Examples are given of species that have been advancing or retreating polewards over the last 50 to
100 yr. On rocky shores, the extent of poleward movement is idiosyncratic and dependent upon life
history characteristics, dispersal capabilities and habitat requirements. More southern, warm water
species have been recorded advancing than northern, cold water species retreating. Models have
been developed to predict likely assemblage composition based on future environmental scenarios.
We present qualitative and quantitative forecasts to explore the functional consequences of changes
in the identity, abundance and species richness of gastropod grazers and foundation species such as
barnacles and canopy-forming algae. We forecast that the balance of primary producers and secondary
consumers is likely to change along wave exposure gradients matching changes occurring
with latitude, thereby shifting the balance between export and import of primary production.
Increases in grazer and sessile invertebrate diversity are likely to be accompanied by decreasing
primary production by large canopy-forming fucoids. The reasons for such changes are discussed in
the context of emerging theory on the relationship between biodiversity and ecosystem functioning.
KEY WORDS: Climate change · Intertidal · Range shifts · Biodiversity · Ecosystem functioning ·
Northeast Atlanti
GA-Fuzzy PID control simulation waveform diagram.
No full textAs is well known, the metal annealing process has the characteristics of heat concentration and rapid heating. Traditional vacuum annealing furnaces use PID control method, which has problems such as high temperature fluctuation, large overshoot, and long response time during the heating and heating process. Based on this situation, some domestic scholars have adopted fuzzy PID control algorithm in the temperature control of vacuum annealing furnaces. Due to the fact that fuzzy rules are formulated through a large amount of on-site temperature data and experience summary, there is a certain degree of subjectivity, which cannot ensure that each rule is optimal. In response to this drawback, the author combined the technical parameters of vacuum annealing furnace equipment, The fuzzy PID temperature control of the vacuum annealing furnace is optimized using genetic algorithm. Through simulation and comparative analysis, it is concluded that the design of the fuzzy PID vacuum annealing furnace temperature control system based on GA optimization is superior to fuzzy PID and traditional PID control in terms of temperature accuracy, rise time, and overshoot control. Finally, it was verified through offline experiments that the fuzzy PID temperature control system based on GA optimization meets the annealing temperature requirements of metal workpieces and can be applied to the temperature control system of vacuum annealing furnaces.</div
The intertidal zone of the North-East Atlantic region: pattern and process.
No full textThe north-east Atlantic region is an area where
clades originating in the north Pacific (fucoids,
balanoids, littorinids, thaids, laminarians) collide
with clades from further south in the Atlantic
(e.g., patellids, trochids, chthamalids). At high
latitudes in the north, seaweeds dominate the
midshore zone of all but the most exposed
shores. Further south, midshore space-occupying
invertebrates (mussels and barnacles) win, facilitated
by grazing by patellid limpets that controls
algal recruitment; propagule pressure is much
less as fucoids become rarer, and juvenile growth
is slower due to environmental stress, thereby
reducing the probability of escapes from grazing
(Figure 2.4) (Ferreira et al., 2014, 2015a, 2015b).
Low on the shore seaweeds dominate space by
forming algal turfs or kelp or fucoid canopies.
These algae outpace the ability of grazing limpets
to control them in the low-intertidal zone. L.
digitata canopies can lead to rock covered by
encrusting algae and sponges, facilitating
limpets. If canopy is removed, then colonising
ephemeral algae and turf-forming algae swamp
the limpets. There is usually too much water
movement immediately either side of low water
for effective foraging by sea urchins. Psammechinus
miliaris and Echinus esculentus only appear in
the subtidal, and Paracentrotus lividus is confined
to refuges in burrows relying mainly on the drift
of food (Benedetti-Cecchi and Cinelli, 1995;Boudouresque and Verlaque, 2007; Jacinto and
Cruz, 2012).
High on the shore, physical factors dominate.
At high latitudes in the north of the Atlantic,
ephemeral algae are present all year round. Further
south they are only present in the winter,
dying-off in the summer. Grazing has limited
effects, only occurring around refuges that
littorinids maintain (Stafford and Davies, 2005;
Skov et al., 2010, 2011).
Patterns are also strongly modified by mesoscale
processes driven by upwelling that influences
nutrient and larval supply (North Africa,
Iberia) and coastal configuration, where embayed
versus headlands also strongly influence larval
supply (France northwards). In high-recruitment
areas, interactions can be intense between spaceoccupying
species, also driving predator abundance
(e.g., dog whelks). Connell’s (1961a) classic
paper on competition was possible on the Isle of
Cumbrae because space was almost saturated;
elsewhere lower larval supply would have created
less intense interactions, as shown by Gordon and
Knights (2017) in Plymouth.
The north-east Atlantic has faster rates of
warming than any other ocean, although the
region south of Greenland and Iceland is undergoing
cooling due to a climate-driven slowdown
in the Atlantic meridional overturning circulation,
causing a weakening in the Gulf Stream
(Rahmstorf et al., 2015).
Species are responding to rapid alterations in
the marine climate by adapting or exhibiting
range shifts, or by becoming locally extinct.
There is a high degree of spatial and temporal
heterogeneity in the resultant impacts on marine
communities due to the idiosyncratic responses
of individual species. Warming seas have resulted
in biogeographic range shifts of intertidal and
subtidal species in coastal waters of the northeast
Atlantic. The leading range edges of Lusitanian
species are expanding, while the trailing
edges of boreal species are retracting to higher
latitudes, but with some cold-water species showing
surprising resilience (Southward et al., 1995;
Mieszkowska et al., 2006, 2014b; Lima et al.,
2007; Hawkins et al., 2008, 2009; Wethey and
Woodin, 2008; Mieszkowska and Sugden, 2016).
In addition to changes in the distribution ofspecies, community structure is also altering as
species dominance and interactions change
(Poloczanska et al., 2008; Hawkins et al., 2008,
2009; Mieszkowska et al., 2014b).
In a warming world the midshore of France
and the British Isles are likely to show much less
cover by large canopy-forming fucoids as harsher
warmer, drier and stormier conditions coupled
with increased grazing pressure from more
grazing species reduces the probability of fucoids
recruiting to form adult populations. Lowshore
kelp forests will likely change with less L. digitata
and A. esculenta and more S. polyschides. The late
autumn to early spring window of dense
ephemeral algal growth high on the shore (Hawkins
and Hartnoll, 1983a) will also constrict,
except in the north and in extreme exposure.
These changes will have consequences for biodiversity
(Thompson et al., 1996; Smale et al.,
2013; Teagle et al., 2017) and productivity (Hawkins
et al., 1992) – particularly the decrease in
export of algal detritus (Notman et al., 2016).
More shores will become dominated by
suspension-feeding barnacles and mussels. Thus,
there will be switches on many mid-latitude
shores as many become net importers rather
than exporters of energy (Hawkins et al., 2008,
2009)
Short-term combination of glatiramer acetate with i.v. steroid treatment preceding treatment with GA alone assessed by MRI-disease activity in patients with relapsing-remitting multiple sclerosis.
No full textTo assess if short-term combination of glatiramer acetate (GA) and i.v. steroid in patients with relapsing-remitting multiple sclerosis (RRMS) is safe and sustains the effect of GA treatment on MRI-disease activity.RRMS patients with >or=2 gadolinium (Gd)-enhancing lesions on screening MRI and EDSS scor
Short-Term Combination of Glatiramer Acetate with IV Steroid Treatment Preceding Treatment with GA Alone Is Associated with early Suppression of MRI-disease activity in Patients with Relapsing Remitting Multiple Sclerosis
No full textOBJECTIVES:
To assess if short-term combination of glatiramer acetate (GA) and i.v. steroid in patients with relapsing-remitting multiple sclerosis (RRMS) is safe and sustains the effect of GA treatment on MRI-disease activity.
METHODS:
RRMS patients with >or=2 gadolinium (Gd)-enhancing lesions on screening MRI and EDSS score <or=4.0 received GA injection (20 mg subcutaneously once daily) and monthly 1 g i.v. Methylprednisolone (IVMP) for 6 months. Afterwards, all subjects received GA injections daily alone for additional 6 months. Neurological evaluations were performed at screening, baseline and every 3 months. Laboratory tests for safety were performed at screening, baseline, months 1, 6 and 12. Brain MRIs were performed at screening, baseline, months 5, 6, 11, and 12 to assess the change in the number of Gd-enhancing lesions i) from baseline to month 6, and ii) from baseline to month 12 compared with the change from baseline to month 6.
RESULTS:
89 subjects were eligible for the study. In this group, GA in combination with IVMP resulted in 65% (95% CI=0.25-0.49, p<0.0001) reduction in the number of Gd-enhancing lesions. This reduction was sustained for additional 6 months when patients received GA alone. The analysis for change achieved in the second 6 month period showed no difference from the change achieved in the first six months (ratio 0.75, 90% CI=0.468-1.197). Overall, treatment was well tolerated and adverse events reported were similar to the known safety profile of GA.
CONCLUSIONS:
Short-term combination of GA with 1 g monthly IVMP, preceding treatment with GA alone, is safe. MRI data suggest that this combination therapy may result in an early and sustained reduction of disease activity in RRMS patients
City Hall Auditorium & Opera House Hawkinsville, GA
No full textCity Hall Auditorium & Opera house Hawkinsville, GA. The seat of Pulaski County, Hawkinsville lies in south central Georgia on the banks of the Ocmulgee River. Hawkinsville is named after Colonel Benjamin Hawkins, Completed in 1908, the building originally served as the city hall and auditorium. It is registered in NRHP # 73000638.https://digitalcommons.unf.edu/historical_architecture_main/1322/thumbnail.jp
Profiles 2004
No full textJo Anne Grunbaum, Jennifer Di Pietra, Tim McManus, Joseph Hawkins, Laura Kann."Profiles 2004" at head of title page.Includes bibliographical references (p. 42-45).Grunbaum JA, Di Pietra J, McManus T, Hawkins J, Kann L. School Health Profile: Characteristics of Health Programs Among Secondary Schools (Profiles 2004). Atlanta, GA: Centers for Disease Control and Prevention, 2005
City Hall Auditorium Corner Stone 1A, Hawkinsville, GA
No full textCity Hall Auditorium Corner Stone 1A, Hawkinsville, GA. The seat of Pulaski County, Hawkinsville lies in south central Georgia on the banks of the Ocmulgee River. Hawkinsville is named after Colonel Benjamin Hawkins, This Cornerstone was erected in 1907. This was formerly known as Old Opera House .https://digitalcommons.unf.edu/historical_architecture_main/1320/thumbnail.jp
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