bluuebunny/crossref_metadata_2025 huggingface dataset:
Provenance of intermediate waters in the western North Pacific deduced from thermodynamic imprint on δ13C of DIC
Authors: Itou Masashi , Ono Tsuneo , Noriki Shinichiro
Published: November 2003

Stable carbon isotopes of dissolved inorganic carbon (δ13CDIC), together with phosphate concentrations (PO43−) of the western North Pacific marginal area are presented. Although δ13CDIC controlled not only air‐sea exchange but also biological activities, by subtracting PO43− as a biological factor from the δ13CDIC, the thermodynamic imprint on the carbon isotopic composition (δ13Cas) is used as a conservative tracer. The linear relationship between δ13Cas and temperature with the δ13Cas/temperature slope of −0.104‰/°C is observed in the North Pacific subtropical region. This relationship can be extended to the Weddell Sea deep waters. Therefore oceanic DIC is apparently in temperature‐dependent isotopic equilibrium with atmospheric CO2. To characterize each water mass, the “isotopically labeled temperature” (Tiso), which is derived from δ13Cas‐temperature relationship obtained for the subtropical gyre water and Weddell Sea Water, is introduced. In contrast, the δ13Cas‐temperature relationship is not necessarily linear for the northern Japan Sea Water, the Kuroshio‐Oyashio Mixed Water and the Okhotsk Sea Water. This nonlinearity implies apparent air‐sea carbon isotopic disequilibria resulting from water cooling without accompanying air‐sea carbon isotope equilibrium. By using the potential temperature (Tpot) and the Tiso, the source waters constituting intermediate waters (26.8σθ) have been estimated. The results clearly indicate that (1) the intermediate water in the southern Okhotsk Sea contains up to 20% Japan Sea Water, and that (2) “new” North Pacific Intermediate Water (NPIW) consists of Okhotsk Sea Water, subarctic gyre water, and “old” subtropical NPIW.
Snow accumulation variability in Wilkes Land, East Antarctica, and the relationship to atmospheric ridging in the 130°–170°E region since 1930
Authors: Goodwin I. , de Angelis M. , Pook M. , Young N. W.
Published: November 2003

Wilkes Land annual snow accumulation variability is explored together with ice core chemistry data as proxies for circumpolar atmospheric circulation in the 110°E–135°E sector of the circumpolar trough. Four accumulation time series spanning 1930–1985 show a pattern of accumulation related to maritime air mass incursions over the East Antarctic ice sheet slope, which is regionally consistent on interannual and interdecadal timescales. The temporal accumulation pattern in Wilkes Land shows decadal fluctuations of ±10%. Both these fluctuations and the overall trend of increasing accumulation since the middle 1960s are consistent with a poleward shift and intensification of the circumpolar trough. This is consistent with a shift toward the high index state of the southern annular mode. Interannual variability of snow accumulation rate throughout Wilkes Land was found to be dependent upon shifts in the preferred tracks of cyclones along or across the coast and in the location of cyclolysis regions. Significant differences in this temporal accumulation pattern over Wilkes Land can occur as a result of the time‐varying location of atmospheric ridging and the circumpolar long‐wave structure south of New Zealand and Australia. Snow accumulation at an additional site (GD09) displays a well‐defined interdecadal pattern, and the mean annual nitrate (NO3−) concentration of snow is correlated to the winter sea level pressure gradient between East Antarctica and the sub‐Antarctic and the upper geopotential height and zonal wind data over East Antarctica. Strong, surface wind drainage during tropospheric ridging in Wilkes Land produces anomalous snow accumulation and annual mean NO3− concentration in firn at GD09.
Spatial patterns of soil moisture connected to monthly‐seasonal precipitation variability in a monsoon region
Authors: Liu Yongqiang
Published: November 2003

The relations between monthly‐seasonal soil moisture and precipitation variability are investigated by identifying the coupled patterns of the two hydrological fields using singular value decomposition (SVD). SVD is a technique of principal component analysis similar to empirical orthogonal functions (EOF). However, it is applied to two variables simultaneously and is capable of extracting spatial patterns of one variable which are closely connected to variability of the other. Simulation is performed with a regional climate model to reproduce soil moisture and precipitation in east Asia. It is found that, of a number of leading soil moisture SVD patterns, those representing meridional anomalies have closer relationships to subsequent precipitation variability. The corresponding atmospheric variability is characterized by opposite anomalies between the middle and low troposphere and by comparable anomalies between the middle and low latitudes. These patterns occur more frequently during spring and summer. The time lag correlations of the SVD expansion series with soil moisture leading precipitation are much greater than those of the original data series and EOF expansion series, suggesting that predictability of monthly‐seasonal precipitation variability could be improved by using soil moisture in the form of its coupled SVD patterns with precipitation.
Impact of Hall effect on energy decay in magnetohydrodynamic turbulence
Authors: Matthaeus W. H. , Dmitruk P. , Smith D. , Ghosh S. , Oughton S.
Published: November 2003

We examine numerically the influence of Hall effect corrections to Ohm's law upon the decay of homogeneous compressible magnetohydrodynamic turbulence and conclude that there are no significant differences in global decay rate associated with the Hall effect. This affirms expectations that energy decay is controlled by the large‐scale eddies.
A comparison of Pi2 pulsations observed by CHAMP in low Earth orbit and on the ground at low latitudes
Authors: Sutcliffe P. R. , Lühr H.
Published: November 2003

Initial results of a comparative study of Pi2 pulsations observed by the CHAMP satellite in low Earth orbit and at a low‐latitude ground station in South Africa are presented. It has for the first time been possible to extract and clearly resolve Pi2 pulsations from low Earth orbit satellite data due to the unprecedented accuracy and resolution of the CHAMP magnetic field measurements. An important new result is that the correlation between satellite and ground Pi2s is improved by subtraction of a lithospheric magnetic field anomaly model from the satellite data. The analysis indicates that the H‐component of the Pi2 pulsation on the ground is well correlated with the compressional and poloidal components above the ionosphere. Furthermore, in the southern hemisphere the compressional and poloidal components oscillate in phase with H; however, in the northern hemisphere the poloidal component oscillates in anti‐phase with the compressional and H components.
The relationship between field‐aligned currents and low‐frequency electromagnetic fluctuations
Authors: Seyler C. E. , Xu T.
Published: November 2003

Current sheets having a transverse scale near the electron inertial length c/ωp have been shown to be unstable using a reduced MHD description with electron inertia [Seyler and Wu, 2001]. This robust instability arises from the advection of the parallel current which lowers the magnetic energy resulting in vortex formation. The instability is localized where the parallel current shear and B⟂ are near a maximum. Observations from Freja, FAST, and CLUSTER show fluctuation enhancement in regions where current shear maximizes. The simulation spectral ratios δE/δB and δE/δn are found to be consistent with satellite data. The agreement between observations and simulations support the simulation results as the generation mechanism of BBELF (broad‐band extremely low‐frequency) fluctuations.
Near‐surface temperatures at proposed Mars Exploration Rover landing sites
Authors: Martin Terry Z. , Bridges Nathan T. , Murphy James R.
Published: November 2003

Minimum nighttime temperatures at the Mars Exploration Rover (MER) landing sites may limit power available for science activities and thus mission lifetime. Here, 1 m air temperatures at the end of the nominal 90 sol primary mission are derived for the four primary and three previously considered MER landing sites based on Mars Global Surveyor Thermal Emission Spectrometer thermal inertia and albedo, estimated opacity, and predictions of air temperatures from a one‐dimensional atmospheric model. Taking these results and mapping them onto the probability density distribution of the landing ellipses shows that of the air temperatures of the primary sites, Sinus Meridiani (“Hematite”) is the coldest, with an 8% chance of encountering minimum nighttime temperatures below the 176 K value considered a practical limit for operations. Elysium and Gusev are at 7% and 3%, respectively, whereas Isidis has no computed temperatures below 191 K. For the Hematite site, preliminary observations and interpretations are also made using high‐resolution Odyssey Thermal Imaging System predawn images.
Bone healing with electric current: a histological assessment
Authors: Chen Hui‐Ling , Killiany Dennis Michael , Waheed‐Uz‐Zaman Rana Mohamed
Published: November 2003

Skeletal relapse is a major concern after correction of retrognathism with surgical mandibular advancement. It was hypothesized that the stimulation from a direct electric current can accelerate the osseous repair through the enhancement of the maturation of fibrocartilage. Furthermore, this stimulation may enhance the mechanical properties of the facial osteotomy site and reduce the skeletal relapse. The purpose of the present study was to examine the osteotomy site histologically and determine the effect of post‐surgical electrical stimulation on the healing of a facial osteotomy site in a rat model. Three groups of adult male Sprague–Dawley rats, 15 in each group (direct electric current, electric sham, and control), were used to generate data. Electrodes were placed in both the direct electric current and the electric sham groups. A 20‐μA direct current was delivered to the osteotomy site only in the direct electric current group.  Histological slides of the osteotomy site for each animal were prepared and interpreted to characterize the healing process of the osteotomy site for each animal. The results showed no statistically significant difference among the three groups of animals (p>0.005). An examination with histology earlier in the healing process and the utilization of an experimental animal with a larger jaw are suggested for any further investigation that involves electrical stimulation and osseous healing in a facial osteotomy site.
Condylar bony change and mandibular deviation in orthodontic patients – using helical CT and MRI
Authors: Uy‐Co Evelyn Tan , Yamada Kazuhiro , Hanada Kooji , Hayashi Takafumi , Ito Jusuke
Published: November 2003

This study was designed to assess the relationship between condylar bony change and mandibular deviation in the orthodontic patient. Seventy‐one patients were examined with helical computed tomography and magnetic resonance imaging to assess the condylar bony change and/or disk displacement prior to acceptance for orthodontic treatment. They were grouped into no condylar bony change (NBC) and unilateral condylar bony change (UBC). Frontal and lateral cephalograms and panoramic radiographs were also utilized to evaluate craniofacial morphology, and condylar and ramal heights. The results revealed that TMJ sounds occurred more in the UBC than the NBC group at all ages; but, TMJ pain and difficulty of mouth opening did not show remarkable differences. Erosion, a characteristic feature in age 9–13 years in UBC, occurred with normal disk position or disk displacement without reduction. Flattening exhibited normal disk position in age 9–13 years but was accompanied with disk displacement in age 14–18 years and 19 years and above. Osteophyte formation was highly associated with disk displacement without reduction in all age groups. Moreover, the UBC group's mandible was deviated to the ipsilateral side with significantly shorter condylar height on the affected side. In all age groups of UBC, the difference of condylar height was highly correlated with anterior maxilla, occlusal and gonial planes and with mandibular deviation. All aforementioned results suggest that unilateral condylar bony change can occur with normal disk position or ahead of disk displacement in the young patients. It seems that unilateral condylar bony changes can cause not only mandibular deviation but can also affect the cant of maxillary basal bone, mandibular plane angle and lower dentition.
Cervical headgear and function regulator effects in Class II, division 1 patients
Authors: Lisson JA
Published: November 2003

This study investigated 40 growing patients with Angle‐Class II, division 1, treated with either a functional regulator (FR) or cervical headgear (HG) over a period of approximately 1 year. The objective was to evaluate dentoalveolar and skeletal reactions.  Both appliances significantly (p<0.001) improved distocclusion
and reduced the overjet. Cephalometric analyses revealed that the effects
of these two appliances on the skeleton differed. Also, in the FR group,
the inclination of incisors was (p<0.05) altered as well as the
maxillary plane angle and the Wits‐appraisal (p<0.05). The HG
group showed a significant (p<0.001) reduction in both SNA and ANB angles. Both appliances appear to be sufficient for improvement in patients with Class II, division 1 occlusion, with the HG showing an additional skeletal effect in the maxilla.
Effects of wire and miniplate fixation on mandibular stability and TMJ symptoms following orthognathic surgery
Authors: Kobayashi Tadaharu , Honma Katsuhiko , Hamamoto Yoshioki , Shingaki Susumu , Nakajima Tamio , Hanada Kooji
Published: November 2003

The effects of wire and miniplate fixations on mandibular stability and temporomandibular joint (TMJ) symptoms were analyzed in 145 patients in whom mandibular prognathism had been corrected by the bilateral sagittal split osteotomy (BSSO). The subjects were divided into two groups based on the method of fixation. Group I consisted of 105 patients treated with intraosseous wiring and group II consisted of 40 patients treated with titanium miniplates. The mean maxillomandibular fixation periods for groups I and II were 48 days and 23 days, respectively. Lateral cephalograms were taken immediately before surgery, within a week after surgery, and at least a year after surgery. Changes in the positions of the incisal edge of the lower central incisors, point B, pogonion, and menton were examined. TMJs were examined clinically for pain, sounds, movements, and limitations before treatment and at least a year after surgery. In both groups, the mean of the horizontal relapses was correlated to the magnitude of their surgical movements. In group II, the mean horizontal relapse was smaller, but not significantly more than that of group I. There was no statistical difference in the pre‐ and postoperative incidence of TMJ signs and symptoms between the two groups. It can be concluded that miniplate fixation for the BSSO procedure has the advantages of shortening the maxillomandibular fixation period and maintaining the postoperative stability of the mandible without causing adverse effects on the TMJ.
Interactions between two rust fungi and their host plant Anemone nemorosa
Authors: García‐Guzmán Graciela , Wennström Anders
Published: November 2003

In a field study we found that two rust fungi, Tranzcheliaanemones and Ochropsora ariae, on the shared host Anemone nemorosa varied in abundance among populations. Tranzchelia anemones was favoured in high light habitats and was particularly common in mixed deciduous forests as well as productive grasslands, whereas the abundance and occurrence of O. ariae was dependent on the presence of the alternate host, Sorbus aucuparia When found in the same population, the two rusts rarely attacked the same ramet. Both T. anemones and O. ariae had a negative effect on plant performance by reducing flower production, and rhizome length. Diseased shoots were also elongated.
Effects of biodiversity loss and disturbance on the survival and performance of two Ranunculus species with differing clonal architectures
Authors: Diemer Matthias , Schmid Bernhard
Published: November 2003

Seedlings of Ranunculus repens and R. acris were transplanted into an array of experimental grasslands with differing plant species richness and number of functional groups. Half of the plots were also subjected to simulated horse trampling, to examine how the interrelationship between diversity and disturbance affected the survivorship, growth and biomass of the Ranunculus transplants. Survivorship increased with increasing initial size of individuals or decreasing species richness of the plots. Vegetative growth, reproduction and aboveground biomass were strongly enhanced in response to a log‐linear loss of species richness and secondarily by a decline in the number of functional groups. Disturbance had no effect on performance of transplants with one exception, ramet formation of R. acris, which was enhanced under the trampling regime. Despite differences in clonal architecture, both Ranunculus species behaved similarly. Our results demonstrate the importance of species richness in controlling invasibility of grassland communities.
Bat species richness in live fences and in corridors of residual rain forest vegetation at Los Tuxtlas, Mexico
Authors: Estrada Alejandro , Coates‐Estrada Rosamunda
Published: November 2003

Fragmentation of lowland tropical rain forests has resulted in loss of animal and plant species and isolation of remaining populations that puts them at risk. At Los Tuxtlas, Mexico, lowland rain forests are particularly diverse in the bat fauna they contain and while most of the forests have been fragmented by human activity, many of the fragments still harbor diverse assemblages of bat species. To assess the effectiveness of corridors, among other options, to ameliorate the negative effects of fragmentation, we investigated bat species richness and relative abundance in one 6 km long section of live fences (LF) bordering a dirt road and in three 6 km long sections of residual forest vegetation along the sides of three permanent streams (BS, MS, HS). Netting of bats resulted in the capture of 967 bats. At the LF site we captured 12 bat species, 15 at the BS site, 18 at the MS site and 23 at the HS site. Species richness was associated with average area of forest fragments within a 1000 m band on each side of each corridor (r=0.97, p=0.01). Only 28% of the species were common among sites. Frugivorous and insectivorous species accounted for 48% each of bat captures while nectarivores accounted for 3%, sanguinivores for 0.5% and carnivore‐frugivores for 0.5%. Edge habitat species such as Pteronotusparnelli and Sturniralilium accounted for 50% of the captures. Frugivorous species such as Carolliabrevicauda, Vampyrodescaraccioli, Dermanuraphaeotis, D. toltecus and A. jamaicensis accounted for another 25% of bat captures. Recaptures of bats indicated bat movements from forest fragments to corridors and between corridors, with recapture distances ranging from 200 to 2000 m. Within corridor recaptures separated by several months from the original recapture date indicated individual bat revisitation to these sites. We discuss the value of these corridors to bats as stepping stones in the fragmented landscape.
Symbiotic feather mites synchronize dispersal and population growth with host sociality and migratory disposition
Authors: Blanco Guillermo , Frías Oscar
Published: November 2003

Some symbiotic taxa may have evolved to track changes in the level and quality of food resources provided by the host to increase reproduction and dispersal. As a consequence, some ectosymbionts synchronize their reproduction and activity with particular stages of their host's living cycle. In this article we examined temporal patterns of variation in prevalence and abundance of feather mites living on pre‐migratory barn swallows Hirundo rustica. Feather mites in the lineages Pterolichoidea and Analgoidea are the most common arthropod ectosymbionts living at the expenses of feather oil. We investigated whether the seasonal variations in levels of several measures of physiological condition associated with host migration were related to changes in prevalence and abundance of mites. The results suggest that the variation in prevalence of feather mites, and thus probably the mode of acquisition and dispersal of these symbionts, is linked to an increase in host sociality before migration. Physiological dynamics of hosts after the breeding season point at two clearly identifiable periods: a post‐breeding period when physiological condition remains stationary or decreases, and a pre‐migratory period characterized by a rapid increase in several measures of physiological condition. Mite population dynamics were synchronized with migratory disposition during the period of highest host gregariousness. These synchronized processes occurred in both study years, although dynamics of migratory disposition and mite prevalence and abundance differ somewhat between years for adult and juvenile hosts. Mite population increase before host migration may be a response to a higher quantity of food provided by the host, namely oil from the urpoygial gland which is stimulated by hormones. Therefore, mites might have evolved to adjust their reproduction to the time when they have more chance of dispersal through horizontal transmission. In addition, body mass of juvenile and adult hosts were positively related with mite abundance in both years after allowing for several influencing factors. Body mass variation may reflect adequately fitness of host or their current physiological state, for instance, differences in the secretion of lipids on feathers or a more adequate microclimate to these symbionts.
Long term effects of cormorant predation on fish communities and fishery in a freshwater lake
Authors: Engström Henri
Published: November 2003

Cormorant impact upon natural fish populations has long been debated but little studied because of the requirements of sound data that are often hard to fill. In this study I have monitored fish community composition/abundance before and after a cormorant colony was established in a high productive lake, Ymsen, of south‐central Sweden. Data on fish abundance before cormorant establishment enabled me to control for changes in fish densities prior to cormorant colonisation. To control for possible changes in fish populations caused by factors other than cormorant predation (i.e. large‐scale regional changes due to climate) data were compared with a control lake, Garnsviken, with no cormorants. Since Lake Ymsen also harbour an important commercial fishery, cormorant impact upon fishery yields was evaluated. The most important fish species in the diet of the cormorants were ruffe (75% by number), roach (11%) and perch (10%). Except for perch, commercially important fish made up a very small fraction of the cormorant diet. Eel, the most important fish for the fishery, was absent in the cormorant diet, pikeperch constituted 0.2% and pike 1.5%. Estimated fish outtake by the cormorants was 12.8 kg ha−1 yr−1 compared to 8.6 kg ha−1 yr−1 for the fishery. Despite considerable fish withdrawal by the cormorants, fish populations did not seem to change in numbers or biomass.  The present study indicates that cormorant impact upon fish populations in Lake Ymsen was small and probably in no case has led to declines of neither commercial nor of non‐commercial fish species. Still, the number of breeding cormorants in Lake Ymsen, in relation to foraging area, is among the highest known for Swedish lakes.
Spatial pattern in the occurrence of the lichen Lobaria pulmonaria in managed and virgin boreal forests
Authors: Gu Wei‐Dong , Kuusinen Mikko , Konttinen Tuija , Hanski Ilkka
Published: November 2003

Two populations of the lichen Lobaria pulmonaria, growing on aspens and goat willows in 12 and 20 km2 study areas of boreal forest in Finland, were surveyed thoroughly to investigate the factors influencing the spatial distribution of the lichen. In one study area, where forestry has been intensive and old‐growth forest is highly fragmented, L. pulmonaria was sparse and grew mostly on willows. In contrast, a large and continuous virgin forest area supported a higher incidence of L. pulmonaria, with the lichen being common on both aspens and willows. In both study areas, the distributions of aspen and willow were clumped over the scales of 100–1000 m. The spatial pattern of L. pulmonaria was more clumped in the managed forest than in the virgin forest. The reduced incidence of the lichen on aspens in the managed area was attributed to a disruption of habitat continuity and small average tree size. There was no comparable reduction in the incidence on willows, probably because the willow had a very aggregated distribution in the managed area, which probably facilitated local colonization of the lichen. Presence of the lichen was significantly related to size‐corrected local density of aspen and willow trees as well as to spatial connectivity to neighboring lichen‐occupied trees.
Structure and diversity of a species‐rich grassland community, treated with additional illumination, fertilization and mowing
Authors: Eek Liina , Zobel Kristjan
Published: November 2003

We examined the changes of species‐rich herbaceous community canopy structure and species diversity in a five‐year field experiment. Above‐ and below‐ground resource addition (fertilization and additional illumination with the help of mirrors) and cessation of annual mowing were applied as experimental treatments in 24 permanent plots of 40×40 cm. Canopy structure was studied by point quadrat sampling using laser beam to randomly position point quadrats at two different angles of observation – 60° and 120° from horizontal, north‐south direction. We hypothezised that the studied plant community is not light‐limited under the normal conditions (non‐fertilized and annually mown) but would become light‐limited after nutrient addition and/or cessation of mowing. In this case the effect of fertilization and cessation of mowing could be mitigated by introducing additional light resource (placing south‐facing mirrors).  Species richness in plots was not significantly altered by experimental treatments, most probably because of a strong input of species from surrounding areas by the means of lateral vegetative spread, compensating for the expected decrease of diversity with fertilization and cessation of mowing. Surprisingly, plant total coverage in a plot was the only variable significantly explaining plot richness, independent of experimental treatments and the year of observation. We therefore studied also species richness per unit coverage (standardized richness) which appeared to be significantly reduced by fertilization. Annual change of plant total coverage of a plot was good predictor of annual change of plot richness, except for the exceptionally dry period (1994–1995). There was no indication of light being limiting for the plants in control plots, but light obviously became limiting after nutrient addition – in fertilized plots additional illumination lead to a notably denser canopy. Generally, the average exposition of plant leaves surface was towards the north, independent of experimental treatments. However, in the exceptionally cloudy and cool year 1996 the situation was radically different – leaves were exposed predominantly towards the south, indicating that multi‐species canopy can plastically react to long‐term changes in light availability.
Effect of proximity to ancient deciduous woodland on restoration of the field layer vegetation in a pine plantation
Authors: Dzwonko Zbigniew
Published: November 2003

The influence of dominant tree species, soil conditions and distance from an adjacent ancient oak‐hornbeam woodland upon the floristic composition, species richness and spatial distributions of species in a pine wood planted on dry rendzina soil were studied in southern Poland. It was found that, in spite of a 52‐yr long succession, the cover and composition of species in the pine wood were significantly different from that in the adjacent ancient woodland. Canonical correspondence analysis (CCA) and stepwise regression analyses showed that the distance to the ancient woodland had a significant influence on species distributions in the recent wood. The numbers of species from the Querco‐Fagetea class, vegetatively reproducing species and myrmecochores decreased with this distance, whereas the numbers of tree species in the shrub and field layers and anemochores increased. The light intensity had a positive effect on the numbers of species in the shrub layer, non‐woodland species and anemochores. The number of woodland species increased considerably with the cover of quickly decomposing litter and with thickness of the humus layer. The migration rate of many woodland species, calculated on occurrence of the farthest individuals was very slow, varying from 0.18 m yr−1 to 0.38 m yr−1. These results indicate that the availability of micro‐sites suitable for seed germination and plant development determined the successful colonization of the recent wood to an extent comparable with the seed dispersal.
Individual variation in habitat use and growth of male and female brown trout
Authors: Greenberg Larry A. , Giller Paul S.
Published: November 2003

We examined variation in growth and habitat use of individually PIT‐tagged brown trout Salmo trutta in three stream enclosures, each divided into a fine substrate, deep pool habitat and a coarse substrate, shallow habitat. Habitat use and movements of individual fish were monitored continually by placing PIT detectors between habitats. All fish were measured and weighed biweekly over a three month period. There was no significant relationship between habitat use and initial body size, nor was there a consistent relationship between habitat use and densities of benthic macroinvertebrates or abundance of drifting invertebrates in the two habitats. Most habitat changes occurred at night, with activity peaks just prior to sunrise and after sunset. Trout used pools more at night than during the day. Within any given day, diurnal and nocturnal habitat use of individual fish varied little, with variation greater at night than during the day. Partial habitat segregation by sex was observed; only males used pools extensively during daytime, whereas males and females used riffles.  Growth rate was positively related to use of pools during daytime but not at night. Growth rate was also affected by enclosure, with growth rates being highest in the most downstream enclosure, which had the deepest pool (mean of 42 cm) and lowest in the most upstream enclosure, which had the shallowest pool (mean of 28 cm). A complete exchange of trout between the most upstream and downstream enclosure indicated that the enclosure effect was due to physical differences and not to individual fish differences between enclosures. The effect appears to have been caused by differences in depth as daytime use of pools was correlated with the area of the pool ≥35 cm deep, and production of trout biomass per enclosure was directly related to mean pool depth. Our results suggest that there is a relationship between habitat use and growth of individuals that is independent of body size, but that this relationship is influenced by sex of the fish and by the physical characteristics of the environment. Further, the data indicate that short‐term behavioral decisions on habitat use by brown trout have a potential effect on longer‐term individual fitness through growth rates.
Ecological effects of El Niño in terrestrial ecosystems of western South America
Authors: Jaksic Fabian M.
Published: November 2003

I make a summary review of how El Niño/Southern Oscillation (ENSO) determines peculiar atmospheric and oceanographic conditions in western South America, thus affecting precipitation patterns in adjacent land masses, with cascading effects on marine and terrestrial plants, on sea and land birds, and on marine and terrestrial mammals. With regard to terrestrial ecosystems, I discuss the following biotic responses to El Niño‐driven precipitation: 1) aboveground vegetation flushes immediately among herbs but not among shrubs. 2) The seed bank is quickly replenished of ephemeral seeds, but perennial seeds recover one year later. 3) Small rodents irrupt within months of El Niño arrival, but larger ones take a full year to increase. 4) Predator numbers lag one year behind their mammal prey, with smaller predators responding more quickly. Considering these responses, I offer a simplified model of El Niño‐driven bottom‐up control in terrestrial ecosystems of western South America. Apart from the direct links already described, there is a weak feedback loop between the plant compartments (vegetation and seeds) and their herbivores: primary productivy is the driving force, and is little affected by herbivory. Another weak feedback loop links herbivores and their predators: the latter seem to just “surf” over prey levels, skimming excess prey.
Diet variation of common buzzards in Finland supports the alternative prey hypothesis
Authors: Reif Vitali , Tornberg Risto , Jungell Sven , Korpimäki Erkki
Published: November 2003

The regional synchrony of short‐term population fluctuations of small rodents and small game has usually been explained by varying impacts of generalist predators subsisting on both voles and small game (the “alternative prey hypothesis” APH). APH says that densities of predators increase as a response to increasing vole densities and then these predators shift their diet from the main prey to the alternative prey when the main prey decline and vice versa. We studied the diet composition of breeding common buzzards Buteo buteo during 1985–92 in western Finland. Microtus voles were the main prey and water voles, shrews, forest grouse, hares and small birds the most important alternative prey. Our data from the between‐year variation in the diet composition of buzzards fulfilled the main predictions of APH. The yearly proportion of main prey (Microtus voles) in the diet was higher in years of high than low vole abundance. The proportion of grouse in the diet of buzzards was negatively related to the abundance of Microtus voles in the field and was nearly independent of grouse abundance in the field. In addition, buzzards mainly took grouse chicks and young hares which is consistent with the prediction of APH. Therefore, we conclude that buzzards are able to shift their diet in the way predicted by the APH and that buzzards, together with other generalist predators, may reduce the breeding success of small game in the decline phase of the vole cycle, and thus substantially contribute to the existence of short‐term population cycles of small game.
Differences in species richness and life‐history traits between grazed and abandoned grasslands in southern Sweden
Authors: Dupré Cecilia , Diekmann Martin
Published: November 2003

Disturbance has profound effects on plant community composition. This paper deals with the influence of grazing on species richness and proportions of life‐history attributes of grassland vegetation at six spatial scales (0.001–1000 m2) in two provinces of southern Sweden. The study comprised 33 dry grassland sites, including 22 grazed and 11 abandoned localities, and 28 sites of coastal brackish meadows, divided into five management types (from “heavily grazed” to “abandoned since long time”).  In general grazed sites were species‐richer than abandoned sites, especially at small plot sizes. However, there was a steeper increase in species number towards larger plot sizes in the abandoned sites. Heavy grazing in the coastal meadows resulted in a comparatively low number of species, corroborating the intermediate disturbance hypothesis.  The analysis of life‐history traits indicated the importance of taxonomic group, canopy structure, height, regenerative strategy and, in particular, life form. Leaf anatomy and seed dispersal seemed to be less important. The responses to grazing as regards species traits differed somewhat between grassland types. Grazed sites generally had high proportions of legumes, therophytes, species with basal position of leaves and with regeneration by means of a persistent seed bank. Abandonment of grazing favoured monocots, geophytes, species with vegetative regeneration and (partly) leafy canopy structure. Some differences between grazed and abandoned sites were confined to either the smallest or largest plot sizes, indicating different responses of matrix and interstitial species. Various positive associations (attribute syndromes) or negative associations between individual traits were identified. There was, for example, a positive link between the attributes “geophytes” and “ability of vegetative regeneration”. The recognition of such links is important to avoid misinterpreting certain attributes as functional adaptations to grazing while they are only positively correlated to other attributes of larger significance.
Pollination ecology of Campanula species on Mt Olympos, Greece
Authors: Blionis George J. , Vokou Despina
Published: November 2003

Nine Campanula species occurring along the elevation gradient of Mt Olympos were studied regarding their pollination ecology. The main issues considered were 1) the relative importance of various insect taxa as Campanula pollinators, 2) the patterns of pollinators’ size and activity as a function of altitude, 3) the effect of pollinator exclusion on floral longevity, and 4) the extent to which the morphological difference of C. versicolor from the other Campanula species on Mt Olympos is expressed in its pollinating fauna. The vast majority of Campanula pollinators were solitary bees. Andrenidae and Megachilidae bees (mainly Chelostoma campanulorum) dominated the pollinating fauna of most species. Melittidae and bumblebees were the commonest pollinators of high altitude species. Campanula versicolor differs from the other Campanula species in that its corolla is not bell‐shaped but flat. Mainly Apis mellifera, syrphid flies, and carpenter bees, unlike all other Campanula species on Mt Olympos pollinated it. At the species level, rather large altitudinal differences of Campanula populations did not result into large diversification of their pollinating fauna. The insect visitation rate to flowers decreased with altitude. When pollinators were excluded, the floral longevity of the species examined increased three to five times. Neither flower phase (male of female) was consistently favoured in the absence of pollinators. The pollen loads of the different insect taxa (Apis mellifera included) were of variable purity. The majority of Megachilidae bees carried pollen loads of high purity. Pollen loads from insects visiting Campanula species at high altitudes did not differ significantly in their purity from those visiting lowland species. The distribution of Campanula pollinators’ body size along the altitudinal gradient exhibited a U‐shaped pattern. No relationship was found between insect‐pollinator body size and corolla size of Campanula species.
Geographical and temporal patterns of lemming population dynamics in Fennoscandia
Authors: Angerbjörn Anders , Tannerfeldt Magnus , Lundberg Håkan
Published: November 2003

There is a long‐lasting debate in ecology on cyclicity, synchrony and time lags of lemming population fluctuations. We have analysed 137 yr of previously published population data on the Norwegian lemming Lemmus lemmus in ten geographic regions of Fennoscandia. The dominating pattern was synchronous 4‐yr cycles. There was no support for the hypothesis of a north‐south gradient in cycle length. However, we found periods of prolonged interruptions in the cyclicity, which were more common in northern areas. We found a high degree of synchrony between regions, with only a weak relationship to distance. The observed pattern in lemming population dynamics was more consistent with effects from extrinsic factors, such as climate, than intrinsic factors, such as dispersal.
Latitudinal gradients in diversity: real patterns and random models
Authors: Koleff Patricia , Gaston Kevin J.
Published: November 2003

Mid‐domain models have been argued to provide a default explanation for the best known spatial pattern in biodiversity, namely the latitudinal gradient in species richness. These models assume no environmental gradients, but merely a random latitudinal association between the size and placement of the geographic ranges of species. A mid‐domain peak in richness is generated because when the latitudinal extents of species in a given taxonomic group are bounded to north and south, perhaps by a physical constraint such as a continental edge or perhaps by a climatic constraint such as a critical temperature or precipitation threshold, then the number of ways in which ranges can be distributed changes systematically between the bounds. In addition, such models make predictions about latitudinal variation in the latitudinal extents of the distributions of species, and in beta diversity (the spatial turnover in species identities). Here we test how well five mid‐domain models predict observed latitudinal patterns of species richness, latitudinal extent and beta diversity in two groups of birds, parrots and woodpeckers, across the New World. Whilst both groups exhibit clear gradients in richness and beta diversity and the general trend in species richness is acceptably predicted (but not accurately, unless substantial empirical information is assumed), the fit of these models is uniformly poor for beta diversity and latitudinal range extent. This suggests either that, at least for these data, as presently formulated mid‐domain models are too simplistic, or that in practice the mid‐domain effect is not significant in determining geographical variation in diversity.
AP‐1 recruitment to VAMP4 is modulated by phosphorylation‐dependent binding of PACS‐1
Authors: Hinners Ina , Wendler Franz , Fei Hao , Thomas Laurel , Thomas Gary , Tooze Sharon A
Published: November 2003

The R‐SNARE VAMP4, which contains a dileucine motif, binds to the AP‐1 (adaptor protein‐1) subunit μ1a, but not μ1b, or the GGAs (Golgi‐associated gamma ear containing ARF binding proteins). Serine 20 and leucines 25,26 are essential for this binding. AP‐1 association with VAMP4 is enhanced when serine 30, in an acidic cluster, is phosphorylated by casein kinase 2. This phosphorylation‐dependent modulation of AP‐1 binding is mediated by PACS‐1 (phosphofurin acidic cluster sorting protein). Ablation of both the dileucine motif and serine 30 results in a dramatic mislocalization of VAMP4 in the regulated secretory pathway in AtT20 cells. A dominant‐negative PACS‐1, which binds acidic clusters but not AP‐1, also causes mislocalization of VAMP4. Our data support a model whereby phosphorylation‐dependent recruitment of PACS‐1 enhances AP‐1 association to cargo, and suggest that efficient retrieval depends on the formation of a complex between cargo, such as VAMP4, AP‐1 and PACS‐1.
Hrs mediates downregulation of multiple signalling receptors in Drosophila
Authors: Jékely Gáspár , Rørth Pernille
Published: November 2003

Endocytosis and subsequent lysosomal degradation of activated signalling receptors can attenuate signalling. Endocytosis may also promote signalling by targeting receptors to specific compartments. A key step regulating the degradation of receptors is their ubiquitination. Hrs/Vps27p, an endosome‐associated, ubiquitin‐binding protein, affects sorting and degradation of receptors. Drosophila embryos mutant for hrs show elevated receptor tyrosine kinase (RTK) signalling. Hrs has also been proposed to act as a positive mediator of TGF‐β signalling. We find that Drosophila epithelial cells devoid of Hrs accumulate multiple signalling receptors in an endosomal compartment with high levels of ubiquitinated proteins: not only RTKs (EGFR and PVR) but also Notch and receptors for Hedgehog and Dpp (TGF‐β related). Hrs is not required for Dpp signalling. Instead, loss of Hrs increases Dpp signalling and the level of the type‐I receptor Thickveins (Tkv). Finally, most hrs‐dependent receptor turnover appears to be ligand independent. Thus, both active and inactive signalling receptors are targeted for degradation in vivo and Hrs is required for their removal.
The ubiquitin‐like protein HUB1 forms SDS‐resistant complexes with cellular proteins in the absence of ATP
Authors: Lüders Jens , Pyrowolakis George , Jentsch Stefan
Published: November 2003

Ubiquitin and ubiquitin‐like modifiers (UBLs) form covalent complexes with other proteins by isopeptide formation between their carboxyl (C)‐termini and ε‐amino groups of lysine residues of acceptor proteins. A hallmark of UBLs is a protruding C‐terminal tail with a terminal glycine residue, which is required for ATP‐dependent conjugation. Recently, the highly conserved protein HUB1 (homologous to ubiquitin 1) has been reported to function as a UBL following C‐terminal processing. HUB1 exhibits sequence similarity with ubiquitin but lacks a C‐terminal tail bearing a glycine residue. Here we show that HUB1 can form SDS‐resistant complexes with cellular proteins, but provide evidence that these adducts are not formed through covalent C‐terminal conjugation of HUB1 to substrates. The adducts are still formed when the C‐terminus of HUB1 was altered by epitope tagging, amino‐acid exchange or deletion, or when cells were depleted of ATP. We propose that HUB1 may act as a novel protein modulator through the formation of tight, possibly noncovalent interactions with target proteins.
Stunning and myocardial contractile autoregulation studied on the isolated isovolumic blood‐perfused dog heart
Authors: Tucci P. J. F. , Sant'Ana O. , Nogueira R. J. , Murad N. , Lopes A. C. , Sañudo A. , Peres C. A.
Published: November 2003

Aim:  To study, for the first time, the effects of stunning on homeometric and heterometric autoregulation.

Methods and results:  Ischaemia (15 min)/reperfusion (30 min) was induced in the isovolumic blood‐perfused dog heart preparation. Heart rate elevations (n = 9) from 60 to 200 beats min−1, in steps of 20 beats min−1, promoted the same inotropic stimulation in control (C) and stunning (S), indicating that ischaemia/reperfusion does not affect the changes in calcium kinetics elicited by the Bowditch effect. Sudden ventricular dilation (VD) (n = 10) evoked an instantaneous increase in developed pressure (Δ1DP) followed by a continuous slow performance increase (Δ2DP) in C and S. Δ1DP (C: 35 ± 2.2 mmHg; S: 27 ± 2.1 mmHg; P = 0.002) and Δ2DP (C: 20 ± 1.6 mmHg; S: 14 ± 1.3 mmHg; P = 0.002) decreased proportionally, while Δ2/Δ1DP (C: 0.57 ± 0.13; S: 0.58 ± 0.14) and slow response time course (T/2) were unchanged (C: 55 ± 6.6 s; S: 57 ± 7.7 s) after ischaemia/reperfusion. The reduction of Δ1DP can be understood as a decline of the myofilaments calcium responsiveness, the main pathophysiological effect of stunning. The reason for the weakening of Δ2DP, due to intracellular calcium gain, was not determined but it was supposed that its complete manifestation could be restricted by cyclic adenosine monophosphate (cAMP) myocardial content reduction. As reported by others, Δ2DP depends on myocardial cAMP, and it has been shown that myocardial cAMP is decreased after ischaemia/reperfusion.

Conclusions:  Contractile depression due to stunning has no effect on the inotropic stimulation generated by the Bowditch phenomenon. Immediate and time‐dependent enhancements of contraction evoked by sudden VD are proportionally reduced and the slow response time course is unaffected in the stunned myocardium.