bluuebunny/crossref_metadata_2025 huggingface dataset:
Forage yield and persistency of Trifolium repens × Trifolium nigrescens hybrids under rotational sheep grazing
Authors: Marshall A. H. , Williams T. A. , Olyott P. , Abberton M. T. , Michaelson‐Yeates T. P. T.
Published: February 2005

Introgression of reproductive traits from the annual, profuse flowering, ball clover (Trifolium nigrescens Viv.) into white clover (Trifolium repens L.) is one breeding strategy to improve seed yields of T. repens that must be achieved without sacrificing agronomic performance and persistency under grazing. The yield and persistency of hybrids between white clover and T. nigrescens were compared under rotational sheep grazing over three harvest years. The hybrids included the backcross (BC) 2 and 3 generations produced using white clover as the recurrent parent. The large‐leaved T. repens variety Olwen, medium‐leaved varieties AberDai and Menna and the small‐leaved variety S184 were sown as controls. Hybrids and control varieties were sown with a perennial ryegrass companion; between April and the end of October in each harvest year the plots were rotationally grazed with sheep with clover and perennial ryegrass (DM) yield and the proportion of clover present measured over the growing season. The clover and total DM yields of the BC2 and BC3 were generally comparable with the small‐ and medium‐leaved varieties within the experiment and significantly greater than the yields of the large‐leaved variety Olwen. Throughout the 3 years of the experiment the BC2 maintained a clover content above 0·30 and comparable with the small‐leaved varieties, while the clover content of the BC3 was comparable with the small‐ and medium‐leaved varieties in the first and third harvest years. No significant difference in perennial ryegrass production was observed when grown with the backcrosses or the control varieties. Differences in stolon and growing‐point density were observed at the end of the experiment with the density of the BC2 and BC3 less than the small‐leaved variety S184 but, in common with the medium‐leaved varieties, greater than the large‐leaved variety Olwen. The implication of these results for the use of this material in future experiments and in the white clover breeding programme is discussed.
Transition through the taprooted growth stage in white clover as related to temperature
Authors: Bonesmo H. , Bakken A. K.
Published: February 2005

Morphology and phenology, including stolon disintegration, of white clover were studied at two sites in the first three years after sowing. The plants reached their maximum size in late summer in the first year after sowing, and the populations contained at that time mainly taprooted plants. The subsequent fragmented plants were smaller in most of the investigated characteristics. A function describing the daily transition rate from taprooted to fragmented plants in relation to daily mean temperature is presented. Deviations between the recorded and the calculated proportion of taprooted plants were small; the overall root mean square error was 0·057. The data indicated that there is a low temperature requirement that must be met prior to the onset of transition. It is also suggested that, in further modelling of the response of white clover to temperature, the effect of daylength should be accounted for, particularly if the data are collected from sites with a considerable latitudinal spread.
The productivity of oats and berseem clover intercrops. II. Effects of cutting date and density of oats on annual forage yield
Authors: Ross S. M. , King J. R. , O'Donovan J. T. , Spaner D.
Published: February 2005

Annual forage yields of intercrops of berseem clover (Trifolium alexandrinum L.) and oats (Avena sativa L.), as affected by timing of initial harvest and sowing rate of oats, were investigated. Berseem clover was intercropped with oats at 0, 30, 60, 90 and 240 plants m−2 of oats in 1999 and 2000 in Alberta, Canada. Cutting date treatments involved initial harvest at 10‐d intervals between 35 and 88 d after planting (DAP), and one or two subsequent harvests of regrowth. Total intercrop dry‐matter (DM) yield averaged 12·9–13·3 t ha−1 with proportions of 0·21–0·43 of berseem clover in the forage. Treatments with an initial cut at the silage stage of oats (76 DAP in 1999, 88 DAP in 2000, at about soft‐dough stage of oats) had greater yields of oats, lower yields of berseem clover, and lower proportions of berseem clover in total annual yields than treatments with an earlier initial cut. Total crude protein (CP) yield was greater with an initial cut at 65–66 DAP than with a silage‐stage initial cut. With an initial cut at 35 DAP (before stem elongation of oats) or after 65 DAP (after heading of oats), yield potential of oats was sometimes reduced compared with silage‐stage treatments, but this was balanced by a greater yield of berseem clover. The impact of harvest timing on total yield decreased as the proportion of berseem clover in the intercrops increased. With decreasing density of oats, DM yield of first‐cut intercrops and total DM yield of oats decreased, while regrowth and total DM yields of berseem clover increased. Intercrops with oats at 60 plants m−2 had equal or greater total DM and CP yields than intercrops with 240 plants m−2 of oats. For intercrops with oats at 60 plants m−2, with initial cuts at 65–66, 75–76, or 88 DAP, yields of regrowths were 0·30–0·35, 0·16–0·26 and 0·09 of the total yield respectively. Oats–berseem clover intercrops showed potential to manipulate the pattern of annual forage yield and to provide flexibility of harvest without reducing annual yields.
The productivity of oats and berseem clover intercrops. I. Primary growth characteristics and forage quality at four densities of oats
Authors: Ross S. M. , King J. R. , O'Donovan J. T. , Spaner D.
Published: February 2005

Berseem clover (Trifolium alexandrinum L.) was sown as an intercrop with oats (Avena sativa L.) at 0, 30, 60, 90 and 240 oats plants m−2 in May in 1999 and 2000 in Alberta, Canada. Forage yield and quality were measured at 10‐d intervals between 35 and 88 d after planting (DAP). Yield is defined as the biomass above 6 cm of the soil surface. The dry‐matter (DM) yield of berseem clover in sole crops increased by 5–10 g m−2 d−1 between 35 and 55 DAP and then increased by 21–28 g m−2 d−1 between 55 and 75 DAP. The DM yields of oats sown at 240 plants m−2 increased by 26–28 g m−2 d−1 over the whole period from 35 to 75 DAP. Oats were the dominant component in the intercrops, even at low densities of oats. Berseem clover grown with 60 oats plants m−2 received only 0·24 of the incident light when shading by oats peaked at 65 DAP. DM yields of berseem clover in intercrops with 60 oats plants m−2 averaged 0·14–0·32 of the yields of berseem clover sole crops. Between 35 and 88 DAP in 2000, the crude protein (CP) concentration of berseem clover sole crops declined linearly from 310 to 180 g kg−1 DM, and the CP concentration of oats exhibited a quadratic response, declining from 350 g kg−1 DM at tillering to 110 g kg−1 DM at the soft dough stage. The mean CP concentration of berseem clover in intercrops with 60 oats plants m−2 was 25 g kg−1 less than in berseem clover sole crops, indicating that competition by oats reduced the CP concentration of berseem clover. At later sampling dates, CP and DM yields of intercrops with oats at 60 plants m−2 equalled those with oats at 240 plants m−2. The addition of berseem clover to oats in intercrops at 60 oats plants m−2 reduced the neutral‐detergent fibre concentration by 30 g kg−1 DM compared with oats alone. Oats were very competitive as a companion crop for berseem clover. Adding berseem clover to oats increased forage quality and may provide for increased intake and digestibility of forage to support higher livestock productivity.
Are epiphytes important for birds in coffee plantations? An experimental assessment
Authors: CRUZ‐ANGÓN ANDREA , GREENBERG RUSSELL
Published: February 2005

Coffee is produced in tropical regions of the world, largely in Latin America. Coffee cultivation techniques range from traditional systems, where coffee grows under a diverse canopy of shade trees (shade‐coffee plantations), to modern systems, where coffee grows without any type of shade (sun‐coffee plantations). Shade‐coffee plantations provide refuge for forest fauna in otherwise deforested landscapes. The conservation value of these agro‐ecosystems depends upon their structural and floristic diversity.

The way coffee producers manage the vegetation, including the epiphytic component, may profoundly affect the value of plantations for conserving biological diversity. Shade‐coffee certification programmes have emerged to verify that coffee advertised as ‘shade grown’ is actually grown on highly biodiverse plantations. Although these programmes universally encourage epiphyte protection from pruning (a common practice), there has been no experimental evaluation of the importance of epiphytes in supporting faunal diversity. We report the effect of experimentally removing epiphytes on the bird assemblage in a shade‐coffee farm near Coatepec, Veracruz, Mexico.

We established two matching pairs of epiphyte removal and control plots. We compared bird diversity and abundance, based on daily censuses during the breeding and non‐breeding season. We used existing information on the way in which birds use epiphytes as foraging and nesting substrates to explain the presence of different species in plots with epiphytes.

Plots without epiphytes tended to be less diverse than plots with epiphytes, but rarefaction analysis and anova showed no significant differences in species richness between treatments in any of the seasons. Mean bird abundance was significantly higher in plots with epiphytes during both seasons, and a multidimensional scaling analysis showed that bird community structure differed between the two treatments.

Eighteen forest bird species were significantly more abundant in plots with epiphytes. Three non‐forest species were more common in plots without epiphytes. Resident bird species that used epiphytes as a nesting substrate were significantly more abundant in plots with epiphytes.

When epiphytes are removed, canopy cover, foraging substrates, nest sites and nest materials are eliminated and microclimatic conditions change. This could increase predation on adult birds and nests, increase intra‐ and interspecific competition, and decrease individual survivorship.

Synthesis and applications. This is the first experimental assessment of the importance of epiphytes for birds. Shade‐coffee plantations with epiphytes maintain higher abundance and diversity of the inhabitant bird fauna than plantations without epiphytes. This study reinforces the value of positive epiphyte management as an important factor in shade‐grown coffee certification, where the goal is to promote biodiversity conservation.
Non‐random species extinction and plant production: implications for ecosystem functioning
Authors: SCHLÄPFER F. , PFISTERER A. B. , SCHMID B.
Published: February 2005

Understanding ecosystem responses to plant species loss is essential for the optimal management of grasslands. Recent studies have examined the effects of simulated random species loss in experimental plant communities but not those of realistic non‐random species loss resulting from transient extinction pressures in semi‐natural grasslands.

To investigate the potential effects of non‐random species loss on grassland productivity, we established mesocosms with mixed communities comprising 15 plant species, and exposed them to 2 years of high‐intensity management (an extinction phase) followed by 2 years of low‐intensity management (a restoration phase) allowing recolonization from differentially managed neighbouring plots. In addition, monocultures of each component species were subject to the same extinction–restoration phases.

During the extinction phase, species with high monoculture biomass had lower extinction probabilities in the mixed community than species with low monoculture biomass, but there was also species‐specific variation. The species that were most productive or most persistent during the extinction phase were not the same as those performing best in the restoration phase.

No consistent effects of spontaneous recolonization from neighbouring communities on species richness or productivity of the focal communities were observed during the restoration phase.

We estimated that extinction of all but the species with the lowest extinction risk reduced biomass productivity by 42–49%; loss of all but the four species with the lowest extinction risk reduced it by 2–35%. Identical calculations for a random extinction scenario yielded reductions of 52% and 26–54%, respectively.

Synthesis and applications. Prediction of the effects of species loss on plant production and on other aspects of ecosystem functioning in semi‐natural grasslands must account for both specific non‐random extinction processes and post‐extinction conditions. For European mesic grasslands experiencing a shift from high‐intensity to low‐intensity management, our results suggest that recolonization by ‘missing’ species must be actively assisted if high production is a management objective.
Effects of timing of prescribed fire on the demography of an invasive plant, spotted knapweed Centaurea maculosa
Authors: EMERY SARAH M. , GROSS KATHERINE L.
Published: February 2005

Prescribed burning is a key tool used in prairie and savanna restoration projects. The timing and frequency of prescribed fires are important variables to consider because they can differentially affect the survival of individual plant species, including noxious exotic species.

We used annual censuses and population matrix analysis to evaluate the demographic consequences of burning on populations of the invasive species spotted knapweed Centaurea maculosa in a Michigan, USA, prairie restoration experiment. We compared spring, summer and autumn burns at two frequencies: annually (2000–03) and in alternate years (2001, 2003). We examined the effects of different seasons and frequencies of prescribed fire on the survival, growth and reproduction of C. maculosa populations, and used life‐table response experiments and elasticity analyses to determine how season of fire affects population growth rates.

We found that annual summer burning was the only treatment that significantly reduced overall population growth rates.

The life‐table response experiment analysis indicated which life stages contributed the most to changes in population growth rates under the different treatments. The summer burn treatments reduced population growth by reducing reproduction.

The different burn treatments altered the elasticity structure of populations, but in general reproduction of adults as well as survival of non‐reproductive adults and juveniles remained important in all treatments. This indicates that future attempts to control C. maculosa should focus on combinations of treatments targeting these life stages.

Synthesis and applications. Management decisions regarding prescribed burning in grassland restoration projects should consider the responses of individual species already present in the system. In particular, it is important to consider the effects of burning on noxious invasive species that may or may not have different life histories and responses to fire compared with native species. Population matrix modelling provides a more complete picture of the effects of management on population responses compared with other measures based only on community composition and relative abundance. Depending on the goals of a restoration, non‐traditional management options, such as summer burning in mid‐west USA prairies, may be effective management tools for the control of invasive species.
Vegetation–site relationships of roadside plant communities in West Virginia, USA
Authors: RENTCH J. S. , FORTNEY R. H. , STEPHENSON S. L. , ADAMS H. S. , GRAFTON W. N. , ANDERSON J. T.
Published: February 2005

In mountainous regions, road construction is accompanied by large‐scale physical disturbance associated with cut and fill operations that drastically alter the landscape. Cut operations remove soil and rock from the hillside above the proposed road, while soil and rock are deposited on the down‐slope area in fill operations. The resultant roadsides are highly disturbed habitats characterized by plant communities maintained at an early successional stage. They are often planted with non‐native species and frequently provide vectors for the introduction and spread of invasive species. Public transportation managers need to balance the rapid revegetation of roadsides with the goal of maximizing use of native species and minimizing the introduction of non‐native species.

This study examined vegetation–site relationships along 13 major four‐lane highways in West Virginia, USA, using analysis of variance, multiresponse permutation procedures and indicator species analysis.

Mean soil nutrient values showed some differences with respect to highway, but fewer when highway positions were compared. Similarly, when highway position was considered, there were no significant differences in mean plant species richness, evenness or diversity.

Results of multiresponse permutation procedures suggested that different highways may be characterized by distinct vegetation assemblages. This hypothesis was supported by indicator species analysis: 54 species showed a statistically significant (P < 0·05) affinity to one highway over all others. More than half of these were classified as non‐native and exotic invasive species. When highway position was considered, no significant differences in community composition were found, and indicator species analysis found only 25 species that exhibited a significant affinity to one type of position. Of these, only eight were exotic.

Of the 33 most abundant herbaceous species, 11 showed a significant relationship between cover and distance from pavement. For all but one, average cover declined in a linear fashion with increasing distance.

Synthesis and applications. Despite extensive topographic disturbance associated with highway construction, the resultant vegetative communities do not differ with respect to type of construction or resultant landform. This suggests that highway agencies can manage roadside vegetation using similar, standard techniques. Roadsides are optimal growing sites for exotic invasive species that out‐compete native vegetation. Management goals should therefore include techniques for limiting the establishment of these species, and substitution of non‐native species planted for erosion control with suitable native species.
Stable coexistence of an invasive plant and biocontrol agent: a parameterized coupled plant–herbivore model
Authors: BUCKLEY YVONNE M. , REES MARK , SHEPPARD ANDREW W. , SMYTH MATTHEW J.
Published: February 2005

Coupled plant–herbivore models, allowing feedback from plant to herbivore populations and vice versa, enable us to predict the impact of biocontrol agents on their target weed populations; however, they are rarely used in biocontrol studies. We describe the population biology of the invasive plant Echium plantagineum and the weevil Mogulones larvatus, a biocontrol agent, in Australia. In order to understand the dynamics of this plant–herbivore system, a series of coupled models of increasing complexity was developed.

A simple model was extended to include a seed bank, density‐dependent plant fecundity, competition between weevil larvae and plant tolerance of herbivory, where below a threshold plants could compensate for larval feeding. Parameters and functional forms were estimated from experimental and field data.

The plant model, in the absence of the weevil, exhibited stable dynamics and provided a good quantitative description of field densities before the weevil was introduced.

In the coupled plant–herbivore model, density dependence in both plant fecundity and weevil larval competition stabilized the dynamics. Without larval competition the model was unstable, and plant tolerance of herbivory exacerbated this instability. This was a result of a time delay in plant response to herbivore densities.

Synthesis and applications. The coupled plant–herbivore model allowed us to predict whether stable coexistence of target plant and biocontrol agents was achievable at an acceptable level. We found this to be the case for the Echium–Mogulones system and believe that similar models would be of use when assessing new agents in this and other invasive plant biocontrol systems. Density dependence in new biocontrol agents should be assessed in order to determine whether it is likely to result in the aims of classical biocontrol: low, stable and sustainable populations of plant and herbivore. Further work should be done to characterize the strength of density dependence according to the niche occupied by the biocontrol agent, for example the strength and functional form of density dependence in stem borers may be quite different to that of defoliators.
Exposure of non‐target small mammals to rodenticides: short‐term effects, recovery and implications for secondary poisoning
Authors: BRAKES C. R. , SMITH R. H.
Published: February 2005

Monitoring of exposure to pesticides in many countries shows extensive exposure of predators to anticoagulant rodenticides, which are used to control rats. Many predators and scavengers are declining in numbers, and exposure to rodenticides might therefore be of importance in conservation biology.

Predators and scavengers of poisoned rats are at most risk of secondary poisoning. However, several predatory species of conservation concern rarely eat rats, implicating non‐target small mammals as the major route of exposure. For the first time, this research investigated the importance of non‐target small mammals as routes of exposure to rodenticide for predators and scavengers in the UK.

Exposure studies of non‐target small mammals were carried out alongside routine rat control at five sites, around agricultural buildings (n = 2) and feed hoppers for game birds (n = 3).

Three non‐target rodent species fed on rodenticide from bait boxes during routine rat control treatments. A large proportion (48·6%) of individuals in local populations ate the bait: woodmice Apodemus sylvaticus were most exposed, followed by bank voles Clethrionomys glareolus then field voles Microtus agrestis.

Local populations of non‐target small mammals declined significantly following rodenticidal rat control but their relative proportions did not change significantly. Populations recovered partially after 3 months, depending on the time of the year relative to the breeding cycle.

Synthesis and applications. Our results clearly demonstrate that routine rat control reduced local populations of non‐target small mammals. This may limit the food supply of some specialist predators. Most importantly, this demonstrates a significant route of exposure of predators and scavengers of small mammals to secondary poisoning. Rodenticides are applied on farms and game estates across the UK. Hence the results of this study are indicative of non‐target rodenticide exposure nationally. Mitigation requires a shift from the current reliance on rodenticides to ecologically based rodent management, involving improvements in site management and the adoption of good farming practice.
Indirect negative impacts of radio‐collaring: sex ratio variation in water voles
Authors: MOORHOUSE TOM P. , MACDONALD DAVID W.
Published: February 2005

Radio‐tracking is used ubiquitously in studies of wild vertebrates, a fundamental assumption being that tagged animals do not significantly differ, behaviourally or otherwise, from untagged animals.

We studied two populations of water volesArvicola terrestris: one population was live‐trapped from April to September for 2 years (2000, 2001) and then concurrently radio‐tracked and trapped in a third year (2002). The second population was trapped only during 2002.

During 2002, a substantial decline in female numbers in the radio‐collared population was recorded, apparently resulting from a male skew in the sex ratios of offspring born to this population. The mean numbers of males and females born duringtrappingonly were 25·7 (SD 2·1) and 29·0 (SD 7·0), respectively. Recruits to theradio‐trackedpopulation were skewed heavily in favour of males (43 : 13).

Both hypotheses commonly invoked to explain mammalian sex‐ratio manipulation refer to the condition of mothers. The altered sex ratio resulted from a 48% decrease in numbers of females born, a decrease similar to the proportion (0·49) of the female population that was collared. No similar decline in male births occurred. This suggests that radio‐collaring of females caused male‐skewed sex ratios.

Synthesis and applications. We conclude that the observed decline in female numbers resulted from male‐skewed recruitment sex ratios due to the attachment of radio‐collars to female water voles. These results question the assumption that the use of radio‐collars does not fundamentally affect the biology of collared water voles.
Predicting numbers of hauled‐out harbour seals: a mathematical model
Authors: HAYWARD JAMES L. , HENSON SHANDELLE M. , LOGAN CLARA J. , PARRIS CATHERINE R. , MEYER MATTHEW W. , DENNIS BRIAN
Published: February 2005

It was once assumed that commercially important fish make up significant portions of seal diets. As a consequence, prior to the 1970s many seal populations were dramatically reduced by rampant slaughtering. Today, seals and other marine mammals are valued components of marine ecosystems and their numbers are carefully managed. To facilitate management, government statutes mandate the systematic monitoring of seal populations. Population estimates are based on counts of hauled‐out seals obtained by aerial survey and radio and satellite telemetry; hence, considerable effort has been devoted to finding optimal times for such counts. We have developed a predictive mathematical model of seal haul‐out to assist resource managers in the selection of optimal census times.

Haul‐out depends on a number of environmental variables. Some of these variables, such as wind speed, can be obtained only as historical data or short‐range predictions. Others, such as tide height, are deterministic and can be obtained as long‐range predictions.

We used deterministic environmental variables to develop mathematical models that describe haul‐out dynamics of harbour sealsPhoca vitulinaduring the pupping season at a site in Washington, USA. A list of alternative hypotheses for environmental cues gave rise to a suite of competing models. We used information–theoretic model selection techniques to choose the best model. The selected model was a function of tide height and current direction, and explained 40% of the variability in hourly census data.

An assumption that the system recovers rapidly after disturbance introduced two time scales. This allowed the differential equation model to be reduced to an algebraic equation.

Synthesis and applications.This study demonstrates that resource managers can use a simple algebraic equation based on deterministic environmental variables to predict times at which to census maximal haul‐out in harbour seals. At the Washington site, maximal daily haul‐outs during pupping season are predicted to occur during receding tides, approximately midway between high and low tides. The largest maximal daily haul‐outs during the pupping season are predicted to occur in the last week of July. The environmental factors correlated with haul‐out are, however, site‐specific; therefore the model developed for the Washington site will not necessarily hold for other haul‐out areas. Managers should carry out the model selection procedure separately for each monitored haul‐out site. The general methodology employed in this study can be used to make long‐range predictions of diurnal movements for a variety of marine birds and mammals.
Power of monitoring programmes to detect decline and recovery of rare and vulnerable fish
Authors: MAXWELL DAVID , JENNINGS SIMON
Published: February 2005

Abundance trends provide key guidance when setting conservation priorities, whether indicating population decline, stability or recovery. Knowledge of the power of surveys to detect trends is essential, as the consequences of not detecting a real trend can be profound.

Unfortunately, some surveys have been established with no assessment of power, and others are used to study species that were not their original focus. The latter is common in the marine environment, where rare fish are monitored using catch data from surveys that target more abundant commercially fished species.

We calculated the power of a large‐scale annual monitoring survey (the English North Sea bottom trawl survey) to detect decline and recovery of species that are vulnerable to fishing. As fisheries exploitation invariably precedes scientific investigation, the survey began after many vulnerable species had already been depleted.

The power of the survey to detect declines in the abundance of vulnerable species on time scales of < 10 years was low and the survey often failed to detect declines that would lead to listings under the IUCN A1 Red List criteria. Thus conservation prioritization based solely on survey data may fail to identify species at risk of regional extinction.

If conservation measures were effective, and vulnerable populations recovered at the maximum potential rate, 5–10 years of monitoring would often be required to detect recovery.

Power to detect trends in abundance was increased by developing a composite indicator that reflected trends in abundance of several vulnerable species. This indicator provided an overview of their conservation status.

Synthesis and applications. Consistent with the precautionary principle, conservation prioritization and management action should not depend on the statistical significance of recent abundance trends when low power is a consequence of historical depletion. If the conservation prioritization and management of rare and/or vulnerable species have to be predicated on evidence of significant declines, then higher type 1 error rates (falsely detecting a decline) should be acceptable. This is because the costs of type 1 errors are lower than those of type 2 (failure to detect a real decline).
Information theory and hypothesis testing: a call for pluralism
Authors: STEPHENS PHILIP A. , BUSKIRK STEVEN W. , HAYWARD GREGORY D. , MARTÍNEZ DEL RIO CARLOS
Published: February 2005

A major paradigm shift is occurring in the approach of ecologists to statistical analysis. The use of the traditional approach of null‐hypothesis testing has been questioned and an alternative, model selection by information–theoretic methods, has been strongly promoted and is now widely used. For certain types of analysis, information–theoretic approaches offer powerful and compelling advantages over null‐hypothesis testing.

The benefits of information–theoretic methods are often framed as criticisms of null‐hypothesis testing. We argue that many of these criticisms are neither irremediable nor always fair. Many are criticisms of the paradigm's application, rather than of its formulation. Information–theoretic methods are equally vulnerable to many such misuses. Care must be taken in the use of either approach but users of null‐hypothesis tests, in particular, must greatly improve standards of reporting and interpretation.

Recent critiques have suggested that the distinction between experimental and observational studies defines the limits of the utility of null‐hypothesis testing (with the paradigm being applicable to the former but not the latter). However, we believe that there are many situations in which observational data are collected that lend themselves to analysis under the null‐hypothesis testing paradigm. We suggest that the applicability of the two analytical paradigms is more accurately defined by studies that assess univariate causality (when null‐hypothesis testing is adequate) and those that assess multivariate patterns of causality (when information–theoretic methods are more suitable).

Synthesis and applications. Many ecologists are confused about the circumstances under which different inferential paradigms might apply. We address some of the major criticisms of the null‐hypothesis testing paradigm, assess those criticisms in relation to the information–theoretic paradigm, propose methods for improving the use of null‐hypothesis testing, and discuss situations in which the use of null‐hypothesis testing would be appropriate. We urge instructors and practitioners of statistical methods to heighten awareness of the limitations of null‐hypothesis testing and to use information–theoretic methods whenever prior evidence suggests that multiple research hypotheses are plausible. We contend, however, that by marginalizing the use of null‐hypothesis testing, ecologists risk rejecting a powerful, informative and well‐established analytical tool.
Simple optimization procedure for objective lens correction collar setting
Authors: SCHWERTNER M. , BOOTH M. J. , WILSON T.
Published: February 2005

We present a new method for setting a coverglass correction collar on an objective lens. Axial scans across the interface between the specimen volume and the slide are used together with a quantitative function of merit to determine the optimum setting of the correction collar. The method, which simplifies the adjustment for the user and reduces photobleaching, was implemented within the software environment of a scanning microscope system.
Two‐photon excitation and emission spectra of the green fluorescent protein variants ECFP, EGFP and EYFP
Authors: SPIESS E. , BESTVATER F. , HECKEL‐POMPEY A. , TOTH K. , HACKER M. , STOBRAWA G. , FEURER T. , WOTZLAW C. , BERCHNER‐PFANNSCHMIDT U. , PORWOL T. , ACKER H.
Published: February 2005

Two‐photon (TP) excitation (820–1150 nm) and emission (280–700 nm) spectra for the fluorescent proteins (FPs) ECFP3, EGFP3 and EYFP3 produced in human tumour cells were recorded. TP excitation spectra of pure and highly enriched samples were found to be more differentiated in comparison with their one‐photon (OP) spectra. They exhibited more pronounced main and local maxima, which coincided among different purity grades within small limits. TP and OP emission spectra of pure and enriched samples were identical. However, in crude samples, excitation was slightly blue‐shifted and emission red‐shifted. The data indicate that both OP and TP excitation routes led to the same excited states of these molecules. The emission intensity is dependent on the pH of the environment for both types of excitation; the emission intensity maximum can be recorded in the alkaline range. Reconstitution of emission intensity after pH quenching was incomplete, albeit that the respective spectral profiles were identical to those prequenching. When emission data were averaged over the whole range of excitation, the resulting emission profile and maximum coincided with the data generated by optimal excitation. Therefore, out‐of‐maximum excitation, common practice in TP excitation microscopy, can be used for routine application.
Two‐photon excitation fluorescence pH detection using 2,3‐dicyanohydroquinone: a spectral ratiometric approach
Authors: JÖBSIS P. D. , COMBS C. A. , BALABAN R. S.
Published: February 2005

The use of 2,3‐dicyanohydroquinone (DCHQ) as an emission ratiometric probe of pH in vitro and in fibroblast cells was evaluated using two‐photon excitation fluorescence microscopy (TPEFM). In addition, methods for spectrally calibrating the Zeiss LSM510 META spectroscopy system for TPEFM were also developed. The emissions of both the acid and base forms of DCHQ were detectable when using an 800‐nm excitation in TPEFM, thereby allowing ratiometric determination of pH. These data suggest that, in contrast to most other emission ratiometric probes, both acid and base forms of DCHQ have similar two‐photon cross‐sectional areas at 800 nm. Acid (maximum at ∼457 nm) and base (maximum at ∼489 nm) DCHQ TPEFM emission spectra were similar to previously reported one‐photon excitation emission spectra. Calibration curves for pH were successfully constructed using the ratio of DCHQ emission difference maxima at 460 nm and 512 nm in vitro and in cells. To our knowledge, DCHQ is currently the only effective emission ratiometric pH indicator for two‐photon microscopy and may serve as a useful starting point for the development of other TPEFM ratiometric dyes for quantitative measurement of other cell parameters such as Ca2+, Mg2+ or Na+.
Third‐order aberration theory of Wien filters for monochromators and aberration correctors
Authors: TSUNO K. , IOANOVICIU D. , MARTÍNEZ G.
Published: February 2005

Third‐order aberrations at the first and the second focus planes of double focus Wien filters are derived in terms of the following electric and magnetic field components – dipole: E1, B1; quadrupole: E2, B2; hexapole: E3, B3 and octupole: E4, B4. The aberration coefficients are expressed under the second‐order geometrical aberration free conditions of E2 = −(m + 2)E1/8R, B2 = −mB1/8R and E3R2/E1 − B3R2/B1 = m/16, where m is an arbitrary value common to all equations. Aberration figures under the conditions of zero x‐ and y‐axes values show very small probe size and similar patterns to those obtained using a previous numerical simulation [G. Martínez & K. Tsuno (2004) Ultramicroscopy, 100, 105–114]. Round beam conditions are obtained when B3 = 5m2B1/144R2 and (E4/E1 − B4/B1)R3 = −29m2/1152. In this special case, aberration figures contain only chromatic and aperture aberrations at the second focus. The chromatic aberrations become zero when m = 2 and aperture aberrations become zero when m = 1.101 and 10.899 at the second focus. Negative chromatic aberrations are obtained when m < 2 and negative aperture aberrations for m < 1.101. The Wien filter functions not only as a monochromator but also as a corrector of both chromatic and aperture aberrations. There are two advantages in using a Wien filter aberration corrector. First, there is the simplicity that derives from it being a single component aberration correction system. Secondly, the aberration in the off‐axis region varies very little from the on‐axis figures. These characteristics make the corrector very easy to operate.
A simple method allowing DIC imaging in conjunction with confocal microscopy
Authors: CODY S. H. , XIANG S. D. , LAYTON M. J. , HANDMAN E. , LAM M. H. C. , LAYTON J. E. , NICE E. C. , HEATH J. K.
Published: February 2005

Current optical methods to collect Nomarski differential interference contrast (DIC) or phase images with a transmitted light detector (TLD) in conjunction with confocal laser scanning microscopy (CLSM) can be technically challenging and inefficient. We describe for the first time a simple method that combines the use of the commercial product QPm (Iatia, Melbourne Australia) with brightfield images collected with the TLD of a CLSM, generating DIC, phase, Zernike phase, dark‐field or Hoffman modulation contrast images. The brightfield images may be collected at the same time as the confocal images. This method also allows the calculation of contrast‐enhanced images from archival data. The technique described here allows for the creation of contrast‐enhanced images such as DIC or phase, without compromising the intensity or quality of confocal images collected simultaneously. Provided the confocal microscope is equipped with a motorized z‐drive and a TLD, no hardware or optical modifications are required. The contrast‐enhanced images are calculated with software using the quantitative phase‐amplitude microscopy technique (Barone‐Nugent et al., 2002). This technique, being far simpler during image collection, allows the microscopist to concentrate on their confocal imaging and experimental procedures. Unlike conventional DIC, this technique may be used to calculate DIC images when cells are imaged through plastic, and without the use of expensive strain‐free objective lenses.
Structural characterization of TiN/NbN multilayers: X‐ray diffraction, energy‐filtered TEM and Fresnel contrast techniques compared
Authors: LLOYD S. J. , MOLINA‐ALDAREGUIA J. M. , CLEGG W. J.
Published: February 2005

Two TiN/NbN multilayers with wavelength 13.6 and 6.15 nm have been characterized by X‐ray diffraction (XRD), Fresnel contrast analysis (FCA) and energy‐filtered transmission electron microscopy (EFTEM). Good agreement between the composition profile obtained by FCA and EFTEM is obtained if the lower resolution of the EFTEM images is taken into account. The relative advantages and disadvantages of the techniques are discussed. Used together the two TEM techniques provide a quantitative characterization that is consistent with, and for some parameters provides more precise values than, that from XRD. The analysis shows that the multilayers have narrow interfaces (< 1 nm) and a composition amplitude close to 95% for the longer wavelength.
Loss of expression of E‐cadherin and β‐catenin is associated with progression of pulmonary adenocarcinoma
Authors: Awaya Hirokazu , Takeshima Yukio , Amatya Vishwa Jeet , Ishida Hajime , Yamasaki Masahiro , Kohno Nobuoki , Inai Kouki
Published: February 2005

The aim of the present study was to determine the association of loss of membranous expression of epithelial (E)‐cadherin and β‐catenin with the progression of pulmonary adenocarcinoma. The expression of E‐cadherin and β‐catenin was examined in 154 cases of pulmonary adenocarcinoma, including 49 cases of atypical adenomatous hyperplasia (AAH), 40 cases of bronchioloalveolar carcinoma (BAC), 42 cases of BAC‐dominant type of adenocarcinoma with mixed subtypes (early MX) and 23 cases of BAC‐recessive type of adenocarcinoma with mixed subtypes (overt MX), by immunohistochemistry. E‐cadherin expression was positive in all cases of AAH, in 37 cases (92.5%) of BAC and in 34 cases (81.0%) of early MX, while it was positive in three cases (13.0%) of overt MX. β‐Catenin expression was positive in 47 cases (95.9%) of AAH, in 28 cases (70%) of BAC, in 32 cases (76.2%) of early MX and in 11 cases (47.8%) of overt MX. The rates of expression of E‐cadherin and β‐catenin among cases of AAH, BAC, early MX and overt MX were significantly reduced. Loss of expression of E‐cadherin and β‐catenin may play an important role in the progression of pulmonary adenocarcinoma, and these events occur before structural destruction of the alveolar wall by invasion of carcinoma cell.
Autopsy case of CD4–/CD8– cutaneous T‐cell lymphoma presenting disseminated pagetoid reticulosis with aggressive granulomatous invasion to the lungs and pancreas
Authors: Shiozawa Eisuke , Shiokawa Akira , Shibata Mari , Nakada Tokio , Yamochi‐Onizuka Toshiko , Saito Bungo , Takaba Emi , Iijima Masafumi , Takimoto Masafumi , Ota Hidekazu
Published: February 2005

Pagetoid reticulosis is a rare cutaneous T‐cell lymphoma with striking epidermotropism similar to that present in Paget's disease. There are two forms of pagetoid reticulosis: localized and disseminated. Reported herein is an autopsy case of disseminated pagetoid reticulosis with CD4–/CD8– phenotype T cells and massive invasion of the lungs and pancreas. The abnormal cells in the epidermis expressed a protein derived from a rearranged T‐cell receptor β gene, and this feature was used to confirm the monoclonality of these cells by polymerase chain reaction. At present, the World Health Organization (WHO) classification system considers pagetoid reticulosis to be an indolent form of primary cutaneous T‐cell lymphoma and a variant of mycosis fungoides/Sézary syndrome with prominent epidermotropism. Some differences have been observed between pagetoid reticulosis and mycosis fungoides in terms of clinical course, tumor cell phenotype, and genetic findings; and these differences are highlighted in the present case. The relation between disseminated pagetoid reticulosis,  CD4–/CD8–  cutaneous  T‐cell  lymphoma,  and γδ  T‐cell lymphoma, including whether pagetoid reticulosis is a variant of mycosis fungoides, remains unclear.
Adequacy of outpatient management of asthma patients admitted to a state hospital in Argentina
Authors: RAIMONDI Guillermo A. , MENGA Guillermo , RIZZO Oscar , MERCURIO Sandra
Published: February 2005

Objective:  The aim of this study was to assess chronic outpatient management of adult patients admitted with asthma.

Methodology:  A cross‐sectional survey was conducted of 98 consecutive asthma admissions to a specialized pulmonary State Hospital in Buenos Aires, Argentina, over a 12‐month period. Patients were surveyed, within 48 h of admission, with a previously validated questionnaire which deals with chronic outpatient management and measures taken by patients or physicians to treat symptoms during asthma exacerbations.

Results:  FEV1% predicted was 30.2 ± 10.7. Mean admission rate and emergency department (ED) visits in the previous year were 0.7 ± 1.2 and 4.6 ± 5.1, respectively. A total of 96, 65 and 9% of the patients had been treated previously in the ED, admitted to hospital or mechanically ventilated, respectively. Only 62% had been prescribed inhaled corticosteroids (IC) by their physician; 38% had been prescribed nebulized beta agonists (Nβ2) and 68% a metered dose inhaler (MDIβ2). Inhaled β2‐agonist usage during acute exacerbations over the 24 h prior to admission was 14.4 ± 7.4 puffs for MDIβ2 and 8.6 ± 5.4 occasions for Nβ2. Only 11% of the patients were able to perform all the steps of the MDI inhalation technique correctly. An action plan had been provided by their physicians to 43% of patients, while 58% changed their medication on their own. Only three patients had a peak flow meter (PFM) prescribed. ED was used by 26% for their routine care. No health insurance coverage was available to 75.5% of the patients.

Conclusions:  Underuse of IC, poor MDI inhalation technique, and low prescription of an action plan was common and a PFM was seldom prescribed. During exacerbations, many patients changed their medication spontaneously and MDIβ2 underuse was observed.
The effect of a post acute respiratory outreach service for patients with chronic obstructive pulmonary disease on hospital readmission rates
Authors: JEFFS Kimberley J. , LIM Wen K. , LIM Michael , BERLOWITZ David J. , JACKSON Bruce
Published: February 2005

Objective:  The aim of this study was to investigate the effect of a Post Acute Respiratory Outreach Service (PAROS) for patients with chronic obstructive pulmonary disease (COPD), on hospital utilization.

Methods:  A retrospective cohort of patients was examined, using a nested comparison, to test the hypothesis that PAROS would affect hospital utilization in the 12 months following the intervention. Patients admitted with COPD and subsequently enrolled in PAROS were compared with age, sex and diagnosis‐matched controls admitted with COPD, who did not receive PAROS.

Results:  Of 216 patients admitted with COPD during the 1‐year study period, 28 were referred to PAROS. A total of 25 suitable controls were identified. Three cases that could not be matched were excluded from the analysis. There were no significant differences in lung function or prior hospitalization between the two groups at baseline. A significant increase in hospital bed days, in the 12 months following the index admission, was observed in the PAROS group (P = 0.046). There was no difference in the number of admissions or emergency department presentations between the groups.

Conclusions:  The PAROS program did not lead to a reduction in hospital utilization. This study supports previous findings that respiratory outreach services delivered immediately post discharge increase hospital utilization.