269 research outputs found
Population dynamics of rodents and their parasite communities in a naturally fragmented landscape
An island system with corresponding mainland sites, was used to study
woodland rodent dynamics and their parasite communities within a naturally
fragmented landscape. The study site, hosts and parasite species investigated
within this thesis allowed the investigation of how natural fragmentation affects
demographic and population dynamics of rodents (chapter 3). Reduced habitat
connectivity is known to affect nearly every process in biology. Low degrees of
fragmentation and high connectivity between habitats have been shown to
provide the most stable conditions for populations to persist, as movement of
organisms is less restricted. It is shown that in contrast to previous studies on
fragmented populations, the fragmented landscape of the islands had little
effect on the demographic characteristics of rodent populations in comparison to
those on the mainland. There were few difference found in the demographics of
wood mice and bank voles when compared to mainland sites. The results from
this study then allowed the broader question of how parasites dynamics are
affected by the spatial structure of a host population to be addressed.
Theory predicts that parasites are unable to persist in small, isolated host
populations, due to small host population size as well as potential genetic
factors increasing the risk of extinction. However parasites may become more
prevalent in isolated populations as hosts may have a reduced ability to deal
with infection. It is shown (chapter 4) that within this study system that despite
some island populations being extremely small, there is no overall reduction in
parasite species found within fragmented habitats. Furthermore, extinction of
the parasites investigated within wood mice and bank voles is unlikely due to the
direct life cycle of these parasites. Variation was seen in the prevalence of
infection, however the majority of the parasite species on islands did not show a
reduced prevalence of infection compared to mainland sites.
Finally parasite co-infection and co-aggregation and their dependency on
host characteristics in woodland rodents (chapter 5) were investigated. Parasite
species infecting hosts are normally studied individually, however this is not
what is seen within natural populations. Co-infection is an important concept
within natural systems as there is a vast diversity of parasite species that create ample opportunity for concurrent infections. Therefore, it is proposed that
studies should be focused on parasite interactions, as within host interactions
can in turn affect the abundance and distribution at the level of the host
population. This study focused on seven parasite taxa, and it was found that the
maximum number of parasite species any individual was found to be infected
with was five, with the mean number for both host species at around two.
Parasites associations were also more common than expected within the same
functional groups with co-occurrence being more common between parasite
species associated with ectoparasites. Within this study, host aggregation was
positively correlated with differing parasite taxa. Furthermore, looking at
patterns of co-aggregation could aid in our understanding of parasite
interactions within hosts. The nature of these interactions will determine
whether aggregation is positively or negatively correlated across different
parasite taxa. A small number of hosts maybe responsible for transmitting the
majority of infections (20/80 rule). Identifying these individuals would be
informative in helping to control disease spread. Host characteristics have been
found to be informative in terms of single parasite species infections. Within this
study it was found that juvenile bank voles were more likely to be co-infected
than those within other age classes. No host characteristic explained patterns of
co-infection in wood mice.
In conclusion I found that natural fragmentation does not have an overall
negative effect on rodent host dynamics nor does it reduce the number or
prevalence of infection of parasite species able to infect hosts. This thesis has
highlighted the importance for using natural wildlife systems in empirical
studies, and the need to further address multiple parasite interactions within a
host community
Programme of the 21st European Conference on Eye Movements
About ECEM ECEM was initiated by Rudolf Groner (Bern), Dieter Heller (Bayreuth at the time) and Henk Breimer (Tilburg) in the 198 to provide a forum for an interdisciplinary group of scientists interested in eye movements. Since the inaugural meeting in Bern, the conference has been held every two years in different venues across Europe until 2021, when it was planned to take place in Leicester but was cancelled due to the COVID pandemic. It was decided to hold the meeting in Leicester in August 2022 instead, and as an in person meeting rather than an online or hybrid event. Incidentally, the present meeting is the third time the conference has come to the English East Midlands, now in Leicester following previous meetings in the neighbouring cities of Derby and Nottingham.
The sites of previous ECEMs and webpages can be found here
A further look at postview effects in reading: An eye-movements study of influences from the left of fixation
When reading from left to right, useful information acquired during each fixational pause is widely assumed to extend 14 to 15 characters to the right of fixation but just 3 to 4 characters to the left, and certainly no further than the beginning of the fixated word. However, this leftward extent is strikingly small and seems inconsistent with other aspects of reading performance and with the general horizontal symmetry of visual input. Accordingly, 2 experiments were conducted to examine the influence of text located to the left of fixation during each fixational pause using an eye-tracking paradigm in which invisible boundaries were created in sentence displays. Each boundary corresponded to the leftmost edge of each word so that, as each sentence was read, the normal letter content of text to the left of each fixated word was corrupted by letter replacements that were either visually similar or visually dissimilar to the originals. The proximity of corrupted text to the left of fixation was maintained at 1, 2, 3, or 4 words from the left boundary of each fixated word. In both experiments, relative to completely normal text, reading performance was impaired when each type of letter replacement was up to 2 words to the left of fixated words but letter replacements further from fixation produced no impairment. These findings suggest that key aspects of reading are influenced by information acquired during each fixational pause from much further leftward than is usually assumed. Some of the implications of these findings for reading are discussed
Fast and slow readers and the effectiveness of the spatial frequency content of text: Evidence from reading times and eye movements
© 2016 American Psychological Association. Text contains a range of different spatial frequencies but the effectiveness of spatial frequencies for normal variations in skilled adult reading ability is unknown. Accordingly, young skilled adult readers showing fast or slow reading ability read sentences displayed as normal or filtered to contain only very low, low, medium, high, or very high spatial frequencies. Reading times and eye movement measures of fixations and saccades assessed the effectiveness of these displays for reading. Reading times showed that, for each reading ability, medium, high, and very high spatial frequencies were all more effective than lower spatial frequencies. Indeed, for each reading ability, reading times for normal text were maintained when text contained only medium, high, or very high spatial frequencies. However, reading times for normal text and for each spatial frequency were all substantially shorter for fast readers than for slow readers, and this advantage for fast readers was similar for normal, medium, high, and very high spatial frequencies but much larger for low and very low spatial frequencies. In addition, fast readers made fewer and shorter fixations, fewer and shorter regressions, and longer forward saccades, than slow readers, and these differences were generally similar in size for normal, medium, high, and very high spatial frequencies, but larger when spatial frequencies were lower. These findings suggest that fast and slow adult readers can each use a range of different spatial frequencies for reading but fast readers make more effective use of these spatial frequencies and especially those that are lower
Effects of spatial frequencies on word identification by fast and slow readers: Evidence from eye movements
� 2016 Jordan, Dixon, McGowan, Kurtev and Paterson. Recent research has shown that differences in the effectiveness of spatial frequencies for fast and slow skilled adult readers may be an important component of differences in reading ability in the skilled adult reading population (Jordan et al., 2016a). But the precise nature of this influence on lexical processing during reading remains to be fully determined. Accordingly, to gain more insight into the use of spatial frequencies by skilled adult readers with fast and slow reading abilities, the present study looked at effects of spatial frequencies on the processing of specific target words in sentences. These target words were of either high or low lexical frequency and each sentence was displayed as normal or filtered to contain only very low, low, medium, high, or very high spatial frequencies. Eye movement behavior for target words was closest to normal for each reading ability when text was shown in medium or higher spatial frequency displays, although reading occurred for all spatial frequencies. Moreover, typical word frequency effects (the processing advantage for words with higher lexical frequencies) were observed for each reading ability across a broad range of spatial frequencies, indicating that many different spatial frequencies provide access to lexical representations during textual reading for both fast and slow skilled adult readers. Crucially, however, target word fixations were fewer and shorter for fast readers than for slow readers for all display types, and this advantage for fast readers appeared to be similar for normal, medium, high, and very high spatial frequencies but larger for low and very low spatial frequencies. Therefore, although fast and slow skilled adult readers can both use a broad range of spatial frequencies when reading, fast readers make more effective use of these spatial frequencies, and especially those that are lower, when processing the identities of words
Effects of word predictability on eye movements during Arabic reading
Contextual predictability influences both the probability and duration of eye fixations on words when reading Latinate alphabetic scripts like English and German. However, it is unknown whether word predictability influences eye movements in reading similarly for Semitic languages like Arabic, which are alphabetic languages with very different visual and linguistic characteristics. Such knowledge is nevertheless important for establishing the generality of mechanisms of eye-movement control across different alphabetic writing systems. Accordingly, we investigated word predictability effects in Arabic in two eye-movement experiments. Both produced shorter fixation times for words with high compared to low predictability, consistent with previous findings. Predictability did not influence skipping probabilities for (four- to eight-letter) words of varying length and morphological complexity (Experiment 1). However, it did for short (three- to four-letter) words with simpler structures (Experiment 2). We suggest that word-skipping is reduced, and affected less by contextual predictability, in Arabic compared to Latinate alphabetic reading, because of specific orthographic and morphological characteristics of the Arabic script
Cytology, culture and genomics to evaluate the microbiome in healthy rabbit external ear canals
Background: Lop-eared rabbits may be predisposed to otitis externa (OE) as a consequence of their ear conformation. Although otoscopy, otic cytological evaluation and culture are valuable tools in dogs and cats, published data on rabbits remain lacking. Hypothesis/Objectives: This study aimed to assess the utility of otoscopy and cytological results in evaluating healthy rabbit external ear canals (EECs) and to characterise ear cytological and microbiological findings through culture techniques and metagenomic sequencing. Animals: Sixty-three otitis-free client-owned rabbits. Materials and Methods: All rabbits underwent otoscopy and ear cytological evaluation. In a subset of 12 rabbits, further bacterial and fungal culture, fungal DNA assessment and metagenomic sequencing were performed. Results: Otic cytological results revealed yeast in 73%, cocci in 42.9% and rods in 28.6% of healthy rabbit EECs. Compared to upright-eared rabbits, lop-eared rabbits had more discharge and more bacteria per oil immersion field. Culture isolated eight different species yet metagenomic sequencing identified 36, belonging to the Bacillota (Firmicutes), Pseudomonadota and Actinomycetota phyla. Staphylococcus were the most commonly observed species with both methods. Ten of 12 rabbits were yeast-positive on cytological evaluation with only three yielding fungal growth identified as Yarrowia (Candida) lipolytica, Eurotium echinulatum and Cystofilobasidium infirmominiatum. Conclusions and Clinical Relevance: Healthy rabbit EECs lack inflammatory cells yet can host yeast and bacteria, emphasising the need to evaluate cytological results alongside the clinical signs. Lop-ear anatomy may predispose to bacterial overgrowth and OE. Notably, yeasts may be present despite a negative culture.</p
Five-year oncological outcomes after selective neoadjuvant radiotherapy for resectable rectal cancer
Effects of Normative Aging on Eye Movements during Reading
Substantial progress has been made in understanding the mostly detrimental effects of normative aging on eye movements during reading. This article provides a review of research on aging effects on eye movements during reading for different writing systems (i.e., alphabetic systems like English compared to non-alphabetic systems like Chinese), focused on appraising the importance of visual and cognitive factors, considering key methodological issues, and identifying vital questions that need to be addressed and topics for further investigation
- …