523 research outputs found
Perceptual belongingness and spatial propagation of lightness contrast
No full textAgostini and Proffitt (1993) showed that perceptual belongingness can cause simultaneous lightness contrast (SLC) to be seen in configurations where the inducing elements are not adjacent to the target. In some observations, in Agostini and Proffitt-type configurations, we showed that belongingness determines SLC also when the numbers of inducing elements is drastically reduced, and that the induction effect spatially propagates on all the unified elements
The Mass of the Cepheid V350 Sgr
No full textV350 Sgr is a classical Cepheid suitable for mass determination. It has a hot companion which is prominent in the ultraviolet (UV) and which is not itself a binary. We have obtained two high-resolution echelle spectra of the companion at orbital velocity maximum and minimum with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope in the 1320 to 1510a region. By cross-correlating these spectra we obtained the orbital velocity amplitude of the companion with an uncertainty in the companion amplitude of 1.9 km s-1. This provides a mass ratio of the Cepheid to the companion of 2.1. The UV energy distribution of the companion provides the mass of the companion, yielding a Cepheid mass of 5.2 ±0.3 M o. This mass requires some combination of moderate main sequence core convective overshoot and rotation to match evolutionary tracks
Welcome to Wonderland : the influence of the size and shape of a virtual hand on the perceived size and shape of virtual objects
No full textThe notion of body-based scaling suggests that our body and its action capabilities are used to scale the spatial layout of the environment. Here we present four studies supporting this perspective by showing that the hand acts as a metric which individuals use to scale the apparent sizes of objects in the environment. However to test this, one must be able to manipulate the size and/or dimensions of the perceiver’s hand which is difficult in the real world due to impliability of hand dimensions. To overcome this limitation, we used virtual reality to manipulate dimensions of participants’ fully-tracked, virtual hands to investigate its influence on the perceived size and shape of virtual objects. In a series of experiments, using several measures, we show that individuals’ estimations of the sizes of virtual objects differ depending on the size of their virtual hand in the direction consistent with the body-based scaling hypothesis. Additionally, we found that these effects were specific to participants’ virtual hands rather than another avatar’s hands or a salient familiar-sized object. While these studies provide support for a body-based approach to the scaling of the spatial layout, they also demonstrate the influence of virtual bodies on perception of virtual environments
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Survival and growth of juvenile hatchery-reared spotted seatrout, cynoscion nebulosus, stocked into rearing ponds at 2 and 9 days post-hatch
No full textOf concern to recreational fisheries is the growth and survival of hatchery-reared sport fish released for stock enhancement purposes. This study was conducted to evaluate the effect of water quality/source on growth and survival of larval spotted seatrout (Cynoscion nebulosus) reared in captivity. Trials were conducted both indoors under controlled conditions and in outdoor tanks. For the indoor trials, seatrout eggs were stocked into replicated (n = 4) 83-L tanks at 50,000 eggs/tank for either 2 or 9 days post-hatch (DPH). During this period, tanks received either filtered seawater, raw seawater, or filtered seawater containing marine microalgae. There was no significant difference (P>0.05) in survival of either 2 DPH (49.95 ± 13.6%) or 9 DPH (30.73 ± 14.2%) larvae regardless of water source. However, a significant difference was observed between the growth rates of 9 DPH larvae, as the larvae in the clear water treatment were significantly smaller (P = 0.01) than the two other treatments. Outdoor tanks (13,000-L) were stocked with 1,500 larvae (2 DPH or 9 DPH) (n = 3) which were reared for 30 days. Growth (TL) and survival rates in the outdoor tanks approximated 1.06 and 1.41 mm/day and 11 and 7.5%, respectively. There was no significant difference (P =0.15) in survival which was similar between the two age groups; a highly significant growth rate difference was shown. Results from this preliminary research indicate that current protocols used to rear juvenile spotted seatrout can be improved by increasing indoor rearing period.Life SciencesCollege of Science and Engineerin
The Effect of Physical Weight and Stimulus Spatial Location on Lexical Decision: Implications for Embodied Cognition
No full textTraditional models of cognition within cognitive psychology have utilised dualistic perspectives and
largely ignored the roles of the motor systems and bodily experiences. More recent embodied approaches have sought to combat this dualism by incorporating the motor systems and bodily experiences into their perspectives. Recent research has highlighted the role of bodily experiences in shaping cognition (Proffitt, 2006; Jostmann et al., 2009), how language comprehension can be embodied and grounded in physical experiences (Glenberg and Kaschak, 2002; Zwaan and Yaxley, 2003) and also how stimulus spatial location can influence responses (Meteyard et al.,
2008; Dunn et al., 2014). The present study aimed to explore those areas and provide empirical evidence in support as well as explore a gap in current research. The literature search indicated an abundance of embodied system research but a lack of research looking at possible interactions between the systems, it was this gap that was explored within the present study. Utilising a lexical decision task and methods similar to that of Proffitt (2006) three experiments were conducted. A total of 64 participants underwent standard and spatial lexical decision tasks. Three experiments were conducted exploring the bodily effect of weight, stimulus spatial effect and interactions between embodied systems.Results from the three experiments displayed a lack of support for
past research regarding the effect of the bodily experience of weight. Results also displayed a
main effect of word type leading to the indication that the comprehension of the word/non-word letter strings affected task performance. Analysis of results proposed that a cohesion effect between embodied systems facilitated task performance. It was concluded that further research is needed in order to fully understand the possibility of dominance or cohesion effects within an embodied perspective
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The importance of maternal shrub nutrient history, seedling soil nutrients, and freezing temperatures on avicennia germinans recruitment
No full textHuman-driven climate change is increasing the global range of Avicennia germinans
(L.) L., especially in communities in the Gulf of Mexico. Avicennia germinans propagules
establish in salt marshes along the Texas coast with high maternal energy invested in propagules
that can withstand abiotic environmental fluctuations. As these systems shift in dominance from
herbaceous to woody plants, biotic interactions, including energy transfer from a maternal plant
to its offspring, can affect the rate of change. Modifications in dispersal patterns and propagule
recruitment drive the population biology and subsequent community interactions within
mangrove-marsh ecotones. Fluctuations in nutrient availability, particularly with nitrogen and
phosphorus as limiting factors, influence the reproductive output of A. germinans.
This research analyzed the effects of maternal A. germinans shrub fertilization, soil
fertilization in early propagule and seedling growth stages, and the combination of maternal and
soil fertilization on propagule establishment, survival, and growth. Higher propagule weights
significantly increased percent survival and height across all treatment types. Nitrogen (N)
additions to the soil increased percent survival, and the combination of N maternal-shrub
fertilization and N-seedling soil fertilization increased growth of seedlings in height and leaf
production. Seedlings growing in phosphorus (P) soil had increased leaf production and the
combination of maternal P and soil NP greatly increased leaf production.
Propagule response to varying freezing temperatures in Corpus Christi and South Padre
Island was analyzed using maternal-shrub fertilized and unfertilized propagules. Experiencing a
harsh freeze (-8°C) for two hours, significantly reduced survival across all maternal treatments,
with a 20% overall survival. Thus, A. germinans populations will not be wiped out by a single -
8°C freeze and could possibly experience rapid recruitment from surviving propagules, leading
vi
to local adaptation. Propagules harvested from South Padre Island, a more southern location on
the Texas coast, grew taller as seedlings and had higher survival rates during a lighter freeze (-
2°C), and produced more leaves during a harsher freeze (-8°C). Nitrogen maternal-shrub
fertilization increased growth of Corpus Christi propagules, but only during the -2° freeze
treatment.
Assessing mangrove survival and growth in salt marshes under varying nutrient
conditions will provide insight into where A. germinans will become dominant as their global
livable range expands. Growth benefits from fertilizer additions parent plants and the substrate
during the seedling stage could indicate areas of future A. germinans “hotspots” where the
propagules produced may have increased viability, a larger growth form, and be more able to
withstand freezing temperatures as populations spread farther north.Life SciencesCollege of Science and Engineerin
Alternative spring break : a manual to assist in the planning and implementation of a service-learning trip
No full textA template was developed to guide the planning, implementation and evaluation of a service-learning alternative spring break trip. Discussion was based upon a trip designed by the author and implemented in March 2006. Participants were undergraduate students at Ball State University. The project provided background information on service-learning and current alternative breaks at colleges and universities across the United States. A compilation of components necessary to plan a trip was included. Additionally, recommendations were prepared for future coordinators.Thesis (M.A.)Department of Educational Studie
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Macroinvertebrate communities and decomposition rates of leaf and stem litter in a Texas saltmarsh-mangrove ecotone
No full textA thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Coastal and Marine System Science.After an extreme freeze event in 2021 caused extensive mangrove mortality and widespread top-kill to surviving mangroves and salt marsh vegetation along much of the Texas coast, it produced a massive flush of dead leaf and stem material in the ensuing litterfall. I questioned if there was a difference in macroinvertebrate community composition in leaf and stem litter and litter decomposition rates between Avicennia germinans (L) L, the black mangrove, and Batis maritima L, a halophytic succulent forb. In a field experiment, I used mesh litter bags to either allow or exclude macroinvertebrates and found no difference in macroinvertebrate community composition between the two litter types, suggesting they are generalists within a mesohaline and hypersaline environment. Wetness level of bags varied from dry, partially damp, mostly damp, and wet, and was significant in determining community composition parameters, with mostly damp bags having the highest abundance, richness, and diversity of macroinvertebrates. However, wetness level was not significant in determining litter decomposition (k). I found that leaf and stem litter is rapidly colonized and decomposed at 2-weeks post placement and then faunal abundance and diversity decline after 2 weeks, suggesting litter serves as a temporary “oasis” for macroinvertebrates. There was no difference in litter decomposition rate between mesh sizes, implicating that colonization by macroinvertebrates does not have a significant effect on litter decomposition, and rather it is likely being affecting by other abiotic and biotic factors or a combination of both. This study was the first to quantify B. maritima litter decomposition, with a rate of 0.098 g day-1, as compared to A. germinans litter decomposition of 0.024 g day-1. This research should inform management decisions by coastal land managers and conservationists when making management decisions concerning small invertebrate use of and effects on litter as communities shift from herbaceous saltmarsh to woody mangrove and influence the food webs of which small invertebrates are an important component.Physical and Environmental SciencesCollege of Scienc
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Freeze-Disturbance effects on biomass allocation in expansion of Black Mangrove (Avicennia Germinans) along a latitudinal gradient in Texas
No full textIn response to warming minimum temperatures, Avicennia germinans is encroaching poleward on the Texas Gulf Coast (TGC) into saline marshes dominated by Spartina alterniflora and Batis maritima. Increased Avicennia cover provides greater protection from soil subsidence and shoreline retreat. However, intense freeze disturbances cause widespread mangrove mortality reversing succession, and increasing the risk of soil subsidence and shoreline retreat due to the loss of below-ground biomass. We conducted a “natural experiment of opportunity” to measure below- and above-ground biomass allocation in Avicennia recovering from catastrophic disturbance caused by the 2021 Winter Storm Uri at sites along a freeze-disturbance gradient across the South and Central TGC. Port O’Connor (28.46°N) was the most severely affected site, Cohn Preserve on Mustang Island (27.71°N) was moderately affected, and Laguna Atascosa National Wildlife Refuge (26.35°N) was minimally affected (min. temp. °C ~ -9.0, ~ -7.4, ~ -5.5 respectively). A second freeze event occurred in December 2022 that severely affected Port O’Connor and moderately affected Cohn Preserve (min. temp. °C ~ -6.6, ~ -5.8 respectively). In an additional methods experiment, we quantified differences in root productivity in in-growth cores containing either peat moss or local substrate at each site. Multiple root ingrowth cores were inserted near the canopy edge of isolated Avicennia shrubs (n=6; 5 at Port O’Connor) at the three sites and collected at 4-month intervals (total cores = 102). Root productivity (g * (m-2 day1)) assessed in a one-way ANOVA and Tukey multiple comparisons, increased with increasing freeze-disturbance effects (F2,28 = 6.386, p<0.01, Port O’Connor: mean = 0.192, sd = 0.188, Cohn Preserve: mean = 0.065, sd = 0.081, Laguna Atascosa: mean = 0.047, sd = 0.089). Using the below-and above-ground relative growth rates to assess the root:shoot biomass allocation ratio, we found an increasing ratio (greater roots to shoots) with increased freeze disturbance (one-way ANOVA and Tukey HSD tests, F2,12 = 6.049, p<0.05, Port O’Connor: mean = 0.191, sd = 0.118, Cohn Preserve: mean = 0.061, sd = 0.066, Laguna Atascosa: mean = 0.015, sd = 0.01). Further, we found no clear trend in quantity or variability in root productivity between native and peat moss substrate types in root ingrowth cores for root biomass at any site (F2, 53 = 0.021, p=0.8). However, peat moss ingrowth cores did consistently have less root necromass after the Dec. 2022 freeze suggesting better survival or lower turnover. Peat moss ingrowth cores contained lower quantities of live root biomass indicating higher rates of root mortality or a stunting effect on root productivity post-second freeze. This finding suggests that cumulative impacts of two freezes occurring less than two years apart are greater than the effects of individual freezes. Increasing root productivity with greater freeze disturbance suggests that recovering standing root biomass may be important for the recovery of above-ground biomass in freeze affected Avicennia. Rapid recovery of below-ground biomass will also contribute to ameliorating rates of soil subsidence and shoreline retreat. Lastly, we found that peat moss is a viable substrate type for future root ingrowth studies if the focus of the study is on total root biomass. However, if a second freeze event occurs during the root ingrowth study, there may be unequal effects between peat moss and local substrate.Life SciencesCollege of Scienc
The biology of Australian weeds 58. Baccharis halimifolia L.
No full textThe genus name Baccharis is after the Greek bakkaris, an oil producing plant (later called 'Celtic valerian') (Parsons and Cuthbertson 1992). The species name halimifolia is derived from the Greek alimos meaning 'seas' and the Latin folium meaning 'leaf' (Parsons and Cuthbertson 1992). Baccharis halimifolia L. belongs to the family Asteraceae which is the largest family of flowering plants, comprised of over 1100 genera and 19 000 species (Zomlefer 1994). Baccharis is a large genus, comprised of over 400 species (Mahler and Waterfall 1964, Zomlefer 1994) distributed over seven geographical areas: Brazil, Andes Mountains, Andes-Patagonia, Guyanarum, south-eastern Brazil, Mexico (including western United States) and the Antilles (including the eastern United States) (Boldt 1989). In Australia, B. halimifolia is most commonly known as groundsel bush. 'Groundsel' refers to the groundsel-like flowering heads, as in plants in the Senecio genus (Parsons and Cuthbertson 1992). In its native region it is often referred to as saltbush (Stevenson 1969, Proffitt et al. 2005), groundsel tree (Altfeld and Stiling 2006), sea myrtle (Caccamise 1977, Dickens and Boldt 1985) and eastern baccharis (Adlerz 1980)
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