Effects of Gamma Irradiation on in Vitro Cultures of Selected Orchid Hybrids

Mutation breeding is an alternative strategy to conventional breeding. The physical mutagen, gamma (y) radiation, has long been used in various mutation breeding programmes. In this connection it is necessary to determine the optimum dose before starting any mutation breeding programme. In vitro cultured protocorm-like bodies (PLBs) of 2 orchid hybrids, Mokara Chark Kuan and Dendrobium Jacky were used to study the effects of yirradiation and to determine the optimum dose. The PLBs were irradiated with y-rays at different doses of 0, 25, 50, 75, 100, 125 and 150 Grays (Gy) in Set I and 0, 20, 40, 60 and 80 Gy in Set II of the experiment. A senes of observations on the effects of y-irradiation were recorded. Effects on genomic DNA were also observed. The present study showed that irradiation resulted in various degrees of lethality to in vitro cultures of both Mokara Chark Kuan and Dendrobium Jacky. Decrease in survival with increasing doses of y-irradiation was significantly observed. Optimum dose of y-irradiation for in vitro cultures of Mokara Chark Kuan and Dendrobium Jacky were estimated to be in the range of 20-40 Gy and 60-70 Gy respectively. Regeneration of plantlets was found to decline when higher irradiation doses were applied. Irradiation also has inhibited regeneration of in vitro cultures of both hybrids

Depth perception not found in human observers for static or dynamic anti-correlated random dot stereograms

One of the greatest challenges in visual neuroscience is that of linking neural activity with perceptual experience. In the case of binocular depth perception, important insights have been achieved through comparing neural responses and the perception of depth, for carefully selected stimuli. One of the most important types of stimulus that has been used here is the anti-correlated random dot stereogram (ACRDS). In these stimuli, the contrast polarity of one half of a stereoscopic image is reversed. While neurons in cortical area V1 respond reliably to the binocular disparities in ACRDS, they do not create a sensation of depth. This discrepancy has been used to argue that depth perception must rely on neural activity elsewhere in the brain. Currently, the psychophysical results on which this argument rests are not clear-cut. While it is generally assumed that ACRDS do not support the perception of depth, some studies have reported that some people, some of the time, perceive depth in some types of these stimuli. Given the importance of these results for understanding the neural correlates of stereopsis, we studied depth perception in ACRDS using a large number of observers, in order to provide an unambiguous conclusion about the extent to which these stimuli support the perception of depth. We presented observers with random dot stereograms in which correlated dots were presented in a surrounding annulus and correlated or anti-correlated dots were presented in a central circular region. While observers could reliably report the depth of the central region for correlated stimuli, we found no evidence for depth perception in static or dynamic anti-correlated stimuli. Confidence ratings for stereoscopic perception were uniformly low for anti-correlated stimuli, but showed normal variation with disparity for correlated stimuli. These results establish that the inability of observers to perceive depth in ACRDS is a robust phenomenon

Community awareness about tangible and intangible benefits of Sibuti Mangrove Forest, Sarawak, Malaysia

Mangrove forest is highly productive and provides enormous tangible and intangible benefits to the local communities. Millions of people are dependent on mangrove for their livelihoods around the world including Malaysia. Many researchers in Malaysia have focused on ecological and environmental aspects of mangroves; however very few research works are documented on social linkage aspect to this unique characteristic of forest particularly in Sarawak. Hence, this study focuses on community awareness about the benefits of Sibuti mangrove forest to the local community in Sarawak. Data was recorded from 60 respondents using simple random sampling techniques in three villages surrounding Sibuti mangrove forest through structured and semi-structured interview schedule. The coastal community was not depending on Sibuti mangroves forest in terms of direct benefits, however, low dependency was recorded on mangrove forest in term of crab and mollusk collection (55%), Nypa fruits collection (35%) and Nypa leaves collection (32%). Fishing was the only direct benefit, which was getting by the community (48%) from Sibuti mangrove forest and adjacent areas. The community believed that mangrove forest provide them indirect benefits such as breeding ground of fish, protecting their land from soil erosion, contributing towards land formation, filtering the water resource, increasing scenic view, providing food to the fish, working as nutrients hub for fishes, wildlife habitat, protection from floods, protection from cyclones/storms/tornados and protecting them from Tsunami. Most of the respondents were always willing to play role in the development of Sibuti mangroves, interested in learning about conservation and protection practices, while some (62%) were ready for volunteer role in conservation and protection if assign to them. Most of them i.e., 60% were ready to play role as volunteer and 77% was ready to work as facilitator. Majority (53%) was willing to pay donations. The educational, research and training program were welcomed by 98% of the respondents. The findings of the study suggest that forestry resource could be managed through community involvement for the well being of fishery resources, community livelihoods, wildlife and eco-tourism development

Human Capital Versus Market Signaling Theory: The Case with Adult Literacy

Human capital and market signaling theory are compared using data from the Statistics Canada Survey of Literacy Skills Used in Daily Activities (1990). The results indicate that both theories explain variations in annual income and number of weeks worked. Employers use education credentials (market signaling theory) to select employees who are then rewarded with earnings based on their literacy levels (human capital theory). Implications of these findings for policy and practice are presented

The performance of fine bubble diffusers.

Fine bubble diffusers are utilised within the activated sludge process to fulfil two requirements; they supply dissolved oxygen to satisfy the respiratory demands of the microbial population and maintain the mixed liquor suspended solids in suspension. The rate at which oxygen is transferred into solution by an aeration device, and the amount of energy used during the process will effect the efficiency and hence the cost of treatment. There often exists a difference in wastewater oxygenation capacity compared to that of potable water under the same conditions. This reduction is due to the presence of mechanisms that inhibit the oxygen transfer process. This inhibition of oxygen transfer within wastewater is characterised by the alpha factor. There are a number of variables, be they physical, chemical or biological, that are believed to contribute towards the alpha factor. A comprehensive literature review of these factors is provided. Three distinct areas that influence the performance of fine bubble diffusers in a wastewater environment are examined. A photographic approach was used to investigate the influence of surfactants upon the bubble formation process with respect to fine bubble diffusers. Anionic surfactants were found to have a significant impact upon at the point of bubble formation, reducing the major and minor mean bubble diameters and producing a more uniform bubble size. In the presence of anionic surfactants, the generic type of diffuser material was found to determine the level of impact of the surfactant upon the bubble formation process with ceramic diffusers being the most adversely affected. The influence of the physical variables of depth of immersion, airflow rate, and generic type of diffuser material upon the oxygen transfer performance of fine bubble diffusers were investigated in a 6m deep aeration test rig. Comparisons of results in clean water and clean water with anionic surfactants were undertaken in order to simulate the effects of the alpha factor. In the presence of anionic surfactants, ceramic diffusers were found to be the most adversely affected in terms of oxygen transfer performance when compared to that of plastic and membrane diffusers. The alpha factor was found to be insensitive to increases in airflow rate per diffuser for the range 0.5 - 4m3/hr per diffuser. With respect to the influence of the depth of diffuser submergence upon the alpha factor, it was found that once the rising bubble plume had become fully developed at a depth of 1.75m, the alpha factor was found to be constant up to the maximum depth investigated of 5.75m. The causes and consequences of diffuser fouling are discussed. Investigations into the rate of fouling and the impact upon fine bubble diffuser performance are presented. Dynamic Wet Pressure (DWP) and Standard Oxygen Transfer Efficiency (SOTE) data are presented from several full-scale operational plants and two experimental rigs. The fouling of fine bubble diffusers was found to increase the DWP whilst decrease the SOTE. The degree of fouling was found to be related to the position of the diffuser within the treatment process where the greater the treatment received, the less the degree of fouling. The major inorganic foulant was identified as Calcium. The generic type of diffuser material was found to significantly affect the changes in the DWP during diffuser operation, with plastic diffusers being most adversely affected. The implication for practice of the research findings are discussed and it is recommended that the operational cost implications of the choice of specific diffusers be considered along with the capital costs when making future procurement decisions

Declining Volatility, a General Property of Disparate Systems: From Fossils, to Stocks, to the Stars

There may be structural principles pertaining to the general behavior of systems that lead to similarities in a variety of different contexts. Classic examples include the descriptive power of fractals, the importance of surface area to volume constraints, the universality of entropy in systems, and mathematical rules of growth and form. Documenting such overarching principles may represent a rejoinder to the Neodarwinian synthesis that emphasizes adaptation and competition. Instead, these principles could indicate the importance of constraint and structure on form and evolution. Here we document a potential example of a phenomenon suggesting congruent behavior of very different systems. We focus on the notion that universally there has been a tendency for more volatile entities to disappear from systems such that the net volatility in these systems tends to decline. We specifically focus on origination and extinction rates in the marine animal fossil record, the performance of stocks in the stock market, and the characters of stars and stellar systems. We consider the evidence that each is experiencing declining volatility, and also consider the broader significance of this.Comment: Accepted for publication in Palaeontology. 13 pages, 3 figure

Considering the Case for Biodiversity Cycles: Reexamining the Evidence for Periodicity in the Fossil Record

Medvedev and Melott (2007) have suggested that periodicity in fossil biodiversity may be induced by cosmic rays which vary as the Solar System oscillates normal to the galactic disk. We re-examine the evidence for a 62 million year (Myr) periodicity in biodiversity throughout the Phanerozoic history of animal life reported by Rohde & Mueller (2005), as well as related questions of periodicity in origination and extinction. We find that the signal is robust against variations in methods of analysis, and is based on fluctuations in the Paleozoic and a substantial part of the Mesozoic. Examination of origination and extinction is somewhat ambiguous, with results depending upon procedure. Origination and extinction intensity as defined by RM may be affected by an artifact at 27 Myr in the duration of stratigraphic intervals. Nevertheless, when a procedure free of this artifact is implemented, the 27 Myr periodicity appears in origination, suggesting that the artifact may ultimately be based on a signal in the data. A 62 Myr feature appears in extinction, when this same procedure is used. We conclude that evidence for a periodicity at 62 Myr is robust, and evidence for periodicity at approximately 27 Myr is also present, albeit more ambiguous.Comment: Minor modifications to reflect final published versio

Middle School Teacher Perspectives of LDC in a Rural Southeastern North Carolina School District

The mixed-method phenomenological study surveyed middle school teacher perceptions of the Literacy Design Collaborative (LDC). The study population consisted of 16 sixth through eighth grade English language arts, science, or social studies teachers. The data for this study were analyzed from the 2011-2012 school year until the 2015-2016 year. The researcher utilized Stufflebeam’s (2003) context, input, process, product (CIPP) model to create the research questions. The following research questions guided the study: (1) To what extent does the LDC model influence middle school teacher decisions in the type of the instructional strategies they choose to use in their classrooms; (2) What specific types of instructional strategies do middle school teachers report to use when implementing the LDC model; (3) To what extent do teachers feel adequately prepared to make decisions regarding the types of instructional strategies they choose to implement in the LDC classrooms; and (4) What instructional challenges or successes do teachers experience when they implement the LDC model? The findings of this study indicated the need for providing professional development regarding the implementation of LDC for middle school teachers. Additionally, it was suggested that research of program implementation and implementing programs with fidelity take place for district leadership as well as principals. It was also recommended that a thorough needs assessment be conducted within the school district

Kentucky Quilts: Roots & Wings

1998 Kentucky Folk Art Center exhibition catalog depicting Kentucky quilts.https://scholarworks.moreheadstate.edu/kfac_exhibition_catalogs/1016/thumbnail.jp