bluuebunny/crossref_metadata_2025 huggingface dataset:
Snake spectacle vessel permeability to sodium fluorescein
Authors: Bellhorn Roy W. , Strom Ann R. , Motta Monica J. , Doval John , Hawkins Michelle G. , Paul‐Murphy Joanne
Published: June 2017

Objective

Assess vascular permeability of the snake spectacle to sodium fluorescein during resting and shedding phases of the ecdysis cycle.

Animal studied

Ball python (Python regius).

Procedures

The snake was anesthetized, and spectral domain optic coherence tomography was performed prior to angiographic procedures. An electronically controlled digital single‐lens reflex camera with a dual‐head flash equipped with filters suitable for fluorescein angiography was used to make images. Sodium fluorescein (10%) solution was administered by intracardiac injection. Angiographic images were made as fluorescein traversed the vasculature of the iris and spectacle. Individually acquired photographic frames were assessed and sequenced into pseudovideo image streams for further evaluation

Conclusions

Fluorescein angiograms of the snake spectacle were readily obtained. Vascular permeability varied with the phase of ecdysis. Copious leakage of fluorescein occurred during the shedding phase. This angiographic method may provide diverse opportunities to investigate vascular aspects of snake spectacle ecdysis, dysecdysis, and the integument in general.
Effect of body position, eyelid manipulation, and manual jugular compression on intraocular pressure in clinically normal cats
Authors: Rajaei Seyed Mehdi , Asadi Faezeh , Rajabian Mohammad Reza , Ostadhassan Hesam , Crasta Manuela
Published: June 2017

Objective

To determine the effect of body position, eyelid manipulation, and manual jugular compression on intraocular pressure (IOP) in clinically normal cats.

Animal studied

Twenty‐one adult client‐owned domestic shorthair cats

Procedures

The IOP was measured by means of rebound tonometer. A baseline IOP was measured in all cats in ventral recumbency with normal head position (horizontal to the ground) with no pressure on the neck or eyelids. To measure the IOP in dorsal recumbency, each cat was held in the dorsal recumbency position for 5 min. Four different manipulations were used, including maximal dorsoventral extension of the eyelids, lateral eyelid extension, manual compression of the ipsilateral jugular vein, and manual compression of both jugular veins. IOP after all the manipulations was measured in ventral recumbency.

Results

Overall the mean ± SD IOP values of all eyes in ventral recumbency, dorsal recumbency, maximal dorsoventral extension of the eyelids, lateral eyelid extension, compression of the right jugular vein, compression of the left jugular vein, and compression of the both jugular veins were 16.1 ± 2.9 mmHg, 17.1 ± 5.0 mmHg, 21.7 ± 5.8 mmHg, 22.4 ± 5.6 mmHg, 15.0 ± 3.7 mmHg, 14.9 ± 3.7 mmHg, and 16.1 ± 4.6 mmHg, respectively. IOP was increased significantly in maximal dorsoventral extension of the eyelids (P = 0.001) and lateral eyelid extension (P = 0.001) compared to baseline.

Conclusions

Results of this study may be beneficial for clinicians to be aware of the effects of body position, traction, and compression of the eyelids and neck on IOP during ophthalmic examination in cats.
EXPERIMENTAL INVESTIGATION OF CFRP STRENGTHENED I-SHAPED COLD FORMED STEEL BEAMS
Authors: Chakravarthy Nahushananda , Naganathan Sivakumar , Hsien Aun Jonathan Tan , Kalavagunta Sreedhar , Mustapha Kamal Nasharuddin , T. R. Veena
Published: June 2017

Cold formed steel differ from hot rolled steel by its lesser thickness and weight. The cold formed steel applicable in roof purlin, pipe racks and wall panels etc. Due its lesser wall thickness the cold formed steel member subjected to buckling. The enhancement of load carrying capacity of the cold formed steel member can be achieved by external strengthening of CFRP. In this study cold formed channel members connected back to back to form I shaped cross section using screws. These built up beam members were 300mm, 400mm and 500mm in length with 100mm screw spacing and edge distance of 50mm were chosen for testing. CFRP fabric cut according to length, width of built up beams and wrapped outer surface of beam using epoxy resin. Experiments were carried out in two sets firstly plain built up beams and secondly CFRP wrapped beams. The test results shows that increased load carrying capacity and reduction in deflection due to CFRP strengthening. Experimental results were compared with AISI standards which are in good agreement. Experimental results shows that CFRP strengthening is economic and reliable.
OPTICAL FIBER LOSS ANALYSIS FOR AN APPLICATION OF SPECTROPHOTOMETER SYSTEM
Authors: Che Abd Rashid Nurfatihah , Ngajikin Nor Hafizah , Mohd Yusof Khairunnisa , Isaak Suhaila , Azmi Asrul Izam , Arsat Rashidah
Published: June 2017

Loss analysis due to the insertion of optical fiber in short wavelength spectrophotometer system is experimentally conducted to improve resolution and flexibility of the system design. In this paper, type, length and bending diameter of the optical fiber are analyzed as a preliminary work towards the development of a low-loss spectrophotometer system. In order to analyze a suitable type of fiber to be adopted in this system, a 20 mm length and 0 mm bending diameter of a single-mode fiber (SMF), multi-mode fiber (MMF) and Polymethyl methacrylate (PMMA) fiber are tested. The length and bending diameter of the suitable fiber is then varied from 20 mm to 60 mm and 6 mm to 22 mm respectively. In this paper, light emitting diode (LED) centered at 525 nm wavelength with 35 nm full width half maximum (FWHM) is used as the spectrophotometer light source while silicon photodiode is used as the detector. In this work, photodetector output voltage is recorded to analyze the loss contributed by these three parameters. At this particular wavelength, PMMA is found to be a suitable fiber to be adopted due to its minimal loss performance. Besides the fiber type, having a minimal fiber length with maximal fiber bending diameter can reduce loss due to the insertion of optical fiber in spectrophotometer system, hence improving the spectrophotometer resolution performance.
FINITE ELEMENT ANALYSIS ON THE BEHAVIOR OF SLAB-COLUMN CONNECTIONS USING PVA-ECC MATERIAL
Authors: Tambusay Asdam , Suprobo Priyo , Faimun Faimun , Amiruddin Arwin
Published: June 2017

A 3D finite element analysis was carried out to study the behavior of slab-column connections in a flat slab structure under combined gravity and cyclic lateral load. Prior to simulating the behavior of the proposed model, the slab-column connection specimen by using standard orthogonal stud rail from the previous study was modeled with the purpose of verifying the results using finite element tool. Given that numerical simulation was undertaken using ABAQUS to predict the structural behavior of the above-mentioned structure. With regard to providing an accurate result, a sensitivity analysis was performed by changing different parameters, such as dilation angle, viscosity parameter, and damage parameter-strain on both in tension and compression. After gaining the close resemblance to the previous study, the proposed models were then simulated using the similar technique. In the proposed model, drop panel element was used as a replacement of stud rail. Additionally, the engineered cementitious composite material using polyvinyl alcohol fibers (PVA-ECC) was also employed due to its strain capacity of 3-5% under tension compared to 0.01% of conventional concrete. Through this study, the results showed that the effect of utilizing the PVA-ECC material could significantly improve the specimen behavior and damage tolerance.
PHYSICAL DISPERSION OF NANOCARBONS IN COMPOSITES–A REVIEW
Authors: M. A. Alsharef Jamal , Taha Mohd Raihan , Ahmed Khan Tanveer
Published: June 2017

Recently, nanocarbons (carbon nanofibers (CNFs) and carbon nanotubes (CNTs)) have been used efficiently in numerous research works to significantly enhance the mechanical properties of composites. With their amazing mechanical properties and exceptionally high aspect ratios, nanocarbons (NCs) are seen as one of the most beneficial nanomaterials for nano-reinforcement. The dispersion of NCs is one of the key factors that strongly influence the properties of nanocomposites. Several researches have been carried out with chemical agents to achieve a consistent dispersal of carbon nanomaterials in water, although, if the process is uncontrolled, it can shorten or damage the NCs or even dissolve them, and this can have a negative effect on the composites as well. Therefore, if NCs are to be used as reinforcement for composites, physical methods have to be employed to disperse the NCs before they can be mixed into the composites. This paper presents an overview of the different types of NCs, their different uses and the research conducted for the dispersion of NCs by chemical and physical methods. Furthermore, a summary is given of the measurement and characterization of the dispersibility of NCs.
MALAYSIAN SEA WATER LEVEL PATTERN DERIVED FROM 19 YEARS TIDAL DATA
Authors: Md Din Ami Hassan , Abdul Hamid Amalina Izzati , Mohammad Yazid Nornajihah , Tugi Astina , Khalid Nur Fadila , Mohd Omar Kamaludin , Ahmad Anuar
Published: June 2017

Long-term water level changes have generally been estimated using tidal data. Tide gauges are common tools used to determine the continuous time series of relative water level. This paper presents an effort to interpret the water level from tidal data over Malaysian seas. There are 21 tide gauge stations involved and taken from Permanent Service for Mean Sea Level (PSMSL) with monthly averaged data from 1993 to 2011. The monthly tidal data is then converted to tidal sea level anomaly. For sea level trend analysis, robust fit regression is employed. Next, the sea levels were analysed based on the pattern of seasonal variation and extreme meteorological effects such as El-Nino and La-Nina.  In summary, the relative sea level trend in Malaysian seas is rising and varying from 2 to 6.5 mm/yr. This study offers valuable sea level information to be applied in wide range of climatology, related environmental issue such as flood and global warming in Malaysia.
Self-Drive Tourism Route in Terengganu: An Application of Goal Programming Model
Authors: Hashim Zakiah , Ismail Wan Rosmanira
Published: June 2017

This study presents a goal programming approach to determine the best self-drive tourism route in Terengganu. The goal programming was formulated based on the model of Traveling Salesman Problem (TSP). This study involved seven cities in Terengganu which can be connected by road network. The data of the tourist attractions for each city was used in this study. The model of self-drive tourism route was constructed so as to connect all these seven cities by minimizing the travel distance, minimizing accommodation costs and maximizing the total number of tourist attractions. To achieve the objectives of this study, we develop the goal programming model that considers three model structures with each of them consists three goal constraints which are subjected to four hard constraints. This model has been solved using LINGO12.0 software. The results obtained from each model structures will be compared in order to get the most optimum route for self-drive tourism. The result showed that the first model structure was suitable to be used because this model structure gave the optimum result compared to other model structures. It produced the minimum total traveling cost of RM967.70 compared to the model structure two of RM977.10 and model structure three of RM1233.10.
Menilai Teknik Penyebatian Kemahiran Berfikir sebagai Satu Alternatif untuk Meningkatkan Kemahiran Berfikir dan Memahami Mata Pelajaran Fizik
Authors: Hashim Badariah , Abd Rahman Nurulhuda , Yahya Razak Abd. Samad
Published: June 2017

This research is intended to evaluate the use of the infusing thinking skills technique in teaching Form Four Physics in the topic of heat through the students’ achievements in the Critical Heat Test. The research involves the types of thinking skills, which are the parts-whole relationships, comparing and contrasting, and conceptualization. Teachers need to choose the most suitable type of thinking skills for the topic that will be taught in order to attain the learning outcome required. Additionally the infusing thinking skills technique, along with thinking skills, also contain the training of mind of habits in the behavior of students and metacognition whereby students will reflect on the thinking skills process during the teaching and learning activity. The use of thinking maps according to the type of thinking as mentioned, can help students think in step by step sequence. The methodology of the study is quasi-experimental and shows the disproportionate test design of the pre- and post-test groups. Research samples are purposive sampling, containing 30 people for each treatment group and control group. Two schools in Kinta Utara were involved in this study. Results show that there are significant differences in test-t, that is the score increment (critical heat posttest score-pretest score) of the treatment group as compared to the control group. It is found that the infusing thinking skills technique is suitable to enhance thinking skills and the students understanding of the heat topic. This technique is an alternative for teachers to apply various types of thinking skills required in Physics to train thinking skills to the students. Through conceptualization skills, students will be able to find Physics concepts from what they already know and from their daily experiences by using conceptual maps.
Pembangunan Modul Kemahiran Berfikir Aras Tinggi di dalam Mata Pelajaran Sains Sekolah Rendah: Analisis Keperluan Guru
Authors: Hassan Mohd Nazri , Mustapha Ramlee , Nik Yusuff Nik Azimah , Mansor Rosnidar
Published: June 2017

Teaching Higher Order Thinking Skills (HOTS) has its own challenges and need to be emphasized in the curriculum as it is one of the skills of the 21st century. HOTS is among six main characteristics of students who aspire Ministry of Education to succeed globally. However, studies on the effectiveness of the module KBAT in science subjects still not carried out. Hence, the purpose of this study was to develop and evaluate the effectiveness of teaching modules based on higher order thinking skills in science subjects in primary schools. The first phase of this study is to identify the needs of teachers of science on higher-order thinking skills module. The needs analysis also aims to determine the need and willingness of teachers to KBAT module in the teaching of science in primary schools. The initial analysis is carried out based on the protocol requirements interview involving 6 teachers teaching science subjects in six primary schools. The results showed that the willingness of teachers in the implementation and knowledge is minimal. Teachers are also not mastered the skills to integrate elements of higher order thinking skills in science teaching. Students facing dificulties to understand the questions as well as the teachers to develop high-level questions are identified problems faced by teachers. The interview data also shows teachers need simple guidance material or HOTS module to use for teaching and learning in the classroom.
Tren Pembelajaran Menggunakan Multimedia Interaktif dalam Bidang Pendidikan Teknikal: Satu Sorotan Literatur
Authors: Salsidu Siti Zulaidah , Azman Mohamed Nor Azhari , Abdullah Mai Shihah
Published: June 2017

Technology should be in harmony with the progress of education in the country. The rapid development in information technology and computing, indirectly change the education system in Malaysia. Teachers nowadays just not teach by “chalk and talk”, but they are also exposed to the utilization of technology in teaching. This scenario triggers the rapid usage of Information Technologies in teaching and learning process. This study was intended to display the trend of learning using Interactive Multimedia in Technical Education. It examined and reviewed  the changing  trends of  Multimedia Interactive Learning patterns of  the usage of multimedia educational media with emphasis in Technical Education between the years of 1900-2013 and served as the conceptual framework for the study. Thus, it forecasts the perspective on the usage of Interactive Multimedia and could assist the learning and teaching process in the school.
Faktor-Faktor yang Mempengaruhi Keberkesanan Amali Kerja Kayu dari Perspektif Pelajar Sekolah Menengah Vokasional di Provinsi Acheh
Authors: Fachrah Lailan , Hasbullah Nor Azlina , Ab Rahman Ashah
Published: June 2017

This study aims to identify factors that influence the effectiveness of practical woodworking and determine the effectiveness of practical woodworking from the perspective of students of secondary vocational schools in the province of Aceh. Factors studied were the workshop equipment, safety workshops, teaching skills, the workshop environment and student interest. This study was designed to investigate the significant differences concerning factors woodworking practical effectiveness based on demographic factors. A total of 130 respondents were randomly selected from six vocational schools in the province of Aceh. The instrument consists of a set of questionnaire consisting of 49 items and distributed to second level students. Data analysis using the two types of statistics, namely descriptive statistics and statistical inference. The results showed no significant difference between factors woodworking practical effectiveness based on demographic factors except the income level of parents and the parents of the respondents work. The results of multiple linear regression analysis stepwise method found that only four factors (environmental factors workshops, the students interest, the skills of teachers and workshop equipment factors) that affect the practical effectiveness of woodworking with the correlation coefficient R = 0.779. This shows there is a significant effect of the four factors, the effectiveness of practical woodworking, accounting for 60.6% (R2 = 0.606) changes in the variance in effectiveness of hands-on woodworking, and between the four factors, the workshop environment is the factor that most influences the effectiveness practical woodworking by contributing 43.3% (R2 = 0.433) of the variance in effectiveness of practical woodworking. The main implication of this study is the need for attention from the authorities to be more serious in efforts to improve the facilities and infrastructure in the workshop as well as security issues in practical workshops so that the effectiveness of the woodwork to be more robust.
Effect of PDEODE Teaching Strategy on Turkish Students' Conceptual Understanding: Particulate Nature of Matter
Authors: Demircioğlu Hülya
Published: June 2017

The aim of this study is to determine the effect of activities developed in accordance with PDEODE teaching strategy on students’ understanding of the particulate nature of matter. The sample of the study consists of the first grade students who study in the Primary School Teacher Education Program. In order to determine the conceptual change on students a test consisting of 8 questions was applied to the sample. This test was applied as pre-test, post-test and delayed post-test. The difference between the measurements was found statistically significant (p<0.05). This result shows that the treatment promotes the conceptual change and enhances students’ conceptual understanding. As a result of a post-hoc test (Tukey HSD test) it was established that there is a statistically significant difference between the means of pre-test and post-test, and pre-test and delayed test (p<0.05), there isn’t a significant difference between the means of post-test and delayed test (p>0.05).
Cognitive factors as predictors of accented speech perception for younger and older adults
Authors: Ingvalson Erin M. , Lansford Kaitlin L. , Fedorova Valeriya , Fernandez Gabriel
Published: June 2017

Though some studies suggest that older adults are not differentially impacted by foreign-accented speech relative to younger adults, other studies indicate that older adults are poorer at perceiving foreign-accented speech than younger adults. The present study sought, first, to clarify the extent to which older and younger adults differed in their perception of foreign-accented speech. The secondary aim was to elucidate the extent to which the cognitive mechanisms supporting accented speech perception differ for older and younger adults. The data indicated that older adults were poorer at perceiving accented speech than younger adults. Older adults' speech perception accuracy was associated with a significant main effect of working memory as well as significant interactions between hearing acuity and cognitive flexibility and between hearing acuity and inhibitory control. Younger adults' speech perception accuracy, in contrast, was associated with a significant interaction between hearing acuity and processing speed. It therefore appears that the differences in performance between younger and older adults observed here may be attributable to differences in the cognitive mechanisms that support accented speech perception.
A Comparison of the effects of several concentrations of oxgall in platings of soil fungi
Authors: Miller J.J. , Peers D.J , Neal R.W.
Published: June 2017

A study was made of the effect of adding varying concentrations of dehydrated bile to soil extract agar and potato dextrose agar in platings from two Ontario soils. The development of colonies of bacteria and actinomycetes was retarded, but no decrease was noted in the number of fungus colonies that appeared in the plates. The crowding effect of certain bacteria and fungi was lessened, facilitating the counting and isolation of individual fungus cultures.
Influence of moisture on rate of decay of loblolly pine root wood by Heterobasidion annosum
Authors: Kuhlman E. G.
Published: June 2017

Root segments of loblolly pine (Pinus taeda L.) were decayed by Heterobasidion annosum (Fr.) Bref. (=Fomes annosus (Fr.) Karst.) over a broad range of wood (33–317%) and soil (36–259%) moisture contents in modified soil-block tests. Maximum weight loss occurred at 50–286% wood moisture content. Decay was inhibited at wood moisture contents over 290%. Water moved rapidly into the root segments by capillarity, and some decay occurred within 2 weeks. Water uptake was faster in inoculated segments than in noninoculated segments at a soil moisture content of 172% of the 0.2 bar (1 bar = 100 kPa) moisture content.
Aspects infrastructuraux des altérations des anthères de Silene dioica parasitées par Ustilago violacea
Authors: Audran Jean-Claude , Batcho Mekinto
Published: June 2017

The structural characteristics of the sporogenous and parietal tissues of healthy anthers of Silene dioica (L.) Clairv. (Caryophyllaceae) are described as well as those of anthers infected by Ustilago violacea (Pers.) Rouss. (Ustilaginales). In infected anthers, the invading dikaryotic mycelium grew intercellularly and very rarely penetrated the cells. The pathogen stopped stamen histogenesis at an early stage, causing necrosis specifically of the sporogenous tissue either directly or following hypertrophy. Five stages were distinguished during the histological modifications leading to anther destruction. (1) First, the mycelium developed in the anther filament and spread throughout the superficial tissues of the anther without causing histological changes in the anther. (2) Then, some sporogenous cells began to show necrosis and formed compact masses. (3) An increasing number of sporogenous cells became necrotic following strong vacuolisation and hypertrophy. (4) Hyphae grew profusely in the necrotic mass of sporogenic cells. (5) Finally, the fungus produced teliospores which filled the sporangial cavity.
Effects of sulphur dioxide and ozone, singly or in combination, on membrane permeability
Authors: Beckerson D. W. , Hofstra G.
Published: June 2017

The effects of 0.15 ppm sulphur dioxide and (or) 0.15 ppm ozone on membrane permeability, measured by electrical conductivity of solute leakage, were determined for soybean, white bean, cucumber, and radish. Solute leakage increased significantly prior to visible injury for soybean and white bean exposed to 0.15 ppm ozone alone. This results in water-soaked lesions on the upper leaf surface prior to visible coloured necrotic lesions and is representative of a "leaky" plasmalemma. The sulphur dioxide – ozone mixture did not increase solute leakage above that of the control for white bean and soybean. Therefore, the presence of sulphur dioxide, in combination with ozone, attenuates or reduces the effects of ozone on increasing membrane permeability of white bean and soybean. Ozone alone did not affect membrane permeability in cucumber and radish. The sulphur dioxide – ozone mixture, which produced more injury than ozone alone, did increase membrane permeability temporarily for radish and cucumber but this occurred only after visible injury symptoms appeared. Overall, the effects of the pollutants singly or in combination on membrane permeability appear to offer an explanation of differences in species responses.
Effects of dehydration treatments on germination, seedling vigour, and cytoplasmic leakage in wild oats and birdsfoot trefoil
Authors: McKersie B. D. , Tomes D. T.
Published: June 2017

The stage in germination at which birdsfoot trefoil (Lotus corniculatus L. cv. Carroll) seeds and wild oat (Avena fatua L.) embryos became sensitive to dehydration was determined using percent germination, seedling vigour, and cytoplasmic leakage as indicators of cellular damage. Dehydration of seeds or embryos in the early stages of germination did not impair the subsequent germination or vigour of the seedling. In addition, cytoplasmic leakage during rehydration remained low. Dehydration of wild oat embryos grown on a germinating medium for 24 h or of birdsfoot trefoil seeds 18 h after the start of imbibition resulted in decreased germination and vigour and increased cytoplasmic leakage during rehydration. Damage to sensitive birdsfoot trefoil seeds occurred only in samples dehydrated below 20% moisture. The increase in cytoplasmic leakage from damaged seeds presumably reflects a loss in membrane integrity as a result of dehydration which may contribute to the reduced germination and vigour of the seeds.
Studies on the development of the air pores and air chambers of Marchanda paleacea. II. Ultrastructure of the initial aperture formation with particular reference to cortical microtubule organizing centres
Authors: Apostolakos P. , Galatis B.
Published: June 2017

The initiation of the intercellular spaces (ISs) of the initial apertures (IAs) follows the formation of surface cavities (SCs). The latter represent slight deepenings in the external periclinal walls of particular superficial thallus cells at the regions where their anticlinal walls meet one another. This event keeps pace with the deposition of wall pads at the wall junctions below the SC. Afterwards, the thickened wall areas are detached and thus the IS is initiated. By an inward development the IS reaches the subprotodermal layer. This is carried out by the coordination of three gradual processes: the inward spreading of the local wall thickening and the following detachment and expansion of the thickened regions. The findings favour the conclusion that the opening of the IS is the outcome of a highly controlled morphogenetic process. The interphase IA cells possess a well-organized cortical microtubule (MT) cytoskeleton, particularly at the area where the IS opens. In these regions, sets of anticlinal and periclinal MTs appear. During the SC stage the anticlinal MTs dominate, while during IS formation, the periclinal ones are most abundant. The above MTs, as well as other ones entering deeper in the cytoplasm, initially converge on the cortical cytoplasm adjacent to the SC and later on the region surrounding the lower part of the growing IS, where vesicles and endoplasmic reticulum are gathered. The observations suggest the continuous function of cortical MT organizing centres in the cytoplasm and (or) the adjoining plasmalemma, initially underneath the SC and later below the lower part of the growing IS, where local wall thickenings are deposited.
Import and unloading of 14C assimilate into mature leaves of Coleus blumei
Authors: Fisher David G. , Eschrich Walter
Published: June 2017

Mature leaves of Coleus blumei Benth. were tested for their ability to import 14C assimilate, to unload and metabolize it, and to transfer it to the mesophyll. To enhance the potential for import, plants were preconditioned by removal of shoot tips and axillary branches, by 48 h of darkness, and by removal of roots. One mature leaf on each plant was isolated in a CO2-free chamber and kept in the light or dark while the rest of the plant was exposed for 5 h to light and 7.4 MBq 14CO2, followed by 7 h of 12CO2. Autoradiographs showed that label imported into sink leaves exposed to the light was most concentrated in the major veins, but that considerable activity also occurred in the mesophyll at the base of the lamina and adjacent to the major veins. In general, sink leaves kept in the dark imported much less label, but in one case mesophyll labeling was observed in such a leaf. Microautoradiography of sink leaf midveins indicated that 14C was always translocated in the phloem. Low concentrations of sucrose and glucose accumulated in intercostal regions of both lighted and darkened sink leaves within 12 h of plant illumination. Chromatography of intercostal areas of the sink leaves showed that the imported assimilate was unloaded and metabolized into a number of other compounds, which indicates that mature leaves of Coleus can be converted into genuine sinks.
Quantitative studies in early ovule development. I. Intraindividual variation in Nothofagus antarctica
Authors: Scagel R. K. , Maze J. , Bohm L. R. , Vogt N. L.
Published: June 2017

The multivariate nature of ovule development in Nothofagus antarctica (Forst.) Oerst. was examined. In addition to a general increase in variable values, there were concomitant increases in variable variances and changes of intercorrelations. An increase in variation and change of intercorrelations also occur with phylogeny. These results emphasize the common phenomenological basis of ontogeny and phylogeny. They also demonstrate the necessity of a multivariate view in studying both evolution and development. The quantitative changes that occur with ontogeny suggest that generalizations about development should be sought in the realm of the generation of complexity and organization, an area also addressed by a new evolutionary theory based on nonequilibrium thermodynamics.
Biomass accumulation by Rhexia virginica and Triadenum fraseri along two lakeshore gradients: a field experiment
Authors: Sharp Mirek J. , Keddy Paul A.
Published: June 2017

Lakeshore plants are distributed along many gradients, two of which are exposure to waves and water depth (height on the shoreline). Not only does disturbance vary along these gradients, but the rate of recovery after disturbance may vary as well. We therefore tested whether biomass accumulation in two shoreline plants, Triadenum fraseri and Rhexia virginica, was influenced by these two gradients, and whether the responses of the two species differed. The exposure gradient was represented by three substrate types (measured by soil organic content) and the height gradient was represented by three positions relative to the lower limits of shoreline shrubs. The greatest accumulated biomass for both species was found below the lower limits of shrubs in organic substrates. The rate of recovery after disturbance would therefore be lower on sandy shores, even though such shores are more regularly disturbed. Rhexia virginica is normally restricted to substrates with an intermediate organic content, but there is no evidence that it is narrowly specialized upon this substrate as it actually grew better in the organic treatment. Rhexia virginica did not respond to favourable changes in either experimental factor when the other factor was not also favourable to growth. Triadenum fraseri, however, increased in biomass when one of the factors was favourably changed, regardless of the second factor. These differences may partially explain the more restricted distribution of R. virginica on shorelines.
Fossil flowers and leaves of the Ebenaceae from the Eocene of southern Australia
Authors: Basinger James F. , Christophel David C.
Published: June 2017

Numerous flowers and a diverse assemblage of leaves are mummified in clay lenses in the base of the Demons Bluff Formation overlying the Eastern View Coal Measures. Fossil localities occur in the Alcoa of Australia open cut near Anglesea, Victoria, Australia. Flowers are tubular, less than 10 mm long, and about 5 mm wide. Four sepals are connate forming a cup-shaped calyx. Four petals are fused in their basal third and alternate with sepals. Flowers are all unisexual and staminate. Stamens are epipetalous and consistently 16 in number, arranged in 8 radial pairs. Pollen is subprolate, tricolporate, and about 32 μm in diameter. The exine is smooth to slightly scabrate. A rudimentary ovary occurs in some flowers. Sepals usually have a somewhat textureless abaxial cuticle with actinocytic stomata. Some sepals, however, have frill-like cuticular thickenings over some abaxial epidermal cells and some subsidiary cells with pronounced papillae overarching guard cells. One of the more common leaf types found associated with the flowers is characterized by the same peculiar cuticular thickenings and overarching papillae on subsidiary cells that occur on sepals. This cuticular similarity indicates that flowers and leaves represent a single taxon. Leaves are highly variable in size and shape but are consistently entire margined, with pinnate, brochidodromous venation. The suite of features characterizing the flowers is unique to the Ebenaceae. Flowers of many extant species of Diospyros (Ebenaceae) closely resemble the fossil flowers. Fossil leaves, too, are typical of leaves of extant Diospyros. Both flowers and leaves are considered conspecific and have been assigned the name Austrodiospyros cryptostoma gen. et sp. nov. The Anglesea fossils represent one of the earliest well-documented occurrences of the Ebenaceae and are the earliest known remains of Ebenaceae from Australia. They support the hypothesis of a Gondwanan origin for the family with late Tertiary diversification in the Malesian region.
Phyllotactic patterns and transitions in Abies balsamea
Authors: Zagórska-Marek Beata
Published: June 2017

Phyllotactic patterns, as indicated by the number of helices in opposed parastichy pairs, were determined in elongated shoots. Twelve patterns were found, including very rare patterns such as tetrajugy and secondary bijugy. Typically, the same pattern was repeated each year along a particular axis. Changes in pattern occurred between annual growth increments, more rarely within one increment. Pattern changes were not random, rather they occurred in a manner that minimized the change in the number of helices in the opposed parastichy pairs. A reversal in the direction of the ontogenetic helix often accompanied a pattern change.
Seedling recruitment of 11 wetland plant species along a water level gradient: shared or distinct responses?
Authors: Keddy Paul A. , Ellis Timothy H.
Published: June 2017

Where many different plant species occupy an environmental gradient, the responses of their offspring to that gradient could show one of two patterns. All species could have similar requirements for maximum recruitment, in which case all would show maximum germination and emergence in the same region of the gradient ("shared responses"). Alternatively, each species could have different requirements for recruitment and therefore would show maximum recruitment in different regions of the gradient ("distinct responses"). The objective of this study was to test between these two alternatives in plants occurring along a water level gradient. Seeds of 11 wetland species were allowed to germinate in sand along a gradient of water depth, ranging from 10 cm above to 5 cm below the substrate surface. Scirpus americanus, S. validus, Sagittaria latifolia, Typha angustifolia, and Lythrum salicaria showed no significant response to this gradient, while Spartina pectinata, Polygonum punctatum, Bidens cernua, Acorus calamus, Alisma plantago-aquatica, and Eupatorium perfoliatum did. However, the six species in the latter group did not exhibit shared preferences along the water depth gradient. These different recruitment patterns were consistent with adult distributions in the field. Most species showed some recruitment at all water levels examined, suggesting that they have broad tolerance limits for water level in the recruitment phase of their life history.
A Costa Rican black mildew found in Everglades National Park, Florida
Authors: Farr M. L. , Schoknecht Jean D. , Crane J. L.
Published: June 2017

Dimerina dodonaeae is redescribed and illustrated and a new combination is proposed for this species in Episphaerella.
Leaf injury to bean plants grown in carbon dioxide enriched atmospheres
Authors: Ehret David L. , Jolliffe Peter A.
Published: June 2017

Bush bean (Phaseolus vulgaris L.) plants grown in atmospheres enriched with CO2 (1400 μL L−1) showed marked reductions in photosynthetic capacity and accelerated chlorosis of primary leaves. Leaf injury was observed only in CO2-enriched plants, but the degree of injury was regulated by secondary factors, light and temperature. Conditions of relatively high light intensity (340–370 μmol m−2 s−1 photosynthetic photon flux density) or cool temperature (20 °C) promoted leaf injury of CO2-enriched plants. Leaf starch accumulation was highest under conditions that caused injury. The enhanced chlorosis and corresponding decline in photosynthetic activity, however, were not related to changes in stomatal diffusive resistance or leaf water status. Contaminant gases, such as ethylene, were not detectable in the CO2-enrichment chambers.
The effects of taxol and colchicine on microtubule and microfibril arrays in elongating plant cells in culture
Authors: Weerdenburg Carol , Seagull Robert W.
Published: June 2017

Treatment with 10 μM taxol or 3 mM colchicine results in the development of similar aberrant morphotypes in Vicia hajastana (vetch) suspension cultures. After 2 days exposure to either drug, cells exhibit a disruption in polarity (i.e., swelling or spherical morphology). In taxol-treated cells, microtubules are abundant and brightly stained. In the presence of colchicine, microtubules are absent. Calcofluor staining illustrates that in the presence of taxol the microfibrils appear as thick ordered bundles, while in the presence of colchicine, microfibril bundles are smaller and exhibit less detectable order. The presence of thick bundles of microfibrils is confirmed in taxol-treated cells by the analysis of birefringence patterns. Walls of colchicine-treated cells exhibit a patchy birefringence pattern in polarized light, with adjacent patches exhibiting different order. Although taxol-treated cells contain abundant microtubules, their morphology and wall deposition resemble those of cells that lack microtubules. These observations indicate that the dynamics of microtubules may be important to their proper functioning in cell wall deposition. The differences in wall morphology between taxol- and colchicine-treated cells may reflect the different mechanisms of action of these two drugs.
Aspen and pine leaf litter decomposition in laboratory microcosms. II. Interactions of temperature and moisture level
Authors: Taylor Barry R. , Parkinson Dennis
Published: June 2017

To explore the relative influences of substrate type, temperature, and moisture on litter decomposition rates, leaf litter of aspen (Populus tremuloides Michx.) and pine (Pinus contorta Loud, × P. banksiana Lamb.) was decomposed in laboratory microcosms for 16 weeks at 2, 10, 18, and 26 °C and 15, 30, or 60 mL∙week−1 watering rate. Multiple regressions on mass remaining indicated temperature was a more important influence than watering rate for both species, but the degree and nature of response were different for pine compared with aspen. Decay rates of aspen were strongly affected by temperature and less so by watering rate, but pine decomposition was quite insensitive to both. For aspen, watering rate was a more important influence on decay rates at low temperatures (2 and 10 °C), while for pine it was more important at high temperatures (18 and 26 °C). There was a very strong interaction of time with temperature in the determination of aspen decomposition rate, but none for pine. All these differences are attributable to the disparate chemical and physical natures of the two litter types. The time × watering rate interaction was weak for both species, and there was no temperature × watering rate interaction at all. As a consequence of these differences in response to climatic variables, aspen leaves decomposed faster than pine needles under most conditions, but under cold, dry conditions pine decomposed faster than aspen.
Microsporogenesis in the normal and male-sterile stamenIess-2 mutant of tomato (Lycopersicon esculentum)
Authors: Sawhney V. K. , Bhadula S. K.
Published: June 2017

The development of microspores and the associated changes in the tapetum were examined in the normal (+/+) and male-sterile, stamenless-2 (sl-2/sl-2) mutant anthers of tomato (Lycopersicon esculentum). Anthers of eight comparable stages, from the microspore mother cell stage to anthesis, of both lines were processed for light microscopy. Until the formation of tetrads (stage ii), there were no differences in the sporogenous tissue, but the tapetal cells of the mutant were more enlarged than the normal and had, at places, divided to form a bilayer. Later, the tapetal cells in both lines became amoeboid and had sporopollenin-like deposits. At stage iv, whereas the tapetal cells of the normal had started to degenerate, those of the mutant were intact but had large vacuoles. Also at this stage, the deposition of exine was evident in normal microspores, but it was lacking in most mutant microspores, which enlarged considerably and eventually degenerated. From stage v onwards, the normal microspores progressed from the binucleate pollen to pollen containing many vacuoles to mature pollen. In the mutant, tapetum degeneration was delayed until stage v, and later, although some microspores closer to the tapetum appeared normal, most either were empty or had large vacuoles. It is suggested that the delay in tapetum degeneration coupled with the failure of exine deposition, presumably associated with low esterase activity, is responsible for pollen degeneration in the sl-2/sl-2 mutant.
Ophiodeira gen.nov. (Halosphaeriales) and a survey of higher marine fungi from Saint Croix (Virgin Islands)
Authors: Kohlmeyer Jan , Volkmann-Kohlmeyer Brigitte
Published: June 2017

The new monotypic genus, Ophiodeira, based on the lignicolous marine species O. monosemeia Kohlm. et Volkm.-Kohlm. sp.nov., is described and compared with the closely related Halosarpheia Kohlm. et Kohlm. The new species occurs on Rhizophora mangle in the Caribbean (Belize, Saint Croix, Tobago) and differs from other members of Halosphaeriaceae by a thin stroma, a curved neck, and a single ascospore appendage that develops into a long filament. A total of 35 higher marine fungi have been collected in Saint Croix on mangroves, coral reefs, and sandy beaches, comprising 31 ascomycetes, 2 basidiomycetes and 2 anamorphic fungi. All are new records for this island. New distributional data for several other Caribbean species are also listed. At present, 78 taxa of higher marine fungi are known from the tropical part of the western Atlantic Ocean.
Structure et ontogenèse du thalle squamuleux du lichen Endocarpon pusillum (Pyrénolichens, Verrucariacées)
Authors: Wagner Jean , Letrouit-Galinou Marie-Agnès
Published: June 2017

Observations concerning morphology, structure, and ontogeny of the thallus of a squamulous species, Endocarpon pusillum Hedw., are presented. The latter is composed of squamules, most of which are interconnected by a well developed network of rhizomorphs. Four types of squamules have been distinguished according to their morphological characters and their location with regard to rhizomorphs. The squamules of E. pusillum are characterized by the lack of lacunae and the presence of numerous rhizomorphic-like hyphae in the medulla, which are in topographical relation with the hyphae of the rhizomorphs. Morphological and structural data allowed us to follow an ontogenic continuum from the smallest squamules, i.e. the least differentiated, to the one bearing fruiting-bodies, which show numerous rhizomorphs.
Genera coelomycetum. XXV. Zetesimomyces anam. gen.nov.
Authors: Raj T. R. Nag
Published: June 2017

A new anamorph genus, Zetesimomyces, is proposed to accommodate a coelomycetous anamorph collected on leaf litter in Cuba and New Zealand.
Gradient analysis of remnant True and Upper Coastal Prairie grasslands of North America
Authors: Diamond David D. , Smeins Fred E.
Published: June 2017

Sixty-three upland True and Upper Coastal Prairie grasslands were sampled for vegetation composition and soil variables. The first axis from principal components analysis produced a south to north arrangement of stands along which temperature and precipitation decrease and soil organic matter increases (P < 0.0001). The second principal components analysis axis was related to a soils gradient, primarily within Texas communities, which had more varied soils than grasslands to the north. Species response curves against the first axis showed a continual replacement from north to south, with Schizachyrium scoparium and Paspalum plicatulum dominants in the south, Andropogon gerardii more important in central and northern communities, and Stipa spartea and Sporobolus heterolepis important in the north. The C3/C4 ratio of grasses increased rapidly northward from Nebraska. Species diversity and richness did not vary greatly and showed nonsignificant correlations with environmental variables across this latitudinal gradient. Stand relationships from cluster analysis corresponded with the results of principal components analysis, and based on these analyses, plus a review of the literature, seven community types were recognized. Five form a continuum, across which Andropogon gerardii increases northward and Schizachyrium scoparium increases southward, while two are limited to high-precipitation areas of north Texas.
Phénologie de la floraison de populations diploïdes et tétraploïdes d'Anthoxanthum alpinum et d'Anthoxanthum odoratum
Authors: Felber François
Published: June 2017

The phenology of flowering was studied in an experimental garden, on diploid and tetraploid populations of Anthoxanthum alpinum A. & D. Löve and of A. odoratum L. of central and southern Europe and also in situ in a contact zone between diploid A. alpinum and tetraploid A. odoratum. In the experimental garden, the phenological parameters were studied at the individual level (onset of flowering) and at the population level (dates on which each population showed opened anthers for the first time on 40, 50, 60, 70, or 80% of the plants). Anthoxanthum alpinum flowered earlier than A. odoratum, regardless of the respective ploidy level of the two taxa. The average time lag between the appearance of the stigma and that of the stamens was about 2 days for the two A. alpinum taxa and 6 days for those of A. odoratum. Flowering was spread over the longest period for the tetraploid A. odoratum, which shows the great phenological variability of this taxon. The in situ study confirms the precocity of A. alpinum. The phenological differentiation within this polyploid complex probably coincides with the individualization of the two diploid taxa but precedes their respective polyploidization phases.