Some Misconceptions On Cell Structure And Function Held By A-Level Biology Students: Implications For Curriculum Development

A ZJER article on curriculum development.Knowledge about cell structure is vital in students' understanding of cell functions. It also plays a central role in their understanding of structure and function in organisms. This research is part of a bigger survey which analysed misconceptions held by students, teachers and those in commonly used Biology texts, with particular reference to misconceptions on cell structure and function. This paper reports on results obtained from open-ended questionnaires relating to A-level biology students’ misconceptions about cell structure. A total of 72 students participated in the study. The study revealed that some students hold misconceptions about cell structure and function that are likely to influence their understanding of other concepts if left un-addressed

Digital, statistical and wavelet study of turbulence flow structure in laboratory plunging water waves.

Ph. D. University of KwaZulu-Natal, Durban 2014.This dissertation presents an experimental investigation set out to study the evolution of turbulence in laboratory generated breaking water waves. The waves propagate and break as plunging waves on a 1:20 sloping beach. The aim of the study was to investigate the spatial and temporal evolution of the velocity field and subsequent turbulence structures induced by these plunging waves as they propagate along the flume. Experimental parameters measured included free surface elevations, wave height, mean water levels, wave phase velocity and synoptic measurements of fluid velocities for five accretive runs in the surf zone. Experimental data were analyzed using digital, statistical as well as wavelet approaches, in order to derive other turbulence quantities associated with the flow. The first set of experiments, performed in the vicinity of the break point, involved measuring the external flow characteristics of the breaker. This was done to get prior information about the breaking behaviour of the wave in terms of surface elevation, wave heights and wave velocities. 0.4 Hz monochromatic waves were generated in a glass-walled flume. A set of capacitive wave gauges were calibrated and then employed to record time series measurements of free surface elevations. Mean water levels, wave heights and phase velocities were then determined from the water level time series. Results show that as the wave propagates from deep water towards shallow water, there is an increase in the wave height, reaching a maximum height at the break point, and then decreases sharply thereafter. Cross correlation techniques were then used to determine the phase difference between the wave near the generator and the wave at various points along the flume. The local wave velocity was obtained by taking the phase difference between two points spaced 0.2 m apart. A comparison of the measured wave phase velocity, with linear shallow water and modified linear wave velocity approximations, is made at various points along the flume. The second set of experiments involved measuring internal flow parameters of the fluid. The experimental setup for this included a progressive scan digital camera (connected to a frame grabber inserted inside a computer) that was used to capture images of the breaking wave. The flow was seeded with neutrally buoyant, white polystyrene beads. The wave cycle was imaged using twenty fields of view or phases and 100 image pairs of the flow captured at each phase. A pair of strobe lights was used to illuminate the flow when capturing a pair of images which are spaced a few milliseconds apart. Thus, image pairs of the particle image field are captured with a set time interval. A video technique called digital correlation image velocimetry (DCIV) was used to analyze the images. With this method, image pairs were cross-correlated to determine particle displacements and thereby the instantaneous particle velocities. 100 instantaneous velocity flow fields spanning the entire water column including the aerated region were obtained at each phase. This enabled the quantification of the temporal and spatial evolution of the various turbulence parameters associated with the flow. Measurements were taken at five stations across the entire surf zone. Two-dimensional velocity flow fields are presented for phases where turbulence was observed to be predominant. The instantaneous velocities measured are up to two times the wave phase speed. The instantaneous velocity fields were then processed using phase-ensemble averaging to estimate the phase-averaged horizontal and vertical velocity fields and their corresponding fluctuating parts. Mean flow fields obtained by averaging 100 instantaneous flow fields at each phase, show the evolution of a shear layer between the nearly stagnant underlying fluid and the fast moving crest flow. Evolution of the stream-wise and along-shore profiles of the mean and turbulent quantities such as turbulence intensity, turbulent kinetic energy and vorticity of the flow are also presented. For this breaker, peak phase-ensemble averaged horizontal velocities were observed to be of the order of 250 cm/s while the vertical was about 50 cm/s. Measurements of the forward and reverse mass fluxes indicate a mean relative density for this plunging breaker to be around 0.44. Further statistical analysis yielded time-averaged mean horizontal and vertical velocities, root-mean-square (r.m.s) fluctuating velocities, turbulent kinetic energy and vorticity. Evolution results of these flow pa- rameters are also presented in the form of contour plots. Vertical and cross-variation of these turbulence characteristics are also presented for each of the chosen wave phases. Results show that most turbulence parameters appear to rise steadily from the trough, then rapidly, reaching peak values just above the still water line. They also show that a relatively large turbulent motion is initially organized in the crest of the breaking wave region. As the wave crest passes, this turbulent structure will then stretch downward to the lower interior region of the water column. Measurements of the time-averaged turbulence intensities and kinetic energy reveal that vertical profiles of these parameters increase from the flume bed up to a normalized elevation, z/h = 1.0. Thereafter, these parameters begin to decrease towards the crest. Peak turbulence parameters were observed near the front part of the wave crest with peak values of 0.11 and 0.06 for normalized horizontal and normalized vertical turbulence intensities, respectively. Froude-scaled turbulent kinetic energy was observed to increase almost linearly from the flume bed up to elevation z/h = 1.0. Both normalized, time-averaged turbulence intensity components and the Froude-scaled time-averaged turbulent kinetic energy results show nearly exponential decay towards the shore. Colour contour plots were used to visualize the evolution of vorticity as flow progressed. Instantaneous vorticity fields were observed to be characterized by patches of counter-rotating eddies. These pairs are generated at the free surface and translated as units in the direction of the flow. Eventually these high vorticity patches are observed to diffuse to the bottom of the flume reaching the flume bed after the crest has passed. While the phase speed is of the order of 150 cm/s, vortex structures were estimated to propagate with a speed of about 6 cm/s. Vorticity of the mean flow revealed a large vortex of peak value of around 150 s−1 developing around the shear boundary layer. The phenomenon of vortex shedding was observed in the evolution of mean flow vorticity where the tail of the initially strong shear layer vortex disintegrates as flow progresses. Finally, a continuous, one-dimensional, complex Morlet wavelet transform was applied to synthesized test signals comprising of three sinusoids of different frequencies. This was done to determine the relationship between the wavelet spatial scales and the period of the signal, from which a one-to-one relationship was obtained. The amount of energy available at each scale of the synthetic signals was then obtained and compared against the expected root-mean-square energy. This was done to calibrate the wavelet algorithm before it was used to extract the turbulent energy of the wave available in the velocity fluctuations. The wavelet energy was compared against the statistically calculated turbulent kinetic energy, and showed very good agreement at each phase, and at each elevation. The wavelet scales in the velocity fluctuations were then subdivided into three bands that are herein referred to as the micro, mid and macro scales. The wavelet energy spectrum of the flow shows that for the early phases of the flow, which correspond to the approach of the crest, up to 80 % of the wave energy is confined in the micro scales. For the remainder of the flow, micro scales contribute almost uniformly, about half of the maximum (40 %) shedding off excess energy which appears in the macro-scales. Mid scales were observed to contain 15 % of the total energy, almost uniformly throughout the wave cycle. Further energy analysis was performed to examine the variation of the total wavelet energy with scale at different phases of the flow. Results indicate that for phases corresponding to the approach of the crest, most of the energy lies in the micro-scales between 5 cm and 15 cm. The average wavelet energy at each phase of the flow was computed over several cycles at each elevation. Results show that for the three elevations considered, the micro-scales contain most of the energy while mid-scales have the least. The available energy of the wave decreases towards the shore

Analisis Karakteristik Antioksidan dalam Mister Kumis: Minuman Instan Serbuk Kulit Manggis ( Gar C Inia Mangostana L)

This research is aimed at finding out the antioxidant contents in instant drinkingpowder of mangosteen (Garcinia mangostana L) peel and finding out its preference level as antioxidant source. The method used in this research consisted of five steps, namely 1) makinginstant drinking powder of mangosteen peel (Garcinia mangostana L), 2) antioxidantcontent testing, 3) water content testing, 4) sugar content testing, 5) organoleptictesting. The result of the research on the antioxidant content of sample instantmangosteen peel drinking powder repeated twice with the average of 80 g of peel masswas 27.8350%, with the average 100 g of peel mass is 29.1237%, and with 120 g of peelmass was 31.7859%. Based on the result of organoleptic testing, most of therespondents preferred the sample with 120 g of the peel in terms of the taste, color,texture, and aroma

A Low Cost Concept for Data Acquisition Systems Applied to Decentralized Renewable Energy Plants

The present paper describes experiences of the use of monitoring and data acquisition systems (DAS) and proposes a new concept of a low cost DAS applied to decentralized renewable energy (RE) plants with an USB interface. The use of such systems contributes to disseminate these plants, recognizing in real time local energy resources, monitoring energy conversion efficiency and sending information concerning failures. These aspects are important, mainly for developing countries, where decentralized power plants based on renewable sources are in some cases the best option for supplying electricity to rural areas. Nevertheless, the cost of commercial DAS is still a barrier for a greater dissemination of such systems in developing countries. The proposed USB based DAS presents a new dual clock operation philosophy, in which the acquisition system contains two clock sources for parallel information processing from different communication protocols. To ensure the low cost of the DAS and to promote the dissemination of this technology in developing countries, the proposed data acquisition firmware and the software for USB microcontrollers programming is a free and open source software, executable in the Linux and Windows® operating systems

Leukocyte numbers and function in subjects eating n-3 enriched foods: selective depression of natural killer cell levels

Introduction While consumption of omega-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA) has been recommended for those at risk of inflammatory disease such as rheumatoid arthritis, the mechanism of their anti-inflammatory effect remains to be clearly defined, particularly in relation to the dose and type of n-3 LCPUFA. The objective of this study was to determine whether varying the levels of n-3 LCPUFA in erythrocyte membrane lipids, following dietary supplementation, is associated with altered numbers and function of circulating leukocytes conducive to protection against inflammation. Methods In a double-blind and placebo-controlled study, 44 healthy subjects aged 23 to 63 years consumed either standard or n-3 LCPUFA-enriched versions of typical processed foods, the latter allowing a target daily consumption of 1 gram n-3 LCPUFA. After six months, peripheral blood leukocyte and subpopulation proportions and numbers were assessed by flow cytometry. Leukocytes were also examined for lymphoproliferation and cytokine production, neutrophil chemotaxis, chemokinesis, bactericidal, adherence and iodination activity. Erythrocytes were analyzed for fatty-acid content. Results Erythrocyte n-3 LCPUFA levels were higher and absolute leukocyte and lymphocyte numbers were lower in subjects consuming n-3 enriched foods than in controls. There were no changes in the number of neutrophils, monocytes, T cells (CD3+), T-cell subsets (CD4+, CD8+) and B cells (CD19+). However, natural killer (NK) (CD3-CD16+CD56+) cell numbers were lower in n-3 supplemented subjects than in controls and were inversely related to the amount of eicosapentaenoic acid or docosahexaenoic acid in erythrocytes. No significant correlations were found with respect to lymphocyte lymphoproliferation and production of IFN-γ and IL-2, but lymphotoxin production was higher with greater n-3 LCPUFA membrane content. Similarly, neutrophil chemotaxis, chemokinesis, bactericidal activity and adherence did not vary with changes in erythrocyte n-3 LCPUFA levels, but the iodination reaction was reduced with higher n-3 LCPUFA content. Conclusion The data show that regular long-term consumption of n-3 enriched foods leads to lower numbers of NK cells and neutrophil iodination activity but higher lymphotoxin production by lymphocytes. These changes are consistent with decreased inflammatory reaction and tissue damage seen in patients with inflammatory disorders receiving n-3 LCPUFA supplementation.Violet R Mukaro, Maurizio Costabile, Karen J Murphy, Charles S Hii, Peter R Howe and Antonio Ferrant

The influence of intellectual capital on organizational performance

Intellectual capital is by far the most important factor in enhancing organizational performance. Companies require skilled workers who have the know-how, skills, experience, as well as the ability to bring new ideas for the success of the business. The contemporary economy is a knowledge-based economy, which means that information, knowledge, and other intangible assets are considered to be more valuable than physical commodities. The present research is aimed at investigating the connection between intellectual capital and organizational performance among the business sectors of Turkiye. The current research uses the current dataset of the business sectors of Turkey from 2009 to 2021. The Autoregressive Distributive Lag technique, which provides robust results on short-time period dataset, is employed to investigate this association. The present research differs from past studies in that it uses secondary data in analyzing the effect of human capital component of IC on firm performance, hence the originality of this research. Past research has widely examined the association of intellectual capital (IC) and firm performance with primary data. The major results of the present research show the importance of debt and equity finance in raising organizational performance. The results also show that long-term liability and intellectual capital reduce firm profitability. The present research gives crucial policy recommendations that are vital for policy making

Zinc and zinc transporters in macrophages and their roles in efferocytosis in COPD

Our previous studies have shown that nutritional zinc restriction exacerbates airway inflammation accompanied by an increase in caspase-3 activation and an accumulation of apoptotic epithelial cells in the bronchioles of the mice. Normally, apoptotic cells are rapidly cleared by macrophage efferocytosis, limiting any secondary necrosis and inflammation. We therefore hypothesized that zinc deficiency is not only pro-apoptotic but also impairs macrophage efferocytosis. Impaired efferocytic clearance of apoptotic epithelial cells by alveolar macrophages occurs in chronic obstructive pulmonary disease (COPD), cigarette-smoking and other lung inflammatory diseases. We now show that zinc is a factor in impaired macrophage efferocytosis in COPD. Concentrations of zinc were significantly reduced in the supernatant of bronchoalveolar lavage fluid of patients with COPD who were current smokers, compared to healthy controls, smokers or COPD patients not actively smoking. Lavage zinc was positively correlated with AM efferocytosis and there was decreased efferocytosis in macrophages depleted of Zn in vitro by treatment with the membrane-permeable zinc chelator TPEN. Organ and cell Zn homeostasis are mediated by two families of membrane ZIP and ZnT proteins. Macrophages of mice null for ZIP1 had significantly lower intracellular zinc and efferocytosis capability, suggesting ZIP1 may play an important role. We investigated further using the human THP-1 derived macrophage cell line, with and without zinc chelation by TPEN to mimic zinc deficiency. There was no change in ZIP1 mRNA levels by TPEN but a significant 3-fold increase in expression of another influx transporter ZIP2, consistent with a role for ZIP2 in maintaining macrophage Zn levels. Both ZIP1 and ZIP2 proteins were localized to the plasma membrane and cytoplasm in normal human lung alveolar macrophages. We propose that zinc homeostasis in macrophages involves the coordinated action of ZIP1 and ZIP2 transporters responding differently to zinc deficiency signals and that these play important roles in macrophage efferocytosis

Snatch loading of a single taut moored floating wave energy converter due to focussed wave groups

This paper concerns experimental measurements of the interaction of a taut moored floating body, representing a wave energy converter in survivability mode, with extreme waves. Focussed wave groups, based initially on NewWave theory, are used to generate the extreme waves, with crest amplitude exceeding the moorings design capacity. Two data sets are presented and discussed. In the first the influence of wave steepness on model response and mooring load is investigated using non-breaking focussed wave groups. In the second the influence of wave breaking location is investigated using a plunging breaking wave. Both data sets exhibit snatch loading as the extension of the mooring is exceeded. The magnitude of this loading is not found to be strongly dependent on wave steepness, while the following motion response of the body is. Breaking location has a much greater effect than wave steepness on the magnitude of the mooring load, while significant influence of the body motion and displacement on the mooring load is demonstrated. Evidence is provided that the use of individual focussed wave groups is inadequate to assess fully the extreme loads experienced by a taut moored WEC due to the demonstrated dependence of mooring load on the bodys motion and displacement

Genetic potential of tropically adapted exotic maize (Zea mays L.) heat-tolerant donor lines in sub-tropical breeding programs

Breeding for heat stress tolerance became a priority in sub-Saharan Africa (SSA), as projections are showing an increase in frequency, duration, and severity. In this study, 14 heat stress tolerant-donor lines (HSTDLs) sourced from CIMMYT-India (males) were crossed with 15 locally adapted elite lines (females) developed within the CIMMYT-Zimbabwe maize-breeding program using the North Carolina Design II mating scheme. The resultant 175 single crosses were evaluated alongside five commercial hybrids and adjacent to the trial of parental lines used in the crosses across two locations representing heat stress and optimal environments in Zimbabwe. The design II analysis showed significant (p < 0.01) general combining ability (GCA) effects for exotic heat donor lines and specific combining ability (SCA) effects on grain yield under heat stress, optimal conditions, and across locations; demonstrating additive and non-additive genetic inheritance of grain yield. High Baker’s ratios observed in this study indicate predominance of additive over non-additive gene effects. Three exotic HSTDLs, namely CAL14138, CAL152, and CAL1440, exhibited significant (p < 0.001) and positive GCA effects under heat stress conditions. The results imply that these exotic lines could serve as valuable genetic resources for introgression of heat tolerant alleles into local maize populations for accelerated yield genetic gains. Single crosses, DJ265-15 × VL1018816 and DJ267-9 × CAL1440, exhibited positive and significant (p < 0.01) and (p < 0.05) SCA effects for grain yield under heat stress conditions, respectively. These crosses can be used for further breeding and can contribute to grain yield performance under heat stress conditions. The exotic HSTDLs, CAL14138, CAL152, and VL109126 showed superior per se performance under heat, optimal conditions, and across environments. Overall data demonstrate the potential of exotic HSTDLs for improving the adaptation of maize to heat stress in sub-tropical breeding programs