ENSINANDO GEOMETRIA SEM O USO DE CALCULADORES: UM CASO EXPERIMENTAL EM APRENDIZES TAILANDESES DA 9ª SÉRIE

Should we solve geometry problems using calculators? This study identified the effect of using (and not using) calculators during calculations on geometry problems sets, as well as the perceived impact on the use of calculators based on students’, parents’ and school administrators’ perception in a school in Bangkok, Thailand. This study combined both qualitative (survey and interview) and quantitative techniques (experiment) to address the research problem. Findings revealed that the performance of students who used calculators in the experiment did not significantly differ with those who did not which suggests that non-usage of calculators will not affect solving geometry problems, at least in the context of Thai Math education. Further, survey showed that students only used calculators ‘sometimes’ outside class and gave diverse responses when asked why. Interview with parents, students and administrators showed transcript extracts mostly on their agreement to use calculators in geometry class citing the convenience and speed of doing problems but implied a negative impact on their academic performance in math problems in the real world. This study could provide a baseline information on the use of calculators in the teaching of Math lessons for other nationalities.Devemos resolver problemas de geometria usando calculadoras? Este estudo identificou o efeito do uso (ou não) de calculadoras durante cálculos em conjuntos de problemas de geometria, bem como o impacto percebido no uso de calculadoras com base na percepção de alunos, pais e administradores de escolas em uma escola em Bangkok, Tailândia . Este estudo combinou técnicas qualitativas (pesquisa e entrevista) e quantitativas (experimento) para abordar o problema de pesquisa. Os resultados revelaram que o desempenho dos alunos que usaram calculadoras no experimento não diferiu significativamente daqueles que não o fizeram, o que sugere que o não uso de calculadoras não afetará a resolução de problemas de geometria, pelo menos no contexto do ensino de matemática tailandês. Além disso, a pesquisa mostrou que os alunos só usavam calculadoras "às vezes" fora da classe e deram diversas respostas quando questionados sobre o motivo. Entrevistas com pais, alunos e administradores mostraram trechos de transcrição principalmente sobre sua concordância em usar calculadoras nas aulas de geometria, citando a conveniência e a velocidade de resolver os problemas, mas implicando um impacto negativo em seu desempenho acadêmico em problemas matemáticos no mundo real. Este estudo pode fornecer informações básicas sobre o uso de calculadoras no ensino de aulas de matemática para outras nacionalidades

Green Fluorescent Protein Labeling of Listeria, Salmonella, and Escherichia coli O157:H7 for Safety-Related Studies

Many food safety-related studies require tracking of introduced foodborne pathogens to monitor their fate in complex environments. The green fluorescent protein (GFP) gene (gfp) provides an easily detectable phenotype so has been used to label many microorganisms for ecological studies. The objectives of this study were to label major foodborne pathogens and related bacteria, including Listeria monocytogenes, Listeria innocua, Salmonella, and Escherichia coli O157:H7 strains, with GFP and characterize the labeled strains for stability of the GFP plasmid and the plasmid's effect on bacterial growth. GFP plasmids were introduced into these strains by a CaCl2 procedure, conjugation or electroporation. Stability of the label was determined through sequential propagation of labeled strains in the absence of selective pressure, and rates of plasmid-loss were calculated. Stability of the GFP plasmid varied among the labeled species and strains, with the most stable GFP label observed in E. coli O157:H7. When grown in nonselective media for two consecutive subcultures (ca. 20 generations), the rates of plasmid loss among labeled E. coli O157:H7, Salmonella and Listeria strains ranged from 0%–30%, 15.8%–99.9% and 8.1%–93.4%, respectively. Complete loss (>99.99%) of the plasmid occurred in some labeled strains after five consecutive subcultures in the absence of selective pressure, whereas it remained stable in others. The GFP plasmid had an insignificant effect on growth of most labeled strains. E. coli O157:H7, Salmonella and Listeria strains can be effectively labeled with the GFP plasmid which can be stable in some isolates for many generations without adversely affecting growth rates

Protection from ultraviolet damage and photocarcinogenesis by vitamin d compounds

© Springer Nature Switzerland AG 2020. Exposure of skin cells to UV radiation results in DNA damage, which if inadequately repaired, may cause mutations. UV-induced DNA damage and reactive oxygen and nitrogen species also cause local and systemic suppression of the adaptive immune system. Together, these changes underpin the development of skin tumours. The hormone derived from vitamin D, calcitriol (1,25-dihydroxyvitamin D3) and other related compounds, working via the vitamin D receptor and at least in part through endoplasmic reticulum protein 57 (ERp57), reduce cyclobutane pyrimidine dimers and oxidative DNA damage in keratinocytes and other skin cell types after UV. Calcitriol and related compounds enhance DNA repair in keratinocytes, in part through decreased reactive oxygen species, increased p53 expression and/or activation, increased repair proteins and increased energy availability in the cell when calcitriol is present after UV exposure. There is mitochondrial damage in keratinocytes after UV. In the presence of calcitriol, but not vehicle, glycolysis is increased after UV, along with increased energy-conserving autophagy and changes consistent with enhanced mitophagy. Reduced DNA damage and reduced ROS/RNS should help reduce UV-induced immune suppression. Reduced UV immune suppression is observed after topical treatment with calcitriol and related compounds in hairless mice. These protective effects of calcitriol and related compounds presumably contribute to the observed reduction in skin tumour formation in mice after chronic exposure to UV followed by topical post-irradiation treatment with calcitriol and some, though not all, related compounds

Impact of bacterial and fungal processes on C-14-hexadecane mineralisation in weathered hydrocarbon contaminated soil

In this study, the impact of bacterial and fungal processes on C-14-hexadecane mineralisation was investigated in weathered hydrocarbon contaminated soil. The extent of C-14-hexadecane mineralisation varied depending on the bioremediation strategy employed. Under enhanced natural attenuation conditions, C-14-hexadecane mineralisation after 98 days was 8.5 +/- 3.7% compared to <1.2% without nitrogen and phosphorus additions

Impact of bacterial and fungal processes on 14C-hexadecane mineralisation in weathered hydrocarbon contaminated soil

In this study, the impact of bacterial and fungal processes on 14 C-hexadecane mineralisation was investigated in weathered hydrocarbon contaminated soil. The extent of 14 C-hexadecane mineralisation varied depending on the bioremediation strategy employed. Under enhanced natural attenuation conditions, 14 C-hexadecane mineralisation after 98 days was 8.5± 3.7% compared to b1.2% without nitrogen and phosphorus additions

Assessment of five bioaccessibility assays for predicting the efficacy of petroleum hydrocarbon biodegradation in aged contaminated soils

In this study, the bioaccessibility of petroleum hydrocarbons in aged contaminated soils (1.6-67gkg -1) was assessed using four non-exhaustive extraction techniques (100% 1-butanol, 100% 1-propanol, 50% 1-propanol in water and hydroxypropyl-?-cyclodextrin) and the persulfate oxidation method. Using linear regression analysis, residual hydrocarbon concentrations following bioaccessibility assessment were compared to residual hydrocarbon concentrations following biodegradation in laboratory-scale microcosms in order to determine whether bioaccessibility assays can predict the endpoint of hydrocarbon biodegradation. The relationship between residual hydrocarbon concentrations following microcosm biodegradation and bioaccessibility assessment was linear (r 2=0.71-0.97) indicating that bioaccessibility assays have the potential to predict the extent of hydrocarbon biodegradation. However, the slope of best fit varied depending on the hydrocarbon fractional range assessed. For the C 10-C 14 hydrocarbon fraction, the slope of best fit ranged from 0.12 to 0.27 indicating that the non-exhaustive or persulfate oxidation methods removed 3.5-8 times more hydrocarbons than biodegradation. Conversely, for the higher molecular weight hydrocarbon fractions (C 29-C 36 and C 37-C 40), biodegradation removed up to 3.3 times more hydrocarbons compared to bioaccessibility assays with the resulting slope of best fit ranging from 1.0-1.9 to 2.0-3.3 respectivel

Assessing impediments to hydrocarbon biodegradation in weathered contaminated soils

In this study, impediments to hydrocarbon biodegradation in contaminated soils were assessed using chemical and molecular methodologies. Two long-term hydrocarbon contaminated soils were utilised which were similar in physico-chemical properties but differed in the extent of hydrocarbon (C10-C40) contamination (S1: 16.5 g kg-1; S2: 68.9 g kg-1). Under enhanced natural attenuation (ENA) conditions, hydrocarbon biodegradation was observed in S1 microcosms (26.4% reduction in C10-C40 hydrocarbons), however, ENA was unable to stimulate degradation in S2. Although eubacterial communities (PCR-DGGE analysis) were similar for both soils, the alkB bacterial community was less diverse in S2 presumably due to impacts associated with elevated hydrocarbons. When hydrocarbon bioaccessibility was assessed using HP-ß-CD extraction, large residual concentrations remained in the soil following the extraction procedure. However, when linear regression models were used to predict the endpoints of hydrocarbon degradation, there was no significant difference (P > 0.05) between HP-ß-CD predicted and microcosm measured biodegradation endpoints. This data suggested that the lack of hydrocarbon degradation in S2 resulted primarily from limited hydrocarbon bioavailability