834 research outputs found
Renewable sustainable biocatalyzed electricity production in a photosynthetic algal microbial fuel cell (PAMFC)
Electricity production via solar energy capturing by living higher plants and microalgae in combination with microbial fuel cells are attractive because these systems promise to generate useful energy in a renewable, sustainable, and efficient manner. This study describes the proof of principle of a photosynthetic algal microbial fuel cell (PAMFC) based on naturally selected algae and electrochemically active microorganisms in an open system and without addition of instable or toxic mediators. The developed solarpowered PAMFC produced continuously over 100 days renewable biocatalyzed electricity. The sustainable performance of the PAMFC resulted in a maximum current density of 539 mA/m2 projected anode surface area and a maximum power production of 110 mW/m2 surface area photobioreactor. The energy recovery of the PAMFC can be increased by optimization of the photobioreactor, by reducing the competition from non-electrochemically active microorganisms, by increasing the electrode surface and establishment of a further-enriched biofilm. Since the objective is to produce net renewable energy with algae, future research should also focus on the development of low energy input PAMFCs. This is because current algae production systems have energy inputs similar to the energy present in the outcoming valuable products
Learning L2 idioms in a CALL environment: The role of practice intensity, modality, and idiom properties
Idiomatic expressions like hit the road or turn the tables are known to be problematic for L2 learners, but research indicates that learning L2 idiomatic language is important. Relatively few studies, most of them focusing on English idioms, have investigated how L2 idioms are actually acquired and how this process is affected by important idiom properties like transparency (the degree to which the figurative meaning of an idiom can be inferred from its literal analysis) and cross-language overlap (the degree to which L2 idioms correspond to L1 idioms). The present study employed a specially designed CALL system to investigate the effects of intensity of practice and the reading modality on learning Dutch L2 idioms, as well as the impact of idiom transparency and cross-language overlap. The results show that CALL practice with a focus on meaning and form is effective for learning L2 idioms and that the degree of practice needed depends on the properties of the idioms. L2 learners can achieve or even exceed native-like performance. Practicing reading idioms aloud does not lead to significantly higher performance than reading idioms silently.These findings have theoretical implications as they show that differences between native speakers and L2 learners are due to differences in exposure, rather than to different underlying acquisition mechanisms. For teaching practice, this study indicates that a properly designed CALL system is an effective and an ecologically sound environment for learning L2 idioms, a generally unattended area in L2 classes, and that teaching priorities should be based on degree of transparency and cross-language overlap of L2 idioms
Normative data of Dutch idiomatic expressions: Subjective judgments you can bank on
The processing of idiomatic expressions is a topical issue in empirical research. Various factors have been found to influence idiom processing, such as idiom familiarity and idiom transparency. Information on these variables is usually obtained through norming studies. Studies investigating the effect of various properties on idiom processing have led to ambiguous results. This may be due to the variability of operationalizations of the idiom properties across norming studies, which in turn may affect the reliability of the subjective judgements. However, not all studies that collected normative data on idiomatic expressions investigated their reliability, and studies that did address the reliability of subjective ratings used various measures and produced mixed results. In this study, we investigated the reliability of subjective judgements, the relation between subjective and objective idiom frequency, and the impact of these dimensions on the participantsā idiom knowledge by collecting normative data of five subjective idiom properties (Frequency of Exposure, Meaning Familiarity, Frequency of Usage, Transparency, and Imageability) from 390 native speakers and objective corpus frequency for 374 Dutch idiomatic expressions. For reliability, we compared measures calculated in previous studies, with the D-coefficient, a metric taken from Generalizability Theory. High reliability was found for all subjective dimensions. One reliability metric, Krippendorffās alpha, generally produced lower values, while similar values were obtained for three other measures (Cronbachās alpha, Intraclass Correlation Coefficient, and the D-coefficient). Advantages of the D-coefficient are that it can be applied to unbalanced research designs, and to estimate the minimum number of raters required to obtain reliable ratings. Slightly higher coefficients were observed for so-called experience-based dimensions (Frequency of Exposure, Meaning Familiarity, and Frequency of Usage) than for content-based dimensions (Transparency and Imageability). In addition, fewer raters were required to obtain reliable ratings for the experience-based dimensions. Subjective and objective frequency appeared to be poorly correlated, while all subjective idiom properties and objective frequency turned out to affect idiom knowledge. Meaning Familiarity, Subjective and Objective Frequency of Exposure, Frequency of Usage, and Transparency positively contributed to idiom knowledge, while a negative effect was found for Imageability. We discuss these relationships in more detail, and give methodological recommendations with respect to the procedures and the measure to calculate reliability
Sex Differences in Semantic Processing: Event-Related Brain Potentials Distinguish between Lower and Higher Order Semantic Analysis during Word Reading
Behavioral studies suggest that women and men differ in the strategic elaboration of verbally encoded information especially in the absence of external task demand. However, measuring such covert processing requires other than behavioral data. The present study used event-related potentials to compare sexes in lower and higher order semantic processing during the passive reading of semantically related and unrelated word pairs. Women and men showed the same early context effect in the P1-N1 transition period. This finding indicates that the initial lexical-semantic access is similar in men and women. In contrast, sexes differed in higher order semantic processing. Women showed an earlier and longer lasting context effect in the N400 accompanied by larger signal strength in temporal networks similarly recruited by men and women. The results suggest that women spontaneously conduct a deeper semantic analysis. This leads to faster processing of related words in the active neural networks as reflected in a shorter stability of the N400 map in women. Taken together, the findings demonstrate that there is a selective sex difference in the controlled semantic analysis during passive word reading that is not reflected in different functional organization but in the depth of processin
Glioma infiltration of the corpus callosum: early signs detected by DTI
The most frequent primary brain tumors, anaplastic astrocytomas (AA) and glioblastomas (GBM): tend to invasion of the surrounding brain. Histopathological studies found malignant cells in macroscopically unsuspicious brain parenchyma remote from the primary tumor, even affecting the contralateral hemisphere. In early stages, diffuse interneural infiltration with changes of the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) is suspected. The purpose of this study was to investigate the value of DTI as a possible instrument of depicting evidence of tumor invasion into the corpus callosum (CC). Preoperatively, 31 patients with high-grade brain tumors (8 AA and 23 GBM) were examined by MRI at 3Ā T, applying a high-resolution diffusion tensor imaging (DTI) sequence. ADC- and FA-values were analyzed in the tumor-associated area of the CC as identified by fiber tracking, and were compared to matched healthy controls. In (MR-)morphologically normal appearing CC the ADC values were elevated in the tumor patients (nĀ =Ā 22; 0.978Ā ĆĀ 10(ā3)Ā mmĀ²/s) compared to matched controls (0.917Ā ĆĀ 10(ā3)Ā mmĀ²/s, pĀ <Ā 0.05), and the corresponding relative FA was reduced (rFA: 88Ā %, pĀ <Ā 0.01). The effect was pronounced in case of affection of the CC visible on MRI (nĀ =Ā 9; 0.978Ā ĆĀ 10(ā3)Ā mmĀ²/s, pĀ <Ā 0.05; rFA: 72Ā %, pĀ <Ā 0.01). Changes in diffusivity and anisotropy in the CC can be interpreted as an indicator of tumor spread into the contralateral hemisphere not visible on conventional MRI
Neoplastic Meningitis: How MRI and CSF Cytology Are Influenced by CSF Cell Count and Tumor Type
Background. Although CSF cytology and MRI are standard methods to diagnose neoplastic meningitis (NM), this complication of neoplastic disease remains difficult to detect. We therefore reevaluated the sensitivity of gadolinium (GD)-enhanced MRI and cerebrospinal-fluid (CSF)-cytology and the relevance of tumor type and CSF cell count. Methods. We retrospectively identified 111 cases of NM diagnosed in our CSF laboratory since 1990 with complete documentation of both MRI and CSF cytology. 37 had haematological and 74 solid neoplasms. CSF cell counts were increased in 74 and normal in 37 patients. Results. In hematological neoplasms, MRI was positive in 49% and CSF cytology in 97%. In solid tumors, the sensitivity of MRI was 80% and of cytology 78%. With normal CSF cell counts, MRI was positive in 59% (50% hematological, 72% solid malignancies) and CSF cytology in 76% (92% in hematological, 68% in solid neoplasms). In cases of elevated cell counts, the sensitivity of MRI was 72% (50% for hematological, 83% for solid malignancies) and of CSF cytology 91% (100% for haematological and 85% for solid neoplasms). 91% of cytologically positive cases were diagnosed at first and another 7% at second lumbar puncture. Routine protein analyses had a low sensitivity in detecting NM. Conclusions. The high overall sensitivity of MRI was only confirmed for NM from solid tumors and for elevated CSF cell counts. With normal cell counts and haematological neoplasms, CSF-cytology was superior to MRI. None of the analysed routine CSF proteins had an acceptable sensitivity and specificity in detecting leptomeningeal disease
Comparison of laser Doppler flowmetry and thermometry in the postoperative monitoring of replantations
Reliable postoperative monitoring in microvascular surgery is necessary to improve the success rate of reexplorations following vascular compromise. Surface thermometry is known as an easy and inexpensive objective postoperative monitor and therefore is used by many microsurgeons. Reliability, however, is not satisfactory, and therefore several other instrumental methods have been tested of which laser Doppler flowmetry shows the most promising results. This study compared laser Doppler flowmetry to thermometry in the postoperative monitoring after replantation surgery. In 34 patients, 45 replantations and revascularizations were monitored by laser Doppler flowmetry and thermometry. A reliable alarm value of 10 PU was defined for replantations and revascularizations, with a sensitivity of 93% and a specificity of 94%. Thermometry showed a sensitivity of 84% and a specificity of 86% at 29Ā°C
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Weed Management Practices for Organic Production of Trailing Blackberry, II. Accumulation and Loss of Biomass and Nutrients
A study was conducted in western Oregon to assess the impact of cultivar and weed management strategy on accumulation and loss of plant biomass and nutrients during the first 3 years of establishment when using organic fertilizer. The study was conducted in trailing blackberry (Rubus L. subgenus Rubus Watson) planted in May 2010 and certified organic in May 2012. Treatments included two cultivars, Marion and Black Diamond, each with either no weed control after the first year after planting or with weeds managed by hand-weeding or the use of weed mat. Each treatment was amended with organically approved fertilizers at pre-plant and was drip-fertigated with fish emulsion each spring. Most primocane leaf nutrient concentrations were within the range recommended for blackberry. However, leaf nitrogen (N) was low in āBlack Diamondā, especially when grown without weed control, whereas leaf boron (B) was low in all treatments. In many cases, leaf nutrient concentrations were affected by cultivar and weed management in both the primocanes and the floricanes. The concentration of several nutrients in the fruit differed between cultivars, including calcium (Ca), magnesium (Mg), sulfur (S), B, and zinc (Zn), but only fruit Ca was affected by weed management and only in āMarionā. In this case, fruit Ca was higher when the cultivar was grown with weed mat than with hand-weeding or no weeding. Total biomass production of primocanes increased from an average of 0.3 tĀ·haā»Ā¹ dry weight (DW) during the first year after planting to 2.0 tĀ·haā»Ā¹ DW the next year. Plants were first cropped the third year after planting and gained an additional 3.3 tĀ·haā»Ā¹ DW in total aboveground biomass (primocanes, floricanes, and fruit) by the end of the third season. Fruit DW averaged 1.4 tĀ·haā»Ā¹ in non-weeded plots, 1.9 tĀ·haā»Ā¹ in hand-weeded plots, and 2.3 tĀ·haā»Ā¹ in weed mat plots. Biomass of senesced floricanes (removed after harvest) averaged 3.2 tĀ·haā»Ā¹ DW and was similar between cultivars and among the weed management treatments. āMarionā primocanes accumulated a higher content of N, phosphorus (P), potassium(K), Mg, S, iron (Fe), B, copper (Cu), and aluminum (Al) than in āBlack Diamondā. Weeds, however, reduced nutrient accumulation in the primocanes in both cultivars, and accumulation of nutrients was greater in the floricanes than in the previous yearās primocanes. Total nutrient content declined from June to August in the floricanes, primarily through fruit removal at harvest and senescence of the floricanes after harvest. Depending on the cultivar and weed management strategy, nutrient loss from the fruit and floricanes averaged 34 to 79 kgĀ·haā»Ā¹ of N, 5 to 12 kgĀ·haā»Ā¹ of P, 36 to 84 kgĀ·haā»Ā¹ of K, 23 to 61 kgĀ·haā»Ā¹ of Ca, 5 to 15 kgĀ·haā»Ā¹ of Mg, 2 to 5 kgĀ·haā»Ā¹ of S, 380 to 810 gĀ·haā»Ā¹ of Fe, 70 to 300 gĀ·haā»Ā¹ of B, 15 to 36 gĀ·haā»Ā¹ of Cu, 610 to 1350 gĀ·haā»Ā¹ of manganese (Mn), 10 to 260 gĀ·haā»Ā¹ of Zn, and 410 to 950 gĀ·haā»Ā¹ of Al. Overall, plants generally accumulated (and lost) the most biomass and nutrients with weed mat and the least with no weed control.This is the publisherās final pdf. The published article is copyrighted by the American Society for Horticultural Science and can be found at: http://hortsci.ashspublications.org/.Keywords: Tissue nutrient status weed control, Organic fertilizer, Rubus, Landscape fabri
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