85 research outputs found
THERMAL PERFORMANCE EVALUATION OF ROOM AIR CONDITIONERS EVAPORATORS
This work presents a thermal performance evaluation of a fin-and-tube evaporator - that is
widely used in packaged air conditioning equipment - using a balanced calorimeter
developed to simulate similar running conditions. The calorimeter determines the heat
rate absorbed by the evaporator, providing qualitative analysis of performance for a given
geometry. The calorimeter inside air is dried out due to the condensation process on the
evaporator under test during the transient period. By this way it is possible to preview the
humidity of the calorimeter domain and its influence with the instrumentation measurement.
The heat transfer rate absorbed by the evaporator is obtained by a lumped approach using
the energy conservation that is applied to the calorimeter domain, and is taken on the
boundaries of the equipment. Physical parameters such as overall heat transfer coefficient
for several types of fins can then be predicted in order to provide information for improving
the energy-efficiency-oriented design. The uncertainties are estimated by the propagation
of relative effects. Uncertainties are evaluated taking into account the systematic effects.
Results are shown in terms of evaporator overall heat transfer coefficient and heat transfer
rate as a function of inlet air temperature
Individual differences in second language speech learning in classroom settings: roles of awareness in the longitudinal development of Japanese learners’ English /ɹ/ pronunciation
The current study longitudinally examined a crucial individual difference variable—i.e., awareness (operationalized as explicit attention and articulatory knowledge)—in adult second language (L2) speech learning in the context of 40 Japanese learners’ English /ɹ/ pronunciation development in an EFL classroom. The participants’ speech, elicited from word reading, sentence reading and timed picture description tasks at the beginning and end of one academic semester, were analyzed in terms of three acoustic dimensions of English /ɹ/—third formant (F3), second formant (F2) and duration. Whereas the participants showed gains in the relatively easy aspect of the English /ɹ/ acquisition (F2 reduction) as a function of increased L2 input, their explicit awareness of accurate English /ɹ/ pronunciation played a significant role in the acquisition of the relatively difficult dimension (lengthening phonemic duration). The awareness-acquisition link was not found, however, for the most difficult dimension (F3 reduction) at least within the timeframe of the project
The role of input in second language oral ability development in foreign language classrooms: a longitudinal study
The current project longitudinally investigated the extent to which first-year Japanese university students developed their second language (L2) oral ability in relation to increased input in foreign language classrooms. Their spontaneous speech was elicited at the beginning, middle and end of one academic year, and then judged by linguistically trained coders for pronunciation, fluency, vocabulary and grammar qualities. According to the statistical analyses, the total amount of input (operationalized as number of English classes taken and L2 use outside of classrooms) was significantly related to the participants’ quick and immediate development of fluency and lexicogrammar during the first semester. Their pronunciation development was mixed, either subject to continuous change over two academic semesters (for prosody) or limited within the timeframe of the study (for segmentals). Similar to naturalistic L2 speech learning, the findings support the multifaceted role of input in different areas of oral proficiency development in foreign language classrooms
Native Speaker Perceptions of Accented Speech: The English Pronunciation of Macedonian EFL Learners
The paper reports on the results of a study that aimed to describe the vocalic and consonantal features of the English pronunciation of Macedonian EFL learners as perceived by native speakers of English and to find out whether native speakers who speak different standard variants of English perceive the same segments as non-native. A specially designed computer web application was employed to gather two types of data: a) quantitative (frequency of segment variables and global foreign accent ratings on a 5-point scale), and b) qualitative (open-ended questions). The result analysis points out to three most frequent markers of foreign accent in the English speech of Macedonian EFL learners: final obstruent devoicing, vowel shortening and substitution of English dental fricatives with Macedonian dental plosives. It also reflects additional phonetic aspects poorly explained in the available reference literature such as allophonic distributional differences between the two languages and intonational mismatch
Small molecule specifically inhibiting microglial nitric oxide release could become a potential treatment for neuroinflammation
Microglia are the immune effector cells of the central nervous system (CNS) and react to pathologic events with a complex process including the release of nitric oxide (NO). NO is a free radical, which is toxic for all cells at high concentrations. To target an exaggerated NO release, we tested a library of 16 544 chemical compounds for their effect on lipopolysaccharide (LPS)-induced NO release in cell line and primary neonatal microglia. We identified a compound (C1) which significantly reduced NO release in a dose-dependent manner, with a low IC50 (252 nM) and no toxic side effects in vitro or in vivo. Target finding strategies such as in silico modelling and mass spectroscopy hint towards a direct interaction between C1 and the nitric oxide synthase making C1 a great candidate for specific intra-cellular interaction with the NO producing machinery
Vowel reduction in word-final position by early and late Spanish-English bilinguals
Vowel reduction is a prominent feature of American English, as well as other stress-timed languages. As a phonological process, vowel reduction neutralizes multiple vowel quality contrasts in unstressed syllables. For bilinguals whose native language is not characterized by large spectral and durational differences between tonic and atonic vowels, systematically reducing unstressed vowels to the central vowel space can be problematic. Failure to maintain this pattern of stressed-unstressed syllables in American English is one key element that contributes to a ?foreign accent? in second language speakers. Reduced vowels, or ?schwas,? have also been identified as particularly vulnerable to the co-articulatory effects of adjacent consonants. The current study examined the effects of adjacent sounds on the spectral and temporal qualities of schwa in word-final position. Three groups of English-speaking adults were tested: Miami-based monolingual English speakers, early Spanish-English bilinguals, and late Spanish-English bilinguals. Subjects performed a reading task to examine their schwa productions in fluent speech when schwas were preceded by consonants from various points of articulation. Results indicated that monolingual English and late Spanish-English bilingual groups produced targeted vowel qualities for schwa, whereas early Spanish-English bilinguals lacked homogeneity in their vowel productions. This extends prior claims that schwa is targetless for F2 position for native speakers to highly-proficient bilingual speakers. Though spectral qualities lacked homogeneity for early Spanish-English bilinguals, early bilinguals produced schwas with near native-like vowel duration. In contrast, late bilinguals produced schwas with significantly longer durations than English monolinguals or early Spanish-English bilinguals. Our results suggest that the temporal properties of a language are better integrated into second language phonologies than spectral qualities. Finally, we examined the role of nonstructural variables (e.g. linguistic history measures) in predicting native-like vowel duration. These factors included: Age of L2 learning, amount of L1 use, and self-reported bilingual dominance. Our results suggested that different sociolinguistic factors predicted native-like reduced vowel duration than predicted native-like vowel qualities across multiple phonetic environments
Técnica de proteção cerebral na angioplastia e "stent" de carótida: um procedimento eficaz contra embolia
Surgical management of dural arteriovenous fistulas with transosseous arterial feeders involving the jugular bulb
Dural arteriovenous fistulas located in the vicinity of the jugular foramen are complex vascular malformations and belong to the most challenging skull base lesions to treat. The authors comprehensively analyze multiple features in a series of dural arteriovenous fistulas with transosseous arterial feeders involving the jugular bulb. Four patients who underwent surgery via the transcondylar approach to treat dural arteriovenous fistulas around the jugular foramen were retrospectively reviewed. Previously, endovascular treatment was attempted in all patients. The success of the surgical treatment was examined with postoperative angiography. Complete obliteration of the dural arteriovenous fistulas (DAVFs) was achieved in three patients, and significant flow reduction in one individual. All patients had a good postoperative outcome, and only one experienced mild hypoglossal nerve palsy. Despite extensive bone drilling, an occipitocervical fusion was necessary in only one patient with bilateral lesions. The use of an individually tailored transcondylar approach to treat dural arteriovenous fistulas at the region of the jugular foramen is most effective. This approach allows for complete obliteration of the connecting arterial feeders, and removal of bony structures containing pathological vessels
A Sound Approach to Language Matters: In Honor of Ocke-Schwen Bohn
The contributions in this Festschrift were written by Ocke’s current and former PhD-students, colleagues and research collaborators. The Festschrift is divided into six sections, moving from the smallest building blocks of language, through gradually expanding objects of linguistic inquiry to the highest levels of description - all of which have formed a part of Ocke’s career, in connection with his teaching and/or his academic productions: “Segments”, “Perception of Accent”, “Between Sounds and Graphemes”, “Prosody”, “Morphology and Syntax” and “Second Language Acquisition”. Each one of these illustrates a sound approach to language matters
- …