33 research outputs found
Developing Literacy Learning Model Based on Multi Literacy, Integrated, and Differentiated Concept at Primary School
The main issue addressed in this research is the low writing skills of primary school students. One of the reasons for this condition is that the existing model of writing literacy learning is not appropriate. The purpose of this study is to explain MID-based literacy teaching model and the impact of the model in increasing primary school students\u27 writing skills. This study used combined methods of exploratory type. The samples were elementary school students coming from six schools with three different characteristics. Based on the data analysis, it can be concluded that the implementation of MID-based literacy learning model has proven to signi cantly contribute to the improvement of students\u27 writing skills. Taking place in all sample schools, the improvement may suggest that the model ts not only to students with high- ability but also those with low-ability. Therefore, the MID-based literacy learning model is needed to improve the ability to write various text types appropriately
Past and present distribution, densities and movements of blue whales <i>Balaenoptera musculus</i> in the Southern Hemisphere and northern Indian Ocean
1Blue whale locations in the Southern Hemisphere and northern Indian Ocean were obtained from catches (303 239), sightings (4383 records of =8058 whales), strandings (103), Discovery marks (2191) and recoveries (95), and acoustic recordings.2Sighting surveys included 7 480 450 km of effort plus 14 676 days with unmeasured effort. Groups usually consisted of solitary whales (65.2%) or pairs (24.6%); larger feeding aggregations of unassociated individuals were only rarely observed. Sighting rates (groups per 1000 km from many platform types) varied by four orders of magnitude and were lowest in the waters of Brazil, South Africa, the eastern tropical Pacific, Antarctica and South Georgia; higher in the Subantarctic and Peru; and highest around Indonesia, Sri Lanka, Chile, southern Australia and south of Madagascar.3Blue whales avoid the oligotrophic central gyres of the Indian, Pacific and Atlantic Oceans, but are more common where phytoplankton densities are high, and where there are dynamic oceanographic processes like upwelling and frontal meandering.4Compared with historical catches, the Antarctic (‘true’) subspecies is exceedingly rare and usually concentrated closer to the summer pack ice. In summer they are found throughout the Antarctic; in winter they migrate to southern Africa (although recent sightings there are rare) and to other northerly locations (based on acoustics), although some overwinter in the Antarctic.5Pygmy blue whales are found around the Indian Ocean and from southern Australia to New Zealand. At least four groupings are evident: northern Indian Ocean, from Madagascar to the Subantarctic, Indonesia to western and southern Australia, and from New Zealand northwards to the equator. Sighting rates are typically much higher than for Antarctic blue whales.6South-east Pacific blue whales have a discrete distribution and high sighting rates compared with the Antarctic. Further work is needed to clarify their subspecific status given their distinctive genetics, acoustics and length frequencies.7Antarctic blue whales numbered 1700 (95% Bayesian interval 860–2900) in 1996 (less than 1% of original levels), but are increasing at 7.3% per annum (95% Bayesian interval 1.4–11.6%). The status of other populations in the Southern Hemisphere and northern Indian Ocean is unknown because few abundance estimates are available, but higher recent sighting rates suggest that they are less depleted than Antarctic blue whales.</li
Incidence des puits sur la protection cathodique des plates-formes fixes
Les puits d'exploitation des gisements pétroliers onshore ne sont pas systématiquement protégés cathodiquement. Par contre les puits offshore supportés par les plates-formes fixes de forage sont nécessairement soumis aux systemes de protection cathodique destinés à celles-ci. La conception de ces systèmes doit prendre en compte la demande en courant des puits, considérée généralement comme parasite. Différentes méthodes de calcul existent, plus ou moins étayées par des considérations scientifiques. Aucune ne peut véritablement prévoir ce que sera la réalité et l'emploi de méthodes de mesure est nécessaire si l'on veut vérifier ce qui se passe exactement. Les différentes méthodes de calcul et de mesure sont passées en revue et critiquées, ce qui conduit à évoquer les points qui nous paraissent devoir être mieux étudiés dans le futur
Incidence des puits sur la protection cathodique des plates-formes fixes Influence of Welles on the Cathodic Protection of Fixed Platform
Les puits d'exploitation des gisements pétroliers onshore ne sont pas systématiquement protégés cathodiquement. Par contre les puits offshore supportés par les plates-formes fixes de forage sont nécessairement soumis aux systemes de protection cathodique destinés à celles-ci. La conception de ces systèmes doit prendre en compte la demande en courant des puits, considérée généralement comme parasite. Différentes méthodes de calcul existent, plus ou moins étayées par des considérations scientifiques. Aucune ne peut véritablement prévoir ce que sera la réalité et l'emploi de méthodes de mesure est nécessaire si l'on veut vérifier ce qui se passe exactement. Les différentes méthodes de calcul et de mesure sont passées en revue et critiquées, ce qui conduit à évoquer les points qui nous paraissent devoir être mieux étudiés dans le futur. Production wells on onshore cil fields are not systematically cathodically protected. On the contrary, offshore weils attained from fixed drilling plotforms are necessorily subjected to cathodic protection systems designed for such structures. The design of such systems must Cake into consideration the amount of current demanded by the well, generally considered as parositic current. Different colculoting methods exist, more or less based on scientific considerations. None con truly foresee what the reality will be, and measuring methods have ta be used if we want to check to see exactly what is happening. The different calculating and measuring methods are reviewed and criticized, thus bringing out points that we feel should be further investigated in the future
Effects of subsampling of passive acoustic recordings on acoustic metrics
Passive acoustic monitoring is an important tool in marine mammal studies. However, logistics and finances frequently constrain the number and servicing schedules of acoustic recorders, requiring a trade-off between deployment periods and sampling continuity, i.e., the implementation of a subsampling scheme. Optimizing such schemes to each project's specific research questions is desirable. This study investigates the impact of subsampling on the accuracy of two common metrics, acoustic presence and call rate, for different vocalization patterns (regimes) of baleen whales: (1) variable vocal activity, (2) vocalizations organized in song bouts, and (3) vocal activity with diel patterns. To this end, above metrics are compared for continuous and subsampled data subject to different sampling strategies, covering duty cycles between 50% and 2%. The results show that a reduction of the duty cycle impacts negatively on the accuracy of both acoustic presence and call rate estimates. For a given duty cycle, frequent short listening periods improve accuracy of daily acoustic presence estimates over few long listening periods. Overall, subsampling effects are most pronounced for low and/or temporally clustered vocal activity. These findings illustrate the importance of informed decisions when applying subsampling strategies to passive acoustic recordings or analyses for a given target species
Correction: Seasonal and Geographic Variation of Southern Blue Whale Subspecies in the Indian Ocean.
Seasonal and Geographic Variation of Southern Blue Whale Subspecies in the Indian Ocean
Understanding the seasonal movements and distribution patterns of migratory species over ocean basin scales is vital for appropriate conservation and management measures. However, assessing populations over remote regions is challenging, particularly if they are rare. Blue whales (Balaenoptera musculus spp) are an endangered species found in the Southern and Indian Oceans. Here two recognized subspecies of blue whales and, based on passive acoustic monitoring, four "acoustic populations" occur. Three of these are pygmy blue whale (B. m. brevicauda) populations while the fourth is the Antarctic blue whale (B. m. intermedia). Past whaling catches have dramatically reduced their numbers but recent acoustic recordings show that these oceans are still important habitat for blue whales. Presently little is known about the seasonal movements and degree of overlap of these four populations, particularly in the central Indian Ocean. We examined the geographic and seasonal occurrence of different blue whale acoustic populations using one year of passive acoustic recording from three sites located at different latitudes in the Indian Ocean. The vocalizations of the different blue whale subspecies and acoustic populations were recorded seasonally in different regions. For some call types and locations, there was spatial and temporal overlap, particularly between Antarctic and different pygmy blue whale acoustic populations. Except on the southernmost hydrophone, all three pygmy blue whale acoustic populations were found at different sites or during different seasons, which further suggests that these populations are generally geographically distinct. This unusual blue whale diversity in sub-Antarctic and sub-tropical waters indicates the importance of the area for blue whales in these former whaling grounds
Percentage of detected blue whale calls by location, call type and Southern Hemisphere season for the year 2007 (January to December).
<p>Spring (orange), Summer (red), Autumn (light blue), Winter (dark blue).</p
Passive stochastic matched filter for Antarctic blue whale call detection
As a first step to Antarctic blue whale (ABW) monitoring using passive acoustics, a method based on the stochastic matched filter (SMF) is proposed. Derived from the matched filter (MF), this filter-based denoising method enhances stochastic signals embedded in an additive colored noise by maximizing its output signal to noise ratio (SNR). These assumptions are well adapted to the passive detection of ABW calls where emitted signals are modified by the unknown impulse response of the propagation channel. A filter bank is computed and stored offline based on a priori knowledge of the signal second order statistics and simulated colored sea-noise. Then, the detection relies on online background noise and SNR estimation, realized using time-frequency analysis. The SMF output is cross-correlated with the signal's reference (SMF þ MF). Its performances are assessed on an ccean bottom seismometer-recorded ground truth dataset of 845 ABW calls, where the location of the whale is known. This dataset provides great SNR variations in diverse soundscapes. The SMF þ MF performances are compared to the commonly used MF and to the Z-detector (a sub-space detector for ABW calls). Mostly, the benefits of the use of the SMF þ MF are revealed on low signal to noise observations: in comparison to the MF with identical detection threshold, the false alarm rate drastically decreases while the detection rate stays high. Compared to the Z-detector, it allows the extension of the detection range of ' 30 km in presence of ship noise with equivalent false discovery rate.Imagerie mantellique du point chaud de La Réunio