943 resultados para semiarid typical grassland


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Self-recognition has been explored in nonlinguistic organisms by recording whether individuals touch a dye-marked area on visually inaccessible parts of their face while looking in a mirror or inspect parts of their body while using the mirror's reflection. Only chimpanzees, gorillas, orangutans, and humans over the age of approximately 2 years consistently evidence self-directed mirror-guided behavior without experimenter training. To evaluate the inferred phylogenetic gap between hominoids and other animals, a modified dye-mark test was conducted with cotton-top tamarins (Saguinus oedipus), a New World monkey species. The white hair on the tamarins' head was color-dyed, thereby significantly altering a visually distinctive species-typical feature. Only individuals with dyed hair and prior mirror exposure touched their head while looking in the mirror. They looked longer in the mirror than controls, and some individuals used the mirror to observe visually inaccessible body parts. Prior failures to pass the mirror test may have been due to methodological problems, rather than to phylogenetic differences in the capacity for self-recognition. Specifically, an individual's sensitivity to experimentally modified parts of its body may depend crucially on the relative saliency of the modified part (e.g., face versus hair). Moreover, and in contrast to previous claims, we suggest that the mirror test may not be sufficient for assessing the concept of self or mental state attribution in nonlinguistic organisms.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This dissertation examines the role of topic knowledge (TK) in comprehension among typical readers and those with Specifically Poor Comprehension (SPC), i.e., those who demonstrate deficits in understanding what they read despite adequate decoding. Previous studies of poor comprehension have focused on weaknesses in specific skills, such as word decoding and inferencing ability, but this dissertation examined a different factor: whether deficits in availability and use of TK underlie poor comprehension. It is well known that TK tends to facilitate comprehension among typical readers, but its interaction with working memory and word decoding is unclear, particularly among participants with deficits in these skills. Across several passages, we found that SPCs do in fact have less TK to assist their interpretation of a text. However, we found no evidence that deficits in working memory or word decoding ability make it difficult for children to benefit from their TK when they have it. Instead, children across the skill spectrum are able to draw upon TK to assist their interpretation of a passage. Because TK is difficult to assess and studies vary in methodology, another goal of this dissertation was to compare two methods for measuring it. Both approaches score responses to a concept question to assess TK, but in the first, a human rater assigns a score whereas in the second, a computer algorithm, Latent Semantic Analysis (LSA; Landauer & Dumais, 1997) assigns a score. We found similar results across both methods of assessing TK, suggesting that a continuous measure is not appreciably more sensitive to variations in knowledge than discrete human ratings. This study contributes to our understanding of how best to measure TK, the factors that moderate its relationship with recall, and its role in poor comprehension. The findings suggest that teaching practices that focus on expanding TK are likely to improve comprehension across readers with a variety of abilities.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The aim of this paper is to obtain a comprehensive picture of the importance of the fish fauna in the wetlands and coastal lagoons of the Bajo Vinalopó region (Alicante, South eastern Spain) and the ecological, historical and cultural value of the traditional knowledge on fishing maintained by local people. We have compiled data from different information sources: (1) the revision of historical archives, (2) personal interviews and collaborative research, and (3) ecological and water quality data. The results show that the area sustains important fish fauna diversity (17 species) and that local people have inherited a considerable traditional knowledge on fishing methods (11 modalities), on the maintenance and sound management of the water system and on the ecology and behaviour of fish. We conclude that a comprehensive consideration of all these ecological, historical and socio-cultural aspects related to fish and fishing shows clearly the value of this ecological and cultural heritage and provides a necessary base for a sustainable management of the area.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

After the 2010 Haiti earthquake, that hits the city of Port-au-Prince, capital city of Haiti, a multidisciplinary working group of specialists (seismologist, geologists, engineers and architects) from different Spanish Universities and also from Haiti, joined effort under the SISMO-HAITI project (financed by the Universidad Politecnica de Madrid), with an objective: Evaluation of seismic hazard and risk in Haiti and its application to the seismic design, urban planning, emergency and resource management. In this paper, as a first step for a structural damage estimation of future earthquakes in the country, a calibration of damage functions has been carried out by means of a two-stage procedure. After compiling a database with observed damage in the city after the earthquake, the exposure model (building stock) has been classified and through an iteratively two-step calibration process, a specific set of damage functions for the country has been proposed. Additionally, Next Generation Attenuation Models (NGA) and Vs30 models have been analysed to choose the most appropriate for the seismic risk estimation in the city. Finally in a next paper, these functions will be used to estimate a seismic risk scenario for a future earthquake.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The “dehesa” (grassland with scattered oak trees) is a typical Mediterranean ecosystem from west Iberian Peninsula that has resulted from the transformation of the forest by clearing and brushwood removing and the landscape is maintained mainly bulls and/or Iberian pigs. This ecosystem is characterized by the presence of old scattered trees that are considered as “keystone-structures”, which favor the presence of a wide range of biodiversity, especially those species that are wood-dependent (saproxylic insects). Saproxylics are a diversified group involved in the recycling process of nutrients in forest, and thus they are considered as a bioindicator group of the quality and conservation status of habitats, including a wide number of species under some categories of threat according the IUCN criteria. It is widely recognized the importance of studying the main factors that determine the structure and distribution of species assemblages at both spatial and temporal scales, nevertheless, the saproxylic assemblages has been poorly studied from the temporal dimension. With this study we provide knowledge about the effect of the “dehesa” heterogeneity, species seasonality and distribution on this habitat and we highlight the importance of the maintaining of traditional practices as a tool for saproxylic insect diversity and conservation.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

In early spring the Baltic region is frequently affected by high-pollution events due to biomass burning in that area. Here we present a comprehensive study to investigate the impact of biomass/grass burning (BB) on the evolution and composition of aerosol in Preila, Lithuania, during springtime open fires. Non-refractory submicron particulate matter (NR-PM1) was measured by an Aerodyne aerosol chemical speciation monitor (ACSM) and a source apportionment with the multilinear engine (ME-2) running the positive matrix factorization (PMF) model was applied to the organic aerosol fraction to investigate the impact of biomass/grass burning. Satellite observations over regions of biomass burning activity supported the results and identification of air mass transport to the area of investigation. Sharp increases in biomass burning tracers, such as levoglucosan up to 683 ngm-3 and black carbon (BC) up to 17 μgm-3 were observed during this period. A further separation between fossil and non-fossil primary and secondary contributions was obtained by coupling ACSM PMF results and radiocarbon (14C) measurements of the elemental (EC) and organic (OC) carbon fractions. Non-fossil organic carbon (OCnf/ was the dominant fraction of PM1, with the primary (POCnf/ and secondary (SOCnf/ fractions contributing 26–44% and 13–23% to the total carbon (TC), respectively. 5–8% of the TC had a primary fossil origin (POCf/, whereas the contribution of fossil secondary organic carbon (SOCf/ was 4–13 %. Nonfossil EC (ECnf/ and fossil EC (ECf/ ranged from 13–24 and 7–13 %, respectively. Isotope ratios of stable carbon and nitrogen isotopes were used to distinguish aerosol particles associated with solid and liquid fossil fuel burning.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

There have been many studies pertaining to the management of herpetic meningoencephalitis (HME), but the majority of them have focussed on virologically unconfirmed cases or included only small sample sizes. We have conducted a multicentre study aimed at providing management strategies for HME. Overall, 501 adult patients with PCR-proven HME were included retrospectively from 35 referral centres in 10 countries; 496 patients were found to be eligible for the analysis. Cerebrospinal fluid (CSF) analysis using a PCR assay yielded herpes simplex virus (HSV)-1 DNA in 351 patients (70.8%), HSV-2 DNA in 83 patients (16.7%) and undefined HSV DNA type in 62 patients (12.5%). A total of 379 patients (76.4%) had at least one of the specified characteristics of encephalitis, and we placed these patients into the encephalitis presentation group. The remaining 117 patients (23.6%) had none of these findings, and these patients were placed in the nonencephalitis presentation group. Abnormalities suggestive of encephalitis were detected in magnetic resonance imaging (MRI) in 83.9% of the patients and in electroencephalography (EEG) in 91.0% of patients in the encephalitis presentation group. In the nonencephalitis presentation group, MRI and EEG data were suggestive of encephalitis in 33.3 and 61.9% of patients, respectively. However, the concomitant use of MRI and EEG indicated encephalitis in 96.3 and 87.5% of the cases with and without encephalitic clinical presentation, respectively. Considering the subtle nature of HME, CSF HSV PCR, EEG and MRI data should be collected for all patients with a central nervous system infection.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Aims The relationship between biodiversity and ecosystem functioning is among the most active areas of ecological research. Furthermore, enhancing the diversity of degraded ecosystems is a major goal in applied restoration ecology. In grasslands, many species may be locally absent due to dispersal or microsite limitation and may therefore profit from mechanical disturbance of the resident vegetation. We established a seed addition and disturbance experiment across several grassland sites of different land use to test whether plant diversity can be increased in these grasslands. Additionally, the experiment will allow us testing the consequences of increased plant diversity for ecosystem processes and for the diversity of other taxa in real-world ecosystems. Here we present details of the experimental design and report results from the first vegetation survey one year after disturbance and seed addition. Moreover, we tested whether the effects of seed addition and disturbance varied among grassland depending on their land use or pre-disturbance plant diversity. Methods A full-factorial experiment was installed in 73 grasslands in three regions across Germany. Grasslands were under regular agricultural use, but varied in the type and the intensity of management, thereby representing the range of management typical for large parts of Central Europe. The disturbance treatment consisted of disturbing the top 10 cm of the sward using a rotavator or rotary harrow. Seed addition consisted of sowing a high-diversity seed mixture of regional plant species. These species were all regionally present, but often locally absent, depending on the resident vegetation composition and richness of each grassland. Important findings One year after sward disturbance it had significantly increased cover of bare soil, seedling species richness and numbers of seedlings. Seed addition had increased plant species richness, but only in combination with sward disturbance. The increase in species richness, when both seed addition and disturbance was applied, was higher at high land-use intensity and low resident diversity. Thus, we show that at least the early recruitment of many species is possible also at high land-use intensity, indicating the potential to restore and enhance biodiversity of species-poor agricultural grasslands. Our newly established experiment provides a unique platform for broad-scale research on the land-use dependence of future trajectories of vegetation diversity and composition and their effects on ecosystem functioning.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

National Highway Traffic Safety Administration, Washington, D.C.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Includes index.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

National Highway Traffic Safety Administration, Washington, D.C.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Cover title.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

"The issue is limited to two hundred and fifty copies."