Search results for "TLE"
showing 10 items of 2417 documents
Urbanization and forest degradation in east Africa - a case study around Dar es Salaam, Tanzania
2016
In this paper we examine the impact of the growing urbanization of Dar es Salaam, Tanzania, on the forest areas around the city. Since 1990 the city has seen an annual population growth rate of over 4%. We document the expansion of the city over the last 30 using the Global Human Settlement Layers, derived from the global Landsat archive. At the same time we show the depletion, of the surrounding forests that has occurred to meet the growing demand for agricultural land, fuel wood and construction material over the same period. The impact on these forests as a result of the demand from an expanding urban conglomeration is higher than would be expected from a dispersed population increase. T…
The binding of G-protein to rod outer segment phospholipids at the nitrogen–water interface
1989
In the visual process, one photoexcited rhodopsin (R*) catalyzes the activation of hundreds of G-proteins. It remains to be determined whether G-protein and R* find one another by membrane surface diffusion of these components (diffusion model) or by diffusion of G-protein through the aqueous phase (hopping model). A monolayer of each main rod outer segment (ROS) phospholipid interacting with a subphase containing G-protein, has been used to simulate the interaction of G-protein with the cytoplasmic surface of discal membranes. The possible diffusion of G-protein through the aqueous phase was then measured by observing its adsorption–desorption in the monolayer of each main ROS phospholipi…
Impact of human disturbance and beliefs on the tree agama Acanthocercus atricollis atricollis in a South African communal settlement
2009
We investigated the effects of human disturbance and attitudes on the density of the tree agama Acanthocercus atricollis atricollis in a densely populated rural settlement in South Africa. In this environment agamas live on trees that are harvested for firewood or maintained for fruit production. We conducted visual encounter surveys of A. a. atricollis and interviewed local households to establish whether human attitudes and actions could affect tree agama populations. Although local residents viewed tree agamas negatively (50% of interviewees claimed to have killed an agama) and acted to exclude them from their environment, tree agama density in villages was higher than that of adjacent c…
Energy use, diapause behaviour and northern range expansion potential in the invasive Colorado potato beetle
2011
Summary 1. As organisms expand their range towards northern latitudes they will encounter selective factors like harsh winter conditions. The ability to cope with and adapt to harsh winters may depend on the variability and evolutionary potential of relevant traits. 2. One adaptation in insects is winter diapause. It is characterized by changes in physiology, behaviour or in both. Physiological changes include lowered metabolic rate that enhances survival by saving limited energy reserves during overwintering. Active behavioural changes like burrowing into the soil allow individuals to escape harsh conditions. 3. We examined variation in overwintering body mass, resting metabolic rate (CO2 …
Feeding ecology of the loggerhead turtle Caretta caretta in the western Mediterranean
2001
We studied the feeding ecology of juvenile loggerhead turtles Caretta caretta in the western Mediterranean based on the contents of the digestive tract of 54 turtles (range of CCL: 34–69 cm) seized in Barcelona (Spain) in 1991. Turtles had been captured in fishing trawls, but specific information about dates and localities is not available. Despite this limitation, we obtained interesting evidences about the foraging strategies of loggerheads, with potentially important conservation implications. We report 33 new taxa in the diet. Results indicated that western Mediterranean loggerheads feed in an opportunistic way. Numerically, fish made up the most important prey group, followed by pelagi…
Gastrointestinal Helminths of Loggerhead Turtles (Caretta caretta) from the Western Mediterranean: Constraints on Community Structure
1998
Richness and composition of gastrointestinal helminth communities of 54 loggerhead turtles, Caretta caretta, from the western Mediterranean were interpreted from patterns of helminth exchange at 2 host taxonomic scales: exchange between marine turtles and other marine hosts and exchange within turtles. We predicted exchange of the former to be unimportant ecologically and evolutionarily because of the host phylogenetic distance. The absence of records of successful exchange at this host taxonomic scale confirmed that host physiological barriers seem to prevent contemporary parasite transfer between marine turtles and other sympatric hosts. Marine turtles also seem to exhibit an evolutionary…
New distributional data on <em>Haemogregarina stepanowi</em> (Apicomplexa) and <em>Placobdella costata</em> (Hirudinea) paras…
2021
The host-parasite system “Emys trinacris – Placobdella costata – Haemogregarina stepanowi” is known for Sicily, but scarce information is available to date about the distribution of the two parasites on the island. Therefore, an extensive sampling effort through visual census and collection and analysis of blood smears of the endemic Sicilian pond turtle E. trinacris was carried out in 46 water bodies scattered throughout mainland Sicily. Our findings revealed that the distribution of both parasites is limited to the Nebrodi area, where the infection of H. stepanowi has shown a high incidence on the local turtle populations. Our data suggest no correlation between the current distribution o…
Effect of lactoferrin addition on the dialysability of iron from infant formulas
2003
A possible enhancing effect of lactoferrin (Lf) on iron absorption by breast-fed infants has been suggested, however the available results failed to confirm this hypothesis. Nevertheless, Lf could be useful in protecting the lipid fraction of infant formulas against oxidation. Concerning the possibility of adding Lf to infant formulas with this aim, we considered it necessary to evaluate the effect of this addition on iron dialysability, which was used as a parameter indicator of bioavailability. An in vitro dialysability method was applied to three types of infant formulas, with and without Lf added, respectively. In none of the analysed formulas did the added Lf have a negative effect on …
Boat traffic in Lampedusa waters (Strait of Sicily, Mediterranean Sea) and its relation to the coastal distribution of common bottlenose dolphin (Tur…
2010
The volume of boat traffic and its potential connection to the coastal distribution of the common bottlenose dolphin (Tursiops truncatus) was evaluated off Lampedusa Island (Strait of Sicily). From July to September 2006 daily surveys were carried out at eight sites along the coast, three times a day, to assess the number, type, and size of boats moving, fishing, or stationed in Lampedusa waters. The study area was divided into four geographic areas: northwest, northeast, southwest, and southeast. Data were analyzed to determine the difference in the number of boats among the areas, sampling months, and times of day. The presence of dolphins was monitored by standardized land-based observat…
Effect of titanium (IV) application on some enzymatic activities in several developing stages of red pepper plants
1994
Abstract The effect of two titanium (IV) compounds, titanium ascorbate and titanium chloride, on some enzymatic activities, such as catalase, peroxidase, lipoxygenase and nitrate reductase in seeds, embryos, and seedlings and adult plants of red pepper (Capsicum annuum L.), was studied. A stimulatory effect of titanium was observed for every iron‐depending enzyme studied at all developing stages as well as for nitrate reductase but only for whole plants. This occurs because Ti+3/Ti+4 catalizes the activity of iron and enhances iron‐dependent enzymes.