Immediate effects of selective logging on the feeding guilds and species composition of understorey birds in Ulu Muda Forest Reserve, Peninsular Malaysia.

A study was conducted in a hill dipterocarp forest covering an area of 791.2 ha in Ulu Muda Forest Reserve, Kedah, Peninsular Malaysia. It was logged using selective logging method in February 1998 and completed in December 2000. The objective of this study was to determine the changes in the feeding guild structures of the understorey bird species before and immediately after logging using mist-netting method. Results indicated that before the forest was logged 72.4% of the number of understorey birds were dominated by insectivore followed by insectivore/frugivore (18.2%) and nectarivore/insectivore/frugivore groups (4.1%). However, immediately after the forest was logged the insectivore/frugivore became the dominant group (47.3%) followed by insectivore (28.5%) and nectarivore/insectivore/frugivore groups (13.2%). Analysis of feeding guild also showed that before logging the forest was dominated mainly by the species that belong to arboreal foliage gleaning insectivore guild (30.0%) and it decreased to 26.5% immediately after logging. In terms of number of individuals, the insectivore recorded 123 individuals (46 species) before logging, compared to only 106 individuals (37 species) immediately after logging. The arboreal foliage gleaning insectivore/frugivore was found to be higher in terms of number of species (17 species; 25.0%) and individuals (176 individuals; 47.3%) immediately after logging. Only 20.0% (14 species) of the species and 18.2% (31 individuals) of individuals from the guild were recorded before logging. Therefore, this study indicated that logging changed the feeding guild structures of the understorey bird species. Alteration of the food sources and microclimate of the logged forest has been suggested to be the main causes for the changes in the feeding guild structures

Numerical Investigations on the Port Flow Field of a Two-Stroke Poppet Valve Engine

This paper describes the model and simulation results of port flow field investigations on a two-stroke poppet valve engine. Higher power to weight ratio has been the advantage of a two-stroke engine over the four-stroke engine. However, poor emissions have plagued two-stroke ported design which is the main design mass produced for small engines. By employing poppet valve configuration, the gas exchange performance, hence the emissions can be improved. In order to verify this, two-dimensional (2D) and three-dimensional models of the two-stroke poppet valve engine are developed to illustrate the port flow field with the proposed valve timings obtained from the one-dimensional numerical analysis. Several design changes on the cylinder are proposed and investigated through the simulation. Further insight into the fluid mechanics of the flow into the engine can be provided by examining the in-cylinder velocity flow fields. The 2D simulation results have shown that by having a shroud on the inlet valve, the short-circuiting can be minimised without any modification on the cylinder head. Further, the 3D simulation results have shown sufficient swirl occurs in the cylinder but the tumble flow is not apparent

Edge effects on foraging guilds of upperstory birds in an isolated tropical rainforest of Malaysia

The forest edge is the boundary between the forest area and the surrounding landscape. In this study forest edge is surrounded landscape which encompass of housing societies, highway, sports complex and equestrian park. Edge may directly or indirectly affect bird species in forest habitats because of various microclimate conditions (i.e., sunlight, wind, temperature, relative humidity) and microhabitat factors (i.e., vegetation species composition, structure and food resources). However, little information is available on the effects of edge on tropical forest birds. This study was conducted in an isolated tropical rainforest from March 2010 to June 2011 using a distance sampling point count technique to examine edge effects on the foraging guilds of upperstory bird species. In total, 1,618 individuals representing 61 upperstory bird species were detected. The analysis of feeding guilds indicated that sallying insectivores (F6 = 22.95, P < 0.001), arboreal foliage-gleaning frugivores (F6 = 3.87, P < 0.001) and arboreal foliage-gleaning insectivore/frugivores (F6 = 4.42, P < 0.001) showed a significant difference in habitat selection at different distances from the edge to the interior of the forest. This finding shows that changes in the micro-environment have a significant effect on the distribution and richness of upperstory birds. This study demonstrated that the large-sized upperstory bird species, such as barbets, broadbills and malkohas tend to forage at the forest interior and infrequently observed at the forest edge. The study also showed that the upperstory bird species were influenced by the forest edge due to factors related to microclimate. However, the response of upperstory bird species may vary from species to species and from the forest edge to the interior. The birds selected specific microhabitat and microclimate characteristics that offered optimal food, shelter and breeding sites

Edge effects on foraging guilds of upperstory birds in an isolated tropical rainforest of Malaysia

The forest edge is the boundary between the forest area and the surrounding landscape. In this study forest edge is surrounded landscape which encompass of housing societies, highway, sports complex and equestrian park. Edge may directly or indirectly affect bird species in forest habitats because of various microclimate conditions (i.e., sunlight, wind, temperature, relative humidity) and microhabitat factors (i.e., vegetation species composition, structure and food resources). However, little information is available on the effects of edge on tropical forest birds. This study was conducted in an isolated tropical rainforest from March 2010 to June 2011 using a distance sampling point count technique to examine edge effects on the foraging guilds of upperstory bird species. In total, 1,618 individuals representing 61 upperstory bird species were detected. The analysis of feeding guilds indicated that sallying insectivores (F6 = 22.95, P < 0.001), arboreal foliage-gleaning frugivores (F6 = 3.87, P < 0.001) and arboreal foliage-gleaning insectivore/frugivores (F6 = 4.42, P < 0.001) showed a significant difference in habitat selection at different distances from the edge to the interior of the forest. This finding shows that changes in the micro-environment have a significant effect on the distribution and richness of upperstory birds. This study demonstrated that the large-sized upperstory bird species, such as barbets, broadbills and malkohas tend to forage at the forest interior and infrequently observed at the forest edge. The study also showed that the upperstory bird species were influenced by the forest edge due to factors related to microclimate. However, the response of upperstory bird species may vary from species to species and from the forest edge to the interior. The birds selected specific microhabitat and microclimate characteristics that offered optimal food, shelter and breeding sites

Pathological changes in the lungs of calves following intratracheal exposure to Pasteurella multocida B:2

Pasteurella multocida B:2 is an etiological agent of hemorrhagic septicemia in cattle and buffaloes. It is commonly fatal and considered as one of the most economically important cattle diseases in Southeast Asia. This study describes the pathological changes in the lungs of calves following intra-tracheal challenge with wild-type P. multocida B:2. For this purpose, six calves of 8-month old were selected and divided into two groups of 3 calves. Calves of Group 1 were challenged with intra-tracheal 5 ml inoculum containing 109 cfu/ml of wild-type P. multocida B:2, while the calves of Group 2 were similarly administered with PBS. All the challenged calves of Group 1 showed slight dullness and were found to be inactive within 72 hours after inoculation, but none died. Meanwhile, their lungs showed petechiations and patches of acute pneumonia affecting few lobules. Histological examinations revealed the presence of haemorrhages into the alveoli, whereas some sections showed thickened inter-alveolar septa due to congestion and the presence of neutrophils. However, pulmonary oedema was absent. P. multocida B:2 was successfully isolated from all the calves of Group 1

Optimization of modified Bouc–Wen model for magnetorheological damper using modified cuckoo search algorithm

This article presents a new modified cuckoo search algorithm with dynamic discovery probability and step-size factor for optimizing the Bouc–Wen Model in magnetorheological damper application. The newly proposed algorithm was tested using a set of standard benchmark functions with different searching space and global optima placement. An engineering optimization application was chosen to evaluate the performance of the algorithm in complex engineering applications. The optimization task involved hysteresis parameter identification of the root mean square error between the model and an actual magnetorheological damper. The magnetorheological damper response was chosen as the objective function. The final value of the fitness function and the iteration number it took to converge were used as the qualifying indicator to the proposed cuckoo search algorithm efficiency. A comparison was done against particle swarm optimization, genetic algorithm, and sine–cosine algorithm, where the modified cuckoo search algorithm showed the lowest root mean square error and fastest convergence rate among the three algorithms

Fauna Diversity in Tropical Rainforest: Threats from Land-Use Change

Tropical rainforests are the cradle of life (perfect conditions for life) on Earth, i.e., rich in plant species composition (>250 plant species/hectare) and fauna diversity (>50% of animal species in the world). Rainforests occur near the Earth\u27s equator and cover 6% of the Earth\u27s surface across the tropical regions and are characterized by wet climate, i.e., heavy rainfall (125—660 cm), relative humidity (77—88%) and temperature (20—34°C). They are dominated by a wide range of broad-leaved trees that form dense canopy and the most complex ecosystem. Currently, the tropical rainforest ecosystem is changing faster than ever in human history due to anthropogenic activities, such as habitat loss and degradation due to deforestation for timber and conversion into agriculture fields (oil palm plantation), mining, fire, climate change, etc. The habitat loss and degradation had adversely influenced the distribution and richness of the fauna species. The current information on the fauna diversity of tropical rainforest is not sufficient and in the future, more research is required to document the various community parameters of the fauna species in order to conserve and protect them. For better future, conservation, and management, we must identify the major drivers of changes and how these factors alter the tropical rainforest

Analysis Of Potential Solutions To Audible Tire Cavity And Rim Coupling Resonance Noise

The coupling of the tire cavity and tire rim resonance imparts a force upon the wheel spindle which is transmitted to the vehicle interior to produce undesirable noise levels. Modifications to the tire rim or tire cavity can decouple these resonances by shifting the natural frequency outside of the 200 –250 Hz range to reduce the audible noise levels. Through experiment and analysis several potential solutions have been compared for their commercial viability. Modifications of the rim included the Kühl wheel design and the implementation of a Helmholtz resonator, whilst tire cavity modifications included the extrusion of rubber from the tire into the cavity, the introduction of asound absorption material and an elastic ring with eparator fins which extends into the cavity due to centrifugal forces. Through QFD analysis the elastic ring design was found to be most commercially viable in terms of performance, cost, safety,versatility, durability and manufacturing readiness