Raheema Tahir | University of Karachi (original) (raw)
Books by Raheema Tahir
Wetlands have played a critical role in the development of human society. For thousands of years ... more Wetlands have played a critical role in the development of human society. For thousands of years rural communities have relied upon their fertile soils to grow crops, grazed livestock on their rich pastures, fished their productive waters, and harvested a diversity of products ranging from timber to wild game. In this way the major river systems of the world, the Niger, Nile, Tigris-Euphrates, Ganges, and Mekong among them, have supported the development of rich and sophisticated civilizations that exploited the productive wetland ecosystems of their valleys.
Being an interdisciplinary activity, computer modelling of bird flight tends to fall into the cha... more Being an interdisciplinary activity, computer modelling of bird flight tends to fall into the chasm between ornithology and engineering. Ornithologists mistrust calculation, while engineers think birdwatching is frivolous. It may seem obvious that aeronautical theory can be adapted to cover bird flight, but when I first attempted to do that, it was seen in ornithological circles as an eccentric activity, with little or no practical use. My earlier book Bird Flight Performance was politely received but biologists were unconvinced that they needed it. The present book, which is backed by a far more capable computer programme, is a fresh attempt to show why a physical theory is necessary as a framework for any quantitative discussion of animal flight. The barrier to communication between ornithologists and aeronautical engineers is due to their different attitudes to numbers. Biologists readily accept that the rate at which a bird needs energy to support its weight in air might be correlated with the wing span, but balk at the idea that this measurement (the distance between the wing tips) actually determines the power requirement, and can be used to calculate it for any bird, without the need to measure power or run regressions. There is actually no way to use statistical methods to predict the power requirements of even one species, because several variables are involved. These include the wing span, the forward speed, the strength of gravity, and the density of the air, and each of them affects the power in different ways. All of this, and much more, is represented in classical aeronautical theory, of which the relevant parts have been exhaustively tested over the last hundred years, and I have built the Flight programme on this foundation. Ornithologists sometimes want to use the traditional ''wing length'' as a substitute for the wing span, but this will not do. The power estimates are not correlations, but absolute numbers, calculated from Newtonian mechanics, and the right input numbers have to be used. The requirement to be aware of the definition of each variable and its physical dimensions is obvious to engineers, but less so to those who have been accustomed to relying exclusively on statistical methods. A statistical package looks for patterns in sets of numbers, and will usually produce a result whatever the numbers mean, or even if they mean nothing at all. The difficulty that many biologists seem to have with ix
cientific Publications of the Cleveland Museum of Natural History, 1931
FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS, 1985
This field guide includes the marine and brackish-water species of bony fishes, sharks, batoid fi... more This field guide includes the marine and brackish-water
species of bony fishes, sharks, batoid fishes, lobsters,
shrimps, crabs and cephalopods believed to be of interest
to fisheries in Pakistan. Each major resources group is
introduced by a general section on technical terms, followed by an annotated and illustrated list of the more
important species which includes FAO names, local names
commonly used (Sindhi, Baluchi and English), maximum
size, habitat, fishing gear and interest to fisheries. A
composite index of scientific and vernacular family and
species names is also provided.
Papers by Raheema Tahir
Wetlands have played a critical role in the development of human society. For thousands of years ... more Wetlands have played a critical role in the development of human society. For thousands of years rural communities have relied upon their fertile soils to grow crops, grazed livestock on their rich pastures, fished their productive waters, and harvested a diversity of products ranging from timber to wild game. In this way the major river systems of the world, the Niger, Nile, Tigris-Euphrates, Ganges, and Mekong among them, have supported the development of rich and sophisticated civilizations that exploited the productive wetland ecosystems of their valleys.
Being an interdisciplinary activity, computer modelling of bird flight tends to fall into the cha... more Being an interdisciplinary activity, computer modelling of bird flight tends to fall into the chasm between ornithology and engineering. Ornithologists mistrust calculation, while engineers think birdwatching is frivolous. It may seem obvious that aeronautical theory can be adapted to cover bird flight, but when I first attempted to do that, it was seen in ornithological circles as an eccentric activity, with little or no practical use. My earlier book Bird Flight Performance was politely received but biologists were unconvinced that they needed it. The present book, which is backed by a far more capable computer programme, is a fresh attempt to show why a physical theory is necessary as a framework for any quantitative discussion of animal flight. The barrier to communication between ornithologists and aeronautical engineers is due to their different attitudes to numbers. Biologists readily accept that the rate at which a bird needs energy to support its weight in air might be correlated with the wing span, but balk at the idea that this measurement (the distance between the wing tips) actually determines the power requirement, and can be used to calculate it for any bird, without the need to measure power or run regressions. There is actually no way to use statistical methods to predict the power requirements of even one species, because several variables are involved. These include the wing span, the forward speed, the strength of gravity, and the density of the air, and each of them affects the power in different ways. All of this, and much more, is represented in classical aeronautical theory, of which the relevant parts have been exhaustively tested over the last hundred years, and I have built the Flight programme on this foundation. Ornithologists sometimes want to use the traditional ''wing length'' as a substitute for the wing span, but this will not do. The power estimates are not correlations, but absolute numbers, calculated from Newtonian mechanics, and the right input numbers have to be used. The requirement to be aware of the definition of each variable and its physical dimensions is obvious to engineers, but less so to those who have been accustomed to relying exclusively on statistical methods. A statistical package looks for patterns in sets of numbers, and will usually produce a result whatever the numbers mean, or even if they mean nothing at all. The difficulty that many biologists seem to have with ix
cientific Publications of the Cleveland Museum of Natural History, 1931
FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS, 1985
This field guide includes the marine and brackish-water species of bony fishes, sharks, batoid fi... more This field guide includes the marine and brackish-water
species of bony fishes, sharks, batoid fishes, lobsters,
shrimps, crabs and cephalopods believed to be of interest
to fisheries in Pakistan. Each major resources group is
introduced by a general section on technical terms, followed by an annotated and illustrated list of the more
important species which includes FAO names, local names
commonly used (Sindhi, Baluchi and English), maximum
size, habitat, fishing gear and interest to fisheries. A
composite index of scientific and vernacular family and
species names is also provided.