158 research outputs found
Advanced-Canopy-Atmosphere-Soil Algorithm (ACASA model) for estimating mass and energy fluxes
No full textThere is a recognized need to improve land surface models that simulate mass and energy fluxes
between terrestrial ecosystems and atmosphere. In particular, long-term land planning strategies at local
and regional scales require better understanding of agricultural ecosystem capacity to exchange CO2and water. One of the more elaborate models for flux modelling is the Advanced Canopy-Atmosphere-Soil
Algorithm (ACASA) model (Pyles et al., 2000), which provides micro-scale and regional-scale
fluxes. The ACASA model allows for characterization of energy and carbon fluxes. It is a higher-order
closure model used to estimate fluxes and profiles of heat, water vapor, carbon and momentum within
and above canopy using third-order closure equations. It also estimates turbulent profiles of velocity,
temperature, humidity within and above canopy. The ACASA model estimates CO2fluxes using a
combination of Ball-Berry and Farquhar equations. In addition, the effects of water stress on stomata,
transpiration and CO2assimilation are considered. The model was mainly used over dense canopies
(Pyles et al. 2000, 2003) in the past, so the aim of this work was to test the ACASA model over a
sparse canopy for estimating mass and energy fluxes, comparing model output with field measurements
taken over a vineyard located in Montalcino, Tuscany, Italy
β-diversity of deep-sea holothurians and asteroids along a bathymetric gradient (NE Atlantic)
No full textMeasuring and understanding patterns of ?-diversity remain major challenges in community ecology. Recently, ?-diversity has been shown to consist of 2 distinct components: (1) spatial turnover and (2) species loss leading to nestedness. Both components structure deep-sea macrofaunal assemblages but vary in importance among taxa and ocean basins and with energy availability. Here, we present the first evidence for turnover and nestedness along a bathymetric gradient in 2 major megafaunal taxa, holothurians and asteroids. Turnover is the dominant component of ?-diversity throughout bathyal and abyssal zones in both taxa, despite major differences in ?-diversity and trophic composition. High spatial turnover suggests a role for evolutionary adaptation to environmental circumstances within depth bands. This pattern differs fundamentally from those in some macrofaunal groups in low-energy environments where abyssal nestedness is high and diversity low, with diversity maintained partly by source-sink dynamics
Il Modello ACASA per la stima degli scambi di carbonio negli ecosistemi mediterranei
No full textL’attività di ricerca finalizzata allo sviluppo e alla validazione di modellistica avanzata per
la contabilizzazione del bilancio del carbonio nei sistemi agrari e forestali nasce da una intensa
collaborazione con l’Università della California. In particolare è in fase di studio il modello
ACASA (Advanced Canopy-Atmosphere-Soil Algorithm), che è attualmente uno dei modelli del
tipo soil-vegetation-atmosphere transfer (SVAT) più sofisticati. ACASA contiene equazioni
differenziali di terzo ordine per simulare i flussi di energia e materia nella canopy (10 strati
atmosferici all’interno e 10 al di sopra), mentre il suolo è suddiviso in 15 strati. Una combinazione
delle equazioni di Ball-Berry e Farquhar è utilizzata per stimare il flusso di CO2. Il modello
considera gli effetti dello stress idrico sulla traspirazione e sull’assimilazione della vegetazione
Tyrannosaurus rex Osborn 1905
No full textWhether Tyrannosaurus rex was likely to have found food primarily by predation or scavenging has been debated for close to a century without resolution (Erickson et al. 1996; Erickson 1999). Much of this debate has used arguments based on jaw morphology and dentition. Here, we use calculations of energy gains and losses to estimate the minimum carrion productivity an ecosystem must provide in order to support an obligate scavenger of the 6 tonne (6000 kg) mass of T. rex. Our estimates suggest that carrion productivity equivalent to the current Serengeti would have been sufficient to support such a scavenger. Hence, we argue on the basis of physiological ecology that T. rex need not have been an active predator and could have found sufficient food to support itself purely by scavenging. Our hypothesis is that the key constraint for scavengers is generally their ability to find food items. This is in contrast to predators, where capturing rather than discovering prey is the key constraint, and herbivores, where processing consumed food is often the key restriction on energy gain rate. We assume that the scavenger spends a constant fraction (a) of its time searching for food items that are distributed with a constant uniform density (f). If, when active, the scavenger searches out area at a rate V, then it finds food items at a rate a fV. We assume that it extracts an amount of energy E from each food item found. Hence, the rate of energy gathering (E in) is a f VE. We assume that the individual has a resting metabolic rate R, but that searching for food requires extra energy investment at rate S. Thus, the rate of energy expenditure (E o ut) is given by R + a S, and scavengers attempt to optimize net energy gain (E net) given by E n et = E in ‾ E o ut = a(f VE ‾ S) ‾ R. (2.1) If we demand that E net be positive then we can rearrange equation (2.1) as a restriction on the energy density of food available for scavenging: for a positive energy budget we demand that the density of food energy available to a scavenger is greater than a critical value given by a S + R f E m in =. a V (2.2) The right-hand side of this is the minimum energy density that an ecosystem needs to have to support a scavenger. We will now estimate this for a scavenging T. rex and compare this with the energy density of carrion in the extant Serengeti. We will assume that restrictions owing to nightfall, bad weather and sleep mean that on average the scavenger can actively seek food for 50% of the 24 hour day, so we set a = 0.5. The relationship between the mass M of a reptile in kilograms and the resting metabolic rate R in watts has been described by Schmidt-Nielson (1984) R = 0.38 M 0.83. (2.3) There have been various estimates of the live mass of a full-sized T. rex, ranging from 3000 to 8000 kg (Farlow et al. 1995; Christiansen 1997; Seebacher 2001). Recent papers seem to be converging towards estimates close to 6 tonnes, so we will use a value of 6000 kg throughout this paper. Substituting this into equation (2.3) gives a value for R of 520 W. The relationship between the mass M of an ectotherm (in kg), the speed of travel v (in m s ‾1) and the extra cost of travel S (in W) has been suggested by Bennett (1982) to be S = 10.3 vM 0.64. (2.4) Reptiles can sustain a speed equivalent to 10% of their maximum speed (Bennett & Ruben 1979). The maximum speed of equivalent-sized mammals and reptiles is similar (Bennett & Ruben 1979). The following relationship between mass M (in kg) and maximum speed v m ax (in m s ‾1) has been proposed by Alexander (1977): v m ax = 8.5 M ‾ 0.08. (2.5) Substituting M = 6000 in equation (2.5) gives a maximum speed for a T. rex of 4.2 m s ‾ 1. This compares well with a recent estimate of 5 m s ‾1 based on T. rex ’s limb mor- * Author for correspondence ([email protected]). phology (Hutchinson & Garcia 2002). We will assume that sustained travelling speed, v, is 10% of our estimate, i.e. 0.42 m s ‾ 1. If we substitute for v and M in equation (2.4), then this gives an added cost of travel S of 1100 W. The rate at which an area is swept, V, is simply the sustained travel speed v multiplied by twice the distance at which food can be detected, which we will denote d. That is V = 0.84 d. (2.6) Substituting the parameter values derived in equation (2.6) into equation (2.2) gives an equation for the minimum energy density of carrion (in J m ‾2) that could sustain an animal (fE m in) in terms of the distance at which it could detect carrion (d) as follows: 2550 f E m in =. d (2.7) This relationship is plotted for a range of d values from 10 m to 10 km in figure 1. To give us something to compare this against, we can estimate the energy density of carrion available each day from ungulate herbivores in the modern Serengeti ecosystem. It has been estimated that a total weight of 4´ 107 kg of ungulates die in the Serengeti each year (Houston 1979). Assuming that these have an mass-specific energy content of 7´ 106 J kg ‾1 (Peters 1983), and that the Serengeti stretches over 25 000 km 2 (Sinclair & Norton-Griffiths 1979). This gives a mean energy density of 31 J m ‾ 2 d ‾1. When we compare this value with figure 1, we see that even if we make the conservative assumption that animals that die only remain available to T. rex for 24 hours (before spoiling or being consumed by other scavengers), then, if it is able to monopolize all the food it finds and can detect food at a range of 80 m, an ecosystem of similar productivity to the current Serengeti would provide sufficient food for such a scavenger. One reason for caution in the interpretation of our results is that the allometric relations used are based on data from extant reptiles, and consequently very few of the species used to generate the relations would have a mass approaching even 1% of our estimated mass for T. rex. Of our estimates, the sustainable travel speed of 0.42 m s ‾ 1 seems rather low for a bipedal animal with 2.5 m legs (see Fitzgerald (2002) and references therein). If we repeat our calculations assuming a sustainable running speed of 2.1 m s ‾ 1, then this changes equation (2.7) to 1600 f E m in =. d (2.8) The faster running speed increases the area that can be swept for food faster than it increases the total energetic requirements of that animal, and so this leads to a reduction in the food density required to sustain the scavenger. Thus, our initial assumption of a low running speed can be seen as conservative, making a scavenging lifestyle challenging to maintain. Some scientists consider that mammals (rather than reptiles) are a more appropriate model for dinosaurs (e.g. Bakker 2001). It is possible to repeat our calculations under such an assumption. Schmidt-Nielson (1984) suggests that this would change our equation for R to R = 0.38 M 0.83, (2.9) increasing R substantially to 2300 W for our 6000 kg animal. Calder (1996) suggests that, for a mammal, the equation for S becomes S = 10.7 vM 0.68. (2.10) Bennett & Ruben (1979) suggest that the sustainable speed of mammals is 50% of their maximum speed, hence we will assume that v is 2.1 m s ‾1. If we finally assume that a is unchanged at 0.5, then (using mammals rather than reptiles as a model) changes equation (2.7) to 3100 f E m in =. d (2.11) Hence, we see that substantial compensation for higher resting and movement costs in a mammal-like T. rex may come from a mammalian physiology allowing a higher sustainable rate of movement. The consequence of this is that the minimum food density required by our scavenger is only slightly increased if a mammalian model rather than a reptilian model is assumed. 3. CONCLUSIONS Our calculation suggests that T. rex would be able to gather enough food to survive as a pure scavenger if a number of conditions are met. One is that the ecosystem yields the same density of carrion as the current Serengeti. Estimates of primary productivity at the place and time appropriate to T. rex vary widely but encompass values similar to that of the present-day Serengeti (Beerling & Woodward 2001). Any given primary productivity would have supported a greater biomass of ectothermic dinosaurs compared to the endothermic mammals that dominate the extant Serengeti (Farlow 1990). This higher biomass will more than compensate for the lower turnover rate per unit biomass that one would predict if dinosaurian herbivores had longer lifespans than the mammalian herbivores of the extant Serengeti, on account both of their larger size and probably lower specific metabolic rates. Another condition is that T. rex can detect carcasses at a distance of 80 m. Given the performance of polar bears in detecting seals over distances of kilometres (Stirling 1977) and the ability of turkey vultures to find 80% of experimentally provided chicken carcasses in tropical rainforest within 12 hours of presentation (Houston 1986), this seems likely to have been comfortably within T. rex ’s compass. Brochu (2000) argues, on the basis of computed tomographic analysis of a fossil skull, that T. rex had greatly enlarged olfactory bulbs, suggestive of high olfactory acuity. Farlow (1994) suggests that the upright stance of T. rex could have aided carrion location, both by visual and olfactory pathways. We also assumed that the fallen carcass was only detectable to T. rex for a period of 24 hours. Little is known about how long a carcass is accessible to vertebrate scavenges. Small (chicken) carcasses in tropical African forests were totally consumed by maggots within 3 days (Houston 1987). Hence, our assumption that prey is only available for 1 day seems entirely reasonable, and if anything on the low side. Our final assumption that our focal T. rex individual is able to find all the carcasses that fall in areas where it searches seems less plausible. It is likely that our T. rex would experience competition from other species and from other members of its own species. However, if we arbitrarily assume that our focal individual is only able to access 25% of the carcasses that fall, so that the ecosystem has effectively only 25% of the carrion density of the Serengeti (7.75 J m ‾2), then (from figure 1) we see that T. rex would have to be able to detect prey at a distance of 330 m to balance its energy budget. This is more challenging, but still seems within the bounds of the possible, especially if, like many extant reptiles (Zug et al. 2001), T. rex had an effective sense of smell. Hence, our conclusion is that an energy budget analysis suggests that a reptile as large as T. rex could have survived using a purely scavenging lifestyle, providing that competition for carrion was low. This conclusion leads to the obvious question, why is there not a T. rex- like scavenger on the Serengeti today? Or generally, we must ask why vultures are the only extant vertebrates that have a predominantly scavenging lifestyle. The answer may be that an avian scavenger can outcompete a terrestrial one because, as mentioned in § 1, the key requirement for a scavenger is to minimize energy expenditure while searching. Compared to terrestrial locomotion, even powered flying is faster and much less energetically expensive per distance covered (Schmidt- Nielson 1984), and birds like vultures that make extensive use of soaring have dramatically lower energy expenditure than any terrestrial scavenger could have. If T. rex was a scavenger, then this was probably only possible because avian radiation had yet to have a substantial effect on ecosystems. It may well be, as suggested by Farlow (1994), that T. rex was an opportunist flesh eater, combining scavenging carrion with active predation. That said, our calculations suggest that total (or near total) dependence on carrion (in the manner of extant vultures) may at least have been feasible. a S + R f E m in =. a V (2.2) The right-hand side of this is the minimum energy density that an ecosystem needs to have to support a scavenger. We will now estimate this for a scavenging T. rex and compare this with the energy density of carrion in the extant Serengeti. We will assume that restrictions owing to nightfall, bad weather and sleep mean that on average the scavenger can actively seek food for 50% of the 24 hour day, so we set a = 0.5. The relationship between the mass M of a reptile in kilograms and the resting metabolic rate R in watts has been described by Schmidt-Nielson (1984) R = 0.38 M 0.83. (2.3) There have been various estimates of the live mass of a full-sized T. rex, ranging from 3000 to 8000 kg (Farlow et al. 1995; Christiansen 1997; Seebacher 2001). Recent papers seem to be converging towards estimates close to 6 tonnes, so we will use a value of 6000 kg throughout this paper. Substituting this into equation (2.3) gives a value for R of 520 W. The relationship between the mass M of an ectotherm (in kg), the speed of travel v (in m s ‾1) and the extra cost of travel S (in W) has been suggested by Bennett (1982) to be S = 10.3 vM 0.64. (2.4) Reptiles can sustain a speed equivalent to 10% of their maximum speed (Bennett & Ruben 1979). The maximum speed of equivalent-sized mammals and reptiles is similar (Bennett & Ruben 1979). The following relationship between mass M (in kg) and maximum speed v m ax (in m s ‾1) has been proposed by Alexander (1977): v m ax = 8.5 M ‾ 0.08. (2.5) Substituting M = 6000 in equation (2.5) gives a maximum speed for a T. rex of 4.2 m s ‾ 1. This compares well with a recent estimate of 5 m s ‾1 based on T. rex ’s limb mor- * Author for correspondence ([email protected]). phology (Hutchinson & Garcia 2002). We will assume that sustained travelling speed, v, is 10% of our estimate, i.e. 0.42 m s ‾ 1. If we substitute for v and M in equation (2.4), then this gives an added cost of travel S of 1100 W. The rate at which an area is swept, V, is simply the sustained travel speed v multiplied by twice the distance at which food can be detected, which we will denote d. That is V = 0.84 d. (2.6) Substituting the parameter values derived in equation (2.6) into equation (2.2) gives an equation for the minimum energy density of carrion (in J m ‾2) that could sustain an animal (fE m in) in terms of the distance at which it could detect carrion (d) as follows: 2550 f E m in =. d (2.7) This relationship is plotted for a range of d values from 10 m to 10 km in figure 1. To give us something to compare this against, we can estimate the energy density of carrion available each day from ungulate herbivores in the modern Serengeti ecosystem. It has been estimated that a total weight of 4´ 107 kg of ungulates die in the Serengeti each year (Houston 1979). Assuming that these have an mass-specific energy content of 7´ 106 J kg ‾1 (Peters 1983), and that the Serengeti stretches over 25 000 km 2 (Sinclair & Norton-Griffiths 1979). This gives a mean energy density of 31 J m ‾ 2 d ‾1. When we compare this value with figure 1, we see that even if we make the conservative assumption that animals that die only remain available to T. rex for 24 hours (before spoiling or being consumed by other scavengers), then, if it is able to monopolize all the food it finds and can detect food at a range of 80 m, an ecosystem of similar productivity to the current Serengeti would provide sufficient food for such a scavenger. One reason for caution in the interpretation of our results is that the allometric relations used are based on data from extant reptiles, and consequently very few of the species used to generate the relations would have a mass approaching even 1% of our estimated mass for T. rex. Of our estimates, the sustainable travel speed of 0.42 m s ‾ 1 seems rather low for a bipedal animal with 2.5 m legs (see Fitzgerald (2002) and references therein). If we repeat our calculations assuming a sustainable running speed of 2.1 m s ‾ 1, then this changes equation (2.7) to 1600 f E m in =. d (2.8) The faster running speed increases the area that can be swept for food faster than it increases the total energetic requirements of that animal, and so this leads to a reduction in the food density required to sustain the scavenger. Thus, our initial assumption of a low running speed can be seen as conservative, making a scavenging lifestyle challenging to maintain. Some scientists consider that mammals (rather than reptiles) are a more appropriate model for dinosaurs (e.g. Bakker 2001). It is possible to repeat our calculations under such an assumption. Schmidt-Nielson (1984) suggests that this would change our equation for R to R = 0.38 M 0.83, (2.9) increasing R substantially to 2300 W for our 6000 kg animal. Calder (1996) suggests that, for a mammal, the equation for S becomes S = 10.7 vM 0.68. (2.10) Bennett & Ruben (1979) suggest that the sustainable speed of mammals is 50% of their maximum speed, hence we will assume that v is 2.1 m s ‾1. If we finally assume that a is unchanged at 0.5, then (using mammals rather than reptiles as a model) changes equation (2.7) to 3100 f E m in =. d (2.11) Hence, we see that substantial compensation for higher resting and movement costs in a mammal-like T. rex may come from a mammalian physiology allowing a higher sustainable rate of movement. The consequence of this is that the minimum food density required by our scavenger is only slightly increased if a mammalian model rather than a reptilian model is assumed. 3. CONCLUSIONS Our calculation suggests that T. rex would be able to gather enough food to survive as a pure scavenger if a number of conditions are met. One is that the ecosystem yields the same density of carrion as the current Serengeti. Estimates of primary productivity at the place and time appropriate to T. rex vary widely but encompass values similar to that of the present-day Serengeti (Beerling & Woodward 2001). Any given primary productivity would have supported a greater biomass of ectothermic dinosaurs compared to the endothermic mammals that dominate the extant Serengeti (Farlow 1990). This higher biomass will more than compensate for the lower turnover rate per unit biomass that one would predict if dinosaurian herbivores had longer lifespans than the mammalian herbivores of the extant Serengeti, on account both of their larger size and probably lower specific metabolic rates. Another condition is that T. rex can detect carcasses at a distance of 80 m. Given the performance of polar bears in detecting seals over distances of kilometres (Stirling 1977) and the ability of turkey vultures to find 80% of experimentally provided chicken carcasses in tropical rainforest within 12 hours of presentation (Houston 1986), this seems likely to have been comfortably within T. rex ’s compass. Brochu (2000) argues, on the basis of computed tomographic analysis of a fossil skull, that T. rex had greatly enlarged olfactory bulbs, suggestive of high olfactory acuity. Farlow (1994) suggests that the upright stance of T. rex could have aided carrion location, both by visual and olfactory pathways. We also assumed that the fallen carcass was only detectable to T. rex for a period of 24 hours. Little is known about how long a carcass is accessible to vertebrate scavenges. Small (chicken) carcasses in tropical African forests were totally consumed by maggots within 3 days (Houston 1987). Hence, our assumption that prey is only available for 1 day seems entirely reasonable, and if anything on the low side. Our final assumption that our focal T. rex individual is able to find all the carcasses that fall in areas where it searches seems less plausible. It is likely that our T. rex would experience competition from other species and from other members of its own species. However, if we arbitrarily assume that our focal individual is only able to access 25% of the carcasses that fall, so that the ecosystem has effectively only 25% of the carrion density of the Serengeti (7.75 J m ‾2), then (from figure 1) we see that T. rex would have to be able to detect prey at a distance of 330 m to balance its energy budget. This is more challenging, but still seems within the bounds of the possible, especially if, like many extant reptiles (Zug et al. 2001), T. rex had an effective sense of smell. Hence, our conclusion is that an energy budget analysis suggests that a reptile as large as T. rex could have survived using a purely scavenging lifestyle, providing that competition for carrion was low. This conclusion leads to the obvious question, why is there not a T. rex- like scavenger on the Serengeti today? Or generally, we must ask why vultures are the only extant vertebrates that have a predominantly scavenging lifestyle. The answer may be that an avian scavenger can outcompete a terrestrial one because, as mentioned in § 1, the key requirement for a scavenger is to minimize energy expenditure while searching. Compared to terrestrial locomotion, even powered flying is faster and much less energetically expensive per distance covered (Schmidt- Nielson 1984), and birds like vultures that make extensive use of soaring have dramatically lower energy expenditure than any terrestrial scavenger could have. If T. rex was a scavenger, then this was probably only possible because avian radiation had yet to have a substantial effect on ecosystems. It may well be, as suggested by Farlow (1994), that T. rex was an opportunist flesh eater, combining scavenging carrion with active predation. That said, our calculations suggest that total (or near total) dependence on carrion (in the manner of extant vultures) may at least have been feasible.Published as part of Ruxton, Graeme D. & Hou
Post-war British working-class fiction with special reference to the novels of John Braine, Alan Sillitoe, Stan Barstow, David Storey and Barry Hines
No full textThis study is about British working-class fiction in the post-war period.
It covers various authors such as Robert Tressell, George Orwell, Walter Greenwood, Lewis Grassic Gibbon and DH Lawrence from the early twentieth century; writers traditionally classified as 'Angry Young Men' like John Osborne, Arnold Wesker, Shelagh Delaney, John Wain and
Kingsley Amis; and working-class novelists like John Braine, Stan Barstow, David Storey, Alan Sillitoe and Barry Hines from the 1950s and 1960s.
Some of the main issues dealt with in the course of this study are language, form, community, self/identity/autobiography, sexuality and relationship with bourgeois art. The major argument centres on two questions: representation of working-class life, and the
relationship between working-class literary tradition and dominant ideologies.
We will be arguing that while working-class fiction succeeded in challenging and rupturing bourgeois literary tradition, on the level of language and linguistic medium of expression for example, it utterly failed to break away from dominant, bourgeois modes of literary production in relation to form, for instance.
Our argument is situated within Marxist approaches to literature, a political and aesthetic position from which we attempt an analysis and an evaluation of this working-class literary tradition. These critical approaches provide us also with the theoretical tool to define the political perspective of this tradition, and to judge whether it was confined to a descriptive mode of representation or
located in a radical, political outlook
Towards a planning decision support system for low-carbon urban development
No full textThe flows of carbon and energy produced by urbanized areas represent one of the aspects of urban sustainability that can have an important impact on climate change. For this reason, in recent years the quantitative estimation of the so-called urban metabolism components has increasingly attracted the attention of researchers from different fields. On the other hand, it has been well recognized that the structure and design of future urban development can significantly affect the flows of material and energy exchanged by an urban area with its surroundings. In this context, the paper discusses a software framework able to estimate the carbon exchanges accounting for alternative scenarios which can influence urban development. The modelling system is based on four main components: (i) a Cellular Automata model for the simulation of the urban land-use dynamics; (ii) a transportation model, able to estimate the variation of the transportation network load and (iii) the ACASA (Advanced Canopy-Atmosphere-Soil Algorithm) model which was tightly coupled with the (iv) mesoscale weather model WRF for the estimation of the relevant urban metabolism components. An in-progress application to the city of Florence is presented and discussed
Advanced-Canopy-Atmosphere-Soil Algorithm (ACASA model) for estimating mass and energy fluxes
No full textThere is a recognized need to improve land surface models that simulate mass and energy fluxes
between terrestrial ecosystems and atmosphere. In particular, long-term land planning strategies at local
and regional scales require better understanding of agricultural ecosystem capacity to exchange CO2
and water. One of the more elaborate models for flux modelling is the Advanced Canopy-Atmosphere-Soil
Algorithm (ACASA) model (Pyles et al., 2000), which provides micro-scale and regional-scale
fluxes. The ACASA model allows for characterization of energy and carbon fluxes. It is a higher-order
closure model used to estimate fluxes and profiles of heat, water vapor, carbon and momentum within
and above canopy using third-order closure equations. It also estimates turbulent profiles of velocity,
temperature, humidity within and above canopy. The ACASA model estimates CO2 fluxes using a
combination of Ball-Berry and Farquhar equations. In addition, the effects of water stress on stomata,
transpiration and CO2 assimilation are considered. The model was mainly used over dense canopies
(Pyles et al. 2000, 2003) in the past, so the aim of this work was to test the ACASA model over a
sparse canopy for estimating mass and energy fluxes, comparing model output with field measurements
taken over a vineyard located in Montalcino, Tuscany, Italy
Art, Biography, Sexuality: Patrick Procktor and Keith Vaughan
No full textThis critical review forms a reflection on the research published within the following publications:
Patrick Procktor: Art and Life (Unicorn Press, 2010)
Keith Vaughan: The Mature Oils 1946-1977, (Sansom & Co., 2012)
The research is on two artists, Patrick Procktor (1936-2003), and Keith Vaughan (1912-1977). The monograph on Procktor – previously one of the least documented of the generation of artists who came to prominence in London in the Sixties – positions him in a history of art from which he had been notably absent. The research on Vaughan asserts a new reading of his work, one that is both deeper and more nuanced in its analysis of the ways in which personal experience and sexuality are encoded autobiographically within his work. Crucially, in both artists biography and work are symbiotically linked; the research therefore examines the links between life and art.
Revisionary in intent, the work examines trajectories of experience of gay British (or rather, English) artists in the twentieth century, artists who sought to express themselves and forge careers within the constraints of a heteronormative society, albeit one in which attitudes to sexuality were undergoing change. As gay men, both were constrained by the social mores of their times, and each used painting as a means to affirm personal and sexual identities. A key research interest is in the ways in which sexuality and persona are reflected in critical responses to the artist’s work: in Vaughan, Procktor and other gay male artists of the period. The writing on both Procktor and Vaughan examines the relationship between their personal and professional/artistic lives, framed within a broader socio-political and art historical context. It asserts the place of biography as a means to understand and form new readings of the work. The work adds substantially to the literature and wider discourse on post-war British painting and social history
Stuckey, Slave Culture - Nationalist Theory and the Foundations of Black America
No full textSlave Culture is a stimulating and well researched study into the social history of black America since the early colonial period up to the late 1930s. Professor Stuckey writes with the ease and clarity rarely found in more recent texts of black history. Slave Culture provides meaningful elaboration and examination of black society both in pre- and post-slavery America. In addition to an indepth overview of black culture and society, the author provides the reader with useful and relevant case studies of selected black Americans. The major figures included in the book are David Walker, Henry Highland Gamet, W.E.B. DuBois, and Paul Robeson
Adapting authoritarianism: institutions and co-optation in Egypt and Syria
No full textThis PhD thesis compares Egypt and Syria’s authoritarian political systems. While the tendency in social science political research treats Egypt and Syria as similarly authoritarian, this research emphasizes differences between the two systems with special reference to institutions and co-optation. Rather than reducibly understanding Egypt and Syria as sharing similar histories, institutional arrangements, or ascribing to the oft-repeated convention that “Syria is Egypt but 10 years behind,” this thesis focuses on how events and individual histories shaped each states current institutional strengthens and weaknesses. Specifically, it explains the how varying institutional politicization or de-politicization affects each state’s capabilities for co-opting elite and non-elite individuals.
Beginning with a theoretical framework that considers the limited utility of democratization and transition theoretical approaches, the work underscores the persistence and durability of authoritarianism. Chapter two details the politicized institutional divergence between Egypt and Syria that began in the 1970s. Chapter three and four examines how institutional politicization or de-politicization affects elite and non-elite individual co-optation in Egypt and Syria. Chapter five discusses the study’s general conclusions and theoretical implications.
This thesis’s argument is that Egypt and Syria co-opt elites and non-elites differently because of the varying degrees of institutional politicization in each governance system. Rather than view one country as more politically developed than the other, this work argues that Syria’s political institutions are more politicized than their Egyptian counterparts. Syria’s political arena is, thus, described as politicized-patrimonialism. Syria’s politicized-patrimonial arena produces uneven co-optation of elites and non-elites as they are diffused through competing institutions. Conversely, the Egyptian political arena remains highly personalized as weak institutions and individuals are manipulated and molded according to the president’s ruling clique. This is referred to as personalized-patrimonialism. As a consequence, Egypt’s political establishment demonstrates more flexibility in ad hoc altering and adapting its arena depending on the emergence of crises.
This study’s theoretical implications suggest that, contrary to modernization and democratization theory’s adage that institutions lead to a political development, politicized institutions within a patrimonial order actually hinder regime adaptation because consensus is harder to achieve and maintain. It is within this context that Egypt’s de-politicized institutional framework advantages its top political elite. In this reading of Egyptian and Syrian politics, Egypt’s personalized political arena is more adaptable than Syria’s. These conclusions do not indicate that political reform is a process underway in either state
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