Procedural Generation and Rendering of Large-Scale Open-World Environments

Open-world video games give players a large environment to explore along with increased freedom to navigate and manipulate that environment. These requirements pose several problems that must be addressed by a game\u27s graphics engine. Often there are a large number of visible objects, such as all of the trees in a forest, as well as objects comprised of large amounts of geometry, such as terrain. An open-world graphics engine must be able to render large environments at varying levels of detail and smoothly transition between detail levels to provide a believable experience. Often this involves finding a way to both store and generate the large amounts of geometry that represent the environment. In this thesis we present a system for generating and rendering large exterior environments, with a focus on terrain and vegetation. We use a region-based procedural generation algorithm to create environments of varying types. This algorithm produces content that can be rendered at multiple levels of detail. The terrain is rendered volumetrically to support caves, overhangs, and cliffs, but is also rendered using heightmaps to allow for large view distances. Vegetation is implemented using procedurally generated meshes and impostors. The volumetric terrain is editable in real time, which limits our ability to pre-generate or cache large amounts of geometry, and also limits the number of assumptions we can make with regard to visibility. We support a view distance of at least 25 miles in each direction, though distant objects are rendered at low resolution. The heightmap terrain used to achieve this view distance consists of over 360,000 triangles. Our system runs at 180 frames per second on commodity desktop hardware

On the Pathology of Hodgkin's Disease

In Part I an attempt was made to offer a brief and reasonably critical account of the inherent peculiarities of the structure and of the diseases of the reticulo---endothelial system. Particular emphasis was accorded to works which have served to integrate the concept of lymphoid tissue sarcoma. While it is doubtful whether knowledge is yet adequate enough to endorse this idea universally, it has the advantage of being a practical generalisation which simplifies the subject. The view that the morbid process, primary reticulosis, was covered by the generic lymphoid tissue sarcoma was also supported. In Part II some account was given of the lymphatics and lymphoid tissue. In this outline attention was drawn to the mysterious and bewildering problems inseparable from the system. The structure of lymph nodes was given with observations on their development, involution, and possible neogenesis in adult life. From these studies it emerged that the full complement of lymph nodes in the locus examined was probably attained in adolescence or early adult life, and that fat replacement was the usual mode of atrophy. Attention was also drawn to the rarity of fibrosis in physiological nodes, except where it was the result of blood vascular hyaline change. In Part III Hodgkin's disease was studied. In the introduction of this part of the work the historical aspect of the malady was recorded, with, it is hoped, advertisement of interesting and possibly less well-known facts about it. This was followed by a critical consideration on the nature of the disease and its morbid anatomy, the latter being /illustrated illustrated in part by analyses of the cases coming to necropsy at Glasgow Royal Infirmary over a period of fifty years. In this part also were the findings of a large series of biopsy specimens. Here endeavours were made to shew the microscopical variations in morphology in the lesion, and to demonstrate the affinities of other lymphoid tissue sarcomata with the disease. Within the resources available the generic lymphoid tissue sarcoma was established, and links between the better recognised variants were presented with a reasonable degree of conviction. In the necropsy series a detailed study of thirteen cases of Hodgkin's disease or reticulum cell sarcoma was offered. In these it was shewn that the favourite locus was lymphoid tissue, that complete systematisation was rare, and that metamorphosis to a more tumour-like lesion was common. In Part IV two components of the Hodgkin's disease complex were studied in relation to general pathology. The view that fibrosis, an essential and inherent peculiarity of the Hodgkin's disease lesion, was represented in certain other morbid states was submitted. This was illustrated by brief accounts of some diseases where quasi-neoplastic features are shewn by connective tissue. Eosinophilia in tumours was also made the subject of investigation and revealed that the phenomenon, while possibly not so rare as might be expected, was not nearly so common as in Hodgkin's disease. Some evidence was found for the cyto-metaplastic origin of eosinophiles in Hodgkin's disease, but possibly due to the restriction to histological as opposed to cytological methods, the results were not highly conclusive. In Part V an experimental attempt to reproduce the disease by /chronic chronic trypan blue poisoning of rats and mice proved unsuccessful, although interesting results followed. The main contention in this thesis has been that Hodgkin's disease is a neoplasm. Perhaps the following may influence the reader more convincingly than I have been able to do by so much work. The reasons for human beliefs depend chiefly upon Authority, Intuition, and Scientific Method. The last two have been exploited as far as I have been able; the foremost remains. As a junior student I saw a case of Hodgkin's disease first in the wards of the Late Professor Archibald Harrington, at Glasgow Royal Infirmary. I was chagrined at the doubt cast on its nature in the discussion which followed the demonstration; at twenty, one is very intolerant of obscure aetiology! On my return home I imprudently assailed my Father with the question at the dinner table, where even renal oedema was taboo. He was exceedingly angry. There was a dreadful silence, and then he relented - 'of course it is tumour, - but mind to whom you say that' Nothing more was said. I submit that this terse pronouncement has been my most precious axiom, with deepest respect and affection

Higher aggression towards closer relatives by soldier larvae in a polyembryonic wasp

In the polyembryonic wasp Copidosoma floridanum, females commonly lay one male and one female egg in a lepidopteran host. Both sexes proliferate clonally within the growing host larva. Distinct larval castes develop from each wasp egg, the majority being ‘reproductives’ plus some ‘soldiers’ which sacrifice reproduction and attack competitors. Maturing mixed sex broods are usually female biased, as expected when intra-brood mating is common. Pre-mating dispersal followed by outbreeding is expected to increase sexual conflict over brood sex ratios and result in greater soldier attack rates. Owing to sexually asymmetric relatedness, intra-brood conflicts are expected to be resolved primarily via female soldier attack. We observed soldier behaviour in vitro to test whether lower intra-brood relatedness (siblings from either within-strain or between-strain crosses were presented) increased inter-sexual aggression by female as well as male soldiers. As found in prior studies, females were more aggressive than males but, contrary to expectations and previous empirical observations, soldiers of both sexes showed more aggression towards more closely related embryos. We speculate that lower intra-brood relatedness indicates maternal outbreeding and may suggest a rarity of mating opportunities for reproductives maturing from the current brood, which may enhance the value of opposite sex brood-mates, or that higher aggression towards relatives may be a side-effect of mechanisms to discriminate heterospecific competitors

Identification of a non-mammalian leptin-like gene:characterization and expression in the tiger salamander (Ambystoma tigrinum)

Leptin is well established as a multifunctional cytokine in mammals. However, little is known about the evolution of the leptin gene in other vertebrates. A recently published set of ESTs from the tiger salamander (Ambystoma tigrinum) contains a sequence sharing 56% nucleotide sequence identity with the human leptin cDNA. To confirm that the EST is naturally expressed in the salamander, a 409 bp cDNA was amplified by RT-PCR of salamander testis and stomach mRNAs. The coding sequence of the cDNA is predicted to encode 169 amino acids, and the mature peptide to consist of 146 residues, as in mammals. Although the overall amino acid identity with mammalian leptins is only 29%, the salamander and mammalian peptides share common structural features. An intron was identified between coding exons providing evidence that the sequence is present in the salamander genome. Phylogenetic analysis showed a rate of molecular divergence consistent with the accepted view of vertebrate evolution. The pattern of tissue expression of the leptin-like cDNA differed between metamorphosed adult individuals of different sizes suggesting possible developmental regulation. Expression was most prominent in the skin and testis, but was also detected in tissues in which leptin mRNA is present in mammals, including the fat body, stomach, and muscle. The characterization of a salamander leptin-like gene provides a basis for understanding how the structure and functions of leptin have altered during the evolution of tetrapod vertebrates

Vibronic interactions in the visible and near-infrared spectra of C60− anions

Electron-phonon coupling is an important factor in understanding many properties of the C60 fullerides. However, there has been little success in quantifying the strength of the vibronic coupling in C60 ions, with considerable disagreement between experimental and theoretical results. We will show that neglect of quadratic coupling in previous models for C60- ions results in a significant overestimate of the linear coupling constants. Including quadratic coupling allows a coherent interpretation to be made of earlier experimental and theoretical results which at first sight are incompatible