Showing papers by "University of Florida published in 1978"
TL;DR: Adult thymectomized, irradiated and bone marrow reconstituted mice, transplanted with an irradiated thymus of A origin, generate virus-specific cytotoxic T cells specific for infected A targets but not for B targets; this result formally demonstrates the crucial role of thymic epithelial cells in the differentiation of anti-self-H-2 specificities of T cells.
Abstract: In the thymus, precursor T cells differentiate recognition structures for self that are specific for the H-2K, D, and I markers expressed by the thymic epithelium. Thus recognition of self-H-2 differentiates independently of the T cells H-2 type and independently of recognition of nonself antigen X. This is readily compatible with dual recognition by T cells but does not formally exclude a single recognition model. These conclusions derive from experiments with bone marrow and thymic chimeras. Irradiated mice reconstituted with bone marrow to form chimeras of (A X B)F1 leads to A type generate virus-specific cytotoxic T cells for infected targets A only. Therefore, the H-2 type of the host determines the H-2-restricted activity of killer T cells alone. In contrast, chimeras made by reconstituting irradiated A mice with adult spleen cells of (A X B)F1 origin generate virus-specific cytotoxic activity for infected A and B targets, suggesting that mature T cells do not change their self-specificity readily. (A X B)F1 leads to (A X C)F1 and (KAIA/DC) leads to (KAIA/DB) irradiation bone marrow chimeras responded against infected A but not B or C targets. This suggests that cytotoxicity is not generated against DC because it is abscent from the host's thymus epithelium and not against DB because it is not expressed by the reconstituting lymphoreticular system. (KBIB/DA) leads to (KCIC/DA) K, I incompatible, or completely H-2 incompatible A leads to B chimeras fail to generate any measurable virus specific cytotoxicity, indicating the necessity for I-specific helper T cells for the generation of killer T cells. Finally adult thymectomized, irradiated and bone marrow reconstituted (A X B)F1 mice, transplanted with an irradiated thymus of A origin, generate virus-specific cytotoxic T cells specific for infected A targets but not for B targets; this result formally demonstrates the crucial role of thymic epithelial cells in the differentiation of anti-self-H-2 specificities of T cells.
833 citations
TL;DR: In this paper, the Black-Scholes option pricing model was used to calculate implied variances of future stock returns and a trading strategy was developed that exploited the informational content of the implied variance.
520 citations
TL;DR: In this article, an earlier model of personal space expectations and their violations is expanded through specification of primitive terms, constitutive definitions, and the prepositional logic underlying the model.
Abstract: An earlier model of personal space expectations and their violations is expanded through specification of primitive terms, constitutive definitions, and the prepositional logic underlying the model. Five sample hypotheses are deduced and experimentally tested. Results generally support the model: violations by rewarding communicators produced more positive outcomes than violations by punishing communicators, and the relationships between distance and communication outcomes for each type of communicator were curvilinear.
434 citations
TL;DR: This work distinguishes five types of fiowers relative to hummingbird foraging, and defines six community roles for hummingbirds in exploitation of various flower types, and points out the many parallels that exist with other consumer groups.
Abstract: Amer. Zool., 18:779-795(1978). Community Organization Among Neotropical Nectar-Feeding Birds Peter Feinsinger Department of Zoology, University of Florida, Gainesville, Florida 32611 AND Robert K. Colwell Department of Zoology, University of California, Berkeley, California 94720 synopsis. Assemblages of neotropical hummingbirds are organized according to parameters of available resources and morphological-behavioral attributes of particular hummingbird species. We distinguish five types of fiowers relative to hummingbird foraging, and we define six community roles for hummingbirds in exploitation of various flower types. These roles are: high-reward trapliners, which visit but do not defend nectar-rich fiowers with long corollas; territorialists, which defend dense clumps of somewhat shorter fiowers; low- reward trapliners, which forage among a variety of dispersed or nectar-poor fiowers; territory-parasites of two types (large marauders and small filchers); and generalists, which follow shifting foraging patterns among various resources. Simple communities on islands usually contain one species of low-reward trapliner or generalist and one territorial species, and sometimes support one high-reward trapliner; often these species are sexually dimorphic. More complex mainland communities support varying numbers of species in different roles, depending on the relative importance and constancy of different flower types. High-reward trapliners are particularly important in forest under-stories, while forest canopies and open habitats support large numbers of shorter-billed, mobile birds filling the other five roles. We conclude by pointing out the many parallels that exist with other consumer groups. Our geographically diverse studies have been aided by numerous persons and organizations. In addition to those acknowledged elsewhere, we are particularly grateful to: J. A. Wolfe and L. A. Swarm, for their continuing contributions to studies on Trinidad and Tobago; S. Naeem and M. Lentrell for technical assistance; M. C. King, for expert assistance in the field and in the preparation of this paper; J. Ter- borgh, for the generous loan of unpublished data; H. A. Ford, for access to an unpublished manuscript; J. A. Brown and A. Kodric-Brown, for comments on the manuscript; A. B. Bolten, for stimulating discussions on organization among neotropical bees; and M. Bon Saint Come, for hospitality and assistance on Mar- tinique. Feinsinger's field work in summer 1975 was financed by a Venture Grant and a Faculty Research Grant from the University of Denver; his current study on Trinidad and Tobago is financed by NSF grant DEB 76-20371. Colwell's work in Chile was supported by the Ford Foundation and by NSF grant GB 31195; his work in Trinidad and Berkeley was partially financed by an NIH Biomedical Sciences grant and by the Committee on Research at the University of California. INTRODUCTION Terrestrial habitats in the American tropics commonly support several species of birds that feed primarily on nectar. Repeated patterns in the morphology and behavior of coexisting species suggest that certain basic principles are involved in the ecological organization of these as? semblages. Investigation of these princi? ples is facilitated by several factors. Nectar production and nutritional value are pre? cisely measurable. Foraging patterns of birds are easily observed and quantified. The coevolution of bill morphology and flower morphology sets certain limits on the patterns of particular species. Since behavioral interactions between birds are also obvious, it is often possible to infer the effect of interference on resource use. The considerable tactability ofthe bird-flower 779
402 citations
TL;DR: DNA sequencing methods have been used to determine a sequence of about 20 nucleotides at the 3' termini of various 18S (small ribosomal subunit) RNA molecules, and a purine-rich region which exhibits extensive complementarity to the 5' noncoding regions of many eucaryotic mRNAs appears consistently.
359 citations
TL;DR: In this paper, an attempt was made to relate the hardness of cemented tungsten carbide to its microstructure, and the concept of plastic limit analysis was used to evaluate the effect of the continous carbide phase on the hardness in WC-Co alloys.
328 citations
TL;DR: The results indicate that patients with unstable angina pectoris can be managed acutely with intensive medical therapy, including the administration of propranolol and long-acting nitrates in pharmacologic doses, with adequate control of pain in most patients and no increase in early mortality or myocardial infarction rates.
Abstract: A prospective randomized study comparing intensive medical therapy with urgent coronary bypass surgery for the acute management of patients with unstable angina pectoris was carried out by nine cooperating medical centers under the auspices of the National Heart, Lung, and Blood Institute. Between 1972 and 1976, a total of 288 patients were entered into the study. All patients had transient S-T or T wave changes, or both, in the electrocardiogram during pain; 90 percent had pain at rest in the hospital, and 76 percent had multivessel coronary disease. The medically and surgically treated patients were comparable with respect to clinical, electrocardiographic and angiographic characteristics and left ventricular function. During the total study period, the hospital mortality rate was 5 percent in the surgical group and 3 percent in the medical group (difference not significant). The rate of in-hospital myocardial infarction was 17 and 8 percent in the respective groups (P In the 1st year after hospital discharge class III or IV angina (New York Heart Association criteria) was more common in medically than in surgically treated patients with one vessel disease (22 percent versus 3 percent, P The results indicate that patients with unstable angina pectoris can be managed acutely with intensive medical therapy, including the administration of propranolol and long-acting nitrates in pharmacologic doses, with adequate control of pain in most patients and no increase in early mortality or myocardial infarction rates. Later, elective surgery can be performed with a low risk and good clinical results if the patient's angina fails to respond to intensive medical therapy.
311 citations
TL;DR: Evidence is provided that long-term alcohol consumption, in the absence of malnutrition, produces morphological damage to the central nervous system.
Abstract: Golgi methods were used to examine the hippocampus of laboratory mice that received alcohol-containing or control diets for 4 months followed by a 2-month alcohol-free period. Long-term alcohol consumption resulted in a significant loss of dendritic spines on hippocampal pyramidal cells and dentate granule cells. This study provides evidence that long-term alcohol consumption, in the absence of malnutrition, produces morphological damage to the central nervous system.
284 citations
TL;DR: Although it constitutes a primer on the subject, it does attempt to deal with inconsistencies in the current meager knowledge of the physical characteristics of urolithiasis to make future work in the field susceptible to analysis by conventional physical theory.
268 citations
TL;DR: In this article, the Schmertmann strain factor method was used for the prediction of settlement over sand and made suggestions for several modifications to the method that should usually result in improved vertical strain distribution and settlement predictions under long footings.
Abstract: Studies by the writers have added further insight to the Schmertmann strain factor method for the prediction of settlement over sand. The writers now make suggestions for several modifications to the method that should usually result in improved vertical strain distribution and settlement predictions under long footings.
267 citations
TL;DR: Recurrent focal epileptiform discharge caused by cortical injection of iron salts suggests that the development of human posttraumatic epilepsy may depend, in part, on the neurochemical alterations induced by the principal metallic ions found in whole blood.
Abstract: A single injection of 5 or 10 microliters of ferrous or ferric chloride into rat or cat sensorimotor cortex resulted in chronic recurrent focal paroxysmal electroencephalographic discharges as well as behavioral convulsions and electrical seizures. Recurrent focal epileptiform discharge caused by cortical injection of iron salts suggests that the development of human posttraumatic epilepsy may depend, in part, on the neurochemical alterations induced by the principal metallic ions found in whole blood.
TL;DR: Recurrent focal epileptiform discharges caused by cortical injection of iron salts suggests that the development of human posttraumatic epilepsy may depend, in part, on neurochemical alterations induced by the principal metallic ions found in whole blood.
Abstract: A single injection of 5 or 10 microliters of ferrous or ferric chloride into rat or cat sensorimotor cortex resulted in chronic recurrent focal paroxysmal electroencephalographic discharges as well as behavioral convulsions and electrical seizures. Iron-filled macrophages, ferruginated neurons, and astroglical cells surrounded the focus of seizure discharge. Recurrent focal epileptiform discharges caused by cortical injection of iron salts suggests that the development of human posttraumatic epilepsy may depend, in part, on neurochemical alterations induced by the principal metallic ions found in whole blood.
TL;DR: Present HRP data suggest that the cells of origin of spinothalamic tract fibers were situated in laminae IV, V, and VI, as well as the location of spinal cord cells oforigin of additional ascending tracts.
TL;DR: During the breeding season, the ovary of Fundulus heteroclitus contains follicles of all sizes and continuously ovulates eggs into the ovarian lumen, which responded to added hormones by undergoing the same maturational changes as occurs in vivo, although the extent of hydration was not quite as extensive.
TL;DR: Four hundred mandibular first premolars and 400 second premolars were decalcified, injected with dye, and made transparent to determine the number of root canals, their type, the ramifications of the main root canal, the location ofApical foramina and transverse anastomoses, and the frequency of apical deltas.
Abstract: Two or more canals were found in more than a fourth of the mandibular first premolars examined and in less than 3% o f the mandibular second premolars studied. Four hundred mandibular first premolars and 400 mandibular second premolars were decalcified, injected with dye, and made transparent to determine the number of root canals, their type, the ramifications of the main root canal, the location of apical foramina and transverse anastomoses, and the frequency of apical deltas. The mandibular first premolar had one canal at the apex in 74.0% of the teeth, two canals at the apex in 25.5%, and three canals at the apex in 0.5% of the teeth. The mandibular second premolar had one canal at the apex in 97.5% and two canals at the apex in 2.5% of the teeth.
TL;DR: Hematologic manifestations and the ultrastructure of a platelet-specific microorganism isolated from a dog in Florida were studied and it is suggested that these organisms be classified in the order Rickettsiales.
Abstract: Hematologic manifestations and the ultrastructure of a platelet-specific microorganism isolated from a dog in Florida were studied. The agent was readily transmitted experimentally to adult dogs by intravenous inoculation with infected blood. Parasitemias and concomitant thrombocytopenias were cyclic in that both recurred within relatively constant periods of one to two weeks following experimental infections. Hemorrhage was not a manifestation of the disease even though thrombocytopenias were severe. Microorganisms were visualized by light and electron microscopy. They were observed only in platelets and were composed of single or multiple subunits (morula forms). The microorganisms were ultrastructurally very similar to those reported in Ehrlichia canis infections of dogs and Anaplasma marginale infections of cattle. Microorganisms were surrounded by single membranes which more or less conformed to the external surfaces of subunits that were surrounded by double membranes. From electron microscopic studies, it is suggested that these organisms be classified in the order Rickettsiales.
TL;DR: The authors empirically tested the effects of group size upon the incremental accuracy of an equal-weighted composite judge in three different judgment tasks and found that on average, the majority of the increment gained by aggregating large numbers of judges can be obtained by aggregation three judges.
TL;DR: The fate of bone transplants is delineated by the presentation of general information on the microscopy of autogenousBone transplant repair, the mechanisms of bone allograft rejection, and possible alternatives when autogenous bone is insufficient.
TL;DR: The ABTS method was found to be three times as sensitive as the older o -dianisidine method and correlated highly with those obtained by acid hydrolysis for rabbit liver glycogen.
TL;DR: The administration of haloperidol reduced the number of consistent sequences of food seeking behaviors by intact animals without significantly affecting the efficiency of performance as measured by the numberof nonfood holes visited.
TL;DR: The authors synthesized research from several related areas to produce a model of resistance to persuasion based upon variables not considered by earlier congruity and inoculation models and found that negative criticism of speaker characteristics reduces threat to present attitudes and reduces motivation to counterargue to protect privately held beliefs.
Abstract: This investigation synthesized research from several related areas to produce a model of resistance to persuasion based upon variables not considered by earlier congruity and inoculation models. Support was found for the prediction that the kind of critical response set induced and the target of the criticism are mediators of resistance to persuasion. The more critical acts are focused on arguments presented in a persuasive message, the more likely that the critical act will not be distracting and therefore promote counterarguing which will lead people to be resistant to subsequent persuasive messages arguing on the same side of given attitudinal issue. When criticism is less central to message variables and focuses on speaker and/or delivery characteristics, distraction occurs which decreases the probability of counterarguing and induces people to be vulnerable to forthcoming persuasive messages. This is especially true when negative criticism of speaker characteristics reduces threat to present attitudes and reduces motivation to counterargue to protect privately held beliefs. A completely counterbalanced design employing several manipulation checks was created to rule out competing explanations for differential resistance to persuasion.
TL;DR: Data confirm and extend previous observations that a limited number of cultivable organisms persist in some lesions but their numbers are few, and they do not appear capable of continuing the destruction of tooth structure.
Abstract: After five years, fewer bacteria were found in carious teeth covered with o sealant than were found in teeth that were not sealed. Carious lesions that were covered with a pit and fissure sealant for five years yielded bacterial cultures that were predominantly negative. Sixteen of 18 test sites judged to have active caries in 1972 were found inactive in 1977; ten of 12 sites suspected to have caries in 1972 were deemed to have inactive cariesin 1977. Sealant treatment resulted in an apparent 89% reversal from a caries-active to a caries-inactive state. These data confirm and extend previous observations that a limited number of cultivable organisms persist in some lesions but their numbers are few, and they do not appear capable of continuing the destruction of tooth structure.
TL;DR: It is concluded that optical and neural effects combine in normal viewing to produce saccadic suppression, and minimizing the optically originating effects of contour masking and retinal image smear failed to eliminate the considerable impairment of vision that occurs during a saccades.
TL;DR: Dental aging can be used in the same way as epiphyseal fusion, osteon aging, cranial sutures, and changes in the public symphysis that have been used with other contemporary and prehistoric populations.
Abstract: Multiple regression analysis has allowed considerable improvement of age estimates on adult human teeth. Not only were the estimates more precise, but they also involved fewer variables, decreasing the probability of observer error. There was consistent evidence that the second molar (Position 7) was the best to use for histological aging techniques. The reduction in variables to just secondary dentin and root transparency has also resulted in a technique that can be used with some confidence in populations other than the one sampled. Thus, dental aging can be used in the same way as epiphyseal fusion, osteon aging, cranial sutures, and changes in the public symphysis that have been used with other contemporary and prehistoric populations.
TL;DR: A population of rock iguanas, Cyclura carinata, inhabiting Pine Cay in the Caicos Islands was nearly extirpated during the three years following construction of a hotel and tourist facility as mentioned in this paper.
TL;DR: Theoretical expressions for computing resistivity and conductivity mobility of holes as functions of dopant density and temperature have been derived for boron-doped silicon.
Abstract: Theoretical expressions for computing resistivity and conductivity mobility of holes as functions of dopant density and temperature have been derived for boron-doped silicon. The model is applicable for dopant densities from 1013 to 3 × 1018 cm−3 and temperatures between 100 and 400 K. Using a 3-band [i.e. heavy-hole, light-hole and the spin-orbit splitting (SO) band] model, the hole mobility was calculated by properly combining the contributions from scattering by lattice phonons, ionized impurities and neutral impurities. In addition, the effects of hole-hole (h-h) scattering and nonparabolicity of valence bands were taken into account in the mobility formulation. To verify our theoretical calculations, resistivity measurements on nine boron-doped silicon slices with dopant densities from 4.5 × 1014 to 3.2 × 1018 cm−3 were performed for 100 ≤ T ≤ 400 K, using planar square-array test structure. Agreement between our calculated and measured resistivity values was within 6 percent over the entire range of dopant density and temperature studied here. Excellent agreement (within ±5%) between our calculated hole mobility values and those of Wagner [9] was obtained for NA ≤ 1017 cm−3 for boron-doped silicon, while discrepancies were found for boron densities greater than 1017 cm−3. This discrepancy is attributed to neglecting the effect of deionization of boron impurities at higher dopant densities by Wagner (i.e. assuming hole density is equal to the total boron density).
TL;DR: There is uncertainty about the significance of coronary diameter reductions previously considered hemodynamically unimportant, and significant changes in resting and reactive hyperemic coronary flows and resting pressure gradients occurred as the length of a given degree of narrowing was increased.
Abstract: The hemodynamic significance of the length of a coronary arterial narrowing is unclear. Accordingly, the influence of the length of a given coronary narrowing on coronary hemodynamic responses was studied in 14 dogs. Recordings were made as short fixed diameter reductions were progressively lengthened to 5, 10 and 15 mm by the addition of plastic occluders. Resting coronary blood flow decreased and pressure gradients developed across short (snare) narrowings greater than 80 percent (critical stenosis). Short 40 to 60 percent narrowings had no significant resting hemodynamic influence, but increasing their length to 10 and 15 mm consistently resulted in significant pressure gradients and flow reductions. Reactive hyperemic coronary blood flow expressed as repayment of flow debt (after 10 seconds of coronary occlusion) decreased progressively as these narrowings were lengthened. The effect of 15 mm long narrowings on resting and reactive hyperemic flows was similar to that of short 90 percent narrowings. These data indicate that there is uncertainty about the significance of coronary diameter reductions previously considered hemodynamically unimportant. In our studies, significant changes in resting and reactive hyperemic coronary flows and resting pressure gradients occurred as the length of a given degree of narrowing was increased.
TL;DR: The 1st New World mosaic is described, in Bahia, Brazil, at least 2 ponerines, 8 dolichoderines, and 2 myrmicines are dominant ants and usually distributed inter se in a mosaic, which differs from Old World mosaics in having dolICHoderines and ponerine functioning as dominants and in the absence of dominant formicines.
Abstract: All previously described tropical ant mosaics have occurred in the Old World. In Bahia, Brazil, at least 2 ponerines, 8 dolichoderines, and 2 myrmicines are dominant ants and usually distributed inter se in a mosaic: the 1st New World mosaic is described. This differs from Old World mosaics in having dolichoderines and ponerines functioning as dominants and in the absence of dominant formicines. Continental drift is invoked in partial explanation and the radiation of ants seen as a pre-Tertiary event in the 1st instance. It is likely the mosaic has a profound effect upon the distribution of tree crop pests, notably in cocoa.