Showing papers by "University of Florida published in 1987"
TL;DR: In this paper, the authors present optical-absorption data together with band-structure calculations for the polaron lattice and bipolaron lattice for the highly conducting form of polyaniline, proton-doped polyemeraldine.
Abstract: We present optical-absorption data together with band-structure calculations for the polaron lattice and bipolaron lattice for the highly conducting form of polyaniline, proton-doped polyemeraldine. We show that the polaron-lattice band structure fully accounts for the observed optical transitions. These results are in marked contrast with the electronic structure of other doped conducting polymers, in that only one single broad polaron band appears deep in the gap together with a very narrow band nearly degenerate with the conduction-band edge.
770 citations
TL;DR: The experimental approach is supplemented with theoretical calculations of nitrogen transformations in a shortgrass prairie, which incorporate a wide array of information on decomposer organisms, including their feeding preferences, nitrogen contents, life spans, assimilation efficiencies, productio:assimilation ratios, decomposabilities, and population sizes.
Abstract: Several experimental approaches have been taken to demonstrate the importance of soil fauna in nitrogen mineralization, but there have been difficulties interpreting the results We have supplemented the experimental approach with theoretical calculations of nitrogen transformations in a shortgrass prairie The calculations incorporate a wide array of information on decomposer organisms, including their feeding preferences, nitrogen contents, life spans, assimilation efficiencies, productio:assimilation ratios, decomposabilities, and population sizes The results are estimates of nitrogen transfer rates through the detrital food web, including rates of N mineralization by bacteria, fungi, root-feeding nematodes, collembolans, fungal-feeding mites, fungal-feeding nematodes, flagellates, bacterial-feeding nematodes, amoebae, omnivorous nematodes, predaceous nematodes, nematode-feeding mites, and predaceous mites Bacteria are estimated to mineralize the most N (45 g N m−2 year−1), followed by the fauna (29), and fungi (03) Bacterial-feeding amoebae and nematodes together account for over 83% of N mineralization by the fauna The detrital food web in a shortgrass prairie is similar to that of a desert grassland The shortgrass detrital web seems to be divided into bacteria- and fungus-based components, although these two branches are united at the level of predaceous nematodes and mites
664 citations
TL;DR: This article examined two corollaries of Atiase's differential information hypothesis and found that security prices of large firms anticipate accounting earnings earlier than small firms, and for a given level of ‘unexpected’ earnings, the cumulative abnormal returns of small firms exceed those of large ones.
581 citations
TL;DR: In this paper, the emeraldine base (EB) form of polyaniline can be varied from insulating ( σ −10 ohm −1 cm −1 ) through protonation.
545 citations
TL;DR: This article found that executives in externally controlled firms receive more compensation for performance and less for scale of operation than executives in internally controlled firms. But, they did not consider the performance of the companies.
Abstract: Using a sample of 71 very large manufacturers, this study demonstrated that executives in externally controlled firms receive more compensation for performance and less for scale of operation than ...
509 citations
TL;DR: It is demonstrated that it is possible to change the fermentation products of an organism, such as E. coli, by the addition of genes encoding appropriate enzymes which form an alternative system for the regeneration of NAD+.
Abstract: The genes encoding essential enzymes of the fermentative pathway for ethanol production in Zymomonas mobilis, an obligately ethanologenic bacterium, were inserted into Escherichia coli under the control of a common promoter. Alcohol dehydrogenase II and pyruvate decarboxylase from Z. mobilis were expressed at high levels in E. coli, resulting in increased cell growth and the production of ethanol as the principal fermentation product from glucose. These results demonstrate that it is possible to change the fermentation products of an organism, such as E. coli, by the addition of genes encoding appropriate enzymes which form an alternative system for the regeneration of NAD+.
491 citations
TL;DR: The authors assesses the impact of variables associated with a financial portfolio model (marginal returns, growth, synergy, and uncertainty) and characteristics of the channel relations on the performance of the model.
Abstract: This exploratory study assesses the impact of variables associated with a financial portfolio model (marginal returns, growth, synergy, and uncertainty) and characteristics of the channel relations...
443 citations
TL;DR: The Robinson, Faris, and Wind buyclass framework has been called one of the most useful concepts in organizational buyer behavior, yet the entire buyclass model has received little empirical attention.
Abstract: The Robinson, Faris, and Wind buyclass framework has been called one of the most useful concepts in organizational buyer behavior, yet the entire model has received little empirical attention. Part...
415 citations
TL;DR: In this article, a review of the literature on the dynamics of forest tree recruitment, growth and mortality in natural tropical forests is presented, showing that annual mortality is between 1% and 2% and is independent of size class in trees > 10 cm dbh.
Abstract: Published work on the dynamics of forest tree recruitment, growth and mortality in natural tropical forest is reviewed. In most forests studied, annual mortality is between 1% and 2% and is independent of size class in trees >10 cm dbh; mortality is negatively correlated with growth rate and crown illumination; growth rate is highly variable between individual trees, but shows strong autocorrelation between successive measurements on the same tree. Differences in the rate of dynamic processes can be detected between some species at a site, but data are presently insufficient to determine whether these differences are preserved at other sites where the species occur. None of the studies discussed are of sufficient duration to permit us to draw any conclusions about the equilibrium or non-equilibrium of floristic composition.
404 citations
TL;DR: Habitat corridors have become popular in land-use plans and conservation strategies, yet few data are available to either support or refute their value as discussed by the authors, and Simberloff and Cox have criticized what they consider an uncritical acceptance of corridors in conservation planning.
Abstract: Habitat corridors have become popular in land-use plans and conservation strategies, yet few data are available to either support or refute their value. Simberloff and Cox (1987) have criticized what they consider an uncritical acceptance of corridors in conservation planning.
Any reasonable conservation strategy must address the overwhelming problem of habitat fragmentation. Although Simberloff and Cox use island analogies to illustrate advantages of isolation, these analogies do not apply directly to problems in landscape planning. Genetics also does not offer unequivocal advice, but the life histories of wide-ranging animals (eg., the Florida panther) suggest that the maintenance or restoration of connectivity in the landscape is a prudent strategy. Translocation of individuals among reserves—considered by Simberloff and Cox a viable alternative to natural dispersal—is impractical for whole communities of species that are likely to suffer from problems related to fragmentation.
Many of the potential disadvantages of corridors could be avoided or mitigated by enlatging cowidor width or by applying ecologically sound zoning regulations. Corridors are not the solution to all of our conservation problems, nor should they be used as a justification for small reserves. But corridors can be a cost-effective complement to the strategy of large and multiple reserves in real-life landscapes.
377 citations
TL;DR: The cereals and grasses, which constitute the most important group of crop plants, have until recently been found to be very recalcitrant to cell culture techniques, and the advances made in cell culture of important members of this group of crops are described.
TL;DR: Although bone marrow transplant recipients had an order-of-magnitude greater risk of nosocomial Aspergillus infection than other immunocompromised hosts, this risk could be eliminated by using HEPA filters with horizontal laminar airflow.
TL;DR: Even though the tactics of attack and defense appear more adult-like with increasing age, the playful targets persist well into adulthood.
Abstract: Play-fighting is often difficult to differentiate from inhibited or immature serious fighting because both may utilize many of the same behavior patterns. In the rat the two behaviors involve different targets of attack. During play-fighting, snout or oral contact is directed at the opponent's nape of the neck, whereas during serious fighting, male residents mostly direct their bites at the intruder's rump. Although similar to those used in serious fighting, the behavior patterns used during play-fighting are modified to achieve the different targets of attack. Even though the tactics of attack and defense appear more adult-like with increasing age, the playful targets persist well into adulthood.
TL;DR: The Nature Conservancy (TNC) has developed an efficient system for inventory and evaluation of "elements-of-diversity" as discussed by the authors, which is used to identify stands that cumulatively encompass the full range of variation within each defined natural community type.
TL;DR: Data on hunting by humans reveals the astonishing range of game species taken by Neotropical human hunters.
Abstract: Anthropologists have collected data on hunting by humans to test a number of different hypotheses, including that of protein limitation (Gross 1975), the ideas on taboos advanced by Ross (1978), the efficiency of different weapons (e.g., Hames 1979), and optimal foraging by humans (e.g., Hawkes et al. 1982). These data reveal the astonishing range of game species taken by Neotropical human hunters.
TL;DR: The empty delta sign can probably be explained on the basis of the rich dural venous collateral circulation, consisting primarily of lateral lacunae, a vascular mesh (dural cavernous spaces), and meningeal venous tributaries.
Abstract: The presence of the empty delta sign on contrast material-enhanced computed tomographic (CT) scans of the brain is considered pathognomonic of sagittal sinus thrombosis (SST); however, a valid explanation for its appearance is lacking, despite several hypotheses. To determine the frequency of the sign and its prognostic significance, 76 reported cases (112 CT manifestations) of SST and SST-related intracranial sinovenous occlusive disease were reviewed. Ten CT signs related to both disease processes were reported; the empty delta sign was the most frequently reported sign (28.6%) of SST. Patients with hemorrhagic infarction and/or the empty delta sign on CT scans had the poorest prognosis. A case illustrative of the empty delta sign is described in which there was engorgement of endothelial- and nonendothelial-lined spaces in the dura mater with hemorrhagic rupture into the dural leaf. The empty delta sign can probably be explained on the basis of the rich dural venous collateral circulation, consisting p...
TL;DR: In this paper, the authors studied the complexity in the lost-year ecology of sea turtles and found that the convergence habitat may carry heavy loads of buoyant material, in-cluding the dispersed food resources of the surface waters.
Abstract: An original difficulty in accepting the idea of a pe- lagic developmental period for sea turtles was to explain how food could be found in reliable supply in the open ocean The uncertainty that this introduced was removed when I belatedly came to appreciate theprevalence and diversity of convergences where downwelling gathers and aligns buoyant material, in- cluding the dispersedfood resources of the surface waters. Thus, it now seems clear that an essential factor in the survival of young sea turtles-and of other elements of the epipelagic, open-oceanfauna as well-is the accessibility of afront, where inanimate debris and any floating animal or plant will be gathered in This new evidence of complexity in the lost-year ecology of sea turtles has important implications for their conservation and management. It is now obvious that when young cultured sea turtles are released in so-called head-starting projects, the release sites ought to be chosen with the greatest care. Shores located at a distance from any major current or its eddy ought to be avoided It is also necessary to avoid release localities where the convergence habitat may carry heavy loads of pol- lutant& Results of the present work reveal an urgent need for further study of sea turtle life cycles, with special attention to their developmental ecology. The growing evidence for a more pro- tracted pelagic stage, during which the juvenile turtles are pas- sive migrants in fronts that are increasingly invaded by debris
TL;DR: In this paper, an extended Microcomputer-Based Laboratory (MBL) experience has been shown to be effective in improving middle-school students' graphing skills, and a treatment period as short as a single class period with a motion MBL unit was sufficient for high school physics students to improve their comprehension of distance and velocity graphs when compared with a pencil-and-paper graph construction control treatment.
Abstract: Extended Microcomputer-Based Laboratory (MBL) experience has been shown to be effective in improving middle-school students' graphing skills. This study reports evidence that a treatment period as short as a single class period with a motion MBL unit was sufficient for high school physics students to improve their comprehension of distance and velocity graphs when compared with a pencil-and-paper graph-construction control treatment. Most of the improvement appears to be attributable to the real-time graphing feature of the MBL. A delay of only 20–30 seconds in displaying the graphed data inhibited nearly all of the learning.
TL;DR: In this article, the first numerical results using two extended coupled cluster models that include triple excitations were reported and compared to full CI for several systems, and the results showed that these methods are superior to CCSDT-1 when the reference function is poor, such as in bond breaking cases.
TL;DR: One hundred thirty-four patients with advanced head and neck cancer were treated with radical surgery and postoperative radiation therapy between October 1964 and October 1984 and found 4 factors to be significantly important for predicting disease control above the clavicles.
Abstract: One hundred thirty-four patients with advanced head and neck cancer were treated with radical surgery and postoperative radiation therapy between October 1964 and October 1984. All patients had greater than or equal to 2 years and 84% had greater than or equal to 5 years of follow-up. All patients included in the study were scheduled to receive continuous-course irradiation following a major cancer operation for previously untreated squamous cell carcinoma of the oral cavity, oropharynx, hypopharynx, or larynx and began radiation treatment less than or equal to 3 months after the surgical procedure. Ninety-six percent had AJCC pathologic Stage III or IV cancer, and all were without evidence of gross disease at the start of irradiation. The majority of recurrences above the clavicles occurred in the primary field (84%) as opposed to the posterior strip (8%) or low neck (8%). Based on multivariate analysis and tabular comparisons, 4 factors were found to be significantly important for predicting disease control above the clavicles: (a) Surgical margin (5-year actuarial control with invasive cancer at the margin, 53%, versus 81% with negative margins, p = .009). Patients with close margins or in situ cancer at the margins had the same rate of control as those with negative margins. (b) Primary site (oral cavity, 64%, versus other sites, 83%; p = .029). (c) Neck Stage (N0-1 versus N2-3). (d) Number of indications for irradiation--for example, bone invasion, multiple positive nodes, perineural invasion (1-3 indications, 85%, versus greater than or equal to 4, 62%; p = .06). The rate of disease control above the clavicles did not correlate well with AJCC pathologic stage: Stage I-II, 67%; Stage III, 81%; Stage IVA (T1-3, N2-3A), 68%; Stage IVB (T4 and/or N3B), 80%. The interval between surgery and the start of irradiation (range 1-10 weeks) also was not prognostically important, even with stratification by tumor dose, surgical margin, and number of indications for irradiation. At 5 years, the actuarial survival rate was 33% for the entire group; for patients with invasive cancer at the margin, the survival rate was approximately half that of those whose margins were free of invasive cancer (17% versus 37%). Based on multivariate analysis, 2 factors were found to significantly increase the probability of death due to cancer: (a) neck Stage (N0-1 versus N2-3); (b) extension of tumor from the primary site into the skin or soft tissues of the neck.(ABSTRACT TRUNCATED AT 400 WORDS)
TL;DR: It is suggested that increased body weight provides partial protection against osteopenia in the long bones of OVX rats, however, it is important to note that this protective effect is only partial and that marked oste Openia develops in theLong bones ofOVX Rats regardless of body weight.
Abstract: Bilateral ovariectomies or sham surgeries were performed in female Sprague Dawley rats that were 78 days of age and weighed an average of 210 g. Food was available ad libitum to the control rats and to a group of ovariectomized rats (obese OVX). The food consumption of a second group of ovariectomized rats (weight-matched OVX) was restricted to match their body weights to those of the control rats. All rats were sacrificed at 14 weeks postovariectomy. Radioimmunoassay of terminal serum estradiol confirmed the success of ovariectomy. The estradiol concentration in control rats was 24.9±20.2 pg/ml, whereas the hormone was undetectable (<10 pg/ml) in both groups of OVX rats. The final body weights of control and weight-matched OVX rats were nearly identical (∼260 g). In contrast, obese OVX rats weighed significantly more than both of the above groups (∼320 g,P<0.001). The proximal tibia and lumbar vertebra were processed undecalcified for quantitative bone histomorphometry. Tibial trabecular bone volume (TBV) was determined to be 17.6±4.5%, 7.9±5.3%, and 3.6±3.1% for the control, obese OVX, and weight-matched OVX groups, respectively. Tibial TBV for both OVX groups was significantly less than the control value (P<0.001). The difference in tibial TBV between obese OVX and weight-matched OVX rats was also statistically significant (P<0.02). Histologic indices of bone resorption and formation were indicative of increased bone turnover in the proximal tibia of both OVX groups. In comparison to control rats, both groups of OVX rats exhibited a strong trend for a reduction in vertebral TBV, but no significant differences were observed among the three groups. Our results suggest that increased body weight provides partial protection against osteopenia in the long bones of OVX rats. However, it is important to note that this protective effect is only partial and that marked osteopenia develops in the long bones of OVX rats regardless of body weight.
TL;DR: In this article, stable oxygen and carbon isotopic profiles from Recent specimens of Spisula solidissima and Placopecten magellanicus collected off the Virginia coast are used to calibrate annual temperature-controlled cycles in the δ18O profile and shell growth characteristics.
TL;DR: Rostral AGm can be viewed as a multimodal association area with strong ties to the motor system and bears certain striking resemblances to the frontal eye field, supplementary motor, and arcuate premotor areas of monkey cortex.
TL;DR: Results indicate an anxiogenic action for CRF in the social interaction test of anxiety in rats, and the possible mechanisms of the behavioral effects of CRF are discussed.
TL;DR: This paper shows how the image algebra suggests a general-purpose cellular pyramid array processor for real time image processing tasks and demonstrates how algebraic techniques can be used to develop systematic methods for deriving parallel algorithms.
TL;DR: Advances in the understanding of the developmental ecology of sea turtles shed new light on the impact of buoyant wastes on the juvenile stages of these species.
TL;DR: The observed high complete response rates in patients in all stages and the high survival rates suggest irradiation plus cisplatin therapy offers an important therapeutic gain over radiation therapy alone for invasive cancer of the bladder.
Abstract: Seventy patients with muscle-invading bladder carcinoma (clinical stages T2 to T4) who were not candidates for cystectomy were treated with combined cisplatin and full-dose external-beam radiation on a multi-institutional prospective protocol from 1980 through 1985. Thirty-six patients are alive, all but three without evidence of cancer. The complete response rate is 77% in the 62 patients completing planned irradiation and 70% for all patients. Among the complete responders, 73% are currently maintained, and this group has a significantly higher four-year survival than those not having a complete response and those with recurrence of disease—57% vs 11%. The observed high complete response rates in patients in all stages and the high survival rates suggest irradiation plus cisplatin therapy offers an important therapeutic gain over radiation therapy alone for invasive cancer of the bladder. These results encourage further evaluation of combining cisplatin-based, multidrug chemotherapy with irradiation in patients with locally very-advanced bladder tumors who are not suited for surgery. ( JAMA 1987;258:931-935)
TL;DR: New information is highlighted about the life cycle of S. neurona and the literature regarding diagnosis, clinical signs, and treatment of EPM, considered a treatable disease, although the response to antimicrobial treatment often is incomplete.
Abstract: Equine protozoal myeloencephalitis (EPM) is a disease that produces neurologic signs of brain or spinal cord dysfunction. The causative organism is believed to be a Sarcocystis species of protozoa. A definitive diagnosis can only be made on histopathology of affected spinal cord or brain. No preventive measures or documented treatment is available at this time for suspected cases of EPM.
TL;DR: In the Troodos ophiolite as discussed by the authors, two plagiogranites from one sample yield U-Pb dates of 90.3 ± 0.7 and 92.4 ± 0.7 Ma.
Abstract: Zircon populations from two plagiogranites in the plutonic section of the Troodos ophiolite yield U-Pb dates between 90.3 ±0.7 and 92.4 ±0.7 Ma. Zircons from one of the two samples yield U-Pb dates of 90.3 ±0.7 and 92.1 ±0.7 Ma. This difference is greater than our analytical error, and the zircons are therefore considered to be slightly discordant. Two fractions from another sample are internally and externally concordant and have an average date of 91.6 ±1.4 Ma. This date is adopted as the age of plagiogranite crystallization. The plutonic section of the Troodos ophiolite is complex in that several generations of intrusion can be identified. The plagiogranites occur at the top of the intrusive section and represent fractionated residua of magma chambers related to the lower pillow lavas. They are possibly slightly older than small ultramafic layered complexes that represent the final intrusive episode within the Troodos ophiolite. There is good agreement between our results and the ages of radiolaria which occur in umbers intercalated with the upper pillow lavas of Troodos (Blome and Irwin, 1985). This shows that the 75 to 85 Ma K-Ar dates on the lavas and sheeted dikes (Desmet et al., 1978; Delaloye and Desmet, 1979; Delaloye et al., 1980; Staudigel et al., 1986) represent age resetting unrelated to ophiolite formation. The Troodos U-Pb zircon ages are slightly lower than U-Pb zircon ages from the Samail ophiolite in Oman, which vary between 93.5 and 97.9 Ma and average 95 Ma (Tilton et al., 1981). The small difference in age between the Troodos and the Samail ophiolites and the geochemical similarities of basalts from both complexes to island-arc volcanic rocks imply that a 3000-km axis of rift-related island arcs formed between 91 and 98 Ma. Emplacement of the ophiolites followed during the early Maastrichtian.
TL;DR: Preterm infants may become apneic during the immediate postoperative period, and breathing patterns of 47 preterm infants less than 60 weeks postconception with pneumocardiograms before and after general inhalational anesthesia are studied.
Abstract: Preterm infants may become apneic during the immediate post-operative period. To define this risk, the authors studied prospectively the breathing patterns of 47 preterm infants less than 60 weeks postconception with pneumocardiograms before and after general inhalational anesthesia. Eighteen infants (37%) had prolonged apnea (greater than 15 s) postoperatively, and an additional seven infants (14%) had short apnea (6-15 s) postoperatively. An infant's risk of prolonged and short postoperative apnea was related to a young postconceptional age (P less than 0.05) and to a history of necrotizing enterocolitis (P less than 0.01). Furthermore, as the postconceptional age of the infant increased, the risk of postoperative apnea decreased proportionately (P less than 0.025). Among the 18 infants with prolonged apnea, 83% experienced multiple apneic episodes. Manual stimulation was required in order for breathing to return in 13 (72%) of the infants. Breathing resumed spontaneously in four (22%) of the infants, and one infant required mechanical ventilation due to repeated prolonged apnea. The first apneic event occurred within 2 h postoperatively in 13 of the infants (72%); the remaining five infants (28%) had their initial apneic episode as late as 12 h after operation. The postoperative time to the last prolonged apneic event was inversely related to the postconceptional age (P less than 0.01, r = -0.70) and extended up to 48 h postoperatively. The preoperative pneumocardiogram was not a reliable test for predicting postoperative apnea (sensitivity 56%, specificity 83%).(ABSTRACT TRUNCATED AT 250 WORDS)