Showing papers by "University of Maryland, Baltimore County published in 1975"
TL;DR: The Overcorrection procedures reduced the scavenging of all 4 retardates to a near zero level within 1 week where it remained for the duration of the study, and the results of biweekly stool specimens showed that all three coprophagic residents were free of parasites during the Overcor correction condition.
115 citations
99 citations
01 Jun 1975-Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology
TL;DR: Chemoreceptors classed as contact receptors on a morphological basis were responsive to vapors of normal food substances and adaptation of the receptor was observed prior to contact with the stimulus.
Abstract: Gustatory chemoreceptors on the maxillae ofManduca sexta responded to natural stimuli from distances of up to 600 μm (average is 100 μm). In the lateral sensilla styloconica, at least three of the four known chemoreceptive cells responded, indicating that different compounds could be involved in the stimulus. The medial sensilla did not show a comparable olfactory capability. Thus, chemoreceptors classed as contact receptors on a morphological basis (thick walls, single apical pore) were responsive to vapors of normal food substances. Adaptation of the receptor was observed prior to contact with the stimulus. This has important implications for experiments on gustatory receptors.
95 citations
TL;DR: Relative responding in initial links of concurrent-chain schedules showed that pigeons preferred free to forced choices and informative to uninformative stimuli.
Abstract: Relative responding in initial links of concurrent-chain schedules showed that pigeons preferred free to forced choices and informative to uninformative stimuli. Variable-interval initial links on two lower keys (white) of a six-key chamber produced terminal links on either two upper-left keys (blue and/or amber) or two upper-right keys (green and/or red). Terminal.links in which pecks on either of two lit keys produced fixed-interval reinforcement (free choice) were preferred to links with only one lit fixed-interval key available (forced choice). Terminal links with different key colors correlated with concurrent fixed-interval reinforcement and extinction (informative stimuli) were preferred to links with these schedules operating on same-color keys (uninformative stimuli). Scheduling extinction for one of the two free-choice keys assessed preference for two lit keys over one lit key, but confounded number with whether stimuli were informative. Fixed-interval reinforcement for both keys in each terminal link, but with different-color keys in one link and same-color keys in the other, showed that preference for informative stimuli did not depend on stimulus variety. Preferences were independent of relative responses per reinforcement and other properties of terminal-link performance.
90 citations
TL;DR: The results confirm and extend previous observations by Hirst that influenza C receptors differ from receptors for myxoviruses and suggest they do not contain sialic acid, and conclude that “influenza C” lacks an α-neuraminidase.
80 citations
71 citations
TL;DR: Young observers were challenged to induce a marked monocular accommodative response to a relatively weak accommodative stimulus by placing a-9 diopter contact lens on the eye, and three of four subjects achieved criterion.
Abstract: Young observers were challenged to induce a marked monocular accommodative response to a relatively weak accommodative stimulus by placing a-9 diopter contact lens on the eye. At first, observers could not produce the desired response, but with training, three of four subjects achieved criterion. Both a voluntary accommodative response and a response to an adequate accommodative stimulus were apparently involved. The voluntary component of the response could be demonstrated by having the observers repeat the task in total darkness.
57 citations
TL;DR: Two studies were conducted to test the hypothesis that physically attractive American females are more assertive than physically unattractive females, and a trend emerged with physically attractive females evidencing greater assertiveness than their less physically attractive counterparts.
Abstract: Summary Two studies were conducted to test the hypothesis that physically attractive American females are more assertive than physically unattractive females. Highly physically attractive and unattractive females were compared with regard to their response to impolite behavior on the part of the experimenter and in regard to the assertiveness dimension of Borgatta's Behavioral Self Rating Form. Physically attractive females were found in both studies to respond more quickly to correct the impoliteness of the experimenter. While there was no difference in the first study between females high as compared to low in physical attractiveness on the Borgatta measure of assertiveness, a trend emerged in the second study with physically attractive females evidencing greater assertiveness than their less physically attractive counterparts.
57 citations
34 citations
TL;DR: The behavior of subjects varied, in part, as a function of reinforcer magnitudes provided for the confederate, and a changeover button was introduced that allowed the subject to eliminate the payoff difference without reducing her own earnings.
Abstract: College-student subjects, who were paired with a confederate, chose to respond either independently or cooperatively for money reinforcers. The subject's relative preference for cooperation was assessed by a procedure (analogous to the psychophysical method of limits) in which response choice was monitored as reinforcer magnitude for one response mode was systematically varied while the other remained constant. Relative preference for cooperation was assessed when the confederate's payoff for cooperation was greater than the subject's (Experiment I) and when the confederate's payoff for independent responding was less than the subject's (Experiment II). For some subjects, changes in the confederate's reinforcer magnitudes resulted in shifts in relative preference for cooperation, which reduced the earnings differences, even though these preference shifts reduced the subject's absolute earnings. For those subjects for whom within-dyad differences in reinforcer magnitude produced no effect, a changeover button was introduced that allowed the subject to eliminate the payoff difference without reducing her own earnings; some subjects used this changeover button to eliminate earnings differences. Thus, the behavior of subjects varied, in part, as a function of reinforcer magnitudes provided for the confederate.
34 citations
TL;DR: The results suggest that polypeptide initiation is rate limiting, particularly below 25 degrees C; whereas above this temperature, elongation or perhaps some other process may be limiting, quite different from those obtained for E. coli and rabbit reticulocyte protein synthesis.
TL;DR: In this article, a random-walk model is proposed by which a single four-parameter compound Poisson process for the residence time of a molecule of tracer in a compartment can fit all of the observed types of specific activity curves.
Abstract: The transport of radioactive tracers and trace pollutants through the body is usually modeled as a multi-compartment linear differential system with constant exchange rates. The specific activity curves must then necessarily be mixtures of exponentials and non-negative integer powers of the time since injection. This is inconsistent with observations on many systems, which exhibit specific-activity curves with either negative powers of time or arbitrary non-integer positive powers of time with an exponential modification (Gamma densities). A physiologically plausible random-walk model is proposed by which a single four-parameter compound Poisson process for the residence time of a molecule of tracer in a compartment can fit all of the observed types of specific activity curves. The parameters have direct interpretations in terms of an age-dependent molecular exchange rate between compartments. Multi-compartment systems can be similarly modeled as a Markov renewal process.
TL;DR: It is shown that influenza replication is inhibited by actinomycin D and α amanitin and migration of viral proteins between host cell cytoplasm and nucleus occurs during the virus replicative cycle.
Abstract: REPLICATION of influenza viruses is believed to require functions provided by the host cell nucleus because first, influenza replication is inhibited by actinomycin D and α amanitin, which prevent transcription of complementary RNA from virion RNA in the first few hours following infection1–4; and second, migration of viral proteins between host cell cytoplasm and nucleus occurs during the virus replicative cycle5–8.
TL;DR: In this paper, the general formulation of axi-symmetric plane strain problems in linear, mechanically homogeneous, isotropic and centro symmetric elastic solids of grade two is given.
Abstract: Given here is the general formulation of axi-symmetric plane strain problems in linear, mechanically homogeneous, isotropic and centrosymmetric elastic solids of grade two. The definition of a plane strain axi-symmetric state of stress is presented, and the necessary and sufficient conditions to achieve it are derived. The general axi-symmetric displacement vector is found, several problems are considered and the reduction of all results to the corresponding classical solutions is discussed.
TL;DR: In this paper, the authors extended the results obtained by the author and others concerning observation and prediction problems for the one-dimensional heat equation to diffusion processes governed by Lu: = (pux)x − qu.
TL;DR: L Laboratory studies show that different photoperiods induce diapause in northern (Vermont) and southern (Maryland) larval strains of the butterfly Limenitis archippus, suggesting that larval diAPause is under the control of multiple genes.
TL;DR: The purpose of this paper is to suggest some of the hypothetical steps by which monomorphic mimics may have evolved from butterflies with non-mimetic phenotypes.
Abstract: Wing color patterns in Lepidoptera often exhibit remarkable divergence in closely related forms. Numerous species are polymorphic, whereas others possess seasonal or geographic differences in coloration. Related butterflies may possess quite different wing patterns, particularly when only certain species, sexes, or forms within a group are involved in mimicry complexes. Such differences are assumed to result from selective processes operating in the natural environment. Determining just how mimetic forms arise from non-mimetic ones has been the object of much research in the field of ecological genetics (Ford, 1945, 1953; Clarke and Sheppard, 1959a, b ; 1960a, b, c; Fisher, 1958; Sheppard, 1959, 1961; Mayr, 1963; Wickler, 1968; Turner, 1970) . Most studies have dealt with polymorphic mimicry complexes. The evolution of monomorphic mimicry (that is, the establishment of a single mimetic phenotype in both sexes over wide areas), has received little attention (Ford, 1971). The purpose of this paper is to suggest some of the hypothetical steps by which monomorphic mimics may have evolved from butterflies with non-mimetic phenotypes. I have carried out an extensive series of reciprocal inter-specific hybrid crosses and backcrosses in the laboratory using eastern species of the Nearctic butterfly genus Limenitis. This Nymphaline group is considered to be monophyletic (Poulton, 1909; Gunder, 1934; Hovanitz, 1949; Chermock, 1950), and yet the wing color-patterns within it are quite diverse, even though all of the species possess similar developmental morphology, life habits, and behavior (Edwards, 1879; Scudder, 1889; Holland, 1905; and Klots, 1951). The two species studied include 1) the banded purple (L. artkemis arthemis Drury), red-spotted purple (L. a. astyanax Fabricius), and their intergrade form (L. a. proserpine Edwards) and 2) the viceroy (L. archippus Cramer). These two species, including the non-mimetic, intergrade, and mimetic forms of L. arthemis, are shown in Figure 1 (in this, and all subsequent figures, the specimens are arranged in sequences which best illustrate their evolutionary transformations) . L. a. arthemis, like most Palearctic Limenitis (Seitz, 1924; Wynter-Blythe, 1957; Higgins and Riley, 1970), is considered to be disruptively colored. It possesses broad medial white bands, crossing its wings and contrasting starkly with its basic dark pigmentation. This pattern optically serves to break up the outline of the butterfly, especially when in flight. L. a. astyanax and L. archippus have lost most,
TL;DR: The succession of morphologic changes in the feeding apparatus (peristome) accompanying conjugation and postconjugant development in the hypotrich Euplotes aediculatus has been examined by scanning electron microscopy (SEM).
Abstract: SYNOPSIS. The succession of morphologic changes in the feeding apparatus (peristome) accompanying conjugation and postconjugant development in the hypotrich Euplotes aediculatus has been examined by scanning electron microscopy (SEM). The details of stomatogenesis inferred from earlier light-microscopic studies of silver-stained preparations have been confirmed and extended.
The elaborate peristome is the dominant surface feature of vegetative Euplotes. In conjugation, the ciliates are joined in their peristomial regions; as the conjugants separate, the old feeding apparatus is seen to be disrupted and partially resorbed. In its place is the crescent-shaped primordium of a new peristome, which develops as part of a general cortical reorganization. This primordium expands anteriorly, unfurling a new crown of ciliary membranelles that soon replaces the remaining preconjugant membranellar band. The resulting “exconjugant peristome'’is characterized by a greatly reduced number of adoral membranelles and the absence of paroral membranelles, buccal cavity, and cytostome. Exconjugants thus cannot feed for 2–3 days, until the missing peristomial components are replaced. This occurs by means of a 2nd cortical reorganization, during which new membranelles, developing from another peristomial rudiment, are added directly to the abbreviated exconjugant set. A new buccal cavity is concurrently sculpted as the primordial depression enlarges, and the cells can resume feeding sometime during the 4th day after separation.
The implications of this mode of stomatogenesis and the nonfeeding condition are discussed, as are the advantages of SEM for studies of ciliate morphogenesis.
TL;DR: Darkness, or defoliation or inversion of segments, therefore, may decrease thymidine incorporation into DNA by effecting reduced auxin levels in stem segments.
Abstract: The short term effect of 11.4 μm indoleacetic acid on the incorporation of (methyl-3H)thymidine into DNA in vegetative tobacco (Nicotiana tabacum cv. Wis. 38) stem segments has been investigated. In segments that are defoliated, inverted, and kept in the dark for 7 hours, indoleacetic acid very rapidly (about 60 minutes) and strikingly initiates thymidine incorporation into DNA. The time required before enough indoleacetic acid (2.8 μm) to enhance thymidine incorporation moves into a segment has been found to be about 35 minutes. The initiation response time for segment tissue that already contains 2.8 μm indoleacetic acid should be no more than about 25 minutes. The rate of labeled thymidine incorporation into DNA is affected by physiological treatments of segments. Moving segments from the light into the dark or defoliating segments or inverting defoliated segments decreases the rate of thymidine incorporation. For segments given all three treatments, indoleacetic acid restores the rate of thymidine incorporation as compared to controls. Darkness, or defoliation or inversion of segments, therefore, may decrease thymidine incorporation into DNA by effecting reduced auxin levels in stem segments.
TL;DR: S N 2 displacement reactions involving halogen atoms are progressively more facile in going from F to I as discussed by the authors and its is suggested that they form part of a general phenomenon in fluorine chemistry.
TL;DR: In this paper, the Arrow-paradox argument for two issues with two alternatives has been shown to be true for any number of issues with a number of alternatives, with the assumption that voters' preferences are "separable or independent" with respect to the several issues that is, each voter can establish a preference ordering of the alternatives in any one issue considered alone.
Abstract: In an article that appeared in a recent issue of this journal, Peter Bernholz shows that "logrolling implies the presence of the Arrow-paradox at least for two issues with two alternatives."' In this note I will present an alternate proof of this point, which is simple and direct and covers any number of issues with any number of alternatives. I will also point out that this argument has been made before indeed, it has previously appeared in this journal. Consider several issues, A, B, etc., each including several alternatives; e.g., al, a2, etc., for issue A. Each distinct combination of alternatives, one from each issue, specifies a "platform," or "policy package," or (to use Bernholz's term) a "complex alternative;" I shall use the term "platform." Consider also an odd number N of voters with strong preferences over the platforms. I assume (as does Bernholz) that voters' preferences are "separable" or "independent" with respect to the several issues that is, each voter can establish a preference ordering of the alternatives in any one issue considered alone. For example, with respect to issue A, voter i prefers a1 to a2 regardless of how other issues may be resolved; put otherwise, he prefers any platform including a1 to the otherwise identical platform including a2. (This assumption certainly is not *University of Maryland, Baltimore County.
TL;DR: Derivatives of Myxococcus xanthus FBt resistant to chloramphenicol arose spontaneously with a frequency of approximately 10−7.5 μg/ml and showed a unique type of phenotypic instability; one of these organisms (FBtCam1r) was characterized and showed resistance was lost after approximately one generation.
Abstract: Derivatives of Myxococcus xanthus FB(t) resistant to chloramphenicol (25 mug/ml) arose spontaneously with a frequency of approximately 10(-7). One of these organisms (FB(t)Cam(1) (r)) was characterized. FB(t)Cam(1) (r) showed a unique type of phenotypic instability. After transfer from medium containing chloramphenicol to medium lacking the drug, resistance was lost after approximately one generation. The loss resulted in a sharp drop in the total number of chloramphenicol-resistant organisms and was not due to segregation of chloramphenicol-susceptible organisms during growth. Cell-free extracts of strain FB(t)Cam(1) (r) converted chloramphenicol to acetyl chloramphenicols in a fashion implicating activity of chloramphenicol acetyltransferase. This activity was lost simultaneously with the loss of chloramphenicol resistance after removal of the drug from cultures. Organisms with a similar phenotype to FB(t)Cam(1) (r) could be produced at high frequencies when strain FB(t) was exposed to low concentrations of chloramphenicol (2 to 5 mug/ml), to 3-acetylchloramphenicol (25 mug/ml), or to 1,3-diacetylchloramphenicol (25 mug/ml). Since strain FB(t) is capable of deacetylating acetyl chloramphenicols, these effects are probably all due to low concentrations of chloramphenicol. In the presence of chloramphenicol, FB(t)Cam(1) (r) produced fruiting bodies and myxospores on fruiting agar; however, glycerol-induced myxospore formation was inhibited. In the absence of the antibiotic, chloramphenicol resistance was maintained by glycerol-induced myxospores.
TL;DR: Of 117 glc mutants tested, 109 form fruiting bodies containing mature myxospores; thus, mutations to the glc phenotype do not normally block myxosphere formation within the fruiting cycle of the organism.
Abstract: Mutants of Myxococcus xanthus FBt unable to form myxospores in response to 05 M glycerol arise spontaneously with a frequency of 1–3×10−5 These mutants are designated glc Ultraviolet mutagenesis increases the frequency to a maximum of 7% of the survivors The reversion frequency following ultraviolet irradiation of spontaneous glc mutants is less than 10−3 Of four glc mutants examined, none form myxospores in response to the alternative inducers, ethylene glycol and dimethyl sulphoxide One glc mutant is induced by 15 M glycerol; strain FBt responds to this glycerol concentration with low efficiency myxospore formation Strain FBt and glc mutants all produce myxospores with low efficiency in response to phenyl ethanol Of 117 glc mutants tested, 109 form fruiting bodies containing mature myxospores; thus, mutations to the glc phenotype do not normally block myxospore formation within the fruiting cycle of the organism
TL;DR: In this article, the decay time of fluorescence of 1-anilino-naphthalene-8-sulfonate bound to phosphorylase b was analyzed.
Abstract: Analysis of the time decay of fluorescence of 1-anilino-naphthalene-8-sulfonate bound to phosphorylase b reveals the presence of two components with different decay times. In glycylglycine buffer, pH 7.0, the addition of the activators AMP or IMP, or the conversion to phosphorylase a results in a preferential decrease in the amplitude of the component of longer decay time, arising probably from a preferential dissociation of 1-anilino-naphthalene-8-sulfonate from the corresponding site as a consequence of a change in molecular state.
TL;DR: Light- and electron-microscopic observations of conjugating pairs and exconjugant cells reveal a process of autophagocytosis that may provide the supplies of energy (and precursors) necessary for postconjugants developmental events.
TL;DR: This is a bibliography of 121 citations most of which, in lieu of annotations, are keyed to abstracts in Child Development Abstracts and Bibliography, Exceptional Child Education abstracts, Mental Retardation Abstracts, and Psychological Abstracts.
Abstract: This is a bibliography of 121 citations most of which, in lieu of annotations, are keyed to abstracts in Child Development Abstracts and Bibliography, Exceptional Child Education Abstracts, Mental ...
TL;DR: The injection operator used by McKean to construct Brownian paths on a Lie group is employed to formulate a class of signal detection problems on matrix Lie groups and a likelihood ratio formula is derived as a function of up-dated observation.
TL;DR: The slow 514-nm absorption changes in Ulva is interpreted as a reflection of relatively slow ionic readjustments across the photosynthetic membranes, and similar difference spectra and the restoration kinetics of the light-on and light -off transient phases indicate that the slow 513-nmabsorption changes reflect the same component(s) and process(es).