Cognitive factors in biofeedback therapy

The role that the client's cognitions(viz., his self-statements and images) play in each of the various phases of biofeedback training is examined. Biofeedback training is conceptualized as including three phases: initial conceptualization, skills-acquisition and -rehearsal, and transfer of treatment. Cognitive-behavior modification procedures to alter or employ the clients' cognitions at each of these phases of treatment are described. A cognitive theory of self-control is offered, postulating a three-stage mediational change process whereby:(1) the client must become an observer of his behavior and physiological responses;(2) this recognition becomes the cue to emit incompatible cognitions and behaviors; and, finally,(3) the content of the client's cognitions following change influences the generalization and persistence of treatment effects. The implications of this theory for biofeedback training are discussed.     

Kinetics of Manganese Uptake by Intact Citrus Seedlings

Uptake of manganese by intact citrus seedlings can be represented by three phases of a single, multiphasic isotherm in the range 10^?8M–2× 10^?4M. The phases are separated by marked jumps and the kinetic constants increase upon transition to higher phases.     

DURATION OF MITOSIS AND SEPARATE MITOTIC PHASES COMPARED TO NUCLEAR DNA CONTENT IN ERYTHROBLASTS OF FOUR VERTEBRATES

The passage of a wave of tritiated. thymidine-labelled cells through each of the phases of mitosis is analysed in erythroblasts of four vertebrates species, selected because of their widely differing diploid DNA content. Mitotic time (t_m) and relative durations of separate mitotic phases as well as that of the G₂ period are thus accurately determined. Mean duration of t_m appears to vary according to the species specific DNA amount. This relation is approximately the same as for S, for G₁ and for the generation time, which have been previously determined.     

Reliability of the resorcinol method for identifying isomorphic phases in the Gigartinaceae (Rhodophyta)

The Gigartinaceae are economically important because the carrageenans in this family are used for a variety of purposes including food stabilizers, food substitutes, pharmaceutical applications and cosmetics. The resorcinol method takes advantage of the different carrageenans found in life history phases in this family to identify nonreproductive phases, and consequently, a better understanding of the biology of this economically important family is possible. This study investigates sources of variability that could affect the accuracy of the resorcinol method in identifying phases within the Gigartinaceae. Vegetative disks of Iridaea splendens from different areas of the blade and disks containing reproductive structures all reacted consistently to the resorcinol reagent. The minimum size and testing conditions required to reliably identify phases at the germling stage of I. splendens were determined. Phases of I. splendens cannot be identified if blades are stored in 3% formaldehyde in seawater. Phases of I. splendens, I. lineare, I. heterocarpa, Rhodoglossum californicum and R. affine can be identified reliably at different times of the year. Manipulations of the resorcinol method improved its accuracy in identifying phases of Iridaea cornucopiae and Gigartina exasperata but the high percent of G. exasperata misidentified demonstrates that it cannot be assumed that the current resorcinol method works for all taxa in the Gigartinaceae.     

The Roles of Structural Order and Intermolecular Interactions in Determining Ionization Energies and Charge‐Transfer State Energies in Organic Semiconductors

The energy landscape in organic semiconducting materials greatly influences charge and exciton behavior, which are both critical to the operation of organic electronic devices. These energy landscapes can change dramatically depending on the phases of material present, including pure phases of one molecule or polymer and mixed phases exhibiting different degrees of order and composition. In this work, ultraviolet photoelectron spectroscopy measurements of ionization energies (IEs) and external quantum efficiency measurements of charge‐transfer (CT) state energies (E_CT) are applied to molecular photovoltaic material systems to characterize energy landscapes. The results show that IEs and E_CT values are highly dependent on structural order and phase composition. In the sexithiophene:C₆₀ system both the IEs of sexithiophene and C₆₀ shift by over 0.4 eV while E_CT shifts by 0.5 eV depending on molecular composition. By contrast, in the rubrene:C₆₀ system the IE of rubrene and C₆₀ vary by ≤ 0.11 eV and E_CT varies by ≤ 0.04 eV as the material composition varies. These results suggest that energy landscapes can exist whereby the binding energies of the CT states are overcome by energy offsets between charges in CT states in mixed regions and free charges in pure phases.     

Effect of double-bonds on bimolecular films in membrane models

The effect of unsaturation (especially bys cis-bonds) is studied on bimolecular films of saturated and unsaturated alkylammonium ions and alkanols between silicate surfaces as model systems for lipid layers in membranes. Three types of structures are observed: all-trans-blocks, kink-blocks and gauche-blocks. The knowledge of the sequence of these phases and their thermal transitions provides detailed deductions about the role of double-bonds. cis-Unsaturated chains are taken up in bimolecular films as isomers with cis-trans-gauche conformation. This conformation makes the shape of the chain similar to that of kinked chains (chains with gauche-trans-gauche (—) conformation) and enables the incorporation into the film without greater sterical hindrance. The experimental results are in good agreement with X-ray measurements on biological membranes by Engelman (Engelman, D.M., J. Mol. Biol. 47, 115–117 (1970) and 58, 153–165 (1971)).Increasing the concentration of cis-chains decreases the transition temperature of the kink-blocks into gauche-blocks. The variation of the transition temperature with concentration of cis-unsaturated chains in the model system is similar to that observed for Escherichia coli membranes. It is suggested that phase changes in biomembranes are of the same nature: transition of kink-block analogues as ordered phases into gauche-block assemblies as less ordered phases.     

First-principles investigations on structural stability,elastic and electronic properties of Co7M6 (M= W,Mo, Nb) µ phases

The structural, elastic and electronic properties of Co₇M₆ (M?=?W, Mo, Nb) μ phases were investigated by first-principles calculations based on the density functional theory (DFT). The calculated cohesive energy indicates that Co₇M₆ (M?=?W, Mo, Nb) μ phases are thermodynamically stable. Besides, Co₇W₆ owns a higher structural stability than that of Co₇Mo₆ and Co₇Nb₆. The obtained elastic constant demonstrates that Co₇M₆ (M?=?W, Mo, Nb) are mechanically stable. With Voigt-Reuss-Hill (VRH) approximation, the elastic bulk modulus (B), shear modulus (G), Young's modulus (E) and Poisson's ratio (ν) were derived. The ductility and plasticity as well as the elastic anisotropy of the three phases were discussed in details. Finally, the density of states and charge density difference were also analysed to reveal the underlying mechanism of structural stability and the elastic properties.     

XANES Investigation of Dynamic Phase Transition in Olivine Cathode for Li‐Ion Batteries

Dynamic phase transformation in olivine LiFePO₄ involving formation of one or more intermediate or metastable phases is revealed by an in situ time‐resolved X‐ray absorption near edge structure (XANES) technique. The XANES spectra measured during relaxation immediately after the application of relatively high overpotentials, where metastable phases are expected, show a continuous shift of the Fe K‐edge toward higher energy. Surprisingly, the Fe K‐edge relaxes to higher energies after current interrupt regardless of whether the cell is being charged or discharged. This relaxation phenomenon is superimposed upon larger shifts in K‐edge due to changes in Fe^2+/Fe³⁺ ratio due to charging and discharging, and implies an intermediate phase of larger Fe? O bond length than any of the known crystalline phases. No intermediate crystalline phases are observed by X‐ray diffraction (XRD). A metastable amorphous phase formed during dynamic cycling and which structurally relaxes to the equilibrium crystalline phases over a time scale of about 10 min after cessation of charging/discharging current is consistent with the experimental observations.     

Variations in ozone-sensitivity in relation to cell cycle and ploidy in Saccharomyces cerevisiae

Summary Cyclic variations in resistance to ozone-inactivation were observed during the cell cycle of a haploid strain of Saccharomyces cerevisiae. The lag and G₁ phases showed the highest sensitivity to ozone whereas there was a progressive increase in resistance from the S to G₂ phases as the proportion of dividing cells increased. A related series of S. cerevisiae varying in ploidy from haploid to tetraploid was exposed to ozone. The results demonstrated clearly an enhancement of ozone resistance directly related to the ploidy of the cells.Taken together these data suggest that resistance to ozone is dependent upon the action of an efficient repair mechanism. Similarities and differences between the biological action of ozone and ionizing radiations in S. cerevisiae are discussed.     

A Mathematical Model of Cell Cycle Progression Applied to the MCF-7 Breast Cancer Cell Line

In this paper, we present a model of cell cycle progression and apply it to cells of the MCF-7 breast cancer cell line. We consider cells existing in the three typical cell cycle phases determined using flow cytometry: the G1, S, and G2/M phases. We further break each phase up into model phases in order to capture certain features such as cells remaining in phases for a minimum amount of time. The model is also able to capture the environmentally responsive part of the G1 phase, allowing for quantification of the number of environmentally responsive cells at each point in time. The model parameters are carefully chosen using data from various sources in the biological literature. The model is then validated against a variety of experiments, and the excellent fit with experimental results allows for insight into the mechanisms that influence observed biological phenomena. In particular, the model is used to question the common assumption that a ‘slow cycling population’ is necessary to explain some results. Finally, an extension is proposed, where cell death is included in order to accurately model the effects of tamoxifen, a common first line anticancer drug in breast cancer patients. We conclude that the model has strong potential to be used as an aid in future experiments to gain further insight into cell cycle progression and cell death.     

A New Variant for Mathematical Analysis of Pulse Cytophotometric Data

The staining of DNA by specific fluorochromes provides a suitable method of receiving histograms in a short time by means of pulse cytometry. They represent the proliferative structure of cell populations at a high degree of statistical security. A method for quantitative determination of cell cycle phases (G_1-, S- and G₂ + M-phase) is presented which includes the fraction of cell debris in the calculation procedure. The advantages of this method are the elimination of overlapping between the fraction of debris and cell cycle phases and the quantitative determination of the fraction of cell debris offers the opportunity to get information on cytolytic potencies. Apart from the calculation of the various cell cycle phases the method provides criteria on the adaptation of mathematical analysis to primary data.     

Evaluation of the use of phase-specific gene promoters for the expression of enological enzymes in an industrial wine yeast strain

Summary Genes as POT1, HSP104 and SSA3, which are late expressed in laboratory culture conditions are expressed only during the first few days in microvinifications in wine yeast cells. This effect is probably due to the different growth conditions and leads to useless levels of enzyme activity for a reporter gene. However the ACT1 promoter, which is constitutively expressed in laboratory conditions, produces sufficient amounts of enzyme activity in late fermentation phases.     

Feeding ecology and seasonal diet overlap between Stellifer brasiliensis and Stellifer stellifer in a tropical estuarine ecocline

Seasonal freshwater discharge was important for defining habitat utilization by different ontogenetic phases of Stellifer brasiliensis and Stellifer stellifer along the estuarine ecocline. The middle estuary was important as a nursery and feeding ground for young‐of‐the‐year, and a feeding ground for sub‐adults and adults of both species. These species are zoobenthivorous, but during their life cycle and between different habitats and seasons, their trophic guild can change to opportunist and zooplanktivore. During the late rainy season in the lower estuary, all phases of both species, except juveniles of S. brasiliensis and adults of S. stellifer, showed a niche overlap indicating similarity in prey utilization. The diet composition was qualitatively similar, showing an evident niche overlap of intra and interspecific competition among the Stellifer spp. Although the niches of these species appeared to significantly overlap, some resource partitioning patterns were apparent. The niche overlap was significantly reduced due to the seasonal difference in habitat use and prey consumption along the ecocline of the estuary by different ontogenetic phases. The ingestion of blue nylon fragments by both species was observed and quantified.     

Trophic niche and habitat shifts of sympatric Gerreidae

The diet and mouth growth rates of three Gerreidae species (Eugerres brasilianus, Eucinostomus melanopterus and Diapterus rhombeus) were assessed at different ontogenetic phases (juveniles, sub‐adults and adults) in order to detect allometric growth, and whether they are related to habitat and seasonal changes in the Goiana Estuary, north‐east Brazil. The importance of each prey for each ontogenetic phase was described using the index of relative importance. The three species showed seasonal ontogenetic shifts in diet and allometric growth of mouth morphology. They also had an exclusively zoobenthic diet, comprising mainly Polychaeta, Copepoda, Ostracoda, Gastropoda and Bivalvia. Mouth development showed a possible influence on diet changes for E. melanopterus. Significant interactions (P < 0·01) were detected among seasons, areas and ontogenetic phases for the most important prey for E. brasilianus and E. melanopterus. Diet overlaps are evidence of intra and interspecific competition among gerreids for specific prey. A conceptual model of the competition and seasonal diet shifts among ontogenetic phases of gerreids is given. The sediment ingested due to the feeding mechanisms of Gerreidae species could also partially explain the ingestion of synthetic items observed for all ontogenetic phases, which indicates one of a myriad effects of human activities (e.g. artisanal fishery) in this estuary.     

An insight into spore dispersal of <Emphasis Type="Italic">Ganoderma boninense</Emphasis> on oil palm

The disease of oil palm caused by Ganoderma boninense, although universally referred to as Ganoderma basal stem rot, occurs in three very distinct phases, with basal stem rot only part of the disease cycle. G. boninense also causes a seedling disease and an upper stem rot. An understanding of spore dispersal provides an insight into where spores of G. boninense have a role in the infection process. This role will be discussed in relation to each of these three infection phases. This understanding is a critical component of developing a successful disease control strategy.     

Preparative separation of amino acid enantiomers as N-TFA,O-isopropyl derivatives by continuous countercurrent gas-liquid chromatography

Preparative separation of derivatives of amino acid enantiomers was carried out by a countercurrent gas–liquid chromatography (CCGLC) with chiral liquid phases, N-stearoyl-L -valine tert-butylamide and/or N-stearoyl-L -leucine tert-butylamide. In order to make effective use of these phases and also to lower the viscosity, Apiezon C was added as diluent. Through a repeated operation of a temperature gradient, purities more than 99% of leucine and α-amino butyric acid derivatives were proved to be obtained. © 1993 Wiley-Liss, Inc.     

Flowering biology ofGeonoma irena andG. cuneata var.sodiroi (Arecaceae)

The phenology and flowering of two sympatric understory palms from western Ecuador, until recently regarded as conspecific, is described.Geonoma irena Borchs. flowers throughout the year. Anthesis lasts 11–14 weeks per inflorescence, with overlapping male and female phases. Flowers open in the midmorning, and are visited mainly by meliponid and halictid bees.Geonoma cuneata var.sodiroi (Burret)Skov flowers from December to April, with a distinct peak in Feburary. Anthesis lasts 6–8 days per inflorescence, with non-overlapping male and female phases. Flowers open at dawn, and are visited mainly by drosophilid and sphaerocerid flies. The flowering pattern of the two species match different specific behavioural features of their insect visitors. The study provides an example of how differences in reproductive biology may act as an important barrier to gene flow between related, co-occurring taxa.     

FUNCTIONAL SIMILARITY AMONG ISOMORPHIC LIFE-HISTORY PHASES OF POLYCAVERNOSA DEBILIS (RHODOPHYTA,GRACILARIACEAE) 1

Morphologically identical but different life-history phases of the red alga Polycavernosa debilis (Forsskål) Fredericq and J. Norris showed no conspicuous differences in physiological or ecological performances. The costs and benefits of ploidy level, as measured by net photosynthesis, calorific content, structural makeup and resistance to predation, were not sufficient to result in statistically significant differences (P > 0.05 ANOA) for the various reproductive phases [haploid male or female (including cystocarps) and diploid tetrasporic]. The lack of measurable functional responses leads to two hypotheses: (1) that adaptive ecological-physiological differences between life-history phases are subtle, or (2) that predominantly genetic / reproductive factors are implicated in maintaining isomorphic life-history phases.     

The liquid-ordered phase in sphingomyelincholesterol membranes as detected by the discrimination by oxygen transport (DOT) method

Membranes made from binary mixtures of egg sphingomyelin (ESM) and cholesterol were investigated using conventional and saturation-recovery EPR observations of the 5-doxylstearic acid spin label (5-SASL). The effects of cholesterol on membrane order and the oxygen transport parameter (bimolecular collision rate of molecular oxygen with the nitroxide spin label) were monitored at the depth of the fifth carbon in fluid- and gel-phase ESM membranes. The saturation-recovery EPR discrimination by oxygen transport (DOT) method allowed the discrimination of the liquid-ordered (l _o), liquid-disordered (l _d), and solid-ordered (s _o) phases because the bimolecular collision rates of the molecular oxygen with the nitroxide spin label differ in these phases. Additionally, oxygen collision rates (the oxygen transport parameter) were obtained in coexisting phases without the need for their separation, which provides information about the internal dynamics of each phase. The addition of cholesterol causes a dramatic decrease in the oxygen transport parameter around the nitroxide moiety of 5-SASL in the l _o phase, which at 50 mol% cholesterol becomes ∼5 times smaller than in the pure ESM membrane in the l _d phase, and ∼2 times smaller than in the pure ESM membrane in the s _o phase. The overall change in the oxygen transport parameter is as large as ∼20-fold. Conventional EPR spectra show that 5-SASL is maximally immobilized at the phase boundary between regions with coexisting l _d and l _o phases or s _o and l _o phases and the region with a single l _o phase. The obtained results all _owed for the construction of a phase diagram for the ESM-cholesterol membrane.     

Kinetic heterogeneity of an experimental tumour revealed by BrdUrd incorporation and mathematical modelling

In the present paper we propose a method of analysis of the cell kinetic characteristics of in vivo experimental tumours, that uses DNA-BrdUrd flow cytometry data at various times after the bromodeoxyuridine (BrdUrd) injection and mathematical modelling. The model of the cell population takes into account the cell-cell heterogeneity of the progression rate across cell cycle phases within the tumour, and assumes a strict correlation between the durations of S and G2M phases. The model also allows for a nonconstant DNA synthesis rate across S phase. In addition, the measurement process is modelled, considering the possibility of nonimpulsive labelling and providing a representation of the time course of the bivariate DNA-BrdUrd fluorescence distribution. Sequential DNA-BrdUrd distributions were obtained in vivo from a human ovarian carcinoma transplanted in mice and, for comparison, in vitro from a cell line of the same origin. From these data, that included the fractional density and the mean BrdUrd-fluorescence of BrdUrd-positive cells as a function of the DNA-fluorescence, kinetic parameters such as the potential doubling time (T _pot) and the mean and variance of the transit times in S and G2M phases, were estimated. This study revealed the presence of a substantial heterogeneity in S and G2M phases within the in vivo cell population and of a lower heterogeneity in the in vitro population. Moreover, our analysis suggests a nonnegligible effect of the BrdUrd pharmacokinetics in the in vivo cell labelling.