Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Mathematical Concepts”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 721 records · Page 40Linked to original sources
PubMed1999

The control of partitioning between protein and fat during human starvation: its internal determinants and biological significance.

Human subjects vary in the extent to which their body's protein and fat compartments are mobilized for fuel during starvation. Although an inverse association between the initial adiposity and the contribution of protein as fuel during starvation has been known for nearly a century, interest in the quantitative importance and functional significance of the initial percentage fat as a determinant of biological variation in energy-partitioning between protein and fat (and hence in determining the partitioning characteristic of the individual) is relatively recent. The present paper addresses these issues by revisiting the classic Minnesota experiment of semi-starvation and refeeding from a standpoint of system physiology. In a quantitative analysis of the relationship between the initial body composition (ration FAT0: fat-free mass (FFM)0) and the composition of weight loss (ratio delta FAT: delta FFM) in the thirty-two men in the Minnesota study, the arguments are put forward that the fraction of FFM lost when the fat stores reach total depletion is independent of the initial percentage fat, and that this fraction represents the 'dispensable' component of the protein compartment that is compatible with life (i.e. the protein energy-reserve, rp). The concepts are developed that (1) the initial percentage body fat (which reflects the initial ratio FAT0:FFM0) provides a 'memory of partitioning' which dictates the control of partitioning between protein and fat in such a way that both the protein energy-reserve (rp) and the fat energy-reserve (rf) each complete depletion simultaneously, a strategy that would ensure maximum length of survival during long-term food scarcity, and that (2) variability in the relative sizes of these two energy reserves (i.e. in rf:rp) could, in addition to the initial percentage fat, also contribute to human variability in energy-partitioning. The basic assumptions underlying this re-analysis of the Minnesota data, and the concepts that are derived from it, have been integrated in the simple mathematical model for predicting the partitioning characteristic of the individual. This model is used to explain how variability in the fraction of the protein compartment that could function as an energy reserve (rp) can be as important as the initial percentage fat in determining inter-individual variability in protein-sparing during the early phase of starvation, in fuel partitioning during prolonged starvation, or in the maximum percentage weight loss during starvation. The elucidation of factors underlying variability in the size of the protein energy-reserve may have important implications for our understanding of the pathophysiology of starvation and age-associated susceptibility to muscle wasting, and in the clinical management of cachexia and obesity.

Body Composition↗
PubMed2002

Molecular quantum similarity and the fundamentals of QSAR.

A general overview on quantum similarity and applications to QSAR is presented. The concepts regarding quantum similarity from its theoretical foundation and consecutive development, involving mathematical formulation and similarity measures, are presented and complemented with application examples. The practical part, based on the well-known Crammer 31 steroids set, covers approximate quantum similarity calculations, molecular superposition, and statistics. In this way, the reader will find both basic general information and applicability of quantum similarity.

Animals↗
PubMed1998

That swimsuit becomes you: sex differences in self-objectification, restrained eating, and math performance.

Objectification theory (B. L. Fredrickson & T. Roberts, 1997) posits that American culture socializes women to adopt observers' perspectives on their physical selves. This self-objectification is hypothesized to (a) produce body shame, which in turn leads to restrained eating, and (b) consume attentional resources, which is manifested in diminished mental performance. Two experiments manipulated self-objectification by having participants try on a swimsuit or a sweater. Experiment 1 tested 72 women and found that self-objectification increased body shame, which in turn predicted restrained eating. Experiment 2 tested 42 women and 40 men and found that these effects on body shame and restrained eating replicated for women only. Additionally, self-objectification diminished math performance for women only. Discussion centers on the causes and consequences of objectifying women's bodies.

Adolescent↗
PubMed1998

Symbolic distance between numerosity and identity modulates Stroop interference.

Thirty undergraduates participated in an experiment investigating the effect of the arithmetic difference between stimulus identity and stimulus numerosity in a numerical version of the Stroop task. It was found that digits symbolically close to the enumeration response reliably produced larger interference than digits that were farther from the enumeration response. This semantic distance effect was found with different numerosities (1-9) and different enumeration processes (counting and subitizing), and it increased as a function of numerosity in the subitizing range. These findings suggest that digit identity autonomously activates a magnitude representation organized as a compressed number line.

Adult↗
PubMed2002

What very small numbers mean.

This article presents a theoretical and experimental framework for assessing the biases associated with the interpretation of numbers. This framework consists of having participants convert between different representations of quantities. These representations should include both variations in numerical labels that symbolize quantities and variations in displays in which quantity is inherent. Five experiments assessed how people convert between relative frequencies, decimals, and displays of dots that denote very low proportions (i.e., proportions below 1%). The participants demonstrated perceptual, response, and numerical transformation biases. Furthermore, the data suggest that relative frequencies and decimals are associated with different abstract representations of amount.

Cognition↗
PubMed1987

Attention and learning processes in the identification and categorization of integral stimuli.

The relationship between subjects' identification and categorization learning of integral-dimension stimuli was studied within the framework of an exemplar-based generalization model. The model was used to predict subjects' learning in six different categorization conditions on the basis of data obtained in a single identification learning condition. A crucial assumption in the model is that because of selective attention to component dimensions, similarity relations may change in systematic ways across different experimental contexts. The theoretical analysis provided evidence that, at least under unspeeded conditions, selective attention may play a critical role in determining the identification-categorization relationship for integral stimuli. Evidence was also provided that similarity among exemplars decreased as a function of identification learning. Various alternative classification models, including prototype, multiple-prototype, average distance, and "value-on-dimensions" models, were unable to account for the results.

Attention↗
PubMed2005

Defensive pride and consensus: strength in imaginary numbers.

Failure (Study 1) and attachment separation thoughts (Study 2) caused exaggerated consensus estimates for personal beliefs about unrelated social issues. This compensatory consensus effect was most pronounced among defensively proud individuals, that is, among those with the combination of high explicit and low implicit self-esteem (Study 1) and the combination of high attachment avoidance and low attachment anxiety (Study 2). In Study 3, another form of defensive pride, narcissism, was associated with exaggerated consensual worldview defense after a system-injustice threat. In Study 4, imagined consensus reduced subjective salience of proud individuals' troubling thoughts. Compensatory consensus is seen as a kind of defensive self-affirmation that defensively proud people turn to for insulation from distressing thoughts.

Adult↗
PubMed1983

A model of the development of the early infant object concept.

A computational model is proposed for the early stages of development of the object concept in infancy. Stages in development are represented as a sequence of grammars or rewrite rules that parse a set of perceptual phenomena. The infant's changes between developmental stages can be described by differences between the grammar rules that model each stage. The program replicates five studies by Bower et al on the development of the object concept and reaffirms the primacy of rest and motion parameters as explanatory invariants in early object-concept development.

Concept Formation↗
PubMed1996

Numerical representations in primates.

Research has demonstrated that human infants and nonhuman primates have a rudimentary numerical system that enables them to count objects or events. More recently, however, studies using a preferential looking paradigm have suggested that preverbal human infants are capable of simple arithmetical operations, such as adding and subtracting a small number of visually presented objects. These findings implicate a relatively sophisticated representational system in the absence of language. To explore the evolutionary origins of this capacity, we present data from an experiment with wild rhesus monkeys (Macaca mulatta) that methodologically mirrors those conducted on human infants. Results suggest that rhesus monkeys detect additive and subtractive changes in the number of objects present in their visual field. Given the methodological and empirical similarities, it appears that nonhuman primates such as rhesus monkeys may also have access to arithmetical representations, although alternative explanations must be considered for both primate species.

Animals↗
PubMed1994

Perceived intellectual performance change over seven years.

Actual and perceived change in intellectual performance over seven years was examined in a sample of 837 participants in the Seattle Longitudinal Study who took five subtests of Thurstone's Primary Mental Abilities (PMA) test in 1977 and 1984. In 1984 participants rated perceived change in intellectual performance from 1977 to 1984. Participants were categorized, based on their actual performance, into those who maintained earlier performance level, significantly increased their performance, or declined in performance. A typology linking actual and perceived change in performance was created: Realists (those who accurately estimated change in their performance); Optimists (those who oveestimated positive change); and Pessimists (those who overestimated negative change). Classification of participants varied across abilities. Women were more likely to be pessimists on Spatial Orientation than men. Older individuals were more likely to be pessimists on Verbal Meaning and Inductive Reasoning Abilities and to be realists on Number ability compared to younger participants.

Adult↗
PubMed2000

Therapeutic drug monitoring of antiretrovirals in human immunodeficiency virus infection.

The era of antiviral therapy directed against HIV-1 has now entered its second decade. In the twelve years since the FDA approved the first antiretroviral drug zidovudine there have been a number of seminal developments that have revolutionized the approach to therapy. These advances converged to change the treatment paradigm from one of therapeutic nihilism to that of cautious optimism. First, several trials demonstrated that combination therapy of nucleoside reverse transcriptase inhibitors (NRTIs) is superior to monotherapy in extending survival and delaying disease progression. Second, the concept of virologic latency in asymptomatic HIV-infected patients was revised. Mathematic modelling demonstrated that there is an ongoing high level of virus production driving a rapid turnover of CD4 cells at all stages of infection. Hence it was concluded that the aim of antiretroviral therapy (ART) should be to "hit early and hit hard." Third, significant advances in molecular virology facilitated the development of quantitative methods to measure the circulating HIV plasma RNA. HIV viral load has been shown to be a sensitive predictor of disease progression and a valuable marker of response to therapy. However, none of these developments would have translated into improved patient care without the advent of two new classes of drugs-the protease inhibitors (PIs) and the nonnucleoside reverse transcriptase inhibitors (NNRTIs).

Anti-HIV Agents↗
PubMed2001

Principle of organization: a dynamic-systems view of the archetype-as-such.

The personality is a dynamic system. Like all other dynamic systems, it must be self-organized. In this paper I focus upon the archetype-as-such, that is, upon the essential core around which both an archetypical image and a complex are organized. I argue that an archetype-as-such is a pre-existing principle of organization. Within the personality that principle manifests itself as a psychological vortex (a complex) into which we are drawn. The vortex is impersonal. We mediate it through myths and rituals or through consciousness. In this paper I show that Jung's intuition about the archetype-as-such is supported by recent science. I evaluate other concepts of the archetype. My concept is different from that proposed recently by Saunders and Skar. My concept allows each archetype-as-such to be defined precisely in mathematical terms. It suggests a new interpretation of mythology. It also addresses our spiritual experience of an archetype. Because the archetypes-as-such are fundamental to the personality, the better we understand them the better we understand our patients. The paper is grounded with clinical examples.

Humans↗