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Results for “Inverse design”

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PubMedDate not supplied

Factors associated with student nurses' intent to provide physical and psychosocial care to persons with acquired immunodeficiency syndrome.

This project examined the influence of selected factors on student nurses' intent to provide physical and psychosocial care to persons hospitalized with acquired immunodeficiency syndrome (AIDS). Respondents were 125 undergraduate upper division nursing majors attending a state-supported university. Questionnaires were distributed to student mailboxes and were returned anonymously through the United States Postal Service. All factors were correlated with intent to provide physical care and with intent to provide psychosocial care using Pearson product-moment correlation coefficients. For both intention scales, attitude toward a person with AIDS acquired through homosexual activity and attitude toward a person with AIDS acquired through sharing needles were positively related to intent to provide care. Homophobia, fear of AIDS, and perceived susceptibility toward acquiring human immunodeficiency virus from providing care were inversely related. These findings are useful for designing programs that promote the delivery of compassionate nursing care to persons with AIDS.

Acquired Immunodeficiency Syndrome↗

PubMed1970

Two radiation-induced chromosomal inversions in mice (Mus musculus).

Whole-body x-irradiation of male mice has produced presumptive paracentric inversions in 15 animals, as evidenced by high frequencies of first meiotic anaphase bridges. Two of the highest frequencies observed have been propagated through several generations and found to behave as dominant genes. Acentric fragments were observed associated with about 10% of the bridges. The first inversion, in linkage group XIII, has been designated In(13)1Rk, and the second, in linkage group XVII, In(17)2Rk. For In(13)1Rk, recombination was reduced between loci inside and outside the inverted segment.

Animals↗

PubMed1993

Increased expression of the insulin-like growth factor I receptor gene, IGF1R, in Wilms tumor is correlated with modulation of IGF1R promoter activity by the WT1 Wilms tumor gene product.

Wilms tumor is a pediatric neoplasm that arises from the metanephric blastema. The expression of the gene encoding insulin-like growth factor II (IGF-II) is often elevated in these tumors. Since many of the actions of IGF-II are mediated through activation of the IGF-I receptor (IGF-IR), we have measured the levels of IGF-IR mRNA in normal kidney and in Wilms tumor samples using solution hybridization/RNase protection assays. IGF-IR mRNA levels in the tumors were 5.8-fold higher than in adjacent normal kidney tissue. Among the tumors themselves, the levels of IGF-IR mRNA in those containing heterologous stromal elements were 2-fold higher (P < 0.01) than in tumors without these elements. IGF-IR gene (designated IGF1R) expression in the tumors was inversely correlated with the expression of the Wilms tumor suppressor gene WT1, whose inactivation appears to be a key step in the etiology of Wilms tumor. Cotransfection of Chinese hamster ovary cells with rat and human IGF-IR gene promoter constructs driving luciferase reporter genes and with WT1 expression vectors showed that the active WT1 gene product represses IGF-IR promoter activity in a dose-dependent manner. These results suggest that underexpression, deletion, or mutation of WT1 may result in increased expression of the IGF-IR, whose activation by IGF-II may be an important aspect of the biology of Wilms tumor.

Animals↗

PubMed2005

Structure-approximating inverse protein folding problem in the 2D HP model.

The inverse protein folding problem is that of designing an amino acid sequence which has a particular native protein fold. This problem arises in drug design where a particular structure is necessary to ensure proper protein-protein interactions. In this paper, we show that in the 2D HP model of Dill it is possible to solve this problem for a broad class of structures. These structures can be used to closely approximate any given structure. One of the most important properties of a good protein (in drug design) is its stability--the aptitude not to fold simultaneously into other structures. We show that for a number of basic structures, our sequences have a unique fold.

Computational Biology↗

PubMed2004

Plasma C-reactive protein and homocysteine concentrations are related to frequent fruit and vegetable intake in Hispanic and non-Hispanic white elders.

Elevated C-reactive protein (CRP) and plasma total homocysteine (Hcy) were recently identified as risk factors for cardiovascular disease. However, few studies have related fruit and vegetable consumption to these markers of inflammation and B vitamin deficiency, particularly in the Hispanic population. We examined the relation of fruit and vegetable intake with plasma CRP and Hcy concentrations in a cross-sectional study. Subjects were 445 Hispanic elders and 154 neighborhood-based non-Hispanic white elders living in Massachusetts. Diet was assessed with a FFQ designed for this population. There were significant inverse dose-response associations between fruit and vegetable intake and plasma CRP (P for trend = 0.010) and Hcy (P for trend = 0.033) concentrations, after adjustment for potential confounders. The prevalence of high plasma CRP (> 10 mg/L), and high Hcy (>10.4 micromol/L for women and >11.4 micromol/L for men), was significantly greater among subjects in the lowest quartile of fruit and vegetable consumption relative to those in the highest quartile, 17.9 vs. 9.1% and 58.7 vs. 44.4%, respectively. With each additional serving of fruit and vegetable intake, adjusted odd ratios for high plasma CRP and Hcy were 0.79 (95% CI: 0.65 to 0.97) and 0.83 (95% CI: 0.72 to 0.96), respectively. Greater frequency of fruit and vegetable intake was associated with significantly lower plasma CRP and Hcy concentrations. Because both of these metabolites are known risk factors for CVD, these findings contribute to the evidence that a higher intake of fruit and vegetables may reduce the risk of CVD.

Aged↗

PubMedDate not supplied

Chromosomal and mitochondrial DNA variation in orang utans.

Wild-born orang utans held in zoos do not have their geographic origins defined, which has complicated comparisons of the two subspecies of orang utans (Bornean orang utans, Pongo pygmaeus pygmaeus, and Sumatran orang utans, P. pygmaeus abelii). The resulting confusion concerning the subspecies identity of individual orang utans and a larger controversy over the desirability of utilizing subspecies designations in orang utan breeding programs has focused attention on the need for a phylogenetic analysis of the species and an examination of the appropriateness of the subspecific designations. Previous studies have suggested that an inversion in the second chromosome pair (PPY2) is a diagnostic subspecies marker and that mitochondrial DNA (mtDNA) and nuclear genetic markers may also be used to identify the subspecies origin of individual orang utans. In an effort to assist zoological parks in examining the question of genetic divergence of orang utan subspecies, we have studied the chromosomes of 144 orang utans, including 58 wild-born individuals. To gain insight into phylogenetic divisions of these apes, mtDNA restriction cleavage site variation has been investigated in 14 individuals whose karyotypic status was known. These investigations have confirmed the existence of two phylogenetic lineages of orang utans based on mtDNA cleavage patterns and demonstrated that these lineages correspond with the two populations characterized by the G-banded morphology of the second pair of chromosomes. The two orang utan phylogenetic units comprise individuals that generally conform to the recognized allopatric, morphological subspecies. Based on current knowledge, the view that the named orangutan subspecies each constitute a distinct phylogenetic lineage more consistent with species-level divergence is supported.

Animals↗

PubMed1991

Measurement of photon-energy albedo from stratified shielding materials.

In the conventional method of measuring photon-energy albedo using a scintillation detector coupled with a multichannel analyzer, tedious efficiency correction by the inverse matrix method was needed. The indigenously designed proportional-response photon counter, with its detection efficiency proportional to energy of incident photons, was used in the present investigation. Use of the proportional-response photon counter makes the measurement straightforward and more accurate. Measurements of energy albedo from stratified layers of aluminum, iron, lead, and concrete using 662-keV and 1250-keV photon energies are reported.

Aluminum↗

PubMed2000

Excitations for lattice ferromagnetic classical spin systems at high temperature: noneven single-spin distributions

We consider general d-dimensional lattice ferromagnetic spin systems with nearest neighbor interactions in the high temperature region (beta<<1). Each model is characterized by a single-site a priori spin probability distribution taken to be noneven. We state our results in terms of the parameter alpha=(<&smacr; (4)>-3<&smacr; (2)>(2)-<&smacr; (3)>(2)<&smacr; (2)>(-1))/(<&smacr; (4)>-<&smacr; (2)>(2)-<&smacr; (3)>(2)<&smacr; (2)>(-1)), where &smacr;=s- , and denotes the kth moment of the single-site distribution. Associated with the model is a lattice quantum field theory which is known to contain a particle of mass m approximately ln beta. Assuming <&smacr;(3)> not equal0 we show that for alpha>0, beta small, there exists a bound state with mass below the two-particle threshold 2m. For alpha<0 bound states do not exist. These results are obtained using a Bethe-Salpeter (BS) equation in the ladder approximation in conjunction with a representation for the inverse of the two-point function designed to analyze the spectrum below but close to 2m.

Journal Article↗

PubMed2000

Exact linearization of the radiation-damped spin system

Nonlinear evolution of the Landau-Lifshitz type can be exactly linearized. Special cases include the radiation-damped spin system and the superradiant system in the semiclassical regime, in the presence of time-varying driving fields. For these, the resultant linear system is simply that of a spin 1 / 2 particle, with the radiation damping rate, or superradiant characteristic time, manifested as an imaginary addition to the spin's resonance frequency. Consequently, methods from inverse scattering theory can be used to design driving fields. The behavior of these systems under stochastic excitation can be determined exactly.

Journal Article↗

PubMed2006

Subspace projection filters for real-time brain electromagnetic imaging.

An increasing number of neuroimaging laboratories are becoming interested in real-time investigations of the human brain. The opportunities offered by real-time applications are inversely proportional to the latency of the brain activity response and to the computational delay of brain activity estimation. Electromagnetic tomographies, based on electroencephalography (EEG) or magnetoencephalography (MEG), feature immediacy of brain activity response and excellent time resolution, hence they are natural candidates. However their spatial resolution and signal-to-noise ratio are poor. In this paper, we develop data-independent and data-dependent subspace projection filters for the standardized low-resolution electromagnetic tomography (sLORETA), a weighted minimum norm inverse solution for EEG/MEG. The filters are designed for extracting time-series of source activity in any given region of interest. The data-independent filter is shown to reduce interference of sources originating in neighboring regions, whereas the data-dependent filter is shown to suppress sensor measurement noise. An effective and straightforward way to combine them is demonstrated. The result is a dual subspace projection allowing both noise suppression and interference reduction.

Brain↗

PubMed2006

Prophylactic ankle bracing reduces rearfoot motion during sudden inversion.

The purpose of this study was to evaluate the effects of ankle bracing on rearfoot angular displacement and angular velocity during a sudden inversion movement. A 1 x 3 factorial design was used. The single independent variable was ankle brace condition with three levels: semi-rigid, lace-up and control. The two dependent variables were rearfoot average angular displacement and average angular velocity. Twenty-four healthy volunteers participated in this study. A motion analysis system was used to capture, model and calculate two-dimensional rearfoot motion while the subjects' ankle/foot complex was inverted to 35 degrees on a platform device. All subjects performed five trials of each ankle brace condition, and the average of these trials was used for statistical analysis. The semi-rigid brace significantly reduced rearfoot angular displacement and angular velocity compared with the lace-up (P<0.05) and control conditions (P<0.05). Additionally, the lace-up style brace demonstrated significantly less rearfoot angular displacement and angular velocity compared with the control condition (P<0.05). These results demonstrate that a semi-rigid ankle brace is more superior then a lace-up style brace in limiting rearfoot angular displacement and angular velocity. Moreover, the lace-up style brace offers significant restriction of these measures compared with no support.

Adult↗

PubMedDate not supplied

A photoacoustical radiation dosimeter.

A new type of radiation dosimeter using the photoacoustical effect is described. The photoacoustical radiation dosimeter (PARD) is capable of directly measuring the energy absorbed in the detecting element. For a completely absorbing element, the energy fluence rate in the radiation beam is measured. It is thus a calorimetric dosimeter. Since the energy sensor can be calibrated with another form of energy, it has the potential for being an absolute radiation dosemeter. Measurements were made using 50 to 100 kVp x rays with exposure rates at the detector of 2.6 x 10(-6) C/kg/s (10 mR/s) to 5 x 10(-5) C/kg/s (200 mR/s). The minimum measurable exposure rate at 90 kVp is 5 x 10(-7) C/kg/s (2 mR/s). For a given x-ray spectrum, the PARD has a linear response with radiation intensity and an inverse response with chopping frequency. With appropriate design parameters, we believe the PARD may be used to measure any photon energy or any type of radiation particle.

Acoustics↗

PubMed1999

Theoretical considerations of monitor unit calculations for intensity modulated beam treatment planning.

A treatment planning system to compute intensity modulated radiotherapy (IMRT) treatments using inverse planning was investigated. The system was designed to optimize the intensity patterns required to treat a specified target volume with specified normal structure constraints. A beam model that uses the convolution of pencil beams was used to compute the dose distributions. A multileaf collimator leaf-setting sequence intended to produce the intensity pattern was computed along with the monitor units required to deliver each of a number of fixed-gantry modulated fields. Computer calculations are commonly verified using an independent manual procedure. It is difficult to calculate treatment delivery monitor units for this variant of IMRT using manual methods. Since manual calculations are not feasible, it is important both to understand and to verify the calculation of treatment monitor units by the planning system algorithm. A formal analysis was made of the dose calculation model and the monitor unit calculation embedded in the algorithm. Experimental verification of the dose delivered by plans computed with the methodology demonstrated an agreement of better than 4% between the dose model and measurements.

Algorithms↗

PubMed1997

PHR2 of Candida albicans encodes a functional homolog of the pH-regulated gene PHR1 with an inverted pattern of pH-dependent expression.

Deletion of PHR1, a pH-regulated gene of Candida albicans, results in pH-conditional defects in growth, morphogenesis, and virulence evident at neutral to alkaline pH but absent at acidic pH. Consequently, we searched for a functional homolog of PHR1 active at low pH. This resulted in the isolation of a second pH-regulated gene, designated PHR2. The expression of PHR2 was inversely related to that of PHR1, being repressed at pH values above 6 and progressively induced at more acidic pH values. The predicted amino acid sequence of the PHR2 protein, Phr2p, was 54% identical to that of Phr1p. A PHR2 null mutant exhibited pH-conditional defects in growth and morphogenesis analogous to those of PHR1 mutants but manifest at acid rather than alkaline pH values. Engineered expression of PHR1 at acid pH in a PHR2 mutant strain and PHR2 at alkaline pH in a PHR1 mutant strain complemented the defects in the opposing mutant. Deletion of both PHR1 and PHR2 resulted in a strain with pH-independent, constitutive growth and morphological defects. These results indicate that PHR1 and PHR2 represent a novel pH-balanced system of functional homologs required for C. albicans to adapt to environments of diverse pH.

Amino Acid Sequence↗

PubMed2004

Detection of apical hypertrophic cardiomyopathy by cardiovascular magnetic resonance in patients with non-diagnostic echocardiography.

OBJECTIVE: To investigate the role of cardiovascular magnetic resonance (CMR) in a series of patients with ECG repolarisation changes and normal echocardiography. PATIENTS AND DESIGN: 10 patients with anterolateral T wave inversion for which there was no obvious pathological cause who had normal routine echocardiography without contrast for the exclusion of hypertrophic cardiomyopathy (HCM) also had CMR that was diagnostic of apical HCM. RESULTS: Apical HCM detected by CMR could be morphologically severe with wall thickness up to 28 mm, or mild. The extent of repolarisation abnormalities did not correlate to the morphological severity. CONCLUSIONS: In patients with unexplained repolarisation abnormalities, a normal routine echocardiogram without contrast does not exclude apical HCM. Further imaging with CMR or contrast echocardiography may be required. The reliance on routine echocardiography to exclude apical HCM may have led to underreporting of this condition.

Cardiomyopathy, Hypertrophic↗

PubMed1993

Learned helplessness as an interacting variable with self-care agency: testing a theoretical model.

This article describes the theoretical development and initial testing of a model outlining the interaction of the concepts of self-care agency and learned helplessness in healthy working adults. Orem's theory of self-care and the reformulated learned helplessness theory are discussed as the theoretical basis for the study. The self-care agency conditioning factors, age and gender, were examined for relationships to the main variables. In a descriptive, correlational design, the hypothesis, that learned helplessness was inversely related to self-care agency, was supported (r = -.57). Neither age nor gender was related to main variables in the population. Implications for nursing research, self-care theory clarification, and nursing practice are discussed.

Adult↗

PubMed1981

Studies in MBO effectiveness.

Management by objectives (MBO) is a popular management approach the efficacy of which has been seriously questioned recently. I have analyzed 185 studies for the effects of MBO on employee productivity and/or job satisfaction. Research support for MBO was found to be inversely related to the degree of research design sophistication. Although the five well-controlled experiments leaned toward finding MBO to be ineffective, it appears a contingency approach to MBO is more appropriate than a definitive affirmation or rejection of MBO effectiveness.

Evaluation Studies as Topic↗

PubMed2004

Inverse protein folding in 2D HP mode (extended abstract).

The inverse protein folding problem is that of designing an amino acid sequence which has a particular native protein fold. This problem arises in drug design where a particular structure is necessary to ensure proper protein-protein interactions. In this paper we show that in the 2D HP model of Dill it is possible to solve this problem for a broad class of structures. These structures can be used to closely approximate any given structure. One of the most important properties of a good protein is its stability -- the aptitude not to fold simultanously into other structures. We show that for a number of basic structures, our sequences have a unique fold.

Algorithms↗