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We demonstrate a novel frequency-resolved optical gating (FROG) configuration based on cascaded second-order nonlinear interactions. Its implementation in a 2.6 cm long quasi-phase-matched LiNbO3 waveguide allowed high-quality retrieval of 2 ps to 80 fJ pulses at 1.56 microm.
The beta-fibrinogen G/A-455 polymorphism genotype along with plasma fibrinogen levels was determined in 482 healthy middle-aged men, of whom 231 were smokers. Smokers had the highest plasma fibrinogen levels (2.92 g/l), ex-smokers the next (2.73 g/l), and never-smokers the lowest levels (2.66 g/l, P < 0.001). Those with one or two A-455 alleles had significantly higher plasma fibrinogen levels in never-smokers and ex-smokers (8.2% and 9.0%, respectively, P < 0.05), and the effect was larger in younger men (45 < 55 years, 11.6%, P = 0.002) than older men (> 65 years, 4.5%, NS), and was not significant in smokers (2.4%, P > 0.05). Allele frequencies were calculated and compared across age groups and between smokers and non-smokers. The difference in frequency of the A-455 allele between smokers and non-smokers varied significantly with age (P < 0.01), with the frequency of the A-455 allele being significantly lower in smokers than in non-smokers in subjects aged > 65 years (P < 0.05), but not in younger men. This demonstrates an interaction between age, smoking and allele frequency of the G/A-455 polymorphism in this population-based sample.
Interactions of acoustic cavitation bubbles with biological tissues play an important role in biomedical applications of ultrasound. Acoustic cavitation plays a particularly important role in enhancing transdermal transport of macromolecules, thereby offering a noninvasive mode of drug delivery (sonophoresis). Ultrasound-enhanced transdermal transport is mediated by inertial cavitation, where collapses of cavitation bubbles microscopically disrupt the lipid bilayers of the stratum corneum. In this study, we describe a theoretical analysis of the interactions of cavitation bubbles with the stratum corneum lipid bilayers. Three modes of bubble-stratum corneum interactions including shock wave emission, microjet penetration into the stratum corneum, and impact of microjet on the stratum corneum are considered. By relating the mechanical effects of these events on the stratum corneum structure, the relationship between the number of cavitation events and collapse pressures with experimentally measured increase in skin permeability was established. Theoretical predictions were compared to experimentally measured parameters of cavitation events.
This investigation explored 2 hypotheses derived from socioemotional selectivity theory: (a) Selective reductions in social interaction begin in early adulthood and (b) emotional closeness to significant others increases rather than decreases in adulthood even when rate reductions occur. Transcribed interviews with 28 women and 22 men from the Child Guidance Study, conducted over 34 years, were reviewed and rated for frequency of interaction, satisfaction with the relationship, and degree of emotional closeness in 6 types of relationships. Interaction frequency with acquaintances and close friends declined from early adulthood on. Interaction frequency with spouses and siblings increased across the same time period and emotional closeness increased throughout adulthood in relationships with relatives and close friends. Findings suggest that individuals begin narrowing their range of social partners long before old age.
In the mustached bat's central nucleus of the inferior colliculus (ICC), many neurons display facilitatory or inhibitory responses when presented with two tones of distinctly different frequencies. Our previous studies have focused on spectral interactions between specific frequency bands contained in the bat's sonar vocalization. In this study, we describe excitatory and facilitatory frequency response areas across all frequencies in the mustached bat's audible range. We show that many neurons in the ICC have more extensive frequency interactions than previously documented. We recorded responses of 96 single units to single tones and combinations of two tones. Best frequencies of the units ranged from 59-15 kHz. Forty-one units had a single, excitatory frequency response area. The rest of the units had more complex frequency tuning that included multiple excitatory frequency response areas and facilitatory frequency response areas. Some of the facilitatory frequency interactions were between one sound with energy in a sonar frequency band and a second sound with energy in a non-sonar frequency band. We also found that neurons could be facilitated by more than one additional frequency band. Our findings of extensive frequency interactions in the ICC of the mustached bat suggest that some neurons may be well suited for the analysis of complex sounds, possibly including social communication sounds.
Two sets of experiments were carried out to examine dependencies of two types of induced motion (motion assimilation and motion contrast) on spatial properties of stimuli in terms of spatial-frequency tuning of local motion detectors. In the first set, the magnitudes of motion assimilation and motion contrast for a sinusoidal grating were measured at a function of the spatial frequency of the inducing gratings, with the spatial frequency of the test grating as a parameter. In the second set, the magnitudes were measured as a function of the height of the inducing gratings with the spatial frequencies of the test and the inducing gratings as parameters. For motion assimilation, the magnitude was characterized by a low-pass function of the spatial frequency of the inducing gratings, and the critical height of the inducing gratings, which demarcates the extent of the spatial pooling, varied systematically depending on the spatial frequency of the inducing gratings. For motion contrast, on the other hand, the magnitude was characterized by a hand-pass function, and the critical height depended on the frequency of the test grating. These results suggest that motion assimilation is mediated by the spatial-frequency nonselective interaction between the local detectors, in which the motion signals of the detectors tuned to different spatial frequencies are integrated with each other. Motion contrast is mediated by the spatial-frequency selective interaction, in which the motion signals of the local detectors tuned to the same or similar spatial frequencies are compared and differentiated.
OBJECTIVES: To address the questions of whether women should be included in bioequivalence trials and whether dosage adjustment may be needed in women relative to men. METHODS: Sex-related analysis was conducted for 26 bioequivalence studies involving both sexes. A total of 94 data sets [47 each for the areas under the plasma concentration-time curve (AUC) and maximum concentration (Cmax)] were used. ANOVA was performed. Three statistical models were used to estimate population means and intrasubject variability between sexes, as well as sex-by-formulation interactions. Comparisons were made by use of confidence intervals, magnitude of observed differences, and statistical significance (alpha = .05). RESULTS: With some exceptions, intrasubject variabilities were similar for men and women. In about 10% of the data sets (AUC or Cmax), women had significantly higher variability. Although fewer, there were examples with higher variability in men. With a 20 percentage point difference used in the test-over-reference mean ratios between sexes as a signal of sex-by-formulation interaction, the frequency of this interaction (AUC or Cmax) is approximately 13% and approximately 35%, counting by data sets and studies, respectively. Mean sex-related differences of > or = 20% in the pharmacokinetic parameters for the reference product were observed in 39% of the data sets (AUC or Cmax). In approximately 28% of the data sets, these differences were statistically significant. The frequency was approximately 15% after body weight correction. CONCLUSIONS: In general, men and women have similar intrasubject variability. Where variability differs between sexes, there is a suggestion that higher variability in women may be more frequent. The data also suggest that a sex-based subject-by-formulation interaction can occur, although the frequency may be low. Sex-related differences in pharmacokinetics are apparent in many drugs studied. Dosage adjustment with body weight may be warranted for drugs that exhibit a steep dose-response curve. Although exploratory, the results of this study support recommendations of the 1993 Food and Drug Administration gender guideline that women not be excluded from bioequivalence trials.
Common complex polygenic diseases as autoimmune diseases have not been completely understood on a molecular level. While many genes are known to be involved in the pathways responsible for the phenotype, explicit causes for the susceptibility of the disease remain to be elucidated. The susceptibility to disease is thought to be the result of genetic epistatic interactions between common polymorphic genes. This polymorphism is mostly caused by single nucleotide polymorphisms (SNPs). Human subpopulations are known to differ in the susceptibility to the diseases and generally in the distribution of single nucleotide polymorphisms. The here presented approach retrieves SNPs with the most divergent frequencies for selected human subpopulations to help defining properties for the experimental verification of SNPs within defined regions. A web-accessible program implementing this approach was evaluated for multiple sclerosis (MS), a common human polygenic disease. A link to a summary of data from "The SNP Consortium" (TSC) with sex-dependencies of SNPs is available. Associations of SNPs to genes, genetic markers and chromosomal loci are retrieved from the Ensembl project. This tool is recommended to be used in conjunction with microarray analyses or marker association studies that link genes or chromosomal loci to particular diseases.
During the last decade, use of radio frequency (RF) applications like mobile phones and other wireless devices, has increased remarkably. This has triggered numerous studies related to possible health risks due to the exposure of RF electromagnetic (EM) fields. One safety aspect is the coupling of EM fields with active and passive implants in the human body. While interactions with active implants have been quite extensively researched, only a few studies have focused on passive implants. The present article reviews interaction mechanisms and studies of passive metallic, that is, conductive, implants in common external RF EM fields. It is found that implants have been mostly studied numerically, and experimental studies are rare. Furthermore, the studies cover mostly far-field conditions and only a few have studied implants in near fields. A summary of results indicates that a conductive object in tissues may cause notable local enhancement of the EM field and thus enhanced power absorption. The degree of enhancement depends, for example, on the orientation, the dimensions, the shape, and the location of the implant. However, in most of the cases, the field enhancement has not been strong enough to cause remarkable excess heating (more than 1 degrees C) of tissues.
OBJECTIVE: To determine the role of polymorphisms in the genes for beta3-adrenergic receptor (beta3-AR) and in uncoupling proteins 1 and 2 (UCP-1, UCP-2) in obesity. DESIGN: Association study with three polymorphisms and obesity. SUBJECTS: Two hundred and thirty-six morbidly obese patients who underwent gastric banding surgery, 381 patients from the medical clinic and 198 healthy blood donors. MEASUREMENTS: The frequencies of the W64R in beta3-AR, the 3826A-->G in UCP-1 and the 45bp insertion in the 3 untranslated region of exon 8 in UCP-2 polymorphisms were determined. RESULTS: There were no significant differences in the frequencies of the beta3-AR and UCP-1 polymorphisms between obese (body mass index, BMI > 30 kg/m2) and lean subjects. Lean, but not obese, carriers of the R allele of beta3-AR had a significantly higher BMI. The mean age of obese subjects (excluding diabetics) who were carriers of the G allele of the UCP-1 polymorphism, 36y, was significantly younger than wild-type, 40y (P= 0.007). This effect was not seen in lean subjects. The effect of the G allele on the mean age of obese subjects was more apparent in subjects who were also carriers of the R allele of the beta3-AR polymorphism. The frequency of the ins allele of UCP-2 was significantly higher in obese subjects, 0.31, than in lean, 0.24 (P= 0.002) and carriers of the ins allele had a significantly higher BMI, 38 vs 35 (P= 0.005). There was no association between any of the polymorphisms and type II diabetes. CONCLUSION: In a German population, there was no association between the W64R in beta3-AR or the 3826A-->G in UCP-1 polymorphisms and obesity. However, they act synergistically to accelerate the development of obesity. The 45bp insertion in the 3 untranslated region of exon 8 in UCP-2 polymorphism is associated with obesity.
Six pigeons were trained on concurrent variable-interval schedules with unequal reinforcer durations for the two responses. The schedules arranged on the two keys were kept equal while they were varied in absolute size. As the overall reinforcer rate was increased, both response-allocation and time-allocation measures of choice showed a trend toward indifference, and measures of sensitivity to reinforcer-duration ratios significantly decreased. Recent reports have shown that the generalized matching law cannot describe the changes in behavior allocation under constant delay-, duration-, or rate-ratios when changes are made in the absolute levels of each of these variables. The present results complement these findings by demonstrating that the concatenated generalized matching law cannot describe the interactions of two reinforcer variables on behavior allocation.
We examined how vernier thresholds for flickering bars depend on the temporal frequency and relative temporal phase of the bars. The largest effect of relative phase (up to a fivefold increase in displacement thresholds) was seen at 2 Hz, and for most subjects, relative phase had little effect at 16 Hz and above. The effect of relative phase was essentially independent of contrast and trial duration. Thresholds were elevated by the greatest amount when bars were presented in antiphase, but at 1 and 4 Hz, quadrature phase offsets also led to substantial elevations in displacement thresholds. An experiment designed to examine the interaction of the vernier judgment with apparent motion failed to identify a role for mechanisms sensitive to apparent motion in threshold elevation. Another experiment in which the bars were modulated with sawtooth waveforms indicated that temporal correlation between the bars, rather than the ON versus OFF distinction, underlies the phase sensitivity. A simple dynamical model that posits partial rectification prior to a cross-correlation-like interaction accounts for the observed results.
This study investigates the influence of fundamental frequency (F0) contour on perceived vowel duration in Norwegian. In the first of four experiments, a falling vs. flat contour in short vs. long vowels in isolated monosyllables was shown to cause a perceptual lengthening of the vowel. Contrary to the expectations, embedding the monosyllables sentence-medially in experiment 2 did not turn the lengthening into a shortening effect. Also unexpectedly, a rising vs. flat contour did not influence perceived duration in monosyllables (experiment 3). Experiment 4 focused on falling as well as rising contours in disyllabic test words. Here, too, a lengthening effect was found only for a falling pattern. In parallel with experiment 2, the presence of the test word's second syllable did not turn perceptual lengthening into perceptual shortening. Comparison of the present results with data previously reported for German leads to the conclusion that the interaction of F0 contour and perceived vowel duration is language-specific and cannot be explained by assuming a universal psychophysical mechanism.
The interaction of the effects of luminance and spatial frequency on perception of suprathreshold contrast was studied with use of a contrast-matching paradigm. Four subjects matched the appearance of Gabor patches at different luminances and spatial frequencies. The contrast of a 1-octave Gabor test patch at one of five frequencies [1-16 cycles/degree (c/deg) in 1-octave steps] and at one of seven mean luminance levels (0.5-50 cd/m2 in 1/3-log-unit steps) was matched, by the method of adjustment to a standard patch of 3 c/deg at 50 cd/m2 at a nominal contrast of 0.3. For each block of trials the spatial frequency of the test patch was randomly changed (three repetitions at each frequency per block) while the luminance was fixed. The subject regularly shifted fixation between the two targets in response to a metronome tone every 1.5 s. Contrast constancy was demonstrated across the entire luminance range tested for all but the two highest frequencies. For 8 c/deg the perceived test contrast was reduced only when the luminance was less than 2 cd/m2. For 16 c/deg, perceived contrast decreased linearly (with a slope of -1/2 on a log scale) with decreases in luminance across the entire luminance range. As at threshold, reduction in luminance across the levels commonly available on a CRT display has only minimal effects on low-frequency suprathreshold contrast perception. However, the apparent contrast of high-frequency features, in binocular free-viewing conditions, is rapidly reduced with a local reduction in screen luminance. This effect has important implications for visual models used in image-quality analysis.
We investigate host-pathogen dynamics and conditions for coexistence in two models incorporating frequency-dependent horizontal transmission in conjunction with vertical transmission. The first model combines frequency-dependent and uniparental vertical transmission, while the second addresses parasites transmitted vertically via both parents. For the first model, we ask how the addition of vertical transmission changes the coexistence criteria for parasites transmitted by a frequency-dependent horizontal route, and show that vertical transmission significantly broadens the conditions for parasite invasion. Host-parasite coexistence is further affected by the form of density-dependent host regulation. Numerical analyses demonstrate that within a host population, a parasite strain with horizontal frequency-dependent transmission can be driven to extinction by a parasite strain that is additionally transmitted vertically for a wide range of parameters. Although models of asexual host populations predict that vertical transmission alone cannot maintain a parasite over time, analysis of our second model shows that vertical transmission via both male and female parents can maintain a parasite at a stable equilibrium. These results correspond with the frequent co-occurrence of vertical with sexual transmission in nature and suggest that these transmission modes can lead to host-pathogen coexistence for a wide range of systems involving hosts with high reproductive rates.
UNLABELLED: We describe unexpected episodes of paced tachycardia in two patients with rate-responsive pacemakers during anaesthesia. Five months after a heart transplant and implantation of a pacemaker a 43-year-old patient suffered cardiac tamponade as a result of chronic pericarditis. The second case involved embolic occlusion of the femoral artery in a 33-year-old female patient previously operated on for tricuspid valve replacement and implantation of a pacemaker. In both cases induction of anaesthesia was performed with fentanyl, etomidate and vecuronium. Following intubation and mechanical ventilation, the heart rates (HR) of the two patients increased to 140 and 130 min-1 respectively. This was interpreted as a sign of inadequate anaesthesia, and therefore additional doses of fentanyl and etomidate were given, with no effect on the tachycardia. After exclusion of other possible reasons for this complication such as hypokalaemia, hypercapnia, hypoxaemia or allergic reactions, unexpected functioning of the rate-responsive pacemakers due to thoracic impedance changes was assumed. Minute ventilation was reduced, lowering paced HR in 3-5 min. CONCLUSIONS: These case reports suggest that anaesthetic management affects the action of rate-responsive pacemakers, causing haemodynamic complications, and inadequate interventions by the anaesthesiologist. Thus, it is necessary for anaesthesiologists to make a preoperative evaluation of the underlying medical disease and the type of pacemaker in order to adjust anaesthetic management accordingly and to understand the haemodynamic responses that may occur during the perioperative period. Preoperative programming to exclude the rate-responsive function is advised.
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