The impact of myocardial infarction on basal and stress-induced heart rate variability and cortisol secretion in women: A pilot study.

Coronary heart disease (CHD), of which myocardial infarction (MI) is a subtype, is the leading cause of death for women. Nonetheless, women remain neglected in CHD research, resulting in treatments and recommendations being primarily based on data collected in men. Pre-clinical and clinical studies have supported dysregulation of the hypothalamic-pituitary-adrenal axis (HPAA) following cardiac arrest and MI to promote the development of mental health disorders (e.g., major depressive disorder, post-traumatic stress disorder). However, studies addressing changes in HPAA activation under basal and stress-induced conditions in women samples have been lacking. Thus, we conducted this study to determine basal and stress-induced changes in heart rate, respiration and cortisol secretion (via 8 saliva samples) in a sample of women with a history of MI (n = 13) and a control group (n = 16). We measured altered stress reactivity through exposure to the Trier Social Stress Test. In addition, participants completed questionnaires assessing perceived stress and mental health status (i.e., anxiety and mood). Overall, our findings indicated comparable assessments of perceived situational stress in both groups. Interestingly, salivary cortisol secretion support reduced stress-induced HPAA activation related to TSST exposure in MI women compared to control counterparts. Our observations are consistent with findings supporting glucocorticoid resistance noted following MI and cardiac arrest. Akin to cardiac arrest survivors, HPAA dysregulation in MI survivors could have an impact on the development of mental health disorders. More studies are needed to address this critical question.

Distortion optimization for wide-angle computational cameras.

An imaging system design procedure for miniature wide-angle computational cameras with subsequent software correction of distortion is described. Such miniature wide-angle computational cameras have a broad range of applications, including eye-tracked extraocular cameras for retinal prostheses, and also wearable visual aids for the blind and those with low vision. As significant (typically barrel) distortion is commonplace in wide-field-of-view imaging systems, digital post-processing is often employed to generate rectilinear output images. Relaxation of the constraint on distortion during the optical system design process is shown to allow for improved optimization of other image-degrading aberrations. Analysis of the effects of distortion on the software-corrected final image during optical design is accomplished by using comprehensive image quality metrics such as the correlation coefficient and the spatial frequency response. Selection of a surprisingly large exact initial distortion value as a constraint allows for the design of a miniature wide-angle imaging system that yields significantly enhanced final image quality.

17beta-Estradiol potentiates field excitatory postsynaptic potentials within each subfield of the hippocampus with greatest potentiation of the associational/commissural afferents of CA3.

We sought to determine the impact of 17beta-estradiol throughout the hippocampal trisynaptic pathway and to investigate the afferent fiber systems within CA1 and CA3 in detail. To achieve this objective, we utilized multielectrode arrays to simultaneously record the field excitatory postsynaptic potentials from the CA1, dentate gyrus, and CA3 of rat hippocampal slices in the presence or absence of 100 pM 17beta-estradiol. We confirmed our earlier findings in CA1, where 17beta-estradiol significantly increased field excitatory postsynaptic potentials amplitude (20%+/-3%) and slope (22%+/-7%). 17beta-Estradiol significantly potentiated the field excitatory postsynaptic potentials in dentate gyrus, amplitude (15%+/-4%) and slope (17%+/-5), and in CA3, amplitude (15%+/-4%) and slope (19%+/-5%). Using a high-density multielectrode array, we sought to determine the source of potentiation in CA1 and CA3 by determining the impact of 17beta-estradiol on the apical afferents and the basal afferents within CA1 and on the mossy fibers and the associational/commissural fibers within CA3. In CA1, 17beta-estradiol induced a modest increase in the amplitude (7%+/-2%) and slope (9%+/-3%) following apical stimulation with similar magnitude of increase following basal stimulation amplitude (10%+/-2%) and slope (12%+/-3%). In CA3, 17beta-estradiol augmented the mossy fiber amplitude (15%+/-3%) and slope (18%+/-6%) and the associational/commissural fiber amplitude (31%+/-13%) and slope (40%+/-15%). These results indicate that 17beta-estradiol potentiated synaptic transmission in each subfield of the hippocampal slice, with the greatest magnitude of potentiation at the associational/commissural fibers in CA3. 17beta-Estradiol regulation of CA3 responses provides a novel site of 17beta-estradiol action that corresponds to the density of estrogen receptors within the hippocampus. The implications of 17beta-estradiol potentiation of the field potential in each of the hippocampal subfields and in particular CA3 associational/commissural fibers for memory function and clinical assessment are discussed.

Convergence of backward-error-propagation learning in photorefractive crystals.

We analytically determine that the backward-error-propagation learning algorithm has a well-defined region of convergence in neural learning-parameter space for two classes of photorefractive-based optical neural-network architectures. The first class uses electric-field amplitude encoding of signals and weights in a fully coherent system, whereas the second class uses intensity encoding of signals and weights in an incoherent/coherent system. Under typical assumptions on the grating formation in photorefractive materials used in adaptive optical interconnections, we compute weight updates for both classes of architectures. Using these weight updates, we derive a set of conditions that are sufficient for such a network to operate within the region of convergence. The results are verified empirically by simulations of the xor sample problem. The computed weight updates for both classes of architectures contain two neural learning parameters: a learning-rate coefficient and a weight-decay coefficient. We show that these learning parameters are directly related to two important design parameters: system gain and exposure energy. The system gain determines the ratio of the learning-rate parameter to decay-rate parameter, and the exposure energy determines the size of the decay-rate parameter. We conclude that convergence is guaranteed (assuming no spurious local minima in the error function) by using a sufficiently high gain and a sufficiently low exposure energy per weight update.

Analysis of weighted fan-out/fan-in volume holographic optical interconnections.

The feasibility of employing volume holographic techniques for the implementation of highly multiplexed weighted fan-out/fan-in interconnections is analyzed on the basis of interconnection fidelity, optical throughput, and complexity of recording schedule or implementation hardware. These feasibility criteria were quantitatively evaluated using the optical beam propagation method to numerically simulate the diffraction characteristics of volume holographic interconnections recorded in a linear holographic material. We find that conventional interconnection architectures (that are based on a single coherent optical source) exhibit a direct trade-off between interconnection fidelity and optical throughput on the one hand, and recording schedule or hardware complexity on the other. In order to circumvent this trade-off we describe and analyze in detail an incoherent/coherent double angularly multiplexed interconnection architecture that is based on the use of multiple-source array of individually coherent but mutually incoherent sources. This architecture either minimizes or avoids several key sources of cross talk, permits simultaneous recording of interconnection weights or weight updates, and provides enhanced fidelity, interchannel isolation, and thróughput performance.

Single-step copying process for multiplexed volume holograms.

A technique for copying the index or absorption modulation of a multiplexed volume holographic element into a second volume holographic medium is presented. The technique utilizes a set of coherent but mutually incoherent optical sources and can perform the copy process in a single exposure step. The concept is demonstrated experimentally for the case of three angularly multiplexed holographic gratings in dichromated gelatin.

Photopolymer-based stratified volume holographic optical elements.

We report the implementation of stratified volume holographic optical elements (SVHOE's) using DuPont's Omnidex holographic photopolymer material and an in situ exposure technique for simultaneous multilayer grating recording. Experimental measurement of the +1-order angular sensitivity of a seven-layer SVHOE structure shows remarkable agreement with both theory and numerical simulation for incidence angles near the Bragg angle. For SVHOE's having modulation layers that individually operate in the Bragg or transition diffraction regimes, the envelope of the SVHOE angular sensitivity is experimentally shown to approximate closely that of a single modulation layer.

On the evolution of Tn21-like multiresistance transposons: sequence analysis of the gene (aacC1) for gentamicin acetyltransferase-3-I(AAC(3)-I), another member of the Tn21-based expression cassette.

The aminoglycoside-3-O-acetyltransferase-I gene (aacC1) from R plasmids of two incompatibility groups (R1033 [Tn1696], and R135) was cloned and sequenced. In the case of R1033, it was shown that the aacC gene is coded by a precise insertion of 833 bp between the aadA promoter and its structural gene in a Tn21 related transposon (Tn1696). This insertion occurs at the same target sequence as that of the OXA-1 beta-lactamase gene insertion in Tn2603. Upstream of the aacC gene, we found an open reading frame (ORF) which is probably implicated in the site-specific recombinational events involved in the evolution of this family of genetic elements. These results provide additional confirmation of the role of Tn21 elements as naturally occurring interspecific transposition and expression cassettes.

Stratified volume holographic optical elements.

A computational algorithm for analyzing diffraction properties of optical devices, the optical beam propagation method, has suggested a new class of devices by which Bragg regime (thick grating) response can be obtained from a spaced sequence of thin grating layers. Such stratified volume holographic optical elements (SVHOE's) can emulate distributed volume gratings in terms of diffraction efficiency and angular selectivity and in addition possess periodic diffraction properties that might serve, for example, as interconnections for optical cellular logic arrays. SVHOE's also offer a unique capability for altering the device diffraction response on a layer-by-layer basis, allowing for control of both the diffraction peak width and the angular separation of adjacent peaks.

Polarization properties of the variable-grating-mode liquid-crystal device.

The principal features of the liquid-crystal molecular orientation within the variable-grating-mode liquid-crystal device have been determined as a function of the applied voltage across the cell by measurement of the polarization properties of light diffracted by the liquid-crystal birefringent phase grating.

Effects of operating mode on electrooptic spatial light modulator resolution and sensitivity.

The strikingly opposite dependences of PROM and PRIZ electrooptic spatial light modulator resolution and sensitivity on operating mode have been modeled by including the effects of bulk charge distributions on the longitudinal and transverse fields. It is shown that the relative performance of PROM and PRIZ devices is strongly influenced by the choice of operating mode and by the quality of the dielectric blocking layers.

Improved method of assay for choline.

A modified assay for choline is described which is shorter, yields more consistent responses, and requires considerably less time, space, and equipment than the existing assays.

Survival of Saccharomyces cerevisiae and Sarcina lutea at Refrigerator Temperatures.

Assay organisms Saccharomyces cerevisiae and Sarcina lutea, when suspended in a weak buffer and stored at refrigerator temperatures, are stable for 1 year or more.

Improvement of the microbiological assay for calcium leucovorin.

The calcium leucovorin assay was improved by adding THORAL germicide which resuspended the cells so that an accurate turbidity reading could be obtained.