Visual Projection Neurons Mediating Directed Courtship in Drosophila.

Many animals rely on vision to detect, locate, and track moving objects. In Drosophila courtship, males primarily use visual cues to orient toward and follow females and to select the ipsilateral wing for courtship song. Here, we show that the LC10 visual projection neurons convey essential visual information during courtship. Males with LC10 neurons silenced are unable to orient toward or maintain proximity to the female and do not predominantly use the ipsilateral wing when singing. LC10 neurons preferentially respond to small moving objects using an antagonistic motion-based center-surround mechanism. Unilateral activation of LC10 neurons recapitulates the orienting and ipsilateral wing extension normally elicited by females, and the potency with which LC10 induces wing extension is enhanced in a state of courtship arousal controlled by male-specific P1 neurons. These data suggest that LC10 is a major pathway relaying visual input to the courtship circuits in the male brain.

Strategies for enhancing automatic fixation detection in head-mounted eye tracking.

Moving through a dynamic world, humans need to intermittently stabilize gaze targets on their retina to process visual information. Overt attention being thus split into discrete intervals, the automatic detection of such fixation events is paramount to downstream analysis in many eye-tracking studies. Standard algorithms tackle this challenge in the limiting case of little to no head motion. In this static scenario, which is approximately realized for most remote eye-tracking systems, it amounts to detecting periods of relative eye stillness. In contrast, head-mounted eye trackers allow for experiments with subjects moving naturally in everyday environments. Detecting fixations in these dynamic scenarios is more challenging, since gaze-stabilizing eye movements need to be reliably distinguished from non-fixational gaze shifts. Here, we propose several strategies for enhancing existing algorithms developed for fixation detection in the static case to allow for robust fixation detection in dynamic real-world scenarios recorded with head-mounted eye trackers. Specifically, we consider (i) an optic-flow-based compensation stage explicitly accounting for stabilizing eye movements during head motion, (ii) an adaptive adjustment of algorithm sensitivity according to head-motion intensity, and (iii) a coherent tuning of all algorithm parameters. Introducing a new hand-labeled dataset, recorded with the Pupil Invisible glasses by Pupil Labs, we investigate their individual contributions. The dataset comprises both static and dynamic scenarios and is made publicly available. We show that a combination of all proposed strategies improves standard thresholding algorithms and outperforms previous approaches to fixation detection in head-mounted eye tracking.

Regional mudstone compaction trends in the Vienna Basin: top seal assessment and implications for uplift history.

Seal quality assessment is not only essential in petroleum systems studies but also in the context of other geo energy applications such as underground hydrogen storage. Capillary breakthrough pressure controls top seal capacity in the absence of faults or other discontinuities. In basins that lack measured capillary pressure data (e.g., from drill cores), regional compaction-porosity trends can be used as a first prediction tool to estimate the capillary properties of mudstones. Mathematical compaction models exist but need to be calibrated for each basin. This study aims to establish a compaction trend based on theoretical models, then compare it with theoretical maximum hydrocarbon column heights inferred from true measured capillary pressure curves. Middle to upper Miocene mudstone core samples from the Vienna Basin, covering a broad depth interval from 700 to 3400 m, were investigated by X-ray diffractometry, with an Eltra C/S analyzer, and by Rock-Eval pyrolysis for bulk mineralogy, total organic carbon, and free hydrocarbon contents. Broad ion beam-scanning electron microscopy, mercury intrusion capillary porosimetry, and helium pycnometry were applied to obtain pore structural properties to compare the mathematical compaction models with actual porosity data from the Vienna Basin. Clear decreasing porosity depth trends imply that mechanical compaction was rather uniform in the central Vienna Basin. Comparing the Vienna Basin trend to global mudstone compaction trends, regional uplift causing erosion of up to ~ 500 m upper Miocene strata is inferred. A trend of increasing Rock-Eval parameters S1 and production index [PI = S1/(S1 + S2)] with decreasing capillary sealing capacity of the investigated mudstones possibly indicates vertical hydrocarbon migration through the low-permeable mudstone horizons. This observation must be considered in future top-seal studies for secondary storage applications in the Vienna Basin. Supplementary Information: The online version contains supplementary material available at 10.1007/s00531-023-02331-4.

Neural mechanism of spatio-chromatic opponency in the Drosophila amacrine neurons.

Visual animals detect spatial variations of light intensity and wavelength composition. Opponent coding is a common strategy for reducing information redundancy. Neurons equipped with both spatial and spectral opponency have been identified in vertebrates but not yet in insects. The Drosophila amacrine neuron Dm8 was recently reported to show color opponency. Here, we demonstrate Dm8 exhibits spatio-chromatic opponency. Antagonistic convergence of the direct input from the UV-sensing R7s and indirect input from the broadband receptors R1-R6 through Tm3 and Mi1 is sufficient to confer Dm8's UV/Vis (ultraviolet/visible light) opponency. Using high resolution monochromatic stimuli, we show the pale and yellow subtypes of Dm8s, inheriting retinal mosaic characteristics, have distinct spectral tuning properties. Using 2D white-noise stimulus and reverse correlation analysis, we found that the UV receptive field (RF) of Dm8 has a center-inhibition/surround-excitation structure. In the absence of UV-sensing R7 inputs, the polarity of the RF is inverted owing to the excitatory input from the broadband photoreceptors R1-R6. Using a new synGRASP method based on endogenous neurotransmitter receptors, we show that neighboring Dm8s form mutual inhibitory connections mediated by the glutamate-gated chloride channel GluClα, which is essential for both Dm8's spatial opponency and animals' phototactic behavior. Our study shows spatio-chromatic opponency could arise in the early visual stage, suggesting a common information processing strategy in both invertebrates and vertebrates.

Dynamic Signal Compression for Robust Motion Vision in Flies.

Sensory systems need to reliably extract information from highly variable natural signals. Flies, for instance, use optic flow to guide their course and are remarkably adept at estimating image velocity regardless of image statistics. Current circuit models, however, cannot account for this robustness. Here, we demonstrate that the Drosophila visual system reduces input variability by rapidly adjusting its sensitivity to local contrast conditions. We exhaustively map functional properties of neurons in the motion detection circuit and find that local responses are compressed by surround contrast. The compressive signal is fast, integrates spatially, and derives from neural feedback. Training convolutional neural networks on estimating the velocity of natural stimuli shows that this dynamic signal compression can close the performance gap between model and organism. Overall, our work represents a comprehensive mechanistic account of how neural systems attain the robustness to carry out survival-critical tasks in challenging real-world environments.

Glutamate Signaling in the Fly Visual System.

For a proper understanding of neural circuit function, it is important to know which signals neurons relay to their downstream partners. Calcium imaging with genetically encoded calcium sensors like GCaMP has become the default approach for mapping these responses. How well such measurements represent the true neurotransmitter output of any given cell, however, remains unclear. Here, we demonstrate the viability of the glutamate sensor iGluSnFR for 2-photon in vivo imaging in Drosophila melanogaster and prove its usefulness for estimating spatiotemporal receptive fields in the visual system. We compare the results obtained with iGluSnFR with the ones obtained with GCaMP6f and find that the spatial aspects of the receptive fields are preserved between indicators. In the temporal domain, however, measurements obtained with iGluSnFR reveal the underlying response properties to be much faster than those acquired with GCaMP6f. Our approach thus offers a more accurate description of glutamatergic neurons in the fruit fly.

Sterilization of bacterial spores by using supercritical carbon dioxide and hydrogen peroxide.

It was hypothesized that supercritical carbon dioxide (SC-CO(2)) treatment could serve as an alternative sterilization method at various temperatures (40-105 degrees C), CO(2) pressures (200-680 atm), and treatment times (25 min to 6 h), and with or without the use of a passive additive (distilled water, dH(2)O) or an active additive (hydrogen peroxide, H(2)O(2)). While previous researchers have shown that SC-CO(2) possesses antimicrobial properties, sterilization effectiveness has not been shown at sufficiently low treatment temperatures and cycle times, using resistant bacterial spores. Experiments were conducted using Geobacillus stearothermophilus and Bacillus atrophaeus spores. Spore strips were exposed to SC-CO(2) in commercially available supercritical fluid extraction and reaction systems, at varying temperatures, pressures, treatment times, and with or without the use of a passive additive, such as dH(2)O, or an active additive, such as H(2)O(2). Treatment parameters were varied from 40 to 105 degrees C, 200-680 atm, and from 25 min to 6 h. At 105 degrees C without H(2)O(2), both spore types were completely deactivated at 300 atm in 25 min, a shorter treatment cycle than is obtained with methods in use today. On the other hand, with added H(2)O(2) (<100 ppm), 6 log populations of both spore types were completely deactivated using SC-CO(2) in 1 h at 40 degrees C. It was concluded from the data that large populations of resistant bacterial spores can be deactivated with SC-CO(2) with added H(2)O(2)at lower temperatures and potentially shorter treatment cycles than in most sterilization methods in use today.

The Temporal Tuning of the Drosophila Motion Detectors Is Determined by the Dynamics of Their Input Elements.

Detecting the direction of motion contained in the visual scene is crucial for many behaviors. However, because single photoreceptors only signal local luminance changes, motion detection requires a comparison of signals from neighboring photoreceptors across time in downstream neuronal circuits. For signals to coincide on readout neurons that thus become motion and direction selective, different input lines need to be delayed with respect to each other. Classical models of motion detection rely on non-linear interactions between two inputs after different temporal filtering. However, recent studies have suggested the requirement for at least three, not only two, input signals. Here, we comprehensively characterize the spatiotemporal response properties of all columnar input elements to the elementary motion detectors in the fruit fly, T4 and T5 cells, via two-photon calcium imaging. Between these input neurons, we find large differences in temporal dynamics. Based on this, computer simulations show that only a small subset of possible arrangements of these input elements maps onto a recently proposed algorithmic three-input model in a way that generates a highly direction-selective motion detector, suggesting plausible network architectures. Moreover, modulating the motion detection system by octopamine-receptor activation, we find the temporal tuning of T4 and T5 cells to be shifted toward higher frequencies, and this shift can be fully explained by the concomitant speeding of the input elements.

Sterilizing Bacillus pumilus spores using supercritical carbon dioxide.

Supercritical carbon dioxide (SC CO(2)) has been evaluated as a new sterilization technology. Results are presented on killing of B. pumilus spores using SC CO(2) containing trace levels of additives. Complete killing was achieved with 200 part per million (ppm) hydrogen peroxide in SC CO(2) at 60 degrees C, 27.5 MPa. Addition of water to SC CO(2) resulted in greater than three-log killing, but this is insufficient to claim sterilization. Neither ethanol nor isopropanol when added to SC CO(2) affected killing.

A new follicle aspiration needle set is equally effective and as well tolerated as the standard needle when used in a prospective randomized trial in a large in vitro fertilization program.

OBJECTIVE: To compare the effectiveness and tolerability of two different 17-gauge follicle aspiration needles used in a large in vitro fertilization (IVF) program. DESIGN: Prospective, randomized single blinded study. SETTING: Private IVF center. PATIENT(S): Three hundred women undergoing IVF were randomly allocated at the time of oocyte retrieval to either the study needle (n = 151; follicle aspiration set [FAS] set) or the standard needle (n = 149; Echotip) used in the practice. Patients were blinded to the needle used. INTERVENTION(S): Transvaginal ultrasound-guided oocyte aspiration. MAIN OUTCOME MEASURE(S): Number of eggs retrieved/follicles visualized, retrieval time, mean amount of blood in the aspirate, egg damage, patient tolerance, physician acceptability, implantation, and pregnancy rate. RESULT(S): No differences were found in the number of eggs retrieved normalized to follicles visualized. Egg damage (4% vs. 4.2%), average blood in the aspirate (2.2 vs. 2.2), and retrieval time per egg (38 vs. 36 seconds) were similar with both needles. There were also no differences in pain or cramping scores (at 30 minutes and 24 hours after retrieval) or in the physicians' ratings of the two needles. The percentage of patients receiving an embryo transfer (ET), the implantation rate per embryo transfer, and the clinical pregnancy rate per embryo transfer were comparable for both needles. CONCLUSION(S): The FASs are equivalent.

Acceleration of regenerate ossification during distraction osteogenesis with recombinant human bone morphogenetic protein-7.

BACKGROUND: Bone-lengthening can be accomplished by means of distraction osteogenesis. In the present study, we examined the effect of a single dose of recombinant human bone morphogenetic protein-7 (rhBMP-7) on the rate of new-bone formation during distraction osteogenesis in the rat. METHODS: Fourteen Long-Evans rats were randomized into two groups of seven rats each. An external fixator was applied to the left femur, and a transverse osteotomy was performed. One group was treated with rhBMP-7 in an aqueous solvent, and the other group received the solvent alone and served as the control. rhBMP-7 was administered on the day of surgery by means of a single injection into the osteotomy gap. Distraction was started seven days after surgery at a rate of 0.25 mm every twelve hours. Distraction was continued for twenty days, resulting in a total of 10 mm of lengthening. The regenerate was monitored with use of radiographs and bone-mineral-density measurements at the conclusion of distraction and at two and four weeks after the cessation of distraction. The lengthened femora were harvested, and biomechanical studies were carried out to determine the stiffness and maximum torque to failure. RESULTS: Radiographs showed accelerated regenerate ossification in the BMP-7 group, with a larger amount of new bone compared with the control group. The bone-mineral-density values were dramatically enhanced on Day 20 in the BMP-7 group (103.6 +/- 12.6 mg/cm (2) ) compared with the control group (26.2 +/- 15.1 mg/cm (2) ). These differences continued to be greater at two and four weeks after the cessation of distraction. Normalized values of stiffness (percent stiffness) reached 76.5% +/- 5.4% in the BMP-7 group, compared with 6.6% +/- 0.5% in the control group. The percent maximum torque at failure was 81.1% +/- 1.2% in the BMP-7 group, compared with 20.8% +/- 0.3% in the control group. CONCLUSION: A single injection of rhBMP-7 at the time of osteotomy surgery stimulated the rate of regenerate ossification and increased bone-mineral density during distraction osteogenesis. The biomechanical properties of the newly formed bone were also increased by BMP-7 injection.

Description of an Audio-Based Paced Respiration Intervention for Vasomotor Symptoms.

Millions of women experience menopause-related hot flashes or flushes that may have a negative effect on their quality of life. Hormone therapy is an effective treatment, however, it may be contraindicated or unacceptable for some women based on previous health complications or an undesirable risk-benefit ratio. Side effects and the unacceptability of hormone therapy have created a need for behavioral interventions to reduce hot flashes. A variety of complex, multimodal behavioral, relaxation-based interventions have been studied with women (n = 88) and showed generally favorable results. However, currently extensive resource commitments reduce the translation of these interventions into standard care. Slow, deep breathing is a common component in most interventions and may be the active ingredient leading to reduced hot flashes. This article describes the content of an audio-based program designed to teach paced breathing to reduce hot flashes. Intervention content was based on skills training theory and music entrainment. The audio intervention provides an efficient way to deliver a breathing intervention that may be beneficial to other clinical populations.

Utilization of moiré interferometry to study the strain distribution within multi-layer thermoplastic elastomers.

The use of soft elastomeric cushion form bearings as an alternative material to ultra-high molecular weight polyethylene (UHMWPE) has been proposed in the literature as providing enhanced lubrication and lower friction. However, the abrupt change in stiffness between the bearing's soft contact layer and its rigid support substrate results in high shear stresses and leads to the debonding of the soft layer from the substrate. The use of functionally modulus-graded material has been proposed as a solution to this problem. This paper investigates the use of moiré interferometry to study the strain distribution within and across the interfaces of multi-layer elastomeric samples, which were fabricated as models for functionally modulus-graded materials. While this technique has been widely used to study the strain distribution in rigid materials and composites, this paper represents the first report of its application to low-modulus polymers at temperatures where they exhibit significant viscoelastic behavior. The results presented clearly demonstrate that the moiré interferometry technique can be successfully applied in the field of low-modulus elastomeric materials. The analysis of the moiré patterns suggests that the soft elastomeric material under the contact point was subjected to a compressive epsilonx, and was pushed sideways. The analysis also showed that the maximum shear strain occurred where the deformation was constrained, which could possibly lead to a local fatigue failure in the sample.

Experimental and numerical modeling of variable friction between nanoregions in coventional and crosslinked UHMWPE.

Recently, highly crosslinked UHMWPE components have been promoted for their high abrasive wear resistance over conventional UHMWPE (PE) in total joint replacement (TJR) prostheses to minimize osteolysis and consequent implant loosening. This study was aimed at investigating the role of friction gradients induced by localized coefficients of friction at both crystalline and amorphous nanoregions in PE, and crystalline and crosslinked nanoregions in crosslinked UHMWPE (XPE), in submicron wear debris generation. An abrasive wear study performed on both XPE and PE using atomic force microscopy (AFM) illustrated that the onset of plastic deformation for XPE occurred at a normal load that was approximately 3 times higher when compared to PE. Coefficients of friction (mu d) of 0.2, 0.35, and 0.61, experimentally derived using AFM, were used as representative mu d for crystalline, amorphous, and crosslinked nanoregions, respectively, in a numerical Hertzian model. An increase in mu (0.2 +/- 0.02, 0.35 +/- 0.01 and 0.6 +/- 0.04) was observed with a decrease in crystallinity and storage modulus at 22 degrees C. Using the Hertzian contact model, it was observed that variability in friction between nanoregions contributed to higher magnitude stresses for XPE (0.2 to 0.61; maximum sigma eff = 2.8) compared to PE (0.2 to 0.35; maximum sigma eff = 1.1) over a negligible thickness of the interfacial zone (IZ) between nanoregions. The experimentally observed increase in abrasive wear resistance of XPE could be attributed to an increase in the thickness of the interfacial zone between nanoregions with mu changing gradually from crystalline to crosslinked nanoregions, a situation that may not be observed with PE. This would cause a decrease in the friction gradient and resulting stresses thereby agreeing with the observed experimental higher abrasive wear resistance for XPE. However, in both PE and XPE, the presence of stress concentrations over a period of time could lead to irreversible damage of the material eventually generating submicron wear debris. Hence, semicrystalline, inhomogenous UHMWPE with several nanoregions (amorphous and crystalline) would be at a disadvantage for bearing application in terms of abrasive wear resistance compared to UHMWPE with relatively lower number of nanoregions and crosslinked nanoregions.