Pilot Study to Assess Changes in the Blink Reflex Across Age

ObjectiveThe objective was to conduct a preliminary study to access blink reflex parameters across age using the Eyestat.BackgroundThe blink reflex is a primitive brainstem response to an external stimulus is affected by multiple neurologic disorders, including those that affect the dopaminergic circuit that controls the eyelid. Our laboratory has utilized a potential objective measure to identify concussions within a college aged sport population called Eyestat, which measures changes in blink reflex parameters. Prior research cited significant differences in various blink reflex parameters between active play, concussion, and baseline. However, data with older, non-athlete populations has not defined.Design/MethodsOne hundred forty three subjects between the ages of 8–80 participated in this study. Once the subject was seated, the test sequence was initiated, in which the subject placed their face into the mask and 5 random air puffs were applied to the corner of the left or right eyes over a course of 20 seconds. High-speed videography (280 frames/sec.) captured the response of the subject's eyes before and after each stimuli.ResultsDescription statistics of the data indicated differences across age with the following parameters: Latency (ms): 46.02 (ages 8–21); 47.12 (ages 22–30); 48.96 (ages 31–40); 47.44 (ages 41–50); 55.20 (ages 51–60); and 55.39 (ages 61–80). Oscillations (qty): 14.10 (ages 8–21); 14.25 (ages 22–30); 12.19 (ages 31–40); 12.75 (ages 41–50); 9.98 (ages 51–60); and 9.78 (ages 61–80). Excursions (px): 127.57 (ages 8–21); 137.46 (ages 22–30); 135.34 (ages 31–40); 144.88 (ages 41–50); 147.72 (ages 51–60); and 148.85 (ages 61–80).ConclusionsAlthough more research is warranted to determine if these differences occur with a larger subject pool, this data substantiates the need for longitudinal assessments of the blink reflex as a potential biomarker, providing a non-invasive assessment of brain health in various populations.

Contrast Adaptation in Face Perception Revealed Through EEG and Behavior

Exposure to a face can produce biases in the perception of subsequent faces. Typically, these face aftereffects are studied by adapting to an individual face or category (e.g., faces of a given gender) and can result in renormalization of perceptions such that the adapting face appears more neutral. These shifts are analogous to chromatic adaptation, where a renormalization for the average adapting color occurs. However, in color vision, adaptation can also adjust to the variance or range of colors in the distribution. We examined whether this variance or contrast adaptation also occurs for faces, using an objective EEG measure to assess response changes following adaptation. An average female face was contracted or expanded along the horizontal or vertical axis to form four images. Observers viewed a 20 s sequence of the four images presented in a fixed order at a rate of 6 Hz, while responses to the faces were recorded with EEG. A 6 Hz signal was observed over right occipito-temporal channels, indicating symmetric responses to the four images. This test sequence was repeated after 20 s adaptation to alternations between two of the faces (e.g., horizontal contracted and expanded). This adaptation resulted in an additional signal at 3 Hz, consistent with asymmetric responses to adapted and non-adapted test faces. Adapting pairs have the same mean (undistorted) as the test sequence and thus should not bias responses driven only by the mean. Instead, the results are consistent with selective adaptation to the distortion axis. A 3 Hz signal was also observed after adapting to face pairs selected to induce a mean bias (e.g., expanded vertical and expanded horizontal), and this signal was not significantly different from that observed following adaption to a single image that did not form part of the test sequence (e.g., a single image expanded both vertically and horizontally). In a further experiment, we found that this variance adaptation can also be observed behaviorally. Our results suggest that adaptation calibrates face perception not only for the average characteristics of the faces we experience but also for the gamut of faces to which we are exposed.

Constructing benchmark test sets for biological sequence analysis using independent set algorithms

Statistical inference and machine learning methods are benchmarked on test data independent of the data used to train the method. Biological sequence families are highly non-independent because they are related by evolution, so the strategy for splitting data into separate training and test sets is a nontrivial choice in bench marking sequence analysis methods. A random split is insufficient because it will yield test sequences that are closely related or even identical to training sequences. Adapting ideas from independent set graph algorithms, we describe two new meth- ods for splitting sequence data into dissimilar training and test sets. These algo rithms input a sequence family and produce a split in which each test sequence is less than p % identical to any individual training sequence. These algorithms successfully split more families than a previous approach, enabling construction of more diverse benchmark datasets.

Tribologische Charakterisierung von Polymerfasern unter Trockenreibung, Mischreibung und Hydrodynamik mittels einer optimierten Pin-on-Disc-Prüfmethode

Based on the conventional pin-on-disc test method, a tribology test rig was adapted and optimized regarding its ability to characterize polymer fibers. The method is explained and first applications in the field of tribological characterization of single fibers are presented. The test sequence to investigate the polymer fibers (diameters of only a few 100 µm) is generated in such a way that data can be recorded continuously as a function of time in the wear range from a few 10 µm to several 100 µm even during the first few minutes. The test mode starts by applying line load and dynamically progresses to area load by changing the contact area during the measurement. It is shown that single fibers can be characterized with respect to their friction and wear properties in different tribological systems. The dependence of the wear rates of fiber material, surface roughness of the counter bodies and lubrication rates is presented.

Putting the Reservoir to Test: An Innovative Multi-Zone Drill Stem Test Method Revealed Critical Reservoir Characteristics, Horizontal and Vertical Connectivity for Field Development Decisions and Reserve Calculations

Information from dual-zone drill-stem tests (DSTs) and vertical interference tests, especially between oil and water zones, is very valuable for reservoir characterization under dynamic conditions. Despite the critical information that can be gathered for field development decisions, it is also an uncommon test type at a DST scale because of the advanced downhole test string design and operational complexity. This paper describes the objective-driven test design for a multi-layered carbonate reservoir and how the test sequence was modified in real-time to increase the value of information. An unconventional multi-zone well test with flexible on-demand control functionality was executed to resolve vital reservoir uncertainties for field development, including vertical interference between zones, individual zone characteristics and to confirm reservoir boundaries. Reservoir simulations were performed to decide the test sequence to create interference between different reservoir layers, while considering other test objectives, simultaneously. A DST string with wirelessly-activated downhole tools and flexible control options allowed to modify the test program on the fly, based on real-time data analysis and performance of each zone. One of the zones was also tested and characterized without flowing fluids to surface by making use of real-time downhole data. This complex, unorthodox well test operation was chosen to resolve multiple reservoir uncertainties in a single DST run, which would have normally required multiple different DSTs. Operations included flowing different zones individually, including acidizing operations, and the sequence was monitored and modified on the fly to maximize the value of data. Vertical interference between oil and water zones were also monitored to determine test conditions. Reservoir simulation studies helped choose the optimum test sequence to create the required interference by avoiding any disturbance in the interference data from other pressure transients during the test. During the test, downhole and surface testing data was transmitted to town in real-time and analyzed by the petro-technical team to guide the operational procedures. Downhole equipment was controlled wirelessly by acoustic commands to change the test design, depending on the data analysis. This thick carbonate formation was tested pre- and post-acid, to evaluate stimulation efficiency. Also, by testing the well at different flowrate and pressure conditions, information regarding future production well behavior was obtained. A low-pressure water zone was also tested without bringing fluids to surface, using a type of closed chamber test which was made possible by analyzing real-time downhole data from different depths. Multiple crucial objectives for field development decisions were planned and successfully obtained using an engineered DST string design. The confirmed reliability of complex DST string and wireless telemetry in difficult environment enabled well test efficiency gains to solve multiple challenging dynamic reservoir evaluation problems, simultaneously. These novel solutions bring new types of data and information to the exploration and appraisal teams to answer connectivity questions in a cost and time effective manner.

A Validated Methodology to Establish Structural Capacities for Subsea Connector Families

Understanding the structural limits of subsea connectors used in offshore environments is critical to ensure safe operations. The latest industry standards establish the requirement for physical testing to validate analysis methodologies for connector designs. In this paper, an analysis methodology, compliant with the latest API 17G standard, is presented for calculating structural capacities of non-preloaded connectors. The methodology has been developed for complex combined loading scenarios and validated using full-scale physical testing for different connector families. Detailed 3-D, non-linear, finite element models were developed for three different non-preloaded connections, which consisted of threaded and load shoulder connectors. A comprehensive set of combined tension and bending moment structural capacities at normal, extreme and survival conditions were calculated for each connection. The calculated capacities were validated for each connection by performing a test sequence using full-scale structural testing. A final tension or bending to failure test was also completed for each test connection to validate the physical failure mode, exceeding the latest API 17G requirements. For all connections tested, capacities calculated using the methodology were validated from the successful completion of the test sequences. The physical failure modes of the test connections also matched the predicted failure modes from the FEA, and the tensile or bending moment loading at physical collapse exceeded that predicted by the global collapse of the FEA model. Using the validated approach described in this paper significantly reduces the requirement of physical testing for connector families, establishing confidence in the structural limits that are critical for safe operations.

Cold Welding in Hold Down Points of Space Mechanisms Due to Fretting When Omitting Grease

Cold welding refers to an effect related to space (vacuum). The heavy vibrations during a launch subject interfaces (hold down points) to oscillating motions which may lead to formation of a kind of “friction weld”. If so, these mechanisms may get stuck, and deployment will be hindered. This may endanger the functionality of the mission (instruments) or even the whole spacecraft (if solar panels do not open). Several studies have been done to characterize material combinations (including coatings) for their ability to cold welding in space. Meanwhile, also during launch grease free contacts are demanded. If grease hat to be omitted, the risk of cold welding under fretting was found to increase (when testing in high vacuum). To rate this risk under launch conditions, the test method was recently extended for testing under launch conditions. The new tests procedure consists of fretting applied in the sequence in air, low vacuum and high vacuum. The paper shall present first results gained with this new method of testing in launch conditions and compare them to previous studies done in vacuum. Following the need of space industry on mechanisms for launch and in-orbit life, a first set of combinations of materials and coatings were selected for this new test sequence where fretting is now applied in a sequence of air, low vacuum and high vacuum. Under this sequence, the measured levels of adhesion and it’s evolvement was found to differ strongly from tests done formerly. The paper outlines these first results and compares them to existing data.

Piezoresistive bond lines for timber construction monitoring—experimental scale-up

Several laboratory studies and experiments have demonstrated the usability of polymer films filled with electrically conductive filler as piezoresistive material. Applied to adhesives, the glue lines of wood products can achieve multifunctional—thus bonding and piezoresistive/strain sensing—properties. Based on critical load areas in timber constructions, upscaled test setups for simplified load situations were designed, especially with regard to a stress-free electrical contact. In a second step, another upscaling was done to small glulam beams. Based on an experimental test sequence, the piezoresistive reactions as well as the behaviour until failure were analysed. The results show in all cases that a piezoresistive reaction of the multifunctionally bonded specimens was measurable, giving a difference in the extent of relative change. Additionally, measured phenomena like inverse piezoresistive reactions, electrical resistance drift and the absence of a piezoresistive reaction were discussed, based on additional strain analysis by digital image correlation. A model of macroscopic and microscopic strains influencing the piezoresistive reaction of the electrically conductive bond line in wood was used to explain all experimental results. Finally, a first scale-up of piezoresistive bond lines from laboratory samples to glulam beams was possible and successful.