Constant Intensity Research Articles

Similarity of competing risks models with constant intensities in an application to clinical healthcare pathways involving prostate cancer surgery

The recent availability of routine medical data, especially in a university-clinical context, may enable the discovery of typical healthcare pathways, that is, typical temporal sequences of clinical interventions or hospital readmissions. However, such pathways are heterogeneous in a large provider such as a university hospital, and it is important to identify similar care pathways that can still be considered typical pathways. We understand the pathway as a temporal process with possible transitions from a single initial treatment state to hospital readmission of different types, which constitutes a competing risks setting. In this article, we propose a multi-state model-based approach to uncover pathway similarity between two groups of individuals. We describe a new bootstrap procedure for testing the similarity of constant transition intensities from two competing risk models. In a large simulation study, we investigate the performance of our similarity approach with respect to different sample sizes and different similarity thresholds. The studies are motivated by an application from urological clinical routine and we show how the results can be transferred to the application example.

Modeling and optimizing by the response surface methodology of the Pb(II)-removing effectiveness from a soil by electrokinetic remediation

ABSTRACT Herein, we report the optimization of Pb(II) ions removal from soil by electrokinetic remediation, using the response surface methodology (RSM) based on central composite design (CCD) describing individual and interactive effects of three chosen variables: the current intensity (I), electrolyte concentration (C) and remediation time (t). Sulfuric acid was selected as the electrolyte medium. The physicochemical properties of the soil were well characterized. The electrokinetic remediation (EKR) experiments were performed in galvanostatic mode, at constant current intensity. The lead Pb(II) content was measured using the atomic absorption spectrophotometer (AAS). Designing and modeling of the experimental runs were done using the Design Expert software. The results establish that the quadratic polynomial model matches the experimental data between the removal efficiency (η %) and the influencing factors. The obtained p-values (<0.05) through ANOVA analysis reveal a significant term, suggesting that the model was satisfactory. The significance of influencing factors increases is in that order: I < C (H2SO4) < t; increasing the remediation time translates into higher removal efficiencies. The statistical optimization strategy used in this study was successful in attaining the maximal lead removal of 86.79% using current intensity of 0.05 A, H2SO4 concentration of 0.05 M, and remediation time of 24 h 38 min. Ultimately, besides the great potential of the electrokinetic remediation for efficient removal of Pb(II) species, the RSM-based CCD is a promising and valuable tool for modeling and optimizing their elimination from contaminated soils.

Вдосконалення методики планування тренувальних навантажень швидкісно-силової спрямованості футболістів у річному циклі підготовки

The rapid development of football, accompanied by a constant growth and intensity of physical activity in the training and competitive processes of football players, requires the need to search for new forms, means and methods of organizing the educational and training process. The purpose of the study is to develop a program of speed-strength training for qualified football players, aimed at increasing the stability of performing speed-strength actions. Material and methods: in accordance with the goals and objectives, the research program included methods of analysis and generalization of scientific and methodological literature, pedagogical observations, pedagogical testing, pedagogical experiment, methods of mathematical statistics. The study was conducted with the players of the team "FC VPK-Agro" - participants of the Сhampionship of Ukraine among the teams of the First League. 20 football players of the team participated in resepctive research. The research was carried out in 2 stages. At the first stage, the dynamics of the speed-strength qualities of the players in the annual cycle was determined. At the second stage, an experimental verification of the developed methodology for improving the development of speed-strength qualities was carried out. Results: the article presents the level of development of the speed-strength qualities of football players and their dynamics in the annual training cycle. It was determined that the data obtained on the level of development of the speed-strength qualities of football players at the end of the competitive period emphasized the inconsistency with modern requirements for high-level players. It has been established that in the competitive period the dynamics of the indicators of the speed-strength qualities of the subjects using traditional training programs is characterized by a statistically significant decrease in the second part of the championship. The defining features of the experimental methodology for training football players are to increase the period of preparation from 20% to 45% of the partial amount of speed-strength exercises performed mainly in a repeated mode and the use of at least 80% of specialized in-game training cycles, 50% of which should consist of exercises of a speed-strength. Conclusions: The optimal ratio of exercises depending on their specialization at each of the three stages of the annual cycle is determined. The practical application of the experimental program made it possible to increase the amount of speed work in the training process and achieve a relatively stable speed of all jerks and accelerations during matches throughout the year.

The effects of increasing preservative uptake by microwave pre-treatment on the microstructure and mechanical properties of Oriental spruce wood

ABSTRACT In the microwave (MW) pre-treatment process, a constant MW energy intensity of 2158 MJ/m3 was applied by using 925 W (3700 sec.), 1295 W (2640 sec.) and 1850 W (1850 sec.) powers. Tanalith-E preservative material was used to determine the increase in impregnability of MW pre-treated wood. The mechanical properties of the treated wood specimens were tested to determine the degradation caused by exposure to the MW radiation. Additionally, scanning electron microscope (SEM) was used to determine the changes in wood microstructure with the effect of microwave pre-treatment. According to the impregnations, the average preservative material retention rates increased 62% for the specimens with MW groups, compared to the reference specimens. The mechanical properties of the MW pre-treated specimens decreased by (average) 5% in compression strength, 12% in the bending strength and 16% in the modulus of elasticity. SEM observations of the reference specimens showed that there were many aspirated bordered pits before MW pre-treatment. After the MW pre-treatment, parts of the pit membranes were damaged. The torus ruptured and cracked, while the structure of the micro-fibrils on the margo remained intact. In the observations of the intercellular microstructure of wood, it was observed that micro cracks with a width of 1–10 μm were formed.

Analysis of deformation dynamics of droplet in oil under the CPG electric field

Given that the common constant frequency pulse electric field cannot meet the requirements of the optimal demulsification frequency change in the demulsification process, a chaotic pulse group (CPG) electric field with chaotic group frequency, constant field intensity and group pulse number is proposed to excite all droplets in oil to resonate and improve the demulsification efficiency. However, the vibration and deformation characteristics of droplet in emulsion oil under the CPG electric field is unclear. Therefore, the droplet deformation dynamic model under the CPG electric field is established by applying the finite element method. The influences of duty cycle and group pulse number on droplet deformation are analyzed, and the mechanism of droplet relaxation in CPG electric field is investigated. Results show that the optimal duty cycle is 0.5 and the optimal group pulse number is 3. The droplet tends to be resonant when the frequency of the electric field group is close to its resonant frequency, and its steady vibration mainly depends on the consistency of the state of the droplet after the end of the latter pulse with that of the former pulse.

A Propensity Score–Matched Comparison Between Knotless Layer-by-Layer and En Masse Suture Bridge Techniques for Delaminated Rotator Cuff Tears

Background: Because the articular layer is more prone to retraction than the bursal layer of the supraspinatus tendon, it is important to restore each layer anatomically while repairing delaminated rotator cuff tears (RCTs). Purpose: To compare clinical outcomes and tendon integrity between knotless layer–by–layer and conventional en masse repair techniques for delaminated RCTs. Study Design: Cohort study; Level of evidence, 3. Methods: We retrospectively reviewed data from 174 consecutive patients with delaminated RCTs treated by arthroscopic suture bridge repair. Only 115 patients with medium to large supraspinatus tears with delamination were included. The 33 patients treated using the knotless layer–by–layer technique (group 2) were matched 1:1 with patients treated using en masse repair with the suture bridge technique (group 1) based on propensity scores. Tendon thickness was measured on magnetic resonance imaging (MRI). Signal changes in the bursal, articular, and intratendinous layers were assessed using T2-weighted MRI. Results: Postoperatively, statistically significant improvements were seen in both groups compared with preoperatively functional scores. At the final follow–up, there was a statistically significant difference in the Constant score, which was higher in group 2 than in group 1 (91.4 ± 6.0 and 84.3 ± 16.4, respectively; P = .005). There was 1 case of a retear in each group, representing a 3% retear rate. Group 2 had thicker tendons than group 1 (6.9 ± 1.1 and 6.0 ± 1.2 mm, respectively; P = .017). On T2-weighted MRI, a low signal intensity in the articular layer was more common in group 2 (P = .046). Conclusion: En masse repair using the suture bridge technique and the knotless layer–by–layer technique were both effective. Regarding tendon healing, no significant differences were seen in retear rates. However, superior results in terms of the Constant score, tendon thickness, and signal intensity in the articular layer were observed using the knotless layer–by–layer technique.

Viability Improvement of Three-Dimensional Human Skin Substitutes by Photobiomodulation during Cultivation.

Three-dimensional (3D) cultured skin containing vascular networks is a useful skin substitute that enables rapid reperfusion after transplantation. During its cultivation, however, insufficient nutrient delivery to the thick cultured tissue from the surrounding culture medium decreases the tissue viability. To solve this problem, in this study, we applied photobiomodulation (PBM), which can optically activate the electron transport chain of mitochondria, to human 3D skin cultures constructed using the layer-by-layer cell coating technique. PBM was applied once 5 days after the start of epidermal differentiation using a light-emitting diode array with a center wavelength of 440, 523, 658 or 823 nm at a constant light intensity of 15 mW cm-2 for 50 or 600 s. Two days after PBM, we assessed the viability of the tissues by a water-soluble tetrazolium-8 assay, adenosine triphosphate measurements and live/dead cell imaging, and the results showed that the PBM at 823 nm for 50 s (0.75 J cm-2 ) significantly improved the viability of the 3D-cultured skin.

The effects of blue and red light color combinations on the growth and immune performance of juvenile steelhead trout, Oncorhynchus mykiss

To examine the growth and immune response of steelhead trout (Oncorhynchus mykiss) under conditions of differing light color, we investigated the effects of different red and blue light color combinations on plasma non-specific immunity, hepatic antioxidant capacity, and GH/IGF-1 axis gene expression in juvenile steelhead trout (initial weight: 34.67 ± 2.69 g). The 16-week trial was set up with six treatments in which light color varied at a constant light intensity of 150 lx: 12 h white light + 12 h dark (12 W), 12 h blue light + 12 h dark (12B), 12 h red light + 12 h dark (12 R), 1.5 h blue light + 9 h red light + 1.5 h blue light + 12 h dark (3B9R), 3 h blue light + 6 h red light + 3 h blue light + 12 h dark (6B6R), total 12 h of blue and red light + 12 h dark (T12BR). The results revealed that the 12B and 3B9R light environments significantly enhanced plasma immunoglobulin M levels in steelhead trout, and that the 3B9R light environment also promoted significant increases in the gene expression of hepatic growth hormone receptor, insulin-like growth factor 1, and insulin-like growth factor-binding protein. The 3B9R light environment was also found enhance the antioxidant capacity of trout by increasing hepatic superoxide dismutase, catalase, and glutathione peroxidase activities. In contrast, trout exposed to the 6B6R light environment showed significant reductions in growth and immune performance, and there were similar reductions in hepatic antioxidant capacity. Furthermore, fish exposed to the 12R light environment were found to be characterized by elevated levels of lipid peroxidation and malondialdehyde, which are indicative of hepatic stress. In addition, we observed that in response to light variation, there were elevations in the activities of glutamic oxaloacetic transaminase and lactic dehydrogenase in the plasma of steelhead trout, thereby indicating an inhibition of cardiomyocyte function. In summary, our findings indicate that a 3B9R light environment simulates the blue-red-blue daily rhythm of light color variation in natural underwater environments, which is beneficial with respect to enhancing the growth and immunity of steelhead trout, and could accordingly be used to provide suitable light conditions in commercial trout production. However, sudden changes in light color should be avoided in the aquaculture of trout.

Analysis of a MAP/M/1/N Queue with Periodic and Non-Periodic Piecewise Constant Input Rate

This paper considers a queuing system with a finite buffer, a constant main MAP flow, and an additional periodic (non-periodic) Poisson piecewise-constant flow of customers. The eigenvalues of the probability translation matrix of a Kolmogorov system with constant input intensities is analyzed. The definition of the transition mode time based on the analysis of the probability translation matrix determinant is introduced for the first time. An analytical solution to the Kolmogorov equation system for a queuing system with piecewise constant arrival and service intensities is found, the solutions for a queuing system with periodic arrival and service intensities are analyzed, and numerical calculations illustrating this approach are presented.

Effects of repeated exposure to escalating versus constant punishment intensity on response allocation.

The present experiment investigated the effects of 1) repeated exposures to escalating punishment intensities and 2) repeated exposure to punishment after periods of vacation on response allocation between punished and unpunished responding in three groups of rats. The first group (intensity + vacation) experienced repeated exposures to escalating punishment intensities after a period of vacation (i.e., return to baseline) from punishment. The second group (intensity-only) experienced repeated exposures to escalating punishment intensities without vacation from punishment. The third group (vacation-only) experienced repeated exposures to a constant punishment intensity after a period of vacation from punishment. Results showed that superimposition of punishment on one of two concurrently available responses decreased allocation toward the punished response and increased allocation toward the unpunished response. Furthermore, greater changes in allocation were observed with the introduction of a moderate constant intensity than with the introduction of a low intensity that increased across sessions. Reexposure to punishment had different effects between the groups. Although there was evidence that high shock intensities can enhance the efficacy of lower intensities to shift allocation away from the punished response and toward the unpunished response, there was little evidence of changes in response allocation with reintroduction of punishment after a period of vacation.

Front-like expansion and arrest of programmed cell death in brown banana spots

The spot patterns on bananas are a striking case of biological pattern formation and—as a qualitative ripeness indicator—linked to 50 million tons of wasted food per year. Ripening bananas develop these senescent spots as phenolic compounds are enzymatically oxidized and cellular integrity is lost. We characterize the dynamics of the spot expansion and their nucleation rates based on time-lapse movies. Spots nucleate for about 2 days yielding a typical density of 8 spots/cm2. The expansion is initially diffusion controlled and the effective diffusion coefficient decreases with nucleation time from 1.3 to 0.4 mm2 d−1. During and after expansion, the browning fronts maintain a steep and constant intensity gradient. We quantitatively reproduce these features by a reaction–diffusion model that considers the local oxygen concentration and browning degree of the peel. All model parameters are based on measurements and front stalling is explained by decreasing oxygen levels in the nucleation sites.

Blue and Red Light Color Combinations Can Enhance Certain Aspects of Digestive and Anabolic Performance in Juvenile Steelhead Trout Oncorhynchus mykiss

The light spectrum varies with the altitude of the sun and shows different light colors in clear water. In this study, we aimed to investigate the response of juvenile steelhead trout Oncorhynchus mykiss (34.67 ± 2.69 g initial weight) under different light color conditions. The effects of different blue and red light combinations on plasma biochemical parameters, digestive enzyme activity, and RNA/DNA ratio were assessed in trout over 16 weeks. Six treatments were randomly assigned to 24 tanks with four replicates per treatment: a constant light intensity of 150 lx: 12 h white light then 12 h dark (12W); 12 h blue light then 12 h dark (12B); 12 h red light then 12 h dark (12R); 1.5 h blue light, 9 h red light, 1.5 h blue light, then 12 h dark (3B9R); 3 h blue light, 6 h red light, 3 h blue light, then 12 h dark (6B6R); and 12 h of both blue and red light then 12 h dark (T12BR). Fish exposed to the 3B9R light environment showed significantly increased plasma levels of total protein (TP), enhanced activities of midgut lipase, trypsin, and gastric lipase; and increased RNA content in the liver and muscle tissue to promote protein synthesis efficiency, thereby improving digestive and anabolic performance compared to fish in the other treatments. This indicates that steelhead trout have adapted well to such variable light conditions during long-term evolution. In contrast, trout exposed to the 6B6R light environment showed significant reductions in plasma glucose, TP, and triglyceride levels, decreased activity of gastrointestinal digestive enzymes, and reduced protein synthesis capacity in the muscle and liver, resulting in weakened digestive and anabolic performance. Furthermore, despite the high RNA content and RNA/DNA ratio in fish exposed to a 12R light environment, relatively high plasma cholesterol and triglycerides levels were observed, which might indicate oxidative stress. Therefore, this light is not considered suitable for long-term cultivation. In conclusion, the 3B9R treatment was the optimal light condition tested and can be used to improve the digestive and anabolic performance of steelhead trout.

Calibration method of ultra-low emission particulate concentration measurement by light scattering method

Abstract To reduce the error caused by optical device pollution and background value drift in the measurement process of ultra-low emission particulate concentration by light scattering method, an on-line calibration method which can realize self-check and full-range calibration was put forward. The single light source spectral method was used to set up calibration light path, through a strong emphasis on technology achieving light signal extraction. The calibration effect was evaluated based on the dust tunnel system. The results show that the light intensity-modulated technique can significantly improve the measurement accuracy of low concentration particles compared with the constant light intensity technology. When the concentration of particles to be measured is higher than 500 μg/m³, the relative error between the measurement results of the experimental prototype and those of the filter membrane weighing method is less than 10 %. The optimal calibration period of the measuring instrument is 3 hours. When the variation deviation from the calibration light intensity of light intensity modulation is less than 2 %, the relative error between the particle concentration measurement result and the filter membrane weighing method is less than 10 %.

Effects of electronic correlation on the high harmonic generation in helium: A time-dependent configuration interaction singles vs time-dependent full configuration interaction study.

In this paper, we investigate the effects of full electronic correlation on high harmonic generation in the helium atom subjected to laser pulses of extremely high intensity. To do this, we perform real-time propagations of helium atom wavefunction using quantum chemistry methods coupled to Gaussian basis sets. Calculations are performed within the real-time time-dependent configuration interaction framework at two levels of theory: time-dependent configuration interaction with single excitations (uncorrelated method) and time-dependent full configuration interaction (fully correlated method). The electronic wavefunction is expanded in Dunning basis sets supplemented with functions adapted to describing highly excited and continuum states. We also compare the time-dependent configuration interaction results with grid-based propagations of the helium atom within the single-active-electron approximation. Our results show that when including the dynamical electron correlation, a noticeable improvement to the description of high harmonic generation (HHG) can be achieved in terms of, e.g., a more constant intensity in the lower energy part of the harmonic plateau. However, such effects can be captured only if the basis set used suffices to reproduce the most basic features, such as the HHG cutoff position, at the uncorrelated level of theory.

The Efficacy of Remotely Supervised Transcranial Direct Current Stimulation on Conditioned Pain Modulation in Older Adults with Knee Osteoarthritis Pain

Osteoarthritis is a leading cause of pain, impaired daily function, and disability in older adults. Pharmacological and surgical interventions can increase the risk of side effects among older adults, and therefore, nonpharmacological interventions are promoted by the National Pain Strategy. Specifically, transcranial direct current stimulation (tDCS) targeting central nervous system pain processing has received growing attention for the treatment of chronic pain. Remotely supervised tDCS extended the analgesic properties of tDCS from the clinical setting to benefit participants in the comfort of their homes. Thus, we sought to assess the preliminary efficacy of tDCS on conditioned pain modulation in adults with knee OA pain. We conducted a single-group, open-label study in 20 community-dwelling older adults (ages 50–85 years) with knee osteoarthritis. tDCS with anode over the primary motor cortex and cathode with contralateral supraorbital region was applied with a constant current intensity of 2mA for 20 minutes every weekday for two weeks (Monday to Friday) for a total of 10 sessions. All tDCS sessions were remotely supervised by the trained research staff using secure videoconferencing software. Conditioned pain modulation (CPM) was measured by determining the change in pressure pain threshold on the trapezius immediately following immersion of the contralateral hand up to the wrist in a cold-water bath for up to one minute. The mean age of participants was 61 years (SD = 7 years), and 75% were female. CPM was significantly increased from 0.9 (SD=0.7) to 1.3 (SD=0.6) at the end of treatment (effect size = 0.4). Our preliminary results show that tDCS increased CPM in adults with knee OA. Randomized controlled trials with larger samples and longer-term follow-ups are needed to corroborate these promising findings regarding the effects of remotely supervised tDCS. This study was supported in part by the Theodore J. and Mary E. Trumble Endowment from The University of Texas Health Science Center at Houston and National Institute of Nursing Research (R15NR018050, R01NR019051).

Monitoring of pesticide amount in water and drinkable food by a fluorescence-based biosensor.

The identification of pollutants is crucial to protect water resources and ensure food safety. The available analytical methodologies allow reliable detection of organic pollutants such as pesticides; however, there is the need for faster, direct and continuous methodologies for real‐time monitoring of pesticides. Fluorescent‐based biosensors have been recently proposed as a valid alternative due to their advantage of being easy, cheap and specific. In this context, the aim of the present EU‐FORA fellowship programme was to develop and apply a fluorescence‐based biosensing device for the detection of organophosphate (OP) pesticides in water samples and drinkable food. The study was addressed using a mutant of the thermostable esterase‐2 from Alicyclobacillus acidocaldarius (EST2‐S35C) as a bioreceptor for OP pesticides. The use of EST2 involves some significant advantages including specificity and affinity towards OPs, and high stability over time in a different range of temperatures and pH. The protein was labelled to the fluorescent probe IAEDANS and fluorescence measurements of quenching in solution and in immobilised form were performed. The results showed good stability and sensitivity, reaching low limits of detection and quantification and a constant signal intensity over time. The addition of paraoxon quenched the fluorescence of the complex, reaching a plateau at 100 pmol paraoxon. The decrease of enzymatic activity of EST2‐S35C‐IAEDANS in the presence of paraoxon correlated the inhibition of the labelled enzyme with the decrease in fluorescence. The results from the application of the biosensor with real samples showed a decrease in fluorescence in surface water samples, contaminated by OPs. The use of the developed fluorescence‐based biosensor demonstrated its applicability for real samples monitoring and could ensure the production of large amounts of data in a short period of time which can be used to address environmental and food safety risk assessment.

A systematic map of demographic data from elephant populations throughout Africa: implications for poaching and population analyses

Abstract The crisis facing Africa’s elephant populations is a notorious example of ongoing wildlife declines caused by illegal harvesting. Targeted conservation interventions require detailed knowledge about changes in population sizes and the effect of illegal activities. However, accurately quantifying poaching intensity is a difficult task: commonly calculated from ranger‐based carcass‐encounter data, the proportion of illegally killed elephants (PIKE) is a function of poaching and background mortality. Hence, at constant poaching intensity, PIKE decreases with increasing natural mortality and also with hunting, management interventions, and other anthropogenically induced deaths. Natural mortality is often more difficult to quantify with accuracy than mortality due to illegal killing, as elephants that die naturally are more likely to be missed than those taken by poachers. In recent analyses, constant background mortality rates were assumed. Yet, for example climate‐driven fluctuations in natural mortality, if not quantified and accounted for, may lead to biased estimates of poaching intensity. Varying background mortality rates can be accounted for in the analysis of PIKE, but this requires near‐complete counts of natural and management‐related deaths and hunting records. Carefully developed population models, which simulate population dynamics and demographic changes while accounting for variation in environmental conditions and management strategies, are alternatives. However, successful calibration of such models requires integrating comprehensive demographic data. We systematically review the scientific and ‘grey’ literature on African elephant demography with the objective of facilitating poaching and population analysis possibilities through an inventory of information relevant to demography. Our screening of 10900 publications resulted in the review of relevant information provided by 431 studies from 420 study sites throughout Africa. From these, we extracted demographic data collected between 1900 and 2017, and collated them in the newly created African Elephant Demographic Database (AEDD; 10.6084/m9.figshare.19387085). We found 37 natural mortality estimates from five different study sites. Other mortality data, demographic rates, and age‐ and sex‐structured population data were substantially more abundant, both temporally and spatially. This new collection of demographic rates, age‐ and sex‐structured population data, and cause‐partitioned mortality estimates identifies spatial and temporal data gaps and provides prior information needed for African elephant population models. Closing these data gaps and subsequent analyses of realistic population models may aid elephant conservation via improved policies, legislation, and protection.

The effect of acute intermittent hypoxia on human limb motoneurone output.

What is the central question of this study? Does a single session of repeated bouts of acute intermittent hypoxic breathing enhance the motoneuronal output of the limb muscles of healthy able-bodied participants? What is the main finding and its importance? Compared to breathing room air, there were some increases in motoneuronal output following acute intermittent hypoxia, but the increases were variable across participants and in time after the intervention and depended on which neurophysiological measure was checked. Acute intermittent hypoxia (AIH) induces persistent increases in output from rat phrenic motoneurones. Studies in people with spinal cord injury (SCI) suggest that AIH improves limb performance, perhaps via postsynaptic changes at cortico-motoneuronal synapses. We assessed whether limb motoneurone output in response to reflex and descending synaptic activation is facilitated after one session of AIH in healthy able-bodied volunteers. Fourteen participants completed two experimental days, with either AIH or a sham intervention (randomised crossover design). We measured H-reflex recruitment curves and homosynaptic post-activation depression (HPAD) of the H-reflex in soleus, and motor evoked potentials (MEPs) evoked by transcranial magnetic stimulation (TMS) and their recruitment curves in first dorsal interosseous. All measurements were performed at rest and occurred at baseline, 0, 20, 40 and 60min post-intervention. The intervention was 30min of either normoxia (sham, ≈0.21) or AIH (alternate 1-min hypoxia [ ≈0.09], 1-min normoxia). After AIH, the H-reflex recruitment curve shifted leftward. Lower stimulation intensities were needed to evoke 5%, 50% and 99% of the maximal H-reflex at 40 and 60min after AIH (P<0.04). The maximal H-reflex, recruitment slope and HPAD were unchanged after AIH. MEPs evoked by constant intensity TMS were larger 40min after AIH (P=0.027). There was no change in MEP recruitment or the maximal MEP. In conclusion, some measures of the evoked responses from limb motoneurones increased after a single AIH session, but only at discrete time points. It is unclear to what extent these changes alter functional performance.

Comparing Stress Corrosion Cracking Behavior of Additively Manufactured and Wrought 17-4PH Stainless Steel

As a high-strength corrosion-resistant alloy, stress corrosion cracking (SCC) behavior is a key consideration for the conventional, wrought form of 17-4PH stainless steel. With the increasing popularity of the additively manufactured (AM) form of 17-4PH, understanding the SCC behavior of AM 17-4PH will be similarly critical for its presumed, future applications. The current study quantifies and compares the SCC behavior of both the wrought form, as a baseline, and AM form of 17-4PH at peak-aged (∼1,200 MPa) and overaged (∼1,050 MPa) strength levels. The laser powder bed fusion technique followed by post-process hot isostatic press (HIP), solution annealing, and aging heat treatments is used to produce AM 17-4PH with similar microstructures and strength levels to wrought 17-4PH and facilitate the comparison. SCC behavior is quantified using fracture mechanics-based rising (dK/dt = 2 MPa√m/h) and constant (dK/dt = 0 MPa√m/h) stress intensity tests in neutral 0.6 M NaCl at various applied potentials. Limited SCC susceptibility was observed at open-circuit and anodic potentials for both forms of 17-4PH. At cathodic applied potentials, AM consistently underperforms wrought with up to 5-fold faster crack growth rates and 200 mV to 400 mV wider SCC susceptibility ranges. These results are interrogated through microstructural and fractographic analysis and interpreted through a decohesion-based hydrogen-assisted crack model. Initial analyses show that (1) increased oxygen content, (2) porosity induced by argon processing, and (3) slow cooling (310°C/h) during conventional HIP processing might contribute to degraded SCC performance in AM 17-4PH.

Spatially strongly confined atomic excitation via a two dimensional stimulated Raman adiabatic passage.

We consider a method of sub-wavelength superlocalization and patterning of atomic matter waves via a two dimensional stimulated Raman adiabatic passage (2D STIRAP) process. An atom initially prepared in its ground level interacts with a doughnut-shaped optical vortex pump beam and a traveling wave Stokes laser beam with a constant (top-hat) intensity profile in space. The beams are sent in a counter-intuitive temporal sequence, in which the Stokes pulse precedes the pump pulse. The atoms interacting with both the traveling wave and the vortex beam are transferred to a final state through the 2D STIRAP, while those located at the core of the vortex beam remain in the initial state, creating a super-narrow nanometer scale atomic spot in the spatial distribution of ground state atoms. By numerical simulations we show that the 2D STIRAP approach outperforms the established method of coherent population trapping, yielding much stronger confinement of atomic excitation. Numerical simulations of the Gross-Pitaevskii equation show that using such a method one can create 2D bright and dark solitonic structures in trapped Bose-Einstein condensates (BECs). The method allows one to circumvent the restriction set by the diffraction limit inherent to conventional methods for formation of localized solitons, with a full control over the position and size of nanometer resolution defects.