Minimal Threshold Research Articles

"From Where I Stand": using multiple anchors yields different benchmarks for meaningful improvement and worsening in the rheumatoid arthritis flare questionnaire (RA-FQ).

The Rheumatoid Arthritis Flare Questionnaire (RA-FQ) is a patient-reported measure of disease activity in RA. We estimated minimal and meaningful change from the perspective of RA patients, physicians, and using a disease activity index. Data were from 3- to 6-month visits of adults with early RA enrolled in the Canadian Early Arthritis Cohort. Participants completed the RA-FQ, the Patient Global Assessment of RA, and the Patient Global Change Impression at consecutive visits. Rheumatologists recorded joint counts and MD Global. Clinical Disease Activity Index (CDAI) scores were computed. We compared mean RA-FQ change across categories using patients, physicians, and CDAI anchors. The 808 adults were mostly white (84%) women (71%) with a mean age of 55 and moderate-high disease activity (85%) at enrollment. At V2, 79% of patients classified their RA as changed; 59% were better and 20% were worse. Patients reporting they were a lot worse had a mean RA-FQ increase of 8.9 points, whereas those who were a lot better had a -6.0 decrease. Minimal worsening and improvement were associated with a mean 4.7 and -1.8 change in RA-FQ, respectively, while patients rating their RA unchanged had stable scores. Physician and CDAI classified more patients as worse than patients, and minimal and meaningful RA-FQ thresholds differed by group. Thresholds to identify meaningful change vary by anchor used. These data offer new evidence demonstrating robust psychometric properties of the RA-FQ and offer guidance about improvement or worsening, supporting its use in RA care, research, and decision-making.

Diagnostic Utility of Synovial Fluid Cell Counts and CRP in Pediatric Knee Arthritis: A 10-Year Monocentric, Retrospective Study.

Background: Orthopedic surgeons often use the intra-articular white blood counts (WBCs) and the percentage of polymorphonuclear cells (PMN) in the diagnosis of an acute swollen and painful knee joint in children. Today, there is no established threshold for the synovial WBC, and their differentiation, as indicative of native joint knee bacterial arthritis. We determine the sensitivity and specificity of synovial WBCs and PMN percentages in the prediction of a community-acquired, acute bacterial native joint septic arthritis (SA) in the pediatric population. Methods: A retrospective study on healthy children 0–16 years of age who underwent knee joint aspiration for a community-acquired, acute irritable knee effusion in our tertiary-care children’s hospital between May 2009 and April 2019 was conducted. We divided the study population into two groups according to the detection of bacterial arthritis in the synovial fluid (bacterial arthritis versus its absence) and compared the intra-articular leukocyte and C-reactive protein (CRP) levels. Results: Overall, we found a statistically significant difference regarding the total CRP (p = 0.017), leukocyte or PMN counts (p ≤ 0.001 in favor of a bacterial arthritis). In contrast, the percentage of the neutrophils was not determinant for the later confirmation of bacterial pathogens, and we were unable to establish diagnostically determining minimal thresholds of the intra-articular CRP and leukocyte levels. Conclusions: This pilot study suggests that either the leukocyte or PMN counts may be associated with a bacterial origin of knee arthritis in children. We plan a larger prospective interventional study in the future to confirm these findings including the investigation of other joint aspirate biomarkers.

Long-term humoral immunogenicity, safety and protective efficacy of inactivated vaccine against reindeer rabies.

The core element of the reindeer rabies eradication strategy is regular application of vaccines to obtain and uphold a vaccination coverage sufficient for the ceasing of rabies virus transmission. This article presents the results of reindeer humoral immunity intensity and duration study after the immunization with two form of inactivated rabies vaccines (adjuvanted liquid vaccine and non-adjuvanted lyophilized vaccine) based on the Shchelkovo-51 rabies virus strain. Efficiency of post-vaccine immunity was assessed by measuring the animal blood serum virus-neutralizing antibody level in a neutralization test. The study determined the efficient rabies vaccine injection dose as equal to 3 ml. A single dose of 3 ml of these vaccines induced stable production of specific neutralizing antibodies in reindeer as early as 7 day after administration, and by 30 days after immunization, it significantly exceeded the minimal threshold level accepted by OIE. Two doses of vaccines administration with an interval of 30 days are required to achieve a strong immunity with the rabies-specific virus-neutralizing antibody titer of more than 0.5 IU/ml for at least 2 years. Our data do not support the benefit of an adjuvanted vaccine for the prevention of rabies in reindeer.

P07.09.A Intra operative mapping and monitoring of the cortico-spinal tracts with neurophysiological assessment in intra axial brain tumor resection

Abstract Background Preserving motor function is a major challenge in surgery for intra axial brain tumors. In the past two decades, rapid developments in neuroscience, have fueled the growth of intraoperative neurophysiologic monitoring and mapping. Neurophysiological motor mapping allows identification with subsequent preservation of functionally viable nervous tissue. Currently, continuous mapping is typically achieved by electrostimulating via connection to a surgical tool, )e.g., suction(, establishing a stimulation threshold for inducing a motor response, and stopping the resection when reaching motor responses at low electrostimulation levels of 2-10 mA. While most authors report the use of monopolar electrostimulation, which tends toward high sensitivity - low specificity, others report the use of bipolar electrostimulation, which tends toward high specificity - low sensitivity results. Here we report an investigation of the differences between monopolar and bipolar electrostimulation for motor mapping, comparing the sensitivity and specificity of the two methods. Material and Methods Gross motor function was evaluated preoperative and 1d postoperative. During the resection, a minimal monopolar electrostimulation threshold was determined, bordering motor tracts. Next, a bipolar probe was used to assess the bipolar electrostimulation threshold at the same location, and a neuro-navigation system was used to mark these locations. The respondent myotomes at each location was documented, as well as the neuromonitoring MEP responses. Postoperatively, the distance between the stimulated marked location, resection borders, and the motor brain structures were assessed. Analysis probed the differences between monopolar and bipolar thresholds in mapping cortical and subcortical motor system and their association with motor neuromonitoring and postoperative motor function. Results A prospective intraoperative analysis was conducted on two patients undergoing resection of intra axial tumors at the authors' institution in January 2021. The resection was performed by all clinical standard procedures. Following the resection, additional stimuli were applied by the bipolar probe, to assess the accuracy of the threshold that was needed to evoke a clinical motor response. We found that the bipolar threshold was higher than the conventional threshold used by the monopolar probe in the borders of the resection. Conclusion Our findings suggest the bipolar stimuli can give more accuracy in determining the motor function of certain anatomical structures which can lead to better results in the maximal safe resections goal and allow neurosurgeons another intra operative tool to achieve the best outcomes for their patients.

The Effect of Core Stabilization Training on Improving Gait and Self-Perceived Function in Patients with Knee Osteoarthritis: A Single-Arm Clinical Trial.

The treatment of patients with knee osteoarthritis is typically focused on the involved lower extremity. There is a gap in the literature concerning the effectiveness of core stabilization training on the treatment of patients with knee osteoarthritis. This investigation aimed to determine whether core stabilization improved the gait and functional ability of patients with knee osteoarthritis. Eighteen participants with knee osteoarthritis completed the six-week core stabilization intervention. Participants completed the gait motion analysis and the Knee Injury and Osteoarthritis Outcome Score to assess self-perceived function, pre- and post-intervention. Gait speed improved (p = 0.006, d = 0.59), while the external knee adduction moment decreased (p = 0.034, d = −0.90). Moreover, self-reported function improved (p < 0.001, d = 1.26). The gait speed and external knee adduction moment changes met minimal detectable change thresholds, while gait speed also met the minimal clinically important difference. A six-week core stabilization program can thus improve gait speed and reduce the external knee adduction moment, which is tied to disease progression. Increased functional scores post-intervention indicate an important clinical improvement. Core stabilization training is a safe and potentially effective treatment option for this population.

Impact of Serum P Levels on Pregnancy Outcome in ART

Background: The role of mid luteal progesterone (P) levels has gained interest in the last years. Low serum P levels significantly decrease the chances of ongoing pregnancy, mainly in artificial cycles for embryo transfer. Our prospective studies have found that patients with low serum P levels on the day of ET had a significantly lower live birth rate, either when using own or donated oocytes. Aim: To summarize the current evidence about the impact of serum P levels on pregnancy outcome in ART; and the proposed strategies to overcome this situation. To differentiate the PK and PD of the different routes of exogenous P and how this influence on the interpretation of results. Method: Review of the literature. The research leaded by the lecturer will be presented. Results: In artificial cycles, there is a minimum threshold of serum P levels that needs to be reached. Approximately 30% of women show inadequate levels of serum P after receiving the standard dose of vaginal P. Individualization of luteal phase support by routinely measuring P levels, allows to detect which patients need raised P in order to optimise their outcome. Addition of extra doses of P seems to overcome this detrimental effect, ideally associating other routes of P. Conclusion: Low P levels on the day of ET decrease live birth rates. If outcomes are to be optimised, a minimal threshold of serum P values on the day of ET must be reached. Personalization of luteal phase support is advisable to optimize the results.

Social Distancing Using YOLOv3 Model

Social isolation has been found to be a successful strategy for preventing the coronavirus from spreading around the world. In order to stop the virus from spreading as possible, the system is designed to analyses social distance by measuring the space between individuals. To lessen the impact of the epidemic, this technology uses input from camera frames to calculate the distance between people. By analyzing a video stream collected from a security camera, this is accomplished. The video is adjusted for a higher perspective and sent in to the prepared item discovery model YOLOv3 as input. The Common Object in Context is used to train the YOLOv3 model (COCO). A previously shot video supported the suggested system. The system's results and consequences demonstrate how to assess the space between different people and decide whether rules are being broken. People are addressed by a red jumping box if the distance is below the minimal threshold value and a green jumping box otherwise. This technique can be improved to recognize social exclusion in a real time setting.

Very Low-Level Transcranial Photobiomodulation for Major Depressive Disorder: The ELATED-3 Multicenter, Randomized, Sham-Controlled Trial.

Background: Transcranial photobiomodulation (t-PBM) with near-infrared (NIR) light might represent a treatment for major depressive disorder (MDD). However, the dosimetry of administered t-PBM varies widely. We tested the efficacy of t-PBM with low irradiance, low energy per session, and low number of sessions in individuals with MDD.Methods: A 2-site, double-blind, sham-controlled study was conducted of adjunct t-PBM NIR (830 nm; continuous wave; 35.8 cm2 treatment area; 54.8 mW/cm2 irradiance; 65.8 J/cm2 fluence, 20 min/session; ~2 W total power; 2.3 kJ total energy per session), delivered to the prefrontal cortex, bilaterally, twice a week for 6 weeks, in subjects diagnosed with MDD per the DSM-IV criteria. Subjects were recruited between August 2016 and May 2018. A sequential parallel comparison design was used: 18 nonresponders to sham in phase 1 (6 weeks) were re-randomized in phase 2. The primary outcome was reduction in depression severity (Hamilton Depression Rating Scale [HDRS-17] and Quick Inventory of Depressive Symptomatology-Clinician Rating [QIDS-C] scores) from baseline. Statistical analyses used R package SPCDAnalyze2, including all subjects with ≥ 1 post-randomization evaluation.Results: Of the 54 subjects recruited, we included 49 MDD subjects in the analysis (71% female, mean ± SD age 40.8 ± 16.1 years). There were no significant differences between t-PBM and sham with respect to the change in HDRS-17 (t = -0.319, P = .751) or QIDS-C (t = -0.499, P = .620) scores. The sham effect was reasonably low.Conclusions: Mostly uncontrolled studies suggest the efficacy of t-PBM for MDD; however, its optimal dose is still to be defined. A minimal dose threshold is likely necessary, similarly to other neuromodulation techniques in MDD (electroconvulsive therapy, transcranial magnetic stimulation). We established a threshold of inefficacy of t-PBM for MDD, based on combined low irradiance, low energy per session, and low number of sessions.Trial Registration: ClinicalTrials.gov identifier: NCT02959307.

Testis Cancer Care in North Carolina: Implications for Real-World Evidence and Cancer Surveillance.

Contemporary testis cancer management requires fastidious adherence to clinical guidelines and care principles, especially for those pursuing active surveillance (AS). However, real-world testis cancer care remains largely undescribed. Accordingly, we sought to assess the rigor of evaluation and monitoring among men with testis cancer. Using North Carolina Central Cancer Registry data linked to insurance claims, we selected adult males diagnosed with primary testis cancer from 2003 to 2013. After identifying demographics, care setting, histology, stage, and index management, we evaluated the receipt of tumor markers, imaging, and clinic visits during initial evaluation and subsequent monitoring with respect to contemporaneous clinical guidelines. Care patterns were compared using chi-squared testing and multivariable logistic regression. Of 2526 men with primary testis cancer, we assembled a cohort of 487 with seminoma (59.3%) or nonseminoma (40.7%), losing most to a lack of insurance or continuous coverage. The cohort was predominantly white (92.4%) and had stage I disease (87.9%). Overall, 18.9% had complete tumor markers, staging imaging, and visits with 2 relevant specialists as recommended during their initial evaluation. For subsequent monitoring, 17.5% of patients with seminoma on active surveillance met minimal thresholds for recommended testing and follow-up during the first year vs. 21.9% and 34.9% of patients with seminoma treated with adjuvant radiation and chemotherapy, respectively. For nonseminoma, 10.1% of men on active surveillance met the minimal thresholds for recommended monitoring compared with 60.4% and 62.0% of those treated with surgery and chemotherapy, respectively. Recommended monitoring also differed by academic vs. community setting and receipt of recommended evaluation (P < .05). From real-world data, the evaluation and monitoring of patients with testis cancer appears substandard. Ongoing data and quality gaps highlight potential challenges with generating real-world evidence and ensuring adequate surveillance in this population.

Abnormal urinary loss of vitamin C in diabetes: prevalence and clinical characteristics of a vitamin C renal leak

Diabetes is associated with low plasma vitamin C concentrations. We investigated the contribution of dysregulated vitamin C renal physiology, its prevalence, and associated clinical characteristics. An essential prerequisite was determination of normal vitamin C renal threshold, the plasma concentration at which vitamin C first appears in urine. Using data from 17 healthy participants who underwent vitamin C depletion-repletion studies with a vitamin C dose range of 15-1250mg daily, renal threshold was estimated using physiology-based pharmacokinetics modeling. Applying renal threshold 95% CIs, we estimated the minimal elimination threshold, the plasma concentration below which no vitamin C was expected in urine of healthy people. Renal leak was defined as abnormal presence of vitamin C in urine with plasma concentrations below the minimal elimination threshold. Criteria were tested in a cross-sectional cohort study of individuals with diabetes (82) and nondiabetic controls (80) using matched plasma and urine samples. Vitamin C renal thresholds in healthy men and women were [mean (SD)] 48.5 (5.2) µM and 58.3 (7.5) µM, respectively. Compared with nondiabetic controls, participants with diabetes had significantly higher prevalence of vitamin C renal leak (9% compared with 33%; OR: 5.07; 95% CI: 1.97, 14.83; P<0.001) and 30% lower mean plasma vitamin C concentrations (53.1 µM compared with 40.9 µM, P<0.001). Fasting plasma glucose, glycosylated hemoglobin A1c, BMI, micro/macrovascular complications, and protein/creatinine ratio were predictive of vitamin C renal leak. Increased prevalence of vitamin C renal leak in diabetes is associated with reduced plasma vitamin C concentrations. Glycemic control, microvascular complications, obesity, and proteinuria are predictive of renal leak.

Urethane Improves the Response of Auditory Neurons to Tone.

Urethane has little effect on nervous system and is often used in neuroscience studies. However, the effect of urethane in neurons is not thoroughly clear. In this study, we investigated changes in neuron responses to tones in inferior colliculus during urethane anesthesia. As urethane was metabolized, the best and characteristic frequencies did not obviously change, but the minimal threshold (MT) remained relatively stable or was elevated. The frequency tuning bandwidth at 60 dB SPL (BW60dBSPL) remained unchanged or decreased, and the average evoked spike of effective frequencies at 60 dB SPL (ES60dBSPL) gradually decreased. Although the average evoked spike of effective frequencies at a tone intensity of 20 dB SPL above MT (ES20dBSPLaboveMT) decreased, the frequency tuning bandwidth at a tone intensity of 20 dB SPL above MT (BW20dBSPLaboveMT) did not change. In addition, the changes in MT, ES60dBSPL, BW60dBSPL, and ES20dBSPLaboveMT increased with the MT in pre-anesthesia awake state (MTpre−anesthesiaawake). In some neurons, the MT was lower, BW60dBSPL was broader, and ES60dBSPL and ES20dBSPLaboveMT were higher in urethane anesthesia state than in pre-anesthesia awake state. During anesthesia, the inhibitory effect of urethane reduced the ES20dBSPLaboveMT, but did not change the MT, characteristic frequency, or BW20dBSPLaboveMT. In the recording session with the strongest neuron response, the first spike latency did not decrease, and the spontaneous spike did not increase. Therefore, we conclude that urethane can reduce/not change the MT, increase the evoked spike, or broaden/not change the frequency tuning range, and eventually improve the response of auditory neurons to tone with or without “pushing down” the tonal receptive field in thresholding model. The improved effect increases with the MTpre−anesthesiaawake of neurons. The changes induced by the inhibitory and improved effects of urethane abide by similar regularities, but the change directions are contrary. The improvement mechanism may be likely due to the increase in the ratio of excitatory/inhibitory postsynaptic inputs to neurons.

Scaling Laws in Aeolian Sand Transport Under Low Sand Availability

AbstractPrevious studies of wind‐blown sand have considered either fully erodible or non‐erodible soils, but the transport over sparsely sand‐covered soils is still poorly understood. The quantitative modeling of this transport is important for parameterizing Aeolian processes under low sand availability. Here we show, by means of numerical simulations, that the sand transport rate Q scales with the wind shear velocity u∗ as , where u∗t is the minimal threshold u∗ for sustained transport, d is particle size, g is gravity and ρf is air density, while u∗t and the empirical parameters a and b depend on the sand cover thickness. Our model explains the transition from the quadratic to cubic scaling of Q with u∗ as soil conditions change from fully erodible to rigid and provides constraints for modeling Aeolian transport under low sand availability.

Phenology Patterns and Postfire Vegetation Regeneration in the Chiquitania Region of Bolivia Using Sentinel-2

The natural regeneration of ecosystems impacted by fires is a high priority in Bolivia, and represents one of the country’s greatest environmental challenges. With the abundance of spatial data and access to improved technologies, it is critical to provide an effective method of analysis to evaluate changes in land use in the face of the global need to understand the dynamics of vegetation in regeneration processes. In this context, we evaluated the dynamics of natural regeneration through phenological patterns by measuring the maximal and minimal spectral thresholds at four fire-impacted sites in Chiquitania in 2019 and 2020, and compared them with unburned areas using harmonic fitted values of the Normalized Difference Vegetation Index (NDVI) and the Normalized Burn Ratio (NBR). We used two-way ANOVA test to evaluate the significant differences in the values of the profiles of NDVI and NBR indices. We quantified severity at the four study sites using the dNBR obtained from the difference between pre- and postfire NBR. Additionally, we selected 66 sampling sites to apply the Composite Burn Index (CBI) methodology. Our results indicate that NBR is the most reliable index for interannual comparisons and determining changes in the phenological pattern, which allow for the detection of postfire regeneration. Fire severity levels based on dNBR and CBI indices are reliable methodologies that allow for determining the severity and dynamics of changes in postfire regeneration levels in forested and nonforested areas.

Minimal energy thresholds for sustained turbulent bands in channel flow

In this work, nonlinear variational optimization is used for obtaining minimal seeds for the formation of turbulent bands in channel flow. Using nonlinear optimization together with energy bisection, we have found that the minimal energy threshold for obtaining spatially patterned turbulence scales with$Re^{-8.5}$for$Re&gt;1000$. The minimal seed, which is different to that found in a much smaller domain, is characterized by a spot-like structure surrounded by a low-amplitude large-scale quadrupolar flow filling the whole domain. This minimal-energy perturbation of the laminar flow has dominant wavelengths close to$4$in the streamwise direction and$1$in the spanwise direction, and is characterized by a spatial localization increasing with the Reynolds number. At$Re \lesssim 1200$, the minimal seed evolves in time, creating an isolated oblique band, whereas for$Re\gtrsim 1200$, a quasi-spanwise-symmetric evolution is observed, giving rise to two distinct bands. A similar evolution is found also at low$Re$for non-minimal optimal perturbations. This highlights two different mechanisms of formation of turbulent bands in channel flow, depending on the Reynolds number and initial energy of the perturbation. The selection of one of these two mechanisms appears to be dependent on the probability of decay of the newly created stripe, which increases with time, but decreases with the Reynolds number.

Therapeutic drug monitoring in dermatology: the way towards dose optimization of secukinumab in chronic plaque psoriasis.

SummaryBackgroundDespite the favourable efficacy profile of secukinumab, clinicians encounter varying clinical responses among patients potentially associated with under‐ and overdosing. As biologics are expensive, their rational use is crucial and evident. Therapeutic drug monitoring could guide clinicians in making decisions about treatment modifications.AimIn this multicentre, prospective study, we aimed to develop and validate a secukinumab immunoassay and searched for the therapeutic window in patients with psoriasis.MethodsWe determined secukinumab concentrations at trough in sera from 78 patients with psoriasis at multiple timepoints (Weeks 12, 24, 36, 48 and 52; after Week 52, measurements could be taken at an additional three timepoints) during maintenance phase, using an in‐house secukinumab immunoassay consisting of a combination of MA‐SEC66A2 as capture antibody and MA‐SEC67A9, conjugated to horseradish peroxidase, as detecting antibody. At each hospital visit, disease severity was assessed using the Psoriasis Area and Severity Index (PASI).ResultsAfter quantification, 121 serum samples were included for dose–response analysis. Based on a linear mixed‐effects model, secukinumab trough concentrations were found to decrease with increasing body mass index (BMI). Based on receiver operating characteristic (ROC) analysis, we concluded that the minimal effective secukinumab threshold was 39.1 mg/L in steady state, and that this was associated with a 92.7% probability of having an optimal clinical response (PASI ≤ 2 or reduction in PASI of ≥ 90%).ConclusionsMonitoring and targeting a secukinumab trough concentration of 39.1 mg/L may be a viable treatment option in suboptimal responders. In patients with higher BMI, weight‐based dosing may be needed in order to prevent underdosing.

Continuous but not pulsed low-dose fetal betamethasone exposures extend the durability of antenatal steroid therapy.

Antenatal steroid (ANS) therapy is the standard care for women at imminent risk of preterm labor. Despite extensive and long-standing use, 40%-50% of babies exposed antenatally to steroids do not derive benefit; remaining undelivered 7 days or more after ANS treatment is associated with a lack of treatment benefit and increased risk of harm. We used a pregnant sheep model to evaluate the impact of continuous versus pulsed ANS treatments on fetal lung maturation at an extended, 8-day treatment to delivery interval. Continuous low-dose ANS treatments for more than 72 h in duration improved fetal lung maturation at 8 days after treatment initiation. If fetal ANS exposure was interrupted, the beneficial ANS effect was lost. Truncated treatments, including that simulating the current clinical treatment regimen, did not improve lung function. Variable fetal lung maturation was correlated to the amount of saturated phosphatidylcholine present in the lung fluid. These data demonstrate that 1) the durability of ANS therapy may be enhanced by employing an extended, low-dose treatment regimen by reducing total dose and 2) interrupting the continuity of fetal exposure by allowing it to fall below a minimal threshold was associated with comparably poor functional maturation of the preterm ovine lung.

The impact of the length of total and intravenous systemic antibiotic therapy for the remission of diabetic foot infections

ObjectiveWe investigated the impact of the total length of systemic antibiotic therapy (ABT) and its initial intravenous (IV) part on clinical failure (CF) and microbiological failure (MF) in diabetic foot infections (DFIs). MethodsIn this single-center, retrospective, unmatched case-control study, we included DFI episodes treated with a combined surgical-antibiotic approach. ResultsWe included 721 DFI episodes, 537 with osteomyelitis (DFO). CF occurred in 191 (26.5%) and MF in 42 (5.8%) episodes. Multivariate Cox regression analysis showed that a short ABT of 8–21 days (hazard ratio [HR] 0.4; 95% CI 0.2–0.7) was inversely associated with CF. This was also applicable for IV ABT with relatively short durations of 2–7 days (HR 0.5; 95% CI 0.3–0.8) or 8–14 days (HR 0.6; 95% CI 0.4–0.9). We failed to detect a minimal threshold of total or IV ABT predictive for CF or MF. ConclusionsCompared with total ABT of more than 84 days and IV therapy of more than 14 days, shorter total and IV ABT yielded no enhanced risk of CF or MF. Considering the “bias by indication” that is inherent to retrospective DFI studies, the best study design concerning the duration of ABT would be a stratified, prospective randomized trial, which is currently under way in our medical center.

Minimal energy thresholds for triggering in the Rijke tube: the effect of the time delay

Triggering is the process by which a linearly stable thermoacoustic system can reach self-sustained oscillations. This nonlinear phenomenon is activated only for sufficiently large amplitudes of perturbations to the equilibrium state. In this work, using a nonlinear variational optimisation method coupled with energy bisection, we compute the minimal thresholds for triggering in the Rijke tube. In particular, extending previous works, we take into account the effect of the time delay by optimising not only the perturbations at initial time, but also the velocity at the hot-wire position in the time-delay interval. We found that, for sufficiently large time delays, the nonlinearity linked to the delayed flow velocity bears a strong potential for energy growth, leading to transient amplifications of the energy reaching ${O}(10^{2})$, two orders of magnitude larger than those reported in previous studies. Notably, the gain increases with the time delay, but decreases with the initial energy of the perturbation, thus reaching very high values close to the triggering threshold of the system. The minimal energy for triggering self-sustained oscillations achieves energy values as low as ${O}(10^{-4})$, two orders of magnitude smaller than previous estimates. This indicates that, for thermoacoustic systems characterised by a non-negligible time delay, taking into account the effect of the time-delayed variables, as well as the system nonlinearity, is crucial for correctly evaluating the triggering energy thresholds.

The Minimal Subcortical Electronic Threshold Predicts the Motor Deficit and Survivals in Non-Awake Surgery for Gliomas Involving the Motor Pathway.

PurposeDirect subcortical motor mapping is the golden criterion to detect and monitor the motor pathway during glioma surgery. Minimal subcortical monopolar threshold (MSCMT) means the minimal distance away from the motor pathway and is critical to decide to continue or interrupt glioma resection. However, the optimal cutoff value of MSCMT for glioma resection in non-awake patients has not been reported discreetly. In this study, we try to establish the safe cutoff value of MSCMT for glioma resection and analyzed its relationship with postoperative motor deficit and long-term survivals.MethodsWe designed this prospective study with high-frequency electronic stimulus method. The cutoff MSCMT of postoperative motor deficits was statistically calculated by receiver operating characteristic (ROC) curve, and its relationship with motor deficit and survivals was analyzed by logistic and Cox regression, respectively.ResultsThe cutoff MSCMT to predict motor deficit after surgery was 3.9 mA on day 1, 3.7 mA on day 7, 5.2 mA at 3 months, and 5.2 mA at 6 months. MSCMT ≤3.9 mA and MSCMT ≤5.2 mA independently predicted postoperative motor deficits at four times after surgery (P < 0.05) but had no effect on the removal degree of tumor (P > 0.05). In high-grade gliomas, MSCMT ≤3.9 mA independently predicted shorter progression-free survival [odds ratio (OR) = 3.381 (1.416–8.076), P = 0.006] and overall survival [OR = 3.651 (1.336–9.977), P = 0.012]. Power model has the best fitness for paired monopolar and bipolar high-frequency thresholds.ConclusionsThis study showed strong cause–effect relation between MSCMT and postoperative motor deficit and prognoses. The cutoff MSCMT was dug out to avoid postoperative motor deficit. Further studies are needed to establish the results above.

Peritoneal dialysis adequacy: a paradigm shift.

For the past 30 years, nephrologists have focused on a single minimal threshold of Kt/Vurea to determine the adequacy of peritoneal dialysis (PD). To date, there is no evidence that shows Kt/Vurea to be a good surrogate measure of uremic symptom control or nutritional state in patients on PD. Volume of distribution (Vurea) generally is considered equivalent to total body water (TBW). Yet, accurate determination of TBW is difficult. The most recent International Society for Peritoneal Dialysis practice recommendations on prescribing high-quality PD emphasized incorporation of multiple measures rather than the single value of Kt/Vurea. These measures include shared decision-making between the patient and the care team and assessment of health-related quality of life, burden of uremic symptoms, presence of residual kidney function, volume status, and biochemical measures including serum potassium and bicarbonate levels. In some cases, PD prescriptions can be tailored to the patient priorities and goals of care, such as in frail and pediatric patients. Overall, there has been a paradigm shift in providing high-quality care to PD patients. Instead of focusing on small solute clearance in the form of Kt/Vurea, nephrologists are encouraged to use a more comprehensive assessment of the patient as a whole.