Temporary Instability Research Articles

Flutter performance of a suspension bridge equipped with separated oblique stabilizers covering different span lengths

Vertical stabilizers have been proved to be effective for flutter suppression of long-span bridges, while their self-stability under strong winds should be taken seriously. This study takes a steel truss stiffening girder as an example, and effects of oblique stabilizers on the flutter performance are investigated. After discussing the wind environment above the bridge site, the flutter derivatives of girder extracted by numerical simulations are given to compute the critical flutter wind speed by a bimodal coupled flutter analysis method. Subsequently, with considering the lateral self-excited force, the flutter performance is accurately evaluated by performing complex modal characteristics based on a full-order modal flutter analysis method. After setting different types of stabilizers with different covering lengths, improvement of the flutter performance is discussed. The results show that the flutter performance is related to multiple modes. Temporary flutter instability of a modal branch may be caused due to the curve-veering phenomenon among similar modes. Thus, the critical flutter wind speed may be overestimated by bimodal-coupled flutter analyses. At negative angles of attack, the set of oblique stabilizers are flutter favorable by improving the temporary flutter instability. Setting partial stabilizers around the mid-span is more flutter favorable than covering the entire girder.

How to Stabilize the Current of Efficient Inverted Flexible Perovskite Solar Cells at the Maximum Power Point.

Inverted flexible perovskite cells (fPSCs) have attracted much attention for their high efficiency and power per weight. Still, the steady-state output is one of the critical factors for their commercialization. In this paper, it is found that the steady-state current of inverted fPSCs based on nickel oxide nanoparticles (n-NiOx) continuously decreases under light illumination. Conversely, those based on magnetron-sputtered NiOx (sp-NiOx) exhibit the opposite result. Based on visualization of ion migration in the photoluminescence (PL) imaging microscopy tests, the discrepancies in the buried surfaces lead to the differences in ion migration in perovskite films, which triggers the temporary instability of the output current of devices during operation. The DFT theoretical calculation and experimental results reveal that NiOx films with different contents of Ni vacancies can modulate the crystallization of the perovskite films on the NiOx surfaces. Tuning the crystallization of the perovskite films is essential to stabilize the output current of fPSCs at a steady state. To demonstrate that, capsaicin is doped into the perovskite solutions to improve the quality of the perovskite buried interface. Finally, the corresponding fPSCs exhibit outstanding efficiency and stability during operation. These results provide valuable scientific guidance for fabricating fPSCs with stable operation under illumination conditions.

Traction Spurs in the Lumbar Spine: A Historical Overview and Future Perspectives.

Numerous studies have explored the connection between lumbar osteophytes, their pathophysiology, and instability since Macnab's 1971 report on traction spurs as an indicator of lumbar instability. This study provides a narrative historical overview of traction spurs, a classic finding that suggests lumbar instability. It summarizes the causes of anterior lumbar vertebral osteophytes, the relationship between traction spurs and lumbar spinal instability, and the clinical significance of traction spurs. Vertebral osteophytes are grouped into two categories, namely, traction spurs or claw spurs, which represent different stages of the same pathological process. Traction spurs are indicative of instability and occur in the early stage of disc degeneration, characterized by temporary dysfunction or instability. Traction spur formation following fusion surgery can predict union or nonunion, and it serves as an indicator of preoperative and postoperative segmental instability. The relationship between traction spurs and radiographic instability, as well as their association with imaging findings such as CT and MRI, has been clarified. Additionally, finite element analysis and mechanical testing have been used to investigate the significance of traction spurs. However, further research is needed to verify that traction spurs are an accurate indicator of pre- and postoperative lumbar instability.

The Long-term Spectral Changes of Eta Carinae: Are they Caused by a Dissipating Occulter as Indicated by cmfgen Models?

Abstract Eta Carinae (η Car) exhibits a unique set of P Cygni profiles with both broad and narrow components. Over many decades, the spectrum has changed—there has been an increase in observed continuum fluxes and a decrease in Fe ii and H i emission-line equivalent widths. The spectrum is evolving toward that of a P Cygni star such as P Cygni itself and HDE 316285. The spectral evolution has been attributed to intrinsic variations such as a decrease in the mass-loss rate of the primary star or differential evolution in a latitudinal-dependent stellar wind. However, intrinsic wind changes conflict with three observational results: the steady long-term bolometric luminosity; the repeating X-ray light curve over the binary period; and the constancy of the dust-scattered spectrum from the Homunculus. We extend previous work that showed a secular strengthening of P Cygni absorptions by adding more orbital cycles to overcome temporary instabilities and by examining more atomic transitions. cmfgen modeling of the primary wind shows that a time-decreasing mass-loss rate is not the best explanation for the observations. However, models with a small dissipating absorber in our line of sight can explain both the increase in brightness and changes in the emission and P Cygni absorption profiles. If the spectral evolution is caused by the dissipating circumstellar medium, and not by intrinsic changes in the binary, the dynamical timescale to recover from the Great Eruption is much less than a century, different from previous suggestions.

Temporary Stability of Composite Thin-Film Resistive Structures

The processes occurring in the structure of thin films leading to a change in the resistance of a thin-film resistor over time are investigated. The addition of a thin film to the resistor with the opposite direction of the resistance "drift" allows minimizing the effect of aging processes on the total resistance of the composite resistor. Various design options are presented that provide an opportunity to compensate for the temporary instability of a thin-film resistor, including one close to zero. Their advantages and disadvantages are shown.

Generation of gravitational waves in dynamical Chern-Simons gravity

We investigate gravitational waves (GWs) generated in a two-field inflationary model with a noncanonical kinetic term, in which the gravitational Chern-Simons term is coupled to a heavy dynamical field. In such a model, primordial GWs experience a period of resonant amplification for some modes. In addition, isocurvature perturbations suffer from a temporary tachyonic instability due to an effective negative mass, which source curvature perturbations, resulting in large induced GWs. These two stochastic gravitational wave backgrounds correspond to different frequency bands, which are expected to be detected by future GW detectors such as SKA, LISA, and Taiji.

Native Study of the Behaviour of Magnetite Nanoparticles for Hyperthermia Treatment during the Initial Moments of Intravenous Administration.

Magnetic nanoparticles (MNPs) present outstanding properties making them suitable as therapeutic agents for hyperthermia treatments. Since the main safety concerns of MNPs are represented by their inherent instability in a biological medium, strategies to both achieve long-term stability and monitor hazardous MNP degradation are needed. We combined a dynamic approach relying on flow field flow fractionation (FFF)-multidetection with conventional techniques to explore frame-by-frame changes of MNPs injected in simulated biological medium, hypothesize the interaction mechanism they are subject to when surrounded by a saline, protein-rich environment, and understand their behaviour at the most critical point of intravenous administration. In the first moments of MNPs administration in the patient, MNPs change their surrounding from a favorable to an unfavorable medium, i.e., a complex biological fluid such as blood; the particles evolve from a synthetic identity to a biological identity, a transition that needs to be carefully monitored. The dynamic approach presented herein represents an optimal alternative to conventional batch techniques that can monitor only size, shape, surface charge, and aggregation phenomena as an averaged information, given that they cannot resolve different populations present in the sample and cannot give accurate information about the evolution or temporary instability of MNPs. The designed FFF method equipped with a multidetection system enabled the separation of the particle populations providing selective information on their morphological evolution and on nanoparticle-proteins interaction in the very first steps of infusion. Results showed that in a dynamic biological setting and following interaction with serum albumin, PP-MNPs retain their colloidal properties, supporting their safety profile for intravenous administration.

The diagnosis of satellite flywheel bearing cage fault based on two-step clustering of multiple acoustic parameters

As the critical component of satellite flywheels, bearings should be tested and selected on the ground before the flight. Aiming at the condition assessment requirements of flywheel bearing cage in the ground test, this paper proposes a non-contact diagnosis method based on the acoustic signal. First, the acoustic signals of the flywheel bearing cage under normal, rubbing, and uneven lubrication conditions are acquired, and it is found that the traditional envelope demodulation method is difficult to distinguish these states effectively. Therefore, an idea based on multi-parameter clustering fusion diagnosis is proposed. Then, the limitations of the direct clustering method to identify and classify the types of cage faults are revealed. Finally, a new diagnosis and identification method based on two-step clustering is proposed to improve the diagnosis capability. The test results show that cage temporary instability and rubbing fault can be diagnosed and identified effectively by the proposed method.

Pilot investigation on biostability of drinking water distribution systems under water source switching.

Water quality deterioration of drinking water distribution systems (DWDSs) caused by water source switching has been reported previously. However, systematic investigation of the biostability of DWDS under water source switching is limited. Aged pipes, including three commonly used pipe materials dug out from a practical DWDS, were used to systematically investigate the biofilm stability mechanism of DWDS under water source switching to quality-improved water. An increase in adenosine triphosphate (ATP) concentration in the bulk water during the initial stage of the switching period was observed, indicating the risk of biofilm release through aged pipe surfaces after water source switching. Sloughing of biofilms might contribute to temporary instability. From day 35, the ATP concentration in the polyethylene (PE) and plastic stainless steel composite (PS) pipes were maintained at approximately 2.40 and 2.56 ng/L, respectively. In contrast, the ATP concentration in the ductile iron (DI) pipes was higher, at approximately 3.43 ng/L from day 42. The water quality variation could cause areas of the biofilm to slough and reduce the biomass of biofilm, causing partial alteration of the microbial community. 16S rRNA gene amplicon sequencing-based functional prediction revealed that the biofilm could increase the abundance of chlorine-resistant bacteria attributed to the increase in Pseudomonas and Methylobacterium after switching to quality-improved water. Moreover, the profiles of specific pathways linked to human diseases, antibiotic resistance, and antibiotic biosynthesis revealed that the safety of the biofilm could improve after switching to quality-improved water. KEY POINTS: • The PE and PS biofilm showed improved resistance to water quality perturbation. • Greater number of Methylobacterium was found in the biofilm after water source switching. • 3.16S gene-based metagenomics prediction revealed that the safety of the biofilm under water source switching.

The change in glycaemic control immediately after COVID-19 vaccination in people with type 1 diabetes.

Evidence suggests that some people with type 1 diabetes mellitus (T1DM) experience temporary instability of blood glucose (BG) levels after COVID-19 vaccination. We aimed to assess this objectively. We examined the interstitial glucose profile of 97 consecutive adults (age≥18years) with T1DM using the FreeStyle Libre® flash glucose monitor in the periods immediately before and after their first COVID-19 vaccination. The primary outcome measure was percentage (%) interstitial glucose readings within the target range 3.9-10mmol/L for 7days prior to the vaccination and the 7days after the vaccination. Data are mean±standard error. There was a significant decrease in the % interstitial glucose on target (3.9-10.0) for the 7days following vaccination (mean 52.2%±2.0%) versus pre-COVID-19 vaccination (mean 55.0%±2.0%) (p=0.030). 58% of individuals with T1DM showed a reduction in the 'time in target range' in the week after vaccination. 30% showed a decrease of time within the target range of over 10%, and 10% showed a decrease in time within target range of over 20%. The change in interstitial glucose proportion on target in the week following vaccination was most pronounced for people taking metformin/dapagliflozin+basal bolus insulin (change -7.6%) and for people with HbA1c below the median (change -5.7%). In T1DM, we have shown that initial COVID-19 vaccination can cause temporary perturbation of interstitial glucose, with this effect more pronounced in people talking oral hypoglycaemic medication plus insulin, and when HbA1c is lower.

The Effects of High-Intensity Interval Training (HIIT) on Fall Risk Factors in Healthy Older Adults: A Systematic Review.

High-intensity interval training (HIIT) improves functional capacity, muscle power and physical performance in older adults with and without comorbidities. The aim of this study was to explore the effectiveness of HIIT as a method for reducing major fall risk factors (balance, muscle strength and physical activity) in older adults. A systematic literature search was conducted following the PRISMA guidelines. A computerized search was conducted using electronic databases (PubMed, CINAHL, Cochrane Library, APA PsycInfo, Web of Science, Scopus, PEDro, and AgeLine) published up to July 2021. Eleven papers (9 studies) of moderate quality (mean of 5.5 in Pedro scale) involving 328 healthy older adults met the inclusion criteria. Studies were characterized by high heterogeneity in terms of methodology, HIIT modality and protocol, subject characteristics, and outcome measures. Results indicate that HIIT cannot be recommended as a single modality for fall prevention in older adults due to insufficient data and no consensus among the studies. HIIT appears to be a safe and well-tolerated supplement to proven fall prevention programs, due to its effects on lower limb strength reflected in functional performance tests, and on dynamic balance and subjective balance perception. However, caution is warranted following HIIT, especially after the first session, due to possible temporary instability.

Analysis of continuous glucose tracking data in people with type 1 diabetes after COVID-19 vaccination reveals unexpected link between immune and metabolic response, augmented by adjunctive oral medication.

IntroductionThe COVID‐19 vaccination programme is under way worldwide. Anecdotal evidence is increasing that some people with type 1 diabetes mellitus (T1DM) experience temporary instability of blood glucose (BG) levels post‐vaccination which normally settles within 2‐3 days. We report an analysis of BG profiles of 20 individuals before/after vaccination.MethodsWe examined the BG profile of 20 consecutive adults (18 years of age or more) with T1DM using the FreeStyle Libre flash glucose monitor in the period immediately before and after COVID‐19 vaccination. The primary outcome measure was percentage (%) BG readings in the designated target range 3.9‐10 mmmol/L as reported on the LibreView portal for 7 days prior to the vaccination (week −1) and the 7 days after the vaccination (week +1).ResultsThere was a significant decrease in the %BG on target following the COVID‐vaccination for the 7 days following vaccination (mean 45.2% ± SE 4.2%) vs pre‐COVID‐19 vaccination (mean 52.6% ± SE 4.5%). This was mirrored by an increase in the proportion of readings in other BG categories 10.1%‐13.9%/≥14%. There was no significant change in BG variability in the 7days post‐COVID‐19 vaccination. This change in BG proportion on target in the week following vaccination was most pronounced for people taking Metformin/Dapagliflozin+basal‐bolus insulin (−23%) vs no oral hypoglycaemic agents (−4%), and median age <53 vs ≥53 years (greater reduction in %BG in target for older individuals (−18% vs −9%)).ConclusionIn T1DM, we have shown that COVID‐19 vaccination can cause temporary perturbation of BG, with this effect more pronounced in patients talking oral hypoglycaemic medication plus insulin, and in older individuals. This may also have consequences for patients with T2DM who are currently not supported by flash glucose monitoring.

Новые подходы к лечению детей с посттравматическими контрактурами локтевого сустава

Abstract. Introduction Post-traumatic elbow contracture is a severe disabling condition of childhood that interferes with both physical and psychic aspects for the child. A high rate of poor results encourages surgeons seek for better surgical treatments. Current diagnostic modalities were practical to get the clinical picture of the contracture mechanogenesis and determine the treatment strategy. The goal of the study was to review long-term results of new surgical techniques developed for post-traumatic elbow contractures in children. Material and methods The inpatient records of 102 pediatric patients with post-traumatic elbow contractures operated on with the technique offered were reviewed. All patients underwent conventional radiological, ultrasound and MSCT examinations. Results Based on the pathobiomechanics of the injured elbow a mobilization technique was developed to ensure complete bone realignment, relieve pain and allow early exercises for the joint. Postoperative lavage of the joint cavity, intra-articular administration of corticosteroids and polyvalent enzymes in the early postoperative period facilitated improved long-term outcomes of elbow contractures. All patients reported good results. Discussion Tenotomies of the lateral ligaments can be added to arthrotomy and reconstruction of articular surfaces for temporary instability of the joint to restore movement in the elbow joint in severe cases. Post-traumatic elbow contractures are accompanied by impaired biomechanics. MSCT and 3D reconstruction of bone structures is the gold standard in the diagnosis of post-traumatic elbow contractures. Conclusion Bone impingements are to be addressed and an extended mobilization of the capsular ligamentous complex be provided for complete movement recovery through partial elbow instability to be temporarily ensured. Prolonged lavage of the elbow joint can be used to prevent adhesions and allow early elbow exercises and provide improved outcomes.

Treatment of Renal Artery Perforation with Covered Stent after Percutaneous Biopsy of Pancreatic Head

In a 67-year-old female patient with upper abdominal pain, computed tomography showed a partly calcified swelling of the pancreatic head and wall thickening of the duodenum. Inpatient physical examination findings were normal. Laboratory showed increased pancreatic enzymes (amylase 210 U/l [Standard range: 28-100 U/l], lipase 2115 U/l [Standard range: 23-300 U/l]) and inflammation values (CRP 11.7 mg/l [Standard range: < 5.0 mg/l]), otherwise largely normal laboratory parameters. In the esophago-gastro-duodenoscopy, biopsy of swollen, partly stenosing mucous membrane areas in the duodenum was performed. Histology revealed partial erosive duodenitis, no evidence of a malignant tumor. If chronic calcifying pancreatitis was suspected, a sonographically guided percutaneous biopsy of the pancreatic head was performed to exclude a tumor. Post-biopsy, the patient developed abdominal pain and temporary circulatory instability with nausea/vomiting and a drop in Hb to 7.5 g/dl [Standard range: 12.3-15.3 g/dl]. The sonographic suspicion of a retroperitoneal hematoma was confirmed by computed tomography. The cause was a haemorrhage from a renal artery perforation on the right side, which could be stopped by immediate angiographic intervention with a covered stent. After percutaneous biopsy, vascular perforation must always be considered. Computed tomography provides a reliable and quick diagnosis. Minimally invasive percutaneous insertion of a covered stent is the therapy of choice in the case of a renal artery accessible to stents.

Mechanism of kink band formation in zinc single crystals

Abstract This paper is focused on the mechanism of kink band formation. In the general case, lattice rotation in a kink band may be realized by two sequentially activated simple elastic shears in nearly perpendicular planes. In the case of zinc crystals, compressed along (0001) plane at the temperature 523 K, the first shear may result from stress-induced temporary lattice instability (movement of atoms towards metastable positions in tetrahedric holes), while the second shear occurring along a temporary ‘new-positioned’ basal plane immediately ‘rebuilds’ the stable lattice.

Курганцева миша (Mus spicilegus) на Західному Поділлі: експансія на лівобережжі Дністра

New findings of the mound-building mouse on the left bank of the Dniester in the interfluve of its tributaries—the Dzhuryn and the Nichlava (Chortkiv Raion, Ternopil Oblast)—are described. The presence of Mus spicilegus was established based on findings of food stocks common for this species in the form of mounds, which are easy to detect in the field and which can be clearly diagnosed. Both single mounds and their clusters were taken into account. The specifics of biotopic distribution, formation of food reserves, and the role in trophic chains of this species under conditions of the studied region are indicated. The mound-building mouse is one of the few rodent species that maintain a high abundance under conditions of intensive agriculture, which involves mechanical tillage several times a year and a significant level of chemical use. The distribution of the studied species is influenced primarily by two factors: the level of agricultural techniques in agricultural production (arable farming and crop care, quality of harvesting) and the distance from uncultivated areas. The mound-building mouse usually inhabits agricultural lands with a low level of agriculture (minimal chemicalization and mechanical tillage). These are lands allocated for private gardening or farming. Such lands have increased weeds and crop losses during harvesting, which creates a rich food base. After harvesting, such lands usually do not undergo long-term tillage. Results show that the settlement of arable lands comes from natural or other uncultivated areas, where the nuclei of populations are concentrated. In autumn, under the above favourable conditions, population growth is observed in adjacent cultivated lands, where winter food reserves are formed in the form of characteristic mounds. On large-area crops of monocultures cultivated by large agricultural firms, mounds are usually absent. The level of agro-technical pressure on the same area varies from year to year. This causes temporary instability in the appearance of mounds. They disappear where anthropogenic impact has re-emerged significantly and re-appear where there has been a weakening. The role of the mound-building mouse in trophic chains and in maintaining regional biodiversity is shown.

Dynamics of the bacterial gut microbiota during controlled human infection with Necator americanus larvae

ABSTRACT Hookworms are soil-transmitted helminths that use immune-evasive strategies to persist in the human duodenum where they are responsible for anemia and protein loss. Given their location and immune regulatory effects, hookworms likely impact the bacterial microbiota. However, microbiota studies struggle to deconvolute the effect of hookworms from confounders such as coinfections and malnutrition. We thus used an experimental human hookworm infection model to explore temporal changes in the gut microbiota before and during hookworm infection. Volunteers were dermally exposed to cumulative dosages of 50, 100 or 150 L3 Necator americanus larvae. Fecal samples were collected for microbiota profiling through 16S rRNA gene amplicon sequencing at weeks zero, four, eight, fourteen and twenty. During the acute infection phase (trial week zero to eight) no changes in bacterial diversity were detected. During the established infection phase (trial week eight to twenty), bacterial richness (Chao1, p = .0174) increased significantly over all volunteers. No relation was found between larval dosage and diversity, stability or relative abundance of individual bacterial taxa. GI symptoms were associated with an unstable microbiota during the first eight weeks and rapid recovery at week twenty. Barnesiella, amongst other taxa, was more abundant in volunteers with more GI symptoms throughout the study. In conclusion, this study showed that clinical GI symptoms following N. americanus infection are associated with temporary microbiota instability and relative abundance of specific bacterial taxa. These results suggest a possible role of hookworm-induced enteritis on microbiota stability.

Generating PBHs and small-scale GWs in two-field models of inflation

Primordial black holes (PBHs) generated by gravitational collapse of large primordial overdensities can be a fraction of the observed dark matter. In this paper, we introduce a mechanism to produce a large peak in the primordial power spectrum (PPS) in two-field inflationary models characterized by two stages of inflation based on a large non-canonical kinetic coupling. This mechanism is generic to several two-field inflationary models, due to a temporary tachyonic instability of the isocurvature perturbations at the transition between the two stages of inflation. We numerically compute the primordial perturbations from largest scales to the small scales corresponding to that of PBHs using an extension of BINGO (BI-spectra and Non-Gaussianity Operator). Moreover we numerically compute the stochastic background of gravitational waves (SBGW) produced by second order scalar perturbations within frequencies ranging from nano-Hz to KHz that covers the observational scales corresponding to Pulsar Timing Arrays, Square Kilometer Array to that of Einstein telescope. We discuss the prospect of its detection by these proposed and upcoming gravitational waves experiments.

Combined Noise and Clock CRLB Error Model for the Optimization of Node Location in Time Positioning Systems

The emergence of autonomous vehicles with high needs for accuracy in location has hardened the requirements of the positioning systems used for navigation. Local Positioning Systems (LPS) have shown an excellent adaptation to these conditions, thanks to stability and reduction in the levels of positioning uncertainty. The accuracy achieved by methodologies based on temporal measurements depends mainly on the uncertainties in the measurements of these systems. In this aspect, the presence of noise and the existence of temporary instabilities in measurement clocks, depending on the distribution of sensors in the environment, acquire great relevance. In this article, we introduce for the first time in the authors' best knowledge a Cramér-Rao Lower Bound (CRLB) model for the quantification of the global uncertainty in positioning systems caused by both noise and temporary instabilities in the measurement devices. Additionally, this technique is applied to the optimization of sensor distributions for Time of Arrival (TOA), Time Difference of Arrival (TDOA) and Asynchronous TDOA (A-TDOA) architectures using a Genetic Algorithm in a non-uniform 3D environment. Results show that A-TDOA methodology significantly overcomes synchronous architectures in terms of global accuracy and stability when noise and clock errors are considered in time measurements of LPS applications.

Drooping of Gerbera flower heads: mechanical and structural studies of a well-known phenomenon.

Gerbera, one of the most loved cut flowers, is (in)famous for the drooping of its flower heads under dehydration. This effect has been quantified by analysing both fully turgescent and wilting peduncles of Gerbera jamesonii 'Nuance'. Wilting peduncles display pronounced bending in the region directly below the inflorescence after 24 h of dehydration, while the rest of the peduncle remains upright. Using anatomical measurements and three-point bending tests, we have analysed whether this phenomenon is caused by mechanical and/or geometrical alterations. We have found that both the flexural rigidity and the axial second moment of area are significantly decreased in the apical part of wilting peduncles, whereas the bending elastic modulus shows no significant change. Moreover, cross-sections of wilting peduncles ovalize significantly more than those of turgescent peduncles and exhibit considerable shrinkage of the parenchyma, taking up the majority of the cross-sectional area. Generally, the drooping of wilting Gerbera flowers can be regarded as a temporary instability of a rod-shaped cellular solid caused by anatomical differences (tissue arrangement, existence or the absence of a pith cavity) and geometrical changes (the decrease of axial second moment of area, cross-sectional ovalization, shrinkage of tissues) between the apical and basal regions of their peduncles.