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Covariance structure analysis methods for testing invariance in reliability and stability coefficients in multi-wave, multi-indicator models are discussed. Alternative approaches are outlined, which are straightforward and simpler than the reparameterization recently proposed by Alanen, Leskinen and Kuusinen.
Comparative analysis of conformational stabilities was performed for two widely used genetic reporters, EGFP and DsRed, proteins exhibiting similar beta-can folds, but possessing different oligomeric organization and chromophore structures. Two factors affecting protein stability in vitro, such as elevated temperatures and a chaotropic agent guanidine hydrochloride, were studied. In vivo tolerance of the fluorescence proteins to proteasomal-based degradation was studied in insect and mammalian cells, and in Xenopus embryos. The apparent rate constants of thermal and GdmCl-induced denaturation were several orders of magnitude lower for DsRed than for EGFP. DsRed lifetimes severalfold longer than those of EGFP were observed in cultured cells and in embryos. The remarkable fluorescence stability of DsRed under the all conditions that have been studied is attributed to a significant extent to its tetrameric organization. Therefore, DsRed can be used as a genetic reporter and advanced population marker with a significantly extended intracellular lifespan.
Electron paramagnetic resonance spectroscopy was used to determine relative peptide orientation within homodimeric, alpha-helical coiled-coil structures. Introduction of cysteine (Cys) residues into peptides/proteins for spin labeling allows detection of their oligomerization from exchange broadening or dipolar interactions between residues within 25 A of each other. Two synthetic peptides containing Cys substitutions were used: a 35-residue model peptide and the 30-residue ProP peptide. The model peptide is known to form a stable, parallel homodimeric coiled coil, which is partially destabilized by Cys substitutions at heptad a and d positions (peptides C30a and C33d). The ProP peptide, a 30-residue synthetic peptide, corresponds to residues 468-497 of osmoregulatory transporter ProP from Escherichia coli. It forms a relatively unstable, homodimeric coiled coil that is predicted to be antiparallel in orientation. Cys was introduced in heptad g positions of the ProP peptide, near the N-terminus (K473C, creating peptide C473g) or closer to the center of the sequence (E480C, creating peptide C480g). In contrast to the destabilizing effect of Cys substitution at the core heptad a or d positions of model peptides C30a and C33d, circular dichroism spectroscopy showed that Cys substitutions at the heptad g positions of the ProP peptide had little or no effect on coiled-coil stability. Thermal denaturation analysis showed that spin labeling increased the stability of the coiled coil for all peptides. Strong exchange broadening was detected for both C30a and C33d, in agreement with a parallel structure. EPR spectra of C480g had a large hyperfine splitting of about 90 G, indicative of strong dipole-dipole interactions and a distance between spin-labeled residues of less than 9 A. Spin-spin interactions were much weaker for C473g. These results supported the hypothesis that the ProP peptide primarily formed an antiparallel coiled coil, since formation of a parallel dimer should result in similar spin-spin interactions for the spin-labeled Cys at both sites.
Although extensive research has been conducted on psychophysiological reactivity, there is a paucity of data concerning the temporal stability of such procedures. Test-retest reliability of experimental stressors from both mental and physical modalities were assessed using a wide range of psychophysiological measures. Absolute baseline and test values demonstrated adequate test-retest reliability for skin temperature, skin resistance, vasomotor response, heart rate, systolic and diastolic blood pressure, while forearm EMG had low reliability. Difference scores, which represent change from baseline to test conditions, did not have adequate reliability. These data represent a necessary step towards standardization of psychophysiological assessment techniques and thus may guide further use of more reliable methods.
Freeze-drying (lyophilization) of biologically active materials such as human live virus vaccines is an accepted method of preserving potency. Since freeze-drying does not assure total stability, a formal system of monitoring stability, i.e., potency, has been established. Two experimental desings are utilized: (1) Long term studies to duplicate normal use storage at -20 degrees C and 2-8 degrees C and (2) Accelerated studies which predict long term stability through regression analysis using the Arrhenius equation. Data summarizing stability experience over a long period of study will be presented.
Comparative quantitative analysis of physiological asymmetry of the optokinetic nystagmus produced predominantly by central optokinetic stimulation (field of vision = 30 degrees) or peripheral stimulation (field of vision = 110 degrees) reveals an objective correlation between the asymmetry coefficient of the central optokinetic nystagmus with respect to the angular velocity of its slow phase and susceptibility to motion sickness caused by Coriolis and pseudocoriolis acceleration, the nystagmus velocity being up to 45 deg/sec.
Analysis of 57,514 initial complaints for divorce, separate maintenance, and annulment filed in California during the first six months of 1968 reveals that physicians are considerably less prone to marital failure than men of comparable age in the general population. Furthermore, when compared to professionals in general, doctors also appear less prone to marital collapse. For physicians, marriages break down in the greatest numbers and at the greatest rate between the ages of 35 and 44. Women doctors are at least 40% more prone to marital instability than men, and black physicians are nearly 70% more prone to divorce than their white colleagues. Of the individual specialists, orthopedists and psychiatrists possibly have the highest rates of marital demise.
The long-term stability of Class II, Division 1 nonextraction therapy, using cervical face-bows with full fixed orthodontic appliances was evaluated for 42 randomly selected patients. Part 1, a study model analysis, was published in the March 1996 issue of the JOURNAL. Each patient was treated by the same practitioner, with the same techniques, and the treatment goals had been attained for all patients. Pretreatment records were taken at a mean age of 11.5 years; the posttreatment and postretention records were taken 3.0 and 11.6 years later, respectively. The results showed that the ANB angle decreased 2 degrees during treatment, most of which was due to the 1.6 degree decrease of the SNA angle. The mandibular plane angle was not changed significantly during treatment. Although upper incisor inclination was maintained during treatment, the lower incisor was proclined 2.3 degrees and the lower molar was tipped back 4 degrees. Of the 22 cephalometric measures evaluated, only four indicated relapse related with the treatment change. Three of the four measures pertain to lower incisor retroclination subsequent to excessive proclination. The ratio of treatment proclination of incisors to posttreatment retroclination is approximately 5:1. Similarly, for every 3 degrees of molar tip back, there was approximately 1 degree of relapse. It is concluded that nonextraction therapy for Class II malocclusion can be largely stable when the orthodontist ensures proper patient selection and compliance and attains treatment objectives.
The effect of low temperatures on the stability of characteristic signals during electron probe analysis of microdroplets has been investigated. The kinetics of the characteristic Na, K and Cl signals from lyophilized droplets of either KCl or NaCl salts were observed for 1200 s within an electron microprobe whose specimen stage was maintained at -140 degrees C. Samples were irradiated with 15 keV electrons, at beam current densities ranging from 7 x 10(-4) to 7 x 10(-3) A . cm-2. The signals measured increased and then, in some cases, decreased. The duration and amplitude of the increases varied depending on beam current density, mass thickness of the sample and on the element concerned. The increase sometimes reached 6 times the initial value, a level never observed at room temperature. No proportionality was observed between X-ray intensity and concentration for measurements after the first 10 s irradiation. Proportionality was only restored when droplets had been irradiated for some time. In no case did the stability of characteristic signals improve. Analysis of droplets at -140 degrees C suggests that under electron beam irradiation they undergo a change not observable at room temperature.
The paper reviews single-neuron learning rules for minor component analysis and suggests a novel minor component learning rule. In this rule, the weight vector length is self-stabilizing, i.e., moving towards unit length in each learning step. In simulations with low- and medium-dimensional data, the performance of the novel learning rule is compared with previously suggested rules.
STUDY DESIGN: An evaluation of the intervertebral stability of transpedicular instrumentation in posterolateral lumbar fusions by roentgen stereophotogrammetric analysis. OBJECTIVES: To determine the in vivo intervertebral stability of posterolateral lumbar fusions augmented with transpedicular screws and plates. SUMMARY OF BACKGROUND DATA: Transpedicular bone screw systems have been found to be as safe and clinically effective as other types of devices in stabilizing surgery of the spine. Many experimental studies have yielded basic data on the stabilizing implant effect in vitro, but the exact in vivo stabilizing effect on human lumbar vertebrae has not been presented previously. METHODS: In 12 patients, the intervertebral stability of posterolateral fusion in the lower lumbar spine augmented with transpedicular screws and plates was evaluated by serial roentgen stereophotogrammetric analysis with the patients in supine and erect positions 1 year after surgery. RESULTS: Screws in each fused vertebra yielded stable fixation or permitted sagittal intervertebral translations smaller than 1 mm induced by the positional change. A widely decompressed and destabilized vertebra without screw fixation yielded persisting intervertebral translations. CONCLUSIONS: The current study demonstrated the adequacy of in vivo stability of lumbar fusions augmented with transpedicular screws and plates. Sagittal translation seems easier to elicit than movements along the other three-dimensional axes. A widely decompressed and destabilized vertebra without screw fixation increases the risk for persisting intervertebral translations. The roentgen stereophotogrammetric analysis technique described seems to be a good way of comparing the in vivo behavior of different implant systems.
In this paper, we obtain new sufficient conditions ensuring existence, uniqueness, and global asymptotic stability (GAS) of the equilibrium point for a general class of delayed neural networks (DNNs) via nonsmooth analysis, which makes full use of the Lipschitz property of functions defining DNNs. Based on this new tool of nonsmooth analysis, we first obtain a couple of general results concerning the existence and uniqueness of the equilibrium point. Then those results are applied to show that existence assumptions on the equilibrium point in some existing sufficient conditions ensuring GAS are actually unnecessary; and some strong assumptions such as the boundedness of activation functions in some other existing sufficient conditions can be actually dropped. Finally, we derive some new sufficient conditions which are easy to check. Comparison with some related existing results is conducted and advantages are illustrated with examples. Throughout our paper, spectral properties of the matrix (A + Atau) play an important role, which is a distinguished feature from previous studies. Here, A and Atau are, respectively, the feedback and the delayed feedback matrix defining the neural network under consideration.
To elucidate the molecular mechanism of thermal stability, it is essential to determine what are the major free energy components that contribute significantly to the total free energy difference caused by amino acid mutations. In this work, we carried out free energy calculations based on all-atom molecular dynamics simulations to investigate the effect of three hydrophobic mutations at the same position, I56A, I56V and I56F of human lysozyme. The calculated free energy differences are in good agreement with the experimental values in all cases. From free energy component analysis, we found that small changes in stability in the I56A and I56V mutants originate from the short-range Lennard-Jones interactions, whereas the I56F mutant is largely destabilized owing to the changes in the long-range electrostatic interactions. The calculated results are also compared with the free energy components determined by an empirical relationship based on the native-state structure and thermodynamic data. Although this relationship has been shown to be very successful in reproducing the stability changes caused by various amino acid substitutions in several proteins, the changes of stability in I56V and I56F mutants are not reproduced very well. By comparing the free energy components calculated by these two approaches, we showed that the effect of the long-range interaction on the stability changes may be underestimated in the empirical relationships when the structural change caused by mutation is relatively small, as in I56F. It is also suggested that estimation of the change in accessible surface area, deltadeltaASA, may be overestimated if the structure around the mutation site in the denatured state is native-like, which would cause overestimation of the free energy change as in the case of I56V. Our results clearly show that the combined approach of the free energy calculation based on the all-atom molecular dynamics simulation and the empirical relationships is very useful for understanding the detailed mechanism of protein stability.
The long-term stability of Class II, Division 1 nonextraction therapy remains poorly described. This study evaluates the face-bow therapy, in conjunction with full-fixed appliance therapy, of 42 patients (34 females and 8 males) who were treated by the same practitioner. Treatment goals had been attained for all patients. The pretreatment, posttreatment, and postretention records were taken at 11.5, 14.5, and 23.1 years, respectively. The results showed that mandibular and maxillary arch widths were increased significantly during treatment. Mandibular intercanine width decreased 0.3 mm during the postretention period; the remaining width measures increased or remained stable. Arch length, which did not change during treatment, decreased 1.0 mm after treatment. Overjet and overbite decreased 4.4 mm and 2.5 mm, respectively, during treatment. Both overjet (0.5 mm) and overbite (0.4 mm) showed small increases after retention. Mandibular incisor irregularity was decreased 2.7 mm during treatment and increased only 0.4 mm after treatment. Within the limits of this study, it is concluded that, when the described techniques are used, nonextraction therapy for patients with Class II malocclusion is largely stable.
OBJECTIVES: To systematically evaluate the influence of concave versus convex emergence profiles on midfacial mucosal stability in partially edentulous patients restored with implant-supported single restorations. MATERIALS AND METHODS: A systematic review and meta-analysis of randomized controlled trials (RCTs) was conducted and registered in PROSPERO (CRD420251139042). An electronic search in MEDLINE (PubMed) and Embase was performed up to May 7, 2026. Eligible studies included RCTs comparing concave (test group) and convex (control group) transmucosal prosthetic designs and reporting midfacial mucosal level changes (mm). Data extraction and risk of bias assessment (RoB 2) were performed independently. A random-effects meta-analysis was conducted using weighted mean differences (MDs) and 95% confidence intervals (CIs). Heterogeneity was assessed using the I2 statistic and sensitivity analyses were performed to evaluate the robustness of the findings. RESULTS: Four RCTs including 144 implants with a 12-month follow-up were included. Of these, 128 implants contributed to the quantitative synthesis, with 66 implants allocated to the concave/modified emergence profile group and 62 implants allocated to the convex/non-concave emergence profile group. The pooled analysis demonstrated a mean difference of -0.31 mm (95% CI -0.63 to 0.02; p = 0.064), indicating a trend toward greater midfacial mucosal recession with convex emergence profiles compared with concave designs. Between-study heterogeneity was low to moderate (I2 = 28%), suggesting consistent findings across studies. Sensitivity analyses confirmed the direction of the effect, with pooled estimates ranging from -0.12 to -0.43 mm. Exclusion of one study resulted in a statistically significant difference favoring concave emergence profiles (-0.43 mm; 95% CI -0.70 to -0.16; p = 0.002). CONCLUSIONS: Convex emergence profiles are associated with a tendency toward increased midfacial mucosal recession. Concave profiles are preferable to support peri-implant soft-tissue stability. CLINICAL RELEVANCE: Emergence profile design should be considered an integral component of prosthetic and surgical planning. The use of concave transmucosal contours during provisionalization and definitive restoration may contribute to improved peri-implant soft tissue stability and enhanced esthetic outcomes.
Some parameters, such as assimilable organic carbon (AOC), chloramine residual, water temperature, and water residence time, were measured in drinking water from distribution systems in a northern city of China. The measurement results illustrate that when chloramine residual is more than 0.3 mg/L or AOC content is below 50 microg/L, the biological stability of drinking water can be controlled. Both chloramine residual and AOC have a good relationship with Heterotrophic Plate Counts (HPC)(log value), the correlation coefficient was--0.64 and 0.33, respectively. By regression analysis of the survey data, a statistical equation is presented and it is concluded that disinfectant residual exerts the strongest influence on bacterial growth and AOC is a suitable index to assess the biological stability in the drinking water.
The thermolysin-like protease (TLP) produced by Bacillus stearothermophilus CU21 (TLP-ste) differs at 43 positions from the more thermally stable thermolysin (containing 316 residues in total). Of these differences, 26 were analysed by studying the effect of replacing residues in TLP-ste by the corresponding residues in thermolysin. Several stabilizing mutations were identified but, remarkably, considerable destabilizing mutational effects were also found. A Tyr-rich three residue insertion in TLP-ste (the only deletional/insertional difference between the two enzymes) appeared to make an important contribution to the stability of the enzyme. Mutations with large effects on stability were all localized in the beta-pleated N-terminal domain of TLP-ste, confirming observations that this domain has a lower intrinsic stability than the largely alpha-helical C-terminal domain. Rigidifying mutations such as Gly58-->Ala and Ala69-->Pro were among the most stabilizing ones. Apart from this observation, the analyses did not reveal general rules for stabilizing proteins. Instead, the results highlight the importance of context in evaluating the stability effects of mutations.
Over the past fifty years, considerable research in waste stabilization pond operation has led to the development of a number of models used to describe the hydraulic regime and predict treatment efficiency. Models range in complexity from plug or completely mixed simplifications to computational fluid dynamics (CFD) models which are able to predict flow hydraulics at a local level. Information about the exit age of pond effluent can be used to estimate pollutant decay. However, a mechanistic approach to understanding pond operation highlights the importance of knowing both the time and spatial history of pond effluent. A CFD model of a large pond system was constructed to demonstrate various hydraulic scenarios under different boundary conditions. Two scenarios were compared to visually demonstrate the effects of differing hydraulic conditions. Typical mechanistic models were applied to each condition to quantify biological differences. This simple example indicates that integrating biological and localised flow models will lead to a more holistic understanding of pond operation and treatment efficiency.