992 research outputs found
Lorenz-like systems and classical dynamical equations with memory forcing: a new point of view for singling out the origin of chaos
A novel view for the emergence of chaos in Lorenz-like systems is presented.
For such purpose, the Lorenz problem is reformulated in a classical mechanical
form and it turns out to be equivalent to the problem of a damped and forced
one dimensional motion of a particle in a two-well potential, with a forcing
term depending on the ``memory'' of the particle past motion. The dynamics of
the original Lorenz system in the new particle phase space can then be
rewritten in terms of an one-dimensional first-exit-time problem. The emergence
of chaos turns out to be due to the discontinuous solutions of the
transcendental equation ruling the time for the particle to cross the
intermediate potential wall. The whole problem is tackled analytically deriving
a piecewise linearized Lorenz-like system which preserves all the essential
properties of the original model.Comment: 48 pages, 25 figure
Contribution of the massive photon decay channel to neutrino cooling of neutron stars
We consider massive photon decay reactions via intermediate states of
electron-electron-holes and proton-proton-holes into neutrino-antineutrino
pairs in the course of neutron star cooling. These reactions may become
operative in hot neutron stars in the region of proton pairing where the photon
due to the Higgs-Meissner effect acquires an effective mass that
is small compared to the corresponding plasma frequency. The contribution of
these reactions to neutrino emissivity is calculated; it varies with the
temperature and the photon mass as
for . Estimates show that these processes appear as extra
efficient cooling channels of neutron stars at temperatures K.Comment: accepted to publication in Zh. Eksp. Teor. Fiz. (JETP
The Counterpart Principle of Analogical Support by Structural Similarity
We propose and investigate an Analogy Principle in the context of Unary Inductive Logic based on a notion of support by structural similarity which is often employed to motivate scientific conjectures
Which route of antibiotic administration should be used for third molar surgery? A split-mouth study to compare intramuscular and oral intake
Objectives. To compare the effectiveness of two different routes of antibiotic administration in preventing septic complications in patients undergoing third molar extraction.
Materials and Methods. Twenty-four healthy patients requiring bilateral surgical removal of impacted mandibular third molars were successfully enrolled for this study. Depth of impaction, angulation, and relationship of the lower third molars with the mandibular branch had to be overlapping on both sides. A split-mouth design was chosen, so each patient underwent both the first and second surgeries, having for each extraction a different antibiotic route of administration. The second extraction was carried out 1 month later. To compare the effects of the two routes of antibiotic administration, inflammatory parameters, such as edema, trismus, pain, fever, dysphagia and lymphadenopathy were evaluated 2 and 7 days after surgery. Side effects of each therapy were evaluated 48h after surgery.
Results. oral and intramuscular antibiotic therapies overlap in preventing post-operative complications in dental surgery (p>0.05), even if the oral intake, seems to promote the onset of significant gastrointestinal disorders (p=0.003).
Conclusions. This study could help dentists in their ordinary practice to choose the right route of antibiotic administration in the third molar surgery. At the same effectiveness, the higher cost and the minor compliance of the patient seem not to justify a routine antibiotic intramuscular therapy, reserving it for patients with gastrointestinal disorders
Статистический контроль качества испытаний фольги медной электролитической и катанки медной с использованием контрольных карт
Представлен метод статистического контроля правильности и повторяемости процесса проведения испытаний на основе трех фаз: сбора данных, анализа и управления процессом. Показан пример формирования подгрупп для контроля качества испытаний на примере катанки. Представлена причинно-следственная диаграмма Исикава для анализа процесса. Описан метод управления процессом.A method of the statistical surveillance of correctness and repeatability for tests carrying out process on basis of three phases is submitted: data collection, analysis and process control. The example of making up of subgroups for rod tests quality surveillance is shown. Isikava 's cause and effect diagram for process analysis is submitted. Process control method is described
Rosiglitazone Decreases C-Reactive Protein to a Greater Extent Relative to Glyburide and Metformin Over 4 Years Despite Greater Weight Gain: Observations from A Diabetes Outcome Progression Trial (ADOPT)
OBJECTIVE: C-reactive protein (CRP) is closely associated with obesity and cardiovascular disease in both diabetic and nondiabetic populations. In the short term, commonly prescribed antidiabetic agents have different effects on CRP; however, the long-term effects of those agents are unknown. RESEARCH DESIGN AND METHODS: In A Diabetes Outcome Progression Trial (ADOPT), we examined the long-term effects of rosiglitazone, glyburide, and metformin on CRP and the relationship among CRP, weight, and glycemic variables in 904 subjects over 4 years. RESULTS: Baseline CRP was significantly correlated with homeostasis model assessment of insulin resistance (HOMA-IR), A1C, BMI, waist circumference, and waist-to-hip ratio. CRP reduction was greater in the rosiglitazone group by -47.6% relative to glyburide and by -30.5% relative to metformin at 48 months. Mean weight gain from baseline (at 48 months) was 5.6 kg with rosiglitazone, 1.8 kg with glyburide, and -2.8 kg with metformin. The change in CRP from baseline to 12 months was correlated positively with change in BMI in glyburide (r = 0.18) and metformin (r = 0.20) groups but not in the rosiglitazone (r = -0.05, NS) group. However, there was no longer a significant correlation between change in CRP and change in HOMA-IR, A1C, or waist-to-hip ratio in any of the three treatment groups. CONCLUSIONS: Rosiglitazone treatment was associated with durable reductions in CRP independent of changes in insulin sensitivity, A1C, and weight gain. CRP in the glyburide and metformin groups was positively associated with changes in weight, but this was not the case with rosiglitazone
Sample-size dependence of the ground-state energy in a one-dimensional localization problem
We study the sample-size dependence of the ground-state energy in a
one-dimensional localization problem, based on a supersymmetric quantum
mechanical Hamiltonian with random Gaussian potential. We determine, in the
form of bounds, the precise form of this dependence and show that the
disorder-average ground-state energy decreases with an increase of the size
of the sample as a stretched-exponential function, , where the
characteristic exponent depends merely on the nature of correlations in the
random potential. In the particular case where the potential is distributed as
a Gaussian white noise we prove that . We also predict the value of
in the general case of Gaussian random potentials with correlations.Comment: 30 pages and 4 figures (not included). The figures are available upon
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Long-term outcomes of acute severe ulcerative colitis in the rescue therapy era: A multicentre cohort study
BACKGROUND: The long‐term course of ulcerative colitis after a severe attack is poorly understood. Second‐line rescue therapy with cyclosporine or infliximab is effective for reducing short‐term colectomy but the impact in the long‐term is controversial. OBJECTIVE: The purpose of this study was to evaluate the long‐term course of acute severe ulcerative colitis patients who avoid early colectomy either because of response to steroids or rescue therapy. METHODS: This was a multicentre retrospective cohort study of adult patients with acute severe ulcerative colitis admitted to Italian inflammatory bowel disease referral centres from 2005 to 2017. All patients received intravenous steroids, and those who did not respond received either rescue therapy or colectomy. For patients who avoided early colectomy (within 3 months from the index attack), we recorded the date of colectomy, last follow‐up visit or death. The primary end‐point was long‐term colectomy rate in patients avoiding early colectomy. RESULTS: From the included 372 patients with acute severe ulcerative colitis, 337 (90.6%) avoided early colectomy. From those, 60.5% were responsive to steroids and 39.5% to the rescue therapy. Median follow‐up was 44 months (interquartile range, 21–85). Colectomy‐free survival probability was 93.5%, 81.5% and 79.4% at 1, 3 and 5 years, respectively. Colectomy risk was higher among rescue therapy users than in steroid‐responders (log‐rank test, p = 0.02). At multivariate analysis response to steroids was independently associated with a lower risk of long‐term colectomy (adjusted odds ratio = 0.5; 95% confidence interval, 0.2–0.8), while previous exposure to antitumour necrosis factor‐α agents was associated with an increased risk (adjusted odds ratio = 3.0; 95% confidence interval, 1.5–5.7). Approximately 50% of patients required additional therapy or new hospitalisation within 5 years due to a recurrent flare. Death occurred in three patients (0.9%). CONCLUSIONS: Patients with acute severe ulcerative colitis avoiding early colectomy are at risk of long‐term colectomy, especially if previously exposed to antitumour necrosis factor‐α agents or if rescue therapy during the acute attack was required because of steroid refractoriness
c-Jun NH2-Terminal Kinase Activity in Subcutaneous Adipose Tissue but Not Nuclear Factor-κB Activity in Peripheral Blood Mononuclear Cells Is an Independent Determinant of Insulin Resistance in Healthy Individuals
OBJECTIVE Chronic low-grade activation of the immune system (CLAIS) predicts type 2 diabetes via a decrease in insulin sensitivity. Our study investigated potential relationships between nuclear factor-κB (NF-κB) and c-Jun NH2-terminal kinase (JNK) pathways—two pathways proposed as the link between CLAIS and insulin resistance.
RESEARCH DESIGN AND METHODS Adiposity (dual-energy X-ray absorptiometry), waist-to-hip ratio (WHR), and insulin sensitivity (M, hyperinsulinemic-euglycemic clamp) were measured in 22 healthy nondiabetic volunteers (aged 29 ± 11 years, body fat 28 ± 11%). NF-κB activity (DNA-binding assay) and JNK1/2 activity (phosphorylated JNK) were assessed in biopsies of the vastus lateralis muscle and subcutaneous adipose tissue and in peripheral blood mononuclear cell (PBMC) lysates.
RESULTS NF-κB activities in PBMCs and muscle were positively associated with WHR after adjustment for age, sex, and percent body fat (both P 0.1), although it was inversely related to M (r = −0.54, P < 0.05) and explained 29% of its variance. When both NF-κB and JNK1/2 were examined statistically, only JNK1/2 activity in adipose tissue was a significant determinant of insulin resistance (P = 0.02).
CONCLUSIONS JNK1/2 activity in adipose tissue but not NF-κB activity in PBMCs is an independent determinant of insulin resistance in healthy individual
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