26 research outputs found
Multiplicative versus additive noise in multi-state neural networks
The effects of a variable amount of random dilution of the synaptic couplings
in Q-Ising multi-state neural networks with Hebbian learning are examined. A
fraction of the couplings is explicitly allowed to be anti-Hebbian. Random
dilution represents the dying or pruning of synapses and, hence, a static
disruption of the learning process which can be considered as a form of
multiplicative noise in the learning rule. Both parallel and sequential
updating of the neurons can be treated. Symmetric dilution in the statics of
the network is studied using the mean-field theory approach of statistical
mechanics. General dilution, including asymmetric pruning of the couplings, is
examined using the generating functional (path integral) approach of disordered
systems. It is shown that random dilution acts as additive gaussian noise in
the Hebbian learning rule with a mean zero and a variance depending on the
connectivity of the network and on the symmetry. Furthermore, a scaling factor
appears that essentially measures the average amount of anti-Hebbian couplings.Comment: 15 pages, 5 figures, to appear in the proceedings of the Conference
on Noise in Complex Systems and Stochastic Dynamics II (SPIE International
On metastable configurations of small-world networks
We calculate the number of metastable configurations of Ising small-world
networks which are constructed upon superimposing sparse Poisson random graphs
onto a one-dimensional chain. Our solution is based on replicated
transfer-matrix techniques. We examine the denegeracy of the ground state and
we find a jump in the entropy of metastable configurations exactly at the
crossover between the small-world and the Poisson random graph structures. We
also examine the difference in entropy between metastable and all possible
configurations, for both ferromagnetic and bond-disordered long-range
couplings.Comment: 9 pages, 4 eps figure
Atopic dermatitis and indoor use of energy sources in cooking and heating appliances
Background: Atopic dermatitis (AD) prevalence has considerably increased worldwide in recent years. Studying indoor environments is particularly relevant, especially in industrialised countries where many people spend 80% of their time at home, particularly children. This study is aimed to identify the potential association between AD and the energy source (biomass, gas and electricity) used for cooking and domestic heating in a Spanish schoolchildren population.
Methods: As part of the ISAAC (International Study of Asthma and Allergies in Childhood) phase III study, a cross-sectional population-based survey was conducted with 21,355 6-to-7-year-old children from 8 Spanish ISAAC centres. AD prevalence, environmental risk factors and the use of domestic heating/cooking devices were assessed using the validated ISAAC questionnaire. Crude and adjusted odds ratios (cOR, aOR) and 95% confidence intervals (CIs) were obtained. A logistic regression analysis was performed (Chi-square test, p-value < 0.05).
Results: It was found that the use of biomass systems gave the highest cORs, but only electric cookers showed a significant cOR of 1.14 (95% CI: 1.01-1.27). When the geographical area and the mother’s educational level were included in the logistic model, the obtained aOR values differed moderately from the initial cORs. Electric heating was the only type which obtained a significant aOR (1.13; 95% CI: 1.00-1.27). Finally, the model with all selected confounding variables (sex, BMI, number of siblings, mother’s educational level, smoking habits of parents, truck traffic and geographical area), showed aOR values which were very similar to those obtained in the previous adjusted logistic analysis. None of the results was statistically significant, but the use of electric heating showed an aOR close to significance (1.14; 95% CI: 0.99-1.31).
Conclusion: In our study population, no statistically significant associations were found between the type of indoor energy sources used and the presence of AD
Elective Cancer Surgery in COVID-19-Free Surgical Pathways During the SARS-CoV-2 Pandemic: An International, Multicenter, Comparative Cohort Study.
PURPOSE: As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19-free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS: This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19-free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS: Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19-free surgical pathways. Patients who underwent surgery within COVID-19-free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19-free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score-matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19-free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION: Within available resources, dedicated COVID-19-free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks
Elective cancer surgery in COVID-19-free surgical pathways during the SARS-CoV-2 pandemic: An international, multicenter, comparative cohort study
PURPOSE As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19–free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19–free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19–free surgical pathways. Patients who underwent surgery within COVID-19–free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19–free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score–matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19–free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION Within available resources, dedicated COVID-19–free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks
Two-cycles in spin-systems: sequential versus synchronous updating in multi-state Ising-type ferromagnets
Hamiltonians for general multi-state spin-glass systems with Ising symmetry are derived for both sequential and synchronous updating of the spins. The possibly different behaviour caused by the way of updating is studied in detail for the (anti)-ferromagnetic version of the models, which can be solved analytically without any approximation, both thermodynamically via a free-energy calculation and dynamically using the generating functional approach. Phase diagrams are discussed and the appearance of two-cycles in the case of synchronous updating is examined. A comparative study is made for the Q-Ising and the Blume-Emery-Griffiths ferromagnets and some interesting physical differences are found. Numerical simulations confirm the results obtained. Copyright Springer-Verlag Berlin/Heidelberg 2004
Effectiveness of biologic therapy on disease activity in ankylosing spondylitis: a BIOBADASER III observational study
Background The advent of biologic therapy (BT) in ankylosing spondylitis (AS) has substantially benefited patients with inadequate response to conventional therapy. However, it is known patients with inadequeate response to a 1st BT have worse response to 2nd and further lines.
Objectives To analyze the effectiveness of BT in biologic-naïve and biologic-experienced real-world AS patients, measuring response through change in activity indexes (ASDAS-CRP and BASDAI) and percentage of low activity and inactive disease at 12 months.
Methods Data were obtained from BIOBADASER III, an ongoing observational longitudinal multicenter cohort of patients with rheumatic diseases treated with BT or targeted synthetic DMARDs. Patients were divided into 2 groups, according to their state before entering the study: BT-naïve (BTn) receiving their 1st BT, and BT-experienced (BTe) receiving their 2nd or further BT; regardless of the specific drug they received. Disease activity indexes (DAI) were collected at baseline and after 12 months of BT; mean and SD was calculated for each group and interpreted according to ASDAS disease activity states and, since not established, analogous categories previously used for BASDAI (<2 inactive, ≥2 <4 low, ≥4 <6 high, ≥6 very high)1. Clinical response was assessed by ASDAS improvement cut-offs (≥1.1 clinically important improvement (CII), ≥2 major improvement (MI)) and BASDAI CII (≥1.1)2, BASDAI change (Δ) ≥2 or BASDAI50.
Results 846 patients, (29.3% women, mean age 47.6 years) were included, 422 BTn and 424 BTe. Mean DAI results (table 1): at baseline, AS had high disease activity by BASDAI (>4) and ASDAS (>2.1 to 1.3 to <2.1), reaching BASDAI CII; ΔBASDAI≥2 was only achieved in BTn. No group reached BASDAI50. ASDAS CII was reached in all groups, but MI was not seen. Percentage of patients achieving low disease activity and inactive disease are summarized at table 2, being overall higher for the BTn compared to the BTe group.
Conclusion The mean disease activity on patients starting biologic therapy is high. A clinically important improvement is met after 12 months of therapy, irrespectively of the index used or the prior use of biologics. The delta in DAI is bigger in the biologic-naïve group who receive the 1st BT. The biologic-naïve group also reaches a higher percentage of low disease activity and inactive disease. Further analysis is needed to see if these tendencies remain after separating the groups per type of biologic drug