175 research outputs found
On a Statistical Mechanics Approach to Some Problems of the Social Sciences
This work is a survey of some results on a statistical mechanics approach to the social sciences emerged in the last two decades. The pioneering work of Daniel McFadden, known as discrete choice theory, is interpreted in terms of a non-interacting model and extended along the lines of the Brock and Durlauf interacting systems. The generalization to the multi-populated model is presented and two specific case studies are reviewed with their phenomenological and theoretical analysis
Optimization Strategies in Complex Systems
We consider a class of combinatorial optimization problems that emerge in a
variety of domains among which: condensed matter physics, theory of financial
risks, error correcting codes in information transmissions, molecular and
protein conformation, image restoration. We show the performances of two
algorithms, the``greedy'' (quick decrease along the gradient) and
the``reluctant'' (slow decrease close to the level curves) as well as those of
a``stochastic convex interpolation''of the two. Concepts like the average
relaxation time and the wideness of the attraction basin are analyzed and their
system size dependence illustrated.Comment: 8 pages, 3 figure
Low Vitamin K and Vitamin D Dietary Intake in Patients with Inflammatory Bowel Diseases
The inadequate dietary intake of Vitamin D and Vitamin K is an easily reversible factor
favoring IBD-associated bone loss, but data on Vitamin K are lacking. A 28-item quantitative food
frequency questionnaire was administered to 193 IBD patients (89 Crohnâs disease and 104 ulcerative
colitis), and 199 controls. Patientsâ demographics, clinical and laboratory findings were analyzed in
relation to recommended daily allowances. VitD intake was inadequate both in the IBD and control
patients (8.3 ± 4.5 ”g/day in IBD, 53.1% RDA, and 9.7 ± 5.9 ”g/day, 63.2% RDA, respectively).
Conversely, the mean ViK intake was less than adequate in IBD, at 116.7 ± 116.3 ”g/day (78.7% RDA),
and high in controls, at 203.1 ± 166.9 ”g/day (138.8% RDA). Nonetheless, due to marked interindividual differences, diets were severely lacking VitK in 40% of UC and 49% of CD patients,
more so in females and those with active disease. The intake of Vit D was non-significantly lower
in colitis than that in Crohnâs disease (7.9 vs. 8.7 ”g/day). The opposite was observed for VitK
(123.5 vs. 107.0 ”g/day). Thus, the diet lacks the micronutrients involved in bone wellbeing in a large
proportion of IBD patients. While VitD supplementation is the rule, VitK shortages need proactive
nutritional intervention.
Keywords: IBD; vitamin K; vitamin D; diet in IB
Ultrametricity in the Edwards-Anderson Model
We test the property of ultrametricity for the spin glass three-dimensional
Edwards-Anderson model in zero magnetic field with numerical simulations up to
spins. We find an excellent agreement with the prediction of the mean
field theory. Since ultrametricity is not compatible with a trivial structure
of the overlap distribution our result contradicts the droplet theory.Comment: typos correcte
Combined Effects of Age and Comorbidities on Electrocardiographic Parameters in a Large Non-Selected Population
Background: Previous studies have evaluated average electrocardiographic (ECG) values in healthy subjects or specific subpopulations. However, none have evaluated ECG average values in not selected populations, so we examined ECG changes with respect to age and sex in a large primary population. Methods: From digitized ECG stored from 2008 to 2021 in the Modena province, 130,471 patients were enrolled. Heart rate, P, QRS and T wave axis, P, QRS and T wave duration, PR interval, QTc, and frontal QRS-T angle were evaluated. Results: All ECG parameters showed a dependence on age, but only some of them with a straight-line correlation: QRS axis (p < 0.001, R2 = 0.991, r = 0.996), PR interval (p < 0.001, R2 = 0.978, r = 0.989), QTc (p < 0.001, R2 = 0.935, r = 0.967), and, in over 51.5 years old, QRS-T angle (p < 0.001, R2 = 0.979, r = 0.956). Differences between females and males and in different clinical settings were observed. Conclusions: ECG changes with ageing are explainable by intrinsic modifications of the heart and thorax and with the appearance of cardiovascular diseases and comorbidities. Age-related reference values were computed and applicable in clinical practice. Significant deviations from mean values and from Z-scores should be investigated
Long-term outcomes of acute severe ulcerative colitis in the rescue therapy era: A multicentre cohort study
BACKGROUND: The longâterm course of ulcerative colitis after a severe attack is poorly understood. Secondâline rescue therapy with cyclosporine or infliximab is effective for reducing shortâterm colectomy but the impact in the longâterm is controversial. OBJECTIVE: The purpose of this study was to evaluate the longâterm 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 followâup visit or death. The primary endâpoint was longâterm 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 followâup was 44 months (interquartile range, 21â85). Colectomyâfree 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 steroidâresponders (logârank test, p = 0.02). At multivariate analysis response to steroids was independently associated with a lower risk of longâterm colectomy (adjusted odds ratio = 0.5; 95% confidence interval, 0.2â0.8), while previous exposure to antitumour necrosis factorâα agents was associated with an increased risk (adjusted odds ratio = 3.0; 95% confidence interval, 1.5â5.7). 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 longâterm colectomy, especially if previously exposed to antitumour necrosis factorâα agents or if rescue therapy during the acute attack was required because of steroid refractoriness
A comparison of diagnostic tests for lactose malabsorption - which one is the best?
<p>Abstract</p> <p>Background</p> <p>Perceived milk intolerance is a common complaint, and tests for lactose malabsorption (LM) are unreliable. This study assesses the agreement between diagnostic tests for LM and describes the diagnostic properties of the tests.</p> <p>Methods</p> <p>Patients above 18 years of age with suspected LM were included. After oral intake of 25 g lactose, a combined test with measurement of serum glucose (s-glucose) and hydrogen (H2) and methane (CH4) in expired air was performed and symptoms were recorded. In patients with discrepancies between the results, the combined test was repeated and a gene test for lactose non-persistence was added. The diagnosis of LM was based on an evaluation of all tests. The following tests were compared: Increase in H2, CH4, H2+CH4 and H2+CH4x2 in expired air, increase in s-glucose, and symptoms. The agreement was calculated and the diagnostic properties described.</p> <p>Results</p> <p>Sixty patients were included, seven (12%) had LM. The agreement (kappa-values) between the methods varied from 0.25 to 0.91. The best test was the lactose breath test with measurement of the increase in H2 + CH4x2 in expired air. With a cut-off level < 18 ppm, the area under the ROC-curve was 0.967 and sensitivity was 100%. This shows that measurement of CH4 in addition to H2 improves the diagnostic properties of the breath test.</p> <p>Conclusion</p> <p>The agreement between commonly used methods for the diagnosis of LM was unsatisfactory. A lactose breath test with measurement of H2 + CH4x2 in expired air had the best diagnostic properties.</p
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