Improved Diagonal Hessian Approximations for Large-Scale Unconstrained Optimization

We consider some diagonal quasi-Newton methods for solving large-scale unconstrained optimization problems. A simple and effective approach for diagonal quasi-Newton algorithms is presented by proposing new updates of diagonal entries of the Hessian. Moreover, we suggest employing an extra BFGS update of the diagonal updating matrix and use its diagonal again. Numerical experiments on a collection of standard test problems show, in particular, that the proposed diagonal quasi-Newton methods perform substantially better than certain available diagonal methods

Can the irrigation of soils with Amoxicillin-enriched water cause the proliferation of Bacteria resistant to antibiotics among culturable heterotrophic aerobic soil bacteria?

This study investigated the short-term impact of irrigation with Amoxicillin solutions on the presence of the amoxicillin-resistance trait among culturable soil heterotrophic aerobic bacteria. The microcosm experimental design consisted of 15 days of incubation of 10 g soil samples irrigated daily with distilled water containing increasing doses of amoxicillin (0, 0.1, 1, 10, 100, 1000 µg g-1 of soil day-1). The hypothesis was that continuous daily addition of antibiotics would increase the proportion of antibiotic-resistant bacteria in soils. After the incubation period, the total and antibiotic resistance heterotrophic aerobic bacteria communities were assessed through serial dilution of soil suspensions, followed by agar plate culture enumeration, isolation, identification and microscopy observation. The presence of antibiotic-resistant bacteria was also evaluated directly on treated wastewater used for field irrigation before this microcosm study to assess the amoxicillin-resistant bacteria bioaugmentation hypothesis. Results indicated that the Amoxicillin resistance was widespread among bacteria present in both treated wastewater used for irrigation and in the receiving soil. A microcosm experiment was attempted as a ‘proof of concept’ to demonstrate that irrigation with treated wastewater containing antibiotics would exert selective pressure and promote the proliferation of antibiotic resistance bacteria. Unexpectedly, the results from the microcosm incubations indicated the daily addition of amoxicillin did not increase bacterial antibiotic resistance trait abundance in soils, which even significantly decreased for all tested doses. The antibiotic-resistant species identified among the isolates were Pseudomonas mosselii, P. otitidis, P. mendocina, P. flavescens, Stenotrophomnas maltophilia, Bacillus thuringiensis, Aeromonas veronii, Candida parapsilosis, Streptomyces violaceoruber and Microbacterium barkeri

Transmission dynamics, responses, and clinical features for the first 1100 COVID-19 cases in South Batinah, Oman: Major lessons from a provincial perspective

الملخص: أهداف البحث: هدفت هذه الدراسة إلى استكشاف وتحليل الملامح الوبائية ورصد واستجابة كوفيد-19، وديناميكيات انتقالها وتشكل المجموعات. طرق البحث: تحليل استرجاعي لبيانات الرصد، بما في ذلك تتبع الاتصال، وعوامل الخطر، والمعلومات السريرية. أجريت تحليلات الانحدار اللوجستية الثنائية لتقييم احتمالات القبول، وتشكل المجموعات، وكونه حالة رئيسية. تم توضيح المجموعات باستخدام أنظمة البيانات الجغرافية وتحليل الشبكات وبرامج التصور. النتائج: تم تشخيص ١١٠٠ حالة إصابة بفيروس كوفيد-١٩ في الفترة من ٢٠ مارس إلى ٧ يونيو ٢٠٢٠، وكانت ١٤٤ حالة منها (١٣,١٪) بدون أعراض. كانت المدة المتوسطة من بدء الأعراض حتى القبول في المستشفى ٧ أيام (٤,٥ - ١٠)، ومدة الأعراض نفسها كانت ٥ أيام (٣ - ٩). تم تحديد 89 مجموعة تحتوي على ٧٣٦ مريضا. وتم تمييز ثلاث مراحل توضح إجراءات الرصد والسيطرة. بدأت المجموعات في المرحلة الثانية وزادت وضوحا في المرحلة الثالثة. المرضى الذين تجاوزوا سن ٥٠ عاما وأولئك الذين يعانون من الحمى لديهم فرصة أكبر للقبول في المستشفى، بنسبة ١٢,٨٥ (٩٥٪ م.م. ٥,١٣ – ٣٢,١٩) و ٢,٥٣ (٩٥٪ م.م. ١,٢٤ – ٥,١٧) على التوالي. وقد لوحظ تشكل المجموعات بين الإناث والمرضى الذين لم يظهروا أعراضا وبين سكان ولاية عوابي، بنسب ٢,٣ (٩٥٪ م.م. ١,٧ – ٣,١) و ٦,٣٩ (٩٥٪ م.م. ٢,٣٣ – ١٧,٢) و ٣,٥٤ (٩٥٪ م.م. ٢,٠٦ – ٦,٠٧) على التوالي. وكان لدى المرضى العاملين في قطاعات الشرطة والدفاع فرصة أعلى لكونهم حالة رئيسية، بنسبة ٧,٨٨ (٩٥٪ م.م. ٣,٣٥ – ١٨,٥٢). الاستنتاجات: يجب دعم التدخلات القائمة على الحالات من خلال التدابير الموسعة على مستوى السكان - خاصة قيود الحركة. يعد إنشاء فرق الوقاية أو وحدات المنطقة، أو من خلال الرعاية الأولية أمرا حاسما للسيطرة على الأوبئة المستقبلية. يجب أن تكون الوقاية دائما أولوية للفئات السكانية الضعيفة. Abstract: Objectives: This study was aimed at exploring and analyzing the epidemiological profile, surveillance, and response to COVID-19, including transmission dynamics and cluster formation. Methodology: This was a retrospective analysis of surveillance data, including contact tracing, risk factors, and clinical information. Binary logistic regressions were used to assess the likelihood of admission, cluster formation, and of each individual being an index patient. Clusters were demonstrated through geographic data systems, network analysis, and visualization software. Results: A total of 1100 COVID-19 cases were diagnosed from 20 March to 7 June 2020, of which 144 (13.1%) were asymptomatic. The median time from symptom onset to admission was 7 days (IQR, 4.5–10), and the median symptom duration was 5 days (IQR, 3–9). Eighty-nine clusters containing 736 patients were identified. The surveillance and control actions were divided into three phases. Clusters began to form in phase 2 and became more pronounced in phase 3. Patients ≥50 years of age and patients presenting with fever had relatively higher odds of admission: OR = 12.85 (95% CI 5.13–32.19) and 2.53 (95% CI 1.24–5.17), respectively. Cluster formation was observed among females, asymptomatic patients, and people living in Awabi: OR = 2.3 (95% CI 1.7–3.1), 6.39 (95% CI 2.33–17.2), and 3.54 (95% CI 2.06–6.07), respectively. Patients working in the police and defense sectors had higher odds of being an index patient: OR = 7.88 (95% CI 3.35–18.52). Conclusion: Case-based interventions should be supported by population-wide measures, particularly movement restrictions. Establishing prevention teams or district units, or primary care will be crucial for the control of future pandemics. Prevention should always be prioritized for vulnerable populations