Learning Rays via Deep Neural Network in a Ray-based IPDG Method for High-Frequency Helmholtz Equations in Inhomogeneous Media

We develop a deep learning approach to extract ray directions at discrete locations by analyzing highly oscillatory wave fields. A deep neural network is trained on a set of local plane-wave fields to predict ray directions at discrete locations. The resulting deep neural network is then applied to a reduced-frequency Helmholtz solution to extract the directions, which are further incorporated into a ray-based interior-penalty discontinuous Galerkin (IPDG) method to solve the Helmholtz equations at higher frequencies. In this way, we observe no apparent pollution effects in the resulting Helmholtz solutions in inhomogeneous media. Our 2D and 3D numerical results show that the proposed scheme is very efficient and yields highly accurate solutions.Comment: 30 page

Return migration and re-migration of Brazilian-Japanese and the role of identity in their migration

published_or_final_versionInternational and Public AffairsMasterMaster of International and Public Affair

Probing the Reactivity of the Ce=O Multiple Bond in a Cerium(IV) Oxo Complex

The reactivity of the cerium­(IV) oxo complex [(L_OEt)₂Ce^IV(O)­(H₂O)]·MeC­(O)­NH₂ (<b>1</b>; L_OEt^– = [CoCp­{P­(O)­(OEt)₂}₃]⁻, where Cp = η⁵-C₅H₅) toward electrophiles and Brønsted acids has been investigated. The treatment of <b>1</b> with acetic anhydride afforded the diacetate complex [Ce^IV(L_OEt)₂(O₂CMe)₂] (<b>2</b>). The reaction of <b>1</b> with B­(C₆F₅)₃ yielded [Ce^IV(L_OEt)₂(Me₂CONH₂)₂]­[B­(C₆F₅)₃(OH)]₂ (<b>3</b>), in which the [B­(C₆F₅)₃(OH)]⁻ anions are H-bonded to the O-bound acetamide ligands. The treatment of <b>1</b> with HCl and HNO₃ afforded [Ce^IV(L_OEt)₂Cl₂] and [Ce^IV(L_OEt)₂(NO₃)₂], respectively. Protonation of <b>1</b> with triflic acid (HOTf) gave the diaqua complex [Ce^IV(L_OEt)₂(H₂O)₂]­(OTf)₂ (<b>4</b>), in which the triflate anions are H-bonded to the two aqua ligands. The treatment of <b>1</b> with phenol afforded the phenoxide complex [Ce^IV(L_OEt)₂(OPh)₂] (<b>5</b>). The oxo-bridged bimetallic complex [(L_OEt)₂(Me₂CONH₂)­Ce^IV(O)­NaL_OEt] (<b>6</b>) with the Ce–O_oxo and Na–O_oxo distances of 1.953(4) and 2.341(4) Å, respectively, was obtained from the reaction of <b>1</b> with [NaL_OEt]. Density functional theory calculations showed that the model complex [(L_OMe)₂Ce^IV(Me₂CONH₂)­(O)­NaL_OMe] (<b>6A</b>; L_OMe^– = [CoCp­{P­(O)­(OMe)₂}₃]⁻) contains a polarized CeO multiple bond. The energy for dissociation of the {NaL_OMe} fragment from <b>6A</b> in acetonitrile was calculated to be +33.7 kcal/mol, which is higher than that for dissociation of the H-bonded acetamide from [(L_OMe)₂Ce^IV(O)­(H₂O)]·MeC­(O)­NH₂ (<b>1A</b>) (calculated to be +17.4 kcal/mol). In hexanes containing trace water, complex <b>1</b> decomposed readily to a mixture of a tetranuclear cerium­(IV) oxo cluster, [Ce^IV₄(L_OEt)₄(μ₄-O)­(μ₂-O)₄(μ₂-OH)₂] (<b>7</b>), and a cerium­(III) complex, [Ce^III(L_OEt)₂(H₂O)₂]­[L_OEt] [<b>8</b>(L_OEt)], whereas the cerium/sodium oxo complex <b>6</b> is stable under the same conditions. The crystal structures of <b>3</b>, <b>4</b>·H₂O, <b>6</b>, and <b>8</b>(L_OEt) have been determined

Pooled analysis of WHO Surgical Safety Checklist use and mortality after emergency laparotomy

Background The World Health Organization (WHO) Surgical Safety Checklist has fostered safe practice for 10 years, yet its place in emergency surgery has not been assessed on a global scale. The aim of this study was to evaluate reported checklist use in emergency settings and examine the relationship with perioperative mortality in patients who had emergency laparotomy. Methods In two multinational cohort studies, adults undergoing emergency laparotomy were compared with those having elective gastrointestinal surgery. Relationships between reported checklist use and mortality were determined using multivariable logistic regression and bootstrapped simulation. Results Of 12 296 patients included from 76 countries, 4843 underwent emergency laparotomy. After adjusting for patient and disease factors, checklist use before emergency laparotomy was more common in countries with a high Human Development Index (HDI) (2455 of 2741, 89.6 per cent) compared with that in countries with a middle (753 of 1242, 60.6 per cent; odds ratio (OR) 0.17, 95 per cent c.i. 0.14 to 0.21, P <0001) or low (363 of 860, 422 per cent; OR 008, 007 to 010, P <0.001) HDI. Checklist use was less common in elective surgery than for emergency laparotomy in high-HDI countries (risk difference -94 (95 per cent c.i. -11.9 to -6.9) per cent; P <0001), but the relationship was reversed in low-HDI countries (+121 (+7.0 to +173) per cent; P <0001). In multivariable models, checklist use was associated with a lower 30-day perioperative mortality (OR 0.60, 0.50 to 073; P <0.001). The greatest absolute benefit was seen for emergency surgery in low- and middle-HDI countries. Conclusion Checklist use in emergency laparotomy was associated with a significantly lower perioperative mortality rate. Checklist use in low-HDI countries was half that in high-HDI countries.Peer reviewe

Global variation in anastomosis and end colostomy formation following left-sided colorectal resection

Background End colostomy rates following colorectal resection vary across institutions in high-income settings, being influenced by patient, disease, surgeon and system factors. This study aimed to assess global variation in end colostomy rates after left-sided colorectal resection. Methods This study comprised an analysis of GlobalSurg-1 and -2 international, prospective, observational cohort studies (2014, 2016), including consecutive adult patients undergoing elective or emergency left-sided colorectal resection within discrete 2-week windows. Countries were grouped into high-, middle- and low-income tertiles according to the United Nations Human Development Index (HDI). Factors associated with colostomy formation versus primary anastomosis were explored using a multilevel, multivariable logistic regression model. Results In total, 1635 patients from 242 hospitals in 57 countries undergoing left-sided colorectal resection were included: 113 (6·9 per cent) from low-HDI, 254 (15·5 per cent) from middle-HDI and 1268 (77·6 per cent) from high-HDI countries. There was a higher proportion of patients with perforated disease (57·5, 40·9 and 35·4 per cent; P < 0·001) and subsequent use of end colostomy (52·2, 24·8 and 18·9 per cent; P < 0·001) in low- compared with middle- and high-HDI settings. The association with colostomy use in low-HDI settings persisted (odds ratio (OR) 3·20, 95 per cent c.i. 1·35 to 7·57; P = 0·008) after risk adjustment for malignant disease (OR 2·34, 1·65 to 3·32; P < 0·001), emergency surgery (OR 4·08, 2·73 to 6·10; P < 0·001), time to operation at least 48 h (OR 1·99, 1·28 to 3·09; P = 0·002) and disease perforation (OR 4·00, 2·81 to 5·69; P < 0·001). Conclusion Global differences existed in the proportion of patients receiving end stomas after left-sided colorectal resection based on income, which went beyond case mix alone

Uses of Antibiotics in Ornamental Fish in Hong Kong and the Antibiotic Resistance in the Associated Zoonotic Pathogens

The use of antibiotics in ornamental fish is not regulated, as they are not intended for human consumption. Although antibiotic resistant bacteria have been detected in ornamental fish worldwide, there have been no studies to look at the situation in Hong Kong. Therefore, the present study was conducted to investigate the use of antibiotics in ornamental fish. Ornamental fish were purchased from five local pet fish shops and the antibiotics in carriage water were quantified using liquid chromatography tandem mass spectrometry. Moreover, Aeromonas and Pseudomonas spp. present in carriage water were isolated and their minimum inhibitory concentrations against selected antibiotics were determined. Results indicated that among the twenty antibiotics screened, doxycycline (0.0155&ndash;0.0836 &micro;g L&minus;1), oxytetracycline (0.0102&ndash;29.0 &micro;g L&minus;1), tetracycline (0.0350&ndash;0.244 &micro;g L&minus;1), enrofloxacin (0.00107&ndash;0.247 &micro;g L&minus;1), and oxalinic acid (n.d.&minus;0.514 &micro;g L&minus;1) were detected in all sampled shops. Additionally, MIC results revealed that some of the Aeromonas and Pseudomonas spp. isolates were highly resistant to all antibiotics selected. Our findings confirmed that multiple antibiotics are being used in ornamental fish and the associated bacteria are resistant to selected antibiotics, suggesting that this could be a significant transmission route of antibiotic resistant bacteria to household indoor environments

One-Pot Tandem Photoredox And Cross-Coupling Catalysis With A Single Palladium Carbodicarbene Complex

The combination of conventional transition-metal-catalyzed coupling (2 e− process) and photoredox catalysis (1 e− process) has emerged as a powerful approach to catalyze difficult cross-coupling reactions under mild reaction conditions. Reported is a palladium carbodicarbene (CDC) complex that mediates both a Suzuki–Miyaura coupling and photoredox catalysis for C−N bond formation upon visible-light irradiation. These two catalytic pathways can be combined to promote both conventional transition-metal-catalyzed coupling and photoredox catalysis to mediate C−H arylation under ambient conditions with a single catalyst in an efficient one-pot process

Impact of Prophylactic Antibiotic Use in Ornamental Fish Tanks on Microbial Communities and Pathogen Selection in Carriage Water in Hong Kong Retail Shops

Antibiotics are routinely added to ornamental fish tanks for treating bacterial infection or as a prophylactic measure. However, the overuse or subtherapeutical application of antibiotics could potentially facilitate the selection of antibiotic resistance in bacteria, yet no studies have investigated antibiotic use in the retail ornamental fish sector and its impact on microbial communities. The present study analyzed the concentrations of twenty antibiotics in the carriage water (which also originates from fish tanks in retail shops) collected monthly from ten local ornamental fish shops over a duration of three months. The antibiotic concentrations were correlated with the sequenced microbial community composition, and the risk of resistance selection in bacteria was assessed. Results revealed that the detected concentrations of tetracyclines were the highest among samples, followed by fluoroquinolones and macrolides. The concentrations of oxytetracycline (44.3 to 2,262,064.2 ng L−1) detected across three months demonstrated a high risk for resistance selection at most of the sampled shops. Zoonotic pathogens (species of Rhodococcus, Legionella, and Citrobacter) were positively correlated with the concentrations of oxytetracycline, tetracycline, chlortetracycline, and enrofloxacin. This suggests that antibiotic use in retail shops may increase the likelihood of selecting for zoonotic pathogens. These findings shed light on the potential for ornamental fish retail shops to create a favorable environment for the selection of pathogens with antibiotics, thereby highlighting the urgent need for enhanced antibiotic stewardship within the industry

A Combined Experimental and Theoretical Study of the Versatile Reactivity of an Oxocerium(IV) Complex: Concerted Versus Reductive Addition

International audienceA combined experimental and theoretical investigation on the cerium(IV) oxo complex [(L-OEt)(2)Ce(=O)(H2O)].MeC(O)NH2 (1; L-OEt(-)=[Co(eta(5)-C5H5){P(O)(OEt)(2)}(3)](-)) demonstrates that the intermediate spin-state nature of the ground state of the cerium complex is responsible for the versatility of its reactivity towards small molecules such as CO, CO2, SO2, and NO. CASSCF calculations together with magnetic susceptibility measurements indicate that the ground state of the cerium complex is of multiconfigurational character and comprised of 74 % of Ce-IV and 26 % of Ce-III. The latter is found to be responsible for its reductive addition behavior towards CO, SO2, and NO. This is the first report to date on the influence of the multiconfigurational ground state on the reactivity of a metal-oxo complex

A Combined Experimental and Theoretical Study of the Versatile Reactivity of an Oxocerium(IV) Complex: Concerted Versus Reductive Addition

International audienceA combined experimental and theoretical investigation on the cerium(IV) oxo complex [(L-OEt)(2)Ce(=O)(H2O)].MeC(O)NH2 (1; L-OEt(-)=[Co(eta(5)-C5H5){P(O)(OEt)(2)}(3)](-)) demonstrates that the intermediate spin-state nature of the ground state of the cerium complex is responsible for the versatility of its reactivity towards small molecules such as CO, CO2, SO2, and NO. CASSCF calculations together with magnetic susceptibility measurements indicate that the ground state of the cerium complex is of multiconfigurational character and comprised of 74 % of Ce-IV and 26 % of Ce-III. The latter is found to be responsible for its reductive addition behavior towards CO, SO2, and NO. This is the first report to date on the influence of the multiconfigurational ground state on the reactivity of a metal-oxo complex