Single versus bilateral chordo-papillary apparatus preservation in mitral valve replacement: a hemodynamic study

Background: It has been postulated that disruption of the mitral valve apparatus at the time of mitral valve replacement (MVR) is a risk factor for postoperative ventricular dysfunction. The aim of this study was to evaluate the effect of single versus bilateral chordo-papillary preservation on the left ventricular function in comparison to no preservation. Methods: This study was conducted from 2015 to 2018 on sixty patients who had MVR. The patients were classified into group I included 20 patients who underwent MVR with complete excision of the subvalvular chordae and tips of papillary muscles, group II: included 20 patients who underwent MVR with preservation of posterior chordo-papillary apparatus, and group III: included 20 patients who underwent MVR with preservation of both posterior and anterior chordo-papillary apparatus. Results: There were 20 males (33.3%), and the mean age was 48.76± 8.91 years. Patients in group III were significantly older (37.15 ±4.92, 39.8 ± 5.49, and 57.25 ± 6.93 years in groups I, II, and III, respectively; p< 0.001). The left ventricular end-diastolic (5.40 ±0.34, 4.96 ± 0.43, and 4.44 ± 0.55 mm in group I, II and III, respectively, p<0.001) and end-systolic diameter (4.33 ±0.48, 3.58 ±0.43 and 3.20 ±0.43 mm in group I, II and III; respectively, p<0.001) were significantly reduced in partial and complete preservation groups after 6 months. Left ventricular ejection fraction improved in the bilateral preservation and partial preservation groups after 6 months (45.32 ±9.78, 56.79 ±10.14, and 56.60 ±11.68 % in groups I, II and III respectively, p<0.001). Mechanical ventilation was significantly longer in group I (24.10 ± 6.6, 16.80 ± 5.97, and 15.80 ± 5.24 hours in groups I, II and III, respectively, p<0.001) and the duration of ICU stay was significantly longer in group I (78.65 ± 15.32, 65.40 ± 14.21, and 60.20 ± 12.58 hours in groups I, II and III, respectively, p<0.001). Conclusion: Preservation of the annulo-papillary continuity may preserve left ventricular geometry and performance. Total preservation of chordae could be superior to partial preservation with better left ventricular remodeling and improvement in the left ventricular functions

Deep Reinforcement Learning Powered IRS-Assisted Downlink NOMA

In this work, we examine an intelligent reflecting surface (IRS) assisted downlink non-orthogonal multiple access (NOMA) scenario with the aim of maximizing the sum rate of users. The optimization problem at the IRS is quite complicated, and non-convex, since it requires the tuning of the phase shift reflection matrix. Driven by the rising deployment of deep reinforcement learning (DRL) techniques that are capable of coping with solving non-convex optimization problems, we employ DRL to predict and optimally tune the IRS phase shift matrices. Simulation results reveal that IRS assisted NOMA based on our utilized DRL scheme achieves high sum rate compared to OMA based one, and as the transmit power increases, the capability of serving more users increases. Furthermore, results show that imperfect successive interference cancellation (SIC) has a deleterious impact on the data rate of users performing SIC. As the imperfection increases by ten times, the rate decreases by more than 10%

PHYSICIAN AS A MANAGER: PERSONAL AND MANAGERIAL CHARCTERISTICS, SAUDI ARABIA

BACKGROUND: The emergence of physicians' roles in key adminstrative positions within many King Saudi Arabia health care organizations has represented a major change in the medical profession over the last two decades. This have created a need for physicians who are willing to assume a high level of responsibility for managing evovling health care organizations. The study explores the perception of physician managers regarding their work, personal and managerial characteristics. METHODS: The data for this study were obtained from a sample of 200 physicians working in management positions in different health care organizations in Riyadh. Physicians were selected at random with probability proportional to size from a list containing managers in all health care organization to participate in the study RESULTS: Our results indicated that physician managers lack admistration skills. No formal training in medical adminstration and management because management principles are not integrated in the medical context and the majority were experienced in management for less than four years.  Very few possess the technical comptencies such as strategic planning, financial and economics knowledge. Boredom with medical practice, improvement of personal position and encouragement from others are related to being older, having more years in medicine and interest in medicine is reduced. The finding also supported the notion that physician manager can maintain stable levels of loyality to professional interest and organization. This dual commitment is related to work-relate characteristics involving sharing his time favorably to management job and to patient care. Recommendation: To improve their management skills physicians can benefit from mamagement education programs such as those offered by King Saud University

BIOPROCESIRANJE PRIRODNE FOSFATNE RUDE BAKTERIJOM STAPHYLOCOCCUS AUREUS

Phosphate ores are in high demand around the world because they are the primary raw materials used in the manufacturing of phosphatic fertilizers and other chemicals. Since the grade of the ore is gradually declining, it is becoming economically viable to mine and beneficiate numerous lower-grade deposits, and a significant number of precious minerals are discarded due to the inadequacy of new technological advances. Thus, biological processes are becoming more appealing in mineral processing due to their lower operating costs and potential applications to beneficiate low-grade complex ores through the interaction of bacteria and mineral surfaces, resulting in surface modification and mineral separation via bio-flotation. Staphylococcus aureus was supplied by the mineral bioprocessing lab, CMRDI. Bacterial adhesion measurements revealed a higher affinity for apatite than quartz. A binary mixture containing 12.5% P2O5 and 42.5% SiO2 yielded a concentrate containing 20.15% P2O5 and 33.5% SiO2. Using the bio-flotation process with Staphylococcus aureus and the optimal conditions on natural phosphate ore, a concentrate with 30.25% P2O5 was obtained from a feed containing 21.89% P2O5.Diljem svijeta velika je potražnja za fosfatnom rudom s obzirom na to da je riječ o primarnoj sirovini koja se koristi u proizvodnji fosfatnih gnojiva i drugih kemikalija. Budući da se koncentracija rude postupno smanjuje, ekonomski je sve isplativije eksploatirati i oplemenjivati brojna ležišta niže koncentracije s obzirom na to da se znatne količine korisne mineralne sirovine nedovoljno iskorištavaju zbog neadekvatnosti novih tehnologija. Stoga biološki procesi postaju sve zanimljiviji u oplemenjivanju SiO2 mineralnih sirovina zbog nižih operativnih troškova i potencijalne primjene za obogaćivanje kompleksnih ruda niskoga stupnja koncentracije, i to interakcijom bakterija i površine minerala, što rezultira površinskom modifikacijom i odvajanjem minerala putem bioflotacije. Bakteriju Staphylococcus aureus isporučio je laboratorij za bioprocesiranje minerala, CMRDI. Mjerenja bakterijske adhezije pokazala su veći afinitet za apatit nego za kvarc. Binarna smjesa koja je sadržavala 12,5 % P2O5 i 42,5 % SiO2 dala je koncentrat koji je sadržavao 20,15 % P2O5 i 33,5 % SiO2. Postupkom bioflotacije bakterijom Staphylococcus aureus pri optimalnim uvjetima na prirodnoj fosfatnoj rudi dobiven je koncentrat s 30,25 % P2O5 iz sirovine koja je sadržavala 21,89 % P2O5

DASS Good: Explainable Data Mining of Spatial Cohort Data

Developing applicable clinical machine learning models is a difficult task when the data includes spatial information, for example, radiation dose distributions across adjacent organs at risk. We describe the co-design of a modeling system, DASS, to support the hybrid human-machine development and validation of predictive models for estimating long-term toxicities related to radiotherapy doses in head and neck cancer patients. Developed in collaboration with domain experts in oncology and data mining, DASS incorporates human-in-the-loop visual steering, spatial data, and explainable AI to augment domain knowledge with automatic data mining. We demonstrate DASS with the development of two practical clinical stratification models and report feedback from domain experts. Finally, we describe the design lessons learned from this collaborative experience.Comment: 10 pages, 9 figure