Stability of Stretched Root Systems, Root Posets and Shards

Inspired by the infinite families of finite and affine root systems, we define a "stretching" operation on general crystallographic root systems which, on the level of Coxeter diagrams, replaces a vertex with a path of unlabeled edges. We embed a root system into its stretched versions using a similar operation on individual roots. For a fixed root, we describe the long-term behavior of two associated structures as we lengthen the stretched path: the downset in the root poset and Reading's arrangement of shards. We show that both eventually admit a uniform description, and deduce enumerative consequences: the size of the downset is eventually a polynomial, and the number of shards grows exponentially.

Output Voltage Ripple Reduction in a Symmetric Multistage-Stacked Boost Architecture (MSBA) Converter

This article proposes a different operation mode in a recently proposed converter, the multistage-stacked boost architecture (MSBA) converter working under the symmetric operation mode. The operation mode of the converter is analyzed with a modified pulse width modulation (PWM) scheme, in which the switching function of transistors is obtained from an interleaved scheme. The results show that the modified PWM results in a similar operation of the converter, with a reduced output voltage ripple, without increasing the switching frequency. A mathematical model of the converter is provided, the output voltage ripple calculation is performed in the traditional, and the modified PWM scheme, simulation, and experimental results are provided to verify the operation mode and the obtained equations.

Did Theresa May Kill the War Powers Convention? Comparing Parliamentary Debates on UK Intervention in Syria in 2013 and 2018

ABSTRACT This article asks whether Prime Minister Theresa May’s decision to bypass the House of Commons and order military action in Syria in 2018 killed the UK’s nascent War Powers Convention, established most visibly when MPs vetoed an essentially similar operation under Prime Minister David Cameron in 2013. It finds that the War Powers Convention survives, but in a weakened state, subject to new caveats that significantly narrow its scope. What happens next depends on the dynamic, unpredictable interaction between what future prime ministers believe, what strategic questions arise and what MPs will accept.

Performance Investigation of refrigerant R-407C as a Replacement to refrigerant R22 in Window Air Conditioner Unit

The present work deal with the experimental study to retrofit the refrigerant R407c with the refrigerant R22 in the air conditioning unit at an ambient temperature range between 30-45°C. The main component of the experimental rig includes a window air conditioner with a refrigeration capacity of 2 Ton refrigeration that used refrigerant R22 as a working fluid in the experimental work. The refrigerant R22 is replaced with refrigerant R407C due to similar operation properties for the two refrigerants. The experimental results displayed the refrigeration effect and coefficient of performance COP of the R22 system are high as with those of the R407C system. The falls in the evaporator and condenser for the R407C system is lower than that of the R22 system. The temperature of discharge in the compressor for the system of refrigerant R22 is greater than that of the R407C system. Moreover, condensation temperature along the tube of the condenser is decreased with the increase of the distance for both refrigerants. The refrigerant R407C may be selected as a good alternate for R22 with an agreement difference in the two refrigerants’ performance. The system did not require replacement for any part of the AC unit.

Treatment of choice for bicondylar tibial plateau fractures between open reduction with internal fixation versus hybrid circular external fixator: a systematic review

The high complication rate is closely related to the incidence of bicondylar tibial plateau fractures (BTPF) due to the involvement of the articular surface. The aim of this study is to compare open reduction with internal fixation (ORIF) and hybrid circular external fixation (HCEF) as the choice of surgical procedure for BTPF because these two procedures is still controversial until now. A systematic review using Cochrane library, PubMed, and Google Scholar was conducted based on PRISMA guideline. Inclusion criteria were studies comparing HCEF and ORIF of BTPF. Studies of only one surgical technique modality, schatzker types I-IV tibial plateau fractures, and case reports were excluded, resulting in six included studies. There is no significant difference in radiographs, functional and anatomical outcomes in both group (ORIF vs HCEF). Complications that measured are higher infection rate found in the ORIF group. Blood loss was higher in the ORIF group, while both procedures have similar operation time and functional outcome. The mean of hospital length of stay (LoS) seems to be higher 6.83 days (95%CI 0.96-12.70; P<0.00001) on ORIF group from the random effect of forest plot evaluation. According to this study, HCEF is more beneficial in terms of blood loss and hospital LoS. But overall ORIF and HCEF carry similar operation time, functional outcome, union rate, and complication.

Open Reduction with Internal Fixation (ORIF) versus Hybrid Circular External Fixator (HCEF) as the Treatment of Choice for Bicondylar Tibial Plateau Fractures : A Systematic Review and Meta-Analysis

Bicondylar Tibial Plateu Fractures (BTPF) present a challenge in management due to the involvement of articular surface, resulting in high complication rate. This study aims to compare two treatments, Open Reduction with Internal Fixation (ORIF) and Hybrid Circular External Fixation (HCEF) as the choice of surgical procedure for BTPF that still controversial until now. Discussion: BTPF is a complex and challenging injury associated with severe bone and soft tissue damage which may result in severe morbidity and chronic complications. The minimally invasive procedure offered by HCEF preserves soft tissue and offers lower rate of deep infection. Furthermore, HCEF should be more considered as the treatment of choice for BTPF due to its shorter hospital LoS which may minimalize nosocomial infection risks and costs. Materials and Methods: A systematic review using Cochrane Library, PubMed, and Google Scholar was conducted based on PRISMA guideline. Inclusion criteria were studies comparing HCEF and ORIF of BTPF. Studies of only one surgical technique modality, Schatzker types I-IV Tibial Plateu Fractures, and case reports were excluded, resulting in six included studies. For the meta-analysis of hospital length of stay (LoS), random effect model was used for continuous outcomes using Review Manager 5.3. Results: Most common complications are nerve injuries, infection, and non/delayed union. Blood loss was higher in ORIF group, while both procedures have similar operation time and functional outcome. The mean hospital LoS for ORIF (n = 60) was 18.45, as for HCEF (n =63) was 8.325. There was significant difference in terms of hospital LoS between ORIF and HCEF (P =0.003). Conclusion: ORIF and HCEF carry similar operation time, functional outcome, union rate, and complication, though HCEF is more beneficial in terms of blood loss and hospital LoS.

Optimising the Operation of Tidal Range Schemes

Marine renewable energy, including tidal renewable energy, is one of the less exploited sources of energy that could contribute to energy demand, while reducing greenhouse gas emissions. Amongst several proposals to build tidal range structure (TRS), a tidal lagoon has been proposed for construction in Swansea Bay, in the South West of the UK, but this scheme was recently rejected by the UK government due to the high electricity costs. This decision makes the optimisation of such schemes more important for the future. This study proposes various novel approaches by breaking the operation into small components to optimise the operation of TRS using a widely used 0-D modelling methodology. The approach results in a minimum 10% increase in energy output, without the inclusion of pumping, in comparison to the maximum energy output using a similar operation for all tides. This increase in energy will be approximately 25% more when pumping is included. The optimised operation schemes are used to simulate the lagoon operation using a 2-D model and the differences between the results are highlighted.

ASYNCHRONOUS INTRATECAL ANAESTHESIA IN SURGICAL TREATMENT OF ANAWAL HERNIA

In the main group (n = 20; 39.4 years ± 4.1 years; 71.4 kg ± 4.3 kg, I–II ASA) asynchronous intrathecal anaesthesia (AIA) 10 mg of hyperbaric bupivacaine in combination with 0.06 mg of buprenorphine was administered in patients with inguinal hernia repair. The control group (n = 20; 42.6 years ± 0.9 years; 75.4 kg ± 3.6 kg, I–II ASA) received synchronous intrathecal anaesthesia (SIA) 15 mg with isobaric bupivacaine in combination with 0.06 mg of buprenorphine during similar operation. The AIA and SIA provided effective pain relief for operations with long postoperative analgesia. In the AIA group, a hemodynamics was stable due to the lateral rather than bilateral sympathetic block, in contrast to the CIA. Improving the quality of analgesia allowed an early activation and enteral nutrition of patients, as well as a shortened rehabilitation period. An intrathecal administration of bupivacaine supplemented with buprenorphine was characterized by a significantly smaller number of negative side effects compared with the corresponding administration of other opioids.

Advancing System Performance with Redundancy: From Biological to Artificial Designs

Redundancy is a fundamental characteristic of many biological processes such as those in the genetic, visual, muscular, and nervous systems, yet its driven mechanism has not been fully comprehended. Until recently, the only understanding of redundancy is as a mean to attain fault tolerance, which is reflected in the design of many man-made systems. On the contrary, our previous work on redundant sensing (RS) has demonstrated an example where redundancy can be engineered solely for enhancing accuracy and precision. The design was inspired by the binocular structure of human vision, which we believe may share a similar operation. In this letter, we present a unified theory describing how such utilization of redundancy is feasible through two complementary mechanisms: representational redundancy (RPR) and entangled redundancy (ETR). We also point out two additional examples where our new understanding of redundancy can be applied to justify a system's superior performance. One is the human musculoskeletal system (HMS), a biological instance, and the other is the deep residual neural network (ResNet), an artificial counterpart. We envision that our theory would provide a framework for the future development of bio-inspired redundant artificial systems, as well as assist studies of the fundamental mechanisms governing various biological processes.

Engineering design of a grain silo and a bucket elevator for a combined unit for hopper preparation and seeding of grain crops

In this paper, we present the results of engineering design of components of a grain hopper and a bucket elevator for a combined unit for soil preparation and sowing of grain crops. The grain hopper has compartments for seeds and fertilizers. A coil-type metering device is also separated for seeds and fertilizers. The drive of the metering device for seeds and fertilizers is done by the rear wheels of the rolling device through a variator, which also serves to adjust seeds supply. On the same shaft with the metering device there is a sprocket, which transmits rotation moment to the bucket elevator through a chain of PR type. Due to special design characteristics of the grain hopper shape, seeds enter the coil type metering device by gravity. A similar operation is done for fertilizers. Portions of fertilizers and seeds fall into a small tank, joint for grain and fertilizers, from where the elevator's buckets deliver them to the distribution device. Seeds and fertilizer fall on the distributing device along the tray and then on rotating cone with blades, which uniformly distribute grain and fertilizers to all drill tubes. The developed units were organically included in the design of the entire combined unit. The obtained results allowed us to distinguish the following advantages of the developed designs of the hopper and the bucket elevator: a single metering unit for all sowing machines; easy access to the main units and mechanisms and their maintainability; ease of off-season maintenance; use of a large number of typical domestically produced units and mechanisms.