Diameters of Cocircuit Graphs of Oriented Matroids: An Update

Oriented matroids are combinatorial structures that generalize point configurations, vector configurations, hyperplane arrangements, polyhedra, linear programs, and directed graphs. Oriented matroids have played a key role in combinatorics, computational geometry, and optimization. This paper surveys prior work and presents an update on the search for bounds on the diameter of the cocircuit graph of an oriented matroid. The motivation for our investigations is the complexity of the simplex method and the criss-cross method. We review the diameter problem and show the diameter bounds of general oriented matroids reduce to those of uniform oriented matroids. We give the latest exact bounds for oriented matroids of low rank and low corank, and for all oriented matroids with up to nine elements (this part required a large computer-based proof). For arbitrary oriented matroids, we present an improvement to a quadratic bound of Finschi. Our discussion highlights an old conjecture that states a linear bound for the diameter is possible. On the positive side, we show the conjecture is true for oriented matroids of low rank and low corank, and, verified with computers, for all oriented matroids with up to nine elements. On the negative side, our computer search showed two natural strengthenings of the main conjecture are false.

1450 Relationship between Spinopelvic Parameters and Symptomatic Femoroacetabular Impingment: A Scoping Review

Aim Reports have shown that spinopelvic mobility influences the outcome following total hip arthroplasty. The aim of this scoping review was to investigate the relationship between spinopelvic parameters (SPP) and symptomatic femoroacetabluar impingement (FAI). Method A systematic computer search of EMBASE, PubMed and Cochrane for literature related to SPPs and FAI was undertaken as per PRISMA guidelines. Clinical outcome studies and prospective/retrospective studies that investigated the role of SPPs in symptomatic FAI were included. Review articles, case reports and book chapters were excluded. Information extracted pertained to symptomatic cam deformities, pelvic tilt, deviations in acetabular version, decreases in pain-free hip range of motion (ROM) on dynamic hip movements and radiological signs of FAI. Results The literature search identified 46 papers out of 1168 investigating the link between SPPs and pathological processes characteristic of FAI. Anteior pelvic tilt was associated with radiographic over-coverage parameters of FAI. Three studies associated FAI pathology with a greater pelvic incidence (PI), while four associated it with a smaller PI. In dynamic movements, decreased posterior pelvic tilt and reduced saggital pelvic ROM was found in symptomatic FAI patients during hip flexion. Conclusions Our study shows that spinopelvic parameters can influence radiological and clinical manifestations of FAI, with pelvic incidence, acetabular version and muscular imbalances being aetiologically implicated. Individual spinopelvic mobility may predispose to the development of FAI, which may be amenable to non-surgical management. If FAI pathoanatomy already exists however, sagittal pelvic parameters can influence whether FAI symptoms develop, and the extent to which they do so.

Efficacy and Safety of Butorphanol Use in Patient-Controlled Analgesia: A Meta-Analysis

Objective. This meta-analysis evaluates the efficacy and safety regarding usage of butorphanol in patient-controlled analgesia (PCA). Methods. Several databases such as PubMed, Cochrane Library, Embase, CNKI, and VIP were explored with the help of computer search and manual retrieval. Randomized controlled trial (RCT) was selected, and the meta-analysis was conducted using RevMan 5.1. The primary efficacy endpoint was the postoperative visual analog scale score, postoperative Ramsay sedation scale (RSS), and adverse events. Results. Nine RCTs met the inclusion criteria and were included in this meta-analysis. No significant differences were found between the butorphanol group and nonbutorphanol group at 12 h and 48 h. The postoperative RSS score at 12 h, 24 h, and 48 h was representative of the calming effect of butorphanol. No significant difference was found on the endpoint of the postoperative RSS score at 12 h, 48 h, and 24 h. The RSS score was lower in the butorphanol group in comparison to the nonbutorphanol group. The butorphanol group was also associated with lower rate of nausea, vomiting, itching, and dizziness compared to the nonbutorphanol group. Conclusion. Butorphanol may be used in PCA as a successful postoperative analgesia and is also associated with lower side effects. Further research is needed to verify the efficacy and safety of butorphanol.

Gait-assisted exoskeletons for children with cerebral palsy or spinal muscular atrophy: A systematic review

BACKGROUND: Cerebral Palsy (CP) and Spinal Muscular Atrophy (SMA) are common causes of motor disability in childhood. Gait exoskeletons are currently being used as part of rehabilitation for children with walking difficulties. OBJECTIVE: To assess the safety and efficacy and describe the main characteristics of the clinical articles using robot-assisted gait training (RAGT) with exoskeleton for children with CP or SMA. METHODS: A computer search was conducted in five bibliographic databases regarding clinical studies published in the last ten years. In order to be included in this review for further analysis, the studies had to meet the following criteria: (1) assess efficacy or safety of interventions; (2) population had to be children with CP or SMA aged between 3 and 14; (3) exoskeleton must be bilateral and assist lower limbs during walking. RESULTS: Twenty-one articles were selected, of which only five were clinical trials. 108 participants met the inclusion criteria for this study, all with a diagnosis of CP. The evidence level of the selected papers was commonly low. CONCLUSIONS: RAGT therapy seems to be safe for children with CP. However, further investigation is needed to confirm the results related to efficacy. There is no evidence of RAGT therapy for SMA children.

Search for antibacterial activity in a number of new S-derivatives (1,2,4-triazole-3(2H)-yl)methyl)thiopyrimidines

The relevance of the study of 1,2,4-triazole derivatives with pyrimidine fragment is due to the synthesis of potential broad-spectrum antibacterial drugs, low molecular weight inducers of interferon, and antitumor agents, search for molecular descriptors of their structure, important for establishing patterns “structure – biological activity”. The aim of the work is a computer search for the antibacterial action of new hybrids of 1,2,4-triazole-3(2H)-thiol with a pyrimidine fragment in relation to 5 test cultures, to establish the dependence of “structure – action”. Materials and methods. For an in-depth study of the antibacterial activity of derivatives of 1,2,4-triazole-3(2H)-thiol hybrids with a pyrimidine fragment, 4 test cultures of museum strains of gram-positive, gram-negative bacteria and one species of fungi were selected. In silico studies were performed using regression and classification QSAR models. Results. Derivatives of 1,2,4-triazole-3(2H)-thiol hybrids with a pyrimidine moiety showed high antibacterial activity against gram-negative microorganisms (E. coli, P. aeruginosa). The obtained experimental results allowed to establish not only the role of the main structural features of the compounds in the manifestation of antimicrobial properties, but also to evaluate the effectiveness of the created classification and regression QSAR models. Based on the presented parameters for individual predictive QSAR models, it is possible to conclude about the effectiveness, stability and feasibility of using these models to search for new S-derivatives (1,2,4-triazole-3(2H)-yl)methyl)thiopyrimidines as promising antimicrobial agents. Conclusions. It was found that the studied derivatives of hybrids of 1,2,4-triazole-3(2H)-thiol with a pyrimidine fragment showed high antibacterial activity against gram-negative microorganisms. The developed QSAR classification models based on the percentage of correctly predicted compounds (70 %) are the most effective in comparison with regression (50 %) for the search for new antimicrobial agents in a number of derivatives of hybrids 1,2,4 triazole-3(2H)-thiol with pyrimidine fragment.

SOLUTIONS TO A LEBESGUE–NAGELL EQUATION

We find all integer solutions to the equation $x^2+5^a\cdot 13^b\cdot 17^c=y^n$ with $a,\,b,\,c\geq 0$ , $n\geq 3$ , $x,\,y>0$ and $\gcd (x,\,y)=1$ . Our proof uses a deep result about primitive divisors of Lucas sequences in combination with elementary number theory and computer search.

Meta-Analysis of Clinical Efficacy and Safety of Tripterygium wilfordii Polyglycosides Tablets in the Treatment of Chronic Kidney Disease

Objective. Tripterygium wilfordii polyglycosides tablet (TGt) is an oral preparation extracted from plant Tripterygium wilfordii. It has the effects of anti-inflammation and inhibition of cellular and humoral immunity. However, many reports of adverse reactions caused by TGt have limited its application. In this paper, the clinical efficacy and safety of TGt in the treatment of chronic kidney disease (CKD) were verified by data mining and analysis, so as to provide theoretical data support for the application and development of TGt. Methods. A computer search of the following databases was conducted: PubMed, Web of Science, CBM, VIP, Wanfang Data, and CNKI. The search time limit is from the establishment of the database to September 2020. We searched for clinical randomized controlled trials of TGt in the treatment of CKD. The main types of CKD involved are nephrotic syndrome (NS), primary nephrotic syndrome (PNS), refractory nephrotic syndrome (RNS), and IgA nephropathy (IgAN). RevMan 5.2 and Stata 12.0 software were used to evaluate the literature quality and analyze the data. Finally, GRADEpro software was used to evaluate the quality of evidence. Results. According to the inclusion and exclusion criteria, 75 articles with a total of 6418 subjects were included. The results of the meta-analysis showed that TGt could reduce 24-hour urinary protein, increase serum albumin, improve clinical efficacy, and reduce disease recurrence rate in patients ( P < 0.05 ) with CKD compared with adrenocortical hormones or immunosuppressants. TGt could significantly reduce the level of serum creatinine (Scr) in patients with CKD ( P < 0.05 ), but it was not significant in reducing the level of blood urea nitrogen ( P > 0.05 ). In terms of safety evaluation, in patients with CKD, it could significantly reduce the incidence of gastrointestinal adverse reactions and neurogenic dizziness and headache ( P < 0.05 ). However, in terms of adverse reactions such as liver injury, respiratory infection, and leukopenia, TGt was as harmful as corticosteroids or immunosuppressants ( P < 0.05 ). The quality of the evidence was evaluated with GRADEpro software, and the results showed that TGt was strongly recommended for the treatment of CKD. Conclusion. TGt has certain efficacy in the treatment of CKD and has fewer side effects in certain types of diseases. The effect of TGt combined with other drugs is better than that of single use. This paper also has some limitations. Due to the limited number of the included studies, with all being from China, there may be methodological differences. Therefore, more high-quality literature data from different countries are needed.

High School to University: What Skills Do Students Need?

The problem of transferring library and information searching skills from high school to college is not new, but has become intensified in the last decade by the pressures of the information explosion, new technologies and budget reductions. While skills objectives for both high school and first year university are similar, the context and emphasis for the use of these skills differs in several respects. The survival skills students acquire in high school, particularly in the areas of periodical index use and computer search strategies, need to be expanded. Increased communication between high school teacher-librarians and academic librarians is recommended.

Surgical management of choroid plexus papilloma of the cerebellopontine and cerebellomedullary angle: classification and strategy

Choroid plexus papillomas (CPPs) are primary neuroectodermal neoplasms that usually arise in the fourth ventricle in adults. In this study, we present 12 patients with CPP arising from the cerebellopontine angle (CPP-CPA) and/or of the cerebellomedullary angle (CPP-CMA) that were treated in our department. Patients who underwent surgery for the treatment for CPP-CPA/CMA from January 2004 to March 2020 were identified by a computer search of their files from the Department of Neurosurgery, Tübingen. CPPs were classified according to their location into type 1 (tumor portion only in the CPA,), type 2 (tumor portions only in the CMA), and type 3 (tumor portions both in the CPA and CMA). Patients were evaluated for initial symptoms, previous therapies in other hospitals, extent of tumor resection, recurrence rate, and complications by reviewing patient documents. Of approximately 1500 CPA lesions, which were surgically treated in our department in the last 16 years, 12 patients (mean age 42 ± 19 years) were found to have CPP-CPA/CMA. Five were male, and seven were female patients. Gross total resection was achieved in nine cases, and a subtotal resection was attained in three cases. Tumor recurrence in the same location after the first surgery in our hospital was observed in 2 patients after 15 and 40 months of follow-up, and in another patient, distant metastases (C3/4 and L3 levels) were observed. Surgical removal of CPP is the treatment of choice, but additional therapeutic options may be necessary in case of remnant tumor portions, recurrence, or malignant transformation.