bluuebunny/crossref_metadata_2025_split huggingface dataset:
Explicit higher-order schemes for molecular dynamics problems
Authors: Ворожцов Е.В. , Киселев С.П. 
Published: August 2021

Рассмотрены явные симплектические разностные схемы Рунге–Кутты–Нистрема (RKN) с числом стадий от 1 до 5 для численного решения задач молекулярной динамики, описываемых системами с распадающимися гамильтонианами. Для числа стадий 2 и 3 параметры RKN-схем получены с помощью техники базисов Гребнера. Для числа стадий 4 и 5 новые схемы най дены с применением метода численной оптимизации Нелдера–Мида. В частности, для числа стадий 4 получены четыре новые схемы. Для числа стадий 5 получены три новые схемы в дополнение к четырем схемам, известным в литературе. Для каждого конкретного числа стадий найдена схема, являющаяся наилучшей с точки зрения минимума ведущего члена погрешности аппроксимации. Верификация схем осуществлена на задаче, имеющей точное решение. Показано, что симплектическая пятистадийная RKN-схема обеспечивает более точное сохранение баланса полной энергии системы частиц, чем схемы более низких порядков точности. Исследования устойчивости схем выполнены с помощью программного пакета Mathematica.
The Runge–Kutta–Nyström (RKN) explicit symplectic difference schemes are considered with a number of stages from 1 to 5 for the numerical solution of molecular dynamics problems described by systems with separable Hamiltonians. For the numbers of stages 2 and 3, the parameters of the RKN schemes are obtained using the Gröbner basis technique. For the number of stages 4 and 5, new schemes were found using the Nelder–Mead numerical optimization method. In particular, four new schemes are obtained for the number of stages 4. For the number of stages 5, three new schemes are obtained in addition to the four schemes, which are well-known in the literature. For each specific number of stages, a scheme is found being the best in terms of the minimum of the leading term of the approximation error. Verification of the schemes is carried out on a problem that has an exact solution. It is shown that the symplectic five-stage RKN scheme provides a more accurate conservation of the total energy balance of the particle system than schemes of lower orders of accuracy. The stability studies of the schemes were performed using the Mathematica software package.
A Multipole algorithm for solving a fractional generalization of the helmholtz equation
Authors: Белевцов Н.С. 
Published: August 2021

Рассматривается задача построения эффективного численного алгоритма решения дробно-дифференциального обобщения неоднородного уравнения Гельмгольца с дробной степенью оператора Лапласа. Построено мультипольное разложение, основанное на факторизации фундаментального решения рассматриваемого уравнения. Предложен способ нахождения значений функций Фокса, входящих в представленное мультипольное разложение. Разработана модификация мультипольного алгоритма для решения рассматриваемого дробно-дифференциального обобщения уравнения Гельмгольца. Приведены результаты вычислительных экспериментов, демонстрирующие эффективность предложенных алгоритмов.
The problem of constructing an efficient numerical algorithm for solving a fractional generalization of the Helmholtz equation with the fractional Laplacian is considered. A multipole expansion based on the factorized representation of the fundamental solution of the considered equation is constructed. A numerical method for computing the values of Fox H-functions from the multipole expansion is proposed. A modification of the multipole algorithm for solving the considered fractional generalization of the Helmholtz equation is developed. Numerical results demonstrating the efficiency of the proposed algorithms are discussed.
Iterative FFT-algorithms with high frequency resolution
Authors: Осипов О.В. 
Published: August 2021

В работе представлены три итерационных алгоритма быстрого преобразования Фурье с прореживанием по времени, имеющие алгоритмическую сложность O (N·R·log2N), где R — частотное разрешение спектральной характеристики (отношение длины набора частот к длине N набора отсчетов исходного сигнала). Алгоритмы отличаются способами организации вычислений: некоторые используют обратную перестановку битов, другие — дополнительные массивы. Приведены подробные вычислительные графы, а также блок-схемы разработанных алгоритмов. Полученные результаты можно использовать для улучшения отечественной электроники и программного обеспечения, а также включать в учебный процесс при подготовке инженеров в области цифровой обработки сигналов.
This paper presents three iterative algorithms for fast Fourier transform with decimation in time; these algorithms have the algorithmic complexity O (N·R·log2N), where R is the frequency resolution of the spectral characteristic (the ratio of the length of the frequency set to the length of the N set of samples of the source signal). The algorithms differ in the way they organize calculations: some use reverse bit permutation, while the others use additional arrays. Detailed computational graphs and flowcharts of the developed algorithms are provided. The results obtained can be used to improve domestic electronics and software as well as may be included in the training process for engineers in the field of digital signal processing.
High-performance computing platforms: current status and development trends
Authors: Антонов А.С. , Афанасьев И.В. , Воеводин Вл.В. 
Published: August 2021

В данной статье представлен обзор современного состояния суперкомпьютерной техники. Обзор сделан с разных точек зрения — начиная от особенностей построения современных вычислительных устройств до особенностей архитектуры больших суперкомпьютерных комплексов. В данный обзор вошли описания самых мощных суперкомпьютеров мира и России по состоянию на начало 2021 г., а также некоторых менее мощных систем, интересных с других точек зрения. Также делается акцент на тенденциях развития суперкомпьютерной отрасли и описываются наиболее известные проекты построения будущих экзафлопсных суперкомпьютеров.
This paper provides an overview of the current state of supercomputer technology. The review is done from different points of view — from the construction features of modern computing devices to the features of the architecture of large supercomputer complexes. This review includes descriptions of the most powerful supercomputers in the world and Russia since the early of 2021 as well as some less powerful systems that are interesting from other points of view. It also focuses on the development trends of the supercomputer industry and describes the most famous projects for building future exascale supercomputers.
Pengaruh Model Generative Learning (GL) terhadap Pemahaman Konsep Siswa pada Materi Kinematika
Authors: Sumarli Sumarli , Kusumawati Intan , Yanto Tedi 
Published: August 2021

<em>Penelitian ini bertujuan untuk mendeskripsikan pengaruh model Generative Learning (GL) terhadap pemahaman konsep siswa pada materi kinematika dan respon siswa terhadap Model GL yang diterapkan. Jenis penelitian ini adalah penelitian kuantitatif dengan metode pre-experimental design. Desain penelitian yang digunakan adalah one group pre-test – post-test design yang diterapkan pada satu kelompok. Populasi dalam penelitian ini adalah seluruh siswa kelas VIII di salah satu SMP Negeri Singkawang. Sampel penelitian ini adalah seluruh siswa kelas VIII A yang berjumlah 32 siswa. Pengambilan sampel dilakukan dengan menggunakan teknik purposive sampling. Instrumen yang digunakan berupa tes pemahaman konsep yang telah diuji validitasnya. Teknik analisis data untuk pengaruh Model GL terhadap pemahaman konsep siswa menggunakan MC Nemar dan angket respon siswa menggunakan persentase. Sebelum dilaksanakan penelitian, telah dilakukan uji coba. Berdasarkan hasil uji coba ditemukan bahwa rata-rata tingkat kesukaran sebesar 0,52 (sedang), daya pembeda sebesar 0,30 (cukup baik), validitas r<sub>hitung</sub> (0,44) &gt; r<sub>tabel</sub> (0,39) dengan kategori valid dan reabilitasnya sebesar 0,737 dengan kategori tinggi. Hasil analisis data dengan uji MC Nemar test dengan taraf signifikasi sebesar 5% diperoleh χ<sup>2</sup><sub>hitung </sub>&gt; χ<sup>2</sup><sub>tabel</sub> yaitu sebesar 4,764 &gt; 3,841, sehingga disimpulkan H<sub>a</sub> diterima dan H<sub>0</sub> ditolak yaitu terdapat pengaruh Model GL terhadap pemahaman konsep siswa pada materi kinematika gerak lurus. Analisis respon siswa yang diukur menggunakan lembar respon diperoleh tanggapan sebesar 86% terhadap penerapan model pembelajaran Generative Learning (GL) dengan katagori baik sekali.</em>
Reprise des échecs d’arthroplastie totale de cheville par arthrodèse tibiotalocalcanéenne à l’aide d’un enclouage centromédullaire rétrograde : à propos de sept cas
Authors: Hardy A. , Amouyel T. , Szymanski C. , Fontaine C. , Maynou C. 
Published: August 2021

Introduction: La difficulté des reprises chirurgicales des échecs d’arthroplastie totale de cheville (ATC) est multifactorielle, liée à l’importance de la perte de substance osseuse, à la qualité tégumentaire et à la déformation secondaire de l’arrière-pied. Elles peuvent consister en un rescellement prothétique ou une arthrodèse tibiotalienne ou tibiotalocalcanéenne (TTC). Nous rapportons une série de sept patients ayant bénéficié d’une arthrodèse TTC par clou centromédullaire rétrograde après échec d’ATC.Matériel et méthodes: Entre 2012 et 2017, sept échecs d’ATC ont bénéficié d’une arthrodèse TTC par enclouage rétrograde. Six femmes, un homme d’âge moyen 61,3 ans (52–77) ont été opérés suite à un descellement pour six patients et une infection pour un patient. La durée moyenne entre l’ATC et l’arthrodèse était de 9,2 ans (1,3–19). Une allogreffe était utilisée dans cinq cas, associée à une autogreffe dans deux cas. Un patient a bénéficié d’un espaceur en métal trabéculaire. Les variables cliniques étaient l’échelle visuelle analogique (EVA), l’évaluation de la satisfaction subjective, le score AOFAS et le score SF-36. Le bilan paraclinique se composait d’une radiographie standard en charge de face et de profil et d’un scanner en cas de suspicion de pseudarthrodèse.Résultats: Le suivi moyen était de 33,1 mois (6–72). Au dernier recul, l’EVA moyenne était de 3/10. Six patients se sont déclarés très satisfaits ou satisfaits. Le score AOFAS moyen était de 58,2 (51–66), le SF-36 physique de 33,5 et le SF-36 mental de 57,1. Le taux de fusion radiographique atteignait 86 % (6/7 chevilles) avec un délai moyen de 11,2 semaines (7–12). Une pseudarthrodèse sous-talienne confirmée au scanner a été reprise, aucune autre complication n’a été relevée.Discussion: Le taux de consolidation et les résultats cliniques sont satisfaisants chez les patients bénéficiant d’arthrodèse TTC par clou rétrograde après échec d’ATC. Dans les cas où l’articulation sous-talienne est arthrosique ou s’il existe une perte de substance osseuse massive, cette technique apparaît être la technique de référence.
Complications after 1002 endoscopic endonasal approach procedures at a single center: lessons learned, 2010–2018
Authors: Hardesty Douglas A. , Montaser Alaa , Kreatsoulas Daniel , Shah Varun S. , VanKoevering Kyle K. , Otto Bradley A. , Carrau Ricardo L. , Prevedello Daniel M. 
Published: August 2021

OBJECTIVE
The endoscopic endonasal approach (EEA) has evolved into a mainstay of skull base surgery over the last two decades, but publications examining the intraoperative and perioperative complications of this technique remain scarce. A prior landmark series of 800 patients reported complications during the first era of EEA (1998–2007), parallel to the development of many now-routine techniques and technologies. The authors examined a single-institution series of more than 1000 consecutive EEA neurosurgical procedures performed since 2010, to elucidate the safety and risk factors associated with surgical and postoperative complications in this modern era.

METHODS
After obtaining institutional review board approval, the authors retrospectively reviewed intraoperative and postoperative complications and their outcomes in patients who underwent EEA between July 2010 and June 2018 at a single institution.

RESULTS
The authors identified 1002 EEA operations that met the inclusion criteria. Pituitary adenoma was the most common pathology (n = 392 [39%]), followed by meningioma (n = 109 [11%]). No patients died intraoperatively. Two (0.2%) patients had an intraoperative carotid artery injury: 1 had no neurological sequelae, and 1 had permanent hemiplegia. Sixty-one (6.1%) cases of postoperative cerebrospinal fluid leak occurred, of which 45 occurred during the original surgical hospitalization. Transient postoperative sodium dysregulation was noted after 87 (8.7%) operations. Six (0.6%) patients were treated for meningitis, and 1 (0.1%) patient died of a fungal skull base infection. Three (0.3%) patients died of medical complications, thereby yielding a perioperative 90-day mortality rate of 0.4% (4 deaths). High-grade (Clavien-Dindo grade III–V) complications were identified after 103 (10%) EEA procedures, and multivariate analysis was performed to determine the associations between factors and these more serious complications. Extradural EEA was significantly associated with decreased rates of these high-grade complications (OR [95% CI] 0.323 [0.153–0.698], p = 0.0039), whereas meningioma pathology (OR [95% CI] 2.39 [1.30–4.40], p = 0.0053), expanded-approach intradural surgery (OR [95% CI] 2.54 [1.46–4.42], p = 0.0009), and chordoma pathology (OR [95% CI] 9.31 [3.87–22.4], p < 0.0001) were independently associated with significantly increased rates of high-grade complications.

CONCLUSIONS
The authors have reported a large 1002-operation cohort of EEA procedures and associated complications. Modern EEA surgery for skull base pathologies has an acceptable safety profile with low morbidity and mortality rates. Nevertheless, significant intraoperative and postoperative complications were correlated with complex intradural procedures and meningioma and chordoma pathologies.
Launching the Quality Outcomes Database Tumor Registry: rationale, development, and pilot data
Authors: Asher Anthony L. , Khalafallah Adham M. , Mukherjee Debraj , Alvi Mohammed Ali , Yolcu Yagiz U. , Khan Inamullah , Pennings Jacquelyn S. , Davidson Claudia A. , Archer Kristin R. , Moshel Yaron A. , Knightly John , Roguski Marie , Zacharia Brad E. , Harbaugh Robert E. , Kalkanis Steven N. , Bydon Mohamad 
Published: August 2021

OBJECTIVE
Neurosurgeons generate an enormous amount of data daily. Within these data lie rigorous, valid, and reproducible evidence. Such evidence can facilitate healthcare reform and improve quality of care. To measure the quality of care provided objectively, evaluating the safety and efficacy of clinical activities should occur in real time. Registries must be constructed and collected data analyzed with the precision akin to that of randomized clinical trials to accomplish this goal.

METHODS
The Quality Outcomes Database (QOD) Tumor Registry was launched in February 2019 with 8 sites in its initial 1-year pilot phase. The Tumor Registry was proposed by the AANS/CNS Tumor Section and approved by the QOD Scientific Committee in the fall of 2018. The initial pilot phase aimed to assess the feasibility of collecting outcomes data from 8 academic practices across the United States; these outcomes included length of stay, discharge disposition, and inpatient complications.

RESULTS
As of November 2019, 923 eligible patients have been entered, with the following subsets: intracranial metastasis (17.3%, n = 160), high-grade glioma (18.5%, n = 171), low-grade glioma (6%, n = 55), meningioma (20%, n = 184), pituitary tumor (14.3%, n = 132), and other intracranial tumor (24%, n = 221).

CONCLUSIONS
The authors have demonstrated here, as a pilot study, the feasibility of documenting demographic, clinical, operative, and patient-reported outcome characteristics longitudinally for 6 common intracranial tumor types.
Memory recovery in relation to default mode network impairment and neurite density during brain tumor treatment
Authors: Romero-Garcia Rafael , Suckling John , Owen Mallory , Assem Moataz , Sinha Rohitashwa , Coelho Pedro , Woodberry Emma , Price Stephen J. , Burke Amos , Santarius Thomas , Erez Yaara , Hart Michael G. 
Published: August 2021

OBJECTIVE
The aim of this study was to test brain tumor interactions with brain networks, thereby identifying protective features and risk factors for memory recovery after resection.

METHODS
Seventeen patients with diffuse nonenhancing glioma (ages 22–56 years) underwent longitudinal MRI before and after surgery, and during a 12-month recovery period (47 MRI scans in total after exclusion). After each scanning session, a battery of memory tests was performed using a tablet-based screening tool, including free verbal memory, overall verbal memory, episodic memory, orientation, forward digit span, and backward digit span. Using structural MRI and neurite orientation dispersion and density imaging (NODDI) derived from diffusion-weighted images, the authors estimated lesion overlap and neurite density, respectively, with brain networks derived from normative data in healthy participants (somatomotor, dorsal attention, ventral attention, frontoparietal, and default mode network [DMN]). Linear mixed-effect models (LMMs) that regressed out the effect of age, gender, tumor grade, type of treatment, total lesion volume, and total neurite density were used to test the potential longitudinal associations between imaging markers and memory recovery.

RESULTS
Memory recovery was not significantly associated with either the tumor location based on traditional lobe classification or the type of treatment received by patients (i.e., surgery alone or surgery with adjuvant chemoradiotherapy). Nonlocal effects of tumors were evident on neurite density, which was reduced not only within the tumor but also beyond the tumor boundary. In contrast, high preoperative neurite density outside the tumor but within the DMN was associated with better memory recovery (LMM, p value after false discovery rate correction [Pfdr] < 10−3). Furthermore, postoperative and follow-up neurite density within the DMN and frontoparietal network were also associated with memory recovery (LMM, Pfdr = 0.014 and Pfdr = 0.001, respectively). Preoperative tumor and postoperative lesion overlap with the DMN showed a significant negative association with memory recovery (LMM, Pfdr = 0.002 and Pfdr < 10−4, respectively).

CONCLUSIONS
Imaging biomarkers of cognitive recovery and decline can be identified using NODDI and resting-state networks. Brain tumors and their corresponding treatment affecting brain networks that are fundamental for memory functioning such as the DMN can have a major impact on patients’ memory recovery.
Incidence and risk factors for prolonged postoperative opioid use following lumbar spine surgery: a cohort study
Authors: Goyal Anshit , Payne Stephanie , Sangaralingham Lindsey R. , Jeffery Molly Moore , Naessens James M. , Gazelka Halena M. , Habermann Elizabeth B. , Krauss William , Spinner Robert J. , Bydon Mohamad 
Published: August 2021

OBJECTIVE
Sustained postoperative opioid use after elective surgery is a matter of growing concern. Herein, the authors investigated incidence and predictors of long-term opioid use among patients undergoing elective lumbar spine surgery, especially as a function of opioid prescribing practices at postoperative discharge (dose in morphine milligram equivalents [MMEs] and type of opioid).

METHODS
The OptumLabs Data Warehouse (OLDW) was queried for postdischarge opioid prescriptions for patients undergoing elective lumbar decompression and discectomy (LDD) or posterior lumbar fusion (PLF) for degenerative spine disease. Only patients who received an opioid prescription at postoperative discharge and those who had a minimum of 180 days of insurance coverage prior to surgery and 180 days after surgery were included. Opioid-naive patients were defined as those who had no opioid fills in 180 days prior to surgery. The following patterns of long-term postoperative use were investigated: additional fills (at least one opioid fill 90–180 days after surgery), persistent fills (any span of opioid use starting in the 180 days after surgery and lasting at least 90 days), and Consortium to Study Opioid Risks and Trends (CONSORT) criteria for persistent use (episodes of opioid prescribing lasting longer than 90 days and 120 or more total days’ supply or 10 or more prescriptions in 180 days after the index fill). Multivariable logistic regression was performed to identify predictors of long-term use.

RESULTS
A total of 25,587 patients were included, of whom 52.7% underwent PLF (n = 13,486) and 32.5% (n = 8312) were opioid-naive prior to surgery. The rates of additional fills, persistent fills, and CONSORT use were 47%, 30%, and 23%, respectively, after PLF and 35.4%, 19%, and 14.2%, respectively, after LDD. The rates among opioid-naive patients were 18.9%, 5.6%, and 2.5% respectively, after PLF and 13.3%, 2.0%, and 0.8%, respectively, after LDD. Using multivariable logistic regression, the following were identified to be significantly associated with higher risk of long-term opioid use following PLF: discharge opioid prescription ≥ 500 MMEs, prescription of a long-acting opioid, female sex, multilevel surgery, and comorbidities such as depression and drug abuse (all p < 0.05). Elderly (age ≥ 65 years) and opioid-naive patients were found to be at lower risk (all p < 0.05). Similar results were obtained on analysis for LDD with the following significant additional risk factors identified: discharge opioid prescription ≥ 400 MMEs, prescription of tramadol alone at discharge, and inpatient surgery (all p < 0.05).

CONCLUSIONS
In an analysis of pharmacy claims from a national insurance database, the authors identified incidence and predictors of long-term opioid use after elective lumbar spine surgery.
Intraarterial delivery of bevacizumab and cetuximab utilizing blood-brain barrier disruption in children with high-grade glioma and diffuse intrinsic pontine glioma: results of a phase I trial
Authors: McCrea Heather J. , Ivanidze Jana , O’Connor Ashley , Hersh Eliza H. , Boockvar John A. , Gobin Y. Pierre , Knopman Jared , Greenfield Jeffrey P. 
Published: August 2021

OBJECTIVE
Delivery of drugs intraarterially to brain tumors has been demonstrated in adults. In this study, the authors initiated a phase I trial of superselective intraarterial cerebral infusion (SIACI) of bevacizumab and cetuximab in pediatric patients with refractory high-grade glioma (diffuse intrinsic pontine glioma [DIPG] and glioblastoma) to determine the safety and efficacy in this population.

METHODS
SIACI was used to deliver mannitol (12.5 ml of 20% mannitol) to disrupt the blood-brain barrier (BBB), followed by bevacizumab (15 mg/kg) and cetuximab (200 mg/m2) to target VEGF and EGFR, respectively. Patients with brainstem tumors had a balloon inflated in the distal basilar artery during mannitol infusion.

RESULTS
Thirteen patients were treated (10 with DIPG and 3 with high-grade glioma). Toxicities included grade I epistaxis (2 patients) and grade I rash (2 patients). There were no dose-limiting toxicities. Of the 10 symptomatic patients, 6 exhibited subjective improvement; 92% showed decreased enhancement on day 1 posttreatment MRI. Of 10 patients who underwent MRI at 1 month, 5 had progressive disease and 5 had stable disease on FLAIR, whereas contrast-enhanced scans demonstrated progressive disease in 4 patients, stable disease in 2, partial response in 2, and complete response in 1. The mean overall survival for the 10 DIPG patients was 519 days (17.3 months), with a mean posttreatment survival of 214.8 days (7.2 months).

CONCLUSIONS
SIACI of bevacizumab and cetuximab was well tolerated in all 13 children. The authors’ results demonstrate safety of this method and warrant further study to determine efficacy. As molecular targets are clarified, novel means of bypassing the BBB, such as intraarterial therapy and convection-enhanced delivery, become more critical.
Clinical trial registration no.: NCT01884740 (clinicaltrials.gov)