bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative survival and role of STS score in aortic paravalvular leak after SAVR or TAVR: a retrospective study from the USA
Authors: Padang Ratnasari , Ali Mahmoud , Greason Kevin L , Scott Christopher G , Indrabhinduwat Manasawee , Rihal Charanjit S , Eleid Mackram F , Nkomo Vuyisile T , Pellikka Patricia A , Pislaru Sorin V
Published: December 2018

Objective

The presence of aortic paravalvular leak (PVL) is associated with lower survival, but a direct comparison of its impact after transcatheter aortic valve replacement (TAVR) versus surgical aortic valve replacement (SAVR) has not been performed. This study sought to determine the differential influence of PVL on survival following TAVR versus SAVR and in patients with varying levels of risk as defined by the Society of Thoracic Surgeons (STS) risk score.

Methods

Patients with and without postprocedural PVL were identified from 2290 patients undergoing TAVR or SAVR at Mayo Clinic between 2008 and 2014. The primary endpoint was overall survival.

Results

There were 588 patients with PVL (374 TAVR, 214 SAVR): age 78±11 years, 63% male and mean follow-up of 3±2 years. PVL was trivial/mild in 442 (75%) patients. In propensity-matched analyses (n=86 per group), the overall survival at 1 and 4 years was 93% and 56% vs 89% and 61% in patients with PVL after TAVR versus SAVR, respectively (p=0.43). The presence or degree of PVL severity had no influence on survival of patients with high STS score (≥8%), while the presence of greater than mild PVL predicted worse survival in those with STS score <8%. During the first year after PVL diagnosis, while either improvement or stable PVL grade was seen in the majority of patients, worsening of PVL grade was more common in the TAVR group (19%) versus the SAVR group (4%) (p<0.0001).

Conclusions

At mid-term follow-up, the presence of PVL was associated with equally unfavourable outcomes following SAVR or TAVR. In patients with high STS risk score, the presence of PVL was not independently associated with increased mortality.
Evaluation of the safety of live attenuated influenza vaccine (LAIV) in children and adolescents with asthma and high-risk conditions: a population-based prospective cohort study conducted in England with the Clinical Practice Research Datalink
Authors: Caspard Herve , Steffey Amy , Mallory Raburn M , Ambrose Christopher S
Published: December 2018

Objectives

To assess the safety of live attenuated influenza vaccine (LAIV) in children in high-risk groups.

Design

Non-interventional cohort study.

Setting

England during 2013–2014 and 2014–2015 influenza seasons.

Participants

LAIV recipients identified from the Clinical Practice Research Datalink, aged 2–17 years, and with at least one underlying high-risk condition. LAIV recipients were matched with inactivated influenza vaccine (IIV) recipients and unvaccinated controls.

Primary outcome measures

Primary safety endpoints were any hospitalisation documented in the linked Hospital Episodes Statistics database within 42 days and up to 6 months after vaccination.

Results

11 463 children and adolescents were included: 4718 received the trivalent LAIV formulation during the 2013–2014 influenza season and 6745 received the quadrivalent formulation during the 2014–2015 influenza season. The risks of hospitalisation within 42 days were 231 per 1000 person-years (95% CI 193 to 275) in season 2013–2014 and 231 (95% CI 198 to 267) in season 2014–2015. These risks were not significantly different when compared with matched unvaccinated children (relative risks (RR) 0.96 (95% CI 0.78 to 1.19) in season 2013–2014, 0.90 (95% CI 0.76 to 1.07) in season 2014–2015) and consistently lower than after IIV administration (RR 0.47 (95% CI: 0.37 to 0.59) in season 2013–2014, 0.42 (95% CI 0.35 to 0.51) in season 2014–2015). A similar pattern was observed up to 6 months postvaccination with a risk of hospitalisation after LAIV administration that did not differ from what was observed in unvaccinated controls and was lower than after IIV administration.

Conclusions

This study did not identify new safety concerns associated with the administration of LAIV in children and adolescents with high-risk conditions. However, as with any other observational study, treatment administration was not randomly assigned and our findings may be confounded by differences between the groups at baseline.

Trial registration number

EUPAS18527.
Long-term urinary tract effect of ileal conduit after radical cystectomy compared with bladder preservation: a nationwide, population-based cohort study with propensity score-matching analysis
Authors: Liu Yu Liang , Luo Hao-Lun , Chiang Po-Huang , Chang Yen-Chen , Chiang Po-Hui
Published: December 2018

Objective

Ileal conduit urinary diversion (ICUD) is the most common procedure after radical cystectomy. Although complications have been reported, few patients with ICUD and bladder preservation controls have been available for long-term follow-up. This study compared the long-term effect of structural changes after cystectomy with ICUD to that in bladder preservation controls.

Design

A retrospective nationwide cohort study.

Setting

Data retrieved from the Taiwan National Health Insurance Research Database.

Participants

The National Health Insurance database was explored for patients diagnosed with bladder cancer between 1997 and 2006. Only cancer-free patients without chemotherapy and other types of urinary diversion who lived for >5 years were included in the analysis.

Outcome measures

Patient characteristics, comorbidity and postoperative urinary tract disease were statistically analysed and compared. Cox proportional hazards model was used to evaluate the incidence rates of outcomes after adjustment for covariates. Propensity scores analysis was used to balance the clinical parameters between groups. The primary outcomes were postoperative new-onset urinary tract disease such as urinary tract infection (UTI), UTI with septicaemia and chronic kidney disease (CKD), or calculus of kidney and ureter.

Results

There were 11 185 patients included in our cohort, among which 703 (6.3%) and 10 482 (93.7%) patients received ICUD and bladder preservation procedure, respectively. Compared with patients who only underwent a bladder preservation procedure, those who had undergone ICUD after cystectomy were independently associated with postoperative de novo urinary tract disease. Propensity score analysis (1:4) was also performed. ICUD contributed to significantly higher new-onset UTI, UTI with sepsis and CKD (HR=1.30, 3.16, 1.35, respectively) compared with bladder preservation procedure after adjustment for age, gender and comorbidities.

Conclusion

ICUD after radical cystectomy was associated with a higher incidence of UTI, UTI with septicaemia and CKD during long-term follow-up than the incidences following a bladder preservation procedure.
Metabolic syndrome is a sequela of radiation exposure in hypothalamic obesity among survivors of childhood brain tumors
Authors: Cooksey Raven , Wu Susan Y , Klesse Laura , Oden Jon D , Bland Ross E , Hodges Joseph C , Gargan Lynn , Vega Gloria Lena , Bowers Daniel C
Published: December 2018

Survivors of childhood brain tumors may be at risk for early onset of metabolic syndrome, possibly secondary to surgery and/or radiation exposure. This study examines effects of radiation exposure to hypothalamus-pituitary-adrenal axis (HPA) on metabolic risk among survivors of childhood brain tumors. One hundred forty-two met inclusion criteria; 60 had tumor surgery plus radiation exposure (>1 Gray (Gy)) to HPA. The second subgroup of 82 subjects had surgery only and were not exposed to radiation. Both subgroups had survived for approximately 5 years at the time of study. All had clinical evaluation, vital signs, anthropometry, measurement of body composition by dual X-ray absorptiometry and fasting laboratory assays (metabolic panel, insulin, C-peptide, insulin-like growth factor-1, leptin and adiponectin). Body composition data for both subgroups was compared with the National Health and Nutrition Survey (NHANES) subgroup of similar age, gender and body mass index. Cranial surgery was associated with obesity of similar severity in both subgroups. However, survivors exposed to radiation to the HPA also had increased visceral fat mass and high prevalence of growth hormone deficiency and metabolic syndrome. Fat mass alone did not explain the prevalence of the metabolic syndrome in radiation exposure subgroup. Other factors such as growth hormone deficiency may have contributed to metabolic risk. We conclude that prevalence of metabolic syndrome among subjects exposed to hypothalamic radiation was higher than expected from hypothalamic obesity alone. Radiation exposure may exert untoward endocrinopathies due to HPA exposure that worsens metabolic risk. Early screening for metabolic syndrome in this population is indicated.
Bariatric surgery among patients with heart failure: a systematic review and meta-analysis
Authors: Berger Sebastian , Meyre Pascal , Blum Steffen , Aeschbacher Stefanie , Ruegg Marco , Briel Matthias , Conen David
Published: December 2018

Background

Bariatric surgery reduces cardiovascular risk in obese patients. Heart failure (HF) is associated with an increased perioperative risk following bariatric surgery. This systematic review aimed to assemble the evidence on bariatric surgery in patients with known HF and the potential effect of bariatric surgery on incident HF in obese patients without prevalent HF.

Methods

We performed a comprehensive literature search up to 30 September 2017 and included studies comparing bariatric surgery to non-surgical treatment in patients with known presurgical HF. To assess whether bariatric surgery has any effect on incident HF, we also assembled studies looking at new-onset HF among patients without HF prior to surgery.

Results

We found five observational studies (0 randomised trials) comparing bariatric surgery with non-surgical treatment in patients with a diagnosis of HF prior to surgery. A review of the available studies (n=676 patients) suggested reduced admission rates for HF exacerbation and increased left ventricular ejection fraction after bariatric surgery. No meta-analysis was possible due to the heterogeneous nature of these studies. Seven studies (one randomised trial) reported data on new-onset HF in obese patients without HF prior to bariatric surgery (n=111 127 patients). When comparing surgical to non-surgical treatment groups, the pooled univariable and multivariable HRs for incident HF were 0.28 (95% CI 0.13 to 0.55) and 0.44 (95% CI 0.36 to 0.55), respectively.

Conclusion

In this systematic review, no randomised trial assessed the benefits and risks of bariatric surgery in obese patients with concomitant HF. Available studies do, however, show that surgery might prevent incident HF.
Poststroke seizure: optimising its management
Authors: Xu Michael Y
Published: December 2018

Seizure after stroke or poststroke seizure (PSS) is a common and very important complication of stroke. It can be divided into early seizure and late seizure, depending on seizure onset time after the stroke. It has been reported that ischaemic and haemorrhagic stroke accounts for about 11% of all adult epilepsy cases and 45% of epilepsy cases over 60 years of age. However, there are no reliable guidelines in clinical practice regarding most of the fundamental issues of PSS management. In recent years there has been an increased interest in the study of PSS which may give clinical practitioners a better picture of how to optimise PSS management. Studies have indicated two peaks in PSS occurrence—the first day and 6–12 months after a stroke. Haemorrhagic stroke, cortical involvement, severity of initial neurological deficit, younger patients (<65 years of age), family history of seizures and certain genetic factors carry a higher risk of PSS. The use of continuous electroencephalogram has demonstrated significant benefits in capturing interictal or ictal abnormalities, especially in cases of non-convulsive seizures and non-convulsive status epilepticus. Current available data indicated that there was no significant difference in antiepileptic efficacy among most of the antiepileptic drugs (AEDs) in PSS. Levetiracetam and lamotrigine are the most studied newer generation AEDs and have the best drug tolerance. The purpose of this review is to summarise the recent advances in PSS research and focus on the most important practice issues of PSS management.
Binormal Toeplitz operators on the Hardy space
Authors: Gu Caixing , Kang Dong-O , Ko Eungil , Lee Ji Eun
Published: December 2018

We characterize binormal Toeplitz operators with analytic, or, coanalytic symbol functions. Furthermore, for a large class of nonanalytic, noncoanalytic Toeplitz operators which include Toeplitz operators with trigonometric or rational symbols, we prove that those Toeplitz operators are binormal if and only if they are normal. Some of the historically important examples of Toeplitz operators in the paper show that our problem is subtle and the above result is sharp.
Addendum: “QCD parameters correlations from heavy quarkonia: αs(μ) from Mχ0c(0b) − Mηc(b) @ N2LO”
Authors: Narison Stephan
Published: December 2018

This note complements the original paper QCD Parameters Correlations from Heavy Quarkonia1 where, here, we present a more detailed discussion of the [Formula: see text]-results obtained @ N2LO for two different subtraction scales [Formula: see text] from the (pseudo)scalar heavy quarkonia mass-splittings [Formula: see text]. This complementary discussion is useful for a much better understanding of these results.
Certain functors of nilpotent Lie algebras with the derived subalgebra of dimension two
Authors: Johari Farangis , Niroomand Peyman
Published: December 2018

By considering the nilpotent Lie algebra with the derived subalgebra of dimension [Formula: see text], we compute some functors including the Schur multiplier, the exterior square and the tensor square of these Lie algebras. We also give the corank of such Lie algebras.
Non-Markovian Evolution: a Quantum Walk Perspective
Authors: Kumar N. Pradeep , Banerjee Subhashish , Srikanth R. , Jagadish Vinayak , Petruccione Francesco
Published: December 2018

Quantum non-Markovianity of a quantum noisy channel is typically identified with information backflow or, more generally, with departure of the intermediate map from complete positivity. But here, we also indicate certain non-Markovian channels that cannot be witnessed by the CP-divisibility criterion. In complex systems, non-Markovianity becomes more involved on account of subsystem dynamics. Here we study various facets of non-Markovian evolution, in the context of coined quantum walks, with particular stress on disambiguating the internal vs. environmental contributions to non-Markovian backflow. For the above problem of disambiguation, we present a general power-spectral technique based on a distinguishability measure such as trace-distance or correlation measure such as mutual information. We also study various facets of quantum correlations in the transition from quantum to classical random walks, under the considered non-Markovian noise models. The potential for the application of this analysis to the quantum statistical dynamics of complex systems is indicated.
Accelerator-Based Methods in Radio-Material 99Mo/99mTc Production Alternatives by Monte Carlo Method: The Scientific-Expedient Considerations in Nuclear Medicine
Authors: Khorshidi Abdollah
Published: December 2018

Some accelerator technologies are already used for commercial [Formula: see text]Mo-99mTc production, as the economic criteria are considered representative of the main differences between diverse technologies including accelerators and reactors. This study has provided a review of known and potential [Formula: see text]Mo production using conventional medical facilities. Accelerator-based method in 99mTc production via ([Formula: see text], [Formula: see text]) direct reaction on [Formula: see text]Mo was simulated using 18[Formula: see text]MeV proton beam. Meanwhile, a conceptual design for indirect [Formula: see text]Mo production via [Formula: see text]Mo([Formula: see text])[Formula: see text]Mo and [Formula: see text]Mo(n,[Formula: see text]2n)[Formula: see text]Mo reactions was investigated when an electron source of 35[Formula: see text]MeV by accelerator is used. These indirect reactions were explored via inserted [Formula: see text]Mo samples at different positions inside the lead region. Furthermore, Adiabatic Resonance Crossing (ARC) method based on proton accelerator via transmutation in [Formula: see text]Mo([Formula: see text]Mo was examined when the 30[Formula: see text]MeV proton beam is used. Saturation activity and yield were investigated using alternative proposed methods. The potential proliferation risk associated with accelerator technetium production is minimal. While accelerators could be turned into neutron sources which could in turn be used to irradiate [Formula: see text]U to breed plutonium, and centrifuges used to enrich [Formula: see text]Mo for targets could conceivably be turned to enriching uranium, this would result in very tiny global production capability particularly compared with research or power reactors. The potential of the fresh methods could provide a replacement or complement over current reactor-based supply sources in various radioisotopes production purposes.
Refinement of the Maxwell Formula for Fiber-Reinforced Composites
Authors: Kalamkarov Alexander , Andrianov Igor , Starushenko Galina
Published: December 2018

The effective properties of the fiber-reinforced composite materials with fibers of square cross-section are investigated. The novel formula for the effective coefficient of thermal conductivity refining the classical Maxwell formula (MF) is derived. The methods of asymptotic homogenization, boundary shape perturbation and Schwarz alternating process are applied. It is shown that the principal term of the asymptotic expansion of the refined formula in powers of small size of inclusions coincides with the classical MF. The corrections to the MF are obtained for different values of geometrical and physical properties of the constituents of the composite material. The analytical and numerical analyses are carried out and illustrated graphically. In particular, the derived refined formula and the MF are compared for the limiting values of the geometric dimensions and physical properties of the composite. It is shown that the refined formula is applicable for the inclusions with any conductivity in the entire range of the geometric sizes of inclusions, including the limiting cases of inclusions with zero thermal conductivity and maximally large inclusions.
Doxorubicin-Loaded CuS Nanoparticles Conjugated with GFLG: A Novel Drug Delivery System for Lymphoma Treatment
Authors: Jiang Ying , Guan Chaoyang , Liu Xu , Wang Yushan , Zuo Huaqin , Xia Tian , Xu Peipei , Ouyang Jian
Published: December 2018

Doxorubicin (DOX) plays an important part in lymphoma treatment. However, various side effects on normal tissues restrict its clinical use. Nanocarriers connected by Gly–Phe–Leu–Gly (GFLG) can be equipped with the advantages of nanoparticles (NPs), their enhanced permeability and retention (EPR) effect, and surface modifiability. Nanocarriers can also be specifically enzymatically hydrolyzed by cathepsin (Cath) B, a kind of enzyme highly expressed in tumor cells. In this work, we proposed a novel drug delivery system comprising GFLG conjugated with copper sulfide (CuS) NPs loaded with DOX. The system, designated as CuS-GFLG-DOX, could be used for NP-based targeted combination chemotherapy. Results showed that the drug delivery system had an appropriate diameter, good dispersibility, high encapsulation efficiency and high drug loading. The system also exhibited an excellent targeting of lymphoma cells and an enhanced antitumor activity. The possible pathway to induce cytotoxic effects was Bcl-2/caspase-mediated apoptosis pathway. In conclusion, CuS-GFLG-DOX could precisely deliver drugs to lymphoma cells and could be a novel and promising therapeutic option for lymphoma.
Existence and stability of invasion traveling waves for a competition system with random vs. nonlocal dispersals
Authors: Wang Jiao , Yu Zhixian , Meng Yanling
Published: December 2018

The purpose of this paper is to investigate asymptotic behaviors of the solutions for a competition system with random vs. nonlocal dispersal. We first prove the existence of invasion traveling waves via using the theory of asymptotic speeds of spread. Then we prove the invasion traveling waves are exponentially stable as perturbation in some exponentially weighted spaces by using the weighted energy and the squeezing technique.
Algebraic intersection spaces
Authors: Geske Christian
Published: December 2018

We define a variant of intersection space theory that applies to many compact complex and real analytic spaces [Formula: see text], including all complex projective varieties; this is a significant extension to a theory which has so far only been shown to apply to a particular subclass of spaces with smooth singular sets. We verify existence of these so-called algebraic intersection spaces and show that they are the (reduced) chain complexes of known topological intersection spaces in the case that both exist. We next analyze “local duality obstructions,” which we can choose to vanish, and verify that algebraic intersection spaces satisfy duality in the absence of these obstructions. We conclude by defining an untwisted algebraic intersection space pairing, whose signature is equal to the Novikov signature of the complement in [Formula: see text] of a tubular neighborhood of the singular set.
The Zariski topology graph on scheme
Authors: Aqalmoun Mohamed
Published: December 2018

Let [Formula: see text] be a quasi-compact scheme and [Formula: see text]. By [Formula: see text] and [Formula: see text], we denote the set of closed points of [Formula: see text] and the closure of the subset [Formula: see text]. Let [Formula: see text] be a nonempty subset of [Formula: see text]. We define the [Formula: see text]-Zariski topology graph on the scheme [Formula: see text], denoted by [Formula: see text], as an undirected graph whose vertex set is the set [Formula: see text], for two distinct vertices [Formula: see text] and [Formula: see text], there is an arc from [Formula: see text] to [Formula: see text], denoted by [Formula: see text], whenever [Formula: see text]. In this paper, we study the connectivity properties of the graph [Formula: see text], we establish the relationship between the connectivity of the graph [Formula: see text] and the structure of irreducible components of the scheme [Formula: see text]. Also, we characterize when the complement graph of the Zariski topology graph [Formula: see text] is a complete multipartite graph.
Cyclotomy and arithmetic properties of some families in Z[x]/〈xpq − 1〉
Authors: Jain Sonal , Batra Sudhir
Published: December 2018

Cyclotomic classes of order 2 with respect to a product of two distinct odd primes [Formula: see text] and [Formula: see text] are represented in some specific forms and using these forms an alternate proof of Theorem 3 of [C. Ding and T. Helleseth, New generalized cyclotomy and its applications, Finite Fields Appl. 4 (1998) 140–166] is given, when [Formula: see text]. Further, it is observed that these classes are related to [Formula: see text]-cyclotomic cosets, where [Formula: see text] and [Formula: see text] such that gcd([Formula: see text]. Finally, arithmetic properties of some families in [Formula: see text] and hence in [Formula: see text] are studied.
X-ray transmission and pXRF: implications for the analysis of geological samples through different media
Authors: Gazley Michael F. , Wellnitz Katrin
Published: December 2018

The fundamentals of X-ray physics are well understood, and many workers have commented on the poor performance and poor reproducibility of atomically-light elements by portable X-ray fluorescence (pXRF). However, the physics responsible for this is rarely discussed in the pXRF literature. Furthermore, it is well known that analysing samples through calico (cotton fabric) or paper bags results in lower concentrations reported by the pXRF instrument but, again, the physics of this is seldom discussed. This paper addresses these shortcomings by presenting X-ray transmission modelling and empirical data to show that the effects reported by many workers are entirely consistent with the physics of X-rays passing through matter, and thus that they are entirely predictable.
Characterizing the Security of the SMS Ecosystem with Public Gateways
Authors: Reaves Bradley , Vargas Luis , Scaife Nolen , Tian Dave , Blue Logan , Traynor Patrick , Butler Kevin R. B.
Published: December 2018

Recent years have seen the Short Message Service (SMS) become a critical component of the security infrastructure, assisting with tasks including identity verification and second-factor authentication. At the same time, this messaging infrastructure has become dramatically more open and connected to public networks than ever before. However, the implications of this openness, the security practices of benign services, and the malicious misuse of this ecosystem are not well understood. In this article, we provide a comprehensive longitudinal study to answer these questions, analyzing over 900,000 text messages sent to public online SMS gateways over the course of 28 months. From this data, we uncover the geographical distribution of spam messages, study SMS as a transmission medium of malicious content, and find that changes in benign and malicious behaviors in the SMS ecosystem have been minimal during our collection period. The key takeaways of this research show many services sending sensitive security-based messages through an unencrypted medium, implementing low entropy solutions for one-use codes, and behaviors indicating that public gateways are primarily used for evading account creation policies that require verified phone numbers. This latter finding has significant implications for combating phone-verified account fraud and demonstrates that such evasion will continue to be difficult to detect and prevent.
DLSpace
Authors: Sun Hui , Huang Jianzhong , Qin Xiao , Xie Changsheng
Published: December 2018

Due to limited numbers of program/erase cycles (i.e., P/Es) of NAND Flash, excessive out-of-place update and erase-before-write operations wear out these P/Es during garbage collections, which adversely shorten solid state disk (i.e., SSD) lifetime. The log space in NAND Flash space of an SSD performs as an updated page ′s buffer, which lowers garbage-collection frequency while reducing consumption of P/Es to extend SSD lifetime. In this article, we propose DLSpace, a novel distributed log space allocation strategy named
d
istributed
l
og
space
, which divides log space into block-level log space and page-level log space to significantly optimize SSD lifetime. DLSpace′s log page space is dedicated to data pages in a data block. Such log page space only buffers page-update operations in this data block; thereby the use of log blocks for postponing garbage collection delays. DLSpace is conducive to fully utilizing pages in data and log blocks to avoid erasures of blocks with free pages. Consequently, DLSpace decreases write amplification by reducing excessive valid page-rewrite and block-erase operations under random-write-intensive workloads. We carried out quantitative research on the extension of SSD lifetime by virtue of three metrics (i.e., write amplification, the number of block-erase operations, and the delay time before the first garbage collection occurring). Experimental results reveal that compared with the existing
t
raditional allocation strategy for
l
og
space
(i.e., TLSpace), DLSpace reduces write amplification and the number of erase operations by up to 55.2% and 64.1% to the most extent, respectively. DLSpace also extends TLSpace′s delay time of garbage collections by 73.3% to optimize SSD lifetime.
Scheduling Dynamic Parallel Workload of Mobile Devices with Access Guarantees
Authors: Anta Antonio Fernández , Kowalski Dariusz R. , Mosteiro Miguel A. , Wong Prudence W. H.
Published: December 2018

We study a dynamic resource-allocation problem that arises in various parallel computing scenarios, such as mobile cloud computing, cloud computing systems, Internet of Things systems, and others. Generically, we model the architecture as client mobile devices and static base stations. Each client “arrives” to the system to upload data to base stations by radio transmissions and then “leaves.” The problem, called
Station Assignment
, is to assign clients to stations so that every client uploads their data under some restrictions, including a target subset of stations, a maximum delay between transmissions, a volume of data to upload, and a maximum bandwidth for each station. We study the solvability of Station Assignment under an adversary that controls the arrival and departure of clients, limited to maximum rate and burstiness of such arrivals. We show upper and lower bounds on the rate and burstiness for various client arrival schedules and protocol classes. To the best of our knowledge, this is the first time that Station Assignment is studied under adversarial arrivals and departures.
Detailed heap profiling
Authors: Byma Stuart , Larus James R.
Published: December 2018

Modern software systems heavily use the memory heap. As systems grow more complex and compute with increasing amounts of data, it can be difficult for developers to understand how their programs actually use the bytes that they allocate on the heap and whether improvements are possible. To answer this question of heap usage efficiency, we have built a new, detailed heap profiler called Memoro. Memoro uses a combination of static instrumentation, subroutine interception, and runtime data collection to build a clear picture of exactly when and where a program performs heap allocation, and crucially
how
it actually uses that memory. Memoro also introduces a new visualization application that can distill collected data into
scores
and visual cues that allow developers to quickly pinpoint and eliminate inefficient heap usage in their software. Our evaluation and experience with several applications demonstrates that Memoro can reduce heap usage and produce runtime improvements of 10%.
OMR: out-of-core MapReduce for large data sets
Authors: Kaur Gurneet , Vora Keval , Koduru Sai Charan , Gupta Rajiv
Published: December 2018

While single machine MapReduce systems can squeeze out maximum performance from available multi-cores, they are often limited by the size of main memory and can thus only process small datasets. Our experience shows that the state-of-the-art single-machine in-memory MapReduce system Metis frequently experiences out-of-memory crashes. Even though today's computers are equipped with efficient secondary storage devices, the frameworks do not utilize these devices mainly because disk access latencies are much higher than those for main memory. Therefore, the single-machine setup of the Hadoop system performs much slower when it is presented with the datasets which are larger than the main memory. Moreover, such frameworks also require tuning a lot of parameters which puts an added burden on the programmer. In this paper we present OMR, an Out-of-core MapReduce system that not only successfully handles datasets that are far larger than the size of main memory, it also guarantees linear scaling with the growing data sizes. OMR actively minimizes the amount of data to be read/written to/from disk via on-the-fly aggregation and it uses block sequential disk read/write operations whenever disk accesses become necessary to avoid running out of memory. We theoretically prove OMR's linear scalability and empirically demonstrate it by processing datasets that are up to 5x larger than main memory. Our experiments show that in comparison to the standalone single-machine setup of the Hadoop system, OMR delivers far higher performance. Also in contrast to Metis, OMR avoids out-of-memory crashes for large datasets as well as delivers higher performance when datasets are small enough to fit in main memory.
Balanced double queues for GC work-stealing on weak memory models
Authors: Horie Michihiro , Horii Hiroshi , Ogata Kazunori , Onodera Tamiya
Published: December 2018

Work-stealing is promising for scheduling and balancing parallel workloads. It has a wide range of applicability on middleware, libraries, and runtime systems of programming languages. OpenJDK uses work-stealing for copying garbage collection (GC) to balance copying tasks among GC threads. Each thread has its own queue to store tasks. When a thread has no task in its queue, it acts as a thief and attempts to steal a task from another thread's queue. However, this work-stealing algorithm requires expensive memory fences for pushing, popping, and stealing tasks, especially on weak memory models such as POWER and ARM. To address this problem, we propose a work-stealing algorithm that uses double queues. Each GC thread has a public queue that is accessible from other GC threads and a private queue that is only accessible by itself. Pushing and popping tasks in the private queue are free from expensive memory fences. The most significant point in our algorithm is providing a mechanism to maintain the load balance on the basis of the use of double queues. We developed a prototype implementation for parallel GC in OpenJDK8 for ppc64le. We evaluated our algorithm by using SPECjbb2015, SPECjvm2008, TPC-DS, and Apache DayTrader.
Deep neural networks compiler for a trace-based accelerator (short WIP paper)
Authors: Chang Andre Xian Ming , Zaidy Aliasger , Burzawa Lukasz , Culurciello Eugenio
Published: December 2018

Deep Neural Networks (DNNs) are the algorithm of choice for image processing applications. DNNs present highly parallel workloads that lead to the emergence of custom hardware accelerators. Deep Learning (DL) models specialized in different tasks require a programmable custom hardware and a compiler/mapper to efficiently translate different DNNs into an efficient dataflow in the accelerator. The goal of this paper is to present a compiler for running DNNs on Snowflake, which is a programmable hardware accelerator that targets DNNs. The compiler correctly generates instructions for various DL models: AlexNet, VGG, ResNet and LightCNN9. Snowflake, with a varying number of processing units, was implemented on FPGA to measure the compiler and Snowflake performance properties upon scaling up. The system achieves 70 frames/s and 4.5 GB/s of off-chip memory bandwidth for AlexNet without linear layers on Xilinx’s Zynq-SoC XC7Z045 FPGA.
MakeCode and CODAL: intuitive and efficient embedded systems programming for education
Authors: Devine James , Finney Joe , de Halleux Peli , Moskal Michał , Ball Thomas , Hodges Steve
Published: December 2018

Across the globe, it is now commonplace for educators to engage in the making (design and development) of embedded systems in the classroom to motivate and excite their students. This new domain brings its own set of unique requirements. Historically, embedded systems development requires knowledge of low-level programming languages, local installation of compilation toolchains, device drivers, and applications. For students and educators, these requirements can introduce insurmountable barriers.

We present the motivation, requirements, implementation, and evaluation of a new programming platform that enables novice users to create software for embedded systems. The platform has two major components: 1) Microsoft MakeCode (
www.makecode.com
), a web app that encapsulates an entire beginner IDE for microcontrollers; and 2) CODAL, an efficient component-oriented C++ runtime for microcontrollers. We show how MakeCode and CODAL provide an accessible, cross-platform, installation-free programming experience for the BBC micro:bit and other embedded devices.
Transparent standby for low-power, resource-constrained embedded systems: a programming language-based approach (short WIP paper)
Authors: Sant'Anna Francisco , Sztajnberg Alexandre , de Moura Ana Lúcia , Rodrigues Noemi
Published: December 2018

Standby efficiency for connected devices is one of the priorities of the G20’s Energy Efficiency Action Plan. We propose transparent programming language mechanisms to enforce that applications remain in the deepest standby modes for the longest periods of time. We extend the programming language Céu with support for interrupt service routines and with a simple power management runtime. Based on these primitives, we also provide device drivers that allow applications to take advantage of standby automatically. Our approach relies on the synchronous semantics of the language which guarantees that reactions to the environment always reach an idle state amenable to standby. In addition, in order to lower the programming barrier of adoption, we show that programs in Céu can keep a sequential syntactic structure, even when applications require non-trivial concurrent behavior.
Statically relating program properties for efficient verification (short WIP paper)
Authors: Chimdyalwar Bharti , Darke Priyanka
Published: December 2018

Efficient automatic verification of real world embedded software with numerous properties is a challenge. Existing techniques verify a sufficient subset of properties by identifying implication relations between their verification outcomes. We believe this is expensive and propose a novel complementary approach called grouping. Grouping does not consider the verification outcomes but uses data and control flow characteristics of the program to create disjoint groups of properties verifiable one group at a time.We present three grouping techniques, a framework, and experiments over open source and industrial applications to support our thesis. The experiments show a high gain in performance of a few state-of-the-art tools. This led to the integration of grouping into the verification process of an automotive software manufacturer.
An open-source realtime computational platform (short WIP paper)
Authors: Mehrotra Pavan , Dasgupta Sabar , Robertson Samantha , Nuyujukian Paul
Published: December 2018

Systems neuroscience studies involving in-vivo models often require realtime data processing. In these studies, many events must be monitored and processed quickly, including behavior of the subject (e.g., movement of a limb) or features of neural data (e.g., a neuron transmitting an action potential). Unfortunately, most realtime platforms are proprietary, require specific architectures, or are limited to low-level programming languages. Here we present a hardware-independent, open-source realtime computation platform that supports high-level programming. The resulting platform, LiCoRICE, can process on order 10e10 bits/sec of network data at 1 ms ticks with 18.2 µs jitter. It connects to various inputs and outputs (e.g., DIO, Ethernet, database logging, and analog line in/out) and minimizes reliance on custom device drivers by leveraging peripheral support via the Linux kernel. Its modular architecture supports model-based design for rapid prototyping with C and Python/Cython and can perform numerical operations via BLAS/LAPACK-optimized NumPy that is statically compiled via Numba’s pycc. LiCoRICE is not only suitable for systems neuroscience research, but also for applications requiring closed-loop realtime data processing from robotics and control systems to interactive applications and quantitative financial trading.
Improving typeclass relations by being open
Authors: Martínez Guido , Jaskelioff Mauro , De Luca Guido
Published: December 2018

Mathematical concepts such as monads, functors, monoids, and semigroups are expressed in Haskell as typeclasses. Therefore, in order to exploit relations such as “every monad is a functor”, and “every monoid is a semigroup”, we need to be able to also express relations between typeclasses.

Currently, the only way to do so is using
superclasses
. However, superclasses can be problematic due to their closed nature. Adding a superclass implies modifying the subclass’ definition, which is either impossible if one does not own such code, or painful as it requires cascading changes and the introduction of boilerplate throughout the codebase.

In this article, we introduce
class morphisms
, a way to relate classes in an open fashion, without changing class definitions. We show how class morphisms improve the expressivity, conciseness, and maintainability of code. Further, we show how to implement them while maintaining canonicity and coherence, two key properties of the Haskell type system. Extending a typechecker with class morphisms amounts to adding an elaboration phase and is an unintrusive change. We back this claim with a prototype extension of GHC.
Lightweight Photovoltaic Composite Structure on Stratospheric Airships
Authors: Zhang Xinyun , Sun Kangwen , Xu Dongdong , Guo Shijun
Published: December 2018

A semirigid solar array is an efficient energy system on the surface of stratospheric airships for utilizing the solar energy, which we believe that it has succeeded in providing some impressive results for conceptual design. This paper developed a lightweight photovoltaic composite structure (LPCS) according to the characteristics of the stratospheric airship capsule. In order to improve the flexibility of the solar cell, we studied the mechanical properties in the different thicknesses of the honeycomb core for LPCS by FEM software and three‐point bending test, and we also launched experiments to measure the temperature difference between upper and lower surfaces of the LPCS test samples under different solar radiation flux conditions. The experimental data were examined to evaluate the mechanical properties and thermal insulation performances of LPCS. Considering the quality of the whole structure, the paper finally comes up with the conclusion of the optimal thickness of the honeycomb core with further detailed descriptions.
Catalyst-Free
In Situ
Carbon Nanotube Growth in Confined Space
via
High Temperature Gradient
Authors: Chen Chaoji , Chen Yanan , Zhu Shuze , Dai Jiaqi , Pastel Glenn , Yao Yonggang , Liu Dapeng , Wang Yanbin , Wan Jiayu , Li Teng , Luo Wei , Hu Liangbing
Published: December 2018

Carbonaceous materials, such as graphite, carbon nanotubes (CNTs), and graphene, are in high demand for a broad range of applications, including batteries, capacitors, and composite materials. Studies on the transformation between different types of carbon, especially from abundant and low-cost carbon to high-end carbon allotropes, have received surging interest. Here, we report that, without a catalyst or an external carbon source, biomass-derived amorphous carbon and defective reduced graphene oxide (RGO) can be quickly transformed into CNTs in highly confined spaces by high temperature Joule heating. Combined with experimental measurements and molecular dynamics simulations, we propose that Joule heating induces a high local temperature at defect sites due to the corresponding high local resistance. The resultant temperature gradient in amorphous carbon or RGO drives the migration of carbon atoms and promotes the growth of CNTs without using a catalyst or external carbon source. Our findings on the growth of CNTs in confined spaces by fast high temperature Joule heating shed light on the controlled transition between different carbon allotropes, which can be extended to the growth of other high aspect ratio nanomaterials.
Concealed Pulmonary Vein Bigeminy during Sinus Rhythm in Patients with Paroxysmal Atrial Fibrillation: A Useful Marker for Pulmonary Vein Firing
Authors: Hu Jiqiang , Kuang Wu , Cui Xiaoyun , Li Yan , Wu Yang , Lin Qian , Wang Xuan
Published: December 2018

Introduction. A concealed pulmonary vein (PV) bigeminy (cPVB) may be found in some patients with atrial fibrillation (AF) during sinus rhythm (SR). The aim of this study was to investigate whether the presence of cPVB during SR is associated with a higher PV firing. Methods and Results. Seven hundred seventy-six PVs (excluding 5 right middle PVs and 8 left common trunks) were mapped in 198 patients with paroxysmal AF (PAF) who underwent circumferential PV isolation. cPVB with a mean coupling interval of 136 ± 16 ms during SR was observed prior to ablation in 22 (11%) patients. Focal firing was provoked prior to ablation in 144 (19%) PVs. The incidence of focal firing was greater in PVs exhibiting cPVB compared with PVs without cPVB (89% vs. 16%; P<0.001). Also, the number of radiofrequency applications required for isolation was greater in ipsilateral PVs, exhibiting cPVB compared with ipsilateral PVs without cPVB (21.6 ± 6.8 vs. 18.2 ± 5.6; P=0.024). During a follow-up of 32 ± 20 months, the single ablation success rate was 82%. Compared with patients without cPVB, patients with cPVB were associated with higher recurrence rate of AF (27% vs. 17%; p=0.032). Conclusion. cPVB during SR was observed prior to index ablation in 11% of PAF patients. Such a potential itself may be a PV firing in a concealed manner, which does not reactivate LA. The PV exhibiting cPVB required a greater number of radiofrequency applications for isolation. Compared to patients without cPVB, the recurrence rate of AF in patients with cPVB was greater.
Security Vulnerabilities and Countermeasures for Time Synchronization in TSCH Networks
Authors: Yang Wei , Wan Yadong , He Jie , Cao Yuanlong
Published: December 2018

Time‐slotted channel hopping (TSCH), which can enable highly reliable and low‐power wireless mesh networks, is the cornerstone of current industrial wireless standards. In a TSCH network, all nodes must maintain high‐precision synchronization. If an adversary launches a time‐synchronization attack on a TSCH network, the entire network communication system can be paralyzed. Thus, time‐synchronization security is a key problem in this network. In this article, time synchronization is divided into single‐hop pairwise, clusterwise, and three‐level multihop according to the network scope. We deeply analyze their security vulnerabilities due to the TSCH technology itself and its high‐precision synchronization requirements and identify the specific attacks; then, we propose corresponding security countermeasures. Finally, we built a test bed using 16 OpenMoteSTM nodes and the OpenWSN software to evaluate the performance of the proposed scheme. The experimental results showed that serious security vulnerabilities exist in time‐synchronization protocols, and the proposed countermeasures can successfully defend against the attacks.