Static locality analysis for cache management

Most memory references in numerical codes correspond to array references whose indices are affine functions of surrounding loop indices. These array references follow a regular predictable memory pattern that can be analysed at compile time. This analysis can provide valuable information like the locality exhibited by the program, which can be used to implement more intelligent caching strategy. In this paper we propose a static locality analysis oriented to the management of data caches. We show that previous proposals on locality analysis are not appropriate when the proposals have a high conflict miss ratio. This paper examines those proposals by introducing a compile-time interference analysis that significantly improve the performance of them. We first show how this analysis can be used to characterize the dynamic locality properties of numerical codes. This evaluation show for instance that a large percentage of references exhibit any type of locality. This motivates the use of a dual data cache, which has a module specialized to exploit temporal locality, and a selective cache respectively. Then, the performance provided by these two cache organizations is evaluated. In both organizations, the static locality analysis is responsible for tagging each memory instruction accordingly to the particular type(s) of locality that it exhibits.Peer ReviewedPostprint (published version

Analysis of Self-Concept in Adolescents before and during COVID-19 Lockdown: Differences by Gender and Sports Activity

An appeal has been issued to the scientific community to investigate physical, mental and emotional states, and pro-social behaviours during the COVID-19 pandemic. Hence, this study aims to investigate adolescents’ self-concept before and during a lockdown period in relation to gender and type/amount of physical activity or sports. The pre-lockdown sample of 366 adolescents were aged 13–17 years (M = 15.51 ± 0.65), of whom 192 (52.5%) were females and 174 (47.5%) were males. During the lockdown, the age range of the sample was 13–17 years (M = 14.57 ± 1.47), of whom 82 (60.3%) were females, and 54 (39.7%) were males. The Form-5 Self-concept Questionnaire (AF-5) was used to measure adolescents’ self-concept. There was a reduction in adolescents’ overall self-concept during the COVID-19 pandemic, which was positively associated with emotional well-being, with family and peers being essential factors in the development of an appropriate self-concept. Furthermore, girls’ self-concept, especially academic self-concept, was higher than that of boys during the lockdown. However, both physical and emotional self-concept were higher for boys than girls before the COVID-19 lockdown, although no differences were found during the lockdown. The findings reveal that physical activity was positively correlated to self-concept before and during the COVID-19 lockdown

Novel post-processing procedure to enhance casting molds manufactured by binder jetting AM

The significant improvements made in additive manufacturing (AM) techniques since their beginnings, coupled with its intrinsic advantages, have resulted in a technology that stands out as most suitable for applications in leading sectors today. In addition to some of the properties of the parts, there are also some inherent aspects of AM techniques that hinder their applicability. In this respect, the application of calcium sulfate parts manufactured by binder jetting (BJ), as expendable casting elements, is limited by both the high quantity of volatile substances, due to the BJ process, and their low compression resistance. In this work, a novel part post-processing procedure is presented. This procedure consists of applying various heat treatments, in combination with a vacuum infiltration process using an Epsom salt solution. The procedure reduces the volatile content of BJ AM parts and enhances the compression strength with little modification to the part geometry. This post-processing substantially improves the applicability of BJ AM parts as expendable casting elements. After presenting this novel procedure and analyzing the significant enhancement of the properties of the AM calcium sulfate parts (i.e. permeability, the reduction of volatile content and reduction of compressive strength), a case study is presented with an expendable mold for aluminum casting. This procedure allows for a safer casting process, improves the part’s surface quality and reduces the internal porosity of the cast parts.S

Intravascular myopericytoma in the heel: Case report and literature review

Intravascular myopericytoma (IVMP), regarded as a variant of myopericytoma, is a rare tumor. Very few cases have been described, none in the foot. The first case of IVMP located in the heel of the foot is described in this article. A literature review is reported of all cases of IVMP published in the English literature. A 48-year-old man possessed an IVMP on the heel of the right foot. The physical examination and histopathological and ultrasound studies are described. The literature review yielded 5 cases of IVMP, 2 of which were in the thigh and 1 each in the oral mucosa, the periorbital region, and the leg. The possibility that these lesions may be malignant suggests that the histopathological study of vascular tumors should include immunohistochemical tests

Theoretical investigation of the eight low-lying electronic states of the cis- and trans-nitric oxide dimers and its isomerization using multiconfigurational second-order perturbation theory (CASPT2)

In this work we have carried out ab initio electronic structure calculations, CASSCF/CASPT2 and CASSCF/MRCI-SD+Q with several Pople's and correlation-consistent Dunning's basis sets, of the planar cis- and trans-NO dimers for the lowest eight electronic (singlet and triplet) states. The geometry, frequencies, dipole moment, binding energy, and vertical excitation energies are predicted with an accuracy close to or even better than the best reported ab initio previous results for some of these properties, and in very good agreement with the available experimental data. CASPT2 optimized geometries show the existence of at least four shallow NO-dimers (i.e., two cis-(NO)2 (1A1 and 3B2) and two trans-(NO)2 (1Ag and 3Au)), although CASSCF optimization with CASPT2 pointwise calculations indicate the existence of other less stable dimers, on the excited states. Vertical excitation energies were calculated for these four dimers. For the cis-NO dimer, the ordering and the energy spacings between the excited states (i.e., 1A1, 3B2, 1B2, 2nd 1A1, 1A2, 3A2, 3B1, 2nd 3B1) are very similar to those found in a recent MRCI-SD study. The singlet cis-NO dimer (1A1) is the most stable one in almost quantitative accord with the experimental data, and in disagreement with previous density functional theory studies. A nonplanar transition state for the singlet trans ↔ cis isomerization has also been fully characterized. This leads to an almost negligible energy barrier which would originate a rapid isomerization to the most stable cis-NO dimer at low temperatures, in accord with the experimental difficulties to measure the properties of the trans-NO dimer. Not only are basis set superposition error corrections necessary to evaluate accurately the binding energies, but also to determine the NN distance of these symmetrical dimers. Some problems regarding the symmetry of the wave function were found for the symmetrical NO dimers and for the NO+NO asymptote, and several approximate solutions were proposed

Ab initio 1A' ground potential energy surface and transition state theory kinetics study of the O(1D) + N2O → 2NO, N2 +O2(a1Δg) reactions

An ab initio study of the 1A' ground potential energy surface (PES) of the O(1D) + N2O(X1+) system has been performed at the CASPT2//CASSCF (complete active space second-order perturbation theory//complete active space self-consistent field) level with Pople basis sets. The two reactions leading to 2 NO(X2) [reaction (1)] and N2(X1g+) + O2(a1∆g) [reaction (2)] products have been investigated. In both reactions a trans-approach of the attacking oxygen to the N2O moiety is found to be preferred, more markedly in reaction (1). For this reaction also a cis-path is feasible and is possibly connected with the trans -path by a transition state placed below reactants. A thorough characterization of the entrance zone has been performed to allow for subsequent kinetics calculations. Fixed angle and minimum energy paths have been constructed and transition state geometries have been refined at the CASPT2 level, thus obtaining approximate structures and frequencies for the latter. From these calculations it can be inferred that both reactions proceed without an energy barrier. Rate constant calculations in the 100-1000 K temperature range based on CASPT2 structures and using the transition state theory yield values in good agreement with experiment for the two reactions, especially when a proper scaling of the energy barriers is performed. Also, for comparative purposes quasiclassical trajectory calculations were performed on reaction (1) in the same temperature range, using a previous pseudotriatomic analytical potential energy surface, obtaining good agreement with experiment

A new surgical procedure for hallux limitus treatment: Double-V osteotomy on the base of the proximal phalanx of the hallux

The purpose of this study was to evaluate the effectiveness of the new Double-V osteotomy of the first metatarsophalangeal joint (1 st MPJ) in patients with hallux limitus (HL). A study of 66 patients was performed, 33 patients were treated Cheilectomy and 33 were treated Double-V. All patients underwent an assessment of the passive mobility of the 1 st MPJ before the procedure, reevaluated 12 months later evaluating dorsiflexion, plantarflexion, and patients status using both the American Orthopaedic Foot and Ankle Society (AOFAS) for Hallux Metatarsophalangeal-Interphalangeal Scale. In comparing the improvement achieved regarding the increase of mobility obtained with surgical treatment, the feet operated with procedure Double-V gained significant degrees of movement increased in all analyzed parameters (P<.05). We achieved 13.33° more than average in dorsiflexion motion and 2.12° more than average in plantarflexion with regard to the feet that were operated with Cheilectomy procedure. Double-V scores on the AOFAS scale improved significantly (P=.000) 91.48 points postoperative, while with the following Cheilectomy only 79.30 points. This new surgical technique, easy to perform and with low complexity in surgical execution and a minimum of complications, produces better clinical and functional results that Cheilectomy alone

Runahead threads to improve SMT performance

In this paper, we propose Runahead Threads (RaT) as a valuable solution for both reducing resource contention and exploiting memory-level parallelism in Simultaneous Multithreaded (SMT) processors. Our technique converts a resource intensive memory-bound thread to a speculative light thread under long-latency blocking memory operations. These speculative threads prefetch data and instructions with minimal resources, reducing critical resource conflicts between threads. We compare an SMT architecture using RaT to both state-of-the-art static fetch policies and dynamic resource control policies. In terms of throughput and fairness, our results show that RaT performs better than any other policy. The proposed mechanism improves average throughput by 37% regarding previous static fetch policies and by 28% compared to previous dynamic resource scheduling mechanisms. RaT also improves fairness by 36% and 30% respectively. In addition, the proposed mechanism permits register file size reduction of up to 60% in a SMT processor without performance degradation.Peer ReviewedPostprint (published version

Uncertainty quantification and predictability of wind speed over the Iberian Peninsula

During recent decades, the use of probabilistic forecasting methods has increased markedly. However, these predictions still need improvement in uncertainty quantification and predictability analysis. For this reason, the main aim of this paper is to develop tools for quantifying uncertainty and predictability of wind speed over the Iberian Peninsula. To achieve this goal, several spread indexes extracted from an ensemble prediction system are defined in this paper. Subsequently, these indexes were evaluated with the aim of selecting the most appropriate for the characterization of uncertainty associated to the forecasting. Selection is based on comparison of the average magnitude of ensemble spread (ES) and mean absolute percentage error (MAPE). MAPE is estimated by comparing the ensemble mean with wind speed values from different databases. Later, correlation between MAPE and ES was evaluated. Furthermore, probability distribution functions (PDFs) of spread indexes are analyzed to select the index with greater similarity to MAPE PDFs. Then, the spread index selected as optimal is used to carry out a spatiotemporal analysis of model uncertainty in wind forecasting. The results indicate that mountainous regions and the Mediterranean coast are characterized by strong uncertainty, and the spread increases more rapidly in areas affected by strong winds. Finally, a predictability index is proposed for obtaining a tool capable of providing information on whether the predictability is higher or lower than average. The applications developed may be useful in the forecasting of wind potential several days in advance, with substantial importance for estimating wind energy production

Introducing runahead threads

Simultaneous Multithreading processors share their resources among multiple threads in order to improve performance. However, a resource control policy is needed to avoid resource conflicts and prevent some threads from monopolizing them. On the contrary, resource conflicts would cause other threads to suffer from resource starvation degrading the overall performance. This situation is especially sensitive for memory bounded threads, because they hold an important amount of resources while long latency accesses are being served. Several fetch policies and resource control techniques have been proposed to overcome these problems by limiting the per-thread resource utilization. Nevertheless, this limitation is harmful for memory bounded threads because it restricts the memory level parallelism available that hides the long latency memory accesses. In this paper, we propose Runahead threads on SMT scenarios as a valuable solution for both exploiting the memory-level parallelism and reducing the resource contention. This approach switches a memory-bounded eager resource thread to a speculative light thread, avoiding critical resource blocking among multiple threads. Furthermore, it improves the thread-level parallelism by removing long-latency memory operations from the instruction window, releasing busy resources. We compare an SMT architecture using Runahead threads (SMTRA) to both state-of-the-art static fetch and dynamic resource control policies. Our results show that the SMTRA combination performs better, in terms of throughput and fairness, than any of the other policies.Postprint (published version