bluuebunny/crossref_metadata_2025 huggingface dataset:
A tribal abstraction network for SNOMED CT target hierarchies without attribute relationships
Authors: Ochs Christopher , Geller James , Perl Yehoshua , Chen Yan , Agrawal Ankur , Case James T , Hripcsak George
Published: October 2014

Objective Large and complex terminologies, such as Systematized Nomenclature of Medicine–Clinical Terms (SNOMED CT), are prone to errors and inconsistencies. Abstraction networks are compact summarizations of the content and structure of a terminology. Abstraction networks have been shown to support terminology quality assurance. In this paper, we introduce an abstraction network derivation methodology which can be applied to SNOMED CT target hierarchies whose classes are defined using only hierarchical relationships (ie, without attribute relationships) and similar description-logic-based terminologies.

Methods We introduce the tribal abstraction network (TAN), based on the notion of a tribe—a subhierarchy rooted at a child of a hierarchy root, assuming only the existence of concepts with multiple parents. The TAN summarizes a hierarchy that does not have attribute relationships using sets of concepts, called tribal units that belong to exactly the same multiple tribes. Tribal units are further divided into refined tribal units which contain closely related concepts. A quality assurance methodology that utilizes TAN summarizations is introduced.

Results A TAN is derived for the Observable entity hierarchy of SNOMED CT, summarizing its content. A TAN-based quality assurance review of the concepts of the hierarchy is performed, and erroneous concepts are shown to appear more frequently in large refined tribal units than in small refined tribal units. Furthermore, more erroneous concepts appear in large refined tribal units of more tribes than of fewer tribes.

Conclusions In this paper we introduce the TAN for summarizing SNOMED CT target hierarchies. A TAN was derived for the Observable entity hierarchy of SNOMED CT. A quality assurance methodology utilizing the TAN was introduced and demonstrated.
A 29-year-old man with an unusual cause of an abscess
Authors: Vachhani Shivangi , Cioletti Anne
Published: October 2014

A 29-year-old man with no medical history presented with a left scalp abscess and left temporal oedema. He was initially started on treatment for community acquired Methicillin-resistantStaphylococcus aureuswith sulfamethoxazole and trimethoprim. Over the next 2 weeks, his swelling improved; however, he continued to have localised swelling and drainage from the area. Eventually, larvae of a botfly were removed from his scalp, and his symptoms resolved.
Transient ischaemic attack secondary to paraneoplastic erythrocytosis
Authors: Hurtarte Sandoval Aldo René , Flores Robles Bryan Josué , Andrus Robert Francis , Chon David Alejandro Yaxcal
Published: October 2014

A 67-year-old woman with a history of hypertension and type 2 diabetes mellitus was admitted to the hospital due to aphasia and left-sided hemiparesis during the past 5 h with resolution of symptoms within 24 h. On admission laboratory analysis showed haemoglobin 19.2 g/dL and haematocrit 55.1%. Cerebral CT scan was also performed on admission revealing periventricular leucoaraiosis. Studies to investigate the cause of erythrocytosis were started and elevated erythropoietin levels were found. In order to investigate a secondary cause of erythrocytosis an abdominal ultrasound was conducted revealing a left renal mass. CT scans of thorax, abdomen and pelvis confirmed renal mass 8×8 cm of diameter, suggestive of neoplasm without associated lymphadenopathy or metastases. Radical nephrectomy was performed and a pathological diagnosis demonstrated clear cell renal cell carcinoma and was staged as T2aN0M0.
Right ventricular cavity near obliteration in neonatal severe biventricular hypertrophic cardiomyopathy
Authors: Jivanji Salim GM , Daubeney Piers , Franklin Rodney , Sheppard Mary
Published: October 2014

A newborn presenting with cyanosis at day 9 of life was admitted to the local hospital. Initial local echocardiography confirmed a cardiac issue and the patient was transferred to a tertiary cardiac hospital. Further imaging confirmed a rare presentation of cardiomyopathy with severe right ventricular outflow tract obstruction. Surgery was performed but with postoperative haemodynamic instability complicated by incessant ventricular tachycardia. Following discussion with the family, care was withdrawn. Postmortem demonstrated a rare form of hypertrophic cardiomyopathy with right ventricular outflow tract obstruction not previously described in a neonate.
Subarachnoid haemorrhage and cerebral vasculopathy in a child with sickle cell anaemia
Authors: Inusa Baba , Casale Maddalena , Booth Caroline , Lucas Sebastian
Published: October 2014

Stroke in sickle cell anaemia (SCA) is either infarctive or haemorrhagic in nature. In childhood, over 75% of strokes in SCA are infarctive. We present an adolescent with SCA who developed hypertension at the age of 13, and was treated with lisinopril. Sixteen months later she was found in cardiorespiratory arrest and died on arrival in hospital. The last transcranial Doppler scan performed 6 months before her death and a brain MRI were reported normal. The autopsy discovered massive subarachnoid haemorrhage in association with vascular damage in the circle of Willis arteries. The case highlights a cause of haemorrhagic stroke, the first reported association between hypertension, SCA and a histopathologically proven cerebral vasculopathy. The difficulties in the management of haemorrhagic stroke and the poor outcome in SCA are discussed.
Add-on oral olanzapine worsens hallucinations in schizoaffective disorder
Authors: Volpe Umberto , Vignapiano Annarita , Gallo Olimpia , Fabrazzo Michele
Published: October 2014

Anecdotal evidence tends to favour olanzapine in the treatment of hallucinations in patients with schizophrenia spectrum disorders; however, no conclusive evidence is available on this topic. We report here a clinical case in which a 46-year-old man, suffering from a schizoaffective disorder (depressed type), underwent olanzapine treatment (20 mg/day). After inducing an initial amelioration, the patient had a re-exacerbation of auditory hallucinations and a clinical and psychosocial worsening, which subsided after olanzapine discontinuation. Olanzapine may induce a worsening of hallucinations in a psychotic disorder with substantial affective component and therefore its use should be carefully evaluated in such cases.
Mesenteric vein thrombosis caused by secondary polycythaemia from AndroGel
Authors: Katz Heather , Popov Eugene , Bray Natasha , Berman Barry
Published: October 2014

Mesenteric vein thrombosis is a rare but potentially lethal cause of abdominal pain. It is usually caused by prothrombotic states that can either be hereditary or acquired. Testosterone supplementation causes an acquired prothrombotic state by promoting erythropoeisis thus causing a secondary polycythaemia. We report a case of a 59-year-old man with a history of chronic obstructive pulmonary disease (COPD) stage III, who presented with abdominal pain. Evaluation revealed an elevated haemoglobin and haematocrit, a superior mesenteric vein thrombosis on CT and a negative Janus kinase 2 mutation. The patient is currently being treated with 6 months of anticoagulation with rivaroxiban. Although a well-known side effect of testosterone is thrombosis, the present case is used to document in the literature the first case of mesenteric vein thrombosis due to secondary polycythaemia from Androgel in the setting of COPD.
Surveillance colonoscopy in low-risk postpolypectomy patients: Is it necessary?
Authors: Hornung Thomas A , Bevan Roisin , Mumtaz Saqib , Hornung Benjamin R , Rutter Matthew D
Published: October 2014

Aim

Patients who have had colorectal adenomas removed are at increased risk of developing colorectal cancer in the future. We sought to determine whether surveillance colonoscopy at 5 years in low-risk postpolypectomy patients is necessary and effective.

Method

UK multicentre retrospective study. Patients diagnosed with ‘low-risk’ colorectal adenomas between April 2004 and April 2007 were identified and results of all subsequent lower gastrointestinal (GI) endoscopies were noted. Where no colonoscopy had been done at or after 5 years from the index investigation, patient details were cross-checked against hospital colorectal multidisciplinary team databases to ensure no colorectal cancer had been detected in the meantime.

Results

641 patients were included. 131 patients (20.4%) had a ‘per protocol’ surveillance colonoscopy at 5 years. Of these, no patients were found to have colorectal cancer, 10 patients (7.6%) had advanced adenomas, 26 patients (19.8%) had non-advanced adenomas and 95 patients (72.5%) had no further adenomas. 510 patients (79.6%) did not have a surveillance colonoscopy at 5 years. Of these, 110 patients (17.2%) developed lower GI symptoms within 5 years of their index endoscopy and underwent a further lower GI endoscopy to investigate these symptoms. 3 colorectal cancers in 3 patients were found during these endoscopies and two further colorectal cancers were found at symptomatic colonoscopies at or after 5 years from index.

Conclusions

Patients with low-risk adenomas should be risk profiled. Those with risk factors, such as two adenomas, male sex and advanced adenomas at index procedure should be offered 5-year surveillance colonoscopy.
Management of aneurysmal subarachnoid hemorrhage: a national survey of current practice
Authors: Al-Helli Othman , Bush Steven , Ingale Harshal , McConachie Norman
Published: October 2014

Objectives

The Royal College of Physicians and American Heart Association/American Stroke Association published recommendations in 2012 for the management of aneurysmal subarachnoid hemorrhage (aSAH). This was followed by recommendations included in the National Confidential Enquiry into Patient Outcome and Death (NCEPOD) report published in November 2013. The aim of this study was to assess how many of these recommendations were being followed across the UK and Ireland 6 months after publication of the latest recommendations, and to compare current practice with the NCEPOD data collected in 2011.

Methods

We formulated a survey composed of 19 questions regarding the management of aSAH, and conducted a telephone interview with the neurosurgical registrars on call.

Results

22 out of 30 centers aimed to treat ruptured aneurysms by coiling or clipping within 48 h from ictus, yet only 15 units offered regular weekend interventional neuroradiological treatment. In 9 units, all aSAH patients were routinely discussed in a multidisciplinary meeting.

Conclusions

At 6 months following publication of the NCEPOD report we found that in the majority of neurosurgical units, most of the key recommendations were being met. However, in the remainder there was variability in clinical practice.
Hemodynamic analysis of fast and slow aneurysm occlusions by flow diversion in rabbits
Authors: Chung Bongjae , Mut Fernando , Kadirvel Ramanathan , Lingineni Ravi , Kallmes David F , Cebral Juan R
Published: October 2014

Purpose

To assess hemodynamic differences between aneurysms that occlude rapidly and those occluding in delayed fashion after flow diversion in rabbits.

Methods

Thirty-six elastase-induced aneurysms in rabbits were treated with flow diverting devices. Aneurysm occlusion was assessed angiographically immediately before they were sacrificed at 1 (n=6), 2 (n=4), 4 (n=8) or 8 weeks (n=18) after treatment. The aneurysms were classified into a fast occlusion group if they were completely or near completely occluded at 4 weeks or earlier and a slow occlusion group if they remained incompletely occluded at 8 weeks. The immediate post-treatment flow conditions in aneurysms of each group were quantified using subject-specific computational fluid dynamics and statistically compared.

Results

Nine aneurysms were classified into the fast occlusion group and six into the slow occlusion group. Aneurysms in the fast occlusion group were on average significantly smaller (fast=0.9 cm, slow=1.393 cm, p=0.024) and had smaller ostia (fast=0.144 cm2, slow=0.365 cm2, p=0.015) than aneurysms in the slow occlusion group. They also had a lower mean post-treatment inflow rate (fast=0.047 mL/s, slow=0.155 mL/s, p=0.0239), kinetic energy (fast=0.519 erg, slow=1.283 erg, p=0.0468), and velocity (fast=0.221 cm/s, slow=0.506 cm/s, p=0.0582). However, the differences in the latter two variables were only marginally significant.

Conclusions

Hemodynamic conditions after flow diversion treatment of cerebral aneurysms in rabbits are associated with the subsequent aneurysm occlusion time. Specifically, smaller inflow rate, kinetic energy, and velocity seem to promote faster occlusions, especially in smaller and small-necked aneurysms. These results are consistent with previous studies based on clinical series.
Gene expression comparison of flow diversion and coiling in an experimental aneurysm model
Authors: Puffer Cole , Dai Daying , Ding Yong-Hong , Cebral Juan , Kallmes David , Kadirvel Ramanathan
Published: October 2014

Background and purpose

Mechanisms of both healing and complications, including spontaneous aneurysm rupture, remain unclear following flow diverter treatment. The aim of this study was to compare gene expression of various key molecules involved in the healing of aneurysms, between aneurysms treated with microcoils and flow diverters.

Methods

Saccular aneurysms were created in rabbits. Aneurysms were treated with coils (n=6) or flow diverters (n=6). Aneurysms were harvested at 4 weeks following treatment and used for gene expression and zymography experiments. Genes with a fold change of 1.2 or more were considered upregulated whereas those with a fold change of 0.8 or less were considered downregulated.

Results

All coil embolized aneurysms were completely occluded at follow-up. Two aneurysms were occluded and the remaining four samples were incompletely occluded in the flow diverter treated group. The following genes were expressed at lower levels in the flow diverter group compared with the coiled aneurysm group: proteinases (matrix metalloproteinases 2 and 9), cellular markers (endothelial nitric oxide synthase and smooth muscle actin), and structural proteins (collagens and fibronectin). Genes related to inflammation (tumor necrosis factor α and monocyte chemoattractant protein 1) were upregulated in flow diverter treated aneurysms compared with coil embolized aneurysms. Notably, the enzymatic activity of active matrix metalloproteinase 9 was high in aneurysms treated with flow diverters.

Conclusions

Our findings may provide improved understanding of rupture risk and healing following aneurysm treatment and inform development of therapies aimed at lowering rupture risk and accelerating healing.
Republished: Tracing PAKs from GI inflammation to cancer
Authors: Dammann Kyle , Khare Vineeta , Gasche Christoph
Published: October 2014

P-21 activated kinases (PAKs) are effectors of Rac1/Cdc42 which coordinate signals from the cell membrane to the nucleus. Activation of PAKs drive important signalling pathways including mitogen activated protein kinase, phospoinositide 3-kinase (PI3K/AKT), NF-κB and Wnt/β-catenin. Intestinal PAK1 expression increases with inflammation and malignant transformation, although the biological relevance of PAKs in the development and progression of GI disease is only incompletely understood. This review highlights the importance of altered PAK activation within GI inflammation, emphasises its effect on oncogenic signalling and discusses PAKs as therapeutic targets of chemoprevention.
Black holes and supersymmetry
Authors: Andrianopoli Laura , D'Auria Riccardo , Ferrara Sergio
Published: October 2014

Some aspects of black holes in supersymmetric theories of gravity are reviewed and some recent results outlined.
Probing space–time noncommutativity in the top quark pair production at e+e- collider
Authors: Manohar Ravi S. , Selvaganapathy J. , Das Prasanta Kumar
Published: October 2014

The forward–backward asymmetry observed in the top quark pair production at the Fermilab Tevatron points toward the existence of beyond the standard model physics. We have studied the top quark pair production [Formula: see text] in the TeV energy electron–positron linear collider to the leading order of the noncommutative parameter Θμν in the noncommutative standard model. We have made a detailed laboratory frame analysis of the time-averaged cross-section, polar, azimuthal angular distributions, transverse momentum and rapidity distributions, polar (forward–backward) and azimuthal asymmetries of the top-quark pair production in the presence of earth's rotation. We investigated their dependence on the orientation angle of the noncommutative vector η and the noncommutative scale Λ and found that those deviates from the standard model distributions significantly. The azimuthal distribution which is flat in the standard model deviates largely for η = π/2 and Λ = 700 GeV at the fixed machine energy E com = 1000 GeV . We found that the polar distribution deviates largely from the standard model distribution for η = π/2 and Λ = 500 GeV . The azimuthal asymmetry Aϕ which is zero in the standard model can be as large as 4% for Λ = 500 GeV and η = π/2 at the fixed machine energy E com = 1000 GeV . Assuming that the future TeV linear collider will observe Aϕ = ±0.01 we find Λ≤750(860) GeV corresponding to η = π/2. Similarly, corresponding to polar asymmetry A FBz = 0.5078 (which deviates from the standard model prediction by 1%), we find Λ≤760 GeV at the fixed machine energy E com = 1000 GeV for η = π/2.
Mechanical, spin polarized electronic and magnetic properties of TmX(X = Cu, Ag): First principle study
Authors: Chand Satish , Singh R. P. , Govindan A. , Singh S. K.
Published: October 2014

To study the mechanical, spin polarized electronic and magnetic behavior of TmX (X = Cu, Ag) , full-potential linear augmented plane wave plus local orbital method has been used. The lattice parameter (a0), bulk modulus (B0) and its first-order pressure derivative [Formula: see text] have been calculated using optimization method. Mechanical properties have been studied in terms of elastic constants (Cij), Young's modulus (Y), shear modulus (G) and Poisson's ratio (v) at ambient temperature and pressure which are found to be consistent with available experimental/theoretical values. Electronic properties have been investigated in terms of band structure and density of state histograms for spin up and spin down channel. Electronic and magnetic behavior of TmX shows that studied materials are metallic ferromagnets with high spin polarization in which Tm-f state electrons are contributed mainly.
Exact solutions of three-dimensional black holes: Einstein gravity versus F(R) gravity
Authors: Hendi S. H. , Eslam Panah B. , Saffari R.
Published: October 2014

In this paper, we consider Einstein gravity in the presence of a class of nonlinear electrodynamics, called power Maxwell invariant (PMI). We take into account (2 + 1)-dimensional spacetime in Einstein-PMI gravity and obtain its black hole solutions. Then, we regard pure F(R) gravity as well as F(R)-conformally invariant Maxwell (CIM) theory to obtain exact solutions of the field equations with black hole interpretation. Finally, we investigate the conserved and thermodynamic quantities and discuss about the first law of thermodynamics for the mentioned gravitational models.
First principle calculations of hydrogen sulfide adsorption and dissociation on pure Pd (111) and Au (111), and alloy Pd/Au (111) and Au/Pd (111) surfaces
Authors: Liu Na , Wang Xue-Ye , Wan Ya-Li
Published: October 2014

The hydrogen sulfide adsorption and dissociation on pure Pd (111) and Au (111), alloy Pd / Au (111) and Au / Pd (111) surfaces have been investigated using the pseudo-potential plane wave method within the generalized-gradient approximation density functional theory (GGA+DFT). The results show that H 2 S tends to be adsorbed on top site, HS prefers to locate on bridge site, and the S and H locate on fcc site on various surfaces. Compared the adsorption of sulfur-containing species and hydrogen on pure and alloy metal surfaces, a similar trend of adsorption energies on the metal surfaces ( Pd / Au (111) > Pd (111) > Au (111) > Au / Pd (111)) is found. In addition, the dissociation process on the Pd (111) and Pd / Au (111) surfaces is predicted to be exothermic. However, on Au (111) and Au / Pd (111), the dissociation process is endothermic. The work reveals that H 2 S dissociation is more likely to happen on Pd / Au (111) surface. Finally, the adsorption energies of adsorbate on metal surfaces have strong correlation with the d-band center. The d-band center moves away from the Fermi level, and the adsorption energy decreases. According to the LDOS analysis, the inner Au atoms of Pd / Au (111) can enhance the top-layer d-band intensity, whereas the inner Pd atoms of Au / Pd (111) cause the opposite effect. The further electronic state analysis reveals the interaction between H 2 S and metal surfaces.
NUMERICAL ANALYSIS OF ELECTROMAGNETO-MECHANICAL COUPLING USING LAGRANGIAN APPROACH AND ADAPTIVE TIME STEPPING METHOD
Authors: LI WEIXIN , DONG HAIJIE , YUAN ZHENSHENG , CHEN ZHENMAO
Published: October 2014

Electromagneto-mechanical coupling effect associated with vibration induced eddy currents plays an important role in the evaluation and design of many magnetic devices, such as a tokamak. In this paper, a updated Lagrangian formulation for eddy current analysis of deformable bodies was presented through transformation from reference configuration to current configuration. A coupled analysis method based on Lagrangian meshes and Ar method was developed. A corresponding code was developed and verified by simulating Team Problem 16. The numerical method was further updated by introducing an adaptive time stepping procedure to improve its simulation efficiency.
STEADY-STATE RESPONSE OF PIPES CONVEYING PULSATING FLUID NEAR A 2:1 INTERNAL RESONANCE IN THE SUPERCRITICAL REGIME
Authors: ZHANG YAN-LEI , CHEN LI-QUN
Published: October 2014

The work investigates steady-state responses of a pipe conveying fluid with a harmonic component of flow speed superposed on a constant mean value in the supercritical regime. If the flow speed exceeds a critical value, the straight configuration of the pipe becomes unstable and bifurcates into two stable curved configurations. The transverse motion measured from each of the curved equilibrium configurations is governed by a nonlinear integro-partial-differential equation. The Galerkin method is employed to discretize the governing equation into a set of coupled nonlinear ordinary differential equations with gyroscopic terms. For the pipes in the supercritical regime, the method of multiple scales is used to determine the steady-state in the vicinity of two-to-one resonance. In the presence of the internal resonance, the subharmonic, the superharmonic and the summation, and the difference resonances exist due to the pulsating fluid. The amplitude–frequency relationships are established with the emphasis on the effects of the viscosity, the pulsating amplitude, the nonlinearity, and the mean flow speed. Some nonlinear phenomena such as the appearance of the peak or jumps pertaining to modal interaction are demonstrated. The numerical integration results are in agreement with the analytical predictions.
Evaluation of the moisture content of tapioca starch using near-infrared spectroscopy
Authors: Phetpan Kittisak , Sirisomboon Panmanas
Published: October 2014

The purpose of this study was to develop a calibration model to evaluate the moisture content of tapioca starch using the near-infrared (NIR) spectral data in conjunction with partial least square (PLS) regression. The prediction ability was assessed using a separate prediction data set. Three groups of tapioca starch samples were used in this study: tapioca starch cake, dried tapioca starch and combined tapioca starch. The optimum model obtained from the baseline-offset spectra of dried tapioca starch samples at the outlet of the factory drying process provided a coefficient of determination (R2), standard error of prediction (SEP), bias and residual prediction deviation (RPD) of 0.974, 0.16%, -0.092% and 7.4, respectively. The NIR spectroscopy protocol developed in this study could be a rapid method for evaluation of the moisture content of the tapioca starch in factory laboratories. It indicated the possibility of real-time online monitoring and control of the tapioca starch cake feeder in the drying process. In addition, it was determined that there was a stronger influence of the NIR absorption of both water and starch on the prediction of moisture content of the model.
Comparison and combination of different models for optimal landslide susceptibility zonation
Authors: Chen Guan , Meng Xingmin , Tan Long , Zhang Fanyu , Qiao Liang
Published: October 2014

It is important to compare different methods and apply combined models for landslide susceptibility zonation on a regional scale for land-use planning and hazard mitigation. The purpose of this study is attempt to obtain an optimal landslide susceptibility zonation in a severely landslide affected region where the available data are very limited. Six single models (analytical hierarchy process (AHP), logistic regression (LR), fuzzy logic (FL), weight of evidence integrated logistic regression (WL), artificial neural network (ANN) and support vector machine (SVM)), were applied to obtain the single landslide susceptibility zonations along the middle reaches of the Bailong River from Zhouqu to Wudu, southern Gansu, China, then these single models were compared, after which the three single models that performed better (LR, ANN and SVM) were selected to prepare the combined zonations. Six conditional independent environmental factors were selected as the explanatory variables that contribute to landslide occurrence (elevation, slope, aspect, distance from fault, lithology and settlement density). The mapped landslides in this region were randomly partitioned into two sets: 80% of the landslides were used for the model training and the remaining 20% were used for validation of the models. Receiver operating characteristic and cost curves were plotted as means of evaluating the quality of the susceptibility zonations for the single and combined models. Results show that the single LR, ANN and SVM are models with superior prediction performance and are more suitable for constructing the combined models in this study. Compared with single models, the combined models provided an improved prediction capability and reduced uncertainties.
Structural analysis of extended Australian continental crust: Capel and Faust basins, Lord Howe Rise
Authors: Higgins Karen , Hashimoto Takehiko , Rollet Nadège , Colwell Jim , Hackney Ron , Milligan Peter
Published: October 2014

The Capel and Faust basins (northern Lord Howe Rise) are located in the SW Pacific between Australia, New Zealand and New Caledonia. New seismic, gravity, magnetic and bathymetry data and rock samples have enabled the construction of a three-dimensional geological model providing insights into the crustal architecture and basin stratigraphy. Multiple large depocentres up to 150 km long and 40 km wide, containing over 6 km of sediment, have been identified. These basins probably evolved through two major Early Cretaceous rifting episodes leading to the final break-up of the eastern Gondwanan margin. Pre-break-up plate restorations and potential field data suggest that pre-rift basement is a collage of several discrete terranes, including a Palaeozoic orogen, pre-rift sedimentary basins and rift-precursor igneous rocks. It is likely that a pre-existing NW-trending basement fabric, inherited from the New England Orogen (onshore eastern Australia), had a strong influence on the evolution of basin architecture. This basement fabric was subjected to oblique rifting along an east–west vector in the ?Early Cretaceous to Cenomanian and NE–SW-oriented orthogonal rifting in the ?Cenomanian to Campanian. This has resulted in three structural provinces in the study area: Eastern Flank, Central Belt and Western Flank.
Machine Learning for Social Multiparty Human--Robot Interaction
Authors: Keizer Simon , Ellen Foster Mary , Wang Zhuoran , Lemon Oliver
Published: October 2014

We describe a variety of machine-learning techniques that are being applied to social multiuser human--robot interaction using a robot bartender in our scenario. We first present a data-driven approach to social state recognition based on
supervised learning
. We then describe an approach to social skills execution—that is, action selection for generating socially appropriate robot behavior—which is based on
reinforcement learning
, using a data-driven simulation of multiple users to train execution policies for social skills. Next, we describe how these components for social state recognition and skills execution have been integrated into an end-to-end robot bartender system, and we discuss the results of a user evaluation. Finally, we present an alternative
unsupervised learning
framework that combines social state recognition and social skills execution based on hierarchical Dirichlet processes and an infinite POMDP interaction manager. The models make use of data from both human--human interactions collected in a number of German bars and human--robot interactions recorded in the evaluation of an initial version of the system.
Nonstrict Hierarchical Reinforcement Learning for Interactive Systems and Robots
Authors: Cuayáhuitl Heriberto , Kruijff-Korbayová Ivana , Dethlefs Nina
Published: October 2014

Conversational systems and robots that use reinforcement learning for policy optimization in large domains often face the problem of limited scalability. This problem has been addressed either by using function approximation techniques that estimate the approximate true value function of a policy or by using a hierarchical decomposition of a learning task into subtasks. We present a novel approach for dialogue policy optimization that combines the benefits of both hierarchical control and function approximation and that allows flexible transitions between dialogue subtasks to give human users more control over the dialogue. To this end, each reinforcement learning agent in the hierarchy is extended with a subtask transition function and a dynamic state space to allow flexible switching between subdialogues. In addition, the subtask policies are represented with linear function approximation in order to generalize the decision making to situations unseen in training. Our proposed approach is evaluated in an interactive conversational robot that learns to play quiz games. Experimental results, using simulation and real users, provide evidence that our proposed approach can lead to more flexible (natural) interactions than strict hierarchical control and that it is preferred by human users.
Miriam Plieninger on language learning with Babbel
Authors: Bauer Daniel , Rathje Billy
Published: October 2014

Babbel's Director of Didactics, Miriam Plieninger, weighs in on how mobile apps are rapidly changing the way we approach language learning.
An Audit Tool for Genome Rearrangement Algorithms
Authors: Galvão Gustavo Rodrigues , Dias Zanoni
Published: October 2014

We consider the combinatorial problem of sorting a permutation using a minimum number of rearrangement events, which finds application in the estimation of evolutionary distance between species. Many variants of this problem, which we generically refer to as the rearrangement sorting problem, have been tackled in the literature, and for most of them, the best known algorithms are approximations or heuristics. In this article, we present a tool, called
GRAAu
, to aid in the evaluation of the results produced by these algorithms. To illustrate its application, we use GRAAu to evaluate the results of four approximation algorithms regarding two variants of the rearrangement sorting problem: the problem of sorting by prefix reversals and the problem of sorting by prefix transpositions. As a result, we show that the approximation ratios of three algorithms are tight and conjecture that the approximation ratio of the remaining one is also tight.
Code-Smell Detection as a Bilevel Problem
Authors: Sahin Dilan , Kessentini Marouane , Bechikh Slim , Deb Kalyanmoy
Published: October 2014

Code smells represent design situations that can affect the maintenance and evolution of software. They make the system difficult to evolve. Code smells are detected, in general, using quality metrics that represent some symptoms. However, the selection of suitable quality metrics is challenging due to the absence of consensus in identifying some code smells based on a set of symptoms and also the high calibration effort in determining manually the threshold value for each metric. In this article, we propose treating the generation of code-smell detection rules as a bilevel optimization problem. Bilevel optimization problems represent a class of challenging optimization problems, which contain two levels of optimization tasks. In these problems, only the optimal solutions to the lower-level problem become possible feasible candidates to the upper-level problem. In this sense, the code-smell detection problem can be treated as a bilevel optimization problem, but due to lack of suitable solution techniques, it has been attempted to be solved as a single-level optimization problem in the past. In our adaptation here, the upper-level problem generates a set of detection rules, a combination of quality metrics, which maximizes the coverage of the base of code-smell examples and artificial code smells generated by the lower level. The lower level maximizes the number of generated artificial code smells that cannot be detected by the rules produced by the upper level. The main advantage of our bilevel formulation is that the generation of detection rules is not limited to some code-smell examples identified manually by developers that are difficult to collect, but it allows the prediction of new code-smell behavior that is different from those of the base of examples. The statistical analysis of our experiments over 31 runs on nine open-source systems and one industrial project shows that seven types of code smells were detected with an average of more than 86% in terms of precision and recall. The results confirm the outperformance of our bilevel proposal compared to state-of-art code-smell detection techniques. The evaluation performed by software engineers also confirms the relevance of detected code smells to improve the quality of software systems.
Unifying on-chip and inter-node switching within the Anton 2 network
Authors: Towles Brian , Grossman J. P. , Greskamp Brian , Shaw David E.
Published: October 2014

The design of network architectures has become increasingly complex as the chips connected by inter-node networkshave emerged as distributed systems in their own right, complete with their own on-chip networks. In Anton 2, a massively parallel special-purpose supercomputer for molecular dynamics simulations, we managed this complexity by reusing the on-chip network as a switch for inter-node traffic. This unified network approach introduces several design challenges. Maintaining fairness within the inter-node network is difficult, as each hop becomes a sequence of many on-chip routing decisions. We addressed this problem with an inverse-weighted arbiter that ensures fairness with low implementation costs. Balancing the load of inter-node traffic across the on-chip network is also critical, and we adopted an optimization approach to design an appropriate routing algorithm. Finally, the on-chip routers carry inter-node traffic, so they must implement inter-node virtual channels to avoid deadlock. In order to keep the routers small and fast, we developed a deadlock-free routing algorithm that reduces the number of virtual channels by one-third relative to previous approaches. The resulting Anton 2 network implementation efficiently utilizes its inter-node channels and provides low messaging latency, while occupying a modest amount of silicon area
A reconfigurable fabric for accelerating large-scale datacenter services
Authors: Putnam Andrew , Caulfield Adrian M. , Chung Eric S. , Chiou Derek , Constantinides Kypros , Demme John , Esmaeilzadeh Hadi , Fowers Jeremy , Gopal Gopi Prashanth , Gray Jan , Haselman Michael , Hauck Scott , Heil Stephen , Hormati Amir , Kim Joo-Young , Lanka Sitaram , Larus James , Peterson Eric , Pope Simon , Smith Aaron , Thong Jason , Xiao Phillip Yi , Burger Doug
Published: October 2014

Datacenter workloads demand high computational capabilities, flexibility, power efficiency, and low cost. It is challenging to improve all of these factors simultaneously. To advance datacenter capabilities beyond what commodity server designs can provide, we have designed and built a composable, reconfigurablefabric to accelerate portions of large-scale software services. Each instantiation of the fabric consists of a 6x8 2-D torus of high-end Stratix V FPGAs embedded into a half-rack of 48 machines. One FPGA is placed into each server, accessible through PCIe, and wired directly to other FPGAs with pairs of 10 Gb SAS cables

In this paper, we describe a medium-scale deployment of this fabric on a bed of 1,632 servers, and measure its efficacy in accelerating the Bing web search engine. We describe the requirements and architecture of the system, detail the critical engineering challenges and solutions needed to make the system robust in the presence of failures, and measure the performance, power, and resilience of the system when ranking candidate documents. Under high load, the largescale reconfigurable fabric improves the ranking throughput of each server by a factor of 95% for a fixed latency distribution--- or, while maintaining equivalent throughput, reduces the tail latency by 29%
MemGuard
Authors: Chen Long , Zhang Zhao
Published: October 2014

Memory system reliability is increasingly a concern as memory cell density and capacity continue to grow. The conventional approach is to use redundant memory bits for error detection and correction, with significant storage, cost and power overheads. In this paper, we propose a novel, system-level scheme called MemGuard for memory error detection. With OS-based checkpointing, it is also able to recover program execution from memory errors. The memory error detection of MemGuard is motivated by memory integrity verification using log hashes. It is much stronger than SECDED in error detection, incurs negligible hardware cost and energy overhead and no storage overhead, and is compatible with various memory organizations. It may play the role of ECC memory in consumer-level computers and mobile devices, without the shortcomings of ECC memory. In server computers, it may complement SECDED ECC or Chipkill Correct by providing even stronger error detectio

We have comprehensively investigated and evaluated the feasibility and reliability of MemGuard. We show that using an incremental multiset hash function and a non-cryptographic hash function, the performance and energy overheads of Mem- Guard are negligible. We use the mathematical deduction and synthetic simulation to prove that MemGuard is robust and reliable.
GangES
Authors: Sastry Hari Siva Kumar , Venkatagiri Radha , Adve Sarita V. , Naeimi Helia
Published: October 2014

As technology scales, the hardware reliability challenge affects a broad computing market, rendering traditional redundancy based solutions too expensive. Software anomaly based hardware error detection has emerged as a low cost reliability solution, but suffers from Silent Data Corruptions (SDCs). It is crucial to accurately evaluate SDC rates and identify SDC producing software locations to develop software-centric low-cost hardware resiliency solutions.

A recent tool, called Relyzer, systematically analyzes an entire application's resiliency to single bit soft-errors using a small set of carefully selected error injection sites. Relyzer provides a practical resiliency evaluation mechanism but still requires significant evaluation time, most of which is spent on error simulations.

This paper presents a new technique called GangES (Gang Error Simulator) that aims to reduce error simulation time. GangES observes that a set or gang of error simulations that result in the same intermediate execution state (after their error injections) will produce the same error outcome; therefore, only one simulation of the gang needs to be completed, resulting in significant overall savings in error simulation time. GangES leverages program structure to carefully select when to compare simulations and what state to compare. For our workloads, GangES saves 57% of the total error simulation time with an overhead of just 1.6%

This paper also explores pure program analyses based techniques that could obviate the need for tools such as GangES altogether. The availability of Relyzer+GangES allows us to perform a detailed evaluation of such techniques. We evaluate the accuracy of several previously proposed program metrics. We find that the metrics we considered and their various linear combinations are unable to adequately predict an instruction's vulnerability to SDCs, further motivating the use of Relyzer+GangES style techniques as valuable solutions for the hardware error resiliency evaluation problem
Real-world design and evaluation of compiler-managed GPU redundant multithreading
Authors: Wadden Jack , Lyashevsky Alexander , Gurumurthi Sudhanva , Sridharan Vilas , Skadron Kevin
Published: October 2014

Reliability for general purpose processing on the GPU (GPGPU) is becoming a weak link in the construction of reliable supercomputer systems. Because hardware protection is expensive to develop, requires dedicated on-chip resources, and is not portable across different architectures, the efficiency of software solutions such as redundant multithreading (RMT) must be explored.

This paper presents a real-world design and evaluation of automatic software RMT on GPU hardware. We first describe a compiler pass that automatically converts GPGPU kernels into redundantly threaded versions. We then perform detailed power and performance evaluations of three RMT algorithms, each of which provides fault coverage to a set of structures in the GPU. Using real hardware, we show that compilermanaged software RMT has highly variable costs. We further analyze the individual costs of redundant work scheduling, redundant computation, and inter-thread communication, showing that no single component in general is responsible for high overheads across all applications; instead, certain workload properties tend to cause RMT to perform well or poorly. Finally, we demonstrate the benefit of architectural support for RMT with a specific example of fast, register-level thread communication
ArchRanker
Authors: Chen Tianshi , Guo Qi , Tang Ke , Temam Olivier , Xu Zhiwei , Zhou Zhi-Hua , Chen Yunji
Published: October 2014

Architectural Design Space Exploration (DSE) is a notoriously difficult problem due to the exponentially large size of the design space and long simulation times. Previously, many studies proposed to formulate DSE as a regression problem which predicts architecture responses (e.g., time, power) of a given architectural configuration. Several of these techniques achieve high accuracy, though often at the cost of significant simulation time for training the regression models.

We argue that the information the architect mostly needs during the DSE process is whether a given configuration will perform better than another one in the presences of design constraints, or better than any other one seen so far, rather than precisely estimating the performance of that configuration.

Based on this observation, we propose a novel rankingbased approach to DSE where we train a model to predict which of two architecture configurations will perform best. We show that, not only this ranking model more accurately predicts the relative merit of two architecture configurations than an ANN-based state-of-the-art regression model, but also that it requires much fewer training simulations to achieve the same accuracy, or that it can be used for and is even better at quantifying the performance gap between two configurations

We implement the framework for training and using this model, called ArchRanker, and we evaluate it on several DSE scenarios (unicore/multicore design spaces, and both time and power performance metrics). We try to emulate as closely as possible the DSE process by creating constraint-based scenarios, or an iterative DSE process. We find that ArchRanker makes 29:68% to 54:43% fewer incorrect predictions on pairwise relative merit of configurations (tested with 79,800 configuration pairs) than an ANN-based regression model across all DSE scenarios considered (values averaged over all benchmarks for each scenario). We also find that, to achieve the same accuracy as ArchRanker, the ANN often requires three times more training simulations
Aladdin
Authors: Shao Yakun Sophia , Reagen Brandon , Wei Gu-Yeon , Brooks David
Published: October 2014

Hardware specialization, in the form of accelerators that provide custom datapath and control for specific algorithms and applications, promises impressive performance and energy advantages compared to traditional architectures. Current research in accelerator analysis relies on RTL-based synthesis flows to produce accurate timing, power, and area estimates. Such techniques not only require significant effort and expertise but are also slow and tedious to use, making large design space exploration infeasible. To overcome this problem, we present Aladdin, a pre-RTL, power-performance accelerator modeling framework and demonstrate its application to system-on-chip (SoC) simulation. Aladdin estimates performance, power, and area of accelerators within 0.9%, 4.9%, and 6.6% with respect to RTL implementations. Integrated with architecture-level core and memory hierarchy simulators, Aladdin provides researchers an approach to model the power and performance of accelerators in an SoC environment
SynFull
Authors: Badr Mario , Jerger Natalie Enright
Published: October 2014

Modern and future many-core systems represent complex architectures. The communication fabrics of these large systems heavily influence their performance and power consumption. Current simulation methodologies for evaluating networks-on-chip (NoCs) are not keeping pace with the increased complexity of our systems; architects often want to explore many different design knobs quickly. Methodologies that capture workload trends with faster simulation times are highly beneficial at early stages of architectural exploration. We propose SynFull, a synthetic traffic generation methodology that captures both application and cache coherence behaviour to rapidly evaluate NoCs. SynFull allows designers to quickly indulge in detailed performance simulations without the cost of long-running full-system simulation. By capturing a full range of application and coherence behaviour, architects can avoid the over or underdesign of the network as may occur when using traditional synthetic traffic patterns such as uniform random. SynFull has errors as low as 0.3% and provides 50x speedup on average over full-system simulation