bluuebunny/crossref_metadata_2025 huggingface dataset:
Pelvic organ prolapse transvaginal repair by the Prolift system: Evaluation of efficacy and complications after a 4.5 years follow up
Authors: Benbouzid Sabrina , Cornu Jean‐Nicolas , Benchikh Amine , Chanu Tiffany , Haab François , Delmas Vincent
Published: July 2012

Objectives:  The Prolift system is a polypropylene device designed for pelvic organ prolapse repair by a transvaginal approach. Numerous studies have reported on short‐term outcomes of this procedure, but long‐term studies are lacking.

Methods:  A retrospective study of patients who underwent pelvic organ prolapse repair by Prolift between September 2005 and September 2008 was carried out in two tertiary reference centers by two experienced surgeons. Preoperative and postoperative follow up was based on medical records of baseline and follow‐up visits with complete clinical examination, including Pelvic Organ Prolapse Quantification stage. At last follow up, the Pelvic Floor Distress Inventory‐20 questionnaire was assessed by telephone interview. Cure was defined as an anatomical success at last follow up, being a Pelvic Organ Prolapse Quantification stage ≤1 without further surgical intervention in any compartment.

Results:  A total of 75 patients were included in this analysis with a mean follow up of 53.7 ± 8.8 months (range 36–72 months). Patients were treated with two‐arm Prolift posterior, four‐arm Prolift anterior and six‐arm Prolift total in three (4%), 51 (69%) and 21 (27%) cases, respectively. At last follow up, 64 (85.3%) patients were cured, with no prolapse recurrence. Mesh exposure occurred in four (5.3%) patients. The Pelvic Floor Distress Inventory‐20 symptom score was low at last follow up (median 8, range 3–18), in accordance with objective cure data.

Conclusions:  The Prolift system is safe and efficacious for pelvic organ prolapse repair by transvaginal approach after a 4.5‐year follow up.
How do we manage venous thromboembolism in pregnancy? A retrospective review of the practice of diagnosing and managing pregnancy‐related venous thromboembolism at two major hospitals in Australia and New Zealand
Authors: Chan N. , Merriman E. , Hyder S. , Woulfe T. , Tran H. , Chunilal S.
Published: July 2012

Background

North American and European literature suggest that the incidence rate for pregnancy‐related thromboembolism (VTE) ranges from 0.5 to 2 per 1000 pregnancies. However, there is a paucity of data regarding pregnancy‐related VTE in Australia and New Zealand.

Aims

To define the epidemiology, management and adverse effects of pregnancy‐related VTE in Australia and New Zealand.

Method

Retrospective chart review of pregnant patients with objectively diagnosed pregnancy‐related VTE at Monash Medical Centre and the North Shore Hospital from January 2007 to March 2011.

Results

Sixty women with VTE were identified, 31 and 29 in the antepartum and post‐partum period respectively. VTE occurred as early as 8 weeks of gestation. There was a trend towards higher proportion of PE in the postpartum period. Most antenatal patients were started on enoxaparin and dosed according to weight at diagnosis. A wide variability in maintenance dosing strategies was observed. Three (5%, 95% CI: 1% to 14%) patients suffered major bleeds, all occurring post‐partum. Recurrences occurred in two post‐partum patients who received a truncated course of enoxaparin for distal deep‐vein thrombosis. Although more women had an induction of labour, this did not translate into an increased Caesarean section rate.

Conclusion

The epidemiology of pregnancy‐related VTE is similar to that of other developed countries. All three bleeding events occurred in the immediate post‐partum setting, highlighting the need for caution at this critical time. VTE recurrences occurred in those women with post‐partum distal deep‐vein thrombosis treated with an abbreviated course of enoxaparin.
Do we need cardiac arrest centres in Australia?
Authors: Stub D. , Bernard S. , Smith K. , Bray J. E. , Cameron P. , Duffy S. J. , Kaye D. M.
Published: July 2012

The mortality rate post admission to hospital after successful resuscitation from out‐of‐hospital cardiac arrest is high, with significant variation between regions and individual institutions. While prehospital factors such as age, bystander cardiopulmonary resuscitation and total cardiac arrest time are known to influence outcome, several aspects of post‐resuscitative care including therapeutic hypothermia, coronary intervention and goal‐directed therapy may also influence patient survival. Regional systems of care have improved provider experience and patient outcomes for those with ST elevation myocardial infarction and life‐threatening traumatic injury. In particular, hospital factors such as hospital size and interventional cardiac care capabilities have been found to influence patient mortality. This paper reviews the evidence supporting the possible development and implementation of Australian cardiac arrest centres.
Relapsed multiple myeloma: who benefits from salvage autografts?
Authors: Chow A. W. S. , Lee C. H. S. , Hiwase D. K. , To L. B. , Horvath N.
Published: July 2012

Background

Multiple myeloma is incurable despite the advance of autologous stem cell transplant (ASCT) and novel agents (thalidomide, bortezomib, lenalidomide). The role of ASCT as salvage therapy in relapsed myeloma remains unclear.

Aim

To identify and refine the predictors of survival following salvage ASCT for relapsed multiple myeloma, so that they can be applied clinically for patient selection.

Methods

Retrospective review of patients treated salvage ASCT for relapsed myeloma at our centre from 1992 to 2011.

Results

Following an initial ASCT at diagnosis, 30 patients underwent salvage ASCT for subsequent relapse, with the median time to first relapse/progression being 30.2 months. All patients received reinduction, then melphalan‐based conditioning with salvage ASCT. Non‐relapse mortality at 100 days following salvage ASCT was 3%. The median overall survival and progression‐free survival following salvage ASCT were 45 and 22 months respectively. The progression‐free interval (PFI) after initial ASCT predicted survival outcomes in a time‐dependent manner. With PFI following initial ASCT of <18, 18–36 and ≥36 months, the median progression‐free survival following salvage ASCT was 4.2, 13.8 and 49.1 months respectively (P < 0.0001). The median overall survival was 10.7, 30.9 and 86.1 months respectively (P < 0.0001).

Conclusions

Salvage ASCT is an effective and safe treatment option in selected patients and should be considered in patients relapsing ≥36 months after their initial ASCT. The time‐dependent relationship between PFI and salvage ASCT outcome is important when stratifying patient groups who may benefit from this procedure.
High‐dose cytarabine (24 g/m2) in combination with idarubicin (HiDAC‐3) results in high first‐cycle response with limited gastrointestinal toxicity in adult acute myeloid leukaemia
Authors: Low M. , Lee D. , Coutsouvelis J. , Patil S. , Opat S. , Walker P. , Schwarer A. , Salem H. , Avery S. , Spencer A. , Wei A.
Published: July 2012

Background/Aim

Although induction chemotherapy comprising high‐dose cytarabine (HiDAC) in combination with idarubicin and etoposide or ‘ICE’ for adult acute myeloid leukaemia (AML) produces a complete remission rate of nearly 80%, gastrointestinal toxicity is significant. Omission of etoposide may produce similar clinical outcomes with potentially less gastrointestinal toxicity.

Methods

Fifty‐three consecutive patients aged 15–60 with newly diagnosed AML, receiving high‐dose cytarabine induction at the Alfred Hospital, Melbourne, were retrospectively analysed. Regimens included HiDAC‐3 (idarubicin 12 mg/m2 day 1–3, cytarabine 3 gm/m2 bd day 1,3,5,7) or ICE (idarubicin 9 mg/m2 day 1–3, cytarabine 3 g/m2 bd day 1,3,5,7, etoposide 75 mg/m2 day 1–7). Toxicity was assessed using Common Terminology Criteria for Adverse Events version 4.03.

Results

Thirty‐one patients received HIDAC‐3 and 22 patients received ICE induction. HiDAC‐3 was better tolerated than ICE in terms of lower frequency of grade 3–4 nausea (0% vs 41%; P < 0.01), grade 3–4 diarrhoea (26% vs 55%; P = 0.05), lower rates of radiologically evident enterocolitis (6% vs 32%; P = 0.03) and less cumulative days of total parenteral nutrition use (1.2 vs 7.3 days; P < 0.01). Times to haematological recovery were similar between the two regimens. Thirty‐day mortality was 0% for HiDAC‐3 and 9% for ICE. Eighty‐four per cent of HiDAC‐3‐treated patients achieved complete remission after the first cycle of therapy, compared with 77% with ICE. No differences in survival were evident between the two regimens.

Conclusions

HiDAC‐3 is a clinically effective induction regimen for adult AML, producing a high rate of first‐cycle complete remission with less treatment‐related gastrointestinal toxicity than ICE.
Primary motor and premotor cortex in implicit sequence learning – evidence for competition between implicit and explicit human motor memory systems
Authors: Kantak Shailesh S. , Mummidisetty Chaithanya K. , Stinear James W.
Published: July 2012

Implicit and explicit memory systems for motor skills compete with each other during and after motor practice. Primary motor cortex (M1) is known to be engaged during implicit motor learning, while dorsal premotor cortex (PMd) is critical for explicit learning. To elucidate the neural substrates underlying the interaction between implicit and explicit memory systems, adults underwent a randomized crossover experiment of anodal transcranial direct current stimulation (AtDCS) applied over M1, PMd or sham stimulation during implicit motor sequence (serial reaction time task, SRTT) practice. We hypothesized that M1‐AtDCS during practice will enhance online performance and offline learning of the implicit motor sequence. In contrast, we also hypothesized that PMd‐AtDCS will attenuate performance and retention of the implicit motor sequence. Implicit sequence performance was assessed at baseline, at the end of acquisition (EoA), and 24 h after practice (retention test, RET). M1‐AtDCS during practice significantly improved practice performance and supported offline stabilization compared with Sham tDCS. Performance change from EoA to RET revealed that PMd‐AtDCS during practice attenuated offline stabilization compared with M1‐AtDCS and sham stimulation. The results support the role of M1 in implementing online performance gains and offline stabilization for implicit motor sequence learning. In contrast, enhancing the activity within explicit motor memory network nodes such as the PMd during practice may be detrimental to offline stabilization of the learned implicit motor sequence. These results support the notion of competition between implicit and explicit motor memory systems and identify underlying neural substrates that are engaged in this competition.
High serum androstenedione levels correlate with impaired memory in the surgically menopausal rat: a replication and new findings
Authors: Camp Bryan W. , Gerson Julia E. , Tsang Candy Wing S. , Villa Stephanie R. , Acosta Jazmin I. , Blair Braden B. , Hoffman Ann N. , Conrad Cheryl D. , Bimonte‐Nelson Heather A.
Published: July 2012

After natural menopause in women, androstenedione becomes the primary hormone secreted by the residual follicle‐depleted ovaries. In two independent studies, in rodents that had undergone ovarian follicular depletion, we found that higher endogenous serum androstenedione levels correlated with increased working memory errors. This led to the hypothesis that higher androstenedione levels impair memory. The current study directly tested this hypothesis, examining the cognitive effects of exogenous androstenedione administration in rodents. Middle‐aged ovariectomised rats received vehicle or one of two doses of androstenedione. Rats were tested on a spatial working and reference memory maze battery including the water‐radial arm maze, Morris water maze (MM) and delay match‐to‐sample task. Androstenedione at the highest dose impaired reference memory as well as the ability to maintain performance as memory demand was elevated. This was true for both high temporal demand memory retention of one item of spatial information, as well as the ability to handle multiple items of spatial working memory information. We measured glutamic acid decarboxylase (GAD) protein in multiple brain regions to determine whether the gamma‐aminobutyric acid (GABA) system relates to androstenedione‐induced memory impairments. Results showed that higher entorhinal cortex GAD levels were correlated with worse MM performance, irrespective of androstenedione treatment. These findings suggest that androstenedione, the main hormone produced by the follicle‐depleted ovary, is detrimental to working memory, reference memory and memory retention. Furthermore, while spatial reference memory performance might be related to the GABAergic system, it does not appear to be altered with androstenedione administration, at least at the doses used in the current study.
Sex‐dependent differences in behavior and hippocampal neurogenesis after irradiation to the young mouse brain
Authors: Roughton Karolina , Kalm Marie , Blomgren Klas
Published: July 2012

Cranial radiotherapy in the treatment of pediatric malignancies may lead to cognitive deficits, and girls suffer more severe deficits than boys. However, most experimental studies are performed on male animals only. Our aim was to investigate possible long‐term gender differences in response to cranial irradiation (IR). Basal neurogenesis in non‐irradiated mice was higher in females but this was not apparent until the animals were adult. Male and female C57BL/6J mice received a single dose of 8 Gy to the whole brain on postnatal day 14 and were killed 6 h or 4 months later. Proliferation in the subgranular zone of the dentate gyrus in the hippocampus, as judged by the number of phosphohistone H3‐positive cells, was reduced by half 6 h after IR in both males and females. The reduced proliferation was still obvious 4 months after IR. Consequently, the continuous addition of new neurons to the granule cell layer (GCL) during brain growth was reduced in irradiated mice, and the reduction was more pronounced in females. This resulted in hampered growth of the GCL, reduced bromodeoxyuridine incorporation in adulthood, and severely reduced adult neurogenesis, as judged by the number of doublecortin‐positive cells in the GCL. In an open‐field test, locomotor activity was increased in both males and females after IR and anxiety levels were increased, more so in females. In an IntelliCage test, place learning was impaired by IR in females but not males.
Long‐lasting small‐amplitude TRP‐mediated dendritic depolarizations in CA1 pyramidal neurons are intrinsically stable and originate from distal tuft regions
Authors: Petersson Marcus E. , Fransén Erik
Published: July 2012

In several regions of the nervous system, neurons display bi‐ or multistable intrinsic properties. Such stable states may be subthreshold and long‐lasting, and can appear as a sustained afterdepolarization. In hippocampal CA1 pyramidal neurons, small‐amplitude (1 mV) long‐lasting (seconds) afterdepolarizations have been reported and are thought to depend on calcium‐activated nonselective (CAN) currents recently identified as transient receptor potential (TRP) channels. Continuing our previous experimental and computational work on synaptically metabotropic glutamate receptor (mGluR)‐activated TRP currents, we here explore small‐amplitude long‐lasting depolarizations in a detailed multicompartmental model of a CA1 pyramidal neuron. We confirm a previous hypothesis suggesting that the depolarization results from an interplay of TRP and voltage‐gated calcium channels, and contribute to the understanding of the depolarization in several ways. Specifically, we show that: (i) the long‐lasting depolarization may be intrinsically stable to weak excitatory and inhibitory input, (ii) the phenomenon is essentially located in distal apical dendrites, (iii) induction is facilitated if simultaneous input arrives at several dendritic branches, and if calcium‐ and/or mGluR‐evoked signals undergo summation, suggesting that both spatial and temporal synaptic summation might be required for the depolarization to occur and (iv) we also show that the integration of inputs to oblique dendrites is strongly modulated by the presence of small‐amplitude long‐lasting depolarizations in distal tuft dendrites. To conclude, we suggest that small‐amplitude long‐lasting dendritic depolarizations may contribute to sustaining neural information during behavioural tasks in cases where information is separated in time, as in trace conditioning and delay tasks.
Pattern‐motion selective responses in MT, MST and the pulvinar of humans
Authors: Villeneuve M. Y. , Thompson B. , Hess R. F. , Casanova C.
Published: July 2012

Plaid stimuli are often used to investigate the mechanisms involved in the integration and segregation of motion information. Considering the perceptual importance of such mechanisms, only a very limited number of visual brain areas have been found to be specifically involved in motion integration. These are the human (h)MT+ complex, area V3 and the pulvinar. The hMT+ complex can be functionally subdivided into two separate areas, middle temporal area (MT) and medial superior temporal area (MST); however, it is currently unclear whether these distinct sub‐regions have different responses to plaid stimuli. To address this issue we used functional magnetic resonance imaging to quantify the relative response of MT and MST to component and pattern motion. Participants viewed plaid stimuli that were constrained to result in the perception of either component motion (segregation of motion information) or pattern motion (integration of motion information). MT/MST segregation was achieved using a moving dot stimulus that allowed stimulation of each visual hemifield either in unison or separately. We found pattern motion selective responses in both MT and MST. Consistent with previous reports, activity indicative of pattern motion selectivity was also found in the pulvinar as well as in other extrastriate areas. These results demonstrate that MT, MST and the pulvinar are involved in the complex motion integration mechanisms that are triggered by plaid stimuli. This reinforces the concept that integrative computations take place in a distributed neuronal circuit both in cortical and sub‐cortical networks.
Incidence and predictors of difficult laryngoscopy in 11.219 pediatric anesthesia procedures
Authors: Heinrich Sebastian , Birkholz Torsten , Ihmsen Harald , Irouschek Andrea , Ackermann Andreas , Schmidt Joachim
Published: July 2012

Objective:  Difficult laryngoscopy in pediatric patients undergoing anesthesia.

Aim:  This retrospective analysis was conducted to investigate incidence and predictors of difficult laryngoscopy in a large cohort of pediatric patients receiving general anesthesia with endotracheal intubation.

Background:  Young age and craniofacial dysmorphy are predictors for the difficult pediatric airway and difficult laryngoscopy. For difficult laryngoscopy, other general predictors are not yet described.

Methods:  Retrospectively, from a 5‐year period, data from 11.219 general anesthesia procedures in pediatric patients with endotracheal intubation using age‐adapted Macintosh blades in a single center (university hospital) were analyzed statistically.

Results:  The overall incidence of difficult laryngoscopy [Cormack and Lehane (CML) grade III and IV] was 1.35%. In patients younger than 1 year, the incidence of CML III or IV was significantly higher than in the older patients (4.7% vs 0.7%). ASA Physical Status III and IV, a higher Mallampati Score (III and IV) and a low BMI were all associated (P < 0.05) with difficult laryngoscopy. Patients undergoing oromaxillofacial surgery and cardiac surgery showed a significantly higher rate of CML III/IV findings.

Conclusion:  The general incidence of difficult laryngoscopy in pediatric anesthesia is lower than in adults. Our results show that the risk of difficult laryngoscopy is much higher in patients below 1 year of age, in underweight patients and in ASA III and IV patients. The underlying disease might also contribute to the risk. If the Mallampati score could be obtained, prediction of difficult laryngoscopy seems to be reliable. Our data support the existing recommendations for a specialized anesthesiological team to provide safe anesthesia for infants and neonates.
Tracheal extubation of deeply anesthetized pediatric patients: a comparison of sevoflurane and sevoflurane in combination with low‐dose remifentanil
Authors: Shen Xia , Hu Chunbo , Li Wenxian
Published: July 2012

Purpose:  We aimed to observe the emergence characteristics of children tracheally extubated in deep anesthesia with sevoflurane or sevoflurane in combination with low‐dose remifentanil.

Methods:  We randomly allocated 50 pediatric patients undergoing elective electronic cochlear implantation to groups either receiving sevoflurane (Group S, n = 25), or sevoflurane plus low‐dose remifentanil (Group SR, n = 25), during extubation from anesthesia. In Group S, subjects were tracheally extubated while breathing 1.3 times the minimal effective concentration of sevoflurane. In Group SR, subjects were tracheally extubated while breathing 1.0 times the minimal effective concentration of sevoflurane with 0.02–0.05 μg·kg−1 per min remifentanil. Recovery characteristics and airway complications were noted.

Results:  There was no significant difference in age, weight, sex, and duration of anesthesia. The average remifentanil rate was 0.036 μg·kg−1 per min, and compared with Group S, patients in Group SR had a lower respiratory rate (17.3 vs 20.2 per minute, P < 0.05) and a higher ETCO2 (52.3 vs 49.4 mmHg, P < 0.05). Oral airway usage was also less frequent in Group SR (44% vs 16%, P < 0.01). Additionally, the time from extubation to spontaneous eye opening was shorter in Group SR (10.9 min vs 19.6 min, P < 0.01). Finally, six patients in Group S and five patients in Group SR had a pediatric anesthesia emergence delirium score >10.

Conclusions:  Low‐dose remifentanil in combination with sevoflurane provided rapid recovery and was safe for deep tracheal extubation in deep anesthesia in pediatric patients.
MEGA‐EVENTS AND SECTORAL EMPLOYMENT: THE CASE OF THE 1996 OLYMPIC GAMES
Authors: FEDDERSEN ARNE , MAENNIG WOLFGANG
Published: July 2012

Using the data of the 1996 Olympic Games, this paper analyzes the economic impact of a mega‐sporting event. Earlier studies are extended in several ways. First, monthly rather than quarterly data are employed. Second, the impact is analyzed for 16 different sectors. Third, we use a nonparametric approach to flexibly isolate employment effects. Hardly any evidence for a persistent shift in the aftermath of or the preparation for the Olympic Games is supported. We find significant positive employment effects exclusively during the Olympic Games. These short‐term effects are concentrated in the sectors of “retail trade,”“accommodation and food services,” and “arts, entertainment, and recreation.” (JEL H54, R12, L83)
Commercializing Nature: Mangrove Conservation and Female Oyster Collectors in The Gambia
Authors: Crow Britt , Carney Judith
Published: July 2012

Abstract:  Taking a political ecology approach, this paper offers a critical evaluation of conservation efforts undertaken in Gambia's Tanbi Wetland National Park (TWNP), a “wetland of international importance” as designated by the Ramsar Convention. Focusing on the oyster commercialization component of the World Wildlife Fund's Gambia–Senegal Sustainable Fisheries Program (GSFP) in the TWNP mangrove forests, we identify oystering practices that promote mangrove conservation and others that conflict with sustainable management. The project, which aims to commercialize oyster culture through local women, is entirely production oriented, ignoring the ways in which oysters are prepared for market. As a result, degradation of the very mangrove forests the GSFP aims to conserve may be accelerated. The project selectively engages with local environmental knowledge and fails to consider the implications of expanding the value chains for oysters and their shells. Unless the World Wildlife Fund addresses these issues, its conservation objectives and potential socioeconomic benefits may be compromised.
A TWO‐STAGE WIN–WIN MULTIATTRIBUTE NEGOTIATION MODEL: OPTIMIZATION AND THEN CONCESSION
Authors: Pan Li , Luo Xudong , Meng Xiangxu , Miao Chunyan , He Minghua , Guo Xingchen
Published: July 2012

Many automated negotiation models have been developed to solve the conflict in many distributed computational systems. However, the problem of finding win–win outcome in multiattribute negotiation has not been tackled well. To address this issue, based on an evolutionary method of multiobjective optimization, this paper presents a negotiation model that can find win–win solutions of multiple attributes, but needs not to reveal negotiating agents’ private utility functions to their opponents or a third‐party mediator. Moreover, we also equip our agents with a general type of utility functions of interdependent multiattributes, which captures human intuitions well. In addition, we also develop a novel time‐dependent concession strategy model, which can help both sides find a final agreement among a set of win–win ones. Finally, lots of experiments confirm that our negotiation model outperforms the existing models developed recently. And the experiments also show our model is stable and efficient in finding fair win–win outcomes, which is seldom solved in the existing models.
EMOTAG: AN APPROACH TO AUTOMATED MARKUP OF EMOTIONS IN TEXTS
Authors: Francisco Virginia , Gervás Pablo
Published: July 2012

This paper presents an approach to the automated markup of texts with emotional labels. The approach considers two possible representations of emotions in parallel: emotional categories (emotional tags used to refer to emotions) and emotional dimensions (measures that try to model the essential aspects of emotions numerically). For each representation, a corpus of example texts previously annotated by human evaluators is mined for an initial assignment of emotional features to words. This results in a list of emotional words (LEW) which becomes a useful resource for later automated markup. The algorithm proposed for the automated markup of text closely mirrors the steps taken during feature extraction, employing a combination of the LEW resource and the ANEW word list for the actual assignment of emotional features, and WordNet for knowledge‐based expansion of words not occurring in either and an ontology of emotional categories. The algorithm for automated markup is tested and the results are discussed with respect to three main issues: the relative adequacy of each of the representations used, correctness and coverage of the proposed algorithm, and additional techniques and solutions that may be employed to improve the results. The average percentage of success obtained by our approach when it marks up with emotional dimensions is around 80% and when it marks up with emotional categories is around 50%. The main contribution of the approach presented in this paper is that it allows dimensions and categories at different levels of abstraction to operate simultaneously during markup.
QUADRATIC TSALLIS ENTROPY BIAS AND GENERALIZED MAXIMUM ENTROPY MODELS
Authors: Hou Yuexian , Wang Bo , Song Dawei , Cao Xiaochun , Li Wenjie
Published: July 2012

In density estimation task, Maximum Entropy (Maxent) model can effectively use reliable prior information via nonparametric constraints, that is, linear constraints without empirical parameters. However, reliable prior information is often insufficient, and parametric constraints becomes necessary but poses considerable implementation complexity. Improper setting of parametric constraints can result in overfitting or underfitting. To alleviate this problem, a generalization of Maxent, under Tsallis entropy framework, is proposed. The proposed method introduces a convex quadratic constraint for the correction of (expected) quadratic Tsallis Entropy Bias (TEB). Specifically, we demonstrate that the expected quadratic Tsallis entropy of sampling distributions is smaller than that of the underlying real distribution with regard to frequentist, Bayesian prior, and Bayesian posterior framework, respectively. This expected entropy reduction is exactly the (expected) TEB, which can be expressed by the closed‐form formula and acts as a consistent and unbiased correction with an appropriate convergence rate. TEB indicates that the entropy of a specific sampling distribution should be increased accordingly. This entails a quantitative reinterpretation of the Maxent principle. By compensating TEB and meanwhile forcing the resulting distribution to be close to the sampling distribution, our generalized quadratic Tsallis Entropy Bias Compensation (TEBC) Maxent can be expected to alleviate the overfitting and underfitting. We also present a connection between TEB and Lidstone estimator. As a result, TEB–Lidstone estimator is developed by analytically identifying the rate of probability correction in Lidstone. Extensive empirical evaluation shows promising performance of both TEBC Maxent and TEB‐Lidstone in comparison with various state‐of‐the‐art density estimation methods.
ACTION FAILURE RECOVERY VIA MODEL‐BASED DIAGNOSIS AND CONFORMANT PLANNING
Authors: Micalizio Roberto
Published: July 2012

A plan carried on in the real world may be affected by a number of unexpected events, plan threats, which cause significant deviations between the intended behavior of the plan executor (i.e., the agent) and the observed one. These deviations are typically considered as action failures. This paper addresses the problem of recovering from action failures caused by a specific class of plan threats: faults in the functionalities of the agent. The problem is approached by exploiting techniques of the Model‐Based Diagnosis (MBD) for detecting failures (plan execution monitoring) and for explaining these failures in terms of faulty functionalities (agent diagnosis). The recovery process is modeled as a replanning problem aimed at fixing the faulty components identified by the agent diagnosis. However, since the diagnosis is in general ambiguous (a failure may be explained by alternative faults), the recovery has to deal with such an uncertainty. The paper advocates the adoption of a conformant planner, which guarantees that the recovery plan, if it exists, is executable no matter what the actual cause of the failure. The paper focuses on a single agent performing its own plan, however the proposed methodology takes also into account that agents are typically situated into a multiagent scenario and that commitments between agents may exist. The repair strategy is therefore conceived to overcome the causes of a failure while assuring the commitments an agent has agreed with other team members.
GOAL‐DRIVEN AUTONOMY FOR RESPONDING TO UNEXPECTED EVENTS IN STRATEGY SIMULATIONS
Authors: Klenk Matthew , Molineaux Matt , Aha David W.
Published: July 2012

To operate autonomously in complex environments, an agent must monitor its environment and determine how to respond to new situations. To be considered intelligent, an agent should select actions in pursuit of its goals, and adapt accordingly when its goals need revision. However, most agents assume that their goals are given to them; they cannot recognize when their goals should change. Thus, they have difficulty coping with the complex environments of strategy simulations that are continuous, partially observable, dynamic, and open with respect to new objects. To increase intelligent agent autonomy, we are investigating a conceptual model for goal reasoning called Goal‐Driven Autonomy (GDA), which allows agents to generate and reason about their goals in response to environment changes. Our hypothesis is that GDA enables an agent to respond more effectively to unexpected events in complex environments. We instantiate the GDA model in ARTUE (Autonomous Response to Unexpected Events), a domain‐independent autonomous agent. We evaluate ARTUE on scenarios from two complex strategy simulations, and report on its comparative benefits and limitations. By employing goal reasoning, ARTUE outperforms an off‐line planner and a discrepancy‐based replanner on scenarios requiring reasoning about unobserved objects and facts and on scenarios presenting opportunities outside the scope of its current mission.
DECENTRALIZED SUPPLY CHAIN FORMATION USING MAX‐SUM LOOPY BELIEF PROPAGATION
Authors: Winsper Michael , Chli Maria
Published: July 2012

Supply chain formation is the process by which a set of producers within a network determine the subset of these producers able to form a chain to supply goods to one or more consumers at the lowest cost. This problem has been tackled in a number of ways, including auctions, negotiations, and argumentation‐based approaches. In this paper we show how this problem can be cast as an optimization of a pairwise cost function. Optimizing this class of energy functions is NP‐hard but efficient approximations to the global minimum can be obtained using loopy belief propagation (LBP). Here we detail a max‐sum LBP‐based approach to the supply chain formation problem, involving decentralized message‐passing between supply chain participants. Our approach is evaluated against a well‐known decentralized double‐auction method and an optimal centralized technique, showing several improvements on the auction method: it obtains better solutions for most network instances which allow for competitive equilibrium (Competitive equilibrium in Walsh and Wellman is a set of producer costs which permits a Pareto optimal state in which agents in the allocation receive non‐negative surplus and agents not in the allocation would acquire non‐positive surplus by participating in the supply chain) while also optimally solving problems where no competitive equilibrium exists, for which the double‐auction method frequently produces inefficient solutions.
DECLARATIVE SPECIFICATION OF FAULT TOLERANT AUCTION PROTOCOLS: THE ENGLISH AUCTION CASE STUDY
Authors: Dragoni Nicola , Gaspari Mauro
Published: July 2012

Auction mechanisms are nowadays widely used in electronic commerce Web sites for buying and selling items among different users. The increasing importance of auction protocols in the negotiation phase is not limited to online marketplaces. In fact, the wide applicability of auctions as resource‐allocation and negotiation mechanisms have also led to a great deal of interest in auctions within the agent community. A challenging issue for agents operating in open Multiagent Systems (such as the emerging semantic Web infrastructure) concerns the specification of declarative communication rules which could be published and shared allowing agents to dynamically engage well‐known and trusted negotiation protocols. To cope with real‐world applications, these rules should also specify fault tolerant patterns of interaction, enabling negotiating agents to interact with each other tolerating failures, for instance terminating an auction process even if some bidding agents dynamically crash. In this paper, we propose an approach to specify fault tolerant auction protocols in open and dynamic environments by means of communication rules dealing with crash failures of agents. We illustrate these concepts considering a case study about the specification of an English Auction protocol which tolerate crashes of bidding agents and we discuss its properties.
Per‐Vertex Defocus Blur for Stochastic Rasterization
Authors: Munkberg Jacob , Toth Robert , Akenine‐Möller Tomas
Published: July 2012

We present user‐controllable and plausible defocus blur for a stochastic rasterizer. We modify circle of confusion coefficients per vertex to express more general defocus blur, and show how the method can be applied to limit the foreground blur, extend the in‐focus range, simulate tilt‐shift photography, and specify per‐object defocus blur. Furthermore, with two simplifying assumptions, we show that existing triangle coverage tests and tile culling tests can be used with very modest modifications. Our solution is temporally stable and handles simultaneous motion blur and depth of field.
Pre‐convolved Radiance Caching
Authors: Scherzer Daniel , Nguyen Chuong H. , Ritschel Tobias , Seidel Hans‐Peter
Published: July 2012

The incident indirect light over a range of image pixels is often coherent. Two common approaches to exploit this inter‐pixel coherence to improve rendering performance are Irradiance Caching and Radiance Caching. Both compute incident indirect light only for a small subset of pixels (the cache), and later interpolate between pixels. Irradiance Caching uses scalar values that can be interpolated efficiently, but cannot account for shading variations caused by normal and reflectance variation between cache items. Radiance Caching maintains directional information, e.g., to allow highlights between cache items, but at the cost of storing and evaluating a Spherical Harmonics (SH) function per pixel. The arithmetic and bandwidth cost for this evaluation is linear in the number of coefficients and can be substantial. In this paper, we propose a method to replace it by an efficient per‐cache item pre‐filtering based on MIP maps — such as previously done for environment maps — leading to a single constant‐time lookup per pixel. Additionally, per‐cache item geometry statistics stored in distance‐MIP maps are used to improve the quality of each pixel's lookup. Our approximate interactive global illumination approach is an order of magnitude faster than Radiance Caching with Phong BRDFs and can be combined with Monte Carlo‐raytracing, Point‐based Global Illumination or Instant Radiosity.
Quantized Point‐Based Global Illumination
Authors: Buchholz Bert , Boubekeur Tamy
Published: July 2012

Point‐based global illumination (PBGI) uses a dense point sampling of the scene's surfaces to approximate indirect light transport and is intensively used in 3D motion pictures and special effects. Each point caches the reflected light using a spherical function and is typically used in a subsequent rasterization process to compute color bleeding and ambient occlusion in an economic, noise‐free fashion. The entire point set is organized in a spatial tree structure which models the light transport hierarchically, enabling fast adaptive shading on receivers (e.g., unprojected pixels). One of the major limitations of PBGI is related to the size of this tree, which can quickly become too large to fit in memory for complex scenes. However, we observe that, just as with natural images, this point data set is extremely redundant. In this paper, we present a new method exploiting this redundancy by factorizing PBGI data over the tree nodes. In particular, we show that a k‐means clustering in the parameter space of the spherical functions allows to define a small number of representative nodes against which any new one can be classified. These representative functions, gathered in a pre‐process over a subset of the actual points, form a look‐up table which allows to substitute node's data by quantized integers in a streaming process, avoiding building the full tree before compressing it. Depending on the nodes' spherical function variance in the scene and the desired accuracy, our indexed PBGI representation achieves between one and two orders of magnitude compression of the nodes spherical functions, with negligible numerical and perceptual error in the final image. In the case of a binary tree with one surfel per leaf and no spherical functions in the leaves, this leads to compression rates ranging from 3× to 5× for the whole tree.
Progressive Virtual Beam Lights
Authors: Novák Jan , Nowrouzezahrai Derek , Dachsbacher Carsten , Jarosz Wojciech
Published: July 2012

A recent technique that forms virtual ray lights (VRLs) from path segments in media, reduces the artifacts common to VPL approaches in participating media, however, distracting singularities still remain. We present Virtual Beam Lights (VBLs), a progressive many‐lights algorithm for rendering complex indirect transport paths in, from, and to media. VBLs are efficient and can handle heterogeneous media, anisotropic scattering, and moderately glossy surfaces, while provably converging to ground truth. We inflate ray lights into beam lights with finite thicknesses to eliminate the remaining singularities. Furthermore, we devise several practical schemes for importance sampling the various transport contributions between camera rays, light rays, and surface points. VBLs produce artifact‐free images faster than VRLs, especially when glossy surfaces and/or anisotropic phase functions are present. Lastly, we employ a progressive thickness reduction scheme for VBLs in order to render results that converge to ground truth.
Intrinsic Images by Clustering
Authors: Garces Elena , Munoz Adolfo , Lopez‐Moreno Jorge , Gutierrez Diego
Published: July 2012

Decomposing an input image into its intrinsic shading and reflectance components is a long‐standing ill‐posed problem. We present a novel algorithm that requires no user strokes and works on a single image. Based on simple assumptions about its reflectance and luminance, we first find clusters of similar reflectance in the image, and build a linear system describing the connections and relations between them. Our assumptions are less restrictive than widely‐adopted Retinex‐based approaches, and can be further relaxed in conflicting situations. The resulting system is robust even in the presence of areas where our assumptions do not hold. We show a wide variety of results, including natural images, objects from the MIT dataset and texture images, along with several applications, proving the versatility of our method.
Artistic Illumination Transfer for Portraits
Authors: Chen Xiaowu , Jin Xin , Zhao Qinping , Wu Hongyu
Published: July 2012

Relighting a portrait in a single image is still a challenging problem, particularly when only a single artistic reference photograph or painting is provided. In this paper, we propose an artistic illumination transfer system for portraits based on a database of portrait images (photographs and paintings) associated with hand‐drawn illumination templates (276) by artists. Users can select a reference portrait image in the database, and the corresponding illumination template is transferred to an input portrait using image warping. Users can also provide reference portrait images those are not in the database. Based on the Face Illumination Descriptor (FID), the system selects from the database the reference image with the closest illumination to that of the user‐provided reference image and adjusts the corresponding illumination template to match the contrast of the user‐provided reference image. Experiments on not only paintings but also photographs, paper‐cuts and sketches demonstrate that convincing illumination transferred results can be rendered by our system.
Matting and Compositing for Fresnel Reflection on Wavy Surfaces
Authors: Endo Yuki , Kanamori Yoshihiro , Fukui Yukio , Mitani Jun
Published: July 2012

This paper introduces a framework that can extract an alpha matte from a single image with Fresnel reflection, and that can composite other objects with the image such that plausible reflections are included. Our method handles reflections in a plane with small undulations, for example, a water surface with waves or a glossy tabletop. During the matting stage, our method first estimates the transmission color, which is assumed to be uniform, and then calculates a reflection image and alpha matte based on user markups. However, accurate extraction of the matte becomes challenging when a plane has small undulations because these create perturbations in the matte. We therefore propose a filter that can refine the matte effectively. In the compositing stage, the reflection of a composited object is synthesized by ray tracing in real time. We demonstrate the effectiveness of our method through comparisons with ground‐truth data and results using natural images as inputs.
Geometry Presorting for Implicit Object Space Partitioning
Authors: Eisemann M. , Bauszat P. , Guthe S. , Magnor M.
Published: July 2012

We present a new data structure for object space partitioning that can be represented completely implicitly. The bounds of each node in the tree structure are recreated at run‐time from the scene objects contained therein. By applying a presorting procedure to the geometry, only a known fraction of the geometry is needed to locate the bounding planes of any node. We evaluate the impact of the implicit bounding plane representation and compare our algorithm to a classic bounding volume hierarchy. Though the representation is completely implicit, we still achieve interactive frame rates on commodity hardware.
Parameterization‐Aware MIP‐Mapping
Authors: Manson Josiah , Schaefer Scott
Published: July 2012

We present a method of generating mipmaps that takes into account the distortions due to the parameterization of a surface. Existing algorithms for generating mipmaps assume that the texture is isometrically mapped to the surface and ignore the actual surface parameterization. Our method correctly downsamples warped textures by assigning texels weights proportional to their area on a surface. We also provide a least‐squares approach to filtering over these warped domains that takes into account the postfilter used by the GPU. Our method improves texture filtering for most models but only modifies mipmap generation, requires no modification of art assets or rasterization algorithms, and does not affect run‐time performance.
A Stylized Approach for Pencil Drawing from Photographs
Authors: Yang Heekyung , Kwon Yunmi , Min Kyungha
Published: July 2012

We present a stylized scheme that produces pencil drawings in a range of styles from an image. To produce controllable pencil drawing effects and remedy the problems of existing convolution‐based schemes, we develop a swing bilateral LIC (SBL) filter. Our first approach to express the styled pencil drawings is to control the directions of pencil strokes that depicts both shapes and smooth tone. Another approach is to produce colors of pencil drawings by sampling colors from real color pencils. The third approach is to mimic the artistic technique that increases the details of drawings in a progressive manner. We present drawings in several styles and compare some of them directly with illustrations taken from an artists' work.
Surface Relief Analysis for Illustrative Shading
Authors: Ammann Lucas , Barla Pascal , Guennebaud Gaël , Granier Xavier , Reuter Patrick
Published: July 2012

In this paper, we present an analysis technique that leverages the complexity found in detailed 3D models for illustrative shading purposes. Given a smooth base surface with relief, it locates relief features (concavities, convexities and inflections) around each surface point and at multiple scales, using cubic‐polynomial fitting. This object‐space, per‐vertex information is then used to guide a variety of shading techniques including normal enhancement, feature visualization, accessibility shading and radiance scaling. Thanks to this approach, features at multiple scales are easily combined, filtered and shaded, allowing users to explore surface relief in real‐time.