List Length Research Articles

On the facial Thue choice index of plane graphs

Let G be a plane graph, and let φ be a colouring of its edges. The edge colouring φ of G is called facial non-repetitive if for no sequence r1,r2,…,r2n, n≥1, of consecutive edge colours of any facial path we have ri=rn+i for all i=1,2,…,n. Assume that each edge e of a plane graph G is endowed with a list L(e) of colours, one of which has to be chosen to colour e. The smallest integer k such that for every list assignment with minimum list length at least k there exists a facial non-repetitive edge colouring of G with colours from the associated lists is the facial Thue choice index of G, and it is denoted by πfl(G). In this article we show that πfl′(G)≤291 for arbitrary plane graphs G. Moreover, we give some better bounds for special classes of plane graphs.

Partial MAP-based lattice reduction-aided list MIMO detection

The partial maximum a posteriori probability (MAP) principle allows a decision on the list length of the list-based MIMO detection at a certain SNR to provide near optimal performance. The computationally efficient lattice reduction (LR) is adopted with the partial MAP-based list detection, where the column reordering criterion (CRC) is carried out to further reduce the list length and complexity.

Fastlegepasienters bruk av legevakt

Norwegian emergency medical services are used with frequency, often in relation to conditions that could wait until the next day to be handled by the patient's regular GP (RGP). We investigated whether there are characteristics of particular GPs that may help explain why patients on their list use the emergency medical services. We used data from the billing cards for 2008 from all emergency doctors, linked to information from the Regular GP database and Statistics Norway, for a total of 4,097 RGPs. For each RGP we estimated a contact rate: The total number of contacts reported for their list patients (identified by their personal ID numbers), divided by the length of the RGP's list. This rate was subsequently analysed with regard to characteristics of the RGP (bivariate analyses and multiple logistic regression). The average contact rate amounted to 27.4 contacts per 100 list patients, with significant variation between the RGPs (the 25th percentile was 17.8 contacts and the 75th percentile 33.1). Patients of male RGPs, young RGPs and immigrant RGPs used the emergency medical services more frequently than patients of female RGPs, older RGPs and Norwegian RGPs. Patients from long lists, single-doctor practices and open lists used the emergency medical services less frequently than patients from short lists, group practices and closed lists. The contact rate was higher in rural municipalities than in urban areas. The large variations in the use of emergency medical services indicate that more RGPs should take measures to improve accessibility for emergency calls during the daytime.

Changes in response bias with different study-test delays: Evidence from young adults, older adults, and patients with Alzheimer's disease.

Along with impaired discrimination, patients with Alzheimer's disease (AD) often show an abnormally liberal response bias (greater tendency to respond "old"). Previously we matched discrimination by varying study-test list length and found that participants' usual bias is maintained, such that patients with AD were more liberal than healthy controls. However, this pattern could be a result of the way in which discrimination was matched. In this experiment, we examined whether matching discrimination with the use of a delay would lead to a liberal response bias in healthy younger and older adults as it might lead to the use of more similar memorial processing to the patients with AD. Younger adults, older adults, and patients with AD were run in 2 study-test sessions, with study and recognition test separated by either a 1-min or 1-day delay. With the 1-min delay, both younger adults and healthy older adults showed a conservative response bias, while patients with AD showed a liberal response bias. When discrimination was matched between patients with AD and controls by the use of a delay, response bias was also matched, with all participants showing a more liberal response bias. The current study suggests that how discrimination is matched between patients with AD and controls matters greatly. Potentially, this liberal bias is a result of healthy younger and older adults relying primarily on familiarity at the longer delay, thus using more similar memorial processes to patients with AD who are dependent on familiarity at any delay.

Models of verbal working memory capacity: what does it take to make them work?

Theories of working memory (WM) capacity limits will be more useful when we know what aspects of performance are governed by the limits and what aspects are governed by other memory mechanisms. Whereas considerable progress has been made on models of WM capacity limits for visual arrays of separate objects, less progress has been made in understanding verbal materials, especially when words are mentally combined to form multiword units or chunks. Toward a more comprehensive theory of capacity limits, we examined models of forced-choice recognition of words within printed lists, using materials designed to produce multiword chunks in memory (e.g., leather brief case). Several simple models were tested against data from a variety of list lengths and potential chunk sizes, with test conditions that only imperfectly elicited the interword associations. According to the most successful model, participants retained about 3 chunks on average in a capacity-limited region of WM, with some chunks being only subsets of the presented associative information (e.g., leather brief case retained with leather as one chunk and brief case as another). The addition to the model of an activated long-term memory component unlimited in capacity was needed. A fixed-capacity limit appears critical to account for immediate verbal recognition and other forms of WM. We advance a model-based approach that allows capacity to be assessed despite other important processing contributions. Starting with a psychological-process model of WM capacity developed to understand visual arrays, we arrive at a more unified and complete model.

The Consequences of Predicting Scientific Impact in Psychology Using Journal Impact Factors

An academic journal’s impact factor (hereafter JIF) is an average measure of the citation count of individual articles published in that journal. JIF is used to assess merit, predict impact, and allocate resources, but the actual number of citations to individual articles is only modestly correlated with the JIFs of the journals in which they are published. We counted PsycInfo citations to 1,133 articles published in nine leading psychology journals (1996–2005). Both article length (r =.31) and reference list length (r = .41) predicted log-transformed citation counts better than JIF (r = .27). Articles with fewer graphs and more structural equation models were more frequently cited. Citation count was better predicted by a model based on article length and citation count rather than JIF. When JIF was used to predict citation count, the impact of women authors and social science research was underestimated. These findings distinguish impact in science, as measured by JIF, from actual impact in psychology, and they show the unintended consequences of using a measure of the former to predict the latter.

Hvilke fastleger deltar i legevakt?

Approximately half of all accident and emergency medical (A&E) services are provided by regular general practitioners (RGPs). We wished to find out which RGPs staff the A&E services. The material comprises billing cards from all A&E doctors in 2008, linked to information from Statistics Norway and the Regular GP database. We estimated the proportion of various RGPs who staff the A&E roster and how many patient contacts they had while on duty. The same variables describing the RGPs were used in a multivariate logistic regression analysis, in which the dependent variable was whether the RGPs were on the emergency service roster or not. Altogether 53% of the RGPs were on the emergency service roster, and accounted for 47% of all patient contacts. The RGPs were older than other emergency doctors (44 years as opposed to 34 years), and included a smaller proportion of women (33% as opposed to 44%). Immigrants accounted for 23% of the RGPs and 21% of the other emergency doctors. Women RGPs were on A&E duty less frequently than their male counterparts in all age groups, and they also had fewer patient contacts (206 and 374). The participation rate decreased in proportion to the doctors' age, increasing list length and increasing centrality. Immigrant RGPs with a short time of residence in Norway had the highest frequency of on-call duty (81%). The number of women RGPs is increasing, and it is therefore likely that the frequency of on-call duty among RGPs will decrease further. However, the immigrants are providing a significant contribution to maintaining the A&E scheme.

Research Area: Learning

Motor-function encoding action phrases, facilitates recollection more than verbal encoding (enactment effect, c.f. Nilsson, 2000). Further, if the phrases are intended to be recalled via motor-function encoding it also leads to higher memory accessibility, referred to as the intention-superiority effect (Goschke & Kuhl, 1993) or the intended enactment effect (Freeman & Ellis, 2003), depending on whether the same process or different processes are assumed to underlie both effects. In three experiments, both effects were studied as a function of list length (18, 30, 60, or 90 items), retrieval measures (free recall, cued recall and recognition). Additionally, different moderator variables for these effects were investigated (familiarity, degree of motor involvement of the action phrases, individual differences in action orientation). Similar effects of intended and actual enactment were found for memory accuracy and accessibility (i.e., response latencies), but the effects were moderated by the nature of the action phrase and action orientation. State-oriented individuals and highly motoric action phrases showed a pronounced (intended) enactment effect. The results, at least partially, support a common explanation for both effects.

Phonological false memories in children and adults: Evidence for a developmental reversal

False memories created by the Deese/Roediger–McDermott (DRM) procedure typically show a developmental reversal whereby levels of false recall increase with age. In contrast, false memories produced by phonological lists have been shown to decrease as age increases. In the current study we show that phonological false memories, like semantic false memories produced by the DRM procedure, show a developmental reversal when list items converge on a single critical lure. In addition, effects of list length were observed in adults and older children but not in the younger children, again mirroring effects previously observed in semantic false memories. These findings suggest that differences in list structure underlie the divergent developmental trajectories previously reported in semantic and phonological false memories. The findings are discussed in relation to theories of false memory and theories of spoken word recognition.

The role of stimulus type in list length effects in recognition memory

While many studies have investigated the list length effect in recognition memory, few have done so with stimuli other than words. This article presents the results of four list length experiments that involved word pairs, faces, fractals, and photographs of scenes as the stimuli. A significant list length effect was identified when faces and fractals were the stimuli, but the effect was nonsignificant when the stimuli were word pairs or photographs of scenes. These findings suggest that the intrastimulus similarity is what dictates whether list length has a significant effect on recognition performance. As is the case with words, word pairs and photographs of scenes are not sufficiently similar to generate detectable item interference.

Temporal–contextual processing in working memory: Evidence from delayed cued recall and delayed free recall tests

Three experiments are reported that addressed the nature of processing in working memory by investigating patterns of delayed cued recall and free recall of items initially studied during complex and simple span tasks. In Experiment 1, items initially studied during a complex span task (i.e., operation span) were more likely to be recalled after a delay in response to temporal-contextual cues, relative to items from subspan and supraspan list lengths in a simple span task (i.e., word span). In Experiment 2, items initially studied during operation span were more likely to be recalled from neighboring serial positions during delayed free recall than were items studied during word span trials. Experiment 3 demonstrated that the number of attentional refreshing opportunities strongly predicts episodic memory performance, regardless of whether the information is presented in a spaced or massed format in a modified operation span task. The results indicate that the content-context bindings created during complex span trials reflect attentional refreshing opportunities that are used to maintain items in working memory.

Associative information in memory: Evidence from cued recall

The representation of item and associative information in episodic memory was investigated using cued recall and single item recognition. In the first four experiments, participants studied two lists constructed such that some items presented in a pair during List 1 were rearranged to create new pairs in List 2 and were accompanied by pairs exclusive to List 2. List 1 was composed of either word–face pairs (Experiment 1 and 3) or word–word and face–face pairs (Experiment 2 and 4). Participants were tested for their memory of the second list containing only word-face pairs. When the test required associative information (i.e., cued recall), interference was specific to pair-type. Specifically, repeating items in the same pair-type across lists led to a greater number of correct and incorrect responses but repeating items in different pair-types did not change performance. When the test did not require associative information (i.e., single item recognition), interference was not specific to pair-type; hits and false alarms were higher for items presented on List 1. In the final experiment, the number of studied pairs and single items was independently manipulated and a pair-specific list length effect was observed. That is, performance in cued recall was modulated by the number of studied pairs, but not the number of studied individual items. Together, these data suggest that information specific to the pair-type (i.e., associative information) is stored and strategically utilized during memory search.

Direct estimation of cause-specific mortality fractions from verbal autopsies: multisite validation study using clinical diagnostic gold standards

BackgroundVerbal autopsy (VA) is used to estimate the causes of death in areas with incomplete vital registration systems. The King and Lu method (KL) for direct estimation of cause-specific mortality fractions (CSMFs) from VA studies is an analysis technique that estimates CSMFs in a population without predicting individual-level cause of death as an intermediate step. In previous studies, KL has shown promise as an alternative to physician-certified verbal autopsy (PCVA). However, it has previously been impossible to validate KL with a large dataset of VAs for which the underlying cause of death is known to meet rigorous clinical diagnostic criteria.MethodsWe applied the KL method to adult, child, and neonatal VA datasets from the Population Health Metrics Research Consortium gold standard verbal autopsy validation study, a multisite sample of 12,542 VAs where gold standard cause of death was established using strict clinical diagnostic criteria. To emulate real-world populations with varying CSMFs, we evaluated the KL estimations for 500 different test datasets of varying cause distribution. We assessed the quality of these estimates in terms of CSMF accuracy as well as linear regression and compared this with the results of PCVA.ResultsKL performance is similar to PCVA in terms of CSMF accuracy, attaining values of 0.669, 0.698, and 0.795 for adult, child, and neonatal age groups, respectively, when health care experience (HCE) items were included. We found that the length of the cause list has a dramatic effect on KL estimation quality, with CSMF accuracy decreasing substantially as the length of the cause list increases. We found that KL is not reliant on HCE the way PCVA is, and without HCE, KL outperforms PCVA for all age groups.ConclusionsLike all computer methods for VA analysis, KL is faster and cheaper than PCVA. Since it is a direct estimation technique, though, it does not produce individual-level predictions. KL estimates are of similar quality to PCVA and slightly better in most cases. Compared to other recently developed methods, however, KL would only be the preferred technique when the cause list is short and individual-level predictions are not needed.

Sensitivity and Test-Retest Reliability of the International Shopping List Test in Assessing Verbal Learning and Memory in Mild Alzheimer's Disease

The International Shopping List Test (ISLT) was developed specifically to assess verbal list learning and memory in people from different language and cultural backgrounds. In this paper, we describe three studies that examined the sensitivity and reliability of the ISLT in assessing verbal list learning and memory impairment in English-speaking people with mild Alzheimer's disease (AD) and evaluated whether measures of retention-weighted recall (RWR) provided greater sensitivity and/or reliability relative to conventional list learning performance measures (e.g., free recall). In Study 1, we compared ISLT performance between patients with AD and matched controls and found that AD patients showed a large magnitude impairment on all ISLT performance measures (Cohen's d values >2). The RWR measure was more sensitive to detecting AD-related impairment than the free recall measure for Trial 1, although the most sensitive measures of the ISLT were free recall from Trial 3 and delayed recall. In Study 2, we compared RWR and free recall measures between 10- and 12-word versions of the ISLT, but found no difference between performance measures for the different list lengths. In Study 3, we evaluated test-retest reliabilities of the different outcome measures derived from the ISLT and found that measures of free recall had higher reliabilities than the RWR measures. Taken together, results of these studies suggest that measures of total free recall during learning trials and delayed recall from the 12-word version of the ISLT provide the greatest sensitivity to detecting verbal list learning and memory impairment in AD and that this task shows good test-retest reliability.

Abstract 4109: A 5-gene signature (sig) predicts clinical benefit from erlotinib in non-small cell lung cancer (NSCLC) patients (pts) harboring wild-type (wt) EGFR & KRAS

Abstract Background: Despite a low response rate, erlotinib (E) improves survival in a subset of NSCLC pts with wt EGFR but there are no established markers for identifying pts likely to have clinical benefit. We hypothesized that a gene expression sig could be used for this purpose. Material and Methods: We used pretreatment gene expression profiles (Affymetrix HG1.0ST) from 101 chemo-refractory pts in our Biomarkers-Integrated Approaches of Targeted Therapy for Lung Cancer Elimination (BATTLE) treated with E, E+bexarotene (EB), sorafenib (S), or vandetanib (V). 24 cases of wt EGFR & KRAS tumors treated with E or EB were compared to train the signature (two-sided t-test), using the primary end-point of the trial [8-week disease control (8wDC)]. Principal component (PC) analysis and a logistic regression model were used to develop the sig. Gene expression profiles from 108 NSCLC cell lines (Illumina), with available E IC50 (N=94) and DNA methylation profiling (N=66, Illumina), were used for in vitro studies. Results: 113 genes were differentially expressed between pts with or without 8wDC (false discovery rate 30%; P=0.004). Leave-one-out cross validation with various gene list lengths produced a 5-gene sig, including lipocalin 2 (LCN2), with a specificity, sensitivity and accuracy of 80% to predict 8wDC. In pts treated with E or EB, using the median sig score, the 8wDC rate in the sig-positive group was 83% compared with 0% in the sig-negative group; the sig did not predict 8wDC in pts treated with S or V (Mantel-Haenszel chi-squared test P=0.023). The improvement in 8wDC in the sig-positive group translated to an increased progression-free survival (PFS) (hazard ratio=0.12, 95% confidence interval: 0.03-0.46, P=0.001; log-rank P=0.0004; median PFS: 12.5 weeks vs. 7.2 weeks). We tested the sig in an independent set of 47 wt EGFR&KRAS cell lines. It predicted E sensitivity with an area under the curve of 78% (P=0.002). The first PC of the sig and the IC50 for E were correlated (r=−0.47, P=0.0009). In 108 NSCLC cell lines, LCN2 gene expression was bimodal and correlated with the IC50 for E (r=−0.46, P=0.001). Degree of methylation and expression level of LCN2 were inversely in wt EGFR & KRAS NSCLC cells (r=−0.79, P<0.0001, N=33). Cell lines with completely unmethylated LCN2 were more sensitive to E compared to those with LCN2 full methylation (N=36) (P=0.006); the difference remained significant in wt EGFR & KRAS cell lines (P=0.014). Conclusion: We identified a 5-gene sig predictive of PFS benefit in NSCLC pts with wt EGFR & KRAS treated with E, but not S or V The sig was also predictive of E sensitivity in vitro. LCN2 was the strongest individual marker of sensitivity and may be epigenetically regulated. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4109. doi:10.1158/1538-7445.AM2011-4109

Managing the tabu list length using a fuzzy inference system: an application to examination timetabling

In this paper, we present an application of Tabu Search (TS) to the examination timetabling problem. One of the drawbacks of this meta-heuristic is related to the need of tuning some parameter (like tabu tenure) whose value affects the performance of the algorithm. The importance of developing an automatic procedure is clear considering that most of the users of timetabling software, like academic staff, do not have the expertise to conduct such tuning. The goal of this paper is to present a method to automatically manage the memory in the TS using a Decision Expert System. More precisely a Fuzzy Inference Rule Based System (FIRBS) is implemented to handle the tabu tenure based on two concepts, “Frequency” and “Inactivity”. These concepts are related respectively with the number of times a move is introduced in the tabu list and the last time (in number of iterations) the move was attempted and prevented by the tabu status. Computational results show that the implemented FIRBS handles well the tuning of the tabu status duration improving, as well, the performance of Tabu Search.

Paying the extinction debt: woodland birds in the Mount Lofty Ranges, South Australia

Approximately 90% of the original woodlands of the Mount Lofty Ranges of South Australia has been cleared, modified or fragmented, most severely in the last 60 years, and affecting the avifauna dependent on native vegetation. This study identifies which woodland-dependent species are still declining in two different habitats, Pink Gum—Blue Gum woodland and Stringybark woodland. We analyse the Mount Lofty Ranges Woodland Bird Long-Term Monitoring Dataset for 1999–2007, to look for changes in abundance of 59 species. We use logistic regression of prevalence on lists in a Bayesian framework, and List Length Analysis to control for variation in detectability. Compared with Reporting Rate Analysis, a more traditional approach, List Length Analysis provides tighter confidence intervals by accounting for changing detectability. Several common species were declining significantly. Increasers were generally large-bodied generalists. Many birds have already disappeared from this modified and naturally isolated woodland island, and our results suggest that more specialist insectivores are likely to follow. The Mount Lofty Ranges can be regarded as a ‘canary landscape’ for temperate woodlands elsewhere in Australia—without immediate action their bird communities are likely to follow the trajectory of the Mount Lofty Ranges avifauna. Alternatively, with extensive habitat restoration and management, we could avoid paying the extinction debt.

The Extended k-tree Algorithm

Consider the following problem: Given k=2q random lists of n-bit vectors, L 1,…,L k , each of length m, find x 1∈L 1,…,x k ∈L k such that x 1+⋅⋅⋅+x k =0, where + is the XOR operation. This problem has applications in a number of areas, including cryptanalysis, coding theory, finding shortest lattice vectors, and learning theory. The so-called k-tree algorithm, due to Wagner, solves this problem in \(\tilde{O}(2^{q+n/(q+1)})\) expected time provided the length m of the lists is large enough, specifically if m≥2n/(q+1).In many applications, however, it is necessary to work with lists of smaller length, where the above algorithm breaks down. In this paper we generalize the algorithm to work for significantly smaller values of the list length m, all the way down to the threshold value for which a solution exists with reasonable probability. Our algorithm exhibits a tradeoff between the value of m and the running time. We also provide the first rigorous bounds on the failure probability of both our algorithm and that of Wagner.As a third contribution, we give an extension of this algorithm to the case where the vectors are not binary, but defined over an arbitrary finite field \(\mathbb{F}_{r}\), and a solution to λ 1 x 1+⋅⋅⋅+λ k x k =0 with \(\lambda_{i} \in \mathbb{F}_{r}^{*}\) and x i ∈L i is sought.

Use of briefings and debriefings as a tool in improving team work, efficiency, and communication in the operating theatre

IntroductionTeam work, communication, and efficiency in the operating theatre are widely recognised to be suboptimal. Poor communication is the single biggest cause of medical error. The surgical operating theatre is...

The chair's report on SIGMOD'10 demonstration program

Submission and review process. We had a total of 95 submissions, up from 86 last year. Each submission had no more than 4 pages, one more than last year. Unlike research-paper submissions (which were subject to double-blind reviewing), each demo paper had the full author list exposed. This tradition, which was followed in all the preceding SIGMOD conferences, is mainly because, in general, it is difficult, sometime even awkward, to achieve anonymity of systems, many of which are long-term projects with a homepage, and thus, is easily identifiable with Google. The review process was quite standard. Each submission was refereed by three reviewers. Papers with unanimous positive (negative) ratings from all reviewers were immediately accepted (rejected). The rest (i.e., those with conflicts) then went through a discussion phase. The competition turned out to be rather heated. The high quality of the submissions rendered rejection a painful decision to make. We therefore decided not to limit the length of the acceptance list, but accept a paper as long as (i) its average rating was at least “weak accept”, and (ii) it was championed by at least one reviewer. Eventually, 35 demos were accepted, giving an acceptance rate of 36.8%.