Low Anchor Research Articles

A GPS-less Framework for Localization and Coverage Maintenance in Wireless Sensor Networks

Sensing coverage is a fundamental issue for Wireless Sensor Networks (WSNs). Several coverage configuration protocols have been developed; most of them presume the availability of precise knowledge about each node location via GPS receivers. However, equipping each sensor node with a GPS is very expensive in terms of both energy and cost. On the other hand, several GPS-less localization algorithms that aim at obtaining nodes locations with a low cost have been proposed. Although their deep correlation, sensing coverage and localization have long been treated separately. In this paper, we analyze, design and evaluate a novel integrated framework providing both localization and coverage guarantees for WSNs. We integrate the well-known Coverage Configuration Protocol CCP with an improved version of the localization algorithm AT-Dist. We enhanced the original specification of AT-Dist in order to guarantee the necessary localization accuracy required by CCP. In our proposed framework, a few number of nodes are assumed to know their exact positions and dynamically vary their transmission ranges. The remaining sensors positions are derived, as accurately as possible, using this little initial location information. All nodes positions (exact and derived) are then used as an input for the coverage module. Extensive simulation results show that, even with a very low anchor density, our proposal reaches the same performance and efficiency as the ideal CCP based on complete and precise knowledge of sensors coordinates.

Efekt zakotwiczenia za pomocą przedmiotów nacechowanych w wymiarach wagi i wartości

The anchoring heuristic is a simplified strategy of decision making, in which anchor numbers affect numerical estimations. Comparing the target of estimation to a relatively low anchor number leads to a lower estimation than comparison to a relatively high anchor number. This effect is usually considered to be the result of using pure numbers, however numerical estimations can be affected by physical stimuli. In this study, we used items attributed in the context of weight and value. Comparing the anchor item characterized as light/heavy and cheap/expensive affects the subsequent estimations of weight and value of another item. Participants ( N = 160) were handed the anchor item to become familiar with it. After returning the anchor, they were handed another item to estimate its weight and value. The results suggest that the perception of weight influenced the estimations regarding weight, while the perception of value influenced the estimations of value. The results are discussed in the context of the anchoring mechanism based on self-generated anchors.

Internal Medicine residents use heuristics to estimate disease probability

Training in Bayesian reasoning may have limited impact on accuracy of probability estimates. In this study, our goal was to explore whether residents previously exposed to Bayesian reasoning use heuristics rather than Bayesian reasoning to estimate disease probabilities. We predicted that if residents use heuristics then post-test probability estimates would be increased by non-discriminating clinical features or a high anchor for a target condition. We randomized 55 Internal Medicine residents to different versions of four clinical vignettes and asked them to estimate probabilities of target conditions. We manipulated the clinical data for each vignette to be consistent with either 1) using a representative heuristic, by adding non-discriminating prototypical clinical features of the target condition, or 2) using anchoring with adjustment heuristic, by providing a high or low anchor for the target condition. When presented with additional non-discriminating data the odds of diagnosing the target condition were increased (odds ratio (OR) 2.83, 95% confidence interval [1.30, 6.15], p = 0.009). Similarly, the odds of diagnosing the target condition were increased when a high anchor preceded the vignette (OR 2.04, [1.09, 3.81], p = 0.025). Our findings suggest that despite previous exposure to the use of Bayesian reasoning, residents use heuristics, such as the representative heuristic and anchoring with adjustment, to estimate probabilities. Potential reasons for attribute substitution include the relative cognitive ease of heuristics vs. Bayesian reasoning or perhaps residents in their clinical practice use gist traces rather than precise probability estimates when diagnosing.

Oxygen Uptake At Criterion RPE In Trained And Untrained Females Following Exercise And Memory Anchoring

Exercise and memory anchoring provides a definitive anchoring procedure for linking perceptions of effort to variable intensities of physical exertion. However, it is unclear if relative intensity at a given RPE would remain consistent in individuals of different training status. PURPOSE: The current investigation compared percent of maximal oxygen uptake in recreationally trained (RT) versus untrained (UT) adult females at selected, criterion RPE during maximal, graded, treadmill exercise following exercise and memory anchoring to the Borg 15-category scale. METHODS: The RT (n = 8) group (21.8± 2.0 yrs.) and the UT (n = 3) group (18.0 ± 0.0 yrs.) each received anchoring instructions during a maximal, graded treadmill exercise test at an initial session. The low anchor was assigned a seven and the high anchor was assigned a 19 on the scale. At a second session, memory anchoring instructions were provided prior to a GXT during which RPE was recorded following each stage. Linear regression with RPE as the independent variable and oxygen consumption as the dependent variable was used to calculate percent VO2max for each criterion RPE (7, 9, 11, 13, 15 17, and 19). An independent samples t-test was used to compare percent VO2max between RT and UT at each criterion RPE. RESULTS: As expected, VO2max was higher for the RT than the UT. All other descriptive variables were similar between groups. Relative oxygen uptake at each criterion RPE was also similar. CONCLUSION: Pre-exercise exercise and memory anchoring yielded similar relative VO2 for young adult females independent of training status. It appears that exposure to the high and low anchors during the anchoring procedure is sufficient to guide exercise intensity during a maximal, graded, treadmill exercise test for this population. The current findings further validate Borg’s assumption for the application of a category scale in that the perceptual range may be set equal for all individuals as percent VO2max was similar between young, adult women of varying training status.

Shake Table Tests on Suspended Nonstructural Components Anchored in Cyclically Cracked Concrete

AbstractInsufficient anchorage of nonstructural components is a substantial cause of earthquake damage. To investigate this issue, shake table tests were conducted on model nonstructural components suspended and supported via anchors cast in cyclically cracked concrete. Concrete slabs supporting the anchored model component were subjected to seismic floor accelerations and corresponding floor-level cyclic crack width histories to simulate the anchor boundary conditions found in concrete structures during an earthquake. For these tests, post-installed anchors, namely, undercut and expansion types, were tested at various seismic demand levels. This paper presents this unique test data and illustrates important seismic anchor performance characteristics. For the investigated case, the measured correlation between anchor load and crack width indicated a low average anchor load level. In addition, the cumulative anchor displacements and achieved ultimate load capacities showed conservatism when compared with r...

Anchoring Revisited: The Role of the Comparative Question

When people estimate a numeric value after judging whether it is larger or smaller than a high or low anchor value (comparative question), estimates are biased in the direction of the anchor. One explanation for this anchoring effect is that people selectively access knowledge consistent with the anchor value as part of a positive test strategy. Two studies (total N = 184) supported the alternative explanation that people access knowledge consistent with their own answer to the comparative question. Specifically, anchoring effects emerged when the answer to the comparative question was unexpected (lower than the low anchor or higher than the high anchor). For expected answers (lower than the high anchor or higher than the low anchor), however, anchoring effects were attenuated or reversed. The anchor value itself was almost never reported as an absolute estimate.

Maximum load to failure and tensile displacement of an all-suture glenoid anchor compared with a screw-in glenoid anchor

The purpose of this study was to evaluate the biomechanical behavior of an all-suture glenoid anchor in comparison with a more conventional screw-in glenoid anchor, with regard to maximum load to failure and tensile displacement. All mechanical testing was performed using an Instron ElectroPuls E1000 mechanical machine, with a 10 N pre-load and displacement rate of 10 mm/min. Force-displacement curves were generated, with calculation of maximum load, maximum displacement, displacement at 50 N and stiffness. Pretesting of handset Y-Knots in bone analog models revealed low force displacement below 60 N of force. Subsequently, three groups of anchors were tested for pull out strength in bovine bone and cadaver glenoid bone: a bioabsorbable screw-in anchor (Bio Mini-Revo, ConMed Linvatec), a handset all-suture anchor (Y-Knot, ConMed Linvatec) and a 60 N pre-tensioned all-suture anchor (Y-Knot). A total of 8 anchors from each group was tested in proximal tibia of bovine bone and human glenoids (age range 50-90). In bovine bone, the Bio Mini-Revo displayed greater maximum load to failure (206 ± 77 N) than both the handset (140 ± 51 N; P = 0.01) and the pre-tensioned Y-Knot (135 ± 46 N; P = 0.001); no significant difference was seen between the three anchor groups in glenoid bone. Compared to the screw-in anchors, the handset all-suture anchor displayed inferior fixation, early displacement and greater laxity in the bovine bone and cadaveric bone (P < 0.05). Pre-tensioning the all-suture anchor to 60 N eliminated this behavior in all bone models. Handset Y-Knots display low force anchor displacement, which is likely due to slippage in the pilot hole. Pre-tensioning the Y-Knot to 60 N eliminates this behavior. I.

Shaping Tension Structures with Actively Bent Linear Elements

To achieve sufficient anticlastic (negative) curvature, membrane structures are tensioned between high and low anchor points, attached to the ground, buildings or poles. By integrating flexible bending elements in the membrane surface, an internal support and shape-defining system is created that provides more freedom in design and allows reducing the amount of external supports compared to traditional membrane structures. This paper presents a computational framework for form finding of tension structures with integrated, elastically bent, linear elements, based on three-dimensional bending moment vectors and a mixed force density formulation. With an implementation of this framework in CAD modelling software, users can control form and forces by prescribing any combination of force densities, forces, stiffness or lengths to the spline and cable-net elements. Sparse matrix operations are used to compute the resulting equilibrium shapes. The shape-defining possibilities of integrating ‘bending-active’ elements in tension structures are demonstrated through a series of design studies with various boundary conditions and spline configurations. The presented framework and implementation provide a straightforward method for the design of this hybrid structural system, and, therefore, facilitate its further exploration.

Anchoring effects on prospective and retrospective metacomprehension judgments as a function of peer performance information

Two experiments were conducted to investigate anchoring effects on metacomprehension judgments as a function of fictitious information participants received about past peer performance. In Experiment 1 participants were randomly assigned to one of the three anchor groups that, in some cases, provided past peer performance averages in terms of a percentage: a high anchor (85%) a low anchor (55%), and no anchor. Results showed that relative to the no anchor group, the low anchor group made significantly lower prospective judgments whereas the high anchor group did not make significantly higher prospective judgments. With a high anchor of greater magnitude (95%), Experiment 2 demonstrated more pronounced anchoring effects on prospective judgments: Relative to the no anchor group, the low anchor group made significantly lower judgments and the high anchor group made significantly higher judgments. In addition, Experiment 2 showed that anchoring effects occurred even on retrospective judgments. Overall, the results showed that peer performance information can serve as an anchoring point for metacomprehension judgments and the anchoring effects are tenacious given that they can even affect retrospective judgments of performance.

Effect of outdoor temperature, heat primes and anchoring on belief in global warming

It is generally acknowledged that global warming is occurring, yet estimates of future climate change vary widely. Given this uncertainty, when asked about climate change, it is likely that people’s judgments may be affected by heuristics and accessible schemas. Three studies evaluated this proposition. Study 1 revealed a significant positive correlation between the outdoor temperature and beliefs in global warming. Study 2 showed that people were more likely to believe in global warming when they had first been primed with heat-related cognitions. Study 3 demonstrated that people were more likely to believe in global warming and more willing to pay to reduce global warming when they had first been exposed to a high vs. a low anchor for future increases in temperature. Together, results reveal that beliefs about global warming (and willingness to take actions to reduce global warming) are influenced by heuristics and accessible schemas. Several practical implications are discussed.

Peculiar velocities into the next generation: cosmological parameters from the SFI++ survey

We present cosmological parameter constraints from the SFI++ galaxy peculiar velocity survey, the largest galaxy peculiar velocity sample to date. The analysis is performed by using the gridding method developed in Abate et al. (2008). We concentrate on constraining parameters which are affected by the clustering of matter: sigma_8 and the growth index gamma. Assuming a concordance LCDM model we find sigma_8=0.91+0.22-0.18 and gamma=0.55+0.13-0.14 after marginalising over Omega_m. These constraints are consistent with, and have similar constraining power to, the same constraints from other current data sets which use different methods. Recently there have been several claims that the peculiar velocity measurements do not agree with LCDM. We find instead although a higher value of sigma_8 and a lower value of Omega_m are preferred, the values are still consistent when compared with WMAP5. We note that although our analysis probes a variety of scales, the constraints will be dominated by the smaller scales, which have the smallest uncertainties. These results show that peculiar velocity analysis is a vital probe of cosmology, providing competitive constraints on parameters such as sigma_8. Its sensitivity to the derivative of growth function, particularly down to redshift zero, means it can provide a vital low redshift anchor on the evolution of structure formation. The importance of utilising different probes with varying systematics is also an essential requirement for providing a consistency check on the best-fitting cosmological model.

Overconfidence in absolute and relative performance: The regression hypothesis and Bayesian updating

Studies have found that people are overconfident in estimation involving difficult tasks but underconfident in easy tasks. Conversely, they are overconfident in placing themselves in easy tasks but underconfident in hard tasks. These findings can be explained by a regression hypothesis that implies random errors in estimation as well as by rational Bayesian updating (that implies no random error). We test these hypotheses in five experiments. We find overconfidence in estimation involving hard tasks but underconfidence in easy tasks. However, for placement (involving both easy and hard tasks) we find no overconfidence, regression effects due to low and high anchor points, and extreme underconfidence when people choose between multiple alternatives. On the other hand, when given precise information about absolute performance, people’s re-assessments of relative performance are consistent with the Bayesian model. Since placement judgments are important in many competitive settings, our results emphasize the need for more research to identify their determinants.

Ratings of perceived exertion and oxygen consumption during maximal, graded, treadmill exercise following different anchoring procedures

In this study, relative oxygen consumption (VO2) was compared at selected criterion ratings of perceived exertion (RPE) during maximal, graded, treadmill exercise following memory or combined exercise and memory anchoring to the Borg 15-category scale. The purpose was to determine whether participants would produce a similar relative VO2 at a corresponding criterion RPE following different types of anchoring. Thirty-six college-aged participants (18 males, 18 females) volunteered for this investigation and were assigned to one of two groups: a memory anchoring group or a combined exercise and memory group. The memory anchoring group received only verbal instructions before the experimental trial. The combined exercise and memory group received identical verbal instructions to the memory anchoring group, which were administered initially while the participants performed a graded treadmill test to exhaustion. The low perceptual anchor (i.e. 7) was established during light walking and the high perceptual anchor (i.e. 19) at volitional exhaustion. Similar to that for the memory anchoring group, the memory anchoring instructions were presented immediately before the experimental trial for the combined exercise and memory group. Linear regression was used to calculate percent VO2peak for each criterion RPE (7, 9, 11, 13, 15, 17, and 19). Independent samples t-tests were used to compare percent VO2peak between the two groups at each criterion RPE. Percent VO2peak did not differ (P>0.05) between the two groups at any criterion RPE. Both types of anchoring instructions can be considered valid tools in applying the Borg scale to this population Memory anchoring may be preferred because it involves one less laboratory session for both the investigator and the participant.

When knowledge matters—differential effects of available knowledge in standard and basic anchoring tasks

AbstractThe present research examines whether anchoring effects—the assimilation of a numeric estimate towards a previously considered standard—depend on judges' available knowledge in the target domain. Based on previous research, I distinguish two types of anchoring effects. Standard anchoring is obtained if judges are explicitly asked to compare the anchor to the target. Basic anchoring results if the accessibility of the anchor is increased prior to judgments about the target. I expected that only basic but not standard anchoring is reduced by providing judges with judgment‐relevant knowledge. Using a standard versus basic anchoring paradigm, 112 participants were confronted with a high versus low anchor before estimating the average price of a German midsize car. Prior to this task, participants were provided with information about prices of cars (relevant knowledge) versus kitchens (irrelevant knowledge). Results demonstrate that this knowledge only influenced the magnitude of basic but not standard anchoring effects. This finding demonstrates that knowledge has differential effects in different types of anchoring. Copyright © 2007 John Wiley &amp; Sons, Ltd.

Behavior of Giant Vesicles with Anchored DNA Molecules

We study changes in curvature and elastic properties of lipid membranes induced by anchoring of long hydrophilic polymers at low polymer surface concentrations (corresponding to the mushroom regime). The effect of anchored polymers on the membrane spontaneous curvature is characterized by monitoring the changes in the fluctuation spectra and the morphology of giant unilamellar vesicles. The polymers used in our study are fluorescently labeled and biotinylated λ-phage DNA molecules which bind to biotinylated giant unilamellar vesicles via a biotin-avidin-biotin linkage. By varying the amount of biotinylated lipid in the membrane, we control the surface concentration of anchors. At low anchor concentrations, the spontaneous curvature of the membrane increases linearly with the DNA concentration. The linear increase is consistent with theoretical predictions for polymer surface concentrations in the mushroom regime. At higher anchor concentrations, which should still belong to the mushroom regime, the vesicles undergo budding transitions. In this latter regime, the bud size is used to estimate the polymer-induced membrane curvature.

The long and short of it: physical anchoring effects

AbstractAttempts to reconstruct the magnitude of recently encountered physical stimuli were influenced by the provision of physical anchors. Whether estimating length, weight, or loudness, those increasing the magnitude of a relatively small (short, light, or quiet) physical anchor produced estimates that were reliably lower than did those decreasing the magnitude of a relatively large (long, heavy, or loud) anchor. Estimates produced without an anchor were also low, suggesting that when people physically adjust upwards from a self‐selected starting point, “no anchor” may, in fact, act as a very low anchor. Physical anchors appear to influence estimates of recently encountered physical stimuli, much as numerical anchors influence estimates of more abstract numerical quantities. Implications for processes underlying anchoring, adjustment, and related tasks are discussed. Copyright © 2006 John Wiley &amp; Sons, Ltd.

Does “000,000” matter? Psychological effects of Turkish monetary reform

Turkish monetary reform, which took effect in January 2005, introduced the New Turkish Lira (NTL) by deleting six zeros from the former currency, the Turkish Lira (TL). Two experiments investigated how the introduction of the NTL might affect price estimation. In the first, conducted in December 2004, 202 students were first presented with high or low anchor values and then estimated the average price of a “new Turkish mid-sized car” in different currencies (TL, NTL and Euro). Although anchoring bias was not significantly different across familiar (TL) and unfamiliar currencies (NTL and Euro), price estimates in Euro and NTL were significantly higher than those in TL. In the second experiment, carried out 6 months later, 212 adult consumers estimated the prices of 13 items in one of three currencies. For five items prices estimated in Euros were significantly higher than those expressed in either TL or NTL. However, there were no significant differences between TL and NTL, suggesting that Turkish consumers had quickly adapted. Such ease of adaptation is consistent with a rescaling hypothesis: when one or more zeros are dropped from a currency, consumers rescale all prices relatively quickly rather than relearn them selectively through gradual exposure.

Correlated fluctuations in luminosity distance and the importance of peculiar motion in supernova surveys

Large scale structure introduces two different kinds of errors in the luminosity distance estimates from standardizable candles such as supernovae Ia (SNe)--a Poissonian scatter for each SN and a coherent component due to correlated fluctuations between different SNe. Increasing the number of SNe helps reduce the first type of error but not the second. The coherent component has been largely ignored in forecasts of dark energy parameter estimation from upcoming SN surveys. For instance it is commonly thought, based on Poissonian considerations, that peculiar motion is unimportant, even for a low redshift SN survey such as the Nearby Supernova Factory (SNfactory; z=0.03-0.08), which provides a useful anchor for future high redshift surveys by determining the SN zero point. We show that ignoring coherent peculiar motion leads to an underestimate of the zero-point error by about a factor of 2, despite the fact that SNfactory covers almost half of the sky. More generally, there are four types of fluctuations: peculiar motion, gravitational lensing, gravitational redshift and what is akin to the integrated Sachs-Wolfe effect. Peculiar motion and lensing dominates at low and high redshifts, respectively. Taking into account all significant luminosity distance fluctuations due to large scale structure leads to amore » degradation of up to 60% in the determination of the dark energy equation of state from upcoming high redshift SN surveys, when used in conjunction with a low redshift anchor such as the SNfactory. The most relevant fluctuations are the coherent ones due to peculiar motion and the Poissonian ones due to lensing, with peculiar motion playing the dominant role. We also discuss to what extent the noise here can be viewed as a useful signal, and whether corrections can be made to reduce the degradation.« less

Playing Dice With Criminal Sentences: The Influence of Irrelevant Anchors on Experts’ Judicial Decision Making

Judicial sentencing decisions should be guided by facts, not by chance. The present research however demonstrates that the sentencing decisions of experienced legal professionals are influenced by irrelevant sentencing demands even if they are blatantly determined at random. Participating legal experts anchored their sentencing decisions on a given sentencing demand and assimilated toward it even if this demand came from an irrelevant source (Study 1), they were informed that this demand was randomly determined (Study 2), or they randomly determined this demand themselves by throwing dice (Study 3). Expertise and experience did not reduce this effect. This sentencing bias appears to be produced by a selective increase in the accessibility of arguments that are consistent with the random sentencing demand: The accessibility of incriminating arguments was higher if participants were confronted with a high rather than a low anchor (Study 4). Practical and theoretical implications of this research are discussed.

Subliminal anchoring: The effects of subliminally presented numbers on probability estimates

Previous research demonstrated that if attention is paid to a supraliminally presented number, a subsequent quantitative estimate assimilates towards this number (the anchor effect). One explanation states that this effect is merely caused by the heightened accessibility level of the anchor value itself. Based on this numeric priming account and generalizing from subliminal priming studies, we expected a short-lived subliminal anchor effect. We presented participants subliminally with a low or high anchor value (10 or 90) and next they had to estimate the probability of an epidemic. Half of them were pressed to do this quickly. Only under time pressure, a significant anchor effect emerged.