Worse Characteristics Research Articles

Clustering of objects with poorly formalizable features based on a neural network in the form of Kohonen layers

Analysis of profiles of minors in social networks shows that teenagers indicate in them information that increases the level of their social desirability. Such information often does not correspond to the real behavior of the teenager. For a full analysis of the level of deviance of a minor need tools covering the full range of indicators. In contrast to the usual approach to clustering objects based on their Association in groups by the criterion of the minimum distance in multidimensional space when clustering features it is advisable to take into account their proximity to the methods of obtaining information and methods of processing of this information by the inspector for minors. In the first phase of the study is the clustering of signs of deviation, the second the determination of the weighting factors of indicator of the degree of deviance within each group of signs, the third uses the method of cluster-hierarchical approach to forming integral indicator of assessment of deviant behavior of minors. The indicator has a considerable flexibility of the correlation between groups of symptoms and partial characteristics through the introduction of appropriate sets of weighting coefficients. The conclusion is made about the preference of methods based on clustering of objects in the two-dimensional space of targets or accounts of the principal components method, as well as the need for additional analysis of the graphical picture of the relative location of objects. From the comparison of different approaches: 1) clustering on the basis of the generalized indicator of quality and the sign of reverse deviance, 2) clustering on two accounts of the principal components method; 3) clustering on all signs of examination, the following conclusions can be drawn. All methods properly allocate the objects to clusters. However, when you save the main totals (highlighting the best and worst features), the results are slightly different. This is due to the different volume and forms of presentation of the source information. The program assigns numbers of active neurons (clusters) arbitrarily, so in order to arrange the cluster numbers by some feature (for example, the quality of objects), you need to use additional graphical information. From a practical point of view, the first two methods are preferred, based on clustering objects in two-dimensional space, the method of principal components and the analysis of the graphical picture of the mutual location of objects.

Ig-Like Transcript 2 (ILT2) Blockade and Lenalidomide Restore NK Cell Function in Chronic Lymphocytic Leukemia

One of the cardinal features of chronic lymphocytic leukemia (CLL) is its association with a profound immunosuppression. NK cell function is markedly impaired in CLL patients, who show a significant dysregulation of the expression of activating and inhibitory receptors. Here, we analyzed the role of the novel inhibitory receptor Ig-like transcript 2 (ILT2, also termed LIR-1, LILRB1) in the regulation of NK cells in CLL. Our results show that ILT2 expression was significantly decreased on leukemic cells and increased on NK cells of CLL patients, particularly in those with advanced disease and with bad prognostic features, such as those carrying chromosome del(11q). The immunomodulatory drug lenalidomide may regulate the expression of ILT2 and its ligands in CLL since it significantly increased the expression of ILT2 and partially reestablished the expression of its ligands on leukemic cells. Furthermore, lenalidomide significantly increased the activation and proliferation of NK cells, which was strongly enhanced by ILT2 blockade. Combining ILT2 blockade and lenalidomide activated NK cell cytotoxicity resulting in increased elimination of leukemic cells from CLL patients. Overall, we describe herein the role of an inhibitory receptor involved in the suppression of NK cell activity in CLL, which is restored by ILT2 blockade in combination with lenalidomide, suggesting that it may be an interesting therapeutic strategy to be explored in this disease.

On the values of unipotent characters in bad characteristic

Let G(q) be a Chevalley group over a finite field \mathbb F_q . By Lusztig’s and Shoji’s work, the problem of computing the values of the unipotent characters of G(q) is solved, in principle, by the theory of character sheaves; one issue in this solution is the determination of certain scalars relating two types of class functions on G(q) . We show that this issue can be reduced to the case where q is a prime, which opens the way to use computer algebra methods. Here, and in a sequel to this article, we use this approach to solve a number of cases in groups of exceptional type which seemed hitherto out of reach.

How do parents and providers trade-off between disability and survival? Preferences in the treatment of pediatric medulloblastoma

ObjectiveThe aim of this study was to determine the preferences of parents with children with medulloblastoma and clinicians who manage this condition and their trade-offs between survival and disability using a best–worst scaling (BWS) choice experiment.MethodsMixed methods were used to develop a BWS tool. Health professionals involved in the care of medulloblastoma patients were contacted through oncology networks in Canada. Parents of children diagnosed with brain tumors were recruited via two clinics in Vancouver and Toronto. The profile case BWS was used with each participant completing 12 choice profiles with the respondent indicating the best and worst features of each profile. Surveys were stratified into good, moderate, and poor prognosis based on the probability of survival presented. Paired model conditional logit analysis was used to generate quantitative preferences.ResultsFifty-four parents (80% female) and 176 providers (36% female, 79% oncologists) participated in this study. There were many similarities in the parents’ and providers’ preferences for treatment although the parents tended to value survival higher than disability while providers seemed to value the opposite. Specifically, providers were willing to take more risk of recurrence in a child with good prognosis compared to intermediate and poor prognosis. Also, parents were less willing to take more survival risks than providers when they had to trade-off between mild disability and survival rate.ConclusionThis study provides useful insights into the preferences of parents and health care providers, the stakeholders of a collaborative decision for the treatment of pediatric medullo-blastoma, and compares their values and trade-offs between different levels of survival and disability.

Correntropy-based robust multilayer extreme learning machines

In extreme learning machines (ELM), the hidden node parameters are randomly generated and the output weights can be analytically computed. To overcome the bad feature extraction ability of the shallow architecture of ELM, the hierarchical ELM has been extensively studied as a deep architecture with multilayer neural network. However, the commonly used mean square error (MSE) criterion is very sensitive to outliers and impulsive noises, generally existing in real world data. In this paper, we investigate the correntropy to improve the robustness of the multilayer ELM and provide sparser representation. The correntropy, as a nonlinear measure of similarity, is robust to outliers and can approximate different norms (from ℓ0 to ℓ2). A new full correntropy based multilayer extreme learning machine (FC-MELM) algorithm is proposed to handle the classification of datasets which are corrupted by impulsive noises or outliers. The contributions of this paper are three-folds: (1) The MSE based reconstruction loss is replaced by the correntropy based loss function; In this way, the robustness of the ELM based multilayer algorithms is enhanced. (2) The traditional ℓ1-based sparsity penalty term is also replaced by a correntropy-based sparsity penalty term, which can further improve the performance of the proposed algorithm with a sparser representation of the data. The combination of (1) and (2) provides the correntropy-based ELM autoencoder. (3) The FC-MELM is proposed by using the correntropy-based ELM autoencoder as a building block. It is notable that the FC-MELM is trained in a forward manner, which means fine-tuning procedure is not required. Thus, the FC-MELM has great advantage in learning efficiently when compared with traditional deep learning algorithms. The good property of the proposed algorithm is confirmed by the experiments on well-known benchmark datasets, including the MNIST datasets, the NYU Object Recognition Benchmark dataset, and the Moore network traffic dataset. Finally, the proposed FC-MELM algorithm is applied to address Computer Aided Cancer Diagnosis. Experiments conducted on the well-known Wisconsin Breast Cancer Data (Diagnostic) dataset are presented and show that the proposed FC-MELM outperforms state-of-the-art methods in solving computer aided cancer diagnosis problems.

The effect of mixing method on capillary moisture content of concretes with recycled concrete aggregates

Recycled concrete aggregate represents a major environmental burden in the affected area and its use as an aggregate in concrete production is widespread in many countries. However, such aggregates have worse characteristics and strength than those of natural aggregate. In particular they have a higher absorption rate than natural aggregates, need much more water for mixing, and cause a high slump loss rate depending on the elapsed time. In this context, it is possible to monitor globally extensive research aimed on the elimination of improper properties of alternative aggregates, which are an obstacle to their application in concrete. The sorptivity expressed by capillary moisture content is a characteristic of moisture transport into the material, and recently it has been recognized as an important performance characteristic of durability. The paper is focused on the specific approach to concrete mixing as a way of the improvement of recycled aggregate´s surface using 3 variations of powders as coating materials and 2 kinds of aggregate. The changes in the capillary moisture content are compared and discussed. It is clear that the kind of coating material can influence this performance parameter significantly, so the careful design of mixing process together with the selection of powdery materials is essential. The triple mixing method was found to be promising for recycled concrete aggregate concrete, when fly ash or recycled concrete powder are used in the first stage of mixing. It is a favourable result, taking into account the perspective of the application of secondary raw materials for concrete production.

Graded Caste Inequality and Poverty: Evidence on Role of Economic Discrimination

Graded caste inequality is the most stubborn feature of the ancient caste system which continues with some of its worst features even today. In view of this context, this paper looks at the persistence of graded caste inequality and the role of economic discrimination, drawing mainly from the recent empirical and theoretical research. It examines the following three interrelated aspects of the graded caste inequality (a) Nature of (graded) inequality in income and poverty, and other indicators of human development like malnutrition and education, particularly among three castes: former untouchables (SCs), OBC and higher castes (HCs); (b) Empirical evidence from recent studies on market and non-market discrimination faced by the SC; and (c) Impact of discrimination on income and poverty of SCs, OBCs and HCs in a graded manner. We find that much of the inequality in per capita consumption expenditure is due to inequality in asset ownership (agricultural land and enterprise) and higher education. Most of the explained difference is due to higher education/regular salaried jobs and asset ownership in the form of land and enterprises. In the urban salaried labour market, the contribution of discrimination to wage differential between SCs and HCs is 28.5 per cent in the regular labour market, 19.4 and 31.7 per cent for public and private sectors, respectively. We also find that in the regular labour market, the extent of caste-based wage gap as well as discrimination varies significantly across the quintiles of the wage distribution. The wage gap between SCs and HCs that is attributable to discrimination is higher in top quintiles than at bottom quintiles of wage distribution. We also find that discrimination against SCs and OBCs partially operates through occupational segregation.

Problemi istraživanja self-koncepta, posebice self-koncepta mladih

The results of the previous researches of the self-concept were often controversial creating so some difficulties for comparison and verification. The resource of these deficiencies was in the definition of ithe self-concept which was imprecise and unlike and also in bad metric characteristics of the instruments involved in the research. After well-known researches like Wylie (1974 and 1979) the new researches, encouraged by those, were divided lin 3 groups. In the first group authors examined the metric characteristics of the well-known and long used scales and they also constructed new scales serving for the measurement of self-concept. Those examinations showed the untenableness of some aspects concerning the uni-dimension of the self-concept. The second group examined the theoretical consistency of the self-concept and its relations to the related psychological constructs. The third group worked on the self-concept of youth which was different from the previous and it also and the cross-cultural differences. These studies supported a comprehension of th eself-concept of youth which was different from tile previous and it also supported an idea of a construct being examined within his own culture and also with the instruments available in that culture.

Court of Blood: Treason and Terror under Paraguay's Francisco Solano López

Treason during wartime inspires some of the worst features in the human character. Not only does the traitor besmirch his own reputation in the eyes of his countrymen, but those near him are frequently polluted by association. Worst of all, the desire for vengeance that is unleashed through treasonous acts frequently brings excesses that dwarf the original crime. It is for this reason that magistrates and systems of law in Western democracies have traditionally tried to leech the passion out of individual cases of treason as they attempt to render equitable and just decisions.

Exploiting global and local features for image retrieval

Two lines of image representation based on multiple features fusion demonstrate excellent performance in image retrieval. However, there are some problems in both of them: 1) the methods defining directly texture in color space put more emphasis on color than texture feature; 2) the methods extract several features respectively and combine them into a vector, in which bad features may lead to worse performance after combining directly good and bad features. To address the problems above, a novel hybrid framework for color image retrieval through combination of local and global features achieves higher retrieval precision. The bag-of-visual words (BoW) models and color intensity-based local difference patterns (CILDP) are exploited to capture local and global features of an image. The proposed fusion framework combines the ranking results of BoW and CILDP through graph-based density method. The performance of our proposed framework in terms of average precision on Corel-1K database is 86.26%, and it improves the average precision by approximately 6.68% and 12.53% over CILDP and BoW, respectively. Extensive experiments on different databases demonstrate the effectiveness of the proposed framework for image retrieval.

Mutant allele-specific imbalance in patients with metastatic colorectal cancer.

706 Background: Patients with colorectal cancer(CRC) harboring RAS mutations do not respond to antiepidermal growth factor receptor (anti-EGFR) therapy. Next generation sequencing (NGS) identifies and quantifies mutant and wild type alleles as seen on the sequencing electropherograms. RAS mutant allele-specific imbalance (MASI) occurs when the mutant allele peak is higher than the wild type one. The aims of this study were to verify the rate and tissue distribution of RAS MASI as well as its clinical relevance. Methods: Results of NGS study of patients with metastatic colorectal cancer were collected retrospectively. The clinical charts of patients with RAS mutations were reviewed by the investigators who were blinded to the MASI results. Results: Between August 2014 and Jan 2016, 26 out of 52 (50%)patients tested, were found to harbor RAS mutations. Among them, 11 patients were detected with KRAS MASI(42.3%) Table 1 shows the different characteristics. 6 out of 11 patients presented with synchronous metastatic disease. This correlated with a statistically significant difference in the mean disease free survival that was 9 months in the KRAS MASI group compared with 27.5 months in the non MASI group. A few patients had more than one mutation. ie KRAS Ex2- G12D, 62.3%, PKI3CA Ex9-E545K, 24.6%, Ex20-H1047Y, 0.6% in the MASI group and KRAS Ex2-G12C+G12V - 10.85%, KRAS Ex4-A146T - 10.3%, NRAS gene Ex2-G12D - 1.1%, in non MASI group. Patients in the MASI group had a different clinical profile. (See Table 1) The overall survival of patients was calculated from diagnosis of metastatic disease, till death, 24 months-this was not significantly nor statistically different amongst groups. Conclusions: With the caveat of a small study and a retrospective analysis we showed that patients with MASI have worse characteristics that were translated to a significant shorter disease free survival. OS was not different amongst the groups. [Table: see text]

Two Tales of Lincoln and the Meaning of Democracy

Two Tales of Lincoln and the Meaning of Democracy Erik J. Chaput (bio) Elizabeth Brown Pryor. Six Encounters with Lincoln: A President Confronts Democracy and Its Demons. New York: Viking, 2017. 496 pp. Bibliography and Index. $35.00. Allen C. Guelzo. Redeeming the Great Emancipator. Cambridge, MA: Harvard University Press, 2016. 208 pp. Index. $22.95. Though it was clear that Abraham Lincoln continued to struggle to define exactly what emancipation would mean for the slave, in his December 1862 annual message the president informed Congress that the civil war that had already claimed the lives of thousands of men was being fought to ensure that the American democratic experiment would endure. According to Lincoln, the United States was "the last best, hope of earth" for democracy. As historian Sean Wilentz has noted, "given the blows dealt to democratic governments in the Old World, it was easy enough for Lincoln and others to see America as a singular and even providential nation."1 The protection and promotion of a government by and for the people was as important to Lincoln as saving the Union and ending slavery. However, unlike John Adams or James Madison, Abraham Lincoln never put forth a detailed blueprint for how the tenets of democracy and republican government were to be structured. He was not an original policy thinker in that regard. He simply but forcibly maintained that slavery and democracy were incompatible, and the "fiery trial" of the war would eventually lead to a polity in which all men would be equal to one another. His job, as he had noted in the secession winter, was to protect the words "fitly spoken" in Jefferson's Declaration. Historians of the Civil War era, including James McPherson, James Oakes, Sean Wilentz, and Edward Ayers, generally give Lincoln high marks for his steadfast commitment to preserving a conception of democracy predicated on human equality. Elizabeth Brown Pryor, however, believes that historians need to adopt a more balanced and holistic approach to the study of the Lincoln presidency and how "Lincoln's republic was a government of, by, and for only some of the people" (p. 3). Pryor portrays a president whose vision [End Page 65] of democracy was limited and who repeatedly missed opportunities to aid not only the cause of freedom for black Americans, but also for women and Native Americans. Pryor, who was tragically killed just before her latest book went to press, is not afraid to attack the hallowed image of the sixteenth president. Lincoln's "saving grace is that he upheld a system that allowed for change even when he was not its champion" (p. 9). Overall, Six Encounters with Lincoln is one of the harshest assessments of the Great Emancipator to appear in recent years. "What we must question," the author writes "is whether in doing his best, he did the best for the country" (p. 8). Pryor, a prodigious researcher who examined hundreds of manuscript collections, paints a portrait of an embattled president, unsure of how to handle the pressures of office. Indeed, Pryor's harangue of Lincoln resembles a characterization Reverdy Johnson sketched for George McClellan at the height of the 1864 presidential campaign: His infirmity of purpose, his unsteadiness in any policy, his once expressed dislike to radicalism, his subsequent adoption of its worst features, his ignorant and mischievous interference with our military campaigns, his appointments, often against the advice of high military officers, of notorious incompetency—his frequent and nearly fatal changes of commanders.2 Pryor reconstructs six meetings Lincoln had during his presidency with figures who, while well known in some historical circles, are often not part of either biographical accounts or general narratives of the Civil War era. The author uses the "six encounters" with Lincoln in the White House in order to discuss the contours of American democracy, including civilian control of the military, civil liberties, the politics of emancipation, the fate of Native Americans, the role of women in the war, and the politics of reconstruction. Pryor curiously fails, however, early in the narrative to offer up an account of the ways in which Lincoln understood and used the word "democracy" in his political career, a...

Commutativity in the Algorithmic Lovász Local Lemma

We consider the recent formulation of the algorithmic Lovász Local Lemma [N. Harvey and J. Vondrák, in Proceedings of FOCS, 2015, pp. 1327--1345; D. Achlioptas and F. Iliopoulos, in Proceedings of SODA, 2016, pp. 2024--2038; D. Achlioptas, F. Iliopoulos, and V. Kolmogorov, A Local Lemma for Focused Stochastic Algorithms, arXiv preprint, 2018] for finding objects that avoid “bad features,” or “flaws.” It extends the Moser--Tardos resampling algorithm [R. A. Moser and G. Tardos, J. ACM, 57 (2010), 11] to more general discrete spaces. At each step the method picks a flaw present in the current state and goes to a new state according to some prespecified probability distribution (which depends on the current state and the selected flaw). However, the recent formulation is less flexible than the Moser--Tardos method since it requires a specific flaw selection rule, whereas the algorithm of Moser and Tardos allows an arbitrary rule (and thus can potentially be implemented more efficiently). We formulate a new “commutativity” condition and prove that it is sufficient for an arbitrary rule to work. It also enables an efficient parallelization under an additional assumption. We then show that existing resampling oracles for perfect matchings and permutations do satisfy this condition.

Dynamic Video Stitching via Shakiness Removing.

Stitching videos captured by hand-held mobile cameras can essentially enhance entertainment experience of ordinary users. However, such videos usually contain heavy shakiness and large parallax, which are challenging to stitch. In this paper, we propose a novel approach of video stitching and stabilization for videos captured by mobile devices. The main component of our method is a unified video stitching and stabilization optimization that computes stitching and stabilization simultaneously rather than does each one individually. In this way, we can obtain the best stitching and stabilization results relative to each other without any bias to one of them. To make the optimization robust, we propose a method to identify background of input videos, and also common background of them. This allows us to apply our optimization on background regions only, which is the key to handle large parallax problem. Since stitching relies on feature matches between input videos, and there inevitably exist false matches, we thus propose a method to distinguish between right and false matches, and encapsulate the false match elimination scheme and our optimization into a loop, to prevent the optimization from being affected by bad feature matches. We test the proposed approach on videos that are causally captured by smartphones when walking along busy streets, and use stitching and stability scores to evaluate the produced panoramic videos quantitatively. Experiments on a diverse of examples show that our results are much better than (challenging cases) or at least on par with (simple cases) the results of previous approaches.Stitching videos captured by hand-held mobile cameras can essentially enhance entertainment experience of ordinary users. However, such videos usually contain heavy shakiness and large parallax, which are challenging to stitch. In this paper, we propose a novel approach of video stitching and stabilization for videos captured by mobile devices. The main component of our method is a unified video stitching and stabilization optimization that computes stitching and stabilization simultaneously rather than does each one individually. In this way, we can obtain the best stitching and stabilization results relative to each other without any bias to one of them. To make the optimization robust, we propose a method to identify background of input videos, and also common background of them. This allows us to apply our optimization on background regions only, which is the key to handle large parallax problem. Since stitching relies on feature matches between input videos, and there inevitably exist false matches, we thus propose a method to distinguish between right and false matches, and encapsulate the false match elimination scheme and our optimization into a loop, to prevent the optimization from being affected by bad feature matches. We test the proposed approach on videos that are causally captured by smartphones when walking along busy streets, and use stitching and stability scores to evaluate the produced panoramic videos quantitatively. Experiments on a diverse of examples show that our results are much better than (challenging cases) or at least on par with (simple cases) the results of previous approaches.

A New Approach of Rough Set Theory for ‎Feature Selection and Bayes Net Classifier ‎Applied on Heart Disease Dataset

In this paper a new approach of rough set features selection has been proposed. Feature selection has been used for several reasons a) decrease time of prediction b) feature possibly is not found c) present of feature case bad prediction. Rough set has been used to select most significant features. The proposed rough set has been applied on heart diseases data sets. The main problem is how to predict patient has heart disease or not depend on given features. The problem is challenge, because it cannot determine decision directly .Rough set has been modified to get attributes for prediction by ignored unnecessary and bad features. Bayes net has been used for classified method. 10-fold cross validation is used for evaluation. The Correct Classified Instances were 82.17, 83.49, and 74.58 when use full, 12, 7 length of attributes respectively. Traditional rough set has been applied, the minimum Correct Classified Instances were 58.41 and 81.51 when use 2 length of attributes respectively

Simultaneous ranking and selection of keystroke dynamics features through a novel multi-objective binary bat algorithm

In this paper, we propose a novel multi-objective binary bat algorithm for simultaneous ranking and selection of keystroke dynamics features. The proposed algorithm uses the V shaped binarization function. Simulation results show that, the proposed algorithm can efficiently identify the most important features of the data set. Of the three feature classes, the key down hold time features (H-features) are proofed to be the most dominant features. Using H-features only in classification decreases the mean square error (MSE) by 2% compared to choosing all features in classification. The UD features are the second ranked features. The worst features are the DD features which represent the largest MSE when being used individually in the classification process. The results are performed using two classifiers for comparisons; the linear and the quadratic classifiers. The quadratic classifier outperforms the linear classifier with respect to the mean square error (MSE) and the average number of features selected.

Internal rate of return: Good and bad features, and a new way of interpreting the historic measure

IRR, a widely used profitability measure, is the Discount Rate that yields Net Present Value (NPV)=0 for a stream of positive and negative cash flows, at least one of each sign and with no explicit financing payments. A big disadvantage is lack of parameters, such as a project finance rate or the enterprise rate (ER), i.e., Return on Investment of the overarching investment group to serve as a measure of opportunity cost. The coupled metrics proposed earlier by the author— NPVproject and NPV%–do not suffer these disadvantages, so IRR is analyzed in terms of NPV%. Useful information can be obtained from a projection of IRR values onto the NPV%, ER plane revealing the sensitivity of IRR to risk under meaningful operating conditions.

My worst faults and misdeeds: Self-criticism and self-enhancement can co-exist

Three studies explored whether self-enhancement is precluded when people recognize or even exaggerate their worst faults and behaviors. Even when acknowledging their faults, participants minimized the extent to which their bad characteristics reflected what kind of people they were, predicted that they would improve more in the future than would others with the same faults, claimed that others have done worse things to them than they have to others, and indicated that others are more likely to repeat the same bad behaviors in the future than themselves. Observers who read actors’ descriptions of their own misdeeds and those of others also saw the things that were done to actors as worse than the things actors had done.

Association between socioeconomic and physical/built neighborhoods and disability: A systematic review

The aim of this systematic review was to assess the association between the characteristics of the socioeconomic and physical/built neighborhoods and disability in basic activities of daily living (ADL) and/or instrumental activities of daily living (IADL). Six databases were searched. Fourteen from the 1811 identified studies were included. Neighborhoods with socioeconomic disadvantage were associated with ADL/IADL disabilities in 7 out of the 11 studies with this objective. Worst features of the physical/built neighborhoods were associated with disabilities in only 3 of the 7 studies that investigated this. Relative to the physical/built, the socioeconomic neighborhood and ADL/IADL disabilities were more consistently associated in the still scarcely available literature on the subject.

Posttraumatic stiff elbow

Posttraumatic stiff elbow is a frequent and disabling complication and poses serious challenges for its management. In this review forty studies were included to know about the magnitude of the problem, causes, pathology, prevention, and treatment of posttraumatic stiff elbow. These studies show that simple measures such as internal fixation, immobilization in extension, and early motion of elbow joint are the most important steps that can prevent elbow stiffness. It also supports conservative treatment in selected cases. There are no clear guidelines about the choice between the numerous procedures described in literature. However, this review article disproves two major beliefs-heterotopic ossification is a bad prognostic feature, and passive mobilization of elbow causes elbow stiffness.