Multitraining support vector machine for image retrieval

Relevance feedback (RF) schemes based on support vector machines (SVMs) have been widely used in content-based image retrieval (CBIR). However, the performance of SVM-based RF approaches is often poor when the number of labeled feedback samples is small. This is mainly due to 1) the SVM classifier being unstable for small-size training sets because its optimal hyper plane is too sensitive to the training examples; and 2) the kernel method being ineffective because the feature dimension is much greater than the size of the training samples. In this paper, we develop a new machine learning technique, multitraining SVM (MTSVM), which combines the merits of the cotraining technique and a random sampling method in the feature space. Based on the proposed MTSVM algorithm, the above two problems can be mitigated. Experiments are carried out on a large image set of some 20 000 images, and the preliminary results demonstrate that the developed method consistently improves the performance over conventional SVM-based RFs in terms of precision and standard deviation, which are used to evaluate the effectiveness and robustness of a RF algorithm, respectively

Growth Tight Actions

We introduce and systematically study the concept of a growth tight action. This generalizes growth tightness for word metrics as initiated by Grigorchuk and de la Harpe. Given a finitely generated, non-elementary group $G$ acting on a $G$--space $\mathcal{X}$, we prove that if $G$ contains a strongly contracting element and if $G$ is not too badly distorted in $\mathcal{X}$, then the action of $G$ on $\mathcal{X}$ is a growth tight action. It follows that if $\mathcal{X}$ is a cocompact, relatively hyperbolic $G$--space, then the action of $G$ on $\mathcal{X}$ is a growth tight action. This generalizes all previously known results for growth tightness of cocompact actions: every already known example of a group that admits a growth tight action and has some infinite, infinite index normal subgroups is relatively hyperbolic, and, conversely, relatively hyperbolic groups admit growth tight actions. This also allows us to prove that many CAT(0) groups, including flip-graph-manifold groups and many Right Angled Artin Groups, and snowflake groups admit cocompact, growth tight actions. These provide first examples of non-relatively hyperbolic groups admitting interesting growth tight actions. Our main result applies as well to cusp uniform actions on hyperbolic spaces and to the action of the mapping class group on Teichmueller space with the Teichmueller metric. Towards the proof of our main result, we give equivalent characterizations of strongly contracting elements and produce new examples of group actions with strongly contracting elements.Comment: 29 pages, 4 figures v2 added references v3 40 pages, 6 figures, expanded preliminary sections to make paper more self-contained, other minor improvements v4 updated bibliography, to appear in Pacific Journal of Mathematic

Comparison of Compliance with Cervical Cancer Screening among Women aged 18 and above in Arkansas and the United States

Introduction: Cervical cancer preys on women without access to preventative screening. Any woman who has developed an invasive case of cervical cancer should be regarded as a failure of screening. Disparities in access to screening, triage, and treatment fuel an uneven distribution in the burden of cervical cancer within the United States; weighing unusually heavy on the Southern States like Arkansas. The purpose of this study was to evaluate demographic and behavioral risk factors for cervical cancer and identify potential barriers which may influence the likelihood of complying with current Pap test recommendations on a state level, in Arkansas, and also a national scale, in the United States. Materials and Methods: National data from the 2014 Behavioral Risk Factor Survey System (BRFSS) was used to collect demographic characteristics and behavioral risk factors among females aged 18 and above in Arkansas and the United States. BFRSS data included a total of 1,587 women in Arkansas and 162,222 in the United States who were aged 18 and above and eligible to receive Pap tests. Women with a medical history of hysterectomy that included the removal of the cervix were excluded from analysis because they are not considered to be medically eligible to receive Pap tests. Results: Socioeconomic status, age, race, and health insurance were significantly associated with likelihood to comply with current screening recommendations among women in both Arkansas and the United States. Arkansan women who had less than a 12-year education (Odds Ratio (OR) = 1.41, 95% Confidence Interval (CI) = 1.04, 1.64) and were without health insurance (OR = 3.56, 95% CI = 1.66, 7.66) were more likely to be non-compliant with Pap testing, which is similar to the finding on the national level. The prevalence of Pap test compliance was significantly lower among women in Arkansas when compared to US average in every sociodemographic sector. Discussion: According to US Census data collected in 2013, Arkansas had the highest cervical cancer incidence of 10.6 per 100,000 person-years, while the national average was 7.7 per 100,000 person-years. Therefore, future population-based cervical cancer interventions in Arkansas should target the promotion of Pap test compliance among the most vulnerable subpopulations (i.e., low socioeconomic status, minority, medically under or uninsured). Organized screening interventions might include offering free or reduced cost Pap testing in both urban and rural locations

Stable Heteronuclear Few-Atom Bound States in Mixed Dimensions

We study few-body problems in mixed dimensions with $N \ge 2$ heavy atoms trapped individually in parallel one-dimensional tubes or two-dimensional disks, and a single light atom travels freely in three dimensions. By using the Born-Oppenheimer approximation, we find three- and four-body bound states for a broad region of heavy-light atom scattering length combinations. Specifically, the existence of trimer and tetramer states persist to negative scattering lengths regime, where no two-body bound state is present. These few-body bound states are analogous to the Efimov states in three dimensions, but are stable against three-body recombination due to geometric separation. In addition, we find that the binding energy of the ground trimer and tetramer state reaches its maximum value when the scattering lengths are comparable to the separation between the low-dimensional traps. This resonant behavior is a unique feature for the few-body bound states in mixed dimensions.Comment: Extended version with 14 pages and 14 figure