SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Subroutine

171

We introduce a new method for detecting communities of arbitrary size in an undirected weighted network. Our approach is based on tracing the path of closest-friendship between nodes in the network using the recently proposed Generalized Erds Numbers. This method does not require the choice of any arbitrary parameters or null models, and does not suffer from a system-size resolution limit. Our closest-friend community detection is able to accurately reconstruct the true network structure for a large number of real world and artificial benchmarks, and can be adapted to study the multi-level structure of hierarchical communities as well. We also use the closeness between nodes to develop a degree of robustness for each node, which can assess how robustly that node is assigned to its community. To test the efficacy of these methods, we deploy them on a variety of well known benchmarks, a hierarchal structured artificial benchmark with a known community and robustness structure, as well as real-world networks of coauthorships between the faculty at a major university and the network of citations of articles published in Physical Review. In all cases, microcommunities, hierarchy of the communities, and variable node robustness are all observed, providing insights into the structure of the network.

Concepts: Scientific method, Structure, Hierarchy, Graph theory, Academic degree, Networks, Subroutine, Social network

156

Model-based analysis of fMRI data is an important tool for investigating the computational role of different brain regions. With this method, theoretical models of behavior can be leveraged to find the brain structures underlying variables from specific algorithms, such as prediction errors in reinforcement learning. One potential weakness with this approach is that models often have free parameters and thus the results of the analysis may depend on how these free parameters are set. In this work we asked whether this hypothetical weakness is a problem in practice. We first developed general closed-form expressions for the relationship between results of fMRI analyses using different regressors, e.g., one corresponding to the true process underlying the measured data and one a model-derived approximation of the true generative regressor. Then, as a specific test case, we examined the sensitivity of model-based fMRI to the learning rate parameter in reinforcement learning, both in theory and in two previously-published datasets. We found that even gross errors in the learning rate lead to only minute changes in the neural results. Our findings thus suggest that precise model fitting is not always necessary for model-based fMRI. They also highlight the difficulty in using fMRI data for arbitrating between different models or model parameters. While these specific results pertain only to the effect of learning rate in simple reinforcement learning models, we provide a template for testing for effects of different parameters in other models.

Concepts: Scientific method, Psychology, Brain, Human brain, Machine learning, Theory, Subroutine, C++

28

Acousticians and other practitioners alike often describe acoustic conditions in performance spaces with standard objective parameters. Apart from a few exceptions, the parameters are calculated by integrating the sound energy of the impulse responses over time; this makes them inadequate for researching the acoustics in detail, especially in the early part of the room impulse response. This paper proposes a method based on time-frequency and spatiotemporal presentations to overcome the lack of detail in the standard analysis. In brief, the proposed methods visualize the cumulative development of the sound field as a function of frequency or direction by forward-integrating the energy in the impulse response in short time frames. Analysis on the measurements from six concert halls concentrates particularly on interpreting the results in light of the seat dip effect. Earlier research has concluded that the seat dip effect is reduced by reflection from low overhead surfaces. In contrast, the current results indicate that the seat dip attenuation in the frequency response is corrected the best when the hall provides most lateral reflections. These findings suggest that the proposed analysis is suitable for explaining concert hall acoustics in detail.

Concepts: Light, Acoustics, Sound, Subroutine, LTI system theory, Frequency response, Maximum length sequence, Impulse response

28

The objective of this study was to compare some husbandry procedures on the base of physiological stress parameters and evaluate the welfare status in sheep. Forty ewes were used as the study material. Measurements were taken during several routine husbandry procedures such as milking, shearing, weighing, loading and hoof care. Data regarding time spent for each application, as well as heart and respiratory rates were recorded during the applications. Blood samples were taken 15 min before and after each application and malondialdehyde (MDA), glutathione-peroxidase (GSH-Px), cortisol T3 and T4 parameters were measured. In addition, changes in the same parameters between pre- and post-application periods were evaluated. According to the results, machine milking caused less stress than hand milking. No significant difference was seen between shearing methods for hand shearer or clipper; however, both applications caused stress in animals. The results for weighing methods of animals demonstrated significant differences in cortisol, T3 and T4 values in favor of traditional method. Cortisol, T3 and T4 levels were significantly higher in manual loading compared with loading by ramp. Regarding hoof care, all the examined parameters differed in favor of modern method. On the other hand, significant differences were determined between the stress parameters regarding pre- and post-applications. All values differed for hand milking while no significant difference was observed in MDA and T3 values in machine milking group. Parameters in weighing groups changed significantly. For loading process, GSH, cortisol, T3 and T4 values differed in both treatment groups. With regard to hoof care, parameters except T4 in laying group differed significantly. An increase occurred in minute-based measurements of heart and respiratory rates parallel to physiological data. The number of the respiratory rates during the applications differed except for the shearing process. All the parameters displayed significant differences between groups in terms of heart rates. Time spent for each application also differed between groups. Time saved for milking, shearing, weighing, loading and hoof care was 3.23 min, 4.37 min, 1.71 min, 7.85 s and 1.55 min, respectively. These results appear to provide a tangible advantage of using new husbandry methods to the breeders. It was concluded that using new methods in sheep husbandry procedures provided advantages in terms of saving time and reducing labor, as well as improved conditions for welfare of animals. In addition, it facilitated the routine works and flock husbandry.

Concepts: Physiology, Statistical significance, Metabolic syndrome, Stress, Livestock, Subroutine, Domestic sheep, Sheep husbandry

28

PURPOSE. To understand the medication routines used by older adults taking four or more medications daily. METHOD. One hundred forty-nine community-dwelling older adults were interviewed about the individual routines, storage locations, equipment, and assistance that enabled their adherence to a medication regimen. A subsample of 84 older adults was observed completing one medication routine in their home environments. FINDINGS. Medication habits were embedded in mealtime, wake-up, and sleep routines for 91% of the sample. Participants developed unique, individualized behaviors for taking medications that were choreographed within broader daily routines. The primary locations for storing medications were the kitchen and bathroom. Equipment used to promote adherence was primarily pillboxes or self-made adaptations. More than 50% of the entire sample required some type of assistance related to medication adherence. IMPLICATIONS. Findings support the role of occupational therapists in collaborating with clients to develop individualized medication routines to promote medication adherence.

Concepts: Pharmacology, Prescription drug, Medicine, Sampling, Pharmaceutical drug, Subroutine, Occupational therapy

27

Controlled attenuation parameter (CAP) evaluated with transient elastography (FibroScan) is a recent method for non invasive assessment of steatosis. Its usefulness in clinical practice is unknown. We prospectively investigated the determinants of CAP failure and the relationships between CAP and clinical or biological parameters in a large cohort of consecutive patients.

Concepts: Epidemiology, Clinical trial, Pathology, Ecology, Parameter, Subroutine

27

In this paper, we propose an object-aware Holistic superPixel Selection (HPS) method to automatically select the discriminative superpixels of an image for image classification purpose. Through only considering the selected superpixels, the interference of cluttered background on the object can be alleviated effectively and thus the classification performance is significantly enhanced. In particular, for an image, HPS first selects the discriminative superpixels for the characteristics of certain class, which can together match the object “template” of this class well. And then these superpixels compose a classspecific matching region. By performing such superpixel selection for several most probable classes respectively, HPS generates multiple class-specific matching regions for a single image. Then HPS merges these matching regions into an integral object region through exploiting their pixel-level intersection information. Finally such object region instead of the original image is used for image classification. An appealing advantage of HPS is the ability to alleviate the interference of cluttered background yet not require the object to be segmented out accurately. We evaluate the proposed HPS on four challenging image classification benchmark datasets: Oxford-IIIT PET 37, Caltech-UCSD Birds 200, Caltech 101, and PASCAL VOC 2011. The experimental results consistently show that the proposed HPS can remarkably improve the classification performance.

Concepts: Java, Object-oriented programming, Proposal, Selection, Subroutine, Region, C++, C Sharp

27

The purpose of the study was to explore patterns of parent involvement as perceived by teachers and identify correlates of these patterns. Parent involvement indicators and correlates were selected from a review of existing research. Participants included 34 teachers and 577 children in kindergarten through third grade. The vast majority of the sample was African American (78%), followed by Caucasian (19%) and other ethnic backgrounds (2%). Two subscales from the Parent Involvement-Teacher scale, contact and comfort, were entered as indicators in a latent profile analysis to determine the number and types of parent involvement classes. Contact included the frequency of interactions between parents and teachers; comfort included the quality of their relationship with the parent and how well their goals were aligned. Subsequent latent class regressions were conducted to identify student, school, and family characteristics associated with class membership. Three classes provided the optimal solution. This included two classes of parents with low contact with teachers but different comfort levels; one with low contact and low comfort (11%), and one with low contact but high comfort (71%). The remaining class, representing 18% of parents, was rated high on both contact and comfort. Low income status, family problems, and social, emotional, academic, and self-regulation problems distinguished the low comfort class from the other two classes. It is imperative to help teachers feel more comfortable working with families who may be experiencing substantial stressors and who also have children who need support across school and home settings. (PsycINFO Database Record © 2013 APA, all rights reserved).

Concepts: Family, Java, Ethnic group, Mother, All rights reserved, Subroutine, Ruby, Python

27

A structural investigation is reported of polymorphs of Ga(2) O(3) that, despite much interest in their properties, have hitherto remained uncharacterised due to structural disorder. The most crystalline sample yet reported of γ-Ga(2) O(3) was prepared by solvothermal oxidation of gallium metal in ethanolamine. Structure refinement using the Rietveld method reveals γ-Ga(2) O(3) has a defect Fd3¯m spinel structure, while pair distribution function analysis shows that the short-range structure is better modelled with local F4¯3m symmetry. In further solvothermal oxidation reactions a novel gallium oxyhydroxide, Ga(5) O(7) (OH), is formed, the thermal decomposition of which reveals a new, transient gallium oxide polymorph, κ-Ga(2) O(3) , before transformation into β-Ga(2) O(3.) In contrast, the thermal decomposition of Ga(NO(3) )(3) ⋅9 H(2) O first forms ε-Ga(2) O(3) and then β-Ga(2) O(3) . Examination of in situ thermodiffraction data shows that ε-Ga(2) O(3) is always contaminated with β-Ga(2) O(3) and with this knowledge a model for its structure was deduced and refined-space group P6(3) mc with a ratio of tetrahedral/octahedral gallium of 2.2:1 in close-packed oxide layers. Importantly, thermodiffraction provides no evidence for the existence of the speculated bixbyite structured δ-Ga(2) O(3) ; at the early stages of thermal decomposition of Ga(NO(3) )(3) ⋅9 H(2) O the first distinct phase formed is merely small particles of ε-Ga(2) O(3) .

Concepts: Diffraction, Crystallography, Structure, Nitrogen, Aluminium, Subroutine, Gallium, Rietveld refinement

26

Skin absorption testing in vitro is a regulatory accepted alternative method (OECD Guideline 428). Different tests can be applied to evaluate the integrity of the skin samples. Here, we compared the pre- or post-run integrity tests (transepidermal electrical resistance, TEER; transepidermal water loss, TEWL; absorption of the reference compounds water, TWF, or methylene blue, BLUE) and additionally focused on co-absorption of a (3)H-labeled internal reference standard (ISTD) as integrity parameter. The results were correlated to absorption profiles of various test compounds. Limit values of 2kΩ, 10gm(-2)h(-1) and 4.5∗10(-3) cmh(-1) for the standard methods TEER, TEWL and TWF, respectively, allowed distinguishing between impaired and intact human skin samples in general. Single skin samples did, however, not, poorly and even inversely correlate with the test-compound absorption. In contrast, results with ISTD (e.g. (3)H-testosterone) were highly correlated to the absorption of (14)C-labeled test compounds. Importantly, ISTD did not influence analytics or absorption of test compounds. Therefore, ISTD, especially when adjusted to the physico-chemical properties of test compounds, is a promising concept to assess the integrity of skin samples during the whole course of absorption experiments. However, a historical control dataset is yet necessary for a potential routine application.

Concepts: Statistics, Skin, In vitro, Correlation and dependence, Value, Subroutine, Electrical resistance