Statistical Mechanics and Kinetics of Amyloid Fibrillation

Amyloid fibrillation is a protein self-assembly phenomenon that is intimately related to well-known human neurodegenerative diseases. During the past few decades, striking advances have been achieved in our understanding of the physical origin of this phenomenon and they constitute the contents of this review. Starting from a minimal model of amyloid fibrils, we explore systematically the equilibrium and kinetic aspects of amyloid fibrillation in both dilute and semi-dilute limits. We then incorporate further molecular mechanisms into the analyses. We also discuss the mathematical foundation of kinetic modeling based on chemical mass-action equations, the quantitative linkage with experimental measurements, as well as the procedure to perform global fitting.Comment: 68 pages, 18 figures, 201 reference

Learning to Associate Words and Images Using a Large-scale Graph

We develop an approach for unsupervised learning of associations between co-occurring perceptual events using a large graph. We applied this approach to successfully solve the image captcha of China's railroad system. The approach is based on the principle of suspicious coincidence. In this particular problem, a user is presented with a deformed picture of a Chinese phrase and eight low-resolution images. They must quickly select the relevant images in order to purchase their train tickets. This problem presents several challenges: (1) the teaching labels for both the Chinese phrases and the images were not available for supervised learning, (2) no pre-trained deep convolutional neural networks are available for recognizing these Chinese phrases or the presented images, and (3) each captcha must be solved within a few seconds. We collected 2.6 million captchas, with 2.6 million deformed Chinese phrases and over 21 million images. From these data, we constructed an association graph, composed of over 6 million vertices, and linked these vertices based on co-occurrence information and feature similarity between pairs of images. We then trained a deep convolutional neural network to learn a projection of the Chinese phrases onto a 230-dimensional latent space. Using label propagation, we computed the likelihood of each of the eight images conditioned on the latent space projection of the deformed phrase for each captcha. The resulting system solved captchas with 77% accuracy in 2 seconds on average. Our work, in answering this practical challenge, illustrates the power of this class of unsupervised association learning techniques, which may be related to the brain's general strategy for associating language stimuli with visual objects on the principle of suspicious coincidence.Comment: 8 pages, 7 figures, 14th Conference on Computer and Robot Vision 201

Evolution of the Pancaking Effect in a LCDM Cosmology

We explore the evolution of the large-scale anisotropy in the velocity field caused by the gravitational pancaking effect assuming a LCDM universe. The Millennium Run halo catalogs at four different redshifts, z=0, 0.5, 1 and z=2 are analyzed to find that the pancaking effect starts to intervene the hierarchical structure formation at redshift z=2 when a characteristic pancake scale is around 3 Mpc/h. It is also clearly shown how the degree and scale of the pancaking effect changes with time. An analytic model based on the Zel'dovich approximation is presented to explain quantitatively the evolution of the velocity-pancake alignment. A cosmological implication of our finding and a possibility of detecting a signal in real universe are discussed.Comment: accepted by ApJ, 21 pages, 6 figures, discussion and error analysis improve

Accounting for the financialized UK and US national business model

The term ‘business model’ (BM) is generally used to describe the possibilities of transforming corporate activities and business functions (Osterwalder et al,2005 and Magretta,2002) In this paper we argue that our understanding of what constitutes a BM can be reworked to generate a useful organizing framework to investigate the nature of national economic development and transformation. Our argument is that national business models are subtended within a broad econo‐sphere where they evolve and adapt to information arising out of stakeholder interactions. These interactions congeal into reported financial numbers that are represented as GDP flow (income and surplus) and Balance Sheet accumulations (assets and liabilities outstanding). In this paper we employ financial data from national accounts to specifically describe how the US and UK national business models have financialized. We observe that balance sheet capitalization has inflated ahead of earnings and surplus. Our argument is that the capitalization of a national business model is not simply the mathematical product of discounting corporate cash earnings. The process of on‐going capitalization is also conditioned by variable institutional sector characteristics where financial innovation is possible and, within credit based economies, goodwill and holding gains arising out of asset inflation also provide collateral for further ongoing recapitalizations. In financialized national business models the system of accounting takes on added analytical significance because it ‘transmits rather than contains’ and ‘amplifies rather than dampens’ adverse financial disturbance as capitalizations are recalibrated up or down.Peer reviewe

Promoting creative English teaching using Chinese culture for elementary schooling in Taiwan

To make English an interesting subject for elementary school students, teachers need to know what material attracts students, how to motivate students, and how to release students\u27 creativity. Therefore, This project incorporates the concepts of multiple intelligences, motivation, culture and language, and development of creativity to provide a model for promoting creative English teaching in the elementary schools of Taiwan. In addition, the content of the unit, based on Chinese culture and the comparison of Chinese and American cultures, is an innovative curriculum designed to motivate students to learn English

Integrating constructivist approaches in e-learning to enhance mathematical self-study

E-learning models are currently practised widely all over the world due to the rapid growth of distance and global education. Furthermore, e-learning provides high quality educational offerings (Seufert 2002) and allows a convenient and flexible learning environment without restriction of learning space, distance and time (Albrechtsen et al. 2001). Hence, distance education is widely accepted by most of the nontraditional learners (Williams et al. 2002; Leonard & Guha 2001). Open University Malaysia (OUM) is one of the distance education universities in Asia that involves in hybrid concepts for learning. With advance media and communication technologies, OUM is capable of conducting courses using a combination of self-study process (provided with printed learning material), fortnightly face to face tutorials (five tutorials, two hours each per semester) and online communication (between studentsstudents and students-tutors)

Using E-learning to enhance the learning of graph transformations

Graphical representation of functions give more meaning to algebraic expressions and is suited to a particular mathematical task. Most of the distance students in Open University Malaysia (OUM) are unable to graph functions and cannot sufficiently understand graph transformations when taught through printed learning materials. Therefore, e-learning is recommended as an aid to enhance the learning of graph transformations for various types of functions. The objectives of the e-learning are to enable students to: 1) visualize graph transformations, 2) simulate graphical representations and 3) sketch functions with guidance. The e-learning develops in a natural progression from an animated presentation to guided and advanced level exercises. The elements of animation and interactivity create an educationally stimulating environment that can enhance the learning of mathematical issues and discovery of mathematical principles. This e-learning will be tested with the students in OUM to verify its effectiveness in the learning of functions and graph transformations. (Author's abstract

Resource use and foraging activity of Mexican free-tailed bats, Tadarida brasiliensis mexicana (Molossidae)

Foraging patterns and the food habits of insectivorous bats may evolve in response to a variety of intrinsic (e.g., energetic demands, nutrient requirements, and morphological or physiological constraints in acquiring and consuming food) and extrinsic factors (e.g., the distribution and abundance of insect prey, and interactions with other organisms). This study investigates the foraging behavior and ecology of Mexican free-tailed bats, Tadarida brasiliensis mexicana (Saussure, 1860) (Molossidae) residing in large colonies, with emphases on their dietary breadth and variation, their foraging activity, and their resource use patterns. Food habits and dietary variation of insectivorous Mexican free-tailed bats were investigated at three large maternity colonies located in south central Texas. Food habits of bats were determined by analyzing fecal samples collected from individuals. Diets of bats from the two nightly feeding bouts, across seasonal phases, and from bats of different sex, age, and reproductive status were compared. Mexican free-tailed bats fed on a variety of insects, including at least 12 orders and 38 families. The size of coleopterans eaten were mostly from ca. 4 to 9 mm in length. Overall, lepidopterans, coleopterans, and hemipterans were the three most abundant prey in the diet. Homopterans, hymenopterans, and dipterans were less abundant, and other insects, including ephemeropterans, neuropterans, odonatans, orthopterans, plecopterans, and trichopterans were present in small amounts. The diet of bats varied in the relative importance of insect orders in samples collected at midnight versus at dawn, and along seasonal phases. In late May-mid July, coleopterans and hemipterans were in higher proportions in the midnight, but lepidopterans were more abundant at dawn. In mid June-mid July, lepidopterans increased and hemipterans decreased in samples collected at midnight. In late July-August, the proportions of lepidopterans in diets decreased both at midnight and at dawn. The diet also varied among bats of different age, sex, and reproductive status. Pregnant females ate less lepidopterans, but more coleopterans and hemipterans than other adults. Juveniles ate less lepidopterans and neuropterans but higher proportions of coleopterans and homopterans than adults. In addition, reproductive females showed a more diverse diet than males, and juveniles had a more diverse diet than adults. The foraging activity and resource use of Mexican free-tailed bats was investigated in a large maternity colony in Uvalde County, Texas. Foraging activity of bats was studied by recording their echolocation calls at sites along a sampling transect, which represented three different habitats; towns, cropland, and ranches. The proportion of time in which signals were received and the number of feeding buzzes per unit time were quantified. Insect availability and the relative abundance of different insect orders in the three habitats were assessed using light traps. The food habits of the bats were determined from fecal samples, and were compared to the relative abundance in mass of insect orders. Mexican free-tailed bats had a higher foraging activity in town habitats than in cropland and ranches. In cropland and ranch habitats, feeding buzzes per unit time were less frequent in the pre-dawn collecting session than in the evening session, corresponding to the pattern of insect abundance in these habitats. In town habitats, however, insect abundance was similar in morning and evening sessions, and the foraging activity of bats did not differ between these two sessions. The relative importance of the common prey orders both in relative frequency of occurrence and relative volume in the diet of the bats were compatible with the relative importance of these respective insect orders in relative frequency of occurrence and in relative mass in trap collections. Graphic comparisons showed a shift of proportions of different prey in the diet between midnight and dawn, in response to the change of abundance of these insects in light traps. In addition, there was a positive correlation between the diet of bats and the light trap collections at the ordinal level, in 9 of 12 comparisons when Orthoptera was included, and in all 12 comparisons if Orthoptera were removed. The diverse diet and patterns of foraging activity and resource use of Mexican free-tailed bats have implications for insect pest management and conservation. The temporal and seasonal variation of moth consumption in the diet of the bats showed a clear correlation with the availability of large migratory populations of agriculturally injurious moths. The evaluation at the ordinal and family levels, considering the diversity of insect prey of the bats, also suggests that the insect-eating by the bats might be agriculturally beneficial. Together with other lines of evidence, the data suggest that Mexican free-tailed bats have a potentially significant contribution in regulating agricultural insect pests. The decline of Mexican free-tailed bat populations, and their seasonal and patchy distribution, warrant conservation concerns and efforts