Modeling Growth Stocks via Size Distribution

The inability to predict the earnings of growth stocks, such as biotechnology and internet stocks, leads to the high volatility of share prices and difficulty in applying the traditional valuation methods. This paper attempts to demonstrate that the high volatility of share prices can nevertheless be used in building a model that leads to a particular size distribution, which can then be applied to price a growth stock relative to its peers. The model focuses on both transient and steady state behavior of the market capitalization of the stock, which in turn is modeled as a birth-death process. In addition, the model gives an explanation to an empirical observation that the market capitalization of internet stocks tends to be a power function of their relative ranks.

Real-time particle dispersion from a DPI using image velocimetry – Evaluation of powder adhesion, impact, and collision

Dry powder inhaler (DPI) is a dosage form for delivering fine drug powders to the respiratory tract. Particle size and size distribution, proportion of fines, particle shape, particle surface roughness, flow rate and adhesion force have been reported to affect the aerosolization process. Several mechanisms for particle dispersion in DPI have been considered; a proposed mechanism to explain the particle dispersion phenomenon is the active site theory. However, there have been several conflicting reports, therefore, an agglomeration/fracture hypothesis has been also proposed. Particle dispersion is associated with events such as impact, acceleration, shear stress, and turbulent flow. The aim of this study is to use high-speed video imaging to provide direct experimental observation of the particle dispersion process in order to unveil a mechanism for particle dispersion. Mixture of micronized lactose and coarse lactose carrier was placed in a model inhaler device, a high speed video imaging was used to capture the dry powder inhalation process. The flow pattern was found to be turbulent. Particles were observed to collide with one another, causing detachment of micronized particles from the surfaces of the coarse lactose particles. Impact of the powder agglomerates on the device grid also contributed to deaggregation and dispersion of the particles. The findings suggest that collision and impact are important mechanisms for the dispersion of DPI particles

Single Molecule Conformational Memory Extraction: P5ab RNA Hairpin

Extracting kinetic models from single molecule data is an important route to mechanistic insight in biophysics, chemistry, and biology. Data collected from force spectroscopy can probe discrete hops of a single molecule between different conformational states. Model extraction from such data is a challenging inverse problem because single molecule data are noisy and rich in structure. Standard modeling methods normally assume (i) a prespecified number of discrete states and (ii) that transitions between states are Markovian. The data set is then fit to this predetermined model to find a handful of rates describing the transitions between states. We show that it is unnecessary to assume either (i) or (ii) and focus our analysis on the zipping/unzipping transitions of an RNA hairpin. The key is in starting with a very broad class of non-Markov models in order to let the data guide us toward the best model from this very broad class. Our method suggests that there exists a folding intermediate for the P5ab RNA hairpin whose zipping/unzipping is monitored by force spectroscopy experiments. This intermediate would not have been resolved if a Markov model had been assumed from the onset. We compare the merits of our method with those of others

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

A Contrastive Study of Curriculum Implementation in English Gifted and Regular Classes:A Case Study of an EFL Teacher in Taiwan

[[abstract]]ABSTRACT This study aimed to investigate a senior high school English teacher’s curriculum implementation in both the second-year English gifted and regular classes in a public school in Taiwan. The focuses of this case study were placed on (a) the differentiation practices in terms of content materials, instructional strategies, and assessment implementation and (b) the factors influencing her decision-making in both classes. The data collection instruments in this qualitative study consisted of two-month classroom observations, semi-structured interviews, and questionnaire survey. Drawing on the comprehensive data, it was found that the target teacher adopted traditional teacher-centered and form-focused instruction, and there were no significant instructional differences between the two classes. Only slightly differentiated curriculum and instruction was discovered. Generally, in terms of content materials, compacted/accelerated, challenging, enriched and deepened materials were more salient in the English gifted class. Regarding instructional strategies, the two classes differed from each other mainly in the teacher’s use of the target language, training of processing skills, use of questioning, and implementation of discussions. As for assessment, the English talented learners were given stricter grading policies for oral presentations. Despite these few differentiations, the in-depth interview data have shown the target teacher’s ample knowledge and competence for providing differentiation for the English talented learners. Basically, in addition to student and administration factors, the target teacher’s controversial belief claiming equal curriculum provision between gifted/talented and regular learners also dictated her differentiation practices. For teacher thinking, the interview data indicated that both internal (e.g., teachers’ beliefs and personality) and external (e.g., student variables, content materials, administrative policies, social trends, and student and peer suggestions) factors influenced the participant teacher’s decision-making. Additionally, a general consistency between the espoused beliefs and real practices was observed. Results and findings of this research provide some pedagogical implications for gifted education, English education, and teacher education. First, this study reveals ways English teachers of the gifted can do, based on the existing curriculum, to provide appropriate differentiation. Second, it suggests the educational authority should attach importance to issues of English talented students’ identification and placement process. Third, in response to the teacher’s controversial theory of fairness, participations in in-service workshops are encouraged to broaden teachers’ understanding about gifted education and professional knowledge. Fourth, it demonstrates how EFL teachers can do to promote learning in mainstream education. Fifth, it is suggested that reflective teaching should be incorporated in teacher education to enhance teaching effectiveness and teacher growth. Moreover, increasing instruction hours for General English per week and recruiting outside part-time faculty to teach enrichment courses for the English gifted class are recommended as well.

Contrails and Induced Cirrus: Optics and Radiation

This paper summarizes the assessment of the current state of knowledge, areas of uncertainties, and recommendations for future efforts, regarding the optical and radiative properties of contrails and contrail cirrus, which have been reported in two detailed subject-specific white papers for the Aviation Climate Change Research Initiative undertaken by the U.S. Federal Aviation Administration. To better estimate the radiative forcing of aircraft-induced cloudiness, there is a pressing need to improve the present understanding of the optical properties of nonspherical ice crystals within contrails and contrail cirrus, and to enhance the global satellite detection and retrieval of these clouds. It is also critical to develop appropriate parameterizations of ice crystal bulk optical properties for climate models on the basis of state-of-the-art scattering simulations and available in situ measurements of ice crystal size and habit distributions within contrails and contrail cirrus. More accurate methods are needed to retrieve the bulk radiative properties of contrails and contrail cirrus to separate natural from anthropogenic ice cloud effects. Such refined techniques should be applied to past and future satellite imagery to develop a contrail climatology that would serve to evaluate contrail radiative forcing more accurately, to determine trends in contrail cirrus, and to guide and validate parameterizations of contrails in numerical weather and climate models. To point the way forward, we recommend four near-term and three long-term research priorities

Single Nucleotide Polymorphisms Other than Factor V Leiden Are Associated with Coagulopathy and Osteonecrosis of the Femoral Head in Chinese Patients

<div><p>Single nucleotide polymorphisms (SNPs) of factor V Leiden have been associated with osteonecrosis of the femoral head (ONFH) in Caucasians but remains controversial in Asians. We used an SNP microarray to screen 55 loci of factor V gene in patients with ONFH of Chinese. Significantly different candidate SNPs at 14 loci were analyzed in 146 patients and 116 healthy controls using MALDI-TOF (matrix-assisted laser desorption/ionization time-of-flight) mass spectrometry and gene sequencing. The factor V Leiden (rs6025) was not found in all participants. Six SNP loci (rs9332595, rs6020, rs9332647, rs3766110, rs10919186, and rs12040141) were confirmed with significant differences in patients but not in controls. The rs6020 G-to-A polymorphism was found in 88.9% of the patients. In addition, a high percentage (87.6%) of the patients had an abnormal coagulation profile that included hyperfibrinogen, elevated fibrinogen degradation products, elevated D-dimer, abnormal protein S, abnormal protein C, or a decrease in anti-thrombin III. Patients with the rs6020 G-to-A polymorphism (mutation) had a higher risk (odds ratio: 4.62; 95% confidence interval: 1.44–14.8) of having coagulation abnormalities than did those without the mutation (wild-type) (χ²<i>p</i>  =  0.006). Our findings suggested that the rs6020 polymorphism might be the genetic trait that accounts for the higher prevalence of ONFH in the Chinese population than in Westerners. Exposure to risk factors such as alcohol and steroids in patients with the rs6020 polymorphism causes coagulation abnormalities and, subsequently, thromboembolisms in the femoral head.</p></div