Model independent inference of the expansion history and implications for the growth of structure

We model the expansion history of the Universe as a Gaussian Process and find constraints on the dark energy density and its low-redshift evolution using distances inferred from the Luminous Red Galaxy (LRG) and Lyman-alpha (Ly$\alpha$) datasets of the Baryon Oscillation Spectroscopic Survey, supernova data from the Joint Light-curve Analysis (JLA) sample, Cosmic Microwave Background (CMB) data from the Planck satellite, and local measurement of the Hubble parameter from the Hubble Space Telescope ($\mathsf H0$). Our analysis shows that the CMB, LRG, Ly$\alpha$, and JLA data are consistent with each other and with a $\Lambda$CDM cosmology, but the ${\mathsf H0}$ data is inconsistent at moderate significance. Including the presence of dark radiation does not alleviate the ${\mathsf H0}$ tension in our analysis. While some of these results have been noted previously, the strength here lies in that we do not assume a particular cosmological model. We calculate the growth of the gravitational potential in General Relativity corresponding to these general expansion histories and show that they are well-approximated by $\Omega_{\rm m}^{0.55}$ given the current precision. We assess the prospects for upcoming surveys to measure deviations from $\Lambda$CDM using this model-independent approach.Comment: 13 pages, 7 figures, code available at: https://github.com/dkirkby/gphis

Implications of a transition in the dark energy equation of state for the H0H_0 and σ8\sigma_8 tensions

We explore the implications of a rapid appearance of dark energy between the redshifts ($z$) of one and two on the expansion rate and growth of perturbations. Using both Gaussian process regression and a parameteric model, we show that this is the preferred solution to the current set of low-redshift ($z<3$) distance measurements if $H_0=73~\rm km\,s^{-1}\,Mpc^{-1}$ to within 1\% and the high-redshift expansion history is unchanged from the $\Lambda$CDM inference by the Planck satellite. Dark energy was effectively non-existent around $z=2$, but its density is close to the $\Lambda$CDM model value today, with an equation of state greater than $-1$ at $z<0.5$. If sources of clustering other than matter are negligible, we show that this expansion history leads to slower growth of perturbations at $z<1$, compared to $\Lambda$CDM, that is measurable by upcoming surveys and can alleviate the $\sigma_8$ tension between the Planck CMB temperature and low-redshift probes of the large-scale structure.Comment: 24 pages, 16 figure

SHOULDER KINETICS DURING PITCHING AND THEIR RELATION TO REPORTED SHOULDER PAIN

The purpose of this study was to identify those variables associated with shoulder pain in young baseball pitchers and develop a logistic regression model capable of predicting shoulder pain. Subjects (n=19) completed shoulder pain documentation before throwing fastball pitches recorded for analysis. At the shoulder, anterior force during cocking and proximal force and internal rotation torque during acceleration were related to shoulder pain (p &#8804; 0.01). Kinetic variables could be used independently to develop a significant logistic regression model. However, when combined, interaction between kinetic variables prevented individual logistic regression coefficients from accounting for a significant magnitude of variability in shoulder pain. Further study is necessary to determine how these variables interact with regard to shoulder pain during pitching

In situ O2 dynamics in submerged Isoetes australis: varied leaf gas permeability influences underwater photosynthesis and internal O2

A unique type of vernal pool are those formed on granite outcrops, as the substrate prevents percolation so that water accumulates in depressions when precipitation exceeds evaporation. The O2 dynamics of small, shallow vernal pools with dense populations of Isoetes australis were studied in situ, and the potential importance of the achlorophyllous leaf bases to underwater net photosynthesis (PN) and radial O2 loss to sediments is highlighted. O2 microelectrodes were used in situ to monitor pO2 in leaves, shallow sediments, and water in four vernal pools. The role of the achlorophyllous leaf bases in gas exchange was evaluated in laboratory studies of underwater PN, loss of tissue water, radial O2 loss, and light microscopy. Tissue and sediment pO2 showed large diurnal amplitudes and internal O2 was more similar to sediment pO2 than water pO2. In early afternoon, sediment pO2 was often higher than tissue pO2 and although sediment O2 declined substantially during the night, it did not become anoxic. The achlorophyllous leaf bases were 34% of the surface area of the shoots, and enhanced by 2.5-fold rates of underwater PN by the green portions, presumably by increasing the surface area for CO2 entry. In addition, these leaf bases would contribute to loss of O2 to the surrounding sediments. Numerous species of isoetids, seagrasses, and rosette-forming wetland plants have a large proportion of the leaf buried in sediments and this study indicates that the white achlorophyllous leaf bases may act as an important area of entry for CO2, or exit for O2, with the surrounding sediment

A Semantic and Syntactic Similarity Measure for Political Tweets

Measurement of the semantic and syntactic similarity of human utterances is essential in allowing machines to understand dialogue with users. However, human language is complex, and the semantic meaning of an utterance is usually dependent upon the context at a given time and learnt experience of the meaning of the words that are used. This is particularly challenging when automatically understanding the meaning of social media, such as tweets, which can contain non-standard language. Short Text Semantic Similarity measures can be adapted to measure the degree of similarity of a pair of tweets. This work presents a new Semantic and Syntactic Similarity Measure (TSSSM) for political tweets. The approach uses word embeddings to determine semantic similarity and extracts syntactic features to overcome the limitations of current measures which may miss identical sequences of words. A large dataset of tweets focusing on the political domain were collected, pre-processed and used to train the word embedding model, with various experiments performed to determine the optimal model and parameters. A selection of tweet pairs were evaluated by humans for semantic equivalence and correlated against the measure. The new measure can be used in a variety of applications, including for identifying and analyzing political narratives. Experiments on three diverse human-labelled test datasets demonstrate that the measure outperforms an existing measure, performs well on tweets from the political domain and may also generalize outside the political domain

RELATIONSHIP BETWEEN UPPER EXTREMITY MASS DISTRIBUTION AND PERFORMANCE IN COLLEGIATE TENNIS PLAYERS

The purpose of this study was to assess the relationship between upper extremity mass distribution and performance in tennis. Eighteen healthy collegiate tennis players consented to participate in this study. The study consisted of body mass distribution analysis using a dual X-ray absorptiometry scan and a simulated performance assessment to gauge accuracy and velocity of various tennis shots. The data collected suggests that mass distribution in the upper extremity is related to both shot velocity and accuracy

A Review of Undergraduate Athletic Training Program Entrance Requirements.

Purpose: Athletic Training (AT) education is undergoing a major change with the transition to the professional Master’s degree. This evolution provides opportunity for faculty to reassess programmatic requirements. Admissions criteria is the first benchmark set for students and may predict future success. Currently, there is no evidence describing common AT entrance requirements. Objective(s): To determine current practices in AT admissions, establish best practices for developing admissions criteria, and discuss the potential impact of the transition to professional master’s degree on the admissions process. Methods: Design: Cross-Sectional Study. Setting(s): Web-based survey in the fall of 2014. Participant(s): 361 undergraduate program directors received the survey; 117 (32.4%) responded. Intervention(s): The survey consisted of 28 questions: 15 demographics questions and 13 questions relating to: Academic structure (1 question), Program admissions procedures (5 questions), and Selection Process (7 questions). Main Outcome Measure(s): Descriptive statistics were calculated for each variable. Results: There were 117 responses, representing all 10 NATA districts. Ninety-seven percent (n=114) use a secondary admission process. Additionally, the majority of programs (n=94, 89.5%) reported using a combination of GPA data when making admissions decisions (i.e. major GPA and overall GPA). Seventy-two percent (n=84) of programs require clinical experience hours (mean 47.64 ±33.68) prior to admission. Personal attributes were assessed through the use of interviews, essays, and other written documents. Conclusions: There are many factors that may affect a program’s outcome. However, it all begins with the individual program’s admission process. To strengthen the program’s quality, faculty members must review their current admission criteria to ensure each requirement is purposeful, relevant, and non-discriminatory

Space Time Coding Over a Multiple-Channel Free Space Optical Link

Free space optical (FSO) communications in the atmosphere are characterized by additive white Gaussian noise (AWGN) and turbulent fading. We propose a combination of spatial and temporal forward error correction (FEC) coding to instantaneously correct for long-duration fades over a multiple channel link. We simulate this over a turbulent channel and identify the probability of outage of such a channel as the most significant channel parameter