Caffeine and Sprint Performance in Habitual and Caffeine Naive Participants

Caffeine is thought to provide ergogenic benefits during endurance performance. However, there is limited research on the effects of caffeine on anaerobic sports performance. The purpose of this study was to examine the effects of 6 mg·kg-1 of caffeine on repeated sprint performance. The sample included active college students (N = 18), classified as habitual caffeine or caffeine naïve users. Participants completed a 12 x 30-m sprint test with 35 s rest intervals between sprints. Ratings of Perceived Exertion were collected every 3rd sprint. Height and body mass were measured and participants accommodated to the sprint test on Day 1. Participants were randomly assigned to the placebo or caffeine condition on Day 2 and the treatment was reversed on Day 3. Caffeine was ingested in a sports drink 1 h prior to performing the sprints. Caffeine produced a significantly faster best sprint time compared to the placebo trial, F (1, 17) = 7.38, MSE = .02, H-F p = .02. However, no significant difference was found between caffeine supplementation and placebo on time to complete the total sprint test. Additionally, no significant difference was found in sprint times with caffeine supplementation by sex or between caffeine-naïve and habitual caffeine users. Finally, a significantly higher average RPE was found with caffeine supplementation as compared to the placebo, t (1, 17) = 2.92, d = .38, p = .01. Caffeine has the potential to enhance sprint performance however, further research with women and habitual caffeine consumers is needed

Acute Effects of Static and Proprioceptive Neuromuscular Facilitation Stretching on Agility Performance in Elite Youth Soccer Players

Int J Exerc Sci 5(2) : 97-105, 2012. A warm-up is an important part of preparation for a soccer match. Stretching is typically part of the warm-up however, debate exists as to the most appropriate type of stretching to perform. The purpose of this study was to examine the effects of static and proprioceptive neuromuscular facilitation (PNF) stretching on soccer-specific agility performance in 14 male elite, premier league youth soccer players. Participants completed 4 trials of the Balsom agility test while dribbling a soccer ball. Height, age, and body mass were collected in trial 1 and participants were accommodated to the agility test during trials 1 and 2. Trials 3 and 4 were the static and PNF treatment trials that were administered after a standardized warm-up (control) in a randomized and counterbalanced manner. There were no significant differences between the difference scores of the static and PNF stretching conditions, P = .66. Furthermore, no significant differences were found between the control and stretching trials for static stretching, P = .15 or between the control and stretching trials for PNF stretching, P = .58. Neither mode of stretching significantly affected agility performance. More research is needed to determine the chronic effects of PNF stretching on agility performance

Quaternary sea level changes in Scotland

This paper summarises developments in understanding sea level change during the Quaternary in Scotland since the publication of the Quaternary of Scotland Geological Conservation Review volume Quaternary of Scotland in 1993. We present a review of progress in methodology, particularly in the study of sediments in isolation basins and estuaries as well as in techniques in the field and laboratory, which have together disclosed greater detail in the record of relative sea level (RSL) change than was available in 1993. However, progress in determining the record of RSL change varies in different areas. Studies of sediments and stratigraphy offshore on the continental shelf have increased greatly, but the record of RSL change there remains patchy. Studies onshore have resulted in improvements in the knowledge of rock shorelines, including the processes by which they are formed, but much remains to be understood. Studies of Late Devensian and Holocene RSLs around present coasts have improved knowledge of both the extent and age range of the evidence. The record of RSL change on the W and NW coasts has disclosed a much longer dated RSL record than was available before 1993, possibly with evidence of Meltwater Pulse 1A, while studies in estuaries on the E and SW coasts have disclosed widespread and consistent fluctuations in Holocene RSLs. Evidence for the meltwater pulse associated with the Early Holocene discharge of Lakes Agassiz-Ojibway in N America has been found on both E and W coasts. The effects of the impact of storminess, in particular in cliff-top storm deposits, have been widely identified. Further information on the Holocene Storegga Slide tsunami has enabled a better understanding of the event but evidence for other tsunami events on Scottish coasts remains uncertain. Methodological developments have led to new reconstructions of RSL change for the last 2000 years, utilising state-of-the-art GIA models and alongside coastal biostratigraphy to determine trends to compare with modern tide gauge and documentary evidence. Developments in GIA modelling have provided valuable information on patterns of land uplift during and following deglaciation. The studies undertaken raise a number of research questions which will require addressing in future work

Adolescent Perceptions of Injury and Pressures of Returning to Sport: A Retrospective Qualitative Analysis

The increase in sport participation among adolescents has led to the rise in sport-related injuries, many of which have unique characteristics based on the patient, their perceptions, and the pressures faced when returning to sport. The purpose of this study was to identify the underlying factors that contributed to adolescents’ perceptions of injury and the various pressures they experienced when returning to sport. Two themes emerged from the study: support and fear. Support was provided to participants through development, care, and the environment. Fear was the factor that affected the participant in their return to sport, which came in the form of worry and doubt

Linear independence in linear systems on elliptic curves

Let $E$ be an elliptic curve, with identity $O$, and let $C$ be a cyclic subgroup of odd order $N$, over an algebraically closed field $k$ with $\operatorname{char} k \nmid N$. For $P \in C$, let $s_P$ be a rational function with divisor $N \cdot P - N \cdot O$. We ask whether the $N$ functions $s_P$ are linearly independent. For generic $(E,C)$, we prove that the answer is yes. We bound the number of exceptional $(E,C)$ when $N$ is a prime by using the geometry of the universal generalized elliptic curve over $X_1(N)$. The problem can be recast in terms of sections of an arbitrary degree $N$ line bundle on $E$.Comment: 10 page

The Environment of M85 optical transient 2006-1: constraints on the progenitor age and mass

M85 optical transient 2006-1 (M85 OT 2006-1) is the most luminous member of the small family of V838 Mon-like objects, whose nature is still a mystery. This event took place in the Virgo cluster of galaxies and peaked at an absolute magnitude of I~-13. Here we present Hubble Space Telescope images of M85 OT 2006-1 and its environment, taken before and after the eruption, along with a spectrum of the host galaxy at the transient location. We find that the progenitor of M85 OT 2006-1 was not associated with any star forming region. The g and z-band absolute magnitudes of the progenitor were fainter than about -4 and -6 mag, respectively. Therefore, we can set a lower limit of ~50 Myr on the age of the youngest stars at the location of the progenitor that corresponds to a mass of <7 solar mass. Previously published line indices suggest that M85 has a mean stellar age of 1.6+/-0.3 Gyr. If this mean age is representative of the progenitor of M85 OT 2006-1, then we can further constrain its mass to be less than 2 solar mass. We compare the energetics and mass limit derived for the M85 OT 2006-1 progenitor with those expected from a simple model of violent stellar mergers. Combined with further modeling, these new clues may ultimately reveal the true nature of these puzzling events.Comment: 4 pages, accepted to Ap

Direct observation of growth and collapse of a Bose-Einstein condensate with attractive interactions

The dynamical behavior of Bose-Einstein condensation (BEC) in a gas with attractive interactions is striking. Quantum theory predicts that BEC of a spatially homogeneous gas with attractive interactions is precluded by a conventional phase transition into either a liquid or solid. When confined to a trap, however, such a condensate can form provided that its occupation number does not exceed a limiting value. The stability limit is determined by a balance between self-attraction and a repulsion arising from position-momentum uncertainty under conditions of spatial confinement. Near the stability limit, self-attraction can overwhelm the repulsion, causing the condensate to collapse. Growth of the condensate, therefore, is punctuated by intermittent collapses, which are triggered either by macroscopic quantum tunneling or thermal fluctuation. Previous observation of growth and collapse has been hampered by the stochastic nature of these mechanisms. Here we reduce the stochasticity by controlling the initial number of condensate atoms using a two-photon transition to a diatomic molecular state. This enables us to obtain the first direct observation of the growth of a condensate with attractive interactions and its subsequent collapse.Comment: 10 PDF pages, 5 figures (2 color), 19 references, to appear in Nature Dec. 7 200

HI intensity mapping with the MIGHTEE survey: power spectrum estimates

Intensity mapping (IM) with neutral hydrogen is a promising avenue to probe the large scale structure of the Universe. With MeerKAT single-dish measurements, we are constrained to scales $>1$ degree, and this will allow us to set important constraints on the Baryon acoustic oscillations and redshift space distortions. However, with MeerKAT's interferometric observation, we can also probe relevant cosmological scales. In this paper, we establish that we can make a statistical detection of HI with one of MeerKAT's existing large survey projects (MIGHTEE) on semi-linear scales, which will provide a useful complementarity to the single-dish IM. We present a purpose-built simulation pipeline that emulates the MIGHTEE observations and forecast the constraints that can be achieved on the HI power spectrum at $z = 0.27$ for $k > 0.3$ $\rm{Mpc}^{-1}$ using the foreground avoidance method. We present the power spectrum estimates with the current simulation on the COSMOS field that includes contributions from HI, noise and point source models from the data itself. The results from our \textit{visibility} based pipeline are in good agreement to the already available MIGHTEE data. This paper demonstrates that MeerKAT can achieve very high sensitivity to detect HI with the full MIGHTEE survey on semi-linear scales (signal-to-noise ratio $> 7$ at $k=0.49$ $\rm{Mpc}^{-1}$) which are instrumental in probing cosmological quantities such as the spectral index of fluctuation, constraints on warm dark matter, the quasi-linear redshift space distortions and the measurement of the HI content of the Universe up to $z\sim 0.5$.Comment: 12 pages, 8 figures, Submitted to MNRAS, comments welcom