452 research outputs found
Preparing athletes and teams for the Olympic Games: experiences and lessons learned from the world's best sport psychologists
As part of an increased effort to understand the most effective ways to psychologically prepare athletes and teams for Olympic competition, a number of sport psychology consultants have offered best-practice insights into working in this context. These individual reports have typically comprised anecdotal reflections of working with particular sports or countries; therefore, a more holistic approach is needed so that developing practitioners can have access to - and utilise - a comprehensive evidence-base.
The purpose of this paper is to provide a panel-type article, which offers lessons and advice for the next generation of aspiring practitioners on preparing athletes and teams for the Olympic Games from some of the world’s most recognised and experienced sport psychologists.
The sample comprised 15 sport psychology practitioners who, collectively, have accumulated over 200 years of first-hand experience preparing athletes and/or teams from a range of nations for six summer and five winter Olympic Games. Interviews with the participants revealed 28 main themes and 5 categories: Olympic stressors, success and failure lessons, top tips for neophyte practitioners, differences within one’s own consulting work, and multidisciplinary consulting. It is hoped that the findings of this study can help the next generation of sport psychologists better face the realities of Olympic consultancy and plan their own professional development so that, ultimately, their aspirations to be the world’s best can become a reality
Col-OSSOS: Colors of the Interstellar Planetesimal 1I/`Oumuamua
The recent discovery by Pan-STARRS1 of 1I/2017 U1 (`Oumuamua), on an unbound
and hyperbolic orbit, offers a rare opportunity to explore the planetary
formation processes of other stars, and the effect of the interstellar
environment on a planetesimal surface. 1I/`Oumuamua's close encounter with the
inner Solar System in 2017 October was a unique chance to make observations
matching those used to characterize the small-body populations of our own Solar
System. We present near-simultaneous g, r, and J photometry
and colors of 1I/`Oumuamua from the 8.1-m Frederick C. Gillett Gemini North
Telescope, and photometry from the 4.2 m William Herschel Telescope. Our
grJ observations are directly comparable to those from the
high-precision Colours of the Outer Solar System Origins Survey (Col-OSSOS),
which offer unique diagnostic information for distinguishing between outer
Solar System surfaces. The J-band data also provide the highest signal-to-noise
measurements made of 1I/`Oumuamua in the near-infrared. Substantial, correlated
near-infrared and optical variability is present, with the same trend in both
near-infrared and optical. Our observations are consistent with 1I/`Oumuamua
rotating with a double-peaked period of hours and being a
highly elongated body with an axial ratio of at least 5.3:1, implying that it
has significant internal cohesion. The color of the first interstellar
planetesimal is at the neutral end of the range of Solar System and
solar-reflectance colors: it is like that of some dynamically excited objects
in the Kuiper belt and the less-red Jupiter Trojans.Comment: Accepted to ApJ
Col-OSSOS: The Colours of the Outer Solar System Origins Survey
The Colours of the Outer Solar System Origins Survey (Col-OSSOS) is acquiring
near-simultaneous , , and photometry of unprecedented precision with
the Gemini North Telescope, targeting nearly a hundred trans-Neptunian objects
(TNOs) brighter than mag discovered in the Outer Solar System
Origins Survey. Combining the optical and near-infrared photometry with the
well-characterized detection efficiency of the Col-OSSOS target sample will
provide the first flux-limited compositional dynamical map of the outer Solar
System. In this paper, we describe our observing strategy and detail the data
reduction processes we employ, including techniques to mitigate the impact of
rotational variability. We present optical and near-infrared colors for 35
TNOs. We find two taxonomic groups for the dynamically excited TNOs, the
neutral and red classes, which divide at . Based on simple
albedo and orbital distribution assumptions, we find that the neutral class
outnumbers the red class, with a ratio of 4:1 and potentially as high as 11:1.
Including in our analysis constraints from the cold classical objects, which
are known to exhibit unique albedos and colors, we find that within our
measurement uncertainty, our observations are consistent with the primordial
Solar System protoplanetesimal disk being neutral-class-dominated, with two
major compositional divisions in color space.Comment: Accepted to ApJS; on-line supplemental files will be available with
the AJS published version of the pape
Col-OSSOS: Z-Band Photometry Reveals Three Distinct TNO Surface Types
Several different classes of trans-Neptunian objects (TNOs) have been
identified based on their optical and near-infrared colors. As part of the
Colours of the Outer Solar System Origins Survey, we have obtained , ,
and band photometry of 26 TNOs using Subaru and Gemini Observatories.
Previous color surveys have not utilized band reflectance, and the
inclusion of this band reveals significant surface reflectance variations
between sub-populations. The colors of TNOs in and show obvious
structure, and appear consistent with the previously measured bi-modality in
. The distribution of colors of the two dynamically excited surface types
can be modeled using the two-component mixing models from Fraser \& Brown
(2012). With the combination of and , the dynamically excited
classes can be separated cleanly into red and neutral surface classes. In and , the two dynamically excited surface groups are also clearly
distinct from the cold classical TNO surfaces, which are red, with
0.85 and 0.6, while all dynamically excited objects
with similar colors exhibit redder colors. The band photometry
makes it possible for the first time to differentiate the red excited TNO
surfaces from the red cold classical TNO surfaces. The discovery of different
colors for these cold classical TNOs makes it possible to search for cold
classical surfaces in other regions of the Kuiper belt and to completely
separate cold classical TNOs from the dynamically excited population, which
overlaps in orbital parameter space.Comment: 11 pages, 2 figures, Accepted to A
Discovery of A New Retrograde Trans-Neptunian Object: Hint of A Common Orbital Plane for Low Semi-Major Axis, High Inclination TNOs and Centaurs
Although the majority of Centaurs are thought to have originated in the
scattered disk, with the high-inclination members coming from the Oort cloud,
the origin of the high inclination component of trans-Neptunian objects (TNOs)
remains uncertain. We report the discovery of a retrograde TNO, which we
nickname "Niku", detected by the Pan-STARRS 1 Outer Solar System Survey. Our
numerical integrations show that the orbital dynamics of Niku are very similar
to that of 2008 KV (Drac), with a half-life of Myr. Comparing
similar high inclination TNOs and Centaurs ( AU, ), we find that these objects exhibit a surprising clustering of
ascending node, and occupy a common orbital plane. This orbital configuration
has high statistical significance: 3.8-. An unknown mechanism is
required to explain the observed clustering. This discovery may provide a
pathway to investigate a possible reservoir of high-inclination objects.Comment: 18 pages, 4 figures, 1 table, accepted for publication in ApJ Letter
Metrology Camera System of Prime Focus Spectrograph for Subaru Telescope
The Prime Focus Spectrograph (PFS) is a new optical/near-infrared multi-fiber
spectrograph designed for the prime focus of the 8.2m Subaru telescope. PFS
will cover a 1.3 degree diameter field with 2394 fibers to complement the
imaging capabilities of Hyper SuprimeCam. To retain high throughput, the final
positioning accuracy between the fibers and observing targets of PFS is
required to be less than 10um. The metrology camera system (MCS) serves as the
optical encoder of the fiber motors for the configuring of fibers. MCS provides
the fiber positions within a 5um error over the 45 cm focal plane. The
information from MCS will be fed into the fiber positioner control system for
the closed loop control. MCS will be located at the Cassegrain focus of Subaru
telescope in order to to cover the whole focal plane with one 50M pixel Canon
CMOS camera. It is a 380mm Schmidt type telescope which generates a uniform
spot size with a 10 micron FWHM across the field for reasonable sampling of
PSF. Carbon fiber tubes are used to provide a stable structure over the
operating conditions without focus adjustments. The CMOS sensor can be read in
0.8s to reduce the overhead for the fiber configuration. The positions of all
fibers can be obtained within 0.5s after the readout of the frame. This enables
the overall fiber configuration to be less than 2 minutes. MCS will be
installed inside a standard Subaru Cassgrain Box. All components that generate
heat are located inside a glycol cooled cabinet to reduce the possible image
motion due to heat. The optics and camera for MCS have been delivered and
tested. The mechanical parts and supporting structure are ready as of spring
2016. The integration of MCS will start in the summer of 2016.Comment: 11 pages, 15 figures. SPIE proceeding. arXiv admin note: text overlap
with arXiv:1408.287
The shortest cut in brane cosmology
We consider brane cosmology studying the shortest null path on the brane for
photons, and in the bulk for gravitons. We derive the differential equation for
the shortest path in the bulk for a 1+4 cosmological metric. The time cost and
the redshifts for photons and gravitons after traveling their respective path
are compared. We consider some numerical solutions of the shortest path
equation, and show that there is no shortest path in the bulk for the
Randall-Sundrum vacuum brane solution, the linear cosmological solution of
Bin\'etruy, et al for , and for some expanding brane
universes.Comment: 20 pages, 7 figure
Chiral photocurrent in a Quasi-1D TiS3 (001) phototransistor
The presence of in-plane chiral effects, hence spin–orbit coupling, is evident in the changes in the photocurrent produced in a TiS3(001) field-effect phototransistor with left versus right circularly polarized light. The direction of the photocurrent is protected by the presence of strong spin–orbit coupling and the anisotropy of the band structure as indicated in NanoARPES measurements. Dark electronic transport measurements indicate that TiS3 is n-type and has an electron mobility in the range of 1–6 cm2V−1s−1. I–V measurements under laser illumination indicate the photocurrent exhibits a bias directionality dependence, reminiscent of bipolar spin diode behavior. Because the TiS3 contains no heavy elements, the presence of spin–orbit coupling must be attributed to the observed loss of inversion symmetry at the TiS3(001) surface
Multi-user video streaming using unequal error protection network coding in wireless networks
In this paper, we investigate a multi-user video streaming system applying unequal error protection (UEP) network coding (NC) for simultaneous real-time exchange of scalable video streams among multiple users. We focus on a simple wireless scenario where users exchange encoded data packets over a common central network node (e.g., a base station or an access point) that aims to capture the fundamental system behaviour. Our goal is to present analytical tools that provide both the decoding probability analysis and the expected delay guarantees for different importance layers of scalable video streams. Using the proposed tools, we offer a simple framework for design and analysis of UEP NC based multi-user video streaming systems and provide examples of system design for video conferencing scenario in broadband wireless cellular networks
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