547 research outputs found
A Spitzer Five-Band Analysis of the Jupiter-Sized Planet TrES-1
With an equilibrium temperature of 1200 K, TrES-1 is one of the coolest hot
Jupiters observed by {\Spitzer}. It was also the first planet discovered by any
transit survey and one of the first exoplanets from which thermal emission was
directly observed. We analyzed all {\Spitzer} eclipse and transit data for
TrES-1 and obtained its eclipse depths and brightness temperatures in the 3.6
{\micron} (0.083 % {\pm} 0.024 %, 1270 {\pm} 110 K), 4.5 {\micron} (0.094 %
{\pm} 0.024 %, 1126 {\pm} 90 K), 5.8 {\micron} (0.162 % {\pm} 0.042 %, 1205
{\pm} 130 K), 8.0 {\micron} (0.213 % {\pm} 0.042 %, 1190 {\pm} 130 K), and 16
{\micron} (0.33 % {\pm} 0.12 %, 1270 {\pm} 310 K) bands. The eclipse depths can
be explained, within 1 errors, by a standard atmospheric model with
solar abundance composition in chemical equilibrium, with or without a thermal
inversion. The combined analysis of the transit, eclipse, and radial-velocity
ephemerides gives an eccentricity , consistent
with a circular orbit. Since TrES-1's eclipses have low signal-to-noise ratios,
we implemented optimal photometry and differential-evolution Markov-chain Monte
Carlo (MCMC) algorithms in our Photometry for Orbits, Eclipses, and Transits
(POET) pipeline. Benefits include higher photometric precision and \sim10 times
faster MCMC convergence, with better exploration of the phase space and no
manual parameter tuning.Comment: 17 pages, Accepted for publication in Ap
Non-Linear Advanced Control of the LHC Inner Triplet Heat Exchanger Test Unit
The future Large Hadron Collider (LHC) at CERN will include eight interaction region final focus magnet systems, the so-called "Inner Triplet", one on each side of the four beam collision points. The Inner Triplets will be cooled in a static bath of pressurized He II nominally at 1.9 K. This temperature is a control parameter and has very severe constraints in order to avoid the transition from the superconducting to normal resistive state. The main difference in these special zones with respect to a regular LHC cell is higher dynamic heat load unevenly distributed which modifies largely the process characteristics and hence the controller performance. Several control strategies have already been tested at CERN in a pilot plant (LHC String Test) which reproduced a LHC half-cell. In order to validate a common control structure along the whole LHC ring, a Nonlinear Model Predictive Control (NMPC) has been developed and implemented in the Inner Triplet Heat Exchanger Unit (IT-HXTU) at CERN. Automation of the Inner Triplet setup and the advanced control techniques deployed based on the Model Based Predictive Control (MBPC) principle are presented
Impact of MgII interstellar medium absorption on near-ultraviolet exoplanet transit measurements
Ultraviolet (UV) transmission spectroscopy probes atmospheric escape, which
has a significant impact on planetary atmospheric evolution. If unaccounted
for, interstellar medium absorption (ISM) at the position of specific UV lines
might bias transit depth measurements, and thus potentially affect the
(non-)detection of features in transmission spectra. Ultimately, this is
connected to the so called ``resolution-linked bias'' (RLB) effect. We present
a parametric study quantifying the impact of unresolved or unconsidered ISM
absorption in transit depth measurements at the position of the MgII h&k
resonance lines (i.e. 2802.705 {\AA} and 2795.528 {\AA} respectively) in the
near-ultraviolet spectral range. We consider main-sequence stars of different
spectral types and vary the shape and amount of chromospheric emission, ISM
absorption, and planetary absorption, as well as their relative velocities. We
also evaluate the role played by integration bin and spectral resolution. We
present an open-source tool enabling one to quantify the impact of unresolved
or unconsidered MgII ISM absorption in transit depth measurements. We further
apply this tool to a few already or soon to be observed systems. On average, we
find that ignoring ISM absorption leads to biases in the MgII transit depth
measurements comparable to the uncertainties obtained from the observations
published to date. However, considering the bias induced by ISM absorption
might become necessary when analysing observations obtained with the next
generation space telescopes with UV coverage (e.g. LUVOIR, HABEX), which will
provide transmission spectra with significantly smaller uncertainties compared
to what obtained with current facilities (e.g. HST).Comment: Accepted for publication in MNRA
Applying Advanced Control Techniques for Temperature Regulation of the LHC Superconducting Magnets
The temperature of the superconducting magnets for the future LHC accelerator is a control parameter with strict operating constraints imposed by (a) the maximum temperature at which the magnets can o perate, (b) the cooling capacity of the cryogenic system, (c) the variability of applied heat loads and (d) the accuracy of the instrumentation. A temperature regulation with narrow control band can i n principle be achieved by implementing a Model Predictive Control (MPC)-type controller. For this purpose, and for investigating the behaviour of the cooling system, a simulation program has been dev eloped. A prototype MPC controller has been installed and completed its first run
Association Between Single-Leg Agility and Single-Leg Vertical Jumping Performance in Active Adults
The vertical jump is crucial in sports and indicates lower body explosiveness. Additionally, vertical jumping requires landing bilaterally or unilaterally. PURPOSE: To determine any differences in unilateral vertical jump performance when landing unilaterally or bilaterally. METHODS: Thirty recreationally trained individuals (age = 23.5 ± 2.2 years) performed three trials of vertical jumps under four different conditions in random order (unilateral-left vertical jump with bilateral landing, unilateral-right vertical jump with bilateral landing, unilateral-left vertical jump with ipsilateral landing, and unilateral-right vertical jump with ipsilateral landing). Kinetic data (peak force, relative peak force, peak power, and relative peak power) was obtained from all jumps at 1000 Hz sampling rate. The average score between trials for the vertical jump were used for statistical analysis in SPSS 25. Independent T-tests were used to find differences in vertical jump measures depending on landing condition with p-value at 0.05. RESULTS: No significant differences between limbs in jump height (Right = 0.08 cm ± 0.04; Left cm = 0.11 ± 0.05), peak force (Right = 473.3 N ± 135.6; Left = 600.1 N ± 182.6), relative peak force (Right = 6.8 N*kg ± 2.6; Left = 7.8 N*kg ± 1.9), peak power (Right = 1505.4 W ± 524.5; Left = 1934.9 W ± 771.9), and relative peak power (Right = 21.3 W*kg ± 7.2; Left = 25.5 W*kg ± 5.8) during unilateral vertical jumps between the landing conditions (p \u3e 0.05). CONCLUSION: It appears that landing conditions do not affect unilateral jump performance in recreationally trained athletes
Instrumentation, Field Network and Process Automation for the Cryogenic System of the LHC Test String
CERN is now setting up String 2, a full-size prototype of a regular cell of the LHC arc. It is composed of two quadrupole, six dipole magnets, and a separate cryogenic distribution line (QRL) for the supply and recovery of the cryogen. An electrical feed box (DFB), with up to 38 High Temperature Superconducting (HTS) leads, powers the magnets. About 700 sensors and actuators are distributed along four Profibus DP and two Profibus PA field buses. The process automation is handled by two controllers, running 126 Closed Control Loops (CCL). This paper describes the cryogenic control system, associated instrumentation, and their commissioning
The Cryogenic System for the LHC Test String 2: Design, Commissioning and Operation
A 107-m long superconducting magnet string representing a full-cell of the LHC machine was designed for assembly and commissioning at CERN in order to validate the final design choices. This new facility, thereafter called Test String 2, and its cryogenic infrastructure cons ist of feed and return boxes coupled via transfer lines to a 6 kW @ 4.5 K refrigerator and to a low pressure pumping group, a separate cryogenic distribution line, an electrical feed box with HTS current leads, 2 quadrupole and 6 dipole prototype and pre-series superconducting magnets
The Relationship between Squat Jump Performance and Sprint Profile in Collegiate Track and Field Athletes
The squat jump (SJ) necessitates the inter-play of various biomechanical components for better jump performance. Good sprint performance requires the inter-play of many of the same biomechanical components. Researchers have previously examined how the speed, force, velocity, and power interact during sprinting, but have yet to examine how these measures are associated with SJ performance measures. PURPOSE: Examine the relationship between squat jump performance measures and the sprint profile measurements of collegiate track and field athletes. METHODS: Twenty-five athletes (18 males and 7 females) completed two squat jump trials with a linear encoder attached to a 45 lbs. bar placed on the athlete’s upper back. Measures of interest during the concentric phase of the SJ included jump height, maximum force, maximum velocity, maximum power, and rate of force development. Athletes then completed two 30-meter acceleration sprints. The MySprint mobile application was used to acquire the athlete’s sprint profile and to assess maximal theoretical horizontal force, maximal theoretical velocity, optimal velocity, maximal theoretical power, maximal speed, maximal ratio of force, force-velocity slope, and decrease in ratio of force. The best trial was used for statistical analysis. Pearson’s or Spearman’s correlation coefficients were conducted between SJ measures and sprint profile measures. RESULTS: There was a positive correlation between SJ height and maximal speed (r = 0.402; p = 0.042). Maximal power during the SJ was positively correlated with maximal speed (r = 0.476; p = 0.014); optimal velocity (r = 0.469; p = 0.018); maximal theoretical power (r = 0.462; p = 0.018); maximal theoretical velocity (r = 0.452; p = 0.021); theoretical horizontal force (r = 0.431; p = 0.028); and maximal ratio force (r = 0.428; p = 0.029). Maximal velocity during the SJ was correlated with maximal speed (r = 0.519; p = 0.007); maximal theoretical velocity (r = 0.499; p = 0.010); optimal velocity (r = 0.486; p = 0.014); and maximal theoretical power (r = 0.484; p = 0.012). No other correlations were significant. CONCLUSION: Maximal velocity and power during the concentric phase of the SJ are moderately to strongly correlated with maximal sprinting speed, velocity, and power. SJ height is positively correlated with maximum sprint speed. There is a lack of significant correlations between other measures of the SJ and sprint profile measures. SJ power and velocity are correlated with sprint performance, therefore power and velocity improved through plyometric SJ training may be transferable to achieve better sprint performance
Patterns of Public Participation: Opportunity Structures and Mobilization from a Cross-National Perspective
PURPOSE: The paper summarizes data from twelve countries, chosen to exhibit wide variation, on the role and place of public participation in the setting of priorities. It seeks to exhibit cross-national patterns in respect of public participation, linking those differences to institutional features of the countries concerned. DESIGN/METHODOLOGY/APPROACH: The approach is an example of case-orientated qualitative assessment of participation practices. It derives its data from the presentation of country case studies by experts on each system. The country cases are located within the historical development of democracy in each country. FINDINGS: Patterns of participation are widely variable. Participation that is effective through routinized institutional processes appears to be inversely related to contestatory participation that uses political mobilization to challenge the legitimacy of the priority setting process. No system has resolved the conceptual ambiguities that are implicit in the idea of public participation. ORIGINALITY/VALUE: The paper draws on a unique collection of country case studies in participatory practice in prioritization, supplementing existing published sources. In showing that contestatory participation plays an important role in a sub-set of these countries it makes an important contribution to the field because it broadens the debate about public participation in priority setting beyond the use of minipublics and the observation of public representatives on decision-making bodies
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