897 research outputs found
Pointed Admissible G-Covers and G-equivariant Cohomological Field Theories
For any finite group G we define the moduli space of pointed admissible
G-covers and the concept of a G-equivariant cohomological field theory
(G-CohFT), which, when G is the trivial group, reduce to the moduli space of
stable curves and a cohomological field theory (CohFT), respectively. We prove
that by taking the "quotient" by G, a G-CohFT reduces to a CohFT. We also prove
that a G-CohFT contains a G-Frobenius algebra, a G-equivariant generalization
of a Frobenius algebra, and that the "quotient" by G agrees with the obvious
Frobenius algebra structure on the space of G-invariants, after rescaling the
metric.
We also introduce the moduli space of G-stable maps into a smooth, projective
variety X with G action. Gromov-Witten-like invariants of these spaces provide
the primary source of examples of G-CohFTs. Finally, we explain how these
constructions generalize (and unify) the Chen-Ruan orbifold Gromov-Witten
invariants of the global quotient [X/G] as well as the ring H*(X,G) of Fantechi
and Goettsche.Comment: Corrected proof of the trace axiom and made minor typo corrections.
13 figures. Uses Paul Taylor's diagrams packag
\u3ci\u3eThe Court Years 1939-1975: The Autobiography of William O. Douglas\u3c/i\u3e (1980)
Few Americans would claim objectivity on the subject of William O. Douglas. He inspired powerful reactions. I start by stating my deeply held admiration for Justice Douglas, a respect nurtured at a distance and from his writings. His writings brought Douglas the man and Douglas the Justice close to many who never met him. His words show him to be a man who cared profoundly about the world, its people, his country, and the law. Decades of American law students, particularly those like me who studied law in the 1960\u27s and 1970\u27s, listened to Justice Douglas, whether he was in the majority or, as often was the case, in dissent. As an admirer, I read and now review his account of life as an associate justice of the Supreme Court of the United States
Impairment of Cycling Capacity in the Heat in Well-Trained Endurance Athletes After High-Intensity Short-Term Heat Acclimation
Purpose: to investigate the effects of short-term, high-intensity interval-training (HIIT) heat acclimation (HA). Methods: male cyclists/triathletes were assigned into either an HA (n = 13) or a comparison (COMP, n = 10) group. HA completed 3 cycling heat stress tests (HSTs) to exhaustion (60% Wmax; HST1, pre-HA; HST2, post-HA; HST3, 7 d post-HA). HA consisted of 30-min bouts of HIIT cycling (6 min at 50% Wmax, then 12 × 1-min 100%-Wmax bouts with 1-min rests between bouts) on 5 consecutive days. COMP completed HST1 and HST2 only. HST and HA trials were conducted in 35°C/50% relative humidity. Cycling capacity and physiological and perceptual data were recorded. Results: cycling capacity was impaired after HIIT HA (77.2 [34.2] min vs 56.2 [24.4] min, P = .03) and did not return to baseline after 7 d of no HA (59.2 [37.4] min). Capacity in HST1 and HST2 was similar in COMP (43.5 [8.3] min vs 46.8 [15.7] min, P = .54). HIIT HA lowered resting rectal (37.0°C [0.3°C] vs 36.8°C [0.2°C], P = .05) and body temperature (36.0°C [0.3°C] vs 35.8°C [0.3°C], P = .03) in HST2 compared with HST1 and lowered mean skin temperature (35.4°C [0.5°C] vs 35.1°C [0.3°C], P = .02) and perceived strain on day 5 compared with day 1 of HA. All other data were unaffected. Conclusions: cycling capacity was impaired in the heat after 5 d of consecutive HIIT HA despite some heat adaptation. Based on data, this approach is not recommended for athletes preparing to compete in the heat; however, it is possible that it may be beneficial if a state of overreaching is avoided
The effect of head and neck per-cooling on neuromuscular fatigue following exercise in the heat
The effect of localised head and neck per-cooling on central and peripheral fatigue during high thermal strain was investigated. Fourteen participants cycled for 60 min at 50% peak oxygen uptake on 3 occasions: thermoneutral control (CON; 18 °C), hot (HOT; 35 °C), and HOT with head and neck cooling (HOTcooling). Maximal voluntary force (MVF) and central activation ratio (CAR) of the knee extensors were measured every 30 s during a sustained maximal voluntary contraction (MVC). Triplet peak force was measured following cycling, before and after the MVC. Rectal temperatures were higher in HOTcooling (39.2 ± 0.6 °C) and HOT (39.3 ± 0.5 °C) than CON (38.1 ± 0.3 °C; P < 0.05). Head and neck thermal sensation was similar in HOTcooling (4.2 ± 1.4) and CON (4.4 ± 0.9; P > 0.05) but lower than HOT (5.9 ± 1.5; P < 0.05). MVF and CAR were lower in HOT than CON throughout the MVC (P < 0.05). MVF and CAR were also lower in HOTcooling than CON at 5, 60, and 120 s, but similar at 30 and 90 s into the MVC (P > 0.05). Furthermore, they were greater in HOTcooling than HOT at 30 s, whilst triplet peak force was preserved in HOT after MVC. These results provide evidence that central fatigue following exercise in the heat is partially attenuated with head and neck cooling, which may be at the expense of greater peripheral fatigue
Surface Electromagnetic Waves with Damping. II. Anisotropic Media
The Technique of Plotting the Attenuated-Total-Reflection (ATR) Reflectance as a Function of Both Frequency and Incident Angle using a Three-Dimensional Plot is Applied to Surface Electromagnetic Waves (SEW) in a Uniaxial Material, MnF2. It is Shown that Dispersion Curves Calculated Without Absorption Do Not Completely Describe the ATR Reflectivity. Experimental Data Confirming the Reflectance Surface Features Are Presented. Also, Additional Minima in the Reflectance Surface Not Associated with SEW Are Discussed. © 1977 the American Physical Society
Saturation Effects in a Tunable Coherent Near-Infrared Source
A Saturation Effect in a Tunable Infrared Source Utilizing Four-Wave Parametric Conversion in Potassium Vapor is Reported and is Shown to Be the Result of Parasitic Oscillations. a Hundredfold Increase over Previously Attained Power Levels Has Been Affected Via Elimination of These Oscillations
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