Multiscale Technicolor and the Zbb-bar Vertex

We estimate the correction to the Zbb-bar vertex arising from the exchanges of the sideways extended technicolor (ETC) boson and the flavor-diagonal ETC boson in the multiscale walking technicolor model. The obtained result is too large to explain the present data. However, if we introduce a new self- interaction for the top quark to induce the top quark condensate serving as the origin of the large top quark mass, the corrected R_b=Gamma_b/Gamma_h can be consistent with the recent LEP data. The corresponding correction to R_c=Gamma_c/Gamma_h is shown to be negligibly small.Comment: 9-page LaTex fil

Molecular structure of highly-excited resonant states in 24^{24}Mg and the corresponding 8^8Be+16^{16}O and 12^{12}C+12^{12}C decays

Exotic $^8$Be and $^{12}$C decays from high-lying resonances in $^{24}$Mg are analyzed in terms of a cluster model. The calculated quantities agree well with the corresponding experimental data. It is found that the calculated decay widths are very sensitive to the angular momentum carried by the outgoing cluster. It is shown that this property makes cluster decay a powerful tool to determine the spin as well as the molecular structures of the resonances.Comment: 17 pages, no figur

Steady-state Ab Initio Laser Theory: Generalizations and Analytic Results

We improve the steady-state ab initio laser theory (SALT) of Tureci et al. by expressing its fundamental self-consistent equation in a basis set of threshold constant flux states that contains the exact threshold lasing mode. For cavities with non-uniform index and/or non-uniform gain, the new basis set allows the steady-state lasing properties to be computed with much greater efficiency. This formulation of the SALT can be solved in the single-pole approximation, which gives the intensities and thresholds, including the effects of nonlinear hole-burning interactions to all orders, with negligible computational effort. The approximation yields a number of analytic predictions, including a "gain-clamping" transition at which strong modal interactions suppress all higher modes. We show that the single-pole approximation agrees well with exact SALT calculations, particularly for high-Q cavities. Within this range of validity, it provides an extraordinarily efficient technique for modeling realistic and complex lasers.Comment: 17 pages, 11 figure

Among-site variability in the stochastic dynamics of East African coral reefs

Coral reefs are dynamic systems whose composition is highly influenced by unpredictable biotic and abiotic factors. Understanding the spatial scale at which long-term predictions of reef composition can be made will be crucial for guiding conservation efforts. Using a 22-year time series of benthic composition data from 20 reefs on the Kenyan and Tanzanian coast, we studied the long-term behaviour of Bayesian vector autoregressive state-space models for reef dynamics, incorporating among-site variability. We estimate that if there were no among-site variability, the total long-term variability would be approximately one third of its current value. Thus among-site variability contributes more to long-term variability in reef composition than does temporal variability. Individual sites are more predictable than previously thought, and predictions based on current snapshots are informative about long-term properties. Our approach allowed us to identify a subset of possible climate refugia sites with high conservation value, where the long-term probability of coral cover <= 0.1 was very low. Analytical results show that this probability is most strongly influenced by among-site variability and by interactions among benthic components within sites. These findings suggest that conservation initiatives might be successful at the site scale as well as the regional scale.Comment: 97 pages, 49 figure

Alternate proof of the Rowe-Rosensteel proposition and seniority conservation

For a system with three identical nucleons in a single-$j$ shell, the states can be written as the angular momentum coupling of a nucleon pair and the odd nucleon. The overlaps between these non-orthonormal states form a matrix which coincides with the one derived by Rowe and Rosensteel [Phys. Rev. Lett. {\bf 87}, 172501 (2001)]. The propositions they state are related to the eigenvalue problems of the matrix and dimensions of the associated subspaces. In this work, the propositions will be proven from the symmetric properties of the $6j$ symbols. Algebraic expressions for the dimension of the states, eigenenergies as well as conditions for conservation of seniority can be derived from the matrix.Comment: 9 pages, no figur

Comparative effects of castration and dehorning in series or concurrent castration and dehorning procedures on stress responses and production in Holstein calves

The study objective was to compare serum cortisol as an acute stress measure, chute exit velocity as a behavioral measure, and ADG as an indicator of performance and well-being after castration, dehorning, or concurrent castration/dehorning of calves when performed in parallel and in series. Intact male Holstein calves, 3 to 4 mo, underwent sham handling before 2 procedures performed in series separated by 2 to 3 wk. In Period 1, calves were either dehorned by amputation, surgically castrated, concurrently castrated/dehorned, or served as nonsurgical controls (n = 10/treatment). In Period 2, calves that had been dehorned, castrated, or castrated/dehorned were then castrated, dehorned, or served as nonsurgical controls, respectively. Indicators of distress were measured after all procedures; ADG was assessed for 7 d after each procedure and over the 2 to 3 wk interim. Period 1 cortisol concentrations in dehorned calves were less than in castrated and castrated/dehorned calves at 120 min and from 50 to 240 min, respectively (P \u3c 0.02). There was marginal evidence that cortisol concentrations were greater in castrated/dehorned than castrated calves at 60 min (P = 0.06). Period 2 cortisol concentrations were less in dehorned than castrated calves at 120 min (P = 0.005) but were greater from 360 to 480 min (P \u3c 0.002). The Period 2 cortisol profile of control calves did not differ from the baseline obtained during sham handling, despite the intervening castration/dehorning in Period 1, suggesting that memory did not affect cortisol. The cortisol profile of castrated calves did not differ between periods except at 720 min, when Period 1 concentrations were greater than Period 2 (P = 0.02). Cortisol concentrations of calves dehorned in Period 2 were greater than those dehorned in Period 1 at 20 and 240 to 480 min (P \u3c 0.05). In both periods, castrated calves exited the chute slower than dehorned calves (P \u3c 0.05). The ADG did not differ between surgically treated calves in Period 1; in the interim, the ADG of castrated calves was greater than that of castrated/dehorned calves (difference ± SED, 1.4 ± 0.6 kg/d; P = 0.03), and in Period 2, the ADG of dehorned calves was less than castrated calves (1.8 ± 0.6 kg/d; P = 0.005). Our study supports both the common practice of concurrent castration/dehorning and the sequence of dehorning and castration. Delayed dehorning (vs. delayed castration) appeared to be more acutely stressful and more detrimental to ADG

Nanoscopic coexistence of magnetic and superconducting states within the FeAs layers of CeFeAsO1-xFx

We report on the coexistence of magnetic and superconducting states in CeFeAsO1-xFx for x=0.06(2), characterized by transition temperatures T_m=30 K and T_c=18 K, respectively. Zero and transverse field muon-spin relaxation measurements show that below 10 K the two phases coexist within a nanoscopic scale over a large volume fraction. This result clarifies the nature of the magnetic-to-superconducting transition in the CeFeAsO1-xFx phase diagram, by ruling out the presence of a quantum critical point which was suggested by earlier studies.Comment: 4 pages, 3 figs, accepted for publication as PRB Rapid com