Validation of CTmax Protocols Using Cased and Uncased \u3ci\u3ePycnopsyche Guttifer\u3c/i\u3e (Trichoptera: Limnephilidae) Larvae

The critical thermal maximum (CTmax) of a northern Lower Michigan population of Pycnopsyche guttifer was determined using four rates of temperature increase (0.10, 0.33, 0.50, and 0.70oC per minute), and two case states (intact and removed). Across all temperature increase rates, larvae removed from their cases had a significantly lower mean CTmax than those remaining in their cases, suggesting that the case can increase the larva’s ability to tolerate thermal stress, possibly due to respiratory advantages. Regardless of case state, mean CTmax was significantly lower at the 0.10oC per minute increase rate than the other three rates, likely due to increased exposure time. Our results indicate that CTmax studies done using 0.33–0.70oC per minute increase protocols would be comparable with each other, but not with studies using an increase rate of 0.10oC per minute

China Maritime Report No. 33: China\u27s Sea-Based Nuclear Deterrent: Organizational, Operational, and Strategic Implications

China’s development of a credible sea-based deterrent has important implications for the PLAN, for China’s nuclear strategy, and for U.S.-China strategic stability. For the PLAN, the need to protect the SSBN force may divert resources away from other missions; it may also provide justification for further expansion of the PLAN fleet size. For China’s nuclear strategy and operations, the SSBN force may increase operational and bureaucratic pressures for adopting a more forward-leaning nuclear strategy. For U.S.-China strategic stability, the SSBN force will have complex effects, decreasing risks that Chinese decisionmakers confront use-or-lose escalation pressures, making China less susceptible to U.S. nuclear threats and intimidation and therefore perceiving lower costs to conventional aggression, and potentially introducing escalation risks from conventional-nuclear entanglement to the maritime domain.https://digital-commons.usnwc.edu/cmsi-maritime-reports/1032/thumbnail.jp

Two-channel Kondo physics in two-impurity Kondo models

We consider the non-Fermi liquid quantum critical state of the spin-S two-impurity Kondo model, and its potential realization in a quantum dot device. Using conformal field theory (CFT) and the numerical renormalization group (NRG), we show the critical point to be identical to that of the two-channel Kondo model with additional potential scattering, for any spin-S. Distinct conductance signatures are shown to arise as a function of device asymmetry; with the `smoking gun' square-root behavior, commonly believed to arise at low-energies, dominant only in certain regimes.Comment: 4.5 pages (with 3 figures) + 9 pages (with 4 figures) supplementary materia

Single-particle dynamics of the Anderson model: a two-self-energy description within the numerical renormalization group approach

Single-particle dynamics of the Anderson impurity model are studied using both the numerical renormalization group (NRG) method and the local moment approach (LMA). It is shown that a 'two-self-energy' description of dynamics inherent to the LMA, as well as a conventional 'single-self-energy' description, arise within NRG; each yielding correctly the same local single-particle spectrum. Explicit NRG results are obtained for the broken symmetry spectral constituents arising in a two-self-energy description, and the total spectrum. These are also compared to analytical results obtained from the LMA as implemented in practice. Very good agreement between the two is found, essentially on all relevant energy scales from the high-energy Hubbard satellites to the low-energy Kondo resonance.Comment: 12 pages, 6 figure

Dynamics of capacitively coupled double quantum dots

We consider a double dot system of equivalent, capacitively coupled semiconducting quantum dots, each coupled to its own lead, in a regime where there are two electrons on the double dot. Employing the numerical renormalization group, we focus here on single-particle dynamics and the zero-bias conductance, considering in particular the rich range of behaviour arising as the interdot coupling is progressively increased through the strong coupling (SC) phase, from the spin-Kondo regime, across the SU(4) point to the charge-Kondo regime; and then towards and through the quantum phase transition to a charge-ordered (CO) phase. We first consider the two-self-energy description required to describe the broken symmetry CO phase, and implications thereof for the non-Fermi liquid nature of this phase. Numerical results for single-particle dynamics on all frequency scales are then considered, with particular emphasis on universality and scaling of low-energy dynamics throughout the SC phase. The role of symmetry breaking perturbations is also briefly discussed.Comment: 14 pages, 6 figure

Validation of CTmax Protocols Using Cased and Uncased \u3ci\u3ePycnopsyche Guttifer\u3c/i\u3e (Trichoptera: Limnephilidae) Larvae

The critical thermal maximum (CTmax) of a northern Lower Michigan population of Pycnopsyche guttifer was determined using four rates of temperature increase (0.10, 0.33, 0.50, and 0.70oC per minute), and two case states (intact and removed). Across all temperature increase rates, larvae removed from their cases had a significantly lower mean CTmax than those remaining in their cases, suggesting that the case can increase the larva’s ability to tolerate thermal stress, possibly due to respiratory advantages. Regardless of case state, mean CTmax was significantly lower at the 0.10oC per minute increase rate than the other three rates, likely due to increased exposure time. Our results indicate that CTmax studies done using 0.33–0.70oC per minute increase protocols would be comparable with each other, but not with studies using an increase rate of 0.10oC per minute

Finite temperature dynamics of the Anderson model

The recently introduced local moment approach (LMA) is extended to encompass single-particle dynamics and transport properties of the Anderson impurity model at finite-temperature, T. While applicable to arbitrary interaction strengths, primary emphasis is given to the strongly correlated Kondo regime (characterized by the T=0 Kondo scale $\omega_{\rm K}$). In particular the resultant universal scaling behaviour of the single-particle spectrum D(\omega; T) \equiv F(\frac{\w}{\omega_{\rm K}}; \frac{T}{\omega_{\rm K}}) within the LMA is obtained in closed form; leading to an analytical description of the thermal destruction of the Kondo resonance on all energy scales. Transport properties follow directly from a knowledge of $D(\omega; T)$. The $T / \omega_{\rm K}$-dependence of the resulting resistivity $\rho(T)$, which is found to agree rather well with numerical renormalization group calculations, is shown to be asymptotically exact at high temperatures; to concur well with the Hamann approximation for the s-d model down to $T/\omega_{\rm K} \sim 1$, and to cross over smoothly to the Fermi liquid form $\rho (T) - \rho (0) \propto -(T/\omega_{\rm K})^2$ in the low-temperature limit. The underlying approach, while naturally approximate, is moreover applicable to a broad range of quantum impurity and related models

Zero-bias conductance in carbon nanotube quantum dots

We present numerical renormalization group calculations for the zero-bias conductance of quantum dots made from semiconducting carbon nanotubes. These explain and reproduce the thermal evolution of the conductance for different groups of orbitals, as the dot-lead tunnel coupling is varied and the system evolves from correlated Kondo behavior to more weakly correlated regimes. For integer fillings $N=1,2,3$ of an SU(4) model, we find universal scaling behavior of the conductance that is distinct from the standard SU(2) universal conductance, and concurs quantitatively with experiment. Our results also agree qualitatively with experimental differential conductance maps.Comment: 4 pages, 5 figure

Anderson impurity in a semiconductor

We consider an Anderson impurity model in which the locally correlated orbital is coupled to a host with a gapped density of states. Single-particle dynamics are studied, within a perturbative framework that includes both explicit second-order perturbation theory and self-consistent perturbation theory to all orders in the interaction. Away from particle-hole symmetry the system is shown to be a generalized Fermi liquid (GFL) in the sense of being perturbatively connectable to the non-interacting limit; and the exact Friedel sum rule for the GFL phase is obtained. We show by contrast that the particle-hole symmetric point of the model is not perturbatively connected to the non-interacting limit, and as such is a non-Fermi liquid for all non-zero gaps. Our conclusions are in agreement with NRG studies of the problem.Comment: 7 pages, 4 figure

Single-particle dynamics of the Anderson model: a local moment approach

A non-perturbative local moment approach to single-particle dynamics of the general asymmetric Anderson impurity model is developed. The approach encompasses all energy scales and interaction strengths. It captures thereby strong coupling Kondo behaviour, including the resultant universal scaling behaviour of the single-particle spectrum; as well as the mixed valent and essentially perturbative empty orbital regimes. The underlying approach is physically transparent and innately simple, and as such is capable of practical extension to lattice-based models within the framework of dynamical mean-field theory.Comment: 26 pages, 9 figure