The Allometry of Daily Energy Expenditure in Hummingbirds: An Energy Budget Approach

1. Within-clade allometric relationships represent standard laws of scaling between energy and size, and their outliers provide new avenues for physiological and ecological research. According to the metabolic-level boundaries hypothesis, metabolic rates as a function of mass are expected to scale closer to 0.67 when driven by surface-related processes (e.g. heat or water flux), while volume-related processes (e.g. activity) generate slopes closer to one. 2. In birds, daily energy expenditure (DEE) scales with body mass (M) in the relationship log (DEE)=2.35+0.68×log (M), consistent with surface-level processes driving the relationship. However, taxon-specific patterns differ from the scaling slope of all birds. 3. Hummingbirds have the highest mass-specific metabolic rates among all vertebrates. Previous studies on a few hummingbird species, without accounting for the phylogeny, estimated that the DEE–body mass relationship for hummingbirds was log (DEE)=1.72+1.21×log (M). In Contrast to the theoretical expectations, this slope \u3e1 indicates that larger hummingbirds are less metabolically efficient than smaller hummingbirds. 4. We collected DEE and mass data for 12 hummingbird species, which, combined with published data, represented 17 hummingbird species in eight of nine hummingbird clades over a sixfold size range of body size (2.7–17.5 g). 5. After accounting for phylogenetic relatedness, we found DEE scales with body mass as log(DEE)=2.04+0.95×log (M). This slope of 0.95 is lower than previously estimated for hummingbirds, but much higher than the slope for all birds (0.68). The high slopes of torpor, hovering and flight potentially explain the high interspecific DEE slope for hummingbirds compared to other endotherms

A Review of Network and Computer Analysis of Epileptiform Discharge Free EEG to Characterize and Detect Epilepsy.

Objectives. There is emerging evidence that network/computer analysis of epileptiform discharge free electroencephalograms (EEGs) can be used to detect epilepsy, improve diagnosis and resource use. Such methods are automated and can be performed on shorter recordings of EEG. We assess the evidence and its strength in the area of seizure detection from network/computer analysis of epileptiform discharge free EEG. Methods. A scoping review using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidance was conducted with a literature search of Embase, Medline and PsychINFO. Predesigned inclusion/exclusion criteria were applied to selected articles. Results. The initial search found 3398 articles. After duplicate removal and screening, 591 abstracts were reviewed, 64 articles were selected and read leading to 20 articles meeting the requisite inclusion/exclusion criteria. These were 9 reports and 2 cross-sectional studies using network analysis to compare and/or classify EEG. One review of 17 reports and 10 cross-sectional studies only aimed to classify the EEGs. One cross-sectional study discussed EEG abnormalities associated with autism. Conclusions. Epileptiform discharge free EEG features derived from network/computer analysis differ significantly between people with and without epilepsy. Diagnostic algorithms report high accuracies and could be clinically useful. There is a lack of such research within the intellectual disability (ID) and/or autism populations, where epilepsy is more prevalent and there are additional diagnostic challenges

Dynamical Correlations in a Half-Filled Landau Level

We formulate a self-consistent field theory for the Chern-Simons fermions to study the dynamical response function of the quantum Hall system at $\nu=1/2$. Our scheme includes the effect of correlations beyond the random-phase approximation (RPA) employed to this date for this system. The resulting zero-frequency density response function vanishes as the square of the wave vector in the long-wavelength limit. The longitudinal conductivity calculated in this scheme shows linear dependence on the wave vector, like the experimentals results and the RPA, but the absolute values are higher than the experimental results.Comment: 4 pages, revtex, 3 figures included. Corrected typo

Correlators and fractional statistics in the quantum Hall bulk

We derive single-particle and two-particle correlators of anyons in the presence of a magnetic field in the lowest Landau level. We show that the two-particle correlator exhibits signatures of fractional statistics which can distinguish anyons from their fermionic and bosonic counterparts. These signatures include the zeroes of the two-particle correlator and its exclusion behavior. We find that the single-particle correlator in finite geometries carries valuable information relevant to experiments in which quasiparticles on the edge of a quantum Hall system tunnel through its bulk.Comment: 4 pages, 3 figures, RevTe

SARAS 2: A Spectral Radiometer for probing Cosmic Dawn and the Epoch of Reionization through detection of the global 21 cm signal

The global 21 cm signal from Cosmic Dawn (CD) and the Epoch of Reionization (EoR), at redshifts $z \sim 6-30$, probes the nature of first sources of radiation as well as physics of the Inter-Galactic Medium (IGM). Given that the signal is predicted to be extremely weak, of wide fractional bandwidth, and lies in a frequency range that is dominated by Galactic and Extragalactic foregrounds as well as Radio Frequency Interference, detection of the signal is a daunting task. Critical to the experiment is the manner in which the sky signal is represented through the instrument. It is of utmost importance to design a system whose spectral bandpass and additive spurious can be well calibrated and any calibration residual does not mimic the signal. SARAS is an ongoing experiment that aims to detect the global 21 cm signal. Here we present the design philosophy of the SARAS 2 system and discuss its performance and limitations based on laboratory and field measurements. Laboratory tests with the antenna replaced with a variety of terminations, including a network model for the antenna impedance, show that the gain calibration and modeling of internal additives leave no residuals with Fourier amplitudes exceeding 2~mK, or residual Gaussians of 25 MHz width with amplitudes exceeding 2~mK. Thus, even accounting for reflection and radiation efficiency losses in the antenna, the SARAS~2 system is capable of detection of complex 21-cm profiles at the level predicted by currently favoured models for thermal baryon evolution.Comment: 44 pages, 17 figures; comments and suggestions are welcom

A systems analysis and conceptual system dynamics model of the livestock-derived food system in South Africa : a tool for policy guidance

Global food production systems are currently under scrutiny, in particular the health, nutrition, and environmental impacts of livestock-derived food (LDF). Despite South Africa’s recent socio­economic transformation and increased per-capita LDF consumption, the triple burden of malnutri­tion persists. Policy responses to such complex problems often fail because of linear thinking with short-term goals. However, a systems approach helps identify root causes, feedback mechanisms, potential unintended consequences, and opportu­nities for integrated, durable solutions. Participa­tion in the systems-thinking process improves stakeholder understanding and buy-in. Our par­ticipatory workshop facilitated the development of a systems map for South African LDF, identifying key system elements, linkages, and nexus points. The latter included climate change, land access and management, livestock management and produc­tivity, farming systems, food safety, policy articula­tion, agricultural knowledge, and income. Based on these findings, and an overview of related litera­ture, we produced a conceptual system dynamics model of the LDF system. We identified key vari­ables and causal relationships, vicious and virtuous loops, system archetypes, conceptual stock and flows, and links to Sustainable Development Goals. The LDF system is complex and dynamic, with a dominance of commercial enterprises across agriculture and food retail, presenting barriers for small and medium-scale individuals. Other key elements relate to population growth and urbaniza­tion, land access, deregulation of international trade, climate change vulnerability, feed production limitations, and food safety. Our work provides a unique reference for policymakers, identifying the need for deep structural change, highlighting the possible unintended consequences, and thereby mitigating the risk of system destabilization

A Deeper Look at Student Learning of Quantum Mechanics: the Case of Tunneling

We report on a large-scale study of student learning of quantum tunneling in 4 traditional and 4 transformed modern physics courses. In the transformed courses, which were designed to address student difficulties found in previous research, students still struggle with many of the same issues found in other courses. However, the reasons for these difficulties are more subtle, and many new issues are brought to the surface. By explicitly addressing how to build models of wave functions and energy and how to relate these models to real physical systems, we have opened up a floodgate of deep and difficult questions as students struggle to make sense of these models. We conclude that the difficulties found in previous research are the tip of the iceberg, and the real issue at the heart of student difficulties in learning quantum tunneling is the struggle to build the complex models that are implicit in experts' understanding but often not explicitly addressed in instruction.Comment: v2, v3 updated with more detailed analysis of data and discussion; submitted to Phys. Rev. ST: PE

Waveform Design for 4D-Imaging mmWave PMCW MIMO Radars with Spectrum Compatibility

4D-imaging mmWave radars offer high angular resolution in both azimuth and elevation, but achieving this requires a large antenna aperture size and a significant number of transmit and/or receive channels. This presents a challenge for designing transmit waveforms that are both orthogonal and separable on the receive side, as well as have low auto-correlation sidelobes. This paper focuses on designing an orthogonal set of sequences for 4D-imaging radar sensors based on PMCW technology. We propose an iterative optimization framework based on Coordinate Descent, which considers the Regions Of Interest (ROI) and optimizes a phase-modulated constant modulus waveform set based on weighted integrated sidelobe level on the required ROI and spectrum shaping. The optimization also accounts for the radar working adjacent to communication systems and other radar sensors. Simulation results are provided to demonstrate the effectiveness of the proposed method, which achieves low sidelobe levels and is compatible with spectrum constraints

Renormalization Group Approach to Strong-Coupled Superconductors

We develop an asymptotically exact renormalization group (RG) approach that treats electron-electron and electron-phonon interactions on equal footing. The approach allows an unbiased study of the instabilities of Fermi liquids without the assumption of a broken symmetry. We apply our method to the problem of strongly coupled superconductors and find the temperature T* below which the high-temperature Fermi liquid state becomes unstable towards Cooper pairing. We show that T* is the same as the critical temperature Tc obtained in Eliashberg's strong coupling theory starting from the low-temperature superconducting phase. We also show that Migdal's theorem is implicit in our approach. Finally, our results lead to a novel way to calculate numerically, from microscopic parameters, the transition temperature of superconductors.Comment: 6 pages, 3 figures, expanded presentation, final versio