Stably accessing octave-spanning microresonator frequency combs in the soliton regime

Microresonator frequency combs can be an enabling technology for optical frequency synthesis and timekeeping in low size, weight, and power architectures. Such systems require comb operation in low-noise, phase-coherent states such as solitons, with broad spectral bandwidths (e.g., octave-spanning) for self-referencing to detect the carrier-envelope offset frequency. However, stably accessing such states is complicated by thermo-optic dispersion. For example, in the Si3N4 platform, precisely dispersion-engineered structures can support broadband operation, but microsecond thermal time constants have necessitated fast pump power or frequency control to stabilize the solitons. In contrast, here we consider how broadband soliton states can be accessed with simple pump laser frequency tuning, at a rate much slower than the thermal dynamics. We demonstrate octave-spanning soliton frequency combs in Si3N4 microresonators, including the generation of a multi-soliton state with a pump power near 40 mW and a single-soliton state with a pump power near 120 mW. We also develop a simplified two-step analysis to explain how these states are accessed in a thermally stable way without fast control of the pump laser, and outline the required thermal properties for such operation. Our model agrees with experimental results as well as numerical simulations based on a Lugiato-Lefever equation that incorporates thermo-optic dispersion. Moreover, it also explains an experimental observation that a member of an adjacent mode family on the red-detuned side of the pump mode can mitigate the thermal requirements for accessing soliton states

Cerebellar modulation of memory encoding in the periaqueductal grey and fear behaviour

The pivotal role of the periaqueductal grey (PAG) in fear learning is reinforced by the identification of neurons in male rat ventrolateral PAG (vlPAG) that encode fear memory through signalling the onset and offset of an auditory-conditioned stimulus during presentation of the unreinforced conditioned tone (CS+) during retrieval. Some units only display CS+ onset or offset responses, and the two signals differ in extinction sensitivity, suggesting that they are independent of each other. In addition, understanding cerebellar contributions to survival circuits is advanced by the discovery that (i) reversible inactivation of the medial cerebellar nucleus (MCN) during fear consolidation leads in subsequent retrieval to (a) disruption of the temporal precision of vlPAG offset, but not onset responses to CS+, and (b) an increase in duration of freezing behaviour. And (ii) chemogenetic manipulation of the MCN-vlPAG projection during fear acquisition (a) reduces the occurrence of fear-related ultrasonic vocalisations, and (b) during subsequent retrieval, slows the extinction rate of fear-related freezing. These findings show that the cerebellum is part of the survival network that regulates fear memory processes at multiple timescales and in multiple ways, raising the possibility that dysfunctional interactions in the cerebellar-survival network may underlie fear-related disorders and comorbidities

Book Reviews

If there is a living American qualified to prepare material for the student of future interests probably law teachers would agree that Professor Kales is the man. He has written a book on Future Estates in Illinois which has made a distinct impression on the law of that state and is recognized elsewhere as a sound and scholarly treatise. He has taught the course on future interests and illegal restraints at Northwestern University Law School for many years, and last year gave the same course at Harvard

Modeling the Low State Spectrum of the X-Ray Nova XTE J1118+480

Based on recent multiwavelength observations of the new X-ray nova XTE J1118+480, we can place strong constraints on the geometry of the accretion flow in which a low/hard state spectrum, characteristic of an accreting black hole binary, is produced. We argue that the absence of any soft blackbody-like component in the X-ray band implies the existence of an extended hot optically-thin region, with the optically-thick cool disk truncated at some radius R_{tr} > 55 R_{Schw}. We show that such a model can indeed reproduce the main features of the observed spectrum: the relatively high optical to X-ray ratio, the sharp downturn in the far UV band and the hard X-ray spectrum. The absence of the disk blackbody component also underscores the requirement that the seed photons for thermal Comptonization be produced locally in the hot flow, e.g. via synchrotron radiation. We attribute the observed spectral break at 2 keV to absorption in a warm, partially ionized gas.Comment: 6 pages, including 1 figure; LaTeX (emulateapj5.sty), to appear in Ap

Comparing Survival Rates and Mortality in Operative Versus Nonoperative Treatment For Femoral Neck Fractures among alzheimer\u27s Disease Patients: a Retrospective Cohort Study

INTRODUCTION: Addressing femoral neck fractures resulting from ground-level falls in older adults with Alzheimer\u27s disease (AD) involves a personalized treatment plan. There is considerable ongoing debate concerning the relative advantages and disadvantages of surgical treatment (internal fixation or arthroplasty) vs nonoperative treatment for femoral neck fractures in older persons with AD. METHODS: This retrospective cohort study compared the mortality, hazard ratio, and survival rate between operative and nonoperative treatments, controlling for patients\u27 demographic information and baseline health status. The study population consisted of Optum beneficiaries diagnosed with AD who experienced an initial femoral neck fracture claim between January 1, 2012, and December 31, 2017. Kaplan-Meier survival curves were applied to compare the treatment groups\u27 post-fracture survival rates and mortality. Cox regression was used to examine the survival period by controlling the covariates. RESULTS: Out of the 4157 patients with AD with femoral neck fractures, 59.8% were women (n = 2487). The median age was 81 years. The 1-year survival rate for nonoperative treatment (70.19%) was lower than that for internal fixation (75.27%) and arthroplasty treatment (82.32%). Compared with the nonoperative group, arthroplasty surgical treatment had significant lower hazard risk of death (arthroplasty hazard ratio: 0.850, 95% CI: 0.728-0.991, DISCUSSION: The findings suggest that the operative treatment group experiences higher survival rates and lower mortality rates than the nonoperative group. This paper provides insights into treatment outcomes of older adults with AD receiving medical care for femoral neck fractures

The Family Psychoeducation Fidelity Scale: Psychometric Properties

This study examined psychometric properties and feasibility of the Family Psychoeducation (FPE) Fidelity Scale. Fidelity assessors conducted reviews using the FPE fidelity scale four times over 18 months at five sites in Norway. After completing fidelity reviews, assessors rated feasibility of the fidelity review process. The FPE fidelity scale showed excellent interrater reliability (.99), interrater item agreement (88%), and internal consistency (mean = .84 across four time points). By the 18-month follow-up, all five sites increased fidelity and three reached adequate fidelity. Fidelity assessors rated feasibility as excellent. The FPE fidelity scale has good psychometric properties and is feasible for evaluating the implementation of FPE programs. Trial registration ClinicalTrials.gov Identifier: NCT03271242.publishedVersio

Comparing Survival Rates and Mortality in Operative Versus Nonoperative Treatment for Femoral Neck Fractures Among Alzheimer\u27s Disease Patients: A Retrospective Cohort Study

INTRODUCTION: Addressing femoral neck fractures resulting from ground-level falls in older adults with Alzheimer\u27s disease (AD) involves a personalized treatment plan. There is considerable ongoing debate concerning the relative advantages and disadvantages of surgical treatment (internal fixation or arthroplasty) vs nonoperative treatment for femoral neck fractures in older persons with AD. METHODS: This retrospective cohort study compared the mortality, hazard ratio, and survival rate between operative and nonoperative treatments, controlling for patients\u27 demographic information and baseline health status. The study population consisted of Optum beneficiaries diagnosed with AD who experienced an initial femoral neck fracture claim between January 1, 2012, and December 31, 2017. Kaplan-Meier survival curves were applied to compare the treatment groups\u27 post-fracture survival rates and mortality. Cox regression was used to examine the survival period by controlling the covariates. RESULTS: Out of the 4157 patients with AD with femoral neck fractures, 59.8% were women (n = 2487). The median age was 81 years. The 1-year survival rate for nonoperative treatment (70.19%) was lower than that for internal fixation (75.27%) and arthroplasty treatment (82.32%). Compared with the nonoperative group, arthroplasty surgical treatment had significant lower hazard risk of death (arthroplasty hazard ratio: 0.850, 95% CI: 0.728-0.991, DISCUSSION: The findings suggest that the operative treatment group experiences higher survival rates and lower mortality rates than the nonoperative group. This paper provides insights into treatment outcomes of older adults with AD receiving medical care for femoral neck fractures

The accuracies of DNA-based estimates of genetic merit derived from Angus or multibreed beef cattle training populations

Several organizations have developed prediction models for molecular breeding values (MBV) for quantitative growth and carcass traits in beef cattle using Bovine SNP50 genotypes and phenotypic or EBV data. Molecular breeding values for Angus cattle have been developed by IGENITY, Pfi zer Animal Genetics, and a collaboration between researchers from Iowa State University and the University of Missouri-Columbia (ISU/UMC). The U.S. Meat Animal Research Center (USMARC; Clay Center, NE) has also developed MBV for 16 cattle breeds using 2 multibreed populations, the Germplasm Evaluation (GPE) Program and the 2,000 Bull Project (2KALL), and 2 single breed subpopulations of the 2,000 Bull Project, Angus (2KAN) and Hereford (2KHH). In this study, these MBV were assessed relative to commercial ranch EBV estimated from the progeny phenotypes of Angus bulls naturally mated in multisire breeding pastures to commercial cows: 121 for USMARC MBV, 99 for ISU/UMC MBV, and 29 for IGENITY and Pfizer MBV (selected based on number of progeny carcass records). Five traits were analyzed: weaning weight (WW), HCW, marbling score (MS), rib-eye muscle area (RE), and, for IGENITY and Pfi zer only, feedlot ADG. The average accuracies of MBV across traits were 0.38 ± 0.05 for IGENITY, 0.61 ± 0.12 for Pfizer, 0.46 ± 0.12 for ISU/UMC, 0.16 ± 0.04 for GPE, 0.26 ± 0.05 for 2KALL, 0.24 ± 0.04 for 2KAN, and 0.02 ± 0.12 for 2KHH. Angus-based MBV (IGENITY, Pfizer, ISU/UMC, and 2KAN) explained larger proportions of genetic variance in this population than GPE, 2KALL, or 2KHH MBV for the same traits. In this data set, IGENITY, Pfizer, and ISU/UMC MBV were predictive of realized performance of progeny, and incorporation of that information into national genetic evaluations would be expected to improve EPD accuracy, particularly for young animals