First Observation of Cyclotron Radiation from MeV-Scale e

We present an apparatus for detection of cyclotron radiation yielding a frequency-based ß^{±} kinetic energy determination in the 5 keV to 2.1 MeV range, characteristic of nuclear ß decays. The cyclotron frequency of the radiating ß particles in a magnetic field is used to determine the ß energy precisely. Our work establishes the foundation to apply the cyclotron radiation emission spectroscopy (CRES) technique, developed by the Project 8 Collaboration, far beyond the 18-keV tritium endpoint region. We report initial measurements of ß^{-}'s from ^{6}He and ß^{+}'s from ^{19}Ne decays to demonstrate the broadband response of our detection system and assess potential systematic uncertainties for ß spectroscopy over the full (MeV) energy range. To our knowledge, this is the first direct observation of cyclotron radiation from individual highly relativistic ß's in a waveguide. This work establishes the application of CRES to a variety of nuclei, opening its reach to searches for new physics beyond the TeV scale via precision ß-decay measurements.

Tritium Beta Spectrum Measurement and Neutrino Mass Limit from Cyclotron Radiation Emission Spectroscopy.

The absolute scale of the neutrino mass plays a critical role in physics at every scale, from the subatomic to the cosmological. Measurements of the tritium end-point spectrum have provided the most precise direct limit on the neutrino mass scale. In this Letter, we present advances by Project 8 to the cyclotron radiation emission spectroscopy (CRES) technique culminating in the first frequency-based neutrino mass limit. With only a cm^{3}-scale physical detection volume, a limit of m_{ß}<155 eV/c^{2} (152 eV/c^{2}) is extracted from the background-free measurement of the continuous tritium beta spectrum in a Bayesian (frequentist) analysis. Using ^{83m}Kr calibration data, a resolution of 1.66±0.19 eV (FWHM) is measured, the detector response model is validated, and the efficiency is characterized over the multi-keV tritium analysis window. These measurements establish the potential of CRES for a high-sensitivity next-generation direct neutrino mass experiment featuring low background and high resolution.

Axion Dark Matter Experiment: Detailed design and operations.

Axion dark matter experiment ultra-low noise haloscope technology has enabled the successful completion of two science runs (1A and 1B) that looked for dark matter axions in the 2.66-3.1 µeV mass range with Dine-Fischler-Srednicki-Zhitnisky sensitivity [Du et al., Phys. Rev. Lett. 120, 151301 (2018) and Braine et al., Phys. Rev. Lett. 124, 101303 (2020)]. Therefore, it is the most sensitive axion search experiment to date in this mass range. We discuss the technological advances made in the last several years to achieve this sensitivity, which includes the implementation of components, such as the state-of-the-art quantum-noise-limited amplifiers and a dilution refrigerator. Furthermore, we demonstrate the use of a frequency tunable microstrip superconducting quantum interference device amplifier in run 1A, and a Josephson parametric amplifier in run 1B, along with novel analysis tools that characterize the system noise temperature.

Heritable variation in heat shock gene expression: a potential mechanism for adaptation to thermal stress in embryos of sea turtles.

The capacity of species to respond adaptively to warming temperatures will be key to their survival in the Anthropocene. The embryos of egg-laying species such as sea turtles have limited behavioural means for avoiding high nest temperatures, and responses at the physiological level may be critical to coping with predicted global temperature increases. Using the loggerhead sea turtle (Caretta caretta) as a model, we used quantitative PCR to characterise variation in the expression response of heat-shock genes (hsp60, hsp70 and hsp90; molecular chaperones involved in cellular stress response) to an acute non-lethal heat shock. We show significant variation in gene expression at the clutch and population levels for some, but not all hsp genes. Using pedigree information, we estimated heritabilities of the expression response of hsp genes to heat shock and demonstrated both maternal and additive genetic effects. This is the first evidence that the heat-shock response is heritable in sea turtles and operates at the embryonic stage in any reptile. The presence of heritable variation in the expression of key thermotolerance genes is necessary for sea turtles to adapt at a molecular level to warming incubation environments.

Single-Electron Detection and Spectroscopy via Relativistic Cyclotron Radiation.

It has been understood since 1897 that accelerating charges must emit electromagnetic radiation. Although first derived in 1904, cyclotron radiation from a single electron orbiting in a magnetic field has never been observed directly. We demonstrate single-electron detection in a novel radio-frequency spectrometer. The relativistic shift in the cyclotron frequency permits a precise electron energy measurement. Precise beta electron spectroscopy from gaseous radiation sources is a key technique in modern efforts to measure the neutrino mass via the tritium decay end point, and this work demonstrates a fundamentally new approach to precision beta spectroscopy for future neutrino mass experiments.

Increased expression of Hsp70 and Hsp90 mRNA as biomarkers of thermal stress in loggerhead turtle embryos (Caretta Caretta).

The survival and viability of sea turtle embryos is dependent upon favourable nest temperatures throughout the incubation period. Consequently, future generations of sea turtles may be at risk from increasing nest temperatures due to climate change, but little is known about how embryos respond to heat stress. Heat shock genes are likely to be important in this process because they code for proteins that prevent cellular damage in response to environmental stressors. This study provides the first evidence of an expression response in the heat shock genes of embryos of loggerhead sea turtles (Caretta caretta) exposed to realistic and near-lethal temperatures (34°C and 36°C) for 1 or 3 hours. We investigated changes in Heat shock protein 60 (Hsp60), Hsp70, and Hsp90 mRNA in heart (n=24) and brain tissue (n=29) in response to heat stress. Under the most extreme treatment (36°C, 3h), Hsp70 increased mRNA expression by a factor of 38.8 in heart tissue and 15.7 in brain tissue, while Hsp90 mRNA expression increased by a factor of 98.3 in heart tissue and 14.7 in brain tissue. Hence, both Hsp70 and Hsp90 are useful biomarkers for assessing heat stress in the late-stage embryos of sea turtles. The method we developed can be used as a platform for future studies on variation in the thermotolerance response from the clutch to population scale, and can help us anticipate the resilience of reptile embryos to extreme heating events.

The CTFA Evaluation of Alternatives Program: an evaluation of in vitro alternatives to the Draize primary eye irritation test. (Phase III) surfactant-based formulations.

The CTFA Evaluation of Alternatives Program is an evaluation of the relationship between data from the Draize primary eye irritation test and comparable data from a selection of promising in vitro eye irritation tests. In Phase III, data from the Draize test and 41 in vitro endpoints on 25 representative surfactant-based personal care formulations were compared. As in Phase I and Phase II, regression modelling of the relationship between maximum average Draize score (MAS) and in vitro endpoint was the primary approach adopted for evaluating in vitro assay performance. The degree of confidence in prediction of MAS for a given in vitro endpoint is quantified in terms of the relative widths of prediction intervals constructed about the fitted regression curve. Prediction intervals reflect not only the error attributed to the model but also the material-specific components of variation in both the Draize and the in vitro assays. Among the in vitro assays selected for regression modeling in Phase III, the relationship between MAS and in vitro score was relatively well defined. The prediction bounds on MAS were most narrow for materials at the lower or upper end of the effective irritation range (MAS = 0-45), where variability in MAS was smallest. This, the confidence with which the MAS of surfactant-based formulations is predicted is greatest when MAS approaches zero or when MAS approaches 45 (no comment is made on prediction of MAS > 45 since extrapolation beyond the range of observed data is not possible). No single in vitro endpoint was found to exhibit relative superiority with regard to prediction of MAS. Variability associated with Draize test outcome (e.g. in MAS values) must be considered in any future comparisons of in vivo and in vitro test results if the purpose is to predict in vivo response using in vitro data.

Pills and attitude change: misattribution of arousal or excuses for negative actions?

Two experiments evaluated the competing interpretations of cognitive dissonance and impression management theories regarding the pill and misattribution studies of attitude change in the forced compliance situation. Attitude change was eliminated when subjects were told about the tension side effects of taking a placebo, replicating the usual effect. Attitude change was also eliminated, however, when subjects took the pill following counterattitudinal behavior. In one condition of the second experiment, subjects were given instructions about tension side effects but were also told that the drug would not affect their moral judgment or behavior. These instructions eliminated attitude change in a standard pill condition. The typical finding of attitude change was manifested in the misattribution/no-excuse condition. The primary and secondary data from both studies provided more support for the impression management interpretation of the standard misattribution manipulations than for a theory of misattribution of dissonance-produced arousal.

Attraction in aversive environments: some evidence for classical conditioning and negative reinforcement.

Predictions derived from misattribution and negative-reinforcement theories concerning the mediators of attraction in aversive environments were examined. Male subjects, expecting to receive either high- or low-intensity shocks, participated with either a male or female confederate who was or was not present during the description of shock intensity. Subjects' arousal, attributions for their arousal, and attraction to the confederate were measured. Results were not consistent with the misattribution hypothesis. The negative-reinforcement hypothesis accurately predicted the arousal and attribution measures. The presence of the confederate did reduce the perceived aversiveness of the shock and made the subjects feel more calm. Additionally, subjects attributed their arousal to the threat and a calming influence to the confederate. Attraction to the confederate was most consistent with an incorporation of both negative-reinforcement and classical conditioning processes. Confederates who were absent during the high-shock threat were found to be most attractive and significantly more attractive than those who were present during the threat. This suggests that although both confederates reduced arousal, the one present during threat also took on some of the negative qualities of that threat, as would be expected to result from classical conditioning processes.

Clinical performance and specialty choice of COTRANS students.

The clinical performance and specialty choice of 33 Coordinated Transfer Application System (COTRANS) students accepted with advanced standing into the third year of an American medical school were compared with the performance and choice of students from other American medical schools. The undergraduate grade point average of the COTRANS group was considerably lower than that of the other students. The science Medical College Admission Test scores in science were comparable, and the performance on part I of the National Board of Medical Examiners was considerably higher. Clinical performance, choice of specialty, and affiliation of graduate program of the COTRANS students did not differ from those of students entering the curriculum in year 1. Carefully selected students completing the first two years of basic science in a foreign medical school can successfully compete with students already enrolled in the American medical curriculum.

The bogus pipeline as lie detector: two validity studies.

The validity of the bogus pipeline procedure for eliciting truthful responses from subjects in social psychological experiments was tested in two studies. Subjects were illegitimately informed about how to perform well on an experimental test, were tested, and then were asked whether they had possessed this prior information. As compared to subjects responding to pencil-and-paper questions or face-to-face questionning by the experimenter, those in a bogus pipeline condition confessed more often.

Person perception and the Berkowitz paradigm for the study of aggression.

Three experiments in person perception were conducted to investigate the conditions under which naive observers label an actor as aggressive and to ascertain how this label affects the reactions of the observers to the actor. These studies were performed by exposing subjects to written descriptions of Berkowitz's much-used paradigm for the study of aggression in order to additionally demonstrate that naive observers do not label in the same way as do research psychologists. In Experiment 1 the hypothesis was confirmed that harm-doing behavior is labeled as aggression only when it is antinormative. When harm doing was justified by the instigation or attack of another person, its use did not lead to the actor being labeled as aggressive. In Experiment 2 it was found that violation of the limits imposed by the experimenter on the number of shocks that could be used by actors led observers to characterize them as aggressive even when their action was justified by the prior instigation of the other party. Violation of two norms led to a more aggressive rating of the actor than did the violation of only one norm. Experiment 3 showed that actors who are labeled as aggressive are disapproved of and avoided by observers. The results of these studies are discussed in terms of the ecological validity of Berkowitz's research paradigm and metatheoretical implications for the scientific study of harm-doing behavior.

Competitive behavior and perceived aggression.

In groups of 39 males and 39 female undergraduates played a reaction-time game in which descriptions of a player's shock settings were constant or consistently below or above another player's; wins were varied. Ratings of aggression, offensiveness, positivity on semantic scales showed naive subjects considered the offensive or defensive nature of obseved behavior in making ratings.