Neutrino spin relaxation in medium with stochastic characteristics

The helicity evolution of a neutrino interacting with randomly moving and polarized matter is studied. We derive the equation for the averaged neutrino helicity. The type of the neutrino interaction with background fermions is not fixed. In the particular case of a tau-neutrino interacting with ultrarelativistic electron-positron plasma we obtain the expression for the neutrino helicity relaxation rate in the explicit form. We study the neutrino spin relaxation in the relativistic primordial plasma. Supposing that the conversion of left-handed neutrinos into right-handed ones is suppressed at the early stages of the Universe evolution we get the upper limit on the tau-neutrino mass.Comment: 6 pages, RevTeX4; 2 references added; more detailed discussion of correlation functions and cosmological neutrinos is presented; version to be published in Int. J. Mod. Phys.

Bootstrap tomography of high-precision pulses for quantum control

Long-time dynamical decoupling and quantum control of qubits require high-precision control pulses. Full characterization (quantum tomography) of imperfect pulses presents a bootstrap problem: tomography requires initial states of a qubit which can not be prepared without imperfect pulses. We present a protocol for pulse error analysis, specifically tailored for a wide range of the single solid-state electron spins. Using a single electron spin of a nitrogen-vacancy (NV) center in diamond, we experimentally verify the correctness of the protocol, and demonstrate its usefulness for quantum control tasks

Paternal Parenting Stress during Middle Childhood: The Impact of COVID-19

Background: Parenting stress is the unpleasant psychological reaction to the demands of parenthood, including perceptions of competence at and knowledge of the day-to-day and long-term tasks of parenting (Deater-Deckard 2006). While most research has examined mothers, father parenting stress is also critical to children’s development, predicting increased problem behaviors (Cabrera & Mitchell 2009) and poorer cognitive skills (Harwood, 2017). The COVID-19 pandemic may increase parental stress in multiple ways, as parents are at home more with their children while fulfilling occupational and personal responsibilities. Parents have reported increased stress due to job loss, school closures, and other stressors (van Tilburg et al., 2020), and COVID-19 stressors are associated with higher parental stress in mothers (Brown et al., 2020). This study aimed to examine: 1) how parenting stress in fathers relates to sociodemographics; 2) how COVID-19 may impact parenting stress, relative to sociodemographics. It was hypothesized that 1) fathers in families with less education or income, unmarried, or living in rural areas would report higher parenting stress, and 2) COVID-19 would contribute to parenting stress over and above sociodemographics. Methods: Participants were fathers (n=172) of children ages 6-10, living in the United States, and had at least regular visitation with their child. Fathers were surveyed once through Amazon’s Mechanical Turk between November 2020 through February 2021. The sample was 58% White, 18.6% Black, 7.6% Hispanic, 7.6% Asian American/Pacific Islander, 8.1% All Other Races and Ethnicities, and 97.1% worked full-time. Measures included the Parent-Child Dysfunctional Interaction subscale of the Parenting Stress Index, 4th Edition Short Form (Abidin, 2012), the COVID-19 Impact Scale (Kaufman & Stoddard, 2020), and demographic factors (father age, household income, perceived social class, marital status, education, and urban/rural environment). Results: COVID-19 impact was positively associated with the parenting stress (parent-child dysfunction subscale; r=.50, p\u3c.001). Greater parenting stress was also associated with higher perceived social class (r=.237, p\u3c.001), more education (r=.24, p\u3c.001), and being married (t(155)=-2.81, p=.006). Fathers in urban environments endorsed more parenting stress (t(170)=2.57, p=.011) than those in rural environments. There were no significant associations between father age or household income with parenting stress. Regressions indicated COVID-19 impact was associated with parenting stress (ꞵ=.446, R2=.318, p\u3c.001) over and above the impact of marital status, perceived social class, urban/rural environment, and education level. Blocked regression indicated that COVID-19 impact was associated with parenting stress over and above sociodemographic factors. Block 1 explained 12% of the variance in parenting stress while adding COVID-19 impact to Block 2 explained 31% of the variance in parenting stress. Discussion: COVID-19 and parenting stress were strongly associated with one another. However, contrary to hypotheses, fathers who were married, more educated, identified with higher social classes, or lived in urban environments reported more parenting stress. This may be due to the impact of COVID-19, such that married fathers may have more time with their children, fathers with higher education or perceived social class may be working from home more, and urban areas may have seen more dramatic changes to daily life. Fathers more impacted by COVID-19 may benefit from additional supports or services to reduce demands and parenting stress. Although a single timepoint and single-reporter measurement, findings suggest that interventions designed to reduce COVID-19 related stressors may, in turn, benefit other aspects of family well-being

Uncovering trends in gene naming

A survey of unusual gene names reveals trends underlying their choice

The role of the slope of `realistic' potential barriers in preventing relativistic tunnelling in the Klein zone

The transmission of fermions of mass m and energy E through an electrostatic potential barrier of rectangular shape (i.e. supporting an infinite electric field), of height U> E + m - due to the many-body nature of the Dirac equation evidentiated by the Klein paradox - has been widely studied. We exploit here the analytical solution, given by Sauter for the linearly rising potential step, to show that the tunnelling rate through a more realistic trapezoidal barrier is exponentially depressed, as soon as the length of the regions supporting a finite electric field exceeds the Compton wavelenght of the particle - the latter circumstance being hardly escapable in most realistic cases

Anisotropy of the Cosmic Neutrino Background

The cosmic neutrino background (CNB) consists of low-energy relic neutrinos which decoupled from the cosmological fluid at a redshift z ~ 10^{10}. Despite being the second-most abundant particles in the universe, direct observation remains a distant challenge. Based on the measured neutrino mass differences, one species of neutrinos may still be relativistic with a thermal distribution characterized by the temperature T ~ 1.9K. We show that the temperature distribution on the sky is anisotropic, much like the photon background, experiencing Sachs-Wolfe and integrated Sachs-Wolfe effects.Comment: 5 pages, 2 figures / updated references, discussion of earlier wor

Modeling ChIP Sequencing In Silico with Applications

ChIP sequencing (ChIP-seq) is a new method for genomewide mapping of protein binding sites on DNA. It has generated much excitement in functional genomics. To score data and determine adequate sequencing depth, both the genomic background and the binding sites must be properly modeled. To develop a computational foundation to tackle these issues, we first performed a study to characterize the observed statistical nature of this new type of high-throughput data. By linking sequence tags into clusters, we show that there are two components to the distribution of tag counts observed in a number of recent experiments: an initial power-law distribution and a subsequent long right tail. Then we develop in silico ChIP-seq, a computational method to simulate the experimental outcome by placing tags onto the genome according to particular assumed distributions for the actual binding sites and for the background genomic sequence. In contrast to current assumptions, our results show that both the background and the binding sites need to have a markedly nonuniform distribution in order to correctly model the observed ChIP-seq data, with, for instance, the background tag counts modeled by a gamma distribution. On the basis of these results, we extend an existing scoring approach by using a more realistic genomic-background model. This enables us to identify transcription-factor binding sites in ChIP-seq data in a statistically rigorous fashion

Identification and analysis of unitary pseudogenes: historic and contemporary gene losses in humans and other primates

Novel human pseudogenes are identified that had previous functionality and their age is estimated. The rate of loss-of-function occurred uniformly

Communications Biophysics

Contains reports on three research projects.United States Air Force (Contract AF19(604)-4112