Adiabatic corrections for velocity-gauge simulations of electron dynamics in periodic potentials

We show how to significantly reduce the number of energy bands required to model the interaction of light with crystalline solids in the velocity gauge. We achieve this by deriving analytical corrections to the electric current density. These corrections depend only on band energies, the matrix elements of the momentum operator, and the macroscopic vector potential. Thus, the corrections can be evaluated independently from modeling the interaction with light. In addition to improving the convergence of velocity-gauge calculations, our analytical approach overcomes the long-standing problem of divergences in expressions for linear and nonlinear susceptibilities.Comment: Submitted to Computer Physics Communication

Attosecond optoelectronic field measurement in solids

The sub-cycle interaction of light and matter is one of the key frontiers of inquiry made accessible by attosecond science. Here, we show that when light excites a pair of charge carriers inside of a solid, the transition probability is strongly localized to instants slightly after the extrema of the electric field. The extreme temporal localization is utilized in a simple electronic circuit to record the waveforms of infrared to ultraviolet light fields. This form of petahertz-bandwidth field metrology gives access to both the modulated transition probability and its temporal offset from the laser field, providing sub-fs temporal precision in reconstructing the sub-cycle electronic response of a solid state structure. Characterization of light pulses is important in order to understand their interaction with matter. Here the authors demonstrate a nonlinear photoconductive sampling method to measure electric field wave-forms in the infrared, visible and ultraviolet spectral ranges

Perceived Adequacy of Tangible Support during Stay-at-Home Orders in Chicago and New York

Objectives: Physical distancing precautions during the COVID-19 pandemic may challenge the provision of tangible support many middle age and older adults receive in managing their health. We examined the association between unmet tangible support needs and self-management behaviors and mental health status during the stay-at-home orders in Chicago and New York. Methods: We used data from the COVID-19 & Chronic Conditions study collected between May 1st and May 22nd, 2020. A total of 801 middle age and older adults with ≥1 chronic condition in Chicago and New York City completed the telephone interview. Adequacy of tangible social support was measured using a brief, validated scale that determined whether an individual needed assistance managing his or her health, and if yes, whether this need was met. Participants reported their level of difficulty engaging in self-management behaviors using 2 discrete items; they also self-reported medication adherence using the ASK-12 medication adherence scale. Mental health status was measured using the depression and anxiety PROMIS short-form instruments. Results: Participants’ mean age was 63 years; 30% identified as Black, 26% identified as Latino, and 12% identified unmet support needs. Inadequacy of tangible support was associated with greater difficulty managing one’s health and accessing medications due to COVID-19, as well as poorer medication adherence, increased anxiety and depressive symptoms, and poorer overall well-being ( P ’s < .05). Conclusions: Perceived unmet support needs during stay-at-home orders were associated with greater difficulty engaging in self-management behaviors and poorer overall well-being. Two brief items quickly identified individuals with unmet support needs

Emotional difficulties in early adolescence following severe early deprivation: findings from the English and Romanian adoptees study

The study assessed conduct and emotional difficulties in a group of Romanian adoptees at age 11, and serves as a follow-up to assessments made when the children were 6 years old. It was found that there was a significant increase in emotional difficulties, but not conduct problems, for the Romanian sample since age 6. It was also found that emotional difficulty was significantly more prevalent at age 11 in the Romanian group than in a within-UK adoptee group. Emotional difficulties in the Romanian adoptee group were found to be significantly and strongly related to previous deprivation-specific problems (disinhibited attachment, cognitive impairment, inattention/overactivity and quasi-autism); however, the presence of such early problems did not account fully for the onset of later emotional problems. Five contrasting hypotheses concerning possible mediators for later onset of emotional difficulties for the Romanian group were examined. No links were found to duration of deprivation or other deprivation-related indices, stresses/difficulties in the postadoption family environment, or educational attainment and self-esteem. There was some evidence that emotion recognition might play a role in the emergence of these problems, but other measures of social competence and theory of mind showed no associations with the onset of emotional problems