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School climate measures are increasingly utilized as one indicator of school quality within educational accountability systems. However, concerns have been raised about the accuracy of these indicators given that school climate surveys are often not validated using multilevel methods. Further, cross-school comparisons in climate may not be trustworthy because the school-level invariance of climate surveys has not been investigated. There is a need to examine the validity of school-level climate constructs and to determine if surveys measure climate equitably for schools that serve underrepresented populations. The aim of the current study was to examine the multilevel factor structure of a statewide school climate survey to determine whether it measured climate equitably for students of different races/ethnicities and across schools with varying racial/ethnic and socioeconomic compositions. Participants included 259,778 students from 427 middle schools throughout a southeastern U.S. state. Cross-level invariance analyses revealed that the climate constructs were measured differently across levels of analysis, and school-level climate could not be interpreted as merely the aggregate of individual-level climate. Student- and school-level factorial invariance was tested using multilevel modeling procedures. Results revealed item bias with respect to student and school characteristics, and the relationships between school climate and student and school demographics changed after accounting for identified bias. As more educational agencies consider including school climate surveys in their accountability systems, these findings suggest that multilevel validation procedures and school-level invariance analyses are necessary to ensure accurate and equitable measurement.

In this study, we take a situationally specific approach to understanding how Black girls perceive, process, and respond to a hypothetical social situation. Through this approach, we aim to contribute to developmental inquiry that resists deficit thinking by foregrounding the voices of Black girls. The current study took place within the participatory culture-specific intervention model and involved 22 early adolescent Black girls (fifth–seventh grade). We conducted semi-structured interviews, asking them to respond to a potentially risky hypothetical situation with a male peer they have just met. Thematic analysis revealed three organizing themes: the overall goal of preserving safety and dignity, a growing ability to handle high-stakes interpersonal interactions, and the expectation of empathy and protection from the community around them. These findings challenge stereotypical portrayals of Black girls as hypersexual and aggressive and add to our understanding of the psychology of Black girls by illustrating their adaptive social decision-making.

There are many measures of student perceptions of school climate; accordingly, there is a staggering amount of research examining those perceptions and related outcomes. There is a comparatively sm...

The aim of the current study was to examine whether collective moral disengagement in the classroom was associated with bullying perpetration and victimisation. One-thousand-and-fifty-four students...

We describe the design of a gravitational wave timing array, a novel scheme that can be used to search for low-frequency gravitational waves by monitoring continuous gravitational waves at higher frequencies. We show that observations of gravitational waves produced by Galactic binaries using a space-based detector like LISA provide sensitivity in the nanohertz to microhertz band. While the expected sensitivity of this proposal is not competitive with other methods, it fills a gap in frequency space around the microhertz regime, which is above the range probed by current pulsar timing arrays and below the expected direct frequency coverage of LISA. The low-frequency extension of sensitivity does not require any experimental design change to space-based gravitational wave detectors, and can be achieved with the data products that would already be collected by them., 18 pages, 6 figures, comments welcome. Matches version accepted for publication in PhysRevD

The planning and design of future experiments rely heavily on forecasting to assess the potential scientific value provided by a hypothetical set of measurements. The Fisher information matrix, due to its convenient properties and low computational cost, provides an especially useful forecasting tool. However, the Fisher matrix only provides a reasonable approximation to the true likelihood when data are nearly Gaussian distributed and observables have nearly linear dependence on the parameters of interest. Also, Fisher forecasting techniques alone cannot be used to assess their own validity. Thorough sampling of the exact or mock likelihood can definitively determine whether a Fisher forecast is valid, though such sampling is often prohibitively expensive. We propose a simple test, based on the Derivative Approximation for LIkelihoods (DALI) technique, to determine whether the Fisher matrix provides a good approximation to the exact likelihood. We show that the Fisher matrix becomes a poor approximation to the true likelihood in regions where two-dimensional slices of level surfaces of the DALI approximation to the likelihood differ from two-dimensional slices of level surfaces of the Fisher approximation to the likelihood. We demonstrate that our method accurately predicts situations in which the Fisher approximation deviates from the true likelihood for various cosmological models and several data combinations, with only a modest increase in computational cost compared to standard Fisher forecasts., Comment: Published in Physical Review D

Researchers have suggested that bystander behaviors and victim coping play an important role in counteracting the negative effects of bullying. The current study investigated the relationship between students' ratings of coping effectiveness when addressing bullying and their behaviors as bystanders when witnessing bullying. Surveys were administered in a Midwestern, suburban school district. Some associations between perceptions of coping effectiveness and bystander behavior supported our hypotheses (e.g., constructive coping associated with defending bystander behaviors, externalizing associated with pro-bullying behaviors). However, some findings did not support hypothesized relationships. For example, higher ratings of effectiveness for cognitive distancing as a coping strategy were associated with increased defending behaviors as a bystander. Gender moderated some of these relationships. Pro-bullying bystander behavior was associated with increased ratings of cognitive distancing and decreased reports of constructive coping effectiveness for girls. Implications for future research and practice are discussed.

We assess the prospects for detecting the moving lens effect using cosmological surveys. The bulk motion of cosmological structure induces a small-scale dipolar temperature anisotropy of the cosmic microwave radiation (CMB), centered around halos and oriented along the transverse velocity field. We introduce a set of optimal filters for this signal, and forecast that a high significance detection can be made with upcoming experiments. We discuss the prospects for reconstructing the bulk transverse velocity field on large scales using matched filters, finding good agreement with previous work using quadratic estimators., Comment: 7 pages, 3 figures, v3: version published in PRD

We present a detailed overview of the science goals and predictions for the Prime-Cam direct detection camera/spectrometer being constructed by the CCAT-prime collaboration for dedicated use on the Fred Young Submillimeter Telescope (FYST). The FYST is a wide-field, 6-m aperture submillimeter telescope being built (first light in mid-2024) by an international consortium of institutions led by Cornell University and sited at more than 5600 meters on Cerro Chajnantor in northern Chile. Prime-Cam is one of two instruments planned for FYST and will provide unprecedented spectroscopic and broadband measurement capabilities to address important astrophysical questions ranging from Big Bang cosmology through reionization and the formation of the first galaxies to star formation within our own Milky Way galaxy. Prime-Cam on the FYST will have a mapping speed that is over ten times greater than existing and near-term facilities for high-redshift science and broadband polarimetric imaging at frequencies above 300 GHz. We describe details of the science program enabled by this system and our preliminary survey strategies., Comment: 61 pages, 16 figures. Resubmitted to ApJSS July 11, 2022

The effects of gravitational lensing of the cosmic microwave background (CMB) have been measured at high significance with existing data and will be measured even more precisely in future surveys. Reversing the effects of lensing on the observed CMB temperature and polarization maps provides a variety of benefits. Delensed CMB spectra have sharper acoustic peaks and more prominent damping tails, allowing for improved inferences of cosmological parameters that impact those features. Delensing reduces $B$-mode power, aiding the search for primordial gravitational waves and allowing for lower variance reconstruction of lensing and other sources of secondary CMB anisotropies. Lensing-induced power spectrum covariances are reduced by delensing, simplifying analyses and improving constraints on primordial non-Gaussianities. Biases that result from incorrectly modeling nonlinear and baryonic feedback effects on the lensing power spectrum are mitigated by delensing. All of these benefits are possible without any changes to experimental or survey design. We develop a self-consistent, iterative, all-orders treatment of CMB delensing on the curved sky and demonstrate the impact that delensing will have with future surveys., Comment: 38 pages, 10 figures. Delensing implementation in CLASS: https://github.com/selimhotinli/class_delens. Fisher forecasting code: https://github.com/ctrendafilova/FisherLens

The cosmic microwave background (CMB) has been a treasure trove for cosmology. Over the next decade, current and planned CMB experiments are expected to exhaust nearly all primary CMB information. To further constrain cosmological models, there is a great benefit to measuring signals beyond the primary modes. Rayleigh scattering of the CMB is one source of additional cosmological information. It is caused by the additional scattering of CMB photons by neutral species formed during recombination and exhibits a strong and unique frequency scaling ($\propto \nu^4$). We will show that with sufficient sensitivity across frequency channels, the Rayleigh scattering signal should not only be detectable but can significantly improve constraining power for cosmological parameters, with limited or no additional modifications to planned experiments. We will provide heuristic explanations for why certain cosmological parameters benefit from measurement of the Rayleigh scattering signal, and confirm these intuitions using the Fisher formalism. In particular, observation of Rayleigh scattering allows significant improvements on measurements of $N_{\rm eff}$ and $\sum m_\nu$., Comment: 20 pages, 10 figures

The commercial sexual exploitation of children (CSEC) is a form of childhood sexual abuse involving the sexual exploitation of youth for economic gain. School-based CSEC prevention efforts have inc...

Student responses to bullying have an effect on subsequent outcomes. Dichotomous theories of coping suggest that self-reliance plays a role in responding to stress. In order to investigate ...

Since their serendipitous discovery, Fast Radio Bursts (FRBs) have garnered a great deal of attention from both observers and theorists. A new class of radio telescopes with wide fields of view have enabled a rapid accumulation of FRB observations, confirming that FRBs originate from cosmological distances. The high occurrence rate of FRBs and the development of new instruments to observe them create opportunities for FRBs to be utilized for a host of astrophysical and cosmological studies. We focus on the rare, and as yet undetected, subset of FRBs that undergo repeated bursts and are strongly gravitationally lensed by intervening structure. An extremely precise timing of burst arrival times is possible for strongly lensed repeating FRBs, and we show how this timing precision enables the search for long wavelength gravitational waves, including those sourced by supermassive black hole binary systems. The timing of burst arrival for strongly lensed repeating FRBs is sensitive to gravitational wave sources near the FRB host galaxy, which may lie at cosmological distances and would therefore be extremely challenging to detect by other means. Timing of strongly lensed FRBs can also be combined with pulsar timing array data to search for correlated time delays characteristic of gravitational waves passing through the Earth., Comment: 13 pages, 4 figures. Updated to match published content. Comments welcome

The UN Convention on the Rights of the Child has delineated numerous principles that serve to promote the welfare of children, and many of these principles have implications for educational policies and practices. School psychologists can advance children’s rights by working with administrators to encourage leadership styles and educational practices that promote these rights. School psychologists can also take administrative positions in schools, working directly to exercise these leadership styles and emphasize children’s rights as a priority. This chapter illustrates how school psychologists can have an impact on school culture by highlighting participatory leadership styles that can be used to transform education. Included is a discussion of how program-centered and consultee-centered administrative consultation can be used by school psychologists to facilitate the efforts of administrators to promote children’s rights. The chapter identifies four themes related to children’s rights that have particularly important implications for transforming education. These include (1) child-centered, nondiscriminatory education; (2) childcare and protection; (3) culture, leisure, and play; and (4) respect for children’s views. The chapter provides two examples of the school psychologist’s role in promoting children’s rights. One illustrates strategies for responding to the theme of childcare and protection, and the other illustrates strategies related to the theme of child-centered, nondiscriminatory education by focusing on child-centered approaches to school discipline. Recommendations are made about the roles that school psychologists can play to promote children’s rights as practitioners, administrators, and researchers.

The light relic density affects the thermal and expansion history of the early Universe leaving a number of observable imprints. We focus on the primordial abundances of light elements produced during the process of Big Bang nucleosynthesis which are influenced by the light relic density. Primordial abundances can be used to infer the density of light relics and thereby serve as a probe of physics beyond the Standard Model. We calculate the observational uncertainty on primordial light element abundances and associated quantities that would be required in order for these measurements to achieve sensitivity to the light relic density comparable to that anticipated from upcoming cosmic microwave background surveys. We identify the nuclear reaction rates that need to be better measured to maximize the utility of future observations. We show that improved measurements of the primordial helium-4 abundance can improve constraints on light relics, while more precise measurements of the primordial deuterium abundance are unlikely to be competitive with cosmic microwave background measurements of the light relic density., 8 pp, 4 figures

We provide an overview of the science case, instrument configuration and project plan for the next-generation ground-based cosmic microwave background experiment CMB-S4, for consideration by the 2020 Decadal Survey.

The cosmic microwave background (CMB) is sensitive to the recent phase of accelerated cosmic expansion through the late-time integrated Sachs-Wolfe (ISW) effect, which manifests as secondary temperature fluctuations on large angular scales. However, the large cosmic variance from primary CMB fluctuations limits the usefulness of this effect in constraining dark energy or modified gravity. In this paper, we propose a novel method to separate the ISW signal from the primary signal using gravitational lensing, based on the fact that the ISW signal is, to a good approximation, not gravitationally lensed. We forecast how well we can isolate the ISW signal for different experimental configurations, and discuss various applications, including modified gravity, large-scale CMB anomalies, and measurements of local-type primordial non-Gaussianity. Although not within reach of current experiments, the proposed method is a unique way to remove the cosmic variance of the primary signal, allowing for better CMB-based constraints on late-time phenomena than previously thought possible., Comment: 9+4 pages, 4 figures. v2: PRD published version, with references and clarifications added (conclusions unchanged)

Cosmic microwave background (CMB) constraints on dark matter annihilation are a uniquely powerful tool in the quest to understand the nature of dark matter. Annihilation of dark matter to Standard Model particles between recombination and reionization heats baryons, ionizes neutral hydrogen, and alters the CMB visibility function. Surprisingly, CMB bounds on dark matter annihilation are not expected to improve significantly with the dramatic improvements in sensitivity expected in future cosmological surveys. In this paper, we will present a simple physical description of the origin of the CMB constraints and explain why they are nearly saturated by current observations. The essential feature is that dark matter annihilation primarily affects the ionization fraction which can only increase substantially at times when the universe was neutral. The resulting change to the CMB occurs on large angular scales and leads to a phenomenology similar to that of the optical depth to reionization. We will demonstrate this impact on the CMB both analytically and numerically. Finally, we will discuss the additional impact that changing the ionization fraction has on large scale structure., Comment: 22 pages, 11 figures

The present study seeks to contribute to qualitative research on students’ perspectives on bystander behaviors to better understand their behaviors in bullying situations. Researchers have found th ...

This commentary underscores efforts of this special issue to highlight concepts related to culture and cultural competence designed to broaden thinking about multicultural consultation through research, practice, and training. It does this by illustrating the insights presented regarding (a) cultural issues in training, (b) the effect of client-centered consultation procedures on supervision of multicultural cognitive behavior therapy, (c) interactions between social capital and cultural variables, and (d) the importance of culturally sensitive research models. Further, this commentary proposes the participatory culture-specific intervention model and organizational consultation as two frameworks that can be used to enhance cultural competence and multicultural consultation in ways that are consistent with the ideas presented in this special issue.

This study investigated associations of general and specific parental self-efficacy factors with bullying and peer victimization behaviors among 142 fourth and fifth graders and their parents. Using structural equation modeling, exploratory factor analysis was used to examine one general parenting self-efficacy measure and a bullying-specific parent self-efficacy measure. The latter produced two unique factors: (a) self-efficacy to know when one’s child is bullied, and (b) self-efficacy to respond to one’s child being bullied. Child reports of bullying and peer victimization were simultaneously regressed on the three (i.e., one general and two specific) parent self-efficacy factors. Findings revealed that parental self-efficacy to know when one’s child is bullied was uniquely and negatively associated with both bullying and victimization. Additionally, and contrary to expectations, parental self-efficacy to respond when one’s child is being bullied was uniquely and positively associated with victi...

The cosmic microwave background (CMB) places a variety of model-independent constraints on the strength interactions of the dominant component of dark matter with the standard model. Percent-level subcomponents of the dark matter can evade the most stringent CMB bounds by mimicking the behavior of baryons, allowing for larger couplings and novel experimental signatures. However, in this Letter, we will show that such tightly coupled subcomponents leave a measurable imprint on the CMB that is well approximated by a change to the helium fraction, ${Y}_{\mathrm{He}}$. Using the existing CMB constraint on ${Y}_{\mathrm{He}}$, we derive a new upper limit on the fraction of tightly coupled dark matter, ${f}_{\mathrm{TCDM}}$, of ${f}_{\mathrm{TCDM}}l0.006$ (95% C.I.). We show that future CMB experiments can reach ${f}_{\mathrm{TCDM}}l0.001$ (95% C.I.) and confirm that the bounds derived in this way agree with the results of a complete analysis. These bounds provide an example of how CMB constraints on ${Y}_{\mathrm{He}}$ have applications beyond studying big bang nucleosynthesis, since tightly coupled dark matter plays no direct role in the formation of light nuclei. We briefly comment on the implications for model building, including millicharged dark matter.

Gravitational potentials which change in time induce fluctuations in the observed cosmic microwave background (CMB) temperature. Cosmological structure moving transverse to our line of sight provides a specific example known as the moving lens effect. Here we explore how the observed CMB temperature fluctuations combined with the observed matter over-density can be used to infer the transverse velocity of cosmological structure on large scales. We show that near-future CMB surveys and galaxy surveys will have the statistical power to make a first detection of the moving lens effect, and we discuss applications for the reconstructed transverse velocity., 5 pages, 4 figures, comments welcome

One evaluation measure available through the Positive Behavioral Interventions and Supports framework is the Effective Behavior Support Self-Assessment Survey (SAS). Evaluations of the SAS have supported its factor structure. However, the SAS is designed to be completed by school personnel who are nested within other levels of analysis (e.g., schools, grade level, district). There have been no studies examining the SAS from a multilevel perspective. The current study addressed this gap by evaluating the SAS using data from 1,726 respondents across 36 public schools in 3 school districts. Another purpose of this study was to evaluate whether the SAS can be shortened yet remain psychometrically sound to encourage completion of the survey by busy school staff members. Intraclass correlation coefficients indicated substantial dependence in item responses. Factor correlations were substantial across all models tested. Compared with a 2nd-order, hierarchical model and the basic 4-factor model based on the original hypothesized structure of the SAS, the best combination of fit and parsimony was obtained from a reduced set of 24 of the original 46 items organized within a multilevel bifactor structure (e.g., comparative fit index = .979, root-mean-square error of approximation = .019), suggesting that the SAS may be shortened. The bifactor model partitioned item variances to a general implementation fidelity factor and to 1 of the 4 hypothesized factors. These results suggest that the SAS items aim to describe dimensions for measuring implementation status that may be as relevant at the school level as they are at the individual level. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

We present the detailed science case, and brief descriptions of the telescope design, site, and first light instrument plans for a new ultra-wide field submillimeter observatory, CCAT-prime, that we are constructing at a 5600 m elevation site on Cerro Chajnantor in northern Chile. Our science goals are to study star and galaxy formation from the epoch of reionization to the present, investigate the growth of structure in the Universe, improve the precision of B-mode CMB measurements, and investigate the interstellar medium and star formation in the Galaxy and nearby galaxies through spectroscopic, polarimetric, and broadband surveys at wavelengths from 200 m to 2 mm. These goals are realized with our two first light instruments, a large field-of-view (FoV) bolometer-based imager called Prime-Cam (that has both camera and an imaging spectrometer modules), and a multi-beam submillimeter heterodyne spectrometer, CHAI. CCAT-prime will have very high surface accuracy and very low system emissivity, so that combined with its wide FoV at the unsurpassed CCAT site our telescope/instrumentation combination is ideally suited to pursue this science. The CCAT-prime telescope is being designed and built by Vertex Antennentechnik GmbH. We expect to achieve first light in the spring of 2021., Ground-based and Airborne Telescopes VII, June 10-15, 2018, Austin, USA, Series: Proceedings of SPIE; no. 10700

We investigate the detection prospects for gravitational lensing of three-dimensional maps from upcoming line intensity surveys, focusing in particular on the impact of gravitational nonlinearities on standard quadratic lensing estimators. Using perturbation theory, we show that these nonlinearities can provide a significant contaminant to lensing reconstruction, even for observations at reionization-era redshifts. However, we show how this contamination can be mitigated with the use of a "bias-hardened" estimator. Along the way, we present an estimator for reconstructing long-wavelength density modes, in the spirit of the "tidal reconstruction" technique that has been proposed elsewhere, and discuss the dominant biases on this estimator. After applying bias-hardening, we find that a detection of the lensing potential power spectrum will still be challenging for the first phase of SKA-Low, CHIME, and HIRAX, with gravitational nonlinearities decreasing the signal to noise by a factor of a few compared to forecasts that ignore these effects. On the other hand, cross-correlations between lensing and galaxy clustering or cosmic shear from a large photometric survey look promising, provided that systematics can be sufficiently controlled. We reach similar conclusions for a single-dish survey inspired by CII measurements planned for CCAT-prime, suggesting that lensing is an interesting science target not just for 21cm surveys, but also for intensity maps of other lines., 40+18 pages, 13 figures, 5 tables. v2: JCAP published version, with typos fixed and clarifications added

The authors map out a high precision strategy to use the yet to be observed polarized $S\phantom{\rule{0}{0ex}}u\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}y\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}v\ensuremath{-}Z\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}{l}^{\ensuremath{'}}\phantom{\rule{0}{0ex}}d\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}v\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}c\phantom{\rule{0}{0ex}}h$ $(p\phantom{\rule{0}{0ex}}S\phantom{\rule{0}{0ex}}Z)$ $e\phantom{\rule{0}{0ex}}f\phantom{\rule{0}{0ex}}f\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}c\phantom{\rule{0}{0ex}}t$ (scattering of CMB photons in collapsed galaxies etc.) to reconstruct the cosmological reionization history, the epoch which marks the emergence of the first luminous sources in our Universe. First detection of the $p\phantom{\rule{0}{0ex}}S\phantom{\rule{0}{0ex}}Z\ensuremath{-}e\phantom{\rule{0}{0ex}}f\phantom{\rule{0}{0ex}}f\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}c\phantom{\rule{0}{0ex}}t$ is expected to occur with upcoming CMB and galaxy surveys, encouraging further exploration of this observable as a probe of cosmology.

Using an ecological model, the individual-, school-, and sociocultural-level characteristics that affect gay–straight alliance (GSA) advisors were examined in the current study. The formation of GSAs has been one way that schools have sought to improve the school climate for lesbian, gay, bisexual, and transgender (LGBT) youth. Limited information is available about the demographics and experiences of GSA advisors who lead these clubs. GSA advisors are on the front line of LGBT advocacy in schools. The purpose of this study is to add to the minimal literature on GSA advisors by describing the demographics and the experiences of the largest known sample of GSA advisors in the research literature. In the current study, 262 GSA advisors provided information through a 67-item survey about their demographic characteristics and their experiences advocating for LGBT youth in schools. The results suggested this sample of advisors was a demographically homogenous group. Exploratory factor analysis identified two d...

School climate has been established as an important construct to measure because of its connections to student psychological, social, and academic outcomes (Anderson, 1982; Koth, Bradshaw, & Leaf, 2008; Kuperminc, Leadbeater, Emmons, & Blatt, 1997). Prior research has also established relationships between student perceptions of school climate and individual (i.e., race and ethnicity, gender), classroom (i.e., class size, academic environment), and school (i.e., school size, teacher characteristics) cultural factors. While these variables provide insight into the ways that students come to experience school climate differently, there still remains a need to examine the effect of additional cultural and ecological variables that also have a proximal effect on students' school experiences and perceptions of climate. The current paper presents the Cultural-Ecological Model of School Climate as a method for understanding the interrelationships between personal characteristics, culture, ecological contexts, an...

Physical review / D 97(2), 023511 (2018). doi:10.1103/PhysRevD.97.023511, We study the sensitivity of cosmological observables to the reheating phase following inflation driven by many scalar fields. We describe a method which allows semi-analytic treatment of the impact of perturbative reheating on cosmological perturbations using the sudden decay approximation. Focusing on $\cal{N}$-quadratic inflation, we show how the scalar spectral index and tensor-to-scalar ratio are affected by the rates at which the scalar fields decay into radiation. We find that for certain choices of decay rates, reheating following multiple-field inflation can have a significant impact on the prediction of cosmological observables., Published by APS, Woodbury, NY

The observed dipole anisotropy of the cosmic microwave background (CMB) temperature is much larger than the fluctuations observed on smaller scales and is dominated by the kinematic contribution from the Doppler shifting of the monopole due to our motion with respect to the CMB rest frame. In addition to this kinematic component, there is expected to be an intrinsic contribution with an amplitude about two orders of magnitude smaller. Here we explore a method whereby the intrinsic CMB dipole can be reconstructed through observation of temperature fluctuations on small scales which result from gravitational lensing. Though the experimental requirements pose practical challenges, we show that one can in principle achieve a cosmic variance limited measurement of the primary dipole using the reconstruction method we describe. Since the primary CMB dipole is sensitive to the largest observable scales, such a measurement would have a number of interesting applications for early universe physics, including testing large-scale anomalies, extending the lever-arm for measuring local non-Gaussianity, and constraining isocurvature fluctuations on super-horizon scales., 7 pages, 3 figures; comments welcome

The Thomson optical depth from reionization is a limiting factor in measuring the amplitude of primordial fluctuations, and hence in measuring physics that affects the low-redshift amplitude, such as the neutrino masses. Current constraints on the optical depth, based on directly measuring large-scale cosmic microwave background (CMB) polarization, are challenging due to foregrounds and systematic effects. Here, we consider an indirect measurement of large-scale polarization, using observed maps of small-scale polarization together with maps of fields that distort the CMB, such as CMB lensing and patchy reionization. We find that very futuristic CMB surveys will be able to reconstruct large-scale polarization, and thus the mean optical depth, using only measurements on small scales., 5 pages, 2 figs. Comments welcome

Primordial gravitational waves leave a characteristic imprint on the cosmic microwave background (CMB) in the form of $B$-mode polarization. Photons are also deflected by large scale gravitational waves which intervene between the source screen and our telescopes, resulting in curl-type gravitational lensing. Gravitational waves present at the epoch of reionization contribute to both effects, thereby leading to a non-vanishing cross-correlation between $B$-mode polarization and curl lensing of the CMB. Observing such a cross correlation would be very strong evidence that an observation of $B$-mode polarization was due to the presence of large scale gravitational waves, as opposed to astrophysical foregrounds or experimental systematic effects. We study the cross-correlation across a wide range of source redshifts and show that a post-SKA experiment aimed to map out the 21-cm sky between $15 \leq z \leq 30$ could rule out non-zero cross-correlation at high significance for $r \geq 0.01$., 7 pages, 4 figures. Comments welcome

This book lays out the scientific goals to be addressed by the next-generation ground-based cosmic microwave background experiment, CMB-S4, envisioned to consist of dedicated telescopes at the South Pole, the high Chilean Atacama plateau and possibly a northern hemisphere site, all equipped with new superconducting cameras. CMB-S4 will dramatically advance cosmological studies by crossing critical thresholds in the search for the B-mode polarization signature of primordial gravitational waves, in the determination of the number and masses of the neutrinos, in the search for evidence of new light relics, in constraining the nature of dark energy, and in testing general relativity on large scales.