City of New York

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A domain-specific analysis system for examining nuclear reactor simulation data for light-water and sodium-cooled fast reactors

Building a new generation of fission reactors in the United States presents many technical and regulatory challenges. One important challenge is the need to share and present results from new high-fidelity, high-performance simulations in an easily usable way. Since modern multiscale, multi-physics simulations can generate petabytes of data, they will require the development of new techniques and methods to reduce the data to familiar quantities of interest (e.g., pin powers, temperatures) with a more reasonable resolution and size. Furthermore, some of the results from these simulations may be new quantities for which visualization and analysis techniques are not immediately available in the community and need to be developed. This paper describes a new system for managing high-performance simulation results in a domain-specific way that naturally exposes quantities of interest for light water and sodium-cooled fast reactors. It describes requirements to build such a system and the technical challenges faced in its development at all levels (simulation, user interface, etc.). An example comparing results from two different simulation suites for a single assembly in a light-water reactor is presented, along with a detailed discussion of the system's requirements and design.Comment: Article on NiCE's Reactor Analyzer. 23 pages. Keywords: modeling, simulation, analysis, visualization, input-outpu

School Segregation, Educational Attainment, and Crime: Evidence from the End of Busing in Charlotte-Mecklenburg

We study the impact of the end of race-based busing in Charlotte-Mecklenburg schools (“CMS”) on academic achievement, educational attainment, and young adult crime. In 2001, CMS was prohibited from using race in assigning students to schools. School boundaries were redrawn dramatically to reflect the surrounding neighborhoods, and half of its students received a new assignment. Using addresses measured prior to the policy change, we compare students in the same neighborhood that lived on opposite sides of a newly drawn boundary. We find that both white and minority students score lower on high school exams when they are assigned to schools with more minority students. We also find decreases in high school graduation and four-year college attendance for whites, and large increases in crime for minority males. The impacts on achievement and attainment are smaller in younger cohorts, while the impact on crime remains large and persistent for at least nine years after the re-zoning. We show that compensatory resource allocation policies in CMS likely played an important role in mitigating the impact of segregation on achievement and attainment, but had no impact on crime. We conclude that the end of busing widened racial inequality, despite efforts by CMS to mitigate the impact of increases in segregation

The contribution of organisational factors to vicarious trauma in mental health professionals: a systematic review and narrative synthesis

Background: The negative impact of trauma work has been well documented in mental health professionals. There are three main phenomena used to describe these effects: Secondary Traumatic Stress (STS), Vicarious Trauma (VT) and Compassion Fatigue (CF). To date, the majority of research has focused on the contribution of individual level factors. However, it is imperative to also understand the role of organizational factors. Objectives: This review examines the role of organizational factors in ameliorating or preventing STS, VT, and CF in mental health professionals. We further aimed to identify specific elements of these factors which are perceived to be beneficial and/or detrimental in mitigating against the effects of STS, VT, and CF. Method: Studies were identified by searching the electronic databases Medline, PsycINFO, Embase, Web of Science and SCOPUS with final searches taking place on 10 March 2021. Results: Twenty-three quantitative studies, eight qualitative studies, and five mixed methods studies were included in the final review. A narrative synthesis was conducted to analyse the findings. The results of the review highlight the importance of regular supervision within supportive supervisory relationships, strong peer support networks, and balanced and diverse caseloads. The value of having an organizational culture which acknowledges and validates the existence of STS was also imperative. Conclusions: Organizations have an ethical responsibility to support the mental health professionals they employ and provide a supportive environment which protects them against STS. This review provides preliminary evidence for the types of support that should be offered and highlights the gaps in the literature and where future research should be directed. Further research is needed to evaluate which strategies–and under what conditions–best ameliorate and prevent STS

Improved model identification for non-linear systems using a random subsampling and multifold modelling (RSMM) approach

In non-linear system identification, the available observed data are conventionally partitioned into two parts: the training data that are used for model identification and the test data that are used for model performance testing. This sort of 'hold-out' or 'split-sample' data partitioning method is convenient and the associated model identification procedure is in general easy to implement. The resultant model obtained from such a once-partitioned single training dataset, however, may occasionally lack robustness and generalisation to represent future unseen data, because the performance of the identified model may be highly dependent on how the data partition is made. To overcome the drawback of the hold-out data partitioning method, this study presents a new random subsampling and multifold modelling (RSMM) approach to produce less biased or preferably unbiased models. The basic idea and the associated procedure are as follows. First, generate K training datasets (and also K validation datasets), using a K-fold random subsampling method. Secondly, detect significant model terms and identify a common model structure that fits all the K datasets using a new proposed common model selection approach, called the multiple orthogonal search algorithm. Finally, estimate and refine the model parameters for the identified common-structured model using a multifold parameter estimation method. The proposed method can produce robust models with better generalisation performance

Development of Aluminum LEKIDs for Balloon-Borne Far-IR Spectroscopy

We are developing lumped-element kinetic inductance detectors (LEKIDs) designed to achieve background-limited sensitivity for far-infrared (FIR) spectroscopy on a stratospheric balloon. The Spectroscopic Terahertz Airborne Receiver for Far-InfraRed Exploration (STARFIRE) will study the evolution of dusty galaxies with observations of the [CII] 158 $\mu$m and other atomic fine-structure transitions at $z=0.5-1.5$, both through direct observations of individual luminous infrared galaxies, and in blind surveys using the technique of line intensity mapping. The spectrometer will require large format ($\sim$1800 detectors) arrays of dual-polarization sensitive detectors with NEPs of $1 \times 10^{-17}$ W Hz$^{-1/2}$. The low-volume LEKIDs are fabricated with a single layer of aluminum (20 nm thick) deposited on a crystalline silicon wafer, with resonance frequencies of $100-250$ MHz. The inductor is a single meander with a linewidth of 0.4 $\mu$m, patterned in a grid to absorb optical power in both polarizations. The meander is coupled to a circular waveguide, fed by a conical feedhorn. Initial testing of a small array prototype has demonstrated good yield, and a median NEP of $4 \times 10^{-18}$ W Hz$^{-1/2}$.Comment: accepted for publication in Journal of Low Temperature Physic

Global prevalence and risk factors for mental health problems in police personnel: a systematic review and meta-analysis

Police face an increased risk of developing mental health problems, yet reliable estimates of their psychological difficulties remain unknown. This systematic review and meta-analysis estimate the pooled prevalence and risk factors for mental health problems among police personnel worldwide. Three independent reviewers searched 16 databases and screened 11 506 articles published between January 1980 and October 2019. Eligible studies involved at least 100 active police professionals and used validated instruments to ascertain specific mental health problems. Estimates were pooled using random-effects meta-analyses. In total, 60 cross-sectional and seven longitudinal studies, involving 272 463 police personnel from 24 countries met criteria for inclusion. The overall pooled point prevalence was 14.6% for depression (95% CI 10.9% to 18.6%), 14.2% for post-traumatic stress disorder (PTSD; 95% CI 10.3% to 18.7%), 9.6% for a generalised anxiety disorder (95% CI 6.7% to 12.9%), 8.5% for suicidal ideation (95% CI 6.1% to 11.2%), 5.0% for alcohol dependence (95% CI 3.5% to 6.7%) and 25.7% for hazardous drinking (95% CI 19.6% to 32.4%). The strongest risk factor for depression and suicidal ideation was higher occupational stress, and the strongest risk factors for PTSD were higher occupational stress and avoidant coping strategies. Higher levels of peer-support were associated with significantly lower PTSD symptoms. Our findings suggest that the prevalence of mental health problems among police exceeds twice that previously reported in mixed samples of first responders, and is associated with poor social support, occupational stress and maladaptive coping strategies. Without effective intervention, psychological difficulties will remain a substantial health concern among police