51 research outputs found

    Exploring Resilience Models in a Sample of Combat-Exposed Military Service Members and Veterans: A Comparison and Commentary

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    Background: The term resilience is applied in numerous ways in the mental health field, leading to different perspectives of what constitutes a resilient response and disparate findings regarding its prevalence following trauma. Objective: illustrate the impact of various definitions on our understanding and prevalence of resilience, we compared various resilience definitions (absence of PTSD, absence of current mental health diagnosis, absence of generalized psychological distress, and an alternative trauma load–resilience discrepancy model of the difference between actual and predicted distress given lifetime trauma exposure) within a combat-exposed military personnel and veteran sample. Method: In this combat-trauma exposed sample (N = 849), of which approximately half were treatment seeking, rates of resilience were determined across all models, the kappa statistic was used to determine the concordance and strength of association across models, and t-tests examined the models in relation to a self-reported resilience measure. Results: Prevalence rates were 43.7%, 30.7%, 87.4%, and 50.1% in each of the four models. Concordance analyses identified 25.7% (n = 218) considered resilient by all four models (kappa = .40, p \u3c .001). Correlations between models and self-reported resilience were strong, but did not fully overlap. Conclusions:The discussion highlights theoretical considerations regarding the impact of various definitions and methodologies on resilience classifications, links current findings to a systems-based perspective, and ends with suggestions for future research approaches on resilience

    Extremely Red Galaxies at z = 5-9 with MIRI and NIRSpec:Dusty Galaxies or Obscured Active Galactic Nuclei?

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    We study a new population of extremely red objects (EROs) recently discovered by the James Webb Space Telescope (JWST) based on their NIRCam colors F277W − F444W &gt; 1.5 mag. We find 37 EROs in the Cosmic Evolution Early Release Science Survey (CEERS) field with F444W &lt; 28 mag and photometric redshifts between 5 &lt; z &lt; 7, with median z = 6.9 − 1.6 + 1.0 . Surprisingly, despite their red long-wavelength colors, these EROs have blue short-wavelength colors (F150W − F200W ∼ 0 mag) indicative of bimodal spectral energy distributions (SEDs) with a red, steep slope in the rest-frame optical, and a blue, flat slope in the rest-frame UV. Moreover, all these EROs are unresolved, point-like sources in all NIRCam bands. We analyze the SEDs of eight of them with MIRI and NIRSpec observations using stellar population models and active galactic nucleus (AGN) templates. We find that dusty galaxies or obscured AGNs provide similarly good SED fits but different stellar properties: massive and dusty, log M ⋆ / M ⊙ ∼ 10 and A V ≳ 3 mag, or low mass and obscured, log M ⋆ / M ⊙ ∼ 7.5 and A V ∼ 0 mag, hosting an obscured quasi-stellar object (QSO). SED modeling does not favor either scenario, but their unresolved sizes are more suggestive of AGNs. If any EROs are confirmed to have log M ⋆ / M ⊙ ≳ 10.5, it would increase the pre-JWST number density at z &gt; 7 by up to a factor ∼60. Similarly, if they are QSOs with luminosities in the L bol &gt; 1045-46 erg s−1 range, their number would exceed that of bright blue QSOs by more than three orders of magnitude. Additional photometry at mid-infrared wavelengths will reveal the true nature of the red continuum emission in these EROs and will place this puzzling population in the right context of galaxy evolution.</p

    CEERS Key Paper VII: Emission Line Ratios from NIRSpec and NIRCam Wide-Field Slitless Spectroscopy at z>2

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    We use James Webb Space Telescope Near-Infrared Camera Wide Field Slitless Spectroscopy (NIRCam WFSS) and Near-Infrared spectrograph (NIRSpec) in the Cosmic Evolution Early Release survey (CEERS) to measure rest-frame optical emission-line of 155 galaxies at z>2. The blind NIRCam grism observations include a sample of galaxies with bright emission lines that were not observed on the NIRSpec masks. We study the changes of the Ha, [OIII]/Hb, and [NeIII]/[OII] emission lines in terms of redshift by comparing to lower redshift SDSS and CLEAR samples. We find a significant (>3σ\sigma) correlation between [OIII]/Hb with redshift, while [NeIII]/[OII] has a marginal (2σ\sigma) correlation with redshift. We compare [OIII]/Hb and [NeIII]/[OII] to stellar mass and Hb SFR. We find that both emission-line ratios have a correlation with Hb SFR and an anti-correlation with stellar mass across the redshifts 0<z<9. Comparison with MAPPINGS~V models indicates that these trends are consistent with lower metallicity and higher ionization in low-mass and high-SFR galaxies. We additionally compare to IllustriousTNG predictions and find that they effectively describe the highest [OIII]/Hb ratios observed in our sample, without the need to invoke MAPPINGS models with significant shock ionizionation components.Comment: 16 pages, 11 figure

    First Look at z > 1 Bars in the Rest-Frame Near-Infrared with JWST Early CEERS Imaging

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    Stellar bars are key drivers of secular evolution in galaxies and can be effectively studied using rest-frame near-infrared (NIR) images, which trace the underlying stellar mass and are less impacted by dust and star formation than rest-frame UV or optical images. We leverage the power of {\it{JWST}} CEERS NIRCam images to present the first quantitative identification and characterization of stellar bars at z>1z>1 based on rest-frame NIR F444W images of high resolution (~1.3 kpc at z ~ 1-3). We identify stellar bars in these images using quantitative criteria based on ellipse fits. For this pilot study, we present six examples of robustly identified bars at z>1z>1 with spectroscopic redshifts, including the two highest redshift bars at ~2.136 and 2.312 quantitatively identified and characterized to date. The stellar bars at zz ~ 1.1-2.3 presented in our study have projected semi-major axes of ~2.9-4.3 kpc and projected ellipticities of ~0.41-0.53 in the rest-frame NIR. The barred host galaxies have stellar masses ~ 1×1010 1 \times 10^{10} to 2×10112 \times 10^{11} M⊙M_{\odot}, star formation rates of ~ 21-295 M⊙M_{\odot} yr−1^{-1}, and several have potential nearby companions. Our finding of bars at zz ~1.1-2.3 demonstrates the early onset of such instabilities and supports simulations where bars form early in massive dynamically cold disks. It also suggests that if these bars at lookback times of 8-10 Gyr survive out to present epochs, bar-driven secular processes may operate over a long time and have a significant impact on some galaxies by z ~ 0.Comment: 16 pages, 5 figures. Accepted for Publication in Astrophysical Journal Letter

    First Look at z &gt; 1 Bars in the Rest-frame Near-infrared with JWST Early CEERS Imaging

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    Stellar bars are key drivers of secular evolution in galaxies and can be effectively studied using rest-frame near-infrared (NIR) images, which trace the underlying stellar mass and are less impacted by dust and star formation than rest-frame UV or optical images. We leverage the power of JWST CEERS NIRCam images to present the first quantitative identification and characterization of stellar bars at z &gt; 1 based on rest-frame NIR F444W images of high resolution (∼1.3 kpc at z ∼ 1-3). We identify stellar bars in these images using quantitative criteria based on ellipse fits. For this pilot study, we present six examples of robustly identified bars at z &gt; 1 with spectroscopic redshifts, including the two highest-redshift bars at z ∼ 2.136 and 2.312 quantitatively identified and characterized to date. The stellar bars at z ∼ 1.1-2.3 presented in our study have projected semimajor axes of ∼2.9-4.3 kpc and projected ellipticities of ∼0.41-0.53 in the rest-frame NIR. The barred host galaxies have stellar masses ∼1 × 10 10 to 2 × 10 11 M ⊙ and star formation rates of ∼21-295 M ⊙ yr −1, and several have potential nearby companions. Our finding of bars at z ∼ 1.1-2.3 demonstrates the early onset of such instabilities and supports simulations where bars form early in massive dynamically cold disks. It also suggests that if these bars at lookback times of 8-11 Gyr survive out to present epochs, bar-driven secular processes may operate over a long time and have a significant impact on some galaxies by z ∼ 0.</p

    Development of Sexually Abusive Behavior in Adolescent Males Who Have Been Sexually Victimized

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    Childhood sexual abuse is represents a significant public health problem in the United States, as 21% of U.S. children experience sexual victimization prior to age 18. Research dedicated to preventing further sexual victimization has identified factors that influence the development of sexually abusive behavior. The abused-abuser hypothesis suggests that a prior history of sexual victimization may increase the risk of engaging in sexually abusive behavior among some victims. Some research has also investigated the relationship between characteristics of an individual\u27s experiences of sexual abuse and the characteristics of their own sexually abusive behavior, but such research is scarce with inconsistent findings. For the present study, we first hypothesized that childhood sexual victimization is more prevalent among those who have engaged in sexually abusive behavior than those who have not. We also posited that among those who have engaged in sexually abusive behavior, their own sexual abuse experiences contribute to victim Page 188 2017 Appalachian Student Research Forum choice, the age at which they begin sexually abusing others, and the frequency of abuse. Our sample (N=529; 100% male; 84.7% Caucasian; M = 17.71) consisted of participants from two larger studies of university students with no known history of sexually abusive behavior (n = 286; 84.6% Caucasian; M = 20.18) and youth who have engaged in sexually abusive behaviors and received residential treatment in the Southeastern U.S (n = 243; 84.8% Caucasian; M =14.79). Data from university students were self-reported, while data from the residential youth were coded from archival records. Results of a chisquare analysis revealed that youth who have engaged in sexually abusive behavior were significantly more likely to have experienced childhood sexual abuse than non-sexual abusers, 2 (1, N=523) =210.788, p = .000. Additionally, within the sample of youth who have engaged in sexually abusive behavior, correlations were used to examine relationships between characteristics of their own sexual perpetrators and their victim choice. Results indicate being victimized by a male is significantly associated with having a male victim (r= .143, p=.033), being victimized by a relative is associated with sexually abusing a relative (r=.148, p=.024), and being victimized by a non-relative is associated with sexually abusing a non-relative (r=.194, p=.033). Findings thus far indicate that youth who have engaged in sexually abusive behavior have not only experienced greater sexual victimization than non-sexual abusers, but that the characteristics of their sexual perpetrators may relate to how they sexually abuse others, specifically with regard to victim choice. Additional analyses will examine whether these characteristics of sexual victimization influence the age of onset of their sexual offending and their number of arrests, sexual offenses, and victims. Future directions and limitations will also be explored
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