A Neural Network Approach to Identifying YSOs and Exploring Solar Neighborhood Star-Forming History

Stellar ages can act as a marker of birth cluster membership for young stellar objects (YSOs), which allows for an improved understanding of the history of star formation in the solar neighborhood. However, the ages of YSOs have historically been difficult to predict on a large scale. Here, we develop a system of convolution neural network models to differentiate between YSOs and their more-evolved counterparts and predict YSO ages using Gaia and 2MASS photometry. The full model and resulting catalog recovers the properties of well-studied young stellar populations to a distance of five kiloparsecs, with significantly higher sensitivity within one kiloparsec, while also identifying new YSO candidate stars. We then explore the resulting catalog\u27s implications for solar neighborhood star formation, and identify several large-scale structures, including two interesting ring or bubble-shaped groupings of young stars which may suggest radially triggered star forming events. Our results support the existence of an inclined Gould\u27s Belt of local star formation, which may coincide with the Local Bubble. In addition, we also identify 26 high velocity \u27runaway\u27 stars from the Orion Nebula Cluster and characterize their likely origins

Predicting Young Stellar Ages with Deep Learning

Studying the environments of star forming regions is critical to our understanding of early stellar evolution, but historically, observationally distinguishing clustered young stars from evolved field stars has been difficult. The ESA’s Gaia telescope allows for vastly improved cluster membership constraints through spatial and kinematical groupings, but this method fails for gravitationally ejected or high velocity members. Stellar ages, which can be extrapolated on an individual basis from photometric measurements, are a more general alternative to astrometric clustering in identifying cluster membership. We present a deep learning method using Gaia and 2MASS photometry to predict stellar ages for the pre-main-sequence branch. Our model, consisting of two cascading neural networks, is trained to recognize young stars and stellar ages derived from the cluster isochrone fitting of nearby star forming regions. After classifying the evolutionary stage of input stars, the model predicts ages for all sources categorized as pre-main-sequence. Our model successfully recovers known nearby star forming regions while identifying additional candidate members from the Gaia catalog, and shows promise for use in studying extreme stellar kinematics in these regions

Bed nuclei of the stria terminalis modulate memory consolidation via glucocorticoid-dependent and -independent circuits.

There is extensive evidence that glucocorticoid hormones enhance memory consolidation, helping to ensure that emotionally significant events are well remembered. Prior findings suggest that the anteroventral region of bed nuclei of the stria terminalis (avBST) regulates glucocorticoid release, suggesting the potential for avBST activity to influence memory consolidation following an emotionally arousing learning event. To investigate this issue, male Sprague-Dawley rats underwent inhibitory avoidance training and repeated measurement of stress hormones, immediately followed by optogenetic manipulations of either the avBST or its projections to downstream regions, and 48 h later were tested for retention. The results indicate that avBST inhibition augmented posttraining pituitary-adrenal output and enhanced the memory for inhibitory avoidance training. Pretreatment with a glucocorticoid synthesis inhibitor blocked the memory enhancement as well as the potentiated corticosterone response, indicating the dependence of the memory enhancement on glucocorticoid release during the immediate posttraining period. In contrast, posttraining avBST stimulation decreased retention yet had no effect on stress hormonal output. Subsequent experiments revealed that inhibition of avBST input to the paraventricular hypothalamus enhanced stress hormonal output and subsequent retention, whereas stimulation did not affect either. Conversely, stimulation-but not inhibition-of avBST input to the ventrolateral periaqueductal gray impaired consolidation, whereas neither manipulation affected glucocorticoid secretion. These findings indicate that divergent pathways from the avBST are responsible for the mnemonic effects of avBST inhibition versus stimulation and do so via glucocorticoid-dependent and -independent mechanisms, respectively

Bed nuclei of the stria terminalis modulate memory consolidation via glucocorticoid-dependent and -independent circuits

There is extensive evidence that glucocorticoid hormones enhance memory consolidation, helping to ensure that emotionally significant events are well remembered. Prior findings suggest that the anteroventral region of bed nuclei of the stria terminalis (avBST) regulates glucocorticoid release, suggesting the potential for avBST activity to influence memory consolidation following an emotionally arousing learning event. To investigate this issue, male Sprague-Dawley rats underwent inhibitory avoidance training and repeated measurement of stress hormones, immediately followed by optogenetic manipulations of either the avBST or its projections to downstream regions, and 48 h later were tested for retention. The results indicate that avBST inhibition augmented posttraining pituitary-adrenal output and enhanced the memory for inhibitory avoidance training. Pretreatment with a glucocorticoid synthesis inhibitor blocked the memory enhancement as well as the potentiated corticosterone response, indicating the dependence of the memory enhancement on glucocorticoid release during the immediate posttraining period. In contrast, posttraining avBST stimulation decreased retention yet had no effect on stress hormonal output. Subsequent experiments revealed that inhibition of avBST input to the paraventricular hypothalamus enhanced stress hormonal output and subsequent retention, whereas stimulation did not affect either. Conversely, stimulation-but not inhibition-of avBST input to the ventrolateral periaqueductal gray impaired consolidation, whereas neither manipulation affected glucocorticoid secretion. These findings indicate that divergent pathways from the avBST are responsible for the mnemonic effects of avBST inhibition versus stimulation and do so via glucocorticoid-dependent and -independent mechanisms, respectively

Shortwave infrared polymethine fluorophores matched to excitation lasers enable non-invasive, multicolour in vivo imaging in real time.

High-resolution, multiplexed experiments are a staple in cellular imaging. Analogous experiments in animals are challenging, however, due to substantial scattering and autofluorescence in tissue at visible (350-700 nm) and near-infrared (700-1,000 nm) wavelengths. Here, we enable real-time, non-invasive multicolour imaging experiments in animals through the design of optical contrast agents for the shortwave infrared (SWIR, 1,000-2,000 nm) region and complementary advances in imaging technologies. We developed tunable, SWIR-emissive flavylium polymethine dyes and established relationships between structure and photophysical properties for this class of bright SWIR contrast agents. In parallel, we designed an imaging system with variable near-infrared/SWIR excitation and single-channel detection, facilitating video-rate multicolour SWIR imaging for optically guided surgery and imaging of awake and moving mice with multiplexed detection. Optimized dyes matched to 980 nm and 1,064 nm lasers, combined with the clinically approved indocyanine green, enabled real-time, three-colour imaging with high temporal and spatial resolutions

1109. A multicenter, observational study to compare the effectiveness of C eftazidime- A vibactam versus C eftolozane- T azobactam for multidrug-resistant Pseudomonas aeruginosa infections in the U nited S tates (CACTUS)

Abstract Background Ceftolozane-tazobactam (CT) and ceftazidime-avibactam (CZA) are front-line agents for treatment of multidrug-resistant (MDR) Pseudomonas aeruginosa; however, real-world comparative-effectiveness data are lacking. Methods CACTUS is a retrospective, matched, multicenter study to compare the efficacy of CT and CZA among patients with bacteremia or pneumonia due to MDR P. aeruginosa. CT and CZA patients were matched 1:1 within each study site by the presence/absence of septic shock/severe sepsis, infection site, and time to treatment initiation. The primary outcome was clinical success at day 30 defined as survival, resolution of signs/symptoms with the intended treatment course, and absence of recurrent infections. Patients with cystic fibrosis or COVID-19 infection within 90 days were excluded. Results 234 patients were included from 20 sites. Patient demographics, severity of illness, infection types, and treatment durations were similar for patients treated with CT or CZA (Table 1). The overall median age was 61 years, 61% were male, and the median Charlson score was 5. At study drug initiation, 77% of patients were in the ICU, 67% received mechanical ventilation and the median SOFA score was 7. 79% of patients were treated for pneumonia; 72% of which occurred in ventilated patients. The median time from index culture to treatment initiation was 72 hours in both groups; CT patients were more likely to receive a prolonged infusion of ≥3 hours (36% vs 19%; P=0.005). Clinical success occurred in 62% and 55% of patients receiving CT and CZA, respectively (P=0.35; Table 1). Corresponding rates of success for pneumonia were 63% and 52%, respectively (P=0.13; Figure 1). All-cause, 30-day mortality rate was 20% and 19%, respectively. Microbiologic failures, recurrent infections, and development of resistance within 90 days were similar between groups. Time to a composite endpoint of recurrent infection or death within 90 days was similar between groups in the overall analysis and the subgroup of patients with pneumonia (Figure 2). Conclusion In this interim analysis of the CACTUS study, patients treated with CT and CZA had similar clinical outcomes. We plan to continue enrollment up to 420 patients to detect if any differences exist in the efficacy of CT and CZA for MDR P. aeruginosa infections. Disclosures Ryan K. Shields, PharmD, MS, Allergan: Advisor/Consultant|Cidara: Advisor/Consultant|Entasis: Advisor/Consultant|GSK: Advisor/Consultant|Melinta: Advisor/Consultant|Melinta: Grant/Research Support|Menarini: Advisor/Consultant|Merck: Advisor/Consultant|Merck: Grant/Research Support|Pfizer: Advisor/Consultant|Roche: Grant/Research Support|Shionogi: Advisor/Consultant|Shionogi: Grant/Research Support|Utility: Advisor/Consultant|Venatorx: Advisor/Consultant|Venatorx: Grant/Research Support Lilian M. Abbo, MD, MBA, Ferring: Advisor/Consultant|Pfizer: Advisor/Consultant|Regeneron: Grant/Research Support|Shionogi: Advisor/Consultant Ahmed Babiker, MBBS, Roche: Advisor/Consultant Kimberly C. Claeys, PharmD, Abbvie: Advisor/Consultant|bioMérieux Inc.: Advisor/Consultant|bioMérieux Inc.: Speaker|La Jolla Pharmaceuticals: Advisor/Consultant|Melinta Therapeutics: Advisor/Consultant Jason C. Gallagher, PharmD, Entasis: Advisor/Consultant|Merck: Advisor/Consultant|Merck: Grant/Research Support|Qpex: Advisor/Consultant|Shionogi: Advisor/Consultant|Spero: Advisor/Consultant Emily L. Heil, PharmD, MS, Wolters Kluwer-LexiComp: Advisor/Consultant Wesley D. Kufel, PharmD, BCPS, BCIDP, AAHIVP, Merck and Co: Grant/Research Support Amy Mathers, MD, D(ABMM), Merck: Advisor/Consultant Erin K. McCreary, PharmD, Abbvie: Advisor/Consultant|Ferring: Advisor/Consultant|GSK: Honoraria|La Jolla (Entasis): Advisor/Consultant|LabSimply: Advisor/Consultant|Merck: Advisor/Consultant|Shionogi: Advisor/Consultant|Shionogi: Honoraria Christopher Polk, MD, ViiVHealthcare: Job change to work for ViiV as Medical Director Michael J. Satlin, MD, AbbVie: IDMC member|Biomerieux: Grant/Research Support|Merck: Grant/Research Support|SNIPRBiome: Grant/Research Support Michael Veve, PharmD, MPH, National Institutes of Health: Grant/Research Support|Paratek Pharmaceuticals: Grant/Research Support jason M. Pogue, PharmD, AbbVie: Advisor/Consultant|Entasis: Advisor/Consultant|Ferring: Advisor/Consultant|GSK: Advisor/Consultant|Merck: Advisor/Consultant|Merck: Grant/Research Support|Qpex: Advisor/Consultant|Shionogi: Advisor/Consultan