Slavery and Freedom in Savannah

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High Resolution 8 mm and 1 cm Polarization of IRAS 4A from the VLA Nascent Disk and Multiplicity (VANDAM) Survey

Magnetic fields can regulate disk formation, accretion and jet launching. Until recently, it has been difficult to obtain high resolution observations of the magnetic fields of the youngest protostars in the critical region near the protostar. The VANDAM survey is observing all known protostars in the Perseus Molecular Cloud. Here we present the polarization data of IRAS 4A. We find that with ~ 0.2'' (50 AU) resolution at {\lambda} = 8.1 and 10.3 mm, the inferred magnetic field is consistent with a circular morphology, in marked contrast with the hourglass morphology seen on larger scales. This morphology is consistent with frozen-in field lines that were dragged in by rotating material entering the infall region. The field morphology is reminiscent of rotating circumstellar material near the protostar. This is the first polarization detection of a protostar at these wavelengths. We conclude from our observations that the dust emission is optically thin with {\beta} ~ 1.3, suggesting that mm/cm-sized grains have grown and survived in the short lifetime of the protostar.Comment: Accepted to ApJL. 13 pages, 4 figure

The VLA/ALMA Nascent Disk and Multiplicity (VANDAM) Survey of Perseus Protostars. VI. Characterizing the Formation Mechanism for Close Multiple Systems

We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of multiple protostar systems in the Perseus molecular cloud previously detected by the Karl G. Jansky Very Large Array (VLA). We observed 17 close ($<$600~AU separation) multiple systems at 1.3~mm in continuum and five molecular lines (i.e., \twco, \cateo, \thco, H$_2$CO, SO) to characterize the circum-multiple environments in which these systems are forming. We detect at least one component in the continuum for the 17 multiple systems. In three systems, one companion is not detected, and for two systems the companions are unresolved at our observed resolution. We also detect circum-multiple dust emission toward 8 out of 9 Class 0 multiples. Circum-multiple dust emission is not detected toward any of the 8 Class I multiples. Twelve systems are detected in the dense gas tracers toward their disks/inner envelopes. For these 12 systems, we use the dense gas observations to characterize their formation mechanism. The velocity gradients in the circum-multiple gas are clearly orthogonal to the outflow directions in 8 out of the 12 systems, consistent with disk fragmentation. Moreover, only two systems with separations $<$200~AU are \textit{inconsistent} with disk fragmentation, in addition to the two widest systems ($>$500~AU). Our results suggest that disk fragmentation via gravitational instability is an important formation mechanism for close multiple systems, but further statistics are needed to better determine the relative fraction formed via this method.Comment: 48 Pages, 26 Figures, 7 Tables, Accepted by Ap

Wound care challenges in children and adults with spina bifida: An open-cohort study

Skin breakdown is a frequent concern for individuals with spina bifida. We explored wound incidence in patients with spina bifida and how it varies across a person\u27s life span and functional neurologic level. We examined the settings in which skin breakdown most commonly occurred, looking for evidence of chronic, non-healing wounds. We also sought to develop criteria to improve wound monitoring. We identified reported wound episodes in an open-cohort study over a 13-year period, examining the hospital and outpatient clinical records of spina bifida patients at Children\u27s National Medical Center (CNMC). Current age, age at wound presentation, sex, weight, functional neurologic level, wound location, setting in which the wound was acquired, the development of a chronic wound, and presence of a shunt were recorded. Of the 376 patients in our clinical population, 123 (average age: 18.8 years, range: infancy–56 years) developed a total of 375 wounds; the majority of patients who developed one wound went on to develop one or more additional wounds, and 20 patients developed chronic wounds. Our data suggest that age bracket (adolescents), wheelchair use, and bare feet, as well as possibly obesity and reduced executive functioning, are key risk factors for wound development. These findings have led to a focused effort to increase wound education and prevention. In addition we report on our early experience using a wound care specialist to champion this initiative

Impaired Competence for Pretense in Children with Autism: Exploring Potential Cognitive Predictors.

Lack of pretense in children with autism has been explained by a number of theoretical explanations, including impaired mentalising, impaired response inhibition, and weak central coherence. This study aimed to empirically test each of these theories. Children with autism (n=60) were significantly impaired relative to controls (n=65) when interpreting pretense, thereby supporting a competence deficit hypothesis. They also showed impaired mentalising and response inhibition, but superior local processing indicating weak central coherence. Regression analyses revealed that mentalising significantly and independently predicted pretense. The results are interpreted as supporting the impaired mentalising theory and evidence against competing theories invoking impaired response inhibition or a local processing bias. The results of this study have important implications for treatment and intervention

Vero: A Method for Remotely Studying Human-AI Collaboration

Despite the recognized need in the IS community to prepare for a future of human-AI collaboration, the technical skills necessary to develop and deploy AI systems are considerable, making such research difficult to perform without specialized knowledge. To make human-AI collaboration research more accessible, we developed a novel experimental method that combines a video conferencing platform, controlled content, and Wizard of Oz methods to simulate a group interaction with an AI teammate. Through a case study, we demonstrate the flexibility and ease of deployment of this approach. We also provide evidence that the method creates a highly believable experience of interacting with an AI agent. By detailing this method, we hope that multidisciplinary researchers can replicate it to more easily answer questions that will inform the design and development of future human-AI collaboration technologies

Structure and morphology of light-reflecting synthetic and biogenic polymorphs of isoxanthopterin: A comparison

Until recently it was thought that the only optical function of pteridines in biology was to act as light-absorbing pigments, but a recent report by some of us revealed that crystalline isoxanthopterin is a reflector in the eyes of decapod crustaceans. Here, we report the formation of crystalline isoxanthopterin synthetically from the polar dimethyl sulfoxide solvent, with X-ray diffraction analysis revealing a crystal structure different from that of biogenic isoxanthopterin. The structure of the new polymorph was determined in two independent ways. In one approach, it was generated and optimized using first-principles calculations, followed by comparison of simulation and experiment for high-resolution powder X-ray diffraction (PXRD) and electron diffraction. In the other approach, the structure was obtained definitively from PXRD data using a direct-space genetic algorithm for structure solution followed by Rietveld refinement. The synthetic structure is different from its biogenic counterpart, especially in having a nonplanar criss-cross H-bonded arrangement. We also rationalized the morphology of the crystals and the effect of the DMSO thereon, via a comparison between observed and theoretical growth morphologies. In addition, we calculated the optical properties of the synthetic structure and found its two dominant refractive indices to be somewhat lower than those of its biogenic counterpart, but still as high as those of reflecting guanine crystals. Synthetic isoxanthopterin therefore emerges as a promising candidate for incorporation in artificial optical systems

Interacting with Fictions:The Role of Pretend Play in Theory of Mind Acquisition

Pretend play is generally considered to be a developmental landmark in Theory of Mind acquisition. The aim of the present paper is to offer a new account of the role of pretend play in Theory of Mind development. To this end I combine Hutto and Gallagher’s account of social cognition development with Matravers’ recent argument that the cognitive processes involved in engagement with narratives are neutral regarding fictionality. The key contribution of my account is an analysis of pretend play as interaction with fictions. I argue that my account offers a better explanation of existing empirical data on the development of children’s pretend play and Theory of Mind than the competing theories from Leslie, Perner and Harris