Holocene Glacial History of Renland, East Greenland Reconstructed From Lake Sediments

The Arctic is responding to the modern increase in temperature, resulting in ice loss and consequent sea-level rise. In order to understand present-day changes, we need to understand how the Arctic has reacted in the past to natural variations in climate forcing. To begin to identify the mechanisms behind climate change, I produced a Holocene glacial and climate record for the Renland Ice Cap, Scoresby Sund, East Greenland, from sediments in glacially fed lakes. I cored Rapids and Bunny Lakes, which are fed by meltwater from the Renland Ice Cap, as well as Raven Lake, which does not receive glacial influx at present. The presence or absence of glacial sediments in Rapids and Bunny Lakes gives information on the size of the Renland Ice Cap. I studied multiple sediment characteristics in the cores, including magnetic susceptibility (MS), grain size, organic and carbonate content, and color intensity. In general, I identified glacial sediment as grey, inorganic, and with high MS. Non-glacial material was black or brown with high organic content and low MS. Chronology for the cores came from radiocarbon dating of macrofossils and sieved organic fragments. My results suggest that the region may have deglaciated as early as ~12.5 ka. The high organic content in all three lakes suggests that the early- to mid-Holocene was warm with periods of limited ice extent, consistent with the Holocene thermal maximum, which has been documented elsewhere. After this warmth, the area cooled during the Neoglaciation that culminated in the largest glacial event of the Holocene during the Little Ice Age. Superimposed on the long-term climate change were multiple centennial-to-millennial-scale glacial advances at ~ 9.4, 8.6-8.8, 8.1-8.3, 7.6-7.8, 7.0-7.5, 5.8-6.0, 4.7-5.0, 3.7-4.0, 3.0-3.6, and ~1.0 (AD 600 and 900) cal. kyBP. My reconstruction of variations in the Renland Ice Cap matches well with other glacial records from Scoresby Sund and from the wider Northern Hemisphere. In addition, comparison with other glacial records from the Scoresby Sund region suggests that elevation exerts a strong control on the timing, size, and number of glacial advances exhibited at each site. This highlights the need for caution when comparing glacial records from large geographic areas. The Renland record, along with other Northern Hemisphere data, indicates pervasive millennial-scale climate change throughout the Holocene, with the largest magnitude glacial advance occurring during the Little Ice Age. This pattern favors a cyclical forcing mechanism, such as solar variability or a \u27wobbly ocean conveyor,\u27 rather than unique events, such as volcanic eruptions or outburst floods, as a cause of millennial-scale climate change

Changes in glacial meltwater alter algal communities in lakes of Scoresby Sund, Renland, East Greenland throughout the Holocene: abrupt reorganizations began 1000 years before present

We investigated the response of lake algal communities to changes in glacial meltwater from the Renland Ice Cap (Greenland) through the Holocene to assess whether influxes always elicit consistent responses or novel responses. We measured sedimentary algal pigments in two proximal lakes, snow-fed Raven and glacier- and snow-fed Bunny Lake, and diatom community structure and turnover in Bunny Lake. Diatom data were not available in Raven Lake. We also modeled lake-level change in Bunny Lake to identify how glacial meltwater may have altered diatom habitat availability through time. Through a series of glacier advances and retreats over the Holocene, the algal response in Bunny Lake was relatively constant until approximately 1015 yr BP, after which there were major changes in sedimentary algal remains. Algal pigment concentrations sharply declined, and diatom species richness increased. Diatom community structure underwent three reorganizations. Until 1015 yr BP, assemblages were dominated by Pinnularia braunii and Aulacoseira pffaffiana. However, approximately 1015–480 yr BP, these species declined and Tabellaria flocculosa and Hannaea arcus became a significant component of the assemblage. Approximately 440 yr BP, A. pfaffiana increased along with species indicating elevated nitrogen. In contrast, the algal pigment records from nearby snow-fed Raven Lake showed different and minimal change through time. Our results suggest that changes in the magnitude and composition of meltwater in our two study lakes were unique over the last 1000 yr BP and elicited a non-linear threshold response absent during other periods of glacier advance and retreat. Deciphering the degree to which glaciers structure algal communities over time has strong implications for lakes as glaciers continue to recede

Hemispheric Asymmetry in White Matter Connectivity of the Temporoparietal Junction with the Insula and Prefrontal Cortex

The temporoparietal junction (TPJ) is a key node in the brain's ventral attention network (VAN) that is involved in spatial awareness and detection of salient sensory stimuli, including pain. The anatomical basis of this network's right-lateralized organization is poorly understood. Here we used diffusion-weighted MRI and probabilistic tractography to compare the strength of white matter connections emanating from the right versus left TPJ to target regions in both hemispheres. Symmetry of structural connectivity was evaluated for connections between TPJ and target regions that are key cortical nodes in the right VAN (insula and inferior frontal gyrus) as well as target regions that are involved in salience and/or pain (putamen, cingulate cortex, thalamus). We found a rightward asymmetry in connectivity strength between the TPJ and insula in healthy human subjects who were scanned with two different sets of diffusion-weighted MRI acquisition parameters. This rightward asymmetry in TPJ-insula connectivity was stronger in females than in males. There was also a leftward asymmetry in connectivity strength between the TPJ and inferior frontal gyrus, consistent with previously described lateralization of language pathways. The rightward lateralization of the pathway between the TPJ and insula supports previous findings on the roles of these regions in stimulus-driven attention, sensory awareness, interoception and pain. The findings also have implications for our understanding of acute and chronic pains and stroke-induced spatial hemineglect

Nodal stage of surgically resected non-small cell lung cancer and its effect on recurrence patterns and overall survival

PURPOSE: Current National Comprehensive Cancer Network guidelines recommend postoperative radiation therapy (PORT) for patients with resected non-small cell lung cancer (NSCLC) with N2 involvement. We investigated the relationship between nodal stage and local-regional recurrence (LR), distant recurrence (DR) and overall survival (OS) for patients having an R0 resection. METHODS AND MATERIALS: A multi-institutional database of consecutive patients undergoing R0 resection for stage I-IIIA NSCLC from 1995 to 2008 was used. Patients receiving any radiation therapy before relapse were excluded. A total of 1241, 202, and 125 patients were identified with N0, N1, and N2 involvement, respectively; 161 patients received chemotherapy. Cumulative incidence rates were calculated for LR and DR as first sites of failure, and Kaplan-Meier estimates were made for OS. Competing risk analysis and proportional hazards models were used to examine LR, DR, and OS. Independent variables included age, sex, surgical procedure, extent of lymph node sampling, histology, lymphatic or vascular invasion, tumor size, tumor grade, chemotherapy, nodal stage, and visceral pleural invasion. RESULTS: The median follow-up time was 28.7 months. Patients with N1 or N2 nodal stage had rates of LR similar to those of patients with N0 disease, but were at significantly increased risk for both DR (N1, hazard ratio [HR] = 1.84, 95% confidence interval [CI]: 1.30-2.59; P=.001; N2, HR = 2.32, 95% CI: 1.55-3.48; P \u3c .001) and death (N1, HR = 1.46, 95% CI: 1.18-1.81; P \u3c .001; N2, HR = 2.33, 95% CI: 1.78-3.04; P \u3c .001). LR was associated with squamous histology, visceral pleural involvement, tumor size, age, wedge resection, and segmentectomy. The most frequent site of LR was the mediastinum. CONCLUSIONS: Our investigation demonstrated that nodal stage is directly associated with DR and OS but not with LR. Thus, even some patients with, N0-N1 disease are at relatively high risk of local recurrence. Prospective identification of risk factors for local recurrence may aid in selecting an appropriate population for further study of postoperative radiation therapy

SN 2022oqm–A Ca-rich Explosion of a Compact Progenitor Embedded in C/O Circumstellar Material

We present the discovery and analysis of SN 2022oqm, a Type Ic supernova (SN) detected <1 day after the explosion. The SN rises to a blue and short-lived (2 days) initial peak. Early-time spectral observations of SN 2022oqm show a hot (40,000 K) continuum with high ionization C and O absorption features at velocities of 4000 km s ^−1 , while its photospheric radius expands at 20,000 km s ^−1 , indicating a pre-existing distribution of expanding C/O material. After ∼2.5 days, both the spectrum and light curves evolve into those of a typical SN Ic, with line velocities of ∼10,000 km s ^−1 , in agreement with the evolution of the photospheric radius. The optical light curves reach a second peak at t ≈ 15 days. By t = 60 days, the spectrum of SN 2022oqm becomes nearly nebular, displaying strong Ca ii and [Ca ii ] emission with no detectable [O i ], marking this event as Ca-rich. The early behavior can be explained by 10 ^−3 M _⊙ of optically thin circumstellar material (CSM) surrounding either (1) a massive compact progenitor such as a Wolf–Rayet star, (2) a massive stripped progenitor with an extended envelope, or (3) a binary system with a white dwarf. We propose that the early-time light curve is powered by both the interaction of the ejecta with the optically thin CSM and shock cooling (in the massive star scenario). The observations can be explained by CSM that is optically thick to X-ray photons, is optically thick in the lines as seen in the spectra, and is optically thin to visible-light continuum photons that come either from downscattered X-rays or from the shock-heated ejecta. Calculations show that this scenario is self-consistent

Structure and Funding of Clinical Informatics Fellowships: A National Survey of Program Directors

BackgroundIn 2011, the American Board of Medical Specialties established clinical informatics (CI) as a subspecialty in medicine, jointly administered by the American Board of Pathology and the American Board of Preventive Medicine. Subsequently, many institutions created CI fellowship training programs to meet the growing need for informaticists. Although many programs share similar features, there is considerable variation in program funding and administrative structures.ObjectivesThe aim of our study was to characterize CI fellowship program features, including governance structures, funding sources, and expenses.MethodsWe created a cross-sectional online REDCap survey with 44 items requesting information on program administration, fellows, administrative support, funding sources, and expenses. We surveyed program directors of programs accredited by the Accreditation Council for Graduate Medical Education between 2014 and 2021.ResultsWe invited 54 program directors, of which 41 (76%) completed the survey. The average administrative support received was $27,732/year. Most programs (85.4%) were accredited to have two or more fellows per year. Programs were administratively housed under six departments: Internal Medicine (17; 41.5%), Pediatrics (7; 17.1%), Pathology (6; 14.6%), Family Medicine (6; 14.6%), Emergency Medicine (4; 9.8%), and Anesthesiology (1; 2.4%). Funding sources for CI fellowship program directors included: hospital or health systems (28.3%), clinical departments (28.3%), graduate medical education office (13.2%), biomedical informatics department (9.4%), hospital information technology (9.4%), research and grants (7.5%), and other sources (3.8%) that included philanthropy and external entities.ConclusionCI fellowships have been established in leading academic and community health care systems across the country. Due to their unique training requirements, these programs require significant resources for education, administration, and recruitment. There continues to be considerable heterogeneity in funding models between programs. Our survey findings reinforce the need for reformed federal funding models for informatics practice and training

A 62-minute orbital period black widow binary in a wide hierarchical triple

Over a dozen millisecond pulsars are ablating low-mass companions in close binary systems. In the original ‘black widow’, the eight-hour orbital period eclipsing pulsar PSR J1959+2048 (PSR B1957+20), high-energy emission originating from the pulsar is irradiating and may eventually destroy a low-mass companion. These systems are not only physical laboratories that reveal the interesting results of exposing a close companion star to the relativistic energy output of a pulsar, but are also believed to harbour some of the most massive neutron stars, allowing for robust tests of the neutron star equation of state. Here we report observations of ZTF J1406+1222, a wide hierarchical triple hosting a 62-minute orbital period black widow candidate, the optical flux of which varies by a factor of more than ten. ZTF J1406+1222 pushes the boundaries of evolutionary models, falling below the 80-minute minimum orbital period of hydrogen-rich systems. The wide tertiary companion is a rare low-metallicity cool subdwarf star, and the system has a Galactic halo orbit consistent with passing near the Galactic Centre, making it a probe of formation channels, neutron star kick physics and binary evolution

A very luminous jet from the disruption of a star by a massive black hole

Tidal disruption events (TDEs) are bursts of electromagnetic energy that are released when supermassive black holes at the centres of galaxies violently disrupt a star that passes too close1. TDEs provide a window through which to study accretion onto supermassive black holes; in some rare cases, this accretion leads to launching of a relativistic jet2–9, but the necessary conditions are not fully understood. The best-studied jetted TDE so far is Swift J1644+57, which was discovered in γ-rays, but was too obscured by dust to be seen at optical wavelengths. Here we report the optical detection of AT2022cmc, a rapidly fading source at cosmological distance (redshift z = 1.19325) the unique light curve of which transitioned into a luminous plateau within days. Observations of a bright counterpart at other wavelengths, including X-ray, submillimetre and radio, supports the interpretation of AT2022cmc as a jetted TDE containing a synchrotron ‘afterglow’, probably launched by a supermassive black hole with spin greater than approximately 0.3. Using four years of Zwicky Transient Facility10 survey data, we calculate a rate of 0.02−0.01+0.04 per gigapascals cubed per year for on-axis jetted TDEs on the basis of the luminous, fast-fading red component, thus providing a measurement complementary to the rates derived from X-ray and radio observations11. Correcting for the beaming angle effects, this rate confirms that approximately 1 per cent of TDEs have relativistic jets. Optical surveys can use AT2022cmc as a prototype to unveil a population of jetted TDEs