506 research outputs found
The effects of marine eukaryote evolution on phosphorus, carbon and oxygen cycling across the Proterozoic–Phanerozoic transition
This is the final version of the article. Available from Portland Press via the DOI in this record.A ‘Neoproterozoic oxygenation event’ is widely invoked as a causal factor in animal evolution, and often attributed to abiotic causes such as post-glacial pulses of phosphorus weathering. However, recent evidence suggests a series of transient ocean oxygenation events ∼660–520 Ma, which do not fit the simple model of a monotonic rise in atmospheric
oxygen (pO2). Hence, we consider mechanisms by which the evolution of marine eukaryotes, coupled with biogeochemical and ecological feedbacks, potentially between alternate stable states, could have caused changes in ocean carbon cycling and redox state, phosphorus cycling and atmospheric pO2. We argue that the late Tonian ocean ∼750 Ma
was dominated by rapid microbial cycling of dissolved organic matter (DOM) with elevated nutrient (P) levels due to inefficient removal of organic matter to sediments. We suggest the abrupt onset of the eukaryotic algal biomarker record ∼660–640 Ma was linked to an escalation of protozoan predation, which created a ‘biological pump’ of sinking particulate
organic matter (POM). The resultant transfer of organic carbon (Corg) and phosphorus to sediments was strengthened by subsequent eukaryotic innovations, including the advent of sessile benthic animals and mobile burrowing animals. Thus, each phase of eukaryote evolution tended to lower P levels and oxygenate the ocean on ∼104 year timescales, but
by decreasing Corg/P burial ratios, tended to lower atmospheric pO2 and deoxygenate the ocean again on ∼106 year timescales. This can help explain the transient nature and ∼106 year duration of oceanic oxygenation events through the Cryogenian–Ediacaran–CambrianThis work was supported by the NERC-NSFC programme ‘Biosphere Evolution, Transitions and Resilience’ through grant NE/P013651/1
In newborn babies, what are the risks of developing Vitamin K deficiency bleeding disorders if not provided IM Vitamin K injection at birth?
Vitamin K, which is produced in the large intestines of adults, is naturally lacking in neonates. It is a crucial part in the clotting cascade for activating clotting factors II, VII, IX, and X. For the past several decades, it has been a standard in Western Medicine to give an IM Vitamin K injection to neonates post birth. In recent years, statistics of refusal have continued to grow creating an increased prevalence of Vitamin K Deficiency Bleeding Disorders. This study is aimed at exploring the statistics of injection refusal, reasons for refusal, alternative methods to injections, and the importance behind parent education. The studies analyzed demonstrate that there are higher rates of refusal in birth centers and home births as opposed to hospital births. Alternative methods studied, such as breast feeding and mother supplementation, have not been shown to be an equivalent to the IM injection, however, there is promising research regarding an oral method of Vitamin K administration. Based on the research conducted, it is imperative that providers ensure proper patient education throughout the entire pregnancy regarding screenings and preventions, such as a Vitamin K injection and what it prevents, so that parents can make informed decisions when their child is born
How Has COVID-19 Affected Our Orthopedic Implant Industry Partners? Implications for the Surgeon-Industry Relationship in 2020 and Beyond
This article is made available for unrestricted research re-use and secondary analysis in any form or by any means with acknowledgement of the original source. These permissions are granted for the duration of the World Health Organization (WHO) declaration of COVID-19 as a global pandemic.Background
The COVID-19 pandemic has had far-reaching societal and financial consequences. The purpose of this study was to evaluate how COVID-19 has affected AAHKS industry partners and the surgeon-industry relationship, emphasizing education, resource allocation, and strategic direction for the 2nd half of 2020.
Methods
AAHKS industry partners were contacted to participate in a blinded survey and optional interview with the AAHKS Industry Relations Committee. Based on the results, a group of AAHKS member surgeons with disparate practice types were asked to postulate on how the COVID-19 pandemic has and will affect their practice and relationship with Industry.
Results
AAHKS industry partner responses indicated decreased resource allocation for regional, “other national,” and AAHKS annual meetings (67%, 55%, and 30%, respectively). Web-based educational content was expected to increase in 2020 and will likely remain a point of emphasis in 2021 (100% and 70% of responders). For Q3/Q4 2020, a significant emphasis was placed on site of service/outpatient TJA and COVID-19-related safety measures (70% and 90% of responders), as well as increased availability of instrumentation and implants (40% and 60%, respectively).
Conclusion
The COVID-19 pandemic has altered the orthopedic landscape for the foreseeable future. Survey responses by AAHKS industry partners demonstrate a continued commitment to surgeon education with and increasing shift to a web-based platform. Increased resource allocation for outpatient TJA and COVID-19-related safety measures were significant. Articulating optimal mechanisms to aid industry in supporting surgeons with different practice models to meet demand during the second half of fiscal year 2020 will be critical
ROSAT Evidence for Intrinsic Oxygen Absorption in Cooling Flow Galaxies and Groups
Using spatially resolved, deprojected ROSAT PSPC spectra of 10 of the
brightest cooling flow galaxies and groups with low Galactic column densities
we have detected intrinsic absorption over energies ~0.4-0.8 keV in half of the
sample. Since no intrinsic absorption is indicated for energies below ~0.4 keV,
the most reasonable model for the absorber is collisionally ionized gas at
temperatures T=10^{5-6} K with most of the absorption arising from ionized
states of oxygen but with a significant contribution from carbon and nitrogen.
The soft X-ray emission of this warm gas can explain the sub-Galactic column
densities of cold gas inferred within the central regions of most of the
systems. Attributing the absorption to ionized gas reconciles the large columns
of cold H and He inferred from EINSTEIN and ASCA with the lack of such columns
inferred from ROSAT. Within the central ~10-20 kpc, where the constraints are
most secure, the estimated mass of the ionized absorber is consistent with most
(perhaps all) of the matter deposited by a cooling flow over the lifetime of
the flow. Since the warm absorber produces no significant H or He absorption
the large absorber masses are consistent with the negligible atomic and
molecular H inferred from HI and CO observations of cooling flows. It is also
found that if T > ~2x10^5 K then the optical and UV emission implied by the
warm gas does not violate published constraints. Finally, we discuss how the
prediction of warm ionized gas as the product of mass drop-out in these and
other cooling flows can be verified with new CHANDRA and XMM observations.
(Abridged)Comment: 17 pages (5 figures), Accepted for publication in ApJ, expanded
discussion of multiphase spectral models, theoretical implications of warm
gas in cooling flows, and the statistical significance of the oxygen
absorptio
Can GPT-3.5 Generate and Code Discharge Summaries?
Objective: To investigate GPT-3.5 in generating and coding medical documents
with ICD-10 codes for data augmentation on low-resources labels.
Materials and Methods: Employing GPT-3.5 we generated and coded 9,606
discharge summaries based on lists of ICD-10 code descriptions of patients with
infrequent (generation) codes within the MIMIC-IV dataset. Combined with the
baseline training set, this formed an augmented training set. Neural coding
models were trained on baseline and augmented data and evaluated on a MIMIC-IV
test set. We report micro- and macro-F1 scores on the full codeset, generation
codes, and their families. Weak Hierarchical Confusion Matrices were employed
to determine within-family and outside-of-family coding errors in the latter
codesets. The coding performance of GPT-3.5 was evaluated both on prompt-guided
self-generated data and real MIMIC-IV data. Clinical professionals evaluated
the clinical acceptability of the generated documents.
Results: Augmentation slightly hinders the overall performance of the models
but improves performance for the generation candidate codes and their families,
including one unseen in the baseline training data. Augmented models display
lower out-of-family error rates. GPT-3.5 can identify ICD-10 codes by the
prompted descriptions, but performs poorly on real data. Evaluators note the
correctness of generated concepts while suffering in variety, supporting
information, and narrative.
Discussion and Conclusion: GPT-3.5 alone is unsuitable for ICD-10 coding.
Augmentation positively affects generation code families but mainly benefits
codes with existing examples. Augmentation reduces out-of-family errors.
Discharge summaries generated by GPT-3.5 state prompted concepts correctly but
lack variety, and authenticity in narratives. They are unsuitable for clinical
practice.Comment: 15 pages; 250 words in abstract; 3,929 words in main body; 2 figures
(0 black and white, 2 colour); 4 tables; 34 reference
The Extended Blue Continuum and Line Emission around the Central Radio Galaxy in Abell 2597
We present results from detailed imaging of the centrally dominant radio
elliptical galaxy in the cooling flow cluster Abell 2597, using data obtained
with the Wide Field and Planetary Camera 2 (WFPC2) on the Hubble Space
Telescope (HST). This object is one of the archetypal "blue-lobed" cooling flow
radio elliptical galaxies, also displaying a luminous emission-line nebula, a
compact radio source, and a significant dust lane and evidence of molecular gas
in its center. We show that the radio source is surrounded by a complex network
of emission-line filaments, some of which display a close spatial association
with the outer boundary of the radio lobes. We present a detailed analysis of
the physical properties of ionized and neutral gas associated with the radio
lobes, and show that their properties are strongly suggestive of direct
interactions between the radio plasma and ambient gas. We resolve the blue
continuum emission into a series of knots and clumps, and present evidence that
these are most likely due to regions of recent star formation. We investigate
several possible triggering mechanisms for the star formation, including direct
interactions with the radio source, filaments condensing from the cooling flow,
or the result of an interaction with a gas-rich galaxy, which may also have
been responsible for fueling the active nucleus. We propose that the properties
of the source are plausibly explained in terms of accretion of gas by the cD
during an interaction with a gas-rich galaxy, which combined with the fact that
this object is located at the center of a dense, high-pressure ICM can account
for the high rates of star formation and the strong confinement of the radio
source.Comment: Astrophysical Journal, in press, 34 pages, includes 6 PostScript
figures. Latex format, uses aaspp4.sty and epsf.sty file
On the Internal Absorption of Galaxy Clusters
A study of the cores of galaxy clusters with the Einstein SSS indicated the
presence of absorbing material corresponding to 1E+12 Msun of cold cluster gas,
possibly resulting from cooling flows. Since this amount of cold gas is not
confirmed by observations at other wavelengths, we examined whether this excess
absorption is present in the ROSAT PSPC observations of 20 bright galaxy
clusters. For 3/4 of the clusters, successful spectral fits were obtained with
absorption due only to the Galaxy, and therefore no extra absorption is needed
within the clusters, in disagreement with the results from the Einstein SSS
data for some of the same clusters. For 1/4 of the clusters, none of our
spectral fits was acceptable, suggesting a more complicated cluster medium than
the two-temperature and cooling flow models considered here. However, even for
these clusters, substantial excess absorption is not indicated.Comment: accepted by the Astrophysical Journa
Formation of Low Mass Stars in Elliptical Galaxy Cooling Flows
X-ray emission from hot (T = 10^7 K) interstellar gas in massive elliptical
galaxies indicates that 10^{10} M_sun has cooled over a Hubble time, but
optical and radio evidence for this cold gas is lacking. We provide detailed
theoretical support for the hypothesis that this gas has formed into low
luminosity stars. Within several kpc of the galactic center, interstellar gas
first cools to T = 10^4 K where it is heated by stellar UV and emits the
observed diffuse optical line emission. This cooling occurs at a large number
(10^6) of isolated sites. After less than a solar mass of gas has accumulated
(10^{-6} M_sun/yr) at a typical cooling site, a neutral (HI or H_2) core
develops in the HII cloud where gas temperatures drop to T = 15 K and the
ionization level (from thermal X-rays) is very low (x = 10^{-6}). We show that
the maximum mass of cores that become gravitationally unstable is only about 2
M_sun. No star can exceed this mass. Fragmentation of collapsing cores produces
a population of low mass stars with a bottom-heavy IMF and radial orbits.
Gravitational collapse and ambipolar diffusion are rapid. The total mass of
star-forming (dust-free) HI or H_2 cores in a typical bright elliptical is only
10^6 M_sun, below current observational thresholds.Comment: 23 pages in AASTEX LaTeX with 8 figures; accepted by Astrophysical
Journa
OMEN-SED 1.0: a novel, numerically efficient organic matter sediment diagenesis module for coupling to Earth system models
We present the first version of
OMEN-SED (Organic Matter ENabled SEDiment model), a new, one-dimensional
analytical early diagenetic model resolving organic matter cycling and
the associated biogeochemical dynamics in marine sediments designed to be coupled
to Earth system models. OMEN-SED explicitly describes organic matter
(OM) cycling and the associated dynamics of the most important
terminal electron acceptors (i.e. O2, NO3, SO4) and
methane (CH4), related reduced substances (NH4, H2S),
macronutrients (PO4) and associated pore water quantities
(ALK, DIC). Its reaction network accounts for the most
important primary and secondary redox reactions, equilibrium reactions,
mineral dissolution and precipitation, as well as adsorption and desorption
processes associated with OM dynamics that affect the dissolved and solid
species explicitly resolved in the model. To represent a redox-dependent
sedimentary P cycle we also include a representation of the formation and
burial of Fe-bound P and authigenic Ca–P minerals. Thus, OMEN-SED is able to
capture the main features of diagenetic dynamics in marine sediments and
therefore offers similar predictive abilities as a complex, numerical
diagenetic model. Yet, its computational efficiency allows for its coupling to
global Earth system models and therefore the investigation of coupled global
biogeochemical dynamics over a wide range of climate-relevant timescales.
This paper provides a detailed description of the new sediment model, an
extensive sensitivity analysis and an evaluation of OMEN-SED's
performance through comprehensive comparisons with observations and results
from a more complex numerical model. We find that solid-phase and dissolved pore
water profiles for different ocean depths are reproduced with good accuracy
and simulated terminal electron acceptor fluxes fall well within the range of
globally observed fluxes. Finally, we illustrate its application in an Earth
system model framework by coupling OMEN-SED to the Earth system model cGENIE
and tune the OM degradation rate constants to optimise the fit of simulated
benthic OM contents to global observations. We find that the simulated sediment
characteristics of the coupled model framework, such as OM degradation rates,
oxygen penetration depths and sediment–water interface fluxes, are generally
in good agreement with observations and in line with what one would expect on
a global scale. Coupled to an Earth system model, OMEN-SED is thus a powerful
tool that will not only help elucidate the role of benthic–pelagic exchange
processes in the evolution and the termination of a wide
range of climate events, but will also allow for a direct comparison of model
output with the sedimentary record – the most important climate archive on
Earth.</p
Long-Term Survival after Gamma Knife Radiosurgery in a Case of Recurrent Glioblastoma Multiforme: A Case Report and Review of the Literature
The management of recurrent glioblastoma is highly challenging, and treatment outcomes remain uniformly poor. Glioblastoma is a highly infiltrative tumor, and complete surgical resection of all microscopic extensions cannot be achieved at the time of initial diagnosis, and hence local recurrence is observed in most patients. Gamma Knife radiosurgery has been used to treat these tumor recurrences for select cases and has been successful in prolonging the median survival by 8–12 months on average for select cases. We present the unique case of a 63-year-old male with multiple sequential recurrences of glioblastoma after initial standard treatment with surgery followed by concomitant external beam radiation therapy and chemotherapy (temozolomide). The patient was followed clinically as well as with surveillance MRI scans at every 2-3-month intervals. The patient underwent Gamma Knife radiosurgery three times for 3 separate tumor recurrences, and the patient survived for seven years following the initial diagnosis with this aggressive treatment. The median survival in patients with recurrent glioblastoma is usually 8–12 months after recurrence, and this unique case illustrates that aggressive local therapy can lead to long-term survivors in select situations. We advocate that each patient treatment at the time of recurrence should be tailored to each clinical situation and desire for quality of life and improved longevity
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