Search

The Devonian-Carboniferous transition marks a fundamental shift in the surface environment primarily related to changes in ocean-atmosphere oxidation states 1,2 , resulting from the continued proliferation of vascular land plants that stimulated the hydrological cycle and continental weathering 3,4 , glacioeustasy 5,6 , eutrophication and anoxic expansion in epicontinental seas 3,4 , and mass extinction events 2,7,8 . Here we present a comprehensive spatial and temporal compilation of geochemical data from 90 cores across the entire Bakken Shale (Williston Basin, North America). Our dataset allows for the detailed documentation of stepwise transgressions of toxic euxinic waters into the shallow oceans that drove a series of Late Devonian extinction events. Other Phanerozoic extinctions have also been related to the expansion of shallow-water euxinia, indicating that hydrogen sulfide toxicity was a key driver of Phanerozoic biodiversity., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Whiting events-the episodic precipitation of fine-grained suspended calcium carbonates in the water column-have been documented across a variety of marine and lacustrine environments. Whitings likely are a major source of carbonate muds, a constituent of limestones, and important archives for geochemical proxies of Earth history. While several biological and physical mechanisms have been proposed to explain the onset of these precipitation events, no consensus has been reached thus far. Fayetteville Green Lake (New York, USA) is a meromictic lake that experiences annual whitings. Materials suspended in the water column collected through the whiting season were characterized using scanning electron microscopy and scanning transmission X-ray microscopy. Whitings in Fayetteville Green Lake are initiated in the spring within the top few meters of the water column, by precipitation of fine amorphous calcium carbonate (ACC) phases nucleating on microbial cells, as well as on abundant extracellular polymeric substances (EPS) frequently associated with centric diatoms. Whiting particles found in the summer consist of 5-7 μm calcite grains forming aggregates with diatoms and EPS. Simple calculations demonstrate that calcite particles continuously grow over several days, then sink quickly through the water column. In the late summer, partial calcium carbonate dissolution is observed deeper in the water column. Settling whiting particles, however, reach the bottom of the lake, where they form a major constituent of the sediment, along with diatom frustules. The role of diatoms and associated EPS acting as nucleation surfaces for calcium carbonates is described for the first time here as a potential mechanism participating in whitings at Fayetteville Green Lake. This mechanism may have been largely overlooked in other whiting events in modern and ancient environments., (© 2022 The Authors. Geobiology published by John Wiley & Sons Ltd.)

Biogeochemical cycling of sulfur is relatively understudied in terrestrial environments compared to marine environments. However, the comparative ease of access, observation, and sampling of terrestrial settings can expand our understanding of organisms and processes important in the modern sulfur cycle. Furthermore, these sites may allow for the discovery of useful process analogs for ancient sulfur-metabolizing microbial communities at times in Earth's past when atmospheric O 2 concentrations were lower and sulfide was more prevalent in Earth surface environments. We identified a new site at Santa Paula Creek (SPC) in Ventura County, CA-a remarkable freshwater, gravel-bedded mountain stream charged with a range of oxidized and reduced sulfur species and heavy hydrocarbons from the emergence of subsurface fluids within the underlying sulfur- and organic-rich Miocene-age Monterey Formation. SPC hosts a suite of morphologically distinct microbial biofacies that form in association with the naturally occurring hydrocarbon seeps and sulfur springs. We characterized the geology, stream geochemistry, and microbial facies and diversity of the Santa Paula Creek ecosystem. Using geochemical analyses and 16S rRNA gene sequencing, we found that SPC supports a dynamic sulfur cycle that is largely driven by sulfide-oxidizing microbial taxa, with contributions from smaller populations of sulfate-reducing and sulfur-disproportionating taxa. This preliminary characterization of SPC revealed an intriguing site in which to study geological and geochemical controls on microbial community composition and to expand our understanding of sulfur cycling in terrestrial environments., (© 2022 John Wiley & Sons Ltd.)

D. Jablonski [ Proc. Natl. Acad. Sci. U.S.A. 99, 8139-8144 (2002)] coined the term "dead clades walking" (DCWs) to describe marine fossil orders that experience significant drops in genus richness during mass extinction events and never rediversify to previous levels. This phenomenon is generally interpreted as further evidence that the macroevolutionary consequences of mass extinctions can continue well past the formal boundary. It is unclear, however, exactly how long DCWs are expected to persist after extinction events and to what degree they impact broader trends in Phanerozoic biodiversity. Here we analyze the fossil occurrences of 134 skeletonized marine invertebrate orders in the Paleobiology Database (paleobiodb.org) using a Bayesian method to identify significant change points in genus richness. Our analysis identifies 70 orders that experience major diversity losses without recovery. Most of these taxa, however, do not fit the popular conception of DCWs as clades that narrowly survive a mass extinction event and linger for only a few stages before succumbing to extinction. The median postdrop duration of these DCW orders is long (>30 Myr), suggesting that previous studies may have underestimated the long-term taxonomic impact of mass extinction events. More importantly, many drops in diversity without recovery are not associated with mass extinction events and occur during background extinction stages. The prevalence of DCW orders throughout both mass and background extinction intervals and across phyla (>50% of all marine invertebrate orders) suggests that the DCW pattern is a major component of macroevolutionary turnover., Competing Interests: The authors declare no competing interest.

Objective: To compare complication rates, perioperative outcomes, and survival after radical cystectomy (RC) in patients with prior abdominal or pelvic radiation therapy (RT) vs those without an RT history., Materials and Methods: We retrospectively reviewed patients undergoing RC for urothelial carcinoma between January 2008 and January 2016. Patients were stratified by receipt of RT, and differences in complications (any, minor, and major) at 30 and 90 days, as well as estimated blood loss, length of surgery, length of hospital stay, and pathologic stage, were compared. Recurrence-free, cancer-specific, and overall survival were compared using the Kaplan-Meier method and log-rank test., Results: We identified 518 patients who underwent RC between 2008 and 2016. Of these patients, 55 (11%) had a history of RT. There were no significant differences in complication rates (66% vs 69%, P= .80) between patients who did not and patients who did have a history of RT. Similarly, there were no differences in any perioperative or pathologic outcome by receipt of prior RT (all P>.05). Meanwhile, at a median follow-up of 26 (interquartile range 13-46) months among patients alive at last follow-up, no differences in survival were observed by prior RT (P= .08)., Conclusion: Among patients with a history of prior abdominal or pelvic RT treated at a tertiary referral center, there was no difference in complication rates, perioperative, or pathologic outcomes. Importantly, no differences in survival were noted by prior RT receipt. Therefore, our data support the use of RC, when indicated, in patients with a prior history of abdominal or pelvic RT., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Use of furrow irrigation in row crop production is a common practice through much of the Midsouth US and yet, nutrients can be transported off-site through surface runoff. A field study with cotton (Gossypium hirsutum, L.) was conducted to understand the impact of furrow tillage practices and nitrogen (N) fertilizer placement on characteristics of runoff water quality during the growing season. The experiment was designed as a randomized complete block design with conventional (CT) and conservation furrow tillage (FT) in combination with either urea (URN) broadcast or 32% urea ammonium nitrate (UAN) injected, each applied at 101kgNha -1 . Concentrations of ammonium (NH 4 -N), nitrate (NO 3 -N), nitrite (NO 2 -N), and dissolved phosphorus (P) in irrigation runoff water and lint yields were measured in all treatments. The intensity and chemical form of nutrient losses were primarily controlled by water runoff volume and agronomic practice. Across tillage and fertilizer N treatments, median N concentrations in the runoff were <0.3mgNL -1 , with NO 3 -N being relatively the highest among N forms. Concentrations of runoff dissolved P were <0.05mgPL -1 and were affected by volume of runoff water. Water pH, specific electrical conductivity, alkalinity and hardness were within levels that common to local irrigation water and less likely to impair pollution in waterways. Lint yields averaged 1111kgha -1 and were higher (P-value=0.03) in FT compared to CT treatments. Runoff volumes across irrigation events were greater (P-value=0.02) in CT than FT treatments, which increased NO 3 -N mass loads in CT treatments (394gNO 3 -Nha -1 season -1 ). Nitrate-N concentrations in CT treatments were still low and pose little threat to N contaminations in waterways. The findings support the adoption of conservation practices for furrow tillage and N fertilizer placement that can reduce nutrient runoff losses in furrow irrigation systems., (Published by Elsevier B.V.)

Exercise provides cardioprotection against ischemia-reperfusion injury, a process involving mitochondrial reactive oxygen species (ROS) generation and calcium overload. This study tested the hypotheses that isolated mitochondria from hearts of endurance-trained rats have decreased ROS production and improved tolerance against Ca(2+)-induced dysfunction. Male Fischer 344 rats were either sedentary (Sed, n = 8) or endurance exercise trained (ET, n = 11) by running on a treadmill for 16 wk (5 days/wk, 60 min/day, 25 m/min, 6 degrees grade). Mitochondrial oxidative phosphorylation measures were determined with glutamate-malate or succinate as substrates, and H(2)O(2) production and permeability transition pore (PTP) opening were determined with succinate. All assays were carried out in the absence and presence of calcium. In response to 25 and 50 microM CaCl(2), Sed and ET displayed similar decreases in state 3 respiration, respiratory control ratio, and ADP:O ratio. Ca(2+)-induced PTP opening was also similar. However, H(2)O(2) production by ET was lower than Sed (P < 0.05) in the absence of calcium (323 +/- 12 vs. 362 +/- 11 pmol.min(-1).mg protein(-1)) and the presence of 50 microM CaCl(2) (154 +/- 3 vs. 197 +/- 7 pmol.min(-1).mg protein(-1)). Rotenone, which blocks electron flow from succinate to complex 1, reduced H(2)O(2) production and eliminated differences between ET and Sed. Mitochondrial superoxide dismutase and glutathione peroxidase were not affected by exercise. Catalase activity was extremely low but increased 49% in ET (P < 0.05). In conclusion, exercise reduces ROS production in myocardial mitochondria through adaptations specific to complex 1 but does not improve mitochondrial tolerance to calcium overload.

Thirty-seven patients with severe head injury underwent radionuclide cisternography to detect early and late effects of trauma on cerebrospinal fluid (CSF) circulation. Thirty-one patients had subdural hematomas or hygromas and six had cerebral contusions without extracerebral masses. Cisternographic results were abnormal in 23 patients with subdural masses and normal in five who had only cerebral contusions. Of eight patients undergoing serial studies, one had persistent partial obstruction, five had partial resolution of abnormalities, and the two with progressive obstruction had their conditions improved by shunting. Angiography suggested transtentorial herniation in 11 patients with cisternal block, six of whom had clinical signs of herniation on the same side.

A new radionuclide tomographic scanner produces 12 tomographic brain images instead of a single conventional brain scan. This scanner has important advantages over conventional radionuclide scanning. The size, shape, and extent of a lesion and its relationship to surrounding structures are better defined. Tomography often permits a firm diagnostic impression in studies that would be equivocal with the use of routine scanning. Tomography may also be used in conjunction with radionuclide cisternography to provide a clear visualization of the CSF pathways and ventricles and to distinguish overlying structures.

Radionuclide angiography, using high resolution equipment, is a sensitive noninvasive, safe, and rapid diagnostic test for ischemia of the anterior circulation of the brain. The test permits recognition of focally increased or decreased circulation immediately following the onset of a neurologic deficit. The sensitivity of the test is improved by using multiple projections of the head. The distribution of the anterior cerebral artery is best seen in the anterior projection; the lateral projection is used to resolve the superior and inferior divisions of the middle cerebral artery or to identify multiple regions of ischemia. Both projections should be used routinely.

This article describes the clinical application of the 80-lens optical camera in the diagnosis of cerebral infarction, subdural hematoma, intracranial tumor, and hydrocephalus. The 80-lens camera is a simple noncomputerized addition to the Anger scintillation camera that permits an estimation of the cerebral blood flow. The study is noninvasive and quick, minimizing the effect of movement artifact and showing areas of either increased or decreased blood flow. Abnormal tumor vessels appear, and subdural hematomas show brain displacement away from the skull edge. Interpretation of blood flow pattern is not affected by scalp or skull trauma, eliminating a source of error incurred with static scans.

Abnormal distribution of cerebral vascular flow was studied in a patient who had a traumatic carotid-cavernous sinus fistula. Serial studies were performed using a method for determining relative cerebral vascular flow:99mtechnetium-diethylenetriamine pentaacetic acid (99mTc-DTPA) was injected intravenously and flow data were processed by a digital computer. Serial studies documented the occurrence of a vascular "steal" during temporary carotid occlusion; postoperative studies showed disappearance of the steal and obliteration of thiling arterial structures and capillary filling in the brain, and in demonstrating alteration in the cerebral circulation.

A self-report scale was constructed and validated that measures individual differences in objectivism--the tendency to base one's judgments and beliefs on empirical information and rational considerations. Validity data showed that, compared to people who score low on the Objectivism Scale, highly objective individuals enjoy thinking more, rely more on observable facts when making decisions, and place less emphasis on subjective and intuitive styles of decision making. Among graduate students in psychology, objectivism correlated positively with ratings of research-oriented careers, but negatively with ratings of mental health careers; also, highly objective students were more critical of nonobjective psychological assessment techniques and placed greater importance on research. Objectivism also predicted preferences for newspaper articles, college course selections, and the criteria respondents use when making decisions.

Two cases of superior sagittal sinus thrombosis were diagnosed using a new technique of dynamic radionuclide brain-imaging. With the patient's head in the posterior oblique position, and 80-lens optical camera records the appearance of radionuclides in the superior sagittal sinus. This technique is quick and noninvasive, and serial studies are easily performed. Dural sinus thrombosis is difficult to diagnose on clinical findings alone. Dynamic canning should be used to screen high risk patients, such as those having pseudotumor syndrome or clotting disorders and elderly patients having pulmonary emboli or unexplained deterioration of mental status.