Hydroclimatic Black Swans: Characterization of the Oceanic and Atmospheric Drivers of Spatially Widespread Droughts in North America

Droughts that achieve extreme spatial extent over the contiguous United States pose unique challenges because of their potential to strain multiple water resources simultaneously. Two such spatially coherent, reoccurring droughts are (i) those that span the majority of the US (herein pan-CONUS droughts) and (ii) those that span the US Pacific coast (herein pan-coastal droughts). These droughts can have drastic impacts on US agriculture, water resources, and wildfire risk, thus posing serious risks to our food security, infrastructure, and economy. Such events are difficult to characterize due to the relatively short instrumental record and the rarity of observed widespread drought. The combined availability of observations, ensembles of climate model simulations, and high-resolution paleoclimate reconstructions, however, have recently increased the sampling and length of the hydroclimate record. This wealth of climate data makes the time ripe to investigate the causes and dynamics of spatially widespread droughts, with implications for their impacts in the future under a changing climate. Previous studies have established the sensitivity of North American drought variability to large-scale atmosphere-ocean modes. In particular, the El Niño Southern Oscillation (ENSO) and Atlantic Multidecadal Oscillation (AMO) have been linked with widespread drying over the United States. While neither mode alone is likely to cause either pan-CONUS or pan-coastal droughts, the canonical understanding of oceanic influences on North American hydroclimate nevertheless suggest that (i) pan-CONUS droughts are forced by a contemporaneous cold tropical Pacific Ocean and a warm tropical Atlantic Ocean and (ii) pan-coastal droughts are forced by cold tropical and north Pacific conditions. By examining how pan-CONUS and pan-coastal droughts are represented in climate model simulations and comparing them against observation and paleoclimate reconstructions, the work in this dissertation tests the above-mentioned canonical understanding. For pan-CONUS droughts, SST forcing is shown to originate almost entirely from La Niña conditions, with little contribution from the tropical Atlantic. Furthermore, internal atmospheric variability influences pan-CONUS drought occurrence by as much or more than ocean forcing and can alone cause pan-CONUS droughts. Internal atmospheric variability is shown to play an even larger, predominant role in driving pan-coastal droughts, accounting for upwards of 80% of the severity of the events; cold Pacific conditions, while playing a clearly detectable role, are only secondary in their influence relative to internal atmospheric variability. These results are then compared to the observational and/or paleoclimate record, which supports the model-inferred conclusions. Collectively, the work outlined in this dissertation holds important implications regarding (i) mechanistic understandings of North American hydroclimate, (ii) predictability, or lack thereof, of pan-CONUS and pan-coastal droughts, and (iii) how pan-CONUS and pan-costal droughts may change in the future due to increases in greenhouse gas emissions. The research contained herein furthermore demonstrates the precise extent to which large-scale ocean-atmosphere and internal atmospheric variability interact. In so doing, this dissertation contributes to a fundamental understanding of the importance of large-scale ocean-atmosphere modes relative to internal atmospheric variability in North American hydroclimate dynamics

Total joint reconstruction using computer-assisted surgery with stock prostheses for a patient with bilateral TMJ ankylosis

Backgrounds The purpose of this study is to discuss the total joint reconstruction surgery for a patient with recurrent ankylosis in bilateral temporomandibular joints (TMJs) using three-dimensional (3D) virtual surgical planning, computer-aided manufacturing (CAD/CAM)-fabricated surgical guides, and stock TMJ prostheses. Case presentation A 66-year-old female patient, who had a history of multiple TMJ surgeries, complained of severe difficulty in eating and trismus. The 3D virtual surgery was performed with a virtual surgery software (FACEGIDE, MegaGen implant, Daegu, South Korea). After confirmation of the location of the upper margin for resection of the root of the zygoma and the lower margin for resection of the ankylosed condyle, and the position of the fossa and condyle components of stock TMJ prosthesis (Biomet, Jacksonville, FL, USA), the surgical guides were fabricated with CAD/CAM technology. Under general anesthesia, osteotomy and placement of the stock TMJ prosthesis (Biomet) were carried out according to the surgical planning. At 2 months after the operation, the patient was able to open her mouth up to 30 mm without complication. Conclusion For a patient who has recurrent ankylosis in bilateral TMJs, total joint reconstruction surgery using 3D virtual surgical planning, CAD/CAM-fabricated surgical guides, and stock TMJ prostheses may be an effective surgical treatment option

Patterns of inflammatory immune responses in patients with septic shock receiving vitamin C, hydrocortisone, and thiamine: clustering analysis in Korea

Background Sepsis is characterized by heterogeneous immune responses that may evolve during the course of illness. This study identified inflammatory immune responses in septic patients receiving vitamin C, hydrocortisone, and thiamine. Methods This was a single-center, post-hoc analysis of 95 patients with septic shock who received the vitamin C protocol. Blood samples were drawn on days 1–2, 3–4, and 6–8 after shock onset. Group-based multi-trajectory modeling was used to identify immune trajectory groups. Results The median age was 78 years (interquartile range, 70–84 years), and 56% were male. Clustering analysis identified group 1 (n=41), which was characterized by lower interleukin (IL)-6, tumor necrosis factor (TNF)-α, and IL-10 levels, and these levels remained stationary or mildly increased until day 7. Conversely, group 2 (n=54) expressed initially higher IL-6, TNF-α, and IL-10 levels that decreased rapidly by day 4. There was a nonsignificant increase in lymphocyte count and a decrease in C-reactive protein level until day 7 in group 2. The intensive care unit mortality rate was significantly lower in group 2 (39.0% vs. 18.5%, P=0.03). Group 2 also had a significantly higher decrease in the mean (standard deviation) vasopressor dose (norepinephrine equivalent: –0.09±0.16 μg/kg/min vs. –0.23±0.31 μg/kg/min, P<0.001) and Sequential Organ Failure Assessment score (0±5 vs. –4±3, P=0.002) between days 1 and 4. Conclusions There may be different subphenotypes in septic patients receiving the vitamin C protocol

An Atmospheric Bridge Between the Subpolar and Tropical Atlantic Regions: A Perplexing Asymmetric Teleconnection

The largest sea surface temperature (SST) anomalies associated with Atlantic Multidecadal Variability (AMV) occur over the Atlantic subpolar gyre, yet it is the tropical Atlantic from where the global impacts of AMV originate. Processes that communicate SST change from the subpolar Atlantic gyre to the tropical North Atlantic thus comprise a crucial mechanism of AMV. Here we use idealized model experiments to show that such communication is accomplished by an “atmospheric bridge.” Our results demonstrate an unexpected asymmetry: the atmosphere is effective in communicating cold subpolar SSTs to the north tropical Atlantic, via an immediate extratropical atmospheric circulation change that invokes slower wind-driven evaporative cooling along the Eastern Atlantic Basin and into the tropics. Warm subpolar SST anomalies do not elicit a robust tropical Atlantic response. Our results highlight a key dynamical feature of AMV for which warm and cold phases are not opposites

Is it Possible to Successfully Treat Locally Advanced Colon Cancer Using Pre-Operative Chemoradiotherapy?

Pre-operative chemoradiotherapy (CRT) is a preferable treatment option for patients with locally advanced rectal cancer. However, few data are available regarding pre-operative CRT for locally advanced colon cancer. Here, we describe two cases of successful treatment with pre-operative CRT and establish evidence supporting this treatment option in patients with locally advanced colon cancer. In the first case, a 65-year-old woman was diagnosed with ascending colon cancer with duodenal invasion. In the second case, a 63-year-old man was diagnosed with a colonic-duodenal fistula due to transverse colon cancer invasion. These case reports will help to establish a treatment consensus for pre-operative CRT in patients with locally advanced colon cancer

Characterization of Drug-Resistant Lipid-Dependent Differentially Detectable Mycobacterium tuberculosis

An estimated 15-20% of patients who are treated for pulmonary tuberculosis (TB) are culture-negative at the time of diagnosis. Recent work has focused on the existence of differentially detectable Mycobacterium tuberculosis (Mtb) bacilli that do not grow under routine solid culture conditions without the addition of supplementary stimuli. We identified a cohort of TB patients in Lima, Peru, in whom acid-fast bacilli could be detected by sputum smear microscopy, but from whom Mtb could not be grown in standard solid culture media. When we attempted to re-grow Mtb from the frozen sputum samples of these patients, we found that 10 out of 15 could be grown in a glycerol-poor/lipid-rich medium. These fell into the following two groups: a subset that could be regrown in glycerol after lipid-resuscitation , and a group that displayed a heritable glycerol-sensitive phenotype that were unable to grow in the presence of this carbon source. Notably, all of the glycerol-sensitive strains were found to be multidrug resistant. Although whole-genome sequencing of the lipid-resuscitated strains identified 20 unique mutations compared to closely related strains, no single genetic lesion could be associated with this phenotype. In summary, we found that lipid-based media effectively fostered the growth of Mtb from a series of sputum smear-positive samples that were not culturable in glycerol-based Lowenstein-Jensen or 7H9 media, which is consistent with Mtb\u27s known preference for non-glycolytic sources during infection. Analysis of the recovered strains demonstrated that both genetic and non-genetic mechanisms contribute to the observed differential capturability, and suggested that this phenotype may be associated with drug resistance

Transient cortical blindness after heart surgery in a child patient -A case report-

Visual loss occurring after pediatric cardiac surgery employing cardiopulmonary bypass (CPB) is relatively rare but the risk is substantial. Compromised cerebral perfusion due to a CPB related micro-embolization and inflammatory vascular changes as well as reduced oxygen carrying capacity in hemodilution and hypothermia during CPB might be major contributing factors to the development of postoperative visual loss after cardiac surgery with CPB. A case of immediate but transient postoperative visual loss was encountered in a 21-month-old male who underwent tricuspid valve surgery. Despite routine intraoperative measures to maintain an adequate perfusion pressure throughout the procedure, postoperative computed tomography revealed a subacute infarct in his occipital lobe. Recovery began on postoperative day 28, and the patient's vision was restored by 31 days

Changing hydroclimate dynamics and the 19th to 20th century wetting trend in the English Channel region of northwest Europe

Northwestern Europe has experienced a trend of increasingly wet winters over the past 150 years, with few explanations for what may have driven this hydroclimatic change. Here we use the Old World Drought Atlas (OWDA), a tree-ring based reconstruction of the self-calibrating Palmer Drought Severity Index (scPDSI), to examine this wetting trend and place it in a longer hydroclimatic context. We find that scPDSI variability in northwestern Europe is strongly correlated with the leading mode of the OWDA during the last millennium (1000–2012). This leading mode, here named the ‘English Channel’ (EC) mode, has pronounced variability on interannual to centennial timescales and has an expression in scPDSI similar to that of the East Atlantic teleconnection pattern. A shift in the EC mode from a prolonged negative phase to more neutral conditions during the 19th and 20th centuries is associated with the wetting trend over its area of influence in England, Wales, and much of northern continental Europe. The EC mode is the dominant scPDSI mode from approximately 1000–1850, after which its dominance waned in favor of the secondary ‘North–South’ (NS) mode, which has an expression in scPDSI similar to that of the winter North Atlantic Oscillation (NAO). We examine the dynamical nature of both of these modes and how they vary on interannual to centennial timescales. Our results provide insight into the nature of hydroclimate variability in Europe before the widespread availability of instrumental observations

Common Variants in the Glycerol Kinase Gene Reduce Tuberculosis Drug Efficacy

Despite the administration of multiple drugs that are highly effective in vitro, tuberculosis (TB) treatment requires prolonged drug administration and is confounded by the emergence of drug-resistant strains. To understand the mechanisms that limit antibiotic efficacy, we performed a comprehensive genetic study to identify Mycobacterium tuberculosis genes that alter the rate of bacterial clearance in drug-treated mice. Several functionally distinct bacterial genes were found to alter bacterial clearance, and prominent among these was the glpK gene that encodes the glycerol-3-kinase enzyme that is necessary for glycerol catabolism. Growth on glycerol generally increased the sensitivity of M. tuberculosis to antibiotics in vitro, and glpK-deficient bacteria persisted during antibiotic treatment in vivo, particularly during exposure to pyrazinamide-containing regimens. Frameshift mutations in a hypervariable homopolymeric region of the glpK gene were found to be a specific marker of multidrug resistance in clinical M. tuberculosis isolates, and these loss-of-function alleles were also enriched in extensively drug-resistant clones. These data indicate that frequently observed variation in the glpK coding sequence produces a drug-tolerant phenotype that can reduce antibiotic efficacy and may contribute to the evolution of resistance. IMPORTANCE: TB control is limited in part by the length of antibiotic treatment needed to prevent recurrent disease. To probe mechanisms underlying survival under antibiotic pressure, we performed a genetic screen for M. tuberculosis mutants with altered susceptibility to treatment using the mouse model of TB. We identified multiple genes involved in a range of functions which alter sensitivity to antibiotics. In particular, we found glycerol catabolism mutants were less susceptible to treatment and that common variation in a homopolymeric region in the glpK gene was associated with drug resistance in clinical isolates. These studies indicate that reversible high-frequency variation in carbon metabolic pathways can produce phenotypically drug-tolerant clones and have a role in the development of resistance

A quantitative hydroclimatic context for the European Great Famine of 1315-17

The European Great Famine of 1315–1317 triggered one of the worst population collapses in European history and ranks as the single worst European famine in mortality as a proportion of population. Historical records point to torrential rainfall, land saturation, crop failure, and prolonged flooding as important causes of the famine. Here we use the tree-ring based Old World Drought Atlas (OWDA) to show that the average of each growing season preceding the Great Famine years (1314–1316) was the fifth wettest over Europe from 1300 to 2012 C.E. The spatial and temporal characteristics of our OWDA-estimated anomalies are in excellent agreement with available historical accounts. We also characterize a mode of European hydroclimate variability that is associated with the Great Famine, which we term the “Great Famine mode.” This mode emerges as the leading mode of European hydroclimate variability from 1300–2012 and is strongly associated with extreme wet and dry events in Europe over the last millennium