Shadow Molecular Dynamics and Atomic Cluster Expansions for Flexible Charge Models.

A shadow molecular dynamics scheme for flexible charge models is presented where the shadow Born-Oppenheimer potential is derived from a coarse-grained approximation of range-separated density functional theory. The interatomic potential, including the atomic electronegativities and the charge-independent short-range part of the potential and force terms, is modeled by the linear atomic cluster expansion (ACE), which provides a computationally efficient alternative to many machine learning methods. The shadow molecular dynamics scheme is based on extended Lagrangian (XL) Born-Oppenheimer molecular dynamics (BOMD) [Eur. Phys. J. B 2021, 94, 164]. XL-BOMD provides stable dynamics while avoiding the costly computational overhead associated with solving an all-to-all system of equations, which normally is required to determine the relaxed electronic ground state prior to each force evaluation. To demonstrate the proposed shadow molecular dynamics scheme for flexible charge models using atomic cluster expansion, we emulate the dynamics generated from self-consistent charge density functional tight-binding (SCC-DFTB) theory using a second-order charge equilibration (QEq) model. The charge-independent potentials and electronegativities of the QEq model are trained for a supercell of uranium oxide (UO2) and a molecular system of liquid water. The combined ACE+XL-QEq molecular dynamics simulations are stable over a wide range of temperatures both for the oxide and for the molecular systems and provide a precise sampling of the Born-Oppenheimer potential energy surfaces. Accurate ground Coulomb energies are produced by the ACE-based electronegativity model during an NVE simulation of UO2, predicted to be within 1 meV of those from SCC-DFTB on average during comparable simulations.

A new chronology for tsunami deposits prior to the 1700 CE Cascadia earthquake from Vancouver Island, Canada.

Coastal deposits at Tofino, Ucluelet, and Port Alberni in Vancouver Island along the Cascadia subduction zone were re-examined to improve the earthquake history of the southwest coast of Canada. We found sand sheets interbedded within peat and mud, suggesting deposition by strong flows in a low-energy environment. Based on limiting maximum and minimum ages derived from plant macrofossils, the age of one of the sand sheets below the tsunami deposits of the great Cascadia earthquake in 1700 CE was estimated to be 1330-1430 CE. Onshore paleoseismic evidence has been documented in Vancouver Island, northern Washington, and northern Oregon during this period. However, the newly constrained age is between those of coseismic subsidence Y and W events in southern Washington, which have been recognized as the 1700 CE and the penultimate Cascadia earthquakes, respectively. Moreover, the new age partly overlaps with the age of offshore paleoseismic evidence for T2, interpreted to have originated from the penultimate Cascadia earthquake, based on offshore turbidite records. The new chronology prior to the 1700 CE Cascadia tsunami deposit from Vancouver Island contributes to a better understand of the timing of the penultimate Cascadia earthquake.

Did a 3800-year-old Mw ~9.5 earthquake trigger major social disruption in the Atacama Desert?

Early inhabitants along the hyperarid coastal Atacama Desert in northern Chile developed resilience strategies over 12,000 years, allowing these communities to effectively adapt to this extreme environment, including the impact of giant earthquakes and tsunamis. Here, we provide geoarchaeological evidence revealing a major tsunamigenic earthquake that severely affected prehistoric hunter-gatherer-fisher communities ~3800 years ago, causing an exceptional social disruption reflected in contemporary changes in archaeological sites and triggering resilient strategies along these coasts. Together with tsunami modeling results, we suggest that this event resulted from a ~1000-km-long megathrust rupture along the subduction contact of the Nazca and South American plates, highlighting the possibility of Mw ~9.5 tsunamigenic earthquakes in northern Chile, one of the major seismic gaps of the planet. This emphasizes the necessity to account for long temporal scales to better understand the variability, social effects, and human responses favoring resilience to socionatural disasters.

Single-Step Direct Laser Writing of Multimetal Oxygen Evolution Catalysts from Liquid Precursors.

We investigate a laser direct-write method to synthesize and deposit metastable, mixed transition metal oxides and evaluate their performance as oxygen evolution reaction catalysts. This laser processing method enabled the rapid synthesis of diverse heterogeneous alloy and oxide catalysts directly from cost-effective solution precursors, including catalysts with a high density of nanocrystalline metal alloy inclusions within an amorphous oxide matrix. The nanoscale heterogeneous structures of the synthesized catalysts were consistent with reactive force-field Monte Carlo calculations. By evaluating the impact of varying transition metal oxide composition ratios, we created a stable Fe0.63Co0.19Ni0.18Ox/C catalyst with a Tafel slope of 38.23 mV dec-1 and overpotential of 247 mV, a performance similar to that of IrO2. Synthesized Fe0.63Co0.19Ni0.18Ox/C and Fe0.14Co0.46Ni0.40Ox/C catalysts were experimentally compared in terms of catalytic performance and structural characteristics to determine that higher iron content and a less crystalline structure in the secondary matrix decrease the charge transfer resistance and thus is beneficial for electrocatalytic activity. This conclusion is supported by density-functional theory calculations showing distorted active sites in ternary metal catalysts are key for lowering overpotentials for the oxygen evolution reaction.

Effects of surface charge and cluster size on the electrochemical dissolution of platinum nanoparticles using COMB3 and continuum electrolyte models.

We study the site-dependent dissolution of platinum nanoparticles under electrochemical conditions to assess their thermodynamic stability as a function of shape and size using empirical molecular dynamics and electronic-structure models. The third-generation charge optimized many-body potential is employed to determine the validity of uniform spherical representations of the nanoparticles in predicting dissolution potentials (the Kelvin model). To understand the early stages of catalyst dissolution, implicit solvation techniques based on the self-consistent continuum solvation method are applied. It is demonstrated that interfacial charge and polarization can shift the dissolution energies by amounts on the order of 0.74 eV depending on the surface site and nanoparticle shape, leading to the unexpected preferential removal of platinum cations from highly coordinated sites in some cases.

Effects of a standardized emergency department protocol on after-hours use of venous duplex ultrasound.

OBJECTIVE: Vascular laboratory (VL) venous duplex ultrasound is the "gold standard" for diagnosis of lower extremity deep venous thrombosis (DVT), which is linked to many morbid conditions. Decreasing night and weekend use of VL services in the emergency department (ED) represents a potentially viable means of reducing costs as skilled personnel must remain on call and receive a wage premium when activated. We investigated the effects of workflow changes that required ED providers to use a computerized decision-making tool, integrated into the electronic medical record, to calculate a Wells score for each patient considered for an after-hours venous duplex ultrasound study for suspected DVT. METHODS: The rate of VL use and study positivity before and after implementation of the decision-making tool were examined in addition to measures of ED throughput, rate of concomitant pulmonary embolism, disposition of examined patients from the ED, observed thrombus distribution in duplex ultrasound studies positive for DVT, and calculated personnel costs of after-hours VL use. RESULTS: A total of 391 after-hours, ED-initiated venous duplex ultrasound studies were obtained during the 4-year study period (n = 213 before intervention, n = 178 after intervention; P = .12). Whereas the period immediately after the start of the intervention saw a decrease in VL use, this was not sustained. Studies performed after the intervention were not more likely to be positive for acute DVT (12.2% vs 18%; P = .1179). The average Wells score was 2.8 (range, 0-6). VL personnel were called in 347 times during the 4-year period, with a total cost of $14,643.40. Nurse-ordered studies were significantly more likely to be positive, with 22% revealing acute DVT compared with 12% for physician-ordered studies (P = .042). The intervention resulted in significant improvements in ED throughput, with time between triage and study request falling from 226 minutes to 165 minutes (P < .001). Observed thrombus distribution revealed involvement of the most proximal external iliac system in a minority of cases (11%), whereas most thrombi (89%) were limited to the femoropopliteal, calf, and superficial venous systems. CONCLUSIONS: A requirement for ED providers to document a Wells score before obtaining an after-hours venous duplex ultrasound study resulted in only a transient decrease in VL use but improved ED throughput. Studies ordered by nurses were significantly more likely to be positive, possibly as a result of consistent protocol adherence compared with the physicians. Future studies may warrant investigation into this provider variance.

Tsunamis in the geological record: Making waves with a cautionary tale from the Mediterranean.

From 2000 to 2015, tsunamis and storms killed more than 430,000 people worldwide and affected a further >530 million, with total damages exceeding US$970 billion. These alarming trends, underscored by the tragic events of the 2004 Indian Ocean catastrophe, have fueled increased worldwide demands for assessments of past, present, and future coastal risks. Nonetheless, despite its importance for hazard mitigation, discriminating between storm and tsunami deposits in the geological record is one of the most challenging and hotly contended topics in coastal geoscience. To probe this knowledge gap, we present a 4500-year reconstruction of "tsunami" variability from the Mediterranean based on stratigraphic but not historical archives and assess it in relation to climate records and reconstructions of storminess. We elucidate evidence for previously unrecognized "tsunami megacycles" with three peaks centered on the Little Ice Age, 1600, and 3100 cal. yr B.P. (calibrated years before present). These ~1500-year cycles, strongly correlated with climate deterioration in the Mediterranean/North Atlantic, challenge up to 90% of the original tsunami attributions and suggest, by contrast, that most events are better ascribed to periods of heightened storminess. This timely and provocative finding is crucial in providing appropriately tailored assessments of coastal hazard risk in the Mediterranean and beyond.

Reassessing the environmental context of the Aitape Skull - The oldest tsunami victim in the world?

There is increasing recognition of the long-lasting effects of tsunamis on human populations. This is particularly notable along tectonically active coastlines with repeated inundations occurring over thousands of years. Given the often high death tolls reported from historical events though it is remarkable that so few human skeletal remains have been found in the numerous palaeotsunami deposits studied to date. The 1929 discovery of the Aitape Skull in northern Papua New Guinea and its inferred late Pleistocene age played an important role in discussions about the origins of humans in Australasia for over 25 years until it was more reliably radiocarbon dated to around 6000 years old. However, no similar attention has been given to reassessing the deposit in which it was found-a coastal mangrove swamp inundated by water from a shallow sea. With the benefit of knowledge gained from studies of the 1998 tsunami in the same area, we conclude that the skull was laid down in a tsunami deposit and as such may represent the oldest known tsunami victim in the world. These findings raise the question of whether other coastal archaeological sites with human skeletal remains would benefit from a re-assessment of their geological context.

Anthropogenic disruption to the seismic driving of beach ridge formation: The Sendai coast, Japan.

The expected geomorphic after-effects of the Mw 9.0 Tohoku-oki earthquake of 11 March 2011 (eastern Japan) are summarized by a schematic model of seismic driving, which details seismogenic disturbances to sediment systems that affect the rate or timing of sediment delivery to coastlines over timescales of 10(2)-10(4)years. The immediate physical environmental responses to this high-magnitude earthquake included a large tsunami and extensive region-wide slope failures. Normally, slope failures within mountain catchments would have significant impacts on Japan's river and coastal geomorphology in the coming decades with, for example, a new beach ridge expected to form within 20-100 years on the Sendai Plain. However, human activity has significantly modified the rate and timing of geomorphic processes of the region, which will have impacts on likely geomorphic responses to seismic driving. For example, the rivers draining into Sendai Bay have been dammed, providing sediment traps that will efficiently capture bedload and much suspended sediment in transit through the river system. Instead of the expected ~1 km of coastal progradation and formation of a ~3m high beach ridge prior to the next large tsunami, it is likely that progradation of the Sendai Plain will continue to slow or even cease as a result of damming of river systems and capture of river sediments behind dams. The resulting reduction of fluvial sediment delivery to the coast due to modification of rivers inadvertently makes seawalls and other engineered coastal structures even more necessary than they would be otherwise.

Interdisciplinary Quality Improvement Conference: Using a Revised Morbidity and Mortality Format to Focus on Systems-Based Patient Safety Issues in a VA Hospital: Design and Outcomes.

The Veterans Healthcare Administration (VA) has embraced patient safety and quality improvement in the quest to improve care for veterans. The New Mexico VA Health Care System introduced a new morbidity and mortality conference, called the Interdisciplinary Quality Improvement Conference (IQIC), using patient case presentations to focus on underlying systems in the clinical care environment. The revised conference design also effectively teaches the 6 Accreditation Council for Graduate Medical Education (ACGME) core requirements for resident education. A formal process was established for case selection, presentation, systems issue identification, tracking, and follow-up. The IQIC has enabled the identification of more than 20 system issues at the study institution. Outcome data show lasting improvement in system issues that were addressed by this mechanism. The VA IQIC is an effective method to both identify and correct systems issues that affect patient care and is an effective method for teaching residents the 6 ACGME requirements for residency education.

There is no benefit to universal carotid artery duplex screening before a major cardiac surgical procedure.

BACKGROUND: Perioperative stroke is a devastating complication after cardiac surgery. In an attempt to minimize this complication, many cardiac surgeons routinely preoperatively order carotid artery duplex scans to assess for significant carotid stenosis. We hypothesize that the routine screening of preoperative cardiac surgery patients with carotid artery duplex scans detects few patients who would benefit from carotid intervention or that a significant carotid stenosis reliably predicts stroke risk after cardiac surgery. METHODS: A retrospective review identified 1,499 patients who underwent cardiac surgical procedures between July 1999 and September 2010. Data collected included patient demographics, comorbidities, history of previous stroke, preoperative carotid artery duplex scan results, location of postoperative stroke, and details of carotid endarterectomy (CEA) procedures before, in conjunction with, or after cardiac surgery. Statistical methods included univariate analysis and Fisher's exact test. RESULTS: Twenty-six perioperative strokes were identified (1.7%). In the 21 postoperative stroke patients for whom there is complete carotid artery duplex scan data, 3 patients had a hemodynamically significant lesion (>70%) and 1 patient underwent unilateral carotid CEA for bilateral disease. Postoperative strokes occurred in the anterior cerebral circulation (69.2%), posterior cerebral circulation (15.4%), or both (15.4%). Patient comorbidities, preoperative carotid artery duplex scan screening velocities, or types of cardiac surgical procedure were not predictive for stroke. Thirteen patients (0.86%) underwent CEA before, in conjunction with, or after cardiac surgery. Two of these patients had symptomatic disease, 1 of whom underwent CEA before and the other after his cardiac surgery. Of the 11 asymptomatic patients, 2 underwent CEA before, 3 concurrently, and 6 after cardiac surgery. Left main disease (≥50% stenosis), previous stroke, and peripheral vascular disease were found to be statistically significant predictors of carotid revascularization. A cost analysis of universal screening resulted in an estimated net cost of $378,918 during the study period. CONCLUSIONS: The majority of postoperative strokes after cardiac surgery are not related to extracranial carotid artery disease and they are not predicted by preoperative carotid artery duplex scan screening. Consequently, universal carotid artery duplex scan screening cannot be recommended and a selective approach should be adopted.

Long-term follow-up of endovascular abdominal aortic aneurysm repair in a rural veteran patient population.

BACKGROUND: The endovascular repair of abdominal aortic aneurysms (EVARs) requires follow-up to detect and treat late complications. METHODS: Two hundred eleven patients underwent EVAR for infrarenal, nonruptured abdominal aortic aneurysms from 1999 to 2010 at the Raymond G. Murphy VA Medical Center, Albuquerque, NM. A retrospective review examined patient demographics, comorbidities, the distance the patient lived from the facility, early and late complications, and the device implanted. Statistical analysis included the chi-square test for independence, the Fisher exact test, and the 2-sample Mann-Whitney U test for means. RESULTS: The mean time from the operation to the first complication was 21 months (standard deviation = 20 months) with a mean follow-up of 48 months (standard deviation = 36 months). The late complication rate was 22.8% (54 patients). Sixteen percent did not require any reinterventions, 57% were treated with percutaneous interventions, and 27% required an open surgical procedure. No single comorbidity, combination of comorbidities, distance the patient lived from the facility, or device implanted was predictive of complications. CONCLUSIONS: EVAR follow-up is essential to detect complications. When complications occur, the majority occur well after the initial treatment, and most can be treated with minimally invasive percutaneous techniques.

Diagnosis and treatment of plantar fasciitis.

Plantar fasciitis, a self-limiting condition, is a common cause of heel pain in adults. It affects more than 1 million persons per year, and two-thirds of patients with plantar fasciitis will seek care from their family physician. Plantar fasciitis affects sedentary and athletic populations. Obesity, excessive foot pronation, excessive running, and prolonged standing are risk factors for developing plantar fasciitis. Diagnosis is primarily based on history and physical examination. Patients may present with heel pain with their first steps in the morning or after prolonged sitting, and sharp pain with palpation of the medial plantar calcaneal region. Discomfort in the proximal plantar fascia can be elicited by passive ankle/first toe dorsiflexion. Diagnostic imaging is rarely needed for the initial diagnosis of plantar fasciitis. Use of ultrasonography and magnetic resonance imaging is reserved for recalcitrant cases or to rule out other heel pathology; findings of increased plantar fascia thickness and abnormal tissue signal the diagnosis of plantar fasciitis. Conservative treatments help with the disabling pain. Initially, patient-directed treatments consisting of rest, activity modification, ice massage, oral analgesics, and stretching techniques can be tried for several weeks. If heel pain persists, then physician-prescribed treatments such as physical therapy modalities, foot orthotics, night splinting, and corticosteroid injections should be considered. Ninety percent of patients will improve with these conservative techniques. Patients with chronic recalcitrant plantar fasciitis lasting six months or longer can consider extracorporeal shock wave therapy or plantar fasciotomy.

Deposits, flow characteristics, and landscape change resulting from the September 2009 South Pacific tsunami in the Samoan islands.

The September 29th 2009 tsunami caused widespread coastal modification within the islands of Samoa and northern Tonga in the South Pacific. Preliminary measurements indicate maximum runup values of around 17 m (Okal et al., 2010) and shore-normal inundation distances of up to ~ 620 m (Jaffe et al., 2010). Geological field reconnaissance studies were conducted as part of an UNESCO-IOC International Tsunami Survey Team survey within three weeks of the event in order to document the erosion, transport, and deposition of sediment by the tsunami. Data collected included: a) general morphology and geological characteristics of the coast, b) evidence of tsunami flow (inundation, flow depth and direction, wave height and runup), c) surficial and subsurface sediment samples including deposit thickness and extent, d) topographic mapping, and e) boulder size and location measurements. Four main types of sedimentary deposits were identified: a) gravel fields consisting mostly of isolated cobbles and boulders, b) sand sheets from a few to ~ 25 cm thick, c) piles of organic (mostly vegetation) and man-made material forming debris ramparts, and d) surface mud deposits that settled from suspension from standing water in the tsunami aftermath. Tsunami deposits within the reef system were not widespread, however, surficial changes to the reefs were observed.

Do post-disaster public health interventions impede malaria eradication?

In this paper, we hypothesise that public health interventions aimed at controlling post-disaster malaria epidemics may in fact impede malaria eradication efforts in the longer term. A major factor hampering malaria eradication efforts is the development of resistance to antimalarial drugs in the Plasmodium parasite. Following natural disasters such as flooding, public health responses includes a massive influx of antimalarial drugs that may facilitate the development of resistance. Resistance is common in areas with frequent natural disasters, and if such an association could be shown to be generalisable and causative, there may be direct implications for the way that future disaster-related malaria risks are managed. Because the frequency and severity of climate-associated disasters is likely to increase with global warming, it is timely to study the possibility that well intentioned public health action may in fact exacerbate the disease burden from the very parasites that it sets out to control.

Endoscopy in a deployed combat support hospital: maintaining military end-strength.

OBJECTIVE: The objective was to examine the safety and efficacy of the 48th Combat Support Hospital's use of diagnostic endoscopy in Afghanistan. METHODS: A retrospective review was performed on the medical records of all endoscopy patients treated at the 48th Combat Support Hospital in Bagram, Afghanistan, from December 6, 2002 through June 7, 2003. RESULTS: Twenty-four patients (male, 21; female, 3; mean age, 35 years) underwent 28 endoscopic procedures as follows: colonoscopy, 14; esophagogastroduodenoscopy (EGD), 13; and flexible sigmoidoscopy, 1. Four patients underwent both EGD and colonoscopy. There were no complications. Of the 18 U.S. military patients, 3 (15%) were evacuated for further evaluation and/or treatment and 1 (5%) patient underwent an elective screening colonoscopy. For 14 of 17 U.S. military personnel (82%), the endoscopic procedures obviated evacuation from Afghanistan. CONCLUSIONS: Diagnostic colonoscopy and EGD were valuable and safe adjuncts that precluded evacuations out of theater for 82% of military patients. Endoscopy should be used when U.S. military operations necessitate the deployment of large numbers of forces for protracted periods.

Operation Enduring Freedom: the 48th Combat Support Hospital in Afghanistan.

OBJECTIVE: To examine the experience of the 48th Combat Support Hospital (CSH) while deployed to Afghanistan, with an emphasis on trauma care. MATERIALS AND METHODS: Before redeployment, a retrospective review was performed on the medical records of all patients treated at the 48th CSH from December 6, 2002 through June 7, 2003. RESULTS: During the 6-month period, 10,679 patients were evaluated and/or treated. There were 477 hospital admissions (adults, 387; children, 90; trauma, 204) and 634 operating room procedures. The most common mechanisms of injury were land mines/unexploded ordinance (74 = 36%) and gunshot wounds (41 = 20%). Extremities were the most common site. A total of 358 cases was performed on 168 trauma patients (mean, 2 cases per patient; range, 1-12). There were 63 complications in 40 trauma patients and 11 patients died. CONCLUSIONS: The 48th CSH supported military and humanitarian operations with an ongoing process of re-evaluation, adaptation, and medical education that resulted in low morbidity and mortality rates.

Observations by the international tsunami survey team in Sri Lanka.

In response to the 26 December 2004 tsunami, a survey team of scientists was dispatched to Sri Lanka. Measurements made by the team show that the tsunami elevation and runup ranged from 5 to 12 meters. Eyewitnesses report that up to three separate waves attacked the coast, with the second or third generally the largest. Our conclusion stresses the importance of education: Residents with a basic knowledge of tsunamis, as well as an understanding of how environmental modifications will affect overland flow, are paramount to saving lives and minimizing tsunami destruction.