The power industry is rapidly changing as demand for eco-friendly and stable power supply increases along with global greenhouse gas emission regulations. Small-capacity renewable power sources ...represented by photovoltaics and wind are continuously increasing as a form of microgrid to supply electric power to a community or island. As a result, microgrids based on renewable resources have come into wide usage around small areas or islands in Korea. In particular, the microgrid development policy of Korea is focused on electric power quality, as well as expansion in renewable energy supply for reducing greenhouse gas emissions. From 2009, the government began to develop independent carbon-free microgrids with photovoltaic and wind powers instead of traditional power diesel generators for small islands. The goal of this paper is to investigate a feasible economic microgrid topology for implementing the carbon-free island (CFI) under an acceptable level of reliability. First, we derive three scenarios of power systems including photovoltaics, wind, battery, and fuel cells. Next, we assess economic feasibility on top of the power supply reliability of the scenarios. Then, we perform a sensitivity test to suggest economic conditions for achieving the CFI goals. Finally, we present carbon-free-based microgrid models considering the CFI policy of Korea.
Specific design and optimization of the configuration of micro-scale materials can effectively enhance battery performance, including volumetric density. Herein, we employed commercially available ...low-cost bulk silicon powder to produce multi-dimensional silicon composed of porous nanowires and micro-sized cores, which can be used as anode materials in lithium-ion batteries, by combining a metal deposition and metal-assisted chemical etching process. Nanoporous silicon nanowires of 5-8 small mum in length and with a pore size of similar10 nm are formed in the bulk silicon particle. The silicon electrodes having multi-dimensional structures accommodate large volume changes of silicon during lithium insertion and extraction. These materials show a high reversible charge capacity of similar2400 mAh g-1 with an initial coulombic efficiency of 91% and stable cycle performance. The synthetic route described herein is simple, low-cost, and mass producible (high yield of 40-50% in tens of gram scale), and thus, provides an effective method for producing high-performance anode materials.
Medical cyber-physical systems (MCPS) are life-critical, context-aware, networked systems of medical devices. These systems are increasingly used in hospitals to provide high-quality continuous care ...for patients. The need to design complex MCPS that are both safe and effective has presented numerous challenges, including achieving high assurance in system software, intoperability, context-aware intelligence, autonomy, security and privacy, and device certifiability. In this paper, we discuss these challenges in developing MCPS, some of our work in addressing them, and several open research issues.
Nanostructured Si-based materials are key building blocks for next-generation energy storage devices. To meet the requirements of practical energy storage devices, Si-based materials should exhibit ...high-power, low volume change, and high tap density. So far, there have been no reliable materials reported satisfying all of these requirements. Here, we report a novel Si-based multicomponent design, in which the Si core is covered with multifunctional shell layers. The synergistic coupling of Si with the multifunctional shell provides vital clues for satisfying all Si anode requirements for practical batteries. The Si-based multicomponent anode delivers a high capacity of similar to 1000 mA h g super(-1), a highly stable cycling retention ( similar to 65% after 1000 cycles at 1 C), an excellent rate capability ( similar to 800 mA h g super(-1) at 10 C), and a remarkably suppressed volume expansion (12% after 100 cycles). Our synthetic process is simple, low-cost, and safe, facilitating new methods for developing electrode materials for practical energy storage.
Despite over two decades of research on the neural mechanisms underlying human visual scene, or place, processing, it remains unknown what exactly a “scene” is. Intuitively, we are always inside a ...scene, while interacting with the outside of objects. Hence, we hypothesize that one diagnostic feature of a scene may be concavity, portraying “inside”, and predict that if concavity is a scene-diagnostic feature, then: 1) images that depict concavity, even non-scene images (e.g., the “inside” of an object – or concave object), will be behaviorally categorized as scenes more often than those that depict convexity, and 2) the cortical scene-processing system will respond more to concave images than to convex images. As predicted, participants categorized concave objects as scenes more often than convex objects, and, using functional magnetic resonance imaging (fMRI), two scene-selective cortical regions (the parahippocampal place area, PPA, and the occipital place area, OPA) responded significantly more to concave than convex objects. Surprisingly, we found no behavioral or neural differences between images of concave versus convex buildings. However, in a follow-up experiment, using tightly-controlled images, we unmasked a selective sensitivity to concavity over convexity of scene boundaries (i.e., walls) in PPA and OPA. Furthermore, we found that even highly impoverished line drawings of concave shapes are behaviorally categorized as scenes more often than convex shapes. Together, these results provide converging behavioral and neural evidence that concavity is a diagnostic feature of visual scenes.
Ketamine to treat super-refractory status epilepticus Alkhachroum, Ayham; Der-Nigoghossian, Caroline A; Mathews, Elizabeth ...
Neurology,
2020-October-20, 2020-10-20, 20201020, Volume:
95, Issue:
16
Journal Article
Peer reviewed
Open access
OBJECTIVETo test ketamine infusion efficacy in the treatment of super-refractory status epilepticus (SRSE), we studied patients with SRSE who were treated with ketamine retrospectively. We also ...studied the effect of high doses of ketamine on brain physiology as reflected by invasive multimodality monitoring (MMM).
METHODSWe studied a consecutive series of 68 patients with SRSE who were admitted between 2009 and 2018, treated with ketamine, and monitored with scalp EEG. Eleven of these patients underwent MMM at the time of ketamine administration. We compared patients who had seizure cessation after ketamine initiation to those who did not.
RESULTSMean age was 53 ± 18 years and 46% of patients were female. Seizure burden decreased by at least 50% within 24 hours of starting ketamine in 55 (81%) patients, with complete cessation in 43 (63%). Average dose of ketamine infusion was 2.2 ± 1.8 mg/kg/h, with median duration of 2 (1–4) days. Average dose of midazolam was 1.0 ± 0.8 mg/kg/h at the time of ketamine initiation and was started at a median of 0.4 (0.1–1.0) days before ketamine. Using a generalized linear mixed effect model, ketamine was associated with stable mean arterial pressure (odds ratio 1.39, 95% confidence interval 1.38–1.40) and with decreased vasopressor requirements over time. We found no effect on intracranial pressure, cerebral blood flow, or cerebral perfusion pressure.
CONCLUSIONKetamine treatment was associated with a decrease in seizure burden in patients with SRSE. Our data support the notion that high-dose ketamine infusions are associated with decreased vasopressor requirements without increased intracranial pressure.
CLASSIFICATION OF EVIDENCEThis study provides Class IV evidence that ketamine decreases seizures in patients with SRSE.
A fast-charging battery that supplies maximum energy is a key element for vehicle electrification. High-capacity silicon anodes offer a viable alternative to carbonaceous materials, but they are ...vulnerable to fracture due to large volumetric changes during charge-discharge cycles. The low ionic and electronic transport across the silicon particles limits the charging rate of batteries. Here, as a three-in-one solution for the above issues, we show that small amounts of sulfur doping (<1 at%) render quasi-metallic silicon microparticles by substitutional doping and increase lithium ion conductivity through the flexible and robust self-supporting channels as demonstrated by microscopy observation and theoretical calculations. Such unusual doping characters are enabled by the simultaneous bottom-up assembly of dopants and silicon at the seed level in molten salts medium. This sulfur-doped silicon anode shows highly stable battery cycling at a fast-charging rate with a high energy density beyond those of a commercial standard anode.
ABSTRACT
BACKGROUND:
Risk factors for poor quality of life (QOL) after subarachnoid hemorrhage (SAH) remain poorly described.
OBJECTIVE:
To identify the frequency and predictors of poor QOL 1 year ...after SAH.
METHODS:
We studied 1-year QOL in a prospectively collected cohort of 1181 consecutively admitted SAH survivors between July 1996 and May 2013. Patient clinical, radiographic, surgical, and acute clinical course information was recorded. Reduced QOL (overall, physical, and psychosocial) at 1 year was assessed with the Sickness Impact Profile and defined as 2 SD below population-based normative Sickness Impact Profile values. Logistic regression leveraging multiple imputation to handle missing data was used to evaluate reduced QOL.
RESULTS:
Poor overall QOL was observed in 35% of patients. Multivariable analysis revealed that nonwhite ethnicity, high school education or less, history of depression, poor clinical grade (Hunt-Hess Grade ≥3), and delayed infarction were predictors of poor overall and psychosocial QOL. Poor physical QOL was additionally associated with older age, hydrocephalus, pneumonia, and sepsis. At 1 year, patients with poor QOL had increased difficulty concentrating, cognitive dysfunction, depression, and reduced activities of daily living. More than 91% of patients with poor QOL failed to fully return to work. These patients frequently received physical rehabilitation, but few received cognitive rehabilitation or emotional-behavioral support.
CONCLUSION:
Reduced QOL affects as many as one-third of SAH survivors 1 year after SAH. Delayed infarction is the most important in-hospital modifiable factor that affects QOL. Increased attention to cognitive and emotional difficulties after hospital discharge may help patients achieve greater QOL.
North Korea experienced a catastrophic famine in the mid-1990s that resulted in millions of deaths. This study aims to build an agent-based model to understand the risk of land degradation and famine ...in North Korea and explore potential solutions to mitigate this risk. The model concept reflects the general information of collective farms in North Korea, which was set in 1960, and the abstract of the social–ecological system of North Korean agriculture. The model comprises the agent, environment, and external factors. An agent is defined as a household that decides its labor allocation and land use by how much food it has. The environment is set to multiple layers that represent the soil environment of the farm, affected by agents’ decisions. The external factors reflect a land-use restriction policy, international trade (food aid), and climate change. We calibrated the model using data from North Korea and simulated various scenarios. Our findings suggest that the famine in the model would occur around 35 years later, almost reflecting the 1995 famine in the real world. The scenario-based simulations show that additional food aid or import could delay the famine, but fundamental solutions are needed to break the vicious circle of land degradation and declining food yield. Our study provides insights into the complex adaptive system of North Korean agriculture and the critical points of famine risk. Our agent-based model can be a useful tool for policymakers and researchers to explore potential solutions and inform risk management strategies.
We demonstrate a simple process to synthesize silicon-based multicomponents viaa high-temperature annealing of bulk silicon monoxide in the presence of sodium hydroxide. The carbon-coated Si-based ...anodes exhibit a highly stable cycling performance (capacity retention of 99.5% after 200 cycles) with a reversible charge capacity of 1280 mA h g super(-1).
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