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Functionally graded materials (FGMs) in which the elemental composition intentionally varies with position can be fabricated using directed energy deposition additive manufacturing (AM). This work examines an FGM that is linearly graded from V to Invar 36 (64 wt% Fe, 36 wt% Ni). This FGM cracked during fabrication, indicating the formation of detrimental phases. The microstructure, composition, phases, and microhardness of the gradient zone were analyzed experimentally. The phase composition as a function of chemistry was predicted through thermodynamic calculations. It was determined that a significant amount of the intermetallic σ-FeV phase formed within the gradient zone. When the σ phase constituted the majority phase, catastrophic cracking occurred. The approach presented illustrates the suitability of using equilibrium thermodynamic calculations for the prediction of phase formation in FGMs made by AM despite the nonequilibrium conditions in AM, providing a route for the computationally informed design of FGMs.
Introduction: Sepsis remains a major cause of mortality. In the Emergency Department (ED), rapid identification and management of sepsis have been associated with improved outcomes. Following ED assessment, patients with infection may be directly admitted to the Intensive Care Unit (ICU), or alternatively admitted to hospital wards or sent home, with risk of future deterioration necessitating ICU admission. Little is known regarding outcomes and costs of ICU sepsis patients who are initially admitted to a ward or discharged home (delayed ICU admission), as compared to those with direct ICU admission from the ED. Methods: We analyzed a prospectively collected registry (2011-2014) of patients admitted to the ICU with a diagnosis of sepsis at two academic hospitals. We included all adult patients with an index ED visit within 72 hours of ICU admission. Patients were categorized into 3 groups: 1) Admitted directly to ICU; 2) Admitted to wards, with ICU admission within 72 hours; and 3) Sent home, with ICU admission within 72 hours. ICU length of stay (LOS) and total costs (both direct and indirect) were recorded. The primary outcome, in-hospital mortality, was analyzed using a multivariable logistic regression model, controlling for confounding variables (including patient sex, comorbidities, and illness severity). Results: 657 ICU patients were included. Of these, 338 (51.4%) were admitted directly from ED to ICU, 246 (37.4%) were initially admitted to the wards, and 73 (11.1%) were initially sent home. In-hospital mortality was lowest amongst patients admitted directly to the ICU (29.5%), as compared to patients admitted to ICU from wards (42.7%), or home (61.6%). Delayed ICU admission was associated with increased odds of mortality (adjusted odds ratio 1.85 [1.24-2.76], P<0.01) and increased median ICU LOS (11 days vs. 4 days, P<0.001). Median total costs were lowest among patients directly admitted to the ICU ($19,924, [Interquartile range [IQR], 10,333-32,387]), as compared to those admitted from wards ($72,155 [IQR, $42,771-122,749]) and those initially sent home ($45,121 [IQR, $19,930-86,843]). Conclusion: Only half of ED sepsis patients ultimately requiring ICU admission within 72 hours of ED arrival are directly admitted to the ICU. Delayed ICU admission is associated with higher mortality, LOS, and costs.
The purpose of this review is to provide an update of the research regarding the etiology, diagnosis and management of psychogenic non-epileptic seizures (PNES). A literature search using Pubmed, Ovid MEDLINE and EMBASE database was performed from 2000 up to August 2017. We have evaluated the different factors leading to PNES as well as the diagnostic approach and management of this disorder which continue to be very difficult. The coexistence of epilepsy and PNES poses special challenges and requires the coordinated efforts of the family physicians, psychiatrists, psychologists and neurologists. Although this condition has an overall poor prognosis, a multidisciplinary approach in the diagnosis and management of this disorder would likely improve the outcomes. We have proposed a diagnostic and treatment algorithm for PNES and suggested a national registry of patients suffering from this condition. The registry would contain data regarding treatment and outcomes to aid in the understanding of this entity.
Use of ketamine in the prehospital setting may be advantageous due to its potent analgesic and sedative properties and favorable risk profile. Use in the military setting has demonstrated both efficacy and safety for pain relief. The purpose of this study was to assess ketamine training, use, and perceptions in the civilian setting among nationally certified paramedics (NRPs) in the United States.
A cross-sectional survey of NRPs was performed. The electronic questionnaire assessed paramedic training, authorization, use, and perceptions of ketamine. Included in the analysis were completed surveys of paramedics who held one or more state paramedic credentials, indicated “patient care provider” as their primary role, and worked in non-military settings. Descriptive statistics were calculated.
A total of 14,739 responses were obtained (response rate=23%), of which 10,737 (73%) met inclusion criteria and constituted the study cohort. Over one-half (53%) of paramedics reported learning about ketamine during their initial paramedic training. Meanwhile, 42% reported seeking ketamine-related education on their own. Of all respondents, only 33% (3,421/10,737) were authorized by protocol to use ketamine. Most commonly authorized uses included pain management (55%), rapid sequence intubation (RSI; 72%), and chemical restraint/sedation (72%). One-third of authorized providers (1,107/3,350) had never administered ketamine, with another 32% (1,070/3,350) having administered ketamine less than five times in their career. Ketamine was perceived to be safe and effective as the vast majority reported that they were comfortable with the use of ketamine (94%) and would, in similar situations (95%), use it again.
This was the first large, national survey to assess ketamine training, use, and perceptions among paramedics in the civilian prehospital setting. While training related to ketamine use was commonly reported among paramedics, few were authorized to administer the drug by their agency’s protocols. Of those authorized to use ketamine, most paramedics had limited experience administering the drug. Future research is needed to determine why the prevalence of ketamine use is low and to assess the safety and efficacy of ketamine use in the prehospital setting.
BucklandDM, CroweRP, CashRE, GondekS, MalusoP, SirajuddinS, SmithER, DangerfieldP, ShapiroG, WankaC, PanchalAR, SaraniB. Ketamine in the Prehospital Environment: A National Survey of Paramedics in the United States. Prehosp Disaster Med. 2018;33(1):23–28.
While applications of “big data” methods to social data have exploded, applications to social science have not. I discuss why, and I review some recent applications of big data methods to applied microeconomics. I speculate on opportunities to bring more big data methods into applied economics, and on opportunities to bring more economics to big data.
There are n + 1 units. The first n units are the training sample. The remaining unit is the target. For each unit i in the training sample, a social scientist measures an r-dimensional response yi, a b-dimensional vector of background covariates xi, and a p-dimensional vector of policies zi. After observing the training sample and the target covariates xn+1, the social scientist chooses the target policy zn+1.
Data are called “big” when scale makes it impossible to use methods we might use easily on a smaller-scale problem. To fix ideas, think of ordinary least squares (OLS) as the canonical “small data” tool. The data may be big in the sense that we cannot load the product of the design matrix into working memory and invert it (large n). Or the data may be big in the sense that there are so many covariates that the OLS solution is ill-defined (b > n). Or the data may be big in the sense that the number of covariates grows with the sample (b growing as n grows).
The term “big data” is commonly applied to all of these cases, but especially to large n. The term “high-dimensional” is often applied to large r, b, or p.
Ongoing improvements in information and communication technology are making large-scale data increasingly available to governments and private actors, and hence to researchers. Much of this data – on Internet browsing habits, search queries, payment method use, interactions via social media, etc. – is social in nature and of obvious interest to social scientists. Yet most of the methodological advances in big data are occurring outside the social sciences.
In this article, I discuss the strengths and weaknesses of frontier big-data methods as tools for social science.
In studies of extragalactic radio sources with multiple compact components the determination of which components, if any, are stationary and which moving is of importance. In order to learn about the radio properties of the individual components it is also relevant to be able to register maps made at several wavelengths. Both tasks are usually not possible with VLBI because of the irrecoverable corruption of the fringe phase introduced by the propagation medium and the instrumentation. However, when two or more compact radio sources are separated by only a small angle from each other difference techniques can be used to help tackle both questions.
From five sets of VLBI observations spaced between 1972 and 1981, we estimated the positions of components of the superluminal quasar 3C 345 relative to the position of the single component of the quasar NRAO 512. The relative proper motion of the easternmost component of 3C 345, believed to be the “core”, was found to be 0.02±0.02 mas/yr. This result is consistent with the “core” being stationary and the “jet” components moving with respect to NRAO 512.
We have conducted a series of VLBI observations of the gravitational-lens images of the quasar Q0957+561 (Walsh et al., 1979), utilizing the Mark III VLBI data acquisition system (Rogers et al., 1983). The goals of our observations are to (1) map the milliarcsecond structure of the A and B images, (2) detect the predicted third image of the quasar, and (3) determine the time delay between the images. We will use these results to constrain the mass distribution of the lens and, possibly, cosmological constants.
On 1981 March 17–18 we undertook MkIII VLBI observations of the quasars 1038+528 A, B (Owen et al. 1979; Owen et al. 1980) with an array of 7 telescopes operating simultaneously at λ3.6 and λ13 cm with right circular polarization reception at each wavelength. Because the sources are ~33″ apart they could be observed simultaneously at every telescope. Thus the corrupting contributions of the propagation medium and the instrumentation were approximately the same for each of the quasars, hence allowing us to calibrate the structure phase of B with respect to a reference point chosen in the map of A using the expression
where φB and φA are the observed fringe phases, φGB and φGA are the geometric contribution with respect to the reference points chosen in each map and φSA is the structure phase contribution with respect to the reference point chosen in the A map.
Mark III VLBI observations of the pulsars PSR 0329+54 and PSR 1133+16 were made at 2.3 GHz using antennas with diameters and locations as follows: 100m, Effelsberg, West Germany (but only for SPR 0329+54); 43m Green Bank, WV, USA; and 40m, Big Pine, CA, USA. The Mark III processor at the Haystack Observatory was “gated” to compute visibility amplitudes and phases as a function of pulsar longitude. This method allowed a) an improvement of the signal to noise ration, by as much as a factor of ten in the case of PSR 1133+16, and b) an interferometric investigation of the pulse structure.
A series of VLBI observations of the gravitational lens system 0957+561 at λ13 cm has yielded the positions of the A and B images, the relative magnification of their largest discernible radio structures, and the time variability of their smallest discernible radio structures. These observations have also allowed upper limits to be placed on the flux density of an expected third image. The positions and relative magnification of the A and B images provide new information with which to constrain models of the lens that forms the images. The detection of variations in the flux densities of the cores of A and B suggests that observations at shorter wavelengths may reveal superluminal motion, which may in turn provide a means to measure the relative time delay.
On 1983 May 10–11 we undertook simultaneous λ3.6 and λ13 cm Mark III VLBI observations of the quasars 1038+528 A,B. Our experimental conditions (i.e., synthesized band, uv-coverage, etc.) were almost identical to those we used on 1981 March 17–18. Thus, we could make a direct comparison of the results from both epochs.
On June 1, 1984 we conducted a seven station 18-cm VLBI observation of the 2016+112 gravitational lens system. Preliminary brightness distributions for A and B have been obtained via model fitting. Weak correlated flux density was detected in the C component region.
We have used the relative positions and magnifications of the A and B images in the gravitational lens system 0957+561, obtained from VLBI observations, to constrain a model for the surface mass distribution of the lens. With measurements of the difference ΔτBA in propagation times associated with A and B (the “relative time delay”) and of the velocity dispersion of the main lensing galaxy, both to be obtained, our model will yield a value for H0 with an uncertainty of ∼ 20% due mainly to uncertainties in our assumptions.
Efforts to prioritize wildlife for conservation benefit from an understanding of public preferences for particular species, yet no studies have integrated species preferences with key attributes of the conservation landscape such as whether species occur on islands (where invasive exotics are the primary extinction threat) or continents (where land use change is the primary extinction threat). In this paper, we compare wildlife species preferences among children from a continental location (North Carolina, USA, n = 433) and an island location (Andros Island, The Bahamas, n = 197). Children on the island preferred feral domesticated species and different types of taxa than mainland children, perhaps due to the strongly divergent species richness between the regions (e.g. island children showed greater preferences for invertebrates, lizards and aquatic species). Boys preferred fish, birds and lizards more than girls, whereas girls preferred mammals. The fact that island children showed strong preferences for invasive species suggests challenges for conservation efforts on islands, where controlling invasive exotic species is often of paramount importance, but can conflict with cultural preferences for these same species.
Models of products and design processes are key to interacting with engineering designs and managing the processes by which they are developed. In practice, companies maintain networks of many interrelated models which need to be synthesised in the minds of their users when considering issues that cut across them. This article considers how information from product and design process models can be integrated with a view to help manage these complex interrelationships. A framework highlighting key issues surrounding model integration is introduced and terminology for describing these issues is developed. To illustrate the framework and terminology, selected modelling approaches that integrate product and process information are discussed and organised according to their levels and forms of integration. Opportunities for further work to advance integrated modelling in engineering design research and practice are discussed.
Small marine snails and abalone have been identified as high- and low-risk prey items, respectively, for exposure of threatened southern sea otters to Toxoplasma gondii, a zoonotic parasite that can cause fatal encephalitis in animals and humans. While recent work has characterized snails as paratenic hosts for T. gondii, the ability of abalone to vector the parasite has not been evaluated. To further elucidate why abalone predation may be protective against T. gondii exposure, this study aimed to determine whether: (1) abalone are physiologically capable of acquiring T. gondii; and (2) abalone and snails differ in their ability to concentrate and retain the parasite. Abalone were exposed to T. gondii surrogate microspheres for 24 h, and fecal samples were examined for 2 weeks following exposure. Concentration of surrogates was 2–3 orders of magnitude greater in abalone feces than in the spiked seawater, and excretion of surrogates continued for 14 days post-exposure. These results indicate that, physiologically, abalone and snails can equally vector T. gondii as paratenic hosts. Reduced risk of T. gondii infection in abalone-specializing otters may therefore result from abalone's high nutritional value, which implies otters must consume fewer animals to meet their caloric needs.