188 research outputs found
Effective Feature Representation for Clinical Text Concept Extraction
Crucial information about the practice of healthcare is recorded only in
free-form text, which creates an enormous opportunity for high-impact NLP.
However, annotated healthcare datasets tend to be small and expensive to
obtain, which raises the question of how to make maximally efficient uses of
the available data. To this end, we develop an LSTM-CRF model for combining
unsupervised word representations and hand-built feature representations
derived from publicly available healthcare ontologies. We show that this
combined model yields superior performance on five datasets of diverse kinds of
healthcare text (clinical, social, scientific, commercial). Each involves the
labeling of complex, multi-word spans that pick out different healthcare
concepts. We also introduce a new labeled dataset for identifying the treatment
relations between drugs and diseases
Treated amblyopes remain deficient in spatial vision: A contrast sensitivity and external noise study
AbstractTo evaluate residual spatial vision deficits in treated amblyopia, we recruited five clinically treated amblyopes (mean age=10.6 years). Contrast sensitivity functions (CSF) in both the previously amblyopic eyes (pAE; visual acuity=0.944±0.019 MAR) and fellow eyes (pFE; visual acuity=0.936±0.021 MAR) were measured using a standard psychophysical procedure for all the subjects. The results indicated that the treated amblyopes remained deficient in spatial vision, especially at high spatial frequencies, although their Snellen visual acuity had become normal in the pAEs. To identify the mechanisms underlying spatial vision deficits of treated amblyopes, threshold vs external noise contrast (TvC) functions â the signal contrast necessary for the subject to maintain a threshold performance level in varying amounts of external noise (âTV snowâ) â were measured in both eyes of four of the subjects in a sine-wave grating detection task at several spatial frequencies. Two mechanisms of amblyopia were identified: increased internal noise at low to medium spatial frequencies, and both increased internal noise and increased impact of external noise at high spatial frequencies. We suggest that, in addition to visual acuity, other tests of spatial vision (e.g., CSF, TvC) should be used to assess treatment outcomes of amblyopia therapies. Training in intermediate and high spatial frequencies may be necessary to fully recover spatial vision in amblyopia in addition to the occlusion therapy
Investigation of Application of Suction Line Heat Exchanger in R290 Air Conditioner with Small Diameter Copper Tube
R290 is a potential refrigerant replacing R22 because of its zero Ozone Depletion Potential (ODP) and virtually zero Global Warming Potential (GWP). However, R290 is flammable and requires excellent containment to avoid leakage and reduce the risk of fire. The use of small diameter copper tube (5 mm or even smaller) is an effective way to reduce refrigerant charge and thus reduce the risk of fire in the event of a refrigerant leak. However, employing small diameter copper tube will increase pressure drop and consequently reduce system performance. A suction line heat exchanger which employs the low temperature refrigerant in suction line to cool down the refrigerant before expansion value is a potential solution to improve system performance because R290 has low discharge temperature compared with HFC refrigerants (e.g. R22, R410A). This paper presents an investigation of application of a suction line heat exchanger in an R290 air conditioner with small diameter copper tube. A theoretical analysis is proposed at first to investigate the effect of the suction line heat exchanger on capacity and system energy efficiency under variable evaporating and cooling temperatures. A prototype R290 air conditioner with and without a suction line heat exchanger is tested in order to explore the effect of a suction line heat exchanger on system performance and refrigerant charge in real working conditions. Finally, a refrigerant circuit solution for heat pump air conditioners is proposed. The results of theoretical analysis indicate that the capacity and system energy efficiency increase linearly with the heat exchange of the suctionline heat exchanger, and the suction line heat exchanger can improves capacity by up to 12% and system energy efficiency by up to 4% under both cooling and heating modes. This is because the suction line heat exchanger increases the sub-cooling but has less impact on compressor power due to good thermal properties of R290. Further, the evaporating and condensation temperature have insignificant impact on the performance of suction line heat exchanger. The experimental results show that the suction line heat exchanger improves the cooling capacity and system efficiency by 5.3% and 4.5%, respectively. These results agree well with that of the system analysis. The sub-cooling temperature increases 10.2o C and the discharge temperature increases 25.4o C. Further, the suction line heat exchanger reduces the refrigerant charge by as much as 6%. This is because suction line heat exchanger increases the discharge temperature, and thus the superheat region of the condenser increases resulting in less refrigerant in the condenser. Overall, the use of a suction line heat exchanger in a system with small diameter copper tube improves the performance of R290 and more importantly reduces the refrigerant charge
Experimental Study of the Effects of Marrow Mesenchymal Stem Cells Transfected with Hypoxia-Inducible Factor-1α Gene
Objective. To construct the eukaryotic expression
vector hypoxia-inducible factor
1α-pcDNA3.1 and to investigate its transfective efficiency into
mesenchymal stem cells (MSCs) in vitro and the expression of
HIF-1α gene in MSCs.
Methods. mRNA of Wistar Rats' myocardial cells
was extracted, and cDNA was synthesized with Reverse Transcription
Kit, HIF-1α was
amplified by polymerase chain reaction (PCR), and constructed into
pcDNA3.1. Transfected
HIF-1α-pcDNA3.1 into MSCs by liposome mediated method. The expression
of HIF-1α in the
cells was detected by Western Blot Analysis and ELISA.
Results. Eukaryotic expression vector
HIF-1α-pcDNA3.1 was constructed successfully. Analyzed by flow
cytometer, The MSCs' surfaces mark were CD44+, SH3(CD73)+,
CD34â, CD45â and the CD44+ cells and SH3(CD73)+ cells were
94.7% and 97.3%, respectively, showing the high purity of
the cultured MSCs. After inducing, the cultured MSCs can
differentiate into osteoblasts and adipocytes successfully. In
HIF-1α gene
transfected MSCs, the expression of
HIF-1α mRNA and
HIF-1α protein were
both increased obviously. Conclusion.
HIF-1α was cloned
successfully.
HIF-1α-pcDNA3.1 can be transfected into MSCs by liposome-mediated
method effectively and which resulting stable expression of
HIF-1α in transfected
MSCs
Study on synergistic water-resisting stability of upper and lower soil layers and bedrock layer in shallow coal seam group
The roof water inrush of shallow buried coal seam is caused by the water flowing fractured zone through the aquifuge. With the downward mining of coal seam group, the mechanism of synergistic water isolation between soil layer and bedrock layer needs to be clarified. In order to analyze the failure mechanism of aquiclude under the background of downward mining of coal seam group, so as to accurately predict the water inrush problem of coal mine roof, taking the downward mining of 2â2, 3â1 and 4â2 coal seams in Han Jiawan Coal Mine of Shenfu Mining Area in Northern Shaanxi as the research background, the differences in the properties of aquiclude at different depths were obtained by in-situ borehole coring experiments. The development form of cracks is described by establishing the mechanical model of seepage expansion of upper aquifuge soil layer. Using the mechanical model of soil-rock composite aquiclude, the mechanical criterion of the lower aquiclude in the overall stable state is calculated under the condition of âgiven deformationâ. The research shows that the aquiclude can be divided into upper aquiclude and lower aquiclude according to its different properties. By comparing the total load with the tensile strength of the upper aquifuge, when the total load is less than or equal to the tensile strength of the upper aquifuge, the crack no longer develops downward to obtain the crack development length. Under the condition of âgiven deformationâ, when the tensile stress generated at the middle position of the long side of the aquiclude is less than or equal to the tensile strength threshold, the overall structure of the lower aquiclude is in a stable state, and no tensile failure will occur. According to the geological conditions of Han Jiawan coal mine, the numerical simulation results are consistent with the theoretical analysis results. The research can provide reference for roof water inrush prediction under similar geological conditions
Ferroelectricity driven by magnetism in quasi-one-dimensional Ba9Fe3Se15
The spin-induced ferroelectricity in quasi-1D spin chain system is little
known, which could be fundamentally different from those in three-dimensional
(3D) system. Here, we report the ferroelectricity driven by a tilted screw spin
order and its exotic dynamic in the spin-chain compound Ba9Fe3Se15. It is found
that the spin-induced polarization has already occurred and exhibits
magnetoelectric coupling behavior far above the long-range spin order (LRSO) at
TN = 14 K. The polarized entities grow and their dynamic responses slow down
gradually with decreasing temperature and permeate the whole lattice to form 3D
ferroelectricity at TN. Our results reveal that the short-range spin orders
(SRSOs) in the decoupled chains play a key role for the exotic dynamic in this
dimension reduced system. Ba9Fe3Se15 is the only example so far which exhibits
electric polarization above LRSO temperature because of the formation of SRSOs
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