170 research outputs found
An estimation of the Gauss curvature and the modified defect relation for the Gauss map of immersed harmonic surfaces in
Let denote a -quasiconformal harmonic
surface and let be the unit normal map of . We define
as the distance from point to the boundary of and as
the Gauss curvature of at . Assuming that the Gauss map (i.e., the
normal ) omits directions
in with the property that any three of these directions are not contained
in a plane in . Then there exists a positive constant
depending only on such that
\begin{equation*} |\mathcal{K}(p)|\leq C/d(p)^2 \end{equation*} for all points
. Furthermore, a modified defect relation for the generalized Gauss map
of the immersed harmonic surfaces in is verified
Highly functional green materials platform: Starch-ionic liquid-carbon nanotube polymer melt nanocomposites
Research on stress sensitivity of fractured carbonate reservoirs based on CT technology
Fracture aperture change under stress has long been considered as one of primary causes of stress sensitivity of fractured gas reservoirs. However, little is known about the evolution of the morphology of fracture apertures on flow property in loading and unloading cycles. This paper reports a stress sensitivity experiment on carbonate core plugs in which Computed Tomography (CT) technology is applied to visualize and quantitatively evaluate morphological changes to the fracture aperture with respect to confining pressure. Fracture models were obtained at selected confining pressures on which pore-scale flow simulations were performed to estimate the equivalent absolute permeability. The results showed that with the increase of confining pressure from 0 to 0.6 MPa, the fracture aperture and equivalent permeability decreased at a greater gradient than their counterparts after 0.6 MPa. This meant that the rock sample is more stress-sensitive at low effective stress than at high effective stress. On the loading path, an exponential fitting was found to fit well between the effective confining pressure and the calculated permeability. On the unloading path, the relationship is found partially reversible, which can evidently be attributed to plastic deformation of the fracture as observed in CT images
Alteration of Brain Structure With Long-Term Abstinence of Methamphetamine by Voxel-Based Morphometry
Background: A large portion of previous studies that have demonstrated brain gray matter reduction in individuals who use methamphetamine (MA) have focused on short-term abstinence, but few studies have focused on the effects of long-term abstinence of methamphetamine on brain structures.Materials and Methods: Our study includes 40 healthy controls and 44 abstinent methamphetamine-dependent (AMD) subjects who have abstained for at least 14 months. For every AMD subject, the age when they first used MA, the total time of MA use, the frequency of MA use in the last month before abstinence, the duration of abstinence and the craving score were recorded. Here we used magnetic resonance imaging (MRI) to measure the gray matter volume (GMV) of each subject with voxel-based morphometry method. Two-sample t-test (AlphaSim corrected) was performed to obtain brain regions with different gray matter volume (GMV) between groups. In addition, partial correlation coefficients adjusted for age, years of education, smoking, and drinking were calculated in the AMD group to assess associations between the mean GMV values in significant clusters and variables of MA use and abstinence.Results: Compared with the healthy control group, AMD group showed increased gray matter volumes in the bilateral cerebellum and decreased volumes in the right calcarine and right cuneus. Moreover, GMV of left cerebellum are positively correlated with the duration of abstinence in the AMD group (p = 0.040, r = 0.626).Conclusions: The present study showed that the gray matter volume in some brain regions is abnormal in the AMD subjects with long-term abstinence. Changes in gray matter volume of visual and cognitive function regions suggested that these areas play important roles in the progress of MA addiction and abstinence. In addition, positive correlation between GMV of the left cerebellum crus and duration of abstinence suggested that prolonged abstinence is beneficial to cognitive function recovery
Effects of parenteral nutrition of ω-3 polyunsaturated fatty acid, arginine and glutamine on cellular immune status of patients following liver cancer surgery
Purpose: To study the effects of parenteral nutrition (TPN), ω-3 polyunsaturated fatty acid (PUFA), Larginine (Arg), and glutamine on cellular immunity of patients who have done the liver cancer (LC) surgery.Methods: Seventy-five (75) LC patients were randomly divided into 5 groups (A - E; 15 cases each), group A, B, C, D and E, in which patients were treated with TPN, TPN + fish oil, TPN + Arg, TPN + glutamine, and TPN + ω-3 PUFA + Arg + glutamine, respectively. Before and after surgery, CD3 +, CD4 + and CD8 + were measured by antibody-sensitized erythrocyte rosette test, and IL-6, IL-10 and TNF-a were assayed with double-antibody sandwich enzyme-linked immunoassay (DAS-ELISA). IgA and IgM were measured nephelometrically.Results: The levels of CD3 +, CD4 + and CD8 + in group A showed no obvious change after surgery (p > 0.05). However, CD3 + and CD4 + increased in groups B, C and D, while CD8 + decreased in group E (p < 0.05). IL-6 in group E was lower than that in any of the other four groups (p < 0.05). IL-10 in group A was lower than that in groups B, C and D, but lower than in group E (p < 0.05). The levels of TNF-a in groups B and C were lower than those in group A, but higher than that in group E (p < 0.05) but lower than in group D. IgA in group E was higher than in the other groups (p < 0.05), while IgM level in group E was lower than in groups A, B and C (p < 0.05).Conclusion: Immunosuppressive status and cellular immunity of patients after liver cancer surgery may be improved by a combination therapy of TPN, ω-3 PUFAs, Arg and glutamine.Keywords: Polyunsaturated fatty acid, Arginine, Glutamine, Parenteral nutrition, Hepatoma, Cellular immunit
ChatRadio-Valuer: A Chat Large Language Model for Generalizable Radiology Report Generation Based on Multi-institution and Multi-system Data
Radiology report generation, as a key step in medical image analysis, is
critical to the quantitative analysis of clinically informed decision-making
levels. However, complex and diverse radiology reports with cross-source
heterogeneity pose a huge generalizability challenge to the current methods
under massive data volume, mainly because the style and normativity of
radiology reports are obviously distinctive among institutions, body regions
inspected and radiologists. Recently, the advent of large language models (LLM)
offers great potential for recognizing signs of health conditions. To resolve
the above problem, we collaborate with the Second Xiangya Hospital in China and
propose ChatRadio-Valuer based on the LLM, a tailored model for automatic
radiology report generation that learns generalizable representations and
provides a basis pattern for model adaptation in sophisticated analysts' cases.
Specifically, ChatRadio-Valuer is trained based on the radiology reports from a
single institution by means of supervised fine-tuning, and then adapted to
disease diagnosis tasks for human multi-system evaluation (i.e., chest,
abdomen, muscle-skeleton, head, and maxillofacial neck) from six different
institutions in clinical-level events. The clinical dataset utilized in this
study encompasses a remarkable total of \textbf{332,673} observations. From the
comprehensive results on engineering indicators, clinical efficacy and
deployment cost metrics, it can be shown that ChatRadio-Valuer consistently
outperforms state-of-the-art models, especially ChatGPT (GPT-3.5-Turbo) and
GPT-4 et al., in terms of the diseases diagnosis from radiology reports.
ChatRadio-Valuer provides an effective avenue to boost model generalization
performance and alleviate the annotation workload of experts to enable the
promotion of clinical AI applications in radiology reports
Radically Enhanced Molecular Switches
The mechanism governing the redox-stimulated switching behavior of a tristable [2]rotaxane consisting of a cyclobis(paraquat-p-phenylene) (CBPQT^4+) ring encircling a dumbbell, containing tetrathiafulvalene (TTF) and 1,5-dioxynaphthalene (DNP) recognition units which are separated from each other along a polyether chain carrying 2,6-diisopropylphenyl stoppers by a 4,4′-bipyridinium (BIPY^2+) unit, is described. The BIPY^2+ unit acts to increase the lifetime of the metastable state coconformation (MSCC) significantly by restricting the shuttling motion of the CBPQTT^4+ ring to such an extent that the MSCC can be isolated in the solid state and is stable for weeks on end. As controls, the redox-induced mechanism of switching of two bistable [2]rotaxanes and one bistable [2]catenane composed of CBPQT^4+ rings encircling dumbbells or macrocyclic polyethers, respectively, that contain a BIPY2+ unit with either a TTF or DNP unit, is investigated. Variable scan-rate cyclic voltammetry and digital simulations of the tristable and bistable [2]rotaxanes and [2]catenane reveal a mechanism which involves a bisradical state coconformation (BRCC) in which only one of the BIPY^•+ units in the CBPQT^2(•+) ring is oxidized to the BIPY2+ dication. This observation of the BRCC was further confirmed by theoretical calculations as well as by X-ray crystallography of the [2]catenane in its bisradical tetracationic redox state. It is evident that the incorporation of a kinetic barrier between the donor recognition units in the tristable [2]rotaxane can prolong the lifetime and stability of the MSCC, an observation which augurs well for the development of nonvolatile molecular flash memory devices
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