The groundbreaking success of deep learning in many real-world tasks has triggered an intense effort to theoretically understand the power and limitations of deep learning in the training and ...generalization of complex tasks, so far with limited progress. In this work, we study the statistical mechanics of learning in deep linear neural networks (DLNNs) in which the input-output function of an individual unit is linear. Despite the linearity of the units, learning in DLNNs is highly nonlinear; hence, studying its properties reveals some of the essential features of nonlinear deep neural networks (DNNs). Importantly, we exactly solve the network properties following supervised learning using an equilibrium Gibbs distribution in the weight space. To do this, we introduce the backpropagating kernel renormalization (BPKR), which allows for the incremental integration of the network weights layer by layer starting from the network output layer and progressing backward until the first layer’s weights are integrated out. This procedure allows us to evaluate important network properties, such as its generalization error, the role of network width and depth, the impact of the size of the training set, and the effects of weight regularization and learning stochasticity. BPKR does not assume specific statistics of the input or the task’s output. Furthermore, by performing partial integration of the layers, the BPKR allows us to compute the emergent properties of the neural representations across the different hidden layers. We propose a heuristic extension of the BPKR to nonlinear DNNs with rectified linear units (ReLU). Surprisingly, our numerical simulations reveal that despite the nonlinearity, the predictions of our theory are largely shared by ReLU networks of modest depth, in a wide regime of parameters. Our work is the first exact statistical mechanical study of learning in a family of deep neural networks, and the first successful theory of learning through the successive integration of degrees of freedom in the learned weight space.
This research investigates the microstructure and defects of powder metallurgy (PM) nickel-based superalloys prepared by spark plasma sintering (SPS). The densification, microstructural evolution, ...and precipitate phase evolution processes of FGH96 superalloy after powder heat treatment (PHT) and sintering via SPS are specifically analyzed. Experimental results demonstrate that SPS technology, when applied to sinter at the sub-solidus temperature of the γ' phase, effectively mitigates the formation of a prior particle boundary (PPB). Based on experimental and computational findings, it has been determined that the presence of elemental segregation and Al
O
oxides on the surface of pre-alloyed powders leads to the preferential precipitation of MC-type carbides and Al
O
and ZrO
oxides in the sintering necks during the hot consolidation process, resulting in the formation of PPB. This study contributes to the understanding of microstructural modifications achieved through SPS technology, providing crucial information for optimizing sintering conditions and reducing the widespread occurrence of PPB, ultimately enhancing the material performance of PM nickel-based superalloys.
The goal of this study is to investigate the functional implications of the sexual dimorphism in transporter patterns along the proximal tubule. To do so, we have developed sex-specific computational ...models of solute and water transport in the proximal convoluted tubule of the rat kidney. The models account for the sex differences in expression levels of the apical and basolateral transporters, in single-nephron glomerular filtration rate, and in tubular dimensions. Model simulations predict that 70.6 and 38.7% of the filtered volume is reabsorbed by the proximal tubule of the male and female rat kidneys, respectively. The lower fractional volume reabsorption in females can be attributed to their smaller transport area and lower aquaporin-1 expression level. The latter also results in a larger contribution of the paracellular pathway to water transport. Correspondingly similar fractions (70.9 and 39.2%) of the filtered Na
are reabsorbed by the male and female proximal tubule models, respectively. The lower fractional Na
reabsorption in females is due primarily to their smaller transport area and lower Na
/H
exchanger isoform 3 and claudin-2 expression levels. Notably, unlike most Na
transporters, whose expression levels are lower in females, Na
-glucose cotransporter 2 (SGLT2) expression levels are 2.5-fold higher in females. Model simulations suggest that the higher SGLT2 expression in females may compensate for their lower tubular transport area to achieve a hyperglycemic tolerance similar to that of males.
It is well-established that thrombus aspiration during primary percutaneous coronary intervention (PCI) in patients with acute myocardial infarction (AMI) indicates a higher thrombus burden and ...necessitates more intensive antithrombotic therapy. The bidirectional association between adverse events in AMI patients and platelet reactivity is typically observed during dual antiplatelet therapy (DAPT).BACKGROUNDIt is well-established that thrombus aspiration during primary percutaneous coronary intervention (PCI) in patients with acute myocardial infarction (AMI) indicates a higher thrombus burden and necessitates more intensive antithrombotic therapy. The bidirectional association between adverse events in AMI patients and platelet reactivity is typically observed during dual antiplatelet therapy (DAPT).To investigate platelet reactivity after DAPT in AMI patients with thrombus aspiration performed during PCI.OBJECTIVETo investigate platelet reactivity after DAPT in AMI patients with thrombus aspiration performed during PCI.In this retrospective study, we examined 269 consecutive AMI patients who underwent PCI and recorded their demographic, clinical and laboratory data. The platelet reactivity was measured with thromboelastogram (TEM).METHODSIn this retrospective study, we examined 269 consecutive AMI patients who underwent PCI and recorded their demographic, clinical and laboratory data. The platelet reactivity was measured with thromboelastogram (TEM).Ultimately, 208 patients were included in this study and divided into a Thrombus Aspiration group (N = 97) and a PCI Alone group (N = 111) based on whether thrombus aspiration was performed or not. The adenosine diphosphate (ADP)-induced platelet inhibition rate in the Thrombus Aspiration group was higher than that in the PCI Alone group (P < 0.001). Furthermore, multivariate linear regression analysis revealed that the ADP-induced platelet inhibition rate was independently associated with leukocyte count, thrombus aspiration and the combination of aspirin and ticagrelor as DAPT after adjusting for potential covariates in all AMI patients.RESULTSUltimately, 208 patients were included in this study and divided into a Thrombus Aspiration group (N = 97) and a PCI Alone group (N = 111) based on whether thrombus aspiration was performed or not. The adenosine diphosphate (ADP)-induced platelet inhibition rate in the Thrombus Aspiration group was higher than that in the PCI Alone group (P < 0.001). Furthermore, multivariate linear regression analysis revealed that the ADP-induced platelet inhibition rate was independently associated with leukocyte count, thrombus aspiration and the combination of aspirin and ticagrelor as DAPT after adjusting for potential covariates in all AMI patients.In conclusion, clinicians should exercise heightened attention towards the bleeding risk among patients undergoing PCI concomitant with Thrombus Aspiration postoperatively.CONCLUSIONIn conclusion, clinicians should exercise heightened attention towards the bleeding risk among patients undergoing PCI concomitant with Thrombus Aspiration postoperatively.
A large amount of waste activated sludge (WAS) and food waste (FW) are produced every year in China. Anaerobic co-digestion is considered to be an effective way to solve this problem. This study ...applied FW/WAS mixture as co-substrate to create different digestive environment, aiming to understand the mechanism of Fe3O4 particles in promoting AD performance. The results showed that the addition of Fe3O4 presented various performances when facing different digestive acidification stress brought by different mixing ratios of WAS and FW. Methanogenic pathways and microbial communities varied with substrates’ properties. For group A (WAS mono-digestion), the acetoclastic methanogens dominated, 20 mg/g VS (according to the iron element) Fe3O4 could promote methane production, while 200 mg/g VS Fe3O4 would inhibit microbial activity. The promoted methane production by Fe3O4 was attributable to the promotion of sludge hydrolysis. For group B (WAS: FW = 1:0.5, based on VS addition, similarly hereinafter), Fe3O4 triggered direct interspecific electron transfer (DIET) between bacteria and methanogens. For group C (WAS: FW = 1:1), the hydrogenotrophic methanogens dominated, bacteria excreted more non-conductive polysaccharides in EPS to resist unfavorable environment, thereby it prevented their contact with Fe3O4 particles. So, it was difficult for Fe3O4 to trigger DIET and promote the digestive performance of batch experiments in such condition.
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•Microbial communities determine the performance of Fe3O4 in the digestive system.•Methanogenic pathways and microbial communities vary with substrates' properties.•Fe3O4 triggers DIET in a stable state when hydrogenotrophic methanogenesis domains.•Excessive EPS prevented Fe3O4 from triggering DIET between microorganisms.
The concentrated transverse load may lead to the web crippling of pultruded GFRP sections due to the lower transverse mechanical properties. Several investigations have been conducted on the ...web-crippling behavior of the GFRP sections under room temperature. However, the web-crippling behavior is not yet understood when subjected to elevated temperatures. To address this issue, a finite element model considering the temperature-dependent material properties, Hashin failure criterion and the damage evolution law are successfully developed to simulate the web-crippling behavior of the GFRP I sections under elevated temperatures. The numerical model was validated by the web-crippling experiments at room temperature with the end-two-flange (ETF) and end bearing with ground support (EG) loading configurations. The developed model can accurately predict the ultimate loads and failure modes. Moreover, it was found that the initial damage was triggered by exceeding the shear strength at the web-flange junction near the corner of the bearing plate and independent of the elevated temperatures and loading configurations. The ultimate load and stiffness decreased obviously with the increasing temperature. At 220 °C, the ultimate load of specimens under ETF and EG loading configurations significantly decreased by 57% and 62%, respectively, whereas the elastic stiffness obviously reduced by 87% and 88%, respectively.
Shear fracture frequently occurs in timber beams and panels subjected to transverse loads. At elevated temperatures, wood will undergo complex physical and chemical processes which significantly ...affect the shear properties. In this paper, the v-notched Douglas-fir specimens with three different shear planes: (a) Radial-Tangential (RT); (b) Radial-Longitudinal (RL), and (c) Longitudinal-Radial (LR), were fabricated and tested under the elevated temperatures from 20 °C to 180 °C. The digital image correlation (DIC) technique was used to measure the shear strain. It was found that the shear plane had a significant effect on the failure modes, shear strength, and shear modulus. The shear strength and shear modulus generally decreased with the increase of temperature. However, the shear strength was significantly improved when the hardening of the dry lignin occurred between 100 °C and 140 °C. Moreover, the design curve for the shear strength in Eurocode 5 is conservative for all the specimens with different shear planes.
Background
Glucagon‐like peptide 1 receptor agonists have been shown to reduce all‐cause and cardiovascular mortality in patients with Type 2 diabetes mellitus (T2DM). The probable increase in heart ...rate hinders its early usage in acute myocardial infarction patients. In our study, we aimed to find out whether the use of liraglutide in patients with acute myocardial infarction as early as at the time of hospitalization would increase the heart rate.
Methods
This was an observational retrospective study. From December 2020 to August 2021, 200 patients with acute myocardial infarction were included in our study and divided into three groups: T2DM + liraglutide group (n = 46), T2DM + non‐liraglutide group (n = 42), and non‐T2DM group (n = 112). The primary outcomes were the differences in heart rate. Secondary outcomes were differences in systolic and diastolic blood pressure.
Results
There were no significant differences in heart rate among the three groups at admission, the day before the first shot of liraglutide, and before discharge. There was also no significant difference in heart rate between diabetic patients with acute myocardial infarction and those on liraglutide during the hospital stay. And there were no differences of beta‐blocker dosages among the three groups. Liraglutide did not affect the blood pressure during acute myocardial infarction.
Conclusions
Liraglutide did not increase the heart rate in diabetic patients during acute myocardial infarction and did not lead to an increase in the dose of beta‐blockers in the patients. It also had no effect on blood pressure and showed better efficacy in lowering glucose levels without additional hypoglycemic events.
Highlights
Glucagon‐like peptide 1 receptor agonists have been shown to reduce all‐cause and cardiovascular mortality in patients with Type 2 diabetes mellitus.
Previous studies have found that liraglutide can increase the heart rate in patients, so the use of liraglutide should be controlled in patients with acute myocardial infarction.
We found that liraglutide did not increase the heart rate of diabetic patients during acute myocardial infarction and it had no effect on blood pressure.
Therefore, liraglutide is safe for use in the early stages of acute myocardial infarction.
In
Drosophila
, olfactory information received by olfactory receptor neurons (ORNs) is first processed by an incoherent feed forward neural circuit in the antennal lobe (AL) that consists of ORNs ...(input), inhibitory local neurons (LNs), and projection neurons (PNs). This “early” olfactory information processing has two important characteristics. First, response of a PN to its cognate ORN is normalized by the overall activity of other ORNs, a phenomenon termed “divisive normalization.” Second, PNs respond strongly to the onset of ORN activities, but they adapt to prolonged or continuously varying inputs. Despite the importance of these characteristics for learning and memory, their underlying mechanisms are not fully understood. Here, we develop a circuit model for describing the ORN-LN-PN dynamics by including key neuron-neuron interactions such as short-term plasticity (STP) and presynaptic inhibition (PI). By fitting our model to experimental data quantitatively, we show that a strong STP balanced between short-term facilitation (STF) and short-term depression (STD) is responsible for the observed nonlinear divisive normalization in
Drosophila
. Our circuit model suggests that either STP or PI alone can lead to adaptive response. However, by comparing our model results with experimental data, we find that both STP and PI work together to achieve a strong and robust adaptive response. Our model not only helps reveal the mechanisms underlying two main characteristics of the early olfactory process, it can also be used to predict PN responses to arbitrary time-dependent signals and to infer microscopic properties of the circuit (such as the strengths of STF and STD) from the measured input-output relation. Our circuit model may be useful for understanding the role of STP in other sensory systems.
The use of high-strength concrete (HSC) for the steel-reinforced concrete (SRC) columns received wide attentions due to the inherent brittleness of HSC. To simultaneously enhance the strength and the ...ductility, a new type of steel-reinforced reactive powder concrete (SRRPC) column was developed. However, the seismic performance of the SRRPC column has not been well understood. Based on the previous cyclic experimental results, a theoretical hysteretic model was developed to simulate the hysteretic loops. Moreover, the Finite element model was successfully developed and validated by comparing the experimental failure modes, backbone curves and strain responses. Furthermore, the comprehensive parametric analysis was conducted based on the numerical model, showing that the lateral load-bearing capacity can be effectively improved by increasing the compressive strength of RPC, steel shape yield strength, steel shape ratio and longitudinal reinforcement ratio. However, high transverse stirrup ratio cannot improve the lateral load-bearing capacity, but it can significantly enhance the post-peak strength. As the axial compression ratio increased from 0.1 to 0.9, the lateral load-bearing capacity increased by 51.4 % while the ultimate displacement dramatically reduced by 45.6 %. Furthermore, as the shear-span ratio increased, the lateral load-bearing capacity obviously decreased although the ductility increased. Therefore, it is recommended that the axial ratio and the shear-span ratio should be reasonably controlled in the design of the SRRPC column.
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